The field of soft electronics is rapidly growing as there is an increased demand for health monitoring using wearable electronics that conforms to biological tissue. To promote sustainability and reduce electronic waste, it is of interest to find ways to reuse low-value-added commodities, such as protein-rich byproducts, for materials in high-value-added technologies that are degradable at end of use. One recognised byproduct from meat production is the abundant protein collagen, or the hydrolysed derivative gelatine. To overcome the limited mechanical properties of gelatine, it can be functionalised with a polymer with previous use in tissue-engineering and battery encapsulation, namely Poly(Glycerol Sebacate)(PGS), to generate the copolymer PGS-G. The work described in this thesis focuses on PGS and PGS-G polymer characterisation by utilising ATR-FTIR and DSC, but also on material characterisation of mechanical and hydration properties, ionic conductivity, and degradation. The results indicate that the successfully synthesised PGS and PGS-G polymers should not be crosslinked completely to achieve the most flexible mechanical properties, but also that crosslinking density should be tuned to suit the application. Moreover, incorporation of gelatine in PGS resulted in increased hydrophilicity for PGS-G. Finally, it was concluded that PGS is suitable for encapsulation whereas PGS-G could be used as an active component. Future work should include degradation studies in vivo and under environmental aerobic conditions to ensure that the polymers are fully biodegradable. / Mjuk elektronik är ett nytt forskningsområde som utvecklas starkt i takt med den ökade efterfrågan på hälsoövervakning med innovativ elektronik som är mjuk och töjbar vilket möjliggör smidig integrering i biologisk vävnad. För att främja hållbarhet och minska elektroniskt avfall så är det av intresse att återanvända lågt värderade handelsvaror, såsom proteinrika restprodukter från industrin, till att skapa funktionella material för värdeskapande teknologier vilka är nedbrytbara efter användning. En välkänd restprodukt från köttproduktion är proteinet kollagen och dess hydrolyserade derivat gelatin. För att förbättra de mekaniska egenskaperna hos gelatin så kan det funktionaliseras med en polymer, vid namn Poly(Glycerol Sebacate)(PGS), som tidigare har använts för att skapa substitut till biologisk vävnad och batteriinkapsling. Denna reaktion genererar den nya polymeren PGS-G. I det här examensarbetet beskrivs karaktärisering av polymererna PGS och PGS-G, som utfördes med ATR-FTIR och DSC, samt karaktärisering av materialets mekaniska och hydrerande egenskaper men även dess ledningsförmåga och nedbrytbarhet. Resultaten indikerar att polymererna PGS och PGS-G ej bör tvärbindas fullständigt för att uppnå optimala mekaniska egenskaper med avseende på flexibilitet men också att tvärbindningen ska justeras beroende på tillämpningen. Vidare bidrar inkorporeringen av gelatin i PGS till en ökad hydrofilicitet i PGS-G. Slutligen visades det att PGS är lämpligt för inkapsling medan PGS-G kan användas som en aktiv komponent. Innan tillämpning behöver ytterligare studier genomföras med avseende på nedbrytbarhet, dels in vivo, dels i aerobiska förhållanden, för att säkerhetsställa att polymererna är fullständigt nedbrytbara.

