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。
Abstract Surface‐enhanced Raman spectra of some amino acids (Phe, Tyr, Trp, His, Leu and Ala) and cytotoxin I from Naja naja oxiana adsorbed by silver hydrosols have been obtained. The spectra are enhanced from 100 to 200 times. Addition of aqueous solutions of the amino acids to the hydrosol resulted in the appearanc…
Three topical fluoride agents deposited surface coatings of different morphology and thickness on intact human enamel surfaces. The agents studied were an acidic silane fluoride lacquer, a neutral NaF lacquer, and an APF gel. Each agent reacted with the enamel surface differently, producing its own distinctive etching…
The reflectivity spectra have been measured on single crystals of CaO, CaS, SrO, SrS, SrSe, BaO, BaS and BaSe in the syncrotron radiation region of 440 eV. In order to prevent surface deterioration effect, all measurements have been made at 77 K on the fresh (100) surfaces cleaved within a high vacuum. From a chemical…
For ceramic AgNb03 the occurrence of a ferroelectric phase was ascertained at temperatures less than about 75°C. In the vicinity of this temperature, the functions of dielectric permittivity ∊, loss tangent tan δ, spontaneous polarisation Ps, total pyroelectric coefficient pt and the piezoelectric coefficient d33 vers…
The cholesteric blue phases (BP I and BP II) can be modeled as cubic lattices of disclinations in a cholesteric matrix. In an earlier paper we presented results of free-energy calculations for three models with ${O}^{2}(P{4}_{2}32),{O}^{5}(I432)$, and ${O}^{8}(I{4}_{1}32)$ space-group symmetry. In the present paper ca…
A newly developed electro-acoustic transducer technique is applied to the measurement of electric field intensity at a dielectric/electrode interface. This report describes the principles of this new technique as applied to: the residual electric field intensity by a sheet charge and its location in PET film, to the a…
Abstract Heptamethyl cobyrinate perchlorate, [Cob(II)ester]ClO4, was prepared in a good yield from cyanocobalamin. This hydrophobic complex is structurally comparable to the base-off form of vitamin B12r. Thermodynamic parameters (ΔG, ΔH, and ΔS) for axial ligation of [Cob(II)ester]ClO4 with various amines in dichloro…
A solution is given of the field equations of nonlocal elasticity for a line crack interacting with a screw dislocation in an elastic plane under antiplane shear loading. Displacement and stress fields are determined throughout the core region and beyond. In the case when the dislocation is absent, the circumferential…
Helium bubble nucleation has been studied at grain boundaries in a ternary austenitic steel after helium implantation in the temperature range 450–600°C. Transmission electron microscopy shows that all interfaces except the coherent twin are preferred nucleation sites for bubbles, and that the density of bubbles is gr…
Measurements are reported of the temperature dependence of the proton spin-lattice and spin-spin relaxation times ${T}_{1}$ and ${T}_{2}$ in yttrium and lanthanum dihydrides containing controlled levels of gadolinium as low as 50 ppm. The results demonstrate unambiguously that paramagnetic ions in concentrations so lo…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTAnthracene pillared cofacial diporphyrinC. K. Chang and Ismail AbdalmuhdiCite this: J. Org. Chem. 1983, 48, 26, 5388–5390Publication Date (Print):December 1, 1983Publication History Published online1 May 2002Published inissue 1 December 1983https://pubs.acs.org/doi/10.1021/j…
A biotite that has substantially altered to chlorite in a granitic rock from south-central Maine has been investigated with high-resolution and analytical transmission electron microscopy. The reaction takes place primarily by the replacement of TOT mica layers in the biotite by brucite-like layers (mechanism 2). This…
Magnesian calcites with compositions between 0 and 24 mole% MgCO 3 were synthesized at high temperatures and pressures in cold-seal pressure vessels and in a piston-cylinder apparatus. X-ray powder diffraction and atomic absorption analyses of these phases reveal a non-linear, but smooth, variation in volume and c/a w…
A single-crystal X-ray study indicates that the perovskite form of CaGeO 3 is orthorhombic (Pbnm), and isotypic with GdFeO 3 , although it was previously reported as a cubic form. The crystal structure is close to that of Sm-AlO 3 . Although the unit cell of CaGeO 3 is pseudocubic, the structure itself is very distort…
The interatomic coupling of magnetic moments in the insulating antiferromagnetic transition-metal compounds MnO, MnS, and NiO is calculated using a theory based on the itinerant-electron picture (energy-band theory and the local-spin-density treatment of exchange and correlation). Calculated values of these "Heisenber…
Abstract Epitaxial crystallization of polyethylene, n ‐paraffins, aliphatic polyesters, and various polyamides has been achieved on benzoic acid crystal substrates, specifically on their (001) crystals faces, which are made up of the aromatic rings. The epitaxial relationship is very similar for all polymers investiga…
Raman spectra are reported for crystalline anorthite (An), calcium Tschermak's pyroxene (CaTs), gehlenite (Geh), and glasses of CaAl 2 Si 2 O 8 (An), CaAlAlSiO 6 (CaTs), and Ca 2 AlAlSiO 7 (Geh) composition. A small degree of Si-Al disorder in anorthite is indicated by the presence of weak Si-O-Si antisymmetric stretc…
Abstract The unique properties of imogolite are closely related to its structure, which is a tube of 23–27 Å outer diameter and ∼10 Å inner diameter, with an AIOH outer surface and SiOH inner surface. Acid dispersions contain the long, positively-charged tubes as isolated units or small bundles, which form bulky gels…
Mullite ceramic, transparent in the infrared, was prepared by hot‐pressing and hot‐isostatically pressing starting materials derived from alkyloxides. A composition with 72.3 wt% Al 2 O 3 yielded transparent, submicrometer grain size bodies at 1630°C, whereas higher temperatures produced glass‐containing microstructur…
Diatom immigration rates were affected by changes in current patterns similar to those found around substrates in streams and were increased by changes in microhabitat characteristics similar to those autogenically generated during diatom community development. Diatom abundances on tiles exposed for 24 h, i.e., diatom…