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Field emission theory beyond WKB - the full image problem

T. C. Choy、A. H. Harker、A. M. Stoneham2003-05-13arXiv

The classic theory of electron field emission from a cold metal surface due to Fowler and Nordheim (FN) is re-examined and found to violate the validity criteria for the WKB approximation, for electric fields greater than about 1V per micron. In this study we shall examine the complete solution without invoking the WK…

Materials ScienceMesoscale and Nanoscale PhysicsSoft Condensed Matter

Nanoscale Structure of Poly(Ethylene Glycol) Hybrid Block Copolymers containing Amphiphilic β-Strand Peptide Sequences

A. Rösler、Harm‐Anton Klok、Ian W. Hamley 等 5 位作者2003-05-13Biomacromolecules

This paper discusses the solid state and melt nanoscale structure of a series of novel poly(ethylene glycol) (PEG) hybrid di- and triblock copolymers, which contain amphiphilic beta-strand peptide sequences. The block copolymers have been prepared via solid-phase synthesis, affording perfectly monodisperse peptide seg…

Supramolecular Self-Assembly in MaterialsChemical Synthesis and AnalysisRNA Interference and Gene Delivery

Small Ti clusters for catalysis of hydrogen exchange in NaAlH4

Maximilian Fichtner、Olaf Fuhr、Oliver Kircher 等 4 位作者2003-05-13Nanotechnology

Colloidal Ti has been synthesized following a method described in the literature. Extended x-ray absorption fine structure measurements indicate the presence of small colloidal entities, consisting of only a few core Ti atoms which are coordinated by O atoms from tetrahydrofuran (THF). The results can be explained by…

Advanced Chemical Physics StudiesAmmonia Synthesis and Nitrogen ReductionHydrogen Storage and Materials

Weakly nonlocal continuum physics - the Ginzburg-Landau equation

Peter Van2003-05-13arXiv

Some peculiarities of the exploitation of the entropy inequality in case of weakly nonlocal continuum theories are investigated and refined. As an example it is shown that the proper application of the Liu procedure leads to the Ginzburg-Landau equation in case of a weakly nonlocal extension of the constitutive space…

Materials Science

Field-doping of C60 crystals: A view form theory

Erik Koch、Olle Gunnarsson、Samuel Wehrli 等 4 位作者2003-05-13arXiv

The proposal of using the field-effect for doping organic crystals has raised enormous interest. To assess the feasibility of such an approach, we investigate the effect of a strong electric field on the electronic structure of C60 crystals. Calculating the polarization of the molecules and the splittings of the molec…

SuperconductivityMaterials Science

Sonochemical Modification of the Superconducting Properties of MgB2

Tanya Prozorov、Ruslan Prozorov、Alexey Snezhko 等 4 位作者2003-05-13arXiv

Ultrasonic irradiation of magnesium diboride slurries in decalin produces material with significant inter-grain fusion. Sonication in the presence of Fe(CO)5 produces magnetic Fe2O3 nanoparticles embedded in the MgB2 bulk. The resulting superconductor-ferromagnet composite exhibits considerable enhancement of the magn…

Materials ScienceSuperconductivity

Thermal Remagnetization in Polycrystalline Permanent Magnets

R. Schumann、L. Jahn2003-05-13arXiv

The thermal remagnetization (TR), i.e. the reentrance of magnetization upon heating in a steady-field demagnetized sample, is a common feature to the four types of polycrystalline permanent magnets, mainly utilized for practical purposes, i.e. barium ferrites, SmCo5, Sm2Co17 and NdFeB magnets. The effect is small for…

Materials Science

Nature of Charge Carriers in Disordered Organic Molecular Semiconductors

Ajit Kumar Mahapatro、Subhasis Ghosh2003-05-13arXiv

Understanding the charge carrier transport in the disordered organic molecular semiconductors is a fascinating and still unresolved problem in modern condensed-matter physics, yet has an extremely important bearing on their application in ``plastic'' based field effect transistor, light emitting diodes and lasers. The…

Materials Science

Versatile Double-Templating Synthesis Route to Silica Monoliths Exhibiting a Multimodal Hierarchical Porosity

Jan‐Henrik Smått、Stephan A. Schunk、Mika Lindén2003-05-13Chemistry of Materials

Monolithic silica exhibiting a trimodal, hierarchical pore structure has successfully been prepared via sol−gel-processing. Monolithic bodies with interconnected macropores in the micrometer range are a result of controlled phase separation and gelation kinetics, whereas textural mesopores in the 10−20 nm range origin…

Mesoporous Materials and CatalysisAerogels and thermal insulationPolyoxometalates: Synthesis and Applications

Enhancing the vascularization of three‐dimensional porous alginate scaffolds by incorporating controlled release basic fibroblast growth factor microspheres

Anat Perets、Yaacov Baruch、Felix Weisbuch 等 6 位作者2003-05-13OpenAlex

Site-specific delivery of angiogenic growth factors from tissue-engineered devices should provide an efficient means of stimulating localized vessel recruitment to the cell transplants and would ensure cell survival and function. In the present article, we describe the construction of a novel porous alginate scaffold…

Electrospun Nanofibers in Biomedical ApplicationsTissue Engineering and Regenerative MedicineBone Tissue Engineering Materials

The role of magnesium in stabilising amorphous calcium carbonate and controlling calcite morphologies

