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31.
The electrochemical determination of aqueous Hg(II) by anodic stripping voltammetry (ASV) at a solid gold electrode is described. The aim of this work is to optimise all factors that can influence this determination. Potential wave forms (linear sweep, differential pulse, square wave), potential scan parameters, deposition time, deposition potential and surface cleaning procedures were examined for their effect on the mercury peak shape and intensity. Five supporting electrolytes were tested. The best responses were obtained with square wave potential wave form and diluted HCl as supporting electrolyte. Electrochemical and mechanical surface cleaning, aimed at removing the amount of mercury deposited onto the gold surface, were necessary for obtaining a good performance of the electrode. Response linearity, repeatability, accuracy and detection limit were also evaluated. 相似文献
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A. Tumino M. Lattuada S. Romano C. Spitaleri D. Vinciguerra Z. Basrak O.Yu. Goryunov V.V. Ostashko S. Szilner P. Figuera D. Lo Presti C. Petta N. Randazzo S. Reito G.V. Russo S. Tudisco 《The European Physical Journal A - Hadrons and Nuclei》2001,12(3):327-334
High-spin states of 24Mg produced in the 16O + 12C interaction and decaying into the 16Og.s. + 8Beg.s. channel have been observed in the excitation region between 35 and 52 MeV. Spins have been assigned on the basis of the analysis
of the measured angular correlations. Some of these states with positive parity correspond to the known resonances of the
12C( 12C, 8Beg.s.) 16O reaction belonging to the 16O-2α rotational band of 24Mg. Moreover other resonances show up at higher excitation energy with an energy-spin relationship again suggesting a 16O-2α cluster structure for the associated configuration.
Received: 6 July 2001 / Accepted: 16 October 2001 相似文献
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A Randazzo G Bifulco C Giannini M Bucci C Debitus G Cirino L Gomez-Paloma 《Journal of the American Chemical Society》2001,123(44):10870-10876
Two new metabolites, named halipeptins A and B, have been isolated from the marine sponge Haliclona sp. Their structures were determined by extensive use of one- and two-dimensional NMR experiments, mass spectrometry, and UV and IR spectroscopy. Halipeptin A is a novel 17-membered cyclic depsipeptide, consisting of five residues including two alanines (with L stereochemistry) and three new residues that appear to be previously undescribed from natural sources: 1,2-oxazetidine-4-methyl-4-carboxylic acid, 3-hydroxy-2,2,4-trimethyl-7-methoxydecanoic acid (HTMMD), and N-methyl-delta-hydroxyisoleucine. The HTMMD residue is substituted with 3-hydroxy-2,2,4-trimethyl-7-hydroxydecanoic acid in halipeptin B. Halipeptin A was found to possess very potent anti-inflammatory activity in vivo, causing about 60% inhibition of edema in mice at the dose of 300 microg/kg (i.p.). 相似文献
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Dr. Massimiliano Gaeta Dr. Giuseppe Sortino Dr. Rosalba Randazzo Dr. Ilenia Pisagatti Prof. Anna Notti Prof. Maria Elena Fragalà Prof. Melchiorre F. Parisi Prof. Alessandro D'Urso Prof. Roberto Purrello 《Chemistry (Weinheim an der Bergstrasse, Germany)》2020,26(16):3515-3518
The hierarchical assembly, in aqueous solution, of a new multi-metalloporphyrin/calixarene aggregate has been accomplished. In this supramolecular system transfer of chirality, from the outermost components to the central porphyrin reporter, takes place as a result of favorable and fully noncovalent long-range electronic communication. 相似文献
36.
Malandrino M Abollino O Giacomino A Aceto M Mentasti E 《Journal of colloid and interface science》2006,299(2):537-546
The sorption behaviour of vermiculite has been studied with respect to cadmium, copper, lead, manganese, nickel, and zinc as a function of pH and in the presence of different ligands. The continuous column method was used in order to evaluate the feasibility to use the clay in wastewater purification systems. The total capacity of vermiculite was found to decrease in the following order: Mn > Ni > Zn > Cd > Cu > Pb. The adsorption of metal ions on vermiculite decreases with decreasing pH and increasing ionic strength. In general, the metal uptake on the clay was hindered by the presence of strong complexing agents in solution and it decreases with increasing of the complexation constants of the ligands with exception of cysteine and tiron. It is necessary, hence, to consider all these factors to effectively predict the uptake efficiency of this sorbent. However, it is possible to conclude that the vermiculite has good potentialities for cost-effective treatments of metal-contaminated wastewaters. 相似文献
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Ornella Abollino Agnese Giacomino Mery Malandrino Giuseppina Piscionieri Edoardo Mentasti 《Electroanalysis》2008,20(1):75-83
The aim of this work is the development of a procedure for the determination of aqueous Hg(II) by anodic stripping voltammetry at a gold nanoparticle‐modified glassy carbon electrode (AuNPs‐GCE). The signal of aqueous Hg(II) was measured in the square wave mode; the effect of potential scan parameters, deposition potential and deposition time on the analytical signal was examined. The supporting electrolyte was 0.06 M HCl. The repeatability, the linearity, the accuracy, the detection limit of the procedure and the interferences of other cations and of anions were evaluated. The performance of the AuNPs‐GCE was compared with those of a solid (SGE) and a film (FGE) gold electrode: the AuNPs‐GCE showed to provide lower detection limits and higher repeatability. The renewable surface permits to eliminate memory effects, to maintain a stable baseline and response, and to avoid frequent mechanical cleaning steps. The applicability of the AuNPs‐GCE for Hg(II) determination in drinking waters, sediments and pharmaceuticals was demonstrated. 相似文献
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The chemical synthesis and 1H NMR analysis of a novel bicyclic uridine derivative, with a 18-crown-6 ether moiety fused at the ribose 2- and 3-positions, as first example of a hitherto unknown class of ribose-modified nucleosides, are here described. NMR-based conformational analysis studies showed for the modified nucleoside a marked preference for an N-type sugar puckering and the nucleobase in the anti conformation, with the uracil favouring the coordination of a sodium ion hosted in the crown ether. 相似文献
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The biosynthetic origin of the hydroxyisopropyl group of fusicoccin 1 has been determined. Two out of the eight tritium mevalonoid atoms retained in 1 following incorporation of MVA-[2-3H2,2-14C] have been located at C-20; whilst none has been found in the C-19 methylene group. 相似文献