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Multiple Areas of Magnetic Bistability in the Topological Ferrimagnet [Co3(NC5H3(CO2)2-2,5)2(μ3-OH)2(OH2)2]

Simon M. Humphrey、Paul T. Wood2004-09-24Journal of the American Chemical Society

Hydrothermal reaction of CoCl2 with the potassium salt of pyridine-2,3-dicarboxylic acid and excess base yields [Co3(NC5H3(CO2)2-2,5)2(mu3-OH)2(OH2)2], which has a three-dimensional structure based on hydroxide-bridged triangular chains. The magnetic behavior of this compound shows the presence of three distinct regio…

Magnetism in coordination complexesAdvanced Condensed Matter PhysicsMolecular spectroscopy and chirality

Properties and Structure of Nitric Acid Oxidized Single Wall Carbon Nanotube Films

Xiefei Zhang、T. V. Sreekumar、Tao Liu 等 4 位作者2004-09-24The Journal of Physical Chemistry B

Single wall carbon nanotube films (bucky paper ) have been prepared using aqueous dispersions containing 0, 3, 6, and 10 M nitric acid. With increasing nitric acid concentration, film tensile strength increased from 10 to 74 MPa, tensile modulus from 0.8 to 5.0 GPa, while in-plane dc electrical conductivity decreased…

Carbon Nanotubes in CompositesGraphene research and applicationsConducting polymers and applications

Magnetic Percolation in Diluted Magnetic Semiconductors

Lars Bergqvist、Olle Eriksson、J. Kudrnovský 等 6 位作者2004-09-24OpenAlex

We demonstrate that the magnetic properties of diluted magnetic semiconductors are dominated by short ranged interatomic exchange interactions that have a strong directional dependence. By combining first principles calculations of interatomic exchange interactions with a classical Heisenberg model and Monte Carlo sim…

ZnO doping and propertiesTheoretical and Computational PhysicsMagnetic and transport properties of perovskites and related materials

How Reproducible Are Dynamic Heterogeneities in a Supercooled Liquid?

Asaph Widmer‐Cooper、Peter Harrowell、Herb Fynewever2004-09-24OpenAlex

The particle dynamics in a liquid exhibits a transient spatial distribution of dynamic heterogeneities. The relationship between this kinetic structure and the underlying particle configuration remains an outstanding problem. In this Letter, we present a general simulation technique for identifying the features of the…

Material Dynamics and PropertiesSurfactants and Colloidal SystemsThermodynamic properties of mixtures

Well-Defined Calcium Initiators for Lactide Polymerization

Malcolm H. Chisholm、Judith C. Gallucci、Khamphee Phomphrai2004-09-24OpenAlex

A series of monomeric amide or aryloxide complexes of the form LCaX, where L = CH[CMeNC(6)H(3)-2,6-](2), CH[CMeNC(6)H(4)-2-OMe](2), a bulky tris-pyrazolyl borate, Tp(iPr) or Tp(tBu) or 9-BBN-pz(2) and X = N(SiMe(3))(2) or OC(6)H(3)-2,6-, has been prepared and characterized and investigated in the ring-opening polymeri…

Organometallic Complex Synthesis and Catalysisbiodegradable polymer synthesis and propertiesCarbon dioxide utilization in catalysis

Fluorescence Emission from Dendrimers and Its pH Dependence

Dongjun Wang、Toyoko Imae2004-09-24OpenAlex

A strong fluorescence emission was observed from different kinds of dendrimers under acidic condition. There was a remarkable difference in fluorescence properties between second and fourth generation NH2-terminated poly(amido amine) dendrimers. It can be assumed that the backbone of the dendrimer played the key role…

Advanced biosensing and bioanalysis techniquesLuminescence and Fluorescent MaterialsDendrimers and Hyperbranched Polymers

Bulk-solvent and hydration-shell fluctuations, similar to α- and β-fluctuations in glasses, control protein motions and functions

Paul W. Fenimore、Hans Frauenfelder、Benjamin H. McMahon 等 4 位作者2004-09-24OpenAlex

The concept that proteins exist in numerous different conformations or conformational substates, described by an energy landscape, is now accepted, but the dynamics is incompletely explored. We have previously shown that large-scale protein motions, such as the exit of a ligand from the protein interior, follow the di…

Protein Structure and DynamicsMaterial Dynamics and PropertiesHemoglobin structure and function

