Coleen Pugh、Jin‐Young Bae、Jayesh R. Dharia 等 5 位作者1998-07-15Macromolecules
In contrast to their hydrocarbon analogues which exhibit only nematic mesophases, poly{5-[[[2‘,5‘-bis[(4‘‘-( n -(dimethylsiloxyl)alkoxy)benzoyl)oxy]benzyl]oxy]carbonyl]bicyclo[2.2.1]hept-2-ene}s and their low-molar-mass model compounds exhibit smectic C mesophases. Since nematic liquid crystals can be forced into laye…
Marine Toxins and Detection MethodsLiquid Crystal Research AdvancementsSynthetic Organic Chemistry Methods
Zhi Jing、Chen Ang、Zhi Yu 等 5 位作者1998-07-15Journal of Applied Physics
Temperature and frequency dependence of the real (ε′) and imaginary (ε″) parts of the dielectric permittivity of Ba(Ti1−yYy)O3 (0.028⩽y⩽0.258) ceramic samples were studied in the temperature range 12–500 K at 102, 103, and 104, and 105 Hz. The permittivity peaks are rounded and frequency dispersive when y>0.028…
Microwave Dielectric Ceramics SynthesisFerroelectric and Piezoelectric MaterialsDielectric properties of ceramics
Mike Tobyn1998-07-15International Journal of Pharmaceutics
Silicified microcrystalline cellulose (SMCC) has been compared with a standard grade of microcrystalline cellulose (MCC) using several physicochemical techniques in order to elucidate any chemical or polymorphic changes in the material that could be attributed to the silicification process. Samples of SMCC, MCC and dr…
Advanced Cellulose Research StudiesBauxite Residue and UtilizationLignin and Wood Chemistry
T. Venkatesan、M. Rajeswari、Zi-Wen Dong 等 5 位作者1998-07-15Philosophical Transactions of the Royal Society A Mathematical Physical and Engineering Sciences
Since the rejuvenation of interest in the rare earth manganites owing to their potential use as magnetoresistive sensors, there has been adequate research to arrive at some evaluation of the potential for these materials in a variety of technologies that would use the peculiar properties of these materials. The magnet…
Advanced Condensed Matter PhysicsElectronic and Structural Properties of OxidesMagnetic and transport properties of perovskites and related materials
Chi L. Pang、S. A. Haycock、Hamid Raza 等 8 位作者1998-07-15Physical review. B, Condensed matter
Scanning tunneling microscopy and first-principles atomic orbital based calculations have been used to study ${\mathrm{TiO}}_{2}(110)1\ifmmode\times\else\texttimes\fi{}2.$ A structure is proposed that resolves the controversy surrounding the surface morphology. Our model is simple, in that it consists only of atoms in…
Catalysis and Oxidation ReactionsElectronic and Structural Properties of OxidesSurface and Thin Film Phenomena
N. Emig、Hanh Nho Nguyen、Harald Krautscheid 等 6 位作者1998-07-15Organometallics
The dilithium salts of N, N ‘, N ‘‘-tris(trimethylsilyl)diethylenetriamine ( 1 ), N -methyl- N ‘, N ‘‘-bis(trimethylsilyl)diethylenetriamine ( 2 ), and N -methyl- N ‘, N ‘‘-bis(diisopropyl)diethylenetriamine ( 3 ) reacted in THF, at −40 °C, with AlCl 3 affording monomeric aluminum chloride derivatives 4 (55% yield), 5…
Organometallic Complex Synthesis and CatalysisCarbon dioxide utilization in catalysisbiodegradable polymer synthesis and properties
J.E. Evetts、M. G. Blamire、N. D. Mathur 等 7 位作者1998-07-15Philosophical Transactions of the Royal Society A Mathematical Physical and Engineering Sciences
Although theoretical understanding of doped mixed–valence manganites that exhibit colossal magnetoresistance (CMR) is still incomplete, the general observation of a systematic correlation at a given temperature between the magnetization and resistance both above and below the Curie temperature Tc can provide a phenome…
Advanced Condensed Matter PhysicsMagnetic and transport properties of perovskites and related materialsElectronic and Structural Properties of Oxides
Stella Sioula、Nikos Hadjichristidis、Edwin L. Thomas1998-07-15Macromolecules
The morphology of a family of four 3-miktoarm star terpolymers of polystyrene (PS), polyisoprene (PI), and polymethyl methacrylate (PMMA) was studied. For three of the samples, the molecular weight of the PMMA block was systematically varied while that of the PS and PI blocks were held fixed. In the fourth sample, the…
Polymer Surface Interaction StudiesAdvanced Polymer Synthesis and CharacterizationBlock Copolymer Self-Assembly
Wolfgang Quapp、Michael Hirsch、Olaf Imig 等 4 位作者1998-07-15Journal of Computational Chemistry
The old coordinate driving procedure to find transition structures in chemical systems is revisited. The well-known gradient criterion, ∇E(x)=0, which defines the stationary points of the potential energy surface (PES), is reduced by one equation corresponding to one search direction. In this manner, abstract curves c…
Machine Learning in Materials ScienceOrganic Chemistry Cycloaddition ReactionsVarious Chemistry Research Topics
Gerardo F. Goya、H. Rechenberg、J.Z. Jiang1998-07-15Journal of Applied Physics
