Materials Literature
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Polystyrene substrates were modified by radio-frequency plasma deposition from mixtures of various organic vapors (acetone, methane, methanol, and formic acid) and oxygen. The resulting surfaces exhibited a wide range of surface oxygen concentrations, as measured by electron spectroscopy for chemical analysis (ESCA).…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTInterfacial segregation in two-phase polymer blends with diblock copolymer additives: the effect of homopolymer molecular weightKevin H. Dai, Edward J. Kramer, and Kenneth R. ShullCite this: Macromolecules 1992, 25, 1, 220–225Publication Date (Print):January 1, 1992Publicati…
Siloxane–oxide hybrid coatings have been prepared via the hydrolysis–condensation of diethoxydimethylsilane and various metallic alkoxides, M(OR)n with M = Si, Ti, Zr and Al. The rheological behaviour of the precursor sols and their hydrophobic character due to the presence of methyl groups, allows the formation of fi…
The authors present the principles and application examples of a recently refined, computerised, surface photovoltage (SPV) method. This new method is capable of wafer-scale, non-contact mapping of metal contaminants in the bulk and on the surface with sensitivities as high at 10 10 atoms cm -3 . They demonstrate the…
Perovskite‐type (La 1‐ x Sr x )MnO 3 (0 x 0.3) was synthesized through the sol–gel process at low temperature (400° to 500°C). Poly(acrylic acid) (PAA) was used to make a gel from an aqueous solution of lanthanum, strontium, and manganese nitrates. The particle‐diameter distribution of the manganites had a maximum val…
Fluorescence and fluorescence excitation spectra have been measured for solid solutions of tetrathiophene in tetradecane at 12 and 4.2 K. At 4.2 K, the spectra exhibit full vibrational resolution {inhomogeneous origin [full width at half-maximum, (FWHM)] approximately 5 cm−1 }. Narrow band excitation and detection est…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTMolecular recognition via base pairing: photoinduced electron transfer in hydrogen-bonded zinc porphyrin-benzoquinone conjugatesAnthony Harriman, Yuji Kubo, and Jonathan L. SesslerCite this: J. Am. Chem. Soc. 1992, 114, 1, 388–390Publication Date (Print):January 1, 1992Publi…
The \ensuremath{\alpha}-relaxation dynamics in a hard-sphere system is studied solving microscopic-mode-coupling equations. The solutions for coherent and incoherent dynamical structure factors, the transversal correlation functions, and the moduli are presented for all wave vectors. The wave-vector dependence of fitt…
There are a number of calculations in the literature of the effect of statistical surface roughness on the specular and diffuse scattering of neutrons and x rays which impinge on surfaces at grazing incidence. These calculations do not agree with one another and in some cases lack internal consistency. In this paper I…
We present the method and results of two phase-separation experiments performed on the binary-polymer blend polyisoprene-poly(ethylene-propylene). Elastic light scattering and optical microscopy were used to follow the phase separation after quenches into the coexistence region of the phase diagram. For off-critical q…
From the specific-heat (${\mathit{C}}_{\mathit{p}}$) measurements on the isostructural ${\mathrm{NH}}_{4}$L(${\mathrm{SO}}_{4}$${)}_{2}$\ensuremath{\cdot}${4\mathrm{H}}_{2}$O (L=La, Ce, Pr, Nd, Sm, Eu, Gd, and Tb) Tb) crystals at 100 K T300 K, it is shown that these crystals undergo two structural phase transitions, $…
Abstract Large single crystals of orthorhombic K 2 ZnCl 4 with optical quality have been grown by the Czochralski method. The elastic constants and their temperature and pressure derivatives have been determined from ultrasonic resonance frequencies of thick plates of different orientation and the shift of these frequ…
Abstract
L'Altiplano est un vaste bassin fermé de 200 000 km2 situé à 4000 m d'altitude entre les Cordillères Orientale et Occidentale des Andes. Le climat est sec et froid, avec une pluviosité toujours nettement inférieure à l'évapo ration potentielle. L'Altiplano bolivien renferme un des plus beaux ensembles de bassins évapo…
Abstract Four soil profiles, uncultivated and cultivated examples of Akuse and Prampram series from the Accra Plains of Ghana, developed in situ from garnetiferous hornblende gneiss, were examined in this study to establish their physical and chemical properties, macromorphology, micromorphology, and mineralogy. Crack…
Bei der Erforschung der Struktur der Materie spielen seit den zwanziger Jahren dieses Jahrhunderts Teilchenbeschleuniger eine wichtige Rolle. Sie liefern die für die Experimente mit Atomkernen oder El
This paper describes criteria and formulas adopted in developing a new computer program capable of evaluating the geometric evolution of a cylindrical star grain during its combustion. This computer program, named STAR, calculates the burning perimeter (or burning area), the wet perimeter, and port area as functions o…
A versatile experimental setup is presented for both x-ray standing waves (XSW) and x-ray photoemission spectroscopy (XPS) studies in an energy range up to 7 keV. The compact apparatus operates under ultrahigh vacuum and includes in situ sample preparation and characterization techniques. For the XSW scans the inciden…
1. Introduction. 2. Characteristics of Metal Surfaces. Physical surface and adsorption on the surface. Geometric characteristics of surfaces. Physical characteristics. Stresses in surface layers. Mechanical characteristics of surfaces. Chemical characteristics. 3. Characteristics of Surface Layers after Various Method…
Yellow‐browning of the ethylene‐vinyl acetate (EVA) copolymer encapsulant used in PV modules has resulted in significant power losses of over 50% of the initial power output. The weathering‐degraded yellow‐brown EVA films have lost the ultraviolet (UV) absorber, Cyasorb UV 531(R), and the degree of cross‐linking (gel…