Materials Literature
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Abstract The minerals of biology have two components, one of which is inorganic and the other organic. Understanding rests initially in the description of the factors that control the nucleation and growth of the inorganic components in the absence of organic materials, and in the study of the organic materials in the…
Collagen is the principal organic matrix in bone. The triple helical region of the molecule is 1014 amino acids long. In fibrils these molecules are staggered axially by integers of 234 residues or 68 nm (D). This axial shift occurs by self-assembly and can be understood in terms of a periodicity in the occurrence of…
Abstract Coccoliths are delicate calcified structures produced by marine unicellular algae. In the species Emiliania huxleyi the calcium carbonate (mostly calcite) is closely associated with a complex, acidic polysaccharide which binds calcium ions specifically, interferes with the in vitro crystallization of calcium…
Small polystyrene particles coated with a high Mr non-ionic surfactant (Poloxamer 338) are diverted from the reticuloendothelial system of the liver and spleen to other tissue sites. These results are discussed in terms of the adsorption of the Poloxamer to the particle surface and the implications for drug targeting.
Abstract Mollusc shells are used as a model for studying ‘organic-matrix -mediated’ biomineralization, in which crystals are nucleated and grow in a pre-formed structural framework composed of proteins and polysaccharides. In particular, the possibility that the organic matrix functions as a template for crystal forma…
Abstract High-resolution electron microscopy, in conjunction with controlled specimen preparation procedures, has enabled the nature and structure of novel {100} platelet defects found in TiO2-x (0 < x < 0.0035) to be studied at close to atomic resolution The precipitation of these platelet defects, ofte…
The incommensurate phase of krypton on graphite is studied by use of the molecular-dynamics simulation technique for systems with graphite substrate dimensions comparable to present-day laboratory capabilities. At low temperature and for all coverages, honeycomb networks of "heavy" domain walls are observed for the fi…
Abstract A new chlorination mechanism has been suggested for polyethylene crystals. Based on electron microsocopy and infrared spectroscopy of chlorinated high‐density polyethylene single crystals, it is proposed that beyond the initial chlorination of the lamellae surfaces, which accounts for only 2‐3% chlorine uptak…
Abstract The 13 C NMR spectra of tetraalkyl‐porphyrin and ‐chlorin complexes of nickel(II) were studied. The 13 C NMR of (5,10,15,20‐tetramethylchlorinato)nickel(II) supports the model of asymmetric charge distribution in this chlorin, as derived from the structure analysis and from previous proton NMR studies.
Abstract An unsteady‐state method for determination of the thermal diffusivity of a porous sphere, based on direct contact condensation of steam, was developed. A modified formula relating thermal diffusivity to porosity was proposed from theoretical considerations. Experimental measurements on known solids showed goo…
An experimental and numerical verification of profiles predicted by Cheo et al. [ J. Opt. Soc. Am.67, 1686 ( 1977)] for simultaneous TE- and TM-blazed triangular groove gratings is given. Corrected values also presented. The experimental results at 35 GHz show an n = −1 order diffraction efficiency as high as 99.9% fo…
An improved approach to the mechanical modeling of fuel rod performance is presented. Previous computer modeling has centered around a unified finite element approach with both fuel pellets and cladding being represented by ring elements. The fuel mechanical analysis code (FUMAC) departs from these approaches in two a…
Soil samples were collected from former radium processing sites in Denver, CO, and East Orange, NJ. Particle-size separations and radiochemical analyses of selected samples showed that while the greatest contents of both 226Ra and U were generally found in the finest (less than 45 micron) fraction, the pattern was not…
The Weeks–Chandler–Anderson perturbation theory is derived for one-dimensional Lennard–Jones systems. Its predictions are tested with molecular dynamics calculations on the full and repulsive Lennard–Jones potential. It is found that the prescription for the reference fluid is in excellent agreement with the computer…
The reflectance of liquids squalane and squalene between 2 and 25 eV have been determined by closed cell double ionization chamber methods. Kramers–Kronig analysis of the data gives optical functions from which are calculated the dielectric functions, energy loss functions, and mean free path for photons and electrons…
Abstract Diffraction intensity data of well ordered protoenstatite, MgSiO 3 , inverted from orthoenstatite, were collected at 1260°C and 1360°C by means of four-circle diffractometry using a gas flame heater. The effect of temperature on the structure of protoenstatite was studied based on these data and those at 1080…
Films of Cu 2 O , 30 μm thick, have been grown on copper metal foil at 1000°C in 1 % O 2 / Ar , heat‐treated without O 2 present at a number of lower temperatures, and quenched in water. The room temperature emission at 980 nm and its excitation spectrum, attributed to relaxed excitons at copper vacancies, are similar…
The character and extent of fuel/cladding chemical interaction (FCCI) have been established for mixed uranium-plutonium oxide, (U,Pu)O2, fuels irradiated in Experimental Breeder Reactor-II to peak fuel burnups to 14.5 at.% at beginning-of-life peak cladding temperatures to 730°C. The changes in character and the corre…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTCarbon-13 and deuterium NMR spectroscopy of high-spin manganese(III) porphyrin halide and pyridine complexesHarold M. Goff and Andrew P. HansenCite this: Inorg. Chem. 1984, 23, 3, 321–326Publication Date (Print):February 1, 1984Publication History Published online1 May 2002P…
Abstract Aus KSn bzw. RbSn entstehen durch direkte Oxydation K 2 Sn 2 O 3 bzw. Rb 2 Sn 2 O 3 bei 320°C bzw. 410°C die bislang unbekannten „Tieftemperaturformen”︁ (a = 8,4100(8)Å bzw. a = 8,6368(8)Å), isotyp mit kubischem K 2 Pb 2 O 3 . Bei höherer Temperatur (510 bzw. 520°C) entstehen die bekannten Hochtemperaturforme…