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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.
11

Quantification of Low-Level Cyanobacteria Using A Microflow Cytometry Platform for Early Warning of Potential Cyanobacterial Blooms / A Microflow Cytometry Based Platform For Biosensing

Zhang, Yushan January 2021 (has links)
Cyanobacteria, also known as blue-green algae for a long time, are the most ancient and problematic bloom-forming phylum on earth. An alert levels framework has been established by World Health Organization(WHO) to prevent the potential harmful cyanobacterial blooms. Normally, low cyanobacteria levels are found in surface water. 2000 cyanobacterial cells/mL and 100,000 cyanobacterial cells/mL are established for WHO Alert Level 1 and 2, respectively. However, eutrophication, climate change and other factors may promote the spread of cyanobacteria and increase the occurrence of harmful cyanobacterial blooms in water on a global scale. Hence, a rapid real time cyanobacteiral monitoring system is required to protect public health from the cyanotoxins produced by toxic cyanobacterial species. Current methods to control or prevent the development of harmful cyanobacterial blooms are either expensive, time consuming or not effective in the long term. The best method to control the blooms is to prevent the formation of the blooms at the very beginning. Although emerging advanced autofluorescence-based sensors, imaging flow cytometry applications, and remote sensing have been utilized for rapid real-time enumeration and classification of cyanobacteria, the need to accurately monitor low-level cyanobacterial species in water remains unsolved. Microflow cytometry has been employed as a functional cell analysis technique in past decades, and it can provide real-time, accurate results. The autofluorescence of cyanobacterial pigments can be used for determination and counting of cyanobacterial density in water. A pre-concentration system of an automated cyanobacterial concentration and recovery system (ACCRS) based on tangential flow filtration and back-flushing technique was applied to reduce the sample assay volume and increase the concentration of target cells for further cell capture and detection. In this project, a microflow cytometry platform with a microfluidic device and an automated pre-concentration system was established to monitor cyanobacteria and provide early warning alerts for potential harmful blooms. In this work, quantification of low-level cyanobacterial samples (∼ 5 cyanobacterial cells/mL) in water has been achieved by using a microflow cytometer together with a pre-concentration system (ACCRS). Meanwhile, this platform can also provide early warning alerts for potential harmful cyanobacterial blooms at least 15 days earlier before reaching WHO Alert Level 1. Results have shown that this platform can be applied for rapid determination of cyanobacteria and early warning alerts can be triggered for authorities to protect the public and the environment. / Thesis / Doctor of Engineering (DEng) / Harmful cyanobacterial blooms have been a rising risk to the public heath across the world in recent decades. Alert levels of cyanobacteria in water has also been established. In this case, a rapid on-side monitoring system for cyanobacteria is required. In this thesis, a microflow cytometer platform combined with a bacterial concentration and recovery system was built to quickly monitor the relatively low level of cyanobacteria for early warning alerts. A pre-enrichment system based on tangential flow filtration and back-flushing technique was applied to increase the concentration levels of microbial samples and a microfluidic device capable of collecting phycocyanin fluorescence was designed to count cyanobacterial cells. The limit of quantification for cyanobacterial concentration based on the microflow cytometry platform was as low as ∼ 5 cells/mL. We can claim that the microflow cytometry platform can provide useful early warning alerts for the decision-makers to control the potential harmful cyanobacterial blooms at the very early stage and protect the aquatic animals and public health.
12

The Modulatory Role of Circulating Microvesicles in Endothelial Progenitor Cell Function Is Altered in T2DM.

Ammar, Hala Mustafa 30 May 2014 (has links)
No description available.
13

Uso de microalgas com potencial para produção de biodiesel e mitigação de impactos ambientais

