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A dissertation submitted in fulfilment of the requirements for the Degree of Master of Science in Archaeology to the Faculty of Science, University of Witwatersrand, 2019 / The study examines the technology of crystal quartz pieces from Pomongwe Cave (PMG), Matopos, and south-western Zimbabwe. It focuses on the Middle and Later Stone Age (MSA and LSA) assemblages, which were excavated in the early 1960s by C. K Cooke and is housed at the Zimbabwe Museum of Human Sciences (ZMHS) in Harare. The research employs the chaîne opératoire approach to the study of crystal quartz technology, which follows all the stages of lithic production from the sourcing of the raw material through exploitation, use and discard patterns. It seeks to understand how the hunter-gatherers at Pomongwe (PMG hereafter) exploited this material and how they adapted their technologies to suit the physical and mechanical properties of crystal quartz through time at the site. On a broader scale, the study contributes to our understanding of the development of Modern Human Behaviours (MHBs). The results of the study show that the sourcing of the crystals was mainly from a secondary context throughout the MSA and LSA sequence. The presence and distribution of the material also varied throughout the MSA and LSA sequence, suggesting that the raw material was more prominent with the inhabitants during certain periods than others. The results through classification also show that not all collected crystals were exploited for lithic production, which raises questions as to why they were collected. The cores and blanks show that the crystals were mainly opened from the pyramid and exploited going towards the base of the crystal. The most notable change in the exploitation of crystal quartz throughout the MSA and LSA sequence at PMG is that of the reduction in the sizes of the blanks going towards the LSA. / TL (2020)

Indiana University-Purdue University Indianapolis (IUPUI) / The use and abuse of fentanyl has risen drastically over the last several decades. The abuse of this substance has created a hazardous situation for law enforcement and first responders because they could arrive at locations and not necessarily know that they will encounter fentanyl or a fentanyl analog. Fentanyl analogs are substances that have a similar structure to fentanyl, and while the analogs may have additional or altered groups on the molecule, the backbone structure remains similar. This work focus on the electrochemical characterization of fentanyl as a stepping stone for the detection of both fentanyl and later fentanyl analogs by electrochemistry. The metabolic reaction of fentanyl is an N-dealkylation to norfentanyl, occurring in the liver, and can be mimicked by electrochemistry through the irreversible oxidation of fentanyl. This electrochemical reaction is hypothesized to generate electroactive metabolites in solution. The combination of the visualization of both the irreversible oxidation with the development of the additional metabolic electrochemical peaks would constitute a unique electrochemical signature for fentanyl and fentanyl analogs towards a universal rapid screening assay. The electrochemical behavior of fentanyl was characterized in depth using multiple electrochemical techniques such as cyclic voltammetry (CV), square wave voltammetry (SWV) and differential pulse voltammetry (DPV). The optimization of the supporting electrolyte, the potential range, and methods to decrease the background current were explored with CV. To work towards a more portable system, screen printed electrodes were used. The observation of the metabolic peaks remained challenging, and different methods were attempted to achieve it. The quantification of fentanyl was successfully demonstrated using the different electrochemical systems proposed in this work. The electrochemical characterization of fentanyl and the optimization of multiple experimental parameters were the first step in developing a universal, rapid, electrochemical sensing method for the detection of fentanyl and fentanyl analogs. / 2023-02-28

Nowadays, water pollution significant jeopardizes the continuous clean drinking water supply that results in the damage of human health, and economy development. Adequate sensors are not only able to greatly benefit the treatment process but also can continuous monitoring of the watershed for contaminates which help effectively control pollution and manage the water resources. However, the commercial available sensors are expensive and required frequently maintenance. These limitations make these sensors not sufficient in continuous water monitoring application. In this thesis, sensors for some of the essential sensing targets including dissolved oxygen, phosphate and chlorine are developed. These sensors are low cost, easy operation and minimum maintenance required. These advantages make the sensors suitable to be applied in the continuously water quality monitoring system in multiple water systems such as drinking water, surface water and wastewater. Furthermore, an all solid state rechargeable palladium nanostructure based reference electrode and a universal dopamine/PEG/albumin antifouling coating technique are also studied in order to further extend the lifetime of these sensor thus reduces the need of maintenance. / Thesis / Doctor of Philosophy (PhD)

