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Dinuclear, Bishydrated GdIII Polyaminocarboxylates with a Rigid Xylene Core Display Remarkable Proton Relaxivities

Jérôme Costa、Éva Tóth、Lothar Helm 等 4 位作者2005-05-19Inorganic Chemistry

Two novel dinuclear Gd(III) complexes have been synthesized, based on a xylene core substituted with diethylenetriamine-N,N,N'',N''-tetraacetate (DTTA) chelators in para or meta position. The complexes [Gd2(pX(DTTA)2)(H2O)4]2- and [Gd2(mX(DTTA)2)(H2O)4]2- both exhibit high complex stability (log K(GdL) = 19.1 and 17.0…

Metal-Organic Frameworks: Synthesis and ApplicationsLanthanide and Transition Metal ComplexesAdvanced NMR Techniques and Applications

Electrically driven deformations of nematic gels

Kenji Urayama、Hidesato Kondo、Yūkō Arai 等 4 位作者2005-05-19Physical Review E

The electrically driven deformations of side chain nematic networks swollen by nematic solvents (nematic gels) have been investigated. The strains of freely suspended gels between electrodes were measured as a function of field strength (E) . The deformation of the gels composed of a network and solvent with identical…

Liquid Crystal Research AdvancementsHydrogels: synthesis, properties, applicationsAdvanced Materials and Mechanics

Crystal Structure ofEscherichia coliPenicillin-Binding Protein 5 Bound to a Tripeptide Boronic Acid Inhibitor: A Role for Ser-110 in Deacylation

George Nicola、Sridhar Peddi、Miglena E. Stefanova 等 6 位作者2005-05-19Biochemistry

Penicillin-binding protein 5 (PBP 5) from Escherichia coli is a well-characterized d-alanine carboxypeptidase that serves as a prototypical enzyme to elucidate the structure, function, and catalytic mechanism of PBPs. A comprehensive understanding of the catalytic mechanism underlying d-alanine carboxypeptidation and…

Bacterial Genetics and BiotechnologyRNA and protein synthesis mechanismsEnzyme Structure and Function

Compressing PEG Brushes

Tanja Drobek、Nicholas D. Spencer、Manfred Heuberger2005-05-19Macromolecules

Poly(ethylene glycol) (PEG) surface grafts are used as surface coatings that impart resistance to nonspecific protein adsorption. In this work, brushes of poly(ethylene glycol), grafted to a cationic polylysine backbone and adsorbed onto mica, were investigated with the surface forces apparatus, providing direct measu…

Polymer Surface Interaction StudiesForce Microscopy Techniques and ApplicationsAdhesion, Friction, and Surface Interactions

Effects of Polymer Architecture and Nanoenvironment in Acylation Reactions Employing Dendritic (Dialkylamino)pyridine Catalysts

Brett A. Helms、Catherine O. Liang、Craig J. Hawker 等 4 位作者2005-05-19Macromolecules

The role of architecture and nanoenvironment in the catalytic properties of dendritic polymers containing 4-(dialkylamino)pyridines was investigated in the context of acylation reactions employing sterically demanding tertiary alcohols as substrates. Fréchet-type benzyl ether and aliphatic ester dendrimers were prepar…

Advanced Polymer Synthesis and CharacterizationChemical Synthesis and AnalysisDendrimers and Hyperbranched Polymers

Crystallography and Surface Faceting of Germanium Nanowires

Tobias Hanrath、Brian A. Korgel2005-05-19Small

Key crystallographic aspects of Ge nanowires grown in a supercritical fluid were investigated by high-resolution transmission electron microscopy. The favored <110> growth direction was attributed to the crystallographic faceting of low-energy {111} and {100} planes on the initial nucleus crystal and the exposed nanow…

Semiconductor materials and devicesSilicon Nanostructures and PhotoluminescenceNanowire Synthesis and Applications

QM/MM modeling the Ras–GAP catalyzed hydrolysis of guanosine triphosphate

Bella L. Grigorenko、Alexander V. Nemukhin、Igor A. Topol 等 5 位作者2005-05-19Proteins Structure Function and Bioinformatics