Sassi , Patrícia Giulianna Petraglia 29 April 2016 (has links)
Submitted by Cristhiane Guerra (cristhiane.guerra@gmail.com) on 2017-01-26T13:46:12Z No. of bitstreams: 1 arquivototal.pdf: 2351125 bytes, checksum: 8c803897c206bd195b74d9a1414c0a1a (MD5) / Made available in DSpace on 2017-01-26T13:46:12Z (GMT). No. of bitstreams: 1 arquivototal.pdf: 2351125 bytes, checksum: 8c803897c206bd195b74d9a1414c0a1a (MD5) Previous issue date: 2016-04-29 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / Microalgae have been the focus of great interest for the biofuels production due to its enormous capacity to produce biomass, and because many species produce fatty acids in amounts many times the various oleaginous plants. Many microalgae also act as efficient bioremediators domestic and industrial residues, so integrated cultivation of promising microalgae for biofuels coupled to wastewater treatment systems can provide several benefits including cost reductions in effluents treatment and biomass microalgal production, cheapening the culture, promoting nutrient removal and minimizing environmental impacts. This research aimed to evaluate the effectiveness of regional microalgae act in the bioremediation of three types of effluents: biodiesel washing water, shrimp wastewater and agricultural drainage water using potentially promising species for the production of biodiesel that can grow in these effluents as a culture medium . Were used 12 isolated species of microalgae various aquatic environments in northeastern Brazil with 11 freshwater and 1 marine. The selection of species was made considering those which produce substantial amounts of fatty acids, with some even superior to soy. The experiments were performed in chambre culture (25 ± 1 ° C, photoperiod of 12h) in balloons 6L capacity with continuous aeration. The growth of the species under the conditions tested was accompanied by cell counts and measurement of fluorescence in vivo and the physiological responses by flow cytometry. In the effluent were determined NO3, NO2, PO4, pH, COD, turbidity, electrical conductivity and total solids using analytical procedures and/or multiparameter probe. In biodiesel washing water 11 species were tested, only two of which showed good growth. Of these, Monoraphidium contortum was selected for the bioremediation tests due to its higher capacity for growth and be the second species with a higher content of fatty acids. It was found that the species reduces the concentration of NO3, PO4, and COD in percentages of 25.8%, 7.2% and 31.2%, respectively. In shrimp farming water the genus Amphora sp. it showed considerable growth, but lower than the control, but with higher production lipids. Removal PO4, NO3 and NO2 in this species in this effluent was 73.357%, 72.572% and 66.667%, respectively. In agricultural drainage water were tested of which 11 species. Monoraphidium contortum was selected for the bioremediation test and biomass production and yield of the final number of cells in this experimental condition were lower than the control. In this kind effluent removed approximately 73% and 100% for respectively NO3 and PO4. Comparisons of physiological responses showed cell concentrations, florescence chlorophyll and activity of higher esterase in control and increased production of lipids in the drainage water The data show it is possible to use these effluents in the cultivation of microalgae important for biodiesel production with effective reduction of nutrients present in wastewater and that, depending on the species, the effluent may offer favorable conditions for increased production of lipids. However, microalgal cultures in these effluents can be double interest: to minimize environmental impact and producing microalgal biomass that can be used to produce biodiesel, or other byproducts of interest to the biotechnology, thereby reducing production costs in mass culture. / As microalgas têm sido foco de grande interesse para a produção de biocombustíveis devido a sua enorme capacidade de produzir biomassa, e pelo fato de muitas espécies produzirem ácidos graxos em quantidades muitas vezes superiores à várias oleaginosas. Muitas microalgas também atuam como eficientes biorremediadores de resíduos domésticos e agroindustriais, de maneira que sistemas integrados de cultivo de microalgas promissoras para a produção de biocombustíveis acoplados ao tratamento de efluentes podem apresentar vários benefícios incluindo redução de custos no tratamento de águas residuais e produção de biomassa microalgal, barateando os cultivos, promovendo remoção de nutrientes e minimizando impactos ambientais. Esta pesquisa visou avaliar a efetividade de microalgas regionais atuarem na biorremediação de três tipos de efluentes: água de lavagem de biodiesel, efluente de carcinicultura e água de drenagem agrícola, utilizando espécies potencialmente promissoras à produção de biodiesel que podem crescer nesses efluentes como meio de cultura. Foram utilizadas 12 espécies de microalgas isoladas de vários ambientes aquáticos do Nordeste do Brasil sendo 11 dulcícolas e uma marinha. A seleção das espécies foi feita considerando-se aquelas que produzem substanciais quantidades de ácidos graxos, com algumas inclusive superiores à soja. Os experimentos foram realizados em câmara de cultura climatizada (25 ± 1 ºC, fotoperíodo de 12h) em balões de 6L de capacidade com aeração contínua. O crescimento das espécies nas condições testadas foi acompanhado por contagens celular e medidas da fluorescência in vivo e as respostas fisiológicas por citometria de fluxo. Nos efluentes foram determinados os teores de NO3, NO2, PO4, pH, DQO, turbidez, condutividade elétrica e sólidos totais usando procedimentos analíticos e/ou sonda multiparâmetros. Em água de lavagem de biodiesel foram testadas 11 espécies, das quais apenas duas apresentaram bom crescimento. Destas, Monoraphidium contortum foi selecionada para os testes de biorremediação por apresentar maior capacidade de crescimento e ser a segunda espécie com maior teor de ácidos graxos. Constatou-se que esta espécie reduz as concentrações de NO3, PO4, e DQO nas porcentagens de 25,8%, 7,2% e 31,2%, respectivamente. Em água de carcinicultura o gênero Amphora sp. mostrou crescimento considerável, porém inferior ao controle com produção de lipídeos superior. A remoção de PO4, NO3 e NO2 por esta espécie nesse efluente foi de 73,357%, 72,572% e 66,667%, respectivamente. Em água de drenagem agrícola foram testadas 11 espécies das quais M. contortum foi selecionada para o ensaio de biorremediação e sua produção de biomassa e o rendimento final em número de células nesta condição experimental foram inferiores ao controle. Neste efluente essa espécie removeu aproximadamente 73% de NO3 e 100% de PO4. As comparações das respostas fisiológicas demonstraram concentrações celulares, florescência da clorofila e atividade da esterase mais elevadas no controle e maior produção de lipídeos no efluente. Os dados mostram ser possível a utilização desses efluentes no cultivo de microalgas importantes à produção de biodiesel com reduções efetivas dos nutrientes presentes na água residual e que, dependendo da espécie, os efluentes podem oferecer condições favoráveis a uma maior produção de lipídeos. Contudo, os cultivos de microalgas nesses efluentes podem ter duplo interesse: minimizar impactos ambientais e produzir biomassa microalgal que pode ser usada para produção de biodiesel ou outros coprodutos de interesse à biotecnologia, reduzindo assim os custos de produção em cultivos em massa.
14

