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第 202399 / 206404 页 · 当前展示 4,047,961–4,047,980 / 4,128,070 条匹配结果 · 摘要仅作预览

Nuclear-spin relaxation in paramagnetic complexes in the slow-motion regime for the electron spin: The anisotropic pseudorotation model for S=1 and the interpretation of nuclear magnetic relaxation dispersion results for a low-symmetry Ni(II) complex

Tomas Larsson、Per-Olof Westlund、Józef Kowalewski 等 4 位作者1994-07-15The Journal of Chemical Physics

This work presents the anisotropic pseudorotation (APR) model, which is a new dynamic model for the interpretation of experimental nuclear spin-lattice relaxation times in paramagnetic (S=1) complexes of low symmetry. It comprises two dynamic processes active in modulating the zero-field splitting interaction (ZFS). R…

Magnetism in coordination complexesAdvanced NMR Techniques and ApplicationsElectron Spin Resonance Studies

Plasma modification of polymethylmethacrylate and polyethyleneterephthalate surfaces

P. Gröning、M. Collaud、Giovanni Dietler 等 4 位作者1994-07-15Journal of Applied Physics

Noble gas (He,Ar,Xe) and reactive gas (O2,N2) plasma treatments of polymethylmethacrylate (PMMA) and polyethyleneterephthalate (PET) surfaces were performed in an electron-cyclotron-resonance plasma. In situ surface analysis by x-ray photoelectron spectroscopy reveals well-defined surface compositions. From these meas…

Surface Modification and SuperhydrophobicityMass Spectrometry Techniques and ApplicationsIon-surface interactions and analysis

Phase morphology in block copolymer systems

Edwin L. Thomas、Robert L. Lescanec1994-07-15Philosophical Transactions of the Royal Society of London Series A Physical and Engineering Sciences

Abstract Microphase separation in block copolymer systems forms well-defined, periodic structure on the sub-micron length scale. This structure arises from the system striving to satisfy the delicate balance of minimizing the area of contact between incompatible chain segments and maximizing the conformational entropy…

Surfactants and Colloidal SystemsRheology and Fluid Dynamics StudiesBlock Copolymer Self-Assembly

Onset of electrical conduction in Pt and Ni films

A. I. Maaroof、Brian L. Evans1994-07-15Journal of Applied Physics

The resistance Rf of Pt and Ni films has been measured during deposition (by ion-beam sputtering) for different deposition rates r and substrate temperatures TS (300≤TS≤575 K). At the onset of deposition (the nucleation stage) Rf varies only slowly with deposition time T and oscillations occur in Rf vs T which are dam…

Semiconductor materials and devicesCopper Interconnects and ReliabilitySurface and Thin Film Phenomena

Lamellae and their organization in melt-crystallized polymers

D. C. Bassett1994-07-15Philosophical Transactions of the Royal Society of London Series A Physical and Engineering Sciences

Abstract Significant advances in knowledge of lamellae and their organization in meltcrystallized polymers have stemmed from the ability to examine internal morphologies systematically with the transmission electron microscope. Spherulites form because the first-forming (dominant) lamellae branch repetitively, often a…

Polymer crystallization and propertiesPolymer Nanocomposites and Propertiesbiodegradable polymer synthesis and properties

π bonding versus electronic-defect generation: An examination of band-gap properties in amorphous carbon

U. Stephan、Thomas Frauenheim、P. Blaudeck 等 4 位作者1994-07-15Physical review. B, Condensed matter

The electronic properties of amorphous carbon structures with varying microscopic mass densities, ranging from 2.0 to 3.52 g/${\mathrm{cm}}^{3}$, are analyzed. Using a semiempirical density-functional approach the model structures were generated by molecular dynamics performing a simulated cooling of liquid carbon clu…

Carbon Nanotubes in CompositesHigh-pressure geophysics and materialsDiamond and Carbon-based Materials Research

Stability of vacancy defects in MgO: The role of charge neutrality

Andrew J. Gibson、Roger Haydock、John P. LaFemina1994-07-15Physical review. B, Condensed matter

