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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.
151

Melhoramento de leveduras para fermentação com alto teor alcoólico mediante hidridação e evolução adaptativa / Yeast improvement for high ethanol content fermentation by hybridization and adaptive evolution

Alexandrino, Natalia 28 June 2012 (has links)
O etanol contribui significativamente para que a matriz energética do país se apresente extremamente favorável quanto à participação da energia renovável. A demanda por este biocombustível é crescente e tecnologias que permitam a sua produção de forma sustentável é de suma importância, como a fermentação com alto teor de etanol, já empregada em alguns países. Linhagens de leveduras com tolerância a múltiplos estresses muito contribuíram para a implantação de tal tecnologia no Brasil. Neste contexto se insere o presente trabalho, o qual busca linhagens de leveduras capazes de suportar os estresses impostos por uma fermentação com alto teor alcoólico. Para tal, 3 entre as melhores linhagens industriais de Saccharomyces cerevisiae atualmente disponíveis (CAT-1, PE-2 e SA- 1), foram utilizadas num programa para a seleção de híbridos para tolerância múltipla aos estresses etanólico, osmótico, ácido, além de outros, inerentes à fermentação com alto teor de etanol. Estas linhagens foram esporuladas e dissecadas para obtenção de células haplóides, as quais foram submetidas a cruzamentos entre- e intra-linhagens. Foram conduzidos cruzamentos massais (aleatórios) cujos produtos foram submetidos à evolução adaptativa em meios com os fatores estressantes em intensidades crescentes no transcorrer de 80 gerações. Ao final da evolução buscou-se variantes prevalentes na população de híbridos, os quais foram submetidos a novos procedimentos seletivos com imposições de várias condições estressantes. Igualmente foram conduzidos cruzamentos direcionados entre haplóides mediante micromanipulação, sendo tais híbridos submetidos ao mesmo procedimento seletivo nos meios estressantes. Assim, a partir de 230 haplóides das 3 linhagens, 174 isolados (120 oriundos dos cruzamentos massais e 54 dos cruzamentos direcionados) foram pré-selecionados pela maior tolerância aos meios seletivos, tendo os seus cariótipos estabelecidos mediante a cariotipagem eletroforética. Os isolados com maior tolerância (27) foram novamente avaliados em fermentações com reciclo de células e sob condições de elevado teor alcoólico (até 14,5% v/v) em mosto de melaço e água. Em todas as etapas da seleção os isolados foram comparados com as linhagens parentais (CAT-1, PE-2 e SA-1), sendo que ao final do processo seletivo destacou-se a linhagem 35B (híbrido entre CAT-1 e PE-2) com atributos fermentativos superiores aos exibidos pelos parentais. Tais atributos fermentativos contemplaram parâmetros bioquímicos, fisiológicos e tecnológicos (rendimento em etanol, viabilidade celular, crescimento em biomassa, formação de glicerol e teores celulares de carboidratos de reserva glicogênio e trealose). Os resultados permitem sugerir que devido às características fermentativas desejáveis do híbrido 35B, o mesmo possa ser empregado no processo industrial para ser avaliado como uma promissora linhagem a conduzir a fermentação com alto teor alcoólico. / Ethanol contributes significantly to the energy country matrix, which presents itself as extremely favorable to the share of renewable energy. The demand for this biofuel is increasing and technologies for its production in a sustainable way is of paramount importance such as fermentation with very high gravity, already used in some countries. Yeast strains tolerant to multiple stresses greatly contributed to the deployment of such technology in Brazil. In this context the present work is inserted, which seeks yeast strains capable of withstanding the stresses imposed by high ethanol content fermentation. In order that, three of the best industrial strains of Saccharomyces cerevisiae currently available (CAT-1, PE-2 and SA-1), were used in a program to select hybrids with tolerance towards multiples stresses: ethanolic, osmotic and acid, besides other factors involved in a high ethanol content fermentation. These strains were sporulated and dissected to obtain haploid cells, which were submitted to inter- and intra-strains crossings. Hybrids from polycrossings (random crossings) were subjected to an adaptative evolution in media with increasing stressing action over the course of 80 generations. At the end of evolution, prevalent variants were sought in the hybrids population, and submitted to new selective procedures with several stressing conditions. In the same way, directed crossings (between identified haplois) were performed by micromanipulation, and the resulting hybrids were subjected to the same selective procedure. Therefore, from 230 haploid from the 3 parent strains, 174 were isolated (120 from polycrossings and 54 from directed crossings) and pre-selected for higher tolerance in selective media; moreover their karyotypes were established by electrophoretic karyotyping. Strains showing greater tolerance (27) were again evaluated during cell recycling fermentations with high ethanol content (up to 14.5% v/v) using must formulated with water and molasses. At all stages, the isolates were compared with the parental strains (CAT-1, PE-2 and SA-1), and at the end of the selection process, the strain 35B (hybrid between CAT-1 and PE-2) standed out with fermentative attributes higher than the parentals. The fermentative performance was assessed by biochemical, physiological and technological parameters (ethanol efficiency, cell viability, biomass gain, glycerol formation and cellular levels of reserve carbohydrates - glycogen and trehalose). The results suggest that due to desirable fermentation traits, the hybrid 35B, could be used as starter in industrial fermentation process with high ethanol content.
152

