Dear Students,
I encourage you to use this blog platform to showcase your ability to find relevant answers to questions raised during class discussion, through effective literature survey and some application of mind.
I encourage you to use this blog platform to showcase your ability to find relevant answers to questions raised during class discussion, through effective literature survey and some application of mind.
1. Name the methods used for measurement of Kla.
ReplyDeleteAns) Four methods are used for Kla measurement:
(1) Chemical Method:
It is known as the sulfite oxidation method.
It involves the determination of the maximum rate of oxidation of sodium sulfite to sodium sulfate in the presence of CoSO4 or CuSO4 catalyst.
(2) Enzymic Method (GGO):
It is a dynamic method to determine KLa in a fermenter using the glucose-glucose oxidase (GGO) system.
(3) Oxygen Balance (OB) Method
(4) Gassing out techniques:
They are of two types:
(a) Dynamic Differential Gassing-Out (DDGO) Method
(b)Dynamic Integral Gassing-Out (DIGO) Method
Out of all these methods oxygen balance over the whole system is the best method for evaluation of KLa in fermenters, because no assumption need be made on the effects of cell, surface active agents, viscosity, and forth. Linear mathematical correlation between DO concentration and the proportion of oxygen in inlet and exit air of laboratory fermenter helps in easy and rapid determination of Kla.
Stainless steel grade most commonly used in fermentation industry is 316 grade.
ReplyDeleteComposition:
Chromium:16-18%
Nickel:10-14%
Carbon:0.08%
Manganese:2%
Molybdenum:2-3%
Silicon:0.75%
Phosphorus:0.045%
Sulphur:0.03%
Nitrogen:0.10%
Iron:bal
Explain major types of steel, their composition and use.
ReplyDeleteSteel can be categorized into four types depending upon their chemical composition:
1. Alloy Steel
2. Carbon Steel
3. Stainless Steel
4. Tool Steel
1. Alloy Steel: It is composed of aluminum, chromium, copper, manganese, nickel, silicon, and titanium in varying proportions. It is used in auto parts, electric motors, pipelines, power generators, and transformers.
2. Carbon Steel: This kind of steel contains trace amounts of alloying elements.
They can further be classified into three categories –
a) Mild Steel or Low Carbon Steel has up to 0.3% carbon.
b) Medium Carbon Steel has 0.3 to 0.6% carbon.
c) High Carbon Steel has more than 0.6% carbon.
3. Stainless Steel: This kind of steel contains 10 to 20% chromium and are famed for their high corrosion resistance.
They can be further categorized based on its crystalline structure into three groups –
a) Austenitic - It contains 18% chromium, 8% nickel, and less than 0.8% carbon.
b) Ferritic - It contains trace amounts of nickel, 12-17% chromium, less than 0.1% carbon and other alloying elements such as aluminum, molybdenum, or titanium.
c) Martensitic - It contains 11-17% chromium, less than 0.4% nickel, and 1.2% carbon.
4. Tool Steel : It is made using cobalt, molybdenum, tungsten and vanadium in varying quantities to increase its durability and heat resistance.
There are three categories of tool steel which based on their shapes and applications –
a) Long or Tubular Products - mostly used in the automotive and construction industries.
b) Flat Products - used in appliances, automotive parts, constructions, packaging, and shipbuilding.
c) Other products made using tool steel includes fittings, flanges, piping, and valves.
Stainless steel grade 314 has excellent high-temperature resistance characteristics among the chromium-nickel steels series. The silicon content in this material improves oxidation and carburization resistance; however, it can become very brittle when subjected to prolonged temperatures of 649-816°C (1200- 1500°F).
ReplyDeleteElement Content (%)
Iron, fe Balance
Chromium, Cr 23-26
Nickel, Ni 19-22
Manganese, Mn 2
Silicon, Si 1.5-3
Carbon, C 0.25
Sulfur, S 0.03
Phosphorous, P 0.045
Properties Metric Imperial
Tensile strength 689 MPa 99900 psi
Yield strength 345 MPa 50000 psi
Modulus of elasticity 200 GPa 29000 ksi
Elongation at break (in 50 mm) 40% 40%
Hardness, Rockwell B 85 85
Stainless Steel - Grade 317 (UNS S31700) - AZoM
ReplyDeletehttps://www.azom.com › article
Stainless Steel - Grade 316 (UNS S31600) - AZoM
https://www.azom.com › article
Q: Explain Stainless steel , Mild Steel and Steel No. 316
ReplyDeleteStainless steel:
It is defined as a steel alloy with a minimum of 11.5 wt% chromium content. Stainless steel does not stain, corrode or rust as easily as ordinary steel (it “stains less”), but it is not stain-proof. It is also called corrosion resistant steel when the alloy type and grade are not detailed, particularly in the aviation industry. There are different grades and surface finishes of stainless steel to suit the environment to which the material will be subjected in its lifetime. Common uses of stainless steel are cutlery and watch straps.
Stainless steel differs from carbon steel by amount of chromium present. Carbon steel rusts when exposed to air and moisture. This iron oxide film is active and accelerates corrosion by forming more iron oxide. Stainless steels have sufficient amount of chromium present so that a passive film of chromium oxide forms which prevents further corrosion.
Mild steels:
Carbon steel is sometimes referred to as ‘mild steel’ or ‘plain carbon steel’. The American Iron and Steel Institute defines a carbon steel as having no more than 2 % carbon and no other appreciable alloying element. Carbon steel makes up the largest part of steel production and is used in a vast range of applications.
Typically carbon steels are stiff and strong. They also exhibit ferromagnetism ( They are magnetic). This means they are extensively used in motors and electrical appliances. Welding carbon steels with a carbon content greater than 0.3 % requires that special precautions be taken. However, welding carbon steel presents far fewer problems than welding stainless steels. The corrosion resistance of carbon steels is poor (They rust) and so they should not be used in a corrosive environment unless some form of protective coating is used.
Type 316 steel:
Type 316 steel is an austenitic chromium-nickel stainless steel that contains between two and three percent molybdenum. The molybdenum content increases corrosion resistance, improves resistance to pitting in chloride ion solutions and increases strength at high temperatures.
Type 316 grade stainless steel is particularly effective in acidic environments. This grade of steel is effective in protecting against corrosion caused by sulphuric, hydrochloric, acetic, formic, and tartaric acids, as well as acid sulphates and alkaline chlorides.
Q. In Industry there is more use of Batch fermentation than Continuous fermentation...
ReplyDeleteIn Batch fermentation easy to set up and run than continuous fermentation. In continuous Fermentation it requires sophisticated instrumentation. Batch fermentation is more suitable for the production of secondary metabolites (ex. Antibiotics). Batch Fermentation, Less initial investment required and Labour demand is also less. In Batch Fermentation, after fermentation is over, the residues are taken out from the fermentation tank, and vessel is then cleaned and sterile before next batch of fermentation so that Chance of contamination is less than continuous fermentation. And easy and quick control methods.
18MMB015
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ReplyDeleteMethods used for the measurement of KLa:
ReplyDelete1)The sulphate oxidation technique:-
Cooper et al.(1994)were the first to describe the determination of oxygen-transfer rates in aerated vesels by the oxidation of sodium sulphite solution.
2)Gassing-out techniques:-
The estimation of the KLa of fermentation system by gassing out techniques depends upon monitoring the increase in dissolved oxygen concentration of a solution during aeration and agitation.
■The static method of gassing out:-
In this technique,first described by Wise(1951),the oxygen concentration of the solution is lowered by gassing the liquid out with nitrogen haa, so that the solution is 'scrubbed' free of oxygen.The deoxygenated liquid is then aerated and agitated and the increase in dissolved oxygen monitored using some form of dissolved oxygen monitored using some form of dissolved oxygen probe.
■The dynamic method of gassing out:-
Taguchi and Humphrey (1996)utilized the respiratory activity of a growing culture in the fermenter to lower the oxygen level prior to aeration.Therefore, the estimation has the advantages of being carried out during a fermentation which should gives a more realistic assessment of the fermenter's efficiency.
3)The oxygen-balance technique:-
The KLa of fermenter may be measured during a fermentation by the oxygen balance technique which determines, directly the amount of oxygen transferred into solution in a set time interval.
4)Enzymatic method:-
This methods determines KLa by using Glucose-glucose oxidase(GGO) system.
Most widely used stainless steel in fermentation industry is type 316:
ReplyDeleteAlloys often are added to steel to increase desired properties. Marine grade stainless steel, called type 316, is resistant to certain types of interactions. There are a variety of different types of 316 stainless steels, including 316 L, F, N, H, and several others. Each is slightly different, and each is used for different purpose
While similar to Type 304, which is common in the food industry, type 316 exhibit better corrosion resistance and is stronger at elevated temperatures. It is also non-hardenable by heat treatment and can be readily formed and drawn
Type 316 steel is an austenitic chromium-nickel stainless steel that contains between two and three percent molybdenum. The molybdenum content increases corrosion resistance, improves resistance to pitting in chloride ion solutions and increases strength at high temperatures.
Type 316 grade stainless steel is particularly effective in acidic environments. This grade of steel is effective in protecting against corrosion caused by sulfuric, hydrochloric, acetic, formic, and tartaric acids, as well as acid sulfates and alkaline chlorides.
Physical Properties of type 316 steel:
Density: 0.799g/cm3
Electrical resistivity: 74 microhm-cm (20 degrees Celsius)
Specific Heat: 0.50 kJ/kg-K (0-100 degrees Celsius)
Thermal conductivity: 16.2 W/m-k (100 degrees Celsius)
Modulus of Elasticity (MPa): 193 x 103 in tension
Melting Range: 2,500-2,550 degrees Fahrenheit (1,371-1,399 degrees Celsius)
A breakdown of the percentages of various elements used to create type 316 steel
Element(%)-
Carbon- 0.08
Manganese- 2.00
Phosphorus- 0.045
Sulfur- 0.03
Silicon- 0.75
Chromium- 16.00-18.00
Nickel -10.00-14.00
Molybdenum 2.00-3.00
Nitrogen- 0.10 max.
Iron- Balance
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ReplyDeleteQ. which are the method available measurement of the Kla.
ReplyDeleteANS... Four methods are available for measurement of kla.
(1) Chemical Method( sulfite oxidation method)
(2) Enzymatic Method (GGO)
(3) Oxygen Balance (OB) Method
(4) Gassing out techniques
it further divide in two type:
(a) Dynamic Differential Gassing-Out (DDGO) Method
(b)Dynamic Integral Gassing-Out (DIGO) Method
from these these methods oxygen balance over the whole system is the best method for evaluation of KLa in fermenters, because no assumption need be made on the effects of cell, surface active agents, viscosity, and forth. Linear mathematical correlation between DO concentration and the proportion of oxygen in inlet and exit air of laboratory fermenter helps in easy and rapid determination of Kla.
roll no=18mbt012
stainless steel type 316
ReplyDeleteThat mostly used in manufacturing of fermentor.
COMPOSITION.
Chromium:16-18%
Nickel:10-14%
Carbon:0.08%
Manganese:2%
Molybdenum:2-3%
Silicon:0.75%
Phosphorus:0.045%
Sulphur:0.03%
Nitrogen:0.10%
Iron:bal
316 are austenitic stainless steels that contain molybdenum, which increases their resistance to many chemical corrodents and marine environments. These materials are more resistant to general corrosion and pitting/crevices than conventional austenitic stainless steels. They also offer higher creep, stress-to-rupture and tensile strength at elevated temperatures, excellent corrosion resistance and strength properties, and they are well suited for fabricated or formed applications.
roll no.=18mbt012
- Methods used for measurement of Kla.
ReplyDelete(1) Chemical Method:
The chemical method is known as the sulfite oxidation method.
(2). Dynamic Differential Gassing-Out (DDGO) Method
(3). Dynamic Integral Gassing-Out (DIGO) Method
(4). Oxygen Balance (OB) Method
(5). Enzymic Method (GGO)
18mbt014
-MILD STEEL
ReplyDelete-Mild steel Composition
Mild steel contains
carbon 0.16 to 0.18 % (maximum 0.25% is allowable)
Manganese 0.70 to 0.90 %
Silicon maximum 0.40%
Sulfur maximum 0.04%
Phosphorous maximum 0.04%
Mildest grade of carbon steel or mild steel contains a very low amount of carbon - 0.05 to 0.26%
Mild Steel Properties
A small amount of carbon makes mild steel to change it properties.
Different amount of carbon produces different types of steels. There are small spaces between the iron lattice. Carbon atoms get attached to this spaces and makes it stronger and harder. The harder the steel the lesser the ductility.
The modulus of elasticity calculated for the industry grade mild steel is 210,000 Mpa. It has a average density of about 7860 kg/m3.
Mild steel is a great conductor of electricity. So it can be used easily in the welding process.
Because of its malleability, mild steel can be used for constructing pipelines and other construction materials. Even domestic cookwares are made of mild steel. It is ductile and not brittle but hard.
Mild steel can be easily magnetized because of its ferromagnetic properties. So electrical devices can be made of mild steel.
Mild steel is very much suitable as structural steel. Different automobile manufacturers also use mild steel for making the body and parts of the vehicle.
Mild steel can be easily machined in the lathe, shaper, drillling or milling machine. Its hardness can be increased by the application of carbon.
Mild steel is very much prone to rust because it has high amount of carbon. When rust free products are needed people prefer stainless steel over mild steel.
-STAINLESS STEEL
stainless steel, also known as inox steel or inox from French inoxydable (inoxidizable), is a steel alloy with a minimum of 10.5% chromium content by mass and a maximum of 1.2% carbon by mass.
Stainless steels are most notable for their corrosion resistance, which increases with increasing chromium content. Additions of molybdenum increase corrosion resistance in reducing acids and against pitting attack in chloride solutions. Thus, there are numerous grades of stainless steel with varying chromium and molybdenum contents to suit the environment the alloy must endure. Stainless steel's resistance to corrosion and staining, low maintenance, and familiar luster make it an ideal material for many applications where both the strength of steel and corrosion resistance are required.
-What is Type 316 stainless steel?
Type 316 stainless steel is an austenitic chromium-nickel stainless and heat-resisting steel with superior corrosion resistance as compared to other chromium-nickel steels when exposed to many types of chemical corrodents such as sea water, brine solutions, and the like. Since Type 316 stainless steel alloy contains molybdenum bearing it has a greater resistance to chemical attack than 304. Type 316 is durable, easy-to-fabricate, clean, weld and finish. It is considerably more resistant to solutions of sulfuric acid, chlorides, bromides, iodides and fatty acids at high temperature. Stainless steels containing molybdenum are required in the manufacture of certain pharmaceuticals in order to avoid excessive metallic contamination.
Element Percent by Weight 316 Stainless
C Carbon 0.08 max
Mn Manganese 2.00 max
Si Silicon 0.75 max
Cr Chromium 16.00 - 18.00
Ni Nickel 10.00 - 14.00
Mo Molybdenum 2.00 - 3.00
P Phosphorus 0.045 max
S Sulfur 0.030 max
N Nitrogen 0.10 max
Applications:
Food preparation equipment, especially in chloride environments
Chemical processing, equipment
Laboratory benches and equipment
Rubber, plastics, pulp & paper machinery
Pollution control equipment
Boat fittings, value and pump trim
Heat exchangers
Pharmaceutical and textile industries
Condensers, evaporators and tanks
18MBT014
18mbt038
ReplyDeleteQuestion: Name that methods which is used for the measurement of kla?
ans.There are five types are methods are used:
1) chemical method (sulfite oxidation method).
2) Dynamic differntidif gassing out(DDGO)method.
3) Dynamic integral gassing out (DIGO) method.
4) oxygen balance (OB) method.
5) Enzymic method (GGO) glucose-glucose oxidase.
18mbt038
ReplyDeleteQuestion: Types of steel and their composition.
ans: There is four types of the steel different based on the different amount of carbon and alloys:
1)carbon steel:
Carbon steel is dull and matte in appearance and is vulnerable to corrosion. Carbon steel can contain other alloys, such as mn,si and cu. There are three main types of carbon steel: low carbon steel, medium carbon steel, and high carbon steel.
2) Alloys steel:
Alloy steels are a mixture of several metals, including nickel, copper, and aluminum. Alloy steels tend to be cheaper and are used in mechanical work. The strength and property of alloy steels depends on the concentration of elements they contain.
3) stainless steel:
Stainless steels are shiny, corrosion resistant, and used in many products, including home appliances, backsplashes and cooking utensils. It has a low carbon content Stainless steel contains the alloy chromium and can also include nickel or molybdenum. Stainless steel is strong and can withstand high temperatures.
4)Tool steel:
Tool steel refers to a variety of carbon and alloy steels that are particularly well-suited to be made into tools. Their suitability comes from their distinctive hardness, resistance to abrasion and deformation, and their ability to hold a cutting edge at elevated temperatures.
Type 316 and type 304 stainless steel:
The two most common stainless steel grades are 304 and 316. The key difference only is addition of molybdenum, an alloy which drastically enhances corrosion resistance, especially for more saline or chloride-exposed environments. 316 stainless steel contains molybdenum, but 304 doesn't.and it contains the 304 contains 18% chromium and 8% nickel while 316 contains 16% chromium, 10% nickel and 2% molybdenum. The molybdenum is added to help resist corrosion to chlorides.
The molybdenum gives 316 better overall corrosion resistant properties than Grade 304, particularly higher resistance to pitting and crevice corrosion in chloride environments.
The type 316 grades stainless steel is more used than type 314 stainless steel.
Different types of steel widely used in the construction of a fermentor and the proportion of C, Ni, Cr in different types of steel.
ReplyDeleteAns: Pilot scale and large scale vessels are normally constructed of stainless steel or at least have a stainless steel cladding to limit corrosion. The American Iron and Steel Institute (AISI) states that steels containing less than 4% chromium are classified as steel alloys and those containing more than 4% are classified as stainless steel. Mild steel coated with glass or phenolic epoxy materials has occasionally been used. Wood,concrete and plastic have been used when contamination was not a problem in a process. Although stainless steel is often quoted as the only satisfactory material, it has been reported that mild-steel vessels were very satisfactory after 12 years use for penicillin fermentation and mild steel clad with stainless steel has been used for at least 25 years for acetone-butanol production. The corrosion resistance of stainless steel is thought to depend on the existence of a thin hydrous oxide film on the surface of metal. The composition of this film varies with different steel alloys and different manufacturing process treatment. The film is stabilized by chromium and is considered to be continuous, non-porous, insoluble and self healing. If damaged, the film will repair itself when exposed to air or an oxidizing agent. The minimum amount of chromium needed to resist corrosion will depend on the corroding agent in a particular environment, such as acid, alkalis, gases, soil, salt or fresh water. Increasing the chromium concentration enhances the resistance to corrosion, but only grades of steel containing at least 10 to 13% chromium develop the effective film. The inclusion of nickel in high percent chromium steels enhances resistance and improves their engineering properties. The presence of molybdenum improves the resistance of stainless steels to solution of halogens salts. Corrosion resistance can also be improved by tungsten, silicon and other elements.
AISI grade 316 steels which contains 18% chromium, 10% nickel, 2-2.5% molybdenum are now commonly use for fermenter or bioreactor construction. In citric acid fermentation where pH may be 1 to 2, it will be necessary to use a stainless steel with 3-4% molybdenum (AISI grade 317) to prevent leaching of heavy metals from the steel which would interfere with the fermentation. AISI grade 304, which contains 18.5% chromium and 10% nickel, is used extensively for brewing equipment. With plant and animal cell tissue culture, a low-carbon version (type 316L) is often used.
Uditi Raval
18mmb023
four different types of steel that are classified based on their chemical structure and physical properties: carbon steels, alloy steels, stainless steels, and tool steels. We'll outline each of the following steel types below.
ReplyDeleteCarbon Steel
Carbon steel is dull and matte in appearance and is vulnerable to corrosion. Carbon steel can contain other alloys, such as manganese, silicon, and copper. There are three main types of carbon steel: low carbon steel, medium carbon steel, and high carbon steel. Low carbon steel is the most common and typically contains less than .30% of carbon. Medium carbon steel contains up to .60% of carbon as well as manganese and is much stronger than low carbon steel. High carbon steel contains up to 1.5% carbon steel and is the strongest of the categories and can often be hard to work with.
Alloy Steel
Alloy steels are a mixture of several metals, including nickel, copper, and aluminum. Alloy steels tend to be cheaper and are used in mechanical work, car parts, pipelines, and motors. The strength and property of alloy steels depends on the concentration of elements they contain.
Stainless Steel
Stainless steels are shiny, corrosion resistant, and used in many products, including home appliances, backsplashes and cooking utensils. It has a low carbon content Stainless steel contains the alloy chromium and can also include nickel or molybdenum. Stainless steel is strong and can withstand high temperatures. There are more than 100 grades of stainless steel, making it an extremely versatile material that is customizable depending on your purpose.
The two most common stainless steel grades are 304 and 316. The key difference is the addition of molybdenum, an alloy which drastically enhances corrosion resistance, especially for more saline or chloride-exposed environments. 316 stainless steel contains molybdenum, but 304 doesn't.