The energetics and electronic structure of a series of neutral and charged oxygen and magnesium vacancy defects (F, ${\mathit{F}}^{+}$, ${\mathit{F}}^{2+}$, V, ${\mathit{V}}^{\mathrm{\ensuremath{-}}}$, ${\mathit{V}}^{2\mathrm{\ensuremath{-}}}$, and P centers) in MgO have been computed using the stationary total-energy…

Magnesium Alloys: Properties and ApplicationsBoron and Carbon Nanomaterials ResearchMagnesium Oxide Properties and Applications

Folding kinetics of proteinlike heteropolymers

Nicholas D. Socci、José Nelson Onuchic1994-07-15The Journal of Chemical Physics

Using a simple three-dimensional lattice copolymer model and Monte Carlo dynamics, we study the collapse and folding of proteinlike heteropolymers. The polymers are 27 monomers long and consist of two monomer types. Although these chains are too long for exhaustive enumeration of all conformations, it is possible to e…

Material Dynamics and PropertiesBlock Copolymer Self-AssemblyAdvanced Physical and Chemical Molecular Interactions

Surface modification of polyethylene fiber by graft polymerization

Masaru Mori、Yoshikimi Uyama、Yoshito Ikada1994-07-15Journal of Polymer Science Part A Polymer Chemistry

Abstract To improve the wettability and adhesion, graft polymerization of acrylamide (AAm) and glycidyl methacrylate (GMA) was performed onto the surface of ultra‐high modulus polyethylene (UHMPE) fiber pretreated with Ar plasma. Following the plasma treatment and the subsequent exposure to air to introduce peroxides…

Surface Modification and SuperhydrophobicityAdvanced Sensor and Energy Harvesting MaterialsElectrospun Nanofibers in Biomedical Applications

Three-terminal adaptive nematic liquid-crystal lens device

Nabeel A. Riza、Michael DeJule1994-07-15Optics Letters

A 1 mm x 1 mm nematic liquid-crystal three-terminal device for optical beam forming (focusing/spoiling) is fabricated. A thin-film-resistor network on the device substrate layer is used to control the voltages on the 98 internal lens electrodes by use of only one variable external driver. By using a high-resistance th…

Photonic and Optical DevicesLiquid Crystal Research AdvancementsPhase-change materials and chalcogenides

Germanium quantum dots: Optical properties and synthesis

James R. Heath、J. J. Shiang、A. Paul Alivisatos1994-07-15The Journal of Chemical Physics

Three different size distributions of Ge quantum dots (≳200, 110, and 60 Å) have been synthesized via the ultrasonic mediated reduction of mixtures of chlorogermanes and organochlorogermanes (or organochlorosilanes) by a colloidal sodium/potassium alloy in heptane, followed by annealing in a sealed pressure vessel at…

Quantum Dots Synthesis And PropertiesSilicon Nanostructures and PhotoluminescenceSemiconductor materials and interfaces

Water chemistry on surface defect sites: Chemidissociation versus physisorption on MgO(001)

C. A. Scamehorn、N. M. Harrison、Maureen I. McCarthy1994-07-15The Journal of Chemical Physics

The following paper presents the results of a theoretical study that probed the chemistry of water at structural defects on the MgO (001) surface. The computational technique used was periodic Hartree–Fock (PHF) theory with density functional based correlation corrections. The adsorption energies for water adsorbed on…

Ammonia Synthesis and Nitrogen ReductionElectronic and Structural Properties of OxidesMagnesium Oxide Properties and Applications

Fluorescence-line narrowing in CdSe quantum dots: Surface localization of the photogenerated exciton

M. Nirmal、C. B. Murray、Moungi G. Bawendi1994-07-15Physical review. B, Condensed matter

The electronic properties of shallow band-edge surface traps in nanometer-size CdSe quantum dots are probed using fluorescence-line-narrowing spectroscopy. We find large changes in electron-hole-pair radiative lifetimes and couplings to LO phonons as the temperature is changed from 1.75 to 10 K. We attribute these cha…

Semiconductor Quantum Structures and DevicesQuantum Dots Synthesis And PropertiesChalcogenide Semiconductor Thin Films

