Materials Literature
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A nemato-hydrodynamic theory of shear thinning in solutions of lyotropic nematic-liquid-crystal polymers (LCP's) consisting of semiflexible polymer molecules is developed. It is based on an effective two-media theory assuming a percolative flow of solvent through globularly shaped polymer arrays, which are supposed to…
Abstract Adsorption of a strongly bound absorbate in a bidisperse‐pore system is modeled using a Turner pore structure. This idealized system leads to an analytical solution for the micropore uptake of adsorption that is valid for a part of the adsorption‐time profile. The analytical solution yields a well‐defined cri…
The vibrational spectra of crystalline MSO4 where M=Ba, Sr, and Pb are reinterpreted in terms of a vibrational unit cell (Imma) which is one-half the size of the crystallographic (Pnma) unit cell.
The oxygen potentials and lattice parameter of oxide fuels (UO2 and UO2-2 w/0Gd2O3) irradiated in commercial BWRs have been measured by using a solid electrolyte galvanic cell technique and X-ray diffractometry. The fuel burn-up was 13–30 GWd/t for the former measurements and 6–35 GWd/t for the latter. The oxygen pote…
Postulated long-term loss of coolant accidents (LOCA) for the International Thermonuclear Experimental Reactor (ITER) may involve the ingress of air or steam into the plasma chamber. Reactions of these gases with the hot plasma facing components will cause oxidation, transport, and release of activated species. To pre…
Abstract A study of the mechanism of thermal oxidative and thermal mechanical degradation of isotactic polypropylene (PP) is reported. Size exclusion liquid chromatography has been applied to the study of molar mass distribution (MMD) of samples of PP under oxidative degradation in the presence of an incorporated orga…
Endothelial cells (EC) covering the blood-contacting surface of a prosthetic material could potentially enhance the subsequent nonthrombogenicity of the surface. In order to create such a surface, the EC must become attached to the surface, spread and ultimately form a monolayer. In this study we examined several fact…
Thromboembolic complications are a major obstacle for the permanent use of artificial cardiac prostheses. Many of these complications are caused by the intrinsic thrombogenicity of the biomaterials, which are used to cast the luminal blood sac. Numerous attempts have been made to improve the hemocompatibility of the n…
Abstract We will review experimental results obtained recently on the determination of the laws governing the growth process of polymer clusters as the gel point is approached. The exponent γ which characterizes the increase of the mean weight‐average molecular weight M w as the gel point is approached and the exponen…
Substitutional diffusion coefficients D of Hf, Ta and Pb have been measured α- Zr single crystals and the diffusion profiles analysed by Rutherford backscattering (Hf, Ta and Pb) and secondary-ion mass spectrometry (Hf). Measurements were made either parallel (D ‖) or perpendicular (D‖ ) to the specimen c axis. Althou…
Reaction‐bonded Si 3 N 4 · TiN and Si 3 N 4 · Al 2 O 3 composites were successfully fabricated by heating mixed powder compacts of Si and TiN or Si and Al 2 O 3 in a nitrogen atmosphere. The former showed electrical conductivity, owing to the presence of TiN. An electrical resistivity of 2.6 × 10 −5 Ω· m was obtained…
Abstract Durch Symproportionierung von elementarem Selen und Selentetrabromid in polaren protischen Lösungsmitteln wurde eine neue Klasse tri‐, tetra‐ und pentanuklearer Bromoselenate(II) dargestellt. In 2‐Methylpropionitril als Lösungsmittel wurde das strukturell neuartige Ion [Se 3 Br 8 ] 2− stabilisiert und als sch…
The BEATRIX-II experiment in FFTF is an in-situ tritium recovery experiment to evaluate the tritium release characteristics of Li2O and its stability under fast neutron irradiation to extended burnups. This experiment includes two specimens: a thin annular ring specimen capable of temperature transients and a solid te…
Silicon aluminium oxynitride (β′ sialon) powders have been prepared by reacting kaolin–carbon mixtures at 1400–1500°C in flowing nitrogen. The kaolin/carbon ratio in the starting mixtures must be accurately controlled to obtain single phase β′ powders. The overall reaction rate increased with increasing nitrogen flowr…
Abstract Mit Hilfe von Mott‐Schottky‐Analysen und photoelektrochemischen Untersuchungen wurden die Halbleitereigenschaften von Passivfilmen auf AISI 304 charakterisiert und mit dem Auftreten von Stromtransienten, welche aus metastabilen Lochkorrosionsvorgängen resultieren, verglichen. Es zeigte sich, daß das Potential…
Abstract When the coupling agent is dissolved homogeneously in water, the hydrolysis rate of the alkoxy group is influenced by the pH of the solution, the size of the alkoxy group, and to a lesser extent, the size of the organofunctional group directly attached to the silane atom. We have quantitatively studied the re…
A mechanism is proposed for the radiolysis which occurs in soda‐silicate glasses when they are irradiated. The mechanism is consistent with the observations of the reaction products which are produced and the rates at which the decomposition proceeds.
Abstract Aluminous lateritic soils from Governor's Harbour, Eleuthera, Bahamas are described. These soils are forming on eolian ridges under a humid, tropical savanna climate. The parent material is carbonate eolianite plus airborne dust from North Africa. The soils are thin, discontinuous and concentrated in shallow…
We present in this paper a comprehensive study of the static and dynamic properties of point defects and of their interaction with dislocations and grain boundaries. First, by using short-range pair potentials fitted to physical parameters of Mg and Zr, we calculate defect configurations and associated energies. Two d…
The fractions of absorbed, backscattered, and transmitted electrons bombarding a thin solid film are calculated as functions of the film thickness both in the absence and in the presence of a substrate. The depth distribution of the absorbed electrons has also been calculated.