Materials Literature
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The (100) and (101) interplanar spacings of 400 mesh quartz powder were measured by high-temperature X-ray diffractometry from 22 to 1400°C. Expansion through the high-low transformation was reversible and continuous, with evidence of 1–2° hysteresis; expansion from 574 to 1000° is zero, with a net decrease from 1000…
Abstract Photoelectron spectra were measured in the region between 6 and 21 eV for aniline, N,N-dimethylaniline, phenol, anisole, benzonitrile, acetophenone, nitrobenzene, and their methyl derivatives. The observed spectra were interpreted in terms of their MO’s obtained by the CNDO/2 and EHMO methods, the methyl-subs…
The three dimensional structure of the lysozyme from bacteriophage T4 has been determined from a 2.5 A resolution electron density map. About 60% of the molecule is in a helical conformation and there is one region consisting of antiparallel beta-structure. The polypeptide backbone folds into two distinct lobes linked…
Abstract This is a study of materials which are positive‐temperature‐coefficient resistors. Such materials, composed of conductive particles dispersed in a crystalline polymeric matrix, have been found to be of limited stability. An example is carbon black in high‐density polyethylene. On repeated cycling through the…
Fracture strengths (δ), fracture‐initiating flaw sizes, and mirror radii ( r ), as outlined by either the mist or the hackle boundary, were measured for silicate and nonsilicate glasses (e.g. As 2 S 3 and glassy carbon). For all glasses, δr 1/2 = constant. The average ratios of inner and outer mirror radii to flaw siz…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTGrowth of calcium phosphate on hydroxyapatite crystals. Effect of supersaturation and ionic mediumG. H. Nancollas and B. TomazicCite this: J. Phys. Chem. 1974, 78, 22, 2218–2225Publication Date (Print):October 1, 1974Publication History Published online1 May 2002Published in…
CONTENTS INTRODUCTION 167 NONMEMBRANE-ENCLOSED INCLUSIONS 168 Polyglucoside (a, Glycogen) Granules 168 Polyphosphate (Volutin, Metachromatie) Granules 168 Cyanophycin (Structured) Granules 170 Ph ycobilisomes 171 Crystals and Paracrystalline Arrays 172 Tubules, Microtubules, and Raphidosomes 176 MEMBRANE-ENCLOSED INCL…
Machine learning (ML) is transforming all areas of science. The complex and time-consuming calculations in molecular simulations are particularly suitable for an ML revolution and have already been profoundly affected by the application of existing ML ...Read More
Single crystals of pure copper oriented for single slip were fatigued in air at room temperature at low constant plastic strain amplitudes in the range 0·1 % ≤ e p≤ 0·6%. After a few thousand cycles the specimens entered what appeared to be an equilibrium state which contained two phases: a hard and almost inactive ‘m…
Absorption and reflection spectra of β-Ga 2 O 3 are measured with polarized light in the wavelength region near its absorption edge. The crystals of β-Ga 2 O 3 are grown by using a Ga/HCl/O 2 /Ar vapor reaction system. The platelike crystals of β-Ga 2 O 3 have (100), (010), and (001) surfaces, and the major surface is…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTTechnique for the determination of absolute emission quantum yields of powdered samplesMark S. Wrighton, David S. Ginley, and David L. MorseCite this: J. Phys. Chem. 1974, 78, 22, 2229–2233Publication Date (Print):October 1, 1974Publication History Published online1 May 2002…
Using a formalism developed by Stroh (1962), a simple image force theorem for a dislocated anisotropic bicrystal is derived. An extension of the Stroh formalism, shows that the prelogarithmic energy factors depend only on the crystallographic directions of the dislocation line and its Burgers vector relative to each m…
The elastic properties of copper have been compiled and reviewed. Polycrystalline elastic constants included are: Young's modulus, the shear modulus, the bulk modulus, and Poisson's ratio. Single-crystal constants of second-, third-, and fourth-order are included. Over 200 references to the experimental literature are…
Optical and x-ray observations of polyethylene have been made at high pressures and temperatures using a gasketed diamond-anvil cell. The experiments confirm the existence of the high-pressure phase previously postulated by Bassett and Turner. The new phase is hexagonal, with orthohexagonal lattice parameters of a = 8…
Abstract Native cellulose has been shown to consist of a crystalline array of parallel chains, based on the X‐ray diffraction data for specimens from the sea alga Valonia ventricosa . The unit cell is monoclinic with dimensions a = 16.34 Å, b = 15.72 Å, c = 10.38 Å (fiber axis), and β = 97.0°. The space group is P2 1…
This review discusses the physical properties of nematic, cholesteric, and smectic liquid crystals. Molecular theories of the liquid crystal phases are discussed and the molecular field theories of the phase transitions between the various liquid crystal phases are presented. The elastic theory and hydrodynamics of li…
We show core-electron energy spectra determined by means of (soft) x-ray photoelectron spectroscopy and appearance potential spectroscopy to be closely related for $2p$ electrons in iron and nickel. An earlier comparison for the first transition-series elements had indicated a systematic difference between appearance-…
In a new technique for studying electron collisions, the electrons are confined by electromagnetic fields and exposed to a known low density of atoms or molecules. Collisions rates are measured by electron diffusion in the trap. The use of spin-oriented atoms allows triplet and singlet contributions to be separated. R…
The dislocation velocity, , on prismatic planes of monocrystalline MgZn2 has been determined by etching as a function of applied stress, τ, chemical composition within the homogeneity range, and temperature, T, between 340 und 456°C. The results are interpreted in terms of a double kink mechanism, where
Doping processes of silicon carbide crystals with scandium are investigated. It is shown that the scandium solubility in SiC is limited within the 1800 to 2600°C temperature range and amounts to (2 to 3) × 1017 cm−3. On doping silicon carbide crystals with scandium the VLS growth mechanism is possible. The luminescenc…