38 research outputs found

    Il Laboratorio partecipato: attività di laboratorio, frequentato da studenti con i loro insegnanti

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    Il Laboratorio Partecipato è una delle iniziative che il Dipartimento di Chimica dell’Università di Pavia svolge da alcuni anni nell’ambito del Piano Lauree Scientifiche. L’attività coniuga l’orientamento degli studenti delle scuole superiori verso la conoscenza di problematiche chimiche moderne con la formazione degli insegnanti, per promuovere una innovazione curricolare che riveda i contenuti e le metodologie dell’insegnamento-apprendimento delle discipline chimiche alla luce degli sviluppi più attuali

    A Preliminary Investigation on Metal Bioaccumulation by Perenniporia fraxinea

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    The lignicolous macrofungus Perenniporia fraxinea has drawn increased attention due to its role as a pathogen of ornamentals in urban sites. The present study investigated the bioaccumulation of heavy metals by P. fraxinea. Sporophores were collected from urban and suburban areas in Pavia (Northern Italy) and analyzed for metals content (Cd, Hg, Pb, Ni, Cr, Cu, Fe, Mn, Zn) by inductively coupled plasma mass spectrometer and inductively coupled plasma optical emission spectroscopy, after microwave acidic digestion. On the basis of the obtained results the potential bioaccumulation capability of P. fraxinea was investigated. The isolates were grown in a culture medium enriched with different concentrations of Cd and Hg, chosen as probes of environmental pollution, and Cu for comparison. As P. fraxinea grows in the presence of Cd, Hg and Cu, it seems to be a potential tool in environmental monitoring

    Photocatalytic reduction of vanadium(V) in TiO2 suspension: chemometric optimization and application to wastewaters

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    The photocatalytic reduction of V(V) to V(IV) over TiO2 in aqueous solution is presented. Experiments were undertaken on air-equilibrated water spiked with V(V) (0.6–20 mg L−1), under UV-A or solar light. A chemometric study was performed to optimize the reduction yield, by considering the most important variables recognized to affect the photocatalytic process. Among pH, irradiation time and catalyst concentration, the two latter proved to be determinant. The good yields achieved (up to 98%), along with the possibility of working in aerated solution, make this procedure simple, rapid and efficient. Although a deep insight on the photochemical mechanisms was beyond our scope, the role of electron donors was investigated, proving the efficiency of 2-propanol, citric acid and formic acid in the acceleration and improvement of V(V) conversion. After irradiation, total vanadium and aqueous V(V) and V(IV) after solid-phase separation on Chelex-100 resin, were determined by inductively coupled plasma optical emission spectroscopy (ICP-OES). The procedure was applied to contaminated wastewaters, combining remediation and possible vanadium recovery as V(IV)

    A comparative test on the sensitivity of freshwater and marine microalgae to benzo-sulfonamides,-thiazoles and-triazoles

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    none5noThe evaluation of the ecotoxicological effects of water pollutants is performed by using different aquatic organisms. The effects of seven compounds belonging to a class of widespread contaminants, the benzo-fused nitrogen heterocycles, on a group of simple organisms employed in reference ISO tests on water quality (unicellular algae and luminescent bacteria) have been assessed to ascertain their suitability in revealing different contamination levels in the water, wastewater, and sediments samples. Representative compounds of benzotriazoles, benzothiazoles, and ben-zenesulfonamides, were tested at a concentration ranging from 0.01 to 100 mg L−1. In particular, our work was focused on the long-term effects, for which little information is up to now available. Species-specific sensitivity for any whole family of pollutants was not observed. On average, the strongest growth rate inhibition values were expressed by the freshwater Raphidocelis subcapitata and the marine Phaeodactylum tricornutum algae. R. subcapitata was the only organism for which growth was affected by most of the compounds at the lowest concentrations. The tests on the biolumines-cent bacterium Vibrio fisheri gave completely different results, further underlining the need for an appropriate selection of the best biosensors to be employed in biotoxicological studies.openCanova L.; Sturini M.; Maraschi F.; Sangiorgi S.; Ferri E.N.Canova L.; Sturini M.; Maraschi F.; Sangiorgi S.; Ferri E.N

    Synthesis and structural characterization of soluble neuromelanin analogs provides important clues to its biosynthesis.

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    Elucidating the structure and biosynthesis of neuromelanin (NM) would be an important step towards understanding its putative role in the pathogenesis of Parkinson's disease. A useful complement to studies aimed at unraveling the origin and properties of this essentially insoluble natural substance is the preparation of synthetic derivatives that resemble NM. With this aim in mind, water-soluble conjugates between dopamine-derived melanin and bovine serum albumin (BSA) were synthesized. Melanin-BSA adducts were prepared with both eumelanic oligomers obtained through the oxidative polymerization of dopamine and pheomelanic oligomers obtained under the same conditions from dopamine and cysteine. Iron ions were added during the synthesis to understand the interaction between the pigment and this metal ion, as the NM in neurons in several human brain regions contains significant amounts of iron. The structures of the conjugates were analyzed by H-1 NMR spectroscopy and controlled proteolysis/MS experiments. The binding of iron(III) ions was evaluated by ICP analysis and EPR spectroscopy. The EPR signal from bound iron(III) indicated high-spin octahedral sites and, as also seen for NM, the signal is coupled to a signal from a radical associated with the melanic components of the conjugates. However, the intensity of the EPR signal from iron suggested a reduced fraction of the total iron, indicating that most of the iron is strongly coupled in clusters within the matrix. The amount of paramagnetic, mononuclear iron(III) was greater in the pheomelanin-BSA conjugates, suggesting that iron clustering is reduced in the sulfur-containing pigment. Thus, the melanin-BSA conjugates appear to be good models for the natural pigmen
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