Materials Literature
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Abstract The ultrasonic degradation of poly(vinyl acetate) (PVAc) solutions was carried out in dioxan at 25, 30, 35, 40, and 45 °C to investigate the effects of the temperature and solution concentration on the rate of degradation. The kinetics of degradation were studied by viscometry. The calculated rate constants i…
ADVERTISEMENT RETURN TO ISSUEPREVNoteThrough-Mask Anodic Patterning of Copper Surfaces and Film Stability in Biological MediaHaixia Dai, Corrine K. Thai, Mehmet Sarikaya, François Baneyx, and Daniel T. SchwartzView Author Information Departments of Chemical Engineering and Materials Science and Engineering, University…
Subunits of the enzymes in the crotonase superfamily form tight trimeric disks. In most members of this protein superfamily these disks assemble further into hexamers. Here we report on the 2.1 A structure of a tight hexameric crystal form of the yeast peroxisomal delta(3)-delta(2)-enoyl-CoA isomerase (Eci1p). A compa…
Electroluminescent (EL) BaAl2S4:Eu devices were prepared with a multilayered phosphor, composed of 10–20 alternating BaS:Eu and Al2S3 thin films and a total phosphor thickness of 300 nm. Depending on evaporation and annealing conditions, pure blue EL was obtained (CIE 1931 color coordinates x=0.120, y=0.098). The use…
Abstract We present results for the effects of a crosslinking agent, cure temperature, and UV flux on the electro‐optical properties of polymer‐dispersed liquid crystal (PDLC) cells. These cells were fabricated using a mixture of a liquid crystal (E8) and an acrylic monomer (CN135). The maximum in the first derivative…
Erbium-doped LaF3 transparent gels have been synthesized by the solution synthesis of metal inorganic precursors. The solid solubility of Er3+ can reach 60 mol %, which is almost double the solubility limit of Er3+ in LaF3 synthesized by the Bridgman technique. A quantitative analysis of the absorption and emission sp…
We have measured the energy and entropy differences between $\ensuremath{\beta}$ and martensitic phases in Cu-Zn and Cu-Zn-Al shape-memory alloy systems which display martensitic transitions in a range of temperatures between 30 K and 130 K. We show that the entropy difference originates in the low-energy ${\mathrm{TA…
Many ferroelectric materials like LiTaO3 and LiNbO3 exhibit peculiar behavior in terms of showing a large discrepancy between experimental and theoretical values of coercive field by the use of Landau–Ginzburg model. If a perturbation is given at zero field, then there is also perturbation or fluctuation in polarizati…
We report the kinetics of Mg reduction of SiO2 at the Cu–Mg/SiO2 interface during vacuum annealing. Annealing supersaturated Cu–Mg films to T>∼400 °C results in the interfacial segregation of Mg and the formation of cubic MgO on the silica side of the interface. At ∼475 °C, the film sheet resistance (RS) increa…
A novel method of preparing multiphase ceramic materials from mixtures of preceramic polymers is described. This method employs the typical immiscibility of polymer blends to prepare two-phase SiC−BN ceramic composites by co-pyrolysis of a mixture of two polymeric precursors, allylhydridopolycarbosilane (AHPCS) (nomin…
Abstract The application of Friedel‐Crafts alkylation reaction to the compatibilization of polypropylene (PP)/polystyrene (PS) blends was assessed. A PP macrocarbocation is chemically bonded to the PS benzene ring by aromatic electrophilic substitution. The graft copolymer formed at the interphase (PP‐ g ‐PS) showed r…
The measurements of thermoelectric powers and current–voltage characteristics were made on the p- and n-type Si specimens which were doped with 0.1 at. % of Al and P, respectively. The apparent Seebeck coefficients Sa of these specimens were measured using various kinds of metal electrodes at cold end and the brass at…
A 0D vanadium borophosphate [Co(en)(3)](2)[V(3)P(3)BO(19)][H(2)PO(4)].4H(2)O (1) and two 1D vanadium oxides [Co(en)(3)][V(3)O(9)].H(2)O (2) and [Co(dien)(2)][V(3)O(9)].H(2)O (3) have been synthesized hydrothermally from the reaction mixture of V(2)O(5)-H(3)PO(4)-H(3)BO(3)-CoCl(2)-R-H(2)O at 110 degrees C (R: en or die…
The p-type (Bi0.25Sb0.75)2Te3 doped with 8 wt % excess Te and 0.3 wt % Se and the n-type Bi2(Te0.94Se0.06)3 doped with 0.08 wt % SbI3, 0.02 wt % Te, and 0.01 wt % CuBr were grown by the Bridgman method at a rate of 6 cm/h. The thermoelectric properties of these specimens were measured before and after annealing, where…
Silicon nanocrystals embedded in a thin oxide layer can be used as charge storage elements in nonvolatile memory devices. The structural characteristics of the nanocrystals and their position in the oxide determine the electrical properties of the devices. In this work, silicon nanocrystals have been formed by ultralo…
Multispin tunneling cross relaxations in an ensemble of weakly coupled Ho3+ ions, mediated by weak anisotropic dipolar interactions, can be evidenced by ac-susceptibility measurements in a high temperature regime. Based on a four-body representation, including the rare-earth nuclear spin, two-ion tunneling mechanisms…
The electric field poling process of nonlinear optical chromophores embedded in an amorphous polymer matrix was studied using molecular dynamics (MD) simulations. Three systems were considered, consisting of a poly(methyl methacrylate) matrix doped with the following chromophores: N, N -dimethyl- p -nitroaniline (DPNA…
This paper studies self-assembly of a rigid oligomer, polyimide (PI) with carboxyl ends, and a proton-accepting polymer poly(4-vinylpyridine) (PVPy) or poly(styrene- co -4-vinylpyridine) (SVP) in solutions. It was found that these rigid/coil polymer pairs could form submicrometer hollow spheres in their common solvent…
Interface and defect structures of Zn–ZnO core–shell nanobelts have been investigated using high-resolution transmission electron microscopy. Most of the nanobelts can be classified into two types from their growth directions: [21̄1̄0] and [0001], with the top/bottom surfaces being (0001) and (21̄1̄0), respectively. T…
Abstract Fibers of PA9‐T, a new semiaromatic polyamide containing a long aliphatic chain, were prepared by melt spinning. As‐spun fibers were subsequently drawn with a CO 2 laser‐heated drawing system at different draw ratios and various drawing velocities. On‐line observations of drawing points deciphered two drawing…