Thesis (MSc. (Chemistry)) -- University of Limpopo, 2021 / Surface water from the rivers serves as a source of water for many purposes including drinking, irrigation and animal farming. The quality of surface water deteriorates due to human, animals and industrial waste. Amongst these wastes, selenium and other trace elements contaminants are included. Selenium can either be essential or toxic depending on the concentration and oxidation state. The aim of this current study was to determine the concentrations of inorganic selenium [Se(IV) and Se(VI)] in water and sediment samples collected from Blood and Mokolo Rivers in Limpopo Province, South Africa. Water and sediment samples were collected from 10 different sampling sites from down to upstream of each river. Water samples were acidified with 1% ultra-pure HNO3 and analysed directly for total selenium concentration. The accuracy of the method was validated using SRM1643f (trace elements in water reference material). Sediment samples were digested using microwave assisted acid digestion for the determination of total concentration of selenium. The accuracy of the method was evaluated using SRM 8704 (sediment standard reference material). Total concentration of selenium in both water and sediment samples were quantified using ICP-MS. The total concentration of selenium in water samples from Blood and Mokolo River were found to be in the range of 0.0682 to 2.72 μg/L and 0.0851 to 25.4 μg/L respectively. The selenium concentrations in all sediment samples were found to be below instrument detection limit of 0.0571 ng/g in both rivers. An adopted SPE method using Dowex 1 x 2 resin (chloride form) as an adsorbent material to preconcentrate and separate Se(IV) and Se(VI) was used for the speciation in water samples. Both Se(IV) and Se(VI) were retained on the column. The retained Se(IV) and Se(VI) were eluted using 15 mL 1 M HNO3 and 3 M HNO3 respectively at a flow rate of 2 ml/min and diluted to the final volume of 20 mL. The instrument detection limit was 0.192 μg/L and 0.108 μg/L for Se(IV) and Se(VI) respectively. The validation of the method was performed by using SRM 1643f and solutions of known concentrations. The water samples were adjusted to an optimum pH of 6 throughout the speciation analysis. The Se(IV) had higher percentage recoveries of 95 – 114% than Se(VI) with 53%. vi Concentrations of Se(IV) and Se(VI) in Blood River ranged from 0.0411 to 0.820 μg/L and 0.0811 to 1.75 μg/L respectively. Concentrations of Se(IV) and Se(VI) in Mokolo River ranged from 0.135 to 2.79 μg/L and 0.0961 to 14.8 μg/L respectively. The inorganic selenium species in water samples were also determined by using the adopted online mode of HPLC-ICP-MS with Hamilton PRP-X100 column. The separation of the two species was achieved by using isocratic elution of 100 mM NH4NO3 at pH 8.5 in 8 min. The method was successfully validated using SRM 1643f. The LOD of 0.842 μg/L and LOQ of 2.81 μg/L for Se(IV) were achieved. The LOD of 0.690 μg/L and LOQ of 2.30 μg/L for Se(VI) were achieved. The Se(IV) and Se(VI) concentrations determined using HPLC-ICP-MS were found to be in good agreement with Se(IV) and Se(VI) concentrations obtained using SPE in both rivers. The presence of Se(IV) and Se(VI) in water samples in Blood and Mokolo Rivers indicates that industrial and agricultural activities taking place near the rivers have an effect on the quality of the water. The selenium in water may be due to wastes from industrial, municipal and agricultural runoffs. The absence of selenium in sediment samples suggests that the area where the rivers are located is not rich in selenium.

