Submitted by Renata Lopes (renatasil82@gmail.com) on 2017-01-12T12:51:08Z No. of bitstreams: 1 laragouveaalmeidamartinsatalla.pdf: 1481439 bytes, checksum: 5170ffd61eff8e2caba1d16c0795e644 (MD5) / Approved for entry into archive by Diamantino Mayra (mayra.diamantino@ufjf.edu.br) on 2017-01-31T11:16:46Z (GMT) No. of bitstreams: 1 laragouveaalmeidamartinsatalla.pdf: 1481439 bytes, checksum: 5170ffd61eff8e2caba1d16c0795e644 (MD5) / Made available in DSpace on 2017-01-31T11:16:46Z (GMT). No. of bitstreams: 1 laragouveaalmeidamartinsatalla.pdf: 1481439 bytes, checksum: 5170ffd61eff8e2caba1d16c0795e644 (MD5) Previous issue date: 2009-12-10 / O presente estudo teve como objetivo avaliar a influência do tratamento da dentina radicular com clorexidina a 2% e ácido cítrico a 10% na resistência de união de pinos de fibra de vidro cimentados com cimento resinoso RelyX Ultimate (3M ESPE) associado a um adesivo autocondicionante Single Bond Universal (3M ESPE). Quarenta e cinco dentes humanos unirradiculares foram selecionados e seccionados na junção cemento-esmalte, padronizando-os com 14 mm de comprimento. Após tratamento endodôntico, as raízes foram divididas aleatoriamente em 3 grupos (n=15) de acordo com o tratamento prévio do conduto radicular: G1, nenhum tratamento; G2, aplicação de gel de clorexidina a 2% (Rioquímica®) por 60 segundos; G3, aplicação de ácido cítrico a 10% (Idem per Idem Farmácia de Manipulação Ltda) por 60 segundos. Posteriormente, foi aplicado o adesivo nos condutos e nos pinos de fibra de vidro (White Post, FGM) e estes foram cimentados com cimento resinoso (RelyX Ultimate - 3M ESPE), sendo fotopolimerizados por 40 segundos. As raízes foram seccionadas axialmente em discos de 2 mm e os espécimes foram submetidos ao teste de push-out. As médias dos valores obtidos (MPa) foram analisadas por meio dos testes one-way ANOVA e Tukey (α=0,05) e os tipos de falhas analisadas em estereomicroscópio com aumento de 8,0X. Os resultados mostraram que não houve diferença estatisticamente significativa entres os grupos avaliados, assim como quando comparados os terços radiculares em cada grupo (p>0,05), entretanto resultados significantes foram encontrados entre os grupos G1 e G2 na região cervical (p=0,045). Falhas mista e adesiva entre cimento e dentina foram mais prevalentes. Pôde-se concluir que o uso da clorexidina a 2% no conduto radicular pode interferir na resistência de união de pinos de fibra de vidro e que o ácido cítrico não influenciou nos resultados. / The aim of this study was to investigate the influence of root dentine treatment with 2% chlorhexidine and 10% citric acid on bond strength of fiberglass post cemented with self-etching cement. Forty five human single-rooted teeth were selected and sectioned in the cement-enamel junction, standardizing them with 14 mm length. After endodontic treatment the roots were randomly divided in 3 groups (n=15) according to the previous treatment of the root canal: G1, no treatment; G2, application of 2% chlorhexidine (Rioquímica®) for 60s; G3, application of 10% citric acid (Idem per Idem - Farmácia de Manipulação Ltda) for 60s. Subsequently, the self-etching adhesive Single Bond Universal (3M ESPE) was applied in the canals and on the fiberglass post (White Post, FGM) and these ones were cemented with resin cement (RelyX Ultimate - 3M ESPE), and light polymerized for 40s. The roots were sectioned transversely in slides of 2 mm thickness and the push-out test was performed. Data were analyzed by one-way ANOVA and Tukey test (α=0.05) and the types of failures were analyzed under stereomicroscopy (8.0X). The results show that there was no statistically significant difference between the groups, as well as when comparising bond strength in root thirds in each group (p>0.05), however, significant results were found between groups G1 and G2 in the cervical third (p=0.045). Mixed and adhesive failures between cement and dentine were predominant. It can be concluded that the use of 2% chlorhexidine in the root canal can interfere in the fiberglass posts bond strength.

