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Verhagen, Franciscus Johannes Josephus. "Toxicology of the food additives BHA and BHT." Maastricht : Maastricht : Universitaire Pers Maastricht ; University Library, Maastricht University [Host], 1989. http://arno.unimaas.nl/show.cgi?fid=5479.
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Wiginton, John Franklin. "Instrumental laboratories based on the analysis of butylated hydroxytoluene (BHT) and butylated hydroxyanisole (BHA) /." Full text available from ProQuest UM Digital Dissertations, 2008. http://0-proquest.umi.com.umiss.lib.olemiss.edu/pqdweb?index=0&did=1850457291&SrchMode=1&sid=1&Fmt=2&VInst=PROD&VType=PQD&RQT=309&VName=PQD&TS=1279301048&clientId=22256.
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Tran, Amy V. "Do BHA and BHT Induce Morphological Changes and DNA Double-Strand Breaks in Schizosaccharomyces pombe?" Scholarship @ Claremont, 2013. http://scholarship.claremont.edu/scripps_theses/152.
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Butylated Hydroxyanisole, BHA, and Butylated Hydroxytoluene, BHT, are commonly used as preservatives for our food as well as additives in many products such as cosmetics, petroleum, and medicine. Although their use has been approved by the Food and Drug Administration (FDA), there have been controversies and debates on whether these phenol derivatives or antioxidants are safe to use. Their accumulative toxicology and side effects need to be thoroughly investigated as we continue to consume them on a daily basis. Data obtained by genomic analysis in Tang lab suggested the involvement of DNA damage checkpoint/repair pathways in the response network to these phenol stress factors. The aims of this thesis are to examine the morphological changes and potential DNA damage induced by exposing cells to BHA and BHT using fission yeast Schizosaccharomyces pombe as a model organism. Fluorescence microscopy was used to assess DNA double-strain breaks (DSBs) by monitoring the nuclear foci formation of Rad22, a DNA repair protein, in the presence of BHA and BHT. Changes in cell morphology were also studied under microscope. Preliminary data showed that cells treated with BHA and BHT exhibited morphological changes. In addition, for the first time in S. pombe cells, Rad22 foci in the nucleus of BHA and BHT treated cells were observed. Further investigation is needed to optimal the experimental condition to continue the study. These results will not only help us to better understand the effect of these phenol derivatives in the cells, but can also establish an experimental system for future studies on the interaction of the cells with stress factors and therapeutic drugs for human-related diseases such as cancer.
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Borges, Ãngela da Silva. "Uso de compostos extraÃdos da manga (Mangifera indicus) no controle da oxidaÃÃo lipÃdica na carne de frango, em produto cÃrneo tipo mortadela e ovos de consumo." Universidade Federal do CearÃ, 2009. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=6057.
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FundaÃÃo Cearense de Apoio ao Desenvolvimento Cientifico e TecnolÃgicoO presente trabalho teve como objetivos avaliar o efeito da inclusÃo de antioxidantes naturais da manga na raÃÃo de frangos de corte e de poedeiras comerciais sobre a estabilidade oxidativa da carne de frango, produto cÃrneo tipo mortadela, bem como dos ovos de consumo. Foram preparados dois extratos etanÃlicos com a casca (E1) e o caroÃo (E2) da manga. Os extratos desidratados foram utilizados em dois ensaios biolÃgicos: um com frangos de corte e outro com poedeiras comercias. Em ambos os ensaios os tratamentos alimentares das aves consistiram no controle, T1, raÃÃo sem adiÃÃo de extratos; T2 raÃÃo com adiÃÃo de 200ppm de butilato de hidroxitolueno (BHT); T3 e T4, raÃÃes com 200 e 400ppm de extrato da casca da manga, respectivamente; e T5 e T6, raÃÃes com 200 e 400ppm de extrato do caroÃo da manga, respectivamente. No ensaio com frangos foram utilizados 360 pintos de um dia, da linhagem Ross, distribuÃdos ao acaso entre os seis tratamentos com seis repetiÃÃes de 10 aves. No ensaio com poedeiras foram utilizadas 180 aves da linhagem Hisex x Whitw, com 40 semanas de idade, distribuÃdas ao acaso entre os seis tratamentos com cinco repetiÃÃes de seis aves. A carne dos frangos de corte foi utilizada para os Experimentos 1 e 2 e os ovos das poedeiras para o Experimento 3. No Experimento 1, quatro aves com 42 dias de idade, foram selecionadas e apÃs o abate, foram coletados os peitos desossados, divididos ao meio e embalados a vÃcuo. Os peitos esquerdos foram armazenados em refrigeraÃÃo (4ÂC) e os peitos direitos em congelamento (-20ÂC). Foram realizadas anÃlises de cor e da oxidaÃÃo lipÃdica da carne nos tempos 0, 5, 10 e 15 dias, nas amostras refrigeradas, e nos tempos 0, 30, 60 e 90 dias nas amostras congeladas. No Experimento 2, foram utilizados os mesmos frangos do Experimento 1, sendo que os cortes da coxa e sobre coxa foram coletados e apÃs a desossa e retirada da pele a carne foi utilizada na formulaÃÃo de mortadelas que foram armazenadas em refrigeraÃÃo (4C) por 90 dias. Durante o armazenamento foram realizadas anÃlises de cor e estabilidade lipÃdica (TBARS) do produto cÃrneo com 0, 30, 60 e 90 dias. No Experimento 3, foram selecionados 25 ovos de cada repetiÃÃo os quais foram armazenados em refrigeraÃÃo (4C) e as anÃlises da cor (leque colorimÃtrico e sistema CIE Lab) e da oxidaÃÃo lipÃdica da gema realizadas nos tempos 0, 15, 30, 45 e 60 dias. No Experimento 1, foi observada uma reduÃÃo dos valores do componente de cor L* (luminosidade) durante o armazenamento da carne de peito de frango em congelamento, e um aumento do componente a* (intensidade de vermelho) durante o armazenamento em refrigeraÃÃo. Os valores de TBARS sofreram aumento considerÃvel na carne de peito proveniente de todos os tratamentos durante o armazenamento sob refrigeraÃÃo e sob congelamento. Comparando com o tratamento controle (T1), os tratamentos contendo BHT ou os extratos E1 e E2 nas concentraÃÃes de 200 e 400 ppm (T2, T3, T4, T5 e T6) foram eficientes no controle da oxidaÃÃo lipÃdica da carne do peito de frango em refrigeraÃÃo por 5 dias ou em congelamento por 3 meses. No Experimento 2, de uma forma geral o armazenamento das mortadelas por 90 dias provocou reduÃÃo nos valores do componente de cor L* e aumentos nos valores dos componentes de cor a* e b*. Os produtos formulados com a carne proveniente de frangos em todos os tratamentos sofreram aumentos nos valores de TBARS com o tempo de armazenamento. Durante a estocagem em refrigeraÃÃo os tratamentos T2 e T6 foram os mais eficientes no controle da oxidaÃÃo lipÃdica nas mortadelas. No experimento 3, nÃo houve variaÃÃo significativa do componente de cor L* na gema dos ovos provenientes dos tratamentos alimentares T2, T3, T4, T5 e T6, em relaÃÃo ao tratamento controle (T1), durante todo o perÃodo de armazenamento. Os valores do componente de cor a* sofreram aumentos com o tempo de armazenamento em todos os tratamentos, enquanto que para os valores do componente de cor b* nÃo houve diferenÃa significativa entre os tratamentos. Quanto à cor medida pelo leque colorimÃtrico, os tratamentos nÃo tiveram efeito significativo em relaÃÃo ao tratamento controle (T1), ao longo de todo o perÃodo de armazenamento. A oxidaÃÃo lipÃdica da gema dos ovos dos tratamentos com adiÃÃo de antioxidante (T2, T3, T4, T5 e T6) foi menor que a dos ovos do tratamento controle (T1), mas aumentou durante o armazenamento dos ovos. Os ovos do T5 apresentaram a menor taxa de aumento da oxidaÃÃo lipÃdica ao final do perÃodo de armazenamento, seguido daqueles dos tratamentos T4 e T6, respectivamente. Pode ser concluÃdo que os extratos da casca e do caroÃo da manga podem ser usados na alimentaÃÃo das aves para ajudar no controle da oxidaÃÃo lipÃdica dos produtos avÃcolas carne e ovos.
The present study aimed to evaluate the effects of addition of natural antioxidants from mango in the feed of the broiler chickens and laying hens on the oxidative stability of chicken meat, a product processed from this meat (chicken mortadella) and eggs for consumption. It was prepared two ethanolic extracts from the peel (E1) and (E2) mango seed. The dried extracts were used in two bioassays, one with chickens and one with laying hens. In both trials, the alimentary treatments consisted in control, T1, feed without addition of extracts, T2, feed with addition of 200 ppm of butylated hydroxytoluene (BHT), T3 and T4, feed with 200 and 400ppm of extract of the mango peel, respectively, and T5 and T6, feed with 200 and 400ppm extract of the mango seed, respectively. In the trial with chickens, 360 chicks in a day, from Ross line were used, which were distributed randomly among the six treatments with six replicates of 10 poultry. In the trial with laying hens, 180 poultry from Hisex x Whitwam line, with 40 weeks of age were used, which were randomly distributed among six treatments with five replicates of six poultry. The meat of the broiler chickens was used for the Experiments 1 and 2 and the eggs of the laying hens for the Experiment 3. In Experiment 1, four poultry with 42 days of age, were selected and after slaughter, the boneless breasts were collected, split in half and vacuum packed. The samples of left breasts were stored under refrigeration (4 oC) and the rights breasts under freezing (~20 oC). The analyses of color and lipid oxidation of the meat were performed at 0, 5, 10 and 15 days in the refrigerated samples, and at 0, 30, 60 and 90 days in the frozen samples. In Experiment 2, the same chickens from Experiment 1 were used, whose the sections of the leg and thigh were collected and after boning and skinning the meat was used in the formulation of mortadella which were stored under refrigeration (4 oC) for 90 days. During the storage of meat product were carried out color (CIE Lab system) and lipid stability (TBARS) analysis at 0, 30, 60 and 90 days. In Experiment 3, it was selected 25 eggs from each replicate which were stored under refrigeration (4 oC) and analysis of color (color fan and the CIE Lab) and lipid oxidation (TBARS) of yolk were realized at 0, 15 , 30, 45 and 60 days. In Experiment 1, it was observed a reduction of L * values (brightness) in chicken breast during storage under freezing, and an increase in a* value (redness) during storage under refrigeration. The values of TBARS suffered considerable increase in all treatments during storage under refrigeration or freezing. Compared with the control treatment (T1), treatments containing BHT (T2) or extracts E1 and E2 at concentrations of 200 and 400 ppm (T3, T4, T5 and T6) were effective in controlling lipid oxidation of breast meat chicken chilled for 5 days or frozen for 3 months. In Experiment 2, the storage of the mortadella for 90 days resulted in reduction of the L* value and increases of the a* and b* values. The chicken meat products in all treatments had elevated values of TBARS with increase in storage time. During storage under refrigeration, T2 and T6 treatments were the most effective in controlling lipid oxidation in mortadella. In experiment 3, there was no significant variation in the color component L * of the eggs yolk from the T2, T3, T4, T5 and T6 treatments compared to the control treatment (T1), throughout the storage period. The a* values was increased with the storage time for all treatments, while for the b* values there was no significant difference between treatments. In relation to the color measured by yolk color fan, the treatments had no significant effect in comparison to control treatment (T1), throughout the storage period. The lipid oxidation of egg yolk from added-antioxidant treatments (T2, T3, T4, T5 and T6) was smaller than the eggs from the control treatment (T1), but increased during storage of eggs. The eggs from T5 treatment had the lowest rate of increase in lipid oxidation at the end of the storage period, followed by those of T4 and T6 treatments, respectively. It was concluded that the extracts of peels and seed of mango can be used in poultry feed to help control lipid oxidation poultry products and eggs.
