2 research outputs found
Effects of dissolved organic matter (DOM) at environmentally relevant carbon concentrations on atrazine degradation by <em>Chelatobacter heintzii</em> SalB
No full textInternational audienceThe dissolved organic matter (DOM) is the term used for organic components of natural origin present in the soil solution and is probably the most available C-source that primes microbial activity in subsoils. Contrasting effects of organic C components on pesticide degradation have been reported; however, most studies have used model organic compounds with compositions and concentrations which differ substantially from those found in the environment. Degradation of atrazine (AT) by Chelatobacter heintzii SalB was monitored in liquid batch assays in the absence or presence of well-defined model C compounds (glucose, gluconate and citrate) as model DOM (mDOM) or complex, less-defined, environmental DOM solutions (eDOM: isolated humic substances, soil and plant residue extracts) at environmentally relevant concentrations. Glucose significantly increased AT degradation rate by more than a factor of 8 at and above 2.5 mg C L (-aEuro parts per thousand 1). Optical density measurements showed that this stimulation is related to microbial growth. Gluconate and citrate had no effects unless at non-relevant concentrations (1,000 mg DOC L (-aEuro parts per thousand 1)) at which stimulations (gluconate) or inhibitions (citrate) were found. The effects of eDOM added at 10 mg DOC L (-aEuro parts per thousand 1) on AT degradation were generally small. The AT degradation time was reduced by factors 1.4-1.9 in the presence of humic acids and eDOM from soils amended with plant residues; however, no effects were found for fulvic acids or eDOM from a soil leachate solution or extracted from unamended peat or forest soil. In conclusion, DOM supplied as both mDOM and eDOM did not inhibit AT degradation at environmentally relevant concentrations, and stimulation can be found for selected DOM samples and this is partly related to its effect on growt
Nous manuscrits de l’obra mèdica d’Arnau de Vilanova
No full textThis article is a first presentation of the results obtained by reviewing the manuscripts of Arnau de Vilanova’s medical works in the development of the Arnau BD database, in which the codices of the corpus attributed to this medieval physician are collected. Our review has allowed not only to gather the previously known witnesses of Arnau’s medical writings in a single resource, but also to discover 36 manuscripts containing one or more of his texts that had gone unnoticed in the prior scholarship on this author.[ca] Aquest article és una primera presentació dels resultats obtinguts en el procés de revisió dels manuscrits de l’obra mèdica d’Arnau de Vilanova en el marc del desenvolupament de la base de dades Arnau BD dedicada a recopilar els còdexs del corpus atribuït a aquest metge medieval. La nostra revisió ha permès no tan sols reunir en un sol recurs els testimonis coneguts prèviament dels escrits mèdics d’Arnau sinó també descobrir 36 manuscrits amb un o més textos seus que havien passat desapercebuts en els estudis arnaldians anteriors
