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 The hydrolytic depolymerization of molten PET in excess water was studied using a 2 L stirred pressure reactor at temperatures of 250, 265, and 280°C. Rate constants for hydrolysis are calculated from the initial rate data. At initial water: PET charge ratios (w/w) exceeding 5.1, essentially complete depolyme…
The π-electron states of carbon nanotubes (CN's) in magnetic fields are calculated in the effective-mass theory. A sensitive change of CN from metal to semiconductor depending on its structure is well reproduced. The band gap is inversely proportional to the tube diameter and exhibits a drastic change as a function of…
Electromigration is an important concern in very large scale integrated circuits. In narrow, confined metal interconnects used at the chip level, the electromigration flux is resisted by the evolution of mechanical stresses in the interconnects. Solutions for the differential equation governing the evolution of back s…
A 16-residue peptide [(Ala-Glu-Ala-Glu-Ala-Lys-Ala-Lys)2] has a characteristic beta-sheet circular dichroism spectrum in water. Upon the addition of salt, the peptide spontaneously assembles to form a macroscopic membrane. The membrane does not dissolve in heat or in acidic or alkaline solutions, nor does it dissolve…
Monte Carlo simulations of electron scattering in silver have been performed at 6 and 20 keV to investigate the relation between electron transport, backscattering and depth distribution of characteristic X-ray production of tracer elements. The simulation models used combine the use of elastic cross sections, either…
For the determination of the strain in structures with only one or two layers on a substrate, rocking curve measurements are sufficient to provide values for the perpendicular and in-plane lattice mismatch as well as the relative orientation of the layer. The author presents new relations for the interpretation of the…
The effects of radiation on polymer materials is an area of rapidly increasing interest. Several high technology industries require specialty polymers that exhibit a specific response upon exposure to radiation. For instance, the electronics industry requires materials that undergo radiation induced scission or crossl…
The effects of radiation on polymer materials is an area of rapidly increasing interest. Several high technology industries require specialty polymers that exhibit a specific response upon exposure to radiation. For instance, the electronics industry requires materials that undergo radiation induced scission or crossl…
Porous silicon layers prepared by anodic dissolutions of silicon wafers in aqueous HF solutions reveal either crystalline phase or intermediate phase between microcrystalline and amorphous phases, depending on the anodization conditions. The configurations of hydrogen and oxygen atoms near the surface of microstructur…
X-ray absorption spectroscopy has been applied to the study of local structural changes in amorphous tungsten trioxide thin films under colouration in an acid aqueous solution. It has been found that the formation of W 5+ coloured centres is accompanied by the appearance of local deformations around them. It is shown…
Compounds in the series Sm 2 Fe 17-x Al x have been investigated. Samples with x=0, 1, 2, 3 and 4 have been shown to be single phased with the Th 2 Zn 17 structure. The Curie temperature is found to increase from T C =391K for the x=0 sample to T C =471 K for the x=3 sample. Further substitution of Al for Fe decreased…
Variable angle spectroscopic ellipsometry over the photon energy (E) range 1.5≤E≤5.5 eV has been used to study the structure and optical properties of thin (<400 Å) laser-deposited boron nitride films grown on Si(100). The data are interpreted to indicate that initially the film grows next to the substrate in t…
The long-time self-diffusion coefficient of a colloidal fluid interacting via a Yukawa potential and obeying Brownian dynamics is calculated by computer simulations for different parameters of the Yukawa potential over a broad range of densities. As two extreme cases, the hard sphere and the unscreened Coulomb interac…
The conformation of a main-chain liquid crystalline polyester in its oriented nematic phase has been determined by small-angle neutron scattering. The data are fitted by a model of rigid cylinder with orientational fluctuations. For a low degree of polymerization (\ensuremath{\sim}9) the chain is almost completely elo…
A virgin sample of polycrystalline (C10H21NH3)2ZnCl4 shows two phase transitions, at 284 K and 363 K. In the low-temperature phase threefold reorientations of methyl and NH3 groups dominate the nuclear magnetic resonance relaxation results. The motion of the NH3 groups can be described as a three-fold jump among three…
We have used time-resolved electron-paramagnetic resonance (EPR) spectroscopy to investigate the triplet energy transfer in various covalently linked porphyrin dimers. For all these dimers the fine structure parameters are rather similar to the monomer values; thus according to the field-swept EPR spectra the triplet…
Scalar diffraction theory and electromagnetic vector theory are compared by analyzing plane-wave scattering by a perfectly conducting, rectangular-grooved grating. General field solutions for arbitrary angles of incidence are derived by using scalar and vector theories. Diffraction efficiencies for the scalar and the…
Explicit expressions for the Frank elasticity coefficients of nematic liquid crystals are obtained using the model of perfect local orientational order. The use of the density functional approach enables one to express the results in terms of the direct correlation function for a liquid of perfectly aligned particles.…
Abstract Some mechanical and electrical properties of the BPDA/ODA/PDA polyimide film prepared on mylar followed by various cure schedules have been studied. It has been found by FTIR that the imidization reaches its maximum after a 200°C cure schedule for this polyimide. However, the optimum condition of curing is a…
Abstract The effect of syndiotactivity of poly(vinyl alcohol) (PVA) both on the formation and thermal stability of the complex formed in the amorphous phase of PVA films is investigated, and then a model of the complex is presented. The amount of the complex formed in syndiotacticity‐rich PVA is much larger than that…