1,721,028 research outputs found
Gas chromatographic determination of organic micropollutants in samples of sewage sludge and compost: Behaviour of PCB and PAH during composting
No full textIon-exchange voltammetry of trace mercury(II) at glassy carbon electrodes coated with a cationic polypyrrole derivative. Application to pore-waters analysis.
No full textContamination in Mytilus galloprovincialis by chlorinated hydrocarbons (PCBs and pesticides), PAHs and heavy metals in the Lagoon of Venice
No full textMicellar promoted alkenes isomerization in water mediated by a cationic half-sandwich Ru(II) complex
Full text linkMicellar media in water provide a simple and efficient environment to favor the double bond isomerization of terminal alkenes catalyzed by the cationic half-sandwich complex 1 at 95 °C. The micellar medium favors both catalyst dissolution in water by means of ion-pairing with the preferred anionic surfactants as well as substrate dissolution thus favoring its conversion into products
Synthesis and characterization of a homoleptic titanium dihydrobis(pyrazol-1-yl)borate complex
No full textCorrelation between Inorganic (heavy metals) and organic (PCBs, PAHs) micropollutant concentrations during sewage sludge composting process
No full textOrganic micropollutants (PAHs, PCBs, Pesticides) in seaweeds of the lagoon of Venice
No full textSamples of seven genera of seaweeds (Ulva, Gracilaria, Porphyra, Grateloupia, Undaria, Fucus and Cystoseira), which can be used as environmental biomonitors and in several applications like human alimentation, animal feeding and cosmetics, were collected in four sampling sites in the Lagoon of Venice in spring and autumn 1999 with the aim of determining the contamination due to organic micropollutants (polychlorinated biphenyls. PCBs; chlorinated pesticides; polycyclic aromatic hydrocarbons, PAHs). On an average, most of the considered species were contaminated especially by PAHs (up to 56 ng g(-1) dry wt. (dw)) whereas concentrations of PCBs and pesticides in macroalgal tissues were significantly correlated and did not exceed 5 ng g-1 dw. Among the studied genera the most contaminated by PAHs were Ulva, Undaria and Cystoseira. The highest concentrations of PCBs and pesticides were found in Cystoseira, Fucus and Gracilaria. The least contaminated genus was Porphyra. Although macroalgal specimens were sampled in differently contaminated areas placed from the mainland to the Lido Lagoon mouth, no quantitatively meaningful differences of concentrations were found among the sampling stations. (C) 2003 Editions scientifiques et medicales Elsevier SAS and Ifremer/CNRS/IRD. All rights reserved
Organocatalytic Enantioselective Epoxidation of\ud Some Aryl-Substituted Vinylidenebisphosphonate\ud Esters: On the Way to Chiral Anti-Osteoporosis Drugs
Full text linkThe synthesis of a new class of epoxide derivatives from prochiral vinylidene bisphosphonate (VBP) precursors is reported using hydrogen peroxide as the terminal oxidant. The reaction is carried out using a series of possible organic catalysts having a basic character, the best results being observed using quinine and sparteine. These catalysts not only provide from good to excellent epoxide yields with a large variety of VBPs but also interesting enantioselectivities in the 67-96% ee range at least in the case of the Ph and m-MeO-Ph VBP derivatives opening the way to a number of chiral anti-osteoporosis potentially active pharmaceutical ingredient
Electrochemical measurement of mercury concentration profiles in pore-waters of sediments of the Venice lagoon by ion-exchange voltammetry at polymer modified electrodes
No full textSupramolecular Encapsulation of Neutral Diazoacetate Esters and Catalyzed 1,3-Dipolar Cycloaddition Reaction by a Self-Assembled Hexameric Capsule
Full text linkDiazoacetate esters proved to be suitable neutral guests for
the self-assembled resorcin[4]arene hexameric capsule. The hydrogen- bonded supramolecular host catalyzed the 1,3-dipolar cycloaddition reaction between diazoacetate esters and electron- poor alkenes such as acrolein, acrylonitrile, crotonaldehyde, trans-2-hexenal, methyl, and butyl acrylate,
which led to the corresponding 4,5-dihydro-1H-pyrazole
derivatives. The cycloaddition reaction occurred within the
cavity of the capsule. In fact, substantial inhibition of the catalytic activity was observed by employing tetraethylammonium tetrafluoroborate characterized by greater affinity for the hexameric capsule as a competitive guest; its presence inhibited access of the substrates. The 1,3-dipolar cycloaddition reaction between diazoacetate esters and acrylate esters of different lengths showed a significant degree of substrate selectivity owing to the encapsulation of the reagents before the cycloaddition reaction
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