Dissertations / Theses on the topic 'Mangaung'

Magister Public Health - MPH (Public Health)
Teenage pregnancy remains a complex issue globally. According to the World Health Organisation (2014), the average global birth rate of girls aged 15-19 years was 49 per 1000 births reported globally. In South Africa, the general household survey conducted in 2014 revealed that 5.6% of females 14-19 years were reported to have been pregnant in 2013, with teenage pregnancy increasing by age from 0.8% for the age group of 14 years to 11.9% for teenagers aged 19 years. In South Africa, a range of health policies and programs exist to address teenage pregnancy, including school-based sex education, peer education programmes, adolescent friendly clinic initiatives and mass media interventions. Despite such initiatives, the number of teenagers becoming pregnant remains high. Teenage pregnancy reported in Mangaung district is 7%, which is three times more than the provincial target of 2% for teenage pregnancy. This research therefore aimed to explore the reasons behind teenage pregnancy in Heidedal, Mangaung District, Free State Province, South Africa. Two in- depth interviews were conducted, one with twelve teenage mothers and the other with four key informants who were selected based on insight and experience they possess in working with teenagers. The key informants suitable for the study included a nurse, life orientation teacher, ward councillor and a counsellor working for a non-governmental organization that supports the implementation of youth programmes in the health facility. Thematic analysis was used to analyse data and key themes, afterwards concepts were interpreted so that explanations could be constructed to answer the research aim and objectives. The study aimed to contribute to understanding reasons behind the high teenage pregnancy rates in Mangaung District. This information will be useful to policy makers in developing policies and strategies that will address factors identified to be influencing teenage pregnancy.

This study seeks to focus on the extent to which the newly formed Mangaung Metropolitan Municipality (MMM) in the Free State Province of South Africa has been able to close the socio-economic gap between the former homelands’ socio economic status and the current MMM such that the local development in former homeland areas post 1994 is scruitinised with the MMM serving as a unit of study for the scrutiny. A brief history of the three towns that form the Mangaung Metro Police such as Bloemfontein, Botshabelo and Thaba Nchu, the population statistics and economic sectors contributing to its economic environment will be provided. The study will also look into the historical background of Local Economic Development and practices in South Africa.

Thesis (M. Tech. (Environmental Health)) - Central University of Technology, Free State, 2014
In the battle to sustain and produce quality food that is safe and affordable, the limited legislative and regulatory environment continues to allow opportunities for food to become contaminated during processing. The degree of contamination distributed over the final food product (including meat products) depends upon several factors that include knowledge and behaviour of the food handlers, equipment, the hygiene habits of personnel, and the monitoring that takes place at food processing plants (including butcheries). The current study was conducted in five selected butcheries (forming 15% of the registered butcheries at the time the study was conducted) in the Mangaung Metropolitan municipal area, purposely targeting the ones registered with the municipality. The hygiene practices of meat handlers were assessed (through self-administered questionnaires) because meat is a perishable product that requires labour intensive processing for production of quality products. Thus, mishandling by food handlers may create and maintain conditions favourable to microbial contamination. Furthermore, the study assessed and characterised microbial contamination on working surfaces and utensils through swabs as well as bioluminescence instrument [Adenosine Tri-phosphate (ATP) Hygiena] for cleanness of the working environment. Concomitant to the above, meat handlers’ hands and aprons were also assessed for possible microbial contamination as well as their characterisation. Lastly, aerosolised microbes [through an air sampler (Surface Air System) SAS Super 90] were also collected for iv quantification and identification during working hours as airborne microbes can settle on working surfaces and/or utensils as a result of movement of workers and other related working processes. Statistical points such as correlations, standard deviations, group standard deviations as well as significant differences were captured per respective chapter where necessary. Data reported in this study is over 3 month period with two weeks intervals during sampling and thus reported as either weekly or rounds between sampling periods. The results of the current study indicate that the food safety objectives are negligibly achieved, indicating a need for proper food safety training which is audit based. On administration of a questionnaire, food handlers showed poor knowledge of food safety awareness coupled with poor attitude and behaviour in terms of food safety. The five butchery premises were further examined regarding the airborne and surface microbial loads, as well as that of the food handlers’ hands, during processing. The microbial loads in the air appeared to comply with the suggested limits at all the sampled butcheries. Microbial loads on meat contact surfaces showed levels conforming to the South African standard or guideline of 1 × 102 cfu.m-2. Total Coliforms on hands and on aprons were compared to the general microbial target value of <2.5 cfu.m-2 as suggested by literature. In this study, Matrix Laser Desorption Time of Flight Mass Spectrophotometer (MALDI-TOF MS) was found to be an accurate, rapid and cost effective method towards v identifying of foodborne pathogens and spoilage bacteria including yeast. Moreover, in recent years South Africa’s meat scandals have increased consumer awareness and the demand for food safety. Section 11 of the Meat Safety Act (Act no. 40 of 2000) stipulates that every abattoir must utilize an independent inspection service appointed by the department of agriculture to ensure that meat of high quality and wholesomeness is produced. However, once the meat and meat products leave the abattoir, they are under the jurisdiction of the local authorities who rely only on visual assessment as opposed to microbiological inspection in the maintenance of their hygiene and quality. Despite the high incidence of foodborne illnesses in both developed and developing countries; South African data on foodborne illness incidents is still insufficient. This could be attributed to the fact that in South Africa, legislation governing the acceptable standards of the levels of microbiota in the air and on food handlers’ hands is still inadequate. Additionally, lack of obligatory usage of Hazard Analysis Critical Control Point (HACCP) procedures in the meat premises poses a risk for economic productivity. In conclusion, the identification of airborne bacteria in the butcheries strongly suggests that in the planning of the existing establishments, the building layout, control of the traffic flow of personnel, the durability and imperviousness of floors, the ventilation system and the placement of the equipment were not carefully considered. This may play a role in the prevalence and proliferation of airborne microbes as the resulting establishments provide an environment conducive to the breeding of microbes. vi In regard to swabs, it was concluded that floors may present a high point of contamination possibly through aerosolization of microbial communities. Moreover, cleaning materials and hygiene practices need to be reviewed. The results of the administered questionnaire showed that food handlers should be sufficiently trained with regard to food quality management tools such as Good Manufacturing Practices (GMP), Hazard Analysis and Critical Control Point (HACCP) systems and food safety. The evaluation of meat contact surfaces for organic soils to determine their cleanliness using the rapid ATP bioluminescence testing can be convenient for everyone involved in the food chain since visual and touch inspection cannot be conclusive enough to meet regulatory requirements in terms of microbial counts.

Thesis (M. Tech. (Environmental Health)) -- Central University of technology, Free State, 2013
Introduction: Drinking water of poor quality can cause a variety of diseases and may even result in death. The impact of poor drinking water is a course for concern even in South Africa. Therefore, the physical, chemical and microbiological drinking water quality was investigated in the peri-urban area of Bainsvlei and the Woodlands Hills Estate in Bloemfontein, Free State. Materials and Methods: The water quality was assessed in 20 identified sampling sites for three series with ten weeks apart. These sites use treated municipal and untreated borehole water for drinking. The determinants analysed for were pH, electrical conductivity (EC), turbidity, temperature, Ca, Mg, Na, F, Cl, N, SO₄,N, Free chlorine, Al, As, CN, Fe, Mn, Pb, Hg, total coliforms and E. coli. The water samples were collected and analysed on site and in the laboratory. Both the physical and chemical determinants were measured using standard methods whereas the microbiological determinants were measured using the Defined Substrate Technology (DST) method. The measurements were first compared to the SANS 241 (2011) for compliance. The ANOVA tests were used to investigate if any seasonal variations existed in the water quality as well as to compare the levels of the determinants between borehole and municipal water. In the assessment of the overall drinking water quality of different water sampling sites the water quality index (WQI) was used. Results and Discussions: Significant effects were believed to exist if the p-values of the ANOVA and Scheffe tests were at a significance level of 5% (p < 0.05). The study results revealed that of the four physical determinants that were measured turbidity exceeded the standard in many sampling sites in the three series. Of all the chemical determinants, nitrates exceeded the standard. In the same way coliforms exceeded the standard in a number of sampling sites while E. coli was found in a few sampling sites in the first series. ANOVA tests revealed that seasonal variations existed between pH, EC, temperature, cyanide and iron at a significant level of 5% (p < 0.05) while the Post-hoc Scheffe test further revealed the series in which the effect existed. Similarly, the ANOVA tests revealed that the levels of the determinants between municipal versus borehole varied in pH, EC, Ca, Mg, Na, F, Cl, N, and SO₄ at a significant level of 5% (p < 0.05). The WQI showed that in all the series when combining the good and excellent category season 2 had the highest percentage of 80%, followed by season 3 with 79% and season 1 with 70%. Only borehole sampling sites were found in the poor, very poor and unsuitable categories. Similarly all the highest WQI values were found in borehole sampling sites. Conclusion: This study revealed that the water quality is of good quality in the Bainsvlei and Woodlands Hills Estate of the Mangaung metropolitan municipality in Bloemfontein, in the Free State, South Africa. The presence of E. coli, though found in a few sampling sites and the high levels of turbidity, nitrates and coliforms are of concern to public health.

Government’s mandate (national, provincial, and local government) requires that its communication on issues of service delivery should enhance access to information that enables the public to participate in the country’s transformation and in bettering their own lives and implementation of people–centred programmes. The primary objective of this study was to assess and determine the role of external government communication on service delivery at the Mangaung Local Municipality in the Free State. In this process, the researcher looked at trends in government communication, especially focusing on local government or municipalities. The secondary objectives was to provide an overview of the concept of local government communication, to establish and analyse the factors that contribute to the gap between local government communication and service delivery, to demonstrate how managing communication in local government can assist in service delivery and to offer a conclusion and recommendations, drawn from the attained results, regarding the role of external government communication on service delivery at the Mangaung Local Municipality, as well as any other problems hampering effective external local government communication. This assessment was prompted by the service delivery protests in certain areas in our country, including the Mangaung municipal area – and the origin of the increased momentum cannot be pinpointed. The culture of these protests in South Africa is not uncommon, because it is this very phenomenon that has delivered the country into democracy. However, the consequence, in the form of unavoidable violent incidents, is mostly regrettable. These service delivery stand–offs by communities have continued to occur – even during the current dispensation (the post–apartheid government), orchestrated by various factors. Although these factors have ranged from the locality of the municipality; related to a third force; political infighting, etc. the lack of communication to communities by local councillors, to keep their constituencies informed, is relevant for this study. To assess the problem, a literature study and empirical research were undertaken. The comprehensive literature study focused on issues of local government communication and service delivery. The following literature sources were consulted to ensure a broad and balanced review of secondary and primary sources of literature on the problem under review: textbooks; journals; magazines and newspapers; master’s dissertations and doctoral theses; Internet sources; Government Communication policy document, workshop reports, plans of action, and other documents published by the South African Government usedto identify specific guidelines and prescriptions for general government communication. These documents include the Constitution of the Republic of South Africa, the Municipal Systems Act (32/2000), and the Government Communication and Information Services’ (GCIS) government communicator’s handbook. The empirical research obtained the required information from people in the Mangaung municipal area, who pay municipal bills at the municipal pay points and who buy electricity at vending machines in Bloemfontein, Botshabelo and Thaba Nchu in the Free State, where this study was conducted. This study showed that local government or municipality is the link between communities and the broader government structure. If local government is able to implement more effective communication, then damage to the reputation and relationships will be minimised if any problem or crisis occurs. Until the late nineteenth century organisations, including local government, only communicated informally with the residents in their areas. However, the twentieth century saw both the organisations and the community becoming larger and more sophisticated with each having an increased impact on each other. What organisations had to do is to start to keep track of the impact on the community and also keep track of the public’s impact on the organisation. The mass media became very powerful, influential and specialised, which means that the person responsible for communication at an organisation or municipality had to have advanced communication skills. It was at this point that organisations, including local government, began to create specialised communication roles, such as Media Relations, Communication Research, Outreach and Community Liaison, and Marketing. All these roles became sub–systems of the organisational system. Local government or municipalities are responsible for the establishment of effective communication channels between themselves and their publics. Some communication channels used by national government with its own publics are good examples that can be adapted by local governments for their own purposes. A few of the local government communication channels includes mayoral izimbizos (now referred to as the Public Participation Programmes) and ward committees. The research findings revealed that external government communication at the Mangaung Local Municipality is a cause of concern and that it impacts negatively on service delivery. Hence, the researcher is of the opinion that serious intervention is needed in order to change and better the situation at this municipality. Recommendations have been made on how the Mangaung Local Municipality can improve its external government communication in order to improve and accelerated service delivery to its communities.
Thesis (MBA)--North-West University, Potchefstroom Campus, 2012.