Determinação da porcentagem de espermatozóides portadores de cromossomos X e Y no sêmen sexado mediante PCR em tempo real / Determination of the proportion of X- and Y- bearing spermatozoa in bovine sexed semen by real time PCR

Sverzut, Viviane Guidi 01 September 2011 (has links)
A produção animal atualmente conta com diferentes biotecnologias para aumentar sua produtividade, incluindo técnicas aplicadas na reprodução. A inseminação artificial, por exemplo, vem sendo aplicada há muitos anos e de maneira extensiva. Esta tem como objetivo o aproveitamento de apenas um ejaculado em diversas prenhezes viabilizando a realização de testes de progênies e um grande aproveitamento de touros melhoradores. Atualmente essa técnica pode contar com um material ainda mais específico, o sêmen sexado que possui maior porcentagem (acima de 87%) de espermatozóides portadores de cromossomo X ou Y resultando numa progênie com o sexo predeterminado. A pré-seleção do sexo vem sendo estudada desde final dos anos 70, uma das linhas de pesquisa resultaram no desenvolvimento de um equipamento, o citômetro de fluxo, em que a célula espermática tem seu conteúdo de DNA estimado e, na seqüência é orientado para separação. Atualmente essa técnica é utilizada para produção de sêmen sexado comercialmente, anteriormente à comercialização do produto, a confirmação da taxa de separação dos cromossomos X e Y é realizada pelo próprio equipamento, o que acrescenta um custo operacional e pode introduzir um viés na confirmação da taxa de sexagem. Sendo assim o objetivo desse trabalho foi elaborar um protocolo de confirmação da taxa de sexagem mediante PCR em tempo real, utilizando sonda TaqMan® em regiões dos genes X-específico (PLP) e Y-específico (SRY). Foram analisadas duas sub-espécies de bovinos (Bos primigenius taurus e Bos primigenius indicus), sendo 21 doses de sêmen sexado X, 21 doses de sêmen sexado Y e 42 doses de sêmen não sexado (controle). A extração do DNA foi desenvolvida com a utilização de di-etiltreitol (DTT) e isotiocianato de guanidina. As amostras foram, em seguida, submetidas à técnica de PCR em tempo real aplicando sondas específicas. Foi possível amplificar os fragmentos específicos dos cromossomos X e Y separadamente e em conjunto e estimar a proporção relativa entre ambos. Todavia a repetibilidade do teste e sua acurácia não permitem recomendá-lo da maneira que se encontra para a aplicação na prática. / There are different biotechnologies to apply to increase the animal production nowadays, reproduction techniques are including. The artificial insemination (AI), for example, is a technique very used during many years ago and it is used at extensive production. The aim of this technique is to increase the numbers of pregnancies with just one ejaculation what will propose easier testing of offspring and better use of genetic selected bulls. At present the AI can associate a more specific material, the sexed semen, that contains a higher percentage (more than 87%) of X- or Y- bearing spermatozoa. Its application will result in a offspring with the desired sex. The sorting sex process has been studied since the 1970\'s, since then, some researchers have determined the cytometric sexing flow, a \"promising technique\" that allows the separation of the X-bearing chromosome sperm from the Y-bearing chromosome sperm based on the estimation of the DNA content in each measured cell. The cytometric flow is the unique commercial technique applied for mammalian species in many countries. Before the commercialization the bovine sexed semen has its percentage of the desired sex confirmed by using the same technique that sorted at the beginning of the process. This point can improve the cost and benefits the sorting technique. This way, the objective of this study was to determine a protocol of sex proportion confirmation by real time PCR using TaqMan® probe at X-specific gene (PLP) and Y-specific gene (SRY). Two subspecies of cattle semen were analyzed (Bos primigenius taurus and Bos primigenius indicus). Twenty-one sexed semen for female, other twenty-one sexed semen for male and forty-two non sexed semen were used in this research. The DNA extraction used DTT and guanidine isothiocyanate, and then the obtained samples were used to the real time PCR applying specific probes. This study allows the amplification in different reactions of specific products of X-chromosome bearing and Y-chromosome bearing. Putting the results together, it was possible to determine the relative proportion between the products. But the repeatability and accuracy of the test don\'t permit use this technique in this way of practice.
15

