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Chromatographic Purification for the Determination of Dissolved Silicon Isotopic Compositions in Natural Waters by High-Resolution Multicollector Inductively Coupled Plasma Mass Spectrometry

Emma Engström、Ilia Rodushkin、Douglas C. Baxter 等 4 位作者2005-11-25Analytical Chemistry

A procedure is described for accurate Si isotope ratio measurements by multicollector inductively coupled plasma mass spectrometry (MC-ICPMS). Dissolved silicon was preconcentrated and separated from other elements present in natural surface waters using anion-exchange chromatography. The optimized procedure provides…

Geochemistry and Elemental AnalysisDiatoms and Algae ResearchSilicon Effects in Agriculture

Relation between Solvent and Protein Dynamics as Studied by Dielectric Spectroscopy

Helén Jansson、R.G. Bergman、Jan Swenson2005-11-25The Journal of Physical Chemistry B

We present results obtained by dielectric spectroscopy in wide frequency (10(-2)-10(9) Hz) and temperature ranges on human hemoglobin in the three different solvents water, glycerol, and methanol, at a solvent level of 0.8 g of solvent/g of protein. In this broad frequency region, there are motions on several time-sca…

Protein Structure and DynamicsMaterial Dynamics and PropertiesSpectroscopy and Quantum Chemical Studies

Dynamic heterogeneity and non-Gaussian behaviour in a model supercooled liquid

M. Scott Shell、Pablo G. Debenedetti、Frank H. Stillinger2005-11-25Journal of Physics Condensed Matter

We use a recently derived reformulation of the diffusion constant (Stillinger and Debenedetti 2005 J. Phys. Chem. B 109 6604) to investigate heterogeneous dynamics and non-Gaussian diffusion in a binary Lennard-Jones mixture. Our work focuses on the joint probability distribution of particles with velocity v 0 at time…

Phase Equilibria and ThermodynamicsMaterial Dynamics and PropertiesThermodynamic properties of mixtures

Uncoated, Broad Fluorescent, and Size-Homogeneous CdSe Quantum Dots for Bioanalyses

Zhivko Zhelev、Rumiana Bakalova、Hideki Ohba 等 6 位作者2005-11-25Analytical Chemistry

In the present study, we describe the synthesis of highly luminescent uncoated water-soluble CdSe quantum dots (QDs) possessing the following characteristics: approximately 2 nm in diameter, with very good size distribution (in 95% homodispersed) accompanied by a broad-band photoluminescent spectrum. The synthetic pro…

Advanced biosensing and bioanalysis techniquesQuantum Dots Synthesis And PropertiesNanocluster Synthesis and Applications

Cellulose-Directed Growth of Selenium Nanobelts in Solution

Qingyi Lu、Feng Gao、Sridhar Komarneni2005-11-25Chemistry of Materials

Elemental selenium nanobelts have been synthesized for the first time by a novel and mild solution method. The synthetic reaction was carried out with cellulose as both reducing and morphology-directing agents in solution under simple hydrothermal conditions at low temperature, which is quite different from the therma…

Quantum Dots Synthesis And PropertiesSelenium in Biological SystemsCarbon and Quantum Dots Applications

Synthesis and Photophysical Properties of Annulated Dinuclear and Trinuclear Phthalocyanines

Sergey G. Makarov、Christian Litwinski、Eugeny Ermilov 等 6 位作者2005-11-25Chemistry - A European Journal

Metal-free mononuclear, dinuclear and trinuclear phthalocyanines were prepared by a mixed cyclotetramerisation of a 1,2,4,5-tetracyanobenzene derivative and 4,5-bis(2,6-dimethylphenoxy)phthalonitrile. For the first time, a pi-electron-conjugated trinuclear phthalocyanine was synthesised with phthalocyanine units conne…

Photosynthetic Processes and MechanismsPorphyrin and Phthalocyanine ChemistrySurface Chemistry and Catalysis