Phenotypic and genotypic characterization of white maize inbreds, hybrids and synthetics under stress and non-stress environments

Makumbi, Dan 30 October 2006 (has links)
Maize is susceptible to biotic and abiotic stresses. The most important abiotic stresses in Africa are drought and low soil fertility. Aflatoxin contamination is a potential problem in areas facing drought and low soil fertility. Three studies were conducted to evaluate maize germplasm for tolerance to stress. In the first study, fifteen maize inbred lines crossed in a diallel were evaluated under drought, low N stress, and well-watered conditions at six locations in three countries to estimate general (GCA) and specific combining ability (SCA), investigate genotype x environment interaction, and estimate genetic diversity and its relationship with grain yield and heterosis. GCA effects were not significant for grain yield across environments. Lines with good GCA effect for grain yield were P501 and CML258 across stresses. Lines CML339, CML341, and SPLC7-F had good GCA effects for anthesis silking interval across stresses. Additive genetic effects were more important for grain yield under drought and well-watered conditions. Heterosis estimates were highest in stress environments. Clustering based on genetic distance calculated using marker data from AFLP, RFLP, and SSRs grouped lines according to origin. Genetic distance was positively correlated with grain yield and specific combining ability. In the second study, synthetic hybrids were evaluated at seven locations in three countries to estimate GCA and SCA effects under low N stress and optimal conditions and investigate genotype x environment interaction. GCA effects were significant for all traits across low N stress and optimal conditions. The highest yielding synthetic hybrids involved synthetics developed from stress tolerant lines. Synthetics 99SADVIA-# and SYNA00F2 had good GCA for grain yield across low N stress conditions. Heterosis was highly correlated with grain yield. Optimal environments explained more variation than stress environments. The third study evaluated the agronomic performance and aflatoxin accumulation of single and three-way cross white maize hybrids at five locations in Texas. Inbreds CML343, Tx601W, and Tx110 showed positive GCA effects for grain yield. Significant GCA effects for reduced aflatoxin concentration were observed in lines CML269, CML270, and CML78 across locations. Differences in performance between single and three-way crosses hybrids were dependent mostly on the inbred lines.
153

The Architectural Optimization of Stretch-formed Ceramic-aluminum Microtruss Composites

