1,720,969 research outputs found
Monitoraggio ambientale e biologico nei gestori di carburanti della provincia di Treviso.
No full textDeterminazione della ciclofosfamide su superfici e nelle urine mediante gas cromatografia-spettrometria di massa
No full textAssessment of exposure to oak wood dust using gallic acid as a chemical marker.
No full textObjectives: The American Conference of Governmental Industrial Hygienists (ACGIH) has classified oak dusts as human carcinogens (A1), based on increased sinus and nasal cancer rates among exposed workers. The aims of this study were to investigate the use of gallic acid (GA) as chemical marker of occupational exposure to oak dusts, to develop a high-performance liquid chromatography–diode array detector (HPLC–DAD) method to quantify it, and to apply the method in the analysis of oak dust samples collected in some factories.Methods: A high performance liquid chromatography (HPLC) method was developed to detect GA in oak wood dust. The method was tested on field, and GA was extracted from oak wood dust sampled in the air of five wood-working plants where only oak wood is used. Results: A total of 57 samplings was taken in the dust concentration range 0.271-11.138 mg/m3. Five of these exceeded the Italian threshold limit value of 5 mg/m3, and 30 exceeded the ACGIH TLV of 1 mg/m3. GA concentrations were in the range 0.017-4.178 μg/m3. The total oak dust sampled was correlated with GA contents with a coefficient of 0.95. Conclusions: The GA in tannic extracts of oak wood turned out to be specific for this type of wood, showing that its concentration in wood dust sampled in the work environment is useful in assessing true exposure to carcinogenic oak dust
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
Correlation between environmental and biological monitoring of exposure to benzene in petrochemical industry operators
Get PDFAbstract
The present work was aimed to study in petrochemical industry operators the correlation, if any, between environmental exposure to low levels of benzene and two biological exposure indexes in end-shift urine, i.e. trans, trans-muconic acid (t,t-MA) and S-phenylmercapturic acid (SPMA). Exposure to benzene was assessed in 133 male subjects employed in outdoor operations in a petrochemical plant, using personal passive-diffusive air samplers worn at the breathing zone; adsorbed benzene was determined by GC-FID analysis. S-PMA was determined by a new HPLCMS/MS method, after (quantitative) acidic hydrolysis of the cysteine conjugate precursor. t,t-MA was measured by an HPLC-UV method. Smoking habits were assessed by means of a self-administered questionnaire. Both environmental and biological monitoring data showed that benzene exposure of petrochemical industry operators was low (mean values were 0.014ppm, 101mug/g creat, and 2.8mug/g creat, for benzene, t,t-MA, and S-PMA, respectively) if compared with the ACGIH limits. Cigarette smoking was confirmed to be a strong confounding factor for the urinary excretion of both metabolites: statistically significant increases of t,t-MA and S-PMA levels were recorded in smokers when compared to non-smokers (p<0.0001). The best correlation found was that between exposure to benzene and S-PMA levels, particularly in non-smokers. This was partly due to the hydrolysis of the S-PMA precursor N-acetyl-S-(1,2-dihydro-2-hydroxyphenyl)-l-cysteine, a crucial step of the new analytical method used, which indeed reduced the variability of the results by means of an improved standardization of this critical preanalytical factor. A weaker correlation was found between exposure to benzene and t,t-MA, possibly explained by the fact that the latter is also a metabolite of sorbic acid, a common diet component. In summary, even at such low levels of exposure, urinary metabolites proved to be a useful tool for assessing individual occupational exposure to benzene, S-PMA appearing to be a more specific biomarker than t,t-MA, particularly in non-smokers
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
Biomonitoring occupational sevoflurane exposure at low levels by urinary sevoflurane and hexafluoroisopropanol.
No full textThis study aimed to correlate environmental sevoflurane levels with urinary concentrations of sevoflurane (Sev-U) or its metabolite hexafluoroisopropanol (HFIP) in order to discuss the main issues relating to which biomarker of sevoflurane exposure is best, and possibly suggest the corresponding biological equivalent exposure limit values. Individual sevoflurane exposure was measured in 100 healthcare operators at five hospitals in north-east Italy using the passive air sampling device Radiello®, and assaying Sev-U and HFIP concentrations in their urine collected at the end of a session in the operating room. All analyses were performed by gas chromatography-mass spectrometry. Environmental sevoflurane levels in the operating rooms were also monitored continuously using an infrared photoacoustic analyzer. Our results showed very low sevoflurane individual exposure levels, generally below 0.5 ppm (mean 0.116 ppm; range 0.007-0.940 ppm). Sev-U and HFIP concentrations were in the range of 0.1-17.28 μg/l and 5-550 μg/l, respectively. Both biomarkers correlated statistically with the environmental exposure levels (Sev-U, r=0.49; HFIP, r=0.52), and with each other (r = 0.27), albeit with fairly scattered values. Sev-U values seem to be influenced by peaks of exposure, especially at the end of the operating-room session, whereas HFIP levels by exposure on the previous day, the data being consistent with the biomarkers’ half-lives (2.8 and 19 h, respectively). According to our results, both Sev-U and HFIP are appropriate biomarkers for assessing sevoflurane exposure at low levels, although with some differences in times/patterns of exposure. More work is needed therefore to identify the best biomarker of sevoflurane exposure and the corresponding biological equivalent exposure limit value
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
Indicatori biologici nella valutazione dell’esposizione a bassi livelli di benzene: esperienza in una raffineria
No full textThe aim of this study was to assess benzene exposure in a refinery through techniques of environmental and biological monitoring dosing airborne benzene, urinary benzene (BU), t,t-muconic acid (t,t-MA) and S-phenylmercapturic acid (S-PMA). It was also evaluated the influence of genetic polymorphisms on biomarkers of exposure. The study involved 146 exposed subjects and 25 controls. Benzene exposure was measured using a diffusive sampler Radiello®; the analysis was performed by GC-FID. UB, S-PMA and t,t-MA were determined respectively by HS-GC/MS, HPLC-MS/MS and HPLC-UV. The GSTT1 and GSTM1 polymorphisms were detected on mouth mucosa cells by “polymerase chain reaction”-based methods. The personal exposure to benzene was very low (mean 0.033 mg/m3, range <0.002-0.529 mg/m3) but significantly higher (p <0.05) than in the control group (mean 0.012 mg/m3, range <0.002-0.016 mg/m3). Low exposure was also confirmed by the levels of biomarkers (BU: mean 0.57 μg/l, range 0.01-4.79 μg/l; t,t-MA: mean 80.2 μg/g creatinine, range <3.0-946.2 μg/g creatinine; S-PMA: mean 4.15 μg/g creatinine range <0.1-80.1 μg/g creatinine). The analysis of GSTT1 genotype associated with post-shift urinary excretion of S-PMA showed that the efficiency of biotransformation of benzene in the S-PMA is lower in subjects with GSTT1 null allele compared with non-null (p <0.05)
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