The objectives of this research programme were to examine the influence of manufacturing and processing parameters on the environmental stability of aqueous acrylic based latices and to also extend the programme to an assessment of the behaviour of various stabiliser types suitable to such materials through either end-group modification or direct in-situ addition. During the research programme a number of physical and chemical techniques were assessed to routinely characterise and monitor the photochemical and thermal degradation of acrylic latices. These were based on emulsion polymerised formulations of methyl methacrylate and butyl acrylate. In the first instance, acrylic latices based on different formulations were chosen as homopolymers and copolymers. Here the nature of impurities and oxidation products generated during various stages of their manufacture have to be characterised and inter-related to their influence on subsequent environmental degradation. This involved the use of reflectance FT-IR spectroscopy to show functional group changes together with colourimetric U.V. analysis to determine photochemical generation of hydroperoxides. The early chemical changes and their subsequent influence on the physical and chemical properties of the latices during the later stages of environmental degradation were found to exhibit a close inter-relationship. In this regard the formation and the manufacturing temperatures and periods were crucial. Thermal methods of analysis were also used to characterise differences in the properties of the latices before and during thermal and photochemical oxidation. The nature of the residual persulphate initiator and the compositions of the latices in terms of end group modification were important parameters. De-esterification and hydroperoxide formation were found to be important processes during latex degradation while the use of low levels of co-monomer addition. such as methacrylic acicL to the emulsion reaction gave latices with improved light stability. Subsequent aspects of the research programme involved a detailed investigation into the behaviour and performance of various stabiliser types and formulations. Thus, while coreactive hindered piperidine stabilisers was found to be effective, the incorporation of simple terminal dialkyl acrylamide/methacrylaroide groups were also found to be effective. The efficiency of dialkylamide groups operating through a sacrificial mechanism is discussed. The influence of these processing operations on subsequent stabiliser activity provides valuable information on the mode of action of these stabilisers in such complex media. Further work involved a study into the effect of fluorinated methacrylates used in emulsion polymerised formulations. Here, the presence of residual starting materials in the monomer was found to have a detrimental effect in terms of photostability. Subsequent analysis of acrylic resins, based on solution polymerised formulations of methyl methacrylate and fluorinated methacrylates, was undertaken. The influence of reactive stabiliser types on these resins was important and to improve stabiliser perfonnance, synergistic stabiliser formulations were studied. This project will provide important fundamental information on the behaviour of active chromophores produced during the manufacturing process and hopefully resuh in the development of monitoring methodologies to establish paint quality.

Tetrachloroethylene (PCE) is a contaminant that has been frequently detected in ground water, surface water, air and soil. Advanced reduction processes (ARP) make up a set of wastewater treatment technologies that have been proposed recently. This project has conducted research on degrading PCE with an ARP that combines dithionite and ultraviolet activation. The purpose of the project is to provide knowledge for the development of potential wastewater treatment technologies. Several control experiments (blank control, reagent control and UV control) were conducted to prove the feasibility of applying the dithionite/UV ARP to degrade PCE. ARP degradation of PCE was studied under different pH (5, 7, 8, 9) and light intensities (2, 4, 7.3 mW/cm2). The results showed that the fastest degradation was observed at pH 7 and that degradation becomes faster at higher light intensities. Combining dithionite and UV light resulted in a faster degradation of PCE than only using UV light to photolyze PCE.

The polymer coatings considered in this thesis work principally by creating a barrier, in order to prevent a corroding medium such as water and / or oxygen from contacting the surface of the underlying metal. Such coatings are subject to attack from the environment in which they are placed. This attack can lead to failure of the coating and corrosion of the underlying metal. In this thesis, three principle means of coating degradation, leading to subsequent corrosion of the substrate have been considered: Mechanical damage of the coating, the effect of ultra-violet light weathering and filiform corrosion. Electrochemical measurements have been made in order to attempt to quantify both the degree of coating breakdown and the extent of corrosion of the substrate. The principle method for measuring coating breakdown and substrate corrosion utilised in the work for this thesis was Electrochemical Impedance Spectroscopy (EIS). EIS, in principle, allows both changes in coating porosity resulting from coating breakdown, and the extent of corrosion of the substrate to be measured. The extent of delamination under polymer coatings on defects of different sizes and on different substrates has been measured. The effect of ultra-violet light weathering of polymer coatings was measured using EIS and correlated with measurements of light reflection of the coating. Filiform corrosion was induced on two different substrates, coated with various coatings. The effect of substrate and coating on filiform corrosion growth rate and mechanism has been considered.

