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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.
1

Greenalgae as a substrate for biogas production - cultivation and biogas potentials

Liu, Yang January 2010 (has links)
<p>Algae is regarded as a good potential substrate for biogas production, due to high cells productivity, low cellulose and zero lignin content. Two parts were included in this study: first, cultivations of micro-algae (<em>Chlorella sorokiniana</em> and <em>Tetraselmis suecica</em>) at two different nitrate concentrations, also the effect of addition of CO<sub>2</sub> on algae grow was investigated in this first part. Second, batch fermentations of the cultivated micro-algae as well as a powder <em>Chlorella</em> (obtained from Raw Food Shop) and a dry mix filamentous algae (collected in the pounds in the park at the back of the Tema-building and then dried) were performed. In this part also effects of thermo-lime pretreatment (room temperature, 80<sup>o</sup>C, 105<sup>o</sup>C and 120<sup>o</sup>C) on the algae biogas potentials was investigated.</p><p> </p><p>Both strains of micro-algae cultured at low nitrate gave more CH<sub>4</sub> yield: 319 (±26) mL and 258 (±12) mL CH<sub>4 </sub>per added gVS was obtained during the degradation of <em>Chlorella sorokiniana </em>grown at 0.4mM-N and 2mM-N level, respectively. For<em> Tetraselmis suecica</em> 337 (±37) mL and 236 (±20) mL CH<sub>4</sub> per added gVS was obtained at 2.4mM-N and 12mM-N level, respectively. Powder <em>Chlorella</em> gave the highest biogas production (719 ±53 mL/added gVS) and CH<sub>4</sub> yields (392 ±14 mL/added gVS), followed by the dry filamentou<em>s</em> algae (661 ±20 mL biogas and 295 ±9 mL CH<sub>4</sub> per added gVS) and <em>Tetraselmis suecica</em> (12 mM-N; 584 ±7 mL biogas and 295 ±9 mL CH<sub>4</sub> per added gVS).</p><p> </p><p>A negative effect of lime treatment at room temperature on CH<sub>4</sub> yield of algal biomass was obtained. Lime treatment at 120<sup>o</sup>C showed the fastest degradation rate for <em>Tetraselmis</em> <em>suecica </em>and powder <em>Chlorella</em> during the initial 5 days of incubation.  </p><p> </p><p><em>Chlorella sorokiniana</em> and <em>Tetraselmis suecica</em> cultures flushed with biogas containing 70% and also CO<sub>2</sub> enriched air (5% CO<sub>2</sub>) did not increase cells growth (measured as OD<sub>600</sub>) if compared to references grown under air. On the contrary, a clearly inhibition effect on the algal cells growth was observed in some cultures.</p>
2

Greenalgae as a substrate for biogas production - cultivation and biogas potentials

Liu, Yang January 2010 (has links)
Algae is regarded as a good potential substrate for biogas production, due to high cells productivity, low cellulose and zero lignin content. Two parts were included in this study: first, cultivations of micro-algae (Chlorella sorokiniana and Tetraselmis suecica) at two different nitrate concentrations, also the effect of addition of CO2 on algae grow was investigated in this first part. Second, batch fermentations of the cultivated micro-algae as well as a powder Chlorella (obtained from Raw Food Shop) and a dry mix filamentous algae (collected in the pounds in the park at the back of the Tema-building and then dried) were performed. In this part also effects of thermo-lime pretreatment (room temperature, 80oC, 105oC and 120oC) on the algae biogas potentials was investigated. Both strains of micro-algae cultured at low nitrate gave more CH4 yield: 319 (±26) mL and 258 (±12) mL CH4 per added gVS was obtained during the degradation of Chlorella sorokiniana grown at 0.4mM-N and 2mM-N level, respectively. For Tetraselmis suecica 337 (±37) mL and 236 (±20) mL CH4 per added gVS was obtained at 2.4mM-N and 12mM-N level, respectively. Powder Chlorella gave the highest biogas production (719 ±53 mL/added gVS) and CH4 yields (392 ±14 mL/added gVS), followed by the dry filamentous algae (661 ±20 mL biogas and 295 ±9 mL CH4 per added gVS) and Tetraselmis suecica (12 mM-N; 584 ±7 mL biogas and 295 ±9 mL CH4 per added gVS). A negative effect of lime treatment at room temperature on CH4 yield of algal biomass was obtained. Lime treatment at 120oC showed the fastest degradation rate for Tetraselmis suecica and powder Chlorella during the initial 5 days of incubation. Chlorella sorokiniana and Tetraselmis suecica cultures flushed with biogas containing 70% and also CO2 enriched air (5% CO2) did not increase cells growth (measured as OD600) if compared to references grown under air. On the contrary, a clearly inhibition effect on the algal cells growth was observed in some cultures.
3

