Recent advances in exploring physiology and biodiversity of ectomycorrhizas highlight the functioning of these symbioses in ecosystems

Ectomycorrhizas, the dominating mycorrhizal symbiosis in boreal, temperate and some tropical forests, are formed by 5000-6000 species of the asco- and basidiomycetes. This high diversity of fungal partners allows optimal foraging and mobilisation of various nitrogen and phosphorus forms from organic soil layers. In this review, two approaches to study the functioning of this multitude of symbiotic associations are presented. On selected culture models, physiological and molecular investigations have shown that the supply of hexoses has a key function in controlling the plant^fungus interaction via partner-specific regulation of gene expression. Environmental factors which affect fungal carbon supply, such as increased nitrogen availability, also affect mycorrhiza formation. Based on such laboratory results, the adaptative capability of ectomycorrhizas to changing field conditions is discussed. The second approach consists of analysing the distribution of mycorrhizas in ecosystem compartments and to relate distribution patterns to variations of ecological factors. Recent advances in identification of fungal partners in ectomycorrhizas by analysing the internal transcribed spacer of ribosomal DNA are presented, which can help to resolve sampling problems in field studies. The limits of the laboratory and the field approaches are discussed. Despite some problems, this combined approach is the most promising. Direct investigation of gene expression, which has been introduced for soil bacteria, will be difficult in the case of mycorrhizal fungi which constitute organisms with functionally varying structure

Photochemisch strukturierte computergenerierte Hologramme in Bakteriorhodopsin-Schichten

Ziel dieser Dissertation ist die Untersuchung des photochemischen Aufzeichungsprozesses von computergenerierte Hologrammen (CGH's) innerhalb des Biomaterials Bakteriorhodopsin (BR). Dabei werden folgende Schwerpunkte detailliert analysiert: - Implementierung und Untersuchung verschiedene Algorithmen zur Berechnung von CGH's. Die Algorithmen sind insbesondere hinsichtlich der Verwendung des Biomaterials BR als Hologrammedien zu beurteilen. - Untersuchung des Aufzeichungsprozesses von CGH's mittels eines direkten Laserschreibsystems. Bei den CGH-Herstellungsverfahren werden die physikalischen und biochemischen Eigenschaften von BR gezielt ausgenutzt, um die für die CGH-Aufzeichnung optimale Oberflächenprofilierung und/oder Brechungsindexmodulation zu erreichen

Import options for chemical energy carriers from renewable sources to Germany

Import and export of fossil energy carriers are cornerstones of energy systems world-wide. If energy systems are to become climate neutral and sustainable, fossil carriers need to be substituted with carbon neutral alternatives or electrified if possible. We investigate synthetic chemical energy carriers, H2, CH4, MeOH, NH3 and Fischer-Tropsch fuels (FTF), produced using electricity from RES as fossil substitutes. [...] We model the sourcing of feedstock chemicals, synthesis and transport along nine different Energy Supply Chains to Germany (DE) and compare import options for seven locations around the world against each other and with domestically sourced alternatives on the basis of their respective cost per unit of H2 and energy delivered. We find that for each type of chemical energy carrier, there is an import option with lower costs compared to domestic production in DE. No single exporting country or energy carrier has a unique cost advantage, since for each energy carrier and country there are cost-competitive alternatives. This allows exporter and infrastructure decisions to be made based on other criteria than energy and cost. The lowest cost means for importing of energy and H2 are by H2 pipeline from Denmark, Spain and Western Asia and Northern Africa starting at 36 EUR/MWh$_{LHV}$ to 42 EUR/MWh$_{LHV}$ or 1.0 EUR/kg$_{H2}$ to 1.3 EUR/kg$_{H2}$ (in 2050, assuming 5 % p.a. capital cost). For complex energy carriers derived from H2 like CH4, NH3, MeOH or FTF, imports from Argentina by ship to DE are lower cost than closer exporters in the European Union or Western Asia and Northern Africa. For meeting H2 demand, direct H2 imports are more attractive than indirect routes using CH4, MeOH or NH3 imports and subsequent decomposition to H2 because of high capital investment costs and energetic losses. We make our model and data available under open licenses for adaptation and reuse

Two-Photon-Absorption Triggered Release of 5-Fluorouracil from Isomer-Pure Polymer Bound Syn-Head-to-Head Dimers for Novel Intraocular Lenses

Different stereoisomers of the cytotoxic 5-fluorouracil (5FU) homodimers were synthesized by photochemical [2+2]-cycloaddition and polymerized into MMA/HEMA to form a novel drug-loaded copolymer for intraocular lenses as irradiation-activated treatment for secondary cataract. Three isomers were obtained, and showed significant differences in cleavage efficiency on photo-cleavage via single-photon-absorption (SPA) and two-photon-absorption (TPA). The most efficient TPA cleavage rate was observed for the syn-head-to-head 5FU dimer, which was, consequently, used for drug loading of the polymeric material to obtain a drug-loaded material of higher efficiency compared to previous works. The light and thermal stability of the polymer were confirmed and multi-dose release of the drug in aqueous solution for possible repeated treatment of cataract was proven

