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Layered Double Hydroxides with Intercalated Porphyrins as Photofunctional Materials: Subtle Structural Changes Modify Singlet Oxygen Production

Kamil Lang、Petr Bezdička、J.L. Bourdelande 等 10 位作者2007-06-27Chemistry of Materials

This study presents new photofunctional materials producing singlet oxygen, 1 O 2, and investigates the interdependence between their structural and photophysical properties. These materials consist of Mg−Al layered double hydroxides (LDH) with intercalated photosensitizers, 5,10,15,20-tetrakis(4-sulfonatophenyl)porph…

Porphyrin and Phthalocyanine ChemistryAdvanced Photocatalysis TechniquesLayered Double Hydroxides Synthesis and Applications

Chemical modification of chitosan: synthesis and biological activity of new heterocyclic chitosan derivatives

Mohamed E. I. Badawy2007-06-27Polymer International

Abstract BACKGROUND: Numerous works have been published on the chemical modification of chitosan; this polymer is still being modified, leading to various derivatives with improved properties. In the present study, heterocyclic aldehydes including furan‐2‐carbaldehyde, 5‐methylfuran‐2‐carbaldehyde, 3‐pyridine carboxya…

Nanocomposite Films for Food PackagingPineapple and bromelain studies

Dendrimer Effects on Peptide and Protein Fibrillation

Peter M. H. Heegaard、Ulrik Boas、Daniel E. Otzen2007-06-27Macromolecular Bioscience

Dendrimers are synthetic, symmetrically branched polymers that can be manufactured to a high degree of definition and therefore present themselves as monodisperse entities. Flexible and globular in shape and compartementalized into a partly inaccessible interior and a highly exposed surface, they offer numerous possib…

RNA Interference and Gene DeliveryDendrimers and Hyperbranched PolymersChemical Synthesis and Analysis

Bioactive Cardenolides from the Stems and Twigs of Nerium oleander

Ming Zhao、Liming Bai、Liyan Wang 等 20 位作者2007-06-27Journal of Natural Products

Four new cardenolide monoglycosides, cardenolides N-1 (1), N-2 (2), N-3 (3), and N-4 (4), were isolated from Nerium oleander, together with two known cardenolides, 5 and 12, and seven cardenolide monoglycosides, 6-11 and 13. The structures of compounds 1-4 were established on the basis of their spectroscopic data. The…

Phytochemistry and Bioactive CompoundsSesquiterpenes and Asteraceae StudiesPhytochemical Studies and Bioactivities

Hard-Sphere Packing and Icosahedral Assembly in the Formation of Mesoporous Materials

Jiawei Tang、Xufeng Zhou、Dongyuan Zhao 等 6 位作者2007-06-27Journal of the American Chemical Society

We report the synthesis and characterization of a novel mesoporous material with a face-centered cubic (fcc) symmetry and intrinsic bimodal pores. Moreover, an icosahedral (ICO) mesostructure with both meso- and macroscale 5-fold symmetry is observed. We propose a hard-sphere packing (HSP) mechanism for the formation…

Aerogels and thermal insulationPolyoxometalates: Synthesis and ApplicationsMesoporous Materials and Catalysis

Mathematical Modelling of Proton‐Conducting Solid Oxide Fuel Cells and Comparison with Oxygen‐Ion‐Conducting Counterpart

Meng Ni、Michael K.H. Leung、Dennis Y.C. Leung2007-06-27Fuel Cells

Abstract Proton‐conducting solid oxide fuel cells (H‐SOFC), using a proton‐conducting electrolyte, potentially have higher maximum energy efficiency than conventional oxygen‐ion‐conducting solid oxide fuel cells (O‐SOFC). It is important to theoretically study the current–voltage ( J – V ) characteristics in detail in…

Catalysis and Oxidation ReactionsChemical Looping and Thermochemical ProcessesAdvancements in Solid Oxide Fuel Cells

Low-Temperature Crystallization of Eu-Doped Red-Emitting CaAlSiN3 from Alloy-Derived Ammonometallates

Jinwang Li、Tomoaki Watanabe、Hiroshi Wada 等 5 位作者2007-06-27Chemistry of Materials

A solution route toward multinary nitrides was demonstrated in the synthesis of Eu-doped CaAlSiN3. During a metal−ammonometallate−nitride conversion in the ammonia system, the nitride crystallized into red-emitting nanocrystals at temperatures up to only 800 °C, i.e., 1000 °C lower than the previous method.

Advanced ceramic materials synthesisMXene and MAX Phase MaterialsInorganic Chemistry and Materials

Phase Transition at a Nanometer Scale Detected by Acoustic Emission within the Cubic PhasePb(Zn1/3Nb2/3)O3−xPbTiO3Relaxor Ferroelectrics

Michael Roth、E. Mojaev、E. Dul’kin 等 5 位作者2007-06-27Physical Review Letters

Pb(Zn(1/3)Nb(2/3))O3-xPbTiO(3) (x=4.5%-12%) relaxor ferroelectric crystals have been studied by means of acoustic emission (AE) in the 400-540 K temperature range. An anomalous AE activity independent of the ground state relaxor/morphotropic/ferroelectric crossover has been revealed at around 500 K, and it is associat…

Ferroelectric and Piezoelectric MaterialsMultiferroics and related materialsPhotorefractive and Nonlinear Optics

Time-dependent picture of the charge-transfer contributions to surface enhanced Raman spectroscopy

