Polymeric Materials in Solar-thermal Systems - Performance Requirements and Loads

AbstractA major basic problem in selecting appropriate polymeric materials and processing technology routes is related to the lack of well-defined functional and performance requirements on the component level and to material property requirements on the specimen level.Hence, in a first step several reference climate regions were defined for pumped systems (continental (Graz/Austria), moderate climate (Beijing/China)) and non-pumped systems (Mediterranean (Athens/Greece), hot and dry (Pretoria/South Africa), hot and humid (Fortaleza/Brazil)), respectively. For each of these reference regions various solar-thermal plant types (e.g., domestic hot-water systems for single family houses (pumped and thermosiphon); domestic hot-water systems for multi-family houses; solar combi-systems for domestic hot-water and space heating (pumped) were pre-defined and evaluated and optimized virtually by modelling and simulation.To determine performance requirements on the component level and to derive material property requirements on the specimen level all-purpose modelling and design tools for collectors were implemented and used which allow for the description of temperature profiles, stagnation conditions, efficiency curves, pressure losses, distribution of fluid and heat flow and the thermal and hydraulic optimisation of the whole collector

Betonieren unter Verkehr: Untersuchung der Auswirkungen von Erschütterungen auf jungen Beton

Im vorgestellten Beitrag wird der Einfluss von Erschütterungen auf den jungen Beton systematisch und anhand von realistischen Versuchen an Kleinkörpern aus unbewehrtem und bewehrtem Beton behandelt. Die kontrollierte dynamische Anregung erfolgt künstlich mit dem AIT-Schwingungsgenerator. Die Proben (zwei verschiedene Betonsorten: „Standard-Brückenbeton“ B3-C30/37 und „Randbalkenbeton“ B7-C25/30) werden während der Erhärtungsphase systematisch mit harmonischen als auch mit realen verkehrsinduzierten Brückenschwingungsverläufen beaufschlagt. Variiert werden Intensitäten und Frequenzgehalt sowie Signalform. Im Anschluss werden die Materialparameter bestimmt und mit ruhend gelagerten Referenzköpern verglichen. Erste Ergebnisse zeigen, dass die mechanischen Eigenschaften Druckfestigkeit und E-Modul wenig oder nur gering beeinflusst werden. Dauerhaftigkeitstests und Untersuchungen am Mikrogefüge dienen dazu, Fehler, Risse und Veränderungen im Gefüge zu identifizieren und werden im laufenden Forschungsprojekt noch weiter durchgeführt. Auswirkungen auf den Verbund zwischen Beton und Bewehrung werden durch Auszugversuche analysiert. Bei diesen Versuchen wurden bei größeren Relativbewegungen zwischen Beton und Bewehrungsstab Abnahmen der mittleren Verbundfestigkeit beobachtet. Bei geringeren Relativverschiebungen (Amplituden von ca. 0,14 mm bei Dauerverkehr) konnte die Verbundfestigkeit hingegen sogar gesteigert werden

Assembly of custom TALE-type DNA binding domains by modular cloning

Transcription activator-like effector (TALE) DNA binding proteins show tremendous potential as molecular tools for targeted binding to any desired DNA sequence. Their DNA binding domain consists of tandem arranged repeats, and due to this repetitive structure it is challenging to generate designer TALEs (dTALEs) with user-defined specificity. We present a cloning approach that facilitates the assembly of multiple repeat-encoding DNA fragments that translate into dTALEs with pre-defined DNA binding specificity. This method makes use of type IIS restriction enzymes in two sequential cut-ligase reactions to build dTALE repeat arrays. We employed this modular approach for generation of a dTALE that differentiates between two highly similar DNA sequences that are both targeted by the Xanthomonas TALE, AvrBs3. These data show that this modular assembly system allows rapid generation of highly specific TALE-type DNA binding domains that target binding sites of predefined length and sequence. This approach enables the rapid and flexible production of dTALEs for gene regulation and genome editing in routine and high-throughput applications

The Molecular Diversity of Freshwater Picoeukaryotes Reveals High Occurrence of Putative Parasitoids in the Plankton

Eukaryotic microorganisms have been undersampled in biodiversity studies in freshwater environments. We present an original 18S rDNA survey of freshwater picoeukaryotes sampled during spring/summer 2005, complementing an earlier study conducted in autumn 2004 in Lake Pavin (France). These studies were designed to detect the small unidentified heterotrophic flagellates (HF, 0.6–5 µm) which are considered the main bacterivores in aquatic systems. Alveolates, Fungi and Stramenopiles represented 65% of the total diversity and differed from the dominant groups known from microscopic studies. Fungi and Telonemia taxa were restricted to the oxic zone which displayed two fold more operational taxonomic units (OTUs) than the oxycline. Temporal forcing also appeared as a driving force in the diversification within targeted organisms. Several sequences were not similar to those in databases and were considered as new or unsampled taxa, some of which may be typical of freshwater environments. Two taxa known from marine systems, the genera Telonema and Amoebophrya, were retrieved for the first time in our freshwater study. The analysis of potential trophic strategies displayed among the targeted HF highlighted the dominance of parasites and saprotrophs, and provided indications that these organisms have probably been wrongfully regarded as bacterivores in previous studies. A theoretical exercise based on a new ‘parasite/saprotroph-dominated HF hypothesis’ demonstrates that the inclusion of parasites and saprotrophs may increase the functional role of the microbial loop as a link for carbon flows in pelagic ecosystems. New interesting perspectives in aquatic microbial ecology are thus opened

