Chemical structure response

The degree of light-induced photoyellowing measured on mechanical pulps depends to some extent on the time between the actual irradiation and the brightness measurement. For example, if a sheet is kept for a certain time after accelerated irradiation the brightness increases slowly to reach a new upper limit. If the irradiated and stared sheet is irradiated a second time, the brightness decreases again, i.e. the pulp shows a photochromic effect. The extent of the photochromic effect depends both on the type of mechanical pulp used and on the irradiation time. In this study we have tried to evaluate which factors affect the photochromic effect and to identify the chemical structures responsible. 

EM also has a motilin-like stimulating activity on gastrointestinal smooth muscles [39]. Therefore, the inhibitory effect on cytokine expression in human cells summarized here may be a third bioactivity of the macrolide antibiotic. We recently reported that some of these derivatives have inhibitory effect on IL-8 production by human airway epithelial cells [72], These analogues also showed inhibitory action on the activation of NFkB and AP-1 assessed by EMSA (M. Desaki etal., unpublished observations, January 2001). Characterization of the chemical structure responsible for its potential would be important to pursue and further investigation for the molecular mechanism would be necessary for a possible new type of anti-inflammatory agent. 

The relationship between chemical structures and their physical performance is one of the central topics of polymer physics. lUPAC has recommended a whole set of names to describe the detailed chemical structures of polymer chains and their derivatives. However, in our daily communication, people prefer to use the popular names of polymers reflecting their characteristic physical performances, such as high-density polyethylene (HOPE), foamed polystyrene, thermoplastic elastomers, liquid crystal polymers, conductive polymers, and polyelectrolyte. Such terminology allows us to comprehend quickly the basic characteristics of chemical structures responsible for their specific physical properties. 

For CW spectra and FT spectra of H nuclei the area under each absorption peak is proportional to the number of H nuclei present in it this is not true for nuclei however. Thus knowledge of the ratio of the peak areas in a pmr spectrum helps in the identification of the chemical structure responsible for each of the peaks. Because of this, all nmr spectrome-... 

Morris, M.D. et al (2004) Bone tissue ultrastructural response to elastic deformation probed by Raman spectroscopy. Faraday Discuss., 126, 159-168 discussion 169-183. de Carmejane, O. et al. (2005) Bone chemical structure response to mechanical stress studied by high pressure Raman spectroscopy. Calcif. Tissue Int., 76 (3), 207-213. 

PPy films are thermally and oxidatively reactive, and materials that are in the main indistinguishable by bulk analytical methods present different electrical stability, although chemical reaction does not lead inevitably to changes of conductivity. For these reasons, and since synthetic conditions can subtly vary from one laboratory to another, there is a pressing need for a better understanding of the chemical structures responsible for conduction and their distribution within the film. 

Oxidation of P-nicotinamide adenine dinucleotide (NADH) to NAD+ has attracted much interest from the viewpoint of its role in biosensors reactions. It has been reported that several quinone derivatives and polymerized redox dyes, such as phenoxazine and phenothiazine derivatives, possess catalytic activities for the oxidation of NADH and have been used for dehydrogenase biosensors development [1, 2]. Flavins (contain in chemical structure isoalloxazine ring) are the prosthetic groups responsible for NAD+/NADH conversion in the active sites of some dehydrogenase enzymes. Upon the electropolymerization of flavin derivatives, the effective catalysts of NAD+/NADH regeneration, which mimic the NADH-dehydrogenase activity, would be synthesized [3]. 

Due to the chemical structure, fimctionality and composition of their constituents, ordinary variations of the processing conditions as well as the quality of the raw materials have been observed to lead to changes of the fine structure which are often responsible of lower ageing resistence of the polymer. The data reported here correlate the morphology of some widely utilized epoxy matrices to the informations that can be obtained from the study of the sorption behaviours. 

The degradation of the matrix in a moist environment strongly dominates the material response properties under temperature, humidity, and stress fatigue tests. The intrinsic moisture sensitivity of the epoxy matrices arises directly from the resin chemical structure, such as the presence of hydrophilic polar and hydrogen grouping, as well as from microscopic defects of the network structure, such as heterogeneous crosslinking densities. 

Different characteristics of the chemical structure of different elastomers cause variations in their individual responses to these external influences. The design engineer deals with behavior occurring as a result of this general structural nature. 

Electric field sensitive dyes respond to changes in electrical membrane potential by a variety of different mechanisms with widely varying response times depending on their chemical structure and their interaction with the membrane. An understanding of the mechanisms of dye response and their response mechanisms is important for an appropriate choice of a probe for a particular application. The purpose of this chapter is, therefore, to provide an overview of the dyes presently available, how they respond to voltage changes, and give some examples of how they have been applied. Finally, because there is still scope for the development of new dyes with improved properties, some directions for future research will be discussed. 

The chemical structures of these fibers provide an explanation for the differences in the response of these materials to water. 

Whereas molecular design is a strategy applicable to the chemical level of epitope-paratope interactions, it cannot be used for optimizing the many cellular interactions required for achieving an immune response that leads to infectivity neutralization of a pathogen. As a result, the future development of vaccines will continue to rely more on the empirical testing of the protection afforded by candidate vaccine preparations than on the rational design of biomolecules defined in a reductionist manner by their chemical structure. 

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