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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
171

Caracterização da comunidade microbiana de biofilme anaeróbio em presença de bifenilas policloradas / Characterization of the microcial community in the presence of polychlorinated biphenyls

Mara Rúbia de Lima e Silva 27 April 2012 (has links)
Bifenilas policloradas (PCBs) são compostos de difícil degradação presentes na composição de ascarel, muito utilizado como fluidos dielétricos e isolantes. Neste contexto, a presente pesquisa teve como objetivo avaliar a diversidade de microrganismos em biofilmes de reatores anaeróbios na presença de PCB empregando Métodos de Microbiologia de Anaeróbios Estritos e de Biologia Molecular. Em reator anaeróbio horizontal de leito fixo (RAHLF), alimentado com etanol, formiato, Triton X-100 (0,1%) e ascarel (1 mL/L), operado com tempo de detenção hidráulica (TDH) de 24 horas, foi retirado a comunidade microbiana do biofilme da espuma de poliuretano. Os grupos microbianos encontrados por meio da clonagem e sequenciamento do gene RNAr 16S para o domínio Bacteria foram relacionados aos filos Thermogae, Proteobacteria (Brachymonas petroleovorans, 100% de similaridade e Methylobacillus, 98% de similaridade), Firmicutes (Clostridium, 97% de similaridade, Syntrophomonas, 100% de similaridade e Sporomusa com 100% de similaridade), Synegistetes (Synergistes, 98% de similaridade), Spirochaetes (Leptonema illini, 98% de similaridade), Aminanaerobia, Deferribacteres, Chlorobi, Chloroflexi e Armatimonadetes. Além disso, como nesse biofilme foram identificadas bactérias redutoras de ferro, procedeu-se a sua quantificação por meio da técnica de tubos múltiplos (NMP, Número Mais Provável) obtendo 5,26 x \'10 POT.12\' NMP/g STV de bactérias redutoras de ferro. Ensaio em batelada foi realizado separadamente sob duas condições: (1) metanogênica e (2) ferro redutora. Em ambas as condições foram adicionadas aroclor 1260 (PCB). Os reatores, sob condição metanogênica, foram alimentados com meio de cultivo Angelidaki e substratos orgânicos (formiato e etanol), além de aroclor 1260 (0,2 \'mü\'g/L). Para simular a condição redutora de ferro foi acrescido ao meio de cultura Angelidaki, EDTA férrico (1,86 g/L). A produção de metano, na presença de aroclor 1260 foi de 3,8 x \'10 POT.-4\' mmol \'CH IND.4\'/g STV. A presença de bactérias ferro redutoras foi confirmada indiretamente pela taxa média de redução férrica (90%) nos reatores em batelada, após 60 dias de operação. Por meio de PCR/DGGE, elaborou-se um dendograma das amostras deste ensaio em batelada (metanogênico e redutor de ferro) comparativamente com as do reator RAHLF (biofilme presente na parede do reator e no material suporte). Os reatores em batelada apresentaram similaridade entre si de 79% e 92% para os domínios Bacteria e Archaea, respectivamente. As amostras do reator RAHLF foram 80% (Bacteria) e 96% (Archaea) similares. A existência de bactérias