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。
The diffraction of X-rays by a thin layer (of the order of a few nanometres) with a gradient in interplanar spacings is considered. It is shown that optical coherence over the film thickness leads to diffraction peak positions that no longer obey Bragg's law. Although a fitting of the diffracted intensity is indeed st…
Abstract The thermal and mechanical properties of polyurethane‐infiltrated carbon foam of various densities were investigated. By combining the high thermal conductivity of the carbon foam with the mechanical toughness of the pure polyurethane, a mechanically tough composite (relative to the unfilled foam) that could…
Abstract Silk fibroin ( Bombyx mori ) was sulfated with an aqueous sulfuric acid solution. The sulfated fibroin was characterized by Fourier transform infrared spectroscopy (FTIR), amino acid analysis, and gel filtration chromatography (GFC). Maximum yield was obtained at around 2–4 h, and it decreased at 6 h and more…
We study the growth and internal structure of polyelectrolyte multilayers obtained by combining three polyanions with nine polycations of the ionene family, of systematically varied chemical architecture. We find that, contrary to a generally held belief, ordered organic multilayers are by no way exceptional, provided…
Nucleation and growth of thin films of Ag on the fivefold surface of an ${\mathrm{Al}}_{72}{\mathrm{Pd}}_{19.5}{\mathrm{Mn}}_{8.5}$ icosahedral quasicrystal is studied with scanning-tunneling microscopy. For low coverages, flux-independent island nucleation is observed involving adatom capture at ``traps.'' With incre…
Branching can have a dramatic effect on the properties of polymers, and bisphenol A polycarbonate (BPA−PC) is no exception. We describe here the results of a density functional (DF) study of branching that can occur during transesterification reactions in BPA−PC in the presence of catalysts. We find that sodium phenox…
Because of the relatively low-resolution diffraction of typical protein crystals, structure refinement is usually carried out employing stereochemical restraints to increase the effective number of observations. Well defined values for bond lengths and angles are available from small-molecule crystal structures. Such…
The room temperature iron K-edge X-ray absorption near edge structure spectra of (Fe[HC(3,5-(CH(3))(2)pz)(3)](2))I(2) and (Fe[HC(3,5-(CH(3))(2)pz)(3)](2))(BF(4))(2) have been measured between ambient and 88 and 94 kbar, respectively, in an opposed diamond anvil cell. The iron(II) in (Fe[HC(3,5-(CH(3))(2)pz)(3)](2))I(2…
Abstract For Abstract see ChemInform Abstract in Full Text.
SUMMARY: In order to obtain an accurate description of the protein interior, we describe a simple and fast algorithm that measures the depth of each atom in a protein (dpx), defined as its distance (A) from the closest solvent accessible atom. The program reads a PDB file containing the atomic solvent accessibility in…
A mixture of cationic and anionic surfactants has been used as structure-directing agents in the synthesis of mesoscopically ordered silica in the presence of toluene. The preferred interfacial curvature was adjusted by varying the anionic/cationic surfactant molar ratio, which allowed for better control of the solubi…
We consider the problem of heterogeneous nucleation and growth. The system is described by a phase-field model in which the temperature is included through thermal noise. We show that this phase-field approach is suitable to describe homogeneous as well as heterogeneous nucleation starting from several general hypothe…
Abstract General characteristics of the free‐volume theory of diffusion are discussed, and a recent data‐theory comparison involving free‐volume theory is critically evaluated. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 501–507, 2003
Abstract In an attempt to determine the aging behavior of hydroxyl‐terminated polybutadiene‐based composite solid propellants, viscoelastic measurements were used to study the effect of thermal aging on this kind of energetic material. Accelerated‐aging tests at 40, 60, and 80°C were performed for 5000 h. The changes…
Exploring the characterization, thermodynamics and structural, mechanical, thermal and transport behavior of polymers as melts, solutions and solids, this text covers essential concepts and breakthroughs in reactor design and polymer production and processing. It contains modern theories, end-of-chapter problems and r…
Selective catalytic reduction (SCR) of NO with NH 3 in the presence of O 2 takes place over titanium oxide under photoirradiation at low temperature. The active site of TiO 2 is suggested to be the Ti 4+ Lewis acid site. TiO 2 exhibits the weak Lewis acid property. NH 3 is adsorbed easily on the Lewis acid site as com…
A multi-purpose heating attachment designed primarily for X-ray four-circle diffractometers but applicable also for classical powder diffraction is presented. When working in reflection geometry, the air-cooled heating stage allows diffraction studies to be performed on plate-like samples up to 1173 K in the whole ori…
We investigate the degree of grain boundary positional disorder in computer generated fcc nc-Ni samples, as a function of grain size. We find that these grain boundary atoms display a lack of a second peak in the pair distribution function by virtue of their classification, and find further that such a class of atoms…
A series of organogelator salts has been prepared from n -alkylamines by the rapid in situ and isothermal (at room temperature) uptake of a neutral triatomic molecule, CO 2, NO 2, SO 2, or CS 2 . The organogels have been examined by differential scanning calorimetry, optical microscopy, and X-ray diffraction methods.…
A new bidentate “building block”, N,N ‘ -bis(3-pyridylformyl)piperazine (bpfp), was synthesized. X-ray diffraction studies reveal that the piperazine ring in bpfp forms a chairlike structure conformation. bpfp self-assembled into two-dimensional layered rhombohedral grid polymers {[Mn(H 2 O) 2 (SO 4 )(bpfp)](H 2 O) 3…