Characterization of microstructure and mechanical properties of polycrystalline precipitation hardened Co-base superalloys with a focus on deformation mechanisms

Im Rahmen dieser Arbeit wurde eine Serie von anwendungsnahen, γ′ gehärteten Co-Basis Schmiedelegierungen entwickelt und harakterisiert. Optimierte Wärmebehandlungen führten für alle Legierungen zur Ausbildung einer γ/γ′-Mikrostruktur, welche bi- oder tridisperse γ′-Teilchenverteilungen aufwies und einen möglichst hohen Härtungsbeitrag lieferte. Durch das Einbringen von orngrenzenpinnenden intermetallischen Phasen konnte die Korngröße auch bei hohen Anwendungstemperaturen stabil gehalten werden. Die Druckfestigkeit der Legierungen lag auf vergleichbarem Niveau wie die von Ni-basierten Schmiedelegierungen. Insbesondere bei Temperaturen über 750 °C sind die Co-Basis Schmiedelegierungen stabiler hinsichtlich ihrer mechanischen Eigenschaften und weisen in Relation höhere Festigkeiten auf. Besonders gute mechanische Stabilität zeigten die untersuchten Legierungen unter Kriechbelastung, wo teilweise um zwei Größenordnungen niedrigere Kriechraten erzielt wurden als für vergleichbare etablierte Ni-Basis Schmiedelegierungen. Untersuchungen der vorliegenden Verformungsmechanismen zeigten, dass in den Co-Basis Schmiedelegierungen Mikroverzwillingung der dominante Verformungsmechanismus ist. Mit Hilfe von hochauflösender Transmissionselektronenmikroskopie konnte nachgewiesen werden, dass das Wachstum der Zwillinge durch das Gleiten von einzelnen Shockley-Partialversetzungen erfolgt, was durch Segregationsprozesse an der Zwillingsgrenze unterstützt wird. Durch eine umfassende Analyse verschiedener mikrostruktureller Parameter wie der Korngröße, der γ′-Teilchengrößenverteilung und des γ′–Volumenanteils und der Gitterfehlpassung sowie der elementaren Zusammensetzung von γ- und γ′-Phasen konnten die Festigkeitsbeiträge in den Legierungen abgeschätzt werden.A series of application-oriented γ′ hardened Co-base cast-and-wrought superalloys was developed and analyzed in the course of this thesis. Optimized heat treatments led to the development of bi- or tridispersive γ/γ′ particle distributions in all alloys that result in high strength. The introduction of intermetallic phases at the grain boundaries stabilized the grain structure up to high application temperatures. The compression strength of the alloys was comparable to commercially available cast-and-wrought alloys. At temperatures above 750 °C, the Co-base superalloys proved to be even more stable than their Ni-base counterparts and provided even higher strength. In addition, the Co-base alloys exhibited excellent creep properties with minimum creep rates reduced by up to two orders of magnitude compared to Ni-base cast-and-wrought alloys. Investigations of the creep mechanisms revealed microtwinning as the dominating deformation mechanism prevailing in the Co-base alloys. High-resolution transmission electron microscopy could be used to identify single Shockley partial dislocations that lead to twin growth by segregation assisted slip along the twin boundary. A comprehensive analysis of several microstructural parameters like grain size, γ′ particle distribution and volume fraction and lattice mismatch as well as a chemical analysis of the composition of γ and γ′ phase allowed to evaluate the different hardening contributions in the alloys

γ/γ\u27 Co-base superalloys – new high temperature materials beyond Ni-base Superalloys?

