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51.
Avian eggshell matrix proteins were studied by two analytical approaches. Peptide mapping was done by trypsin and pepsin followed by collagenase cleavage; analyses were carried out by capillary electrophoresis and reversed-phase high-performance liquid chromatography (HPLC). Comparison of peptide maps obtained by both methods revealed a complex mixture of peptides in the insoluble layers of the eggshell; it was concluded that there are at least three different insoluble protein/peptide layers in the avian eggshell (cuticle, palisade, and mammillary layer). Partial characterization of peptides in each layer was made by HPLC-mass spectrometry analysis. There is an evidence that the eggshell insoluble proteins contain species susceptible to collagenase cleavage, however, the sequences split by this enzyme probably are not those typical for the main triple-helical core of collagenous proteins. It is proposed that the action of collagenase upon eggshell proteins is caused by the side effect of collagenase described previously with synthetic peptides. Some of the proteins present are probably glycosylated. Fatty acid content in the insoluble eggshell layers (after decalcification) was in the range of 2-4% (which reflected both lipid and lipoproteins bound fatty acids). Porphyrin pigments are dominant in the cuticle layer. 相似文献
52.
Bruno Crociani Umberto Belluco Pierluigi Sandrini 《Journal of organometallic chemistry》1979,177(2):385-401
The reactions of the organometallic 1,4-diazabutadienes, RN=C(R′)C(Me)=NR″ [R = R″ = p-C6H4OMe, R′ = trans-PdCl(PPh3)2 (DAB); R = p-C6H4OMe, R″ = Me, R′ = trans-PdCl(PPh3)2 (DABI; R = R″ = p-C6H4OMe, R′ = Pd(dmtc)-(PPh3), dmtc = dimethyldithiocarbamate (DABII); R = R″ = p-C6H4OMe, R′ = PdCl(diphos), diphos = 1,2-bis(diphenylphosphino)ethane (DABIII)] with [RhCl(COD)]2 (COD = 1,5-cyclooctadiene, Pd/Rh ratio = ) depend on the nature of the ancillary ligands at the Pd atom in group R′. In the reactions with DAB and DABI transfer of one PPh3 ligand from Pd to Rh occurs yielding [RhCl(COD)(PPh3)] and the new binuclear complexes [Rh(COD) {RN=C(R?)-C(Me)=NR″}], in which the diazabutadiene moiety acts as a chelating bidentate ligand. Exchange of ligands between the two different metallic centers also occurs in the reaction with DABII. In this case, the migration of the bidentate dmtc anion yields [Rh(COD)Pdmtc] and [Rh(COD) {RN=C(R?)C(Me)=NR″}]. In contrast, the reaction with DABIII leads to the ionic product [Rh(COD)- (DABIII)][RhCl2(COD)], with no transfer of ligands. The cationic complex [Rh(COD)(DABIII)]+ can be isolated as the perchlorate salt from the same reaction (Pd/Rh ratio = 1/1) in the presence of an excess of NaClO4. In all the binuclear complexes the coordinated 1,5-cyclooctadiene can be readily displaced by carbon monoxide to give the corresponding dicarbonyl derivatives. The reaction of [RhCl(CO)2]2 with DAB and/or DABI yields trinuclear complexes of the type [RhCl(CO)2]2(DAB), in which the diazabutadiene group acts as a bridging bidentate ligand. Some reactions of the organic diazabutadiene RN=C(Me)C(Me)=NR (R = p-C6H4OMe) are also reported for comparison. 相似文献
53.
Bruno Gabutti 《Numerische Mathematik》1984,43(3):439-461
Summary The Euler-Knopp transformation and a recently considered transformation, effective for entire function of order 1, are applied to series involving completely monotonic coefficients. Some properties of the resulting series are analyzed; these include uniform convergence with respect to the index, a priori and a posteriori estimates of the remainder. For the latter transformation a compact recursive algorithm is established which enables one to make effective use of the transformation. To illustrate the effectiveness of the transformations three applications, with examples, are included. 相似文献
54.
