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Toroidal Nanoobjects from Rosette Assemblies of Melamine‐Linked Oligo(p‐phenyleneethynylene)s and Cyanurates

Shiki Yagai、Sankarapillai Mahesh、Yoshihiro Kikkawa 等 7 位作者2008-05-21Angewandte Chemie International Edition

Nanodonuts! A hydrogen-bonded cyclic assembly (rosette, left) of a melamine featuring π-conjugated oligo(p-phenyleneethynylene) hierarchically self-organizes with a cyanurate in decane under dilute conditions to form toroidal nanostructures (right) with a diameter of 40 nm.

Luminescence and Fluorescent MaterialsSupramolecular Self-Assembly in MaterialsSynthesis and Properties of Aromatic Compounds

Molecular-orbital-free algorithm for excited states in time-dependent perturbation theory

Melissa J. Lucero、Anders M. N. Niklasson、Sergei Tretiak 等 4 位作者2008-05-21arXiv

A non-linear conjugate gradient optimization scheme is used to obtain excitation energies within the Random Phase Approximation (RPA). The solutions to the RPA eigenvalue equation are located through a variational characterization using a modified Thouless functional, which is based upon an asymmetric Rayleigh quotien…

Materials Science

Aqueous toxicity and food chain transfer of quantum dots™ in freshwater algae andCeriodaphnia dubia

Jennifer L. Bouldin、Taylor Ingle、Anindita Sengupta 等 6 位作者2008-05-21Environmental Toxicology and Chemistry

Innovative research and diagnostic techniques for biological testing have advanced during recent years because of the development of semiconductor nanocrystals. Although these commercially available, fluorescent nanocrystals have a protective organic coating, the inner core contains cadmium and selenium. Because these…

Nanoparticles: synthesis and applicationsElectrochemical Analysis and ApplicationsHeavy metals in environment

Exchange energy dominated by large orbital spin-currents in $δ$-Pu

Francesco Cricchio、fredrik Bultmark、Lars Nordström2008-05-21arXiv

The electronic structure of the anomalous $δ$-phase of Pu is analyzed by a general and exact reformulation of the exchange energy of the $f$-shell. It is found that the dominating contribution to the exchange energy is a polarization of orbital spin-currents that preserves the time reversal symmetry, hence a non-magne…

Strongly Correlated ElectronsMaterials Science

Spin-transfer torque in magnetic tunnel junctions: Scattering theory

Jiang Xiao、Gerrit E. W. Bauer、Arne Brataas2008-05-21arXiv

We study the bias-dependent spin-transfer torque in magnetic tunnel junctions in the Stoner model by scattering theory. We show that the in-plane (Slonczewski type) torque vanishes and subsequently reverses its direction when the bias voltage becomes larger or the barrier wider than material and device-dependent criti…

Materials Science

Coupling efficiency for phase locking of a spin transfer oscillator to a microwave current

B. Georges、J. Grollier、M. Darques 等 8 位作者2008-05-21arXiv

The phase locking behavior of spin transfer nano-oscillators (STNOs) to an external microwave signal is experimentally studied as a function of the STNO intrinsic parameters. We extract the coupling strength from our data using the derived phase dynamics of a forced STNO. The predicted trends on the coupling strength…

Materials Science

Atomistic Origin of Urbach Tails in Amorphous Silicon

Yi Pan、F. Inam、M. Zhang 等 4 位作者2008-05-21Physical Review Letters

Exponential band edges have been observed in a variety of materials, both crystalline and amorphous. In this Letter, we infer the structural origins of these tails in amorphous and defective crystalline Si by direct calculation with current ab initio methods. We find that exponential tails appear in relaxed models of…

Thin-Film Transistor TechnologiesSilicon Nanostructures and PhotoluminescenceNanowire Synthesis and Applications

Charge pumping in magnetic tunnel junctions: Scattering theory

Jiang Xiao、Gerrit E. W. Bauer、Arne Brataas2008-05-21arXiv

We study theoretically the charge transport pumped by magnetization dynamics through epitaxial FIF and FNIF magnetic tunnel junctions (F: Ferromagnet, I: Insulator, N: Normal metal). We predict a small but measurable DC pumping voltage under ferromagnetic resonance conditions for collinear magnetization configurations…

Materials Science

Quantitative Absorption Spectroscopy of a Single Gold Nanorod

Otto L. Muskens、Guillaume Bachelier、Natalia Del Fatti 等 7 位作者2008-05-21The Journal of Physical Chemistry C

The spectrally- and polarization-resolved absorption cross-sections of a single gold nanorod have been investigated using the spatial modulation spectroscopy technique. The ensemble of its optical features, that is, longitudinal and transverse surface plasmon resonances and interband absorption, has been quantitativel…

Nonlinear Optical Materials StudiesPlasmonic and Surface Plasmon ResearchGold and Silver Nanoparticles Synthesis and Applications

Reversible switching in phase-change materials

Wojciech Wełnic、Matthias Wuttig2008-05-21Materials Today

Phase-change materials are successfully employed in optical data storage and are becoming a promising candidate for future electronic storage applications. Despite the increasing technological interest, many fundamental properties of these materials remain poorly understood. However, in the last few years the understa…

Phase-change materials and chalcogenidesChalcogenide Semiconductor Thin FilmsLiquid Crystal Research Advancements

Line creep in paper peeling

Jari Rosti、Juha Koivisto、Paola Traversa 等 6 位作者2008-05-21arXiv

The dynamics of a "peeling front" or an elastic line is studied under creep (constant load) conditions. Our experiments show an exponential dependence of the creep velocity on the inverse force (mass) applied. In particular, the dynamical correlations of the avalanche activity are discussed here. We compare various av…

