Os poliésteres alifáticos, como poli(caprolactona) (PCL) e poli(ácido lático) (PLA), são comumente usados em produtos biodegradáveis. Esses materiais são ecológicos e o uso de fibras vegetais com estes polímeros corrobora em uma alternativa de lidar com os resíduos da agroindústria e da indústria madeireira. O objetivo deste estudo foi de investigar as propriedades resultantes da degradação abiótica e biótica das bioblendas de PCL/PLA e seus biocompósitos com fibras vegetais. As fibras vegetais avaliadas foram a de babassu (Orbignya phalerata), de cana-de-açúcar (Saccharum spp) e farinha de madeira (Pinus Ellioti). A bioblenda de PCL/PLA foi utilizada como referência na proporção de 70/30, 50/50 e 30/70 (m/m) e para cada biocompósito foi utilizado 20% de fibra vegetal com duas granulometrias, de 35 e 45 mesh. As misturas foram processadas via extrusão e moldados por compressão térmica em formato de fitas. As amostras foram expostas a intemperismo natural por um período total de 120 dias e avaliadas as mudanças de suas propriedades mecânicas, físicas, químicas, morfológicas e térmicas a cada 30 dias. Evoluções das superfícies deterioradas das amostras foram observadas por MEV e demonstraram que foram ocasionadas pelas condições climáticas severas e confirmadas por FTIR através de uma diminuição considerável dos grupos ésteres. A incorporação de maior quantidade PLA ao PCL nas bioblendas aumentou o módulo de elasticidade e resistência à tração. Os biocompósitos reforçados com fibras vegetais com granulometria de 45 mesh destacaram-se em maior resistência à tração, e, após envelhecimento natural de 30 dias apresentaram menor decaimento assim como o módulo elástico. A estabilidade térmica dos biocompósitos com farinha de madeira de Pinus e fibras de cana-de-açúcar foi maior do que as de babaçu. O biocompósito reforçado com fibras de cana-de-açúcar destacou-se com maior desempenho mecânico indicando que houve uma melhor interação entre fibra e matriz polimérica. Resultados do monitoramento da degradação biótica avaliados em câmara respirométrica indicaram que o PCL apresentou menor velocidade de biodegradação em relação ao PLA. As bioblendas e biocompósitos com maior teor de PCL mostraram menor produção de CO2 ao longo do período avaliado. O biocompósito com menor teor de PCL e reforçado com fibra de cana-de-açúcar destacou-se com uma maior velocidade de biodegradação e pela maior produção de CO2. As propriedades resultantes da degradação abiótica e biótica destes materiais auxiliam no desenvolvimento de produtos de vida útil curta, bem como, na preservação do meio ambiente. / Aliphatic polyesters, such as poly(caprolactone) (PCL) and poly(lactic acid) (PLA) have been commonly used in biodegradable products. These materials are ecological and use of vegetal fibers in these composites also provides an alternative way to deal with agricultural residues. This study aims to evaluate the properties resulting from the abiotic and biotic degradation of PCL/PLA bioblends and their biocomposites. The vegetal fibers evaluated were babassu (Orbignya phalerata), sugarcane (Saccharum spp) and wood flour (Pinus Ellioti). PCL/PLA bioblends were used as reference with 70/30, 50/50 and 30/70 (w/w) ratio and each biocomposite had 20% of vegetal fiber content with 35 and 45 mesh granulometry was used. The bioblends were processed by extrusion and molded in tape format. The samples were exposed to natural weathering for 120 days and the changes in their mechanical, physical, chemical, morphological and thermal properties were evaluated every 30 days. Damaged surface evolution was performed by SEM and showed that they were caused by the severe climatic conditions and confirmed by FTIR through a considerable decrease of the ester groups. Addition of PLA to the PCL in the bioblends increased the modulus of elasticity and tensile strength. Reinforcements with vegetable fibers with 45 mesh granulometry increased tensile strength, and, after natural aging of 30 days, showed lower decrease as well as the modulus. Thermal stability of the biocomposites with wood flour and sugarcane fibers was higher than babassu. Biocomposites reinforced with sugarcane fibers highlighted in the higher mechanical performance indicating that there was a better interaction between fiber and polymer matrix. Results of the monitoring of biotic degradation indicated that PCL presented a lower rate of biodegradation in relation to PLA. Bioblends and biocomposites with higher PCL content showed lower CO2 generation over the period evaluated. Biocomposites with lower content of PCL and reinforced with sugarcane fiber stood out in the greater speed of biodegradation and the greater production of CO2. Properties resulting from the abiotic and biotic degradation prompted changes in its structures and to facilitate its degradation in times lower than conventional and aid in the development of short-lived products as well as in the preservation of the environment.

