Bibliografías temáticas / Quantification des radicaux

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Literatura académica sobre el tema "Quantification des radicaux"

Autor: Grafiati
Publicado: 25 de mayo de 2024

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Artículos de revistas sobre el tema "Quantification des radicaux"

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Schwarz-Selinger, T., V. Dose, W. Jacob y A. von Keudell. "Quantification of a radical beam source for methyl radicals". Journal of Vacuum Science & Technology A: Vacuum, Surfaces, and Films 19, n.º 1 (enero de 2001): 101–7. http://dx.doi.org/10.1116/1.1326939.

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Blakley, Richard L., Dwight D. Henry, Walter T. Morgan, William L. Clapp, Carr J. Smith y David Barr. "Quantitative Electron Paramagnetic Resonance: The Importance of Matching the Q-Factor of Standards and Samples". Applied Spectroscopy 55, n.º 10 (octubre de 2001): 1375–81. http://dx.doi.org/10.1366/0003702011953504.

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Electron paramagnetic resonance (EPR) quantification of free radicals from different samples facilitates comparison of free radical concentrations. Stable free radicals, such as 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO), in a suitable solvent (e.g., benzene) can be used as a quantification standard. Free radicals found in samples can be shorter lived than radicals in prepared standards and require stabilizing spin-trapping agents such as N-tert-butyl-α-phenylnitrone (PBN) in an appropriate solvent (e.g., benzene). Analysis in our laboratory showed that free radicals from spin-trapped samples quantified against a standard of TEMPO in benzene displayed large differences among identical samples measured on either a Micro-Now 8300, Micro-Now 8400, or Bruker EMX EPR instrument. The Bruker instrument reported that the typical TEMPO in benzene standard had a Q-factor of ∼4400 while the Q-factor of our PBN-containing samples was ∼2500. (The Q-factor is inversely proportional to the amount of dissipated microwave energy in an EPR cavity.) By placing the TEMPO standard in a PBN/benzene solvent matrix we were able to match the Q-factor of our standards and samples, resulting in each of the three EPR instruments giving the same quantified free radical yields for the samples. This result points out the importance of matching the Q-factor between samples and standards for any quantitative EPR measurement.
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Morgan, Christopher G., Mark M. Gleason y Ronald Vane. "Quantification of Contaminant Removal by Evactron Cleaning Using Quartz Crystal Thickness Monitors". Microscopy Today 15, n.º 5 (septiembre de 2007): 22–25. http://dx.doi.org/10.1017/s1551929500061198.

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Hydrocarbon (HC) contamination is a persistent problem for users of electron microscopes (EMs), often leading to image distortion and interference with nanoprobing. The Evactron De-Contaminator (D-C) has been available for HC contamination removal in EMs since 1999. The Evactron D-C uses low power radio frequency (RF) generated plasma in order to produce oxygen radicals that clean the EM. The Oxygen Radical Source (ORS) is attached to the EM chamber, and a controlled leak of oxygen containing gas such as room air is passed through the plasma in order to produce oxygen radicals. The oxygen radicals chemically react with the HCs to form volatile oxidation products such as H2O, CO and CO2. These volatile compounds are pumped out of the EM chamber.
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Cho, Eun Chul, Ju A. La, Sora Lim y Ji Eun Song. "Gold/Silver-Polymer Hybrid Nanostructures as Thermoreversible Optical Sensors and Probes for the Quantification Radical Compounds". MRS Proceedings 1802 (2015): 41–44. http://dx.doi.org/10.1557/opl.2015.833.

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ABSTRACTWe present gold (Au) and silver (Ag) nanoparticles (NPs) could be used not only for stimuli-responsive optical sensors but also for the quantification of radical compounds when these nanoparticles are suitably combined with polymeric materials. When Au NPs are assembled 2-dimensionally on the surface of hydrogel NPs which respond to temperatures, the hybrid NPs displayed thermoreversible multiple color switching. Accordingly, optical bandwidths of the hybrid NPs are reversibly changed with temperatures: with hybrid NPs assembled with 51 nm Au NPs, prominent optical signals are recorded at 900 nm at 50 °C while most of extinction signals are shown below 600 nm at room temperatures. In addition, we demonstrate the modification of Ag NPs’ surfaces (nanocubes and nanospheres) with polyelectrolytes (either positive or negative) could extend the quantifiable detection ranges of radical compounds. Through the surface modification of Ag NPs, the polyelectrolytes protect the Ag NPs by probably either retarding (forming diffusion barriers) or preventing (blocking/entrapping/scavenging) the arrival of radicals to Ag NPs or both. The roles of the polyelectrolytes are demonstrated by using radical compounds produced from tetrahydrofuran and H2O2. From the results, we could obtain calibration curves for the wide-range quantification of radical compounds.
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Goyal, Parveen Kumar, Santosh Kumar Verma y Anil Kumar Sharma. "Quantification of Total Phenolic and Flavonoid Contents, and Evaluation of Free Radical Scavenging Potential of Vernonia cinerea". Asian Pacific Journal of Health Sciences 4, n.º 3 (30 de septiembre de 2017): 279–87. http://dx.doi.org/10.21276/apjhs.2017.4.3.42.

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Peralta, E., G. Roa, J. A. Hernandez-Servin, R. Romero, P. Balderas y R. Natividad. "Hydroxyl Radicals quantification by UV spectrophotometry". Electrochimica Acta 129 (mayo de 2014): 137–41. http://dx.doi.org/10.1016/j.electacta.2014.02.047.

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Koshiishi, Ichiro, Kazunori Tsuchida, Tokuko Takajo y Makiko Komatsu. "Quantification of lipid alkyl radicals trapped with nitroxyl radical via HPLC with postcolumn thermal decomposition". Journal of Lipid Research 46, n.º 11 (16 de agosto de 2005): 2506–13. http://dx.doi.org/10.1194/jlr.d500006-jlr200.

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Hughes, H. M., I. M. George, J. C. Evans, C. C. Rowlands, G. M. Powell y C. G. Curtis. "The role of the liver in the production of free radicals during halothane anaesthesia in the rat. Quantification of N-tert-butyl-alpha-(4-nitrophenyl)nitrone (PBN)-trapped adducts in bile from halothane as compared with carbon tetrachloride". Biochemical Journal 277, n.º 3 (1 de agosto de 1991): 795–800. http://dx.doi.org/10.1042/bj2770795.

