The subject of this theses is a preparation of chemical UV dosimeters working on diverse principles and their printing. Three UV dosimeters were prepared. The first one is based on a photocalalytic reaction of titanium dioxide with redox dyes. Two other dosimeters are based on a reaction of a photolabile substance able to produce an intermediate reacting with a dye. Prepared dosimeter compositions were coated using a material roll-to-roll printing machine on a corona-treated PET foil. Prepared dosimeter compositions were calibrated for desired exposition to UV radiation doses. Validity of a reciprocity law was verified.

Ce travail de thèse avait pour objectif d’étudier différents vieillissements des copolymères d’éthylène et de norbornène (ENC), utilisés comme conditionnement de produits pharmaceutiques. Grâce à la stratégie analytique adoptée qui a fait appel à différentes techniques de caractérisation, telles que les techniques séparatives comme la chromatographie d’exclusion stérique, la chromatographie liquide haute performance à polarité de phases inversée, les techniques spectrales dont la spectroscopie infra rouge à transformée de Fourier et la spectroscopie UV, les techniques d’analyse thermique à travers l’analyse thermogravimétrie et la calorimétrie différentielle à balayage, puis d’une étude de toxicité des produits de dégradations, nous avons pu mettre en évidence différents types de modifications dans le volume du matériau après vieillissement. La modification principale dans la masse du matériau, observée à la dose réglementaire de stérilisation (25 kGy), est la scission des chaînes du polymère qui s’accompagne de la création de composés de basses masses molaires, donc de migrants potentiels risquant d’influencer la sécurité d’emploi des ENC. Puis pour des doses élevées de rayonnement (150 kGy) et pendant 500h d’exposition UV, on a la réticulation des chaînes.La présence de l’additif (l’antioxydant phénolique l’Irganox 1010®) empêche la création des CBMM après vieillissements. Cependant, en absence d’additif, les vieillissements génèrent de nouveaux CBMM.Toutefois, l’étude de toxicité montre une certaine toxicité à 150 kGy du grade ENC / The aim of this thesis work was to study different ages of copolymers of ethylene and norbornene (ENC), used as packaging of pharmaceutical products. Thanks to the analytical strategy adopted using different characterization techniques, such as separation techniques such as size exclusion chromatography, reverse phase high performance liquid chromatography, spectral techniques including infrared spectroscopy transforming of Fourier and UV spectroscopy, thermal analysis techniques through thermogravimetric analysis and differential scanning calorimetry, and then a toxicity study of degradation products, we were able to highlight different types of modifications in the volume of the material after aging. The main modification in the bulk of the material, observed at the prescribed sterilization dose (25 kGy), is the cleavage of the polymer chains, which is accompanied by the creation of compounds with low molar masses, and therefore potential migrants, which are likely to influence ENC job security. Then for high doses of radiation (150 kGy) and for 500h UV exposure, there is the crosslinking of the chains. The presence of the additive (the phenolic antioxidant Irganox 1010®) prevents the creation of MBMM after aging. However, in the absence of an additive, aging generates new CBMMs. However, the toxicity study shows some toxicity at 150 kGy of the ENC.