Tool Steel
Tool steels are hard and heat and scrape-resistant. They are named tool steels because they are often used to make metal tools, such as stamping, cutting, and mold-making tools. They are also commonly used to make hammers. There are several different grades of steel that can be used for distinct applications
Methods to measure KLa
The technique of dynamic measurements normally consists of following the dissolved oxygen concentration during a step change in the inlet gas concentration.
Types
1. Sulphite oxidising technique
2. Gassing out technique
3.Oxygen balance technique
What is the difference between Steel grade 304, 316, 317?
ReplyDeleteGrade 304, 316, and 317 stainless steel are all considered austenitic stainless steel alloys. These alloys all share some similar properties, such as high strength, corrosion resistance, and high concentrations of chromium and nickel.
Type 304 is the most widely used austenitic stainless steel, and it's also known as "18-8" stainless steel because of its composition – it includes 18 percent chromium and 8 percent nickel. It has good forming and welding properties, as well as strong corrosion resistance and strength.
Higher-numbered alloys have added molybdenum in their formulation—grade 316 has about 2-3% molybdenum, and grade 317 has more than 3% molybdenum.They also offer higher creep, stress-to-rupture and tensile strength at elevated temperatures, excellent corrosion resistance and strength properties.
This added molybdenum greatly improves the steel’s resistance to pitting from chlorides, which is why grade 316 is often used in the chemical processing and marine industries.Hence they are commonly used for fermenter or bioreactor construction.
However, this added molybdenum content also influences the cost of these two alloys.The exact extra cost varies based on the market at the time.
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ReplyDelete18mbt013
ReplyDeleteSteel is an alloy of iron and carbon and other elements. Because of its high tensile strength and low cost, it is a major component used in buildings, infrastructure, tools, ships, automobiles, machines, appliances, and weapons.
Carbon Steels
Carbon steels contain trace amounts of alloying elements and account for 90% of total steel production. Low Carbon Steels/Mild Steels contain up to 0.3% carbon
Medium Carbon Steels contain 0.3-0.6% carbon
High Carbon Steels contain more than 0.6% carbon
Alloy Steels
Alloy steels contain alloying elements (e.g. manganese, silicon, nickel, titanium, copper, chromium, and aluminum) in varying proportions in order to manipulate the steel's properties, such as its hardenability, corrosion resistance, strength, formability, weldability or ductility. Applications for alloys steel include pipelines, auto parts, transformers, power generators and electric motors.
Stainless Steels
Stainless steels generally contain between 10-20% chromium as the main alloying element and are valued for high corrosion resistance. With over 11% chromium, steel is about 200 times more resistant to corrosion than mild steel. Futher it is divided into 3 types
Austenitic: Austenitic steels are non-magnetic and non-heat-treatable, and generally contain 18% chromium, 8% nickel and less than 0.8% carbon. Austenitic steels form the largest portion of the global stainless steel market and are often used in food processing equipment, kitchen utensils, and piping.
Ferritic: Ferritic steels contain trace amounts of nickel, 12-17% chromium, less than 0.1% carbon, along with other alloying elements, such as molybdenum, aluminum or titanium. These magnetic steels cannot be hardened by heat treatment but can be strengthened by cold working.
Martensitic: Martensitic steels contain 11-17% chromium, less than 0.4% nickel, and up to 1.2% carbon. These magnetic and heat-treatable steels are used in knives, cutting tools, as well as dental and surgical equipment.
Tool Steels
Tool steels contain tungsten, molybdenum, cobalt and vanadium in varying quantities to increase heat resistance and durability, making them ideal for cutting and drilling equipment.
Kla,know as the volumetric mass transfer coefficient.
Volumetric mass transfer coefficient is used as measure of the aeration capacity of a fermenter.
Three methods
Sulphite oxidation technique.
Gassing out techniques.
Oxygen balance technique.
Q) 4 methods for measurement of KLa? Which is more reliable and which is cheap?
ReplyDeleteAns: 4 methods used for measurement are:
1) Chemical Method:
It is also known as sulfide oxidation method.
It involves the determination of the maximum rate of
oxidation of sodium sulfide to sodium sulfate in the presence
of CoSo4 or CuSO4 catalyst, in which there is no back
pressure of dissolved oxygen.
2) Oxygen Balance Method (OB):
It is only based on the oxygen content.
3) Enzymatic Method:
In this method enzymes such as glucose oxidase is used.The
rate of oxygen absorption in the enzymatic method is measured
in a mechanically agitated dispersion (MAD) of gas.
4) Gassing-Out Method:
There are 2 types in this method:
a)Dynamic Differential Gassing-out
b)Dynamic Integral Gassing-out
The most reliable method is Chemical Method and the cheaper method is Oxygen Balance Method.
Q) Difference between Mild steel,316,314 and 317 steel? which is
the most widely used steel for making of Fermenters?
Ans: Mild Steel:
Mild steel involves a combination of iron ore and coal.
Once the coal and iron ore are extracted from the earth,
they are melted together in a blast furnace.
Mild steel contains approximately 0.05–0.25% carbon making
it malleable and ductile. Mild steel has a relatively low
tensile strength, but it is cheap and easy to form.
Stainless steel grade 314 has excellent high-temperature
resistance characteristics among the chromium-nickel steels
series. The silicon content in this material improves
oxidation and carburization resistance; however, it can
become very brittle when subjected to prolonged
temperatures of 649-816°C (1200- 1500°F).
Stainless Steel 316 is the standard molybdenum-bearing
grade it is extensively used in heavy gauge welded
components.The austenitic structure also gives these grades
excellent toughness, even down to cryogenic temperatures.It
offers higher creep, stress to rupture and tensile strength
at elevated temperatures.
317 stainless steel is a modified version of 316 stainless
steel. It has high strength and corrosion resistance. It c
an be heated at very high temperature such as 1149-1260°C.
Roll no: 18MBT001
Ques- Methods used for measurmemt of kla? Which is reliable?
ReplyDelete1) chemical method (for sulfite oxidation method).
2) Dynamic differential gassing-out method (DDGO).
3) Dynamic integral gassing out method (DIGO)
4) Oxygen balance method (OB)
5) Enzymatic method (GGO)
Oxygen balance method is the most reliable method.
18mbt016
Q) What are Newtonian and Non-Newtonian
ReplyDeletefluids and their role in
fermentation?
Ans:- Newtonian fluids are named after Sir Issac Newton (1642 - 1726) who described the flow behavior of fluids with a simple linear relation between shear stress [mPa] and shear rate [1/s]. This relationship is now known as Newton's Law of Viscosity, where the proportionality constant η is the viscosity [mPa-s] of the fluid.
In reality most fluids are non-Newtonian, which means that their viscosity is dependent on shear rate (Shear Thinning or Thickening) or the deformation history (Thixotropic fluids). In contrast to Newtonian fluids, non-Newtonian fluids display either a non-linear relation between shear stress and shear rate, have a yield stress, or viscosity that is dependent on time or deformation history (or a combination of all the above!)
Some examples of Newtonian fluids include water, organic solvents, and honey.
The viscous nature or the rheological properties will affect the mixing regimes of the fermentor.
Viscosity is not a simple but a complex phenomena that is always changing and responding to various parameters. Very rarely can we describe a fermentation broth as following a Newtonian behaviour. In most cases it is a complex combinations of various Non Newtonian behaviour.
This poor understanding of the fluid behaviour of the fermentation broth will affect the efficiency of mixing and liquid circulations resulting in poorly controlled or less economical fermentation process.
IMPACT OF VISCOSITY ON FERMENTATION ------------------------------------
The most crucial effect of viscosity is that it makes the situation very difficult to achieve proper and complete mixings. This will affect the various mass transfer processes that occur in the fermentor. poor mixings due to high viscosity will also result in the formation of various physical and chemical gradients.
Viscosity makes scaling up studies difficult due to the change in behaviour of the fermentation broth such as difficulty in mass heat transfers, solubility of components and gases and mixings at the upper scale of fermentation process.
18mmb012
What are the categories of non-profit Newtonian fluids?
ReplyDeleteAnd: there are 4 categories of non Newtonian fluids,
1. Thioxotropic : viscosity decreases with stress over time
2.rheopectic : viscosity increases over time.
3.shear thinning : viscosity decreases with increased stress.
4. Dilatant or shear thickening : viscosity increases with increased in stress.
(18mmb006)
Non- Newtonian* fluids in question.
DeleteWhy does lipase not work efficiently on pickle oil?
ReplyDeleteMethods for evaluation of removal of oil stains by
detergent lipases from fabrics
Lipases are used in the detergent formulation in
order to remove lipidic stains since they are active in
solution and at the water-oil interface. During soiled
fabric washing, the lipase activity depends on
washing solution composition, temperature and pH,
washing time and fabric type. The washing conditions
may be optimized by RSM since a higher washing
efficiency is required20,27
. Some lipases are unstable in
the presence of the detergents during washing. One of
the strategy used is first to presoak the fabrics to be
washed in the lipase wash solution and then wash
with a detergent solution. An appreciable dirt loss was
observed by using a pre-wash formulation with the
alkaline lipase of T. asahii MSR 54 at an ambient
washing temperature22.
Describe Rheology, its types and effect on fermentation
ReplyDeleteRheology is the study of flow and deformation of materials under applied forces.
It is classified as:
1) Newtonian fluids : Obeys Newton's law.
Viscosity changes with temperature
2) Non Newtonian Fluids : Doesn't obey Newton's law
Viscosity changes with the strain rate.
3) Pseudoplastic Rheology
4) Bingham Plastic Rheology
5) Dilatant Rheology
6) Casson Body Rheology
The viscous nature or the rheological properties will affect the mixing regimes of the fermentor.
Viscosity is a complex phenomena that is always changing and responding to various parameters. Very rarely can we describe a fermentation broth as following a Newtonian behaviour. In most cases it is a complex combinations of various Non Newtonian behaviour.
This poor understanding of the fluid behaviour of the fermentation broth will affect the efficiency of mixing and liquid circulations resulting in poorly controlled or less economical fermentation process.
Impacts of Viscosity on Fermentation.
ReplyDeleteThe viscousness of the fermentation broth is caused by the interactions of the various components in the fermentation broth. The interactions may occur between the components of the broth and the water or it could result from the interactions between the components themselves.
Impacts: - Very difficult to achieve proper and complete mixing.
- Affects various mass transfer processes.
- Result in the formation of various physical and chemical gradients due to poor mixing.
- Makes scaling up studies difficult due to the change in behaviour of the fermentation broth.
(18MBT028)
Q) What are Newtonian and Non-Newtonian
ReplyDeletefluids?
A) NEWTONIAN FLUIDS:
The fluids which obey newtons law of viscosity are known as Newtonian fluids. viscosity of Newtonian fluids remains constant, no matter the amount of shear applied for a constant temperature.These fluids have a linear relationship between viscosity and shear stress.
Examples:Water Mineral oil Gasoline Alcohol.
B)NON NEWTONIAN FLUIDS:
non-Newtonian fluids are the opposite of Newtonian fluids. When shear is applied to non-Newtonian fluids, the viscosity of the fluid changes. The behavior of the fluid can be described one of four ways:
DILATENT: Viscosity of the fluid increases when shear is applied.
PSEUDOPLASTIC: is the opposite of dilatant; the more shear applied, the less viscous it becomes. For example:Ketchup
RHEOPECTIC:is very similar to dilatant in that when shear is applied, viscosity increases. The difference here, is that viscosity increase is time-dependent.
THIXOTROPIC: decrease in viscosity when shear is applied. This is a time dependent property.
We need to know the difference to fully understand the properties of the fluids you're transferring, mixing, or pumping because viscosity plays a major role in sizing and selecting equipment.
18mmb026
NEWTONIAN FLUIDS
ReplyDeleteA Newtonian fluid's viscosity remains constant, no matter the amount of shear applied for a constant temperature.. These fluids have a linear relationship between viscosity and shear stress.
Examples:
Water
Mineral oil
Gasoline
Alcohol
NON-NEWTONIAN FLUIDS
You can probably guess that non-Newtonian fluids are the opposite of Newtonian fluids. When shear is applied to non-Newtonian fluids, the viscosity of the fluid changes. The behavior of the fluid can be described one of four ways:
Dilatant - Viscosity of the fluid increases when shear is applied. For example:
Quicksand
Cornflour and water
Silly putty
Pseudoplastic - Pseudoplastic is the opposite of dilatant; the more shear applied, the less viscous it becomes. For example:
Ketchup
Viscosity changes in respect to the amount of shear or stress applied to the fluid.
Rheopectic - Rheopectic is very similar to dilatant in that when shear is applied, viscosity increases. The difference here, is that viscosity increase is time-dependent. For example:
Gypsum paste
Cream
Thixotropic - Fluids with thixotropic properties decrease in viscosity when shear is applied. This is a time dependent property as well. For example:
Paint
Cosmetics
Asphalt
Glue
It's important to fully understand the properties of the fluids you're transferring, mixing, or pumping because viscosity plays a major role in sizing and selecting equipment. Understanding how it reacts to shear will help you properly size and select all the equipment it touches.
MAJOR IMPACTS OF VISCOSITY ON FLUIDS
ReplyDelete1. Mixing of the components does not occur properly as the speed of
the impeller is much slower due the high viscosity.
2. Formation of physical and chemical gradients in broth.
3. Improper mixing affects the mass transfer processes.
4. Due to change in broth behaviour difficulty is seen in scale up
studies
18MMB029
18mbt025
ReplyDeleteWhat is Rheology?
Rheology is generally defined as the study of the flow of fluid and the subsequent deformation of matter as a result of flow. The rheological characteristics of materials directly affect the way that they should be handled and processed. Specifically, the rheological properties determine: How the material should be mixed,What tools should be used to disperse the material, The way that coatings settle, The material's shear rate, or the rate that the material can be deformed, How the material flows into space etc.
Rheological traits are affected by certain inherent qualities of the material, namely:
-Resin, which affects the viscosity and the surface wetting of the material
-Formulation of the material with its additives
-Temperature, which directly affects the viscosity of the material
-Shear, or the way that a material reacts to force.
How is Rheology Classified?
Rheology has developed two classes of liquids: Newtonian and Non-Newtonian fluids.
Newtonian Fluids
Newtonian fluids are those which follow Newton's hypothesis, and they are considered to be perfectly viscous. This is because the ratio between the shear rate and shear stress are constant, or in other words, the viscosity of the liquid remains constant at all possible shear rates for a given temperature. Pure water, oils, and organic solvents are all examples of Newtonian liquids. Because of their purity and the lack of dispersion, Newtonian fluids are much easier to measure. Unfortunately, however, they are not very common.
Non-Newtonian Fluids
Most liquids are non-Newtonian fluids, meaning they do not have a constant ratio between their shear rate and shear stress. These fluids can be unpredictable in how their shear stress changes according to the shear rate: as the shear rate increases, the shear stress can either increase or decrease, depending on the fluid's own characteristics. As a result, the viscosity of the material is highly variable. Non-Newtonian fluids will have apparent viscosities that depend entirely on the specific experimental conditions, and when working with these materials, it is important to be completely clear as to what these parameters are.
Non-Newtonian fluids are further classified into two groups: power law fluids and time-dependent fluids.
-Power Law Fluids
Power law fluids are categorized based on how the viscosity is affected by the shear. If the viscosity increases as the shear increases, this is a dilatant fluid. Examples of dilatant fluids include candies, sand/water mixtures, and clay slurries.
On the other hand, if the viscosity decreases as the shear increases, this is a pseudoplastic. Pseudoplastics are the most common type of non-Newtonian fluids, and they include inks, mayonnaise, paints, emulsions, and dispersions.
-Time-Dependent Fluids
The viscosity of time-dependent fluids will change over time. If the viscosity increases as time increases, this is a rheopectic fluid. Fluids that include solvents that evaporate, such as adhesives or coatings will fall into this category.As time increases, however, other fluids will decrease in viscosity if the shear rate is held constant. These are thixotropic, and they can return to their original internal structure before the shear. As such, these materials sometimes give a false high viscosity rate when first measured, because some of the fluid has retained viscosity while in other parts of the fluid, the viscosity has decreased significantly.
18mbt025
ReplyDeleteOn what basis Rheological properties can be measured?
Rheological Properties can be measured on the basis of:
1.Viscosity
Viscosity if often measured via rotating spindle instruments. The instrument will calculated the amount of force (torque) it needs to turn a spindle that is in a sample of the liquid at a specific speed (RPM). The instrument's computer will then use the measured of "internal resistance" of the fluid (measured from the force it needed to apply to turn the spindle) to give the viscosity of the fluid.
2.Thixotropic Index
The thixotropic index is also known as the Shear Thinning Index (STI), and it is used to determine how stiff a material will be. This is determined by measuring the change in the viscosity (the ratio of shear stress and shear rate) as the shear rate is increased and then decreased. Materials are rated on the index scale from a range of 1 to 5, with one being the most high flow fluids, and five being the least.
3.Dispense Rate
The dispense rate of materials is measured by changing the pressure, orifice size, and temperature as the material is dispersed. At these conditions are varied, the amount of of the material that is dispersed will vary. This can be measured and compared.
4.Sag Resistance
Finally, the sag resistance of highly thixotropic products (where the viscosity of the material decreases over time) can be tested as well. This requires a bead of material being applied to a flat surface so that the final flow can be measured.
Q) What is Rheology?
ReplyDeleteAns) Rheology is a branch of physics that deals with the study of the flow of liquid matter and the deformation of solid materials.
• Rheology considers the non-Newtonian fluids that remains viscous or in a semi-solid state and the deformation of solids during the application of a certain amount of force.
•The rheological characteristics of materials directly affect the way that they should be handled and processed. Specifically, the rheological properties determine:
1)How the material should be mixed
2)What tools should be used to disperse the material
3)The way that coatings settle,
4)The material's shear rate, or the rate that the material can be deformed
5)How the material flows into spaces.
•Rheology has developed two classes of liquids:
1) Newtonian
2) Non-Newtonian fluids.
3) Power Law Fluids
4) Time-Dependent Fluids
•There are four characteristics of fluids that can be measured to determine their rheological properties. These are:
1)Viscosity
2)Thixotropic Index
3)Dispense Rate
4)Sag Resistance.
•Rheometers are instruments used to characterize the rheological properties of materials, typically fluids that are melts or solution.
Q.. WHAT IS NEWTONIAN FLUID AND NON-NEWTONIAN FLUID ?
ReplyDeleteANS...Newtonian fluids are described as the flow behavior of fluids with a simple linear relation between shear stress [mPa] and shear rate [1/s]. This relationship is now known as Newton's Law of Viscosity, where the proportionality constant η is the viscosity [mPa-s] of the fluid.
example:Some examples of Newtonian fluids include water, organic solvents, and honey. For those fluids viscosity is only dependent on temperature.
An exception to the rule is Bingham plastics, which are fluids that require a minimum stress to be applied before they flow.
Newtonian fluids are normally comprised of small isotropic (symmetric in shape and properties) molecules that are not oriented by flow. However, it is also possible to have Newtonian behavior with large anisotropic molecules
NON-NEWTONIAN:
In reality most fluids are non-Newtonian, which means that their viscosity is dependent on shear rate (Shear Thinning or Thickening) or the deformation history (Thixotropic fluids). In contrast to Newtonian fluids, non-Newtonian fluids display either
a non-linear relation between shear stress and shear rate.
Non-Newtonian behavior of fluids can be caused by several factors, all of them related to structural reorganization of the fluid molecules due to flow. In polymer melts and solutions, it is the alignment of the highly anisotropic chains what results in a decreased viscosity. In colloids, it is the segregation of the different phases in the flow that causes a shear thinning behavior.
Q. WHAT IS RHEOLOGY ?
ReplyDeleteANS... Rheology is a branch of physics that deals with the study of the flow of liquid matter and the deformation of solid materials. Rheology considers the non-Newtonian fluids that remains viscous or in a semi-solid state and the deformation of solids during the application of a certain amount of force.
: Some examples of rheological measurement include:
Visocity profiling of non-Newtonian fluids that changes their shape and flow when a force is applied to it
Stabilizing the dispersion rate of a non-Newtonian fluid
Determining the thixotropy of paints and coatings
Determining the complete curing of particular paints and coatings so as to understand their bonding strength
A rheometer is a device used to measure fluid flow and solid deformation. When a viscous fluid or a semi-solid state fluid such as a slurry or fluid suspension flows due to an applied force, a rheometer measures the flow or the movement of this semi-solid state fluid and the amount of deformation it undergoes.
(ROLL NO. 18MBT012)
What is Newtonian and Non-Newtonian fluids ?
ReplyDeleteNewton’s law of viscosity :-
It states that applied shear stress varies linearly with the rate of deformation.
Newtonian Fluids - The fluids which obey Newton’s law of viscosity are known as Newtonian Fluids .
Example :- Air, Water , Kerosene
Non-Newtonian Fluids :- Fluids which do not follow Newton’s law are called non-newtonian fluids .
- They are also known as Rheological fluids and their study is called RHEOLOGY .
Example - ketchup , toothpaste , honey
18mbt030
What is Newtonian and Non-Newtonian fluids ?
ReplyDeleteANS:- All fluids can be broken down into two basic types, Newtonian, and non-Newtonian.
