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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
561

Inmovilización de tirosinasa sobre ésteres cinámicos de carbohidratos fotoentrecruzados : caracterización, optimización y aplicación a la obtención de o-difenoles.

Marín Zamora, María Elisa 08 March 2013 (has links)
Se ha desarrollado un nuevo método de inmovilización de tirosinasa de champiñón, basado en la adsorción de esta enzima a un éster cinámico de un carbohidrato fotoentrecruzado, con muy buenos resultados. Se han obtenido inmovilizados de tirosinasa directamente a partir de extractos de champiñón. Se han estudiado los parámetros que afectan a la inmovilización (pH, tiempo y concentración de enzima), las características de tirosinasa inmovilizada (cantidad de enzima inmovilizada, actividad enzimática, pH y temperatura óptimos de reacción, estabilidad térmica, operacional y al almacenado), las propiedades cinéticas (constante de Michaelis, velocidad máxima y constante catalítica) de tirosinasa inmovilizada sobre distintos soportes al actuar sobre diversos sustratos y la estereoespecificidad de tirosinasa inmovilizada sobre un soporte quiral y otro no quiral respecto a los isómeros L y D y racémicos. Los conocimientos adquiridos se han aplicado con éxito a la producción de diversos o-difenoles como L-dopa, a partir de sus correspondientes monofenoles. / A new mushroom tyrosinase immobilization method consisting of tyrosinase adsorption on a photocrosslinked cinnamic carbohydrate ester has been developed with very good results. Immobilized tyrosinase was obtained directly from a mushroom extract. We studied the parameters affecting the immobilization process (pH, time and enzyme concentration), the properties of immobilized tyrosinase (quantity of immobilized enzyme, enzymatic activity, optimum pH and reaction temperature; thermal, operational and storage stability), kinetic properties (Michaelis constant, maximum steady-state rate and catalytic constant) of tyrosinase immobilized on several supports and acting over several substrates, and tyrosinase stereospecificity immobilized on a chiral and a nonchiral support acting on L and D isomers and racemics. The knowledge acquired was used to successfully produce several o-diphenols, such as L-dopa, from the corresponding monophenols.
562

Nitrogen response efficiency, nitrogen retention efficiency, and asymbiotic biological nitrogen fixation of a temperate permanent grassland site under different sward compositions and management practices

Keuter, Andreas 08 January 2013 (has links)
No description available.
563

Association entre la sclérose en plaques et le syndrome des impatiences musculaires de l'éveil : caractérisation par des études de sommeil

Proulx-Therrien, Joëlle 10 1900 (has links)
Le syndrome des impatiences musculaires de l’éveil (SIME) est un trouble sensitivo-moteur causant des perturbations du sommeil. Il fut décrit que ce syndrome est plus fréquent chez les sujets vivant avec la sclérose en plaques (SEP) que dans la population générale. L’objectif principal de ce travail est de décrire l’impact du SIME sur le sommeil des sujets avec la sclérose en plaques, comparé au sommeil de sujets avec la SEP, mais sans SIME. Des questionnaires validés et des études de polysomnographie seront utilisés pour réaliser nos objectifs. Les études de PSG de nos 49 sujets révèlent qu’indépendamment de la présence ou de l’absence du SIME, le sommeil des sujets avec la SEP est grandement perturbé. De plus, même en l’absence du SIME, les sujets avec la SEP présentent des mouvements périodiques des jambes. Cette étude démontre que le SIME se manifeste différemment dans la SEP. De plus amples recherches sont nécessaires pour mieux caractériser le SIME en SEP. / The Restless legs syndrome is a sleep related movement disorder. It causes sleep disruptions, affecting sleep quality. It has been described as being more frequent in an MS population than in the general population. Our main objective was to evaluate its impact on MS subjects’ sleep in comparison to MS subjects without RLS Validated questionnaires and polysomnography was used to achieve our objective. PSG studies of our 49 subjects revealed that independently of RLS status, MS subjects experience bad sleep quality, based on various sleep quality markers. Moreover, MS subjects without RLS also have periodic leg movements. This study reveals that RLS in MS manifests itself differently. Further research is needed to characterise RLS in MS.
564

Investigation of the Catalytic Mechanism and Biosensing Potential of Phosphotriesterases

Langley, Christopher R. 25 August 2011 (has links)
This thesis describes the characterization of SsoPox, a lactonase with promiscuous phosphotriesterase activity from the hyperthermophilic archaeon, Sulfolobus solfataricus, and the potential of the phosphotriesterase from Brevundimonas diminuta (PTEBd) to function as an organophosphate sensor. Arg-223 and Tyr-99 of SsoPox are not essential for lactonase activity, however substitution of a phenylalanine in place of Tyr-97 abolished lactonase activity while reducing paraoxonase activity by 20-fold. Substrate specificity of SsoPox can be modulated through the partial blockage of the hydrophobic binding tunnel adjacent to the active site. The specificity constant for N-(3-oxo-decanoyl)-L-homoserine lactone decreased 37-fold when a phenylalanine was introduced in place of Leu-226. PTEBd was expressed and purified from Pseudomonas putida and, like SsoPox, can be immobilized to Disruptor paper. The immobilized enzyme can be used to detect five organophosphates at concentrations as low as 50 μM. Incubation of PTEBd-immobilized sensors at different temperatures proved that the enzyme is stable for at least 40 days at 23.5 degrees Celsius without any detectable change in activity.
565

