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Showing 21 to 30 of 30 (0.041 seconds)| 21 |
Modulations biochimiques de l'activité des canaux K[indice supérieur +] de type GK[indice inférieur Ca] du sarcolemme des muscles lisses des voies respiratoires par le monoxyde d'azoteAlioua, Abderrahmane January 1996 (has links)
Le but de cette étude était d'élucider les mécanismes biochimiques qui régulent les canaux K$\sp+$ de type (GK$\rm\sb{Ca}),$ impliqués dans le contrôle du tonus des muscles lisses des voies respiratoires (MLVR). Des mesures pharmacologiques ont permis de démontrer que le 3-morpholino-sydnonimine (SIN-1) relaxe des fragments de bronches de rat précontractées par 0.2 $\mu$M carbachol, de façon concentration-dépendante. Par contre, lorsque la contribution de la conductance potassique (GK) est éliminée, en présence de 135 mM KCl dans le milieu extracellulaire ou lorsque la guanylate cyclase soluble (GCs) est inhibée par 10 $\mu$M de bleu de méthylène (BM), l'effet relaxant du SIN-1 est moins efficace, ce qui suggère que le monoxyde d'azote (NO$\sp\cdot)\sp*$ pourrait activer plusieurs effecteurs pour induire son effet relaxant via deux voies: une voie dépendante du GMPc et une autre qui serait indépendante de ce messager. Un autre objectif envisagé était de démontrer que le NO avait un effet relaxant indépendant du GMPc, et qu'il pourrait être dû, en partie, à une activation directe des GK$\rm\sb{Ca}.$ Les tests pharmacologiques montrent que 100 nM de charybdotoxine (ChTX), un inhibiteur spécifique des GK$\rm\sb{Ca},$ changent la sensibilité des MLVR au SIN-1 lorsque la GCs est inhibée, ce qui indique que les GK$\rm\sb{Ca}$ pourraient être activées directement par le NO. Ces résultats ont été confirmés au niveau moléculaire, suite à la reconstitution des canaux dans les BLP. Le SIN-1 (NO), mais pas ses métabolites, active les GK$\rm\sb{Ca}$ avec une EC$\sb{50}$ évaluée à 30 $\mu$M SIN-1. Afin de vérifier le mode d'activation direct des GK$\rm\sb{Ca}$ par le NO, des expériences ont été réalisées en présence de 5 mM DTT, un agent réducteur qui empêche le NO d'activer les GK$\rm\sb{Ca},$ seulement lorsqu'il est ajouté du côté intracytoplasmique (trans) du canal. Ces résultats tendent à prouver que l'activation directe des GK$\rm\sb{Ca}$ des MLVR, résulterait d'une interaction du NO avec les groupements des chaînes latérales d'acides aminés, situés sur les boucles intracellulaires de la sous-unité $\alpha,$ selon un mécanisme de nitrosylation**. En revanche, le DTT n'est plus capable de renverser l'effet du NO, ce qui suggère l'implication de d'autres groupements autres que les SH avec lesquels interagit le NO. En conclusion, cette étude a permis de montrer, pour la première fois, que le NO pourrait augmenter la P$\rm\sb{o}$ des canaux K$\sp+$ de type GK$\rm\sb{Ca}$ des MLVR par un mécanisme indirect (phosphorylation) catalysée par la PKG en présence du GMPc et par une interaction directe (nitrosylation) avec la sous-unité $\alpha$ du canal, sans altérer la conductance ni la sensibilité du canal au Ca$\sp{2+}$ et au voltage, ce qui fait de ce type de canal un effecteur sensible et efficace dans le contrôle de la relaxation des MLVR Le NO dans un milieu biologique se trouve dans un état radicalaire NO actif. $\sp{**}$nitrosylation est un terme qui désigne l'interaction covalente entre le NO et les groupements SH des protéines. [Symboles non conformes]
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Adsor??o dos gases NH3, NO e H2S em fosfato de vanadila, hidrogeno fosfato de vanadila e fosfatos de vanadila dopados por Al, Co, Mn e CrMiranda, Jose Carlos Vieira de 31 July 2013 (has links)
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Previous issue date: 2013-07-31 / In this work were synthesized the materials called vanadyl phosphate, hydrogen
vanadyl phosphate and vanadyl phosphate doped by transition metals with the aim in
adsorption the following compounds: ammonia, hydrogen sulfide and nitrogen oxide. To
