Niedermolekulare metallorganische Gelatoren : Desoxyaminozucker-Carbenkomplexe und Cholesterol-Titanocene

Im Rahmen dieser Arbeit konnte das Gebiet der niedermolekularen metallorganischen Gelatoren auf zur Gelierung befähigte Aminozucker- funktionalisierte Carbenkomplexe sowie Metallocene ausgedehnt werden. Mittels nicht-kovalenter Wechselwirkungen (Wasserstoffbrückenbindungen, van-der-WaalsKräfte, pi-pi-Wechselwirkungen) aggregieren die Moleküle, bilden Nanostrukturen und Netzwerke in Lösungsmitteln verschiedener Polaritäten aus. Es kommt somit zur Gelierung der Solventien. Diese dargestellten Verbindungen besitzen zumeist amphiphile Strukturen, so dass in dieser Arbeit weitere metallorganische Amphiphile dargestellt und in mehreren Fällen erfolgreich auf Gelbildungseigenschaften untersucht wurden. Des Weiteren werden in dieser Dissertation Cholesterol-substituierte Titanocendichloride vorgestellt. Bei diesen handelt es sich um die ersten metallorganischen ALS-Gelatoren. Diese wurden auf Gelierungs- sowie katalytische Eigenschaften hin untersucht. Durch Variation der Substitutionsmuster der Titanocene sowie Strukturveränderungen an den amphiphilen Aminozucker-funktionalisierten Carbenkomplexen ließen sich Struktur-Gelbildungs-Korrelationen ableiten. Die supramolekularen nicht-racemischen Nanostrukturen der Gele wurden mittels komplementärer spektroskopischer und analytischer Verfahren (NMR-, CD-, SAXS-, TEM-, AFM, SEM-Messungen) untersucht. Folglich konnten Rückschlüsse auf die Aggregationsphänomene der Verbindungen gezogen werden. Darüber hinaus wurden mittels der oben beschriebenen Verfahren Aggregationsmodelle vorgeschlagen. Diese Arbeit zeigt die Erweiterung des Gebietes der metallorganischen Gelatoren. Die Entwicklung der Aggregationsmodelle hilft, das Phänomen der Gelierung zu verstehen und neuartige funktionalisierte Verbindungen zu synthetisieren.</p

LEGaTO: first steps towards energy-efficient toolset for heterogeneous computing

LEGaTO is a three-year EU H2020 project which started in December 2017. The LEGaTO project will leverage task-based programming models to provide a software ecosystem for Made-in-Europe heterogeneous hardware composed of CPUs, GPUs, FPGAs and dataflow engines. The aim is to attain one order of magnitude energy savings from the edge to the converged cloud/HPC.Peer ReviewedPostprint (author's final draft

LEGaTO: towards energy-efficient, secure, fault-tolerant toolset for heterogeneous computing

LEGaTO is a three-year EU H2020 project which started in December 2017. The LEGaTO project will leverage task-based programming models to provide a software ecosystem for Made-in-Europe heterogeneous hardware composed of CPUs, GPUs, FPGAs and dataflow engines. The aim is to attain one order of magnitude energy savings from the edge to the converged cloud/HPC.Peer ReviewedPostprint (author's final draft

Influence of application techniques on the ecotoxicological effects of nanomaterials in soil

Background: In terrestrial ecotoxicological tests, the availability and ecotoxicity of solid nanomaterials may depend on the application technique. We compared five spiking procedures using solid uncoated TiO2 and Ag nanoparticles in standardized OECD tests with earthworms, plants and soil microflora: dry spiking of soil by applying soil or silica sand as a carrier; dry spiking of food without a carrier; and wet spiking of soil and food with an aqueous nanoparticle dispersion. Results: The effects of the nanomaterials were influenced by the application technique. The differences were independent of the test organism (which represented different habitats and exposure pathways) and the specificity of the effect (stimulation or inhibition). Wet spiking resulted in stronger effects than dry spiking, but the bioavailability of the particles appeared to be limited when highly-concentrated nanoparticle suspensions were used for wet spiking. The availability of the nanoparticles was slightly lower when silica sand rather than soil was used as the carrier for dry spiking, but the matrix itself (soil or food) had no effect. Conclusion: There are indications that the concentrations of the stock suspensions influence the test results, so dry spiking is preferred for solid TiO2 and Ag nanoparticles. We achieved satisfactory spiking homogeneity with Ag nanoparticles using soil as a solid carrier. Further experiments with other carriers and soil types are required to confirm that the observed differences are universal in character. There was no difference in effect when TiO2 nanoparticles were applied via food or soil. The spiking of soil instead of food is preferred for TiO2 nanoparticles, as is the case for conventional chemicals

Influence of application techniques on the ecotoxicological effects of nanomaterials in soil

Abstract Background: In terrestrial ecotoxicological tests, the availability and ecotoxicity of solid nanomaterials may depend on the application technique. We compared five spiking procedures using solid uncoated TiO 2 and Ag nanoparticles in standardized OECD tests with earthworms, plants and soil microflora: dry spiking of soil by applying soil or silica sand as a carrier; dry spiking of food without a carrier; and wet spiking of soil and food with an aqueous nanoparticle dispersion

Determination of low environmental free cyanide concentrations in freshwaters

Cyanide compounds are naturally emitted into the environment in low levels by degradation processes or emitted from anthropogenic sources. In surface water, complex cyanide compounds as well as 'free cyanide' are present. The latter term covers hydrogen cyanide and cyanide compounds which easily liberate hydrogen cyanide under slightly acidic conditions. Especially free cyanide may cause adverse effects in the environment. To exclude negative impacts on freshwater systems, in the context of the European Water Framework Directive (WFD), preventive regulatory activities for free cyanide are currently under discussion. However, established analytical methods for quantification of free cyanide only obtain limits of quantification (LOQs) in the range of 1 μg 