Screen media activity such as watching TV and videos, playing video games, and using social media has become a popular leisure activity for children and adolescents. The effect of screen time has been a highly debated topic; however, there is still very little known about it. Using a dataset from the Adolescent Brain Cognitive Development longitudinal study 4 217 young adolescents, that met the requirements, could be retrieved for this thesis project after processing of the data. This thesis project investigated causal order between genetic effect (cognitive performance Polygenic scores (PGSs)), screen time activity, brain morphology (structural Magnetic Resonance Imaging (sMRI) for surface area and cortical thickness), lack of perseverance, and cognitive performance (crystallized IQ) with a machine learning algorithm DirectLiNGAM. A clear correlation between screen media activity and PGS was found for all types of screen time activities but only video games and social media correlated to the global surface area. Furthermore,  TV and video seem to affect lack of perseverance, and lack of perseverance, in turn, affects time spent on video games. These findings imply that different types of social media are not as alike as we thought and can affect adolescents differently. Taken together, these findings support previous research on screen media activity's effect on lack of perseverance, brain morphology, and cognitive performance, and propose new causal inference between genetics and screen time. Lastly, the algorithm used in this thesis project inferred reasonable causal orders and can be seen as a very good complement to today's causal modeling. / Skärmaktivitet som att titta på TV och video, spela videospel och använda sociala medier har blivit en populär fritidsaktivitet för barn och ungdomar. Effekten av skärmtid har varit ett mycket debatterat ämne; det finns dock fortfarande mycket lite kunskap om det. Med hjälp av datasetet från Adolescent Brain Cognitive Development långtidsstudien kunde 4 217 ungdomar, som uppfyllde specifika krav, väljas ut för detta avhandlingsprojekt efter bearbetning av datan. Detta avhandlingsprojekt undersökte kausal ordning mellan genetisk effekt (Polygenic scores (PGS) för kognitiv prestation), skärmtidsaktivitet, hjärnmorfologi (strukturell Magnet Resonans Imaging (sMRI) för hjärnans ytarea och hjärnbarks tjocklek), brist på ihärdighet och kognitiv förmåga (kristalliserad IQ) med en maskininlärningsalgoritm DirectLiNGAM. Tydlig korrelation mellan skärmaktivitet och PGS hittades för alla typer av skärmaktiviteter men endast videospel och sociala medier korrelerade till den globala ytarean. Dessutom verkar TV och video påverka brist på ihärdighet och brist på ihärdighet i sin tur påverkar hur mycket tid som spenderas på videospel. Dessa resultat antyder att olika typer av sociala medier inte är så lika som vi trodde och kan påverka ungdomar olika. Sammanlagt stöder dessa upptäckter tidigare forskning om skärmtidseffekt på brist på ihärdighet, hjärnmorfologi och kognitiv förmåga och föreslår en ny kausal inferens mellan genetik och skärmtid. Slutligen ledde algoritmen som användes i detta avhandlingsprojekt fram till rimliga kausala ordningar och kan ses som ett mycket bra komplement till dagens kausala modellering.

Introduction: In recent years, the average age of first reproduction has risen significantly, the mean now standing at around 30 years in many countries. The adverse effects of maternal age on fertility and reproduction have been well documented. However, the influence of paternal age on fertility, reproduction and postnatal health is relatively poorly understood, and 50% of all male infertility cases are classed as idiopathic or unexplained infertility. Methods: The aim of this study was to investigate factors that contribute to male infertility, split into two main parts. The first part focused on analysing data collected from patients who had undergone fertility treatment to assess the influence of different factors on infertility, especially at the genome level. The second part attempted to deal with some of the technical challenges of screening and diagnostic methods to study the genome, with the aim of providing tools that would assist future studies in pinpointing genetic factors responsible for infertility, especially in cases of idiopathic infertility. Results: Based on data from the first part of the study, it was determined that advanced paternal age can affect sperm progressive motility, sperm DNA integrity and the fertilisation rate of in vitro fertilisation (IVF) cycles, as well as the development of embryos. Direct analysis of sperm DNA fragmentation (SDF) and degradation levels revealed an association between elevated SDF and impaired embryo development. Furthermore, a correlation was shown between chromosome aneuploidy and variance in SDF and sperm DNA degradation. Moreover, aneuploidy can influence abnormal sperm morphology and consequently also progressive motility. Also, embryo development rate of IVF cycles on day three, demonstrated a significant decline in cycles where the sperm used for fertilisation had a high aneuploidy rate, which can highlight the reduced developmental capacity of aneuploid embryos. From the lifestyle factors assessed, only alcohol consumption significantly correlated with the sperm DNA damage. Therefore, poor semen quality may highlight damage that has been incurred by the sperm DNA. When the semen quality is suboptimal, the intracytoplasmic sperm injection (ICSI) technique is suggested as a standard strategy to improve the prognosis of ART. However, when the progressive motility is poor, the ICSI approach is not as effective. Based on our findings and in line with other studies, the only sperm parameter that can be affected by paternal age is sperm motility, which could be