The mechanism of the hydrolysis reaction of guanosine triphosphate (GTP) by the protein complex Ras-GAP (p21(ras) - p120(GAP)) has been modeled by the quantum mechanical-molecular mechanical (QM/MM) and ab initio quantum calculations. Initial geometry configurations have been prompted by atomic coordinates of a struct…

RNA and protein synthesis mechanismsEnzyme Structure and FunctionBiochemical and Molecular Research

Photocontrolled Microphase Separation of Block Copolymers in Two Dimensions

Sohei Kadota、Kenji Aoki、Shusaku Nagano 等 4 位作者2005-05-19Journal of the American Chemical Society

A novel ABA-type triblock copolymer, where A and B correspond to azobenzene (Az) containing polymethacrylate and poly(ethylene oxide) (PEO), respectively, was synthesized by atom transfer radical polymerization. Langmuir-Blodgett monolayers showed characteristic microphase separation structures depending on the isomer…

Advanced Polymer Synthesis and CharacterizationBlock Copolymer Self-AssemblyNanofabrication and Lithography Techniques

Fish-tail Effect and Irreversibility Field of (Cu,C)Ba$_{2}$Ca$_{3}$Cu$_{4}$O$_{x}$-(LiF)$_{y}$ superconductor

P. Badica、V. Sandu、G. Aldica 等 7 位作者2005-05-19arXiv

Addition of (LiF)$_{y<0.15}$, and of proper amount of (AgO)$_{z=0.45-0.8}$ as oxidizing agent, to (Cu,C)Ba$_{2}$Ca$_{3}$Cu$_{4}$O$_{10+d}$ superconductor is useful to control and shift the doping characteristics (hole density and distribution, and level of disorder) into the region where the irreversible properties, i…

Materials ScienceSuperconductivity

Preparation and Electrochemical Hydrogen Storage of Boron Nitride Nanotubes

Xinyi Chen、Xueping Gao、Hao Zhang 等 9 位作者2005-05-19The Journal of Physical Chemistry B

Boron nitride (BN) nanotubes were synthesized through chemical vapor deposition over a wafer made by a LaNi5/B mixture and nickel powder at 1473 K. Scanning electron microscopy, transmission electron microscopy, energy-dispersive spectroscopy, X-ray diffraction, and X-ray photoelectron spectroscopy were performed to c…

Hydrogen Storage and MaterialsBoron and Carbon Nanomaterials ResearchMXene and MAX Phase Materials

Electronic Transition and Energy Transfer Processes in LaPO4−Ce3+/Tb3+ Nanowires

Lixin Yu、Hongwei Song、Zhongxin Liu 等 5 位作者2005-05-19The Journal of Physical Chemistry B

Ce3+ and Tb3+ coactivated LaPO4 nanowires and micrometer rods were synthesized by hydrothermal methods. Their fluorescent spectra and dynamics were systematically studied and compared. The results indicated that the extinction coefficients of Ce3+ and Tb3+ in nanowires were higher than those in micrometer rods. The el…

Luminescence Properties of Advanced MaterialsQuantum Dots Synthesis And PropertiesGas Sensing Nanomaterials and Sensors

Sharp magnetization step across the ferromagnetic-to-antiferromagnetic transition in dopedCeFe2alloys

S. B. Roy、M. K. Chattopadhyay、P. Chaddah 等 4 位作者2005-05-19Physical Review B

Very sharp magnetization step is observed across the field-induced antiferromagnetic-to-ferromagnetic transition in various doped $\mathrm{Ce}{\mathrm{Fe}}_{2}$ alloys, when the measurement is performed below $5\phantom{\rule{0.3em}{0ex}}\mathrm{K}$. In the higher temperature regime $(T&gt;5\phantom{\rule{0.3em}{0ex}}…

Magnetic and transport properties of perovskites and related materialsRare-earth and actinide compoundsMagnetic Properties of Alloys

Spin-lattice relaxation of Mn-ions in ZnMnSe/ZnBeSe quantum wells measured under pulsed photoexcitation

