Microanalytical identification of Pb-Sb-Sn yellow pigment in historical European paintings and its differentiation from lead tin and Naples yellows   总被引：1，自引：1，他引：0  

David Hradil  Tom&#x; Grygar  Janka Hradilov  Petr Bezdi ka  Veronika Gr&#x;nwaldov  Igor Foga&#x;  Costanza Miliani 《Journal of Cultural Heritage》2007,8(4):377-386

The work is focused on identification of lead tin yellow types I and II, Naples yellow, and also on discrimination of a less common, distinct yellow pigment, the ternary Pb-Sb-Sn oxide.The knowledge about all those Pb-based yellows was in fact forgotten after introduction of modern synthetic yellows in 19th century. As late as in the last decade of the 20th century, the existence of Pb-Sb-Sn yellow and its production have been rediscovered, and only then it has been identified in colour layer of artworks.Pb-Sb-Sn yellow has recently been identified in colour layer of 17th century Italian paintings by Sandalinas and Ruiz-Moreno [C. Sandalinas, S. Ruiz-Moreno, Lead tin-antimony yellow, historical manufacture, molecular characterization and identification in seventeenth-century Italian paintings, Stud. Conserv. 49 (2003) 41–52], and here we report the finding of this pigment in Mid-European painting of the 18th and 19th centuries. Lead tin yellows, lead antimony yellow (Naples yellow), and lead antimony tin yellow were synthesized in laboratory following historical recipes, their colour was analyzed, and their structure was confirmed to provide a basis for their routine identification in microsamples of artworks by X-ray microdiffraction. Unequivocal identification of Pb-based yellows could help in authentication of traditional European paintings, because their use was temporally and also geographically specific. Combination of elemental microanalysis (X-ray fluorescence electron microanalysis) and X-ray powder microdiffraction were found very efficient in the microanalysis of colour layers of artworks with Pb-based yellows and their unequivocal identification.  相似文献   

Science and Religion Under the Microscope     

Ralph O’Connor 《Metascience》2007,16(2):261-265

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“系统动力学基础”本科课程教学思考与实践     

王文广  杨峰  朱一凡 《科教文汇》2015,(3):56-57,98

"系统动力学基础"是系统科学理论与建模仿真实践紧密结合的一门课程。本文从课堂讲授、实验教学、答疑考核角度出发,提出在课堂讲授方面需要精心准备课件,激发学员的主体意识,综合运用多种教学方法;在实验教学方面需要正确认识实验教学的作用,精心设计理论验证型实验和实际应用型实验;在答疑考核方面需要师生互动,教学相长。最后探讨了课程实施遇到的问题以及改进提高的方法。  相似文献   

Spontaneous Tumor Lysis Syndrome in an Infant: A Case Report     

Mamatha T. Shenoy  Benedicta D’Souza  Lalesh Naik Akshatha  Vivian D’Souza  Madan Gopal Rajan 《Indian journal of clinical biochemistry : IJCB》2015,30(3):360-362

Tumor lysis syndrome has been observed in patients with malignancies with high cellular burden and high cell turnover, tumor sensitive to therapy, especially after initiating medical treatment. It very rarely occurs spontaneously. The case described here is of 6 months male infant who presented with fever since 1 month and loose stools associated with blood since 15 days. The laboratory investigations showed lactate dehydrogenase (LDH) of 6,192 IU/L and serum uric acid 18.2 mg/dl along with pancytopenia. The infant presented with electrolyte abnormalities and renal failure.  相似文献   

Impact of age on haematological markers pre- and post-marathon running     

Thomas G. Martin  Rachel W. Pata  Johanna D’Addario  Lauren Yuknis  Rebecca Kingston  Richard Feinn 《Journal of sports sciences》2015,33(19):1988-1997

This study investigated whether haematological markers differ between young and masters marathon participants, running at similar performance levels. Nine young (31.89 ± 4.96 years) and eight masters (63.13 ± 4.61 years) runners participated. At five time points (pre-race through 54 h post-race), a complete blood cell count, basic metabolic panel and creatine kinase (CK) isoenzyme panel were assessed. Race performance was standardised using the World Masters Association Age Grading Performance Tables. Total CK levels were elevated for all participants at all time points post-race (P < 0.001). The CK-isoenzyme MB% was elevated across groups at 6, 30 and 54 h post-race (P < 0.01, P < 0.01 and P < 0.05), with masters runners having a higher CK-MB% at 30 and 54 h (P < 0.05, P < 0.05). Total white blood cell and neutrophil counts were elevated through 6 h post-race (P < 0.001), with higher levels found in younger runners (P < 0.001). When considering all blood work, masters runners had a higher number of abnormal values at 6, 30 and 54 h post-race (P < 0.05, P < 0.01 and P < 0.05). In conclusion, masters runners demonstrated sustained CK-MB elevation, which may suggest greater cardiac stress. However, future studies using additional cardiac markers should be completed to confirm these findings. In addition, masters runners showed an increased number of laboratory values outside normal range, indicating the body’s reduced capacity to respond to marathon running.  相似文献   

