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Biomedical subjects

H Eyring

Publications and source records attributed to H Eyring.

At least 91 records · Page 5Linked to original sources
PubMed1972

Molecular orbital studies of ethylenediamine conformations.

Semiempirical quantum mechanical treatments are applied to the ethylenediamine di-cation, mono-action, and neutral molecule by the use of the extended Huckel theory.The minimum energies of conformations of molecules for rotation about the CH(2)-CH(2) axis is found. The theoretical predictions for the conformation with minimum values. The importance of the ethylenediamine conformations are discussed.

Journal Article↗
PubMed1972

Stochastic Model of Unimolecular Reactions and the RRKM Theory.

A stochastic model of unimolecular reactions has been adopted for investigation of the validity and limitation of the RRKM theory. The error caused by the steady-state approximation for distribution of energized molecules is small, while the assumption of the internal energy equilibration of energized molecules might cause serious errors for reactions of low activation energies.

Journal Article↗
PubMed1972

The dynamics of life: aging.

Biologic aging arises from various causes, including deterioration of cells by mutations, destruction of the cells in organs through infections, aging by failure to eliminate harmful waste products, poisoning from external sources, and by radiation damage. All of these processes lead to equations of the kind observed experimentally for the aging process, so that a proper assessment of the various factors contributing to aging is especially complicated. Many nonbiological processes in which the products of reaction speed up the aging reaction lead to the familiar equation for the rate of aging. Corrosion of metals is exhibited as a typical example of this; many other examples could be given. The general equation for depth of anesthesia brought about by lipid-soluble materials and how this effect can be mimicked by accumulation of waste products is shown to simulate the typical aging curve; it is well known that such waste products are a frequent cause of death.

Aging↗
PubMed1972

Significant structure theory of surface tension of the alkali metals.

The volume and temperature dependence of the solid-like structure in liquids has been properly taken into account in calculations of surface tension of the liquid alkali metals. The surface tension equation derived from the significant structure theory of liquids is used. The results are quite satisfactory when compared with observed values.

Journal Article↗
PubMed1972

Significant liquid-structure theory of viscosity and self-diffusion of the alkali metals.

Significant liquid-structure theory has been used to calculate the transport properties of the alkali metals. Unlike previous calculations, the volume and temperature dependence of the solid-like structure has been taken into consideration. Equations for the potential energy as a function of volume of the alkali metals, which lead to agreement between calculated and experimental values of thermodynamic and transport properties, are given. The calculated results are in satisfactory agreement with the experimental data.

Journal Article↗
PubMed1972

Physical adsorption of the quantum gas.

The significant structure theory of quantum liquids such as hydrogen, deuterium, and helium has been applied to the physical adsorption occurring in the submonolayer region. The partition function for the two-dimensional adsorbed fluid has been derived. The properties of isothermal and isosteric heat show good agreement with the available data from the literature.

Journal Article↗
PubMed1972

Magnetic circular dichroism of molecules in dense media: benzene.

This paper presents some calculated results on the vibrational structuring of the magnetic circular dichroism of the benzene (1)A(1g)"(1)B(2u) transition. The good agreement between the experimental and calculated relative intensities of the B-bands (positive magnetic circular dichroism bands) indicates that these bands are mainly induced by the e(2g) 1596 cm(-1) mode. The unfavorable results obtained by comparison of the theoretical results with experimental results for the A-bands (negative magnetic circular dichroism bands) is presumably due to neglect of the contribution from the e(2g) 3056 cm(-1) mode, from hot bands, and from the transitions of normal modes other than the A(1g) 992 cm(-1) mode. It should be noticed that while the e(2g) 608 cm(-1) mode plays a dominating role in the ultraviolet spectrum of benzene, in the magnetic circular dichroism of benzene, the e(2g) 1596 cm(-1) mode is, if not more important, at least as important as the e(2g) 608 cm(-1) mode.

Journal Article↗
PubMed1972

Hydrostatic pressure and ionic strength effects on the kinetics of lysozyme.