Resultados de pesquisas prévias tem encontrado potencial aumentado para a consolidação de enxertos ósseos mediante desmineralização do material enxertado e/ou das superfícies de consolidação. Entretanto há carência de embasamento apoiado em evidências biológicas do benefício de tal procedimento. Para testar esta hipótese, o tecido ósseo da calvária de cobaias (Cavia porcellus) foi exposto ao condicionamento por ácido cítrico durante 15, 30, 90 e 180 segundos (grupos teste). Quarenta e cinco discos ósseos de três milímetros de diâmetro foram removidos dos animais, dos quais 36 foram condicionados com ácido cítrico pH 1 a 50% e nove não receberam condicionamento (grupo controle). Sobre nove discos de cada grupo foram cultivados pré-osteoblastos MC3T3-E1 durante 24, 48 e 72 horas (três discos de cada grupo em cada tempo). Análises da morfologia celular, do número de células aderidas sobre as superfícies e da área de cobertura destas superfícies por préosteoblastos foram realizadas à microscopia eletrônica de varredura. Observou-se aumento do número de células aderidas às superfícies com o tempo, independentemente de haver condicionamento ou de seu tempo de aplicação. Entretanto, essa diferença só foi estatisticamente significante intragrupos (p<0,05) e quando comparados os períodos de 24 e 72 horas de incubação. A área de cobertura das superfícies por células aumentou significantemente com o tempo somente nos grupos teste, também entre os períodos de incubação de 24 e 72 horas (p<0,01). O grupo controle apresentou-se com 50% ou menos de área de cobertura superficial em relação aos demais. A duração de aplicação do ácido não interferiu significantemente nesse parâmetro de avaliação, mas nos grupos 15 e 30, a área de recobrimento ósseo mais do que triplicou às 72 horas em relação às 24 horas (p<0,01), com cerca de 70% das superfícies cobertas por células, contra 30% no grupo controle. Conclui-se que a desmineralização óssea nos tempos de condicionamento estudados propicia um substrato sobre o qual as células pré-osteoblásticas adquirem morfologia compatível com estágio de diferenciação mais avançado, promovendo maior cobertura de área, o que aumenta o potencial para deposição de novo osso sobre essas superfícies em comparação ao tecido não condicionado. / Results of previous research has found increased potential for the consolidation of bone grafts by demineralization of the graft material and / or areas of consolidation. However there is a lack of foundation supported by biological evidence of benefits from such procedures. To test this hypothesis, the bone tissue of the calvaria of guinea pigs (Cavia porcellus) were exposed to conditioning by citric acid for 15, 30, 90 and 180 seconds (test group). Forty-five bone disks measuring three millimeters in diameter were removed from the animals, of which 36 were conditioned with citric acid pH 1 to 50% and nine did not receive conditioning (control group). About nine disks in each group were pre-cultured with MC3T3- E1 osteoblasts for 24, 48 and 72 hours (three discs of each group at each time point). Analysis of cell morphology, number of cells attached on the surface and the coverage area of these surfaces by pre-osteoblasts were performed on scanning electron microscopy. There was na increase in the number of cells attached to surfaces over time, regardless of conditioning or application time. However, this difference was not statistically significant intra-group (p <0.05) when comparing the periods of 24 and 72 hours of incubation. The coverage area of the surfaces of cells increased significantly with time only in the test groups, also among the incubation periods of 24 and 72 hours (p <0.01). The control group presented with 50% or less of surface area coverage compared to the other. The duration of application of the acid did not affect significantly this parameter of evaluation, but in groups 15 and 30, the bonearea covered more than tripled from 24 to 72 hours (p <0.01), with about 70 % of the area covered by cells, versus 30% in the control group. It was concluded that bone demineralization in the studied conditioning times provides a substrate on which cells acquire pre-osteoblastic morphology compatible with more advanced stage of differentiation, promoting greater coverage area, which increases the potential for deposition of new bone on these surfaces compared to the tissue-air basis.

