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Existence of solutions to a phase-field model for the isothermal solidification process of a binary alloy

Jacques Rappaz、Jean-François Scheid2000-04-01Mathematical Methods in the Applied Sciences

We investigate the well-posedness of a phase-field model for the isothermal solidification of a binary alloy due to Warren–Boettinger [12]. Existence of weak solution as well as regularity and uniqueness results are established under Lipschitz and boundedness assumptions for the non-linearities. A maximum principle ho…

Metallic Glasses and Amorphous AlloysAluminum Alloy Microstructure PropertiesSolidification and crystal growth phenomena

Performance evaluation of synthesized acrylic acid grafted polypropylene within CaCO3/polypropylene composites

Fristina Rahma、S. Fellahi2000-04-01Polymer Composites

Abstract A polymeric coupling agent acrylic acid grafted polypropylene (AAgPP) was synthesized and its efficiency in CaCO 3 /PP composite was investigated. The grafting of acrylic acid monomer (AA) onto polypropylene was performed using an internal mixer. The effect of peroxyde, acrylic acid monomer content, temperatu…

Polymer crystallization and propertiesPolymer Nanocomposites and PropertiesNatural Fiber Reinforced Composites

Stress concentration near a surface step and shear localization

S. Brochard、P. Beauchamp、J. Grilhé2000-04-01Physical review. B, Condensed matter

In a previous static atomistic simulation, it has been shown unambiguously that a surface step is a privileged site for dislocation nucleation. Before dislocation nucleation, an elastic shear, localized in the plane in zone with the step where nucleation will occur, is observed. The real dislocation forms when this lo…

Microstructure and mechanical propertiesMetal and Thin Film MechanicsAluminum Alloy Microstructure Properties

Orientational phase transitions in the hexagonal phase of a diblock copolymer melt under shear flow

A. N. Morozov、A. V. Zvelindovsky、J. G. E. M. Fraaije2000-04-01Physical review. E, Statistical physics, plasmas, fluids, and related interdisciplinary topics

We generalize the earlier theory by Fredrickson [J. Rheol. 38, 1045 (1994)] to study the orientational behavior of the hexagonal phase of diblock copolymer melt subjected to steady shear flow. We use symmetry arguments to show that the orientational ordering in the hexagonal phase is a much weaker effect than in the l…

Theoretical and Computational PhysicsRheology and Fluid Dynamics StudiesBlock Copolymer Self-Assembly

Solving crystal structures inP1: an automated procedure for finding an allowed origin in the correct space group

M. C. Burla、Benedetta Carrozzini、G. Cascarano 等 5 位作者2000-04-01Journal of Applied Crystallography

Crystal structure solution in P 1 may be particularly suitable for complex crystal structures crystallizing in other space groups. However, additional efforts and human intervention are often necessary to locate correctly the structural model so obtained with respect to an allowed origin of the actual space group. An…

Enzyme Structure and FunctionCrystallization and Solubility StudiesX-ray Diffraction in Crystallography

Spontaneous deformations of the uniform director ground state induced by the surfacelike elastic terms in a thin planar nematic layer

V. M. Pergamenshchik2000-04-01Physical review. E, Statistical physics, plasmas, fluids, and related interdisciplinary topics

We study the effect of the divergence (surfacelike) K24 and K13 terms on stability of the uniform ground state of a nematic phase. It is shown that the K13 term can effectively boost the action of the K24 term. As a result, even if the two Ericksen stability conditions are satisfied, spontaneous deformations can occur…

Liquid Crystal Research AdvancementsPhotonic Crystals and ApplicationsAdvanced Materials and Mechanics

Vertical trends of oxalate concentration in two soils underAbies alba from Tuscany (Italy)

Giacomo Certini、Giuseppe Corti、F. C. Ugolini2000-04-01Journal of Plant Nutrition and Soil Science

Low-molecular-weight organic acids (LMWOA's) play an important role in soil genesis and plant physiology. Oxalic acid is one of the more common and abundant LMWOA's in forest soils, where it accumulates especially as salts of Ca. In two soils under silver fir (Abies alba Mill.) from Tuscany, Italy, we measured the oxa…