The structural and magnetic evolution in copper ferrite (CuFe2O4) caused by high-energy ball milling are investigated by x-ray diffraction, Mössbauer spectroscopy, and magnetization measurements. Initially, the milling process reduces the average grain size of CuFe2O4 to about 6 nm and induces cation redistribution be…
Iron oxide chemistry and applicationsMagnetic Properties and Synthesis of FerritesMagnetic properties of thin films
A. Schwartz、Martin Dressel、G. Grüner 等 6 位作者1998-07-15Physical review. B, Condensed matter
We have measured the electrodynamic response in the metallic state of three highly anisotropic conductors, $(\mathrm{TMTSF}{)}_{2}X,$ where $X={\mathrm{PF}}_{6}$, ${\mathrm{AsF}}_{6},$ or ${\mathrm{ClO}}_{4},$ and TMTSF is the organic molecule tetramethyltetraselenofulvalene. In all three cases we find dramatic deviat…
Magnetism in coordination complexesOrganic and Molecular Conductors ResearchQuantum and electron transport phenomena
N. Moll、M. Scheffler、E. Pehlke1998-07-15arXiv
The equilibrium shapes of InAs quantum dots (i.e., dislocation-free, strained islands with sizes >= 10,000 atoms) grown on a GaAs (001) substrate are studied using a hybrid approach which combines density functional theory (DFT) calculations of microscopic parameters, surface energies, and surface stresses with elasti…
Materials Science
K. Budde、I. F. Lyuksyutov、H. Pfnuer 等 5 位作者1998-07-15arXiv
The first order phase transitions between a two-dimensional (2d) gas and the 2d solid of the first monolayer have been studied for the noble gases Ar, Kr and Xe on a NaCl(100) surface in quasi-equilibrium with the three-dimensional gas phase. Using linear temperature ramps, we show that the widths of the hysteresis lo…
Materials Science
K. Reuter、J. Schardt、J. Bernhardt 等 6 位作者1998-07-15arXiv
For the example of the SiC(111)-(3x3) reconstruction we show that a holographic interpretation of discrete Low Energy Electron Diffraction (LEED) spot intensities arising from ordered, large unit cell superstructures can give direct access to the local geometry of a cluster around an elevated atom, provided there is o…
Materials Science
Y. Tokura、Y. Okimoto、Satoshi Yamaguchi 等 6 位作者1998-07-15Physical review. B, Condensed matter
The thermally induced insulator-metal transition (IMT) has been investigated for single crystals of undoped and lightly doped ${\mathrm{LaCoO}}_{3}$ by measurements of the optical-conductivity spectra, the resistivity, and the Hall coefficient up to 800 K. The IMT around 500 K, where the spin-state transition from the…
Rare-earth and actinide compoundsAdvanced Condensed Matter PhysicsMagnetic and transport properties of perovskites and related materials
Norbert Peekhaus、Tyrrell Conway1998-07-15OpenAlex
The Entner-Doudoroff (ED) pathway was first discovered in 1952 in Pseudomonas saccharophila (21) and several years later was shown to be present in Escherichia coli (23). Although generally considered to be restricted to gram-negative bacteria, the ED pathway is present in all three phylogenetic domains, including the…
Bacterial Genetics and BiotechnologyDigestive system and related healthEnzyme Structure and Function
Frank Caruso、D. Neil Furlong、Katsuhiko Ariga 等 5 位作者1998-07-15OpenAlex
Protein-containing polyelectrolyte multilayer films of poly(styrenesulfonate) and poly(allylamine hydrochloride), fabricated by the sequential adsorption of polyelectrolyte and anti-immunoglobulin G (anti-IgG) on solid substrates, have been characterized using atomic force microscopy (AFM), scanning electron microscop…
Dendrimers and Hyperbranched PolymersMolecular Junctions and NanostructuresPolymer Surface Interaction Studies
Philippe Lalanne、Simion Aştilean、Pierre Chavel 等 5 位作者1998-07-15OpenAlex
We introduce a new structural cutoff beyond which subwavelength gratings cease to behave as homogeneous media and discuss its effects on the proper selection of the sampling periods of subwavelength diffractive elements. According to this analysis, a 3lambda-period blazed binary grating composed of square pillars is d…
Photonic and Optical DevicesOptical Coatings and GratingsPhotonic Crystals and Applications
Warren E. Pickett、Steven C. Erwin、E. C. Ethridge1998-07-15OpenAlex
We present a local orbital approach to the evaluation of the on-site repulsion energy $U$ for use in the $\mathrm{LDA}+U$ method of Anisimov and co-workers. Our objectives are to make the method more firmly based, to concentrate primarily on ground-state properties rather than spectra, and to test the method in cases…
Magnetic and transport properties of perovskites and related materialsAdvanced Condensed Matter PhysicsAdvanced Chemical Physics Studies
Carsten Ronning、H. Feldermann、R. Merk 等 6 位作者1998-07-15OpenAlex
This paper reviews x-ray photoelectron spectroscopy studies on carbon nitride (CN) and reports on results obtained from CN thin films prepared by mass selected ion-beam deposition. The core-level spectra of samples deposited at room temperature show that nitrogen is incorporated into the amorphous network in two diffe…
Metal and Thin Film MechanicsSemiconductor materials and devicesDiamond and Carbon-based Materials Research