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Thesis (MTech (Chemistry))--Cape Peninsula University of Technology, 2016. / The synthesis of water soluble CdTe, CdTe/CdSe and CdTe/CdSe/ZnSe nanoparticles (NPs) and their optical, cytotoxicity as well as imaging properties are presented. The synthesis was carried out under ambient conditions in the absence of an inert environment and involved the use of potassium tellurite (K2TeO3) and sodium selenosulphate (Na2SeSO4) as a stable tellurium and selenium precursor respectively, while mercaptopropanoic acid (MPA) was used as capping agents. In this method, the CdTe NPs were prepared by the addition of tellurium source solution to MPA-cadmium complex solution at different pH while keeping other parameters constant. The formation of the shell (CdSe) and multi shell (CdSe/ZnSe) were achieved by adding desired precursors to the growing CdTe core NPs at one hour interval. The temporal evolution of the optical properties and stability of the growing nanocrystals was monitored in detail by varying the refluxing time, pH and storing the NPs under ambient condition for several days. The as-prepared NPs were characterised using UV-Vis absorption and photoluminescence (PL) spectroscopy, transmission electron microscopy (TEM) and high resolution transmission electron microscopy (HRTEM). The formation of the shells was indicated by an immediate change in the colour of the reaction solutions after the addition of the desired precursor and the shift in the absorption wavelength towards red-region. The optical analyses showed an enhancement in the fluorescent intensity after the addition of the shell solution accompanied by red-shifting of the absorption and emission maximum. The stability study revealed an increase in the emission intensity as the ageing days increased. The stability study of the NPs in air at room temperature show highly improved stability of the core-shell NPs than the core. The TEM analysis showed that the materials are small, monodispersed, spherical and highly crystalline. The cytotoxicity of the NPs was investigated on LM 8 and KM-Luc/ GFP cell line using an MTT protocol at different concentrations. The cell viability show significant improvement after the shell formation with CdTe/CdSe/ZnSe core multi shell NPs having the highest cell viability at higher concentration (60 μg/mL). Furthermore a decrease in cytotoxicity is revealed with increase in reaction time, thus NPs prepared at longer (7 h) reaction time showed lower cytotoxicity compared with those prepared at shorter (0.5 h) reaction time. The confocal laser microscope image of the cells after the addition of the as-synthesised NPs confirmed the transfection of the NPs by KM-Luc/GFP cell line, indicating that the NPs have been endocytosis. This study demonstrates the great potential of the as-synthesised core-multi shell nanoparticles for biological and any applications that require efficiency, high fluorescence intensity and stability.

by Wang Yu = 一維納米結構硫化鎘的生長和表面 / 王瑜. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2005. / Includes bibliographical references. / Text in English; abstracts in English and Chinese. / by Wang Yu = Yi wei na mi jie gou liu hua ge de sheng chang he biao mian / Wang Yu. / Acknowledgements --- p.i / Abstract --- p.ii / 摘要 --- p.iii / Table of contents --- p.iv / List of figures --- p.vi / List of tables --- p.ix / Chapter Chapter 1 --- Introduction / Chapter 1.1 --- Background --- p.1-1 / Chapter 1.1.1 --- One-dimensional (1 -D) nanostructures --- p.1-1 / Chapter 1.1.2 --- "Characteristics, properties, and applications of 1 -D nanostructures" --- p.1-1 / Chapter 1.1.3 --- Synthesis and growth mechanisms --- p.1-3 / Chapter 1.1.3.1 --- Vapor-Liquid-Solid (VLS) mechanism --- p.1-4 / Chapter 1.1.3.2 --- Vapor-Solid (VS) mechanism --- p.1-5 / Chapter 1.2 --- II-VI semiconductor nanomaterials --- p.1-5 / Chapter 1.2.1 --- Cadmium sulfide (CdS) --- p.1-6 / Chapter 1.2.1.1 --- Characteristics and potential applications --- p.1-6 / Chapter 1.2.1.2 --- Works performed by others --- p.1-7 / Chapter 1.3 --- Objectives and approaches in this work --- p.1-8 / Chapter 1.4 --- Thesis layout --- p.1-9 / References --- p.1-10 / Figures --- p.1-13 / Tables --- p.1-14 / Chapter Chapter2 --- Methodology and instrumentation / Chapter 2.1 --- Experimental setup --- p.2-1 / Chapter 2.1.1 --- Substrates --- p.2-1 / Chapter 2.1.2 --- Experimental settings --- p.2-2 / Chapter 2.2 --- Growth parameters --- p.2-2 / Chapter 2.3 --- Characterization methods --- p.2-3 / Chapter 2.3.1 --- "Phase, morphology and microstructure