1,720,979 research outputs found
Environmental risk assessment of propranolol in the groundwater bodies of Europe
No full textA growing concern for contamination due to pharmaceutical compounds in groundwater is expanding globally. The β-blocker propranolol is a β-adrenoceptors antagonist commonly detected in European groundwater bodies. The effect of propranolol on stygobiotic species (obligate groundwater dweller species) is compelling in the framework of environmental risk assessment (ERA) of groundwater ecosystems. In fact, in Europe, ERA procedures for pharmaceuticals in groundwater are based on data obtained with surrogate surface water species. The use of surrogates has aroused some concern in the scientific arena since the first ERA guideline for groundwater was issued. We performed an ecotoxicological and a behavioural experiment with the stygobiotic crustacean species Diacyclops belgicus (Copepopda) to estimate a realistic value of the Predicted No Effect Concentration (PNEC) of propranolol for groundwater ecosystems and we compared this value with the PNEC estimated based on EU ERA procedures. The results of this study showed that i) presently, propranolol does not pose a risk to groundwater bodies in Europe at the concentrations shown in this study and ii) the PNEC of propranolol estimated through the EU ERA procedures is very conservative and allows to adequately protect these delicate ecosystems and their dwelling fauna. The methodological approach and the results of this study represent a first contribution to the improvement of ERA of groundwater ecosystems.Capsule: The study provides: i) the first ecotoxicological and behavioural data concerning a stygobiotic crustacean species exposed to a pharmaceutical compound; ii) a realistic estimate of the Predicted No Effect Concentration (PNEC) of propranolol to be used in groundwater environmental risk assessment procedure
A behavioural and MRI structural study of early stage 6-OHDA Parkinson's disease rat model
No full textSubchronic Effects of Tetrachloroethylene on Two Freshwater Copepod Species: Implications for Groundwater Risk Assessment
No full textAliphatic chlorinated hydrocarbons, notably tetrachloroethylene (also known as perchloroethylene [PCE]), are persistent, mobile, and toxic (PMT) and/or very persistent, mobile, and toxic (vPMT) groundwater pollutants, often exceeding safe drinking water thresholds. The present study delves into the groundwater risk assessment of PCE with a novel focus on the sensitivity of stygobitic species-organisms uniquely adapted to groundwater environments. Through a comparative analysis of the subchronic effects of PCE on the locomotion behavior of two copepod species, the stygobitic Moraria sp. and the nonstygobitic Bryocamptus zschokkei, we highlighted the inadequacy of the current European predicted-no-effect concentration of PCE for groundwater ecosystems. Our findings indicate significant behavioral impairments in both species at a concentration (32 ng/L PCE) well below the threshold deemed safe, suggesting that the current European guidelines for groundwater risk assessment may not adequately protect the unique biodiversity of groundwater habitats. Importantly, B. zschokkei demonstrated sensitivity to PCE comparable to or greater than that of the target stygobitic species, suggesting its utility as a substitute species in groundwater risk assessment. The present study adds to the limited research on the ecotoxicological sensitivity of groundwater species to PMT/vPMT chemicals and highlights the need for refined groundwater risk-assessment methodologies that consider the susceptibilities of stygobitic species. Environ Toxicol Chem 2024;00:1-13. (c) 2024 The Author(s). Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC
New electrolytes for high power Li-ion batteries : electrochemical stability, Li-ion insertion kinetics and corrosion inhibition properties
No full textA new generation of high power Li-ion batteries that avoid carbon as anodic material replacing it with the spinel Li4Ti5O12 has been studied in this work. For these new Li-ion cells new electrolyte compositions can be considered. The main work of this thesis was focused on the electrolyte. Electrochemical techniques such as Cyclic Voltammetry and Amperometry were used to characterize the behaviour of electrolytes containing LiSO3CF3 or LiN(SO2CF3)2 (LiTFSI) or LiN(SO2C2F5)2 (LiBETI) salts. It was confirmed that LiTFSI determines a severe corrosion of the aluminium current collector at potential around 3.7 V (vs. Li). A protective effect induced by solvents having a cyano-group has been shown. The increase in repassivation potential (ER) observed with nitriles is in the range 0.4-0.5 V, and the value diminishes with increasing the temperature. Based on the experimental observations made and information collected from the literature, a mechanism to explain the inhibiting properties of nitriles was proposed. This was based on the assumption that aluminium undergoing corrosion have highly reactive intermediates, e.g. Al+, capable of reducing the electrolyte. The extension of the experiments to prototype Li-ion cells demonstrated that corrosion inhibiting properties combine with superior Li-ion insertion kinetics. Prototype Li-ion cells were made using Swagelok-type cells. Tests of Li4Ti5O12/LiCoO2 cells were performed for high charge rate and under extensive cycling. Charge/discharge curves showed that the new electrolytes offer properties suitable for high power batteries. Particularly, electrolytes containing LiTFSI salt were found to be compatible with LiCoO2 cathode materials on an aluminium current collector under cycling of up to 4.15 V (vs.Li.) at ambient temperature. Electrochemical stabilities of some solvents from the lactone and nitrile families were studied as well as kinetics. Substitutions in the α and γ positions of the γ-butyrolactone (γ-BL) were not successful in increasing the electrochemical stability of the γ-BL. UVvis spectra as well as HPLC analyses on electrolyzed γ-BL/LBF4 electrolytes suggested that the electrochemical decomposition of γ-BL involves a complex mechanism. Likely the reactions: occurs 'in parallel', 'in sequence' and exhibits 'feedback'. Electrochemical stability of some nitriles tested: only oxidipropionitrile exhibited a resistance to oxidation higher than γ-BL. All the electrolytes under investigation showed higher currents on glassy carbon than on tin oxide electrodes. LiMn1.5Ni0.4Ti0.1O4 electrode for high voltage Li-ion battery were also tested. The use of cyclic voltammetry in combination with nano-composite TiO2 electrodes proved suitable for kinetics evaluation. The nature of the salts as well as the solvents provided an effect on the Li-ion insertion kinetics. The observed differences were explained by means of a computational approach (MESP) relating its results to the "hard soft/acid base" concept.LP
Comparison between tail suspension swing test and standard rotation test in revealing early motor behavioral changes and neurodegeneration in 6-OHDA hemiparkinsonian rats
Get PDFThe unilateral 6-hydroxydopamine (6-OHDA) model of Parkinson's disease (PD) is one of the most commonly used in rodents. The anatomical, metabolic, and behavioral changes that occur after severe and stable 6-OHDA lesions have been extensively studied. Here, we investigated whether early motor behavioral deficits can be observed in the first week after the injection of 6-OHDA into the right substantia nigra pars compacta (SNc), and if they were indicative of the severity of the dopaminergic (DAergic) lesion in the SNc and the striatum at different time-points (day 1, 3, 5, 7, 14, 21). With this aim, we used our newly modified tail suspension swing test (TSST), the standard rotation test (RT), and immunohistochemical staining for tyrosine hydroxylase (TH). The TSST, but not the standard RT, revealed a spontaneous motor bias for the 6-OHDA-lesioned rats from the day 1 post-surgery. Both tests detected the motor asymmetry induced by (single and repeated) apomorphine (APO) challenges that correlated, in the first week, with the DAergic neuronal degeneration. The described TSST is fast and easy to perform, and in the drug-free condition is useful for the functional assessment of early motor asymmetry appearing after the 6-OHDA-lesion in the SNc, without the confounding effect of APO challenges.peer-reviewe
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe 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
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
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