Membrane-based gas separation processes are an area of interest owing to their high industrial demand for a wide range of applications, such as natural gas purification from CO2 or H2, and N2 or O2 separation from air. This thesis is focused on developing and investigating polymeric-based membranes. Firstly, novel mixed matrix membranes (MMMs) were prepared, incorporating few-layer graphene in the polymer of intrinsic microporosity PIM-1. Secondly, novel polyphenylene-based polymers of intrinsic microporosity (PP-PIMs) were synthesised. An optimum preparation method of graphene/PIM-1 MMMs (GPMMMs) was established from numbers of experiments. In this study, graphene exfoliation was a step towards GPMMM preparation. Starting from graphene exfoliation in chloroform, as a good solvent for PIM-1, enhancement in graphene dispersibility was obtained with addition of PIM-1. This result helped in GPMMM preparation with high graphene content (up to 4 wt.%). Characterizations techniques such as Raman spectroscopy and scanning electron microscopy (SEM) of GPMMMs, confirmed the few layer graphene content, with morphology changes in the polymeric matrix compared to pure PIM-1.Gas permeability results of GPMMMs showed an enhancement in permeability with low loading graphene (0.1 wt.%) using a relatively low permeability PIM-1 batch, due to high water content. However, less influence of graphene incorporation on permeability was observed with a highly permeable PIM-1 batch. Reduction in permeability over time, termed an ageing effect, is known for a polymer of high-free volume like PIM-1. However, the enhancement of GPMMMs permeability after eight months storage was shown to be retained. Novel PP-PIMs were prepared from novel precursors using a series known organic reactions. PP-PIMs were divided into two groups of polymers based on their polymerization reactions. A group of polymers were prepared from condensation polymerization between bis-catecol monomers and tetrafluoroterephthalonitrile (TFTPN). Another group of polymers were prepared from Diels Alder polymerization between monomers of terminal bisphenylacetylene groups and bis tetraphenylcyclopentadienones (TPCPDs). All of which yielded polymers with apparent BET surface area in the range 290-443 m2 g-1.

Kyoto University (京都大学) / 0048 / 新制・課程博士 / 博士(工学) / 甲第14624号 / 工博第3092号 / 新制||工||1460(附属図書館) / 26976 / UT51-2009-D336 / 京都大学大学院工学研究科電気工学専攻 / (主査)教授 引原 隆士, 教授 北野 正雄, 准教授 山田 啓文 / 学位規則第4条第1項該当

Magister Commercii (Industrial Psychology) - MCom(IPS) / The purpose of the study was to investigate the relationship between self-efficacy, goal-setting and achievement motivation among students in their final year at a selected university in the Western Cape Province. The sample consisted of 128 final year students who were asked to complete a questionnaire. The questionnaires comprise a section on the biographical information of the participants as well as sections containing the, Academic Self-Efficacy Scale, Achievement Motivation Scale and a Goal Setting Questionnaire. Informed consent was obtained from the various participants and anonymity of participation and confidentiality were ensured. Data was analysed using the Statistical Package for the Social Sciences (SPSS) version 23. The Statistical analyses techniques employed included Item Analysis, Pearson’s Correlation test, Factor Analysis and a Multiple Regression Analysis. The results of the study indicate there is a statistically significant relationship between selfefficacy and goal-setting (Hypothesis 1), self-efficacy and achievement motivation (Hypothesis 2), achievement motivation and goal-setting among students in their final year of study (Hypothesis 3). Furthermore the results indicated that self-efficacy and goal-setting are significant predictors of achievement motivation (Hypothesis 4). These findings indicate that the stronger an individual’s belief in their perceived self-efficacy, the more likely they are to set challenging goals for themselves which may in turn result in a stronger commitment to attaining those goals. In addition, students who are assured in their ability to achieve success in their studies are most likely to possess the need to achieve excellence. Furthermore, results suggest that students who possess the need to achieve excellence or demonstrate higher levels of achievement motivation have the tendency to set more challenging goals than those with lower levels of achievement motivation. / National Research Foundation

