Acidic constituent

Individual ammo acids differ m their acid-base properties This is important m peptides and proteins where the properties of the substance depend on its ammo acid constituents especially on the nature of the side chains It is also important m analyses m which a complex mixture of ammo acids is separated into its components by taking advantage of the differences m their proton donating and accepting power... 

Cascara sagrada is used as a cathartic. It is most useful when prepared as a fluid extract, and tends to be a mild laxative causing Htfle discomfort. However, on prolonged use it may result in characteristic melanotic pigmentation of the rectal mucosa. The bitter taste can be lessened, owing to neutralization of the acid constituents, if the ground substance is moistened and mixed with magnesium or calcium hydroxide. This treatment may lessen the potency of the preparation. 

Fluxes are usually added in the form of either limestone or dolomite. The fluxes provide the basic constituents (CaO and MgO) needed to balance the acid constituents (Si02 and AI2O2) from the coke and ore. These are the four primary oxides which form the slag, although minor amounts of other oxides such as MnO, Na20, K2O, P2 S Ti02, and sulfur are also present. Proper adjustment of the slag chemistry is necessary to obtain the desired... 

Plasticizer Efficiency. This is a measure of the concentration of plasticizer required to impart a specified softness to PVC. Such a softness of material may be measured as a British Standard Softness (BSS) or a Shore hardness (Pig. 1). Por a given acid constituent of plasticizer ester, ie, phthalate, adipate, etc, plasticizer efficiency decreases as the carbon number of the alcohol chain increases, eg, for phthalate esters efficiency decreases in the order DBP > DIHP > DOP > DINP > DIDP > DTDP. An additional six parts per hundred in PVC of DIDP rather than DOP is required to give a hardness of Shore 80 when ah. other formulation ingredients remain constant. The consequence of this depends on the overall formulation and product costs. In addition to size of the carbon number of the alcohol chain, the amount of branching is also significant the more linear isomers are of greater efficiency. 

Choice of the acid constituent can also be significant. For equivalent alcohol constituents, phthalate and adipate esters are approximately equivalent but both are considerably more efficient than the trimeUitate equivalent. 

Low Temperature Performance. The abihty of plasticized PVC to remain flexible at low temperatures is of great importance in certain apphcations, eg, external tarpaulins or underground cables. Eor this property the choice of the acid constituent of the plasticizer ester is also important. The linear aUphatic adipic, sebacic, and azeleic acids give excellent low temperature flexibiUty compared to the corresponding phthalates and trimeUitates (Pig. 3). 

Overall Assessment of Properties. Table 3 shows the effect for each criterion of increasing plasticizer concentration, increasing the size of the plasticizer molecule, increasing the linearity of the plasticizer molecule, and changing the acid constituent of the ester. An I indicates improved performance for a particular property, a P indicates poorer performance. I and P in parentheses indicate that any changes tend to be marginal. 

The alkahes do not sequester heavy-metal ions and have Httie soil-suspending effect. They are effective in maintaining a high pH and saponify the acidic constituents of soil and thus promote cleaning. In the cleaning of ceramics, glass, and metal surfaces, however, the alkahes act as primary detergents even in the absence of surfactants in these systems. 

Acid deposition refers to the transport of acid constituents from the atmosphere to the earth s surface. This process includes dry deposition of SO2, NO2, HNO3, and particulate sulfate matter and wet deposition ("acid rain") to surfaces. This process is widespread and alters distribution of plant and aquatic species, soil composition, pH of water, and nutrient content, depending on the circumstances. 

These compounds have been extensively investigated because they are important nucleic acid constituents. Uracil has been shown conclusively to exist predominantly as pyrimidine-2,4-dione (99) both by a refined X-ray crystallographic technique in which the positions... 

It is the acid constituent of the ester forming almost the whole of wintergreen and birchbark oils, and is a crystalline solid melting at 159. Commercially pure samples, however, rarely melt at above 157°. It is prepared artificially on an enormous scale by heating sodium phenol, under pressure, with carbon dioxide. 

Anthranilic acid, or o-amidobenzoic acid, C H (NH2)(COOH),. is the-acid constituent of the ester found in neroli, petit-grain, jasmin, and mandarin oils. It is a solid crystalline substance melting at 145°. It is prepared artificially, and then converted into synthetic methyl anthranilate.. To prepare anthranilic acid, o-nitrobenzaldehyde is reduced by tin and hydrochloric acid to anthranil,... 

Saponification deterioration by softening of paint film caused by action of aqueous alkali, resulting from cathodic protection at excessively high current densities, on the fatty-acid constituents of the film. 

Nucleotide (Section 28. ) A nucleic acid constituent, consisting of a sugar residue bonded both to a heterocyclic purine or pyrimidine base and to a phosphoric acid. 

The stereochemistry of metal complexes of nucleic acid constituents. D. J. Hodgson, Prog. Inorg. Chem., 1977, 23,211-254 (175). 

Stereoselectivity in the binding of transition metal chelate complexes to nucleic acid constituents bonding and non-bonding effects. L. G. Marzilli and T. J. Kistenmacher, Acc. Chem. Res., 1977, 10,146-152 (29). 

According to Barbieri et al., it can not be excluded that some of the coordination sites are occupied by (Nj atoms of the nucleic acid constituents. The precipitate obtained from [Ph2Sn(IV)] would contain both the [R2Sn(IV)] -DNA complex and distannoxane [(Ph2SnCl)20]. The main products of the... 

Alternatively, rigidification of the y-peptide backbone to avoid H-bonds between nearest neighbors can be achieved by the introduction of an a,y9-unsaturation into the backbone of each y-amino acid constituent (vinylogous peptides) ]208, 209]. Recent ab-initio calculations suggested that the a,/9-unsaturated y-peptide backbone might support the formation of helices with large 19- and 22-membered H-bonded pseudocycles ]221]. 

Burtis, C. A. and Gere, D. R. "Nucleic Acid Constituents by Liquid Chromatography", Varian Aerograph, California, 1970. 

The identification of L-iduronic acid as the major glycuronic acid constituent of heparin proved to be a much slower process than the identification of the amino sugar residue. Although this compound was detected in acid hydrolyzates of heparin116117 and heparin oligosaccharides,118 its yield was usually poor, because of the drastic conditions used for the acid hydrolysis (which are known to lead to extensive destruction of uronic acid).119120 Also, L-iduronic acid escaped detection as L-idose in the hydrolyzates of carboxyl-reduced heparin, probably because L-idose is readily converted into 1,6-anhydro-L-idose under the usual hydrolytic conditions. 

The fatty acid constituents of phosphodiglycerides can vary considerably in nature among a number of different chain lengths and points of unsaturation. A given isolated phosphatidyl... 

By contrast, a given synthetic preparation of a major phospholipid possesses fatty acid constituents all of identical chain length and unsaturation. A synthetic PC derivative can be purchased that contains only, for instance, 1,2-dimyristoyl (C14) fatty acid substitutions on its glyceryl... 

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