These are the substances involved in the passive mediated transport ( or facilitated diffusion) of ions across membranes. They vastly increase the permeability of membranes to particular ions. They transport ions along the concentration gradients.
Ionophores are Organic molecules of diverse types, many of which are antibodies of bacteria origin. Cells and organelle actively maintain concentration gradients of various ions across their membranes (e.g., Na+, K+ - pump). The antibiotic properties of ionophores arise from their tendency to discharge these concentration gradient.
Thursday, December 3, 2009
Tuesday, December 1, 2009
Ceruloplasmin.
About 90% of copper circulating in the blood of normal mammals present as an intensely blue colored protein called Ceruloplasmin. This protein is responsible for the storage and transport of copper. It is synthesized in liver. In addition to blood, it is also found in spinal fluid, joint fluid and gastrointestinal secretion.
Ceruloplasmin is a glycoprotein. The copper atoms are an integral point of Ceruloplasmin structure. There are 7-8 copper atoms per molecule. One half of the copper in crystalline Ceruloplasmin is in Cu2+ state. All these Cu2+ ions are not equivalent. The other half of copper remain in the Cu+ state.
The Cu2+ ions of Ceruloplasmin are reduced by Fe2+ and oxidised by molecular O2 in a cyclic process, called Ferroxidase activity. Ceruloplasmin oxidise (+ve state of ) Fe2+ to Fe3+, which then bind to transferrin.
Patent's suffering from wilson's disease may exhibit masked deficiency of Ceruloplasmin. This copper deficiency inhibits haemoglobin bio synthesis and ultimately leads to death.
Ceruloplasmin is a glycoprotein. The copper atoms are an integral point of Ceruloplasmin structure. There are 7-8 copper atoms per molecule. One half of the copper in crystalline Ceruloplasmin is in Cu2+ state. All these Cu2+ ions are not equivalent. The other half of copper remain in the Cu+ state.
The Cu2+ ions of Ceruloplasmin are reduced by Fe2+ and oxidised by molecular O2 in a cyclic process, called Ferroxidase activity. Ceruloplasmin oxidise (+ve state of ) Fe2+ to Fe3+, which then bind to transferrin.
Patent's suffering from wilson's disease may exhibit masked deficiency of Ceruloplasmin. This copper deficiency inhibits haemoglobin bio synthesis and ultimately leads to death.
Monday, November 30, 2009
Supramolecular Chemistry.
Supra-molecular chemistry is a branch of chemistry concerned with the aggregation of molecules into large assemblies. The molecules in the assembly are held by the weak intermolecular forces such as hydrogen bonding, dipolar, Vander Waal's and hydrophobic interaction and also metal ion coordination. Just as in a molecule atoms are held together by strong covalent bonds, in Supra-molecular structure, molecules are held together by weak intermolecular forces. It is often described as chemistry beyond the molecule.
Supra-molecular chemistry involves self-assembly or spontaneous association of several (2 or more) molecular components into a discrete non-covalently bound aggregate with a well defined structure. When highly complex structures are obtained from such units, the process is sometimes called self-organization.
Self assembly involves molecular recognition processes (binding events). Molecular recognition relies upon complementary of size, shape and chemical functionalities.
The partners of supra-molecular species have been named molecular receptor and substrate. The substrate usually being the smaller component whose binding is being sought. It is also sometimes called host-guest interaction. The binding of a substrate S to a receptor R yields the supra-molecule RS and involves a molecular recognition process. In order to achieve high recognition it is desirable that the receptor and substrate be in contact over a large area. This occur when the receptor is able to wrap around its guest so as to establish numerous non-covalent binding interactions and to sense its molecular size, shape and architecture.
In addition to binding sites, the receptor also carries reactive functions, it may effect chemical transformation on the bound substrate, thus behaving as a supra-molecular catalyst.
A lipophilic membrane soluble receptor may act as a carrier effecting the translocation of the bound substrates across the membrane. Thus, molecular recognition, transformation and translocation represent some of the basic functions of supra-molecular species. Supra-molecular chemistry has thus contributed in the construction of receptors, transfer agents enzyme models and extended arrays.
The concepts of the molecular recognition and complementarity are common in biological systems. complementarity between H-bonding groups on the twin strands of DNA is what makes the double helix stable. Molecular recognition is also part of the so called 'lock and Key' mechanism of enzyme action and transport of ions across membranes.
Supra-molecular chemistry first synthetic receptors were able to recognize the simplest of the substrates, the alkali metal ions. Receptors that recognize these ions already exist in nature. An example is the ionophore valinomycin which is a cyclic peptide molecule that binds specifically K+ ions and transports them across cell membranes. Valinomycin's ability to recognize and bind K+ ions selectivity is due to its geometrical complementarity, the cavity being of the rigid size to bind K+ ions. Na+ ions are smaller and are not bound by valinomycin. In addition to geometrical complementarity, valinomycin is a good receptor because of the presence of several interaction sites (Carbonyl groups) so that strong binding is possible.
It was the search of the synthetic analogues of natural ionophores that led to the discovery of cyclic ethers or crown ethers as receptors for metal ions (pederson). Crown ethers contain oxygen atoms in a cyclic structure with a central cavity with right size to fit the target ion. e.g., 18-crown-6 and 15-crown-5
In 18-crown-6 a cavity of the right size to fit K+ ions. It can, therefore, recognise and selectively bind to K+.
Subsequently, bicyclic molecules were synthesized in which nitrogen atoms unite three ether chains. These receptor molecules are three dimensional receptors with roughly spherical cavities, that bind alkali metal ions more tightly than do the single ring crown ethers. These molecules were called Cryptands and their metal complexes Cryptates. The metal ion binding ability of cryptands is selective, i.e, they exhibit molecular recognition. The selectivity is dependent on the size of the cavity.
Tricyclic receptors have also been developed which could bind large cations such as Cs+ and also NH4+ ions in their cavity.
In all these systems, the preference for a particular metal ion depends on a subtle balance between several thermodynamic factors.
a) binding energy (enthalpy)
b) gain or loss of configurational freedom (entropy) when the solvent cage of the metal ion is replaced by the ether cage.
This is characteristic of all supra-molecular complexes.
The Crown ethers and Cryptands highlighted the features that help good molecular recognition of a substrate by a receptor and helped in the construction of new receptors. They showed forinstance, how increasingly strong selective binding results from an increasing degree of pre-organization of binding groups in the receptor.
Receptor molecule with rigid cavities have the advantage that the binding sites are already in place before a substrate is bound. The binding sites donot have to organize themselves during the process of binding. In other words, they have a high degree of pre-organization and hence exhibit good molecular recognition properties such receptor molecules with relatively rigid cavities are known in nature of particular interest is the class of naturally occurring carbohydrates called Cyclodextrins, alpha-, beta-, and gamma- which contains 6, 7 and 8 glucose units respectively, linked head to tail in a ring. These molecules have a cylindrical cavity running through their centre in which small molecules can fit. The outer face of a cyclodextrin is hydrophilic with hydroxyl groups that have H-bonding ability so that the molecule is soluble in water. The inner cavity is lined mainly with C-C and C-H groups and is hydrophobic. Hence the cavity is able to receive and bind hydrophobic molecules such as benzene and phenylmethyl ether. Such receptor-substrate complexes are also called host-guest complexes or inclusion complexes. The molecular recognition in them is governed by complementarity of size and affinity (hydrophobicity) between cyclodextrin cavity and the molecule. Cyclodextrins have been investigated as enzymes mimics that enhance the selectivity of a chemical transformation carried out on the bound substrate. It was found that the H-atoms of the benzene ring of phenyl methyl ether could be substitued by chlorine specifically in the para position when the molecule was bound with a cyclodextrin. Only the para-hydrogen protruding from the bottom of the cavity was exposed to chlorine attack.
Synthetic rigid cavity receptors are also known. For example, formaldehyde and phenol derivatives can form cyclic oligomers which adopt a cup-like shape and are called calixarenes. Synthetic methods of making a wide range of calixarenes with different numbers of phenolic groups in the calix(n)arenes, where n denotes the number of phenol groups in the ring. For e.x., calix(4)arene has four phenol groups in the ring. The lining of benzene rings in the bowl shaped cavities of calixarenes allows them to acts as 'molecular baskets' for hydrophobic substrate like toluene, benzene and xylene.
The strength with which the substrate is bound depends on the complementarity of size. For e.x., toluene is firmly embedded in the bowl of a calix(4)arene but it is only loosely bound in the large cavity of calix(8)arene. It has been found that calix(7)arene will exhibit molecular recognition towards carbon cage fullerene molecules C60 and C70. The former with a soccer ball shape is bound tightly in the cavity, whereas the latter, with a rugby ball shape, is not. This provides a means of separating the two molecules which are generally formed in an intimate mixture.
Metal ions can serve as templates, that guide ligands into a particular arrangement. They, there by, act as organizing centers for synthesis of large supra-molecular assemblies from many component parts. In other words metal templation offers an effective approach to the self assembly of recognition sites.
Metal ions that form 4 coordinate square complexes are well suited to act as 90degree corners of square supra-molecular structures.
Metal ions with tetrahedral coordination geometries have been used as organizing centers for the multistep assembly of double helices (helicates). The two ligands twist around several metal ions in a double helical fashion. The two strands in these contain metal bound bipyridine units linked together. The efficiency of the self assembly process is the result of positive co-operativity, whereby the binding of one metal ion pre-organizes the ligands to facilitate the binding of the second. In other words, the assembly process gets easier as it progresses.
Similar strategies have been used to obtain molecular assemblies described as catenanes and rotaxanes. An assembly in which one ring is linked through another is called a catenane. A rotaxane is a linear molecule threaded through a cyclic molecule. Unthreading is prevented by subsequently adding bulky end caps.
One of the goals of supra-molecular chemistry is to build synthetic systems that carry out some of the functions of biochemical systems - trans membrane ion transport, enzyme -like catalysis, conducts for channeling electrons and chemical sensors with high sensitivity and selectivity.
Supra-molecular chemistry involves self-assembly or spontaneous association of several (2 or more) molecular components into a discrete non-covalently bound aggregate with a well defined structure. When highly complex structures are obtained from such units, the process is sometimes called self-organization.
Self assembly involves molecular recognition processes (binding events). Molecular recognition relies upon complementary of size, shape and chemical functionalities.
The partners of supra-molecular species have been named molecular receptor and substrate. The substrate usually being the smaller component whose binding is being sought. It is also sometimes called host-guest interaction. The binding of a substrate S to a receptor R yields the supra-molecule RS and involves a molecular recognition process. In order to achieve high recognition it is desirable that the receptor and substrate be in contact over a large area. This occur when the receptor is able to wrap around its guest so as to establish numerous non-covalent binding interactions and to sense its molecular size, shape and architecture.
In addition to binding sites, the receptor also carries reactive functions, it may effect chemical transformation on the bound substrate, thus behaving as a supra-molecular catalyst.
