It was demonstrated for the first time that RAFT polymerizations of NIPAAm can be carried out directly in water at room temperature without photo initiator under UV radiation. Under these conditions, the controlled/living features could be proven for a large range of monomer/RAFT agent ratios. Moreover, even at a monomer conversion exceeding 80%, polymerization control (PDI<1.2) is maintained. It is also demonstrated that the RAFT polymerization of AA can be carried out without photo initiator in water at ambient temperature in the presence of TRITT at short wavelength. At these wavelengths, the controlled/ living characteristics is maintained even at a monomer to polymer conversions exceeding 80%. UV/Vis spectrometry was employed to monitor the functional group (-S(C=S)S-) changes of the employed trithiocarbonate RAFT agent S,S???-Bis(??,?????-dimethyl-acetic acid)-trithiocarbonate (TRITT) in aqueous solution when exposed to UV radiation. It is shown that the degradation pattern of TRITT alone as well as TRITT in the presence of NIPAAm deviate from each other. Surprisingly, it is found that TRITT completely decomposed at 254 nm while the addition of monomer prevented the decomposition of TRITT at the same wavelength. Nuclear magnetic resonance (NMR) techniques were applied to study the decomposition products of TRITT in solution without the addition of monomer. Methanol-d4 was selected as the solvent. In addition, high-resolution soft ionization mass spectrometry techniques were used to map the product species generated during UV radiation induced RAFT polymerizations of NIPAAm and AA in aqueous media, allowing for the tentative assignment of end groups. The NMR analysis suggests that the decomposition of TRITT in methanol-d4 under UV radiation has three cleavage patterns. These three cleavage patterns (described in the current thesis in detail) all occur at the ???S(C=S)S- group, which is the weakest structural unit in TRITT molecule. iii However, polymerization occurs prior to decomposition, if monomer is present. The mass spectrometric analysis suggests that the initial radicals result from the dissociation of TRITT, as well as monomer. Trithiocarbonate end group degradation leading to the formation of thiol terminated chains is also occurring. In the case of NIPAAm polymerization, a peak which may be associated with a cross termination product of the intermediate radical was observed under both 302 nm and 254 nm wavelength irradiation. Interestingly, this peak does not occur in AA polymerization at any wavelength (nor is it expected to form under conventional RAFT conditions and was not observed in previous mass spectrometry studies in thermal or ??-initiated polymerizations of NIPPAm with TRITT) and thus this assignment should be treated as very tentative only.

Ultraviolet radiation reaching the Earth’s surface (UVR, 280-400 nm) may penetrate deep into the clear oligotrophic waters influencing a large part of the euphotic layer. Marine heterotrophic bacteria at the surface of the oceans are especially sensitive to the damaging solar radiation due to their haploid genome with little or no functional redundancy and lack of protective pigmentation. In a context of climate change and ozone depletion, it is clearly important to understand the physiology and underlying molecular UVR responses of abundant marine bacteria species. We chose the marine ultramicrobacterium Sphingopyxis alaskensis as a reference species to study the impact of solar radiation due to its numerical abundance in oligotrophic waters and its photoresistance, previously reported. For this purpose, we focused on the formation of the two major UVB-induced DNA photoproducts (CPDs and 6-4PPs) as well as the differential protein expression under solar radiation. We first demonstrated that the GC content of prokaryotic genome had a major effect on the formation of UVB-induced photoproducts, quantified by HPLC-MS/MS. Due to its high GC content, S. alaskensis presented a favoured formation of highly mutagenic cytosine-containing photoproducts and therefore would be more susceptible to UVinduced mutagenesis. By comparing S. alaskensis to another marine bacterium Photobacterium angustum, we observed for the latter strain a remarkable resistance to high UVB doses associated with a decrease in the rate of formation of CPDs explained by a non-conventional activity of photolyase. We also demonstrated that DNA damage in S. alaskensis was markedly modulated by growth temperature and time spent in stationary phase. In order to assess the effects that environmental UV-R had on regulatory networks and pathways of S. alaskensis, and determine how the cell’s physiology was affected, a quantitative proteomics investigation was performed. Changes in proteome were analyzed, with the recent and powerful mass spectrometry based approach using iTRAQ methodology. Approximately, one third of the proteome of S. alaskensis was identified, with 119 statistically and significantly differentially abundant proteins. Cellular processes, pathways and interaction networks were determined and gave us unique insight into the biology of UV response and adaptation of S. alaskensis.