degradadoras de PCB, bem como, bactérias redutoras de ferro no biofilme anaeróbio contribuiu com informações sobre o consórcio microbiano e sua diversidade. / Polychlorinated biphenyls (PCBs) are compounds of difficult degradation, a component of askarel, which were used widely as coolants and lubricants. Hence, this study evaluated the diversity of microorganisms in the presence of PCBs in anaerobic reactors. For such, methods as Strict Anaerobic Microbiology and Molecular Biology were employed. The microbial community of the biofilm, developed in a fixed horizontal bed anaerobic reactor (RAHLF), was studied using the technique of cloning and sequencing of RNAr 16S gene for the Bacteria domain. The reactor had immobilized cells in polyurethane foam with ethanol and formate as a carbon source, Triton X-100 (0.1%) and polychlorinated biphenyls (1 mL/L), and operated with 24 hours HRT. The microbial groups found in this biofilm were related to phyla Thermogae, Proteobacteria (Brachymonas petroleovorans, 100% similarity and Methylobacillus, 98% similarity), Firmicutes (Clostridium, 97% similarity Syntrophomonas, and 100% similarity with Sporomusa 100% similarity), Synegistetes (Synergistes, 98% similarity), Spirochaetes (Leptonema Illini, 98% similarity), Aminanaerobia, Deferribacteres, Chlorobi, Chloroflexi and Armatimonadetes. Furthermore, as bacteria that reduce iron were found, we proceeded the quantification by the multiple tube method (MPN) for this group, obtaining 5.26 x \'10 POT.12\' MPN/g STV of iron-reducing bacteria. The batch reactors evaluated the growth of microorganisms in two condictions: (1) methanogenic e (2) iron reduction, both had the presence of PCBs (Aroclor 1260). The reactor, under methanogenic condition, was fed with synthetic substrate Angelidaki, ethanol and formate, used as carbon source, and aroclor 1260 (0.2 \'mü\'g /L). To simulate the condition of iron reducing, the same synthetic substrate was supplemented with ferric EDTA (1.86 g/L). The production of methane in the presence of aroclor 1260, was 3.8 x \'10 POT.-4\' mmol \'CH IND.4\'/g STV. The presence of iron reducing bacteria, after 60 days, was confirmed indirectly by the average rate of iron ferric reduction (90%). Filogenetics analysis (PCR/DGGE) compared the samples of this batch reactor - methanogenic and reduction of iron ferric -, with the samples of RAHLF - the biofilm in the reactor wall and the support material. The two condictions in batch reactors showed similarity of 79% and 92% respectively for the Bacteria and Archaea domain. Therefore, both samples of RAHLF showed 80% (Bacteria) and 96% (Archaea) of similarity. In other words, more similarity were presented due configuration of the reactor as well as the type of PCB added. As a result, the existence of PCBs degrading bacteria and iron-reducing bacteria in anaerobic biofilm, provided informations about the microbial consortium and its diversity in the presence of PCB.
172

