Twin-roller quenching of Bi2Sr2Ca2Cu3O10 melts

Melts of the target composition Bi2Sr2Ca2Cu3O10 were produced and quenched in a specially designed twin-roller device. Quenching rates were estimated to be between about 0.2 ∙ 10^6 and 2 ∙ 10^6 K ∙ s^-1. In all quenching experiments mainly three sample shapes resulted, thin slivers, fibers, and clusters of sticking droplets. Slivers and fibers proved to be glassy, whereas the bulk of the clusters was crystalline. The slivers showed surface features due to nonuniform solidification processes. Thus wavy regions could be found or the surfaces were layered because of a rupturing during quenching. It could further be shown that an AI2O3 content of the melts does have some influence on the glass formation

Mass Balances of a Drained and a Rewetted Peatland: on Former Losses and Recent Gains

Drained peatlands are important sources of greenhouse gases and are rewetted to curb these emissions. We study one drained and one rewetted fen in terms of losses—and, after rewetting—gains of organic matter (OM), carbon (C), and peat thickness. We determined bulk density (BD) and ash/OM (and C/OM) ratios for 0.5 cm thick contiguous slices from peat monoliths to calculate losses. Whereas one site has lost 28.5 kg OM m−2 corresponding to annual emissions of ~10 t CO2 ha−1 a−1 over 50 years of effective drainage, the other site has lost 102 kg OM m−2, corresponding to an annual loss of ~30 t CO2 ha−1 a−1 for 30 years of intensive drainage and 6 t CO2 ha−1 a−1 during ~225 years of weak drainage before that. Height losses ranged from 43 to 162 cm. In the 20 years after rewetting, 2.12 kg C m−2 was accumulated, equaling an average annual uptake of ~0.4 kg CO2 m−2 a−1. The results indicate that rewetting can lead to carbon accumulation in fens. This sink function is only small compared with the high emissions that are avoided through rewetting

Erstellung eines Leitfadens zur Verarbeitung und zum Anbau von ökologischem Dinkel

Ziel des Projekts war die Stärkung der Wertschöpfungskette für in Deutschland erzeugten Dinkel. Dazu sollten Basisspezifikationen für die Qualität von Speisedinkel und Empfehlungen für Anbau und bäckerische Verarbeitung erarbeitet werden, mit deren Hilfe in der Praxis die Produktionssicherheit und Produktqualität verbessert werden können. Grundlage dafür sollten die spezifischen Eigenschaften von Dinkel im Allgemeinen sowie den untersuchten Sorten im Besonderen sein. Zunächst wurden Praxis-Gebäckproben untersucht, um eine Zielqualität festzulegen. Darauf folgte die Untersuchung von rund 150 Praxis-Getreideproben aus ganz Deutschland. Dabei handelte es sich zur Hälfte um Dinkel der Sorte „Oberkulmer Rotkorn“, zur Hälfte um „Franckenkorn“. Bestimmt wurden die sensorischen Eigenschaften, Analysewerte sowie die rheologischen Eigenschaften. Außerdem wurden Vermahlungs- und Backversuche durchgeführt. Ein Standardverfahren zur Entspelzung und Vermahlung von Dinkel im Labormaßstab wurde entwickelt. Verschiedene Methoden und Mehltypen wurden bewertet im Hinblick darauf, wie aussagekräftig sie in Bezug auf die Proteinqualität des Dinkels sind. Für die Charakterisierung der Backqualität wurden Öko-Standard-Backversuche sowohl für Vollkornmehl als auch für Typenmehl angepasst für Dinkel entwickelt. Ergebnis aus dem Vergleich im Standard-Backversuch ist eine bessere Backqualität von „Franckenkorn“. „Oberkulmer Rotkorn“ zeigt stärkere Qualitätsschwankungen bei ungünstigen Witterungsverhältnissen im Anbau. Beide Sorten lassen sich jedoch mit angepasstem Vorgehen zufriedenstellend verbacken. Hierzu wurden Optimierungsversuche durchgeführt. Variiert wurden der Verarbeitungsprozess an sich (Teigruhezeit, Temperatur), der Zutateneinsatz sowie das eingesetzte Mehl (Mischung aus beiden Dinkelsorten). Eingesetzt wurden nur Zutaten, die entsprechend den Richtlinien der deutschen Öko-Anbauverbände zulässig sind. Für jede Probe wurden die Untersuchungsergebnisse in Verbindung mit Daten zu Standort und Anbaumaßnahmen ausgewertet. Ein Praxis-Leitfaden „Biodinkel“ wurde in der Reihe der FiBL-Merkblätter veröffentlicht