Several applications require the detection of terrestrial UV-C signatures. Efficiency, compactness, environmentally friendly and cost-effective requirements for UV-C–detectors resulted in a research interest in wide-bandgap (WBG) semiconductor-based photovoltaic diodes with a 280 nm cut-off wavelength. Advances in producing group-III-nitride materials allowed the growth of high quality Al[x]Ga[1−x]N, a direct-WBG ternary semiconductor in which the Al mole fraction (x) could be varied, allowing for a tuneable bandgap that made the semiconductor intrinsically 'blind' to longer wavelengths and responsive to selected wavelengths shorter than 360 nm. This dissertation reports on the development and characterization of a tuneable AlGaN-based solar-blind UV-sensitive Schottky photodiode. A fabrication procedure was established using optimized metallization techniques derived from literature. This included metallization schemes, metal thicknesses and annealing methods for metallization of both the ohmic and Schottky contacts for a front-irradiated photodiode. Characterization was done with a newly constructed optoelectronic characterization system. Electrical characterization was performed inside a light-tight shielded enclosure and a software routine aided in applying current–voltage and capacitance–voltage measurements on a Schottky diode. Spectral characterization made use of either a UV source or a visible-to-near-infrared source that was coupled to a monochromator that allowed for wavelength selection. The monochromatic electromagnetic radiation was guided by an optical fibre from the monochromator into the enclosure where the photodiode was irradiated. An additional software routine was developed that allowed for the automation of the spectral characterization. The system was calibrated against standards traceable to the National Institute of Standards and Technology (NIST) by following the photodetector substitution method. The study concluded with the manufacturing of an epoxy wire-bonded front-irradiated four-quadrant detector that was mounted on a commercial microchip carrier. Metal depositions were done through physical contact masks. The quadrants were surrounded with optimized layered ohmic contacts and a quadrant consisted of a thin-film iridium(IV) oxide (IrO₂) as Schottky contact that is UV transmissive with a Au contact on top to which a wire was bonded. Optoelectronic characterization verified that the four-quadrant detector was intrinsically solar-blind and showed good uniformity across the quadrants. Electrical parameters obtained included an average ideality factor of 1.97 ± 0.09, a Schottky barrier height of (1.22 ± 0.08) eV, a reverse leakage current density of (2.1 ± 3.3) nA/cm² and a series resistance of (120 ± 30) Ω. Spectral parameters obtained included a (275 ± 5) nm cut-off wavelength, an average current responsivity at 250 nm of (28 ± 1.0) mA/W with a quantum efficiency of (14 ± 0.5) % and an UV-to-visible and near-infrared rejection ratio between 10³ and 10⁵ for 400 nm to 1100 nm wavelengths. These characteristics allowed for the detector to be used in demonstrating a working solar-blind UV-sensitive electro-optic device. / Dissertation (MSc)--University of Pretoria, 2015. / Physics / Unrestricted

miRNAs are short non-coding RNA molecules which play role in post-transcriptional regulation of gene expression. Thus, miRNAs are related to a variety of physiological processes and diseases, e.g. some tumours or viral infections. In this diploma thesis we studied temperature-induced dissociation of complexes that simulated pairing of miRNA with target mRNA. For these purposes we used UV absorption spectroscopy and Raman spectroscopy. Measured spectra were then treated by means of a factor analysis. The aim of the thesis was to determine thermodynamic parameters of the complexes dissociation and to clarify how inner loops and bulges affect the stability of oligonucleotide duplexes. Also, we have tested the suitability of the used approach for study of oligonucleotide complexes. We have shown that factor analysis of temperature dependent UV absorption spectra is a proper base to determine thermodynamic parameters of the duplex dissociation. Raman spectra were affected by large errors, nevertheless they enabled to observe some structural changes related to the transition. It has been shown that the bulge loop present in the studied complex reduces both its flexibility and the energetic preference of its formation.

Like many other animals, butterflies are able to visually perceive the ultraviolet (UV) light; many species even have patterns on their wings which are visible in this part of the electromagnetic spectrum. Over the last forty years, it has been shown that these UV patterns play an important role in behaviour of many butterflies, especially in relation to sexual selection - they are involved in the process of recognising a suitable mate, and likely can signal some of the mate's qualities, such as its age, ability to handle stressful environmental factors, or efficiency in foraging. The patterns may also be used for taxonomical purposes. This dissertation thesis contains a comprehensive research into ultraviolet patterns of the Gonepteryx brimstones, with a primary focus on the issue of environmental influences in relation to the expression of these traits, on the patterns' potential role in sexual selection, or on their evolution. It has been successfully demonstrated that UV patterns of at least some Gonepteryx species are affected by the environment to a strong degree, significantly more than the traits not involved in sexual selection. On the whole, the conclusions made by submitted publications suggest that UV patterns play a role in the sexual selection of the chosen brimstones, though it is not clear...

