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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

Optical studies of diatomic molecules at extreme conditions

Afonina, Veronika Semenovna January 2018 (has links)
The formidable progress achieved in the research at extreme conditions led to important discoveries of many unusual and interesting physical and chemical phenomena. Materials with high compressibility were and still are of particular interest due to a significant reduction of volume which could result in unexpected changes of bonding and/or electronic properties. Among highly compressible materials simple diatomic molecules such as H2, N2, and O2 are particularly interesting because they form new types of solids at high pressure. Hydrogen, being the most abundant element in the universe, possesses simple electronic structure, therefore, the study of hydrogen systems is of special interest. In the last three decades, there were subsequently explored and described several high-pressure phases of hydrogen up to 400 GPa. However, there is still a vast area of unexplained effects, which requires further analysis. The contributed work discusses Raman experiments in a wide pressure and temperature range where rotational and lattice phonon excitations have been measured in the Raman spectrum of solid H2 and D2 at 10, 77, 150 and 300 K from 2 to 180 GPa and up to 380 GPa at 300 K. Analysis of the Raman spectra allows to model how the rotational modes change with pressure and temperature and how the mass scaling laws evolve as the density increases in both hydrogen and deuterium. Comparison of vibrational frequencies of the isotopes appears to be extremely useful for estimation of equivalent pressures for both isotopes. Nitrogen and oxygen are archetypal elements possessing unique features such as extremely strong triple bond in case of N2 and magnetic moment in O2 . Both N2 and O2 exhibit rich polymorphism, with additional phases of O2 derived from its electronic and magnetic properties. N2 /O2 mixtures (for example, 20.9% O2 and 78% N2 mixture is air that we breathe) have been studied up to 12 GPa at 300 K experimentally and explored up to 500 GPa at 0 K theoretically. In the current project, N2 /O2 molecular systems are examined at 300 K up to 150 GPa. Rich polymorphism is observed, with seven phases exhibiting drastically different Raman spectra for concentrations below 45% of O2 and a more stable area with three phases in the concentration range from 45% to 80% of oxygen at pressures above 12 GPa. Moreover, characteristic Raman spectra obtained for the mix with 25% O2 after laser heating to approximately 2000 K at 25 and 96 GPa reveals pronounced peaks indicating the potential formation of new compounds.
2

Atividade lipolítica e biodiversidade de fungos filamentosos derivados da Antártica. / Lipase activity and biodiversity of filamentous fungi derived from Antarctica.

Nobre, Fernando Suzigan 26 March 2013 (has links)
Lipases ativas em temperaturas frias estão amplamente distribuídas em micro-organismos que sobrevivem em temperaturas baixas, neste contexto, o isolamento de fungos de ambiente antártico pode ser considerado estratégico para obtenção de lipases a baixas temperaturas. O presente trabalho teve como objetivo avaliar a produção de lipases e a diversidade de fungos filamentosos isolados de amostras do ambiente Antártico. Um total de 253 isolados foi recuperado a partir de 10 amostras marinhas e quatro terrestres, dos quais 68 apresentaram resultados positivo e foram submetidos aos experimentos de avaliação da produção de lipase e caracterização da biodiversidade. Os fungos lipolíticos foram identificados como pertencentes aos gêneros: Geomyces, Penicillium, Cosmospora, Thelebolus, Chaetomium, Hypocrea, Antarctomyces, Mortierella e Cadophora. Em adição, alguns isolados de um mesmo ribotipo foram afiliados à ordem Mucorales e, outro, revelou ser uma potencial nova espécie pertencente ao filo Basidiomycota. O fungo Geomyces pannorum. AL1-1B foi selecionado como o melhor produtor de lipase e apresentou atividade de 761,68 U/L no 5° dia de cultivo em pH 8,0 a 15 °C, evidenciando o potencial biotecnológico na produção de lipase a baixas temperaturas. / Cold-active lipases are widely distributed in micro-organisms which survive in low temperatures, in this context; fungal isolation from Antarctic environment can be considered strategic for obtaining lipases at low temperatures. The present work aimed to assess the production of lipases and diversity of filamentous fungi isolated from samples of the Antarctic environment. A total of 253 isolates were retrieved from 10 marine and four terrestrial samples collected on the Antarctic continent, amongst then 68 presented positive results and were subjected to the experiments of lipase production evaluation and biodiversity characterization. Lipolytic fungi were identified as representatives of the genera: Geomyces, Penicillium, Cosmospora, Thelebolus, Chaetomium, Hypocrea, Antarctomyces, Mortierella and Cadophora. In addition, some isolates of the same ribotype were affiliated to the order Mucorales, and another one, showed to be a putative new species from phylum Basidiomycota. The fungus Geomyces pannorum AL1-1B was selected as the lipase best producer and showed activity of 761.68 U/L in the 5th day of cultivation at pH 8.0 at 15 °C, highlighting the biotechnological potential for lipase production at low temperatures.
3