Materials Sciencecond-mat.stat-mech

Electronic structure of Ga$_{1-x}$Cr$_{x}$N and Si-doping effects studied by photoemission and X-ray absorption spectroscopy

G. S. Song、M. Kobayashi、J. I. Hwang 等 20 位作者2008-05-21arXiv

The electronic structure of the magnetic semiconductor Ga$_{1-x}$Cr$_{x}$N and the effect of Si doping on it have been investigated by photoemission and soft x-ray absorption spectroscopy. We have confirmed that Cr in GaN is predominantly trivalent substituting for Ga, and that Cr 3$d$ states appear within the band ga…

Strongly Correlated ElectronsMaterials Science

Non-equilibrium thermodynamic study of magnetization dynamics in the presence of spin-transfer torque

Kazuhiko Seki、Hiroshi Imamura2008-05-21arXiv

The dynamics of magnetization in the presence of spin-transfer torque was studied. We derived the equation for the motion of magnetization in the presence of a spin current by using the local equilibrium assumption in non-equilibrium thermodynamics. We show that, in the resultant equation, the ratio of the Gilbert dam…

Mesoscale and Nanoscale PhysicsMaterials Science

Room temperature electronic template effect of pre-structured SmSi(111)-8x2 interface yielding self-aligned organic molecules

Younes Makoudi、Eric Duverger、Madjid Arab 等 8 位作者2008-05-21arXiv

This work describes an innovative concept for the development of organized molecular systems thanks to the template effect of the pre-structured semi-conductive SmSi(111) interface. This substrate was selected because Sm deposition in the submonolayer range leads to a 8x2-reconstruction, which is a well-defined one-di…

Materials Science

Hydrogen Storage Properties of Space-Confined NaAlH4 Nanoparticles in Ordered Mesoporous Silica

Shiyou Zheng、Fang Fang、Guangyou Zhou 等 7 位作者2008-05-21Chemistry of Materials

A method that is used by space-confining NaAlH 4 into the as-synthesized ordered mesoporous silica (OMS) is presented in the present work. NaAlH 4 in the pores of OMS is obtained by impregnation and drying techniques. It has been found that the space-confined NaAlH 4 in the pores of OMS shows the lower temperature and…

Hybrid Renewable Energy SystemsHydrogen Storage and MaterialsAmmonia Synthesis and Nitrogen Reduction

Ionic Liquid-Assisted Growth of Single-Crystalline Dendritic Gold Nanostructures with a Three-Fold Symmetry

Yao Qin、Yin Song、Nijuan Sun 等 6 位作者2008-05-21Chemistry of Materials

Hierarchical, three-fold symmetrical, single-crystalline gold dendrites were synthesized by the reaction between a zinc plate and a solution of HAuCl 4 in the ionic liquid [BMIM][PF 6 ]. The unique dendritic gold nanostructures show a three-order hierarchy (i.e., a three-fold symmetrical <111>-oriented trunk, three gr…

Theoretical and Computational PhysicsGold and Silver Nanoparticles Synthesis and ApplicationsIonic liquids properties and applications

Conformationally Restricted Dipyrromethene Boron Difluoride (BODIPY) Dyes: Highly Fluorescent, Multicolored Probes for Cellular Imaging

Qingdong Zheng、Gaixia Xu、Paras N. Prasad2008-05-21Chemistry - A European Journal

Novel fluorescent, conformationally restricted dipyrromethene boron difluoride (BODIPY) dyes have been prepared by introducing a naphthalenyl group at the meso position of the BODIPY core. These BODIPY dyes exhibit increased fluorescence quantum yields compared with dyes that have a meso-position phenyl group with int…

Nonlinear Optical Materials StudiesLuminescence and Fluorescent MaterialsNanoplatforms for cancer theranostics

Stability and Controlled Composition of Hexagonal WO3

Imre Miklós Szilágyi、János Madarász、György Pokol 等 10 位作者2008-05-21Chemistry of Materials

This paper discusses the formation of nanosized hexagonal tungsten oxide (h-WO 3 ) during the annealing of hexagonal ammonium tungsten bronze (HATB), (NH 4 ) 0.33− x WO 3− y . This process was investigated by TG/DTA-MS, XRD, SEM, Raman, XPS, and 1 H-MAS NMR analyses. Through adjusting the temperature and atmosphere of…

Gas Sensing Nanomaterials and SensorsTransition Metal Oxide NanomaterialsConducting polymers and applications

Plasmon‐Resonance‐Enhanced Absorption and Circular Dichroism

Itai Lieberman、Gabriel Shemer、Tcipi Fried 等 5 位作者2008-05-21Angewandte Chemie International Edition

Colloidal Ag nanoparticles coated with L-glutathione attached to bimane chromophores were studied by absorption, circular dichroism (CD), and fluorescence spectroscopies. The absorption and CD spectra were resonantly enhanced by Ag surface plasmons. The wavelength and particle-size dependence of the enhancement indica…

Gold and Silver Nanoparticles Synthesis and ApplicationsProtein Interaction Studies and Fluorescence AnalysisPlasmonic and Surface Plasmon Research

Surface Modification of Natural Fibers Using Bacteria: Depositing Bacterial Cellulose onto Natural Fibers To Create Hierarchical Fiber Reinforced Nanocomposites

Marion Pommet、J. Juntaro、Jerry Y. Y. Heng 等 9 位作者2008-05-21Biomacromolecules

Triggered biodegradable composites made entirely from renewable resources are urgently sought after to improve material recyclability or be able to divert materials from waste streams. Many biobased polymers and natural fibers usually display poor interfacial adhesion when combined in a composite material. Here we pro…

Natural Fiber Reinforced CompositesAdvanced Cellulose Research Studiesbiodegradable polymer synthesis and properties