Materials Literature
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Abstract The effects of ultraviolet (UV) radiation and thermal annealing on the optical and mechanical properties of polyvinyl alcohol (PVA) were studied. Pure PVA samples were prepared by casting technique. Xenon arc lamp was used to irradiate the sample. The irradiated PVA sample was heated at 150°C for 2 h. The opt…
Carbon single-wall nanotubes (SWNTs) grow efficiently from methane on alumina-supported metal catalysts within a fairly narrow temperature window from 680 to 850 °C. An abrupt onset in SWNT growth occurs at the low temperature side of the window, and SWNTs produced at these lower temperatures appear to be relatively f…
We use steady-shear rheology to study the shear-disordering phenomenon in block copolymers in the body-centered-cubic (bcc) mesophase. Polystyrene−polyisoprene and polystyrene−poly(ethylene- alt -propylene) diblock, triblock, and starblock systems of varying molecular weight and composition were studied in the melt an…
Most studies of self-assembled systems reveal that the highest order is associated with equilibrium states of the system. By systematically studying metal decoration of diblock copolymer templates, I show that a high degree of order can arise under strongly nonequilibrium conditions. Under a wide range of conditions,…
Flash-cooling and annealing of macromolecular crystals have been investigated using in situ X-ray imaging, diffraction-peak lineshape measurements and conventional crystallographic diffraction. The dominant mechanisms by which flash-cooling creates disorder are suggested and a fixed-temperature annealing protocol for…
Amorphous tungsten oxide has been prepared by ultrasound irradiation of a solution of tungsten hexacarbonyl W(CO)6 in diphenylmethane (DPhM) in the presence of an Ar (80%)–O2 (20%) gaseous mixture at 90 °C. Heating this amorphous powder at 550 °C under Ar yields snowflake-like dendritic particles consisting of a mixtu…
Pyrococcus furiosus maltodextrin-binding protein readily forms large orthorhombic crystals that diffract to high resolution. This protein was used as a model system to investigate the influence of five short affinity tags (His(6), Arg(5), Strep tag II, FLAG tag and the biotin acceptor peptide) on the formation of prot…
We have investigated the effect of electron-phonon scattering in a series of n-type nickel-doped ${\mathrm{CoSb}}_{3}$ skutterudite materials. Samples were polycrystalline of the form ${\mathrm{Co}}_{1\ensuremath{-}x}{\mathrm{Ni}}_{x}{\mathrm{Sb}}_{3}$ with $x=0,$ 0.001, 0.003, 0.005, 0.0075, and 0.01. The lattice the…
Examples of phasing macromolecular crystal structures based on single-wavelength anomalous dispersion (SAD) show that this approach is more powerful and may have more general application in structural biology than was anticipated. Better data-collection facilities and cryogenic techniques, coupled with powerful progra…
A novel method for conjugating porphyrins and related molecules to proteins has been developed. The method, which involves synthesizing porphyrins, chlorins, and bacteriochlorins bearing a single amine-reactive isothiocyanate group represents a facile system for protein labeling with these photoactive species. Problem…
Abstract Poly(lactic acid) (PLA) and wheat starch are biodegradable polymers derived from renewable sources. A previous study showed that thermally blending starch and PLA in the presence of methylenediphenyl diisocyanate (MDI) enhanced the mechanical properties of the blends. In this work, blends of PLA with various…
A quantitative description of the configurational part of the total energy of metallic alloys with substantial atomic size difference cannot be achieved in the atomic sphere approximation: It needs to be corrected at least for the multipole moment interactions in the Madelung part of the one-electron potential and ene…
We present a first-principles numerical implementation of Landauer formalism for electrical transport in nanostructures characterized down to the atomic level. The novelty and interest of our method lies essentially on two facts. First of all, it makes use of the versatile Gaussian98 code, which is widely used within…
We have used the locally self-consistent Green's function (LSGF) method in supercell calculations to establish the distribution of the net charges assigned to the atomic spheres of the alloy components in metallic alloys with different compositions and degrees of order. This allows us to determine the Madelung potenti…
The mechanisms of the magnetization switching of magnetic multilayers driven by a current are studied by including exchange interaction between local moments and spin accumulation of conduction electrons. It is found that this exchange interaction leads to two additional terms in the Landau-Lifshitz-Gilbert equation:…
We employ a simple model to describe the phase behavior of 4He and Ar in a hypothetical porous material consisting of a regular array of infinitely long, solid, parallel cylinders. We find that high porosity geometries exhibit two transitions: from vapor to film and from film to capillary condensed liquid. At low poro…
It is generally argued that for high-temperature superconductors (HTS) to be cost-competitive in power applications, the wire will have to sell for about $10 per kiloampere meter ($10/kAm) for operation at 77 K (e.g., NbTi costs around $1/kAm and Nb3Sn around $8, each at 4.2 K). Given what is already known about the c…
The interlayer spin correlations in the magnetic/non-magnetic semiconductor superlattices are reviewed. The experimental evidences of interlayer exchange coupling in different all-semiconductor structures, based on neutronographic and magnetic studies, are presented. A tight-binding model is used to explain interactio…
We present a single-orbital double-exchange model, coupled with cooperative phonons (the so called breathing-modes of the oxygen octahedra in manganites). The model is studied with Monte Carlo simulations. For a finite range of doping and coupling constants, a first-order Metal-Insulator phase transition is found, tha…
Mesoporous titania with BET surface area over 1200 m 2 /g - 1 was synthesized by primary amine templating. Dodecyl-, tetradecyl-, and hexadecylamines gave intense XRD patterns with narrow pore-size distributions in which the most probable diameter changed according to the carbon chain length. Thermal treatment was nec…