This aim of this research is to explore two methods for procuring security services in South Africa. This research is a comparative case study between two correctional centers, which are the Mangaung Correctional Centre and the Kimberly Correctional Centre. The Mangaung Correctional Centre has been procured through Public-Private Partnership, where government procures services through a private party and the Kimberly Correctional Centre has been procured through the traditional public sector finance method. The main objectives of the study is to compare and contrast the costs of incarceration in these correctional centres; to evaluate the quality of security services provided in these two correctional centres as well as to examine the most economic, efficient and effective method of procuring security services. The research findings indicated that the incarceration costs for Mangaung Correctional Centre were far more than the costs for Kimberly Correctional Centre, which poses a threat of affordability for the Department of Correctional Services. The research study also found in terms of the quality of security services provided in Mangaung Correctional Centre, there have been no escapes or riots reported in the centre for a very long time, on the other hand, the research has found that there has been a compromise in the quality of security services provided in Kimberly Correctional Centre because the centre has experienced violent riots in the recent years and there has been security threats due to the loss of the master key. It emerged from the research findings that there is generally a lack of monitoring and evaluation especially when it comes to the issue of incarceration costs in Mangaung Correctional Centre because the costs have increased by more than 100 per cent since inception, this is far more than increase in average inflation for the period reviewed. The research concluded by providing recommendations for consideration of procuring security services in future. Some of the key recommendations made in this research are that before government enters into any major contract, unless the feasibility study confirms the affordability of the project, then the government should not pursue the project further. The research further recommended that the government negotiators represented in the negotiation processes and awarding contracts should be capacitated, more especially in the area of finance and law to ensure that they understand the complexities and technicalities involved during the processes.

Thesis (D. Tech. (Engineering: Electric)) -- Central University of technology, 2012
Because power generation relies heavily on electricity demand, consumers are required to wisely manage their loads to consolidate the power utility‟s optimal power generation efforts. Consequently, accurate and reliable electric load forecasting systems are required. Prior to the present situation, there were various forecasting models developed primarily for electric load forecasting. Modelling short term load forecasting using artificial neural networks has recently been proposed by researchers. This project developed a model for short term load forecasting using a neural network. The concept was tested by evaluating the forecasting potential of the basic feedforward and the cascade forward neural network models. The test results showed that the cascade forward model is more efficient for this forecasting investigation. The final model is intended to be a basis for a real forecasting application. The neural model was tested using actual load data of the Bloemfontein reticulation network to predict its load for half an hour in advance. The cascade forward network demonstrates a mean absolute percentage error of less than 5% when tested using four years of utility data. In addition to reporting the summary statistics of the mean absolute percentage error, an alternate method using correlation coefficients for presenting load forecasting performance results are shown. This research proposes that a 6:1:1 cascade forward neural network can be trained with data from a month of a year and forecast the load for the same month of the following year. This research presents a new time series modeling for short term load forecasting, which can model the forecast of the half-hourly loads of weekdays, as well as of weekends and public holidays. Obtained results from extensive testing on the Bloemfontein power system network confirm the validity of the developed forecasting approach. This model can be implemented for on-line testing application to adopt a final view of its usefulness.

Thesis (D. Tech.) - Central University of Technology, Free State, 2006
The occupational health and safety of South African farm workers have been largely neglected because of the emphasis specifically put on the industrial environment. Although some studies have been done on the pesticide exposures of farm workers, the occupational health and safety of farm workers have not been studied as a whole and therefore there is no comprehensive occupational health and safety programme for farm workers. The aim of the study was to compile an applicable occupational health and safety programme for crop farm workers in the Mangaung local municipal district. Twenty-five farms in this region were selected and a list that included the different activities on the farms, the number of workers on each farm and the work hours of the workers was completed. The different health and safety hazards and associated risks were identified on each of the selected crop farms. A hazard identification risk assessment (HIRA) was compiled and completed to rate the different health and safety risks. The results of the study indicated that the main activities executed on the farms were preparation and ploughing of land, planting of crops, application of pesticides and the harvesting of crops. The HIRA indicated eleven “high” risks, seven “moderate” risks and only one “low” risk. An applicable overall occupational health and safety programme that included the abovementioned “high, moderate and low” risks was compiled. Individual occupational health and safety programmes for the control of each identified hazard were designed. The suggested occupational health and safety programmes were presented to nine selected crop farm owners and/or managers as an identified focus group. They completed a questionnaire to indicate whether they found the suggested programmes feasible and acceptable. The majority indicated that the programmes were both feasible and acceptable. However, the focus group indicated that training of both farm owners/managers and farm workers in the Mangaung local municipal district is essential. The group further indicated that legislation that forces the farm owner/manager to implement occupational health and safety programmes are necessary. The designed occupational health and safety programme may thus now be implemented with applicable education and training.

Thesis (D. Tech. (Environmental Health)) -- Central University of technology, Free State, 2013
Some epidemiological studies suggest that exposure to high levels of electromagnetic fields (EMFs) may be linked with the development of adverse health effects. However there is still controversy on this matter. Due to rapid technological growth in the modern society, employees in the welding and electrical industries are highly exposed to electromagnetic fields and may be at a high risk for developing occupational diseases. The health effects which may result from exposure to electromagnetic fields are related to the strength and frequency of the fields. This study was conducted to (i) assess the exposure levels to EMFs in the welding industry, (ii) determine the possible health risks associated with exposure levels, and (iii) develop a health and safety model to guide the industry on how to reduce exposure to EMFs. The study was conducted in one mega welding company in the Mangaung Metropolitan Municipality. Welders, fitters and office workers (88 in total) gave consent to participate in the study and completed questionnaires (ethical clearance attached). Measurements of extremely low frequency EMFs were taken in workshop A, workshop B and working offices. Measurements for magnetic fields were taken at distances of 1, 2 and 3 meters (m) from the EMFs sources. The exposure levels of magnetic fields were very high in the workshops, with welders and fitters exposed to about 7.6 microtesla (μT). Electric fields were relatively low in all workstations. Participants in the study were experiencing symptoms of ill health such as headaches, sleep disorders, fatigue and distress. The symptoms reported by the workers were similar in the both groups (exposed and control). There is no clear relationship between recorded exposure levels and the development of the reported symptoms. The health and safety model was developed to guide the industry to reduce exposure to electromagnetic fields. The model describes the implementation of engineering and administrative control measures in an effort to reduce exposure to EMFs. The model also highlights the importance of wearing personal protective equipment to shield against EMFs amongst others. This study suggests that occupational exposure to high levels of extremely low frequency EMFs may increase the risk for development of chronic diseases such as leukaemia, brain and breast cancer and other diseases among highly exposed employees. Implementation of safety measures is necessary to reduce exposure to EMFs.

Thesis (D. Tech. (Clinical Technology )) - Central University of Technology, Free State, 2013
The HIV pandemic in South-Africa has created a new form of vulnerability for households with regards to food security and nutritional status which are vital components in the general care of HIV-infected individuals. The risk of nutritional deficiencies and malnutrition are predictors of disease progression and treatment in resource limited settings. Furthermore, HIV affects nutritional status by increasing the energy requirements, reducing food intake, affecting nutrient absorption and metabolism inadequacies due to cytokine activity and diarrhea. Several vitamins and minerals are important in fighting HIV infection because they are required by the immune system and major organs to attack infectious pathogens. Many of these micronutrients have been found to be deficient in HIVinfected persons and several studies were launched worldwide to investigate the feasibility of food assistance and nutrient supplementation. Nutritional supplementation has been advocated in HIV-infected persons especially in lowincome countries such as South Africa. Therefore, a study to evaluate the role of nutritional supplementation in HIV-positive patients becomes necessary, especially in a developing country such as South Africa. It is against this background that the present research was initiated to examine the influence of a nutritional supplement on the immune status and health status of HIVpositive/ AIDS adult individuals. The aim of the investigation was to determine if supplementation with a mixture comprised from specific minerals, vitamins and herbs over a period of one year, affected the haematological status, immune status, viral load and pulmonary function in forty (40) HIV-infected individuals living in the Mangaung Metropolitan, RSA. viii A quantitative, open-labeled, before-after clinical trial was conducted at the Central University of Technology, in Bloemfontein, Free State Province in the RSA. Socio-demographic and dietary intake questionnaires were completed. All data pertaining to anthropometric measurements, haematological status, immune status, viral load and pulmonary function were obtained my means of using standard procedures and technological equipment. The data were subjected to parametric and non-parametric statistical analysis. The results of the present investigation show that the eating pattern of this urbanized group of individuals reflects high energy (KJ) and macronutrient intakes coinciding with sub-optimal intake of Vitamin D and iodine. Of all the haematological variables the only statistical significant changes observed were increases in the median erythrocyte sedimentation rate (ESR) (p=0.0219) and mean cell haemoglobin concentration (MCHC) (p=0.0245) after six months of nutritional supplementation. At 12 months a statistical significant decrease in the median CD/CD8 ratio (p<0.0048), median Hematocrit concentration (p<0.0312), median mean cell volume (MCV) (p<0.0359), and median RDW (p<0.0273) accompanied a statistically significant increase in the MCHC (p<0.0003) at 12 months after supplementation. At 6 months 89% (CI95%: 73%; 96%) of the individuals showed a decline in viral load counts with a median percentage decline of 34% (CI95%: 73%; 96%). At 12 months 85% [CI95%: 68%; 94%] of the individuals show a decrease in viral load counts with a median percentage decline of 62.9% (CI95%: 50%; 78.6%) following the intake of the supplement. The main findings of the present investigation reveal that 68% (50%-81%) of the individuals show a statistical median increase (p=0.0302) of 16.9% (11.5%; ix 36.1%) in the Peak Expiratory Flow (PEF) at six months. A significant decrease (p=0.0484) in the median FEF75 of 28.1% (14%; 35.3%) is observed in 70% (53%-83%) of the individuals after 12 months of exposure to the supplement. No statistical significant changes are observed for FVC, FEV1, FEV1/FVC and FEF50 over the entire trial period. The present results suggest that a significant measurable decrease in viral load in HIV-infected individuals can be obtained by means of subjecting individuals to a nutritional fortification supplement strategy for 6 months or more.