The Cornwall Water Purification Plant collaborated with the University of Toronto to monitor UV-H2O2 treatment performance. This study includes a review of engineering and operational aspects of UV-H2O2 implementation. A number of operational challenges were experienced with retrofitting UV-H2O2 into the existing treatment plant, and an overview of the challenges and solutions faced at Cornwall is given. The project also includes a thorough water quality analysis. Taste and odour (T&O) events have been monitored for three years and the efficiency of UV-H2O2 on T&O removal is reported. Furthermore, little is known about any potential side effects of the treatment on downstream processes, especially secondary disinfection. The impact of UV-H2O2 on natural organic matter alterations, chlorine stability and disinfection by-product formation is reported using results from full-scale water quality monitoring campaigns at Cornwall, combined with laboratory experiments.

The Cornwall Water Purification Plant collaborated with the University of Toronto to monitor UV-H2O2 treatment performance. This study includes a review of engineering and operational aspects of UV-H2O2 implementation. A number of operational challenges were experienced with retrofitting UV-H2O2 into the existing treatment plant, and an overview of the challenges and solutions faced at Cornwall is given. The project also includes a thorough water quality analysis. Taste and odour (T&O) events have been monitored for three years and the efficiency of UV-H2O2 on T&O removal is reported. Furthermore, little is known about any potential side effects of the treatment on downstream processes, especially secondary disinfection. The impact of UV-H2O2 on natural organic matter alterations, chlorine stability and disinfection by-product formation is reported using results from full-scale water quality monitoring campaigns at Cornwall, combined with laboratory experiments.

This study examined the effectiveness of UV radiation in reducing numbers of naturally occurring aerobic psychotrophic bacteria, lactic acid bacteria, Campylobacter and surface inoculated E. coli on split, boneless, skinless chicken breasts and the effects the UV treatments had on the taste of the chicken. The objective of the study was to determine the UV dosage that gave the largest amount of microbial kill without adversely affecting the taste of the chicken. Two groups of 12 breasts were individually vacuum packaged. One group was surface inoculated with 1ml of a 2.0 X 106 CFU/ml culture of generic E. coli. The other group received no inoculation. Two breasts from each group were treated with one of six different UV radiation doses, 0 mW s/cm2 (control-no exposure), 34mW s/cm2, 101mW s/cm2, 202mW s/cm2, 504mW s/cm2 and 1008mW s/cm2. Within 24 hr of the treatments and again after seven days, one breast from each group and each treatment was enumerated for bacterial load. The results showed that bacterial load on the inoculated UV treated breasts were significantly reduced (p <0.05) at every treatment level by an average of 1.5 logs compared to the inoculated controls. There were however, no significant differences (p >0.05) between the inoculated breasts at any of the five different UV treatment dosages. The non-inoculated breasts showed no significant differences in the numbers of bacteria on the controls, as compared to the breasts treated with any of the five UV doses (p >0.05). Another set of 50 breasts were individually vacuum packaged and divided into six groups. Five groups contained five breasts each. Each group was treated with UV doses of 202mW s/cm2, 504mW s/cm2, 1008mW s/cm2, 2016mW s/cm2 and 3024mW s/cm2 respectively. The control group (n=25) received no exposure. Within 48 hr, and again seven days after treatments, triangle tests for difference were conducted to see if the taste of the chicken had been affected by the treatments. A sensory panel detected a significant taste difference between the untreated chicken and chicken treated at 504mW s/cm2 (p <0.05) two days after treatment, and between the control and chicken treated at 2016mW s/cm2 seven days after treatment (p <0.05). / Master of Science

