Materials Literature
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A number of esters and other compounds containing a trans-1,4-substituted cyclohexane ring system-have been prepared, and the liquid crystal thermal stabilities of these new mesogens are discussed in relation to those of their analogues containing the 1,4-phenylene ring. The observed effects are discussed in terms of…
[Au9L8]3+(L = PPh3) reacts with L to form [Au8L8]2+ and [AuL2]+; preliminary X-ray structural results are reported for [Au8L8][PF6]2.2CH2Cl2(1).
The reduction of aromatic nitro-compounds by NaBH4 in ethanol in the presence of various transition metal cetylacetonates has been investigated. Copper(II) acetylacetonate was found to be the most effective catalyst for reduction to the corresponding amines. This reaction appears to proceed through a hydride metal com…
The abrasive wear resistance and fracture toughness of the principal types of alloy white cast iron have been determined in laboratory tests. It was found that low-stress abrasion resistance is controlled principally by the hard, dispersed carbide phase, and that the hardness of the matrix is of secondary importance o…
The effect of ordering on the magnetic properties such as magnetostriction, magnetic anisotropy, permeability, and coercive force of 6.5-percent silicon-iron alloy has been studied. The alloys were heat-treated at various temperature, and then quenched into oil. It was found that magnetostriction decreases with the gr…
Massive wound edema after a burn may impair healing and help to convert partial to full-thickness injury. Cold treatment (usually by immersion) has been reported to decrease wound edema and is useful in first-aid treatment of burns. Reliable quantitative data have been lacking and frequently a superficial burn has bee…
The effects of deformation on the structure of copper and its low stacking-fault energy alloys are reviewed and it is shown that these may be classified according to the method of examination used. In rolled low stacking-fault energy alloys the deformation sequence involves the formation of stacking faults, mechanical…
The possibility of large scale mobility of flexible linear macromolecules is discussed with examples of quantitative studies of crystallization and melting kinetics, the segregation of complete molecules on crystallization and the direct observation of molecular diffusion.
Abstract Detailed results of the overall thermal degradation of poly(butylene terephthalate) are reported. Laser microprobe analysis and dynamic mass spectrometric techniques were used to identify the primary volatile degradation products and initial pyrolysis reactions that control polymer degradation. A complex mult…
Reaction of tetrasodium tetrathiafulvalene-tetrathiolate with transition metal salts leads to the formation of tetrathiafulvalene-metal bisdithiolene oligomers which in the case of the nickel derivative possesses unusually high conductivity (ca. 30 Ω–1 cm–1).
A. Keller, Faraday Discuss. Chem. Soc., 1979, 68, 145 DOI: 10.1039/DC9796800145
Zinc tetraphenylporphine shows fairly weak fluorescence and phosphorescence but intense, long-lived triplet absorption. Benzo-1,4-quinone quenches the singlet and triplet excited states of ZnTPP and the quenching probability increases with increased polarity of the solvent. Quenching leads to formation of a complex wh…
Some of the earliest investigations concluded that the basic mechanisms of fatigue in composites and fatigue in homogeneous materials differ greatly. Instead of the initiation and propagation of a fatigue crack traditionally identified with homogeneous materials, fatigue in composites consists of various combinations…
Vibrational spectra of α-P2W18O62 6− and of the two isomers α1 and α2-P2W17O61 10− are reported and discussed by comparison with those of PW12O40 3−. With given assumptions, calculations of force constants for the PO4tetrahedra are carried out. The location of the holes in the structures of α1 and α2-P2W17 are inferre…
In this paper, the Rayleigh hypothesis in the theory of reflection by a grating is investigated analytically. Conditions are derived under which the Rayleigh hypothesis is rigorously valid. A procedure is presented that enables the validity of the Rayleigh hypothesis to be checked for a grating whose profile can be de…
The crystal and molecular structures of the β-polymorphic forms of phthalocyaninatomanganese(II), [Mn(pc)], and phthalocyaninatocobalt(II), [Co(pc)], have been determined by single-crystal X-ray diffraction methods at 295 K, and also at 116 K in the case of [Mn(pc)]. Crystals are of the monoclinic β-polymorph type, sp…
Rates of relaxation of polymer chains of high molecular weight preclude extensive configurational rearrangements of long range in the process of crystallization from a melt. Analyses of neutron scattering functions for deuterated polyethylene and polypropylene chains dispersed with the corresponding protonated host in…
The principles of forming metastable solids by rapid melt quenching are reviewed with primary emphasis on the growth of crystals into melts and glasses. Experience is reviewed which indicates that the rate of growth of crystals in pure metal melts may be limited only by the impingement frequency of atoms from the melt…
Examines the evolution of this new scientific discipline. Deals with selected solid (engineering) materials while also describing asbestos, asphalt, natural gas, cellulose, wood, reeds, lignin, paper, liquid crystals, spinels, coal tar, and coal gas and petroleum. Considers such recent materials as glassy metals, sial…
A promising alternative for hydrogen storage is storage as a metal hydride. The properties and applications of those systems which have proven or potential utility as hydrogen storage compounds are summarized. Specific systems discussed are magnesium alloy hydrides, iron-titanium alloys, titanium-chromium alloys, and…