Materials Literature
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We report on low-temperature photoconductivity (PC) in n-PbTe(Ga) epitaxial films prepared by the hot-wall technique on <111>-BaF_2 substrates. Variation of the substrate temperature allowed us to change the resistivity of the films from 10^8 down to 10_{-2} Ohm x cm at 4.2 K. The resistivity reduction is associated w…
Surface glass transition temperature,, of monodisperse polystyrene (PS) films was determined from the temperature dependence of lateral force at a given scanning rate. The end groups of the PS were composed of sec -butyl group and a repeating unit terminated by proton. of the PS films was discerned to be markedly lowe…
ADVERTISEMENT RETURN TO ISSUEPREVCommunicationNEXTLayered, Erasable, Ultrathin Polymer FilmsSvetlana A. Sukhishvili and Steve GranickView Author Information Department of Materials Science and Engineering University of Illinois at Urbana-Champaign 104 South Goodwin Ave., Urbana, Illinois 61801 Cite this: J. Am. Chem.…
This paper addresses numerical simulation of damage and fracture in concrete from the impact and penetration of shaped charge jets. We have modeled the jet penetration process with CALE, a two dimensional arbitrary Lagrange Eulerian hydrocode. We have looked at several constitutive models ranging from simple pressure…
Five θ-type BETS salts [BETS = bis(ethylenedithio)tetraselenafulvalene], θ-BETS 2 RbCo(SCN) 4, θ-BETS 2 RbZn(SCN) 4, θ-BETS 2 CsCo(SCN) 4, θ-BETS 2 CsZn(SCN) 4, and θ-BETS 2 Ag(CN) 2, have been newly prepared by the electrocrystallization method. The crystal structure analyses indicate that the former four salts are i…
Regioregular polymers poly(3-alkyl-2,5-thienylene- alt -1,4-phenylene) (PBTC n, n = 4, 8, 12) and poly[1,4-bis(3-alkyl-2-thienyl)phenylene] (PBTBC n, n = 4, 8, 12), which contain alternating phenylene and substituted thienylene or bithienylene repeating units, have been chemically and/or electrochemically synthesized…
The synthesis, characterization, absorption, and emission spectra of MoSe2 and WSe2 nanoclusters are reported. These nanoclusters are about 3.5−6 nm (MoSe2, see graphic) and 4−7 nm (WSe2) in diameter, as measured by TEM imaging. The particles are strongly quantum confined and highly anisotropic. Electron diffraction r…
ADVERTISEMENT RETURN TO ISSUEPREVCommunication to the...Communication to the EditorNEXTSynthesis of a New Hyperbranched Poly(silylenevinylene) with Ethynyl FunctionalizationYingxin Xiao, Richard A. Wong, and David Y. SonView Author Information Department of Chemistry, P.O. Box 750314, Southern Methodist University, Da…
Nitrogenous bases have commonly been employed as axial ligands for metalloporphyrins in biomimetic model compounds and catalytic oxygenation chemistry. The addition of bases such as pyridines or imidazoles to metalloporphyrin-catalyzed hydrocarbon oxidation reactions is known to affect catalyst selectivity and turnove…
Fluoro-terminated hyperbranched poly(ether ketone)s (FHBPEKs) with controlled degrees of branching and their linear analogous poly(ether ketone) (LPEK) whose chemical structure and molecular weights were similar to those of FHBPEKs were synthesized and characterized. Depending on the amount of the core molecules, degr…
The generation of superbase sites by doped alkali metals (Li, Na, and K) on alkaline earth metal oxides (MgO, CaO, SrO, and BaO) has been examined. In catalytic activity for the double bond migration of 4,4-dimethyl-1-pentene and 2,3-dimethyl-1-butene, a large increase in the generation of superbase sites was observed…
The thyminylmethyl radical and the 2‘-deoxyuridin-1‘-yl radical were studied. The former radical was produced in laser flash photolysis (LFP) studies from two precursors derived from thyminylacetic acid, the N -hydroxypyridine-2-thione ester (PTOC ester), and the phenylselenyl ester. The thyminylmethyl radical has an…
Two triazole derivatives were synthesized, and their inhibiting ability for scaling and corrosion process was checked using various electrochemical techniques. Potentiodynamic polarization studies clearly reveal the fact that triazole derivatives are good mixed-type inhibitors. Electrochemical impedance spectroscopy m…
The adsorption of CO on Al 2 O 3, ZrO 2, ZrO 2 −SiO 2, and ZrO 2 −La 2 O 3 supported Pd catalysts was studied by adsorption microcalorimetry and infrared (IR) spectroscopy. Some interesting and new correlations between the results of microcalorimetry and IR spectroscopy have been found. The CO is adsorbed on palladium…
Pentaheptites (three-coordinate tilings of the plane by pentagons and heptagons only) are classified under the chemically motivated restriction that all pentagons occur in isolated pairs and all heptagons have three heptagonal neighbors. They span a continuum between the two lattices exemplified by the boron nets in T…
Core−shell type micelles with a hydrodynamic diameter of 52 nm composed of 38 molecules of zinc dendrimer porphyrin with 32 carboxylate groups on the periphery and 39 poly(ethylene glycol)−poly( l -lysine) (PEG−PLys) block copolymers were prepared at a stoichiometric mixing ratio. These micelles showed an unusually hi…
In this work, the displacement of a globular protein from the air/water interface by sodium dodecyl sulfate (SDS) was followed using a combination of the Langmuir−Blodgett method and atomic force microscopy. The results are compared to displacement of the same protein by the nonionic surfactant Tween 20. The displacem…
The dispersion process of laponite clay powder in water was investigated using light scattering. The complete dispersion process takes about 12 h. Laponite solutions were characterized in salt-free water and in 10 - 3 M NaCl using static and dynamic light scattering, which shows that laponite has a large size polydisp…
Synthetic strategies for preparing dimeric tetrathiafulvalenes (TTFs) linked by either one, two, or four bridges have been developed. In particular, we report efficient few-step protocols for the preparation of face-to-face overlapped quadruple-bridged bis-TTFs. The ready interconversion of cis and trans TTFs in the p…
The isostructural compounds of general formula Cu 2 Te 2 O 5 X 2 (X = Cl, Br) have been synthesized by chemical transport reaction. They crystallize in the tetragonal system, space group P 4̄ with a = 7.6209(3) Å, c = 6.3200(4) Å, and a = 7.8355(2) Å, c = 6.3785(2) Å for Cu 2 Te 2 O 5 Cl 2 and Cu 2 Te 2 O 5 Br 2 respe…