Import options for chemical energy carriers from renewable sources to Germany

Import and export of fossil energy carriers are cornerstones of energy systems world-wide. If energy systems are to become climate neutral and sustainable, fossil carriers need to be substituted with carbon neutral alternatives or electrified if possible. We investigate synthetic chemical energy carriers, hydrogen, methane, methanol, ammonia and Fischer-Tropsch fuels, produced using electricity from renewable energy sourceses as fossil substitutes. Renewable energy sourceses potentials are obtained from GIS-analysis and hourly resolved time-series are derived using reanalysis weather data. We model the sourcing of feedstock chemicals, synthesis and transport along nine different energy supply chains to Germany. and compare import options for seven locations around the world against each other and with domestically sourced alternatives on the basis of their respective cost per unit of hydrogen and energy delivered. We find that for each type of chemical energy carrier an import option with lower costs compared to domestic production in Germany exists. The lowest cost import options for energy and hydrogen are by hydrogen pipeline from Denmark, Spain and Western Asia and North Africa at 40.6 to 46.8 EUR per MWh (LHV) (1.4 to 1.6 EUR per kg H2) in 2050 assuming 5% p.a. capital cost. For complex energy carriers like methane, ammonia, methanol or Fischer-Tropsch fuel, imports from Argentina by ship to Germany are attractive even compared to closer European Union or Western Asia and North Africa exporters. For meeting hydrogen demand, direct hydrogen imports are more attractive than indirect routes using methane, methanol or ammoniaimports and subsequent decomposition to hydrogen because of high capital investment costs and energetic losses of the indirect routes. We make our model and data available under open licenses for adaptation and reuse

Energy-filtered transmission electron microscopy of biological samples on highly transparent carbon nanomembranes

Ultrathin carbon nanomembranes (CNM) comprising crosslinked biphenyl precursors have been tested as support films for energy-filtered transmission electron microscopy (EFTEM) of biological specimens. Due to their high transparency CNM are ideal substrates for electron energy loss spectroscopy (EELS) and electron spectroscopic imaging (ESI) of stained and unstained biological samples. Virtually background-free elemental maps of tobacco mosaic virus (TMV) and ferritin have been obtained from samples supported by ~ 1 nm thin CNM. Furthermore, we have tested conductive carbon nanomembranes (cCNM) comprising nanocrystalline graphene, obtained by thermal treatment of CNM, as supports for cryoEM of ice-embedded biological samples. We imaged ice-embedded TMV on cCNM and compared the results with images of ice-embedded TMV on conventional carbon film (CC), thus analyzing the gain in contrast for TMV on cCNM in a quantitative manner. In addition we have developed a method for the preparation of vitrified specimens, suspended over the holes of a conventional holey carbon film, while backed by ultrathin cCNM

Schutz von Holz- und TMP-Holzstoff-Oberflächen vor lichtinduzierter Vergilbung durch chemische Modifikation des Lignins

Ein neuer Reaktionsmechanismus der Chromophorenbildung im Lignin wurde bei der lichtinduzierten Vergilbung von Holz- und TMP-Holzstoff-Oberflächen identifiziert. Die Photolabilität der acetylierten Oberflächen wurde anhand von Untersuchungen mit Ligninmodellsubstanzen nachgewiesen. Basierend auf dieser Erkenntnis wurde eine neuartige Schutzmethode für Holz- und TMP-Holzstoff-Oberflächen vor lichtinduzierter Vergilbung entwickelt

Kooperationsformen im informationstechnischen Bereich im wissenschaftlichen und öffentlichen Bibliothekswesen in Baden-Württemberg

Die Bibliotheken können das sich ständig erweiternde Dienstleistungsspektrum nur umfassend abdecken, wenn sie moderne Bibliotheksinformationssysteme zur Automatisierung und Rationalisierung betriebsinterner Arbeitsabläufe einsetzen. Da der Einstieg oder Umstieg auf ein solches, zumeist integriertes Bibliothekssystem, in der Regel detaillierte EDV-Kenntnisse voraussetzt, gehen immer mehr Bibliotheken dazu über, die Umstellung nicht autonom, sondern in Kooperation mit einer zentralen EDV-Koordinierungs- stelle durchzuführen. In der vorliegenden Arbeit wird diese Entwicklung am Beispiel von zwei EDV-Kooperationsformen aus dem wissenschaftlichen und öffentlichen Bibliothekswesen in Baden-Württemberg aufgezeigt. Im Bereich des wissenschaftlichen Bibliothekswesens wird dabei die Einführung von HORIZON als Verbund- und Lokalsystem unter besonderer Berücksichtigung der Aufgaben des Bibliotheksservice-Zentrum Baden- Württemberg (BSZ) dargestellt. Im Bereich des öffentlichen Bibliothekswesens in Baden-Württemberg wird die Zusammenarbeit der Rechenzentren mit den öffentlichen Bibliotheken genauer beschrieben. Besondere Beachtung findet hierbei das Rechenzentrum Alb-Schwarzwald in Reutlingen, das derzeit auf ein neues Betreuungsverfahren umstellt. Die Herausarbeitung und das Aufzeigen der wesentlichen Unterschiede und Gemeinsamkeiten dieser beiden EDV-Kooperationsformen bilden den Abschluß der Arbeit