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Halothane or CCl4 was co-administered with the spin trap N-tert-butyl-alpha-(4-nitrophenyl)nitrone (PBN) to rats fitted with bile duct cannuli or to isolated perfused liver preparations. Rats maintained under halothane anaesthesia generated significant amounts of free radicals, and 5-9 nmol was excreted in bile over 1 h. No adducts were detected in urine or plasma. The hepatic origin of these free radicals was confirmed by studies on isolated perfused livers where the addition of halothane to the perfusate resulted in the biliary elimination of the same PBN-trapped radical adducts. Similarly, following CCl4 administration, the same radical species were eliminated in bile in the whole animal and the perfused liver preparation. In the perfused liver, over 3 h the total biliary elimination of radicals derived from halothane or CCl4 (administered at equimolar concentrations) was approximately the same (5-7 nmol); however, the elimination of halothane-derived radicals was more rapid over the first 1 h.
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Gardner, Jonathan M. y Steven D. Aust. "Quantification of hydroxyl radical produced during phacoemulsification". Journal of Cataract & Refractive Surgery 35, n.º 12 (diciembre de 2009): 2149–53. http://dx.doi.org/10.1016/j.jcrs.2009.06.030.

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Tanev, Mihail, Georgi Tomov y Yordanka Karakirova. "EPR Spectroscopy Investigation of Oxygen Radical Production by Methylene Blue and Indocyanine Green in Aqueous Solutions under Laser Irradiation in the Context of Antibacterial Photodynamic Therapy". Folia Medica 63, n.º 3 (30 de junio de 2021): 372–76. http://dx.doi.org/10.3897/folmed.63.e52102.

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Introduction: Antibacterial photodynamic therapy is a promising treatment modality in the anti-infective therapy of numerous oral diseases. It involves photo activation of a reactive substance (dye), thus releasing reactive oxygen species (ROS-radicals) which are highly destructive to the bacterial cell. However, thorough investigation of radical production properties of different dyes is not common in literature.Aim: The aim of this study was to investigate and evaluate oxygen radical-producing potential of two commonly used photoactive dyes in the context of antibacterial photodynamic therapy.Materials and methods: The radical-producing properties of two commonly used dyes for photodynamic therapy in oral medicine, methylene blue and indocyanine green, irradiated under laser irradiation are investigated using electron paramagnetic resonance (EPR) spectroscopy. The detection of reactive oxygen species is performed with “spin-trapping” technique.Results: The selected photoactive dyes showed promising yields of reactive oxygen species (ROS) in aqueous solutions. The comparative analysis of the results deemed methylene blue as the more productive photoactive agent.Conclusions: By employing the spin-trapping technique, this study indicates EPR-spectroscopy as a promising method of relative quantification of reactive oxygen species released by the photodynamic reaction in aqueous solutions.
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Tesis sobre el tema "Quantification des radicaux"

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Gilles, Manon. "Quantification des espèces radicalaires produites en présence de nanoparticules d’or soumises à un rayonnement ionisant". Thesis, Paris 11, 2015. http://www.theses.fr/2015PA112120/document.

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Afin d’améliorer les traitements par radiothérapie, des radiosensibilisateurs tels que les nanoparticules d’or (NPo) sont étudiés. Mais leur translation en clinique nécessite une bonne compréhension des phénomènes en jeu. Si l’effet radiosensibilisateur a bien été confirmé sur des cibles biologiques (ADN, cellules et in vivo) et si les radicaux hydroxyle ont souvent été proposés comme intermédiaires, aucune preuve claire n’a encore été apportée. Ce travail avait pour premier objectif d’élaborer un protocole de « référence » afin de quantifier les radicaux hydroxyle et les électrons produits par les NPo en interaction avec un rayonnement ionisant. Cette étude a mis en évidence des productions massives de ces deux espèces pour des NPo non-fonctionnalisées. De plus, l'étude de différents paramètres, tels que la quantité de dioxygène en solution ou le rayonnement incident, nous a conduits à proposer un nouveau mécanisme permettant de rendre compte de nos résultats. Néanmoins, l'application biologique des NPo ne peut être envisagée que si ces nano-objets sont fonctionnalisés afin de les rendre furtifs et de les adresser spécifiquement à la tumeur. Après synthèse et caractérisation poussée de différents types de NPo fonctionnalisées, nous avons comparé la production de radicaux hydroxyle avec la dégradation d’une cible biologique, l'ADN, et mis en évidence l'impact significatif de la fonctionnalisation sur l'effet radiosensibilisateur. Ainsi, cette étude apporte des informations essentielles en vue de l’optimisation de la conception des NPo les plus efficaces pour la radiosensibilisation, une première étape vers leur application radiothérapeutique
To improve radiotherapy efficiency, radiosensitizers such as gold nanoparticles (GNP) are developed. But to translate them to clinics, a good knowledge of the processes at stage is needed. GNP radiosensitizing effect was well-confirmed on biological targets (DNA, cells and in vivo) and hydroxyl radicals are often proposed to be key intermediates, but no clear evidence has been given yet. In this work, we first developed a ‘reference’ protocol to quantify hydroxyl radicals and electrons produced by GNP in their interaction with ionizing radiation. These investigations reveal a massive production of both species for non-functionalized GNP. Moreover the study of various parameters such as the concentration of dissolved dioxygen or the energy of the incident radiation leads us to propose a new mechanism on the origin of the radiosensitizing effect. Nevertheless, biological applications of GNP can only be considered if the nano-objects are functionalized to make them furtive, address them or deliver medicines to the tumor. After synthesis and characterization of different functionalized GNP, we compared hydroxyl radicals production with the damages induced on DNA and highlighted a significant impact of functionalization on the radiosensitizing effect. Finally, this work gives valuable information for the design of the most efficient GNP for radiotherapy which is a first step towards their medical application
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Eliet-Barois, Sophie. "Détection, quantification et cinétique TéraHertz de molécules d'intérêt atmosphérique". Phd thesis, Université du Littoral Côte d'Opale, 2013. http://tel.archives-ouvertes.fr/tel-00957068.

