169,717 research outputs found
Applicazione di un tensioattivo micellare per la bonifica del suolo da idrocarburi petroliferi.
No full textIn questa nota vengono riportati i risultati di una sperimentazione effettuata per la messa a punto, in laboratorio, di una procedura di bonifica di suoli inquinati da idrocarburi petroliferi. Le prove di decontaminazione sono state effettuate su suoli artificiali trattati con diesel commerciale e con un tensioattivo “micellare” denominato F-500 (Hazard Control Technologies Inc. – Fayetteville GA USA) che attualmente è utilizzato come agente estinguente e come disperdente per la bonifica dell’inquinamento da idrocarburi in ambiente marino. L’indagine ha previsto l’utilizzo di organismi acquatici (crostaceo Daphnia magna) e terrestri (oligochete Eisenia foetida e dicotiledone Cucumis sativus). I saggi con D. magna sono stati effettuati sia su eluati, ottenuti da terreni impaccati in colonne ed eluiti con acqua, sia su elutriati ottenuti unendo terreno e acqua (rapporto 1:4). Con E. foetida sono stati effettuati sia test di screening su filtri di carta imbibiti con la matrice elutriato sia test sul suolo con esposizione diretta degli organismi ai terreni trattati; quest’ultima tipologia di test è stata adottata anche per i saggi con C. sativus. Le prove effettuate con D. magna hanno evidenziato una riduzione della tossicità degli eluati/elutriati dei terreni trattati con F-500; tale risultato è stato confermato anche con i test effettuati con E. foetida e C. sativus. La riduzione della tossicità rilevata a seguito dei trattamenti con F-500 è dovuta, probabilmente, alla composizione del prodotto che è in grado di incapsulare le molecole di idrocarburi rendendole meno disponibili per gli organismi esposti
Exposition biomarkers to organophosphorus pesticides in Tigriopus fulvus Fischer (Copepoda, Harpacticoida)
No full textTest ecotossicologici su materiali di scavo.
No full textGli autori riportano i risultati di uno studio ecotossicologico, effettuato su materiali di scavo (metabasalti, calcescisti e serpentiniti), necessario per la valutazione dell’impatto a seguito del loro utilizzo per la costruzione di una “colmata” in ambito marino-aeroportuale. A tale scopo sull’elutriato del materiale sono stati effettuati saggi di ecotossicità utilizzando l’alga fitoplanctonica Dunaliella tertiolecta e il crostaceo Artemia franciscana, mentre sul “tal quale” è stato utilizzato il copepode Tigriopus fulvus. Il materiale di scavo è stato analizzato per la determinazione di alcuni metalli pesanti (Cr, Ni, Co, Cu, As) e sono state effettuate prove di bioaccumulo degli stessi impiegando il polichete marino Perinereis spp. e il bivalve Mytilus galloprovincialis. I risultati delle analisi effettuate non hanno messo in evidenza, per le tre tipologie di materiali esaminati, un effetto ecotossicologico significativo sia per la matrice elutriato sia per il materiale “tal quale”. Per quanto riguarda l’esposizione ai metalli pesanti, M. galloprovincialis ha mostrato di bioaccumulare cromo e nickel quando esposto ai metabasalti e cromo nelle prove di esposizione alle calcescisti; i policheti hanno mostrato di bioaccumulare soprattutto rame ed arsenico quando esposti a calcescisti e serpentiniti
Utilization of marine crustaceans as study models: a new approach in Marine Ecotoxicology for European (REACH) regulation
No full textPollution problems affect greatly the aquatic environments that are mainly sensitive to several typologies of contamination, such as chemical pollution, oil dumping, microbiological contamination from sewers, etc. To date a lot of chemicals are utilized in productive processes and many new substances are synthesized every year; the utilization and introduction of these newly synthesized chemicals into the environment and in production cycles must be approved after an accurate evaluation of their eventual toxic properties against selected organisms with the main purpose to protect the safety of plants and animals and the human health. These evaluations need to be carried out using test-species which are representative of the environmental compartment under consideration; in this connection, the availability of test-species able to furnish reliable and cheap results and to evaluate the activity of pollutants at the individual and ecosystem level is essential. To date the availability of test-species, easy to collect and to rear, and sensitive to different xenobiotics, is an important aspect in ecotoxicology in order to characterize the risk of chemicals. In the aquatic environment an ideal battery of organisms should comprise the representative links of the food web: a primary producer, such as a microalga, a primary consumer (invertebrate), such as a crustacean, and a secondary consumer (vertebrate), such as a fish. In this connection, the new European regulation REACH (Registration, Evaluation, Authorization of CHemicals) n. 1907/2006 introduces an integrated system for the management of all produced/imported chemicals for an amount 31 ton/year and states that all substances destined to be used in the EU and to be introduced into the production processes must be subject to accurate evaluation including toxicity tests on selected organisms. All tests indicated by REACH must be carried out in conformity with well defined analysis methods determined by the EU or, failing that, according to the OECD guidelines or to other determined methods. Furthermore, all tests must be performed in conformity with the principles of Good Laboratory Practice (GLP) according to the pertinent Community directive
Going Beyond Counting First Authors in Author Co-citation Analysis
No full textThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Mitomycin C in highly myopic eyes - Author reply
No full textOphthalmology. 2005 Feb;112(2):208-18; discussion 219.