The kinetics of the reaction catalyzed by egg-white lysozyme from hen eggs (EC 3.2.1.17) was investigated by measurement of the decrease in turbidity of suspensions of dried Micrococcus luteus cells. The substrate and NaCl concentration were varied, as well as the hydrostatic pressure (1-476 atm). A plot of the initial velocity against the reciprocal of the substrate concentration gave straight lines. From these plots values for the maximum velocity, V, and the apparent Michaelis constant, K(m), as well as the effect of NaCl concentration were determined. The maximum velocity showed a pronounced maximum when plotted over a range of NaCl concentration from 0-0.208 M. The volume change of activation, DeltaV([unk]), calculated from V, was negative, and decreased in absolute value from -8 to about 0 cm(3)/mol as the NaCl molarity was increased over the above range. This effect is explained as due to a different number of salt molecules being built into activated complexes with each of these activated complexes reacting at its own characteristic rate. Strong pressure-dependence of enzyme catalysis indicates appreciable conformational changes of the enzyme as it is incorporated into the activated complex. The volume change causing the pressure effect arises principally from changes in the number of ionized species with the accompanying electrostriction.

Animals↗
PubMed1971

Solution of the time-dependent schrödinger equation by the laplace transform method.

The time-dependent Schrödinger equation for two quite general types of perturbation has been solved by introducing the Laplace transforms to eliminate the time variable. The resulting time-independent differential equation can then be solved by the perturbation method, the variation method, the variation-perturbation method, and other methods.

Journal Article↗
PubMed1971

The elastomeric rack in biology.

A model designated "The elastomeric rack" is discussed with reference to the mechanism of enzyme catalysis and the necessity of large protein molecules in the process. This model, which represents an extension of the earlier "Rack mechanism," stems from experimental evidence demonstrating large volume changes of activation or of reaction accompanying various biochemical reactions and more complicated physiological processes. For reasons discussed, the volume changes, as revealed through the influence of increased hydrostatic pressure on reaction rates and equilibria, prove that there are large conformational changes in the protein which, because of numerous cross links in a complex network, lead to additive stress on the substrate-enzyme complex, and thereby to increased reactivity. The manner in which the model serves to account for the influence of changes in the environment (temperature, pressure, chemical composition, electrical fields) on the activity of the protein catalyst, and the modifying action of particular inhibitory or activating substances, alone or in combination, is briefly discussed. The bearing of various considerations on protein denaturation, excitation of nerve, contraction of muscle, specific precipitation, and the divers physiological processes in living cells, including mutation, cancer, and the degenerative diseases of aging, is also briefly discussed.

Catalysis↗
PubMed1971

Calculation of the reaction cross section from a rate constant by the method of steepest-descent.

The reaction cross section of a bimolecular reaction has been calculated from the corresponding rate constant by the inverse Laplace transform. In carrying out the inverse Laplace transform, the method of steepest-descent has been used. As applications, the reaction cross sections for the rate constant of k(T) = k' T(n)e(-E0/kT) and for the rate constant of the absolute reaction rate theory have been calculated. The computation of the energy density function associated with the definition of the weighted-average cross section has also been discussed.

Journal Article↗
PubMed1971

Kinetics of heterogeneous chemical reactions: a theoretical model for the accumulation of pesticides in soil.

A theoretical model for the accumulation of pesticides in soil has been proposed and discussed from the viewpoint of heterogeneous reaction kinetics with a basic aim to understand the complex nature of soil processes relating to the environmental pollution. In the bulk of soil, the pesticide disappears by diffusion and a chemical reaction; the rate processes considered on the surface of soil are diffusion, chemical reaction, vaporization, and regular pesticide application. The differential equations involved have been solved analytically by the Laplace-transform method.

Chemical Phenomena↗
PubMed1971

The dynamics of life. V. Applying the steady-state theory of mutations to human cancer.

In papers I, II, and III of this series the steady-state theory of mutations was developed and applied to the extensive data on the effect of radiation on beagles acquired here during the past twenty years. In this paper the theory is used to interpret H. B. Dorn's data on the incidence of 21 kinds of cancer in both male and female Americans. The theory shows the nature of the heterogeneity in the population of various disorders. The agreement found confirms the steady-state theory of mutations in an interesting way.

Age Factors↗