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Pronounced Hydrogel Formation by the Self-Assembled Aggregates of N-Alkyl Disaccharide Amphiphiles

Santanu Bhattacharya、Subhajit Acharya1999-11-10Chemistry of Materials

Six disaccharide amphiphiles were synthesized and their hydrogel-forming behavior was extensively studied. These amphiphiles were based on maltose and lactose. Since the gels formed from some of these systems showed the ability to “trap” water molecules upon gelation, these gels were described as “hydrogels”. When the…

Lipid Membrane Structure and BehaviorGlycosylation and Glycoproteins ResearchSupramolecular Self-Assembly in Materials

Strongly Enhanced Curie Temperature in Carbon-Doped Mn5Ge3 Films

M. Gajdzik、C. Suergers、M. Kelemen 等 4 位作者1999-11-10arXiv

The structural and magnetic properties of Mn5Ge3Cx films prepared at elevated substrate temperatures TS are investigated. In particular, films with x >= 0.5 and TS = 680 K exhibit a strongly enhanced Curie temperature TC = 440 K compared to Mn5Ge3 with TC = 304 K. Structural analysis of these films suggests that the c…

Materials Science

Ordered Deposition of Inorganic Clusters from Micellar Block Copolymer Films

Joachim P. Spatz、Stefan Mößmer、Christoph Hartmann 等 9 位作者1999-11-10OpenAlex

A method is presented for generating quasiregular arrays of nanometer-sized noble metal and metal oxide clusters on flat substrates by the use of a polymer template. The approach is of general applicability to other metals and various oxides. In the first step, polymeric micelles with a polar core were generated by di…

Polymer Surface Interaction StudiesBlock Copolymer Self-Assemblynanoparticles nucleation surface interactions

X-ray structural characterization, Raman and thermal analysis of LiNH4SO4above room temperature

Xavier Soláns、J. Mata、Teresa Calvet 等 4 位作者1999-11-09Journal of Physics Condensed Matter

Results are presented of a detailed x-ray diffraction, Raman and thermal analysis study of the structural phase transitions in LiNH 4 SO 4 carried out in the temperature range 298-600 K. Either two or just one phase transition was recorded in the temperature range between 335 and 461 K, depending on the warming proces…

Crystallography and molecular interactionsCrystal Structures and PropertiesSolid-state spectroscopy and crystallography

Novel three-dimensional magnetic ordering in the quantum spin system NH4CuCl3

Budhy Kurniawan、Masayasu Ishikawa、T. Kato 等 6 位作者1999-11-09Journal of Physics Condensed Matter

Low-temperature specific heat and magnetization measurements have been performed on the quantum spin system NH 4 CuCl 3 which has magnetization plateaus at one-quarter and three-quarters of the saturation magnetization. It is found that the present system undergoes three-dimensional magnetic ordering at T N = 1.3 K. I…

Organic and Molecular Conductors ResearchSolid-state spectroscopy and crystallography

<title>Magnetoelectric materials: some recent results and possible applications</title>

S. V. Suryanarayana、A. Srinivas、Reetendra Singh1999-11-09Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE

The magnetoelectric (ME) materials exhibit ferroelectric/ferrielectric/antiferroelectric properties in combination with ferromagnetic/ferrimagnetic/antiferromagnetic properties. Under the action of external magnetic field, such materials would show electric polarizations, while the external electric field would induce…

Multiferroics and related materials

Crystal structure of Bacillus subtilis YabJ, a purine regulatory protein and member of the highly conserved YjgF family

Sangita C. Sinha、Pekka Rappu、Stephan Lange 等 6 位作者1999-11-09Proceedings of the National Academy of Sciences

The yabJ gene in Bacillus subtilis is required for adenine-mediated repression of purine biosynthetic genes in vivo and codes for an acid-soluble, 14-kDa protein. The molecular mechanism of YabJ is unknown. YabJ is a member of a large, widely distributed family of proteins of unknown biochemical function. The 1.7-A cr…

Bacterial Genetics and BiotechnologyRNA and protein synthesis mechanismsEnzyme Structure and Function

Novel Synthesis of Monodispersed Pd/Ni Nanoparticles

Toshiharu Teranishi、Mikio Miyake1999-11-09Chemistry of Materials

The Ni atoms are deposited on the surface of the monodispersed Pd nanoparticles of 25 Å in size (magic number = 561) by reducing (CH3COO)2Ni·4H2O in 1-propanol under N2 at Ni/Pd molar ratios of 1/561 to 561/561 to obtain a series of Pd/Ni nanoparticles. The band structure of the Pd/Ni nanoparticles (Ni/Pd = 38/561) is…

Gold and Silver Nanoparticles Synthesis and ApplicationsQuantum Dots Synthesis And PropertiesMolecular Junctions and Nanostructures

Effect of Compositional Fluctuations on the Phase Transitions in (Nd1/2Sr1/2)MnO3

Patrick M. Woodward、D. E. Cox、Thomas Vogt 等 5 位作者1999-11-09Chemistry of Materials

High-resolution synchrotron X-ray and neutron powder diffraction techniques have been used to investigate the structural and magnetic phase transitions in two polycrystalline samples with nominal composition (Nd 0.5 Sr 0.5 )MnO 3 . The first sample separates into three coexisting macroscopic phases at low temperature:…

High-pressure geophysics and materialsMagnetic and transport properties of perovskites and related materialsAdvanced Condensed Matter Physics