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Cette thèse évolue selon trois axes de recherche. La première partie présente des travaux de spectroscopie TéraHertz (THz) de COV réalisés à l'aide du spectromètre THz par technique de photomélange, ce dernier rendant accessible la région spectrale 0,3-3 THz à haute résolution. Ces travaux concernent l'amélioration de paramètres moléculaires du formaldéhyde (H₂CO) obtenue grâce à la mise en oeuvre d'un système de métrologie performant reposant sur l'utilisation d'un peigne de fréquence. La très haute résolution de ce spectromètre a également permis un travail de collaboration efficace avec différents laboratoires concernant la détermination de coefficients d'élargissement du chlorure de méthyle (CH₃Cl). La deuxième partie montre la possibilité de détection de radicaux légers par technique de photomélange au travers d'études concernant les radicuax hybroxyle (OH) et mercaptan (SH). La très haute résolution de notre spectromètre donne accès à leur structure hyperfine avec des précision encore inégalées dans la région 1-3 THz. Cette partie illustre également l'intérêt de notre collaboration avec la ligne AILES du synchrotron SOLEIL et démontre la grande complémentarité entre le spectromètre photo-mélange et l'interféromètre couplée au rayonnement synchrotron. La dernière partie présente l'initiation au sein du groupe THz d'une étude cinétique effectuée grâce à une chaîne par multiplication de fréquence. Cette étude concerne concerne la photolyse de H₂CO. S'ajoute à ceci une étude visant à caractériser le rayonnement THz en présence d'aérosols de chlorure de sodium hydratés.
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Ranchon, Isabelle. "La photodegenerescence retinienne : quantification d'un modele et place des radicaux libres dans le processus degeneratif (doctorat : biophysique sensorielle)". Clermont-Ferrand 1, 1999. http://www.theses.fr/1999CLF1PP01.

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Masselot, David. "Identification et quantification des radicaux libres par spectrométrie de masse : application à l'étude et à la diminution des radicaux libres contenus dans la fumée de cigarette". Lille 1, 2004. http://www.theses.fr/2004LIL10069.

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Les radicaux libres sont capables de réagir avec pratiquement toutes les familles de molécules présentes dans les systèmes biologiques. Ainsi les radicaux libres réagissent en particulier sur l'ADN, induisant des mutations qui conduisent au développement de cancer. De même les radicaux libres réagissent avec les lipides, produisant des phénomènes inflammatoires qui peuvent entraîner le développement de maladies cardiovasculaires. La Résonance Paramagnétique Électronique est la technique classique pour l'identification et la quantification des radicaux libres. Pour la plupart des radicaux en solution une étape de piégeage du radical pour former une espèce radicalaire à longue durée de vie est indispensable. Les milieux réactionnels sièges de réaction d'oxydoréduction conduisent à une transformation de ces adduits en espèces non radicalaires qui ne sont plus détectables par Résonance paramagnétique Électronique. De plus l'identification des radicaux est difficile dans le cas de mélange complexes
Nous avons développé une nouvelle méthode de détection et de quantification des radicaux libres basée sur la spectrométrie de masse en utilisant l'ionisation par électronébulisation. Nous avons tout d'abord testé les principales familles de piégeurs de radicaux en spectrométrie de masse. Nous en avons optimisé les conditions d'analyse par spectrométrie de masse pour une nitrone, la 2,2,5-triméthyl-3-phényl-3,4-dihydro-2H-pyrrole-l-oxyde (TMPO), spécifique des radicaux centrés sur les hétéroélements et pour un nitroxyde, le 3-amino-2,2,5,5-tetraméthyl-pyrrolidinyloxy (AMP), spécifique des radicaux C-centrés. Nous avons constitué une bibliothèque MS/MS des différents types de radicaux libres permettant leur identification dans des mélanges complexes. Nous avons ensuite appliqué cette méthodologie pour identifier et quantifier les radicaux libres présents dans les fumées de cigarette. La quantité globale de radicaux est de l'ordre de 2. 10+17 radicaux par cigarette fumée en accord avec les études antérieures. Nous avons identifié et quantifié de nombreux radicaux originaux dans la fumée de cigarette comme les radicaux hydroxyle (OH), cyanogène (CN) et méthyle (CH3). Cette étude a également permis de déboucher sur des recherches d'optimisation de filtres permettant la diminution de la teneur en substance radicalaire de la fumée de cigarette. Nos résultats ont montré de plus que les différentes familles de radicaux présentes dans la fumée de cigarette sont éliminés avec des efficacités variables
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Nabokoff, Pierre. "Synthèses de précurseurs organiques de radicaux hétéroatomiques pour la préparation de matériaux hybrides". Electronic Thesis or Diss., Aix-Marseille, 2020. http://theses.univ-amu.fr.lama.univ-amu.fr/201218_NABOKOFF_575sxytx526xlluw827l449jumhkc_TH.pdf.

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Cette étude a pour but d’explorer l’influence du nanoconfinement sur le comportement de substrats organiques incorporés dans des silices mésoporeuses. Ces travaux s’articulent en deux volets. Le premier est une étude sur l’efficacité de la réaction de fragmentation par voie photochimique ou thermique d’alcoxyamines confinées. Par comparaison avec une étude réalisée en solution, des mesures effectuées par spectroscopie RPE quantitative ont permis de montrer que l’efficacité de cette rupture n’est pas altérée par l’incorporation des précurseurs organiques dans une matrice de silice. Dans un second temps des matériaux hybrides organiques-inorganiques fonctionnalisés par des précurseurs diazèniques ont été synthétisés. Ces derniers sont capables, sous irradiation à 360 nm, de former des radicaux hétéroatomiques qui sont transitoires en solution mais persistants dans la silice. Différentes structures ont été synthétisées, notamment des matériaux fonctionnalisés par une paire de radicaux de nature différente, i.e. un radical aryloxyle disposé face à un radical arylsulfanyle. Des études RPE en onde continue et pulsée ont permis de mettre en évidence la grande durée de vie de ces espèces paramagnétiques confinées et de mesurer leurs temps de relaxation
The aim of this work was to investigate the influence of the nanocofinement on the behaviour of organic substrates embedded in mesoporous silicas. This research hinged on two parts. The first study focused on the efficiency of the fragmentation reaction of confined alkoxyamines, under thermal or photochemical activation. Thanks to the comparison with the very same reactions in solution, the quantitative EPR measurements showed that the confinement of organic precursors had no effect on the efficiency of these reactions. Secondly, organic-inorganic hybrid materials were synthesized. These mesoporous silicas were functionalized with diazene radical precursors. Upon 360 nm irradiation, they generated heteroatomic radicals. Different materials were prepared, including one which enabled to form a face-to-face pair of different radicals, i.e. an aryloxyl radical in front of an arylsulfanyl radical. Studies carried out by continuous and pulsed wave EPR enabled to highlight the high stability of these confined paramagnetic species and to measure their relaxation times
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Poupon, Julien. "Quantification des voies métaboliques de l'éthanol par le cytochrome P450 2E1 : rôles respectifs de l'acétaldéhyde et des radicaux libres hydroxyéthyles dans l'hépatotoxicité de l'éthanol". Brest, 2003. http://www.theses.fr/2003BRES3108.

