ABSTRACT As far back as the early 1900?s when it was discovered that water could be a mode of transmitting diseases, chlorine was used to disinfect water. In the 1970?s, the formation of disinfection by-products (DBPs) from the reaction of chlorine with natural organic matter was discovered. Since then there have been various studies on alternative disinfectants that could inactivate microorganisms and at the same time form less or no disinfection by-products. More recently the ultraviolet (UV) irradiation has been used to both disinfect and remove organic contaminants in drinking water. Though the use of UV irradiation has been found to be very effective in the inactivation of microorganisms, it does not provide a residual effect to maintain the water?s microbial quality in the distribution system. Due to this, a secondary disinfectant such as chlorine has to be used to achieve microbial stability, suggesting that the formation of chlorination disinfection by-products would still occur but perhaps in different quantities and with different chemical species. In this research, the use of factorial experiments and single factor experiments were used to determine the effects of pH, alkalinity and UV-fluence (dose) on the formation of three classes of disinfection by-products; haloacetic acids (HAAs), haloacetonitriles (HANs) and trihalomethanes (THMs). These disinfection by-products were measured in water samples following post-UV chlorination and the UV treatment was either UV photolysis or UV/H₂O₂. From the factorial experiment results, treatment of synthetic water with UV/H₂O₂, an advanced oxidation process (AOP), produced fewer post-UV chlorination disinfection by-products (PCDBPs) than UV photolysis. For chlorinated PCDBPs, the percentage difference between UV photolysis and UV/H₂O₂ was 55, 65 and 38% for total HAAs (HAA₉), total HANs (THANs) and total THMs (TTHMs) respectively. The percentage difference between UV photolysis and UV/H₂O₂ for brominated PCDBPs was 41 and 42% for HAA9 and TTHMs respectively. Both the use of pH and alkalinity proved to be factors that were significant in affecting the yields of the PCDBPs studied. Increases in alkalinity were found to increase the formation of PCDBPs in the treatment of synthetic water with UV/H₂O₂. Alkalinity had the opposite effect for PCDBP formed under UV photolysis conditions. Increases in pH always decreased the formation of PCDBPs. In the single factor experiments, haloacetic acid concentrations were unaffected as alkalinity was increased but dichloroacetonitrile and chloroform increased in concentration under treatment conditions of UV photolysis followed by chlorination. The UV/H₂O₂ treatment resulted in a decrease in concentration of the PCDBPs. In the pH studies, water samples were subjected only to the UV/H₂O₂ treatments and a reduction in concentration of PCDBPs occurred between pH 7 and 9.

ABSTRACT As far back as the early 1900?s when it was discovered that water could be a mode of transmitting diseases, chlorine was used to disinfect water. In the 1970?s, the formation of disinfection by-products (DBPs) from the reaction of chlorine with natural organic matter was discovered. Since then there have been various studies on alternative disinfectants that could inactivate microorganisms and at the same time form less or no disinfection by-products. More recently the ultraviolet (UV) irradiation has been used to both disinfect and remove organic contaminants in drinking water. Though the use of UV irradiation has been found to be very effective in the inactivation of microorganisms, it does not provide a residual effect to maintain the water?s microbial quality in the distribution system. Due to this, a secondary disinfectant such as chlorine has to be used to achieve microbial stability, suggesting that the formation of chlorination disinfection by-products would still occur but perhaps in different quantities and with different chemical species. In this research, the use of factorial experiments and single factor experiments were used to determine the effects of pH, alkalinity and UV-fluence (dose) on the formation of three classes of disinfection by-products; haloacetic acids (HAAs), haloacetonitriles (HANs) and trihalomethanes (THMs). These disinfection by-products were measured in water samples following post-UV chlorination and the UV treatment was either UV photolysis or UV/H₂O₂. From the factorial experiment results, treatment of synthetic water with UV/H₂O₂, an advanced oxidation process (AOP), produced fewer post-UV chlorination disinfection by-products (PCDBPs) than UV photolysis. For chlorinated PCDBPs, the percentage difference between UV photolysis and UV/H₂O₂ was 55, 65 and 38% for total HAAs (HAA₉), total HANs (THANs) and total THMs (TTHMs) respectively. The percentage difference between UV photolysis and UV/H₂O₂ for brominated PCDBPs was 41 and 42% for HAA9 and TTHMs respectively. Both the use of pH and alkalinity proved to be factors that were significant in affecting the yields of the PCDBPs studied. Increases in alkalinity were found to increase the formation of PCDBPs in the treatment of synthetic water with UV/H₂O₂. Alkalinity had the opposite effect for PCDBP formed under UV photolysis conditions. Increases in pH always decreased the formation of PCDBPs. In the single factor experiments, haloacetic acid concentrations were unaffected as alkalinity was increased but dichloroacetonitrile and chloroform increased in concentration under treatment conditions of UV photolysis followed by chlorination. The UV/H₂O₂ treatment resulted in a decrease in concentration of the PCDBPs. In the pH studies, water samples were subjected only to the UV/H₂O₂ treatments and a reduction in concentration of PCDBPs occurred between pH 7 and 9.

