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Synthesis of soluble branched polyimides derived from an ABB′ monomer

Kun‐Li Wang、Mitsutoshi Jikei、Masa‐aki Kakimoto2004-05-20Journal of Polymer Science Part A Polymer Chemistry

Abstract A novel ABB′ monomer, an isomeric mixture of 4‐[4‐(2,4‐diaminophenoxy)phenoxy]phthalic acid 2‐methyl ester, was successfully prepared. The direct polycondensation of the ABB′ monomer was carried out to form polyamic acid monomethyl ester as a precursor with an inherent viscosity of 0.30 dL/g and a number‐aver…

Epoxy Resin Curing ProcessesDendrimers and Hyperbranched PolymersSynthesis and properties of polymers

Molecular Dynamics of Poly(benzylphenyl ether) Dendrimers: Effects of Backfolding on Förster Energy-Transfer Rates

Wilfredo Ortiz、Adrián E. Roitberg、Jeffrey L. Krause2004-05-20The Journal of Physical Chemistry B

We present the results of structural studies of poly(benzylphenyl ether) dendrimers (PBPE dendrimers) using classical molecular dynamics simulations. Specifically, we focus on four generations of PBPE dendrimer at 298 K. Our objectives are to calculate donor/acceptor distances and Förster energy-transfer rates as a fu…

Molecular Junctions and NanostructuresLuminescence and Fluorescent MaterialsDendrimers and Hyperbranched Polymers

Cold electron scattering inSF6andC6F6: Bound and virtual state channels

D. Field、Nykola C. Jones、J. P. Ziesel2004-05-20Physical Review A

Experimental data are presented for the scattering of cold electrons by ${\text{SF}}_{6}$ and ${\mathrm{C}}_{6}{\mathrm{F}}_{6}$, down to energies of a few meV, with an energy resolution varying between 0.95 and $1.5\phantom{\rule{0.3em}{0ex}}\text{meV}$ (full width at half maximum) in the electron beam. The measured…

Semiconductor materials and devicesDiamond and Carbon-based Materials ResearchElectronic and Structural Properties of Oxides

Depletion potential in colloidal mixtures of hard spheres and platelets

Ludger Harnau、S. Dietrich2004-05-20Physical Review E

The depletion potential between two hard spheres in a solvent of thin hard disclike platelets is investigated by using either the Derjaguin approximation or density functional theory. Particular attention is paid to the density dependence of the depletion potential. A second-order virial approximation is applied, whic…

Phase Equilibria and ThermodynamicsMaterial Dynamics and PropertiesSurfactants and Colloidal Systems

Catalytic Performance of [Ti,Al]-Beta in the Alkene Epoxidation Controlled by the Postsynthetic Ion Exchange

Yasuhide Goa、Peng Wu、Takashi Tatsumi2004-05-20The Journal of Physical Chemistry B

Novel methods for enhancing the epoxide selectivity in the alkene epoxidation over [Ti,Al]-Beta have been developed. When as-synthesized [Ti,Al]-Beta was treated with aqueous ammonium nitrate solution and successively calcined at low temperature, a dramatic enhancement of epoxide selectivity was attained in the liquid…

Polyoxometalates: Synthesis and ApplicationsChemical Synthesis and ReactionsChemical Synthesis and Characterization

Capillary Condensation in Liquid-Crystal Colloids

Holger Stark、Jun‐ichi Fukuda、Hiroshi Yokoyama2004-05-20Physical Review Letters

We study capillary condensation between two spherical particles dispersed in the isotropic phase of a nematic liquid crystal. Within the Landau-de Gennes theory, we calculate interaction energies due to the formation of capillary bridges that reproduce experimental observations. Close to the critical point of the tran…

Liquid Crystal Research AdvancementsMaterial Dynamics and PropertiesPlant and animal studies

Manipulation of the Active Site Loops of d-Hydantoinase, a (β/α)8-Barrel Protein, for Modulation of the Substrate Specificity

Young-Hoon Cheon、Hee‐Sung Park、Jin‐Hyun Kim 等 5 位作者2004-05-20Biochemistry

We previously proposed that the stereochemistry gate loops (SGLs) constituting the substrate binding pocket of D-hydantoinase, a (beta/alpha)(8)-barrel enzyme, might be major structural determinants of the substrate specificity [Cheon, Y. H., et al. (2002) Biochemistry 41, 9410-9417]. To construct a mutant D-hydantoin…