利用新式生物反應器培養動物細胞生產日本腦炎病毒 / Using a novel bioreactor to cultivate animal cell for Japanese encephalitis virus production

王琪婷, Chi-ting Wang January 1994 (has links)
摘 要 本研究主要是探討利用新式生物反應器以固定化細胞培養技術生產日本腦炎病毒(Japanese encephalitis virus;JEV)之研究,首先根據所培養細胞的生長特性與原有生物反應器之缺點,利用已改良設計之新式生物反應器,評估此新式生物反應器適用性、效能,以及所培養細胞之生長代謝情形與病毒力價。整個實驗過程大致分為幾個階段,第一個階段探討細胞固定化培養之最適化培養條件與生長代謝情形,第二個階段找出細胞固定化培養於此新式生物反應器中最佳生長狀態,最後一個階段為病毒的培養。實驗後發現Vero細胞經固定化貼附於FIBRA-CEL®載體上,可擴大培養於新式生物反應器,Vero細胞最佳生長量達到6.6×106cells/mL。希望藉由此改良之新式生物反應器提供細胞與病毒一個良好之生長培養環境,獲得高產量、品質穩定一致之細胞生物製品,以提供ㄧ設備簡單與製程操作容易、低成本、低能源消耗之細胞製品生產基座。 / Abstract In this study, we investigated the production of Japanese encephalitis virus (JEV) by the immobilized cell technology in a novel bioreactor. According to the disadvantages of original bioreactor and growth characteristics of cell culture, we evaluated the suitability and efficiency of a design-improved novel bioreactor as well as the growth and metabolic situation of cultured cells and titers of JEV. All studies including three major stages: (1) investigation of the optimal conditions and metabolic situation for the growth of immobilized cells, (2) finding the optimal conditions for the growth of immobilized cells in this novel bioreactor, and (3) growth of JEV using immobilized cells in this novel bioreactor. Our results showed that after immobilization on the FIBRA-CEL® carries, Vero cells can grow on the novel bioreactor up to the density of 6.6 × 106 cells/mL. Hopefully, the improvement of the novel bioreactor will provide an optimal growth condition for both the cells and viruses. Furthermore, it will also provide the basis for the production of cell products with advantages of simple-equipped, easy-to-operate, low cost, and low energy consumption. / 目 錄 誌謝------------------------------------------------- i 中文摘要 -------------------------------------------- ii 英文摘要 -------------------------------------------- iii 目錄 -------------------------------------------- iv 表目錄 -------------------------------------------- v 圖目錄 -------------------------------------------- vi 第一章 緒論---------------------------------------- 1 第二章 文獻探討------------------------------------ 3 第一節 日本腦炎病毒疫苗---------------------------- 3 第二節 動物細胞的培養------------------------------ 4 第三節 載體上動物細胞的培養------------------------ 5 第四節 動物細胞培養於生物反應器-------------------- 7 第三章 材料與方法---------------------------------- 10 一 細胞株的培養-------------------------------- 10 二 細胞冷凍保存與解凍培養---------------------- 10 三 細胞滾瓶培養-------------------------------- 11 四 病毒株的培養-------------------------------- 12 五 固定化載體材料製備-------------------------- 12 六 載體上細胞數的測定-------------------------- 12 七 細胞貼壁率的計算---------------------------- 13 八 生物反應器結構特性與固定化細胞培養---------- 13 九 日本腦炎病毒力價測定------------------------ 19 十 葡萄糖的測定-------------------------------- 19 第四章 結果與討論---------------------------------- 20 一 固定化載體材料比例對Vero細胞生長的影響------ 20 二 細胞貼附固定化時間對Vero細胞生長的影響------ 23 三 細胞接種量對Vero細胞生長的影響-------------- 24 四 生物反應器培養系統對Vero細胞生長的影響------ 25 五 新鮮培養基更換對Vero細胞生長的影響---------- 27 六 最適化細胞生長條件培養日本腦炎病毒---------- 29 第五章 結論與建議---------------------------------- 30 參考文獻 -------------------------------------------- 31 附錄一 PBS配製方法--------------------------------- 62 附錄二 Medium 199配製方法-------------------------- 62 附錄三 MEM medium配製方法-------------------------- 62
566

Temporal and Spatial Properties of a Yeast Multi-Cellular Amplification System Based on Signal Molecule Diffusion

