Magister Scientiae (Medical Bioscience) - MSc(MBS) / Aim: Leukocytes are the major source of reactive oxygen species (ROS) in the ejaculate and contribute to up to 30% of male infertility. ROS have been associated with markers of apoptosis such as sperm DNA damage, externalization of phosphatidylserine and caspase-3 activation. Therefore, this study aimed at investigating the impact male genital tract infections/inflammations on the induction of apoptosis in spermatozoa.Materials and Methods: Semen samples were obtained from 60 men consulting for fertility problems at the Reproductive Biology Unit, University of Stellenbosch at Tygerberg Academic Hospital, and Vincent Pallotti Hospital (Cape Town, South Africa). To investigate the relationship between male genital tract infection and sperm apoptosis, the following were measured: semen parameters including sperm count, motility and forward progression; oxidative status in the ejaculate by evaluating the concentration of seminal leukocytes, ROS production in the ejaculate,generation of O2-• and H2O2 by spermatozoa, and the activity of reduced glutathione(GSH) in sperm; sperm apoptotic markers by measuring mitochondrial membrane potential (Δψm), caspase-3/7 activation, and DNA fragmentation (TUNEL).Results: The concentration of seminal leukocytes had a significant positive correlation with ROS production in the ejaculate (ρ=0.378; P=0.0064), sperm O2-• production (ρ=0.336; P=0.0098), and caspase-3/7 activation in sperm (ρ=0.527;P<0.0001). Furthermore, at the cutoff value of ≥0.25×106 leukocytes/mL of semen,the concentration of peroxidase-positive cells correlated significantly with sperm GSH activity (ρ=0.718; P=0.008), the percentage of sperm with disrupted Δψm(ρ=0.465; P=0.043), caspase-3/7 activation in sperm (ρ=0.794; P=0.001), and the percentage of sperm with fragmented DNA (ρ=0.563; P=0.017). ROS production in the ejaculate, besides the association with seminal leukocytes, was also correlated with the sperm count (ρ= -0.296; P=0.033), sperm GSH activity (ρ=0.577; P<0.0001),caspase-3/7 activation in sperm (ρ=0.487; P=0.0005), and sperm DNA fragmentation(ρ=0.331 P=0.0171). Caspase-3/7 activation was strongly correlated with oxidative stress in both, the ejaculate and in spermatozoa; although this parameter was not correlated with sperm Δψm and DNA fragmentation. Sperm O2-•, which had a link with seminal leukocyte concentration, was significantly correlated to sperm Δψm(P=0.0098), as was sperm GSH activity (P=0.0055). Sperm DNA fragmentation was positively correlated with ROS in the ejaculate and sperm H2O2-production(P=0.039). Conclusions: Excessive ROS in the ejaculate, mainly a consequence of seminal leukocytes, is not only linked to internal generation of O2-•, but also to sperm DNA fragmentation and the activation of effector caspases. Moreover, even in nonleukocytospermic patients with ≥0.25×106 leukocytes/mL of semen, oxidative stresscan occur which can trigger apoptosis, caspase-3/7 activation, and induce sperm DNA fragmentation. Therefore, it is possible that male genital tract infection, the major cause of leukocyte infiltration in the male reproductive tract, can induce apoptosis, of which the observed sperm DNA fragmentation is a late feature.

Thesis (M.S.)--Rochester Institute of Technology, 2006. / Typescript. Includes bibliographical references (leaves 132-137).

Thesis (Ph. D.)--University of Iowa, 2007. / Supervisor: Shaoping Xiao.. Includes bibliographical references (leaves 174-182).

published_or_final_version / abstract / toc / Mechanical Engineering / Master / Master of Philosophy

Thesis (M.A.)--Indiana University, 2008. / Title from screen (viewed on August 27, 2009). Department of English, Indiana University-Purdue University Indianapolis (IUPUI). Advisor(s): Ulla Connor, Aye Nu E. Duerksen, Honnor Orlando. Includes vita. Includes bibliographical references (leaves 68-70).

Thesis (Ph. D.)--University of Texas at Austin, 2007. / Vita. Includes bibliographical references.

