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51.
52.
The Mössbauer spectra of iron (III) bis and tris dithiocarbamates containing the piperidylradical have been investigated at various temperatures. The tris chelate shows a quadrupole splitting decreasing when the sample is warmed up which indicates the presence of a Boltzmann spin equilibrium. The bis chelate yields a temperature-independent quadrupole splitting due to the lattice contribution.Work sponsored in part by G.N.S.M. and in part by C.N.R. 相似文献
53.
54.
Cholesterol oxidation in commercial meat-based homogenized and freeze-dried baby foods was examined. The 7 major products of this reaction were determined by gas chromatography coupled with mass spectrometry (GC-MS). As far as single cholesterol oxidation products (COP) are concerned, 7-ketocholesterol was the major product of direct cholesterol oxidation in the 2 groups of analyzed samples, and this study confirmed that it is a useful marker of the whole cholesterol oxidation process. Nevertheless, the amounts of cholesterol-5beta,6beta-epoxide were often similar to and sometimes higher than the amounts of 7-ketocholesterol, thus showing a strong development of both direct and indirect cholesterol oxidation pathways. Total COP content was significantly higher in freeze-dried than in homogenized products. Moreover, in freeze-dried samples, the COP content per serving was quite variable and, in 2 samples, it was close to or even higher than 500 microg. The greater development of cholesterol oxidation in the freeze-dried samples was confirmed by their highest total COP/cholesterol percent ratios. A constant correlation between the fatty acid composition and the development of cholesterol oxidation was not found, although a positive correlation between unsaturated fatty acid content and total COP content occasionally exists in samples of the same brand. 相似文献
55.
Let W be a finite Coxeter group generated by real reflections in a complex vector space. We compute the integral cohomology of the Milnor fibre of the discriminant bundle , together with the action of the monodromy, for the whole list of exceptional groups. Here Δ is the map induced by the square of the polynomial defining the arrangement of reflection hyperplanes of W. The computation is equivalent to that of the cohomology, with suitable local coefficients, of the corresponding Artin group. These computations complete, for the exceptional cases, those performed by De Concini et al. for rational coefficients. To cite this article: F. Callegaro, M. Salvetti, C. R. Acad. Sci. Paris, Ser. I 339 (2004). 相似文献
56.
Filippo Bracci 《Transactions of the American Mathematical Society》2003,355(6):2569-2584
Let be the unit disc of and let be such that . For 1$">, let . We study the behavior of on . In particular, we prove that . As a consequence, besides conditions for , we prove a conjecture of C. Cowen in case and are univalent mappings.
57.
Filippo Gazzola Hans-Christoph Grunau Enzo Mitidieri 《Transactions of the American Mathematical Society》2004,356(6):2149-2168
We show that the classical Hardy inequalities with optimal constants in the Sobolev spaces and in higher-order Sobolev spaces on a bounded domain can be refined by adding remainder terms which involve norms. In the higher-order case further norms with lower-order singular weights arise. The case being more involved requires a different technique and is developed only in the space .
58.
We investigate entire radial solutions of the semilinear biharmonic equation Δ2u=λexp(u) in Rn, n?5, λ>0 being a parameter. We show that singular radial solutions of the corresponding Dirichlet problem in the unit ball cannot be extended as solutions of the equation to the whole of Rn. In particular, they cannot be expanded as power series in the natural variable s=log|x|. Next, we prove the existence of infinitely many entire regular radial solutions. They all diverge to −∞ as |x|→∞ and we specify their asymptotic behaviour. As in the case with power-type nonlinearities [F. Gazzola, H.-Ch. Grunau, Radial entire solutions for supercritical biharmonic equations, Math. Ann. 334 (2006) 905-936], the entire singular solution x?−4log|x| plays the role of a separatrix in the bifurcation picture. Finally, a technique for the computer assisted study of a broad class of equations is developed. It is applied to obtain a computer assisted proof of the underlying dynamical behaviour for the bifurcation diagram of a corresponding autonomous system of ODEs, in the case n=5. 相似文献
59.
Marcantonio Bragadin Giuseppe Scarponi Gabriele Capodaglio Franco Ossola Vito Bartocci Filippo Pucciarelli 《Molecular Crystals and Liquid Crystals》2013,570(1-4):345-348
New photosensitive materials can be obtained by electrochemical oxidation of thiocyanate and selenocyanate salts. Using (K,Na)SCN eutectic melt, the formation of an electrodic deposit, with photoelectrochemical properties, has already been reported by us. To improve the photoelectrochemical characteristics of the deposit, futher investigations were carried out in the following sistems: selenocyanate ammoniate, KSCH-Acetamide eutectic mixture and KSCN ethylene carbonate solution:. Attempts to obtain a massive deposit in the ammoniate solution were unsuccessful due to ammonia oxidation. Measurements performed on the other KSCN systems show that temperature is a parameter of remarkable importance. In fact, lowering the temperature one obtains a decrease on formation of parathiocyanogen on behalf of the polytrithiocyanogen, the species that gives rise to the photoeffect. 相似文献
60.
Abbotto A Sauvage F Barolo C De Angelis F Fantacci S Graetzel M Manfredi N Marinzi C Nazeeruddin MK 《Dalton transactions (Cambridge, England : 2003)》2011,40(1):234-242
The first example of a heteroarylvinylene π-conjugated quaterpyridine Ru(II) sensitizer (N1044) was synthesized and used in dye-sensitized solar cells; the dye has an effective panchromatic absorption band, covering the entire visible spectrum up to the NIR region, and superior electrochemical characteristics (HOMO/LUMO and bandgap energies) with respect to previous representative Ru(II) bi- and quaterpyridine sensitizers. A record IPCE curve ranging from 360 to 920 nm has been measured with a maximum of 65% at 646 nm and still 33% efficiency at 800 nm; this leads to substantially increased photocurrent (19.2 mA cm(-2)) when compared to the prototype N719 Ru(II) sensitizer. 相似文献