Science of entropy-stabilized ultra-high temperature thin films: Synthesis, validation and properties

The authors report on using multi-cathode magnetron sputtering to fabricate 5-component refractory carbides that are stabilized by configurational entropy to form a robust and high-temperature class of high temperature materials. Magnetron sputtering is an appealing fabrication method as one can prepare layers with high density and the compositional flexibility afforded by five independent metallic sources. Thin layers that comprise mixed carbides of the following elements: W, Mo, Ti, Hf, Zr, Ta, V, and Nb, will be discussed. In all cases sputtering is performed reactively in a gas atmosphere including Ar as the inert sputter gas and propane as the carbon source. Sputter depositions can be conducted between room temperature and 800 °C. The relationship between sputtering parameters including power, pressure, rate, gas mixture, and film properties including density, thermal conductivity, lattice constant, and phase evolution will be discussed. Please click Additional Files below to see the full abstract

Seawater carbonate chemistry and growth, carbon acquisition, and species interaction of Antarctic phytoplankton species in a laboratory experiment

Despite the fact that ocean acidification is considered to be especially pronounced in the Southern Ocean, little is known about CO2-dependent physiological processes and the interactions of Antarctic phytoplankton key species. We therefore studied the effects of CO2 partial pressure (PCO2) (16.2, 39.5, and 101.3 Pa) on growth and photosynthetic carbon acquisition in the bloom-forming species Chaetoceros debilis, Pseudo-nitzschia subcurvata, Fragilariopsis kerguelensis, and Phaeocystis antarctica. Using membrane-inlet mass spectrometry, photosynthetic O2 evolution and inorganic carbon (Ci) fluxes were determined as a function of CO2 concentration. Only the growth of C. debilis was enhanced under high PCO2. Analysis of the carbon concentrating mechanism (CCM) revealed the operation of very efficient CCMs (i.e., high Ci affinities) in all species, but there were species-specific differences in CO2-dependent regulation of individual CCM components (i.e., CO2 and uptake kinetics, carbonic anhydrase activities). Gross CO2 uptake rates appear to increase with the cell surface area to volume ratios. Species competition experiments with C. debilis and P. subcurvata under different PCO2 levels confirmed the CO2-stimulated growth of C. debilis observed in monospecific incubations, also in the presence of P. subcurvata. Independent of PCO2, high initial cell abundances of P. subcurvata led to reduced growth rates of C. debilis. For a better understanding of future changes in phytoplankton communities, CO2-sensitive physiological processes need to be identified, but also species interactions must be taken into account because their interplay determines the success of a species

Entwicklung eines Workflows für quantitative Datenauswertungen in R für die MINT-Didaktiken

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Coccolithophores do not increase particulate carbon production under nutrient limitation: A case study using Emiliania huxleyi (PML B92/11)

Abstract The coccolithophore Emiliania huxleyi (PML B92/11) was grown in batch culture under nitrogen (N) as well as phosphorus (P) limitation. Growth rate, particulate inorganic carbon (PIC), particulate organic carbon (POC), particulate organic nitrogen (PON), and particulate organic phosphorus (POP) production were determined. While PON production decreased by 96% under N-limitation and POP production decreased by 85% under P-limitation, growth rate decreased by 31% under N- and by 26% under P-limitation. POC production increased by a factor of 1.5 under N-limitation and by a factor of 3.3 under P-limitation. PIC production increased by a factor of 1.2 under N-limitation and did not change under P-limitation. It is concluded that the decrease in PON production under N-limitation and the decrease in POP production under P-limitation represent a physiological response of the cells while the increase in particulate carbon production represents a methodological artefact. The latter conclusion is based on a direct comparison of this strain's responses to nutrient limitation in different experimental setups, i.e., batch-, semi-continuous-, and continuous cultures

Innovative Hochschule Potsdam "Inno-Up"

Das Projekt Innovative Hochschule Potsdam – kurz Inno-UP – ist Teil der Bund-Länder-Initiative „Innovative Hochschule“. Es überträgt Ziele und Maßnahmen der Transferstrategie der Universität Potsdam strategisch, strukturell und operativ auf den Universitätscampus Potsdam-Golm. Der Wissens- und Technologietransfer aus Lehre und Forschung in die regionale Gesellschaft und Wirtschaft sollte nachhaltig gefördert werden. Um das zu erreichen, wurden die drei thematischen Schwerpunkte Technologiecampus, Bildungscampus und Gesellschaftscampus auf dem Universitätscampus Potsdam-Golm etabliert

Large-Scale Integrative Analysis of Epigenetic Modifications Induced by Isotretinoin, Doxycycline and Metronidazole in Murine Colonic Intestinal Epithelial Cells

Environmental factors are playing a central role in triggering inflammatory responses in the intestine. There is increasing evidence that the development of inflammatory bowel disease (IBD) is deriving from an aberrant immune response to the commensal gut microbiota triggered by various environmental factors in a susceptible host. A vitamin A derivate used in acne therapy (isotretinoin) has been inconsistently associated with the onset of IBD. However, what needs to be considered is the previous treatment of acne patients with antibiotics that are also associated with the development of IBD, thus representing a crucial confounding factor. Here, we studied whether doxycycline (acne therapy), metronidazole (IBD therapy) or isotretinoin are able to induce alterations in DNA methylation and microRNA expression patterns in murine colonic intestinal epithelial cells (IECs). Additionally, we analyzed time-dependent changes in the aforementioned epigenetic mechanisms to study how epigenetic signatures evolve over time. As for changes in DNA methylation, we found isotretinoin to have strong demethylating effects, while antibiotic treatment had only a moderate impact. Isotretinoin-mediated demethylation resolved after a washout phase, not supporting an association between isotretinoin treatment and IBD. Regarding microRNA and mRNA expression, isotretinoin and doxycycline, but not metronidazole, potentially induce long-term changes in microRNA/mRNA expression profiles towards the down-regulation of immune responses. Analysis of time-dependent DNA methylation showed stable marks over a time frame of 4 weeks. Furthermore, novel microRNAs were identified (e.g., microRNA-877-3p), which might be of relevance in IEC development