characterize the starting compounds was used DRX, FTIR, FRX and TG analysis. After the
characterization of substrates, proceeded de adsorption of NH3 and H2S gases in reactor,
passing the gases with continuous flow for 30 min and room temperature. Gravimetric data
indicate that the matrices of higher performance in adsorption of ammonia was those doped
by aluminum and manganese, obtaining results of 216,77 mgNH3/g and 200,40 mgNH3/g of
matrix, respectively. The matrice of higher performance in adsorption of hydrogen sulfide
was that doped by manganese, obtaining results of 86,94 mgH2S/g of matrix. The synthesis of
substrates VOPO4.2H2O and MnVOPO4.2H2O with nitrogen oxide was made in solution,
aiming the final products VOPO4.G.nH2O and MnVOPO4.G.nH2O (G = NO and n = number
of water molecules). The thermo analytical behavior and the infrared spectroscopy are
indicative of formation of VOPO4.2,5NO.3H2O compound. Results of scanning electron
microscopy (SEM) and Energy dispersive spectroscopy (EDS) of materials vanadyl phosphate
and vanadyl phosphate modified after reaction in solid state or in solution with the gases show
morphology changes in substrates, beyond the formation of orthorhombic sulfur crystals over
their respective hosts when these adsorb hydrogen sulfide / Neste trabalho foram sintetizados os materiais denominados fosfato de vanadila,
hidrogeno fosfato de vanadila e fosfatos de vanadila dopados por metais de transi??o com fins
na adsor??o de am?nia, sulfeto de hidrog?nio e ?xido de nitrog?nio. Para a caracteriza??o dos
compostos de partida, recorre-se ?s t?cnicas de DRX, FTIR, FRX e TG. Ap?s a
caracteriza??o dos substratos, procedeu-se a adsor??o dos gases NH3 e H2S em reator,
passando os gases a vaz?o cont?nua durante 30 min e temperatura ambiente. Dados
gravim?tricos indicam que as matrizes de maior desempenho na adsor??o de am?nia foram
?quelas dopadas por alum?nio e mangan?s, obtendo resultado de 216,77 mgNH3/g e 200,40
mgNH3/g de matriz, respectivamente. A matriz de maior desempenho para a adsor??o de
sulfeto de hidrog?nio foi ?quela dopada por mangan?s, obtendo resultado de 86,94 mgH2S/g
de matriz. As s?nteses dos substratos VOPO4.2H2O e MnVOPO4.2H2O com o g?s ?xido de
nitrog?nio foram realizadas em solu??o, objetivando-se os produtos finais VOPO4.G.nH2O e
MnVOPO4.G.nH2O (G = NO e n = n?mero de mol?culas de ?gua). O comportamento
termoanal?tico e a espectroscopia na regi?o do infravermelho s?o indicativos da forma??o do
composto VOPO4.2,5NO.3H2O. Resultados de microscopia eletr?nica de varredura (MEV) e
espectroscopia de energia dispersiva (EDS) dos materiais fosfatos de vanadila e fosfatos de
vanadila dopados ap?s rea??o no estado s?lido ou em solu??o com os gases indicam mudan?a
na morfologia dos substratos, al?m da forma??o de cristais de enxofre ortorr?mbico sobre
seus respectivos hospedeiros quando estes adsorvem sulfeto de hidrog?nio
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N-Radical Injection For Augmenting The Nox Removal In Diesel Engine Exhaust By Electric DischargesSushma, B R 07 1900 (has links) (PDF)
No description available.
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No/Nox Removal In Diesel Engine Exhaust Under Different Energizations And Reactor ConfigurationsKumar, Bijendra 01 1900 (has links)
In India, with the increase in the number of industries and vehicles the environment is getting more and more polluted. More than industries it is the rapid growth of vehicles which causes serious environmental crisis in the form of air pollution and has become alarming particularly in cities. The industrial and vehicular growth cannot be neglected, as the country’s economic and social well being is largely dependent on them. But this should not come at the cost of our health and eco system. The industrial and vehicular emissions must be controlled in order to keep our air clean. Continued efforts in this direction are being taken up across the globe to investigate an efficient and economical technique.