Chemical Synthesis and AnalysisEnzyme Structure and FunctionAmino Acid Enzymes and Metabolism

Synthesis, Characterization, and Electrochemical Behavior of Viologen-Functionalized Poly(Amidoamine) Dendrimers

Mi‐Kyung Oh2004-05-20Bulletin of the Korean Chemical Society

Amineterminated, ethylenediamine core polyamidoamine starburst dendrimers of generation 2 (G2), generation 4 (G4) and generation 6 (G6) have been successfully surface-modified via an amide coupling reaction with 4-ethyl, 4'-(3-propionic) bipyridinium cation and the electrochemical behavior of the resulting dendrimers…

Conducting polymers and applicationsMolecular Junctions and NanostructuresDendrimers and Hyperbranched Polymers

Splayed polarization in the ferroelectric phase of a bent-core liquid crystal as studied by optical second-harmonic generation

Fumito Araoka、Hajime Hoshi、Hideo Takezoe2004-05-20Physical Review E

Splayed polarization orientation has been confirmed in the anticlinic ferroelectric phase of a bent-core liquid crystal containing chiral end chains, P-8 -OPIMB6(*), by optical second-harmonic generation (SHG). The in-plane anisotropy of the SHG signal exhibits an unusual six-peak pattern under the rotation of paralle…

Liquid Crystal Research AdvancementsNonlinear Optical Materials ResearchMolecular spectroscopy and chirality

Reinforcement of elastomeric polypropylene by nanoclay fillers

Yen Vu、Guru S. Rajan、James E. Mark 等 4 位作者2004-05-20Polymer International

Abstract Polypropylene (PP) was prepared by metallocene catalysts so as to have a stereoblock structure, with isotactic sequences long enough to give crystallites functioning as crosslinks, but small enough in number to have the atactic chains predominate in a surrounding elastomeric matrix. The resulting thermoplasti…

Polymer crystallization and propertiesPolymer Nanocomposites and PropertiesPolymer Nanocomposite Synthesis and Irradiation

Crystal structure of a novel manganese‐containing cupin (TM1459) from Thermotoga maritima at 1.65 Å resolution

Lukasz Jaroszewski、Robert Schwarzenbacher、F. von Delft 等 47 位作者2004-05-20Proteins Structure Function and Bioinformatics

The TM1459 gene of Thermotoga maritima encodes a conserved hypothetical protein with a molecular weight of 12,977 Da (residues 1–114) and a calculated isoelectric point of 5.6. Currently, no functional annotation has been made for this protein, made fold recognition methods such as Fold and Function Assignment System…

Genomics and Phylogenetic StudiesProtein Structure and DynamicsEnzyme Structure and Function

Modification of carbohydrate polymers via grafting of methacrylonitrile onto pregelled starch using potassium monopersulfate/Fe2+ redox pair

KhM Mostafa、Mostafa Morsy2004-05-20Polymer International

Abstract The graft copolymerization of reactive pregelled starch (PGS) with methacrylonitrile (MAN) was performed and the reaction conditions were optimized using potassium monopersulfate (PMPS) in the presence of ferrous ion redox pair as initiator. Emphasis was directed towards increasing the graft formation and dec…

Nanocomposite Films for Food Packagingbiodegradable polymer synthesis and propertiesElectrospun Nanofibers in Biomedical Applications

Pegylated polystyrene particles as a model system for artificial cells

Fenghua Meng、G.H.M. Engbers、Andrea Gessner 等 5 位作者2004-05-20Journal of Biomedical Materials Research Part A

Pegylated polystyrene particles (PS-PEG) were prepared as a model system for artificial cells, by modification of carboxyl polystyrene particles (PS-COOH) with homo- and hetero-bifunctional polyethylene glycols (PEG, MW 1500, 3400, and 5000) containing an amino end group for immobilization and an amino, hydroxyl, or m…

Polymer Surface Interaction Studies3D Printing in Biomedical ResearchBlood properties and coagulation

Preparation and properties of styrene–ethylene/butylene–styrene (SEBS)–clay hybrids