Published Article
Objective: To determine the relationship between body mass index (BMI), energy intake and levels of physical activity of HIV negative and HIV positive women. Design: Cross sectional study. Methodology: A random sample of 500 pre-menopausal women within the two age group categories of 25-34 and 35-44 years was selected. Data on physical activity was obtained using an adapted Baecke questionnaire and categorized into low, medium, and high levels of physical activity. Weight and height were used to calculate BMI. Dietary intake was determined by means of a standardized food frequency questionnaire. Results: Sixty-one percent of younger women and 38% of older women were HIV infected. The vast majority of women (91%) had low levels of physical activity, while only 9% of the sample had physical activity levels that fell within the normal to high category. More than 50% of respondents were either overweight or obese (BMI above 25 kg/m2). BMI of HIV positive younger women was, however, significantly lower than that of HIV negative women. Median energy intakes were high (more than 10 000 kJ) for both HIV positive and HIV negative women. Conclusions: Reverting to a more traditional lifestyle, including diet and physical activity, could assist in addressing unfavorable BMI parameters of these women and improve health status and quality of life of HIV infected women.

Doctor Educationis
This study investigates how two groups of African pupils, namely the low and high performers in standard 9 mathematics classes in some high schools in Mangaung, construct meaning of their African cultural, individual African identity and performance in mathematics respectively. The observation underpinning this investigation is that social structural factors have not gained much attention in research as bases for explaining differentiated performance in mathematics, hence this study. To arrive at the findings mentioned below, the study used three quantitative instruments namely Mboya's Self-Description Inventory II (MSDI-II), Rotter's I-E scale and Tuekman's Mathematics Attitude Scale (MAS). Four hundred pupils who constituted the sample that responded to these questionnaires were controlled as to confounding variables like, gender, social class, exposure to mathematics and future aspirations relating to this subject. MSDI-II and Rotter's I-E Scale accessed data relating to signification of African individual identity while MAS and one of MSDI-Il's subscale, Maths Ability were 'triangulated' to access data relating to signification of performance in Mathematics. To triangulate findings on these two variables as well as to allow the sampled pupils' voices to be heard, discourse analysis was conducted on the open interviews with the two groups of low and high performing pupils in their respective schools. This qualitative approach also enabled the study to access information relating to signification of African Cultural Identity. No quantitative instrument was found suitable for this purpose. Although the study is careful not to make strong causal inferences between meaning construction (signification) and performance, the results show that (i) low performers are not sure about whether they are Africans or not since according to them African cultural identity implies an obsolete and primitive way of doing things. They are unable to identify with this. High performers see African Cultural Identity as involving lived experiences which challenge them to transform their despised status as Africans (ii) Low performers are not as positive as high performers about Africanness (individual identity) and (iii) they are also not positively inclined towards mathematics and their own ability to perform well therein, while high performers are very positive as they see doing well in mathematics as an act of struggle that would enable them to improve their social standing and that of other Africans. On the basis of the above the study is able to conclude that low performers construct meaning of the mentioned factors in agreement with the dominant discourses that see Africanness as being primitive, incompetent and unable to adequately comprehend the intricacies of modem day subjects like mathematics. High performers on the other hand tend to contest this negative definitions about what it means to be an African (identity, culture and performance in mathematics). They are thus positioned within counter-hegemonic ideology and discourses in as far as their meaning construction is concerned. Grounded on the above findings and conclusions, the study recommends that efforts should not be spared to enable the low performers (and/or pupils at risk of failing) to adopt positive meaning making strategies of high performers. These strategies may be accompanied by enhanced positive feelings about self and what one is capable of, which may in tum also impact positively on performance in mathematics, in particular. The research further argues that this goal may be achieved through curriculum enrichment, guidance, counselling and teaching, couched in the framework of African Renaissance. Therefore further research needs to be conducted that will elaborate clearly (i) what the implications of African Renaissance are on education, teaching, learning and mathematics curriculum in particular, (ii) what are the most effective means of transferring high performers' strategies of meaning construction to the low performers in the context of African Renaissance and (iii) how to strengthen and further sustain the positive meaning making strategies among high performers. Recommendations relating to curriculum enrichment in the context of Curriculum 2005 and Outcomes Based Counselling are also made as well as suggestions for future relevant research based on the concepts generated in this research.

Thesis (M. Tech. Public Management)) -- Central University of Technology, free State, 2013
During 2009 the State of Local Government in South Africa 2009 Report, (2009:71-75) showed that much of local government is in distress and it also showed that much of the local government municipalities faced serious challenges such as the lack of service delivery, poor financial management and weak integration between the Integrated Development Plan (IDP) and the Local Economic Development (LED). To improve the performance of the municipalities, the national government approved a comprehensive Local Government Turnaround Strategy (LGTAS) that serves as a country-wide intervention with the aim to address the communities‟ increasing dissatisfaction with poor municipal services, as well as to improve the administrative and financial performance of all municipalities. The purpose of the study was to investigate the impact of the Local Government Turnaround Strategy (LGTAS) on public participation and good governance with respect to the Integrated Development Planning (IDP) process in the Mangaung Metropolitan Municipality. It was found during the literature review that although the Local Government Turnaround Strategy (LGTAS) was successfully incorporated in the Mangaung Metropolitan Municipality Integrated Development Plan Review of 2013/2014, more needs to be done to ensure that the medium-term priorities are effectively implemented to promote good governance, and effective service delivery of Mangaung Metropolitan Municipality. The study found that although the Mangaung Metropolitan Municipality has a well-planned and well-structured community engagement strategy to promote effective public participation, more needs to be done to ensure that the communities are effectively represented during the various public participation consultation activities to ensure that the needs of the majority of the communities are addressed. The study also found that the Mangaung Metropolitan Municipality has well-defined strategies to promote good governance in its Integrated Development Plan (IDP), the effective implementation remains a challenge.

Magister Public Health - MPH
Background: Over the past decade, South Africa has scaled-up its antiretroviral treatment (ART) programme in an effort to control the HIV epidemic. Interventions to support the rollout of ART include task shifting ART initiation to nurses at primary health care level and ensuring HIV adherence counselling at every visit by lay counsellors. Furthermore, community-based outreach teams work at the community level to follow up on patients and ensure that patients remain in care and are adhering to ART. Despite all these efforts, poor adherence to ART remains a pertinent problem. In 2016, the national adherence to ART rate among adult patients was estimated at 35% compared to 39% in Pule Sefatsa clinic in Mangaung district, Free-state Province. Aim: The aim of the study was to explore the factors that influence poor adherence to ART among patients receiving ART at Pule Sefatsa primary health care clinic in Mangaung district, South Africa. Methodology: A descriptive qualitative research approach was used. Two focus group discussions were conducted with health workers and community caregivers and 16 in-depth interviews were conducted with ART patients who are in care and those who had defaulted on their treatment. Audio recorded data obtained from these sources were transcribed verbatim and prepared for analysis. Thematic analysis was used for data analysis and the results were classified under various categories. Findings: Adherence to ART in Pule Sefatsa clinic was found to be influenced by medical related factors, socio-economic factors, health system factors and individual factors. The medical-related factor was the side effects of the medication. The socio-economic factors were stigma and discrimination, lack of family support, poverty and food insecurity. Health system factors that hindered adherence to ART were medication stock-outs, long waiting times and poor service delivery. The final group of barriers to ART adherence was related to the individuals using ART and these include patients forgetting to take treatment and feeling depressed.

This thesis explores South Africans’ relations to grond (land/soil) and water through two collaborative spoken word poetry projects. By investigating how collaborative poetic practices can be improved to respond to social-ecological changes, this study generates critical new knowledge for other poetry collectives to apply to their own practices. The principal methodology is practice-led and is focused by two projects – the first, themed around relations to grond that took place in Mangaung in early 2019, and the principal project, themed around relations to water, culminating in the production “What the Water Remembers” in Cape Town on 4 September 2019.

Disertacijoje nagrinėjami lantano manganitai, pasižymintys faziniu virsmu iš paramagnetinės į feromagnetinę būseną bei milžiniškos neigiamos magnetovar-žos efektu. Tiriami magnetovaržos ir jos anizotropijos efektai silpnuose (iki  0,5 T) magnetiniuose laukuose bei stiprių impulsinių srovių ir magnetinių laukų sukelti efektai plonuose epitaksiniuose manganitų sluoksniuose. Pateikiami pasiūlymai tyrimo rezultatus panaudoti kuriant magnetinio lauko jutiklius, spar-čiųjų elektrinių impulsų formuotuvus bei amplitudės moduliatorius. Tiriant sil-pnų magnetinių laukų poveikį ultraplonųjų La-Sr-MnO3 sluoksnių elektriniam laidumui, buvo nustatyta, kad magnetovaržos anizotropijos ženklas ir vertė šiuo-se laukuose priklauso nuo sluoksnio storio. Pateiktas modelis, paaiškinantis eks-perimentinius rezultatus, paremtas vidutinio lauko artiniu ir įskaitantis sluoksnio struktūros kitimą kintant jo storiui. Aptiktas ir ištirtas grįžtamasis termoelektrinis nestabilumas, išaiškintos šio reiškinio atsiradimo priežastys. Pasiūlytas ir ekspe-rimentiškai realizuotas naujas ns trukmės elektrinių impulsų amplitudės modulia-vimo išoriniu magnetiniu lauku būdas, naudojant epitaksinius La0,87Sr0,17MnO3 sluoksnius. Disertaciją sudaro reziumė lietuvių ir anglų kalbomis, įvadas, šeši skyriai, pagrindiniai rezultatai ir išvados, literatūros sąrašas, publikacijų disertacijos tema sąrašas. Įvadiniame skyriuje nagrinėjamas problemos aktualumas, formuluojamas darbo tikslas bei uždaviniai, aprašomas mokslinis... [toliau žr. visą tekstą]
The objective of this dissertation is to investigate lanthanum manganites, which exhibit colossal negative magnetoresistance and phase transitions from the paramagnetic state to the ferromagnetic state. The magnetoresistance and its ani-zotriopy of thin epitaxial manganite films at low (up to  0.5 T) magnetic fields, as well as effects induced by strong pulsed magnetic and electric fields were in-vestigated. It was demonstrated how it can be used in the development of magne-tic field sensors, short electric pulse forming devices and amplitude modulators. It was found that in the case of ultra-thin La-Sr-MnO3 films, the sign and value of the magnetoresistance anisotropy at low magnetic fields depends on the thickness of the films. An explanation of these results was proposed using the mean field approach and taking into consideration that the structure of the films changes with its thickness. A reversible thermoelectrical switching effect was discovered and investigated. A new method for nanosecond duration electrical pulses amplitude modulation by an external magnetic field using La0.87Sr0.17MnO3 films was suggested and experimentally verified. This dissertation consists of the abstracts in Lithuanian and English, intro-duction, six chapters, the main results and conclusions and list of literature. The introduction contains topicality and problem, the aim of the work, tasks, scientific novelty, practical value, approval of the results, statement to be de-fended and... [to full text]