Magister Commercii - MCom / Job Satisfaction and the Intention to Quit are two factors that a synonymous with each other. Various research and studies have been conducted over the years indicting that there is a direct relationship between job satisfaction and intention to quit, suggesting that these factors often result in employees with low levels of job satisfaction resigning from the organisations they are employed at. Therefore the objective of this study was to examine those factors that affect job satisfaction and the intention to quit amongst employees at a small to medium auditing firm in South Africa. Demographic factors such as age, gender, marital status, tenure (length of service), number of dependents and qualification was used to establish the impact it had on employee's job satisfaction levels and their intention to quit. The study was conducted using a quantitative, non-probability, convenience sampling method. The sample group consisted of all permanent employees (N = 350) of an auditing firm with nine (9) offices across South Africa. The one hundred and fifteen (115) participants who voluntarily completed the questionnaires were made up of the CEO, Directors, Managers and employees within the Audit and Assurance, Accounting, Internal Auditing, Consulting and Group Services spectrum. They were required to complete an online biographical questionnaire (BQ), the Work Satisfaction and Motivation Questionnaire (WMQ) as well as the Michigan Organisational Assessment Questionnaire – Intention to Quit (ITQ), was used in order to gather relevant data for the study. Participants were informed that their participation was voluntary, anonymous and strictly confidential. All participants were informed of the purpose of the study and all ethical issues were clarified. Data was analysed by making use of the following data analysis techniques: descriptive, inferential, the Pearson product–moment correlation coefficient and ANOVA statistics. The results indicated that there was a significant positive relationship between job satisfaction and intention to quit amongst the sample of the auditing firms employees. There was also a significant relationship between pay and job satisfaction with a converse relationship between pay and intention to quit. Furthermore, the findings of the current study indicated that when taking into consideration the significant relationship between job satisfaction and intention to quit in relation to various biographic factors, there was no significant difference between different age groups, male or female, number of children (dependents) an employee had, their marital status or the qualifications that they held.However, it was found that there was no statistically significant difference between length of services and job satisfaction, but that there was a significant difference when taking into account the impact length of service had on the intention to quit. Recommendations were made and limitations for future research discussed in order to provide insight to the organisation stemming from the current study.

Stress fractures represent one of the most common and serious overuse injuries in the military environment. The aim of this prospective study was to determine the incidence of stress fractures during 12 weeks of Basic Training (BT) by comparing the results of the intrinsic risk indicators obtained from a group of participants who suffered stress fractures, with the rest of the original group (controls) who did not suffer from any stress fractures, and to assess any changes in physical markers whilst following a progressive, scientifically designed, Physical Training (PT) Programme during the BT. The intrinsic risk factors investigated included sex, age, race (measured via questionnaire), foot morphology (wet test), Q angle, leg length discrepancy, bone density (dual-energy X-ray absorptiometry(DEXA), physical fitness (standardized military fitness test, isokinetic upper and lower leg strength, handgrip strength), flexibility (ankle plantarflexion and dorsiflexion, hip internal and external rotation), anthropometry (skinfold method and DEXA), female menstrual disturbances and lifestyle behaviours including smoking, female contraception use and medical history of previous injury (questionnaire). The cohort (n=183), also refered to as the Experimental Group (EG), was measured at the beginning and at the end of the BT period. The standardized physical fitness test was also completed in the fifth week of training. The latter’s results were compared to the results obtained by a Control Group (CG), who had undergone BT the year prior to this cohort. The size of the cohort, the intrinsic risk factor profile and the control of certain extrinsic risk factors may have contributed to zero incidences of stress fractures found. Within the intrinsic risk factor profile, sex, age, race, foot morphology, Q angle, hip external rotation and bone density were normal whilst the measured leg discrepancy and limited ankle dorsiflexion appeared to not have a sufficient risk for stress fracture development. The small sample of the cohort that reported having menstrual irregularities, smoked and had a history of previous fractures, did not place this cohort at risk for stress fracture development. The cohort did, however have lower isotonic, isokinetic and isometric strengths than the other cohorts who reported a relatively high stress fracture incidence. The BT period found statistically significant changes in bone density, flexibility, body composition, muscle strength and endurance. Female participants showed an increase in the T- and Z-scores of the left femur area, a deterioration in left ankle dorsiflexion and hip external rotation, whilst their plantarflexion increased. Their mesomorph component increased, and decreases in % body fat (BF) as well as in the ectomorph and endomorph component were also found. Male participants’ plantarflexion and hip external rotation decreased whilst their dorsiflexion increased. Lean body mass and mesomorph component increased whilst %BF, ectomorph and endomorph component decreased. The new cyclic-progressive PT programme controlled for risk of injury by allowing sufficient periods of recovery, by gradually increasing the duration, frequency, and intensity of training, by reducing repetitive weight-bearing activities and by including a variation of exercises. Running shoes, rather than combat boots, were also worn during PT. Marching on concrete was eliminated. Significant improvements were shown by both male and female participants in aerobic fitness and muscular endurance and muscular strength. Future research should include a larger size cohort, who developed stress fractures utilising BT groups from different corps and units in the South African Military environment. Other potential extrinsic risk factors, such as surface and equipment, should also be investigated. / Thesis (DPhil)--University of Pretoria, 2009. / Biokinetics, Sport and Leisure Sciences / unrestricted

No description available.