There are many air pollutants being emitted from both natural and manmade sources. The major air pollutants identified as hazardous to human health are nitrogen oxides (NOx), carbon monoxide (CO), particulate matter (PM), volatile organic compounds (VOC), and sulfur dioxides (SOx). Among these, nitrogen oxides are considered to be difficult to remove. The sources of NOx are thermal power plants, stationary and mobile diesel engines, gasturbine engine, ironore sintering plants and various other smallscale utilities. There are conventionally available technologies to remove NOx such as chemical scrubbing, catalysis etc. But these techniques are either difficult to operate or do not bring down the level of NOx to the required norms imposed by the government. The failure of conventional techniques to remove NOx to the expected limit led to the development of alternative nonconventional techniques. Prominent among these new alternative techniques is electric discharge plasma, where the gas is partially ionized and temperature of electrons is considerably higher than that of ions and background gas molecules.
Diesel engines are getting popular due to their inherent merits and their number is increasing considerably. Unfortunately, the exhaust of diesel engine being complex with high oxygen content makes the existing pollution control techniques insufficient particularly with regard to removal of NOx. So there is a need for investigating better technology which can effectively abate the pollutants from diesel engine exhaust. Electric Discharge plasma is one such alternative technique which has been very successful in large volumes of flue gas cleaning and hence, its potential is being explored in the cleaning of small volumes of vehicular exhausts, in particular, diesel engine exhaust.
In the present work we investigated the relative performance of different electric discharge plasma reactors, with different type of voltages like AC, DC and pulse. The reactors were evaluated for NOx removal efficiency and NO conversion. This research work is a feasibility study to find whether electric discharge plasma can be used more effectively as an alternative technology for the after treatment of diesel engine exhaust in cascade with some cheaper adsorbents, if necessary.
The scope of this qualitative experimental study can briefly be summarized as below:
. • To study different reactors for NO conversion and NOx removal
. • To study the effect of dielectric pellets in enhancing the radical production which in turn will have a bearing on the chemical reactions
. • To study the effect of different types of voltages on the cleansing process
. • To propose an efficient reactor system subject to the experimental conditions studied.
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Estudo experimental da formação e emissão do N0x na combustão do etanol e GLP em uma camara de combustão cilindrica / Experimental study of the formation and emission of the N0x in the combustion of ethanol and LPG in a cylindrical combustion chamberLenço, Paulo Cesar 21 December 2004 (has links)
Orientador: Waldir Antonio Bizzo / Dissertação (mestrado) - Universidade Estadual de Campinas, Faculdade de Engenharia Mecanica / Made available in DSpace on 2018-08-06T16:24:43Z (GMT). No. of bitstreams: 1
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Previous issue date: 2004 / Resumo: Com a inovação tecnológica houve um aumento crescente no consumo de energia devido ao aumento das necessidades individuais e coletivas. Isso trouxe a necessidade de criar novas fontes de energia. A utilização intensiva de combustíveis fósseis tem causado o aumento da poluição ambiental e a degradação e escassez de recursos naturais não renováveis. A formação de gases poluentes, tais como oCO, COz, e os NOx, tem causado grande preocupação e contribuído para fenômenos como o aquecimento global ou formação de ozônio atmosférico. Com a crescente emissão desses gases e de compostos nocivos, as alternativas viáveis são as escolhas de combustíveis renováveis e a adoção de mecanismos minimizantes da formação. A formação de óxidos de nitrogênio, através do mecanismo de Zeldovich, é fornecida por altas temperaturas locais e disponibilidade de oxigênio. Estes fatores, por sua vez, sofTem influência da fluidodinâmica da combustão e a distribuição do tempo de residência. Este trabalho estudou a emissão e a formação de NOx e CO em uma câmara de combustão cilíndrica isolada termicamente, queimando GLP (gás liquefeito de petróleo) e etanol vaporizado. Foram utilizadas o mesmo tempo de residência, a mesma potência específica, temperaturas de saída dos gases de 1O00°C e 1175°C, e diversos números de rotação do queimador. Estes dados foram relacionados com a formação do oxido de nitrogênio na câmara de combustão. Em dois números de rotação específicos foram medidas o campo de temperatura e a distribuição de concentração de NOx, CO e O2, no interior da câmara de combustão / Abstract: The technological innovation caused a growing increase in the energy consumption because the individual and collective needs increased. Then it was necessary to create new energy sources. The intensive use of fossil fuels use has caused environmental pollution, besides degradation and shortage of natural resources. The generation of pollutant gases, such as CO, CO2, and NOx, has caused great concem and also has contributed to the global warming or generation of atmospheric ozone. To struggle with the rising emission ofthose gases, viable altematives are using renewable fuels and emission and formation minimization mechanisms. Nitrogen oxides formation, by the Zeldovich mechanism, occurs by high local temperatures and available oxygen. However, these factors are influenced by combustion fluid dynamics and residence time distribution. This work studied emission and formation of NOx and CO in a cylindrical combustion chamber, thermal insulated, buming LPG (Liquefied Petroleum Gas) and vaporized ethanol. In this equipment were used the same residence time, specific power, exit temperatures of gases 1000°C and 1175°C, and severa! swirl numbers at the bumer. These data were related to the nitrogen oxides formation in the combustion chamber. In two specific swirl numbers, the temperature field and the distribution of NOx, CO and O2 concentration were measured, inside the combustion chamber / Mestrado / Termica e Fluidos / Mestre em Engenharia Mecânica
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Electric Discharge Plasma Promoted Adsorption/Catalysis, For Removal Of NOx, HC And CO From An Actual Diesel Engine ExhaustSrinivasan, A D 08 1900 (has links) (PDF)
No description available.
