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On the origin of itinerant electron behaviour and long-range ferromagnetic order in La1-xSrxCoO3

P. Ganguly、P. S. Anil Kumar、P. N. Santhosh 等 4 位作者1994-01-10Journal of Physics Condensed Matter

The itinerant electron ferromagnetism in La 1-x Sr x CoO 3 (0.1<or=x<or=0.5) has been reinvestigated. AC magnetic susceptibility studies on these systems have been carried out for the first time. The nature of the susceptibility indicates the freezing of superparamagnetic clusters at low values of x (<0.3) and long-ra…

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

Copper precipitation in FeCu, FeCuMn, and FeCuNi dilute alloys followed by X-ray absorption spectroscopy

F. Maury、N. Lorenzelli、M.H. Mathon 等 5 位作者1994-01-10Journal of Physics Condensed Matter

Samples of FeCu, FeCuMn, FeCuNi, and FeCuCr alloys containing 1.5 wt% of each solute have been electron irradiated around 290 degrees C or thermally aged at 500 degrees C for various times. It is known that such treatments induce Cu precipitation; the Cu depletion of the matrix is measured by the resistivity decrease…

Microstructure and Mechanical Properties of SteelsFusion materials and technologiesRare-earth and actinide compounds

Phonon transport in strong-scattering media

Ping Sheng、Minyao Zhou、Zhao-Qing Zhang1994-01-10Physical Review Letters

We study phonon transport in random 3D lattices when the mean free path l becomes comparable to the lattice spacing a. Through numerical simulation, it is shown that in contrast to the electronic case, here the Ioffe-Regel criterion is inaccurate in the prediction of phonon localization. By using the Thouless criterio…

Quantum and electron transport phenomenaThermal properties of materialsRandom lasers and scattering media

(Dy0.5Er0.5)Al2: A large magnetocaloric effect material for low-temperature magnetic refrigeration

K. A. Gschneidner、Hiroyuki Takeya、J. O. Moorman 等 4 位作者1994-01-10Applied Physics Letters

The low-temprature heat capacity and ac and dc magnetic properties of (Dy0.5Er0.5)Al2 have been studied as a function of magnetic fields up to ∼10 T. The magnetocaloric effect in (Dy0.5Er0.5)Al2 is 30% larger than that of the prototype material, GdPd. Magnetic measurements show that there is no measurable magnetic hys…

Physics of Superconductivity and MagnetismMagnetic and transport properties of perovskites and related materialsThermal Expansion and Ionic Conductivity

Effect of viscosity ratio and processing conditions on the morphology of blends of liquid crystalline polymer and polypropylene

M. Heino、P. Hietaoja、Tommi Vainio 等 4 位作者1994-01-10Journal of Applied Polymer Science

Abstract The effect of viscosity ratio and processing conditions on LCP/PP blend morphology was studied. The viscosity ratio (η LCP /η PP ) was varied from 0.1 to 3.6 by using five different polypropylene grades as the matrix and two LCPs as the dispersed phase (20 wt %). The most spontaneous fiber formation was achie…

Polymer crystallization and propertiesPolymer Nanocomposites and PropertiesRheology and Fluid Dynamics Studies

13C,14N and15N ENDOR measurements on the single substitutional nitrogen centre (P1) in diamond

A. Peter Cox、Mark E. Newton、J M Baker1994-01-10Journal of Physics Condensed Matter

New ENDOR measurements on the single substitutional nitrogen centre in diamond are reported. The CW-ENDOR mechanism utilizes cross relaxation, and measurements have been made on both 14 N and 15 N, as well as the first detailed 13 C ENDOR study on the isotope at the natural abundance of 1.1%. The change in EPR intensi…

Diamond and Carbon-based Materials ResearchRadioactive element chemistry and processingAtomic and Subatomic Physics Research

Plasma modification of cellulose fibers: Effects on some polymer composite properties

Johan M. Felix、Paul Gatenholm、H. P. Schreiber1994-01-10Journal of Applied Polymer Science

Abstract Cellulose fibers have been surface‐modified by selected cold, microwave plasma treatments. Inverse gas chromatographic (IGC), XPS, and SEM analyses showed surface treatment to be incomplete, but, nevertheless, effective in controllably altering the acid/base interaction balance of fiber surfaces. Surface‐modi…