With current scientific technologies, a significant amount of genetic information can be obtained from biological evidence found at a crime scene. Not only is it possible to identify the donor of the evidence through routine DNA profiling techniques, but new RNA based methods are being developed to determine the tissue type as well as the physical characteristics of the donor. Despite the information that can be obtained, the ability to determine the age or time the biological material was deposited at the crime scene has eluded the forensic community thus far. Timing is critically important as it could help police determine when the crime was committed. In this body of work an investigation was conducted into whether the degradation rates of nucleic acid macromolecules could serve as molecular clocks for age estimations. An attempt was made to gain a better understanding of the degradation products produced from an internal urban environment and to develop an optimal assay accordingly. A number of different RNA based techniques for ageing both hair and blood samples were also examined. Degradation assays have been traditionally designed around amplicon size however, it was established that testing loci stability is an essential requirement in the optimisation process. The results presented in this thesis suggest the reliability of the data can be increased when the two competing target species are selected from the same loci, which minimised the effect of loci susceptibility to degradation. It was determined that blood stains aged up to 60 days in an internal urban environment were best distinguished (in terms of age estimations) by using targets that differed in size by 170 to 240 base pairs, with one of the targets being between 200 and 300 base pairs in length. Despite using a robust TH01 qPCR assay it was established that an internal “urban” environment was not as stable as predicted and that seasonal temperature variation had a large effect on degradation rates. Interpretation of the results was therefore limited suggesting these optimised target sizes may only be relevant to the winter months. Using a carefully designed hermetically sealed dry swab we were able to remove moisture and inhibit the growth of DNA consuming micro-organisms. It was determined that bacteria alone can cause a 2-fold increase in the degradation rate of a sample aged at room temperature. In terms of integrity, storing samples at room temperature in a moisture free environment was equivalent to storing standard samples (exposed to normal humidity levels) in refrigerated conditions. It was also determined that the effect of bacterial degradation can be halved by lowering the storage temperature from room temperature to 4°C. RNA was examined in an attempt to reduce the large variations that had inhibited previous DNA methodologies. IL-6 and TNF-α were initially selected due to their rapid post-extraction change in expression levels. However, their levels were highly variable, unpredictable and therefore not suitable for this type of analysis even on samples that had been aged for only ten days. It is thought that their dynamic roles in a number of haemopoietic processes could be responsible for the poor results. A new RNA methodology, as described by Nolan et al (2008) was used to analyse samples that had been aged over 80 days. Four targets, AMICA1, MNDA, CASP1 and GAPDH were chosen based on their cell lineage as it was hypothesised that inter-donor variation could be reduced by using targets confined to the granulocytic cell lineage. Using the novel 3’/5’ assay, AMICA1, MNDA and CASP1 all performed poorly and no correlation could be determined between the 3’/5’ ratio and sample age. GAPDH showed some encouraging results with a correlation of 0.912 (age to 3’/5’ ratio) although initial stability over the first 20 days and the inter-donor variation were still limiting factors. It was also thought that the various mRNA degradation processes, in particular the 5’/3’ exonuclease activity, contributed to the poor results generally. A large inter-donor variation was a common aspect to all the blood based methodologies trialled. This meant that none of the methods had any practical value. As a result, an alternative RNA method was used to determine if it was possible to age another forensically important type of biological evidence; hair. Using a Reverse Transcription Quantitative PCR (RT-qPCR) assay, we monitored the Relative Expression Ratio (RER) of two different RNA species (18S rRNA and B-actin mRNA) in hair samples that were aged naturally over a period of three months. Overall the results presented here suggest that the age of hair samples containing follicular tags can be approximated using a second order polynomial (Age = 3.31RER2 - 2.85RER – 0.54), although with limitations.

