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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

UV-Protective Compounds in Sea Ice-Associated Algae in the Canadian Arctic

Elliott, Ashley 12 1900 (has links)
Marine phytoplankton are known to produce UV-absorbing compounds (UVACs) for protection against UV radiation. To assess whether the same strategy applies to sea ice-associated algal communities, MAAs were measured in algae associated with surface melt ponds, sea ice, sea ice−water interface, and underlying seawater in a coastal bay of the Canadian Arctic Archipelago during the 2011 spring melt transition. Six UVACs were detected as the spring melt progressed, namely shinorine, palythine, and porphyra-334 and three unknowns (U1, U2 and U3). U1 was most likely palythene, another MAA. The molecular identities of the other two UVACs, U2 and U3, which have an absorption maximum of 363 and 300 nm, respectively, remain to be structurally elucidated. The results confirm that Arctic sea ice-associated algal communities are capable of producing photoprotectants and that spatial and temporal variations in MAA and other UVAC synthesis are affected by snow cover and UV radiation exposure. / May 2016
2

Funcionalização de tecidos têxteis com nanopartículas para proteção UV / Functionalization of textile fabrics with nanoparticles for UV protection

Roman Mendoza, Luz Esmeralda 06 June 2018 (has links)
Nos últimos anos no Brasil, instituições como o Instituto Nacional de Câncer José Alencar Gomes da Silva e o Ministério da Saúde, reportaram o aumento de casos de câncer de pele. O câncer de pele é uma das doenças mais comuns a nível mundial e pode estar relacionado à exposição à radiação ultravioleta (UV). O objetivo do presente trabalho foi realizar a funcionalização de tecidos sarja 100% algodão com nanopartículas (NPs) de óxido de zinco (ZnO), as quais possuem propriedades para aplicação como protetor solar, melhorando desta forma as características de proteção à radiação UV do algodão. As NPs de ZnO foram sintetizadas pelo processo de precipitação, empregando nitrato de zinco hexahidratado (Zn(NO3)2.6H2O) e hidróxido de sódio (NaOH). A síntese in situ das NPs de ZnO sobre os tecidos foi realizada por meio do processo de esgotamento, usando o equipamento de tingimento têxtil HT (High Temperature). Para este processo foram utilizadas diferentes concentrações de Zn(NO3)2.6H2O (2, 5, 8 e 10% sobre a massa do tecido) e NaOH (0,7; 1,6; 2,5 e 3,0 g/L), respectivamente. A avaliação do fator de proteção UV (FPU) e os testes de resistência à lavagem dos tecidos foram realizados segundo normas as AATCC 183:2004 e AATCC 61:1996, respectivamente. Foram promovidas também aplicações de resinas têxteis comerciais sobre os tecidos funcionalizados e determinação das propriedades físicas. Além disso, foram realizadas caracterizações de vibração molecular, estruturais e morfológicas das NPs de ZnO e para os tecidos funcionalizados foram efetuadas caracterizações estruturais, morfológicas e térmicas. Os resultados mostraram que tanto as NPs de ZnO como as sintetizadas in situ sobre os tecidos apresentaram estrutura cristalina hexagonal wurtzite. As NPs de ZnO mostraram uma morfologia de estrela com pontas muito protuberantes enquanto que as NPs sintetizadas no tecido apresentaram morfologia similar, mas com pontas pequenas. Para todas as concentrações de nitrato de zinco estudadas, antes e após as 20 lavagens, o FPU dos tecidos funcionalizados com NPs de ZnO tiveram categoria de proteção UV entre boa e excelente / In Brazil, institutions such as the José Alencar Gomes da Silva National Cancer Institute (INCA) and the Brazilian Ministry of Health reported increase and appearance of new types of cancer in recent years. Skin cancer is the most common type of disease worldwide and generally might be related to the exposure of the skin to ultraviolet (UV) radiation generated by the sun. The objective of this work was to perform the functionalization of 100% cotton woven fabrics with zinc oxide (ZnO) nanoparticles (NPs), which has interesting properties for applications as solar protector, thus improving the protection characteristics of cotton against UV radiation. ZnO NPs were synthesized by the precipitation process using zinc nitrate hexahydrate (Zn(NO3)2.6H2O) and sodium hydroxide (NaOH). In situ synthesis of ZnO NPs onto the fabric was carried out via exhaust dyeing method, using the textile High Temperature (HT) dyeing machine. For this process, different concentrations of Zn(NO3)2.6H2O (2, 5, 8 and 10% on the weight of fabric) and NaOH (0.7, 1.6, 2.5 and 3.0 g/L) were used. The evaluation of UV protection factor (UPF) and wash durability tests were performed according to AATCC 183:2004 and AATCC 61:1996 standards, respectively. Commercial textile resins applications onto functionalized fabrics and determination of physical properties were also performed. In addition, molecular, structural and morphological characterizations of ZnO NPs were carried out and structural, morphological and thermal analyzes were performed for functionalized fabric. The results showed that both ZnO NPs and those in situ synthesized onto the fabric, exhibited wurtzite hexagonal crystalline structure. The ZnO NPs displayed a star-like morphology with very pronounce tips, while the NPs onto the fabric had a similar morphology but with small tips. For all concentrations of zinc nitrate studied, before and after 20 cycles washing, the UPF of cotton fabrics functionalized with ZnO NPs had an UV-protection category between good to excellent
3

