Academic literature on the topic 'Oxygène singulet'
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Journal articles on the topic "Oxygène singulet"
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CaMinade, Anne Marie, Fayez El Khatib, Max Koenig, and Jean Marie Aubry. "Ozonides de phosphite source d'oxygène singulet: rendement, mécanisme." Canadian Journal of Chemistry 63, no. 11 (November 1, 1985): 3203–9. http://dx.doi.org/10.1139/v85-530.
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The ozonides of several phosphites in solution in dichloromethane have been reacted with some scavengers of singlet oxygen (1O2) like rubrene (2), tetraphenylcyclopentadienone (4), and 9,10-diphenylanthracene (6). These ozonides react on the scavengers (−47 °C < t <30 °C) upon their decomposition. The Foote curves obtained by varying the respective concentrations of ozonides and of scavengers lead to parameters similar to those obtained upon the photooxidation of the scavengers by 1O2. Results confirm that these ozonides can lead to the formation of 1O2. The absolute yield of 1O2 is 100% (ρ = 1). These results also confirm the high efficiency of the rubrene toward 1O2 (γ = 1) and the lower efficiency of the tetraphenylcyclopentadienone (γ = 0.46). However, the low value (γ = 0.3) for the efficiency of the 9,10-diphenylanthracene (4) is unexpected.
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Al-Mumen, Haider, Fubo Rao, Wen Li, and Lixin Dong. "Singular Sheet Etching of Graphene with Oxygen Plasma." Nano-Micro Letters 6, no. 2 (March 20, 2014): 116–24. http://dx.doi.org/10.1007/bf03353775.
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Alkahtani, Badr S., Obaid J. Algahtani, Ravi Shanker Dubey, and Pranay Goswami. "Solution of fractional oxygen diffusion problem having without singular kernel." Journal of Nonlinear Sciences and Applications 10, no. 1 (January 29, 2017): 299–307. http://dx.doi.org/10.22436/jnsa.010.01.28.
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Barlow, Clyde H., Katherine A. Kelly, and Jeffrey J. Kelly. "Simultaneous Determination of Hemoglobin and Myoglobin Oxygen Binding Curves by Spectral Curve Fitting." Applied Spectroscopy 46, no. 5 (May 1992): 758–63. http://dx.doi.org/10.1366/0003702924124763.
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A completely optical method is described for the simultaneous determination of hemoglobin and myoglobin oxygen saturation. Solution oxygen concentrations were computed from measurements of phosphorescence decay of a soluble palladium porphyrin using the Stern-Volmer quenching relationship. Visible absorption spectra were recorded of hemoglobin/myoglobin mixtures progressively deoxygenated by bacterial aerobic metabolism. Separate hemoglobin and myoglobin oxygenation curves were resolved from the spectra of solutions containing both proteins by curve fitting, with the use of singular value decomposition of the spectra vs. oxygen concentration matrix. The method yielded a P50 of 1.2 Torr for horse heart myoglobin at 24 ± 1°C, while the P50 for sheep hemoglobin was 23 Torr at the same temperature. These values, obtained from mixtures, compare favorably with literature values determined for hemoglobin and myoglobin separately.
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Gupta, Santosh K., B. Modak, Debarati Das, P. Modak, A. K. Yadav, and K. Sudarshan. "Multiphoton light emission in barium stannate perovskites driven by oxygen vacancies, Eu3+ and La3+: accessing the role of defects and local structures." Physical Chemistry Chemical Physics 23, no. 32 (2021): 17479–92. http://dx.doi.org/10.1039/d1cp02349g.
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The work probes the multicolor emission in BaSnO3 perovskite, singular orange emission in BaSnO3:Eu3+ and quantum yield suppression in BaSnO3:Eu3+, La3+ using XRD, photoluminescence, positron annihilation measurements and DFT calculations.
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Poulet, Patrick, Renée Chabrier, and Thérèse Schunck. "Calorimetrie photoacoustique des réactions de photosensibilisation induites par l'oxygène singulet The photoacoustic calorimetry of photosensitized reactions induced by singlet oxygen." Journal of Optics 28, no. 6 (December 1997): 252–59. http://dx.doi.org/10.1088/0150-536x/28/6/004.
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Sekerci, Yadigar, and Ramazan Ozarslan. "Respiration Effect on Plankton–Oxygen Dynamics in view of non-singular time fractional derivatives." Physica A: Statistical Mechanics and its Applications 553 (September 2020): 123942. http://dx.doi.org/10.1016/j.physa.2019.123942.
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Zuev, Vladimir V., Svetlana L. Bondarenko, and Irina G. Ustinova. "Additive singular spectral model of a dendrochronological signal." Bulletin of the Tomsk Polytechnic University Geo Assets Engineering 334, no. 12 (December 27, 2023): 56–64. http://dx.doi.org/10.18799/24131830/2023/12/4282.
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Relevance. Allocation of structural components in a dendrochronological signal of annual rings of coniferous trees expands the possibilities of the bioindication method and allows obtaining information about changes in environmental conditions in the past for extended territories. Aim. Creation of an additive singular spectral model based on the frequency trigonometric components of the dendrochronological signal; reconstruction of changes in the total ozone content in the atmosphere in the past, affecting the level of ultraviolet radiation in the B range radiation. Objects. Time series of total ozone content in the atmosphere (data from 1932), width and density of annual rings (data from 1686–2004) on the example of the territory near the observatory in Arosa, Switzerland, time series of stable oxygen isotopes δ18Oc, France. Methods. Time series analysis (decomposition of a time series, identification of model parameters, prediction of a time series), statistical analysis (F-criterion, χ2 – Pearson criterion), experimental measurements of the percentage components of the wood of annual rings, correlation analysis, spectral singular analysis. Results. Decomposition of the dendrochronological signal of individual chronologies into trigonometric components in the Caterpillar program. Correlation analysis of the sensitivity of trees to atmospheric effects. Reconstruction of the ozone level in the stratosphere using the first trigonometric component of the dendrochronological signal. In cellulose, the first low-frequency component of the signal and the structural component of wood, a reliable response of trees to long-period fluctuations in the total ozone content is recorded. This allows assessment of the impact of the stress factor on conditions of exploitation of forest resources. The use of data on the width of the annual rings allows you to expand the territorial boundaries of the method.
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Zhang, Feng, Jilin Fan, Fei Qiu, Bing Xie, Xianghui Li, and Hui Zhang. "An enhanced accuracy method to determine oil saturation by carbon/oxygen logging in tight reservoirs." GEOPHYSICS 87, no. 2 (February 1, 2022): D21—D31. http://dx.doi.org/10.1190/geo2021-0309.1.
