Materials Literature
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Transition metals (Pt, Pd, Rh, Cr, etc.) are widely used as catalysts on \ensuremath{\gamma}- and \ensuremath{\eta}-alumina, two phases of ${\mathrm{Al}}_{2}{\mathrm{O}}_{3},$ but the catalytic activity of Cr on \ensuremath{\gamma}-alumina degrades rapidly. We report density-functional calculations that trace the orig…
Abstract A mathematical model to describe the molecular weight and polydispersity index ( Q ) in poly( L ‐lactide) (PLLA) thermal degradation has been developed. Based on the random chain scission mechanism, effects of temperature and time on the molecular weight and polydispersity index are included in this model. It…
Abstract In the extrusion manufacture of starch‐based thermoplastics, such as biodegradable packaging materials, glycerol is an effective additive as a plasticiser, that is, to diminish the brittle nature of the product and provide the desired extent of flexibility. However, the addition of glycerol may also affect th…
We have performed dielectric loss measurements at 1 kHz on thin films of isotactic poly(methyl methacrylate). A key distinction of our studies is that the samples measured were supported films with one free surface rather than films that have metallic electrodes covering both surfaces. This unique sample geometry allo…
BACKGROUND: It has been found recently that the MRI contrast agent superparamagnetic iron oxide (SPIO) localizes to aortic atherosclerotic plaques. We therefore asked whether SPIO might be used to monitor monocyte recruitment into aortic atherosclerotic plaques. METHODS AND RESULTS: Eleven female apo E knockout (K/O)…
First measurements of oxygen grain boundary diffusion coefficients in nanocrystalline yttria-doped ZrO(2) (n-ZrO(2).6.9 mol % Y(2)O(3)) are presented. The (18)O diffusion profiles measured by secondary ion mass spectroscopy are much deeper in the nanocrystalline specimens than in single crystals. An oxygen diffusivity…
Large-scale zinc oxide (ZnO) nanowires were grown via a simple chemical reaction involving water vapour. Electron microscopy observations reveal that the ZnO nanowires are single crystalline and grow along the c -axis ([001]) direction. Room temperature photoluminescence measurements show a striking blue emission at 4…
We report an x-ray absorption spectroscopic (XAS) study on thin films of ${\mathrm{La}}_{0.7}{\mathrm{Ce}}_{0.3}{\mathrm{MnO}}_{3}.$ The measurements clearly show that the cerium is in the Ce(IV) valence state, and that the manganese is present in a mixture of ${\mathrm{Mn}}^{2+}$ and ${\mathrm{Mn}}^{3+}$ valence stat…
The theory of Raman scattering by the electron--phonon coupled system in metals and heavily doped semiconductors is developed taking into account the Coulomb screening and the electron--phonon deformation interaction. The Boltzmann equation for carriers is applied. Phonon frequencies and optic coupling constants are r…
We have made a magnetic characterization of Nd0.5Sr0.5MnO3, Nd0.5Ca0.5MnO3, Sm0.5Ca0.5MnO3, Dy0.5Ca0.5MnO3 and Ho0.5Ca0.5MnO3 polycrystalline samples. Ferromagnetic, antiferromagnetic and charge ordering transitions in our samples agree with previous reports. We also report specific heat measurements with applied magn…
We find that the damping of micromechanical cantilevers is sensitive to the relaxation dynamics of paramagnetic ions contained within the levers. We measure cantilevers containing paramagnetic Mn ions as a function of temperature, magnetic field, and the vibrational mode of the lever and find that the levers damping i…
Well-defined “single” Pd(0) atoms were encapsulated in Pd-mediated multiporphyrin arrays and used as a catalyst. Compared with the Pd(0) nanoparticles prepared from dilute K 2 PdCl 4 solution, the encapsulated Pd(0) atoms showed much higher catalytic activity for photoinduced hydrogen evolution.
The structural and compositional evolution of four members of the ANbWO(6) (A = NH4+, Rb+, H+, K+) defect pyrochlore family have been studied as a function of pressure up to 7 GPa, using a diamond anvil cell and monochromatic synchrotron X-ray powder diffraction. In response to increasing hydrostatic pressure, NH(4)Nb…
The Ag nanorods and nanofibers have been synthesized in sodium bis(2-ethylhexyl) sulfosuccinate (AOT)/isooctane reverse micelles with the aid of low-intensity ultrasonication. The TEM results show that only spherical silver nanoparticles can be obtained from the reverse micelles in the absence of ultrasonication where…
The present report undertakes a challenge of general interest in supramolecular chemistry: the achievement of helical organizations with controlled structure. To achieve this target we considered the possibility of inducing supramolecular chirality using molecules that were designed to organize into columnar mesophase…
Glutaryl 7-aminocephalosporanic acid acylase (GCA, EC 3.5.1.11) is a member of N-terminal nucleophile (Ntn) hydrolases. The native enzyme is an (alpha beta)(2) heterotetramer originated from an enzymatically inactive precursor of a single polypeptide. The activation of precursor GCA consists of primary and secondary a…
ADVERTISEMENT RETURN TO ISSUEPREVNoteNEXTFerrocene-Containing Polyelectrolyte Multilayer Films: Effects of Electrochemically Inactive Surface Layers on the Redox PropertiesAihua Liu and Jun-ichi AnzaiView Author Information Graduate School of Pharmaceutical Sciences, Tohoku University, Aramaki, Aoba-ku, Sendai 980-857…
Combinatorial methods are utilized to study the influence of film thickness (13 nm < h < 120 nm) and crystallization temperature (131 °C < T x < 193 °C) on the crystallization of isotactic polystyrene. Films with continuous gradients in film thickness were prepared by flow coating, crystallized on an orthogonal temper…
Controllable assembly of ordered nanoscale structural units in geometrically well-defined configurations is essential for building integrated nanoscale systems. Here, we describe a powerful method to simultaneously grow aligned carbon nanotube bundles in multiple, predetermined orientations on planar substrates to bui…
We describe a convenient, one-step sol−gel route to composite polymeric organic−inorganic particles. The synthesis is based on performing the sol−gel polycondensation within a surfactant-stabilized emulsion of a solution of a polymer polystyrene of various molecular weights in tetraethoxysilane, with or without toluen…