Fluorescence techniques are being considered for the detection and identification of bacterial spores. This thesis sets out to empirically characterize the detailed autofluorescence spectroscopic properties of spores and their target molecules. The multiwavelength fluorescence studies from a unique endogenous biomarker, dipicolinic acid (DPA) and its calcium salt (CaDPA) in bacterial spores are found to be useful for fluorescence characterization of spores. A systematic determination of the fluorescence profile of the major chemical components of Bacillus spores and the effect of UV irradiation on them has been performed in dry samples, wet paste and in aqueous solution. The thesis applies reliable tools for accurately describing complex nature of spectral profile from bacterial spores, and for interpreting and identifying their spectral properties. We show that multiwavelength fluorescence technique combined with Principal Component Analysis (PCA) clearly indicates identifiable grouping among dry and wet Bacillus spore species. Differences are also observed between dried, wet and redried spores, indicating the stark effect of hydration on fluorescence fingerprints. The study revealed that changes in fluorescence of spores due to hydration/drying were reversible and supports a recent model of a dynamic and dormant spore structure. The spectra were analysed with PCA, revealing several spectroscopically characteristic features enabling spore species separation. The identified spectral features could be attributed to specific spore chemical components by comparing the spore sample signals with spectra obtained from the target molecules. PCA indicated underlying spectral patterns strongly related to species and the derived components were correlated with the chemical composition of the spore samples. More importantly, we examined and compared the fluorescence of normal spores with a mutant of the same strain whose spores lack DPA. We discovered that the dramatic fluorescence enhancement of Bacillus spores can be caused by UV irradiation in the spectral region of this unique biomarker without any pre treatment. Differences between spectra of spores, spore strains and other biological samples are very marked and are due to the dominance of the dipicolinate features in the spore spectra. This could lead to a cheap, more sensitive, faster and reagentless bacterial spore detector.

Fluorescence techniques are being considered for the detection and identification of bacterial spores. This thesis sets out to empirically characterize the detailed autofluorescence spectroscopic properties of spores and their target molecules. The multiwavelength fluorescence studies from a unique endogenous biomarker, dipicolinic acid (DPA) and its calcium salt (CaDPA) in bacterial spores are found to be useful for fluorescence characterization of spores. A systematic determination of the fluorescence profile of the major chemical components of Bacillus spores and the effect of UV irradiation on them has been performed in dry samples, wet paste and in aqueous solution. The thesis applies reliable tools for accurately describing complex nature of spectral profile from bacterial spores, and for interpreting and identifying their spectral properties. We show that multiwavelength fluorescence technique combined with Principal Component Analysis (PCA) clearly indicates identifiable grouping among dry and wet Bacillus spore species. Differences are also observed between dried, wet and redried spores, indicating the stark effect of hydration on fluorescence fingerprints. The study revealed that changes in fluorescence of spores due to hydration/drying were reversible and supports a recent model of a dynamic and dormant spore structure. The spectra were analysed with PCA, revealing several spectroscopically characteristic features enabling spore species separation. The identified spectral features could be attributed to specific spore chemical components by comparing the spore sample signals with spectra obtained from the target molecules. PCA indicated underlying spectral patterns strongly related to species and the derived components were correlated with the chemical composition of the spore samples. More importantly, we examined and compared the fluorescence of normal spores with a mutant of the same strain whose spores lack DPA. We discovered that the dramatic fluorescence enhancement of Bacillus spores can be caused by UV irradiation in the spectral region of this unique biomarker without any pre treatment. Differences between spectra of spores, spore strains and other biological samples are very marked and are due to the dominance of the dipicolinate features in the spore spectra. This could lead to a cheap, more sensitive, faster and reagentless bacterial spore detector.

