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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.
121

Germinação de sementes e conservação de orquídeas nativas das Américas /

Pereira, Suzana Targanski Sajovic. January 2020 (has links)
Orientador: Kathia Fernandes Lopes Pivetta / Resumo: A propagação in vitro e conservação ex situ, são técnicas, que podem ser aprimoradas através da escolha adequada da fonte luminosa, das formulações do meio de cultivo e de crioprotetores. O presente estudo teve por objetivos: (i) estudar fontes de luz a partir de lâmpadas fluorescentes e diodos emissores de luz (LEDs) e formulações de meio de cultivo na germinação e no desenvolvimento inicial da espécie de orquídea Brassavola perrinii e (ii) avaliar a eficiência da solução vitrificante (PVS2) combinada ao floroglucinol 1% em nitrogênio líquido para a criopreservação de sementes maduras das espécies Encyclia cordigera e Epidendrum ciliare. Os experimentos foram instalados em delineamento inteiramente casualizado e ambos foram duplicados. No primeiro os tratamentos foram arranjados em esquema fatorial 5x4 com cinco condições de luz: LF - lâmpada fluorescente; LB - LED branco; LA - LED azul; LV- LED vermelho e LAV – LED azul (50%) e vermelho (50%) e quatro formulações de meio de cultivo (MS, ½MS, VW e K), com quatro repetições e média de 125 sementes por parcela. Aos 90 dias após a semeadura foram avaliadas a porcentagem de germinação, de protocormos clorofilados e o desenvolvimento dos protocormos através das classes: P1, P2, P3 e P4 para cálculo do índice de desenvolvimento protocormos. No segundo experimento foram oito tratamentos: 1) germinação in vitro direta; 2) imersão direta em nitrogênio líquido, sem crioprotetores; 3) PVS2 por 60 min; 4) PVS2 por 120 min; 5) PVS2 por 1... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: In vitro propagation and ex situ conservation, are techniques that can be improved through the appropriate choice of light source, formulations of the culture medium and cryoprotectants. The aims this work was: (i) study the effect of light sources from fluorescent lamps and light-emitting diodes (LEDs) and cultivation medium formulations on the germination and initial development of Brassavola perrinii orchid and (ii) evaluate the efficiency of the vitrify solution (PVS2) combined with phloroglucinol 1% in liquid nitrogen for the cryopreservation of mature seeds of the species Encyclia cordigera and Epidendrum ciliare. The experiments were installed in a completely randomized design and both were duplicated. In the first, the treatments were arranged in a 5x4 factorial scheme with five light conditions: LF - fluorescent lamp; LB - white LED; LA - blue LED; LV- Red LED and LAV - Blue LED (50%) and red (50%), and four cultivation medium formulations (MS, ½MS, VW and K), with four replications and an average of 125 seeds per plot. At 90 days after sowing, the percentage of germination, of chlorophyll protocorms and the development of protocorms through the classes: P1, P2, P3 and P4 to calculate the protocorms development index. In the second experiment, there were eight treatments: 1) direct in vitro germination; 2) direct immersion in liquid nitrogen, without cryoprotectants; 3) PVS2 for 60 min; 4) PVS2 for 120 min; 5) PVS2 for 180 min; 6) PVS2 + floroglucinol1% for 60 min; 7... (Complete abstract click electronic access below) / Doutor
122

Accelerating treatment of radioactive waste by evaporative fractional crystallization

