Materials Literature
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In this issue of PNAS, Chen et al. (1) show feasibility for producing a highly sensitive biosensor, capable of detecting nanomolar quantities of biologically interesting molecules in “real time.” If the phenomenon can be generalized to other systems, it could have significant implications for a wide variety of fields,…
We study an alloy system where short-ranged, thermally-driven diffusion competes with externally imposed, finite-ranged, athermal atomic exchanges, as is the case in alloys under irradiation. Using a Cahn-Hilliard-type approach, we show that when the range of these exchanges exceeds a critical value, labyrinthine conc…
A tetrasubstituted derivative of 1,4,7,10-tetraazacyclododecane with amide coordinating groups and extended noncoordinating phosphonate groups forms a complex with gadolinium(III) (shown in the picture) which contains one slowly exchanging inner-sphere water molecule (tau(M)=21 µs). The 20-MHz water proton relaxivity…
The preparation, characterization, and X-ray structure are reported for the single-molecule magnet (PPh 4 )[Mn 12 O 12 (O 2 CPh) 16 (H 2 O) 4 ]·8(CH 2 Cl 2 ) ( 2 ). Complex 2 crystallizes in the triclinic space group P 1̄, which at 213 K has a = 17.2329(2), b = 17.8347(2), c = 26.8052(2) Å, α = 90.515(2), β = 94.242(2…
The fluorescence of a polyanionic conjugated polymer can be quenched by extremely low concentrations of cationic electron acceptors in aqueous solutions. We report a greater than million-fold amplification of the sensitivity to fluorescence quenching compared with corresponding "molecular excited states." Using a comb…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTPolymeric Systems for Controlled Drug ReleaseKathryn E. Uhrich, Scott M. Cannizzaro, Robert S. Langer, and Kevin M. ShakesheffView Author Information Department of Chemistry, Rutgers University, Piscataway, New Jersey 08854-8087 Department of Chemical Engineering, Massachuse…
<div class="htmlview paragraph">Classical approaches to pollution control have been to develop benign, non-polluting processes or to abate emissions at the tailpipe or stack before release to the atmosphere. A new technology called PremAir<sup>®</sup> Catalyst Systems<span class="xref">1</sp…
<div class="htmlview paragraph">The LEV/ULEV emission standards pose challenging problems on automotive exhaust gas treatment. This increases the need for good catalytic converter models, which can be applied for control. A dynamic converter model was made on the basis of first principles, accounting for the acc…
We model driven two-dimensional charge-density waves in random media via a modified Swift-Hohenberg equation, which includes both amplitude and phase fluctuations of the condensate. As the driving force is increased, the defect density first increases and then decreases. Furthermore, we find switching phenomena, due t…
A two-dimensional lattice gas model of network-forming particles on a triangular lattice is studied by the grand canonical Monte Carlo method. The effects of association and cooperative interactions, which lead to a weakening of the association interaction, are considered. Phase diagrams for several systems are presen…
The exposure of silicones to atomic oxygen in low Earth orbit causes oxidation of the surface, resulting in conversion of silicone to silica. This chemical conversion increases the elastic modulus of the surface and initiates the development of a tensile strain. Ultimately, with sufficient exposure, tensile strain lea…
<div class="htmlview paragraph">Automotive exhaust emission regulations are becoming progressively stricter due to increasing awareness of the hazardous effects of exhaust emissions. The main challenge to meet the regulations is to reduce the emissions during cold starts, because catalytic converters are ineffec…
Perovskite barium strontium titanate Ba0.5Sr0.5TiO3(BST) thin films were grown on (001) LaAlO3 (LAO) using pulsed-laser ablation. The microstructures of the as-grown BST films were studied with selected electron diffraction, transmission electron microscopy, and scanning transmission electron microscopy. The BST thin…
To investigate the role of the perovskite layers on fatigue behaviors, SrBi2Ta2O9(SBT) and Bi3TiTaO9 (BTT) films were prepared by pulsed laser deposition using 15% Bi-excess bulk targets. The SBT and the BTT films grown at the similar deposition conditions showed similar growth behaviors, electrical properties, and re…
We have imaged the electric-field-dependent structure of charge-density waves (CDWs) in ribbonlike ${\mathrm{NbSe}}_{3}$ single crystals by monochromatic x-ray topography. Below the depinning threshold ${E}_{T}$ the CDW is well correlated. Just above ${E}_{T}$, the CDW shears along longitudinal steps in crystal thickn…
We report high resolution angle-scanned photoemission and Fermi surface (FS) mapping experiments on the layered transition-metal dichalcogenide $1T\ensuremath{-}{\mathrm{TaS}}_{2}$ in the quasicommensurate (metallic) and the commensurate (insulating) charge-density-wave (CDW) phase. Instead of a nesting induced partia…
We report the observation of size dependent structural disorder by x-ray absorption near-edge spectroscopy (XANES) in InAs and CdSe nanocrystals 17--80 \AA{} in diameter. XANES of the In and Cd ${M}_{4,5}$ edges yields features that are sharp for the bulk solid but broaden considerably as the size of the particle decr…
<div class="htmlview paragraph">This paper investigates engine performance with a stable emulsified fuel including frying oil, composed of vegetable oils discarded from restaurants and households. To reduce the oil viscosity, equal proportions of used frying oil and gas oil were mixed and emulsions of this blend…
Artificial (LaMnO3)m(SrMnO3)n superlattices, n/(m+n)=0.26, were grown with pulsed-laser deposition, and the superlattice period Λ was varied. Their structural characteristics were investigated using x-ray diffraction and electron microscopy. When Λ&lt;ap (perovskite lattice parameter), bulk-like properties of La0.…
Sulfolobus solfataricus is a hyperthermophilic archaeon growing optimally at 80-85 degrees C. It metabolizes glucose via a novel non-phosphorylated Entner-Doudoroff pathway, in which the reversible C(6) to C(3) aldol cleavage is catalysed by 2-keto-3-deoxygluconate aldolase (KDG-aldolase), generating pyruvate and glyc…