نتایج جستجو برای: activation enthalpy
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Diffusion experiments with indium In in germanium Ge were performed in the temperature range between 550 and 900 °C. Intrinsic and extrinsic doping levels were achieved by utilizing various implantation doses. Indium concentration profiles were recorded by means of secondary ion mass spectrometry and spreading resistance profiling. The observed concentration independent diffusion profiles are a...
Acid catalysis by hydronium ions is ubiquitous in aqueous-phase organic reactions. Here we show that hydronium ion catalysis, exemplified by intramolecular dehydration of cyclohexanol, is markedly influenced by steric constraints, yielding turnover rates that increase by up to two orders of magnitude in tight confines relative to an aqueous solution of a Brønsted acid. The higher activities in ...
The pressure–composition (PC) behavior of deuterium in single crystal Pd has been measured over a temperature range extending from room temperature to 393 K. These data allow the determination of (i) relative partial molar enthalpy and entropy, without the contribution of the configuration entropy, for the dilute solid solution phase, (ii) enthalpy and entropy change characterizing the a→a9 pha...
In Escherichia coli, the behavior of the flagellar rotary motor near zero load can be studied by scattering light from nanogold spheres attached to proximal hooks of cells lacking flagellar filaments. We used this method to monitor changes in speed when cells were subjected to changes in temperature or shifted from a medium made with H(2)O to one made with D(2)O. In H(2)O, the speed increased w...
Time and temperature dependence of the binding of 3H-dihydroalprenolol (3H-DHA) to beta-adrenergic receptors in rat cerebral cortex is described. The kinetic data obtained suggest that 3H-DHA binding proceeds through a two-step reaction scheme consisting of a bimolecular association step followed by an unimolecular internal conversion of the radioligand receptor complex (isomerisation). Equilib...
The stereoselectivity of reaction of methyl acrylate, methyl methacrylate and methyl transcrotonate with cyclopentadiene was studied with ab initio RHF/6-31G* and B3LYP/6-31G* levels of theory. The stereoselectivities predicted for methyl acrylate and methyl methacrylate with cyclopentadiene in the gas phase were found to be in good agreement with experimental results. The preference of endo se...
Low-temperature high-stress rheology of olivine was investigated under water-saturated conditions by large strain shear deformation experiments using the Griggs-type apparatus. Samples at T=1273–1373K and P=2GPa under water-saturated conditions deformed under a significantly lower applied stress than expected from the power-law relation and the strain rate increases more rapidly with stress. Th...
The 2-D Cluster Variation Method: Topography Illustrations and Their Enthalpy Parameter Correlations
One of the biggest challenges in characterizing 2-D image topographies is finding a low-dimensional parameter set that can succinctly describe, not so much patterns themselves, but nature these patterns. The cluster variation method (CVM), introduced by Kikuchi 1951, characterize very local pattern distributions using configuration variables, identifying nearest-neighbor, next-nearest-neighbor,...
The corrosion of mild steel is a problem in industrial processes based on its deterioration exposure to acids, alkalis, and salt solutions. This issue has prompted an increase research interest order mitigate the harmful effects metals their alloys. thermodynamic adsorption analysis 0.5M hydrochloric acid solutions via ethanol leaf extract Phyllanthus mellerianus was investigated using w...
Because water dissolves in silicate melts as at least two species, H O molecules and OH groups, the exsolution 2 Ž . evaporation enthalpy of the H O component from a silicate melt depends on species proportions, which in turn depends on 2 H O pressure. In this short communication, a formal analysis of the exsolution enthalpy of water from a silicate melt is 2 presented, taking into account of t...
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