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Häner, Robert. "Erzeugung von Ketenen aus BHT-Esterenolaten sowie Metallierung von Cyclopropan- und Aziridin-2-carbonsäurederivaten /." [S.l.] : [s.n.], 1987. http://e-collection.ethbib.ethz.ch/show?type=diss&nr=8265.
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Kertzscher, Jana. "2. Freiberger Kolloquium Elektrische Antriebstechnik: Kolloquium im Rahmen des 70. BHT - Freiberger Universitätsforum 2019." Technische Universität Bergakademie Freiberg, 2019. https://tubaf.qucosa.de/id/qucosa%3A38447.
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Vom 6.6. bis 7.6.2019 fand das 2. Freiberger Kolloquium Elektrische Antriebstechnik (FKEA) im Rahmen des 70. BHT statt. Schwerpunkte sind die Modellierung und Simulation von elektrischen Maschinen, thermische Untersuchungen, Auslegung und Fertigung neuer Motorenkonzepte sowie Traktionsspeicher.
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Kertzscher, Jana. "3. Freiberger Kolloquium Elektrische Antriebstechnik: Kolloquium im Rahmen des 72. BHT - Freiberger Universitätsforum 2021." Technische Universität Bergakademie Freiberg, 2021. https://tubaf.qucosa.de/id/qucosa%3A75538.
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Dieser Konferenzband stellt alle schriftlich eingereichten Beiträge zum 3. Freiberger Kolloquium Elektrische Antriebstechnik zusammen. Thematische Schwerpunkte waren 2021: Modellierung und Simulation von elektrischen Maschinen und Antrieben, Auslegung und Fertigung neuer Motorenkonzepte, Thermische Untersuchungen an elektrischen Maschinen, Regelung elektrischer Maschinen, Ladetechnologien für Elektrofahrzeuge, Theoretische Elektrodynamik von Traktionsantrieben
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Martins, Marli Cardoso. "Resposta cardiovascular a noradrenalina e ao BHT-920 em ratos submetidos aos "stress" por natação." [s.n.], 1991. http://repositorio.unicamp.br/jspui/handle/REPOSIP/314612.
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Orientador: Regina Celia SpadariDissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Biologia
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Resumo: Estudos prévios demonstraram que átrios direitos isolados de ratos submetidos ao "stress" apresentam alterações de sensibilidade ao efeito cronotrópico das catecolaminas. Os objetivos deste trabalho são: avaliar a possibilidade de uitilização da técnica de registro da pressão arterial em ratos não anestesiados, para a análise das respostas cronotrópica e pressórica às catecolaminas; descrever as alterações de sensibilidade cardiovascular às catecolaminas em ratos submetidos ao "stress"; caracterizar a participação dos diferentes tipos de adrenoceptores nestas alterações; comparar as alterações observadas "in vivo" com aquelas anteriormente descritas em átrios direitos isolados de ratos submetidos ao "stress". Utilizamos ratos machos, adultos, Wistar. Sob anestesia por éter, as artérias e veias femurais esquerdas de cada animal foram canuladas 24s antes do experimento. O registro da pressão arterial foi obtido conectando-se a cânula arterial a um transdutor de pressão, enquanto o animal permanecia em sua própria gaiola, não anestesiado. A administração dos diferentes farmacos foi realizada através da cânula venosa. Os animais do grupo experimental foram submetidos a 50 min. de natação... O resumo, na íntegra, poderá ser visualizado no texto completo da tese digital
Abstract: Not informed.
Mestrado
Fisiologia
Mestre em Ciências Biológicas
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Araujo, Endrigo Adonis Braga de [UNESP]. "Efeito da adição de butil-hidroxitolueno nos meios de refrigeração e congelação sobre a viabilidade espermática de equinos." Universidade Estadual Paulista (UNESP), 2016. http://hdl.handle.net/11449/138123.
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Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)
O processo de criopreservação acarreta estresse oxidativo à célula espermática e a adição de antioxidantes aos meios de refrigeração e congelação de sêmen pode auxiliar na proteção dos espermatozoides contra o dano induzido pelas espécies reativas de oxigênio (ERO), incluindo perda da motilidade de forma irreversível, peroxidação lipídica e fragmentação do DNA, interferindo na capacidade de fertilização do espermatozoide. Dentre os diferentes antioxidantes, o Butil-hidroxitolueno (BHT) é um análogo sintético da vitamina E, cujo efeito protetor é atribuído a dois mecanismos: o aumento da fluidez da membrana plasmática após a incorporação do antioxidante, e o segundo por conter a cascata de peroxidação lipídica pela conversão de peroxil em hidroperóxido lipídico. O BHT foi testado em diversas espécies demonstrando melhora na motilidade, integridade de membrana plasmática e viabilidade espermática; porém, na espécie equina, a inclusão de BHT em diluentes para criopreservação de sêmen necessita ser melhor avaliada. Deste modo, o objetivo deste trabalho foi avaliar a influência do BHT nas células espermáticas de equinos submetidas à criopreservação e sua capacidade de conter a peroxidação lipídica e produção de espécies reativas de oxigênio quando os espermatozoides foram submetidos a estresse.
The process of cryopreservation brings out oxidative stress to spermatic cell and the addition antioxidant of into cooling and freezing semen extenders could assist in protection of spermatozoa against the damage induced by reactive oxygen species (ROS), including irreversible loss in motility, lipid peroxidation and DNA fragmentation, interfering with the fertilizing capacity of sperm. Among different antioxidants, the butylated hydroxytoluene (BHT) is a synthetic analogue of vitamin E, whose protective effect is attributed to two mechanisms: the increase in sperm membrane fluidity after the addition of antioxidant, and the lipid peroxidation cascade for converting peroxy radicals into lipid hydroperoxides. BHT was tested in different species and the results include improvement in motility, spermatic membrane integrity and sperm viability. However, the addition of BHT in horse semen extenders for cryopreservation purposes demands further research. Thereby, the aims of this study were (1) to evaluate the influence of BHT on equine spermatic cells submitted to cryopreservation and (2) the capacity of BHT to contain the lipid peroxidation and the production of reactive species of oxygen when sperm cells were submitted to stress.
FAPESP: 2014/00175-8
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Araujo, Endrigo Adonis Braga de. "Efeito da adição de butil-hidroxitolueno nos meios de refrigeração e congelação sobre a viabilidade espermática de equinos." Botucatu, 2016. http://hdl.handle.net/11449/138123.
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Orientador: Frederico Ozanam PapaResumo: O processo de criopreservação acarreta estresse oxidativo à célula espermática e a adição de antioxidantes aos meios de refrigeração e congelação de sêmen pode auxiliar na proteção dos espermatozoides contra o dano induzido pelas espécies reativas de oxigênio (ERO), incluindo perda da motilidade de forma irreversível, peroxidação lipídica e fragmentação do DNA, interferindo na capacidade de fertilização do espermatozoide. Dentre os diferentes antioxidantes, o Butil-hidroxitolueno (BHT) é um análogo sintético da vitamina E, cujo efeito protetor é atribuído a dois mecanismos: o aumento da fluidez da membrana plasmática após a incorporação do antioxidante, e o segundo por conter a cascata de peroxidação lipídica pela conversão de peroxil em hidroperóxido lipídico. O BHT foi testado em diversas espécies demonstrando melhora na motilidade, integridade de membrana plasmática e viabilidade espermática; porém, na espécie equina, a inclusão de BHT em diluentes para criopreservação de sêmen necessita ser melhor avaliada. Deste modo, o objetivo deste trabalho foi avaliar a influência do BHT nas células espermáticas de equinos submetidas à criopreservação e sua capacidade de conter a peroxidação lipídica e produção de espécies reativas de oxigênio quando os espermatozoides foram submetidos a estresse.
Abstract: The process of cryopreservation brings out oxidative stress to spermatic cell and the addition antioxidant of into cooling and freezing semen extenders could assist in protection of spermatozoa against the damage induced by reactive oxygen species (ROS), including irreversible loss in motility, lipid peroxidation and DNA fragmentation, interfering with the fertilizing capacity of sperm. Among different antioxidants, the butylated hydroxytoluene (BHT) is a synthetic analogue of vitamin E, whose protective effect is attributed to two mechanisms: the increase in sperm membrane fluidity after the addition of antioxidant, and the lipid peroxidation cascade for converting peroxy radicals into lipid hydroperoxides. BHT was tested in different species and the results include improvement in motility, spermatic membrane integrity and sperm viability. However, the addition of BHT in horse semen extenders for cryopreservation purposes demands further research. Thereby, the aims of this study were (1) to evaluate the influence of BHT on equine spermatic cells submitted to cryopreservation and (2) the capacity of BHT to contain the lipid peroxidation and the production of reactive species of oxygen when sperm cells were submitted to stress.