Crystallization and preliminary crystallographic analysis of 3′-aminoglycoside kinase type IIIa complexed with a eukaryotic protein kinase inhibitor, CKI-7

D.H. Fong、Albert M. Berghuis2004-09-23Acta Crystallographica Section D Biological Crystallography

3'-Aminoglycoside kinase type IIIa [APH(3')-IIIa] catalyzes the transfer of gamma-phosphate from ATP to the 3'-hydroxyl of many aminoglycoside antibiotics, abolishing their bactericidal effects. Despite very low sequence identity, APH(3')-IIIa and eukaryotic protein kinases share structural and functional similarities…

Bacterial Genetics and BiotechnologyRNA and protein synthesis mechanismsEnzyme Structure and Function

Crystallization and preliminary X-ray diffraction studies of a fungal hydrolase fromOphiostoma novo-ulmi

Michail N. Isupov、Amanda A. Brindley、Edward J. Hollingsworth 等 6 位作者2004-09-23Acta Crystallographica Section D Biological Crystallography

Dutch elm disease fungus Ophiostoma novo-ulmi contains a hydrolase activity which catalyses the resolution of racemic ethyl naproxen to the corresponding acid. The recombinant enzyme has been crystallized by the vapour-diffusion method in two crystal forms. The crystals of the first form belong to space group P2(1)2(1…

Microbial Metabolic Engineering and BioproductionEnzyme Structure and FunctionEnzyme Production and Characterization

Brillouin light scattering study of surface acoustic phonons in p+porous silicon layers

G. Todd Andrews、M. J. Clouter、J. Żuk2004-09-23Semiconductor Science and Technology

Brillouin light scattering experiments were carried out on porous silicon layers fabricated from [111]-oriented p-type crystalline silicon substrates with resistivity 0.01 Ω cm. The thickness and porosity of the layers ranged from 1.6 to 11.40 µm and 0.25 to 0.40, respectively. The only Brillouin peaks evident in the…

Semiconductor materials and devicesSilicon Nanostructures and PhotoluminescenceNanowire Synthesis and Applications

Effect of Ru substitution for Ni on the superconductivity inMgCNi3−xRux

Tomasz Klimczuk、V. B. Gupta、G. Lawes 等 5 位作者2004-09-23Physical Review B

The superconductor $\mathrm{Mg}\mathrm{C}{\mathrm{Ni}}_{3}$ has been chemically doped by partial substitution of Ru for Ni in the solid solution $\mathrm{Mg}\mathrm{C}{\mathrm{Ni}}_{3\ensuremath{-}x}{\mathrm{Ru}}_{x}$ for $0<x<0.5$. Magnetic and specific heat measurements show that the Sommerfeld parameter $({\e…

Rare-earth and actinide compoundsSuperconductivity in MgB2 and AlloysThermal Expansion and Ionic Conductivity

Structure of the CoA transferase from pig heart to 1.7 Å resolution

Abbie M. Coros、Lora Swenson、William T. Wolodko 等 4 位作者2004-09-23Acta Crystallographica Section D Biological Crystallography

Succinyl-CoA:3-ketoacid CoA transferase (SCOT; EC 2.8.3.5) activates the acetoacetate in ketone bodies by transferring the CoA group from succinyl-CoA to acetoacetate to produce acetoacetyl-CoA and succinate. In the reaction, a glutamate residue at the active site of the enzyme forms a thioester bond with CoA and in t…

Microbial Metabolic Engineering and BioproductionEnzyme Structure and FunctionBiochemical and Molecular Research

Acidophilic adaptations in the structure ofAcetobacter aceti N5-carboxyaminoimidazole ribonucleotide mutase (PurE)

Ethan C. Settembre、Johnathan Chittuluru、Christopher P. Mill 等 5 位作者2004-09-23Acta Crystallographica Section D Biological Crystallography

The crystal structure of Acetobacter aceti PurE was determined to a resolution of 1.55 A and is compared with the known structures of the class I PurEs from a mesophile, Escherichia coli, and a thermophile, Thermotoga maritima. Analyses of the general factors that increase protein stability are examined as potential e…

Enzyme Structure and FunctionMetal-Catalyzed Oxygenation MechanismsPorphyrin Metabolism and Disorders

Evidence for Discrepancy between the Surface Lewis Acid Site Strength and Infrared Spectra of Adsorbed Molecules: The Case of Boria−Silica

Arnaud Travert、Alexandré Vimont、J.C. Lavalley 等 7 位作者2004-09-23The Journal of Physical Chemistry B

