Materials Literature
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The structure and mechanical properties of wool fibers and assemblies of wool fibers are explored. A progressive study of mechanics from the simple assemblies of fibers, as in wool staples and fiber bundles, through complex clothing structures made from fibers and fabrics shaped in three dimensions is developed. The i…
Plastic flow of polycrystalline solids at elevated temperatures occurs by one of three independent deformation mechanisms: slip by dislocation movement, sliding of adjacent grains along grain boundaries, and directional diffusional flow. All three mechenisms are considered to be thermally activated and controlled by t…
Introduction and General Survey. Measurement of Thermal Conductivity. Electrons and Holes in Semiconductors. Electronic Thermal Conductivity. Phonons and Phonon Scattering Processes. Lattice Thermal Conductivity. Semiconducting Materials--Analysis of Experimental Data I. Semiconducting Materials--Analysis of Experimen…
An algorithm for the protection of power transformers is described in which transformers are represented by a universal equivalent circuit composed of inverse inductance, without reference to an internal fault. The circuit is derived from multiterminal network analysis of the windings. The intrinsic characteristics of…
Abstract N,N′-Dialkyl-1,4-benzenedicarboxamides melt with anomalously small enthalpy changes. The 1,3-analogs behave similarly but at lower temperatures. These observations provide a clue to design novel mesomorphic compounds; N,N′,N″-trialkyl-1,3,5-benzenetricarboxamides. The compounds carrying pentyl to octadecyl gr…
Abstract Viscosity‐average relative molecular masses have been determined for a series of chitosans having the same relative molecular mass and relative molecular mass distribution but differing extents of N‐acetylation. The results obtained show that the same viscometric constants in the Mark‐Houwink equation [η] = K…
Chiral poly(thiophenes) have been synthesized by electropolymerization; they exhibit high specific rotation, stability, and conductivity and can stereoselectively recognize chiral anions used as doping agents during voltammetric cycles.
Abstract The frontrunner in the race to develop a high temperature resin for use in advanced composites intended for high temperature applications is the NASA developed polyimide PMR‐15. One of the key factors in the success of the material is the relatively easy processing which is due mainly to the use of the PMR ap…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTVariable antiferromagnetic exchange in a series of binuclear copper(II) complexes of tetradentate (N4) and hexadentate (N6) diazine ligands. Magnetism versus structure, bridging and terminal ligand groups, and chelate ring size. Crystal and molecular structure of [.mu.-1,4-b…
The presence of free metallic particles and some other conditions which might lead to breakdown in 420 kV gas insulated substations (GIS) can be detected by measuring their partial discharge activity. The discharge pulses excite the GIS chambers into many modes of resonance at ultra high frequency, which may be picked…
The constitutive law relating the time rate of change of the magnetic field H to that of the flux density B, via a differential equation, yields a faithful and yet computationally tractable representation of magnetic hysteresis. The equation is used to develop a theory of rate-independent and rate-dependent hysteresis…
The potential response behaviour of a chloride doped polypyrrole (PPy) polymer film electrode to chloride ion in solution has been examined. The effect of the polymerisation conditions on the characteristics of the potential response and response mechanism is discussed. A chloride ion-selective electrode based on a co…
A new criterion for parametric sensitivity or thermal runaway is proposed in the context of thermal explosions, which can also be readily utilized for chemical reactors. Criticality is defined as the situation where the normalized objective sensitivity, of the temperature maximum to any of the physicochemical paramete…
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Two sources of individual Auger electron spectra and an electron track code were used with a simple model of the DNA to successfully simulate the single-strand DNA breakage measured by Martin and Haseltine (1981). The conditions of the calculation were then extended to examine patterns of single-strand breaks in both…
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The lithium alkoxide-catalysed cyclic tetramerisation of various 3,6-dialkoxy-4,5-dichlorophthalonitriles, 1,4-dialkoxynaphthalene-2, 3-dicarbonitriles and 3,6-dialkoxyphthalonitriles to give the corresponding metal-free octa-alkoxyoctachlorophthalocyanines, octa-alkoxynaphthalocyanines and octa-alkoxyphthalocyanines…
Ultrafine and nearly spherical ferrites such as NiFe 2 O 4 , ZnFe 2 O 4 , Ni x Zn 1−x Fe 2 O 4 , Mn 0.5 Zn 0.5 Fe 2 O 4 , and CoFe 2 O 4 were prepared under mild hydrothermal conditions by precipitating from metal nitrates with aqueous ammonia. These hydrothermal ferrite powders were shown to sinter to almost theoreti…
The Taylor theory and the Bishop–Hill theory for the plastic deformation of polycrystals are expressed in a mathematical way which makes extensive use of vectors. These vectors represent either plastic strain rate tensors or deviatoric stress tensors, both in a unified five‐dimensional stress‐strain space. Such formul…
A numerical approach is described that overcomes the deficiencies of other methods through the use of a two-dimensional, nonlinear, time-stepping finite-element method for excitation from a constant voltage source. Comparison of stator current for no-load and load conditions shows good agreement with test values on a…