Polymer Nanocomposites and PropertiesHigh voltage insulation and dielectric phenomenaAdsorption, diffusion, and thermodynamic properties of materials

Fast and slow visible luminescence bands of oxidized porous Si

D. Kovalev、I. D. Yaroshetzkii、T. Muschik 等 5 位作者1994-01-10Applied Physics Letters

The visible luminescence of porous Si is known to contain at least two spectrally distinct emission bands with widely different response times. The orange-red luminescence component (1.5–1.9 eV) decays in times being of the order of 10 μs at room temperature. The blue-green band (2.3–2.6 eV) is very much faster with r…

Luminescence Properties of Advanced MaterialsSemiconductor materials and devicesSilicon Nanostructures and Photoluminescence

Blue-green luminescence from porous silicon carbide

Takahiro Matsumoto、Jun Takahashi、Teruyuki Tamaki 等 6 位作者1994-01-10Applied Physics Letters

Porous silicon carbide has been fabricated using single crystal 6H-SiC that has a wider indirect band gap than silicon crystal. Intense blue-green luminescence has been observed at room temperature. The peak wavelength is around 460 nm, below the band gap of crystalline SiC. The luminescence intensity is about 100 tim…

Semiconductor materials and devicesThin-Film Transistor TechnologiesSilicon Nanostructures and Photoluminescence

Bulk superconductivity at an elevated temperature (Tc≊12 K) in a nickel containing alloy system Y-Ni-B-C

R. Nagarajan、Chandan Mazumdar、Z. Hossain 等 9 位作者1994-01-10Physical Review Letters

We report here our discovery of bulk superconductivity at rather high ${\mathit{T}}_{\mathit{c}}$ in samples having nominal compositions ${\mathrm{YNi}}_{4}$${\mathrm{BO}}_{0.2}$ (${\mathit{T}}_{\mathit{c}}$\ensuremath{\approxeq}12.5 K) and ${\mathrm{YNi}}_{2}$${\mathrm{B}}_{3}$${\mathrm{O}}_{0.2}$ (${\mathit{T}}_{\ma…

Rare-earth and actinide compoundsIron-based superconductors researchSuperconductivity in MgB2 and Alloys

Stereocomplex formation between enantiomeric poly(lactic acid). VIII. Complex fibers spun from mixed solution of poly(D‐lactic acid) and poly(L‐lactic acid)

Hideto Tsuji、Yoshito Ikada、Suong‐Hyu Hyon 等 5 位作者1994-01-10Journal of Applied Polymer Science

Abstract To obtain poly(lactic acid) (PLA) complex fibers, spinning was performed by wet and dry methods from 5–10 g/dL chloroform solutions of poly(D‐lactic acid) (PDLA) and poly(L‐lactic), both with a viscosity‐average molecular weight of 3 × 10 5 . The dope was extruded from a monohole nozzle into coagulation baths…

biodegradable polymer synthesis and propertiesMicroplastics and Plastic PollutionCarbon dioxide utilization in catalysis

Synthesis and Characterization of Molybdenum Carbide Clusters Mo n C 4 n , ( n = 1 to 4)

C. Jin、R. E. Haufler、Robert L. Hettich 等 8 位作者1994-01-07Science

Laser radiation (XeCl laser, 308-nanometer wavelength) focused into a cell containing Mo(CO)(6) vapor produced ultrafine particles in the extended waist of the laser beam. Negative ion mass spectrometry revealed molybdenum carbide cluster ions with a stoichiometry MonC4n (n = 1 to 4). The MonC4n(-) (n = 2 to 4) ions a…

Advanced Chemical Physics StudiesDiamond and Carbon-based Materials ResearchIon-surface interactions and analysis

Direct observation of better hydration at the N terminus of an alpha-helix with glycine rather than alanine as the N-cap residue.

Yehouda Harpaz、Nadia elMasry、A.R. Fersht 等 4 位作者1994-01-04Proceedings of the National Academy of Sciences

The structural basis for the stability of N termini of helices has been analyzed by thermodynamic and crystallographic studies of three suitably engineered mutants of the barley chymotrypsin inhibitor 2 with Ser, Gly, or Ala at the N-cap position (residue 31). Each mutant has a well-organized shell of hydration of the…

RNA and protein synthesis mechanismsMicrobial Metabolic Engineering and BioproductionEnzyme Structure and Function

The crystal structure of a mutant protein with altered but improved hydrophobic core packing.