Atividade lipolítica e biodiversidade de fungos filamentosos derivados da Antártica. / Lipase activity and biodiversity of filamentous fungi derived from Antarctica.

Fernando Suzigan Nobre 26 March 2013 (has links)
Lipases ativas em temperaturas frias estão amplamente distribuídas em micro-organismos que sobrevivem em temperaturas baixas, neste contexto, o isolamento de fungos de ambiente antártico pode ser considerado estratégico para obtenção de lipases a baixas temperaturas. O presente trabalho teve como objetivo avaliar a produção de lipases e a diversidade de fungos filamentosos isolados de amostras do ambiente Antártico. Um total de 253 isolados foi recuperado a partir de 10 amostras marinhas e quatro terrestres, dos quais 68 apresentaram resultados positivo e foram submetidos aos experimentos de avaliação da produção de lipase e caracterização da biodiversidade. Os fungos lipolíticos foram identificados como pertencentes aos gêneros: Geomyces, Penicillium, Cosmospora, Thelebolus, Chaetomium, Hypocrea, Antarctomyces, Mortierella e Cadophora. Em adição, alguns isolados de um mesmo ribotipo foram afiliados à ordem Mucorales e, outro, revelou ser uma potencial nova espécie pertencente ao filo Basidiomycota. O fungo Geomyces pannorum. AL1-1B foi selecionado como o melhor produtor de lipase e apresentou atividade de 761,68 U/L no 5° dia de cultivo em pH 8,0 a 15 °C, evidenciando o potencial biotecnológico na produção de lipase a baixas temperaturas. / Cold-active lipases are widely distributed in micro-organisms which survive in low temperatures, in this context; fungal isolation from Antarctic environment can be considered strategic for obtaining lipases at low temperatures. The present work aimed to assess the production of lipases and diversity of filamentous fungi isolated from samples of the Antarctic environment. A total of 253 isolates were retrieved from 10 marine and four terrestrial samples collected on the Antarctic continent, amongst then 68 presented positive results and were subjected to the experiments of lipase production evaluation and biodiversity characterization. Lipolytic fungi were identified as representatives of the genera: Geomyces, Penicillium, Cosmospora, Thelebolus, Chaetomium, Hypocrea, Antarctomyces, Mortierella and Cadophora. In addition, some isolates of the same ribotype were affiliated to the order Mucorales, and another one, showed to be a putative new species from phylum Basidiomycota. The fungus Geomyces pannorum AL1-1B was selected as the lipase best producer and showed activity of 761.68 U/L in the 5th day of cultivation at pH 8.0 at 15 °C, highlighting the biotechnological potential for lipase production at low temperatures.
4

Algoritam za poboljšanje termalnog komfora u urbanoj sredini / The algorithm for improving the thermal comfort in urban environment