analysis" --- p.2-3 / Chapter 2.3.1.1 --- X-ray diffractometry (XRD) --- p.2-3 / Chapter 2.3.1.2 --- Scanning electron microscopy (SEM) --- p.2-4 / Chapter 2.3.1.3 --- Transmission electron microscopy (TEM) --- p.2-4 / Chapter 2.3.1.4 --- High-resolution transmission electron microscopy (HRTEM) / Chapter 2.3.2 --- Cathodoluminescence (CL) --- p.2-5 / Chapter 2.3.2.1 --- Principles of CL --- p.2-5 / Chapter 2.3.2.2 --- Advantages of CL --- p.2-6 / Chapter 2.3.2.3 --- CL settings --- p.2-6 / References --- p.2-7 / Figures --- p.2-8 / Chapter Chapter3 --- Results and discussions part I - Growth of CdS nanobelts / Chapter 3.1 --- Characterization in general --- p.3-1 / Chapter 3.2 --- Morphology and microstructure --- p.3-1 / Chapter 3.2.1 --- Nanobelt with Au droplet at the tip --- p.3-2 / Chapter 3.2.2 --- Nanobelt without Au droplet at the tip --- p.3-2 / Chapter 3.3 --- Effect of Au catalyst --- p.3-3 / Chapter 3.4 --- Growth models --- p.3-3 / Chapter 3.5 --- Samples sintered at different temperatures --- p.3-5 / Chapter 3.6 --- Samples at different deposition zones --- p.3-6 / Chapter 3.7 --- Cathodoluminescence --- p.3-6 / Chapter 3.7.1 --- Blue shift in the deep level emission --- p.3-7 / Chapter 3.7.2 --- Intensity of the emission --- p.3-8 / References --- p.3-10 / Figures --- p.3-11 / Tables --- p.3-24 / Chapter Chapter4 --- Results and discussions part II - Asymmetric growth on the CdS ribbons / Chapter 4.1 --- Surface polarization --- p.4-1 / Chapter 4.2 --- One sided saw-teeth ribbons --- p.4-2 / Chapter 4.3 --- Two-sided comb-like ribbons --- p.4-3 / Chapter 4.4 --- Growth models for the asymmetric growth --- p.4-5 / References --- p.4-7 / Figures --- p.4-8 / Chapter Chapter5 --- Conclusions and future studies / Chapter 5.1 --- Conclusions --- p.5-1 / Chapter 5.2 --- Future studies --- p.5-2 / References --- p.5-4

Semi-insulating, powder samples of Cadmium Telluride (CdTe) have been studied using ������In Time Differential Perturbed Angular Correlation (PAC) Spectroscopy. The samples have been lightly doped (~10���� cm�����) with ������In atoms, which occupy well-defined metal (Cd) lattice sites and act as probes of the local environment. These substitutional donors form a single defect complex in CdTe. This complex has been identified and characterized as a function of temperature. Those indium probes that are not complexed occupy metal lattice sites with no defect in the local vicinity. Samples containing metal vacancy concentrations as large as 500 ppm have been prepared by a high temperature anneal and quench. The defect complex involves the trapping of a cadmium metal vacancy bound to the indium probe. The electric field gradient (EFG) experienced by probe atoms has a coupling constant of V[subscript Q]=61.5(5) MHz and is not axially symmetric, with the asymmetry parameter given by ��=0.16(4). It is believed that this asymmetry results from a relaxation of the chalcogen (Te) atoms adjacent to the metal vacancy, with the tellurium atom shared by the probe atom and the vacancy providing the dominant contribution. The fraction of complexed probe atoms increases as the sample temperature is decreased, and is still increasing at room temperature. Complexed fractions are reproducible on cycling within the temperature range 40 to 200��C. The binding energy of the complex has been measured to be 0.15(2) eV and is independent of metal vacancy concentration, which varies and is dependent on the details of the quench. In rapidly cooled samples, a non-equilibrium number of these defect complexes is observed. This state equilibrates with a time constant of 45(5) hours at 15��C, implying that at least one of the two constituents involved in the complex has a significant diffusion rate at this temperature. Under the assumption that vacancy diffusion mechanisms dominate at this temperature, it is found that the cadmium vacancies overcome an energy barrier of 0.9(1) eV with a jump time of 20(2) minutes in CdTe at 15��C. / Graduation date: 2002

Graduation date: 1994

Thesis (M.Sc.)--York University, 2004. Graduate Programme in Geography. / Typescript. Includes bibliographical references (leaves 98-103). Also available on the Internet. MODE OF ACCESS via web browser by entering the following URL:http://gateway.proquest.com/openurl?url%5Fver=Z39.88-2004&res%5Fdat=xri:pqdiss&rft%5Fval%5Ffmt=info:ofi/fmt:kev:mtx:dissertation&rft%5Fdat=xri:pqdiss:MQ99353

