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ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTNew five- and six-coordinate imidazole and imidazolate complexes of ferric tetraphenylporphyrinRobert Quinn, Mario Nappa, and Joan S. ValentineCite this: J. Am. Chem. Soc. 1982, 104, 9, 2588–2595Publication Date (Print):May 1, 1982Publication History Published online1 May 20…
Type IV collagen was isolated in high yield from bovine kidney cortex. The protein revealed Mr = 380,000 and contained, in a 2:1 ratio, two different disulfide-linked polypeptide chains, C-1 and D-1 (Mr = 125,000). Carboxymethyl-cellulose chromatography before and after reduction proved that the two polypeptide chains…
Metal-binding properties of calmodulin have been studied by using trivalent lanthanide ions as analogs of Ca2+. In agreement with a report published as this work was in progress [Kilhoffer, M.-C., Demaille, J. G., and Gerald, D. (1980) FEBS Lett. 116, 269-272] we found that sites I and II are the high-affinity sites,…
Abstract It is frequently observed that the gel effect in vinyl polymerizations decreases in intensity at about the 50‐70% conversion level. This is apparent in both rate and molecular weight data. It is postulated that there should be a limitation on the decrease in the termination rate constant to explain this effec…
A molecular dynamics study of the thermodynamic, structural and dynamical properties of a model silicon dioxide glass is described. The system consists of 3000 ions in a cubic volume. The results of the present simulation are compared with the results of our earlier simulation of a small system containing only 375 ion…
The Gibbs energies of formation of three compounds in the , , and —have been determined from potentiometric measurements on reversible solid‐state galvanic cells and in the temperature range 850–1375 K. The results are discussed in the light of reported phase diagrams for the system. The partial pressures of different…
This paper presents the theoretical aspects and the experimental results of a study carried out at Ecole Polytechnique de Montrdal on wetting processes on a contaminated insulator surface. Four wetting processes for clean-fog test using the precontamination method are distinguished, namely, collision of water droplets…
The EPR spectra of the five-coordinated complexes [CoX(Me6tren)]Y (Me6tren = tris[2-(dimethylamino)ethyl]amine; X = C1, Br, I; Y = C1, Br, I, BPh,) and [CoX(np3)]Y (np3 = tris[2-(diphenylphosphino)ethyl]amine; X = CI, Br, I; Y = PFs, BPh4) have been recorded. The Me6tren complexes were found to yield g,, = 2 and g, =…
The preparation of the new ligand 1,4,7,10-tetramethyl-1,4,7,10-tetraazacyclododecane, (-N(Me)-(CH2)2-)4 (= L), and the complexes [NiL] (ClO4)2, [NiL(OCHNMe2)] (ClO4)2, [NiLN3] ClO4, [CuL] (ClO4)2, and [NiY] (ClO4)2, where Y = (-N(Me)(CH2)2N(Me)(CH2)3-)2, 1,4,8,11-tetra-methyl-1,4,8,11-tetraazacyclotetradecane, are de…
Abstract The exchange interactions in four kinds of verdazyl crystals, 2,4,6-triphenylverdazyl (TPV), 2,4,6-triphenyl-3-methylverdazyl (MeTPV), 2,4,6-tri-p-tolylverdazyl (TTV), and 2,6-di-p-tolyl-4-phenylverdazyl (DTPV), have been studied by means of McConnell’s spin density Hamiltonian. The calculated exchange parame…
The rate of dissolution of β‐Si 3 N 4 into an Mg‐Si‐O‐N glass was measured by working with a composition in the ternary system Si 3 N 4 ‐SiO 2 ‐MgO such that Si 2 N 2 O rather than β‐Si 3 N 4 was the equilibrium phase. Dissolution was driven by the chemical reaction Si 3 N 4 (c)+SiO 2 ( l )→Si 2 N 2 O(c). Analysis of…
The structure of the MgGDP complex at the active site of elongation factor (EF-Tu) has been investigated by using phosphorothioate analogs of GDP in the absence and presence of various metal ions, electron paramagnetic resonance (EPR) and nuclear magnetic resonance (NMR) measurements. The high stereoselectivity of EF-…
Conducting polymer is prepared from teflon by treatment with a THF solution of alkali-naphthalide. The electrical conductivity of this film is of the order 10 -5 -10 -4 (Ω·cm) -1 which is higher than that of teflon by more than ten orders of magnitude and comparable with that of trans (CH) x . The observed small activ…
The theoretical model underlying a two-strand spinning system is given. It is shown that, for an idealized model, the equilibrium twist in the strands is dependent upon a torsion balance existing between an individual strand above the convergence point and the strand as it lies in th plied structure. As a consequence,…
Abstract The effects of thermal oxidation on the‐ molecular structure and on the morphology of a series of high‐density polyethylene pipes have been studied “as received” or after service. The existence of a 40 to 170 μm thick oxidation skin was established, the structure and morphology of which were characterized by…
Finite difference and finite element methods are investigated as applied to Laplace and Poisson linear equations in two dimensions. The comparative analysis concentrates on first-order square, rectangular, triangular and polar algorithms which are characteristic to each method. The results are found to be independent…
The chemical identification of chlorophyllide (E458F674) (Belanger, F. C., and Rebeiz, C. A. (1980) Plant Sci. Lett. 18, 343-350) has been confirmed by chemical derivatization coupled to spectrofluorometric, spectrophotometric, and chromatographic analysis. Chlorophyllide (E458F674) and its demetallated analog were co…
BIS[(1-PHENYL-1-CYCLOPROPYL)CARBONYL] PEROXIDE 1679 such a conformation unfavourable. The observed conformation is 21 o from the perpendicular geometry. It appears, therefore, that the observed geometry is a consequence of a balance between two opposing constraints: (i) maximization of orbital overlap between the n sy…
Abstract The degradation of isotactic polypropylene in the range 390–465°C was studied using factor‐jump thermogravimetry. The degradations were carried out in vacuum and at pressures of 5 and 800 mm Hg of N 2 , flowing at 100–400 standard mL/s. At 800 mm Hg this corresponds to linear rates of 1–4 mm/s. In vacuum bubb…
The complete reduction of a fourth-rank Cartesian tensor into parts wich are irreducible under the three-dimensional rotation group is presented. Results are given for the general case of a tensor without index permutational symmetry, and also for tensors with specific index symmetry properties. Applications in the re…