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Enhancement of magnetic properties of nanocomposite Pr2Fe14B/α-Fe magnets by small substitution of Dy for Pr

Zhongmin Chen、Hideyuki Okumura、G. C. Hadjipanayis 等 4 位作者2001-02-15Journal of Applied Physics

Nanocomposite (Pr,Dy)2Fe14B/α-Fe magnets with compositions Pr8−xDyxFe86B6 (x=0, 0.5, 1, 1.5, and 2) have been synthesized by melt spinning using low wheel speeds in the range from 18 to 21.7 m/s. It has been found that the coercivity is significantly increased by Dy substitution. An optimum coercivity of 6.6 kOe is ob…

Magnetic properties of thin filmsMagnetic Properties and ApplicationsMagnetic Properties of Alloys

A New, Efficient Route to Titanium-Silsesquioxane Epoxidation Catalysts Developed by Using High-Speed Experimentation Techniques

Paolo P. Pescarmona、Jan C. van der Waal、Ian E. Maxwell 等 4 位作者2001-02-15Angewandte Chemie International Edition

High-speed experimentation techniques have been applied in the synthesis and testing of silsesquioxane-based titanium catalysts (see picture) for the epoxidation of alkenes. Different solvents and organotrichlorosilanes were employed in the optimization of the hydrolytic condensation of silanes to open silsesquioxane…

Metal and Thin Film MechanicsSynthesis and characterization of novel inorganic/organometallic compoundsSilicone and Siloxane Chemistry

Highly Reactive SmII Macrocyclic Clusters: Precursors to N2 Reduction

Ganesan Mani、Sandro Gambarotta、Glenn P. A. Yap2001-02-15Angewandte Chemie International Edition

Transamination reactions of [{(Me3Si)2N}2Sm(thf)2] with the dianion of either 1,1-di-(α-pyrrolyl)cyclohexane or diphenyl dipyrromethane led to the octanuclear complex shown in the picture and the hexanuclear complex [{[Ph2C(α-C4H3N)2]Sm}6(thf)3], respectively. Both clusters possess flat macrocyclic structures and reac…

Organometallic Complex Synthesis and CatalysisMagnetism in coordination complexesMetalloenzymes and iron-sulfur proteins

Conductivity spectra of sodium fluorozirconate glasses

A. Ghosh、M. Sural2001-02-15The Journal of Chemical Physics

We have reported conductivity spectra at different temperatures for fluoride glasses of compositions 0.50ZrF4–(0.40−x)BaF2–0.10YF3–xNaF in the frequency range from 10 Hz to 2 MHz. We have analyzed the spectra using conductivity formalism and obtained the frequency exponent, concentration, and hopping frequency of char…

Material Dynamics and PropertiesGlass properties and applicationsSolid-state spectroscopy and crystallography

Allylic Alcohol Epoxidation by Methyltrioxorhenium: A Density Functional Study on the Mechanism and the Role of Hydrogen Bonding

Cristiana Di Valentin、Remo Gandolfi、Philip Gisdakis 等 4 位作者2001-02-15Journal of the American Chemical Society

By locating all relevant transition structures with a hybrid density functional method, we explored the three most reasonable mechanisms for H2O2 epoxidation of propenol catalyzed by methyltrioxorhenium (MTO), namely: (i) coordination of propenol as lone pair donor to rhenium mono- and bis-peroxo complexes followed by…

Polyoxometalates: Synthesis and ApplicationsMetal-Catalyzed Oxygenation MechanismsOxidative Organic Chemistry Reactions

Nonlinear optical properties of LaCa_4O(BO_3)_3

John J. Adams、Christopher A. Ebbers、Kathleen I. Schaffers 等 4 位作者2001-02-15Optics Letters

We have grown LaCa(4)O (BO(3))(3) (LaCOB), an isostructural member of GdCa(4)O(BO(3))(3) (GdCOB) family and characterized its nonlinear optical properties. At 1064nm, d(eff) of 0.52+/-0.05 pm /V and an angular sensitivity of 1224+/-184(cm rad)(-1) for type I frequency doubling in LaCOB were determined relative to thos…

High-pressure geophysics and materialsCrystal Structures and PropertiesPhotorefractive and Nonlinear Optics

Nitroxide Radicals as Templating Agents in the Synthesis of Magnets Based on Three-Dimensional Oxalato-Bridged Heterodimetallic Networks

Gloria Ballester、Eugenio Coronado、Carlos Giménez‐Saiz 等 4 位作者2001-02-15Angewandte Chemie International Edition