A lipophilic membrane soluble receptor may act as a carrier effecting the translocation of the bound substrates across the membrane. Thus, molecular recognition, transformation and translocation represent some of the basic functions of supra-molecular species. Supra-molecular chemistry has thus contributed in the construction of receptors, transfer agents enzyme models and extended arrays.
The concepts of the molecular recognition and complementarity are common in biological systems. complementarity between H-bonding groups on the twin strands of DNA is what makes the double helix stable. Molecular recognition is also part of the so called 'lock and Key' mechanism of enzyme action and transport of ions across membranes.
Supra-molecular chemistry first synthetic receptors were able to recognize the simplest of the substrates, the alkali metal ions. Receptors that recognize these ions already exist in nature. An example is the ionophore valinomycin which is a cyclic peptide molecule that binds specifically K+ ions and transports them across cell membranes. Valinomycin's ability to recognize and bind K+ ions selectivity is due to its geometrical complementarity, the cavity being of the rigid size to bind K+ ions. Na+ ions are smaller and are not bound by valinomycin. In addition to geometrical complementarity, valinomycin is a good receptor because of the presence of several interaction sites (Carbonyl groups) so that strong binding is possible.
It was the search of the synthetic analogues of natural ionophores that led to the discovery of cyclic ethers or crown ethers as receptors for metal ions (pederson). Crown ethers contain oxygen atoms in a cyclic structure with a central cavity with right size to fit the target ion. e.g., 18-crown-6 and 15-crown-5
In 18-crown-6 a cavity of the right size to fit K+ ions. It can, therefore, recognise and selectively bind to K+.
Subsequently, bicyclic molecules were synthesized in which nitrogen atoms unite three ether chains. These receptor molecules are three dimensional receptors with roughly spherical cavities, that bind alkali metal ions more tightly than do the single ring crown ethers. These molecules were called Cryptands and their metal complexes Cryptates. The metal ion binding ability of cryptands is selective, i.e, they exhibit molecular recognition. The selectivity is dependent on the size of the cavity.
Tricyclic receptors have also been developed which could bind large cations such as Cs+ and also NH4+ ions in their cavity.
In all these systems, the preference for a particular metal ion depends on a subtle balance between several thermodynamic factors.
a) binding energy (enthalpy)
b) gain or loss of configurational freedom (entropy) when the solvent cage of the metal ion is replaced by the ether cage.
This is characteristic of all supra-molecular complexes.
The Crown ethers and Cryptands highlighted the features that help good molecular recognition of a substrate by a receptor and helped in the construction of new receptors. They showed forinstance, how increasingly strong selective binding results from an increasing degree of pre-organization of binding groups in the receptor.
Receptor molecule with rigid cavities have the advantage that the binding sites are already in place before a substrate is bound. The binding sites donot have to organize themselves during the process of binding. In other words, they have a high degree of pre-organization and hence exhibit good molecular recognition properties such receptor molecules with relatively rigid cavities are known in nature of particular interest is the class of naturally occurring carbohydrates called Cyclodextrins, alpha-, beta-, and gamma- which contains 6, 7 and 8 glucose units respectively, linked head to tail in a ring. These molecules have a cylindrical cavity running through their centre in which small molecules can fit. The outer face of a cyclodextrin is hydrophilic with hydroxyl groups that have H-bonding ability so that the molecule is soluble in water. The inner cavity is lined mainly with C-C and C-H groups and is hydrophobic. Hence the cavity is able to receive and bind hydrophobic molecules such as benzene and phenylmethyl ether. Such receptor-substrate complexes are also called host-guest complexes or inclusion complexes. The molecular recognition in them is governed by complementarity of size and affinity (hydrophobicity) between cyclodextrin cavity and the molecule. Cyclodextrins have been investigated as enzymes mimics that enhance the selectivity of a chemical transformation carried out on the bound substrate. It was found that the H-atoms of the benzene ring of phenyl methyl ether could be substitued by chlorine specifically in the para position when the molecule was bound with a cyclodextrin. Only the para-hydrogen protruding from the bottom of the cavity was exposed to chlorine attack.
Synthetic rigid cavity receptors are also known. For example, formaldehyde and phenol derivatives can form cyclic oligomers which adopt a cup-like shape and are called calixarenes. Synthetic methods of making a wide range of calixarenes with different numbers of phenolic groups in the calix(n)arenes, where n denotes the number of phenol groups in the ring. For e.x., calix(4)arene has four phenol groups in the ring. The lining of benzene rings in the bowl shaped cavities of calixarenes allows them to acts as 'molecular baskets' for hydrophobic substrate like toluene, benzene and xylene.
The strength with which the substrate is bound depends on the complementarity of size. For e.x., toluene is firmly embedded in the bowl of a calix(4)arene but it is only loosely bound in the large cavity of calix(8)arene. It has been found that calix(7)arene will exhibit molecular recognition towards carbon cage fullerene molecules C60 and C70. The former with a soccer ball shape is bound tightly in the cavity, whereas the latter, with a rugby ball shape, is not. This provides a means of separating the two molecules which are generally formed in an intimate mixture.
Metal ions can serve as templates, that guide ligands into a particular arrangement. They, there by, act as organizing centers for synthesis of large supra-molecular assemblies from many component parts. In other words metal templation offers an effective approach to the self assembly of recognition sites.
Metal ions that form 4 coordinate square complexes are well suited to act as 90degree corners of square supra-molecular structures.
Metal ions with tetrahedral coordination geometries have been used as organizing centers for the multistep assembly of double helices (helicates). The two ligands twist around several metal ions in a double helical fashion. The two strands in these contain metal bound bipyridine units linked together. The efficiency of the self assembly process is the result of positive co-operativity, whereby the binding of one metal ion pre-organizes the ligands to facilitate the binding of the second. In other words, the assembly process gets easier as it progresses.
Similar strategies have been used to obtain molecular assemblies described as catenanes and rotaxanes. An assembly in which one ring is linked through another is called a catenane. A rotaxane is a linear molecule threaded through a cyclic molecule. Unthreading is prevented by subsequently adding bulky end caps.
One of the goals of supra-molecular chemistry is to build synthetic systems that carry out some of the functions of biochemical systems - trans membrane ion transport, enzyme -like catalysis, conducts for channeling electrons and chemical sensors with high sensitivity and selectivity.
Sunday, November 29, 2009
The Ant Story...
Hi friends here is the story of Ant, representing the today's work culture in an Organization. I found in the net thinking you too like it....
Every day, a small ANT arrives at work very early and start work very immediately. She produces a lot and she was happy.
The Chief, a LI ON was surprised to see that the Ant was working without supervision. He thought if the Ant can produce without supervision, wouldn't she produce even more if she had a supervisor!
So he recruited a COCKROACH who had an extensive experience as supervisor and who was famous for writing excellent reports. The Cockroach's first decision was to set up a clocking in attendance system. He also needed a secretary to help him write and type his reports.
He recruited a SPIDER, who managed the archives and monitored all phone calls.
The lion was delighted with Cockroach's report and asked him to produce graphs to describe production rates and analyze trends, so that he could use them for presentations at Board meetings.
So the Cockroach has to buy new computer and laser printer and recruited a FLY to manage the IT department.
The Ant, who had once been so productive and relaxed, hated this new plethora of paper work and meetings which used up most of her time.
The lion to the conclusion that it was high time to nominate a person in charge of department where the Ant worked.
The position was given to CICADA, whose first decision is to buy a carpet and an ergonomic chair for his office. The new person in charge, the Cicada, also needed a computer and personal assistant, who he brought from his previous department, to help him work and Budget control strategic optimization plan.
The department where the Ant works is the sad place, where nobody laughs anymore and everybody become upset.
It was at that time the Cicada convinced the Boss, the lion, of the absolute necessity to start a climatic study of the environment. Having reviewed the charges for running the Ant's department, the lion found out that the production was much less than before.
So he recruited OWL, a prestigious and renowned consultant to carry out an audit and suggest solutions. The owl spent three month in the department and came up with an enormous report, in several volumes, that concluded: "The department is overstaffed".
You are Right, the lion fires as per your GUESS !
The ANT, of course, because she "Showed lack of Motivation and had a Negative Attitude".
Saturday, November 28, 2009
Funny pics about Chemistry..
Hi friends,
These are the funny pictures about chemistry I saw in the internet and the pasted the few among them for you. I appreciate your comments for the improvement.
Friday, November 27, 2009
FMCG Industry in India.
Fast moving consumer goods (FMCG), also known as consumer packaged goods (CPG) are the products that have a quick turnover and relatively low cost. Consumers generally put less thought into the purchase of FMCG than they do for any other products.
The Indian FMCG industry witnessed significant changes through through 1990's. Many players had been facing severe problems on account of increased competition from small and regional players and from slow growth across its various product categories. As a result, most of the companies were forced to revamp their product, marketing, distribution and customer service strategies to strengthen their position in the market.
By the turn of 20th century, the face of Indian FMCG industry had changed significantly. With the liberalization and growth of economy, the Indian customer witnessed an increasing exposure to new domestic and foreign products through different media, such as television and the Internet. Apart from this, social changes such as an increase in the number of nuclear families and the growing number of working couples resulting in increased spending power also contributed to the increase in the Indian consumer's Personal consumption. The realization of the customer's growing awareness and the need to meet changing requirements and preferences on account of changing lifestyles required the FMCG producing companies to formulate customer-centric strategies. These changes have a positive impact, leading to the rapid growth in the FMCG industry. Increased availability of retail space, rapid urbanization and qualified manpower also boosted the growth of the organized retailing sector.
HUL led the way in revolutionizing the product, market, distribution and service formats of the FMCG industry by focusing on rural markets, direct distribution, creating new product, distribution and service formats. The FMCG sector also received a boost by the government led initiatives in the 2003 budget such as setting up of excise free zones in various parts of the country that witnessed firms moving away from outsourcing to manufacturing by investing in the zones.
Though the absolute profit made on FMCG products is relatively small, they generally sell in large numbers and so the cumulative profit on such products can be large. Unlike some industries, such as automobiles, computers and airlines FMCG doesn't suffer from mass layoffs ever time the economy starts to dip. A person may put off buying a car but he Will not put off having his dinner.
Unlike other economy sectors, FMCG share float in a steady manner irrespective of global market dip, because they generally satisfy rather fundamental, as opposed to luxurious needs. The FMCG sector which is growing at a rate of 9% is the fourth largest sector in the Indian economy and is a worth of Rs. 93000 crores. The main contributor, making up 32% of the sector, is the south Indian region. It is predicted that in the year 2010, the FMCG sector will be worth Rs.143000 crores. The sector being one of the biggest sectors of the Indian economy provides upto 4 million jobs.
The FMCG sector consists of the following categories:
Personal care - Oral care, Hair care, Wash (soaps), Cosmetics and Toiletries, Deodorants and perfumes, Paper products (Tissues, Diapers, Sanitary products) and Shoe care; the major players being Hindustan Uni-liver Limited, Godrej Soaps, Colgate, Marico, Dabur and Procter & Gamble.