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L'hépatotoxicité alcoolique met en jeu les produits du métabolisme de l'éthanol par le cytochrome P450 2E1 (CYP2E1) tels que l'acétaldéhyde (oxydation bi-électronique) et les radicaux hydroxyéthyles (HER) (oxydation mono-électronique). Le CYP2E1 est le principal site d'oxydation micromal de l'éthanol (84% chez le rat, 30% chez l'Homme). L'oxydation produit de l'acétaldéhyde et des HER dans le rapport 9/1. La voie mono-électronique représente 5 à 7 %. L'incubation de guanine avec des HER produits in situ entraîne la formation d'adduits HER-guanine (HEG) (12% de la guanine). Les adduits HEG n'ont pas pu être détectés au niveau de l'Adn de patients alcooliques, d'hépatocytes en culture traotés à l'alcool, ni d'ADN incubé avec des microsomes et de l'alcool. L'étude de l'alkylation des protéines microsomales montre que les adduits HER se forment principalement avec le CYP2E1. Néanmoins, la formation d'HER-CYP2E1 n'affecte pas son activité catalytique sous des conditions normales
Hepatotoxicity of alcoholic intoxication brings into play the products resulting from the metabolism of ethanol by the cytochrome P4502E1 (CYP2E1): acetaldehyde (two-electron oxidation), and hydroxyethyl radicals (HER) (one electron-oxidation). This products can form adducts with surrounding molecules. CYP2E1 is the principal site of oxidation microsomal of ethanol (84% in the rat, only 30% in the Man ). Ethanol oxidation leads to the formation of acetaldehyde and HER in the 9/1 ratio. The contribution of the mono-electronics pathway, revealed by spin-trapping method of HER, accounts for 5 to 7 %. Incubation of guanine with HER formed in situ results in HER-guanine adducts (HEG) (12% of incubated guanine). However, HEG adducts could not be detected either in DNA from several biological materiels. Alkylation of the microsomals proteins shows that adduits HER are formed mainly with the CYP2E1. The formation of HER-CYP2E1 does not affect the catalytic activity under normal conditions
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Harish, Harish [Verfasser] y Hendrik [Akademischer Betreuer] Zipse. "Structure and stability of radicals and quantification of electrophilic reactivity / Harish Harish ; Betreuer: Hendrik Zipse". München : Universitätsbibliothek der Ludwig-Maximilians-Universität, 2019. http://d-nb.info/1178324176/34.

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Venegas, Julianna Marie Cebollero. "Photochemistry studies in snow and ice quantification of hydroxyl radicals and degradation of persistent organic pollutants /". Click here for download, 2009. http://proquest.umi.com/pqdweb?did=1827193651&sid=1&Fmt=2&clientId=3260&RQT=309&VName=PQD.

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Nascimento, Roberto Jefferson Bezerra do. "Desenvolvimento de método de quantificação dos constituintes fenólicos e ação anti-radical de vinhos tintos nacionais e importados". Universidade Federal da Paraí­ba, 2010. http://tede.biblioteca.ufpb.br:8080/handle/tede/6694.

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Resveratrol (cis and trans) and quercetin are important components in ensuring the quality of wine because of the diversity of biological activities that they have. Studies quantifying these constituents in Brazilian wines are rarely reported in the literature, especially in wines from the Vale Submédio do São Francisco. The objectives of this work were to develop and validate a quantification method for cis-resveratrol, trans-resveratrol, total resveratrol and quercetin by HPLC-UV in red wines, to evaluate and correlate the levels of total phenolics by Folin-Ciocalteu method with the anti-radical activity determined usingm the DPPH radical method and to determine the potential for classification of wines from their chromatographic profiles. In the study 45 samples of red wines were analysed. From these, 30 samples were from Brazilian wines:15 of the Vale Submédio do São Francisco, 11 of Serra Gaucha and 4 of Campanha Gaucha. There were 15 samples of imported wines: 5 from Argentina, 5 from Chile and 5 from French. The method developed for quantification of resveratrol (cis and trans) and quercetin was validated andused in the quantification. The results showed that Brazilian wines have about nine times more cis-resveratrol than trans-resveratrol and this relationship is even more pronounced in the Vale do São Francisco, with about 17 times more cis-resveratrol than trans-resveratrol in red wines from this region. The French wines presented quercetin in an amount above the rest of the wine samples. It was also observed that the wines from the Vale do São Francisco had higher levels of total resveratrol, significantly higher than imported wines, with p=0.0381. The total phenolics content was markedly higher in the wines from the Vale do São Francisco in relation to wines from the South, with p=0.001. The study of anti-radical activity against the DPPH radical showed that all wines are active, with EC50<130 μg/mL. In the study of the chromatographic profiles of the wines four distinct groupings among the wines were found, with 87% of the samples from the Vale do São Francisco, 80% of Chileans wines, 60% of the Serra Gaucha wines and 55% of French wines. Taken toghether the results show that Brazilian wines presented high level of phenolics, especially the wines from Vale do Submédio do São Francisco. This is translated into high levels of bioactive substances such as resveratrol (cis and trans) and quercetin, as well the high antioxidant activity. The high intensity of solar light in Brazil, mainly in the Vale do São Francisco, may have been the main factor contributing to the high content of these constituents, thus contributing to the high degree of grouping shown by the wines of this region using multivariate analysis.
O resveratrol (cis e trans) e quercetina são componentes de grande importância na garantia da qualidade do vinho, devido à diversidade de atividades biológicas que eles possuem. Estudos de quantificação destes constituintes em vinhos brasileiros são pouco relatados na literatura, especialmente nos vinhos do Vale Submédio do São Francisco. Os objetivos deste trabalho foram desenvolver e validar um método de quantificação do cis-resveratrol, trans-resveratrol, resveratrol total e quercetina por CLAE-UV/Vis em vinhos tintos, avaliar e correlacionar os teores de fenólicos totais pelo método de Folin-Ciocalteu com a atividade anti-radicalar, frente ao radical DPPH e determinar o potencial de classificação dos vinhos a partir dos perfis cromatográficos. Para execução do trabalho foram analisadas 45 amostras de vinhos tintos, sendo 30 brasileiros das regiões do Vale Submédio do São Francisco (15), Serra Gaúcha (11) e Campanha Gaúcha (4), e 15 importados: argentinos (5), chilenos (5) e franceses (5). O método desenvolvido para quantificação de resveratrol isômeros (cis e trans) e quercetina apresentou dados e características suficientemente bons para ser validado e utilizado no processo de quantificação. Os resultados obtidos demonstraram que os vinhos brasileiros possuem cerca de 9 vezes mais cis-resveratrol que trans-resveratrol, esta relação é ainda mais pronunciada na região do Vale Submédio do São Francisco, sendo cerca de 17 vezes mais cis do que trans. Os vinhos franceses apresentaram quercetina em quantidade superior ao restante dos conjuntos amostrais de vinhos. Foi observado também que os vinhos do Vale Submédio do São Francisco possuem teores de resveratrol total, significativamente superiores aos vinhos importados, com p=0,0381. O teor de fenólicos totais foi marcadamente superior nos vinhos do Vale Submédio do São Francisco em relação aos vinhos da região Sul, com p=0,001. O estudo de atividade anti-radicalar frente ao radical DPPH demonstrou que todos os vinhos são ativos, com CE50 <130 μg/mL. No estudo do perfil cromatográfico dos vinhos foram determinados quatro agrupamentos distintos, sendo 87 % entre os vinhos do Vale Submédio do São Francisco, 80 % entre os chilenos, 60 % entre os da Serra Gaúcha e 55 % entre os vinhos franceses. Os estudos realizados com os vinhos revelaram resultados que posicionam os vinhos brasileiros, especialmente os vinhos da região do Vale Submédio do São Francisco, em um elevado patamar em termos de qualidade. Isto é corroborado pelos elevados teores de substâncias bioativas tais como o resveratrol (isômeros cis e trans) e quercetina, bem como o elevado teor de fenólicos totais e alta atividade anti-radicalar. A alta intensidade de insolação no Brasil, principalmente na região do Vale Submédio do São Francisco, pode ter sido o principal fator a contribuir para elevação do teor destes constituintes, contribuindo, desta forma, para um elevado grau de agrupamento dos vinhos desta região por análise multivariada.
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Cheng, Chia-Chien y 鄭佳倩. "Quantification of Hydroxyl Radicals in Photocatalytic Reactions by a Trapper/Fluoresce Technique". Thesis, 2007. http://ndltd.ncl.edu.tw/handle/34943760726039767827.

