1,720,972 research outputs found
Gli usi nella Convenzione di Vienna sulla vendita internazionale di beni mobile
No full textIl presente lavoro si occupa della rilevanza degli usi e delle prassi contrattuali nei contratti di vendita internazionale di beni mobili alla luce della disciplina posta dalla Convenzione di Vienna del 1980 sulla vendita internazionale di beni mobil
Corrosion inhibition of steel in chloride-containing alkaline solutions
No full textSome organic inhibitors of steel corrosion in saturated calcium hydroxide solutions containing 0.1 M chlorides were investigated to elucidate their interactions with the steel surface. The compounds studied were dicyclohexylammonium nitrite (DCHAMN), dicyclohexylamine (DCHA), sodium β-glycerophosphate (GPH) and 5-hexyl-benzotriazole (C6BTA). Sodium nitrite (SN) was also studied as a reference. The techniques applied were electrochemical impedance spectroscopy (EIS), polarization curves, cyclic voltammetry (CV) and Fourier transform infrared (FTIR) spectroscopy. FTIR spectra showed that DCHAMN, DCHA, GPH and C6BTA interact with the steel surface by chemisorption and some information about the mechanism also emerged. From DCHAMN solution, DCHA chemisorption is induced by slow salt hydrolysis. CV tests show that, among chemisorbed substances, only GPH avoids chloride penetration on cycling, most likely due to a quick chemisorption, while DCHAMN can only enlarge the passive potential range. Addition of SN also prevents chloride attack on cycling. Twenty days of immersion in inhibited solutions revealed that, besides SN, GPH and DCHAMN also form an impervious surface film on steel, which blocks any localized corrosion attack, whereas in the case of DCHA and C6BTA solutions, pitting corrosion is slowed down, but not avoided. DCHAMN exhibits the highest inhibiting efficiency at long immersion times, as a result of a synergetic inhibitive action which develops between nitrite and chemisorbed DCHA
Inhibition of acid corrosion of nickel by acetylenic alcohols
No full textThe inhibition of nickel corrosion by means of 3-methyl-1-butyne-3-ol (H), its halo-derivatives and 1-octyn-3-ol (OCT) has been studied by solution analysis, polarization curve recording and electrochemical impedance spectroscopy, in deaerated 1N HCl or H2SO4 solutions, at 70 °C. It has been found that the inhibiting effects of the tested additives are similar to those determined in the case of iron acid corrosion. It is assumed that on both metals they form polymeric films with the same mechanism. These compounds are more efficient in the hydrochloric acid solution than in the sulphuric one. OCT is more efficient than H; however the efficacy of the latter molecule can be improved by the substitution of the acetylenic hydrogen atom with halogen atoms, chiefly iodine, that affords an high inhibiting action on the anodic reaction
Lodi fa scuola fra "Pac" via web e voti ai dirigenti - Mezzi e strumenti adottati dal sistema di programmazione, controllo e valutazione dell'Asl di Lodi
No full textInfluence of CeALO3 nanoparticles on the performances of silane coatings for AZ31 alloy
No full textThis research investigates the influence exerted by CeAlO3 nanoparticle additions on the protective performances of some silanes (3-mercapto-propyl-trimethoxy-silane, PSH; vinyltrimethoxy-silane, VS; 3-(trimethoxysilyl)propyl-methacrylate, PSMA; 1,2-bis(triethoxysilyl)-ethane, BTSE), used as conversion coatings for AZ31 Mg alloy. Among the tested silanes, PSH is the most efficient one, followed by the vinyl derivatives (VS and PSMA) and finally by BTSE. In fact, in comparison to the other silanes, PSH determines a more significant reduction in the cathodic and anodic polarization currents and maintains a higher degree of protection for at least 24 h. Afterwards, it gradually loses its protective effects. Conversely, VS, BTSE, PSMA conversion coatings allow the onset of significant corrosion rates within a few hours. In all silane coatings, the addition of CeAlO3 nanoparticles increases both the coating protectiveness and the persistence of the protective action. In particular, the higher the silane coating performance, the greater the enhancing effect of the nanoparticles. Thus, CeAlO3 nanoparticles particularly improve the protectiveness of PSH conversion coating, which displays an inhibiting efficiency of over 99%, after 168 h of immersion in 0.1 M NaCl solution. On this coating type containing nanoparticles, the electrochemical impedance spectra (EIS) and the scanning electron microscopy (SEM) observations evidence an increase in the layer thickness from 3.5±0.5 μm to 5.6±0.6 μm and a decrease in the layer porosity. Therefore, the nanoparticles induce slower diffusion processes, which particularly slow down the anodic reaction, so hindering the overall corrosion process
Organic films for protection of copper and bronze against acid rain corrosion
No full textIn this paper, the anticorrosive effects of surface films formed on copper and bronzes by different organic inhibitors (mainly benzotriazole derivatives) are evaluated. Several alloys, nominally similar in composition to ancient artistic bronzes, were studied in comparison with copper. The protective efficiency of the organic coatings was tested by electrochemical ac and dc measurements performed both in acid and neutral rain. The experimental data show that benzotriazole derivatives with a long aliphatic chain form thin and very protective films on copper. The presence of the alloying elements (e.g. Sn, Zn, Pb) and multiphasic structures decrease the organic film performances. Nevertheless, among the compounds used, the most efficient, 5-octyl-1,2,3-benzotriazole (C8), seems to be a promising coating in the bronze conservation field. (C) 2003 Elsevier Ltd. All rights reserved
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
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