Dissertations / Theses on the topic 'Silicon alternatives'
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Rostkowska, Cristina. "Efeito da infusão de Artemisia annua cultivada em solo com aplicação de silicato de cálcio e magnésio sobre o controle de Toxoplasma gondii in vitro." Universidade Federal de Uberlândia, 2012. https://repositorio.ufu.br/handle/123456789/16579.
Full textToxoplasmosis is an important zoonotic disease due to ability of its causal agent, Toxoplasma gondii, to infect large number of vertebrates and to be associated with congenital infection or opportunistic disease in immunosuppressed patients. As the traditional treatment has shown adverse effects, low-toxicity compounds including artemisinin and its derivatives have been researched, as well Artemisina annua tea infusion. The use of silicon in the soil of A. annua crops and its role on artemisinin content has not been studied yet. This study aimed to investigate the effects of silicon on A. annua plant physiology and the role of the tea infusion obtained from these plants in the control of T. gondii infection in cell culture. The experimental design was a completely randomized design (CRD), in which A. annua was planted in the soil with five different doses of calcium/magnesium silicate (0, 200, 400, 800 and 1600 kg ha-1) and five replications, and maintained in a greenhouse. Analysis of foliar macronutrients showed a significant increase only for nitrogen, in the presence of the highest dose of silicate in the soil. The foliar micronutrient and Si concentrations as well the plant height were not significantly changed with any silicate doses in the soil. The use of 400 kg ha-1 of silicate induced the highest total glandular trichome area that was also associated with the intact glandular trichomes, as observed by scanning electron microscopy, and with the highest artemisinin content in plant leaves and tea infusion, as determined by thin layer chromatography (TLC) and high performance liquid chromatography (HPLC), respectively. HeLa cell treatments along with or after T. gondii infection, with infusion of A. annua grown in the soil without or with silicate (400 kg ha-1), induced a decrease of parasite proliferation in a dose-dependent manner, as also seen for cell treatment with pure artemisinin. In conclusion, the use of silicon had positive effect on the glandular trichome areas and artemisinin contents, but this outcome was not associated with a better efficacy of A. annua tea infusion on T. gondii replication. These findings suggest that other components rather than artemisinin could be contributing to this effect, such as flavonoids present in its leaves, which may act in synergism with the artemisinin and improve its efficacy.
A toxoplasmose é uma zoonose importante devido à capacidade de seu agente causal, Toxoplasma gondii, de infectar um grande número de vertebrados e ser associada com infecção congênita ou doença oportunista em pacientes imunocomprometidos. O tratamento tradicional mostra efeitos adversos levando à pesquisa de compostos de baixa toxicidade como a artemisinina, seus derivados e a infusão da planta Artemisia annua. A utilização de silício no solo de culturas de A. annua e seu papel no conteúdo de artemisinina ainda não foram estudados. O objetivo deste estudo foi investigar os efeitos do silício sobre a fisiologia da planta A. annua e o papel da infusão destas plantas sobre o controle da infecção de T. gondii em cultura celular. Foi utilizado o delineamento inteiramente ao acaso (DIC), no qual A. annua foi plantada em solo com aplicação de cinco diferentes dosagens de silicato de cálcio/magnésio (0, 200, 400, 800 e 1600 kg ha-1), em cinco repetições e mantida em casa de vegetação. A análise de macronutrientes foliares mostrou um aumento significativo apenas para o nitrogênio, na presença da maior dosagem de silicato no solo. As quantidades de micronutrientes e silício foliares bem como a altura da planta não foram significativamente alteradas em quaisquer dosagens de silicato no solo. A aplicação de 400 kg ha-1 de silicato induziu a maior área de tricomas glandulares totais que foi associada com os tricomas glandulares intactos, como observado por microscopia eletrônica de varredura, e com o mais alto conteúdo de artemisinina nas folhas e na infusão da planta, como determinado por cromatografia em camada fina (TLC) e cromatografia líquida de alta eficiência (HPLC), respectivamente. Os tratamentos de células HeLa, simultaneamente ou após a infecção por T. gondii, com infusão de A. annua cultivada sem ou com silicato (400 kg ha-1) aplicado ao solo, induziram decréscimo dependente da dose na proliferação parasitária, como também verificado para o tratamento das células com artemisinina pura. Em conclusão, o uso de silício teve efeito positivo sobre as áreas de tricomas glandulares e seu conteúdo de artemisinina, mas este resultado não foi associado com melhor eficácia da infusão de A. annua sobre a replicação intracelular de T. gondii. Estes resultados sugerem que outros componentes além da artemisinina poderiam contribuir para este efeito, como os flavonóides presentes nas folhas de A. annua que podem atuar em sinergismo com a artemisinina e melhorar a sua eficácia.
Doutor em Imunologia e Parasitologia Aplicadas
Åkerblom, Denize, and Erik Göranzon. "Greener Water Repellency? Feasible alternatives to fluoro chemicals for DWOR treatments on textiles." Thesis, Högskolan i Borås, Institutionen Textilhögskolan, 2014. http://urn.kb.se/resolve?urn=urn:nbn:se:hb:diva-17695.
Full textProgram: Textilingenjörsutbildningen
Daubriac, Richard. "Caractérisation de techniques d'implantations ioniques alternatives pour l'optimisation du module source-drain de la technologie FDSOI 28nm." Thesis, Toulouse, INSA, 2018. http://www.theses.fr/2018ISAT0031/document.
Full textDuring the past few decades, the emergence of new architectures (FDSOI, FinFETs or NW-FETs) and the use of new materials (like silicon/germanium alloys) allowed to go further in MOS devices scaling by solving short channel effect issues. However, new architectures suffer from contact resistance degradation with size reduction. This resistance strongly depends on two parameters: the active dopant concentration close to the semi-conductor surface and the Schottky barrier height of the silicide contact. Many solutions have been proposed to improve both of these physical parameters: pre-amorphisation, laser annealing, dopant segregation and others. In order to optimize the experimental conditions of these fabrication techniques, it is mandatory to measure precisely and reliably their impact on cited parameters.Within the scope of this thesis, two parts are dedicated to each lever of the contact resistance, each time precising the developed characterization method and concrete application studies. The first part concerns the study of the active dopant concentration close to the semi-conductor surface. In this axis, we developed a Differential Hall Effet method (DHE) which can provide accurate depth profiles of active dopant concentration combining successive etching processes and conventional Hall Effect measurements. To do so, we validated layer chemical etching and precise electrical characterization method for doped Si and SiGe. Obtained generated profiles have a sub-1nm resolution and allowed to scan the first few nanometers of layers fabricated by advanced ion implantation and annealing techniques, like solid-phase epitaxy regrowth activated by laser annealing. In the second part, we focused on the measurement of Schottky barrier height of platinum silicide contact. We transferred a characterization method based on back-to-back diodes structure to measure platinum silicide contacts with different dopant segregation conditions. The electrical measurements were then fitted with physical models to extract Schottky barrier height with a precision of about 10meV. This combination between measurements and simulations allowed to point out the best ion implantation and annealing conditions for Schottky barrier height reduction.To conclude, thanks to this project, we developed highly sensitive characterization methods for nanoelectronics application. Moreover, we brought several clarifications on the impact of alternative ion implantation and annealing processes on Si and SiGe ultra-thin layers in the perspective of contact resistance reduction in FDSOI source-drain module
Karecki, Simon Martin. "Alternative chemistries for etching of silicon dioxide and silicon nitride." Thesis, Massachusetts Institute of Technology, 1996. http://hdl.handle.net/1721.1/43304.
Full textIncludes bibliographical references (p. 123-126).
by Simon Martin Karecki.
M.S.
Madhavan, Atul. "Alternative designs for nanocrystalline silicon solar cells." [Ames, Iowa : Iowa State University], 2009. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:3403005.
