Chapter one introduces uranium oxo chemistry with a focus on the structure, oxogroup reactivity and single electron reduction of the uranyl(VI) dication. In this context, the previous work in our group on the use of Schiff-base Pacman complexes for the reductive functionalisation of uranyl will be discussed. Chapter two details the synthesis of binuclear uranium(V) oxo complexes [(RMe2SiOUO)2(L)] (R = Me, Ph) by oxo group rearrangement and reductive silylation of uranyl(VI) silylamido precursors. The electronic structure and magnetic behaviour of the complexes are presented as well as insights into the mechanism of formation and stability. Chapter three describes the reduction and desilylation reactions of [(Me3SiOUO)2(L)]. It begins with the one- and two-electron reductions of [(Me3SiOUO)2(L)] and continues with the reactivity of the resultant mixed-valence complex K[(Me3SiOUO)2(L)]. The reactivity of the UIVUIV complex K2[(Me3SiOUO)2(L)] with water is detailed and the products, K[(OUVO)(OUIVOSiMe3)(L)] and a U12O24L6 supramolecular wheel are reported. The oxidation of K2[(Me3SiOUO)2(L)] with pyridine-N-oxide is demonstrated as a route to metalated K2[(OUO)2(L)] complexes, and the synthesis of Li2[(OUO)2(L)] and the mixed lithiated/silylated complex Li[(OUO)(OUOSiMe3)(L)] are presented as direct routes to Mx[(OUO)2(L)] complexes. Chapter four discusses the reactivity of M2[(OUO)2(L)] (M = K, Li) towards oxidation and oxo-functionalisation. The oxo- and peroxo-bridged binuclear uranyl(VI) complexes K2[(UO2)2(μ-X)(L)] (X = O2–, O2 2–) are reported from the reaction of K2[(OUO)2(L)] with different oxo-oxidising agents and the new, Group 14-functionalised oxo complexes [(ROUO)2(L)] (R = stannyl or alkyl group) are described showing similar structures, bonding and stabilities to the silylated complexes. Chapter five describes the uranyl(VI) complexes of other polypyrrolic ligands. The uranyl(VI) chemistry of the anthracenyl- and fluorenyl-substituted Pacman ligands LF and LA is demonstrated as a means of using macrocyclic control to govern the nature of the complexes formed. Uranyl(VI) complexes of the polypyrrolic, tripodal ligand H3LT are shown to form either molecular species or supramolecular gels depending on the solvent used. Chapter six concludes the work presented in this Thesis. Chapter seven outlines all experimental details.

Establishing usability specifications as measurable attributes in repeatable scenarios has been an essential task in the management and continuous improvement processes [1]. Early studies in Usability Analysis were primarily conducted to assist software developers and hardware designers in improving the Human- Computer Interface (HCI) or Man- Machine Interface (MMI). However, this study was conducted to provide comparative data supporting broad conclusions regarding the comparative merits of one technology (nonstereoscopic, conventional CAD systems) competed against another (tracked, stereoscopic virtual environments). Competing environments to establish usability features and preferences provides a new tool to the interface designer. Benchmark scenarios were designed and executed to measure navigation, fault identification/repair, and spatial awareness through a sequence of choices and to provide user preference of one GUI paradigm over another functionally similar paradigm. This study, performed on a ship design application, included an analysis of the effects of user collaboration in virtual environments.

No description available.

