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Effects of halogenation on the ionized and excited states of free-base and zinc porphyrins

Kiet A. Nguyen、Paul N. Day、Ruth Pachter1999-05-08The Journal of Chemical Physics

Ab initio electronic structure theory has been applied to study the effects of β-halogenation on the structure, ionization potentials (IP), and electronic spectra of free-base (PH2) and zinc porphyrins (ZnP). Electronic and infrared (IR) spectra of β-octahalogenated free-base (β-PX8H2; X=F, Cl, Br) and zinc porphyrins…

Porphyrin and Phthalocyanine ChemistryPhotochemistry and Electron Transfer StudiesFree Radicals and Antioxidants

Pressure-induced phase transition in mixed-valence gold complexes Cs2Au2X6 (X=Cl and Br)

X. J. Liu、Yutaka Moritomo、Arao Nakamura 等 4 位作者1999-05-08The Journal of Chemical Physics

Effects of hydrostatic pressure on Raman spectra have been investigated in mixed-valence (MV) gold complexes Cs2Au2X6 (X=Cl and Br). We have observed pressure-induced deactivation of the Raman-active Au-X stretching modes at various temperatures, indicating a pressure-induced phase transition from the MV state to a si…

Organometallic Complex Synthesis and CatalysisOrganic and Molecular Conductors ResearchInorganic Chemistry and Materials

Crystal Structure of NAD(P)H:Flavin Oxidoreductase from Escherichia coli,

Margareta Ingelman、S. Ramaswamy、Vincent Nivière 等 5 位作者1999-05-08Biochemistry

Flavin reductases use flavins as substrates and are distinct from flavoenzymes which have tightly bound flavins. The reduced flavin can serve to reduce ferric complexes and iron proteins. In Escherichia coli, reactivation of ribonucleotide reductase is achieved by reduced flavins produced by flavin reductase. The crys…

Photosynthetic Processes and MechanismsEnzyme Structure and FunctionAmino Acid Enzymes and Metabolism

Quantitative Structure−Property Relationships for the Estimation of Boiling Point and Flash Point Using a Radial Basis Function Neural Network

John Tetteh、Takahiro Suzuki、Ed Metcalfe 等 4 位作者1999-05-08Journal of Chemical Information and Computer Sciences

Radial basis function (RBF) neural network models for the simultaneous estimation of flash point ( T f ) and boiling point ( T b ) based on 25 molecular functional groups and their first-order molecular connectivity index ( 1 χ) have been developed. The success of the whole modeling process depended on a network optim…

Computational Drug Discovery MethodsThermal and Kinetic AnalysisChemical Thermodynamics and Molecular Structure

NMR study of InP quantum dots: Surface structure and size effects

M. Tomaselli、Jeffery L. Yarger、Marcel P. Bruchez 等 7 位作者1999-05-08The Journal of Chemical Physics

We report the results of P31 NMR measurements on trioctylphosphine oxide (TOPO) passivated InP quantum dots. The spectra show distinct surface-capping sites, implying a manifold of crystal–ligand bonding configurations. Two In 31P surface components are resolved and related to different electronic surroundings. With d…

Quantum Dots Synthesis And PropertiesQuantum and electron transport phenomenaMolecular Junctions and Nanostructures

Charge carrier transport in conjugated polymers

Dirk Hertel、H. Bäßler、Ullrich Scherf 等 4 位作者1999-05-08The Journal of Chemical Physics

The charge carrier mobility in a ladder-type poly(paraphenylene) (MeLPPP) and a phenylamino-substituted poly(phenylenevinylene) (PPV) derivative (PAPPV) has been studied in detail by using the time-of-flight (TOF) method. In most cases, the TOF signals feature characteristics of nondispersive charge transport in terms…

Organic Electronics and PhotovoltaicsConducting polymers and applicationsAnalytical Chemistry and Sensors

Pump Built-in Hamiltonian Method for Pump-Probe Spectroscopy

Jun-ichi Inoue、Akira Shimizu1999-05-08arXiv

We propose a new method of calculating nonlinear optical responses of interacting electronic systems. In this method, the total Hamiltonian (system + system-pump interaction) is transformed into a different form that (apparently) does not have a system-pump interaction. The transformed Hamiltonian, which we call the p…

