Volume interactions in the statistical physics of a polymer macromolecule
ОБЪЕМНЫЕ ВЗАИМОДЕЙСТВИЯ В СТАТИСТИЧЕСКОЙ ФИЗИКЕ ПОЛИМЕРНОЙ МАКРОМОЛЕКУЛЫИ, М, Дифгииц, А
Materials Literature
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Up-conversion studied by selective time resolved excitation techniques in Pr3+ : LaF3
A strong blue fluorescence has been observed following orange-yellow laser excitation in the 1D2 multiplet of Pr3+ : LaF3. This blue fluorescence has different time evolution depending on the excitation wavelength within the absorption line. Time resolved excitation techniques have been used to study this time evoluti…
Elastic properties of single-crystal NaCl under high pressures to 80 kbar.
Adiabatic elastic moduli for a NaCl single-crystal under high pressures up to 80kbar at room temperature were determined through ultrasonic sound velocity measurements in a cubic anvil-type high pressure apparatus with a solid pressure transmitter. Ultrasonic measurements far both the longitudinal and transverse waves…
Procollagen segment-long-spacing crystallites: their role in collagen fibrillogenesis.
Naturally occurring segment-long-spacing crystallites of procollagen collagen have been found in the culture medium of fibroblasts from chick embryo tendon, human skin, and dermatosparaxic calf skin; in whole-mount preparations of cultured human skin fibroblasts; in homogenates of lathyritic chick embryo tendon, carti…
Landau theory of the reentrant nematic-smectic A phase transition
The reentrant, nematic to smectic A phase transition is shown to follow from the Landau theory if one assumes the existence of an optimum density for smectic ordering. The shape of the coexistence line in the P-T plane is fit exactly by this theory. The effects of concentration on reentrant behaviour are also explaine…
Physical Properties of One Dimensional Conductors
In the course of investigations of organic metals we have investigated the cation-radical series TMTTF2-X′ with X′ = BF4, ClO4, PF6, SCN and Br. On this isomorphous series a large range of physical properties have been studied: electrical conductivity, magnetic susceptibility, EPR, optical reflectivity and specific he…
Dependence of albumin–fibrinogen simple and competitive adsorption on surface properties of biomaterials
Abstract Adsorption of fibrinogen and albumin from solutions of the proteins singly and in mixtures was studied. A variety of surfaces with varying degrees of hydrophilicity and thrombogenicity was investigated. Adsorption behavior shows a strong dependence on surface properties. All surfaces show a preference for fib…
Surface structure and surface states in magnesium oxide powders
The photoluminescent and reflectance spectra of MgO smoke have been compared with the spectra of MgO ex-hydroxide and ex-carbonate. Parallel studies by electron microscopy have shown that a strong correlation exists between the optical spectra and the different morphology of the particles obtained by the different rou…
Purification of the mannitol-specific enzyme II of the Escherichia coli phosphoenolpyruvate:sugar phosphotransferase system.
The inducible, mannitol-specific Enzyme II of the phosphoenolpyruvate:sugar phosphotransferase system has been purified approximately 230-fold from Escherichia coli membranes. The enzyme, initially solubilized with deoxycholate, was first subjected to hydrophobic chromatography on hexyl agarose and then purified by se…
Thermal expansion of .GAMMA.-Mg2SiO4.
Thermal expansion of γ-Mg2SiO4 was measured with X-ray powder diffraction method up to 750°C at atmospheric pressure. The data are analyzed in terms of Gruneisen's theory of thermal expansion and Gruneisen's parameter is obtained to be 1.27. Volume thermal expansion coefficient is 19 at 20°C and 27 at 500°C in unit of…
Étude ultrasonore des phénomènes critiques dans les gels
Nous avons mesuré les variations d'atténuation et de vitesse ultrasonores dans un gel acrylique. En comparant ces résultats avec ceux obtenus dans le solvant pur (H2O), nous avons pu en déduire la constante élastique propre du gel et le coefficient de friction entre le réseau et le solvant. Une étude en fonction de la…
A tentative description of the crystallography of amorphous solids
A number of continuous random lattices can be classified as specific one-to-one mappings of ordered lattices of spaces of constant curvature onto the usual 3-dimensional euclidean space. These mappings put emphasis on two types of lattice defects : surface defects for spaces of constant positive curvature (i.e. spheri…
Degradation of Adhesion of Coated Tire Cords to Rubber by Atmospheric Pollutants
Atmospheric conditions, whether at room temperature or in high temperature ovens, do not consist of pure environments. Resorcinol-formaldehyde-latex (RFL) dipped nylon and polyester tire cords lose adhesion to rubber stocks upon exposure to environmental pollutants. Adhesion degradation is most severe upon exposure to…
Erosion Damage in Carbon-Carbon Composites at Hypersonic Impact Velocities
The damage to three-dimensional orthogonal carbon-carbon composites created by particle impacts ranging from 1800 to 6000 ms-1 has been characterized for three weave constructions at both ambient and temperatures up to 3600¼C. The subsurface damage modes in the vicinity of the impact crater are described for the range…
Temperature Dependence of Elastic Moduli of Several Steels at Low Temperature Range
The ultrasonic wave reflection method has been used to determine the elastic constants of various steels at the temperature range from room temperature to -196°C. Liquid nitrogen was used as a cooling agent. The data of the temperature dependence of elastic moduli for commercial alloys and steels were given in tables…
Effect of Temperature and Deformation Rate on Fracture Strength of Sintered Uranium Dioxide
The fracture strength of two kinds of UO2 specimens possessing pores of different maximum sizes (60 and 140 μm) was measured in the range of room temperature − 1,300°C by means of diametral compression testing. The fracture strength thus obtained proved to be smaller than any of the values reported by previous authors…
A simple turbidimetric method for determination of exchangeable soil potassium
It was found that sodium tetraphenylboron, NaB(C6H5)4, can be used as a reagent for determination of K in acid sodium acetate extracts of soils. After extraction and filtration, sodium hydroxide and formaldehyde are added prior to the reagent to avoid interference of ammonium. At low concentrations of K in the extract…
Absorption of hydrogen by titanium–cobalt and titanium–nickel intermetallic alloys. Part 2.—Thermodynamic parameters and theoretical models
Thermodynamic relationships are derived which allow experimental enthalpy, entropy and free energy data for metal–hydrogen systems to be converted to conditions of constant volume. Discrepancies between these relationships and the equations developed by other workers are discussed. The relationships are used to conver…
Solid solution in the CaO—MnO system
CaO–MnO samples have been prepared by thermal decomposition of mixed carbonates and annealing of the resulting oxide mixtures at 1273 and 1523 K in vacuo. Cooled samples have been ground in vacuo and transferred for X-ray powder diffraction analysis and e.p.r. analysis without exposure to the atmosphere. Lattice param…
Hydrogen in Metals
A brief summary is presented of the known effects of hydrogen on metals, especially degradation and embrittlement. Practical problems involving hydrogen are surveyed. Résumé On présente un bref résumé des effets connus de l'hydrogène sur les métaux, surtout en ce qui a trait à la dégradation et la fragilisation de ceu…