Viabilité et vieillissement des semences d'arganier (Arganiaspinosa ...

African Journals Online (AJOL)

Des semences de six génotypes de pieds-mères différents ont été traitées au froid (4 °C) pendant un mois, scarifiées et traitées à l'acide gibbérellique (GA3) pendant 24 heures avant leur mise en germination en présence de la lumière. La viabilité des semences a significativement diminué avec le vieillissement des ...

Aerodynamics of Power Plant Installation

Science.gov (United States)

1981-09-01

th~orique d’environ 5 % pour Ia partie instationnaire, la pricision absolue globale risultante itant, bien entendu, mains bonne ;cette precision...motorisfie done lea souffleries do 1’ONERA au Centre de MODANE-AVREEUX. En coopgration avec l’ONERA deux mithodes do simulation froide des iota. des...validit6 permet un moills’ir contr~le du nivoau absolu des masures at de ce fait sat misux adapt6e h Is comparasion de dif’ferents motaurs. E~n outre

Juif avec les Juifs, Grecs avec les Grecs, psychanalyste avec les psychanalystes,...un problème très catholique

NARCIS (Netherlands)

Vandermeersch, P.M.G.P.

1990-01-01

Avec ce texte j'ai clôturé le 11ème congres de l'A.I.E.M.P.R. (Association Internationale d'Etudes Médico-psychologiques et Religieuses) qui a eu lieu à Anvers du 23 au 26 août 1990 sous ma présidence. J'ai stigmatisé l'usage qu'on commençait à faire de la notion lacanienne de l'ordre symbolique

Studies of magnetism with inelastic scattering of cold neutrons; Etudes de magnetisme realisees a l'aide de la diffusion inelastique de neutrons froids

Energy Technology Data Exchange (ETDEWEB)

Jacrot, B [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1964-07-01

Inelastic scattering of cold neutrons can be used to study some aspects of magnetism: spins waves, exchange integrals, vicinity of Curie point. After description of the experimental set-up, several experiments, in the fields mentioned above, are analysed. (author) [French] La technique de diffusion inelastique des neutrons froids est utilisee pour etudier certains aspects du magnetisme: ondes de spins, integrales d'echange, etude au voisinage du point de Curie, etc. Apres une description de l'appareillage, on analyse diverses experiences effectuees dans les domaines enumeres plus haut. (auteur)

Inflammability of magnesium and its alloys in carbon dioxide either pure or mixed with water vapour, air or oxygen; Inflammabilite du magnesium et de ses alliages dans le gaz carbonique et ses melanges avec la vapeur d'eau, l'air ou l'oxygene

Energy Technology Data Exchange (ETDEWEB)

Baque, P; Chevilliard, C; Darras, R [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1964-07-01

Whereas low contents of metallic additions have only a small influence on the temperature at which magnesium begins to burn in carbon dioxide, an increase in the specific surface area of the samples is likely to reduce it considerably, the self-heating phenomena being then more pronounced. On the other hand, the exact nature of the surrounding atmosphere is a very important factor; thus the temperature at which ignition begins increases with increasing carbon dioxide pressure, decreases very rapidly when the moisture content of this gas increases up to 3000 v.p.m., and decreases regularly when the partial pressure of air or oxygen increases. (authors) [French] Alors que de faibles teneurs en additions metalliques n'ont que peu d'influence sur la temperature d'inflammation du magnesium dans le gaz carbonique, l'augmentation de la surface specifique des echantillons est susceptible de l'abaisser fortement, le phenomene d'autochauffage se trouvant alors accru. D'autre part, la nature exacte de l'atmosphere gazeuse ambiante est un facteur tres important; ainsi la temperature d'inflammation croit avec la pression du gaz carbonique, decroit tres rapidement lorsque sa teneur en humidite augmente jusqu'a 3000 v.p.m., et diminue regulierement lorsque la pression partielle d'air ou d'oxygene augmente. (auteurs)

Effects of Support on the Performance of NiO-Based Oxygen Carriers Effets du support sur les performances de matériaux transporteurs d’oxygène à base d’oxyde de nickel

Directory of Open Access Journals (Sweden)

Baek J.-I.

2011-05-01

Full Text Available The performance of an oxygen carrier for Chemical Looping Combustion varies with the support material used. NiO oxygen carriers were prepared using 60 or 70 wt% NiO and different raw support materials (γ-Al2O3, pseudoboehmite, α-Al2O3, γ-Al2O3 mixed with MgO, hydrotalcite, MgAl2O4, and γ-Al2O3 with added graphite by the mechanical mixing method. Reactivity tests were conducted using a thermogravimetric analyzer (TGA at 950˚C. The oxygen carriers prepared using γ-Al2O3, γ-Al2O3 mixed with a small amount of MgO, hydrotalcite, and MgAl2O4 showed high oxygen transfer capacity, high oxygen utilization, and a high oxygen transfer rate. Graphite addition to γ-Al2O3 did not increase the surface area or reactivity. The use of pseudoboehmite as a support led to a significant decrease in oxygen transfer capacity and severe agglomeration of the oxygen carriers during the redox reaction. The increase in MgO content in the raw support materials decreased the reduction reactivity. The oxygen carriers prepared with α-Al2O3 showed less oxygen transfer capacity than the other oxygen carriers. The differences in the reactivity according to the support type were explained by the relative strength of NiO-support interaction obtained from the temperature-programmed reduction analysis. The reactivity test results in this work indicate that γ-Al2O3 and hydrotalcite could be desirable raw support materials to prepare highly reactive NiO oxygen carriers with high NiO content. Les performances des materiaux transporteurs d’oxygene varient en fonction du support utilise dans le procede de combustion en boucle chimique. Differents materiaux a base d’oxyde de Nickel ont ete synthetises avec des concentrations elevees en NiO, comprises entre 60 et 70 %, sur differents supports (γ-Al2O3, pseudobohemite, α-Al2O3, γ-Al2O3 melangee avec MgO, hydrotalcite, MgAl2O4 et γ-Al2O3 additivees avec du graphite par melange mecanique. Des tests de reactivite ont ete

Thermo-pneumatic canning; Le gainage thermopneumatique

Energy Technology Data Exchange (ETDEWEB)

Gauthron, M [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1958-07-01

In the thermo-pneumatic canning, the fuel is enclosed in its can with a clearance that must be reduced by external heated gas pressure. The principal applications are: a) binding magnesium cans on to uranium in fuel elements of reactors cooled by CO{sub 2} under pressure, b) application of a can to a hollow bar of uranium too thin to resist the pressure of cold hydraulic canning, c) application of an aluminium can to a bar, with an initial diametrical clearance between uranium and can too great to sustain cold hydraulic canning without buckling, d) detection of major leakage in the slugs. (author) [French] Ce procede consiste a appliquer une gaine sur une barre d'uranium par pression hydrostatique d'un gaz chaud. Les principales applications sont: a) le frettage des gaines de magnesium des elements combustibles des piles refroidies au CO{sub 2} sous pression, b) le gainage d'un barreau creux qui serait ecrase a froid, c) le gainage avec un jeu initial trop fort pour etre effectue a froid sans plisser, d) la detection des fuites de cartouches. (auteur)

Le projet SCORE (Superior cold recycling) : Evaluation en laboratoire des proprietes mécaniques des enrobés bitumineux retraités en place par les techniques à froid

OpenAIRE

BROSSEAUD, Y; GAUDEFROY, V; BEGHIN, A; PLACIN, F; DELFOSSE, F; BAENA, JM

2006-01-01

Afin de promouvoir les technologies de construction favorables à l'environnement (Environmentally Friendly Construction Technologies - EFCT) et pour son 5è programme cadre de recherche et développement PCRD, la Commission européenne a décidé de financer un projet de recherche sur le retraitement en place à froid, intitulé SCORE "Superior Cold Recycling based on benefits of bituminous microemulsions and foamed bitumen. A EFCT system for the rehabilitation and the maintenance of roads", et visa...

8 − La bizarre disparité des instruments de la relativité restreinte

OpenAIRE

Stratonovitch , Jean

2014-01-01

Un court texte sans calculs ni formules, accessible même si on est en froid avec les maths.; Einstein construit la cinématique de la relativité restreinte sur trois instruments : le corps « rigide » (à prendre au sens d’« élastique » ou d’« élastiquement rigide »), le « vérificateur de simultanéité » et l’horloge. Les définitions qu’il en donne sont bizarrement disparates : les deux premiers sont explicitement définis, de telle façon que nous sommes capables de les construire et que nous conn...

Study of liquid hydrogen and liquid deuterium cold neutron sources; Etude de sources de neutrons froids a hydrogene et deuterium liquides

Energy Technology Data Exchange (ETDEWEB)

Harig, H D [Commissariat a l' Energie Atomique, Grenoble (France). Centre d' Etudes Nucleaires

1967-12-01

In view of the plant of the cold neutron source for a high flux reactor (maximal thermal flux of about 10{sup 15} n/cm{sup 2}s) an experimental study of several cold sources of liquid hydrogen and liquid deuterium has been made in a low power reactor (100 kW, about 10{sup 12} n/cm{sup 2}s). We have investigated: -cold neutron sources of liquid hydrogen shaped as annular layers of different thickness. Normal liquid hydrogen was used as well as hydrogen with a high para-percentage. -Cold neutron sources of liquid deuterium in cylinders of 18 and 38 cm diameter. In this case the sources could be placed into different positions to the reactor core within the heavy water reflector. This report gives a general description of the experimental device and deals more detailed with the design of the cryogenic systems. Then, the measured results are communicated, interpreted and finally compared with those of a theoretical study about the same cold moderators which have been the matter of the experimental investigation. (authors) [French] En vue de l'installation d'une source a neutrons froids dans un reacteur a haut flux (flux thermique maximal environ 10{sup 15} n/cm{sup 2}s), nous avons fait une etude neutronique experimentale de differentes sources froides a hydrogene et a deuterium liquides aupres d'un reacteur a faible puissance (100 kW environ 10{sup 12} n/cm{sup 2}s). Nous avons etudie: des couches annulaires de differentes epaisseurs d'hydrogene liquide normal et d'hydrogene a grand pourcentage para, des cellules cylindriques de 18 et 38 cm de diametre, remplies de deuterium liquide et placees a differentes positions dans le reflecteur D{sub 2}O. Ce travail traite l'implantation de l'installation cryogenique et donne une description generale de l'experience. L'interpretation des resultats fait etat entre autres d'une comparaison entre l'experience et une etude theorique portant sur les memes moderateurs. (auteurs)

Mass-spectrometric analysis of trace oxygen in carbon dioxide; Analyse de traces d'oxygene dans le gaz carbonique par spectrometrie de masse

Energy Technology Data Exchange (ETDEWEB)

Nief, G; Severin, M [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1961-07-01

The mass spectrum of pure CO{sub 2} contains a peak of weight 32 whose relationship to peak at 44 varies greatly depending on the previous history of the source of ions and even during the course of an analysis. The fact that this peak is more or less proportional to the pressure and that its appearance potential is the same as that of oxygen leads us to suppose that it is produced from oxygen formed by dissociation of the carbon dioxide on the tungsten filament. A prior treatment of the ion source with acetylene reduces the ratio 32/44 to a value of about 15.10{sup -5}. This same treatment also stabilises the spectrometer's sensitivity to oxygen. Two lines of introduction enable pure carbon dioxide, the specimen to be estimated and a reference mixture of known oxygen content to be sent into the mass spectrometer in quick succession. Oxygen in the carbon dioxide in amounts ranging between 0 and 500 p.p.m. can thus be determined to an accuracy of {+-} 5 p.p.m., the analysis taking 30 minutes. (author) [French] Le spectre de masse de CO{sub 2} pur contient un pic de masse 32 dont le rapport au pic 44 varie enormement suivant l'histoire anterieure de la source d'ions et meme au cours d'une analyse. Le fait que ce pic soit grossierement proportionnel a la pression et que son potentiel d'apparition soit le meme que celui de l'oxygene permet de supposer qu'il est engendre a partir de l'oxygene produit par dissociation du gaz carbonique sur le filament de tungstene. Un conditionnement prealable de la source d'ions avec de l'acetylene reduit le rapport 32/44 a une valeur d'environ 15.10{sup -5}. Ce meme traitement stabilise egalement la sensibilite du spectrometre vis-a-vis de l'oxygene. Une double ligne d'introduction de gaz permet d'envoyer en successions rapides dans le spectrometre de masse le gaz carbonique pur, l'echantillon a doser et un melange de reference de teneur en oxygene connue. On arrive ainsi a doser l'oxygene dans le gaz carbonique dans la gamme de 0 a

Auscultation d'ouvrages avec un capteur géotextile à fibres optiques

Directory of Open Access Journals (Sweden)

ARTIERES, Olivier

2012-08-01

Full Text Available Pour évaluer la sécurité d'un ouvrage en terre, il est indispensable de disposer et de pouvoir interpréter des données d'auscultation, mais les mesures sont parfois difficiles à mettre en place et pas toujours fiables sur le long terme. Avec l’insertion de fibres optiques dans un géotextile, la solution TenCate GeoDetect® est le premier système d'auscultation conçu spécifiquement pour les applications géotechniques. Implantée depuis huit ans avec succès sur de nombreux ouvrages, elle permet d’accéder à des informations jusqu’ici très difficiles à obtenir et ceci avec une grande précision.

Profil lipidique des personnes vivant avec le VIH sous antirétroviral ...

African Journals Online (AJOL)

Au regard des connaissances actuelles, aucune étude n'est disponible au Bénin sur le profil lipidique des personnes vivant avec le VIH. L'objectif de la présente étude est de décrire le profil lipidique des personnes vivant avec le VIH sous antirétroviral suivies au CHU-O/P de Porto-Novo. Il s'est agi d'une étude ...

Basic physics with ultra cold neutrons; Physique fondamentale avec des neutrons ultra froids

Energy Technology Data Exchange (ETDEWEB)

Protasov, K. [Laboratoire de Physique Subatomique et de Cosmologie, CNRS-IN2P3, Universite Joseph Fourier, INPG, Grenoble (France)

2007-07-01

A short introduction to the physics of Ultra Cold Neutrons (UCN) is given. It covers different aspects from their discovery, their major properties as well as their using in the three experiments of fundamental physics: measurements of the neutron life time and of its electric dipole moment and studies of neutrons quantum states in the Earth's gravitational field. (author)

Eclipsing Aestheticism: Western Landscape Photography After Ansel Adams

OpenAIRE

Dennis, Kelly

2015-01-01

Bien que l’héritage photographique d’Ansel Adams (1902-84) reste incontestable dans la culture de masse, dans les musées et parmi les collectionneurs, la nature de cet héritage fait débat parmi les artistes contemporains, les chercheurs et les théoriciens de la photographie. Pour certains, à la fin du 20ème siècle, les paysages typiques de Adams représentant l’Ouest américain au milieu du siècle désignaient une connivence secrète avec l’expansion américaine vers l’ouest durant la guerre froid...

Oxygen mobility in alkali feldspars; Etude de la mobilite de l'oxygene dans les feldspaths alcalins

Energy Technology Data Exchange (ETDEWEB)

Merigoux, H [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1968-03-15

The oxygen mobility is shown from oxygen atoms exchange between potassic and sodic feldspars and 18 oxygen enriched water. Exchanges are carried out in autoclaves between 400 and 800 deg. C under a water pressure between 300 and 800 bars. The oxygen is extracted from silicate by a ClF{sub 3} attack. Two distinct mechanisms may be found. The first one is auto-diffusion; for adularia we have: D = 9.10{sup -7} exp(-32000/RT) (cm{sup 2}.s{sup -1}), for albite: D 4.5.10{sup -5} exp(-37000/RT) (cm{sup 2}.s{sup -1}). The second one, more rapid, is associated with alkali atoms exchanges. These results are applied to the order-disorder problem in feldspars and to the oxygen geochemistry. (author) [French] La mobilite de l'oxygene est mise en evidence a partir d'echanges d'atomes d'oxygene entre des feldspaths potassiques et sodiques en presence d'une eau enrichie en oxygene 18. Les echanges sont effectues en autoclave entre 400 et 800 deg. C sous des pressions de vapeur d'eau comprises entre 300 et 800 bars. L'oxygene est extrait du silicate par attaque au ClF{sub 3}. Deux mecanismes, bien distincts, peuvent se rencontrer. Le premier correspond a l'autodiffusion de l'oxygene; dans le domaine etudie on trouve pour l'adulaire: D = 9,10{sup -7} exp(-32000/RT) (cm{sup 2}.s{sup -1}), et pour l'albite: D 4,5.10{sup -5} exp(-37000/RT) (cm{sup 2}.s{sup -1}). Le second, beaucoup plus rapide, est associe a l'echange des atomes alcalins avec la solution. Ces resultats sont appliques au probleme du passage ordre-desordre dans les feldspaths et a la geochimie de l'oxygene. (auteur)

Oxygen mobility in alkali feldspars; Etude de la mobilite de l'oxygene dans les feldspaths alcalins

Energy Technology Data Exchange (ETDEWEB)

Merigoux, H. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1968-03-15

The oxygen mobility is shown from oxygen atoms exchange between potassic and sodic feldspars and 18 oxygen enriched water. Exchanges are carried out in autoclaves between 400 and 800 deg. C under a water pressure between 300 and 800 bars. The oxygen is extracted from silicate by a ClF{sub 3} attack. Two distinct mechanisms may be found. The first one is auto-diffusion; for adularia we have: D = 9.10{sup -7} exp(-32000/RT) (cm{sup 2}.s{sup -1}), for albite: D 4.5.10{sup -5} exp(-37000/RT) (cm{sup 2}.s{sup -1}). The second one, more rapid, is associated with alkali atoms exchanges. These results are applied to the order-disorder problem in feldspars and to the oxygen geochemistry. (author) [French] La mobilite de l'oxygene est mise en evidence a partir d'echanges d'atomes d'oxygene entre des feldspaths potassiques et sodiques en presence d'une eau enrichie en oxygene 18. Les echanges sont effectues en autoclave entre 400 et 800 deg. C sous des pressions de vapeur d'eau comprises entre 300 et 800 bars. L'oxygene est extrait du silicate par attaque au ClF{sub 3}. Deux mecanismes, bien distincts, peuvent se rencontrer. Le premier correspond a l'autodiffusion de l'oxygene; dans le domaine etudie on trouve pour l'adulaire: D = 9,10{sup -7} exp(-32000/RT) (cm{sup 2}.s{sup -1}), et pour l'albite: D 4,5.10{sup -5} exp(-37000/RT) (cm{sup 2}.s{sup -1}). Le second, beaucoup plus rapide, est associe a l'echange des atomes alcalins avec la solution. Ces resultats sont appliques au probleme du passage ordre-desordre dans les feldspaths et a la geochimie de l'oxygene. (auteur)

Angiomyolipome rénal agressif avec extension à la veine rénale: à ...

African Journals Online (AJOL)

Exceptionnellement la tumeur peut avoir un caractère agressive avec extension locorégionale et veineuse (la veine rénale et la veine cave inferieure). Nous présentons une observation d'une patiente âgée de 37 ans présentant un Angiomyolipome rénal volumineux avec extension à la veine rénale. Mots clés: Rein ...

coloproctectomie avec anastomose colo-sus-anale pour tumeur ...

African Journals Online (AJOL)

Une coloproctectomie fut réalisée le 30/06/2014 avec anastomose colo-anale, colostomie de protection sous-couvert d'une transfusion sanguine. L'examen histologique du segment colorectal prélevé objectiva une rectocolite granulomateuse autour de nombreux oeufs de schistosomes. En effet, le patient a vécu à Pahou, ...

Oxygen titration in sodium. The mercury method and its use for very low values; Dosage de l'oxygene dans le sodium. La methode au mercure : son utilisation dans le cas de tres faibles teneurs

Energy Technology Data Exchange (ETDEWEB)

Champeix, L; Darras, R; Duflo, J [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1958-07-01

The mercury method for the oxygen titration in sodium has now been known for ten years and is probably the more frequently used. In this text, precision are given to what extent it is valuable when used in microanalysis. Details are given on the apparatus, its manipulation and its calibration. After testing, we have decided to use flame spectroscopy to titrate the sodium hydroxide formed. Discussions are exposed on the errors due to the presence of sodium chloride and calcium. Results are examined from the point of view of their reproducibility and accuracy. If great care is taken, this method allows oxygen titration in sodium even for values below 10 ppm with satisfactory precision. (author) [French] La methode au mercure pour le dosage de l'oxygene dans le sodium est connue depuis une dizaine d'annees, elle est probablement la plus utilisee. Nous avons voulu preciser dans quelle mesure elle etait valable dans le domaine des faibles teneurs avec une precision acceptable. Nous decrivons en detail l'appareil utilise pour l'analyse, le mode operatoire et la methode d'etalonnage. Nos essais nous ont conduit a adopter la spectrographie de flamme pour le dosage de la soude formee, les erreurs introduites par la presence de chlorure de sodium et de calcium sont discutes. Les resultats obtenus sont examines du point de vue de la reproductibilite, de la justesse. Moyennant un mode operatoire tres soigne, cette methode permet le dosage de l'oxygene dans le sodium, meme a des teneurs inferieures a 10 ppm avec une precision satisfaisante. (auteur)

Avec Orima - Designing the brand identity

OpenAIRE

Nguyen Le Quynh, Nga; Carvalho, Maria Clara da Costa

2016-01-01

The thesis is a document in building the brand image for the authors’ own start-up Avec Orima. It is motivated by the need to take the company from the planning stage to the next very first step of implementing the business – designing the company’s brand identity. The thesis focused on the process of designing the brand identity. The process began with analysing the company and Finnish target market to have the insights on what the company stands for and wants to achieve. The study then ...

Critical sizes and flux distributions in the shut down pile; Tailles critiques et cartes de flux a froid

Energy Technology Data Exchange (ETDEWEB)

Banchereau, A; Berthier, P; Genthon, J P; Gourdon, C; Lattes, R; Martelly, J; Mazancourt, R de; Portes, L; Sagot, M; Schmitt, A P; Tanguy, P; Teste du Bailler, A; Veyssiere, A [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1957-07-01

An important part of the experiments carried out on the reactor G1 during a period of shut-down has consisted in determinations of critical sizes, and measurements of flux distribution by irradiations of detectors. This report deals with the following points: 1- Critical sizes of the flat pile, the long pile and the uranium-thorium pile. 2- Flux charts of the same piles, and study of an exponential experiment. 3- Determination of the slit effect. 4- Calculation of the anisotropy of the lattice. 5- Description of the experimental apparatus of the irradiation measurements. (author) [French] Une part importante des experiences a froid effectuees sur le reacteur G1 a consiste en des determinations de tailles critiques et des mesures de distributions de flux par irradiations de detecteurs. Le present rapport traite les points suivants: 1- Tailles critiques de la pile plate, de la pile longue, de la pile a uranium-thorium. 2 - Cartes de flux des memes piles et etude d'une experience exponentielle. 3 - Determination de l'effet de fente. 4 - Calcul de l'anisotropie du reseau. 5 - Description de l'appareillage experimental des mesures d'irradiations. (auteur)

Critical sizes and flux distributions in the shut down pile; Tailles critiques et cartes de flux a froid

Energy Technology Data Exchange (ETDEWEB)

Banchereau, A.; Berthier, P.; Genthon, J.P.; Gourdon, C.; Lattes, R.; Martelly, J.; Mazancourt, R. de; Portes, L.; Sagot, M.; Schmitt, A.P.; Tanguy, P.; Teste du Bailler, A.; Veyssiere, A. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1957-07-01

An important part of the experiments carried out on the reactor G1 during a period of shut-down has consisted in determinations of critical sizes, and measurements of flux distribution by irradiations of detectors. This report deals with the following points: 1- Critical sizes of the flat pile, the long pile and the uranium-thorium pile. 2- Flux charts of the same piles, and study of an exponential experiment. 3- Determination of the slit effect. 4- Calculation of the anisotropy of the lattice. 5- Description of the experimental apparatus of the irradiation measurements. (author) [French] Une part importante des experiences a froid effectuees sur le reacteur G1 a consiste en des determinations de tailles critiques et des mesures de distributions de flux par irradiations de detecteurs. Le present rapport traite les points suivants: 1- Tailles critiques de la pile plate, de la pile longue, de la pile a uranium-thorium. 2 - Cartes de flux des memes piles et etude d'une experience exponentielle. 3 - Determination de l'effet de fente. 4 - Calcul de l'anisotropie du reseau. 5 - Description de l'appareillage experimental des mesures d'irradiations. (auteur)

Variation of the material laplacian of G1 with the radius of the uranium bar; Variation du laplacien matiere de G1 avec le rayon du barreau d'uranium

Energy Technology Data Exchange (ETDEWEB)

Tanguy, P [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1957-07-01

In this report are described and interpreted some experiments, carried out in the pile G1 during a period of shut-down, which have made it possible to measure the variation of the material Laplacian of the lattice with the radius of the uranium bar. The variation of the reactivity of the pile is measured when an increasing number of fuel elements are progressively replaced in the central region by fuel elements of greater diameter; it is shown that, starting from measurements based on less than ten per cent of the total number of elements, the variation of reactivity corresponding to the replacement of all the elements can be determined; it is then easy to deduce the variations of the Laplacian. Results: the variations of the Laplacian with the uranium rod diameter are 0 (d. 26 mm), +0.065 {+-} 0.004 m{sup -2} (d. 28 mm) and +0.080 {+-} 0.008 m{sup -2} (d. 32 mm). (author) [French] Dans ce rapport sont decrites et interpretees des experiences realisees sur la pile G1 'froide', experiences qui ont permis de mesurer la variation du Laplacien matiere du reseau avec le rayon du barreau d'uranium. On mesure la variation de reactivite de la pile lorsqu'on remplace progressivement dans la region centrale un nombre croissant de cartouches par des cartouches de plus gros diametre; on montre qu'a partir de mesures portant sur moins de dix pour cent du nombre total de cartouches, on peut determiner la variation de reactivite qui correspondrait au remplacement de toutes les cartouches; il est facile d'en deduire les variations du Laplacien. Resultats: les variations du Laplacien en fonction du diametre du barreau d'uranium sont: 0 (d. 26 mm), +0.065 {+-} 0.004 m{sup -2} (d. 28 mm) and +0.080 {+-} 0.008 m{sup -2} (d. 32 mm). (auteur)

Eisenstein contemporain : entretien avec Antonio Somaini

Directory of Open Access Journals (Sweden)

Bruno Leites

2016-04-01

Full Text Available Entretien avec Antonio Somaini à propos des films, des écrits et des dessins de Sergei Eisenstein. Somaini est actuellement un des plus grands spécialistes de l’œuvre d’Eisenstein. À l’entretien, nous parlons de nombreux sujets : les défis de traduire les ouvrages d’Eisenstein, les phases de sa carrière, le développement de sa pensée, la relation de ses films avec ses écrits, sa pratique du dessin et sa passion pour les dessins de Walt Disney. C’est un long entretien dans laquelle nous parlons aussi des principaux concepts d’Eisenstein, tels que l’extase, le pathos, l’organicité, l’attraction, la régression et la plasmaticité. Somaini nous parle également de la spécificité de son travail et de l’urgence de reprendre Eisenstein. D’un côté, il faut le faire sortir de l’histoire du cinéma exclusivement et l’inclure dans le réseau le plus vaste des arts et de la pensée des années 1920, 1930 et 1940. De l’autre côté, il faut penser son projet comme essentiellement contemporain. Comme Somaini l’a dit, ce que nous pensons beaucoup aujourd’hui, le dispositif cinématographique, le rapport entre le cinéma et l’histoire de l’art, l'influence des images sur l’ensemble de l’expérience humaine, cela a toujours été le problème d’Eisenstein.

M. G.-F. Leclerc, Préfet de la Haute-Savoie lors de sa visite dans le tunnel du LHC au Point 2 avec D. Delikaris, Département Technologie; dans la caverne de l'expérience ALICE avec B. Erazmus, Collaboration ALICE et lors de la signature du livre d'or avec F. Bordry, Chef du Département Technologie. P. Fassnacht, Conseiller au Bureau des Relations internationales présent.

CERN Multimedia

Jean-Claude Gadmer

2013-01-01

M. G.-F. Leclerc, Préfet de la Haute-Savoie lors de sa visite dans le tunnel du LHC au Point 2 avec D. Delikaris, Département Technologie; dans la caverne de l'expérience ALICE avec B. Erazmus, Collaboration ALICE et lors de la signature du livre d'or avec F. Bordry, Chef du Département Technologie. P. Fassnacht, Conseiller au Bureau des Relations internationales présent.

Animal Certifié Conforme: Déchiffrer nos Relations avec le Vivant

Directory of Open Access Journals (Sweden)

Daniel W. Gade

2014-01-01

Full Text Available Review of Animal Certifié Conforme: Déchiffrer nos Relations avec le Vivant. Bernadette Lizet and Jacqueline Milliet, eds. 2012. Dunod/Muséum National d’Histoire Naturelle, Paris. Pp 256. €22 (paperback. ISBN 9782100582853.

AVEC 2017 - Real-life depression, and affect recognition workshop and challenge

NARCIS (Netherlands)

Ringeval, Fabien; Schuller, Bjorn; Valstar, Michel; Gratch, Jonathan; Cowie, Roddy; Scherer, Stefan; Mozgai, Sharon; Cummins, Nicholas; Schmitt, Maximilian; Pantic, Maja

2017-01-01

The Audio/Visual Emotion Challenge and Workshop (AVEC 2017) "Real-life depression, and affect" will be the seventh competition event aimed at comparison of multimedia processing and machine learning methods for automatic audiovisual depression and emotion analysis, with all participants competing

Communiquez avec nous | CRDI - Centre de recherches pour le ...

International Development Research Centre (IDRC) Digital Library (Canada)

Communiquez avec nous. Le siège social du CRDI est situé à Ottawa, au Canada. Nos quatre bureaux régionaux nous permettent de rester proches de nos chercheurs et des projets que nous finançons en Asie, en Amérique latine et dans les Caraïbes, au Moyen-Orient et en Afrique du Nord, ainsi qu'en Afrique ...

Mucocele fronto-ethmoïdale geante avec extension intracranienne ...

African Journals Online (AJOL)

Mucocele fronto-ethmoïdale geante avec extension intracranienne: a propos d'un cas et revue de la litterature. A Kabre, DS Zabsonre, Y Haro. Abstract. Les mucocèles sont des pseudotumeurs kystiques développées aux dépens des sinus paranasaux. D'évolution lente et silencieuse elles se révèlent le plus souvent par ...

Philosophie et politique: pour une discussion avec Lansana Keit ...

African Journals Online (AJOL)

Résumé Dans le cadre d'un échange d'idées avec le co-éditeur, Paulin Hountondji aborde dix (10) questions théoriques sur le rôle historique de la pensée critique dans l'établissement des paramètres d'une transformation économique, politique et technologique de la société africaine. L'ensemble des questions soumis à ...

Réponse du fonio blanc (Digitaria exilis Stapf) à l'inoculation avec ...

African Journals Online (AJOL)

SARAH

2016-07-31

Jul 31, 2016 ... (2004) a montré que l'inoculation avec des .... fasciculatum - Go: G. mosseae - Gm: G. manihotis - Ge : G. etunicatum - Gv : G. verriculosum. Les barres ..... dépendantes de la symbiose mycorhizienne car leurs ..... hybrid cv.

Evaluation de la réactivité chimique et de la montée en cohésion au jeune âge des matériaux bitumineux recyclés à froid

OpenAIRE

ODIE, L; NAUDAT, C; BROSSEAUD, Y; BEGHIN, A; PLACIN, F; ECKMANN, B; DELFOSSE, F

2006-01-01

Une des taches du programme de recherche européen SCORE était l'optimisation de la formulation des matériaux bitumineux recyclés à froid. Pour atteindre cet objectif, le LRPC de Saint-Brieuc a développé deux méthodes d'essais qui permettent de mieux appréhender la réactivité chimique entre les fraisats d'enrobé et les émulsions cationiques. La première méthode consiste en une extraction à l'eau acidifiée des fraisats d'enrobés. Le pH de la solution est mesuré tout au long de la procédure d'ex...

Compte-rendu de : Isabelle Stengers, Penser avec Whitehead, Paris : Seuil, 2002, 582p.

Directory of Open Access Journals (Sweden)

Pierre Cassou-Noguès

2006-05-01

Full Text Available L’ouvrage conjoint un double effort, que résume parfaitement le titre : Penser avec Whitehead. Au départ, l’ouvrage se présente comme un commentaire de l’œuvre de Whitehead. Isabelle Stengers cherche à éclairer les textes, souvent difficiles, de Whitehead et cela par ordre chronologique, pour en particulier analyser le passage de l’épistémologie à la cosmologie et les différentes strates de la cosmologie. Whitehead, qui a rédigé avec Russell les Principia Mathematica, commence son œuvre philo...

Une clinique possible avec les malades d’Alzheimer

OpenAIRE

Fontela, Cristina; Darnaud, Thierry

2015-01-01

Dans cet article les auteurs montrent qu’une psychothérapie d’inspiration psychanalytique est possible avec des sujets institutionnalisés présentant une démence du type Alzheimer. Elle se justifie d’autant plus que le sujet a subi des pertes relationnelles et d’objets libidinalement investis. Le clinicien tente de s’adapter à un psychisme en proie aux troubles cognitifs où les mouvements transféro-contretransférentiels sont massifs et ont un rôle particulier dans l’économie psychique du sujet...

Summary for AVEC 2017 - Real-life depression and affect challenge and workshop

NARCIS (Netherlands)

Ringeval, Fabien; Schuller, Björn; Valstar, Michel; Gratch, Jonathan; Cowie, Roddy; Pantic, Maja

2017-01-01

The seventh Audio-Visual Emotion Challenge and workshop AVEC 2017 was held in conjunction with ACM Multimedia'17. This year, the AVECseries addresses two distinct sub-challenges: emotion recognition and depression detection. The Affect Sub-Challenge is based on a novel dataset of human-human

Syndrome d´Apple-Peel avec nécrose intestinale | Khattala | Pan ...

African Journals Online (AJOL)

Syndrome d´Apple-Peel avec nécrose intestinale. Khalid Khattala, Youssef Bouabdallah. Abstract. Pan African Medical Journal 2012; 13:63. Full Text: EMAIL FREE FULL TEXT EMAIL FREE FULL TEXT · DOWNLOAD FULL TEXT DOWNLOAD FULL TEXT · AJOL African Journals Online. HOW TO USE AJOL.

Prépositions et rection verbale étude des prépositions avec, contre, en, par, parmi, pour

CERN Document Server

Ashino, Fumitake; Paillard, Denis

2017-01-01

Cet ouvrage étudie une série de prépositions du français (avec, contre, par, parmi, en et pour) dont la caractéristique commune est d'introduire un terme (Y) constituant un mode d'appréhension particulier du terme (X) avec lequel ces prépositions établissent une relation (X prép Y), et dont un grand nombre d'emplois sont liés à la rection verbale.

Quand la relation biographique vole en éclats. Renaissances. Vivre avec Joyce, Aquin, Yourcenar de Guylaine Massoutre

Directory of Open Access Journals (Sweden)

Frances Fortier

2010-12-01

Full Text Available L’ouvrage récent de Guylaine Massoutre, Renaissances. Vivre avec Joyce, Aquin, Yourcenar présente, à la faveur d’une prose échevelée et lyrique, volontiers baroque, le parcours d’une biographe fictive, elle-même personnage d’une fiction d’Aquin, sur les traces des figures littéraires qui ont déclenché son envie d’écrire. L’étude entend montrer comment cet ouvrage joue avec finesse des ancrages générique, énonciatif, culturel et esthétique de l’exercice biographique. With the help of an unbridled and lyrical prose that is wilfully baroque, the recent work of Guylaine Massoutre, entitled Renaissances. Vivre avec Joyce, Aquin, Yourcenar, presents the course of a fictitious biographer, herself a character of an Aquinian fiction, as she follows the traces of the literary figures who inspired her desire to write. This study intends to show the way in which the work plays ingeniously upon the generic, enunciative, cultural and aesthetic foundations of the biographical endeavour.

Apprendre à programmer avec Python

CERN Document Server

Swinnen, Gérard

2009-01-01

Quel meilleur choix pour apprendre la programmation qu'un langage moderne et élégant tel que Python, aussi bon pour le développement d'applications web que pour la réalisation de scripts système ou l'analyse de fichiers textuels ? Un support de cours réputé et adopté par de nombreux enseignants, avec 40 pages d'exercices corrigés Reconnu et utilisé par les enseignants de nombreuses écoles et IUT, complété d'exercices accompagnés de leurs corrigés, cet ouvrage original et érudit est une référence sur tous les fondamentaux de la programmation : choix d'une structure de données, paramétrage, modularité, orientation objet et héritage, conception d'interface, multithreading et gestion d'événements, protocoles de communication et gestion réseau, formulaires web et (GI, bases de données) jusqu'à la désormais indispensable norme Unicode (le format UTF-8).

Diagnostic tardif d'une hyperoxalurie primitive au stade d'insuffisance rénale chronique terminale avec hypoparathyroïdie sévère

Science.gov (United States)

El Ghali, Zineb; Lahcen, Zineb Ait; Fadili, Wafaa; Kaitouni, Abderrahim Idrissi; Hakkou, Mohamed; Hamdaoui, Abderrachid; Laouad, Inass

2014-01-01

L'hyperoxalurie primitive est une anomalie métabolique congénitale rare caractérisée par un excès de production avec accumulation d'oxalate secondaire à un déficit enzymatique hépatique. Nous rapportons le cas d'un patient de 18 ans qui avait comme antécédent des lithiases rénales récidivantes depuis l'enfance évoluant vers l'insuffisance rénale chronique terminale, mis en hémodialyse périodique depuis 4 ans avec apparition d'une anémie résistante à l’érythropoïétine pour laquelle il a été multitransfusé et qui était admis pour prise en charge de douleurs osseuses invalidantes d'aggravation progressive associées à un syndrome tumoral fait d'adénopathies périphériques et de splénomégalie avec dyspnée et altération de l’état général. Le bilan réalisé avait objectivé de multiples images lytiques lacunaires et condensantes au niveau des poignets et des mains avec des petits reins calcifiés, une pleurésie avec péricardite de grande abondance drainée, une ascite de moyenne abondance avec splénomégalie homogène, une anémie normochrome normocytaire à 7.2 g/dl avec hyperferritinémie à 1129 μg/l et un syndrome inflammatoire biologique. La calcémie était spontanément normale à 97 mg/l avec hyperphosphorémie à 83 mg/l et hypoparathyroïdie à 74,85 pg/ml. Les PAL étaient à 136 UI/l, l'aluminium sérique à 13μg/l et la Vitamine D native à 20,87ng/ml. Le diagnostic d'hyperoxalurie a été retenu sur les données de la biopsie ostéomédullaire objectivant des dépôts de cristaux d'oxalate de calcium avec fibrose médullaire et réaction macrophagique à corps étranger. L’évolution a été marquée par la survenue de fractures spontanées récidivantes au niveau de l’épaule et des 2 hanches. PMID:25328593

Comparaison des conduites discursives de mères et d’enseignants dans la co-construction de récits avec des enfants

Directory of Open Access Journals (Sweden)

Vinel Elise

2014-07-01

Full Text Available Cette communication s’intéresse aux conduites discursives produites par des mères et des enseignants au cours de deux lectures conjointes d’album avec des enfants. Elle s’inscrit dans une approche dialogique et interactionniste du langage. Dans la suite des travaux de Florin (1991, Grossmann (1996, analysant les styles d’interaction des enseignants et de réception des enfants en cours de lecture, mais aussi de ceux de Vygotski (1984, Bruner (1994 ou encore Salazar Orvig et De Weck (2014, nous cherchons à comprendre de quelles manières les adultes racontent des histoires aux enfants et à quelles expériences spécifiques des récits ceux-ci sont confrontés. Dix enfants âgés de 3 à 5 ans ont été filmés au cours de ces séances de lectures d’albums, sans texte et avec texte, avec un de leur parent à leur domicile et avec des pairs et des enseignants à l’école.

Valse avec Bachir, récit d’une mémoire effacée

Directory of Open Access Journals (Sweden)

Fanny Lautissier

2009-12-01

Full Text Available Le long-métrage d’animation Valse avec Bachir (86’, 2008, du réalisateur israélien Ari Folman est un récit semi-biographique qui revient sur une expérience individuelle de la guerre du Liban et du massacre de Sabra et Chatila. Dans son inscription entre documentaire et fiction, Valse avec Bachir donne à voir un processus qui relie, à travers l’animation, une mémoire effacée, ne se résolvant pas par l’archive, à une histoire reconstruite et figurée. Les axes de réflexion mis en valeur pour mener cette étude sont la fusion des codes du documentaire et de la fiction, les modalités du récit d’un traumatisme et l’imbrication des contextes mémoriels et historiques liés à la guerre.

Communication progressive du français avec 320 exercices : niveau débutant

CERN Document Server

Miquel, Claire

2013-01-01

Ce qui fait le succès de cete ouvrage de communication: Une organisation claire: la leçon sur la page de gauche; les exercices et les activités communicatives sur la page de droite 40 fiches présentant les points généralement abordés au niveau A1 du Cadre européen commun de référence pour les langues Un apprentissage progressif: il suit la progression naturelle des méthodes de français Un usage souple: pour la classe ou en auto-apprentissage Une préparation adaptée aux certifications: un entrainement efficace pour mieux réussir aux examens A découvrir dans cette deuxième édition revue et augmentée: Un CD audio avec 69 documents sonores Un test d'évaluation avec ses corrigés Des illustrations pédagogiques acutelles et colorées 50 nouveaux exercices. Un livret de corrigés est proposé à part (ISBN 978-209-038133-7).

Stratégies fondées sur les citoyens - collaboration avec les ...

International Development Research Centre (IDRC) Digital Library (Canada)

Dans le cadre de ce projet, on cherchera à comprendre le climat d'insécurité au sein des collectivités touchées par la violence à Medellín, en Colombie, du point de vue de ceux qui le vivent (les populations vulnérables). Travaillant de concert avec des membres de la collectivité, les chercheurs relèveront les principaux ...

Cold pearl surfactant-based blends.

Science.gov (United States)

Crombie, R L

1997-10-01

Pearlizing agents have been used for many years in cosmetic formulations to add a pearlescent effect. Cold pearl surfactant-based blends are mixtures of glycol stearates and surfactants which can be blended in the cold into a wide range of personal-care formulations to create a pearlescent lustre effect. Under controlled manufacturing conditions constant viscosities and crystalline characteristics can be obtained. The development of these blends has been driven by efforts to improve the economics of adding solid pearlizing agents directly into a hot mix formulation. This paper summarizes the history of pearlizers, describes their advantages and physical chemistry of the manufacturing process. Finally some suggestions for applications are given. Les agents nacrants sont utilises depuis de nombreuses annees dans les formulations cosmetiques pour ajouter un effet nacre. Les melanges a froid a base de tensioactif nacre sont des melanges de stearates de glycol et de tensioactifs qui peuvent etre melanges a froid dans une large gamme de formulations d'hygiene personnelle pour creer un effet de lustre nacre. On peut obtenir des viscosites et des proprietes cristallines constantes avec des conditions de fabrication maitrisees. Le developpement de ces melanges a ete porte par les efforts pour ameliorer les couts de l'ajout d'agents nacrants solides directement dans une formulation melangee de l'ajout d'agents nacrants solides directement dans une formulation melangee a chaud. Cet article resume l'histoire des agents nacrants, decrit leurs avantages et al physico-chimie du procede de fabrication. On emet a la fin cetaines suggestions d'applications.

