Materials Literature
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We report an experimental procedure to optimize the current profile of a focused ion beam probe, with a special emphasis on high resolution applications. The optimized operating conditions are given for three specific cases: specimen thinning for electron microscopy, nanoetching, and nanolithography. We present high q…
Inexpensive and efficient cellulose-based adsorbents were prepared by the reaction of cross-linked polyethylenimine (CPEI) with an agricultural waste (i.e., wood sawdust). Factors affecting the extent of amination, such a CPEI concentration, pH, time, and temperature of reaction as well as sawdust particle size range,…
Abstract Transport models of diffusion‐induced bubble growth and collapse in viscous liquids are developed and evaluated. A rigorous model for these important phenomena is formulated taking into account convective and diffusive mass transport, surface tension, and viscous and inertial effects. Predictions for bubble g…
Propagation of elastic waves near the cohesive limit of a solid is of interest in understanding the speed at which strain energy is transported in front of a mode-I crack tip. It can be argued that the crack propagation velocity is limited by how fast the strain energy can be transported ahead of the crack tip to sust…
X-ray crystal structures of three substituted 4,4‘-biphenyldiamines, namely, 2,2‘,6,6‘-tetramethylbenzidine (TMBZ), 2,2‘-dimethylbenzidine (DMBZ) and 2,2‘-bis(trifluoromethyl)benzidine (BFBZ), were determined. The torsional angles between the two phenyl rings for TMBZ, DMBZ, and BFBZ are φ = 83°, 75°, and 59°, respect…
To clarify further the mechanism of regulation by phosphorylation of isocitrate dehydrogenase, cocrystallization of isocitrate dehydrogenase and isocitrate dehydrogenase kinase/phosphatase in the presence of an ATP analog was attempted. Although cocrystallization was unsuccessful, a new crystal form of isocitrate dehy…
Two kinds of cadmium sulfide (CdS) particulate films have been generated in situ by exposing stearic acid (SA) Langmuir monolayer at the air−aqueous CdCl 2 interface to hydrogen sulfide (H 2 S) gas: particulate films composed of oriented rodlike nanocrystals (A-type particulate films), and those of dotlike nanocrystal…
Aluminosilicates were prepared by the sol−gel method using tetraethoxysilane as silica source and aluminum ethoxide, aluminum iso-propoxide, or aluminum sec -butoxide as alumina sources. An important effect of the alkylaluminum substitutes is observed in the BET specific area, ethoxide > isopropoxide > sec -butoxide.…
Curing bis(maleimide) (BMI) with diallylbisphenol A (DABPA) results in the formation of a high-performance thermoset resin. A variety of reactions in which maleimide units are converted to succinimide moieties have been proposed. In order to make spectral assignments for the fluorescence behavior observed during the c…
The fracture toughness G c of an interface between the immiscible homopolymers polystyrene (PS) and poly(2-vinylpyridine) (PVP) reinforced with random copolymers, dPS f − r -PVP 1- f was measured as a function of the average monomer fraction f and the areal chain density Σ of the copolymer. Long symmetric random copol…
The compound [Cu(cyclam)(TCNQ) 2 ](TCNQ) (cyclam = 1,4,8,11-tetraazacyclotetradecane, TCNQ = 7,7,8,8-tetracyanoquinodimethane) has been obtained in two different crystallographic forms, isomers 1 and 2 . Crystal data for isomer 1: triclinic, P 1̄, a = 7.855(6) Å, b = 10.267(2) Å, c = 14.424(3) Å, α = 95.42(2)°, β = 10…
The bonding of atomic oxygen on Pt(111) and Rh(111) was examined using density functional theory in order to understand their different chemical properties. The oxygen−surface interactions were modeled by bonding atomic oxygen to 10-atom clusters of Pt and Rh designed to model the (111) surface. Density functional the…
A series of alkyl and dialkylammonium polyacrylates were synthesized by neutralizing a 5000 molecular weight poly(acrylic acid) with alkyl- and dialkylamines. Their thermal stability was investigated using thermogravimetry. Their thermotropic liquid crystal behavior was analyzed using differential scanning calorimetry…
Reactions of nitridomanganese(V) porphyrins with chromium(III) porphyrins resulted in the irreversible formation of nitridochromium(V) porphyrins and manganese(III) porphyrins. The progress of these reactions has been followed spectrophotometrically, electrochemically, and spectroscopically by EPR. Kinetic analysis of…
Near-threshold photoelectron recapture due to postcollision interaction with a single Auger electron is examined within the quantum-mechanical framework of radiationless resonant Raman scattering. Model calculations using a hydrogenic approximation are performed, revealing general features of the escape probability as…
Water vapor adsorption and liquid penetration into thermally oxidized porous silicon films were studied by variable angle spectroscopic ellipsometry. Characterization of the surfaces in air combined with multilayer optical modeling showed the existence of a gradient in the volume porosity and bulk‐like silicon skeleto…
The crystal structures of potassium tetratellurite and potassium ditellurite are reported, completing the series of known phases of alkali tellurites including lithium, sodium, potassium and cesium. Potassium tetratellurite (K 2 Te 4 O 9, a = 7.572(1) Å, b = 17.821(3) Å, c = 7.829(1) Å, β = 108.62°, monoclinic, P 2 1…
Abstract The constant rate stretching of amorphous poly(ethylene terephthalate) films is the first step of the industrial “inverse” process. To study this process, films deformed under uniaxial planar symmetry conditions have been produced on a laboratory stretching machine in order to discuss the influence of macrosc…
Abstract A new family of cone‐shaped podands and barrel‐shaped cryptands based on calix[4]arenes incorporating 5,5′‐substituted 2,2′‐bipyridine subunits were prepared and characterized. The Eu 3+ and Tb 3+ complexes of the podands bearing two, three, or four bipyridine chromophores could be isolated. High molar absorp…
The Fourier transform infrared (FTIR) spectra and Raman spectra of fluorine-doped silicon oxide films capped by silicon nitride thin film to prevent water absorption from the air were measured as a function of the fluorine concentration in the films. It was found that fluorine doping diminishes the Si–OH bonds in film…