Made available in DSpace on 2014-06-11T19:27:21Z (GMT). No. of bitstreams: 0 Previous issue date: 2008-03-20Bitstream added on 2014-06-13T20:35:45Z : No. of bitstreams: 1 pigatto_g_me_sjrp.pdf: 376138 bytes, checksum: 0d3df3ba13a94adf6610c9416261a91c (MD5) / Xanthomonas campestris é uma bactéria fitopatogênica que causa a podridão negra no sistema vascular das plantas da família das cruciferaceaes. Produz um exopolissacarídeo denominado goma xantana, que possui propriedades reológicas únicas sendo utilizada amplamente como agente de suspensão, espessante, emulsionante e estabilizante. É aplicados em indústrias petrolíferas, alimentícias, farmacêuticas, mineração, têxtil, termoquímicas, tintas, cosméticos e produtos agropecuários. O Brasil é um grande produtor mundial de cana de açúcar e álcool etílico. Produtos estes utilizados para a produção de xantana; o primeiro como substrato da fermentação e o segundo para a separação da goma. Apesar de todo esse potencial, o Brasil importa grande quantidade de goma xantana que poderá ser produzida com grande competitividade internacional. Portanto, este trabalho objetivou a utilização da técnica de irradiação ultravioleta, em uma linhagem específica de Xanthomonas campestris, para a obtenção de mutantes estáveis que possam melhorar o rendimento e/ou qualidade de goma obtida. A quantificação foi realizada através da determinação da biomassa, viscosidade, cálculos do rendimento da biomassa e goma. A irradiação UV por 600 segundos causou uma redução de 92,2% na população irradiada e as linhagens sobreviventes foram isoladas e analisadas nos testes de produção e viscosidade da goma xantana. As linhagens I6, I7, I9 e I10 apresentaram um aumento de 102% na produção de goma comparando com a linhagem não irradiada. Em relação à viscosidade do caldo, as linhagens irradiadas obtiveram um aumento de 48% comparadas com as não irradiadas de 20 e 30 rpm. A viscosidade da solução de goma xantana 1%, também foram superiores quando comparadas com a não irradiada. O aumento de... / Xanthomonas campestris is fitopatogenic bacterium that causes the black rotten in the vascular system of the plants of the family of the cruciferaceaes. It produces an exopolysaccharides that forms the xanthan gum, which is used in ample variety as agent of suspension, thicker, emulsifier and stabilizing, and singular rheological properties. It is applied in petroliferous, nourishing, pharmaceutical industries, of mining, textile, thermo chemistries, inks, cosmetics and farming products. Brazil is the worldwide producing greater of sugar cane of sugar and ethyl alcohol. Products theses used for the xanthan production; the first one as substratum of the fermentation, and the second as for the separation of the gum. Despite all this potential, the Brazil imports lot of xanthan gum that could be produced with great international competitiveness. This aimming work the used of the ultraviolet technique of irradiation in a specific strain of Xanthomonas campestris to obtain the mutants that can improve the income and/or quality of produced gum, through the determination of the biomass, viscosity, calculations of the income of the biomass and gum. The UV irradiation during 60 seconds caused a reduce of the 92.2% in the irradiated strains and the survived strains were isolated and analysed in the tests of production and viscosity of xanthan gum. The strains I6, I7, I9 e I10 showed increased in the xanthan production of 102% comparing with the non-irradiated strain. In relation the viscosity of the broth the irradiated strains the increase of 48% in shear rate of 20 and 30 rpm compared with the no irrdiated. The viscosity of the xanthan solution 1% irradiated were higher also whwn compared with no irradiated in both shear rate (20 and 30 rpm. The increase of viscosity was of 17% to rotational speed of 20 rpm and 16% to 30 rpm. The ...(Complete abstract click electronic access below)

