1,720,983 research outputs found
Intrinsic and environmental effects in the structure and magnetic properties of organic molecular magnets: Bis(imino)nitroxide
No full textStress corrosion cracking of tinplated cans for conserved tuna in oil
No full textStress Corrosion Cracking (SCC) is induced by the combined influence of tensile stress and a corrosive environment. SCC can occur for specific metal/environment coupling, and its effect is higher than the sum of environmental corrosiveness and stress state. Usually, the metal surface remains almost unattacked, but with fine cracks penetrating into the material. These cracks can have intergranular or transgranular morphology. SCC is classified as a catastrophic form of corrosion, since the detection of such fine cracks can be very difficult and the damage is not easily predicted. In recent literature, several SCC cases occurring in tinplate cans for the conservation of highly proteic food (meat, tuna or petfood) are reported. In these cases, the specific SCC damage can be very dangerous due to fine cracks that can pass through the can wall, causing the air ingress. The present work is focused on the analysis of stress corrosion damage suffered by two different types of tinplate cans (called A and B) for oil-conserved tuna. Tinplated steel cans came from two different producers, and also the tuna meat came from different companies. Metallic cans are usually produced using low carbon steel, tinplated and then coated with epoxyphenolic resin. From thin strips, the cans are often produced by welding. After welding, both internal and external welding regions are re-protected with epoxyphenolic film; the cans are then filled with tuna meat, filled with oil under low pressure, and finally closed and sterilized around 115-120°C. In both examined cases, fine and branched SCC cracks were observed close to the welding regions. A deep microscopic analysis, performed by Scanning Electron Microscope (SEM) equipped with a energy dispersive system (EDS), highlighted the presence of resin delamination in regions close to SCC cracks. Moreover, inside the microcracks, a mixture of corrosion products and phosphates was detected. A chemico/physical analysis was performed on liquid phases contained in the cans. A large amountof water was present in both can types, higher for sample B than A. Moreover, the chemical analysis of the aqueous phases showed a massive presence of phosphates and bicarbonates, together with chlorides. The typical pH value was around 5.8. Experimental results are discussed in order to explain the occurrence of SCC in the carbon steel. First of all, the occurrence of oil-water separation inside the can is necessary to induce corrosive phenomena. Moreover, the only region prone to SCC is near the welding, as a consequence of residual stresses induced by the thermal treatment. In these regions a water phase comes in contact with the steel surfaces whatever discontinuities are present in the protective epoxy-phenolic deposit. Among possible chemical environment carrying to SCC on low carbon steel, phosphates in deareated water are the most probable in this case. Some experimental evidence suggest that phosphates promote a polarization inversion between steel and tin. A possible way to control SCC damage in these applications is the use of more continuous, thicker and more protective laquers on welding regions, such as powder layers (around 80 m in thickness) obtained with thermoplastic modified polyesters
Corrosione sotto sforzo su conserve di tonno sott'olio in banda stagnata
Full text linkNel presente lavoro sono stati analizzati alcuni casi di corrosione sotto sforzo (Stress Corrosion Cracking, SCC)su scatolette metalliche in banda stagnata per la conserva di tonno sott’olio. I contenitori metalliciprovenivano da due diversi fabbricanti di barattoli, con carni di diversi operatori del settore alimentare.In entrambi i casi sono state osservate microcricche fini e ramificate da SCC a ridosso delle regioni disaldatura. Dalle analisi chimiche del liquido associato ai prodotti sono state rilevate quantità sensibili di faseacquosa ed elevate concentrazioni di fosfati e cloruri, assieme a concentrazioni minori di bicarbonati e solfati.Gli esami in microscopia elettronica in scansione (SEM/EDS) hanno evidenziato all’interno delle lesionila presenza di prodotti di corrosione dell’acciaio frammisti a quantità sensibili soprattutto di fosfati.Tra i fattori scatenanti l’innesco della SCC hanno sicuramente importanza la separazione di fase acquosae le autotensioni in regione di saldatura. Occorre però anche una specificità dell’accoppiamento metalloambientee, in tal senso, l’ipotesi più probabile è l’abbondante presenza di fosfati in un ambiente acquosopraticamente deaerato. Da quanto osservato, questi anioni sembrano indurre anche inversione di polaritàtra acciaio al carbonio e deposito di stagno. Nel lavoro sono infine dati suggerimenti per minimizzarel’insorgenza di tali danneggiamenti
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
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
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