Le travail présenté dans se manuscrit s'inscrit dans le domaine de la chimie et physico-chimie des polysaccharides. Une étude des propriétés physico-chimiques du xyloglucane en fonction de différentes conditions est d'abords réalisée, elle montre la difficulté d'obtenir des solutions stables à l'échelle moléculaire ainsi que la possibilité d'obtenir des nanoparticules à base de xyloglucanes. Le suivi de l'hydrolyse enzymatique du xyloglucane en solution par la diffusion de la lumière a mis en évidence l'agrégation des produits obtenus en solution. L'imagerie par la microscopie à force atomique a révélé l'importance de la surface dans le phénomène de dégradation. Enfin des dérivés de xyloglucane ont été obtenus par oxydation par le système TEMPO/NaOCl/NaBr, et des essais de préparation de conjugués xyloglucane-cytarabine ont été effectués. / The work presented in this manuscript is in the field of chemistry and physical chemistry of polysaccharides. A study of the physicochemical properties of xyloglucan under different conditions is carried around and showing the difficulty to obtaining stable solutions at the molecular level. The study also evidenced the possibility of obtaining nanoparticles based on xyloglucan. Monitoring of the enzymatic hydrolysis of xyloglucan in solution by light scattering indicated the aggregation of the degradation products. Imaging by atomic force microscopy revealed the importance of the surface in the degradation phenomenon. Finally xyloglucan derivatives were obtained by oxidation system TEMPO / NaOCl / NaBr, and test on the coupling of xyloglucan and cytarabine conjugates were made.

Os poliésteres alifáticos, como poli(caprolactona) (PCL) e poli(ácido lático) (PLA), são comumente usados em produtos biodegradáveis. Esses materiais são ecológicos e o uso de fibras vegetais com estes polímeros corrobora em uma alternativa de lidar com os resíduos da agroindústria e da indústria madeireira. O objetivo deste estudo foi de investigar as propriedades resultantes da degradação abiótica e biótica das bioblendas de PCL/PLA e seus biocompósitos com fibras vegetais. As fibras vegetais avaliadas foram a de babassu (Orbignya phalerata), de cana-de-açúcar (Saccharum spp) e farinha de madeira (Pinus Ellioti). A bioblenda de PCL/PLA foi utilizada como referência na proporção de 70/30, 50/50 e 30/70 (m/m) e para cada biocompósito foi utilizado 20% de fibra vegetal com duas granulometrias, de 35 e 45 mesh. As misturas foram processadas via extrusão e moldados por compressão térmica em formato de fitas. As amostras foram expostas a intemperismo natural por um período total de 120 dias e avaliadas as mudanças de suas propriedades mecânicas, físicas, químicas, morfológicas e térmicas a cada 30 dias. Evoluções das superfícies deterioradas das amostras foram observadas por MEV e demonstraram que foram ocasionadas pelas condições climáticas severas e confirmadas por FTIR através de uma diminuição considerável dos grupos ésteres. A incorporação de maior quantidade PLA ao PCL nas bioblendas aumentou o módulo de elasticidade e resistência à tração. Os biocompósitos reforçados com fibras vegetais com granulometria de 45 mesh destacaram-se em maior resistência à tração, e, após envelhecimento natural de 30 dias apresentaram menor decaimento assim como o módulo elástico. A estabilidade térmica dos biocompósitos com farinha de madeira de Pinus e fibras de cana-de-açúcar foi maior do que as de babaçu. O biocompósito reforçado com fibras de cana-de-açúcar destacou-se com maior desempenho mecânico indicando que houve uma melhor interação entre fibra e matriz polimérica. Resultados do monitoramento da degradação biótica avaliados em câmara respirométrica indicaram que o PCL apresentou menor velocidade de biodegradação em relação ao PLA. As bioblendas e biocompósitos com maior teor de PCL mostraram menor produção de CO2 ao longo do período avaliado. O biocompósito com menor teor de PCL e reforçado com fibra de cana-de-açúcar destacou-se com uma maior velocidade de biodegradação e pela maior produção de CO2. As propriedades resultantes da degradação abiótica e biótica destes materiais auxiliam no desenvolvimento de produtos de vida útil curta, bem como, na preservação do meio ambiente. / Aliphatic polyesters, such as poly(caprolactone) (PCL) and poly(lactic acid) (PLA) have been commonly used in biodegradable products. These materials are ecological and use of vegetal fibers in these composites also provides an alternative way to deal with agricultural residues. This study aims to evaluate the properties resulting from the abiotic and biotic degradation of PCL/PLA bioblends