A dissertation submitted to the Faculty of Science, University of the Witwatersrand in partial fulfilment of the requirement for the degree Master of Science (M.Sc.) in Chemistry. Johannesburg, 31 October 2017. / Nanotechnology has been instrumental in finding strategies of combating some of the world’s grand challenges. Water scarcity and the growing industrialization have made it an imperative to find ways of cleaning water. Photocatalysis is a promising method for water purification personified by the use of solar energy as well as nanomaterials with tailored properties. Colloidal synthesis has made it possible to synthesize new materials with tailored properties, in particular the single-source precursor method has been found to be a useful method in synthesizing nanomaterials with high purity. In the synthesis of metal chalcogenides, the single-source precursor method has an advantage of the precursor having the desired metal-chalcogenide bond hence eliminating the possible formation of side products particularly metal oxides. Herein, acylthiourea (ATU) and thiourea (TU) zinc complexes were used as precursors for the synthesis of ZnS nanoparticles. Bis(N,N-diethyl-N’-benzoylthiourea)Zn(II) [Zn(ATU)2] and bis(diaminomethylthio)Zn(II) chloride [Zn(TU)2Cl2] complexes were synthesized using a conventional method and characterized with elemental analysis, 1H NMR , 2D NMR, COSY, FTIR, mass spectrometry and X-Ray crystallography. The resultant precursors, Zn(ATU)2 and Zn(TU)2Cl2 complexes were then thermolyzed to yield ZnS nanocrystals and characterized fully. Reaction parameters that included the synthetic time, temperature, concentration and capping agents were optimized for each single-source precursor in an attempt to control the nanoparticles yielded hence their properties. Time and temperature studies generally demonstrated the most pronounced effect and with an increase, they showed increasing particle sizes through the Ostwald ripening effect. Also visible from the TEM was that the temperature had an effect on the morphology of the nanoparticles. Increasing the precursor concentration resulted in the agglomeration of nanoparticles, while using different capping agents yielded similar nanoparticles with different degrees of agglomeration. Evident from the results the ATU precursor behaved similar to the TU precursor and generally the particles obtained from the two precursors regardless of the reaction condition were very small. Preliminary investigations into the use of the synthesized nanoparticles obtained from the two precursors revealed potential in photocatalytic degradation of Rhodamine B (RhB) dye in water. While smaller particles were obtained from the synthesized nanoparticles, the degradation efficiencies were lower than the commercial ZnO and TiO2. This is due to the presence of the long-chained capping agents on the synthesized particles blocking the interaction of the core ZnS and the light. / LG2018

A PhD thesis submitted to the Faculty of Engineering and the Built Environment, University of the Witwatersrand, Johannesburg, in fulfilment of the requirements for the degree of Doctor of Philosophy in Engineering. Johannesburg / This study involves the investigation of the paint wastewater treatment using inorganic coagulants such as FeCl3, Fe2(SO4)3, AlCl3 and Al2(SO4)3 in a jar test during rapid and slow mixing for 250 and 100 rpm respectively, settled the samples, measure the pH and turbidity. The pH, turbidity and area covered by the flocs were used as measurements in this study to determine the quality of treated paint wastewater. In the first experiment, 200 mL sample of 169.2 g of paint wastewater dissolved in 1L of potable water was poured into six 500 mL glass beakers sample dosed with FeCl3 only, combined FeCl3 and Ca(OH)2 or Mg(OH)2 as well as FeCl3-Ca(OH)2 and FeCl3-Mg(OH)2 polymers respectively, run through a jar test