Primary classes

A primary class of additives is that of the detergents. We will examine in turn the role they play in motor fuels and the chemical structures that are necessary. 

The basis orbitals coimnonly used in the LCAO-MO process fall into two primary classes ... 

Chemical Properties. Its two functional groups permit a wide variety of chemical reactions for lactic acid. The primary classes of these reactions are oxidation, reduction, condensation, and substitution at the alcohol group. 

Figure 2 illustrates the two primary classes of PCBs that exhibit this type of activity, namely the coplanar PCBs and their monoortho coplanar analogues. 

The physical characteristics of sewer deposits can be described in terms of individual particle and bulk properties. The hydraulic and structural conditions in the sewer, together with the nature of the inputs, will control the type of material that deposits at a given location. Crabtree (1989) has proposed a sewer sediment taxonomy that is relevant mainly in terms of physical properties but also to chemical and biological processes (Table 3.5). The taxonomy is based on four primary classes with a fifth class B comprising agglutinated or cemented class A material. 

Classincation of the Proteases. The classification of the proteases is based on their mechanism of catalysis (4), The four primary classes of proteases are the serine, aspartic, cysteine, and metalloproteases (5). This classification is based on the primary functional group found in the en me s active site. There are likely to be other proteases eventually characterized which will not precisely fit into this categorization scheme and additional categories will be needed. One example of a potential new category is the ATP-dependent proteinases (6), a group of proteinases which require ATP for activity. 

The primary class of stimulants for which there is a tremendous addiction problem is the sympathomimetic stimulants, which include cocaine, amphetamine, metham-phetamine (Desoxyti), methylphenidate Ritalin), and phenmetrazine. 

Effective pharmacological treatment of panic disorder began with the antidepressant imipramine, but today a variety of efficacious agents are available for treating the symptoms of panic disorder. The four primary classes of... 

Alpha receptors A primary class of receptors that are responsive to epinephrine and norepinephrine. Alpha receptors are subclassified into alpha-1 and alpha-2 receptors based on their sensitivity to various drugs. 

Muscarinic receptor A primary class of cholinergic receptors that are named according to their affinity for the muscarine toxin. Certain cholinergic agonists... 

Hypotheses for the formation of odids There are three primary classes of hypotheses for the processes responsible for the existence of odids. They are based on bacterial-mechanical, algal, or chemical mechanisms for odid formation. Some investigators have made hybrid models involving more than one of these mechanisms. Because the previously cited papers cover the literature up to about 1980, we will only present these hypotheses in a general manner and not attempt to reference the large number of papers relevant to the topic. 

The present classificatory system does not recognize as a primary class those separations depending on selective chemical reactions or electronic excitations (e.g., of isotopes). The reactions do not, in fact, constitute separation but are preparation steps designed to convert one or several... 

It is probably necessary to make a primary operational distinction of reaction classes based on the phase (or phases) of matter involved thus (1) homogeneous, liquid phase (2) gas phase (3) solid phase (4) heterogeneous. A basic subclassification distinguishes between reactions in which the reactants are chemically different from the prodncts, as in equations (1) and (2), and reactions in which the reactants and prodncts involve the same chemical species, as in equations (3) and (4) when (N4) = ( N4). Eqnations (1) and (2) are examples of cross electron-transfer reactions (or cross-reactions), while eqnations (3) and (4) are examples of self-exchange electron-transfer reactions when (N4) = ( N4). More generally, subclassifications of the primary classes are commonly based on energy or free energy considerations such as ... 

Chemical fractionation of whole products and by-products from synthetic fuel production affords a logical first step in the evaluation of these materials for biological activity and the subsequent prediction of health hazards. Aliphatic and aromatic hydrocarbons, along with smaller amounts of heteroatomic species, constitute the bulk of all crude product materials and define a primary class separation need. Subfractionation of these fractions can lead to identification of bioactive components, Aliphatics are separated from the entire sample by a simple liquid chromatographic elution scheme. Aromatic compounds can be isolated by a cyclo-hexane-dimethylsulfoxide solvent partitioning scheme, A Sephadex LH-20 gel separation scheme appears feasible for the fractionation of crude liquids into aliphatic-aromatic, lipophilic-hydrophilic, polymeric, and hydrogen bonding classes of compounds. 

T cells are further divided into three primary classes helper T cells (T-H cells), cytotoxic T cells (ctx T cells), and T suppressor T cells. T-H cells augment B cell responses to bacterial antigens. Cytotoxic T cells attack viral antigens and some early cancer cells. And suppressor T cells halt immune cell functions, allowing the body to rest. 

The information in this text was formatted in a consistent manner to make a usable bench handbook for a chemist performing real-world analyses. Compounds were chosen trying to obtain a representative sampling of all the primary classes of additives. 

TABLE 5.1 The Water Quality Requirements for Various Primary Classes of End Use"... 

At the highest level of classification, natural (= biological) products can be divided into two super classes, namely, primary and secondary metabolites. The primary class of natural products include nucleic acids,... 

Teachers for primary classes are usually trained in colleges of education, which may or may not be attached to the university. Teachers for senior secondary classes have followed a science course in a university. 

---