Materials Literature
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We present a statistical-mechanical theory of the formation of a macroscopic random network built from elementary units. These units represent atoms or small molecules that can form up to p permanent covalent bonds. As the number of formed bonds is increased, we observe a continuous phase transition from a fluid phase…
Here we study the dynamics of a bubble or drop as it is driven by a pressure gradient through a capillary tube. For the case of a straight capillary, the drop can either approach a steady-state shape or the rear of the drop develops a re-entrant cavity. Also, depending on the initial conditions, the drop can break apa…
General objectives experimental methods measures for the polymer concentration segment-molar excess Gibbs free energies how to use the data tables vapour pressures of binary polymer solutions Redlich-Kister parameters for the segment-molar excess Gibbs free energies of binary polymer solutions weight fraction Henry-co…
The performance factors which will influence the market acceptance of electrochromic windows are reviewed. A set of data representing the optical properties of existing and foreseeable electrochromic window devices was generated. The issue of reflective versus absorbing electrochromics was explored. This data was used…
The paper presents the results of a study investigating the energy performance of electrochromic windows under a variety of state-switching control strategies. We used the DOE-2.1E energy simulation program to analyze the annual cooling, lighting, and total electricity use and peak demand as a function of glazing type…
Minimum inhibitory concentration (MIC) studies were conducted to observe synergistic, antagonistic or additive effects produced by combinations of butyl paraben, ethyl paraben, methyl paraben, and propyl paraben against mycelial growth of mycotoxigenic species of Aspergillus, Fusarium, and Penicillium. On an individua…
Abstract Reactive melt‐processing of poly(styrene‐ co ‐maleic anhydride) (SMA) with primary N ‐alkylamines was carried out in one step in a twin‐screw extruder. Ring formation of the imide occurred within the residence time of the extruder, at temperatures exceeding 220°C and with an excess of primary amines. The incr…
Abstract Surface grafting of polymeric materials, such as films and fibers, may improve their reactive surface properties. Polypropylene active sites that should initiate a surface postgrafting can be formed by either nitrogen cold plasma or an electron‐beam irradiation. The plasmamodified polymer surface is cross‐lin…
We report results from cathodoluminescence spectroscopy of boron nitride films grown on Si(100) substrates by ion-source-assisted magnetron sputtering of a hexagonal BN target. Three main peaks are observed in the near-band-gap region for hexagonal boron nitride films at energies of 4.90, 5.31, and 5.50 eV. We also re…
Microcrystalline silicon (μ-Si) thin films were anodized in dilute HF solutions in the same manner as forming porous materials. It is demonstrated for the first time that the anodized μ-Si thin films show strong violet luminescence (415 nm) at room temperature. Visible green and red emissions were also observed accomp…
Calorimetric and optical reflectivity studies on free-standing partially fluorinated liquid-crystal films have revealed novel melting phenomena. The smectic-$A$-isotropic transition occurs through a series of layer-thinning transitions, causing the films to thin in a stepwise manner as the temperature is increased. Th…
We have performed molecular dynamics simulations of a supercooled atomic liquid. The self-intermediate-scattering function in the $\ensuremath{\beta}$-relaxation regime has a power-law time dependence and temperature dependence consistent with the mode-coupling-theory prediction of a von Schweidler law, with exponents…
In an effort to prepare crystals and determine the structure of alpha-thrombin complexed to a synthetic peptide inhibitor (MDL-28050) of the hirudin 54-65 COOH-terminal region, it was discovered that the crystals were not those of the complex but of gamma-thrombin. Gel electrophoresis studies revealed that autolytic d…
In a simple one-pot reaction the host-guest compounds 1 (white spheres FeIII; black = FeII; gray = NH; angled rods = 2: R = Me, Et) are accessible in gram quantities by self-assembly. They are the only fully characterized redox isomers whose cyclic voltammograms display four quasi-reversible waves and whose mixed-vale…
The substitution pattern determines whether distilbenylazobenzene compounds 1 or their subsequent products, the dihydrocinnolines 2, are isolated in the cobalt-catalyzed solvent-free reaction of azo compounds with diphenylacetylene. For several derivatives a photochromic equilibrium exists between the two forms.
No bonding interactions exist between the three interpenetrating framework structures in 1, and all of the two-dimensional networks are constructed by coordinate linkages-these two principles describe the structure of 1 (shown schematically on the right). Compound 1 was prepared from K2[Cd(CN)4], Ag-NO3, and pyrazine…
Liquid-Crystalline behavior over a wide temperature range and reversible phase transitions are observed for the polymer network 1, which is held together by hydrogen bonds between benzoic acid and pyridyl units
Up to fourth-generation neutral phosphorus-containing dendrimers are prepared in good yields in the synthesis outlined here. The only byproducts are NaCl and H2O, and the products contain highly reactive functional groups along the periphery. The first-generation dendrimer is shown on the right.
Abstract The role of metalloenzymes in important biological transformations has attracted increasing attention over the past several decades. Of the many chemical transformations mediated by enzymes, few are as challenging as multielectron redox reactions. Recent studies have revealed a partial structural and mechanis…
Mechanisms of guanosine triphosphate (GTP) hydrolysis by members of the G protein alpha subunit-p21ras superfamily of guanosine triphosphatases have been studied extensively but have not been well understood. High-resolution x-ray structures of the GTP gamma S and GDP.AlF4- complexes formed by the G protein Gi alpha 1…