NEWTONIAN FLUIDS
A Newtonian fluid's viscosity remains constant, no matter the amount of shear applied for a constant temperature.These fluids have a linear relationship between viscosity and shear stress.
Examples:
Water
Mineral oil
Gasoline
Alcohol
NON-NEWTONIAN FLUIDS
When shear is applied to non-Newtonian fluids, the viscosity of the fluid changes. The behavior of the fluid can be described one of four ways:
Dilatant - Viscosity of the fluid increases when shear is applied. For example:
Quicksand
Cornflour and water
Pseudoplastic - Pseudoplastic is the opposite of dilatant; the more shear applied, the less viscous it becomes.
For example:
Ketchup
Rheopectic - Rheopectic is very similar to dilatant in that when shear is applied, viscosity increases. The difference here, is that viscosity increase is time-dependent. For example:
Gypsum paste
Cream
Thixotropic - Fluids with thixotropic properties decrease in viscosity when shear is applied. This is a time dependent property as well. For example:
Paint
Cosmetics
Asphalt
Glue
18MMB013
Que - What is Newtonion and non Newtonion fluids?
ReplyDeleteAns-Newton's law of viscosity states that shear stress is directly proportional to velocity gradient
NEWTONIAN FLUID - It obeys newton's law of viscosity. A Newtonian fluid viscosity remains constant, no matter the amount of shear applied for a constant temperature.. These fluids have a linear relationship between viscosity and shear stress.
Water, oil, gasoline, alcohol and even glycerin are examples of Newtonian fluids
NON NEWTONIAN FLUID'S - are the opposite of Newtonian fluids. When shear is applied to non-Newtonian fluids, the viscosity of the fluid changes. They do not obey newton's law of viscosity.
Examples slurries, suspensions, gels and colloids.
18MBT033
What are Newtonian and Non-Newtonian Fluids?
ReplyDeleteA Newtonian fluid is a fluid in which the viscous stresses arising from its flow, at every point, are linearly proportional to the local strain rate - the rate of change of its deformation over time. That is equivalent to saying those forces are proportional to the rates of change of the fluid's velocity vector as one moves away from the point in question in various directions.
More precisely, a fluid is Newtonian only if the tensors that describe the viscous stress and the strain rate are related by a constant viscosity tensor that does not depend on the stress state and velocity of the flow. If the fluid is also isotropic (that is, its mechanical properties are the same along any direction), the viscosity tensor reduces to two real coefficients, describing the fluid's resistance to continuous shear deformation and continuous compression or expansion, respectively.
Examples: Water, Mineral oil, Gasoline, Alcohol.
A non-Newtonian fluid is a fluid that does not follow Newton's law of viscosity , i.e. constant viscosity independent of stress. In non-Newtonian fluids, viscosity can change when under force to either more liquid or more solid. Ketchup, for example, becomes runnier when shaken and is thus a non-Newtonian fluid. Many salt solutions and molten polymers are non-Newtonian fluids, as are many commonly found substances such as custard , honey , toothpaste , starch suspensions, maizena , paint , blood , and shampoo .
18MMB015
About Rheology...
ReplyDeleteThe word rheology comes from the Greek word "rheos," translated to English as "stream," and it might remind some of the Spanish word "rio." This is important to understand the origin of the word because rheology is the study of the flow (like a stream or a river) and the subsequent deformation of matter as a result of flow. The rheological characteristics of materials directly affect the way that they should be handled and processed. Specifically, the rheological properties determine:
•How the material should be mixed
•What tools should be used to disperse the material
•The way that coatings settle,
•The material's shear rate, or the rate that the material can be deformed
•How the material flows into spaces.
Rheology has developed two classes of liquids: Newtonian and Non-Newtonian fluids.
Newtonian Fluids:
Newtonian fluids are those which follow Newton's hypothesis, and they are considered to be perfectly viscous. This is because the ratio between the shear rate and shear stress are constant, or in other words, the viscosity of the liquid remains constant at all possible shear rates for a given temperature. Pure water, oils, and organic solvents are all examples of Newtonian liquids. Because of their purity and the lack of dispersion, Newtonian fluids are much easier to measure. Unfortunately, however, they are not very common.
Non-Newtonian Fluids:
Most liquids are non-Newtonian fluids, meaning they do not have a constant ratio between their shear rate and shear stress. These fluids can be unpredictable in how their shear stress changes according to the shear rate: as the shear rate increases, the shear stress can either increase or decrease, depending on the fluid's own characteristics. As a result, the viscosity of the material is highly variable. Non-Newtonian fluids will have apparent viscosities that depend entirely on the specific experimental conditions, and when working with these materials, it is important to be completely clear as to what these parameters are.
18MMB015
What are Newtonian and Non-newtonian fluids? Ans:- Newton's law of Viscosity:- it states that applied shear stress varies linearly with the rate of deformation. NEWTONIAN FLUIDS:- the fluids which obey Newton's law of Viscosity are known as Newtonian Fluids.examples :-Air ,Water,Glycerine,Kerosene etc. NOn- Newtonian Fluids:- fluids which do not follow Newton's law are called NOn- Newtonian Fluids.they are also known as Rheological fluids and their study is called Rheology. Newtonian fluids:- a Newtonian fluids viscosity remains constant no matter the amount of shear applied for a constant temperature these fluids have a linear relationship between viscosity and shear stress. Non - Newtonian fluids NOn- Newtonian fluids are the opposite of Newtonian fluids. When shear is applied to non -newtonian fluids ,the viscosity of the fluid changes .The behaviour of the fluid can be described one of four ways 1) Dilatant. 2) pseudoplastic. 3) Rheopectic. 4) Thixotropic. Roll no:- 18mmb011.
ReplyDeleteMethods used for measurement of Kala. Ans:- it is extremely difficult to measure both 'kL' and 'a' in a fermentation and, therefore,the two terms are generally combined in the term KLa ,known as the volumetric mass- transfer coefficient. The volumetric mass-transfer coefficient is used as a measure of the aeration capacity of a fermenter. The larger the kLa ,the higher the aeration capacity of the system. The determination of KLa value is done by:- 1) sulphite oxidation technique. 2) Gassing out techniques :- static gassing out method ,Dynamic gassing out method.3) oxygen balance technique. The factors affecting KLa values in fermentation vessels. 1) the air flow rate employed in vessels 2) the degree of agitation inside vessels 3) the presence of antifoam agents. Roll no:- 18mmb011.
ReplyDeleteQ) Name the methods used for measurement of KLa.
ReplyDeleteAns) Mainly 5 methods used for KLa measurement
1. Chemical Method:
•The chemical method is known as the sulfite oxidation method.
•It involves the determination of the maximum rate of oxidation of sodium sulfite to sodium sulfate in the presence of c0so4 or CuSO4 catalyst, in which there is no back pressure of dissolved oxygen.
2. Dynamic Differential Gassing-Out (DDGO) Method:
•This method, developed by Bandyopadhyay et al., is based on following the DO trace during a brief interruption of aeration in the fermentation system. Only a fast-response, sterilizable DO probe is needed to obtain the necessary data.
•Advantage: it measures KLa in the actual fermentation system so that the number of assumptions required are less.
It is a simple method.
3. Oxygen Balance (OB) Method:
•oxygen balance over the whole system is the best method for evaluation of KLa in fermenters, because no assumption need be made on the effects of cell, surface active agents, viscosity, and forth. Based on the oxygen balance concept, Mukhopadhyay and Ghose developed a linear mathematical correlation between DO concentration and the proportion of oxygen in inlet and exit air of laboratory fermenter from which KLa can be determined very easily and rapidly.
4. Enzymic Method (GGO):
•Based on the Heineken theory, Linek and his associates ‘ developed a dynamic method to determine KLa in a fermenter using the glucose-glucose oxidase (GGO) system. Assuming absorption of oxygen in the liquid phase as the first-order reaction as well as perfect mixing conditions, the rate of oxygen absorption in the GGO system in a mechanically agitated dispersion (MAD) of gas.
5.Dynamic Integral Gassing-Out (DIGO) Method:
Q) Types of steel and their composition
ReplyDeleteAns) According to the American Iron & Steel Institute (AISI), Steel can be categorized into four basic groups based on the chemical compositions:
1)Carbon Steel
2)Alloy Steel
3)Stainless Steel
4)Tool Steel
There are many different grades of steel that encompass varied properties. These properties can be physical, chemical and environmental.
All steel is composed of iron and carbon. It is the amount of carbon, and the additional alloys that determine the properties of each grade.
1) Carbon steel: Carbon steels contain trace amounts of alloying elements and account for 90% of total steel production. Carbon steels can be further categorized into three groups depending on their carbon content:
•Low Carbon Steels/Mild Steels contain up to 0.3% carbon
•Medium Carbon Steels contain 0.3-0.6% carbon
•High Carbon Steels contain more than 0.6% carbon
2) Alloy Steels: Alloy steels contain alloying elements (e.g. manganese, silicon, nickel, titanium, copper, chromium, and aluminum) in varying proportions in order to manipulate the steel's properties, such as its hardenability, corrosion resistance, strength, formability, weldability or ductility.
3) Stainless Steels: Stainless steels generally contain between 10-20% chromium as the main alloying element and are valued for high corrosion resistance. With over 11% chromium, steel is about 200 times more resistant to corrosion than mild steel.
These steels can be divided into three groups based on their crystalline structure:
•Austenitic: Austenitic steels are non-magnetic and non-heat-treatable, and generally contain 18% chromium, 8% nickel and less than 0.8% carbon.
•Ferritic: Ferritic steels contain trace amounts of nickel, 12-17% chromium, less than 0.1% carbon, along with other alloying elements, such as molybdenum, aluminum or titanium. These magnetic steels cannot be hardened by heat treatment but can be strengthened by cold working.
•Martensitic: Martensitic steels contain 11-17% chromium, less than 0.4% nickel, and up to 1.2% carbon.
4) Tool Steels
Tool steels contain tungsten, molybdenum, cobalt and vanadium in varying quantities to increase heat resistance and durability, making them ideal for cutting and drilling equipment.
Steel products can also be divided by their shapes and related applications:
•Long/Tubular Products:include bars and rods, rails, wires, angles, pipes, and shapes and sections.
•Flat Products:include plates, sheets, coils, and strips. These materials are mainly used in automotive parts, appliances, packaging, shipbuilding, and construction.
•Other Products:include valves, fittings, and flanges and are mainly used as piping materials.
Q)What is Newtonian fluid and Non-Newtonian fluid?
ReplyDeleteAns) Newtonian fluids: Newtonian fluids are those which follow Newton's hypothesis, and they are considered to be perfectly viscous.
•This is because the ratio between the shear rate and shear stress are constant, or in other words, the viscosity of the liquid remains constant at all possible shear rates for a given temperature.
•Pure water, oils, and organic solvents are all examples of Newtonian liquids. Because of their purity and the lack of dispersion, Newtonian fluids are much easier to measure.
Non-Newtonian Fluids:
•Most liquids are non-Newtonian fluids, meaning they do not have a constant ratio between their shear rate and shear stress.
•These fluids can be unpredictable in how their shear stress changes according to the shear rate: as the shear rate increases, the shear stress can either increase or decrease, depending on the fluid's own characteristics.
•As a result, the viscosity of the material is highly variable.
•Non-Newtonian fluids will have apparent viscosities that depend entirely on the specific experimental conditions, and when working with these materials, it is important to be completely clear as to what these parameters are.
Non-Newtonian fluids are further classified into two groups: power law fluids and time-dependent fluids.
1) Power Law Fluids
•Power law fluids are categorized based on how the viscosity is affected by the shear. If the viscosity increases as the shear increases, this is a dilatant fluid.
•Examples of dilatant fluids include candies, sand/water mixtures, and clay slurries.
•On the other hand, if the viscosity decreases as the shear increases, this is pseudoplastic. Pseudoplastics are the most common type of non-Newtonian fluids, and they include inks, mayonnaise, paints, emulsions, and dispersions.
2)Time-Dependent Fluids:
•The viscosity of time-dependent fluids will change over time. If the viscosity increases as time increases, this is a rheopectic fluid. •Fluids that include solvents that evaporate, such as adhesives or coatings will fall into this category.
•As time increases, however, other fluids will decrease in viscosity if the shear rate is held constant. These are thixotropic, and they can return to their original internal structure before the shear. As such, these materials sometimes give a false high viscosity rate when first measured, because some of the fluid has retained viscosity while in other parts of the fluid, the viscosity has decreased significantly.
Q.1) How is the pathways basically discovered?
ReplyDeleteAns: One way that can be used is radioactive tracer.We can create a radioactive version of a compound that we are interested in and feed this into the biochemical pathway some how. eg feed it to cells. When a labelled chemical compound undergoes chemical reactions one or more of the products will contain the radioactive label. Analysis of what happens to the radioactive isotope provides detailed information on the mechanism of the chemical reaction.
Q.2) What are Newtonian and Non-Newtonian fluids? What is the importance of Rheology?
Ans: In Newtonian fluids,viscocity remains constant no matter the amount of shear applied for a constant temperature.The viscocity of the fluid is directly proportional to the shear stress.
Example: water, gasoline,alcohol and mineral oil.
Non-Newtonian fluids: In these fluids when the shear stress is applied the viscocity of the fluid changes.
Examples: Paints, cosmetics, glue, ketchup, etc.
IMPORTANCE OF RHEOLOGY:
It is important to test the behaviour of mineral slurries as they are indicative of the level of inter-particle interaction or aggregation. It is also taken into consideration for understanding of inter-particle interactions and potentially of bubble–particle interactions in mineral slurries.
Q.3) Why doesn't the detergent remove all the stains completely like: pickle stains?
Ans: Detergents contain lipases. Lipases are active in
solution and at the water-oil interface. The lipase activity depends on washing solution composition, temperature and pH,
washing time and fabric type.
18MBT001
Why Hydrogen gas cannot be used as fuel despite being the purest and pollution free?
ReplyDeleteIt is because hydrogen is a highly combustible and it reacts explosively when it comes in contact with air. And hence as a result, storing of the hydrogen gas is difficult and is dangerous at the same time. So, even though hydrogen has the highest calorific value, it is not used as a domestic fuel.
Q: Are there any microbiological ways for producing hydrogen gas?
ReplyDeleteA: Yes, hydrogen gas can be produced by microbiological methods.
This can be performed by direct biophotolysis and indirect biophtolysis.
# Direct biophotolysis
Cells of certain algae eg. Chlamydomonas reinhardtii, chlorella fusca) or cyanobacteria are capable to split water into molecular hydrogen and oxygen under illumination. This process require absolutely anaerobic conditions.
# Indirect biophotolysis
This process can be performed with certain cyanobacteria (eg. Anabeana variabilis). This method is difficult to perform in industry because of periodicity of process.
The hydrogen yields generated by either direct or indirect photolysis are unfortunately very low in comparison with other fermentative methods.
~ Photofermentation
This process is based on decomposition of organic compounds to hydrogen in the presence of both oxygen and nitrogen but in presence of photosynthetic bacteria under illumination. The main advantage of this process rely on the high yield of hydrogen while transforming organic compounds to H2 and CO2.
~ Dark fermentation
This process occur in the absence of light. Anearobic microorganisms are generating hydrogen while transforming biodegradable substances under oxygen free conditions. But hydrogen is not the only gaseous product of this process. Carbon dioxide, methane, hydrogen sulfide can be found. Final amount of generated hydrogen depends on many factors including type, and concentration of the substrate, pH value, substrate to innoculum ratio, etc. The relatively high rate of hydrogen production is the important factor influencing possible industrial applications.
~Hybrid systems
1) one step hybrid system
2) two step hybrid system
This process uses useless and difficult to operate substrates in the photofermentation process. The advantage of one step hybrid systems is the high rate and much higher yield in hydrogen production than dark fermentation.
The natural organic substrates and wastes that can be used in two step hybrid system. One mole of glucose theoretically generates 4 moles of hydrogen in dark fermentation, whereas acetic acid is the only side product. In practice, dark fermentation of liquid wastes generates much lower amounts of hydrogen. The hybrid systems are much more efficient.
Also modifications can be done by genetic engineering. The main idea of modification rely on implantation of other genes into the bacterial strains containing hydrogenase.eg.in Ecoli for producing hydrogen.
Q: Why hydrogen gas cannot be used as fuel eventhough it is the purest form?
ReplyDeleteA: Hydrogen can be a possible replacement for conventional gasoline and diesel fuel. But you know that each and every fuel has it's own advantages and disadvantages.
-First of all, hydrogen is a gaseous fuel. We know from basic physics that gases are less dense i.e. they occupy more volume. So, hydrogen requires a large fuel tank for storage.
-Unlike other gases, hydrogen is not readily available in the atmosphere. It requires processes like electrolysis and steam reforming for production. The main challenge is, that how efficiently hydrogen can be extracted from these processes.
-
hydrogen is a highly combustible and it reacts explosively when it comes in contact with air (oxygen).
What is Rheology and its types?
ReplyDeleteAnd: Rheology is the study of flow and deformation of materials under applied forces which is routinely measured using a rheometer. The measurement of rheological properties is applicable to all materials from fluids such as dilute solutions of polymers and surfactants through to concentrated protein formulations, to semi-solids or solid polymers as well as asphalt.
Types of fluid:
Newtonian fluid:
A real fluid, in which shear stress in directly proportional to the rate of shear strain or velocity gradient, is known as a Newtonian fluid.
Fluids that obey Newton’s law of viscosity are known as Newtonian Fluids. For a Newtonian fluid, viscosity is entirely dependent upon the temperature and pressure of the fluid.
Examples: water, air, emulsions
Non Newtonian fluid:
A real fluid, in which shear stress in not directly proportional to the rate of shear strain or velocity gradient, is known as a Non Newtonian fluid.
Fluids that do not obey Newton’s law of viscosity are non-Newtonian fluids.
Examples: Flubber, Oobleck (suspension of starch in water).
SHRUTI SRIVASTAVA (18mbt034)
ReplyDeleteRheology is the study of flow and deformation of materials under applied forces which is routinely measured using a rheometer. The measurement of rheological properties is applicable to all materials from fluids such as dilute solutions of polymers and surfactants through to concentrated protein formulations, to semi-solids or solid polymers as well as asphalt.
Types of fluid:
Newtonian fluid:
A real fluid, in which shear stress in directly proportional to the rate of shear strain or velocity gradient, is known as a Newtonian fluid.
Fluids that obey Newton’s law of viscosity are known as Newtonian Fluids. For a Newtonian fluid, viscosity is entirely dependent upon the temperature and pressure of the fluid.
Examples: water, air, emulsions
Non Newtonian fluid:
A real fluid, in which shear stress in not directly proportional to the rate of shear strain or velocity gradient, is known as a Non Newtonian fluid.
Fluids that do not obey Newton’s law of viscosity are non-Newtonian fluids.
Examples: Flubber, Oobleck (suspension of starch in water).
Microbiological ways for hydrogen production.
ReplyDeleteDirect biophotolysis.
Indirect biophotolysis.
Photofermentation.
Dark fermentation.
Hybrid systems.
Hydrogen is a clean fuel. It is an energy carrier that can be used for a broad range of applications. Also it could serve as a possible substitute to liquid and fossil fuels. At standard temperature and pressure, hydrogen is a nontoxic, nonmetallic, odorless, tasteless, colorless, and highly combustible diatomic gas with the molecular formula H2.
Its storage is important because it has wide range of applications. They range from stationary power, portable power to transportation, etc. Also it has the highest energy per mass of any fuel. However, its low ambient temperature density results in a low energy per unit volume, therefore requiring the development of advanced storage methods that have potential for higher energy density.
Hydrogen can be stored physically as either a gas or a liquid. Storage of hydrogen as a gas typically requires high-pressure tanks (350–700 bar [5,000–10,000 psi] tank pressure). Storage of hydrogen as a liquid requires cryogenic temperatures because the boiling point of hydrogen at one atmosphere pressure is −252.8°C. Hydrogen can also be stored on the surfaces of solids (by adsorption) or within solids (by absorption). Hydrogen is considered an alternative fuel. It is due to its ability to power fuel cells in zero-emission electric vehicles, its potential for domestic production, and the fuel cell's potential for high efficiency. Hydrogen can also serve as fuel for internal combustion engines. The energy in 2.2 pounds (1 kilogram) of hydrogen gas contains about the same as the energy in 1 gallon (6.2 pounds, 2.8 kilograms) of gasoline.
Advantages: It is readily available, it doesn’t produce harmful emissions, it is environmentally friendly, it can be used as fuel in rockets, it is fuel efficient, it is renewable.
Eventhough it is the cleanest fuel it is not widely used as it has the following disadvantages
It is expensive, it is difficult to store, it is highly flammable - Since it is a very powerful source of fuel, hydrogen can be very flammable. Hydrogen gas burns in air at very wide concentrations between 4 and 75 percent.
Uditi Raval
18MMB023
Cellulolytic microorganisms.
