Materials Literature
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We use a parametrized linear combination of atomic orbitals calculations to determine the stability, optimum geometry, and electronic properties of nanometer-sized capped graphitic cones, called ``nanohorns.'' Different nanohorn morphologies are considered, which differ in the relative location of the five terminating…
ADVERTISEMENT RETURN TO ISSUEPREVCommunication to the...Communication to the EditorNEXTHigh-Throughput Measurement of Polymer Blend Phase BehaviorJ. Carson Meredith, Alamgir Karim, and Eric J. AmisView Author Information Polymers Division, National Institute of Standards and Technology, Gaithersburg, Maryland 20899 Ci…
Luminescent Eu-containing copolymers were synthesized through the copolymerization of Eu−complex monomers containing β-diketones with methyl methacrylate and characterized by FT-IR, UV−vis, XPS, GPC, TGA, and DSC. All these Eu copolymers are fully soluble in common organic solvents and can be cast into transparent, un…
We report measurements of photoconductivity and electric field induced photoluminescence quenching in three-dimensional close-packed solids of colloidal CdSe quantum dots. Our measurements suggest that photoexcited, quantum confined excitons are ionized by the applied electric field with a rate that depends on both th…
We report total energy and electronic structure calculations for ZnO in the B4 (wurtzite), B3 (zinc blende), B1 (rocksalt), and B2 (CsCl) crystal structures over a range of unit cell volumes. We employed both the local-density approximation (LDA) and the PBE96 form of the generalized gradient approximation (GGA) toget…
Atomic and electronic structures of neutral and anionic gold clusters $({\mathrm{Au}}_{N}$ and ${\mathrm{Au}}_{N}^{\ensuremath{-}},$ $2<~N<~10)$ are investigated using the density-functional theory with scalar-relativistic ab initio pseudopotentials and a generalized gradient correction. The ground state optimal…
Molecular dynamics simulations have been used to delineate the pressure dependence of conformational dynamics in polyethylene. Chain dynamics have been studied as a function of pressure (0−25 kbar) at 400 K and as a function of temperature (280−450 K) at an elevated pressure of 10 kbar. The volumetric glass transition…
An improved condensation model for the estimation of pore-size distribution in the range of nanometers is examined. In the authors' previous paper, the model proved its reliability in computer experiments employing the molecular dynamics technique. The model is tested here in a real experimental system with a MCM-41-l…
ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTChemical Modification of Transition Metal Upconversion Properties: Exchange Enhancement of Ni2+ Upconversion Rates in Ni2+:RbMnCl3Oliver S. Wenger, Daniel R. Gamelin, and Hans U. GüdelView Author Information Departement für Chemie und Biochemie Universität Bern, Freies…
Catalytic oxidation of glucose and cellulose has been demonstrated in a monolith reactor, a novel contacting device for the oxidation of carbohydrate feedstocks that allows the processing of nonsoluble components without reactor plugging. Catalytic enhancement is observed for glucose oxidation, and the catalyst promot…
A mesoporous silica FSM-16 was found to be a recyclable oxidizing promoter of arylmethyl bromides for the preparation the corresponding carboxylic acids, aldehydes, or ketones under photoirradiation conditions.
The chemical modification of PVC films with sodium azide and 4-aminothiophenol was investigated. Using mixtures of a good and a nonsolvent for PVC, reactions took place in a controlled way, and the films remained transparent and smooth. To obtain information about the surface selectivity of the reactions, the degree o…
Excitation profiles of SERS (surface-enhanced Raman scattering) and/or SERRS (surface-enhanced resonance Raman scattering) spectral bands of two forms of a Ag-bpy (bpy = 2,2'-bipyridine) surface complex and of [Ru(bpy)3]2+ on Ag nanoparticle (hydrosol) surfaces were determined from the spectra excited in the 458-600 n…
Colloidal CdSe quantum dots were chemisorbed on a gold electrode using a variety of self-assembled monolayers (SAMs) consisting of dithiols and rigid disulfides. After absorption of a photon with an energy larger than the band gap, a long-lived excited state is formed in the quantum dot; this state can decay by electr…
ADVERTISEMENT RETURN TO ISSUEPREVNoteMesomorphic Form of Syndiotactic PolypropyleneVittoria, Liberata Guadagno, Angiolina Comotti, Roberto Simonutti, Finizia Auriemma, and Claudio De RosaView Author Information Dipartimento di Ingegneria Chimica e Alimentare, Università di Salerno, via Ponte Don Melillo, Fisciano (Sal…
ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTNanoparticle Assemblies: "Rectified" Quantized Charging in Aqueous MediaShaowei ChenView Author Information Department of Chemistry, Southern Illinois University Carbondale, Illinois 62901-4409 Cite this: J. Am. Chem. Soc. 2000, 122, 30, 7420–7421Publication Date (Web)…
Polyanion/polycation multilayers floating at the air/water interface were prepared by consecutive adsorption of polyelectrolyte layers onto a Langmuir monolayer from aqueous polyelectrolyte subphase solutions. With the positively charged Langmuir monolayer headgroups of the lipid dimethyldioctadecylammonium bromide, t…
We have explored new possible phases of 3D C60-based fullerites using semiempirical potentials and ab-initio density functional methods. We have found three closely related structures - two body centered orthorhombic and one body centered cubic - having 52, 56 and 60 tetracoordinated atoms per molecule. These 3D polym…
The energetics of transformation of a planar fragment of a graphite monolayer into a spherical cluster is studied. The path considered is that a flat cluster rolls up into a segment of a spherical shell. The energy landscape of the process is presented. A simple model, formerly invented for calculating the carbon nano…
Transition metal oxide nanoparticles have been synthesized sonochemically from metal acetates. The metal oxide nanoparticles are characterized using X-ray diffraction (XRD), diffuse reflection spectroscopy (DRS), transmission electron microscopy (TEM), and BET nitrogen adsorption. The results of DRS are analyzed in de…