The African bollworm, Helicoverpa armigera (Hübner) (Lepidoptera: Noctuidae), is a polyphagous pest that attacks many crops in sub-Saharan Africa. The pest is currently managed through chemical control, and by planting Bt-transgenic cotton. Trichogrammatoidea lutea Girault (Hymenoptera: Trichogrammatidae) is an indigenous egg parasitoid of H. armigera in southern Africa. The study was undertaken to determine the potential of T. lutea as a biological control agent for augmentative releases as an alternative to chemical control, and to pave the way for the development of a mass-rearing method. The biology of T. lutea was examined in the laboratory on H. armigera, Chilo partellus (Swinhoe), and Cadra (formerly Ephestia) cautella (Walker) (Lepidoptera: Pyralidae). The objectives of the study were to determine (i) the exposure time of UV-irradiation required for killing the embryos of the hosts and the effect of UV-irradiated eggs on life history parameters of T. lutea, (ii) which host(s) and temperature(s) (18, 21, 24, 27, 30 and 35 °C) are suitable for mass-rearing of T. lutea, and (iii) the longevity and age-related reproductive biology of T. lutea on H. armigera. Findings of this study showed that 13 minutes of UV-irradiation were sufficient to kill embryos of all three host species. Life history parameters were not influenced by UV-irradiation but by host species. Parasitism, number of progeny per parasitized egg, proportion of females, and developmental time of T. lutea aried on different host species at temperatures ranging from 18 to 30 °C. Trichogrammatoidea lutea did not develop at 35 °C. Overall parasitism by T. lutea was higher on H. armigera and Cadra cautella compared to Chilo partellus. The number of progeny per parasitized egg was highest on H. armigera compared to Cadra cautella and Chilo partellus. The proportion of females was highest on Chilo partellus, intermediate on Cadra cautella, and lowest on H. armigera. For all species and temperatures tested, parasitism and number of progeny per parasitized egg by T. lutea was highest on H. armigera at 27 °C. The lower threshold for development of T. lutea on all hosts was approximately 12 °C. Female T. lutea parasitized eggs of H. armigera soon after eclosion, with the highest parasitism achieved on the day of eclosion. Though T. lutea parasitized eggs for up to 14 days, it may not be economically viable to keep them in cultures for more than three days since progeny became male biased three days after eclosion. The average longevity of female and male T. lutea was 9 and 6 days, respectively. The life table parameters of T. lutea, the net replacement rate (Ro), mean generation time (T), and instantaneous rate of population increase (rm) were 25.5, 9.79, and 0.33, respectively. The timing of inundative releases of T. lutea must be synchronised with the time that eggs of H. armigera are abundant in the field. The results of this study indicate that T. lutea is a good candidate for further testing for augmentative biological control of H. armigera in the field. If successful, T. lutea may provide opportunities for expanding tactics in the management of H. armigera in southern Africa. Copyright / Dissertation (MSc)--University of Pretoria, 2011. / Zoology and Entomology / unrestricted

Ataxia telangiectasia and Rad3-related protein (ATR) is a serine/threonine-protein kinase of the PI3K family and is well known for its key role in regulating DNA damage responses in the nucleus. In addition to its nuclear functions, ATR also was found to be a substrate of the prolyl isomerase Pin1 in the cytoplasm where Pin1 isomerizes cis ATR at the Ser428-Pro429 motif, leading to formation of trans ATR. Cis ATR is an antiapoptotic protein at mitochondria upon UV damage. Here we report that Pin1’s activity on cis ATR requires the phosphorylation of the S428 residue of ATR and describe the molecular mechanism by which Pin1-mediated ATR isomerization in the cytoplasm is regulated. We identified protein phosphatase 2A (PP2A) as the phosphatase that dephosphorylates Ser428 following DNA damage. The dephosphorylation led to an increased level of the antiapoptotic cis ATR (ATR-H) in the cytoplasm and, thus, its accumulation at mitochondria via binding with tBid. Inhibition or depletion of PP2A promoted the isomerization by Pin1, resulting in a reduction of cis ATR with an increased level of trans ATR. We conclude that PP2A plays an important role in regulating ATR’s anti-apoptotic activity at mitochondria in response to DNA damage. Our results also imply a potential strategy in enhancing cancer therapies via selective moderation of cis ATR levels.