In 2006 a new L12 phase, Co3(Al,W), was discovered in the Co-Al-W system which has led to the development of novel Co-base superalloys with g/g¢ microstructures similar to those of the well-established Ni-base superalloys. First investigations on simple ternary alloys could show that these Co-Al-W based alloys exhibit higher solidus temperatures and show less segregations after casting compared to typical Ni-base superalloys. This leads to the question whether this g/g¢ Co-base superalloys can be regarded as new class of high temperature materials that can compete with or even supersede established Ni-base superalloys. In the first part of the talk it will be shown how alloy properties change, when the base element Ni is gradually substituted by Co in a series of Ni-Co-Al-W-Cr alloys with otherwise constant element contents of Al, W and Cr. All alloys form g/g¢ microstructure after a standard aging treatment with a similar g¢ volume content. Liquidus and solidus temperatures are hardly influenced by the Ni/Co content, but the g¢ solvus temperature is strongly decreasing with increasing Co content. This indicates that the potential application temperature of g/g¢ Co-base superalloys will not be beyond the maximum application temperature of advanced single crystal Ni-base superalloys. However, this also shows that g/g¢ Co-base superalloys have a great potential as wrought alloys since the solvus temperature of the intermetallic compound is comparatively low, which gives a large processing window, and because a high volume fraction of the L12 phase at temperatures up to 900°C can be achieved. Please click Additional Files below to see the full abstract

Digital Agency

In diesem Artikel wird das Konzept der Digital Agency (en) / digitaler Handlungsmacht (de) vorgestellt. Digital Agency (DA) behandelt neben Wissen und Fertigkeiten auch die Dimensionen Selbstvertrauen und Verantwortlichkeit im Umgang mit digitalen Artefakten. Digitale Handlungsmacht wird als die Fähigkeit beschrieben, digitale Kontexte zu kontrollieren und sich ihnen anzupassen. Der Artikel würdigt die Erweiterung des Konzepts von digitalen Kompetenzen und stellt gleichzeitig zwei zentrale Lücken zur Diskussion. Erstens zeigen wir, dass die grundlagentheoretische Fundierung und Verortung des Konzepts noch nicht hinreichend ausgeführt und begründet ist. Zweitens wird klar, dass feministische und intersektionale Dimensionen im DA-Konzept bislang keine Beachtung finden. Auf Basis dieser kritischen Würdigung stellen wir abschließend mögliche theoretische Anknüpfungspunkte und weitere Forschungs- und Entwicklungsfragen vor

Fcγ Receptor IIB Controls Skin Inflammation in an Active Model of Epidermolysis Bullosa Acquisita

Epidermolysis bullosa acquisita (EBA) is an autoimmune skin blistering disease characterized by IgG autoantibodies (aAb) against type VII collagen (COL7). The mechanisms controlling the formation of such aAbs and their effector functions in the skin tissue are incompletely understood. Here, we assessed whether the inhibitory IgG Fc receptor, FcγRIIB, controls the development of autoimmune skin blistering disease in an active model of EBA. For this purpose, we immunized congenic EBA-susceptible B6.SJL-H2s (B6.s) and B6.s-Fcgr2b−/− mice with the immunodominant vWFA2 region of COL7. B6.s-Fcgr2b−/− mice developed a strong clinical phenotype with 15 ± 3.3% of affected body surface area at week 4. In contrast, the body surface area in B6.s mice was affected to a maximum of 5% at week 6 with almost no disease signs at week 4. Surprisingly, we already found strong but similar COL7-specific serum IgG1 and IgG2b aAb production at week 2. Further, aAb and C3b deposition in the skin of B6.s and B6.s-Fcgr2b−/− mice increased between weeks 2 and 6 after vWFA2 immunization. Importantly, neutrophil skin infiltration and activation was much stronger in B6s-Fcgr2b−/− than in B6.s mice and already present at week 2. Also, the early aAb response in B6.s-Fcgr2b−/− mice was more diverse than in wt B6.s mice. Reactive oxygen species (ROS) release from infiltrating neutrophils play a crucial role as mediator of skin inflammation in EBA. In line, sera from B6.s and B6.s-Fcgr2b−/− mice induced strong ROS release from bone marrow-neutrophils in vitro. In contrast to the antibody-transfer-induced EBA model, individual targeting of FcγRIII or FcγRIV decreased ROS release to 50%. Combined FcγR blocking abrogated ROS release from BM neutrophils. Also, ROS release induced by COL7-specific serum IgG aAbs was significantly higher using BM neutrophils from B6.s-Fcgr2b−/− than from B6.s mice. Together, our findings identified FcγRIIB as a suppressor of skin inflammation in the active EBA model through inhibition of early epitope spreading, protection from strong early neutrophil infiltration to and activation of neutrophils in the skin and suppression of FcγRIII activation by IgG1 aAbs which drive strong ROS release from neutrophils leading to tissue destruction at the dermal-epidermal junction

