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Structure–property relationships of poly(urethane urea)s with ultra‐low monol content poly(propylene glycol) soft segments. I. Influence of soft segment molecular weight and hard segment content

Matthew J. O’Sickey、Bruce D. Lawrey、Garth L. Wilkes2002-01-30Journal of Applied Polymer Science

Abstract Structure–property relationships in poly(urethane urea)s synthesized with ultra‐low monol content poly(propylene glycol) soft segments were investigated as soft segment molecular weight (2000, 4000, and 8000 g/mol) and hard segment content (6.3 and 9.0 wt %) were varied. Morphological features such as interdo…

Polymer crystallization and propertiesPolymer composites and self-healingEpoxy Resin Curing Processes

Chemistry Inside Carbon Nanotubes: the Menshutkin SN2 Reaction

Mathew D. Halls、H. Bernhard Schlegel2002-01-30The Journal of Physical Chemistry B

In an effort to gain insight into the effect of carbon nanotube confinement on reaction enthalpies and activation energies, calculations using hybrid density functional theory have been carried out for the Menshutkin S N 2 reaction in gas phase and inside carbon nanotubes. The polarizability of the carbon nanotubes pr…

Carbon Nanotubes in CompositesGraphene research and applicationsFullerene Chemistry and Applications

Classification of one-dimensional quasilattices into mutual local-derivability classes

Komajiro Niizeki、Nobuhisa Fujita2002-01-30arXiv

One-dimensional quasilattices are classified into mutual local-derivability (MLD) classes on the basis of geometrical and number-theoretical considerations. Most quasilattices are ternary, and there exist an infinite number of MLD classes. Every MLD class has a finite number of quasilattices with inflation symmetries.…

Materials Science

Soft Chemistry Routes to YPO4-Based Phosphors: Dependence of Textural and Optical Properties on Synthesis Pathways

Jean‐Marie Nédélec、Daniel Avignant、R. Mahiou2002-01-30Chemistry of Materials

Different liquid routes have been used to prepare Eu 3+ -activated YPO 4 phosphors. These materials have been compared with conventionally obtained YPO 4 . For the first time (to our knowledge), a specific sol−gel approach has been developed to produce this material. All phases have been checked with X-ray diffraction…

Luminescence Properties of Advanced MaterialsPerovskite Materials and ApplicationsLanthanide and Transition Metal Complexes

Density-functional study of water adsorption on thePuO2(110)surface

Xueyuan Wu、Asok Ray2002-01-30Physical review. B, Condensed matter

Water adsorption on a ${\mathrm{PuO}}_{2}(110)$ surface is studied using a periodic model with both the local-density approximation (LDA) and the generalized gradient approximation (GGA) of density-functional theory. The 60 core electrons of the Pu atom are represented by a relativistic effective core potential, and s…

Advanced Chemical Physics StudiesHydrogen Storage and MaterialsNuclear Materials and Properties

Dislocation Emission around Nanoindentations on a (001) fcc Metal Surface Studied by STM and Atomistic Simulations

O. Rodriguez de la Fuente、J. A. Zimmerman、M. A. Gonzalez 等 7 位作者2002-01-30arXiv

We present a combined study by Scanning Tunneling Microscopy and atomistic simulations of the emission of dissociated dislocation loops by nanoindentation on a (001) fcc surface. The latter consist of two stacking-fault ribbons bounded by Shockley partials and a stair-rod dislocation. These dissociated loops, which in…

Materials Science

Infrared Hole-Burning of Crystalline Ammonium Copper Tutton Salt: Tunneling Kinetics and Jahn−Teller Distortions

Yun-Hwan Cha、Herbert L. Strauss2002-01-29The Journal of Physical Chemistry A

Irradiation of the N−D stretching band in crystalline deuterium-doped ammonium copper Tutton salt rotates the ammonium ion and changes the conformation of molecules about the copper. The crystal salt exists in at least two different crystal forms, each form containing a particular Jahn−Teller distorted copper conforma…

Nonlinear Optical Materials ResearchSolid-state spectroscopy and crystallographyInorganic Chemistry and Materials

Adsorption and Pressure Swing Desorption of NOx in Na−Y Zeolite: Experiments and Modeling

Jean-François Brilhac、Ayesha Sultana、P. Gilot 等 4 位作者2002-01-29Environmental Science & Technology

