Dissertations / Theses: 'Nitrity'

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Machado, Genikelly Cavalcanti. "Determinação sequencial de nitrato e nitrito por voltametria de pulso diferencial empregando um ultramicroeletrodo de ouro." Universidade de São Paulo, 2010. http://www.teses.usp.br/teses/disponiveis/75/75132/tde-20092010-144502/.

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Este trabalho descreve o desenvolvimento de um método eletroanalítico para determinação sequencial de nitrito (NO2-) e nitrato (NO3-), utilizando como técnica, a voltametria de pulso diferencial. O método se baseia na redução eletroquímica dos íons nitrato sobre um ultramicroeletrodo de ouro modificado in situ com cádmio depositado em regime de subtensão, e na seqüência, a remoção da monocamada de cádmio e a oxidação eletroquímica dos íons nitritos sobre o ultramicroeletrodo não modificado. Os ensaios voltamétricos para determinação quantitativa de nitrato e nitrito foram realizados em solução de NaClO4 0,1 molL-1 + HClO4 1,0x 10-3 molL-1 (pH = 3,3) preparada com água ultrapura. Utilizando as condições experimentais e os parâmetros voltamétricos otimizados, foram construídas curvas analíticas para determinação de nitrito e nitrato separadamente e também para determinação sequencial dos dois analitos. Para a determinação do NO2-, foi observado uma relação linear entre a corrente de pico e a concentração desse íon dentro do intervalo de concentração de 1,0 x 10-5 molL-1 a 1,1 x 10-4 molL-1, com um limite de detecção igual a 1,151 ± 0,091 µmolL-1 e limite de quantificação igual a 3,838 ± 0,091 µmolL-1. Para a determinação do NO3-, também foi observado uma relação linear entre corrente de pico e concentração desse analito dentro do intervalo estudado, que foi de 2,00 x 10-5 molL-1 a 2,50 x 10-4 molL-1. O limite de detecção encontrado foi 4,839 ± 0,275 µmolL-1 e o limite de quantificação 16,131 ± 0,275 µmolL-1. A determinação sequencial de nitrito e nitrato foi avaliada dentro do intervalo de concentração de 5,00 x 10-5 molL-1 a 2,50 x 10-4 molL-1 para NO3- e 1,00 x 10-5 molL-1 a 4,50 x 10-5 para NO2-. Para ambos os casos, a relação entre corrente de pico versus concentração do analito foi linear. Para a determinação sequencial os limites de detecção são 16,177 ± 0,794 µmolL-1 para NO3- e 2,243 ± 0,179 µmolL-1 para NO2- e os limites de quantificação são 53,922 ± 0,794 µmolL-1 para o NO3- e 7,476 ± 0,179 µmolL-1 para o NO2-. Os limites de detecção, os limites de quantificação e demais parâmetros estatísticos apresentados nesse trabalho, foram obtidos a partir de cálculos baseados em procedimentos descritos em Miller e Miller68 e Silva69.
This work describes the development of an electroanalytical method for sequential determination of nitrite (NO2-) and nitrate (NO3-), using as a technique, differential pulse voltammetry. The method is based on the electrochemical reduction of nitrate ions on a gold ultramicroelectrode modified in situ by underpotential deposition of cadmium, and subsequently, the removal of cadmium monolayer and the electrochemical oxidation of nitrite on ultramicroelectrode unmodified. The voltammetric analysis for quantitative determination of nitrate and nitrite were carried out in NaClO4 0.1 molL-1 + HClO4 1.0 x 10-3 molL-1 (pH = 3.3) prepared with ultrapure water. Using the optimized experimental conditions and voltammetric parameters, analytical curves were constructed for determination of nitrite and nitrate separately and for sequential determination of the two analytes. The relationship between peak current and concentration of NO2- were found to be linear in the concentration range between 1.0 x 10-5 molL-1 and 1.1 x 10-4 molL-1, with a detection limit of 1.151 ± 0.091 µmolL-1 and quantification limit of 3.838 ± 0.091 µmolL-1. For determination of NO3- was also observed a linear relationship between peak current and concentration of analyte within the concentration range studied, which was from 2.00 x 10-5 molL-1 to 2.50 x 10-4 molL-1. The detection limit was 4.839 ± 0.275 µmolL-1 and the quantification limit was 16.131 ± 0.275 µmolL-1. The sequential determination of nitrite and nitrate was assessed within concentration range from 5.00 x 10-5 molL-1 to 2.50 x 10-4 molL-1 for NO3- and from 1.00 x 10-5 molL-1 to 4.50 x 10-5 for NO2-. In both cases, the relationship between peak current versus analyte concentration were found to be linear. The detection limits for sequential determination are 16.177 ± 0.794 µmolL-1 for NO3- and 2.243 ± 0.179 µmolL-1 for NO2- and the quantification limits are 53.922 ± 0.794 µmolL-1 for NO3- and 7.476 ± 0.179 µmolL-1 for NO2-. The detection and quantification limits and other statistical parameters presented in this work were obtained from calculations based on procedures described in Miller and Miller68 and Silva69.

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Jiquiriçá, Paulo Ricardo Ilha. "Efeitos letais e subletais da poluição por nitrogênio em larvas de anuros." Universidade de São Paulo, 2010. http://www.teses.usp.br/teses/disponiveis/41/41134/tde-13122010-144109/.

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As atividades humanas vêm aumentando dramaticamente a quantidade de nitrogênio inorgânico liberado nos ecossistemas, seja através da aplicação de fertilizantes na agricultura, da descarga de dejetos humanos e de seus rebanhos, ou da queima de combustíveis fósseis. Os excessos de nitrogênio são eventualmente transportados para corpos d´água, onde podem, na forma de nitrato, nitrito e amônio, atingir concentrações tóxicas para organismos aquáticos. Nesta pesquisa tive dois objetivos principais. O primeiro foi testar em laboratório a toxicidade relativa dos íons nitrato, nitrito e amônio, e a variação interespecífica na sensibilidade a esses íons, em larvas de cinco espécies de anuros (Rhinella ornata, Hypsiboas faber, Hypsiboas pardalis, Physalaemus cuvieri e Physalaemus olfersii ). Para isso utilizei bioensaios seguindo protocolos internacionalmente padronizados para testes de ecotoxicidade com organismos aquáticos, e que portanto permitem máximas reprodutibilidade e comparabilidade de resultados entre compostos, espécies, e laboratórios. No entanto, estes bioensaios carecem de realismo uma vez que simulam um cenário de exposição aguda a altas concentrações de contaminantes quando na natureza o cenário de exposição tende a ser crônico e prolongado a baixas concentrações. Além disso, bioensaios usam mortalidade como principal variável de resposta, quando também efeitos subletais podem influenciar a persistência de populações ao modular o sucesso dos indivíduos. Por isso, meu segundo objetivo foi testar em laboratório se concentrações relativamente baixas e ecologicamente relevantes de nitrato, nitrito e amônio podem afetar a sobrevivência, o crescimento, o desenvolvimento e o comportamento das larvas de R. ornata, P. cuvieri e H. faber. Demonstrei através dos bioensaios de exposição aguda que nitrato, a forma mais abundante na natureza, é de baixa toxicidade quando comparada a nitrito e amônio. Demonstrei também que há significativa variação interespecífica na sensibilidade ao nitrogênio inorgânico, e que o ranqueamento de sensibilidade das espécies ao nitrato e ao nitrito foram similares, possivelmente por conta de mecanismos comuns de ação tóxica. Através de experimentos de exposição crônica demonstrei que concentrações relativamente baixas de nitrogênio inorgânico podem causar efeitos letais e subletais às larvas de anuros se houver exposição prolongada. O nitrato causou redução no desenvolvimento larval de P. cuvieri e o amônio na sobrevivência e nas taxas de atividade nos girinos de H. faber. A exposição crônica ao nitrito também reduziu significativamente a sobrevivência das três espécies testadas, o crescimento de H. faber e as taxas de atividade de R. ornata. Contudo, é improvável que as concentrações de nitrito que manipulei em laboratório sejam comuns na natureza, especialmente em condições aeróbicas. Esta pesquisa, além de fornecer importantes informações sobre os possíveis efeitos da poluição por nitrogênio em larvas de anuros, contribui para o avanço da ecotoxicologia no Brasil ao estabelecer as bases para o emprego de espécies nativas de anfíbios como sistema-modelo experimental. Estudos futuros que almejem avaliar o risco ambiental da contaminação por nitrogênio deverão por um lado monitorar concentrações em hábitats naturais e por outro avaliar as consequências das interações sinérgicas entre nitrogênio inorgânico e outros estressores físicos, químicos ou biológicos para larvas de anfíbios.
Human activities dramatically increased the amount of inorganic nitrogen released in ecosystems through the application of fertilizers in agriculture, the generation of human and livestock waste, and the combustion of fossil fuels. This nitrogen eventually reaches water bodies where it can, in the form of nitrate, nitrite and ammonium, be toxic to aquatic organisms. In this study I had two main objectives. The first was to test the relative toxicity of nitrate, nitrite and ammonium, and the interspecific variation in sensitivity to these ions, in tadpoles of five anuran species (Rhinella ornata, Hypsiboas faber, Hypsiboas pardalis, Physalaemus cuvieri and Physalaemus olfersii ). This objective was accomplished by laboratory bioassays following internationally standardized protocols for ecotoxicity tests with aquatic organisms, therefore allowing maximum reproducibility and comparability of results among compounds, species and laboratories. However, these bioassays lack realism for simulating a scenario of acute exposure to high concentrations of contaminants, while exposure in nature tends to be chronic and prolonged at low concentrations. Furthermore, bioassays use mortality as the main response variable, whereas sublethal effects may also influence the persistence of populations by modulating individual success. My second objective was therefore to test in the laboratory if low and environmentally relevant concentrations of nitrate, nitrite and ammonium affect survival, growth, development and behavior of R. ornata, P. cuvieri and H. faber larvae. Through acute exposure bioassays I demonstrated that nitrate, the most abundant N form in nature, has low toxicity when compared to nitrite and ammonium. I also demonstrated that there is significant interspecific variation in the sensitivity to inorganic nitrogen, and that the ranking of species sensitivity to nitrate and nitrite were similar, possibly due to common mechanisms of toxic action. Through chronic exposure I demonstrated that relatively low concentrations of inorganic nitrogen can cause lethal and sublethal effects on anuran larvae if there is extended exposure. Nitrate decreased developmental rate in P. cuvieri and ammonia decreased survival and activity rates in H. faber tadpoles. Chronic exposure to nitrite also significantly reduced survival of all three species tested, growth of H. faber and activity rates of R. ornata. However, it is unlikely that the concentrations of nitrite manipulated in the laboratory are common in nature, especially in aerobic conditions. This is the first study to document deleterious effects of nitrogen pollution to Brazilian amphibian species, and contributes to the development of ecotoxicology in Brazil by establishing the basis for the employment of native amphibians as model experimental system. Future studies that aim to assess the environmental risk of nitrogen contamination should monitor concentrations in natural habitats and evaluate the effects of synergistic interactions between inorganic nitrogen and other physical, chemical or biological stressors to amphibian larvae.

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Pinheiro, Lucas Cézar. "Estudo de mecanismos anti-hipertensivos do nitrito de sódio na hipertensão renovascular experimental." Universidade de São Paulo, 2014. http://www.teses.usp.br/teses/disponiveis/17/17133/tde-18032015-230532/.

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O NO regula diversos sistemas orgânicos. No sistema cardiovascular participa ativamente na regulação do tônus vascular entre outras funções. Disfunções na produção ou disponibilidade de NO podem comprometer sua atuação fisiológica. No âmbito vascular isto pode participar da hipertensão. Além da produção de NO pelas óxido nítrico sintases, outras vias paralela de produção fisiológica de NO a partir do nitrito tem sido descritas. O nitrito é o produto inicial da oxidação do NO, sendo posteriormente oxidado a nitrato. Sabe-se que estas três moléculas formam um ciclo dentro do organismo, onde o nitrato é excretado na saliva e convertido a nitrito pelas bactérias bucais.Este nitrito é deglutido com a saliva e exerce seus efeitos, através da conversão a NO. A conversão de nitrito a NO pode ocorrer de forma enzimática ou não enzimática. Como forma não enzimática, o nitrito é convertido a NO pela reação com H+. Esta redução ocorre principalmente no estômago. Esta tese visa elucidar possíveis mecanismos responsáveis pelos efeitos anti-hipertensivos do nitrito de sódio. Avaliamos ratos 2 rins 1 clipe (2R1C) tratados com nitrito e nitrato e verificamos os efeitos anti-hipertensivo destes. De forma Interessante, o aumento do pH gástrico com omeprazol impediu o efeito anti-hipertensivo tanto do nitrito quanto do nitrato. O omeprazol não gerou qualquer diferença na concentração plasmática de nitrito e nitrato. Foi verificado que o tratamento com nitrito e nitrato resultou em aumento das espécies nitrosiladas no plasma e este aumento foi impedido pelo omeprazol. Também testamos a influência do ciclo entero-salivar no efeito do nitrito e nitrato. Verificamos que o tratamento com enxaguante bucal levou ao bloqueio do efeito anti-hipertensivo do nitrato, mas não alterou este efeito nos animais tratados com nitrito. Em todas as abordagens experimentais o efeito anti-hipertensivo do nitrito apenas ocorreu quando houve aumento da concentração plasmática de espécies nitrosiladas.
Nitric Oxide plays many functional roles in physiological systems. In the cardiovascular system it participates in a unique way in the regulation of vascular tone among other functions. Dysfunctions in the production or availability of NO may compromise their physiological activity and participate in hypertension. Besides the production of NO by the nitric oxide synthase, other physiological pathways of NO production from nitrite have been described. The nitrite and nitrate are oxidation products of NO. Further nitrite is oxidized to nitrate. These three molecules are known to forma cycle in the body. Nitrate is excreted in saliva and reduced to nitrite by oral bacteria. Nitrite then is swallowed with the saliva and exerts its effects through conversion to NO. The conversion of nitrite to NO may occur by enzymatic or non-enzymatic manner. As a non-enzymatic way nitrite is reduced to NO by reaction with H+.This reaction occurs mainly in the stomach. This thesis aims to elucidate possible mechanisms responsible for the antihypertensive effects of sodium nitrite. We studied 2K1C rats treated with nitrite and nitrate and checked anti-hypertensive effects of these molecules. The increased gastric pH by omeprazole prevented the anti-hypertensive effect of nitrite and nitrate. Omeprazole did not cause any differences in plasma nitrite and nitrate. It was found that treatment with nitrite and nitrate resulted inincreased nitrosylated species in the plasma, and this increase was blocked by omeprazole. We also tested the influence of the entero-salivarycycle effect of nitrite and nitrate. We found that treatment with mouthwash blunted the antihypertensive effect of nitrate but this effect did not change in animals treated with nitrite. Interestingly in all experimental approaches the anti-hypertensive effect of nitrite only occurred when there was an increase in the plasma concentration of nitrosylated species

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Petersson, Joel. "Nitrate, Nitrite and Nitric Oxide in Gastric Mucosal Defense." Doctoral thesis, Uppsala University, Department of Medical Cell Biology, 2008. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-8624.

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The human stomach normally contains high levels of bioactive nitric oxide (NO). This NO derives from salivary nitrate (NO₃^-) that is converted to nitrite (NO₂^-) by oral bacteria and thereafter non-enzymatically reduced in the acidic gastric lumen to NO. Nitrate is a common component in vegetables, and after ingestion it is absorbed in the small intestine. Interestingly, circulating nitrate is then concentrated by the salivary glands. Hence, intake of nitrate-rich vegetables results in high levels of NO in the stomach. The physiological effects of the high concentration of NO gas normally present in the gastric lumen have been hitherto unknown, and the present investigations were therefore conducted to address this issue.

NO produced in the gastric lumen after nitrate ingestion increased gastric mucosal blood flow and the thickness of the firmly adherent mucus layer in the stomach. The blood flow and mucus layer are essential defense mechanisms that protect the mucosa from luminal acid and noxious agents. Nonsteroidal antiinflammatory drugs (NSAID) are commonly prescribed and effective drugs for treating pain and inflammation, but are associated with severe gastrointestinal side effects. We demonstrated that a nitrate-rich diet protects against NSAID-induced gastric damage, as a result of the increased formation of NO in the stomach. We also showed that the gastroprotective effect attributed to nitrate depended completely on conversion of nitrate to nitrite by the bacterial flora colonizing the tongue, and that the oral microflora is therefore important in regulating physiological conditions in the stomach.

In summary, this thesis challenges the current dogma that nitrate intake is hazardous, and on the contrary suggests that dietary nitrate plays a direct role in regulating gastric homeostasis. It is likely that a sufficient supply of nitrate in the diet together with the oral microflora is essential for preventing pathological conditions in the gastrointestinal tract.

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Castro, Leonidia Maria de. "Interferência dos metais zinco, chumbo e cobre, no processo de nitrificação no tratamento de efluentes de uma indústria química: estudo de caso." Universidade de São Paulo, 2001. http://www.teses.usp.br/teses/disponiveis/18/18138/tde-27012017-162144/.