Cabibbo Haze in Lepton Mixing

Quark-lepton unification suggests Cabibbo-sized effects in lepton mixings, which we call Cabibbo haze. We give simple examples and explore possible Wolfenstein-like parametrizations of the MNSP matrix which incorporate leptonic Cabibbo shifts. We find that the size of the CHOOZ angle is not always correlated with the observability of CP violation.Comment: 10 page

Correlates of Coronavirus Disease 2019 Inpatient Mortality at a Southern California Community Hospital With a Predominantly Hispanic/Latino Adult Population

© The Author(s) 2023. Published by Oxford University Press on behalf of Infectious Diseases Society of America. Financial support. None.BACKGROUND: Studies of inpatient coronavirus disease 2019 (COVID-19) mortality risk factors have mainly used data from academic medical centers or large multihospital databases and have not examined populations with large proportions of Hispanic/Latino patients. In a retrospective cohort study of 4881 consecutive adult COVID-19 hospitalizations at a single community hospital in Los Angeles County with a majority Hispanic/Latino population, we evaluated factors associated with mortality. METHODS: Data on demographic characteristics, comorbidities, laboratory and clinical results, and COVID-19 therapeutics were abstracted from the electronic medical record. Cox proportional hazards regression modeled statistically significant, independently associated predictors of hospital mortality. RESULTS: Age ≥65 years (hazard ratio [HR] = 2.66; 95% confidence interval [CI] = 1.90-3.72), male sex (HR = 1.31; 95% CI = 1.07-1.60), renal disease (HR = 1.52; 95% CI = 1.18-1.95), cardiovascular disease (HR = 1.45; 95% CI = 1.18-1.78), neurological disease (HR = 1.84; 95% CI = 1.41-2.39), D-dimer ≥500 ng/mL (HR = 2.07; 95% CI = 1.43-3.0), and pulse oxygen level <88% (HR = 1.39; 95% CI = 1.13-1.71) were independently associated with increased mortality. Patient household with (1) multiple COVID-19 cases and (2) Asian, Black, or Hispanic compared with White non-Hispanic race/ethnicity were associated with reduced mortality. In hypoxic COVID-19 inpatients, remdesivir, tocilizumab, and convalescent plasma were associated with reduced mortality, and corticosteroid use was associated with increased mortality. CONCLUSIONS: We corroborate several previously identified mortality risk factors and find evidence that the combination of factors associated with mortality differ between populations.Peer reviewe

A randomised controlled trial of an intervention to increase the implementation of a healthy canteen policy in Australian primary schools: study protocol

Background: The implementation of healthy school canteen policies has been recommended as a strategy to help prevent unhealthy eating and excessive weight gain. Internationally, research suggests that schools often fail to implement practices consistent with healthy school canteen policies. Without a population wide implementation, the potential benefits of these policies will not be realised. The aim of this trial is to assess the effectiveness of an implementation intervention in increasing school canteen practices consistent with a healthy canteen policy of the New South Wales (NSW), Australia, government known as the \u27Fresh Tastes @ School NSW Healthy School Canteen Strategy\u27.Methods/design: The parallel randomised trial will be conducted in 70 primary schools located in the Hunter region of New South Wales, Australia. Schools will be eligible to participate if they are not currently meeting key components of the healthy canteen policy. Schools will be randomly allocated after baseline data collection in a 1:1 ratio to either an intervention or control group using a computerised random number function in Microsoft Excel. Thirty-five schools will be selected to receive a multi-component intervention including implementation support from research staff, staff training, resources, recognition and incentives, consensus and leadership strategies, follow-up support and implementation feedback. The 35 schools allocated to the control group will not receive any intervention support as part of the research trial. The primary outcome measures will be i) the proportion of schools with a canteen menu that does not contain foods or beverages restricted from regular sale (\u27red\u27 and \u27banned\u27 items) and ii) the proportion of schools where healthy canteen items (\u27green\u27 items) represent the majority (&gt;50%) of products listed on the menu. Outcome data will be collected via a comprehensive menu audit, conducted by dietitians blind to group allocation. Intervention effectiveness will be assessed using logistic regression models adjusting for baseline values.Discussion: The proposed trial will represent a novel contribution to the literature, being the first randomised trial internationally to examine the effectiveness of an intervention to facilitate implementation of a healthy canteen policy