Pressure swing NOx adsorption-desorption cycles were performed in the temperature range 200-350 degrees C using a fixed adsorbent bed of compressed Na-Y pellets and using a honeycomb coated with Na-Y powder. The experiments were performed using a synthetic gas mixture mimicking exhaust from a lean burn internal combus…

Catalytic Processes in Materials ScienceCatalysis and Oxidation ReactionsIndustrial Gas Emission Control

Correlation between crystallization kinetics and microdomain morphology in block copolymer blends exhibiting confined crystallization

Wen‐Chuan Lee、Hsin‐Lung Chen、Tsang‐Lang Lin2002-01-29Journal of Polymer Science Part B Polymer Physics

Abstract The crystallization kinetics of poly(ethylene oxide) (PEO) blocks in poly(ethylene oxide)‐ block ‐poly(1,4‐butadiene) (PEO‐ b ‐PB)/poly(1,4‐butadiene) (PB) blends were previously found to display a one‐to‐one correlation with the microdomain morphology. The distinct correlation was postulated to stem from the…

Polymer crystallization and propertiesAdvanced Polymer Synthesis and CharacterizationBlock Copolymer Self-Assembly

Evidence that gold(iii) porphyrins are not electrochemically inert: facile generation of gold(ii) 5,10,15,20-tetrakis(3,5-di-tert-butylphenyl)porphyrin

Karl M. Kadish、E Wenbo、Zhongping Ou 等 8 位作者2002-01-29Chemical Communications

Gold(III) porphyrin 1 is shown to undergo reduction at the central metal ion to give the first known gold(II) porphyrin overturning the long held assumption that reduction of such complexes only occurs at the macrocycle.

Molecular Sensors and Ion DetectionPorphyrin and Phthalocyanine ChemistryElectrochemical Analysis and Applications

Continuous-Wave and Time-Resolved Optically Detected Magnetic Resonance Studies of Nonetched/Etched InP Nanocrystals

L. Langof、E. Ehrenfreund、Efrat Lifshitz 等 5 位作者2002-01-29The Journal of Physical Chemistry B

The low temperature photoluminescence spectrum of InP nanocrystals (NCs) is composed of a near band-edge exciton and a defect emission band at lower energies. The present study characterized the defect emission utilizing an optically detected magnetic resonance spectroscopy (ODMR) both in continuous-wave and time-reso…

Semiconductor Quantum Structures and DevicesQuantum Dots Synthesis And PropertiesChalcogenide Semiconductor Thin Films

C−H⋅⋅⋅O Hydrogen Bond Mediated Chain Reversal in a Peptide Containing a γ-Amino Acid Residue, Determined Directly from Powder X-ray Diffraction Data

Eugene Cheung、Emma E. McCabe、Kenneth D. Harris 等 7 位作者2002-01-29Angewandte Chemie International Edition

Similar to the classical β turn: An intramolecular cyclic 10-atom motif is defined in the molecular conformation of Piv-lPro-γ-Abu-NHMe (see powder X-ray diffraction structure; Piv: pivaloyl, Lpro: L-proline, γ-Abu: γ-aminobutyric acid) by a C−H⋅⋅⋅O interaction. This study emphasizes the considerable potential of powd…

Crystallography and molecular interactionsChemical Synthesis and AnalysisX-ray Diffraction in Crystallography

Buried Interface Modification Using Supercritical Carbon Dioxide

Xinqiao Jia、Thomas J. McCarthy2002-01-29Langmuir

Chemical modification of the buried interfaces between silicon wafers and either polystyrene or poly(methyl methacrylate) (PMMA) with the reagent (tridecafluoro-1,1,2,2-tetrahydrooctyl)dimethylchlorosilane (FDCS) was studied using liquid and supercritical carbon dioxide as the solvent and infusing agent. Above the cri…

Surface Modification and SuperhydrophobicityPhase Equilibria and ThermodynamicsPolymer Foaming and Composites

Quantum Size Effects in Carbon Nanotube Intramolecular Junctions

Alain Rochefort、Phaedon Avouris2002-01-29Nano Letters

We calculated the effect of varying the length of a metal-semiconductor carbon nanotube junction on its electrical properties. Joining a metallic (5,5) tube to a semiconducting (10,0) tube leads to the creation of new states near the Fermi energy and produces a larger conductance gap (about 2 eV) than the band gap of…

