Materials Literature
按标题、摘要、年份、主题和来源检索公开元数据。结果保留作者、摘要、分类与原始来源链接。
Abstract The polymerization of propylene oxide at 80°C. catalyzed by aluminium trimethyl has been studied kinetically, using a dilatometric method combined with a high‐vacuum technique to exclude adventitious water and oxygen. Both in bulk and in methylene chloride solution, the reaction is not stereospecific in the a…
Recent observations of the growth of quenched-in dislocation loops during annealing are discussed. A mechanism for the coalescence of loops is proposed. The mechanism depends on short-circuit diffusion around the periphery of prismatic dislocation loops. This mechanism is contrasted with the theory of loop coalescence…
In a previous paper, an attempt was made to reduce the theoretical coercive force by assuming that the magnetocrystalline anisotropy constant vanished in a certain region. A modification of this assumption was made in the present work, namely, the magnetocrystalline anisotropy was taken as zero in a part of the "imper…
Electron microscope studies of the tracks produced by fission fragments in thin films of UO2 have established a 100% detection efficiency for fission events in films 100 A or less in thickness. A background texture decreases the efficiency in thicker films. The tracks register in the films primarily as a result of a r…
Abstract The solid state polymerization of acrylamide and related monomers has been studied using the tools of electron spin resonance and optical microscopy. The data indicate that the reaction involves free radicals which do not terminate in the usual fashion. The reaction apparently involves a nucleation mechanism…
First order phase transitions were investigated for n-nonane, n-dodecane, n-tridecane, n-pentadecane, n-octadecane, and n-tetracosane, at pressures up to 10 kilobars and temperatures up to 135°C. By a modification of standard piezometric techniques, phase transition pressures, as well as the associated isothermal isob…
The electron microscope has been, used to examine point defect clusters produced in copper and aluminium foils bombarded with l·4 × 1017 alpha-particles cm−2. The foils were bombarded as a stack and, in copper, both those through which the alpha-particles had passed and that in which they came to rest appeared similar…
The characteristic electron energy loss spectra of the elements of the first group of transition metals, Ti to Cu, have been obtained using the reflection technique. In the spectrum of each metal one loss peak is identified as a plasma loss, and another, except in Ti and V, as a lowered plasma loss. Two other series o…
The increases of the magnetic susceptibilities with temperature for non-ferromagnetic transition metals are investigated by making use of the band picture. If the Fermi surface at the absolute zero of temperature is in the neighbourhood of a minimum of the electron state density, the susceptibility increases with temp…
A theory is developed about the molecular size distribution in a system of copolymers which are composed of two different kinds of monomer units and undergo random crosslinking when exposed to high-energy radiations. The radiation-induced change in the molecular size distribution is described by an integro-differentia…
In addition to the α solid solution of arsenic in copper, three intermediate phases exist in the copper/arsenic system. The ε phase, stable only below ca. 340 °C, has the hexagonal A3 [Formula: see text] structure with a = 2.588, c = 4.226 Å, and the approximate formula Cu 8 As. The compound Cu 3−x As with 0 ≤ x ≤0.3,…
Measurements have been made of the variations with temperature of the intensities of x-ray diffraction lines from silver and iron. For silver the measurements were in the range 286–1100°K, and the Debye-Waller temperature factor corresponded to a characteristic temperature of 197°K at 286°K. For iron the measurements…
The univariant equilibrium pressure‐temperature curve along which β‐MnO 2 , Mn 2 O 3 , and O 2 are stable together has been determined up to a Po 2 of 200 atmospheres with a trace of water as a catalyst. The analogous curve for the assemblage Mn 2 O 3 , Mn 3 O 4 , and O 2 has also been determined. In both cases the ex…
Studies of dislocations in elongated aluminum crystals by diffraction electron microscopy revealed narrow dislocation loops lying parallel to 〈112〉. These loops formed only behind screw dislocations, their long parts then having edge character. Four mechanisms have been proposed to account for the formation and stabil…
Infrared absorption spectra have been obtained in the 430 to 4000 cm—1 region for B3O3(OH)3, B310O3(OH)3, and B3O3(OD)3, as polycrystalline mulls and, in the case of B3O3(OH)3, as a single crystal section. A partial Raman spectrum has been obtained for B3O3(OH)3 in the polycrystalline form. The spectral data have been…
Abstract Poly(ethylene terephthalate) prepared or fabricated by melt processes is shown to contain about 1.5% of extractable, oligomeric material composed mainly of cyclic ethylene terephthalates which exist, at high temperatures, in equilibrium with the molten polymer. An ester interchange‐elimination reaction is pro…
Dislocations having a Burgers vector in the basal plane and lying in this plane, have been studied in graphite by the use of thin foil transmission electron microscopy. The dislocations are dissociated into ribbons consisting of two partials separated by a stacking fault. Specific models for these dislocations are pre…
Studies were made of the climb of dislocations in silicon crystals induced by the diffusion of gold in the temperature range from 1000°C to 1300°C. For some studies, dislocations were introduced into previously dislocation-free crystals by indentation at room temperature and deformation at about 900°C in order to pred…
The basic requirements of a garment in use and basic techniques in garment manufacture are briefly discussed. The relevant mechanical properties, of buckling, compression in the plane of the fabric and shearing are described and methods of measurement are indicated. It is argued that there are upper and lower limits t…
The method of Luttinger and Tisza for finding the rigorous minimum of a quadratic form subject to certain strong constraints is generalized. In the extended method, one still minimizes the quadratic form with respect to a single weak constraint, which however now contains adjustable parameters. In determining the grou…