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The low porosity and permeability characteristics of tight oil reservoirs have brought challenges to monitoring oil saturation recently. Although carbon/oxygen logging is effective for oil saturation evaluation, the statistical fluctuations of the measured energy spectrum in tight reservoirs make it impossible to distinguish the different signals between oil and water. Thus, noise adjusted singular-value decomposition (NASVD) is applied to denoise the raw energy spectrum and evaluate the oil saturation quantitatively. The energy spectrum matrix, which is composed of the energy spectrum of the measurement point and its adjacent depth points, is decomposed and reconstructed to remove noninformative signals and improve the signal-to-noise ratio of the raw energy spectrum. The parameter K evaluates the smoothness of the logging curves, reflecting the influence of the number of energy spectra and singular values on NASVD. Meanwhile, the NASVD, Savitzky-Golay filtering, and depth averaging methods are compared for calculating the accuracy of C/O, Si/Ca, and oil saturation with the Monte Carlo method, indicating that the NASVD is better than the other two methods for eliminating the statistical fluctuations of the raw energy spectrum. A simulation example indicates that the NASVD can control the calculation errors of tight reservoir oil saturation to within 15%, which significantly improves the accuracy of the estimated oil saturation. An oil field example indicates that the oil saturation interpretation result for tight reservoirs is in good agreement with the oil saturation from open-hole log analysis, signifying that the NASVD energy spectrum denoising method can provide a quantitative estimate of oil saturation in tight oil reservoirs.
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Roul, Pradip, and Ujwal Warbhe. "A New Homotopy Perturbation Scheme for Solving Singular Boundary Value Problems Arising in Various Physical Models." Zeitschrift für Naturforschung A 72, no. 8 (August 28, 2017): 733–43. http://dx.doi.org/10.1515/zna-2017-0141.
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AbstractThe classical homotopy perturbation method proposed by J. H. He, Comput. Methods Appl. Mech. Eng. 178, 257 (1999) is useful for obtaining the approximate solutions for a wide class of nonlinear problems in terms of series with easily calculable components. However, in some cases, it has been found that this method results in slowly convergent series. To overcome the shortcoming, we present a new reliable algorithm called the domain decomposition homotopy perturbation method (DDHPM) to solve a class of singular two-point boundary value problems with Neumann and Robin-type boundary conditions arising in various physical models. Five numerical examples are presented to demonstrate the accuracy and applicability of our method, including thermal explosion, oxygen-diffusion in a spherical cell and heat conduction through a solid with heat generation. A comparison is made between the proposed technique and other existing seminumerical or numerical techniques. Numerical results reveal that only two or three iterations lead to high accuracy of the solution and this newly improved technique introduces a powerful improvement for solving nonlinear singular boundary value problems (SBVPs).
Dissertations / Theses on the topic "Oxygène singulet"
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Dodeller, Marc. "Analyse par spectrométrie de masse de l'oxygène moléculaire singulet et de protéines potentiellement ciblées au sein de cellules tumorales lors de la thérapie photodynamique." Metz, 2007. http://docnum.univ-lorraine.fr/public/UPV-M/Theses/2007/Dodeller.Marc.SMZ0753.pdf.
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La thérapie photodynamique (PDT) repose sur l'utilisation d'une molécule photoactive telle que le Foscan® (m-THPC). Ce médicament de seconde génération combiné à la lumière et à l'oxygène, induit la mort cellulaire soit par nécrose soit par apoptose. La première étape de nos études consiste à détecter par MALDI-TOF/MS, dans des cellules HT29 intactes (acénocarcinome du colon humain), l'oxygène singulet produit par le Foscan® (Biolitec Pharma Ldt, Dublin, Irlande) ainsi que la distribution des protéines des cellules après PDT. Le MALDI-TOF/MS a été utilisé pour mettre en évidence l'ortho-benzoylbenzène(o-BB) produit de réaction entre l'oxygène singulet généré par le Foscan® pendant le traitement PDT et le 1. 3-diphenylisobenzofurane (1,3-DPBF, sonde spécifique de l'oxygène singulet). Cette technique permet non seulement le suivi du comportement du photosensibilisateur in situ mais également la détection directe de l'oxygène singulet dans les cellules HT29 intactes. La seconde partie de nos travaux aborde le stress oxydatif induit au niveau des cellules HT29 après PDT. Pour ce faire, nous avons eu recours au gel 2D SDS-PAGE afin d'accéder à la distribution de protéines des HT29, une approche protéomique a ensuite été effectuée par spectrométrie de masse de MALDI-FT-ICR (9. 4 T, Ion Spec Varian, Californie, USA). Grâce au logiciel Imagemaster 2D platinium, la visualisation de la sous expression de quelques protéines a été possible. L'empreinte protéique spécifique de ces protéines fut caractérisée par MALDI-FT-ICR/MS) et les premiers résultats indiqueraient que les protéines de la famille des disulfides isomérases seraient sollicitées lors des processus de PDTPhotodynamic therapy (PDT), uses a photosensitizing molecule such as 5,10,15,20-tetrakis(m-hydroxyphenyl) chlorin (m-THPC, Foscan®), a second generation drug which is specially targeted tumoural tissue with a good selectivity, light and oxygen, inducing cell death by necrosis or apoptosis. Firstly, our studies consist to detect by MALDI-TOF/MS, in intact HT29 cells (adenocarcinoma human colon), singlet oxygen generated by Foscan® (Biolitec Pharma Ldt, Dublin, Irlande) and the protein cells distribution after PDT treatment. A MALDI-TOF mass spectrometer was used to highlight ortho-benzoïbenzene (o-BB) resulting from the reaction between singlet oxygen generated by Foscan® during PDT treatment and 1,3-diphenylisobenzofurane (1,3-DPBF, a specific singlet oxygen quencher). This technique allows the following of the in situ behaviour of the photosensitizer and to detect the presence of singlet oxygen directly in intact HT29 cells. We have also studied the oxidative stress induced by PDT treatment on HT29 cells. After 2D gel SDS-PAGE step in order to observe the protein distribution, proteomic approach is carried out by MALDI-FTICR mass spectrometry (9,4 T, Ion Spec Varian, California). Thnaks to ImageMaster 2D platinium software, we are able to visualize under expression of some proteins. The proteinic finger printings is then characterized by MALDI-FT-ICR/MS and the first results indicate that proteins of dislfide Isomerase family should be implied in PDT processes. MALDI-TOF/MS and MALDI-FTICRMS (9,4 T) appear to be a sensitive and reliable analytical tool (add to UV/Visible anf fluorescence spectroscopy) for the mechanism of PDT understanding
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Khatib, Fayez El. "Nouveaux modèles d'ozonides phosphorés générateurs d'oxygène singulet." Toulouse 3, 1986. http://www.theses.fr/1986TOU30002.