Elastic constants of boron nitride

M. Grimsditch、E. S. Zouboulis、A. Polian1994-07-15OpenAlex

Using Brillouin scattering the three independent elastic stiffness constants cij of single-crystal cubic boron nitride have been measured: c11=820, c12=190, and c44=480 GPa. The resulting bulk modulus, 400 GPa, is in reasonable agreement with two independent determinations obtained from x-ray measurements in a diamond…

Diamond and Carbon-based Materials ResearchForce Microscopy Techniques and ApplicationsBoron and Carbon Nanomaterials Research

Resonant 3d, 3pand 3sPhotoemission in Transition Metal Oxides Predicted at 2pThreshold

A. Tanaka、Taeho Jo1994-07-15OpenAlex

We present calculated 3 d , 3 p and 3 s resonant photoemission (RPE) spectra in the transition metal (TM) compounds CuO, NiO, CoO, FeO, MnO and TiO 2 at TM 2 p core threshold on the basis of a cluster model. Our model includes the intraatomic multipole electron-electron interactions and the hybridization between trans…

ZnO doping and propertiesCopper-based nanomaterials and applicationsElectron and X-Ray Spectroscopy Techniques

Control of reflectivity and bistability in displays using cholesteric liquid crystals

Deng‐Ke Yang、John L. West、L.-C. Chien 等 4 位作者1994-07-15OpenAlex

It is demonstrated that the reflective properties and bistability of cholesteric liquid crystals can be controlled by proper surface treatment and dispersed polymers. Dispersing a polymer in the liquid crystal or using a cell with an inhomogeneous surface anchoring creates permanent defects which result in long-term b…

Liquid Crystal Research AdvancementsPhotonic Crystals and ApplicationsElectrowetting and Microfluidic Technologies

Sorbsan

Clare Williams1994-07-14British Journal of Nursing

Seaweed has been used since the 1800s in the treatment of wounds. Sorbsan is an alginate dressing designed to absorb large amounts of exudate. Sorbsan is removed by irrigation without causing damage to newly forming tissue. Sorbsan is a relatively painless dressing to remove.

Seaweed-derived Bioactive CompoundsCollagen: Extraction and CharacterizationFood Industry and Aquatic Biology

Scattering of non-relativistic electrons in tip structures

M. Weber1994-07-14Journal of Physics D Applied Physics

Fine tip structures are required for many applications in different technologies, for example in scanning probe microscopy or vacuum microelectronic devices. Tips can be produced with nanometre precision by the electron-beam-induced deposition technique. The deposition process, however, is still not really understood.…

Advancements in Photolithography TechniquesElectron and X-Ray Spectroscopy TechniquesIntegrated Circuits and Semiconductor Failure Analysis

Turcasarin, das bisher am stärksten expandierte Porphyrin

Jonathan L. Sessler、Steven J. Weghorn、Vincent M. Lynch 等 4 位作者1994-07-14Angewandte Chemie

40π‐Elektronen und zehn Pyrrol‐Einheiten enthält der Makrocyclus 1 , das bisher größte expandierte Porphyrin. Das Tetrahydrochlorid von 1 wurde in Lösung und im Festkörper charakterisiert; nach diesen Untersuchungen liegt der Makrocyclus als Enantiomerenpaar vor, was auf einer Verdrillung des Ringsystems beruht. magni…

Molecular Sensors and Ion DetectionPorphyrin and Phthalocyanine ChemistryLanthanide and Transition Metal Complexes

Physical properties of spray pyrolysed pure and doped ZnO thin films

P Pushparajah、A.K. Arof、S. Radhakrishna1994-07-14Journal of Physics D Applied Physics

ZnO and ZnO:Li films (1-3 mu m thickness) were deposited on a soda lime glass substrate by a spray pyrolysis technique using ZnCl 2 and LiCl as starting materials. Physical properties of these films were studied as a function of substrate temperature T s and lithium concentration. The best ZnO film was obtained for T…

ZnO doping and propertiesGas Sensing Nanomaterials and SensorsCopper-based nanomaterials and applications