Full textOrellana, Pérez Teresa. "Mechanical behavior of alternative multicrystalline silicon for solar cells." Doctoral thesis, Technische Universitaet Bergakademie Freiberg Universitaetsbibliothek "Georgius Agricola", 2013. http://nbn-resolving.de/urn:nbn:de:bsz:105-qucosa-117455.
Full textNortey, Philip Tetteybuah. "Alternative methods for the formation of chemically bonded phases for liquid chromatography." Thesis, Birkbeck (University of London), 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.340537.
Full textSilva, Raphael Tavares da. "Desenvolvimento de uma abordagem computacional para a tradução in silico de variantes de splicing detectadas no transcriptoma humano." reponame:Repositório Institucional da FIOCRUZ, 2012. https://www.arca.fiocruz.br/handle/icict/6406.
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Fundação Oswaldo Cruz. Instituto Oswaldo Cruz. Rio de Janeiro, RJ, Brasil.
Um dos mecanismos capaz de aumentar a diversidade do proteoma de eucariotos é o splicing alternativo nos pré-mRNAs. Este mecanismo celular ocorre durante a transcrição dos genes, sendo ocasionado por um ou mais dos seguintes eventos: retenção de íntrons, uso alternativo de sítio de splice 5', uso alternativo de sítio de splice 3' e uso alternativo de éxons. Análises recentes de Bioinformática utilizando experimentos de RNA-Seq mostram que aproximadamente 90% dos genes humanos produzem mais de um transcrito decorrente de eventos de splicing alternativo. O impacto do splicing alternativo no proteoma humano vem sendo alvo de algumas abordagens de Bioinformática, sendo esperado que uma grande porção de tais transcritos alternativos possa alterar o conteúdo da cadeia polipeptídica obtida após a sua tradução. Devido à sua importância, diversos trabalhos já foram desenvolvidos com o objetivo de facilitar a identificação de eventos de splicing alternativo a partir de dados provenientes de cDNA, bem como sua associação com a estrutura das proteínas de suas isoformas. Entretanto, são poucas as abordagens que realizaram a tradução in silico do transcriptoma humano na busca por variantes de splicing e a utilização de dados oriundos de sequenciadores de segunda geração (NGS) ainda é muito pouco explorada para tratar do tema. Desta maneira, o presente projeto tem como objetivo a aplicação de uma nova abordagem para a identificação e tradução de variantes de splicing alternativo usando dados de NGS. Foram utilizadas leituras da plataforma de sequenciamento Roche/454 oriundas de estudos de câncer para um enriquecimento de nosso banco de dados original que continha previamente mRNAs completos e ESTs. Após o enriquecimento, a metodologia empregada pelo nosso grupo conseguiu detectar 4.574 variantes de splicing inéditas em nosso banco. O novo banco gerado foi traduzido levando a criação de um repertório proteico contendo 159.638 sequências polipeptídicas não redundantes. Na busca por variantes inéditas utilizando dados de proteômica, foram identificadas três possíveis nos genes humanos tubulina 2b, tubulina 4b e actina. Dados de sequenciamento da plataforma Illumina também foram utilizados para uma avaliação da sua contribuição em número de variantes e sequências polipeptídicas traduzidas em nosso repertório. Encontramos que a nossa abordagem foi capaz de anotar 53% mais sequências polipeptídicas quando comparada ao repertório de ENSEMBL Gene. Desta forma, acreditamos que o presente projeto pode auxiliar no melhoramento da anotação de peptídeos encontrados por técnicas de proteômica, bem como no descobrimento de novos marcadores moleculares.
Alternative splicing of pre-mRNAs is one of the mechanisms capable to increase the proteome diversity in eukaryotes. This cellular mechanism occurs during the transcription of genes and is associated with one or more of the following events: intron retention, 5’ alternative splice, 3’ alternative splice and exon skipping. Recent Bioinformatics analysis using RNA-Seq experiments showed that approximately 90% of human genes produce more than one transcript due to alternative splicing events. The impact of alternative splicing in the human proteome has been the focus of some Bioinformatics approaches and is expected that the majority part of these alternative transcripts can alter the polypeptide chain produced after its translation. Due to its importance, many studies have been developed focused on facilitating the identification of alternative splicing events based on cDNA data, as well as to study the protein structure of its isoforms. However, few studies performed the in silico translation of the human transcriptome to search for new splicing isoforms using Next Generation Sequencing (NGS) data. In this way, our project aims to the development of a new approach to identify and translate alternative splicing isoforms using NGS data. Roche/454 reads of cancer studies were used to enrich our initial database, which was previously populated with full-length mRNAs and ESTs data. After the enrichment step, the methodology developed by our group could detect 4,574 new splicing variants in our database. The enriched database was translated, producing a protein repository with 159,638 non-redundant polypeptide sequences. Searching for new isoforms using experimental proteomic data, three possible new isoforms were identified for the human genes tubulin 2b, tubulin 4b and actin. Illumina sequencing data was used to assess its contribution for the number of new isoforms and the translated polypeptide sequences on our database. We realized that our approach was capable to annotate 53% more polypeptide sequences when compared with the ENSEMBL Gene repository. In this way, we believe that our project can support the improvement of peptide annotation found by proteomic techniques, as well as to discover new molecular markers.
Moreira, Ricco Isabel Maria. "Alternative oxidants and processing procedures for pyrotechnic time delays." Pretoria : [s.n.], 2004. http://upetd.up.ac.za/thesis/available/etd-09132005-115831.
Full textLi, Sonia Mary Seiwei. "Alternative approaches to silicon germanium modulation doped field effect transistor processing." Thesis, Imperial College London, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.408012.
Full textKwapil, Wolfram [Verfasser]. "Alternative materials for crystalline silicon solar cells : risks and implications / Wolfram Kwapil." Konstanz : Bibliothek der Universität Konstanz, 2010. http://d-nb.info/1017235988/34.
Full textStodilka, Danielle O. "Silicon carbide MIS and MOS development using alternative nitride and oxide dielectrics." [Gainesville, Fla.] : University of Florida, 2005. http://purl.fcla.edu/fcla/etd/UFE0013116.
Full textPysch, Damian [Verfasser]. "Assembly and Analysis of Alternative Emitter Systems for Silicon Solar Cells / Damian Pysch." München : Verlag Dr. Hut, 2011. http://d-nb.info/1015608159/34.
Full textZhu, Xingguang Williams John R. "Alternative growth and interface passivation techniques for SiO2 on 4H-SiC." Auburn, Ala, 2008. http://hdl.handle.net/10415/1494.
Full textKalkandjiev, Kiril [Verfasser], and Roland [Akademischer Betreuer] Zengerle. "Microfluidics based on silicon, polymer and all-polymer technologies as an alternative to silicon, glass: a case study for TopSpot printheads." Freiburg : Universität, 2015. http://d-nb.info/1119805597/34.
Full textChan, Julia Kam Chu 1972. "Alternative passivation for silicon (100), environmentally benign manufacturing, and cooperative strategy in semiconductor industry." Thesis, Massachusetts Institute of Technology, 2000. http://hdl.handle.net/1721.1/8850.
Full textIncludes bibliographical references (p. 118-120).
My personal involvement, as a research graduate student, sponsored by Engineering Research Center, a center created by National Science Foundation and Semiconductor Research Corporation demonstrates that, through industrial research staffs' mentoring, university research can bring innovative environmentally benign manufacturing methods to the U.S. semiconductor industry. Our group has used methoxy to protect the bare silicon surface, because we have identified that the industrial standard, hydrogen passivation of silicon (H-Si) degrades rapidly when exposes to air. In this thesis, two new processing steps are added to make this methoxy passivation compatible to industrial practice. In addition, a preliminary gate oxide test demonstrated that this methoxy terminated silicon (MeO-Si) yielded a thinner ultra thin gate oxide than those wafers cleaned by IBM's conventional RCA and dilute hydrofluoric acid last clean without compromising its reliability. Furthermore, particle count results shown that this MeO-Si has the same particle resistance as H-Si. Further mechanistic and thermodynamic studies are performed such that this process is optimized. As a result, MeO-Si is 49 times more stable than H-Si against air degradation. Through this center, an Environmental Safety and Health incorporated Cost of Ownership is developed in this thesis. This is done by using in vitro studies to evaluate the toxicity of new chemicals used, and by using lifecycle analysis to calculate the amount of untreated chemical, which leaks to the environment. Both of these will give rise to an environmental figure of merit to modify the conventional cost of ownership. In the last section, a strategic analysis of this Engineering Research Center is performed to demonstrated that students are a very important media to (1) facilitating technology transfer to industry, (2) enhancing collaboration along the chain of semiconductor industrial participants.
by Julia Kam Chu Chan.