Process development for the control of solubility of Affibody® molecules

Dolfe, Lisa January 2011 (has links)
In this study the aim was to optimize the production of the Affibody fusion-protein Z03358- ABD094-(S4G)3-IL2 with regard to the amount of soluble protein produced. However, problems with reproducibility with this protein and the chosen expression system were encountered. Therefore, expression of the His-tagged Affibody His6-(Z05477)2 was evaluated using the same expression system as well as expression in another well characterized expression system. Both target proteins are of therapeutic interest. One of the proteins is an IL2 fusion protein (Z03358-ABD094-(S4G)3-IL2) that bind the platelet-derived growth factor receptor β (PDGFR-β). PDGF signaling is of interest in cancer treatment where, among other things, the effects of PDGF on tumor angiogenesis is researched. The His6-(Z05477)2 protein has a classified target but is developed as a therapeutic in the area of inflammation and autoimmune disease. Both model proteins are known to be difficult to purify due to low solubility. The two E. coli expression systems investigated and compared were BL21(DE3) and Lemo21(DE3). The fusion protein Z03358-ABD094-(S4G)3-IL2 was produced in BL21(DE3) in inclusion bodies with a yield of 4.95 g/l. An optimized process for the expression of His6-(Z05477)2 using BL21(DE3) was developed with a yield of 6.6 g/l soluble protein after expression at 30°C for 6 h.
4

Estudo do metabolismo de Salmonella typhimurium : da abordagem tradicional à análise dos fluxos metabólicos

