Friday, March 11, 2011
Hyperconjugation
It is a weak form of conjugation resulted from the ineraction of electrons in a sigma-bond with neighbouring empty pie-orbital or p-orbital resulting in an increased stability of the system.
Conjugation
Basically, Conjugation refers to joining together of two things.
In organic chemistry, we refer conjugation to a system which is joined together with alternate single and multiple bonds.
In organic chemistry, we refer conjugation to a system which is joined together with alternate single and multiple bonds.
Thursday, March 10, 2011
Miracle drug
Miracle drug is a type of drug that can cure incurable disease.
Initially, Aspirin and Penicillin and now Hercpetin, Breast Cancer Drug, is considered as miracle drug.
Initially, Aspirin and Penicillin and now Hercpetin, Breast Cancer Drug, is considered as miracle drug.
Wednesday, March 9, 2011
Efflorescence
It is the loss of water from a crystal.
It means “to flower out” in French.
It is the spontaneous loss of water (or solvent) from a hydrated or solvated salt to the atmosphere on exposure to air, which occurs when the aquous tension of the hydrate is greater than the partial pressure of the water vapor in the air.
Efflorescent:
Denoting a crystalline body that gradually changes to a powder by losing its water of crystallization on exposure to a dry atmosphere.
Explanation:
If the vapor pressure of a hydrated salt is greater than the pressure exerted by the water vapor in the surrounding atmosphere than the salt will attempt to attain equilibrium with its surroundings and therefore tend to lose water to form a lower hydrate or an anhydrous salt.
This phenomenon is known as efflorescence.
The pressure of water vapor in the atmosphere is about 13.33 x 10^2 N/m^2 at 293 K.
Therefore hydrates with vapor pressure greater than this will tend to exhibit efflorescence and be unstable provided that the lower hydrate that if formed still exerts a vapor pressure greater than the surrounding atmosphere.
If this is not so then water will be taken up from the atmosphere by the lower hydrate as fast as it is formed and the final equilibrium will depend on the rates at which water is lost or taken up the two hydrates.
Examples:
The behavior of the various forms of sodium carbonate may be represented by the following scheme:
Na2CO3.10H2O (v.p = 32 x 10^2 N/m^2 at 293K) --> (Spontaneous dehydration i.e. efflorescence) Na2CO3.H2O (v.p. = 16 x 10^2 N/m^2 at 293K)--> (efflorescence not observable because anhydrous salt is rapidly hydrated) --> Na2CO3 (anhydrous) (v.p. = 0)
Since the vapor pressure exerted by the decahydrate is much greater than that of normal atmosphere. It loses water by the process of efflorescence and is converted to the monohydrate.
The vapor pressure of the later is still above that of the atmosphere but further apparent loss of water does not occur. Since the anhydrous salt is rehydrated at a faster rate than dehydration of the monohydrate.
Similarly, vapor pressure of Glauber’s salt (Na2SO4.10H2O) normally exceed that of the water vapor in the atmosphere these salts effloresce and their surface assumes a powdry appearance. Blue stone or blue vitriol (CuSO4.5H2O)is a blue crystalline solid that when exposed to air slowly loses water of crystallization from its surface to form a white layer of anhydrous copper (II) sulfate.
Factors affecting efflorescence:
The vapor pressure of hydrated salts, and therefore the rate of efflorescence increases with rise in temperature.
Pressure of vapors.
Reduction of efflorescence:
Since the instability that arises from efflorescence is caused by the loss of water vapor. The common method of minimizing such deterioration involves the use of containers that present the loss of water vapor.
The additional precautions of using well filled containers with a minimum amount of atmosphere above the efflorescent material and storage in a cool place are also advisable.
It means “to flower out” in French.
It is the spontaneous loss of water (or solvent) from a hydrated or solvated salt to the atmosphere on exposure to air, which occurs when the aquous tension of the hydrate is greater than the partial pressure of the water vapor in the air.
Efflorescent:
Denoting a crystalline body that gradually changes to a powder by losing its water of crystallization on exposure to a dry atmosphere.
Explanation:
If the vapor pressure of a hydrated salt is greater than the pressure exerted by the water vapor in the surrounding atmosphere than the salt will attempt to attain equilibrium with its surroundings and therefore tend to lose water to form a lower hydrate or an anhydrous salt.
This phenomenon is known as efflorescence.
The pressure of water vapor in the atmosphere is about 13.33 x 10^2 N/m^2 at 293 K.
