Materials Literature
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Experiments are reported which show that the temperature distribution in molten gallium contained in a horizontal boat on which is impressed an axial temperature gradient becomes oscillatory when the temperature gradient exceeds a critical value. It is proposed that the oscillations are an example of the phenomenon of…
Proceedings of the National Academy of Sciences (PNAS), a peer reviewed journal of the National Academy of Sciences (NAS) - an authoritative source of high-impact, original research that broadly spans the biological, physical, and social sciences.
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTThe Reaction between Bovine Brain Tissue Factor and Factors VII and X*Yale NemersonCite this: Biochemistry 1966, 5, 2, 601–608Publication Date (Print):February 1, 1966Publication History Published online1 May 2002Published inissue 1 February 1966https://pubs.acs.org/doi/10.1…
The temperature and stress dependence of the secondary creep rate of fine-grained polycrystalline magnesium have been investigated in the strainrate range 3·3 × 10−1 to 3·3 × 10−3 sec−1. Stress relaxation studies were combined with the creep experiments to obtain accurate values for the activation volume. They also ga…
A series of two-dimensional classical kinematic computer calculations have been made on the hypothetical exothermic exchange reaction A+BC→AB+C, −ΔH=48.5 kcal mole−1. Product energy distribution (vibration, rotation, and translation; Evib, Erot, Etrans) was obtained as a function of initial position, impact parameter,…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTThe Magnetic Susceptibilities of the Cobalt-Sulfur SystemRobert F. Heidelberg, Alan H. Luxem, Sami Talhouk, and John J. BanewiczCite this: Inorg. Chem. 1966, 5, 2, 194–197Publication Date (Print):February 1, 1966Publication History Published online1 May 2002Published inissue…
Abstract Changes in the molecular weight distribution of natural rubber, after mill mastication, have been studied by using a Water's gel permeation chromatography. This study indicates that as the polymer is milled the distribution is narrowed primarily through the breaking down of large molecular weight molecules. T…
The diffusion of hydrogen in copper-palladium alloys has been studied by utilizing the dependence of electrical resistivity upon hydrogen concentration—a technique both rapid and simple. At 25°C the diffusion coefficient in the range 0–58 at.% Cu is relatively insensitive to alloy composition but is extremely sensitiv…
Abstract Stress softening (Mullins effect) occurs in rubber vulcanizates during the first and subsequent deformations. This paper shows the similarity of the degree of stress softening in both unfilled and carbon black‐filled vulcanizates of natural rubber when stressed almost to break. This confirms the earlier inves…
The vertical migration of two Euglena species and several diatom species into and out of the sediment on the banks of the River Avon has been studied under natural conditions. All species have been shown to migrate vertically upwards when exposed during daylight. Tidal flooding of the sediment is generally preceded by…
Voltage-current curves of such organic insulators as polyethylene-terephthalate and polyvinylformal display the familiar Richardson-Schottky characteristics for fields between 20 and 200 kV/cm and temperatures from 25° to 100°C. Assuming the Schottky emission mechanism being the limiting factor in establishing the ste…
A fracture theory is proposed for a composite system based on a continuous glass matrix. It is hypothesized that hard crystalline dispersions within the glass matrix will limit the size of Griffith flaws and strengthen the composite. Quantitative relations are derived for the effect of a dispersed phase on composite s…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTSeparation of Gaseous Mixtures Using Porous Polyaromatic Polymer Beads.O. L. HollisCite this: Anal. Chem. 1966, 38, 2, 309–316Publication Date (Print):February 1, 1966Publication History Published online1 May 2002Published inissue 1 February 1966https://pubs.acs.org/doi/10.1…
A method is described for determining the optical constants of a thin film deposited on a nonabsorbing window using a single set of transmittances over an absorption band. The method depends on the fact that the phase shift of the transmitted radiation can be determined from the transmittances by a Kramers–Kronig tran…
Abstract Stress softening of carbon black‐reinforced butadiene‐styrene rubber was studied as a function of the rate and temperature of the original tensile deformation. To a good approximation, stress softening depends on the product of the extension rate and a temperature function which is analytically well represent…
<div class="htmlview paragraph">This paper describes full-scale engine studies conducted to determine the feasibility and compatability of ammonia combustion in various systems. Briefly outlined is the spark-ignition investigation undertaken by the Army Laboratory to learn the potential and effect of ammonia as…
Iron and aluminum were determined in acid ammonium oxalate extracts and in dithionite–citrate–bicarbonate extracts of a wide range of Canadian soils, several oxide and silicate minerals, and some amorphous preparations of iron or aluminum and silica. The oxalate extraction dissolved much of the iron and aluminum from…
The absorption and emission spectra of thallium in fused silica, aluminoborate, and phosphate glasses are similar to those of thallium-doped alkali halides and solutions. The absorption and emission bands in the different systems can be attributed to transitions within the central Tl+ ion in a center with a (TlXn)(n−1…
Investigation into the problem of melting within the earth strongly indicates that melting has taken place within the outer layers of the earth at some time in the earth's history. Fluid convection should then have occurred and have been an efficient method of heat transfer. Numerical methods are developed for calcula…
The magnetic properties of terbium oxide phases (Tb2O3 cubic and monoclinic polymorphs, TbO1.715, TbO1.809, TbO1.823, and TbO2) have been measured between 1.4° and 300°K. With the exception of TbO1.809, each of these phases is observed to order magnetically at low temperatures. The ordering is predominantly antiferrom…