Mestre
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Kertzscher, Jana. "Freiberger Kolloquium Elektrische Antriebstechnik: 68. BHT - Freiberger Universitätsforum : Herrn Prof. Dr.-Ing. habil. Ulrich Beckert zum 75. Geburtstag gewidmet." Technische Universität Bergakademie Freiberg, 2017. https://tubaf.qucosa.de/id/qucosa%3A36174.
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Vom 8.6. bis 9.6.2017 fand im Rahmen des BHT das Fachkolloquium Elektrische Antriebstechnik statt. Das Freiherger Kolloquium Elektrische Antriebstechnik umfasst den Themenkreis elektrische Maschinen, elektrische Antriebe und Energiespeicher. Dabei sind Modellierung und Simulation von elektrischen Maschinen und Antrieben, Auslegung neuer Motorenkonzepte, thermische Untersuchungen an elektrischen Maschinen und Alterung der Energiespeicher die thematischen Schwerpunkte der Veranstaltung.
Der Kolloquiumsband ist Herrn Prof. Dr.-Ing. habil. Ulrich Beckert zu semem 75. Geburtstag gewidmet.
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Gregg, Alison Dianne. "The design and synthesis of potential dual action cardioprotective agents acting at adenosine receptors." Queensland University of Technology, 2006. http://eprints.qut.edu.au/16629/.
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Adenosine and adenosine analogues are recognised as cardioprotective agents due to the responses that they induce through the activation of myocardial adenosine receptors. Antioxidants such as nitroxide radicals have also been found to possess cardioprotective properties in biological systems, namely through their ability to scavenge the oxygen-based free radicals that are potentially damaging to tissues and cells. It was envisaged that the linking of an antioxidant moiety to adenosine would produce an adenosine analogue that activates adenosine receptors and also scavenges oxygen-derived free radicals in the body. Consequently, one aim of this project was to synthesise a series of adenosine analogues that possessed a nitroxide or a phenolic antioxidant at the N6 position of the adenosine skeleton.
Allosteric ligands have several advantages over orthosteric ligands as potential therapeutic agents, and research into the allosteric enhancement of adenosine receptors is a burgeoning field. It was envisaged that the linking of an antioxidant moiety to an allosteric enhancer would produce a compound that enhances the response of endogenous activation of adenosine receptors and also scavenges oxygen-based free radicals in the body. Consequently, a second aim of this project was to synthesise a series of allosteric enhancers of the A1 adenosine receptor that possessed antioxidant capability endowed by a nitroxide or a phenolic antioxidant functionality.
This project has resulted in the synthesis and characterisation of 19 novel N6 substituted adenosine analogues, and additionally 12 novel derivatised thiophenes. Each of the target compounds was tested for its ability to bind to each of the adenosine receptor subtypes and some analogues were found to be potent and selective adenosine receptor agonists.
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Maxwell, Sheena, and sheenamax@optusnet com au. "An assesssment of non-conventional measures of lung function and the effedt of a herbal extract on mild-moderate childhood asthma." RMIT University. Health Sciences, 2007. http://adt.lib.rmit.edu.au/adt/public/adt-VIT20080507.150547.
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Background: Respiratory conditions are prevalent and cause an enormous burden on society. In recent decades, there has been a global increase in asthma in children and adults, yet the diagnosis of asthma must be made on clinical grounds as the diagnostic use of pharmacological reversibility of airway obstruction remains controversial. It is possible however that tools exist from different medical paradigms that may assist in the clinical diagnosis of asthma. Tools such as Traditional Chinese Medicine (TCM) enquiry, Breath Holding Time (BHT) or Electro-Dermal Screening Test (EDST) may provide useful clinical information, yet their use has not been widely explored or validated. Integrative medicine may be considered to represent a new frontier in medicine where each therapy and diagnostic method is seen to have its own advantages and limitations and where an integration of both diagnostic and therapeutic techniques from conventional and complementary medicine is seen to produce the best results. However, while there is a high community use of complementary therapies for conditions such as asthma, there is also a need to maintain accepted standards of medical and scientific principles and foster high quality research into complementary therapies. Objectives: The current study sought to determine: If there is a correlation between conventional measures of lung function such as Forced Expiratory Volume in one second (FEV1) and less conventional measures such as airways expired NO level (eNO), electrodermal measures, TCM enquiry and BHT. If any of the lung function measures are able to distinguish between asthmatic and healthy subjects. If the use of a rye grass extract is better than placebo in improving requirements for bronchodilator medication, peak flow, forced expiratory volume in one second or quality of life in mild to moderate childhood asthma. Rational for carrying out two separate studies as one study; The author was interested on both the integration of diagnostic techniques as well as the effect of the herbal extract on asthma so it was decided to use the opportunity and put both in one study. Method: A range of conventional and non-conventional measures were conducted in healthy and asthmatic children including demographic details, quality of life data, spirometry measures, airway nitric oxide levels, electro-dermal measures, TCM history enquiries, breath holding time, and skin prick tests. The data were analysed to determine any significant correlations between these measures. A double blind randomized controlled pilot clinical trial was also performed to assess the effect of using rye grass extract in asthmatic children aged 8 to 16 years. Results: There were significant correlations between forced expiratory volume in one second and active quality of life, TCM spleen score and fraction of exhaled nitric oxide measurements. There were also statistically significant differences between asthmatic and healthy subjects in TCM history, breath holding time and exhaled nitric oxide. The use of rye grass extract did not produce any significant improvement over placebo in any of the asthma outcome measures. Conclusions: The use of inexpensive measures such as BHT and TCM enquiry may provide useful clinical information when assessing respiratory conditions such as asthma. However, further research is required in larger populations to confirm their use. The use of the rye grass extract at the dose given in this study did not provide any clinical benefit for the asthmatic children in this study.
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Iglebaek, Herceglija Ena. "Stability testing of all-trans-retinol in an experimental cosmetic formulation and in methanol and methanol containing butylhydroxytoluene (BHT) using reversed-phase HPLC." Thesis, KTH, Kemi, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-302695.
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All-trans-retinol (vitamin A) används ofta som en aktiv ingrediens i kosmetiska produkter på grund av dess kliniskt validerade anti-age-egenskaper. Däremot är användningen av all-trans-retinol i kosmetiska formuleringar begränsad till följd av den kemiska stabiliteten av all-trans-retinol som påverkas av värme, syre, ljus och syror. Både kompositionen av en kosmetisk formulering, samt lagringsförhållanden och förpackningen av produkten, kan påverka nedbrytningen av all-trans-retinol till mindre aktiva former. I denna studie har stabilitetstestning genomförts under två månader i syfte att utvärdera inverkan som lagringstemperatur (21°C och 5°C) och produktförpackning (en luftfri behållare och en burk) kan ha på nedbrytningen av all-trans-retinol i en experimentell oljegel. All-trans-retinol extraherades med metanol innehållande 0.5 mg/mL butylhydroxytoluen (BHT) och analyserades med reversed-phase HPLC med 1% ammoniumacetat och metanol (12:88, v/v) som mobilfas. I HPLC-kromatogrammen upptäcktes en okänd nedbrytningsprodukt, vilket möjliggjorde stabilitetstestning av all-trans¬-retinol genom att undersöka förändringar i förhållandet mellan nedbrytningsprodukten och all-trans-retinol. Stabilitetstestningen av de experimentella oljegelerna resulterade i mindre än 4% nedbrytningsprodukt i förhållande till mängden all-trans-retinol efter 56 dagars lagring, oberoende av produktförpackning och lagringstemperatur, med den förslagna analysmetoden. Studien visade också att instabiliteten hos extraherad all-trans-retinol har en dominerande inverkan på resultaten som kan leda till en överskattning av nedbrytningsprodukten på grund av temperaturen under beredning och lagring av förberedda prover. Dessutom utvärderades stabiliteten av all-trans-retinol i metanol och metanol innehållande 0,5 mg/ml butylhydroxytoluen (BHT). Upp till 6% nedbrytning av all-trans-retinol i metanol med BHT kan förväntas om beredda proverna lagras i rumstemperatur, medan mindre än 1% nedbrytningsprodukt detekterades i prover som bevaras kylda under analysen. Av denna anledning har det föreslagits att förhållandena vid beredning, hantering och lagring av extraherad all-trans-retinol bör kontrolleras för att förhindra inverkan från omgivningen, såsom temperatur, ljus och syre.All-trans-retinol, or vitamin A, is frequently used as an active ingredient in cosmetic products because of its clinically validated anti-aging properties. The use of all-trans-retinol in cosmetic formulations is limited by its susceptibility to heat, oxygen, light, and acids. In a cosmetic product, the composition, as well as the storage conditions and the type of packaging, may influence the degradation of all-trans-retinol into less active forms. In this study, long-term stability testing was conducted with the purpose to evaluate the effect that storage temperature (21°C and 5°C) and product packaging (an airless container and a jar) may have on the degradation of all-trans-retinol in an experimental oil-gel during a 2-months period. All-trans-retinol was extracted with methanol containing 0.5 mg/mL butylhydroxytoluene (BHT) and was analysed with a reversed-phase HPLC system, using 1% ammonium acetate and methanol (12:88) as the solvent system. The HPLC chromatograms revealed an unknown degradation product, allowing stability testing of all-trans-retinol by detecting variations in the ratio between the degradation product and all-trans-retinol. The stability testing of the experimental oil-gels resulted in less than 4% degradation product in relation to all-trans-retinol after 56 days of storage, independent of the product packaging and storage temperature, with the proposed analytical method. It was also shown that the instability of extracted all-trans-retinol will have a predominant impact on the results causing an overestimation of the degradation product because of the temperature during sample preparation and storage. In addition, the stability of all-trans-retinol in methanol and methanol containing 0.5 mg/mL butylhydroxytoluene (BHT) was evaluated. It was concluded that up to 6% degradation of all-trans-retinol in methanol with BHT can be expected if prepared samples are stored in room temperature, while less than 1% degradation product will be present if prepared samples are kept cold during analysis. It has been proposed that the conditions during preparation, handling, and storage of extracted all-trans-retinol should be controlled to prevent interference of external conditions, such as temperature, light, and oxygen.
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Reed, Gail L. "Fast GC: Applications and Theoretical Studies." Diss., Virginia Tech, 1999. http://hdl.handle.net/10919/29085.