Bajšanski Ivana 18 August 2016 (has links)
<p>Cilj ovog istraživanja je kreiranje algoritma za pobolj&scaron;anje spolja&scaron;njeg<br />termalnog komfora u velikim urbanim sredinama, uzimajući u obzir<br />određene geometrijske parametre izgrađenog okruženja, primenom<br />softverskih aplikacija za parametarsko modelovanje. Algoritam za<br />pobolj&scaron;anje spolja&scaron;njeg termalnog komfora ima opciju automatske<br />izmene lokacije čoveka, &scaron;to omogućava procenu termalnog komfora u<br />području velikih razmera, kao &scaron;to su bulevari, blokovski prostori, trgovi i<br />drugi. Takođe, algoritam za pobolj&scaron;anje spolja&scaron;njeg termalnog komfora<br />omogućava i automatsko menjanje visina zgrada u cilju postizanja<br />optimalnog urbanog dizajna koji podrazumeva najbolji spolja&scaron;nji termalni<br />komfor.</p> / <p>The aim of this research is to create an algorithm for improvement of<br />outdoor thermal comfort conditions in urban areas taking into account<br />certain geometrical parameters of built urban environment, applying<br />parametric modelling and different software packages. The algorithm<br />for improving the outdoor thermal comfort offers the option of<br />automated change of a man&rsquo;s location, which enables the evaluation<br />of outdoor thermal comfort in large-scale urban areas, such as<br />boulevards, courtyards, squares etc. In addition, the algorithm for<br />improving the outdoor thermal comfort also allows automatic<br />variations of building height in order to achieve the optimal urban<br />design which implies the best outdoor thermal comfort.</p>
5

Kompozitní materiály se silikátovou matricí do prostředí vysokých teplot / Composite materials with silica matrix in the environment of high temperatures

Lisztwanová, Ewa January 2017 (has links)
This thesis deals with the study and design of composite materials based on silica matrix suitable for extreme conditions, eg. for the repair of concrete structures with anticipated increased risk of fire. The theoretical part summarizes basic knowledge concerning the fire resistance of structures and the behavior of the composite system during extreme conditions. Theoretically oriented section also contains information on alkali-activated materials and their use in high temperature environments. Based on the evaluation of the theoretical part of the experiment were designed and tested different types of composite materials with increased content of raw materials from alternative sources. Laboratory research has been based on testing of basic physico-mechanical parameters including phase composition and microstructure of the proposed formulations before and after thermal exposure of 1200 ° C. Also considered was the effect of different cooling conditions.
6

Avaliação da produção de etanol em temperaturas elevadas por uma linhagem de S. cerevisiae. / Evaluation of ethanol production at high temperatures by a strain of S. cerevisiae.

Souza, Crisla Serra 24 April 2009 (has links)
A metodologia de superfície de resposta foi utilizada para otimizar as condições e obter maiores produção de etanol e viabilidade para a linhagem de S. cerevisiae 63M em processo descontínuo, resultando nas condições: 200 g.L-1 de sacarose, 40 g.L-1 de inóculo a 30 °C. Diferentes tipos de processos foram comparados e o processo que apresentou maiores viabilidade, produtividade e rendimento foi o descontínuo alimentado por pulsos de volumes decrescentes de sacarose a 30 °C. A redução da concentração de sacarose foi uma estratégia que permitiu aumentar a temperatura até 37 °C sem perdas em viabilidades. Uma linhagem utilizada nas destilarias brasileiras foi comparada com a linhagem 63M em temperaturas elevadas e observou-se que a 63M produziu maior produtividade e rendimento. Oito ciclos sucessivos de fermentação com reutilização de células da linhagem 63M foram realizados em meio sintético em processo descontínuo alimentado por pulsos de sacarose a 37 °C e uma perda gradual de viabilidade foi observada, mas o etanol final permaneceu constante nos oitos ciclos. / Surface response methodology was used to optimize the conditions and to obtain higher ethanol production and viability to strain 63M of S. cerevisiae in batch culture, resulting in the conditions: 200 g.L-1 sucrose, 40 g.L-1 inoculum at 30 °C. Different types of processes were compared and the process that presented higher viability, productivity and yield was pulse fed-batch using five decreasing pulses of sucrose at 30 °C. The reduction of the sucrose concentration was a strategy that allowed increasing the temperature up to 37 °C without losses in viabilities. An industrial strain used in Brazilian distilleries was compared with strain 63M at high temperatures and it was observed that strain 63M produced higher productivity and yield. Eight successive cycles of fermentation with reuse of cells of strain 63M were carried out in synthetic medium in fed-batch process using sucrose pulses at 37 °C and a gradual loss of viability was observed, but the final ethanol was kept constant in the eight fermentation cycles.
7

Avaliação da produção de etanol em temperaturas elevadas por uma linhagem de S. cerevisiae. / Evaluation of ethanol production at high temperatures by a strain of S. cerevisiae.