MSc (Eng), Faculty of Engineering and the Built Environment, University of the Witwatersrand, 2011 / Most of the remaining coalfields in South Africa are found in arid areas where process water is scarce and given the need to fully exploit all the coal reserves in the country, this presents a great challenge to the coal processing industry. Hence, the need to consider the implementation of dry coal beneficiation methods as the industry cannot continue relying on the conventional wet processing methods such as heavy medium separation. Dry coal beneficiation with an air dense-medium fluidized bed is one of the dry coal processing methods that have proved to be an efficient separation method with separation efficiencies comparable those of the wet heavy medium separation process. Although the applications of the fluidized bed dry coal separator have been done successfully on an industrial scale, the process has been characterized by relatively poor (Ecart Probable Moyen), Ep values owing to complex hydrodynamics of these systems. Hence, the main objectives of this study is to develop a sound understanding of the key process parameters which govern the kinetics of coal and shale separation in an air fluidized bed focusing on the effect of the particle size, shape and density on the performance of the fluidized separator as well as developing a simple rise/settling velocity empirical model which can be used to predict the quality of separation. As part of this study, a (40 x 40x 60) cm air fluidized bed was designed and constructed for the laboratory tests. A relatively uniform and stable average bed density of 1.64 with STDEV < 0.01 g/cm3 was achieved using a mixture of silica and magnetite as the fluidizing media. Different particle size ranges which varied from (+9.5 -16mm), (+16 -22mm), (+22 -31.5mm) and (+37 -53mm) were used for the detailed separation tests. In order to investigate the effect of the particle shape, only three different particle shapes were used namely blockish (+16 -22mm Blk), flat (+16 -22mm FB) and sharp pointed prism particles (+16 – 22mm SR).Different techniques were developed for measuring the rise and settling velocities of the particles in the bed. The Klima and Luckie partition model (1989) was used to analyze the partition data for the different particles and high R2 values ranging from (0.9210 - 0.9992) were recorded. Average Ep iii values as low as 0.05 were recorded for the separation of (+37 -53mm) and (+22 -31.5mm) particles under steady state conditions with minimum fluctuation of the cut density. On the other hand, the separation of the (+16 -22mm) and (+9.5 – 16mm) particles was characterized by relatively high average Ep values of 0.07 and 0.11 respectively. However the continuous fluctuation or shift of the cut density for the (+9.5 -16mm) made it difficult to efficiently separate the particles. Although, particle shape is a difficult parameter to control, the different separation trends that were observed for the (+16 -22mm) particles of different shapes indicate that particle shape has got a significant effect on the separation performance of the particles in the air fluidized bed. A simple empirical model which can be used to predict the rise/settling velocities or respective positions of the different particles in the air fluidized bed was developed based on the Stokes’ law. The proposed empirical model fitted the rise/settling data for the different particle size ranges very well with R2 values varying from 0.8672 to 0.9935. Validation of the empirical model indicate that the model can be used to accurately predict the rise/settling velocities or respective positions for all the other particles sizes ranges except for the (+9.5 – 16mm) particles where a relatively high average % error of (21.37%) was recorded. The (+37 -53mm) and (+22 -31.5mm) particles separated faster and more efficiently than the (+16 -22mm) and (+9.5 -16mm) particles. However, the separation efficiency of the particles can be further improved by using deeper beds (bed height > 40cm) with relatively uniform and stable bed densities. Prescreening of the coal particles into relatively narrow ranges is important in the optimization of dry coal beneficiation using an air fluidized bed since different optimum operating conditions are required for the efficient separation of the different particle size ranges and shapes. The accuracy and the practical applicability of the proposed empirical model can be further improved by carrying out some detailed rise/settling tests using more accurate and precise equipment such as the gamma camera to track the motion of the particles in the fluidized bed as well as measuring the actual bed viscosity and incorporate it in the model.