Household Care - Fabric wash (laundry soaps and detergents), Household cleaners (Dish/utensil/floor/toilet cleaners), Air fresheners, Inseticides and Mosquito repallants, Metal polish and Furniture polish; the major players being Hinduatn Uni-liver Limited, Nirma and Ricket Colman.
Branded and Packaged Foods and Beverages - Health beverages, Soft drinks, Staples/Cereals, Bakery products (Biscuits, Breads, cakes), Snack foods, Chocolates, Ice-creams, Tea, Coffee, Processed fruits, Processed vegetables, Processed Meat, Branded flour, Bottled water, Branded rice, Branded sugar, Juices; the major players being Hindustan Uni-liver Limited, Nestle, Coca-Cola, Cadbury, Pepsi and Dabur.
Spirits and Tobacco - The major players being ITC, Godfrey, Philips and UB.
Source : http://www.economywatch.com/world-industries/fmcg.html
Thursday, November 26, 2009
Biochemical Importance of Nitric Oxide (NO)
Nitric Oxide has provided one of the biggest biological surprises. It has recently been shown to be an important messenger in many Vertebrate signal transduction processes. This free radical gas has been identified in the human brain and detected in exhaled breath.
NO is a vital and the first gaseous biological messenger to be identified. It diffuses freely across membranes, but has a short life less than a few seconds, because it is highly reactive. Hence, NO is well suited to serve as a transient signal molecule within cells and between adjacent cells.
Nitric Oxide is produced in the brain and serves as a neuro transmitter. It causes muscle cells to dilute and relax. It acts as a mediator of blood vessel relaxation and thus brings down blood pressure. This function is partly brought about by the activation of guanyl cyclase. Its formation is regarded as the main determinant of blood pressure in many species, including man.
Nitric oxide also participates in the transmission of nerve impulses, which is important in a range of activities, including gut contraction and food movement as well as penile erection.
NO is an effective killer of cells (Cytotoxic) or blocker of cell multiplication and growth (Cytostatic). It's known antibacterial activity possibly occurs via the generation of other radicals.
There are three variety of inhibitor of NO3 action and there may be of value in the treatment of certain clinical conditions arising from irregular production of NO.
NO is a vital and the first gaseous biological messenger to be identified. It diffuses freely across membranes, but has a short life less than a few seconds, because it is highly reactive. Hence, NO is well suited to serve as a transient signal molecule within cells and between adjacent cells.
Nitric Oxide is produced in the brain and serves as a neuro transmitter. It causes muscle cells to dilute and relax. It acts as a mediator of blood vessel relaxation and thus brings down blood pressure. This function is partly brought about by the activation of guanyl cyclase. Its formation is regarded as the main determinant of blood pressure in many species, including man.
Nitric oxide also participates in the transmission of nerve impulses, which is important in a range of activities, including gut contraction and food movement as well as penile erection.
NO is an effective killer of cells (Cytotoxic) or blocker of cell multiplication and growth (Cytostatic). It's known antibacterial activity possibly occurs via the generation of other radicals.
There are three variety of inhibitor of NO3 action and there may be of value in the treatment of certain clinical conditions arising from irregular production of NO.
Monday, November 23, 2009
Biochemical Importance of Calcium
Calcium metal is present in great abundance in the body, being mostly distributed in bones and teeth. A very small amount is present in the body fluids. Its concentration is more in the extracellular fluid than in the intracellular fluid.
Ca2+ ion is stored in the sarcoplasmic reticulum membrane on calcium binding proteins especially Calsequestrin. This protein has such a high affinity for Calcium that it binds about 43 Ca2+ ions per molecule. Ca2+ also binds to several other proteins such as troponin, parvalbumin, calmodulin, concavalin A and staphylococcal nuclease. Ca2+ plays an important role in several biological processes.
Calcium in bones and teeth:
About 99% of an adults calcium (~ 1.2 kg) is in bones and teeth. It is present as basic calcium phosphate (hydroxyapatite) reinforced by the protein collagen.
In teeth enamel the protein keratin is present instead of collagen. When there is deficiency of calcium in blood some of the calcium from bones dissolves to maintain the calcium level in blood.
Ca2+ in blood clotting:
Coagulation of blood occurs to prevent excess bleeding when tissues are damaged. The overall mechanism is complex and involves a cascade process many steps of which are dependent on Ca2+. Clot formation involves activation of certain proteins to form fibrin, the molecules of which are then cross-linked.
Ca2+ in muscle contraction:
Ca2+ plays an important role in the regulation of muscle contraction. Skeletal muscle contains an intricate network of membrane bound tubules and vesicles. This membrane system is called sarcoplasmic reticulum (SR) regulates the Ca2+ concentration surrounding the contractile fibers of the muscles. At rest Ca2+ is pumped into the SR so that the concentration of Ca2+ around the muscle fibers is very low. Excitation of the SR membrane by a nerve impulse leads to a sudden release of large amounts of Ca2+ which triggers muscle contraction. In other words, Ca2+ is the intermediary between nerve impulse and muscle contraction.
The major constituents of the muscle fibre are the proteins myosin and actin, plus the regulatory proteins troponin and tropomysin. Each muscle fibre is made up of some of 1000 fibrils. Myosin and actin are organized in the fibril in the form of two filaments, one thick and one thin. Muscle contraction and relaxation results from the sliding of one filaments over the other. The interaction of myosin and actin is inhibited by troponin and tropomysin in the absence of Ca2+. Nerve excitation triggers the release of Ca2+ by SR. The released calcium binds to troponin and causes conformational changes that are transmitted to actin through tropomysin. These conformational changes enables actin to interact with myosin resulting in muscle contraction and ATP hydrolysis which persists till Ca2+ is removed.
Ca2+ as a messenger:
A primary messenger is an extracellular agent which responds to an extracellular stimulus. The signal is transmitted via a secondary messenger> Ca2+ acts as a secondary messenger intracellularly because its concentration can change rapidly in response to external stimuli. Ca2+ ion binds to several proteins and in which it is catalytically most reactive. Thus Ca2+ initiates the activation or deactivation of a large number of proteins and enzymes.
The versatility of Ca2+ in inducing a variety of intracellular processes probably arises because there are many ways in which a polypeptide can fold around it. One of the Ca2+ binding proteins of note is calmodulin whose function is triggered by a change of Ca2+ ion concentration.
The calmodulins are small proteins with glutamate and aspartate residue which bind Ca2+ ions. The protein confirmation is changed on metal ion binding so that it can now reorganize, bind and activate an enzyme.
Saturday, November 21, 2009
MBA Dissertation Titles for finance, Marketing and HR.
Hi friends, proposed dissertation titles for MBA/BBM is listed below with specialization of Finance, marketing and HR...
Finance topics:
Marketing topics:
HR topics.
Finance topics:
- Working capital management in selective manufacturing companies.
- Cash management in selective Banks.
- Receivables management in selective companies.
- Inventory management in selective manufacturing companies.
- Inventory management in selective trading companies.
- Stock market analysis in selective listed companies in a particular stock exchange.
- A comparative stock market analysis in selective listed companies in selective stock exchanges.
- Online stock market analysis in selective listed companies.
- Derivative stock market analysis in a particular stock exchange.
- Financial performance analysis in selective companies.
- Financial performance analysis in selective Bank.
- Financial performance analysis in selective insurance companies.
- Portfolio plans analysis in selective companies.
- Portfolio plans analysis among investors.
- Mutual fund performance in selective MF companies.
- Risk analysis in mutual fund companies.
- Risk analysis in stock market in selective companies.
- Attitude of investors about various investment avenues.
- Risk analysis in insurance in selective companies.
- Attitude of investors on gold & silver investment in a selective area.
- Attitude of investors on the investment on precious metals, arts objects and antique.
- A study on workings of Reserve bank of India, Bangalore.
- Attitude of public towards the usage of Banking financial instruments in selective area.
- A study on working of selective bank branch.
- Attitude of investors towards post office savings, Deposits and Bond.
- Attitude of investors towards stock market and gild edged securities market.
- Attitude of public towards the usage of electronic purses(Debit & Credit card).
- Performance accounting in selective companies.
- Attitude of share brokers towards the present stock market scenario.
- An-in-depth analysis of financial statements of two or more manufacturing, retail or any sector.
- A study on MPBF - A study conducted of any two or more Banks.
- An empirical study on the impact of global crisis on Indian economy particularly with reference to one or more industry.
- A case study on a particular Banks or FIs.
- The study on trend in various types of Insurance of two pr more Insurance companies.
- An In-depth-analysis of state budget and its implications on industries and individuals.
- A study on performance/problems of small scale sector in Bangalore city.
- A study on credit card system of few Banks and its analysis, impact on society.
- A study on online Banking systems of a Bank.
- A study on SHG - self help group scheme promoted by Bank and its effectiveness.
- Comparative study on loans and advances in any two Banks or public sectors / private sector banks.
- A case study of Foreign exchange dealers / money changers.
- A study on pre / post crisis of real estate business in Bangalore city.
- A study on FMCG - comparison of selected consumer goods by different companies.
Marketing topics:
- Marketing of Banking services in selective banks.
- Marketing of life insurance services in selective insurance companies.
- Marketing of investment banking services in selective financial companies.
- Consumer trends in retail sectors / service sectors.
- Store operation management.
- Impact of retail layout and design on retail business.
- Retail selling skills.
- Promotional strategies in service apartments hotels.
- Scope for laundry business in Bangalore city.
- Effectiveness of product mix in electronic goods industry.
- Effect of sales promotion in electronic goods industry.
- Effect of store image in consumer behavior in electronic goods industry / retail sector.
- Branding products in online shops.
- The phenomenon of customer myopia.
- How to improve marketing effectiveness.
- Marketing customization.
- Marketing strategies and development.
- Assessing Risk in introducing high tech products.
- Channel management and channel partner.
- The role of logistics in wholesale storage.
- M - commerce.
- A study on change management and its impact on system administration.
- The role of e-commerce on profitability.
- Global economic crisis and its impact on marketing performance.
- Overseas marketing of Indian movie.
HR topics.
- Effectiveness of workers participation in ...................
- Trade unions and their role in IT sector.
- Code of conduct of MNC's.
- Corporate Governance : Applications and impact.
- Cross cultural, religious and racial issues in MNC's.
- An overall assessment on ethical programmes in private sector or public sector.
- Public sector vs private sector on effectiveness of ethical programmes.
- Ethical training programs.
- Training and development programmes.
- Determinants of executive compensation.
- Development of organizational commitment.
- Emerging alliances in health care.
- Employee attitudes, organizational climate and performance.
- Measures of work - family conflict.
- Project complexity, control and performance.
- Corporate sector and campus placement : A study with reference to Bangalore.
- Impact of health and wellness programmes on performance of employees.
- Global economic crisis and its impact on employees.
- Relationship between community and corporate sector (Community relations: Strategies and Action)
- Competency mapping.
