Structural parameters affecting the

Structural Parameters Affecting the Brittleness of Polymer Glasses and Composites... 

Since the former theoretical predictions of push-pull substituted phthalocyanines as candidates for second-order NLO properties, some work has been devoted to prepare and study different substituted derivatives with the aim to establish the key structural parameters affecting the NLO response. Some revisions have already been done on the second-order NLO behavior of phthalocyanines [16, 17, 31]. For most of the unsymmetrically substituted push-pull compounds (planar conjugated 7T-electron systems in the XZ plane), 2 symmetry may be assumed due to the... 

The details of the molecular structure of polymers profoundly influence the observed Tg s, as illustrated by Table 5-2, where we may contrast the Tg of polydimethyl siloxane, -123 °C, with that of poly(calcium phosphate), + 525 °C. At least approximately, we may separate the observed effects into intermolecular and intramolecular parts. The latter refer to structural parameters affecting the stiffness of the chain backbone we shall examine these first. 

Clearly, many structural parameters affect the viscosity of ionic liquids and a more exhaustive study is needed to rationalize flie different trends and to establish a correlation model for prediction. 

Examples of how this variety of structural parameters affects the development of silicone surfactants especially for liquid carbon dioxide blown foams, are many [39,40,41, 42] and this latest drive in surfactant development provides good examples of the important performance issues and how they can be addressed. 

A detailed evaluation of the structural parameters affecting the photophysical properties was performed for the didodecyloxy-substituted quinquephenyl rigid-flexible polyethers 60. More particularly, the odd-even effect was observed for dilute polymeric solutions by means of steady-state and time-resolved fluorescence anisotropy. The different orientations of the quinquephenyl chromophores, and subsequently of their luminescent dipoles, concerning the polymers with an odd number of methylene units x=7, 9, 11) and those with an even (x = 8, 10, 12) one, were found responsible for the observed strong deviations in frozen and dilute solutions, where the flexible aliphatic chains are forced to adopt a nearly sta ered, lower energy conformation. 

The suitability of epoxy group to react via ring opening mechanism catalyzed by a wide variety of experimental conditions is the primary reason for the wide applications based on epoxy resins. On the other hand the draw back of the ready reactivity is the difficulty to control the crosslinking density and other structural parameters affecting the properties of the materials. 

The cushioning and soft-feeling properties required for some car interior applications were achieved by matrix modification as well as by the structural parameters affecting the compression-deflection of the foamed material (i.e. density, open cell content, cell size). 

Structural Parameters Affecting the Glass Transition Temperature... 

To understand how these parameters affected the efficiency of the chemiluminescent reaction, we examined the mechanism originally proposed by Rauhut (26). As shown in Scheme 2, hydrogen peroxide reacts with an oxalate ester, such as 2,4,6-trichlorophenyl oxalate (TCPO), in a two-step process to form a reactive intermediate for which Rauhut suggested structure 1, the 1,2-dioxetanedione. The dioxetanedione then interacts with an acceptor (ACC) to produce two molecules of COj and the excited state of the acceptor. The last stage of the sequence is fluorescence emission from the acceptor. 

A question of practical interest is the amount of electrolyte adsorbed into nanostructures and how this depends on various surface and solution parameters. The equilibrium concentration of ions inside porous structures will affect the applications, such as ion exchange resins and membranes, containment of nuclear wastes [67], and battery materials [68]. Experimental studies of electrosorption studies on a single planar electrode were reported [69]. Studies on porous structures are difficult, since most structures are ill defined with a wide distribution of pore sizes and surface charges. Only rough estimates of the average number of fixed charges and pore sizes were reported [70-73]. Molecular simulations of nonelectrolyte adsorption into nanopores were widely reported [58]. The confinement effect can lead to abnormalities of lowered critical points and compressed two-phase envelope [74]. 

Affected by multiple scattering are, in particular, porous materials with high electron density (e.g., graphite, carbon fibers). The multiple scattering of isotropic two-phase materials is treated by Luzatti [81] based on the Fourier transform theory. Perret and Ruland [31,82] generalize his theory and describe how to quantify the effect. For the simple structural model of Debye and Bueche [17], Ruland and Tompa [83] compute the effect of the inevitable multiple scattering on determined structural parameters of the studied material. 

Racemisation is a chemical reaction, and its rate is different for each type of amino acid. An important fact is that this process is affected by many factors that influence the rate of change of the amino acids stereochemistry [106]. The main parameters affecting the racemisation process include the amino acid structure, the sequence of amino acids in peptides, the bound state versus the free state of the amino acids, the pH in the environment, the concentration of buffer compounds, the contact of the sample with clay surfaces... 

In another study of protein structure, Cox and Johnston3 analyzed how the choice of GA parameters affects the quality of the GA search. This sort of approach was also adopted by Djurdjevic and Biggs,4 who presented a detailed study of how evolutionary algorithms can be used, in combination with a full atomistic protein ab initio model, for fold prediction and, like Cox and Johnston, considered the influence of the different values of parameters on the success of their protein folding calculations. 

It has been shown (, , 2.) that a membrane casting dope is a strongly structurlzed polymer solution, and that the morphology of the membrane surface layer can be correlated to the structure of the casting solution. The latter parameter affects the nature and details of the phase inversion process occuring in the upper part of the cast solution, in an incipient skin. Thus the solution structure is one of the factors responsible for the skin properties, and consequently for the performance of the ultimately formed asymmetric membrane. 

The main parameters affecting the adsorption process of a given molecule in solution involve its size, shape, polarity, and chemical structure. 

The most important chemical parameter affecting the deposition and subsequent mobility of radioactive aerosols, such as the nuclides 90Sr and 137Cs examined in this study, is their solubility in rainwater. If these aerosols are dissolved in precipitation, the main factor in their transport is the movement of the rainwater, not the transport of insoluble aerosol particles. Huff and Kruger (2) examined the solubility products of strontium and chemically similar compounds which may carry trace amounts of 90Sr, and they estimated that strontium should be soluble in precipitation. Solubility tables also indicate that cesium compounds likely to exist in precipitation should be soluble. It was noted that the possibility did exist that some of the fission product "Sr and 137Cs might be bound within the structure of insoluble natural aerosols or nuclear weapon debris. 

Thermal as well as oxidative dimers have also been isolated and characterized from pure fatty acid and TGs oxidized under simulated deep fat frying conditions. These model systems have been employed in order to simplify and control the various parameters affecting the thermal-oxidative reactions and to facilitate the structure elucidation of the decomposition products. 

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