S.M.
Adams, Curtis. "Studies on nitrogen and silicon deficiency in microalgal lipid production." DigitalCommons@USU, 2013. https://digitalcommons.usu.edu/etd/1955.
Full textLIMA, Meridiana Araújo Gonçalves. "Óleos essenciais e silício para controle da murcha bacteriana do tomateiro." Universidade Federal Rural de Pernambuco, 2016. http://www.tede2.ufrpe.br:8080/tede2/handle/tede2/6023.
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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES
Bacterial wilt caused by Ralstonia solanacearum (Rs) is one of the most important tomato diseases in Brazil. The effectiveness of ginger and melaleuca at 1%, rosemary at 0.50% and bergamot, lemongrass, clove, citronella, eucalyptus, sweet orange, palmrose and sage at 0.14% (v/v) essential oils was evaluated in vitro and via biofumigation of the soil infested with Rs. It was analyzed the in vitro growth; the population of Rs in soil before and seven days after biofumigation; and the components of resistance to disease and the growth of tomato plants cv. TY 2006, 15 days after transplanting. The clove oil was fractioned and its major chemical component was compared with the essencial oil in relation to the variables already cited. The in vitro growth of Rs was reduced by 100% with rosemary, lemongrass, citronella, clove, eucalyptus and palmrose oils. The population of Rs in soil was reduced by rosemary, clove, lemongrass, ginger, melaleuca and palmrose oils, with emphases for clove oil, which reduced Rs populations by 42.3%. The biofumigation with clove oil reduced the disease incidence, bacterial wilt index (BWI), and area under the disease curve progress (AUDPC) by 90.2, 97 and 98.8%, respectively and elevated the latent period by 10 days compared as the control with tween 20. The eugenol was the major constituent (87%) of the clove oil showing the same reduction effects of the components of disease resistance. The clove oil and the eugenol acetate did not reduce the height, and the fresh and dry biomass of plants. In asecond experiment, it was also evaluated the effect of silicon (Si) supplementation on the production of tomato transplants cultivars (cvs.) Santa Clara, TY 2006 and Yoshimatsu 4-11. The transplants were produced in substrate without Si (-Si) or with 3 g of calcium silicate de calcium/kg of substrate (+Si) and transplanted to Rs infected soil. After 15 days of growing it was evaluated the resistance components; the plant growth by measuring height, and the fresh and dry biomass of plants; the chlorophyll index; the Si content in plant tissues; the Rs population in stem base; and the enzymatic activity of phenylalanine amonia-lyases (PAL), β-1,3 glucanases (GLU) and peroxidases (POX). The Si supplementation on cvs. Santa Clara and TY 2006 reduced severity (33.2 and 42%), AUDPC (23.1 and 19.2%) and BWI (21.7 and 10%), respectively. The Si supplementation in the substrate did not affect plant growth, the chlorophyll index; the Si content in plant tissues and the Rs population in stem. Higher activities of PAL and GLU were evidenced on +Si plants. Therefore, the soil biofumigation with clove oil at 0.14% and the production of tomato transplants in substrate with Si have the potential to be integrated in the bacterial wilt management.
A murcha bacteriana causada por Ralstonia solanacearum (Rs) é uma das doenças economicamente mais importantes em tomateiro. Os óleos essenciais de gengibre e melaleuca a 1%, alecrim a 0,50% e bergamota, capim limão, cravo, citronela, eucalipto, laranja doce palmarosa e sálvia a 0,14% (v/v) foram testados in vitro e pela biofumigação do solo infestado com Rs. Foram avaliados o crescimento in vitro, a população de Rs no solo antes e sete dias depois da biofumigação, os componentes de resistência à doença e o crescimento das plantas em tomateiros da cv. TY 2006, aos 15 dias após o transplantio. O óleo de cravo foi fracionado e seu constituinte químico majoritário foi comparado com o óleo essencial quanto a redução da doença e demais variáveis citadas anteriormente. No ensaio in vitro, os óleos de alecrim, capim limão, citronela, cravo, eucalipto e palmarosa inibiram completamente o crescimento de Rs. A população de Rs no solo foi reduzida pelos óleos de alecrim, cravo, capim limão, gengibre, melaleuca e palmarosa, destacando-se o cravo com redução de 42,3%. A biofumigação com o óleo de cravo reduziu a incidência, o índice de murcha bacteriana (IMB) e a área abaixo da curva de progresso da doença (AACPD) em 90,2; 97 e 98,8%, respectivamente e elevou o período de latência - PL50 em 10 dias com relação a testemunha com Tween 20. Este óleo apresentou o eugenol como constituinte majoritário (87%), com os mesmos efeitos na redução dos componentes de resistência da doença. O óleo de cravo e o acetato de eugenol não reduziram a altura, biomassa fresca e seca das plantas. Em um segundo experimento, foi avaliado o efeito da suplementação do silício (Si) na produção de mudas de tomateiro das cultivares (cvs.) Santa Clara, TY 2006 e Yoshimatsu 4-11. As mudas foram produzidas em substrato sem silício (-Si) ou com 3 g de silicato de cálcio/kg de substrato (+Si) e transplantadas para solo com Rs. Aos 15 dias de cultivo, foram avaliados os componentes de resistência à doença; o crescimento das plantas, medindo-se a altura e o peso da biomassa fresca e seca, o índice reativo de clorofila; o conteúdo de Si na planta; a população de Rs no caule; e as atividades enzimáticas de fenilalanina amônia-liases (FAL), β-1,3 glucanases (GLU) e peroxidases (POX). A suplementação com Si nas cvs. Santa Clara e TY 2006 promoveu redução da doença avaliada pela severidade (33,2 e 42%), AACPD (23,1 e 19,2%) e IMB (21,7 e 10%), respectivamente. A suplementação com Si no substrato não afetou de forma significativa o crescimento das plantas, o índice reativo de clorofila, o acúmulo de Si nos tecidos das plantas e a população de Rs nos tecidos do caule. Foi evidenciada maior atividade enzimática de FAL e GLU nas plantas tratadas (+Si). Desta forma, a biofumigação do solo com o óleo de cravo a 0,14 % e a produção de mudas em substrato tratado com Si têm potencial como medidas a serem utilizadas no manejo da murcha bacteriana em tomateiro.
Petkowicz, Diego Ivan. "Zeólitas sintetizadas com fontes alternativas de silício e alumínio: aplicação em fotocatálise." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2009. http://hdl.handle.net/10183/16779.