Preparation of Doublet, Triangular, and Tetrahedral Colloidal Clusters by Controlled Emulsification

Djamal Zerrouki、Benjamin Rotenberg、Sébastien Abramson 等 8 位作者2005-11-25Langmuir

We describe a six-step method for making colloidal clusters of 2, 3, or 4 silica particles with a radius of 1.2 microm. This method, originally described by Manoharan et al. (Manoharan, V. N.; Elsesser, M. T.; Pine, D. J. Science 2003, 301, 483), is based on the encapsulation of silica spheres in emulsion droplets. Th…

Photonic Crystals and ApplicationsMesoporous Materials and CatalysisPickering emulsions and particle stabilization

Bioinspired colloidal systems vialayer-by-layer assembly

Alexandra S. Angelatos、Kiyofumi Katagiri、Frank Caruso2005-11-25Soft Matter

This paper provides an overview of our recent work in the area of bioinspired colloidal particles. We highlight how modifying the basic polyelectrolyte multilayer shell with materials such as light-absorbing gold nanoparticles, lipid bilayer membranes, and targeting ligands can functionalize colloids prepared the laye…

Nanoparticle-Based Drug DeliveryGold and Silver Nanoparticles Synthesis and ApplicationsPolymer Surface Interaction Studies

The limitations of Slater's element-dependent exchange functional from analytic density functional theory

Rajendra R. Zope、Brett I. Dunlap2005-11-25arXiv

Our recent formulation of the analytic and variational Slater-Roothaan (SR) method, which uses Gaussian basis sets to variationally express the molecular orbitals, electron density and the one body effective potential of density functional theory, is reviewed. Variational fitting can be extended to the resolution of i…

Materials Sciencecond-mat.otherChemical Physics

Design of High Coordination Number Metallomesogens by Decoupling of the Complex-Forming and Mesogenic Groups: Nematic and Lamello-Columnar Mesophases

Thomas Cardinaels、Kris Driesen、Tatjana N. Parac‐Vogt 等 8 位作者2005-11-25Chemistry of Materials

Liquid-crystalline complexes of rhenium(I), yttrium(III), lanthanum(III), neodymium(III), samarium(III), europium(III), erbium(III), and ytterbium(III) were obtained by coupling mesogenic 4-cyanobiphenyl groups via a long alkyl spacer to a substituted imidazo[4,5-f]-1,10-phenanthroline, which acts as the coordinating…

Supramolecular Chemistry and ComplexesMagnetism in coordination complexesLanthanide and Transition Metal Complexes

Electronically interacting single wall carbon nanotube–porphyrin nanohybrids

Gul Rahman、Dirk M. Guldi、Stéphane Campidelli 等 4 位作者2005-11-25Journal of Materials Chemistry

Electronically interacting single wall carbon nanotube–porphyrin nanohybrids were confirmed by microscopic and spectroscopic means to exhibit charge transfer features.

Carbon Nanotubes in CompositesGraphene research and applicationsElectrochemical Analysis and Applications

Evidence of Water-related Discrete Trap State Formation in Pentacene Single Crystal Field-Effect Transistors

C. Goldmann、D. J. Gundlach、B. Batlogg2005-11-25arXiv

We report on the generation of a discrete trap state during negative gate bias stress in pentacene single crystal "flip-crystal" field-effect transistors with a SiO2 gate dielectric. Trap densities of up to 2*10^12 cm^-2 were created in the experiments. Trap formation and trap relaxation are distinctly different above…

Materials ScienceSoft Condensed Matter

Hollow Silica Spheres with an Ordered Pore Structure and Their Application in Controlled Release Studies

Nicole E. Papen‐Botterhuis、Qianyao Sun、Pieter C. M. M. Magusin 等 5 位作者2005-11-25Chemistry - A European Journal

Herein we report the synthesis and characterization of hollow silica spheres with a narrow size distribution, uniform wall thickness, and a worm-like pore structure. The formation of these spheres was monitored by confocal laser scanning microscopy and dynamic light scattering. A model for the molecular build-up of th…