Stable free radicals can be trapped inside a three-dimensional (3D) inorganic network. The formation of a new type of mixed-metal oxalate [MnII(H2O)CrIII(ox)3]− is induced by the presence of a cationic nitronyl nitroxide radical (rad+). The figure shows a stylized view of the 3D network ○ = Mn, • = Cr). This hybrid or…

Metal-Organic Frameworks: Synthesis and ApplicationsMagnetism in coordination complexesLanthanide and Transition Metal Complexes

Frequency-dependent specific heat of viscous silica

Peter Scheidler、Walter Kob、Arnulf Latz 等 5 位作者2001-02-15Physical review. B, Condensed matter

We apply the Mori-Zwanzig projection operator formalism to obtain an expression for the frequency dependent specific heat $c(z)$ of a liquid. By using an exact transformation formula due to Lebowitz et al., we derive a relation between $c(z)$ and $K(t),$ the autocorrelation function of temperature fluctuations in the…

Material Dynamics and PropertiesTheoretical and Computational PhysicsSpectroscopy and Quantum Chemical Studies

Atomistic modelling of radiation damage in zircon

Kostya Trachenko、Martin T. Dove、Ekhard K. H. Salje2001-02-15Journal of Physics Condensed Matter

We report the results of simulation of radiation damage in zircon structure using the molecular dynamics technique. The phases of the damage production process, including the ballistic and thermal spike phases, are detected, quantified and visualized. We find that the higher ambient temperature results in substantial…

Geological and Geochemical AnalysisHigh-pressure geophysics and materialsNuclear materials and radiation effects

Fluorinated Surfaces, Coatings, and Films

David G. Castner、David W. Grainger2001-02-15ACS symposium series

Fluorinated surfaces are sought for a number of technologies requiring low surface energy, low adhesion, chemical robustness, among other desired properties. Bulk fluorinated materials (e.g., polymers) can be used, but their relative expense and difficult processing problems preclude widespread application. Small mole…

Synthesis and properties of polymersSilicone and Siloxane Chemistry

Electron paramagnetic resonance of ferrite nanoparticles

Yu. A. Koksharov、Denis Pankratov、С. П. Губин 等 7 位作者2001-02-15Journal of Applied Physics

Three types of iron-based oxide nanoparticles (weight compositions Fe2O3, BaFe2O4, and BaFe12O19) embedded in a polyethylene matrix are studied using the electron paramagnetic resonance technique. All nanoparticles are found to be multiphase. Thermal variations of electron paramagnetic resonance spectra reveal the pre…

Magnetic properties of thin filmsMagnetic Properties and Synthesis of FerritesIron oxide chemistry and applications

Synthesis and Anionic Ring-Opening Polymerization Behavior of Amino Acid-Derived Cyclic Carbonates

Fumio Sanda、Jun Kamatani、Takeshi Endo2001-02-15Macromolecules

Synthesis and anionic ring-opening polymerization of l -serine (Ser)- and l -threonine (Thr)-based cyclic carbonates, (2-oxo[1,3]dioxan-5-yl)carbamic acid benzyl ester (Z-S-CC), (4-methyl-2-oxo[1,3]dioxan-5-yl)carbamic acid benzyl ester (Z-T-CC), and (4-methyl-2-oxo[1,3]dioxan-5-yl)carbamic acid tert -butyl ester (Boc…

biodegradable polymer synthesis and propertiesCarbon dioxide utilization in catalysisChemistry and Chemical Engineering

Large-Scale Domain Movements and Hydration Structure Changes in the Active-Site Cleft of Unligated Glutamate Dehydrogenase from Thermococcus profundus Studied by Cryogenic X-ray Crystal Structure Analysis and Small-Angle X-ray Scattering,

Masayoshi Nakasako、Testuro Fujisawa、Shin‐ichi Adachi 等 5 位作者2001-02-15Biochemistry

Here we describe the large-scale domain movements and hydration structure changes in the active-site cleft of unligated glutamate dehydrogenase. Glutamate dehydrogenase from Thermococcus profundus is composed of six identical subunits of M(r) 46K, each with two distinct domains of roughly equal size separated by a lar…

Protein Structure and DynamicsEnzyme Structure and FunctionAmino Acid Enzymes and Metabolism

Electronic structure of the 4d transition metal carbides: Dispersed fluorescence spectroscopy of MoC, RuC, and PdC

Ryan S. DaBell、Raymond G. Meyer、Michael D. Morse2001-02-15The Journal of Chemical Physics

Dispersed fluorescence studies of the diatomic molecules MoC, RuC, and PdC are reported. New states identified in MoC and RuC are the […]2δ112σ1, 3,1Δ2 states and the […]2δ312σ1, 1Δ2 state, respectively. Five states are observed by dispersed fluorescence in PdC. The ground state is found to be […]2δ412σ2, 1Σ+, with th…