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碩士
國立高雄第一科技大學
環境與安全衛生工程所
95
The study employs dimethyl sulfoxide (DMSO) as a radical capture for quantifying formation concentration of hydroxyl radicals (·OH) in liquid-phase TiO2-photocatalytic reaction systems. In this study, a trapper/fluoresce technique has been developed to monitor formation concentration of formaldehyde which is the major reaction intermediate from reacting DMSO with hydroxyl radicals. The initial formation rate of formaldehyde is applied to calculate yield rate of the hydroxyl radicals formed onTiO2 surfaces. Several affecting factors including solution pH level, TiO2 dosage, irradiated light intensity and different wavelength light sources have been tested to investigate the capability of applying the developed technique for determining photocatalyst photocatalytic activities in various operation conditions. Experimental results indicate that DMSO concentration should be higher than 4 mM for covering most part of active sites on TiO2 particles while TiO2 concentration equal to 0.01 g/L. Otherwise, underestimation of ·OH formation concentration will be observed. The results also show hydroxyl radicals concentration increases with pH level due to increasing reactions between hydroxyl ions (OH-) with electron holes. More formation of hydroxyl radicals are detected in higher illumination light intensity, too. For the effect of TiO2 dosage concentration on the radical formation, it is observed that the overall radical yield rate increases withTiO2 concentration initially and then approaches a flat maximal level as TiO2 concentration above 200 mg/L. But the radical yield rate is declining with TiO2 concentration if the rate is expressed by unit gram of TiO2, which results from receiving less irradiated light intensity by each TiO2 particle because TiO2 particle scatters each other in high-concentration conditions. Besides, the experimental results indicate a low yield rate of hydroxyl radicals by using 446-nm light sources. The radical yield rate by using 256-nm lamps is about 2.5 times higher than by using 365-nm lamps. Finally, according to the achieved relationships among hydroxyl radical yield rates and the experimental parameters, a semi-empirical model for predicting formation rate of hydroxyl radicals is proposed in this study based on the variables including proton concentration, TiO2 concentration and irradiated light intensity. The prediction model demonstrates well correlations between radical concentrations and photocatalytic reaction rates assisted by TiO2, which not only shows the developed radical measurement technique being a good indicator representing photocatalytic activities of photocatalysts, but also indicates the formation of hydroxyl radical is the key reaction mechanism for fast degradation of organic compounds.
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Libros sobre el tema "Quantification des radicaux"

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Bentley, Michael. British Historical Writing. Oxford University Press, 2018. http://dx.doi.org/10.1093/oso/9780199225996.003.0015.

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This chapter studies British historical writing, tracing its transformations from the end of the war—when, arguably, much of the late nineteenth-century empiricist agenda was still intact, and political history continued to dominate—through signal events such as the founding of a new journal of radical historiography called Past and Present (1952), to the advent of neoconservatism in the 1980s, the puffing up and eventual bursting of the bubble of Franco-American-style quantification, and the advent of the cultural turn. Intertwined in the narratives of structural evolution, as well as generational narratives, one might see another in the growing presence of technology as a force impelling historical method and providing new ways of disseminating research. By 1995, many of Britain’s most successful historians defined themselves as ‘public intellectuals’ or tele-dons commanding a wide audience in ways that no one could have dreamed of in 1945.
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Slavin, Tanya. Verb stem formation and event composition in Oji-Cree. Oxford University Press, 2017. http://dx.doi.org/10.1093/oso/9780198778264.003.0012.

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This chapter investigates the structure of the verb stem in Oji-Cree, a dialect of the Algonquian language Ojibwe. It argues that a stem constitutes an independent semantic domain that corresponds to an event. This conception of stems explains why certain roots, called weak roots, must be preceded by modifiers, thereby satisfying a so-called left-edge requirement, while other roots, called strong roots, have no such requirement. Weak roots are semantically deficient and the obligatory pre-radical modifier is necessary to create a complete event. In contrast, an (optional) modifier before a strong root has scope over a complete event. The difference is illustrated by the morpheme /caaki/ ‘all’. When it combines stem-internally, its scope is restricted to internal arguments. However, when it combines stem-externally, it can have a quantificational reading with scope over an external argument. The semantic difference between stem-internal and stem-external composition is also correlated with some phonological differences.
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Capítulos de libros sobre el tema "Quantification des radicaux"

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Bell, David M., Manuela Cirtog, Jean-François Doussin, Hendrik Fuchs, Jan Illmann, Amalia Muñoz, Iulia Patroescu-Klotz, Bénédicte Picquet-Varrault, Mila Ródenas y Harald Saathoff. "Preparation of Experiments: Addition and In Situ Production of Trace Gases and Oxidants in the Gas Phase". En A Practical Guide to Atmospheric Simulation Chambers, 129–61. Cham: Springer International Publishing, 2023. http://dx.doi.org/10.1007/978-3-031-22277-1_4.