Nassif, Laurent 09 January 2009 (has links)
The purpose of the work described in this thesis was to explore the use of fractional crystallization as a technology that can be used to separate medium-curie waste from the Hanford Site tank farms into a high-curie waste stream, which can be sent to a Waste Treatment and Immobilization Plant (WTP), and a low-curie waste stream, which can be sent to Bulk Vitrification. The successful semi-batch crystallization of sodium salts from two single shell tank simulant solutions (SST Early Feed, SST Late Feed) demonstrated that the recovered crystalline product met the purity requirement for exclusion of cesium, sodium recovery in the crystalline product and the requirement on the sulfate-to-sodium molar ratio in the stream to be diverted to the WTP. The experimental apparatus, procedures and results obtained in this thesis on scaled-down experiments of SST Early and Late Feed simulated solutions were adapted and reproduced under hot-cell with actual wastes by our partners at Hanford. To prepare the application of the pretreatment process to pilot scale process, several varation to the feed solutions were investigated including the presence of carboxylates and amines organics compounds and solids particles. Results of the study showed that 4 organics species presented complications to the process (NTA, HEDTA, EDTA and sodium citrate) while the other species (Formate, acetate, glycolate and IDA) and solids particles did not in the conditions of the stored wastes. In this thesis, the kinetics of the crystalline species formed at the condition of the early feed certification run (66 °C and 25 g/h evaporation) were determined along with the effect of the operating temperature and evaporation rate on these kinetics. On one hand, the study of evaporation rate values ranging from 25g/h to 75g/h showed that an increase in evaporation rate increased the specific nucleation while decreasing the specific growth rate. On the other hand, experiments on operating temperature ranging from 35 °C to 75 °C displayed that the nucleation rate of all species increased with temperature at the exception of sodium carbonate monohydrate and burkeite crystals, and that the growth rate of all species increased with temperature at the exception of sodium nitrate. Furthermore, sulfate based crystals such as trisodium fluoride sulfate were only roduced at 45 °C and 75 °C. A simple steady state MSMPR population balance model was developed expressing the total population density function as the sum of the specific population density functions. The specific semi-batch crystallization kinetics were implemented in this model.
123

Elektron kryo-mikroskopické techniky v biologickém výzkumu a nanotechnologiích / Electron cryo-microscopy techniques in biological research and nanotechnologies

Mistríková, Veronika January 2011 (has links)
Preparation of biological samples for transmission electron microscopy is not a trivial task. The samples must withstand a vacuum environment present inside a microscope, and it is often necessary to use non-physiological procedures for their processing. These procedures usually involve aldehyde-based fixation, replacing water with alcohol (i.e. dehydration/substitution), and embedding into a resin, which creates support for the subsequent preparation of thin sections that can be placed into the microscope. In the last decade, the method of cryo-fixation (vitrification) using ultra-fast high-pressure freezing followed by freeze substitution and low-temperature resin embedding gained a dominant position in the cell biology research. In this way, a range of biological samples with a thicknesses up to several hundreds of micrometers was successfully vitrified to a state that was closely related to their in vivo structures. The cryo-fixation of isolated biological objects (with a limited thickness up to several micrometers) is possible in a thin layer of vitrified water by plunge freezing at ambient pressure. In combination with electron cryo-microscopy, this method has become the most effective and fundamental principle for the high-resolution studies and image analysis of fully hydrated samples...
124

Contribution of vitrification to human assisted reproduction / Apport de la vitrification à la PMA

Fasano, Giovanna 28 March 2013 (has links)
La cryopréservation, dans le domaine de la reproduction médicalement assistée, constitue depuis de nombreuses années une branche suscitant beaucoup d’intérêts et d’espoirs. En effet, de nombreuses équipes de recherche se sont attelées à mettre au point et à améliorer des protocoles permettant de conserver les gamètes, les embryons et les tissus reproducteurs.<p>Malgré le fait que la cryopréservation soit une technique très attractive, elle peut avoir des effets délétères sur les cellules. Les protocoles expérimentaux visent donc à minimiser ces effets afin d’augmenter la survie et la compétence cellulaire après décongélation.<p><p>Les deux méthodes les plus utilisées, la congélation lente et la vitrification, présentent chacune des avantages et des inconvénients. En effet, la première ne permet pas d’éliminer la cristallisation intracellulaire. Quant à la seconde, elle empêche la formation de cristaux de glace mais pourrait provoquer une toxicité due à la forte concentration des cryoprotecteurs. <p><p>Cette thèse de doctorat propose plusieurs objectifs :<p><p>•\ / Doctorat en Sciences biomédicales et pharmaceutiques / info:eu-repo/semantics/nonPublished
125

Elektron kryo-mikroskopické techniky v biologickém výzkumu a nanotechnologiích / Electron cryo-microscopy techniques in biological research and nanotechnologies