Contrairement a la legende, mangan ne connut la misere que durant les trois dernieres annees de sa vie. Toutefois, ce fut toujours un etre tourmente et excentrique. Pour ecrire, il avait besoin de se deguiser. Aussi, sur ses 950 et quelques poemes, pres des quatre cinquiemes se presentent comme des traductions. S'il arrive a mangan d'etre un traducteur fidele, il se pose plus souvent en critique, et la traduction devient re-ecriture: embellissements formels, substitutions d'idees, et meme parodie. Mais la traduction peut aussi etre re-creation, allant de l'adaptation de tel ou tel passage a l'appropriation pure et simple: dans ce dernier cas, le poeme anglais est independant de l'original. Ces diverses pratiques se retrouvent dans les trois principaux domaines exploites par mangan: poesie allemande, poesie orientale, et poesie gaelique. En outre, il arrive au poete d'attribuer ses oeuvres a des auteurs etrangers, reels ou inventes. En fait, mangan avait besoin de la traduction ou de son apparence pour s'exprimer: son moi echappait ainsi a la tyrannie du surmoi, en faisant semblant d'etre un autre. De plus, mangan haissait son pere: l'appropriation est une revanche contre les "peres" (les auteurs) et une mise en question des origines, par laquelle le poete affirme son originalite. La poesie de mangan est avant tout une lamentation sur la mort du passe (le sien et celui de l'irlande) et sur le vide du present, immobile et deja envahi par la mort. Cette vision desesperee (que tempere parfois un humour bizarre) s'exprime tantot en des vers elegiaques d'une subtile musicalite, tantot avec une extreme intensite, due au retour obsedant du refrain et a une syntaxe passionnee: mangan est une grande voix lyrique. La seconde partie de cette etude consiste en une bibliographie complete de mangan, qui recense la plupart des sources utilisees par le poete
Despite all traditional accounts, mangan only knew poverty during the last three years of his life. However, he always was a tormented, eccentric being. In order to write, he needed a mask. This is why most of his 950 odd poems are presented as translations. Though mangan can be a most faithful translator, he often plays the part of a critic, so that translating becomes re-writing: formal embellishments, substitution of ideas, or even parody. It can also end in re-creation, ranging from the adaptation of a single passage to complete appropriation, in which case the english poem is independent of its original. These various practices are found in the three main fields explored by mangan: german, oriental and gaelic poetry. Moreover, the poet sometimes attributes his own poems to foreign writers, real or invented. In fact, mangan needed translation, or the appearance of it, in order to express himself: pretending to be somebody else, his ego thus freed itself from the tyranny of the super-ego. Besides, mangan hated his father, and appropriation was a revenge on all "fathers" (the authors), as well as a rejection of origins which enabled him to assert his originality. Mangan's poetry is mainly a lamentation over the death of the past (whether his own or ireland's) and the emptiness of the motionless present, already haunted by death. This despairng vision (sometimes relieved by mangan's quaint humour) is expressed either in elegiac, melodious verse or with a tremendous intensity achieved through the use of an obsessive refrain or passionate syntax: mangan is first and foremost a great lyrical voice. The second part of this work provides a bibliography of mangan (primary and secondary material), listing most of the sources he used

The present work deals with the use of manganese oxide as a catalyst for positive electrode of fuel cells. The theoretical part is to analyze the problem of fuel cells, focusing on lowtemperature fuel cells. Are discussed and the methods of measurement and evaluation of properties of manganese oxide layer. The practical part deals with doping electrolytic manganese dioxide salts of divalent metals and monitoring their behavior in the cyclic voltammetry by the EQCM method.

The submitted paper covers manganese comprehensively. The introduction provides an overview of its basic physical and chemical properties. Its compounds are discussed individually, including their preparation, production, and practical uses. Furthermore, a list of analytical methods in which manganese is involved in the form of its compounds as reagents is included. The same section includes an overview of analytical methods whereby manganese and its compounds are detected, primarily in water industry processes. Attention is paid to manganese as a non-negligible constituent of the various parts of the environment. The section on manganese’s biogenic properties is interesting from the viewpoint of its toxicity as well as its role as an important biogenic element, indispensable primarily for mammals. The subsequent chapters discuss the various methods which are suitable, under specific conditions, for separation in the treatment of surface and underground water aimed at producing drinking, process, or industrial water, where a minimal concentration of this metal is required. The impact of the physical/chemical conditions which influence the efficiency of separation in a manner ranging from non-negligible to principal, is discussed further on. Given the specifics of treatment of surface [and] underground water, the chapters provide more details on the processes suitable for specific types of matrix and specific conditions. Next chapters sum up many years of the author’s observations and experiences in the various parts of the water management system, from the raw water source to treatment to distribution, focusing on surface and underground water separately. Last chapter describes the construction of a water treatment plant model, its launch and calibration, and the tests focused on separating manganese by way of coagulation using aluminium and iron sulphate.

The subject of this graduation thesis is low-cost alkaline power cells and especially electrodes with alternative catalyst made of MnOx + dopant. The thesis expands the bachelor´s thesis [1] and previous research [4] [12] [13] [14]. Volt-ampere characteristics and power characteristics of the katodes for AFC, subsidized with various dopants, are the outcome of this project. The project presents the optimalisation of preparation process of AFC electrodes. The aim is to prepair several electrodes with identical construction, which varies only with the type of the dopant.

Pasiūlytas mangano nustatymo metodas geriamajame vandenyje inversinės voltamperometrijos metodu naudojant gyvsidabrio plėvelinį elektrodą. Manganui nustatyti vandens mėginio nereikia chemiškai apdoroti. Optimalios nustatymo sąlygos: kaupimo potencialas –1,75 V, kaupimo trukmė 5–30 s, anodinis tirpinimas atliekamas naudojant kvadratinės bangos voltamperometriją. Mangano aptikimo riba kaupiant jį 30 s yra apie 0,4 μg l–1, o santykiniai standartiniai nuokrypiai darbiniame koncentracijų intervale ne didesni kaip 0,10. Realios kalcio, magnio ir geležies jonų koncentracijos geriamojo vandens mėginiuose netrukdo nustatyti manganą. Metodo palyginimas su standartiniu fotometriniu metodu parodė, kad jie yra ekvivalentiški, tačiau elektrocheminis metodas gali būti taikomas labai mažoms mangano koncentracijoms nustatyti, be to, jam netrukdo geriamajame vandenyje esantys geležies jonai. Chromo nustatymui cemente gali būti naudojamas katalitinės adsorbcinės voltamperometrijos metodas naudojant kabančio gyvsidabrio lašo elektrodą. Terpės sudėtis Cr(VI) nustatyti: 0,15 mol l-1 CH3COONa, 5 mmol l-1 dietilentriaminpentaacto rūgšties (DTPA), 0.7 mol l-1 NaNO3, pH = 6. Optimalios votamperometrijos sąlygos: kaupimo potencialas –0.9 V, kaupimo trukmė 5-10 s, kvadratinės bangos voltamperometrijos režimas. Cr(VI) aptikimo riba yra apie 0,05 µg l 1, santykinis standartinis nuokrypis neviršija 3%. Iš cemento mėginių chromas išekstrahuojamas vandeniu arba azoto rūgštimi. Bendras chromo kiekis... [toliau žr. visą tekstą]
There was proposed method for the determination of manganese in drinking water by inverse voltammetry using a mercury film electrode. The determination of manganese in drinking water does not need chemical treatment of a sample. Optimal detection conditions: accumulation potential of -1.75 V, accumulation time 5-30 s, anodic dissolution is performed using square wave voltammetry. Manganese accumulation by the detection limit of 30 seconds is about 0.4 mg l-1, and the relative standard deviations of the working range of concentrations do not exceed 0.10. Actual calcium, magnesium and iron ion concentration in samples of drinking water does not influence the manganese determination. Method comparison with a standard photometric method showed that they are equivalent, but the electrochemical method can be applied in very small concentrations of the manganese, in addition, it does not influence the iron ions in the drinking water. Determination of chromium in cement can be performed by catalytic adsorption voltammetry method using a hanging mercury drop electrode. The medium composition for Cr (VI) determination: 0.15 mol L-1 CH3COONa, 5 mmol l-1 diethylenetriaminepentaacetic acid (DTPA), 0.7 mol l-1 NaNO3, pH = 6. Optimal voltammetry conditions: accumulation potential of -0.9 V, accumulation time 5-10 s, square wave voltammetry mode. Cr (VI) detection limit is about 0.05 mg l-1, the relative standard deviation does not exceed 3%. Chromium was extracted from the cement samples... [to full text]

Przeprowadzone badania dla szeregu zwi zków kompleksowych Mn(II) wymagały zastosowania dwóch oddzielnych technik eksperymentalnych. Do bada kompleksów w roztworze zastosowano potencjometri , dla stałych zwi zków kompleksowych monokrystaliczn analiz rentgenowsk . Zarówno badania w roztworze, jak i w fazie stałej potwierdzaj zdolno ci koordynacyjne wybranych do bada ligandów wzgl dem jonów Mn2+, jednak w roztworze tworz si wył cznie kompleksy jednordzeniowe, w fazie stałej natomiast kompleksy wielordzeniowe. Imidazol niezale nie od fazy tworzy tylko poł czenia jednordzeniowe. Na podstawie wykonanych bada potencjometrycznych w roztworze wyznaczono skład i stałe trwało ci kompleksów Mn(II) z 16. wybranymi ligandami organicznymi o ró nych wła ciwo ciach chemicznych, z których wi kszo charakteryzuje si aktywno ci biologiczn . Wybrane ligandy ró ni si liczb i rodzajem atomów donorowych, st d nale ało oczekiwa , i ró ne b d ich wła ciwo ci kompleksotwórcze. Wi kszo poł cze kompleksowych jonu Mn2+ charakteryzuje si nisk trwało ci m.in. ze wzgl du na słabe zdolno ci koordynacyjne wybranych do bada ligandów. Wyj tek stanowi kompleksy ligandów S – donorowych (kwas tiooctowy, kwas tioglikolowy, cysteina), które ze wzgl du na silne wła ciwo ci donorowe atomu siarki, tworz trwalsze poł czenia koordynacyjne z jonem Mn(II). Maksymalna liczba zarejestrowanych dla danego układu kompleksów wynosi dwa, st d mo na wnioskowa , i grupa karboksylowa – COOH w cz steczkach badanych kwasów karboksylowych oraz aminokwasów jest bidentatna. W kilku przypadkach powstaj słabe chelaty, gdy obok grupy karboksylowej koordynuje dodatkowo inna grupa funkcyjna np. grupa – OH (kwas glikolowy) czy – NH2 (glicyna, sarkozyna). Badania rentgenowskie na syntezowanych zwi zkach kompleksowych pozwoliły jednoznacznie wskaza sposób koordynacji kilku wybranych ligandów przez jony manganu(II) oraz opisa sfer koordynacyjn jonu centralnego Mn2+ w poł czeniach kompleksowych z tymi ligandami w fazie stałej. Wyniki tych bada potwierdziły w wi kszo ci przypadków dwupodstawny charakter grupy karboksylowej oraz wykazały, w odró nieniu od bada w roztworze, chelatuj cy charakter jonów metoksyoctanowych i brak udziału grupy – NH2 w cz steczkach sarkozyny w wi zaniu jonów manganu(II). Du e znaczenie maj wyniki bada dla układów kompleksotwórczych słabo zbadanych lub nie posiadaj cych cytowa w literaturze, szczególnie dla tych przebadanych kompleksowo w obu fazach tzn. dla poł cze manganu(II) z kwasem metoksyoctowym oraz z sarkozyn . Wielu autorów prac podejmuj cych temat zwi zków kompleksowych z jonem Mn2+ zgodnie stwierdza, e pierwiastek ten stwarza wyj tkowo du o problemów eksperymentalnych. Mangan wyst puj c na kilku stopniach utlenienia wymaga w niektórych przypadkach zastosowania odpowiednio dobranego reduktora. Ponadto wskazane jest równie prowadzenie miareczkowania potencjometrycznego w atmosferze gazu oboj tnego, co wymaga rozbudowania układu pomiarowego. Roztwory soli Mn(II) s trwałe tylko w rodowisku kwa nym, nale y je dodatkowo zakwasi , mierzone wi c st enie jonów wodorowych jest sum st e jonów uwalnianych w czasie reakcji kompleksowania oraz jonów wynikaj cych z dodatku kwasu, co nale y uwzgl dni w obliczeniach, dokonuj c pewnych modyfikacji. Ponadto charakter ligandów determinował wybór metodyki bada , gdy nale ało dostosowa eksperyment oraz obliczenia do rodzaju danego zwi zku. Dodatkowym utrudnieniem w pracy z opisywanymi zwi zkami była ograniczona rozpuszczalno w wodzie niektórych z nich. By mo e w/w problemy s przyczyn wielu nie cisło ci, rozbie no ci lub braku wa nych informacji w publikacjach zwi zanych z t tematyk . Stałe trwało ci s parametrami, które najpełniej charakteryzuj poł czenia kompleksowe w roztworze, dlatego otrzymane wyniki stanowi poszerzenie i uzupełnienie wiadomo ci z zakresu chemii koordynacyjnej zwi zków manganu(II). Ponadto ze wzgl du na biologiczn aktywno wi kszo ci z badanych ligandów oraz cenne wła ciwo ci manganu jako mikroelementu mog by przydatne w innych dziedzinach nauki.

