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A Comparative Study of Sulfur Poisoning and Regeneration of Precious-Metal Catalysts

Noor Shawal Nasri、J.M. Jones、Valerie Dupont 等 4 位作者1998-09-30Energy & Fuels

This paper investigates sulfur poisoning and catalyst regeneration for alumina-supported platinum, palladium, and rhodium catalysts. Reduced catalysts and regenerated sulfur-poisoned catalysts were studied for their activity in the catalytic combustion of methane in a flow microreactor. CO adsorption, in conjunction w…

Industrial Gas Emission ControlThermal and Kinetic AnalysisCatalytic Processes in Materials Science

Ionic Strength and Curvature Effects in Flat and Highly Curved Polyelectrolyte Brushes

R. Hariharan、Claudine Biver、Jimmy W. Mays 等 4 位作者1998-09-30Macromolecules

Adsorption of poly( tert -butylstyrene)/poly(styrenesulfonate) diblocks on polystyrene latices from water is reported and interpreted with scaling theories to demonstrate the effects of ionic strength and curvature on layer thickness. The adsorbed amount increases with ionic strength from no added salt to 0.1 M, formi…

Microfluidic and Capillary Electrophoresis ApplicationsPolymer Surface Interaction StudiesElectrostatics and Colloid Interactions

Synthesis and Characterization of New Adamantane-Based Polyimides

Sheng‐Huei Hsiao、Chin-Tang Li1998-09-30Macromolecules

A new adamantane-based dietheramine, 2,2-bis[4-(4-aminophenoxy)phenyl]adamantane, was prepared in two steps from chloro displacement of p -chloronitrobenzene with the potassium phenolate of 2,2-bis(4-hydroxyphenyl)adamantane, followed by hydrazine catalytic reduction of the intermediate dinitro compound. A series of p…

Synthesis and properties of polymersSilicone and Siloxane ChemistryEpoxy Resin Curing Processes

Structure and Stability of an Amorphous Metal

Oscar Rodríguez de la Fuente、José M. Soler1998-09-30arXiv

Using molecular dynamics simulations, with a realistic many-body embedded-atom potential, and a novel method to characterize local order, we study the structure of pure nickel during the rapid quench of the liquid and in the resulting glass. In contrast with previous simulations with pair potentials, we find more crys…

Materials Sciencecond-mat.dis-nn

Inorganic Solid-State Chemistry with Main Group Element Carbodiimides

Ralf Riedel、Edwin Kroke、Axel Greiner 等 7 位作者1998-09-30Chemistry of Materials

Organosilicon carbodiimides have been successfully applied as single-source precursor compounds for the synthesis of novel ternary Si-, C-, and N-containing solid phases. Their thermally induced decomposition gives either amorphous silicon carbonitrides or polycrystalline silicon nitride and silicon carbide mixtures,…

Advanced materials and compositesAdvanced ceramic materials synthesisDiamond and Carbon-based Materials Research

Free-carrier screening of polarization fields in wurtzite GaN/InGaN laser structures

F. Della Sala、A. Di Carlo、P. Lugli 等 7 位作者1998-09-30arXiv

The free-carrier screening of macroscopic polarization fields in wurtzite GaN/InGaN quantum wells lasers is investigated via a self-consistent tight-binding approach. We show that the high carrier concentrations found experimentally in nitride laser structures effectively screen the built-in spontaneous and piezoelect…

Materials Science

Effect of Chain Flexibility on Nematic-Smectic Transition

Alexei V. Tkachenko1998-09-30arXiv

The theory of nematic-smectic phase transition in the system of uniform semi-flexible chains with hard-core repulsion is presented. Both the general density-functional formalism the tube-model calculation show that the flexibility of the chains results in a strong first-order transition, in contrast to the common weak…

cond-mat.stat-mechSoft Condensed MatterMaterials Science

Atomistic modelling of large-scale metal film growth fronts

Uwe Hansen、Peter Vogl、Vincenzo Fiorentini1998-09-30arXiv

We present simulations of metallization morphologies under ionized sputter deposition conditions, obtained by a new theoretical approach. By means of molecular dynamics simulations using a carefully designed interaction potential, we analyze the surface adsorption, reflection, and etching reactions taking place during…

Materials Science

Coulomb interaction in a quantum dot

Lin-Wang Wang1998-09-30arXiv

One approximation is made to describe a M+1 electron many-body wavefunction by a M electron many-body wavefunction and a single electron wavefunction. Under this approximation, we have derived the Coulomb energy which relates the exciton energy $E_{exc}$ in a quantum dot with the quasiparticle band gap (defined as the…

Materials Science

A First Approach to Borophosphate Structural Chemistry

Rüdiger Kniep、Holger Engelhardt、Cornelia Häuf1998-09-30Chemistry of Materials

Borophosphates (intermediate compounds of the system M x O y −B 2 O 3 −P 2 O 5 −(H 2 O)) contain complex anionic structures built of BO 4, BO 3, and PO 4 groups and their partially protonated species, respectively. A first approach to the development of a structural chemistry of borophosphates is based on linking prin…

Crystal Structures and PropertiesChemical Synthesis and CharacterizationRadioactive element chemistry and processing

The incorporation of various porphyrins into blood cells measured via flow cytometry, absorption and emission spectroscopy.