Soudage des aciers pour application mécanique

CERN Document Server

Deveaux, Dominique

2016-01-01

Ce guide détermine les bonnes pratiques pour comprendre les risques d’une forme d’assemblage multimatériaux : celui par soudage de nuances à forte teneur en carbone avec des éléments en acier de construction. Dans un premier temps, le rapport passe en revue l’examen des avaries sur des assemblages soudés pour l’application mécanique mettant en cause les aciers. Fissuration par fatigue, rupture fragile, rupture ductile, fissuration à chaud ou à froid sont autant de causes qui seront analysées. Dans un deuxième temps, il se concentre sur la conception des joints soudés. Du choix des nuances à la tenue vis-à-vis de la rupture fragile en passant par l’analyse en fatigue des assemblages soudés, c’est l’ensemble de la problématique qui est pris en compte.

Contribution to the study of isotopic exchange of oxygen between nickel oxide and the gases arising from the oxidation reaction of carbon monoxide; Contribution a l'etude de l'echange isotopique de l'oxygene entre l'oxyde de nickel et les gaz de la reaction d'oxydation de l'oxyde de carbone

Energy Technology Data Exchange (ETDEWEB)

Bailly, J C [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1967-12-01

The 3 isotopic reactions of oxygen: C{sup 18}O + Ni{sup 16}O {r_reversible} C{sup 16}O + Ni{sup 18}O, {sup 16}O{sup 18}O + Ni{sup 16}O {r_reversible} {sup 16}O{sub 2} + Ni{sup 18}O, and C{sup 16}O{sup 18}O + Ni{sup 16}O {r_reversible} C{sup 16}O{sub 2} + Ni{sup 18}O between CO, CO{sub 2}, O{sub 2} and NiO are studied using a mass spectrometer. The isotopic gaseous mixtures are prepared from oxygen-18 enriched water. A first order kinetic law has been found for these reactions in the gaseous phase, and the activation energies have been determined. Only CO and CO{sub 2} exchange oxygen, at room temperature, but only with part of the oxide surface. Gaseous O{sub 2} reacts with the whole surface at 250 C, the slow step of the exchange process, in the gaseous phase, being certainly the mobility of oxygen ions on the surface of NiO. (author) [French] Les 3 reactions d'echange isotopique de l'oxygene: C{sup 18}O + Ni{sup 16}O {r_reversible} C{sup 16}O + Ni{sup 18}O, {sup 16}O{sup 18}O + Ni{sup 16}O {r_reversible} {sup 16}O{sub 2} + Ni{sup 18}O, et C{sup 16}O{sup 18}O + Ni{sup 16}O {r_reversible} C{sup 16}O{sub 2} + Ni{sup 18}O entre l'oxyde de carbone, l'oxygene gazeux, le gaz carbonique et l'oxyde de nickel sont etudiees par spectrometrie de masse. Les melanges isotopiques gazeux sont prepares a partir d'une eau enrichie en isotope 18 de l'oxygene. Une loi cinetique du premier ordre a ete trouvee pour les trois reactions d'echange en phase gazeuse, et des energies d'activation de ces reactions ont ete determinees. Seuls CO et CO{sub 2} echangent l'oxygene, des la temperature ambiante, mais avec une fraction seulement de la surface de l'oxyde. O{sub 2} gazeux reagit avec toute la surface du solide a 250 C, l'etape lente du processus d'echange en phase gazeuse etant vraisemblablement liee a la mobilite des ions oxygene superficiels de NiO. (auteur)

L'infiltration d'une dilution ideale des solutions avec epineph rine au ...

African Journals Online (AJOL)

L'auteur rapporte un procédé simplifié de dilution d'une solution anesthésique avec épinéphrine passant d'une concentration de 1/100 000 à 1/800 000 pour rechercher une hémostase locale effective sans compromettre dans l'immédiat la vitalité de la vascularisation périphérique des lambeaux cutanés levés. The author ...

Programme de soutien à l'interaction avec la sphère des politiques ...

International Development Research Centre (IDRC) Digital Library (Canada)

Programme de soutien à l'interaction avec la sphère des politiques et à la communication de l'Initiative Think tank. Les think tanks des pays en développement entendent effectuer des recherches de qualité fondées sur des données probantes pour contribuer à la résolution d'enjeux en matière de politiques dans les pays ...

Dimensionnement d’un actionneur pour organe de pilotage à entraînement direct avec redondance passive magnétique

OpenAIRE

Allias, Jean-François

2015-01-01

Ce manuscrit de thèse, intitulé " Dimensionnement d’un actionneur pour organe de pilotage à entraînement direct avec redondance passive magnétique ", s’inscrit dans un projet ANR du nom de TEMOP pour, TEchnologie Mécatronique pour Organe de Pilotage, en lien avec la société UTC Aerospace de Figeac. L’objectif de cette thèse est de développer une solution de machine électrique permettant de générer le retour d’effort actif d’un mini-manche latéral d’aéronef, dans le but d’améliorer les sensati...

Accouchées avec statut sérologique VIH inconnu à Lubumbashi, RD ...

African Journals Online (AJOL)

Introduction: Beaucoup d'enfants vivant avec le VIH ont été infectés par leurs mères. Pour prévenir la transmission verticale les femmes doivent d'abord connaître leur statut sérologique VIH .L'objectif de cette étude était de déterminer la proportion de statut VIH inconnu à la naissance et d'identifier les facteurs associés.

Tutorial de calcul poromécanique avec le logiciel Abaqus

OpenAIRE

Bonelli, S.

2011-01-01

/ Ce tutorial est destiné à apprendre à réaliser avec Abaqus, sous CAE, un calcul de poroélasticité linéaire. Il est écrit de telle sorte que quelqu'un n'ayant jamais utilisé Abaqus, mais ayant des connaissances de base en mécanique des milieux poreux d'une part, et en éléments-finis d'autre part, puisse réaliser un tel calcul en partant de zéro. Toutefois, il ne s'agit en aucun cas d'un tutorial sur Abaqus ui-même, ni sur la méthode des éléments-finis.

Energie du type Ginzburg-Landau avec un terme de chevillage

OpenAIRE

AMARI, Nassima

2010-01-01

L’objectif de ce travail est l’étude d’un modèle bidimensionnel de Ginzburg-Landau avec un problème de l’ancrage (pinning) des vortex. La principale difficulté en réitérant l’approche faite par F. Béthuel, H. Brézis et F. Hélein, résulte du fait que la construction de mauvais disques ne soit pas évidente. Pour surmonter cette difficulté,on remplace le minimiseur u epsilon par v epsilon U epsilon. Cette substitution nous conduit à l'étude d'une énergie classique (qui correspond à p=1). ...

Mise au point du rheometre a cisaillement annulaire pour l'etude de rheologie d'un mastic bitumineux avec verre incorpore =

Science.gov (United States)

El Mansouri, Souleimane

Dans le domaine viscoelastique lineaire (VEL, domaine des petites deformations), le comportement thermomecanique du bitume et du mastic bitumineux (melange uniforme de bitume et de fillers) a ete caracterise au Laboratoire des Chaussees et Materiaux Bitumineux (LCMB) de l'Ecole de technologie superieure (ETS) avec l'appui de nos partenaires externes : la Societe des Alcools du Quebec (SAQ) et Eco Entreprises Quebec (EEQ). Les proprietes rheologiques des bitumes et des mastics ont ete mesurees grâce a un nouvel outil d'investigation appele, Rheometre a Cisaillement Annulaire (RCA), sous differentes conditions de chargement. Cet appareil permet non seulement de solliciter des eprouvettes de tailles importantes par rapport a celles utilisees lors des essais classiques, mais aussi d'effectuer des essais en conditions quasi-homogenes, ce qui permet de donner acces a la loi de comportement des materiaux. Les essais sont realises sur une large gamme de temperatures et de frequences (de -15 °C a 45°C et de 0,03Hz a 10 Hz). Cette etude a ete menee principalement pour comparer le comportement d'un bitume avec celui d'un mastic bitumineux dans le domaine des petites deformations. neanmoins, dans une seconde perspective, on s'interesse a l'influence des fillers de verre de post-consommation sur le comportement d'un mastic a faibles niveaux de deformations en comparant l'evolution des modules complexes de cisaillements (G*) d'un mastic avec fillers de verre et un mastic avec fillers conventionnels (calcaire). Enfin, le modele analogique 2S2P1D est utilise pour simuler le comportement viscoelastique lineaire des bitumes et des mastics bitumineux testes lors de la campagne experimentale.

On the Optimal Thermal Management of Hybrid-Electric Vehicles with Heat Recovery Systems Sur le thermo-management optimal d’un véhicule électrique hybride avec un système de récupération de chaleur

Directory of Open Access Journals (Sweden)

Merz F.

2012-09-01

Full Text Available A general framework to combine optimal energy management (powertrain supervisory control and thermal management in Hybrid Electric Vehicles (HEV is presented. A HEV system with engine exhaust aftertreatment and exhaust heat recovery system is simulated under various scenarios, including warm and cold start. Optimal strategies are derived from Pontryagin Minimum Principle (PMP. The concept of fuel equivalent of thermal energy variations – similar to the equivalence factors for battery energy of standard Equivalent Consumption Minimization Strategy (ECMS – is introduced. The PMP-based strategies are compared with a heuristic, rule-based strategy. The benefits in fuel economy and reduction of pollutant emissions that are obtained for several scenarios are very promising. Une approche généralisée pour combiner la gestion de l’énergie (supervision du groupe motopropulseur et le thermo-management dans les véhicules hybrides électriques est proposée. Un système hybride incluant le post-traitement des polluants et un système de récupération de la chaleur à l’échappement du moteur thermique est simulé pour plusieurs scénarii, y compris le cas de départ à froid. Des stratégies de gestion de l’énergie optimales sont dérivées à partir du Principe de Minimum de Pontriaguine (PMP. Inspirée par les facteurs d’équivalence pour la consommation électrique que l’on retrouve dans la stratégie ECMS, la notion d’équivalent en carburant des flux d’énergie thermique est introduite. Les stratégies dérivées du PMP sont comparées avec une stratégie heuristique basée sur des règles. Les bénéfices en termes d’économies de carburant et réduction des émissions polluantes que l’on trouve pour différents scénarii sont encourageantes.

Grammaire progressive du français niveau intermédiaire : avec 680 exercices

CERN Document Server

Grégoire, Maïa

2013-01-01

Une organisation claire : la leçon de grammaire sur la page de gauche ; les exercices d'entraînement sur la page de droite ; 52 chapitres présentant les points généralement abordés aux niveaux A2 et B1 du Cadre européen commun de référence pour les langues ; Un apprentissage progressif : il suit la progression naturelle des méthodes de français ; Un usage souple : pour la classe ou en auto-apprentissage ; Une préparation adaptée aux certifications : un entraînement efficace pour mieux réussir aux examens ; Une large place faite à l'évaluation : de nombreux exercices de révision et des bilans réguliers. À découvrir dans cette troisième édition tout en couleurs : Un CD audio avec 14 documents sonores ; 80 nouveaux exercices et activités communicatives ; Des chapitres révisés et des exercices plus variés ; Un test d'évaluation avec ses corrigés ; Et... un livre web, 100% en ligne, inclus. Cet ouvrage contient un code d'activation donnant gratuitement accès sur http://livre-web.com...

Orienteering Club

CERN Multimedia

Club d'orientation

2013-01-01

Course d'orientation Le coup d’envoi de la coupe genevoise a été donné samedi 31 août dans les bois de Combe Froide à Prémanon. Plus de 150 coureurs avaient fait le déplacement. Les parcours facile court, facile moyen et technique court ont été remportés par des coureurs du club O’Jura - Ulysse Dannecker, Léo Lonchampt, Franck Lonchampt, le technique moyen par Pekka Marti du club Ol Biel Seeland et le technique long par Térence Risse du CA Rosé – également membre de l’équipe nationale suisse des moins de 20 ans. Pour le club du CERN, les meilleures résultats ont été obtenus pas Emese Szunyog sur technique court et Marie Vuitton sur technique moyen avec une 4e place. La prochaine course aura lieu samedi 14 septembre à La Faucille. Le club propose aussi...

Theatre

CERN Multimedia

Théâtre les 50

2010-01-01

MARIONNETTES Compagnie Stella Rossa   Dimanche 12 décembre à 15h et 17h Costanza Solari vient enchanter les grands et les petits à partir de 3 ans avec 4 histoires   Séance de 15 heures : « Une histoire de feu, une histoire de chaleur, une histoire de dragon » Il faut vite faire quelque chose pour réchauffer une grand-mère qui a froid. Après avoir tout essayé, la seule solution pour Mia sera de trouver un dragon qui veuille bien lui céder un peu de son feu… « La princesse et la balle d’or » Il arriva que la balle d’or, au lieu de revenir dans sa main, tomba sur le sol et roula tout droit dans l’eau. La princesse la suivit des yeux, mais la balle disparut : la fontaine était si profonde qu’on n’en voyait pas le fond… Séance de 17 heures : « N...

Afrique occidentale et centrale — De nouveaux défis relevés avec ...

International Development Research Centre (IDRC) Digital Library (Canada)

25 janv. 2011 ... Ainsi, les éleveurs de l'Afrique occidentale et centrale doivent composer avec un certain nombre de changements écologiques et sociaux, tels que la vente de pâturages à des agriculteurs. La privatisation de superficies qui étaient jusque-là réservées à la vaine pâture occasionne souvent des problèmes ...

Prédictions bayésiennes de statistiques d'ordre Avec des données ...

African Journals Online (AJOL)

intéresse à la prédiction de statistiques d'ordre et de fonctions de celles-ci sur un échantillon futur de taille N, issu de la même loi et indépendant de l'échantillon observé. L'approche utilisée est une approche bayésienne avec une loi a priori ...

Experimental study of an ion cyclotron instability in a magnetic well confined plasma; Etude experimentale d'une instabilite cyclotronique ionique dans un plasma confine dans un puits magnetique

Energy Technology Data Exchange (ETDEWEB)

Brossier, P [Commissariat a l' Energie Atomique, Fontenay-Aux-Roses (France). Centre d' Etudes Nucleaires

1969-07-01

This report is a contribution to the study of microinstabilities in macroscopically stable plasmas, in the low-{beta} limit. Ion cyclotron instabilities, with k{sub ||} = 0, have been numerically studied in detail; the computation of the density thresholds and growth rates of the different harmonics showed the relative role played by the following energy sources: density gradient, perpendicular distribution function and cold plasma component. This theoretical model has been compared with the results of a detailed study (density thresholds, wave structure, frequency spectrum, wavelengths, growth rate, amplitude of the electric field) of the instability observed in the DECA II device. This comparison gave a good agreement which shows the destabilising role played by the cold plasma component on a hot plasma with a loss cone distribution function. (author) [French] Ce rapport est une contribution a l'etude des microinstabilites dans les plasmas macroscopiquement stables, dans la limite des {beta} << 1. Les instabilites cyclotroniques ioniques, a k{sub ||} = 0, ont ete etudiees numeriquement en detail; le calcul des seuils de densite et taux de croissance des differents harmoniques a permis de preciser l'importance relative des facteurs destabilisants suivants: gradient de densite, fonction de distribution perpendiculaire, presence de plasma froid. Ce modele theorique a ete confronte avec les resultats d'une etude detaillee (seuils de densite, structure de l'onde, spectres de frequence, longueurs d'onde, taux de croissance, amplitude du champ electrique) de l'instabilite observee dans l'experience DECA II, Cette confrontation aboutit a un accord satisfaisant qui montre le role destabilisant joue par le plasma froid sur un plasma chaud presentant une distribution de cone de pertes. (auteur)

Study of some continuous spectra produced by nuclear reactions with light nuclei; Etude de quelques spectres continus produits par reactions nucleaires avec des noyaux legers

Energy Technology Data Exchange (ETDEWEB)

Marquez, L

1966-07-01

The continuous spectra coming from several nuclear reactions with light nuclei were measured. The spectra can be explained by a two-step reaction mechanism; however, the reactions produced by {sup 6}Li are different. A mechanism was proposed to explain their spectra based on the following assumptions: {sup 6}Li makes a nuclear molecule with the target which subsequently breaks up in such a way that an {alpha} particle comes out with the kinetic energy that it has in the molecule. The calculated spectra and those measured are in good agreement. (author) [French] Nous avons mesure les spectres continus produits dans plusieurs reactions nucleaires avec des noyaux legers. A l'exception des spectres produits par {sup 6}Li, on a trouve qu'on pouvait expliquer ces spectres par le mecanisme des reactions en deux etapes. Nous avons propose un mecanisme pour expliquer les spectres produits par {sup 6}Li. On suppose que {sup 6}Li forme une molecule nucleaire avec la cible qui eclate ensuite de facon telle qu'une particule alpha de la molecule sort avec l'energie cinetique de son mouvement propre dans la molecule. Les spectres calcules avec ces hypotheses et les spectres mesures sont en bon accord. (auteur)

Communication progressive du français avec 320 exercices : niveau débutant : corrigés

CERN Document Server

Miquel, Claire

2013-01-01

Ce qui fait le succès de cet ouvrage de communication: Une organisation claire: la leçon sur la page de gauche; les exercices et les activités communicatives sur la page de droite 40 fiches présentant les points généralement abordés au niveau A1 du Cadre européen commun de référence pour les langues Un apprentissage progressif: il suit la progression naturelle des méthodes de français Un usage souple: pour la classe ou en auto-apprentissage Une préparation adaptée aux certifications: un entrainement efficace pour mieux réussir aux examens A découvrir dans cette deuxième édition revue et augmentée: Un CD audio avec 69 documents sonores Un test d'évaluation avec ses corrigés Des illustrations pédagogiques acutelles et colorées 50 nouveaux exercices. Communication Progressive du français niveau débutant, 2ème édition (ISBN 978-209-038132-0).

L’utilisation de l’approche CTC: quel impact sur la couverture vaccinale lors de la campagne préventive de vaccination contre la méningite A avec le MenAfriVac au Togo en 2014?

Science.gov (United States)

Landoh, Dadja Essoya; Kahn, Anna-Léa; Lacle, Anani; Adjeoda, Kodjovi; Saka, Bayaki; Yaya, Issifou; Nassoury, Danladi Ibrahim; Kalao, Assima; Makawa, Makawa-Sy; Biey, Nsiari-Mueyi Joseph; Bita, Andre; Toke, Yaovi Temfa; Dörte, Petit; Imboua, Lucile; Ronveaux, Olivier

2017-01-01

ésultats de cette enquête montrent que l'utilisation de la CTC dans un pays à ressources limitées comme le Togo n'a pas eu un effet négatif sur les couvertures vaccinales. En effet, il n'y avait pas de différence entre la couverture vaccinale dans les zones CTC et celles non CTC. Il importe de capitaliser l'expérience acquise pour l'utilisation des vaccins du Programme Elargi de Vaccination avec l'approche CTC surtout dans les pays à ressources limitées confrontés à la disponibilité de la chaîne de froid. Background A vaccination campaign against meningitis A using MenAfriVac vaccine was implemented in the four regions of northern Togo from 28 November to 7 December 2014. CTC approach was first used on a large scale in a vaccination campaign in ten health districts in Togo. This study aims to estimate the immunization coverage and to determine the effect of Controlled Temperature Chain (CTC) approach on these immunization coverages. PMID:28761614

Le système de l'harmonie de Rameau dans sa correspondance avec d'Alembert et Rousseau

Directory of Open Access Journals (Sweden)

Stefanović Ana M.

2002-01-01

Full Text Available (francuski L'article examine la correspondance polémique de Rameau avec d'Alembert et Rousseau, entretenue dans la sixième décénie du XVIIIe siècle. Le système de l'harmonie de Rameau y est affronté à deux défis contradictoires: d'un côté, à la provocation d'absolutisation du système venant de son intériorité-même, et de l'autre, à une nouvelle conception de l'autonomie musicale, conçue sur le geste anarchique et destructif envers lui. Tandis que, de la polémique avec d'Alembert, le système vient de ressortir assuré et renforcé, soutenant la suprématie de la musique dans le champ théorique, la polémique avec Rousseau démontre que l'autonomie scientifique n'entraîne pas de soi l'isolation de la musique dans le domaine esthétique. Fondé sur le réseau cohérent de ses propres règles, le système musical est apte de se plier, de se modifier sous l'influence de ce qui lui est "extérieur": du sens contenu dans des énoncés linguistiques. L'idée de représentation musicale est alors modifiée dans la direction d'une réconcilliation possible de la raison (cartésienne et de l'imagination créatrice, du général et du particulier, de la norme et de l'individualité, dans la mesure où le système musical devenant analogue au système linguistique, en tant que "langue en action" participe chaque fois dans l'événement de sa propre création.

Créer avec SketchUp 16 projets, de l'architecture au théâtre

CERN Document Server

2009-01-01

Grâce à SketchUp, la 3D n'est plus l'apanage des seuls programmes de CAO spécialisés. Plus besoin d investir des milliers d euros en logiciels et en matériel informatique haut de gamme ! Les concepteurs comme le grand public disposent maintenant d un outil efficace, rapide et intuitif pour modéliser en trois dimensions le fruit de leur imagination. Cet ouvrage, à l'approche originale et concrète, vous dispense des conseils pour acquérir de bonnes pratiques d'utilisation de SketchUp, manier ses fonctions avancées et le faire collaborer avec d'autres logiciels. Il présente un tour d horizon de SketchUp et 16 cas d'utilisation professionnelle réels, couvrant une vaste gamme de métiers, de l'architecture à la menuiserie en passant par le graphisme, la scénographie, la géologie, l'ingénierie ou l'infographie. Chaque auteur partage avec vous ses méthodes et astuces, issues de sa pratique professionnelle, qui vous permettront de gagner du temps et de dépasser les limites apparentes parfois rencon...

Reflexions sur l' origine du passif forme avec venire

Directory of Open Access Journals (Sweden)

M. Regula

1958-12-01

Full Text Available Le but que nous nous sommes proposé dans cette étude, est assez modeste: Il s'agit de combler une lacune de la réfutation des raisons alléguées par K. v. Ettmayer contre venire + participe passé comme base primaire du passif1 et d'expliquer l'origine de cette formule. Dans la ZRPh XLI, 42 ss., K. v. Ettmayer a fait les hypothèses suivantes: venitur ereptum puellam > *venit ereptum puellam > puella venit erepta. Cette dérivation de la périphrase verbale du passif nous paraît trop scrupuleuse et diffuse. On sait que ce savant a fait deux objections contre l'explication la plus naturelle de la formation du passif avec venire . La première, c'est que la séquence venire + p. p. ne pouvait être attesté par le latin. Mais, voici des exemples qui servent de contreargument.

Vérification de programmes OCaml fortement impératifs avec Why3

OpenAIRE

Filliâtre , Jean-Christophe; Pereira , Mário; Melo De Sousa , Simão

2018-01-01

International audience; Cet article présente une méthodologie pour prouver des programmes OCaml fortement impératifs avec l'outil de vérification déductive Why3. Pour un programme OCaml donné, un modèle mémoire spécifique est construit et on vérifie un programme Why3 qui le mani-pule. Une fois la preuve terminée, on utilise la capacité de Why3 à traduire ses programmes vers le langage OCaml, tout en remplaçant les opérations sur le modèle mémoire par les opérations correspondantes sur des typ...

Étude expérimentale des performances thermiques d’un nanofluide: eau-éthylène-glycol-Al2O3

Directory of Open Access Journals (Sweden)

Răzvan-Silviu Luciu

2007-01-01

Full Text Available Une nouvelle classe de fluides composée par des nanoparticules métalliques en suspension dans un liquide, appelée nanofluide, est apparue récemment. Quelques études numériques et expérimentales ont montré que ces nouveaux fluides possedent une puissance d’échange thermique remarquable, comparée aux liquides conventionnels. L’étude qui suit a le bout de montrer par voie expérimentale les performances thermiques d’un nanofluide composé d’oxyde d’alumine dispersé dans de l’éthylene-glycol en différentes concentrations, allant de 0 a 2%. Le dispositif expérimental est un échangeur a tubes concentriques en inox, avec écoulement du fluide chaud dans le tube central et du fluide froid dans le tube annulaire. Les résultats obtenus montrent que la présence des nanoparticules dans le fluide de base a pour effet une augmentation considérable du transfert thermique.

Extraction, fractionnement et concentration des huiles marines

Directory of Open Access Journals (Sweden)

Linder Michel

2004-03-01

Full Text Available Les huiles marines représentent des sources potentielles d’acides gras polyinsaturés (AGPI dont les implications au niveau de la nutrition et de la santé sont avérées. Ces molécules sont extraites à partir de poissons, algues ou co-produits de la filière halieutique par des procédés de cuisson-pression, en présence de solvants ou par des techniques enzymatiques beaucoup moins drastiques. Des fractions plus ou moins purifiées en AGPI sont obtenues par cristallisation à froid, en présence de solvants organiques, complexation avec de l’urée, distillation moléculaire ou extraction par fluide supercritique. L’utilisation de lipases stéréospécifiques dans des procédés d’hydrolyse et d’estérification conduit à une diversité de molécules d’acylglycérols riches en AGPI trouvant de nombreuses applications dans le domaine de l’agroalimentaire et de la santé.

Sur les pistes de la mondialisation

Directory of Open Access Journals (Sweden)

Jean-Christophe Gay

2006-07-01

Full Text Available Premier sport olympique, l’athlétisme est un des sports les plus mondialisés, mais l’analyse des résultats complets des championnats du monde permet de constater de fortes disparités entre États. De bipolaire, au temps de la Guerre froide, la localisation de l’excellence athlétique a évolué pour devenir multipolaire, avec l’émergence de foyers remarquables, tels l’Afrique de l’Est ou le Maghreb, à côté des traditionnels foyers européen et nord-américain, berceau de ce sport. Une analyse par familles de disciplines (sprint, demi-fond et fond, lancers permet de constater des résultats très contrastés. Les grands principes de cette division du travail athlétique à l’échelle mondiale sont expliqués. La mobilité des athlètes ou le jeu des naturalisations constituent d’autres aspects de la mondialisation de l’athlétisme.

Littérature progressive du français avec 600 activités : niveau intermédiaire

CERN Document Server

Blondeau, Nicole; Né, Marie-Françoise

2004-01-01

Une organisation claire : le texte littéraire, une courte biographie de l'auteur et des notes explicatives sur la page de gauche; des activités guidées de découverte et d'exploitation sur la page de droite la progression : les textes sont classés par ordre chronologique. Les activitées de lecture et d'analyse constituent un véritable parcours d'aprentissage le choix des textes : du Moyen Age à nos jours, avec une priorité accordée à la littérature contemporaine (XIXe et XXe), des textes parmi les plus représentatifs de la littérature française, avec une ouverture sur la littérature francophone l'appareil pédagogique propose une approche facilitant la découverte et la compréhension de l'histoire littéraire, le repérage des genres et la portée des idées un usage souple : pour la classe ou en auto-apprentissage A découvrir dans cette deuxième édition revue et augmentée:

Littérature progressive du français avec 600 activités : niveau débutant

CERN Document Server

Blondeau, Nicole; Né, Marie-Françoise

2004-01-01

Une organisation claire : le texte littéraire, une courte biographie de l'auteur et des notes explicatives sur la page de gauche; des activités guidées de découverte et d'exploitation sur la page de droite la progression : les textes sont classés par ordre chronologique. Les activitées de lecture et d'analyse constituent un véritable parcours d'aprentissage le choix des textes : du Moyen Age à nos jours, avec une priorité accordée à la littérature contemporaine (XIXe et XXe), des textes parmi les plus représentatifs de la littérature française, avec une ouverture sur la littérature francophone l'appareil pédagogique propose une approche facilitant la découverte et la compréhension de l'histoire littéraire, le repérage des genres et la portée des idées un usage souple : pour la classe ou en auto-apprentissage A découvrir dans cette deuxième édition revue et augmentée:

Apprivoiser le conte: notes sur un atelier en langue seconde avec la conteuse professionnelle, Stéphanie Bénéteau

Directory of Open Access Journals (Sweden)

Stéphanie Nutting

2015-06-01

Full Text Available Voici un compte rendu de l'atelier avec la conteuse professionnelle, Stéphanie Bénéteau. Organisé pour un groupe d'étudiants de niveau universitaire, l'atelier avait pour but d'initier les étudiants à une technique qui permet de se souvenir d'un conte sans le mémoriser. Le compte rendu est émaillé de propos recueillis lors d'un entretien avec Bénéteau réalisé en 2014. Ce texte a deux objectifs: 1-fournir des outils qui permettront aux lecteurs de mettre en pratique la méthode proposée par Bénéteau 2-fournir des observations spécifiques sur le rôle de l'improvisation dans l'apprentissage du conte en situation de français, langue étrangère.

« Faire clair et vif avec des éléments complexes »

Directory of Open Access Journals (Sweden)

Cordula Reichart

2010-12-01

Full Text Available Avec le roman Salammbô et le conte Hérodias, Flaubert se tourne vers l’Antiquité préchrétienne afin de montrer à la modernité, sur le mode « clair et vif », sa complexité, son implication dans des discours de pouvoir religieux et historiographiques. C’est en se penchant sur les sources historiographiques et bibliques que Flaubert décline les stratégies d’exclusion et de surécriture, mettant au jour ce qu’elles refoulent, non pas sous forme de signification alternative, explicite, mais en tant que défiguration, réalisation littérale des corps et des signes.Avec Salammbô, Flaubert écrit une histoire du salut. Carthage, représentée dès le début par la protagoniste Salammbô en tant que pars pro toto, expose les figures cachées de Rome, à laquelle est liée, aussi et surtout, la promesse chrétienne de salut. Dans le nom de Salammbô Flaubert réécrit l’origine de cette figure en fait associée à la Rome chrétienne en s’appuyant sur l’exemple de l’histoire antique de Carthage.Dans Hérodias, Flaubert reprend le thème du triomphe de l’Orient annoncé par Renan et redouté par l’Église catholique. Un danger, pourrait-on dire, qui se réalise dans la figure d’Hérodias et qui est conjuré avec la décapitation de Jean. Dans son rapport inversé avec les textes de référence, Hérodias démasque les ambitions et la volonté hégémonique du modèle de pouvoir propre à l’Église en Orient. La translatio de l’empire romain est radicalisée au moyen de la figure d’Aulus. Aulus peut faire l’objet d’une lecture performative en tant que début et fondement de l’histoire française du salut comme histoire romaine de la perversion.In the novel Salammbô and the short story Hérodias, Flaubert turns to pre-Christian antiquity in order to present modernity its complexity, its entwinement in religious and historiographical discourses of power, in a « clair et vif » manner. In Salammb

A phenomenon of direct conversion of ionizing energy resulting from the formation of negative droplets by electron capture during condensation of a vapour even without electronic affinity; Sur un phenomene de conversion directe d'energie ionisante resultant de la formation de gouttelettes negatives par capture d'electrons, lors de la condensation d'une vapeur, meme sans affinite electronique

Energy Technology Data Exchange (ETDEWEB)

Kraux, P [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1969-06-01

An electromotive force is produced between a cold and a hot electrode immersed in an ionized vapour. It is shown that the dissymmetry thus created consists in the formation of heavy, negative charge carriers following the condensation of the vapour in the volume close to the cold electrode. The electromotive forces produced are explained on the basis of a decrease in the floating potential of the cold electrode. (author) [French] Une force electromotrice apparaissant entre une electrode chaude et une electrode froide plongees dans une vapeur ionisee, on etablit que la disymetrie ainsi causee consiste en la formation de porteurs de charge negatifs lourds consecutive a la condensation de la vapeur en volume pres de l'electrode froide. On justifie les forces electromotrices observees par la diminution du potentiel flottant de l'electrode froide. (auteur)

Enfants conçus avec une aide médicale dans la cohorte Elfe

OpenAIRE

Poulalhon, Claire

2015-01-01

Objectif : étudier les conditions entourant la naissance des enfants conçus avec une aide médicale, et explorer le rôle des facteurs sociaux et médicaux dans la prématurité et l’hypotrophie.Méthodes : l'analyse porte sur 9495 enfants de la cohorte Elfe, de terme supérieur à 33 semaines d'aménorrhée, singletons ou jumeaux, répartis en trois groupes selon leur contexte de conception, "traitement", "infertiles non traités" et "fertiles" (790, 1044 et 7661 enfants). Cinq champs ont été décrits (c...

Study of thermodynamic properties of binary and ternary liquid alloys of aluminium with the elements iron, cobalt, nickel and oxygen; Etude des proprietes thermodynamiques des alliages liquides binaires et ternaires de l'aluminium avec les elements fer, cobalt, nickel et l'oxygene

Energy Technology Data Exchange (ETDEWEB)

Vachet, F [CEA Vallee du Rhone, 26-Pierrelatte (France)

1966-07-01

The present work deals with the thermodynamic study of aluminium liquid alloys with the metals iron, cobalt and nickel. The experiments carried out lead to the activity, at 1600 deg C, of aluminium in the (Al, Fe), (Al, Co), (Al, Ni) liquid alloys. The experimental method used consists in studying the partition of aluminium between the liquid immiscible phases made up with the pairs of metals (Fe, Ag), (Co, Ag), (Ni, Ag). The informations so obtained are used for drawing the isothermal equilibrium phases diagrams sections of (Al, Fe, Ag), (Al, Co, Ag), (Al, Ni, Ag) systems. The study of the partition of silver between lead and aluminium joined with the determinations of several authors allows us to determine the aluminium activity, analytically presented, in the metal M (iron cobalt and nickel). The Wagner's interaction parameters of aluminium in metal M are determined. The results obtained as the equilibrium phases diagrams of (Al, M) systems allow to compare the thermodynamic properties of the Al Fe system in liquid and solid states and to estimate the enthalpies of melting of the AlCo and AlNi intermetallic compounds. The activity, at 1600 deg C, of aluminium in (Al, Fe, Co), (Al, Fe, Ni), (Al, Co, Ni) liquid alloys is estimated through thermodynamic properties of binary components systems by application of several methods leading to results in good agreement. The study of aluminium-oxygen interactions in the liquid metallic solvants M allows us to propose an explanation for the shape of the deoxidation equilibrium line of iron, cobalt and nickel by aluminium and to compare the de-oxidizing power of aluminium toward iron, cobalt and nickel oxides. (author) [French] Le travail presente se rapporte a l'etude thermodynamique des alliages liquides de l'aluminium avec les metaux fer, cobalt et nickel. Les experiences effectuees ont pour but de determiner l'activite, a 1600 C, de l'aluminium dans les alliages liquides (Al, Fe), (Al, Co), (Al, Ni). La methode

Angiomyolipome rénal agressif avec extension à la veine rénale: à propos d'un cas et une revue de la littérature

Science.gov (United States)

Majdoub, Aziz El; Khallouk, Abdelhak; Farih, Moulay Hassan

2017-01-01

L'angiomyolipome rénal est une tumeur qui est reconnue bénigne. Elle présente trois composantes différentes: musculaire, vasculaire et graisseuse, dont la distribution est variable. Le diagnostic repose sur la mise en évidence de la composante graisseuse intra-tumorale en TDM ou IRM. Exceptionnellement la tumeur peut avoir un caractère agressive avec extension locorégionale et veineuse (la veine rénale et la veine cave inferieure). Nous présentons une observation d'une patiente âgée de 37 ans présentant un Angiomyolipome rénal volumineux avec extension à la veine rénale. PMID:29599888

Recording {gamma} spectrometer with elimination of compton background; Spectrographe {gamma} enregistreur avec elimination du bruit de fond compton

Energy Technology Data Exchange (ETDEWEB)

Julliot, C [Commissariat a l' Energie Atomique, Saclay (France).Centre d' Etudes Nucleaires

1960-07-01

This instrument, derived from the recording {gamma} spectrograph, gives better definition of photoelectric peaks by elimination of pulses caused by {gamma} photons incompletely absorbed in the scintillator (Compton effect). This system uses an original method devised by Peirson: the spectrum, devoid of photoelectric peak, supplied by a detector equipped with an anthracene scintillator, is cut off from the spectrum provided by a conventional detector equipped with a Nal (T1) scintillator. The regulation of the mechanical system, detector support and source allows the detection yields to be adjusted. The electronic system is identical in presentation with that of the recording spectrograph. (author) [French] Cet appareil derive du spectrographe {gamma} enregistreur permet d'obtenir une meilleure definition des pics photoelectriques, par elimination des impulsions provenant des photons {gamma} incompletement absorbes dans le scintillateur (effet Compton). Cet ensemble met en oeuvre une methode originale due a Peirson: le spectre, depourvu de pic photoelectrique, fourni par un detecteur, equipe avec un scintillateur d'anthracene, est retranche du spectre donne par un detecteur classique, equipe avec un scintillateur de NaI (T1). Le reglage de l'ensemble mecanique, support des detecteurs et de la source, permet d'ajuster les rendements de detection. L'ensemble electronique se presente sous un aspect identique a celui du spectrographe enregistreur. (auteur)

Mesure asymétrie avant-arriere des quarks lourds a LEP1 avec le détecteur OPAL

CERN Document Server

Lafoux, H

A partir de l'ensemble des données accumulées par OPAL au cours de la première phase de fonctionnement du LEP, nous avons mesuré l'asymétrie avant-arrière des quarks b et c au voisinage du pic du Zo. Utilisant une méthode traditionnelle, basée sur la détection des leptons produits dans les désintégrations semi-leptoniques des hadrons lourds, nous avons cherché à optimiser chaque étape de la mesure, en mettant en œuvre les algorithmes les plus appropriés. Le recours aux réseaux de neurones artificiels s'est en particulier avéré d'une grande utilité lorsque le problème à résoudre impliquait la prise en compte simultanée de multiples sources d'informations, d'origine et de nature très variées. Nos résultats sont en bon accord avec ceux des autres mesures effectuées à LEP et compatibles avec les prédictions du Modèle Standard pour un quark top de 174 ± 31 GeV/c2 et un boson de Higgs de masse comprise entre 60 et 1000 GeV/c2

Fluctuations Magnetiques des Gaz D'electrons Bidimensionnels: Application AU Compose Supraconducteur LANTHANE(2-X) Strontium(x) Cuivre OXYGENE(4)

Science.gov (United States)

Benard, Pierre

. Il est ensuite demontre que le modele a trois bandes predit les memes resultats pour la position des structures du facteur de structure magnetique que le modele a une bande, dans la limite ou l'hybridation des orbitales des atomes d'oxygene des plans Cu-O_2 et l'amplitude de sauts vers les seconds voisins sont nulles. Il est de plus constate que l'effet de l'hybridation des orbitales des atomes d'oxygene est bien modelise par le terme de saut vers les seconds voisins. Meme si ils decrivent correctement le comportement qualitatif des maximums du facteur de structure magnetique, les modeles a trois bandes et a une bande ne permettent pas d'obtenir une position de ces structures conforme avec les mesures experimentales, si on suppose que la bande est rigide, c'est-a-dire que les parametres du Hamiltonien sont independants de la concentration de strontium. Ceci peut etre cause par la dependance des parametres du Hamiltonien sur la concentration de strontium. Finalement, les resultats sont compares avec les experiences de diffusion de neutrons et les autres theories, en particulier celles de Littlewood et al. (1993) et de Q. Si et al. (1993). La comparaison avec les resultats experimentaux pour le compose de lanthane suggere que le liquide de Fermi possede une surface de Fermi disjointe, et qu'il est situe pres d'une instabilite magnetique incommensurable.

Nouvelles: KEK: B pour BELLE; NA48 mesure la violation directe de CP; LEL: le laser à électrons libres dépasse le kilowatt; Le LEP à 100 pour 100; Tour d'honneur au RHIC; Mesures de précision; Etude sur les modes de gestion du village planétaire; Conférence PANIC99 à Uppsala; Rencontre électron-noyau à HERA; LPP, Doubna célèbre une décennie; Les physiciens auscultent le photon; Aimants chauds venus du froid

CERN Multimedia

1999-01-01

Nouvelles: KEK: B pour BELLE; NA48 mesure la violation directe de CP; LEL: le laser à électrons libres dépasse le kilowatt; Le LEP à 100 pour 100; Tour d'honneur au RHIC; Mesures de précision; Etude sur les modes de gestion du village planétaire; Conférence PANIC99 à Uppsala; Rencontre électron-noyau à HERA; LPP, Doubna célèbre une décennie; Les physiciens auscultent le photon; Aimants chauds venus du froid

Advanced Technology for Aero Gas Turbine Components: Conference Proceedings Held at the Propulsion and Energetics Panel (69th) Symposium in Paris (France) on 4-8 May 1987

Science.gov (United States)

1987-09-01

Simuitaniment, Ia forte composante tangentielle de l’coulement absolu en sortie du mobile doit Otre annulbe, ce qui corres pond A une diviation de...calculs quasi-tridimensionnpls. Le essais a froid de la turbine sur le banc et len ensais correnpondants A chaud sur le turbomoteur permettent d...0.5Re 0 e 6 .10 6 (A froid ) Rapport de la vitesse p~riph~rique sur la vitesse de jet U er/V.j = 0.69 3 - PREDIMENSIONNEMENT DE LA TURBINE RADIALE

En géographie, comme en science, l'original est lié avec l'originaire

Directory of Open Access Journals (Sweden)

Iosif Daniel

2017-12-01

Full Text Available De nos jours, les scientifiques doivent garder un relativisme intellectuel, combiné avec une plus forte relation des idées. On ne doit pas s’accrocher { une définition, { une terminologie sèche. Kierkegaard disait que le désir d’éviter les définitions c’est une preuve de tact. On ne doit pas s’esquiver de créer de nouvelles dimensions et nouvelles perspectives ; et, surtout, on ne doit pas oublier que l’original provient, indubitablement, de l’originaire aussi. La revue Cinq Continents encourage de telles perspectives et représente un lieu de la liberté de la pensée géographique.

Singlet oxygen quenching by oxygen in tetraphenyl-porphyrin solutions

International Nuclear Information System (INIS)

Dedic, Roman; Korinek, Miloslav; Molnar, Alexander; Svoboda, Antonin; Hala, Jan

2006-01-01

Time-resolved measurement of singlet oxygen infrared phosphorescence is a powerful tool for determination of quantum yields and kinetics of its photosensitization. This technique was employed to investigate in detail the previously observed effect of singlet oxygen quenching by oxygen. The question whether the singlet oxygen is quenched by oxygen in ground or in excited state was addressed by study of two complementary dependencies of singlet oxygen lifetimes: on dissolved oxygen concentration and on excitation intensity. Oxygen concentration dependence study of meso-tetra(4-sulphonato)phenylporphyrin (TPPS 4 ) phosphorescence kinetics showed linearity of the dependence of TPPS 4 triplet state rate-constant. Corresponding bimolecular quenching constant of (1.5±0.1)x10 9 l/mol s was obtained. On the other hand, rate constants of singlet oxygen depopulation exhibit nonlinear dependence on oxygen concentration. Comparison of zero oxygen concentration-extrapolated value of singlet oxygen lifetime of (6.5±0.4) μs to (3.7±0.1) μs observed under air-saturated conditions indicates importance of the effect of quenching of singlet oxygen by oxygen. Upward-sloping dependencies of singlet oxygen depopulation rate-constant on excitation intensity evidence that singlet oxygen is predominantly quenched by oxygen in excited singlet state

Particules de vie conversation avec François Englert

CERN Document Server

Baré, François

2014-01-01

Ce fut l'événement de l'année 2013 : François Englert obtenait le prix Nobel de physique pour la découverte du boson. Le premier Belge à être honoré par ce prix depuis Ilya Prigogine en 1977. Françoise Baré, journaliste à la RTBF, et Guy Duplat, ingénieur civil physicien, ex-rédacteur en chef du Soir, auteur de Une vague belge (Racine) et journaliste à La Libre Belgique, ont rencontré plusieurs fois, longuement, François Englert, avant son prix et après celui-ci. Ils étaient là lors de l'annonce de la découverte du boson de BEH, lors de l'annonce du prix Nobel et, à Stockholm, lors de la remise du prix par le roi de Suède. À eux, François Englert a accepté de raconter sa chasse au boson, sa vie, ses idées. Au fil de la conversation se dessine alors le portrait attachant d'un homme brillant et libre, habité par un rêve, celui de comprendre, de décortiquer ce monde et de chercher la beauté de ses lois. Avec, en annexe, les grands points scientifiques qui éclairent le travail de F...