Mistríková, Veronika January 2011 (has links)
Preparation of biological samples for transmission electron microscopy is not a trivial task. The samples must withstand a vacuum environment present inside a microscope, and it is often necessary to use non-physiological procedures for their processing. These procedures usually involve aldehyde-based fixation, replacing water with alcohol (i.e. dehydration/substitution), and embedding into a resin, which creates support for the subsequent preparation of thin sections that can be placed into the microscope. In the last decade, the method of cryo-fixation (vitrification) using ultra-fast high-pressure freezing followed by freeze substitution and low-temperature resin embedding gained a dominant position in the cell biology research. In this way, a range of biological samples with a thicknesses up to several hundreds of micrometers was successfully vitrified to a state that was closely related to their in vivo structures. The cryo-fixation of isolated biological objects (with a limited thickness up to several micrometers) is possible in a thin layer of vitrified water by plunge freezing at ambient pressure. In combination with electron cryo-microscopy, this method has become the most effective and fundamental principle for the high-resolution studies and image analysis of fully hydrated samples...
126

Embryo cryopreservation and transfer to rederive a paternal rabbit line after 18 generations. Evaluation of growth and reproductive traits

Juárez Moreno, Jorge Daniel 01 September 2022 (has links)
Tesis por compendio / [ES] Para evaluar los efectos del proceso de selección en una línea paterna de conejos, se compararon los rasgos de crecimiento y rendimiento reproductivo de la descendencia actual (generación R36) en similar ambiente con una población control rederivada de embriones de una generación anterior (R18). Para reducir/evitar el efecto del proceso de criopreservación sobre los rasgos fenotípicos se rederivaron embriones de la generación actual (R36) y obtener una 3ra población (R37V). Capítulo 1, se compara la R37V y la descendencia de la R36 nacida por inseminación artificial (R37). Hubo diferencias en rasgos de crecimiento postnatal en las 3 generaciones evaluadas, pero no en el crecimiento fetal, componentes del tamaño de la camada y rasgos reproductivos. Así, los procesos de criopreservación y transferencia de embriones causan cambios en rasgos de crecimiento de poblaciones reconstituidas que influyen en las siguientes generaciones, sin producir cambios en los reproductivos. En los siguientes capítulos, para reducir/evitar los efectos del proceso de rederivación, la deriva genética y factores ambientales sobre los rasgos fenotípicos, se usó sólo poblaciones rederivadas para comparar los rendimientos reproductivos y de crecimiento. Capítulo 2, al ser los machos usados para producir dosis seminales en centros de inseminación y granjas, se evaluó si el programa de selección modificaba los rasgos seminales, el proteoma del plasma seminal y de espermatozoides, y la fertilidad del semen al usarla en inseminación artificial. Se analizó el proteoma del plasma seminal y espermatozoides de machos maduros de c/grupo y se prepararon dosis seminales para inseminación. Sólo el porcentaje de espermatozoides anormales mostró diferencias, presentando los R21 menos espermatozoides anormales que los R39. El análisis discriminante (DA-PLS) mostró efecto de la generación para el proteoma plasmático y espermático. En plasma seminal, se reportaron 64 proteínas diferencialmente expresadas y 56 sobreexpresadas en R39 (87,5%). Del proteoma de espermatozoides 132 diferencialmente abundantes y 89 sobreexpresadas en R39 (67,4%). A pesar de las diferencias en importantes proteínas relacionadas con la capacitación, la motilidad, la inmunoprotección de espermatozoides y la fecundación, no hubo diferencias en fertilidad y prolificidad con las dosis seminales para inseminación. Capítulo 3, se analizó el efecto de la selección por ganancia media diaria de peso (GMD) post-destete después de 37 generaciones. Tras 2 generaciones post rederivación (R21 vs. R39), todos los caracteres evaluados mostraron progreso resultado de la selección, y no afecta a los parámetros estimados de la curva de crecimiento de Gompertz. Los resultados demuestran que el programa de selección mejoró la GMD sin variar el peso corporal adulto, pero tras 37 generaciones de selección, este carácter parece agotado. Capítulo 4, comparamos los parámetros reproductivos de conejas entre las poblaciones rederivadas y control. Los rasgos de desarrollo prenatal y los componentes del tamaño de camada se midieron en la 2da