Inorganic UV-filters in use today often occur as nanoparticles and have a photocatalytic effect, which can be a problem since they can cause negative health effects. This is why Upsalite®, a mesoporous magnesium carbonate recently has been investigated as a UV-filter. Upsalite® itself is however not suitable as a UV-filter since it mainly protects in the UVC range and hence it needs to be complemented by other substances. The substance studied to functionalize Upsalite® in this thesis is titanium dioxide which is an inorganic UV-filter commonly used in sunscreens. In this work two different sol-gel synthesis routes of titanium dioxide have been investigated as well as a co-synthesis of Upsalite® and titanium dioxide. In the first synthesis route already synthesized Upsalite® was mixed with titanium tetra-isopropoxide and 1-propanol. The second synthesis route was a modified version of synthesis routes described in literature where methanol solvent was used and the pressure was altered by CO2. This route was explored due to its resemblance with the Upsalite® synthesis. Pressure, temperature and amount of water were varied to optimize incorporation of Upsalite® and investigate possibilities for a co-synthesis. Subsequently a co-synthesis of Upsalite® and titanium dioxide was performed that resulted in two amorphous composite materials depending on if water was added in the drying procedure or not. When mixing Upsalite® in the synthesis liquid of titanium dioxide, titanium dioxide seems to be deposited on Upsalite®. It is however difficult to determine whether the pores of Upsalite® have been completely filled or if they have collapsed. The acid catalyst HCl promotes formation to crystalline titanium dioxide but Upsalite® instead prevents it. The limited crystallization of titanium dioxide when synthesized with Upsalite® may be due to confinement in the Upsalite® pores. The UV-blocking properties of the TiO2-Upsalite® without HCl are good with an sun protection factor (SPF) of 27 for a 10 wt% blend in a lotion and an SPF of 7 for the sample with HCl. The modified synthesis route of TiO2 showed that it is possible to perform a sol-gel synthesis with a considerably lower amount of water than found in literature and that alteration of temperature and pressure during the synthesis does not affect the crystallization temperature noteworthy. The materials obtained from the co-synthesis are slightly porous, probably consisting of one or several magnesium titanium oxides and a carbonate phase and showed a transmission cutoff in between Upsalite® and titanium dioxide corresponding to an SPF of 5.

Le nitrure de bore hexagonal (h-BN) est un semi-conducteur à large bande interdite (~ 6 eV) avec une stabilité thermique et chimique très élevées lui offrant la possibilité d'être utilisé dans des dispositifs fonctionnant dans des conditions de fonctionnements extrêmes. La nature indirecte de la bande interdite dans h-BN a été étudiée à la fois par des calculs théoriques et par des expériences. Un exciton indirect et des recombinaisons assistées par phonons dans h-BN ont été observées par photoluminescence.Durant cette thèse, nous avons étudié les propriétés optiques de cristaux massifs et de couches hétéro-épitaxiales de nitrure de bore hexagonal. Nous avons étudié des échantillons provenant de différentes sources et des cristaux qui ont été fabriqués en utilisant différentes méthodes de croissance pour nous permettre de mesurer les propriétés optiques intrinsèques de h-BN. Nous rapportons l'impact des symétries des phonons sur la réponse optique du h-BN en effectuant des mesures photoluminescence résolues par polarisation. L’analyse des données en polarisation, nous permet de mesurer la contribution du phonon manquant, celui qui n'a pas été détectée avant cette thèse. En suite, nous démontrons que l'origine de la structure fine du spectre de PL provient pour chaque réplique phonon d’une diffusion complémentaire de type Raman faisant intervenir le mode de phonon E2g à basse énergie (mode de cisaillement inter-feuillets). Les spectroscopies de photoluminescence et de diffusion inélastique Raman ont été combinées pour quantifier l'influence des effets isotopiques sur les propriétés optiques de h-BN ainsi pour révéler que les modifications des interactions de van de Waals liées à l'utilisation de 10B et 11B ou du bore naturel pour la croissance de cristaux h-BN massifs.Enfin, nous étudions des epitaxis de h-BN crues par Épitaxie sous Jets Moléculaires. L'utilisation conjointe de l’imagerie par microscopie à force atomique (AFM) et de la spectroscopie de photoluminescence permet de comprendre la première observation de recombinaison assistée par phonons dans des épitaxies de h-BN sur le saphir et le graphite. Ce résultat indique que la croissance de h-BN à large échelle par méthode épitaxiales est en voie d'acquérir la maturité nécessaire au développement technologique de h-BN. / Hexagonal boron nitride (h-BN) is a wide bandgap (~ 6 eV) semiconductor with a very high thermal and chemical stability often used in devices operating under extreme conditions. The indirect nature of the bandgap in h-BN is investigated by both theoretical calculations and experiments. An indirect excion and phonon-assisted reombinations in h-BN are observed in photoluminescene spectroscopy.This thesis focus on the optical properties of bulk and epilayers of h-BN. We investigated samples from different sources grown different methods in order to confirm the intrinsic optical properties of h-BN. We report the impact of the phonon symmetry on the optical response of h-BN by performing polarization-resolved PL measurements. From them, we will measure the contribution of all the phonon-assisted recombination which was not detected before this thesis. We follow by addressing the origin of the fine structure of the phonon-assisted recombinations in h-BN. It arises from overtones involving up to six low-energy interlayer shear phonon modes, with a characteristic energy of about 6.8 meV.Raman and photoluminescence measurements are recorded to quantify the influence of isotope effects on optical properties of h-BN as well as the modifications of van de Waals interactions linked to utilization of 10B and 11B or natural Boron for the growth of bulk h-BN crystals.Finally, we study h-BN thin epilayers grown by Molecular Beam Epitaxy at Nottingham University, atomic force microscopy (AFM) images and photoluminescence features are combined to confirm the first observation of phonon-assisted recombination in high quality thin h-BN epilayers grown on c-plane sapphire and Highly Ordered Pyrolitic Graphite. This demontrates that large scale growth of h-BN by epitaxy is getting a technologically required maturity.

