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。
A bis(4-pyridyl)-porphyrin has been synthesised and shown to bind within the cavity of a host metalloporphyrin–pyromellitimide dimer; fluorescence quenching of the bound guest implies a photoinduced electron transfer to the pyromellitimide moieties of the host molecule.
X-ray diffraction patterns from layered structures yield detailed information on their structural parameters such as strain profile, chemical composition, layer thickness and interface quality. Any variation of the period, thickness of the individual layers, composition and homogeneity of the supelattics can be also d…
The barrier height for tautomerism of the inner protons of porphyrin is significantly influenced by specific reduction of the pyrrole rings. In the tetraphenyl derivatives of chlorin and bacteriochlorin an aromatic ring current was established 1 H NMR spectroscopically; in contrast, in the tetraphenyl derivative of is…
Intramolecular π–π interactions in two cofacial zinc porphyrin dimers have been probed as a model for porphyrin–porphyrin aggregation. Comparative studies of the binding of substituted pyridines using n.m.r., u.v./visible absorption and emission spectroscopy have allowed separation of the steric and electronic contrib…
It has long been a major preoccupation of materials users, whether implied or explicit, to tailor microstructures in order to adapt specific properties for a given application. In this context, the principal aim of the present review article is to consider the fundamental elements of polycrystal microstructures, i.e.…
Abstract Photoresponsive macromolecules are of interest both as novel organic materials for applications in photodevices and as models for photomodulated biological processes. The presence in polymer chains of photosensitive groups and of chiral groups capable of inducing optical activity into the polymer is very usef…
The time-resolved emission spectra of the tetranuclear clusters Cu4I4(py-X)4(X = H, 3-Cl, 4-Ph, 4-PhCH2, or 4-But) at 296 K in toluene each display separate, uncoupled emissions from two states, a short-lived (0.13–0.56 µs) metal-to-ligand charge transfer in the range 473–537 nm and a much more intense and longer live…
The microstructure evolution and grain growth during high-temperature heat treatment in ZrO2–4 and 8mol%Y2O3 alloys were examined. ZrO2–8mol%Y2O3 alloy was of single cubic phase (c-ZrO2), while ZrO2–4mol%Y2O3 alloy consisted of mixed grains of c-ZrO2 and tetragonal phase (t-ZrO2) with the equilibrium yttria contents a…
Thermal diffusivity and conductivity as well as specific heat of capsule-HIPped Si3N4 with Y2O3 and Al2O3 6mol% in total as additives were measured at different temperatures ranging from 100 to 1300K. The isobaric specific heat Cp agreed with the isochoric specific heat Cv calculated by the Debye's theory, assuming th…
Switching between two different smectic layer structures, chevron and bookshelf geometries, was observed for the first time in ferroelectric liquid crystal cells. In the absence of an electric field, a chevron layer structure is formed, as in a usual smectic C * phase. An electric field induces layer switching to a bo…
Abstract The kinetic parameters of the thermal decomposition of poly(aryl‐ether‐ether‐ketone) (PEEK) in a nitrogen atmosphere have been obtained using an isothermal weight‐loss method. Several mathematical approaches have been used to obtain the Arrhenius parameters based upon the use of different reaction models. The…
The synthesis and characterization of the ligand 1,8-bis(3,5-dimethyl-1-pyrazolyl)-3,6-dithiaoctane (bddo) and its co-ordination compounds with zinc, cobalt, nickel, and cadmium thiocyanate are described. The general formula is M(bddo)(NCS)2 with M = Ni, Co, or Zn. With cadmium, Cd2(bddo)(NCS)4 was found. X-Ray struct…
The adsorption and subsequent detergent elutability of fibrinogen and albumin were measured on various treated and untreated polymer films in order to determine whether the relative adsorption of these proteins was responsible for the enhanced thromboresistance of Dacron vascular grafts treated with tetrafluoroethylen…
Joint i.r. and microcalorimetric work has shown that two types of CO adsorb on pure anatase: one (species A) absorbing at 2184–2188 cm–1, has an adsorption heat of ca. 52 kJ mol–1, the other (species B), absorbing at 2203–2208 cm–1, has an adsorption heat of 69 kJ mol–1. When sulphates are present at the surface, left…
The relative sensitivity of an analytical electron microscope and energy-dispersive x-ray detector to x-rays of various elements is investigated through an extensive kASi factor study. Elemental standards, primarily National Bureau of Standards multielement research glasses, were dry-ground into submicrometer-sized pa…
Barium ferrite fine particles have been synthesized from ferric nitrate and barium nitrate aqueous solution by an aerosol technique. The as-received particles showed a spin-glass behavior with a history-dependent low-field magnetization below 180 K. An exothermic peak with an initial crystallization temperature of 687…
Treatment of VOCl42– with tca–(tca–= thiophene-2-carboxylate) under aerobic conditions leads to formation of [V5O9Cl(tca)4]2–, whereas if AgNO3 is also present, the product is [V4O8(NO3)(tca)4]2–; the two anions have been isolated as NR4+ salts and their unusual structures elucidated by crystallographic methods.
The effect of heat treatments on martensitic transformations in monocrystalline Cu–14.1Al–4.2Ni (mass%) (alloy 1) and Cu–14.7Al–4.2Ni (mass%) (alloy 2) shape memory alloys has been investigated by means of differential scanning calorimetry measurements, optical microscopy and tensile tests of martensitic specimens. As…
Substituted cycloalkanones, 1-phenylalkanones, and open-chain ketones are oxidatively cleaved by the title compound under very mild conditions.
Seeding a mixture of boehmite (AIOOH) and colloidal ZrO 2 with α‐alumina particles and sintering at 1400°C for 100 min results in 98% density. The low sintering temperature, relative to conventional powder processing, is a result of the small alumina particle size (∼0.3 μm) obtained during the θ‐to α‐alumina transform…