Anti-Biofilm Compounds Derived from Marine Sponges

Bacterial biofilms are surface-attached communities of microorganisms that are protected by an extracellular matrix of biomolecules. In the biofilm state, bacteria are significantly more resistant to external assault, including attack by antibiotics. In their native environment, bacterial biofilms underpin costly biofouling that wreaks havoc on shipping, utilities, and offshore industry. Within a host environment, they are insensitive to antiseptics and basic host immune responses. It is estimated that up to 80% of all microbial infections are biofilm-based. Biofilm infections of indwelling medical devices are of particular concern, since once the device is colonized, infection is almost impossible to eliminate. Given the prominence of biofilms in infectious diseases, there is a notable effort towards developing small, synthetically available molecules that will modulate bacterial biofilm development and maintenance. Here, we highlight the development of small molecules that inhibit and/or disperse bacterial biofilms specifically through non-microbicidal mechanisms. Importantly, we discuss several sets of compounds derived from marine sponges that we are developing in our labs to address the persistent biofilm problem. We will discuss: discovery/synthesis of natural products and their analogues—including our marine sponge-derived compounds and initial adjuvant activity and toxicological screening of our novel anti-biofilm compounds

The periplasmic HrpB1 protein from Xanthomonas spp. binds to peptidoglycan and to components of the type III secretion system

The plant-pathogenic bacterium Xanthomonas campestris pv. vesicatoria employs a type III secretion (T3S) system to translocate bacterial effector proteins into eukaryotic host cells. The membrane-spanning secretion apparatus consists of 11 core components and several associated proteins with yet unknown functions. In this study, we analyzed the role of HrpB1, which was previously shown to be essential for T3S and the formation of the extracellular T3S pilus. We provide experimental evidence that HrpB1 localizes to the bacterial periplasm and binds to peptidoglycan, which is in agreement with its predicted structural similarity to the putative peptidoglycan-binding domain of the lytic transglycosylase Slt70 from Escherichia coli. Interaction studies revealed that HrpB1 forms protein complexes and binds to T3S system components, including the inner membrane protein HrcD, the secretin HrcC, the pilus protein HrpE, and the putative inner rod protein HrpB2. The analysis of deletion and point mutant derivatives of HrpB1 led to the identification of amino acid residues that contribute to the interaction of HrpB1 with itself and HrcD and/or to protein function. The finding that HrpB1 and HrpB2 colocalize to the periplasm and both interact with HrcD suggests that they are part of a periplasmic substructure of the T3S system

Betonieren unter Verkehr: Untersuchung der Auswirkungen von Erschütterungen auf jungen Beton

Im vorgestellten Beitrag wird der Einfluss von Erschütterungen auf den jungen Beton systematisch und anhand von realistischen Versuchen an Kleinkörpern aus unbewehrtem und bewehrtem Beton behandelt. Die kontrollierte dynamische Anregung erfolgt künstlich mit dem AIT-Schwingungsgenerator. Die Proben (zwei verschiedene Betonsorten: „Standard-Brückenbeton“ B3-C30/37 und „Randbalkenbeton“ B7-C25/30) werden während der Erhärtungsphase systematisch mit harmonischen als auch mit realen verkehrsinduzierten Brückenschwingungsverläufen beaufschlagt. Variiert werden Intensitäten und Frequenzgehalt sowie Signalform. Im Anschluss werden die Materialparameter bestimmt und mit ruhend gelagerten Referenzköpern verglichen. Erste Ergebnisse zeigen, dass die mechanischen Eigenschaften Druckfestigkeit und E-Modul wenig oder nur gering beeinflusst werden. Dauerhaftigkeitstests und Untersuchungen am Mikrogefüge dienen dazu, Fehler, Risse und Veränderungen im Gefüge zu identifizieren und werden im laufenden Forschungsprojekt noch weiter durchgeführt. Auswirkungen auf den Verbund zwischen Beton und Bewehrung werden durch Auszugversuche analysiert. Bei diesen Versuchen wurden bei größeren Relativbewegungen zwischen Beton und Bewehrungsstab Abnahmen der mittleren Verbundfestigkeit beobachtet. Bei geringeren Relativverschiebungen (Amplituden von ca. 0,14 mm bei Dauerverkehr) konnte die Verbundfestigkeit hingegen sogar gesteigert werden