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Theoretical Studies of the Mechanism for the Synthesis of Silsesquioxanes. 1. Hydrolysis and Initial Condensation

Takako Kudo、Mark S. Gordon1998-10-22Journal of the American Chemical Society

The mechanisms for the hydrolysis of SiHCl 3 to form HSi(OH) 3 and the condensations of SiH 3 OH and HSi(OH) 3 are studied by using ab initio electronic structure methods including electron correlation via second and fourth order perturbation theory and coupled cluster calculations. In the gas phase, the barrier heigh…

Metal and Thin Film MechanicsSilicone and Siloxane ChemistryMuon and positron interactions and applications

Calculation of macroscopic first-, second-, and third-order optical susceptibilities for the urea crystal

Heribert Reis、Μάνθος Γ. Παπαδόπουλος、R. W. Munn1998-10-22The Journal of Chemical Physics

Macroscopic first-, second-, and third-order susceptibilities of the urea crystal are calculated using static and frequency-dependent ab initio molecular (hyper)polarizabilities at the self-consistent field (SCF) and second-order-Mo/ller–Plesset (MP2) levels. Environmental effects are taken into account using a rigoro…

Nonlinear Optical Materials ResearchSpectroscopy and Quantum Chemical StudiesSolid-state spectroscopy and crystallography

Influence of the Chitosan Surface Profile on the Nucleation and Growth of Calcium Carbonate Films

Sukun Zhang、Kenneth E. Gonsalves1998-10-22Langmuir

Calcium carbonate crystal growth on a chitosan substrate was achieved using a supersaturated calcium carbonate solution. Heterogeneous nucleation of the calcium carbonate crystals was significantly influenced by the chitosan surface profile. Poly(acrylic acid) (MW = 2000, PAA2K) was chosen to modify chitosan surfaces…

Polymer Surface Interaction StudiesCalcium Carbonate Crystallization and InhibitionMaterials Engineering and Processing

X-ray excited optical luminescence (XEOL) detection of x-ray absorption fine structure (XAFS)

L. Soderholm、G. K. Liu、Mark R. Antonio 等 4 位作者1998-10-22The Journal of Chemical Physics

The x-ray excited optical luminescence (XEOL) from a variety of rare-earth ions was used as a detection mode for the collection of L-edge x-ray absorption fine-structure (XAFS) data. In order to understand the source of the observed optical signal, advantage is taken of the known luminescent response of f ions in a va…

Luminescence Properties of Advanced MaterialsLanthanide and Transition Metal ComplexesX-ray Spectroscopy and Fluorescence Analysis

Biotin Reagents for Antibody Pretargeting. 3. Synthesis, Radioiodination, and Evaluation of Biotinylated Starburst Dendrimers

D. Scott Wilbur、Pradip M. Pathare、Donald K. Hamlin 等 5 位作者1998-10-22Bioconjugate Chemistry

We are investigating the hypothesis that biotin multimers can be used with streptavidin and monoclonal antibody conjugates in cancer pretargeting protocols to provide a method of increasing the amount of radioactivity bound on cancer cells in patients. As part of that investigation, a series of biotinylated Starburst…

Click Chemistry and ApplicationsDendrimers and Hyperbranched PolymersProtein Degradation and Inhibitors

Ferroelectricity in Water Ice

Martin J. Iedema、M. J. Dresser、D. L. Doering 等 7 位作者1998-10-22The Journal of Physical Chemistry B

Partially proton-ordered ice I (cubic) was grown from the vapor phase, from 40 to nearly 150 K. It is believed to be metastable and oriented by the asymmetry of the solid−vacuum interface during growth. This was studied using a Kelvin (work function) probe for ice grown on a single-crystal Pt(111) substrate. The ice g…

Surface Modification and SuperhydrophobicityAdvanced Sensor and Energy Harvesting MaterialsMaterial Dynamics and Properties

Synthesis and Magnetization of New Room-Temperature Molecule-Based Magnets: Effect of Stoichiometry on Local Magnetic Structure by X-ray Magnetic Circular Dichroism

Erik Dujardin、Sylvie Ferlay、X. H. Phan 等 10 位作者1998-10-22Journal of the American Chemical Society