Les représentations du VIH, des personnes vivant avec le VIH et des soins dans les manuels en soins infirmiers : une analyse qualitative de contenu

Directory of Open Access Journals (Sweden)

Stephany Cator

2018-03-01

Full Text Available Depuis la découverte du virus, les manuels en soins infirmiers incluent la notion de VIH/sida pour qu’elle soit transmise dans la formation de premier cycle. Cependant, les écrits dévoilent l’existence d’un écart entre cette formation et les compétences requises pour prodiguer des soins aux personnes vivant avec le VIH. Conscientes des lacunes de la formation initiale en VIH/sida et qui, à ce jour, n’ont pas été explorées dans les manuels, nous avons réalisé une analyse qualitative de contenu de 18 manuels de médecine-chirurgie. Les résultats de cette étude ont dévoilé trois catégories : les représentations du VIH, des personnes vivant avec le VIH et des soins. La première catégorie renvoie à la façon dont on raconte l’histoire du VIH et parle du virus ainsi que la façon dont on décrit la maladie et conceptualise la transmission. La deuxième correspond aux personnes qui sont à risque de contracter le VIH, qui vivent avec le VIH et à la façon dont on les représente. La troisième réfère à la représentation des types de soins, leurs objectifs et les enjeux qui y sont associés.

Recovery of sludge from the treatment of liquid radioactive effluents by co-precipitation with calcium carbonate: laboratory study; Recuperation des boues de traitement des effluents radioactifs liquides par coprecipitation avec le carbonate de calcium: etude de laboratoire

Energy Technology Data Exchange (ETDEWEB)

Patti, F.; Gailledreau, C.; Cohen, P.

1961-02-24

As during the treatment by co-precipitation with calcium carbonate of liquid radioactive residues, a partial decontamination can be obtained by simply agitating an already formed radioactive sludge with the effluent to be processed, the authors study whether it would be possible to first perform a co-precipitation with a lower dose of calcium carbonate and then to complete decontamination by agitating with an adequate quantity of sludge stored during preceding operations. The authors report the study of the influence of reactant quantity on the chemical treatment efficiency, of the evolution of the activity of a radioactive residual solution in contact with a precipitate, of the cleaner element, of a precipitate reuse, of the technological and economic aspects, and of another possibility of reduction of the precipitate volume [French] Dans le traitement par coprecipitation avec le carbonate de calcium des residus radioactifs liquides, une decontamination partielle peut etre obtenue en agitant simplement une boue radioactive deja formee avec l'effluent a traiter. En consequence, il pourrait etre possible d'effectuer d'abord une coprecipitation avec une dose plus faible de carbonate de calcium et de completer ensuite la decontamination en agitant le liquide avec une quantite convenable de boue stockee a partir d'operations precedentes. (auteurs)

Du neuf dans les relations de l'Église orthodoxe avec les autres chrétiens

OpenAIRE

Famerée, Joseph

2015-01-01

Cette note évoque quatre réunions scientifiques (Athènes, Chambésy, Thessalonique, Iasi) qui, coup sur coup, de mai 2013 à mai 2014, ont permis à des Orthodoxes d’échanger avec d’autres chrétiens, catholiques notamment, sur des sujets théologiques et œcuméniques importants pour l’évolution des différentes Églises. Une nouvelle génération de théologiens orthodoxes se lève, osant parler librement à propos de leur Église et montrer l’écart entre l’Orthodoxie idéale et l’Orthodoxie réelle, spécia...

Reaction of uranium and plutonium carbides with austenitic steels; Reaction des carbures d'uranium et de plutonium avec des aciers austenitiques

Energy Technology Data Exchange (ETDEWEB)

Mouchnino, M [Commissariat a l' Energie Atomique, Fontenay-aux-Roses (France). Centre d' Etudes Nucleaires

1967-07-01

The reaction of uranium and plutonium carbides with austenitic steels has been studied between 650 and 1050 deg. C using UC, steel and (UPu)C, steel diffusion couples. The steels are of the type CN 18.10 with or without addition of molybdenum. The carbides used are hyper-stoichiometric. Tests were also carried out with UCTi, UCMo, UPuCTi and UPuCMo. Up to 800 deg. C no marked diffusion of carbon into stainless steel is observed. Between 800 and 900 deg. C the carbon produced by the decomposition of the higher carbides diffuses into the steel. Above 900 deg. C, decomposition of the monocarbide occurs according to a reaction which can be written schematically as: (U,PuC) + (Fe,Ni,Cr) {yields} (U,Pu) Fe{sub 2} + Cr{sub 23}C{sub 6}. Above 950 deg. C the behaviour of UPuCMo and that of the titanium (CN 18.12) and nickel (NC 38. 18) steels is observed to be very satisfactory. (author) [French] La reaction des carbures d'uranium et de plutonium avec des aciers austenitiques a ete etudiee entre 650 deg. C et 1050 deg. C a partir de couples de diffusion UC, acier et (UPu)C, acier. Les aciers sont du type CN 18.10 avec ou sans addition de molybdene. Les carbures utilises sont hyper-stoechiometriques. En outre on a fait des essais avec UCTi, UCMo, UPuCTi, UPuCMo. Jusqu'a 800 deg. C on ne detecte pas de diffusion sensible du carbone dans l'acier inoxydable. Entre 800 et 900 deg. C il y a diffusion dans l'acier du carbone provenant de la decomposition des carbures superieurs. A partir de 900 deg. C il y a decomposition du monocarbure selon une reaction que l'on ecrit schematiquement: (U,PuC) + (Fe, Ni, Cr) {yields} (U,Pu)Fe{sub 2} + Cr{sub 23}C{sub 6}. Nous notons a 950 deg. C le bon comportement de UPuCMo ainsi que celui des aciers au titane (CN 18. 12) et au nickel (NC 38.18). (auteur)

Airframe/Propulsion Interference

Science.gov (United States)

1975-03-01

point de recollement. abscisse. temperature absolue . trainee de culot. vltesse. X t abscisse. 6-2 X t distance inter-tuyeres. OC i angle...secondaire assurant deux roles principaux i tout d’abord guldage et melange du flux froid de ventilation et du jet chaud, ensuite adaptation des...l’ambiante et une valeur de V eL’:alo a 1,4 (air froid ). ’ On notera que les calculs effectuEs par la mEthode d’elements finis (v 2) ont eto

Survival at Sea for Mariners, Aviators and Search and Rescue Personnel (Survie en mer pour les marins, les aviateurs et le personnel de recherche et de sauvetage)

Science.gov (United States)

2008-02-01

of Figures viii List of Tables ix Preface x Technical Course HFM-152 xi Executive Summary and Synthèse ES-1 Chapter 1 – Introduction to the RTO...Survival at Sea for Mariners, Aviators and Search and Rescue Personnel (RTO-AG-HFM-152) Executive Summary This NATO RTO Technical Course on Marine...Lors d’accidents en eau froide, il est fort probable que le choc thermique dû au froid ainsi que l’épuisement à la nage entraînent davantage la

Analyse de L'ancrage des Vortex Intergrains pour le Yttrium BARYUM(2) CUIVRE(3) OXYGENE(7) Polycristallin

Science.gov (United States)

Fournier, Patrick

Le Modele de l'Etat Critique Generalise (MECG) est utilise pour decrire les proprietes magnetiques et de transport du YBa_2Cu_3O _7 polycristallin. Ce modele empirique permet de relier la densite de courant critique a la densite de lignes de flux penetrant dans la region intergrain. Deux techniques de mesures sont utilisees pour caracteriser nos materiaux. La premiere consiste a mesurer le champ au centre d'un cylindre creux en fonction du champ magnetique applique pour des temperatures comprises entre 20 et 85K. En variant l'epaisseur de la paroi du cylindre creux, il est possible de suivre l'evolution des cycles d'hysteresis et de determiner des champs caracteristiques qui varient en fonction de cette dimension. En utilisant un lissage des resultats experimentaux, nous determinons J _{co}, H_ {o} et n, les parametres du MECG. La forme des cylindres, avec une longueur comparable au diametre externe, entrai ne la presence d'un champ demagnetisant qui peut etre inclus dans le modele theorique. Ceci nous permet d'evaluer la fraction du volume ecrante, f _{g}, ainsi que le facteur demagnetisant N. Nous trouvons que J_{ co}, H_{o} et f_{g} dependent de la temperature, tandis que n et N (pour une epaisseur de paroi fixe) n'en dependent pas. La deuxieme technique consiste a mesurer le courant critique de lames minces en fonction du champ applique pour differentes temperatures. Nous utilisons un montage que nous avons developpe permettant d'effectuer ces mesures en contact direct avec le liquide refrigerant, i.e. dans l'azote liquide. Nous varions la temperature du liquide en variant la pression du gaz au-dessus du bain d'azote. Cette methode nous permet de balayer des temperatures entre 65K et la temperature critique du materiau ({~ }92K). Nous effectuons le lissage des courbes de courant critique en fonction du champ applique encore a l'aide du MECG, pour a nouveau obtenir ses parametres. Pour trois echantillons avec des traitements thermiques differents, les parametres

Un hommage à Benoît Mandelbrot (1924-2010) : zoom sur une représentation tridimensionnelle de l'ensemble de Mandelbrot avec 'mapping' des arguments

OpenAIRE

Colonna , Jean-François

2011-01-01

A tribute to Benoît Mandelbrot (1924-2010) : tridimensional zoom in on the Mandelbrot set with mapping of the arguments (Un hommage à Benoît Mandelbrot (1924-2010) : zoom sur une représentation tridimensionnelle de l'ensemble de Mandelbrot avec 'mapping' des arguments)

Measured and Modeled Long-Wave Infrared Signature of Quest in Q280

Science.gov (United States)

2008-03-01

l’eau chaude par rapport à l’air froid , a constitué un autre cas permet- tant de mieux comprendre les signatures infrarouge et de mettre au point des...d’intensité énergétique infrarouge à l’horizon et dans la valeur absolue de l’in- tensité énergétique de la mer : le modèle laisse prévoir...ports de l’Arctique favorise fortement d’autres recherches sur les signatures infrarouge des navires en eaux froides et dans des conditions hivernales

Study of high frequency instabilities on a cold cathode reflex discharge; Contribution a l'etude des instabilites a haute frequence dans la decharge reflex a cathodes froides

Energy Technology Data Exchange (ETDEWEB)

Gregoire, M [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1965-06-01

The cold cathode reflex discharge develops a cathode sheath of several hundreds of volts, which accelerates electrons released from the cathode to high velocities along the lines of the axial magnetic field. On the studied pressure range (4.10{sup -4} torr < p < 2.10{sup -2} torr) the plasma density is about 10{sup 11} cm{sup -3}. Under certain conditions high frequency (1 5000 MHz) instabilities appear. These instabilities are found to profoundly modify the mean characteristics of the discharge. In particular, particle flow across the lines of magnetic field is found to be considerably greater than that predicted by classical diffusion theory. Theoretical considerations are presented with complementary experimental results. They show that the high frequency instabilities are a result of the fast electronic assembly accelerated through the cathode sheath. (author) [French] Dans certaines conditions, qui sont precisees, des instabilites a haute frequence (1 5000 MHz) se developpent dans la decharge reflex a cathodes froides. Lorsque le plasma (n {approx_equal}10{sup 11} cm{sup -3}) est instable, les caracteristiques moyennes de la decharge sont profondement alterees. Les fuites de particules a travers les lignes de forces du champ magnetique statique applique deviennent en particulier trop importantes pour que le seul effet classique des collisions binaires puisse les expliquer. L'ionisation du gaz est assuree par une assemblee electronique qui acquiert dans les gaines cathodiques ({approx_equal} 500 volts) une vitesse, parallele au champ magnetique, importante. La discussion de resultats theoriques et une experience complementaire montrent que cette population d'electrons rapides, tres distincte de celle des electrons lents du plasma pour les pressions les plus faibles du domaine etudie (4.10{sup -4} torr < p < 2.10{sup -2} torr), est responsable des instabilites a haute frequence observees. (auteur)

Conversations avec Jules Hoüel regards sur la géométrie non euclidienne et l’analyse infinitésimale vers 1875

CERN Document Server

Nabonnand, Philippe

2017-01-01

Jules Hoüel (1823-1886) a occupé une place particulière dans les mathématiques en France durant la seconde partie du 19ème siècle. Par ses travaux de traduction et ses recensions, il a vivement contribué à la réception de la géométrie non euclidienne de Bolyai et Lobatchevski ainsi qu’aux débats sur les fondements de l’analyse. Il se situe au centre d’un vaste réseau international de correspondances en lien avec son rôle de rédacteur pour le Bulletin des sciences mathématiques et astronomiques. Cet ouvrage contient les correspondances actives et passives de Hoüel avec Joseph-Marie De Tilly, Gaston Darboux et Victor-Amédée Le Besgue ainsi qu’une introduction qui se focalise sur la découverte de l’impossibilité de démontrer le postulat des parallèles d’Euclide et l’apparition des premiers exemples de fonctions continues non dérivables.

Entretien avec M. Bernard Dormy, Président du TREF, courant novembre 2017

CERN Multimedia

Staff Association

2018-01-01

M. Bernard Dormy, Président du TREF (Tripartite Employment Conditions Forum) (voir Echo n° 242) a terminé son mandat à la fin de l'année 2017. L’Association du personnel a souhaité s’entretenir avec lui sur le CERN et son personnel et, entre autres, sur le modèle de concertation. Cette publication est également l’occasion pour l’Association du personnel de saluer M. Dormy pour l’engagement dont il a fait preuve depuis 2003, année où il a débuté au TREF comme délégué français. Il faut croire que son mandat au sein de ce forum lui a particulièrement plu, puisque M. Dormy a occupé les fonctions de Vice-président du TREF de 2007 à 2011, puis de Président de 2012 à 2017. Sous sa prési...

Reaction of uranium and plutonium carbides with nitrogen; Reaction avec l'azote des carbures d'uranium et de plutonium

Energy Technology Data Exchange (ETDEWEB)

Lorenzelli, R; Martin, A; Schickel, R [Commissariat a l' Energie Atomique, Fontenay-aux-Roses (France). Centre d' Etudes Nucleaires

1966-03-01

Uranium and plutonium carbides react with nitrogen during the grinding process preceding the final sintering. The reaction occurs even in argon atmospheres containing a few percent of residual nitrogen. The resulting contamination is responsible for the appearance of an equivalent quantity of higher carbide in the sintered products; nitrogen remains quantitatively in the monocarbide phase. UC can be transformed completely into nitride under a nitrogen pressure, at a temperature as low as 400 C. The reaction is more sluggish with PuC. The following reactions take places: UC + 0,8 N{sub 2} {yields}> UN{sub 1.60} + C and PuC + 0,5 N{sub 2} {yields} PuN + C. (authors) [French] Les carbures d'uranium et de plutonium reagissent avec l'azote au cours du broyage qui precede le frittage final. Cette reaction est sensible meme sous des atmospheres d'argon ne contenant que quelques pour cent d'azote. Cette contamination se traduit sur les produits frittes par l'apparition d'une quantite equivalente de carbure superieur, l'azote restant fixe quantitativement dans la phase monocarbure. On peut transformer entierement UC en nitrure par action de l'azote sous pression des 400 C. La reaction est plus difficile avec PuC. Les reactions sont les suivantes: UC + 0,8 N{sub 2} {yields} UN{sub 1.60} + C et PuC + 0,5 N{sub 2} {yields} PuN + C.

Oxygen toxicity

Directory of Open Access Journals (Sweden)

C. A. van der Westhuizen

1990-07-01

Full Text Available Oxygen has been discovered about 200 years ago. Since then the vital physiological involvement of oxygen in various biologi­cal processes, mainly energy production, has been established. However, in the body molecular oxygen can be converted to toxic oxygen metabolites such as superoxide anion, hydrogen peroxide, the hydroxyl radical and singlet oxygen. These toxic metabolites are produced mainly in the mitochondria, plasma membranes and endoplasmic reticulum.

Dosing of traces of oxygenated water by polarography; Dosage de traces d'eau oxygenee par polarographie

Energy Technology Data Exchange (ETDEWEB)

Faure, A. M.; Malterre, J.

1960-07-01

As dosing oxygenated water by using polarography has been envisaged within the framework of water purity controls for the Melusine pile, the objective of the authors is here to see whether the polarographic method could be satisfying for routine analyses, and would result in a higher dosing sensitivity. They describe the polarography principle, indicate devices which are used, specify and comment conditions under which polarography is performed [French] Le dosage de l'eau oxygenee par polarographie a ete envisage dans le cadre des controles de purete de l'eau de la pile Melusine. La methode calorimetrique dans les conditions de fonctionnement de Melusine a puissance maxima, avait mis en evidence des teneurs en H{sub 2}O{sub 2} produites par radiolyse de l'eau, inferieures a 20 ppm. Le but de cette etude, a ete de voir si la methode polarographique pouvait donner satisfaction en analyse de routine a ces teneurs la et permettre une plus grande sensibilite de dosage, la colorimetrie se limitant pratiquement a 1 ppm avec une precision de 20 pour cent environ. (auteurs)

Physico-Chimie des Atomcules d'Hélium antiprotonique: Modélisation de Processus réactifs en présence d'Antimatière

Science.gov (United States)

Sauge, Sébastien

2000-07-01

Environ 3%des antiprotons (p) stoppés dans l'hélium survivent plusieurs microsecondes, contre quelques picosecondes dans tout autre matériau. Cette métastabilité inhabituelle résulte d'une capture sur des états liés de l'atome exotique pHe+, dénommé atomcule car il s'apparente à la fois à un atome de Rydberg quasi-circulaire quasi-classique de grand moment angulaire l n-1 37et à une molécule diatomique composée d'un noyau chargé négativement et caractérisée par une forte excitation rotationnelle J=l. En dehors de cette structure duale originale accessible par spectroscopie laser, la physico-chimie de leur interaction avec d'autres atomes ou molécules a fait l'objet d'études microscopiques. Alors que les atomcules résistent à des millions de collisions dans l'hélium pur, des contaminants moléculaires comme H2 les détruisent immédiatement, y compris à basse température. Dans le cadre Born-Oppenheimer, nous interprétons l'interaction moléculaire, calculée par des techniques de chimie quantique {ab initio}, en termes de chemins réactifs classiques, qui présentent des barrières d'activation compatibles avec celles mesurées dans He et H2.Nous montrons par une approche Monte Carlo de trajectoires classiques que la thermalisation détruit fortement les populations initiales, portant la fraction estimée des états de capture à 3%. Nous étudions aussi la recombinaison dissociative pHe+ + e+ e -dans une approche de trajectoires classiques pour les noyaux: nous prédisons la synthèse d'antihydrogène avec un rapport de branchement de 10%, ainsi qu'une nouvelle classe d'atomcules métastables ?={p}, e+, 2e-, qui pourrait être confirmée par spectroscopie. Ce travail illustre la transférabilité des concepts de chimie physique à l'étude de processus exotiques en présence d'antimatière, et apporte un éclairage nouveau sur la physico-chimie des radicaux interstellaires froids.

Mixed oxygen ion/electron-conducting ceramics for oxygen separation

Energy Technology Data Exchange (ETDEWEB)

Stevenson, J.W.; Armstrong, T.R.; Armstrong, B.L. [Pacific Northwest National Lab., Richland, WA (United States)

1996-08-01

Mixed oxygen ion and electron-conducting ceramics are unique materials that can passively separate high purity oxygen from air. Oxygen ions move through a fully dense ceramic in response to an oxygen concentration gradient, charge-compensated by an electron flux in the opposite direction. Compositions in the system La{sub 1{minus}x}M{sub x}Co{sub 1{minus}y{minus}z}Fe{sub y}N{sub z}O{sub 3{minus}{delta}}, perovskites where M=Sr, Ca, and Ba, and N=Mn, Ni, Cu, Ti, and Al, have been prepared and their electrical, oxygen permeation, oxygen vacancy equilibria, and catalytic properties evaluated. Tubular forms, disks, and asymmetric membrane structures, a thin dense layer on a porous support of the same composition, have been fabricated for testing purposes. In an oxygen partial gradient, the passive oxygen flux through fully dense structures was highly dependent on composition. An increase in oxygen permeation with increased temperature is attributed to both enhanced oxygen vacancy mobility and higher vacancy populations. Highly acceptor-doped compositions resulted in oxygen ion mobilities more than an order of magnitude higher than yttria-stabilized zirconia. The mixed conducting ceramics have been utilized in a membrane reactor configuration to upgrade methane to ethane and ethylene. Conditions were established to balance selectivity and throughput in a catalytic membrane reactor constructed from mixed conducting ceramics.

Le combat avec l'ange

Directory of Open Access Journals (Sweden)

Christian Lalive d’Épinay

2007-06-01

Full Text Available L'auteur « revisite » le parcours qui l'a conduit à réaliser dans les années 1960 une des premières études du mouvement évangélique pentecôtiste en Amérique latine. Il rappelle d'abord les termes par lesquels il avait prétendu cadrer sa relation avec son objet de recherche, pour décrire ensuite l'étrange dialectique sujet/objet qui s'était développée au fur et à mesure de son immersion dans une double altérité, l'Amérique latine et le mouvement charismatique. Pendant ce voyage au long cours, l'« objet » avait pris vie ; il était devenu un sujet qui imposait au chercheur qui s'était cru « sujet » des interrogations nouvelles en même temps qu'une mise en question de ses certitudes du départ.The combat with the angel. Concerning a study on the Pentecostal movement in ChileThe author retraces the path that led him in the 1960s to carry out one of the first studies on the Pentecostal evangelical movement in Latin America. After recalling the terms on which he sought to situate his relationship with the research topic, he goes on to describe the strange subject/object dialectic that developed as he gradually became more and more immersed in a dual otherness, Latin America and the charismatic movement. During this lengthy voyage, the “object” of his research took on a life of its own, mutating into a subject that confronted the researcher (who had assumed that he was the “subject” with new questions and a need to reconsider his initial certitudes.La pelea con el ángel. Acerca de un estudio del movimiento pentecostal en ChileEl autor “revisita” el camino que lo había llevado a desarrollar uno de los primeros estudios sobre el movimiento evangélico pentecostal en América latina en los años’60. Recuerda primero los términos con los que había pretendido encuadrar la relación con su objeto de investigación, para describir luego el extraño vínculo sujeto/objeto que se había ido generando mientras

The interaction of circularly polarised electromagnetic waves with a plasma; Interaction d'ondes electromagnetiques a polarisation circulaire avec un plasma

Energy Technology Data Exchange (ETDEWEB)

Consoli, T; Legardeur, R; Slama, L [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1961-07-01

The interaction of left and right handed circularly polarised waves with a plasma are studied. The individual trajectories of charges of both signs are traced with a analogical simulator. Applications to plasma heating and diagnostic are deduced. (author) [French] On etudie l'interaction des ondes a polarisation circulaire droite ou gauche avec un plasma. Les trajectoires individuelles des charges sont tracees a l'aide d'un dispositif analogique. On en deduit les applications au chauffage d'un plasma et a la mesure de ses parametres caracteristiques. (auteur)

Closed Loop Control of Oxygen Delivery and Oxygen Generation

Science.gov (United States)

2017-08-01

were used for this study and were connected via a USB cable to allow communication. The ventilator was modified to allow closed loop control of oxygen...connected via a USB cable to allow communication. The ventilator was modified to allow closed loop control of oxygen based on the oxygen saturation...2017-4119, 28 Aug 2017. oximetry (SpO2) and intermittent arterial blood sampling for arterial oxygen tension (partial pressure of oxygen [PaO2]) and

High-Energy-Density Metal-Oxygen Batteries: Lithium-Oxygen Batteries vs Sodium-Oxygen Batteries.

Science.gov (United States)

Song, Kyeongse; Agyeman, Daniel Adjei; Park, Mihui; Yang, Junghoon; Kang, Yong-Mook

2017-12-01

The development of next-generation energy-storage devices with high power, high energy density, and safety is critical for the success of large-scale energy-storage systems (ESSs), such as electric vehicles. Rechargeable sodium-oxygen (Na-O 2 ) batteries offer a new and promising opportunity for low-cost, high-energy-density, and relatively efficient electrochemical systems. Although the specific energy density of the Na-O 2 battery is lower than that of the lithium-oxygen (Li-O 2 ) battery, the abundance and low cost of sodium resources offer major advantages for its practical application in the near future. However, little has so far been reported regarding the cell chemistry, to explain the rate-limiting parameters and the corresponding low round-trip efficiency and cycle degradation. Consequently, an elucidation of the reaction mechanism is needed for both lithium-oxygen and sodium-oxygen cells. An in-depth understanding of the differences and similarities between Li-O 2 and Na-O 2 battery systems, in terms of thermodynamics and a structural viewpoint, will be meaningful to promote the development of advanced metal-oxygen batteries. State-of-the-art battery design principles for high-energy-density lithium-oxygen and sodium-oxygen batteries are thus reviewed in depth here. Major drawbacks, reaction mechanisms, and recent strategies to improve performance are also summarized. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Oxygen Therapy

Directory of Open Access Journals (Sweden)

Bonnie Solmes

2000-01-01

Full Text Available LTOT is prescribed for people with chronic lung disease in whom there is a decrease in the ability of the lungs to supply enough oxygen to the body. The heart is obliged to pump faster to meet the body's oxygen requirements. This may place undue stress on the heart, resulting in palpitations, dizziness and fatigue. A low oxygen level in arterial blood is also harmful to the heart, the brain and the pulmonary blood vessels. Oxygen therapy is used to break this cycle. A person with low blood oxygen will often be able to accomplish more with less fatigue with the help of supplemental oxygen therapy. Shortness of breath is a mechanical problem resulting from the effects of chronic obstructive pulmonary disease. Oxygen therapy may or may not reduce shortness of breath, but it will help the lungs and heart to function with less stress.

Pompe de chaleur fonctionnant avec un mélange de fluides Heat Pump Operating with a Fluid Mixture

Directory of Open Access Journals (Sweden)

Vidal J.

2006-11-01

Full Text Available Lorsqu'une pompe de chaleur échange de la chaleur avec des fluides extérieurs, dont la température évolue au cours de l'échange, il est possible d'augmenter le coefficient de performance en utilisant comme fluide de travail un mélange non-azéotropique qui se vaporise et se condense suivant une évolution de température parallèle à celle du fluide extérieur avec lequel s'effectue cet échange. L'utilisation de mélanges dans les pompes de chaleur a été étudiée, d'une part, au moyen de modèles de simulation sur ordinateur et, d'autre part, au moyen d'essais expérimentaux. Différentes applications ont été examinées à la fois dans le domaine du chauffage résidentiel et dans le domaine industriel. Whenever heat is recovered and delivered, the coefficient of performance of a heat pump can be increased by using a fluid mixture selected to have a temperature variation, during the vaporization and condensation stages, parallel to that of the outside fluid with which the heat exchange takes place. Such a solution was investigated both theoretically and experimentally. It has been shown that significant savings can be expected, ranging up to 50% of the energy consumption of conventional heat pumps in some cases. Various applications for home and industrial heating have been examined, and the economic prospects have been found to be satisfactory. Further work is needed to develop such heat pumps on a commercial basis.

[Domiciliary oxygen therapy].

Science.gov (United States)

Abdel Kafi, S

2010-09-01

In Belgium, oxygen therapy is becoming more and more accessible. When oxygen is needed for short periods or for special indications as palliative care, an agreement between mutual insurance companies and pharmacists allows the practitioner the home installation of gazeous oxygen cylinder or of oxygen concentrator. When long term oxygen therapy (LTOT) is indicated for patients with respiratory insufficiency, the pneumologist must first ask the INAMI the authorization to install one of the following modalities: oxygen concentrator with or without demand oxygen delivery cylinder and liquid oxygen. The goal of LTOT is to increase survival and quality of life. The principal and well accepted indication for LTOT is severe hypoxemia. The beneficial effects of oxygen therapy limited at night or on exertion are controversial. In order to increase patient's autonomy, oxygen can be prescribed for ambulation, respecting prescription's rules. At each step of oxygen therapy implementing (indication, choice of the device and follow-up) the patient under oxygen may benefit from a joint approach between the general practitioner and the chest specialist.

Oxygen therapy - infants

Science.gov (United States)

... breathe increased amounts of oxygen to get normal levels of oxygen in their blood. Oxygen therapy provides babies with the extra oxygen. Information Oxygen is a gas that the cells in your body need to work properly. The ...

Emission d'effluents gazeux lors du compostage de substrats organiques en relation avec l'activité microbiologique (nitrification/dénitrification)

OpenAIRE

Yulipriyanto , Hiéronymus

2001-01-01

Co-tutelle avec l'Indonesie; The awakening of the importance of the waste management and the safeguarding of resources led actors of the agricultural world more and more to be interested in composting as a mode of waste processing of breeding effluents or mud of wastewater treatment plants. The ways of use for these substrates, spreading, composting or other, must thus be compared. One knows indeed that agriculture is responsible for a significant share of the ammonia (NH3) and nitrous oxide ...

Oxygen diffusion and oxygen effect in tumor tissue

International Nuclear Information System (INIS)

Eissa, H.M.; Hehn, G.

1979-06-01

The diffusion of oxygen in tumor cords of bronchus carcinoma of the lung have been studied with refined computer methods for solving the diffusion equation in axis symmetric tumor structures. In this tumor configuration we may find three different regions consisting of euoxic cells, hypoxic tumor cells and necrotic parts. In the case of oxygen supply from a capillary inside a cylinder of tumor tissue with radius 200 μm or in a tumor cord of radius 300 μm with oxygen supply by capillaries outside, we get a relation of well oxygenated cells to hypoxic cells approximately as 1:8 or as 1:1.1 respectively. Of course most of the tumor cords observed in histological slices have smaller diameters, so that an average of approximately 20% hypoxic cells can be assumed. Based on the work of Ardenne, the diffusion of oxygen and glucose in a tumor of type DS-carcinosarcom has been investigated in both intact tumor and tumor treated with ionizing radiation. We can show that a strong reoxygenation effect takes place in that the well supplied regions may increase in some tumor configurations up to a factor of four by volume. The biological consequences of the oxygen pressure determined in tumor cells are discussed in detail. The investigation of oxygen diffusion in the intercapillary tumor region should give a quantitative physical basis for considering the oxygen effect with the aim to explain the advantages of neutron therapy against conventional radiotherapy. (orig./MG) [de

Oxygen effect and intracellular oxygen content (adaptation hypothesis)

Energy Technology Data Exchange (ETDEWEB)

Yarmonenko, S P; Ehpshtejn, I M [Akademiya Meditsinskikh Nauk SSSR, Moscow. Onkologicheskij Tsentr

1977-01-01

Experimental data indicating that a radiomodifying action of hypoxia is dependent on the ''prehistory'' of the irradiated object are considered. This dependence manifests itself in a decreased protective action of acute hypoxia on the hypoxia-adapted objects. To explain this a hypothesis is proposed connecting a degree of cell radiosensitivity modification, determined by the oxygen effect, with the intracellular oxygen content. The latter, in accord with current ideas, is regulated by variations in the diffusion resistance to oxygen shown by the cytoplasmic membranes depending on the energy level of the cell and the degree of its oxygenation.

Oxygen effect and intracellular oxygen content (adaptation hypothesis)

International Nuclear Information System (INIS)

Yarmonenko, S.P.; Ehpshtejn, I.M.

1977-01-01

Experimental data indicating that a radiomodifying action of hypoxia is dependent on the ''prehistory'' of the irradiated object are considered. This dependence manifests itself in a decreased protective action of acute hypoxia on the hypoxia-adapted objects. To explain this a hypothesis is proposed connecting a degree of cell radiosensitivity modification, determined by the oxygen effect, with the intracellular oxygen content. The latter, in accord with current ideas, is regulated by variations in the diffusion resistance to oxygen shown by the cytoplasmic membranes depending on the energy level of the cell and the degree of its oxygenation

Theory and development of fluorescence-based optochemical oxygen sensors: oxygen optodes.

Science.gov (United States)

Opitz, N; Lübbers, D W

1987-01-01

As the preceding considerations concerning the physical and technical features of oxygen optodes have demonstrated, fluorescence-based optochemical oxygen sensors possess certain advantages and peculiarities compared to conventionally applied electrochemical sensors such as polarographic oxygen electrodes. First, in contrast to oxygen electrodes, oxygen measurements with oxygen optodes do not suffer from distortions caused by the reference electrodes. In addition, because of the polarographic process, platinum electrodes continuously consume oxygen, which falsifies the results, especially when small sample volumes or long-term measurements, or both, are involved, whereas the sensor layer of oxygen optodes must only be equilibrated. Moreover, the surface of the platinum wire has to be catalytically clean in order to obtain a plateau of the polarogram and, consequently, to achieve a low rest current at zero PO2. Unfortunately, the demand for catalytically clean platinum surfaces turns out to be rather critical, since surface contamination occurs even with membranized electrodes, resulting in the well-known phenomenon of "electrode poisoning." The question of the specificity of oxygen electrodes also must be considered. In this context, CO2 and halothane may interfere with oxygen measurements, whereas fluorescence quenching is unaffected by CO2 and halothane affects the measurements only slightly, depending on the special indicator used. Furthermore, because of the flow dependence, oxygen measurements with the oxygen electrode show a distinct "stirring effect" caused by the turbulence in front of the electrode, which disturbs the diffusion field. Because of the completely different physical principle of fluorescence optical sensors, such influences are not observed with oxygen optodes. In addition, isolation and shielding of electrical circuits found in electrodes are not necessary for optodes. Furthermore, the sensitivity of oxygen optodes can be tuned to the desired

Effet de la substitution du cuivre par du lithium sur les proprietes de l'oxyde spinelle lithium(x)cuivre(y-x)cobalt(3-y)oxygen(4) etudie pour l'electrocatalyse de la reaction de degagement de l'oxygene en milieu alcalin

Science.gov (United States)

Fatih, Khalid

L'electrolyse de l'eau demeure la seule technologie industrielle de generation de l'hydrogene et de l'oxygene tres purs sans rejet de CO2 dans l'atmosphere, ce qui le rend tres attrayant par rapport a la combustion de carburants fossiles qui provoque presentement de serieux problemes environnementaux. Dans le but d'ameliorer le rendement de ce procede, nous avons developpe de nouveaux materiaux d'anode peu couteux, a base de l'oxyde mixte CuyCo3-yO 4, qui possedent une cinetique rapide pour la reaction de degagement de l'oxygene (RDO). Cette reaction suscite un interet particulier en raison de la surtension d'activation relativement elevee a l'anode qui cause la principale perte de rendement du procede. Une etude systematique a ete effectuee sur la substitution du Cu par du Li (0 a 40%), afin d'elucider les proprietes electrocatalytiques des oxydes LixCuy-xCo3-yO4. Ces oxydes, prepares sous forme de poudres par decomposition thermique des nitrates precurseurs entre 300 et 500°C, ont montre (DRX et FTIR) une structure spinelle inverse non-stcechiometrique avec une diminution du volume de la maille cristalline. La surface specifique par BET est d'environ 6 m2 g-1. Le pcn, obtenu par titrage acido-basique, a indique une diminution de la force du lien M-OH avec le taux du Li dans l'oxyde. Les analyses par XPS, realisees sur des films d'oxyde prepares par nebulisation reactive sur un substrat lisse de nickel, revelent un enrichissement de la surface en Cu a partir de 30% Li, et la presence des cations de surface Co2+, Co3+, Cu +, Cu2+ et Cu3+. La concentration de ce dernier montre un maximum a 10 et 20% Li. Suite a la substitution du Cu par du Li, la compensation de la charge serait assuree principalement par la formation d'especes Cu3+ pour les oxydes contenant jusqu'a 20% Li, et par la formation d'especes Co3+ aux taux de substitution superieurs. Les micrographies MEB montrent une morphologie hemispherique des particules d'oxyde reparties uniformement sur le substrat

Oxygen Therapy

Science.gov (United States)

... their breathing to dangerously low levels. Will I need oxygen when I sleep? Usually if you use supplemental oxygen during the ... your health care provider tells you you only need to use oxygen for exercise or sleep. Even if you feel “fine” off of your ...

Retinal Vessel Oxygen Saturation during 100% Oxygen Breathing in Healthy Individuals.

Directory of Open Access Journals (Sweden)

Olof Birna Olafsdottir

Full Text Available To detect how systemic hyperoxia affects oxygen saturation in retinal arterioles and venules in healthy individuals.Retinal vessel oxygen saturation was measured in 30 healthy individuals with a spectrophotometric retinal oximeter (Oxymap T1. Oximetry was performed during breathing of room air, 100% oxygen (10 minutes, 6L/min and then again room air (10 minutes recovery.Mean oxygen saturation rises modestly in retinal arterioles during 100% oxygen breathing (94.5%±3.8 vs. 92.0%±3.7% at baseline, p<0.0001 and dramatically in retinal venules (76.2%±8.0% vs. 51.3%±5.6%, p<0.0001. The arteriovenous difference decreased during 100% oxygen breathing (18.3%±9.0% vs. 40.7%±5.7%, p<0.0001. The mean diameter of arterioles decreased during 100% oxygen breathing compared to baseline (9.7±1.4 pixels vs. 10.3±1.3 pixels, p<0.0001 and the same applies to the mean venular diameter (11.4±1.2 pixels vs. 13.3±1.5 pixels, p<0.0001.Breathing 100% oxygen increases oxygen saturation in retinal arterioles and more so in venules and constricts them compared to baseline levels. The dramatic increase in oxygen saturation in venules reflects oxygen flow from the choroid and the unusual vascular anatomy and oxygen physiology of the eye.

Recommandations nutritionnelles pratiques avec exemples de menus pour personnes vivant avec le VIH/SIDA en Afrique Noire

Directory of Open Access Journals (Sweden)

Estelle Anaelle Nguewo

2008-07-01

Full Text Available L’infection par le VIH (Virus de l’Immunodéficience Humaine est une infection chronique incurable. L’infection au VIH cause jusqu’à présent des millions de morts et entrave l’économie des pays sous développés ou en voie de développement, en l’occurrence les pays d’Afrique subsaharienne. Le but principal de la thérapie nutritionnelle en cas d’infection par le VIH est d’assurer au patient un poids normal et une alimentation appropriée couvrant ses besoins nutritionnels pendant les différentes phases de l’infection. Nous proposons des recommandations alimentaires détaillées quant aux apports recommandés en nutriments (macro- et micronutriments pour les personnes vivant avec le VIH/SIDA. La nutrition joue en général un rôle très important dans le fonctionnement optimal du système immunitaire. Puisque l’infection par le VIH/SIDA est une maladie du système immunitaire, elle influence de plusieurs manières l’état nutritionnel du patient. Une nutrition hyper calorifique et hyper protéinée saine, variée et adaptée aux besoins de l’organisme est une condition indispensable pour rester longtemps en forme en cas d’infection par le VIH/SIDA. Elle permet en outre de garder un poids normal pendant la phase asymptomatique de l’infection et d’augmenter son poids pendant la phase symptomatique. Ceci a pour but de freiner l’évolution de l’infection vers le stade SIDA. Les personnes atteintes par le VIH/SIDA devraient en plus avoir une bonne hygiène de vie et exercer régulièrement une activité sportive modérée. Elles devraient mettre l’accent sur leur protection contre toute intoxication alimentaire et sur le renforcement de leur système immunitaire. Il est en outre important en plus du besoin en nutriments des personnes atteintes par le VIH/SIDA, de tenir compte de leur situation financière et culturelle, car en Afrique il existe sur ce point une très grande différence dans la population. C�

Modélisation d'une détente quasi-isotherme d'un gaz par contact direct avec un fluide caloporteur

OpenAIRE

Blaise , Mathilde; Maillet , Denis; Feidt , Michel; Alemany , Antoine; Forcinetti , Renato

2015-01-01

National audience; Les besoins en électricité sont croissants, cependant, les rejets thermiques industriels sont peu valorisés. La reconsidération des moteurs à apport de chaleur externe est un enjeu d'actualité pour la valorisation des rejets thermiques. Dans ces derniers, la phase de détente motrice offre des possibilités d'amélioration. L'idée ici est d'accompagner cette étape par un apport de chaleur par contact direct avec un fluide caloporteur. En effet, la détente d'un gaz entre une ha...

Development of ultracold neutron detectors and a polarization analyzing system for the measurement of the neutron electric dipole moment; Developpement de detecteurs de neutrons ultra-froids et d'un systeme d'analyse de polarisation pour la mesure du moment electrique dipolaire du neutron

Energy Technology Data Exchange (ETDEWEB)

Rogel, Gwendal

2009-10-29

This thesis was performed in the context of a project aiming to measure the electric dipole moment (EDM) of the neutron at the Paul Scherrer Institute. Two aspects have been studied: The detection and the polarization analysis of ultracold neutrons. Three types of detectors have been tested at the Institut Laue-Langevin (ILL): The Cascade-U (GEM technology), the {sup 3}He gas detector and {sup 6}Li-doped glass scintillators (GS family). Their detection efficiency and their background sensitivity have been measured. The GS10 scintillator is competitive with the {sup 3}He gas detector under the conditions realized with the EDM spectrometer. A GS3/GS20 scintillator stack has enabled to improve the neutron/gamma discrimination. It has been found 20% less efficient than the {sup 3}He gas detector under the EDM spectrometer. The Cascade-U detector has been observed to be 20% less efficient than a 500 microns thick GS10 glass as confirmed by simulations. A new system for simultaneous spin analysis is presented. It consists of two independent detection systems (arms) which are each made of an adiabatic spin flipper, a spin analyzer, and a detector. The arms detect opposite spin components, allowing the simultaneous counting of both neutron spin orientations. A prototype mounted in horizontal configuration has been tested at ILL. The analyzing power of both arms has been measured to be 80%. The transmission of the system without spin analyzers has been found to be 50%. (author) [French] Cette these s'inscrit dans un nouveau projet de mesure du moment dipolaire electrique (EDM) du neutron a l'institut Paul Scherrer. Deux aspects ont ete etudies ici: la detection et l'analyse de polarisation de neutrons ultra-froids. Trois types de detecteurs ont ete testes a l'Institut Laue-Langevin (ILL): le Cascade-U (technologie GEM), le compteur a gaz {sup 3}He et des scintillateurs dopes au {sup 6}Li (type GS). Leur efficacite de detection ainsi que leur sensibilite au bruit de fond ont

Les politiques d’appui à l’agriculture familiale au Brésil : quelques éléments de comparaison avec le Maroc

Directory of Open Access Journals (Sweden)

Philippe Bonnal

2015-10-01

Full Text Available Au Brésil comme au Maroc, le secteur agricole est marqué par des différences extrêmes en termes de taille d’exploitation, ainsi que de niveaux d’équipement, de capitalisation et de techniques. L’article présente la politique brésilienne d’appui à l’agriculture familiale, et quelques éléments de comparaison avec les choix faits au Maroc. Les politiques agricoles brésiliennes proposent depuis une vingtaine d’années un appui spécifique aux exploitations familiales, avec notamment la constitution d’un ministère spécifique. De nombreux dispositifs d’appui à l’agriculture familiale ont été mis en place, dont notamment des crédits à taux préférentiel et des programmes d’achat de denrées agricoles pour les institutions publiques (écoles, hôpitaux, etc.. Dans les zones rurales particulièrement fragiles, des dispositifs permettent une coordination entre l’ensemble des politiques publiques concernant ces zones. Enfin, la conception et la mise en oeuvre de ces politiques publiques se font avec une forte implication des syndicats agricoles. Les politiques publiques brésiliennes et marocaines reconnaissent la dualité du monde agricole, mais cette dualité est définie par zone au Maroc, tandis qu’elle est fondée sur des caractéristiques explicites des exploitations au Brésil. Dans les deux pays, le coeur des politiques publiques d’appui aux exploitations familiales porte sur l’aide à l’investissement. Au-delà de ce coeur commun, les politiques brésiliennes ont plus spécifiquement développé des approches au niveau des territoires locaux et associent plus fortement qu’au Maroc les organisations professionnelles agricoles représentant l’agriculture familiale dans la conception de l’action publique. La comparaison des politiques agricoles au Maroc et au Brésil sur quelques éléments permet de souligner la forte étendue des choix qu’il est possible de considérer, pour définir des

29 August 2013 - J.-F. Jauslin, Directeur de l’Office fédéral de la culture (OFC) Ambassadeur suisse auprès de l’UNESCO et de l’OIF au 1er septembre 2013 Confédération suisse visite le centre visiteurs de l’expérience ATLAS ainsi que la caverne expérimentale d'ATLAS avec P. Jenny, ancien Porte-parole d'ATLAS. M. Bona, Conseiller du Directeur général pour les relations avec les Organisations internationales présent tout au long.