Hidrogenação do tolueno em fase líquida com catalisadores de Ni e Ru suportados em alumina : efeitos do pH e da natureza do agente redutor empregados na preparação dos sólidos por impregnação úmida / Toluene hydrogenation in liquid phase with Ni and Ru catalysts supported on alumina : effects of the pH and the nature of the reducing agent employed in the preparation of the solids by wet impregnation

Ganzaroli, Daiana Rezende, 1985- 06 June 2014 (has links)
Orientador: Antonio José Gomez Cobo / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Química / Made available in DSpace on 2018-08-25T04:45:50Z (GMT). No. of bitstreams: 1 Ganzaroli_DaianaRezende_M.pdf: 2594677 bytes, checksum: 083b3d18fb22abe80176433b885c8c2a (MD5) Previous issue date: 2014 / Resumo: A hidrogenação de compostos aromáticos tem sido muito estudada devido à sua ampla gama de aplicações industriais, bem como às restrições ambientais impostas por diversos países. Nesse contexto, o presente trabalho tem o objetivo estudar os efeitos do pH de impregnação e da natureza do agente redutor sobre o desempenho de catalisadores de Ni e Ru suportados em ?-Al2O3, empregados na hidrogenação de tolueno em fase líquida. Para tanto, catalisadores foram preparados a partir de soluções aquosas dos precursores de NiCl3.6H2O e RuCl3.xH2O, através de impregnação úmida conduzida a pH constante entre 4 e 8. Durante a impregnação, catalisadores foram reduzidos a 353 K (80 ºC) em fase líquida, empregando-se formaldeído (H2CO) ou boroidreto de sódio (NaBH4) como agentes redutores. Os catalisadores de Ni e Ru também foram reduzidos sob fluxo de H2 a 773 e 573 K (500 e 300 ºC) respectivamente, após a impregnação úmida. O suporte foi caracterizado utilizando as técnicas de análise granulométrica, adsorção de N2 (método de B.E.T.) e titulação potenciométrica. As técnicas de MEV+EDX e XPS foram empregadas para determinar a composição química dos sólidos empregados, e a formação da fase ativa dos catalisadores foi estudada através de TPR. O desempenho dos catalisadores foi avaliado na reação de hidrogenação do tolueno em fase líquida, conduzida num reator Parr do tipo "slurry" à temperatura de 373 K (100 ºC) e sob pressão de H2 de 5 MPa (50 atm). Os resultados obtidos mostram que os catalisadores de Ru/Al2O3 são muito mais ativos que os catalisadores de Ni/Al2O3, sendo ainda seletivos para a obtenção do produto da hidrogenação parcial do tolueno (metilcicloexeno). A maior atividade dentre os catalisadores de Ni/Al2O3 é obtida para um pH de impregnação acima do ponto isoelétrico (pI) do suporte, igual a 6,2, utilizando-se o agente redutor H2CO. No caso dos catalisadores de Ru/Al2O3, o agente H2CO também leva às maiores atividades catalíticas, tendo-se o valor máximo para o pH igual ao pI do suporte. Já o maior rendimento de metilcicloexeno é obtido para o pH igual a 4. Os comportamentos catalíticos observados são analisados e discutidos à luz dos resultados da caracterização dos sólidos e da literatura técnica especializada / Abstract: The hydrogenation of aromatic compounds has been studied due to the wide range of industrial applications, as well as to environmental restrictions imposed by several countries. In this context, the present work aims to study the effects of the impregnation pH and the nature of the reducing agent on the performance of Ni and Ru catalysts supported on ?-Al2O3, employed for toluene hydrogenation in liquid phase. For this, catalysts were prepared from aqueous solution of NiCl3.6H2O and RuCl3.xH2O precursors by wet impregnation, conduced at constant pH between 4 and 8. During impregnation, catalysts were reduced at 353 K (80 ºC) in liquid phase, using formaldehyde (H2CO) or sodium borohydride (NaBH4) as reducing agents. The Ni and Ru catalysts were also reduced under H2 flow at 773 and 573 K (500 and 300 °C) respectively, after the wet impregnation. The support was characterized using the techniques of particle size, N2 adsorption (B.E.T. method) and potentiometric titration. The techniques of SEM+EDX and XPS were used to determine the chemical composition of the employed solids, and the formation of the catalysts active phase was studied by TPR. The catalysts performance were evaluated for toluene hydrogenation reaction in the liquid phase, carried out in a Parr reactor of the slurry type at the temperature of 373 K (100 ° C) and under H2 pressure of 5 MPa (50 atm). The results show that Ru/Al2O3 catalysts are much more active than the Ni/Al2O3 catalysts, and even selective for obtaining the product of the partial hydrogenation of toluene (methylcyclohexene). The highest activity among the Ni/Al2O3 catalysts is obtained by impregnation at pH above of the isoelectric point (pI) of the support, equal to 6.2, using the reducing agent H2CO. In the case of the Ru/Al2O3 catalysts, the H2CO agent also leads to higher catalytic activities, having a maximum value at pH equal to the support pI. However, the highest yield of methylcyclohexene is obtained at pH 4. The observed catalytic behaviors are analyzed and discussed in the light of the results of the characterization of solids and specialized technical literature / Mestrado / Sistemas de Processos Quimicos e Informatica / Mestra em Engenharia Química
173

Avaliação in vitro do ascorbato de sódio em diferentes tempos de aplicação e concentrações na resistência de união à dentina tratada com hipoclorito de sódio e/ou EDTA / In vitro assessment of different times and concentrations of sodium ascorbate on the bond strength to dentin treated with sodium hypochlorite and/or EDTA