The goal of this thesis is to explore the possibility on if it is possible to automate regression testing for a SaaS application with a serverless approach. The thesis covers the fundamentals of the software development lifecycle, cloud concepts, different types of testing frameworks, and SaaS applications. The report researches various testing tools that can be used in accordance with Polestar’s needs. The testing framework must run the existing tests and deliver the results of the tests. The system must be able to coexist with the testing strategy that is in place today. The result is a testing framework that can run a number of selected tests on the SaaS application Salesforce. The system was deployed with serverless docker containers through Amazon Web Services. The report also covers what a future implementation can look like and potential improvements. / Målet med denna avhandling är att undersöka om det går att automatisera regression testning för en SaaS-applikation med hjälp av ett serverlöst tillvägagångsätt. Avhandlingen täcker grunderna inom molnkoncept, mjukvaruutveckling, olika typer av testramverk och SaaS-applikationer. Avhandlingen går även igenom gamla arbeten som har gjorts inom området. Rapporten behandlar val av verktyg med åtanke på vad företaget Polestar har för    behov. Testramverket ska kunna utföra automatiska regressionstester på SaaS-applikationen Salesforce. Resultatet är ett testramverk som kan köra ett antal utvalda tester på Salesforce. Systemet driftsattes med hjälp av serverlösa Docker containrar på Amazon Web Services. Avhandlingen täcker även alternativa verktyg som kan användas för testautomation och även potentiella förbättringsmöjligheter.

This diploma thesis is focused on introduction of advanced possibilities of working with testing Selenium WebDriver framework. Basics of software testing and Selenium framework are described in first part of the text. Second chapter contains overview of available tools and applications which enhance Selenium WebDriver. These include frameworks using WebDriver API, software containers, automatization tools, continuous integration tools and services which enable to run tests remotely. Last chapter contains case study which describes implementation of automated testing in BellaDati company. The attachment contains user guide for Geb framework which was used in the case study.

The aim of this project is to develop a component able to retrieve taxi providers in Sweden, based on input of coordinates and a search radius. The result should be available in a well-structured and accessible way through an RESTful web service. The study is conducted based on a customer inquiry stating that the component should be built using open-source tools and be developed in such a way that allows the component, or parts of the component, to be integrated in a larger system. Therefore, a preliminary study was conducted in order to find suitable open-source tools that are able to solve the specific customer requirements. The component uses an ad hoc company search engine to retrieve the taxi providers, contact information and coordinates. Additional information needed for determining the correctness of the taxi providers are retrieved from external resources and a filtering process is then performed before they are saved in persistent store. The project is successful in solving the main purpose and most of the customer requirements, while the RESTful service is unable too fully meet the requirement stating that the component should be able to handle multiple concurrent clients while still maintain responsiveness. This, is mainly due to the decision not to use an ad hoc framework in handling geospatial data structures and calculations and was a trade-off to ensure re-usability and integration of the component in a larger system. / Avsikten med denna studie är att bygga en komponent som kan returnera taxiföretag i Sverige baserat på koordinater och en sökradie. Resultatet skall presenteras för användare eller andra tjänster på ett välstrukturerat och tillgängligt sätt via en RESTbaserat webbtjänst. Projektet är ett resultat av en kundförfrågan i vilken det även specificeras att komponenten skall använda sig av data eller verktyg som är fritt tillgängliga och att den skall vara byggd på ett sådant sätt att det går att använda hela, eller delar av, komponenten i ett större system. En kortare förstudie genomfördes med syfte att hitta lämpliga verktyg som bygger på öppen källkod för att lösa de specifika krav kunden ställt på komponenten. Komponenten använder sig av en sökmotor för företag-sök där resultaten görs tillgängliga via ett RESTbaserat API. Varje företag genomgår sedan en filtreringsprocess innan de sparas i databas för att avgöra om det uppfyller de kriterier som är uppsatta. Denna filtrering baseras på information som inhämtats genom en automatiserad process. Denna studie har varit framgångsrik i avseendet att bygga en komponent som kan returnera företag inom ett visst område baserat på koordinater och en given sökradie. Den uppfyller även de allra flesta av de krav kunden har satt upp, med undantag för det krav som efterfrågar en responsiv hantering av många samtidiga användare. Detta beror främst på valet att inte använda sig av ett ramverk avsett för hantering av geospatial data. Detta var en avvägning som gjordes för att försäkra sig om att komponenten skulle vara återanvändbar i ett större system.