Introduction: Cough is the commonest reason for which medical advice is sought. In assessment of chronic cough and in developing anti-tussive medications, inhalational cough challenges with capsaicin and citric acid are commonly employed. However the ability of these inhalational cough challenges to distinguish health and disease is not clear and it is not known which end point is best in making such assessments. Methods: Subjects belonging to five different categories (healthy volunteers, subjects with COPD, asthma, healthy current smokers and chronic cough) were compared with each another by using the standard cough challenges employing Capsaicin and Citric acid and also by using newer inhalational cough challenge agents such as prostaglandin E2 and bradykinin. In addition adaptation to repeated inhalations of tussive agents was also assessed. The relationship between the cough reflex sensitivity as gauged by using inhalational cough challenge tests and objective cough recording was explored in all five groups. Finally the change in C5 in Capsaicin evoked cough by using a substance to block TRPV1 channel and its effect on objective cough recording was assessed in subjects with chronic cough. Results: Different tussive agents have different abilities to distinguish between different diagnostic categories and a combination of inhalational cough challenge tests have a better accuracy of predicting diagnostic groups as compared to one on its own. There are significant differences in the rates of adaptation to repeated inhalations of PGE2 and there is a significant reduction in cough response over period of time in all disease groups. Using the TRPV1 antagonist resulted in a modest increase in the Log C5 concentration of capsaicin but this was not matched by a change in objective cough recording or CQLQ scores. Conclusions: The different abilities of tussive agents to distinguish between different diagnostic categories suggest that the information conveyed by the one inhalational cough challenge test is different from that by another test. The choice of the inhalational cough challenge test should therefore depend on which groups are included in the study. There was no significant difference in the rate of adaptation to prolonged challenge with citric acid or capsaicin and no significant correlation of the magnitude of adaptation with objective cough recording suggesting that this is unlikely to be responsible for the increased cough rates seen in diseases such as chronic cough, COPD or asthma. The TRPV1 antagonist did not result in a significant change in objective cough recording or CQLQ scores. The change in C5 with the TRPV1 antagonist was however modest and this may be reason for this study failing to show a relationship between these different measures.

[EN] Different strategies were used to improve physical properties of corn starch based films, with glycerol (30%) as plasticizer, based on increasing their hydrophobic character in order to reduce the materials' water sensitivity. Starch was blended with different components (surfactants and more hydrophobic polymers), with and without compatibilizers, to obtain blend films through different processing techniques (casting, melt blending, compression molding and extrusion). Bilayer film formation by compression molding with starch and poly(e-caprolactone) (PCL) was also studied. The addition of surfactants to starch films obtained by casting gave rise to a decrease in water vapor permeability (WVP), but an increase in the film fragility was observed. Surfactants with lower hydrophilic-lipophilic balance (HLB), solid at room temperature, promoted a fine microstructure in the matrix with smaller lipid particle, which enhanced water vapor barrier properties. Thermo-processing was used to obtain the other films due to its broader industrial application. Starch blends with hydroxypropyl methylcellulose (HPMC) showed an HPMC dispersed phase in the starch matrix and better water barrier properties, but they were more permeable to oxygen, especially when they contained citric acid (CA) as compatibilizer. CA induced cross-linking in the polymeric matrix, thus slightly increasing film hardness, but decreasing its extensibility. The incorporation of PCL in different ratios to starch films obtained by compression molding gave rise to polymer phase separation, although a small PCL miscibility in the starch rich phase was detected, which reduced the glass transition temperature of the starch phase. The structural heterogeneity and lack of interfacial adhesion between polymers gave rise to fragile films. Nevertheless, small amounts of PCL (10%) reinforced the matrix (increase in the elastic modulus). When the PCL ratio increased, WVP was reduced but oxygen permeability increased. The incorporation of CA as compatibilizer of these blends provoked an increase in the water solubility of the films, by hydrolysis, and improved the mechanical properties of the films when PCL ratio was low (10%), but it did not affect the film barrier properties. The