Materials Science

Transport and Magnetic properties of laser ablated La0.7Ce0.3MnO3 films on LaAlO3: Effect of oxygen pressure, sample thickness and co-doping with Ca

P. Raychaudhuri、S. Mukherjee、A. K. Nigam 等 6 位作者1999-05-08arXiv

La0.7Ce0.3MnO3 is a relatively new addition in the family of colossal magnetoresistive manganites where the cerium ion is believed to be in the Ce4+ state. In this paper we report an extensive study the magnetotransport properties of laser ablated La0.7Ce0.3MnO3 films on LaAlO3 with variation in ambient oxygen pressur…

Materials ScienceStrongly Correlated Electrons

Adsorption of Sulfobetaine Polyampholyte on Silica Surfaces from Aqueous Salt Solutions

Tadaya Kato、Masami Kawaguchi、Akira Takahashi 等 5 位作者1999-05-07Langmuir

Adsorption of poly( N -3-sulfopropyl- N -methacrylooxyethyl- N, N -dimethyl ammonium betaine) (polysulfobetaine abbreviated as PSB), which is a neutral- and zwitterion-type polyampholyte, onto a silica surface from aqueous NaCl solutions was studied by adsorbance measurement and ellipsometry. Adsorbance A increases wi…

Hydrogels: synthesis, properties, applicationsPolymer Surface Interaction StudiesElectrostatics and Colloid Interactions

Interface Charge Density Matching as Driving Force for New Mesostructured Oxovanadium Phosphates with Hexagonal Structure, [CTA]xVOPO4·zH2O

Jamal El Haskouri、Manuel Roca、Saúl Cabrera 等 8 位作者1999-05-07Chemistry of Materials

Hexagonal mesostructured mixed-valence oxovanadium phosphates [CTA] x VOPO 4 · z H 2 O, in short ICMUV-2, have been synthesized through a S + I - cooperative mechanism using cationic surfactant (cetyltrimethylammonium, CTAB) rodlike micelles as a template. On the lines of the hypothesis that the driving force leading…

Mesoporous Materials and CatalysisPolyoxometalates: Synthesis and ApplicationsCatalysis and Oxidation Reactions

Enhanced delivery of carboplatin into brain tumours with intravenous CereportTM (RMP-7): dramatic differences and insight gained from dosing parameters

Dwaine F. Emerich、Pamela Snodgrass、Reginald L. Dean 等 9 位作者1999-05-07British Journal of Cancer

Cereport (RMP-7) is a selective bradykinin B2 receptor agonist which increases the permeability of the 'blood-brain tumour barrier' (BBTB) to increase delivery of chemotherapeutic agents to brain tumours. A series of experiments was performed in an RG2 rodent model of glioma to evaluate and refine intravenous (i.v.) p…

Nanoparticle-Based Drug DeliveryRNA Interference and Gene DeliveryDendrimers and Hyperbranched Polymers

Melting Behavior of Poly(ε-caprolactone)-block-Polybutadiene Copolymers

Shuichi Nojima、Noriyuki Kikuchi、Rohadi Awaludin 等 5 位作者1999-05-07Macromolecules

The melting behavior of poly(ε-caprolactone)- block -polybutadiene (PCL- b -PB) copolymers, crystallized at various temperatures T c from the melt (homogeneous state or microphase-separated state), has been studied by small-angle X-ray scattering with synchrotron radiation (SR−SAXS). The strong SR−SAXS intensity peak…

Polymer crystallization and propertiesPolymer Nanocomposites and Propertiesbiodegradable polymer synthesis and properties

Selective Catalytic Reduction of NO by NH3 over a Bulk Sulfated CuO/γ-Al2O3 Catalyst

Sang Mun Jeong、Soon Hwa Jung、Kyung Seun Yoo 等 4 位作者1999-05-07Industrial & Engineering Chemistry Research

Selective reduction of nitric oxide by ammonia over sulfated CuO/γ-Al 2 O 3 was carried out in a fixed-bed reactor. The optimum temperatures of the fresh and sulfated CuO/γ-Al 2 O 3 in the selective catalytic reduction of NO are found to be 350 and 450 °C, respectively. NO reduction with the sulfated catalyst is somew…

Catalytic Processes in Materials ScienceSpacecraft and Cryogenic TechnologiesFluid dynamics and aerodynamics studies