and their biocomposites. The vegetal fibers evaluated were babassu (Orbignya phalerata), sugarcane (Saccharum spp) and wood flour (Pinus Ellioti). PCL/PLA bioblends were used as reference with 70/30, 50/50 and 30/70 (w/w) ratio and each biocomposite had 20% of vegetal fiber content with 35 and 45 mesh granulometry was used. The bioblends were processed by extrusion and molded in tape format. The samples were exposed to natural weathering for 120 days and the changes in their mechanical, physical, chemical, morphological and thermal properties were evaluated every 30 days. Damaged surface evolution was performed by SEM and showed that they were caused by the severe climatic conditions and confirmed by FTIR through a considerable decrease of the ester groups. Addition of PLA to the PCL in the bioblends increased the modulus of elasticity and tensile strength. Reinforcements with vegetable fibers with 45 mesh granulometry increased tensile strength, and, after natural aging of 30 days, showed lower decrease as well as the modulus. Thermal stability of the biocomposites with wood flour and sugarcane fibers was higher than babassu. Biocomposites reinforced with sugarcane fibers highlighted in the higher mechanical performance indicating that there was a better interaction between fiber and polymer matrix. Results of the monitoring of biotic degradation indicated that PCL presented a lower rate of biodegradation in relation to PLA. Bioblends and biocomposites with higher PCL content showed lower CO2 generation over the period evaluated. Biocomposites with lower content of PCL and reinforced with sugarcane fiber stood out in the greater speed of biodegradation and the greater production of CO2. Properties resulting from the abiotic and biotic degradation prompted changes in its structures and to facilitate its degradation in times lower than conventional and aid in the development of short-lived products as well as in the preservation of the environment.

La décomposition des résidus végétaux joue un rôle essentiel dans le cycle biogéochimique des éléments nutritifs et influence le fonctionnement des écosystèmes. La composition biochimique intrinsèque des résidus végétaux est un facteur clé qui influe sur les processus de décomposition dans le sol tandis que la majorité des réactions biochimiques dans le sol, liées à la biodégradation des résidus végétaux, sont catalysées par des enzymes extracellulaires produites par les microorganismes. L'objectif global de cette étude était d'acquérir des connaissances fondamentales concernant l'impact de la qualité des résidus sur les fonctions microbiennes du sol et les modes d'intervention des enzymes du sol interviennent dans la décomposition des résidus végétaux. Cet objectif a été atteint en trois parties visant à : 1) déterminer le rôle des communautés initiales des résidus i.e. les microorganismes et leurs enzymes provenant des compartiments épiphytes et endophytes, et l'effet de la qualité des résidus végétaux sur les cinétiques des enzymes extracellulaires au cours du processus de décomposition dans le sol 2) étudier l'effet des fonctions microbiennes du sol (biomasse microbienne et enzymes extracellulaires) liées à la minéralisation sur la décomposition ultérieure de résidus introduits dans le même sol 3) explorer les interactions entre la disponibilité en azote et la décomposition des composés phénoliques par l'action des activités oxydo-réductases, et développer une méthode pour mesurer ces activités dans des sols contrastés en utilisant un seul substrat. L'approche générale de cette étude a été de sélectionner les résidus végétaux de qualité chimique variable pour obtenir des cinétiques contrastées de minéralisation du C. Le maïs (Zea mays L.) a été choisi comme plante modèle en raison de variations chimiques et structurales (Mexxal, F2, F2bm1, F292bm3) des parties aériennes (feuilles, entre-nœuds) et souterraines (racines). Des tiges de lin marqué au 13C ont été utilisées pour quantifier avec précision la minéralisation du carbone dans les différents réservoirs de carbone. Afin d'évaluer les relations entre la qualité des résidus végétaux et les fonctions biologiques associées au sol, des expériences en microcosmes contrôlés ont été réalisées en utilisant des sols agricoles et forestiers. La minéralisation du carbone, les caractéristiques chimiques des résidus (teneurs en C et N, les sucres totaux et lignine), la biomasse microbienne et les activités enzymatiques (L-leucine aminopeptidase (LAP), cellobiohydrolase (CBH-1), xylanase, cellulase et la laccase) ont été déterminées à différents stades de décomposition. Les résultats