Poröse Koordinationspolymere mit Linkern auf Basis Polycyclischer Aromatischer Kohlenwasserstoffe: Ein aromatisches Leipziger Allerlei

Zusammenfassung In der vorliegenden Promotionsschrift werden Strategien zur Erzeugung von Linkermolekülen beschrieben, die geeignet sind, um als Bauelemente für sogenannte \"Metal-Organic rameworks\" (MOF) eingesetzt zu werden. Diese Stoffe bestehen aus einem organischen \"Linker\"-Teil, welcher die Metalleinheiten (\"Sekundäre Baueinheit\", SBU) miteinander verbindet, und dadurch die Entstehung von dreidimensionalen porösen Netzwerken ermöglicht. Dieses Projekt wurde an der Universität Leipzig in der Arbeitsgruppe von Prof. Dr. rer. nat. Dr. h.c. Evamarie Hey-Hawkins am Institut für Anorganische Chemie durchgeführt. Seit den frühen neunziger Jahren genießen MOFs großes Interesse aufgrund ihrer besonderen Eigenschaften als Festkörper mit wohldefinierter und permanenter Porosität. In der Einleitung dieser Promotionsschrift werden das Anwendungspotential oder bereits existierende Anwendungen für MOFs und verwandte poröse Feststoffe näher beschrieben. Mögliche Anwendungsgebiete sind unter anderem Gasspeicherung, Trennverfahren, zur Katalyse, in der Medizin und für Detektoren in der analytischen Chemie. Die Auswahl der organischen Baueinheiten für die Synthese von MOFs richtet sich nach Kriterien wie z.B. thermischer Stabilität, Geometrie der koordinierenden Einheiten, Rigidität des Linkermoleküls. Weiterhin können potentielle sekundäre Effekte berücksichtigt werden, z.B. Eignung für katalytische Prozesse, Ladungspufferung oder Lichtsammelvermögen. Alle Linker enthalten aromatische Einheiten; es werden Anthracen, Binaphthyl (verkörpert durch chirale BINAPO-Einheiten), Biphenyl, Pyren und Perylen als Mittelstück des Linkers eingesetzt. Die Promotionsschrift beleuchtet auch in einem Streifblick die Geschichte, das Vorkommen, mögliche Anwendungen und Giftigkeit von Molekülen mit polycyclischen aromatischen Kohlenwasserstoffgruppen. Die Synthese der Linker wurde mittels der folgenden Route realisiert: Bromierung der aromatischen Bestandteile und Anfügen von Endstücken (\"capper\") - welche die koordinierenden Einheiten enthalten - durch die Suzuki-Miyaura-Kupplung. Die Syntheserouten für den bromierten aromatischen Mittelteil des Linkers, die Boronsäuren und die vollständigen Linker, werden im experimentellen Teil beschrieben, und die erhaltenen Linker werden charakterisiert. Für den anorganischen Teil des MOF wurden außerdem ausgewählte komplexe Einheiten erzeugt, die als Startmaterialien für den sogenannten \"controlled SBU approach\" (CSA) dienen. Bei dieser Methode wird eine Baueinheit erzeugt, die der gewünschten eigentlichen Baueinheit im fertiggestellten MOF ähnlich ist und dann als Präkursor in der Synthese eingesetzt wird. Verschiedene Ansätze zur Erzeugung von MOFs wurden ausgeführt: Langsame Diffusion in Flüssigkeiten oder Gelen und vor allem Tempern der organischen und anorganischen Baueinheiten oder Startmaterialien in einem Lösungsmittel, teilweise unter solvothermalen Bedingungen. Mehrere Polymere wurden in einer zur Röntgenstrukturbestimmung geeigneten kristallinen Form erhalten. Die Strukturen werden in der vorliegenden Arbeit präsentiert und diskutiert. Ein Ausblick auf weiterführende Untersuchungen an diesen Verbindungen wird ebenfalls gegeben.:(s. PDF ab S. 9 (PDF-Seite)) 1 Vorwort S. 1 2 Polycyclische aromatische Kohlenwasserstoffe S. 2 3 Poröse Festkörpermaterialien S. 20 4 Auswahl / Design der Linkermoleküle S. 50 5 Experimenteller Teil S. 65 6 Diskussion der Ergebnisse S. 194 7 Danksagung S. 293 8 Literaturverzeichnis S. 299 9 Anhang (X-Ray, NMR, DTA-TG, UV-Vis) S. 328Abstract This thesis describes approaches to obtain linker molecules that are suitable to build a so-called \"metal-organic framework\", MOF (or porous coordination polymer, PCP). These materials consist of an organic linker part that connects the metal units, \"secondary building units\" (SBU), with each other to form threedimensional, hollow networks. This project was performed at the University of Leipzig in the multinational workgroup of Prof. Dr. rer. nat. Dr. h.c. Evamarie Hey-Hawkins, at the Faculty for Inorganic Chemistry. These MOF materials have gained a lot of interest since the early 1990s for their special properties as solid materials with a well-defined, permanent porosity. The introductory part of this thesis elaborates potential or already current usage of MOF materials and related porous solids, such as gas storage, separation processes, catalysis, medical use and use in analytic detection. The choice of organic building blocks for the synthesis of MOFs followed certain criteria, such as thermal stability, geometry of coordinating units, rigidity of the linker molecule, and potential secondary effects such as suitability for catalytic purposes, charge buffering or light harvesting. All linkers feature aromatic units, and among the cores are moieties like anthracene, binaphthyl (represented by the chiral BINAP), biphenyl, pyrene and perylene. A glance is thrown on the history, occurrence, possible use and potential toxicity of molecules with polycyclic aromatic hydrocarbon moieties. Synthesis of the linkers is implemented by use of brominations of the aromatic core units and attaching capper units - carrying the coordinating units - by means of Suzuki-Miyaura-coupling. The synthesis routes to these molecules, brominated aromatic core, boronic acids and finished linkers, are described in the experimental part. The obtained linkers are characterised and described. Furthermore, selected complex units for the inorganic part of a potential MOF were created as starting materials for a so-called \"controlled SBU approach\" (CSA); wherein a building block, very similar to the desired unit in the final framework, is prepared and then used as a precursor in the synthesis. Various attempts at the generation of MOFs were conducted: Slow diffusion in liquids or gels, and, especially, reactions by tempering the organic and inorganic building blocks or starting materials in a solvent - partially also under solvothermal conditions. Several polymers were obtained in crystalline form, suitable for structure determination by X-ray crystallography. These structures are presented and discussed in this work, as well as the further research on these solids and the results being achieved.:(s. PDF ab S. 9 (PDF-Seite)) 1 Vorwort S. 1 2 Polycyclische aromatische Kohlenwasserstoffe S. 2 3 Poröse Festkörpermaterialien S. 20 4 Auswahl / Design der Linkermoleküle S. 50 5 Experimenteller Teil S. 65 6 Diskussion der Ergebnisse S. 194 7 Danksagung S. 293 8 Literaturverzeichnis S. 299 9 Anhang (X-Ray, NMR, DTA-TG, UV-Vis) S. 32

