Connectivity and Synchronisation of Lake Ecosystems in Space and Time - CONNECT

Within the project CONNECT we are establishing a collaborative network between experts in remote sensing (RS) and freshwater ecology to study connectivity and coherence of lake ecosystems in a regional context at unprecedented temporal and spatial resolution. The overall aim is to understand the yet unexplained variation in phytoplankton dynamics among river-connected German lowland lakes, many of which are presently classified as in poor to bad ecological status. These lakes often face a high risk of eutrophication, mass development of harmful algal blooms, and high production of greenhouse gases. We suggest if measured on adequate temporal and spatial scales much of the among-lake variation in phytoplankton dynamics to be explained by the strength of hydrological lake-to-lake and lake-to-catchment connectivity as modulated by lake depth and mixing regime. This may have profound implications for the maximum intensity, spatial range and regional-scale magnitude of eutrophication impacts. We will use (i) a large-scale experimental manipulation of lake connectivity, and (ii) an observational field campaign contrasting deep and shallow river-connected lakes, to challenge this research frontier by an innovative combination of automatic high- frequency in situ measurements with state of the art near-to-far RS technology. Climate change is expected to alter the hydrology, and thus the connectivity of lake-river systems. However, it is also predicted to increase extreme weather events leading to an increased input of nutrients as well as colored dissolved organic matter (cDOM). By providing data of high spatio-temporal coverage, CONNECT will provide basic high quality data to better understand mechanisms of eutrophication at the local and regional scale. Our data, thus, provide a valuable basis to improve current management of such river-connected lake ecosystems under future climate scenarios. To reach this ambitious goal, the project will (i) build a cross- disciplinary collaborative network of excellence, (ii) develop a mechanistic understanding of lake ecosystem functioning at local and regional scale, (iii) improve future environmental monitoring and interpretation of available data from inland waters, and (iv) support more effective integrated management of river-connected lakes to mitigate eutrophication impacts

Granulocyte-colony stimulating factor for stroke treatment: mechanisms of action and efficacy in preclinical studies

G-CSF is widely employed for the treatment of chemotherapy-induced neutropenia. Recently, neuroprotective effects of G-CSF in animal stroke models were discovered including infarct size reduction and enhancement of functional recovery. The underlying mechanisms of action of G-CSF in ischemia appear to be a direct anti-apoptotic activity in neurons and a neurogenesis inducing capacity. Additional effects may be based on the stimulation of new blood-vessel formation, the stimulation of immunocompetence and -modulation as well as on bone marrow mobilization. In addition to a discussion of these mechanisms, we will review the available preclinical studies and analyze their impact on the overall efficacy of G-CSF in experimental stroke

Plasma-Oberflächenbehandlung von Flachsgeweben zur Verbesserung ihrer Imprägnierbarkeit

Thema der Arbeit ist die Vorbehandlung von Naturfasergeweben mit Atmosphärendruck-Plasma, um die Imprägnierbarkeit der Gewebe aufgrund plasmachemischer Veränderungen an deren Oberflächen zu verbessern. Hintergrund ist eine zunehmende Nutzung von Naturfasern als alternatives Verstärkungsmaterial in faserverstärkten Kunststoffen. Um der Absicht einer geringeren Umweltbelastung bei der Verwendung natürlicher Materialien Rechnung zu tragen, wurde hier auf den Einsatz nasschemischer Methoden verzichtet. Stattdessen wurde Plasma als trockenchemische Alternative verwendet. Für die Behandlungen wurde eine dielektrische Barriereentladung genutzt, mit der temperaturschonende Behandlungen im oberflächennahen Bereich von Materialien möglich sind. In der Arbeit wurden der Plasma-Behandlungsprozess entwickelt und grundlegende Untersuchungen an den behandelten Fasern durchgeführt. Zudem wurden verschiedene in-situ-Analysen zur weitergehenden Erklärung von Behandlungseffekten genutzt. Es zeigte sich unter anderem, dass eine beidseitig homogene Behandlung der genutzten Flachsgewebe durch geringfügige Anpassungen des Prozesses in einem Prozessschritt möglich ist. Durch einen kombinatorischen Wechselwirkungsmechanismus mit dem Plasma konnte die Benetzbarkeit und Kapillarität der Gewebe dabei deutlich erhöht werden. Mit Hilfe der Berechnung von elektrischen Feldern im Behandlungsraum konnten die Behandlungsergebnisse überdies weitergehend gedeutet werden. Die gewonnenen Erkenntnisse wurden daraufhin in einer modellhaften Beschreibung zusammengefasst, mit der die Veränderungen im Aufnahmeverhalten der Gewebe infolge der Plasmabehandlungen dargestellt werden können. Die Behandlungseffekte spiegelten sich ebenfalls in einer gesteigerten Aufnahme von Epoxidharz, folglich einem verbesserten Imprägnierverhalten, wieder. Zudem wurde gezeigt, dass verbesserte Kennwerte bei Verbundwerkstoffen erreicht werden können, wenn die Flachsgewebe zuvor plasmabehandelt werden