de la première étude ont indiqué que les activités de micro-organismes épiphytes et endogènes étaient du même ordre de grandeur dans le cas des racines, tandis que les activités des enzymes spécifiques (cellulase, xylanase et laccase) étaient fortement corrélées à la dégradation de leurs substrats cibles (glucanes, xylanes et lignine, respectivement). Dans la seconde étude, l'addition répétée de résidus a eu peu d'effet sur la biomasse microbienne et la dynamique enzymatique, sauf la LAP et la laccase. Ces résultats suggèrent que la qualité des résidus végétaux est le principal facteur déterminant les modes d'action de la biomasse microbienne et de leurs enzymes extracellulaires durant le processus de décomposition dans le sol. Les résultats de la dernière étude ont démontré que l'addition d'azote réprimait la minéralisation du carbone des résidus les moins lignifiés (F2, F2bm1), mais n'a pas affecté celle du résidu plus lignifié (F292bm3) au cours de la décomposition à long terme. L'ABTS est apparu comme un meilleur substrat que le L-DOPA, le pyrogallol et le TMB pour estimer les activités phénoloxydase et peroxydase.Mots clés: décomposition, biomasse microbienne, enzymes extracellulaires, qualité des résidus, maïs. / Plant residue decomposition plays a pivotal role in the biogeochemical cycling of nutrients and influences ecosystem functioning. The intrinsic biochemical composition of plant residues is a key factor influencing decomposition processes in soil while the majority of biochemical reactions in soil, related to the biodegradation of plant residues, are catalyzed by extracellular enzymes produced by microorganisms. The overall goal of this research study was to gain fundamental knowledge regarding the impact of residue quality on soil microbial functions and the principles by which soil enzymes mediate plant residue decomposition. This goal was achieved in three parts: 1) to determine the role of the initial residue community i.e. microorganisms and enzymes from the epiphytic and endophytic compartments and effect of plant residue quality on the extracellular enzyme kinetics during the decomposition process in soil 2) to investigate the effect of soil microbial functions (microbial biomass and extracellular enzymes) on the subsequent residue decomposition in the same soil 3) to explore the interactions between nitrogen availability and the decomposition of phenolic compounds through the action of oxydo-reductase enzymes activities and to develop a method to measure these activities in contrasted soils using a single substrate. The general approach of this study was to select plant residues with variations in their chemical quality to obtain contrasted C mineralization kinetics. Maize (Zea mays L.) was selected as a model plant because of variations in chemical and structural characteristics (Mexxal, F2, F2bm1, F292bm3) of aerial (leaves, internodes) and underground parts (roots). 13C-labeled flax stems were used to quantify accurately carbon mineralization in different carbon pools. To assess the relationships between plant residue quality and associated soil biological functions, controlled microcosm experiments were performed using agricultural and forest soils. Carbon mineralization and chemical characteristics (C and N contents, total sugars and lignin contents) of the plant residue, microbial biomass and enzyme activities (L-leucine aminopeptidase (LAP), cellobiohydrolase (CBH-1), xylanase, cellulase and laccase) were determined at different stages of decomposition. The results of first study indicated that activities of epiphytic and endogenic microorganisms were of the same order of magnitude in case of roots while the activities of specific enzymes (cellulase, xylanase and laccase) were highly correlated to the degradation of their target substrates (glucans, xylans and lignin, respectively). In the second study, little effect of repeated residue addition was observed on microbial biomass and enzyme dynamics except LAP and laccase. These results suggest that plant residue quality is the main factor which determines the fate/patterns of microbial biomass and their extracellular enzymes during decomposition process in soil. The results of last study demonstrated that nitrogen addition repressed the carbon mineralization of less lignified residues (F2, F2bm1) but did not affect more lignified residue (F292bm3) in long term decomposition. For estimation of phenol oxidase and peroxidase activities, ABTS appeared as a better substrate than L-DOPA, pyrogallol and TMB.Key words: decomposition, microbial biomass, extracellular enzymes, residue quality, maize.