Electrochemical Growth and Characterization of Polyoxometalate-Containing Monolayers and Multilayers on Alkanethiol Monolayers Self-Assembled on Gold Electrodes

Long Cheng、Landong Li、Jian Gong 等 4 位作者1999-05-07Chemistry of Materials

A general strategy has been developed for fabrication of ultrathin monolayer and multilayer composite films composed of nearly all kinds of polyoxometalates (POMs), including isopolyanions (IPAs), and heteropolyanions (HPAs). It involves stepwise adsorption between the anionic POMs and a cationic polymer on alkanethio…

Conducting polymers and applicationsPolyoxometalates: Synthesis and ApplicationsMarine Biology and Environmental Chemistry

Room-Temperature Deintercalation and Self-Extrusion of Ga from Cr 2 GaN

Michel W. Barsoum、L. Farber1999-05-07Science

Bulk samples of the layered ternary nitride Cr2GaN were observed to extrude filaments of pure elemental gallium at room temperature. This self-extrusion phenomenon is best described as a room-temperature deintercalation of gallium from the basal planes of porous Cr2GaN samples. The extruded filaments are single crysta…

2D Materials and ApplicationsMetal and Thin Film MechanicsMXene and MAX Phase Materials

Renormalized Bosonic Interaction of Excitons

Jun-ichi Inoue、Tobias Brandes、Akira Shimizu1999-05-07arXiv

An effective bosonic Hamiltonian of $1s$ excitons with ``spin'' degrees of freedom in two dimension is obtained through a projection procedure, starting from a conventional electron-hole Hamiltonian ${\cal H}_{eh}$. We first demonstrate that a straightforward transformation of ${\cal H}_{eh}$ into a Hamiltonian of bos…

Materials Science

Enhanced Adsorption of Molecules on Surfaces of Nanocrystalline Particles

Hengzhong Zhang、R. Lee Penn、Robert J. Hamers 等 4 位作者1999-05-07The Journal of Physical Chemistry B

Quantitative measurements of adsorption from solution show up to a 70-fold increase in the adsorption coefficient when a variety of organic acids are adsorbed onto 6 nm compared to 16 nm nanocrystalline titania particles. A Langmuir adsorption model modified to include the dependence of interfacial tension (interfacia…

Quantum Dots Synthesis And PropertiesIron oxide chemistry and applicationsnanoparticles nucleation surface interactions

Enhancement of chemotherapy by manipulation of tumour pH

Natarajan Raghunand、Xi He、Robert van Sluis 等 10 位作者1999-05-07OpenAlex

The extracellular (interstitial) pH (pHe) of solid tumours is significantly more acidic compared to normal tissues. In-vitro, low pH reduces the uptake of weakly basic chemotherapeutic drugs and, hence, reduces their cytotoxicity. This phenomenon has been postulated to contribute to a 'physiological' resistance to wea…

Mass Spectrometry Techniques and ApplicationsLanthanide and Transition Metal ComplexesElectron Spin Resonance Studies

Processible Nanostructured Materials with Electrical Conductivity and Magnetic Susceptibility: Preparation and Properties of Maghemite/Polyaniline Nanocomposite Films

Ben Zhong Tang、Yanhou Geng、Jacky W. Y. Lam 等 9 位作者1999-05-07OpenAlex

We here present a versatile process for the preparation of maghemite/polyaniline (γ-Fe 2 O 3 /PAn) nanocomposite films with macroscopic processibility, electrical conductivity, and magnetic susceptibility. The γ-Fe 2 O 3 nanoparticles are coated and the PAn chains are doped by anionic surfactants of ω -methoxypoly(eth…

Electrochemical sensors and biosensorsConducting polymers and applicationsElectrochemical Analysis and Applications

Novel winding for a gas-insulated transformer

A.F. Atkins、D.W. Auckland、Brian Axcell 等 4 位作者1999-05-06IEE Proceedings - Science Measurement and Technology

There are numerous operational problems with the technology of oil-filled transformers including their considerable mass and associated civil engineering. In addition, blast walls, acoustic baffles or sufficient space are required to protect surrounding buildings in an urban environment. In an attempt to answer these…

High voltage insulation and dielectric phenomenaPower Transformer Diagnostics and InsulationThermal Analysis in Power Transmission