Full textIn the present study, alternative silicon and aluminum sources for zeolite A synthesis were exploited, namely: rice husk submitted to calcination and to acid leaching, chrysotile in its natural form and after acid leaching, silica from reject material and aluminum foil. For comparative reasons, commercial pyrogenic silica was also employed as a silicon source. Raw materials, as well as the corresponding resulting ones were characterized by a group of spectroscopical, thermal, electrochemical, volumetric and microscopy techniques, namely: X-ray Diffraction (XRD) spectrometry, X-ray photoelectron spectroscopy (XPS), transmittance Fourier Transform infrared spectroscopy (FTIR), Diffuse reflectance infrared Fourier transform spectroscopy (DRIFTS), nitrogen adsorption, thermogravimetric analysis (TGA), ultraviolet-visible diffuse reflectance spectroscopy (DRS), atomic force microscopy (AFM), scanning electron microscopy (SEM), electron scanning microscopy combined with energy dispersive X-ray analysis (SEMEDX) and differential pulse voltammetry (DPV). For the zeolite synthesis, the evaluated parameters were: (i) nature of the silicon and aluminum sources; (ii) crystallization time; (iii) Si/Al molar ratio on the synthesis gel and (iv) influence of the stirring in the crystallization. Excepting for raw chrisotile, the other cases afforded the production of zeolite A with higy crystallinity and purity. The synthesized zeolite A started from the leached chrysotile showed high structural stability for longer periods of synthesis. Variation in Si/Al molar ratio led to the formation of the zeolite Y, which was pure when rice calcinated to 600ºC was employed as the source of silicon and, which resulted in a mixture of zeolite A and Y when used the leached crisotila. Zeolite A with high crystalinity and with big size grains were obtained in the case of using silica (reject), leached chrysotile and rice calcined at 600ºC as silicon source and aluminum foil as the source of aluminum. Degradation of dyes (methylene blue, direct blue 71 and yellow direct 8) and pharmaceutical (paracetamol) was evaluated by a series of in situ generated titania supported catalysts obtained from the impregnation of TiCl4 onto a series of zeolite, synthesized using rice husk and chrysotile as the silicon source, whice were later submitted to calcination. The resulting titania were in the form of anatase phase. The highest catalyst activity was reached with samples having 10 wt.% Ti, being comparable to that exhibited by commercial P25 after one hour of UV light exposition. Experiments carried out in natural sunlight reached 92% decomposition of the methylene blue dye. The catalyst activity of a supported titania catalyst was shown to be kept until five cycles.
Sexton, Alexandra Elizabeth. "Eating for the post-Anthropocene : alternative proteins, Silicon Valley and the (bio)politics of food security." Thesis, King's College London (University of London), 2018. https://kclpure.kcl.ac.uk/portal/en/theses/eating-for-the-postanthropocene(2e88cc17-8f6f-4f86-9f8f-fdb485ebd0cd).html.
Full textDemchikhin, Sergey. "Alternativy likvidace fotovoltaických článků jako potenciální ekologické zátěže." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2012. http://www.nusl.cz/ntk/nusl-219643.
Full textDehouck, Yves. "Développement de potentiels statistiques pour l'étude in silico de protéines et analyse de structurations alternatives." Doctoral thesis, Universite Libre de Bruxelles, 2005. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/211040.
Full textLe premier aspect de notre travail concerne le développement de potentiels statistiques dérivés de bases de données de protéines dont les structures sont connues. Ces potentiels présentent plusieurs avantages: ils peuvent être aisément adaptés à des représentations structurales simplifiées, et permettent de définir un nombre limité de fonctions énergétiques qui incarnent l'ensemble complexe d'interactions gouvernant la structure et la stabilité des protéines, et qui incluent également certaines contributions entropiques. Cependant, leur signification physique reste assez nébuleuse, car l'impact des diverses hypothèses nécessaires à leur dérivation est loin d'être clairement établi. Nous nous sommes attachés à l'étude de certaines limitations des ces potentiels: leur dépendance en la taille des protéines incluses dans la base de données, la non-additivité des termes de potentiels, et l'importance souvent négligée de l'environnement protéique spécifique ressenti par chaque résidu. Nous avons ainsi mis en évidence que l'influence de la taille des protéines de la base de données sur les potentiels de distance entre résidus est spécifique à chaque paire d'acides aminés, peut être relativement importante, et résulte essentiellement de la répartition inhomogène des résidus hydrophobes et hydrophiles entre le coeur et la surface des protéines. Ces résultats ont guidé la mise au point de fonctions correctives qui permettent de tenir compte de cette influence lors de la dérivation des potentiels. Par ailleurs, la définition d'une procédure générale de dérivation de potentiels et de termes de couplage a rendu possible la création d'une fonction énergétique qui tient compte simultanément de plusieurs descripteurs de séquence et de structure (la nature des résidus, leurs conformations, leurs accessibilités au solvant, ainsi que les distances qui les séparent dans l'espace et le long de la séquence). Cette fonction énergétique présente des performances nettement améliorées par rapport aux potentiels originaux, et par rapport à d'autres potentiels décrits dans la littérature.
Le deuxième aspect de notre travail concerne l'application de programmes basés sur des potentiels statistiques à l'étude de protéines qui adoptent des structures alternatives. La permutation de domaines est un phénomène qui affecte diverses protéines et qui implique la génération d'un oligomère suite à l'échange de fragments structuraux entre monomères identiques. Nos résultats suggèrent que la présence de "faiblesses structurales", c'est-à-dire de régions qui ne sont pas optimales vis-à-vis de la stabilité de la structure native ou qui présentent une préférence marquée pour une conformation non-native en absence d'interactions tertiaires, est intimement liée aux mécanismes de permutation. Nous avons également mis en évidence l'importance des interactions de type cation-{pi}, qui sont fréquemment observées dans certaines zones clés de la permutation. Finalement, nous avons sélectionné un ensemble de mutations susceptibles de modifier sensiblement la propension de diverses protéines à permuter. L'étude expérimentale de ces mutations devrait permettre de valider, ou de raffiner, les hypothèses que nous avons proposées quant au rôle joué par les faiblesses structurales et les interactions de type cation-{pi}. Nous avons également analysé une autre protéine soumise à d'importants réarrangements conformationnels: l'{alpha}1-antitrypsine. Dans le cas de cette protéine, les modifications structurales sont indispensables à l'exécution de l'activité biologique normale, mais peuvent sous certaines conditions mener à la formation de polymères insolubles et au développement de maladies. Afin de contribuer à une meilleure compréhension des mécanismes responsables de la polymérisation, nous avons cherché à concevoir rationnellement des protéines mutantes qui présentent une propension à polymériser contrôlée. Des tests expérimentaux ont été réalisés par le groupe australien du Professeur S.P. Bottomley, et ont permis de valider nos prédictions de manière assez remarquable.
The work presented in this thesis concerns the computational study of the relationships between the sequence of a protein and its three-dimensional structure(s). The unravelling of these relationships has many applications in different domains and is probably one of the most fascinating issues in molecular biology.
The first part of our work is devoted to the development of statistical potentials derived from databases of known protein structures. These potentials allow to define a limited number of energetic functions embodying the complex ensemble of interactions that rule protein folding and stability (including some entropic contributions), and can be easily adapted to simplified representations of protein structures. However, their physical meaning remains unclear since several hypotheses and approximations are necessary, whose impact is far from clearly understood. We studied some of the limitations of these potentials: their dependence on the size of the proteins included in the database, the non-additivity of the different potential terms, and the importance of the specific environment of each residue. Our results show that residue-based distance potentials are affected by the size of the database proteins, and that this effect can be quite strong, is residue-specific, and seems to result mostly from the inhomogeneous partition of hydrophobic and hydrophilic residues between the surface and the core of proteins. On the basis of these observations, we defined a set of corrective functions in order to take protein size into account while deriving the potentials. On the other hand, we developed a general procedure of derivation of potentials and coupling terms and consequently created an energetic function describing the correlations between several sequence and structure descriptors (the nature of each residue, the conformation of its main chain, its solvent accessibility, and the distances that separate it from other residues, in space and along the sequence). This energetic function presents a strongly improved predictive power, in comparison with the original potentials and with other potentials described in the literature.