The paper aims to analyze the development of the shadow banking system in China and its role in the rapid economic growth in China for the past three decades. The shadow banking system supports small and medium sized firms and agricultural development projects. This has an important impact on poverty reduction in China as farmers largely refer to informal financial channels to get credit support for seeds, chemicals and animals. The shadow banking system offers credit supplies to lenders who cannot easily obtain credit from the official banking system. The credit supplies they offered use different financial instruments, come with higher interest rates, and were often disguised as financial products landing within the regulatory framework of the administration. The commercial banks also used the shadow banking financial instruments to meet capital thresholds from the People’s Bank of China. As a result, the shadow banking products create longer credit chains, distort credit flows in the financial system by diverting investments into short-term, high return, more risky financial markets. The turbulences in the interbank transaction market, the financial derivative market, the stock exchange markets (including the main-board, the “second tier” market for SMEs and the “third tier” market for start-ups), and the real estate market are all heavily involved in transactions conducted by the shadow banking entities. The shadow banking system in China has been expanding at a pace beyond the current regulatory structure. The internet P2P investment platforms, for instance, become popular with investors and raise funds up to RMB 1 billion each platform. There exist over thousands of internet investment portals, the most popular one being “Yu E Bao”, offered by Alibaba.com. The traditional regulatory institutions, however, do not cover shadow banking investment activities made online. Neither are insurance offered to insurance made online; as the new deposit insurance scheme only cover deposits made in the official banking system. With the ambition of boosting the internationalization of the RMB, financial deepening and economic reforms in China, the financial regulators in China face the dilemma resulting from the regulatory arbitrage associated with the expanding shadow bankinBBC system. Individual investors in China purchase the shadow banking investment products and assume their purchases come with implicit government guarantees, such as wealth management products sold by commercial banks for trust companies and local government investment platforms. On the other hand, it is critical for investors to make rational investments; thus, regulators are obliged to remind investors of risks related to the shadow banking products, that the fantasy of governments repaying failing shadow banking investments will be not realized. It is also the responsibility of the regulators to divert funds collected by the shadow banking entities to long-term investments to build up industrial bases. The financial deepening in China required the transformation of the shadow banking entities and financial products offered into ones with adequate capital cushions and sufficient liquidity. The internationalization of the RMB necessates the opening up of the capital, hence financial account in China. However, the 1997 Asian financial crisis, and the hyperinflation resulting from the dollarization in Latin America has led the Chinese regulators to be cautious in conducting currency liberalization and financial reforms. The opening up of the financial account with the liberalization of the exchange rate regime doubles the financial risks, increases the possibility of financial crises, and may result in the stagnation of economic growth. The function of the central bank as the lender of the last resort demands effective and prudential regulations for SIFIs, and also seeks to functioned to boost market confidence. At this critical turning point of the Chinese economy, defining the role of the shadow banking system, bringing them into the regulatory framework, and identifying risks created should be the priority of the financial regulators in China.