In the mid-1980's until the late 1990's, Lesser Scaup (<i>Aythya affinis</i>)populations in the boreal forest declined and have remained at historical low levels since that time. This has resulted in a population well below conservation goals. Potential causes for this population decline include a reduction in productivity, which could be related to changes in boreal forest habitat, nutritional condition during reproduction, or due to contaminants acquired during migration or wintering. Though several studies have assessed contaminant levels in Lesser Scaup on wintering, staging and migration routes, relatively little data exist from northern boreal forest areas, one of the core breeding habitats of the Lesser Scaup population and where population declines appear to be most severe. To this end,male Lesser Scaup were trapped from sites in the northern boreal forest in 2004 and 2005 to assess trace element contaminant levels. Previous research has shown that trace elements including cadmium and selenium can influence hormonal status in waterfowl. Specifically, a positive relationship between cadmium and corticosterone and a negative correlation between liver selenium and corticosterone have been observed. The purpose of this study was to test the hypothesis that trace element contaminants can influence hormonal status and related physiological functions in male Lesser Scaup, and that interactions between contaminants, physiological variables such as body condition and social status can modify expression of toxic effects. Blood samples were collected from trapped males to assess stress related changes in blood chemistry (corticosterone, testosterone, glucose and thyroxine) and males were then collected for contaminant analysis and assessment of reproductive physiology. The geometric mean levels of kidney cadmium, liver selenium and liver mercury were 9ppm, 4.33 ppm, 1.31 ppm dry weight respectively. Several variables and interactions including pair status, cadmium, selenium, mercury, body condition and body size influenced corticosterone levels. In male Scaup with high cadmium levels, corticosterone was negatively related to liver selenium in birds with good body condition (R2=0.701,n=9, P=0.005) but not in birds with poor body condition (R2=0.033, n=10,P=0.61). Likewise, in birds with high cadmium, a negative association was found between liver mercury and corticosterone in structurally smaller males (R2=0.491,n=10, P=0.024), whereas no such relationship was found in larger males(R2=0.307, n=9, P=0.12). In birds with low cadmium and low mercury, selenium and corticosterone were negatively correlated (R2=0.568, n=10, P=0.012) while no association was found in males with high mercury (R2=0.325, n=10, P=0.085). Unpaired birds had higher corticosterone than in ducks with low cadmium(F1,17=6.70, P=0.023), while there was no difference between groups in ducks with high cadmium. Glucose levels were not influenced by contaminants or other variables in this study (R2=0.551, F21,17=0.99, P=0.51). Thyroxine levels were positively correlated to mercury levels in paired birds (R2=0.485, n=19, P<0.001)but were not related in unpaired birds (R2=0.063, n=20, P=0.28). Thyroxine levels also showed a relationship with date of capture (F1,37=6.77, n=39, P=0.014). Pair status was influenced by body condition and body size (P2 =9.997, df=2, P=0.007)with larger birds being in better condition and larger, while hormone levels and testicular morphology did not appear to influence pair status. Mass of testes (F9,27=0.45, P=0.90) and testosterone concentrations (F10,28=0.31, P=0.10) were not influenced by contaminant levels, body condition or body size. Seminiferous tubule diameter was positively related to testes mass (R2=0.397, n=39, P<0.0001) and negatively related to liver selenium levels (R2=0.123, n=39, P=0.009). To clarify the influence of selenium on corticosterone, captive male Lesser Scaup were fed diets dosed with selenomethionine. Dose groups accumulated different levels of selenium (control group=0.19 ng/ml, 7.5 ppm group=0.74 ng/ml and 15 ppm=1.01 ng/ml) (F2,12=155.12; P<0.001) but this appeared to have no effect on corticosterone levels (Wilks Lambda=0.659, F4,10=1.29, P=0.34) or behavioral patterns (Wilks Lambda=0.659, F4,10=1.294, P=0.34) in captive birds. Results from the field portion of this study support the hypothesis that trace element levels can influence hormonal status in wild Lesser Scaup and that interactions of contaminants and physiological variables can modify expression of toxic effects. Studies such as this one display the complex nature of biological systems and emphasize the importance of considering interactions between different contaminants and other variables to clearly assess their influences on physiology.