Wendell A. Lim、A.E. Hodel、Robert T. Sauer 等 4 位作者1994-01-04Proceedings of the National Academy of Sciences

The dense packing observed in protein interiors appears to be crucial for stabilizing the native structure--even subtle internal substitutions are usually destabilizing. Thus, steric complementarity of core residues is thought to be an important criterion for "inverse folding" predictive methods, which judge whether a…

Protein Structure and DynamicsGlycosylation and Glycoproteins ResearchEnzyme Structure and Function

Direct measurement of forces between self-assembled proteins: temperature-dependent exponential forces between collagen triple helices.

Sergey Leikin、D C Rau、V. Adrian Parsegian1994-01-04Proceedings of the National Academy of Sciences

We report direct measurements of force vs. separation between self-assembled proteins. These forces are observed between collagen triple helices in native and reconstituted fibers. They are a combination of a short-range repulsion, which varies exponentially over at least five decay lengths, and an inferred, longer-ra…

Protein Structure and DynamicsCellular Mechanics and InteractionsCollagen: Extraction and Characterization

Raman and low frequency Raman spectroscopy of lead, zinc and barium metaphosphate glasses doped with Eu3+ions

P.P. Proulx、G. Cormier、J. A. Capobianco 等 5 位作者1994-01-03Journal of Physics Condensed Matter

An investigation of low-frequency inelastic scattering (LOFIS) and pre-resonant Raman spectroscopy has revealed the role of the modifying cations, Ba 2+ , Zn 2+ and Pb 2+ on the bonding properties of the Eu-O bond in Ba(PO 3 ) 2 , Zn(PO 3 ) 2 , and Pb(PO 3 ) 2 glasses. Analysis of the results has shown that the electr…

Luminescence Properties of Advanced MaterialsGlass properties and applicationsPhase-change materials and chalcogenides

The interaction of sulfenamide accelerators with sulfur, ZNO, and stearic acid in the absence of rubber

M. H. S. Gradwell、W. J. McGill1994-01-03Journal of Applied Polymer Science

Abstract The interaction of sulfur, ZnO, stearic acid, and the three sulfenamide accelerators N ‐cyclohexylbenzothiazole sulfenamide (CBS), 2‐(4‐morpholinothio) benzothiazole (MOR), and 2‐ t ‐butylaminobenzothiazole sulfenamide (TBBS) were investigated by differential scanning calorimetry in the absence of rubber. In…

Synthesis and properties of polymersSulfur-Based Synthesis TechniquesThermal and Kinetic Analysis

Heat sealing of semicrystalline polymer films. III. Effect of corona discharge treatment of LLDPE

James M. Farley、Prasadarao Meka1994-01-03Journal of Applied Polymer Science

Abstract The effects of corona‐discharge treatment (CDT) of commercial polyethylene (PE) Linear low‐density PE (LLDPE) were studied with special emphasis on the heat‐seal behavior of treated films. A range of treat levels, representative of those used in industry, was obtained by varying the applied power to a commerc…

Surface Modification and SuperhydrophobicityHigh voltage insulation and dielectric phenomenaElectrostatic Discharge in Electronics

Selective poling of nonlinear optical polymer films by means of a monoenergetic electron beam

G.M. Yang、S. Bauer‐Gogonea、G. M. Sessler 等 7 位作者1994-01-03Applied Physics Letters

Electron beams with an energy of 10 keV were employed for selectively poling only the lower part of a typical nonlinear optical guest/host polymer at a temperature of 90 °C. The resulting dipole orientation was examined by means of electro-optical measurements and thermally stimulated depolarization, while the nonunif…

Advanced Fiber Laser TechnologiesNonlinear Optical Materials ResearchPhotorefractive and Nonlinear Optics

The thermal decomposition of sulfenamide accelerators

M. H. S. Gradwell、W. J. McGill1994-01-03Journal of Applied Polymer Science

Abstract The thermal decomposition of three sulfenamide accelerators N ‐cyclohexylbenzothiazole sulfenamide (CBS), 2‐(4‐morpholinothio) benzothiazole (MOR) and 2‐ t ‐butylaminobenzothiazole sulfenamide (TBBS) were investigated by differential scanning calorimetry. The sulfenamides decompose rapidly at 210–220°C, yield…

Synthesis and properties of polymersThermal and Kinetic AnalysisChemical Reactions and Mechanisms