Foram estudadas trinta e uma cepas fúngicas não identificadas, as quais foram denominadasX1 a X31. O potencial fotoprotetor foi avaliado pela medida espectrofotométrica da absorçãodos extratos na região do UV (280-400 nm). Os extratos com os melhores perfis de absorção em cultura estacionária foram X1, X2, X6, X12, X13, X18, X19, X22, X24 e X31 e, em cultura agitada X4 e X17. A reprodutibilidade do processo foi avaliada e as cepas fúngicas que apresentaram coeficiente de variação menor que 15% foram selecionadas para o estudo de fotoestabilidade. A fotoestabilidade dos extratos foi avaliada pela medida da viabilidade celular de fibroblastos L929 tratados com extratos previamente irradiados sob radiação UVA (11,2 J/cm2) e UVB (3,43 J/cm2) e extratos não irradiados, bem como, pela comparação das áreas sob as curvas de absorção na região do UV dos extratos irradiados e não irradiados. Os extratos selecionados para o estudo de fotoestabilidade foram X4, X12, X19, X22, X24 e X31. Os extratos não irradiados apresentaram os seguintes valores deIC50 para viabilidade celular (citotoxidade): X4-130µg/ml, X19-20µg/ml, X22-10 µg/ml e X24-60µg/ml. Após a radiação UVA e UVB, os extratos apresentaram redução significativa da viabilidade celular em relação ao IC50 dos extratos não irradiados. Sob luz UVB, os extratos X12 (IC50 35µg/ml) e X31 (IC50 70µg/ml) mantiveram a mesma porcentagem de redução da viabilidade celular quando comparado ao IC50 dos extratos não irradiados. No entanto após exposição à luz UVA, o extrato X12 aumentou a viabilidade celular de 50% (quando não irradiado) para 75% (irradiado). Enquanto que o extrato X31, mesmo após a radiação UVA, manteve a mesma redução de 50% da viabilidade celular. Nessa etapa os extratos selecionados foram os X12 e X31. O espectro de absorção na região do UV obtido para o extrato X12 mostrou uma redução da absorbância de 28,3% sob radiação UVB e de 60% sob radiação UVA em relação ao extrato não irradiado. O extrato X31 apresentou uma redução da absorbância de 17,6% e30% sob radiação UVB e UVA respectivamente, em relação ao extrato não irradiado. Os fungos selecionados foram identificados por PCR, sugerindo que o fungo X12 seja o Aspergillus terreus e o X31 seja o Talaromyces pinophilus. Por fim, foi feita a identificação da substância ativa do extrato X12 empregando a técnica de desreplicação, a qual fez o uso da instrumentação analítica acoplada UHPLC-DAD-(ESI)-HRMS associada ao banco de dados Chapman& Hall\'s Dictionary of Natural Products (DNP). No extrato X12 o composto majoritário foi identificado como sendo a citreoviridina. Assim, os resultados do presente trabalho permitiu estabelecer um procedimento para a seleção de fungos produtores de compostos absorvedores de radiação UV, que poderia ser aplicado na obtenção de novos filtros orgânicos naturais para protetores solares. / It were studied thirty-one fungal strains not identified, which were named X1 to X31. The photoprotective potential was assessed spectrophotometrically by measuring absorption of the extract in the UV region (280-400 nm). The extracts that presented the best absorption profiles in stationary culture were X1, X2, X6, X12, X13, X18, X19, X22, X24 and X31, and X4 and X17 in stirred culture. The reproducibility of the process was evaluated and fungal strains that showed a coefficient of variation lower than 15% were selected for the study of photostability. The photostability of the extracts was assessed by measuring cell viability of L929 fibroblasts treated with extracts previously irradiated under UVA light (11,2 J/cm2) and UVB (3,43 J/cm2) and not irradiated extracts, as well as by comparison of the areas under the curves of absorption in the UV region of the irradiated and non-irradiated extracts. The extracts selected for the study of photostability were X4, X12, X19, X22, X24 and X31. The non-irradiated extracts showed the following IC50 values for cell viability (cytotoxicity): X4- 130?g/ml X19-20?g/ml, X22-10/ml and X24-60?g/ml. After UVA and UVB radiation, the extracts showed significant reduction in cell viability compared to the IC50 of the unirradiated extracts. Under UVB light, the X12 extracts (IC50 35?g/ml) and X31 (IC50 70mg/ml) maintained the same percentage of cell viability reduction when compared to the IC50 of the unirradiated extracts. However after exposure to UVA light, X12 extract increased the cell viability from 50% (when not irradiated) to 75% (irradiated). While X31 extract even after the UVA irradiation, remained the same 50% of reduction in cell viability. At this stage the selected extracts were X12 and X31. The absorption spectrum in the UV region obtained for X12 extract showed a decrease in absorbance of 28.3% under UVB and 60% under UVA radiation relative to non-irradiated extract. The X31extract showed a reduction in absorbance of 17.6% and 30% in UVA and UVB radiation, respectively, compared to non-irradiated extract. The selected fungi were identified by PCR, suggesting that X12 fungus is Aspergillus terreus and X31 is the Talaromyces pinophilus. Finally it was identified the active substance of X12 extract employing dereplication technique which makes use of coupled analytical instrumentation UHPLC-DAD- (ESI) HRMS associated to the Chapman and Hall\'s Dictionary of Natural Products (DNP) database. The majority compound of X12 extract was identified as the citreoviridin. Thus, the results of this study allowed us to establish a procedure for the selection of producers of UV absorbing compounds from fungi, which could be applied in obtaining new natural organic filters for sunscreens.