Le Cd est un métal hautement toxique, dont les expositions chroniques mènent à des maladies d'obstruction respiratoire, des troubles rénaux ainsi que des désordres osseux. Il est connu que le Cd a pour cible de liaison les groupements thiols des protéines, d'où sa forte affinité au GSH et à la MT. Le Cd peut générer un stress oxydatif possiblement par l'inhibition d'enzymes antioxydantes, telles que la CAT, la SOD, le GR et la GPx, in vitro et in vivo. L'accumulation de Cd au sein des cellules induit la synthèse de MT qui protège des dommages oxydatifs ou de la toxicité des métaux. Sachant que l'exposition au Cd entraîne une induction de Pgp, de récentes études stipulent que la Pgp serait responsable de l'efflux de Cd après surexpression des gènes de MDR. Pour sa part, le Zn est un métal essentiel capable d'induire le GSH, la HSP70, la SOD ainsi que la MT, et ce, sans induire de stress oxydatif. Le but de cette recherche fut de caractériser la différence de sensibilité des cellules alvéolaires (lignée A549) et bronchiolaires (lignée H441) face au Cd et de comparer leur capacité à développer une résistance au Cd suite à une préexposition au Cd ou au Zn. Les hypothèses sont : i) le Cd induit un déséquilibre redox dans les cellules pulmonaires et celles-ci ont des capacités antioxydantes ainsi que des capacités à exprimer des protéines de stress de réponse immédiate différentes et ii) le Zn est en mesure d'induire une résistance au Cd différente de celle induite par le Cd lui-même. Les résultats de viabilité cellulaire obtenus après exposition de 24 h au Cd indiquent une LC50 presque deux fois plus élevée pour les cellules H441 comparativement aux cellules A549 (118 ± 7 vs. 61 ± 6 µM). Cette différence n'est pas due à une différence d'accumulation intracellulaire du Cd, ni au niveau basal de GSH intracellulaire, mais serait possiblement due au niveau d'ARNm de HSP70 (évalué semi quantitativement) 2,4 fois plus élevé dans les cellules H441 que dans les cellules A549. Cependant, les résultats de viabilité cellulaire obtenus en présence de BSO, un inhibiteur de synthèse de GSH, révèlent que cet antioxydant détient un rôle important dans la résistance basale au Cd dans les deux lignées. La CAT semblerait avoir un rôle plus important dans la résistance basale au Cd dans les cellules A549 que dans les cellules H441, compte tenu des résultats obtenus en présence de 3AT, un inhibiteur de la CAT. Dans les deux lignées, une préexposition de 24 h au Cd ou au Zn n'a pas modifié les niveaux d'accumulation de 109Cd. Une préexposition de 24 h au Cd (20 µM) a presque doublé la valeur de LC50 dans les cellules A549 tandis qu'une préexposition de 24 h au Zn (40 µM) n'a induit aucune résistance. Inversement, dans les cellules H441, la préexposition de 24 h au Cd (40 µM) n'a pas eu d'effet, tandis que le Zn (40 µM) a augmenté la résistance au Cd avec une augmentation de 23% de la LC50. Dans les cellules A549, la HSP70 ainsi que la MDR1 ne sembleraient pas être impliquées dans l'induction de résistance au Cd, par le Cd. Malgré que les cellules H441 soient constitutivement plus résistantes au Cd que les cellules A549, les cellules A549 possèdent une meilleure capacité à développer une résistance que les cellules H441. Nos résultats révèlent ainsi des différences entre résistances basales et acquises entre les deux lignées cellulaires et montrent que les cellules A549 et H441 toutes deux d'origine pulmonaire ne réagissent pas de la même façon, ne développent pas les mêmes mécanismes de défense et n'expriment pas nécessairement les mêmes niveaux de protéines de stress. ______________________________________________________________________________ MOTS-CLÉS DE L’AUTEUR : cellules A549, cellules H441, Cadmium, Zinc, tolérance, GSH, MDR1, HSP70, stress oxydatif.