Chancen und Risiken im Kontext von Migration und Adoleszenz: eine Fallstudie

"Der Beitrag erörtert die adoleszenten Spielräume von jungen Migrant/innen in Deutschland hinsichtlich der Ermöglichung oder Verhinderung individueller Entwicklungs- und Bildungsprozesse. Vor dem Hintergrund der empirischen Erhebungen einer bi-nationalen Studie werden die Herausforderungen diskutiert, die jugendliche Migrant/innen beim Durchlaufen dieses verdoppelten Transformationsprozesses zu bewältigen haben und die involvierten Ressourcen und Hindernisse betrachtet. Anhand des Fallbeispiels einer jungen, studierenden 'Spätaussiedlerin' aus Russland wird exemplarisch rekonstruiert, wie sich die Migrationsbedingungen der betroffenen Familie und deren sozial-psychologische Bearbeitung auf die Erfahrungen der Jugendlichen mit der Ankunftsgesellschaft auswirken und welche Chancen und Risiken innerhalb der adoleszenten Entwicklungsprozesse auftauchen können, die zu bewältigen sind." (Autorenreferat)"The article discusses the adolescent opportunity structures of young immigrants in Germany with regard to enabling or preventing of individual developmental and educational processes. The challenges young immigrants have to face during their twofold transformation process are discussed and the resources and obstacles involved studied against the background of the empirical results of a bi-national study. A case study of a young, university-enrolled 'Spätaussiedlerin' from Russia is used to reconstruct how the migration conditions of the family in question and its socio-psychological coping capacities may influence the experiences of the young adolescent with the German society and the opportunities and risks in adolescent development processes that have to be dealt with." (author's abstract

Long-Term Rewetting of Three Formerly Drained Peatlands Drives Congruent Compositional Changes in Pro- and Eukaryotic Soil Microbiomes through Environmental Filtering

Drained peatlands are significant sources of the greenhouse gas (GHG) carbon dioxide.Rewetting is a proven strategy used to protect carbon stocks; however, it can lead to increasedemissions of the potent GHG methane. The response to rewetting of soil microbiomes as drivers ofthese processes is poorly understood, as are the biotic and abiotic factors that control communitycomposition. We analyzed the pro- and eukaryotic microbiomes of three contrasting pairs ofminerotrophic fens subject to decade-long drainage and subsequent long-term rewetting. Abiotic soilproperties including moisture, dissolved organic matter, methane fluxes, and ecosystem respirationrates were also determined. The composition of the microbiomes was fen-type-specific, but allrewetted sites showed higher abundances of anaerobic taxa compared to drained sites. Based onmulti-variate statistics and network analyses, we identified soil moisture as a major driver ofcommunity composition. Furthermore, salinity drove the separation between coastal and freshwaterfen communities. Methanogens were more than 10-fold more abundant in rewetted than in drainedsites, while their abundance was lowest in the coastal fen, likely due to competition with sulfatereducers. The microbiome compositions were reflected in methane fluxes from the sites. Our resultsshed light on the factors that structure fen microbiomes via environmental filtering

A decellularized human corneal scaffold for anterior corneal surface reconstruction

Abstract Allogenic transplants of the cornea are prone to rejection, especially in repetitive transplantation and in scarred or highly vascularized recipient sites. Patients with these ailments would particularly benefit from the possibility to use non-immunogenic decellularized tissue scaffolds for transplantation, which may be repopulated by host cells in situ or in vitro. So, the aim of this study was to develop a fast and efficient decellularization method for creating a human corneal extracellular matrix scaffold suitable for repopulation with human cells from the corneal limbus. To decellularize human donor corneas, sodium deoxycholate, deoxyribonuclease I, and dextran were assessed to remove cells and nuclei and to control tissue swelling, respectively. We evaluated the decellularization effects on the ultrastructure, optical, mechanical, and biological properties of the human cornea. Scaffold recellularization was studied using primary human limbal epithelial cells, stromal cells, and melanocytes in vitro and a lamellar transplantation approach ex vivo. Our data strongly suggest that this approach allowed the effective removal of cellular and nuclear material in a very short period of time while preserving extracellular matrix proteins, glycosaminoglycans, tissue structure, and optical transmission properties. In vitro recellularization demonstrated good biocompatibility of the decellularized human cornea and ex vivo transplantation revealed complete epithelialization and stromal repopulation from the host tissue. Thus, the generated decellularized human corneal scaffold could be a promising biological material for anterior corneal reconstruction in the treatment of corneal defects

Bacterial porin disrupts mitochondrial membrane potential and sensitizes host cells to apoptosis

The bacterial PorB porin, an ATP-binding beta-barrel protein of pathogenic Neisseria gonorrhoeae, triggers host cell apoptosis by an unknown mechanism. PorB is targeted to and imported by host cell mitochondria, causing the breakdown of the mitochondrial membrane potential (delta psi m). Here, we show that PorB induces the condensation of the mitochondrial matrix and the loss of cristae structures, sensitizing cells to the induction of apoptosis via signaling pathways activated by BH3-only proteins. PorB is imported into mitochondria through the general translocase TOM but, unexpectedly, is not recognized by the SAM sorting machinery, usually required for the assembly of beta-barrel proteins in the mitochondrial outer membrane. PorB integrates into the mitochondrial inner membrane, leading to the breakdown of delta psi m. The PorB channel is regulated by nucleotides and an isogenic PorB mutant defective in ATP-binding failed to induce delta psi m loss and apoptosis, demonstrating that dissipation of delta psi m is a requirement for cell death caused by neisserial infection