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Durante o estudo de um sistema de tratamento de efluentes de uma indústria química, contendo em suas águas residuárias vários metais pesados foi observada a ineficiência no processo de nitrificação do efluente tratado. Diante dessa constatação, desenvolveu-se este trabalho visando estudar as interferências dos metais pesados, Pb2+, Zn2+ e Cu2+ no desempenho do processo de nitrificação em um sistema similar de tratamento. Para observação dos efeitos dos metais Zn2+, Pb2+ e Cu2+ isoladamente, foram montados 3 reatores e simuladas as concentrações afluentes do tanque de aeração da indústria. Outros três reatores alimentados com soluções contendo Zn+Cu, Zn+Pb e Pb+Cu utilizados para observação de possíveis efeitos de sinergismo e antagonismo. Um outro reator foi alimentado com a solução dos três metais (Zn2+, Cu2+ e Pb2+). Todos os reatores, recebendo adição de metal ou não, apresentaram concentrações muito elevadas de nitrito. Na realização do ensaio de NMP ficou evidente a inibição dos organismos oxidantes de nitrito, que pode ter ocorrido pela alta concentração do próprio nitrito, ácido nitroso ou amônia livre. Efeitos dos metais Zn2+ e Cu2+ não foram evidentes, o Pb2+ foi o único metal que apresentou efeito de inibição no processo de nitrificação. Os reatores que receberam combinação de íons metálicos não evidenciaram efeitos de sinergismo nem antagonismo, sendo que o reator que recebeu adição dos três íons apresentou menor eficiência.
During the study of the chemical industry effluent treatment system containing, several heavy metals, was observed an inefficiency in the nitrification process in final effluent. Therefore, this work was deve!oped to find out ofthe study of the interference of the heavy metals, Pb2+, Zn2+ and Cu2+ on the performance of nitrification process in a similar system of treatment. For observation of the effects of metals Zn2+, Pb2+ and Cu2+ separately, were established three reactors and simulate the influent concentration in the aeration tank of the industry. Other three reactors were fed with solution containing Zn+Cu, Zn+Pb and Pb+Cu for observation of possible synergism or antagonism effects. The other reactor was fed with a solution of the three metals (Zn2+, Cu2+ and Pb2+). All the reactors, receiving the addition of metaIs or not, presented very high concentrations of nitrite. In the realization of the test of NMP, the inhibition of the nitrite oxidizers organisms was evident, that might have happened due to high concentration of nitrous acid, free ammonia and nitrite. The effects of the metals Zn2+ and Cu2+ were not evident; but the Pb2+ was the only metal that presented inhibition effect in the nitrification process. The reactors that received the metallic ion combination didn\'t evidence neither synergism nor antagonism effects, however the reactor that received the addition of the three ions presented smaller efficiency.

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Bescós, García Raúl. "The effect of nitric oxide donors on human performance." Doctoral thesis, Universitat de Barcelona, 2011. http://hdl.handle.net/10803/62896.

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Nitric oxide or nitrogen monoxide (NO) is a tiny free radical gas. The discovery of this intriguing molecule has revolutionized physiology and pharmacology research during the last 20 years. Currently, it is known that NO is endogenously synthesized by several molecules and tissues via two pathways: the synthase-dependent pathway and the synthase-independent pathway. In the first, the amino acid L-arginine is the main donnor of NO synthesis. In the second, inorganic nitrate is the main substrate for the synthesis of this molecule. Interestingly, both pathways are directly connected. While the synthase-dependent pathway is oxygen dependent, the synthase-independent metabolic route is greatly facilitated under hypoxia conditions. Thus, these mechanisms of NO production regulate levels of NO in the tissues. An adequate production of NO is important because it plays an essential role in mechanisms related with vasodilatation and blood flow distribution. Additionally, NO modulates other important functions in the human body such as mitochondrial respiration and immune mechanisms. For all these reasons, the interest for dietary NO donors have increased during the last years. It has been suggested that the consumption of food rich in L-arginine or in inorganic nitrate may enhance NO availability in the human body. This hypothesis has not been unnoticed in exercise physiology. In fact, it has been suggested that supplementation with NO donors may improve the cardio-respiratory response, as well as the tolerance to endurance exercise in humans. However, there is a lack of studies analyzing this issue. Therefore, the aim of this doctoral thesis was to assess the effect of L-arginine and inorganic nitrate in the cardio-respiratory and metabolic response of healthy humans. To develop this aim, three studies and one review were carried out. In the first, it was found that L-arginine supplementation during three days at several doses, between 5.5 and 20.5 g/day was not effective to increase plasma markers of NO, as well as the cardio-respiratory and metabolic response during endurance test. In the second study we found that acute dose of inorganic nitrate supplementation (10 mg/kg of body mass) raised significantly plasma levels of nitrate and nitrite. However, this effect did not report an improvement in the cardio-respiratory response at low-to-moderate intensities of exercise. However, at maximal work loads of exercise dietary nitrate induced significantly reduction of oxygen consumption (VO2peak) compared with placebo. Other cardio-respiratory parameters, as well as blood lactate concentration did not differ between nitrate and placebo. In addition, exercise performance measured as time to exhaustion during an incremental test did not increase compared with placebo. All these findings together suggested that at higher intensities of exercise energy production became more efficient after inorganic nitrate ingestion. Accordingly, in the third study it was analyzed the effect of dietary inorganic nitrate ingestion for three days during endurance exercise in a cycle ergometer at high intensity (time-trial of 40-min). Results of this study showed that nitrate supplementation did not increase significantly plasma levels of nitrite, as well as enhance performance in healthy subjects. Interestingly, a significant, negative correlation was found between change in nitrite and endurance capacity measured as VO2peak during the exercise test. These results indicated that the effect of dietary nitrate ingestion was lower in subjects with high cardiovascular capacity compared with subjects with poor tolerance capacity to endurance exercise. This fact is very important, since it is known that endurance training increase values of VO2peak in sedentary population and this fact is correlated with lower incidence of cardiovascular diseases. These and other important conclusions of these studies are included in the last work of this thesis which was a review article.
L’òxid nítric (NO) es un radical lliure alliberat per diverses molècules i teixits en l’organisme humà. El descobriment d’aquesta intrigant molècula ha revolucionat la recerca en el camp de la fisiologia i la farmacologia durant els últims 20 anys. Actualment, es coneix que la alliberació de NO per part de les cèl•lules endotelials estimula el procés de vasodilatació. A més, també es coneix que aquesta molècula es un important regulador de la respiració mitocondrial i del sistema immunològic. Totes aquestes funcions han generat un gran interès per els precursors nutricionals de NO. En l’àmbit de la fisiologia de l’exercici físic s’ha suggerit que la suplementació amb alguna d’aquestes substancies (L-arginina o nitrat inorgànic) pot millorar la tolerància a l’exercici físic de resistència. No obstant, hi ha molta controvèrsia en els resultats dels estudis que han analitzat aquesta hipòtesi. Per tant, l’objectiu principal d’aquesta tesi doctoral va ser analitzar els efectes dels principals precursors de NO, L-arginina i nitrat inorgànic, en la resposta cardiorrespiratòria i metabòlica durant l’exercici físic de caràcter aeròbic en humans. Per dur a terme aquest objectiu es van realitzar 3 estudis i una revisió bibliogràfica. Els principals resultats d’aquests estudis van mostrar que la suplementació de L-arginina en diferents dosis no va ser efectiva per augmentar el marcadors plasmàtics de NO, així com, la resposta cardiorrespiratòria i metabòlica durant un exercici físic aeròbic en intensitats moderades. En referència als nitrat inorgànic, es va observar que la suplementació augmenta els nivells d’aquests compostos en plasma. No obstant, aquest fet no es va correlacionar amb una millora de la tolerància a l’exercici físic de resistència. A més, es va observar una correlación negativa i significativa entre l’augment dels nitrits plasmàtics i la potència aeròbica màxima (VO2max). Tots aquests resultats van ser àmpliament tractats en l’últim treball (revisió bibliogràfica) d’aquesta tesi. En resum, l’ingesta nutricional de L-arginina i/o nitrat inorgànic no resulta efectiva per millorar la resposta cardiorrespiratòria i la tolerància a l’exercici físic de resistència en humans sans i entrenats físicament.

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Melchert, Wanessa Roberto. "Desenvolvimento de procedimentos analíticos limpos em sistemas de análises em fluxo para determinação de espécies de interesse ambiental." Universidade de São Paulo, 2005. http://www.teses.usp.br/teses/disponiveis/46/46133/tde-20102006-084230/.

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A química limpa tem como principal objetivo o desenvolvimento e a implementação de processos e produtos químicos para reduzir ou eliminar o uso ou a geração de substâncias nocivas à saúde humana e ao meio ambiente. Neste trabalho, foram desenvolvidos procedimentos analíticos limpos para a determinação de nitrato e nitrito em águas naturais e para o tratamento dos resíduos gerados na determinação espectrofotométrica de nitrito e fenóis. Para tanto, foram exploradas as principais estratégias empregadas em química limpa: substituição dos reagentes tóxicos, minimização do consumo dos reagentes e dos resíduos gerados e tratamento desses resíduos. O procedimento analítico limpo para a determinação de nitrato em águas naturais foi baseado em medidas diretas no ultravioleta, após separação de nitrato dos interferentes utilizando um sistema de análises em fluxo com coluna de resina aniônica. O método desenvolvido emprega um único reagente (HClO4) em quantidades mínimas (18 µL/determinação) e permite a determinação de nitrato entre 0,50 e 25,0 mg L-1, sem interferência de ácido húmico, NO2-, PO43-, Cl-, SO42- e ferro(III) nas quantidades usuais em águas naturais. A freqüência de amostragem e o coeficiente de variação (n = 20) foram estimados em 17 determinações h-1 e 0,7%, respectivamente. Os resultados obtidos para amostras de águas de diferentes procedências foram concordantes com o método de referência (redução a nitrito por limalhas de cádmio cobreado seguida por reação de diazo-acoplamento) a nível de confiança de 95%. O tratamento do resíduo gerado na determinação de nitrito, empregando irradiação (UV) na presença do reagente de Fenton (80 mmol/L H2O2 e 1 mmol/L Fe2+), promoveu completa descoloração do resíduo com diminuição de ca. 87% na concentração de carbono orgânico total. A fotodegradação também foi aplicada no tratamento do resíduo gerado na determinação de fenóis totais com 4-aminoantipirina. A degradação ocorreu na presença de H2O2 e irradiação (UV). A completa supressão da absorção de radiação pela 4-aminoantipirina foi observada após 30 min de recirculação da solução no foto-reator, à vazão de 4 mL/min. O procedimento analítico para a determinação de nitrito foi baseado em sistema de análises em fluxo com multicomutação empregando mini-bombas solenóides para o gerenciamento das soluções. O sistema foi acoplado a um foto-reator para a degradação em linha dos resíduos gerados. O método desenvolvido minimiza as quantidades de reagentes (0,6 mg sulfanilamida e 0,03 mg N-naftil-etilenodiamina por determinação) e permite a determinação de nitrito entre 0,10 e 1,00 mg L-1 (r = 0,998) com sensibilidade comparável à alcançada no procedimento com adição contínua de reagentes. O limite de detecção (99,7% de confiança), coeficiente de variação (n = 20) e freqüência de amostragem foram estimados em 17 µg L-1, 2,6% e 80 determinações h-1, respectivamente.
Green chemistry has as principal objective the development and implementation of chemical processes and products to minimize or eliminate the use or generation of harmful substances to the human health and the environment. In this work, clean analytical procedures for determination of nitrate and nitrite in natural waters and for the treatment of wastes generated in the spectrophotometric determination of nitrite and phenol were developed. The principal strategies employed in green chemistry were explored to achieve these goals: replacement of the toxic reagents, minimization of reagent consumption and waste generation and waste treatment. The clean analytical procedure for nitrate determination in natural waters was based on the direct spectrophotometric measurement in the ultraviolet, after separation of nitrate from interfering species in a flow-injection system with an anion-exchange resin. The developed method employ only one reagent (HClO4) in minimum amount (18 µL/determination) and can be applied for nitrate determination within 0.50 and 25.0 mg L-1, without interference of humic acid, NO2-, PO43-, Cl-, SO42- and iron(III) in concentrations typically found in natural waters. The sampling rate and the coefficient of variation (n = 20) were estimated as 17 determinations per hour and 0.7%, respectively. Results obtained for natural water samples of different origin were in agreement with the reference method (reduction to nitrite by copperized cadmium filings followed by a diazo-coupling reaction) at the 95% confidence level. The treatment of the waste generated in nitrite determination employing UV irradiation in the presence of Fenton reagent (80 mmol/L H2O2 and 1 mmol/L Fe2+) caused the complete discoloration of the waste and reduced the total organic carbon concentration in 87%. The photodegradation was also applied for the treatment of the waste generated in the determination of total phenols with 4-aminoantipyrine. The degradation occurred in the presence of H2O2 and UV irradiation. Radiation absorption by 4-aminoantipyrine was completely suppressed after 30 min of treatment of solution in the recirculation mode at 4mL/min. The analytical procedure for nitrite determination was based on a flow system with multicommutation employing solenoid micro-pumps for the solution handling. The developed method minimizes the reagent amounts (0.6 mg sulfanilamide and 0.03 mg N-(1-Naphthyl)-ethylene-diamine per determination) and can be applied for nitrite determination within 0.10 and 1.00 mg L-1 (r = 0.998) with sensitivity comparable to the achieved in the procedure with continuous reagent addition. The detection limit (99.7% of confidence), coefficient of variation (n = 20) and sampling rate were estimated as 17 µg L-1, 2.6% and 80 determinations per hour, respectively.

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Ferreira, Paulo Eduardo Gomes. "Efeito de um programa pré-operatório de fortalecimento supervisionado da musculatura inspiratória na evolução hospitalar de pacientes submetidos a operações cardíacas." Universidade de São Paulo, 2013. http://www.teses.usp.br/teses/disponiveis/17/17137/tde-05042013-230022/.

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Introdução: A disfunção respiratória é uma das complicações mais frequentes após operações cardíacas. Vários fatores contribuem para que as disfunções respiratórias ocorram, dentre eles está a disfunção da musculatura inspiratória que, por sua vez, pode ser multifatorial. Objetivo: O condicionamento da musculatura inspiratória no período pré-operatório poderia ajudar a reduzir a incidência de complicações respiratórias no pós-operatório de operações cardíacas. Métodos: No presente trabalho 21 pacientes voluntários, de ambos os sexos, com idade mínima de 50 anos, com fraqueza de musculatura inspiratória e candidatos à operação de revascularização cirúrgica do miocárdio e/ou operação valvar cardíaca no Hospital das Clínicas da Faculdade de Medicina de Ribeirão Preto-USP foram distribuídos aleatoriamente em 2 grupos. Em um grupo, 10 pacientes foram submetidos a um período mínimo de 9 dias de treinamento da musculatura inspiratória utilizando um incentivador respiratório marca Threshold® IMT (Respironics, Cedar Grove, NJ, EUA), com carga de 40, 60 e 80% da pressão inspiratória máxima. Os outros 11 pacientes receberam apenas orientações gerais, sem treinamento objetivo da musculatura respiratória. Comparamos os valores espirométricos antes e após o treinamento dentro de cada grupo. A evolução da pressão inspiratória máxima, da pressão expiratória máxima e da gasometria arterial de ambos os grupos, antes e após o treinamento, bem como a sua evolução temporal no pós-operatório, além dos valores de nitrito/nitrato no condensado do exalado pulmonar. Comparamos também a evolução clínica de ambos os grupos. Resultados: Observamos que o treinamento causou elevação significativa do pico de fluxo expiratório (p=0,028) e diminuição nos valores de nitrito/nitrato no condensado do exalado pulmonar (p=0,05) e redução das complicações pós operatórias (p=0,057), sendo as duas últimas não significativas. Todavia, não houve diferença na evolução gasométrica e nem da pressão inspiratória máxima ou da pressão expiratória máxima entre ambos os grupos. Conclusão: O treinamento da musculatura respiratória inspiratória em pacientes internados, além de factível e seguro, resulta em maior fortalecimento dessa musculatura, reduz a morbidade pós-operatória e os níveis de nitrito/nitrato no condensado do exalado pulmonar
Introduction: Respiratory dysfunction is one of the most common complications after cardiac operations. Several factors contribute to respiratory dysfunctions that occur among them is inspiratory muscle dysfunction that, in turn, may be multifactorial. Objective: The conditioning of inspiratory muscles on preoperative could help reduce the incidence of respiratory complications in the postoperative period of cardiac operations. Methods: In this study 21 patients volunteers of both sexes, aged 50 years, with weakness of inspiratory muscles and candidate operation of CABG and / or heart valve surgery at the Hospital of the Medical College of Ribeirão Preto-USP were randomized into 2 groups. In one group, 10 patients underwent a minimum of 9 days of inspiratory muscle training using an incentive spirometry \"Threshold® IMT\" (Respironics, Cedar Grove, NJ, USA) with a load of 40, 60 and 80% of maximal inspiratory pressure. The other 11 patients received only general guidelines without respiratory muscle training goal. We compared spirometric values before and after training within each group. The evolution of maximal inspiratory pressure, maximal expiratory pressure and arterial blood gas analysis of both groups before and after training, as well as its temporal evolution postoperatively, and the values of nitrite / nitrate in exhaled breath condensate. We also compared the clinical outcomes in both groups. Results: We observed that the training caused significant peak expiratory flow (p=0,028) and decrease in nitrite/nitrate in exhaled breath condensate (p=0,05) and reduction of postoperative complications (p=0,057), the last two being non-significant. However, there was no difference in blood gas evolution nor maximal inspiratory pressure and maximal expiratory pressure between both groups. Conclusion: The inspiratory muscle training in patients hospitalized, and feasible and safe, results in further strengthening these muscles, reduces postoperative morbidity and levels of nitrite / nitrate in exhaled breath condensate

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Bernardo, Patrícia Ramalheiro. "Caracterização de perigos químicos em enchidos curados tradicionais : nitrosaminas e seus precursores." Master's thesis, Universidade de Lisboa, Faculdade de Medicina Veterinária, 2021. http://hdl.handle.net/10400.5/21238.