- Executive talent acquisition.
- HR audit.
- Human resource information system.
- Social responsibilities of corporate sector with reference to IT and ITES sector.
Differnce between yellow and white gold ?
There is only one type of Gold since it is an element. Pure (or 24 carat) gold is yellow, but it is too soft for most uses. Nearly all the gold bought as jewellery, for example, is in the form of an alloy, though, and these alloys can have different colors.
Copper and Silver are commonly added to make the yellow gold used most of jewellery (9, 14, and 18 carat gold). To make an alloy that appears white (it is actually almost silver in appearance) nickel, zinc and palladium, are added. Nickel makes the gold looks like platinum, but many people are allergic to it. Palladium can be used to overcome this problem, but can be more expensive than gold making the final product was very expensive.
Many white gold rings are also rhodium plated to enhance their appearance. When they have been worn for some time, they can appear more yellow because the rhodium layer has been worn off.
Copper and Silver are commonly added to make the yellow gold used most of jewellery (9, 14, and 18 carat gold). To make an alloy that appears white (it is actually almost silver in appearance) nickel, zinc and palladium, are added. Nickel makes the gold looks like platinum, but many people are allergic to it. Palladium can be used to overcome this problem, but can be more expensive than gold making the final product was very expensive.
Many white gold rings are also rhodium plated to enhance their appearance. When they have been worn for some time, they can appear more yellow because the rhodium layer has been worn off.
What is Strategic Piggy backing ?
It is a new fund generating activity undertaken by the non-profit organization which is aimed at reducing the gap between expenses and revenue. The primary purpose is to subsidize the service program. It is gaining popularity in recent time. Educational institutes running commercial complexes hospitals running a meditation class and fitness program are typical example of piggy backing.
The non profit organization should have the following resources before adopting piggy backing strategy;
The non profit organization should have the following resources before adopting piggy backing strategy;
- some thing to sell
- critical mass of management talent
- trustee support
- entrepreneurial attitude.
HIstory of Indian Advertising agencies .....
The advertisement appeared during 18th century in the Hickely's Bengal Gazette, India's first newspaper, a weekly magazine. Advertising in the beginning was mainly for informative purposes rather than promotional reasons.
B.Dattaram & Co has to be the oldest agency in the advertising circuit in India establishing in 1905. In 1912 ITC, the giant tobacco company launched Gold Flake. In the 20's foreign advertising agencies entered the Indian market. Mergers and acquisition were seen to give rise to Ogilvy and Mather, Clarion etc. In 1929 J Walter Thompson (JWT) was established to service General motor Business.
Levers launched Dalda in 1939 and marketed it as an exclusive brand. A campaign format of advertising was particularly designed for the Indian market. Lux as we all know uses celebrity endorsements. In the same period HTA was the reincarnated name of JWT in India. It made Horlicks more relevant in India by introducing the Balanced nourishment concept.
The advertising group was thus formed in 1954. It motivated the advertising brotherhood with awards and brought the advertising circuit in a closer knit. from print to radio, advertising was exploring new avenues. 1967 witnessed first commercial on Vividh Bharathi.
Commercial television advertising began in 1976. But it was only in 1982 that Bombay Dying aired its first color TV commercial. Between 1985 and 86 a whooping 915 brands and services were visible in the Indian market.
Awards then came into being. Abbey is the award name christened by the advertising club. Cannes in France has become the biggest advertising award. Advertising on whole become the interesting career. Many students now professionalize in this field. These professionals are in demand as professional inputs to the industry only transcend it into the next level.
B.Dattaram & Co has to be the oldest agency in the advertising circuit in India establishing in 1905. In 1912 ITC, the giant tobacco company launched Gold Flake. In the 20's foreign advertising agencies entered the Indian market. Mergers and acquisition were seen to give rise to Ogilvy and Mather, Clarion etc. In 1929 J Walter Thompson (JWT) was established to service General motor Business.
Levers launched Dalda in 1939 and marketed it as an exclusive brand. A campaign format of advertising was particularly designed for the Indian market. Lux as we all know uses celebrity endorsements. In the same period HTA was the reincarnated name of JWT in India. It made Horlicks more relevant in India by introducing the Balanced nourishment concept.
The advertising group was thus formed in 1954. It motivated the advertising brotherhood with awards and brought the advertising circuit in a closer knit. from print to radio, advertising was exploring new avenues. 1967 witnessed first commercial on Vividh Bharathi.
Commercial television advertising began in 1976. But it was only in 1982 that Bombay Dying aired its first color TV commercial. Between 1985 and 86 a whooping 915 brands and services were visible in the Indian market.
Awards then came into being. Abbey is the award name christened by the advertising club. Cannes in France has become the biggest advertising award. Advertising on whole become the interesting career. Many students now professionalize in this field. These professionals are in demand as professional inputs to the industry only transcend it into the next level.
Explain Strategic Human resouce management (HRM)..
A strategy is a way of doing something. It usually includes the formulation of a goal and set of action plans for accomplishment for that goal. Strategic management may be understood as the process of formulating, implementing and evaluating business strategies to achieve organizational objectives.
"Strategic management is that set of managerial decisions and actions that determine the long term performance of a corporation. It includes environmental scanning, strategy formulation, strategy implementation and evaluation & control"
Corporate strategies and policies has great impact as human resource management. Strategy gives direction to the organization. A strategy when aligned with firms resources gives the firms a competitive advantage. Strategy HRM is process of optimum utilization of HR to achieve the organizational objectives through aligning HR goals with organizational strategies.
Strategies are formulated at three level:
Corporate Strategies are developed by top management of an organization. It may be growth strategy (diversification, expansion, mergers), stability strategy, retrenchment strategies, unit level and function strategy are developed consistence with corporate strategies.
Implementation of strategies requires various action like adding departments, changing prices and more importantly effective management of people.
Role of HR in Strategy formulation:
HR manager supplies competitive intelligence for strategy formulation. Strategy and weakness of HR has its influence on the viability of the company's strategic options.HR manager needs to play a more strategic role become a member of strategic management process. More firms are integrating HRM into strategic management realising the role played by the people in contributing to organizational effectiveness. Organizational and human resource plans and strategies are getting inextricably linked.
Role in strategy implementation:
HR has a great implementation of strategies. e.g., HDFC Strategic differentiate itself from competitors by providing buyers services at attractive rates, its implementation possible due to its competent workforce.
HR practices brings in competitiveness in strategy implementation, create a capacity for change and bring in a strategic unity. Implementation is facilitated by HRM by
a) encouraging proactive thinking rather than reactive behavior,
b)Explicit communication of goals,
c) Stimulation of clinical thinking,
d) Improving productivity and quality as an HR based strategy.
Role in Strategy management:
Through proper staffing in the organization, building core competences and competitive abilities and by effective structuring of the organization.
"Strategic management is that set of managerial decisions and actions that determine the long term performance of a corporation. It includes environmental scanning, strategy formulation, strategy implementation and evaluation & control"
Corporate strategies and policies has great impact as human resource management. Strategy gives direction to the organization. A strategy when aligned with firms resources gives the firms a competitive advantage. Strategy HRM is process of optimum utilization of HR to achieve the organizational objectives through aligning HR goals with organizational strategies.
Strategies are formulated at three level:
- Corporate level
- Business unit level and
- Functional level
Corporate Strategies are developed by top management of an organization. It may be growth strategy (diversification, expansion, mergers), stability strategy, retrenchment strategies, unit level and function strategy are developed consistence with corporate strategies.
Implementation of strategies requires various action like adding departments, changing prices and more importantly effective management of people.
Role of HR in Strategy formulation:
HR manager supplies competitive intelligence for strategy formulation. Strategy and weakness of HR has its influence on the viability of the company's strategic options.HR manager needs to play a more strategic role become a member of strategic management process. More firms are integrating HRM into strategic management realising the role played by the people in contributing to organizational effectiveness. Organizational and human resource plans and strategies are getting inextricably linked.
Role in strategy implementation:
HR has a great implementation of strategies. e.g., HDFC Strategic differentiate itself from competitors by providing buyers services at attractive rates, its implementation possible due to its competent workforce.
HR practices brings in competitiveness in strategy implementation, create a capacity for change and bring in a strategic unity. Implementation is facilitated by HRM by
a) encouraging proactive thinking rather than reactive behavior,
b)Explicit communication of goals,
c) Stimulation of clinical thinking,
d) Improving productivity and quality as an HR based strategy.
Role in Strategy management:
Through proper staffing in the organization, building core competences and competitive abilities and by effective structuring of the organization.
Salient features of Tanabe Sugano diagram.
The results of the evaluation of energies of various level in going from the weak field to strong cases are presented in graphical form in the Tanabe - Sugano diagram.
2) The Tanabe - Sugano diagrams are commonly used for the interpretation of the spectra including both weak & strong fields.
3) The actual coordination are Dq/B for the horizontal axis and E/B for the vertical axis.
4) The energy of the ground state is represented by the horizontal base line (ground state as the constant reference).
5) Configuration interaction is included as bending of lines for the excited states.
6) The energy of states with the spin multiplicity different from that of the ground state are also represented.
7) For d1-3 & d8-9 systems, the Tanabe - Sugano diagram sare qualitatively similar to Orgel diagram because the ground term doesn't change whatever the field. For d4-7 system there is a discontinuity in the Tanabe - Sugano diagram shown by the vertical line indicating a change from a high spin to low spin case. At this point the ground term also changes.
8) The quantities E/B and Dq/B are plotted because they enable one to convert the equation for the energy into a convenient form of plotting.
2) The Tanabe - Sugano diagrams are commonly used for the interpretation of the spectra including both weak & strong fields.
3) The actual coordination are Dq/B for the horizontal axis and E/B for the vertical axis.
4) The energy of the ground state is represented by the horizontal base line (ground state as the constant reference).
5) Configuration interaction is included as bending of lines for the excited states.
6) The energy of states with the spin multiplicity different from that of the ground state are also represented.
7) For d1-3 & d8-9 systems, the Tanabe - Sugano diagram sare qualitatively similar to Orgel diagram because the ground term doesn't change whatever the field. For d4-7 system there is a discontinuity in the Tanabe - Sugano diagram shown by the vertical line indicating a change from a high spin to low spin case. At this point the ground term also changes.
8) The quantities E/B and Dq/B are plotted because they enable one to convert the equation for the energy into a convenient form of plotting.
Charge - transfer transition
Charge transfer transition are associated transfer of an electron from one atom to another. Charge transfer band in the spectra of the complex ions are so named because the transition is responsible for them are between levels which correspond to different electron distribution among the metal and the ligand atoms in the ground and excited states.
A d-d transition involves redistribution of electrons among orbitals that are mainly localized on the metal atom. There are also electronic transitions in which electron moves from an essentially ligand-based orbital to an essentially metal based orbital or vice versa. When this happens charge is transferred from one part of the coordination sphere to another. The resulting spectroscopic features and the electronic transitions from which they arise are called, charge-transfer bands and charge transfer transitions.
