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Influence of test procedure on dielectric breakdown strength of alumina

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Journal of Advanced Ceramics 2019年第2期8卷 247-255页

作者： bjoern MIELLER Bundesanstalt fuer Materialforschung und-pruefung (BAM) Division Advanced Technical Ceramics

Dielectric strength testing of ceramics can be performed with various setups and parameters. Comparisons of results from different sources are often not meaningful, because the results are strongly dependent on the actual testing procedure. The aim of this study is to quantify the influence of voltage ramp rate, electrode size, electrode conditioning, and sample thickness on the measured AC dielectric strength of a commercial alumina. Mean values, Weibull moduli, and failure probabilities determined in standardized short time tests are evaluated and related to withstand voltage tests. Dielectric strength values in the range from 21.6 to 33.2 kV·mm–1 were obtained for the same material using different testing procedures. Short time tests resulted in small standard deviations(< 2 kV·mm–1) and high Weibull moduli around 30, while withstand tests at voltage levels with low and virtual zero failure probability in short time tests resulted in large scatter of withstand time and Weibull moduli < 1. The strong decrease in Weibull moduli is attributed to progressive damage from partial discharge and depolarization during AC testing. These findings emphasize the necessity of a thorough documentation of testing procedure and highlight the importance of withstand voltage tests for a comprehensive material characterization.

关键词： dielectric strength dielectric breakdown withstand voltage test high AC voltage testing

Fight them or feed them:how the intestinal mucus layer manages the gut microbiota

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Gastroenterology Report 2019年第1期7卷 3-12,I0001页

作者： bjoern O.Schroeder Wallenberg Laboratory and Sahlgrenska Center for Cardiovascular and Metabolic Research Department of Molecular and Clinical MedicineInstitute of MedicineBruna Stra°ket 16University of GothenburgSE 41345 GothenburgSweden

The intestinal tract is inhabited by a tremendous number of microorganisms,termed the gut *** microorganisms live in a mutualistic relationship with their host and assist in the degradation of complex *** the gut microbiota is generally considered beneficial,the vast number of microbial cells also form a permanent threat to the ***,the intestinal epithelium is covered with a dense layer of mucus to prevent translocation of the gut microbiota into underlying *** mucus is an organized glycoprotein network with a host-specific glycan *** the mucus layer has long been considered a passive,host-designed barrier,recent studies showed that maturation and function of the mucus layer are strongly influenced by the gut *** return,the glycan repertoire of mucins can select for distinct mucosa-associated bacteria that are able to bind or degrade specific mucin glycans as a nutrient *** the intestinal mucus layer is at the crucial interface between host and microbes,its breakdown leads to gut bacterial encroachment that can eventually cause inflammation and ***,a dysfunctional mucus layer has been observed in colitis in mice and ***,the increased consumption of a low-fiber Western-style diet in our modern society has recently been demonstrated to cause bacteria-mediated defects of the intestinal mucus ***,I will review current knowledge on the interaction between gut bacteria and the intestinal mucus layer in health and *** the molecular details of this host–microbe interaction may contribute to the development of novel treatment options for diseases involving a dysfunctional mucus layer,such as ulcerative colitis.

关键词： Dietary fiber gut microbiota host-microbe interaction inflammatory bowel disease mucus mucin mucosal barrier metabolic disease probiotics ulcerative colitis

Outlook on the gut microbiota

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Gastroenterology Report 2022年第1期10卷 1-2页

作者： bjoern O.Schroeder Department of Molecular Biology UmeaUniversityUmeaSweden Laboratory for Molecular Infection Medicine Sweden(MIMS) UmeaUniversityUmeaSweden

Despite being a rather young research field that only emerged in the last two decades,it has become clear that the gut microbiota is an essential part of our body that strongly influences the processes that regulate our health and *** this Special Issue of Gastroenterology Report,we have compiled a collection of articles which discuss that microbial signals deriving from our internal bioreactor are by no means restricted to the gut environment,and why it is thus reasonable to consider the gut microbial community as an additional organ to our body.