incorporation of polyethylene glycol (PEG 4000) to the blends with a low proportion of PCL did not imply an improvement in the film properties, since it promoted phase separation. Starch-PCL blends with 1:0.05 mass ratio, without compatibilizer, were quite homogenous and exhibited good mechanical properties and stability. In order to incorporate greater amounts of PCL, thus improving film hydrophobicity and stability, PCL was chemically modified by grafting glycidyl methacrylate or glycidyl methacrylate and maleic anhydride (PCL-g), to be used as compatibilizers. Films with 20 % PCL and 2.5 or 5 % of PCL-g showed very good mechanical and barrier properties and stability, inhibiting starch retrogradation. Their barrier properties met the food packaging requirements for a wide number of food products. Bilayer films obtained by compression molding of starch (or starch with 5% PCL) and PCL layers showed very low WVP and oxygen permeability and adequate mechanical properties. The adhesion of bilayers was greatly improved by the application of ascorbic acid and, especially, potassium sorbate, as aqueous solutions, at the interface before compression molding. These compounds, in turn, imparted antioxidant and antimicrobial properties, respectively, to the films, thus improving their potential use as active packaging material for food uses. / [ES] Se han utilizado diversas estrategias para mejorar las propiedades físicas de films a base de almidón de maíz, con glicerol (30 %) como plastificante, basadas en el incremento de su carácter hidrofóbico, para reducir su sensibilidad al agua. El almidón se mezcló con diferentes compuestos (surfactantes y polímeros más hidrofóbicos), con y sin compatilizadores, para la obtención de films mixtos por diferentes técnicas de procesado (casting, mezclado en fundido, moldeo por compresión y extrusión). Se estudió también la formación de films bicapa almidón-poli-e-caprolactona (PCL) mediante moldeo por compresión. La adición de surfactantes a los films de almidón elaborados por casting dio lugar a una disminución de su permeabilidad al vapor de agua (WVP), pero aumentó su fragilidad. Los surfactantes con menor balance hidrófilo-lipófilo (HLB), y sólidos a temperatura ambiente, proporcionaron una microestructura de los films con menor tamaño de partícula, que potenció las propiedades barrera al vapor de agua. Por su mayor aplicabilidad industrial, se emplearon técnicas de termo-procesado para la obtención del resto de films estudiados. Los obtenidos por mezcla con hidroxipropil metilcelulosa (HPMC) presentaron una fase dispersa de HPMC en la matriz de almidón y mejores propiedades barrera al vapor de agua, pero fueron algo más permeables al oxígeno, sobre todo cuando se incorporó ácido cítrico (CA) como compatibilizador. Este provocó entrecruzamiento en la matriz polimérica, incrementado ligeramente su dureza y reduciendo su extensibilidad. La incorporación de PCL en diferentes proporciones a los films de almidón obtenidos por termo-compresión, dio lugar a la separación de fases polímericas, detectándose una pequeña miscibilidad de la PCL en la fase rica en almidón que redujo la temperatura de transición vítrea de la fase amilácea. La heterogeneidad de su estructura y la falta de adhesión entre fases dio lugar a films demasiado frágiles, aunque en pequeña proporción (10%), la PCL reforzó la matriz (aumentó el módulo de elasticidad). Al aumentar la proporción de PCL, disminuyó la WVP de los films, pero aumentó la permeabilidad al oxígeno. La incorporación de CA como compatibilizador de estas mezclas aumentó la solubilidad en agua de los films por efecto de hidrólisis y supuso una mejora en las propiedades mecánicas de los films con baja proporción de PCL (10 %), pero no afectó a sus propiedades barrera. La incorporación de polietilenglicol (PEG 4000) a las mezclas con baja proporción de PCL no mejoró las propiedades de los films, potenciando la separación de fases. Las mezclas almidón:PCL con proporción másica 1:0.05, sin compatibilizador, fueron bastante homogéneas y exhibieron buen comportamiento mecánico y estabilidad. Para incorporar una mayor proporción de PCL, y mejorar la hidrofobicidad y estabilidad de los films, se modificó la PCL por reacción con glicidil metacrilato o anhídrido maleico y glicidil metacrilato (PCL-g), para su uso como compatibilizadores. Los films con 20% de PCL y 2.5 y 5 % de los PCL-g presentaron muy buenas propiedades mecánicas y de barrera al vapor de agua y a los gases y buena estabilidad al inhibir la retrogradación del almidón. Sus propiedades de barrera cumplieron con los requisitos de envasado de un número importante de productos alimentarios. La obtención de films bicapa por termo-compresión a partir de almidón (o almidón con 5% PCL) y PCL proporcionó un material con muy baja permeabilidad al vapor de agua y al oxígeno y buenas propiedades mecánicas. La adhesión entre las capas mejoró en gran medida con la incorporación de ácido ascórbico, y sobre todo de sorbato potásico, en la interfase en forma de disolución