ReplyDeleteCellulases are a consortium of free enzymes which comprise of endoglucanases, exoglucanases and cellobiases which are found in many of the 57 glycosyl hydrolase families. Many fungi capable of degrading cellulose synthesize large quantities of extracellular cellulases that are more efficient in depolymerising the cellulose substrate. Most commonly studied cellulolytic organisms include fungal species: Trichoderma, Humicola, Penicillium, and Aspergillus. Among Trichoderma spp., T. harzianum and T. koningii have been studied. Trichoderma viride has the highest cellulolytic activity. Many cellulases produced by bacteria appear to be bound to the cell wall and are unable to hydrolyze native lignocellulose preparations to any significant extent. A wide variety of Gram-positive and Gram-negative species have been reported to produce cellulose, including Clostridium thermocellum, Streptomyces spp., Ruminococcus spp., Pseudomonas spp., Cellulomonas spp., Bacillus spp., Serratia, Proteus, Staphylococcus spp., and Bacillus subtilis.
Uditi Raval
18MMB023
Q.1) List of cellulolytic microorganisms.
ReplyDeleteAns: Many microorganisms have been reported with cellulosic activities including many bacterial and fungal strains both aerobic and anaerobic. Chaetomium, Fusarium Myrothecium, Trichoderma. Penicillium, Aspergillus,etc.Cellulolytic bacterial species include Trichonympha, Clostridium, Actinomycetes, Bacteroides succinogenes, Butyrivibrio fibrisolvens, Ruminococcus albus, and Methanobrevibacter ruminantium.
Q.2) Microbial ways of hydrogen production?
Ans: Hydrogen production can be done in various ways:
Dark Fermentation
It is a fermentation-based system,in which microorganisms, such as bacteria, break down organic matter to produce hydrogen. The organic matter can be refined sugars, raw biomass sources such as corn stover, and even wastewater.
Direct Hydrogen Fermentation
In direct hydrogen fermentation, the microbes produce the hydrogen themselves. These microbes can break down complex molecules through many different pathways, and the byproducts of some of the pathways can be combined by enzymes to produce hydrogen.
Microbial Electrolysis
Microbial electrolysis method generally involves the use of microbial electrolysis cells (MECs). MECs are devices that harness the energy and protons produced by microbes breaking down organic matter, combined with an additional small electric current, to produce hydrogen. This technology is very new.
Hydrogen is not used as a fuel even being the cleaner gas because of it's highly combustible nature, it reacts explosively when it comes in contact with air.Due to this it's storage becomes difficult. Hydrogen also has the highest calorific value.
Ankita Oza
18MBT001
Why hydrogen fuel cell is not widely used for energy production?
ReplyDeleteIt is not used as a widely used source because hydrogen production from hydrocarbons or water requires more energy than recovered by the fuel cell. The cost of storage and catalyst is also high.
18 mbt027
Question:- List Of Cellulolytic microorganisms.
ReplyDeleteAns:-
▪Cellulolytic bacterial species include:-
Trichonympha,Clostridium,
Actinomycetes, Bacteroides ,
Butyrivibrio fibrisolvens,
Ruminococcus albus,
Methanobrevibacter ruminantium
Pseudomonas,Streptomyces, Rhodococcus, Stentrophomonas, Variovorax, Serratia, Janthinobacterium.
▪Cellulolytic fungal species includes :-
Penicillum, Mortierella, Tolypocladium,
Paecilomyces, Acremonium, Fusarium,
Volutella, Hypocrea, Neonectria,
Mucor, Aureobasidium, Arthtinium .
18MMB010
DeleteQ1.) Why hydrogen cannot be used as a fuel?
ReplyDeleteThe major reason remains to be the fact that it is highly combustible and when reacts with air gives an explosive reaction. Hydrogen is hard to store. You need high pressure tanks with special liners. Also, even at high pressure the specific energy by volume is low. Hydrogen doesnot exist by itself on earth. It is always bound to one material or another and thus it takes a large amount of energy to separate hydrogen from whatever it is bound to.
Q2.)Microbiological ways of producing hydrogen:
1.Dark-fermentative hydrogen production- It occurs under anoxic or anaerobic conditions (i.e., in the absence of O2 as an electron acceptor). The key pathway is the breakdown of carbohydrate rich substrates by bacteria ( like, Clostridia spp., and enterobacter spp) to H2 and other intermediate products such as volatile fatty acids (VFA's) and alcohols.
2. Photofermentation- It is carried out by nonoxygenic photosynthetic bacteria that use sunlight and biomass to produce hydrogen. Purple non-sulfur (PNS) and green sulfur (GS) bacteria such as Rhodobacter spheroids and Chlorobium vibrioforme, respectively, are capable of producing hydrogen gas by using solar energy and reduced compounds.
3. Microbial electrolysis cell (MEC)- represents an alternative electrically driven H2 production process, which facilitates the conversion of electron equivalents in organic compounds to H2 gas by combining microbial metabolism with bioelectrochemical reactions. Low-energy consumption compared to conventional water electrolysis, high product (H2) recovery, and substrate degradation than the dark fermentation process are some of the potential benefits that make MEC an alternate process.
4. Direct biophotolysis- refers to sustained hydrogen evolution under light irradiation. Cyanobacteria are potential microbial species for hydrogen production via direct biophotolysis [27]. By using nitrogenase and/or bi-directional hydrogenase, both heterocystous nitrogen-fixing strains and unicellular non-nitrogen-fixing strains are able to evolve hydrogen under special conditions
SURABHI JOSHI
18MMB027
CELLULOLYTIC MICROORGANISMS
ReplyDeleteMany cellulose degrading microorganisms secrete cocktails of numerous lignocellulolytic enzymes viz. cellobiohydrolase (CBH), endo-1, 4-β-D-glucanase (EG) and β-glucosidase (BG) which acts synergistically to degrade lignocellulosic biomass completely . The cellulose utilizing population includes aerobic and anaerobic mesophilic bacteria, filamentous fungi, thermophilic and alkaliphilic bacteria, actinomycetes and certain protozoa.
Rumen Cellulolytic Protozoa-
Enoploplastron triloricatum, Eudiplodinium maggii, Diploplastron afine, Epidinium ecaudatum caudatum, Diplodinium monacanthum and Diplodinium pentacanthum.
Cellulolytic Bacteria-
Clostridium, Cellulomonas, Cellulosimicrobium,Thermomonospora, Ruminococcus, Erwinia, Bacteriodes, Acetovibrio, Streptomyces,Microbispora, Fibrobacter, and Paenibacillus have been observed to produce different kinds of cellulose. Others include Bacillus brevis, Bacillus alcalophilus, Xanthomonas, Micrococcus, Brucella spp., Pseudomonas stutzeri.
Cellulolytic Fungi-
Trichoderma, Aspergillus, Penicillium, Phanerochaete, Fomitopsis, Monocillium and Fusarium, Acremonium, Alternaria, Drechslera, Monacrosporium.
SURABHI JOSHI
18MMB027
Q.1 What is the difference between Methods and Techniques?
ReplyDeleteAns. By the meaning of verbal use both the words are same and are use interchangeably in many fields.
If we go by dictionary meanings, technique means a systematic procedure, formula, or a routine by which a task is accomplished.
On the other hand, method is defined as a habitual, logical, or prescribed practice or systematic process of achieving certain end results with accuracy and efficiency, usually in a preordained sequence of steps.
However, when the method is systematic and based upon logic, it is sometimes referred to as a scientific method which comes even closer to technique.
If we take an example in a layman language , One wants to cook a dish and finds a protocol on the internet and makes the dish. This is the method that he has followed from the internet by which he could achieve his goal of making the particular dish. In this he has added the certain ingredients.
If he makes the different dish with same ingredients then it is called a technique.
I've forgotten to mention my Roll call
DeleteIt is 18MBT010
Q.1 Why Hydrogen is not used as a fuel even-though having highest calorific value
ReplyDeleteAns. Hydrogen is abundantly present in the nature. It is highly flammable in pure form but in air it is present in the complex with other gases with make it inactive.
- It's calorific value is 150 KJ/gram ,which is highest among all the gases.
Q.2 How the hydrogen is produced with the help of microorganism?
Fermentation industry to produce Hydrogen gas.
Ans. A) With the help of microorganisms, the ability of bacteria
to convert the biomass into a product is called "Microbial
Biomass Conversion."
-The organic matter can be refined sugars, raw biomass
sources such as corn stover, and even wastewater. Because
no light is required, these methods are sometimes called
"dark fermentation" methods.
-Production of hydrogen by anaerobes, facultative
anaerobes, aerobes, methylotrophs, and photosynthetic
bacteria is possible. Anaerobic Clostridia are potential
producers and immobilized C. butyricum produces 2 mol
H2/mol glucose at 50% efficiency. Spontaneous production
of H2 from formate and glucose by immobilized Escherichia
coli showed 100% and 60% efficiencies, respectively.
-Their efficiency and production yield differ from sugar
to sugar and also on the different conditions.
Cyanobacteria , viz., Anabaena, Synechococcus, and
Oscillatoria sp., have been studied for photo-production
of H2.
B) Microbial electrolysis cells (MECs) are devices that
harness the energy and protons produced by microbes
breaking down organic matter, combined with an additional
small electric current, to produce hydrogen. This
technology is very new, and researchers are working on
improving many aspects of the system, from finding lower-
cost materials to identifying the most effective type of
microbes to use.
18mbt025
ReplyDeleteQuestion: Why hydrogen is not used as a fuel?
Hydrogen is not used as a domestic fuel, even after having the highest calorific value, because-
a. It is neither cheap nor easily available/abundant.
Availability: unlike other gases, hydrogen is not readily available in the atmosphere. It requires processes like electrolysis and steam reforming for production. The main challenge is, that how efficiently hydrogen can be extracted from these processes.
b. It is highly explosive.
c. It does not burn at a slow rate (undergoing controlled combustion).
d. It is not easy to store.
Storage: gases are less dense i.e. they occupy more volume. So, hydrogen requires a large fuel tank for storage
Hydrogen storage has been a hectic process for engineers who are trying to utilize it in the form of fuel. It has to be compressed to higher pressures or stored in a cryogenic vessel for safety reasons.
Hydrogen is actually used for combustion in rockets and space shuttles were it is stored cryogenically. Even with so much difficulties, hydrogen is preferred because of it's very high energy density and tendency to produce less emissions.
Penicillin History and struggle that people did to make the high scale production.
ReplyDeleteHere, I am sharing an article link of above given topic.
It is an interesting. Must read.
https://www.acs.org/content/acs/en/education/whatischemistry/landmarks/flemingpenicillin.html#top
18MBT010
18mbt025
ReplyDeleteNote on microbial way of producing Hydrogen.
Microbiological ways for hydrogen production.
1.Dark fermentation
In fermentation-based systems, microorganisms, such as bacteria, break down organic matter to produce hydrogen. The organic matter can be refined sugars, raw biomass sources such as corn stover, and even wastewater. Because no light is required, these methods are sometimes called "dark fermentation" methods.
2. Direct biophotolysis
Cells of certain algae eg. Chlamydomonas reinhardtii, chlorella fusca) or cyanobacteria are capable to split water into molecular hydrogen and oxygen under illumination. This process require absolutely anaerobic conditions.
3. Indirect biophotolysis
This process can be performed with certain cyanobacteria (eg. Anabeana variabilis). This method is difficult to perform in industry because of periodicity of process.
The hydrogen yields generated by either direct or indirect photolysis are unfortunately very low in comparison with other fermentative methods.
4. Photofermentation
This process is based on decomposition of organic compounds to hydrogen in the presence of both oxygen and nitrogen but in presence of photosynthetic bacteria under illumination. The main advantage of this process rely on the high yield of hydrogen while transforming organic compounds to H2 and CO2.
5. Hybrid systems
1) one step hybrid system
2) two step hybrid system
This process uses useless and difficult to operate substrates in the photofermentation process. The advantage of one step hybrid systems is the high rate and much higher yield in hydrogen production than dark fermentation.
The natural organic substrates and wastes that can be used in two step hybrid system. One mole of glucose theoretically generates 4 moles of hydrogen in dark fermentation, whereas acetic acid is the only side product. In practice, dark fermentation of liquid wastes generates much lower amounts of hydrogen. The hybrid systems are much more efficient.
Now a days Microbial electrolysis cells (MECs) devices are used that harness the energy and protons produced by microbes breaking down organic matter, combined with an additional small electric current, to produce hydrogen. This technology is very new, and researchers are working on improving many aspects of the system, from finding lower-cost materials to identifying the most effective type of microbes to use.
In microbial electrolysis cells, microbes consume organic matter such as acetic acid, producing electrons (e-) and protons (hydrogen ions, H+). The electrons are passed to an electrode and travel through a wire to the electrode in the cathode section of the MEC. Here, with the help a small added voltage, the protons are combined with the electrons to produce hydrogen gas.
Production of hydrogen by anaerobes, facultative anaerobes, aerobes, methylotrophs, and photosynthetic bacteria is possible. Anaerobic Clostridia are potential producers and immobilized C. butyricum produces 2 mol H2/mol glucose at 50% efficiency. Spontaneous production of H2 from formate and glucose by immobilized Escherichia coli showed 100% and 60% efficiencies, respectively. Enterobactericiae produces H2 at similar efficiency from different monosaccharides during growth. Among methylotrophs, methanogenes, rumen bacteria, and thermophilic archae, Ruminococcus albus, is promising (2.37 mol/mol glucose). Immobilized aerobic Bacillus licheniformis optimally produces 0.7 mol H2/mol glucose.
Excellent productivity (6.2 mol H2/mol glucose) by co-cultures of Cellulomonas with a hydrogenase uptake (Hup) mutant of R. capsulata on cellulose was found. Synechococcus sp. has a high potential for H2 production in fermentors and outdoor cultures. Simultaneous productions of oxychemicals and H2 by Klebseilla sp. and by enzymatic methods were also attempted.
18mbt025
ReplyDeleteExplain stainless steel and steel no. 316.
1. Stainless steel
stainless steel also known as inox steel is generally defined as an steel alloy, with highest percentage contents of iron, chromium, and nickel, with a minimum of 10.5% chromiumcontent by mass and a maximum of 1.2% carbon by mass.Stainless steels are most notable for their corrosion resistance, which increases with increasing chromium content. Addition of molybdenum increase corrosion resistance in reducing acids and against pitting attack in chloride solutions.
Stainless steels are rolled into sheets, plates, bars, wire, and tubing to be used in: cookware, cutlery, surgical instruments, major appliances; construction material in large buildings, such as the Chrysler Building; industrial equipment (for example, in paper mills, chemical plants, water treatment); and storage tanks and tankers for chemicals and food products (for example, chemical tankersand road tankers).
304 Stainless Steel
Grade 304 stainless steel is generally regarded as the most common austenitic stainless steel. It contains high nickel content that is typically between 8 and 10.5 percent by weight and a high amount of chromium at approximately 18 to 20 percent by weight. Other major alloying elements include manganese, silicon, and carbon. The remainder of the chemical composition is primarily iron.
The high amounts of chromium and nickel give 304 stainless steel excellent corrosion resistance. Common applications of 304 stainless steel include:
• Appliances such as refrigerators and dishwashers
• Commercial food processing equipment
• Fasteners
• Piping
• Heat exchangers
316 Stainless Steel
Similar to 304, Grade 316 stainless steel has high amounts of chromium and nickel. 316 also contains silicon, manganese, and carbon, with the majority of the composition being iron. A major difference between 304 and 316 stainless steel is the chemical composition, with 316 containing a significant amount of molybdenum; typically 2 to 3 percent by weight vs only trace amounts found in 304. The higher molybdenum content results in grade 316 possessing increased corrosion resistance.
316 stainless steel is often considered one of the most suitable choices when selecting an austenitic stainless steel for marine applications. Other common applications of 316 stainless steel include:
• Chemical processing and storage equipment.
• Refinery equipment
• Medical devices
• Marine environments, especially those with chlorides present
18mbt025
ReplyDeleteQuestion. Note on mild steel.
Mild steel is the most commonly used steel. It is used in the industries as well in the different everyday objects we use. The mild steel is very important in the manufacturing of metal items. Almost 90% steel products of the world is made up of mild steel because it is the cheapest form of steel.
Mild steel Composition consists of -
carbon 0.16 to 0.18 % (maximum 0.25% is allowable)
Manganese 0.70 to 0.90 %
Silicon maximum 0.40%
Sulfur maximum 0.04%
Phosphorous maximum 0.04%
Mildest grade of carbon steel or mild steel contains a very low amount of carbon - 0.05 to 0.26%
Most Important Mild Steel Properties
• A small amount of carbon makes mild steel to change it properties. Different amount of carbon produces different types of steels. There are small spaces between the iron lattice. Carbon atoms get attached to this spaces and makes it stronger and harder. The harder the steel the lesser the ductility.
• The modulus of elasticity calculated for the industry grade mild steel is 210,000 Mpa. It has a average density of about 7860 kg/m3.
• Mild steel is a great conductor of electricity. So it can be used easily in the welding process.
• Because of its malleability, mild steel can be used for constructing pipelines and other construction materials. Even domestic cookwares are made of mild steel. It is ductile and not brittle but hard.
• Mild steel can be easily magnetized because of its ferromagnetic properties. So electrical devices can be made of mild steel.
• Mild steel is very much suitable as structural steel. Different automobile manufacturers also use mild steel for making the body and parts of the vehicle.
• Mild steel can be easily machined in the lathe, shaper, drillling or milling machine. Its hardness can be increased by the application of carbon.
As per Indian Standard 2062, there are nine mildsteel grades specified.
Fe250 or E250
Fe275 or E275
Fe300 or E300
Fe350 or E350
Fe410 or E410
Fe450 or E450
Fe550 or E550
Fe600 or E600
Fe650 or E650
Cite few examples of lignocellulolytic Microbes.
ReplyDeleteFungi:
Trichoderma, Aspergillus, Penicillium, Phanerochaete, Fomitopsis, Monocillium and Fusarium, Acremonium, Alternaria, Drechslera, Monacrosporium.
Bacteria:
Actinomycetes, Bacteroides ,
Butyrivibrio fibrisolvens,
Ruminococcus albus,
Methanobrevibacter ruminantium
Pseudomonas,Streptomyces, Rhodococcus, Stentrophomonas, Variovorax, Serratia, Janthinobacterium, Clostridium
(They produce lignocellulolytic enzymes i.e., cellobiohydrolase (CBH), endo-1, 4-β-D-glucanase (EG) and β-glucosidase (BG) which acts synergistically to degrade lignocellulosic biomass completely . The cellulose utilizing population includes aerobic and anaerobic mesophilic bacteria, thermophilic and alkaliphilic bacteria, actinomycetes filamentous fungi and certain protozoa.)
Question) Why hydrogen cannot be used as a fuel?
ReplyDeleteAns) Hydrogen has the highest calorific value, it is not used as a domestic fuel.
• Reason behind not using hydrogen as fuel:
1) lt is because hydrogen is a highly combustible and it reacts explosively when it comes in contact with air.
2) Pure hydrogen is very hard to find and can be very expensive to use.
3) Highly Flammable
4) High Cost
5) Storage Issues
•Apart from taking much time to separate the compounds of hydrogen, this element is also a challenge to move and transport.
•Hydrogen storage has been a hectic process for engineers who are trying to utilize it in the form of fuel. It has to be compressed to higher pressures or stored in a cryogenic vessel for safety reasons.
6) Availability
• Hydrogen is not readily available in the atmosphere.
18MBT026 Shreya Poorkar
ReplyDeleteQuestion:- Are there any microbiological ways to produce hydrogen?
Answer:- Production of hydrogen by anaerobes, facultative anaerobes, aerobes, methylotrophs, and photosynthetic bacteria is possible. Anaerobic Clostridia are potential producers and immobilized C. butyricum produces 2 mol H2/mol glucose at 50% efficiency. Spontaneous production of H2 from formate and glucose by immobilized Escherichia coli showed 100% and 60% efficiencies, respectively. Enterobactericiae produces H2 at similar efficiency from different monosaccharides during growth. Among methylotrophs, methanogenes, rumen bacteria, and thermophilic archae, Ruminococcus albus, is promising (2.37 mol/mol glucose). Immobilized aerobic Bacillus licheniformis optimally produces 0.7 mol H2/mol glucose. Photosynthetic Rhodospirillum rubrum produces 4, 7, and 6 mol of H2 from acetate, succinate, and malate, respectively. Excellent productivity (6.2 mol H2/mol glucose) by co-cultures of Cellulomonas with a hydrogenase uptake (Hup) mutant of R. capsulata on cellulose was found. Cyanobacteria, viz., Anabaena, Synechococcus, and Oscillatoria sp., have been studied for photoproduction of H2. Immobilized A. cylindrica produces H2 (20 ml/g dry wt/h) continually for 1 year. Increased H2 productivity was found for Hup mutant of A. variabilis. Synechococcus sp. has a high potential for H2 production in fermentors and outdoor cultures. Simultaneous productions of oxychemicals and H2 by Klebseilla sp. and by enzymatic methods were also attempted. The fate of H2 biotechnology is presumed to be dictated by the stock of fossil fuel and state of pollution in future.
18MBT026
ReplyDeleteQuestion:- Why hydrogen is not used as a fuel?
Answer:- It is used, but not widely.
There are 3 major problems with hydrogen as a vehicle fuel, compared to gasoline.