Therefore hydrates with vapor pressure greater than this will tend to exhibit efflorescence and be unstable provided that the lower hydrate that if formed still exerts a vapor pressure greater than the surrounding atmosphere.
If this is not so then water will be taken up from the atmosphere by the lower hydrate as fast as it is formed and the final equilibrium will depend on the rates at which water is lost or taken up the two hydrates.
Examples:
The behavior of the various forms of sodium carbonate may be represented by the following scheme:
Na2CO3.10H2O (v.p = 32 x 10^2 N/m^2 at 293K) --> (Spontaneous dehydration i.e. efflorescence) Na2CO3.H2O (v.p. = 16 x 10^2 N/m^2 at 293K)--> (efflorescence not observable because anhydrous salt is rapidly hydrated) --> Na2CO3 (anhydrous) (v.p. = 0)
Since the vapor pressure exerted by the decahydrate is much greater than that of normal atmosphere. It loses water by the process of efflorescence and is converted to the monohydrate.
The vapor pressure of the later is still above that of the atmosphere but further apparent loss of water does not occur. Since the anhydrous salt is rehydrated at a faster rate than dehydration of the monohydrate.
Similarly, vapor pressure of Glauber’s salt (Na2SO4.10H2O) normally exceed that of the water vapor in the atmosphere these salts effloresce and their surface assumes a powdry appearance. Blue stone or blue vitriol (CuSO4.5H2O)is a blue crystalline solid that when exposed to air slowly loses water of crystallization from its surface to form a white layer of anhydrous copper (II) sulfate.
Factors affecting efflorescence:
The vapor pressure of hydrated salts, and therefore the rate of efflorescence increases with rise in temperature.
Pressure of vapors.
Reduction of efflorescence:
Since the instability that arises from efflorescence is caused by the loss of water vapor. The common method of minimizing such deterioration involves the use of containers that present the loss of water vapor.
The additional precautions of using well filled containers with a minimum amount of atmosphere above the efflorescent material and storage in a cool place are also advisable.
Vitamin B12
It is used for Macrocytic anemia.
It is also called as cobalamin or cyanocobalamin. It is present in liver, milk, egg and fish. Physiologically active forms of vitamin B12 coenzymes are methylcobalamin and 5-deoxyadenosinecobalamine.
Daily requirement:
Daily B12 requirement is about 2 µg in normal adults.
Mechanism of action:
It acts as a co-factor in the formation of Succinyl-CoA from methylmalonyl-CoA.
Methylmalonyl-CoA is an intermediate product during the degradation process of many metabolites in the body. In the case of pernicious anemia, its amount is increased. Whereas, succinyl-CoA is a precursor in the synthesis of heme.
Accumulation of methylmalonyl-CoA leads to abnormal production of fatty acid as well as its incorporation to cell membranes. This causes demyelination of the nerve cells.
It acts as a co-factor in the formation of H4 folate and methionine leading to the formation of DNA.
Accumulation of 5-CH3-H4 folate leads to the deficiency of folate cofactors resulting in reduced DNA synthesis and megaloblastic anemia.
Administration:
It can be administered orally, IM or deep subcutaneously.
Pharmacokinetics:
Absorption:
Vitamin B12 gets bind to intrinsic factor (IF) and form a complex. This IF-B12 complex is then absorbed in distal ileum. This absorption is done by a very specific receptor mediated transport system.
Distribution:
Vitamin B12 is distributed to different cells of the body upon binding to transcobalamin II. It is stored in the liver in amount of 300-500 µg.
Elimination:
Normally, very little amount is excreted through urine or feces but upon parenteral administration large amount is found in urine.
Vitamin B12 deficiency:
Its deficiency causes pernicious anemia due to spoiled synthesis of red blood cells. Its deficiency can be caused by:
1. Low level of intake of Vitamin B12
2. Decreased absorption of vitamin due to less amount of intrinsic factor (IF) produced by gastric parietal cells
3. Lessened activity of the receptor for uptake of the vitamin from intestine
4. Non-specific malabsorption syndrome.
Therapeutic uses:
It is used in megaloblastic anemia and pernicious anemia as it is important in the formation of blood and growth. It is also important in proper neural functioning.
Dosage:
It is given in the dose of 100-1000 µg daily for 1-2 weeks than as a maintenance therapy the same dose is required once a month for life.
Adverse effects:
It has no adverse effects as extra amount is excreted via urine.
It is also called as cobalamin or cyanocobalamin. It is present in liver, milk, egg and fish. Physiologically active forms of vitamin B12 coenzymes are methylcobalamin and 5-deoxyadenosinecobalamine.