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AbstractPreparation of the air mixture used in chamber experiments requires typically the injection of trace gases into a bath gas. In this chapter, recommendations and standard protocols are given to achieve quantitative injections of gaseous, liquid or solid species. Various methods to produce ozone, nitrate radicals and hydroxyl radicals are discussed. Short-lived oxidants need to be produced during the experiment inside the chamber from pre-cursor species. Because highly reactive oxidants like hydroxyl radicals are challenging to detect an alternative method for the quantification of radical concentrations using trace molecules is described.
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Grintzalis, Konstantinos, Ioannis Papapostolou y Christos Georgiou. "Protocol for the In Vivo Quantification of Superoxide Radical in Fungi". En Laboratory Protocols in Fungal Biology, 259–64. New York, NY: Springer New York, 2012. http://dx.doi.org/10.1007/978-1-4614-2356-0_20.

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Samuel, Boris. "The Shifting Legitimacies of Price Measurements: Official Statistics and the Quantification of Pwofitasyon in the 2009 Social Struggle in Guadeloupe". En The New Politics of Numbers, 337–77. Cham: Springer International Publishing, 2021. http://dx.doi.org/10.1007/978-3-030-78201-6_11.

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AbstractIn 2009, Guadeloupe experienced a historic 44 day-long strike against the high cost of living. The union-led collective (LKP) leading the strike used calculations and figures as a weapon to prove that players holding dominant market positions captured undue profits (“pwofitasyon”). Also, official price indexes were subjected to radical political criticism by the LKP actors. Yet, by using averages, these calculations could not account for the existence of individual abusive prices. The “statactivistic” momentum resulted in a shift of the legitimate price measurement methods. Calculation was, however, also the collective’s Achilles heel. LKP members’ use of numbers established only a temporary favourable balance of power in the negotiations. It was not enough for them to compete with the state’s calculative skills on an equal basis.
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Mari, Luca, Mark Wilson y Andrew Maul. "Philosophical Perspectives on Measurement". En Springer Series in Measurement Science and Technology, 81–121. Cham: Springer International Publishing, 2023. http://dx.doi.org/10.1007/978-3-031-22448-5_4.

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AbstractThis chapter aims to present a brief conceptual history of philosophical thinking about measurement, concentrating in particular on the issues of objectivity and subjectivity, realism and nonrealism, and the role of models in measurement, as well as a discussion of how these philosophical issues have shaped thinking and discourse about measurement in both the human and physical sciences. First, three perspectives on measurement and its epistemic status are discussed, grouped as (a) naive realism, (b) operationalism, and (c) representationalism. Following this, we discuss how these perspectives have informed thinking about the concept of validity in the human sciences, and how they have influenced the way in which measurement is characterized in different contexts as being dependent on empirical and/or mathematical constraints. We then attempt to synthesize these perspectives and propose a version of model-dependent realism which maintains some of the elements of each of these perspectives and at the same time rejects their most radical aspects, by acknowledging the fundamental role of models in measurement but also emphasizing that models are always models of something: the empirical components of measurement are designed and operated to guarantee that, via such models, measurement results convey information on the intended property. The analysis also provides a simple explanation of two of the most critical stereotypes that still affect measurement science: the hypotheses that (1) measurement is quantification, which hides the relevance of the empirical component of the process, and that (2) measurement is only a process of transmission and presentation of preexisting information, usually intended as the “true value” of the measurand, which instead neglects the role of models in the process.
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Povinelli, Elizabeth A. "Variations of Bodies in Motion and Relation". En Porous Becomings, 117–33. Duke University Press, 2024. http://dx.doi.org/10.1215/9781478059318-007.

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This chapter builds on Elizabeth Povinelli’s reflections on how philosophies and anthropologies of radical potentiality—scholarship that posits a political or social otherwise emerges in moments of extreme social indetermination and of radical threshold experiences—fail to differentiate between lives lived as the object of colonial racism and those lived as its beneficiaries. This chapter reflects on how one might understand the social and political stakes of Serres’s attempt to find a universal ground for the variations of the body by putting Serres’s writings in conversation with those of Édouard Glissant. It asks what are the political stakes of theories of radical potentiality that are anchored in the exhausted relationship between the general and specific, the ontologically given and the socially distributed, universal quantification (All bodies are x, All beings…, All human beings…, All social relations…) and existential quantification (for some…).
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Williams, J. Robert G. "Radical Interpretation and the Logical Form of Thoughts". En The Metaphysics of Representation, 36–58. Oxford University Press, 2020. http://dx.doi.org/10.1093/oso/9780198850205.003.0003.

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This chapter is one of three that draws out the consequences of Radical Interpretation for how concepts represent the world. The focus in this chapter is on logical concepts: conjunction, negation, and universal generalization. This connects Radical Interpretation as a foundational theory of mental content to inferentialism, where commitment to certain kinds of rules of inference or coherence is cited to explain why our connectives mean what they do. Radical Interpretation, together with auxiliary assumptions about cognitive architecture and epistemology, predicts these patterns. One of the upshots is an explanation of how quantification over absolutely everything is possible, rebutting long-standing skolemite underdetermination puzzles.
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Esmark, Anders. "Technocratic Calculation: Economy, Evidence and Experiments". En The New Technocracy, 173–202. Policy Press, 2020. http://dx.doi.org/10.1332/policypress/9781529200874.003.0007.

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The chapter takes up the technocratic preoccupation with quantification, measurement and scientific politics. While this is a consistent feature of technocratic governance, the proliferation of performance management, accountability and evaluation systems, evidence-based policy and experimental learning also reflect a new commitment to radical incrementalism and a ‘what works’ approach, which is significantly different from earlier and industrial technocracy. The chapter illustrates the implications of this development in the cases of experimental EU governance and nudging interventions.
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Simmons, Katrina, Joshua S. Martin, Inna Shcherbakova y Alain Laederach. "Rapid Quantification and Analysis of Kinetic •OH Radical Footprinting Data Using SAFA". En Methods in Enzymology, 47–66. Elsevier, 2009. http://dx.doi.org/10.1016/s0076-6879(09)68003-4.

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Sabanna Patil, Kalpana y Raju Ratan Wadekar. "Lipid Peroxidation: A Signaling Mechanism in Diagnosis of Diseases". En Lipid Peroxidation [Working Title]. IntechOpen, 2021. http://dx.doi.org/10.5772/intechopen.99706.