CERN Multimedia

Jean-Claude Gadmer

2013-01-01

29 August 2013 - J.-F. Jauslin, Directeur de l’Office fédéral de la culture (OFC) Ambassadeur suisse auprès de l’UNESCO et de l’OIF au 1er septembre 2013 Confédération suisse visite le centre visiteurs de l’expérience ATLAS ainsi que la caverne expérimentale d'ATLAS avec P. Jenny, ancien Porte-parole d'ATLAS. M. Bona, Conseiller du Directeur général pour les relations avec les Organisations internationales présent tout au long.

Oxygen-Partial-Pressure Sensor for Aircraft Oxygen Mask

Science.gov (United States)

Kelly, Mark; Pettit, Donald

2003-01-01

A device that generates an alarm when the partial pressure of oxygen decreases to less than a preset level has been developed to help prevent hypoxia in a pilot or other crewmember of a military or other high-performance aircraft. Loss of oxygen partial pressure can be caused by poor fit of the mask or failure of a hose or other component of an oxygen distribution system. The deleterious physical and mental effects of hypoxia cause the loss of a military aircraft and crew every few years. The device is installed in the crewmember s oxygen mask and is powered via communication wiring already present in all such oxygen masks. The device (see figure) includes an electrochemical sensor, the output potential of which is proportional to the partial pressure of oxygen. The output of the sensor is amplified and fed to the input of a comparator circuit. A reference potential that corresponds to the amplified sensor output at the alarm oxygen-partial-pressure level is fed to the second input of the comparator. When the sensed partial pressure of oxygen falls below the minimum acceptable level, the output of the comparator goes from the low state (a few millivolts) to the high state (near the supply potential, which is typically 6.8 V for microphone power). The switching of the comparator output to the high state triggers a tactile alarm in the form of a vibration in the mask, generated by a small 1.3-Vdc pager motor spinning an eccentric mass at a rate between 8,000 and 10,000 rpm. The sensation of the mask vibrating against the crewmember s nose is very effective at alerting the crewmember, who may already be groggy from hypoxia and is immersed in an environment that is saturated with visual cues and sounds. Indeed, the sensation is one of rudeness, but such rudeness could be what is needed to stimulate the crewmember to take corrective action in a life-threatening situation.

Accès aux soins des personnes originaires d&8217;Afrique subsaharienne vivant avec une hépatite B chronique

OpenAIRE

Vignier, N.; Spira, R. D.; Lert, F.; Pannetier, J.; Ravalihasy, Andrainolo; Gosselin, A.; Lydie, N.; Bouchaud, O.; Desgrées du Loû, Annabel; Grp, Anrs-Parcours

2017-01-01

Objectif : L'objectif de cette étude est d'analyser l'accès aux soins des personnes originaires d'Afrique subsaharienne (ASS) vivant avec une hépatite B chronique (HBC) en France. Méthodes : L'enquête ANRS-Parcours est une étude biographique réalisée en 2012-2013 auprès de personnes originaires d'ASS recrutées dans des services de prise en charge de l'HBC en Ile-de-France. Les données ont été recueillies en face-à-face à l'aide d'une grille biographique et d'un questionnaire standardisé. ...

Density functional theory study the effects of oxygen-containing functional groups on oxygen molecules and oxygen atoms adsorbed on carbonaceous materials.

Science.gov (United States)

Qi, Xuejun; Song, Wenwu; Shi, Jianwei

2017-01-01

Density functional theory was used to study the effects of different types of oxygen-containing functional groups on the adsorption of oxygen molecules and single active oxygen atoms on carbonaceous materials. During gasification or combustion reactions of carbonaceous materials, oxygen-containing functional groups such as hydroxyl(-OH), carbonyl(-CO), quinone(-O), and carboxyl(-COOH) are often present on the edge of graphite and can affect graphite's chemical properties. When oxygen-containing functional groups appear on a graphite surface, the oxygen molecules are strongly adsorbed onto the surface to form a four-member ring structure. At the same time, the O-O bond is greatly weakened and easily broken. The adsorption energy value indicates that the adsorption of oxygen molecules changes from physisorption to chemisorption for oxygen-containing functional groups on the edge of a graphite surface. In addition, our results indicate that the adsorption energy depends on the type of oxygen-containing functional group. When a single active oxygen atom is adsorbed on the bridge site of graphite, it gives rise to a stable epoxy structure. Epoxy can cause deformation of the graphite lattice due to the transition of graphite from sp2 to sp3 after the addition of an oxygen atom. For quinone group on the edge of graphite, oxygen atoms react with carbon atoms to form the precursor of CO2. Similarly, the single active oxygen atoms of carbonyl groups can interact with edge carbon atoms to form the precursor of CO2. The results show that oxygen-containing functional groups on graphite surfaces enhance the activity of graphite, which promotes adsorption on the graphite surface.

Chemical Looping Pilot Plant Results Using a Nickel-Based Oxygen Carrier Résultats de l’expérimentation sur un pilote opérant en boucle chimique avec un matériau transporteur d’oxygène à base de nickel

Directory of Open Access Journals (Sweden)

Pröll T.

2011-04-01

Full Text Available A chemical looping pilot plant was designed, built and operated with a design fuel power of 120 kW (lower heating value, natural gas. The system consists of two Circulating Fluidized Bed (CFB reactors. Operating results are presented and evaluated for a highly reactive nickel-based oxygen carrier, total system inventory 65 kg. The performance in fuel conversion achieved is in the range of 99.8% (CH4 conversion and 92% (CO2 yield. In chemical looping reforming operation, it can be reported that thermodynamic equilibrium is reached in the fuel reactor and that all oxygen is absorbed in the air reactor as soon as the global stoichiometric air/fuel ratio is below 1 and the air reactor temperature is 900°C or more. Even though pure natural gas (98.6 vol.% CH4 without steam addition was fed to the fuel reactor, no carbon formation has been found as long as the global stoichiometric air/fuel ratio was larger than 0.4. Based on the experimental findings and on the general state of the art, it is concluded that niche applications such as industrial steam generation from natural gas or CO2-ready coupled production of H2 and N2 can be interesting pathways for immediate scale-up of the technology. Un pilote d’étude de la combustion en boucle chimique d’une puissance thermique de 120 kW a été dimensionné, construit et opéré. Il est constitué de deux lits circulants interconnectés. Les résultats d’opération qui sont présentés ont été obtenus avec un matériau transporteur d’oxygène très réactif à base de nickel. L’inventaire total du matériau est de 65 kg dans le pilote. La conversion du méthane atteinte est voisine de 99,8 % et le rendement en CO2 est de 92 %. Lorsqu’on opère en mode de reformage, l’équilibre thermodynamique est atteint dans le réacteur fioul. Tout l’oxygène est capté dans le réacteur air dès que le rapport stoechiométrique entre l’air et le méthane est inférieur à 1 et que la temp

Combined deterministic and stochastic approaches applied to the food cold chain

OpenAIRE

Laguerre , O.; Hoang , M.H.; Derens , E.; Alvarez , G.; Flick , D.

2012-01-01

International audience; Plusieurs enquêtes ont montré que la température de produits dans les 3 dernières étapes de la chaîne du froid est problématique: meuble frigorifique de vente, transport par les consommateurs après l’achat et réfrigérateur domestique. Cette étude a été effectuée pour proposer une méthodologie de prédiction de l'évolution de la température du produit et de la charge microbienne tout au long de la chaine du froid. Les modèles déterministes développés prennent en compte l...

The Application of Oxygen Concentration Cells with the Solid Electrolyte ZrO{sub 2} * CaO to Thermodynamic Research; Emploi des Cellules a Concentration d'Oxygene avec Electrolyte Soude de ZrO{sub 2} * CaO, Dans les Recherches en Thermodynamique; Primenenie kislorodnykh kontsentratsionnykh kamer s tverdym ehlektrolitom ZrO{sub 2} * CaO dlya issledovanij po termodinamike; Aplicacion de las Celdas de Concentracion de Oxigeno con Electrolito Solido de ZrO{sub 2} * CaO a las Investigaciones Termodinamicas

Energy Technology Data Exchange (ETDEWEB)

Matsushita, Y.; Goto, K. [University of Tokyo (Japan)

1966-01-15

metallurgiques, faits au moyen des cellules a concentration d'oxygene avec electrolyte de ZrO{sub 2} * CaO, lequel assure une conduction anionique pure grace a la migration de defauts d'oxygene. Ces travaux sont les suivants: 1. Les energies libres types de formation de FeO, Fe{sub 3}O{sub 4}, SnO, PbO, Cu{sub 2}O, CuO et Ta{sub 2}O{sub 5} ont ete mesurees pour des temperatures de 500 a 1300 Degree-Sign C et exprimees en fonction de la temperature, les valeurs obtenues etant comparees aux donnees publiees. 2. La pression d'oxygene dans la solution liquide PbO-SiO{sub 2} a ete mesuree pour des temperatures de 800 a 1100 Degree-Sign C, l'equilibre etant realise a l'aide de plomb a l'etat liquide. Les activites chimiques de PbO et SiO{sub 2}, ainsi que les proprietes thermodynamiques de la solution ont ete determinees. 3. L'un des auteurs a mesure l'activite chimique de l'etain dans une solution liquide binaire de Pb-Sn pour des temperatures de 700 a 900 Degree-Sign C. Il a determine par des calculs les proprietes thermodynamiques d'alliages Pb-Sn. 4. En outre, il a mis au point un manometre a oxygene' pour mesurer la pression partielle de l'oxygene dans les gaz a haute temperature (500 a 1300 Degree-Sign C)dans l'intervalle 10{sup -1} a 10{sup -20} atm. Il a obtenu des valeurs autoconsistantes et reproductibles pour la force.electromotrice avec des melanges gazeux differents. 5. Les vitesses d'oxydation ou de reduction du fer pur et des oxydes de fer par un melange gazeux CO-CO{sub 2} ont ete mesurees au moyen du manometre entre 900 et 1000 Degree-Sign C. 6. Au moyen des electrodes de reference en graphite ou en poudre de (Ni + NiO), on a mesure la pression d'oxygene dans du fer a l'etat liquide, a differents teneurs en carbone, sature d'oxygene. Il semble que cette methode pourrait servir a determiner la teneur en oxygene du fer a l'etat liquide entre 1500 a 1600 Degree-Sign C. Enfin, les auteurs indiquent d'autres possibilites pour l'emploi de cellules a concentration d'oxygene

Oxygen permeation through oxygen ion oxide-noble metal dual phase composites

NARCIS (Netherlands)

Chen, C.S.; Chen, C.S.; Kruidhof, H.; Bouwmeester, Henricus J.M.; Verweij, H.; Burggraaf, Anthonie; Burggraaf, A.J.

1996-01-01

Oxygen permeation behaviour of three composites, yttria-stabilized zirconia-palladium, erbia-stabilized bismuth oxidenoble metal (silver, gold) was studied. Oxygen permeation measurements were performed under controlled oxygen pressure gradients at elevated temperatures. Air was supplied at one side

Silence et divulgation dans des familles d’adolescents vivant avec le VIH depuis la naissance : une exploration qualitative

Science.gov (United States)

Proulx-Boucher, Karène; Blais, Martin; Fernet, Mylène; Richard, Marie-Ève; Otis, Joanne; Josy Lévy, Joseph; Samson, Johanne; Lapointe, Normand; Morin, Guylaine; Thériault, Jocelyne; Trottier, Germain

2011-01-01

OBJECTIF : Les études ciblant les enfants nés avec le VIH se sont principalement intéressées à la période précédant l’annonce du diagnostic à l’enfant. L’objectif de cette étude est d’explorer les dynamiques de communication intrafamiliale suivant l’annonce du diagnostic. MÉTHODOLOGIE : Vingt-neuf jeunes (de dix à 18 ans) vivant avec le VIH depuis la naissance ont accordé des entrevues individuelles semi-dirigées portant sur : 1) le dévoilement du statut sérologique, 2) leurs relations familiales et 3) l’éducation sexuelle en milieu familial. Les témoignages ont fait l’objet d’une analyse de contenu. RÉSULTATS : Les jeunes ont appris en moyenne à l’âge de 11 ans leur diagnostic VIH+. La dynamique qui s’installe après cette annonce apparaît régie par le silence : les échanges qui s’ensuivent portent en majorité sur des questions relatives à la médication et à la prévention d’une transmission sexuelle du virus. Ce silence préserverait l’équilibre familial en occupant trois fonctions : protéger la mère d’un sentiment de culpabilité à l’égard de la transmission, assurer l’harmonie familiale, se sentir normal face aux autres. Le diagnostic de l’adolescent n’est généralement pas révélé à la famille élargie, préservant ainsi leur intégration au sein de la famille en les protégeant du rejet, de la trahison et du jugement. EXPOSÉ : Les fonctions du silence et du secret occupent une place stabilisatrice importante au sein de la famille. Toutefois, elles contribuent à isoler les adolescents d’une forme de soutien affectif dont ils ont pourtant besoin. Des pistes d’intervention sont suggérées. PMID:22851894

The oxygen effect and adaptive response of cells. Report 3. Simulation of respiratory oxygenation and oxygen permeability of cells

International Nuclear Information System (INIS)

Ehpshtejn, I.M.

1978-01-01

Variations in the oxygen concentration in extracellural [O 2 ] 0 and intracellular [Osub(2)]sub(i) media of cells small in size (d = 2 ] 0 - t-curves). It is shown that the Value of [Osub(2)]sub(i) may be expressed by four variants of its functional dependence: (a) on enzymic reaction of oxygen consumption, (b) on the order of reaction with respect to oxygen, (c) on physiological parameters of cells, and (d) on characteristic oxygen concentrations in the system. Items (c) and (d) are based on the postulated diffusion-kinetic model of oxygen consumption by an idealized cell of small size that consists of a drop of homogenous solution of the respiratory enzyme which is characterized by an equivalent Michaelis constant. The drop is enveloped in a uniform membrane that possesses a definite diffuse resistance to oxygen

Proterozoic atmospheric oxygen

DEFF Research Database (Denmark)

Canfield, Donald Eugene

2014-01-01

This article is concerned with the evolution of atmospheric oxygen concentrations through the Proterozoic Eon. In particular, this article will seek to place the history of atmospheric oxygenation through the Proterozoic Eon in the context of the evolving physical environment including the history...... of continental growth and volcanic outgassing, as well as biogeochemical processing of elements within the oceans. The author will seek to explore constraints on the history of oxygenation and understand which processes have regulated oxygen through this eon....

Oxygen respiration rates of benthic foraminifera as measured with oxygen microsensors

DEFF Research Database (Denmark)

Geslin, E.; Risgaard-Petersen, N.; Lombard, Fabien

2011-01-01

of the foraminiferal specimens. The results show a wide range of oxygen respiration rates for the different species (from 0.09 to 5.27 nl cell−1 h−1) and a clear correlation with foraminiferal biovolume showed by the power law relationship: R = 3.98 10−3 BioVol0.88 where the oxygen respiration rate (R) is expressed......Oxygen respiration rates of benthic foraminifera are still badly known, mainly because they are difficult to measure. Oxygen respiration rates of seventeen species of benthic foraminifera were measured using microelectrodes and calculated on the basis of the oxygen fluxes measured in the vicinity...... groups (nematodes, copepods, ostracods, ciliates and flagellates) suggests that benthic foraminifera have a lower oxygen respiration rates per unit biovolume. The total contribution of benthic foraminifera to the aerobic mineralisation of organic matter is estimated for the studied areas. The results...

A model for oxygen conservation associated with titration during pediatric oxygen therapy.

Directory of Open Access Journals (Sweden)

Grace Wu

Full Text Available Continuous oxygen treatment is essential for managing children with hypoxemia, but access to oxygen in low-resource countries remains problematic. Given the high burden of pneumonia in these countries and the fact that flow can be gradually reduced as therapy progresses, oxygen conservation through routine titration warrants exploration.To determine the amount of oxygen saved via titration during oxygen therapy for children with hypoxemic pneumonia.Based on published clinical data, we developed a model of oxygen flow rates needed to manage hypoxemia, assuming recommended flow rate at start of therapy, and comparing total oxygen used with routine titration every 3 minutes or once every 24 hours versus no titration.Titration every 3 minutes or every 24 hours provided oxygen savings estimated at 11.7% ± 5.1% and 8.1% ± 5.1% (average ± standard error of the mean, n = 3, respectively. For every 100 patients, 44 or 30 kiloliters would be saved-equivalent to 733 or 500 hours at 1 liter per minute.Ongoing titration can conserve oxygen, even performed once-daily. While clinical validation is necessary, these findings could provide incentive for the routine use of pulse oximeters for patient management, as well as further development of automated systems.

Effets de l'alimentation des poissons avec Azolla sur la production d'un écosystème agro-piscicole en zones marécageuses au Rwanda

Directory of Open Access Journals (Sweden)

Kanangire, CK.

2002-01-01

Full Text Available Effects of Azolla-based Meal on the Production of an Agro-piscicultural Ecosystem in Rwanda Marshlands. Cette étude analyse les différences de caractères au niveau de la descendance des croisements interspécifiques entre Sesamum indicum L. et Ceratotheca sesamoides Endl. Les résultats obtenus montrent que l'héritabilité de la présence d'une forte pilosité sur les tiges et sur les pétioles est contrôlée par deux gènes assortis et indépendants. Les deux gènes dominants S et P confèrent aux plantes une importante pilosité sur les tiges et sur les pétioles tandis qu'un allèle dominant S-pp et ss-P confère aux plantes une pilosité respectivement abondante sur les tiges st sur les pétioles. Seuls les génotypes homozygotes sspp avec deux gènes récessifs produisent des plantes avec peu de poils sur les tiges et sur les pétioles. Les implications de ces résultats dans l'évolution de ces espèces sont discutées.

Artificial oxygen transport protein

Science.gov (United States)

Dutton, P. Leslie

2014-09-30

This invention provides heme-containing peptides capable of binding molecular oxygen at room temperature. These compounds may be useful in the absorption of molecular oxygen from molecular oxygen-containing atmospheres. Also included in the invention are methods for treating an oxygen transport deficiency in a mammal.

Aircraft Oxygen Generation

Science.gov (United States)

2012-02-01

An Oxygen Enriched Air System for the AV-8A Harrier (NADC-81198-60).” 70 Horch , T., et. al. “The F-16 Onboard Oxygen Generating System: Performance...Only and Safety Privileged). Horch , T., Miller, R., Bomar, J., Tedor, J., Holden, R., Ikels, K., & Lozano, P. (1983). The F-16 Onboard Oxygen

INFLUENCE DES TEMPERATURES OPERATIONNELLES SUR LA PERFORMANCE D’UN REFRIGERATEUR SOLAIRE A ADSORPTION QUI FONCTIONNE AVEC LE COUPLE CHARBON ACTIF-METHANOL

OpenAIRE

H SOUALMI; Z SAADI; A RAHMANI

2014-01-01

Le séchage des produits alimentaires au soleil est un moyen efficace, facile et économique pour conserver les aliments, en particulier les fruits. Le séchoir solaire est l'équipement le plus populaire pour le séchage des fruits. En raison de la nature intermittente de l'énergie solaire, le stockage de l'énergie thermique est nécessaire pour assurer un fonctionnement prolongé du séchoir. L'objectif principal de cette étude est d'évaluer l'efficacité du séchoir solaire intégré avec un lit en gr...

Construire les stratégies avec le Balanced Scorecard:vers une approche interactive du modèle de Kaplan et Norton

OpenAIRE

Gérald Naro; Denis Travaillé

2010-01-01

(VF)L’objectif de cet article est de confronter le Balanced Scorecard avec le modèle des leviers de contrôle de Simons (1995) et de discuter de son rôle dans les différentes phases du processus stratégique. Nous privilégions une représentation du BSC comme outil de contrôle interactif. Notre recherche est fondée sur une méthodologie longitudinale de type recherche action à partir de l’étude de deux cas. Les résultats montrent que le BSC crée un processus de construction collective favorisant ...

24 mars 2016 - Le Président de la Confédération suisse, Monsieur Johann Schneider-Ammann signe le livre d'or avec la Directrice générale du CERN Fabiola Gianotti.

CERN Multimedia

Brice, Maximilien

2016-01-01

Le Président de la Confédération suisse, Monsieur Johann Schneider-Ammann signe le livre d'or avec la Directrice générale du CERN Fabiola Gianotti. De g. à d.: F. Eder, Délégué aux Relations avec les Etats-hôtes; F. Bordry, Directeur des accélérateurs et de la technologie; S. E. M. l'Ambassadeur Fasel, Représentant permanent de la Suisse auprès de l’Office des Nations Unies et des autres organisations internationales à Genève; M. Steinacher, Directeur des finances et des ressources humaines et P. Pardo, Conseiller, Mission permanente de la Suisse auprès de l’Office des Nations Unies et des autres organisations internationales à Genève.

Oxygen enrichment incineration

International Nuclear Information System (INIS)

Kim, Jeong Guk; Yang, Hee Chul; Park, Geun Il; Kim, Joon Hyung

2000-10-01

Oxygen enriched combustion technology has recently been used in waste incineration. To apply the oxygen enrichment on alpha-bearing waste incineration, which is being developed, a state-of-an-art review has been performed. The use of oxygen or oxygen-enriched air instead of air in incineration would result in increase of combustion efficiency and capacity, and reduction of off-gas product. Especially, the off-gas could be reduced below a quarter, which might reduce off-gas treatment facilities, and also increase an efficiency of off-gas treatment. However, the use of oxygen might also lead to local overheating and high nitrogen oxides (NOx) formation. To overcome these problems, an application of low NOx oxy-fuel burner and recycling of a part of off-gas to combustion chamber have been suggested

Oxygen enrichment incineration

Energy Technology Data Exchange (ETDEWEB)

Kim, Jeong Guk; Yang, Hee Chul; Park, Geun Il; Kim, Joon Hyung

2000-10-01

Oxygen enriched combustion technology has recently been used in waste incineration. To apply the oxygen enrichment on alpha-bearing waste incineration, which is being developed, a state-of-an-art review has been performed. The use of oxygen or oxygen-enriched air instead of air in incineration would result in increase of combustion efficiency and capacity, and reduction of off-gas product. Especially, the off-gas could be reduced below a quarter, which might reduce off-gas treatment facilities, and also increase an efficiency of off-gas treatment. However, the use of oxygen might also lead to local overheating and high nitrogen oxides (NOx) formation. To overcome these problems, an application of low NOx oxy-fuel burner and recycling of a part of off-gas to combustion chamber have been suggested.

Effects of oxygen concentration on atmospheric pressure dielectric barrier discharge in Argon-Oxygen Mixture

Science.gov (United States)

Li, Xuechun; Li, Dian; Wang, Younian

2016-09-01

A dielectric barrier discharge (DBD) can generate a low-temperature plasma easily at atmospheric pressure and has been investigated for applications in trials in cancer therapy, sterilization, air pollution control, etc. It has been confirmed that reactive oxygen species (ROS) play a key role in the processes. In this work, we use a fluid model to simulate the plasma characteristics for DBD in argon-oxygen mixture. The effects of oxygen concentration on the plasma characteristics have been discussed. The evolution mechanism of ROS has been systematically analyzed. It was found that the ground state oxygen atoms and oxygen molecular ions are the dominated oxygen species under the considered oxygen concentrations. With the oxygen concentration increasing, the densities of electrons, argon atomic ions, resonance state argon atoms, metastable state argon atoms and excited state argon atoms all show a trend of decline. The oxygen molecular ions density is high and little influenced by the oxygen concentration. Ground state oxygen atoms density tends to increase before falling. The ozone density increases significantly. Increasing the oxygen concentration, the discharge mode begins to change gradually from the glow discharge mode to Townsend discharge mode. Project supported by the National Natural Science Foundation of China (Grant No. 11175034).

Limitations of potentiometric oxygen sensors operating at low oxygen levels

DEFF Research Database (Denmark)

Lund, Anders; Jacobsen, Torben; Hansen, Karin Vels

2011-01-01

The electrochemical processes that limit the range of oxygen partial pressures in which potentiometric oxygen sensors can be used, were analysed using a theoretical and an experimental approach. Electrochemical impedance spectroscopy was performed on porous Pt/yttria stabilised zirconia (YSZ......) electrodes between 10−6 and 0.2 bar and at temperatures between 500 and 950 °C. The flow of oxide ions and electron holes through a sensor cell, with a YSZ electrolyte, were calculated under similar conditions. The oxygen permeation of the sensor cell was insignificant at an oxygen partial pressure of 10......−6 bar for an inlet flow rate higher than 2 L h−1 between 600 and 800 °C. The polarisation resistance measured between 10−6 and 10−4 bar was found to be inversely proportional to the oxygen partial pressure, nearly temperature independent and inversely proportional to the inlet gas flow rate, which shows...

Nature of oxygen donors and radiation defects in oxygen-doped germanium

International Nuclear Information System (INIS)

Fukuoka, Noboru; Atobe, Kozo; Honda, Makoto; Matsuda, Koji.

1991-01-01

The nature of oxygen donors and radiation defects in oxygen-doped germanium were studied through measurements of the infrared absorption spectrum, deep level transient spectroscopy spectrum and carrier concentration. It is revealed that a new donor is not formed in oxygen-doped germanium. An A-center (interstitial oxygen-vacancy pair) forms a complex with a thermal donor in its annealing stage at 60degC-140degC. The introduction rate of defects by 1.5 MeV electron irradiation was enhanced in thermal-donor-doped samples. (author)

Intraportal islet oxygenation.

Science.gov (United States)

Suszynski, Thomas M; Avgoustiniatos, Efstathios S; Papas, Klearchos K

2014-05-01

Islet transplantation (IT) is a promising therapy for the treatment of diabetes. The large number of islets required to achieve insulin independence limit its cost-effectiveness and the number of patients who can be treated. It is believed that >50% of islets are lost in the immediate post-IT period. Poor oxygenation in the early post-IT period is recognized as a possible reason for islet loss and dysfunction but has not been extensively studied. Several key variables affect oxygenation in this setting, including (1) local oxygen partial pressure (pO(2)), (2) islet oxygen consumption, (3) islet size (diameter, D), and (4) presence or absence of thrombosis on the islet surface. We discuss implications of oxygen-limiting conditions on intraportal islet viability and function. Of the 4 key variables, the islet size appears to be the most important determinant of the anoxic and nonfunctional islet volume fractions. Similarly, the effect of thrombus formation on the islet surface may be substantial. At the University of Minnesota, average size distribution data from clinical alloislet preparations (n = 10) indicate that >150-µm D islets account for only ~30% of the total islet number, but >85% of the total islet volume. This suggests that improved oxygen supply to the islets may have a profound impact on islet survivability and function since most of the β-cell volume is within large islets which are most susceptible to oxygen-limiting conditions. The assumption that the liver is a suitable islet transplant site from the standpoint of oxygenation should be reconsidered. © 2014 Diabetes Technology Society.

[Correlation between the inspired fraction of oxygen, maternal partial oxygen pressure, and fetal partial oxygen pressure during cesarean section of normal pregnancies].

Science.gov (United States)

Castro, Carlos Henrique Viana de; Cruvinel, Marcos Guilherme Cunha; Carneiro, Fabiano Soares; Silva, Yerkes Pereira; Cabral, Antônio Carlos Vieira; Bessa, Roberto Cardoso

2009-01-01

Despite changes in pulmonary function, maternal oxygenation is maintained during obstetric regional blocks. But in those situations, the administration of supplementary oxygen to parturients is a common practice. Good fetal oxygenation is the main justification; however, this has not been proven. The objective of this randomized, prospective study was to test the hypothesis of whether maternal hyperoxia is correlated with an increase in fetal gasometric parameters in elective cesarean sections. Arterial blood gases of 20 parturients undergoing spinal block with different inspired fractions of oxygen were evaluated and correlated with fetal arterial blood gases. An increase in maternal inspired fraction of oxygen did not show any correlation with an increase of fetal partial oxygen pressure. Induction of maternal hyperoxia by the administration of supplementary oxygen did not increase fetal partial oxygen pressure. Fetal gasometric parameters did not change even when maternal parameters changed, induced by hyperoxia, during cesarean section under spinal block.

Evaluation of the cohesion at the early age and the mechanical properties at the cured stage of the gravel-emulsion cold mixes

OpenAIRE

GAUDEFROY, V; BEGHIN, A; PLACIN, F; BROSSEAUD, Y; DE LA ROCHE, C; DELANOE, YM

2006-01-01

La méthode de formulation enrobés bitumineux à froid tels que la grave-émulsion est basée actuellement sur les caractéristiques qui sont employées pour les enrobés à chaud. Ce n'est plus satisfaisant. Il semble nécessaire d'adopter une approche qui tient compte, après rupture de l'émulsion, de l'influence de l'eau. Le rôle actif de l'eau influent sur la montée en cohésion des mélanges bitumeux élaborés à froid. Cela se vérifie en particulier sur les propriétés comme la résistance mécanique et...

Yeast alter micro-oxygenation of wine: oxygen consumption and aldehyde production.

Science.gov (United States)

Han, Guomin; Webb, Michael R; Richter, Chandra; Parsons, Jessica; Waterhouse, Andrew L

2017-08-01

Micro-oxygenation (MOx) is a common winemaking treatment used to improve red wine color development and diminish vegetal aroma, amongst other effects. It is commonly applied to wine immediately after yeast fermentation (phase 1) or later, during aging (phase 2). Although most winemakers avoid MOx during malolactic (ML) fermentation, it is often not possible to avoid because ML bacteria are often present during phase 1 MOx treatment. We investigated the effect of common yeast and bacteria on the outcome of micro-oxygenation. Compared to sterile filtered wine, Saccharomyces cerevisiae inoculation significantly increased oxygen consumption, keeping dissolved oxygen in wine below 30 µg L -1 during micro-oxygenation, whereas Oenococcus oeni inoculation was not associated with a significant impact on the concentration of dissolved oxygen. The unfiltered baseline wine also had both present, although with much higher populations of bacteria and consumed oxygen. The yeast-treated wine yielded much higher levels of acetaldehyde, rising from 4.3 to 29 mg L -1 during micro-oxygenation, whereas no significant difference was found between the bacteria-treated wine and the filtered control. The unfiltered wine exhibited rapid oxygen consumption but no additional acetaldehyde, as well as reduced pyruvate. Analysis of the acetaldehyde-glycerol acetal levels showed a good correlation with acetaldehyde concentrations. The production of acetaldehyde is a key outcome of MOx and it is dramatically increased in the presence of yeast, although it is possibly counteracted by the metabolism of O. oeni bacteria. Additional controlled experiments are necessary to clarify the interaction of yeast and bacteria during MOx treatments. Analysis of the glycerol acetals may be useful as a proxy for acetaldehyde levels. © 2017 Society of Chemical Industry. © 2017 Society of Chemical Industry.

Oxygen configurations in silica

International Nuclear Information System (INIS)

Chelikowsky, James R.; Chadi, D. J.; Binggeli, N.

2000-01-01

We propose a transition state for oxygen in silica. This state is produced by the insertion of an oxygen molecule into the Si-O-Si bond, i.e., it consists of producing a Si-O-O-O-Si bond. This state allows molecular oxygen diffusion in silica without breaking the molecular O 2 bond and it is energetically more stable than a peroxy configuration. This configuration may allow for exchange of molecular oxygen with the oxygen in the silica framework. (c) 2000 The American Physical Society

Oxygen transport by oxygen potential gradient in dense ceramic oxide membranes

Energy Technology Data Exchange (ETDEWEB)

Maiya, P.S.; Balachandran, U.; Dusek, J.T.; Mieville, R.L. [Argonne National Lab., IL (United States). Energy Technology Div.; Kleefisch, M.S.; Udovich, C.A. [Amoco Exploration/Production, Naperville, IL (United States)

1996-05-01

Numerous studies have been conducted in recent years on the partial oxidation of methane to synthesis gas (syngas: CO + H{sub 2}) with air as the oxidant. In partial oxidation, a mixed-oxide ceramic membrane selectively transports oxygen from the air; this transport is driven by the oxygen potential gradient. Of the several ceramic materials the authors have tested, a mixed oxide based on the Sr-Fe-Co-O system has been found to be very attractive. Extensive oxygen permeability data have been obtained for this material in methane conversion experiments carried out in a reactor. The data have been analyzed by a transport equation based on the phenomenological theory of diffusion under oxygen potential gradients. Thermodynamic calculations were used to estimate the driving force for the transport of oxygen ions. The results show that the transport equation deduced from the literature describes the permeability data reasonably well and can be used to determine the diffusion coefficients and the associated activation energy of oxygen ions in the ceramic membrane material.

Comparison of domiciliary oxygen using liquid oxygen and concentrator in northern Taiwan

Directory of Open Access Journals (Sweden)

Chien-Ling Su

2014-01-01

Conclusion: Patients in the LOG used oxygen for longer hours, went on more outings, and were more likely to travel with oxygen than patients in the OCG. Being ambulatory with liquid oxygen might enable patients with COPD to walk more effectively.

Simultaneous Monitoring of Vascular Oxygenation and Tissue Oxygen Tension of Breast Tumors Under Hyperbaric Oxygen Exposure

Science.gov (United States)

2008-04-01

28. Alagoz, T., R. Buller, B. Anderson, K. Terrell , R...and oxygenation Ann . New Acad. Sci. 838 29–45 Chapman J D, Stobbe C C, Arnfield M R, Santus R, Lee J and McPhee M S 1991 Oxygen dependency of tumor

Boundary layer on a flat plate with suction; Couche limite sur paroi plane poreuse avec aspiration

Energy Technology Data Exchange (ETDEWEB)

Favre, A; Dumas, R; Verollet, E [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires; Institut de Mecanique Statistique de la Turbulence, Faculte des Sciences de Marseille, 13 (France)

1961-07-01

'une plaque plane avec aspiration. La paroi poreuse s'etend sur 1 m de longueur, a partir d'une distance de 1 m en aval du bord d'attaque. Le nombre de Reynolds d'epaisseur de la couche limite en l'absence d'aspiration est de l'ordre de 16,300. Le taux d'aspiration, defini comme le rapport a la vitesse generale de la vitesse normale a la paroi, est reglable de 0 a 2 pour cent. Le gradient de pression est controlable. On a determine en diverses positions et pour divers taux d'aspiration: avec des sondes de prise de pression totale, les profils de vitesse moyenne, avec des anemometres a fils chauds, analyseur spectral et correlateur, les intensites des differentes composantes des fluctuations turbulentes de vitesse, les spectres d'energie, les correlations. On deduit de ces mesures: le trace des lignes de courant, les valeurs des tensions de frottement visqueux et turbulent, du frottement local a la paroi, et du terme de production de l'energie turbulente, ainsi que des indications sur la dissipation de cette energie. Pour ces calculs, l'equation integree de conservations de la masse dans la couche limite a ete etablie. L'influence de l'aspiration sur la couche limite est importante: elle modifie profondement la forme des profils de vitesse moyenne, augmentant les tensions de frottement visqueux a la paroi, les diminuant ailleurs; elle diminue les intensites de turbulence longitudinale et transversale ainsi que les tensions de frottement turbulent et la production d'energie turbulente. Ces effets sont tres marques dans la zone interne de la couche limite. Par contre, l'etude des spectres d'energie indique que l'echelle de la turbulence, est peu modifiee, l'epaisseur de la couche limite ne diminuant que faiblement sous l'influence de l'aspiration. Les effets de l'aspiration peuvent etre apprecies en comparant le double du taux d'aspiration au coefficient de frottement a la paroi (supposee etanche); notables des que ce rapport depasse l'unite, ils deviennent tres importants

Sur le discours et l’histoire en foucault. Entretien avec Jacques Guilhaumou

Directory of Open Access Journals (Sweden)

Welisson Marques

2013-08-01

Full Text Available Dans cet entretien inédit, Jaques Guilhaumou parle sur la question du discours et de l´histoire dans la pensée de Michel Foucault en regardant telles questions à partir du belvédère de l’Analyse du Discours selon la perception française. Il commence en présentant un panorama de ses travaux plus actuels et souligne ensuite le rôle décisif de Foucault dans le établissement de une nouvelle relation entre le discours et l´histoire. Dans cette direction, il donne des détails sur quelques influences épistémologiques de la pensée foucaultienne qui viennent surtout de Nietzsche et Koselleck. Comme un grand étudiant de la pensée marxiste, Guilhaumou parle aussi sur le concept de l´ideologie et ses plusières métamorphoses conceptuelles dans autres champs jusqu´au moment de parler sur la question du pouvoir. Il parle quand même sur la problématique de l´analyse des images dans l´Analyse du Discours, une question favorable pour beaucoup des analystes du discours qui s´occupent avec le syncrétisme sémiotique des ses objets dans l´actualité. Enfin, il indique l´existence de une théorie du discours diluée dans la pensée du philosophe.

Accouchées avec statut sérologique VIH inconnu à Lubumbashi, RD Congo: proportion et déterminants

Science.gov (United States)

Nkoy, Albert Mwembo-Tambwe A; Kayamba, Prosper Kalenga Muenze; Donnen, Philippe; Mukalenge, Faustin Chenge; Humblet, Perrine; Dramaix, Michèle; Buekens, Pierre

2012-01-01

Introduction Beaucoup d'enfants vivant avec le VIH ont été infectés par leurs mères. Pour prévenir la transmission verticale les femmes doivent d'abord connaître leur statut sérologique VIH.L'objectif de cette étude était de déterminer la proportion de statut VIH inconnu à la naissance et d'identifier les facteurs associés. Méthodes C'est une étude transversale réalisée dans 10 structures sanitaires de Lubumbashi de Juin à Septembre 2010. La taille de l’échantillon était de 602 accouchées. Les statistiques descriptives usuelles et la régression logistique ont été utilisées. Résultats Parmi les accouchées, 52,5% ignoraient leur statut sérologique. Parmi elles, 62,9% accepteraient de faire le test VIH à la maternité. La proportion des femmes avec un statut sérologique VIH inconnu était significativement plus élevée chez celles qui n'avaient pas suivi de CPN (Odds Ratio ajusté (ORa) = 5,8; Intervalle de Confiance (IC) 95%: 1,7-19,8); chez celles qui avaient un bas niveau d'instruction (ORa = 1,5; IC 95%: 1,1-2,1) et chez celles qui ne savaient pas que la transmission verticale du VIH pouvaient se faire au moment de l'accouchement (ORa = 1,5; IC 95%: 1,0-2,4). Conclusion La proportion de femmes qui accouchent sans connaître leur statut sérologique au VIH est encore importante, malgré le fait que le dépistage du VIH soit proposé lors des CPN. Dans les zones à haute séroprévalence de VIH, aucune femme ne devrait accoucher sans être dépistée au VIH. Ce serait une opportunité manquée. PMID:22891083

Recombination and detachment in oxygen discharges: the role of metastable oxygen molecules

International Nuclear Information System (INIS)

Gudmundsson, J T

2004-01-01

A global (volume averaged) model of oxygen discharges is used to study the transition from a recombination dominated discharge to a detachment dominated discharge. The model includes the metastable oxygen molecules O 2 (a 1 Δ g ) and O 2 (b 1 Σ g + ) and the three Herzberg states O 2 (A 3 Σ u + , A' 3 Δ u , c 1 Σ u - ). Dissociative attachment of the oxygen molecule in the ground state O 2 ( 3 Σ g - ) and the metastable oxygen molecule O 2 (a 1 Δ g ) are the dominating channels for creation of the negative oxygen ion O - . At high pressures, dissociative attachment of the Herzberg states contributes significantly to the creation of the negative oxygen ion, O - . The detachment by a collision of the metastable oxygen molecule O 2 (b 1 Σ g + ) with the oxygen ion, O - , is a significant loss process for the O - at pressures above 10 mTorr. Its contribution to the loss is more significant at a lower applied power, but at the higher pressures it is always significant. Detachment by collision with O( 3 P) is also an important loss mechanism for O - . We find that ion-ion recombination is the dominating loss process for negative ions in oxygen discharges at low pressures and calculate the critical pressure where the contributions of recombination reactions and detachment reactions are equal. This critical pressure depends on the applied power, increases with applied power and is in the range 5-14 mTorr in the pressure and power range investigated

Effect of hypolimnetic oxygenation on oxygen depletion rates in two water-supply reservoirs.

Science.gov (United States)

Gantzer, Paul A; Bryant, Lee D; Little, John C

2009-04-01

Oxygenation systems, such as bubble-plume diffusers, are used to improve water quality by replenishing dissolved oxygen (DO) in the hypolimnia of water-supply reservoirs. The diffusers induce circulation and mixing, which helps distribute DO throughout the hypolimnion. Mixing, however, has also been observed to increase hypolimnetic oxygen demand (HOD) during system operation, thus accelerating oxygen depletion. Two water-supply reservoirs (Spring Hollow Reservoir (SHR) and Carvins Cove Reservoir (CCR)) that employ linear bubble-plume diffusers were studied to quantify diffuser effects on HOD. A recently validated plume model was used to predict oxygen addition rates. The results were used together with observed oxygen accumulation rates to evaluate HOD over a wide range of applied gas flow rates. Plume-induced mixing correlated well with applied gas flow rate and was observed to increase HOD. Linear relationships between applied gas flow rate and HOD were found for both SHR and CCR. HOD was also observed to be independent of bulk hypolimnion oxygen concentration, indicating that HOD is controlled by induced mixing. Despite transient increases in HOD, oxygenation caused an overall decrease in background HOD, as well as a decrease in induced HOD during diffuser operation, over several years. This suggests that the residual or background oxygen demand decreases from one year to the next. Despite diffuser-induced increases in HOD, hypolimnetic oxygenation remains a viable method for replenishing DO in thermally-stratified water-supply reservoirs such as SHR and CCR.

Spray generator of singlet oxygen for a chemical oxygen-iodine laser

Czech Academy of Sciences Publication Activity Database

Jirásek, Vít; Hrubý, Jan; Špalek, Otomar; Čenský, Miroslav; Kodymová, Jarmila

2010-01-01

Roč. 100, č. 4 (2010), s. 779-791 ISSN 0946-2171 Grant - others:European Office of Aerospace R&D(US) FA8655-09-1-3091 Institutional research plan: CEZ:AV0Z10100523; CEZ:AV0Z20760514 Keywords : spray generator of singlet oxygen * singlet oxygen * chemical oxygen-iodine laser Subject RIV: BH - Optics, Masers, Lasers Impact factor: 2.239, year: 2010

Effects of the oxygenation level on formation of different reactive oxygen species during photodynamic therapy.