Syftet med examensarbetet var att undersöka manganhaltens inverkan på skärbarheten och de mekaniska egenskaperna i varmarbetsstål Dievar samt kontrollera och undersöka hypotesen att material med låga Ac1 temperaturer maskinbearbetas svårare än material med högre temperaturer. 

Skärbarhet hos Dievar med olika Mn-halt från 0,084 till 1,59 vikts% studerades i härdat tillstånd med ett pinnfräsningstest. Skärbarheten karakteriserades genom mätning av verktygslivslängd och skärkrafter. Verktygslivslängd bestämdes av fasförslitningsutvecklingen på verktyget. Förslitningsmekanismer studerades på verktygets spån- och släppningssidor med hjälp av svepelektronmikroskop (SEM). Dragprov vid rums- och förhöjd temperatur genomfördes för att studera mangans inverkan på hållfasthetsegenskaper hos Dievar. Mikrostrukturen av stålen i härdat och anlöpt tillstånd undersöktes i SEM. Ac1 temperatur i stålen uppmättes med dilatometer.

Mangan visade sig ha en positiv inverkan på skärbarheten i Dievar. Verktygets livslängd var två gånger längre vid pinnfräsning av Dievar 1,59 vikts% Mn i jämförelse med Dievar 0,084 och 0,27 vikts% Mn. Mer påkletningsbenägna stål med lägre Mn-halt orsakade mer adhesiv nötning och urflisning av fräsens skäregg. Detta ledde till att förslitningen utvecklades hastigare under bearbetningen av Dievar med lägre Mn-halt.

De uppmätta skärkrafterna under bearbetning förklarade inte skillnaden i skärbarheten mellan Dievar med olika Mn-halt; skärkrafter var lika i alla material.

Dievar med högre Mn-halt innehöll mindre primära molybdenrika karbider än Dievar med lägre Mn-halt. Detta berodde på att manganet minskade Ac1 temperaturen i Dievar.

Mn-halten i Dievar påverkade inte hållfasthetsegenskaperna vid rumstemperatur men visade en tendens att minska stålets hållfasthet vid hög temperatur.

De genomförda undersökningarna bekräftade inte hypotesen att material med lägre Ac1 temperaturer har sämre maskinbearbetbarhet än material med högre temperaturer. Dievar 1,59 vikts% Mn hade betydligt lägre Ac1 temperatur än andra Dievar-material samt modifierat Orvar men visade sig vara lättare att bearbeta.

The aim of the study was to investigate influence of manganese content on the machinability and mechanical properties of a hot-work tool steel Dievar and verify a hypothesis that materials with low Ac1 temperatures are more difficult to machine than steels with higher Ac1 temperatures.

Machinability of Dievar with varying manganese content from 0,084 to 1,59 wt% was investigated in the hardened condition in the milling operation. The machinability of the steels was characterized by measuring tool life and cutting forces during machining. The tool life was estimated by measuring flank wear on the tools. Wear mechanisms were investigated on the clearance and rake faces of the tools by SEM. Tensile tests at room and elevated temperatures were carried out to examine the manganese influence on the mechanical properties of Dievar. Microstructure of the steels in hardened and tempered condition was investigated by SEM. Dilatometer tests were done to determine the Ac1 temperature for the steels.

Manganese content showed to have a positive effect on the machinability of Dievar. Two times longer tool life was reached when end milling Dievar 1,59 wt% Mn comparing to end milling Dievar 0,084 and 0,27 wt% Mn. More adhesive wear and chipping were observed on the tools after end milling the lower manganese containing steels. This resulted in more progressive wear and shorter tool life during machining of these steels.

The measured cutting forces could not be related to the difference in machinability of the steels with different manganese content. The generated cutting forces were similar for all the tested steels.

Dievar with higher manganese content contained less primary molybdenum-rich carbides in the microstructure. It was related to the lower Ac1 temperature of Dievar 1,59 wt% Mn comparing to the lower manganese containing steels.

The manganese content showed no influence on the tensile properties of Dievar at room temperature and a tendency to a slight decrease in yield and ultimate strength at the elevated temperature.

The machinability tests carried out in the present study did not confirm the hypothesis that materials with low Ac1 temperatures have poor machinability.  Dievar 1,59 wt% Mn had much lower Ac1 temperatures than the other Dievar steels and the modified Orvar steel but showed to have an improved machinability compared to the others.

The aim of my diploma thesis was to explore the influence of manganese ions put into nickel nitrate structure. The attention was focused mainly on the stabilization of nickel nitrate a modification, which could not change into b modification. The theoretical part of my thesis focused on applied materials, kinds of acumulators, basic parameters of acumulators and the description of chosen methods of measurement employed. It contained the electrodeposition, the impedance spectroscopy and the cyclic voltammetry. The task of the experimental part was to measure the effect of manganese ions put into potassium hydroxide structure. Proportions of Ni (nickel nitrate) : Mn (manganese nitrate) 10:0, 7:3, 5:5, 6:1 and 6:4 were blended for the measurement. By means of the electrodeposition, there was a thin layer of nickel hydroxide with an admixture of manganese ions from nickel nitrate and manganese nitrate dilution put on the nickel plate. After the spread of the thin layer on the nickel plate, the measurement by the method of cyclic voltammetry followed. The next task consisted in trying to add KOH (potassium hydroxide) anionic and cationic surfactant into the dilution.

This thesis describes possibilities removal of iron and manganese from the water. The first part of the thesis describes the sources and forms of iron and manganese in water, the health limits and possibilities removal of iron and manganese from the water. Contact filtration and materials used for contact removing of iron and manganese are described in more detail. The second part describes using materials Birm, Greensand and Semidol in practise. There i also described the experimental removing of iron and manganese by these three materials.

This work includes experimental examination of the hypothesis, affirming that bacteria’s, oxidising iron and manganese can grow in some Lithuanian water treatment and can increase the removal of iron and manganese substances from the water. The novelty is that the method of identification and cultivation of iron bacteria’s presented in the foreign scientific publications was improved and adapted to research of such micro-organisms existing in the quartz sand filter media in the Lithuanian equipment of water treatment plant. For the first time in Lithuania there was examined quantitative distribution of iron and manganese oxidising micro-organisms in the sand thin coating in filters of drinking water purification and were found regularity and dependency of iron bacteria’s activities on the main technological parameters in removal of iron and manganese substances from the water.

Electrical resistivity, dielectric constant, thermoelectric power, magnetic susceptibility, magnetization, and electron paramagnetic resonance measurements carried out on MPr2W2Oio (M = Cd, Co, Mn), CdRE2W20 ,o (RE = Y, Nd, Sm, Gd-Er), RE2W20 9 (RE = Pr, Nd, Sm-Gd), CuEu2W2Oio and Cu3Eu2W4 0 i8 compounds revealed an insulating State and both a weak hole and electron conduction as well as a paramagnetic state above 4.2 K for all compounds under study. Only for MnPr2W2Oio a ferrimagnetic order below the Curie temperature Tc = 45 K. was observed. The tungstates containing Y, Sm and Eu elements showed a weak response to the magnetic field characteristic for the multiplet widths comparable to the thermal energy. The broadband dielectric spectroscopy measurements revealed anomaly large value of the relative permittivity (er=884) for MnPr2W2Oio, the smaller one (er=l 56) for CoPr2W2Oio and the smallest one (er=22) for CdPr2W2Oio at Iow frequency (v=0.1 Hz) and above room temperature in the insulating and paramagnetic State. Below 273 K the relative permittivity (sr~24) does not depend significantly on frequency. For all CdRE2W2Oio tungstates (RE = Y, Nd, Sm, Gd-Er) a relatively Iow dielectric permittivity (er ~ 15) was also found. In case o f CuEu2W2Oio £r ~ 29 and for Cu3Eu2W4 0 is £r ~ 217 were measured. The main conclusion is that only these ions which have the unscreened electrons on the unfilled shells are responsible for the colossal dielectric effect. All the tungstates under study show the values o f the magnetic permittivity ^ir < 1.023, characteristic for the paramagnets. Some o f them like as Gd2W2C>9, CdNd2W2Oio and CdGd2W2Oio showed the superparamagnetic-like behaviour connected with the weak spinorbit coupling.

Uppsatsen syftar till att undersöka ungdomars reception av fenomenet manga/anime på ett etnografiskt arbetssätt, avgränsat med begreppet ungdomskultur. Fokus ligger på två mangayttringar som närmast berör ungdomar: shōjo för flickor och shōnen för pojkar. Resultatet redovisas i tre olika teman: Estetik/Stil, Makt/Könsroller och Berättelser/Myter,vilka tolkas med hjälp av ett raster på textuell, kontextuell och sociohistorisk nivå.Undersökningen är kvalitativ med sju ungdomar som informanter, och empirin består avfältanteckningar, fotodokumentation och intervjuer.Ungdomarnas fascination av mangaserier kan delvis förklaras med att de ritas i ett utstuderat ”filmiskt” maner, med snabba bildväxlingar och många olika bildvinklar, och delvis med att läsaren kan följa protagonistens utveckling under många år, parallellt med sin egen utveckling till ett vuxnare jag. Kulturyttringen uppmuntrar även till eget medskapande och egenamatörmanga-produktion, vilket medför att många ungdomar publicerar sitt eget material,både i pappersform och på internet. Detta gör fenomenet förhållandevis ohierarkiskt.Manga/anime-traditionen är ofta ironisk och lekfull, motiven i den tidiga sekventiellabildkonsten i Japan hämtades från nöjes- och teatervärlden, men under den flamsiga ytan döljsofta allvarliga resonemang. Berättartraditionen kan uppfattas utifrån tre olika modus: vardagligt, humoristiskt och poetiskt. Ungdomarna kan i postmodernistisk anda ta del av det främmande och egendomliga, men kan också; när de själva vill, stänga av och avskärma sigifrån det.Estetiken betecknas av eklekticism, brottstycken, lekfull inställning till form och konventionoch raserandet av hierarkiska traditionerna. Könsroller utmanas med crossdressing, och demanliga protagonisterna ritas ofta med påfallande feminina anletsdrag. Uppsatsen beskriverdetta med bakgrund av queerteoriska tankegångar, där en given norm ifrågasätts. Läsandet avserietidningar har nästan alltid betraktats nedlåtande, med någon form av moralpanik i sitt kölvatten. Detta kan betraktas som en reaktion mot en pågående modernisering. Resultatet av uppsatsen visar inte på någon större förändring i det traditionella könsrollstänkandet, men en viss omformulering pågår.

