Materials Literature
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We report for the first time on room temperature electroluminescence in the region 1.3–1.7 μm from a strain-adjusted Si6Ge4 superlattice. These results, together with photoluminescence, short-circuit photocurrent spectroscopy, and voltage-intensity and current-intensity measurements indicate that the observed electrol…
Photochemical regulation of in-plane alignment of a nematic liquid crystal is presented. A quartz plate surface was modified with 4-hexyl-4′-hexyloxyazobenzene substituted with triethoxysilyl group through a spacer at the 2′ position to introduce the side-on type azobenzene unit of the surface. A liquid crystal hybrid…
In this paper, it is reported that the electroluminescence (EL) of porous silicon shows a reversible spectral shift as large as 270 nm for an external bias variation of 0.6 V. This electroluminescence is obtained upon cathodic polarization of lightly doped n-type porous silicon in contact with aqueous persulphate solu…
It is found that the thermally activated behavior of nonlinear conduction below the threshold field in thin samples of orthorhombic ${\mathrm{TaS}}_{3}$ vanishes at temperatures below 10 K. Current noise appearing in the low-temperature region indicates that the electric current is transferred by portions of charge wh…
We report the first experimental observation of the commensurate state of the recently discovered helical smectic-C phase. The projection of the reciprocal lattice on the plane perpendicular to the pitch axis consists of a ring of equispaced Bragg spots, as predicted by Renn and Lubensky for the ``twist grain boundary…
We study the selection of the shape and growth velocity of three-dimensional dendritic crystals in cubically anisotropic materials. In the framework of asymptotics beyond all orders we derive the inner boundary-layer equation for the nonaxisymmetric shape correction to the Ivantsov paraboloid shape. The solvability co…
Single quasicrystals of ${\mathrm{Al}}_{70}$${\mathrm{Pd}}_{21}$${\mathrm{Mn}}_{9}$ were plastically deformed by 25% under compression at 750 C. Both these samples as well as control samples of as-grown and heat-treated material were investigated by transmission electron microscopy. It was found that upon deformation…
A stable, non-peptide inhibitor of the protease from type 1 human immunodeficiency virus has been developed, and the stereochemistry of binding defined through crystallographic three-dimensional structure determination. The initial compound, haloperidol, was discovered through computational screening of the Cambridge…
A compound has been synthesized with the formula (rad)(2)Mn(2)[Cu(opba)](3)(DMSO)(2).2H(2)O, where rad(+) is 2-(4-N-methylpyridinium)-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide, opba is orthophenylenebis(oxamato), and DMSO is dimethyl sulfoxide. It consists of two nearly perpendicular graphite-like networks with ed…
Composites of piezoelectric and magnetostrictive materials show a product property called magnetoelectricity which is absent in its constituent phases. The electric and magnetic fields are linked in the composite through the elastic stress-strain fields of the piezoelectric and magnetostrictive phases. Thus an applied…
Oxygen isotope fractionation factors for SiO 2 and Al 2 SiO 5 polymorphs have been calculated by means of the modified increment method. The results suggest that the 18 O is depleted in the high pressure forms (i.e. the more dense phases). The effect of crystal structure on isotopic partitioning in polymorphic phases…
The smartness of a shape-memory material is a consequence of its ability to form a flexible variant structure at one temperature while recognizing only a homogeneous equilibrium at a different temperature. The fine scale morphology or microstructure of this variant structure has a clear role in the macroscopic behavio…
The study of the octahedral Al-Mg series in smectites was conducted using synthesis methods at 200-250°C. All synthesized clays were tetrahedrally charged thus leading to a solid-solution between beidellite and saponite end-members. The TEM chemical microanalyses indicated that the Al-Mg series was continuous between…
Abstract Plasma polymers were deposited on poly (ethylene terephthalate) (PET) substrates using fluorocarbons such as CF 4 , C 2 F 6 , C 3 F 6 , C 4 F 8 , and mixtures thereof with CH 4 . The fluoro‐carbons selected were of saturated structure (CF 4 , C 2 F 6 ), unsaturated structure (C 3 F 6 ), and cyclic structure (…
Solvent Effect on Carboxymethylation of CelluloseThe mixture of water and isopropyl alcohol is the ideal solvent for the preparation of carboxymethyl cellulose (CMC) .lThe effect of the proportion of isopropyl alcohol to water in the solvent on the degree of substitution and viscosity of the CMC product has been repor…
Three different photon correlation methods are used to obtain the dynamic structure factor of nonergodic samples, such as glasses or gels. These methods are compared in terms of their statistical accuracies and applicabilities. The scheme suggested by Pusey and van Megen [Phys. A 157, 705 (1989)] appears to be the mos…
Abstract Chitosan fibers were treated with aqueous solutions of CuSO 4 and ZnSO 4 for different periods of time to prepare samples containing different levels of metal‐ion contents. The effect of metal ions on the tensile properties of chitosan fibers was studied. It was found that after chelation of metal ions the ch…
Abstract The elastic modulus of polyepichlorohydrin (PECH) filled with glass beads and wollastonite was studied. It was found that the elastic modulus of the composites depends not only on the volume fraction of the fillers but also on their size. Percolation theory was used to explain the experimental results. © 1993…
Abstract The dependencies of the notched Izod impact toughness of HDPE / CaCO 3 blends on CaCO 3 particle concentration and particle size are analyzed. It was found that the notched Izod impact strength ( S ) of HDPE / CaCO 3 blends depends discontinuously on CaCO 3 particle concentration. A brittle‐ductile transition…
Optical absorption and photoluminescence spectra in the range 1.2–2.2 eV have been measured in free-standing films of porous Si under hydrostatic pressures up to 6.4 GPa at room temperature. The absorption rises nearly exponentially in the low energy region. Under pressure, the whole spectrum shifts toward lower energ…