The synthesis and the magnetic properties of two new bimetallic chromium−vanadium ferrimagnets, compounds 1 and 2, are reported. They belong to a set of nonstoichiometric Prussian blue analogues C I y V[Cr III (CN) 6 ] z · n H 2 O (C, alkali cation) with T C varying between 295 and 315 K ( T C = 310 K for 1 and 315 K…

Magnetism in coordination complexesLanthanide and Transition Metal ComplexesOrganic and Molecular Conductors Research

Structure of Human Adenosine Kinase at 1.5 Å Resolution,

Irimpan I. Mathews、Mark D. Erion、S.E. Ealick1998-10-22Biochemistry

Adenosine kinase (AK) is a key enzyme in the regulation of extracellular adenosine and intracellular adenylate levels. Inhibitors of adenosine kinase elevate adenosine to levels that activate nearby adenosine receptors and produce a wide variety of therapeutically beneficial activities. Accordingly, AK is a promising…

Protein Structure and DynamicsAdvanced Electron Microscopy Techniques and ApplicationsEnzyme Structure and Function

Self-Assembled Triply Periodic Minimal Surfaces as moulds for Photonic Band Gap Materials

L. Martin-Moreno、F. J. Garcia-Vidal、A. M. Somoza1998-10-22arXiv

We propose systems with structures defined by self-assembled triply periodic minimal surfaces (STPMS) as candidates for photonic bandgap materials. To support our proposal we have calculated the photonic bands for different STPMS and we have found that, at least, the double diamond and gyroid structures present full p…

Materials Sciencephysics.optics

Quantum computing and single-qubit measurements using the spin filter effect

David P. DiVincenzo1998-10-22arXiv

Many things will have to go right for quantum computation to become a reality in the lab. For any of the presently-proposed approaches involving spin states in solids, an essential requirement is that these spins should be measured at the single-Bohr-magneton level. Fortunately, quantum computing provides a suggestion…

Mesoscale and Nanoscale PhysicsMaterials Sciencequant-ph

A density functional study of clean and hydrogen-covered α-MoO3(010): Electronic structure and surface relaxation

M. Chen、U. V. Waghmare、C. M. Friend 等 4 位作者1998-10-22The Journal of Chemical Physics

We report extensive density functional theory calculations, using pseudopotentials with a plane-wave basis, for the properties of the (010) face of molybdenum trioxide (α-MoO3). The surface is modeled by a one-layer slab. Calculated bond lengths compare favorably with experimental measurements. The bonding of the diff…

Catalytic Processes in Materials ScienceTransition Metal Oxide NanomaterialsCatalysis and Oxidation Reactions

Existence of an omni-directional photonic band gap in one-dimensional periodic dielectric structures

Dmitry N. Chigrin、Andrei V. Lavrinenko1998-10-22arXiv

It is shown that total reflection for all incident angles does not require a two- or three-dimensional photonic crystal. We demonstrate that a one-dimensional photonic crystal can exhibit total omni-directional reflection for any incident wave within some frequency region. The formation of the omni-directional gap is…

Materials ScienceSoft Condensed Matter

In Situ Spectroscopic Investigation of Molecular Structures of Highly Dispersed Vanadium Oxide on Silica under Various Conditions

Xingtao Gao、Simon R. Bare、Bert M. Weckhuysen 等 4 位作者1998-10-22OpenAlex

The molecularly dispersed V 2 O 5 /SiO 2 supported oxides were prepared by the incipient wetness impregnation of 2-propanol solutions of V-isopropoxide. The experimental maximum dispersion of surface vanadium oxide species on SiO 2 was achieved at ∼12 wt % V 2 O 5 (∼2.6 V atoms/nm 2 ). The surface structures of the mo…

Catalytic Processes in Materials ScienceTransition Metal Oxide NanomaterialsCatalysis and Oxidation Reactions

Relation between some secondary relaxations and the α relaxations in glass-forming materials according to the coupling model

K. L. Ngai1998-10-22OpenAlex

Some secondary or β relaxations in glass-forming materials involve molecular motions that bear strong resemblance to the primitive α relaxations of the coupling model, although the two are not identical. For these β relaxations, at the glass transition temperature Tg the relaxation time τβ(Tg) is expected to be shorte…