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Experimental data are presented for the first time in support of a theoretical model of band broadening proposed by Blumberg (1997). This model addresses the effects of the compressibility of the mobile phase in gas chromatography and presents an equation derived from only two mutually independent variables. Solutions of decane and tridecane in hexane were analyzed at pressures ranging from 15 to 150 psi. Six different columns were used that varied in length, internal diameter and film thickness. Theoretical plate heights were obtained from this data and plotted versus the average linear carrier gas velocity (Golay type plots). These plots showed that at high pressures the Blumberg model fit the experimental data statistically significantly better than the earlier model proposed by Golay. The Blumberg model also accurately predicts the relationship between the optimum linear carrier gas velocity and the temperature.
The second part of this work explores the scope and limitations of fast temperature programming in the fast GC analyses of various sample types. These samples included polycyclic aromatic hydrocarbons (PAHs), hydrocarbons and food samples. Programming rates of up to 1200° C/min were used. These fast programming rates were obtained by using "flash"⠢ temperature programming, controlled by resistive heating of a metal tube that enclosed a capillary column. The precision of peak data was found to be good, less than 5% for peak areas and 4% for retention times. However, a slight, but statistically significant decrease in peak areas was seen above programming rates of 240° C/min.
Microwave assisted extraction (MAE) was used to extract 2,6-di-(tert-butyl)-4-methylphenol, BHT, from chewing gum and breakfast cereal. The extraction was followed by a fast GC analysis (less than 4 minutes) using "flash"â ¢ temperature programming. MAE reduced the sample preparation time, from hours to minutes, and consequently reduced, the total analysis time. Extraction times longer than 5 minutes gave decreased recoveries of BHT.Ph. D.
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Romano, Dario. "Influence of catalytic systems on the synthesis of (dis)entangled UHMWPE and its implications on mechanical properties." Thesis, Loughborough University, 2014. https://dspace.lboro.ac.uk/2134/14446.
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Two different catalysts (bis[N-(3-tert-butylsalicylidene)-pentafluoroanilinato] titanium (IV) dichloride and [1-(8-quinolyl)indenyl] chromium (III) dichloride catalysts) activated with aluminoxane based co-catalysts (MAO, PMAO, MMAO12 and MMAO3A) have been evaluated in the polymerisation of ethylene leading to UHMWPE having a reduced number of entanglements between the chains. The effect of a co-catalyst modifier (BHT) on the catalytic systems and the resulting polymers is also addressed. Both catalysts are capable to promote the synthesis of UHMWPE having a reduced amount of entanglements in the conditions used. Uniaxial solid-state deformation of UHMWPE samples of different molar masses have been evaluated and related with the entanglement state of the polymers synthesised. A clear relationship between some mechanical properties and the molar mass/entanglement density of the polymers synthesised has been found.
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Santos, Francisco Francielle Pinheiro dos. "AvaliaÃÃo de antioxidantes aplicados à produÃÃo de biodiesel." Universidade Federal do CearÃ, 2013. http://www.teses.ufc.br/tde_busca/arquivo.php?codArquivo=10400.
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CoordenaÃÃo de AperfeiÃoamento de Pessoal de NÃvel SuperiorEste trabalho apresenta um estudo do comportamento e eficÃcia de antioxidantes aditivados ao biodiesel do Ãleo de soja. Os antioxidantes mais utilizados sÃo de estrutura fenÃlica, deste modo, sintetizar, comparar e estudar a aÃÃo destes antioxidantes avaliando as possÃveis causas que os levam a serem mais eficazes traz-nos informaÃÃes para a sÃntese de compostos com melhor atuaÃÃo antioxidante. Para uso como substrato orgÃnico, foi sintetizado o biodiesel a partir do Ãleo de soja, uma vez que à a partir deste, a produÃÃo de 81 % do biodiesel produzido no Brasil. Outro fator para o uso do Ãleo de soja à que este possui majoritariamente em sua composiÃÃo Ãcido linolÃico e olÃico, Ãcidos insaturados, altamente suscetÃveis à oxidaÃÃo. O biodiesel foi sintetizado atravÃs da reaÃÃo de transesterificaÃÃo com Ãlcool metÃlico, razÃo molar Ãlcool/Ãleo de 1:6 e hidrÃxido de sÃdio 0,5 % (m/m). As amostras de biodiesel foram aditivadas com os antioxidantes comerciais (BHT e ionol) e da biomassa (cardanol hidrogenado e cardanol alquilado) nas concentraÃÃes de 300, 600, 900, 1200, 1500, 2000, 3000 e 4000 mg/kg e armazenadas em frasco Ãmbar em uma temperatura de 22,  3 ÂC. Todas as amostras foram analisadas em teste de oxidaÃÃo acelerada (Rancimat), no tempo zero (momento logo apÃs a aditivaÃÃo) e apÃs 2, 4, 6, 9 e 12 meses de armazenamento. Durante o monitoramento observou-se a variaÃÃo do tempo de induÃÃo via rancimat em funÃÃo do tempo de armazenamento das amostras. As anÃlises tÃrmicas foram realizadas com o biodiesel do Ãleo de soja, BHT, ionol, cardanol hidrogenado, cardanol alquilado, e do biodiesel aditivado com estes antioxidantes nas concentraÃÃes de 300, 900, 1500, 3000 e 4000 mg/kg, na taxa de aquecimento de 10 ÂC/min, em atmosfera de nitrogÃnio, com faixa de aquecimento de 30 ÂC â 600 ÂC. AtravÃs da anÃlise tÃrmica verificaram-se o comportamento das amostras quando submetidas a temperaturas elevadas. As anÃlises por UV-vis foram realizadas com o intuito de avaliar o processo de autoxidaÃÃo das amostras apÃs 12 meses de armazenamento. Os experimentos via rancimat revelaram que os antioxidantes comerciais sÃo melhores que os da biomassa, os experimentos termogravimÃtricos e via UV-vis auxiliaram na constataÃÃo de que para otimizar antioxidantes fenÃlicos deve-se adicionar substituintes de baixo peso molecular nas posiÃÃes orto e para. AtravÃs dos resultados via Rancimat foi desenvolvido um software para a prediÃÃo do tempo de estabilidade oxidativa em funÃÃo do antioxidante utilizado, quantidade adicionada deste, tempo de armazenamento, bem como, realizar uma anÃlise econÃmica do custo de utilizaÃÃo de cada antioxidante.
This paper presents a study of the behavior and effectiveness of antioxidants additives for biodiesel from soybean oil. The most commonly used antioxidants are ofphenolic structure, thereby synthesizing, examining and comparing the antioxidant action for evaluating possible causes for a structure to be more effective when compared to another, brings forth necessary tools in the search for better performance antioxidant compounds. For use as an organic substrate, it was synthesized biodiesel from soybean oil, since this oil is from producing about 81 % of biodiesel produced in Brazil. Another factor for the use of soybean oil is that it has in its composition mainly oleic and linoleic acids, unsaturated acids highly susceptible to oxidation. The biodiesel was synthesized by the transesterification reaction with methyl alcohol, the molar ratio alcohol / oil of 1:6 and sodium hydroxide 0.5% (m / m). The biodiesel samples were doped with antioxidants (BHT and ionol), and biomass (hydrogenated cardanol and cardanol alkylated) at concentrations of 300, 600, 900, 1200, 1500, 2000, 3000 and 4000 mg.kg-1 and stored in an amber vial at a temperature of 22, Â 3 Â C. All samples were analyzed in an accelerated oxidation test (Rancimat), at the beginning (immediately after the moment additives) and after 2, 4, 6, 9 and 12 months storage. During monitoring the observed variation via Rancimat induction time as a function of storage time of the samples. The thermal analyzes were performed with biodiesel from soybean oil, BHT, ionol, hydrogenated cardanol, cardanolalkylated, and biodiesel doped antioxidants at concentrations of 300, 900, 1500, 3000 and 4000 mg.kg-1 rate heating to 10 Â C / min in a nitrogen atmosphere with heating range of 30 Â C - 600 Â C.Through thermal analysis verified the behavior of the samples when exposed to elevated temperatures. The analysis by UV-vis were conducted in order to evaluate the process of autoxidation of the samples after12 months of storage. The experiments via rancimat revealed that the commercial antioxidants are better than those of biomass, and to the thermogravimetric experiments via UV-vis the finding that helped to optimize phenolic antioxidants should be added low molecular weight substituent at the ortho and para positions. Through the results via Rancimat software was developed to predict the time depending on the oxidative stability of the antioxidant used, this added amount, time of storage and, perform an economic analysis cost of use of each antioxidant.
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Gondim, Amanda Duarte. "Avalia??o da estabilidade t?rmica e oxidativa do biodiesel de algod?o e do efeito da adi??o de antioxidantes (α-tocoferol e BHT)." Universidade Federal do Rio Grande do Norte, 2009. http://repositorio.ufrn.br:8080/jspui/handle/123456789/17703.
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This work aims to study the effects of adding antioxidants, such as, α- tocopherol and BHT on the thermal and oxidative stability of biodiesel from cottonseed (B100). The Biodiesel was obtained through the methylical and ethylical routes. The main physical and chemical properties of cotton seed oil and the B100 were determined and characterized by FTIR and GC. The study of the efficiency of antioxidants, mentioned above, in concentrations of 200, 500, 1000, 1500, 2000ppm, to thermal and oxidative stability, was achieved by Thermogravimetry (TG), Differential Thermal Analysis (DTA), Differential Scanning Calorimetry (DSC), Differential Scanning Calorimetry - Hi-Pressure (P-DSC) and Rancimat. The Biodiesel obtained are within the specifications laid down by Resolution of ANP No7/2008. The results of TG curves show that the addition of both antioxidants, even in the lowest concentration, increases the thermal stability of Biodieseis. Through the DTA and DSC it was possible to study the physical and chemical transitions occurred in the process of volatilization and decomposition of the material under study. The initial time (OT) and temperature (Tp) of oxidation were determined through the P-DSC curve and they showed that the α-tocopherol has a pro-oxidant behavior for some high concentrations. The BHT showed better results than the α-tocopherol, with regard to the resistance to oxidation
Este trabalho tem como objetivo estudar o efeito da adi??o de agentes antioxidantes, tais como o α-tocoferol e BHT sobre a estabilidade t?rmica e oxidativa do biodiesel de algod?o (B100), obtido pelas rotas met?licas e et?licas. Foram determinadas as principais propriedades f?sico-qu?micas do ?leo de algod?o e do B100, al?m das caracteriza??es atrav?s de Espectroscopia de Absor??o na Regi?o de Infravermelho (FTIR) e Cromatografia Gasosa (CG). O estudo da efici?ncia dos antioxidantes adicionados, nas concentra??es de 200, 500, 1000, 1500 e 2000 ppm, para as estabilidades t?rmicas e oxidativa, foi realizado atrav?s da Termogravimetria (TG), An?lise T?rmica Diferencial (DTA), Calorimetria Explorat?ria Diferencial (DSC), Calorimetria Explorat?ria Diferencial sob Press?o (P-DSC) e Rancimat. As amostras de biodiesel apresentaram-se dentro das especifica??es estabelecidas pela Resolu??o da ANP No 7/2008. A adi??o de ambos os antioxidantes, mesmo em baixa concentra??o (200 ppm), aumentou a estabilidade t?rmica dos B100. Atrav?s das curvas DTA e DSC, foram estudadas as transi??es f?sico-qu?micas ocorridas no biodiesel. O tempo inicial (OIT) e temperatura (Tp) de oxida??o, determinados atrav?s das curvas P-DSC, mostraram que o α-tocoferol tem comportamento pr?-oxidante para algumas concentra??es elevadas. O BHT apresentou melhor resultado do que o α-tocoferol, com rela??o ? resist?ncia ? oxida??o
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Kirker, Grant Terral. "Effects of chlorothalonil (CTN) and butylated hydroxy-toluene (BHT) on microbial communities involved in the deterioration of wood using terminal restriction fragment length polymorphism (T-RFLP) analyses." Diss., Mississippi State : Mississippi State University, 2008. http://library.msstate.edu/etd/show.asp?etd=etd-04022008-155301.
