Materials Literature
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A new choice of unit layer proposed by Sadanaga & Takeda (1968) has been found useful for explaining the two characteristic features of the X-ray diffraction pattern of the mica, namely, the periodic intensity distribution and the partial enhancement of symmetry. The recognition of the fact that the symmetry of the ne…
Cotton cellulose has been subjected to swelling and stretching treatments under various conditions. It has been found that the cellulose I lattice is highly resistant to alkali attack and difficult to disrupt completely during a single swelling treatment. The residual cellulose 1 “nuclei” grow upon stretching the swol…
Tensile tests on a Mg–0·8% Al alloy have been conducted at a strain rate of 10−2h−1 between 25 and 400° C with grain sizes ranging from 0·009 to 0·300 in. It is shown that the growth of voids occurs by a grain-boundary sliding mechanism and the variation of ductility in the intergranular-failure range is interpreted b…
Oxidation of mixtures of a p-phenylenediamine and a m-phenylenediamine is shown to give aminoindamine dyes by a reaction between the p-benzoquinonedi-imine and the m-diamine. At pH > 7 the latter reaction involves electrophilic attack by the conjugate acid of the di-imine on the electron-rich carbon [C(4)] of the m-di…
The unsensitized thermal decomposition of the vapour of diallyl oxalate has been studied in a fused quartz cell between 130 and 190°C. The products are consistent with the formation of allyl radicals in the primary dissociation: (COOC3H5)2→ 2CO2+ 2C3H5·; k1= 1014 ± 1 exp(–40 ± 3) 103/RT sec–1 This system is well suite…
The preparation of a number of novel aromatic macrocycles related to porphins, but containing furan and thiophen rings in addition to pyrrole rings, is described, together with deuterium exchange studies on some of the macrocycles.
The dissolution processes involved in the formation of porous films in sulfuric acid have been studied by suddenly lowering the formation voltage and observing changes in the current flowing and the barrier layer capacitance as steady‐state conditions are re‐established. It was found that current changes always follow…
The types of systems available are briefly mentioned, together with the mechanisms involved in the photochromic changes. The behaviour of the materials under irradiation, both for activation (colouring) and reversal (erasure), the effect of temperature, and reversibility and resolution are discussed. The optimum perfo…
The complete oxidation of methane over zeolites containing palladium, platinum, rhodium and iridium has been studied using a microcalorimetric technique. The results show that isolated ions of these metals are able to adsorb both methane and oxygen but only with platinum do methane and oxygen adsorb competitively. The…
As composites are a combination of many organic and inorganic materials already studied, we draw on this information to guide us in strength evaluations, interpretation of results, and design aspects of the new materials. Basically, many micro- and macrostructural differences exist between the materials made of metals…
Abstract In the catalyzed polycondensation reaction of poly(ethylene terephthalate), defined by equation image rates of polymerization in thin films under vacuum are orders of magnitude greater than those observed in an equilibrating system. Such behavior is consistent with a mechanism in which a volatile component of…
Abstract The stress‐strain‐optical properties of three elastomeric styrene‐butadiene block copolymers containing 31, 40, and 49 wt‐% styrene were studied as a function of temperature. The mechanical and the optical properties indicate that these materials are two‐phase systems in which the polybutadiene chains form an…
Abstract not Available.
An experimental study has been carried out to investigate the effect of growth variables on dendrite morphology and dendrite arm spacing in 25Cr-20Ni stainless steel and 1Cr-0.25Mo steel, solidified vertically under semi-steady state conditions.The condition for cell formation and the cell to dendrite transition has b…
ZusammenfassungBevor man Wechselwirkungen zwischen Elektronen und Lichtquanten diskutieren kann, sind zunächst die beiden Einzelsysteme zu untersuchen. Die Quantentheorie der Einelektronensysteme wurde bereits behandelt, damit muß man sich nun der Quantentheorie der Strahlung zuwenden. Dazu sind lediglich die bisher e…
The gas-phase Raman spectra of P4, As4, P2, and As2 are recorded and compared with literature values for P2 and As2 derived from electronic spectroscopy, and for sulphur, the gas-phase Raman spectra of S8 and S6 are obtained, together with a polarized band at 237 cm.–1 which is probably due to S7.
Abstract The piezoelectric constants e 11 and e 14 of tellurium have been found by measurement to be 0.42 C m −2 and 0.17 C m −2 . They are described by strain‐induced displacement of the electron distribution relative to the Te cores.
On précise les structures magnétiques des sous-réseaux de fer et de terre rare dans quelques orthoferrites de terres rares. L'hypothèse d'une très forte anisotropie de la terre rare permet d'interpréter la polarisation non colinéaire du sous-réseau de terre rare dans l'état paramagnétique par le champ dû à l'ordre du…
Abstract A careful analysis of certain observations concerning the polaron nature of current carriers in rutile is presented. The criticism of our paper [1] given in [2] is shown to be unfounded.
The equilibrium positions of all the partial dislocations in a pile-up of dissociated dislocations are calculated numerically. As expected, the equilibrium width of the stacking fault varies along the length of the pile-up-being smaller near the tip than farther away from the tip. However, the stress concentration at…