关键词： Outlook spite restricted

Morphological residual convolutional neural network(M-RCNN)for intelligent recognition of wear particles from artificial joints

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Friction 2022年第4期10卷 560-572页

作者： Xiaobin HU Jian SONG Zhenhua LIAO Yuhong LIU Jian GAO bjoern MENZE Weiqiang LIU Department of Computer Science Technical University of MunichGarching 85748Germany School of Biomedical Engineering Sun Yat-sen UniversityGuangzhou 510006China Key Laboratory of Biomedical Materials and Implant Devices Research Institute of Tsinghua University in ShenzhenShenzhen 518057China State Key Laboratory of Tribology Tsinghua UniversityBeijing 100084China Mckelvey School of Engineering Washington University in Saint LouisSt.LouisMO 63130USA

Finding the correct category of wear particles is important to understand the tribological ***,manual identification is tedious and *** here propose an automatic morphological residual convolutional neural network(M-RCNN),exploiting the residual knowledge and morphological priors between various particle *** also employ data augmentation to prevent performance deterioration caused by the extremely imbalanced problem of class *** results indicate that our morphological priors are distinguishable and beneficial to largely boosting overall performance.M-RCNN demonstrates a much higher accuracy(0.940)than the deep residual network(0.845)and support vector machine(0.821).This work provides an effective solution for automatically identifying wear particles and can be a powerful tool to further analyze the failure mechanisms of artificial joints.

关键词： wear particles classifier morphological priors data augmentation deep residual network

Public Perceptions and Support of Renewable Energy in North America in the Context of Global Climate Change

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International Journal of Disaster Risk Science 2015年第4期6卷 385-398页

作者： bjoern Hagen David Pijawka School of Geographical Sciences and Urban Planning Arizona State University

There is substantial interest in developing a coherent and effective North American renewable energy policy as a way to secure energy but also to mitigate global climate change. Based on surveys of the public in Canada,Mexico, and the United States, the article shows the levels of concern over climate change threats, perceived risk,knowledge of climate change policies, levels of uncertainty, and other perception factors to help understand the relationships between public perceptions and policy preferences for renewable energy. Results show national differences between the three countries in nearly all climate change perceptions, with Mexico reflecting the highest levels of concern and the United States the lowest. Mexico also shows the greatest support for renewable energy sources. However, the results show very high levels of uncertainty about climate change dimensions concerning risk, science, and knowledge and the effectiveness of policy approaches. The data demonstrate strong statistical correlations between risk perception factors and preferences for mitigation policies in the form of renewable energy policies.

关键词： Climate change Cross-national comparison Environmental policy North America Public perceptions Renewable energy

A self-made, low-cost infrared system for evaluating the sciatic functional index in mice

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Neural Regeneration Research 2016年第5期11卷 829-834页

作者： Lukas Fricker Vincenzo Penna Florian Lampert G.bjoern Stark Christian Witzel Georgios Koulaxouzidis Department of Plastic and Hand Surgery University of Freiburg Medical Center Plastic and Reconstructive Surgery Charité – Universit?tsmedizin Berlin

The sciatic functional index（SFI） is a popular parameter for peripheral nerve evaluation that relies on footprints obtained with ink and paper. Drawbacks include smearing artefacts and a lack of dynamic information during measurement. Modern applications use digitized systems that can deliver results with less analytical effort and fewer mice. However, the systems are expensive（€40,000）. This study aimed to evaluate the applicability and precision of a self-made, low-cost infrared system for evaluating SFI in mice. Mice were subjected to unilateral sciatic nerve crush injury（crush group; n = 7） and sham operation（sham group; n = 4）. They were evaluated on the day before surgery, the 2nd, 4th and 6th days after injury, and then every day up to the 23rd day after injury. We compared two SFI evaluation methods, i.e., conventional inkand-paper SFI（C-SFI） and our infrared system（I-SFI）. Our apparatus visualized footprints with totally internally reflected infrared light（950 nm） and a camera that can only detect this wavelength. Additionally we performed an analysis with the ladder beam walking test（LBWT） as a reference test. I-SFI assessment reduced the standard deviation by about 33 percent, from 11.6 to 7.8, and cut the variance around the baseline to 21 percent. The system thus requires fewer measurement repetitions and fewer animals, and cuts the cost of keeping the animals. The apparatus cost €321 to build. Our results show that the process of obtaining the SFI can be made more precise via digitization with a self-made, low-cost infrared system.