Previously, selenium was known as an element with negative properties. However, in the last century, the significant positive effects on human health were detected. Currently, the function, behavior and toxicity of selenium are still not well known. The key to understand it is to do speciation analysis. The aim of this diploma thesis is to develop method for determination inorganic (sodium selenite and selenate) and organic (selenourea, selenocystine, selenomethionine) selenium compounds. Parameters of apparatus for electrochemical hydride generation with atomic absorption spectrometry detector were optimized, final conditions were set and optimal conditions for separation process using HPLC were investigated. Calibration dependences for selenium compounds were measured and analytical figures of merit were investigated. In conclusion, a coupled method HPLC- EcHG- QFAAS for determination of individual selenium compounds was proposed, and it was tested on urea samples. Calibrations for these measurements were investigated and analytic characteristics were calculated. Based on these comparisons it can be said that proposed method allows the determination of selected selenium compounds in both aqueous and urea matrices. Subject words: Spectroscopy, analytical chemistry Key words: Atomic absorption...

Master of Science / Department of Civil Engineering / Natalie Mladenov / In the United States approximately 37% of the 4 trillion kWh of electricity is generated annually by combusting coal (USEPA, 2013). The abundance of coal, ease of storage, and transportation makes it affordable at a global scale (Ghose, 2009). However, the flue gas produced by combusting coal affects human health and the environment (USEPA, 2013). To comply with federal regulations coal-fired power plants have been implementing sulfur dioxide scrubbing systems such as flue gas desulfurization (FGD) systems (Alvarez-Ayuso et al., 2006). Although FGD systems have proven to reduce atmospheric emissions they create wastewater containing harmful pollutants. Constructed wetlands are increasingly being employed for the removal of these toxic trace elements from FGD wastewater. In this study the effectiveness of using a constructed wetland treatment system was explored as a possible remediation technology to treat FGD wastewater from a coal-fired power plant in Kansas. To simulate constructed wetlands, a continuous flow-through column experiment was conducted with undiluted FGD wastewater and surface sediment from a power plant in Kansas. To optimize the performance of a CWTS the following hypotheses were tested: 1) decreasing the flow rate improves the performance of the treatment wetlands due to an increase in reaction time, 2) the introduction of microbial cultures (inoculum) will increase the retention capacity of the columns since constructed wetlands improve water quality through biological process, 3) the introduction of a labile carbon source will improve the retention capacity of the columns since microorganisms require an electron donor to perform life functions such as cell maintenance and synthesis. Although the FGD wastewater collected possessed a negligible concentration of arsenic, the mobilization of arsenic has been observed in reducing sediments of wetland environments. Therefore, constructed wetlands may also represent an environment where the mobilization of arsenic is possible. This led us to test the following hypothesis: 4) Reducing environments will cause arsenic desorption and dissolution causing the mobilization of arsenic. As far as removal of the constituents of concern (arsenic, selenium, nitrate, and sulfate) in the column experiments, only sulfate removal increased as a result of decreasing the flow rate by half (1/2Q). In addition, sulfate-S exhibited greater removal as a result of adding organic carbon to the FGD solution when compared to the control (at 1/2Q). Moderate selenium removal was observed; over 60% of selenium in the influent was found to accumulate in the soil. By contrast, arsenic concentrations increased in the effluent of the 1/2Q columns, most likely by dissolution and release of sorbed arsenic. When compared to the control (at 1/2Q), arsenic dissolution decreased as a result of adding inoculum to the columns. Dissolved arsenic concentrations in the effluent of columns with FGD solution amended with organic carbon reached 168 mg/L. These results suggest that native Kansas soils placed in a constructed wetland configuration and amended with labile carbon do possess an environment where the mobilization of arsenic is possible.