Funcionalização de tecidos têxteis com nanopartículas para proteção UV / Functionalization of textile fabrics with nanoparticles for UV protection

Luz Esmeralda Roman Mendoza 06 June 2018 (has links)
Nos últimos anos no Brasil, instituições como o Instituto Nacional de Câncer José Alencar Gomes da Silva e o Ministério da Saúde, reportaram o aumento de casos de câncer de pele. O câncer de pele é uma das doenças mais comuns a nível mundial e pode estar relacionado à exposição à radiação ultravioleta (UV). O objetivo do presente trabalho foi realizar a funcionalização de tecidos sarja 100% algodão com nanopartículas (NPs) de óxido de zinco (ZnO), as quais possuem propriedades para aplicação como protetor solar, melhorando desta forma as características de proteção à radiação UV do algodão. As NPs de ZnO foram sintetizadas pelo processo de precipitação, empregando nitrato de zinco hexahidratado (Zn(NO3)2.6H2O) e hidróxido de sódio (NaOH). A síntese in situ das NPs de ZnO sobre os tecidos foi realizada por meio do processo de esgotamento, usando o equipamento de tingimento têxtil HT (High Temperature). Para este processo foram utilizadas diferentes concentrações de Zn(NO3)2.6H2O (2, 5, 8 e 10% sobre a massa do tecido) e NaOH (0,7; 1,6; 2,5 e 3,0 g/L), respectivamente. A avaliação do fator de proteção UV (FPU) e os testes de resistência à lavagem dos tecidos foram realizados segundo normas as AATCC 183:2004 e AATCC 61:1996, respectivamente. Foram promovidas também aplicações de resinas têxteis comerciais sobre os tecidos funcionalizados e determinação das propriedades físicas. Além disso, foram realizadas caracterizações de vibração molecular, estruturais e morfológicas das NPs de ZnO e para os tecidos funcionalizados foram efetuadas caracterizações estruturais, morfológicas e térmicas. Os resultados mostraram que tanto as NPs de ZnO como as sintetizadas in situ sobre os tecidos apresentaram estrutura cristalina hexagonal wurtzite. As NPs de ZnO mostraram uma morfologia de estrela com pontas muito protuberantes enquanto que as NPs sintetizadas no tecido apresentaram morfologia similar, mas com pontas pequenas. Para todas as concentrações de nitrato de zinco estudadas, antes e após as 20 lavagens, o FPU dos tecidos funcionalizados com NPs de ZnO tiveram categoria de proteção UV entre boa e excelente / In Brazil, institutions such as the José Alencar Gomes da Silva National Cancer Institute (INCA) and the Brazilian Ministry of Health reported increase and appearance of new types of cancer in recent years. Skin cancer is the most common type of disease worldwide and generally might be related to the exposure of the skin to ultraviolet (UV) radiation generated by the sun. The objective of this work was to perform the functionalization of 100% cotton woven fabrics with zinc oxide (ZnO) nanoparticles (NPs), which has interesting properties for applications as solar protector, thus improving the protection characteristics of cotton against UV radiation. ZnO NPs were synthesized by the precipitation process using zinc nitrate hexahydrate (Zn(NO3)2.6H2O) and sodium hydroxide (NaOH). In situ synthesis of ZnO NPs onto the fabric was carried out via exhaust dyeing method, using the textile High Temperature (HT) dyeing machine. For this process, different concentrations of Zn(NO3)2.6H2O (2, 5, 8 and 10% on the weight of fabric) and NaOH (0.7, 1.6, 2.5 and 3.0 g/L) were used. The evaluation of UV protection factor (UPF) and wash durability tests were performed according to AATCC 183:2004 and AATCC 61:1996 standards, respectively. Commercial textile resins applications onto functionalized fabrics and determination of physical properties were also performed. In addition, molecular, structural and morphological characterizations of ZnO NPs were carried out and structural, morphological and thermal analyzes were performed for functionalized fabric. The results showed that both ZnO NPs and those in situ synthesized onto the fabric, exhibited wurtzite hexagonal crystalline structure. The ZnO NPs displayed a star-like morphology with very pronounce tips, while the NPs onto the fabric had a similar morphology but with small tips. For all concentrations of zinc nitrate studied, before and after 20 cycles washing, the UPF of cotton fabrics functionalized with ZnO NPs had an UV-protection category between good to excellent
4

