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Ein effizienter bifunktioneller Katalysator für die Titelreaktion ist Cobalttetra(hydrochinon)porphyrin 1 . Die oxidierte Form von 1 (rechts schematisch dargestellt. R = Hydrochinon) hat eine Einheit für die Wechselwirkung mit molekularem O 2 , eine andere für die Wechselwirkung mit dem Pd‐Katalysator. So können Elekt…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTCorrelation of CrOCr .pi.-bonding strength with .pi.-donor effectiveness of bridging and nonbridging ligands in (tris(2-pyridylmethyl)amine)chromium(III) dimersThomas F. Tekut, Charles J. O'Connor, and Robert A. HolwerdaCite this: Inorg. Chem. 1993, 32, 3, 324–328Publication…
The anisotropic thermal expansion parameters a(T), b(T) and c(T) of some RECu 2 , intermetallics (RE=Y, Er, Nd) has been measured in the temperature range from 400 K down to 4.2 K using X-ray powder diffraction. The influence of the crystal field on the thermal expansion in ErCu 2 and NdCu 2 has been determined by com…
A model for the shape and motion of disclination loops observed in thermotropic small molar mass and polymeric nematic liquid crystals in the presence of steady rectilinear shear and oscillatory rectilinear shear flow is presented. In steady rectilinear simple shear, disclination loops elongate and tumble, before retr…
Transgranular stress‐corrosion cracking without copper oxidation has been demonstrated in α‐brass, confirming the findings of Bertocci, Thomas, and Pugh (1984), Cracks continued to propagate in monocrystals at potentials as low as −40 mV vs. a copper reference electrode in solutions. Residual Cu(II) in these solutions…
Corrosion and its control of mild steel in drilling muds containing 3.2 g/L H2S have been studied with the wheel test method to increase drill pipe service life. The high corrosion rate is attributed to the presence of H2S. The corrosion product was shown to be Fe9S8 by x-ray diffraction and exhibited very poor protec…
Abstract High molecular weight aromatic polyetherketone (PEK) was found to react with 4,4′‐difluorobenzophenone (DFB) in the presence of potassium carbonate in benzophenone or diphenyl sulfone at 300°C, yielding low molecular weight PEK with fluorophenyl end groups, while neither polyetheretherketone (PEEK) nor poly‐t…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTPolyisobutylene-toughened poly(methyl methacrylate). 1. Synthesis, characterization, and tensile properties of PMMA-l-PIB networksJoseph P. Kennedy and G. Caywood RichardCite this: Macromolecules 1993, 26, 4, 567–571Publication Date (Print):February 1, 1993Publication Histor…
The early-to-late stage of spinodal decomposition in a critical mixture of polystyrene and polymethylphenylsiloxane was studied by time-resolved light scattering over 1.8k21.1 \ensuremath{\mu}${\mathrm{m}}^{\mathrm{\ensuremath{-}}1}$ and 0t502 h, with k and t being the wave number and the elapsed time after temperatur…
Abstract Durch Umsetzungen der Alkalimetallcarbonate mit Chrom und dem entsprechenden Chalkogen in der Schmelze konnten die Verbindungen RbCr 3 S 5 , K 3 Cr 11 S 18 , RbCr 5 Se 8 und CsCr 5 Se 8 als gut ausgebildete Kristalle erhalten werden. Die Verbindungen kristallisieren monoklin im Raumgruppentyp C2/m (RbCr 3 S 5…
Two planktonic species of diatoms, Chaetoceros bacteriastroides and C. seychellarus , have been studied by light and electron microscopy. Important features that may be used as taxonomic characters are described. A new subgenus, Bacteriastroidea, is proposed to include C. bacteriastroides, because of its unique charac…
A 2 × 2 propagation-matrix formalism for finding the obliquely propagating electromagnetic fields in layered inhomogeneous uniaxial structures is presented. The 2 × 2 propagation matrix was produced by our generalized geometrical-optics approximation method. A 2 × 1 field vector for the transverse electric field is de…
Kaempferol 3-O-[alpha-L-rhamnopyranosyl (1-->6)-beta-D-glucopyranoside] and kaempferol 3-O-[beta-D-glucopyranoside] were isolated from the leaves of Hedyosmum bonplandianum H.B.K. (Chloranthaceae), which is used in Colombian folk medicine as an analgesic. The n-butanol extract and the glycosyl flavonoids isolated exhi…
Abstract Bisupported catalysts for olefin polymerization were prepared by mixing a butyl alcoholate solution of MgCI 2 with pretreated SiO 2 in heptane, and further treating with TiCI 4 solution. The silica pretreating conditions and their effects on the composition of the catalysts were studied. The interaction mecha…
Scanning electron microscopy has been used to observe the details of the apical structure of the theca in 46 species belonging to 10 genera (Boreadinium, Diplopsalis, Diplopsalopsis, Dissodium, Lebouraia, Oblea, Peridiniopsis, Peridinium, Protoperidinium, Zygabikodinium) in the family Peridiniaceae (Dinophyceae). The…
ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTElectrochemical and spectroelectrochemical characterization of (5,10,15,20-tetrakis(1-methyl-4-pyridyl)porphinato)manganese(III) chloride, [(TMpyP)MnIIICl]4+(Cl-)4, in N,N-dimethylformamideEric Van Caemelbecke, Wlodzimierz Kutner, and Karl M. KadishCite this: Inorg. Chem. 19…
The synthesis and mesomorphic behavior of 3,5-bis-(p-n-alkoxyphenyl)isoxazole (series I) and 3,5-bis-(p-n-alkoxyphenyl)pyrazole (series II) are reported for the number of carbon atoms (n) in the alkoxy chains varying from three to eight. Series I shows an enantiotropic nematic phase for all n and an enantiotropic smec…
Measurements of tilt bias angles of a nematic liquid crystal were carried out, by using several alkylene polyimides synthesized from 3,3′,4,4′-biphenyltetracarboxylic dianhydrides and diamines with different chain lengths as alignment layers. The tilt bias angle dependence on the alkylene chain length of polyimides sh…
The mesogenic behaviour of a series of thirty-one 1-alkyl-4-(or 2-)alkylpyridinium salts and of a homologous series of four 1-methyl-4-n-alkoxycarbonylpyridinium iodides is described. The occurrence and stability range of the thermotropic phases depend dramatically on the structure of the surfactants. Mesophases are o…
This paper considers the dynamics of a gas bubble in response to either a pressure pulse or a pressure step at t = 0, both in the presence and absence of a mean flow. Our work utilizes small-deformation, domain perturbation analysis carried to second and higher order in the amplitude of deformation, ε. In the absence…