PEC bioanalysis represents a unique and dynamically developing methodology that offers an elegant route for sensitive biomolecular detection. Building on the principle of EC analysis, PEC biosensors harness the unique properties of optically active species to enhance analytical performance. Owing to the current based outputs evolved in both PEC and EC bioanalysis, they can be miniaturized and potentially integrated with handheld and portable analyzers, making them uniquely positioned as tools to build effective POC diagnostics. The commercialization of PEC technology for building POC diagnostics, however, heavily depends on enhancing the stability of the photoelectrodes upon repeated use, lowering the limit-of-detection (LOD) of the PEC biosensor used, enhancing the efficiency of signal transduction and the ability of the device to detect minute amounts of biomolecular target in complex biological matrices. In order to address these constraints, we first developed a new solution-based strategy integrating inorganic semiconductive species (titanium dioxide) in an organic framework to construct photoelectrodes with enhanced signal baselines and adequate stability for the cyclic measurements required in biosensing. These transducers were subsequently used to investigate the interaction mechanisms (wavelength dependency, coverage density dependency and spatial dependency) between plasmonic NPs (Au) and the photoelectrodes —chosen as model materials—with the goal of enabling predictive dual-signal modulation and enhanced limit-of-detection in PEC biosensors. The understanding gained was used to design a dual-signal PEC transduction strategy—operated at a single excitation wavelength and on a single electrode—to detect nucleic acid sequences in urine without direct target labeling, target amplification or target enrichment. Here, Au NP terminated biobarcodes served as dynamic signal amplifiers that enabled a low limit-of-detection (5 fM), a wide linear range (1 fM – 100 pM), and the ability to discern between single and double base-mismatched nucleic acid sequences. In parallel, we also detail the development of an EC biosensor featuring dynamic DNA motifs, capable of reagentless, sensitive and specific detection of N-PEDv (nucleocapsid protein of porcine epidemic diarrhea virus)—a protein target with emerging global significance—in both buffer (LOD ~ 1.08 μg mL-1) and urine (LOD ~ 1.09 μg mL-1) Ultimately, this work presents innovations in material architecture and programmable dual-signal transduction that enhance the performance metrics of biosensors; thus, presenting the potential to design POC molecular diagnostics of the future. / Thesis / Doctor of Engineering (DEng) / To address critical limitations in the field of point-of-care molecular diagnostics, it is vital to develop new tools integrating bio-recognition systems with programmable photoelectrochemical and electrochemical signal transduction that enables the design of more effective biosensors. In photoelectrochemical (PEC) systems, plasmonic materials such as gold nanoparticles are often featured to either amplify or attenuate signal response. While there is a significant amount of literature regarding the interaction of gold nanoparticles (Au NPs) with semiconductive systems, the exact nature of the interaction between the two particles has not yet been fully mapped out. In this thesis, we examine various degrees of freedom—including surface coverage density and separation distance—that influence the design of effective photoelectrochemical systems. The understanding gained is further harnessed to design dual-signal photoelectrochemical systems featuring titanium dioxide (TiO2) photoelectrodes and Au linked dynamic deoxyribonucleic acid (DNA) motifs to enable predictive modulation in response to target identification. An electrochemical (EC) analogue featuring structure switching DNA motifs and redox tagged barcodes was also developed. The resultant PEC and EC biosensing assays were critically examined, and their analytical performance was subsequently evaluated in terms of limit-of-detection, sensitivity, and specificity. Ultimately, new classes of bioassays featuring integrated biorecognition and dual-signalling capability for oligonucleotide (i.e., nucleotide sequences and aptamers) based biomolecular detection in urine and saliva were realized.

Climate change, industrial and agricultural activities, and population growth exacerbate global water stress. A variety of advanced technologies have been studied to alleviate water scarcity and water pollution. Membrane technology owing to its low footprints and ease of operation, has drawn intensive attention for water purification and wastewater treatment. Further, integrating membrane technology, electrochemistry and catalysis can improve separation and selectivity of the filtration process. This work aims to fabricate high-performance active and reactive ultrafiltration membranes involving electrically conductive membranes, catalytic membranes and electrocatalytic membranes. Their use in water treatment inspires the development of advanced functionalized membranes and further accelerates the transition to industrial applications. / Thesis / Doctor of Engineering (DEng)

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