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Apres une mise au point detaillee sur l'ozone et l'oxygene singulet presentee dans le premier chapitre, l'addition oxydante de l'ozone sur le doublet libre des phosphites est etudiee. En faisant varier l'environnement autour de l'atome de phosphore, cette reaction conduit a la formation d'adduits ozonides penta ou hexacoordines. La troisieme chapitre, comporte l'etude de stabilite de ces nouveaux modeles d'ozonides. Ceux-ci se decomposent en generant de l'oxygene singulet. Dans le quatrieme chapitre, le rendement en oxygene singulet est determine, permettant de proposer un mecanisme reactionnel. A la recherche de nouveaux modeles d'ozonides, nous avons etudie la reaction de l'ozone sur des modeles moleculaires comportant la liaison phosphore-azote. Ces molecules fixent de diverses manieres de grandes quantites d'ozone pour conduire a des oligomeres peroxydiques
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Panafieu, Pierre. "Étude d'une décharge luminescente d'oxygène par spectroscopie V. U. V." Paris 11, 1986. http://www.theses.fr/1986PA112139.
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Ce travail présente l'étude de la colonne positive d'une décharge continue d'oxygène à basse pression (0,2 - 5 Torr). Les concentrations d’O2 (X3∑), O2 (1a∆), 0, 03 sont déterminées par spectroscopie d’absorption dans l'ultraviolet sous vide. Les problèmes spécifiques à l'absorption dans l’U. V. Lointain sous vide sont exposés (choix de la longueur d'onde incidente, mise au point de la source U. V. , problèmes liés à l'auto absorption ainsi que les solutions expérimentales retenues. Une attention particulière est portée à la description de la méthode de dosage de l'oxygène atomique, laquelle a nécessité la mesure du profil de la raie source avec une grande précision. Les résultats expérimentaux obtenus sont présentés. Pour chacune des espèces O, O2 (1∆), O3, ne l'influence des paramètres de la décharge (E/N et I) est mise en évidence. Les caractéristiques électriques de la décharge (champ électrique et densité électronique) sont mesurées par sondes électrostatiques et cavité R. F. Respectivement. Un modèle cinétique simple destiné à rendre compte des résultats expérimentaux est établi. Ce modèle inclut les espèces dosées, Il comprend 13 équations traduisant dans nos conditions expérimentales les réactions prépondérantes pour chacune des espèces citées. Le système d'équations différentielles couplées représentant les processus de gain et de perte pour chaque espèce est résolu par une méthode numérique à pas variable (AdamsMoulton). Les résultats numériques obtenus sont comparés aux résultats expérimentaux ainsi qu'aux résultats d'autres modèlesThis work deals with the study of the positive column of a d. C. Low pressure (0, 2 - 5 Torr) oxygen discharge. The concentrations of O2(X3∑), O2(1a∆), O and O3 have been measured by V. U. V. Absorption spectroscopy. The variation of these concentrations with the reduced electric field E/N and the discharge current are presented. The electric field and the electronic density are measured by electrostatic probes and R. F. Cavity. A simple kinetic model including O2, O2 (1∆), O, O3, ne, 0+2 and 0-, has been developed. A numerical integration of the system of 13 differential equations is presented. The experimental results are compared to the results of this model and to the results of literature
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Bouirig, Hassan. "Formation et réactivité de l'oxygène singulet photosensibilisé par l'hypéricine dans des liposomes de dipalmitoylphosphatidylcholine." Grenoble 1, 1992. http://www.theses.fr/1992GRE10114.
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Le travail presente dans ce memoire porte sur l'etude spectroscopique et photophysique de l'hypericine dans des membranes modeles (liposomes de dppc) en liaison avec ses proprietes phototoxiques. Cette etude (spectres d'absorption s#ns#o et t#ns#o, de fluorescence, cinetique de la desactivation de t#1 par transfert intermoleculaire d'energie) montre que l'hypericine photosensibilise avec un bon rendement la formation d'oxygene singulet et nous permet de proposer l'hypericine comme agent phototherapique. La diffusion interliposomique de l'hypericine a ete mise en evidence en utilisant l'autoextinction de la fluorescence qui se produit dans la phase lipidique. Les experiences sur la photooxydation du diphenylisobenzofuranne, sensibilisee par l'hypericine nous ont permis d'etablir le mecanisme de formation et les parametres cinetiques de la diffusion et de la desactivation de l'oxygene singulet a l'interieur et a l'exterieur des liposomes. L'analyse des resultats a amene a proposer un schema cinetique dans lequel apparait deux types d'oxydations: une oxydation rapide (k#r=(0. 90. 2). 10#7m##1. S##1) provoquee par l'oxygene singulet et une oxydation retardee (k#r=(3. 30. 6. 10#5m##1. S##1) qui pourrait etre due a la formation d'un peroxyde
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Cayla, Mattéo. "Catalyseurs contrôlables par l’oxygène singulet : conception, synthèse et propriétés." Electronic Thesis or Diss., Bordeaux, 2024. http://www.theses.fr/2024BORD0419.