The second part describes the application of different programs, based on statistical potentials, to the study of proteins that adopt alternative structures. Domain swapping involves the exchange of a structural element between identical proteins, and leads to the generation of an oligomeric unit. We showed that the presence of “structural weaknesses”, regions that are not optimal with respect to the folding mechanisms or to the stability of the native structure, seems to be intimately linked with the swapping mechanisms. In addition, cation-{pi} interactions were frequently detected in some key locations and might also play an important role. Finally, we designed a set of mutations that are likely to affect the swapping propensities of different proteins. The experimental study of these mutations should allow to validate, or refine, our hypotheses concerning the importance of structural weaknesses and cation-{pi} interactions. We also analysed another protein that undergoes large conformational changes: {alpha}1-antitrypsin. In this case, the structural modifications are necessary to the proper execution of the biological activity. However, under certain circumstances, they lead to the formation of insoluble polymers and the development of diseases. With the aim of reaching a better understanding of the mechanisms that are responsible for this polymerisation, we tried to design mutant proteins that display a controlled polymerisation propensity. An experimental study of these mutants was conducted by the group of Prof. S.P. Bottomley, and remarkably confirmed our predictions.
Doctorat en sciences appliquées
info:eu-repo/semantics/nonPublished
Touma, Wissam Elias. "Alkali-silica reaction in Portland cement concrete : testing methods and mitigation alternatives /." Digital version accessible at:, 2000. http://wwwlib.umi.com/cr/utexas/main.
Full textTarvornpanich, Tarnkamol. "Recycled colourless soda-lime-silica glass as an alternative flux in whitewares." Thesis, University of Sheffield, 2007. http://etheses.whiterose.ac.uk/14505/.
Full textMiotti, Leonardo. "Transporte atômico e estabilidade em dielétricos alternativos para a tecnologia do Si." reponame:Biblioteca Digital de Teses e Dissertações da UFRGS, 2007. http://hdl.handle.net/10183/10724.
Full textThis thesis reports on experimental investigation of atomic transport and chemical reaction phenomena in ultrathin dielectric films on Si. These materials are alternative to silicon oxide used in metal-oxide-semiconductors based devices. The dielectrics investigated were: hafnium silicate and aluminate, lanthanum aluminate, and aluminum oxide/hafnium oxide bilayers. The main aim of the investigation here reported is the stability of structures against two critical steps of the fabrication process. The first one is post-deposition annealing, usually performed at temperatures between 600 and 800 C. The second one is source and drain dopant activation of the fabricated metal-oxide-semiconductor field effect transistors, which is usually performed at temperatures around 1000 C for times around 10 s. The production of the structures was accomplished by different deposition methods, among them reactive sputtering and atomic layer deposition. The observation of the thermal stability induced phenomena was accomplished with different characterization methods, such as high, medium, and low energy ion scattering, narrow nuclear reaction profiling, photoelectron spectroscopy, atomic resolution electron microscopy, and I×V and C×V characteristics. The results showed that the critical fabrication steps of advanced, nanoscopic microelectronic devices lead to atomic transport of different species and interfacial chemical reactions in the dielectrics on Si. In many cases this is not in agreement with the expectations based only on the formation energy of the concerned compounds. This trend is strongly modified according to the annealing atmospheres (nitrogen, oxygen, and their mixtures) as well by the introduction of nitrogen in the films.
Beaudoing, Emmanuel. "Etude in silico de la polyadénylation alternative, un système de régulation post-transcriptionnelle de l'expression génique." Aix-Marseille 2, 2001. http://www.theses.fr/2001AIX22036.
Full textRedondo, Simone Ungari Azzolino. "Avaliação da potencialidade do uso de fibras de Eucalyptus como reforço alternativo em compositos de silicona." [s.n.], 2003. http://repositorio.unicamp.br/jspui/handle/REPOSIP/250501.
Full textTese (doutorado) - Universidade Estadual de Campinas, Instituto de Quimica
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Doutorado
Matt, Hughes. "Silica supported transition metal phosphides : alternative materials for the water-gas shift reaction." Thesis, University of Glasgow, 2014. http://theses.gla.ac.uk/5548/.
Full textFilho, José Cândido de Souza. "Uma geometria alternativa para detecção do espalhamento de luz LASER por partículas e micro-rugosidades em superfícies de silício." Universidade de São Paulo, 2008. http://www.teses.usp.br/teses/disponiveis/3/3140/tde-30092008-145835/.
Full textIn this work, it is proposed an alternative geometry to detect LASER light scattering to obtain the average size and concentration of particles adhered on silicon wafers with different surface finishing. It was used a theoretical model for light scattering from dieletric particles which were previously deposited onto polished surfaces. This model is based on the analitical scattering theory of suspended particles developed by Gustav Mie26 which was adapted for particles adhered on silicon surfaces28,29. To characterize our Home-Built Equipment, it was used different samples with different surface features: silicon wafers with LATEX spheres of four different diameters (0.1 mm, 0.6 mm, 1.1 mm and 5.0 mm), surface lines with different width, height and inter-spacing, and liquid micro-drops of glicerine with several diameters (500-1800 mm). We have obtained the total intensity of scattered light as a function of the scattering section for each mentioned feature. Also, particle counting and, in some cases, measurements of horizontal assimetry of the particles were done. The light scattering measurements of particles and micro-drops were modeled using the Unbstructed Reflection Model to obtain the scattering sections with the aid of a calculation routine as proposed by Bohren and Huffman.
Taillet, Brice. "Procédés alternatifs pour l'élaboration de matériaux composites à matrice céramique." Thesis, Bordeaux, 2014. http://www.theses.fr/2014BORD0203/document.
Full textThe opening of the civil aviation market to ceramic matrix composite materials requires the development of new methods of producing compatible with the production rates and manufacturing costs of the sector.For this purpose, experimental work was conducted to develop a silicon oxynitride matrix (Si2N2O) by combustion synthesis (or SHS), from reactive powders. In recent years, Si2N2O has emerged as a promising new high-temperature ceramic material, characterized by not only good mechanical properties, but also by a higher oxidation resistance than silicon carbide. The underlying basis of SHS relies on the ability of highly exothermic reactions to be self-sustaining and, therefore, energetically efficient. Powders are first milled, dispersed and stabilized in aqueous media, and then impregnated into a fibrous preform composed of the latest generation of silicon carbide fibers (Hi-Nicalon S). SHS reaction is then carried out in a reactor specially designed and dedicated to this study. Particular attention was focused on the optimization of experimental parameters for the synthesis of a Si2N2O based matrix. Silicon metal in a mixture with silica powder was combusted under pressurized nitrogen gas into silicon oxynitride. The pressure and the temperature rise rate were the principal parameters for the composition and microstructure of the matrix. These parameters have been the subject of extensive experimental work to reach a homogeneous matrix with a very high formation rate for silicon oxynitride (more than 90wt%) and with a level of residual porosity lower than 10%. This work was completed by the calculation of the physical properties of the matrix, by the mechanical characterization of the composite material, and finally by a temperature aging test under moist air
Zhang, Yugao. "An alternative preparation of organofunctionalized silica gels and their characterization by solid-state NMR spectroscopy." Thesis, University of British Columbia, 1991. http://hdl.handle.net/2429/29889.
Full textScience, Faculty of
Chemistry, Department of
Graduate
Field, M. "In vitro and in silico examination of the alternative respiratory NADH dehydrogenase family in Arabidopsis thaliana and other species." Thesis, University College London (University of London), 2007. http://discovery.ucl.ac.uk/1444705/.
Full textPotié, Alexis. "Etude de la croissance de nanofils de Si Ge et caractérisation par microscopie à force atomique." Phd thesis, Université de Grenoble, 2012. http://tel.archives-ouvertes.fr/tel-00767918.
Full textAmit, Kumar. "Food irradiation and development of an alternative method for the detection of 2-Alkylcylcyclobutanone." Kansas State University, 2008. http://hdl.handle.net/2097/592.