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Richardot, Thomas. "Développement d'un matériau piézoélectrique sans plomb pour la réalisation de sondes ultrasonores haute fréquence." Thesis, Tours, 2016. http://www.theses.fr/2016TOUR4011/document.
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L’échographie haute résolution est une technique d’imagerie médicale permettant une observation du corps de très bonne définition, à faible profondeur (quelques micromètres). Pour réaliser cela, des ondes ultrasonores sont utilisées (quelques dizaines de mégahertz), produites par l’élément actif de la sonde: un film piézoélectrique. Pour atteindre de telles fréquences, cet élément doit être d’une épaisseur déterminée: de l’ordre de la dizaine de micromètres. Aujourd’hui, le PZT, zirconotitanate de plomb, est le matériau piézoélectrique démontrant les meilleures propriétés pour de telles applications. Mais des évolutions législatives sont en cours pour restreindre son utilisation, du fait des risques que représente le plomb pour la santé et l’environnement. Le défi actuel dans le domaine des matériaux piézoélectriques est de trouver un matériau de substitution. C’est l’objectif de cette étude. Un matériau piézoélectrique sans-plomb choisi dans la littérature, le BHT, ou titanate de baryum dopé à l’hafnium, est étudié, dans le but de remplacer le PZT dans les appareils échographiques. Le procédé sol-gel composite est ensuite utilisé pour sa mise en œuvre sous forme de films épais piézoélectriquesUltrasonography is a medical imaging technique that allows exploring, with high resolution, a body in a few micrometers depth. For this purpose, ultrasonic waves , produced with a piezoelectric film, are used. This film must have a thickness of at least few micrometers to yield megahertz waves. Nowadays , PZT , lead zirconate titanate, is the key material for such applications. But since recently, a change has come in lead exploitation. It is recommended by the authorities to use another material when it is possible, which became a big challenge in piezoelectric material researches . Therefore, the aim of this study is to investigate a lead-free piezoelectric material in the purpose to use it in ultrasound echography. The selected material is BHT, barium hafnate titanate, and it is shaped as a thick film using sol-gel composite proceed
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Bacha, Kenza. "Interaction entre les carburants diesel et biodiesel et les composants du système d'injection diesel." Thesis, Mulhouse, 2016. http://www.theses.fr/2016MULH4471.
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Le système d’injection Diesel doit résister à des conditions opératoires (pression, température) de plus en plus sévères, et être compatible avec les évolutions du carburant diesel, telles que l’introduction des Esters Méthyliques d’Acide Gras (EMAG) et l’utilisation de différents additifs, qui peuvent affecter la durabilité des véhicules, suite à la formation de dépôts. L’objectif des travaux de cette thèse est la compréhension des mécanismes de formation des dépôts issus de l’oxydation des carburants et la détermination des paramètres majeurs participant aux interactions dépôts-substrats (état de surface, matériaux, géométrie, thermique…). Deux études ont été abordées dans cette thèse. La première étude porte sur l’oxydation accélérée des carburants Diesel, des EMAG et des mélanges Diesel/EMAG en phase liquide en utilisant le moyen d’essai PetroOxy, la cinétique d’oxydation a été déterminée pour les différents carburants et la caractérisation des produits d’oxydation a été effectuée utilisant les moyens d’analyse (FTIR-ATR, ATG/DTG et GC/MS). La seconde étude est dédiée à la reproduction du dépôt sur les substrats en (aluminium, acier inoxydable, PEEK, revêtement or sur aluminium, revêtement silcoklean sur acier inoxydable) en utilisant le moyen d’essai Micro Cokage et la caractérisation du dépôt obtenu dans chaque cas en utilisant les moyens d’analyse (FTIR-ATR, ATG/DTG, FEG et XPS). Les résultats de ces travaux ont permis de déterminer l’impact de la nature et du taux d’EMAG ajouté au Diesel sur la stabilité à l’oxydation des carburants ; de mettre en place une hypothèse de formation de dépôt à partir de l’oxydation des carburants en phase liquide jusqu’à la formation de nanoparticules de dépôt sphériques ; et déterminer l’impact du substrat sur la formation et l’adhésion du dépôt à la surface du matériauDiesel injection system must withstand more severe operating conditions (pressure, temperature), and be compatible with the evolution of diesel fuel, such as the introduction of Fatty Acid Methyl Esters (FAME) and use of different additives, which may affect the durability of the vehicle, following the formation of deposits. The objective of this work is to understand the mechanisms of deposit formation from fuel oxidation and determine the major parameters involved in deposit-substrate interactions (surface condition, materials, geometry, temperature...). Two studies were discussed. The first study focuses on the liquid phase accelerated oxidation of Diesel fuel, FAME and mixtures (Diesel / FAME) using PetroOxy device, the oxidation kinetic was determined for the different fuels and characterization of oxidation products was carried out using the (FTIR-ATR, ATG / DTG and GC / MS). The second study was dedicated to the reproduction of deposit on different substrates (aluminum, stainless steel, PEEK, aluminum coating on gold, silcoklean coating on stainless steel) using the Micro Coking device, and characterization of the deposit obtained in each case using (FTIR-ATR, ATG / DTG, XPS and FEG). The results of this work permit to determine the impact of FAME nature and FAME concentration on fuel oxidation stability; an hypothesis was proposed to explain deposit formation
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Trelcat, Jean-François. "Synthèses par voies solide et hydrothermale pour céramiques de type BNT - BT - BKT." Valenciennes, 2010. http://ged.univ-valenciennes.fr/nuxeo/site/esupversions/7f649e27-84b6-4215-952b-cd0b3ee186ad.
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Ce travail a pour objet l’étude de l’un des systèmes les plus prometteurs en tant que substitut au PZT, le ternaire Bi0,5Na0,5TiO3 - BaTiO3 - Bi0,5K0,5TiO3. La première partie de la thèse s’est focalisée sur la synthèse par voie solide de ce système et a permis une estimation plus affinée de la zone de transition de phase morphotropique. Dans une seconde partie, nous nous sommes centrés sur l’élaboration de poudres réactives de BNT par voie hydrothermale. Bien que les divers protocoles mis au point ont permis l’obtention de poudres microniques et cristallisées, toutes se distinguent par l’apparition de phases thermiquement instables en quantités infimes mais néanmoins suffisantes pour entraîner l’apparition d’une macroporosité après frittage. Diverses techniques de lavage ont été développées pour éliminer ces phases métastables. Un compromis a dû être réalisé entre la qualité de l’élimination de ces phases non désirées et le maintien de la composition chimique de la phase majoritaire. Le taux de densification et les propriétés piézoélectriques obtenus sur ces céramiques sont largement comparables à la voie solide. L’étude de la cosynthèse BNT - BT par thermolyse hydrothermale de la composition binaire 0,935 BNT - 0,065 BT n’a pu aboutir et a mis en évidence la précipitation préalable et définitive du titanate de bismuth Bi12TiO20This study focuses on the study of one of the most promising systems as an alternative to PZT, the Bi0,5Na0,5TiO3 - BaTiO3 - Bi0,5K0,5TiO3 ternary system. The first part of the thesis consists on the solid state synthesis of this system and has allowed a more accurate estimation of the morphotropic phase boundary location. In a second part, we focused this study on the development of BNT powders hydrothermal synthesis. Although various protocols have developed the production of fine and single phased powders, all of them are characterized by the presence of thermally unstable phases in minor quantities but nevertheless sufficient to let appear a strong porosity after sintering. Various washing techniques have been developed to eliminate these metastable phases. A compromise between the quality of the metastable phase elimination and the preservation of the major phase chemical composition must be realized. The densification ratio and piezoelectric properties obtained for these ceramics are widely comparable to the solid route synthesized ones. The BNT - BT cosynthesis study of the 0,935 BNT - 0,065 BT binary composition put in evidence the prerequisite and definitive bismuth titanate Bi12TiO20 precipitation
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Gonçalves, Carla Maria Batista. "Barrier properties of poly(lactic acid) based films." Doctoral thesis, Universidade de Aveiro, 2014. http://hdl.handle.net/10773/14296.
