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Comparison of the release of elements from enamel into food with that into food simulants under different temperature-time conditions
No full textIm Rahmen dieser Arbeit wurde das Freisetzungsverhalten von Elementen aus Emaille unter verschiedenen Zeit-Temperatur-Bedingungen in Lebensmittelsimulanzien mit dem in Lebensmittel verglichen. In der Emaille-Norm DIN EN ISO 4531:2022-08[1] sind die Bedingungen und Lebensmittelsimulanzien festgelegt, mit welchen Freisetzungsexperimente normgemäß durchgeführt werden. Die meisten der bislang durchgeführten Überprüfungen von emaillierten Bedarfsgegenständen folgen der Richtlinie 84/500/EWG des Europäischen Rates zu Keramik mit Lebensmittelkontakt[2] oder den Richtlinien des Europarates zu Metallen und Legierungen[3]. Die darin enthaltenen verschiedenen Simulanzien und Freisetzungsbedingungen erschweren den Vergleich der Ergebnisse. Zudem beruht die Wahl der verwendeten Simulanz nicht auf vergleichbaren Versuchen mit Lebensmitteln, sondern stammt aus Übertragungen von bestehenden Richtlinien, wie beispielsweise der 84/500/EWG oder der Verordung (EU) Nr. 10/2011 der Kommission über Materialien und Gegenstände aus Kunststoff, die dazu bestimmt sind, mit Lebensmitteln in Berührung zu kommen[4]. Um bessere Vergleichbarkeit zu schaffen und die Simulanz mit den Bedingungen zu finden, die sich am besten eignet für die Freisetzung von Elementen aus Emaille, wurden in dieser Arbeit erste Versuche unternommen, das Freisetzungsverhalten in verschiedenen Simulanzien und Bedingungen zu untersuchen. Für die Durchführung der Freisetzungsversuche wurden genormte Migrationszellen verwendet und drei aufeinanderfolgende Freisetzungen durchgeführt, um Mehrfachgebrauch zu simulieren. Als Simulanzien wurden 3%-ige Essigsäure, 0.5%-ige Zitronensäure und angesäuertes künstliches Leitungswasser verwendet und mit den Ergebnissen der Freisetzungsversuche in angesäuertem Tomatensaft und Sauerkrautsaft verglichen. Als Analyten wurden Lithium, Aluminium, Chrom, Mangan, Eisen, Cobalt, Nickel, Kupfer, Zink, Barium und Blei betrachtet, die mittels ICP-MS ausgewertet wurden. Der Vergleich der beiden verwendeten Temperatur-Zeit-Bedingungen (24 h bei 40 °C und 2 h bei 70 °C) ergab einen klaren Trend. Wie erwartet, nahm die Analytkonzentration mit den Freisetzungen ab. Zunächst schien die kühlere Bedingung (24 h bei 40 °C) die höheren Ergebnisse zu erzielen, jedoch hätten unter Annahme einer Kinetik erster Ordnung vollständig vergleichbare Ergebnisse bei 3 h bei 70 °C erzielt werden können. Demnach sind die niedrigeren Ergebnisse für die Bedingungen von 2 h bei 70 °C erwartbar. Beim Vergleich der Simulanzien mit den Lebensmitteln konnte festgestellt werden, dass das angesäuerte künstliche Leitungswasser in den meisten Fällen die Ergebnisse liefert, die am nächsten an die der Lebensmittel herankommt. In einigen Fällen zeigt sich die 3%-ige Essigsäure geeigneter. Die 0.5%-ige Zitronensäure erzielte deutlich überschätzte Ergebnisse im Vergleich zu den Lebensmitteln. Mit den durchgeführten Versuchen trägt diese Arbeit dazu bei, das Freisetzungsverhalten von Elementen aus Eaille besser zu verstehen und eine geeignete Simulanz, sowie Freisetzungsbedingung zu finden, die realistische worst-case-Szenarien imitiert und die Freisetzung der Elemente in Lebensmittel leicht überschätzt, sodass der Verbraucherschutz gewährleistet ist.Within the scope of this work, the release behaviour of elements from enamel under different time-temperature conditions into food simulants was compared with that into food. The enamel standard DIN EN ISO 4531:2022-08[1] specifies the conditions and food simulances with which release experiments are carried out. Most of the tests conducted to date on enamelled products follow the European Council Directive 84/500/EEC on food contact ceramics[2] or the Guidelines of the council of europe on metals and alloys[3]. The different simulants and release conditions contained therein make it difficult to compare the results. In addition, the choice of simulant used is not based on comparable tests with foodstuffs, but originates from transfers from existing guidelines such as 84/500/EEC or Commission Regulation (EU) No. 10/2011 on plastic materials and articles intended to come into contact with food[4]. In order to create better comparability and to find the simulant with the conditions that are best suited for the release of elements from enamel, the release behaviour in various simulants and conditions was investigated in this work. Standardised migration cells were used to carry out the release and three migrations took place in succession to simulate multiple use. As simulants, 3% acetic acid, 0.5% citric acid and acidified artificial tap water were used and the results compared to the release experiments with acidified tomato juice and sauerkraut juice. The analysed elements were lithium, aluminium, chromium, manganese, iron, cobalt, nickel, copper, zinc, barium