Andreas Krell

Universidade Federal de Alagoas

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Co-Authors

Gerhard Dieckmann

Alfred-Wegener-Institut Helmholtz-Zentrum für Polar- und Meeresforschung

Klaus-Ulrich Valentin

Alfred-Wegener-Institut Helmholtz-Zentrum für Polar- und Meeresforschung

David N. Thomas

University of Helsinki

Thomas Möck

University of East Anglia

Paul S. Blank

Eunice Kennedy Shriver National Institute of Child Health and Human Development

Jens Klimke

RWTH Aachen University

Christiane Uhlig

Leibniz Institute for Research on Society and Space

Thomas Hutzler

Fraunhofer Institute for Ceramic Technologies and Systems

Adrian Goldstein

Technion – Israel Institute of Technology

Z. Burshtein

Ben-Gurion University of the Negev

Cooperative Institutions

Nagoya University of Commerce and Business

Alfred-Wegener-Institut Helmholtz-Zentrum für Polar- und Meeresforschung

Fraunhofer Institute for Ceramic Technologies and Systems

Fraunhofer Society

National Institute of Advanced Industrial Science and Technology

Leibniz Institute for Solid State and Materials Research

American Ceramic Society

Hokkaido University

Nagoya University

University of Bremen

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Ceramics Based on Alumina: Increasing the Hardness for Tool Applications

Andreas Krell

Cutting tool

10.1002/9783527618217.ch19

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Citations (3)

MiR‐16‐5p is frequently down‐regulated in astrocytic gliomas and modulates glioma cell proliferation, apoptosis and response to cytotoxic therapy

Neuropathology and Applied Neurobiology (2018)

Andreas Krell Marietta Wolter Nina Stojcheva Caroline Hertler Franziska Liesenberg

Aberrant expression of microRNAs (miRNAs) is frequent in various cancers including gliomas. We aimed to characterize the role of miR-16-5p as a candidate tumour suppressor miRNA in gliomas.Real-time PCR-based approaches were used for miRNA and mRNA expression profiling of glioma and non-neoplastic brain tissues as well as glioma cell lines. Protein levels were determined by Western blotting. In vitro analyses were performed following overexpression of miR-16-5p, trichostatin A (TSA) treatment, and siRNA-mediated knock-down of HDAC3 in glioma cells. Effects of miR-16-5p on glioma cell viability, apoptosis and response to irradiation and temozolomide (TMZ) were assessed.Expression of miR-16-5p was reduced relative to control brain tissue in isocitrate dehydrogenase (IDH)-mutant astrocytomas of World Health Organization (WHO) grades II, III and IV, and a subset of IDH-wildtype glioblastomas WHO grade IV. MiR-16-5p expression was lower in IDH-mutant than in IDH-wildtype gliomas, and down-regulated in IDH-wildtype glioma lines. MiR-16-5p overexpression reduced expression of important cell cycle and apoptosis regulators in glioma cells, including CDK6, CDC25A, CCND3, CCNE1, WEE1, CHEK1, BCL2 and MCL1. In line, CDK6, WEE1, CHEK1, BCL2 and MCL1 transcript levels were increased in WHO grade III or IV gliomas. TSA treatment and HDAC3 knockdown in glioma cells induced miR-16-5p up-regulation and reduced expression of its targets. Moreover, miR-16-5p overexpression inhibited proliferation and induced apoptosis in various glioma cell lines and increased sensitivity of A172 glioma cells to irradiation and TMZ.Reduced expression of miR-16-5p contributes to glioma cell proliferation, survival and resistance to cytotoxic therapy.

Cyclin-dependent kinase 6

Temozolomide

Trichostatin A

MCL1

10.1111/nan.12532

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Citations (46)

THE ENVIRONMENTAL FUNCTION OF FOREST PROPERTY

Veredas do Direito Direito Ambiental e Desenvolvimento Sustentável (2023)

Andreas Krell

The article analyzes the effects of the environmental function of forest property in Brazil, based on recent decisions by the Superior Court of Justice on the delimitation of property content and the appropriateness of compensation referring to restrictions on the use of protected forest areas. The aim is to demonstrate that there was a significant redefinition of the dogmatic institute of indirect expropriation and a strong conditioning of the owners’ right to compensation. The jurisprudential and doctrinal bases of the social and environmental function of real estate in Germany are also discussed, in the context of forest protection and conservation, in order to compare the feasibility and coherence of the solutions adopted in the two countries. The research makes use of bibliographical and documentary survey, based on theoretical models, normative provisions and court-judged cases. It is concluded that the national legal system of forest protection has already advanced a lot, but it still needs to improve its instrumental framework, including on the basis of other legal systems’ experiences.