Ultraviolet radiation reaching the Earth’s surface (UVR, 280-400 nm) may penetrate deep into the clear oligotrophic waters influencing a large part of the euphotic layer. Marine heterotrophic bacteria at the surface of the oceans are especially sensitive to the damaging solar radiation due to their haploid genome with little or no functional redundancy and lack of protective pigmentation. In a context of climate change and ozone depletion, it is clearly important to understand the physiology and underlying molecular UVR responses of abundant marine bacteria species. We chose the marine ultramicrobacterium Sphingopyxis alaskensis as a reference species to study the impact of solar radiation due to its numerical abundance in oligotrophic waters and its photoresistance, previously reported. For this purpose, we focused on the formation of the two major UVB-induced DNA photoproducts (CPDs and 6-4PPs) as well as the differential protein expression under solar radiation. We first demonstrated that the GC content of prokaryotic genome had a major effect on the formation of UVB-induced photoproducts, quantified by HPLC-MS/MS. Due to its high GC content, S. alaskensis presented a favoured formation of highly mutagenic cytosine-containing photoproducts and therefore would be more susceptible to UVinduced mutagenesis. By comparing S. alaskensis to another marine bacterium Photobacterium angustum, we observed for the latter strain a remarkable resistance to high UVB doses associated with a decrease in the rate of formation of CPDs explained by a non-conventional activity of photolyase. We also demonstrated that DNA damage in S. alaskensis was markedly modulated by growth temperature and time spent in stationary phase. In order to assess the effects that environmental UV-R had on regulatory networks and pathways of S. alaskensis, and determine how the cell’s physiology was affected, a quantitative proteomics investigation was performed. Changes in proteome were analyzed, with the recent and powerful mass spectrometry based approach using iTRAQ methodology. Approximately, one third of the proteome of S. alaskensis was identified, with 119 statistically and significantly differentially abundant proteins. Cellular processes, pathways and interaction networks were determined and gave us unique insight into the biology of UV response and adaptation of S. alaskensis.

The research from this project has quantified the solar UV environment beneath and surrounding typical local council public shade structures. The effects of changing seasons, atmospheric conditions, structural modifications and surrounding plant life on diffuse UV have been quantified. Strategies to improve current shade structures, so as to significantly reduce the levels of diffuse UV reaching the human body in the shade, have also been developed. For the shade structures used in this research it was found that ultraviolet protection factors ranged from 1.5 to 18.3 for a decreasing solar zenith angle. Correlations have been found relating diffuse erythemal UV to UV in the shade for clear skies and a changing solar zenith angle. The effect of changing atmospheric ozone levels on diffuse erythemal UV levels has been quantified. UV exposures were assessed for a decrease in scattered UV beneath specific shade structures by the use of two types of protection, namely, side-on polycarbonate sheeting and evergreen vegetation. Broadband radiometric and dosimetric measurements conducted in the shade of a scale model shade structure, during summer and winter, showed significant decreases in exposure of up to 65% for summer and 57% for winter when comparing the use and non-use of polycarbonate sheeting. Measurements conducted in the shade of four shade structures, with various amounts of vegetation blocking different sides, showed that adequate amounts and positioning of vegetation decreased the scattered UV in the shade by up to 89% when compared to the shade structure that had no surrounding vegetation. This research shows that major UV reduction could be achieved by the ‘shade creation and design industry’, and that shade guidelines should be updated as soon as possible.

Chemnitz, Techn. Univ., Diss., 2008.

University, Diss., 2001--Bremen.