关键词： nerve regeneration sciatic nerve crush frustrated total internal reflection infrared ladder beamwalking test error rate mouse peripheral nerve injury neural regeneration

Surface modification of biomedical Mg-Ca and Mg-Zn-Ca alloys using selective laser melting: Corrosion behaviour, microhardness and biocompatibility

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Journal of Magnesium and Alloys 2021年第6期9卷 2155-2168页

作者： Xiyu Yao Jincheng Tang Yinghao Zhou Andrej Atrens Matthew S.Dargusch bjoern Wiese Thomas Ebel Ming Yan School of Materials Science and Engineering Harbin Institute of TechnologyHarbin 150001China Department of Materials Science and Engineering Southern University of Science and TechnologyShenzhen 518055China The University of Queensland School of Mechanical and Mining EngineeringCentre for Advanced Materials Processing and Manufacturing(AMPAM)QLD 4072 Australia Institute of Materials Research Helmholtz-Zentrum GeesthachtGeesthacht 21502Germany

Magnesium alloys such as Mg–Ca and Mg–Zn–Ca are good orthopaedic materials;however their tendency to corrode is *** we utilize selective laser melting(SLM)to modify the surface of these Mg alloys to simultaneously improve the corrosion behaviour and *** corrosion rate decreased from 2.1±0.2 mm/y to 1.0±0.1 mm/y for the laser-processed Mg–0.6Ca,and from 1.6±0.1 mm/y to 0.7±0.2 mm/y for laser-processed Mg–0.5Zn–*** microhardness increased from 46±1 HV to 56±1 HV for Mg–0.6Ca,and from 47±3 HV to 55±3 HV for Mg–0.5Zn–*** addition,good biocompatibility remained in the laser processed Mg *** improved properties are attributed to laser-induced grain refinement,confined impurity elements,residual stress,and modified surface *** results demonstrated the potential of SLM as a surface engineering approach for developing advanced biomedical Mg alloys.

关键词： Mg alloys Selective laser melting Surface modification Corrosion behaviour Microhardness

History of Geology in Norden

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Episodes 2008年第1期31卷 185-192页

作者： bjoern Sundquist Ilmari Haapala Jens Morten Hansen Geir Hestmark Sigurdur Steinthorsson Department of Earth Sciences Uppsala University Villavaegen 16 SE-75236 Uppsala Sweden. Department of Geology University of Helsinki P.O.Box 64 FI-00014 Helsinki Finland. Geological Survey of Denmark and Greenland （GEUS） Фster Voldgade 10 DK-1350 KCbenhavn K Denmark. Institute of Biology University of Oslo P.O.Box 1066 Blindern NO-0316 Oslo Norway. Department of Earth Sciences University of Iceland Jardarhaga 2-6 IS-107 Reykjavfk Iceland.

The Nordic countries of Denmark, Finland, Iceland, Norway, and Sweden have been closely connected for many centuries, not least from a geological point of view. Scientific cooperation as well as contentions have been common. The earliest known records of ＂geological＂ treatises are from the 16th century, but especially in the 18th century, when the natural sciences flourished all over Europe, Nordic scholars were in the forefront in geochemistry, mineralogy, and paleontology. This was also the century when ＂geology＂ started to be taught at the universities, and science academies were founded in Norden, adding greatly to ＂geological＂ studies. In the 19th century, like in so many other countries, national geological survey organizations and geological societies were founded. In Norden, geological research has long traditions within mineralogy and ore geology, paleontology and stratigraphy, tectonics and structural geology. During the last century, focus has turned also to Quaternary and glacial geology, igneous and metamorphic petrology, geochemistry, micropaleontology, petroleum geology, sedimentology, marine geology, geophysics, geochronology, and research related to geothermal energy and deposition of radioactive waste products. In many of these research areas, Nordic geoscientists have contributed greatly over the years to the development of the science of geology.

关键词：地质学北欧国家地球化学矿物学

Environmental Geology

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Episodes 2008年第1期31卷 155-162页

作者： Reijo Salminen Anne Kousa Rolf Tore Ottesen Olle Selinus Eiliv Steinnes Timo Tarvainen bjoern OEhlander Geological Survey of Finland P.O. Box 96 FIN-02151 Espoo Finland. Geological Survey of Norway N-7491 Trondheim Norway. Geological Survey of Sweden P.O. Box 670 S-75128 Uppsala Sweden. Institutt for Kjemi Norges teknisk-naturvitenskapelige universitet N-7491 Trondheim Norway. Lulea University of Technology SE-97187 Lulea.

The mining environment, medical geology and urban geochemistry form a group of related scientific disciplines that have developed strongly during recent years in the Nordic countries. Modern legislation controls the environmental issues. Close co-operation of researchers and legislators has improved the quality and safety of life in the societies of the Nordic countries. In mining environmental studies, methods that are suitable in Arctic conditions have been developed; in medical geology, the input from the Nordic countries has made it an appreciated scientific discipline throughout the world, and in the case of the urban environment, methods developed by our geochemists have especially improved the health conditions, particularly of children.

关键词：环境地质学医学地质学环境利用城市地球化学