Dissolved organic matter (DOM) is one of the largest carbon reservoirs on this planet and is present in aquatic environments as a highly complex mixture of organic compounds. The Florida coastal Everglades (FCE) is one of the largest wetlands in the world. DOM in this system is an important biogeochemical component as most of the nitrogen (N) and phosphorous (P) are in organic forms. Achieving a better understanding of DOM dynamics in large coastal wetlands is critical, and a particularly important issue in the context of Everglades restoration. In this work, the environmental dynamics of surface water DOM on spatial and temporal scales was investigated. In addition, photo- and bio-reactivity of this DOM was determined, surface-to-groundwater exchange of DOM was investigated, and the size distribution of freshwater DOM in Everglades was assessed. The data show that DOM dynamics in this ecosystem are controlled by both hydrological and ecological drivers and are clearly different on spatial scales and variable seasonally. The DOM reactivity data, modeled with a multi-pool first order degradation kinetics model, found that fluorescent DOM in FCE is generally photo-reactive and bio-refractory. Yet the sequential degradation proved a “priming effect” of sunlight on the bacterial uptake and reworking of this subtropical wetland DOM. Interestingly, specific PARAFAC components were found to have different photo- and bio-degradation rates, suggesting a highly heterogeneous nature of fluorophores associated with the DOM. Surface-to-groundwater exchange of DOM was observed in different regions of the system, and compositional differences were associated with source and photo-reactivity. Lastly, the high degree of heterogeneity of DOM associated fluorophores suggested based on the degradation studies was confirmed through the EEM-PARAFAC analysis of DOM along a molecular size continuum, suggesting that the fluorescence characteristics of DOM are highly controlled by different size fractions and as such can exhibit significant differences in reactivity.

Proton Exchange Membrane Fuel Cell (PEMFC) is the most commonly used type of hydrogen fuel cell and a promising solution for vehicular and stationary power applications. This research starts with an extensive review of the PEMFC research, including experimental testing, and performance modeling, and performance degradation modeling using relatively accurate and easy-to-use mechanistic models. Next, a new PEMFC performance degradation model is introduced by amending the semi-empirical, mechanistic performance model to support the design and control of PEMFC systems and fuel cell electric vehicles (FCEVs). The new model takes into account critical factors impacting PEMFC performance. The performance degradation due to the oxidation of catalyst platinum (Pt) and loss of active surface area is captured by fitting the degradation model parameters using experimental data to capture the observed PEMFC performance fading. The new performance degradation model is then tested and further improved under the four typical load modes that a PEMFC system experiences in a vehicular application under regular driving cycles. The model is also fitted with PEMFC experimental degradation data under different load modes to improve modeling accuracy. The new model is applied and tested using simulations of a representative FCEV. The actual power load on an 80 kW PEMFC system in the modeled FCEV was obtained using the Advanced Vehicle Simulator (ADVISOR) under the US EPA Urban Dynamometer Driving Schedule (UDDS). With the ability to predict the operation life of the PEMFC, the appropriate sizes of the PEMFC system and the energy storage system (ESS) can be determined. Improved power control and energy management can be developed to extend the operation life of the PEMFC and lower the lifecycle cost of the FCEV. / Graduate