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Doutoramento em Engenharia QuímicaIn recent years, the search for a environmentally friendly products has increased. One of the major challenges has been the demand for biodegradable materials that can replace plastic. If a few decades ago, plastic replaced, for example, the ivory in billiard balls, and in other products, saving the lives of thousands elephants, nowadays a replacement for that plastic is being searched, to prevent the change of the environmental conditions, essential to life in harmonly with the fauna and flora that the human specie has, in recent years, destroyed. Plastic is a petroleum derivate, whose price has been growing exponentially, mainly due to the fact of beind a cheap material and also to enable the production of products that are essential to modern life. Therefore, the petrochemical era is going to come to an end and a new environmentally sustainable era, based on biodegradable materials from renewable sources, will follow. The change to green routes only will be possible with the support of the major companies, and the implementation of drastic governmental law. Poly(lactic acid), PLA, is produced from the lactose present in the corn or sugarcane and has been intensively studied in recent years because if some limitants properties required its extrusion are overcome, it has the potential to replace the traditional polymers. PLA have high brittleness, low toughness and low tensile elongation. In this work, natural antioxidant (alpha-tocopherol) and synthetics antioxidants (BHT ant TBHQ) were added to the PLA with the aim not only to improve their flexibility, but also to create an active packaging to extend the shelf life of the foods and improve the organoleptic properties by preventing food losses. The impact of the addition of antioxidants into the PLA films, in its mechanical, thermal and barrier properties were studied by FTIR, DSC, SEM, AFM, DMA, TGA, QCM and time-lag techniques.
Nos últimos anos temos assistido à procura de produtos amigos do ambiente. Um dos maiores desafios tem sido a procura de materiais biodegradáveis que possam substituir materiais vulgarmente designados por “plástico”. Se há dezenas de anos o plástico veio, por exemplo, substituir o marfim nas bolas de bilhar, salvando vidas de milhares de elefantes, hoje, procuramos um substituto para esse plástico, de forma a preservar as condições ambientais que nos permitem viver harmoniosamente com a restante fauna e flora, e que a espécie humana tem, nos últimos anos, vindo a destruir. O plástico é um derivado do petróleo, cujo preço tem vindo a crescer exponencialmente, devido ao facto de ser barato e possuir propriedades que permitem desenhar produtos essenciais à vida quotidiana. Por isso, precisamos de sair da era petroquímica e entrar numa nova era ambientalmente sustentável, baseada em materiais biodegradáveis provenientes de fontes renováveis. Esta mudança para rotas “verdes”, só será possível com o apoio de grandes empresas, e medidas governamentais drásticas. O poliácido láctico, PLA, produzido a partir da lactose presente no amido ou no açúcar, tem sido intensivamente estudado nos últimos anos e possui potencial para substituir os tradicionais polímeros derivados do petróleo, se forem melhoradas algumas propriedades necessárias ao processamento por extrusão. O PLA, é muito frágil, pouco resistente e pouco flexível. Neste trabalho foram adicionados antioxidantes naturais (alfa-tocoferol) e sintéticos (BHT e TBHQ) ao PLA com o objetivo não só de melhorar as suas propriedades mecânicas, mas também de criar uma embalagem ativa que prolongue o prazo de validade dos alimentos e melhore as suas propriedades organoléticas prevenindo alterações ou perda de sabor. O impacto da adição destes antioxidantes nas propriedades originais do PLA a nível mecânico, térmico e de barreira foi estudado pela utilização das técnicas de FTIR, DSC, SEM, AFM, DMA, TGA, QCM e time-lag.
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Knight, Michael K. "Bit by bit." Claremont Graduate University, 2010. http://ccdl.libraries.claremont.edu/u?/stc,82.
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Malm, Martin. "Beckholmen bit för bit." Thesis, KTH, Arkitektur, 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-150351.
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På Beckholmen ligger stockholmsregionens enda aktiva reparationsvarv med kapacitet att ta emot såväl större fartyg samt skärgårdstrafikens fartyg. För att kunna bedriva verksamheten på ett säkert och miljövänligt sätt krävs infrastrukturella investeringar i form av byggnader och anläggningar. Stockholms stad har påbörjat ett programarbete och presenterat ett förslag till detaljplan som möjliggör dessa investeringar. Då det handlar om stora investeringar och förändringar i stadsbilden är den nya detaljplanen ett känsligt projekt, särskilt om varvsverksamheten skulle hamna i ekonomiska svårigheter. I det förslag till detaljplan som presenterats hösten 2012 har varsverksamhetens funktioner lagts inom en och samma byggnadsvolym, som till en följd blir väldigt stor. Frågeställningen i ”Beckholmen bit för bit” är om en detaljplan som låter verksamheten växa mer inkrementellt fördelat på fler byggnader kan göra projektet mer flexibelt. Efter studier av varvsverksamhetens program samt volym och planstudier, blir slutsatsen att det finns fördelar med att fördela varvsfunktionerna på fler byggnadsvolymer. Särskilt om byggnaderna gestaltas på ett sätt så att kompositionen är öppen för förändring. Ett förslag på en gestaltning som uppfyller dessa egenskaper presenteras även.The only active shipyard in the Stockholm region with capacity for large ships and the archipelago fleet is situated at Beckholmen. Large investments in infrastructure and buildings are needed in order to secure the enviroment and worker safety. The city has presented a proposal for new planning enabeling these investments. As the investment are large and the site is sensitive the project has many potential risks, especially if the shipyard should encounter economic difficulties in the future. In the citys planning proposal presented in 2012 the whole program for the shipyard is contained within one single volume. The question at issue in ”Beckholmen bit by bit” thus is if planning that splits the program into separate buildings and permits incremental growth is prefarable. After program studies, volume and plan studies the conclusion is that there are many advantages with planning that encourages incremental growth of the shipyard at Beckholmen, especially if the building design is open to change from the beginning. A proposal of a planning and design fulfilling these qualities is also presented.
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Garibaldi, Cynthia. "Détermination des températures profondes du Bassin du Sud-Est de la France et relations entre anomalies thermiques, géologie et circulations hydrothermales par modélisation 3D." Phd thesis, Université de Nice Sophia-Antipolis, 2010. http://tel.archives-ouvertes.fr/tel-00493961.
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Les précédentes estimations des températures profondes en France mettent en évidence trois anomalies thermiques positives principales dont une est centrée entre Marseille et Montpellier. Ce travail de thèse présente l'étude du régime thermique du Bassin du Sud-Est à partir d'une réévaluation des températures profondes corrigées des effets thermiques transitoires générés lors des mesures en forage pétrolier. 203 données BHT corrigées et 10 DST (mesures stables) issues de 103 forages ont ainsi été obtenues. Le gradient thermique moyen du Bassin (31,3°C/km) est proche de la moyenne française (32,5°C/km) mais les gradients locaux varient d'environ 20 à 45°C/km. Une analyse géostatistique nous a permis de construire un modèle thermique de représentation 3D de la surface à 6km de profondeur duquel nous avons extrait des coupes et cartes thermiques à différentes profondeurs. De nouvelles anomalies thermiques de plus petite échelle ont ainsi pu être identifiées, certaines étant positives (du côté de Montpellier, Lodève, Gap et La Drôme) et d'autres négatives (dans les Cévennes et la région d'Aix-en-Provence). Une compilation de données géophysiques nous a permis de discuter ces anomalies en termes de géologie locale et de phénomènes à grande échelle (variations de profondeur du Moho, épaisseur des sédiments), mais il semble que des circulations de fluides puissent mieux expliquer la localisation, l'amplitude et les longueurs d'ondes des signaux thermiques qui suivent la direction des failles majeures en surface. Le rôle de la circulation de fluides dans la mise en place et l'évolution des anomalies thermiques au sein des zones de faille est illustré par des modèles numériques en régime stationnaire et transitoire. Ces modèles permettent de reproduire des anomalies de plusieurs dizaines de degrés. Ce phénomène est amplifié lorsqu'une anisotropie de perméabilité est prise en compte. De plus, la dépendance de la perméabilité avec la profondeur permet d'obtenir des superpositions d'anomalies positives et négatives sur un même profil vertical comme nous l'observons sur les coupes thermiques issues des mesures. Loin des zones perméables, les anomalies peuvent s'expliquer par des processus conductifs au sein d'objets dans lesquels les contrastes de conductivité thermique peuvent être importants. L'anisotropie de conductivité dans les formations argileuses peut être responsable du développement d'anomalies proches de celles observées entre les zones perméables. Enfin, les circulations hydrothermales dans les zones de faille associées à des sédiments anisotropes pourraient expliquer la forme, l'évolution en profondeur et l'intensité des anomalies thermiques identifiées.
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Aoujgal, Ahmed. "Etude des propriétés physico-chimiques et électroniques de matériaux ferroélectriques sous forme de céramiques et de films minces en vue d'applications radiofréquences et microondes." Littoral, 2010. http://www.theses.fr/2010DUNK0285.
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L’objectif du présent travail est de concevoir, réaliser et optimiser des matériaux accordables pour des applications en électronique à hautes fréquences. Le composant le plus simple permettant de mettre à profit cette étude est le condensateur accordable avec une tension continue qui peut être ensuite intégrée dans des dispositifs microondes accordables ou reconfigurables. Le condensteur peut être en couches minces ou en céramique. Pour réaliser de tels composants, on doit utiliser des matériaux présentant de faible pertes diélectriques, une permitivité élevée, une accordabilité importante et une bonne stabilité de la fréquence de résonance avec la température. Pour cela, nous avons mené une étude sur des matériaux ferroélectriques classiques et relaxeurs afin, d’une part d’optimiser les conditions de synthèse, et d’autre part d’améliorer leurs propriétés électriques pour des applications radiofréquences et microondes. Nous avons étudié des matériaux ferroélectriques de phase pérovskite. Il s’agit du titane de baryum et de strontium (BST) qui est un ferroélectrique classique, du titane de baryum et de zircone (BZT) qui selon sa composition peut être classique ou relaxeur et des dérivées du BZT obtenues par substitution au niveau des sites pérovskites a et b respectivement par du bismuth et par du zinc-niobium. Nous avons aussi synthétisé et caractérisé des matériaux de phase pyrochlore de formule Bi1. 5ZnNb1. 5O7. Ces études vont de l’élaboration de tous ces matériaux sous forme de céramiques et de couches minces, suivies de caractérisations physico-chimiques, structurales, diélectriques et ferroélectriques dans une large gamme de fréquences et de températuresThe main objective of this work is to design, implement and optimize tunable materials for electronic applications at high frequencies. The easiest component to build on this study is the tunable capacitor with a voltage which can then be integrated into microwave devices such as tunable or reconfigurable resonators, filters, antennas. . . Etc. The capacitor can be either thin film or ceramic-based. To produce such components we must use materials which must have low dielectric loss, high dielectric permittivity, high tunability and stability of the resonant frequency of the capacitor with the temperature. For this, we conducted a detailed study of classical and relaxor ferroelectric materials in order, firstly to optimize the synthesis conditions, and secondly to improve their electrical properties for radiofrequencies and microwave applications. We have studied ferroelectric materials with perovskite phase, namely barium titanate strontium (BST) which is a classical ferroelectric and barium zirconium (BZT) which according to its composition can be a classical ferroelectric or relaxor ferroelectric and the derivatives of BaZr0. 1Ti0. 9O3 obtained by substituting bismuth and zinc-niobium respectively at A and B sites of the perovskite phase. We also synthesized and characterized the pyrochlore phase materials of bismuth zinc niobate, with composition of Bi1. 5ZnNb1. 5O7. The studies we have done range from the development of these materials in the form of ceramics and thin films, followed by characterizations to determine their physico-chemical properties, structural dielectric and ferroelectric in a range wide of frequencies and temperature
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Redinger, Petra Best Troy L. "Variation in populational size and composition within two summer colonies of endangered gray bats (Myotis grisescens)." Auburn, Ala., 2006. http://repo.lib.auburn.edu/2006%20Spring/master's/REDINGER_PETRA_52.pdf.