Full textFood Science Institute
J. Scott Smith
Food irradiation is one of the most important food processing methods utilized to reduce microbial load and extend shelf life. In 1995 the World Health Organization (WHO) declared irradiated foods to be safe from a nutritional and toxicological point of view. Various methods have been applied to detect irradiated foods. Detection of 2-alkylcyclobutanones has been found to be a useful method in identifying irradiated foods. The solvent extraction method utilizes a Soxhlet apparatus for lipid extraction followed by clean up with Florisil. However, this method is very time consuming. The other methods available to detect 2-alkylcyclobutanone include supercritical fluid extraction (SFE), and accelerated solvent extraction method using a Dionex ASE 200 instrument. The SFE is a fast method to detected 2-alkylcyclobutanone. All the above mentioned methods involve costly equipment. The aim of this study was to eliminate the requirement of costly extraction equipment for lipid extraction before clean up or direct isolation of 2-alkylcyclobutanone as in case of SFE instrument using Florisil cartridges. In this study, the manual solvent extraction method was applied to isolate alkylcylcobutanone followed by clean up with 2 g silica cartridge. The clean up extract was injected to gas chromatography-flame ionization detector (GC-FID) for detection of 2-dodecylcyclobutanone (2-DCB). Gas chromatography-mass spectrometry (GC-MS) was used to confirm that the compound detected was 2-dodecylcyclobutanone. The ions m/z 98 and 112 were selected for 2-DCB for monitoring in selected ion monitoring (SIM) mode of GC-MS. The results showed that this method was able to detect 2-DCB from irradiated ground beef. The manual method does not require costly equipment such as supercritical fluid extractor, Dionex, or Soxlet apparatus for extraction process.
Orellana, Pérez Teresa [Verfasser], Hans Joachim [Akademischer Betreuer] Möller, Hans Joachim [Gutachter] Möller, and Cano Jose Ygnacio [Gutachter] Pastor. "Mechanical behavior of alternative multicrystalline silicon for solar cells / Teresa Orellana Pérez ; Gutachter: Hans Joachim Möller, Jose Ygnacio Pastor Cano ; Betreuer: Hans Joachim Möller." Freiberg : Technische Universitaet Bergakademie Freiberg Universitaetsbibliothek "Georgius Agricola", 2013. http://d-nb.info/122083727X/34.
Full textGarros, Xavier. "Caractérisation et modélisation de l'oxyde d'hafnium comme alternative à la silice pour les futures technologies CMOS submicroniques." Aix-Marseille 1, 2004. http://www.theses.fr/2004AIX11067.
Full textLIMA, Liliane Andrade. "Síntese de peneiras moleculares MCM-41 impregnadas com Co e Co/Ru utilizando fontes alternativas de sílica." Universidade Federal de Campina Grande, 2015. http://dspace.sti.ufcg.edu.br:8080/jspui/handle/riufcg/433.
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Este trabalho teve como objetivo sintetizar e caracterizar a peneira molecular mesoporosa MCM-41, utilizando diferentes fontes de sílica, e desenvolver catalisadores a base de cobalto e rutênio. As peneiras moleculares MCM-41 foram sintetizadas utilizando-se como fonte de sílica as cinzas de casca de arroz, cinzas de bagaço de cana-de-açúcar, argila chocolate B e Sílica Aerosil 200 com a seguinte base molar: 1,0 CTMABr:4,0 SiO2:1 Na2O:200 H2O. As peneiras moleculares MCM41 obtidas foram calcinadas em mufla a 600 °C por 7 horas. A deposição dos metais (cobalto e rutênio) sobre o suporte MCM-41 foi realizada por meio de impregnação úmida e depois calcinada. As amostras obtidas foram caracterizadas pelas técnicas de Espectroscopia de Fluorescência e Raios X por Energia Dispersiva (FRX-ED), Difração de raios X (DRX), Adsorção Física de Nitrogênio, Microscopia Eletrônica de Varredura (MEV) e Espectroscopia na Região do Infravermelho com Transformada de Fourier (FTIR). Os resultados mostraram ser possível obter a peneira molecular MCM-41 com diferentes fontes de sílica, pelas micrografias observa-se que os materiais apresentam morfologias similares, constituídas por aglomerados com forma esponjosa. Os difratogramas dos catalisadores mostraram que após a impregnação dos metais e calcinação, não ocorreram modificações na estrutura hexagonal. A partir dos resultados de Adsorção Física de N2, observou-se isotermas de adsorção do tipo IV, típico de materiais mesoporosos e altos valores de área superficial. Os catalisadores apresentaram composições de metais nas proporções pré-definidas e após impregnação do rutênio obteve melhor dispersão dos metais sobre a peneira molecular. Os espectros apresentaram bandas na região de 500 - 4000 cm-1, características das vibrações fundamentais dos grupos funcionais específicos presentes na estrutura da peneira molecular MCM-41 e bandas referentes a estrutura do óxido de cobalto (Co3O4).
This study aimed to synthesize and characterize the molecular sieve mesoporous MCM-41, using different sources of silica, and develop cobalt-based catalysts and ruthenium. The MCM-41 molecular sieves were synthesized using as silica source the rice husk ash, ash from sugarcane bagasse, clay chocolate B and silica Aerosil 200 with the following molar basis: 1.0 CTMABr: 4.0 SiO2: 1 Na2O: 200 H2O. The MCM-41 molecular sieves were obtained calcined in a muffle at 600 ° C for 7 hours. The deposition of metals (cobalt and ruthenium) on the supporting MCM-41 was performed by wet impregnation and then calcined. The samples obtained were characterized by spectroscopy techniques Fluorescence and X-rays by Energy Dispersive (FRX-ED), X-ray diffraction (XRD), Adsorption Nitrogen Physics, Scanning Electron Microscopy (SEM) and Fourier transform infrared spectroscopic (FTIR). The results proved possible to obtain MCM-41 molecular sieve having different silica sources, the micrographs it is noted that the materials have similar morphology, consisting of spongy form agglomerates. The XRD patterns of the catalysts showed that after impregnation and calcination of the metal, there were no changes in the hexagonal structure. From the results of Physical Adsorption of N2 was observed adsorption isotherms of type IV, typical of mesoporous materials and high surface area values. The metal catalyst compositions presented in predefined proportions and after impregnation of the obtained ruthenium better dispersion of metals on the molecular sieve. The spectra showed bands in the region of 500 - 4000 cm-1, characteristic of the fundamental vibrations of the specific functional groups present in the structure of the molecular sieve MCM-41 and bands related to the structure of the cobalt oxide (Co3O4).
Kelly, Brennan James. "Experimental and Simulated Analysis of Voltage Stress Within a Bar-Wound Synchronous Machine Excited by a Silicon Carbide Inverter." The Ohio State University, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=osu1619111736344023.
Full textKostura, Patrik. "Vývoj vysokohodnotného pórobetonu při využití alternativních zdrojů." Master's thesis, Vysoké učení technické v Brně. Fakulta stavební, 2019. http://www.nusl.cz/ntk/nusl-392332.
Full textSantos, Felipe Antunes. "Vitrocerâmica à base de silicato de lítio para uso como material dentário utilizando casca de arroz como fonte alternativa de silica." Universidade de São Paulo, 2013. http://www.teses.usp.br/teses/disponiveis/97/97133/tde-08102013-084019/.
