Materials Literature
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Ab initio calculations have been carried out on 6-hydroxy-1-formylfulvene(HFF) to study (a) the ground-state molecular structure and relative stability of conformers, (b) the strength and main features of the intramolecular hydrogen bond, including harmonic vibrational frequencies and proton tunnelling, (c) hydrogen-b…
Abstract Epitaxial crystallization of high‐density polyethylene (HDPE), linear low‐density polyethylene (LLDPE) and low‐density polyethylene (LDPE) in the epitaxial system with highly oriented isotactic poly(propylene) (iPP) has been investigated by electron microscopy. The results obtained by bright field electron mi…
The problem of matching thermoelectric coolers and semiconductor lasers with respect to heat flow densities and electrical currents is discussed. It is shown that the solution of this problem is accomplished by the reduction of thermoelement dimensions to the submillimeter level. Assembled with extruded thermoelectric…
The structure of alkaline earth vanadate glasses of the compositions, xMO⋅(100-x)V2O5 (M=Mg, Ca, Sr, Ba, x=30, 40, 45, 50, 55), has been investigated by means of IR spectroscopy with reference to various crystalline alkaline earth vanadates structurally known. It is found that the structure of alkaline earth vanadate…
Recent plate impact experiments on glass specimens have apparently resulted in the generation of failure waves under uniaxial compression. Herein similar experiments are reported and interpreted for an aluminosilicate glass as a means for examining possible explanations of the observed behavior. This investigation bea…
Wegen des Raumbedarfs der tert ‐Butylgruppen weicht die Reaktivität des neuartigen Porphyrins 1 mit nichtplanarem makrocyclischem Grundgerüst von der aller bekannten Porphyrine ab. So führt längere Behandlung von 1 mit HClO 4 /MeOH zur Bildung des 5,15‐Dihydroporphyrins (“Porphodimethens”) 2 . magnified image
Isotropic and frozen-solution ESR spectra in CH2Cl2–ClCH2CH2Cl have been recorded for the five-co-ordinate, formally cobalt(IV) complexes [Co(S2C2R2)2L][R = CN, L = PEt3; R = CF3or Ph, L = PPh3or P(OPh)3; R = C6H4Me-4, L = PPh3or PEt3; R = C6H4OMe-4, L = PPh3]. The spectra can be described by approximately axial g and…
Flächenverknüpfte Tetraeder , die in Form einer Helix angeordnet sind (Idealform unten dargestellt), kennzeichnen die Struktur des Iodocuprats 1 , das aus Ph 4 Pi, I 2 und Cu erhalten wurde. Von den bei Raumtemperatur identifizierten fünf Cu‐Lagen sind bei tiefer Temperatur nur noch drei (langsames Abkühlen) oder vier…
The 3d electrons of chromium(III) and the unpaired electron of the nitroxide radical interact ferro- and antiferro-magnetically in chloro-meso-tetraphenylporphyrinatochromium(III) ligated with 3- and 4-(N-oxy-N-tert-butylamino)pyridines to produce quintet and triplet ground states, respectively.
Silica supported Ru–Cu bimetallic catalysts have been studied by FTIR Spectroscopy. Experiments have been carried out on two series of samples prepared from RuCl3 and Ru(NO)(NO3)3. The systems studied contained a total amount of metal of ca. 2 wt.%. On the monometallic Ru/SiO2 samples, adsorption of CO led to an asyme…
To date little work has been done on powder metallurgical duplex austenitic-ferritic stainless steels. In the present work the manufacture of this type of steel from prealloyed and mixed powders is studied together with the possibility of obtaining duplex compositions of other than 50% ferrite-50% austenite. Mechanica…
The dielectric properties of inhomogeneous media constituted by a glassy semicrystalline polymer (polypropylene) impregnated by an aromatic fluid (monodibenzyltoluene) are studied. The measured permittivity is compared to various forms of mixture equations. The closest agreement is obtained with the Lichteneker’s loga…
Abstract Acrylamide and acrylonitrile were polymerized with water‐soluble organic reducing compounds containing hydroxy groups such as methyl cellulose (MC), methyl hydroxy‐propyl cellulose (MHPC) and poly(ethylene glycol)s (PEG) in the presence of Ce(IV) in order to produce graft/block copolymers. The effect of ceriu…
The /spl delta/M curves predicted by the vector Preisach model are analyzed and proved to always be negative. A mean interaction field parallel to the magnetization is added to the model so as to reproduce the positive /spl delta/M curve of barium ferrite particulate media. By using this model in self consistent field…
The structure of a vehicle surrounding the occupant compartment is designed to crush in an accident in order to limit the forces that are transmitted to its occupants. Crush initiators are stress concentrations that are incorporated into automobile frame members to ensure a stable collapse process and to limit peak lo…
Vacuum brazing of A5000 (Al-Mg) series and A6000 (Al-Mg-Si) series aluminum alloys are considerably difficult because of their rather high magnesium contents. For the purpose of sound and high strength brazing of these materials, a series of Al-Ge-Si-Mg system based filler metales was developed by the authors. Evaluat…
The crystallization of high purity amorphous polymer-derived Si3N4 fiber, which was heat-treated with and without BN powders, was investigated. In the case without BN powder, the crystallization proceeds by vapor phase growth mechanism through SiO gas. The activation energy of 602kJ/mol was calculated. In the case wit…
Silicon carbide ceramics are candidate materials for use in aggressive environments, including those where aqueous acids are present. Standard corrosion testing methods such as immersion testing are not always sufficiently sensitive for these ceramics owing to the very low, almost unobservable, corrosion rates encount…
In this investigation a stable high manganese austenitic steel, 0.45C-17Mn-2.8Al, has been studied for hydrogen embrittlement using cathodically precharged specimens. Tensile testing of axisymmetric and plane strain specimens precharged with hydrogen show an appreciable loss of 8-10% reduction in area (RA) whereas the…
The crystal structure of a unique cholic acid inclusion compound with acetone and water guests exhibiting extensive hydrogen bonding is reported and the phases formed during decomposition identified by thermal analysis and X-ray powder diffraction.