acuosa antes de la termo-compresión. Estos compuestos impartieron, a su vez, propiedades antioxidantes y antimicrobianas, respectivamente, a los films, mejorando su uso potencial para el envasad / [CAT] S'han utilitzat diverses estratègies per a millorar les propietats físiques de films a base de midó de dacsa, amb glicerol (30 %) com plastificant, basades en l'increment del seu caràcter hidrofòbic, per a reduir la seua sensibilitat a l'aigüa. El midó es va mesclar amb diferents compostos (surfactants i polímers més hidrofòbics), amb i sense compatibilitzadors, per l'obtenció de films mixtos mitjançant diferents tècniques de processat (càsting, mesclat en fos, modelatge per compressió i extrusió). Es va estudiar també la formació de films bicapa midó-poli-e-caprolactona (PCL) mitjançant modelatge per compressió. L'addició de surfactants als films de midó elaborats per càsting va donar lloc a una disminució de la seua permeabilitat al vapor d'aigüa (WVP), però va augmentar la seua fragilitat. Els surfactants amb menor balanç hidròfil-lipòfil (HLB), i sòlids a temperatura ambient, varen proporcionar una microestructura dels films amb menor grandària de partícula, que varen potenciar les propietats barrera al vapor d'aigüa. Per la seua major aplicabilitat industrial, es van emprar tècniques de termo-processat per l'obtenció de la resta de films estudiats. Aquells obtinguts per mescla amb hidroxipropil-metilcellulosa (HPMC) varen presentar una fase dispersa de HPMC en la matriu de midó i millors propietats barrera al vapor d'aigüa, però varen ser un poc més permeables a l'oxigen, sobretot quan es va incorporar àcid cítric (CA) com compatibilitzador. Aquest va provocar entrecreuament en la matriu polimérica, incrementant lleugerament la seua duresa i reduïnt la seua extensibilitat. La incorporació de PCL en diferents proporcions als films de midó obtinguts per termo-compressió, va donar lloc a la separació de fases polimèriques, detectant-se una xicoteta miscibilitat de la PCL en la fase rica en midó que va reduir la temperatura de transició vítria de la fase amilàcea. L'heterogeneïtat de la seua estructura i la falta d'adhesió entre fases va donar lloc a films massa fràgils, encara que en xicoteta proporció (10%), la PCL va reforçar la matriu (augmentant el mòdul d'elasticitat). Al augmentar la proporció de PCL, va disminuir la WVP dels films, però va augmentar la permeabilitat a l'oxigen. La incorporació de CA com compatibilitzador d'aquestes mescles va augmentar la solubilitat en aigüa dels films per efecte d'hidròlisi i va suposar una millora en les propietats mecàniques dels films amb baixa proporció de PCL (10 %), però no va afectar les propietats barrera. La incorporació de polietilenglicol (PEG 4000) a les mescles amb baixa proporció de PCL no va millorar les propietats dels films, potenciant la separació de fases. Les mescles midó:PCL amb proporció màssica 1:0.05, sense compatibilitzador, varen ser prou homogènies i varen exhibir un bon comportament mecànic i una bona estabilitat. Per a incorporar una major proporció de PCL i millorar l'hidrofobicitat i estabilitat dels films, es va modificar la PCL per reacció amb glicidil metacrilat o anhídrid maleic i glicidil metacrilat (PCL-g), per al seu ús com compatibilitzadors. Els films amb 20% de PCL i 2.5 i 5 % dels PCL-g varen presentar molt bones propietats mecàniques i de barrera al vapor d'aigüa i als gasos i bona estabilitat al inhibir la retrogradació del midó. Les seues propietats de barrera varen complir amb els requisits d'envasament d'un nombre important de productes alimentaris. L'obtenció de films bicapa per termo-compressió a partir de midó (o midó amb 5% PCL) i PCL va proporcionar un material amb molt baixa permeabilitat al vapor d'aigüa i al oxigen i bones propietats mecàniques. L'adhesió entre les capes va millorar en gran mesura amb l'incorporació d'àcid ascòrbic, i sobretot de sorbat de potassi, en la interfase en forma de dissolució aquosa abans de la termocompressió. Aquestos compostos varen impartir, a la vegada, propietats antioxidants i antimicrobianes, respec / Ortega Toro, R. (2015). DESARROLLO Y CARACTERIZACION DE PELÍCULAS DE ALMIDÓN DE MAÍZ POR MEZCLADO CON COMPUESTOS MÁS HIDROFÓBICOS [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/52521 / TESIS

In this work synthesis of structure cobaltites based on Ca-Co-O system is discussed. As major way of synthesis was chosen citric acid method. The document is devided into theoretical and experimental part and also into discussion of observed results. Main focus of literary research is general utilization and function of thermoelectric materials, related thermoeletric effects according to structural defects in crystals. Also topic of cobaltite ceramics is described. Due to the fact that calcium-cobalt oxides are conductive, their use is point of interest in high-temperature and energy applications. During experiments differential thermal and thermogravimetric analysis (TG-DTA), X-Ray diffraction, heat microscopy and scanning electron microscopy were used.