and lead, which were evaluated using ICP-MS. The comparison of the two temperature-time conditions used (24 h at 40 °C and 2 h at 70 °C) revealed a clear trend. As expected, the analyte concentration decreased in each successive migration. At first glance the cooler condition (24 h at 40 °C) surprisingly yielded higher migration levels for the investigated elements, however, assuming a first order kinetic fully comparable results would have been achieved only with 3 h at 70 °C. Thus, the lower results at 2 h, 70 °C were expectable. When comparing the simulants with the foodstuffs, it was found that in most cases the results with acidified artificial tap water came closest to those of the foodstuffs. In some cases, the 3% acetic acid resulted in more realistic migration levels. The 0.5% citric acid gives clearly overestimated results in comparison to those with food stuffs. With the experiments carried out, this work contributes to a better understanding of the release behaviour of elements from enamel and to finding a suitable simulant and release condition that mimics realistic worstcase scenarios and slightly overestimates migration into foods so that consumer protection is guaranteed
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
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
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
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe 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
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
Author Under Sail The Imagination of Jack London, 1893-1902
No full textIn Author Under Sail, Jay Williams offers the first complete literary biography of Jack London as a professional writer engaged in the labor of writing. It examines the authorial imagination in London's work, the use of imagination in both his fiction and nonfiction, and the ways he defined imagination in the creative process in his business dealings with his publishers, editors, and agents. In this first volume of a two-volume biography, Williams traverses the years 1893 to 1902, from London's "Story of a Typhoon" to The People of the Abyss. The Jack London who emerges in the pages of Author Under Sail is a writer whose partnership with publishers, most notably his productive alliance with George Brett of Macmillan, was one of the most formative in American literary history. London pioneered many author models during the heyday of realism and naturalism, blurring the boundaries of these popular genres by focusing on absorption and theatricality and the representation of the seen and unseen. London created an impassioned, sincere, and extremely personal realism unlike that of other American writers of the time. Author Under Sail is a literary tour de force that reveals the full range of London as writer, creative citizen, and entrepreneur at the same time it sheds light on the maverick side of machine-age literature.Intro -- Title Page -- Copyright Page -- Dedication -- Contents -- Acknowledgments -- Introduction -- 1. Spirit Truth -- 2. From Absorption to Theatricality and Back Again -- 3. "I Will Build a New Present" -- 4. Sons as Authors -- 5. Fathers as Publishers -- 6. The Daughter as Author -- 7. Lovers as Authors -- 8. At Sea with the Family -- 9. Yellow News, Yellow Stories -- 10. The Return Home -- Notes -- Bibliography -- Index -- About Jay WilliamsIn Author Under Sail, Jay Williams offers the first complete literary biography of Jack London as a professional writer engaged in the labor of writing. It examines the authorial imagination in London's work, the use of imagination in both his fiction and nonfiction, and the ways he defined imagination in the creative process in his business dealings with his publishers, editors, and agents. In this first volume of a two-volume biography, Williams traverses the years 1893 to 1902, from London's "Story of a Typhoon" to The People of the Abyss. The Jack London who emerges in the pages of Author Under Sail is a writer whose partnership with publishers, most notably his productive alliance with George Brett of Macmillan, was one of the most formative in American literary history. London pioneered many author models during the heyday of realism and naturalism, blurring the boundaries of these popular genres by focusing on absorption and theatricality and the representation of the seen and unseen. London created an impassioned, sincere, and extremely personal realism unlike that of other American writers of the time. Author Under Sail is a literary tour de force that reveals the full range of London as writer, creative citizen, and entrepreneur at the same time it sheds light on the maverick side of machine-age literature.Description based on publisher supplied metadata and other sources.Electronic reproduction. Ann Arbor, Michigan : ProQuest Ebook Central, YYYY. Available via World Wide Web. Access may be limited to ProQuest Ebook Central affiliated libraries
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