Sargo, Cíntia Regina 27 August 2015 (has links)
Submitted by Alison Vanceto (alison-vanceto@hotmail.com) on 2017-01-23T10:29:06Z No. of bitstreams: 1 TeseCRS.pdf: 3506039 bytes, checksum: 68f4c5fe1c6ae3672adcedf3450e2f31 (MD5) / Approved for entry into archive by Camila Passos (camilapassos@ufscar.br) on 2017-01-23T15:48:35Z (GMT) No. of bitstreams: 1 TeseCRS.pdf: 3506039 bytes, checksum: 68f4c5fe1c6ae3672adcedf3450e2f31 (MD5) / Approved for entry into archive by Camila Passos (camilapassos@ufscar.br) on 2017-01-23T15:48:42Z (GMT) No. of bitstreams: 1 TeseCRS.pdf: 3506039 bytes, checksum: 68f4c5fe1c6ae3672adcedf3450e2f31 (MD5) / Made available in DSpace on 2017-01-23T15:48:50Z (GMT). No. of bitstreams: 1 TeseCRS.pdf: 3506039 bytes, checksum: 68f4c5fe1c6ae3672adcedf3450e2f31 (MD5) Previous issue date: 2015-08-27 / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / The genus Salmonella spp. has been extensively investigated because these bacteria are important pathogens that frequently cause severe diseases and gastrointestinal infections in humans and animals. Moreover, in recent years, Salmonella has called attention due to the excellent results in the production and in vivo delivery of various substances with potential application in Vaccinology. However, there is still little information available concerning aspects of its metabolism, which hampers both the development of new attenuated strains and the large-scale production of live cells and cellular components. Thus, this work aimed to study the S. typhimurium LT2 metabolism, using traditional and innovative approaches to investigate different carbon sources as well as different bioreactor operation modes and aeration conditions (aerobic and anaerobic). Results obtained in batch and chemostat cultivations indicated that S. typhimurium metabolism differs significantly from E. coli metabolism, closely related bacteria species with regard to the central carbon metabolism. The main difference observed between these bacteria was the high level of acetate production exhibited by S. typhimurium LT2 cells, which, differently from E. coli, occurred even at the lowest dilution rate evaluated. Currently, genome scale metabolic models are important tools for better understanding the phenotypic behavior of many organisms. Therefore the model STM_v1.0 reconstructed for S. typhimurium LT2 was evaluated, comparing experimental data, obtained in chemostat cultivations, with model predictions. Since this model was derived from E. coli model, the simulated results for biomass formation were overestimated and, consequently, predicted acetate fluxes were lower than those obtained experimentally. Therefore, to obtain experimental data useful to improve the model and to reach a better comprehension of S. typhimurium metabolism, the technique of metabolic flux analysis using isotopic labeled substrate was adopted, allowing determination of the fluxes for the main pathways of central carbon metabolism of Salmonella. This analysis revealed different preferred metabolic pathways depending on the specific growth rate. At the lowest dilution rate evaluated, D = 0.24 h-1, glucose was catabolized predominantly by the pentose phosphate and glycolysis pathways, while at the dilution rate of 0.48 h-1, the major pathway of glucose oxidation was Entner-Doudoroff. In addition, a relatively high flux through the citric acid cycle at the higher dilution rate studied was observed. / Bactérias do gênero Salmonella spp. são extensivamente estudadas por serem importantes patógenos, causando frequentemente graves doenças e infecções gastrointestinais em humanos e animais. Além disso, nos últimos anos, estas bactérias vêm ganhando um destaque ainda maior na área da biotecnologia por apresentarem ótimos resultados na produção e veiculação in vivo de diversas substâncias com fins vacinais. No entanto, ainda há poucas informações a respeito de seu metabolismo, dificultando tanto o desenvolvimento de novas linhagens atenuadas, como também a produção em larga escala de células vivas e de componentes celulares. Neste sentido, este trabalho se propôs a estudar o metabolismo de S. typhimurium LT2, utilizando inicialmente abordagens tradicionais para investigar seu comportamento na presença de diferentes fontes de carbono, em diferentes modos de operação de biorreator e de aeração (aeróbias e anaeróbias). Os resultados obtidos em cultivos em batelada e em quimiostatos evidenciaram que o metabolismo da S. typhimurium difere bastante do metabolismo da E. coli, espécies consideradas semelhantes com relação ao metabolismo do carbono central. A principal diferença observada entre essas duas bactérias foi a elevada produção de acetato pelas células de S. typhimurium LT2, mesmo em baixas velocidades de crescimento nas quais este metabólito não é produzido por diversas estirpes de E. coli. Atualmente, modelos metabólicos em escala genômica são ferramentas importantes para que o comportamento do fenótipo de diversos organismos sejam melhor compreendidos. Assim, avaliou-se o modelo STM_v1.0 reconstruído para S. typhimurium LT2, comparando-se dados obtidos experimentalmente, em quimiostatos, e os preditos pelo modelo. No entanto, como este modelo foi baseado no modelo da E. coli, os resultados simulados para produção de biomassa foram superestimados e, consequentemente, os fluxos de acetato foram inferiores aos obtidos experimentalmente. Sendo assim, para se obter dados experimentais úteis para aprimorar o modelo e para uma compreensão maior do metabolismo de S. typhimurium, utilizou-se a técnica de análise dos fluxos metabólicos com substrato isotopicamente marcado, permitindo a determinação dos fluxos das principais vias do metabolismo do carbono central da bactéria em estudo. Essa análise revelou diferenças na utilização das vias metabólicas em função da velocidade específica de crescimento, sendo que na menor taxa de diluição avaliada, D = 0,24 h-1, a glicose foi predominantemente catabolizada pelas vias pentose fosfato e glicólise, enquanto na taxa de diluição de 0,48 h-1, a via principal de oxidação da glicose foi a Entner- Doudoroff. Além disso, também observou-se um fluxo relativamente maior na via do ciclo do ácido cítrico na maior taxa de diluição estudada.
5

Mini-odlingar i urban miljö : En utvärdering av miniträdgårdar/blomurnor i Hemsta, Gävle

