Einlaufverhalten nasslaufender Lamellenkupplungen im Schlupfbetrieb

Forschung im Ingenieurwesen - Nasslaufende Lamellenkupplungen weisen zu Betriebsbeginn eine Phase des Einlaufens auf, in der sich das Reibungsverhalten durch Anpassung der Reibflächen...     

Assessment of Bone Microstructure by Micro CT in C57BL/6J Mice for Sex-Specific Differentiation

It remains uncertain which skeletal sites and parameters should be analyzed in rodent studies evaluating bone health and disease. In this cross-sectional mouse study using micro-computed tomography (µCT), we explored: (1) which microstructural parameters can be used to discriminate female from male bones and (2) whether it is meaningful to evaluate more than one bone site. Microstructural parameters of the trabecular and/or cortical compartments of the femur, tibia, thoracic and lumbar vertebral bodies, and skull were evaluated by µCT in 10 female and 10 male six-month-old C57BL/6J mice. The trabecular number (TbN) was significantly higher, while the trabecular separation (TbSp) was significantly lower in male compared to female mice at all skeletal sites assessed. Overall, bone volume/tissue volume (BV/TV) was also significantly higher in male vs. female mice (except for the thoracic spine, which did not differ by sex). Most parameters of the cortical bone microstructure did not differ between male and female mice. BV/TV, TbN, and TbSp at the femur, and TbN and TbSp at the tibia and lumbar spine could fully (100%) discriminate female from male bones. Cortical thickness (CtTh) at the femur was the best parameter to detect sex differences in the cortical compartment (AUC = 0.914). In 6-month-old C57BL/6J mice, BV/TV, TbN, and TbSp can be used to distinguish male from female bones. Whenever it is not possible to assess multiple bone sites, we propose to evaluate the bone microstructure of the femur for detecting potential sex differences.     

Tomato Sterol 22-desaturase Gene CYP710A11: Its Roles in Meloidogyne incognita Infection and Plant Stigmasterol Alteration

Sterols are isoprenoid-derived lipids that play essential structural and functional roles in eukaryotic cells. Plants produce a complex mixture of sterols, and changes in plant sterol profiles have been linked to plant–pathogen interactions. β-Sitosterol and stigmasterol, in particular, have been associated with plant defense. As nematodes have lost the ability to synthesize sterols de novo, they require sterols from the host. Tomato (Solanum lycopersicum) plants infected by the plant parasitic nematode Meloidogyne incognita show a reduced level of stigmasterol and a repression of the gene CYP710A11, encoding the sterol C-22 desaturase that is responsible for the conversion of β-sitosterol to stigmasterol. In this study, we investigated the role of the tomato sterol C-22 desaturase gene CYP710A11 in the response to infection by M. incognita. We explored the plant–nematode interaction over time by analyzing the plant sterol composition and CYP710A11 gene regulation in S. lycopersicum after M. incognita infection. The temporal gene expression analysis showed that 3 days after inoculation with M. incognita, the CYP710A11 expression was significantly suppressed in the tomato roots, while a significant decrease in the stigmasterol content was observed after 14 days. A cyp710a11 knockout mutant tomato line lacking stigmasterol was analyzed to better understand the role of CYP710A11 in nematode development. M. incognita grown in the mutant line showed reduced egg mass counts, presumably due to the impaired growth of the mutant. However, the nematodes developed as well as they did in the wild-type line. Thus, while the suppression of CYP710A11 expression during nematode development may be a defense response of the plant against the nematode, the lack of stigmasterol did not seem to affect the nematode. This study contributes to the understanding of the role of stigmasterol in the interaction between M. incognita and tomato plants and shows that the sterol C-22 desaturase is not essential for the success of M. incognita.     

Wärmeleitfähigkeit eines Gemisches von Metallkugeln und ÖI

Zusammenfassung Die W?rmeleitf?higkeit von Gemischen aus festen und flüssigen Stoffen in Abh?ngigkeit von der W?rmeleitf?higkeit der Füllstoffe wird bestimmt Diese Arbeit wurde ausgeführt unter Leitung von Prof. Dr.Hase, dem ich für die Anregung zu der Arbeit und seine stete Hilfsbereitschaft herzlich danke.     