University, Diss., 2001--Bremen.

Techn. Universiẗat, Diss., 2002--Berlin.

University, Diss., 2005--Jena.

Orientador: Marian Rosaly Davolos / Banca: Sergio Antonio Marques de Lima / Banca: Kassandra Azevedo Tadini / Resumo: A preocupação com a radiação ultra-violeta (UV) do espectro eletromagnético que atinge a superfície terrestre, devido ao aumento do índice de câncer de pele, tem incentivado a pesquisa de produtos para a proteção da pele. Este trabalho tem como objetivo a obtenção e estudo do filtro inorgânico ZnO:Ti4+ com 1, 5, 10, 20, 40, 50% em mol do dopante e a associação dos filtros dopados obtidos com o filtro orgânico 1-(4-terc-butilfenil)-3-(4- metoxifenil)propano-1,3-diona ou butil metoxi dibenzoil metano (bmdm), comercialmente denominado Eusolex 9020. Os filtros dopados foram obtidos pelo método sol-gel, com razão de hidrólise de 0,1 e de 0,01. As amostras foram caracterizadas por espectroscopia de absorção através de medidas de refletância difusa (RD), espectroscopia na região do infravermelho (IV), espectroscopia na região do ultravioleta - visível (UV-Vís), difratometria de raios X (DRX), colorimetria, medidas de potencial zeta, razão UVA/UVB e comprimento de onda crítico foram calculados para conhecer o desempenho dos filtros na região do UVA. Os resultados de DRX indicam a formação da fase ZnO wurtzita para dopagens de até 10%. Acima dessa porcentagem de "dopante", observa-se a formação de fases de titanatos de zinco (Zn2TiO4 e ZnTiO3). Os espectros no IV apresentam bandas referentes à ligação metaloxigênio deslocadas para maiores números de onda com o aumento da quantidade de dopante, devido ao efeito da força de ligação e do tamanho do íon de titânio em relação ao de zinco nas interações metal-oxigênio. Os espectros de RD apresentam deslocamento das bandas para a região do visível. Os filtros dopados obtidos foram, então, associados com o filtro orgânico bmdm. Os filtros associados foram caracterizados pelas mesmas técnicas acima descritas. Nos espectros IV dos filtros... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The concern with UV radiation of the electromagnetic spectrum that reaches the earth's surface has encouraged the research of products for skin protection due to increased rates of skin cancer. This study aims to obtain and study the inorganic filter ZnO:Ti4+ with 1, 5, 10, 20, 40, 50 at% of doping and the association with doped filters developed through organic filter 1 - (4-tert- butyl phenyl) -3 - (4-methoxyphenyl) propane-1 ,3-dione or butyl methoxy dibenzoyl methane (bmdm), trade name Eusolex 9020®. Doped filters were obtained by the sol-gel method, with hydrolysis ratio of 0.1 and 0.01. The samples were characterized by absorption spectroscopy using diffuse reflectance (DR), infrared (IR) spectroscopy, ultraviolet - visible (UV-Vis), X-ray diffraction (XRD), colorimetric and zeta potential measurements. UVA/UVB ratio and critical wavelength were calculated to know the filter's performance in the UVA region. XRD results indicate the ZnO wurtzite phase formation step for doping levels up to 10%. Above this percentage of doping, phases of zinc titanates (Zn2TiO4 and ZnTiO3) we observed. The IR spectra show bands of the metal-oxygen shifted to higher wave numbers and an increasing amount of dopant due to the bond strength and size effects of the titanium ion compared to zinc ion in metaloxygen interactions. The RD spectra show shifts of bands for the visible region. Doped filters were then associated with the bmdm organic filter. The associated filters were characterized by the same techniques just described above. In the IR spectra of the associated filters, there is also the band on the metal-oxygen, splitting and shifting of the band related to the carbonyl group when compared with the free bmdm, that indicates an association between the filters. The absorption bands of doped filters do not cover... (Complete abstract click electronic access below) / Mestre