This master thesis has been done in cooperation with Sweco Viak AB in Sundsvall. The aimwith the project is to investigate the purifying effect of percolation filter due to iron andmanganese. The overall goal was to investigate how the parameters surface load,sandfractions, and burden time affect the purifying effect. The expectation is to optimize thedesign and find a demouldning of the filter that gives sufficient purifying with a highersurface load. As an attempt to accelerate the curing of the filter, experiments with a layer ofsand which surface has been covered with manganese ore (MnO2) on top of the filter havebeen done. As test filters 10 L bars were used and the experimental work was performed at thewaterworks in Hassela and Munkbysjön. In Hassela different sandfractions were tested. The manganese was very easy to oxidize andno difference in the reduction of manganese content in the water between the different filterswas observed. The iron was on the other hand very difficult to oxidize and no reduction of theiron content was obtained even though the water was aerated before entring the filters. Thismight occur when the iron is bounded in humuscomplexes. When it comes to the differentsandfractions, the fine sight can not be recommended as a method to treat water in Hassela asit didn’t work with a surface load of 0,2 m/h. With those results in mind percolationfilter isnot a method that can be recommended in Hassela. At the waterwork in Munkbysjön experiments were done with sand which surface had beencovered with MnO2. The difference in curing time was barely measurable which in this casemakes it unnecessary to use the preparated sand. When the surface load was increased thereduction of manganese content was uneffected. Even the reduction of the iron content wassufficient although no aeration was used. A percolation filter could work very well inMunkbysjön, but experiments with even higher surface load and sand with a highercoarseness are to be recommended before a filter is established.
Detta examensarbete är utfört i samarbete med Sweco Viak AB i Sundsvall. Rapportenbehandlar perkolationsanläggningar för rening av dricksvatten då grundvatten används sområvatten och dess reningseffekt gällande järn och mangan. Det övergripande målet medarbetet var att undersöka hur parametrar som ytbelastning, sandfraktioner, beskickningstiderpåverkar reningen i perkolationsfilter. Förhoppningen är att kunna optimera dimensioneringenoch finna en utformning som tål högre ytbelastning med bibehållen rening. För att försökapåskynda uppstarten av filtren har även försök gjorts med ett lager sand med brunstensbelagdyta överst. För att undersöka hur ovan nämnda parametrar påverkar reningen har pilotanläggningar körtsvid två olika vattenverk i Hassela resp. Munkbysjön. I Hassela gjordes försök med olika sandfraktioner. Manganet var mycket lättfällt och någonskillnad i reduktion av manganhalten mellan de olika filtren gick ej att urskilja. Järnet vardäremot mycket svårfällt och ingen reduktion av järnhalten erhölls i något av filtren, trotsluftning, vilket kan bero på att järnet är humusbundet. När det gäller de olikasandfraktionerna så kan den finare sanden (d = 0,15-0,5 mm) inte rekommenderas då den inteklarade en ytbelastning av 0,2 m/h.Med hänvisning till dessa resultat utesluts perkolationsfilter som en tänkbar lösning i Hassela. skillnaden i uppstarten var dock i det närmaste obefintlig så i detta fall verkar användning avsand belagd med brunsten ej motiverat. När ytbelastningen ökades påverkades intereningsresultatet. Även reduktionen av järnhalten var tillräcklig trots att vattnet inte luftadesinnan det tillfördes filtret.Ett perkolationsfilter skulle kunna fungera bra i Munkbysjön, men ytterligare försök med t.ex.ännu högre ytbelastning och/eller grövre sand skulle kunna testas.

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The main objective of the thesis was to evaluate the potential of selected Mn and Fe (nano)oxides for the stabilization of metals and metalloids in contaminated soils. The research was focused basically on three materials - commercial nanomaghemite (Fe III), nanomagnetite (Fe II,III) and a synthetic amorphous Mn oxide (AMO). The main aim of the work was to provide a complex view on the chosen stabilizing amendments regarding not just their direct influence on contaminants mobility and stabilization mechanisms, but also their stability and alterations in soil conditions together with influence on soil microorganisms and higher plants. Firstly, adsorption properties of the tested materials towards Cd, Cu, Pb and As were investigated. In this context, the most effective material showed to be the AMO reaching one to two orders of magnitude higher adsorption capacities than Fe III and Fe II,III under given experimental conditions. Interestingly, the rate of As(V) adsorption onto AMO was increasing with increasing pH as a result of high pHzpc of the AMO (8.1) and significant dissolution of this phase at lower pH values. As a next step, the influence of (nano)oxides on metal(loid)s mobility and other physico-chemical soil characteristics after application to contaminated soil was examined. Again, the AMO proved to be the most efficient in reducing mobile pools of Cd, Cu, Pb, Zn and As. On the other hand, Fe III and Fe II,III addition had generally less significant effects on contaminants mobility. AMO application further resulted in an increase of soil pH connected with AMO dissolution and unwanted decomposition of soil organic matter. When (nano)oxides alterations in soil conditions were observed, MnCO3 coatings were identified on AMO surface while no significant changes were recorded for Fe III and Fe II,III. As the MnCO3 formation was connected with increased AMO stability, AMO particles synthetically covered with MnCO3 coating (denoted as SM AMO) were prepared. Although the SM-AMO had a lower mass loss in soil than pure AMO, the stabilizing efficiency was almost the same for both materials. The differences in surface composition of both materials were decreasing with time as MnCO3 naturally precipitated on the AMO surface in soils while the SM AMO coating was gradually dissolving. When investigating the effect on soil microbiota, AMO efficiently promoted soil microbial activity while no significant changes were observed in the case of Fe III and Fe II,III. The AMO was also able to reduce the uptake of Cd, Pb and Zn by sunflower (Helianthus annuus L.), eliminate Zn phytotoxicity symptoms and increase biomass yield. On the other hand, toxic levels of Mn released from the AMO in an acidic soil were found in sunflower tissues. AMO application is thus recommended for contaminated neutral or slightly alkaline pH with a higher cation exchange capacity in order to avoid unwanted release of Mn. Finally, various types of AMO-biochar composite sorbents were recently prepared and field experiment focused on stabilization of Cd, Pb, Zn and As using studied materials is currently under preparation. The combined results from the thesis highlight the importance of a complex experimental approach dealing with all parts of the contaminated soil environment in order to obtain complete information about the efficiency and usefulness of any newly developed stabilizing amendment.

The PhD thesis presents the study on magnetic, paramagnetic resonance spectra, broadband dielectric spectroscopy, optical in the UV-vis-NIR combined with the determination of an energy gap as well as measurements of electrical conductivity and thermoelectric power versus a function of temperature and current-voltage characteristics I-V including conductance as a function of voltage curried out for following tungstates RE2W2O9 (RE = Pr, Sm-Gd), MRE2W2O10 (M = Cd, Co, Mn; RE = Y, Pr, Nd, Sm - Ho), AgY1-xGdx(WO4)2 (0,005  x  1), AgY1-xNdx(WO4)2 (0,005  x  1) CuSm2W2O10, Cu3Sm2W4O18, CoEu4W3O16 and for Cd1-3xGd2xxMoO4 molybdates (0,0005  x  0,2222). Detailed measurements of magnetic susceptibility, magnetic isotherms and paramagnetic resonance spectra for AgY1-xGdx(WO4)2 (0.005  x  1) revealed the nature of the paramagnetic spin visible in the Landé factor (g  2), estimated both from the Curie constant and the Brillouin procedure. Based on UV-vis-NIR measurements, the values of the energy gap ranging from 2.4 eV to 3.73 for MPr2W2O10 (M = Cd, Co i Mn) and RE2W2O9 (RE = Pr, Sm-Gd) as well as for Cd1-3xGd2xxMoO4 molybdates (x = 0,0, 0,0238 i 0,1667) were determined. These values are typical for insulators, for which electrons cannot be activated only by means of thermal energy kT. Relative dielectric constant and loss tangent measurements for CuSm2W2O10, Cu3Sm2W4O18, CoEu4W3O16 and RE2W2O9 (RE = Pr, Sm-Gd) suggest that only those ions that have a large number of unpaired electrons on unscreened orbitals are responsible for the colossal dielectric effect as it takes place for CoEu4W3O16. Measurements of electrical conductivity and thermoelectric power for RE2W2O9 (RE = Pr, Sm-Gd), MRE2W2O10 (M = Cd, Co, Mn; RE = Y, Pr, Nd, Sm - Ho), AgY1-xGdx(WO4)2 (0,005  x  1) i AgY1-xNdx(WO4)2 (0,005  x  1) as well as for Cd1-3xGd2xxMoO4 (0,0005  x  0,2222) revealed mostly poor electrical conductivity of n-type defects associated with the dominance of anionic acting as double donors. For some tungstates and molybdates, such as MPr2W2O10 (M = Co, Mn) of unfilled and unscreened 3d orbital of transition metals, a significant increase of the electron emission and the conductance of about two orders of magnitude of 300 K and about three orders of magnitude of 400 K were observed. Similar behavior was found for Cd1-3xGd2xxMoO4 solution in the concentration range of 0.0238  x  0.0839 and a strong emission of electrons at 400 K on the current-voltage characteristics I-V was observed. Measurements of current-voltage characteristics I-V are an excellent tool for studying electron emission materials weakly conductive. They also found that a strong electron emission does not depend on the value of the energy gap. Small electrical conductivity and low emission of electrons were explained with the aid of the deep vacancy trapping centers associated with high energy of creation of silver vacancy of 1.10 eV/ vac. in AgY1 x(Gd,Nd)x(WO4)2. High electrical conductivity and strong emission of electrons for MPr2W2O10 (M = Co, Mn) containing ions that have unfilled and unscreened orbitals explained using the Poole-Frenkel model by the emission of electrons over the potential barrier. High electrical conductivity and strong emission of electrons for Cd1-3xGd2x xMoO4 (0.0238 ≤ x ≤ 0.0839) containing ions, which are paired electrons, completed and screened orbitals explained through the mechanism of small polarons. Optical studies for tungstates and molybdates which have a strong emission of white and red light, and suitable for the production of ceramic matrix laser also exhibit strong electron emission visible in the current-voltage characteristics I-V. These results have been published in the international journals as Materials Science and Engineering: B, Ceramics International i Journal of the European Ceramic Society and presented at many national Polish and international conferences.