Science.gov (United States)

Price, Michael; Heilbrun, Lance; Kessel, David

2013-01-01

We examined the effect of the oxygenation level on efficacy of two photosensitizing agents, both of which target lysosomes for photodamage, but via different photochemical pathways. Upon irradiation, the chlorin termed NPe6 forms singlet oxygen in high yield while the bacteriopheophorbide WST11 forms only oxygen radicals (in an aqueous environment). Photokilling efficacy by WST11 in cell culture was impaired when the atmospheric oxygen concentration was reduced from 20% to 1%, while photokilling by NPe6 was unaffected. Studies in a cell-free system revealed that the rates of photobleaching of these agents, as a function of the oxygenation level, were correlated with results described above. Moreover, the rate of formation of oxygen radicals by either agent was more sensitive to the level of oxygenation than was singlet oxygen formation by NPe6. These data indicate that the photochemical process that leads to oxygen radical formation is more dependent on the oxygenation level than is the pathway leading to formation of singlet oxygen. © 2013 Wiley Periodicals, Inc. Photochemistry and Photobiology © 2013 The American Society of Photobiology.

Advanced Oxygen Systems for Aircraft (Systemes d’Oxygene Avances)

Science.gov (United States)

1996-04-01

Oxygen Generating System (NAOGS), SAM-TR-80-12, Brooks AFB TX 78235, 1980. 11. Horch TC, Miller RL, Bomar JB, Tedor JB, Holden RD, Ikels KG, and...sieve oxygen generation sys- tem. Data from Horch et al (15). cabin altitude. The minimum and maximum oxygen concen- tration lines depict the...an AV-8A Aircraft; Naval Air Test Center Report No. SY-136R-81, 1981. 15. Horch TC, Miller RL, Bomar JB Jr, Tedor JB, Holden RD, Ikels KG, and

Kinetics of oxygen species in an electrically driven singlet oxygen generator

Science.gov (United States)

Azyazov, V. N.; Torbin, A. P.; Pershin, A. A.; Mikheyev, P. A.; Heaven, M. C.

2015-12-01

The kinetics of oxygen species in the gaseous medium of a discharge singlet oxygen generator has been revisited. Vibrationally excited ozone O3(υ) formed in O + O2 recombination is thought to be a significant agent in the deactivation of singlet oxygen O2(a1Δ), oxygen atom removal and ozone formation. It is shown that the process O3(υ ⩾ 2) + O2(a1Δ) → 2O2 + O is the main O2(a1Δ) deactivation channel in the post-discharge zone. If no measures are taken to decrease the oxygen atom concentration, the contribution of this process to the overall O2(a1Δ) removal is significant, even in the discharge zone. A simplified model for the kinetics of vibrationally excited ozone is proposed. Calculations based on this model yield results that are in good agreement with the experimental data.

Oxygen therapy reduces postoperative tachycardia

DEFF Research Database (Denmark)

Stausholm, K; Kehlet, H; Rosenberg, J

1995-01-01

Concomitant hypoxaemia and tachycardia in the postoperative period is unfavourable for the myocardium. Since hypoxaemia per se may be involved in the pathogenesis of postoperative tachycardia, we have studied the effect of oxygen therapy on tachycardia in 12 patients randomly allocated to blinded...... air or oxygen by facemask on the second or third day after major surgery. Inclusion criteria were arterial hypoxaemia (oxygen saturation 90 beat.min-1). Each patient responded similarly to oxygen therapy: an increase in arterial oxygen saturation and a decrease...... in heart rate (p oxygen has a positive effect on the cardiac oxygen delivery and demand balance....

Dependence of nitrite oxidation on nitrite and oxygen in low-oxygen seawater

Science.gov (United States)

Sun, Xin; Ji, Qixing; Jayakumar, Amal; Ward, Bess B.

2017-08-01

Nitrite oxidation is an essential step in transformations of fixed nitrogen. The physiology of nitrite oxidizing bacteria (NOB) implies that the rates of nitrite oxidation should be controlled by concentration of their substrate, nitrite, and the terminal electron acceptor, oxygen. The sensitivities of nitrite oxidation to oxygen and nitrite concentrations were investigated using 15N tracer incubations in the Eastern Tropical North Pacific. Nitrite stimulated nitrite oxidation under low in situ nitrite conditions, following Michaelis-Menten kinetics, indicating that nitrite was the limiting substrate. The nitrite half-saturation constant (Ks = 0.254 ± 0.161 μM) was 1-3 orders of magnitude lower than in cultivated NOB, indicating higher affinity of marine NOB for nitrite. The highest rates of nitrite oxidation were measured in the oxygen depleted zone (ODZ), and were partially inhibited by additions of oxygen. This oxygen sensitivity suggests that ODZ specialist NOB, adapted to low-oxygen conditions, are responsible for apparently anaerobic nitrite oxidation.

Hyperbaric Oxygen Therapy and Oxygen Compatibility of Skin and Wound Care Products.

Science.gov (United States)

Bernatchez, Stéphanie F; Tucker, Joseph; Chiffoleau, Gwenael

2017-11-01

Objective: Use test methods to assess the oxygen compatibility of various wound care products. Approach: There are currently no standard test methods specifically for evaluating the oxygen compatibility and safety of materials under hyperbaric oxygen (HBO) conditions. However, tests such as the oxygen index (OI), oxygen exposure (OE), and autogenous ignition temperature (AIT) can provide useful information. Results: The OI test measures the minimum oxygen concentration that will support candle-like burning, and it was used to test 44 materials. All but two exhibited an OI equal to or greater (safer) than a control material commonly used in HBO. The OE test exposes each material to an oxygen-enriched atmosphere (>99.5% oxygen) to monitor temperature and pressure for an extended duration. The results of the OE testing indicated that none of the 44 articles tested with this method self-ignited within the 60°C, 3 atm pressurized oxygen atmosphere. The AIT test exposes materials to a rapid ramp up in temperature in HBO conditions at 3 atm until ignition occurs. Ten wound care materials and seven materials usually avoided in HBO chambers were tested. The AIT ranged from 138°C to 384°C for wound care products and from 146°C to 420°C for the other materials. Innovation: This work provides useful data and recommendations to help develop a new standard approach for evaluating the HBO compatibility of wound care products to ensure safety for patients and clinicians. Conclusion: The development of an additional test to measure the risk of electrostatic discharge of materials in HBO conditions is needed.

Oxygen transfer rate during the production of alginate by Azotobacter vinelandii under oxygen-limited and non oxygen-limited conditions

Directory of Open Access Journals (Sweden)

Peña Carlos F

2011-02-01

Full Text Available Abstract Background The oxygen transfer rate (OTR and dissolved oxygen tension (DOT play an important role in determining alginate production and its composition; however, no systematic study has been reported about the independent influence of the OTR and DOT. In this paper, we report a study about alginate production and the evolution of the molecular mass of the polymer produced by a wild-type A. vinelandii strain ATCC 9046, in terms of the maximum oxygen transfer rate (OTRmax in cultures where the dissolved oxygen tension (DOT was kept constant. Results The results revealed that in the two dissolved oxygen conditions evaluated, strictly controlled by gas blending at 0.5 and 5% DOT, an increase in the agitation rate (from 300 to 700 rpm caused a significant increase in the OTRmax (from 17 to 100 mmol L-1 h-1 for DOT of 5% and from 6 to 70 mmol L-1 h-1 for DOT of 0.5%. This increase in the OTRmax improved alginate production, as well as the specific alginate production rate (SAPR, reaching a maximal alginate concentration of 3.1 g L-1 and a SAPR of 0.031 g alg g biom-1 h-1 in the cultures at OTRmax of 100 mmol L-1 h-1. In contrast, the mean molecular mass (MMM of the alginate isolated from cultures developed under non-oxygen limited conditions increased by decreasing the OTRmax, reaching a maximal of 550 kDa at an OTRmax of 17 mmol L-1 h-1 . However, in the cultures developed under oxygen limitation (0.5% DOT, the MMM of the polymer was practically the same (around 200 kDa at 300 and 700 rpm, and this remained constant throughout the cultivation. Conclusions Overall, our results showed that under oxygen-limited and non oxygen-limited conditions, alginate production and its molecular mass are linked to the OTRmax, independently of the DOT of the culture.

A theoretical model for oxygen transport in skeletal muscle under conditions of high oxygen demand.

Science.gov (United States)

McGuire, B J; Secomb, T W

2001-11-01

Oxygen transport from capillaries to exercising skeletal muscle is studied by use of a Krogh-type cylinder model. The goal is to predict oxygen consumption under conditions of high demand, on the basis of a consideration of transport processes occurring at the microvascular level. Effects of the decline in oxygen content of blood flowing along capillaries, intravascular resistance to oxygen diffusion, and myoglobin-facilitated diffusion are included. Parameter values are based on human skeletal muscle. The dependence of oxygen consumption on oxygen demand, perfusion, and capillary density are examined. When demand is moderate, the tissue is well oxygenated and consumption is slightly less than demand. When demand is high, capillary oxygen content declines rapidly with axial distance and radial oxygen transport is limited by diffusion resistance within the capillary and the tissue. Under these conditions, much of the tissue is hypoxic, consumption is substantially less than demand, and consumption is strongly dependent on capillary density. Predicted consumption rates are comparable with experimentally observed maximal rates of oxygen consumption.

Oxygen-transfer performance of a newly designed, very low-volume membrane oxygenator.

Science.gov (United States)

Burn, Felice; Ciocan, Sorin; Carmona, Natalia Mendez; Berner, Marion; Sourdon, Joevin; Carrel, Thierry P; Tevaearai Stahel, Hendrik T; Longnus, Sarah L

2015-09-01

Oxygenation of blood and other physiological solutions are routinely required in fundamental research for both in vitro and in vivo experimentation. However, very few oxygenators with suitable priming volumes (parallel-oriented microporous polypropylene hollow fibres, placed inside a hollow shell with a lateral-luer outlet, and sealed at both extremities. With this design, perfusate is delivered via the core-tube to the centre of the mini-oxygenator, and exits via the luer port. A series of mini-oxygenators were constructed and tested in an in vitro perfusion circuit by monitoring oxygen transfer using modified Krebs-Henseleit buffer or whole porcine blood. Effects of perfusion pressure and temperature over flows of 5-60 ml × min(-1) were assessed. Twelve mini-oxygenators with a mean priming volume of 1.5 ± 0.3 ml were evaluated. With buffer, oxygen transfer reached a maximum of 14.8 ± 1.0 ml O2 × l(-1) (pO2: 450 ± 32 mmHg) at perfusate flow rates of 5 ml × min(-1) and decreased with an increase in perfusate flow to 7.8 ± 0.7 ml ml O2 × l(-1) (pO2: 219 ± 24 mmHg) at 60 ml × min(-1). Similarly, with blood perfusate, oxygen transfer also decreased as perfusate flow increased, ranging from 33 ± 5 ml O2 × l(-1) at 5 ml × min(-1) to 11 ± 2 ml O2 × l(-1) at 60 ml × min(-1). Furthermore, oxygen transfer capacity remained stable with blood perfusion over a period of at least 2 h. We have developed a new miniaturized membrane oxygenator with an ultra-low priming volume (circuits, such as small animal extracorporeal circulation and ex vivo organ perfusion. © The Author 2015. Published by Oxford University Press on behalf of the European Association for Cardio-Thoracic Surgery. All rights reserved.

Carbon mineralization and oxygen dynamics in sediments with deep oxygen penetration, Lake Superior

DEFF Research Database (Denmark)

Li, Jiying; Crowe, Sean Andrew; Miklesh, David

2012-01-01

To understand carbon and oxygen dynamics in sediments with deep oxygen penetration, we investigated eight locations (160–318-m depth) throughout Lake Superior. Despite the 2–4 weight percent organic carbon content, oxygen penetrated into the sediment by 3.5 to > 12 cm at all locations. Such deep ...... volume-specific carbon degradation rates were 0.3–1.5 µmol cm−3 d−1; bioturbation coefficient near the sediment surface was 3–8 cm2 yr−1. These results indicate that carbon cycling in large freshwater systems conforms to many of the same trends as in marine systems.......To understand carbon and oxygen dynamics in sediments with deep oxygen penetration, we investigated eight locations (160–318-m depth) throughout Lake Superior. Despite the 2–4 weight percent organic carbon content, oxygen penetrated into the sediment by 3.5 to > 12 cm at all locations. Such deep......, suggesting that temporal variability in deeply oxygenated sediments may be greater than previously acknowledged. The oxygen uptake rates (4.4–7.7 mmol m−2 d−1, average 6.1 mmol m−2 d−1) and carbon mineralization efficiency (∼ 90% of deposited carbon) were similar to those in marine hemipelagic and pelagic...

Spatially monitoring oxygen level in 3D microfabricated cell culture systems using optical oxygen sensing beads.

Science.gov (United States)

Wang, Lin; Acosta, Miguel A; Leach, Jennie B; Carrier, Rebecca L

2013-04-21

Capability of measuring and monitoring local oxygen concentration at the single cell level (tens of microns scale) is often desirable but difficult to achieve in cell culture. In this study, biocompatible oxygen sensing beads were prepared and tested for their potential for real-time monitoring and mapping of local oxygen concentration in 3D micro-patterned cell culture systems. Each oxygen sensing bead is composed of a silica core loaded with both an oxygen sensitive Ru(Ph2phen3)Cl2 dye and oxygen insensitive Nile blue reference dye, and a poly-dimethylsiloxane (PDMS) shell rendering biocompatibility. Human intestinal epithelial Caco-2 cells were cultivated on a series of PDMS and type I collagen based substrates patterned with micro-well arrays for 3 or 7 days, and then brought into contact with oxygen sensing beads. Using an image analysis algorithm to convert florescence intensity of beads to partial oxygen pressure in the culture system, tens of microns-size oxygen sensing beads enabled the spatial measurement of local oxygen concentration in the microfabricated system. Results generally indicated lower oxygen level inside wells than on top of wells, and local oxygen level dependence on structural features of cell culture surfaces. Interestingly, chemical composition of cell culture substrates also appeared to affect oxygen level, with type-I collagen based cell culture systems having lower oxygen concentration compared to PDMS based cell culture systems. In general, results suggest that oxygen sensing beads can be utilized to achieve real-time and local monitoring of micro-environment oxygen level in 3D microfabricated cell culture systems.

Oxygen evolution reaction catalysis

Energy Technology Data Exchange (ETDEWEB)

Haber, Joel A.; Jin, Jian; Xiang, Chengxiang; Gregoire, John M.; Jones, Ryan J.; Guevarra, Dan W.; Shinde, Aniketa A.

2016-09-06

An Oxygen Evolution Reaction (OER) catalyst includes a metal oxide that includes oxygen, cerium, and one or more second metals. In some instances, the cerium is 10 to 80 molar % of the metals in the metal oxide and/or the catalyst includes two or more second metals. The OER catalyst can be included in or on an electrode. The electrode can be arranged in an oxygen evolution system such that the Oxygen Evolution Reaction occurs at the electrode.

Relating oxygen partial pressure, saturation and content: the haemoglobin-oxygen dissociation curve.

Science.gov (United States)

Collins, Julie-Ann; Rudenski, Aram; Gibson, John; Howard, Luke; O'Driscoll, Ronan

2015-09-01

The delivery of oxygen by arterial blood to the tissues of the body has a number of critical determinants including blood oxygen concentration (content), saturation (S O2 ) and partial pressure, haemoglobin concentration and cardiac output, including its distribution. The haemoglobin-oxygen dissociation curve, a graphical representation of the relationship between oxygen satur-ation and oxygen partial pressure helps us to understand some of the principles underpinning this process. Historically this curve was derived from very limited data based on blood samples from small numbers of healthy subjects which were manipulated in vitro and ultimately determined by equations such as those described by Severinghaus in 1979. In a study of 3524 clinical specimens, we found that this equation estimated the S O2 in blood from patients with normal pH and S O2 >70% with remarkable accuracy and, to our knowledge, this is the first large-scale validation of this equation using clinical samples. Oxygen saturation by pulse oximetry (S pO2 ) is nowadays the standard clinical method for assessing arterial oxygen saturation, providing a convenient, pain-free means of continuously assessing oxygenation, provided the interpreting clinician is aware of important limitations. The use of pulse oximetry reduces the need for arterial blood gas analysis (S aO2 ) as many patients who are not at risk of hypercapnic respiratory failure or metabolic acidosis and have acceptable S pO2 do not necessarily require blood gas analysis. While arterial sampling remains the gold-standard method of assessing ventilation and oxygenation, in those patients in whom blood gas analysis is indicated, arterialised capillary samples also have a valuable role in patient care. The clinical role of venous blood gases however remains less well defined.

Relating oxygen partial pressure, saturation and content: the haemoglobin–oxygen dissociation curve

Directory of Open Access Journals (Sweden)

Julie-Ann Collins

2015-09-01

The delivery of oxygen by arterial blood to the tissues of the body has a number of critical determinants including blood oxygen concentration (content, saturation (SO2 and partial pressure, haemoglobin concentration and cardiac output, including its distribution. The haemoglobin–oxygen dissociation curve, a graphical representation of the relationship between oxygen satur­ation and oxygen partial pressure helps us to understand some of the principles underpinning this process. Historically this curve was derived from very limited data based on blood samples from small numbers of healthy subjects which were manipulated in vitro and ultimately determined by equations such as those described by Severinghaus in 1979. In a study of 3524 clinical specimens, we found that this equation estimated the SO2 in blood from patients with normal pH and SO2 >70% with remarkable accuracy and, to our knowledge, this is the first large-scale validation of this equation using clinical samples. Oxygen saturation by pulse oximetry (SpO2 is nowadays the standard clinical method for assessing arterial oxygen saturation, providing a convenient, pain-free means of continuously assessing oxygenation, provided the interpreting clinician is aware of important limitations. The use of pulse oximetry reduces the need for arterial blood gas analysis (SaO2 as many patients who are not at risk of hypercapnic respiratory failure or metabolic acidosis and have acceptable SpO2 do not necessarily require blood gas analysis. While arterial sampling remains the gold-standard method of assessing ventilation and oxygenation, in those patients in whom blood gas analysis is indicated, arterialised capillary samples also have a valuable role in patient care. The clinical role of venous blood gases however remains less well defined.

Integrated turbomachine oxygen plant

Science.gov (United States)

Anand, Ashok Kumar; DePuy, Richard Anthony; Muthaiah, Veerappan

2014-06-17

An integrated turbomachine oxygen plant includes a turbomachine and an air separation unit. One or more compressor pathways flow compressed air from a compressor through one or more of a combustor and a turbine expander to cool the combustor and/or the turbine expander. An air separation unit is operably connected to the one or more compressor pathways and is configured to separate the compressed air into oxygen and oxygen-depleted air. A method of air separation in an integrated turbomachine oxygen plant includes compressing a flow of air in a compressor of a turbomachine. The compressed flow of air is flowed through one or more of a combustor and a turbine expander of the turbomachine to cool the combustor and/or the turbine expander. The compressed flow of air is directed to an air separation unit and is separated into oxygen and oxygen-depleted air.

Oxygen sensitive polymeric nanocapsules for optical dissolved oxygen sensors

Science.gov (United States)

Sun, Zhijuan; Cai, Chenxin; Guo, Fei; Ye, Changhuai; Luo, Yingwu; Ye, Shuming; Luo, Jianchao; Zhu, Fan; Jiang, Chunyue

2018-04-01

Immobilization of the oxygen-sensitive probes (OSPs) in the host matrix greatly impacts the performance and long-term usage of the optical dissolved oxygen (DO) sensors. In this work, fluorescent dyes, as the OSPs, were encapsulated with a crosslinked fluorinated polymer shell by interfacial confined reversible addition fragmentation chain transfer miniemulsion polymerization to fabricate oxygen sensitive polymeric nanocapsules (NCs). The location of fluorescent dyes and the fluorescent properties of the NCs were fully characterized by fourier transform infrared spectrometer, x-ray photoelectron spectrometer and fluorescent spectrum. Dye-encapsulated capacity can be precisely tuned from 0 to 1.3 wt% without self-quenching of the fluorescent dye. The crosslinked fluorinated polymer shell is not only extremely high gas permeability, but also prevents the fluorescent dyes from leakage in aqueous as well as in various organic solvents, such as ethanol, acetone and tetrahydrofuran (THF). An optical DO sensor based on the oxygen sensitive NCs was fabricated, showing high sensitivity, short response time, full reversibility, and long-term operational stability of online monitoring DO. The sensitivity of the optical DO sensor is 7.02 (the ratio of the response value in fully deoxygenated and saturated oxygenated water) in the range 0.96-14.16 mg l-1 and the response time is about 14.3 s. The sensor’s work curve was fit well using the modified Stern-Volmer equation by two-site model, and its response values are hardly affected by pH ranging from 2 to 12 and keep constant during continuous measurement for 3 months. It is believed that the oxygen sensitive polymeric NCs-based optical DO sensor could be particularly useful in long-term online DO monitoring in both aqueous and organic solvent systems.

Effects of motexafin gadolinium on tumor oxygenation and cellular oxygen consumption

International Nuclear Information System (INIS)

Donnelly, E.T.; Liu, Y.; Rockwell, S.; Magda, D.

2003-01-01

Full text: Recent work in our laboratory showed that motexafin gadolinium (MGd, Xcytrin), a drug currently in Phase III clinical trials as an adjuvant to radiation therapy, modulates the oxygen tensions in EMT6 tumors. The median pO 2 increased from the control value of 1.5±0.4 mmHg to 7.4 ± 3.8 mmHg six hours after treatment with 40 μmol/kg MGd and the percentage of severely hypoxic readings in the tumors ( 7 plateau phase EMT6 cells in 3 mL Dulbecco's Modified Eagle's Medium supplemented with 10% dialyzed fetal bovine serum, which contains no ascorbic acid. In the absence of ascorbic acid, 100 μM MGd did not alter the cellular oxygen consumption rate for EMT6 cells significantly. Marked inhibition of cellular oxygen consumption was observed when cells were incubated with 100 μM MGd in medium supplemented with equimolar ascorbic acid (a 31.5% decrease in consumption was observed after 6 hours of treatment). The 5% mannitol vehicle solution with equimolar ascorbic acid had no discernible effect on cellular oxygen consumption. Ascorbic acid may facilitate cellular uptake of MGd via the intermediate formation of a MGd-oxalate complex. These studies suggest that changes in cellular oxygen consumption could contribute to the changes in tumor oxygenation seen after administration of MGd. These experiments were supported by Pharmacyclics and training grant T32CA09085 from the NIH (E.T.D.). We thank Dr. Raymond Russell for allowing us to use his oxygen electrode apparatus

Chemical Looping Combustion with Different Types of Liquid Fuels Combustion en boucle chimique avec différentes charges liquides

Directory of Open Access Journals (Sweden)

Hoteit A.

2011-02-01

Full Text Available CLC is a new promising combustion process for CO2 capture with less or even no energy penalty compared to other processes. Up to now, most of the work performed on CLC was conducted with gaseous or solid fuels, using methane and coal and/or pet coke. Liquid fuels such as heavy fuels resulting from oil distillation or conversion may also be interesting feedstocks to consider. However, liquid fuels are challenging feedstock to deal with in fluidized beds. The objective of the present work is therefore to investigate the feasibility of liquid feed injection and contact with oxygen carrier in CLC conditions in order to conduct partial or complete combustion of hydrocarbons. A batch experimental fluidized bed set-up was developed to contact alternatively oxygen carrier with liquid fuels or air. The 20 mm i.d. fluidized bed reactor was filled up with 45 g of NiAl0.44O1.67 and pulses of 1-2 g of liquid were injected in the bed at high temperatures up to 950˚C. Different feedstocks have been injected, from dodecane to heavy fuel oils No.2. Results show that, during the reduction period, it is possible to convert all the fuel injected and there is no coke remaining on particles at the end of the reduction step. Depending upon oxygen available in the bed, either full combustion or partial combustion can be achieved. Similar results were found with different liquid feeds, despite their different composition and properties. Le CLC est un nouveau concept prometteur appliqué à la combustion qui permet le captage de CO en minimisant la pénalité énergétique liée au captage. Jusqu’à présent, l’essentiel des travaux de recherche dans le domaine du CLC concerne les charges gazeuses (méthane et solides (charbon et coke. Les charges liquides, et particulièrement les résidus pétroliers, sont des charges également intéressantes à considérer a priori. La mise en oeuvre de ces charges en lit fluidisé est cependant délicate. L’objet de ce

Internal-reference solid-electrolyte oxygen sensor

International Nuclear Information System (INIS)

Haaland, D.M.

1977-01-01

A new solid-electrolyte oxygen sensor has been developed that eliminates the conventional oxygen reference in previous solid-electrolyte oxygen sensor designs and is, therefore, ideally suited as an insertion device for remote oxygen monitoring applications. It is constructed with two cells of stabilized zirconia sealed into a small unit using a new high-temperature platinum-zirconia seal. One electrochemical cell monitors the ratio of oxygen partial pressures inside and outside the sensor while the other solid-electrolyte cell is used for quantitative electrochemical pumping of oxygen. The internal oxygen reference is generated by initially pumping all oxygen out of the known internal volume of the sensor and then quantitatively pumping oxygen back in until oxygen partial pressures are equal inside and out. This information is used with the ideal gas law to calculate oxygen partial pressures. Tests were conducted from 400 to 1000 0 C in mixtures of oxygen and nitrogen spanning approximately 0.2 to 21 percent oxygen concentration range. Sensors with sputtered platinum and porous platinum paste electrodes were compared

Comportement des pots catalytiques en présence de carburants oxygénés Behavior of Catalytic Mufflers in the Presence of Oxygenated Fuels

Directory of Open Access Journals (Sweden)

Degobert P.

2006-11-01

Full Text Available A partir d'un examen critique de la bibliographie disponible, et après un rappel des répercussions sur les émissions de la présence d'alcools dans les carburants, sont successivement examinées les performances d'épurateurs catalytiques multifonctionnels ou d'oxydation appliqués à des véhicules alimentés avec des carburants dont les teneurs en produits oxygénés varient entre 10 et 100 %. Les performances des catalyseurs s'écartent peu de celles constatées dans le cas de l'essence. Elles restent très bonnes vis-à-vis des polluants non réglementés. Par ailleurs, le pot catalytique n'engendre pas, dans ses conditions normales de fonctionnement, de polluants supplémentaires caractéristiques des combustibles oxygènes utilisés. Based on a critical examination of the literature available and after a review of the effects of the presence of alcools in fuels on emissions, this article successively examines the performances of multifunctional or oxidation catalytic scrubbers applied to vehicles fed with fuels containing between 10 and 100% oxygenated products. The performances of catalysts are not very different from those found with gasoline. They remain very good with regard to pollutants not covered by regulations. Furthermore, under normal operating conditions, a catalytic muffler does not produce any supplementary pollutants characteristic of the oxygenated fuels used.

Non-self-sustained electric discharge in oxygen gas mixtures: singlet delta oxygen production

CERN Document Server

Ionin, A A; Kotkov, A A; Kochetov, I V; Napartovich, A P; Seleznev, L V; Sinitsyn, D V; Hager, G D

2003-01-01

The possibility of obtaining a high specific input energy in an electron-beam sustained discharge ignited in oxygen gas mixtures O sub 2 : Ar : CO (or H sub 2) at the total gas pressures of 10-100 Torr was experimentally demonstrated. The specific input energy per molecular component exceeded approx 6 kJ l sup - sup 1 atm sup - sup 1 (150 kJ mol sup - sup 1) as a small amount of carbon monoxide was added into a gas mixture of oxygen and argon. It was theoretically demonstrated that one might expect to obtain a singlet delta oxygen yield of 25% exceeding its threshold value needed for an oxygen-iodine laser operation at room temperature, when maintaining a non-self-sustained discharge in oxygen gas mixtures with molecular additives CO, H sub 2 or D sub 2. The efficiency of singlet delta oxygen production can be as high as 40%.

Ambient oxygen promotes tumorigenesis.

Directory of Open Access Journals (Sweden)

Ho Joong Sung

2011-05-01

Full Text Available Oxygen serves as an essential factor for oxidative stress, and it has been shown to be a mutagen in bacteria. While it is well established that ambient oxygen can also cause genomic instability in cultured mammalian cells, its effect on de novo tumorigenesis at the organismal level is unclear. Herein, by decreasing ambient oxygen exposure, we report a ∼50% increase in the median tumor-free survival time of p53-/- mice. In the thymus, reducing oxygen exposure decreased the levels of oxidative DNA damage and RAG recombinase, both of which are known to promote lymphomagenesis in p53-/- mice. Oxygen is further shown to be associated with genomic instability in two additional cancer models involving the APC tumor suppressor gene and chemical carcinogenesis. Together, these observations represent the first report directly testing the effect of ambient oxygen on de novo tumorigenesis and provide important physiologic evidence demonstrating its critical role in increasing genomic instability in vivo.

Oxygen Tension in the Aqueous Humor of Human Eyes under Different Oxygenation Conditions

Directory of Open Access Journals (Sweden)

Farideh Sharifipour

2013-01-01

Full Text Available Purpose: To measure oxygen tension in the aqueous humor of human eyes under different oxygenation conditions. Methods: This prospective comparative interventional case series consisted of two parts. In the first part, 120 consecutive patients scheduled for cataract surgery were randomized into group I (control group in which surgery was performed under local anesthesia inhaling 21% oxygen; group II in whom general anesthesia using 50% oxygen was employed; and group III receiving general anesthesia with 100% oxygen. After aspirating 0.2 ml aqueous humor under sterile conditions, the aqueous sample and a simultaneously drawn arterial blood sample were immediately analyzed using a blood gas analyzer. In part II the same procedures were performed in 10 patients after fitting a contact lens and patching the eye for 20 minutes (group IV and in 10 patients after transcorneal delivery of oxygen at a flow rate of 5 L/min (group V. Results: Mean aqueous PO2 in groups I, II and III was 112.3±6.2, 141.1±20.4, and 170.1±27 mmHg, respectively (P values <0.001 and mean arterial PO2 was 85.7±7.9, 184.6±46, and 379.1±75.9 mmHg, respectively (P values <0.001. Aqueous PO2 was 77.2±9.2 mmHg in group IV and 152.3±10.9 mmHg in group V (P values <0.001. There was a significant correlation between aqueous and blood PO2 (r=0.537, P<0.001. The contribution of atmospheric oxygen to aqueous PO2 was 23.7%. Conclusion: Aqueous oxygen tension is mostly dependent on the systemic circulation and in part on the atmosphere. Increasing inspiratory oxygen and transcorneal oxygen delivery both increase aqueous PO2 levels.

A Low-Pressure Oxygen Storage System for Oxygen Supply in Low-Resource Settings.

Science.gov (United States)

Rassool, Roger P; Sobott, Bryn A; Peake, David J; Mutetire, Bagayana S; Moschovis, Peter P; Black, Jim Fp

2017-12-01

Widespread access to medical oxygen would reduce global pneumonia mortality. Oxygen concentrators are one proposed solution, but they have limitations, in particular vulnerability to electricity fluctuations and failure during blackouts. The low-pressure oxygen storage system addresses these limitations in low-resource settings. This study reports testing of the system in Melbourne, Australia, and nonclinical field testing in Mbarara, Uganda. The system included a power-conditioning unit, a standard oxygen concentrator, and an oxygen store. In Melbourne, pressure and flows were monitored during cycles of filling/emptying, with forced voltage fluctuations. The bladders were tested by increasing pressure until they ruptured. In Mbarara, the system was tested by accelerated cycles of filling/emptying and then run on grid power for 30 d. The low-pressure oxygen storage system performed well, including sustaining a pressure approximately twice the standard working pressure before rupture of the outer bag. Flow of 1.2 L/min was continuously maintained to a simulated patient during 30 d on grid power, despite power failures totaling 2.9% of the total time, with durations of 1-176 min (mean 36.2, median 18.5). The low-pressure oxygen storage system was robust and durable, with accelerated testing equivalent to at least 2 y of operation revealing no visible signs of imminent failure. Despite power cuts, the system continuously provided oxygen, equivalent to the treatment of one child, for 30 d under typical power conditions for sub-Saharan Africa. The low-pressure oxygen storage system is ready for clinical field trials. Copyright © 2017 by Daedalus Enterprises.

Multivariate Generalized Linear Mixed Models with High Complexity / Modèles linéaires généralisés mixtes multivariés avec complexité élevée

DEFF Research Database (Denmark)

Labouriau, Rodrigo

. À titre d'exemple, je présenterai quelques applications à la génétique quantitative avec complexité élevée (plusieurs centaines de milliers d'observations et des pedigrees profonds). Dans toutes les applications présentées, il est essentiel de comprendre le processus stochastique sous-jacent associé...

Simultaneous sampling of tissue oxygenation and oxygen consumption in skeletal muscle.

Science.gov (United States)

Nugent, William H; Song, Bjorn K; Pittman, Roland N; Golub, Aleksander S

2016-05-01

Under physiologic conditions, microvascular oxygen delivery appears to be well matched to oxygen consumption in respiring tissues. We present a technique to measure interstitial oxygen tension (PISFO2) and oxygen consumption (VO2) under steady-state conditions, as well as during the transitions from rest to activity and back. Phosphorescence Quenching Microscopy (PQM) was employed with pneumatic compression cycling to achieve 1 to 10 Hz sampling rates of interstitial PO2 and simultaneous recurrent sampling of VO2 (3/min) in the exteriorized rat spinotrapezius muscle. The compression pressure was optimized to 120-130 mmHg without adverse effect on the tissue preparation. A cycle of 5s compression followed by 15s recovery yielded a resting VO2 of 0.98 ± 0.03 ml O2/100 cm(3)min while preserving microvascular oxygen delivery. The measurement system was then used to assess VO2 dependence on PISFO2 at rest and further tested under conditions of isometric muscle contraction to demonstrate a robust ability to monitor the on-kinetics of tissue respiration and the compensatory changes in PISFO2 during contraction and recovery. The temporal and spatial resolution of this approach is well suited to studies seeking to characterize microvascular oxygen supply and demand in thin tissues. Copyright © 2015 Elsevier Inc. All rights reserved.

Kinetics of oxygen species in an electrically driven singlet oxygen generator

International Nuclear Information System (INIS)

Azyazov, V.N.; Torbin, A.P.; Pershin, A.A.; Mikheyev, P.A.; Heaven, M.C.

2015-01-01

Highlights: • Vibrational excitation of O_3 increases the rate constant for O_3 + O_2(a) → 2O_2(X) + O. • Vibrationally excited O_3 is produced by the O + O_2(X) + M → O_3 + M reaction. • Ozone concentrations are impacted by the reactions of vibrationally excited O_3. • Relevant to ozone concentrations in oxygen discharges and the upper atmosphere. - Abstract: The kinetics of oxygen species in the gaseous medium of a discharge singlet oxygen generator has been revisited. Vibrationally excited ozone O_3(υ) formed in O + O_2 recombination is thought to be a significant agent in the deactivation of singlet oxygen O_2(a"1Δ), oxygen atom removal and ozone formation. It is shown that the process O_3(υ ⩾ 2) + O_2(a"1Δ) → 2O_2 + O is the main O_2(a"1Δ) deactivation channel in the post-discharge zone. If no measures are taken to decrease the oxygen atom concentration, the contribution of this process to the overall O_2(a"1Δ) removal is significant, even in the discharge zone. A simplified model for the kinetics of vibrationally excited ozone is proposed. Calculations based on this model yield results that are in good agreement with the experimental data.

Neuroprotection of hyperbaric oxygen therapy in sub-acute traumatic brain injury: not by immediately improving cerebral oxygen saturation and oxygen partial pressure.

Science.gov (United States)

Zhou, Bao-Chun; Liu, Li-Jun; Liu, Bing

2016-09-01

Although hyperbaric oxygen (HBO) therapy can promote the recovery of neural function in patients who have suffered traumatic brain injury (TBI), the underlying mechanism is unclear. We hypothesized that hyperbaric oxygen treatment plays a neuroprotective role in TBI by increasing regional transcranial oxygen saturation (rSO 2 ) and oxygen partial pressure (PaO 2 ). To test this idea, we compared two groups: a control group with 20 healthy people and a treatment group with 40 TBI patients. The 40 patients were given 100% oxygen of HBO for 90 minutes. Changes in rSO 2 were measured. The controls were also examined for rSO 2 and PaO 2 , but received no treatment. rSO 2 levels in the patients did not differ significantly after treatment, but levels before and after treatment were significantly lower than those in the control group. PaO 2 levels were significantly decreased after the 30-minute HBO treatment. Our findings suggest that there is a disorder of oxygen metabolism in patients with sub-acute TBI. HBO does not immediately affect cerebral oxygen metabolism, and the underlying mechanism still needs to be studied in depth.

OXYGEN MANAGEMENT DURING ALCOHOLIC FERMENTATION

OpenAIRE

MOENNE VARGAS, MARÍA ISABE

2013-01-01

Oxygen additions are a common practice in winemaking, as oxygen has a positive effect in fermentative kinetics, biomass synthesis and improvement of color, structure and :flavor in treated wines. However, most oxygen additions are carried out heuristically through pump-over operations solely on a know-how basis, which is difficult to manage in terms of the exact quantity of oxygen transferred to the fermenting must. It is important to estímate the amount of oxygen added because...

Medical oxygen and air travel.

Science.gov (United States)

Lyznicki, J M; Williams, M A; Deitchman, S D; Howe, J P

2000-08-01

This report responds to a resolution that asked the American Medical Association (AMA) to take action to improve airport and airline accommodations for passengers requiring medical oxygen. Information for the report was derived from a search of the MEDLINE database and references listed in pertinent articles, as well as through communications with experts in aerospace and emergency medicine. Based on this information, the AMA Council on Scientific Affairs determined that commercial air travel exposes passengers to altitude-related hypoxia and gas expansion, which may cause some passengers to experience significant symptoms and medical complications during flight. Medical guidelines are available to help physicians evaluate and counsel potential passengers who are at increased risk of inflight hypoxemia. Supplemental oxygen may be needed for some passengers to maintain adequate tissue oxygenation and prevent hypoxemic complications. For safety and security reasons, federal regulations prohibit travelers from using their own portable oxygen system onboard commercial aircraft. Many U.S. airlines supply medical oxygen for use during flight but policies and procedures vary. Oxygen-dependent passengers must make additional arrangements for the use of supplemental oxygen in airports. Uniform standards are needed to specify procedures and equipment for the use of medical oxygen in airports and aboard commercial aircraft. Revision of federal regulations should be considered to accommodate oxygen-dependent passengers and permit them to have an uninterrupted source of oxygen from departure to destination.

Oxygen transport membrane

DEFF Research Database (Denmark)

2015-01-01

The present invention relates to a novel composite oxygen transport membrane as well as its preparation and uses thereof.......The present invention relates to a novel composite oxygen transport membrane as well as its preparation and uses thereof....

Integration of oxygen membranes for oxygen production in cement plants

DEFF Research Database (Denmark)

Puig Arnavat, Maria; Søgaard, Martin; Hjuler, Klaus

2015-01-01

The present paper describes the integration of oxygen membranes in cement plants both from an energy, exergy and economic point of view. Different configurations for oxygen enrichment of the tertiary air for combustion in the pre-calciner and full oxy-fuel combustion in both pre-calciner and kiln...

Relationship Between Cerebral Oxygenation and Hemodynamic and Oxygen Transport Parameters in Surgery for Acquired Heart Diseases

Directory of Open Access Journals (Sweden)

A. I. Lenkin

2012-01-01

Full Text Available Objective: to evaluate the relationship between cerebral oxygenation and hemodynamic and oxygen transport parameters in surgical correction of concomitant acquired heart diseases. Subjects and methods. Informed consent was received from 40 patients who required surgery because of concomitant (two or more acquired heart defects. During procedure, perioperative monitoring of oxygen transport and cerebral oxygenation was performed with the aid of PiCCO2 monitor (Pulsion Medical Systems, Germany and a Fore-Sight cerebral oximeter (CASMED, USA. Anesthesia was maintained with propofol and fen-tanyl, by monitoring the depth of anesthesia. Early postoperative intensive therapy was based on the protocol for early targeted correction of hemodynamic disorders. Oxygen transport and cerebral oxygenation parameters were estimated intraopera-tively and within 24 postoperative hours. A statistical analysis including evaluation of Spearman correlations was performed with the aid of SPSS 15.0. Results. During perfusion, there was a relationship between cerebral oximetry values and hemat-ocrit levels, and oxygen partial pressure in the venous blood. Furthermore, a negative correlation between cerebral oximetry values and blood lactate levels was found 30 minutes after initiation of extracorporeal circulation (EC. During the study, there was a positive correlation between cerebral oxygenation and values of cardiac index, central venous saturation, and oxygen delivery index. There was a negative relationship between cerebral oxygenation and extravascular lung water at the beginning of surgery and a correlation between cerebral oximetry values and oxygenation index by the end of the first 24 postoperative hours. Conclusion. The cerebral oxygenation values correlate -with the main determinants of oxygen transport during EC and after cardiac surgical procedures. Cerebral oximetry may be used in early targeted therapy for the surgical correction of acquired combined

Oxygenation measurements in head and neck cancers during hyperbaric oxygenation

International Nuclear Information System (INIS)

Becker, A.; Kuhnt, T.; Dunst, J.; Liedtke, H.; Krivokuca, A.; Bloching, M.

2002-01-01

Background: Tumor hypoxia has proven prognostic impact in head and neck cancers and is associated with poor response to radiotherapy. Hyperbaric oxygenation (HBO) offers an approach to overcome hypoxia. We have performed pO 2 measurements in selected patients with head and neck cancers under HBO to determine in how far changes in the oxygenation occur and whether a possible improvement of oxygenation parameters is maintained after HBO. Patients and Methods: Seven patients (five male, two female, age 51-63 years) with squamous cell cancers of the head and neck were investigated (six primaries, one local recurrence). The median pO 2 prior to HBO was determined with the Eppendorf histograph. Sites of measurement were enlarged cervical lymph nodes (n = 5), the primary tumor (n = 1) and local recurrence (n = 1). Patients then underwent HBO (100% O 2 at 240 kPa for 30 minutes) and the continuous changes in the oxygenation during HBO were determined with a Licox probe. Patients had HBO for 30 minutes (n = 6) to 40 minutes (n = 1). HBO was continued because the pO 2 had not reached a steady state after 30 minutes. After decompression, patients ventilated pure oxygen under normobaric conditions and the course of the pO 2 was further measured over about 15 minutes. Results: Prior to HBO, the median tumor pO 2 in the Eppendorf histography was 8.6 ± 5.4 mm Hg (range 3-19 mm Hg) and the pO 2 measured with the Licox probe was 17.3 ± 25.5 mm Hg (range 0-73 mm Hg). The pO 2 increased significantly during HBO to 550 ± 333 mm Hg (range 85-984 mm Hg, p = 0.018). All patients showed a marked increase irrespective of the oxygenation prior to HBO. The maximum pO 2 in the tumor was reached after 10-33 minutes (mean 17 minutes). After leaving the hyperbaric chamber, the pO 2 was 282 ± 196 mm Hg. All patients maintained an elevated pO 2 for further 5-25 minutes (138 ± 128 mm Hg, range 42-334 mm Hg, p = 0.028 vs the pO 2 prior to HBO). Conclusions: Hyperbaric oxygenation resulted in a

Reaction Mechanism of Calcium Hydroxide with Gaseous Hydrogen Chloride Mécanisme de réaction de l'hydroxyde de calcium avec de l'acide chlorhydrique gazeux

Directory of Open Access Journals (Sweden)

Allal K. M.