A bst r a ct Ultravi olet ( U V) mea ns' bey o n d vi olet' (fr o m t he Lati n - ultra - bey on d), w here by vi oletis t he c ol o ur wit h hig hestfre q ue nciesi n t he'visi ble'lig ht s pectr u m. By'visi ble' we refer t o h u ma n visi o n b utit m ust be ta ke n i nt o acc o u nt t hat h u ma n vis ual perce pti o n is i n c o m paris o n t o ma ny ot her orga nis ms rat her li mite di n ter ms of wavele ngt hsit ca n perceive. isis w hy c o m m u nicati o ni n t he U V s pectr u mis of- te n calle d hi d de n, alt h o ug hit m ostli kely plays a ver yi m p orta nt r olei n t he c o m m u nicati o n of vari o us ki n ds ofi nf or mati o n a m o ng a wi de variet y of orga nis ms. e ai m of t he prese nt t hesis is t o el uci date t he fu ncti o ns a n d relative i m p orta nce of U V pa er ns mai nl y i n L e pi d o ptera fr o m a h olistic ec ol o gical a n d ev ol uti o nar y pers pective. U V re fl ecta nce ca n- n ot be st u die d i n is olati o n: i m p orta nt i nteracti o ns a m o n g several ot her varia bles s uc h as li g ht c o n - dit i o ns, ge neral o ptic pr o perties of nat ural o bjects, t he vis ual s yste m, a n d si g nal pr ocessi n g are t h us disc usse d as well, b ut a n overall e m p hasis o n U V re flecta nce is mai ntai ne d t hr o u g h o ut. M ore over, t his w or k...

L’entreprise Chomarat produit des feuilles en polyoléfine pour les revêtements intérieurs de voitures. Ces feuilles sont grainées afin de leur donner un aspect de surface particulier qui constitue un élément psychosensoriel important pour le consommateur. Les feuilles grainées doivent être thermoformées afin de pouvoir leur imprimer la forme de la structure rigide qui les supportera. L’étape de thermoformage se déroule à haute température et constitue de ce fait une étape critique du processus. En effet, lors de la déformation en température, l’étirement du matériau tend à déformer le grain de façon non homogène, voire à le faire disparaître. Pour obtenir des matériaux avec une bonne tenue du grain, les feuilles grainées sont partiellement réticulées. Ce travail de thèse vise à développer des formulations réticulables répondant à cette problématique. Deux voies de réticulation ont été envisagées : la réticulation par irradiation sous faisceau d’électrons et ou par insolation UV. Cette dernière méthode de réticulation est totalement novatrice dans ce domaine industriel. Les terpolymères éthylène-propylène-diène monomère (EPDM) présentent des caractéristiques favorisant la réticulation. L’effet de l’irradiation (EB ou UV) sur ces élastomères, ainsi que leurs mélanges avec du polypropylène (PP), a été étudiée. Les caractérisations ont principalement été menées par des mesures de rhéologie, des mesures de taux de gel et des calculs de densité de réticulation. Dans un premier temps, seule l’irradiation EB a été testée, sur des EPDM ainsi que sur d’autres types d’élastomères. Ensuite, les effets de l’irradiation UV ont été étudiés à travers la mise en place d’une étude modèle sur des oligomères de faibles masses choisis pour simuler le comportement des doubles liaisons des EPDM. La composition des différentes formulations étudiées comprenait donc un oligomère, un monomère multifonctionnel et un photoamorceur permettant la photoréticulation. Suite à cette étude, les meilleurs couples « photoamorceur / agent de réticulation » ont été transposés à des EPDM, d’abord en utilisant un EPDM de faible masse molaire puis un EPDM de haute masse molaire utilisé couramment dans les formulations au niveau industriel. Enfin, l’ajout du PP et en dernier lieu l’ajout de pigments et d’agents anti-UV ont été étudiés sur l’efficacité de la photoréticulation. / The Chomarat company manufactures polyolefin based sheets for automotive parts. These sheets are grained in order to give them a particular surface pattern which represents an important psycho-sensory aspect for consumers. The grained sheets must be thermoformed to give them the shape of the rigid structure on which they will be set in place. The thermoforming step is proceeded at high temperature and is therefore a critical step of this process. Indeed, while being deformed in temperature, the stretching of the material tends to distort the grained pattern in a non-homogeneous way and even to cancel it. In order to obtain materials that give an acceptable retention of the pattern after being thermoformed, the grained sheet must be partially crosslinked. This thesis work aims to develop crosslinkable formulations that are able to achieve this challenge. Two crosslinking methods have been considered: crosslinking using electron beam (EB) irradiation or UV irradiation. This last method is a pioneering crosslinking pathway in this industrial field. Terpolymers of ethylene-propylene-diene monomers (EPDM) have chemical structures that promote crosslinking. The effect of irradiation (EB or UV) on these elastomers, as well as on their blends with polypropylene (PP) have been studied. The characterisations have been mainly monitored using rheological measurements, gel contents measurements and crosslinking densities calculations. Firstly, only the effects of EB irradiation on EPDM and other types of elastomers have been investigated. Then, the effects of UV irradiation have been studied through a modelling study on low mass oligomers chosen to mimic the behaviour of EPDM double bonds. The different formulations studied were composed of an oligomer, a multifunctional monomer acting as a crosslinker and a photoinitiator allowing the crosslinking. Following this study, the best photoinitiator/crosslinking agent couples were transposed to EPDM, using firstly a low mass EPDM then a high mass one frequently used in formulations in industrial fields. At last, the effects on the photocrosslinking efficiency of adding first PP then pigments and anti-UV agents have been examined.