an indicator of SDF. Therefore, the decline in ICSI fertilisation rate in patients with impaired sperm progressive motility could be due to sperm DNA damage, and even ICSI cannot improve the fertilisation rate considerably. Discussion: The aim of the second part of this project was to establish a robust workflow for whole- genome amplification (WGA) and whole-genome sequencing of single cells to improve the coverage rate and fidelity, with the aim of providing means of detecting any mutation in the genome that might be responsible for reduced embryonic developmental competence. Towards this end, the efficiencies of two different WGA protocols (REPLI-g and TruePrime) were compared. Multiple technical factors required optimisation in order to create a suitable protocol. Our results demonstrated the overall superiority of REPLI-g compared to TruePrime in almost all the assessed parameters. The amplification rate of REPLI-g was much faster than that of TruePrime, and prolonged incubation led to overamplification and an increased duplication rate. However, the TruePrime method has a slower amplification rate and therefore, by increasing the incubation time, it was possible to improve the quality of the data. The modified protocol with reduced volume also had the most promising outcome in terms of the data produced, and could fulfil our expectations by being fast, cost-effective and efficient. Conclusion: In conclusion, the results from the first part of this study confirmed the negative impact of male age on assisted reproductive treatments, which can result in decreased success rates of fertilisation. Other factors such as sperm DNA damage may also contribute to this age effect, suggesting that assessing this parameter prior to fertility treatment, and attempting to mitigate elevated levels of sperm DNA damage, may be of value to older patients. Additionally, overcoming the technical challenges in studying genetic contributory factors in infertility is a promising step toward better understanding of the mutations and variations that are involved in this phenomenon.

Tato práce je zaměřena na zlepšení tepelného managementu mikroelektroniky implementací materiálů na bázi uhlíku, přesněji grafitových fólií, do tepelné architektury mikroelektroniky. Práce začíná vysvětlením současných metod chlazení a výzev v oblasti mikroelektroniky. Poté přechází k běžně používaným materiálům - hliníku a mědi a přidává do výběru i uhlíkové alotropie. Ve druhé části tato práce obsahuje několik příkladů použití pyrolytické grafitové fólie v tepelném managementu mikroelektroniky, prokazuje jeho použitelnost a analyzuje přínosy pro šíření tepla, tepelnou vodivost při dodržení elektrické izolace a možné využití ve flexibilní elektronice.

Cryocooling is a continuously developing field of engineering, applied in the fieldsof aerospace, military, and medical sciences among others. There is a demand forsmaller and more efficient cryocoolers for spaceborne low-light observation missions,with many custom cooling systems having completed successful missions. The Stir-ling cycle is the most prevalent refrigeration technique used for space applications,with the pulse-tube, Joule-Thomson or reverse Brayton cycles being used in somespecial cases.A matrix heat exchanger is designed with 3D-printed 17-4 PH stainless steel end capsstreamlined for computer numerical control (CNC) production. The heat exchanger (HX) core consists of 1mm thick stainless steel spacers and 250μm thick copperchips that are tolerance-matched for photo etching, as well as pyrolytic graphitesheets (PGS) of 25μm, the thickest commercially available PGS without addedadhesive film material.The experiments of joining PGS and copper chips with Epo-Tek 301-2 epoxy tocreate a solid core structure for the heat exchanger did not result in a pressure-resistant laminate material. The graphite surface proved difficult to adhere to usingthis epoxy, creating voids, and easily delaminated into separate layers of PGS. Bond-ing the stack together using indium, testing epoxy with a higher ability to permeatethe PGS or diffusion-bonding through other means are presented as options forfurthering the HX development.Pressure testing of a copper-only laminated heat exchanger core showed that theend cap recess adhesion capability is a potential point of failure, as the designedstructure makes it impossible to inspect the results of the bond without curingthe epoxy and pressurising the system. The difficulty in establishing a tight seambetween the main counter-flow channels of the HX is also demonstrated here, asleakage between the channels occurred at pressures in the vicinity of 2

The thermal management of electric machines is investigated with the application of techniques to a Switched Reluctance Machine and a high-speed Switched Reluctance Machine. Two novel concepts for said management of a Switched Reluctance Machine are proposed and developed: Inter-Laminate Cooling and a Continuous Toroidal Winding. The Inter-Laminate Cooling concept is developed with application to an iron core inductor which serves as a proxy for the electric machine. The experimental results confirmed the capability of the method, expressed by the effectiveness, which defines the performance measure of the applied cooling method; a concept which itself is equally applicable to other cooling methods that may be applied to any electric machine. The effectiveness also describes the gain in allowable input power to the machine which is realized to reach the same thermal limit versus the case without Inter-Laminate Cooling. The Inter-Laminate Cooling was not applied in experimental test to a Switched Reluctance Machine due to the present economic and fabrication limitations. The Continuous Toroidal Winding concept, originally conceived to permit the consideration of a fluid