Ermittlung des Wissensstandes über Schutzmaßnahmen gegen solare Exposition in Mitgliedsbetrieben als Grundlage für die präventive Tätigkeit der BG ETEM

Braun, Gunnar Johannes 12 April 2018 (has links) (PDF)
In dieser Masterthesis wird erforscht wie der jetzige Kenntnisstand der Sicherheitsfachkräfte zu den Themen solare Exposition, Schutzmaßnahmen und die Akzeptanz der Schutzmaßnahmen durch die Mitarbeiter in den Mitgliedsbetrieben der BG ETEM ist. Diese Themen gewinnen an Bedeutung seit die Berufskrankheit Nummer 5103 in den Anhang 1 der Berufskrankheitenverordnung aufgenommen wurde und die BG ETEM nun für ihre Versicherten auch diesbezüglich präventiv tätig ist. Im Rahmen dieser Masterthesis wurde für die Erforschung des Kenntnisstands ein Fragebogen mit zugehörigem Interviewleitfaden selbst entwickelt. Die anschließenden Befragungen wurden durch den Ersteller in den teilnehmenden Unternehmen persönlich für die Masterthesis vorgenommen. Der Teilnehmerkreis beschränkt sich auf interne Sicherheitsfachkräfte, die in Unternehmen der Branche Energie- und Wasserwirtschaft beschäftigt sind. Erforscht werden neben allgemeinen und betrieblichen Angaben ihr Kenntnisstand zu den Themengebieten Gefährdungsbewusstsein, Gefährdungsbeurteilung, Schutzmaßnahmen und der Informations- und Fortbildungsbedarf. Die Antworten werden mit den eigenen Erwartungen verglichen und Rückschlüsse daraus gezogen. Für die BG ETEM werden die Ergebnisse dieser Masterthesis im Hinblick auf den Präventionsauftrag analysiert. Hierzu werden im Rahmen der Masterthesis auch Vorschläge zu diesen Maßnahmen gemacht. So sollen die Beratungen, Informationsmaterialien und Fortbildungen auf die Präferenzen sowie die vorhandenen Wissenslücken in den Unternehmen zugeschnitten werden, um hier berufsbedingte Neuerkrankungen durch solare Exposition langfristig weitgehend zu verhindern.
5

Surface modification of wood using nano-sized titania particles coated by liquid-precursor flame spray pyrolysis

Sedhain, Ganesh 12 May 2023 (has links) (PDF)
Wood is a renewable resource and versatile material used in tasks ranging from tools and furniture to advanced engineering structures. Although wood is light, mechanically robust, environmentally friendly, and abundant, some inherent properties of wood, such as degradation due to moisture and UV radiation from sunlight, are less desirable for extended service life and dimensional stability. In this dissertation, a novel surface modification of wood is explored by depositing nano-sized titania particles on wood veneers and cross-laminated timber (CLT) blocks by liquid-precursor flame spray pyrolysis to confer reversible wettability switching and enhanced durability to UV irradiation. The reaction between a flame source and a titanium precursor in isopropyl alcohol under controlled air pressure created a micrometer-scale thin TiO2 coating on wood that turns the treated wood superhydrophobic with a water contact angle (WCA) of >=150°. Morphological studies suggest the coating is comprised of sub-100 nm TiO2 individual and aggregated particles, creating a very porous microstructure. The coating consists of TiO2 rich in the anatase phase (>60%) with an average crystal size of 18 and 32 nm for the anatase and rutile phases, respectively. The wettability switching characteristics of the surface of TiO2-wood veneers from superhydrophobicity to superhydrophilicity (WCA ~0°) and again back to superhydrophobicity are examined through UV exposure (0.0032 W/m2), WCA measurements, and vacuum drying at ~0.14 mbar. The color and gloss spectrometry results of the TiO2-treated CLT samples indicate that the coating offered better resistance to discoloration and gloss change than the uncoated samples during the 8-week accelerated weathering conditions. The data shows that the FSP-treated CLT samples were more than two times more effective in preventing discoloration and changes in natural luster, as evidenced by the significant differences in L*, a*, b*, and gloss values. Moreover, the FSP treatment might have played a role in preventing weathering defects, such as splits and cracks. In addition, the FSP-treated CLT specimens were able to reduce variability in the samples more effectively than the control group. Overall, the findings of the study indicate that liquid-precursor FSP has the potential to serve as a facile, economically viable, and less energy-intensive approach to modify wooden surfaces for improved hydrophobicity, as well as to provide shielding against the deteriorating impacts of UV radiation and moisture exposure. Keywords: wood modification, flame spray pyrolysis, titania coating, superhydrophobic coating, particle deposition, wettability switching
6