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La catalyse modulable vise à contrôler l’activité catalytique par la modification réversible du site catalytique, sous le contrôle d’un stimulus. Les stimuli connus pour les systèmes artificiels sont chimiques (molécules, ions), physiques (température, lumière) ou électrochimiques (rédox). Ces stimulus contrôlent le passage d’un état à l’autre du catalyseur, donc, par conséquence, l’activité du système catalytique en termes de cinétique et de sélectivités des réactions. Afin d’élargir le champ des applications de la catalyse modulable, une stratégie innovante serait d’introduire un nouveau stimulus pour engendrer des modulations inédites. Ces travaux de doctorat ont ainsi visé à montrer que la catalyse peut être modulée par l’oxygène singulet. Les réactions de cycloaddition [4+2] entre 1O2 et les dérivés du 9,10-diphénylanthracène permettent la formation de 9,10-endopéroxydes de façon quantitative et réversible par le biais d’une cycloréversion thermique. De plus, cette réaction engendre une modification structurelle importante, en transformant un composé polyaromatique plan en un produit endopéroxyde à géométrie concave. Ainsi, un site catalytique pourvu de dérivés anthracènes pourrait avoir deux arrangement spatiaux différents, contrôlé par 1O2 et la chaleur. Une nouvelle famille de catalyseurs modulables a été conçue à partir d’acides phosphoriques chiraux dérivés du (R)-BINOL (1,1’-bi-2-naphtol) substitués par des dérivés anthracènes. La cycloaddition de l’oxygène singulet sur ces dérivés a été optimisée pour obtenir des molécules dont la géométrie et la nature du site catalytique sont modifiés. Les propriétés catalytiques des édifices anthracènes et endopéroxydes ont ensuite été évaluées à l’aide de trois réactions modèles (désymétrisation d’oxétane, aza-Friedel-Crafts et désaromatisation de 2-naphtols). Ces réactions ont ensuite été étudiées par modélisation moléculaire pour une compréhension fine des relations entre la structure et l’activité catalytique. Sur la base des calculs DFT, une optimisation des structures des catalyseurs et de nouvelles réactions modèles ont aussi été proposés. Les résultats obtenus constituent une avancée vers une preuve de concept pour l’utilisation de 1O2 en tant que stimulus en organocatalyse, malgré la complexité chimique induite sur les catalyseurs modèles dérivés des acides phosphoriques chirauxSwitchable catalysis aims to control catalytic activity by modulating the system’s catalytic site, when under the influence of a stimulus. The known stimuli that regulate artificial catalytic systems are chemical (molecules, ions), physical (temperature, light) or electrochemical (redox). These stimuli control the switch between states of the catalyst and of its activity, with effects on its catalytic efficiency, regio- or stereo- selectivity. To broaden the field of applications of switchable catalysis, an innovative strategy would consist in introducing a new stimulus that induces unprecedented modulations. This doctoral work aimed to show that catalysis can be modulated by singlet oxygen. [4+2] cycloaddition reactions between 1O2 and 9,10-diphenylanthracene derivatives allows the formation of the corresponding endoperoxides in a quantitative and reversible (with a cycloreversion via thermolysis) manner. Furthermore, this reaction induces a consequent structural modification, transforming a flat polyaromatic into a endoperoxide product with a concave geometry. Thereby, a catalytic site bearing anthracenes could have two spatial arrangements, controlled by 1O2 and heat. A new family of modular catalysts have been designed from (R)-BINOL (1,1’-bi-2-naphtol) based chiral phosphoric acids, substituted by anthracene moieties. The cycloaddition reaction of singlet oxygen onto these derivatives was optimized to efficiently obtain molecules whose geometry and nature of the catalytic site are modified. The catalytic properties of the anthracene- and endoperoxide-based architectures were then evaluated using three model reactions (oxetane desymmetrization, aza-Friedel-Crafts and 2-naphtol derivatives dearomatization). These reactions were then studied by molecular modelling to refine the comprehension of the structure-activity relation of these catalysts. On the basis of DFT calculations, paths of improvement for the catalysts and the optimisation of the catalysed reactions were proposed. The obtained results are an initial base for the proof of concept for the use of 1O2 as a stimulus in organocatalysis, despite the chemical complexity induced on the model catalysts derived from chiral phosphoric acids
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Tournaire, Cécile. "Inhibition de l'oxygène singulet et de l'anion superoxydé par les flavonoi͏̈des. Etude structure-réactivité." Toulouse 3, 1992. http://www.theses.fr/1992TOU30075.
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Les proprietes anti-oxydantes potentielles des flavonoides suscitent beaucoup d'interet. Ils sont capables d'inhiber la peroxydation des lipides mais les etudes quantitatives sont delicates dans ce domaine car l'efficacite antilipoperoxydante depend des conditions experimentales et en particulier du procede d'initiation de la peroxydation. Il est egalement difficile de determiner le mecanisme antilipoperoxydant dans un systeme biochimique complexe. L'inhibition de l'oxygene singulet, espece activee de l'oxygene impliquee dans des processus oxydatifs, peut par contre, etre quantifiee en combinant deux methodes. En effet, la constante de vitesse (k#r) de la reaction de photooxydation des flavonoides peut etre obtenue soit par des mesures cinetiques par spectrophotometrie uv, soit en mesurant l'oxygene consomme a l'aide d'une electrode de clark. Des mesures de luminescence de l'oxygene singulet (stern-volmer) en presence de flavonoides permettent parallelement, de determiner la somme des constantes de desactivation physique (k#q) et chimique (k#r) de l'oxygene singulet par ces composes. Des constantes de vitesse de la reaction chimique comprises entre 0,710#4l. Mol##1s##1 et 11,510#5l. Mol##1s##1; et de desactivation physique comprises entre 0,710#5l. Mol##1s##1 et 78,010#5l. Mol##1s##1 ont ete mesurees. L'influence de la structure de 14 flavonoides sur la reactivite avec l'oxygene singulet, met en evidence les elements determinants de leur structure pour que la reaction chimique ait lieu ou pour que la desactivation physique soit efficace. Cette structure particuliere est egalement necessaire pour l'oxydation des flavonoides par l'anion superoxyde, dont le mecanisme a ete etudie en presence de ko#2 en phase heterogene. Bien que les mecanismes d'oxydation soient differents, l'oxydation des flavonoides par l'oxygene singulet et par l'anion superoxyde (lorsqu'elle a lieu) conduit aux memes produits d'oxydation
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Praseuth, Danièle. "Photodégradation d’un ADN de plasmide induite par les porphyrines hydrosolubles : relation entre la structure des colorants et leur efficacité photodynamique." Paris 11, 1985. http://www.theses.fr/1985PA112051.
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Les porphyrines cartioniques méso-substituées interagissent efficacement avec l’ADN in vitro. Le mode d’interaction dépend de la structure des groupents en méso et dans le cas des métallo-porphyrines, de la géométrie autour du métal. L’intercalation est possible dans le cas des porphyrines les moins encombrées. Les porphyrines base libre ou celles couplées avec un métal diamagnétique sont de bons photosensibilisateurs et produisent en présence de lumière visible de l’oxygène singulet avec des rendements élevés. Ces molécules sont capables d’induire avec une grande efficacité une photodégradation de l’ADN pBR322 in vitro. Ces propriétés laissent présager leur utilisation possible dans le domaine de la photothérapie du cancer.
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Hecka, Audrey. "Caractérisation par spectrométrie de masse d'extraits de millepertuis potentiellement utilisables en photodiagnostic et photothérapie des cancers : étude de leurs propriétés photochimiques en solution et en milieu cellulaire." Thesis, Metz, 2009. http://www.theses.fr/2009METZ052S/document.