Development and application of decision support systems for improved planning and operation of large dams along the White Nile.

Doctor of Philosophy in Agricultural Engineering. University of KwaZulu-Natal, Pietermaritzburg 2015.In this study the regulation of Lakes Victoria, Kyoga and Albert in East Africa are investigated with the objective of maximising hydropower production subject to system constraints for existing and future planned dams along the Upper White Nile in Uganda. A Decision Support System (DSS) has been assembled and applied to search for efficient lake-reservoir operating rules for this basin. Elements of the DSS include power plant functions, a simulation model of the Upper Nile Equatorial Lake Basin, the Stochastic Analysis Modelling and Simulation (SAMS) computer software package for analysing hydrologic time series and the Colorado State University Dynamic Programming (CSUDP) model for solution of the optimisation problem. A concurrent record of observed lake levels and outflows for the three lakes during the reference period 1899 – 2008 has been constructed from various long term monitoring stations and utilised to derive net basin supply or net inflow time series at a monthly and annual time scale. Statistical tests confirmed the non-stationarity of the annual lake net basin supply time series. A justification to model the stochastic process of the monthly inflows as a Markov process was also reached. A Univariate Shifting Mean model was fitted to the annual historical data in tandem with a model for temporal disaggregation of annual to monthly net basin supplies for the purposes of generating synthetic flow series. The model performed well in terms of preserving the statistical characteristics of the historical reference set for each lake. The synthetic time series are considered to be a useful reference data set for future research in generating reservoir operating rules. Two Dynamic Programming (DP) models that may be used to generate reservoir operating rules were investigated. The desired scope of optimization was however curtailed by the well-known dimensionality problem of DP. Application of the deterministic method of Incremental Dynamic Programming (IDP) to the optimisation problem could only be carried out on a monthly time step and for single years separately. Annual time step optimization could only be carried out for the historic net inflows. The 1000 stochastically generated time series of net basin supplies could not be utilized within the implicit framework of deriving operating rules due to impractical computational requirements. The IDP however, yielded a realistic set of optimal operating policies at an annual time scale for the historical reference period (1898 – 2008). The beginning of year lake levels and annual release magnitudes obtained were compared against similar data for natural unregulated lake conditions. It is concluded that, in general, lake regulation would yield desirable benefits in terms of hydropower generation but would lead to marked deviation from natural lake levels and more variable outflows. The Stochastic Dynamic Programing (SDP) model was only applied to Lake Victoria in single reservoir optimization scheme due to limitations imposed by the large dimensionality of the problem and difficulty of simultaneously incorporating multiple lake reservoir transition probability matrices in the model. Application of the model for Lake Victoria showed that, it was feasible to define final storage levels for discretized initial storage and previous period inflow class combinations. The results from the study indicate that realistic heuristic operation rules can be inferred from the results of applying the IDP models and SDP algorithm