Prisusutvo  arsena  u  podzemnim  vodama,  koje  se  primenjuju  za vodosnabdevanje stanovništva je globalan problem. Različiti  konvencionalniprocesi  se primenjuju  za  uklanjanje  arsena iz vode, uključujući koagulaciju iflokulaciju,  sorpciju,  membransku  filtraciju  i  jonsku  izmenu.  Uzimajući  uobzir relativnu nisku cenu, jednostavnu kontrolu procesa i održavanje, visokstepen uklanjanja arsena, sorpcija se smatra jednom od najpodobnijih tehnikaza uklanjanje arsena u tretmanu vode za piće. Premda su na tržištu dostupnirazličiti  sorbenti  za  uklanjanje  arsena,  postoji  potreba  za  iznalaženjem  irazvojem  novih  low-cost  sorbenata,  a  kojima  bi  se  pak  mogao  obezbeditivisok stepen uklanjanja oba oksidaciona oblika  arsena,  i  As(III) i As(V). Ciljovog rada bio je usmeren na sintezu i karakterizaciju novih sorbenata na bazigvožđa  i  mangana  odnosno  Fe-Mn  binarnog  oksida,  ispitivanje  njihovogpotencijala  za  uklanjanje  arsena  iz  vode  i  utvrđivanje  da  li  novosintetisanisorbenti po pitanju efikasnosti, mogu konkurisati postojećim komercijalnim iširoko korišćenim sorbentima u tretmanima voda.Metodom  precipitacije,  sintetisani  su  Fe-Mn  binarni  oksidi  sa  različitim Fe:Mn  molskim  odnosima  1:1,  3:1,  6:1  i  9:1,  dok  su  kombinacijom heterogene  nukleacione  tehnike  i  precipitacije,  sintetisana  i  četiri  sorbenta magnetnih  svojstava  (Mag,  Mag-Fe,  Mag-Mn,  Mag-FeMn).  Modifikacijom biopolimera  Chitosana  i  GAC,  sa  Fe-Mn  binarnim  oksidom,  razvijena  su preostala  dva  materijala  Chit-FeMn,  odnosno  GAC-FeMn.  Sintetisani sorbenti su karakterisani različitim tehnikama i metodama (SEM/EDS, XRD,FTIR, BET).Fizičko-hemijskom karakterizacijom sintetisanih sorbenata ustanovljeno je da se Fe-Mn binarni oksidi i magnetni materijali, karakterišu relativno velikim specifičnim  površinama  (109-300  m ² /g)  i  zapreminama  mezopora (0,144-0,403  cm ³ /g).  Velika  specifična  površina  i  razvijena  mikroporozna struktura uočena je kod GAC-FeMn (996 m² /g; 0,394 cm ^{3 /}g). U poređenju sa ostalim  sintetisanim  sorbentima,  Chit-FeMn  je  karakterisala  najmanja specifična  površina  i  zapremina  mezopora  (1,99  m² /g;  0,014  cm ³ /g).  XRD analiza  Fe-Mn  binarnih  oksida  ukazala  je  da  je  fazna  struktura  sintetisanih Fe-Mn  binarnih  oksida  slična  ferihidratu  dok  je  fazna  struktura  magnetnih materijala ukazala na prisustvo magemita.Ispitivanja kinetike sorpcionog procesa ukazala su da je mehanizam sorpcijeAs(III)  i  As(V)  na  sintetisanim  sorbentima  sloţena  kombinacija  površinskehemisorpcije,  koja  se  odvija  kroz  granični  sloj  čestica  sorbenata  i unutarčestične difuzije. Tome u prilog išli su i rezultati FTIR analize kojimaje potvrđeno da se sorpcija arsena na sintetisanim sorbentima ostvaruje krozinterakcije hidroksilnih grupa gvožđa prisutnih na površini sorbenata i arsena.Dodatno, pokazano je da se za razliku od sorpcije As(V), sorpcija As(III) na sorbentima  koji  pored  oksida  gvožđa  sadrže  i  okside  mangana  (Fe-Mn binarni oksidi, Mag-FeMn, Mag-Mn,Chit-FeMn i GAC-FeMn) odvija u dva koraka. U prvom koraku As(III) se oksiduje do As(V), dok u drugom koraku, oksidovani  As(V)  mehanizmom  ligandne  izmene  formira  komplekse  na površini ovih sorbenata.Afiniteti sorpcije Fe-Mn binarnih oksida (na osnovu K_d vrednosti)  za As(III) opadali su u nizu Fe-Mn 3:1 > Fe-Mn 1:1 > Fe-Mn 6:1 > Fe-Mn 9:1 odnosno kod  As(V):  Fe-Mn  6:1  >  Fe-Mn  3:1  >  Fe-Mn  9:1  >  Fe-Mn  1:1.  Kod magnetnih kompozita,  najveća K_d vrednost za As(III) i As(V) ustanovljena je kod  Mag-FeMn.  Uopšteno,  Kdvrednosti  za  As(III),  kod  magnetnih kompozita,  opadale  su  u  nizu:  Mag-FeMn  >  Mag-Mn  >  Mag  >  Mag-Fe, Slično, afinitet sorbenata za As(V), opadao je na sledeći način: Mag-FeMn > Mag  >  Mag-Fe  >  Mag-Mn.  U  poređenju  sa  neimpregniranim,  K_d vrednosti bile su daleko veće kod obloţenih materijala, Chit-FeMn i GAC-FeMn, što je ukazalo  na  značajan  doprinos  Fe-Mn  binarnog  oksida  adsorpcionom kapacitetu neimpregniranih medija za As(III) i As(V). U  odnosu  na  ostale  ispitivane  anjone,  najveći  uticaj  na  sorpciju  oba  oblika arsena  na  svim  sintetisanim  sorbentima  uočen  je  kod  fosfata,  dok  je  uticaj nitrata i hlorida, u svim slučajevima bio bez značaja. Uticaj ispitivanih anjona na  sorpciju  As(III)  i  As(V)  na  Fe-Mn  binarnim  oksidima,  magnetnim materijalima, Chit-FeMn kao i na sorpciju As(V) na GAC-FeMn, opadao je u nizu: fosfati > silikati > karbonati > sulfati > nitrati > hloridi. Slično, uticaj ispitivanih  anjona  na  sorpciju  As(III)  na  GAC-FeMn  je  opadao  na  sledeći način: fosfati > silikati > sulfati > karbonati > nitrati > hloridi.Primenom  smeše  NaCl-NaOH-NaOCl  odnosno  primenom  0,1  M  i  0,5  M  rastvora NaOH, ustanovljeno je da se sintetisani sorbenti mogu jednostavno i  efikasno  regenerisati  i  višestruko  primeniti,  što  je  od  izuzetnog  značaja  sa ekološkog i ekonomskog aspekta.  Najmanje smanjenje sorpcionog kapaciteta  i za As(III) i za As(V), nakon pet ciklusa sorpcije -desorpcije, ustanovljeno je kod binarnog oksida sa Fe:Mn molskim odnosom 3:1 i Mag-FeMn.  Na osnovu rezultata prikazanih u ovom radu, može se zaključiti da sintetisani sorbenti,  Fe-Mn  binarni  oksidi  i  magnetni  kompoziti,  posebno  Mag-FeMn, mogu  biti  efikasna  i  ekonomična  alternativa  skupim  komercijalnim sorbentima  i  drugim  sofisticiranim  tehnologijama.  Visok  oksidacioni  i sorpcioni kapacitet ovih  materijala, koji obezbeđuje istovremeno uklanjanje  oba oksidaciona oblika arsena daje veliku prednost ovim sorbentima i čini ih veoma  atraktivnim  i  obećavajućim  u  tretmanu  voda.  Dodatni  benefitmagnetnih  sorbenata,  pre  svega  Mag-FeMn,  ogleda  se  u  njegovoj jednostavnoj separaciji iz vodenog medijuma i recirkulaciji u sistemu. Glavne prednosti  sintetisanih  Chit-FeMn  i  GAC-FeMn,  ogledaju  se  u  mogućnosti  njihove primene kao efikasne filtracione ispune.
The  presence  of  inorganic  arsenic  in  groundwater  used  for  drinking  water supply  is  a  global  problem.  Different  techniques  such  as  oxidation, coagulation,  adsorption,  ion  exchange,  and  membrane  filtration  have  been developed  and  applied  for  arsenic  removal  from  aqueous  media.  Among these  technologies,   adsorption  is  regarded  as  one  of  the  most  promising approaches to remove arsenic from water because of its high efficiency, low cost, simplicity of operation. Although many sorbents for arsenic removal are available on the market, there is still a need to identify and develop new  lowcost  sorbents which are highly effective in removing both oxidation states of arsenic, As(III) and As(V). This dissertation therefore presents the synthesis and  characterization  of  ten  new  iron  and  manganese  based  sorbents specifically developed for effective As removal. The Fe- Mn binary oxides were prepared with Fe:Mn molar ratios of 1:1, 3:1,6:1 and 9:1, while four heterogeneous magnetic composites (Mag, Mag-Fe,Mag-Mn,  Mag-FeMn)  were  synthesized  by  combining  the  heterogeneous nucleation  technique  with  precipitation.  The  remaining  two  materials, Chit-FeMn  and  GAC-FeMn,  were  created  by  modifying  the  Chitosan  and GAC  biopolymers  with  Fe-Mn  binary   oxide  (Chit-FeMn  and  GAC-FeMn).Multiple  techniques  were  applied  to  determine  the  physical  and  chemical characteristics  of  the  resulting  sorbents  (including  SEM/EDS,  XRD,  FTIR and BET analyses). In order to establish which sorbents show  the greatest promise for application during  drinking  water  treatment,  the  sorption  capacity  of  the  sorbents,  theAs(III)  and  As(V)  sorption  mechanisms,  and  the  impact  of  various  factors relevant to arsenic sorption, including the regeneration potential and the reuse potential of the sorbents, were all investigated in  batch experiments. During the physical characterisation, the Fe-Mn binary oxides and magnetic materials  were  found  to  have  relatively  large  specific  surface  areas (109-300 m 2 /g) and mesopore volumes (0.144-0.403 cm 3 /g).  A large specific surface  area  and  microporous  structure  was  observed  for  GAC-FeMn  (996 m 2 /g;  0.394  cm 3 /g).  In  comparison  with  the  other  synthesized  sorbents,  Chit-FeMn has the smallest specific surface area and pore volume (1.99 m 2 /g; 0.014  cm 3 /g).  XRD  analyses  of  the  Fe-Mn  binary  oxides  indicated  that  the phase  structure  of  the  synthesized  Fe-Mn  binary  oxides  was  similar  to ferrihydrate,  while  the  phase  structure  of  the  magnetic  materials  showed  a good agreement with the XRD diffractogram of maghemite. Investigations into As sorption process kinetics have shown that the sorption mechanism  for  both  As(III)  and  As(V)  on  the  synthesized  sorbents  is  a combination  of  surface  hemisorption,  which  takes  place  through  the boundary  layer  of  sorbent  particles,  and  intracellular  diffusion.  The  FTIR analyses  confirmed  that  arsenic  sorption  was  accomplished  through  the interactions  of  the  hydroxyl  groups  of  iron  present  on  the  surface  of  the sorbents and arsenic. In contrast to the sorption of As(V), it was also shown that  As(III)  sorption  onto  sorbents  containing  manganese  oxides  (Fe-Mn binary  oxides,  Mag-FeMn,  Mag-Mn,  Chit-FeMn  and  GAC  -FeMn)  takes place in two steps. In the first step As(III) is oxidized to As(V), while in the second  step,  the  oxidized  As(V)  forms  complexes  on  the  surface  of  the sorbents via ligand exchange. The  Fe-Mn  binary  oxide  sorption  capacities  (expressed  as  Kd values)  for As(III)   followed the trend Fe-Mn 3:1 > Fe-Mn 1:1 > Fe-Mn 6:1 > Fe-Mn 9:1, whereas the  As(V) trend was Fe-Mn 6:1 > Fe-Mn 3:1 > Fe-Mn 9:1 > Fe-Mn 1:1. In the magnetic  composites, the largest  Kd value for As(III) and As(V) was  obtained  for  Mag-FeMn.  Generally,  the  Kd values  for  As(III)  in  the magnetic composites decreased in the series: Mag-FeMn > Mag-Mn > Mag > Mag-Fe.  Similarly,  the  affinity  of  the  sorbents  for  As(V)  was  as  follows: Mag-FeMn  >  Mag  >  Mag-Fe  >  Mag- Mn.  In  comparison  to  the  nonimpregnated  materials,  the  Kd values  were  much  higher  for  the   boated materials,  Chit-FeMn  and  GAC-FeMn,  demonstrating  the  significant advantage  Fe-Mn  binary  oxides  provide  in  increasing  As(III)  and  As(V)  adsorption capacities. One  of  the  most  problematic  limiting  factors  in  applying  adsorption technologies during drinking water treatment is the presence of other water constituents which interfere with the adsorption process.  Investigations into the inhibitory effect of competive anions on the adsorption of both forms of arsenic  revealed  that  phosphates  were  the  worst  offenders  in  terms  ofreducing  the  arsenic  removal  efficacy  of  sorbents  investigated.  From  the largest  to  the  smallest  negative  influence  of  the  anions  investigated,  for As(III)  and  As(V)  adsorption  on  Fe-Mn  binary  oxides,  magnetic  materials and Chit-FeMn, as well as As(V) adsorption on GAC-FeMn, the order was: phosphates > silicates > carbonates > sulfates > nitrates > chlorides, with the presence  of  the  latter  two  anions  proving  almost  irrelevant  to  the  As adsorption  process.  Similarly,  the  negative  influence  of  anions  on  As(III) sorption on GAC-FeMn was: phosphates > silicates > sulphates > carbonates > nitrates > chlorides. Another  issue  with  applying  adsorption  in  real  treatment  conditions  is  the need to regularly  regenerate and/or replace the spent sorbent. In this work, a simple  and  efficient  process  for  sorbent   rfegeneration  is  demonstrated.  This regeneration  process  can  be  applied  to  the  sorbents  investigated  multiple times, and uses an NaCl-NaOH-NaOCl mixture, or 0.1 M and 0.5 M NaOH solutions.  This  finding  is  of  great  importance  from  an  ecological  and economic point of view. The minimum reduction in the sorption capacity for both As(III) and As(V), after five sorption-regeneration cycles, was found in  the  binary  oxide  with  a  3:1  Fe:Mn  molar  ratio  and  Mag-FeMn.  Arsenic sorption  behaviour  was  also  investigated  using  real  groundwater  samples, with the results demonstrating the great potential of 3:1 Fe-Mn binary oxide and Mag- FeMn. However, Chit-FeMn and GAC-FeMn were less effective at adsorbing As from the groundwater samples.Based on the results presented in this dissertation, it can  be concluded that the synthesized  sorbents,  especially  the  Fe-Mn  binary  oxides  and  magnetic composites,  and  Mag-FeMn  in  particular,  can  be  efficient  and  economical alternatives  to  expensive  commercial  sorbents  and  other  sophisticated  As removal  technologies.  The  high  oxidation  and  sorption  capacity   of  these materials,  which  ensure  the  simultaneous  removal  of  arsenic  with  both oxidation states, is a large advantage for these sorbents and makes them very attractive  and  promising  for  application  in  drinking  water  treatment.  An additional  benefit of the magnetic sorbents, primarily Mag-FeMn, is the ease with  which  they  may  be  separated  from  the  aqueous  medium,  allowing  for simple  recirculation within a system. Similarly,  the main advantages of  the synthesized Chit- FeMn and GAC-FeMn are reflected in their application as effective filtration media.

