Biomedical subjects
Publications and source records attributed to H Eyring.
The first-order and zero-order kinetics of heterogeneous reactions coupled with the diffusion process are studied. The differential equations of these reaction systems are solved for the cases in which the fluid is not stirred and the fluid is well stirred. It is shown that both the rate constants and the diffusion coefficient can be determined in various ways depending on the experimental conditions.
Early in the era of atomic energy the potential of plutonium as an industrial and an environmental hazard was recognized. Thus, the Laboratory for Radiobiology was established at this University 20 years ago to compare the effects of plutonium and radium in beagles. Sufficient data have now accrued for exacting analysis. Concurrently we have formulated the steady-state theory of mutation rates which provides the necessary formalism to assess the survival data from the (239)Pu and (226)Ra study. Although the principal biological end point for both nuclides is the osteosarcoma, the mechanisms of nonsurvival for the two nuclides appear to be different. The success of the theory in this case suggests that application to data on irradiation of more inbred and more outbred species would prove to be exceedingly valuable.
The statistical effect of internal irradiation on the survival of beagles is similar to that of aging, with the exception that death occurs earlier. Since biological processes are close to equilibrium most of the time, the above observation suggests that death ensues when the rate of insult has exceeded the rate of recovery to a sufficient extent that the reserves are depleted and the steady state can no longer be maintained. The steady-state theory of mutation rates is derived from first principles, and, through absolute rate theory, is completely general and is not limited to a specific kind of cellular alteration. However, the nature of the cellular alterations that lead to nonsurvival are considered. The young growing system is also considered in the context of this theory.
From the steady-state theory of mutation rates we have the probability, q, of the occurrence of a critical change at some site in a cell that leads to genetic alternation, and the probability, p = 1 - q, that the site either is not changed or that it has been repaired. In this paper the formal theory is extended to include survival of biological systems. Single and multiple mechanisms of nonsurvival, and multiple factors acting on a single mechanism, are considered. The number of sites that must be altered to lead to nonsurvival is examined and found to be greater than one. The effect of independent action on separate sets of sites, and the relationship between dose size and survival time are given.
The interaction of configurations, including all possible singly excited configurations, is incorporated into the calculation of oscillatory and rotatory intensities of simple nonplanar pi-electronic systems such as skewed butadiene and acrolein. The results are discussed in terms of the reliability of the (self-consistent field)-(linear combination of atomic orbitals)-(molecular orbital) wave functions employed.
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The circular dichroism data on 17 adenine nucleosides show that the 260- and 207-mmu absorption systems of the adenine chromophore each contain at least two electronic transitions. The CD maxima are commonly found at around 260, 220, and 200 mmu, and occasionally at 240 mmu. Solvent studies suggest that these CD bands arise from pi-pi(*) transitions. A weak absorption band that obeys the McConnell criteria of an n-pi(*) band is resolved at about 290 mmu in hydrocarbon solvents. This band exhibits very little rotatory power.
An improved iteration method for calculating the surface tension developed by Chang et al. is presented. To test it, the surface tensions of the following liquids are calculated: A, N(2), CH(4), PH(2), Br(2), C(6)H(6), HgCl(2), and TiCl(4).The calculated results show the present method is an improvement over that of Chang et al. In addition to the change in the energy of sublimation of a molecule in a surface layer, which Chang et al. considered, the less important but not negligible effects on the number of nearest neighbors, eta(i), and the characteristic temperature, theta(i), are now included. eta(i) is proportional to the effective local density, and theta(i) is proportional to the square root of the effective local density. The calculated values fit the experimental data somewhat more closely than those calculated by the original method of Chang et al.
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