Materials Literature
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Abstract Polyacrylonitrile (PAN) films were made by casting a dimethyl sulphoxide (DMSO) solution. After drying, the films were uniaxially drawn by an essentially solid‐state drawing procedure. Using polarised‐infrared (IR) spectroscopy, the dichroism of the nitrile‐stretching vibration was monitored as a function of…
Local atomic arrangements and wide tilings for two types of decagonal quasicrystals, which are formed in alloys with compositions near Al70Ni15Co15, were studied by high-resolution electron microscopy. The decagonal quasicrystals can be interpreted as structures formed with different tilings, so-called rhombic and pen…
Based on literature data and experimental findings at the Jet Propulsion Laboratory (JPL), semiconductors with the skutterudite structure TPn3 (where T is a transition metal element such as Co, Rh, Ir, Ni, and Pd, and Pn is a pnicogen element such as P, As, and Sb) possess attractive characteristics and show a good po…
Two‐dimensional Al 2 O 3 and SiC woven laminate composites, and oxide and nonoxide monolithic ceramics with 5 to 10 wt% of polycarbosilane binder, were consolidated up to 75% of TD (theoretical density) at 1150°C by the multiple impregnations of a polycarbosilane solution. The processing conditions were optimized with…
Webs of Kapton 200-H and Upilex-S polyimide films were treated using oxygen plasma prior to sequential sputter deposition of chromium and copper in a roll metallization system. Two plasma system configurations were employed for treatment. In one configuration, the sample traveled downstream from a microwave plasma; in…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTElectron paramagnetic resonance studies of metalloporphyrin anion radicals. Effects of solvent, counterion, temperature, and isotopic substitution on the Jahn-Teller active 2Eg ground stateJyoti Seth and David F. BocianCite this: J. Am. Chem. Soc. 1994, 116, 1, 143–153Public…
The molecular first hyperpolarizabilities (β) of a series of asymmetric squaraine dyes have been measured by electric-field-induced second harmonic generation; the dyes have negative β-values whose magnitudes are comparable to 4-N,N-dimethylamino-4′-nitrostilbene (DANS).
Two new azide-containing complexes [Cu2(dmaeoxd)(N3)2(H2O)2]1 and [{Cu2(dmaeoxd)(N3)2}n]2{H2dmaeoxd =N,N′-bis[2-(dimethylamino)ethyl]oxamide} have been synthesized and characterized by single-crystal X-ray diffraction methods: 1, triclinic, space group P= 8.620(3), b= 9.824(3), c= 11.216(3)Å, α= 85.56(3), β= 86.90(3),…
ITO thin films were prepared at 550°C by a sol-gel method using colloidal particles derived from a solution of indium nitrate and tin chloride. The colloidal particles were secondary particles with about 50nm in diameter and were dispersed by adding indium chloride as a peptizer to prepare a dipping solution. Firing o…
In the present work, the electronic structure of polythiophene at several doping levels is investigated by the use of the H\"uckel Hamiltonian with \ensuremath{\sigma}-bond compressibility. Excess charges are assumed to be stored in conformational defects of the bipolaron type. The Hamiltonian matrix elements represen…
2-lodo-(1) and 2,6(7)-diiodo-tetrathiafulvalenes (2a, 2b) have been synthesized in good yields, by treating the corresponding lithiated intermediates of TTF with perfluorohexyl iodide; the X-ray crystal structures of 1 and 2a have been determined.
The ESR spectra for a series of binuclear trigonal bipyramidal copper complexes show that the SOMO is largely composed of the two equivalent dz2 orbitals on copper; the temperature independence of the ESR parameters shows that this is a relatively strong bond, and since the unpaired electron is antibonding, the σ-bond…
The promotion of oriented calcie crystallization by various polyelectrolytes , in particular their relative efficiency, has been investigated. Gelatin containing polyelectrolytes was found to overcome the compatibility problem between an inert matrix and the water‐soluble polyelectrolytes as sociated with biomineraliz…
Hydrogen uptake in zirconium alloy CANDU (CANada Deuterium Uranium) pressure tubes and other core components is controlled by the rate of transport of atomic/ionic species across the oxide film. The importance of understanding the mechanism of transport stems from the need to predict and control the rate of uptake. Sa…
Prolonged photolysis of aqueous solutions containing [V4O12]4– and MeOH at pH 9 (pH adjusted by use of K2CO3) led to the formation of K5H2[V15O36(CO3)]·1 4.5H2O. A single-crystal X-ray structural analysis of dark green crystals of K5H2[V15O36(CO3)]·14.5H2O [triclinic, space group Pa= 12.361 (4), b= 18.149(5), c= 11.41…
Drying processes are complex because of the non-linearity of physical phenomena and of the distributed parameter character on many levels of consideration. At different scales the relative importance of phenomena will differ. A discussion of the level structure is presented and the concept of “critical grain size” is…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTElectrochemical and chemical preparation of linear .pi.-conjugated poly(quinoline-2,6-diyl) using nickel complexes and electrochemical properties of the polymerNobuo Saito, Takaki Kanbara, Yoshiyuki Nakamura, Takakazu Yamamoto, and Kenji KubotaCite this: Macromolecules 1994,…
Ground-state, fluorescence and triplet-state parameters, together with singlet oxygen quantum yields are presented for two porphyrins with extensive substituents at both the β-pyrrole and meso positions. The relevance of the results to the photodynamic therapy of cancer is discussed.
The isotopic distribution of carbon dioxide desorbed from an MgO surface containing adsorbed 18O-labelled carbon dioxide (C18O2) has been measured by temperature-programmed desorption (TPD), in order to study acid–base pair sites on the surface. Three desorption peaks, differing in both isotopic distribution and tempe…
Catalysis of Diels–Alder reactions by various clay minerals exchanged with a variety of transition metal cations was shown to occur readily at ambient temperatures in a variety of solvents. Nontransition and lanthanide cation-exchanged clays were found to be ineffective. α,β-Unsaturated carbonyl compounds (such as met…