1 - It takes a lot of energy to produce. You have to run a lot of electricity through water to break it down to hydrogen and oxygen. It can also be recovered from fractionating oil when producing fuels, but it is mixed with other gasses and has to be purified. Then it has to be compressed and cooled. It’s most useful form is liquid hydrogen, giving far more energy content than as a highly compressed gas. The container has to be thick walled and insulated, therefore heavy, and a means has to be made to safely alleviate excess pressure due to boil-off.
2 - You need to transport it from the manufacturing plant to the refueling stations. That means heavy trucks, because a pipeline is unworkable. That is a major safety issue. Propane and LNG have similar safety issues, but are safer to transport than hydrogen.
3 - Hydrogen burns without any color to indicate a fire. This becomes a problem refueling your vehicle, because the slightest leak at the nozzle can catch fire without any notice. You don’t refuel by simply putting the nozzle in the filler tube. There has to be a better than an airtight seal made first, then an air purge of the fill hose, and after the fill a purge of hydrogen in the fill hose before you can disconnect.
Why hydrogen not used as a fuel?
ReplyDeleteIt is because hydrogen is a highly combustible and it reacts explosively when it comes in contact with air. And hence as a result, storing of the hydrogen gas is difficult and is dangerous at the same time. So, even though hydrogen has the highest calorific value, it is not used as a domestic fuel.
Microbial production of hydrogen:
Biophotolysis of water by microalgae and cyanobacteria
1,Hydrogenase-dependent hydrogen production-Gaffron and Rubin reported that a green alga, Scenedesmus, produced molecular hydrogen under light conditions after being kept under anaerobic and dark conditions.
Hydrogenase, the enzyme responsible for this hydrogen production, catalyses the following reaction:
(2H+ + 2Xreduced--)6 H2 + 2Xoxidized)
2,Nitrogenase-dependent hydrogen production-Benemann and Weare demonstrated that a nitrogen-fixing cyanobacterium, Anabaena cylindrica, produced hydrogen and oxygen gas simultaneously in an argon atmosphere for several hours. Nitrogenase is responsible for nitrogen-fixation and is distributed mainly among prokaryotes, including cyanobacteria, but does not occur in eukaryotes, under which microalgae are classified. Molecular nitrogen is reduced to ammonium with consumption of reducing power (e' mediated by ferredoxin) and ATP. The reaction is substantially irreversible and produces ammonia:
N2 + 6H1+ + 6e- --) 2HN3
12ATP 12(ADP+Pi)
However, nitrogenase catalyzes proton reduction in the absence of nitrogen gas (i.e. in an argon atmosphere).
2H+ + 2e---) H2
4ATP 4(ADP+Pi)
-Hydrogen production by photosynthetic bacteria
Photosynthetic bacteria undergo anoxygenic photosynthesis with organic compounds or reduced sulfur compounds as electron donors. Some non-sulfur photosynthetic bacteria are potent hydrogen producers, utilizing organic acids such as lactic, succinic and butyric acids, or alcohols as electron donors. Since light energy is not required for water oxidation, the efficiency of light energy conversion to hydrogen gas by photosynthetic bacteria, is in principle much higher than that by cyanobacteria. Hydrogen production by photosynthetic bacteria is mediated by nitrogenase activity, although hydrogenases may be active for both hydrogen production and hydrogen uptake under some conditions. Miyake and Kawamura demonstrated a maximum energy conversion efficiency (combustion energy of hydrogen gas produced/incident light energy) of 6 to 8% using Rhodobacter sp. in laboratory experiments
-Combined photosynthetic and anaerobic and bacterial hydrogen production
Anaerobic bacteria metabolize sugars to produce hydrogen gas and organic acids, but are incapable of further breaking down the organic acids formed. Miyake et al. proposed the combined use of photosynthetic and anaerobic bacteria for the conversion of organic acids to hydrogen. Theoretically, one mole of glucose can be converted to 12 moles of hydrogen through the use of photosynthetic bacteria capable of capturing light energy in such a combined system. From a practical point of view, organic wastes frequently contain sugar or sugar polymers. It is not however easy to obtain organic wastes containing organic acids as the main components. The combined use of photosynthetic and anaerobic bacteria should potentially increase the likelihood of their application in photobiological hydrogen production.
-18mbt014
Efficient cellulolytic fungi are represented by the species of Aspergillus, Penicillium,
ReplyDeleteChaetomium, Trichoderma,
Fusarium, Stachybotrys,
Cladosporium, Alternaria,
Acremonium, Ceratocystis,
Myrothecium, Humicola.
bacteria--- Bacteroides ,
Butyrivibrio fibrisolvens,
Ruminococcus albus,
Pseudomonas,
Streptomyces,
Rhodococcus,
Stentrophomonas,
Variovorax,
Serratia,
Clostridium.
18mbt014
Q MICROBIOLOGICAL WAYS OF PRODUCING HYDROGEN
ReplyDeleteA .Dark-fermentation- In fermentation-based systems, microorganisms, such as bacteria, break down organic matter to produce hydrogen. The organic matter can be refined sugars, raw biomass sources such as corn stover, and even wastewater. Because no light is required, these methods are sometimes called "dark fermentation" methods.
Microbial electrolysis cell (MEC)- represents an alternative electrically driven H2 production process, which facilitates the conversion of electron equivalents in organic compounds to H2 gas by combining microbial metabolism with bioelectrochemical reactions. Low-energy consumption compared to conventional water electrolysis, high product (H2) recovery, and substrate degradation than the dark fermentation process are some of the potential benefits that make MEC an alternate process.
Photofermentation- It is carried out by nonoxygenic photosynthetic bacteria that use sunlight and biomass to produce hydrogen. Purple non-sulfur (PNS) and green sulfur (GS) bacteria such as Rhodobacter spheroids and Chlorobium vibrioforme, respectively, are capable of producing hydrogen gas by using solar energy and reduced compounds.
indirect biophotolysis-
This process can be performed with certain cyanobacteria.
The hydrogen yields generated by either direct or indirect photolysis are unfortunately very low in comparison with other fermentative methods.
18MMB026
Q examples of lignocellulolytic Microbes.
ReplyDeleteA Bacteria: Clostridium, Cellulomonas, Bacillus, Pseudomonas, Fibribacter, Ruminococcus, Butyrivibrio
fungi: Aspergillus, Rhizopus, Trichoderma, Fusarium, Neurospora, Penicillium and actinomycetes (Thermomonospora, Thermoactinomyces)
18MMB026
This comment has been removed by the author.
ReplyDeleteWhy Hydrogen is not used as fuel ?
ReplyDelete1. Hydrogen burns with a clear flame and the friction of escaping through a tiny crack in the pipe or tubing containing it is sufficient to ignite it. so there is an invisible flame burning in the vehicle.
2. It takes a lot of energy to produce to break it down to hydrogen and oxygen. It can also be recovered from fractionating oil when producing fuels, but it is mixed with other gasses and has to be purified. Then it has to be compressed and cooled. It’s most useful form is liquid hydrogen, giving far more energy content than as a highly compressed gas.
3. Transporting it is a major safety issue
18MMB029
EXAMPLES OF CELLULOLYTIC MICROORGANISMS
ReplyDeleteBacteria :- Streptomyces,Stentrophomonas,Rhodococcus,Pseudomonas
Fungi :- Cladosporium, Alternaria,Aspergillus, Rhizopus.
18MMB029
Why hydrogen is not used as fuel?
ReplyDelete1) Hydrogen is difficult to store because the molecules are so small they can easily leak requiring specialised containers.
2) Hydrogen can also make metals brittle and prone to cracking.
3) nitrogen dioxide emission in a hydrogen fuel cell.
4) Highly flammable property of hydrogen when come in contact with air.
5) Hydrogen is a gaseous fuel. Gaseous fuel are less dense, they occupy more volume. So , hydrogen requires a large fuel tank for storage.
Microbial ways for hydrogen gas production.
ReplyDelete1) Water splitting photosynthesis/ biopholysis- The oxygenic photosynthetic microorganisms such as green microalgae and cyanobacteria use this process that requires only water and sunlight. A hydrogenase in green algae drives the evolution of hydrogen, whereas nitrogenase is responsible for this process in heterocystous cyanobacteria. The biopholysis is divided into direct and indirect process. In direct process the electrons are derived from light energy mediated water splitting are transferred through PS II and PS I to ferrodoxin as electron Carrier and the reduced FD reduces a hydrogenase enzyme that is responsible for hydrogen production.
2) Photofermentation - involves the conversation of light energy to biomass with the production of hydrogen and carbon dioxide. Particular purple nonsulfur PNS photosynthetic bacteria capture solar energy to transform organic acid into hydrogen using nitrogenase in the absence of ammonia ions.
3) Microbial electrolysis cells ( electrofermentation)- this technology resembles to an microbial fuel cell the primary difference is a small input of external voltage. A potential higher than 0.110V, in addition to that generated by microorganisms (-0.300 V ), will produce hydrogen gas. The normalvredox potential for the reduction of H+ to H2 is - 0.414 V ,therefore the potential requirement is very low compared with the theoretically required voltage of 1.230 V for the electrolysis of water. The MECs are capable of more than 90% efficiency in the production of hydrogen gas.
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ReplyDeleteQuestion) Microbiological ways of producing hydrogen
ReplyDeleteAns) Production of hydrogen by anaerobes, facultative anaerobes, aerobes, methylotrophs, and photosynthetic bacteria is possible.
Method for hydrogen production by microbes:
1) Photofermentation
•Photofermentative hydrogen production is a bioprocess in which photosynthetic purple nonsulfur bacteria grow heterotrophically on organic acids like acetic acid, lactic acid and butyric acid and produce hydrogen using light energy under anaerobic conditions.
•Two enzymes are specifically involved in hydrogen production, namely nitrogenase and hydrogenase.
•Nitrogenases produce hydrogen under nitrogen-limited conditions acting as ATP-dependent hydrogenase, hydrogenases have the ability for both production and consumption of molecular hydrogen depending on the type of hydrogenase and physiological conditions.
•Photofermentation process can be achieved in a wide variety of conditions such as in batch or continuous mode, upon artificial or solar illumination, utilizing various carbon and nitrogen sources including food industry wastewater and dark fermentation effluents.
2) Direct biophotolysis
•This method is similar to the processes found in plants and algal photosynthesis. In this process solar energy is directly converted to hydrogen via photosynthetic reactions.
•Algae split water molecules to hydrogen ion and oxygen via photosynthesis. The generated hydrogen ions are converted into hydrogen gas by hydrogenase enzyme.
•Chlamydomonas reinhardtii is one of the well-known hydrogen producing algae.
•The advantage of this method is that the primary feed is water, which is inexpensive and available almost everywhere.
3) Dark fermentation
•Hydrogen can be produced by anaerobic bacteria, grown in the dark on carbohydrate-rich substrates. Bacteria known to produce hydrogen include species of Enterobacter, Bacillus, and Clostridium.
•Carbohydrates, mainly glucose, are the preferred carbon sources for fermentation processes, which predominantly give rise to acetic and butyric acids together with
hydrogen gas.
•Currently fermentative processes produce 2.4 to 3.2 moles of hydrogen per mole glucose.
4) Hybrid systems
1) one step hybrid system
2) two step hybrid system
•This process uses useless and difficult to operate substrates in the photofermentation process. The advantage of one step hybrid systems is the high rate and much higher yield in hydrogen production than dark fermentation.
•The natural organic substrates and wastes that can be used in two step hybrid system. One mole of glucose theoretically generates 4 moles of hydrogen in dark fermentation, whereas acetic acid is the only side product. In practice, dark fermentation of liquid wastes generates much lower amounts of hydrogen. The hybrid systems are much more efficient.
5) Microbial electrolysis cell
•Microbial electrolysis cell (MEC) can achieve sustainable and clean hydrogen production from a wide range of renewable biomass and wastewaters.
•Enhancing the hydrogen production rate and lowering the energy input are the main challenges of MEC technology.
•One of the main features of MECs is that they allow organic matter present in wastewater to be converted into hydrogen thus helping to offset the energy consumed during treatment.
•In microbial electrolysis cells, microbes (tan ovals) consume organic matter such as acetic acid, producing electrons (e-) and protons (hydrogen ions, H+). The electrons are passed to an electrode and travel through a wire to the electrode in the cathode section of the MEC. Here, with the help a small added voltage, the protons are combined with the electrons to produce hydrogen gas.
6) Indirect Biophotolysis
•Cyanobacteria possess key enzymes (nitrogenase and hydrogenase) that carry out metabolic functions in order to achieve hydrogen generation. Because of the higher rates of H2
production by Anabaena species and strains.
Q What is Rheology?
ReplyDeleteRheology is a branch of physics that deals with the study of flow of liquid matter and deformation of solid materials.
Newtonian fluid It is characterized by a single coefficient of viscosity for a specific temperature and it does not change with the strain rate.
Non-Newtonian fluid
It includes large class of fluid whose viscosity changes with the strain rate.
Rheology generally accounts for behavior of Non-Newtonian fluids.
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Q:- why hydrogen gas cannot be used as fuel despite being the purest and pollution free? Ans:- Hydrogen is high in energy yet an engine that burns pure hydrogen produces almost no pollution.NASA has used liquid hydrogen since the 1970s to propel the space shuttle and other rockets into orbit..But fuels like natural gas, methanol,or even gasoline can be reformed to produce the hydrogen required for fuel cells. Although hydrogen has the highest calorific value it is not used as a domestic fuel.it is because hydrogen is highly combustible and it reacts explosively when it comes in contact with air.. Need to transport it from the manufacturing plant to the refueling stations.that means heavy trucks because a pipeline is unworkable .That is a major safety issue.propane and LNG have similar safety issues but are safer to transport than hydrogen. 18mmb011
ReplyDeleteQ:- list of cellulolytic microorganisms And:- Fungal cellulose:- Trichoderma, Aspergillus,Phanerochaete,Fomitopsis. Bacteria belonging to the general Clostridium,Cellulomonas,Cellulosimicrobium,Thermomonospora,Streptomycin,Microbispora.have been observed to produce different kinds of cellulase when incubated under anaerobic or aerobic conditions. 18mmb011.
ReplyDeleteQ: List of cellulolytic microorganisms
ReplyDeleteAns:
Bacterial species: Trichonympha, Clostridium, Actinomycetes,Bacteroides succinogens,Butyrivibrio fibrisolvens, Ruminococcus Albus,Methanobrevibacter ruminantium.
Fungal species: Fusarium,Chaetomium,Myrothecium, Trichoderma, Penicillin, Aspergillus. 18mmb022
The yeast Saccharomyces cerevisiae consumes mono- and disaccharides preferentially to any other carbon source. Since sugars do not freely permeate biological membranes, cellular uptake of these compounds requires the action of ‘transporters’.Yeast cells show two transporters for monosaccharides, the so-called glucose and galactose transporters that act by a facilitated diffusion mechanism. In the case of glucose transport, which also acts upon d-fructose and d-mannose, two components with high- and low-affinity constants have been identified kinetically. Activity of the high-affinity component is dependent on the presence of active kinases whereas activity of the low-affinity component is independent of the presence of these enzymes. Three genes, SNF3, HXT1 and HXT2, encode three different glucose transporters with a high affinity for the substrates and are repressed by high concentrations of glucose in the medium.
ReplyDeleteSaccharomyces cerevisiae uses two glucose transporter homologs, Snf3 and Rgt2, as glucose sensors that generate a signal for induction of expression of genes encoding hexose transporters (HXT genes).
Hence,yeast senses glucose using two modified glucose transporters that serve as glucose receptors.
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Q) Why Saccharomyces cerevisiae possess 32 glucose transporters?
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QUE = Microbial way of producing hydrogen
ReplyDeleteHydrogenases are the extremely active enzymes responsible for the vast majority of microbial H2production. They are thought to be among the most ancient of enzymes, tracing back over 3.6 billion years to when the Earth’s atmosphere was thick with H2 and completely devoid of oxygen. The two main classes of hydrogenase are known as [FeFe] and [NiFe] according to the metals contained at their catalytic centres. They perform a remarkable chemical reaction by combining protons (H+) with electrons (basically electricity) to generate H2, and they are said to perform this reaction even more efficiently than the best platinum catalysts currently available. It is possible to isolate hydrogenase enzymes, hook them up to a source of electrons (an electrode), and then drive H2 production in the test tube. It is also possible to couple these enzymes with different ones (such as laccases, which are copper-dependent oxidases, or carbon monoxide dehydrogenases) to generate bio-batteries or other H2-producing devices. Attempts have even been made to connect hydrogenases directly to photosynthetic complexes in an effort to generate biohydrogen directly from sunlight. Unfortunately, the problems with hydrogenases are that they are fragile and often inactivated by oxygen, an element that pervades our atmosphere.
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Glucose transport in Saccharomyces cerevisiae.
ReplyDeleteIn Saccharomyces cerevisiae glucose transport takes place through facilitated diffusion.The transport proteins are mainly from the Hxt family, but many other transporters have been identified.
name of transporters and function
Snf3- low-glucose sensor; repressed by glucose; low expression
level; repressor of Hxt6
Rgt2- high-glucose sensor; low expression level
Hxt1- Km: 100 mM, 129 - 107 mM, low-affinity glucose transporter; induced by high glucose level
Hxt2- Km = 1.5 - 10 mM high/intermediate-affinityglucose transporter; induced by low glucose level
Hxt3- Vm = 18.5, Kd = 0.078, Km = 28.6/34.2- 60 mMlow-affinity glucose transporter
Hxt4- Vm = 12.0, Kd = 0.049, Km = 6.2 intermediate-affinity glucose transporter
Hxt5- Km = 10 mM Moderate glucose affinity. Abundant during stationary phase, sporulation and low glucose conditions. Transcription repressed by glucose.
Hxt6- Vm = 11.4, Kd = 0.029, Km = 0.9/14,1.5 mM high glucose affinity
Hxt7- Vm = 11.7, Kd = 0.039, Km = 1.3, 1.9, 1.5 mM high glucose affinity
Hxt8- low expression level
Hxt9- involved in pleiotropic drug resistance
Hxt11- involved in pleiotropic drug resistance
Gal2- Vm = 17.5, Kd = 0.043, Km = 1.5, 1.6 high galactose affinity
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ReplyDeleteEXAMPLES OF CELLULOLYTIC MICROORGANISMS:
ReplyDeleteFungi-Chaetomium, Fusarium Myrothecium, Trichoderma, Penicillium, Aspergillus, and so forth, are some of the reported fungal species
Bacteria-Cellulolytic bacterial species include Trichonympha, Clostridium, Bacteroides succinogenes, Butyrivibrio fibrisolvens, Ruminococcus albus, and Methanobrevibacter ruminantium
MICROBIOLOGICAL WAYS OF PRODUCING HYDROGEN:
ReplyDeleteProduction of hydrogen by anaerobes facultativeanaerobes,aerobes,methylotrophs, and photosynthetic bacteria is possible.Anaerobic Clostridia are potential producers and immobilized C. butyricum produces 2 mol H2/mol glucose at 50% efficiency. Spontaneous production of H2 from formate and glucose by immobilized Escherichia coli showed 100% and 60% efficiencies, respectively. Enterobactericiae produces H2 at similar efficiency from different mono-saccharides during growth. Among methylotrophs, methanogenes, rumen bacteria, and thermophilic archae, Ruminococcus albus, is promising (2.37 mol/mol glucose). Immobilized aerobic Bacillus licheniformis optimally produces 0.7 mol H2/mol glucose. Photosynthetic Rhodospirillum rubrum produces 4, 7, and 6 mol of H2 from acetate, succinate, and malate, respectively. Excellent productivity (6.2 mol H2/mol glucose) by co-cultures of Cellulomonas with a hydrogenase uptake (Hup) mutant of R. capsulata on cellulose was found. Cyanobacteria, viz., Anabaena, Synechococcus, and Oscillatoria sp., have been studied for photoproduction of H2. Immobilized A. cylindrica produces H2 (20 ml/g dry wt/h) continually for 1 year. Increased H2 productivity was found for Hup-mutant of A. variabilis. Synechococcus sp. has a high potential for H2 production in fermentors and outdoor cultures. Simultaneous productions of oxychemicals and H2 by Klebseilla sp. and by enzymatic methods were also attempted. The fate of H2 biotechnology is presumed to be dictated by the stock of fossil fuel and state of pollution in future.
- Direct biophotolysis
This method is similar to the processes found in plants and algal photosynthesis. In this process solar energy is directly converted to hydrogen via photosynthetic reaction
2H2O + ‘light energy’→ 2H2 + O2.
Algae split water molecules to hydrogen ion and oxygen via photosynthesis.The generated hydrogen ions are converted into hydrogen gas by hydrogenase enzyme. Chlamydomonas reinhardtii is one of the well-known hydrogen producing algae .Hydrogenase activity has alsobeen observed in other green algae like Scenedesmus obliquus, Chlorococcum littorale,Platymonas subcordiformis and Chlorella fusca.Theadvantage of this method is that the primary feed is water, which is inexpensive and available almost everywhere
A direct biophotolysis method must perforce operate at a partial pressure of near one atmosphere of O2, which is a thousand-fold greater than the maximum likely to be tolerated. Thus, the O2 sensitivity of the hydrogenase enzyme reaction and supporting reductant generating pathway remains the key problem.