Young‐Wook Chang、Jae‐Yong Shin、Sung Hun Ryu2004-05-20Polymer International

Abstract Styrene–ethylene/butylene–styrene triblock copolymer (SEBS)–clay hybrids were prepared by melt blending SEBS and organoclay using an internal mixer. Maleic anhydride modified SEBS (SEBS–MA) was used as a compatibilizer. X‐ray diffraction and transmission electron microscopy revealed that silicate layers of th…

Concrete and Cement Materials ResearchPolymer Nanocomposites and PropertiesPolymer Nanocomposite Synthesis and Irradiation

pH-Controlled Swelling of Polyelectrolyte Multilayer Microcapsules

Byoung‐Suhk Kim、Olga I. Vinogradova2004-05-20The Journal of Physical Chemistry B

We explore quantitatively the effect of pH on the osmotically induced swelling of polyelectrolyte multilayer microcapsules filled with solutions of a strong polyanion. The shells of the microcapsules are composed of strong polyanions and weak polycations via a layer-by-layer electrostatic self-assembly. The equilibriu…

Surface Modification and SuperhydrophobicityPolymer Surface Interaction StudiesDendrimers and Hyperbranched Polymers

Reorganization and Melting of Polyethylene Single Crystals: Complementary TEM, DSC, and Real-Time AFM Studies

S. J. Organ、Jamie K. Hobbs、M. J. Miles2004-05-20Macromolecules

The reorganization and melting of single crystals of linear polyethylene with lozenge and truncated-lozenge habits has been studied in situ during slow continuous heating using atomic force microscopy. The morphological insights obtained are backed up by complementary experiments using transmission electron microscopy…

Polymer crystallization and propertiesPolymer Nanocomposites and PropertiesMicroplastics and Plastic Pollution

Status of EUV micro-exposure capabilities at the ALS using the 0.3-NA MET optic

Patrick Naulleau、Kenneth A. Goldberg、Erik H. Anderson 等 24 位作者2004-05-20Proceedings of SPIE, the International Society for Optical Engineering/Proceedings of SPIE

The success of recent static printing experiments at Lawrence Berkeley National Laboratory’s Advanced Light Source (ALS) using the EUV LLC Engineering Test Stand (ETS) Set-2 optic has demonstrated the utility of synchrotron-based EUV exposure stations. Although not viable light sources for commercial lithography, sync…

X-ray Spectroscopy and Fluorescence AnalysisElectron and X-Ray Spectroscopy TechniquesPhotocathodes and Microchannel Plates

Electronic Spectra and Configuration Interaction of Tm3+ in TmCl63-

Michèle D. Faucher、Peter A. Tanner、Chris S. K. Mak2004-05-20The Journal of Physical Chemistry A

Low-temperature electronic absorption and emission data are reported for Tm 3+ at the octahedral site in crystals of Cs 2 NaTmCl 6 . Thirty-seven crystal field levels (total degeneracy 88) of the f 12 configuration (total degeneracy 91) have been assigned, and in several cases the levels are split due to electron−phon…

Luminescence Properties of Advanced MaterialsLanthanide and Transition Metal ComplexesSolid-state spectroscopy and crystallography

Effectiveness of antioxidant‐impregnated film in retarding lipid oxidation

Youn Suk Lee、Han‐Seung Shin、Jong‐Koo Han 等 5 位作者2004-05-20Journal of the Science of Food and Agriculture

Abstract The effectiveness of an antioxidant‐impregnated film to retard autoxidation of a packaged model product containing linoleic acid, via an evaporation/sorption mechanism, was evaluated as a function of storage time and temperature. The rate of loss of antioxidant from the package film structure was described by…

Postharvest Quality and Shelf Life ManagementNanocomposite Films for Food Packaging

Synthesis of Gold Nanoparticles from an Organometallic Compound in Supercritical Carbon Dioxide

Kunio Esumi、Susumu Sarashina、Tomokazu Yoshimura2004-05-20Langmuir

This article presents the synthesis of gold nanoparticles in a single-phase supercritical fluid carbon dioxide solvent. The gold nanoparticles were formed by the reduction of triphenylphosphine gold(I) perfluorooctanoate with dimethylamineborane. Transmission electron microscopy, X-ray photoelectron spectroscopy, and…

Gold and Silver Nanoparticles Synthesis and ApplicationsCatalytic Processes in Materials SciencePhase Equilibria and Thermodynamics