Rodica‐Mariana Ion、A. Planner、Krzysztof Wiktorowicz 等 4 位作者1998-09-30OpenAlex

The incorporation of the five following porphyrins: meso-tetra(4-phenyl)porphyrin (TPP); meso-tetra(4-sulfonato-phenyl)porphyrin (TPPS4); meso-tetra(4-naphthyl)porphyrin (TNP); tri-sulfo-tetra-phenyl porphyrin (TPPS3) and tetra-sulfonato-naphthyl porphyrin (TNPS4) into human blood cells was investigated using flow cyt…

Porphyrin and Phthalocyanine ChemistryPhotodynamic Therapy Research StudiesNanoplatforms for cancer theranostics

Product Branching Ratios of the CH + NO Reaction

Astrid Bergeat、T. Calvo、Nicolas Daugey 等 5 位作者1998-09-29The Journal of Physical Chemistry A

The multichannel CH + NO reaction was studied, at room temperature, in a low-pressure fast-flow reactor. CH was obtained from the reaction of CHBr 3 with potassium atoms. The overall rate constant was found to be (1.9 ± 0.5) × 10 -10 cm 3 molecule -1 s -1 . The relative branching ratios of NH(A 3 Π) + CO and NCO(A 2 Σ…

Advanced Chemical Physics StudiesCatalytic Processes in Materials SciencePlasma Applications and Diagnostics

Development and Manufacture of Pressure-Sensitive Products

István Benedek1998-09-29OpenAlex

Build up and classification of pressure-sensitive products physical basis of PSPs chemical basis of PSPs adhesive properties of PSPs manufacture of PSPs converting properties of PSPs end use of PSPs.

Material Properties and ApplicationsTribology and Wear AnalysisThermal and Kinetic Analysis

Modular synthesis of de novo- designed metalloproteins for light-induced electron transfer

Harald K. Rau、N. De Jonge、Wolfgang Haehnel1998-09-29Proceedings of the National Academy of Sciences

The design and chemical synthesis of two de novo four-helix bundle proteins is described; each protein has two bound cofactors. Their construction from purified peptides is based on the modular assembly of different amphiphilic helices by chemoselective coupling to a cyclic peptide template. In the hydrophobic interio…

Porphyrin and Phthalocyanine ChemistryPhotosynthetic Processes and MechanismsMolecular Junctions and Nanostructures

Extrusion method for making fiber optic preforms of special glasses

Angela B. Seddon、David Furniss、Arash Motesharei1998-09-28Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE

Extrusion of glass rods, tubes and core/clad performs of melt-derived, special glasses is being investigated to satisfy demand for preforms from which optical fiber can be drawn. These glasses include: heavy metal oxide, chalcogenide, halide as well as mixed systems such as oxyhalide, chalcohalide, and oxychalcogenide…

Material Properties and ApplicationsMaterial Science and ThermodynamicsEngineering Technology and Methodologies

Extrinsic magnetoresistance and resistance relaxation in and films and heterostructures

M. Ziese、C Srinitiwarawong、C. Shearwood1998-09-28Journal of Physics Condensed Matter

The magnetoresistance and resistance relaxation after a discontinuous field change of (LCMO) and thin film structures was investigated. We compare the magnetoresistance and resistance relaxation of epitaxial films, polycrystalline films, mechanically induced grain boundaries and heterostructures in current-perpendicul…

Multiferroics and related materialsMagnetic and transport properties of perovskites and related materialsAdvanced Condensed Matter Physics

Magnetic and transport properties of

Woo Hwan Jung1998-09-28Journal of Physics Condensed Matter

The transport and magnetic properties of A-site-deficient perovskite have been investigated. The electrical conductivity displayed a thermally activated temperature dependence between 200 and 300 K with an activation energy of 0.17 eV. The thermopower measured over a similar temperature range showed little temperature…

Thermal Expansion and Ionic ConductivityMagnetic and transport properties of perovskites and related materialsAdvanced Condensed Matter Physics

Compensation doping of Ba0.7Sr0.3TiO3 thin films

M. Copel、J. D. Baniecki、P. R. Duncombe 等 7 位作者1998-09-28Applied Physics Letters

We have investigated the effects of Mn impurities on Ba0.7Sr0.3TiO3 thin films using x-ray photoemission spectroscopy. Mn acts as an electron acceptor, compensating for the charge density found in nominally undoped films. This causes a greatly increased depletion width in acceptor-doped films. We also present evidence…

Ferroelectric and Piezoelectric MaterialsSemiconductor materials and devicesElectronic and Structural Properties of Oxides

Synchrotron x-ray microbeam diagnostics of combinatorial synthesis

E. D. Isaacs、Matthew A. Marcus、G. Aeppli 等 9 位作者1998-09-28Applied Physics Letters

X-ray microbeam techniques (spot size=3×20 μm2) have been applied to characterize the composition and structure of rare earth activated Gd(La, Sr)AlO3 phosphor thin films grown by combinatorial synthesis. Using x-ray fluorescence, x-ray diffraction and near-edge x-ray absorption spectroscopy, we have measured the chem…

Electronic and Structural Properties of OxidesMolecular Junctions and NanostructuresCatalytic Processes in Materials Science