Zeolite Catalysis and SynthesisMesoporous Materials and CatalysisDiatoms and Algae Research

A Novel Silicon Nanotips Antireflection Surface for the Micro Sun Sensor

Choonsup Lee、Sam Y. Bae、Sohrab Mobasser 等 4 位作者2005-11-25Nano Letters

We have developed a new technique to fabricate an antireflection surface using silicon nanotips for use on a micro Sun sensor for Mars rovers. We have achieved randomly distributed nanotips of radii spanning from 20 to 100 nm and aspect ratio of approximately 200 using a two-step dry etching process. The 30 degrees sp…

Photonic and Optical DevicesNanowire Synthesis and ApplicationsOptical Coatings and Gratings

Model for a Macroscopically Disordered Conductor with an Exactly Linear High-Field Magnetoresistance

Vishwesha Guttal、David Stroud2005-11-25arXiv

We calculate the effective resistivity of a macroscopically disordered two dimensional conductor consisting of two components in a perpendicular magnetic field. When two components have equal area fractions, we use a duality theorem to show that the magnetoresistance is non-saturating and at high fields varies exactly…

cond-mat.dis-nnMaterials Science

Application of MCD Spectroscopy and TD−DFT to a Highly Non-Planar Porphyrinoid Ring System. New Insights on Red−Shifted Porphyrinoid Spectral Bands

John Mack、Yoshiaki Asano、Nagao Kobayashi 等 4 位作者2005-11-25Journal of the American Chemical Society

The first magnetic circular dichroism (MCD) spectra are reported for tetraphenyltetraacenaphthoporphyrin (TPTANP). The impact on the electronic structure of steric interactions between the fused acenaphthalene rings and the meso-tetraphenyl substituents is explored based on an analysis of the optical spectra of the Zn…

Photosynthetic Processes and MechanismsPorphyrin and Phthalocyanine ChemistryMetal-Catalyzed Oxygenation Mechanisms

A simplified method for the computation of correlation effects on the band structure of semiconductors

Uwe Birkenheuer、Peter Fulde、Hermann Stoll2005-11-25arXiv

We present a simplified computational scheme in order to calculate the effects of electron correlations on the energy bands of diamond and silicon. By adopting a quasiparticle picture we compute first the relaxation and polarization effects around an electron set into a conduction band Wannier orbital. This is done by…

Materials Science

Decoupled magnetic and electrical switching in manganite trilayer

L. E Hueso、L. Granja、P. Levy 等 4 位作者2005-11-25arXiv

We report magnetic and electrical transport studies of an epitaxially grown trilayer thin film structure comprising La0.59Ca0.41MnO3 sandwiched between La0.67Ca0.33MnO3 electrodes. Since La0.59Ca0.41MnO3 lies at the edge of the thin film ferromagnetic metallic phase field, phase separation effects are expected. These…

Materials Science

The isotropic material closest to a given anisotropic material

Andrew N. Norris2005-11-25arXiv

The isotropic elastic moduli closest to a given anisotropic elasticity tensor are defined using three definitions of elastic distance, the standard Frobenius (Euclidean) norm, the Riemannian distance for tensors, and the log-Euclidean norm. The closest moduli are unique for the Riemannian and the log-Euclidean norms,…

Materials Science

Correlated particle dynamics in concentrated quasi-two-dimensional suspensions

Haim Diamant、Bianxiao Cui、Binhua Lin 等 4 位作者2005-11-25Journal of Physics Condensed Matter

We investigate theoretically and experimentally how the hydrodynamically correlated lateral motion of particles in a suspension confined between two surfaces is affected by the suspension concentration. Despite the long range of the correlations (decaying as 1/ r 2 with the inter-particle distance r ), the concentrati…

Material Dynamics and PropertiesGranular flow and fluidized bedsElectrostatics and Colloid Interactions