Im 20. Jahrhundert haben sich Kunststoffe zu einem unverzichtbaren Material für eine moderne Gesellschaft entwickelt. Durch ihre vielfältigen Eigenschaften sind sie in jeden erdenklichen Einsatzbereich vorgedrungen und zu einem Teil der Menschheitsgeschichte geworden. Museen und andere Institutionen haben sich zur Aufgabe gemacht, diese Geschichte zu bewahren, zu erforschen und zu zeigen. Sie werden jedoch vor die Herausforderung gestellt, dass Kunststoffe in ihren Sammlungen im Vergleich mit Materialien wie Stein, Holz oder Metall deutlich schneller altern. Oft ist noch nicht viel über die Alterungsprozesse bekannt und es fehlt daher häufig an konkreten Handlungsanweisungen, um Objekte aus Kunststoff langfristig bewahren zu können. An dieser Stelle setzt die vorliegende Dissertation an. Diese befasst sich mit den Auswirkungen äußerer Einflüsse auf die Degradation eines der ersten und bekanntesten Kunststoffe und erarbeitet Empfehlungen zu dessen langfristiger Bewahrung. Gegenstand der Untersuchungen und Analysen ist der Kunststoff Celluloseacetat der Gläsernen Figuren des Deutschen Hygiene-Museums Dresden. Die Gläsernen Figuren sind dreidimensionale und lebensgroße Modelle des menschlichen und einiger tierischer Körper und haben sich im 20. Jahrhundert zu Ikonen ihrer Zeit entwickelt. Das transparente Celluloseacetat hat die Entwicklung dieser Objekte erst möglich gemacht und trägt maßgeblich zu deren Erscheinung und Erfolg bei. Celluloseacetat schrumpft jedoch mit zunehmendem Alter, wird brüchig, verfärbt sich und sondert Essigsäure ab. Darunter leiden das Erscheinungsbild sowie andere Materialien der Gläsernen Figuren. Durch intensive Begutachtungen sowie Messungen an diversen Gläsernen Figuren kann ein Einfluss der relativen Luftfeuchtigkeit auf die Degradation des Celluloseacetats bewiesen werden. Daher werden Modellversuche mit originalem Celluloseacetat durchgeführt und eine umfangreiche Analytik an diesem vorgenommen. Zur Analyse des Additivgehaltes wird eigens eine Ultraschallextraktionsmethode entwickelt. Die Ergebnisse zeigen einen sehr großen Einfluss der relativen Luftfeuchtigkeit auf das Celluloseacetat. Sowohl der Substitutionsgrad, Polymerisationsgrad als auch der Additivgehalt werden von einer höheren relativen Luftfeuchtigkeit negativ beeinflusst. Diese trägt des Weiteren zur Entstehung von Essigsäure bei. Der alleinige Einfluss der Essigsäure auf die Degradation des Celluloseacetats wird ebenfalls analysiert. Dieser ist geringer als angenommen und kommt vermutlich erst durch die Kombination mit der relativen Luftfeuchtigkeit zum Tragen. Aus den Ergebnissen werden Zusammenhänge sowie ein wahrscheinlicher Alterungsmechanismus abgeleitet. Ergänzt um eine theoretische Betrachtung, werden konkrete Empfehlungen zur langfristigen Erhaltung des Celluloseacetats und somit der Gläsernen Figuren ausgesprochen. Es wird eine Temperatur von 15 °C sowie eine relative Luftfeuchtigkeit von 30 % empfohlen. Dadurch können Additivmigration, Essigsäurefreisetzung und Depolymerisation signifikant reduziert und Auswirkungen auf andere Materialien vermieden werden. Die konkreten Empfehlungen werden dem Deutschen Hygiene-Museum Dresden als Teil eines Konzeptes zur präventiven Konservierung vorgeschlagen.:Inhaltsverzeichnis Kurzfassung Abstract Abkürzungsverzeichnis 1 Einleitung und Zielstellung 2 Theoretische Grundlagen 2.1 Polymere 2.1.1 Begriffe und Nomenklatur 2.1.2 Klassifizierung 2.1.3 Additive 2.1.4 Alterung 2.2 Celluloseacetat 2.2.1 Geschichte, Herstellung und Verwendung 2.2.2 Degradation und Konservierung 2.2.3 Künstliche Alterung 2.2.4 Analytik 2.3 Gläserne Figuren 2.3.1 Gläserner Mann 1935 2.3.2 Gläserne Frau 1935 2.3.3 Gläserner Mann 1962 2.3.4 Gläserne Kuh 1983 3 Materialien 3.1 Celluloseacetat und Celluloseacetatbutyrat 3.2 Chemikalien 4 Methoden 4.1 Charakterisierung von Celluloseacetat und Celluloseacetatbutyrat 4.2 Entwicklung einer Ultraschallextraktionsmethode für Additive 4.3 Bestimmung von Degradationsprodukten 4.3.1 Qualifizierung austretender Flüssigkeiten aus dem Celluloseacetat 4.3.1.1 Wassernachweis mit Cobaltchloridpapier 4.3.1.2 Bestimmung des pH-Wertes mit pH-Papier 4.3.1.3 Qualitative Bestimmung durch GCMS 4.3.2 Messung der Essigsäurekonzentration in der Luft 4.4 Künstliche Alterung von Celluloseacetat 4.4.1 Variation der relativen Luftfeuchtigkeit 4.4.2 Variation der Essigsäurekonzentration in der Luft 4.5 Charakterisierung von künstlich gealtertem Celluloseacetat 4.5.1 Bestimmung des Farbabstandes und des Helligkeitsunterschiedes 4.5.2 Bestimmung der Masse 4.5.3 Bestimmung des Additivgehaltes 4.5.3.1 Extraktion der Additive 4.5.3.2 Quantifizierung der Additive 4.5.3.3 GCMS Parameter 4.5.4 Bestimmung des Substitutionsgrades 4.5.4.1 Derivatisierung von Celluloseacetat 4.5.4.2 GCMS-Bestimmung des Substitutionsgrades 4.5.5 Bestimmung des Polymerisationsgrades 4.6 