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Quantification of reactive oxygen species, is perplexing either in vivo or in vitro due to their short half-lives. Consequently, to define the magnitude of oxidative stress, the more stable oxidation products can be measured in biological samples. The oxidative stress leads to the lipid peroxidation that involves the initiation, termination and propagation of lipid radicals, wherein, the process involves the oxygen uptake, rearrangement of the double bonds in unsaturated lipids, that leads to polyunsaturated fatty acid deterioration. Subsequently, the toxic signaling end products are considered as biomarkers of free radicals that act both as signaling molecules and as cytotoxic products cause covalent alteration of lipid peroxidation products. The use of validated signaling mechanism (s) of Lipid peroxidation and products derived thereof exhibits its use clinical practice and basic clinical research as well as in clinical practice has become common place, and their presence as endpoints in clinical trials is now broadly accepted. This knowledge can be used to diagnose disease earlier, or to prevent it before it starts. The signaling markers can be used to excel the effectiveness of the prevailing medicines and to improve the new medicines.
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Blome-Tillmann, Michael. "Semantic Implementations". En The Semantics of Knowledge Attributions, 21–45. Oxford University Press, 2022. http://dx.doi.org/10.1093/oso/9780198716303.003.0002.

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This chapter investigates possible semantic implementations of epistemic contextualism (EC). To begin with, the chapter introduces Kaplan’s distinction between character and content and uses this distinction to illustrate the need for a more detailed semantic account of the context-sensitivity of ‘knowledge’-attributions. Views discussed are fancy contextualism and classical contextualism, which is analysed further into indexicalism and radical contextualism. Indexicalism is then shown to be the version of EC discussed most widely in the literature. Different versions of indexicalism are distinguished—namely, strict indexicalism and so-called hidden variables accounts (scalar indexicalism, quantificational indexicalism, and contrastivism). Section 2.5 concludes the chapter by providing a diagram representing the most important semantic implementations of EC and their interrelations.
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Actas de conferencias sobre el tema "Quantification des radicaux"

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Okada, Kiyotaka, Kazuki Oishi, Shintaro Kodama, Douyan Wang y Takao Namihira. "Quantification of OH radicals generated by nanosecond pulsed discharge plasma". En 2019 IEEE Pulsed Power & Plasma Science (PPPS). IEEE, 2019. http://dx.doi.org/10.1109/ppps34859.2019.9009980.

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Lupaescu, Ancuta-Veronica, Nicoleta Flutur, Brindusa-Alina Petre, Monica Iavorschi y Florin Ursachi. "ENHANCING THE ANTIOXIDANT ACTIVITY OF CHAMOMILE: EXPLORING THE IMPACT OF ULTRASOUND ON PROTEIN EXTRACTION". En 23rd SGEM International Multidisciplinary Scientific GeoConference 2023. STEF92 Technology, 2023. http://dx.doi.org/10.5593/sgem2023v/6.2/s25.20.

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Chamomile flower, a well-known medicinal plant, possesses significant antioxidant properties attributed to its diverse array of bioactive compounds, including antioxidant proteins. These proteins are vital in combating oxidative stress and neutralizing harmful free radicals. To fully harness the antioxidant potential of chamomile, it is imperative to optimize the extraction methods. This study evaluates the effectiveness of nonconventional mechanical extraction methods using ultrasound to extract antioxidant compounds from chamomile, comparing it with a traditional agitation-based technique. The extracts obtained using green solvents such as basic aqueous solutions or phosphate-buffered saline (PBS) showed that while the ultrasound extraction requires a shorted extraction time compared to traditional methods, it yields a more active extract in terms of antioxidant activity. These active constituent-rich extracts were then subjected to thorough characterization and quantification using advanced analytical techniques, such as gel electrophoresis, mass spectrometry, UV-vis, and FTIR spectroscopy. Finally, the antioxidant capacity of the aqueous extract was determined using the DPPH free radical method and the FRAP assay.
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Shiraki, Daichi y Nozomi Takeuchi. "Accurate quantification of hydroxyl radicals produced by plasma using disodium terephthalate solution". En 2016 IEEE International Conference on Plasma Science (ICOPS). IEEE, 2016. http://dx.doi.org/10.1109/plasma.2016.7534385.

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Lohrmann, Martin, Horst Bu¨chner, Nikolaos Zarzalis y Werner Krebs. "Flame Transfer Function Characteristics of Swirl Flames for Gas Turbine Applications". En ASME Turbo Expo 2003, collocated with the 2003 International Joint Power Generation Conference. ASMEDC, 2003. http://dx.doi.org/10.1115/gt2003-38113.

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For the suppression or reduction of self-sustained combustion instabilities, modifications of the burner outlet conditions, that strongly influence the dynamic flame response, seem to be the most promising way. Therefore, to derive a detailed physical understanding of the feedback mechanisms the dynamic flame response characteristics, quantified by flame transfer functions, are required in dependence of flame type and operation conditions of the combustor. In the present paper measurements of flame transfer functions of an industrial, full-scale prototype gas turbine burner are discussed. For the detection of periodically-unsteady OH radical radiation (response of the flame) two different UV detection systems were compared. Because the concentration of electronically-excited OH radicals in the reaction zone and therefore, of the measured UV radiation intensity, is strongly depending on volumetric reaction density and local flame temperatures, the UV radiation intensity commonly used for the quantification of the heat release can be misinterpreted. Hence, two different concepts of fuel gas/air mixture formation have been realized in the experiments to separate and to physically interpret the influence of the mixture formation and its quality on the UV radiation intensity of the determined flame transfer functions. The derived understanding of the complex interactions of mixture mass flow oscillations, fluctuations of the mixture composition and the periodic combustion of ring vortices at a full-scale burner is an essential requirement for the interpretation of flame dynamics based on measurements of the UV radiation intensity.
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Wu, Xiaolin, Joshua Tay, Chuan Keng Goh, Cheryl Chan, Yie Hou Lee, Stacy L. Springs, De Yun Wang, Kwok Seng Loh, Timothy K. Lu y Hanry Yu. "A Rapid DIgital Crispr Approach (RADICA) for the detection and absolute quantification of nucleic acids". En Frontiers in Biological Detection: From Nanosensors to Systems XIV, editado por Benjamin L. Miller, Sharon M. Weiss, Amos Danielli, Ramesh Raghavachari y Mikhail Y. Berezin. SPIE, 2022. http://dx.doi.org/10.1117/12.2614195.

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Grönstedt, Tomas, Mohammad Irannezhad, Xu Lei, Oskar Thulin y Anders Lundbladh. "First and Second Law Analysis of Future Aircraft Engines". En ASME Turbo Expo 2013: Turbine Technical Conference and Exposition. American Society of Mechanical Engineers, 2013. http://dx.doi.org/10.1115/gt2013-95516.

