General application properties

Crospovidone possess a series of properties that are used in the manufacture of different pharmaceutical products and dosage forms (Table 130). 

The most important property of crospovidone as an auxiliary is its disintegration and dissolution enhancing effect, which can be used in tablets, granules and hard gelatin capsules 

Its ability to form complexes is useful in solid and liquid dosage forms. 

The improvement brought about by crospovidone in the dissolution of insoluble drugs is particularly useful for tablets and granules. 

The use of micronized/fine powder crospovidone as an active substance against diarrhoea depends on its ability to form complexes, as does the use of crospovidone ( PVPP ) in removing polyphenols from wine, beer and plant extracts. The 

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In addition to the use of a melting point determination as a criterion of purity, an equally valuable application is for the identification of oiganic compounds. If the melting point is known within one degree, the major proportion of possible substances is immediately eliminated from consideration. The study of the general chemical properties of the compound and a mixed melting point determination (Section 1,17) will largely establish the identity of the compound. 

Although the general electrical properties of the polycarbonates are less impressive than those observed with polyethylene they are more than adequate for many purposes. These properties, coupled with the heat and flame resistance, transparency and toughness, have led to the extensive use of these resins in electrical applications. 

The widely observed lack of precise correlations among properties that chemical experience leads us to believe are somehow related to polarity has two important meanings First, it tells us that no single property may be taken as a generally applicable measure of polarity. Second, it conveys the message that some combination of the properties may capture the essence of what we mean by polarity. 

The Group 1 elements are soft, low-melting metals which crystallize with bee lattices. All are silvery-white except caesium which is golden yellow "- in fact, caesium is one of only three metallic elements which are intensely coloured, the other two being copper and gold (see also pp. 112, 1177, 1232). Lithium is harder than sodium but softer than lead. Atomic properties are summarized in Table 4.1 and general physical properties are in Table 4.2. Further physical properties of the alkali metals, together with a review of the chemical properties and industrial applications of the metals in the molten state are in ref. 11. 

The rest of this chapter will focus primarily on results using the soluble PPV-based polymer MEH-PPV. The results obtained for MEH-PPV are typical of the conjugated polymers used in LEDs. The models and results presented are generally applicable. They describe the operation of a wide range of polymer LEDs if the appropriate polymer film properties arc used. 

Altered synaptic properties Numerous changes in the properties of inhibitory (GABAergic) and excitatory (glutamatergic) synapses have been reported. While the simple adage of an imbalance between inhibitory and excitatory neurotransmission in epilepsy is not generally applicable, some forms of inhibition are lost or impaired in epilepsy. Likewise, an increased function of glutamate receptors has been demonstrated in some brain areas. 

Among the first desirable properties of models are economy in the number of parameters that describe the essential properties of an operation, general applicability to a variety of problems, and successful prediction. 

In general, those properties of industrial interest that are related to the electrochemical rates change several orders of magnitude when the conditions of synthesis are improved and when a solvent suitable for the specific application is used to produce the polymeric gel. We found this to be the case in our laboratory between the first and second generation of artificial muscles, with electrochromic films, or with specific energies. 

The polymer is based on a simple head-to-tail arrangement of monomer units and is amorphous, since the specific position of the benzene ring is somewhat variable and hence inhibits crystallisation. Despite its generally desirable properties, for many applications it is considered too brittle. Because of this, a number of approaches have been made to modify the mechanical properties of poly (styrene). The most successful of these have been (i) copolymerisation and (ii) the addition of rubbery fillers. 

Since the hardness test involves a substantial component of plastic deformation, hardness values are linked with tensile strength and not with yield strength when correlation between hardness and tensile properties are carried out. This appears to be a relationship between the hardness and tensile properties are carried out. There appears to be a relationship between he hardness of a metal and its tensile strength, but no general application has been found to exist. However, the following empirical relationship appears to hold fairly well for most steels, other than heavily cold worked steels or austenitic steels. 

Derivatives of 1,3-diphenylpyrazoline have been used to brighten cellulose acetate (section 11.7) and acrylic fibres (section 11.11.1) as well as nylon. There has been much study of the effects of substituents on application properties and some general rules can be formulated ... 

Among these reactions, the cycioadditions play a central role because of their general application, and for the unequalled property of the possible introduction of two new carbon-carbon or carbon-heteroatom bonds in the same step or process. 

For general application of these chiral ligands, see (a) Kagan, H. B. Chiral Ligands for Asymmetric Catalysis in Morrison, J. D. ed. Asymmetric Synthesis, vol. 5, Chap. 1, Academic Press, New York, 1985. (b) Kagan, H. B., Sasaki, M. Optically Active Phosphines Preparation, Uses and Chiroptical Properties in Hartley, F. R. ed. The Chemistry of Organo Phosphorous Compounds, John Wiley Sons, New York, 1990, vol. 1, Chap. 3. 

We find that the degree of para-selectivity obtainable depends uniquely on the activity and diffusion characteristics of the catalyst, independent of how these properties are obtained. While we will discuss these relationships with regard to STDP, the principles involved are generally applicable to those reactions over ZSM-5 where dialkylaromatic products are formed. 

Shortly after Perkin had produced the first commercially successful dyestuff, a discovery was made which led to what is now the dominant chemical class of dyestuffs, the azo dyes. This development stemmed from the work of Peter Griess, who in 1858 passed nitrous fumes (which correspond to the formula N203) into a cold alcoholic solution of 2-aminO 4,6 dinitrophenol (picramic acid) and isolated a cationic product, the properties of which showed it to be a member of a new class of compounds [1]. Griess extended his investigations to other primary aromatic amines and showed his reaction to be generally applicable. He named the products diazo compounds and the reaction came to be known as the diazotisation reaction. This reaction can be represented most simply by Scheme 4.1, in which HX stands for a strong monobasic acid and Ar is any aromatic or heteroaromatic nucleus. 

Supercritical fluid chromatography employs supercritical fluid instead of gas or liquid to achieve separations. Supercritical fluids generally exist at conditions above atmospheric pressure and at an elevated temperature. As a fluid, the supercritical state generally exhibits properties that are intermediate to the properties of either a gas or a liqiud. Chapter 16 discusses various advantages of SFC over GC and HPLC and also provides some interesting applications. 

Good general fastness properties make (J-naphthol pigment lakes suitable candidates primarily for the printing inks and plastics industry. Their primary area of application varies according to the type. (J-Naphthol pigment lakes are also employed in paints and in emulsion paints, but to a lesser degree. 

Properties having general applicability to a range of applications are, not surprisingly, those most commonly measured. It should be noted that the advantage of wide applicability is negated if the parameters in question are inferior, for example because of low sensitivity. 

A second method of activating the acid for esterification (see Section 7.6) is as the mixed anhydride. The mixed-anhydride reaction had been employed decades ago for preparing activated esters. However, it was never adopted because of its unreliability and the modest yields obtained. The method was fine-tuned (Figure 7.12), after reliable information on the properties of mixed anhydrides was acquired (see Section 2.8). Tertiary amine is required for esterification of the mixed anhydride to occur. The method is generally applicable, except for derivatives of asparagine, glutamine, and serine with unprotected side chains. The base also prevents decomposition that occurs when the activated derivative is a Boc-amino acid (see... 

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