Archipelagic rhetoric: remapping the Marianas and challenging militarization from “A Stirring Place”     

Tiara R. Na’puti 《传播与批判/文化研究》2019,16(1):4-25

Engaging critical rhetorical fieldwork in the Mariana Islands archipelago, this article destabilizes colonial naming projects and US federal control that dispossess island places from Indigenous peoples. On Euro-American and military maps, archipelagoes are depicted as distant, tiny, empty, or merely (is)lands for US geostrategic control. I argue for a remapping of the Marianas as expansive, oceanic sites of resistance to colonial cartographic violence and US militarization. Fieldwork in the Marianas demonstrates how Indigenous epistemologies function as archipelagic rhetoric enacted through a Chamoru sense of place. I examine these fluid relational connections to place and their implications for decolonization.  相似文献   

Informational Sources,Social Media Use,and Race in the Flint,Michigan, Water Crisis     

Ashleigh M. Day  Sydney O’Shay-Wallace  Matthew W. Seeger  Shawn P. McElmurry 《Communication Studies》2019,70(3):352-376

Safe, clean water is necessary for health and well-being. Water issues affect minority and vulnerable populations at disproportionate rates, including the poor and racial and ethnic minorities. An investigation of the relationships of race, social media use, and informational sources during the municipal water crisis in Flint, Michigan, reflects an instrumental view of communication and uses and gratifications theory in this study. Data from 208 Flint residents in 2016 indicated that African American respondents favored interpersonal networks and resources and were more likely than other racial groups to obtain current information about the water crisis via Instagram. Preferred channels and sources to receive additional crisis information varied on the basis of race.  相似文献   

Framing Refuge: Media,Framing, and Sanctuary Cities     

Benjamin Gonzalez O’Brien  Elizabeth Hurst  Loren Collingwood 《Mass Communication and Society》2019,22(6):756-778

The refugee sanctuary movement in the United States has shifted to include undocumented immigrants fleeing violence and economic strife. Given the negative tenor of coverage of undocumented immigration, and ties between framing and policy views on immigration, how the media frames sanctuary cities is likely to impact public perceptions of these cities and their policies. To assess media coverage of sanctuary policies, we analyzed articles from five national newspapers from 1980 to 2017 with both human content analysis and dictionary-based computational analysis. We find that framing around religion/morality and conflict has decreased, while stories focusing on crime and partisanship have increased. We discuss implications for public opinion and the likelihood that the American public will take their cues from media framing and elite discourse when it comes to sanctuary policies.  相似文献   

父母外出务工与留守子女辍学——基于CHNS调查数据的经验分析     

苏群  徐月娥  陈杰 《教育与经济》2015,(2):67-72

利用中国健康与营养调查(CHNS)数据,本研究对农村父母外出务工与留守子女初、高中阶段辍学行为之间的关系进行了实证分析。结果表明:父亲外出务工会显著降低留守子女初、高中阶段的辍学概率,母亲外出务工则会显著增加留守子女初中阶段的辍学概率。此外,免费义务教育政策的实施在较大程度上降低了留守子女的初、高中阶段的辍学概率;与那些父母受教育程度较低的留守子女相比,父母受教育程度越高的留守子女越不容易辍学;家庭子女数和机会成本会提高留守子女初中阶段辍学的概率。因此,为降低农村中学阶段子女辍学率,政府应当增加农村妇女当地就业机会以减少母亲外出的影响、推进户籍制度改革使随迁子女能获得同等的教育机会,并为高中阶段和多子女家庭提供教育补贴。  相似文献   

体育学院优秀散打运动队管理现状研究     

刘健  刘云安  高露露 《山东教育学院学报》2015,(2):104-108

本文采用文献资料法、问卷调查法、访谈法、数理统计法对我国体育院校优秀散打运动队的基本情况和运动员在思想、学习、训练以及生活管理中的现状进行分析探讨,希望能及时解决管理中存在的问题,从而为进一步提高我国散打运动队的管理提供服务。  相似文献