Analyse des Originalmaterials ausgewählter Gläserner Figuren 5 Ergebnisse und Diskussion 5.1 Charakterisierung von Celluloseacetat und Celluloseacetatbutyrat 5.2 Ultraschallextraktion von Additiven 5.3 Bestimmung von Degradationsprodukten 5.3.1 Beobachtungen 5.3.2 Austretende Flüssigkeit 5.3.3 Essigsäurekonzentration 5.4 Charakterisierung von künstlich gealtertem Celluloseacetat 5.4.1 Optische Veränderungen 5.4.2 Farbabstand und Helligkeitsunterschied 5.4.3 Masse 5.4.4 Additivgehalt 5.4.5 Substitutionsgrad 5.4.6 Polymerisationsgrad 5.5 Analyse des Originalmaterials ausgewählter Gläserner Figuren 5.6 Schlussfolgerungen zur Degradation und zum Alterungsmechanismus 5.7 Praktische Anwendung der erzielten Ergebnisse 6 Zusammenfassung und Ausblick Danksagungen Institutionen Publikationen Abbildungsverzeichnis Tabellenverzeichnis Literaturverzeichnis Eigenständigkeitserklärung

One of the most pressing problems nowadays is climate change and global warming. As it name indicates, it is a problem that concerns the whole earth. There is no doubt that the main cause for this to happen is human, and very related to non-renewable carbon-based energy resources. However, technology has evolved, and some alternatives have appeared in the energy conversion sector. Nevertheless, they are relatively young yet. Since the growth in renewable energies technologies wind power and PV are the ones that have taken the lead. Wind power is a relatively mature technology and even if it still has challenges to overcome the horizon is clear. However, in the PV case the technology is more recent. Even if it is true that PV modules have been used in space applications for more than 60 years, large scale production has not begun until last 10 years. This leaves the uncertainty of how will PV plants and modules age. The author will try to analyse the aging of a specific 63 kWp PV plant located in the roof of a building in Gävle, monitoring production and ambient condition data, to estimate the degradation and the new nominal power of the plant. It has been found out that the degradation of the system is not considerable. PV modules and solar inverters were studied, and even if there are more elements in the system, those are the principal ones. PV modules suffered a degradation of less than 5%, while solar inverters’ efficiency dropped from 95,4% to around 93%.

Thermal oil oxidation is an important reason for the engine oil degradation in trucks. Having a comprehensive model that includes all the influential factors while it is feasible for being implemented in the ECUs, was aimed for this work. Therefore, the chemical investigating of the problem leaded to propose a first kinetic model and its thermal analysis caused modelling the oil thermal behaviour. The latter was developed for four compartments: Bearings, turbocharger, piston cooling and oil sump in the oil path through the lubrication system, because the highest oil temperature happens due to friction, combustion of fuels and exhaust gas transportation. Independency from the design parameters of the compartments and simplicity of models for the ECU implementation caused to investigate two various modelling hybrid approach: physical modelling and control theory approach. The first one was done for the bearings and piston cooling, and showed a high level of complexity leading to switch to the second approach. The latter was applied for all compartments while it satisfied requested requirements. To adjust and evaluate the models, an experimental campaign was devoted to acquiring the needed parameters with consideration of the project budget. Also using the previous simulation and experimental efforts at the company provided a possibility to develop flow rate sub-models used in the thermal modelling. The proposed model for all compartments, well predicted the oil thermal behaviour for both stationary and dynamic operating conditions. A comparison between the experimental data for the oil in the oil sump and turbo charger was done to show the reliability of the related models in both stationary and transient statuses. For the bearings, the simulation data for stationary condition were applied as a reference. The modelled oil temperature after piston cooling was compared to a set of experimental data that presented the probable temperature in some conditions close to stationary operating points.