Yu, Hiu Ming (Bosco) 27 November 2012 (has links)
Microtruss cellular materials have large internal surface areas and small cross-sectional strut dimensions, permitting surface modification to substantially enhance their mechanical performance. For instance, a ~400% increase in compressive strength with virtually no weight penalty can be induced by a hard anodized Al2O3 ceramic coating of only ~50 µm thickness. The present study seeks the optimal architecture of these composites by exploring three research challenges: architecture and degree of forming are interdependent due to stretch-forming, architecture and the material properties are interdependent due to work-hardening, and ceramic structural coatings add design complexity. Theoretical predictions and architectural optimizations demonstrated a potential weight reduction of ~3% to ~60% through the increase of internal truss angle for both annealed and work-hardened microtruss cores. While further validation is needed, experimental evidence in this study suggested the collapse in ceramic-aluminum microtruss composites could be considered as a mixture of composite strut global buckling and oxide local shell buckling mechanisms.
154

The Architectural Optimization of Stretch-formed Ceramic-aluminum Microtruss Composites

Yu, Hiu Ming (Bosco) 27 November 2012 (has links)
Microtruss cellular materials have large internal surface areas and small cross-sectional strut dimensions, permitting surface modification to substantially enhance their mechanical performance. For instance, a ~400% increase in compressive strength with virtually no weight penalty can be induced by a hard anodized Al2O3 ceramic coating of only ~50 µm thickness. The present study seeks the optimal architecture of these composites by exploring three research challenges: architecture and degree of forming are interdependent due to stretch-forming, architecture and the material properties are interdependent due to work-hardening, and ceramic structural coatings add design complexity. Theoretical predictions and architectural optimizations demonstrated a potential weight reduction of ~3% to ~60% through the increase of internal truss angle for both annealed and work-hardened microtruss cores. While further validation is needed, experimental evidence in this study suggested the collapse in ceramic-aluminum microtruss composites could be considered as a mixture of composite strut global buckling and oxide local shell buckling mechanisms.
155

Multifunctional Dendritic Scaffolds: Synthesis, Characterization and Potential applications

Hed, Yvonne January 2013 (has links)
The development of materials for advanced applications requires innovative macromolecules with well-defined structures and the inherent ability to be tailored in a straightforward manner. Dendrimers, being a subgroup of the dendritic polymer family, possess properties which fulfill such demands. They have a highly branched architecture with a high number of functional groups and are one of the most well-defined types of macromolecules ever synthesized. However, despite their well-defined nature and high functional density, traditional dendrimers commonly lack diverse chemical functionalities. Therefore, this thesis focuses on the synthesis of more complex dendritic materials to extend their tailoring capacity by introduction of dualfunctionalities for multipurpose actions. It covers the synthesis of dualfunctional dendrimers, dendritic modification of linear poly(ethylene glycol) polymers and cellulose surfaces, and the synthesis of linear dendritic hybrids. The building blocks enabling this synthesis, AB2C monomers, were also developed during this work. The orthogonal nature between click groups (azide, alkyne and alkene) and hydroxyl groups have efficiently been utilized for postfunctionalization by robust click chemistry and traditional esterification reactions. Furthermore, linear dendritic hybrids were synthesized, merging the properties of linear and dendritic macromolecules. The dendritic frameworks were tailored towards the production of bone fracture adhesives, novel biofunctional dendritic hydrogels, biosensors and micellar drug delivery vehicles. / Utveckling av material för avancerade applikationer kräver innovativa makromolekyler med väldefinierade strukturer och som kan skräddarsys på ett enkelt sätt. Dendrimerer är en undergrupp av dendritiska polymerer vars egenskaper uppfyller dessa krav. De har en mycket förgrenad arkitektur med många funktionella grupper och är en av de mest väldefinierade befintliga syntetiska makromolekylerna. Trots dess väldefinierade karaktär och höga funktionalitet saknar ofta traditionella dendrimerer multipla kemiska funktionaliteter. Denna avhandling fokuserar därför på syntesen av mer komplexa dendritiska material för att förbättra deras kapacitet att skräddarsys, detta görs genom att introducera fler funktionaliteter som kan utnyttjas för multipla ändamål . Avhandlingen redogör för syntesen av difunktionella dendrimerer, dendritiska modifikationer av polyetylenglykol och cellulosaytor samt syntes av traditionella dendritiska hybrider. Byggstenarna som möjliggör syntesen, AB2C monomerer, framställdes också under detta arbete. Den ortogonala karaktären mellan klick grupper (azid, alkyn och alkene) och hydroxylgrupper har utnyttjats effektivt för funktionaliseringar genom användande av robust ”Click”-kemi och traditionella esterifikationsreaktioner. Vidare tillverkades de linjära dendritiska hybrider för att kombinera egenskaperna hos både linjära och traditionella dendritiska polymerer i en och samma makromolekyl. Samtliga dendritiska strukturer skräddarsyddes för applikationer så som benlimmer, biofunktionella dendritiska hydrogeler, biosensorer och läkemedels-bärande miceller. / <p>QC 20130830</p>
156

