Materials Literature
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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…
Fluorescence intensity enhancement has been studied for several coverages (10-3 to 1 monolayer) of Rhodamine 6G separated from a silver island film by quartz spacer layers of varying thickness. When the dye film is brought into the proximity of the island film support, a first enhancement maximum is observed at ≈ 60 n…
The use of molecular self-assembly to fabricate microstructures suitable for advanced material development is described. Templating techniques that transform biomolecular self-assemblies into rugged and stable nano- and microstructures are described. By using a lipid-based microcylinder (tubule) as a paradigm, the pat…
The recursion and path-integral methods are applied to analytically study the electronic structure of a neutral $C_{60}$ molecule. We employ a tight-binding Hamiltonian which considers both the $s$ and $p$ valence electrons of carbon. From the recursion method, we obtain closed-form {\it analytic} expressions for the…
We study the electronic states of giant single-shell and the recently discovered nested multi-shell carbon fullerenes within the tight-binding approximation. We use two different approaches, one based on iterations and the other on symmetry, to obtain the $π$-state energy spectra of large fullerene cages: $C_{240}$, $…
Abstract A window on modern crystallography presents contributions given at the Vesprém School on Crystallographic Computing June 1992, Balatonfúred, Hungary. Nineteen review articles cover subjects of topical interest in the state of crystallographic software. The application to crystallography of windowing technique…
Abstract Shear band localizations are studied using a band model involving two polycrystalline aggregates; one representing the material inside the potential band and the other the material outside. Each of these aggregates is assumed to be homogeneously deformed and conditions of compatibility and equilibrium are enf…
We study the entropy of dimers on a semi-infinite M*N square lattice (N to infinity ) with lattice interaction energy per dimer mu 1 and nearest-neighbour interaction energy mu 2 . Numerical computations based on recursive transfer matrices show that for M=1, 2, 3, 4 and 5, and under certain conditions, the constant-…
For each of the compounds MnTi 2 , FeTi 2 , CoTi 2 , NiTi 2 , PdTi 2 , PtTi 2 and CuTi 2 , the differences between the total energies of the compounds in the MoPt 2 -, MoSi 2 - and NiTi 2 -type crystal structures are calculated. Trends of structural energy differences are analysed by performing 'frozen-potential' ener…
We report the first direct measurements of spin/orbital magnetization ratios in a ferromagnetic material using X-ray diffraction. The simple technique, based on diffraction of elliptically polarized white synchrotron radiation, produces spin/orbital ratios that are independent of the precise photon polarization. Resul…
A one-dimensional microhole array with high-aspect ratio was successfully obtained using anodic oxidation of an aluminum oxide/aluminum/glass structure. This process allows the fabrication of an array of microholes less than 1000 Å diameter without any exposure mask or resist, and the size of the array can be controll…
The growth behavior of diamond films synthesized from halomethane reactants is studied in a hot-filament chemical vapor deposition reactor. The growth characteristics of methane and several chloromethane reactants (CH2Cl2, CHCl3, and CCl4) are examined over a number of reactant concentrations, substrate temperatures (…
We have measured the thermal conductivity κ of single crystals of hexagonal silicon carbide (6H-SiC) of two different electron densities n. The densities are low such that virtually all of the heat is conducted by lattice vibrations. At low temperatures the thermal conductivity of both samples varies as T2 and scales…
An O(N) and rapidly convergent method for calculating the bond order potential and forces for the atomistic simulation of covalent systems is described. A derivation of a novel many-atom expansion, which allows the Green's functions, not only to handle the symmetry problem correctly but also to retrieve equivalence be…
Currently, the materials with the highest thermoelectric figure of merit (ZT) are one-band materials. The presence of both electrons and holes lowers ZT, so two-band materials such as semimetals are not useful thermoelectric materials. However, by preparing these materials in the form of two-dimensional quantum-well s…
As meta1-air batteries have high energy(lensities they are attractive as a power source of electric vehicles1)Howeverone has to overcome various difnculties to realize practical batteries of this type
Abstract Oxidation induction time (OIT), as measured by differential scanning calorimetry, is useful in assessing the extent of degradation in polymeric materials. Values of OIT for typical EPR and XLPE polymer insulation materials used for electric cable insulation in nuclear power plants were measured as a function…
Abstract A kinetic model has been developed on the basis of reaction mechanisms proposed for the anhydride curing of diepoxides, using tertiary amine as catalyst. The model has been tested for the cure reaction of a diglycidylester model compound, bis‐(2,3‐epoxypropyl)‐1,3‐benzenedicarboxylate, with hexahydrophthalic…