Material Dynamics and PropertiesGlass properties and applicationsPhotochemistry and Electron Transfer Studies

Surface Characterization of Cu−M (M = Ti, Zr, or Hf) Alloy Powder Catalysts

Árpàd Molnár、I. Bertóti、János Szépvölgyi 等 5 位作者1998-10-21The Journal of Physical Chemistry B

X-ray photoelectron spectroscopy was used for surface characterization of amorphous Cu−M alloy powders (Cu 40 Ti 60, Cu 50 Zr 50, and Cu 65 Hf 35 ) produced by mechanical alloying of the constituents. When used as catalyst in the dehydrogenation of alcohols Cu−Zr and Cu−Hf were found to undergo structural changes resu…

Catalytic Processes in Materials ScienceHydrogen Storage and MaterialsNanomaterials for catalytic reactions

Modelling of thermally stimulated depolarization current peaks obtained by global and thermal cleaning experiments

João F. Mano1998-10-21Journal of Physics D Applied Physics

Thermally stimulated depolarization current thermograms were obtained from modelling experiments on polar systems, assuming that the polarization can be described by a weighted summation of elementary Debye-like processes. The analysed situations were studied both by global and by cleaned experiments and the features…

Material Dynamics and PropertiesSolid-state spectroscopy and crystallographyChemical Thermodynamics and Molecular Structure

All Fuchsian Schottky groups are classical Schottky groups

J. O. Button1998-10-21Geometry and topology monographs

Not all Schottky groups of Mobius transformations are classical Schottky groups. In this paper we show that all Fuchsian Schottky groups are classical Schottky groups, but not necessarily on the same set of generators. AMS Classification 20H10; 30F35, 30F40

Magnetism in coordination complexesInorganic Fluorides and Related Compounds

Self-propagating high-temperature synthesis of lithium-chromium ferrites Li0.5Fe2.5-xCrxO4

Maxim V. Kuznetsov、Quentin A. Pankhurst、Ivan P. Parkin1998-10-21Journal of Physics D Applied Physics

Pure and chromium-substituted lithium ferrites have been made in air by self-propagating high-temperature synthesis (SHS), a combustion process involving the reaction of lithium peroxide, iron oxide, chromium oxide and iron or chromium metal powders. Three series of SHS samples were produced: by SHS only; by SHS follo…

Magnetic Properties and Synthesis of FerritesElectromagnetic wave absorption materialsMagneto-Optical Properties and Applications

Effect of Ligand Deuteration on the Decay of Eu3+(5D0) in Tris(2,2,6,6-tetramethyl-3,5-heptanedionato)europium(III)

Todd C. Schwendemann、P. Stanley May、Mary T. Berry 等 5 位作者1998-10-21The Journal of Physical Chemistry A

Contributions to the first-order rate constant for the decay of the Eu 3+ ( 5 D 0 ) state of tris(2,2,6,6-tetramethyl-3,5-heptanedionato)europium(III), Eu(thd) 3, from radiative and multiphonon mechanisms are evaluated independently by measuring the luminescence decay rates in undeuterated Eu(thd) 3, fully deuterated…

Magnetism in coordination complexesRadioactive element chemistry and processingLanthanide and Transition Metal Complexes

Porphyrins with Exocyclic Rings. 13.1 Synthesis and Spectroscopic Characterization of Highly Modified Porphyrin Chromophores with Fused Acenaphthylene and Benzothiadiazole Rings

Timothy D. Lash、Pushpa Chandrasekar、Augustine T. Osuma 等 5 位作者1998-10-21The Journal of Organic Chemistry

As part of a survey on the influence of fused aromatic rings on the porphyrin chromophore, a series of novel structures with fused acenaphthylene or benzothiadiazole rings have been synthesized. Base-catalyzed condensation of 1-nitroacenaphthylene or 4-nitrobenzothiadiazole with esters of isocyanoacetic acid afforded…

Porphyrin and Phthalocyanine ChemistryPhotodynamic Therapy Research StudiesLuminescence and Fluorescent Materials