A research report submitted to the Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, in partial fulfilment of the requirements for the degree of Master of Medicine in Diagnostic Radiology Johannesburg, 2017 / INTRODUCTION: Intussusceptions may cause significant morbidity and mortality if not treated timeously. One method of conservative management is pneumatic reduction, the outcome of which is dependent on a number of factors. AIM: To determine the proportion of children with intussusception who have evidence of bowel obstruction on initial abdominal radiograph, and the failure rate of pneumatic reduction in patients with and without bowel obstruction. The study also looked into whether there were any associations between the radiological presence or absence of bowel obstruction and pneumatic reduction outcome, the finding of necrotic bowel at surgery, and CRP and WCC levels. METHOD: A retrospective study was performed using an existent paediatric surgery intussusception database. Three different readers read the baseline abdominal radiographs and subjectively determined whether bowel obstruction was present or not. Treatment choices, outcomes of the pneumatic reduction, and if available, clinical presentation and lab results were captured from the patient’s discharge summary and NHLS portal. RESULTS: A sample size of 45 patients was studied. The median age of presentation was 7 months, with 83% of the patients having had symptoms for 3 days or less. 80% of patients had bowel obstruction on initial X-ray, and of these patients, only 17% had successful pneumatic reduction. No significant association was found between bowel obstruction and the presence/absence of necrotic bowel. 64% had their symptoms documented, and only 26 % and 42 % had CRP and WCC documented respectively, which did not meet sample size requirements. CONCLUSIONS: Even though a strong association was shown between evidence of bowel obstruction and pneumatic reduction outcome, the sample study was too small to make between-group comparisons. Due to this limitation, it is recommended that further investigation be done, possibly by including patients from other South African tertiary hospitals in order to obtain statistically significant results. / MT2018

Inicialmente, é feita uma revisão bibliográfica dos principais métodos de obtenção de vanádio metálico, comparando-se os resultados obtidos com os diversos redutores empregados. Também os métodos de purificação usualmente empregados são revistos, e mostra-se a eficácia de alguns deles. A seguir, analisa-se o processo aluminotérmico de obtenção de vanádio metálico a partir de pentóxido de vanádio, compreendendo estudos termodinâmicos, cinéticos e de transporte de calor. É mostrada a influência de diversas variáveis sobre a recuperação do metal. Desenvolve-se na parte experimental o estudo sobre a aluminotermia de pentóxido de vanádio, utilizando-se para isto reatores abertos revestidos com argamassa refratária. Estuda-se a influência das variáveis de processo sobre a recuperação de vanádio, incluindo a adição de fluxantes, a granulometria dos reagentes, o tamanho da carga, a pureza dos reagentes, o uso de excesso de redutor e o modo de ignição da carga. Os resultados experimentais obtidos são apresentados e discutidos. O trabalho apresenta conclusões e sugestões para pesquisas futuras. / A literature survey on the processes of vanadium reduction was carried out having in mind the behavior of the reducing agents used. The refining methods for crude metallic vanadium were also covered in the review. The aluminothermic process for the reduction of vanadium pentoxide was particularly considered. Its thermochemistry features were studied, as well as the heat transfer and the rate phenomena concerning such a reaction system discussed. It was pointed out the effect of the processes parameters on the recovery of metallic vanadium. The experiments were designed to investigate the effects of the harge composition, the purity level of the reactants, the size of the solid particles of the reacting mixture and the ignition method on the recovery of vanadium. The aluminothermic reaction was carried out in an open reaction vessel. The experimental results are presented and discussed. The research work done has reached conclusive trends which allows the proposal for further interesting research.

Este trabalho teve por objetivo estudar a redução por hidrogênio de sínteres produzidos com coque e carvão vegetal. Para isso, foram realizadas sinterizações utilizando 3 tipos de sinter feeds hematíticos. Os sinter feeds foram caracterizados através de análise granulométrica, análise química, difração de raios-X, microscopia óptica e microscopia eletrônica de varredura. Os primeiros ensaios de sinterização visaram a produção de sínter de retorno para as sinterizações posteriores. Misturas adicionando o sinter feed resíduo do processo de pelotização de minérios (SFRP) foram sinterizadas para avaliar o efeito da adição deste subproduto no processo de sinterização. Um teste foi realizado para verificar o efeito da redução de finos presentes no sínter de retorno no processo de sinterização. Foram realizados 6 ensaios de sinterização substituindo o coque por carvão vegetal como