Lacerda, Aniele Carvalho, 1983- 02 July 2013 (has links)
Orientador: Caio Cezar Randi Ferraz / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Odontologia de Piracicaba / Made available in DSpace on 2018-08-22T00:09:37Z (GMT). No. of bitstreams: 1 Lacerda_AnieleCarvalho_M.pdf: 1787368 bytes, checksum: 7ae8501ef4c6b79a8032427d280dbdf0 (MD5) Previous issue date: 2013 / Resumo: O objetivo deste estudo foi avaliar in vitro o ascorbato de sódio em diferentes tempos de aplicação e concentrações na resistência de união de um sistema adesivo convencional de 3 passos à dentina da câmara pulpar tratada com hipoclorito de sódio, EDTA ou suas associações. Oitenta e quatro incisivos bovinos hígidos e recém-extraídos foram seccionados, obtendo-se amostra do terço médio vestibular da coroa. As amostras foram distribuídas, aleatoriamente, em 14 grupos (n=6) de acordo com o tratamento superficial da dentina com substâncias químicas. G1(controle): NaCl 0,9%; G2: NaOCl 5,25%; G3 e G4: NaOCl 5,25% seguido de ascorbato de sódio 10 ou 20%, respectivamente, por 10 minutos; G5: NaCl 0,9% seguido de EDTA 17%; G6 e G7: NaCl 0,9% + EDTA 17% seguido de ascorbato de sódio 10 ou 20%, respectivamente, por 10 minutos; G8: NaOCl 5,25% + EDTA 17% + NaOCl 5,25%; G9, G10 e G11 semelhantes ao G8 seguido de ascorbato de sódio 10% por 1, 5 ou 10 minutos, respectivamente; G12, G13 e G14 semelhantes ao G8 seguido de ascorbato de sódio 20% por 1, 5 ou 10 minutos, respectivamente. Ao final, todas as amostras foram imersas em NaCl 0,9% por 3 minutos. A dentina foi hibridizada com Adper Scotchbond Multi-Purpose e, em seguida, preparada para o teste de resistência à microtração. Os dados obtidos foram analisados estatisticamente (? = 0.05) e os padrões de fratura determinados em Microscopia Eletrônica de Varredura (MEV). Os valores de resistência de união do Grupo 1 foram estatisticamente maiores do que os dos demais grupos experimentais, exceto Grupo 4. O Grupo 4 apresentou média superior aos Grupos 9 e 14 (p<0.05). No entanto, não foram verificadas diferenças estatísticas entre os demais grupos, independente do protocolo de tratamento das superfícies dentinárias, tempo de aplicação e concentração do ascorbato de sódio. Concluiu-se que o NaOCl e o EDTA, sozinhos ou associados, reduziram significativamente (p<0.05) os valores de resistência de união na interface resina-dentina da câmara pulpar. O ascorbato de sódio restabeleceu os valores de adesão da dentina da câmara pulpar apenas quando utilizado na concentração de 20% por 10 minutos após o uso isolado de NaOCl (Grupo 4) / Abstract: The aim of this study was to evaluate in vitro the sodium ascorbate in different application times and concentrations on bond strength of a conventional 3 steps adhesive system to the pulp chamber dentin treated with sodium hypochlorite, EDTA or their associations. Eighty-four intact bovine incisors, freshly extracted, were sectioned in order to obtain samples of the buccal middle third of the crown. The samples were randomly distributed into 14 groups (n = 6) according to the chemical surface treatment of the dentin. G1 (control): 0.9% NaCl; G2: 5.25% NaOCl, G3 and G4: 5.25% NaOCl followed by 10 or 20% sodium ascorbate, respectively, for 10 minutes; G5: 0.9% NaCl followed by 17% EDTA; G6 and G7: 0.9% NaCl + 17% EDTA followed by 10 or 20% sodium ascorbate respectively, for 10 minutes; G8: 5.25% NaOCl + 17% EDTA + 5.25% NaOCl; G9, G10 and G11: similar to G8 followed by 10% sodium ascorbate for 1, 5 or 10 minutes, respectively; G12, G13 and G14: similar to G8 followed by 20% sodium ascorbate for 1, 5 or 10 minutes, respectively. At the end, all samples were immersed in 0.9% NaCl for 3 minutes. The dentin was hybridized with Adper Scotchbond Multi-Purpose and then prepared for the microtensile bond strength test. Data were analyzed statistically (?= 0.05) and the failure mode classified under Scanning Electron Microscopy (SEM). The values of bond strength of Group 1 were significantly higher than other groups, except for Group 4. Group 4 showed average superior to Groups 9 and 14 (p <0.05). However, no differences were observed among the other groups, regardless of the dentin surface treatment, application time or concentration of sodium ascorbate. It was concluded that NaOCl and EDTA, whether associated or not, significantly reduced (p <0.05) the bond strength values of resin-dentin interface in the pulp chamber. Sodium ascorbate restored the bond strength values of pulp chamber dentin only when used at a concentration of 20% for 10 minutes after an isolated application of NaOCl on dentin (Group 4) / Mestrado / Endodontia / Mestra em Clínica Odontológica
174

Optimization of the electron donor supply to sulphate reducing bioreactors treating inorganic wastewater / Optimisation de l'approvisionnement en donneur d'électrons pour les bioréacteurs sulfato-réducteurs destinés au traitement des eaux usées inorganiques