This work presents the development of a new pretreatment for clear coated wood, that aims to increase the photoprotection of exterior wood products, and at the same time make the system more environmentally friendly. The pretreatment comprises the reactive UV absorber 2-hydroxy-4(2,3-epoxy­propoxy)-benzophenone (HEPBP), which has a primary epoxy group that can be covalently attached to the hydroxyl groups of the wood substrate. This reactant is accompanied by renewable epoxy functionalized soybean oil (ESBO), which contains a secondary epoxy group that also has the ability to react with the substrate and that promotes the compatibility between the two reactants. The ESBO further seems to have the advantage of increasing the flexibility of the pretreated veneers as well as decreasing the amount of water in the cell wall of the wood. The study was performed in two parts where the first part focused solely on the development and performance of the pretreatment, whereas the second part used the knowledge gained from part one to evaluate the pretreatment in combination with an acrylic clear coating. Grafting reactions were performed on thin wood veneers heated in solvent. In the first part the reaction parameters, temperature and reaction time, were varied to study their effects on the final properties of the pretreatments. The veneers where then analyzed using FTIR to determine if grafting was achieved. Results show that grafting was successful for reactions performed at temperatures above 90 °C. For part two, grafting was successful for both the boil- and dip process, indicating that a considerably shorter reaction time can be used. Samples from both part one and two where then exposed to accelerated ageing and the color change was measured to estimate the UV-resistance. The first part showed improved UV-resistance for some of the pretreatments, whereas the second part was more difficult to evaluate due to the top coat, but a slight improvement can be seen for samples using the pretreatment. A positive result for part two is also that the pretreatment do not appear to affect the adhesion between the substrate and the top coat. It is hence concluded that the proposed pretreatment is a possible way of increasing the photostability of exterior wood. / Detta arbete beskriver utvecklandet av en ny förbehandling för klarlackat trä som syftar till att öka UV-beständigheten av träprodukter för utomhusbruk. Arbetet syftar även till att utveckla systemet till att bli miljövänligare än nuvarande liknande produkter på marknaden. Förbehandlingen utnyttjar primära epoxidgrupper hos den reaktiva UV-absorbenten 2-hydroxy-4(2,3-epoxy­propoxy)-bensofenon (HEPBP) för att skapa kovalenta bindningar till hydroxylgrupper hos träet. Den andra komponenten i systemet är förnyelsebar epoxiderad sojaolja (ESBO) innehållande sekundära epoxidgrupper som även dessa kan binda kovalent till träytan, samt gynna kompatibiliteten mellan de två reaktanterna. Oljan verkar dessutom öka flexibiliteten av förbehandlingen, samtidigt som den minskar mängden vatten som tränger in i cellväggen. Studien utfördes i två delar där den första delen fokuserade enbart på att utveckla förbehandlingen, medan den andra delen utnyttjade information från den första delen för att utvärdera funktionen av förbehandlingen i kombination med en akrylatbaserad klarlack. Ympningsreaktionerna utfördes på tunna träfaner i uppvärmd lösning. I första delen studerades hur temperatur- och reaktionstidsförändringar påverkar den slutgiltiga prestationen av förbehandlingen, och FTIR användes då för att verifiera ympningen. Resultaten visar att ympningen var lyckad för reaktioner utförda vid reaktionstemperaturer över 90 °C. För del två ansågs ympningen lyckad för både dopp- och kokreaktionen, vilket tyder på att betydligt kortare reaktionstider skulle kunna användas. Prover från både del ett och två utsattes sedan för accelererad åldring där färgförändringen av proverna mättes för att uppskatta UV-resistensen av behandlingarna. Första delen visade på ökad UV-beständighet för vissa av behandlingarna. Del två var dock svårare att utvärdera till följd av klarlacken, men en liten förbättring kan noteras för prover som är förbehandlade. En positiv notering från del två är även att adhesionen mellan klarlacken och träytan inte verkar ha påverkats av förbehandlingen. Med detta som grund dras slutsatsen att den föreslagna förbehandlingen kan förbättra UV-resistensen av klarlackat trä för utomhusbruk. / QC 20120330

