When Glass and Metal Corrode Together,V: Sodium Copper Formate     

Andrea Fischer  Gerhard Eggert  Robert Dinnebier  Tomče Runčevski 《文物保护研究》2018,63(6):342-355

A sodium copper formate, first described in 2002, can also form on copper alloys with sodium originating from soda glass hydrolysis. The frequent occurrence (50% of 250 cases of glass-induced metal corrosion) is due to the presence of formaldehyde emissions in storage and its direct reaction to formate in the alkaline surface films. The compound can be produced without the presence of acetate when chalconatronite or metal coupons immersed in soda solution are exposed to formaldehyde vapours. The crystal structure, derived from X-ray powder diffraction, yielded the sum formula Cu₄Na₄O(HCOO)₈(OH)₂·4H₂O. Except for the absence of acetate in the structure, this is in good agreement with the 2002 publication. To assess which kind of combined glass/metal objects are affected, a number of large museum collections were surveyed. Sodium copper formate was detected as a corrosion product using mainly micro-Raman spectroscopy, for instance, on 18 painted Limoges enamels, eight glass vessels with metal mountings, glass beads on metal wire from 11 bridal crowns, nine Christmas tree balls with wire decoration, 40 pieces of jewellery with glass gems, three daguerreotypes, and one miniature with cover glasses.  相似文献   

Another Bridge Across the Access to Justice Gap: LII's Virtual Reference Desk     

Charlotte D. Schneider 《Legal Reference Services Quarterly》2017,36(2):85-102

The Legal Information Institute (LII) has been at the forefront of access to justice for 25 years as the first organization to publish online the United States Code. More than just publishing the law online, the LII has been the leader in helping people find and understand the law since 1992, through innovative technologies they've created or employed for use with their collections and through partnerships with other like-minded organizations, groups, and individuals. Two decades later, the LII was inspired to help more people trying to find and understand the law. This summer will mark the third anniversary of the LII's virtual Reference Desk.  相似文献   

Copper(II) hydroxide on artefacts: Corrosion,conservation, colourants     

Britta Schmutzler  Gerhard Eggert  Charlotte F. Kuhn-Wawrzinek 《文物保护研究》2017,62(2):61-67

Copper(II) hydroxide (as the rarely occurring mineral spertiniite) is formed under alkaline, oxidising conditions. It has been observed as a naturally occurring corrosion product of brass in sea water. But most occurrences on copper alloys are due to conservation treatments using basic solutions (sodium hydroxide or ammonia) or to intentional patination. Classical brass centrepieces (c. 1800), ‘cleaned’ with ammonia solution, developed a blue spertiniite patina in gaps, where evaporation was hindered. Additional to the danger of stress corrosion cracking this is another reason now outlawing this treatment. Copper pigment layers will transform to copper hydroxide when exposed to bases. The treatment of basic copper salts with bases has been used intentionally in the production of Bremen blue and similar pigments which can be composed of copper hydroxide as well.  相似文献   

Science classroom activities and student situational engagement     

Inkinen Janna  Klager Christopher  Schneider Barbara  Juuti Kalle  Krajcik Joseph  Lavonen Jari 《International Journal of Science Education》2019,41(3):316-329

This study examines the association between student situational engagement and classroom activities in secondary school science classrooms in Finland and the U.S. Situational engagement is conceptualised as times when students feel that a task is interesting and challenging to them and that they have the skills to complete it (see Schneider et al., 2016. Investigating optimal learning moments in U.S. and Finnish science classes. Journal of Research in Science Teaching, 53(3), 400–421. doi:10.1002/tea.21306). Data on situational engagement and classroom activities were obtained using the experience sampling method (ESM) from 247 Finnish students in 13 secondary science classrooms and 281 U.S. students in 18 secondary science classrooms. In both samples, the students tended to be situationally engaged only a small proportion of the time during their science classes. However, the Finnish students were more likely than the U.S. students to report being situationally engaged. To investigate when the students were most likely to report being situationally engaged, hierarchical logistic regression models were employed, which suggested that some classroom activities were associated with higher levels of student situational engagement than others. The Finnish students were more likely to report being situationally engaged when calculating and presenting scientific information. In the U.S., the students were more likely to report being situationally engaged while discussing scientific information and less likely when listening to the teacher. The results suggest that situational engagement is momentary and associated with specific science classroom activities.  相似文献   

Testing Measurement Invariance of Hedonic and Eudaimonic Entertainment Experiences Across Media Formats     

Carina Weinmann  Frank M. Schneider  Franziska S. Roth  Melanie J. Bindl  Peter Vorderer 《Communication methods and measures》2016,10(4):248-257

The aim of this study is to investigate the measurement invariance of media users’ entertainment experiences as conceptualized by two-process models of entertainment (i.e., enjoyment and appreciation) across different media formats. With this purpose, the present research relates to the recent rise of entertainment research, embracing more and more media types and formats with which entertainment experiences may occur. At the same time, it addresses a methodological issue that has rarely been addressed in communication research. Focusing on one of the most often used measurement instruments in entertainment research, on three different media formats (political talk shows, comedies, and dramas), the study finds evidence for configural, metric, and scalar invariance for the scale. The theoretical and practical implications of the findings are discussed.  相似文献   

Reliability,validity and fairness—key issues in assessing the quality of teaching,instructional leadership and school practice     

Guri Skedsmo  Stephan Gerhard Huber 《Educational Assessment, Evaluation and Accountability》2018,30(4):343-346

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American influencies in Brazilian physical education: clues in the specialised periodical press (1932–1950)     

Omar Schneider  Amarílio Ferreira Neto  André da Silva Mello  Wagner dos Santos  Sebastião Josué Votre 《Sport, Education and Society》2016,21(7):1053-1070

This study investigates the American presence and influences in the physical education press to understand the way in which that presence influenced and contributed to the production of a sports culture in the first half of the twentieth century. As historical sources, the study uses periodicals in the field that were published in the period 1932–1950. As a theoretical frame of reference, it uses the repertoire of the New Cultural History in terms of strategy, tactics and devices. It is written in a narrative way, following Ginzburg's style, presenting data and contextualizing them with the historic scene. Clues enabled us to infer that the American presence, which was catalysed by the Brazilian Young Men's Christian Association (YMCA), sought to shape a sports culture from physical education and society. This effort reflected the yearning of Brazilian intellectuals for modernisation and an attempt at cultural colonisation by the government of the USA.  相似文献   

Estimating High School GPA Weighting Parameters With a Graded Response Model     

John Hansen  Philip Sadler  Gerhard Sonnert 《Educational Measurement》2019,38(1):16-24

The high school grade point average (GPA) is often adjusted to account for nominal indicators of course rigor, such as “honors” or “advanced placement.” Adjusted GPAs—also known as weighted GPAs—are frequently used for computing students’ rank in class and in the college admission process. Despite the high stakes attached to GPA, weighting policies vary considerably across states and high schools. Previous methods of estimating weighting parameters have used regression models with college course performance as the dependent variable. We discuss and demonstrate the suitability of the graded response model for estimating GPA weighting parameters and evaluating traditional weighting schemes. In our sample, which was limited to self‐reported performance in high school mathematics courses, we found that commonly used policies award more than twice the bonus points necessary to create parity for standard and advanced courses.  相似文献   

Lines: Written before a Lecture on Emerson     

Gerhard Friederich 《The Educational forum》2013,77(3)

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Ancient Christmas Greetings     

Gerhard Friedrich 《The Educational forum》2013,77(2)

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