Materials Literature
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Zeolite A provides a suitable environment to host Ag2S and PbS clusters, so that spectroscopic investigations on very small particles are possible. The Ag2S monomer is colorless and shows photoluminescence at 490 nm with a lifetime of 300 micros, while the absorption and luminescence of Ag4S2 and larger clusters are r…
Nanoscale sliding friction involving a polystyrene melt near its glass transition temperature Tg (373 K) exhibited dissipation phenomena that provide insight into the underlying molecular relaxation processes. A dissipative length scale that shows significant parallelism with the size of cooperatively rearranging regi…
The ability of polyoxometallates (POM), molecular-anionic metal oxides, to act as photocatalysts in the electron transfer from organic substrates to metal ions will be presented. In the process, illumination at the O → M charge-transfer band (near-visible and UV regions), renders POM strong oxidants able to abstract e…
The formation enthalpies by in situ direct synthesis calorimetry for a series of silver alkanethiolates, AgS(CH 2 ) n CH 3, with various long chain-length substituents ( n = 9, 11, 15, and 17) are reported. The calorimetric results support a mechanism of stepwise hierarchical assembly involving primary directional int…
Nanocable devices (see Figure) of individual single-walled carbon nanotube/polypyrrole (PPy) and their synthesis, transport studies, and chemical-sensing applications are investigated. They exhibit suppressed conductance, in contrast to the anticipated combined conductance from the nanotubes and PPy. Further depositio…
In this paper, we report a new approach to fabricate gold nanowires by controlling the volume of the growth solution. The shape evolutions ranging from fusiform nanoparticles to 1-D rods were observed. Increasing the addition of the growth solution can control the length of nanorods. The length of the rods can be exte…
Density functional methods were used to study the environmental dependence of O vacancy formation in CeO2. It was found that an O vacancy in the 2+ charged state has the lowest formation energy for a wide range of Fermi energies (EF) from 0 to ∼1.9eV, while a neutral vacancy becomes the most stable at higher EF values…
A series of cardenolides and related compounds have been isolated from the aerial parts and roots of the ornamental milkweed, Asclepias curassavica. Their structures were determined by spectroscopic and chemical methods. Among them, three derivatives of calactinic acid methyl ester (13-15), 19-nor-16 alpha-acetoxy-10…
Abstract A nanosize CaCO 3 filler was synthesized by an in situ deposition technique, and its size was confirmed by X‐ray diffraction. CaCO 3 was prepared in three different sizes (21, 15, and 9 nm). Styrene–butadiene rubber (SBR) was filled with 2–10 wt % nano‐CaCO 3 with 2% linseed oil as an extender. Nano‐CaCO 3 –S…
Abstract Filtration paper was coated with a thin polyaniline film. The content of conducting polymer was 8.2 and 6.3 wt % for polyaniline hydrochloride and polyaniline base, respectively. After burning, the coated material retains the original fibrilar morphology of cellulose. The polyaniline coating converts to solid…
[reaction: see text] A new [3 + 3] Schiff base macrocycle incorporating naphthalene groups has been prepared. By examination of its properties, X-ray crystallography of model compounds, and calculations, it has been determined that the macrocycle exists predominantly as the keto-enamine tautomer. This unexpected tauto…
Conduction in thin films of PbSe nanocrystals doped by electrochemical gating has been studied. Charging the film, with either electrons or holes, increases the conductance by orders of magnitude. The electrons in the 1S(e) state of nanocrystals in these films have a mobility as high as 5.0 x 10(-3) cm(2) V(-1) s(-1).…
Adsorption of oxygen atoms, achieved via electron-induced dissociation of nitrogen dioxide, induces restructuring of the ``herringbone'' to a striped, soliton-wall structure accompanied by release of gold from the ``elbows'' in the herringbone structure. The number density of ``elbows'' (dislocations corresponding to…
Acid-treated carbon nanotubes are reacted with metal halides and water and are then calcined to produce a chemically bonded oxide layer of controllable thickness on the nanotubes (see figure). Similar coatings are prepared on aluminum oxide and silicon nanowires by the reaction of the metal halides with the surface hy…
Combinatorial materials science requires parallel advances in materials characterization. A high-throughput nanoscale synthesis/nanomechanical profiling approach capable of accurately screening the mechanical properties of 1,700 photopolymerizable materials (see Figure, scale bar: 100 μm) within a large, discrete poly…
Abstract There are many variables in the preparation of aqueous polyurethane (PU) dispersions. Carboxylic acid content, solid content, degree of pre/postneutralization of the carboxylic acids, and chain extension all impact dispersion particle size, viscosity, pH, molecular weights, and glass transition temperature. T…
An extended enzymatic hydrolysis of cotton fibers by crude cellulase from Trichoderma pseudokoningii S-38 is described with characterization of both the enzyme changes of activities and cellulose structure. The hydrolysis rates declined drastically during the early stage and then slowly and steadily throughout the who…
Magnetic nanostructures on non-magnetic or magnetic substrates have attracted strong attention due to the development of new experimental methods with atomic resolution. Motivated by this progress we have extended the full-potential Korringa-Kohn-Rostoker (KKR) Green function method to treat non-collinear magnetic nan…
This article describes a simple heat model of the vacuum arc remelting (VAR) process that includes solution of the nonlinear heat conductivity equation with the nonlinear boundary conditions which are typical for VAR process. The finite-difference analogue of the model equations was obtained through the finite volume…
Zr precipitates in Al to form the phase Al3Zr. For a low supersaturation in Zr of the fcc solid solution, it has been observed that during the precipitation first steps the Al3Zr precipitates have the metastable L12 structure and that they transform themselves to the stable DO23 structure for long enough annealing tim…