In the process of transferring charge to or fro from the central ion that gains or losses electron so that charge transfer spectra have also been called redox spectra.
Type of charge - transfer spectra:
1) Intra ligand transition: The ligand such as SCN- as internal charge transfer transition usually located in the UV region of the spectrum. Corresponding transition occur in the coordinated ligand.
2) Ligand to metal (reduction) charge transfer transition (LMCT):
Transition may occur from molecular orbitals located primarily on the ligands, the metal ligand bonding sigma or pi molecular orbital located primarily on the metal atom. Such transition are termed ligand to metal charge transfer transitions.
3) Metal to ligand (oxidation) charge transfer transitions (MLCT):
Transition which involve electron being exited from non-bonding or anti-bonding orbitals located primarily on the metal atom to anti-bonding orbitals located primarily on the ligands are termed metal to ligand charge transfer transition.
The charge transfer bands generally occur in the UV region but occasionally are found tailing off N2 or even peaking in the visible region.
Charge transfer requires the energy levels on the 2 different atoms are fairly closed. Charge transfer always produce intense color since the restriction of the laposte & spin selection rules don't apply to transition between atom.
A d-d transition involves redistribution of electrons among orbitals that are mainly localized on the metal atom. There are also electronic transitions in which electron moves from an essentially ligand-based orbital to an essentially metal based orbital or vice versa. When this happens charge is transferred from one part of the coordination sphere to another. The resulting spectroscopic features and the electronic transitions from which they arise are called, charge-transfer bands and charge transfer transitions.
In the process of transferring charge to or fro from the central ion that gains or losses electron so that charge transfer spectra have also been called redox spectra.
Type of charge - transfer spectra:
1) Intra ligand transition: The ligand such as SCN- as internal charge transfer transition usually located in the UV region of the spectrum. Corresponding transition occur in the coordinated ligand.
2) Ligand to metal (reduction) charge transfer transition (LMCT):
Transition may occur from molecular orbitals located primarily on the ligands, the metal ligand bonding sigma or pi molecular orbital located primarily on the metal atom. Such transition are termed ligand to metal charge transfer transitions.
3) Metal to ligand (oxidation) charge transfer transitions (MLCT):
Transition which involve electron being exited from non-bonding or anti-bonding orbitals located primarily on the metal atom to anti-bonding orbitals located primarily on the ligands are termed metal to ligand charge transfer transition.
The charge transfer bands generally occur in the UV region but occasionally are found tailing off N2 or even peaking in the visible region.
Charge transfer requires the energy levels on the 2 different atoms are fairly closed. Charge transfer always produce intense color since the restriction of the laposte & spin selection rules don't apply to transition between atom.
Karl - Fischer Titrations.
The determination of water is one of the most common analytical determinations. Because of its widespread importance, many procedures for the determination involving physical and chemical methods have been developed. physical methods generally involve separation of the water by oven drying, absorption or azeotropic distillation. Many chemical reactions generally involving the hydrolysis of reactive agent, acetyl chloride and acetic anhydride have been suggested.
In 1935 an extremely, simply convenient and precise method was introduced by Karl Fischer. Water in a sample dispersed in an anhydrous solvent such as methanol is titrated directly with a reagent containing I2, SO2, pyridine and methanol. The method is reasonably specific for water and is commonly used for its determination.
Preparation of Karl - Fischer reagent:
The solution contain component in the ratio 1 mole I2 : 3 moles SO2 : 10 moles C5H5N : 129 moles CH3OH. The dilution with methanol should be such that 1cm3 of the resulting reagent reacts with 3 to 6 mg of water. However the composition may be altered in certain special cases.
Pyridine is required to combine with the acid products formed by the reaction. In addiction pyridine pyridine combines with I2 and SO2 (lewis acid base interaction) to reduce their vapor pressure and thus makes the reagent more stable. Methanol is a good solvent for the various products of the reaction end point. The chemicals used for the preparation of the KF reagent should not contain more than 0.1% water.
For preparing the reagent a known weight of iodine is taken in a dry glass stoppered bottle and required amount of anhydrous pyridine is added. The mixture is stirred till all iodine is dissolved. Required amount of anhydrous methanol is then added. The resulting stock solution is stable and may be kept almost indefinitely. Several days before the reagent is required. The stock solution is cooled in an ice bath, and liquid SO2 cooled in a solid CO2 bath is carefully added to the chilled stock solution. The mixture stoppered and allowed to return to room temperature. The reagent is kept for several days before using. Low temperature are to be maintained since the addition of SO2 to the stock solution is highly exothermic. Commercially available KF reagent generally consists of two stock solutions. One of I2 in methanol and the other SO2 in pyridine. These solutions are mixed several days before use.
Stability of the Reagent:
Freshly prepared KF reagent shows a marked decrease in strength within the first 2-3 days followed by a more gradual decrease with time. After the first week the strength decreases about 1% per day. The freshly prepared solution should be allowed, therefore to stand at least a week before being standardized. It should also be re standardized periodically, at least once each day of its use.
It has been observed that freshly prepared reagent generally has about 80% of its theoretical strength which decreases to about 40%after 3 months. Part of initial loss in strength comes from the moisture content of chemical, but part is most likely caused by side reactions leading to reduction of iodine to iodide. The rate of decrease in strength depends on how well the reagent is protected from moisture in air. Temperature doesn't markedly influence the decomposition of the reagent, but is slightly quickly. On the other hand the reagent prepared without SO2 is practically completely stable.
Studies have been made to substitute other nitrogen bases for pyridine (e.g., aniline, dimethylaniline, etc) and other inert solvent, for methanol (benzene, dioxan, ethanol, etc) in the KF reagent. However methanol and pyridine were found most suitable for various reasons.
The Titration method:
The Kf reagent is a very active desiccant. The apparatus used to store and dispense the reagent, and the titration flask assembly must be designed to protect the reagent from the moisture in air. The reagent solution can be used conveniently in all-glass automatic burettes having the solution reservoir and burette in an integral unit which can be protected with drying tubes.
The solution to be titrated should be protected from exposure to moist air. Very often the titration flask is attached to the burette by ground glass joint (or special plastic stoppers or sheets ) magnetic stirrer is used to mix the contents of the flask during titration.
The end point can be detected visually. The KF reagent has the dark brown color of iodine, which is changed to chromate yellow color by reduction with water. At the end point the color change from yellow to reddish brown of unused iodine is sharp and reproducible. However, visual end point is not useful for colored solution.
The electrometric method of end point detection can also be used. The "dead-stop" method is commonly used. A potential of 10-25mv is impressed between two platinum wire electrodes immersed in the titration solution. When iodide only is present in solution (i.e., before the end point ) the system is polarized and no current flows. When free iodine present at the end point there is an equilibrium between iodide and iodine and the system becomes polarized and galvanometer, register a flow of current in the circuit.
For a back titration, current flows through a galvanometer when the solution contains excess KF reagent (i.e., before the end point when iodide & iodine are in equilibrium) and drops to zero when the equivalence point is reached (i.e., when only iodide is present in solution)
Standardization of KF Reagent:
Because of the gradual decomposition of KF reagent, it must be standardized on each day of use. This is accomplished readily by titrating a known quantity of water with the reagent. several methods have been suggested for obtaining standard samples of water. These include pure water, standard solution of water in methanol and stable crystalline hydrates. The strength of the Kf reagent is normally expressed as water equivalent of KF reagent i.e., mg of water per cm3 of KF reagent.
In 1935 an extremely, simply convenient and precise method was introduced by Karl Fischer. Water in a sample dispersed in an anhydrous solvent such as methanol is titrated directly with a reagent containing I2, SO2, pyridine and methanol. The method is reasonably specific for water and is commonly used for its determination.
Preparation of Karl - Fischer reagent:
The solution contain component in the ratio 1 mole I2 : 3 moles SO2 : 10 moles C5H5N : 129 moles CH3OH. The dilution with methanol should be such that 1cm3 of the resulting reagent reacts with 3 to 6 mg of water. However the composition may be altered in certain special cases.
Pyridine is required to combine with the acid products formed by the reaction. In addiction pyridine pyridine combines with I2 and SO2 (lewis acid base interaction) to reduce their vapor pressure and thus makes the reagent more stable. Methanol is a good solvent for the various products of the reaction end point. The chemicals used for the preparation of the KF reagent should not contain more than 0.1% water.
For preparing the reagent a known weight of iodine is taken in a dry glass stoppered bottle and required amount of anhydrous pyridine is added. The mixture is stirred till all iodine is dissolved. Required amount of anhydrous methanol is then added. The resulting stock solution is stable and may be kept almost indefinitely. Several days before the reagent is required. The stock solution is cooled in an ice bath, and liquid SO2 cooled in a solid CO2 bath is carefully added to the chilled stock solution. The mixture stoppered and allowed to return to room temperature. The reagent is kept for several days before using. Low temperature are to be maintained since the addition of SO2 to the stock solution is highly exothermic. Commercially available KF reagent generally consists of two stock solutions. One of I2 in methanol and the other SO2 in pyridine. These solutions are mixed several days before use.
Stability of the Reagent:
Freshly prepared KF reagent shows a marked decrease in strength within the first 2-3 days followed by a more gradual decrease with time. After the first week the strength decreases about 1% per day. The freshly prepared solution should be allowed, therefore to stand at least a week before being standardized. It should also be re standardized periodically, at least once each day of its use.
It has been observed that freshly prepared reagent generally has about 80% of its theoretical strength which decreases to about 40%after 3 months. Part of initial loss in strength comes from the moisture content of chemical, but part is most likely caused by side reactions leading to reduction of iodine to iodide. The rate of decrease in strength depends on how well the reagent is protected from moisture in air. Temperature doesn't markedly influence the decomposition of the reagent, but is slightly quickly. On the other hand the reagent prepared without SO2 is practically completely stable.
Studies have been made to substitute other nitrogen bases for pyridine (e.g., aniline, dimethylaniline, etc) and other inert solvent, for methanol (benzene, dioxan, ethanol, etc) in the KF reagent. However methanol and pyridine were found most suitable for various reasons.
The Titration method:
The Kf reagent is a very active desiccant. The apparatus used to store and dispense the reagent, and the titration flask assembly must be designed to protect the reagent from the moisture in air. The reagent solution can be used conveniently in all-glass automatic burettes having the solution reservoir and burette in an integral unit which can be protected with drying tubes.
The solution to be titrated should be protected from exposure to moist air. Very often the titration flask is attached to the burette by ground glass joint (or special plastic stoppers or sheets ) magnetic stirrer is used to mix the contents of the flask during titration.
The end point can be detected visually. The KF reagent has the dark brown color of iodine, which is changed to chromate yellow color by reduction with water. At the end point the color change from yellow to reddish brown of unused iodine is sharp and reproducible. However, visual end point is not useful for colored solution.
