Materials Literature
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The photoluminescence (PL) spectra of the undoped ZnO films deposited on Si substrates by dc reactive sputtering have been studied. There are two emission peaks, centered at 3.18 eV (UV) and 2.38 eV (green). The variation of these peak intensities and that of the I–V properties of the ZnO/Si heterojunctions were inves…
ADVERTISEMENT RETURN TO ISSUEPREVCommunication to the...Communication to the EditorNEXTChemoselective Ring-Opening Polymerization of a Lactone Having exo-Methylene Group with Lipase CatalysisHiroshi Uyama, Shiro Kobayashi, Masatake Morita, Shigeki Habaue, and Yoshio OkamotoView Author Information Department of Materia…
The temperature dependence of the DC resistivity of silver quantum dot self-assembled 2D Langmuir monolayers was obtained. The films exhibit a metallic-like resistance at high temperatures (above 200 K), and a thermally activated mechanism at intermediate temperatures (60−200 K) which strongly supports the model of a…
Triblock polymers, poly(ethylene oxide-b-propylene oxide-b-ethylene oxide) (PEO-b-PPO-b-PEO), are used as molecular templates in poly(methyl silsesquioxane) (MSQ) matrixes to fabricate nanoporous organosilicates. The triblock copolymers microphase-separate into nanometer domains as the MSQ matrix becomes increasingly…
A two-dimensional self-consistent-field lattice model incorporating the rotational isomeric state scheme to account for chain rigidity was developed to study the phase diagram of rod−coil diblock copolymer melts. Several morphologies such as lamella, zigzag lamella, elliptical cross-sectional cylinders, and hexagonall…
ADVERTISEMENT RETURN TO ISSUEPREVCommunication to the...Communication to the EditorNEXTDivergent Synthesis of Dendronized Poly(p-hydroxystyrene)Scott M. Grayson and Jean M. J. FréchetView Author Information Center for New Directions in Organic Synthesis,† Department of Chemistry, University of California, Berkeley, Ca…
A novel, wet chemical approach is reported for the facile synthesis of silver nanowires with diameters in the range of 20−40 nm in aqueous solutions of a double-hydrophilic block copolymer (DHBC) PEO-b-PMAA. Investigation of the time-dependent formation of the silver nanowires revealed that they were produced through…
The ramifications of changing molecular geometry in a series of all-aromatic liquid crystals derived from p -quinquephenyl are reported. Substituting heterocyclic rings such as thiophene, oxadiazole, oxazole, or 1,3-phenylene into the p -quinquephenylene core affects molecular shape changes via the substituent's exocy…
We derive the spin-wave dynamics of a magnetic material from the time-dependent spin density functional theory in the linear response regime. The equation of motion for the magnetization includes, besides the static spin stiffness, a "Berry curvature" correction and a damping term. A gradient expansion scheme based on…
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Nitrogen-doped carbon nanotubes have been synthesized using pyrolysis and characterized by scanning tunneling spectroscopy and transmission electron microscopy. The doped nanotubes are all metallic and exhibit strong electron donor states near the Fermi level. Using tight-binding and ab initio calculations, we observe…
Results of first-principles electronic structure calculations on the low-temperature monoclinic phase of the ferromagnetic perovskite BiMnO 3 [Atou et al. J. Solid State Chem . 1999, 145, 639] are presented. In agreement with experiments, the calculations obtain an insulating ferromagnetic ground state for this materi…
The thermal stability of organically modified layered silicate (OLS) plays a key role in the synthesis and processing of polymer-layered silicate (PLS) nanocomposites. The nonoxidative thermal degradation of montmorillonite and alkyl quaternary ammonium-modified montmorillonite were examined using conventional and hig…
We have studied the transport properties of a cholesteric liquid crystal by molecular dynamics simulation. The molecules consist of six soft ellipsoids of revolution, the axes of which are perpendicular to the line connecting their centres of symmetry. The angle between the symmetry axes of two adjacent ellipsoids is…
In this communication we report initial results of studies on x-ray and VUV excited luminescence of YAP and YAG crystals activated with Pr<SUP>3+</SUP> and YAP activated with Ce<SUP>3+</SUP>. Excitation and luminescence spectra of Pr<SUP>3+</SUP> and Ce<SUP>3+</SUP> d-f and Pr<SUP>3+</SUP> f-f emissions and luminescen…
Abstract A series of fully aromatic copolyesters based on p ‐acetoxybenzoic acid ( p ‐ABA), hydroquinone diacetate (HQDA), terephthalic acid (TPA), and m ‐acetoxybenzoic acid ( m ‐ABA) were prepared by a modified melt‐polycondensation reaction. The copolyesters were characterized by DSC, thermogravimetric analysis, 1…
Aproaches for imparting antimicrobial activity to polymeric materials have evolved from ancient practices to eclectic, modern strategies. The mechanisms by which microbes attach to polymeric surfaces and acquire resistance to antimicrobial agents are critically reviewed. Representative microorganisms (primarily bacter…
Abstract The charge distribution in samples under direct current electrical field was measured by the pulsed electro‐acoustic method, which showed that the space charges were greatly decreased and field distribution tended to be uniform in low‐density polyethylene (LDPE) by adding 0.3 wt % bis‐( p ‐ethylbenzylidene)so…
The two photon absorption coefficient and third order nonlinear optical susceptibility of ZnSe crystals were investigated using the transmission and degenerate four wave mixing methods. The experimental results show that imaginary part of third order nonlinear optical susceptibility decrease with increase of free carr…
Abstract A novel hyperbranched poly(glycidol) (HPG) was prepared and characterized. The synthesized HPG was used as a substrate of a polymer electrolyte. The ionic conductivity of a blend of HPG, polyurethane (PU), and salt was studied. The ionic conductivity of HPG/PU/LiClO 4 was about 6.6 × 10 −6 S · cm −1 at 20 °C…