Bruno Gabutti 《Zeitschrift für Angewandte Mathematik und Physik (ZAMP)》1984,35(3):265-281
Summary Considerf+
ff+ (1–f2)+
f=0 together with the boundary conditionsf(0)=f(0)=0,f ()=1. If=–1,>0, arbitrary there is at least one solution which satisfies 0<f<1 on (0, ). By the additional conditionf>0 on (0, ) or, alternately 0<1, the uniqueness of the solution is demonstrated.If=1,<0, arbitrary the existence of solutions for which –1<f<0 in some initial interval (0,t) and satisfying generallyf>1 is established. In both problems, bounds forf (0) and qualitative behavior of the solutions are shown.
Sommario Si consideri il problema definito dall'equazionef+ f f+ (1–f2)+ f=0 e dalle condizioni al contornof(0)=f (0)=0,f()=1. Assumendo=–1,>0, arbitrario si dimostra che esiste almeno una soluzione che soddisfa 0<f<1 nell'intervallo (0, ). Se in aggiunta si ipotizzaf>0 in (0, ), oppure 0<=1, l'unicità délia soluzione è assicurata.Successivamente si considéra il problema di valori al contorno con=1,<0, arbitrario. In questo caso esiste un'intera classe di soluzioni che soddisfano –1<f<0 in un intorno dell'origine e tali chef>1, in generale.Di detti problemi viene studiato il comportamento délle soluzioni e vengono determinate dalle maggiorazioni e minorazioni del valoref(0).相似文献
55.
G. Bruno P. Capezzuto G. Cicala F. Cramarossa 《Plasma Chemistry and Plasma Processing》1986,6(2):109-125
Plasma-chemical reduction of SiCl4 in mixtures with H2 and Ar has been studied by optical emission spectroscopy (OES) and laser interferometry techniques. It has been found that the Ar:H2 ratio strongly affects the plasma composition as well as the deposition (r
D) and etch (r
E) rates of Si: H, Cl films and that the electron impact dissociation is the most important channel for the production of SiClx species, which are the precursors of the film growth. Chemisorption of SiClx and the reactive surface reaction SiClx+H–SiCl(x–1)0+HCl are important steps in the deposition process. The suggested deposition model givesr
D [SiClx][H], in agreement with the experimental data. Etching of Si: H, Cl films occurs at high Ar: H2 ratio when Cl atoms in the gas phase become appreciable and increases with increasing Cl concentration. The etch rate is controlled by the Cl atom chemisorption step. 相似文献
56.
Bruno Jean Georges Bokias Lay-Theng Lee Ilias Iliopoulos Bernard Cabane 《Colloid and polymer science》2002,280(10):908-914
The structures of aqueous copolymer solutions have been examined through small angle neutron scattering. The copolymers contained mostly N-isopropylacrylamide (NIPAM) monomers. Poly (NIPAM) solutions have a lower critical solution temperature (LCST), above which the macromolecules separate from water. A small fraction of ionizable N,N-[(dimethylamino) propyl] methacrylamide (MADAP) monomers was introduced into the macromolecules. This had dramatic consequences on the solution behavior at temperatures above the LCST of PNIPAM, where phase separation would have been expected for the homopolymer. When all MADAP monomers were ionized, it was found that the solutions resisted the phase separation. At short spatial scales, the chains were collapsed but at large scales they formed branched aggregates that did not separate out of water. When only half of the MADAP monomers are ionized, the electrical charges were able to redistribute themselves along the chains. In this case, the rise in temperature caused a microphase separation where the electrical charges were relocated on a fraction of the chains that remained in solution.The other chains (or section of chains) formed large nodules of a polymer rich phase. 相似文献
57.