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Oxidation of terpenes in indoor environments : A study of influencing factorsPommer, Linda January 2003 (has links)
In this thesis the oxidation of monoterpenes by O3 and NO2 and factors that influenced the oxidation were studied. In the environment both ozone (O3) and nitrogen dioxide (NO2) are present as oxidising gases, which causes sampling artefacts when using Tenax TA as an adsorbent to sample organic compounds in the air. A scrubber was developed to remove O3 and NO2 prior to the sampling tube, and artefacts during sampling were minimised when using the scrubber. The main organic compounds sampled in this thesis were two monoterpenes, alfa-pinene and delta-3-carene, due to their presence in both indoor and outdoor air. The recovery of the monoterpenes through the scrubber varied between 75-97% at relative humidities of 15-75%. The reactions of alfa-pinene and delta-3-carene with O 3, NO2 and nitric oxide (NO) at different relative humidities (RHs) and reaction times were studied in a dark reaction chamber. The experiments were planned and performed according to an experimental design were the factors influencing the reaction (O3, NO2, NO, RH and reaction times) were varied between high and low levels. In the experiments up to 13% of the monoterpenes reacted when O3, NO2, and reaction time were at high levels, and NO, and RH were at low levels. In the evaluation eight and seven factors (including both single and interaction factors) were found to influence the amount of alfa-pinene and delta-3-carene reacted, respectively. The three most influencing factors for both of the monoterpenes were the O 3 level, the reaction time, and the RH. Increased O3 level and reaction time increased the amount of monoterpene reacted, and increased RH decreased the amount reacted. A theoretical model of the reactions occurring in the reaction chamber was created. The amount of monoterpene reacted at different initial settings of O3, NO2, and NO were calculated, as well as the influence of different reaction pathways, and the concentrations of O3 and NO2, and NO at specific reaction times. The results of the theoretical model were that the reactivity of the gas mixture towards alfa-pinene and delta-3-carene was underestimated. But, the calculated concentrations of O3, NO2, and NO in the theoretical model were found to correspond to a high degree with experimental results performed under similar conditions. The possible associations between organic compounds in indoor air, building variables and the presence of sick building syndrome were studied using principal component analysis. The most complex model was able to separate 71% of the “sick” buildings from the “healthy” buildings. The most important variables that separated the “sick” buildings from the “healthy” buildings were a more frequent occurrence or a higher concentration of compounds with shorter retention times in the “sick” buildings. The outcome of this thesis could be summarised as follows; - - - -
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Oxidation of terpenes in indoor environments : A study of influencing factorsPommer, Linda January 2003 (has links)
<p>In this thesis the oxidation of monoterpenes by O3 and NO2 and factors that influenced the oxidation were studied. In the environment both ozone (O3) and nitrogen dioxide (NO2) are present as oxidising gases, which causes sampling artefacts when using Tenax TA as an adsorbent to sample organic compounds in the air. A scrubber was developed to remove O3 and NO2 prior to the sampling tube, and artefacts during sampling were minimised when using the scrubber. The main organic compounds sampled in this thesis were two monoterpenes, alfa-pinene and delta-3-carene, due to their presence in both indoor and outdoor air. The recovery of the monoterpenes through the scrubber varied between 75-97% at relative humidities of 15-75%.