Daily requirement:
Daily B12 requirement is about 2 µg in normal adults.
Mechanism of action:
It acts as a co-factor in the formation of Succinyl-CoA from methylmalonyl-CoA.
Accumulation of methylmalonyl-CoA leads to abnormal production of fatty acid as well as its incorporation to cell membranes. This causes demyelination of the nerve cells.
It acts as a co-factor in the formation of H4 folate and methionine leading to the formation of DNA.
Accumulation of 5-CH3-H4 folate leads to the deficiency of folate cofactors resulting in reduced DNA synthesis and megaloblastic anemia.
Administration:
It can be administered orally, IM or deep subcutaneously.
Pharmacokinetics:
Absorption:
Vitamin B12 gets bind to intrinsic factor (IF) and form a complex. This IF-B12 complex is then absorbed in distal ileum. This absorption is done by a very specific receptor mediated transport system.
Distribution:
Vitamin B12 is distributed to different cells of the body upon binding to transcobalamin II. It is stored in the liver in amount of 300-500 µg.
Elimination:
Normally, very little amount is excreted through urine or feces but upon parenteral administration large amount is found in urine.
Vitamin B12 deficiency:
Its deficiency causes pernicious anemia due to spoiled synthesis of red blood cells. Its deficiency can be caused by:
1. Low level of intake of Vitamin B12
2. Decreased absorption of vitamin due to less amount of intrinsic factor (IF) produced by gastric parietal cells
3. Lessened activity of the receptor for uptake of the vitamin from intestine
4. Non-specific malabsorption syndrome.
Therapeutic uses:
It is used in megaloblastic anemia and pernicious anemia as it is important in the formation of blood and growth. It is also important in proper neural functioning.
Dosage:
It is given in the dose of 100-1000 µg daily for 1-2 weeks than as a maintenance therapy the same dose is required once a month for life.
Adverse effects:
It has no adverse effects as extra amount is excreted via urine.
Dispensing
Dispensing refers to the provision of medicine according to the prescription.
Following steps are involved in a Pharmacy setup:
1. Prescription: Medicines recommended by the physician as a remedy
2. Formulation: Darwing and expressing the medicines and ingredients of the prescription
3. Compounding: Preparing and mixing of the ingredients and/or medicines of the prescription
4. Dispensing: Giving the medicines to the patient. Medicines are given in a container with proper labelling. This label helps the patient for subsequent use of the medicine.
Dispensing may also involve the preparation of device for the use of patients.
Extemporaneous dispensing:Extemporaneous dispensing refers to the compounding and dispensing of medicines with little or no preparation in response to the stimulus of one's immediate environment.
Following steps are involved in a Pharmacy setup:
1. Prescription: Medicines recommended by the physician as a remedy
2. Formulation: Darwing and expressing the medicines and ingredients of the prescription
3. Compounding: Preparing and mixing of the ingredients and/or medicines of the prescription
4. Dispensing: Giving the medicines to the patient. Medicines are given in a container with proper labelling. This label helps the patient for subsequent use of the medicine.
Dispensing may also involve the preparation of device for the use of patients.
Extemporaneous dispensing:Extemporaneous dispensing refers to the compounding and dispensing of medicines with little or no preparation in response to the stimulus of one's immediate environment.
Tuesday, March 8, 2011
Search Methods
Search methods are used in optimization.
In these methods, the response surfaces are examined by different methods in order to determine the combination of independent variables, so that the optimum results can be obtained. Response surface methodology is used to determine the connection between different explanatory variables (independent variables) and one or more of the response variables (dependent variables).
Following steps are followed in the search methods:
1. A system is selected
2. Independent and Dependent variables are selected
3. Experiments are performed and product is tested
4. Data is submitted (to computer) for statistical and regression analysis
5. Specifications are set for feasibility program
6. Constraints are set for grid search
7. Grid search printouts are evaluated
8. Partial derivative plots (single or composite) and contour plots are evaluated.
In these methods, the response surfaces are examined by different methods in order to determine the combination of independent variables, so that the optimum results can be obtained. Response surface methodology is used to determine the connection between different explanatory variables (independent variables) and one or more of the response variables (dependent variables).
Following steps are followed in the search methods:
1. A system is selected
2. Independent and Dependent variables are selected
3. Experiments are performed and product is tested
4. Data is submitted (to computer) for statistical and regression analysis
5. Specifications are set for feasibility program
6. Constraints are set for grid search
7. Grid search printouts are evaluated
8. Partial derivative plots (single or composite) and contour plots are evaluated.
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