Determinação da porcentagem de espermatozóides portadores de cromossomos X e Y no sêmen sexado mediante PCR em tempo real / Determination of the proportion of X- and Y- bearing spermatozoa in bovine sexed semen by real time PCR

Viviane Guidi Sverzut 01 September 2011 (has links)
A produção animal atualmente conta com diferentes biotecnologias para aumentar sua produtividade, incluindo técnicas aplicadas na reprodução. A inseminação artificial, por exemplo, vem sendo aplicada há muitos anos e de maneira extensiva. Esta tem como objetivo o aproveitamento de apenas um ejaculado em diversas prenhezes viabilizando a realização de testes de progênies e um grande aproveitamento de touros melhoradores. Atualmente essa técnica pode contar com um material ainda mais específico, o sêmen sexado que possui maior porcentagem (acima de 87%) de espermatozóides portadores de cromossomo X ou Y resultando numa progênie com o sexo predeterminado. A pré-seleção do sexo vem sendo estudada desde final dos anos 70, uma das linhas de pesquisa resultaram no desenvolvimento de um equipamento, o citômetro de fluxo, em que a célula espermática tem seu conteúdo de DNA estimado e, na seqüência é orientado para separação. Atualmente essa técnica é utilizada para produção de sêmen sexado comercialmente, anteriormente à comercialização do produto, a confirmação da taxa de separação dos cromossomos X e Y é realizada pelo próprio equipamento, o que acrescenta um custo operacional e pode introduzir um viés na confirmação da taxa de sexagem. Sendo assim o objetivo desse trabalho foi elaborar um protocolo de confirmação da taxa de sexagem mediante PCR em tempo real, utilizando sonda TaqMan® em regiões dos genes X-específico (PLP) e Y-específico (SRY). Foram analisadas duas sub-espécies de bovinos (Bos primigenius taurus e Bos primigenius indicus), sendo 21 doses de sêmen sexado X, 21 doses de sêmen sexado Y e 42 doses de sêmen não sexado (controle). A extração do DNA foi desenvolvida com a utilização de di-etiltreitol (DTT) e isotiocianato de guanidina. As amostras foram, em seguida, submetidas à técnica de PCR em tempo real aplicando sondas específicas. Foi possível amplificar os fragmentos específicos dos cromossomos X e Y separadamente e em conjunto e estimar a proporção relativa entre ambos. Todavia a repetibilidade do teste e sua acurácia não permitem recomendá-lo da maneira que se encontra para a aplicação na prática. / There are different biotechnologies to apply to increase the animal production nowadays, reproduction techniques are including. The artificial insemination (AI), for example, is a technique very used during many years ago and it is used at extensive production. The aim of this technique is to increase the numbers of pregnancies with just one ejaculation what will propose easier testing of offspring and better use of genetic selected bulls. At present the AI can associate a more specific material, the sexed semen, that contains a higher percentage (more than 87%) of X- or Y- bearing spermatozoa. Its application will result in a offspring with the desired sex. The sorting sex process has been studied since the 1970\'s, since then, some researchers have determined the cytometric sexing flow, a \"promising technique\" that allows the separation of the X-bearing chromosome sperm from the Y-bearing chromosome sperm based on the estimation of the DNA content in each measured cell. The cytometric flow is the unique commercial technique applied for mammalian species in many countries. Before the commercialization the bovine sexed semen has its percentage of the desired sex confirmed by using the same technique that sorted at the beginning of the process. This point can improve the cost and benefits the sorting technique. This way, the objective of this study was to determine a protocol of sex proportion confirmation by real time PCR using TaqMan® probe at X-specific gene (PLP) and Y-specific gene (SRY). Two subspecies of cattle semen were analyzed (Bos primigenius taurus and Bos primigenius indicus). Twenty-one sexed semen for female, other twenty-one sexed semen for male and forty-two non sexed semen were used in this research. The DNA extraction used DTT and guanidine isothiocyanate, and then the obtained samples were used to the real time PCR applying specific probes. This study allows the amplification in different reactions of specific products of X-chromosome bearing and Y-chromosome bearing. Putting the results together, it was possible to determine the relative proportion between the products. But the repeatability and accuracy of the test don\'t permit use this technique in this way of practice.
16