with rapid and slow mixing. The supernatant was extracted after 1 hour settling to measure the pH and turbidity. The observations showed that combined FeCl3 and Mg(OH)2 as well as FeCl3-Mg(OH)2 polymers yielded identical and slightly higher turbidity removal than combined FeCl3 and Ca(OH)2 and FeCl3-Ca(OH)2 polymers. Another batch of experiments was carried out using the same metal salts with Ca(OH)2 and Mg(OH)2 respectively for pH adjustment. The samples were treated in a jar test using various dosing patterns such as dosages, dosing prior or during mixing, combined dosages interchangeably, retention time. A third batch of experiments was carried out by dosing synthetic polymers of FeCl2-Ca(OH)2 and FeCl2-Mg(OH)2 respectively using similar dosing patterns. The results obtained in first set of experiments, were Fe3+ and Al3+ salts were added in paint wastewater showed that the changing pH correlates with turbidity removal. It was also observed that dosing prior or during mixing do not play any significant role in wastewater treatment. Another observation showed that flocculation of the paint wastewater dosed with FeCl2-Ca(OH)2 or FeCl2-Mg(OH)2 polymers do not show correlation between the pH and turbidity, which indicates that the pH is not an indicator of turbidity removal in a more alkaline solutions such as paint wastewater. A second study was carried out using the same paint wastewater samples (200 mL) and samples dosed with Fe3+ and Al3+ salts treated in a jar test and immediately two drops of supernatant were placed on a microscope slide and view it under a microscope connected to a camera, images were captured after 1, 60 and 90 minutes respectively (Exp A). Samples were prepared from the original paint wastewater and the standard solution of Fe3+ and Al3+ in a small scale using identical metal salt/paint wastewater volume ratios as above. Two drops from the paint wastewater and metal salt solution were place on a microscope slide and images were captured as above using 1, 60 and 90 minutes respectively (Exp B). All the visuals were printed and the visuals obtained in Exp A were compared with their corresponding visuals in Exp B in accordance with time. The results obtained showed that the percentage area covered by flocs treated in a jar test (Exp A) correlates linearly with the percentage area covered by the flocs from a microscope slide (Exp B). The results obtained using this technique also confirm that the reaction between the drops of a sample and the drops of coagulant produces well-developed solid hydrolysis species. A third study was carried out by pouring 200 mL of the same paint wastewater samples into six 500 mL glass beakers and with Fe3+ and Al3+ salts as above, run through a jar test during 30, 45 and 60 seconds rapid mixing (250 rpm) only for 2 minutes respectively. The samples settled for 1 hour, and then pH and turbidity were measured. Another experiment was carried out using the similar method as above with samples run through a jar test at 250 rpm during 30, 45 and 60 seconds rapid mixing (250 rpm) for 2 minutes followed by slow mixing (100 rpm) for 10 minutes (combined rapid and slow mixing). The samples settled for 1 hour, and then pH and turbidity were measured. The results obtained from the jar tests (comparison between flocculation during rapid mixing only and combined rapid and slow mixing) showed that the pH in the samples with rapid mixing shows an insignificant change compared to their corresponding samples with combined rapid and slow mixing; turbidity in the samples with 30, 45 and 60 seconds rapid mixing showed that most of the flocs are formed within 30 seconds. There is a correlation between the pH and turbidity when paint wastewater is dosed with Fe3+ or Al3+ metal ions in their respective metal salts without pH adjustment. The Fe3+ and Al3+ of the same concentration yield a similar pH and turbidity trend.

