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131.
132.
Silvano Ellena Alessandra Viale Roberto Gobetto Silvio Aime 《Magnetic resonance in chemistry : MRC》2012,50(8):529-533
Para‐hydrogen–induced polarization effects have been observed in the 29Si NMR spectra of trimethylsilyl para‐hydrogenated molecules. The high signal enhancements and the long T1 values observed for the 29Si hyperpolarized resonances point toward the possibility of using 29Si for hyperpolarization applications. A method for the discrimination of multiple compounds and/or complex mixtures of hydroxylic compounds (such as steroids), consisting of the silylization of alcoholic functionalities with an unsaturated silylalkyl moiety and subsequent reaction with para‐H2, is proposed. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
133.
Alessandra Bianco Prevot Debora Fabbri Edmondo Pramauro Claudio Baiocchi Claudio Medana Enzo Montoneri Vittorio Boffa 《Journal of photochemistry and photobiology. A, Chemistry》2010,209(2-3):224-231
To promote bio-based products for the industry, six bio-organic substances (cHALi) isolated from yard trimmings (green) and food (humid) urban residues aged under aerobic digestion for 0–60 days were investigated for their potential to perform as sensitizers for azo-dyes photodegradation. Ethylorange (EO) was used as probe molecule at 5 mg L?1 starting concentration and irradiated in a closed Pyrex® cell with a Xenon (1500 W) lamp and a cut-off filter for wavelengths below 340 nm or in a cylindrical photochemical reactor equipped with a 125 W medium pressure Hg lamp. The cHALi/EO ratio in the starting EO solution varied in the 0–200 (w/w) range. The % dye abatement was found a function of the irradiation time, of the type of cHALi substance and of the cHALi/EO ratio. The best results were achieved with cHALi isolated after 7 days biomass aerobic digestion. Total dye abatement was achieved within relatively short few hours. A progressive dye mineralization was observed under the same experimental conditions. On the contrary no significant degradation was evident for the cHALi substances within the same irradiation time. Several hydroxylated azo compounds were identified as likely responsible of residual color after total EO abatement. The results, coupled to the previously reported good performance of the same cHALi substances as auxiliaries for textile dyeing, augur well for the development of both efficient and environmentally friendly textile dyeing processes. 相似文献
134.
Marina Soncin Alessandra Busetti Franco Fusi Giulio Jori Michael A. J. Rodgers 《Photochemistry and photobiology》1999,69(6):708-712
Cu(II)-hematoporphyrin (CuHp) was efficiently accumulated by B78H1 amelanotic melanoma cells upon incubation with porphyrin concentrations up to 52 microM. When the cells incubated for 18 h with 13 microM CuHp were irradiated with 532 nm light from a Q-switched Nd: YAG laser operated in a pulsed mode (10 ns pulses, 10 Hz) a significant decrease in cell survival was observed. The cell photoinactivation was not the consequence of a photodynamic process, as CuHp gave no detectable triplet signal upon laser flash photolysis excitation and no decrease in cell survival was observed upon continuous wave irradiation. Thus, it is likely that CuHp sensitization takes place by photothermal pathways. The efficiency of the photoprocess was modulated by different parameters; thus, while varying the amount of added CuHp in the 3.25-26 microM range had little effect, pulse energies larger than 50 mJ and irradiation times of at least 120 s were necessary to induce a cell inactivation of about 50%. The porphyrin-cell incubation time prior to irradiation had a major influence on cell survival, suggesting that the nature of the CuHp microenvironment can control the efficiency of photothermal sensitization. 相似文献
135.
Alessandra Ricca Jean M. J. Tronchet Jacques Weber 《Journal of computer-aided molecular design》1992,6(6):541-552
Summary The cytotoxic activities of a series of sugar derivatives bearing electrophilic groups (1-cyanovinyl, 4-cyanochromen-2-yl and 3-nitrochromen-2-yl) have been correlated with their electrophilic properties. To this end, an electrophilic index was defined as an isovalue surface where the interaction energy with an incoming model nucelophile (H–) was equal to a predefined value. This index, calculated from extended Hückel wave functions, allows one to quantify the electrophilic character of the substrates and to describe its spatial localization within the molecular volume (at Michael acceptor sites or on other parts of the molecules). Only sugars for which Michael acceptor reactivity was predicted were retained, and they were subdivided into two groups: those showing antiviral activity against a retrovirus and those devoid of such activity. Under these conditions, good correlations between cytotoxic activity and electrophilic reactivity-positive for the first group, negative for the second-were found. In addition, the ratio electrophilicity/sum of the absolute value of the dipole plus its projection along the principal axis of inertia, Z, of the molecule allows one to predict to which of these groups a sugar derivative belongs. 相似文献
136.
Alessandra Carbone 《Annals of Pure and Applied Logic》2009,161(2):139-149
Any arbitrarily complicated non-oriented graph, that is a graph of arbitrarily large genus, can be encoded in a cut-free proof. This unpublished result of Statman was shown in the early seventies. We provide a proof of it, and of a number of other related facts. 相似文献
137.
Maria Alessandra Mariotti 《International Journal of Computers for Mathematical Learning》2002,6(3):257-281
This paper describes a long term teaching experiment carried out with students from the 9th–10th grades. Geometrical constructions in the Cabri environment were selected as a specific field of experience, within which the sense of theory may emerge. The idea of construction constitutes the key to accessing the idea of theorem, moving from a generic idea of justification towards the idea of validating within a geometrical system. The study aims at clarifying the role of the Cabri environment in this teaching-learning processes: analysis of protocols shows the possible evolution of a justification into a proof but at the same time indicates that this evolution is not expected to be simple and spontaneous.This revised version was published online in September 2005 with corrections to the Cover Date. 相似文献
138.
139.
Quadratic Hedging Methods for Defaultable Claims 总被引:2,自引:0,他引:2
We apply the local risk-minimization approach to defaultable claims and we compare it with intensity-based evaluation formulas
and the mean-variance hedging. We solve analytically the problem of finding respectively the hedging strategy and the associated
portfolio for the three methods in the case of a default put option with random recovery at maturity. 相似文献
140.
Alessandra Celletti Luigi Chierchia 《Zeitschrift für Angewandte Mathematik und Physik (ZAMP)》2005,57(1):33-41
A new (iso-energetic) KAM method is tested on a specific three-body problem “extracted” from the Solar system (Sun-Jupiter
+ asteroid 12 Victoria). Analytical results in agreement with the observed data are established. This paper is a concise presentation
of [2].
Supported by the MIUR projects: “Dynamical Systems: Classical, Quantum, Stochastic” and “Variational Methods and Nonlinear
Differential Equations”
Received: February 3, 2004 相似文献