Expropriation

10.18623/rvd.v20.2519-ing

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Die normative Ausgestaltung des brasilianischen Umweltrechtes und die Hauptprobleme seiner methodisch abgesicherten Anwendung

Jahrbuch des öffentlichen Rechts der Gegenwart Neue Folge (2014)

Andreas Krell

10.1628/joer-2014-0032

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Citations (1)

Journal of the European Ceramic Society (2008)

Andreas Krell

10.1016/j.jeurceramsoc.2008.03.021

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Physics and Technology of Transparent Ceramic Armor: Sintered Al2O3 vs Cubic Materials

Andreas Krell Thomas Hutzler Jens Klimke

Abstract : Sintered sub-micrometer alumina (alpha-Al2O3) is the hardest transparent armor. However, its trigonal structure gives rise to a strong thickness effect that makes thicker components translucent. Cubic ceramics (no birefringence!), on the other hand, are less hard but may exhibit an improved transmission. Known cubic armor ceramics are manufactured in a way resulting in coarse microstructures with low hardness. Therefore, a cubic sub-micrometer spinel was developed here that associates a high hardness > 14 GPa with an in-line transmission approaching the theoretical limit - with the consequence that the thickness effect becomes very small, and transparent components can be manufactured with several mm thickness without loss of transmissivity. Additionally, weight benefits at high protective strength are expected because the hard components can be designed thinner than using known spinel or AlON grades.

Armour

Micrometer

Cubic crystal system

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Citations (5)

REGULATION OF PROLINE METABOLISM UNDER SALT STRESS IN THE PSYCHROPHILIC DIATOM FRAGILARIOPSIS CYLINDRUS (BACILLARIOPHYCEAE)¹

Journal of Phycology (2007)

Andreas Krell Dietmar Funck Ina Plettner Uwe John Gerhard Dieckmann

Fragilariopsis cylindrus (Grunow) Willi Krieger, a bipolar psychrophilic and highly abundant diatom, experiences strong shifts in salinity during the formation of sea ice. We investigated the effects of osmotic stress due to an increased salt concentration from 34 to 70 practical salinity units (PSU) in conjunction with a temperature decrease from 0°C to −4°C on the anabolic and catabolic pathways of proline metabolism. Gene expression levels of Δ 1 ‐pyrroline‐5‐carboxylate synthase ( P5CS ) strongly decreased by a factor of 17.3 in the 70 PSU/0°C treatment, whereas copy numbers of ornithine δ‐aminotransferase (δ‐ OAT ) increased 7.6‐fold. Transcript levels of Δ 1 ‐pyrroline‐5‐carboxylate reductase ( P5CR ) and proline dehydrogenase ( ProDH ) were also slightly up‐regulated by 2.5 and 2.88, respectively. This contrasts with findings in higher plants where a reverse regulation of P5CS and δ‐OAT was observed and indicates that under elevated external salinities, the ornithine route is preferred to the glutamate pathway in F. cylindrus . Photosynthetic quantum yield at PSII instantly dropped from 0.61 to 0.24 after the upshift in salinity, which confirmed a detrimental effect of elevated salt concentrations on the photosynthetic machinery. Reduced photosynthetic energy capture might explain the preference for the ornithine route over the more energyconsuming proline route. Salt proved to be the dominating stressor, while an additional temperature decrease appeared to have an ameliorating effect.

Psychrophile

Proline dehydrogenase

Catabolism

Osmoregulation

Ornithine aminotransferase

10.1111/j.1529-8817.2007.00366.x

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Citations (82)

Effects of Grain Size and Humidity on Fretting Wear in Fine‐Grained Alumina, Al₂O₃/TiC, and Zirconia

Journal of the American Ceramic Society (1996)

Andreas Krell D. Klaffke

Friction and wear of sintered alumina with grain sizes between 0.4 and 3 μm were measured in comparison with Al 2 O 3 /TiC composites and with tetragonal ZrO 2 (3 mol% Y 2 O 3 ). The dependence on the grain boundary toughness and residual microstresses is investigated, and a hierarchical order of influencing parameters is observed. In air, reduced alumina grain sizes improve the micromechanical stability of the grain boundaries and the hardness, and reduced wear is governed by microplastic deformation, with few pullout events. Humidity and water slightly reduce the friction of all of the investigated ceramics. In water, this effect reduces the wear of coarser alumina microstructures. The wear of aluminas and of the Al 2 O 3 /TiC composite is similar; it is lower than observed in zirconia, where extended surface cracking occurs at grain sizes as small as 0.3 μm.

10.1111/j.1151-2916.1996.tb08565.x

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Citations (82)

Improved hardness and hierarchic influences on wear in submicron sintered alumina

Materials Science and Engineering A (1996)

Andreas Krell

10.1016/0921-5093(95)10155-1

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Citations (67)

Supplement Table 1) Ikaite content in ice cores from land fast and sea ice in East Antarctica during the SIPEX and DDU campaigns in 2007

Michael S. Fischer David N. Thomas Andreas Krell Gernot Nehrke Jörg Göttlicher

Table (database)

Ice core

10.1594/pangaea.847683

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