這篇論文研究了幾種基於聚二甲基硅氧烷（PDMS）的微流控芯片，及其對於酶反應和蛋白質結晶的應用。 / 本論文分為兩部份。首先，論文第一部份介紹了兩種微流控芯片。利用到PDMS透氣的性質，第一種微流控芯片是一種基於脫氣PDMS的納升液體進液系統。在第一種微流控芯片的基礎上，我們引進一種可由普通注射器控制的氣閥控制系統，可對反應液體的分配和混合進行更方便和精確的操作。兩種芯片均成功應用於酶反應動力學的測定。在一次實驗中，只需要3~5微升的反應物就可以得到鹼性磷酸酶（alkaline phosphatase）的Michaelis-Menten動力學。 / 論文第二部份研究了“體積效“應對於蛋白質結晶的影響。首先，基於微孔的微流控芯片的蛋白質結晶篩選實驗揭示了在小體積（納升）下，蛋白質的結晶條件比在大體積（微升）下更多。在液滴里的蛋白質結晶實驗結果說明大體積的蛋白質液滴結晶速度更快。最後，蛋白質結晶實驗成功在雙乳液（double emulsion）的內核中進行。 / This thesis describes the design and development of micro dispensing systems for enzyme assay and for protein crystallization. The micro dispensing systems were fabricated by the soft-lithography method with the widely used material poly(dimethylsiloxane) (PDMS), which is gas and water permeable elastomer. / This thesis contains two major parts. In the first part, enzyme assay was performed in two micro dispensing systems, one based on microwells and the other based on pneumatic valves. The complete Michaelis-Menten kinetics measurement of the alkaline phosphatase (AP) with different fluorescein diphosphate (FDP) was achieved in one chip for each system using the fluorescence detection. These micro dispensing systems’ fabrication and operation were simple, and the total sample consumption was about 3~5 μL. / The second part reports the study of the volume effect on protein crystallization. Three micro dispensing systems, the microwell-based, droplet-based and double emulsion-based systems, were developed to perform the protein crystallization. Lysozyme and thaumatin were chosen as the model proteins. First, the protein crystallization screening experiments showed that protein crystallized in more precipitant conditions in the microchip than in conventional microbatch system. Second, the protein crystallization results carried out in droplets showed that protein crystallized faster in larger droplets. Finally, the protein crystallization in double emulsions was demonstrated. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Detailed summary in vernacular field only. / Zhou, Xiaohu. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2012. / Includes bibliographical references (leaves 87-91). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese. / Abstract --- p.i / 摘要 --- p.iii / Acknowledgements --- p.iv / Table of Contents --- p.vi / List of figures --- p.viii / Chapter Chapter 1 --- Introduction to microfluidics --- p.1 / Chapter 1.1 --- Fabrication of microfluidic devices --- p.2 / Chapter 1.1.1 --- PDMS-based microfluidic device --- p.2 / Chapter 1.1.2 --- PMMA microfluidic device --- p.6 / Chapter 1.1.3 --- Assembly of the microfluidic device --- p.8 / Chapter 1.2 --- Degassed PDMS pumping method --- p.9 / Chapter 1.3 --- Droplet-based microfluidics --- p.13 / Chapter 1.4 --- Thesis organization --- p.16 / Chapter Chapter 2 --- Micro dispensing systems for enzyme assay --- p.17 / Chapter 2.1 --- Introduction to enzyme assay --- p.17 / Chapter 2.1.1 --- Introduction to micro platforms for enzyme assay --- p.17 / Chapter 2.1.2 --- Introduction to enzyme kinetics and Michaelis-Menten kinetics --- p.21 / Chapter 2.2 --- Experimental --- p.26 / Chapter 2.2.1 --- Design of the micro dispensing systems --- p.26 / Chapter 2.2.2 --- Fabrication of the microfluidic devices --- p.30 / Chapter 2.2.3 --- Reagents and operation --- p.32 / Chapter 2.3 --- Results and discussion --- p.32 / Chapter 2.3.1 --- Microwell-based dispensing system --- p.32 / Chapter 2.3.2 --- Micro dispensing system based on pneumatic valves --- p.40 / Chapter 2.4 --- Conclusions --- p.45 / Chapter Chapter 3 --- Micro dispensing systems for protein crystallization --- p.47 / Chapter 3.1 --- Introduction to protein crystallization --- p.47 / Chapter 3.1.1 --- Principle of protein crystallization --- p.49 / Chapter 3.1.2 --- From macrofluidics to microfluidics --- p.51 / Chapter 3.2 --- Experimental --- p.56 / Chapter 3.2.1 --- Design of the micro dispensing systems --- p.56 / Chapter 3.2.2 --- Fabrication of the microfluidic devices --- p.58 / Chapter 3.2.3 --- Reagents and operation --- p.60 / Chapter 3.2.4 --- Layer-by-layer modification --- p.61 / Chapter 3.3 --- Results and discussion --- p.65 / Chapter 3.3.1 --- Demonstration of the micro dispensing systems --- p.65 / Chapter 3.3.2 --- Protein crystallization screening results --- p.69 / Chapter 3.3.3 --- Protein crystallization in droplets --- p.73 / Chapter 3.3.4 --- Protein crystallization in w/o/w double emulsions --- p.77 / Chapter 3.4 --- Conclusions --- p.80 / Appendix --- p.82 / References --- p.87