Persson, Theodor January 2020 (has links)
Framtiden kommer att sätta städer på prov i och med att världens befolkning och urbanisering ökar. Detta utsätter livsviktiga förutsättningar som ekosystemtjänster och pollinering för stora hot, då en ökande urbanisering gör att grönytor i städer minskar. Samtidigt som att de som finns oftast är av en karaktär som inte är speciellt gynnsam för den biologiska mångfalden. Det har påvisats att det kan finnas ett positivt samband mellan biologisk mångfald och människans välmående. Samtidigt poängterar flertalet studier de hälsofrämjande effekter naturen har på människor, sett till både det fysiska och det mentala. Om rätt förutsättningar ges för städer kan det skapa möjligheter som bidrar med positiva effekter för en hållbar stadsutveckling. Syftet med studien är att undersöka vilka effekter småskalig odling i urban miljö kan ha för att öka biologisk mångfald och ekosystemtjänster i staden, samt boendes relation till naturmiljöer. Studien fokuserade på miniträdgårdar/blomurnor som placerats ut i ett bostadsområde i Gävle, Sverige. Dessa delades ut till hushåll som ville ta hand om dem under 2019. Resultatet av både en enkätundersökning och en litteraturundersökning visar på att miniträdgårdar kan ses som en förbättringsåtgärd/ett verktyg för att främja hållbarheten i städer gällande både de ekologiska och sociala aspekterna. En analys av en inventeringsstudie som skedde mellan år 2018 och 2019 gällande pollinerande insekter för området i Gävle, visade på att förekomsten av pollinatörer hade ökat. Enkätstudien av 39 svaranden visade på att de som tyckte att det skett en förändring i och med tillkomsten av miniträdgårdar/blomurnor, tyckte att det varit i en positiv mening. Det visade sig även att i jämförelse mellan år 2019 och 2020 hade de boendes inställning till olika inslag i naturen ökat i en positiv mening. Detta skulle kunna förklaras som att exponeringen av miniträdgårdar/blomurnor har lett till mer pro-ekologiska attityder. Slutligen konstateras att vidare studier inom ämnet behöver genomföras för att kunna ge ett tydligare svar av vad för slags mini-odlingar som är bäst lämpade och i vilken utsträckning dessa är nödvändiga för att uppnå positiva resultat. / The future will put cities to test as the world's population and urbanization increases. This may lead to threats to vital conditions for ecosystem services and pollination as such. As a result of increasing urbanization, green spaces in cities are declining and those of existence are usually of a character that is not particularly favorable for biodiversity. It has been shown that there can be a positive relationship between biodiversity and human well-being. At the same time, several studies point out the health-beneficial effects that nature has on humans, regarding both physical and mental health. As well as providing right conditions for cities, it can create opportunities that contribute with positive effects for sustainable urban development. The aim of this study is to investigate what effects small-scale cultivation in an urban environment has on biodiversity and ecosystem services in the city, as well as the resident’s relationship to natural environments. The study has focused on arrangements of miniature gardens/flower urns placed in a residential area in Gävle, Sweden. These were distributed to households who wanted to take care of them in 2019. The result of both a questionnaire survey and a literature study show that such an arrangement can be seen as an improvement action/tool to promote sustainability in cities regarding both the ecological and social aspects. An analysis of an inventory study which occurred between the years 2018 and 2019 that looked at pollinators in the resident area in Gävle, showed that the abundance of pollinators had risen. The questionnaire survey of 39 answers showed that of those who felt that a change had occurred with the presence of the miniature gardens/flower urns thought that it had been in a positive way. Compared to 2019, the residents' attitudes towards natural elements had been increasingly positive in 2020. This could be explained by the fact that the presence of the miniature gardens/flower urns has affected their values in a pro-ecological manner. Finally, it is concluded that to give a clearer answer of what kinds of small-scale cultivations that are best suited and to what extent these are necessary to achieve positive results, further studies in the subject are needed.
6

Generative Modelling and Probabilistic Inference of Growth Patterns of Individual Microbes

Nagarajan, Shashi January 2022 (has links)
The fundamental question of how cells maintain their characteristic size remains open. Cell size measurements made through microscopic time-lapse imaging of microfluidic single cell cultivations have posed serious challenges to classical cell growth models and are supporting the development of newer, nuanced models that explain empirical findings better. Yet current models are limited, either to specific types of cells and/or to cell growth under specific microenvironmental conditions. Together with the fact that tools for robust analysis of said time-lapse images are not widely available as yet, the above-mentioned point presents an opportunity to progress the cell growth and size homeostasis discourse through generative, probabilistic modeling and analysis of the utility of different statistical estimation and inference techniques in recovering the parameters of the same. In this thesis, I present a novel Model Framework for simulating microfluidic single-cell cultivations with 36 different simulation modalities, each integrating dominant cell growth theories and generative modelling techniques. I also present a comparative analysis of how different Frequentist and Bayesian probabilistic inference techniques such as Nuisance Variable Elimination and Variational Inference work in the context of a case study of the estimation of a single model describing a microfluidic cell cultivation.

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