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The kinetics of oxidation of Zircaloy‐4 in steam were examined under isothermal conditions from 900° to 1500°C. Rate curves describing the growth of the reaction product layers, oxide‐ and oxygen‐stabilized alpha, were obtained at 50°C intervals under carefully defined and documented experimental conditions. The early…
Abstract During the past several years the fundamental knowledge of the processes which lead to rubber-brass bond formation and to bond degradation has increased considerably. As a result of the application of new instrumental techniques to the study of the rubber-brass interface it has been established that the brass…
A previous paper demonstrated that the orientational disorder present in all smectic A phases causes most molecules to make fairly large angles with the normal to the smectic plane. Thus, the molecular directions form a diffuse cone around the layer normal. It is now argued that even the preferred directions of the mo…
Abstract A variable‐range hopping model is examined for transport in a band tail. For an exponential density of states the difference of the activation energies of conductivity and thermoelectric power, Δ E , is essentially determined by the steepness of the tail. Δ E varies slowly with tempera ture and depends little…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTStudies of supported nickel catalysts by x-ray photoelectron and ion scattering spectroscopiesMilton. Wu and David M. HerculesCite this: J. Phys. Chem. 1979, 83, 15, 2003–2008Publication Date (Print):July 1, 1979Publication History Published online1 May 2002Published inissue…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSubstituent effects in the electroreduction of porphyrins and metalloporphyrinsA. Giraudeau, H. J. Callot, Joseph Jordan, I. Ezhar, and Maurice GrossCite this: J. Am. Chem. Soc. 1979, 101, 14, 3857–3862Publication Date (Print):July 1, 1979Publication History Published online…
A Brownian dynamics model for the backbone chain of a macromolecule is developed as a system of linked rigid bodies so that constraints on valence angles and bond lengths are satisfied exactly. For comparison, a corresponding flexible model is developed in which bond lengths and valence angles are held nearly constant…
Zinc oxide films were produced by spray pyrolysis starting with aqueous solutions of ZnCl2, ZnCl2 plus H2O2, and Zn acetate, and structural, optical, electrical, and thermoelectrical properties of the deposited films were investigated. Highly transparent films with resistivity as low as 10−3 Ω cm can be produced by su…
The aim of this paper is to present the state of the art of the research on the physics of long sparks. The reference configuration is a non uniform long gap subjected to positive impulse voltages, which is the laboratory schematization of the most critical conditions occurring in the design of EHV apparatus. Under th…
Abstract A multiordering parameter model for glass‐transition phenomena has been developed on the basis of nonequilibrium thermodynamics. In this treatment the state of the glass is determined by the values of N ordering parameters in addition to T and P ; the departure from equilibrium is partitioned among the variou…
Abstract Using as bases the amount of clothing needed to achieve thermal comfort and the reduction in the skin's resistance needed to obtain thermal equilibrium, the relative sultriness of warm-humid and hot-arid summer climates is assessed. Conditions of equal sultriness are referred to a vapor pressure of 1.6 kPa in…
Abstract Die aus Tl(OCOCH 3 ) 3 ‐ n (N 3 ) n und einfachen, flexiblen Olefinen 1a‐1c erhaltenen 1‐Aziridinyl‐azothallium‐Verbindungen 2a‐2c liefern mit Säurehalogeniden oder Hexafluoressigsäureanhydrid in Lösung die entsprechenden trans ‐1‐Azido‐2‐halogencyclohexane 3f und 3g sowie trans ‐2‐Azidocyclohexyl‐trifluorace…
Enriched Fe 2 MoO 4 spinel was studied by Mossbauer spectroscopy in the temperature interval of 77-732K. The electrical conductivity measurements were carried out in the temperature range 298-475K. From these studies, it was concluded that fast electron exchange takes place amongst Fe 3+ and Fe 2+ ions situated at A a…
The first observation of photoluminescence (PL) originating from intrinsic defects in annealed and neutron-irradiated amorphous ($a\ensuremath{-}$)Si${\mathrm{O}}_{2}$ is reported. The PL is compared with that for $a$-${\mathrm{As}}_{2}$${\mathrm{S}}_{3}$. The PL spectra scale with energy band gap and the temperature…
We present preliminary results on the self-diffusion coefficient ${D}_{\mathrm{self}}$ of polystyrene chains (molecular weight ${M}_{n}=245000 \mathrm{and} 123000$) in benzene, obtained by forced Rayleigh scattering. In the semidilute regime where the chains overlap, ${D}_{\mathrm{self}}$ decreases with the polymer co…
We present a theoretical study of soliton formation in long-chain polyenes, including the energy of formation, length, mass, and activation energy for motion. The results provide an explanation of the mobile neutral defect observed in undoped ${(\mathrm{CH})}_{x}$. Since the soliton formation energy is less than that…
The diffusion coefficients D of vanadium in Fe–V solid solutions in the concentration interval 0 to 90 wt% V and in the temperature range 839 to 1320 °C are determined by the residual activity method using the isotope V-48. The measured residual activity values are evaluated by the least squares method on a ZPA-600 co…
The thermally stimulated current (TSC) has been used over a wide range of pressure to determine the principal characteristics of the polymers such as the activation volume ΔV, the activation energy ΔE, and the preexponential term τ0 of the Arrhenius-type relaxation time: τ=τ0 exp[(PΔV+ΔE)/kT]. Experimentally, the 6-Po…
The Monchick, Yun, and Mason generalization of the Wang Chang–Uhlenbeck–deBoer formulation of kinetic theory is the starting point for the generalized phase shift (GPS) evaluation of the transport coefficients. It is shown that the expressions for these properties can be written in terms of the rotational energy momen…
Abstract Polyimide fibers were prepared by wet spinning of poly( p , p ′ ‐diaminodiphenylmethanepyro‐mellitamic acid). Density measurements and x‐ray diffraction studies were carried out to study the structure of the resultant polyimide fibers. Polyamic acid as well as undrawn polyimide fibers were essentially amorpho…