The electrometric method of end point detection can also be used. The "dead-stop" method is commonly used. A potential of 10-25mv is impressed between two platinum wire electrodes immersed in the titration solution. When iodide only is present in solution (i.e., before the end point ) the system is polarized and no current flows. When free iodine present at the end point there is an equilibrium between iodide and iodine and the system becomes polarized and galvanometer, register a flow of current in the circuit.
For a back titration, current flows through a galvanometer when the solution contains excess KF reagent (i.e., before the end point when iodide & iodine are in equilibrium) and drops to zero when the equivalence point is reached (i.e., when only iodide is present in solution)
Standardization of KF Reagent:
Because of the gradual decomposition of KF reagent, it must be standardized on each day of use. This is accomplished readily by titrating a known quantity of water with the reagent. several methods have been suggested for obtaining standard samples of water. These include pure water, standard solution of water in methanol and stable crystalline hydrates. The strength of the Kf reagent is normally expressed as water equivalent of KF reagent i.e., mg of water per cm3 of KF reagent.
AGOSTIC BOND
Metal hydrogen interactions with C-H groups
There is compelling evidence that transition metal complexes may bind to C-H groups on ligands to give M......H-C "hydrogen bonding" type interactions. The term "agostic"has been coined by M.L.H Green for such hydrogen atoms (In Greek agostic means "to clasp" )
Two main types of M........H-C interactions referred to as open or closed are known. Complexes which would otherwise be coordinatively unsaturated can be stabilized by the interaction of C-H bonding pair of electrons with the metal.
1) Open Interaction:
The interaction appears to arise between an electron deficient metal center and a C-H bond of an alkyl group or a phenyl group. Examples of ortho hydrogen atoms on phenyl rings of a phosphene being near to a metal and occupying a coordination site have long been known. An early examples was RuCl2(PPh3)2 (16 electrons) where interaction with C-H would tend to move the complex to an 18 electron configuration.
Another exemple of this agostic is in the structure of W(CO)3(PCy3)2(Cy-cyclo-hexyl) where one ligand distort to permit close approach of the C-H bond to the tungsten and thus increases the electron count from 16 to 18.
2) Closed M........H-C Interactions:
This class differs from the previous one in that it involves allylic or cycloalkenyl systems where the metal atom attempts to achieve an 18 electron configuration by M.......H-C 2e-3C bond formation.
A vacant metal orbital is the necessary but not the sufficient condition for agostic interaction to occur. Many compounds are known where structure and spectra give no evidence of agostic interactions even though there is an empty metal orbital.
There is compelling evidence that transition metal complexes may bind to C-H groups on ligands to give M......H-C "hydrogen bonding" type interactions. The term "agostic"has been coined by M.L.H Green for such hydrogen atoms (In Greek agostic means "to clasp" )
Two main types of M........H-C interactions referred to as open or closed are known. Complexes which would otherwise be coordinatively unsaturated can be stabilized by the interaction of C-H bonding pair of electrons with the metal.
1) Open Interaction:
The interaction appears to arise between an electron deficient metal center and a C-H bond of an alkyl group or a phenyl group. Examples of ortho hydrogen atoms on phenyl rings of a phosphene being near to a metal and occupying a coordination site have long been known. An early examples was RuCl2(PPh3)2 (16 electrons) where interaction with C-H would tend to move the complex to an 18 electron configuration.
Another exemple of this agostic is in the structure of W(CO)3(PCy3)2(Cy-cyclo-hexyl) where one ligand distort to permit close approach of the C-H bond to the tungsten and thus increases the electron count from 16 to 18.
2) Closed M........H-C Interactions:
This class differs from the previous one in that it involves allylic or cycloalkenyl systems where the metal atom attempts to achieve an 18 electron configuration by M.......H-C 2e-3C bond formation.
A vacant metal orbital is the necessary but not the sufficient condition for agostic interaction to occur. Many compounds are known where structure and spectra give no evidence of agostic interactions even though there is an empty metal orbital.
Ion - Chromatography..
Ion Chromatography is a relatively new technique which employs a novel manner some well-established principles of ion exchange of allows electrical conductance to be used for detection and quantitative determination of ions in solution after their separation.
Since electrical conductance is a property common to all ionic species in the solution, a conductivity detector clearly has the potential of being a universal monitor for all ionic species.
In Ionic-exchange chromatography there is a problem of electrical back ground i.e., the high conductance of HCl in the effluent effectively "swamps" the lower conductance due to Na+ & K+in their separation and determination. So it prevents their measurement by electrical conductance.
In Ion-Chromatography this problem of electrical background is overcome by means of effluent suppression. This in the above example of Na+ - K+ analysis, if the effluent from separating column is passed through a strong base anion exchange resin in hydroxide form (suppressor column) following process occur.
a) HCl + OH-(resin) gives Cl-(resin) + H2O
b) NaCl/KCl + OH- (resin) gives NaOH/KOH +Cl- (resin)
Thus, the sample cations are presented to the conductivity detector not in highly conducting background, but in a very conducting background of de-ionized water.
Ion-Chromatography permits determination of both inorganic and organic species (ionic) often in concentrations of 50ppb or less. Since analysis time is short (less than 20 min) sample volume may be less than 1ml. Ion-chromatography is a fast and economical technique found its applications in different areas of chemical analysis particularly for quantitative determination of anions.
Ion - Chromatography flow scheme:
Separator Column: In this the specific capacity of the column is kept small using resins of low capacity. These resins are stable over a wide pH range.
Suppressor column: Where the electrical conductance is used for sample ion detection in effluent from the column, as eluant background of low conductivity is required. Function of suppressor column is to convert eluant ions into species giving low or zero conductance, e.x., NaHCO3 used as eluant for anion analysis. This is converted into a dilute carbonic acid background using strong strong acid suppressor resin.
Detector used in Ion-Chromatography:
1) Detectors employing electrochemical principles:
i) Conductometric detectors: Optimum mode of detection for strong acid anions (pKa <> 7 ). This has interchangeable Ag & Platinum working electrodes and may be used alone or simultaneously with conductivity detector.
2) Detectors based on optical absorption and emission techniques.
a) Spectrophotometric detectors
Based on the absorbance of monochromatic light by the column effluent according to Beer-Lamberts law. As most organic species have significant absorption in the UV region of the spectrum these detectors have wide applications.
b) Fluorescence detectors:
The ionic species are converted into fluorescent compounds by post column derivatisation and then detected.
Ion-Chromatography has been successfully applied to quantitative analysis of ions in industrial and environmental samples. The technique is valuable for micro-elemental analysis.
Since electrical conductance is a property common to all ionic species in the solution, a conductivity detector clearly has the potential of being a universal monitor for all ionic species.
In Ionic-exchange chromatography there is a problem of electrical back ground i.e., the high conductance of HCl in the effluent effectively "swamps" the lower conductance due to Na+ & K+in their separation and determination. So it prevents their measurement by electrical conductance.
In Ion-Chromatography this problem of electrical background is overcome by means of effluent suppression. This in the above example of Na+ - K+ analysis, if the effluent from separating column is passed through a strong base anion exchange resin in hydroxide form (suppressor column) following process occur.
a) HCl + OH-(resin) gives Cl-(resin) + H2O
b) NaCl/KCl + OH- (resin) gives NaOH/KOH +Cl- (resin)
Thus, the sample cations are presented to the conductivity detector not in highly conducting background, but in a very conducting background of de-ionized water.
Ion-Chromatography permits determination of both inorganic and organic species (ionic) often in concentrations of 50ppb or less. Since analysis time is short (less than 20 min) sample volume may be less than 1ml. Ion-chromatography is a fast and economical technique found its applications in different areas of chemical analysis particularly for quantitative determination of anions.
Ion - Chromatography flow scheme:
Separator Column: In this the specific capacity of the column is kept small using resins of low capacity. These resins are stable over a wide pH range.
Suppressor column: Where the electrical conductance is used for sample ion detection in effluent from the column, as eluant background of low conductivity is required. Function of suppressor column is to convert eluant ions into species giving low or zero conductance, e.x., NaHCO3 used as eluant for anion analysis. This is converted into a dilute carbonic acid background using strong strong acid suppressor resin.
Detector used in Ion-Chromatography:
1) Detectors employing electrochemical principles:
i) Conductometric detectors: Optimum mode of detection for strong acid anions (pKa <> 7 ). This has interchangeable Ag & Platinum working electrodes and may be used alone or simultaneously with conductivity detector.
2) Detectors based on optical absorption and emission techniques.
a) Spectrophotometric detectors
Based on the absorbance of monochromatic light by the column effluent according to Beer-Lamberts law. As most organic species have significant absorption in the UV region of the spectrum these detectors have wide applications.
b) Fluorescence detectors:
The ionic species are converted into fluorescent compounds by post column derivatisation and then detected.
Ion-Chromatography has been successfully applied to quantitative analysis of ions in industrial and environmental samples. The technique is valuable for micro-elemental analysis.
Applications of Genetic Engineering.
Genetic manipulation in a controlled and predetermined way is called Genetic Engineering, with the advent of Gene cloning protocols it is possible to transfer genes from one organisms to another organism (Prokaryotes to eukaryotes and vice versa).
Genetic Engineering, finds lot of potential applications in various fiedls like agriculture, medicine industry and environment. The applications include the production of Transgenic plants, animals and genetically engineered microorganisms (GEMs). Various products include hormones, (like insulin, growth hormone), enzymes, antibodies, blood clotting factors, interferon, vaccines and molecular diagnostics. In addition to these plants with herbicide, insecticide and pest resistance have been developed by means of gene cloning.
rDNA products are safer and economical and can be produced in large quantities. For e.g., an E.coli culture of about 2 liters can produce growth hormone i.e., equivalent to growth hormones derived from 100 sheep brains.
HUMAN INSULIN:
Insulin is produced by the pancreas (Islets of Langerhans / beta - cells). This is used in the treatment of Diabetes Mellitus. Previously insulin was obtained from animal sources like Bovine insulin, Procin insulin, Murine insulin. These insulin are not similar in their structures with that of human insulin. So generally they lead to the allergic reactions. Now a days human insulin is produced by r-DNA technology which is 100% similar and effective and economical .
c-DNA molecules were synthesized from the m-RNA molecules of both A & B chains of insulin and cloned into the plasmid vector DNA molecules, introduced into the E-coli cells separately and extracted both polypeptide chains, joined in vitro to form active insulin molecules. Human insulin was the first therapeutic produced by the gene cloning technology.
HUMAN GROWTH HORMONE (HGH):
Also known as Somatotropin, secreted by the anterior lobe of pitvitary gland, promotes growth and consists of 191 amino acids residues. Deficiency causes pituitary dwarfism.
Previously this hormone is extracted from pituitary glands an dis not sufficient to meet the increasing demand and now a days, it is produced by means of gene cloning.
Double stranded c-DNA were produced from m-RNA precursor of HGH and incorporated into bacterial cells, where it is expressed in non-precursor from. Bacteria were unable to convert peptide into biologically active form.