Hardware Simulation of Fuel Cell / Gas Turbine Hybrids

Smith, Thomas Paul 06 April 2007 (has links)
Hybrid solid oxide fuel cell / gas turbine (SOFC/GT) systems offer high efficiency power generation, but face numerous integration and operability challenges. This dissertation addresses the application of hardware-in-the-loop simulation (HILS) to explore the performance of a solid oxide fuel cell stack and gas turbine when combined into a hybrid system. Specifically, this project entailed developing and demonstrating a methodology for coupling a numerical SOFC subsystem model with a gas turbine that has been modified with supplemental process flow and control paths to mimic a hybrid system. This HILS approach was implemented with the U.S. Department of Energy Hybrid Performance Project (HyPer) located at the National Energy Technology Laboratory. By utilizing HILS the facility provides a cost effective and capable platform for characterizing the response of hybrid systems to dynamic variations in operating conditions. HILS of a hybrid system was accomplished by first interfacing a numerical model with operating gas turbine hardware. The real-time SOFC stack model responds to operating turbine flow conditions in order to predict the level of thermal effluent from the SOFC stack. This simulated level of heating then dynamically sets the turbine's "firing" rate to reflect the stack output heat rate. Second, a high-speed computer system with data acquisition capabilities was integrated with the existing controls and sensors of the turbine facility. In the future, this will allow for the utilization of high-fidelity fuel cell models that infer cell performance parameters while still computing the simulation in real-time. Once the integration of the numeric and the hardware simulation components was completed, HILS experiments were conducted to evaluate hybrid system performance. The testing identified non-intuitive transient responses arising from the large thermal capacitance of the stack that are inherent to hybrid systems. Furthermore, the tests demonstrated the capabilities of HILS as a research tool for investigating the dynamic behavior of SOFC/GT hybrid power generation systems.
157

Phenotypic and genotypic characterization of white maize inbreds, hybrids and synthetics under stress and non-stress environments

Makumbi, Dan 30 October 2006 (has links)
Maize is susceptible to biotic and abiotic stresses. The most important abiotic stresses in Africa are drought and low soil fertility. Aflatoxin contamination is a potential problem in areas facing drought and low soil fertility. Three studies were conducted to evaluate maize germplasm for tolerance to stress. In the first study, fifteen maize inbred lines crossed in a diallel were evaluated under drought, low N stress, and well-watered conditions at six locations in three countries to estimate general (GCA) and specific combining ability (SCA), investigate genotype x environment interaction, and estimate genetic diversity and its relationship with grain yield and heterosis. GCA effects were not significant for grain yield across environments. Lines with good GCA effect for grain yield were P501 and CML258 across stresses. Lines CML339, CML341, and SPLC7-F had good GCA effects for anthesis silking interval across stresses. Additive genetic effects were more important for grain yield under drought and well-watered conditions. Heterosis estimates were highest in stress environments. Clustering based on genetic distance calculated using marker data from AFLP, RFLP, and SSRs grouped lines according to origin. Genetic distance was positively correlated with grain yield and specific combining ability. In the second study, synthetic hybrids were evaluated at seven locations in three countries to estimate GCA and SCA effects under low N stress and optimal conditions and investigate genotype x environment interaction. GCA effects were significant for all traits across low N stress and optimal conditions. The highest yielding synthetic hybrids involved synthetics developed from stress tolerant lines. Synthetics 99SADVIA-# and SYNA00F2 had good GCA for grain yield across low N stress conditions. Heterosis was highly correlated with grain yield. Optimal environments explained more variation than stress environments. The third study evaluated the agronomic performance and aflatoxin accumulation of single and three-way cross white maize hybrids at five locations in Texas. Inbreds CML343, Tx601W, and Tx110 showed positive GCA effects for grain yield. Significant GCA effects for reduced aflatoxin concentration were observed in lines CML269, CML270, and CML78 across locations. Differences in performance between single and three-way crosses hybrids were dependent mostly on the inbred lines.
158