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Dissertação de Mestrado em Segurança Alimentar
O salpicão é um enchido curado tradicional português, que pertence a um vasto grupo de produtos cárneos. Para além de representarem parte da dieta mediterrânica, estes produtos são importantes para as economias rurais e para a preservação da herança. No entanto, em 2015, a IARC avaliou a carcinogenicidade do consumo de carne processada. Como resultado, a carne processada foi classificada como carcinogénica para humanos (Grupo 1), com base em evidência suficiente de que o consumo de carne processada causa cancro colorretal. As N-nitrosaminas inserem-se no grupo das substâncias responsáveis por este efeito carcinogénico. Desta forma, é importante saber se estes compostos estão presentes nos produtos cárneos, particularmente no salpicão. Mais ainda, é importante perceber se estão reunidas as condições para a sua formação, nomeadamente precursores e ambiente ácido. Por estes motivos, analisaram-se amostras de salpicão, de três unidades fabris distintas, quanto aos teores de nitratos, nitritos, aminas secundárias e N-nitrosaminas. Também o pH das amostras foi analisado. As análises químicas foram efetuadas nos seguintes pontos temporais: carne (T0), pré-enchimento (T1), meia cura (T2), produto final (T3), meio do prazo de validade (T4) e final do prazo de validade (T5). Os valores de pH variaram entre 5,6 e 5,8 na carne (T0) e mantiveram-se dentro da gama esperada para produtos fermentados. Não se detetaram nitratos (acima do Limite de Quantificação). Quanto à determinação de nitrito residual, apenas se detetaram (acima do Limite de Quantificação) nas amostras da unidade fabril C, mas sempre em teores muito inferiores ao permitido na legislação da EU (100 mg NaNO2/kg). Não se detetaram aminas secundárias nas amostras da unidade fabril B. Detetaram-se aminas secundárias em algumas amostras da unidade fabril A (T1 e T5) e da unidade fabril C (T0, T1 e T5), sendo que os valores médios mais elevados foram: 7,4 mg de Piperdina/kg, 11,0 mg de Di-n-propilamina/kg, 20,9 mg de Pirrolidina/kg, 22,6 mg de Morfolina/kg e 26,2 mg de Dimetilamina/kg. Não se detetaram nitrosaminas nas amostras analisadas. Apesar de existir uma válida preocupação em torno das N-nitrosaminas, estes compostos não foram detetados nos produtos em estudo, nem os seus precursores em concentrações suficientes, para a sua formação. É necessário continuar a estudar este assunto para que se consiga compreender a relação entre o consumo de diferentes tipos de carne processada e o verdadeiro risco para a saúde do Homem.
ABSTRACT - Characterization of chemical hazards in traditional cured meat sausages: nitrosamines and precursors - “Salpicão” is a traditional Portuguese cured sausage, and it belongs to a wide group of meat products. These products not only represent part of the Mediterranean diet, but also have great value for the economy of rural areas and for the preservation of heritage. However, in 2015, IARC has evaluated the carcinogenicity associated to the consumption of processed meat. As a result, processed meat was classified as carcinogenic to humans (Group 1), based on sufficient evidence that the consumption of processed meat causes colorectal cancer. N-nitrosamines are among the responsible substances for the assessed carcinogenic effect. Therefore, there is a need to understand if these compounds are present in meat products, particularly in “salpicão”. Moreover, it is also important to know if the combination of precursors and acidic environment are gathered, to generate N-nitrosamines. For this purpose, samples of “salpicão”, from three distinct factories, were analysed for the quantification of nitrate, nitrite, secondary amines, and N-nitrosamines levels. The pH levels were also evaluated. The chemical analyses and pH evaluation were performed at the following time points: raw meat (T0), before stuffing (T1), middle of curing process (T2), finished product (T3), middle of shelf-life (T4), and end of shelf-life (T5). The pH values of all meat samples ranged between 5,6 and 5,8 and remained within the expected for fermented products. No residual nitrate levels were found to be above the Limit of Quantification. As for residual nitrite levels, those were only detected (above Limit of Quantification) in the samples from factory C, but always considerably under the legal EU limit (100 mg NaNO2/kg). No secondary amines were detected in the samples from factory B. Secondary amines were detected in few samples of the factory A (T1 and T5) and factory C (T0, T1 and T5), with the highest mean values of 7,4 mg of Piperdine/kg, 11,0 mg of Dipropylamine/kg, 20,9 mg of Pyrrolidine/kg, 22,6 mg of Morpholine/kg and 26,2 mg of Dimethylamine/kg. No nitrosamines were detected in the analysed samples. Although nitrosamines may be substances of great concern, they were not found in these meat products, nor their precursors, in sufficient concentrations. Further studies are required to fully understand the link between the consumption of different kinds of processed meat and the actual risk that they represent to human health.
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Ré, Ana de Almeida. "Aplicação de infusões de ervas aromáticas para substituição de aditivos químicos num modelo de carne fermentado." Master's thesis, Universidade de Lisboa, Faculdade de Medicina Veterinária, 2020. http://hdl.handle.net/10400.5/20364.

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Dissertação de Mestrado Integrado em Medicina Veterinária
Atualmente, existe uma procura crescente por conservantes naturais, sobretudo de origem vegetal, para reduzir o conteúdo de nitrito e/ou nitrato (aditivos químicos) em produtos curados à base de carne. Com este trabalho pretendeu-se estudar formas de substituir o uso destes aditivos químicos por infusões de quatro ervas aromáticas (Manjericão Rubra, Tomilho Limão, Orégãos vulgar e Sálvia Ananás), como fonte natural de nitrato, avaliando a evolução da microbiota tecnológica, características físico-químicas e sensoriais (baseado numa escala Just about right), num modelo cárneo armazenado em refrigeração durante quatro dias. Foram realizadas seis formulações, com diferentes concentrações de nitrato de sódio (mg) por quilograma de produto cárneo, correspondentes a: (C) Controlo com 0 ppm; (T1) Manjericão rubra com 70 ppm; (T2) Tomilho limão com 70 ppm; (T3) Manjericão rubra com 100 ppm; (T4) Sálvia ananás com 100 ppm; (T5) Orégãos com 100 ppm. Os modelos cárneos foram analisados realizando-se contagens de Aeróbios totais a 30 ºC, Enterobacteriaceae, Bactérias Ácido Lácticas (BAL) e Staphylococcus coagulase negativa (SCN). Foram ainda determinados os teores de nitratos, nitritos, cloretos, a cor e o pH. As infusões com sálvia ananás mostraram ter um maior conteúdo de nitrato (63.124 mg/100ml) em comparação com infusões de tomilho limão e orégãos. O modelo cárneo T4 apresentou uma maior quantidade de nitratos (média 16.91 mg/kg). Este produto modelo após um período de 2 para 4 dias de armazenamento a 4 ºC, apresentou valores de nitrito de 3.93 mg/kg, onde se observou que a cor após cozedura teve um aumento da coordenada a* no dia 4, demonstrando uma cor mais rosada/avermelhada, indicativo do desenvolvimento do nitrosohemocromogénio. Além disso na caracterização sensorial do produto modelo não se notou nenhum aroma a ervas ou especiarias, exibindo sabores e cheiros neutros. Estes resultados indicam que os ingredientes naturais, como a infusão de sálvia ananás, podem ser possivelmente utilizados como alternativa a aditivos químicos na cura tradicional. Contudo, é necessária mais investigação para avaliar o impacto sensorial e microbiológico deste ingrediente quando utilizado em produtos curados à base de carne com novas formulações e com a adição de novos condimentos.
ABSTRACT - Application of aromatic plants infusions to replace chemical additives in a fermented meat model - Currently, there is an increasing demand for natural preservatives, mainly of vegetable origin, to reduce the content of nitrite and/or nitrate (chemical additives) in cured meat products. This work aimed to study ways to replace the use of these chemical additives by infusions of four aromatic plants (Red Basil, Lemon Thyme, Common Oregano and Pineapple Sage), as a natural source of nitrate, evaluating the evolution of technological microbiota, physical-chemical and sensory characteristics (based on a Just about right scale), in a meat model stored in refrigeration for four days. Six formulations were performed, with different concentrations of sodium nitrate (mg) per kilogram of meat product, corresponding to (C) 0 ppm control; (T1) 70 ppm red basil; (T2) 70 ppm lemon thyme; (T3) 100 ppm red basil; (T4) 100 ppm pineapple sage; (T5) 100 ppm common oregano. The meat models were analysed by performing total Aerobic counts at 30 ºC, Enterobacteriaceae, Lactic Acid Bacteria (BAL) and Staphylococcus coagulase negative (SCN). The levels of nitrates, nitrites, chlorides, colour and pH were also determined. Pineapple Sage infusions showed a higher nitrate content (63,124 mg/100ml) compared to lemon thyme and common oregano infusions. The T4 meat model showed a higher nitrate content (mean 16.91 mg/kg). This model product after a period of 2 to 4 days of storage at 4 ºC, showed nitrite values of 3.93 mg/kg, where it was observed that the colour after cooking had an increase of the a* coordinate on day 4, showing a pinker/redder colour, indicative of the development of nitrosohemochromogen. In addition, the sensory characterization of the model product did not show any herbs or spices aroma, presenting neutral flavours and smells. These results indicate that natural ingredients, such as pineapple sage infusion, can possibly be used as an alternative to chemical additives in traditional curing. However, further research is needed to assess the sensory and microbiological impact of this ingredient when used in cured meat products with new formulations and the addition of new condiments.
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Lízalová, Martina. "Aplikace vybraných metod k analýze oxidačního stresu." Doctoral thesis, Vysoké učení technické v Brně. Fakulta chemická, 2010. http://www.nusl.cz/ntk/nusl-233302.

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Chronic pancreatitis (CP) is a heterogeneous disease defined as chronic inflammatory changes of the pancreatic tissue caused by variety of aetiologies. Oxidative stress accompanying the inflammatory processes has been suggested as an important factor contributing to CP development. The aim of this study was to determine levels of lipid peroxidation products malondialdehyde (MDA) and 4-hydroxynonenal (4-HNE), together with nitrites, the total antioxidant capacity, cytokines, biochemical and haematological parameters in the plasma of patients with CP and control subjects. Levels of MDA and 4-HNE were analyzed using high-performance liquid chromatography. The total antioxidant capacity of plasma against peroxyl radicals was evaluated using chemiluminescence determination. Nitrites were determined using Griess reaction. Cytokines - TNF-alfa; TNF RI; PDGF-AB; TGF-beta, together with myeloperoxidase and hyaluronan were determined using ELISA Kits. Biochemical and haematological parameters were measured by standard methods.

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Marcondes, Daniel Wolinger. "Formação de nitrato e nitrito e degradação protéica por processamento térmico de sardinha (triportheus angulatus)." Universidade Federal do Amazonas, 2010. http://tede.ufam.edu.br/handle/tede/3703.

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Fishing is an important extractive activity in the Amazon, and offering nutritional source income, leisure and food base of a large proportion of its population. His organic constitution, as well as other food matrices, under certain preparation conditions, such as baking, suffers physical and chemical changes, which may give rise to secondary products. The aim of this study was to analyze the formation of nitrates and nitrites (nitrosating compounds), which are important precursors of nitrous compounds from protein myofibrillar degradation caused by application of heat in samples of sardine (Triportheus angulatus) for 30 to 60 minutes. Being a methodology quick, simple and show a sensitive mechanism able to separate the components of the sample, we used the one-dimensional discontinuous SDS-PAGE under the following conditions: 120 minutes, 100 V and 25 mA. With the same samples were quantified the total proteins by the biuret method, determined by the methodology of the MFI measured turbidity and nitrates and nitrites by spectrophotometry. Research suggests that the reaction of nitrosating compounds (nitrates and nitrites) and nitronisáveis (proteins, amino acids and others) originate secondary substances, nitrous compounds. The zymogram revealed degradation of myofibrils in structures with molecular weight between 10 and 20 KDa. Protein content showed a decrease in the amount of protein in the samples roasted for 30 and 60 minutes from about 12.5%, and the determination of MFI was 42.93. The average nitrite in fresh samples, baked 60 minutes and 30 was 0.0001% (m / m), 0.0063% (w / w) and 0.0030% (w / w) respectively. The average nitrate found in fresh samples, baked 30 and 60 was 0.0020% (m / m), 0.00001% (m / m) and 0.00001% (m / m) respectively, both below 0.02% to 0.1% nitrite and nitrate as an upper limit set by law. Their absence or insignificant formation allows us to conclude that there is no relationship between protein degradation as evidenced by the change of myofibrillar zymogram, the MFI and the decrease of total proteins with a possible formation of secondary substances from nitrates and nitrites.
A pesca é uma importante atividade extrativista na Amazônia, sendo fonte nutricional de renda e lazer de grande parte da população. Sua constituição orgânica, assim como de outras matrizes alimentares, sob determinadas condições de preparo sofre alterações físicas e químicas. Pesquisas indicam que reações entre compostos nitrosantes (nitratos e nitritos) e nitronisáveis (proteínas, aminoácidos entre outros) originem substâncias secundárias, como os compostos nitrosos. O objetivo deste trabalho foi quantificar a formação de nitratos e nitritos (compostos nitrosantes), importantes precursores de compostos nitrosos, a partir da degradação protéica miofibrilar por aplicação de calor através de assamento de amostras de sardinha (Triportheus angulatus) durante 30 e 60 minutos com carvão vegetal. Para determinar a perda protéica, foi quantificado o MFI pela metodologia da turbidez. Por apresentar uma capacidade de separação mais eficiente de proteínas e de outros compostos, além de ser uma metodologia de simples execução, relativamente rápida, podendo ser aplicada em varias amostras, também foi utilizado SDS- PAGE descontinua monodimensional para demonstrar perda protéica. O zimograma das miofibrilas evidenciou degradação em estruturas com peso molecular entre 10 e 20 KDa. A dosagem de proteínas mostrou diminuição da quantidade de proteínas nas amostras assadas por 30 e 60 minutos de aproximadamente 12,5%, e a determinação do MFI foi de 42,93. A média de nitritos nas amostras in natura, assadas 30 e 60 minutos foi de 0,0001% (m/m), 0,0063% (m/m) e 0,0030% (m/m) respectivamente. A média de nitratos encontrados nas amostras in natura, assadas 30 e 60 foi de 0,0020% (m/m), 0,00001% (m/m) e 0,00001%(m/m) respectivamente, ambos abaixo dos 0,02% de nitrito e 0,1% de nitrato definidos como limite máximo pela legislação. A sua baixa quantificação tanto in natura, quanto em assado por 30 e 60 minutos permite concluir a existência de uma relação entre a degradação protéica evidenciada pela alteração do zimograma miofibrilar, da quantificação do MFI e das proteínas totais.

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Gamboa, Juan Claudio Mancilla. "Fabricação de sensores eletroquímicos para a determinação de espécies químicas de relevância ambiental." Universidade de São Paulo, 2011. http://www.teses.usp.br/teses/disponiveis/46/46136/tde-18082011-141833/.