Carbon Nanotubes in CompositesMechanical and Optical ResonatorsNanotechnology research and applications

Absorption and Exciton Emission by an Aggregated Cyanine Dye Occluded within Mesoporous SBA-15

Wei Xu、Daniel L. Akins2002-01-29The Journal of Physical Chemistry B

We report the formation of monomeric and J-aggregated 1,1‘-diethyl-3,3‘-di(4-sulfobutyl)-5,5‘,6,6‘-tetrachlorobenzimidazolocarbocyanine (referred to as TDBC) encapsulated within a silicate mesostructure, specifically SBA-15, under different pH conditions. To facilitate incorporation of TDBC, it was necessary to functi…

Mesoporous Materials and CatalysisPorphyrin and Phthalocyanine ChemistryPolyoxometalates: Synthesis and Applications

Investigation on lanthanide-doped Y2O3 nanopowders obtained by wet chemical synthesis

Stefano Polizzi、M. Battagliarin、Marco Bettinelli 等 5 位作者2002-01-29Journal of Materials Chemistry

Trivalent europium or erbium doped yttria samples obtained by a wet chemical synthesis procedure have been investigated by wide and small angle X-ray scattering, scanning and transmission electron microscopy and luminescence spectroscopy. On the micron scale the powders obtained are large, compact aggregates built up…

Luminescence Properties of Advanced MaterialsPerovskite Materials and ApplicationsQuantum Dots Synthesis And Properties

Photoluminescent organic–inorganic composite films layer-by-layer self-assembled from the rare-earth-containing polyoxometalate Na9[EuW10O36] and poly(allylamine hydrochloride)

Yonghui Wang、Xinlong Wang、Changwen Hu 等 4 位作者2002-01-29Journal of Materials Chemistry

Photoluminescent organic–inorganic composite films incorporating the rare-earth-containing polyoxometalate Na9[EuW10O36] (EW) and poly(allylamine hydrochloride) (PAH) have been prepared by the layer-by-layer self-assembly method. UV-vis spectroscopy and ellipsometry were used to follow the fabrication process of the E…

Conducting polymers and applicationsPolymer Surface Interaction StudiesPolyoxometalates: Synthesis and Applications

Structural characteristics and moisture sorption behavior of nylon‐6/clay hybrid films

Shigemitsu Murase、Atsushi Inoue、Yoshiharu Miyashita 等 5 位作者2002-01-29Journal of Polymer Science Part B Polymer Physics

Abstract The structure of nylon‐6 hybrids with synthetic or natural clays was investigated for melt‐pressed films with Fourier transform infrared spectroscopy, wide‐angle X‐ray diffraction, and differential scanning calorimetry in comparison with the nylon‐6 homopolymer. In contrast to the development of familiar α‐fo…

Advanced Sensor and Energy Harvesting MaterialsPolymer Nanocomposites and PropertiesDielectric materials and actuators

Surface characterization of vinyl polymer–silica colloidal nanocomposites using X-ray photoelectron spectroscopy

M. J. Percy、Javier I. Amalvy、C. Barthet 等 7 位作者2002-01-29Journal of Materials Chemistry

We report the use of X-ray photoelectron spectroscopy (XPS) to characterize the surface compositions of colloidal nanocomposite particles. Each nanocomposite was synthesized by (co)polymerizing 4-vinylpyridine in the presence of an ultrafine silica sol. Thus, nitrogen and silicon were utilized as unique elemental mark…

Asphalt Pavement Performance EvaluationPolymer Nanocomposites and PropertiesSurfactants and Colloidal Systems

In Situ EXAFS Study To Probe Active Centers of Ru Chalcogenide Electrocatalysts During Oxygen Reduction Reaction

I. V. Malakhov、S. G. Nikitenko、Elena R. Savinova 等 5 位作者2002-01-29The Journal of Physical Chemistry B

Novel cluster Ru chalcogenide materials Mo x Ru y Se z and Ru x Te y were studied in situ using EXAFS in the transmission mode during the oxygen reduction reaction. Reversible changes in the structure of the active center were revealed for the electrochemical reaction as a function of the applied electrode potential.…

Electrocatalysts for Energy ConversionQuantum Dots Synthesis And PropertiesChalcogenide Semiconductor Thin Films