The acidity of amorphous B 2 O 3 −SiO 2 has been investigated by infrared spectroscopy using the following three probe molecules presenting a wide range of basic strength: pyridine, acetonitrile, and carbon monoxide. The results are compared to those obtained on γ-Al 2 O 3 . No coordination of carbon monoxide is obser…

Zeolite Catalysis and SynthesisGlass properties and applicationsChemical Synthesis and Characterization

Synthesis and Characterization of a Discotic Uranium-Containing Liquid Crystal

Jonathan L. Sessler、Wyeth B. Callaway、Stephen P. Dudek 等 5 位作者2004-09-23Inorganic Chemistry

The synthesis of several UO(2)-alaskaphyrin derivatives functionalized with aliphatic chains is described. These compounds are found to be liquid-crystalline and form columnar mesophases, as judged from polarizing optical microscopy studies, and represent the first uranium-containing discotic mesogens.

Photosynthetic Processes and MechanismsPorphyrin and Phthalocyanine ChemistryLanthanide and Transition Metal Complexes

Electron interaction in weakly confining quantum dot potentials

Peter Winkler2004-09-23International Journal of Quantum Chemistry

Abstract The electronic structure of three model potentials for quantum dots has been studied. The potentials are of finite depth and spherical symmetry and have a range between 5 to 25 nm. The sequence of electronic states differs markedly from the one familiar from atomic systems. The occurrence of high angular mome…

Quantum Dots Synthesis And PropertiesQuantum and electron transport phenomenaSurface and Thin Film Phenomena

How Fluorous Is Poly(2,2-bis(trifluoromethyl)-4,5-difluoro-1,3-dioxide-co-tetrafluoroethylene) (Teflon AF)?

Hong Zhao、Kamal Z. Ismail、Stephen G. Weber2004-09-23Journal of the American Chemical Society

We investigated poly(2,2-bis(trifluoromethyl)-4,5-difluoro-1,3-dioxide-co-tetrafluoroethylene (Teflon AF 2400, Tg = 240 degrees C), a stable and permeable fluorous polymer, as a transport/extraction medium for solutes for the first time. From the study of transport behavior of a series of solutes (in chloroform soluti…

Advanced Polymer Synthesis and CharacterizationMembrane Separation and Gas TransportSynthesis and properties of polymers

Phosphoenolpyruvate- and ATP-Dependent Dihydroxyacetone Kinases: Covalent Substrate-Binding and Kinetic Mechanism,

Luis F. García‐Alles、Christian Siebold、Therese Lüthi Nyffeler 等 8 位作者2004-09-23Biochemistry

Dihydroxyacetone (Dha) kinases are a sequence-conserved family of enzymes, which utilize two different phosphoryldonors, ATP in animals, plants, and some bacteria, and a multiphosphoprotein of the phosphoenolpyruvate carbohydrate phosphotransferase system (PTS) in most bacteria. Here, we compare the PTS-dependent kina…

Enzyme Structure and FunctionMetabolism, Diabetes, and CancerAmino Acid Enzymes and Metabolism

Long‐term imaging effects in rat liver after a single injection of an iron oxide nanoparticle based MR contrast agent

Karen Briley‐Sæbø、Svein‐Olaf Hustvedt、Anita Haldorsen 等 4 位作者2004-09-23Journal of Magnetic Resonance Imaging

PURPOSE: To investigate the duration of liver R2* enhancement and pharmacokinetics following administration of an iron oxide nanoparticle in a rat model. MATERIALS AND METHODS: Rats were injected with 0, 1, 2, or 5 mg Fe/kg of NC100150 Injection, and quantitative in vivo 1/T2* liver measurements were obtained between…

Nanoparticle-Based Drug DeliveryIron Metabolism and DisordersCharacterization and Applications of Magnetic Nanoparticles

Analysis of Doubly Clamped Nanotube Devices in the Finite Deformation Regime

Nicola M. Pugno、Changhong Ke、Horacio D. Espinosa2004-09-23Journal of Applied Mechanics

In this paper, a nonlinear theory applicable to the design of nanotube based devices is presented. The role of finite kinematics for a doubly clamped nanotube device is investigated. In particular, we analyze the continuous deformation and instability (pull in) of a clamped-clamped nanotube suspended over an electrode…

Carbon Nanotubes in CompositesForce Microscopy Techniques and ApplicationsMechanical and Optical Resonators