Materials Literature
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Sensitivity analysis is considered for kinetics problems defined in the space–time domain. This extends an earlier temporal Green’s function method to handle calculations of elementary functional sensitivities dui/daj where ui is the ith species concentration and aj is the jth system parameter. The system parameters i…
We show that the spontaneous decay of a phonon by anharmonic processes of any order into a set of phonons of higher phase velocity is impossible for both $N$ and $U$ processes. The result is valid for crystals of arbitrary symmetry and anisotropy and in the presence of frequency and angular dispersion. The implication…
Extended-x-ray-absorption-fine-structure (EXAFS) data on the normal and superionic phases of AgI and the cuprous halides have been analyzed using four structural models: harmonic oscillator, displaced site, anharmonic oscillator, and excluded volume. The most satisfactory description is obtained with the last model, b…
Structural defects in glassy ${\mathrm{As}}_{2}$${\mathrm{Se}}_{3}$ are classified and labeled according to the constituent like-atom bonds and malcoordinated atoms. A selection rule is formulated to reduce the number of allowed Fermi-level pinning reactions. An elementary Bethe-lattice model is introduced as a starti…
The drift velocity of holes in natural diamond is analyzed for a wide range of temperatures $85\ensuremath{\le}T\ensuremath{\le}700$ K and fields ${10}^{2}<E<6\ifmmode\times\else\texttimes\fi{}{10}^{4}$ V/cm applied parallel to $〈100〉$ and $〈110〉$ crystallographic directions. Experiments are carried out with the…
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…