Semiconductor materials and devicesDiamond and Carbon-based Materials ResearchIon-surface interactions and analysis

Left or Right, It Is a Matter of One Methylene Unit

Christopher Y. Li、Stephen Z. D. Cheng、Xin Weng 等 10 位作者2001-02-15Journal of the American Chemical Society

ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTLeft or Right, It Is a Matter of One Methylene UnitChristopher Y. Li, Stephen Z. D. Cheng, Xin Weng, Jason J. Ge, Feng Bai, John Z. Zhang, Bret H. Calhoun, Frank W. Harris, Liang-Chy Chien, and Bernard LotzView Author Information The Maurice Morton Institute and Depart…

Liquid Crystal Research AdvancementsPhotochemistry and Electron Transfer StudiesNonlinear Dynamics and Pattern Formation

Crossover criticality in ionic solutions

Krzysztof Gutkowski、M. A. Anisimov、J. V. Sengers2001-02-15The Journal of Chemical Physics

To examine the nature of criticality in ionic fluids we have analyzed experimental liquid–liquid coexistence and susceptibility data for various ionic solutions. We show that ionic fluids generally exhibit crossover or, at least, a tendency to crossover from Ising behavior asymptotically close to the critical point to…

Material Dynamics and PropertiesThermodynamic properties of mixturesNMR spectroscopy and applications

Anion-Directed Crystallization of Coordination Polymers: Syntheses and Characterization of Cu4(2-pzc)4(H2O)8(Mo8O26)·2H2O and Cu3(2-pzc)4(H2O)2(V10O28H4)·6.5H2O (2-pzc = 2-Pyrazinecarboxylate)

Li‐Min Zheng、Yongsheng Wang、Xiqu Wang 等 5 位作者2001-02-15Inorganic Chemistry

Two new copper 2-pyrazinecarboxylate (2-pzc) coordination polymers incorporating [Mo(8)O(26)](4-) and [V(10)O(28)H(4)](2-) anions were synthesized and structurally characterized: Cu(4)(2-pzc)(4))(H(2)O)(8)(Mo(8)O(26)).2H(2)O (1) and Cu(3)(2-pzc)(4)(H(2)O)(2)(V(10)O(28)H(4)).6.5H(2)O (2). Crystal data: 1, monoclinic, s…

Metal-Organic Frameworks: Synthesis and ApplicationsPolyoxometalates: Synthesis and ApplicationsVanadium and Halogenation Chemistry

Novel Pseudorotaxane-Terminated Dendrimers: Supramolecular Modification of Dendrimer Periphery

Jae Wook Lee、Young Ho Ko、Sanghyun Park 等 5 位作者2001-02-15Angewandte Chemie International Edition

Thirty-two molecular beads are threaded onto the terminal groups of a fourth-generation dendrimer (see picture). These pseudorotaxane-terminated dendrimers not only constitute a new class of topologically intriguing molecules but also provide a novel way of modifying dendrimer exteriors by noncovalent interactions.

Supramolecular Chemistry and ComplexesLuminescence and Fluorescent MaterialsDendrimers and Hyperbranched Polymers

Synthesis and Fluorescence Properties of Manisyl-Substituted Terpyridine, Bipyridine, and Phenanthroline

Jon C. Loren、Jay S. Siegel2001-02-15Angewandte Chemie International Edition

As a hybrid of two aryl motifs, that is p-anisyl and mesityl, the 4-methoxy-2,6-dimethylphenyl or “manisyl” substituent offers possibilities for both further structural elaboration as well as enhancing the solubility of the heterocyclic ligands mentioned in the title. A highlight of this work lies in the ability of th…

Molecular Sensors and Ion DetectionCatalytic Cross-Coupling ReactionsLuminescence and Fluorescent Materials

Characterization of Highly Branched Poly(methyl methacrylate) by Solution Viscosity and Viscoelastic Spectroscopy

Peter F. W. Simon、Axel H. E. Müller、Tadeusz Pakuła2001-02-15Macromolecules

Highly branched poly(methyl methacrylate) with an estimated degree of branching = 0.074 (i.e., 3.7 branchpoints per 100 monomer units) was prepared using self-condensing group transfer copolymerization (SCVCP) of methyl methacrylate (MMA) and 2-(2-methyl-1-triethylsiloxy-1-propenyloxy)ethyl methacrylate (MTSHEMA) and…

Advanced Polymer Synthesis and CharacterizationPolymer Surface Interaction StudiesDendrimers and Hyperbranched Polymers