Mitomycin C modulation of corneal wound healing after photorefractive keratectomy in highly myopic eyes.
Gambato C, Ghirlando A, Moretto E, Busato F, Midena E.
SourceRefractive Surgery Service and Antimetabolite Therapy Research Unit, Department of Ophthalmology, University of Padova, Padova, Italy.
Abstract
PURPOSE: To evaluate the role of topical mitomycin C in corneal wound healing (CWH) after photorefractive keratectomy (PRK) in highly myopic eyes.
DESIGN: Prospective, double-masked, randomized clinical trial.
PARTICIPANTS: Seventy-two eyes of 36 patients affected by high (>7 diopters) myopia.
METHODS: In each patient, one eye was randomly assigned to PRK with intraoperative topical 0.02% mitomycin C application, and the fellow eye was treated with a placebo. Postoperatively, mitomycin C-treated eyes received artificial tears (3 times daily, tapered in 3 months), whereas the fellow eye was treated with fluorometholone sodium 2% and artificial tears (3 times daily, tapered in 3 months).
MAIN OUTCOME MEASURES: Uncorrected visual acuity (UCVA) and best-corrected visual acuity (BCVA), contrast sensitivity, manifest refraction, and biomicroscopy. Contrast sensitivity was determined using the Pelli-Robson chart. Corneal confocal microscopy documented CWH.
RESULTS: Mean follow-up was 18 months (range, 12-36). No side effects or toxic effects were documented. At 12-month follow-up examination, UCVAs (logarithm of the minimum angle of resolution) were 0.4+/-0.48 and 0.5+/-0.53 (P = .03) in mitomycin C-treated eyes and corticosteroid-treated eyes, respectively. At 1 year, corneal haze developed in 20% of corticosteroid-treated eyes, versus 0% of mitomycin C-treated eyes. At 12, 24, and 36 months, corneal confocal microscopy showed activated keratocytes and extracellular matrix significantly more evident in untreated eyes (Ps = 0.004, 0.024, and 0.046, respectively).
CONCLUSION: Topical intraoperative application of 0.02% mitomycin C can reduce haze formation in highly myopic eyes undergoing PRK.
Comment in
Ophthalmology. 2006 Feb;113(2):357; author reply 357-8
Dispelling the Myths Behind First-author Citation Counts
No full textWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
Exposition of marine copepods to organophosphorus xenobiotics: application of acetylcholinesterase biomarkers in the laboratory
No full textOrganophosphorus pesticides (OP) are dangerous xenobiotics for aquatic environments mainly because they can interact with all links of the food web inducing bioaccumulation and bioconcentration in organisms. In addition, they have an influence on the enzymes of the cholinergic system (acetylcholinesterase and pseudocholinesterase) of the organisms blocking their catalytic site and causing an excess of excitation of receptors for acetylcholine accumulation. The biomarkers, such as the evaluation of acetylcholinesterase (AChE) inhibition, provide an indication of the pollution level of the environment and are indicators of the ecotoxicological risk for exposed organisms. As small invertebrates are a fundamental link in the food web, the ecotoxicological risk evaluated on these organisms with the biomarker approach can be used as an early evidence of ecosystem damage. In this research copepods collected in the splashpools of the eastern coast of the Ligurian Sea and maintained in the laboratory were utilized as test-organisms. Aim of this work was to evaluate in copepods Tigriopus fulvus the effect of the exposition to the organophosphorus pesticide Malathion (Pestanalâ) on the activity of AChE
A Multi-Language Comparison of Influences on Author Verification using Character N-Grams
No full textWe create a new multi-language corpus for author verification based on Wikipedia talkpages, and evaluate the influence that differences in topic and time have on character n-gram author profiles. Topic alignment between two texts is found to increase author verification precision, and an authors writing style is found to change over time, but not more significantly after 3 years than after 1 year.Information ArchitectureWISElectrical Engineering, Mathematics and Computer Scienc
- …
