A rotaxane with two rigidly held porphyrins as stoppers
A rotaxane with two rigidly held porphyrins as stoppers is synthesized by a copper(I)-based template strategy.
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The validation of the thermal step method
The validation of the thermal step method, which makes it possible to determine the electric field and the space charge distributions in insulating materials, is described. Validation was done by testing the numerical treatment, and then by depositing real corona charges in a well-localized zone of the sample. Other v…
Hybridized nearly-free-electron tight-binding-bond approach to interatomic forces in disordered transition-metal alloys. II. Modeling of metallic glasses
We present an atomistic simulation of the structure of transition-metal glasses based on inter-atomic forces derived from quantum theory. Using the inter-atomic potentials calculated within the hybridized nearly-free-electron tight-binding-bond theory introduced in the preceding paper, we construct models for Ni-Y, Ni…
Endothelial cell growth on oxygen-containing films deposited by radio-frequency plasmas: the role of surface carbonyl groups
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).…
Interfacial segregation in two-phase polymer blends with diblock copolymer additives: the effect of homopolymer molecular weight
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…
Sol–gel synthesis of siloxane–oxide hybrid coatings [Si(CH 3 ) 2 O·MO x : M = Si, Ti, Zr, Al] with luminescent properties
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…
Non-contact mapping of heavy metal contamination for silicon IC fabrication
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…
Synthesis of Perovskite‐Type (La 1− x Sr x )MnO 3 (O X 0.3) at Low Temperature
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…
The lowest energy singlet state of tetrathiophene, an oligomer of polythiophene
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…
Molecular recognition via base pairing: photoinduced electron transfer in hydrogen-bonded zinc porphyrin-benzoquinone conjugates
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…
Primary relaxation in a hard-sphere system
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…
Neutron scattering by rough surfaces at grazing incidence
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…
Light-scattering experiments on phase-separation dynamics in binary fluid mixtures
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…
Low-temperature structural phase transitions inNH4L(SO4)2⋅4H2O (L=La–Dy): Specific-heat measurements
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, $…
Physical Properties of K2ZnCl4
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…
Trends and anomalies in the thermodynamics of gaseous thorium and uranium halides
Abstract
Géochimie des lacs salés et croûtes de sel de l'altiplano bolivien / Geochemistry of saline lakes and salt crusts of the bolivian altiplano / Geoquimica de los lagos salados y costras salinas del altiplano boliviano
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…
Micromorphology and Mineralogy of Cracking Soils from the Accra Plains of Ghana
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…
Physik der Teilchenbeschleuniger und Synchrotronstrahlungsquellen
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
Generalized geometric analysis of right circular cylindrical star perforated and tapered grains
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…