Hazard assessment of a silver nanoparticle in soil applied via sewage sludge

Background: Silver nanoparticles (AgNPs) are widely used in many fields of application and consumer products due to their antibacterial properties. The aim of this study was to prepare a hazard assessment for one specific AgNP in soil, incorporated via sewage sludge (the sewage sludge pathway). The effects of pristine AgNPs on microorganisms, plants and earthworms were first determined in screening tests. Long-term tests over 140 days were then conducted with AgNPs added to soil via sewage sludge. AgNPs were incorporated into the sludge through a simulated sewage treatment plant (STP) over 10 days to allow transformation to occur and also by manual spiking over 2 h. The results of the most sensitive organism from the long-term tests, the soil microorganisms, are presented. Results: The STP simulations confirmed that at environmentally relevant concentrations >90% of AgNPs remain bound to sewage sludge. Effects of AgNPs bound to sewage sludge and added to soil were similar to that of pristine NM-300K after degradation of the sludge. The predicted no-effect concentration for NM-300K in soil of 0.05 mg/kg dry soil determined a maximum threshold of 30 mg/kg dry sludge per application, considering the maximum addition of sewage sludge in Germany (5 tons per hectare every 3 years). Conclusion: At environmentally relevant concentrations, AgNP absorption to sludge and aging in soil (even after transformation) cause toxic effects on soil microorganisms of the terrestrial ecosystem

Comparative analysis of the transcriptome responses of zebrafish embryos after exposure to low concentrations of cadmium, cobalt and copper

Metal toxicity is a global environmental challenge. Fish are particularly prone to metal exposure, which can be lethal or cause sublethal physiological impairments. The objective of this study was to investigate how adverse effects of chronic exposure to non-toxic levels of essential and non-essential metals in early life stage zebrafish may be explained by changes in the transcriptome. We therefore studied the effects of three different metals at low concentrations in zebrafish embryos by transcriptomics analysis. The study design compared exposure effects caused by different metals at different developmental stages (pre-hatch and post-hatch). Wild-type embryos were exposed to solutions of low concentrations of copper (CuSO4), cadmium (CdCl2) and cobalt (CoSO4) until 96 h post-fertilization (hpf) and microarray experiments were carried out to determine transcriptome profiles at 48 and 96 hpf. We found that the toxic metal cadmium affected the expression of more genes at 96 hpf than 48 hpf. The opposite effect was observed for the essential metals cobalt and copper, which also showed enrichment of different GO terms. Genes involved in neuromast and motor neuron development were significantly enriched, agreeing with our previous results showing motor neuron and neuromast damage in the embryos. Our data provide evidence that the response of the transcriptome of fish embryos to metal exposure differs for essential and non-essential metals

Concentration dependent transcriptome responses of zebrafish embryos after exposure to cadmium, cobalt and copper

Environmental metals are known to cause harmful effects to fish of which many molecular mechanisms still require elucidation. Particularly concentration dependence of gene expression effects is unclear. Focusing on this matter, zebrafish embryo toxicity tests were used in combination with transcriptomics. Embryos were exposed to three concentrations of copper (CuSO4), cadmium (CdCl2) and cobalt (CoSO4) from just after fertilization until the end of the 48hpf pre- and 96hpf post-hatch stage. The RNA was then analyzed on Agilent's Zebrafish (V3, 4×44K) arrays. Enrichment for GO terms of biological processes illustrated for cadmium that most affected GO terms were represented in all three concentrations, while for cobalt and copper most GO terms were represented in the lowest test concentration only. This suggested a different response to the non-essential cadmium than cobalt and copper. In cobalt and copper treated embryos, many developmental and cellular processes as well as the Wnt and Notch signaling pathways, were found significantly enriched. Also, different exposure concentrations affected varied functional networks. In contrast, the largest clusters of enriched GO terms for all three concentrations of cadmium included responses to cadmium ion, metal ion, xenobiotic stimulus, stress and chemicals. However, concentration dependence of mRNA levels was evident for several genes in all metal exposures. Some of these genes may be indicative of the mechanisms of action of the individual metals in zebrafish embryos. Real-time quantitative RT-PCR (qRT-PCR) verified the microarray data for mmp9, mt2, cldnb and nkx2.2a

Sweep Dynamics (SD) plots: Computational identification of selective sweeps to monitor the adaptation of influenza A viruses

Abstract Monitoring changes in influenza A virus genomes is crucial to understand its rapid evolution and adaptation to changing conditions e.g. establishment within novel host species. Selective sweeps represent a rapid mode of adaptation and are typically observed in human influenza A viruses. We describe Sweep Dynamics (SD) plots, a computational method combining phylogenetic algorithms with statistical techniques to characterize the molecular adaptation of rapidly evolving viruses from longitudinal sequence data. SD plots facilitate the identification of selective sweeps, the time periods in which these occurred and associated changes providing a selective advantage to the virus. We studied the past genome-wide adaptation of the 2009 pandemic H1N1 influenza A (pH1N1) and seasonal H3N2 influenza A (sH3N2) viruses. The pH1N1 influenza virus showed simultaneous amino acid changes in various proteins, particularly in seasons of high pH1N1 activity. Partially, these changes resulted in functional alterations facilitating sustained human-to-human transmission. In the evolution of sH3N2 influenza viruses, we detected changes characterizing vaccine strains, which were occasionally revealed in selective sweeps one season prior to the WHO recommendation. Taken together, SD plots allow monitoring and characterizing the adaptive evolution of influenza A viruses by identifying selective sweeps and their associated signatures