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La thérapie photodynamique (PDT) associe la lumière à un agent photosensibilisateur, qui dans l’idéal se localise spécifiquement dans les tissus cancéreux. Illuminé dans le visible, ce photosensibilisateur génère de l’oxygène moléculaire singulet (1O2) et des espèces radicalaires toxiques pour les cellules. Sa fluorescence peut également servir à diagnostiquer les lésions néoplasiques : il s’agit du photodiagnostic (PDD). Les extraits de Millepertuis, connus pour leur activité antidépressive, contiennent également des composés photoactifs, dont l’hypéricine, objet de nombreux travaux dans le cadre de la PDT et du PDD. Cependant, son coût de production est élevé et son utilisation limitée par un manque de solubilité en milieu physiologique. Dans ce contexte, la présente étude vise à évaluer le potentiel des extraits de Millepertuis pour la PDT et le PDD. Le matériel végétal utilisé a dans un premier temps fait l’objet d’analyses par Spectrométrie de Masse (SM) in situ afin de caractériser les molécules photoactives au niveau même des structures végétales impliquées dans leur production. Ces composés ont ensuite été extraits par un solvant organique, et ce mélange a fait l’objet d’études photochimiques visant à quantifier sa production d’1O2 sous illumination laser. La composition des extraits a ensuite été étudiée par désorption/Ionisation Laser couplée à la SM (TOF et FTICR), et par Ionisation Electropray couplée à la FTICRMS. Puis, ils ont fait l’objet d’études en milieu cellulaire (cancer de la vessie), visant à déterminer leur cytotoxicité à l’obscurité, les cinétiques d’internalisation des composés photoactifs, leur phototoxicité et la nature des composés internalisésPhotodynamic therapy (PDT) combines light with a drug called photosensitizing agent, which preferentially accumulates in cancerous cells. Irradiated with visible light, this photosensitizing agent generates singlet oxygen (1O2) and radicals that demonstrate cell toxicity. Fluorescence of this drug also allows diagnosing neoplasic lesions: this is photodynamic diagnosis (PDD).St John’s Wort extracts, mainly known for their antidepressant activity, also contain photoactive compounds, including hypericin which has been extensively studied for PDT and PDD. However, producing this molecule in large amounts is expensive and its use is restricted by a poor solubility in physiological medium. In this context, the present study deals with determining in what extent St John’s Wort extracts could be useful for PDT and PDD. Flowers that were used in this work were firstly in situ-analyzed by mass spectrometry in order to characterized photoactive compounds at the level of structures involved in their biosynthesis. These compounds were then extracted by organic solvent and the resulting mixture subjected to singlet oxygen production measurements under laser illumination. Qualitative analysis of the extracts was then performed either by Laser Desorption/Ionization or Electrospray Ionization coupled with Mass Spectrometry (TOF and FTICR). Finally, their behavior in cellular medium (bladder cancer) was investigated in terms of dark cytotoxicity, intracellular accumulation of photoactive compounds, phototoxicity and characterization of compounds absorbed by cells
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Galland, Margaux. "Conception de sondes théranostiques moléculaires impliquand la PDT à excitation biphotonique." Thesis, Lyon, 2018. http://www.theses.fr/2018LYSEN020.
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La thérapie photodynamique (PDT) est une technique thérapeutique qui permet un traitement localisé par irradiation lumineuse d’un photosensibilisateur (PS) grâce à la génération d’une espèce cytotoxique, généralement de l’oxygène singulet. Cependant, de nombreux PS sont également luminescents et les deux processus sont compétitifs. L’emploi de métaux de transition est connu pour améliorer le processus de PDT mais l’impact des ions lanthanides(III) en PDT est encore peu connu. Par ailleurs, l’utilisation de l’absorption biphotonique a de nombreux avantages parmi lesquels la possibilité d’exciter le PS dans la fenêtre de transparence biologique pour des applications en milieux biologiques.Les travaux de cette thèse visent à étudier quel est l’influence de la complexation d’un atome de lanthanide(III) à un PS sur la photophysique de désexcitation de ce dernier. Les complexes synthétisés et ceux étudiés ont montré que l’effet dépend du lanthanide(III). Il est ainsi possible, avec un choix judicieux du métal, de favoriser une voie de désexcitation par rapport à une autre. En particulier, l’ion Gd(III) se révèle avoir un effet bénéfique important pour la génération d’oxygène singulet et cet effet s’ajoute à celui que des atomes lourds comme le brome peuvent avoir. L’ion Yb(III) en revanche, favorise de manière générale le transfert d’énergie par effet d’antenne et la luminescence du lanthanide est alors le processus majoritaire. Enfin, l’emploi de Gd(III) complexé à un PS excitable à deux photons ouvre la voie à des agents théranostiques moléculaires combinant l’IRM en tant que fonction d’imagerie et la PDT pour la thérapiePhotodynamic Therapy (PDT) is a therapeutic technique which consists in generating a highly reactive species, generally singlet oxygen, by shining light on a photosensitizer (PS). However, many PS are also luminescent and both processes are competitive. The use of transition metals is well known to enhance the PDT effect, but little is known about the effect of lanthanide(III) metals.On the other hand biphotonic absorption has numerous advantages, among them the possibility to excite the PS in the so-called biological transparency window for biological applications.The aim of this PhD is to get a better comprehension of the effect of complexation of a lanthanide(III) atom with a PS on the photophysics and deactivation pathways of the latter. The synthesis and conducted studies of lanthanide complexes showed that the effect is dependent on which lanthanide(III) metal is used. Thus by choosing carefully the lanthanide metal, one can favor one deactivation pathway over another. In particular, the Gd(III) ion turns out to be very efficient in promoting singlet oxygen generation and its effect is additive to the already known positive effect of heavy atoms such as bromine. On the opposite, the Yb(III) ion mainly favors the energy transfer through the antenna effect and the complex preferentially emits light.Finally, using Gd(III) linked to a two-photon excited PS opens the path to molecular theranostic probes combining MRI as a imagery technique and PDT as a therapeutic one
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Bouttemy, Sabine. "Utilisation en synthèse organique de la source chimique d'oxygène singulet H2O2/MoO42- : choix d'un milieu réactionnel adapté à la péroxydation des substrats organiques : eau ou microémulsion." Lille 1, 1996. http://www.theses.fr/1996LIL10007.