Zhdankin VV Maydanovych O Herschbach J Bruno J Matveeva ED Zefirov NS 《The Journal of organic chemistry》2003,68(3):1018-1023
The preparation and chemistry of novel phosphoranyl-derived lambda(3)-iodanes is reported. The phosphoranyl-derived phenyliodonium sulfonates were prepared in good yields by the reaction of stabilized phosphonium ylides [1-triphenylphosphoranylidene-2-propanone, methyl(triphenylphosphoranylidene)acetate, (triphenylphosphoranylidene)acetaldehyde, and (triphenylphosphoranylidene)acetonitrile] with the pyridinium complex of iodobenzene ditriflate or with [hydroxy(tosyloxy)iodo]benzene under mild conditions. These compounds represent a potentially useful class of reagents that combine in one molecule synthetic advantages of a phosphonium ylide and an iodonium salt. Specifically, phosphorane-derived phenyliodonium tosylates can react with soft nucleophiles, such as iodide, bromide, benzenesulfinate, and thiophenolate anions, with a selective formation of the respective alpha-functionalized phosphonium ylides, which can be further converted to alkenes by the Wittig reaction with benzaldehyde. The phosphoranyl-derived benziodoxoles can be prepared by the reaction of 1-acetoxybenziodoxole with stabilized phosphonium ylides. An unusual ligand exchange on the iodine(III) center resulting in the substitution of a carbon ligand with an oxygen ligand was observed in the reaction of these compounds with strong acids. 相似文献
58.
The photolysis and thermolysis of the Cyclopropyl silyl ketones 3, 4 , and 5 are described. On n,π* excitation, the silyl ketones 3 and 4 undergo a Norrish-type-II reaction involving γ-H abstraction, cyclopropyl ring cleavage followed by retro-enolization to the acylsilanes 6 and (E/Z)- 12 , respectively. As a common product of 3 and 4 , the dihydrofuran 7 is formed via the alternative C(α)-C(β) cleavage of the cyclopropyl moiety. Compounds 6 , 7 , and (E/Z)- 12 are new types of acylsilane photoproducts. The irradiation of acylsilane 5 gave the analogous dihydrofuran 15 as the only product. On photolysis of 3 and 4 , products 8A + B and 13A + B , derived from a siloxy carbene intermediate, were found as well. On thermolysis of 3 and 4 , the acylsilanes 6 (80%), and (E)- 12 (33%) and (Z)- 12 (34%), respectively, are formed as the only products. Their formation may occur via a [1, 5] sigmatropic H-shift. The thermolysis of 5 gave the diene 16 whose formation can be explained by insertion of a siloxycarbene into the neighboring cyclopropane leading to the cyclobutene 28 as thermally unstable intermediate. 相似文献
59.
Two sufficient criteria for the convergence of the Rayleigh-Ritz Method (RRM) with respect to the eigenvalues (E-convergence) of non-relativistic electronic Hamiltonians of molecules are discussed and compared. Moreover, a necessary and sufficient criterion is given. By example (Sect. 9) it is shown that the L
2-completeness of the basis is not sufficient to guarantee E-convergence. The convergence of the wave functions in different norms (-convergence) is also investigated. In particular, sufficient conditions for the one-particle basis functions (orbitals) are given, such that a CI calculation in this basis is both E- and -convergent. 相似文献
60.
Georg Süss-Fink Bruno Therrien Mathieu Tschan Thomas R Ward Gabor Laurenczy 《Journal of organometallic chemistry》2004,689(8):1362-1369
By checking the chemistry underlying the concept of “supramolecular cluster catalysis” we identified two major errors in our publications related to this topic, which are essentially due to contamination problems. (1) The conversion of the “closed” cluster cation [H3Ru3(C6H6)(C6Me6)2(O)]+ (1) into the “open” cluster cation [H2Ru3(C6H6)(C6Me6)2(O)(OH)]+ (2), which we had ascribed to a reaction with water in the presence of ethylbenzene is simply an oxidation reaction which occurs in the presence of air. (2) The higher catalytic activity observed with ethylbenzene, which we had erroneously attributed to the “open” cluster cation [H2Ru3(C6H6)(C6Me6)2(O)(OH)]+ (2), was due to the formation of RuO2 · nH2O, caused by a hydroperoxide contamination present in ethylbenzene. 相似文献