Thesis (MEng) -- Stellenbosch University, 2014. / ENGLISH ABSTRACT: The copper sulphate leach solutions produced during the final pressure leach stages in base metal refinery processes contain low concentrations of other precious metals (OPMs, namely Rh, Ru and Ir ) and impurities in addition to the base metals (BMs) of interest. Se and Te impurities, in particular, must be removed from the leach solution before it is fed to copper electrowinning because these species have adverse effects on electrowinning efficiency. Currently, these elements are being precipitated from the leach solution with sulphurous acid. Se precipitation is satisfactory but Te removal still proves challenging. Previous studies have shown that tellurium can either be precipitated as cuprous telluride from copper sulphate solutions by reduction with sulphurous acid alone, or by the addition of SO2 as a precipitating agent and metallic copper as an additional precipitating agent. The objective of this study was to evaluate the effects of different process variables on Te and Se recovery in order to propose operating conditions at which increased tellurium precipitation can be achieved with minimal co-precipitation of base metals of interest (notably Cu and Ni). This would also aid in the development of a better understanding of tellurium and selenium precipitation mechanisms in CuSO4-H2SO4 medium. / AFRIKKANSE OPSOMMING: Die kopersulfaat logingsoplossing wat gedurende die finale druklogingstadia in basis metaal raffinaderye produseer word bevat, behalwe vir die basis metale van belang, ook lae konsentrasies ander edelmetale (AEM, naamlik Rh, Ru, en Ir) sowel as onsuiwerhede. Se en Te onsuiwerhede, in die besonder, moet vanuit die logingsoplossing verwyder word voordat die oplossing na die koper elektrowinning gevoer word omdat hierdie spesies negatiewe effekte op die elektrowinning effektiwiteit het. Hierdie elemente word tans met swaweligsuur vanuit die logingsoplossing gepresipiteer. Se presipitasie is voldoende, maar die Te verwydering bly steeds problematies. Vorige studies het getoon dat tellurium as kuprotelluried vanuit kopersulfaat oplossings presipiteer kan word deur middel van reduksie met swaweligsuur alleen, of met die byvoeging van SO2 as presipiteermiddel en metallieke koper as addisionele presipiteermiddel. Die doelwit van hierdie studie was om die effekte van verskillende prosesveranderlikes op Te en Se presipitasie te ondersoek ten einde bedryfstoestande voor te stel wat verbeterde tellurium presipitasie toelaat met minimale kopresipitasie van basis metale van belang (hoofsaaklik Cu en Ni). Dit sal ook bydra tot die ontwikkeling van ʼn beter begrip van die tellurium en selenium presipitasie meganisme in ʼn CuSO4-H2SO4 medium.

Studies were conducted to investigate the effects of in ovo injection of selenium (Se) either as seleno-methionine (Se-Met) or sodium selenite (Na2SeO3) into the yolk of incubating eggs on tissue Se concentration, embryo livability, lipid peroxidation, immune response and growth performance. When white-shelled eggs were injected with 0.1ml of solutions providing 0, 2.5, 5, 10 or 20 μg Se/egg, no detrimental effects on embryo viability at 20 days of incubation were noted. The effects on tissue Se concentrations suggested that Se-Met and Na2SeO3 were metabolized differently by the chick embryo. In a subsequent study using injection doses up to 60 μg/egg, a greater linear response in tissue Se was obtained with Se-Met, compared with Na2SeO3 (P < 0.01). Minimal changes in heart and breast muscle Se concentrations were noted above the 40 μg dose when Na2SeO3 was used (P > 0.05). In a study with broiler eggs, injection doses of 0, 2.5, 5, 10, 20 and 40 μg Se/egg were used. Se-Met or Na2SeO3 at doses up to 40 μg Se/egg had little effect on embryo viability. Injecting Se-Met resulted in greater tissue Se accumulation than Na2SeO3 at 20 days of incubation. In another study with broiler eggs using injection doses up to 40 μg Se/egg, Se-Met injection resulted in higher hatchability, reduced lipid peroxidation in the lung and heart muscle of the embryos after 20 days incubation and higher Se concentrations in heart and breast muscle of hatched chicks through 7 days and in lung through 21 days of growth. In a feeding trial with broiler breeder hens, adding 0.3 mg/kg of Se as Se yeast or Na2SeO3 to the diet improved tissue Se status at hatching of progeny chicks. Taken together, these results indicate that injection of Se into the yolk of incubating eggs may be useful for enhancing Se status during embryonic and early post-hatch development. Therefore, the improvement in Se status using this method in conjunction with dietary Se supplementation of breeder hens would be much greater than with only using dietary supplementation.

No description available.