Synthese und biologische Evaluierung neuartiger Acronycin-Duocarmycin-Hybride / Synthesis and Biological Evaluation of Novel Acronycine-Duocarmycin Hybrid

Heins, Arne 15 December 2011 (has links)
No description available.
159

Kalbotyros terminai Vinco Urbučio "Žodžių darybos teorijoje" / Linguistic terms in Vincas Urbutis "Word-building theory"

Jankevičiūtė, Rasa 19 June 2006 (has links)
Linguistic terms and all use cases were collected from Vincas Urbutis book “Word-building theory”. It was found 1464 different linguistic terms, which were used 4143 times. It was established, that almost 13 of all linguistic terms are descended from Lithuanian (373 terms or 25,5 % of all linguistic terms), 16 other language (216 terms or 14,8 % of all linguistic terms) and 23 of all linguistic terms are hybrids (875 or 59,8 % of all linguistic terms). For the most part of other language one-word terms are descended from classical – the Latin (104 terms or 40 % of all one-word terms) and the Greek (52 terms or 20 % of all one-word terms) – languages. It was found 13 terms or 5 % of all one-word terms, which are descended from the French language and 7 terms descended from other languages. 302 compound terms are Lithuanian (25,1 % of all compound terms). It was found 40 international compound terms (3,3 % of all compound terms). The biggest part of compound terms forms hybrids (71,6 % of all compound terms). From the respect of structure, terms are different – one-word (260 terms or 17,8 % of all terms) and compound (1204 terms or 82,2 % of all terms). The biggest part of one-word terms forms derivatives (150 terms or 57,7 % of all one-word terms), other part (110 terms or 42,3 % of all one-word terms) forms primary terms. The biggest part of linguistic terms are built with suffixes (114 terms or 43,8 % of all one-word terms). Mostly derivatives of suffixes are action names (4... [to full text]
160

Genetic characteristics of diversity of apple resistance to apple scab / Obels atsparumo rauplėgrybiui įvairovės genetinė charakteristika

Sikorskaitė-Gudžiūnienė, Sidona 08 December 2014 (has links)
The aim of the research. To identify genes involved in V. inaequalis induced resistance response in Malus sp. and to develop apple hybrids with pyramidic resistance. Specific aims: 1. To characterize the genetic diversity and resistance to apple scab in the collection of apple genetic resources; 2. To develop apple hybrids of pyramidic resistance for apple breeding; 3. To characterize apple nuclear proteome and to perform a comparative genomic analysis of V. inaequalis induced Malus response; 4. To identify apple resistance genes involved in response to apple scab and to develop functional markers. / Tyrimų tikslas: identifikuoti V. inaequalis indukuojamo Malus sp. apsauginio atsako reikšmingus genus ir sukurti piramidinio atsparumo rauplėgrybiui donorus obels selekcijai. Tyrimų uždaviniai: 1. Charakterizuoti obels genetinių išteklių įvairovę bei nustatyti jų atsparumą rauplėgrybiui; 2. Sukurti ir atrinkti superjautrumo atsaku pagrįsto piramidinio atsparumo donorus obels selekcijai; 3. Charakterizuoti naminės obels ląstelės branduolio proteomą ir atlikti V. inaequalis indukuojamo atsako lyginamosios genomikos analizę; 4. Identifikuoti obels atsparumo rauplėgrybiui reikšmingus genus ir sukurti obels atsparumo ligoms funkcinius žymeklius.

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