<p>Predmet istraživanja ove disertacije je monitoring i analiza ultraljubičastog zračenja, toplotnih indeksa i zagađujućih materija u vazduhu većih naselja na teritoriji Vojvodine. Cilj istraživanja je da se prostornom i vremenskom analizom posmatranih parametara dođe do &scaron;to optimalnijih saznanja o stanju kvaliteta životne sredine na području Vojvodine kao i stvaranje jedinstvene baze podataka koja će služiti za buduća istraživanja. U radu je ispitan odnos između sunčevog globalnog i UV zračenja, izvedena i verifikovana empirijska jednačina za procenu dnevnih suma UV-B zračenja u osam naselja za period 1981-2008, analizirane koncentracije pet zagađujućih materija u sedam naselja za period 2001-2008. godina i analizirani toplotni indeksi u sedam naselja u periodu od 1992. do 2008. Analiza pokazuje da rekonstruisane vrednosti dnevnih suma UV-B zračenja i srednji godi&scaron;nji toplotni indeksi u svim naseljima pokazuju tendenciju rasta i da dominantan uticaj na kvalitet vazduha u naseljima Vojvodine imaju čestice. Napravljena je jedinstvena baze podataka sa vrednostima koncentracija zagađivača vazduha, toplotnih indeksa, UV i globalnog zračenja.</p> / <p>This study analyzes UV radiation, heat indexes and air pollution in town in Vojvodina region. Objective of the thesis is to provide scientific facts about environmental quality in Vojvodina, as well as, to generate unique data base for the future research. The relationship between UV-B and global radiation has been studied and correlation equation for estimating UV-B from global radiation has been deduced. Equation was used for UV-B radiation calculation in eight towns in Vojvodina region during the period 1981-2008. This study also analyzes concentrations of five air pollutant in during the period 2001-2008, and heat index during the period 1992-2008. in seven towns in Vojvodina. The results from this study show growth UV-B radiation and heat index in all towns, and denote particulate maters as main air pollutants in Vojvodina towns.</p>

The behaviour of humic acids in aqueous solutions is closely connected to the content of acid functional groups and their dissociation abilities. The titration methods are the most often used for the research of acid-base characteristics of humic acids, their results should lead to the determination of the content of functional groups and their pKa. However the determined values depend on many factors including the titration speed. The spectrophotometric determination of dissociation constant was used in this diploma thesis. Reliability of this method was confirmed in bachelor thesis where is mentioned that spectrophotometric determination of pKa corresponds with realistic dissociation behaviour of humic acids in the water much more better than values obtained from titration methods. The principle of newly used spectrophotometry method is the preparation of humic acids solutions in three different media with different pH values. Acid groups of humic acids are practically completely dissociated in intensely basic environment and the measured absorbance is caused by anion of „humate“. On the contrary their dissociation in acid environment is suppressed so much that we measure the absorbance of non-dissociated molecules of humic acids. Deionized water was used like neutral solvent. Water was replaced by acetic buffer in this thesis because of water’s properties which have significant influence on solutions' pH. Buffer was used for diluting or for solubilisation and in these both cases more stable pH values were occurred. The aim of this diploma thesis is investigate UV/VIS spectra of various solutions of humic acids with different values of pH and determinate mean value of pKa of humic acids which could be used like comparison of dissociation behaviours for vary samples. Values of acid dissociation constant were determined from measured dates and compared with values obtained by titration method. The UV/VIS spectra gained in combination with the results of pH measuring and the conductivity next showed the differences in the behaviour of differently prepared samples of humic acids.