Eva Loste、Rory M. Wilson、Ram Seshadri 等 4 位作者2003-05-13OpenAlex

Calcium carbonate has been precipitated from aqueous solutions containing magnesium under conditions of high supersaturation. The precipitates were analysed over time using X-ray diffraction (XRD) and Infrared Spectroscopy (IR), and it was demonstrated that in all cases amorphous calcium carbonate (ACC) was the first…

Calcium Carbonate Crystallization and InhibitionBone Tissue Engineering MaterialsPaleontology and Stratigraphy of Fossils

Synthesis and solution properties of alternating maleimide/styrene hyperbranched copolymers via controlled radical mechanism

Koji Ishizu、Chisato Takashimizu、Takeshi Shibuya 等 4 位作者2003-05-12Polymer International

Abstract Copolymerizations of ( N , N ‐diethyldithiocarbamyl)methylstyrene (inimer: DTCS) with maleimide (MI) were carried out under UV irradiation. DTCS monomers play an important role in this copolymerization system as an inimer that is capable of initiating radical polymerization of the vinyl group. Reactivity rati…

Dendrimers and Hyperbranched PolymersSynthetic Organic Chemistry MethodsAdvanced Polymer Synthesis and Characterization

Pressure effects onNaMnF4: Structural correlations and Jahn-Teller effect from crystal-field spectroscopy

Fernando Aguado、Fernando Rodríguez、P. Núñez2003-05-12Physical review. B, Condensed matter

This work investigates the optical absorption spectrum of the ${\mathrm{NaMnF}}_{4}$-layered perovskite and its variation with pressure. The spectrum basically consists of three broadbands located at 1.916, 2.263, and 2.817 eV, which correspond to the crystal-field (CF) transitions ${}^{5}{\stackrel{\ensuremath{\right…

Inorganic Fluorides and Related CompoundsMultiferroics and related materialsSolid-state spectroscopy and crystallography

The influence of wax content on the physical properties of low‐density polyethylene–wax blends

Vladimir Djoković、T.N. Mtshali、A. S. Luyt2003-05-12Polymer International

Abstract The influence of wax content on the thermal, mechanical and viscoelastic properties of low‐density polyethylene (LDPE)–oxidized wax miscible blends have been investigated. It was found that small concentrations of wax improved physical properties such as thermal stability, elastic modulus and yield stress. At…

Polymer Nanocomposites and PropertiesPolymer crystallization and propertiesNatural Fiber Reinforced Composites

Correlation between configurational entropy and structural relaxation time in glass-forming liquids

D. Prevosto、M. Lucchesi、S. Capaccioli 等 5 位作者2003-05-12Physical review. B, Condensed matter

Recent studies relate the slowing down of the structural relaxation time of supercooled liquids to a decrease of the excess entropy ${S}_{\mathrm{exc}}$ of the melt with respect to the crystal. The theoretical basis of such a result was often found in the Adam Gibbs (AG) theory, implicitly assuming a proportionality b…

Material Dynamics and PropertiesPhase Equilibria and ThermodynamicsChemical Thermodynamics and Molecular Structure

The chain extension of anionic prepolymers in the preparation of aqueous poly(urethane–urea) dispersions

Mika Lahtinen、Rachel K Pinfield、Colin Price2003-05-12Polymer International

Abstract Anionic polyurethane prepolymers end‐capped with isocyanate groups were dispersed and chain‐extended in aqueous media using three different extension agents: hydrazine, 1,2‐ethylene diamine (EDA) and 1,2‐propylene diamine (PDA). Two types of prepolymer were used. The first was prepared from isophorone diisocy…

Corrosion Behavior and InhibitionPolymer Nanocomposites and PropertiesPolymer composites and self-healing

Partial Discharge Detection and Localization in High Voltage Transformers Using an Optical Acoustic Sensor

Alison Kay Lazarevich2003-05-12OpenAlex

A partial discharge (PD) is the dissipation of energy caused by the buildup of localized electric field intensity. In high voltage devices such as transformers, this buildup of charge and its release can be symptomatic of problems associated with aging, such as floating components and insulation breakdown. This is why…

High voltage insulation and dielectric phenomenaAdvanced Fiber Optic SensorsPower Transformer Diagnostics and Insulation

The influence of interphase on nylon‐6/nano‐SiO2 composite materials obtained from in situ polymerization

Ying Li、Jian Yu、Zhao‐Xia Guo2003-05-12Polymer International

Abstract Three commercially available silane, titanate and aluminate based coupling agents were used to pretreat nano‐SiO 2 for the preparation of nylon‐6/nano–SiO 2 composites via in situ polymerization. The interphases formed in different composite systems and their influence on material properties were investigated…

biodegradable polymer synthesis and propertiesPolymer Nanocomposites and PropertiesPolymer crystallization and properties

Strontium‐based initiator system for ring‐opening polymerization of cyclic esters

Zhaohui Tang、Xuesi Chen、Qizhi Liang 等 7 位作者2003-05-12Journal of Polymer Science Part A Polymer Chemistry

Abstract An amino isopropoxyl strontium (Sr‐PO) initiator, which was prepared by the reaction of propylene oxide with liquid strontium ammoniate solution, was used to carry out the ring‐opening polymerization (ROP) of cyclic esters to obtain aliphatic polyesters, such as poly(ε‐caprolactone) (PCL) and poly( L ‐lactide…

biodegradable polymer synthesis and propertiesAdvanced Polymer Synthesis and CharacterizationCarbon dioxide utilization in catalysis