combustível do processo. As substituições foram de 0%, 8%, 16%, 25%, 50% e 100%. As amostras com substituições de 0%, 50% e 100% foram reduzidas em termobalança, durante 6 horas, em temperatura de 1000°C, utilizando uma mistura de gases contendo Argônio 10% Hidrogênio. As amostras que apresentaram a melhor e a pior redutibilidade foram estudadas através de cálculos cinéticos, a fim de determinar os mecanismos de reação envolvidos durante a redução dos óxidos. A etapa de caracterização microscópica dos sínteres e reduzidos foi realizada de modo que tornou possível comparar a amostra de sínter antes e após o processo de redução. Os resultados mostraram que, para as misturas produzidas, o sínter fabricado com carvão vegetal diminuiu os índices de produção da sinterização e de resistência do sínter. Contudo, o sínter produzido utilizando somente carvão vegetal como combustível, apresentou maior redutibilidade. Os cálculos cinéticos indicaram, tanto para o sínter produzido com carvão vegetal quanto para o sínter produzido com coque, que o mecanismo controlador nos primeiros instantes (entre 50 e 55 minutos) é a reação química. No sínter produzido com carvão vegetal, o mecânismo muda para o controle misto. No sínter produzido com coque, o mecânismo muda para a difusão. Ensaios interrompendo o tempo de redução em 40min, 80min e 120min (40min + 40min + 40min), foram realizados com a amostra de sínter produzido com 8% de carvão vegetal. Nesta etapa, foi possível identificar os fenômenos de nucleação e crescimento da fase de ferro metálico sobre a estrutura do sínter. / This work aimed to study the sinter reduction by hydrogen produced with charcoal and coke breeze. Three kinds of hematitic sinter feeds were used. The materials were characterized by particle size analysis, chemical analysis, X-ray diffraction optical and scanning electron microscopy. The inicial sintering tests aimed to produce return fines for subsequent sintering. Mixtures adding the sinter feed residue from the pellets process were sintered to evaluate the addition effect of this product in the process of sintering. A test was conducted to verify the effect of elimination of fines present in the sinter return sintering process. Six sintering tests were conducted replacing coke breeze by charcoal as process fuel. The replacements were 0%, 8%, 16%, 25%, 50% and 100%. The samples with substitutions of 0%, 50% e 100% were reduced in thermobalance for 6 hours at a temperature of 1000°C using a blend of gases containing Argon 10% Hydrogen. The samples which presented the best and the worst reducibility were studied through kinect calculations to determine the reaction mechanisms involved during the reduction of oxide. The step of microscopic characterization of reduced sinters was carried out in a way that made possible to compare the sinter sample before and after the process of reduction. The results showed the sinter made with charcoal decrease the sinter rates of production and resistance. However, the sinter made using only charcoal as fuel presented better reducibility. The kinect calculation denotes both for the sinter made with charcoal and sinter made with coke breeze the controlling mechanism in the initial stages (between 50 and 55 minutes) is the chemical reaction. For the sinter produced with charcoal the controlling mechanism switches for mixed control. The sinter produced with coke breeze, the mechanism switches for diffusion. Tests interrupting the reduction time for 40min, 80min e 120min (40min + 40min + 40min) were produced with sinter sample produced with 8% with charcoal. At this stage it was possible to identify the phenomena of nucleation and growth phase of metallic iron on the sinter structure.

Neste trabalho realizou-se o primeiro estudo biocatalítico envolvendo reações de redução de cetonas com fungos de origem marinha. Foram utilizadas 7 cetonas comerciais como substratos e 8 fungos derivados marinhos como biocatalisadores. Os fungos foram isolados das esponjas marinhas Geodia corticostylifera (Trichoderma sp Gc1, Penicillium miczynskii Gc5, Aspergillus sydowii Gc12) e Chelonaplysylla erecta (Bionectria sp Ce5, Aspergillus sydowii Ce15, Penicillium raistrickii Ce16 e Aspergillus sydowii Ce19). A redução &alpha;-cloroacetofenona (1) foi estudada sob várias condições de reação (mudanças de pH, adição ou ausência de glicose) e o melhor resultado foi com fungo P. miczynskii Gc5, pois se obteve um rendimento isolado de 60 % e excesso enantiomérico de 50 % para a (S)-2-cloro-1-feniletanol (1a). O interessante nestes estudos foi que todos os fungos utilizados na triagem com a &alpha;-cloroacetofenona (1) apresentaram seletividade anti-Prelog. Na literatura é comum