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Celtikci, Baris. "Preparation Of Lead-free Bzt-bct Thin Films By Chemical Solution Deposition And Their Characterization." Master's thesis, METU, 2012. http://etd.lib.metu.edu.tr/upload/12614623/index.pdf.
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In the presented thesis, lead-free Ba(Ti0.8Zr0.2)O3-(Ba0.7Ca0.3)TiO3 (BZT-BCT) thin films were deposited on Pt/TiO2/SiO2/Si substrates using chemical solution deposition method and then the effect of process parameters were investigated to obtain optimum parameters of these lead-free thin films. The phase was selected near to the morphotropic phase boundary (MPH) to increase the number of polarization directions where rhombohedral and tetragonal phases exist together.
In this study, the effect of sintering temperatures on microstructure, dielectric and ferroelectric properties were studied systematically. Among the various high-quality BZT-BCT thin films with uniform thickness, the optimum dielectric and ferroelectric responses were observed for films annealed at 800 oC for 1 h sintering time. The thickness was kept constant for all measurements as 500 nm (triple layered films). Therefore, the average grain sizes were found around 60 nm for samples sintered at 700,750 and 800 oC.
BZT-BCT thin films sintered at 800 oC showed effective remnant polarization and coercive field values of 2.9 µC/cm2 and 49.4 kV/cm, together with a high dielectric constant and low loss tangent of 365.6 and 3.52 %, respectively, at a frequency of 600 kHz due to pure perovskite phase showing full crystallization and minimum surface porosity obtained at this temperature.
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Hoesel, Stan van. "De constructie van de informatiesnelweg "bit by bit" /." [Maastricht : Maastricht : Universiteit Maastricht] ; University Library, Maastricht University [Host], 2001. http://arno.unimaas.nl/show.cgi?fid=13064.
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North, Phillip. "One-Bit Compressive Sensing with Partial Support Information." Scholarship @ Claremont, 2015. http://scholarship.claremont.edu/cmc_theses/1194.
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This work develops novel algorithms for incorporating prior-support information into the field of One-Bit Compressed Sensing. Traditionally, Compressed Sensing is used for acquiring high-dimensional signals from few linear measurements. In applications, it is often the case that we have some knowledge of the structure of our signal(s) beforehand, and thus we would like to leverage it to attain more accurate and efficient recovery. Additionally, the Compressive Sensing framework maintains relevance even when the available measurements are subject to extreme quantization. Indeed, the field of One-Bit Compressive Sensing aims to recover a signal from measurements reduced to only their sign-bit. This work explores avenues for incorporating partial-support information into existing One-Bit Compressive Sensing algorithms. We provide both a rich background to the field of compressed sensing and in particular the one-bit framework, while also developing and testing new algorithms for this setting. Experimental results demonstrate that newly proposed methods of this work yield improved signal recovery even for varying levels of accuracy in the prior information. This work is thus the first to provide recovery mechanisms that efficiently use prior signal information in the one-bit reconstruction setting.
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Vivian, Darlan. "Ariadne-BFT." Florianópolis, SC, 2007. http://repositorio.ufsc.br/xmlui/handle/123456789/90028.
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Dissertação (mestrado) - Universidade Federal de Santa Catarina, Centro Tecnológico. Programa de Pós-Graduação em Ciência da Computação.Made available in DSpace on 2012-10-23T05:20:15Z (GMT). No. of bitstreams: 1 240731.pdf: 888300 bytes, checksum: 247a9d9a95ae0d19f44c9efcd4411b18 (MD5)
As redes sem fio ad hoc surgiram para estender a mobilidade e a flexibilidade no ambiente sem fio, onde um conjunto de nós, que podem agir como roteadores, formam a infra-estrutura de roteamento na rede. A maioria dos protocolos de roteamento propostos não utiliza mecanismos de segurança, pois assumem que o ambiente é composto apenas por nós confiáveis. Mas devido à mudança dinâmica de topologia e ambiente aberto, uma rede ad hoc é extremamente vulnerável à presença de nós maliciosos os quais podem degradar desempenho ou até mesmo impedir o funcionamento da rede. Para evitar ou minimizar os problemas causados pela falta de segurança, os seguintes protocolos de roteamento seguro foram propostos: Ariadne, SAODV, BFTR, SEAD e ARAN. Neste contexto, a presente dissertação tem como objetivo analisar estes protocolos de roteamento seguro utilizados em redes sem fio ad hoc e propor melhorias nos mecanismos de segurança projetados para proteger a rede contra ataques interrupção de roteamento e de consumo de recursos. Como resultado desta análise, é proposto o Ariadne-BFT (Ariadne Best-effort Fault-Tolerant), uma extensão do protocolo de roteamento seguro Ariadne baseado nos algoritmos de descoberta e seleção de rotas do protocolo BFTR. O Ariadne-BFT incrementa a segurança no roteamento em relação ao protocolo Ariadne original, com a proteção contra o ataque Blackhole. Experimentos são executados sob a forma de simulações para análise e comparação de desempenho, através das quais é demonstrado que o protocolo Ariadne-BFT possui um desempenho superior em relação às métricas latência e razão de entrega de pacotes.
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Abreu, Victor Vicente. "Balance-bot." Master's thesis, Universidade da Madeira, 2009. http://hdl.handle.net/10400.13/59.
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Research on inverted pendulum has gained momentum over the last decade on a number
of robotic laboratories over the world; due to its unstable proprieties is a good example
for control engineers to verify a control theory. To verify that the pendulum can
balance we can make some simulations using a closed-loop controller method such as
the linear quadratic regulator or the proportional–integral–derivative method.
Also the idea of robotic teleoperation is gaining ground. Controlling a robot at a
distance and doing that precisely. However, designing the tool to takes the best benefit
of the human skills while keeping the error minimal is interesting, and due to the fact
that the inverted pendulum is an unstable system it makes a compelling test case for
exploring dynamic teleoperation.
Therefore this thesis focuses on the construction of a two-wheel inverted pendulum
robot, which sensor we can use to do that, how they must be integrated in the system
and how we can use a human to control an inverted pendulum.
The inverted pendulum robot developed employs technology like sensors, actuators and controllers. This Master thesis starts by presenting an introduction to inverted pendulums and some information about related areas such as control theory. It continues by describing related work in this area. Then we describe the mathematical model of a two-wheel inverted pendulum and a simulation made in Matlab. We also focus in the construction of this type of robot and its working theory. Because this is a mobile robot we address the theme of the teleoperation and finally this thesis finishes with a general conclusion and
ideas of future work.Orientador: Ian Oakley
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Caputo, Robert Thomas. "Bat parts." Thesis, University of Iowa, 2014. https://ir.uiowa.edu/etd/4586.
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Moen, Selmer, and Charles Jones. "BIT RATE AGILITY FOR EFFICIENT TELEMETRY." International Foundation for Telemetering, 2003. http://hdl.handle.net/10150/606754.
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International Telemetering Conference Proceedings / October 20-23, 2003 / Riviera Hotel and Convention Center, Las Vegas, NevadaThe Bit Rate Agile Onboard Telemetry Formatting (BRAOTF) system was developed by Killdeer Mountain Manufacturing to address increasing demands on the efficiency of telemetry systems. The BRAOTF thins and reorders data streams, adjusting the bit rate of a pulse code modulation (PCM) stream using a bit-locked loop to match the desired information rate exactly. The BRAOTF accomplishes the adjustment in hardware, synthesizing a clock whose operating frequency is derived from the actual timing of the input format. Its firmware manages initialization and error management. Testing has confirmed that the BRAOTF implementation meets its design goals.
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Karaer, Arzu. "Optimum bit-by-bit power allocation for minimum distortion transmission." Texas A&M University, 2005. http://hdl.handle.net/1969.1/4760.
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In this thesis, bit-by-bit power allocation in order to minimize mean-squared error (MSE) distortion of a basic communication system is studied. This communication system consists of a quantizer. There may or may not be a channel encoder and a Binary Phase Shift Keying (BPSK) modulator. In the quantizer, natural binary mapping is made. First, the case where there is no channel coding is considered. In the uncoded case, hard decision decoding is done at the receiver. It is seen that errors that occur in the more significant information bits contribute more to the distortion than less significant bits. For the uncoded case, the optimum power profile for each bit is determined analytically and through computer-based optimization methods like differential evolution. For low signal-to-noise ratio (SNR), the less significant bits are allocated negligible power compared to the more significant bits. For high SNRs, it is seen that the optimum bit-by-bit power allocation gives constant MSE gain in dB over the uniform power allocation. Second, the coded case is considered. Linear block codes like (3,2), (4,3) and (5,4) single parity check codes and (7,4) Hamming codes are used and soft-decision decoding is done at the receiver. Approximate expressions for the MSE are considered in order to find a near-optimum power profile for the coded case. The optimization is done through a computer-based optimization method (differential evolution). For a simple code like (7,4) Hamming code simulations show
that up to 3 dB MSE gain can be obtained by changing the power allocation on the
information and parity bits. A systematic method to find the power profile for linear block codes is also introduced given the knowledge of input-output weight enumerating function of the code. The information bits have the same power, and parity bits
have the same power, and the two power levels can be different.
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Sandvik, Jørgen Moe. "En variabel bit lengde 9-bit 50MS/S SAR ADC." Thesis, Norges teknisk-naturvitenskapelige universitet, Institutt for elektronikk og telekommunikasjon, 2012. http://urn.kb.se/resolve?urn=urn:nbn:no:ntnu:diva-20654.
