Materials Literature
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All types of polygranular carbon and graphite materials take advantage of the extremely high strength of sigma -bonds in elemental carbon. Manufacturing processes have been developed during the last century which allow the control and distribution of domains with anisotropic microstructure within the bulk material. Su…
The authors argue that the McCurdy-Rescigno (1978) and Moiseyev-Corcoran (1979) methods used to calculate molecular resonances can be viewed as finite-matrix approximations to the mathematically precise 'exterior coplex scaling' method of Simon (1978).
Abstract Some impact tests are described in which Gc, the fracture toughness, of three polymers was determined over a range of strain rates and temperatures. It was found that at high strain rates there was a substantial variation of Gc with rate. When this was investigated as a function of loading times, it was obs…
Many commercially important catalysts consist of small metal particles dispersed on inorganic oxide surfaces. Although in most cases there is no significant interaction between the metal and the support, strong bonding can be demonstrated in a recently discovered class of supported-metal catalysts. These cases typical…
The decade of the ’80s was ushered in with a new dimension for designers, the availability of, and the meteoric cost increases of key materials. Though cost consciousness has always been a materials selection factor, current rates of increase make selection decisions more critical. Shortages of key metals such as coba…
A half century ago, researchers described foams as disperse structures that contain a colloidal liquid, such as a protein solution, as the dispersion medium and a gas or air as the disperse phase ( 1, 2, 3, 4 ). The factors principally involved in foam formation were surface tension, viscosity, and the character of th…
Abstract The evolution of the diatoms has never been considered in any detail and this paper sets out some of the problems and discusses briefly the fossil evidence, the likelihood of monophyletic versus polyphyletic origin and the possible habitats of the ancestral forms. We assume that diatoms arose at a fairly earl…
A microscopic calculation of localized electron states of an intrinsic, real, threedimensional disordered solid has been attempted by applying a first-principles method to a structurally relaxed large network of amorphous silicon dioxide. A valence-band mobility edge of 0.15-0.30 eV is estimated. No localized states a…
Robert L Fleischer et al 1980 London: University of California Press xxii + 605 pp price £9 (paperback) Some books, by virtue of their scope and timeliness, and the authority of their authors, quickly become the definitive texts upon their subject. This book is an example.
Abstract Mg(OH)2 powder packed into a basket was placed apart from solid SiO2 in an autoclave so that the SiO2 might react with the solid Mg(OH)2 in the state of soluble silica. At given temperatures of 250–360 °C, the Mg(OH)2 changed into talc(Mg3Si4O10(OH)2) through serpentine(Mg3Si2O5(OH)4): the reaction was a firs…
Abstract A comparative study was undertaken of the cationic oligomerization/polymerization of the natural propenylbenzene derivatives, anethole, isoeugenol, and isosafrole, together with synthetic o ‐methoxypropenylbenzene and N , N ‐dimethyl‐ p ‐propenylaniline using boron trifluoride diethyletherate as catalyst. Two…
A systematic classification of phase transitions corresponding to a variety of points in the Brillouin zone is made for the $R\overline{3}c({D}_{3d}^{6})$ structure. The Landau group-theoretical description of continuous transitions as formulated by Birman and Jari\ifmmode \acute{c}\else \'{c}\fi{} is the framework fo…
Abstract The TiKβ valence band spectra of a TiO 2 (rutile) single crystal are measured polarized parallel and perpendicular to the tetragonal c ‐axis. The shape of the spectra shows a strong anisotropy giving more information on the electronic structure of this substance than the corresponding unpolarized spectrum of…
Electrical resistivity measurements have been made on dilute and concentrated binary magnesium alloys containing Ag, Zn, Al, Nd, Pb, Sn and Th over the temperature range 77-320K. Small deviations occur from Matthiessen's rule for alloys that have been solution treated and quenched to retain the solid solution. Much la…
Mixtures of Cholesteryl Myristate (CM) and Cholesteryl Propionate (CP) were studied at four different concentrations. CM exhibits smectic, cholesteric and blue phases, while CP is a cholesteric liquid crystal. Addition of CP to CM disrupts the smectic phase while it enhances the cholesteric and blue phases. Ultrasonic…
The EPR spectra of Cr 3+ ion accompanied with a nearest neighbour oxygen vacancy (Cr 3+ -V o center) were observed over a temperature range from -150 to 200°C and showed `strong axial field lines'. The crystalline fields have been obtained as follows; | D |=84 GHz, | E |=2.6 GHz at 25°C, and | D |=120 GHz, | E |=23 GH…
Abstract Phase relations in the system PbO–PbSiO3 were determined at temperatures above 650 °C. Two new lead silicate phases, Pb5SiO7 and Pb11Si3O17 were found to be stable. The former melts incongruently at 733±1 °C to solid PbO plus liquid, and decomposes below 702±1 °C. The latter melts congruently at 728±1 °C. The…
The anisotropy field, coercivity and saturation magnetization in a Mn-Al-C permanent magnet were measured as a function of temperature from 4.2K to 300K. The coercivities in both the easy and hard directions were found to decrease linearly with temperature with slightly different slopes. The coercivities measured with…
Chrysophycean statospores identical to Chrysastrella furcata (Dolg.) Defl. of the ‘Chrysostomataceae’ have been found in Ontario lakes. Vegetative cells with 2–5 simple or forked spines of the type characterizing the statospore were discovered in West Twin Lake, Ontario in the early spring of 1979 and apparently repre…
Abstract The activated anionic polymerization of ε‐caprolactam in presence of LiCl (up to 10 wt.‐%) is studied under quasi‐adiabatic conditions. The temperature increase of the system, after proper corrections for the heat exchange with the surroundings, allows to evaluate the enthalpies of polymerization δ H p and to…