In the mid-1980's until the late 1990's, Lesser Scaup (<i>Aythya affinis</i>)populations in the boreal forest declined and have remained at historical low levels since that time. This has resulted in a population well below conservation goals. Potential causes for this population decline include a reduction in productivity, which could be related to changes in boreal forest habitat, nutritional condition during reproduction, or due to contaminants acquired during migration or wintering. Though several studies have assessed contaminant levels in Lesser Scaup on wintering, staging and migration routes, relatively little data exist from northern boreal forest areas, one of the core breeding habitats of the Lesser Scaup population and where population declines appear to be most severe. To this end,male Lesser Scaup were trapped from sites in the northern boreal forest in 2004 and 2005 to assess trace element contaminant levels. Previous research has shown that trace elements including cadmium and selenium can influence hormonal status in waterfowl. Specifically, a positive relationship between cadmium and corticosterone and a negative correlation between liver selenium and corticosterone have been observed. The purpose of this study was to test the hypothesis that trace element contaminants can influence hormonal status and related physiological functions in male Lesser Scaup, and that interactions between contaminants, physiological variables such as body condition and social status can modify expression of toxic effects. Blood samples were collected from trapped males to assess stress related changes in blood chemistry (corticosterone, testosterone, glucose and thyroxine) and males were then collected for contaminant analysis and assessment of reproductive physiology. The geometric mean levels of kidney cadmium, liver selenium and liver mercury were 9ppm, 4.33 ppm, 1.31 ppm dry weight respectively. Several variables and interactions including pair status, cadmium, selenium, mercury, body condition and body size influenced corticosterone levels. In male Scaup with high cadmium levels, corticosterone was negatively related to liver selenium in birds with good body condition (R2=0.701,n=9, P=0.005) but not in birds with poor body condition (R2=0.033, n=10,P=0.61). Likewise, in birds with high cadmium, a negative association was found between liver mercury and corticosterone in structurally smaller males (R2=0.491,n=10, P=0.024), whereas no such relationship was found in larger males(R2=0.307, n=9, P=0.12). In birds with low cadmium and low mercury, selenium and corticosterone were negatively correlated (R2=0.568, n=10, P=0.012) while no association was found in males with high mercury (R2=0.325, n=10, P=0.085). Unpaired birds had higher corticosterone than in ducks with low cadmium(F1,17=6.70, P=0.023), while there was no difference between groups in ducks with high cadmium. Glucose levels were not influenced by contaminants or other variables in this study (R2=0.551, F21,17=0.99, P=0.51). Thyroxine levels were positively correlated to mercury levels in paired birds (R2=0.485, n=19, P<0.001)but were not related in unpaired birds (R2=0.063, n=20, P=0.28). Thyroxine levels also showed a relationship with date of capture (F1,37=6.77, n=39, P=0.014). Pair status was influenced by body condition and body size (P2 =9.997, df=2, P=0.007)with larger birds being in better condition and larger, while hormone levels and testicular morphology did not appear to influence pair status. Mass of testes (F9,27=0.45, P=0.90) and testosterone concentrations (F10,28=0.31, P=0.10) were not influenced by contaminant levels, body condition or body size. Seminiferous tubule diameter was positively related to testes mass (R2=0.397, n=39, P<0.0001) and negatively related to liver selenium levels (R2=0.123, n=39, P=0.009). To clarify the influence of selenium on corticosterone, captive male Lesser Scaup were fed diets dosed with selenomethionine. Dose groups accumulated different levels of selenium (control group=0.19 ng/ml, 7.5 ppm group=0.74 ng/ml and 15 ppm=1.01 ng/ml) (F2,12=155.12; P<0.001) but this appeared to have no effect on corticosterone levels (Wilks Lambda=0.659, F4,10=1.29, P=0.34) or behavioral patterns (Wilks Lambda=0.659, F4,10=1.294, P=0.34) in captive birds. Results from the field portion of this study support the hypothesis that trace element levels can influence hormonal status in wild Lesser Scaup and that interactions of contaminants and physiological variables can modify expression of toxic effects. Studies such as this one display the complex nature of biological systems and emphasize the importance of considering interactions between different contaminants and other variables to clearly assess their influences on physiology.

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