Materials Literature
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The kinetics of NO reduction over wheat straw char in the presence and absence of CO was investigated in a laboratory scale fixed bed quartz reactor. Experiments were performed with char from both the raw straw and from washed straw. The wash procedure removed most of the content of potassium and other catalytic speci…
Abstract To prepare novel polyimides with enhanced thermal stability and high solubility in common organic solvents, diamine monomers, 4‐aryl‐2,6 bis‐(4‐amino phenyl)pyridine, were introduced. The diamines were reacted with three different conventional aromatic dianhydrides including pyromellitic dianhydride, benzophe…
The calculations on magnetic exchange interaction of Cl 3 FeOFeCl 3 2- and the related modeling compounds were performed by using the density functional theory coupling the broken symmetry approach. The calculated results show the absence of a direct Cl 3 Fe---FeCl 3 magnetic coupling and the effect of the terminal Cl…
The thermal reaction of ethyl undecylenate with a hydrogen-terminated porous silicon surface takes place at 85 °C to yield an organic monolayer covalently attached to the surface through Si−C bonds. The presence of traces of water in ethyl undecylenate induces a partial oxidation of the surface and leads to a surface…
ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTMetal Nanowire Formation Using Mo3Se3- as Reducing and Sacrificing TemplatesJae Hee Song, Yiying Wu, Benjamin Messer, Hannes Kind, and Peidong YangView Author Information Department of Chemistry, University of California Materials Science Division, Lawrence Berkeley Na…
The influence of the silica source on the morphology and the internal architecture of mesoporous fibers was investigated. It was found in all cases studied that the hexagonally packed pores are oriented in a circular manner around the fiber axis. However, the kinetics of fiber formation and the product distribution va…
We report on a general method for the calculation of the frequency-dependent optical response of clusters based upon time-dependent density functional theory (TDDFT). The implementation is done using explicit propagation in the time domain and a self-consistent program that uses a linear combination of atomic orbitals…
The generation of harmonics of the voltage response is considered when an AC current is applied through a superconducting film above T_c. It is shown that almost at all temperatures the mechanism of the temperature oscillations created by the AC current and the temperature dependence of the resistance dominates over t…
Millisecond crystal relaxation has been used to explain anomalous decay in doped alkali halides. We attribute this slowness to Fermi-Pasta-Ulam solitons. Our model exhibits confinement of mechanical energy released by excitation. Extending the model to long times is justified by its relation to solitons, excitations p…
Barkhausen noise, including both periodic and aperiodic components, is found in and near the relaxor regime of a familiar relaxor ferroelectric, PbMg$_{1/3}$Nb$_{2/3}$O$_3$, driven by a periodic electric field. The temperature dependences of both the amplitude and spectral form show that the size of the coherent dipol…
This review paper illustrates the main normal and superconducting state properties of magnesium diboride, a material known since early 1950's, but recently discovered to be superconductive at a remarkably high critical temperature Tc=40K for a binary compound. What makes MgB2 so special? Its high Tc, simple crystal st…
Directly fused diporphyrins display the extensive pi conjugation as evinced by highly perturbed electronic absorption spectra as well as lowered and largely split first oxidation potentials. Such diporphyrins prepared include meso-beta doubly linked diporphyrins 7, meso-meso beta-beta beta-beta triply linked diporphyr…
This report presents the polarizability matrix of a tri-isotropic sphere. A tri-isotropic material exhibits coupling between electric, magnetic, and in addition, a third kind of material response. Each of these three fields creates three different kind of polarizations. The paper derives the polarizability components…
In past years, both experimental and analytical approaches have been developed for eliminating preferred orientation effects on powder X-ray diffraction patterns. The state of the art does not allow one to face the problem without difficult sample treatments, mechanical randomization, pole-figure study or pattern fitt…
Abstract We examine the crystallization and chain conformation behavior of semicrystalline poly(ethylene oxide) (PEO) and amorphous poly(vinyl acetate) (PVAc) mixtures with wide‐angle X‐ray diffraction (WAXD), small‐angle X‐ray scattering (SAXS), and small‐angle neutron scattering (SANS) experiments. For blends with P…
Abstract We used neutron reflectivity to measure the interfacial width in the immiscible system polystyrene/poly( n ‐butyl methacrylate) (PS/P n BMA). Measurements were made on the same samples at temperatures ranging from below the glass‐transition temperature ( T g ) of PS to slightly above. We observed significant…
The light emission of transient laser-produced cavitation bubbles in water is investigated in a range of ambient pressures up to 5 bar and laser energies up to 30 mJ. At elevated pressures bubble luminescence can be increased more than two fold for bubbles created with the same laser energy, and up to almost an order…
Abstract The preparation and characterization of two types of ionic poly( p ‐phenylene terephthalamide) (PPTA) is described. A sufficient number of ionic groups were added to render modified PPTA soluble in dimethylsulfoxide (DMSO). In one type, a hydrogen atom of the amide group was replaced by an ionic propanesulfon…
A novel approach for determining interfacial kinetics by excluding the mass transfer effect accurately by numerical simulation of fluid flow and mass transfer in a chemical reactor is presented. In the presence of surfactant, the biphasic hydroformylation of 1-dodecene catalyzed by water-soluble rhodium complex in a s…
Abstract Poly(δ‐valerolactone) (PVL) crystals in the form of chain‐folded lamellae were prepared by isothermal crystallization from a 2‐methylbutane‐2‐ol solution. Wide‐angle and small‐angle X‐ray diffraction data, obtained from PVL lamellae sedimented to form oriented mats, were supplemented with morphological and st…