Reyes Alvarado, Luis 16 December 2016 (has links)
Une grande quantité des eaux usées, particulièrement celles provenant de l'industrie minière, des fermentations et du traitement des aliments, contiennent-elles des concentrations élevées de sulfate (SO42-). SO42- réduction est une problématique sérieuse au niveau environnemental sous conditions qui ne sont pas contrôlées, cette problématique peut résulter en la libération de sulfure toxique vers l'environnement. Les caractéristiques typiques des eaux usées riches en SO42- sont 0.4-20.8 g SO42-.L-1, faible pH, élevé potentiel oxydatif, faible o négligeable demande chimique d'oxygène (DCO) et hautes concentrations de métaux lourds (drainage minier acide) que peuvent drastiquement endommager la flore et la faune des masses d'eau. L'objectif de cette thèse est d'étudier l'effet du donneur d'électrons sur le processus biologique RS par des bactéries réductrices de sulfate dans des bioréacteurs. Le processus biologique RS a été étudié à l'aide de polymères à base d'hydrate de carbone (PBHC) et biodéchets lignocellulosiques (L) comme des donneurs de libération lente d'électrons (PBCH-DLLE et L-DLLE, respectivement) dans des bioréacteurs discontinus et des bioréacteurs fonctionnant en continu inverse à lit fluidisé (ILF). Les ILF ont été rigoureusement testé pour RS sous haute vitesse et (alimentation-pénurie de nourriture) des conditions d'alimentation transitoires. Dans une autre configuration du bioréacteur, un bioréacteur séquentiel, l'effet de la concentration initiale SO42- sur le démarrage du réacteur a été étudié. Par ailleurs, l'effet de la concentration initiale du donneur d'électrons, NH4+ et SO42- ont été évalués dans des bioréacteurs de traitement par lots aussi bien. La robustesse et la résilience de RS a été démontrée dans les ILF en utilisant le lactate comme donneur d'électrons, dans lequel l'efficacité d'élimination de SO42- (EES) était comparable dans la période d’alimentation (67 ± 15%) de ILF2 aux conditions d'alimentation stables (71 ± 4%) dans même ILF2 et ILF1, le réacteur de commande (61 ± 15%). De la modélisation des réseaux de neurones artificiels et de l'analyse de sensibilité des données de fonctionnement de ILF2, il était prévu que les concentrations de SO42- influents ont affecté le rendement d'élimination de la DCO, la production de sulfure et des changements de pH. Dans un autre ILF3 à un rapport DCO:SO42- de 2.3, RS dans des conditions de taux élevés (CTE = 0.125 d) était 4,866 mg SO42- L-1 d-1 et un EES de 79% a été remporté. Par ailleurs, le second ordre Grau et les modèles d'enlèvement de substrat Stover-Kincannon équipés de la performance du réacteur à haut débit avec r2 > 0.96. Le rapport DCO:SO42- était le principal facteur affectant la RS. Dans des bioréacteurs par lots, en utilisant du papier filtre PBCH-DLLE, la RS a été réalisée à EES > 98%. Avec l'utilisation de scourer comme L-DLLE, un EES de 95% a été remporté. Cependant, lorsque la lavette est utilisée comme matériau de support de L-DLLE dans un ILF4, le RS a montré 38% (± 14) de EES entre 10-33 d de fonctionnement. La SR était limitée par le taux d'hydrolyse-fermentation et, par conséquent, la complexité de la DLLE. L'utilisation du donneur d'électrons pour le processus RS a simultanément amélioré aux concentrations de donneurs d'électrons initial décroissants / Many industrial wastewaters, particularly from the mining, fermentation and food processing industry contain high sulphate (SO42-) concentrations. SO42- reduction (SR) is a serious environmental problem under non-controlled conditions, which can result in the release of toxic sulphide to the environment. Typical characteristics of SO42--rich wastewater are 0.4-20.8 g SO42-.L-1, low pH, high oxidative potential, low or negligible chemical oxygen demand (COD) and high heavy metals concentrations (acid mine drainage), that can dramatically damage the flora and fauna of water bodies. The aim of this PhD is to study the effect of electron donor supply on the biological SR process by sulphate reducing bacteria in bioreactors. The biological SR process was studied using carbohydrate based polymers (CBP) and lignocelulosic biowaste (L) as slow release electron donors (CBP-SRED and L-SRED, respectively) in batch bioreactors and continuously operated inverse fluidized bed bioreactors (IFBB). IFBB were vigorously tested for SR under high rate and transient (feast-famine) feeding conditions. In another bioreactor configuration, a sequencing batch bioreactor, the effect of the initial SO42- concentration on the reactor start-up was investigated. Besides, the effect of the initial concentration of electron donor, NH4+, and SO42- were evaluated in batch bioreactors as well. The robustness and resilience of SR was demonstrated in IFBB using lactate as the electron donor wherein the SO42- removal efficiency (SRE) was comparable in the feast period (67 ± 15%) of IFBB2 to steady feeding conditions (71 ± 4%) in the same IFBB2 and to IFBB1, the control reactor (61 ± 15%). From artificial neural network modeling and sensitivity analysis of data of IFBB2 operation, it was envisaged that the influent SO42- concentrations affected the COD removal efficiency, the sulphide production and pH changes. In another IFBB3 at a COD:SO42- ratio of 2.3, SR under high rate conditions (HRT=0.125 d) was 4,866 mg SO42-. L-1 d-1 and a SRE of 79% was achieved. Besides, the Grau second order and the Stover-Kincannon substrate removal models fitted the high rate reactor performance with r2 > 0.96. The COD:SO42- ratio was the major factor affecting the SR. In batch bioreactors, using filter paper as CBP-SRED, SR was carried out at > 98% SRE. Using scourer as L-SRED, a 95% SRE was achieved. However, when the scourer was used as the L-SRED carrier material in an IFBB4, the SR showed 38 (± 14) % SRE between 10-33 d of operation. The SR was limited by the hydrolysis-fermentation rate and, therefore, the complexity of the SRED. Concerning sequencing batch bioreactor operation, the SR process was affected by the initial SO42- concentration (2.5 g SO42-.L-1) during the start-up. The sequencing batch bioreactor performing at low SRE (< 70%) lead to propionate accumulation, however, acetate was the major end product when SRE was > 90%. In batch bioreactors, the NH4+ feast or famine conditions affected the SR rates with only 4% and the electron donor uptake was 16.6% greater under NH4+ feast conditions. The electron donor utilization via the SR process improved simultaneously to the decreasing initial electron donor concentrations. This PhD research demonstrated that the SR process is robust to transient and high rate feeding conditions. Moreover, SR was mainly affected by the approach how electron donor is supplied, e.g. as SRED or as easy available electron donor, independently of the COD:SO42- ratio. Besides, the electron donor and SO42- utilization were affected by the lack or presence of nutrients like NH4+
175