Indirect Biophotolysis
In indirect biophotolysis, problems of sensitivity of the hydrogen evolvingprocess are potentially circumvented by separating temporally and/or spatially oxygen evolution and hydrogen evolution. Thus indirect biophotolysis processes involve separation of the H2 and O2 evolution
reactions into separate stages, coupled through CO2 fixation/evolution. Cyanobacteria have the unique characteristics of using CO2 in the air as a carbon source and solar energy as an energy source. The cells take up CO2 first to produce cellular substances, which are
subsequently used for hydrogen production . The overall mechanism of hydrogen
production in cyanobacteria can be represented by the following reactions:
12H2O + 6CO2 + ‘light energy’→ C6H12O6 + 6O2
C6H12O6 + 12H2O + ‘light energy’→ 12H2 + 6CO2
Cyanobacteria possess key enzymes (nitrogenase and hydrogenase) that carry out metabolic functions in order to achieve hydrogen generation . Because of the higher rates of H2 production by Anabaena species and strains, these have been subject to intense study. In indirect biophotolysis mutant strains of A. Variabilis have demonstrated hydrogen production rate
of the order of 0.355 mmol/h per liter.
Dark fermentation
Hydrogen can be produced by anaerobic bacteria, grown in the dark on carbohydrate-rich substrates. Bacteria known to produce hydrogen include species of Enterobacter, Bacillus, and Clostridium.
Roles of Multiple glucose transporters in Saccharomyces cerevisiae:
ReplyDeleteIn Saccharomyces cerevisiae, TRK1 and TRK2 are required for high- and low-affinity K+ transport. Among suppressors of the K+ transport defect in trk1 delta trk2 delta cells, we have identified members of the sugar transporter gene superfamily. One suppressor encodes the previously identified glucose transporter HXT1, and another encodes a new member of thisfamily, HXT3. The inferred amino acid sequence of HXT3 is 87% identical to that of HXT1, 64% identical to that of HXT2, and 32%identical to that of SNF3. Like HXT1 and HXT2, over expression of HXT3 in snf3 delta cells confers growth on low-glucose or raffinose media. The function of another new member of the HXT superfamily, HXT4 (previously identified by its ability to suppress the snf3 delta phenotype, was revealed that deleted all possible combinations of the five members of the glucose transporter gene family. Neither SNF3, HXT1, HXT2, HXT3, nor HXT4 is essential for viability. snf3 delta hxt1 delta hxt2 delta hxt3 delta hxt4 delta cells are unable to grow on media containing high concentrations of glucose (5%) but can grow on low-glucose (0.5%) media, revealing the presence of a sixth transporter that is itself glucose repressible. This transporter may be negatively regulated by SNF3 since expression of SNF3 abolishes growth of hxt1 delta hxt2 delta hxt3 delta hxt4 delta cells on low-glucose medium. HXT1, HXT2, HXT3, and HXT4 can function independently: expression of any one of these genes is sufficient to confer growth on medium containing at least 1% glucose. A synergistic relationship between SNF3 and each of the HXT genes is suggested by the observation that SNF2 hxt1 delta hxt2 delta hxt3 delta hxt4 delta cells and snf3 delta HXT1 HXT2 HXT3 HXT4 cells are unable to grow on raffinose (low fructose) yet SNF3 in combination with any single HXT gene is sufficient for growth on raffinose.The most important glucose transporters in Saccharomyces cerevisiae, are facilitated diffusion transporters. Apparent Km‐values from high to low affinity, determined from countertransport and initial‐uptake experiments, respectively, are: Hxt6 0.9±0.2 and 1.4±0.1 mM, Hxt7 1.3±0.3 and 1.9±0.1 mM, Gal2 1.5 and 1.6±0.1 mM, Hxt2 2.9±0.3 and 4.6±0.3 mM, Hxt4 6.2±0.5 and 6.2±0.3 mM, Hxt3 28.6±6.8 and 34.2±3.2 mM, and Hxt1 107±49 and 129±9 mM. From both independent methods, countertransport and initial uptake, the same range of apparent Km‐values was obtained for eachtransporter. In contrast to that in human erythrocytes, the facilitated diffusion transport mechanism of glucose in yeast was symmetric.
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ReplyDelete18MMB007
ReplyDeleteQuestion: what is immobilization?
Answer: Immobilization
Immobilization is the conversion of an element from an inorganic to organic form by microorganisms. If a particular nutrient is limiting to microbial metabolism, nutrients liberated by mineralization or nutrients available from other soil pools will be taken up and retained by the microbial biomass rendering these nutrients unavailable for plant uptake. Thus, under conditions of nutrient limitation, the microorganisms compete with plants for nutrient made available from mineralization, chemical weathering, and atmospheric deposition. Rates of immobilization are a function of labile organic matter concentrations, litter quality (especially nutrient concentrations), and availability of nutrients from other soil pools. The amount of nutrient made available for plant uptake is termed net mineralization which is equal to gross mineralization minus immobilization.
Q Methods of immobilization?
ReplyDeleteA Adsorption
Covalent bonding
Cross linking
entrapment
copolymerization
encapsulation
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Q Why hydrogen cannot be used as fuel?
ReplyDeleteA (1) It is because hydrogen is highly combustible and it reacts explosively when it comes in contact with air.
(2) The amount of cost required to generate hydrogen is higher.
(3) Hydrogen burning vehicles are inefficient as they rely on combustion engines, so higher cost of money is required to operate such vehicles.
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Q Methods of immobilization?
ReplyDelete1 Adsorption
2 Cross- linking
3 Covalent bonding
4 Chelation
5 Affinity binding
6 Encapsulation
7 Entrapment
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Q-why various transporter require to transport glucose in Saccharomyces cerevisiae?
ReplyDeleteANS:The yeast Saccharomyces cerevisiae consumes mono- and disaccharides preferentially to any other carbon source. Since sugars do not freely permeate biological membranes, cellular uptake of these compounds requires the action of 'transporters'. The purpose of this review is to summarize the present knowledge on sugar transport in this organism. Yeast cells show two transporters for monosaccharides, the so-called glucose and galactose transporters that act by a facilitated diffusion mechanism. In the case of glucose transport, which also acts upon D-fructose and D-mannose, two components with high- and low-affinity constants have been identified kinetically.Three genes, SNF3, HXT1 and HTE2, encode three different glucose transporters with a high affinity for the substrates and are repressed by high concentrations of glucose in the medium. Kinetic studies suggest that at least one additional gene exists that encodes a transporter with a low affinity and is expressed constitutively. Galactose transport has only one natural substrate, D-galactose, and is encoded by the gene GAL2. Expression of this gene is induced by galactose and repressed by glucose. Two transporters for disaccharides have been identified in S. cerevisiae: maltose and alpha-methylglucoside transporters. These transporters are H(+)-symports that depend on the electrochemical proton gradient and are independent of the ATP level. The gene that encodes the maltose transporter is clustered with the other two genes required for maltose utilization in a locus that is found repeated at different chromosomal locations. Its expression is induced by maltose and repressed by glucose. The rate of sugar uptake in yeast cells is controlled by changes in affinity of the corresponding transporters as well as by an irreversible inactivation that affects their V max.
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Q-what is immobilization? and what are the method of immobilization?
ReplyDeleteANS: Immobilization of enzymes (or cells) refers to the technique of confining/anchoring the enzymes (or cells) in or on an inert support for their stability and functional reuse. By employing this technique, enzymes are made more efficient and cost-effective for their industrial use.
There are four principal methods available for immobilising enzymes:
A adsorption
B covalent binding
C entrapment
D membrane confinement
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Q- way to produce hydrogen
ReplyDeleteANS:In fermentation-based systems, microorganisms, such as bacteria, break down organic matter to produce hydrogen. The organic matter can be refined sugars, raw biomass sources such as corn stover, and even wastewater. Because no light is required, these methods are sometimes called "dark fermentation" methods.
In direct hydrogen fermentation, the microbes produce the hydrogen themselves. These microbes can break down complex molecules through many different pathways, and the byproducts of some of the pathways can be combined by enzymes to produce hydrogen. Researchers are studying how to make fermentation systems produce hydrogen faster (improving the rate) and produce more hydrogen from the same amount of organic matter (increasing the yield).
Microbial electrolysis cells (MECs) are devices that harness the energy and protons produced by microbes breaking down organic matter, combined with an additional small electric current, to produce hydrogen. This technology is very new, and researchers are working on improving many aspects of the system, from finding lower-cost materials to identifying the most effective type of microbes to use.
Production of hydrogen by anaerobes, facultative anaerobes, aerobes, methylotrophs, and photosynthetic bacteria is possible. Anaerobic Clostridia are potential producers and immobilized C. butyricum produces 2 mol H2/mol glucose at 50% efficiency. Spontaneous production of H2 from formate and glucose by immobilized Escherichia coli showed 100% and 60% efficiencies, respectively. Enterobactericiae produces H2 at similar efficiency from different monosaccharides during growth.
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Q- why hydrogen can not use as fuel?
ReplyDeleteANS: Because -Nitrogen Dioxide Emission in a hydrogen fuel cell
- Storage Issues and difficults in Transportation
- High Cost- the process is very expensive
-Highly Flammable property of hydrogen is a risk
factor.
The energy can be delivered to fuel cells and generate electricity and heat, or burned to run a combustion engine. In each case hydrogen is combined with oxygen to form water. The heat in a hydrogen flame is a radiant emission from the newly formed water molecules.
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Que: which are the most famous cellulolytic micro organisms?
ReplyDeleteAns : Trichoderma
Humicola
Penicillium
Aspergillus
Etc fungal species.
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Methods of immobilization.
ReplyDeletePhysical method:
(1) Adsorption
(2) Physical deposition
(3) Entrapment
(4) Membrane system
(5) Two phase system
Chemical methods:
(1) Covalent binding
(2) Cross linking
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Cellulolytic microorganisms.
ReplyDeleteFungi:(1)Trichoderma sp.
(2)Aspergillus niger
(3)Aspergillus fumigatus
(4)Aspergillus flavus
-It was found that among them Trichoderma gave higher cellulolytic activity than other three fungi.
(5)Piptoporus betulinus
(6)Humicola
(7)Penicillium
Bacteria:(1)Trichonympha
(2)Clostridium
(3)Actinomycetes
(4)Ruminococcus albus
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Celluloytic microorganism:
ReplyDeleteBacteria belonging to the genera Clostridium, Cellulomonas, Cellulosimicrobium, Thermomonospora, Bacillus, Ruminococcus, Erwinia, Bacteriodes, Acetovibrio, Streptomyces, Microbispora, Fibrobacter, and Paenibacillus have been observed to produce different kinds of cellulase when incubated under aerobic or anaerobic condition.
Fungi:
Cellulolytic fungi, especially the soft-rot fungi, such as members of the genera Trichoderma, Humicola and Penicillium, and the white-rot fungi, such as members of the genera Phanerochaete and Pycnoporus, are among the most studied fungi.
Trichoderma reesei (teleomorph: Hypocrea jecorina) is one of the best characterized fungi and the most efficient producers of cellulases and hemicellulases.
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Cellulolytic microorganisms:There is a wide spectrum of microorganisms which can produce the variety of enzymes like cellulase under appropriate conditions. ... Many fungi capable of degrading cellulose synthesize large quantities of extracellular cellulases that are more efficient in depolymerising the cellulose substrate
ReplyDeleteFungal species:Aspergillus, Rhizopus, Trichoderma, Fusarium, Neurospora, Penicillium.
actinomycetes spp : Thermomonospora ,Thermoactinomyces
Bacterial species:Clostridium, Cellulomonas, Bacillus, Pseudomonas, Fibribacter, Ruminococcus, Butyrivibrio, etc.
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Que: Why hydrogen cannot be used as fuel?
ReplyDeleteAns: (1) It is because hydrogen is highly combustible and it reacts explosively when it comes in contact with air.
(2) The amount of cost required to generate hydrogen is higher.
(3) Hydrogen burning vehicles are inefficient as they rely on combustion engines, so higher cost of money is required to operate such vehicles.
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ReplyDeleteQue: Examples of cellulolytic bacteria.
ReplyDeleteans:Trichonympha, Clostridium, Actinomycetes, Bacteroides succinogenes, Butyrivibrio fibrisolvens, Ruminococcus albus, Methanobrevibacter ruminantium.
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Que: Why hydrogen could not be use as a fuel?
ReplyDeleteAns:There are 3 major problems with hydrogen as a vehicle fuel, compared to gasoline.
1 - It takes a lot of energy to produce. You have to run a lot of electricity through water to break it down to hydrogen and oxygen. It can also be recovered from fractionating oil when producing fuels, but it is mixed with other gasses and has to be purified. Then it has to be compressed and cooled. It’s most useful form is liquid hydrogen, giving far more energy content than as a highly compressed gas. The container has to be thick walled and insulated, therefore heavy, and a means has to be made to safely alleviate excess pressure due to boil-off.
2 - You need to transport it from the manufacturing plant to the refueling stations. That means heavy trucks, because a pipeline is unworkable. That is a major safety issue. Propane and LNG have similar safety issues, but are safer to transport than hydrogen.
3 - Hydrogen burns without any color to indicate a fire. This becomes a problem refueling your vehicle.
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Que:Which tyep of methods are used in the recovery of citric acid?
ReplyDeleteAns.recovery of citric acid generally performed by three methods
1) precipitation
2) extraction
3) adsorption (ionexachnger resin)
The recovery of citric acid from fermented broth is
generally performed through three procedures: precipi-
tation, extraction and adsorption (mainly using ion ex-
change resins). The first method is the most frequently
used and it is applicable in all types of processes. The
second one requires a fermented broth with little impu-
rities. In both of the methods there is the need to re-
move the fermented broth, micelles of the fungus, and
materials in suspension by filtration
Precipitation method is the classical method and it is
performed by the addition of calcium oxide hydrate
(milk of lime). The acid is transformed into tri-calcium ci-
trate tetrahydrate, which is lightly soluble. The precipi-
tate is recovered by filtration, treated with sulphuric acid
forming calcium sulphate (gypsum), which is filtered off.
Mother liquor of citric acid solution is treated with active
carbon and passed through cation and anion exchangers.
Finally, the liquor is concentrated in vacuum crystallizers
at 20–25 °C, forming citric acid monohydrate
Anhydrous citric acid is obtained at crystallization tem-
perature higher than 36.5 °C. The crystals are separated
by centrifugation and the dry stage is conducted at a
temperature bellow 36.5 °C for monohydrate product
and above this for anhydrous product Generally, a
bed flowing dryer is used. Two kinds of wastes are gen-
erated through precipitation technique: the microorgan-
ism residue contains proteins, amino acids, inorganic
matter, sugar, colloid, pigment, biotin, etc., and the other
is calcium sulphate. The first one can be dried and used
as forage or supplied to forage factory and the second
can be supplied to cement factories .
The solvent extraction is another alternative to puri-
fication and crystallization of citric acid. The mother li-
quor contains small amount of impurities captured by
the solvents. This method has the advantage of avoiding
the use of calcium hydroxide and sulphuric acid, which
are employed in great amounts, and the production of
gypsum. In this case a mixture of n-octyl alcohol, trido-
decylamine and isoalkane is used. Other solvents such
as acetone, methanol and ethanol were tested in order to
extract citric acid from solid particles in solid-state pro-
cesses. Better results using extraction technique at nor-
mal temperature (20–25 °C) were achieved with acetone,
followed by water, ethanol and methanol. Liquid-liquid
extraction of citric acid has been found to be a promis-
ing alternative to the conventional process. Suitable ex-
tractants as phosphorous-based oxygen-containing and
amine-based extractants, with functional groups effec-
tive for reversible complexation with acids, should be used
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Question) What is cellulolytic microorganisms? Give example of cellulolytic organisms.
ReplyDeleteAns) Cellulolytic microorganisms play an important role in the biosphere by recycling cellulose, the most abundant carbohydrate produced by plants. All organisms known to degrade cellulose efficiently produce a battery of enzymes with different specificities, which act together in synergism.
•Many microorganisms have been reported with cellulosic activities including many bacterial and fungal strains both aerobic and anaerobic. Chaetomium, Fusarium Myrothecium, Trichoderma. Penicillium, Aspergillus, and so forth, are some of the reported fungal species responsible for cellulosic biomass hydrolysation. Cellulolytic bacterial species include Trichonympha, Clostridium, Actinomycetes, Bacteroides succinogenes, Butyrivibrio fibrisolvens, Ruminococcus albus, and Methanobrevibacter ruminantium.
•Cellulolytic fungi: Fungi capable of utilizing (breaking down) cellulose-containing material. Examplesinclude Chaetomium species and Stachybotrys species.
•Cellulolytic fungi, especially the soft-rot fungi, such as members of the genera Trichoderma, Humicola and Penicillium, and the white-rot fungi, such as members of the genera Phanerochaeteand Pycnoporus.
QUE - Example of cellulolytic microorganisms
ReplyDeleteANS- Chaetomium, Fusarium Myrothecium, Trichoderma. Penicillium, Aspergillus, and so forth, are some of the reported fungal species responsible for cellulosic biomass hydrolysation.
Cellulolytic bacterial species include Trichonympha, Clostridium, Actinomycetes, Bacteroides succinogenes, Butyrivibrio fibrisolvens, Ruminococcus albus, and Methanobrevibacter ruminantium.
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QUE - Methods for immobilization
ReplyDeleteANS-
1) adsorption
2) covalent binding
3) entrapment
4) membrane confinement
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Q. What is immobilization and the methods used?
ReplyDeleteAns:Immobilization is defined as the imprisonment of cell or enzyme in a distinct support or matrix. The support or matrix on which the enzymes are immobilized allows the exchange of medium containing substrate or effector or inhibitor molecules. The practice of immobilization of cells is very old and the first immobilized enzyme was amino acylase of Aspergillus oryzae for the production of L-amino acids
Methods of Immobilization: Based on support or matrix and the type of bonds involved, there are five different methods of immobilization of enzyme or whole cells.
(1) Adsorption
(2) Covalent bonding
(3) Entrapment
(4) Copolymerization
(5) Encapsulation
Advantages of whole cell immobilization:
(a) Multiple enzymes can be introduced to a single step
(b) Extraction and purification of enzymes are not required
(c) Enzymes are stable for long time
(d) Native conformation of enzyme is best maintained
(e) Cell organelles like mitochondria and chloroplasts can be immobilized
(f) Cost effective method.
18MBT031
ReplyDeleteQ. Cellulolytic microorganisms
Ans: Cellulolytic microorganisms play an important role in the biosphere by recycling cellulose, the most abundant carbohydrate produced by plants.
Cellulose is a simple polymer, but it forms insoluble, crystalline microfibrils, which are highly resistant to enzymatic hydrolysis.
All organisms known to degrade cellulose efficiently produce a battery of enzymes with different specificities, which act together in synergism. The study of cellulolytic enzymes at the molecular level has revealed some of the features that contribute to their activity.
In most cellulolytic organisms, cellulase synthesis is repressed in the presence of easily metabolized, soluble carbon sources and induced in the presence of cellulose. Induction of cellulases appears to be effected by soluble products generated from cellulose by cellulolytic enzymes synthesized constitutively at a low level. These products are presumably converted into true inducers by transglycosylation reactions.
Several applications of cellulases or hemicellulases are being developed for textile, food, and paper pulp processing. These applications are based on the modification of cellulose and hemicellulose by partial hydrolysis.
Total hydrolysis of cellulose into glucose, which could be fermented into ethanol, isopropanol or butanol, is not yet economically feasible.
Examples: Cellulolytic groups could be assigned to the family of Bacillaceae and to the genera Cellulomonas, Microbacterium and Lactobacillus.
ReplyDeleteQ. Cellulolytic microorganisms
Ans: Cellulolytic microorganisms play an important role in the biosphere by recycling cellulose, the most abundant carbohydrate produced by plants.
Cellulose is a simple polymer, but it forms insoluble, crystalline microfibrils, which are highly resistant to enzymatic hydrolysis.
All organisms known to degrade cellulose efficiently produce a battery of enzymes with different specificities, which act together in synergism. The study of cellulolytic enzymes at the molecular level has revealed some of the features that contribute to their activity.
In most cellulolytic organisms, cellulase synthesis is repressed in the presence of easily metabolized, soluble carbon sources and induced in the presence of cellulose. Induction of cellulases appears to be effected by soluble products generated from cellulose by cellulolytic enzymes synthesized constitutively at a low level. These products are presumably converted into true inducers by transglycosylation reactions.
Several applications of cellulases or hemicellulases are being developed for textile, food, and paper pulp processing. These applications are based on the modification of cellulose and hemicellulose by partial hydrolysis.
Total hydrolysis of cellulose into glucose, which could be fermented into ethanol, isopropanol or butanol, is not yet economically feasible.
Examples: Cellulolytic groups could be assigned to the family of Bacillaceae and to the genera Cellulomonas, Microbacterium and Lactobacillus.
18MBT031
Question : Microbiological ways of producing hydrogen..!