</p><p>The reactions of alfa-pinene and delta-3-carene with O 3, NO2 and nitric oxide (NO) at different relative humidities (RHs) and reaction times were studied in a dark reaction chamber. The experiments were planned and performed according to an experimental design were the factors influencing the reaction (O3, NO2, NO, RH and reaction times) were varied between high and low levels. In the experiments up to 13% of the monoterpenes reacted when O3, NO2, and reaction time were at high levels, and NO, and RH were at low levels. In the evaluation eight and seven factors (including both single and interaction factors) were found to influence the amount of alfa-pinene and delta-3-carene reacted, respectively. The three most influencing factors for both of the monoterpenes were the O 3 level, the reaction time, and the RH. Increased O3 level and reaction time increased the amount of monoterpene reacted, and increased RH decreased the amount reacted.</p><p>A theoretical model of the reactions occurring in the reaction chamber was created. The amount of monoterpene reacted at different initial settings of O3, NO2, and NO were calculated, as well as the influence of different reaction pathways, and the concentrations of O3 and NO2, and NO at specific reaction times. The results of the theoretical model were that the reactivity of the gas mixture towards alfa-pinene and delta-3-carene was underestimated. But, the calculated concentrations of O3, NO2, and NO in the theoretical model were found to correspond to a high degree with experimental results performed under similar conditions. The possible associations between organic compounds in indoor air, building variables and the presence of sick building syndrome were studied using principal component analysis. The most complex model was able to separate 71% of the “sick” buildings from the “healthy” buildings. The most important variables that separated the “sick” buildings from the “healthy” buildings were a more frequent occurrence or a higher concentration of compounds with shorter retention times in the “sick” buildings.</p><p>The outcome of this thesis could be summarised as follows;</p><p>-</p><p>-</p><p>-</p><p>-</p>
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Electron Transfer and Other Reactions Using Atomic Metal AnionsButson, Jeffery M. 04 February 2014 (has links)
The atomic metal anions Rb-, Cs-, Cu-, Ag- and Fe- have been generated in the gas phase and reacted with various neutral reactants in a triple quadrupole mass spectrometer. The metal anions were formed via electrospray ionization of the metal-oxalate solutions and form in gas phase between the capillary and the first quadrupole. Neutral gas phase reactants investigated include NO, NO2, SO2, C6F5OH, C6F5NH2, C6F6, E-octafluoro-butene and 1,2,3/1,2,4/1,3,5 trifluoro-benzene. When possible, CBS-4M methods were used to suggest the lowest energy products based on relative energy. Observed reactions of atomic metal anions with the aforementioned neutral species include electron transfer and dissociative electron transfer to the neutral gas phase reactants. In addition, hydrogen abstraction and fluorine abstraction forming a neutral metal hydride or fluoride as well as the formation of multiply substituted metal-oxide/fluoride anions was also observed. Metal-complex anions observed from the gas phase reactions include CuF-,CuF2-,CuO-,CuO2-, FeO-, FeO2-, FeO3-, FeF-, FeF2-, FeF3-, CsF- and CsF2-.
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Electron Transfer and Other Reactions Using Atomic Metal AnionsButson, Jeffery M. January 2014 (has links)
The atomic metal anions Rb-, Cs-, Cu-, Ag- and Fe- have been generated in the gas phase and reacted with various neutral reactants in a triple quadrupole mass spectrometer. The metal anions were formed via electrospray ionization of the metal-oxalate solutions and form in gas phase between the capillary and the first quadrupole. Neutral gas phase reactants investigated include NO, NO2, SO2, C6F5OH, C6F5NH2, C6F6, E-octafluoro-butene and 1,2,3/1,2,4/1,3,5 trifluoro-benzene. When possible, CBS-4M methods were used to suggest the lowest energy products based on relative energy. Observed reactions of atomic metal anions with the aforementioned neutral species include electron transfer and dissociative electron transfer to the neutral gas phase reactants. In addition, hydrogen abstraction and fluorine abstraction forming a neutral metal hydride or fluoride as well as the formation of multiply substituted metal-oxide/fluoride anions was also observed. Metal-complex anions observed from the gas phase reactions include CuF-,CuF2-,CuO-,CuO2-, FeO-, FeO2-, FeO3-, FeF-, FeF2-, FeF3-, CsF- and CsF2-.
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