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61.
Richard St‐Louis Stephen de Mora milien Pelletier Bill Doidge Daniel Leclair Igor Mikaelian Daniel Martineau 《应用有机金属化学》2000,14(4):218-226
Butyltin (tributyltin TBT; dibutyltin DBT and monobutyltin MBT) speciation was measured in the liver of beluga whales from the St Lawrence Estuary and Hudson Strait (northern Quebec). Using GC–MS, liver samples were analysed from 21 beluga whales found dead, stranded along the shores of the St Lawrence during the period 1995–1998. In all cases, including a neonate specimen, the liver was contaminated with butyltin compounds with concentrations in the range 0.04–2.1 mg Sn kg−1 on a dry weight basis. Liver samples of five beluga whales from Hudson Strait obtained in the summer of 1998 were also analysed. For these animals, hepatic butyltin concentrations were consistently below the detection limit (<0.5 ng Sn g−1 for MBT and <0.2 ng Sn g−1 for DBT and TBT). Compared with published data on the contamination by TBT of the marine mammals of the St Lawrence in 1988, these contemporary results clearly indicate that the level of contamination of the beluga whales in this coastal marine ecosystem has not decreased ten years after regulating the use of TBT‐based antifoulants on small craft. Copyright © 2000 John Wiley & Sons, Ltd. 相似文献
62.
Structure elucidation of configurational isomers of nitrile‐substituted spirocyclopropyloxindoles by NMR spectroscopy,molecular modeling,and X‐ray crystallography 下载免费PDF全文
63.
Silvana Alborés Paola Mora María José Bustamante María Pía Cerdeiras Laura Franco Fraguas 《Applied biochemistry and biotechnology》2014,172(4):2081-2090
A lectin was isolated from fruiting bodies of the mushroom Gymnopilus spectabilis (GSL) by ionic exchange chromatography. The lectin agglutinates mouse red cells exhibiting broad specificity towards several monosaccharides including the N-acetylneuraminic acid. Agglutination was also inhibited by the glycoproteins: fetuin, lactoferrin, and recombinant erythropoietin. GSL is a glycoprotein possessing 16 % of carbohydrates; the SDS-PAGE showed two bands with molecular mass of 52.1 and 64.4 kDa. Isoelectric focusing displayed microheterogeneity, with two bands at pIs 5.1 and 5.3. The lectin was stable between pH 2 and pH 8 while at pH 10, the agglutination decayed to 50 % of initial activity. Incubation at 40 and 80 °C led to 50 and 100 % loss in activity of the lectin, respectively. Synthesized GSL-Sepharose interacts with serum pregnant mare gonadotropin, and at least two subpopulations of this glycoprotein were separated. There was no interaction between transferrin and soluble GSL while a partial recognition was achieved with GSL-Sepharose. The terminal sialic acid seems to play an active role in modifying the interaction with GSL, depending if the lectin is in a soluble or immobilized form. The purified lectin inhibited in vitro the growth of Staphylococcus aureus and Aspergillus niger. 相似文献
64.
M. Borghesi T. Toncian J. Fuchs C. A. Cecchetti L. Romagnani S. Kar K. Quinn B. Ramakrishna P. A. Wilson P. Antici P. Audebert E. Brambrink A. Pipahl R. Jung M. Amin O. Willi R. J. Clarke M. Notley P. Mora T. Grismayer E. D’Humières Y. Sentoku 《The European physical journal. Special topics》2009,175(1):105-110
The acceleration of high-energy ion beams following the interaction of short (t < 1 ps) and intense (Iλ2 > 1018 W cm-2 μm2) laser pulses with solid targets is a field of research currently attracting high interest in the scientific community, due
to some of the unique properties of these ion sources, promising routes toward the optimization of their energy content, and
a number of possible, innovative applications in the scientific, technological and medical areas. Work on the characterization
and development of these sources has progressed enormously over the past few years, thanks to the contribution of many groups
worldwide. This paper will report some recent results, obtained in experiments carried out at the RAL and LULI laboratories,
in which we investigated the ion acceleration mechanism, developed a technique to control the ion beam divergence and energy
spectrum, and applied a proton radiography technique to investigate electric and magnetic field production following laser-matter
interaction. 相似文献
65.