Cadmium Telluride (CdTe) is a leading thin film photovoltaic (PV) material due to its near ideal bandgap of 1.45 eV and its high optical absorption coefficient. Advancements in efficiencies of CdTe/CdS solar cells over the past few decades have come from improving the short circuit current (JSC) and Fill Factor (FF) but the Open Circuit Voltage (VOC) has been stagnant. Further improvements in efficiencies should come from increased VOC’s. VOC’s can be improved by increasing the acceptor concentration and minority carrier lifetime. Both these parameters can be controlled by manipulating the native defect concentration in CdTe which can be achieved by varying CdTe stoichiometry. In this study, a deposition system called Elemental Vapor Transport was used to vary the CdTe stoichiometry with an intent to change the native defect concentration and therefore pave way to increase acceptor concentration and lifetimes. Elemental cadmium and tellurium were heated in dedicated zones and their vapors were transported to the substrate using a carrier gas. By varying the temperatures and flowrates of the carrier gas through the zones, the gas phase Cd/Te ratio was varied to deposit Cd-rich, Te-rich and stoichiometric films. Structural properties were investigated using Scanning Electron Microscopy (SEM), X-Ray Diffraction (XRD), and Transmission Electron Microscopy (EDS). Electrical characterization of completed devices was carried out by Current-Voltage (J-V), Capacitance-Voltage (C-V), and Spectral Response (SR) and Deep Level Transient Spectroscopy (DLTS) measurements. Cd-rich films showed smaller grain sizes and lesser degree of preferential orientation. Te-rich films showed increased acceptor concentration and carrier lifetimes and solar cells fabricated using these films showed higher VOC’s compared to Cd-rich and stoichiometric films .Higher degree of CdTe-CdS mixing was observed at the interface for films deposited at increased substrate temperatures.

The primary objective of this mini-dissertation was to investigate whether a relationship exists between rewards, intrinsic motivation, work engagement among school teachers in South Africa. A further aim was to determine if work engagement has a moderating effect on the relationship between rewards and intrinsic motivation. The researcher further investigated whether demographic differences occurred across the three constructs studied. The study made use of quantitative research to achieve the above-mentioned objectives. The researcher made use of Ulrechs Work Engagement Scales (UWES), Intrinsic Work Motivation Scale (IWMS) and the Organisational Rewards Scale (ORS) to measure the mentioned relationships. The ORS was qualitatively piloted on a sample of primary school teachers in a Non-governmental institution. After refinement, a composite questionnaire was electronically completed by 207 teachers within South Africa. Data analysis was conducted in the form of descriptive and inferential statistics, including Cronbach’s alpha testing, Pearson’s Product Moment Correlations, t-tests, analysis of variance and structural equation modelling. The quantitative findings suggested that rewards lead to higher levels of Work Engagement, which in turn causes higher levels of Intrinsic Motivation. Thus, there was full mediation of rewards onto intrinsic rewards through work engagement From a demographics perspective, practically significant differences were discovered between NGO’s and Government High Schools for Rewards. In addition to these results, age differences were discovered across Work Engagement and job level differences were discovered for Intrinsic Motivation, together with significant correlations between the three constructs. These results theoretically contribute to the validation of the newly developed Intrinsic Work Motivation Scale. Furthermore, the results make a valuable contribution to the field of rewards management for teachers in South Africa.

Human APOBEC3 proteins are host-encoded intrinsic restriction factors that can prevent the replication of a broad range of human and animal retroviruses such as HIV, SIV, FIV, MLVs and XMRV. The main pathway of the restriction is believed to occur as a result of the cytidine deaminase activity of these proteins that converts cytidines into uridines in single-stranded DNA retroviral replication intermediates. Uridines in these DNA intermediates disrupt the viral replication cycle and also alter retrovirus infectivity because of the C-to-T transition mutations generated as a result of the deaminase activity on the minus strand DNA. In addition, human APOBEC3 proteins also exhibit a deamination-independent pathway to restrict retroviruses that is not currently well understood. Although the restriction of retroviruses by human APOBEC3 proteins has been intensely studied in vitro, our understanding of how the murine APOBEC3 (mA3) protein restricts retroviruses and/or prevents zoonotic infections in vivo is very limited. In contrast to humans and primates that have 7 APOBEC3 genes, mice have but a single copy. My study of the function and structure of mA3 revealed that it has an inverted functional organization for cytidine deamination in comparison to the human A3G catalytic sites. I have also found that disruption of the integrity of either of these catalytic sites substantially impedes restriction of HIV and MLV. Interestingly, our data shows that mA3 induces a significant decrease in retroviral activity of HIV and MLVs by exploiting both deamination-dependent and -independent pathways. However, the deaminase activity of mA3 is essential to confer long-term restriction of retroviral infection. My observations suggest that mA3 has dual activities, both deamination-dependent and -independent, that work cooperatively to restrict a broad range of human and animal retroviral pathogens. In the context of the intrinsic immune system, APOBEC3 proteins provide a powerful block to the transmission of retroviral pathogens that very few have found ways to evade.

The thesis estimates the intrinsic value of share of the company Iveco Czech Republic, a.s. from the position of potential investor. The valuation is done through the DCF FCFE model. Prior to the financial plan and the valuation itself, the theses provides financial and strategic analysis of the company.