Zu den gesundheitsfördernden Effekten von Waldaufenthalten / Among the health-promoting effects of forest exposures

Meyer-Schulz, Katharina 25 August 2017 (has links)
No description available.
176

Interactions entre la composition de la ration et les levures vivantes Sc47 (ACTISAF®) : effets sur le statut oxydo-réducteur et l’activité fermentaire dans le rumen chez la vache laitière / Interactions between diet composition and live yeast Sc47 (ACTISAF ®) : effects on redox status and fermentative activity in the rumen of dairy cows

Julien, Christine 04 November 2010 (has links)
L'objectif de ce travail est de caractériser l'effet des levures vivantes Sc47 sur le métabolisme ruminal et l'utilisation digestive de la ration en lien avec le statut oxydo-réducteur du rumen chez des vaches laitières recevant des rations qui diffèrent dans leur composition. En effet, le milieu ruminal est très anaérobie et réducteur : les micro-organismes qui s'y développent sont à l'origine de ces conditions physico-chimiques particulières caractérisées par des valeurs de potentiel rédox (Eh) ou indice de Clark (rH) basses : respectivement dans cette étude entre –213 et –147 mV et entre 6.04 et 7.48 unités rH. L'impact de trois constituants du régime des vaches laitières d'une part sur le statut réducteur du milieu ruminal et d'autre part sur son métabolisme et/ou l'utilisation digestive de la ration a été testé en interaction avec l'addition de levures vivantes : un fourrage sec chez la vache tarie, deux concentrés azotés différant par le niveau de solubilité ruminal des protéines qu'il contient et enfin la nature de l'amidon, rapidement ou lentement dégradable dans le rumen chez la vache en lactation. Il apparaît nettement que le régime alimentaire ainsi que le niveau d'ingestion des animaux influencent directement le statut réducteur du rumen : un niveau réducteur bas étant favorable à l'activité d'une flore cellulolytique alors que des niveaux plus élevés s'avèrent être un indicateur de l'apparition de troubles métaboliques du rumen. En effet, le pouvoir réducteur ruminal est corrélé avec l'activité fermentaire qui s'y développe ainsi qu'à la structure des communautés bactériennes en présence. D'après nos résultats, l'effet de la levure vivante sur les conditions réductrices du rumen semble fortement conditionné par le niveau du statut réducteur induit par le régime alimentaire : les conditions réductrices ruminales peuvent être renforcées dans la mesure où le Eh initial se trouve, dans notre étude, entre –174 et –152 mV. Ce renforcement serait favorable à l'activité de la flore fibrolytique si celle-ci n'est pas dominante, ce groupe fonctionnel participant alors également au maintien des conditons réductrices. En outre, la levure vivante aurait un impact direct sur les bactéries protéolytiques favorisant la quantité de protéines "by pass" si bien que la valeur azotée de la ration peut être améliorée en particulier en termes de PDIA. / The objective of this work is to characterize the effect of live yeast Sc47 on ruminal metabolism and ration digestibility in relation to ruminal redox status of dairy cows fed diets that differed in their composition. Indeed, the rumen environment is very anaerobic and very reducing : the inhabiting micro-organisms are the main sources of particular physic-chemical conditions characterized by low values of redox potential (Eh) or Clark’s exponent (rH): in this study, values were between –213 and –147 mV and between 6.04 and 7.48 units for Eh and rH, respectively. The impact of three constituting ingredients of the diet of dairy cows was investigated. On the one hand, the reducing status of rumen was observed and on the other hand, the metabolism and/or digestibility of the diet with or without addition of live yeast was explored. The tested constituents were: hay for dry dairy cows, two concentrates differing in nitrogen levels of ruminal solubility, and two energetic concentrates differing in rate of ruminal degradation of starch – quickly or slowly degradable in the rumen of lactating dairy cows. It clearly appeared that the diet and the level of dry matter intakes of animals directly influenced the reducing ruminal status: low levels being favorable to the activity of cellulolytic microflora whereas higher levels appeared to be indicators of metabolic disorders occuring in the rumen. Indeed, the reducing power was correlated to rumen fermentative activity and the structure of bacterial communities involved. According to our results, the effect of live yeast on rumen reducing conditions appeared strongly influenced by the level of the intrinsic reducing status induced by diet: reducing conditions in the rumen could be strengthened to the extent that the original values ranged between –174 and –152 mV. This reinforced ruminal conditions would uphold the activity of fibrolytic microflora if it is not dominant, this functional group then participating to the maintenance of reducing conditions. In addition, live yeast has a direct impact on proteolytic bacteria promoting by-pass proteins so that the protein value of the ration may be improved especially in terms of PDIA.
177

Reduzierung der Spieldauer bei Brückenkranen mit überlagerten Bedienbereichen

Könze, Anke, Schulze, Frank 03 April 2018 (has links) (PDF)
Anhand eines Referenzmodells für ein automatisches Lager mit zwei Regalbediengeräten in einer Gasse wurde ein Algorithmus entwickelt, der für einen bekannten Auftragspool eine (Batch-) Optimierung und beim Einsatz von Mehrfachlastaufnahmemitteln zusätzlich eine Tourenoptimierung vornimmt. Die Spiele beider Geräte werden aufeinander abgestimmt, die Spielzeit wird minimiert. Es liegt ein Berechnungswerkzeug vor, mit dem die Spieldauer beim Einsatz von zwei Geräten und überlagerten Bedienbereichen ermittelt werden kann. Die Ergebnisse sind auf automatisierte Brückenkrane mit überlagerten Bedienbereichen übertragbar. Dazu wird ein Anwendungsbeispiel vorgestellt.
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Compréhension des mécanismes physiologiques et génétiques impliqués dans l'activité réductrice de Lactococcus lactis / Understanding of the physiological and genetic mechanisms involved in the reducing activity of Lactococcus lactis

