Materials Literature
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The low lying excited states in a system of coupled layers of electrons in a gallium arsenide heterostructure are strongly affected by many-body correlations between the electrons for densities as high as ${\mathit{r}}_{\mathit{s}}$=5. For a layer spacing of less than 100 nm the function Im\ensuremath{\chi}(q,\ensurem…
Quasi-one-dimensional Peierls systems with quantum and thermal lattice fluctuations can be modeled by a Dirac-type equation with a Gaussian-correlated off-diagonal disorder. A powerful new method gives the exact disorder-averaged Green function used to compute the optical conductivity. The strong subgap tail of the co…
It was initially found that CdSb2O6, in which a small part of the Cd ions was substituted with Y ions, has characteristics of a transparent conductor. The electrical conductivity at room temperature of the Y-substituted CdSb2O6 ceramic was larger, by at least 1×100 S cm−1, while that of the nonsubstituted CdSb2O6 was…
Some general relationships have been derived in terms of the unrestricted Hartree-Fock method that define the conditions leading to the breaking of symmetry of one-electron orbitals at oxygen vacancies in oxides of the perovskite family. Numerical calculations of the critical values of relevant parameters have been ca…
The origin of nitrogen acceptor compensation in ZnSe:N has been studied by secondary ion mass spectrometry (SIMS) and infrared absorption (FTIR) measurements. Nitrogen-doped ZnSe layers were grown by atmospheric pressure metalorganic chemical vapor deposition. Ammonia gas was used as a nitrogen source. SIMS analysis h…
We have deposited highly oriented VO2 thin films on R-cut sapphire substrates by the pulsed laser ablation technique. The stabilization of pure VO2 is complicated due to a large number of distinct phases in the vanadium oxide system. As many as 13 different phases ranging from oxygen stoichiometry of V4O to V2O5 can e…
Through thermal treatment of a fluoroaluminosilicate glass codoped with Er3+-Yb3+ at a suitable temperature, microcrystallites were successfully precipitated in the glass matrix but little change was observed in the optical transmission spectra even around the ultraviolet edge, meanwhile the green upconversion lumines…
Photoresist, as one of the most important materials for recording holographic diffraction structures, is treated particularly from the point of view of a control of the development of the surface-relief profile of the grating groove. Primary attention is given to the formation of the desirable profile for the grating…
Abstract Ultrahigh molecular weight polyethylene (UHMWPE) has been irradiated (0–40 Mrad) with a Co 60 source at room temperature under vacuum. The crystallinity has been investigated by differential scanning calorimetry (DSC) and small‐angle X‐ray scattering (SAXS). The mechanical properties have been determined at r…
From the thermodynamic viewpoint the glass transition is a second-order change: there is no latent heat involved, so the entropy varies continuously through the transition. But the transition is not a reversible process. A simulation study of the hard-sphere fluid shows that the statistical entropy, defined in terms o…
To understand better how the packing of side chains within the core influences protein structure and stability, the crystal structures were determined for eight variants of T4 lysozyme, each of which contains three to five substitutions at adjacent interior sites. Concerted main-chain and side-chain displacements, wit…
High-resolution photoemission experiments have been carried out on one-dimensional organic conductors in their normal state. In contrast to usual metals, the spectral function vanishes at the Fermi level and no Fermi edge is detectable. These results are consistent with a Luttinger description and an exponent α of the…
Abstract The precipitation values (PVs) of several organic nonsolvents in polysulfone (PSf)/solvent and polyethersulfone (PESf)/solvent systems were measured in temperatures ranging from 10 to 80°C by the direct titration method and compared with those of water in the same systems. The solvents used were N ‐methyl‐2‐p…
Abstract The color development due to the complex formation of poly(vinyl alcohol) (PVA) with iodine increased with increasing syndiotacticity of PVA. Isotactic PVA showed no color development. The color development of syndiotacticity‐rich PVA film decreased with increasing annealing temperature for films before compl…
The electrical conductivity σ of MgO single crystals shows a sharp increase at 500–800°C, in particular of σsurface, generally attributed to surface contamination. Charge Distribution Analysis (CDA), a new technique providing information on fundamental properties that was previously unavailable, allows for the determi…
Abstract This paper is devoted to the synthesis and characterization of superabsorbent polymers based on acrylic acid. These hydrogels were prepared by carrying the inverse suspension polymerization in an aromatic hydrocarbon. The dispersion is stabilized by the mixture of micromolecular and macromolecular emulsifiers…
Abstract This paper deals with the epoxide treatment of silk fabrics by the pad/batch method. The optimum reaction conditions, i.e., NaOH concentration, and reaction temperature were 2.5 g/L and 30°C, respectively. A weight gain of 8.5% was attained at a reaction time of 6 h. This value slightly increased to 10% after…
High‐pressure infrared absorption spectra of α‐quartz, coesite, stishovite, and SiO 2 glass are consistent with the primary compression mechanism of the initially tetrahedrally bonded phases being the bending of the Si‐O‐Si angle at pressures less than 10–20 GPa. At higher pressures, up to 40 GPa, we observe a decline…
Abstract Chitosan fibers were made by wet spinning of its solution in 2% aqueous acetic acid. The fiber properties were affected by processing conditions, such as spin stretch ratio, coagulation bath composition, and drying conditions. The chitosan fibers were acetylated with acetic anhydride in methanol, producing re…
Abstract Biodegradation of cellulose acetate and cellulose propionate was conclusively established with a naturally derived mixed microbial culture derived from activated sludge and 14 C labeled cellulose esters. Radiolabeled cellulose esters were synthesized with either [1‐ 14 C]‐acetate or [1‐ 14 C]‐propionate and b…