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Neste trabalho são apresentados resultados relacionados à determinação de nitrato, nitrito e amônio por técnicas eletroquímicas. Para a determinação de nitrato foi utilizada uma lâmina de cobre cuja superfície é renovada continuamente empregando um processo de ativação (oxidação do cobre e subseqüente redução de íons Cu(II)) com potencial controlado em sistema FIA. As condições ótimas foram alcançadas por meio de 60 s para a etapa de ativação, vazão do transportador 3,0 mL min-1 e volume de amostra 150 µL. A repetibilidade foi estimada em 4,7% (n=9) com freqüência de amostragem de 60 amostras h-1. Trabalhando nas condições otimizadas um aumento na concentração de nitrato gerou um aumento proporcional na corrente, resultando em curva analítica em um intervalo de 0,1 2,5 mmol L-1 (-Ip (µA) = 0,13 + 4,6 [NO3-] (mmol L-1), R2 = 0,9991). Os limites de detecção e quantificação foram estimados em 4,2 (S/N = 3) e 14 (S/N = 10) µmol L-1, respectivamente. O mesmo sensor foi utilizado para determinações de nitrito por voltametria de pulso diferencial e a otimização dos parâmetros relativos ao processo de ativação (tempos de dissolução e redeposição) foi efetuada com o intuito de aumentar a sensibilidade. As condições ótimas foram de 30 s para a etapa de ativação, com uma repetibilidade de 1,9% (n=10), e o aumento nas concentrações de nitrito gerou um aumento proporcional na corrente, resultando em curva analítica em um intervalo de 50 µmol L-1 - 1,44 mmol L-1 (-Ip (µA) = -0,13 + 53,52 [NO2-] (mmol L-1 ), R2 = 0,9996). Os limites de detecção e quantificação foram estimados em 2,8 (S/N = 3) e 9,4 (S/N = 10) µmol L-1, respectivamente. O estudo da morfologia da superfície do eletrodo de cobre durante o processo de ativação foi realizado por AFM com o objetivo de compreender o impacto das mudanças microestruturais no sinal de corrente para nitrato e nitrito. Os resultados indicam que após a ativação do eletrodo a superfície apresenta cristais com uma textura rugosa e ocorre aumento da área superficial, justificando o aumento de sinal de corrente. Para a determinação de amônio foram fabricados eletrodos íon seletivo (ISE) com membrana polimérica de forma tubular, os quais foram acoplados em um sistema de injeção em fluxo. A influência de parâmetros como vazão do transportador e alça de amostragem foi investigada e melhores resultados foram obtidos em 0,5 mL min-1 e 250 µL, respectivamente. Nas condições otimizadas a repetibilidade das determinações foi de 1,3 % (n=10) com freqüência de amostragem de 13 amostras h-1. Tendo em conta as otimizações do sistema FIA, injeções sucessivas de soluções de amônio com concentrações crescentes permitiram obter uma reta com coeficiente angular de 51,2 mV (R2 = 0,9836) no intervalo de 0,2 5 mg L-1. Os limites de detecção foram calculados em 0,05 mg L-1, respectivamente.
This paper presents results related to the determination of nitrate, nitrite and ammonium by electrochemical techniques. A copper electrode whose surface is continuously renewed using an activation process with controlled potential in a FIA system was used for nitrate determinations. The optimum conditions were achieved by an activation step of 60 s, carrier stream of 3.0 mL min-1 and sample volume of 150 µL. The repeatability was estimated as 4.7% (n = 9) with a sampling frequency of 60 samples h-1. At these optimized experimental conditions an increase in nitrate concentration caused a proportional increase in current, resulting in an analytical curve in the range from 0.1 to 2.5 mmol L-1 (-Ip (µA) = 0.13 + 4.6 [NO3-] (mmol L-1), R2 = 0.9991). The limits of detection and quantification were estimated as 4.2 (S/N = 3) and 14 (S/N = 10) µmol L-1, respectively. The same sensor was used for the determination of nitrite by differential pulse voltammetry and the optimization of the parameters involved in the activation process (dissolution and redeposition time) was performed in order to increase the sensitivity. Optimum conditions were established at 30 s for the activation step, with a repeatability of 1.9% (n = 10) and increased concentrations of nitrite generated a proportional increase in current, resulting in an analytical curve in the range from 50 µmol L-1 to 1.44 mmol L-1 (-Ip (µA) = -0.13 + 53.52 [NO2-] (mmol L-1), R2 = 0.9996). The limits of detection and quantification were estimated as 2.8 (S/N = 3) and 9.4 (S/N = 10) µmol L-1, respectively. The study of the morphology of the copper electrode surface upon the activation process was performed by AFM in order to understand the influence of microstructural changes in the current signal for nitrate and nitrite. The results indicated that after the activation the electrode surface presented a rough texture with a concurrent increase in the surface area, justifying the current increase. Ion-selective eletrodes (ISE) with a polymeric membrane in a tubular shape were fabricated for the determination of ammonium in a flow injection system. The influence of parameters such as the carrier stream and the sample volume was investigated and best results were obtained at 0.5 mL min-1 and 250 mL, respectively. Under optimum conditions the repeatability of the determinations was 1.3% (n = 10) with a sampling frequency of 13 samples h-1. Taking into account the optimization of the FIA system, successive injections of solutions with increasing concentrations of ammonium yielded a straight line with slope of 51.2 mV (R2 = 0.9836) in the range 0.2 to 5 mg L-1. The limits of detection were calculated as 0.05 mg L-1, respectively

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Ghosh, Suborno Mukut. "Investigation of the distribution of nitrite and nitrate and nitrite reductase activity in models of cardiovascular disease." Thesis, Queen Mary, University of London, 2014. http://qmro.qmul.ac.uk/xmlui/handle/123456789/8144.

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Recently, it has emerged that the NO metabolites, nitrite and nitrate can be chemically reduced in vivo to biologically active nitric oxide (NO). This generation of NO is dependent on reduction of nitrate to nitrite by facultative anaerobes on the dorsal surface of the tongue, entry of the nitrite into the enterosalivary circuit, transit to the stomach, and absorption through the gut wall into the circulation. Conversion of nitrite to NO is then facilitated by vascular nitrite reductase enzymes. This nitrate-nitrite-NO pathway has been shown to exert a number of beneficial effects in healthy volunteers e.g. lowering of blood pressure, however whether this pathway is affected by cardiovascular disease (CVD) is currently unknown. Ozone chemiluminescence was used to determine and compare nitrite and nitrate levels in 2 models of CVD. To study atherosclerosis wild type (WT) and apolipoprotein E knock out (ApoE KO) mice were used and for hypertension wistar kyoto (WKY) rats as controls vs. spontaneously hypertensive rats (SHR). Assessment of nitrite reductase activity was conducted in the compartment which showed the most consistent differences in distribution, the red blood cell (RBC) and in homogenates of liver tissue. The impact of dietary nitrite and nitrate on distribution of the 2 anions throughout the cardiovascular system was assessed to determine the utility of this approach in restoring levels of these anions in CVD. Finally, using flow cytometry I investigated whether dietary nitrate supplementation could be used to influence inflammatory responses as a mechanism to improve CVD. Compared to WT mice, nitrate levels were reduced in ApoE KO mice in the plasma and across most of the tissues. In contrast in SHRs, reduction of the anions was only apparent in RBCs with no differences compared to WKY in all other tested tissues. Furthermore I have demonstrated that the most efficient way to restore nitrate levels back up to baseline is through a dietary nitrate strategy and that a dose of 15mM nitrate in the drinking water is sufficient to achieve this. In addition I have shown that nitrite reductase activity is enhanced in CVD particularly at the level of the RBC in both atherosclerosis and hypertension and that this enhanced activity is due, in part, to upregulation of xanthine oxidoreductase (XOR). Finally I have shown that dietary nitrate is an effective way to modulate an acute inflammatory response. This modulation is mediated through interfering with the ability of the neutrophil to firmly adhere to the vascular endothelium. These changes were shown to be dose-dependent and concomitant with dose-dependent increases in plasma nitrite and plasma nitrate. These data suggest that utilization of the nitrate-nitrite-NO pathway with dietary nitrate may represent an effective approach for the treatment of CVD.

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Hüsler, Bruno R. "Nitrite/nitrate status in veal calves: effects of feeding nitrite, nitrate, arginine, and iron and of endotoxin administration /." [S.l.] : [s.n.], 1999. http://www.stub.unibe.ch/html/haupt/datenbanken/diss/bestell.html.

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Ferreira, Graziele Cristina. "Alterações induzidas pelo TEMPOL sobre as concentrações de metabólitos do óxido nítrico após o tratamento com nitrito de sódio." Universidade de São Paulo, 2018. http://www.teses.usp.br/teses/disponiveis/17/17133/tde-17042018-142111/.

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No final do século XX o nitrito e nitrato de sódio passaram a ser vistos como possíveis agentes terapêuticos nas doenças cardiovasculares. Estudos iniciais sugeriam que o mecanismo anti-hipertensivo do nitrito de sódio (NaNO2) era pela sua conversão a óxido nítrico (NO) em meio ácido. Estudos posteriores mostraram que a formação de espécies nitros(il)adas também poderiam estar envolvidas nesse mecanismo. Sabemos ainda da importância do ciclo êntero-salivar do NO para a manutenção dos efeitos anti-hipertensivos do nitrito, além do fato que antioxidantes, como o TEMPOL potencializam esses efeitos. Entretanto o mecanismo antihipertensivo exato do NaNO2 e a relevância de cada metabólito do NO (nitrito, nitrato e espécies nitros(il)adas) nesse processo, permanecem obscuros. Este estudo foi realizado a fim de compreender a formação de espécies nitros(il)adas, nitrito e nitrato a partir da administração de NaNO2, e como o TEMPOL pode interferir nessas reações em condições fisiológicas e na hipertensão. Em animais normotensos a administração de NaNO2 aumentou as concentrações de nitrito, espécies nitros(il)adas e nitrato no plasma, coração, fígado e estômago. O TEMPOL potencializou o aumento de nitrito em quase todos os tecidos no intervalo de 15 minutos após a administração de NaNO2. Na hipertensão, as concentrações desses metabólitos ficaram mais baixas comparadas aos animais normotensos, e o TEMPOL não foi mais capaz de potencializar a formação dos mesmos.
At the end of the 20th century, sodium nitrite and nitrate were seen as possible therapeutic agents in cardiovascular diseases. Initial studies suggested that the antihypertensive mechanism of sodium nitrite (NaNO2) was related to its conversion to nitric oxide (NO) in acidic environment. Further studies have shown that formation of nitros(yl)ated species may also be involved in this mechanism. We also know the importance of the enterosalivary circuit of nitrate for the maintenance of antihypertensive effects of nitrite, besides antioxidants such as TEMPOL potentiate these effects. However, the exact antihypertensive mechanism of NaNO2 and the relevance of each NO metabolite (nitrite, nitrate and nitros(yl)ated species) in this process remain obscure. This study was carried out in order to understand a little more about the formation of nitros(yl)ated species, nitrite and nitrate from the administration of NaNO2, and how TEMPOL may interfere in these reactions in physiological conditions and hypertension. In normotensive animals the administration of NaNO2 increased the concentrations of nitrite, nitros(yl)ated species and nitrate in the plasma, heart, liver and stomach. TEMPOL potentiated this increase in almost all tissues within 15 minutes after administration of NaNO2. In hypertension, the concentrations of these metabolites decreased compared to the concentrations found in normotensive animals, and TEMPOL was no longer able to potentiate them. Thus, we concluded that in situations where oxidative stress is lower, we found higher concentrations of NO metabolites after treatment with sodium nitrite.

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17

Jakobs, Kristin. "Hur påverkar dietärt nitrat muskelfunktionen och återhämtningen vid styrketräning? : En pilotstudie i samarbete med Karolinska Institutet och Åstrands laboratoriet." Thesis, Högskolan i Halmstad, Sektionen för ekonomi och teknik (SET), 2011. http://urn.kb.se/resolve?urn=urn:nbn:se:hh:diva-14492.

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Forskning om människans fysiologi och hur den fungerar uppdateras dagligen. Inom idrottens värld testas nya som gamla, naturliga som onaturliga preparat och träningsmetoder kontinuerligt, allt för att optimera en idrottares prestation. Ett ämne som det forskas mycket om idag är kvävemonoxid och dess påverkan i kroppen. Från att ha tolkats som ett skadligt ämne i kroppen har det gått till att möjligen kunna hjälpa hjärtsjuka patienter och även optimera idrottsutövande. Kvävemonoxid bildas i kroppen naturligt med hjälp av syre, men det kan även bildas utan syre genom intag av nitrat som hittas i många grönsaker. Studier om nitrat inom idrottsområdet har koncentrerats till dess påverkan vid uthållighetsidrott och effekten har visat på ökad verkningsgrad och blodflöde till muskulaturen. Senare fann forskarna även hur dietärt nitrat sänkte ens syreupptagningsförmåga (Vo2max) tillsammans med en ökad uthållighet. Detta är en intressant upptäckt då sänkt Vo2max ofta leder till en försämrad arbetsprestation. Dessa studier ger en bild av hur nitrat fungerar vid aerobt arbete, det vill säga med syre. Det som forskningen inte tagit upp ännu är hur nitrat påverkar anaerobt arbete och maximala prestationer som förekommer vid styrketräning. Syftet med denna studie var därför att undersöka hur nitrat påverkar muskelfunktion och uthållighet vid styrketräning. I en randomiserad, dubbelblind, korsande studie, konsumerade åtta män (ålder 19-26, 23 (±2, 3)) nitrat eller placebo (0,1 mmol/kg kroppsvikt/dag) under tre dagar. Under fjärde dagen testades männens prestation i fyra olika styrketest. Laktat och glukosvärden mättes för att se hur den laktacida systemet påverkades. Studien gav inget stöd till att dietärt nitrat påverkar styrketräning. Resultaten från tillfället med nitrat respektive placebo förblev i stort sett oförändrade. Slutsatsen blev att ett intag av nitrat inte har någon större betydelse för denna modell av styrketräning. Den främsta förklaringen till detta kan tänkas vara att nitratet ger störst inverkan vid långvariga arbetsdurationer och främst under aerobt arbete. I detta fall används mestadels lagrad energi i kroppen, och energisystemen där syre krävdes är troligen inte av större betydelse.
Research on human physiology and how it is working is updated daily. In the world of sports they are testing new as old, natural as unnatural preparations and different training methods continuously in order to optimize athletic performance. A substance that´s been research on, up till today is nitric oxide and its influence in the body. From being interpreted as a harmful substance in the body, it went to possibly help heart disease patients, and also optimize the physic in sport performance. Nitric oxide is formed in the body naturally by oxygen, but it can also be formed without oxygen through the ingestion of nitrates found in many vegetables. Studies on nitrate in the sport field have concentrated on the effect on endurance sports and the effect has been shown to increase the efficiency and the blood flow to the muscles. Later on they also found that nitrate supplementation seems to give a lower Vo2max together with an increased time to exhaustion. These findings are really interesting because normally a reduction in Vo2max leads us to a decrease in workability. All these studies give an idea on how nitrate works aerobic, that is with oxygen. The research has not yet an explanation on how nitrate affect anaerobic work and maximum performance that occurs in weight training. The purpose of this study was to investigate how nitrate affects muscle function and endurance in strength training. In a randomized, double-blind, crossover trial, eight men (age 19-26, 23 (±2, 3)) consumed nitrate or a placebo (0.1 mmol/kg bodyweight/day) for three days. During the fourth day the test persons were tested in four different strength tests to see how they performed. Lactate and glucose concentrations were measured to see how the laktacid system was influenced. The study gave no support that dietary nitrate affects weight training. The results from the occasion with nitrate respectively placebo remained essentially unchanged. It was concluded that an intake of nitrate not will give any significant effects on the model of strength training. The main reason for this may be that nitrate provides the greatest impact on long-term work-duration and mainly during aerobic work. In this case the main use is mostly stored energy in the body, and the energy systems in which oxygen is required will probably not be of major importance.
Pilotstudie i samarbete med Åstrands laboratoriet och Karolinska Institutet

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18

Liu, Donald. "Ultraviolet A irradiation on human skin : nitric oxide mediated cardiovascular responses." Thesis, University of Edinburgh, 2012. http://hdl.handle.net/1842/8179.

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Cardiovascular disease (CVD) such as hypertension and stroke are serious illnesses that impact on the lives of millions all over the world, with 972 million (26% of the world’s population) suffering from hypertension in year 2000, and an estimated 1.56 billion to be affected by 2025. Hypertension, being one of the most common CVD is associated with the development of stroke, peripheral vascular diseases, myocardial infarction, renal failure as well as cardiac failure. Several studies have shown a seasonal correlation for both the systolic and diastolic blood pressure in mankind. A hypertension trial done by the Medical Research Council in the 1980s showed the average blood pressure being lower in summer than winter, and this difference was more significant in the elderly than the younger population. Other than seasonal variation, blood pressure (including hypertension prevalence) is also noted to correlate with latitude, being higher at places further away from the equator. Other cardiovascular related diseases such as stroke and acute coronary syndrome are also shown occur more frequently in winter. The morbidity and mortality of CVD could be due to various factors including diet, culture, race and social status, but within the United Kingdom, all cause mortality (with cerebral-vascular disease being the major one) correlates with latitude even after accounting for all known risk factors, with CVD risks highest in the north. We propose that this difference in cardiovascular mortality is caused by variations in ultraviolet exposure other than temperature. Known mechanisms of sunlight exposure that affect cardiovascular health include temperature and the ultraviolet B (UVB) mediated photolysis of 7-dehydrocholesterol in the skin to produce 1,25 dihydroxycholecalciferol (Vitamin D). UVB is however a potent skin carcinogen, and calculating risk-benefit ratios for exposure will be important. We believe that independently of vitamin D, nitric oxide plays an important role in blood pressure regulation and cardiovascular health, accounting for seasonal and latitude variation. In 1961, Furchgott demonstrated relaxation of rabbit aorta by irradiating them with ultraviolet light, and in later research he noted this effect is most significant in the ultraviolet A (UVA) spectrum. Recently, Mowbray showed a rich store of various nitro-species within human skin and Oplander showed a reduction of blood pressure in human after giving whole body UVA irradiation. We therefore hypothesize that independently of vitamin D, NO mediates the UVA induced beneficial effects on cardiovascular health. To support our hypothesis, in vivo as well as in vitro studies were conducted. We recruited a total of 63 healthy volunteers and monitored blood pressure, forearm blood flow as well as other cardiovascular parameters before and after UVA irradiation. Blood samples were also taken for the measurement of circulatory nitro-species. We have noted a significant reduction of blood pressure (from 84.5±1.76 to 81.33±1.37 mmHg) and increased forearm blood flow (1.95±0.28 to 2.94±0.47 mL/100mL of tissue/min) after UVA irradiation of human skin; simultaneously, we also noted a rise in circulatory nitrite (0.5±0.04 μM before irradiation to 0.72±0.04 μM) and a drop in circulatory nitrate (11.79±0.64 μM before irradiation and 8.99±0.4 μM). For us to further clarify the role of nitric oxide in different latitude, a monochromator machine that generates specific wavelength of light was been used to irradiate aqueous nitrite solution, and the total amount of nitric oxide release at different latitude was then calculated according to the irradiance of various wavelength across the globe. The results of our studies provide evidence suggesting that nitric oxide release induced by UVA irradiation of the skin can account for the difference in cardiovascular mortality and morbidity by latitude. The current public health advice of avoiding sun exposure to reduce the risk of developing skin cancer may need to be modified.