Reinforcement of a Magnesium‐Ammonium‐Phosphate Cement with Calcium Phosphate Whiskers

Self‐setting resorbable phosphate cements are characterized by an excellent biocompatibility and bioactivity. However, poor mechanical properties restrict their application. Most studies which characterize phosphate cements mechanically focus on strength measurements. Examinations of mechanical reliability and facture toughness were hardly performed. In this study, calcium phosphate whisker‐reinforced magnesium‐ammonium‐phosphate (struvite) cements were examined at the whisker–matrix interface and the measured strength, reliability and toughness values were correlated to these observations. Moreover, the toughening mechanisms were evaluated. It was shown that whisker incorporation is not beneficial for material strength. It led to a strength decrease from 29.8 to 21.8 MPa by the incorporation of 15 vol% calcium‐deficient hydroxyapatite (CDHA) whiskers compared to the pure struvite cement. Weibull statistics and microstructural observations revealed that this is caused by the whisker–matrix interface, which acts as a flaw. In contrast with that, the reliability increases upon whisker incorporation. Furthermore, the critical stress intensity factor K_IC as well as the work‐of‐fracture γ_wof increase from 0.52 to 0.60 MPam^1/2 and from 9.5 to 12.9 J/m² by the addition of 15 vol% CDHA whiskers compared to the original struvite cement. It was shown that whisker pull‐out and crack deflection are the main mechanisms responsible for this increase.     

Aryl Bis‐Sulfonamide Inhibitors of IspF from Arabidopsis thaliana and Plasmodium falciparum

2‐Methylerythritol 2,4‐cyclodiphosphate synthase (IspF) is an essential enzyme for the biosynthesis of isoprenoid precursors in plants and many human pathogens. The protein is an attractive target for the development of anti‐infectives and herbicides. Using a photometric assay, a screen of 40 000 compounds on IspF from Arabidopsis thaliana afforded symmetrical aryl bis‐sulfonamides that inhibit IspF from A. thaliana (AtIspF) and Plasmodium falciparum (PfIspF) with IC₅₀ values in the micromolar range. The ortho‐bis‐sulfonamide structural motif is essential for inhibitory activity. The best derivatives obtained by parallel synthesis showed IC₅₀ values of 1.4 μm against PfIspF and 240 nm against AtIspF. Substantial herbicidal activity was observed at a dose of 2 kg ha^?1. Molecular modeling studies served as the basis for an in silico search targeted at the discovery of novel, non‐symmetrical sulfonamide IspF inhibitors. The designed compounds were found to exhibit inhibitory activities in the double‐digit micromolar IC₅₀ range.     

A comparative analysis of EIA practice for wastewater treatment plants in great Britain and Germany

This article reports the findings of an investigation of the practice of environmental impact assessment (EIA) for wastewater treatment plants in the United Kingdom and Germany. It demonstrates that both EIA systems have a number of common deficiencies but that the differences between the practice of EIA in Britain and Germany are considerable. These indicate that one of the objectives of the European Directive—to harmonize environmental controls—has not been met. The differences can be explained by examining: (1) the context in which EIAs for wastewater treatment plants take place in both countries; (2) the ways in which EIA procedures are implemented in both countries; and (3) the attitudes of the competent authorities in both countries to EIA.     

Trends in the production and storage of fresh meat – the holistic approach to bacteriological meat quality

The aim of this review paper is to introduce readers to the modern approach to meat production as recommended by public authorities. No part of the food chain can be regarded alone but has to be seen as part of the whole. A holistic approach to fresh meat storage and retailing must therefore start with the living animal and cannot end with the sale of the meat. It must also include the consumers. One of the highest priority issues for consumers, producers and governments is food safety, and with it, consumer safety. Here we briefly describe the possibilities of keeping initial amounts of bacteria in meat low and modern storage of fresh meat. In future, the consumer must be incorporated in the meat food chain.     

Musik und Informatik

Ohne Zusammenfassung