Jahn, Michael, Mölle, Annett, Rödel, Gerhard, Ostermann, Kai 06 February 2014 (has links) (PDF)
We report on the spatial and temporal signaling properties of a yeast pheromone-based cell communication and amplifier system. It utilizes the Saccharomyces cerevisiae mating response pathway and relies on diffusion of the pheromone α–factor as key signaling molecule between two cell types. One cell type represents the α–factor secreting sensor part and the other the reporter part emitting fluorescence upon activation. Although multi-cellular signaling systems promise higher specificity and modularity, the complex interaction of the cells makes prediction of sensor performance difficult. To test the maximum distance and response time between sensor and reporter cells, the two cell types were spatially separated in defined compartments of agarose hydrogel (5 ´ 5 mm) and reconnected by diffusion of the yeast pheromone. Different ratios of sensor to reporter cells were tested to evaluate the minimum amount of sensor cells required for signal transduction. Even the smallest ratio, one α–factor-secreting cell to twenty reporter cells, generated a distinct fluorescence signal. When using a 1:1 ratio, the secreted pheromone induced fluorescence in a distance of up to four millimeters after six hours. We conclude from both our experimental results and a mathematical diffusion model that in our approach: (1) the maximum dimension of separated compartments should not exceed five millimeters in gradient direction; and (2) the time-limiting step is not diffusion of the signaling molecule but production of the reporter protein.
567

Nutrient release and cycling in the soils of a continental lodgepole pine (Pinus contorta Doug.) ecosystem, Bootleg Mountain, B.C.

Lamberts, Jill S. 13 October 2005 (has links)
Nutrient dynamics in a lodgepole pine forest at Bootleg Mountain, B.C., were investigated through the sampling of soil, snow and groundwater in six one-ha blocks. Nitrogen (NO3-, NH4+, TIN, TDN, TN), phosphorus (PO43-, TDP, TP), and DOC were analyzed in addition to N mineralization and nitrification. Position and dispersion statistics were computed for each variable and correlations (Pearson and Spearman) were computed for each pair of variables. The overall heterogeneities of soil, snow, and groundwater were generally lower between 1-ha blocks than between plots. Productivity in the soil was generally N-limited with low input from snow precipitation. Very little N leached from soil to groundwater. Phosphorus contents were highly variable and were the limiting nutrient in the groundwater. Rates of net and gross N mineralization and nitrification were determined using buried bags and 15N isotope dilutions. Gross rates were greater than net rates and nitrification was low relative to high immobilization rates. The N cycle appears to be tightly regulated, thus further study will be needed to monitor the impact of harvesting on N cycling.
568

Photochemical Surface Functionalization : Synthesis, Nanochemistry and Glycobiological Studies

Deng, Lingquan January 2011 (has links)
This thesis mainly deals with the development of photochemical approaches to immobilize carbohydrates on surfaces for glycobiological studies. These approaches have been incorporated into a number of state-of-the-art nanobio-platforms, including carbohydrate microarrays, surface plasmon resonance (SPR), quartz crystal microbalance (QCM), atomic force microscopy (AFM), and glyconanomaterials. All the surfaces have displayed good binding capabilities and selectivities after functionalization with carbohydrates, and a range of important data have been obtained concerning surface characteristics and carbohydrate-protein interactions, based on the platforms established. Besides, a variety of non-carbohydrate and carbohydrate-based molecules have been synthesized, during which process the mutarotation of 1-glycosyl thiols and the stereocontrol in 1-S-glycosylation reactions have been thoroughly studied. / QC 20111004
569

Nutrient release and cycling in the soils of a continental lodgepole pine (Pinus contorta Doug.) ecosystem, Bootleg Mountain, B.C.

Lamberts, Jill S. 13 October 2005 (has links)
Nutrient dynamics in a lodgepole pine forest at Bootleg Mountain, B.C., were investigated through the sampling of soil, snow and groundwater in six one-ha blocks. Nitrogen (NO3-, NH4+, TIN, TDN, TN), phosphorus (PO43-, TDP, TP), and DOC were analyzed in addition to N mineralization and nitrification. Position and dispersion statistics were computed for each variable and correlations (Pearson and Spearman) were computed for each pair of variables. The overall heterogeneities of soil, snow, and groundwater were generally lower between 1-ha blocks than between plots. Productivity in the soil was generally N-limited with low input from snow precipitation. Very little N leached from soil to groundwater. Phosphorus contents were highly variable and were the limiting nutrient in the groundwater. Rates of net and gross N mineralization and nitrification were determined using buried bags and 15N isotope dilutions. Gross rates were greater than net rates and nitrification was low relative to high immobilization rates. The N cycle appears to be tightly regulated, thus further study will be needed to monitor the impact of harvesting on N cycling.
570

Nitrogen availability and transformation in soils of acidified and nitrogen saturated mountain forest ecosystems / Nitrogen availability and transformation in soils of acidified and nitrogen saturated mountain forest ecosystems

TAHOVSKÁ, Karolina January 2012 (has links)
Nitrogen availability and transformation in acidified and N saturated soils of Czech (The Bohemian Forest, Ore Mountains) and Ukraine (Pop Ivan massif) mountain forest ecosystems were investigated. The study was primarily focused on the role of microbial immobilization in soil N retention. The study was based on field measurements (ion exchange resins), analyses of selected soil biochemical and microbial characteristics, and on laboratory experiments (15N labelling).

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