1,720,990 research outputs found
A DSC study on the interaction between tricresyl phosphates (TCP) and phospholipid liposomes.
No full textThis paper reports on the DSC and Raman measurements of hydrated multilamellar dimyristoylphosphatidylcholine (DMPC) and dimyristoylphosphatidylethanolamine (DMPE) liposomes in the presence of raw tricresyl phosphates (TCP) and pure tri-o-cresyl phosphate (TOCP). The results on TCP/DMPC and TOCP/DMPC liposomes showed no significant differences. Both tge Tm decrease and ΔT1/2 increase, obtained by increasing the relative amount of TCP with respect to liposomes, suggested that the hydrophobic core is strongly affected by the presence of TCP molecules, whose deep penetration into the bilayer is prevented by the polar interactions between the P=O group of the TCP molecules and the polar head on DMPC. On the contrary, the TCP/DMPE and TOCP/DMPE systems showed a phase segregation that takes place in the presence of a very small amount of TCP, and occurs somewhat more easily in the presence of TOCP than of raw TCP. Both TCP and TOCP molecules interact mainly with the outer face of the bilayer and only secondly affect the hydrophobic core of membranes
Copper(II)-Quercitin complexes in aqueous solutions: spectroscopic and kinetic properties.
No full textQuercetin (Querc), one of the most common dietary flavonols, was investigated in the presence of Cu(II) ions under basic conditions by different techniques in order to obtain some elucidation on the mechanism of its beneficial action against free radical-mediated damage.
The spectroscopic studies (UV/Vis, Raman and IR) were useful to assess the relevant interaction of Querc with Cu(II) ions, the chelation sites and the dependence of the complex structure from the metal/ligand ratio. In the presence of a slight excess of the ligand (0.5 M/L) Querc acts as a bidentate ligand trough the catechol moiety on B ring. At M/L>1 the metal interaction also involves the CO group and a close hydroxyl group. Thermogravimetric analysis confirmed the stoichiometry of the proposed complexes.
Information on the reactivity of the Cu(II) chelates towards oxidizing radicals (OH, and ) were obtained by the pulse radiolysis data. The chelates appear to fast react with these oxidizing radicals, giving rise to intermediates transients, namely resonance-stabilised phenoxyl radicals.
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Considerazioni sulla sorveglianza passiva della West Nile Disease negli equidi. L’esperienza dell’Emilia-Romagna nel triennio 2008-2010
Full text linkLa West Nile Disease (WND) è considerata in Italia una zoonosi riemergente in seguito alla ricomparsa sul territorio nazionale nell’estate del 2008, a distanza di 10 anni dal primo episodio di
malattia registrato in Toscana (Macini et al. 2008). Il West Nile Virus (WNV) si mantiene in natura grazie ad un ciclo che coinvolge gli uccelli
e le zanzare, tuttavia diversi mammiferi come l’uomo e il cavallo possono infettarsi manifestando generalmente sintomi simil-influenzali e in alcuni casi anche gravi meningoencefaliti.
L’obiettivo principale della sorveglianza veterinaria è la rilevazione precoce della circolazione virale al fine di adottare misure di prevenzione dell’infezione nel cavallo e nell’uomo. Uno degli
strumenti più efficaci a questo scopo è la valutazione dello stato clinico dei cavalli di proprietà, mirata alla segnalazione di casi sospetti da
sottoporre ad accertamenti diagnostici (OM 5/11/2008). Sono state esaminate le schede anamnestiche relative ai casi clinici confermati
di WND nel cavallo, riscontrati in Emilia-Romagna nel corso del triennio 2008-2010. Il quadro clinico è risultato assai variabile e
aspecifico confermando la necessità di ricorrere a specifici test di laboratorio per giungere alla diagnosi. Una maggiore informazione e sensibilizzazione dei veterinari operanti nel settore ippiatrico renderà più efficiente questo sistema di sorveglianza individuando prontamente nuovi casi sul territorio.
L’obiettivo di questo articolo è mettere a disposizione dei veterinari libero-professionisti alcuni strumenti diagnostici utili al riconoscimento della patologia neurologica e le modalità di segnalazione dei sospetti clinici di WND nel cavall
Raman and pulse radiolysis studies of the antioxidant properties of quercetin: Cu(II)-chelation and oxidizing radical scavenging.
No full textQuercetin (Querc), a pentahydroxyflavonol, is suggested to give protection to living organisms by both direct scavenging of free radicals and metal chelation. The scavenging ability of Querc towards oxidizing radicals, such as OH, N3 and NO2 , was evaluated by pulse radiolysis studies in aqueous solutions at different pH. Phenoxyl radicals are the final transient products and are formed either by water elimination from OH-adducts or by one-electron transfer from the deprotonated OH groups. Their formation rate is strongly affected by pH and reaches the maximum values in alkaline medium. The Raman and IR spectra were useful to assess the relevant interaction of Querc with Cu(II) ions, which play an important role in the metal-catalysed generation of reactive oxygen species. Depending on pH and the metal-to-ligand ratio, the different chelating sites of Querc change their ability to complex copper ions. Under neutral conditions, the 5-OH group of ring A and CO-4 of ring C have a chelating power superior to that of the catechol group (ring B), whereas the complexation in alkaline medium occurs in the reverse order. In addition, experiments with Querc and Zn(II) ions, carried out at basic pH in order to verify the possible Cu(II)-catalysed oxidation of the ligand, indicated the absence of the above process. Copyright © 2005 John Wiley & Sons, Ltd
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
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