Primary initiation

The easiest way to extract a set of objects from the basic dataset, in order to compile a test set, is to do so randomly. This means that one selects a certain number of compounds from the initial (primary) dataset without considering the nature of these compounds. As mentioned above, this approach can lead to errors. 

As a general rule the sulfenamides exhibit faster cure rate than the thiazoles. If secondary accelerators are used, dithiocarbamates are scorchiest and give the fastest cure followed by the thiurams, then the guanidines. Figure 6 summarizes these comparisons to show a series of natural mbber (NR) recipes using either a thiazole (MBTS) or sulfenamide (TBBS) primary accelerator in combination with the various secondary accelerators (21). In this study, the initial primary accelerator levels were selected to produce nearly equivalent modulus or state of cure in the NR. 

Owing to the reactions of the initial primary radiolysis products among themselves, as in Eqs. (11-58)—(11-62), it is usually necessary to add another reagent to remove the unwanted ones. For example, to study reactions of e alone, one must work in neutral or basic solution to avoid its destruction by HsO+ (see Problem 11-12). Also, hydroxyl radicals and hydrogen atoms are removed from the system by prior addition of terf-butyl alcohol to give noninterfering products,... 

All the methods involve preparation of an initial, primary, hydrated, viscous solution referred to as base gel or linear gel. 

If a secondary method is required during early phase development, a level 3 method is developed and validated to support phase 2b or early phase 3 clinical studies. This method should be capable of separating all components of interest identified up to this stage of pharmaceutical development. In cases where the initial primary method is still viable, the level 1-level 2 method may be maintained. As in early development, the use of an orthogonal method to evaluate DS generated via new synthetic schemes and to evaluate new formulations remains an important means of assuring that the primary method is sufficient for characterizing DS and DP. 

Osteoporosis is a metabolic bone disease characterized by low bone mass and micro-architectural deterioration of bone tissue. This will lead to bone fragility and consequent increase in bone fracture risk. Mean bone mineral density (BMD) is measured with dual X-ray absorptiometry (DEXA) and expressed in Tsc (Tscore). WHO standards are a Tsc that is 1 standard deviation (SD) below mean BMD is graded as normal bone, Tsc between 1 and 1.5 SD below mean BMD is graded as osteopenia and a Tsc of more than 2.5 SD below mean BMD is graded as osteoporosis. When the Tsc is below 1.5 SD mean BMD prevention of osteoporosis must be initiated. Primary osteoporosis is caused mainly by hormone deflciency in both women and men. Secondary osteoporosis may result from endocrine, metabolic, nutritional and autoimmune causes or from immobility because of trauma. Also the use of medicaments such as corticosteroids may be contributing. 

Primary explosives have low values for the activation energy and collision factor compared with secondary explosives. Therefore, it takes less energy to initiate primary explosives and makes them more sensitive to an external stimulus, i.e. impact, friction, etc., whereas secondary explosives have higher values for the activation energy and collision factor, and are therefore more difficult to initiate and less sensitive to external stimulus. 

Larger scale secondary screening experiments performed on a focused 96-member amine-ether library demonstrated high temperature ethylene-l-octene copolymerization capabilities for this catalyst class, and led to catalysts with significant performance improvements over the initial primary screening discovery (Fig. 12.6). 

Explosives are classified as primary or secondary, based on their susceptibility to initiation. Primary explosives, which include lead azide and lead styphnate, are highly susceptible to initiation. Primary explosives often are referred to as initiating explosives because they can be used to ignite secondary explosives. Secondary explosives, which include 2,4,6-trinitrotoluene (TNT), hexahydro-l,3,5-trinitro-l,3,5-triazine (RDX or cyclonite), high melting explosives (HMX) like octahydro-l,3,5,7-tetranitro-l,3,5,7-tetrazine (HMX),... 

Fundamental Processes That Control Aerosol Generation and Transport. The size of the aerosol drops in the initial (primary) aerosol depends on the design of the nebulizer, the nebulizer gas flow rate, and, to a lesser extent, the sample... 

In the following table are data on the dependence of the average floccule radius, achieved after 500 s of flocculation, on the initial primary particle number density for a transport-controlled flocculation process. Estimate the fractal dimension of the floccules formed. (Answer D 1.8, based on a log-log plot.)... 

Explosives in which the detonation is initiated by the detonation impact of an initial (primary) explosive. Accordingly, this definition includes all explosives used to obtain blasting effects. 

Secondary explosives (also known as high explosives = HEs) unlike primary explosives can not be initiated simply through heat or shock. In order to initiate primary explosives have to be used, whereby the shockwave of the primary explosive initiates the secondary. However, the performance of the secondary explosive is usually higher than that of the primary (see Tab. 2.1). Typical currently used secondary explosives are TNT, RDX, HMX, NQ and TATB (see also Tab. 1.2) and, for civil applications, HNS and NG e.g. in the form of dynamite for commercial use. 

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