The synthetic DNA and c-DNA are ligated to yield a new fragment which contains the complete coding sequence of HGH. It is ligated to Lac promoter and operator and allowed to transform in E-coli and where it is expressed to produce HGH & subsequently purified.
RABIES (VIRUS) VACCINE:
Rabies virus cause a deadly disease rabies in human due to mad dog bite, discovered by Louis Pastuer. The conventional anti virus is difficult to obtain and the production procedure is very tedious one. Research attempts are being made to develop a recombinant rabies vaccine by using E-coli as host.
Attempts are made to isolate m-RNA coding for the viral protein from the rabies virus infected cells and the gene coding for the viral glycoprotein coat been successfully cloned in E-coli cells.
The wister institue of philadelphia (USA) has developed a new genetically engineered vaccine virus by inserting a small fragment of foreign DNA. This virus could synthesize anti rabies antigen and activates immune system against infection in laboratory animals when administered orally.
Genetic Engineering, finds lot of potential applications in various fiedls like agriculture, medicine industry and environment. The applications include the production of Transgenic plants, animals and genetically engineered microorganisms (GEMs). Various products include hormones, (like insulin, growth hormone), enzymes, antibodies, blood clotting factors, interferon, vaccines and molecular diagnostics. In addition to these plants with herbicide, insecticide and pest resistance have been developed by means of gene cloning.
rDNA products are safer and economical and can be produced in large quantities. For e.g., an E.coli culture of about 2 liters can produce growth hormone i.e., equivalent to growth hormones derived from 100 sheep brains.
HUMAN INSULIN:
Insulin is produced by the pancreas (Islets of Langerhans / beta - cells). This is used in the treatment of Diabetes Mellitus. Previously insulin was obtained from animal sources like Bovine insulin, Procin insulin, Murine insulin. These insulin are not similar in their structures with that of human insulin. So generally they lead to the allergic reactions. Now a days human insulin is produced by r-DNA technology which is 100% similar and effective and economical .
c-DNA molecules were synthesized from the m-RNA molecules of both A & B chains of insulin and cloned into the plasmid vector DNA molecules, introduced into the E-coli cells separately and extracted both polypeptide chains, joined in vitro to form active insulin molecules. Human insulin was the first therapeutic produced by the gene cloning technology.
HUMAN GROWTH HORMONE (HGH):
Also known as Somatotropin, secreted by the anterior lobe of pitvitary gland, promotes growth and consists of 191 amino acids residues. Deficiency causes pituitary dwarfism.
Previously this hormone is extracted from pituitary glands an dis not sufficient to meet the increasing demand and now a days, it is produced by means of gene cloning.
Double stranded c-DNA were produced from m-RNA precursor of HGH and incorporated into bacterial cells, where it is expressed in non-precursor from. Bacteria were unable to convert peptide into biologically active form.
The synthetic DNA and c-DNA are ligated to yield a new fragment which contains the complete coding sequence of HGH. It is ligated to Lac promoter and operator and allowed to transform in E-coli and where it is expressed to produce HGH & subsequently purified.
RABIES (VIRUS) VACCINE:
Rabies virus cause a deadly disease rabies in human due to mad dog bite, discovered by Louis Pastuer. The conventional anti virus is difficult to obtain and the production procedure is very tedious one. Research attempts are being made to develop a recombinant rabies vaccine by using E-coli as host.
Attempts are made to isolate m-RNA coding for the viral protein from the rabies virus infected cells and the gene coding for the viral glycoprotein coat been successfully cloned in E-coli cells.
The wister institue of philadelphia (USA) has developed a new genetically engineered vaccine virus by inserting a small fragment of foreign DNA. This virus could synthesize anti rabies antigen and activates immune system against infection in laboratory animals when administered orally.
SERVQUAL..
The popular tool used for measuring quality in services is called 'Servqual' and is based on the service quality difference diagram. Servqual was developed by Parasuraman and others and is basically a multiple-item scale used for measuring the five criteria of service quality, i.e, reliability, willingness, empathy, assurance, assurance and tangibles. Thus, it measures consumer perceptions of service quality. Servqual can also be used in marketing studies for comparing service firms to identify the criteria of superior service quality and also those areas in which they lack as compared to competitors and improvement can subsequently result. It has been found that the quality of service of a service has two distinct components:
The technical service quality: The outcome component of the service delivery process and functional service quality: The service encounter component during which the customer and server interact.
There are five main criteria which have been identified by carrying out market research on the basis of which service quality is determined.
1) Reliability: It implies the capacity of the service firm to deliver the promised service depending and accurately. This means that the same service is performed every time, in the same way and without mistakes. For e.g., Receiving the newspaper or milk at approximately the same time each day is quite important for people.
2) Willingness: It refers to how willing employees are to help customers and provide prompt service. Customers do not like to wait unnecessary and if this happens, it reflects badly on the quality of service.
3) Assurance: It means the knowledge that the providers possess which enables them to perform the service competently. It also includes attitudes like courtesy, politeness and respect for customers. This conveys trust and confidence and generally convinces the customer that the server holds the customer's best interest on a high pedestal.
4) Empathy: It means the power of understanding the customers feelings and need which allows the server to care for him and provide personal attention to him. With this, a customer feels that he can approach the server with confidence and has a feeling of security.
5) Tangibles: It includes the overall appearance of the surroundings, equipment, information material (brochures, handouts, menus etc) and personnel. This can act as visible evidence of the care and attention to details shown by the service firm.
The technical service quality: The outcome component of the service delivery process and functional service quality: The service encounter component during which the customer and server interact.
There are five main criteria which have been identified by carrying out market research on the basis of which service quality is determined.
1) Reliability: It implies the capacity of the service firm to deliver the promised service depending and accurately. This means that the same service is performed every time, in the same way and without mistakes. For e.g., Receiving the newspaper or milk at approximately the same time each day is quite important for people.
2) Willingness: It refers to how willing employees are to help customers and provide prompt service. Customers do not like to wait unnecessary and if this happens, it reflects badly on the quality of service.
3) Assurance: It means the knowledge that the providers possess which enables them to perform the service competently. It also includes attitudes like courtesy, politeness and respect for customers. This conveys trust and confidence and generally convinces the customer that the server holds the customer's best interest on a high pedestal.
4) Empathy: It means the power of understanding the customers feelings and need which allows the server to care for him and provide personal attention to him. With this, a customer feels that he can approach the server with confidence and has a feeling of security.
5) Tangibles: It includes the overall appearance of the surroundings, equipment, information material (brochures, handouts, menus etc) and personnel. This can act as visible evidence of the care and attention to details shown by the service firm.
Real Time Gross Settlement (RTGS)
RTGS system is a funds transfer mechanism where transfer of money takes place from one bank to another on a 'real time' and on a 'gross' basis. This is the fastest possible money transfer system through the banking channel. Settlement in 'real time' means payment transaction is not subjected to any waiting period. The transactions are settled as soon as they are processed. 'Gross settlement' means the transaction is settled on one to one basis without bunching with any other transaction.
The RTGS system is primarily for large value transactions. The minimum amount remitted through RTGS is Rs 1 lakh. There is no upper ceiling for RTGS transactions. No minimum or maximum stipulation has been fixed for electronic fund transfer system and National electronic funds transfer system.
Under normal circumstances the beneficiary branches are expected to receive the funds in real time as soon as funds are transferred by the remitting bank. The beneficiary bank has to credit the beneficiary's account within two hours of receiving the fund transfer message.
RTGS service for customer's transaction is available from 9:00 hours to 16:30 hours on week days and from 9:00 hours to 12:00 noon on Saturdays for settlement at the RBI end. However, the timings that the banks follow may vary depending on the customer timings of the bank branches. Bank will levy processing charges for offering various products.
The RTGS system is primarily for large value transactions. The minimum amount remitted through RTGS is Rs 1 lakh. There is no upper ceiling for RTGS transactions. No minimum or maximum stipulation has been fixed for electronic fund transfer system and National electronic funds transfer system.
Under normal circumstances the beneficiary branches are expected to receive the funds in real time as soon as funds are transferred by the remitting bank. The beneficiary bank has to credit the beneficiary's account within two hours of receiving the fund transfer message.
RTGS service for customer's transaction is available from 9:00 hours to 16:30 hours on week days and from 9:00 hours to 12:00 noon on Saturdays for settlement at the RBI end. However, the timings that the banks follow may vary depending on the customer timings of the bank branches. Bank will levy processing charges for offering various products.
Franck Condon Principle..
Statement states that: "An electronic transition takes place so rapidly that a vibrating molecule doesn't change its internuclear distance appreciably during the transaction".
a) Upper electronic state has the same equilibrium internuclear distance as the lower. Franck condon principle suggest that the transition occur vertically on this diagram since internuclear distance doesn't change and so if we consider the molecule to be initially in the ground state both electronically and vibrationally then the most probable transition is that indicated by the vertical line. Based on these line of V"=0 progression will be (0,0) line.
b) Upper state inter nuclear distance is little greater than that in the lower state. There is a small chance that the atom being near the extremities of the vibrational motion. Hence there is some chance of the transition starting from V"=0 state and finishing in V'=1,2,........ state in this case (1,0) line is the most intense line.
c) The upper state distance is considerably larger so in this case only few lines are seen in the spectrum and there is a continuum of the point at which continuum begins corresponds to the dissociation of the molecule.
a) Upper electronic state has the same equilibrium internuclear distance as the lower. Franck condon principle suggest that the transition occur vertically on this diagram since internuclear distance doesn't change and so if we consider the molecule to be initially in the ground state both electronically and vibrationally then the most probable transition is that indicated by the vertical line. Based on these line of V"=0 progression will be (0,0) line.
b) Upper state inter nuclear distance is little greater than that in the lower state. There is a small chance that the atom being near the extremities of the vibrational motion. Hence there is some chance of the transition starting from V"=0 state and finishing in V'=1,2,........ state in this case (1,0) line is the most intense line.
c) The upper state distance is considerably larger so in this case only few lines are seen in the spectrum and there is a continuum of the point at which continuum begins corresponds to the dissociation of the molecule.
Use of Tetramethylsilane in NMR.
Tetramethylsilane is the simplest Tetraorganosilane, with structure of Terahedral.
- Single sharp peak is obtained during the experiment.
- Dissolve in organic compounds.
- TMS is inert with the sample.
- Its a volatile compound with 27 degree and hence can be recovered.
- Since the protons are highly shielded the peaks like clear off, the peaks of other organic compound there is no overlap of the peak.
Broadband Oscillator for proton decoupled 13C spectra
A very wide range of frequencies may be irradiated by using a broadband oscillator.
Proton decoupling is accomplished in the process of determining a 13C NMR spectrum by simultaneously irradiating all of the proton in the molecule with a broad spectrum of frequencies in the proper range.
Most modern NMR spectrometer provide a second tunable radio frequency generator, the decoupler for this purpose.
