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61.
Felix M. Sharipov Gilberto M. Kremer 《Zeitschrift für Angewandte Mathematik und Physik (ZAMP)》1995,46(5):680-692
Summary Numerical calculations of heat transfer between two coaxial rotating cylinders at a small temperature difference are carried out over wide ranges of the Knudsen number and the angular velocity. The calculations have been performed based on the S-model of the Boltzmann equation by the discrete velocity method. It has been confirmed that in a rotating gas a radial temperature gradient causes both radial and tangential heat fluxes. Also, it has been found that the radial heat flux is affected by the rotation.On temporary leave from Department of Physics, Urals State University, 620083 Ekaterinburg, Russia. 相似文献
62.
Proper holomorphic mappings between generalized pseudoellipsoids 总被引:3,自引:0,他引:3
Gilberto Dini Angela Selvaggi Primicerio 《Annali di Matematica Pura ed Applicata》1991,158(1):219-229
Summary We characterize the existence of proper holomorphic mappings between pseudoellipsoids of the form
. If f:()() is any such mapping, the existence of a subgroup of Aut (()) such that
is shown equivalent to a condition on the branch locus of f. 相似文献
63.
Ercules E.S. Teotonio Hermi F. Brito Hans Viertler Wagner M. Faustino Oscar L. Malta Gilberto F. de S Maria Cludia F.C. Felinto Regina H.A. Santos Marco Cremona 《Polyhedron》2006,25(18):3488-3494
Europium complexes presenting general formulas [Eu(ACIND)3(H2O)2] and [Eu(ACIND)3(TPPO)2] have been synthesized and characterized. In these formulas ACIND is stands for the ligands 2-acetyl-1,3-indandionate (AIND), 2-isovaleryl-1,3-indandionate (ISOVIND) or 2-benzyl-1,3-indandionate (BIND). The [Eu(ISOVIND)3(H2O)(EtOH)] complex was also prepared and its structure determined by single crystal X-ray analysis, showing that this complex crystallize in a monoclinic space group P21/n with the water molecules bridging through the hydrogen bond. The Eu(III) ion is eight-coordinate in a bicapped trigonal prismatic geometry defined by the oxygen donor atoms with a site of symmetry close to C2ν. Isovaleryl groups in the ISOVIND molecules in the structure are disordered over two positions of the europium complex. Carbon atoms in ethanol molecule are disordered by the thermal vibration. Photoluminescence properties of these complexes in solid state were investigated both experimentally and theoretically, suggesting an efficient ligand-to-metal intramolecular energy transfer process. 相似文献
64.
65.
An original HPLC method coupled to spectrofluorimetric detection is presented for the simultaneous analysis in dried blood spots (DBS) of cocaine and two important metabolites, namely benzoylecgonine (its main metabolite) and cocaethylene (the active metabolite formed in the presence of ethanol). The chromatographic analysis was carried out on a C8 column, using a mobile phase containing phosphate buffer (pH 3.0)-acetonitrile (85:15, v/v). Native analyte fluorescence was monitored at 315 nm while exciting at 230 nm. A fast and feasible sample pre-treatment was implemented by solvent extraction, obtaining good extraction yields (>91%) and satisfactory precision values (RSD<4.8%). The method was successfully applied to DBS samples collected from some cocaine users, both with and without concomitant ethanol intake. The results were in good agreement with those obtained from plasma samples subjected to an original solid-phase extraction procedure on C8 cartridges. The method has demonstrated to be suitable for the monitoring of cocaine/ethanol use by means of DBS or plasma testing. Assays are in progress to apply this method on the street, for the control of subjects suspected of driving under the influence of psychotropic substances. 相似文献
66.
Mário H. Gonzalez Gilberto B. Souza Lucimara A. Forato Ana Rita A. Nogueira 《Talanta》2009,79(2):396-1296
Microwave-assisted sample preparation using diluted nitric acid solutions is an alternative procedure for digesting organic samples. The efficiency of this procedure depends on the chemical properties of the samples and in this work it was evaluated by the determination of crude protein amount, fat and original carbon. Soybeans grains, bovine blood, bovine muscle and bovine viscera were digested in a cavity-microwave oven using oxidant mixtures in different acid concentrations. The digestion efficiency was evaluated based on the determination of residual carbon content and element recoveries using inductively coupled plasma optical emission spectrometry (ICP OES). In order to determine the main residual organic compounds, the digests were characterized by nuclear magnetic resonance (1H NMR). Subsequently, studies concerning separation of nitrobenzoic acid isomers were performed by ion pair reversed phase liquid chromatography using a C18 stationary phase, water:acetonitrile:methanol (75:20:5, v/v/v) + 0.05% (v/v) TFA as mobile phase and ultraviolet detection at 254 nm. Sample preparation based on diluted acids proved to be feasible and a recommendable alternative for organic sample digestion, reducing both the reagent volumes and the variability of the residues as a result of the process of decomposition. It was shown that biological matrices containing amino acids, proteins and lipids in their composition produced nitrobenzoic acid isomers and other organic compounds after cleavage of chemical bonds. 相似文献
67.