capillary core type of winding to enhance machine cooling, is developed to allow for peripheral cooling of the machine windings and end windings. The Continuous Toroidal Winding version of the Switched Reluctance Machine is investigated for both its thermal and electrical performance in the context of a machine that is equivalent electromagnetically to its conventional counterpart. The Continuous Toroidal Winding Switched Reluctance Machine was found to perform thermally as tested, in a manner superior to that of the conventional machine where the Toroidal machine was simulated and researched at an equivalent level of operation to the conventional machine. The electrical performance of the Toroidal Switched Reluctance Machine although supportive of the simulation analysis used to develop the machine, was not fully conclusive. This may have been due to problematic iron cores used in the construction of the experimental machines. The application of the Inter-Laminate Cooling method to a Switched Reluctance Machine is considered on an analytical basis for the special case of a High Speed Switched Reluctance Machine and found to be of net positive benefit as the machine’s iron losses are dominant over its copper losses. Application of the Inter-Laminate Cooling method to a lower speed machine, whilst beneficial, is not sufficient to significantly impact the temperature of the machine’s windings such that it would offset the loss of specific torque and power. As such, Inter-Laminate Cooling is only applicable where the net benefit is positive overall; in that the gain in input power realized is sufficient to overcome the loss of specific power and torque which will occur due to the increased machine volume. The “effectiveness” and “gain” approach for the evaluation of cooling methods applied to electric machines is a concept which should be adopted to aid in the comparative understanding of the performance of myriad different cooling methods being applied to electric machines both in research and practice, of which there is only minimal understanding. / Thesis / Doctor of Philosophy (PhD)

Pain is a very common problem experienced by the general population and children in particular. It goes beyond personal suffering and affects all dimensions of the quality of life and general functioning of both adults and children, be it the physiological, psychological or financial aspects. Children may suffer from pain that may either be chronic or acute, depending on the diagnosis. Assessment of pain in children is equally important as that of adults, except that they lack the verbal fluency and cognitive development to communicate their pain. Children’s experience of pain is similar to that of adults. Pain assessment is a key aspect in the nursing management of children and delivery of care within the Primary Health Care (PHC) setting. Effective pain assessment is thus reliant on comprehensive assessment of the child and his or her pain. The aim of this research was to explore and describe practices and perceptions of professional nurses working in a PHC facility regarding pain assessment of children under five years in the Mangaung Metropolitan Municipality and to formulate recommendations for professional nurses in PHC facilities to facilitate pain assessment in PHC settings. A qualitative study design was used and data was collected with the use of focus groups. A purposive sampling was conducted to select participants who represent the target population. The sample used for the study included all the professional nurses working in PHC facilities registered with the South African Nursing Council and that have at least one year of experience. The practical training of the researcher to conduct an interview was done prior to the actual research. A pilot focus group was conducted and the interview schedule was finalised. Semi-structured focus groups were used to obtain data from the participants. The researcher conducted 6 focus group interviews attended by 32 professional nurses. Data was collected until data saturation was achieved. Trustworthiness was ensured in accordance with the principles of credibility, transferability, dependability and confirmability. Data was captured on a digital voice recorder and transcribed verbatim. Field notes were taken during each focus group. Data analysis was done by means of content analysis by the researcher and an independent co-coder. After consensus and saturation, three major themes emerged. Each theme was identified and divided into sub-themes and was consequently discussed together with the relevant data obtained from literature. The findings indicated that professional nurses perceive the assessment of pain in children under five years as a challenge. The combination of signs and symptoms to make decisions with pain assessment was identified as an area of concern. The participants further p erceived the history provided by the parent as important in the process of pain assessment. The conclusions drawn are that the professional nurses acknowledge that they don’t take sufficient notice of pain in children under five, which means that children with pain are neglected. Professional nurses maintain that there is a need for sufficient pain assessment and the need for guidelines and tools to assess pain in children under five, especially in the PHC setting. These professional nurses support the availability of guidelines to assist them to conduct effective and comprehensive pain assessment. The research report concluded with the researcher’s recommendations for nursing education, nursing research and nursing practice with specific formulation of guidelines for the facilitation of professional nurses to truly render effective and comprehensive pain assessment in PHC settings. / Thesis (MCur)--North-West University, Potchefstroom Campus, 2013.