Typescript, etc. / Digitized by Kansas Correctional Industries

Digitized by Kansas Correctional Industries

Digitized by Kansas Correctional Industries

Qi Chang. / "March 2002." / Thesis (Ph.D.)--Chinese University of Hong Kong, 2002. / Includes bibliographical references (p. 173-192). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Mode of access: World Wide Web. / Abstracts in English and Chinese.

by Lam Suet Ling. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1997. / Includes bibliographical references (leaves 109-121). / Acknowledgements --- p.i / Table of contents --- p.ii / Abstract --- p.vii / List of Abbreviations --- p.ix / List of Tables --- p.x / List of Figures --- p.xi / Chapter Chapter 1 --- Introduction --- p.1 / Chapter 1.1 --- Ribosome-inactivating proteins (RIPs) --- p.3 / Chapter 1.1.1 --- Types of RIPs --- p.4 / Chapter 1.1.1.1 --- Type I RIPs --- p.5 / Chapter 1.1.1.2 --- Type II RIPs --- p.7 / Chapter 1.1.2 --- Physicochemical properties --- p.7 / Chapter 1.1.3 --- N-glycosidase activity of RIPs --- p.8 / Chapter 1.1.3.1 --- Specificity of N-glycosidase activity --- p.10 / Chapter 1.1.3.2 --- Inhibition of protein synthesis --- p.11 / Chapter 1.1.4 --- Other enzymatic and biological activities of RIPs --- p.11 / Chapter 1.1.4.1 --- Enzymatic activities --- p.11 / Chapter 1.1.4.2 --- Multiple depurination --- p.13 / Chapter 1.1.4.3 --- RNase activity --- p.14 / Chapter 1.1.4.4 --- DNase activity --- p.15 / Chapter 1.1.4.5 --- Biological activities --- p.16 / Chapter 1.1.5 --- Storage of RIPs in plant cells --- p.17 / Chapter 1.1.5.1 --- RIPs targeted to subcellular compartments --- p.18 / Chapter 1.1.5.2 --- Cytoplasmic RIPs --- p.20 / Chapter 1.1.6 --- Physiological roles of RIPs --- p.22 / Chapter 1.1.6.1 --- Defensive role in plants --- p.22 / Chapter 1.1.6.2 --- Metabolic role of RIPs --- p.26 / Chapter 1.1.6.3 --- RIPs as storage proteins --- p.26 / Chapter 1.1.7 --- Application of RIPs --- p.27 / Chapter 1.1.7.1 --- Therapeutic applications --- p.27 / Chapter 1.1.7.2 --- Possible use of RIPs in agriculture --- p.30 / Chapter 1.2 --- Objectives of the present study --- p.31 / Chapter 1.2.1 --- Rationale of the study --- p.31 / Chapter 1.2.2 --- Outline of the thesis --- p.32 / Chapter Chapter 2 --- Screening of hitherto unexplored plant species for RIPs --- p.33 / Chapter 2.1 --- Introduction --- p.34 / Chapter 2.2 --- Materials and methods / Chapter 2.2.1 --- Materials --- p.36 / Chapter 2.2.2 --- Preparation of crude powder --- p.36 / Chapter 2.2.3 --- Protein determination --- p.38 / Chapter 2.2.4 --- Preparation of rabbit reticulocyte lysate --- p.38 / Chapter 2.2.5 --- Protein synthesis inhibition assay --- p.39 / Chapter 2.3 --- Results / Chapter 2.3.1 --- Preparation of crude powder --- p.41 / Chapter 2.3.2 --- Protein synthesis inhibition assay --- p.41 / Chapter 2.4 --- Discussion --- p.43 / Chapter Chapter 3 --- Purification of RIP from garden pea (Pisum sativum) --- p.45 / Chapter 3.1 --- Introduction --- p.46 / Chapter 3.2 --- Materials and methods / Chapter 3.2.1 --- Materials --- p.50 / Chapter 3.2.2 --- Purification of RIP from garden pea --- p.52 / Chapter 3.2.3 --- Sodium Dodecyl Sulfate-Polyacrylamide Gel Electrophoresis (SDS-PAGE) --- p.54 / Chapter 3.2.4 --- Precautions for working with RNA --- p.56 / Chapter 3.2.5 --- N-glycosidase assay --- p.57 / Chapter 3.2.6 --- Quantitation of RNA --- p.60 / Chapter 3.3 --- Results / Chapter 3.3.1 --- Quantitation of RNA --- p.61 / Chapter 3.3.2 --- Affinity chromatography on Affi-gel Blue gel --- p.61 / Chapter 3.3.3 --- Iminodiacetic acid-agarose chromatography --- p.64 / Chapter 3.3.4 --- Cation exchange chromatography on Resource-S --- p.66 / Chapter 3.3.5 --- Gel filtration on Superose 12 HR 10/30 --- p.69 / Chapter 3.3.6 --- "Assessment of purity, yield and activity" --- p.72 / Chapter 3.4 --- Discussion --- p.74 / Chapter Chapter 4 --- Physicochemical and biological properties of garden pea RIP --- p.77 / Chapter 4.1 --- Introduction --- p.79 / Chapter 4.2 --- Materials and methods / Chapter 4.2.1 --- Materials --- p.81 / Chapter 4.2.2 --- Molecular weight determination --- p.82 / Chapter 4.2.3 --- Subunit composition --- p.82 / Chapter 4.2.4 --- Isoelectric focusing (IEF) --- p.83 / Chapter 4.2.5 --- Detection of glycoproteins --- p.84 / Chapter 4.2.6 --- N-terminal amino acid sequence --- p.84 / Chapter 4.2.7 --- Inhibition of cell-free protein synthesis --- p.86 / Chapter 4.2.8 --- N-glycosidase activity --- p.86 / Chapter 4.2.9 --- Deoxyribonuclease activity --- p.87 / Chapter 4.2.10 --- Activity towards tRNA --- p.88 / Chapter 4.3 --- Results / Chapter 4.3.1 --- Molecular weight determination --- p.89 / Chapter 4.3.2 --- Subunit composition --- p.91 / Chapter 4.3.3 --- Isoelectric focusing (IEF) --- p.92 / Chapter 4.3.4 --- Detection of glycoproteins --- p.94 / Chapter 4.3.5 --- N-terminal amino acid sequence --- p.96 / Chapter 4.3.6 --- Inhibition of cell-free protein synthesis --- p.97 / Chapter 4.3.7 --- N-glycosidase activity --- p.99 / Chapter 4.3.8 --- Deoxyribonuclease activity --- p.101 / Chapter 4.3.9 --- Activity towards tRNA --- p.102 / Chapter 4.4 --- Discussion --- p.103 / Chapter Chapter 5 --- General discussion and conclusion --- p.106 / References --- p.109

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