ReplyDeleteAnswer:
Fermentation-based systems:
Microorganisms, such as bacteria, break down organic matter to produce hydrogen. The organic matter can be refined sugars, raw biomass sources such as corn stover, and even wastewater. Because no light is required, these methods are sometimes called "dark fermentation" methods.
Direct hydrogen fermentation:
The microbes produce the hydrogen themselves. These microbes can break down complex molecules through many different pathways, and the byproducts of some of the pathways can be combined by enzymes to produce hydrogen. Researchers are studying how to make fermentation systems produce hydrogen faster and produce more hydrogen from the same amount of organic matter .
Microbial electrolysis cells (MECs):
That are devices that harness the energy and protons produced by microbes breaking down organic matter, combined with an additional small electric current, to produce hydrogen. This technology is very new, and researchers are working on improving many aspects of the system, from finding lower-cost materials to identifying the most effective type of microbes to use.
18MMB015
Question : Why hydrogen cannot be used as a fuel?
ReplyDeleteAns. Hydrogen makes excellent fuel for rockets because of its flammability. While hydrogen is flammable, it is not very much more flammable than gasoline.
Nitrogen Dioxide Emission
Critics of hydrogen fuel cells argue that although these cells do not emit carbon after burning, they give out nitrogen dioxide and other emissions. Nitrogen dioxide is a toxic gas and can still be harmful when ingested by humans. Experts say talk about the risks of respiratory problems such as lung edema from exposure with lethal dose even for a short period of time. Moreover, it can also decrease lung function.
Storage Issues
Apart from taking much time to separate the compounds of hydrogen, this element is also a challenge to move and transport. Compared to oil which can be channeled through pipelines and coal which can be moved to one location to another using trucks, transporting hydrogen can be expensive. This is one obvious setback of this element since storage and transport can be considered impractical.
High Cost
Aside from having to spend a lot of money to transport hydrogen, the time it takes to break down its elements makes the process expensive as well. This is also one of the reasons why hybrid cars are also costly. As long as no other options are applied to make the process faster and easier, hydrogen as fuel cells will remain to be pricey. Additionally, most cars being manufactured are still powered with conventional energy source like gas and diesel. Converting these already manufactured cars into hydrogen-powered vehicles will require a lot of work and money.
Highly Flammable
Skeptics have expressed concerns on the safety of using hydrogen fuel cells in cars and other applications because of the fear of explosion especially in higher concentrations. Although scientists have tested it several times, they do not rule out that this element is flammable. In case of fire, hydrogen flame is not seen in daylight, making it dangerous for fire fighters who will respond to the incident. This concern is also placed on liquid hydrogen. Being colorless and odorless, inhalation and ingestion is possible without being noticed and if this happens, asphyxiation can happen to people who are in an area without proper or no ventilation.
18MMB015
Q. Why hydrogen cannot be used as fuel? Ans:
ReplyDeleteAlthough hydrogen has the highest calorific value, it is not used as a domestic fuel.
It is because hydrogen is a highly combustible and it reacts explosively when it comes in contact with air.
And hence as a result, storing of the hydrogen gas is difficult and is dangerous at the same time. So, even though hydrogen has the highest calorific value, it is not used as a domestic fuel.
18MBT031
Q. What is immobilization? What are the methods used for microbial cell immobilization..!
ReplyDeleteAns. The technique used for the physical or chemical fixation of cells, organelles, enzymes, or other proteins (e.g. monoclonal antibodies ) onto a solid support, into a solid matrix or retained by a membrane, in order to increase their stability and make possible their repeated or continued use is called immobilization..
Gel entrapment, Encapsulation ,Adsorption/Adhesion etc methods for to prepare immobilized cells.
18MMB015
Question : Hydrogen gas produced by Microbes...!
ReplyDeleteAnswer :
Hydrogen gas is seen as a future energy carrier by virtue of the fact that it is renewable, does not evolve the "greenhouse gas" CO2 in combustion, liberates large amounts of energy per unit weight in combustion, and is easily converted to electricity by fuel cells. Biological hydrogen production has several advantages over hydrogen production by photoelectrochemical or thermochemical processes. Biological hydrogen production by photosynthetic microorganisms for example, requires the use of a simple solar reactor such as a transparent closed box, with low energy requirements. Electrochemical hydrogen production via solar battery-based water splitting on the hand, requires the use of solar batteries with high energy requirements.
Hydrogen production by photosynthetic bacteria
Photosynthetic bacteria undergo anoxygenic photosynthesis with organic compounds or reduced sulfur compounds as electron donors. Some non-sulfur photosynthetic bacteria are potent hydrogen producers, utilizing organic acids such as lactic, succinic and butyric acids, or alcohols as electron donors. Since light energy is not required for water oxidation, the efficiency of light energy conversion to hydrogen gas by photosynthetic bacteria, is in principle much higher than that by cyanobacteria. Hydrogen production by photosynthetic bacteria is mediated by nitrogenase activity, although hydrogenases may be active for both hydrogen production and hydrogen uptake under some conditions. Miyake and Kawamura demonstrated a maximum energy conversion efficiency (combustion energy of hydrogen gas produced/incident light energy) of 6 to 8% using Rhodobacter sp. in laboratory experiments.
Combined photosynthetic and anaerobic and bacterial hydrogen production
Anaerobic bacteria metabolize sugars to produce hydrogen gas and organic acids, but are incapable of further breaking down the organic acids formed. the combined use of photosynthetic and anaerobic bacteria for the conversion of organic acids to hydrogen. Theoretically, one mole of glucose can be converted to 12 moles of hydrogen through the use of photosynthetic bacteria capable of capturing light energy in such a combined system. From a practical point of view, organic wastes frequently contain sugar or sugar polymers. It is not however easy to obtain organic wastes containing organic acids as the main components. The combined use of photosynthetic and anaerobic bacteria should potentially increase the likelihood of their application in photobiological hydrogen production.
Enhancement of hydrogen-producing capabilities through genetic engineering
Although genetic studies on photosynthetic microorganisms have markedly increased in recent times, relatively few genetic engineering studies have focused on altering the characteristics of these microorganisms, particularly with respect to enhancing the hydrogen-producing capabilities of photosynthetic bacteria and cyanobacteria some nitrogen-fixing cyanobacteria are potential candidates for practical hydrogen production. Hydrogen production by nitrogenase is, however, an energy-consuming process due to hydrolysis of many ATP molecules. On the other hand, hydrogenase-dependent hydrogen production by cyanobacteria and green algae is "economic" in that there are no ATP requirements. This mechanism of hydrogen production is not however sustainable under light conditions. Water-splitting by hydrogenase is potentially an ideal hydrogen-producing system. Asada and co-workers attempted to overexpress hydrogenase from Clostridium pasteurianum in a cyanobacterium, Synechococcus PCC7942, by developing a genetic engineering system for cyanobacteria. These workers also demonstrated that clostridial hydrogenase protein, when electro-induced into cyanobacterial cells is active in producing hydrogen by receiving electrons produced by photosystems .
18MMB015
Question : Cellulolytic microorganisms..
ReplyDeleteAnswer : Trichonympha, Clostridium, Actinomycetes, Bacteroides succinogenes, Butyrivibrio fibrisolvens, Ruminococcus albus, and Methanobrevibacter ruminantium.
18MMB015
Q. Microbiological way to produce hydrogen?
ReplyDeleteAns: In fermentation-based systems, microorganisms, such as bacteria, break down organic matter to produce hydrogen. The organic matter can be refined sugars, raw biomass sources such as corn stover, and even wastewater. Because no light is required, these methods are sometimes called "dark fermentation" methods.
In direct hydrogen fermentation, the microbes produce the hydrogen themselves. These microbes can break down complex molecules through many different pathways, and the byproducts of some of the pathways can be combined by enzymes to produce hydrogen.
Researchers are studying how to make fermentation systems produce hydrogen faster (improving the rate) and produce more hydrogen from the same amount of organic matter (increasing the yield).
Microbial electrolysis cells (MECs) are devices that harness the energy and protons produced by microbes breaking down organic matter, combined with an additional small electric current, to produce hydrogen.
This technology is very new, and researchers are working on improving many aspects of the system, from finding lower-cost materials to identifying the most effective type of microbes to use.
18MBT031
What is immobilization? Name the methods used for microbial cell immobilization.
ReplyDeleteImmobilization is the method of entrapping/attaching the microbial cells in a suitable matrix.
Different methods such as encapsulation, gel entrapment, covalent bonding, cross linking and adsorption is carried out
to prepare immobilized cells.
18MBT028
18MBT034
ReplyDeleteQ. What are the types of steel and their composition.
A. There is four types of the steel based on the different amount of carbon and alloys:
1.Alloys steel
2.Tool steel
3.stainless steel
4.carbon steel
1.Alloy steel: The strength and property of alloy steels depends on the concentration of elements they have.
It is mixture of several metals, including nickel,copper and aluminum.
2.Tool steel
Tool steels are variety of carbon and alloy steels that are particularly well suited to be made into tools.
Their suitability comes from their distinctive hardness, resistance to abrasion and deformation, and their ability to hold a cutting edge at elevated temperatures.
3.Stainless steel
They are shiny, corrosion resistant, and used in many products, including home appliances, backsplashes and cooking utensils.
It has a low carbon content Stainless steel contains the alloy chromium and can also include nickel or molybdenum. Stainless steel is strong and can withstand high temperatures.
4. Carbon steel
Carbon steel is dull and matte in appearance and is vulnerable to corrosion.
Carbon steel can contain other alloys, such as magnesium, silicon and copper. There are three main types of carbon steel: low carbon steel, medium carbon steel, and high carbon steel.
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ReplyDeleteQ. Why hydrogen can not be used as a fuel?
A. 1) Hydrogen burns without any color to indicate a fire. This becomes a problem refueling our vehicle, because the slightest leak at the nozzle can catch fire without any notice. We don’t refuel by simply putting the nozzle in the filler tube.
2) Hydrogen can be generated by: electrolysis of water or burning natural gas.
Both of these methods are energy intensive. If the goal is reducing greenhouse gases, it doesn't work because it just moves the combustion from automobiles to the industrial plants. If the goal is to reduce fuel costs, it doesn't work because the cost of hydrogen generation makes automobile fuels more expensive.
18MBT034
ReplyDeleteQ.What are the methods used for measurement of kla?
A. Methods of kla Measurement can be broadly classified into chemical and physical methods.
1)Physical Method
a.Dynamic method
b.Dynamic gassing-out method
c.Dynamic pressure step method
2) Chemical methods
a. Catechol bio-oxidation method
b. Glucose oxidase method
c. Krypton absorption method
d. Sodium sulfite oxidation method
e. Carbon dioxide absorption method
f. Hydrazine oxidation method
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ReplyDeleteQ.Is there any microbiological process for producing hydrogen gas?
A. There are two basic types of bio hydrogen production processes:
1. Sunlight-driven microbial photosynthetic processes using water or organic substrates.
(the microorganisms used: green microalgae, cyanobacteria
and photosynthetic bacteria)
2. Dark fermentation by heterotrophic bacteria utilizing starches, sugars and other
organic substrates.
(fermentative bacteria are used here)
18MBT034
ReplyDeleteQ. What is immbobilization and what are the methods of immobilization?
A.Method of immobilization involves the 'trapping' of microbial cells on any support or matrix.
Methods involved are:
1) Adsorption
2) Covalent bonding
3) Entrapment
4) Encapsulation
Q:- What is immobilization? and methods of immobilization. Ans:- Immobilization is defined as the imprisonment of cell or enzyme in a distinct support or matrix. The support or matrix on which the enzymes are immobilizer allows the exchange of medium containing substrate or effector or inhibitor molecules. The practice of immobilization of cells is very old and the first immobilized enzyme was amino acylase of Aspergillus oryzae for the production of L-amino acids in Japan. Methods :- Based on support or matrix and the type of bonds involved there are five different methods of immobilization of enzyme or whole cells.1) Adsorption. 2) Covalent bonding. 3) Entrapment. 4) Copolymerization. 5) Encapsulation.
ReplyDeleteFrom 18mmb011
ReplyDeleteQ:- what are the types of steel? Ans:- According to the World Steel Association, there are over,3,500 different grades of steel environmental properties. In essence ,steel is composed of iron and carbon , although it is the amount of carbon,as well as the level of impurities and additional alloying elements that determine the properties of each steel grade. Carbon content .In steel can range from 0.1℅_ 1.5℅,but the most widely used grades of steel contain only 0.1-0.25℅carbon. steels can be broadly categorized into four groups based on their chemical composition . 1) Carbon steels. 2) Alloy steels. 3) stainless steels. 4) stool steels. Low carbon steels contain up to 0.3% carbon ,medium containing 0.3_0.6% carbon and high contain 0.6%. Alloy steels contain alloying elements in varying proportions in order to manipulate the steels properties. Stainless steel generally contain between 10-20% chromium as the main alloying elements and valued for high corrosion resistance. Tools steels contain tungsten , molybdenum, Cobalt and vanadium quantities to increased heat resistance and durability ,making them ideal for cutting and drilling equipment. 18mmb011.
ReplyDeleteQ:- Roles of multiple glucose transporters in S.cerevisiae. Ans:-Growth and carbon metabolism in triosephosohate isomerase (delta tpi1) mutants of S.cerevisiae are severely inhibited by glucose .By using this feature,we selected for secondary site revertant on glucose. We defined five complementation groups,some of which have previously been identified as glucose repression mutants. The predominant mutant type,HTR1 is dominant and causes various glucose specific metabolic and regulatory defects in TPl1 wild type cells .HTR1 mutants are deficient in high affinity glucose uptake and have reduced low affinity transport.Transcription of various known glucose transporter gene (HXT1,HXT3,and HXT4) was defective in HTR1 mutants, leading us to suggest that HTR mutations affect a negative factor of HXTgene expression.by contrast transcript levels for SNF3 ,which encodes a component of high affinity glucose uptake,were unaffected.we presume that HTR1 mutations affect a negative factor of HXT gene expression.multicopy expression of HXT genes or parts of their regulatory sequences the metabolic defects of HTR1 mutants but not their derepressed phenotype at high glucose concentration this suggest that the glucose repression defect is not a direct result of the metabolically relevant defect in glucose transport.Alternatively,some unidentified regulatory components of the glucose transport system may be involved in the generation or transmission of signals for glucose repression. 18mmb011.
ReplyDeleteAre there any microbiological ways for producing hydrogen gas?
ReplyDeleteYes, hydrogen gas can be produced by microbiological methods.
This can be performed by direct biophotolysis and indirect biophtolysis.
(1) Direct biophotolysis:
Cells of certain algae eg. Chlamydomonas reinhardtii, chlorella fusca) or cyanobacteria are capable to split water into molecular hydrogen and oxygen under illumination. This process require absolutely anaerobic conditions.
(2) Indirect biophotolysis:
This process can be performed with certain cyanobacteria (eg. Anabeana variabilis). This method is difficult to perform in industry because of periodicity of process.
The hydrogen yields generated by either direct or indirect photolysis are unfortunately very low in comparison with other fermentative methods.
(a) Photofermentation:
This process is based on decomposition of organic compounds to hydrogen in the presence of both oxygen and nitrogen but in presence of photosynthetic bacteria under illumination. The main advantage of this process rely on the high yield of hydrogen while transforming organic compounds to H2 and CO2.
(b) Dark fermentation:
This process occur in the absence of light. Anearobic microorganisms are generating hydrogen while transforming biodegradable substances under oxygen free conditions. But hydrogen is not the only gaseous product of this process. Carbon dioxide, methane, hydrogen sulfide can be found. Final amount of generated hydrogen depends on many factors including type, and concentration of the substrate, pH value, substrate to innoculum ratio, etc. The relatively high rate of hydrogen production is the important factor influencing possible industrial applications.
ReplyDeleteQTS: Different methods for measurement of kLa
1.sulphite oxidation method
2.Gassing out technique- static and dynamic
3.Oxygen balance technique.
4.enzymatic method
which technique is more efficient?
The oxygen-balance technique appears to be the simplest method for the assessment of kLa and has the advantage of measuring aeration efficiency during a fermentation. The sulphite oxidation and static gassing-out techniques have the disadvantage of being carried out using either a salt solution or an uninoculated, sterile fermentation medium.
sulphite oxidation method is time consuming method.
static gassing out technique is used on small scale only.
In dynamic gassing out technique major limitation in the operation of the technique is the range over which the increase in dissolved oxygen concentration is measured.
In enzymatic method specific enzymes are used but enzymes becomes expensive. Mostly glucose oxidase is used for this.
18mmb013
Stainless steel (more particularly steel 316) still can eventually rust, can get marked by fingerprints, grease but it can withstand much more.
ReplyDeleteIt has relatively higher chromium, and especially molybdenum (alloy) which gives it corrosion resistance (specifically saline or chloride-exposed environments)
Good oxidative resistance in intermittent service to 1600°F (870° C) and in continuous service to 925° C.
Strength (tensile) is 84100 psi
Easily cleanable
Can be welded easily and handled easily.
Polished smooth surface appearance
High tolerance to acid levels
Because of these reasons, steel 316- although costlier than steel 304 -is used majorly in many areas such as industries, medicinal field for surgical instruments, and food industry.
Steel 316 is a molybdenum alloyed steel (16% chromium, 10% nickle,2% molybdenum )
it has greater resistance to corrosion to chloride( hence regarded standard marine grade stainless steel )
good welding characteristics
Tensile strength: 515 MPa
Density:8000 kg/m^3
18mmb013
Question:- Methods of Immobilization
ReplyDeleteAnswer:-
1. Physical immobilization methods:-
》Immobilization by physical method is the earliest form of immobilization,
prepared mainly for the purpose of protein isolation. It method involves of
physical interaction only, where both entities; either immobilizer and immobilization agent are not changed, linked, or modified in order to immobilize them. Several examples of physical immobilization methods preparation are by way of ,
▪encapsulation,
▪entrapment or confinement,
▪adsorption ,
▪non-covalent interaction.
2. Chemical immobilization methods:-
》Whereas in chemical immobilization, chemical reactions are involved in the
preparation to forms either strong bond between both entities. As a result of such chemical reaction, immobilizer biomaterials are either covalently linked or "cross linked" to its immobilization agent’s molecule depends on the type of bond formed.
When specific "covalent bonds" between both entities were established and electron sharing involved, the immobilization is formed as a result of covalent bonding. In cross-linking, an intermediary links both entities by covalent or ionic bonds, thus it is
much stronger than covalent bonds which provides more stability and longer immobilization.
18MMB010
Question:- Newtonian fluids and Non Newtonian fluids
ReplyDeleteAnswer:-
Answer:-
☆NEWTONIAN FLUIDS:-
》A Newtonian fluid's viscosity remains constant, no matter the amount of shear applied for a constant temperature.. These fluids have a linear relationship between viscosity and shear stress.
Examples:
Water
Mineral oil
Gasoline
Alcohol
☆NON-NEWTONIAN FLUID :-
》Non-Newtonian fluids are the opposite of Newtonian fluids. When shear is applied to non-Newtonian fluids, the viscosity of the fluid changes. The behavior of the fluid can be described one of four ways:-
▪Dilatant - Viscosity of the fluid increases when shear is applied. For example:
Quicksand
Cornflour and water
Silly putty
▪Pseudoplastic - Pseudoplastic is the opposite of dilatant; the more shear applied, the less viscous it becomes. For example:-Ketchup
▪Rheopectic - Rheopectic is very similar to dilatant in that when shear is applied, viscosity increases. The difference here, is that viscosity increase is time-dependent. For example:-Gypsum paste,Cream
▪Thixotropic - Fluids with thixotropic properties decrease in viscosity when shear is applied. This is a time dependent property as well. For example:Paint,Cosmetics,Asphalt,
Glue
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what is immobilization?
ReplyDeleteThe technique used for the physical or chemical fixation of cells, organelles, enzymes, or other proteins (e.g. monoclonal antibodies ) onto a solid support, into a solid matrix or retained by a membrane, in order to increase their stability and make possible their repeated or continued use.
There are four principal methods available for immobilising enzymes.
adsorption
covalent binding
entrapment
membrane confinement
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ReplyDeleteQUESTION: Industrial centrifuge and its principle.
ReplyDeleteAns: Definition-Industrial centrifuge is used to separate heterogeneous mixtures into components varying by density.
Its Principle- This centrifuge rotates at a high speed,with many revolutions per minute(rpm).This rotation introduces a centripetal force inward and a relative centrifugal force outward.This relative centrifugal force is hundreds of times greater than the force of gravity we feel on earth.We know from everyday experience that a heterogeneous mixture of solid in liquid,when given enough time, we will separate due to gravity and result in a sediment at the bottom of the container.The same principle is at work inside the industrial centrifuge but the high centrifugal force causes the separation to occur within minutes.
Roll no.-18mmb020
Q:- Types of industrial centrifuge.
ReplyDeleteans: Two main types of industrial centrifuge:
1) Sedimentation centrifuge- in sedimentation centrifuge the higher density particles are forced to outer edges of the container where they force a closely packed pellet.
2) Filter centrifuge- there is a filter which catches particles and prevents them from following the rest of the mixture outward as the centrifuge spins.