No description available.

This thesis presents the characterization of the optical and mechanical properties of silica nanoparticle films fabricated by ionic self-assembly, also known as layer-by-layer (LbL) deposition. Utilizing electrostatic attraction of oppositely-charged materials permits uniform and rapid growth of the constituents onto planar and curved surfaces. In this work, silica nanoparticles are adsorbed onto glass and polycarbonate substrates, as well as micron-scale glass fibers, with the purpose of improving the optical quality of the respective media. Several methods are presented to improve the adhesion and cohesion of silica nanoparticle films on glass substrates. In the first method, the substrate and nanoparticle surfaces are coated with materials containing sulfonate end groups. Next, a photo-reactive polycation known as diazo-resin (DAR) is used in ISAM deposition with the modified silica nanoparticles. Subsequent exposure to UV converts the ionic bonds between the DAR and sulfonate groups into covalent ones. The second method to improve the mechanical strength is to heat the ISAM silica nanoparticle film at a high enough temperature (500 °C) to remove the polymer and partially fuse the nanoparticles. This technique is known as calcination and is shown to significantly improve the mechanical robustness of the film without compromising the optical properties. The final method involves the deposition of precursor and capping polymer layers around bulk silica nanoparticle films with both bilayer and quadlayer designs. The addition of these polymer layers improves the surface contact between adjacent nanoparticles but reduces the film porosity and consequently the optical transparency. Currently the calcination technique is the only one that significantly improves the film adhesion and cohesion, but suggestions are offered to potentially improve the performance of films made by the other two methods. An alternative way to functionalize polycarbonate substrates for silica nanoparticle ISAM deposition is also presented. The molecular structure of polycarbonate at the surface can be modified by exposing it to deep UV (λ = 185, 254 nm). By doing so, the surface becomes populated with carboxylate species, and thus permits ISAM deposition of poly(allylamine hydrochloride) (PAH) and silica nanoparticles. A variety of spectroscopic methods show that the molecular structure is changed by this procedure, and SEM shows that UV treatment improves the uniformity of ISAM films on polycarbonate. Finally, PAH/silica nanoparticle ISAM films are deposited onto glass fibers. The fibers are used for mechanical reinforcement of polymer composite optical media. The role of the nanoparticle film on the fibers is to reduce light scattering at the interfaces of materials with different thermo-optic coefficients, in other words, transmittance losses associated with changes in temperature. Fiber bundles coated with silica nanoparticles suffer from unacceptable levels of aggregation, and hence do not currently improve the transmittance over the temperature spectrum. Some evidence is presented, however, to suggest that the transparency can be improved if fiber aggregation during ISAM deposition can be avoided. / Ph. D.