Full textThis work suggests the replacement of commercial silica by silica obtained from rice husk as alternative source for obtaining lithium disilicate material that can be used in dental application. The lithium disilicate as dental material is a glass-ceramic that has good mechanical properties and chemical stability. For these developments the materials have been obtained using stoichiometry of 33.33%mol. Li2O and 66.67%mol. SiO2, without complementary oxide addition or with, seeking better fracture toughness comportment, to both sources of silica, commercial and from rice husk. As initial characterization X-ray diffraction (XRD) was performed for the mixtures of materials before and after the fusion to obtain the glasses. For materials without oxide addition, the two materials developed were characterized for their devitrification, in other words, the transition from glass to glass-ceramic was observed by differential thermal analysis (DTA), using different heating rates and granulometries. Peak crystallization temperatures (Tp), to both silica sources, heat rate 10°C/min and 1mm of granulometry, was in average values of 640°C. The DTA was used to verify the devitrification in material with oxide addition too. In addition, to observe the possible formation of intermediate phases on stoichiometric system of lithium disilicate, were also carried out high temperature X-ray diffractomery (HTXRD). To view the microstructural changes occurring in the system, according to the variation of heat treatments temperatures (HT), silica source and oxides influence, characterizations were performed by scanning electron microscopy (SEM). The cytotoxic behavior of the materials in cell colonies was observed by the cytotoxicity test. Mechanical properties, Vickers hardness and fracture toughness, were determined by calculus, using Vickers test data. Values of approximately 1.75 MPam½ were obtained for both silica sources with oxide addition to 660°C (HT). Results obtained show great potential in the replacement of commercial silica by rice husk silica.
Roberts, Alan Clive. "The Development of Facial Prosthetics and Adhesives in Plastic and Reconstructive Surgery. A study in the application of prosthetic materials and devices used in plastic and reconstructive surgery together with tissue adhesives as an alternative to conventional ligation." Thesis, University of Bradford, 1988. http://hdl.handle.net/10454/5065.
Full textAbedrrabba, Sarra. "Solutions innovantes pour des filtres de fréquences volumiques et semi-volumiques performants, en céramique, silice fondue et thermoplastique COC/COP... : nouvelles alternatives pour les futurs programmes de satellite multimédia." Thesis, Brest, 2017. http://www.theses.fr/2017BRES0126/document.
Full textThe emergence of satellite high-speed internet for the coverage of rural zones is accompanied by numerous technological constraints. The current trend is to use higher frequency bands to release the satellite capacity for users. The increasing frequency requires new considerations especially for filtering needs which become notably strict in terms of performance and integration in small integrated circuits. This work introduces filtering solutions based on high quality factor Substrate Integrated Waveguides (SIW) using a novel 3D transition for a better integration in widely planar Hybrid ICs.The first chapter introduces the study’s context and the different elements justifying the use of the SIW technology.In fact, these structures profit from both the good quality factors of TE-modes propagating in the substrate and the easy fabrication process and integration of planar circuits. However, to increase the SIW quality factor, the substrate’s height should be increased which induces interconnection limitations such as long bond wires with high parasitic effects and large microstrip access lines with discontinuity problems and the propagation of parasitic modes. The adopted approach consists in imagining 3D shapes providing both mode and thickness matching between a microstrip line etched on a thin substrate and a high substrate SIW.The second chapter introduces the different manufacturing processes used for the substrate’s shaping and metallization. Three substrates are considered: Alumina, fused Silica and Cyclo Olefin Polymer COC. Alumina is widely used in space applications and has a well-mastered process. For equivalent dielectric losses, fused silica has a lower permittivity for bigger structures with less manufacturing tolerance sensitivity. Both Alumina and fused silica substrates are shaped using a laser ablation. The reachable substrate’s height using this machining method is relatively low. The polymer solution (COP) is elaborated using a molding process allowing higher substrates heights.The last chapter outlines the design steps of the different solutions and the measurement results of the first prototypes. These results are on the whole encouraging but require further development
Jerban, Majid. "Performance of concrete incorporating amorphous silica residue and biomass fly ash." Mémoire, Université de Sherbrooke, 2016. http://hdl.handle.net/11143/9807.
Full textAbstract : Cement manufacturing industry is one of the carbon dioxide emitting sources. The global cement industry contributes about 7% of greenhouse gas emission to the earth’s atmosphere. In order to address environmental effects associated with cement manufacturing and constantly depleting natural resources, there is necessity to develop alternative binders to make sustainable concrete. Thus, many industrial by-products have been used to partially substitute cement in order to generate more economic and durable concrete. The performance of a cement additive depends on kinetics hydration and synergy between additions and Portland cement. In this project, two industrial by-products are investigated as alternative supplementary cementitious materials (ASCMs), non-toxic amorphous silica residue (AmSR) and wastepaper sludge ash (WSA). AmSR is by-product of production of magnesium from Alliance Magnesium near of Asbestos and Thetford Mines Cities, and wastepaper sludge ash is by-product of combustion of de-inking sludge, bark and residues of woods in fluidized-bed system from Brompton mill located near Sherbrooke, Quebec, Canada. The AmSR is new industrial by-products. Recently, wastepaper sludge ash has been used as cementitious materials. Utilization of these ashes as cementitious material in concrete manufacturing leads to reduce the mechanical properties of concretes. These problems are caused by disruptive hydration products of biomass fly ash once these ashes partially blended with cement in concrete manufacturing. The pre-wetting process of WSA before concrete manufacturing reduced disruptive hydration products and consequently improved concrete mechanical properties. Approaches for investigation of WSA in this project consist on characterizing regular and pre-wetted WSA, the effect of regular and pre-wetted WSA on performance of mortar and concrete. The high content of amorphous silica in AmSR is excellent potential as cementitious material in concrete. In this project, evaluation of AmSR as cementitious materials consists of three steps. Characterizing and determining physical, chemical and mineralogical properties of AmSR. Then, effect of different rates of replacement of cement by AmSR in mortar. Finally, study of effect of AmSR as partial replacement of cement in different concrete types with binary and ternary binder combinations. This study revealed that high performance concrete (HPC) incorporating AmSR showed similar mechanical properties and durability, compared to control mixture. AmSR improved mechanical properties and durability of ordinary concrete. Self-consolidating (SCC) concrete incorporating AmSR was stable, homogenous and showed good mechanical properties and durability. AmSR had good synergy in ternary binder combination with other supplementary cementitious materials (SCMs). This study showed AmSR can be use as new cementitious materials in concrete.
Montenegro, Danielle Lobo. "Reforma a seco de metano com catalisadores Ni/MCM-41 sintetizados a partir de fontes alternativas de s?lica." Universidade Federal do Rio Grande do Norte, 2013. http://repositorio.ufrn.br:8080/jspui/handle/123456789/12986.
Full textConselho Nacional de Desenvolvimento Cient?fico e Tecnol?gico
The production of synthesis gas has received renewed attention due to demand for renewable energies to reduce the emissions of gases responsible for enhanced greenhouse effect. This work was carried out in order to synthesize, characterize and evaluate the implementation of nickel catalysts on MCM-41 in dry reforming reactions of methane. The mesoporous molecular sieves were synthesized using as silica sources the tetraethyl orthosilicate (TEOS) and residual glass powder (PV). The sieves were impregnated with 10% nickel to obtain the metallic catalysts (Ni/MCM-41). These materials were calcined and characterized by Thermogravimetric Analysis (TG), Infrared spectroscopy (FTIR), X-ray Diffraction (XRD), Temperature-Programmed Reduction (TPR) and N2 Adsorption/Desorption isotherms (BET/BJH). The catalytic properties of the samples were evaluated in methane dry reforming with CO2 in order to produce synthesis gas to be used in the petrochemical industry. The materials characterized showed hexagonal structure characteristic of mesoporous material MCM-41 type, being maintained after impregnation with nickel. The samples presented variations in the specific surface area, average volume and diameter of pores based on the type of interaction between the nickel and the mesoporous support. The result of the the catalytic tests showed conversions about 91% CO2, 86% CH4, yelds about 85% CO and 81% H2 to Ni/MCM-41_TEOS_C, and conversions about 87% CO2, 82% CH4, yelds about 70% CO and 59% H2 to Ni/MCM-41_PV_C. The similar performance confirms that the TEOS can be replaced by a less noble materials
A produ??o de g?s de s?ntese tem recebido muita import?ncia devido a procura por fontes de energias renov?veis para reduzir as emiss?es dos gases respons?veis pelo aumento do efeito estufa. Este trabalho foi realizado com o objetivo de sintetizar, caracterizar e avaliar a aplica??o dos catalisadores de n?quel sobre MCM-41, em rea?oes de reforma a seco de metano. As peneiras moleculares mesoporosas foram sintetizadas utilizando como fontes de s?lica o Tetraetil Ortosilicato (TEOS) e o res?duo de p? de vidro (PV). As peneiras foram impregnadas com 10% de n?quel para forma??o dos catalisadores met?licos (Ni/MCM-41). Esses materiais foram calcinados e caracterizados por Termogravimetria (TG), Espectroscopia na Regi?o do Infravermelho (FTIR), Difratometria de raios X (DRX), Redu??o de Temperatura Programada (TPR) e Adsor??o e Dessor??o de N2 (BET/BJH). As propriedades catal?ticas das amostras foram avaliadas na reforma a seco de metano com CO2, tendo como objetivo a produ??o de g?s de s?ntese para utiliza??o na ind?stria petroqu?mica. Os materiais caracterizados apresentaram estrutura hexagonal caracter?stica do material mesoporoso tipo MCM-41, sendo mantida ap?s a impregna??o com n?quel. As amostras apresentaram varia??es quanto ? ?rea superficial espec?fica e volume m?dio de poros, em fun??o do tipo de intera??o existente entre o n?quel e o suporte mesoporoso. Os resultados dos testes catal?ticos mostraram convers?es de 86% de CH4 e 91% de CO2 e rendimento de 85% de CO e 81% de H2 para o material Ni/MCM-41_TEOS_C, e convers?es de 82% de CH4 e 87% de CO2 e rendimentos na produ??o do g?s de s?ntese de 70% de CO e 59% de H2 para o material Ni/MCM-41_PV. Esse comportamento semelhante comprova que o TEOS pode ser substitu?do por um material menos nobre
Vankeuren, Jody L. "Parasites Predators and Symbionts." Kent State University / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=kent1619475426952694.