2006-12-01

Full Text Available The reduction of acid gas content in combustion or incineration flue gases can be carried out by reaction with dry, fine alkaline sorbents such as calcium oxide or calcium hydroxide. In the present work, in addition to the thermodynamic study of the different reactions involved in the dechlorination process, an experimental study to identify the reaction products by means of X-ray diffraction, electron microscopy and thermogravimetry has been carried out. It has been shown that the reaction of hydrochloric acid with hydrated lime leads to the formation of not only calcium chloride but calcium hydroxichloride. La diminution de la teneur en gaz acides dans les effluents provenant des unités de combustion ou d'incinération peut être accomplie en faisant réagir ces gaz polluants avec des absorbants alcalins tels que l'oxyde ou l'hydroxyde de calcium. Dans cet article, à l'étude thermodynamique des différentes réactions mises en jeu durant le processus de déchloruration, s'ajoute une étude expérimentale menant à l'identification des produits finaux en utilisant la diffraction X, la microscopie électronique ainsi que la thermogravimétrie. A l'issue de cette étude, il a été montré que la réaction de Ca(OH2 avec HCl entraîne la formation non seulement de CaCI2 mais aussi CaCIOH.

Kinetics of oxygen species in an electrically driven singlet oxygen generator

Energy Technology Data Exchange (ETDEWEB)

Azyazov, V.N., E-mail: azyazov@fian.smr.ru [Samara State Aerospace University, 443086 (Russian Federation); Lebedev Physical Institute of RAS, Samara 443011 (Russian Federation); Torbin, A.P.; Pershin, A.A. [Samara State Aerospace University, 443086 (Russian Federation); Lebedev Physical Institute of RAS, Samara 443011 (Russian Federation); Mikheyev, P.A., E-mail: mikheyev@fian.smr.ru [Samara State Aerospace University, 443086 (Russian Federation); Lebedev Physical Institute of RAS, Samara 443011 (Russian Federation); Heaven, M.C., E-mail: mheaven@emory.edu [Emory University, Atlanta, GA 30322 (United States)

2015-12-16

Highlights: • Vibrational excitation of O{sub 3} increases the rate constant for O{sub 3} + O{sub 2}(a) → 2O{sub 2}(X) + O. • Vibrationally excited O{sub 3} is produced by the O + O{sub 2}(X) + M → O{sub 3} + M reaction. • Ozone concentrations are impacted by the reactions of vibrationally excited O{sub 3}. • Relevant to ozone concentrations in oxygen discharges and the upper atmosphere. - Abstract: The kinetics of oxygen species in the gaseous medium of a discharge singlet oxygen generator has been revisited. Vibrationally excited ozone O{sub 3}(υ) formed in O + O{sub 2} recombination is thought to be a significant agent in the deactivation of singlet oxygen O{sub 2}(a{sup 1}Δ), oxygen atom removal and ozone formation. It is shown that the process O{sub 3}(υ ⩾ 2) + O{sub 2}(a{sup 1}Δ) → 2O{sub 2} + O is the main O{sub 2}(a{sup 1}Δ) deactivation channel in the post-discharge zone. If no measures are taken to decrease the oxygen atom concentration, the contribution of this process to the overall O{sub 2}(a{sup 1}Δ) removal is significant, even in the discharge zone. A simplified model for the kinetics of vibrationally excited ozone is proposed. Calculations based on this model yield results that are in good agreement with the experimental data.

A theoretical model for the effects of reduced hemoglobin-oxygen affinity on tumor oxygenation

International Nuclear Information System (INIS)

Kavanagh, Brian D.; Secomb, Timothy W.; Hsu, Richard; Lin, P.-S.; Venitz, Jurgen; Dewhirst, Mark W.

2002-01-01

Purpose: To develop a theoretical model for oxygen delivery to tumors, and to use the model to simulate the effects of changing the affinity of hemoglobin for oxygen on tumor oxygenation. Methods and Materials: Hemoglobin affinity is expressed in terms of P 50 , the partial pressure of oxygen (Po 2 ) at half saturation. Effects of changing P 50 on arterial Po 2 are predicted using an effective vessel approach to describe diffusive oxygen transport in the lungs, assuming fixed systemic oxygen demand and fixed blood flow rate. The decline in oxygen content of blood as it flows through normal tissue before entering the tumor region is assumed fixed. The hypoxic fraction of the tumor region is predicted using a three-dimensional simulation of diffusion from a network of vessels whose geometry is derived from observations of tumor microvasculature in the rat. Results: In air-breathing rats, predicted hypoxic fraction decreases with moderate increases in P 50 , but increases with further increases of P 50 , in agreement with previous experimental results. In rats breathing hyperoxic gases, and in humans breathing either normoxic or hyperoxic gases, increased P 50 is predicted to improve tumor oxygenation. Conclusions: The results support the administration of synthetic agents to increase P 50 during radiation treatment of tumors

Optic nerve oxygenation

DEFF Research Database (Denmark)

Stefánsson, Einar; Pedersen, Daniella Bach; Jensen, Peter Koch

2005-01-01

The oxygen tension of the optic nerve is regulated by the intraocular pressure and systemic blood pressure, the resistance in the blood vessels and oxygen consumption of the tissue. The oxygen tension is autoregulated and moderate changes in intraocular pressure or blood pressure do not affect...... the optic nerve oxygen tension. If the intraocular pressure is increased above 40 mmHg or the ocular perfusion pressure decreased below 50 mmHg the autoregulation is overwhelmed and the optic nerve becomes hypoxic. A disturbance in oxidative metabolism in the cytochromes of the optic nerve can be seen...... at similar levels of perfusion pressure. The levels of perfusion pressure that lead to optic nerve hypoxia in the laboratory correspond remarkably well to the levels that increase the risk of glaucomatous optic nerve atrophy in human glaucoma patients. The risk for progressive optic nerve atrophy in human...

Modélisation par éléments finis 3D du champ magnétostatique dans les enroulements des réactances cuirassées de grande puissance. Comparaison avec le calcul en 2D

Science.gov (United States)

Ngnegueu, Triomphant; Terme, Claude; Mailhot, Michel

1993-03-01

In this paper, the finite element method is applied for the computation of the magnetostatic field in the windings of a shell-form reactor. The modeling is carried out in 3D, using FLUX3D, a software developed at the Laboratoire d'Electrotechnique de Grenoble. The results are compared to those obtained in 2D. These calculation results are also compared to some test results. Dans cet article, nous décrivons une application de la méthode des éléments finis pour la modélisation du champ magnétostatique dans les enroulements d'une réactance cuirassée de grande puissance. La modélisation est conduite en 3D, en utilisant le logiciel FLUX3D. Les résultats du calcul sont comparés avec ceux obtenus en 2D. Quelques comparaisons sont aussi effectuées avec des résultats de mesure.

Fine structure and spectral index measurements in natural uranium - graphite lattices; Mesures fines dans des reseaux a graphite

Energy Technology Data Exchange (ETDEWEB)

Cogne, F; Journet, J [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1964-07-01

The experiments described in this report have been carried out for the most part in the critical facility MARIUS, and a few during the start up of the EDF-1 power reactor. The first part deals with the fine structure measurements made in various lattices and with their analysis. Integration over the neutron spectrum of the mono-kinetic disadvantage factor derived by the A.B.H method yields results in good agreement with the experiments. The second part deals with spectral indexes measurements (Pu/U, In/Mn) made at room temperature in MARIUS. Comparison are made of experiments with calculations using various thermalization models. Experiments carried out at higher temperatures in EDF-1 are also described. (authors) [French] Les mesures decrites dans ce rapport ont ete faites pour la plupart dans l'empilement critique MARIUS sur des reseaux a graphite-uranium naturel. Une premiere partie traite des mesures de structure fine faites dans differents reseaux et de leur interpretation. On montre en particulier qu'une integration sur le spectre d'un calcul monocinetique type A.B.H. rend bien compte des experiences. Dans une deuxieme partie, on donne les resultats de mesures d'indices de spectre Pu/U et In/Mn faites sur des reseaux froids a MARIUS et leur comparaison avec les differents modeles de calculs de thermalisation. On donne egalement les resultats de quelques mesures en temperature effectuees lors du demarrage du reacteur EDF-1. (auteurs)

Oxygen and animal evolution: Did a rise of atmospheric oxygen trigger the origin of animals?

DEFF Research Database (Denmark)

Mills, Daniel Brady; Canfield, Donald Eugene

2014-01-01

Recent studies challenge the classical view that the origin of animal life was primarily controlled by atmospheric oxygen levels. For example, some modern sponges, representing early-branching animals, can live under 200 times less oxygen than currently present in the atmosphere - levels commonly...... thought to have been maintained prior to their origination. Furthermore, it is increasingly argued that the earliest animals, which likely lived in low oxygen environments, played an active role in constructing the well-oxygenated conditions typical of the modern oceans. Therefore, while oxygen is still...

Kinetics of oxygen uncoupling of a copper based oxygen carrier

International Nuclear Information System (INIS)

Hu, Wenting; Donat, Felix; Scott, S.A.; Dennis, J.S.

2016-01-01

Highlights: • The kinetics of a Cu-based oxygen carrier was determined using a TGA. • A diffusion model was applied to remove mass transfer effects from rate parameters. • Thermodynamics are separated from kinetics, usually difficult for the CLOU reaction. • The rate parameters correctly described the behaviour in a fluidised bed. • The rate parameters can be used to predict performance of large CLOU systems. - Abstract: Here, an oxygen carrier consisting of 60 wt% CuO supported on a mixture of Al_2O_3 and CaO (23 wt% and 17 wt% respectively) was synthesised by wet-mixing powdered CuO, Al(OH)_3 and Ca(OH)_2, followed by calcination at 1000 °C. Its suitability for chemical looping with oxygen uncoupling (CLOU) was investigated. After 25 repeated redox cycles in either a thermogravimetric analyser (TGA) or a laboratory-scale fluidised bed, (with 5 vol% H_2 in N_2 as the fuel, and air as the oxidant) no significant change in either the oxygen uncoupling capacity or the overall oxygen availability of the carrier was found. In the TGA, it was found that the rate of oxygen release from the material was controlled by intrinsic chemical kinetics and external transfer of mass from the surface of the particles to the bulk gas. By modelling the various resistances, values of the rate constant for the decomposition were obtained. The activation energy of the reaction was found to be 59.7 kJ/mol (with a standard error of 5.6 kJ/mol) and the corresponding pre-exponential factor was 632 m"3/mol/s. The local rate of conversion within a particle was assumed to occur either (i) by homogeneous chemical reaction, or (ii) in uniform, non-porous grains, each reacting as a kinetically-controlled shrinking core. Upon cross validation against a batch fluidised bed experiment, the homogeneous reaction model was found to be more plausible. By accurately accounting for the various artefacts (e.g. mass transfer resistances) present in both TGA and fluidised bed experiments, it was

Heme biomolecule as redox mediator and oxygen shuttle for efficient charging of lithium-oxygen batteries

Science.gov (United States)

Ryu, Won-Hee; Gittleson, Forrest S.; Thomsen, Julianne M.; Li, Jinyang; Schwab, Mark J.; Brudvig, Gary W.; Taylor, André D.

2016-01-01

One of the greatest challenges with lithium-oxygen batteries involves identifying catalysts that facilitate the growth and evolution of cathode species on an oxygen electrode. Heterogeneous solid catalysts cannot adequately address the problematic overpotentials when the surfaces become passivated. However, there exists a class of biomolecules which have been designed by nature to guide complex solution-based oxygen chemistries. Here, we show that the heme molecule, a common porphyrin cofactor in blood, can function as a soluble redox catalyst and oxygen shuttle for efficient oxygen evolution in non-aqueous Li-O2 batteries. The heme's oxygen binding capability facilitates battery recharge by accepting and releasing dissociated oxygen species while benefiting charge transfer with the cathode. We reveal the chemical change of heme redox molecules where synergy exists with the electrolyte species. This study brings focus to the rational design of solution-based catalysts and suggests a sustainable cross-link between biomolecules and advanced energy storage. PMID:27759005

Guide du calcul avec les logiciels libres XCAS, Scilab, Bc, Gp, GnuPlot, Maxima, MuPAD

CERN Document Server

Connan, Guillaume

2008-01-01

Le Guide du Calcul avec les logiciels libres vous propose de maîtriser les bases de plusieurs logiciels gratuits de calcul formel et numérique, et de géométrie dynamique : XCAS, Scilab, Bc, Gp, GnuPlot, Maxima, Octave, Yacas, et également MuPAD (non libre). Ces logiciels sont multiplateformes (Windows, Mac, Linux) et s'installent rapidement. La grande originalité de cet ouvrage est de détailler pas à pas l'utilisation de plusieurs logiciels pour plusieurs types de calcul. Il propose ainsi des applications en mathématiques, en physique et en sciences de l'ingénieur (par exemple : équations différentielles utilisées en physique, traitement du son...). Il vous aidera à savoir utiliser le bon logiciel au bon moment pour résoudre le bon problème. Cet ouvrage s'adresse à toute personne voulant utiliser le calcul en mathématiques à l'aide de logiciels libres : étudiants en mathématiques ou en informatique, professeurs de lycée souhaitant utiliser ces outils dans le cadre de leur cours et jusqu'...

Nitric Oxide is Required for Homeostasis of Oxygen and Reactive Oxygen Species in Barley Roots under Aerobic Conditions

DEFF Research Database (Denmark)

Gupta, Kapuganti J; Hebelstrup, Kim; Kruger, Nicholas J

2014-01-01

Oxygen, the terminal electron acceptor for mitochondrial electron transport, is vital for plants because of its role in the production of ATP by oxidative phosphorylation. While photosynthetic oxygen production contributes to the oxygen supply in leaves, reducing the risk of oxygen limitation of ...... electron transport chain (Gupta et al., 2011). Thus, NO could influence oxygen consumption under normal aerobic conditions in roots, and it is this specific function that is assessed here.......Oxygen, the terminal electron acceptor for mitochondrial electron transport, is vital for plants because of its role in the production of ATP by oxidative phosphorylation. While photosynthetic oxygen production contributes to the oxygen supply in leaves, reducing the risk of oxygen limitation...

Quantitative Studies of the Reactions of Hot Tritium Atoms with Hydrocarbons and Hydrocarbon Mixtures; Etudes Quantitatives des Reactions des Atomes Chauds de Tritium avec les Hydrocarbures et les Melanges d'Hydrocarbures; Kolichestvennoe issledovanie reaktsij goryachikh atomov tritiya s gidrouglerodami i smesyami gidrouglerodov; Estudio Cuantitativo de las Reacciones de Atomos de Tritio Calientes con Hidrocarburos y Mezclas de Hidrocarburos

Energy Technology Data Exchange (ETDEWEB)

Urch, D. S.; Welch, M. J. [Department Of Chemistry, Queen Mary College. University of London, London (United Kingdom)

1965-04-15

The kinetic theory of hot-atom reactions is expanded to cover the general system of two reactive species and an inert moderator. From results with a single reactant and moderator, two reactants without moderator, and two reactants with moderator, values of, or ratios of, the reactivity integral I and the average logarithmic energy loss per collision a can be calculated. New results are presented from the reaction of hot tritium produced by the He{sup 3}(n, p)H{sup 3} reaction with the following systems (all contain oxygen scavenger): ethane with helium moderator butane with helium moderator neopentane with helium moderator ethane and butane with and without helium moderator ethane and neopentane with and without helium moderator Values of a and I for the three reactants are calculated from the three types of system and the agreement between the results is discussed in the terms of the accuracy of the model. The results obtained from the different systems agree to within the limits of the experimental error, and this shows that the kinetic theory model can be applied to hot-atom systems with some certainty and that the assumptions made when considering mixtures are reasonable ones. The ratios of the reactivity of the hydrocarbons in mixtures with regard to substitution reactions are not the same as the ratios of the number of hydrogen atoms in the hydrocarbons. The values obtained for these ratios are explained in terms of the values of I and S (the collision cross-section) for the hydrocarbons. (author) [French] Les auteurs etendent la theorie cinetique des reactions des atomes chauds au systeme general forme par deux especes reactives et un ralentisseur inerte. A partir des resultats obtenus au moyen d'un seul corps en reaction et d'un ralentisseur, de deux corps en reaction sans ralentisseur et de deux corps en reaction avec ralentisseur, il est possible de calculer les valeurs ou les rapports de l'integrale de reactivite I, et de la perte d'energie logarithmique

High Selectivity Oxygen Delignification

Energy Technology Data Exchange (ETDEWEB)

Lucian A. Lucia

2005-11-15

Project Objective: The objectives of this project are as follows: (1) Examine the physical and chemical characteristics of a partner mill pre- and post-oxygen delignified pulp and compare them to lab generated oxygen delignified pulps; (2) Apply the chemical selectivity enhancement system to the partner pre-oxygen delignified pulps under mill conditions (with and without any predetermined amounts of carryover) to determine how efficiently viscosity is preserved, how well selectivity is enhanced, if strength is improved, measure any yield differences and/or bleachability differences; and (3) Initiate a mill scale oxygen delignification run using the selectivity enhancement agent, collect the mill data, analyze it, and propose any future plans for implementation.

Investigation of the singlet delta oxygen and ozone yields from the pulsed radiolysis of oxygen and oxygen-noble gas mixtures

International Nuclear Information System (INIS)

Zediker, M.S.

1984-01-01

The experiments discussed herein were performed with a flowing gas apparatus coupled to the University of Illinois TRIGA reactor. The detectors (lambda = 1.27 μ 634 nm) were calibrated with a novel NO 2 titration scheme and the absorbed dose was estimated from the ozone concentrations measured in pure oxygen. The results of these experiments revealed an O 2 (a 1 Δ) production efficiency of 0.14% for direct nuclear pumping in an argon-oxygen mixture. Extensive modeling of the oxygen and argon-oxygen mixtures were benchmarked against these and other experiments. However, good agreement over a broad absorbed dose range was only possible if the O 4 + + O 4 - neutralization reaction was assumed to be nondissociative. In a second set of experiments with a nuclear sustained electrical discharge (low E/N), the O 2 (a 1 Δ) production efficiency was approx.0.40% for the electrical power densities examined. In addition, the O 2 (a 1 Δ) was observed to scale with the square root of the electrical power deposition but was independent of the oxygen concentration. A simple analytic model was developed which explains this behavior as a characteristic of an externally sustained discharge involving an electron attaching gas such as oxygen. The results of these experiments and the modeling of the chemical kinetics are discussed with an emphasis on optimizing the O 2 (a 1 Δ) and O 3 yields

Improved arterial blood oxygenation following intravenous infusion of cold supersaturated dissolved oxygen solution.

Science.gov (United States)

Grady, Daniel J; Gentile, Michael A; Riggs, John H; Cheifetz, Ira M

2014-01-01

One of the primary goals of critical care medicine is to support adequate gas exchange without iatrogenic sequelae. An emerging method of delivering supplemental oxygen is intravenously rather than via the traditional inhalation route. The objective of this study was to evaluate the gas-exchange effects of infusing cold intravenous (IV) fluids containing very high partial pressures of dissolved oxygen (>760 mm Hg) in a porcine model. Juvenile swines were anesthetized and mechanically ventilated. Each animal received an infusion of cold (13 °C) Ringer's lactate solution (30 mL/kg/hour), which had been supersaturated with dissolved oxygen gas (39.7 mg/L dissolved oxygen, 992 mm Hg, 30.5 mL/L). Arterial blood gases and physiologic measurements were repeated at 15-minute intervals during a 60-minute IV infusion of the supersaturated dissolved oxygen solution. Each animal served as its own control. Five swines (12.9 ± 0.9 kg) were studied. Following the 60-minute infusion, there were significant increases in PaO2 and SaO2 (P < 0.05) and a significant decrease in PaCO2 (P < 0.05), with a corresponding normalization in arterial blood pH. Additionally, there was a significant decrease in core body temperature (P < 0.05) when compared to the baseline preinfusion state. A cold, supersaturated dissolved oxygen solution may be intravenously administered to improve arterial blood oxygenation and ventilation parameters and induce a mild therapeutic hypothermia in a porcine model.

In vivo integrated photoacoustic and confocal microscopy of hemoglobin oxygen saturation and oxygen partial pressure.

Science.gov (United States)

Wang, Yu; Hu, Song; Maslov, Konstantin; Zhang, Yu; Xia, Younan; Wang, Lihong V

2011-04-01

We developed dual-modality microscope integrating photoacoustic microscopy (PAM) and fluorescence confocal microscopy (FCM) to noninvasively image hemoglobin oxygen saturation (sO₂) and oxygen partial pressure (pO₂) in vivo in single blood vessels with high spatial resolution. While PAM measures sO₂ by imaging hemoglobin optical absorption at two wavelengths, FCM quantifies pO₂ using phosphorescence quenching. The variations of sO₂ and pO₂ values in multiple orders of vessel branches under hyperoxic (100% oxygen) and normoxic (21% oxygen) conditions correlate well with the oxygen-hemoglobin dissociation curve. In addition, the total concentration of hemoglobin is imaged by PAM at an isosbestic wavelength.

Microsensor and transcriptomic signatures of oxygen depletion in biofilms associated with chronic wounds: Biofilms and oxygen

Energy Technology Data Exchange (ETDEWEB)

James, Garth A. [Center for Biofilm Engineering, Montana State University, Bozeman Montana; Ge Zhao, Alice [Division of Dermatology, Department of Medicine, University of Washington, Seattle Washington; Usui, Marcia [Division of Dermatology, Department of Medicine, University of Washington, Seattle Washington; Underwood, Robert A. [Division of Dermatology, Department of Medicine, University of Washington, Seattle Washington; Nguyen, Hung [The Gene and Linda Voiland School of Chemical Engineering and Bioengineering, Washington State University, Pullman Washington; Beyenal, Haluk [The Gene and Linda Voiland School of Chemical Engineering and Bioengineering, Washington State University, Pullman Washington; deLancey Pulcini, Elinor [Center for Biofilm Engineering, Montana State University, Bozeman Montana; Agostinho Hunt, Alessandra [Department of Microbiology and Molecular Genetics, 5180 Biomedical and Physical Sciences, Michigan State University, East Lansing Michigan; Bernstein, Hans C. [Pacific Northwest National Laboratory, Chemical and Biological Signature Science, Richland Washington; Fleckman, Philip [Division of Dermatology, Department of Medicine, University of Washington, Seattle Washington; Olerud, John [Division of Dermatology, Department of Medicine, University of Washington, Seattle Washington; Williamson, Kerry S. [Center for Biofilm Engineering, Montana State University, Bozeman Montana; Franklin, Michael J. [Center for Biofilm Engineering, Montana State University, Bozeman Montana; Stewart, Philip S. [Center for Biofilm Engineering, Montana State University, Bozeman Montana

2016-02-16

Polymicrobial biofilms have been implicated in delayed wound healing, although the mechanisms by which biofilms impair wound healing are poorly understood. Many species of bacteria produce exotoxins and exoenzymes that may inhibit healing. In addition, oxygen consumption by biofilms may impede wound healing. In this study, we used oxygen microsensors to measure oxygen transects through in vitro-cultured biofilms, biofilms formed in vivo in a diabetic (db/db) mouse model, and ex vivo human chronic wound specimens. The results show that oxygen levels within both euthanized and live mouse wounds had steep gradients that reached minima ranging from 19 to 61% oxygen partial pressure, compared to atmospheric oxygen levels. The oxygen gradients in the mouse wounds were similar to those observed for clinical isolates cultured in vitro and for human ex vivo scabs. No oxygen gradients were observed for heat-killed scabs, suggesting that active metabolism by the viable bacteria contributed to the reduced oxygen partial pressure of the wounds. To characterize the metabolic activities of the bacteria in the mouse wounds, we performed transcriptomics analyses of Pseudomonas aeruginosa biofilms associated with the db/db mice wounds using Affymetrix microarrays. The results demonstrated that the bacteria expressed genes for metabolic activities associated with cell growth. Interestingly, the transcriptome results indicated that the bacteria within the wounds also experienced oxygen-limitation stress. Among the bacterial genes that were expressed in vivo were genes associated with the Anr-mediated hypoxia-stress response. Other bacterial stress response genes highly expressed in vivo were genes associated with stationary-phase growth, osmotic stress, and RpoH-mediated heat shock stress. Overall, the results support the hypothesis that the metabolic activities of bacteria in biofilms act as oxygen sinks in chronic wounds and that the depletion of oxygen contributes to the

Effects of the Oxygenation level on Formation of Different Reactive Oxygen Species During Photodynamic Therapy

OpenAIRE

Price, Michael; Heilbrun, Lance; Kessel, David

2013-01-01

We examined the effect of the oxygenation level on efficacy of two photosensitizing agents, both of which target lysosomes for photodamage but via different photochemical pathways. Upon irradiation, the chlorin termed NPe6 forms singlet oxygen in high yield while the bacteriopheophorbide WST11 forms only oxygen radicals (in an aqueous environment). Photokilling efficacy by WST11 in cell culture was impaired when the atmospheric oxygen concentration was reduced from 20% to 1%, while photokilli...

Determining the Source of Water Vapor in a Cerium Oxide Electrochemical Oxygen Separator to Achieve Aviator Grade Oxygen

Science.gov (United States)

Graf, John; Taylor, Dale; Martinez, James

2014-01-01

More than a metric ton of water is transported to the International Space Station (ISS) each year to provide breathing oxygen for the astronauts. Water is a safe and compact form of stored oxygen. The water is electrolyzed on ISS and ambient pressure oxygen is delivered to the cabin. A much smaller amount of oxygen is used each year in spacesuits to conduct Extra Vehicular Activities (EVAs). Space suits need high pressure (>1000 psia) high purity oxygen (must meet Aviator Breathing Oxygen "ABO" specifications, >99.5% O2). The water / water electrolysis system cannot directly provide high pressure, high purity oxygen, so oxygen for EVAs is transported to ISS in high pressure gas tanks. The tanks are relatively large and heavy, and the majority of the system launch weight is for the tanks and not the oxygen. Extracting high purity oxygen from cabin air and mechanically compressing the oxygen might enable on-board production of EVA grade oxygen using the existing water / water electrolysis system. This capability might also benefit human spaceflight missions, where oxygen for EVAs could be stored in the form of water, and converted into high pressure oxygen on-demand. Cerium oxide solid electrolyte-based ion transport membranes have been shown to separate oxygen from air, and a supported monolithic wafer form of the CeO2 electrolyte membrane has been shown to deliver oxygen at pressures greater than 300 psia. These supported monolithic wafers can withstand high pressure differentials even though the membrane is very thin, because the ion transport membrane is supported on both sides (Fig 1). The monolithic supported wafers have six distinct layers, each with matched coefficients of thermal expansion. The wafers are assembled into a cell stack which allows easy air flow across the wafers, uniform current distribution, and uniform current density (Fig 2). The oxygen separation is reported to be "infinitely selective" to oxygen [1] with reported purity of 99.99% [2

Study of the Dissociative Processes in O{sub 2} Discharges. Development of an Atomic Oxygen Beam Source; Etude de la dissociation de O{sub 2} dans les decharges d'oxygene. Application a la realisation de sources d'atomes

Energy Technology Data Exchange (ETDEWEB)

Pagnon, Daniel

1992-09-24

reaction pour l'excitation dissociative ou pour l'excitation directe de l'atome ont ete calcules a partir de sections efficaces publiees et d'une fonction de distribution en energie des electrons calculee. Nous avons montre que l'excitation dissociative est negligeable devant l'excitation directe pour un taux de dissociation inferieur a 2,5%. Nous avons montre que le taux de dissociation maximum de 20% obtenu etait limite par l'augmentation de la recombinaison atome-atome liee a l'echauffement de la paroi. Grace a ces resultats, une source continue d'atomes d'oxygene a ensuite ete realisee, ses parametres de fonctionnement optimises et l'etude de son implantation sur un bati MBE effectuee. La distribution spatiale de la densite d'atomes a ete mesuree dans le jet effusif par fluorescence induite a deux photons (lif) et par ionisation resonnante a trois photons (rmpi). Ces mesures laser ont permis d'observer l'existence d'une emission stimulee et d'evaluer son coefficient. Un modele de l'effusion des atomes a ete elabore qui permet de predire le flux d'atomes atteignant l'echantillon a traiter. Cette source a deja ete utilisee avec succes en milieu industriel pour oxyder in-situ des films de cuivre, de supraconducteurs, ou de substrats destines a la microelectronique rapide. La methode employee pour ce travail, ainsi que les diagnostics mis au point peuvent etre utilises dans d'autres types de plasmas, ou pour l'etude de la dissociation d'autres gaz moleculaires, afin de realiser des sources d'atomes pour le traitement de materiaux sur de plus grandes surfaces. (auteur)

Spatially monitoring oxygen level in 3D microfabricated cell culture systems using optical oxygen sensing beads

OpenAIRE

Wang, Lin; Acosta, Miguel A.; Leach, Jennie B.; Carrier, Rebecca L.

2013-01-01

Capability of measuring and monitoring local oxygen concentration at the single cell level (tens of microns scale) is often desirable but difficult to achieve in cell culture. In this study, biocompatible oxygen sensing beads were prepared and tested for their potential for real-time monitoring and mapping of local oxygen concentration in 3D micro-patterned cell culture systems. Each oxygen sensing bead is composed of a silica core loaded with both an oxygen sensitive Ru(Ph2phen3)Cl2 dye and ...

Femoral venous oxygen saturation is no surrogate for central venous oxygen saturation

NARCIS (Netherlands)

van Beest, Paul A.; van der Schors, Alice; Liefers, Henriëtte; Coenen, Ludo G. J.; Braam, Richard L.; Habib, Najib; Braber, Annemarije; Scheeren, Thomas W. L.; Kuiper, Michaël A.; Spronk, Peter E.

2012-01-01

Objective: The purpose of our study was to determine if central venous oxygen saturation and femoral venous oxygen saturation can be used interchangeably during surgery and in critically ill patients. Design: Prospective observational controlled study. Setting: Nonacademic university-affiliated

Oxygen Deficit: The Bio-energetic Pathophysiology

Directory of Open Access Journals (Sweden)

ABHAY KUMAR PANDEY

2014-09-01

Full Text Available Scarcity of oxygen in humans arises via three modes. The environment may have low oxygen to breath. There can be disease in respiratory system causing hindrance to uptake of oxygen from environment and the circulatory system may be sluggish to supply to body parts that starve for oxygen. Thirdly the chemico-cellular components of blood which carry oxygen may be lowered or defective. In reference to body cells several limiting sites and mechanisms affect the amount of oxygen delivered to them, and these are under regulatory control of several functional and metabolic systems.

MR Imaging-derived Oxygen-Hemoglobin Dissociation Curves and Fetal-Placental Oxygen-Hemoglobin Affinities.

Science.gov (United States)

Avni, Reut; Golani, Ofra; Akselrod-Ballin, Ayelet; Cohen, Yonni; Biton, Inbal; Garbow, Joel R; Neeman, Michal

2016-07-01

Purpose To generate magnetic resonance (MR) imaging-derived, oxygen-hemoglobin dissociation curves and to map fetal-placental oxygen-hemoglobin affinity in pregnant mice noninvasively by combining blood oxygen level-dependent (BOLD) T2* and oxygen-weighted T1 contrast mechanisms under different respiration challenges. Materials and Methods All procedures were approved by the Weizmann Institutional Animal Care and Use Committee. Pregnant mice were analyzed with MR imaging at 9.4 T on embryonic days 14.5 (eight dams and 58 fetuses; imprinting control region ICR strain) and 17.5 (21 dams and 158 fetuses) under respiration challenges ranging from hyperoxia to hypoxia (10 levels of oxygenation, 100%-10%; total imaging time, 100 minutes). A shorter protocol with normoxia to hyperoxia was also performed (five levels of oxygenation, 20%-100%; total imaging time, 60 minutes). Fast spin-echo anatomic images were obtained, followed by sequential acquisition of three-dimensional gradient-echo T2*- and T1-weighted images. Automated registration was applied to align regions of interest of the entire placenta, fetal liver, and maternal liver. Results were compared by using a two-tailed unpaired Student t test. R1 and R2* values were derived for each tissue. MR imaging-based oxygen-hemoglobin dissociation curves were constructed by nonlinear least square fitting of 1 minus the change in R2*divided by R2*at baseline as a function of R1 to a sigmoid-shaped curve. The apparent P50 (oxygen tension at which hemoglobin is 50% saturated) value was derived from the curves, calculated as the R1 scaled value (x) at which the change in R2* divided by R2*at baseline scaled (y) equals 0.5. Results The apparent P50 values were significantly lower in fetal liver than in maternal liver for both gestation stages (day 14.5: 21% ± 5 [P = .04] and day 17.5: 41% ± 7 [P hemoglobin dissociation curves with a shorter protocol that excluded the hypoxic periods was demonstrated. Conclusion MR imaging

Oxygen-reducing catalyst layer

Science.gov (United States)

O'Brien, Dennis P [Maplewood, MN; Schmoeckel, Alison K [Stillwater, MN; Vernstrom, George D [Cottage Grove, MN; Atanasoski, Radoslav [Edina, MN; Wood, Thomas E [Stillwater, MN; Yang, Ruizhi [Halifax, CA; Easton, E Bradley [Halifax, CA; Dahn, Jeffrey R [Hubley, CA; O'Neill, David G [Lake Elmo, MN

2011-03-22

An oxygen-reducing catalyst layer, and a method of making the oxygen-reducing catalyst layer, where the oxygen-reducing catalyst layer includes a catalytic material film disposed on a substrate with the use of physical vapor deposition and thermal treatment. The catalytic material film includes a transition metal that is substantially free of platinum. At least one of the physical vapor deposition and the thermal treatment is performed in a processing environment comprising a nitrogen-containing gas.

Extra-cerebral oxygenation influence on near-infrared-spectroscopy-determined frontal lobe oxygenation in healthy volunteers

DEFF Research Database (Denmark)

Sørensen, Henrik; Rasmussen, Peter; Siebenmann, Christoph

2015-01-01

INTRODUCTION: Frontal lobe oxygenation (Sc O2 ) is assessed by spatially resolved near-infrared spectroscopy (SR-NIRS) although it seems influenced by extra-cerebral oxygenation. We aimed to quantify the impact of extra-cerebral oxygenation on two SR-NIRS derived Sc O2 . METHODS: Multiple...... regression analysis estimated the influence of extra-cerebral oxygenation as exemplified by skin oxygenation (Sskin O2 ) on Sc O2 in 21 healthy subjects exposed to whole-body exercise in hypoxia (Fi O2 = 12%; n = 10) and normoxia (n = 12), whole-body heating, hyperventilation (n = 21), administration...... of norepinephrine with and without petCO2 -correction (n = 15), phenylephrine and head-up tilt (n = 7). Sc O2 was assessed simultaneously by NIRO-200NX (Sniro O2 ) and INVOS-4100 (Sinvos O2 ). Arterial (Sa O2 ) and jugular bulb oxygen saturations (Sj O2 ) were obtained. RESULTS: The regression analysis indicated...

Optimal oxygen saturation in premature infants

Directory of Open Access Journals (Sweden)

Meayoung Chang

2011-09-01

Full Text Available There is a delicate balance between too little and too much supplemental oxygen exposure in premature infants. Since underuse and overuse of supplemental oxygen can harm premature infants, oxygen saturation levels must be monitored and kept at less than 95% to prevent reactive oxygen species-related diseases, such as retinopathy of prematurity and bronchopulmonary dysplasia. At the same time, desaturation below 80 to 85% must be avoided to prevent adverse consequences, such as cerebral palsy. It is still unclear what range of oxygen saturation is appropriate for premature infants; however, until the results of further studies are available, a reasonable target for pulse oxygen saturation (SpO2 is 90 to 93% with an intermittent review of the correlation between SpO2 and the partial pressure of arterial oxygen tension (PaO2. Because optimal oxygenation depends on individuals at the bedside making ongoing adjustments, each unit must define an optimal target range and set alarm limits according to their own equipment or conditions. All staff must be aware of these values and adjust the concentration of supplemental oxygen frequently.

Femoral venous oxygen saturation is no surrogate for central venous oxygen saturation

NARCIS (Netherlands)

van Beest, Paul A.; van der Schors, Alice; Liefers, Henriette; Coenen, Ludo G. J.; Braam, Richard L.; Habib, Najib; Braber, Annemarije; Scheeren, Thomas W. L.; Kuiper, Michael A.; Spronk, Peter E.

2012-01-01

Objective:  The purpose of our study was to determine if central venous oxygen saturation and femoral venous oxygen saturation can be used interchangeably during surgery and in critically ill patients. Design:  Prospective observational controlled study. Setting:  Nonacademic university-affiliated

The oxygen effect and cellular adaptation

International Nuclear Information System (INIS)

Meshcherikova, V.V.; Vajnson, A.A.; Yarmonenko, S.P.

1979-01-01

The radiomodifying effect of oxygen was shown to depend on the level of cellular oxygenation prior to irradiation. Acute hypoxia created at the time of irradiation protects previously normally oxygenated cells with DMF approximately 1.4 times larger than that of cells cultured for 24 hours under conditions of mild hypoxia. It is suggested that a decrease in the radioprotective effect of acute hypoxia on chronically hypoxic cells is correlated with an appreciable decrease in the rate of oxygen consumption by these cells, due to which the oxygen concentration near the intracellular targets in chronically hypoxic cells may be higher than in normal cells under conditions of poor oxygenation

Interplay between O2 and SnO2: oxygen ionosorption and spectroscopic evidence for adsorbed oxygen.

Science.gov (United States)

Gurlo, Alexander

2006-10-13

Tin dioxide is the most commonly used material in commercial gas sensors based on semiconducting metal oxides. Despite intensive efforts, the mechanism responsible for gas-sensing effects on SnO(2) is not fully understood. The key step is the understanding of the electronic response of SnO(2) in the presence of background oxygen. For a long time, oxygen interaction with SnO(2) has been treated within the framework of the "ionosorption theory". The adsorbed oxygen species have been regarded as free oxygen ions electrostatically stabilized on the surface (with no local chemical bond formation). A contradiction, however, arises when connecting this scenario to spectroscopic findings. Despite trying for a long time, there has not been any convincing spectroscopic evidence for "ionosorbed" oxygen species. Neither superoxide ions O(2)(-), nor charged atomic oxygen O,(-) nor peroxide ions O(2)(2-) have been observed on SnO(2) under the real working conditions of sensors. Moreover, several findings show that the superoxide ion does not undergo transformations into charged atomic oxygen at the surface, and represents a dead-end form of low-temperature oxygen adsorption on reduced metal oxide.

Agir contre le harcèlement moral au travail pour en finir avec les idées reçues

CERN Document Server

Grebot, Elisabeth

2010-01-01

Censé être libérateur, le travail est souvent synonyme de mal-être. Le harcèlement, avec le stress et la surcharge, en est l'une des principales causes. Processus complexe qui implique de nombreux acteurs, le harcèlement touche plus de 12 % des salariés, majoritairement des femmes. Qu'il soit individuel, managérial ou stratégique, visant à contourner des procédures de licenciement, le harcèlement procède des mêmes modes opératoires : pression, humiliation, isolement, désolidarisation collective... qui conduisent la cible à vivre un véritable enfer. Au travers des principales idées reçues, Elisabeth Grebot détaille les mécanismes du harcèlement, les forces en présence, et montre le rôle essentiel du collectif pour mieux vivre ensemble au travail.

Incorporation of oxygen into abscisic acid and phaseic acid for molecular oxygen

International Nuclear Information System (INIS)

Creelman, R.A.; Zeevaart, J.A.D.

1984-01-01

Abscisic acid accumulates in detached, wilted leaves of Xanthium strumariu. When these leaves are subsequently rehydrated, phaseic acid, a catabolite of abscisic acid, accumulates. Analysis by gas chromatography-mass spectrometry of phaseic acid isolated from stressed and subsequently rehydrated leaves placed in an atmosphere containing 20% 18 O 2 and 80% N 2 indicates that one atom of 18 O is incorporated in the 6'-hydroxymethyl group of phaseic acid. This suggests that the enzyme that converts abscisic acid to phaseic acid is an oxygenase. Analysis by gas chromatography-mass spectrometry of abscisic acid isolated from stressed leaves kept in an atmosphere containing 18 O 2 indicates that one atom of 18 O is presented in the carboxyl group of abscisic acid. Thus, when abscisic acid accumulates in water-streesed leaves, only one of the four oxygens present in the abscisic acid molecule is derived from molecular oxygen. This suggest that either (a) the oxygen present in the 1'-, 4'-, and one of the two oxygens at the 1-position of abscisic acid arise from water, or (b) there exists a stored precursor with oxygen atoms already present in the 1'- and 4'-positions of abscisic acid which is converted to abscisic acid under conditions of water stress. 17 references, 2 figures, 1 tables

Incorporation of oxygen into abscisic Acid and phaseic Acid from molecular oxygen.

Science.gov (United States)

Creelman, R A; Zeevaart, J A

1984-05-01

Abscisic acid accumulates in detached, wilted leaves of Xanthium strumarium. When these leaves are subsequently rehydrated, phaseic acid, a catabolite of abscisic acid, accumulates. Analysis by gas chromatography-mass spectrometry of phaseic acid isolated from stressed and subsequently rehydrated leaves placed in an atmosphere containing 20% (18)O(2) and 80% N(2) indicates that one atom of (18)O is incorporated in the 6'-hydroxymethyl group of phaseic acid. This suggests that the enzyme that converts abscisic acid to phaseic acid is an oxygenase.Analysis by gas chromatography-mass spectrometry of abscisic acid isolated from stressed leaves kept in an atmosphere containing (18)O(2) indicates that one atom of (18)O is present in the carboxyl group of abscisic acid. Thus, when abscisic acid accumulates in water-stressed leaves, only one of the four oxygens present in the abscisic acid molecule is derived from molecular oxygen. This suggests that either (a) the oxygen present in the 1'-, 4'-, and one of the two oxygens at the 1-position of abscisic acid arise from water, or (b) there exists a stored precursor with oxygen atoms already present in the 1'- and 4'-positions of abscisic acid which is converted to abscisic acid under conditions of water stress.

Oxygen dependency of porfiromycin cytotoxicity

International Nuclear Information System (INIS)

Marshall, R.S.; Rauth, A.M.

1987-01-01

The authors determined the oxygen dependency of toxicity for the bioreductive alkylating agents mitomycin C (MMC) and porfiromycin (PM) to investigate whether the toxicities of these agents increase in the range of oxygen tensions over which cells become increasingly radioresistant. In the present work the oxygen dependency of PM in CHO cells was determined by assaying survival as a function of time of exposure to 1.0 μg/ml PM under various known levels of oxygen. While PM demonstrated preferential hypoxic cell toxicity, aerobic cell survival was reduced ten-fold after five hours of exposure. Conversely, PM toxicity after a five hour hypoxic exposure to <0.001% oxygen appeared to be greater than that observed for similar MMC exposures, suggesting that PM may be more selective than MMC in killing hypoxic rather than aerobic cells. The authors are currently investigating this preferential toxicity in two human cell lines, one of which is resistant to these agents. At present, these observations suggest that PM may be more effective than MMC at destroying tumour cells in regions of intermediate and low oxygen tensions which may survive radiotherapy, though the range of oxygen tensions which mediate toxicity is similar for both agents

Biogeochemistry: Oxygen burrowed away

NARCIS (Netherlands)

Meysman, F.J.R.

2014-01-01

Multicellular animals probably evolved at the seafloor after a rise in oceanic oxygen levels. Biogeochemical model simulations suggest that as these animals started to rework the seafloor, they triggered a negative feedback that reduced global oxygen.

Oxygen as a factor in eukaryote evolution - Some effects of low levels of oxygen on Saccharomyces cerevisiae

Science.gov (United States)

Jahnke, L.; Klein, H. P.

1979-01-01

A comparative study of the effects of varying levels of oxygen on some of the metabolic functions of the primitive eukaryote, Saccharomyces cerevisiae, has shown that these cells are responsive to very low levels of oxygen: the level of palmitoyl-Co A desaturase was greatly enhanced by only 0.03 vol % oxygen. Similarly, an acetyl-CoA synthetase associated predominantly with anaerobic growth was stimulated by as little as 0.1% oxygen, while an isoenzyme correlated with aerobic growth was maximally active at much higher oxygen levels (greater than 1%). Closely following this latter pattern were three mitochondrial enzymes that attained maximal activity only under atmospheric levels of oxygen.