<p>Transport of gasses and liquids through polymers and composites is an important factor to be considered when designing a material for structure and packaging applications. For structural engineering applications, more focus has been given to the transportation of water, vapor and organic liquids rather than gases as diffusion of these liquids into the polymers and polymer-based composites can significantly lower service life. In addition, much attention has been given to the leaching of unreacted reactant molecules, solvents, additives, degradation products from the polymers and composites to the atmosphere (water, soil etc.). We studied the transport of volatile organic compounds and water in cured-in-place-pipe (CIPP) (a representative of FRPC) and gas permeability of highly engineered cellulose nanocrystals (CNC) films.</p> <p>Cured-in-place-pipe (CIPP) is a popular technology which uses fiber reinforced polymer composite to repair sanitary sewer, stormwater, and drinking water pipe. The liner is installed in the field and exposed to flowing water immediately after installation (curing of the liner) is done. Curing conditions dictate liner properties as undercured liners can contain unreacted styrene monomers, additives, degradation products. These agents can leach out and enter the environment (soil, water, air). The objective of this work was to investigate the curing behavior, volatile content, thermal stability of steam-cured and UV-cured CIPP liners collected from Indiana and New York installation sites. The liner specimens were also exposed to water and other aggressive environmental conditions (saltwater, concrete pore solution at 50 °C) to explore the leaching of unreacted styrene and other organic chemicals from the liners. The influence of transportation of water, salt solution and pore solution through liners on mechanical and thermo-mechanical properties was also examined to study the durability of the liners. Study suggested that the durability of the liners depends on the curing condition and exposed environment conditions.</p> <p>The function of polymer packaging materials is mainly to inhibit gas and moisture permeation through the films. Cellulose nanocrystals (CNCs) have drawn growing interest for the packaging due to their non-toxicity, abundance in nature, biodegradability and high barrier properties. The objective of this work was to corelate the alignment of CNC with free volume and barrier performance of the film. Furthermore, citric acid (CA) was added to the CNC suspensions with varying quantity to explore the effect of CA on coating quality and barrier performance of CNC coated polypropylene (PP) film. Study revealed that CA addition in CNC suspension can enhance the hydrophobicity and gas barrier performance of coated PP films while retaining the high optical transparency. </p>

This thesis is focused on carbide ceramics synthesis, more specifically on the synthesis of a Ti2AlC MAX Phase carbide using solution chemistry rather than powder metallurgy. Chloride and nitrate precursors have been used as a source of metals and citric acid as a source of carbon for carbothermal reduction and as a complexing agent. A new route of precursor synthesis has been developed based on peroxo-titanic acid, which helps retain aluminium. The syntheses were performed using the SPS facility to ensure high heating rates. Al4C3 and TiC carbides and their mixtures were prepared successfully. However, the Ti2AlC phase was not synthesized under used conditions. The phase composition, structure and grain sizes of the samples were investigated by powder X-ray diffraction, X-ray fluorescence and electron microscopy. The contents of carbon in the precursors were determined by thermogravimetric analysis.

Eine der für die biotechnologische Nutzung interessanten Eigenschaften der Hefe Yarrowia (Y.) lipolytica ist ihr Vermögen, unter bestimmten Kultivierungsbedingungen große Mengen an organischen Säuren, darunter auch Citronensäure (CS), ins extrazelluläre Medium zu sekretieren. Aufgrund ihrer Apathogenität, ihres breiten Substratspektrums und ihrer guten molekulargenetischen und verfahrenstechnischen Handhabbarkeit, stellt sie einen idealen Mikroorganismus zur biotechnologischen Gewinnung von Citronensäure dar. Bei der durch eine Stickstofflimitation ausgelösten Überproduktion von CS mit Y. lipolytica kommt es parallel auch zur Ausscheidung von Isocitronensäure (ICS), deren Anteil am Gesamtsäureprodukt in Abhängigkeit von der C-Quelle in Wildtypstämmen zwischen 10 % (Glucose, Saccharose, Glycerol) und 40-55 % (Pflanzenöle, Alkan) liegt. In der Literatur beschriebene Mutantenstämme von Y. lipolytica