Pain is a very common problem experienced by the general population and children in particular. It goes beyond personal suffering and affects all dimensions of the quality of life and general functioning of both adults and children, be it the physiological, psychological or financial aspects. Children may suffer from pain that may either be chronic or acute, depending on the diagnosis. Assessment of pain in children is equally important as that of adults, except that they lack the verbal fluency and cognitive development to communicate their pain. Children’s experience of pain is similar to that of adults. Pain assessment is a key aspect in the nursing management of children and delivery of care within the Primary Health Care (PHC) setting. Effective pain assessment is thus reliant on comprehensive assessment of the child and his or her pain. The aim of this research was to explore and describe practices and perceptions of professional nurses working in a PHC facility regarding pain assessment of children under five years in the Mangaung Metropolitan Municipality and to formulate recommendations for professional nurses in PHC facilities to facilitate pain assessment in PHC settings. A qualitative study design was used and data was collected with the use of focus groups. A purposive sampling was conducted to select participants who represent the target population. The sample used for the study included all the professional nurses working in PHC facilities registered with the South African Nursing Council and that have at least one year of experience. The practical training of the researcher to conduct an interview was done prior to the actual research. A pilot focus group was conducted and the interview schedule was finalised. Semi-structured focus groups were used to obtain data from the participants. The researcher conducted 6 focus group interviews attended by 32 professional nurses. Data was collected until data saturation was achieved. Trustworthiness was ensured in accordance with the principles of credibility, transferability, dependability and confirmability. Data was captured on a digital voice recorder and transcribed verbatim. Field notes were taken during each focus group. Data analysis was done by means of content analysis by the researcher and an independent co-coder. After consensus and saturation, three major themes emerged. Each theme was identified and divided into sub-themes and was consequently discussed together with the relevant data obtained from literature. The findings indicated that professional nurses perceive the assessment of pain in children under five years as a challenge. The combination of signs and symptoms to make decisions with pain assessment was identified as an area of concern. The participants further p erceived the history provided by the parent as important in the process of pain assessment. The conclusions drawn are that the professional nurses acknowledge that they don’t take sufficient notice of pain in children under five, which means that children with pain are neglected. Professional nurses maintain that there is a need for sufficient pain assessment and the need for guidelines and tools to assess pain in children under five, especially in the PHC setting. These professional nurses support the availability of guidelines to assist them to conduct effective and comprehensive pain assessment. The research report concluded with the researcher’s recommendations for nursing education, nursing research and nursing practice with specific formulation of guidelines for the facilitation of professional nurses to truly render effective and comprehensive pain assessment in PHC settings. / Thesis (MCur)--North-West University, Potchefstroom Campus, 2013.

