Chemicals synergistic action

There are in addition several other factors that accelerate corrosion and must betaken into account these include crevices, galvanic coupling, tensile stress, aeration, presence of impurities, surface finish, etc. If these were also taken into consideration then several million experiments would have to be performed to compile such data. There are many instances where two or more chemicals exert a marked synergistic action such that low dissolution rates obtained in either environment become much greater in the presence of both. Further, the corrosiveness of a chemical will be affected by the presence of certain impurities, which may act as either accelerators or inhibitors. To take all these factors into account would add to an already impossible task and as Evans has remarked, There are not enough trained investigators in the world to obtain the empirical information to cover all combinations of conditions likely to arise . Unfortunately corrosion science has not yet reached the stage where prediction, based on a few well established laws, allows selection of materials to be made without recourse to a vast amount of data. 

There are other such scenarios that can be proposed. Evidence exists for both additive and synergistic actions. There is nothing magical about mixtures. The effects of mixtures can be explained in terms of the actions of the individual chemicals, all of which obey the usual physicochemical laws.3°... 

Kiuchi, F., Goto, Y., Sugimoto, N., Akao, N., Kondo, K. and Tsuda, Y. (1 993) Nematocidal activity of turmeric synergistic action of curcuminoids. Chemical and Pharmaceutical Bulletin 41, 1 640-1643. 

The NCSDs of Japan, Korea and the Philippines have played various roles and served different purposes. They have demonstrated the potency of co-ordinated and synergistic actions and contributed to their respective country s sustainable development processes. The Vietnam NCSD is still in its infancy stage but it has already served as a venue for consultation and co-ordinated action for the implementation of VA 21. The NCSDs could serve as the institutional mechanism for chemicals safety and management at the national level. 

Synergistic action is often seen with drugs. Almost all cases of increased hexo-barbital sleeping time or zoxazolamine paralysis time by other chemicals could be described as synergism or potentiation. Synergism may also result from competition for binding sites on plasma proteins or for the active secretion mechanism in the renal tubule. 

All of these accelerating effects were found to occur only in the presence of light. Since acid alone is also known to degrade nylon (12, 13) it is reasonable to suspect a synergistic action by light, humidity, heat, and aqueous acid (i.e. acid rain conditions) on the chemical and physical properties of the nylon fabric. 

Currently, researchers are trying to increase the low antimicrobial activity of chitosan to compare with commercially used chemicals. The recent advances include the use of composites and other biologically active substances (Table 3.3) that are known antimicrobial agents. The expected outcome is an increased antimicrobial effect due to the synergistic action of both antimicrobial agents. Moreover, the use of lesser synthetic agents to improve the naturally-derived polymer can be both economical and attractive. 

Specialty chemicals are complex mixtures whose value lies in the synergistic action of their ingredients. Here the application technology is decisive for market success. The manufacturer can no longer produce all ingredients, which can lead to a certain state of dependence. Strategic factors for successfiil manufacturers are [Felcht 2000, Willers 2000) ... 

Alcan Chemicals supply their Flamtard materials as alternatives to antimony trioxides for synergistic action in conjunction with various polymer systems. Flamtard H grades are used in halogenated polymer systems. They are thermally stable up to 200 °C and are particularly suitable for use with brominated polyesters, PVC and chlorinated PE. Flamtard S is thermally stable in all polymer systems. 

The nucleosides GMP, IMP and XMP are known to enhance food flavor. They display a synergistic action with soditim glutamate (Demain, 1968). Nucleotide derivatives are recommended for the treatment of thromboses. Inosine (under the name Riboxin) is a pharmaceutical agent used in the treatment of various heart and liver diseases in Russia. Ribosides and adenine support high levels of ATP in erythrocytes. Deoxyribonucleotides are used in chemical syntheses of some antitumor and antiviral preparations (Sidermene et al., 1985). In addition, 2-deoxyribonucleotides (-sides) serve as substrates for enzymatic and chemical syntheses of specific oligodeoxyribonucleotides, which at present are widely used as biosensors (Efremenko et al, 1990). 

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