Molecular environmental effects

MOLECULAR ENVIRONMENTAL EFFECTS ON THE PUCKERING OF THE PROLINE RING... 

In the first part of this report, we discuss a fundamental aspect of shear-induced conformational transition of the PAA resulting from the interchain association that was monitored using the AuO fluorescence probe. Further, we discuss the influence of molecular environment on PAA conformation in relation to the DR behavior of the PAA. In the second part, we discuss a particular molecular environmental effect of cationic surfactants on the interchain association of the PAA, in that the chain conformation is dictated by the extent of the surfactant binding and the surfactant structure. 

Saenger, W. Environmental Effects on Molecular Structure (ed. Pullman, B.), p. 265, Dordrechit-Holland, D. Reidel 1976... 

Dosimetry of the Museum Environment Environmental Effects on the Chemistry of Paintings. Oscar F. van den Brink, Molecular Aspects of Ageing in Painted Works of... 

These external fields can affect the physical properties and reactivity of the molecular systems. Such effects are especially important in ordered crystalline environments such as solid oxides and biological macromolecules [25-28]. These local electrostatic fields play an important role in catalytic functions and in governing the stabilization of many biomolecular systems [29-32]. These environmental effects cause dramatic changes in the reactivity, which can be different from the gas phase. 

The empirical valence bond (EVB) approach introduced by Warshel and co-workers is an effective way to incorporate environmental effects on breaking and making of chemical bonds in solution. It is based on parame-terizations of empirical interactions between reactant states, product states, and, where appropriate, a number of intermediate states. The interaction parameters, corresponding to off-diagonal matrix elements of the classical Hamiltonian, are calibrated by ab initio potential energy surfaces in solu-fion and relevant experimental data. This procedure significantly reduces the computational expenses of molecular level calculations in comparison to direct ab initio calculations. The EVB approach thus provides a powerful avenue for studying chemical reactions and proton transfer events in complex media, with a multitude of applications in catalysis, biochemistry, and PEMs. 

Van Beneden, R.J., Environmental effects and aquatic organisms investigations of molecular mechanisms of carcinogenesis, Em. Health Perspect., 105 (Suppl. 3), 669, 1997. 

Initial photooxidation and several other factors will diminish the molecular weight of polymers thereby releasing low molecular weight portions of pol3nneric chains which eventually can be biodegraded. The total environmental effect on polymers is therefore put together by... 

Table V. Effect of Structural and Molecular Environmental Factors...

In reporting the bandstructure calculations for DNA-based molecular wires, we first focus on the kind of information that may be extracted from the study of model nucleobase assemblies, and then analyze the attempts to treat realistic molecules. Finally, we give a brief account of the environmental effects, e.g., the presence of water molecules and counterions. 

Combining structure-activity relationship (SAR) analysis with an understanding of functional use for product components has provided a means to compare and begin to understand the importance of the relationship between functionality and environmental effects at the molecular level. At the core of functionality is molecular structure, which drives both performance and toxicity. In some cases, this insight helped drive the development of safer substitutes, whereas in others it brought out the inherent limitations in identifying safer alternatives based on currently available chemistries and technologies. 

Also, increase in water temperature favors -conformation. Inasmuch as the conformation of CP probably determines the tertiary structure of MM, slight changes in CP conformation introduced by cellular or environmental effects may alter MM conformation. This in turn is reflected in the mineral form and structural pattern of the inorganic phases. Perhaps, nacreous layers in molluscs represent an almost ideal situation where MM and CP are aligned in a symmetrical way. In fish otoliths, the fibrous organic matrix is a mixture of helices and 0-pleated sheets. It is tentatively concluded that the morphology of shell structures is a macroscopic expression of the molecular interactions between MM and CP which are controlled in part by cellular activities and in part by the environment. 

McKean 182> considered the matrix shifts and lattice contributions from a classical electrostatic point of view, using a multipole expansion of the electrostatic energy to represent the vibrating molecule and applied this to the XY4 molecules trapped in noble-gas matrices. Mann and Horrocks 183) discussed the environmental effects on the IR frequencies of polyatomic molecules, using the Buckingham potential 184>, and applied it to HCN in various liquid solvents. Decius, 8S) analyzed the problem of dipolar vibrational coupling in crystals composed of molecules or molecular ions, and applied the derived theory to anisotropic Bravais lattices the case of calcite (which introduces extra complications) is treated separately. Freedman, Shalom and Kimel, 86) discussed the problem of the rotation-translation levels of a tetrahedral molecule in an octahedral cell. 

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