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Modolo, Luzia Valentina. "Produção de oxido nitrico pela oxido nitrico sintase, nitrato redutase e uma atividade mitocondrial redutora de nitrito na resposta de defesa de Arabidopsis thaliana a Pseudomonas syringae." [s.n.], 2004. http://repositorio.unicamp.br/jspui/handle/REPOSIP/314345.

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Orientador: Ione Salgado
Tese (doutorado) - Universidade Estadual de Campinas, Instituto de Biologia
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Resumo: A origem do óxido nítrico (?NO) em plantas tem sido controversa e uma enzima do tipo óxido nítrico sintase (NOS), bem como nitrato redutase (NR) são consideradas possíveis fontes deste radical livre. Contudo, ainda não há nenhuma evidência direta da formação de ?NO a partir da NR durante interações planta-patógeno. Nos estudos aqui descritos foram utilizadas plantas de Arabidopsis thaliana deficientes na enzima NR para investigar o mecanismo de produção de ?NO em resposta à inoculação da bactéria Pseudomonas syringae pv. maculicola (Psm). Aumento na síntese de L-citrulina a partir de L-arginina foi observado em homogenatos de folhas de plantas do tipo selvagem e daquelas deficientes na síntese de NR, após inoculação com Psm. Experimentos de ressonância paramagnética eletrônica, contudo, mostraram uma produção muito maior de ?NO dependente de NO2-, mas não de L-arginina ou NO3-, síntese esta inibida por alta concentração de L-arginina. A inibição da cadeia de transporte de elétrons da mitocôndria aboliu ou inibiu parcialmente esta atividade em plantas mutantes ou selvagens, respectivamente. A utilização do marcador fluorescente 4,5 diaminofluoresceína diacetato (DAF-2DA) mostrou que a inoculação com Psm aumentou substancialmente a produção de ?NO in situ em plantas selvagens, mas não em mutantes deficientes na síntese de NR. No entanto, a infiltração de L-arginina ou NO2- causou uma produção de ?NO in vivo nas plantas mutantes. Plantas de A. thaliana deficientes na síntese de NR mostraram suscetibilidade à P. syringae que foi prevenida pela co-infiltração de NO2-. O conjunto de resultados sugere que NOS, NR e uma importante atividade mitocondrial de redução de NO2- podem cooperar para produzir ?NO em quantidade suficiente para prevenir a disseminação de Psm em plantas de A. thaliana
Abstract: The origin of nitric oxide (?NO) in plants has been controversial and nitric oxide synthase (NOS)-like enzyme and nitrate reductase (NR) are claimed as potential sources. However, there is still no direct evidence for ?NO formation from NR during plant-pathogen interactions. Here, we used NR-defective double mutants of Arabidopsis thaliana to investigate the mechanism of ?NO production following infection by an avirulent strain of Pseudomonas syringae pv. maculicola (Psm). Increased formation of L-citrulline from L-arginine was observed in leaf homogenates of both wild-type and nia1 nia2 mutant plants. Electron paramagnetic resonance experiments, however, showed a much higher ?NO production that was dependent on NO2- rather than on L-arginine or NO3- and was also inhibited at high L-arginine concentrations. Inhibition of mitochondrial electron transport abolished and inhibited partially this activity in nia1 nia2 mutants and wild-types, respectively. In situ ?NO production was substantially increased in wild type-plants but not in mutants, following Psm challenge, as measured with the fluorescent probe 4,5-diaminofluorescein diacetate. However, in vivo ·NO production in NR-deficient mutants was visualized only after L-arginine or NO2- infiltration into the leaves. A. thaliana plants defective in NR showed susceptibility to P. syringae that was prevented by infiltration of NO2-. The overall results suggest that NOS, NR, and an important mitochondrial-dependent nitrite-reducing activity cooperate to produce ?NO in amounts enough to prevent Psm dissemination in A. thaliana plants
Doutorado
Bioquimica
Doutor em Biologia Funcional e Molecular

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Agell, Blenda. "Effect of Antibacterial Mouthwash on Basal Metabolic Rate in Humans : A Randomized, Double-blinded, Cross-over Study." Thesis, Linnéuniversitetet, Institutionen för kemi och biomedicin (KOB), 2013. http://urn.kb.se/resolve?urn=urn:nbn:se:lnu:diva-30774.

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The use of mouthwash is a common complement to oral care. However, the physiological implication of this use, besides of effects on oral hygiene, is poorly known. The research of the gut micro flora and its implications on the host is a very active area of research today. Many important connections between the gut micro flora and obesity and diabetes have been found. These billions of bacteria are part of the immune system, they produce essential vitamins and they make inaccessible polysaccharides more digestible to the host, just to mention a few of their symbiotic roles for the host. A less explored area is the micro flora in the oral cavity. On the back of the tongue, anaerobic bacteria can reduce dietary nitrate to nitrite which then further can be reduced to nitric oxide, NO. NO is important in several important biological functions, e.g. as a signal substance, vasoregulation, mucus production and antibacterial effects. Vegetables as beetroot and spinach are dietary sources with a high nitrate content. Also drinking water and processed meats can be of relevance. Nitrite is added to processed meat for the prevention of botulism but also adds taste and color. Experiments on humans indicate that mitochondrial efficiency increases after nitrate load, manifested as a decreased oxygen demand during physical exercise. This can also be relevant under conditions where the mitochondrial function is impaired, such as in diabetes and cardiovascular diseases. First a pilot study was made to evaluate the nitrate reducing effect from the antibacterial mouthwash. The mouthwash proved very effective. The concentrations of nitrate and nitrite in saliva was analyzed by HPLC and saliva from the antibacterial treatment showed greatly reduced concentrations of nitrite and high concentrations of nitrate. Saliva from placebo mouthwash showed high concentrations of nitrite and low concentrations of nitrate as expected. To study the importance of oral bacteria on metabolism, we performed a randomized, cross-over double-blinded study with 19 healthy males between 22-43 years. During two separate three-day periods they used an antibacterial and placebo mouthwash, respectively. On the fourth day their basal metabolic rate (BMR) was measured with an indirect calorimetric system. Moreover, samples from saliva, urine and blood were collected but these results are not included in this thesis. An earlier, unpublished study has demonstrated that nitrate administration reduces the basal metabolic rate. Accordingly, our aim was to study potential effects on the basal metabolic rate following reduction of the number of oral bacteria by aid of antibacterial mouthwash. Our hypothesis was that the reduced availability of nitrite would decrease the availability of NO in the body and manifest as an increased basal metabolic rate. The results from indirect calorimetry measurements showed no significant difference between placebo and antibacterial mouthwash, but there may be confounding factors. Further study is needed to assess the potential effects on host metabolism by these bacteria.

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Liu, Jia Clinical School Prince of Wales Hospital Faculty of Medicine UNSW. "Nitric oxide in airway inflammation." Publisher:University of New South Wales. Clinical School - Prince of Wales Hospital, 2009. http://handle.unsw.edu.au/1959.4/43678.

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Exhaled breath condensate (EBC) is a non-invasive method of investigating airway inflammation associated with nitric oxide (NO) and the metabolites nitrite/nitrates (NOx) in diseases such as chronic obstructive pulmonary disease (COPD), but some of the variables affecting the results are unknown. It was hypothesised that 1) EBC would be influenced by lung volumes and the type of EBC collection device; 2) fractional exhaled NO (FENO) and EBC NOx in COPD patients would be altered by smoking and glucocorticosteroids (GCS); 3) cigarette smoke could contribute to the EBC NOx concentration while it may also decrease FENO indirectly by converting airway NO to NOx. It was found that EBC volume was significantly correlated with both tidal volume and minute volume. Comparing four EBC collection devices demonstrated greater efficiency with the ECoScreen?? than siliconised glass tubes or RTube?? but it gave factitiously high NOx levels. Total EBC protein levels over a 10-minute collection were significantly higher using the ECoScreen?? than either glass or RTube?? devices. A cross-sectional study of 96 COPD patients and 80 age-matched control subjects demonstrated that FENO levels in COPD patients were significantly higher than normal subjects when comparing either the combined groups or appropriate two subgroups: ex-smokers and smokers. GCS treatment demonstrated no significant effect on either FENO levels or EBC NOx, but EBC NOx was elevated in smokers. In vitro, cigarette smoke extract (CSE) induced significantly higher NOx and asymmetric dimethylarginine (ADMA) levels in A549 cells when compared with control media. The anti-oxidant, NAC pre-treatment partially reversed the elevated NOx levels but not the ADMA levels. This thesis is the first to report FENO and EBC NOx in COPD patients in an appropriate sample size to be able to evaluate each subgroup, and the increased EBC NOx levels found in smokers in vivo was consistent with the elevated NOx level in response to CSE observed in vitro. These data indicate that smoking-related airway inflammation and activation of the NO pathway are complex with both an increase in ADMA, NO, NOx and may be regulated by oxidative stress rather than the nitric oxide synthase (NOS) pathway.

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Silva, Jordanna de Almeida e. "Intoxicação experimental por nitrato/nitrito em bovinos suplementados com nitrato de cálcio encapsulado." Universidade Federal de Goiás, 2014. http://repositorio.bc.ufg.br/tede/handle/tede/4295.

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The objective of this research was to identify clinical and laboratory findings caused by the ingestion of calcium nitrate, encapsulated or conventional in different doses in cattle. Were used five bovines, cannulated, Nelore breed, male, with an average body weight of 500 kg were maintained during the entire experimental period in individual stalls with individual troughs for food and water. The experiment consisted of 75 days divided into five periods of 15 days. In each period the first 13 days were used for adaptation of the diet (Phase 1) followed by two days of collections (Phase 2). The experimental design was a latin square and the experimental groups were divided in the following way: not containing added nitrate in the diet (G1). 1.82% calcium nitrate and ammonium decahydrate without encapsulation in dry diet supplying 15% nitrogen (G2), 3.64% calcium nitrate and ammonium decahydrate without encapsulation in dry diet supplying 30% of nitrogen (G3), 2.58% calcium nitrate and ammonium decahydrate with encapsulation in dry diet providing 15% nitrogen (G4), 5.16% calcium nitrate and ammonium decahydrate with encapsulation in the dietary dry matter providing 30% nitrogen (G5). Data were analyzed using the R software (The R Development Core Team, 2010) in which was used the Tukey test by adopting a significance level of 5%. The animals were placed in contention tie stalls to perform physical examination. Then, were obtained blood samples for hemogram, fibrinogen, plasma protein, methemoglobin, nitrate and nitrite, blood biochemical, and ruminal fluid to measure pH, count protozoa and quantification of nitrite and nitrate. Changes in the hematological and biochemical examinations were nonspecific and punctual, while the methemoglobinemia was detected all livestock. The G3 group showed severe clinical signs requiring therapeutic intervention with methylene blue, which has been providing effective reductions in the levels of nitrate, nitrite and methemoglobin. Bovines to G2 and G4 groups have had similar clinical and laboratory results, not justifying the processing of nitrate font. The dose related to the G5 was efficient in preventing toxicosis nitrate / nitrite, however new research should be carried out to prove its cost / benefit.
O objetivo da presente pesquisa foi identificar alterações clínicas e laboratoriais ocasionadas pela ingestão de diferentes doses de nitrato de cálcio encapsulado ou convencional em diferentes doses em bovinos. Foram utilizados cinco bovinos fistulados, da raça Nelore, machos, com peso vivo médio de 500 kg, mantidos durante todo o período experimental em baias individuais com cochos individuais de água e comida. O experimento consistiu de 75 dias dividido em cinco períodos de 15 dias. Em cada período os primeiros 13 dias foram utilizados para adaptação da dieta (Fase 1) seguidos de dois dias de coletas (Fase 2). O delineamento experimental utilizado foi o quadrado latino e os grupos experimentais foram divididos da seguinte forma: sem adição de nitrato na dieta (G1); 1,82% de nitrato de cálcio e amônio decahidratado sem encapsulamento na matéria seca da dieta fornecendo 15% de nitrogênio (G2); 3,64% de nitrato de cálcio e amônio decahidratado sem encapsulamento na matéria seca da dieta fornecendo 30% de nitrogênio (G3); 2,58% de nitrato de cálcio e amônio decahidratado com encapsulamento na matéria seca da dieta fornecendo 15% de nitrogênio (G4); 5,16% de nitrato de cálcio e amônio decahidratado com encapsulamento na matéria seca da dieta fornecendo 30% de nitrogênio (G5). Os dados foram analisados pelo software R (The R Development Core Team, 2010) em que utilizou o teste Tukey adotando-se grau de significância de 5%. Os animais foram colocados em tronco de contenção para a realização de exame físico. Em seguida, foram obtidas amostras de sangue para a realização de hemograma, fibrinogênio, proteína plasmática, metemoglobina, nitrato e nitrito, bioquímicas sanguíneas, além de fluido ruminal para aferir ph, contagem de protozoários e quantificação do nitrito e nitrato. As alterações nos exames hematológicos e bioquímicos foram inespecíficas e pontuais, enquanto que a metemoglobinemia foi detectada em todos os animais. O grupo G3 apresentou sinais clínicos severos necessitando intervenção terapêutica com azul de metileno, que foi eficaz proporcionando reduções nos níveis de nitrato, nitrito e metemoglobina. Os bovinos dos grupos G2 e G4 tiveram resultados clínicos e laboratoriais semelhantes, não justificando o processamento da fonte de nitrato. A dose referente ao G5 foi eficiente na prevenção da toxicose de nitrato/nitrito, porem novas pesquisas devem ser realizadas para comprovar seu custo/benefício.

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23

Melane, Pumeza. "Kinetics reactions of Ammonium Nitrate-Sodium Nitrite Reaction and Ammonium Nitrate Emulsion Explosives." Master's thesis, University of Cape Town, 2010. http://hdl.handle.net/11427/6333.

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The aim of this study was to understand and control the gasification rates in ammonium nitrate emulsion explosive using ammonium nitrate-sodium nitrite reaction. This reaction produces N2 gas which is the sensitizer in emulsion explosives. The NH4NO3-NaNO2 gassing reaction produces N2 gas and so the reaction could be followed by the pressure increase in a closed reaction vessel. The reaction is pH sensitive, so the role of pH was investigated in the pH range 2 to 5. Gasification reactions for unbuffered NH4NO3-NaNO2 reaction were found to be rapid below pH = 3 and maximum pressure was attained within 2 hours of starting the reaction. At pH = 4.5 and 5 the reaction failed to attain maximum pressure. Initial rate of reaction showed sensitivity to pH, the rate of reaction decreasing with increasing pH. The reaction was found to be second order with respect to nitrite species. The effects of three different buffers (potassium hydrogen phthalate, sodium formate and sodium citrate) were also investigated. At pH = 3 pressure traces for the buffered reactions had attained maximum pressure while at pH = 3.5 only sodium citrate buffer had reached a pressure stable state. The presence of the buffers resulted in a lower overall pressure change and absolute pH change and higher rate constants and initial rate of reaction than in their absence. iv A Lewis acid (Zinc Nitrate) was added to the buffered and unbuffered NH4NO3-NaNO2 reactions to investigate a patent claim that addition of a Lewis acid would increase the rate of reaction. The presence of zinc nitrate in the buffered reactions resulted in rapid pressure increase; higher initial rate of reactions than the unbuffered with zinc nitrate. Ammonium nitrate solution was emulsified resulting in an ammonium nitrate emulsion explosive and kinetics of gasification was investigated. The gasification reactions were found to be rapid at pH 3.2, slowing significantly with increased pH as indicated by initial rates of reaction and as predicted by the gasification reaction rate law. Maximum pressure increase was attained within three hours at pH 3.2, whereas reactions conducted at pH 4.0 and 4.5 failed to reach maximum pressure even after 24 hours as evidenced by plots of pressure versus time. The effect of buffers in the ammonium nitrate emulsions was also investigated.

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24

Pereira, Amanda de Carvalho. "Mecanismos celulares envolvidos no relaxamento da aorta de ratos induzidos pelo composto doador de óxido nítrico cis-[Ru(bpy)2(py)(NO2)](PF6)(RuBPY)." Universidade de São Paulo, 2011. http://www.teses.usp.br/teses/disponiveis/60/60138/tde-19092011-153025/.