Optical active thin films on cover glass increasing the efficiency of photovoltaic modules.

Johansson, Wilhelm January 2018 (has links)
Thin film coatings of ZnO, TiO2, CeOX and BiOX have been deposited on soda lime silica glass through spray pyrolysis. The effects on the optical properties of the coated glass, as well as the possible impacts on the life expectancy and energy efficiency of PV-modules have been studied. ZnO and TiO2 coatings both reduced the transmission of UV radiation of wavelengths destructive to PV-modules. Therefore, both have the potential to increase the life expectancy of PV-modules if used on cover glass. The ZnO thin film also showed an increase in photoluminescence at 377 nm when radiated with UV radiation of 325 nm while TiO2 reduced the photoluminescence. ZnO coatings on the cover glass have the potential to increase the efficiency of PV-modules in addition to UV protection. No CeOX or BiOX films were found to be deposited with the method used. The ZnO and TiO2 coated samples showed a decrease in transmission of light, due to increased reflection and possibly scattering. This needs to be addressed if these kinds of coatings are going to be beneficial for Si PV-modules.
7

Ermittlung des Wissensstandes über Schutzmaßnahmen gegen solare Exposition in Mitgliedsbetrieben als Grundlage für die präventive Tätigkeit der BG ETEM

Braun, Gunnar Johannes 07 September 2017 (has links)
In dieser Masterthesis wird erforscht wie der jetzige Kenntnisstand der Sicherheitsfachkräfte zu den Themen solare Exposition, Schutzmaßnahmen und die Akzeptanz der Schutzmaßnahmen durch die Mitarbeiter in den Mitgliedsbetrieben der BG ETEM ist. Diese Themen gewinnen an Bedeutung seit die Berufskrankheit Nummer 5103 in den Anhang 1 der Berufskrankheitenverordnung aufgenommen wurde und die BG ETEM nun für ihre Versicherten auch diesbezüglich präventiv tätig ist. Im Rahmen dieser Masterthesis wurde für die Erforschung des Kenntnisstands ein Fragebogen mit zugehörigem Interviewleitfaden selbst entwickelt. Die anschließenden Befragungen wurden durch den Ersteller in den teilnehmenden Unternehmen persönlich für die Masterthesis vorgenommen. Der Teilnehmerkreis beschränkt sich auf interne Sicherheitsfachkräfte, die in Unternehmen der Branche Energie- und Wasserwirtschaft beschäftigt sind. Erforscht werden neben allgemeinen und betrieblichen Angaben ihr Kenntnisstand zu den Themengebieten Gefährdungsbewusstsein, Gefährdungsbeurteilung, Schutzmaßnahmen und der Informations- und Fortbildungsbedarf. Die Antworten werden mit den eigenen Erwartungen verglichen und Rückschlüsse daraus gezogen. Für die BG ETEM werden die Ergebnisse dieser Masterthesis im Hinblick auf den Präventionsauftrag analysiert. Hierzu werden im Rahmen der Masterthesis auch Vorschläge zu diesen Maßnahmen gemacht. So sollen die Beratungen, Informationsmaterialien und Fortbildungen auf die Präferenzen sowie die vorhandenen Wissenslücken in den Unternehmen zugeschnitten werden, um hier berufsbedingte Neuerkrankungen durch solare Exposition langfristig weitgehend zu verhindern.

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