Full textSilva, José Geraldo da, and 69-99903-7010. "Estudo da temperatura de pastas com substituição parcial da silica ativa ao cimento utilizando o método semi-adiabático." Universidade Federal do Amazonas, 2017. https://tede.ufam.edu.br/handle/tede/6541.
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The increasing requests for shorter execution times in concrete using concrete results in a consequent demand for thermal control. This work aims to evaluate the use of silica in the reduction of temperature in cement reactions through tests on cement pastes using device and semi-adiabatic method developed in this research. For that, an equipment and method of use was developed. This work presents a method, including the design of the semi-adiabatic reaction measuring device, with the application of suitable materials to obtain the results, as well as an adequate experimental planning, allowing the evaluation of the active silica as a thermal control proposal. The results showed the different temperature indications, according to the respective dosages of active silica. The dosages of cement were substituted by silica in the proportions of 0, 7, 14 and 20% both with respect to w / c relation of 0.5. The silica was presented increasing or decreasing the temperatures of the reactions according to dosage, aspect, therefore, determinant to the process of application of the same for such purpose according to the data observed.
As crescentes solicitações de menores prazos de execução em projetos utilizando concreto massa traz consequente demanda ao controle térmico. Este trabalho tem o objetivo de avaliar a utilização da sílica na redução da temperatura em reações cimentícias através de ensaios em pastas de cimento empregando dispositivo e método semi-adiabático desenvolvidos nesta pesquisa. Para tanto foi elaborada um equipamento e método de uso. Este trabalho apresenta um método, incluindo o projeto do dispositivo de medição semi-adiabática da reação, contando com a aplicação de materiais adequados a obtenção dos resultados, bem como um planejamento experimental adequado possibilitando obter avaliação da sílica ativa como proposta de controle térmico. Os resultados mostraram as diferentes indicações de temperatura, conforme as respectivas dosagens de sílica ativa. Foram praticadas as dosagens de sílica em substituição ao cimento nas proporções de 0, 7, 14 e 20% ambas com relação a/c de 0,5. A sílica apresentou-se aumentando ou diminuindo as temperaturas das reações conforme dosagem, aspecto, portanto, determinante ao processo de aplicação da mesma para tal finalidade segundo os dados observados.
Hofgård, Daniel, and John Sundkvist. "Climate enhanced concrete in the civil engineering industry." Thesis, KTH, Betongbyggnad, 2020. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-278216.
Full textSveriges regering antog 2017 ett nytt klimatpolitiskt ramverk med målet att Sverige ska ha noll nettoutsläpp av växthusgaser år 2045. Betongindustrin har tagit fram en färdplan för hur betong kan bli klimatneutralt, där ett sätt att reducera klimatpåverkan från betong är att byta ut en del av cementklinkern mot alternativa bindemedel. Mald granulerad masugnsslagg (GGBS), flygaska, silikastoft och trass är alternativa bindemedel som är möjliga att använda i betongblandningar för att reducera mängden Portlandcement. GGBS, flygaska och silikastoft är restprodukter från andra industrier medan trass är en vulkanisk aska som kan utvinnas. Utöver den positiva miljöeffekten som erhålls när alternativa bindemedel ersätter cementklinker, så har de alternativa bindemedlen andra egenskaper, både positiva och negativa, som påverkar betongen. Målet med denna studie var att undersöka och jämföra om betongblandningar där en del av cementklinkern har ersatts med alternativa bindemedel når upp till de krav som ställs i nuvarande regelverk. Utöver det så undersöktes även hur betongblandningarnas materialparametrar påverkades av alternativa bindemedel. Betongblandningarna delades in i tre olika typer av betong: betong för broar (vct 0.4), vattenbyggnader (vct 0.45) och vindkraftverksfundament (vct 0.55), där totalt sju betongblandningar tillverkades i ett laboratorium. Betongblandningarna undersöktes i de tre olika faserna för hårdnande av betong, vilka är färsk, ung och hårdnad betong. De materialparametrar som analyserades var tryckhållfasthet, krympning, frostresistens, arbetbarhet, luftporhalt och temperaturutveckling. Förutom de experimentella testerna gjordes en jämförelse kring hur mycket koldioxid som kan reduceras för varje betongblandning, jämfört med en referensbetong för varje användningsområde. Betongblandningen med ett CEM II/A-V flygaska-cement och 15% GGBS visade stor potential med avseende på de olika materialparametrarna. Denna blandning är dock enligt svensk standard inte möjlig att certifiera för betongbyggnad i exponeringsklass XF4, exempelvis broar, men kan certifieras för betongbyggnad i exponeringsklass XF3, exempelvis fundament för vindkraftverk. Blandningen med 30% GGBS och 5% silikastoft visade även positiva egenskaper, men flyttillsatsmedel måste användas i denna blandning för att erhålla en god arbetbarhet. För vattenbyggnadsbetong så visade blandningen med 35% GGBS en hög tryckhållfasthet, men samtidigt en hög temperaturutveckling och en låg arbetbarhet. Blandningen med trass hade en noterbart låg temperaturutveckling, men med ökad krympning samt låg arbetbarhet. Avslutningsvis så uppvisade alla blandningar en frostresistens som enligt standard klassificeras som ”Mycket bra”.
Moscoso, Ramírez Pedro Antonio. "Aproximaciones a una estrategia integrada para el control no contaminante de las podredumbres verde y azul en poscosecha de cítricos." Doctoral thesis, Universitat Politècnica de València, 2013. http://hdl.handle.net/10251/34626.
Full textMoscoso Ramírez, PA. (2013). Aproximaciones a una estrategia integrada para el control no contaminante de las podredumbres verde y azul en poscosecha de cítricos [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/34626
TESIS
Jin, Yawei. "Simulation methodology to compare emerging technologies for alternatives to silicon gigascale logic device." 2006. http://www.lib.ncsu.edu/theses/available/etd-09192006-231837/unrestricted/etd.pdf.
Full text"Electrical and Thermal Transport in Alternative Device Technologies." Master's thesis, 2013. http://hdl.handle.net/2286/R.I.20942.
Full textDissertation/Thesis
M.S. Electrical Engineering 2013