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。
It has been found that X‐ray amorphous silica glasses containing up to 18% carbon can be synthesized using a sol/gel process. In this study, the sols were prepared using four different organometallic precursors—methyl‐, ethyl‐, propyl‐, and phenyltrimethoxysilanes. 1 H NMR, 13 C NMR, and TGA revealed that the methoxy…
In this paper we extend the Van der Waals–Cahn–Hilliard theory of phase transitions to the case of a mixture of n non-interacting fluids. By describing the state of the mixture as given by a vector density function u = (u_1, …, u_n) , the problem consists in studying the asymptotic behaviour as \mathrm{\varepsilon }\r…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTThermal degradation of microbial copolyesters: poly(3-hydroxybutyrate-co-3-hydroxyvalerate) and poly(3-hydroxybutyrate-co-4-hydroxybutyrate)Masao Kunioka and Yoshiharu DoiCite this: Macromolecules 1990, 23, 7, 1933–1936Publication Date (Print):April 1, 1990Publication Histor…
A new methodology in computational micromechanics, dislocation dynamics (DD), is introduced. Dislocation dynamics is developed for examining the dynamic behavior of dislocation distributions in solid materials. Under conditions of externally applied stress, dislocations exhibit glide with a velocity proportional to a…
Abstract Surface oxidation reactions of cobalt, molybdenum and mixed cobalt–molybdenum metals have been investigated using x‐ray photoelectron spectroscopy (XPS). The oxide stoichiometries have been determined from XPS intensity measurements. Such quantification has been important in identifying oxide compositions wit…
Accurate room-temperature structure analyses have been carried out on the two well known structures of cuprite, Cu2O, and corundum, α-Al2O3, using synchrotron radiation, in order to assess the accuracy of single-crystal X-ray diffraction data that can be obtained with such a source. The two compounds were chosen since…
Given our current expertise, and the certain future devel-opments in genetically altering organisms to produce proteins of modified structure and function, the concept of protein engineering is nearing reality. Similarly, our ability to describe and utilize protein structure and to define interactions with ligands has…
The electron-density map of an Si crystal is drawn by the maximum-entropy method (MEM) with 30 structure factors which were determined very accurately on an absolute scale by the Pendellösung method [Saka & Kato (1986). Acta Cryst. A42, 469-478]. It is shown that the following three beneficial points arise from the us…
A review of the observations of indentation‐induced fracture suggests that there is no simple generalization which may be made concerning crack initiation sequences. Here, we investigate the material dependence of the initiation sequence of indentation cracks (cone, radial, median, half‐penny, and lateral) using an in…
Peer reviewed: Yes
The use of the thermoelastic martensitic transformation and its reverse transformation has recently been proposed and demonstrated for several active control ap plications. However, the present constitutive models have lacked several important funda mental concepts that are essential for many of the proposed intellige…
The first conducting polymer was reported in 1977 when Shirakawa, MacDiarmid, Heeger and other coworkers1 discovered that polyacetylene (Fig. 1), an organic polymer and electrical insulator, could be converted into an electrical conductor by absorbing a small amount of iodine. Since then, active research has led to th…
The synthesis of highly conducting polyacetylene in the late seventies inaugurated an era of extensive studies of electronic structure and transport in organic polymers. The recent attainment of conductivities in metallic polyacetylene comparable to that of copper is the outcome of major advances in the theoretical un…
Using simple thermodynamic arguements, it is shown that sharp concentration gradients occurring during diffusive mixing of multilayer composites facilitate amorphization by solid-state reaction by reducing or suppressing the driving force for crystallization \ensuremath{\Delta}${\mathit{G}}_{\mathit{a}\mathit{c}}$. As…
High-resolution x-ray and optical studies were peformed on oriented samples of the recently discovered smectic-${\mathit{A}}^{\mathrm{*}}$ phase. We confirm that this phase exhibits smectic-A layers as well as a macroscopic helical strcucture with the helical axis parallel to the layer planes. Furthermore, we demonstr…
The concept of mean-field rigidity percolation at average coordination number 〈r〉=2.4 in covalently bonded inorganic glasses is shown to be relevant to the liquid-state behavior of glass-forming chalcogenide systems. In particular it correlates with remarkable variations in ``fragility'' and excess heat capacity which…
Abstract Some organic crystalline solids that comprise highly polar molecules and that form non-centrosymmetric crystal structures exhibit second-order nonlinear optical properties and laser-damage thresholds that are potentially superior to those of currently available inorganic systems. This realization has led to a…
Ultrasound causes high-energy chemistry. It does so through the process of acoustic cavitation: the formation, growth and implosive collapse of bubbles in a liquid. During cavitational collapse, intense heating of the bubbles occurs. These localized hot spots have temperatures of roughly 5000 degrees C, pressures of a…
This book deals with the methods of X-ray production at a level which is accessible to advanced undergraduates and researchers who use X-rays. It also discusses the fundamentals of these physical properties from an experimental viewpoint which is not covered in more specialised texts. The book begins with a survey of…
Abstract A mathematical model for simulation of industrial process of solid state polycondensation of poly(ethylene terephthalate) (PET) has been developed. The model eliminates errors evident in the earlier models by proper formulation. The model results have been validated by experimental data in the literature. It…