Irradiation causes the protons to become saturated and they undergo rapid upward and downward transitions, among all their spin states. These rapid transition decompose any spin-spin interaction between the hydrogen and 13C nuclei being observed. In effect, all spin interactions are averaged to zero by the rapid changes. The carbon nucleus senses only one average spin state for the attached hydrogen rather than two or more distinct spin states.
Proton decoupling is accomplished in the process of determining a 13C NMR spectrum by simultaneously irradiating all of the proton in the molecule with a broad spectrum of frequencies in the proper range.
Most modern NMR spectrometer provide a second tunable radio frequency generator, the decoupler for this purpose.
Irradiation causes the protons to become saturated and they undergo rapid upward and downward transitions, among all their spin states. These rapid transition decompose any spin-spin interaction between the hydrogen and 13C nuclei being observed. In effect, all spin interactions are averaged to zero by the rapid changes. The carbon nucleus senses only one average spin state for the attached hydrogen rather than two or more distinct spin states.
Nuclear Overhauser Enhancement (NOE)..
When we obtain a proton decoupled 13C spectrum the intensities of many of the carbon resonances increases significantly above those observed in a proton-coupled experiment carbon atoms with hydrogen atom directly attached are enhanced the most and the enhancement increases (but not always linearly) as more hydrogen are attached. This effect is known as the nuclear overhauser enhancement.
The nuclear overhauser effect is general, showing up when one of the two different types of atoms is irradiated while the NMR spectrum of the other type is determined.
The effect can be either positive or negative depending on which atom type are involved. In the case of carbon-13 interacting with hydrogen-1, the effect is positive irradiating the hydrogen increases the intensities of the carbon signals. The maximum enhancement that can be observed is given by the relationship,
NOE max = 1/2(r irr/r obs)
For a proton decoupled 13C spectrum
NOE max = 1/2 (2.675/0.6728) = 1.988
This value is a theoretical maximum and most actual cases exhibit less than ideal enhancement.
The nuclear overhauser effect is general, showing up when one of the two different types of atoms is irradiated while the NMR spectrum of the other type is determined.
The effect can be either positive or negative depending on which atom type are involved. In the case of carbon-13 interacting with hydrogen-1, the effect is positive irradiating the hydrogen increases the intensities of the carbon signals. The maximum enhancement that can be observed is given by the relationship,
NOE max = 1/2(r irr/r obs)
For a proton decoupled 13C spectrum
NOE max = 1/2 (2.675/0.6728) = 1.988
This value is a theoretical maximum and most actual cases exhibit less than ideal enhancement.
Off Resonance decoupling
This technique can be provide multiplets information (about the attached protons) while keeping the spectrum relatively simple in appearance.
In an off resonance decoupled 13C spectrum the coupling between each carbon atom and each hydrogen attached directly to it is observed. However the apparent magnitude of the coupling constant is reduced, the overlap of the resulting multiplets is a less frequent problem.
The off resonance decoupled spectrum retains the couplings between the carbon atom and directly attached proton but effectively remove the couplings between the carbon and more remote protons.
In this technique, the frequency of a second radio frequency transmitter (the decoupler) is set either up field or down field from the usual sweep width of a normal proton spectrum (off resonance). In contrast, in a true decoupling experiment the frequency of the decoupler is set 10-1 coincide exactly with the range of proton resonances.
Furthermore in off resonance decoupling, the power of the decoupling oscillator is held low to avoid complete decoupling.
In an off resonance decoupled 13C spectrum the coupling between each carbon atom and each hydrogen attached directly to it is observed. However the apparent magnitude of the coupling constant is reduced, the overlap of the resulting multiplets is a less frequent problem.
The off resonance decoupled spectrum retains the couplings between the carbon atom and directly attached proton but effectively remove the couplings between the carbon and more remote protons.
In this technique, the frequency of a second radio frequency transmitter (the decoupler) is set either up field or down field from the usual sweep width of a normal proton spectrum (off resonance). In contrast, in a true decoupling experiment the frequency of the decoupler is set 10-1 coincide exactly with the range of proton resonances.
Furthermore in off resonance decoupling, the power of the decoupling oscillator is held low to avoid complete decoupling.
Fluorimetry
Fluoresence is caused by absorption of radiant energy and re-emission of some of this energy in the form of visible or UV light.
The light emitted always has higher wavelength than the incident light. In fluoresence the absorption and emission takes place with in a short time of the order of 10-12 s to 10-5 s. In phosphoresence the time delay is > 10-4 s to a few seconds. Both fluorescence and phosphorescence are put together as photo luminescence.
Intensity of fluorescent radiation is proportional to the concentration of the substance.
Applications of Fluorimetry:
Fluorimetry is used when there is no colorimetric method available, In inorganic chemistry the most frequent applications are for the determination of metal ions as fluorescent organic complexes. Uranium compounds fluoresce as such. Oxime (8-hydroxyl quinoline) complexes of Al, Zn, Mg fluoresce.
Other applications to determine quantitatively quinines, vitamins (B1 & B2).
The light emitted always has higher wavelength than the incident light. In fluoresence the absorption and emission takes place with in a short time of the order of 10-12 s to 10-5 s. In phosphoresence the time delay is > 10-4 s to a few seconds. Both fluorescence and phosphorescence are put together as photo luminescence.
Intensity of fluorescent radiation is proportional to the concentration of the substance.
Applications of Fluorimetry:
Fluorimetry is used when there is no colorimetric method available, In inorganic chemistry the most frequent applications are for the determination of metal ions as fluorescent organic complexes. Uranium compounds fluoresce as such. Oxime (8-hydroxyl quinoline) complexes of Al, Zn, Mg fluoresce.
Other applications to determine quantitatively quinines, vitamins (B1 & B2).
Heavy metal Manganese (Mn)
Manganese is an essential micro-nutrient for plants and animals. Its deficiency in humans may cause diabetes, nervous instability, convulsions, disorders of cartilaginous, growth in infants and children, and rheumatoid arthritis exposure to layer than trace concentration of Manganese can be toxic.
The metal is a respiratory irritant and systematic poison when inhaled mainly as oxides in excessive amounts. The major source of manganese pollution is the processing of iron ores, in which manganese is present in significant concentrations.
Industrial toxicity through inhalation of manganese particulates is of two types.
a) The first is due to acute short term exposure and is known as manganese pneumonity persons working in plants with high concentrations of manganese dust an incidence of respiratory diseases 30 times greater than normal. Pathological changes include epithelialneerosin followed by mono nuclear proliferation.
b) The second and more serious disease is caused by chronic inhalation of MnO2, generally over a period of more than 2 years it involves the central nervous system chronic manganese poisoning known as manganism leads to psychiatric disorders characterized by irritability difficulty in walking, speech disturbances, and compulsive behavior that may include running, fighting and singing. If the condition persists a mask like face, retropulsion or propulsion and a Parkinson like syndrome develops. In addition to the injuries to central nervous system, liver cirrhosis has been observed frequently, victims of chronic manganese poisoning recovers slowly, even when exposure is removed.
The metal is a respiratory irritant and systematic poison when inhaled mainly as oxides in excessive amounts. The major source of manganese pollution is the processing of iron ores, in which manganese is present in significant concentrations.
Industrial toxicity through inhalation of manganese particulates is of two types.
a) The first is due to acute short term exposure and is known as manganese pneumonity persons working in plants with high concentrations of manganese dust an incidence of respiratory diseases 30 times greater than normal. Pathological changes include epithelialneerosin followed by mono nuclear proliferation.
b) The second and more serious disease is caused by chronic inhalation of MnO2, generally over a period of more than 2 years it involves the central nervous system chronic manganese poisoning known as manganism leads to psychiatric disorders characterized by irritability difficulty in walking, speech disturbances, and compulsive behavior that may include running, fighting and singing. If the condition persists a mask like face, retropulsion or propulsion and a Parkinson like syndrome develops. In addition to the injuries to central nervous system, liver cirrhosis has been observed frequently, victims of chronic manganese poisoning recovers slowly, even when exposure is removed.
Uses of Crystal Field Theory
- Crystal field theory provides a basis of understanding and predicting the variations in magnetic moments with temperature as well as detailed magnetic properties of certain complexes.
- While valence bond theory predicts magnetic behavior up to the point of indicating the number of unpaired electrons crustal field theory gives the detailed explanation of magnetic properties.
- Crystal field theory also makes possible a clearer understanding of certain stereo chemical, thermodynamic and kinetic features of complex formation.
- Most importantly, it gives an idea of the allowed d-d transitions which necessarily involve excited energy states and hence depend on the d-orbital splitting.
Pasteurization of Milk.
The aim of pasteurization of milk is to get rid of any disease-producing bacteria it may contain and to reduce substantially the total bacterial count for improved keeping qualities. pasteurization of milk destroys approximately 99% of all bacteria and also most of the yeast's and molds. Generally two methods are employed in pasteurization.
One method consists of holding every particle of milk for 30 min at 61.7 degree centigrade followed by rapid cooling. This is a batch process.
In high temp short time (HTST) method the milk is held for not less than 15 seconds at 71.7c. This is a continuous process. Ultra-high temperature treatment at 93.4 degree centigrade for 3 sec are also employed.
As pasteurized milk is not sterile it must be quickly cooled after pasteurization to prevent multiplication of surviving bacteria. The thoroughness of pasteurization of milk is ascertained by testing for the alkaline phosphate activity in milk.
One method consists of holding every particle of milk for 30 min at 61.7 degree centigrade followed by rapid cooling. This is a batch process.
In high temp short time (HTST) method the milk is held for not less than 15 seconds at 71.7c. This is a continuous process. Ultra-high temperature treatment at 93.4 degree centigrade for 3 sec are also employed.
As pasteurized milk is not sterile it must be quickly cooled after pasteurization to prevent multiplication of surviving bacteria. The thoroughness of pasteurization of milk is ascertained by testing for the alkaline phosphate activity in milk.
To distinguish Oleomargarine from Butter.
Oleomargarine is a butter substitute used as a cooking and table fat. Combining different oils such as olive oil, refined and sometimes cottonseed oil makes it.
It is very difficult to distinguish between oleomargarine and butter. It is not possible in all cases to differentiate by simple tests. A carefully controlled chemical analysis by chemist is required if a positive result is required. However the following simple test known as "house hold foam test" can be used to limited extent.
The test consists of heating the suspected sample in a spoon over a slow flame. Oleomargarine boils with a marked noise and considerable sputtering, but produces little or no foam. Butter generally boils with less noise and foams vigorously. Renovated butter acts in the same way as oleomargarine.
It is very difficult to distinguish between oleomargarine and butter. It is not possible in all cases to differentiate by simple tests. A carefully controlled chemical analysis by chemist is required if a positive result is required. However the following simple test known as "house hold foam test" can be used to limited extent.
The test consists of heating the suspected sample in a spoon over a slow flame. Oleomargarine boils with a marked noise and considerable sputtering, but produces little or no foam. Butter generally boils with less noise and foams vigorously. Renovated butter acts in the same way as oleomargarine.
Subscribe to:
Posts (Atom)
Posts