besitzen ein von Wildtypstämmen abweichendes Produktmuster und können sowohl weniger (2-5 % auf Glucose, 5-10 % Alkan und Pflanzenöl) als auch mehr ICS (15-35 % Glu¬cose, 65-75 % Alkan, Ethanol bzw. Pflanzenöl) sekretieren. Die gezielte Überexpression des für die Isocitratlyase codierenden Gens ICL1 durch die Erhöhung der Kopiezahl führte zu einer drastischen Erhöhung der Enzymaktivität in den entsprechenden ICL1 multicopy Transformanden (10-15fach gegenüber Wildtyp) aufgrund des Gen-Dosis-Effektes. Auf den getesteten hydrophilen C-Quellen Glucose, Glycerol und Saccharose verringerte sich der ICS-Anteil von durchschnittlich 10-12 % auf 3-5 %, auf den hydrophoben C-Quellen Hexadecan und Sonnenblumenöl sogar von durchschnittlich 40-55 % auf Werte um 5-10 %. Im Ergebnis dieser Untersuchungen entstand ein Patent (DE10333144A1), welches ein Verfahren zur Gewinnung von CS mit einer genetisch veränderten Hefe Y. lipolytica beschreibt. Die Zerstörung des Leserahmens des ICL1 Gens in Mutantenstämmen bewirkte das Ausbleiben der Synthese einer funktionell aktiven Isocitratlyase, was den Verlust der Fähigkeit zur Verwertung gluconeogenetischer C-Quellen wie Ethanol, Alkan und Pflanzenölen zur Folge hatte. Auf Glucose bzw. Glycerol zeigten diese Mutantenstämme im Vergleich zum Wildtypstamm jedoch nur eine geringe Erhöhung des ICS-Anteils um durchschnittlich 2-5 Prozentpunkte. Die Zerstörung des Leserahmens des IDP2 Gens, codierend für die NADP-abhängigen Isocitratdehydrogenase, führte zur Glutamat-Auxotrophie des entsprechenden Mutantenstammes auf allen getesteten C-Quellen. In der Produktbildung zeigte diese Mutante im Vergleich zum Wildtypstamm eine Verringerung des ICS-Anteils um durchschnittlich 2-4 Prozentpunkte. Es konnte gezeigt werden, dass Saccharose ein geeignetes Substrat zur Gewinnung von CS mit rekombinanten Stämmen von Y. lipolytica darstellt, die das für die Invertase codierende SUC2 Gens aus Saccharomyces cerevisiae exprimieren. Natürlicherweise kann Y. lipolytica diesen Zucker aufgrund des Fehlens des Enzyms Invertase nicht verwerten. Im Schüttelkolben wurden aus 100 g/l Saccharose unter nicht optimierten Bedingungen bereits 56 g/l CS+ICS gewonnen. Nach der Optimierung durch die Reduktion des für die Invertaseexpression durch pXPR2 notwendigen Peptonanteils von 1,7 auf 0,4 g/l erhöhte sich die Produktkonzentration auf 77 g/l. Die Übertragung des Produktionsprozesses in den Bioreaktor hatte die Verdopplung der Produktbildungsraten (RZA von 0,4 auf 0,85 g/l*h, r von 46 auf 89 mg/g*h) zur Folge, bedingt durch die Aufhebung der Sauerstofflimitation. Die Steigerung der Invertaseaktivität, die sich unter Bioreaktorbedingungen als ein Limi¬tationsfaktor her¬ausstellte, konnte durch die Anhebung des pH-Wertes von 5,0 auf 6,0 bzw. 6,8 er¬reicht werden. Dadurch konnten die Produktbildungsrate RZA um bis zu 80 % von 0,42 auf 0,76 g/l*h, die biomassespezifische Produktbildungsge¬schwin¬digkeit r um bis zu 70 % von 0,06 auf 0,1 g/g*h und die Ausbeute um bis zu 64 % von 0,5 auf 0,82 g/g gesteigert werden. Einen weiteren Limitationsfaktor für den CS-Bildungsprozess aus Saccharose stellt bei ausreichender Invertaseexpression offenbar die Aufnahme von Glucose und Fructose dar. Die Hefe Y. lipolytica zeigte höchste Produktbildungsraten aus Pflanzenölen, wie Sonnenblumen- oder Rapsöl, als nachwachsende Rohstoffe. Um zu prüfen, ob die Produktivität der CS-Bildung aus Pflanzenölen mit Y. lipolytica gesteigert werden kann, sollte die Triglyceridverwertung durch die Erhöhung der extrazellulären Lipaseaktivität verbessert werden. Dazu wurden zum einen Insertionsmutantenstämme, die auf eine erhöhte extrazelluläre Lipaseaktivität im Plattentest hin selektiert wurden, charakterisiert. Zum anderen wurde das für die extrazelluläre Lipase codierende LIP2 Gen in Y. lipolytica überexprimiert. Die erhaltenen LIP2 multicopy Transformanden zeigten eine bis zu 400fach erhöhte Lipaseaktivität im Vergleich zum Wildtypstamm (von 400 U/l auf bis zu 150000 U/l). Eine Verbesserung der Triglyceridverwertung aufgrund der Erhöhung der extrazellulären Lipaseaktivität in den untersuchten Insertionsmutanten und LIP2 multicopy Transformanden wurde nicht festgestellt. Die erhaltenen Daten für die Produktbildungsrate RZA (0,9-1,1 g/l*h), die biomassespezifische Produktbildungsgeschwindigkeit r (0,08-0,14 g/g*h) und die Ausbeuten (1,3-1,5 g/g) waren innerhalb der untersuchten Stämme vergleichbar und ließen keine verbesserte Produktbildung erkennen. Der geschwindigkeitsbestimmende Schritt liegt offenbar nicht bei der Hydrolyse der Triglyceride durch Lipasen, sondern bei der Aufnahme und dem Transport der Fettsäuren und/oder deren Katabolismus.

