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101.
If Au = - div(a(x, Du)) is a monotone operator defined on the Sobolev space W1,P(R
n, 1 < p < + , with a(x,0) = 0 for a.e. x Rn, the capacity C_A(E,F) relative to A can be defined for every pair (E,F) of bounded sets in Rn with E F. The main properties of the set function CA(E,F) are investigated. In particular it is proved that CA(E,F) is increasing and countably subadditive with respect to E, decreasing with respect to F, and continuous, in a suitable sense, with respect to E and F. 相似文献
102.
Gianni Zotti Sandro Zecchin Barbara Vercelli Anna Berlin Sara Grimoldi Renzo Bertoncello Laura Milanese 《Journal of Electroanalytical Chemistry》2005,580(2):330-339
Self-assembly (SA) of polyviologens with linear alkyl spacers PVn (n = 3–10) on sulfonate-primed gold and ITO electrode surfaces has been investigated by CV, QCM, XPS and AFM. The polymers form stable and relatively dense monolayers even from 10−4 M PVn concentration. The viologen surface density is decreased as n is increased but for n = 10 and on alkylsulfonate-primed surfaces a strong adsorption takes place, with decreased redox potential and very narrow cyclic voltammogram of the absorbed layer due to organized structures on the surface.Stable and regular electrostatically self-assembled (ESA) multilayers are built on sulfonate-primed surfaces with PV3 and polysulfonates. From XPS analysis, the composition of the PVn/polysulfonate multilayers corresponds to a 1:1 ratio of polyanion and polycation charges, i.e., no extra non-polymeric ion is present, independently from the alkane chain length. The rate of electron transfer within the multilayers (diffusion coefficient = ca. 10−9 cm2 s−1) is higher than for analogous bulk materials. 相似文献
103.
Gianni Podda Antonio Maccioni Luciana Corda Enrico Vecchi Sergio Daolio Pietro Traldi 《Journal of heterocyclic chemistry》1985,22(1):17-20
The electron impact mass spectrometric behaviour of some new diastereoisomeric macrocycles containing diglycolyl moiety as subcyclic unit is reported and discussed in detail with the aid of linked scans, exact mass measurements and collisionally activated decomposition mass analyzed ion kinetic energy spectra. 相似文献
104.
Leonardo Bonsignore Anna Maria Fadda Giuseppe Loy Antonio Maccioni Gianni Podda 《Journal of heterocyclic chemistry》1983,20(3):703-707
The cleavage reaction of some 1,3-benzodioxole derivatives with magnesium bromide and acetic anhydride has been studied. The reactions have been carried out in acetonitrile solution at room temperature. In all of the 1,3-benzodioxoles studied, the opening of the heterocyclic ring with formation of bromides, alkenes and their corresponding products of hydrolysis have been observed. The competitive electrophilic substitution on the benzene ring was very limited and was insignificant when a large excess of the cleavage reagent was used. The structures of newly prepared compounds have been determined by elemental analysis, spectroscopic data and comparison with authentic samples. 相似文献
105.
Akbayeva DN Gonsalvi L Oberhauser W Peruzzini M Vizza F Brüggeller P Romerosa A Sava G Bergamo A 《Chemical communications (Cambridge, England)》2003,(2):264-265
The new water soluble ruthenium complexes [(C5R5)RuCl(PTA)2] (R = H, Me; PTA = 1,3,5-triaza-7-phosphaadamantane) were synthesised and characterised. Their evaluation as regioselective catalysts for hydrogenation of unsaturated ketones in aqueous biphasic conditions and as cytotoxic agents towards the TS/A adenocarcinoma cell line is briefly presented. 相似文献
106.