Oxygen concentration inside a functioning photosynthetic cell.

Science.gov (United States)

Kihara, Shigeharu; Hartzler, Daniel A; Savikhin, Sergei

2014-05-06

The excess oxygen concentration in the photosynthetic membranes of functioning oxygenic photosynthetic cells was estimated using classical diffusion theory combined with experimental data on oxygen production rates of cyanobacterial cells. The excess oxygen concentration within the plesiomorphic cyanobacterium Gloeobactor violaceus is only 0.025 μM, or four orders of magnitude lower than the oxygen concentration in air-saturated water. Such a low concentration suggests that the first oxygenic photosynthetic bacteria in solitary form could have evolved ∼2.8 billion years ago without special mechanisms to protect them against reactive oxygen species. These mechanisms instead could have been developed during the following ∼500 million years while the oxygen level in the Earth's atmosphere was slowly rising. Excess oxygen concentrations within individual cells of the apomorphic cyanobacteria Synechocystis and Synechococcus are 0.064 and 0.25 μM, respectively. These numbers suggest that intramembrane and intracellular proteins in isolated oxygenic photosynthetic cells are not subjected to excessively high oxygen levels. The situation is different for closely packed colonies of photosynthetic cells. Calculations show that the excess concentration within colonies that are ∼40 μm or larger in diameter can be comparable to the oxygen concentration in air-saturated water, suggesting that species forming colonies require protection against reactive oxygen species even in the absence of oxygen in the surrounding atmosphere. Copyright © 2014 Biophysical Society. Published by Elsevier Inc. All rights reserved.

Oxygen Concentration Inside a Functioning Photosynthetic Cell

OpenAIRE

Kihara, Shigeharu; Hartzler, Daniel A.; Savikhin, Sergei

2014-01-01

The excess oxygen concentration in the photosynthetic membranes of functioning oxygenic photosynthetic cells was estimated using classical diffusion theory combined with experimental data on oxygen production rates of cyanobacterial cells. The excess oxygen concentration within the plesiomorphic cyanobacterium Gloeobactor violaceus is only 0.025 μM, or four orders of magnitude lower than the oxygen concentration in air-saturated water. Such a low concentration suggests that the first oxygenic...

Theory of oxygen isotope exchange

NARCIS (Netherlands)

den Otter, M.W.; Boukamp, Bernard A.; Bouwmeester, Henricus J.M.

2001-01-01

Transients for oxygen molecular mass numbers 32, 34 and 36 are derived which can be used for the interpretation of oxygen isotope exchange data based on measurement of concentrations of 16O2, 16O18O and 18O2 in the gas phase. Key parameters in the theory are the rate at which oxygen molecules are

Oxygen Effects in Anaerobic Digestion

Directory of Open Access Journals (Sweden)

Deshai Botheju

2009-10-01

Full Text Available Interaction of free oxygen in bio-gasification is a sparsely studied area, apart from the common argument of oxygen being toxic and inhibitory for anaerobic micro-cultures. Some studies have, however, revealed increased solubilisation of organic matter in the presence of some free oxygen in anaerobic digestion. This article analyses these counterbalancing phenomena with a mathematical modelling approach using the widely accepted biochemical model ADM 1. Aerobic oxidation of soluble carbon and inhibition of obligatory anaerobic organisms are modelled using standard saturation type kinetics. Biomass dependent first order hydrolysis kinetics is used to relate the increased hydrolysis rate with oxygen induced increase in biomass growth. The amended model, ADM 1-Ox (oxygen, has 25 state variables and 22 biochemical processes, presented in matrix form. The computer aided simulation tool AQUASIM 2.1 is used to simulate the developed model. Simulation predictions are evaluated against experimental data obtained using a laboratory batch test array comprising miniature anaerobic bio-reactors of 100 ml total volume each, operated under different initial air headspaces giving rise to the different oxygen loading conditions. The reactors were initially fed with a glucose solution and incubated at 35 Celsius, for 563 hours. Under the oxygen load conditions of 22, 44 and 88 mg/L, the ADM1-Ox model simulations predicted the experimental methane potentials quite adequately. Both the experimental data and the simulations suggest a linear reduction of methane potential with respect to the increase in oxygen load within this range.

Single Cell Oxygen Mapping (SCOM) by Scanning Electrochemical Microscopy Uncovers Heterogeneous Intracellular Oxygen Consumption

OpenAIRE

Santos, Carla Santana; Kowaltowski, Alicia J.; Bertotti, Mauro

2017-01-01

We developed a highly sensitive oxygen consumption scanning microscopy system using platinized platinum disc microelectrodes. The system is capable of reliably detecting single-cell respiration, responding to classical regulators of mitochondrial oxygen consumption activity as expected. Comparisons with commercial multi-cell oxygen detection systems show that the system has comparable errors (if not smaller), with the advantage of being able to monitor inter and intra-cell heterogeneity in ox...

Oxygen Isotopes in Chondritic Interplanetary Dust: Parent-Bodies and Nebular Oxygen Reservoirs

International Nuclear Information System (INIS)

Aleon, J; McKeegan, K D; Leshin, L

2006-01-01

Planetary objects have preserved various amounts of oxygen issued from isotopically different oxygen reservoirs reflecting their origin and physico-chemical history. An 16 O-rich component is preserved in refractory inclusions (CAIs) whereas meteorites matrices are enriched in an 16 O-poor component. The origin of these components is still unclear. The most recent models are based on isotope selective photodissociation of CO in a 16 O-rich nebula/presolr cloud resulting in a 16 O-poor gas in the outer part of the nebula. However because most meteorite components are thought to be formed in the inner 3AU of the solar nebula, the precise isotopic composition of outer solar system components is yet unknown. In that respect, the oxygen isotopic composition of cometary dust is a key to understand the origin of the solar system. The Stardust mission will bring back to the Earth dust samples from comet Wild2, a short period comet from the Jupiter family. A precise determination of the oxygen isotope composition of Wild2 dust grains is essential to decipher the oxygen reservoirs of the outer solar system. However, Stardust samples may be extremely fragmented upon impact in the collector. In addition, interplanetary dust particles (IDPs) collected in the stratosphere are likely to contain comet samples. Therefore, they started to investigate the oxygen isotopic composition of a suite of chondritic interplanetary dust particles that includes IDPs of potential cometary origin using a refined procedure to increase the lateral resolution for the analysis of Stardust grains or IDP subcomponents down to ∼ 3 (micro)m. High precision data for 4 IDPs were previously reported, here they have measured 6 additional IDPs

Grammaire progressive du français corrigés : niveau intermédiaire : avec 680 exercices

CERN Document Server

Thiévenaz, Odile

2013-01-01

Les corrigés de la 3e édition de la Grammaire progressive du français - niveau intermédiaire Ce qui fait le succès de cette grammaire : Une organisation claire : la leçon de grammaire sur la page de gauche ; les exercices d'entraînement sur la page de droite ; 52 chapitres présentant les points généralement abordés aux niveaux A2 et B1 du Cadre européen commun de référence pour les langues ; Un apprentissage progressif : il suit la progression naturelle des méthodes de français ; Un usage souple : pour la classe ou en auto-apprentissage ; Une préparation adaptée aux certifications : un entraînement efficace pour mieux réussir aux examens ; Une large place faite à l'évaluation : de nombreux exercices de révision et des bilans réguliers. À découvrir dans cette troisième édition tout en couleurs (ISBN 978 209 038 124 5) : Un CD audio avec 14 documents sonores ; 80 nouveaux exercices et activités communicatives ; Des chapitres révisés et des exercices plus variés ; Un test d'�...

L’ÉCOLE SOCIOLOGIQUE DE CRAIOVA: UNE ÉCOLE «JEUNE» AVEC UN ESPRIT «GUSTIEN»

Directory of Open Access Journals (Sweden)

Soufyane BADRAOUI

2015-04-01

Full Text Available La sociologie à Craiova étant une spécialité en matière d’offres de formation dans les trois cycles de l'enseignement supérieur: licence, master et doctorat, elle est aussi une pratique, ayant plus de 19 ans d'activité et d'expérience. Le nombre de projets de recherches doctorales et poste doctoraux réalisé et en cours de réalisation, justifie sa notoriété et de son appellation «L'école Sociologique de Craiova», notamment avec des partenaires pratiquant une sociologie d'action telle que l'Académie Roumaine et l'Institut Social Olténie. L'école sociologique de Craiova fait revivre la tradition sociologique roumaine et continue dans la lignée de la tradition de l'école Gustiènne. Il faut également noter que l'orientation des recherches sociologiques «Craiovienne» a pour objectif d'assurer un équilibre entre l'approche fondamentale et la recherche action. Dans ce qui suit, nous présenterons l’école sociologique de Craiova en mettant l’accent sur son fondateur, ses préoccupations, la recherche etc.

Robust high temperature oxygen sensor electrodes

DEFF Research Database (Denmark)

Lund, Anders

Platinum is the most widely used material in high temperature oxygen sensor electrodes. However, platinum is expensive and the platinum electrode may, under certain conditions, suffer from poisoning, which is detrimental for an oxygen sensor. The objective of this thesis is to evaluate electrode...... materials as candidates for robust oxygen sensor electrodes. The present work focuses on characterising the electrochemical properties of a few electrode materials to understand which oxygen electrode processes are limiting for the response time of the sensor electrode. Three types of porous platinum......-Dansensor. The electrochemical properties of the electrodes were characterised by electrochemical impedance spectroscopy (EIS), and the structures were characterised by x-ray diffraction and electron microscopy. At an oxygen partial pressures of 0.2 bar, the response time of the sensor electrode was determined by oxygen...

Preliminary Study of Oxygen-Enhanced Longitudinal Relaxation in MRI: A Potential Novel Biomarker of Oxygenation Changes in Solid Tumors

International Nuclear Information System (INIS)

O'Connor, James P.B.; Naish, Josephine H.; Parker, Geoff J.M.; Waterton, John C.; Watson, Yvonne; Jayson, Gordon C.; Buonaccorsi, Giovanni A.; Cheung, Sue; Buckley, David L.; McGrath, Deirdre M.; West, Catharine M.L.; Davidson, Susan E.; Roberts, Caleb; Mills, Samantha J.; Mitchell, Claire L.; Hope, Lynn; Ton, N. Chan; Jackson, Alan

2009-01-01

Purpose: There is considerable interest in developing non-invasive methods of mapping tumor hypoxia. Changes in tissue oxygen concentration produce proportional changes in the magnetic resonance imaging (MRI) longitudinal relaxation rate (R 1 ). This technique has been used previously to evaluate oxygen delivery to healthy tissues and is distinct from blood oxygenation level-dependent (BOLD) imaging. Here we report application of this method to detect alteration in tumor oxygenation status. Methods and materials: Ten patients with advanced cancer of the abdomen and pelvis underwent serial measurement of tumor R 1 while breathing medical air (21% oxygen) followed by 100% oxygen (oxygen-enhanced MRI). Gadolinium-based dynamic contrast-enhanced MRI was then performed to compare the spatial distribution of perfusion with that of oxygen-induced ΔR 1 . Results: ΔR 1 showed significant increases of 0.021 to 0.058 s -1 in eight patients with either locally recurrent tumor from cervical and hepatocellular carcinomas or metastases from ovarian and colorectal carcinomas. In general, there was congruency between perfusion and oxygen concentration. However, regional mismatch was observed in some tumor cores. Here, moderate gadolinium uptake (consistent with moderate perfusion) was associated with low area under the ΔR 1 curve (consistent with minimal increase in oxygen concentration). Conclusions: These results provide evidence that oxygen-enhanced longitudinal relaxation can monitor changes in tumor oxygen concentration. The technique shows promise in identifying hypoxic regions within tumors and may enable spatial mapping of change in tumor oxygen concentration.

Hyperbaric oxygen and radiotherapy

International Nuclear Information System (INIS)

Mayer, R.; Hamilton-Farrell, M.R.; Kleij, A.J. van der

2005-01-01

Background: Hyperbaric oxygen (HBO) therapy is the inhalation of 100% oxygen at a pressure of at least 1.5 atmospheres absolute (150 kPa). It uses oxygen as a drug by dissolving it in the plasma and delivering it to the tissues independent of hemoglobin. For a variety of organ systems, HBO is known to promote new vessel growth into areas with reduced oxygen tension due to poor vascularity, and therewith promotes wound healing and recovery of radiation-injured tissue. Furthermore, tumors may be sensitized to irradiation by raising intratumoral oxygen tensions. Methods: A network of hyperbaric facilities exists in Europe, and a number of clinical studies are ongoing. The intergovernmental framework COST B14 action 'Hyperbaric Oxygen Therapy' started in 1999. The main goal of the Working Group Oncology is preparation and actual implementation of prospective study protocols in the field of HBO and radiation oncology in Europe. Results: In this paper a short overview on HBO is given and the following randomized clinical studies are presented: (a) reirradiation of recurrent squamous cell carcinoma of the head and neck after HBO sensitization; (b) role of HBO in enhancing radiosensitivity on glioblastoma multiforme; (c) osseointegration in irradiated patients; adjunctive HBO to prevent implant failures; (d) the role of HBO in the treatment of late irradiation sequelae in the pelvic region. The two radiosensitization protocols (a, b) allow a time interval between HBO and subsequent irradiation of 10-20 min. Conclusion: Recruitment of centers and patients is being strongly encouraged, detailed information is given on www.oxynet.org. (orig.)

Oxygen potentials, oxygen diffusion coefficients and defect equilibria of nonstoichiometric (U,Pu)O{sub 2±x}

Energy Technology Data Exchange (ETDEWEB)

Kato, Masato, E-mail: kato.masato@jaea.go.jp [Fukushima Fuels and Materials Department, Japan Atomic Energy Agency, 4002 Narita-chou, O-arai machi, Ibaraki 311-1919 (Japan); Fast Reactor Fuel Cycle Technology Development Division, Japan Atomic Energy Agency, 4-33 Muramatsu Tokai-mura, Ibaraki 319-1194 (Japan); Watanabe, Masashi [Fukushima Fuels and Materials Department, Japan Atomic Energy Agency, 4002 Narita-chou, O-arai machi, Ibaraki 311-1919 (Japan); Fast Reactor Fuel Cycle Technology Development Division, Japan Atomic Energy Agency, 4-33 Muramatsu Tokai-mura, Ibaraki 319-1194 (Japan); Matsumoto, Taku; Hirooka, Shun; Akashi, Masatoshi [Fast Reactor Fuel Cycle Technology Development Division, Japan Atomic Energy Agency, 4-33 Muramatsu Tokai-mura, Ibaraki 319-1194 (Japan)

2017-04-15

Oxygen potential of (U,Pu)O{sub 2±x} was evaluated based on defect chemistry using an updated experimental data set. The relationship between oxygen partial pressure and deviation x in (U,Pu)O{sub 2±x} was analyzed, and equilibrium constants of defect formation were determined as functions of Pu content and temperature. Brouwer's diagrams were constructed using the determined equilibrium constants, and a relational equation to determine O/M ratio was derived as functions of O/M ratio, Pu content and temperature. In addition, relationship between oxygen potential and oxygen diffusion coefficients were described. - Highlights: •Brouwer’s diagrams for (U,Pu)O2 were constructed using the updated oxygen potential experimental data set. •Equilibrium constants of defect formation were determined as functions of Pu content and temperature. •Oxygen potential, oxygen diffusion coefficients, point defect concentration were described as functions of O/M ratio, Pu content and temperature.

Therapeutic effect of forearm low level light treatment on blood flow, oxygenation, and oxygen consumption

Science.gov (United States)

Wang, Pengbo; Sun, Jiajing; Meng, Lingkang; Li, Zebin; Li, Ting

2018-02-01

Low level light/laser therapy (LLLT) is considered as a novel, non-invasive, and potential therapy in a variety of psychological and physical conditions, due to its effective intricate photobiomodulation. The mechanism of LLLT is that when cells are stimulated by photons, mitochondria produce a large quantity of ATP, which accelerates biochemical responses in the cell. It is of great significance to gain a clear insight into the change or interplay of various physiological parameters. In this study, we used functional near-infrared spectroscopy (fNIRS) and venous-occlusion plethysmography to measure the LLLT-induced changes in blood flow, oxygenation, and oxygen consumption in human forearms in vivo. Six healthy human participants (4 males and 2 females) were administered with 810-nm light emitted by LED array in ten minutes and blood flow, oxygenation and oxygen consumption were detected in the entire experiment. We found that LLLT induced an increase of blood flow and oxygen consumption on the treated site. Meanwhile, LLLT took a good role in promoting oxygenation of regional tissue, which was indicated by a significant increase of oxygenated hemoglobin concentration (Δ[HbO2]), a nearly invariable deoxygenated hemoglobin concentration (Δ[Hb]) and a increase of differential hemoglobin concentration (Δ[HbD] = Δ[HbO2] - Δ[Hb]). These results not only demonstrate enormous potential of LLLT, but help to figure out mechanisms of photobiomodulation.

[Relationship among the Oxygen Concentration, Reactive Oxygen Species and the Biological Characteristics of Mouse Bone Marrow Hematopoietic Stem Cells].

Science.gov (United States)

Ren, Si-Hua; He, Yu-Xin; Ma, Yi-Ran; Jin, Jing-Chun; Kang, Dan

2016-02-01

To investigate the effects of oxygen concentration and reactive oxygen species (ROS) on the biological characteristics of hematopoietic stem cells (HSC) and to analyzed the relationship among the oxygen concentration, ROS and the biological characteristics of mouse HSC through simulation of oxygen environment experienced by PB HSC during transplantation. The detection of reactive oxygen species (ROS), in vitro amplification, directional differentiation (BFU-E, CFU-GM, CFU-Mix), homing of adhesion molecules (CXCR4, CD44, VLA4, VLA5, P-selectin), migration rate, CFU-S of NOD/SCID mice irradiated with sublethal dose were performed to study the effect of oxgen concentration and reactive oxygen species on the biological characteristics of mouse BM-HSC and the relationship among them. The oxygen concentrations lower than normal oxygen concentration (especially hypoxic oxygen environment) could reduce ROS level and amplify more Lin(-) c-kit(+) Sca-1(+) BM HSC, which was more helpful to the growth of various colonies (BFU-E, CFU-GM, CFU-Mix) and to maintain the migratory ability of HSC, thus promoting CFU-S growth significantly after the transplantation of HSC in NOD/SCID mice irradiated by a sublethal dose. BM HSC exposed to oxygen environments of normal, inconstant oxygen level and strenuously thanging of oxygen concentration could result in higher level of ROS, at the same time, the above-mentioned features and functional indicators were relatively lower. The ROS levels of BM HSC in PB HSCT are closely related to the concentrations and stability of oxygen surrounding the cells. High oxygen concentration results in an high level of ROS, which is not helpful to maintain the biological characteristics of BM HSC. Before transplantation and in vitro amplification, the application of antioxidancs and constant oxygen level environments may be beneficial for transplantation of BMMSC.

Workshop on Oxygen in the Terrestrial Planets

Science.gov (United States)

2004-01-01

This volume contains abstracts that have been accepted for presentation at the Workshop on Oxygen in the Terrestrial Planets, July 20-23,2004, Santa Fe, New Mexico. The contents include: 1) Experimental Constraints on Oxygen and Other Light Element Partitioning During Planetary Core Formation; 2) In Situ Determination of Fe(3+)/SigmaFe of Spinels by Electron Microprobe: An Evaluation of the Flank Method; 3) The Effect of Oxygen Fugacity on Large-Strain Deformation and Recrystallization of Olivine; 4) Plagioclase-Liquid Trace Element Oxygen Barometry and Oxygen Behaviour in Closed and Open System Magmatic Processes; 5) Core Formation in the Earth: Constraints from Ni and Co; 6) Oxygen Isotopic Compositions of the Terrestrial Planets; 7) The Effect of Oxygen Fugacity on Electrical Conduction of Olivine and Implications for Earth s Mantle; 8) Redox Chemical Diffusion in Silicate Melts: The Impact of the Semiconductor Condition; 9) Ultra-High Temperature Effects in Earth s Magma Ocean: Pt and W Partitioning; 10) Terrestrial Oxygen and Hydrogen Isotope Variations: Primordial Values, Systematics, Subsolidus Effects, Planetary Comparisons, and the Role of Water; 11) Redox State of the Moon s Interior; 12) How did the Terrestrial Planets Acquire Their Water?; 13) Molecular Oxygen Mixing Ratio and Its Seasonal Variability in the Martian Atmosphere; 14) Exchange Between the Atmosphere and the Regolith of Mars: Discussion of Oxygen and Sulfur Isotope Evidence; 15) Oxygen and Hydrogen Isotope Systematics of Atmospheric Water Vapor and Meteoric Waters: Evidence from North Texas; 16) Implications of Isotopic and Redox Heterogeneities in Silicate Reservoirs on Mars; 17) Oxygen Isotopic Variation of the Terrestrial Planets; 18) Redox Exchanges in Hydrous Magma; 19) Hydrothermal Systems on Terrestrial Planets: Lessons from Earth; 20) Oxygen in Martian Meteorites: A Review of Results from Mineral Equilibria Oxybarometers; 21) Non-Linear Fractionation of Oxygen Isotopes Implanted in

A Cabin Air Separator for EVA Oxygen

Science.gov (United States)

Graf, John C.

2011-01-01

Presently, the Extra-Vehicular Activities (EVAs) conducted from the Quest Joint Airlock on the International Space Station use high pressure, high purity oxygen that is delivered to the Space Station by the Space Shuttle. When the Space Shuttle retires, a new method of delivering high pressure, high purity oxygen to the High Pressure Gas Tanks (HPGTs) is needed. One method is to use a cabin air separator to sweep oxygen from the cabin air, generate a low pressure/high purity oxygen stream, and compress the oxygen with a multistage mechanical compressor. A main advantage to this type of system is that the existing low pressure oxygen supply infrastructure can be used as the source of cabin oxygen. ISS has two water electrolysis systems that deliver low pressure oxygen to the cabin, as well as chlorate candles and compressed gas tanks on cargo vehicles. Each of these systems can feed low pressure oxygen into the cabin, and any low pressure oxygen source can be used as an on-board source of oxygen. Three different oxygen separator systems were evaluated, and a two stage Pressure Swing Adsorption system was selected for reasons of technical maturity. Two different compressor designs were subjected to long term testing, and the compressor with better life performance and more favorable oxygen safety characteristics was selected. These technologies have been used as the basis of a design for a flight system located in Equipment Lock, and taken to Preliminary Design Review level of maturity. This paper describes the Cabin Air Separator for EVA Oxygen (CASEO) concept, describes the separator and compressor technology trades, highlights key technology risks, and describes the flight hardware concept as presented at Preliminary Design Review (PDR)

Oxygen Compatibility of Brass-Filled PTFE Compared to Commonly Used Fluorinated Polymers for Oxygen Systems

Science.gov (United States)

Herald, Stephen D.; Frisby, Paul M.; Davis, Samuel Eddie

2009-01-01

Safe and reliable seal materials for high-pressure oxygen systems sometimes appear to be extinct species when sought out by oxygen systems designers. Materials that seal well are easy to find, but these materials are typically incompatible with oxygen, especially in cryogenic liquid form. This incompatibility can result in seals that leak, or much worse, seals that easily ignite and burn during use. Materials that are compatible with oxygen are easy to find, such as the long list of compatible metals, but these metallic materials are limiting as seal materials. A material that seals well and is oxygen compatible has been the big game in the designer's safari. Scientists at the Materials Combustion Research Facility (MCRF), part of NASA/Marshall Space Flight Center (MSFC), are constantly searching for better materials and processes to improve the safety of oxygen systems. One focus of this effort is improving the characteristics of polymers used in the presence of an oxygen enriched environment. Very few systems can be built which contain no polymeric materials; therefore, materials which have good impact resistance, low heat of combustion, high auto-ignition temperature and that maintain good mechanical properties are essential. The scientists and engineers at the Materials Combustion Research Facility, in cooperation with seal suppliers, are currently testing a new formulation of polytetrafluoroethylene (PTFE) with Brass filler. This Brass-filled PTFE is showing great promise as a seal and seat material for high pressure oxygen systems. Early research has demonstrated very encouraging results, which could rank this material as one of the best fluorinated polymers ever tested. This paper will compare the data obtained for Brass-filled PTFE with other fluorinated polymers, such as TFE-Teflon (PTFE) , Kel-F 81, Viton A, Viton A-500, Fluorel , and Algoflon . A similar metal filled fluorinated polymer, Salox-M , was tested in comparison to Brass-filled PTFE to

Effects of normobaric versus hyperbaric oxygen on cell injury induced by oxygen and glucose deprivation in acute brain slices

Directory of Open Access Journals (Sweden)

Laurent Chazalviel

2016-01-01

Full Text Available Normobaric oxygen (NBO and hyperbaric oxygen (HBO are emerging as a possible co-treatment of acute ischemic stroke. Both have been shown to reduce infarct volume, to improve neurologic outcome, to promote endogenous tissue plasminogen activator-induced thrombolysis and cerebral blood flow, and to improve tissue oxygenation through oxygen diffusion in the ischemic areas, thereby questioning the interest of HBO compared to NBO. In the present study, in order to investigate and compare the oxygen diffusion effects of NBO and HBO on acute ischemic stroke independently of their effects at the vascular level, we used acute brain slices exposed to oxygen and glucose deprivation, an ex vivo model of brain ischemia that allows investigating the acute effects of NBO (partial pressure of oxygen (pO 2 = 1 atmospheres absolute (ATA = 0.1 MPa and HBO (pO 2 = 2.5 ATA = 0.25 MPa through tissue oxygenation on ischemia-induced cell injury as measured by the release of lactate dehydrogenase. We found that HBO, but not NBO, reduced oxygen and glucose deprivation-induced cell injury, indicating that passive tissue oxygenation (i.e. without vascular support of the brain parenchyma requires oxygen partial pressure higher than 1 ATA.

Oxygen - A Four Billion Year History

DEFF Research Database (Denmark)

Canfield, Donald Eugene

The air we breathe is twenty-one percent oxygen, an amount higher than on any other known world. While we may take our air for granted, Earth was not always an oxygenated planet. How did it become this way? Oxygen is the most current account of the history of atmospheric oxygen on Earth. Donald...... Canfield--one of the world's leading authorities on geochemistry, earth history, and the early oceans--covers this vast history, emphasizing its relationship to the evolution of life and the evolving chemistry of the Earth. With an accessible and colorful first-person narrative, he draws from a variety...... of fields, including geology, paleontology, geochemistry, biochemistry, animal physiology, and microbiology, to explain why our oxygenated Earth became the ideal place for life. Describing which processes, both biological and geological, act to control oxygen levels in the atmosphere, Canfield traces...

La réflexion des ondes électromagnétiques du milieu de gyrotropie anisotrope, avec un axe d'anisotropie et un angle d'incidence arbitraires

Science.gov (United States)

Tchalyk, A.

1994-01-01

The interaction of plane electromagnetic wave with half-infinit gyrotropic media for different directions of propagation of incident microwave radiation and various directions of gyrotropic axis are investigated. The equations for calculation of wave's parameters exited in media and reflected from media-surface are obtained. On étudie l'interaction d'une onde électromagnétique plane avec un milieu gyrotrope à demi-infini dans le cas d'une direction arbitraire de propagation de la radiation électromagnétique incidente et de l'axe de gyrotropie. On a obtenu des expressions permettant de calculer les caractéristiques des ondes excitées dans et par le milieu.

The influence of systemic hemodynamics and oxygen transport on cerebral oxygen saturation in neonates after the Norwood procedure.

Science.gov (United States)

Li, Jia; Zhang, Gencheng; Holtby, Helen; Guerguerian, Anne-Marie; Cai, Sally; Humpl, Tilman; Caldarone, Christopher A; Redington, Andrew N; Van Arsdell, Glen S

2008-01-01

Ischemic brain injury is an important morbidity in neonates after the Norwood procedure. Its relationship to systemic hemodynamic oxygen transport is poorly understood. Sixteen neonates undergoing the Norwood procedure were studied. Continuous cerebral oxygen saturation was measured by near-infrared spectroscopy. Continuous oxygen consumption was measured by respiratory mass spectrometry. Pulmonary and systemic blood flow, systemic vascular resistance, oxygen delivery, and oxygen extraction ratio were derived with measurements of arterial, and superior vena cava and pulmonary venous gases and pressures at 2- to 4-hour intervals during the first 72 hours in the intensive care unit. Mean cerebral oxygen saturation was 66% +/- 12% before the operation, reduced to 51% +/- 13% on arrival in the intensive care unit, and remained low during the first 8 hours; it increased to 56% +/- 9% at 72 hours, still significantly lower than the preoperative level (P blood flow and oxygen delivery (P blood flow (P = .001) and hemoglobin (P = .02) and negatively correlated with systemic vascular resistance (P = .003). It was not correlated with oxygen consumption (P > .05). Cerebral oxygen saturation decreased significantly in neonates during the early postoperative period after the Norwood procedure and was significantly influenced by systemic hemodynamic and metabolic events. As such, hemodynamic interventions to modify systemic oxygen transport may provide further opportunities to reduce the risk of cerebral ischemia and improve neurodevelopmental outcomes.

14 CFR 25.1441 - Oxygen equipment and supply.

Science.gov (United States)

2010-01-01

... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Oxygen equipment and supply. 25.1441... Oxygen equipment and supply. (a) If certification with supplemental oxygen equipment is requested, the... oxygen available in each source of supply. (d) The oxygen flow rate and the oxygen equipment for...

Impurities of oxygen in silicon

International Nuclear Information System (INIS)

Gomes, V.M.S.

1985-01-01

The electronic structure of oxygen complex defects in silicon, using molecular cluster model with saturation by watson sphere into the formalism of Xα multiple scattering method is studied. A systematic study of the simulation of perfect silicon crystal and an analysis of the increasing of atom number in the clusters are done to choose the suitable cluster for the calculations. The divacancy in three charge states (Si:V 2 + , Si:V 2 0 , Si:V 2 - ), of the oxygen pair (Si:O 2 ) and the oxygen-vacancy pair (Si:O.V) neighbours in the silicon lattice, is studied. Distortions for the symmetry were included in the Si:V 2 + and Si:O 2 systems. The behavior of defect levels related to the cluster size of Si:V 2 0 and Si:O 2 systems, the insulated oxygen impurity of silicon in interstitial position (Si:O i ), and the complexes involving four oxygen atoms are analysed. (M.C.K.) [pt

Incorporation of Oxygen into Abscisic Acid and Phaseic Acid from Molecular Oxygen 1

Science.gov (United States)

Creelman, Robert A.; Zeevaart, Jan A. D.

1984-01-01

Abscisic acid accumulates in detached, wilted leaves of Xanthium strumarium. When these leaves are subsequently rehydrated, phaseic acid, a catabolite of abscisic acid, accumulates. Analysis by gas chromatography-mass spectrometry of phaseic acid isolated from stressed and subsequently rehydrated leaves placed in an atmosphere containing 20% 18O2 and 80% N2 indicates that one atom of 18O is incorporated in the 6′-hydroxymethyl group of phaseic acid. This suggests that the enzyme that converts abscisic acid to phaseic acid is an oxygenase. Analysis by gas chromatography-mass spectrometry of abscisic acid isolated from stressed leaves kept in an atmosphere containing 18O2 indicates that one atom of 18O is present in the carboxyl group of abscisic acid. Thus, when abscisic acid accumulates in water-stressed leaves, only one of the four oxygens present in the abscisic acid molecule is derived from molecular oxygen. This suggests that either (a) the oxygen present in the 1′-, 4′-, and one of the two oxygens at the 1-position of abscisic acid arise from water, or (b) there exists a stored precursor with oxygen atoms already present in the 1′- and 4′-positions of abscisic acid which is converted to abscisic acid under conditions of water stress. PMID:16663564

Oxygen discharge and post-discharge kinetics experiments and modeling for the electric oxygen-iodine laser system.

Science.gov (United States)

Palla, A D; Zimmerman, J W; Woodard, B S; Carroll, D L; Verdeyen, J T; Lim, T C; Solomon, W C

2007-07-26

Laser oscillation at 1315 nm on the I(2P1/2)-->I(2P3/2) transition of atomic iodine has been obtained by a near resonant energy transfer from O2(a1Delta) produced using a low-pressure oxygen/helium/nitric oxide discharge. In the electric discharge oxygen-iodine laser (ElectricOIL) the discharge production of atomic oxygen, ozone, and other excited species adds levels of complexity to the singlet oxygen generator (SOG) kinetics which are not encountered in a classic purely chemical O2(a1Delta) generation system. The advanced model BLAZE-IV has been introduced to study the energy-transfer laser system dynamics and kinetics. Levels of singlet oxygen, oxygen atoms, and ozone are measured experimentally and compared with calculations. The new BLAZE-IV model is in reasonable agreement with O3, O atom, and gas temperature measurements but is under-predicting the increase in O2(a1Delta) concentration resulting from the presence of NO in the discharge and under-predicting the O2(b1Sigma) concentrations. A key conclusion is that the removal of oxygen atoms by NOX species leads to a significant increase in O2(a1Delta) concentrations downstream of the discharge in part via a recycling process; however, there are still some important processes related to the NOX discharge kinetics that are missing from the present modeling. Further, the removal of oxygen atoms dramatically inhibits the production of ozone in the downstream kinetics.

Actitudes de docentes de educación básica hacia las TIC (Attitudes of Teachers in Basic Education Towards ICT (Attitudes des enseignants d'éducation basique avec las TIC (Atitudes de docentes de educação básica frente às TIC

Directory of Open Access Journals (Sweden)

Joel Angulo-Armenta

2011-06-01

Full Text Available ResumenSe realizó un estudio relacional cuantitativo con el pro- pósito de describir las actitudes de los docentes hacia las TIC y su relación con variables sociodemográficas de los mismos (edad y género y con aquellas que indican posibilidades de acceso a las tecnologías (com- putadora en el hogar y Enciclomedia en el salón de clases. Los resultados señalan que de manera general los docentes poseen actitudes positivas hacia las TIC, especialmente en los docentes de género masculino y en aquellos que cuentan con mayores posibilidades de interacción con las mismas.AbstractA quantitative relational study was conducted in order to describe the attitudes of teachers towards ICT and their relation to certain socio-demo- graphic variables (age and gender and to variables that indicate accessibility of technology (computer at home and Enciclomedia —a bank of multimedia resources— in the classroom. The re- sults indicate the teachers generally have positive attitudes towards ICT, especially male teachers and those who have a greater chance of interac- tion with them.RésuméOn a réalisé une étude relationnelle quantitative avec l'objectif de décrire les attitudes des enseignants par ra- pport aux TIC et leurs rapport avec les variables sociodémographiques (âge et genre et avec celles qui indiquent possibilités d'accès aux technologies (ordinateur à la maison, et enciclome- dia dans la salle de cours. Les résultats signalent que d'une manière générale les enseignants ont des attitudes posi- tives par rapport aux TIC, notamment dans les enseignants de genre mascu- lin et dan ceux qui comptent avec plus de possibilités d'interagir avec les tech- nologies.ResumoRealizou-se um estudo relacional quantitativo com o objetivo de descre- ver as atitudes dos docentes frente às TIC, e a relação destas com as variá- veis sócio-demográficas dos primeiros (idade e gênero e com as variáveis que indicam possibilidades de acesso �

Analyzing the dependence of oxygen incorporation current density on overpotential and oxygen partial pressure in mixed conducting oxide electrodes.

Science.gov (United States)

Guan, Zixuan; Chen, Di; Chueh, William C

2017-08-30

The oxygen incorporation reaction, which involves the transformation of an oxygen gas molecule to two lattice oxygen ions in a mixed ionic and electronic conducting solid, is a ubiquitous and fundamental reaction in solid-state electrochemistry. To understand the reaction pathway and to identify the rate-determining step, near-equilibrium measurements have been employed to quantify the exchange coefficients as a function of oxygen partial pressure and temperature. However, because the exchange coefficient contains contributions from both forward and reverse reaction rate constants and depends on both oxygen partial pressure and oxygen fugacity in the solid, unique and definitive mechanistic assessment has been challenging. In this work, we derive a current density equation as a function of both oxygen partial pressure and overpotential, and consider both near and far from equilibrium limits. Rather than considering specific reaction pathways, we generalize the multi-step oxygen incorporation reaction into the rate-determining step, preceding and following quasi-equilibrium steps, and consider the number of oxygen ions and electrons involved in each. By evaluating the dependence of current density on oxygen partial pressure and overpotential separately, one obtains the reaction orders for oxygen gas molecules and for solid-state species in the electrode. We simulated the oxygen incorporation current density-overpotential curves for praseodymium-doped ceria for various candidate rate-determining steps. This work highlights a promising method for studying the exchange kinetics far away from equilibrium.

Influence of oxygen partial pressure on defect concentrations and on oxygen diffusion in UO2+x

International Nuclear Information System (INIS)

Pizzi, Elisabetta

2013-01-01

The hyper-stoichiometric uranium dioxide (UO 2+x ) is stable over a wide range of temperature and compositions. Such variations of composition and the eventual presence of doping elements or impurities lead to a variation of anionic and electronic defect concentrations. Moreover, many properties of this material are affected by its composition modifications, in particular their atomic transport properties. Firstly we developed a point defect model to evaluate the dependence of the electronic and oxygen defect concentrations upon temperature, equilibrium oxygen partial pressure and impurity content. The physical constants of the model, in particular the equilibrium constants of the defect formation reactions were determined from deviation from stoichiometry and electrical conductivity measurements of literature. This work enabled us to interpret our measures of conductivity, oxygen chemical and self- diffusion coefficients. From a quantitative standpoint, the analysis of our experimental results allows to evaluate the oxygen interstitial diffusion coefficient but also its formation energy. Moreover, an estimate of oxygen di-interstitial formation energy is also provided. Presence of oxygen clusters leads oxygen self- and chemical diffusion to decrease. X-ray Absorption Spectroscopy characterization shows the presence of the same defect in the entire deviation from stoichiometry studied, confirming the approach used to develop the model. (author) [fr

The vanadium/oxygen system in the analysis of sodium for oxygen

International Nuclear Information System (INIS)

Walker, J.A.J.; Price, W.B.

1981-05-01

An investigation of the V-O-Na system at 1023 K is described for oxygen in sodium contents of 5 to 25 ppm. Electron spectroscopy combined with depth profiling is used to determine the vanadium/oxygen ratios inwards from the surface of vanadium foil and these ratios are compared with theoretical predictions. The validity of the vanadium wire technique as an analytical method is examined and a model for the vanadium oxidation is suggested. (author)

Novel nanostructured oxygen sensor

Science.gov (United States)

Boardman, Alan James

New government regulations and industry requirements for medical oxygen sensors require the development of alternate materials and process optimization of primary sensor components. Current oxygen sensors are not compliant with the Restriction of Hazardous Substances (RoHS) Directive. This work focused on two areas. First, was finding suitable readily available materials for the sensor anodes. Second was optimizing the processing of the sensor cathode membrane for reduced delamination. Oxygen sensors were made using tin (Sn) and bismuth (Bi) electrodes, potassium hydroxide (KOH) and acetic acid (CH3COOH) electrolytes with platinum (Pt) and gold (Au) reference electrodes. Bi electrodes were fabricated by casting and pressing processes. Electrochemical characterization of the Sn and Bi electrodes was performed by Cyclic Voltammetry (CV), Electrochemical Impedance Spectroscopy (EIS) and sensing characterization per BSEN ISO 21647:2009 at various oxygen percentages, 0%, 20.9% and 100% oxygen levels with an automated test apparatus. The Sn anode with both electrolyte solutions showed good oxygen sensing properties and performance in a sensor. This system shows promise for replacement of Pb electrodes as required by the RoHS Directive. The Bi anode with Au cathode in both KOH and CH3COOH electrolytes showed acceptable performance and oxygen sensing properties. The Bi anodes fabricated by separate manufacturing methods demonstrated effectiveness for use in medical oxygen sensors. Gold thin films were prepared by magnetron sputtering on Flouroethylene Polymer (FEP) films. The FEP substrate temperature ranged from -77°C to 50°C. X-Ray Diffraction (XRD) and 4-point resistivity characterized the effects of substrate temperature to Au thin film particle size. XRD peak broadening and resistivity measurements showed a strong correlation of particle size to FEP substrate temperature. Particle size at 50°C was 594A and the -77°C particle size was 2.4 x 103A. Substrate

Oxygen, nitric oxide and articular cartilage

Directory of Open Access Journals (Sweden)

B Fermor

2007-04-01

Full Text Available Molecular oxygen is required for the production of nitric oxide (NO, a pro-inflammatory mediator that is associated with osteoarthritis and rheumatoid arthritis. To date there has been little consideration of the role of oxygen tension in the regulation of nitric oxide production associated with arthritis. Oxygen tension may be particularly relevant to articular cartilage since it is avascular and therefore exists at a reduced oxygen tension. The superficial zone exists at approximately 6% O2, while the deep zone exists at less than 1% O2. Furthermore, oxygen tension can alter matrix synthesis, and the material properties of articular cartilage in vitro.The increase in nitric oxide associated with arthritis can be caused by pro-inflammatory cytokines and mechanical stress. Oxygen tension significantly alters endogenous NO production in articular cartilage, as well as the stimulation of NO in response to both mechanical loading and pro-inflammatory cytokines. Mechanical loading and pro-inflammatory cytokines also increase the production of prostaglandin E2 (PGE2. There is a complex interaction between NO and PGE2, and oxygen tension can alter this interaction. These findings suggest that the relatively low levels of oxygen within the joint may have significant influences on the metabolic activity, and inflammatory response of cartilage as compared to ambient levels. A better understanding of the role of oxygen in the production of inflammatory mediators in response to mechanical loading, or pro-inflammatory cytokines, may aid in the development of strategies for therapeutic intervention in arthritis.

Oxygen permeation modelling of perovskites

NARCIS (Netherlands)

van Hassel, Bart A.; van Hassel, B.A.; Kawada, Tatsuya; Sakai, Natsuko; Yokokawa, Harumi; Dokiya, Masayuki; Bouwmeester, Henricus J.M.

1993-01-01

A point defect model was used to describe the oxygen nonstoichiometry of the perovskites La0.75Sr0.25CrO3, La0.9Sr0.1FeO3, La0.9Sr0.1CoO3 and La0.8Sr0.2MnO3 as a function of the oxygen partial pressure. Form the oxygen vacancy concentration predicte by the point defect model, the ionic conductivity

Oxygen potentials of transuranium oxides

International Nuclear Information System (INIS)

Haruyoshi Otobe; Mituso Akabori; Arai Yasuo; Kazuo Minato

2008-01-01

The oxygen potentials of pyrochlore-type Pu 2 Zr 2 O 7+y , fluorite-type (Pu 0.5 Zr 0.5 )O 2-x and AmO 2-x have been measured by the electromotive force (EMF) method with a zirconia solid-electrolyte. The oxygen potentials of these oxides were reviewed. The phase relations, microstructure, equilibrium state of these oxides were discussed, referring to the isothermal curve of the oxygen potentials. (authors)

Aquaculture en zone sahélo-soudanienne: diagnostic des ...

African Journals Online (AJOL)

SARAH

42.74%). However ... additional animal protein to the producers. ...... vigilance. Le manque de local à proximité de l'étang pour la surveillance les nuits et surtout en période de saison de froid et/ou de pluie ne facilite pas la tâche.