Biometeorologinė informacija suteikia išankstinius perspėjimus apie sveikatai gresiantį pavojų, kaip meteorologinių sąlygų kompleksas veiks žmonių sveikatos būklę ar komfortiškumą. Šio darbo tikslas - nustatyti orų poveikį Lietuvos gyventojų sveikatai ir atlikti biometeorologinių sąlygų šalies teritorijoje vertinimą. Darbe atliktas Lietuvos gyventojų jautrumo orams sociologinis vertinimas. Nustatytas orų sąlygų poveikis širdies-kraujagyslių ligų kartojimuisi Vilniuje ir išskirtos meteojautriausios ligos ir jų priklausomybė nuo esamų meteorologinių sąlygų. Analizuota biometeorologinį šalčio poveikį nusakančio Vėjo žvarbumo ir karščio poveikį – „Humidex“ indekso kaita Lietuvoje. Įvertintas karščio poveikis Vilniaus gyventojų mirtingumui ir nustatyti indikatoriai tinkantys teikti karščio perspėjimus Lietuvoje. Atlikta Kauno MS išmatuotų ultravioletinės spinduliuotės dydžių kalibraciją bei įvertintas modelio STAR tinkamumas ultravioletinės spinduliuotės intensyvumo Lietuvoje prognozei. Disertacinio darbo rezultatai gali būti naudojami biometeorologinėms prognozėms sudaryti. Remiantis šiuo darbu, galima tobulinti egzistuojančią išankstinių perspėjimų apie stichinius, katastrofinius ir kitus pavojingus hidrometeorologinius reiškinius sistemą. / Biometeorological information provides early warnings about health risks and possible effects of complex meteorological conditions on human health or comfortability. The aim of the present research is to determine the weather impact on human health in Lithuania and accomplish evaluation of biometeorological conditions in the country. In the research a sociological evaluation of weather sensitivity of Lithuanian population was carried out. There also was measured the impact of the weather conditions on cardiovascular disease recurrent in Vilnius and the most meteo sensitive diseases were identified as well as their dependence on the current weather conditions. The change of indices describing biometeorological cold (Wind Chill) and heat („Humidex“) effects was analysed. The impact of heat on mortality of Vilnius residents was evaluated and appropriate indicators were determined to provide heat warnings in Lithuania. There was performed a calibration of ultraviolet radiation values measured in Kaunas MS and assessed the appropriateness of STAR model for forecasting of UV radiation intensity in Lithuania. The results of dissertation can be used to make biometeorological forecasts. On the basis of this work, the system of existing early warnings about elemental, catastroffic and other hazardous weather events could be improved.