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Une source chimique d'oxygène excité à l'état singulet 1O2 constituée du système, peroxyde d'hydrogène/molybdate de sodium, a été utilisée pour oxyder, à une échelle préparative, des composés organiques appartenant aux familles des terpènes, des hétérocycles, des hydrocarbures aromatiques polycycliques, des sulfures, des phénols et des dérivés acryliques. Le milieu réactionnel a été sélectionné en fonction de l'hydrosolubilité du substrat : eau ou microémulsion (dichlorométhane/butanol/dodécylsulfate de sodium/eau). Le choix de la composition de la microémulsion s'est effectué en construisant une série de diagrammes de phases pseudo-ternaires qui ont permis de visualiser l'influence, du rapport cotensioactif/tensioactif, de la nature du solvant organique et de la concentration en molybdate de sodium sur la stabilité du système. Le comportement cinétique de l'oxygène singulet dans ce milieu a été étudié par un montage de photolyse éclair. Nous avons vérifié que la microémulsion se comporte cinetiquement comme un solvant homogène vis-à-vis de l'oxygène singulet quoiqu'un effet de la microstructure du milieu ait été clairement mis en évidence. Enfin, nous avons entrepris l'oxydation, à l'échelle préparative, du citronellol, précurseur de l'oxyde de rose. La mise au point de la formule optimale de la microémulsion, conduisant à une oxydation complète d'une concentration maximale en citronellol sans provoquer de demixtion, n'a pu être réalisée par l'approche scientifique traditionnelle en raison du nombre élevé de paramètres et des interactions qui les lient. Nous avons eu recours à une méthode séquentielle d'optimisation, le simplex, couplée à une fonction de désirabilité
Book chapters on the topic "Oxygène singulet"
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Vandegriff, Kim D., and Richard I. Shrager. "[22] Hemoglobin-oxygen equilibrium binding: Rapid-scanning spectrophotometry and singular value decomposition." In Methods in Enzymology, 460–85. Elsevier, 1994. http://dx.doi.org/10.1016/0076-6879(94)32060-8.
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Janowitz, Henry D. "Diverticula Diverticulosisl and Diverticulitis." In Your Gut Feelings, 133–45. Oxford University PressNew York, NY, 1994. http://dx.doi.org/10.1093/oso/9780195089356.003.0006.
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Abstract The colon is composed of two groups of muscle layers: an inner, circular layer that surrounds the colon and an outer, longitudinal layer. Although they may occur anywhere along the gastrointestinal tract, diverticula (diverticulum, singular) are most often found in the colon. They are little pouches that line the outer layer of the colon and are formed by its inner and outer layers. They occur at weak points in the colon’s wall. When pressure in the colon rises as the muscles contract to move the contents along, these thin-walled sacs balloon through the outer wall (see Figures 6.1 and 6.2). The location of the diverticula is not due to chance; they form where the blood vessels that supply nutrition and oxygen to the colon enter the bowel and pierce its walls, creating areas of potential weakness.
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Harold, Franklin M. "The Expansion of Life." In On Life, 99–118. Oxford University Press, 2021. http://dx.doi.org/10.1093/oso/9780197604540.003.0008.
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The story of life tells of relentless expansion from obscure beginnings to smother the earth in organized biochemistry. First came the prokaryotes, Bacteria and Archaea, followed some two billion years later by eukaryotic microbes. The latter pattern of organization underpins the rise of multicellular organisms, and their spectacular proliferation over the past 600 million years. There have been no fundamentally new kinds of organisms since, but the rise of mind culminating in humanity may signal a new phase in life’s history. Life has expanded in both quantity and quality, a gyre of mounting size, complexity, and functional capacity; in some elusive sense evolution is progressive. Multicellularity, the key invention, is not singular but happened multiple times in several eukaryotic lineages. The proliferation of higher organisms was probably enabled by increased energy flow, and dependent on the increase in atmospheric oxygen. It is studded with innovations in structure, physiology, and behavior, whose origin is a recurrent theme in evolutionary biology. Novelty is rooted in mutational events at the gene level, supplemented by the acquisition of genes from the outside by both gene transfer and symbiosis, and possibly by other avenues. Chance events were scrutinized and culled by natural selection. There appears to be no intrinsic progressive drive, but natural selection generally favors the more functional and better organized.
Conference papers on the topic "Oxygène singulet"
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Rafidi, Nabil, Wlodzimierz Blasiak, and Ashwani K. Gupta. "High Temperature Air Combustion (HiTAC) Phenomena and its Thermodynamics." In ASME 2014 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2014. http://dx.doi.org/10.1115/imece2014-36312.
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The fundamentals and thermodynamic analysis of High Temperature Air Combustion (HiTAC) technology is presented with focus on industrial furnaces as they are amongst the major energy users. The HiTAC is characterized by high temperature of combustion air having low oxygen concentration. This study provides a theoretical analysis of HiTAC a process from the thermodynamic point of view. The results demonstrate the possibilities of reducing thermodynamic irreversibility of combustion by considering an oxygen-deficient combustion process that utilizes both gas- and heat-recirculation. Furthermore, combustion with the use of oxygen (in place of air) is also analyzed. The results showed that a system which utilizes oxygen as an oxidizer results in higher 1st and 2nd law efficiencies as compared to the case with air as the oxidizer. This study is aimed at providing technical guidance to further improve efficiency of a combustion process which show very small temperature increases due to mild chemical reactions. The significant of these findings are now widely used in industrial furnaces with singular successes on energy savings, pollution reduction and reduced size of the equipment. The exergy analysis too can be used as a technical tool to improve efficiency in combustion processes.
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Khalil, Ahmed E. E., and Ashwani K. Gupta. "Fuel Property Effects on the Fate of Volume Distributed Combustion." In ASME 2016 Power Conference collocated with the ASME 2016 10th International Conference on Energy Sustainability and the ASME 2016 14th International Conference on Fuel Cell Science, Engineering and Technology. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/power2016-59050.
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Colorless Distributed Combustion (CDC) has been shown to provide singular benefits on ultra-low pollutants emission, enhanced stability and thermal field uniformity. To achieve CDC conditions, fuel-air mixture must be properly prepared and mixed with hot reactive gases from within the combustor prior to the mixture ignition. Hot reactive gases reduce the oxygen concentration in the mixture while increasing its temperature. In this paper, the impact of fuel type (methane, propane, and hydrogen enriched methane) on achieving distributed combustion is investigated. A mixture of nitrogen and carbon dioxide was mixed to simulate the hot recirculated gases at different temperatures using normal air upstream of the combustor. Increasing the amounts of nitrogen and carbon dioxide reduced the oxygen concentration within the combustor. Distributed combustion was identified through OH* chemiluminescence distribution across the combustor. For methane, this oxygen concentration varied between 13.8% and 11.2% (depending on the mixture temperature) with some 85% reduction in NO emissions as compared to that without entrainment. Similar behavior was demonstrated with propane and hydrogen enriched methane, albeit at a lower oxygen concentration (13.7%–11.6% and 12.2%–10.5%), to result in 94% and 92% reduction in NO emission, respectively. The inlet gas temperature was varied between 300K and 750K. Experimental data using a variety of fuels showed NO emissions of 1 PPM or less. Analysis and extrapolation of obtained data suggest that distributed combustion can be achieved at an oxygen concentration of 9.5% for hot reactive entrained gases having a temperature of 1800K. This value may be used as a guideline to achieve distributed combustion with ultra-low emission.
