Materials Literature
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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…
A new tight-binding-bond approach to interatomic forces in liquid aluminum--transition metal (AL-M) alloys is presented. It is shown that the bond order depends strongly on the strength of the pd hybridization in the A-M alloy, leading to nonadditive potentials with a strong preference for the formation of a pair of u…
The static and dynamic magnetic responses of HoPO 4 and ErPO 4 have been studied by means of neutron spectroscopy and magnetic susceptibility measurements. The inelastic neutron scattering spectra exhibit well-defined transitions characteristic of crystal-field excitations of the rare-earth ions. A comparison of the n…
It was found that a high concentration of holes was generated without any post-annealing by boron ion implantation into silicon in the high-dose region of more than 1×1016 cm−2. X-ray photoelectron spectroscopy and Fourier transform infrared absorption spectrum revealed that B12 icosahedra were created just after impl…
The influence of hydrostatic pressure on the temperature dependence of the optical birefringence and ultrasonic velocities is studied in the vicinity of the phase transition temperatures of Cs 2 HgBr 4 , Cs 2 CdBr 4 and Cs 2 HgCl 4 crystals. The new polycritical triple points which separate the normal, incommensurate…
Electrochemically etched silicon wafers can be utilized as transparent host matrices for a variety of luminescent media. Highly efficient (≳1%) photoluminescence across the entire visible range is demonstrated here using organic-dye-activated porous glass layers on Si wafers. Coumarin, xanthene, and oxazine dyes are u…
Researchers have synthesized a compound, [beta]-C[sub 3]N[sub 4], whose properties correspond to those predicted from theory. The synthesis of this compound, which is carbon nitride in the [beta]-Si[sub 3]N[sub 4] structure, shows that theory can point the way toward the creation of materials with hardness comparable…
Pulsed laser ablation of graphite targets combined with an intense, atomic nitrogen source has been used to prepare C-N thin film materials. The average nitrogen content in the films was systematically varied by controlling atomic nitrogen flux. Rutherford backscattering measurements show that up to 40 percent nitroge…