John R. Lombardi、Ronald L. Birke2007-06-27The Journal of Chemical Physics

We reexamine the Herzberg-Teller theory of charge-transfer contributions to the theory of surface enhanced Raman scattering (SERS). In previous work, the Kramers-Heisenberg-Dirac framework was utilized to explain many of the observed features in SERS. However, recent experimental and theoretical developments suggest t…

Electrochemical Analysis and ApplicationsQuantum Dots Synthesis And PropertiesGold and Silver Nanoparticles Synthesis and Applications

Preparation and characterization of nylon‐6/PPy/MMT composite of nanocomposite

Seyed Jamaleddin Peighambardoust、Behzad Pourabbas2007-06-27Journal of Applied Polymer Science

Abstract Series of composites consisting of polypyrrole/montmorillonite nanocomposites in the matrix of Nylon6 has been synthesized and characterized in this work. The composites were processable, so that test samples were prepared by compression‐molding of the materials for electrical property measurements. Intercala…

Advanced Battery Materials and TechnologiesPolymer Nanocomposites and PropertiesConducting polymers and applications

Phase field modeling of fracture and stress-induced phase transitions

Robert Spatschek、C. Müller-Gugenberger、Efim A. Brener 等 4 位作者2007-06-27Physical Review E

We present a continuum theory to describe elastically induced phase transitions between coherent solid phases. In the limit of vanishing elastic constants in one of the phases, the model can be used to describe fracture on the basis of the late stage of the Asaro-Tiller-Grinfeld instability. Starting from a sharp inte…

Advanced Mathematical Modeling in EngineeringTheoretical and Computational PhysicsSolidification and crystal growth phenomena

Normal zone in $YBa_2Cu_3O_{6+x}$-coated conductors

George A. Levin、Paul N. Barnes2007-06-27arXiv

We consider the distribution of an electric field in YBCO-coated conductors for a situation in which the DC transport current is forced into the copper stabilizer due to a weak link -- a section of the superconducting film with a critical current less than the transport current. The electric field in the metal substra…

Materials ScienceSuperconductivity

Optical 'Shorting Wires'

Andrea Alu、Nader Engheta2007-06-27arXiv

Connecting lumped circuit elements in a conventional circuit is usually accomplished by conducting wires that act as conduits for the conduction currents with negligible potential drops. More challenging, however, is to extend these concepts to optical nanocircuit elements. Here, following our recent development of op…

Materials Science

Distinguishing Bulk-Diffusion from Surface-Desorption Limited Gas Release Processes

Ricardo E. Avila2007-06-27arXiv

The release of a gas limited by surface desorption, or by diffusion from the bulk of spherical pebbles is revisited. A method is proposed to identify the release limiting process, by comparing a partial temperature ramp, up to slightly beyond the release peak, followed by a rapid temperature drop, to a second, full re…

cond-mat.stat-mechcond-mat.otherMaterials Science

Light-induced magnetic precession in (Ga,Mn)As slabs: Hybrid standing-wave Damon-Eshbach modes

D. M. Wang、Yuhang Ren、X. Liu 等 6 位作者2007-06-27Physical Review B

Coherent oscillations associated with spin precessions were observed in ultrafast optical experiments on ferromagnetic (Ga,Mn)As films. Using a complete theoretical description of the processes by which light couples to the magnetization, values for the anisotropy constants and the spin stiffness were unambiguously de…

Magnetic properties of thin filmsMagnetic and transport properties of perovskites and related materialsZnO doping and properties

Alkali Halide Surfaces Near Melting: Wetting and Nanofriction Properties

D. Ceresoli、T. Zykova-Timan、U. Tartaglino 等 4 位作者2007-06-27arXiv

Alkali halide (100) crystal surfaces are poorly wetted by their own melt at the triple point. We carried out simulations for NaCl(100) within the well tested BMHFT model potential. Calculations of the solid-vapor, solid-liquid and liquid-vapor free energies showed that solid NaCl(100) is a non-melting surface, and exp…

cond-mat.stat-mechSoft Condensed MatterMaterials Science

Pseudo-Quantum Criticality in Electron Liquids Exhibited in Expanded Alkali Metals

Hideaki Maebashi、Yasutami Takada2007-06-27arXiv

With paying special attention to the divergence in the compressibility $κ$, we study the Coulombic screening in alkali metals to find singular long-range fluctuations in the electronic polarization originating from this divergence. As a consequence of this singularity, we predict the decrease of the equilibration dist…

cond-mat.otherMaterials Science

Molecular dynamics simulations of the dipolar-induced formation of magnetic nanochains and nanorings

A. Hucht、S. Buschmann、P. Entel2007-06-27arXiv

Iron, cobalt and nickel nanoparticles, grown in the gas phase, are known to arrange in chains and bracelet-like rings due to the long-range dipolar interaction between the ferromagnetic (or super-paramagnetic) particles. We investigate the dynamics and thermodynamics of such magnetic dipolar nanoparticles for low dens…

cond-mat.stat-mechMaterials Science

Unambiguous symmetry assignment for the top valence band of ZnO by magneto-optical studies of the free A-exciton state

Lu Ding、Chunlei Yang、Hongtao He 等 8 位作者2007-06-27arXiv

We studied the circular polarization and angular dependences of the magneto-photoluminescence spectra of the free A-exciton 1S state in wurtzite ZnO at T = 5 K. The circular polarization properties of the spectra clearly indicate that the top valence band has Gamma_7 symmetry. The out-of-plane component of the magneti…

Materials Science