De Novo synthesis of arenes and heteroarenes

This Ph.D. thesis describes the synthesis of polysubstituted arenes and heteroarenes from nonaromatic precursors via a ring-opening aromatization reaction of bicyclo[3.1.0]hexan-2-ones

River infrastructure planning decision support tool

A decision support tool has been developed to optimise environmental and socioeconomic trade-offs associated with river infrastructure (i.e. barriers), including river connectivity, hydropower generation, and shipping and other costs. The model extends previous work by considering (i) multithreaded river sections, essential for estimating river connectivity in the presence of diverted channels for hydropower and shipping, (ii) backwater effects caused by the lowering or raising of artificial in-stream structures, which , in turn, affect hydropower generation potential and transport capacity of shipping vessels, and (iii) the integration of realistic cost functions for estimating the cost of hydropower installation/retrofitting and cross-port shipping of goods by a heterogeneous fleet of vessels. To demonstrate the applicability of the planning tool, a database for the Neckar River in Germany was created. The database contains more than 1000 existing river barriers and more than 4,000km of river and includes detailed information on river flow, hydropower, and waterborne traffic. The planning tool is designed to find the best combination of river infrastructure modification, mitigation, and removal actions in order to optimise three key performance indicators (KPIs): 1) river connectivity based on a generalisation of the well-known Dendritic Connectivity Index, 2) hydropower potential/revenue and 3) total cost, broken down by the cost of structural engineering works, installation and retrofitting of hydropower, and annual shipping. The model focuses specifically on the socioeconomic benefits of hydropower and shipping, as these are the two main human uses of rivers within the Neckar catchment. The model could be readily modified to consider other environmental and socioeconomic factors, which may be important in other planning areas, such as irrigation, water supply, fishing, recreation, and water purification. The planning model has been specially configured to examine ten scenarios for adaptive barrier management. The results show which river infrastructure modification, mitigation, and removal actions could be undertaken to maximise connectivity, maximise hydropower, or minimise total cost subject to defined river connectivity and energy production targets

Determination of nutrient salts by automatic methods both in seawater and brackish water: the phosphate blank

9 páginas, 2 tablas, 2 figurasThe main inconvenience in determining nutrients in seawater by automatic methods is simply solved: the preparation of a suitable blank which corrects the effect of the refractive index change on the recorded signal. Two procedures are proposed, one physical (a simple equation to estimate the effect) and the other chemical (removal of the dissolved phosphorus with ferric hydroxide).Support for this work came from CICYT (MAR88-0245 project) and Conselleria de Pesca de la Xunta de GaliciaPeer reviewe

Untersuchung von Maßnahmen zur Wärmeübergangserhöhung an einem Reaktor für eine Metallhydrid-Kältemaschine

Vor dem Hintergrund eines neuen Klimatisierungskonzepts für mobile Brennstoffzellenanwendungen wird ein Metallhydridreaktor untersucht. Der Reaktor, der als Kernkomponente einer Kältemaschine vorgesehen ist, wird hinsichtlich seines äußeren Wärmeübergangs evaluiert und optimiert, um die Leistungsdichte des Gesamtsystems zu erhöhen. Mehrere Konzepte zur Wärmeübergangserhöhung im Ringspalt um den Reaktor werden mit Korrelationen aus der Literatur bewertet. Die Variation des hydraulischen Durchmessers und das Einbringen einer Drallströmung werden über Experimente zur Reaktordynamik und mit Simulationsmodellen weiter untersucht. Eine Reduktion des hydraulischen Durchmessers und die Erhöhung der Durchflussrate des Wärmeträgerfluids steigerten die desorbierte Wasserstoffmenge in einem Kühlzyklus. Die Drallströmung lieferte hier hingegen keine Steigerung im Vergleich zum unveränderten Ringspalt. Zwei Simulationsmodelle mit unterschiedlicher Implementierung des Wärmeübergangs und Fluidstroms wurden definiert und beschreiben das Verhalten der Reaktorkonstruktion. Die Ergebnisse bestätigen eine Erhöhung der desorbierten Wasserstoffbeladung bei Steigerung des Wärmeübergangs. Mit Hilfe von simulierten Parameterstudien werden verschiedene Konfigurationen und Betriebspunkte beurteilt und ein ideales Auslegungs- und Betriebsfenster vorgeschlagen

De Novo Synthesis of Benzannelated Heterocycles

Benzannelated heterocycles such as indoles and indazoles are prominent structural motifs found in natural products, pharmaceuticals and agrochemicals. For their synthesis, chemists traditionally either functionalize commercially available heterocycles or resort to transformations that make use of benzenederived building blocks. Here, we report a powerful cascade reaction that enables the de novo construction of variously substituted indoles, indazoles, benzofurans and benzothiophenes from readily available bicyclo[3.1.0]hexan2ones. The transformation can be conducted under mild, nonanhydrous conditions. For the synthesis of indoles, mechanistic studies revealed that the electrocyclic ringopening of the bicyclic ringsystem and aromatization precedes the 3,3sigmatropic rearrangement.(VLID)4045878Accepted versio