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Schroer, Carsten, Valentyn Tsisar, Olaf Wedemeyer, Aleksandr Skrypnik, and Jürgen Konys. "Corrosion in Steel T91 Caused by Flowing Lead–Bismuth Eutectic at 400°C and 10−7 Mass% Solved Oxygen." In 2016 24th International Conference on Nuclear Engineering. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/icone24-60845.
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Specimens produced from two different heats of ferritic/martensitic steel T91 were exposed to oxygen-containing flowing lead–bismuth eutectic (LBE) at 400 °C, 10−7 mass% solved oxygen and flow velocity of 2 m/s, for exposure times between around 1000 and 13,000 h. The occurring phenomena were analyzed and quantified using metallographic cross sections prepared after exposure. Oxidation causes a material loss of <10 μm after 13,000 h, while corrosion initiated by the solution of the steel elements may generally proceed around 15 to 30 μm deep into the material in the same amount of time. Oxide scales formed on both heats of T91 tend to buckle and detach. In the case of one of the investigated heats, a singular event of exceptionally severe solution-based corrosion was observed, with associated local material loss around 1.2 mm after 13,000 h. The results are compared especially with findings at 450 and 550 °C and otherwise similar conditions as well as austenitic steels tested in the identical experimental run.
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Sharma, R. D., A. S. Zachor, and B. K. Yap. "A Feasible Technique for Remote Sensing of Thermospheric Temperature and O-Atom Density." In Optical Remote Sensing of the Atmosphere. Washington, D.C.: Optica Publishing Group, 1990. http://dx.doi.org/10.1364/orsa.1990.tud8.
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Atomic oxygen and translational temperature play vital roles in the chemistry and heat balance of the earth's atmosphere above 80 km. However, existing techniques, both in situ and remote, for measuring vertical profiles of the temperature and O-atom density at these altitudes have severe limitations; see, eg., Zachor and Sharma (1989). Described in the present paper is a new remote sensing technique in which the data is a pair of limb radiance profiles corresponding to the spectrally unresolved 147 μm and 63 μm lines of atomic oxygen (the inter-multiplet transitions 3P0 → 3P1 and 3P1 → 3P2 of the ground electronic state). We outline a retrieval procedure that uses both the onion peeling and global-fit methods to recover temperature and O-atom density between 90 km and 300 km altitude. The global-fit technique (Carlotti, 1988), which provides solution values simultaneously for several altitudes, is used only near 200 km altitude, where a singular Jacobian causes the onion peeling method to diverge. The retrieval procedure was applied to noise-contaminated synthetic data in order to establish basic system requirements for a spaceborne sensor. It is concluded that the proposed remote sensing technique can be implemented with a small cryogenic sensor system based on (non-scanning) Fabry-Perot etalons and detectors having current state-of-the-art performance.
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Hadi, Fatemeh, Vreg Yousefian, Ehsan Sarfaraz, and Gian Paolo Beretta. "Extending Degree of Disequilibrium Analysis for Automatic Selection of Kinetic Constraints in the Rate-Controlled Constrained-Equilibrium Method." In ASME 2018 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2018. http://dx.doi.org/10.1115/imece2018-86509.
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The Rate-Controlled Constrained-Equilibrium (RCCE) is a model reduction scheme for chemical kinetics. It describes the evolution of a complex chemical system with acceptable accuracy with a number of rate controlling constraints on the associated constrained-equilibrium states of the system, much lower than the number of species in the underlying Detailed Kinetic Model (DKM). Successful approximation of the constrained-equilibrium states requires accurate identification of the constraints. One promising procedure is the fully automatable Approximate Singular Value Decomposition of the Actual Degrees of Disequilibrium (ASVDADD) method that is capable of identifying the best constraints for a given range of thermodynamic conditions and a required level of approximation. ASVDADD is based on simple algebraic analysis of the results of the underlying DKM simulation and is focused on the behavior of the degrees of disequilibrium (DoD) of the individual chemical reactions. In this paper, we propose a method, as part of our work-in-progress efforts, that could expand the applicability of the derived constraints. This method involves running DKM calculations for a wider range of initial conditions, appending the results of all these cases one after the other after normalizing, and finally running the ASVDADD method to get a set of ‘universal’ constraints applicable within that range of conditions. The effectiveness and robustness of the derived constraints is examined in hydrogen/oxygen ignition delay simulations and the results are compared with those obtained from DKM. The proof-of-concept results demonstrate the potential of the method for finding ‘universal’ constraints.
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Rivadossi, Luca, and Gian Paolo Beretta. "Validation of the ASVDADD Constraint Selection Algorithm for Effective RCCE Modeling of Natural Gas Ignition in Air." In ASME 2016 International Mechanical Engineering Congress and Exposition. American Society of Mechanical Engineers, 2016. http://dx.doi.org/10.1115/imece2016-65323.
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The Rate-Controlled Constrained-Equilibrium (RCCE) model reduction scheme for chemical kinetics provides acceptable accuracies in predicting hydrocarbon ignition delays by solving a smaller number of differential equations than the number of species in the underlying Detailed Kinetic Model (DKM). To yield good approximations, the method requires accurate identification of the rate controlling constraints. Until recently, a drawback of the RCCE scheme has been the absence of a fully automatable and systematic procedure capable of identifying the best constraints for a given range of thermodynamic conditions and a required level of approximation. A recent paper [1] has proposed a new methodology for such identification based on a simple algebraic analysis of the results of a preliminary simulation of the underlying DKM, focused on the behaviour of the degrees of disequilibrium (DoD) of the individual chemical reactions. The new methodology is based on computing an Approximate Singular Value Decomposition of the Actual Degrees of Disequilibrium (ASVDADD) obtained from the DKM simulation. The effectiveness and robustness of the method has been demonstrated in [1] for some cases of methane/oxygen ignition by considering a C1/H/O (29 species/133 reactions) sub-mechanism of the GRI-Mech 3.0 scheme and comparing the results of a DKM simulation with those of RCCE simulations based on increasing numbers of ASVDADD constraints. The RCCE results are in excellent agreement with DKM predictions for relatively small numbers of RCCE constraints. Here we provide a demonstration of the new method for some cases of shock-tube ignition of a natural gas/air mixture, with higher hydrocarbons approximately represented by propane according to the full (53 species/325 reactions) GRI-Mech 3.0 scheme.