Truzzi DR Ferreira AG da Silva SC Castellano EE Lima FC Franco DW 《Dalton transactions (Cambridge, England : 2003)》2011,40(48):12917-12925
The trans-[Ru(NO)(NH(3))(4)(P(OH)(3))]Cl(3) complex was synthesized by reacting [Ru(H(2)O)(NH(3))(5)](2+) with H(3)PO(3) and characterized by spectroscopic ((31)P-NMR, δ = 68 ppm) and spectrophotometric techniques (λ = 525 nm, ε = 20 L mol(-1) cm(-1); λ = 319 nm, ε = 773 L mol(-1) cm(-1); λ = 241 nm, ε = 1385 L mol(-1) cm(-1); ν(NO(+)) = 1879 cm(-1)). A pK(a) of 0.74 was determined from infrared measurements as a function of pH for the reaction: trans-[Ru(NO)(NH(3))(4)(P(OH)(3))](3+) + H(2)O ? trans-[Ru(NO)(NH(3))(4)(P(O(-))(OH)(2))](2+) + H(3)O(+). According to (31)P-NMR, IR, UV-vis, cyclic voltammetry and ab initio calculation data, upon deprotonation, trans-[Ru(NO)(NH(3))(4)(P(OH)(3))](3+) yields the O-bonded linkage isomer trans- [Ru(NO)(NH(3))(4)(OP(OH)(2))](2+), then the trans-[Ru(NO)(NH(3))(4)(OP(H)(OH)(2))](3+) decays to give the final products H(3)PO(3) and trans-[Ru(NO)(NH(3))(4)(H(2)O)](3+). The dissociation of phosphorous acid from the [Ru(NO)(NH(3))(4)](3+) moiety is pH dependent (k(obs) = 2.1 × 10(-4) s(-1) at pH 3.0, 25 °C). 相似文献
68.
Jos A Hernndez-Díaz Jorge JO Garza-García Janet M Len-Morales Adalberto Zamudio-Ojeda Jenny Arratia-Quijada Gilberto Velzquez-Jurez Julio C Lpez-Velzquez Soledad García-Morales 《Molecules (Basel, Switzerland)》2021,26(19)
The use of selenium nanoparticles (SeNPs) in the biomedical area has been increasing as an alternative to the growing bacterial resistance to antibiotics. In this research, SeNPs were synthesized by green synthesis using ascorbic acid (AsAc) as a reducing agent and methanolic extract of Calendula officinalis L. flowers as a stabilizer. Characterization of SeNPs was performed by UV-vis spectrophotometry, infrared spectrophotometry (FTIR), scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), and transmission electron microscopy (TEM) techniques. SeNPs of 40–60 nm and spherical morphologies were obtained. The antibacterial activity of marigold extracts and fractions was evaluated by disk diffusion methodology. The evaluation of SeNPs at different incubation times was performed through the colony-forming unit (CFU) count, in both cases against Serratia marcescens, Enterobacter cloacae, and Alcaligenes faecalis bacteria. Partial antibacterial activity was observed with methanolic extracts of marigold leaves and flowers and total inhibition with SeNPs from 2 h for S. marcescens, 1 h for E. cloacae, and 30 min for A. faecalis. In addition, SeNPs were found to exhibit antioxidant activity. The results indicate that SeNPs present a potentiated effect of both antimicrobial and antioxidant activity compared to the individual use of marigold extracts or sodium selenite (Na2SeO3). Their application emerges as an alternative for the control of clinical pathogens. 相似文献
69.
In this paper we investigate the convolution Hankel transforms on the Zemanian spaces of Hankel transformable functions and distributions. The convolution Hankel transform is defined on generalized functions by using the adjoint method. Our new definition includes as special cases other known definitions of the convolution Hankel transform of distributions. Finally we establish a distributional inversion formula for the transformation under consideration involving Bessel differential operators. 相似文献
70.
Rajesh Kumar T. Prabukanthan P. Harichandran G. Theerthagiri J. Tatarchuk Tetiana Maiyalagan T. Maia Gilberto Bououdina M. 《Journal of Solid State Electrochemistry》2018,22(4):1197-1207
Journal of Solid State Electrochemistry - Gd3+ (gadolinium)-doped ZnSe thin films (1 to 5 mol%) are grown onto indium-doped tin oxide (ITO) glass substrate by single-step electrochemical... 相似文献