Entrapment of Iodine with Cyclodextrins: Potential Application of Cyclodextrins in Nuclear Waste Management

Lajos Szente、Éva Fenyvesi、József Szejtli1999-11-09Environmental Science & Technology

Cyclodextrins form inclusion complexes with iodine, which makes them candidates for iodine-sorption from nuclear waste gases. In model experiments it was shown that cyclodextrin-containing aqueous solutions and cross-linked cyclodextrin polymers were selective and effective iodine absorbers. Especially the α-cyclodext…

Covalent Organic Framework ApplicationsBoron Compounds in ChemistryNeonatal Health and Biochemistry

Synthesis and Characterization of Nanoscopic Entities Based on Poly(caprolactone)-Grafted Cadmium Sulfide Nanoparticles

Géraldine Carrot、Stefan Scholz、C. J. G. Plummer 等 5 位作者1999-11-09Chemistry of Materials

Nanosized CdS clusters have been synthesized using polyester chains with a thiol end group as a covalently attached colloidal stabilizer. Clusters were grown through the reaction of thiourea with cadmium acetate, which was in competition with surface stabilization due to the tethered poly(caprolactone) (PCL) chains. T…

Quantum Dots Synthesis And PropertiesChalcogenide Semiconductor Thin FilmsNanocluster Synthesis and Applications

The dielectric properties of random R - C networks as an explanation of the `universal' power law dielectric response of solids

D. P. Almond、Baruch Vainas1999-11-09Journal of Physics Condensed Matter

Simulations of the AC electrical characteristics of 2D square networks randomly filled with resistors or capacitors exhibit many features in common with experimental dielectric responses of solids. These include the `universal' fractional power law dispersions in permittivity and dielectric loss characterized by the C…

Material Dynamics and PropertiesAcoustic Wave Phenomena ResearchElectrostatics and Colloid Interactions

When Gold Is Not Noble: Nanoscale Gold Catalysts

A. Sánchez、Stéphane Abbet、Ueli Heiz 等 7 位作者1999-11-09OpenAlex

While inert as bulk material, nanoscale gold particles dispersed on oxide supports exhibit a remarkable catalytic activity. Temperature-programmed reaction studies of the catalyzed combustion of CO on size-selected small monodispersed Au n ( n ≤ 20) gold clusters supported on magnesia, and first-principle simulations,…

Catalytic Processes in Materials ScienceNanocluster Synthesis and Applicationsnanoparticles nucleation surface interactions

Elaboration, characterization and aging effects of porous silicon microcavities formed on lightly p-type doped substrates

Viviana Mulloni、Cláudio Mazzoleni、Lorenzo Pavesi1999-11-08Semiconductor Science and Technology

In this paper we present and discuss the realization and optical characterization of porous silicon microcavities formed on p - -type doped substrates. We produce porous silicon microcavities with a very narrow bandwidth (5.5 nm) and a good ratio of the peak to background emission, reaching at the same time a high emi…

Semiconductor materials and devicesSilicon Nanostructures and PhotoluminescenceNanowire Synthesis and Applications

Evolution of density fluctuations to lamellar crystals in linear polyethylene

Yvonne A. Akpalu、Eric J. Amis1999-11-08The Journal of Chemical Physics

Structure formation during the isothermal crystallization of a linear polyethylene (Mw=32 100 g/mol, Mw/Mn=1.1) has been monitored by simultaneous real time small-angle x-ray scattering (SAXS) and wide angle x-ray scattering (WAXS) with synchrotron radiation. Changes in the crystalline and amorphous scattering in WAXS…

Polymer crystallization and propertiesMaterial Dynamics and PropertiesPolymer Nanocomposites and Properties

T= 0 partition functions for Potts antiferromagnets on square lattice strips with (twisted) periodic boundary conditions

Norman Biggs、Robert Shrock1999-11-08Journal of Physics A Mathematical and General

We present exact calculations of the zero-temperature partition function for the q -state Potts antiferromagnet (or, equivalently, the chromatic polynomial) for two families of arbitrarily long strip graphs of the square lattice with periodic boundary conditions in the transverse direction and (i) periodic and (ii) tw…

Physics of Superconductivity and MagnetismTheoretical and Computational PhysicsQuasicrystal Structures and Properties

Selective-area and lateral overgrowth of chromium dioxide (CrO2) films by chemical vapor deposition

A. Gupta、X. W. Li、Supratik Guha 等 4 位作者1999-11-08Applied Physics Letters

Selective-area growth has been utilized to deposit chromium dioxide (CrO2) films in specific regions of a prepatterned surface using atmospheric pressure chemical vapor deposition from CrO3 precursor. For films deposited on single crystal TiO2 substrates covered with patterned SiO2 thin film, epitaxial growth occurs s…

ZnO doping and propertiesMetal and Thin Film MechanicsHeusler alloys: electronic and magnetic properties

Energy levels in metal oxide semiconductor quantum dots in water-based colloids

Fanyao Qu、P.C. Morais1999-11-08The Journal of Chemical Physics

The three-dimensional Schrödinger and Poisson’s equations are used to calculate the conduction band profile, energy levels, and Fermi energy of negatively charged semiconductor quantum dots. The calculation is carried out self-consistently within the frame of the finite-difference method. Assuming the effective mass o…

Advanced biosensing and bioanalysis techniquesQuantum Dots Synthesis And PropertiesCopper-based nanomaterials and applications