Materials Literature
按标题、摘要、年份、主题和来源检索公开元数据。结果保留作者、摘要、分类与原始来源链接。
Pyrazine-2,3-dicarbonitriles may be used as precursors for aza analogs of phthalocyanines (AzaPc's).Presently AzaPc's are receiving considerable attention, mainly due to their increased solubility compared to the parent phthalocyanines.Enhanced solubility is caused by the eight additional nitrogens in the macrocycle a…
In this paper, a small-angle neutron scattering study of gammaII-crystallins near their isoelectric point is presented. The experiments were carried out using protein concentrations of 5.7-85.7 mg/ml at temperatures in the range 11 -60 degrees C. The experimental data were analyzed using an ellipsoidal model for intra…
The 15-tert-butyl-5-oxophlorin 1 forms a stable, neutral π-radical species 2, in high yield; the 13,17-bis-unsubstituted 5-oxophlorin analogue 5, under similar conditions, affords the 15-iso-5-oxophlorin 6 and 15-hydroxy compound 7 (both characterized by X-ray crystallography), the latter demonstrating the trapping of…
TEMPO (2,2,6,6-tetramethylpiperidinyloxy) radical 1 and its derivatives 2–5 are found to form charge-transfer complexes with some acceptors such as TCNQF 4 (2,3,5,6-tetrafluoro-7,7,8,8-tetracyanoquinodimethane) or DDQ (2,3-dichloro-5,6-dicyano-1,4-benzoquinone) being isolated as solid substances.
X-ray diffraction (XRD), differential thermal analysis (DTA) and 27Al and 29Si solid state MAS-NMR techniques were used to monitor the fractionation steps of a brazilian smectite, previously crushed, from Campina Grande, Paraíba. The sand, silt and clay fractions were obtained by physical and chemical treatments. The…
PHYSICAL MODEL of shear strain rate produced by active micro-shear bands in metals is formulated and mathematical idealization of micro-shear bands system by means of the theory of singular surface of order one is proposed. Extension of the known averaging procedure over the representative volume element traversed by…
The coordination environment of Ti in eight Ti-bearing glasses of the Na Si ° -Na,Ti ° join (NTS) and in six ATY2 glasses (A20Ti02.2Y02, with A = Na, K, ~r Rb and y4 ;: Si or Ge) was determined using high-resolution, X-ray absorption near-edge structure (XANES) spectroscopy at the Ti K edge in ambient conditions. Five…
The purpose of this paper is to present the relationship between mechanical properties and thermoelectric properties of p-type Bi-Te polycrystalline materials. Semiconducting ceramics of p-type bismuth telluride were prepared by a hot press method. Their bending strength was over 40MPa and decreased with increasing pa…
The influence of grain size and grain boundary delta phase on the smooth and notch high cycle fatigue property at room temperature and 650% was investigated.This paper attempts to correlate the microstructure and fatigue property obtained during the initial development phase and certification of bar stock for compress…
Synthesis of β-SiAlON whiskers from pyrophyllite was investigated and the growth of the whiskers was explained by VLS (vapor-liquid-solid) mechanism. During heating, Fe2O3 in pyrophyllite was reduced by carbon derived from resin to Fe which further reacted with C to form an alloy (FexCy). When the temperature was abov…
Si 3 N 4 /MoSi 2 and Si 3 N 4 /WSi 2 composites were prepared by reaction‐bonding processes using as starting materials powder mixtures of Si‐Mo and Si‐W, respectively. A presintering step in an At‐base atmosphere was used before nitriding for the formation of MoSi 2 and WSi 2 ; the nitridation in a N 2 ‐base atmosphe…
Phase relations and lattice constants in the MgO–Al 2 O 3 –Ga 2 O 3 system at 1550°C have been determined experimentally. In a large part of this system, only a nonstoichiometric spinel is stable. Compositions as extreme as 12.5 mol% MgO–20.5 mol% Ga 2 O 3 –67 mol% Al 2 O 3 for a homogeneous spinel are possible. In th…
Reactions of (por)ZrCl2 [por = octaethylporphyrinato (oep) or tetraphenylporphyrinato (tpp) dianion] with TlCp and diphenylacetylene in the presence of Na/Hg or Mg produce novel low-valent zirconium porphyrin complexes (por)Zr(η5-Cp) 1 and (por)Zr(η2-PhCCPh) 2, respectively; spectroscopic and/or structural data for 1…
Optical and surface analysis techniques such as infrared spectroscopy, ellipsometry, and Auger electron spectroscopy (AES) and x‐ray photoelectron spectroscopy (XPS) have been used to study the way in which excess Si is incorporated in nonstoichiometric films deposited by a low pressure chemical vapor deposition techn…
Dispersion and localization of Pt species in mazzite zeolites (0.3% Pt) were studied using an in situ EXAFS technique in the fluorescence mode and transmission electron microscopy. It was shown that an ion exchange with a Pt(NH 3 ) 4 Cl 2 solution followed by calcination led to the formation of small clusters of PtO 2…
Spherical microporous reservoir-type microcapsules, fabricated using a W/O/W double emulsion technique with solvent evaporation and composed of 330 kD poly(beta-hydroxybutyrate-hydroxyvalerate (P(HB-HV)) (10.8% HV)/20% PCL II containing a range of bovine serum albumin (BSA) loadings, were incubated in Hank's buffer, p…
The oxidation behavior of Zr(Fe,Cr)2 precipitates being present at the surface of Zircaloy-4 was examined with microprobe Auger electron analysis, focussing attention on the oxidation behavior of chromium and iron in the early stage of oxidation where the oxide film was coherent. Chromium formed a thin oxide layer at…
The ability to discriminate between red, green and blue cotton fibres from various sources by comparing the microscopic characteristics and fluorescent properties (comparison microscopy) and visible spectra (microspectrophotometry) of the fibres in each colour group was assessed. A summary of the discriminating abilit…
The statics of isolated elastic domains (twins) in epitaxial thin tetragonal films grown on a cubic substrate is investigated theoretically. Different possible variants of the geometric shape of a domain are studied: plate, trapezoidal, and triangular. The nonuniform internal stresses, which also exist in polydomain e…
A vacuum ultraviolet photoionization study of atomic Ir in the region between 40 and 70 eV was performed with the use of monochromatized synchrotron radiation and photoion detection. The atomic beam of Ir was obtained with the technique of evaporating thin Ir wires. The photoion signals are compared with the theoretic…