Roussel, Célia 22 June 2015 (has links)
Les bactéries lactiques, en particulier Lactococcus lactis sont utilisées en industrie agroalimentaire. Ces bactéries sont connues pour avoir une activité réductrice, désignant leur aptitude à abaisser le potentiel redox (Eh) d’un milieu. Le génome de L. lactis MG1363 code plusieurs protéines possédant un motif CXXC potentiellement liées à une activité redox. Pour comprendre le rôle des protéines de surface riches en cystéines, deux approches ont été utilisées. Par l’approche bioinformatique, notre intérêt s'est porté sur deux protéines de surface de fonctions inconnues et à motif CX2CX10CX2C : Llmg_0524 et Llmg_0526. Leurs gènes forment un opéron induit temporairement en début de croissance. Dans les deux protéines, le motif chélate un ion de zinc par les résidus cystéines, formant un complexe très stable. Nos données suggèrent que cet opéron contribue à l'intégrité de la paroi cellulaire et que le zinc participe à la stabilité des protéines. L'identification des protéines à thiols exofaciaux par une approche biochimique indique la présente d’AhpF à la surface de L. lactis. La délétion du gène ahpF entraîne une forte sensibilité du mutant au cumène hydroperoxyde, mais aucune au peroxyde d'hydrogène. Le cumène hydroperoxyde provoque une modification de la proportion en acide gras chez le mutant ahpF, le mécanisme de cyclopropanation contribue à sa survie en réponse à un stress oxydatif. La compréhension des fonctions impliquées dans l'activité réductrice des lactocoques permettra une meilleure maîtrise du Eh dans la fabrication des produits fermentés et un meilleur contrôle des flores pathogènes et d’altérations. Le projet Food-Redox a été financé par l'ANR. / Lactic acid bacteria, particularly Lactococcus lactis are used in dairy industry. These bacteria are known to have a reducing activity, indicating their ability to lower the redox potential (Eh) of a medium. L. lactis MG1363 genome encodes several proteins with a CXXC motif, potentially linked with a redox activity. To understand the role of proteins rich in cysteine located at the surface of L. lactis, two approaches were used, one bioinformatics and biochemical another. For bioinformatic approach, interest was focused on two proteins of unknown function and CX2CX10CX2C motif: Llmg_0524 and Llmg_0526. Their corresponding genes form an operon temporarily induces in early growth phase. In these two proteins, the pattern chelate a zinc ion via its cysteine residues. The zinc-cysteine complexe is very stable, it suggests a probable role in protein stability. Data suggest that this operon contributes to the cell wall integrity. The identification of exofacial thiol proteins by a biochemical approach indicates that AhpF is present at the surface of L. lactis. The ahpF gene deletion causes a strong sensitivity to the cumene hydroperoxide, but no sensibility for hydrogen peroxide. In the mutant ahpF incubation with cumene hydroperoxide modified fatty acid proportion, cyclopropanation mechanism thus contributes to the survival in response to oxidative stress. Understanding the lactococci functions involved in the reduction activity allows a better control of redox potentiel in the fermented food production and thus a better control of foodbornes microorganisms in these products. Food-Redox project is financially supported by the French National Research Agency.
179

The comparative effect of two anti-inflammatory diets on Interleukin-6 levels and weight loss in overweight females

Groenewald, Chantell 18 April 2013 (has links)
M.Tech. (Homoeopathy) / Overweight and obesity is an excessive accumulation of fat and can be classified using the body mass index (BMI). Being overweight has a whole host of health-related risks, which includes metabolic syndrome and diabetes mellitus type II to name a few (Goedecke et al. 2005). Interleukin 6 (IL-6), secreted from the adipose tissue surrounding the waist line is responsible for a state of systemic chronic low level inflammation and plays a crucial role in the development of diseases associated with being overweight (Fantuzzi, 2005). Food sensitivities further contributes to this state of low level chronic inflammation. Symptoms of food sensitivities include, difficulty losing weight as well as over eating, which hinders weight loss in over weight individuals (Joyal, 2010). Anti-inflammatory diets such as the Mediterranean diet focuses on a diet rich in antiinflammatory foods, which is known to decrease chronic low level inflammation caused by being overweight and obese. (Galland, 2010). The aim of this study was to determine the comparative effect of the Mediterranean diet to a modified Mediterranean diet (excludes common food sensitivities) on the circulating levels of the inflammatory cytokine interleukin-6 (IL-6) in overweight females by measuring weight loss and IL-6 levels. The study was an experimental comparative study involving thirty female participants who were between the ages of 20-45 and were overweight (BMI 25-30 kg/m²). Potential participants attended an initial interview where they were screened by means of inclusion and exclusion criteria as well as a physical exam that included vitals, weight (kg), waist measurement (cm), hip-to-waist ratio and calculation of BMI. Individuals who met these criteria were sent for blood tests to measure their Interleukin 6 levels (IL-6). Those individuals with an IL-6 level of greater than 0.96pg/ml were then contacted to set up a first appointment. Participants were allocated to either the modified Mediterranean diet or to the Mediterranean diet using matched pairs. Participants attended a three week as well as a 6 week follow up to tract weight-loss progress.
180

Studies On The Bioremoval Of Zinc And Cadmium Using Desulfotomaculum nigrificans

Radhika, V 08 1900 (has links) (PDF)
No description available.

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