Treatment of Flax Fabric with AP-DBD in Parallel Plane Configuration

For the use of natural fibers in composite materials it is often necessary to improve the compatibility between fiber (sizing) and polymer matrix systems, e.g., by increasing the number of functional groups on the fiber surfaces. In this work, a dielectric barrier discharge (DBD) source in plane configuration is used to treat flax fabrics in ambient air. It is examined whether it is possible to increase the functionality on both fabric sides, which is achieved by simple changes in the DBD setup. After evaluating the treatment homogeneity of the filamentary plasma, an explanation for the treatment mechanism on the fiber surfaces is developed. It is shown that waxy substances, which naturally occur on natural fibers, play an important role in the wettability of the fabric

Atmospheric pressure plasma activation of natural fibres for improved matrix interaction: Abstrac presented at 16th International Conference on Plasma Surface Engineering, 17.-21.09.2018, Garmisch-Partenkirchen

Several investigations have shown that plasma activation is a suitable, environmental friendly method to modify fibre materials. Depending on the plasma chemistry, the surface energy and also the topography of fibres can be significantly changed which can lead to an improved wettability and surface chemistry. This is of particular interest during subsequent processing steps if fibres are implemented into fibre-reinforced polymers (FRPs).The processing of natural fibres is particularly difficult because their surface chemistry and topography are highly inhomogeneous and depend on the natural growth of the fibres. Additionally, the chemistry of cellulose, hemicellulose, pectin and lignin is not compatible with a lot of matrix systems. One possibility to improve the adhesion between natural fibres and matrix systems is to treat the fibres with cold plasma at atmospheric pressure. Hereby, beside a gentle surface cleaning, functional groups are formed on the fibre surfaces. Usually, the matrix material is often heated to lower its viscosity before impregnating the fibres. Therefore, it is important to know if the functional groups sustain the heat influence and still allow for a better impregnation. In this work surfaces of natural fibres were activated by a cold atmospheric pressure plasma source that offers a high treatment width and can be easily integrated into processing chains with regard to industrial applications. After activation the fibres were characterized by SEM, XPS, tensile testing and adapted wetting measurements by a Wilhelmy balance. Additionally, fibres were heated under defined atmospheres to simulate the temperature effects during the injection process. The results show an increase of oxygen containing groups and surface energy of the fibres after the plasma treatment. However, these activation effects were highly reduced after heating of the fibres. Thereby, the level of remaining activation effects depended on different plasma treatment parameters

An Arctic Ocean paleosalinity proxy from d2H of palmitic acid provides evidence for deglacial Mackenzie River flood events

The hydrogen isotopic composition (2H/1H, or d2H) of palmitic acid (PA) was measured in surface sediments from the Laptev and Kara Seas in the Russian Arctic to evaluate its use as a paleohydrographic proxy. d2HPA values in surface sediments varied by 118‰ over a 21 ppt range in mean annual surface salinity, and the two properties were highly correlated (R2 ¼ 0.8, p < 0.001) according to the relationship d2HPA ¼ 4.22 (±0.60)*S - 338 (±15). In contrast, d2H values of vascular plant wax n-alkanes (nC27, nC29, nC31) did not change systematically with salinity. These differing lipid d2H trends support the interpretation of PA as derived primarily from marine microalgae at these sites. Both the range and absolute values of d2HPA compared favorably to those predicted from published Arctic Ocean salinity and water isotope data and the expected response of d2HPA to salinity in cultured phytoplankton. Some 64e74% of the observed sedimentary d2HPA increase is estimated to have resulted from increasing d2Hwater values, with the remainder resulting from decreased 2H-discrimination during lipid biosynthesis at higher salinities. The large signal and high sensitivity of d2HPA to surface salinity changes in the Russian Arctic was exploited to test the hypothesis that floodwaters emanated from the Mackenzie River during the late deglacial period. Measurements of d2HPA were performed in a sediment core from the continental slope off the Mackenzie River in the Canadian Arctic. In samples from the top Bølling/Allerød-Younger Dryas period, reconstructed surface salinities (and d2HPA values) off the Mackenzie River declined from 20 ("253‰) to 16 ("269‰) before rebounding to 24 ("236‰) in the early Holocene, close to the modern value of ~25. A large salinity depression in the Canadian Arctic just prior to the start of the Younger Dryas would support the hypothesis of a northern routing of flood-waters from glacial Lake Agassiz via the Mackenzie River as a trigger for the Younger Dryas event