Room temperature photomodulated reflectance (PR), Photoluminescence (PL) and double crystal x-ray diffraction (DCXRD) measurements have been performed on a series of tensilely strained InxGa1-xAs (0.316 &le; x &le; 0.533) multiple quantum well (QW) structures, with In0.80Ga0.20As0.43P0.57 barriers. The DCXRD measurements provided accurate information on composition, strain and layer thickness, while PR was used to determine the energies of the full manifold of allowed and forbidden critical point interband QW transitions. A three-band effective mass formalism was used to model the QW transitions to derive structural information on each sample. The energies of the ground-state QW transitions, H11 and L11, were found to increase with tensile strain, becoming degenerate near 0.36% tensile strain. Room temperature PR and conventional reflectance (R) measurement have been performed on two I.R. emitting InGaAs/GaAs/A1As vertical cavity surface emitting laser (VCSEL) structures. The R measurements were modelled using a transfer matrix formalism to determine errors in the growth fluxes. A new PR lineshape model has been developed based on energy dependent Seraphin coefficients, to describe the cavity mode interaction with a confined-state QW transition. The model is demonstrated on a set of PR spectra, and used in a novel way to derive the Deltaepsilon2 spectrum of the QW layers directly. The results are compared with those taken of the QW layers directly after removing the top Bragg stack reflector. Whilst the QW layers in one sample were found to be close to nominal, the in composition of QW in the other sample was found to depart significantly from the nominal 23%, and was found to be 28%. Room temperature and ~ 80K PR measurements were performed on three InAs/GaAs self-assembled quantum dot (QD) structures: a sample with a single layer of QDs, and two with two layers. The PR revealed five equally spaced confined-state QD transitions, at both 80K and room temperature, with ~ 54 meV separation. The behaviour of the QD1 transition as a function of temperature was investigated and an anomalous increase in linewidth was observed on cooling. Annealing of one of the samples produced a strong blue shift (~ 250 meV) and narrowing of the QD transitions.

No / With increasing interest in hot melt extrusion for preparing polymer-drug systems, knowledge of the shear and extensional rheology of polymers is required for the formulation and process design. Shear and extensional rheology of three commercial grades of hydroxypropyl cellulose (HPC) was examined at 140, 145 and 150 degrees C using twin bore capillary rheometry at range of processing rates. The power law model fitted for shear flow behaviour up to shear strain rates of approximately 1000s(-1), above which measured shear viscosities deviated from the power law and surface instabilities were observed in the extrudate, particularly for higher molecular weight grades. Shear thinning index was found to be relatively independent of temperature and molecular weight, whilst the consistency index, indicative of zero shear viscosity increased exponentially with increase in molecular weight. Extensional viscosity of all grades studied was found to decrease with increasing temperature and increasing processing rate. Foaming of the extrudate occurred especially at low temperatures and with the high molecular weight grade. An understanding of the relationships between shear and extensional flows with temperature, processing rate and molecular weight is a useful tool for process design; optimisation and troubleshooting of Hot melt extrusion (HME) of pharmaceutical formulations.

Thesis (M. Ed. (Curriculum Studies)) -- University of Limpopo, 2021 / The purpose of the research was to explore challenges encountered by teachers when teaching fractions to learners in grade 2 at schools in the Koloti Circuit. A qualitative approach including other research techniques, such as observation, document analysis and interviews, were mutually employed to collect data during the study. A pluralistic approach was employed when gathering data to enhance triangulation and further intensify the merits of the probed facts. Purposive sampling was employed to choose three grade 2 teachers from various schools to serve as participants in this study. The following challenges were uncovered as a result of the research: learners are from child-headed families; there is a high rate of learner absenteeism; parents do not attend consultative meetings; there is a high rate of teacher time-offs; there is a lack of teacher pedagogical content knowledge in mathematics; teachers have to teach in multi-grade classroom; teachers lacking background knowledge on implementation of inclusive classrooms resulting in inadequate support to learners with learning barriers; classrooms are over-crowded; uneven partitioning of circular representations was discovered, and there is lack of content-related workshops. The following were some of the recommendations that were established to counteract the challenges uncovered during the research study, namely: establishment of after-care centres with qualified tutors; provision of state paid security services in schools; teachers should create learner support materials to aid in the teaching of fractions to the learners; teachers should notify parents when their children are absenting themselves from school on regular basis without valid reasons; teachers should notify parents about the benefits of attending consultative meetings; memorial services for teachers should be conducted after learner contact time, competent and/or qualified teachers in arithmetic should be assigned to educate the subject; small schools should be merged to curb multi-grate teaching at schools; more classrooms should be provided to avoid over-crowding in the classrooms, and more content workshops should be organised in order to assist teachers who experience challenges with the teaching of fractions. In conclusion, the outcomes of this study could aid grade 2 teachers in instilling knowledge of fractions into their learners, crafted on the suggested recommendations that are drawn subsequent the challenges facing teachers were singled out, in order to improve learner performance in fractions. This could result in better performance by learners in mathematics at various schools.

To provide a basis for the development of interaction curves for tubular beam-columns of annular cross section, a general purpose beam-column computer program is developed, and used to determine ultimate load capacities. The paper presents the analytical model and the computer method. The analytical results are compared with published test data as well as experimental data obtained as part of this project.