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。
Polycaprolactone-graft-maleic anhydride (PCL-g-MA) copolymer was prepared by grafting maleic anhydride onto PCL in a batch mixer and in an extruder using dicumyl peroxide as the initiator. The graft content was determined with the volumetric method by converting the anhydride functions to acid groups and then titratin…
Volume recovery measurements have been used to study the physical aging behavior of a polyetherimide. Isothermal aging temperatures near Tg were studied with aging times ranging up to several days. The volume decreases during physical aging and levels off at equilibrium. For comparison purposes, the data are normalize…
The standard parameters controlling AB diblock copolymer phase behavior are χN and fA, where χ is an A-B segment interaction parameter, N is the overall degree of polymerization, and fA is the volume fraction of the A block. Recently, it has been recognized that the ratio of the A and B statistical segment lengths αA/…
The x-ray crystal structure of the serine protease subtilisin Carlsberg in anhydrous dioxane has been determined to 2.6-A resolution. The enzyme structure is found to be nearly indistinguishable from the structures previously determined in water and acetonitrile. Small changes in the side-chain conformations between t…
The teeth of sea urchins comprise a variety of different structural entities, all of which are composed of magnesium-bearing calcite together with a small amount of organic material. The teeth are worn down continuously, but in such a way that they remain sharp and functional. Here we describe aspects of the structura…
Differential, integrated elastic and momentum transfer cross sections have been calculated for the scattering of electrons by and OCS molecules in the energy range 100 - 1000 eV and total cross sections over a wide incident energy range 100 - 4000 eV. A relatively simple approach, namely the independent atom model (IA…
An ab initio based tight-binding molecular-dynamics method is used to generate 60 amorphous carbon nitride structures, $a$-CN, with various stoichiometries and densities, providing the first atomic level insight into the chemical bonding properties of these materials. Focusing on high densities, we observe clear trend…
The magnetization of novel supramolecular grid structures consisting of four bis(bipyridyl)-pyrimidine ligands and four ${\mathrm{Co}}^{2+}$ ions was measured. We provide evidence for an antiferromagnetic coupling of the ${\mathrm{Co}}^{2+}$ spins. Investigations of microcrystals, powders, and solutions with the mean…
High-resolution neutron powder diffractometry has been used to characterize the structural phase transition which occurs in at . The change in lattice parameters of the trigonal unit cell as a function of temperature, observed in the range from ambient to , shows that the transition from the polar space group to the n…
Cu metallization of AlN substrates was performed using a nonaqueous, electroless, alcohol based approach known as the polyol method. The concentration of Cu2O in the film depended on the orientation of the substrates during deposition. This approach is very attractive for metallizing electronic substrates which are su…
We report on thin-film microstrip lines (TFMSLs) fabricated on low-resistivity Si with polymerized cyclotene as the dielectric between signal and ground conductor, all on top of the wafer. Electro-optic high-frequency characterization of the TFMSLs reveals negligible modal dispersion up to the highest frequencies of 1…
We report the observation of optically pumped lasing in ZnO at room temperature. Thin films of ZnO were grown by plasma-enhanced molecular beam epitaxy on (0001) sapphire substrates. Laser cavities formed by cleaving were found to lase at a threshold excitation intensity of 240 kW cm−2. We believe these results demons…
A significant part of micro-optical technology is based on the use of diffractive structures to control the amplitude, the phase, or the state of polarization of an optical field. In diffractive micro-optics, periodic structures (gratings) play a central role, because most diffractive elements may be treated as gratin…
The effects of an insoluble surfactant on the motion of a drop or bubble as it is driven by a pressure gradient through a capillary tube is investigated numerically. We find that a drop in a straight capillary tube can either approach a steady-state shape or develop a re-entrant cavity at its rear. For a gas bubble mo…
Composites of a polypyrrole (PPy) and poly(vinyl chloride-vinyl acetate) copolymer (PVC-PVA) were prepared both chemically and electrochemically. An insulating polymer was retained in the blend and the thermal stability of the polymer was enhanced by polymerizing pyrrole into the host matrix in both cases. The composi…
The dynamics of a spreading liquid body are dictated by the interface shape and flow field very near the moving contact line. The interface shape and flow field have been described by asymptotic models in the limit of small capillary number, Ca . Previous work established the validity and limitations of these models o…
Unmodified blends of two thermoplastic polyurethanes (TPU) and six polyolefines were used to study the influence of the component viscosities on the blend morphology and mechanical properties. Blends were produced by melt mixing using a twin screw extruder. Interactions between the blend components could not be detect…
A series of eight thermoplastic polyurethane elastomers were synthesized from 4,4′-methylene diphenyl diisocyanate (MDI) and 1,4-butanediol (BDO) chain extender, with poly(hexamethylene oxide) (PHMO) macrodiol soft segments. The PHMO molecular weights employed ranged from 433 g/mol to 1180 g/mol. All materials contain…
We report a novel practical method to determine exchange parameters by using experimental susceptibility data in a relatively narrow temperature region and a low order high-temperature-expansion equation. This method is applied to a square lattice and a CaV_4O_9-type lattice, and its accuracy is discussed.
In this paper, we develop a rigorous formulation of the local stress field. This approach can be used in conjuction with any first-principles method to study stress fields in complex bonded systems. In particular we investigate the induced stress fields resulting from homogeneous deformations for tetragonal PbTiO_3 an…