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O óxido nítrico (NO) é o principal agente vasodilatador endógeno que regula o tônus e a homeostase vascular. Dentre os compostos doadores de NO, estão os complexos nitrosilos de rutênio. No presente estudo, o doador de NO estudado, RuBPY, não apresenta citotoxicidade para células do músculo liso vascular (MLV) ao contrário do NPS. O RuBPY apresenta eficácia semelhante ao NPS em relaxar o MLV de aorta de ratos, porém o NPS é mais potente. Ambos compostos liberam NO do tipo radicalar (NO) no meio intracelular, mas o NPS libera também íon nitroxil (NO-). O sequestrador da espécie NO (hidroxocobalamina) reduziu mais a resposta relaxante estimulada com RuBPY do que com o NPS. Nenhum dos dois compostos precisa ser reduzido quimicamente para liberar NO, uma vez que houve relaxamento quando utilizamos alta concentração de KCl como agente contrátil. Porém, este relaxamento foi inibido, o que mostra a importância dos canais para K+ no relaxamento induzido pelos doadores de NO. O bloqueador não seletivo de canais para K+ (TEA), inibiu somente o relaxamento ao RuBPY. A via NO-GCs-GK é ativada por ambos doadores de NO, para induzir relaxamento. A inibição da degradação do GMPc potencializou o relaxamento estimulado com RuBPY e NPS. O armazenamento de Ca+2 no retículo sarcoplasmático (RS) via ativação da SERCA é importante somente para o relaxamento induzido com RuBPY. O composto RuBPY inibiu a resposta contrátil estimulada com fenilefrina devido ao armazenamento de Ca+2 no RS e também por inibir o influxo capacitivo de Ca+2. A presença do endotélio vascular não alterou o relaxamento induzido pelo RuBPY, porém potencializou o relaxamento induzido pelo NPS. A análise da liberação de NO por amperometria demonstrou que o RuBPY libera NO somente em presença do tecido aórtico de ratos. Portanto, não houve liberação espontânea de NO, por fotólise pela luz visível ou por redução química. É necessária a presença de heme-proteínas como a guanilil-ciclase solúvel (GCs) inibida pelo ODQ, para haver a conversão do nitrito presente no RuBPY, a NO. Pela quantificação da fluorescência emitida pela sonda DAF-2DA, RuBPY liberou cerca de 3,5 vezes mais NO do que o NPS. Pela medida do potencial de membrana, demonstramos que o RuBPY induz hiperpolarização de membrana de células isoladas do MLV da aorta de rato. RuBPY tem efeito hipotensor dose-dependente, em ratos hipertensos renais, o que não ocorre em animais normotensos. A redução da pressão arterial em ratos hipertensos é maior do que nos normotensos. Em estudos iniciais de farmacocinética, verificamos que o composto RuBPY é absorvido por via oral e é distribuído entre alguns tecidos após ser administrado aos ratos, por gavagem.
Nitric oxide (NO) is the main endogenous vasodilator agent that regulates vascular tone. Among the compounds which are able of releasing NO, are the nitrosyl ruthenium complexes. The NO donor studied, RuBPY, does not present cytotoxicity in smooth muscle cells (SMC), in contrast to SNP. RuBPY has similar efficacy to SNP in inducing rat aorta relaxation, although SNP is more potent. Both compounds release intracellular radicalar NO (NO), and SNP also release ion nitroxyl (NO-). The NO scavenger (hydroxocobalamine) had greater effect on the relaxation induced by RuBPY than by SNP. Both compounds do not need to be chemically reduced to release NO, as demonstrated in aorta relaxation after pre-contraction with high concentrations of KCl. However, this relaxation was impaired, showing the importance of K+ channels to induce relaxation by NO released from these compounds. By using non-selective blocker for K+ channels (TEA), only the relaxation induced by RuBPY was inhibited. The NO-sGC-GK pathway is activated by NO donors to induce relaxation. Inhibition of cGMP degradation, potentiated the effect of RuBPY and SNP. Storage of Ca+2 in the sarcoplasmic reticulum (SR) via activation of SERCA is important only for the relaxation induced by RuBPY. The contractile response induced by phenylephrine was inhibited by RuBPY due to the storage of Ca+2 in RS and also by inhibiting the capacitive influx of Ca+2. The presence of endothelium had no effect on the relaxation induced by RuBPY, but it potentiated the relaxation induced by SNP. RuBPY released NO only in the presence of the rat aorta. The complex RuBPY did not spontaneously release NO, by photolysis by visible light, or by chemical reduction. RuBPY requires the presence of heme-protein such as guanylyl-cyclase, inhibited by ODQ, to convert nitrite to NO. The amount of NO released from RuBPY was about 3.5 times greater than that released from SNP. RuBPY induced membrane hyperpolarization of SMC. RuBPY has hypotensive effect in renal hypertensive rats in a dose-dependent way, which does not occur in normotensive rats. The decreased of blood pressure in hypertensive rats was greater than in normotensive rats. Initial studies of pharmacokinetics demonstrated that RuBPY is orally absorbed and it is also distributed in some tissues after being administered by gavage to rats.

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25

Baseler, Laura Jean. "A comparison of residual nitrite and nitrate, lipid oxidation, cut-surface color, and sensory and visual characteristics for nitrite-added and no-nitrite- or -nitrate-added Canadian-style bacon." [Ames, Iowa : Iowa State University], 2009. http://gateway.proquest.com/openurl?url_ver=Z39.88-2004&rft_val_fmt=info:ofi/fmt:kev:mtx:dissertation&res_dat=xri:pqdiss&rft_dat=xri:pqdiss:1473178.

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26

Dhakal, Prakash. "ABIOTIC NITRATE AND NITRITE REACTIVITY WITH IRON OXIDE MINERALS." UKnowledge, 2013. http://uknowledge.uky.edu/pss_etds/30.

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Under iron (Fe3+)-reducing conditions where aqueous Fe2+ and unreduced solid Fe3+-oxides commonly coexist, soil Fe2+ oxidation has been shown to be coupled with nitrate (NO3-) reduction. One possible secondary reaction is the involvement of NO3- and nitrite (NO2-) with Fe-oxide minerals found in many natural environments. Yet, spectroscopic measurements and kinetic data on reactivity of NO3- and NO2- with Fe-containing oxide minerals such as goethite (a-FeOOH), and magnetite (Fe3O4) are not found in the literature. The reactivity of goethite and magnetite with NO3- and NO2- was studied over a range of environmentally relevant pH conditions (5.5-7.5) with and without added Fe2+(aq) under anoxic conditions. Laboratory experiments were conducted using stirred batch experiments and reaction products were analyzed using ion chromatography (IC), gas chromatography (GC), ultraviolet visible near infrared spectroscopy (UV-VIS-NIR), x-ray diffraction (XRD), scanning electron microscopy (SEM), Mössbauer, and Attenuated total reflection-Fourier transform infrared (ATR-FTIR) spectroscopy. Nitrate removal by goethite and magnetite was much slower when compared with NO2-. There was a pH-dependence in the reduction of NO2-, and the initial rate of NO2- removal was nearly 2 and 8 times faster at pH 5.5 than at pH 7.5 by magnetite and goethite, respectively. Nitric oxide (NO) and nitrous oxide (N2O) were identified as products when NO2- has reacted with magnetite, whereas N2O is the major reaction product in the experiment with goethite. In comparison to experiments containing magnetite or goethite alone, addition of Fe2+ greatly accelerated the NO2- removal rate. Wet chemical experiments combined with the Mössbauer study reveals that NO2- reduction to NO and subsequently to N2O by magnetite occurs via a heterogeneous electron transfer process. ATR-FTIR and diffuse reflectance spectroscopy (DRS) results from the studies with goethite indicate that NO2- was removed from solution by adsorption in a surface complex involving the oxygen atoms, and a portion of the nitrite is reduced to NO and N2O. This study suggests that under anaerobic conditions soil and sediments that contain goethite, magnetite, and other Fe3+-oxides can catalyze abiotic NO2- reduction and the kinetics data from this study can be used to predict the NO2- removal under such conditions.

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27

Toyohara, Doroti Quiomi Kanashiro. "Determinação de nitrato, nitrito e N-Nitrosaminas em linguiças." [s.n.], 1989. http://repositorio.unicamp.br/jspui/handle/REPOSIP/256291.

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Orientador : Felix Guillermo Reyes Reyes
Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia de Alimentos
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Resumo: O presente trabalho teve por objetivo determinar em vários tipos de lingüiças comerciais de diferentes procedências, o teor residual de nitrato e de nitrito, assim como identificar e quantificar o conteúdo de N-nitrosaminas voláteis. Para fins de comparação com as amostras de lingüiças comerciais foram processadas na Faculdade Engenharia de Alimentos, Universidade Estadual Campinas (FEA/UNICAMP), lingüiças do tipo frescal e cozida com a adição de 200 mg/kg nitrito de sódio (NaNO2), na presença ou não de 500 mg/kg de ascorbato de sódio. Nestas amostras foi realizada a dosagem de nitrato e de nitrito durante as etapas de processamento e estocagem, assim como a identificação e quantificação das N-nitrosaminas voláteis. Com o propósito de verificar a eficácia do nitrito foi realizada uma avaliação microbiológica (mesófilos e psicrófilos), tendo sido também realizada uma avaliação sensorial de cor e de preferência nas amostras. A determinação do nitrato e nitrito nas lingüiças comerciais de origem conhecida e de fabricantes não identificados indicaram 3% e 31% das amostras, respectivamente, apresentaram teores residuais da soma de nitrato e nitrito acima do limite estabelecido pela legislação em vigor. Para as lingüiças processadas na FEA/UNICAMP, durante as etapas de processamento e estocagem, verificou-se uma perda do teor residual de nitrito da ordem de 13% e 73% para lingüiça frescal e cozida, respectivamente, sendo a mesma maior na presença de ascorbato de sódio. Não foi verificada variação aparente no teor de nitrato residual. Em relação à contagem total de mesófilos e psicrófilos, as amostras apresentaram e conservação satisfatória por um período de até 12 e 30 dias de armazenamento (4 ± 2°C), respectivamente, para as lingüiças do tipo frescal e cozida. Os resultados da avaliação sensorial realizados após 7 e 19 dias de estocagem, indicaram que lingüiças contendo nitrito e nitrito mais ascorbato apresentaram diferença significativa (ao nível de 1%) da amostra controle, tendo sido verificada maior média para aquelas amostras contendo nitrito mais ascorbato. A identificação e quantificação das N-nitrosaminas foram realizadas, na "Oregon State University, Oregon, USA", por cromatografia gasosa acoplada ao detector TEA ("Thermal Energy Analyzer"). A confirmação destas substâncias foi feita por espectrometria de massa (MS). Os resultados indicaram que todas as amostras de lingüiça comercial estudadas apresentaram quantidades detectáveis de N-nitrosodimetilamina (NDMA) e de N-nitrosopirrolidina (NPIR), assim como a maioria dessas amostras também apresentou N-nitrosomorfolina (NMORF). Os níveis encontrados de NDMA (97,5 ± 59,1 µg/kg) e de NPIR (43,1 ± 37,9 µg/kg) foram, aproximadamente, 10 vezes maiores do que aqueles relatados recentemente na literatura. O conteúdo de NMORF encontrado foi de 8,5 ± 7,4 µg/kg. Em contrapartida, das amostras processadas na FEA/UNICAMP, somente duas apresentaram quantidades detectáveis de NDMA (1,1 e 3,0 µg/kg) e uma de NPIR (6,2 µg/kg), níveis estes comparáveis com aqueles relatados na literatura recente
Abstract: The objective of the present work was to determine in various types of commercial sausages from various sources the residual contents of nitrites and nitrates and to identify and quantify the volatile N-nitrosamines. For comparision with commercial sausages samples of fresh and cooked sausages were processed in the Faculdade de Engenharia de Alimentos, Universidade Estadual de Campinas (FEA/UNICAMP) with the addition of 200 mg/kg sodium nitrite (NaNO2) in the presence or not of sodium ascorbate (500 mg/kg). In these samples, the determination of nitrate and nitrite was performed during the processing and storage and the identification and quantification of volatile N-nitrosamines were determined during storage. To verify the efficiency of nitrite as preserving agent, microbiological analyses (mesophylus and psycrophylus) were performed. Determination of nitrite and nitrate in commercial sausages indicate that 3% of the samples where the processors were identified and 31% of the samples from unidentified processor has residual amounts where the sum of nitrite and nitrate was above the stablished limits. During processing and storage (4 ± 2ºC), sausages prepared in FEA/UNICAMP, showed a loss of residual nitrite of approximately 13% and 73% in fresh and cooked sausages, respectively. This loss was higher in the presence of sodium ascorbate. No apparent change in residual nitrate content was observed. In relation to the total count of mosophylus and psycrophylus, the sample showed satisfactory preservation for a period up to 12 and 30 days for fresh and cooked sausages, respectively. Results of sensorial evaluation performed after 7 and 19 days of storage, indicated that the sausages containing nitrite and nitrite plus ascorbate showed a significant difference (P<0.01) from the control sample. Samples containing nitrite plus ascorbate had higher average scores for colour and preference than those not containing ascorbate. The identification and quantification of N-nitrosamines were performed, at the Oregon State University, Oregon, USA, by gas chromatography coupled to a TEA detector ( Thermal Energy Analyzer detector). The confirmation of these substances was performed by mass spectrometry (MS). The results indicated that all the commercial sausage studied presented detectable quantities of N-nitrosodimethylamine (NDMA) and N-nitrosopyrrolidine (NPYR). In addition, most of the samples also showed N-nitrosomorpholine (NMOR) The levels of NDMA (97.5 ± 59.1 µg/kg) and NPYR (43,1 ± 37.9 µg/kg) found were approximately 10 times higher than those recently reported in the literature. The content of NMOR was 8.5 ± 7.4 µg/kg. On the other hand, of the 8 samples processed in FEA/UNICAMP only 2 of them presented detectable quantities of NDMA (1.1 and 3.0 µg/kg) and one of NPYR (6.2 µg/kg). These levels are comparable with those recently reported in the literature
Mestrado
Mestre em Ciência de Alimentos

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Butala, Nitin Santosh. "Nitrate- and Nitrite-Reductase Activities in Mycobacterium Avium A5." Thesis, Virginia Tech, 2006. http://hdl.handle.net/10919/34004.

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Mycobacterium avium is human and animal opportunistic pathogen responsible for disseminated disease in immunocompromised patients. Mycobacteria have a capacity to adapt to the environmental conditions by inducing enzyme activities and altering their metabolism. M. avium A5 cells were grown in a defined minimal medium (Nitrogen Test Medium) with glutamine, nitrite, nitrate, or ammonia as sole nitrogen source at a concentration of 2 mM at 370C aerobically. The strain grew well on all the nitrogen sources except nitrite. It grew slowly on nitrite with a generation time of 6 days and cultures were not viable after 4 weeks of storage. These data confirm that M. avium can utilize a single nitrogen source in a defined minimal medium as documented by McCarthy (1987).

M. avium genome has been sequenced and contains genes sharing sequence similarities to respiratory nitrate reductase and dissimilatory nitrite reductases. Because, M. avium can use nitrate or nitrite as sole nitrogen source for growth (McCarthy, 1987), it must have assimilatory nitrate- and nitrite-reductases. Nitrate- and nitrite-reductase activities of M. avium cells growing aerobically or undergoing anaerobic shift in the presence of ammonia, nitrate or ammonia and nitrate in combination were measured. M. avium produced nitrate- as well as nitrite-reductase activity. Nitrite- and nitrate-reductases used either NADH or NADPH as an electron donor. Nitrite reductase activity was greater than nitrate reductase activity. This observation supports the rapid reduction of nitrite and slow reduction of nitrate in M. avium as documented by McCarthy (1987) and explained why M. avium gives a negative result by the standard nitrate reductase test. In addition to assimilatory enzyme activity, M. avium A5 also produced dissimilatory nitrate- and nitrite-reductase activities.
Master of Science

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29

Duncan, Callum William. "Microbial reduction of nitrate to nitrite in the mouth." Thesis, University of Aberdeen, 1999. http://digitool.abdn.ac.uk/R?func=search-advanced-go&find_code1=WSN&request1=AAIU118087.

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The aim of this thesis is to determine the mechanisms by which nitrate is reduced to nitrite in the oral cavity and to investigate how these are modulated by environmental, bacteriological and dietary factors in several mammalian species. The rationale is to determine how this system can be augmented to prevent gastrointestinal diseases in humans and other animals. Experiments using chlorate, as an inhibitor of nitrite production, demonstrated that membrane-bound respiratory nitrate reductase enzymes are responsible for nitrate reduction in the mouth. A significant positive correlation was found between nitrite production and nitrite producing bacterial numbers. These bacteria reside in niches that appear to have evolved specifically to provide a low oxygen environment allowing nitrate respiration. Indeed, nitrite production on the tongue dorsum was shown to be sensitive to oxygen tension. Nitrite producing bacteria had colonised the tongues of newborn rats by 4 days of age and adult levels of nitrate reductase activity were achieved by weaning. Thus, protection against enteric pathogens develops from an early age. Rats and pigs reared in a very "clean" environment had a much lower capacity to produce nitrite than animals exposed to a larger and more diverse microbial flora. Exposure to a high nitrate diet markedly enhanced oral nitrite production. In conclusion the present work shows that nitrate is reduced to nitrite in the oral cavity by symbolic nitrate-reducing facultatively anaerobic staphylococci, using respiratory membrane-bound nitrate reductase. These bacteria reside in specific areas of the oral cavity. This capacity is acquired from an early age and is dependent on the rearing conditions so that free-range animals have a more active nitrite production, particularly if they consume a high nitrate diet. The results presented in this thesis can be used to set up a large scale animal trial to determine the antimicrobial effect in vivo.