Eg: food industry include production of pulp-free orange juice and the removal of water from washed salads prior to packaging.
Roll no. -18mmb020
Various methods for the measurement of kLa
ReplyDelete-chemical method
-Dynamic Differential Gassing-Out method (DDGO)
-Dynamic Integral Gassing-Out method (DIGO(
-Oxygen Balance method (OB)
-Enzymatic methods (GGO)
Roll no -18MMB019
Names of organisms which are able to degrade cellulose
ReplyDelete-Trichonympha
-Clostridium
-Actinomycetes
-Bacteroids succinogens
-Butyrivibrio fibrisolvens
-Ruminococcus albus
-Methanobrevibacter ruminantium
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INDUSTRIAL CENTRIFUGE:
ReplyDeleteAn industrial centrifuge is a machine used for fluid/particle separation. Centrifuges rely on the use of centrifugal force, generating several hundreds or thousands of times earth’s gravity. The law of physics governing centrifugal separation is known as Stokes Law.
The industrial centrifuge plays an integral role in the production of more things than one would initially expect. It is a commonly used tool in the food and agricultural sector, at pharmaceutical and biotechnology companies, for environmental management, and in the chemical industry.
They are used for separating solids from liquids, liquid-liquid separation, and liquid-liquid-solid separation.
(18MBT028)
EXPLAIN TYPES OF INDUSTRIAL CENTRIFUGES.
ReplyDeleteThere are two groups of centrifuges for liquid-solid separation: (1) Filtering centrifuges and (2) Sedimenting centrifuges.
Purchas (1981) has given full account of the designs and applications of each type. The major difference between the two is that the former utilizes a perforated bowl through which the fluid (centrate) can pass while the solids are retained inside the bowl. The latter is equipped with a solid (impermeable) bowl, and separation of the fluid is done by forcing it to overflow from the bowl while the solids are retained on its walls. The method of transport of solids and the control of liquid flows can vary widely in both types of centrifuge, and these factors are the ones generally used to subclassify the different machines.
2) Sedimenting centrifuges:
Sedimenting centrifuges remove solids from liquids by causing the particles to migrate radially towards the walls of the centrifuge bowl.
The basic types of centrifuges in this category are:
a) the high speed, tubular bowl type with manual discharge of solids;
b) the skimmer pipe/knife discharge types;
c) the disc-type centrifuge; and
d) the continuous scroll discharge machines
This comment has been removed by the author.
ReplyDeleteQ MERITS AND DEMERITS OF SOLID STATE FERMENTATION ?
ReplyDeleteA MERITS:
1. higher and reproducible product yield
2. simple technology
3. low moisture reduces the problem of contamination
4.products may be incorporated directly into the animal feeds
5. use of small fermentation vessels
DEMERITS
1. Difficulty in mixing - low in homogeneous
2. difficulty in temperature control- by low conductivity
3.the addition of water in early fermentation may increase the risk of contamination
4. slower microbial growth
Q methods for the measurement of kLa
A 1. chemical method also known as sulfite oxidation method.
2. Dynamic Differential Gassing-Out (DDGO) Method
3. Dynamic Integral Gassing-Out (DIGO) Method
4. Oxygen Balance (OB) Method
5. Enzyme Method - using glucose glucose oxidase system
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QUESTION. Different methods for measurement of kLa?
ReplyDeleteANS. 1.enzymatic method
2.Gassing out technique- static and dynamic
3.Oxygen balance technique.
4.sulphite oxidation method
What is an Industrial Centrifuge?
ReplyDeleteAn industrial centrifuge is a machine used for fluid/particle separation. Centrifuges rely on the use of centrifugal force, generating several hundreds or thousands of times earth’s gravity. The law of physics governing centrifugal separation is known as Stokes Law. Industrial centrifuges are used for separating solids from liquids, liquid-liquid separation, and liquid-liquid-solid separation.
Industrial centrifuges can be classified into two main types:
sedimentation and filtering centrifuges. Sedimentation centrifuges use centrifugal force to separate solids from liquids, as well as two liquids with different specific gravities. Sedimentation centrifuges include decanter, disk-stack, solid-bowl basket and tubular bowl centrifuges. Filtering centrifuges use centrifugal force to pass a liquid through a filtration media, such as a screen or cloth while solids are captured by the filtering media. Filtering centrifuges primarily deal with perforate basket, pusher and peeler centrifuges. These centrifuges are used in a wide variety of process industries which can be divided into several categories:
♦ Wastewater processing deals with separation of municipal, farm, DAF (dissolved air flotation), trap grease, drilling mud, and environmental wastewater sludges.
♦ Chemical processing which produces raw products such as acids, salts, oil refinery by-products, polymers, oil-water-solids, and so on.
♦ Pharmaceutical and Biotechnology industries that manufacture drugs, vaccines, medicines, penicillin, mycelia, E-coli bacteria, algae, enzymatic waste, etc.
♦ Fuel and Biofuel industry including synthetic fuels, biodiesel, ethanol, cellulosic ethanol, algae biomass dewatering; fuel and lube oil purification, etc.
♦ Food Processing which deals with refining of vegetable oils, dairy (milk, cheese, etc.); poultry, swine and beef rendering; yellow, white, and brown grease separation; fruit and vegetable juice; beer, wine and liquor clarification, etc.
♦ Mining and mineral processing including coal, tar sands, copper, precious metals, calcium carbonate, kaolin clay, and many more.
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Question:- Production of Hydrogen gas by microbiological way.
ReplyDeleteAnswer:-
▪Photofermentation:-
It is carried out by nonoxygenic photosynthetic bacteria that use sunlight and biomass to produce hydrogen. Purple non-sulfur bacteria and green sulfur bacteria are capable of producing hydrogen gas by using solar energy and reduced compounds.
▪Dark-fermentation:-
In fermentation-based systems, microorganisms, such as bacteria, break down organic matter to produce hydrogen. The organic matter can be refined sugars, raw biomass sources such as corn stover, and even wastewater. Because no light is required, these methods are sometimes called "dark fermentation" methods.
▪Microbial electrolysis cell (MEC):- represents an alternative electrically driven H2 production process, which facilitates the conversion of electron equivalents in organic compounds to H2 gas by combining microbial metabolism with bioelectrochemical reactions. Low-energy consumption compared to conventional water electrolysis, high product (H2) recovery, and substrate degradation than the dark fermentation process are some of the potential benefits that make MEC an alternate process.
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Question:- type of centrifuge
ReplyDeleteAnswer:-
All modifications of centrifuges can be distinguished into two main types: sedimentation and filtering centrifuges. In sedimentation centrifuges the centrifugal force is used to separate solids from liquids or two liquids with different densities. Sedimentation centrifuges include decanter, disk-stack, solid-bowl basket and tubular bowl centrifuges, which will be described below. Filtering centrifuges use centrifugal force to pass a liquid through a filtration media, such as a screen or cloth while solids are captured by the filtering media.
☆Sedimentations centrifuges:-
▪Disc bowl centrifuge or disc stack centrifuge :-
》It was first invented in order to separate cream in milk production industry. These centrifuges usually used for separation of two liquids or liquid and relatively low suspended solid phase. This centrifuge is composed by a vertical rotor with several conical discs on it. These systems of conical spacers allow to increase the
sedimentation area. During rotation, centrifugal forces make denser solids move towards the bowl of the centrifuge where they then can be collected.
▪Decanter centrifuge:-
》Which consists out of a horizontally oriented bowl in a shape of a cone with a conveying scroll inside. The main working principle is related to the differences of densities of the liquids as denser liquids will drop to the bottom wall of the centrifuge. Conveying scroll creates a liquid pool, solids settle to the bowl wall and then transported by a conveying scroll to the end of a bowl where they are collected, whereas less denser liquid returns back to the pool. To prevent accumulation of solid particles on the scroll and reach optimal retention time for the separation, difference in
rotational speeds of bowl and scroll is used in decanter centrifuges.
▪Hydrocyclone :-
》It differs from other sedimentation centrifuges so that it does not have any rotation parts. The centrifugal force form, when suspension is pumped to colon with high speed. Because of the shape of the colon the suspension start to swirl, which occur the separation of the solid particles to the walls of the colon. The liquid material stays in the centre of the colon. The solid particles are removed of the bottom of the colon and clarified liquid material in the top. Hydrocyclones is generally used in continuous processes.
▪Solid-bowl centrifuge :-
》It is a good example about the batch-type centrifuge. It consists of the
one basket and it is generally used of collection particles of low concentration suspensions. In addition, it is also a good method to separate fine particles from liquid material, because of large diameter and high g forces.
☆Filtration centrifuges:-
》Filtration centrifuges similar as sedimentation centrifuges, but they are based on the filtration of the liquid material. Mechanism of the filtration centrifuge is the same as in other centrifuges thus the separation is based on the centrifugal force. The difference is that filtration centrifuges has the filtration material, for example slots, holes, a porous membrane or filtrate cloth depending of the application and the purpose of the of the process.
18MMB010
Question:-method of Measurement of kLa.
ReplyDeleteAnswer:-
1. Chemical Method(The chemical method is known as the sulfite oxidation method.)
2. Dynamic Differential Gassing-Out (DDGO) Method.
3. Dynamic Integral Gassing-Out (DIGO) Method.
4. Oxygen Balance (OB) Method
5. Enzymic Method (GGO).
18MMB010
QUE - Methods for measurement of kLa
ReplyDelete1. Chemical Method:
The chemical method is known as the sulfite oxidation method.
It involves the determination of the maximum rate of oxidation of sodium sulfite to sodium sulfate in the presence of c0so4 or CuSO4 catalyst, in which there is no back pressure of dissolved oxygen.
2. Dynamic Differential Gassing-Out (DDGO) Method:
This method, developed by Bandyopadhyay et al., is based on following the DO trace during a brief interruption of aeration in the fermentation system.
3. Dynamic Integral Gassing-Out (DIGO) Method:
The differential gassing-out method has been widely used.
4. Oxygen Balance (OB) Method:
Some investigators are of the opinion that oxygen balance over the whole system is the best method for evaluation of KLa in fermenters, because no assumption need be made on the effects of cell, surface active agents, viscosity, and forth. Based on the oxygen balance concept, Mukhopadhyay and Ghose developed a linear mathematical correlation between DO concentration and the proportion of oxygen in inlet and exit air of laboratory fermenter from which KLa can be determined very easily and rapidly.
5. Enzymic Method (GGO):
Based on the Heineken theory, Linek and his associates ‘ developed a dynamic method to determine KLa in a fermenter using the glucose-glucose oxidase (GGO) system. Assuming absorption of oxygen in the liquid phase as the first-order reaction as well as perfect mixing conditions.
18MMB005
QUE -Types of industrial centrifuge
ReplyDeleteThere are two main types of industrial centrifuges: sedimentation centrifuges and filter centrifuges. In the sedimentation centrifuge the higher density particles are forced to the outer edges of the container where they force a closely packed pellet. In filter centrifuges there is a filter which catches particles and prevents them from following the rest of the mixture outward as the centrifuge spins. A couple of examples of filter centrifugation in the food industry inclued the production of pulp-free orange juice and the removal of water from washed salads prior to packaging.
Other uses for the industrial centrifuge include the recovery of cells in biotechnology and the recovery of valuable pharmaceutical reactants and products. Centrifugation is used for wastewater treatment and sewage processing. It is used to remove particulates like metal shavings from industrial lubricants. It is important for the isolation of valuable synthetic materials throughout the manufacturing process. The centrifuge makes it possible for many materials to be manufactured on the industrial scale because it allows for the rapid separation of mixtures. There are different types of centrifuges for different applications, and the optimal rpm varies among mixtures, but the basic principle of centripetal acceleration is useful for all applications. We can create great things when we understand fundamental physical laws and engineer tools to capitalize upon them.
18MMB005
Name the Commercial name of combination AMOXYCILLIN + CLAVULINIC ACID.
ReplyDeleteCo-amoxiclav.
Trade names for amoxicillin/clavulanate include Augmentin, Clavamox, and CLAMP.
(18MBT028)
Merits and demerits of Solid state fermentation.
ReplyDeleteMerits:
1.Requires very less technology or instrumentation.
2.Capital investment required is very low.
3.Energy expenditure will be low.
4.Sterilization of the media is not required.
5.Chance of microbial contamination is very less.
Demerits:
1.Precise monitoring and accurate regulation of the fermentation process is not possible with SSF.
2.The growth rate of microbes on solid substratum is relatively slow.
3.Scale-up of the fermentation process is difficult.
4.Fermentation usually produces excessive heat in the medium.
Commercial name of combination of Ampicillin and Clavulanic Acid is Co -amoxiclave.
ReplyDeleteAnd it sold in market name as Augmenting or Clavulanic with different concentrations like
Amoxicillin 200mg + Clavulanic Acid 28.5mg/5mL
Amoxicillin 250mg + Clavulanic Acid 125mg
Amoxicillin 500mg + Clavulanic Acid 125mg
Amoxicillin 400mg + Clavulanic Acid 57mg/5mL
Amoxicillin 1g + Clavulanic Acid 0.2g
(18mbt021)
18MBT034
ReplyDeleteQues: What is the commercial name of combination of amoxycillin and clavulinic acid?
Ans: co-amoxiclav (antibiotic used used to treat bacterial infections).
Brand name: Augmentin.
Q what is the commercial name of amoxicillin and clavulonic acid?
ReplyDeleteA amoxyclav625 is the commercial name of the combination of amoxicillin and clavulonic acid.
18mbt015
Q what are the methods of measuring kla?
ReplyDeleteA 1 Chemical Method:
The chemical method is known as the sulfite oxidation method.
It involves the determination of the maximum rate of oxidation of sodium sulfite to sodium sulfate in the presence of c0so4 or CuSO4 catalyst, in which there is no back pressure of dissolved oxygen.
The reaction is independent of sulfite concentration in the range of 0.8 M to 0.02 M. usually, 0.5-0.8 M sodium sulfite solution at pH 7.5-7.8 is used in KLa determination. The course of oxidation is followed by analyzing the unreacted sulfite concentration, using the excess of standard iodine, and back- titrating the unreacted iodine with sodium thiosulfate solution.
2 Dynamic Differential Gassing-Out (DDGO) Method:
This method, developed by Bandyopadhyay et al., is based on following the DO trace during a brief interruption of aeration in the fermentation system. Only a fast-response, sterilizable DO probe is needed to obtain the necessary data.
The experimental procedure involves degassing (air turn-off) of an actively respiring fermentation mash to record the decrease in DO concentration due to respiration and to obtain the rate of oxygen uptake by the total cell mass. Before critical DO concentration of the organism is reached, aeration is resumed and the increase in DO concentration is recorded as a function of time. The rate of change of DO concentration is measured from this trace.
3 Dynamic Integral Gassing-Out (DIGO) Method:
The differential gassing-out method has been widely used, but it may incorporate several weak points.For improving some of these weak points, Fujio et al. developed a dynamic integral gassing-out technique based on the differential gassing-out method. Basically, the experimental procedure is the same as that in the previous method.
However, in the case of low DO concentration in equilibrium in microbial cultivation, if one takes the integral form of equation. 5.71, more accurate values will be provided for rCx and dCL/dt, and hence for KLa. The value of rCx in equation 5.71 may be regarded as having a constant value during a short period of time.
4 Oxygen Balance (OB) Method:
Some investigators are of the opinion that oxygen balance over the whole system is the best method for evaluation of KLa in fermenters, because no assumption need be made on the effects of cell, surface active agents, viscosity, and forth. Based on the oxygen balance concept, Mukhopadhyay and Ghose developed a linear mathematical correlation between DO concentration and the proportion of oxygen in inlet and exit air of laboratory fermenter from which KLa can be determined very easily and rapidly, as described below.
When air is blown to a fermentation mash, a fraction of oxygen present in incoming air is dissolved in the liquid, from which the microorganisms absorb oxygen for their respiration and metabolic activities and unabsorbed oxygen goes out with the exit gas. Assuming that during fermentation air density in inlet and exit air does not change appreciably, the incoming air flow rate is equal to the outgoing flow rate (i.e., the pressure drop in the vessel is very low and evaporation loss of the medium is negligible), one can make an oxygen balance in the aerobic bioprocessing system at any time.
18mbt015
Q Merits and Demerits of solid state fermentation (ssf)?
ReplyDeleteA Solid state fermentation is also called substrate state fermentation. Here microorganisms are grown in near absence of free water.
Merits of SSF are:
Ø SSF requires only simple nutrient media as the substrate.
Ø Requires very less technology or instrumentation.
Ø Capital investment required is very low.
Ø Energy expenditure will be low.
Ø Sterilization of the media is not required.
Ø Chance of microbial contamination is very less.
Ø Downstream processing (purification of products) is very easy.
Ø The yield is usually very high.
Ø The design of bioreactor is very simple.
Ø A variety of natural substrates can be used.
Ø Domestic, agricultural and industrial wastes can be efficiently used as substrate in SSF and useful products can be generated from them.
Ø Low waste water generation
Ø No problem with foaming
Ø Sporulation of some fungi can only be attained by SSF since these fungi do not sporulate in liquid medium (Example: Coniothyrium minitans – a biocontrol agent).
Ø Resembles the natural habitat of microbes.
However solid state fermentation has some demerits too like:
Only those microbes that can survive in low moisture condition can be used in SSF.
Ø Precise monitoring and accurate regulation of the fermentation process is not possible with SSF.
Ø The growth rate of microbes on solid substratum is relatively slow.
Ø Scale-up of the fermentation process is difficult.
Ø Fermentation usually produces excessive heat in the medium.
Ø The environmental conditions of the microbes cannot be regulated in SSF.
Ø Bacterial contamination sometimes problematic.
18mbt015
In Industry there is more use of Batch fermentation than Continuous fermentation. Why?
ReplyDeleteBatch fermentation is easy to set up than continuous fermentation.
In continuous Fermentation it requires sophisticated instrumentation.
Batch fermentation is more suitable for the production of secondary metabolites like Antibiotics. In Batch Fermentation, Less investment is required and Labour demand is also less and , after the fermentation is over, the residues are taken out from the fermentation tank, and vessel is then cleaned and sterilized before next batch of fermentation so that Chance of contamination is less .
• Recently, thousands of migratory birds died at
ReplyDeleteSambhar lake in Rajasthan due to Avian botulism.
• It is caused by a bacterium called Clostridium
botulinum.
• It affects the nervous system of birds, leading to
flaccid paralysis in their legs and wings and neck.
• It is found that biological oxygen demand in sambhar
lake is above permissible limits, this led to rise of
Clostridium botulinum.
o Clostridium botulinum are heat-resistant and in
the absence of oxygen they germinate, grow and
then excrete toxins.
Zoological Society of London (ZSL) scientists used plants to
ReplyDeletepower sensors in the wild by installing microbial fuel cells.
About Microbial fuel cells
• A microbial fuel cell (MFC) is a bio-electrochemical device
that harnesses the power of respiring microbes to convert
organic substrates directly into electrical energy.
• It transforms chemical energy into electricity using
oxidation reduction reactions
• It relies on living biocatalysts to facilitate the movement of
electrons throughout their systems instead of the
traditional chemically catalyzed oxidation of a fuel at the
anode and reduction at the cathode.
• It has various application especially where there is low
power requirement where replacing batteries may be impractical, such as wireless sensor networks,
biosensors etc.
"""
How do Microbial Fuel Cells Work?
• Microbial fuel cells work by allowing bacteria to oxidize and reduce organic molecules.
• Bacterial respiration is basically one big redox reaction in which electrons are being moved around.
o An oxidation-reduction (redox) reaction is a type of chemical reaction that involves a transfer of
electrons between two species.
• Whenever you have moving electrons, the potential exists for harnessing an electromotive force to
perform useful work.
• A MFC consists of an anode and a cathode separated by a cation specific membrane.
• Microbes at the anode oxidize the organic fuel generating protons which pass through the membrane to the
cathode, and electrons which pass through the anode to an external circuit to generate a current.
• The trick of course is collecting the electrons released by bacteria as they respire."""""""
This comment has been removed by the author.
ReplyDeleteACID FERMENTATION :-
ReplyDeletePropionibacterium species are tested for commercial-scale pro- duction of propionic acid. Propionic and other acids are synthesised in anaerobic culture using sucrose as substrate and ammonia as nitrogen source. Overall yields from sucrose are as follows:
propionic acid 40% (w/w)
acetic acid 20% (w/w)
butyric acid 5% (w/w)
lactic acid 3.4% (w/w)
biomass 12% (w/w)
Bacteria are inoculated into a vessel containing sucrose and ammonia; a total of 30 kg sucrose is consumed over a period of 10 days.
Production of bakers' yeast Bakers' :-
ReplyDeleteYeast is produced in a 50,000-litre fermenter under aerobic conditions. The carbon substrate is sucrose; ammonia is provided as nitrogen source.
The average biomass composition is CH-1.83, O-0.55, N0-.17 with 5% ash. Under efficient growth conditions, biomass is the only major product; the biomass yield from sucrose is 0.5 g g-1.
If the specific growth-rate is 0.45 Per hr, estimate the rate of heat removal required to maintain constant temperature in the fermenter when the yeast concentration is 10 gram per litre.