Entwicklung und Optimierung eines Cytometric Bead Arrays zum Nachweis von afrikanischen hämorrhagischen Fieberviren / Developement and optimization of a cytometric bead array for the detection of african hemorrhagic fever viruses

Nordmann, Tamara 24 April 2012 (has links)
No description available.
17

A microflow cytometer with simultaneous dielectrophoretic actuation for the optical assay and capacitive cytometry of individual fluid suspended bioparticles

Romanuik, Sean 14 September 2009 (has links)
Fluid suspended biological particles (bioparticles) flowing through a non-uniform electric field are actuated by the induced dielectrophoretic (DEP) force, known to be dependent upon the bioparticles’ dielectric phenotypes. In this work: a 10-1000 kHz DEP actuation potential applied to a co-planar microelectrode array (MEA) induces a DEP force, altering passing bioparticle trajectories as monitored using: (1) an optical assay, in which the lateral bioparticle velocities are estimated from digital video; and (2) a capacitive cytometer, in which a 1.478 GHz capacitance sensor measures the MEA capacitance perturbations induced by passing bioparticles, which is sensitive to the bioparticles’ elevations. The experimentally observed and simulated lateral velocity profiles of actuated polystyrene microspheres (PSS) and viable and heat shocked Saccharomyces cerevisiae cells verify that the bioparticles’ dielectric phenotypes can be inferred from the resultant trajectories due to the balance between the DEP force and the viscous fluid drag force.
18

A microflow cytometer with simultaneous dielectrophoretic actuation for the optical assay and capacitive cytometry of individual fluid suspended bioparticles

Romanuik, Sean 14 September 2009 (has links)
Fluid suspended biological particles (bioparticles) flowing through a non-uniform electric field are actuated by the induced dielectrophoretic (DEP) force, known to be dependent upon the bioparticles’ dielectric phenotypes. In this work: a 10-1000 kHz DEP actuation potential applied to a co-planar microelectrode array (MEA) induces a DEP force, altering passing bioparticle trajectories as monitored using: (1) an optical assay, in which the lateral bioparticle velocities are estimated from digital video; and (2) a capacitive cytometer, in which a 1.478 GHz capacitance sensor measures the MEA capacitance perturbations induced by passing bioparticles, which is sensitive to the bioparticles’ elevations. The experimentally observed and simulated lateral velocity profiles of actuated polystyrene microspheres (PSS) and viable and heat shocked Saccharomyces cerevisiae cells verify that the bioparticles’ dielectric phenotypes can be inferred from the resultant trajectories due to the balance between the DEP force and the viscous fluid drag force.
19

A scientific investigation of the immunomodulatory properties of an indigenous plant, Sutherlandia frutescens

Gonyela, Odwa 01 1900 (has links)
Traditional medicines prepared from Sutherlandia frutescens are used to manage diseases including HIV and cancer. This study aimed at isolating and identifying biologically active compounds isolated from S. frutescens. Sutherlandia frutescens plants were collected in Petrusburg and Paarl. Powdered plant material was extracted using ethanol or water and their metabolite composition was compared using UPLC-MS. A novel cycloartane, an acetylated variant of this compound as well as a Sutherlandioside B triterpenoid was isolated and characterised using chromatographic and analytical techniques such as NMR and UPLC-MS. Preliminary biological studies were conducted to assess the activity of plant extracts on cell toxicity, herpes virus replication and cytokine expression. The results of this study suggest that aqueous extracts from S. frutescens do not appear to be cytotoxic or show anti-herpetic activity, but may activate the immune system by increasing expression of IL-6, IL-10 and TNFα. Further research should be conducted to confirm and optimise these results. / Life and Consumer Sciences / M. Sc. (Life Science)

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