The apparent molar heat capacity, C
p,, of aqueous NaOH has been measured at temperatures between 50 and 250°C and molalities from 0.05 to 1.5 mol-kg–1. Enthalpies of dilution L were also determined at 99°C and apparent molar relative enthalpies L were calculated up to 1.9 m. Measurements were performed by means of a flow calorimetric apparatus constructed in our laboratory and standardized for C
p, and L with aqueous Na2SO4 and with the formation of water from its ions, respectively. Characteristics and performance of this calorimeter are described in detail. Pitzer's semiempirical equations are used for the representation of the results and a general fitting of C
p, data is reported using also recent literature values measured between 4 and 55°C. The fitted parameters are finally utilized, through an integration procedure, to derive a general equation to calculate L at any temperature between 4 and 250°C. 相似文献
107.
Bersani D Antonioli G Lottici PP Casoli A 《Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy》2003,59(10):2409-2417
Micro-Raman spectroscopy, combined with gas chromatography and ultra-violet fluorescence photography, was used to study some wall paintings in the S. Giovanni Evangelista Abbey in Parma, Italy. The restoration of some painted chapels enabled a comparison between two painters of the 16th century: Parmigianino (Girolamo Francesco Maria Mazzola, 1503-1540) and Michelangelo Anselmi (1492?-1556?). Micro-Raman spectroscopy determined the palette used by the artists, leading to the identification of different white, yellow, red, brown, green, blue and black pigments. Some pigments are evidence of later restorations. Gas chromatography combined with mass spectroscopy revealed the presence of organic binding media and enabled to distinguish between fresco and secco paintings. 相似文献
108.
The reactivity of propene under high pressure has been investigated in the framework of Car-Parrinello molecular dynamics. Changes in structural and electronic properties due to pressure have been analyzed in systems with a density ranging from 0.855 to 2.151 g/cm(3). A ionic collective mechanism which leads to the formation of oligomers has been found by both spin restricted and spin polarized formalism. The maximally localized Wannier centers analysis has allowed us to characterize the addition scheme and to identify a Wannier center with a high spread value involved in the formation of the principal reaction products. 相似文献
109.
Luciana Corda Giovanna Delogu Elias Maccioni Gianni Podda Jos Manuel Blanco Fernandez 《Journal of heterocyclic chemistry》1994,31(6):1337-1342
The mass spectrometric behavior of new tris(polyoxalkyl)amines (tridents) 1–5 have been studied and compared with N-(3,6,9,12-tetraoxatridecyl)-16-aza-18-crown-6 ( 6 ) and 1-morpholino-3,6,9-trioxadecane ( 7 ). The peculiar fragmentation patterns are emphasized. 相似文献
110.
Valensin D Mancini FM Łuczkowski M Janicka A Wisniewska K Gaggelli E Valensin G Łankiewicz L Kozlowski H 《Dalton transactions (Cambridge, England : 2003)》2004,(1):16-22
The copper(II) binding features of the APP(145-155) and APP(145-157) fragments of the amyloid precursor protein, Ac-Glu-Thr-His-Leu-His-Trp-His-Thr-Val-Ala-Lys-NH2 and Ac-Glu-Thr-His-Leu-His-Trp-His-Thr-Val-Ala-Lys-Glu-Thr-NH2 were studied by NMR spectroscopy and NMR findings were supported by UV-vis, CD and EPR spectra. Potentiometric measurements were performed only for the more soluble Ac-Glu-Thr-His-Leu-His-Trp-His-Thr-Val-Ala-Lys-Glu-Thr-NH2 peptide fragment. The following was shown: (i) the imidazole rings of all the three His residues are involved in metal coordination; (ii) metal binding induces ionisation of Leu-148 and His-149 amide nitrogens that complete the donor set to copper(II) in the species dominant at neutral pH; (iii) the unusual coordination scheme of the His-Xxx-His-Xxx-His consensus sequence justifies the high specificity for Cu(II) when compared to SOD-like or albumin-like peptides or even in amyloid Abeta fragments. The present findings may represent the key for interpreting the observed requirement of His residues conservation for the redox cycling between Cu(II) and Cu(I) by soluble APP. 相似文献