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51.
Hsiu-Ling Hsu Rosilda Selvin L. Selva Roselin Prajitha Kumari Jia-Wei Cao 《Reaction Kinetics and Catalysis Letters》2009,98(2):265-272
The photocatalytic properties of nanocrystalline TS-1 were confirmed via the degradation of an aqueous solution of the model
compound methyl orange (MO). The light intensity and quantum yield were measured by ferrioxalate actinometry and the values
are 1.7 × 10−5 einstein l−1 s−1 and 0.71, respectively. The experimental parameters such as catalyst loading, pH and initial concentration of MO were optimized
at 1.5 g/L, 10 and 300 μM, in order. The results showed that the dye molecules are completely degraded to CO2, H2O and simple inorganic ions. 相似文献
52.
53.
Bandini M Cozzi PG Giacomini M Melchiorre P Selva S Umani-Ronchi A 《The Journal of organic chemistry》2002,67(11):3700-3704
Low sensitivity toward traces of moisture and high tolerance of different functional groups make indium tribromide suitable for carrying out multistep synthetic sequences. In particular, we have realized a 1,4-conjugated addition of indoles/thiols to alpha,beta-unsaturated ketones mediated by a catalytic amount (10 mol %) of InBr(3) obtaining the desired beta-substituted ketones in good yields. The Lewis acidity of indium salts was not affected by coordinating and acid nucleophiles; therefore, the subsequent catalytic 1,2-addition of Me(3)SiCN to carbonyl compounds can be performed in one pot. With the optimized atom-efficient protocol, several polyfunctionalized alpha-silyloxy cyanohydrins were synthesized in good to excellent yields (up to 97%) and a notable level of simple 1,3-diastereoselection (up to 84:16) was recorded in the case of 2-cyclohexen-1-one 2c. 相似文献
54.
Alvise Perosa Pietro Tundo Maurizio Selva 《Journal of molecular catalysis. A, Chemical》2002,180(1-2):169-175
The multiphase heterogeneous enantioselective hydrogenation of acetophenone in the presence of cinchona-modified Pt/C was investigated. The system demonstrated the feasibility of this reaction on non-activated ketones. The reaction proceeded selectively, at room temperature and atmospheric pressure, towards the formation of 1-phenylethanol, with up to 20% ee (enantiomeric excess) of either enantiomer depending on the modifier used. A mode of action of the modifier is proposed to account for the mechanism. A comparison with other systems indicates that the investigated system likely acts by a different mechanism, and that it is quite specific for acetophenone. 相似文献
55.
A generalized Kirchhoff-Stokes equation for the sound attenuation coefficient is derived from irreversible thermodynamics. The discrepancy between the experimental value of the absorption coefficient and the value calculated from the generalized equation is analyzed. In particular, the so-called effective bulk viscosity and the transport coefficient which links a chemical reaction to the viscous processes are emphasized. An experimental example illustrating the general situation is also given. 相似文献
56.
Antonio Selva Pietro Traldi Paolo Ventura Vincenzo Dalla Valle 《Journal of mass spectrometry : JMS》1982,17(10):524-528
Ortho Phthalamic acids under electron impact show a retrosynthetic reaction leading to both phthalic anhydride and amine complementary ions, the corresponding neutrals of which are the usual synthetic precursors of the original compounds. The single case of a primary amine derivative is examined, which shows the formation of [M? H2O]+˙ ions having the structure of the related N-substituted imide, by a process which parallels a well known thermal reaction. It also gives the species [C8H6NO2]+ (of the same nominal mass as phthalic anhydride), the structure of which is still under study. Ionic structures are supported by collision induced mass analyzed ion kinetic energy spectra. 相似文献
57.
Antonio Selva Francesco Ferrario Antonio Saba 《Journal of mass spectrometry : JMS》1987,22(4):189-196
The gaseous ionic products of 1-diazo-3-phenoxypropan-2-one upon electron impact show that cyclization reactions, which have counterparts in condensed-phase chemistry, occur in competition with a mass spectral Wolff type rearrangement. 相似文献
58.
Andrea Mele Giuseppina Raffaini Fabio Ganazzoli Antonio Selva 《Journal of inclusion phenomena and macrocyclic chemistry》2002,44(1-4):219-223
The structure of gaseous charged host-guest adducts ofcyclodextrins (CDs) generated by mass spectrometry (MS) still requires to be addressed correctly,as these adducts could be true inclusion complexes or non-specific proton bound heterodimers(PBHs). The present theoretical study of inclusion complex vs. PBH of 5-methoxytryptammonium ion(5-MTA+) with -CD in vacuo by energy minimisation and moleculardynamics proved that the most stable forms of -CD/5-MTA+ non-covalent associationare inclusion complexes. PBHs evolved to genuine inclusion complexes with two differenthost-guest arrangements during MD runs. 相似文献
59.
Pereda MD Reigosa M Fernández Lorenzo de Mele M 《Bioelectrochemistry (Amsterdam, Netherlands)》2008,72(1):94-101
The extended use of metallic biomaterials yields to increasing sources of metal ions within the human body and may result in inflammation of the surrounding tissues, cell damage, and cancer. The aim of this study was to investigate the relationship between the radial diffusion of metal ions released from a metal disk by the corrosion process and the toxic effect on a cell line that grew around it. Results obtained with the metal disks (direct contact) were compared with assays made with extracts obtained from the dissolution of a metallic sample ex situ and then added to the cell culture to elucidate the cause of apparent inconsistencies in previous reports. The change of copper concentration due to corrosion and transient diffusion of copper ions from the copper disks into the cell line was evaluated according to Fick's 2nd law. Surviving cells distribution was interpreted considering the radial and time-dependence of copper concentration. We concluded that the toxic effect on those cells close to metallic biomaterials may be underestimated when only the extract methodology is employed for cytotoxic tests or when during the experiments with disks the presence of concentration gradients and the non-homogeneous distribution of dead cells are disregarded. 相似文献
60.