Oxidative stress, lipid peroxidation, and endotoxaemia with cytokine-mediated injury have been implicated as factors in the pathogenesis of non-alcoholic fatty liver disease (NAFLD). The degree of insulin resistance together with co-existing inadequacies of vital antioxidant defence mechanisms may be important determinants of progression to fibrosis in patients with non-alcoholic steatohepatitis (NASH). Current therapies are targeted at improving insulin sensitivity as well as addressing hepatic repair including anti-inflammatory strategies. Anti-oxidants remedies have also been tested but the role of selenoenzymes with antioxidant action, namely thioredoxin reductase 1 (TR1) and glutathione peroxidase 1 (GPX1) have been ignored. The aim of this thesis is to investigate the role of selenium in the pathophysiology of NAFLD both in vitro and in vivo. The in vitro studies used cell lines representing the cell types involved in the disorder; hepatocytes (C3A line) and hepatic stellate cells (LX-2 line). In order to assess the influence of selenium status and selenoenzymes expression on the pathogenesis of NAFLD it was necessary to develop a culture system which allowed good cell viability in selenium free culture medium. This was achieved by the use of an insulin and transferrin (IT)-supplemented medium which importantly was free of any animal serum additions. Using this IT culture medium, selenium addition (as selenite) produced a significant increase in the expression of GPX1 and TR1 in both C3A and LX2 cells. TR1 and GPX1 were expressed at similar levels in both C3A and LX-2 cells. It was also necessary to develop an in-vitro model for fat loading C3A cells to mimic fatty liver pathophysiology. Two models of fat loading were investigated. One model used lactate, pyruvate, octanoate and ammonium (LPON). LPON has been previously used to increase the functionality of C3A cells but it was observed that fat droplets accumulated in these LPON treated cells. Dissection of the agents in the LPON revealed that octanoate was the factor that increased the triglyceride accumulation. Interestingly, octanoate also increased the expression of TR1 and GPX1, suggesting that it could induce oxidative stress leading to the induction of selenoenzymes to afford a protective defence mechanism. In the second model, oleate and/or palmitate were used to fat-load C3A cells. These cells had significantly higher triglyceride content than the LPON-fat-loaded cells. However, oleate and/or palmitate treatments did not increase the expression of either TR1 or GPX1 in C3A cells suggesting perhaps these cells were not under oxidative stress. LPON and oleate/palmitate were also capable of fat loading LX2 cells. Selenium-supplementation of C3A and LX-2 cells efficiently protected (measured by their lactate dehydrogenase retention) them from oxidative damage induced by t-butylhydroperoxide. This suggests that selenium supplementation through its incorporation into selenoenzymes could protect the cells from the oxidative damage. The role of selenium was also investigated in the regulation of α-1 pro-collagen mRNA expression. In LX-2 cells, the expression of α-1 pro-collagen mRNA was unaffected by the selenium status of the cell. Similarly the selenium status of C3A cells had no effect on modifying α-1 pro-collagen mRNA of LX2 cells when co-culture or conditioned medium experiments were performed. These results suggest that LX-2 cells were already largely activated and at a stage unable to be ameliorated by selenium treatment. In contrast, studies on C3A cells revealed that TGF-β1 (common inducer of α-1 pro-collagen mRNA in hepatic stellate cells) dramatically increased the expression of α-1 pro-collagen mRNA in C3A cells to the levels observed in LX-2 cells. More interestingly, selenium supplementation of C3A cells notably decreased α-1 pro-collagen mRNA expression in response to TGF-1. In the in vivo study, plasma selenium in type 2 diabetics (high risk of developing NAFLD) were inversely related to the body mass index and in most patients selenium levels were below that required to maximally express GPX1 in red cells. Furthermore, type 2 diabetics had lower plasma selenium levels compared to the healthy control group. Collectively, this suggests that in the UK population, obesity is a risk factor for both insulin resistance and decreased selenium status leading to sub-optimal antioxidant protection. In conclusion, this study provides evidence that selenium through increasing the expression of selenoenzymes is beneficial in protecting liver cells from oxidative stress. Furthermore, selenium is capable of suppressing α-1 pro-collagen mRNA expression in hepatocytes although not in activated hepatic stellate cells. Taken together these data support the view that suboptimal selenium intake in the UK may be a risk factor in the pathogenesis of NAFLD.