Soil Carbon and Nitrogen DynamicsSoil and Unsaturated FlowClay minerals and soil interactions

Sol-Gel-Process in the Ammono-System - a Novel Access to Silicon Based Nitrides

Josua Löffelholz、J. Engering、Martin Jansen2000-04-01Zeitschrift für anorganische und allgemeine Chemie

Controlled coammonolysis of elementalkylamides in aprotic organic solvents at low temperatures have been shown to result in the formation of polyazanes. The synthetic procedure developed may be addressed as “sol-gel-route in the ammono system”. Pyrolysis of these novel polymer precursors gave access to multinary nitri…

Advanced ceramic materials synthesisSynthesis and characterization of novel inorganic/organometallic compoundsSilicone and Siloxane Chemistry

Microbiologically influenced corrosion of AISI type 304 stainless steels under fresh water biofilms

R. P. George、P. Muraleedharan、N. Parvathavarthini 等 5 位作者2000-04-01Materials and Corrosion

The influence of biofilms formed by microorganisms on the corrosion behaviour of stainless steel (SS) in various fresh water environments was studied using electrochemical techniques. Biofilm characterization studies showed an algal-dominated biofilm in the normal dark and light exposures, whereas, in the continuous d…

Corrosion Behavior and InhibitionHydrogen embrittlement and corrosion behaviors in metalsConcrete Corrosion and Durability

Evaluation of surface degradation of silicone rubber using gas chromatography/mass spectroscopy

Hiroya Homma、T. Kuroyagi、Kunikazu Izumi 等 6 位作者2000-04-01IEEE Transactions on Power Delivery

Analysis using gas chromatography/mass spectroscopy (GC/MS) was performed for evaluation of surface degradation of silicone insulating materials. Silicones are used as coatings for porcelain insulators and shed material for high voltage composite insulators. A comparison between virgin silicone rubber and aged silicon…

High voltage insulation and dielectric phenomenaAnalytical Chemistry and SensorsSmart Materials for Construction

Deformation Heterogeneity in Cellular Al Alloys

A.-F. Bastawros、A. G. Evans2000-04-01Advanced Engineering Materials

Cell ellipticity and non-planar membranes are thought to be dominant degradation factors of cellular metals. The mechanisms operating at the cell/membrane level in both closed and open cell Al alloys have been established by following the evolution of deformation with cell-level resolution using digital image correlat…

Electron and X-Ray Spectroscopy Techniques

The Study of the Origin of the Anomalously Large Thermoelectric Power of Si/Ge Superlattice Thin Film

Hiroko Uchino、Yoichi Okamoto、Toshio Kawahara 等 4 位作者2000-04-01Japanese Journal of Applied Physics

We present the experimental framework for the origin of the anomalously large thermoelectric power for Si and Au-doped Ge superlattice thin film. The thermoelectric power of the sample still remains anomalously large even though the superlattice structure begins to collapse. An amorphous Ge thin film displays large th…

Advanced Thermoelectric Materials and DevicesSemiconductor materials and interfacesThermal Radiation and Cooling Technologies

Evidence of scattering anisotropy effects on boundary conditions of the diffusion equation

Gabriel Popescu、Claudia Mujat、Aristide Dogariu2000-04-01Physical review. E, Statistical physics, plasmas, fluids, and related interdisciplinary topics

We present experimental evidence that the diffusion process close to the boundary is fundamentally different from the bulk diffusion in the sense that it is affected by the scattering properties of the individual centers. Systematic measurements show a nontrivial behavior of the extrapolation length ratio on the scatt…

Material Dynamics and PropertiesOptical Imaging and Spectroscopy TechniquesNMR spectroscopy and applications

Synthesis, characterization and electrochemistry of bismuth porphyrins: X-ray crystal structure of (OEP)Bi(SO3CF3)

Lydie Michaudet、Dominique Fasseur、Roger Guilard 等 7 位作者2000-04-01Journal of Porphyrins and Phthalocyanines

The metalation of several free base porphyrins by the bismuth salts Bi(NO 3 ) 3 and Bi(SO 3 CF 3 ) 3 in DMF or pyridine is described. The resulting stable Bi(III) porphyrin complexes are characterized by electrochemistry, 1 H NMR and UV-vis spectroscopy. The structure of ( OEP ) Bi ( SO 3 CF 3 ) was also determined by…