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Boinski, F., O. Dugne, S. Gosse´, E. Brackx, and C. Gue´neau. "XRD and SEM/EDS Study of the Phase Distribution in the UO2 and Carbon Reactional System at High Temperature." In Fourth International Topical Meeting on High Temperature Reactor Technology. ASMEDC, 2008. http://dx.doi.org/10.1115/htr2008-58167.
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Several fissile kernels are considered for the TRISO particles of (Very) – High Temperature Reactors (V)-HTR. Considering uranium as the fissile nucleus, the basic chemical composition of the TRISO fuel is always made of UO2 which can be added by some UC2 carbide. The high level operating temperature of this fuel implies to determine the products formed by the interactions between these two previous compounds. Some UO2 kernels embedded in black carbon were heated in the 1250–1400°C temperature range in order to determine the kinetics of gaseous species formation [1] and the relative stability of the oxide and carbide phases. After High Temperature Mass Spectrometry (HTMS) experiments, the products formed during the interaction between uranium oxide (UO2) and carbon powders were characterized by various global and punctual analysis methods. The XRD diagram showed the presence of UO2 and UC phases. The contrasts of density observed by SEM in the Quadrant Back-Scattering Detector (QBSD) mode also allowed to highlight both oxide and carbide phase distributions within the TRISO kernels. During SEM observations, some particles showed particular profiles resulting from “non-uniform” reactional mechanisms as already described by Lindemer [2]. In other singular cases, the interaction between UO2 and carbon led to the formation of the UC phase in the middle of the kernel, the UO2 phase remaining at the outside part. Complementary EDS analyses confirmed the results on both oxide and carbide phases. By considering the interference energies between the K-ray of carbon and the N-ray of uranium, the study of the ray intensities consolidated the contrast distributions observed in SEM. Thanks to these results, some assumptions are also advanced concerning the dissolution of oxygen in the UC crystalline structure.
Reports on the topic "Oxygène singulet"
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Vandegriff, Kim D., and Richard I. Shrager. Evaluation of Hemoglobin-Oxygen Equilibrium Binding by Rapid-Scanning Spectrophotometry and Singular-Value Decomposition. Fort Belvoir, VA: Defense Technical Information Center, January 1993. http://dx.doi.org/10.21236/ada266407.
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Vandegriff, Kim D., and Richard I. Shrager. Evaluation of Hemoglobin-Oxygen Equilibrium Binding by Rapid-Scanning Spectrophotometry and Singular-Value Decomposition. Fort Belvoir, VA: Defense Technical Information Center, March 1993. http://dx.doi.org/10.21236/ada266453.
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Ross, Peter, Samantha Scott, Marie Noel, and Natasha Klasios. Green/Cheakamus watershed: Water quality report for the 2023 dry season. Raincoast Conservation Foundation, June 2024. http://dx.doi.org/10.70766/955.423.
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Water is essential for life, and steps are needed to understand, protect and restore its health in fish habitat throughout British Columbia. The Raincoast Healthy Waters program was launched in 2023 to establish community-oriented water pollution monitoring in select BC watersheds. Two Healthy Waters sampling events take place every year in each watershed – the first in the dry season (summer), and the second being in the wet season (winter). While the Healthy Waters program typically focuses its work within singular watersheds, this partnership featured two Whistler area watersheds: the Green River, which drains through the Lillooet and Fraser Rivers into the Strait of Georgia (watershed area of 875 km2). and the Cheakamus River which drains south via the Squamish River to Howe Sound (watershed area of 1,034 km2). Combined, these watersheds cover an area of 1,909 km2. This report highlights results from the first dry (summer) season sampling carried out with the support and participation of the Whistler Lakes Conservation Foundation (WLCF). Briefly, the Healthy Waters – WLCF team determined basic water properties (temperature, conductivity, pH, dissolved oxygen and turbidity) in situ at sampling sites on July 27, 2023. Water samples were collected from five water categories, including source water (2 samples), stream and river water (7 samples), road runoff (6 samples), tap water (10 samples – pooled into a single composite sample) and marine water (one sample). Samples were then analysed individually for coliform, metals, nutrients and physical parameters, and pooled by water category for analysis of pesticides, polycyclic aromatic hydrocarbons (PAHs), pharmaceuticals and personal care products (PPCPs), polychlorinated biphenyls (PCBs), alkylphenol ethoxylates, bisphenols, per- and poly-fluoroalkyl substances (PFAS), sucralose and 6PPD Quinone. Overall, the Green/Cheakamus watersheds had relatively good water quality in the dry season, but additional sampling and analysis will provide additional insight into contamination impacts from forest fires, domestic wastewater, industrial chemicals and road runoff on the health of this valued watershed.
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Ross, Peter, Samantha Scott, and Marie Noel. Green/Cheakamus watershed: Water quality report for the 2023/2024 wet season. Raincoast Conservation Foundation, June 2024. http://dx.doi.org/10.70766/9365.56.
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Water is essential for life, and steps are needed to understand, protect and restore its health in fish habitat throughout British Columbia. The Raincoast Healthy Waters program was launched in 2023 to establish community-oriented water pollution monitoring in select BC watersheds. Two Healthy Waters sampling events take place every year in each watershed – the first in the dry season (summer), and the second being in the wet season (winter). While the Healthy Waters program typically focuses its work within singular watersheds, this partnership featured two Whistler area watersheds: the Green River, which drains through the Lillooet and Fraser Rivers into the Strait of Georgia (watershed area of 875 km2). and the Cheakamus River which drains south via the Squamish River to Howe Sound (watershed area of 1,034 km2). Combined, these watersheds cover an area of 1,909 km2. This report highlights results from the first wet (winter) season sampling carried out with the support and participation of the Whistler Lakes Conservation Foundation (WLCF). Briefly, the Healthy Waters – WLCF team determined basic water properties (temperature, conductivity, pH, dissolved oxygen and turbidity) in situ at sampling sites on November 23, 2023. Water samples were collected from five water categories, including source water (2 samples), stream and river water (7 samples), road runoff (6 samples), tap water (10 samples – pooled into a single composite sample) and marine water (one sample). Samples were then analysed individually for coliform, metals, nutrients and physical parameters, and pooled by water category and analysed for pesticides, polycyclic aromatic hydrocarbons (PAHs), pharmaceuticals and personal care products (PPCPs), polychlorinated biphenyls (PCBs), alkylphenol ethoxylates, bisphenols, per- and poly-fluoroalkyl substances (PFAS), sucralose and 6-PPD Quinone. Several contaminant classes were found at higher concentrations in the dry season, but some were higher in the wet season. Overall, the Green/Cheakamus watersheds had relatively good water quality in the wet season, but additional sampling and analysis will provide additional insight into contamination impacts from forest fires, domestic wastewater, industrial chemicals and road runoff on the health of this valued watershed.