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30

Isbell, T. Scott. "Nitrite conversion to nitric oxide biological mechaisms and therapeutic implications /." Thesis, Birmingham, Ala. : University of Alabama at Birmingham, 2007. https://www.mhsl.uab.edu/dt/2009r/isbell.pdf.

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31

Sohlberg, Thomas. "Biologisk reducering av nitrat och nitrit i vatten." Thesis, Karlstad University, Faculty of Technology and Science, 2007. http://urn.kb.se/resolve?urn=urn:nbn:se:kau:diva-2941.

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During the summer 2007 was a scrubber tested at Gruvön papper mill in Grums. The scrubber reduced NO_x with 90 % in flue gas. NO_x was transferred from the flue gas to a scrubber liquid as nitrate and nitrite. The scrubber liquid needs to be purified from nitrate and nitrite.

One possible solution is to clean the scrubber liquid in Gruvön biologic cleaning construction.

Microorganisms in the biologic cleaning construction need to assimilate nitrogen. There are environments free from oxygen in the cleaning construction. Microorganisms can reduce nitrate in environments free from oxygen.

At the implementation was a labmodel built of the two first steps from Gruvön papper mill. Wastewater was collected from Gruvön papper mill. The wastewater was dosed with salts of nitrate and nitrite and pumped into the labmodel.

The results showed that nitrate and nitrite can be reduced in content with help of the biological cleaning construction.

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32

Dias, Cristina Isabel Barata. "Avaliação microbiológica e físico-química de três tipos de enchidos com e sem a adição de aditivos alimentares." Master's thesis, Universidade de Lisboa, Faculdade de Medicina Veterinária, 2018. http://hdl.handle.net/10400.5/15361.

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Dissertação de Mestrado em Segurança Alimentar
Este trabalho teve como objetivo avaliar e comparar as características microbiológicas e físico-químicas de alguns enchidos portugueses, nomeadamente Chouriço da Beira Baixa, Mouro e Farinheira, nos quais o aspeto diferenciador é a utilização ou não de fórmulas de aditivos alimentares próprios para produtos cárneos. Foram realizadas análises microbiológicas e físico-químicas. As análises efetuadas foram contagens de Aeróbios totais a 30 ºC, de Enterobacteriaceae, de bolores e leveduras, medição da atmosfera protetora, determinação da cor, do pH, da aw, do teor de cloretos, do teor de nitritos, do teor de nitratos e do teor total de fósforo. Os resultados microbiológicos indicaram uma maior contagem de Aeróbios totais no grupo de enchidos em que não houve adição de aditivos e a contagem de bactérias da família Enterobactericeae foi baixa em todas as amostras. Os valores de aw e pH obtidos para ambos os grupos em estudo foram elevados. O aw foi superior a 0,90, mas o grupo de enchidos com adição de aditivos apresentou valores de aw ligeiramente superiores. O teor de cloretos e o teor de fósforo obtidos foram superiores no grupo de enchidos em que foram adicionados aditivos. O teor de nitratos e nitritos nas amostras em análise foram muito inferiores aos limites permitidos por lei.
ABSTRACT - The main objective of the present work is evaluates and compare the microbiological and physic-chemical characteristics of some Portuguese sausages, namely “Chouriço da Beira Baixa”, “Mouro” e “Farinheira” in which the differentiating aspect is the use or not of formulas of food additives suitable for meat products. Microbiological and physicochemical analyzes were performed. The analyzes were Total Aerobic at 30 ° C, Enterobacteriaceae, and molds and yeasts counts, the % O2 and CO2 was measured being determined protective atmosphere, color, pH, aw, chloride content, nitrite and nitrate content, and total phosphorus content. Microbiological results indicated a higher total Aerobic count in the group of sausages in which there was no addition of additives and the count of Enterobactericeae was low. The aw and pH values obtained for both groups were high. The aw was higher than 0,90, but group of sausages with addition of additives the aw value observed was slightly higher. The chloride and phosphorus content obtained were higher in the group of sausages in which additives were added. The levels of nitrates and nitrites were much lower than the limits allowed by law.

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Lemos, Sahra Cavalcante [UNESP]. "Desenvolvimento de metodologia alternativa limpa para análise de nitrito." Universidade Estadual Paulista (UNESP), 2008. http://hdl.handle.net/11449/97860.

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Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)
Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES)
O presente trabalho propõe um novo método para análise de nitrito em amostras de águas naturais e alimentos, por espectroscopia de reflectância difusa combinada com spot test. Neste método, a reação de interesse é procedida em papel de filtro, por meio da adição de 30 μL da solução do reagente cromogênico, seguida da adição de 30 μL da solução de analito. A intensidade da coloração do produto é medida por reflectância difusa, em 532 nm. O desenvolvimento do método passou por uma etapa de planejamento experimental, que permitiu encontrar as concentrações ótimas dos reagentes, para as quais a sensibilidade do método é maior (9,60 × 10-3 mol L-1 para o dicloridrato de naftiletilenodiamina e 5,90 × 10-2 mol L-1 para o ácido sulfanílico). O reagente cromogênico foi preparado misturando-se os dois compostos em uma mesma solução, juntamente com ácido clorídrico, na concentração de 6,00 x 10-2 mol L-1. Uma relação linear (r = 0,997) foi observada na faixa entre 2,90 × 10-4 e 1,74 × 10-3 mol L-1 de ânions nitrito, representando os valores de reflectância obtidos versus o logaritmo da concentração de nitrito. Com o objetivo de trabalhar com quantidades ainda menores do analito, as concentrações dos reagentes cromogênicos foram reduzidas pela metade, exceto a do ácido clorídrico, que permaneceu constante, e uma segunda curva analítica (r = 0,997) foi construída na faixa entre 7,17 x 10-6 e 4,35 x 10-4 mol L-1 de íons nitrito, representando-se graficamente os valores de reflectância obtidos versus a concentração de analito presente nas soluções. O produto colorido mostrou uma estabilidade óptica de pelo menos 50 minutos em atmosfera ambiente e de três dias, se mantido em dessecador com atmosfera de nitrogênio. O método apresentou bons valores de precisão intradia e interdia, com RSD iguais...
This work proposes a new method for nitrite determination in natural waters and foodstuff samples by diffuse reflectance spectroscopy combined with spot tests. In this method, the reaction occurs on the surface of a filter paper. Firstly 30 μL of the cromogenic reagent solution were added to the paper, followed by 30 μL of sample solution. The intensity of the color of the reaction product is measured by diffuse reflectance, at 532 nm. Experimental design was employed for the development of this method and the optimized reagent concentrations found were 9.60 × 10-3 mol L-1 for N-(1-naphtil)ethylenediamine hydrochloride and 5.90 × 10-2 mol L-1 for sulfanilic acid. The cromogenic solution was composed by the mixture of both reagents with HCl 6.00 x 10-2 mol L-1, in deionized water. A linear relationship (r = 0.997) was observed in the concentration range of 2.90 × 10-4 to 1.74 × 10-3 mol L-1 of nitrite, by plotting reflectance values versus the logarithm of nitrite concentration in the standard solutions. In order to work with lower quantities of nitrite, the concentrations of sulfanilic acid and N-(1-naphtil)ethylenediamine hydrochloride were diluted to a half of the concentrations proposed by the experimental design. The calibration curve constructed under these conditions showed a linear relationship (r = 0.997) ranging from 7.17 x 10-6 to 4.35 x 10-4 mol L-1 of nitrite ions, by plotting reflectance values versus the concentration of nitrite standard solutions. The colored product had an optical stability of at least 50 minutes in ambient conditions and of three days when kept under nitrogen atmosphere. In the investigation of intraday and iterday precision, the RSD values obtained were 1.51% and 2.01%, respectively. The new method was applied to the analysis of two samples of natural waters and one sausage sample. The results obtained 9 by the proposed method were compared with... (Complete abstract click electronic access below)

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34

Nunes, Tallita Karolline. "Desenvolvimento de salsicha isenta de nitrato e nitrito com atividade de água reduzida = Development of sausage free of nitrate and nitrite and with water activity reduced / Tallita Karoline Nunes ; orientadora, Laura B. Karam ; co-orientador Nery N. de Lima." reponame:Biblioteca Digital de Teses e Dissertações da PUC_PR, 2011. http://www.biblioteca.pucpr.br/tede/tde_busca/arquivo.php?codArquivo=2288.

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Dissertação (mestrado) - Pontifícia Universidade Católica do Paraná, São José dos Pinhais, 2011
Bibliografia: f. 79-82
Os nitratos e nitritos são os principais agentes químicos utilizados na conservação de salsicha, derivado cárneo muito popular em diversas culturas. Apesar das importantes funções tecnológicas em produtos cárneos curados, a aplicação desses conservantes p
Nitrite and Nitrate are the principal chemical agents for preservation of sausage, which is a meat product very famous in different cultures. Although the important technologies functions in cooked-cured meat products, the application of these preservativ

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35

Madrasi, Kumpal J. "Preservation of Nitric Oxide Availability as Nitrite and Nitrosothiols." FIU Digital Commons, 2012. http://digitalcommons.fiu.edu/etd/805.

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Nitric Oxide (NO) has been known for long to regulate vessel tone. However, the close proximity of the site of NO production to “sinks” of NO such as hemoglobin (Hb) in blood suggest that blood will scavenge most of the NO produced. Therefore, it is unclear how NO is able to play its physiological roles. The current study deals with means by which this could be understood. Towards studying the role of nitrosothiols and nitrite in preserving NO availability, a study of the kinetics of glutathione (GSH) nitrosation by NO donors in aerated buffered solutions was undertaken first. Results suggest an increase in the rate of the corresponding nitrosothiol (GSNO) formation with an increase in GSH with a half-maximum constant EC50 that depends on NO concentration, thus indicating a significant contribution of ∙NO2 mediated nitrosation in the production of GSNO. Next, the ability of nitrite to be reduced to NO in the smooth muscle cells was evaluated. The NO formed was inhibited by sGC inhibitors and accelerated by activators and was independent of O2 concentration. Nitrite transport mechanisms and effects of exogenous nitrate on transport and reduction of nitrite were examined. The results showed that sGC can mediate nitrite reduction to NO and nitrite is transported across the smooth muscle cell membrane via anion channels, both of which can be attenuated by nitrate. Finally, a 2 – D axisymmetric diffusion model was constructed to test the accumulation of NO in the smooth muscle layer from reduction of nitrite. It was observed that at the end of the simulation period with physiological concentrations of nitrite in the smooth muscle cells (SMC), a low sustained NO generated from nitrite reduction could maintain significant sGC activity and might affect vessel tone. The major nitrosating mechanism in the circulation at reduced O2 levels was found to be anaerobic and a Cu+ dependent GSNO reduction activity was found to deliver minor amounts of NO from physiological GSNO levels in the tissue.

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36

Sindelar, Jeffrey Joseph. "Investigating uncured no nitrate or nitrite added processed meat products." [Ames, Iowa : Iowa State University], 2006.

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37

Oldreive, Ceri Ellen. "Reactive nitrogen species : the relevance of dietary nitrate and nitrite." Thesis, King's College London (University of London), 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.344088.

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Zazaitė, Gitana. "Ūkininkavimo įtaka šachtinių šulinių vandens kokybei." Master's thesis, Lithuanian Academic Libraries Network (LABT), 2007. http://vddb.library.lt/obj/LT-eLABa-0001:E.02~2007~D_20070816_153513-10951.

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Magistro darbe yra tiriama Kauno rajone, Mitkūnų kaime esančių 5 šachtinių šulinių vandens užterštumas azoto junginiais ir organinėmis medžiagomis. Darbo objektas – šachtinių šulinių vandens kokybės parametrai: nitratai (NO3ˉ ), nitritai (NO2ˉ ), permanganatinė oksidacija (ChDSMn), pH. Darbo tikslas – įvertinti ūkininkavimo įtaką geriamo vandens kokybei ir ryšio tarp sodybos dirbtinių vandens telkinių ir šachtinių šulinių vandens kokybės nustatymas.. Darbo metodai – mokslinės literatūros analizė; cheminės vandens kokybės parametrų kiekybiniai analizės metodai; statistinė analizė, panaudojant EXCEL ir STATISTCA programinius paketus. Darbo rezultatai :atlikus tyrimus nustatyta, kad vanduo užterštas nitratais. Šachtinių šulinių vandens kokybės kitimui būdinga sezoninė tarša.
Subject of research – shallows water quality indicators: nitrate (NO3ֿ), nitrite (NO2ֿ), organic matter (ChDSMn), water pH. Aim of research – to evaluate farming influence of drinking water quality and contact between homestead pond and shallows water quality. Methodology – analysis of scientific literature; chemical water quality analizes methods; statistical analysis using EXCEL, STATISTICA programs. Results of research – the results of scientific research showed, that water is polluted with nitrate. The tendency of water quality variations during seasons was observed.

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Kotur, Zorica. "Characterization of high-affinity nitrate and nitrite transporters in Arabidopsis thaliana." Thesis, University of British Columbia, 2013. http://hdl.handle.net/2429/45124.

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40

Kummer, Ana Carolina Barbosa. "Desnitrificação de efluente de abatedouro de tilápia utilizando manipueira como fonte de carbono." Universidade Estadual do Oeste do Parana, 2008. http://tede.unioeste.br:8080/tede/handle/tede/282.

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Fundação Araucária
The processing fish industry is responsible for the production of high amounts of wastewater, rich in organic matter, grease and high concentration of nitrogen, so, conventional use of primary and secondary treatment is not enough to reach the standard demand from the environmental agencies. Consequently, it is necessary the application of wastewater treatment techniques to reduce the impacts produced by those effluents on the environment. The biological treatment of nitrogen compounds has been an alternative to improve their quality. One of the biological processes is based on nitrification followed by denitrification, where oxidized compounds by nitrogen are transformed in molecular nitrogen that rises to the atmosphere. This trial aimed at checking the denitrification of tilápia wastewater from slaughterhouse, in a batch reactor. So, the wastewater from a cassava processing industry (manipueira) was evaluated as a carbon source, as well as the shaking conditions of the process. The experiments were carried out in laboratory series. Five shaking levels were tested (20; 32; 60; 88 e 100 rpm) as well as five COD/N ratio levels (0.1; 1.0; 3.2; 5.4 and 6.3), forming a planning as a Central Composite Rotational Design (CCRD), with four essays in levels +1 and -1; four essays on the axial points levels (-1.414 and +1.414) and one more triplicate in the central point (0), which meant 11 (eleven) essays. The denitrification performance through the nitrate removal (%) and COD removal (%) were evaluated. During this process, temperature (°C), pH and alkalinity (mgCaCO3.L-1) were also observed. The results showed that the COD/N ratio had significant influence, with a 95 % of confidence interval on the process of nitrate and nitrite removal, with a great operation range, from 3.2 to 5.4, whose nitrogen removal efficiencies were 100 %. On the other hand, shaking did not have a significant effect on the process.
A indústria processadora de peixe caracteriza-se por gerar elevadas quantidades de efluentes, ricos em matéria orgânica, gorduras e concentração de nitrogênio. Consequentemente, apenas o emprego de tratamentos primário e secundário convencionais não é suficiente para atingir os padrões exigidos pelos órgãos ambientais. Desta forma, faz-se necessário o emprego de técnicas de tratamento de efluentes que minimizem os impactos gerados por esses no meio ambiente. O tratamento biológico dos compostos nitrogenados tem sido uma alternativa para melhorar a qualidade dos efluentes. Um dos processos biológicos constitui-se na nitrificação seguida da desnitrificação, em que os compostos oxidados de nitrogênio são, então, transformados em nitrogênio gasoso que é devolvido à atmosfera. O objetivo deste trabalho foi a desnitrificação de efluente de abatedouro de tilápia, em reator em batelada. Para isto, foi avaliado o efluente gerado por uma indústria processadora de mandioca (manipueira) como fonte de carbono. Também foram avaliadas as condições de agitação do sistema. Os experimentos foram conduzidos em escala de laboratório, em que foram testados cinco níveis de agitação (20; 32; 60; 88 e 100 rpm) e cinco freqüências da relação DQO/N (0,1; 1,0; 3,2; 5,4 e 6,3), configurando-se um planejamento do tipo Delineamento Composto Central Rotacional (DCCR), com quatro ensaios nos níveis +1 e -1; quatro ensaios nos níveis dos pontos axiais (-1,414 e +1,414) e mais uma triplicata no ponto central (0), totalizando 11 ensaios. Avaliaram-se o desempenho da desnitrificação através da remoção de nitrato (%), a remoção de nitrito (%) e a remoção de DQO (%). Durante o processo também foram monitorados temperatura (ºC), pH, e alcalinidade (mgCaCO3.L-1). Os resultados mostraram que a relação DQO/N teve influência significativa, com intervalo de confiança de 95 % sobre o processo de remoção de nitrato e nitrito, com faixa ótima de operação entre 3,2 e 5,4, cujas eficiências de remoção de nitrogênio foram de 100%. Contudo, a agitação não teve efeito significativo sobre o processo.