Metal-Organic Frameworks: Synthesis and ApplicationsPorphyrin and Phthalocyanine ChemistryInorganic Fluorides and Related Compounds

Superplastic Behavior of Fine‐Grained β‐Silicon Nitride Material under Compression

Guodong Zhan、Mamoru Mitomo、Toshiyuki Nishimura 等 6 位作者2000-04-01Journal of the American Ceramic Society

The deformation behavior of a hot‐pressed, fine‐grained β‐Si 3 N 4 ceramic was investigated in the temperature range 1450°—1650°C, under compression, and the results for strain rate and temperature dependence of the flow stress are presented here. The present results show that the material is capable of high rates of…

Advanced ceramic materials synthesisMetal and Thin Film MechanicsAdvanced materials and composites

The influence of the solubility of zinc phosphate pigments on their anticorrosive behaviour

Guillermo Blustein、B. del Amo、R. Romagnoli2000-04-01Pigment & Resin Technology

The objective of this work was to study the anticorrosive behaviour of three commercial pigments containing micronized zinc phosphate. The chemical analyses of the pigments were carried out in the laboratory to characterise them with respect to their composition and soluble matter. It was proposed to check pigments’ e…

Corrosion Behavior and InhibitionBuilding materials and conservationConcrete Corrosion and Durability

Anomalous spin susceptibility and magnetic polaron formation in the double-exchange systems

Hongsuk Yi、Nam Hwi Hur、Jaejun Yu2000-04-01Physical review. B, Condensed matter

The magnetic susceptibility and spin-spin correlation of the double-exchange model for doped manganites are investigated through the Monte Carlo calculations on the three-dimensional lattice model. Deviations of the susceptibility from the Curie-Weiss behavior above the ferromagnetic ordering temperature ${T}_{c}$ see…

Magnetic and transport properties of perovskites and related materialsRare-earth and actinide compoundsAdvanced Condensed Matter Physics

THE SORPTION OF ORGANIC MATTER IN SOILS AS AFFECTED BY THE NATURE OF SOIL CARBON

Klaus Kaiser、Ludwig Haumaier、Wolfgang Zech2000-04-01Soil Science

Recent studies have shown that soil organic carbon (OC) may either hinder or favor the sorption of dissolved organic matter (DOM) in soils. Our concept was that the nature of soil OC determines these contrasting findings. To test this hypothesis, we compared the DOM sorption in soils with OC derived from biomass decom…

Heavy metals in environmentSoil and Water Nutrient DynamicsClay minerals and soil interactions

Route to Higher Fidelity FT-IR Imaging

Rohit Bhargava、Shi-Qing Wang、Jack L. Koenig2000-04-01Applied Spectroscopy

FT-IR imaging employing a focal plane array (FPA) detector is often plagued by low signal-to-noise ratio (SNR) data. A mathematical transform that re-orders spectral data points into decreasing order of SNR is employed to reduce noise by retransforming the ordered data set using only a few relevant data points. This a…

Liquid Crystal Research AdvancementsPhase-change materials and chalcogenidesOptical Polarization and Ellipsometry

Improvement of Memory Retention Characteristics in Ferroelectric Neuron Circuits Using a Pt/SrBi 2Ta 2O 9/Pt/Ti/SiO 2/Si Structure-Field Effect Transistor as a Synapse Device

Sung-Min Yoon Sung-Min Yoon、Eisuke Tokumitsu、Hiroshi Ishiwara2000-04-01Japanese Journal of Applied Physics

A metal-ferroelectric-metal-oxide-semiconductor field effect transistor (MFMOS-FET) with a Pt/SrBi 2 Ta 2 O 9 /Pt/Ti/SiO 2 /Si structure was fabricated on a silicon-on-insulator (SOI) structure in order to improve the memory retention characteristics of ferroelectric neuron circuit. The area ratio of MOS capacitor to…

Ferroelectric and Piezoelectric MaterialsAdvanced Memory and Neural ComputingAcoustic Wave Resonator Technologies