Compliance mismatch is a significant hurdle to long-term patency in small-diameter arterial bypass grafts. Vascular tissue engineering has the potential to produce compliant, non-thrombogenic small-diameter grafts. However, current engineered grafts are relatively non-compliant, resulting in intimal hyperplasia and graft occlusion when subjected to arterial pressures. This research investigates the mechanical and biological properties of engineered constructs based on a biodegradable synthetic elastomer, poly(glycerol sebacate) (PGS). Several methods for fabricating porous PGS scaffolds in a tubular geometry were developed and compared. Adult baboon vascular cells were cultured in the scaffolds under various in vitro experimental conditions, including variations in initial cell seeding density, the type of scaffold used for culture, culture time, scaffold material, and hydrostatic pressure, and properties of the resultant constructs were compared. Scaffold fabrication using heat-shrinkable mandrels and glass tubes coated with hyaluronic acid significantly decreased tolerances of wall thickness and mechanical properties, improved handling, and decreased culture time required to reach luminal cellular confluence compared to scaffolds made with other fabrication techniques. Altering scaffold material from PGS to poly(lactide-co-glycolide) (PLGA), a benchmark biomaterial, did not affect scaffold yield, porosity, or luminal cellular confluence. Extracellular matrix (ECM) deposition increased with SMC-only culture time, and ECM deposition and remodeling during culture influenced construct compliance. Compared to PLGA scaffolds, PGS scaffolds promoted elastin crosslinking by SMCs and elastic tissue properties but attenuated collagen deposition. Hydrostatic pressure promoted ECM synthesis and deposition by SMCs and decreased construct compliance. Collagen and crosslinked elastin content in constructs correlated positively with construct burst pressure, and a negative correlation dependent on scaffold type was found between collagen content and construct compliance at low pressures. The systematic investigation of culture conditions in this research provides insights into the control of engineered blood vessel properties. The central hypothesis of this work, that grafts engineered from PGS scaffolds and adult vascular cells under biomimetic in vitro culture conditions can possess compliance comparable to autologous vessels, is true at pressures below 60 mmHg and demonstrates potential for PGS-based vascular tissue engineering. Overall, this work provides tools for engineering tubular soft tissues based on porous PGS scaffolds.

Factors currently at the forefront of human in vitro fertilization (IVF) that collectively influence treatment success in the form of blastocysts development were investigated during early mammalian embryology with concentration on infertile patients presenting with diminished ovarian reserve or preliminary ovarian failure. A novel experimental technique, Graft Transplant-Embryonic Stem Cells (GT-ESC) was introduced in the mouse model, as the first inclusive approach for embryo selection in IVF treatments resulting in successful graft integration of sibling cells, stage-dependent (day 4) blastocysts. E-Cadherin-catenin bonds play an integral role in trophectoderm cell viability and calcium removal, inducing disruption of cell-to-cell bonds at the blastocyst stage was detrimental to continued blastocyst development. One of the leading methods for embryo selection for uterine transfer in human IVF is application of pre-implantation genetic screening (PGS) methods such as next generation sequencing (NGS). Female patients <35 y do not benefit from this treatment when outcome is measured by presence of fetal heart beats at 10 weeks of gestation. Patients 35-37 y benefit from PGS with no significant difference of outcome based on form of PGS method utilized. Therefore, small nucleotide polymorphism array (snp-array) or targeted-NGS should be selected for this age range to lessen the financial burden of the patient. Embryos from women >40 y have a higher rate of mosaic cell lines which can be detected by NGS. Therefore NGS is most beneficial for women >40 y. Additionally, ovarian stimulation of the patient during human IVF can notably influence outcome. Anti-Müllerian hormone (AMH) is a more conducive indicator of blastocysts development per treatment compared to basal follicle stimulating hormone (FSH). Actionable variables included in a decision tree analysis determined a negative influence (0% success, n=11) of high dose gonadotropin use (>3325 IUs) in good prognosis patients (>12 mature follicles at trigger, AMH >3.15 ng/mL). A positive relationship exists (80% success, n=11) between poor responders (AMH <1.78 ng/mL, <12 mature follicles at trigger) and high dose gonadotropin use (>3025 IUs). Utilizing the decision tree during IVF treatment can be beneficial to treatment success. Moreover, a parallel relationship of the fundamental principles of culture medium pH, pCO2 and pO2 was found with respect to blastocyst development. Human infertility patients' gametes predisposed to primary stressors (i.e., age, genetics and etiology) are negatively impacted (~30% success, n=7) for cleavage stage (day 3) embryo development when primary culture medium has pCO2 <30mmHg given age >31 y and <14 oocytes retrieved. When day 3 embryo development is measured at >65% good quality embryos per treatment (based on SART grading criteria), blastocysts development success is highest when secondary culture medium pO2 is 69-88 mmHg (~90% success, n=12). Thus, IVF treatment outcome can be optimized with utilization of predictive model analyses in the form of decision trees providing greater success for the IVF laboratories, ultimately decreasing the emotional and financial burden to infertility patients.