generación post rederivación (R20 y R38). Así la selección por GMD no tiene efectos adversos sobre los componentes del tamaño de la camada, y el área del saco fetal al día 12 de gestación, área de la placenta fetal y la longitud cráneo-rabadilla del feto al 19 de gestación fueron mayores en R38. Resultados muestran que la selección por GMD no afecta negativamente el rendimiento reproductivo. Conclusión, el estudio demuestra que los efectos de la criopreservación sobre los rasgos de crecimiento persisten dos generaciones post rederivación. Además, la línea muestra signos de agotamiento del progreso genético quizás por el bajo rendimiento reproductivo y elevada mortalidad postnatal. La selección por GMD influyó en cambios del crecimiento fetal y del proteoma del eyaculado, sin afectar al rendimiento reproductivo de hembras ni la fertilidad y prolificidad de las dosis seminales de machos. / [CA] Per avaluar els efectes del procés de selección en una línia paterna de conills, es van comparar els trets de creixement i el rendiment reproductiu de la descendència de la generació actual (R36) sota el mateix entorn amb una població control derivada dels embrions emmagatzemats d'una generació anterior (R18). Per reduir/evitar l'efecte del procés de criopreservació embrions de la generació actual (R36) es van criopreservar i transferir (rederivar) per obtenir una 3a població (R37V). Capítol 1, es compara la generació R37V i la descendència de la 36a generació nascuda per inseminació artificial (R37). Hi ha diferències en els trets de creixement postnatal a les tres generacions avaluades. Tot i que el creixement fetal, els components de la mida de la ventrada i els trets reproductius no van mostrar diferències. La rederivació provoquen canvis en els trets de creixement de les poblacions reconstituïdes que influeixen en les generacions següents, sense canvis en els trets reproductius. En els capítols següents, per reduir/evitar els efectes del procés de rederivació, la deriva genètica i els factors ambientals sobre els trets fenotípics, es van utilitzar les poblacions rederivades per comparar els rendiments reproductius i de creixement. Capítol 2, ja que els mascles s'utilitzaven per produir dosis de semen en centres d'inseminació i granges, es va estudiar si un programa de selecció per guany mitja de pes diari pot canviar els trets seminals, el proteoma del plasma i dels espermatozoides i la fertilitat del semen en la inseminació artificial. Només el percentatge d'espermatozoides anormals mostra diferències significatives, R21 presentant menys espermatozoides anormals que R39. L'anàlisi discriminant (DA-PLS) mostra efecte de la generació al proteoma del plasma i dels espermatozoides. En plasma seminal, 64 proteïnes es van expressar de manera diferent, 56 sobre-expressades en R39 (87,5%). El proteoma de l'esperma 132 proteïnes diferencialment abundants, 89 sobre-expressades en R39 (67,4%). Tot i observar diferències en proteïnes importants relacionades amb la capacitat, la motilitat o la immunoprotecció dels espermatozoides i la fecundació, La fertilitat i la prolificitat es van detectar quan es van utilitzar dosis seminals comercials per a la inseminació. Capítol 3, vam avaluar l'efecte d'una selecció a llarg termini per a l'augment de pes mitjà diari (ADG). Després de dues generacions d'ambdues poblacions rederivades (R21 vs. R39), tots els trets avaluats mostra algun progrés. Aquesta resposta no sembla afectar els paràmetres estimats de la corba de creixement de Gompertz. Resultats demostra que el programa de selecció havia millorat l'ADG sense variacions en pes corporal adult, però després de 37 generacions de selecció, aquest tret sembla esgotat. Capítol 4, compara els trets reproductius entre poblacions femenins entre ambdues poblacions (rederivades i control). El desenvolupament fetal i els components de la mida de la ventrada es mesura els trets a la segona generació després de la rederivació (R20 i R38). Resultats suggereix que la selecció per ADG no té cap efecte advers sobre els components de la mida de la ventrada i la zona del sac fetal el dia 12 de gestació i la zona de la placenta fetal i la longitud de la corona-gropa del fetus el dia 19 de gestació eren més grans a la R38. La selecció per ADG no afecta negativament els components de la mida de la ventrada, el creixement fetal i el rendiment reproductiu. Nostre estudi proporciona més proves dels efectes de la criopreservació sobre els trets de creixement que persisteixen dues generacions després de la rederivació. La línia va mostrar signes d'esgotament del progrés genètic per baix rendiment reproductiu i l'alta mortalitat postnatal. La selecció per ADG va