obter redução enzimática com seletividade Prelog. A &alpha;-bromoacetofenona (2) foi biotransformada pelo fungo A. sydowii Ce19 nos correspondentes compostos: (S)-2-bromo-1-feniletanol (2a), (S)-2-cloro-1-feniletanol (1a), enquanto que a &alpha;-hidroxiacetofenona (2c), &alpha;-clorocetofenona (1) e o epóxido-estireno (2b) foram obtidos por reações não enzimáticas. A p-bromo-&alpha;-bromoacetofenona (3) e a p-nitro-&alpha;-bromoacetofenona (4) foram totalmente biodegradadas pelo fungo A. sydowii Ce19. A redução biocatalítica da orto-iodoacetofenona (5) e meta-iodoacetofenona (6) com o fungo Trichoderma sp Gc1 forneceu o orto-iodo-1-feniletanol (5a) e o meta-iodo-1-feniletanol (6a) com excelentes excessos enantioméricos (e.e. > 99 %). Ficou comprovado também neste trabalho que os fungos derivados marinhos para promover as reações de redução por biocatálise precisam ser cultivados em água do mar artificial. Enquanto a p-iodoacetofenona (7) produziu o p-iodo-1-feniletanol (7a) com e.e. 48 %. / This work carried out the first biocatalytic study involving reactions of reduction of ketones with marine-derived fungi. In this study were utilized 7 commercial ketones as substrates and 8 marine-derived fungi as biocatalysts. The fungi were isolated from the marine sponges Geodia corticostylifera (Trichoderma sp Gc1, Penicillium miczynskii Gc5, Aspergillus sydowii Gc12) and Chelonaplysylla erecta (Bionectria sp Ce5, Aspergillus sydowii Ce15, Penicillium raistrickii Ce16 and Aspergillus sydowii Ce19). The reduction of 2-chloro-1-phenylethanone was studied under several conditions of reaction (changes of pH, addition or absence of glucose) and the best result was with fungus P. miczynskii Gc5, therefore it was isolated in modest yield of 60% and enantiomeric excess of 50% for the (S)-(+)-2-chloro-1-phenylethanol. The interesting in these studies was that all the fungi utilized in the screening with the 2-chloro-1- phenylethanone presented selectivity anti-Prelog. In the literature is common to obtain enzymatic reduction with Prelog selectivity. The 2-bromo-1-phenylethanone was biotransformated by the fungus A. sydowii Ce19 in the (S)-2-bromo-1-phenylethanol, (S)-2-cloro-1-phenylethanol, whereas the &alpha;-hydroxy-acetophenone, 2-chloro-1- phenylethanone and the 2-phenyloxirane were obtained by no enzymatic reactions. The 2-bromo-1-(4-bromophenyl)ethanone and the 2-bromo-1-(4-nitrophenyl)ethanone were biodegraded by the fungus A. sydowii Ce19. The biocatalytic reduction of 1-(2- iodophenyl)ethanol and 1-(3-iodophenyl)ethanol with the fungus Trichoderma sp Gc1 afforded the 1-(2-iodophenyl)ethanol and the 1-(3-iodophenyl)ethanol in excellent enantiomeric excesses (e.e. >99 %). It was verified that the marine-derived fungi must grow in artificial sea water to catalyze the reduction reactions.

Due to energy scarcity coupled with environment issues, it is likely to see the biggest shift in generation portfolio in the UK and world wide, stimulated by various governmental incentives policies for promoting renewable generation and reducing emission. The generation expansion in the future will be driven by not only peak demand growth but also emission reduction target. Thus, the traditional generation expansion planning (GEP) model has to be improved to reflect this change against the new environment. The policy makers need a better assessment tool to facilitate the new environment, so they can make appropriate policies for promoting renewable generation and emission reduction, and guide the generation mix to evolve appropriately over time. Since the expansion of new generation capacities is highly capital intensive, it makes the improvement of GEP quite urgent and important. The thesis proposes the GEP modelling improvement works from the following aspects: • Integrating short-term emission cost, unit commitment constraints in an emission target constrained GEP model. • Including the network transmission constraints and generation location optimization in an emission constrained GEP. • Investigating the impacts of multi-stage emission targets setting on an emission constrained GEP problem and its overall expansion cost. • Incorporating the uncertain renewable generation expansion and short-term DSR into the GEP problem and find out its potential contributions to the GEP problem. A real case study is made to determine the optimal generation mix of the Great Britain in 2020 in order to meet the 2020 emission reduction target. Different optimal generation mixes of the UK in 2020 are identified under a series of scenarios. The scenarios are constructed according to different GB network transmission capacity hypotheses and demand side response (DSR) level scenarios.