Author Correction: A consensus-based transparency checklist.

An amendment to this paper has been published and can be accessed via a link at the top of the paper

Nous:

Im Rahmen eines Seminars der Fakultät für Philosophie I an der Ruhr-Universität Bochum setzten sich Studierende im Sommersemester 2017 mit populärwissenschaftlichen Einführungen in die Philosophie auseinander - ein Jahr später nahmen sie selbst die Feder in die Hand. In dem Seminar „Philosophisches Schreiben“ trafen sich im Sommersemester 2018 wöchentlich bis zu 45 Nachwuchsphilosoph:innen, die den Raum bekamen, ihre eigenen philosophischen Texte einander vorzustellen. Nach dem Vorbild der Gruppe 47 wurden die Beiträge kritisch reflektiert und diskutiert, um adressatengerechte und kreative Geschichten, Gedichte oder Essays zu entwickeln, die Lust auf mehr Philosophie machen. In dieser Anthologie mit dem Namen „Nous. Philosophische Texte zum Schmunzeln und Staunen“ finden sich ausgewählte Beiträge wieder, die in den verschiedensten literarischen Formen philosophische Phänomene und Theorien aufbereiten. Philosophie wird somit nicht nur unterhaltsam und lebensnah vermittelt, sondern ist auch ohne Vorwissen leicht zugänglich und verständlich. Das Ziel dieses Werks ist es, die Philosophie in ihren verschiedensten Facetten aus dem sprichwörtlichen „Elfenbeinturm“ der Universität heraus, in das alltägliche Leben von Jedermann zu bringen. So richten sich die Beiträge an Philosophieinteressierte und -begeisterte, die neugierig auf die bunte Welt der Philosophie sind. Die Herausgeber:innen Natalie Berg (geboren 1990 in Leipzig) studierte Philosophie und Religionswissenschaft im 2-Fach-Master an der Ruhr-Universität Bochum. Sie gehört zum Team der Arbeitsstelle „Kulturwissenschaftliche Grundlagen“ der Fakultät für Kultur- und Sozialwissenschaften an der FernUniversität in Hagen, wo sie Studierende bei ihren wissenschaftlichen Schreib- und Arbeitsprozessen begleitet. Ferner arbeitet sie an ihrer Promotion im Bereich Religionsphilosophie. Lisa Freund (geboren 1991 in Herne) studierte Philosophie und Geschichte auf Lehramt und ist nach Beendigung des Vorbereitungsdienstes als Lehrerin an einer Bochumer Schule tätig. Die Liebe zur Philosophie entwickelte sich vor gut 20 Jahren durch Jostein Gaarders Werk „Sofies Welt“. Eine solche Begeisterung möchte sie nicht nur bei ihren Schüler:innen, sondern auch bei den Lesenden des Buches wecken. Hans-Ulrich Lessing (geboren 1953 in Dortmund) promovierte 1981 in Bochum, wo er 1995 auch habilitierte. Er war seit 2001 apl. Professor für Philosophie an der Ruhr-Universität Bochum. Als Mitarbeiter der&nbsp;Dilthey-Forschungsstelle ist er unter anderem Mitherausgeber von Diltheys Gesammelten Schriften. Die Autor:innen Die Texte stammen von (ehemaligen) Bachelor- und Masterstudierenden der Philosophie an der Ruhr-Universität Bochum, die durch ihre Werke ihre Leidenschaft zum Fach ausdrücken