influir en els canvis en el creixement fetal i en el proteoma ejaculat, però no va afectar el rendiment reproductiu de les femelles ni la fertilitat i la prolificitat de les dosis seminals dels mascles. / [EN] To evaluate the effects of the selection process in a paternal line of rabbits, growth traits and reproductive performance from the offspring of the current generation (R36) were compared under the same environment with a control population rederived from embryos stored of a previous generation (R18). To reduce or avoid the effect of the cryopreservation process on phenotypic traits embryos of current generation (R36) were cryopreserved and transferred to obtain a third population (R37V). In chapter 1, R37V generation and offspring of 36th generation born by artificial insemination (generation R37) were compared. Differences in postnatal growth traits were observed in the three generations assessed. Although foetal growth, litter size components and reproductive traits did not show significant differences. In conclusion, cryopreservation and embryo transfer processes cause changes in growth traits of reconstituted populations that influence the following generations, without changes in reproductive traits. In the following chapters, to reduce or avoid the effects of the rederivation process, genetic drift and environmental factors on phenotypic traits, only the rederived populations were used to compare reproductive and growth performances. In chapter 2, considering that males were used to produce semen doses at insemination centres and farms, we studied whether a programme of selection by daily gain changed the seminal traits, plasma and sperm proteome and the fertility of semen when used in artificial insemination. Seminal plasma and sperm proteome from mature males of each group were analysed and semen doses were used to inseminate females. Only the percentage of abnormal sperm showed significant differences, R21 presented fewer abnormal sperm than R39. The discriminant analysis (DA-PLS) showed an effect of the generation for plasma and sperm proteome. In seminal plasma, 64 proteins were differentially expressed, 56 were overexpressed in R39 (87.5%). Sperm proteome reported 132 differentially abundant proteins, 89 were overexpressed in R39 (67.4%). Despite differences in important proteins related to capacitation, sperm motility or immunoprotection and to the fertilization process, no differences in fertility and prolificacy were detected when commercial seminal doses were used for insemination. In chapter 3, we evaluated the effect of a long-term selection for post-weaning average daily weight gain (ADG) over 37 generations. After two generations of both rederived populations (R21 vs. R39 generations), all evaluated traits showed some progress as a result of the selection. This response does not seem to affect the estimated Gompertz growth curve parameters. Results demonstrated that the selection programme had improved ADG without variations in adult body weight but, after 37 generations of selection, this trait seems exhausted. In chapter 4, we compared female reproductive traits between both rabbit populations (rederived and control). Foetal growth and litter size traits were measured in the second generation after rederivation (R20 and R38 generations). Our study suggests that selection for growth rate has no adverse effect on litter size components and the foetal sac area at day 12 of gestation, and foetal placenta area and crown-rump length of the foetus at day 19 of gestation were higher in the R38 generation. These results show that selection for growth rate does not adversely affect on reproductive performance. In conclusion, our study provides further evidence of the effects of cryopreservation on growth traits persisting two generations after rederivation. Moreover, the paternal line showed signs of genetic progress exhaustion due to low reproductive performance and high postnatal mortality. Selection by daily weight gain influenced changes in foetal growth and ejaculate proteome, but did not affect the reproductive performance of females or the fertility of seminal doses of males. / This research was supported by AGL2017-85162-C2-1-R research project funded by Ministerio de Economía, Industria y Competitividad (MICINN, Spain). Funding for open access charge: CRUE- Universitat Politècnica de València. / Juárez Moreno, JD. (2022). Embryo cryopreservation and transfer to rederive a paternal rabbit line after 18 generations. Evaluation of growth and reproductive traits [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/185071 / Compendio

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