Networks and coalitions in the implementation of the International Treaty on Plant Genetic Resources for Food and Agriculture in Uganda

Uganda acceded to the International Treaty for Plant Genetic Resources for Food and Agriculture (ITPGTFA) in the year 2003. Despite this, there are still gaps in implementation of the treaty in the country. The article provides insights into the systemic interactions and coalitions among actors in the implementation of the treaty and subsequent barriers to the implementation of the ITPGRFA. Using social network analysis, the interactions of 26 key policy actors are mapped for 4 main expertise networks that are important for implementation of the treaty; that is, the policy direction networks; scientific expertise; financial expertise; and legal networks in order to identify gaps for further action. Findings indicate that the linkages between actors are poor especially in the legal expertise and policy direction networks where the competent authority for the treaty does not have efficient connections with critical and non-critical actors. Many key actors are also excluded from the network leading poor information and resource flows among stakeholders implementing the treaty. In the interim, a memorandum of understanding has been signed by three major institutions that are key to establish clear processes for implementation of the treaty and establishing clear guidelines for access and benefit sharing and clear roles of institutions involved in the policy development and implementation. Key lessons learned from this research are that networks and coalitions are important for fostering information and exchange of expertise to enable effective implementation or domestication of the international treaty (IT). The structured engagement of other non-governmental stakeholders such as non-governmental organisations (NGOs) and international organizations that provide financial and technical support for various aspects of policy implementation is also important

Reducing climate-induced heat stress in pigs in Uganda: Policy actions

Pig farming is important for income generation and nutrition for a large population in Uganda, with 4.2 million pigs being kept in 2017. However, future projections indicate that domestic pork production will not be sufficient to meet the increasing demand. This situation is likely to be aggravated by climate-induced heat stress. Analysis of mhistorical climate data and simulation of future periods predicts a gradual shift towards more severe heat stress conditions experienced in most parts of the country. Animals experience heat stress when subjected to a series of conditions where the animal’s body is overheating. Pigs are more vulnerable to heat stress because they do not have functioning sweat glands. Heat stress distorts the pigs’ feed intake, growth and reproduction and makes pigs vulnerable to diseases. This, in turn, brings economic losses. In Uganda, smallholder pig production systems -which are the majority- are transitioning towards market-oriented models. However, to remain sustainable, adaptation of these systems to heat stress should be a priority. This policy brief synthesizes research findings on heat stress in pigs in Uganda, reviews proven interventions elsewhere, and concludes with evidence-based policy recommendations. Recommended policy options include prioritization of coordinated national & local level policy making and implementation, promoting heat stress coping and adaptation measures at farm level, action plans at various value chain stages, close research-policy cooperation and information sharing, and action and investment by donors and development organizations. If agricultural extension, policymakers and planners, and development donors and organizations leverage these options, pig farmers will be able to cope, adapt and mitigate heat stress in pigs and the pig production sector in Uganda will become more resilient

Determining Factors that Influence Household Food Insecurity in Uganda: A Case Study of Tororo and Busia Districts

Addressing the national food insecurity problem requires an understanding and measurement of food insecurity at micro-level using a wide range of explanatory variables. Measurement of food insecurity is a challenge because it is a multi-faceted latent and continuous phenomenon explained by many variables. This paper examines these variables and applies exploratory factor analysis to identify variables which significantly influence household food insecurity and how they uniquely associate with specific food insecurity factors. Primary data on food availability, access, utilization and coping strategies were collected from 1175 randomly selected rural households in Tororo and Busia Districts of Uganda. Feasibility of exploratory factor analysis was analyzed using Pearso