Mood disorders are serious diseases. Nevertheless, their pathophysiology is not sufficiently clarified. Biological markers that would facilitate the diagnosis or successful prediction of pharmacotherapy are still being sought. The aim of the study was to find out whether mitochondrial functions are affected by antidepressants, mood stabilizers and depression. Our research is based on recent hypotheses of mood disorders, the advanced monoamine hypothesis, the neurotrophic hypothesis, and the mitochondrial dysfunction hypothesis. We assume that impaired function of mitochondria leads to neuronal damage and can be related to the origin of mood disorders. Effects of antidepressants and mood stabilizers on mitochondrial functions can be related to their therapeutic or side effects. In vitro effects of pharmacologically different antidepressants and mood stabilizers on the activities of mitochondrial enzymes were measured in mitochondria isolated from pig brains (in vitro model). Activity of monoamine oxidase (MAO) isoforms was determined radiochemically, activities of other mitochondrial enzymes were measured spectrophotometrically. Overall activity of the system of oxidative phosphorylation was measured electrochemically using high- resolution respirometry. Methods were modified to measure the same...

The report summarizes the results obtained by the Institute of Resource Ecology of the Helmholtz-Zentrum Dresden-Rossendorf within the BMWi-financed Joint Research Project “Geochemical retention of radionuclides on cement alteration phases (GRaZ)”. The project focused on the retention behavior of Ca-bentonite and cementitious material, both constituents of the geo-engineered barrier of deep geological repositories for high-level radioactive waste, towards radionuclides. Specifically, the influence of increased salinities and of hyperalkaline conditions on interaction processes in the system radionuclides – organics – clay/cementitious materials – aquifer was studied. For this purpose, complexation, sorption and desorption studies were performed at alkaline to hyperalkaline pH conditions (pH 8-13) and under variation of the ionic strength (0.1 to 4 M) applying complex solution compositions. For the U(VI) citrate system molecular structures dominating in the pH range 2-9 were studied spectroscopically (NMR, UV-Vis, FT-IR). As dominating species 2:2, 3:3, 3:2 and, above critical concentrations also 6:6 and 9:6 U(VI) citrate complexes were identified or confirmed and complex formation constants were determined. U(VI) sorption on Ca-bentonite at (hyper)alkaline conditions in mixed electrolyte solutions was studied by means of batch sorption experiments. The U(VI) retention on Ca-bentonite was shown to be very effective at pH>10, even in the presence of carbonate and despite the prevalence of anionic aqueous uranyl species. The presence of two independent U(VI) surface complexes on Ca-bentonite at pH 8-13 was shown by site-selective TRLFS and EXAFS spectroscopy. The sorption of anionic uranyl hydroxide complexes to the mineral surface was shown to be mediated by calcium cations. In further experiments, the effect of isosaccharinic acid (ISA) and polycarboxylate ether (PCE) on U(VI) and Eu(III) sorption, respectively, on Ca-bentonite was studied. An effect of ISA on U(VI) sorption on Ca-bentonite only occurs when ISA is present in very high excess to U(VI). The effect of PCE, as a commercial cement superplasticizer, on Eu(III) sorption onto Ca-bentonite was negligible already at moderate ionic strengths. The retention of U(VI) and Cm(III) by various C-(A-)S-H phases, representing different alteration stages of concrete, was studied by batch sorption experiments. Sorbed or incorporated actinide species were identified by TRLFS. The stability of U(VI) and Cm(III) doped C-(A-)S-H phases at high ionic strengths conditions was studied in solutions simulating the contact with North German claystone formation water. Potential changes of actinide speciation as well as formation of secondary phases due to leaching effects were followed spectroscopically. The results of this project show that both bentonite and cementitious material constitute an important retention barrier for actinides under hyperalkaline conditions and increased ionic strength.