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An optimal baseline turbofan cycle designed for a performance level expected to be available around year 2050 is established. Detailed performance data are given in take-off, top of climb and cruise to support the analysis. Losses are analyzed based on a combined use of the first and second law of thermodynamics, to establish a basis for discussion on future radical engine concepts and to quantify loss levels of very high performance engines. In the light of the performance of the future baseline engine, three radical cycles designed to reduce the observed major loss sources are introduced. The combined use of a first and second law analysis of an open rotor engine, an intercooled recuperated engine and an engine working with a pulse detonation combustion core is presented. In the past, virtually no attention has been paid to the systematic quantification of the irreversibility rates of such radical concepts. Previous research on this topic has concentrated on the analysis of the turbojet and the turbofan engine. In the framework developed, the irreversibility rates are quantified through the calculation of the exergy destruction per unit time. A striking strength of the analysis is that it establishes a common currency for comparing losses originating from very different physical sources of irreversibility. This substantially reduces the complexity of analyzing and comparing losses in aero engines. In particular, the analysis sheds new light on how the intercooled recuperated engine establishes its performance benefits.
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March, Martin, Julian Renner y Thomas Sattelmayer. "Acoustic and Optical Investigations of the Flame Dynamics of Rich and Lean Kerosene Flames in the Primary Zone of an Air-Staged Combustion Test-Rig". En ASME Turbo Expo 2023: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2023. http://dx.doi.org/10.1115/gt2023-103105.

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Abstract In this study the thermoacoustic behavior of non-premixed kerosene flames from rich to lean combustion conditions is investigated. Flame-transfer-functions measured purely acoustically are compared with results based on flame chemiluminescence. OH*, CH*, C2* and CO2* were selected as potential measures for representing steady and fluctuating heat release when burning non-premixed kerosene. In addition, their ability for the quantification of equivalence ratio fluctuations will be highlighted. The measurements were performed in the primary zone of an atmospheric rich-quench-lean (RQL) combustion test-rig. The new experimental approach allows a characterization of the primary zone independent of the secondary zone. Rich and lean operating points were analyzed by fueling an aero-engine prototype injector with and without acoustic excitation. To improve the quality of the acoustic wavefield reconstruction a thermocouple correction method was implemented. The flame dynamics determined with the multimicrophone method exhibit a frequency and equivalence ratio depending effect for rich combustion conditions. The results for the steady behavior of the chosen radicals by altering equivalence ratio and thermal power indicate proportionality of the chemiluminescence to thermal power. Furthermore, the CH*/C2* ratio is found to be a promising indicator for the global equivalence ratio in the combustion chamber. The flame-transfer-functions based on chemiluminescence show a good qualitative agreement with the multimicrophone method. Based on the experimental findings a calibration curve for the different radicals to obtain quantitatively correct flame-transfer-functions from chemiluminescence is presented.
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Durocher, Antoine, Philippe Versailles, Gilles Bourque y Jeffrey M. Bergthorson. "Uncertainty Quantification of NOx Emissions Induced Through the Prompt Route in Premixed Alkane Flames". En ASME Turbo Expo 2018: Turbomachinery Technical Conference and Exposition. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/gt2018-75579.

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Increasingly stringent regulations on emissions in the gas turbine industry require novel designs to minimize the environmental impact of oxides of nitrogen (NOx). The development of advanced low-NOx technologies depends on accurate and reliable thermochemical mechanisms to achieve emissions targets. However, current combustion models have high levels of uncertainty in kinetic rates that, when propagated through calculations, yield significant variations in predictions. A recent study identified and optimized nine elementary reactions involved in CH formation to accurately capture its concentration and improve prompt-NO predictions. The current work quantifies the uncertainty on peak CH concentration and NOx emissions generated by these nine reaction rates only, when propagated through the San Diego mechanism. Various non-intrusive spectral methods are used to study atmospheric alkane-air flames. 1st- and 2nd-order total-order expansions and tensor-product expansions are compared against a reference Monte Carlo analysis to assess the ability of the different techniques to accurately quantify the effect of uncertainties on the quantities of interest. Sparse grids, subsets of the full tensor-product expansion, are shown to retain the advantages of tensor formulation compared to total-order expansions while requiring significantly fewer collocation points to develop a surrogate model. The high resolution per dimension can capture complex probability distributions witnessed in radical species concentrations. The uncertainty analysis of lean to rich flames demonstrated a high variability in NOx predictions reaching up to 400 % of nominal predictions. Wider concentration intervals were observed in rich conditions where prompt-NOx is the dominant contributor to emissions. The high variability and scale of uncertainty in NOx emissions originating from these nine elementary reactions demonstrate the need for future experiments and data assimilation to constrain current models to accurately capture CH for robust NOx emissions predictions.
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Kwiecien, Janusz. "Accuracy Test of Laser Tracker under Condition of Air Turbulence". En Environmental Engineering. VGTU Technika, 2017. http://dx.doi.org/10.3846/enviro.2017.211.

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Laser tracking for interior industrial metrology is discussed. In this work, the effects of air turbulence on the angle of laser wave propagation is analyzed in the absence of the effects associated with other meteorological parameters (pressure, humidity) and particulate pollutants (dust, smoke). This analysis establishes the effectiveness of laser tracking under turbulent air conditions and quantification of deviations in the angular and linear accuracy from those provided by the manufacturer. An experimental setup and associated measurement method to determine the turbulence structure coefficient are described. It was found that turbulent air conditions resulted in a radical decrease in measurement accuracy. The reduction in accuracy was evidenced by a decrease in power and an increase in standard deviation of the laser beam, as well as a decline in the angle and distance measurement precision. The experimental measurements show a high correlation to predicted values.
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Katzy, Peter, Lorenz R. Boeck, Josef Hasslberger y Thomas Sattelmayer. "Application of High-Speed OH-PLIF Technique for Improvement of Lean Hydrogen-Air Combustion Modeling". En 2016 24th International Conference on Nuclear Engineering. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/icone24-60130.

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The presented work aims to improve CFD explosion modeling for lean hydrogen-air mixtures on under-resolved grids. Validation data is obtained from an entirely closed laboratory scale explosion channel (GraVent facility). Investigated hydrogen-air concentrations range from 6 to 19 vol.-%. Initial conditions are p = 1 atm and T = 293 K. Two highly time-resolved optical measurement techniques are applied simultaneously: (1) 10 kHz shadowgraphy captures line-of-sight integrated macroscopic flame propagation; and (2) 20 kHz OH-PLIF (planar laser-induced fluorescence of the OH radical) resolves microscopic flame topology without line-of-sight integration. This paper presents the experiment, measurement techniques, data evaluation methods and initial results. The evaluation methods encompass the determination of flame tip velocity over distance and a detailed time-resolved quantification of flame topology based on OH-PLIF images. One parameter is the length of wrinkled flame fronts in the OH-PLIF plane obtained through automated post-processing. It reveals the expected enlargement of flame surface area by instabilities on microscopic level. A strong effect of mixture composition is observed.
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