Armando Herize José R. Mora Jesus Lezama Edgar Marquez Tania Córdova Gabriel Chuchani 《Journal of Physical Organic Chemistry》2009,22(2):170-176
The elimination kinetic of methyl carbazate in the gas phase was determined in a static system over the temperature range of 340–390 °C and pressure range of 47–118 Torr. The reaction is homogeneous, unimolecular, and obeys a first order rate law. The decomposition products are methyl amine, nitrous acid, and CO gas. The variation of the rate coefficients with temperatures is given by the Arrhenius expression: log k1 (s?1) = (11.56 ± 0.34) ? (180.7 ± 4.1) kJ mol?1(2.303 RT)?1. The estimated kinetics and thermodynamics parameters are in good agreement to the experimental values using B3LYP/6‐31G (d,p), and MP2/6‐31G (d,p) levels of theory. These calculations imply a molecular mechanism involving a concerted non‐synchronous quasi three‐membered ring cyclic transition state to give an unstable intermediate, 1,2‐oxaziridin‐3‐one. Bond order analysis and natural charges implies that polarization of O (alkyl)? C (alkyl) bond of the ester is rate determining in this reaction. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
66.
In this paper,dynamic similarity conditions are derived for discrete element simulations by non-dimensionalising the governing equations.These conditions must b... 相似文献
67.
Marta Lewicka Maria Giovanna Mora Mohammad Reza Pakzad 《Comptes Rendus Mathematique》2009,347(3-4):211-216
We study the Γ-limit of 3d nonlinear elasticity for shells of small, variable thickness, around an arbitrary smooth 2d surface. To cite this article: M. Lewicka et al., C. R. Acad. Sci. Paris, Ser. I 347 (2009). 相似文献
68.
Stashenko EE Mora AL Cervantes ME Martínez JR 《Journal of chromatographic science》2006,44(6):347-353
Specific chromatographic methodologies are developed for the analysis of carboxylic acids (C(2)-C(6), benzoic) and aldehydes (C(2)-C(10)) of low molecular weight in diverse matrices, such as air, automotive exhaust gases, human breath, and aqueous matrices. For carboxylic acids, the method is based on their reaction with pentafluorobenzyl bromide in aqueous solution, followed by the separation and identification of the resultant pentafluorobenzyl esters by means of headspace (HS)-solid-phase microextraction (SPME) combined with gas chromatography (GC) and electron capture detection (ECD). Detection limits in the microg/m(3) range are reached, with relative standard deviation (RSD) less than 10% and linear response (R(2) > 0.99) over two orders of magnitude. The analytical methodology for aldehydes is based on SPME with simultaneous derivatization of the analytes on the fiber, by reaction with pentafluorophenylhydrazine. The derivatization reagent is previously deposited on the SPME fiber, which is then exposed to the gaseous matrix or the HS of the sample solution. The pentafluorophenyl hydrazones formed on the fiber are analyzed selectively by means of GC-ECD, with detection limits in the ng/m(3) range, RSD less than 10%, and linear response (R(2) > 0.99) over two orders of magnitude. 相似文献
69.
Chemical activation of carbon mesophase pitches 总被引:10,自引:0,他引:10
Mora E Blanco C Pajares JA Santamaría R Menéndez R 《Journal of colloid and interface science》2006,298(1):341-347
This paper studies the chemical activation of mesophase pitches of different origins in order to obtain activated carbons suitable for use as electrodes in supercapacitors. The effect that the activating agent (NaOH, LiOH, and KOH), the alkaline hydroxide/pitch ratio, and the activation temperature had on the characteristics of the resultant activated carbons was studied. LiOH was found to be a noneffective activating agent, while activation with NaOH and KOH yielded activated carbons with high apparent surface areas and pore volumes. The increase of the KOH/pitch ratio caused an increase of the chemical attack on the carbon, producing higher burnoffs and development of porosity. Extremely high apparent surface areas were obtained when the petroleum pitch was activated with 5:1 KOH/carbon ratio. The increase of the activation temperature caused an increase of the burnoff, although the differences were not as significant as those derived from the use of different proportions of activating agent. 相似文献
70.
Libia L. Julio Jesus Lezama Alexis Maldonado José R. Mora Gabriel Chuchani 《Journal of Physical Organic Chemistry》2014,27(5):450-455
The kinetics of the gas‐phase elimination of α‐methyl‐trans‐cinamaldehyde catalyzed by HCl in the temperature range of 399.0–438.7 °C, and the pressure range of 38–165 Torr is a homogeneous, molecular, pseudo first‐order process and undergoing a parallel reaction to produce via (A) α‐methylstyrene and CO gas and via (B) β‐methylstyrene and CO gas. The decomposition of substrate E‐2‐methyl‐2‐pentenal was performed in the temperature range of 370.0–410.0 °C and the pressure range of 44–150 Torr also undergoing a molecular, pseudo first‐order reaction gives E‐2‐pentene and CO gas. These reactions were carried out in a static system seasoned reactions vessels and in the presence of toluene free radical inhibitor. The rate coefficients are given by the following Arrhenius expressions:
- Products formation from α‐methyl‐trans‐cinamaldehyde
- α‐methylstyrene :
- β‐methylstyrene :
- Products formation from E‐2‐methyl‐2‐pentenal
- E‐2‐pentene :