Materials Literature
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Abstract Fine structures of several plastic/rubber two ‐phase polymer systems were studied by means of direct observations of ultrathin sections under the electron microscope using osmium tetroxide staining and a hardening procedure developed recently by Kato. Samples used are several types of both ABS polymers and hi…
Abstract Synopsis The diffusion of six solvents in three crosslinked, glassy epoxy polymers is studied. Case II swelling and Fickian sorption are observed as two simple limiting cases. The mechanism of diffusion changes from one limit to another as the nature of the solvent or the crosslink density of the polymer is a…
Summary The main advantage of high voltage in electron microscopy is greater penetration. When using an aperture of optimum size the thickness of specimen that can be imaged increases almost linearly with applied voltage in the case of light elements, both when the criterion is image intensity and when it is resolutio…
The dislocation sub-structure and surface markings formed during the early stages of fatigue in copper single crystals at room temperature were studied. For the first few cycles the structure is similar to that associated with stage I of tensile deformation. A three-dimensional network of interconnected veins packed t…
Abstract Weathering products formed on surfaces of both potassium and plagioclase feldspar (An 70 ), which were continuously leached in a Soxhlet extraction apparatus for 140 days with 7·21 of distilled water per day at a temperature of approximately 78°C, are morphologically identical to natural products developed on…
A relatively simple thin-film structure using vanadium dioxide is analyzed in detail to show that high-temperature, low-resistivity filaments can exist in VO2under appropriate electrical bias. These filaments will dominate both the static and dynamic electrical behavior of the structure, giving rise to V-I characteris…
An analysis of electron energy loss spectra of some 12 transition metal dichalcogenides has given useful information towards the understanding of the band structures of these layer-type solids. Using the experience gained from studying graphite in which the valence band consists of two groups, namely π and σ bands, a…
An investigation of the effects of small additions of Fe 2 O 3 to lead zirconate‐lead titanate ceramics with compositions between 45 and 60 mol% lead zirconate has shown that, with 2 moles of PbO to balance each mole of Fe 2 O 3 , the solubility of Fe 2 O 3 was about 0.8 wt% in compositions near the tetragonal‐rhomboh…
Element abundance distribution, systematic compositional variations, environmental and genetic factors, diagenesis (recrystallization to low-Mg calcite)
Abstract Dynamic mechanical properties determined with a torsion pendulum were used to ascertain the glass transition temperature T g of poly‐ε‐caprolactone. By measurements on compatible blends of poly‐ε‐caprolactone and poly(vinyl chloride), the T g of amorphous poly‐ε‐caprolactone was shown to be 202°K at about 1 c…
Abstract Cysteine synthetase in Salmonella typhimurium is a multifunctional protein complex of molecular weight 309,000 which catalyzes the two-step synthesis of l-cysteine from l-serine, acetyl-CoA, and sulfide. Certain enzymic and chemical properties of a purified preparation of cysteine synthetase have been studied…
An experimental study is described of the formation and growth of gas bubbles in crosslinked elastomers. A critical condition for bubble formation is found to hold in most cases: The gas supersaturation pressure must exceed 5G/2, where G is the shear modulus of the elastomer. The kinetics of bubble growth are shown to…
An empirical equation is developed for the prediction of total penetration distance of a projectile in many natural earth targets. Development of this equation was based on approximately 160 full-scale penetration tests into a variety of targets, including rock, gypsite, permafrost, ice, desert alluvium, silt, sand an…
The geometry of the deformation produced by the climb of edge dislocations is defined and the conditions are determined under which dislocation climb, by itself or in conjunction with glide, can produce a general change of shape. The results are important in understanding the high-temperature deformation (T > 0.5Tm) o…
The contribution to the electrical resistivity caused by grain boundaries has been measured in polycrystalline specimens of high purity copper and various grades of high purity aluminium. The specific grain boundary resistivity appeared to be independent of the impurity content, depended to a small extent on the tempe…
Using mass spectroscopic and ultrahigh vacuum techniques, solution and diffusion of hydrogen in tungsten was investigated for pressures between 600 and 10−8 Torr and temperatures between 1100 and 2400 K. Solubility and diffusion constants are derived from degassing rates of a solid cylinder which was pre-loaded with h…
A simple phenomenological constitutive equation for porous materials is proposed, which allows a detailed description of irreversible compaction behavior at low pressures and reduces to the correct Hugoniot description at high pressures. The theory is compared to some existing data on Hugoniots of porous aluminum and…
The transition metal dichalcogenides are about 60 in number. Two-thirds of these assume layer structures. Crystals of such materials can be cleaved down to less than 1000 Å and are then transparent in the region of direct band-to-band transitions. The transmission spectra of the family have been correlated group by gr…
The most recent achievements in the study of the degradation and the stabilsation of polyorganosiloxanes, including those containing other atoms in the chain, are surveyed. The effect of polymer structure on their thermal stability is examined, and the part played by catalytic impurities in developing processes of the…
The structure and the chemical properties of polymeric radicals having their free valency on a carbon atom in the main chain are surveyed. Most of the information on radicals in solid polymers has been obtained by electron spin resonance. The first part of the review gives a detailed analysis of the hyperfine structur…