Ziel der vorliegenden Arbeit war es zum einen, das Potential von chiralen Eisenporphyrin- und Mangansalen-Katalysatoren zur kinetischen Racematspaltung sekundärer Allylalkohole durch asymmetrische Epoxidierung auszuloten. Zum anderen sollten Untersuchungen zum Mechanismus der Jacobsen-Katsuki-Epoxidierung durchgeführt werden; ein besonderes Augenmerk lag dabei auf der Fragestellung, welche Faktoren dazu führen, dass bei der Umsetzung von cis-Olefinen ein Gemisch aus cis- und trans-Epoxiden erhalten wird. Eine Auswahl arylsubstituierter Allylalkohole IIa-f wurde mit den Katalysatoren Ia und Ib,c und 0.8 bzw. 0.6 Äquivalenten an Iodosobenzol als Sauerstoffdonor umgesetzt (Gl. I), wobei es zu einer kinetischen Racematspaltung kommt. Die Oxidation verläuft für beide Katalysatorsysteme sowohl chemoselektiv (vorwiegend Epoxidierung) als auch diastereoselektiv (dr bis zu > 95:5). Als Hauptprodukte werden für die offenkettigen Allylalkohole IIa,e,f die threo-konfigurierten Epoxyalkohole III erhalten, während die cyclischen Allylakohole IIb-d die entsprechenden cis-Epoxyalkohole III lieferen. 1,1-Dimethyl-1,2-dihydro-2-naphthol (IIc) ist hierbei eine Ausnahme, da die CH-Oxidation dieses Substrats eine beachtliche Nebenreaktion darstellt. Der Hauptunterschied zwischen den Fe- und Mn-Katalysatoren liegt in der Enantioselektivität: Während mit dem Fe(porph*)-Komplex Ia nur Selektivitäten von maximal 43 Prozent ee (krel = 2.7) erzielt werden, erwiesen sich die Mn(salen*)-Komplexe Ib,c als geeignete Katalysatoren, mit denen ee-Werte von bis zu 80 Prozent (krel = 12.9) erreicht werden. Die in der kinetischen Racematspaltung erzielten Selektivitäten können durch ein synergistisches Zusammenwirken von hydroxy-dirigierendem Effekt einerseits und sterischen Wechselwirkungen zwischen Substrat und Eisen-Komplex oder, im Falle des Mangan-Komplexes, Angriff des Olefins entlang der so genannten Katsuki-Trajektorie andererseits erklärt werden. Fazit: Die chiralen Mn(salen*)-Komplexe Ib,c sind wirkungsvolle Katalysatoren für die asymmetrische Epoxidierung racemischer sekundärer Allylalkohole II. In exzellenten Chemo- und Diastereoselektivitäten entstehen die entsprechenden Epoxyalkohole III mit ee-Werten bis zu 80 Prozent. Die zurückbleibenden Allylalkohole werden dabei bis zu 53 Prozent ee angereichert. Im Vergleich dazu weist der Eisenkomplex Ia eine ungleich geringere Enantioselektivität auf. Mechanistische Untersuchungen mit Vinylcyclopropan Va ergeben, dass die Jacobsen-Katsuki-Epoxidierung nicht über ein kationisches, sondern über ein radikalisches Intermediat abläuft. Dies wird anhand von Produktstudien durch reversed phase-HPLC-Analytik belegt. In weitergehenden Untersuchungen mit cis-Stilben (Vb) und cis--Methylstyrol (Vc) als Sonden zur cis/trans-Isomerisierung wurde festgestellt, dass die Diastereoselektivität der Epoxidierung nicht nur vom Gegenion des Mangankatalysators Ib, sondern auch von der eingesetzten Sauerstoffquelle [OxD] abhängt. Daher musste der Katalysezyklus (Schema A) um eine diastereoselektivitäts-bestimmende Gabelung erweitert werden: Das primär entstehende MnIII(OxD)-Addukt kann entweder unter Abspaltung der Fluchtgruppe zum etablierten MnV(oxo)-Komplex reagieren (Weg 1) oder direkt das Olefin epoxidieren (Weg 2). Während die Sauerstoffübertragung durch die Oxo-Spezies stufenweise über ein Radikalintermediat verläuft und damit zu einer Mischung aus cis- und trans-Epoxid führt, erfolgt der Lewisäure-aktivierte Sauerstofftransfer konzertiert. Der Gegenion-Effekt auf die cis/trans-Isomerisierung erklärt sich dahingehend, dass die Natur des Anions (koordinierend oder nicht-koordinierend) die Lebensdauer des Radikalintermediats und/oder die Lage und Selektivität der Energiehyperflächen der verschiedenen Spinzustände des MnV(oxo)-Oxidans beeinflusst. Fazit: In der Jacobsen-Katsuki-Epoxidierung existiert neben dem etablierten MnV(oxo)-Oxidans zumindest noch ein weiteres; dabei handelt es sich um das MnIII(OxD)-Addukt, dessen Sauerstoff Lewissäure-aktiviert übertragen wird. Ein unterschiedlicher Anteil der beiden Reaktionskanäle erklärt die Unterschiede im Ausmaß der cis/trans-Isomerisierung. Auch das Gegenion des Mangan-Komplexes Ib beeinflusst die cis/trans-Diastereoselektivität. Mit koordinierenden Gegenionen dominiert Isomerisierung zum trans-Epoxid, während nicht-koordinierende Gegenionen bevorzugt zum cis-Epoxid führen
The aim of the present work was to explore the potential of chiral iron(porphyrin) and manganese(salen) complexes for the kinetic resolution of secondary allylic alcohols by asymmetric epoxidation. Furthermore, the mechanism of the Jacobsen-Katsuki epoxidation was investigated by elucidating the factors that determine the cis/trans diastereoselectivity in the epoxidation of cis olefins. A set of aryl-substituted racemic allylic alcohols IIa-f has been oxidized by the catalysts Ia and Ib,c with 0.8 or 0.6 equiv. of iodosyl benzene as oxygen source (eq. I) to effect kinetic resolution. For both catalysts, the oxidation is chemoselective (predominantly epoxidation) as well as diastereoselective (dr up to > 95:5), to afford the threo- or cis-configured epoxy alcohols III as main products. In this kinetic resolution, one enantiomer of the allylic alcohol II is preferentially epoxidized to give the corresponding epoxy alcohol III in ee values up to 80 per cent, the other enantiomer remains unreacted and is enriched (up to 53 per cent ee). Quite exceptional is 1,1-dimethyl-1,2-dihydro-2-naphthol (IIc), for which the CH oxidation dominates. The main difference between the iron and the manganese catalysts concerns their enantioselectivity: Whereas the Fe(porph*) complex Ia exhibits only moderate ee values of up to 43 per cent (krel up to 2.7), the Mn(salen*) complexes Ib,c provide enantioselectivities of up to 80 per cent ee (krel up to 12.9), which makes them useful catalysts for the kinetic resolution of the allylic alcohols II. The appreciable selectivities displayed for the manganese complexes Ib,c in these asymmetric epoxidations may be rationalized in terms of the synergistic interplay between the hydroxy-directing effect and the interactions of the catalyst and the substrate in the attack of the olefin along the Katsuki trajectory. Conclusion: The chiral Mn(salen*) complexes Ib,c are highly effective catalysts for the asymmetric epoxidation of the racemic allylic alcohols II. The respective epoxy alcohols III are formed in excellent chemo- and diastereoselectivitites with ee values up to 80 per cent, while the unreacted allylic alcohols are enriched up to 53 per cent ee. In comparison, the enantioselectivity for the iron catalyst Ia is much lower. The manganese-catalyzed oxidation of vinylcyclopropane Va reveals that radical intermediates are formed in the Jacobsen-Katsuki epoxidation rather than cationic ones, as has been confirmed through product studies by reversed-phase HPLC analysis. With cis-stilbene (Vb) and cis--methyl styrene (Vc) as mechanistic probes, it has been shown that the cis/trans diastereoselectivity of the Mn(salen)-catalyzed epoxidation depends not only on the counterion of the catalyst Ib, but also on the oxygen donor [OxD]. A diastereoselectivity-controlling bifurcation step needs to be added to the catalytic cycle (Scheme A), in which the initial MnIII(OxD) adduct may either split off its leaving group to form the established MnV(oxo) species (path 1) or epoxidize the olefin directly (path 2). The oxygen transfer by the oxo complex occurs stepwise through a radical intermediate and results in a mixture of the cis and trans epoxides; in contrast, the Lewis-acid-activated epoxidation is concerted. The effect of the counterion on the cis/trans diastereoselectivity may be explained in terms of whether the anion ligates to the metal. This affects the lifetime of the radical intermediate and/or the reaction profiles of the singlet, triplet and quintet spin states of the MnV(oxo) species, which in turn control the stereoselectivity. Conclusion: In addition to the established MnV(oxo) oxidant, at least one other oxidant has to be involved in the Jacobsen-Katsuki epoxidation; this species is proposed to be the MnIII(OxD) adduct that transfers its oxygen atom in a Lewis-acid activation. Varying proportions of the two oxygen-transfer pathways account for the cis/trans diastereoselectivities observed with the various oxygen donors. The cis/trans ratio also depends on the counterion of the manganese catalyst Ib: Whereas ligating counterions result in extensive cis/trans isomerization, with non-ligating counterions the formation of cis epoxides is strongly favored