Crisla Serra Souza 24 April 2009 (has links)
A metodologia de superfície de resposta foi utilizada para otimizar as condições e obter maiores produção de etanol e viabilidade para a linhagem de S. cerevisiae 63M em processo descontínuo, resultando nas condições: 200 g.L-1 de sacarose, 40 g.L-1 de inóculo a 30 °C. Diferentes tipos de processos foram comparados e o processo que apresentou maiores viabilidade, produtividade e rendimento foi o descontínuo alimentado por pulsos de volumes decrescentes de sacarose a 30 °C. A redução da concentração de sacarose foi uma estratégia que permitiu aumentar a temperatura até 37 °C sem perdas em viabilidades. Uma linhagem utilizada nas destilarias brasileiras foi comparada com a linhagem 63M em temperaturas elevadas e observou-se que a 63M produziu maior produtividade e rendimento. Oito ciclos sucessivos de fermentação com reutilização de células da linhagem 63M foram realizados em meio sintético em processo descontínuo alimentado por pulsos de sacarose a 37 °C e uma perda gradual de viabilidade foi observada, mas o etanol final permaneceu constante nos oitos ciclos. / Surface response methodology was used to optimize the conditions and to obtain higher ethanol production and viability to strain 63M of S. cerevisiae in batch culture, resulting in the conditions: 200 g.L-1 sucrose, 40 g.L-1 inoculum at 30 °C. Different types of processes were compared and the process that presented higher viability, productivity and yield was pulse fed-batch using five decreasing pulses of sucrose at 30 °C. The reduction of the sucrose concentration was a strategy that allowed increasing the temperature up to 37 °C without losses in viabilities. An industrial strain used in Brazilian distilleries was compared with strain 63M at high temperatures and it was observed that strain 63M produced higher productivity and yield. Eight successive cycles of fermentation with reuse of cells of strain 63M were carried out in synthetic medium in fed-batch process using sucrose pulses at 37 °C and a gradual loss of viability was observed, but the final ethanol was kept constant in the eight fermentation cycles.
8

Vývoj kompozitů na bázi alkalicky aktivovaných matric odolných vůči působení extrémních teplot / The development of composites based on alkali-activated matrices resistant to extreme temperatures

Ševčík, Marek January 2021 (has links)
The diploma thesis is focused on the development of composites from alkali activated materials (AAM) and their resistance to extreme temperatures. The theoretical part describes alkaline activation and precursors for the production of AAM. Furthermore, the problem of the effect of extreme temperatures on these materials is described. In the experimental part, the optimal silicate modulus with respect to the properties of AAM was gradually determined, and the effect of extreme temperatures on the AAM matrix was verified. In the next stage, the effect of the filler with respect to the behavior at extreme temperatures was tested and then the final formulation was optimized.
9

Vývoj kompozitního materiálového systému se zaměřením na matrici pro extrémní podmínky / The development of composite material system with focus on matrix for extreme conditions

Gratclová, Kamila January 2016 (has links)
The thesis deals with composite systems, with a focus on matrix resistant to extreme conditions. The aim of this work was to research and development matrix, resistant to high temperatures, typical in case of fire. Used theoretical knowledge were realized with subsequent laboratory research. Attention was paid matrices based binder mixed with any alkali activation of alternative raw materials and geopolymers. Scattered reinforcement featured polypropylene fibers. The subject of the practical part of the two alternatives, including a matrix based on basic ingredients - cement, alternative raw materials - high fly ash, blast furnace slag, geopolymer and polymeric components incl. combinations thereof. Laboratory research conducted by determining the fundamental material properties such as density, strengths, etc., after heat exposure. The developed materials were subjected to a temperature 1400 ° C. The conclusion was selected several recipes that were based on the resulting values found to be optimal.

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