1,721,056 research outputs found
Solid-phase extraction of vanadium (V) from tea infusions and wines on immobilized nanometer titanium dioxide followed by ICP-OES analysis
No full textAbstract Nanosized titanium dioxide immobilized on silica gel was synthesized and used as
fixed-bed phase for V (V) pre-concentration, followed by inductively coupled plasma optical
emission spectroscopy (ICP-OES) analysis. Three different sorbents were prepared by sol-
gel method starting from a mixture of titanium isopropoxide, 2-propanol and water, and
characterized by X-ray powder diffraction (XRPD), scanning electron microscopy (SEM) and
BET analysis
Sunlight-promoted photocatalytic hydrogen gas evolution from water-suspended cellulose: a systematic study
No full textA comparsi between four different methods of sampling GSR from gunshot wounds in skin and bone: different applicability and reliability
No full textBackground and Aims: the sampling procedures of gunshot residues (GSR) on entry wounds is crucial and still a precise agreement on sampling procedures is yet lacking. Thus, an experimental study on GSR sampling was performed.
Materials and Methods: a total of 20 samples (ten of pig skin free of fur and ten of bovine ribs without soft tissues) were shot once at a firing ground, with a semiautomatic pistol with 9x21 mm projectiles (full-metal-jacketed bullets). Moreover, two unshot samples (one pig skin and one bovine rib) were kept as controls. Samples were fired with a near-contact range and a range of about 40 cm, keeping the muzzle perpendicular to the surface of the sample. The periphery of the wound was divided into 4 wedges and collection of GSR was performed with graphite tape, white canvas tape, transparent adhesive tape and cotton swabs soaked in alcohol, one for each centimeter from the wound edges, up to a distance of 3 cm. The same samplings were performed on controls. Samples were treated with 1 ml 30% ultrapure nitric acid, diluted to 10 ml with MilliQ water, filtered with 0.45 micron Nylon filter and each sample was analyzed with ICP-OES (for Ba, Pb), ICP-MS (more sensitive for Sb, Pb, Cu) and GC-MS (for organic elements, usually present along with inorganic elements: i.e. ethyl centralite, phthalates), after the samples were treated with isopropyl alcohol (1 ml) and diluted to 5 ml with acetone. Moreover, two samples of shot bovine ribs (one with near-contact range, one with distant range) were also analyzed by SEM-EDX to identify GSR by drying the sample in vacuo.
Results: First results showed the stub method with cotton swabs as best sampling procedure, since this technique enabled the highest amounts of residues to be gathered, and blank samplings showed higher purity with less interference by contaminants; the highest amount of metals were detected within the first 2-3 cm around the wound with near-contact ranges, while according to the results provided by the direct analysis with SEM in dried samples, constant concentration within 3-4-5 cm were detected with distant range. In all cases, stub and bones did not interfere with the element determination, as showed by blanks proofs. The determination of the element ratio (Cu/Pb, Sb/Pb) in most cases provided more reliable results and should thus be considered a better choice than the determination of single elements, since contaminations were evidenced and the elements' ratio in the bullets are quiet constant. The complementary combination of the methods used (ICP-OES, ICP-MS and GC-MS) provided an accurate assessment of the type of residues and concentrations, even though ICP-MS showed the highest sensitivity in the detection of inorganic metallic residues than ICP-OES.
Conclusions: The study shows the importance of the sampling procedures in case of gunshot wounds: from a quali-quantitative point of view, cotton swabs appeared to be the best sampling procedure, and the combination between ICP-MS and GC-MS provided a reliable assessment of the type, amounts and distribution of GSR
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe 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
Full text link“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
Full text linkWe 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
Dispelling the Myths Behind First-author Citation Counts
Full text linkWe 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
Glucocorticoids in Freshwaters: Degradation by Solar Light and Environmental Toxicity of the Photoproducts
Full text linkThe photodegradation process of seven glucocorticoids (GCs), cortisone (CORT), hydrocortisone (HCORT), betamethasone (BETA), dexamethasone (DEXA), prednisone (PRED), prednisolone (PREDLO) and triamcinolone (TRIAM) was studied in tap and river water at a concentration close to the environmental ones. All drugs underwent sunlight degradation according to a pseudo-first-order decay. The kinetic constants ranged from 0.00082 min−1 for CORT to 0.024 min−1 for PRED and PREDLO. The photo-generated products were identified by high-pressure liquid chromatography coupled to electrospray ionization tandem mass spectrometry (HPLC-ESI-MS/MS). The main steps of the degradation pathways were the oxidative cleavage of the chain 17 for CORT, HCORT and the rearrangement of the cyclohexadiene moiety for the other GCs. The acute and chronic toxicity of GCs and of their photoproducts was assessed by the V. fischeri and P. subcapitata inhibition assays. The bioassays revealed no significant differences in toxicity between the parent compounds and their photoproducts, but the two organisms showed different responses. All samples produced a moderate acute toxic effect on V. fisheri and no one in the chronic tests. On the contrary, evident hormesis or eutrophic effect was produced on the algae, especially for long-term contact. Keywords: glucocorticoids; solar light degradation; freshwater pollution; biotoxicity tests 1
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