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A 9-bit 50MS/s SAR ADC with a simulated power consumption of 24.5 µW was designed for this thesis. Specifications were made for application with in-probe electronic as part of an ultrasound system. A novel switching-scheme - employing variable bit length encoding – was introduced in order to simplify successive approximation. Pre-layout results reported a FoM of just 1.37 fJ/conversion step, which is favorable to all published designs to date. Recent technology advancements has seen the ultrasound field expanding into handheld markets [33]. More power efficient solutions, in addition to existing enhanced resolution 3-D technology both place strict requirements for analog/mixed-signal design. Composite electronics within the probe casing - allowing close-to-source signal processing - is believed to be the future of ultrasound devices. ADC designs suitable for in-probe technology require ultra low power and noise characteristics towards supporting multiple channels on a single SoC. Excellent performance of recent SAR ADCs make them a viable alternative for in-probe technology [2,7,12,4]. Work in this thesis show the flexibility of the SAR algorithm. The relatively simple implementation/decoding of the VBL approach, complimented by the accuracy dependency of the level detection range makes the ADC reconfigurable by digital signal processing. Recent published design has reported relatively low power consumption for the comparator [15,7]. A motivation for the thesis was to see whether multiple operated comparators could reduce power in remaining circuitry. Implementation of a level-detector - supporting the VBL switching-scheme - has lead to improvements in: Power efficiency, speed and metastability-induced errors. The device consists of two comparators operated in parallel, with a relative DC-offset generated by difference in the capacitive load. Decision points of the comparators shift with DC-offset, and are atoned for a range desired by the modified SAR algorithm. An extensive literary search of recent methodologies and results was conducted, and a summery presenting state-of-the-art designs is included with the work. An approach using no external references where chosen as a basis for the DAC design. Emphasize was made on constant common-mode voltage suitably for comparator design eliminating pre-amplifiers or buffers. Digital logic consisting of serial connected bitslices using a novel differential approach is proposed. Level detector outputs are connected to the digital logic switching only a portion of transistors in the bitslice during conversion. Trade-off between switching activity and circuit area proves effective, with only 12.5% of overall power consumed in the digital part. Power simulations reported the level-detector as the dominant source of consumption, thereby being subject to further optimization with regards to power. Nonetheless a proof-of-concept 8-bit ADC implementation - operated with the novel switching-scheme - produced 8.96 ENOB while dissipating less power.
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James, Calvin L. "ENHANCE BIT SYNCHRONIZER BIT ERROR PERFORMANCE WITH A SINGLE ROM." International Foundation for Telemetering, 1990. http://hdl.handle.net/10150/613417.
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International Telemetering Conference Proceedings / October 29-November 02, 1990 / Riviera Hotel and Convention Center, Las Vegas, NevadaAlthough prefiltering prevents the aliasing phenomenon with discrete signal processing, degradation in bit error performance results even when the prefilter implementation is ideal. Degradation occurs when decisions are based on statistics derived from correlated samples, processed by a sample mean estimator. i.e., a discrete linear filter. However, an orthonormal transformation can be employed to eliminate prefiltered sample statistical dependencies, thus permitting the sample mean estimator to provide near optimum performance. This paper will present mathematical justification for elements which adversely affect the bit synchronizer’s decision process and suggest an orthonormal transform alternative. The suggested transform can be implemented in most digital bit synchronizer designs with the addition of a Read Only Memory (ROM).
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Tölch, Ulf. "Bat Time Stories." Diss., lmu, 2006. http://nbn-resolving.de/urn:nbn:de:bvb:19-51308.
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Barrett, Janine. "Australian bat lyssavirus /." St. Lucia, Qld, 2004. http://adt.library.uq.edu.au/public/adt-QU20040729.134623/index.html.
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Sullivan, Lawrence. "Bat Problem Management." College of Agriculture and Life Sciences, University of Arizona (Tucson, AZ), 2000. http://hdl.handle.net/10150/146697.
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Segars, Tara. "8-Bit Hunger." Kent State University / OhioLINK, 2021. http://rave.ohiolink.edu/etdc/view?acc_num=kent1619176909244462.
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Bonaiuti, Davide. "Progettazione e sviluppo di un'applicazione per la gestione degli appuntamenti tra professionisti e clienti." Bachelor's thesis, Alma Mater Studiorum - Università di Bologna, 2016. http://amslaurea.unibo.it/11865/.
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Tutti coloro che lavorano su appuntamento hanno una clientela da gestire. Per farlo, possono avvalersi di due opzioni: o utilizzano una buona parte del loro tempo per rispondere direttamente alle chiamate e ai messaggi dei clienti, oppure assumono una persona che si faccia carico personalmente dell’agenda del negozio, piuttosto che dello studio, a seconda dei casi.
Gli aspetti negativi di queste due scelte non mancano. Nel primo caso, il diretto interessato può trovarsi interrotto da una chiamata nel pieno di un appuntamento. Il cliente lì presente deve attendere pazientemente che la conversazione finisca, ma la pazienza, giustamente, inizia a vacillare nel momento in cui le chiamate diventano numerose. Oltretutto la situazione può creare disagio al professionista in prima persona. In alcuni casi, inoltre, il cliente a casa è costretto ad aspettare tempi troppo lunghi prima di ricevere una risposta. Nel secondo caso, si ha un lavoro più fluido e senza interruzioni. Questo è ovviamente un fattore positivo, tuttavia l’assunzione di un addetto a rispondere al telefono, piuttosto che a messaggi o mail, ha un costo non indifferente.
Analizzando i vari vantaggi e svantaggi dei metodi di prenotazione esistenti, è stata progettata una nuova soluzione che, tramite l'utilizzo dei bot e delle app di messaggistica, permette di prendere gli appuntamenti rimanendo il più fedeli possibile ai metodi classici, come i messaggi, ma con tutti i vantaggi dei metodi più tecnologici.
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Gilani, Syed Zafar ul Hussan. "Understanding the behaviour and influence of automated social agents." Thesis, University of Cambridge, 2018. https://www.repository.cam.ac.uk/handle/1810/279022.
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Online social networks (OSNs) have seen a remarkable rise in the presence of automated social agents, or social bots. Social bots are the new computing viral, that are surreptitious and clever. What facilitates the creation of social agents is the massive human user-base and business-supportive operating model of social networks. These automated agents are injected by agencies, brands, individuals, and corporations to serve their work and purpose; utilising them for news and emergency communication, marketing, social activism, political campaigning, and even spam and spreading malicious content. Their influence was recently substantiated by coordinated social hacking and computational political propaganda. The thesis of my dissertation argues that automated agents exercise a profound impact on OSNs that transforms into an array of influence on our society and systems. However, latent or veiled, these agents can be successfully detected through measurement, feature extraction and finely tuned supervised learning models. The various types of automated agents can be further unravelled through unsupervised machine learning and natural language processing, to formally inform the populace of their existence and impact.
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Näslund, Mats. "Bit extraction, hard-core predicates and the bit security of RSA." Doctoral thesis, KTH, Numerical Analysis and Computer Science, NADA, 1998. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-2687.
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Xiao, Xin, Bane Vasic, and Shu Lin. "MULTI-BIT BIT-FLIPPING ALGORITHM FOR COLUMN WEIGHT-4 LDPC CODES." International Foundation for Telemetering, 2017. http://hdl.handle.net/10150/627015.
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Low-density parity-check (LDPC) codes with column weight-4 are widely used in many commu-nication and storage systems. However, traditional hard decision decoding algorithms such as the bit-flipping (BF) algorithm suffer from error floor due to trapping sets in LDPC codes. In this paper, to lower error floor of the BF algorithm over the Binary Symmetric Channel (BSC), we design a set of decoding rules incorporated within the BF algorithm for column weight-4 LDPC codes. Given a column weight-4 LDPC code, the dominate error patterns of the BF algorithm are first specified, and according to the designed rules, additional bits at both variable nodes (VN) and check nodes (CN) provide more information for the BF algorithm to identify the dominate error patterns, so that the BF algorithm could deliberately flip some bits to break them. Simulation results show that the modified BF algorithm eliminates all 4-error patterns and lowers the Bit Error Rate (BER) for at least two orders of magnitude with a trivial increment of complexity.
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Thomenius, Michael James. "B-CELL LYMPHOMA-2 PROTEIN FAMILY, APOPTOSIS AND THE ENDOPLASMIC RETICULUM." Case Western Reserve University School of Graduate Studies / OhioLINK, 2004. http://rave.ohiolink.edu/etdc/view?acc_num=case1080679967.
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Hirt, Samuel James Best Troy L. "Analysis of stable isotopes of hydrogen to determine migrational source of silver-haired bats (Lasionycteris noctivagans) in Alabama." Auburn, Ala, 2008. http://repo.lib.auburn.edu/EtdRoot/2008/SUMMER/Biological_Sciences/Thesis/Hirt_Samuel_52.pdf.
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CHAKRABORTY, S. K., and R. K. RAJANGAM. "PROGRAMMABLE HIGH BIT RATE FRAME SYNCHRONISER." International Foundation for Telemetering, 1989. http://hdl.handle.net/10150/614490.
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International Telemetering Conference Proceedings / October 30-November 02, 1989 / Town & Country Hotel & Convention Center, San Diego, CaliforniaThe first Indian Remote Sensing Satellite was launched on 17th March 1988 from a Soviet Cosmodrome into a 904 Km Polar Sunsynchronous orbit. The data transmission from the satellite is at 5.2 Mega Bits/sec in S-Band and 10.4 Mega Bits/sec in X-Band. The payload data is formatted into custom made 8328 words format. A programmable unique versatile frame sync and Decommutation unit has been developed to test the data from the data handling system during its various phases of development. The system works upto 50 Mega Bits/sec and can handle frame sync code length upto 128 bits and a frame length of 2 Exp 20 bits. Provision has been made for programming the allowable bit errors as well as bit slippages, using a front panel setting. This paper describes the design and implementation of such a high bit rate frame synchroniser developed specially for IRS Spacecraft application. It will also highlight the performance of the system.
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Köhlmoos, Melanie. "Bet-El - Erinnerungen an eine Stadt Perspektiven der alttestamentlichen Bet-El-Überlieferung." Tübingen Mohr Siebeck, 2006. http://deposit.ddb.de/cgi-bin/dokserv?id=2773069&prov=M&dok_var=1&dok_ext=htm.
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