M. K. Kneip、D. R. Yakovlev、M. Bayer 等 9 位作者2005-05-19arXiv

The dynamics of spin-lattice relaxation of the Mn-ions in (Zn,Mn)Se-based diluted-magnetic-semiconductor quantum wells is studied by time-resolved photoluminescence. The spin-lattice relaxation time varies by five orders of magnitude from 10-3 down to 10-8 s, when the Mn content increases from 0.4 up to 11%. Free carr…

Materials Science

Study of electromagnetic wave propagation in active medium and the equivalent Schrodinger equation with energy-dependent complex potential

H. Bahlouli、A. D. Alhaidari、A. Al-Zahrani 等 4 位作者2005-05-19arXiv

We study the massless limit of the Klein-Gordon (K-G) equation in 1+1 dimensions with static complex potentials as an attempt to give an alternative, but equivalent, representation of plane electromagnetic (em) wave propagation in active medium. In the case of dispersionless em medium, the analogy dictates that the po…

cond-mat.dis-nnMaterials Science

First-principles study of ferroelectricity and isotope effects in H-bondedKH2PO4crystals

S. Koval、Jorge Kohanoff、J. Lasave 等 5 位作者2005-05-19Physical Review B

By means of extensive first-principles calculations we studied the ferroelectric phase transition and the associated isotope effect in $\mathrm{K}{\mathrm{H}}_{2}\mathrm{P}{\mathrm{O}}_{4}$ (KDP). Our calculations revealed that the spontaneous polarization of the ferroelectric phase is due to electronic charge redistr…

Crystallography and molecular interactionsNonlinear Optical Materials ResearchSolid-state spectroscopy and crystallography

Simple Synthesis of Hierarchically Ordered Mesocellular Mesoporous Silica Materials Hosting Crosslinked Enzyme Aggregates

Jinwoo Lee、Jungbae Kim、Jaeyun Kim 等 13 位作者2005-05-19Small

Hierarchically ordered mesocellular mesoporous silica materials (HMMS) were synthesized using a single structure-directing agent. The mesocellular pores are synthesized without adding any pore expander; the pore walls are composed of SBA-15 type mesopores. Small-angle X-ray scattering revealed the presence of uniform…

Supercapacitor Materials and FabricationElectrochemical sensors and biosensorsMesoporous Materials and Catalysis

Soft X-ray Resonant Magnetic Scattering Studies on Fe/CoO Exchange Bias System

Florin Radu、Alexei Nefedov、Johannes Grabis 等 6 位作者2005-05-19arXiv

We have used soft X-ray Resonant Magnetic Scattering (XRMS) to search for the presence of an effective ferromagnetic moment belonging to the antiferromagnetic (AF) layer which is in close contact with a ferromagnetic (F) layer. Taking advantage of the element specificity of the XRMS technique, we have measured hystere…

Materials Science

Influence of external factors on dielectric permittivity of Rochelle salt: humidity, annealing, stresses, electric field

A. G. Slivka、V. M. Kedyulich、R. R. Levitskii 等 6 位作者2005-05-19arXiv

The present work contains results of experimental investigation of external factors, such as dessicating/wetting, thermal annealing, uniaxial and hydrostatic pressures on dielectric permittivity of Rochelle salt crystals. The obtained results are compared with available literature data. A conslusion is made that the d…

Materials Science

Nucleation and growth of catalyst-free ZnO nanostructures

Jai Singh、Anchal Srivastava、R. S. Tiwari 等 4 位作者2005-05-19arXiv

This paper deals with the investigations on the nucleation and growth of ZnO nanostructures in a catalyst free synthesis. The ZnO nanostructures have been formed by evaporation of Zn (99.99%) in O_2 and Ar atmosphere in single zone furnace under two temperature regions, region A (~1173-1073K) and region B (~873-773K).…

Materials Science

Wet Electrons at the H 2 O/TiO 2 (110) Surface

Ken Onda、Bin Li、Jin Zhao 等 6 位作者2005-05-19Science

At interfaces of metal oxide and water, partially hydrated or "wet-electron" states represent the lowest energy pathway for electron transfer. We studied the photoinduced electron transfer at the H2O/TiO2(110) interface by means of time-resolved two-photon photoemission spectroscopy and electronic structure theory. At…

Advanced Photocatalysis TechniquesElectrochemical Analysis and ApplicationsElectronic and Structural Properties of Oxides