Interferentes endócrinos são substâncias que podem causar danos ao meio ambiente e à saúde humana. Estes compostos são usados na produção de vários produtos de uso diário, porém não são completamente eliminados dos efluentes industriais, contribuindo para a contaminação de diversas matrizes ambientais. Nesse contexto, os processos eletroquímicos se destacam com boas eficácias no tratamento de diversos tipos de efluentes. No entanto, uma melhor compreensão do processo é importante para estabelecer tratamentos de efluentes que possam ser mais amplamente aplicados. Esta tese aborda a degradação do metil parabeno (MeP), em diferentes efluentes sintéticos, via eletrólise com ânodos de misturas de óxidos metálicos comercial (MOM-Cl2) e diamante dopado com boro (DDB). Ainda mais importante, o MeP é utilizado como uma molécula modelo para o compreender os efeitos da irradiação de luz UV e de ultrassom (US) durante a eletrólise. É importante lembrar que a composição da matriz deve afetar a eficiência do processo e, assim, também se utiliza o MeP como modelo para entender os possíveis efeitos interferentes de outros compostos orgânicos na sua oxidação. Finalmente, se estuda um efluente simulado da indústria cosmética para melhor compreender os efeitos da eletrólise e da irradiação de US em uma matriz complexa. Foram observadas grandes diferenças entre as eficiências dos tratamentos com MOM-Cl2 e DDB, principalmente com relação ao mecanismo de degradação do MeP. Nos estudos com MOM-Cl2, muitas vezes o efluente final era mais complexo que o inicial, devido à formação de produto sólido, reações de polimerização e alto efeito de interferência quando dois compostos são tratados simultaneamente. Com o DDB, o processo de mineralização é muito mais favorecido, independentemente da complexidade do efluente. O efeito de interferência ganha significância na presença de altas concentrações de um segundo composto orgânico, mas a completa mineralização ainda foi atingida. A irradiação de UV e US representou melhoras no processo de remoção de matéria orgânica, principalmente com relação aos produtos do MeP. Foi observado que surfactantes podem interferir negativamente na degradação de compostos orgânicos devido a formação de micelas. Diante de alto conteúdo micelar a eficiência do processo diminui, porém 90% de mineralização do efluente foi alcançada. A irradiação de US ajuda significativamente no aspecto físico do efluente tratado, sendo possível obter a transformação de emulsões, com alta turbidez e material particulado, em soluções completamente límpidas e mineralizadas. / Endocrine disrupting chemicals (EDCs) are responsible for causing adverse effects on the environment and on human health. Those substances are extensively used in several costumer products, such as pharmaceuticals and cosmetics. However, several EDCs are not completely removed from industrial wastewaters by the most common treatments, contributing on the environmental contamination. In this context, electrochemical processes can be highlighted due to its efficacy presented on the treatment of numerous types of wastewater. Nevertheless, better understanding of the process is important in order to design wastewater treatments that can be widely applied. Hence, this thesis focus on the degradation of methyl paraben (MeP), in different synthetic wastewater, by electrolysis with mixed metal oxides commercial (MMO-Cl2) and boron-doped anode (BDD) anodes. More importantly, MeP is used as a model molecule to understand the effects of the irradiation of UV light and of ultrasound (US) during the electrolysis. It is important to consider that matrix composition must affect the process efficiency. Hence, MeP is also used as model to shed a light on the possible interfering effects of other organics on its oxidation. Finally, a simulated wastewater from cosmetic industry is studied in order to better comprehend the effects of electrolysis and of ultrasound on complex matrix. Great differences were observed on the efficiency of treatments using MMO-Cl2 and BDD, mostly regarding the mechanism of MeP oxidation. With MMO-Cl2, the treated wastewater was often more complex than the initial one, due to the formation of solid product, polymerization reaction and great interfering effect when two compounds are simultaneously treated. Conversely, using BDD, the mineralization process is favored, regardless the complexity of the matrix. Interfering effect on MeP oxidation is relevant under the presence of huge concentrations of a second organic compound, though the complete mineralization is attained. Irradiation of UV and of US resulted in better removals of organic matter, mainly with respect to MeP products. It was observed that surfactants may interfere on the degradation of organic compounds due to the formation of micelles. The efficiency of the process decreases under high micelles content, however 90% of mineralization was achieved. Irradiation of ultrasound notably improves the physical aspect of the treated wastewater, assisting on the transformation of emulsions, with great turbidity and amount of particles, in clear non-organic solutions.