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41

Vacek, Petr. "Rozsáhlé defekty v nitridech Ga a Al." Doctoral thesis, Vysoké učení technické v Brně. CEITEC VUT, 2021. http://www.nusl.cz/ntk/nusl-447553.

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III-nitridy běžně krystalizují v hexagonální (wurtzitové) struktuře, zatímco kubická (sfaleritová) struktura je metastabilní a má pouze mírně vyšší energii. Jejich fyzikální vlastnosti jsou silně ovlivněny přítomností rozsáhlých defektů, které jsou v těchto dvou strukturách od sebe odlišné. U wurtzitových nitridů se jedná primárně o vláknové dislokace. Některé vláknové dislokace tvoří hluboké energetické stavy v zakázaném pásu, kterými ovlivňují elektrické a optoelektronické vlastnosti těchto materiálů. Oproti tomu, kubické nitridy obsahují množství vrstevných chyb, které představují lokální transformace do stabilnější wurtzitové struktury. Cílem této práce je charakterizovat rozsáhlé defekty v obou krystalových strukturách pomocí elektronové mikroskopie, mikroskopie atomárních sil a rentgenové difrakce. Prokázali jsme, že vzorky GaN/AlN a AlN s orientací (0001) rostlé na substrátu Si (111) pomocí epitaxe z organokovových sloučenin obsahují velkou hustotu vláknových dislokací. Nejčastější jsou dislokace s Burgersovým vektorem s komponentou ve směru a wurtzitové struktury, následované dislokacemi s Burgersovým vektorem s komponentou ve směru a+c, zatímco dislokace s Burgersovým vektorem s c komponentou jsou relativně vzácné. Pravděpodobný původ vláknových dislokací je diskutován v souvislosti s různými mechanismy růstu těchto vrstev. Prizmatické vrstevné chyby byly nalezeny v tenkých nukleačních vrstvách AlN, ale v tlustších vrstvách již nebyly přítomny. Na rozhraní AlN / Si byla nalezena amorfní vrstva složená ze SiNx a částečně taky z AlN. Navrhujeme, že by tato amorfní vrstva mohla hrát významnou roli při relaxaci misfitového napětí. Analýza elektrické aktivity rozsáhlých defektů v AlN byla provedena pomocí měření proudu indukovaného elektronovým svazkem. Zjistili jsme, že vláknové dislokace způsobují slabý pokles indukovaného proudu. Díky jejich vysoké hustotě a rovnoměrnému rozložení však mají větší vliv na elektrické vlastnosti, než mají V-defekty a jejich shluky. Topografické a krystalografické defekty byly studovány na nežíhaných a žíhaných nukleačních vrstvách kubického GaN deponovaných na 3C-SiC (001) / Si (001) substrátu. Velikost ostrůvků na nežíhaných vzorcích se zvyšuje s tloušťkou nukleační vrstvy a po žíhání se dále zvětšuje. Po žíhání se snižuje pokrytí substrátu u nejtenčích nukleačních vrstev v důsledku difúze a desorpce (nebo leptání atmosférou reaktoru). Vrstevné chyby nalezené ve vrstvách GaN, poblíž rozhraní se SiC, byly většinou identifikovány jako intrinsické a byly ohraničené Shockleyho parciálními dislokacemi. Jejich původ byl diskutován, jako i vliv parciálních dislokací na relaxaci misfitového napětí. Díky velkému množství vrstevných chyb byly podrobněji studovány jejich interakce. Na základě našich zjištění jsme vyvinuli teoretický model popisující anihilaci vrstevných chyb v kubických vrstvách GaN. Tento model dokáže předpovědět pokles hustoty vrstevných chyb se zvyšující se tloušťkou vrstvy.

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42

Fletgen, Marie Christine. "Le devenir des nitrates et des nitrites dans l'organisme humain et leur danger potentiel : problème des nitrosamines." Paris 5, 1992. http://www.theses.fr/1992PA05P241.

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Rhodes, Peter. "Indices of nitric oxide production." Thesis, University of Cambridge, 1995. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.307982.

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44

Yang, Shu. "Electrocatalytic reduction of NOx on metal nanoparticles stabilized by polyoxometalates." Thesis, Strasbourg, 2017. http://www.theses.fr/2017STRAF056.

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L’objet de ce travail est de développer des nouveaux catalyseurs pour réduire les ions nitrites (NO2- /HNO2) et nitrates (NO3-) dans l’eau en étudiant les facteurs qui vont influencer leurs réductions catalytiques. On a montré que la présence de polyoxométallates (POMs) permet d’améliorer les propriétés catalytiques de l’électrode de Cu et d’Ag pour la réduction de ions nitrate et nitrite avec des conditions adaptées. Par la suite, des nanoparticules du cuivre (Cu@POM) ou d’argent (Ag@POM) ont été préparées par électroréduction of CuPOM in situ ou photocatalyse en présence d’ions POMs et Ag(I) respectivement. Leurs propriétés électrocatalytiques ont été étudiées. Six différents polyoxométallates substitués par des atomes de Cu(II) (CuPOMs) ont montré de bonnes activités pour la réduction de nitrite à pH 1 et à pH 5. Deux activités sont observées : au potentiel de la réduction de CuII et au potentiel de réduction des W(VI) du POM. Quant à la réduction du nitrate, [Cu4(H2O)2(P2W15O56)2]16- et [(A-β-SiW9O34)Cu4(OH)3(H2O)(H3N(CH2)3COO)2]3 5- peuvent catalyser la réduction du nitrate à un potentiel au-delà de la réduction du Cu(II) à la réduction des W(VI). Par contre, dans le cas de [(SbW9O33)2{Cu(H2O)}3]12– aucune électrocatalyse n’est observée. Cela indique que le type de POM influence les propriétés catalytiques des nanoparticules. Pour le système Ag@POM photoréduit, un catalyseur hétérogène est préparé et stabilisé par une couche de Nafion. Les nanoparticules Ag@POM sont actives pour la réduction du nitrite et du nitrate et possèdent une activité meilleure que celle mesurée pour l’électrode d’Ag seule. Dans la dernière partie, une étude préliminaire de polyoxométallates encapsulés dans les ‘Metal-Organic Framworks’ (MOFs) e st présentée. L’entité POM conserve ses propriétés électrochimiques et électrocatalytiques pour la réduction de nitrite après immobilisation dans la cage MOF
The object of this work is to develop new catalysts to reduce nitrite ions (NO2- / HNO2) and nitrate ions(NO3-) in water and also tried to understand the factors that will influence catalytic reductions. It has been shown that the presence of polyoxometalates makes it possible to improve the catalytic properties of the Cu and Ag bulk electrodes for the reduction of nitrate and nitrite ions under suitable conditions. Then, the copper or silver nanoparticles decorated with POMs, Cu@POM or Ag@POM), are formed with two different methods: electroreduction in situ of CuPOM or photocatalysis in the presence of POM and Ag(I) ions respectively). Their electrocatalytic properties are presented. Six different Cusubstituted polyoxometalates (CuPOMs) are active for nitrite reduction at pH 1 and pH 5. Two activities are observed at the potential of CuII reduction and at the potential of WVI reduction in POM. [Cu4(H2O)2(P2W15O56)2]16- and [(A-β-SiW9O34)Cu4(OH)3(H2O)(H3N(CH2)3COO)2]3 5- catalyse the nitrate reduction at the potential beyond the reduction of CuII and at the reduction of WVI. On the other hand, no catalysis efficiency was observed with [(SbW9O33)2{Cu(H2O)}3]12-. This indicates the type of POM will influence the catalytic properties of nanoparticles. With the photoreduced Ag@POM nanoparticles, a heterogeneous catalyst is prepared and stabilized by a Nafion layer. Ag@POM nanoparticles are active for the reduction of nitrite and nitrate and have an activity better than the Ag electrode alone. In the last part, a preliminary study of polyoxometalates encapsulated in Metal-Organic Framworks (MOFs) is presented. POM retains its electrochemical and electrocatalytic properties toward the reduction of nitrite after immobilized in the cage of MOF

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Adami, Fernanda Scherer. "Teor de nitrato e nitrito e análise microbiológica em linguiças e queijos." reponame:Repositório Institucional da UNIVATES, 2015. http://hdl.handle.net/10737/985.

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A utilização de sais de nitrato e nitrito em produtos cárneos é secular e, com a evolução das técnicas de conservação alimentar, estes vêm sendo cada dia mais utilizados, pois melhoram o sabor e a cor. Os objetivos deste estudo foram realizar análises microbiológicas, de atividade de água, pH, concentração de nitritos e nitratos presentes em amostras de linguiças (tipo mistos e suínos) com Inspeção do Serviço Municipal e queijos (tipo colonial e prato), fiscalizados pelos Serviços de Inspeção Municipal e Estadual, produzidos na região do Vale do Taquari, Rio Grande do Sul. As amostras de queijos Prato (n=14) e Colonial (n=10) foram adquiridas diretamente nas indústrias com Inspeção Sanitária Municipal (n=11) e Estadual (n=13), produzidas em municípios do Vale Taquari durante os meses de abril, maio e junho de 2013. Para a coleta das amostras houve o cuidado de mantê-las íntegras, com o mínimo de contato ou manipulação. As amostras de linguiça foram coletadas em 11 estabelecimentos fiscalizados pelo Sistema de Inspeção Municipal (SIM). Os teores residuais de nitratos e nitritos, pH e atividade de água das amostras foram avaliados segundo as metodologias analíticas oficiais previstas na Instrução Normativa n° 20, de 21 de julho de 1999, do Ministério da Agricultura, Pecuária e Abastecimento (MAPA). As análises microbiológicas foram realizadas em laboratório certificado no Ministério da Agricultura (MAPA), na Rede Metrológica do Rio Grande do Sul, cadastrado na Fundação Estadual de Proteção Ambiental (FEPAM) e com ISO 17025. As concentrações de nitrato e nitrito encontradas acima do recomendado pela legislação nas amostras foram de 33,3% (p=0,030) e 100% (p<0,001), respectivamente. Em 41,7% (n=10) e 25% (n=6) do total das amostras de queijo foram encontrados índices de contaminação por coliformes termotolerantes e Staphylococcus coagulase positiva acima do preconizado pela legislação, respectivamente, contudo não foi verificada diferença significativa para os valores encontrados em relação ao valor de referência, e 100% das amostras de queijo estavam isentas de Salmonella spp. Em relação as linguiças, 30,3% das amostras apresentaram teor de nitrito e 69,7% apresentaram teor de nitrato acima do previsto pela legislação brasileira. As médias de atividade de água e do teor de nitrato apresentaram-se significativamente acima do valor de referência. Enquanto as médias de pH não demonstrou diferença significativa em relação ao valor de referência e a média de nitrito apresentou-se inferior a legislação, mas com elevado desvio padrão. Conclui-se que a totalidade das amostras de queijo analisadas neste estudo apresentou concentrações acima do recomendado pela legislação para nitrito e um terço apresentou-se não conforme em relação à concentração de nitrato. Sobre a linguiça, foi observada inadequação ao que é determinado pela legislação brasileira em relação à quantidade de nitrito e nitrato, parâmetros microbiológicos de coliformes termotolerantes, Staphylococcus coagulase positiva e Salmonella spp., atividade de água, e adequação em relação ao pH.
The use of nitrate and nitrite salts in meat products is centuries old and with the development of food preservation techniques they are being more used every day because it improves flavor and color. The objective of this study were to perform the microbiological analysis, and also analysis of water activity, pH, concentration of nitrites and nitrates in sausage samples (mixed type and pigs) with inspection of the Municipal Service, and cheese (colonial type and plate), supervised by Service Municipal and State Inspection, produced in the region of Vale do Taquari, Rio Grande do Sul. The sample of plate cheese (n=14) and colonial (n=10) were acquired directly in industries with Municipal Sanitary Inspection (n=11) and State (n=13), produced in municipalities in the Taquari Valley during the months of April, May and June 2013. The samples were collected with care to keep them intact and a minimal contact or manipulation. The sausage samples were collected from 11 establishments inspected by the Municipal Inspection System. The samples' residual levels of nitrates and nitrites, pH and water activity were evaluated according to the official analytical methods provided by the Normative Ruling No. 20 of July 21, 1999, of Ministry of Agriculture, Livestock and Supply. The microbiological analyzes were performed in laboratory certified by Ministry of Agriculture in the Metrology Network of Rio Grande do Sul, registered in the State Environmental Protection Foundation, with ISO 17025. The nitrate and nitrite concentrations found above the recommended by the legislation in the samples was 33.3% (p=0.030) and 100% (p <0.001), respectively. In 41.7% (n = 10) and 25% (n = 6) of the total samples of cheese contamination rates were found by thermotolerant coliform and Staphylococcus coagulase positive above recommended by law, respectively, but there was no significant difference to those found in relation to the reference value and 100% of cheese samples were free of Salmonella spp. In relation to the sausages, 30.3% of the samples had nitrite content and 69.7% had nitrate levels higher than expected by Brazilian law. The average of water activity and nitrate levels were significantly above the reference value. While the average of pH showed no significant difference from the reference value and the nitrite average has performed under law, but with high standard deviation. It is concluded that all the cheese samples analyzed in this study had higher concentrations than recommended by law for nitrite and a third it is not in accordance to the concentration of nitrate. Regarding the sausage, it was observed inadequacy in relation to what is required by Brazilian law in relation to the amount of nitrite and nitrate, microbiological parameters of thermotolerant coliform, Staphylococcus coagulase positive and Salmonella spp., water activity and suitability in relation to the pH.

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46

Siriwatcharapiboon, Wilai. "The electrochemistry of metal nanoparticles for oxygen reduction and nitrate/nitrite reduction." Thesis, University of Birmingham, 2013. http://etheses.bham.ac.uk//id/eprint/4475/.

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This research has scientific aims focused on two important electrochemical reactions: oxygen reduction and nitrate/nitrite reduction. A series of rhodium (Rh) deposited on gold nanorods (Au NRs) and gold nanoparticles (Au NPs) were synthesised by wet chemical reduction. The scanning transmission electron microscopy (STEM) showed that Rh has a preferential deposition and epitaxial growth at the end of Au NRs. Cyclic voltammetry and rotating disc electrode (RDE) measurements were performed to study the oxygen reduction at these Au:Rh/C catalysts. Pyrolysed cobalt triethylenetetraamine on a carbon substrate (Co/TET A/C) was employed to produce H20 2 from the ORR. The results from the rotating ring disc electrode (RRDE) reveal that the heat treatment influences the H20 2 selectivity. The Co/TETA/C heated at 1000 oc yields the highest H20 2 selectivity while the Co/TETA/C heated at 700 oc yields the lowest H20 2 selectivity. Rh/C, Au:Rh/C nanoparticles and Sn modified Rh/C nanoparticles were employed for nitrate/nitrite reduction in acidic media. Results from on-line electrochemical mass spectrometry (OLEMS) reveal that the modified electrode generates N2 from further reduction of the nitrous oxide (N20) intermediate. Ion chromatography (IC) shows that ammonium is the main product at Rh/C. Hydroxylamine can also be detected after Sn modification on Rh/C.

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Maan, Neeti. "i-Nitrite Therapy for Treatment of Peripheral Arterial Disease." Case Western Reserve University School of Graduate Studies / OhioLINK, 2012. http://rave.ohiolink.edu/etdc/view?acc_num=case1339162099.

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Braun, Cordula. "Neue Hochdruckphasen der Nitrido- und Oxonitridosilicate und verwandter binärer Nitride." Diss., lmu, 2010. http://nbn-resolving.de/urn:nbn:de:bvb:19-136960.

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Chauret, Christian. "Effect of tungsten on nitrate and nitrite reductases in Azospirillum brasilense SP 7." Thesis, McGill University, 1990. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=59635.

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Azospirillum brasilense reduced nitrate in W-containing Mo-limited medium, but at lower rates than in W-free medium. However nitrate reduction by Paracoccus denitrificans was completely suppressed under the same conditions. Nitrite reductase activity of growing A. brasilense was negatively affected by tungstate. Nitrite accumulation was shown to be the result of an inhibitory effect of nitrate on nitrite reductase activity. Both resting whole cell and cell-free extract preformed nitrite reductase activities were equally affected by increasing levels of tungstate. Preformed nitrate reductase activity of the cell-free extract was shown to be more sensitive to increasing concentrations of tungstate than whole cell activity, suggesting that the cytoplasmic membrane served as a protective barrier against tungsten inactivation of nitrate reductase.

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50

Tang, Abraham H. "Study of nitrate regulatory elements and their response to nitrite in Arabidopsis thaliana." Diss., [La Jolla] : University of California, San Diego, 2010. http://wwwlib.umi.com/cr/fullcit?p1477938.

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Thesis (M.S.)--University of California, San Diego, 2010.
Title from first page of PDF file (viewed July 16, 2010). Available via ProQuest Digital Dissertations. Vita. Includes bibliographical references (leaves 34-36).

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Dissertations / Theses on the topic 'Nitrity'

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