Centrifugal spray generator of singlet oxygen for a chemical oxygen-iodine laser

Czech Academy of Sciences Publication Activity Database

Špalek, Otomar; Hrubý, Jan; Čenský, Miroslav; Jirásek, Vít; Kodymová, Jarmila

2010-01-01

Roč. 100, č. 4 (2010), s. 793-802 ISSN 0946-2171 Grant - others:European Office of Aerospace R&D(US) FA8655-09-1-3091 Institutional research plan: CEZ:AV0Z10100523; CEZ:AV0Z20760514 Keywords : centrifugal generator of singlet oxygen * chemical oxygen-iodine laser Subject RIV: BH - Optics, Masers, Lasers Impact factor: 2.239, year: 2010

Controlling Oxygen Mobility in Ruddlesden–Popper Oxides

Directory of Open Access Journals (Sweden)

Dongkyu Lee

2017-03-01

Full Text Available Discovering new energy materials is a key step toward satisfying the needs for next-generation energy conversion and storage devices. Among the various types of oxides, Ruddlesden–Popper (RP oxides (A2BO4 are promising candidates for electrochemical energy devices, such as solid oxide fuel cells, owing to their attractive physicochemical properties, including the anisotropic nature of oxygen migration and controllable stoichiometry from oxygen excess to oxygen deficiency. Thus, understanding and controlling the kinetics of oxygen transport are essential for designing optimized materials to use in electrochemical energy devices. In this review, we first discuss the basic mechanisms of oxygen migration in RP oxides depending on oxygen nonstoichiometry. We then focus on the effect of changes in the defect concentration, crystallographic orientation, and strain on the oxygen migration in RP oxides. We also briefly review their thermal and chemical stability. Finally, we conclude with a perspective on potential research directions for future investigation to facilitate controlling oxygen ion migration in RP oxides.

21 CFR 868.5440 - Portable oxygen generator.

Science.gov (United States)

2010-04-01

... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Portable oxygen generator. 868.5440 Section 868...) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Therapeutic Devices § 868.5440 Portable oxygen generator. (a) Identification. A portable oxygen generator is a device that is intended to release oxygen for respiratory...

Hydrogen/oxygen injection stopping method for nuclear power plant and emergent hydrogen/oxygen injection device

International Nuclear Information System (INIS)

Ishida, Ryoichi; Ota, Masamoto; Takagi, Jun-ichi; Hirose, Yuki

1998-01-01

The present invention provides a device for suppressing increase of electroconductivity of reactor water during operation of a BWR type reactor, upon occurrence of reactor scram of the plant or upon stopping of hydrogen/oxygen injection due to emergent stoppage of an injection device so as not to deteriorate the integrity of a gas waste processing system upon occurrence of scram. Namely, when injection of hydrogen/oxygen is stopped during plant operation, the injection amount of hydrogen is reduced gradually. Subsequently, injection of hydrogen is stopped. With such procedures, the increase of electroconductivity of reactor water can be suppressed upon stoppage of hydrogen injection. When injection of hydrogen/oxygen is stopped upon shut down of the plant, the amount of hydrogen injection is changed depending on the change of the feedwater flow rate, and then the plant is shut down while keeping hydrogen concentration of feedwater to a predetermined value. With such procedures, increase of the reactor water electroconductivity can be suppressed upon stoppage of hydrogen injection. Upon emergent stoppage of the hydrogen/oxygen injection device, an emergent hydrogen/oxygen injection device is actuated to continue the injection of hydrogen/oxygen. With such procedures, elevation of reactor water electroconductivity can be suppressed. (I.S.)

Improvement of the heat exchanges by application of an electric field in the boiling freon 12; Amelioration des echanges thermiques par application d'un champ electrique dans le freon 12 bouillant

Energy Technology Data Exchange (ETDEWEB)

Bonjour, Emmanuel; Verdier, Jacques; Weil, Louis [Commissariat a l' energie atomique et aux energies alternatives - CEA, Centre d' Etudes Nucleaires de Grenoble (France)

1960-07-01

lt was already known that the heat exchanges by simple convection are considerably improved by the application of an electric field, but no study about the effect of this field when there is ebullition has been issued until now. The authors indicate the result of their experimental investigations which present a very great interest for the increase of the efficiency of the refrigeration cycles. Reprint of a paper published in Revue generale du froid, Sep 1960 [French] On savait deja qu'il etait possible d'ameliorer sensiblement les echanges thermiques dus a la simple convection par l'application d'un champ electrique, mais jusqu'a present, il n'existait pas de resultats concernant l'effet de ce champ en presence d'ebullition. Les auteurs indiquent les resultats de leur investigation experimentale qui presente un tres grand interet pour l'accroissement de l'efficacite du cycle de refrigeration. Reproduction d'un article publie dans Revue generale du froid, Sep 1960.

Gradually Increased Oxygen Administration Improved Oxygenation and Mitigated Oxidative Stress after Resuscitation from Severe Hemorrhagic Shock.

Science.gov (United States)

Luo, Xin; Yin, Yujing; You, Guoxing; Chen, Gan; Wang, Ying; Zhao, Jingxiang; Wang, Bo; Zhao, Lian; Zhou, Hong

2015-11-01

The optimal oxygen administration strategy during resuscitation from hemorrhagic shock (HS) is still controversial. Improving oxygenation and mitigating oxidative stress simultaneously seem to be contradictory goals. To maximize oxygen delivery while minimizing oxidative damage, the authors proposed the notion of gradually increased oxygen administration (GIOA), which entails making the arterial blood hypoxemic early in resuscitation and subsequently gradually increasing to hyperoxic, and compared its effects with normoxic resuscitation, hyperoxic resuscitation, and hypoxemic resuscitation in severe HS. Rats were subjected to HS, and on resuscitation, the rats were randomly assigned to four groups (n = 8): the normoxic, the hyperoxic, the hypoxemic, and the GIOA groups. Rats were observed for an additional 1 h. Hemodynamics, acid-base status, oxygenation, and oxidative injury were observed and evaluated. Central venous oxygen saturation promptly recovered only in the hyperoxic and the GIOA groups, and the liver tissue partial pressure of oxygen was highest in the GIOA group after resuscitation. Oxidative stress in GIOA group was significantly reduced compared with the hyperoxic group as indicated by the reduced malondialdehyde content, increased catalase activity, and the lower histologic injury scores in the liver. In addition, the tumor necrosis factor-α and interleukin-6 expressions in the liver were markedly decreased in the GIOA group than in the hyperoxic and normoxic groups as shown by the immunohistochemical staining. GIOA improved systemic/tissue oxygenation and mitigated oxidative stress simultaneously after resuscitation from severe HS. GIOA may be a promising strategy to improve resuscitation from HS and deserves further investigation.

Oxygen requirements of the earliest animals

DEFF Research Database (Denmark)

Mills, Daniel Brady; Ward, Lewis M.; Jones, CarriAyne

2014-01-01

likely exhibited a physiology and morphology similar to that of a modern sponge, its oxygen demands may have been met well before the enhanced oxygenation of the Ediacaran Period. Therefore, the origin of animals may not have been triggered by a contemporaneous rise in the oxygen content...

Mechanism of singlet oxygen deactivation in an electric discharge oxygen – iodine laser

Energy Technology Data Exchange (ETDEWEB)

Azyazov, V N; Mikheyev, P A; Torbin, A P [Samara Branch of the P.N. Lebedev Physical Institute, Russian Academy of Sciences, Samara (Russian Federation); Pershin, A A [S.P. Korolev Samara State Aerospace University, Samara (Russian Federation); Heaven, M C [Emory University, Atlanta, GA, 30322 (United States)

2014-12-31

We have determined the influence of the reaction of molecular singlet oxygen with a vibrationally excited ozone molecule O{sub 2}(a {sup 1}Δ) + O{sub 3}(ν) → 2O{sub 2} + O on the removal rate of O{sub 2}(a {sup 1}Δ) in an electric-discharge-driven oxygen – iodine laser. This reaction has been shown to be a major channel of O{sub 2}(a {sup 1}Δ) loss at the output of an electric-discharge singlet oxygen generator. In addition, it can also contribute significantly to the loss of O{sub 2}(a {sup 1}Δ) in the discharge region of the generator. (lasers)

Oxygen status during haemodialysis. The Cord-Group

DEFF Research Database (Denmark)

Nielsen, A L; Jensen, H Æ; Hegbrant, J

1995-01-01

Hypoxia during haemodialysis, mainly acetate, has been reported several times. In our study we have monitored oxygen status during 258 bicarbonate haemodialyses. A significant drop below 80 mmHg in mean oxygen tension occurred. Mean oxygen saturation reflected this drop but did not reach levels...... below 90%. The mean oxygen concentration was on the whole critical low, though slightly increasing during each haemodialysis session due to ultrafiltration. It is concluded that both hypoxia and hypoxaemia do occur during bicarbonate haemodialysis. To a group of patients generally having limited cardiac...... reserves, a poor oxygen status is a potentially serious complication to haemodialysis. Monitoring oxygen status is thus advisable....

21 CFR 868.1730 - Oxygen uptake computer.

Science.gov (United States)

2010-04-01

... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Oxygen uptake computer. 868.1730 Section 868.1730...) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Diagnostic Devices § 868.1730 Oxygen uptake computer. (a) Identification. An oxygen uptake computer is a device intended to compute the amount of oxygen consumed by a...

Enhanced oxygen delivery induced by perfluorocarbon emulsions in capillary tube oxygenators.

Science.gov (United States)

Vaslef, S N; Goldstick, T K

1994-01-01

Previous studies showed that a new generation of perfluorocarbon (PFC) emulsions increased tissue PO2 in the cat retina to a degree that could not be explained by the small increase in arterial O2 content seen after the infusion of low doses of 1 g PFC/kg body weight. It seems that increased O2 delivery at the tissue level after PFC infusion is caused by a local effect in the microcirculation. The authors studies this effect in vitro at steady state in a closed loop circuit, consisting of one of two types of capillary tube oxygenators, deoxygenator(s), a reservoir bag filled with anticoagulated bovine blood or saline (control), and a roller pump, to see if the addition of PFC would have an effect on the PO2 difference (delta PO2) across the capillary tube membrane oxygenator at a blood flow rate of 3 l/min. Perfluorocarbon was added in three incremental doses, each giving about 0.7 vol% of PFC. The delta PO2 across the oxygenator was measured before and after each dose. The mean percent increases in delta PO2 in blood for two types of oxygenators were 19.2 +/- 8% (mean +/- SD, n = 6, P = 0.002) and 9.9 +/- 4% (n = 3, P = 0.05), respectively, whereas the mean percent change in delta PO2 in saline was -4.9 +/- 2% (n = 2, P = 0.2). Inlet PO2s to the oxygenator were only minimally increased. The authors conclude that O2 delivery was significantly enhanced after injection of PFC in blood in this capillary tube model. A near wall excess of PFC particles may account for the augmentation of O2 diffusion in this model.

L’Amleto d’Arrigo Boito : deux versions énigmatiques avec Ducis et Dumas en dialogue Arrigo Boito’s Amleto: Two Enigmatic Versions Reversing Ducis and Changing Dumas

Directory of Open Access Journals (Sweden)

Costantino Maeder

2011-12-01

Full Text Available Le XIXe siècle est caractérisé par la redécouverte de Shakespeare. Cet article présente un exemple complexe de la réception de Shakespeare en France et en Italie: Hamlet a été à plusieurs reprises traduit et adapté à la scène et à l’opéra. Les traductions étaient pourtant loin d’être fidèles, ce qui n’était par contre pas le cas en Allemagne, si l’on pense à la traduction toujours apprécié des frères Schlegel. Ducis, par exemple, présente une histoire tout à fait incompatible avec le chef-d’œuvre de Shakespeare. Aussi Dumas père, bien qu’aidé par un traducteur, ne suit pas du tout l’original. Pourtant, ces deux versions, de même que leurs autres traductions, conditionneront longtemps la réception de Shakespeare dans les pays de l’Europe latine. Arrigo Boito offrira une version tout à fait autonome de l’Amleto, une désécriture d’auteur qui dialogue avec la version de Ducis, de Dumas, mais aussi avec les vraies traductions de Paul Meurice et de François-Victor Hugo.The 19th century is characterized by the rediscovery of Shakespeare. In this article, we will trace one complex example of Shakespeare’s reception in France and in Italy. Hamlet had been translated and adapted for the stage and for the opera several times. However, from the very beginning of the 18th century, authors like Ducis simply rewrote from scratch totally unauthentic versions which (misguided most French and Italian reception of Shakespeare. In the 19th century, Dumas offered a new and far more interesting interpretation which would be even more seminal for Latin Europe. Arrigo Boito’s Amleto dialogues in a rather astonishing and surprisingly modern way with the Dumas version of Hamlet, taking into account the more recent translations by François-Victor Hugo and Paul Meurice. As a result, the tragedy of the Danish prince is completely rewritten and deconstructed. As is often the case, Boito prefers to be the dwarf that

Oxygen dynamics around buried lesser sandeels Ammodytes tobianus (Linnaeus 1785): mode of ventilation and oxygen requirements

DEFF Research Database (Denmark)

Behrens, Jane W; Stahl, Henrik J; Steffensen, John F

2007-01-01

The oxygen environment around buried sandeels (Ammodytes tobianus) was monitored by planar optodes. The oxygen penetration depth at the sediment interface was only a few mm. Thus fish, typically buried at 1-4 cm depth, were generally in anoxic sediment. However, they induced an advective transport...... down along the body, referred to as ;plume ventilation'. Yet, within approximately 30 min the oxic plume was replenished by oxygen-depleted water from the gills. The potential for cutaneous respiration by the buried fish was thus of no quantitative importance. Calculations derived by three independent...... methods (each with N=3) revealed that the oxygen uptake of sandeel buried for 6-7 h was 40-50% of previous estimates on resting respirometry of non-buried fish, indicating lower O(2) requirements during burial on a diurnal timescale. Buried fish exposed to decreasing oxygen tensions gradually approached...

Oxygen index tests of thermosetting resins

Science.gov (United States)

Gilwee, W. J., Jr.; Parker, J. A.; Kourtides, D. A.

1980-01-01

The flammability characteristics of nine thermosetting resins under evaluation for use in aircraft interiors are described. These resins were evaluated using the Oxygen Index (ASTM 2863) testing procedure. The test specimens consisted of both neat resin and glass reinforced resin. When testing glass-reinforced samples it was observed that Oxygen Index values varied inversely with resin content. Oxygen values were also obtained on specimens exposed to temperatures up to 300 C. All specimens experienced a decline in Oxygen Index when tested at an elevated temperature.

Retrievable micro-inserts containing oxygen sensors for monitoring tissue oxygenation using EPR oximetry

International Nuclear Information System (INIS)

Dinguizli, M; Beghein, N; Gallez, B

2008-01-01

Tissue oxygenation is a crucial parameter in various physiopathological situations and can influence the therapeutic response of tumours. EPR oximetry is a reliable method for assessing and monitoring oxygen levels in vivo over long periods of time. Among the different paramagnetic oxygen sensors available for EPR oximetry, lithium phthalocyanine (LiPc) is a serious candidate for in vivo applications because of its narrow linewidth and its high signal-to-noise ratio. To enhance the biocompatibility of the sensors, fluoropolymer Teflon AF2400 was used to make cylindrical micro-inserts containing LiPc crystals. This new micro-pellet design has several advantages for in vivo studies, including the possibility of being able to choose the implant size, a high sensor content, the facility of in vivo insertion and complete protection with preservation of the oxygen sensor's characteristics. The response to oxygen and the kinetics of this response were tested using in vivo EPR: no differences were observed between micro-inserts and uncoated LiPc crystals. Pellets implanted in vivo in muscles conserved their responsiveness over a long period of time (∼two months), which is much longer than the few days of stability observed using LiPc crystals without protection by the implant. Finally, evaluation of the biocompatibility of the implants revealed no inflammatory reaction around the implantation area

Study of thermocouples for control of high temperatures; Etude de thermocouples pour le reperage des hautes temperatures

Energy Technology Data Exchange (ETDEWEB)

Villamayor, M [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires; Faculte des Sciences de l' Universite de Lyon - 69 (France)

1967-07-01

Previous works have shown that the tungsten-rhenium alloys thermocouples were a good instrument for control of high temperatures. From its, the author has studied the W/W 26 per cent and W 5 per cent Re/W 26 per cent Re french manufactured thermocouples and intended for control of temperatures in nuclear reactors until 2300 deg. C. In 'out-pile' study he determines the general characteristics of these thermocouples: average calibration curves, thermal shocks influence, response times, and alloys allowing the cold source compensation. The evolution of these thermocouples under thermal neutron flux has been determined by 'in-pile' study. The observations have led the author to propose a new type of thermocouples settled of molybdenum-columbium alloys. (author) [French] Des travaux anterieurs ont montre que les thermocouples des alliages tungstene-rhenium etaient susceptibles de reperer avec precision des hautes temperatures. A partir de la, l'auteur a etudie las thermocouples W/W 26 pour cent Re et W 5 pour cent Re/W 26 pour cent Re de fabrication francaise et destines au controle des temperatures dans les reacteurs nucleaires, jusqu'a 2300 deg. C Dans l'etude 'hors-pile' il a determine les caracteristiques generales de ces thermocouples: courbes d'etalonnage moyen, influence des chocs thermiques, temps de reponse, et alliages assurant la compensation de soudure froide. L'etude 'en-pile' a permis de rendre compte de l'evolution de ces thermocouples sous flux neutroniques. Les phenomenes observes ont conduit l'auteur a proposer un nouveau type de thermocouples constitues d'alliages molybdene-niobium. (auteur)

Oxidation of ruthenium thin films using atomic oxygen

Energy Technology Data Exchange (ETDEWEB)

McCoy, A.P.; Bogan, J.; Brady, A.; Hughes, G.

2015-12-31

In this study, the use of atomic oxygen to oxidise ruthenium thin films is assessed. Atomic layer deposited (ALD) ruthenium thin films (~ 3 nm) were exposed to varying amounts of atomic oxygen and the results were compared to the impact of exposures to molecular oxygen. X-ray photoelectron spectroscopy studies reveal substantial oxidation of metallic ruthenium films to RuO{sub 2} at exposures as low as ~ 10{sup 2} L at 575 K when atomic oxygen was used. Higher exposures of molecular oxygen resulted in no metal oxidation highlighting the benefits of using atomic oxygen to form RuO{sub 2}. Additionally, the partial oxidation of these ruthenium films occurred at temperatures as low as 293 K (room temperature) in an atomic oxygen environment. - Highlights: • X-ray photoelectron spectroscopy study of the oxidation of Ru thin films • Oxidation of Ru thin films using atomic oxygen • Comparison between atomic oxygen and molecular oxygen treatments on Ru thin films • Fully oxidised RuO{sub 2} thin films formed with low exposures to atomic oxygen.

Differences in breast tissue oxygenation following radiotherapy

International Nuclear Information System (INIS)

Dornfeld, Ken; Gessert, Charles E.; Renier, Colleen M.; McNaney, David D.; Urias, Rodolfo E.; Knowles, Denise M.; Beauduy, Jean L.; Widell, Sherry L.; McDonald, Bonita L.

2011-01-01

Tissue perfusion and oxygenation changes following radiotherapy may result from and/or contribute to the toxicity of treatment. Breast tissue oxygenation levels were determined in the treated and non-treated breast 1 year after radiotherapy for breast conserving treatment. Transcutaneous oxygenation varied between subjects in both treated and non-treated breast. Subjects without diabetes mellitus (n = 16) had an average oxygenation level of 64.8 ± 19.9 mmHg in the irradiated breast and an average of 72.3 ± 18.1 mmHg (p = 0.018) at the corresponding location in the control breast. Patients with diabetes (n = 4) showed a different oxygenation pattern, with lower oxygenation levels in control tissue and no decrease in the irradiated breast. This study suggests oxygenation levels in normal tissues vary between patients and may respond differently after radiotherapy.

Modification of radiation sensitivity: the oxygen effect

International Nuclear Information System (INIS)

Quintiliani, M.

1979-01-01

Four fundamental aspects of the oxygen effect in radiobiology are reviewed, with emphasis on single cell systems: (1) Radiosensitivity in relation to oxygen concentration. In many biological systems, this relationship is remarkably well represented by the well-known Howard-Flanders/Alper formula. Often, however, the degree of uncertainty associated with the estimation of the value of K in the formula is fairly high. Recent data on V79-753B cells indicate a biphasic influence of oxygen concentration on radiosensitivity that cannot be described in terms of the Howard-Flanders/Alper model. (2) The oxygen effect in relation to survival level. The influence of very low oxygen concentrations on the shoulder of the survival curves of irradiated cells is still controversial. Also, the oxygen dependence of repair processes for sublethal and potentially lethal damage need to be better defined. (3) Time-scale of the oxygen effect. All the experimental data obtained with the use of fast techniques indicate that the time scale of the oxygen effect is consistent with that of free radical reactions. This appears to be compatible with the hypothesis that oxygen acts by fixation of a radiation-induced reversible damage. The existence of two types of damage with different rates of decay is suggested, both in bacterial and mammalian cells. (4) Molecular mechanisms of the oxygen effect. In spite of the very large literature on this subject, the identification of the detailed molecular mechanisms of the oxygen effect must still be considered goals for future research

Oxygen-Methane Thruster, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — Orion Propulsion, Inc. proposes to develop an Oxygen and Methane RCS Thruster to advance the technology of alternate fuels. A successful Oxygen/CH4 RCS Thruster will...

[Recent technical advances in portable oxygen delivery systems].

Science.gov (United States)

Machida, K; Kawabe, Y; Mori, M; Haga, T

1992-08-01

According to a Japanese national survey (June 30, 1990), the number of patients receiving home oxygen therapy (HOT) has been greater than 18,000 since March 1985, when HOT was first covered by health insurance. The oxygen concentrator, especially the molecular sieve type, is the most common method of delivery (more than 90%). In April 1988, the portable oxygen cylinder was acknowledged by health insurance, and the liquid oxygen supply system in April 1990. Three types of portable oxygen delivery systems are available; oxygen cyclinder, liquid oxygen system, and oxygen concentrator (membrane type), of which the oxygen cylinder is most commonly used. In our hospital, portable oxygen supply systems were used in 80% of 168 HOT cases in 1990, and the use of 400 L aluminum oxygen cylinders at a flow rate of 1-2 L/min has been most popular. There is an strong desire from patients for lighter portable oxygen supply system of longer duration. In 19 patients with chronic respiratory failure, we evaluated a newly designed demand oxygen delivery system (DODS), which weighs 2.4 kg including the DOD device (TER-20 Teijin), 1.1 L oxygen cylinder made of ultressor, nasal cannula, and carrier. Arterial blood gases at rest (room air) were PaO2 61.9 +/- 6.3 torr, PaCO2 63.8 +/- 9.4 torr and pH 7.40 +/- 0.04. A crossover trial was performed under three conditions; breathing room air with no weight, and pulse oxygen flow and continuous oxygen flow each carrying 2.4 kg of weight. Both 6 minute walking (E1) and walking on a slow speed treadmill (E2) were studied.(ABSTRACT TRUNCATED AT 250 WORDS)

Oxygen Extraction from Minerals

Science.gov (United States)

Muscatello, Tony

2017-01-01

Oxygen, whether used as part of rocket bipropellant or for astronaut life support, is a key consumable for space exploration and commercialization. In Situ Resource Utilization (ISRU) has been proposed many times as a method for making space exploration more cost effective and sustainable. On planetary and asteroid surfaces the presence of minerals in the regolith that contain oxygen is very common, making them a potential oxygen resource. The majority of research and development for oxygen extraction from minerals has been for lunar regolith although this work would generally be applicable to regolith at other locations in space. This presentation will briefly survey the major methods investigated for oxygen extraction from regolith with a focus on the current status of those methods and possible future development pathways. The major oxygen production methods are (1) extraction from lunar ilmenite (FeTiO3) with either hydrogen or carbon monoxide, (2) carbothermal reduction of iron oxides and silicates with methane, and (3) molten regolith electrolysis (MRE) of silicates. Methods (1) and (2) have also been investigated in a two-step process using CO reduction and carbon deposition followed by carbothermal reduction. All three processes have byproducts that could also be used as resources. Hydrogen or carbon monoxide reduction produce iron metal in small amounts that could potentially be used as construction material. Carbothermal reduction also makes iron metal along with silicon metal and a glass with possible applications. MRE produces iron, silicon, aluminum, titanium, and glass, with higher silicon yields than carbothermal reduction. On Mars and possibly on some moons and asteroids, water is present in the form of mineral hydrates, hydroxyl (-OH) groups on minerals, andor water adsorbed on mineral surfaces. Heating of the minerals can liberate the water which can be electrolyzed to provide a source of oxygen as well. The chemistry of these processes, some key

Mitochondrial Respiration and Oxygen Tension.

Science.gov (United States)

Shaw, Daniel S; Meitha, Karlia; Considine, Michael J; Foyer, Christine H

2017-01-01

Measurements of respiration and oxygen tension in plant organs allow a precise understanding of mitochondrial capacity and function within the context of cellular oxygen metabolism. Here we describe methods that can be routinely used for the isolation of intact mitochondria, and the determination of respiratory electron transport, together with techniques for in vivo determination of oxygen tension and measurement of respiration by both CO 2 production and O 2 consumption that enables calculation of the respiratory quotient [CO 2 ]/[O 2 ].

Oxygen diffusion in bilayer polymer films

DEFF Research Database (Denmark)

Poulsen, Lars; Zebger, Ingo; Tofte, Jannik Pentti

2004-01-01

Experiments to quantify oxygen diffusion have been performed on polymer samples in which a film of poly(ethylene-co-norbornene) was cast onto a film of polystyrene which, in turn, was cast onto an oxygen-impermeable substrate. In the technique employed, the time evolution of oxygen transport...... through the film of poly(ethylene-co-norbornene) and into the polystyrene film was monitored using the phosphorescence of singlet oxygen as a spectroscopic probe. To analyze the data, it was necessary to solve Fick's second law of diffusion for both polymer films. Tractable analytical and numerical...

Determination of oxygen nonstoichiometry and diffusivity in mixed conducting oxides by oxygen Coulometric titration. II. Oxygen nonstoichiometry and defect model for La0.8Sr0.2CoO3-d

NARCIS (Netherlands)

Lankhorst, M.H.R.; Lankhorst, M.H.R.; Bouwmeester, Henricus J.M.

1997-01-01

The oxygen nonstoichiometry of La0.8Sr0.2CoO3-delta has been determined as a function of oxygen partial pressure and temperature using a high-temperature coulometric titration cell. For each measured value of the oxygen chemical potential, the oxygen nonstoichiometry is found to be nearly

Oxygen Transport Membranes

Energy Technology Data Exchange (ETDEWEB)

S. Bandopadhyay

2008-08-30

The focus of this research was to develop new membrane materials by synthesizing different compounds and determining their defect structures, crystallographic structures and electrical properties. In addition to measuring electrical conductivity, oxygen vacancy concentration was also evaluated using thermogravimetry, Neutron diffraction and Moessbauer Spectroscopy. The reducing conditions (CO{sub 2}/CO/H{sub 2} gas mixtures with steam) as encountered in a reactor environment can be expected to have significant influence on the mechanical properties of the oxides membranes. Various La based materials with and without Ti were selected as candidate membrane materials for OTM. The maximum electrical conductivity of LSF in air as a function of temperature was achieved at < 600 C and depends on the concentration of Sr (acceptor dopant). Oxygen occupancy in LSF was estimated using Neutron diffractometry and Moessbauer Spectroscopy by measuring magnetic moment changes depending on the Fe{sup 3+} and Fe{sup 4+} ratio. After extensive studies of candidate materials, lanthanum ferrites (LSF and LSFT) were selected as the favored materials for the oxygen transport membrane (OTM). LSF is a very good material for an OTM because of its high electronic and oxygen ionic conductivity if long term stability and mechanical strength are improved. LSFT not only exhibits p-type behavior in the high oxygen activity regime, but also has n-type conduction in reducing atmospheres. Higher concentrations of oxygen vacancies in the low oxygen activity regime may improve the performance of LSFT as an OTM. The hole concentration is related to the difference in the acceptor and donor concentration by the relation p = [Sr'{sub La}]-[Ti{sm_bullet}{sub Fe}]. The chemical formulation predicts that the hole concentration is, p = 0.8-0.45 or 0.35. Experimental measurements indicated that p is about {approx} 0.35. The activation energy of conduction is 0.2 eV which implies that LSCF conducts via the

Factors Determining the Oxygen Permeability of Biological Membranes: Oxygen Transport Across Eye Lens Fiber-Cell Plasma Membranes.

Science.gov (United States)

Subczynski, Witold Karol; Widomska, Justyna; Mainali, Laxman

2017-01-01

Electron paramagnetic resonance (EPR) spin-label oximetry allows the oxygen permeability coefficient to be evaluated across homogeneous lipid bilayer membranes and, in some cases, across coexisting membrane domains without their physical separation. The most pronounced effect on oxygen permeability is observed for cholesterol, which additionally induces the formation of membrane domains. In intact biological membranes, integral proteins induce the formation of boundary and trapped lipid domains with a low oxygen permeability. The effective oxygen permeability coefficient across the intact biological membrane is affected not only by the oxygen permeability coefficients evaluated for each lipid domain but also by the surface area occupied by these domains in the membrane. All these factors observed in fiber cell plasma membranes of clear human eye lenses are reviewed here.

Steady-state oxygen-solubility in niobium

International Nuclear Information System (INIS)

Schulze, K.; Jehn, H.

1977-01-01

During annealing of niobium in oxygen in certain temperature and pressure ranges steady states are established between the absorption of molecular oxygen and the evaporation of volatile oxides. The oxygen concentration in the niobium-oxygen α-solid solution is a function of oxygen pressure and temperature and has been redetermined in the ranges 10 -5 - 10 -2 Pa O 2 and 2,070 - 2,470 K. It follows differing from former results the equation csub(o) = 9.1 x 10 -6 x sub(po2) x exp (502000/RT) with csub(o) in at.-ppm, sub(po2) in Pa, T in K, R = 8.31 J x mol -1 x K -1 . The existence of steady states is limited to a temperature range from 1870 to 2470 K and to oxygen concentrations below the solubility limit given by solidus and solvus lines in the T-c diagram. In the experiments high-purity niobium wires with a specific electrical ratio rho (273 K)/rho(4.2 K) > 5,000 have been gassed under isothermal-isobaric conditions until the steady state has been reached. The oxygen concentration has been determined analytically by vacuum fusion extraction with platinum-flux technique as well as by electrical residual resistivity measurements at 4.2 K. (orig.) [de

21 CFR 868.5580 - Oxygen mask.

Science.gov (United States)

2010-04-01

... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Oxygen mask. 868.5580 Section 868.5580 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) MEDICAL DEVICES ANESTHESIOLOGY DEVICES Therapeutic Devices § 868.5580 Oxygen mask. (a) Identification. An oxygen mask is a device...

Blood conservation with membrane oxygenators and dipyridamole.

Science.gov (United States)

Teoh, K H; Christakis, G T; Weisel, R D; Madonik, M M; Ivanov, J; Wong, P Y; Mee, A V; Levitt, D; Benak, A; Reilly, P

1987-07-01

Cardiopulmonary bypass induces platelet activation and dysfunction, which result in platelet deposition and depletion. Reduced platelet numbers and abnormal platelet function may contribute to postoperative bleeding. A membrane oxygenator may preserve platelets and reduce bleeding more than a bubble oxygenator, and the antiplatelet agent dipyridamole may protect platelets intraoperatively and reduce bleeding postoperatively. A prospective randomized trial was performed in 44 patients undergoing elective coronary artery bypass grafting to assess the effects of the membrane oxygenator and dipyridamole on platelet counts, platelet activation products, and postoperative bleeding. Patients who were randomized to receive a bubble oxygenator and no dipyridamole had the lowest postoperative platelet counts, the greatest blood loss, and the most blood products transfused. Platelet counts were highest and blood loss was least in patients randomized to receive a membrane oxygenator and dipyridamole (p less than .05). A bubble oxygenator with dipyridamole and a membrane oxygenator without dipyridamole resulted in intermediate postoperative platelet counts and blood loss. Arterial thromboxane B2 and platelet factor 4 concentrations were elevated on cardiopulmonary bypass in all groups. Both the membrane oxygenator and dipyridamole were independently effective (by multivariate analysis) in preserving platelets. Optimal blood conservation was achieved with a membrane oxygenator and dipyridamole.

The continuous inhalation of oxygen-15 for assessing regional oxygen extraction in the brain of man

International Nuclear Information System (INIS)

Jones, T.; Chesler, D.A.; Ter-Pogossian, M.M.

1976-01-01

A non-invasive steady-state method for studying the regional accumulation of oxygen in the brain by continuously inhaling oxygen-15 has been investigated. Oxygen respiration by tissue results in the formation of water of metabolism which may be considered as the 'exhaust product' of respiration. In turn the steady-state distribution of this product may be related to that of oxygen utilization. It has been found in monkeys than an appreciable component of the signal, recorded over the head during the inhalation of 15 O 2 , was attributable to the local production of 15 O-labelled water of metabolism. In man the distribution of radioactivity recorded over the head during 15 O 2 inhalation clearly related to active cerebal tissue. Theoretically the respiration product is linearly dependent on the oxygen extraction ratio of the tissue, and at normal cerebal perfusion it is less sensitive to changes in blood flow. At low rates of perfusion a more linear dependence on flow is shown. The dual dependence on blood flow and oxygen extraction limited the interpretation of the cerebal distribution obtained with this technique. Means for obtaining more definitive measurements with this approach are discussed. (author)

Using Tablet Computers with Elementary School Students with Special Needs: The Practices and Perceptions of Special Education Teachers and Teacher Assistants / Utilisation des tablettes électroniques avec des enfants d’école primaire à besoins spéciaux

Directory of Open Access Journals (Sweden)

Genevieve Marie Johnson

2013-12-01

Full Text Available Twelve special education teachers and teacher assistants who have instructional experience using iPads with children with special needs completed a survey that queried their practices and perceptions. In general, teachers and assistants were extremely positive about the value of iPads for children with special needs, particularly for children with autism, attention deficits and limitations of fine motor control. Special education teachers and teacher assistants reported most frequently using iPads to promote student language and literacy skills, although mathematics learning activities were also commonly reported. Enhanced student motivation was the most frequently reported benefit of using tablet computers in school followed by instructional planning advantages. Tablet computers appear to have the potential to be an essential aspect of individual program plans. Teaching tasks might reasonably include downloading and organizing specific applications on specific children’s tablets and professional development might increasingly focus of evaluation of tablet applications. Douze professeurs en éducation spéciale et aides-enseignants utilisant les iPads dans leur enseignement avec des enfants à besoins spéciaux ont rempli un questionnaire relatif à leurs pratiques et à leurs perceptions. En général, les enseignants et les aides-enseignants se sont révélés extrêmement positifs quant à la valeur des iPads pour les enfants à besoins spéciaux, en particulier pour les enfants avec autisme, avec un déficit d’attention et avec un contrôle limité de la motricité fine. Le plus souvent, les enseignants en éducation spéciale et les aides-enseignants ont indiqué avoir utilisé les iPads pour améliorer les compétences linguistiques et de littératie des élèves, bien que des activités d'apprentissage des mathématiques aient aussi été mentionnées fréquemment. Le renforcement de la motivation des élèves constituait l

Oxygenates to hike gasoline price

International Nuclear Information System (INIS)

Anon.

1992-01-01

This paper reports that cost of achieving required US gasoline formulations this winter in Environmental Protection Agency carbon monoxide (CO) nonattainment areas could reach 3-5 cents/gal, an Energy Information Administration analysis has found. EIA says new winter demand for gasoline blending oxygenates such as methyl tertiary butyl ether (MTBE) or ethanol created by 190 amendments to the Clean Air Act (CAA) will exceed US oxygenate production by 140,000-220,000 b/d. The shortfall must be made up from inventory or imports. EIA estimates the cost of providing incremental oxygenate to meet expected gasoline blending demand likely will result in a price premium of about 20 cents/gal of MTBE equivalent over traditional gasoline blend octane value. That cost likely will be added to the price of oxygenated gasoline

W.E. Henry Symposium Compendium, Lawrence Berkeley National Laboratory, September 19, 1997

Science.gov (United States)

1997-09-19

Society • Philosophical Society of Washington • Washington Academy of Sciences • New York Academy of Sciences • Institut International du Froid ...Powered Magnets" Reports of NRL Progress, Nov. 1958. 29. Henry, Warren E. "Aimantation dans les champs forts et approche a la saturation absolue du

1 Etude thermique expérimentale des suspensions non ...

African Journals Online (AJOL)

FAGLA

3Laboratoire de Caractérisation Thermophysique des Matériaux et .... [6] ont étudié le stockage et de distribution du froid par chaleur latente en traitant, ...... siège du meilleur échange thermique, d‟où le nombre de Nusselt le plus élevé).

Silibinin activates AMP-activated protein kinase to protect neuronal cells from oxygen and glucose deprivation-re-oxygenation.

Science.gov (United States)

Xie, Zhi; Ding, Sheng-quan; Shen, Ya-fang

2014-11-14

In this study, we explored the cytoprotective potential of silibinin against oxygen-glucose deprivation (OGD)-induced neuronal cell damages, and studied underling mechanisms. In vitro model of ischemic stroke was created by keeping neuronal cells (SH-SY5Y cells and primary mouse cortical neurons) in an OGD condition followed by re-oxygenation. Pre-treatment of silibinin significantly inhibited OGD/re-oxygenation-induced necrosis and apoptosis of neuronal cells. OGD/re-oxygenation-induced reactive oxygen species (ROS) production and mitochondrial membrane potential (MMP) reduction were also inhibited by silibinin. At the molecular level, silibinin treatment in SH-SY5Y cells and primary cortical neurons led to significant AMP-activated protein kinase (AMPK) signaling activation, detected by phosphorylations of AMPKα1, its upstream kinase liver kinase B1 (LKB1) and the downstream target acetyl-CoA Carboxylase (ACC). Pharmacological inhibition or genetic depletion of AMPK alleviated the neuroprotective ability of silibinin against OGD/re-oxygenation. Further, ROS scavenging ability by silibinin was abolished with AMPK inhibition or silencing. While A-769662, the AMPK activator, mimicked silibinin actions and suppressed ROS production and neuronal cell death following OGD/re-oxygenation. Together, these results show that silibinin-mediated neuroprotection requires activation of AMPK signaling. Copyright © 2014 Elsevier Inc. All rights reserved.

Pulsed electron-beam-sustained discharge in oxygen-containing gas mixtures: electrical characteristics, spectroscopy,and singlet oxygen yield

International Nuclear Information System (INIS)

Vagin, Nikolai P; Ionin, Andrei A; Klimachev, Yu M; Kotkov, A A; Podmar'kov, Yu P; Seleznev, L V; Sinitsyn, D V; Frolov, M P; Yuryshev, Nikolai N; Kochetov, Igor' V; Napartovich, A P; Hager, G D

2004-01-01

The electrical and spectroscopic characteristics of electron-beam-sustained discharge (EBSD) in oxygen and oxygen-containing gas mixtures are studied experimentally under gas pressures up to 100 Torr in a large excitation volume (∼18 L). It is shown that the EBSD in pure oxygen and its mixtures with inert gases is unstable and is characterised by a small specific energy contribution. The addition of small amounts (∼1%-10%) of carbon monoxide or hydrogen to oxygen or its mixtures with inert gases considerably improves the stability of the discharge, while the specific energy contribution W increases by more then an order of magnitude, achieving ∼6.5 kJ L -1 atm -1 per molecular component of the gas mixture. A part of the energy supplied to the EBSD is spent to excite vibrational levels of molecular additives. This was demonstrated experimentally by the initiation of a CO laser based on the O 2 : Ar : CO = 1 : 1 : 0.1 mixture. Experimental results on spectroscopy of the excited electronic states O 2 (a 1 Δ g ) and O 2 (b 1 Σ g + ), of oxygen formed in the EBSD are presented. A technique was worked out for measuring the concentration of singlet oxygen in the O 2 (a 1 Δ g ) state in the afterglow of the pulsed EBSD by comparing with the radiation intensity of singlet oxygen of a given concentration produced in a chemical generator. Preliminary measurements of the singlet-oxygen yield in the EBSD show that its value ∼3% for W ∼ 1.0 kJ L -1 atm -1 is in agreement with the theoretical estimate. Theoretical calculations performed for W ∼ 6.5 kJ L -1 atm -1 at a fixed temperature show that the singlet-oxygen yield may be ∼20%, which is higher than the value required to achieve the lasing threshold in an oxygen-iodine laser at room temperature. (laser applications and other topics in quantum electronics)

Renal transplantation induces mitochondrial uncoupling, increased kidney oxygen consumption, and decreased kidney oxygen tension

NARCIS (Netherlands)

Papazova, Diana A.; Friederich-Persson, Malou; Joles, Jaap A.; Verhaar, Marianne C.

2015-01-01

Hypoxia is an acknowledged pathway to renal injury and ischemia-reperfusion (I/R) and is known to reduce renal oxygen tension (PO2). We hypothesized that renal I/R increases oxidative damage and induces mitochondrial uncoupling, resulting in increased oxygen consumption and hence kidney

Alarm points for fixed oxygen monitors

International Nuclear Information System (INIS)

Miller, G.C.

1987-05-01

Oxygen concentration monitors were installed in a vault where numerous pipes carried inert cryogens and gases to the Mirror Fusion Test Facility (MFTF-B) experimental vessel at Lawrence Livermore National Laboratory (LLNL). The problems associated with oxygen-monitoring systems and the reasons why such monitors were installed were reviewed. As a result of this review, the MFTF-B monitors were set to sound an evacuation alarm when the oxygen concentration fell below 18%. We chose the 18% alarm criterion to minimize false alarms and to allow time for personnel to escape in an oxygen-deficient environment

Comparison of airline passenger oxygen systems.

Science.gov (United States)

Byrne, N J

1995-08-01

The principal sources of oxygen for inflight passenger use, scheduled and unscheduled, are examined. Present practices of assessment of the passenger's "fitness to fly" are described. Three partner airlines, British Airways, U.S. Air, and Qantas, catering for more than 8000 oxygen requests annually, are compared. Analysis of customer use suggests that medical oxygen requests are frequently not clinically justified. The growth in demand, for both scheduled and unscheduled use of an expensive resource, supports the need for a "recommended best practice" among carriers. Passengers with respiratory disorders who will most benefit from inflight oxygen are vulnerable either to hypoxia or asthma.

Surface acoustic wave oxygen pressure sensor

Science.gov (United States)

Oglesby, Donald M. (Inventor); Upchurch, Billy T. (Inventor); Leighty, Bradley D. (Inventor)

1994-01-01

A transducer for the measurement of absolute gas-state oxygen pressure from pressures of less than 100 Pa to atmospheric pressure (1.01 x 10(exp 5) Pa) is based on a standard surface acoustic wave (SAW) device. The piezoelectric material of the SAW device is coated with a compound which will selectively and reversibly bind oxygen. When oxygen is bound by the coating, the mass of the coating increases by an amount equal to the mass of the bound oxygen. Such an increase in the mass of the coating causes a corresponding decrease in the resonant frequency of the SAW device.

Determination of oxygen in liquid sodium

International Nuclear Information System (INIS)

Torre, M. de la; Lapena, J.; Galindo, F.; Couchoud, M.; Celis, B. de; Lopez-Araquistain, J.L.

1976-01-01

The behaviour is analysed of a device for 'in-line' sampling and vacuum distillation. With this procedure 95 results were obtained for the solubility of oxygen in liquid sodium at temperatures between 125 0 and 300 0 C. The correlation between the concentration of oxygen in a saturation state and the corresponding temperature is represented by: 1g C = 6,17 - 2398/T, where C expressed ppm of oxygen by weight and T is the saturation temperature in 0 K. Reference is also made to the first results obtained with the electrochemical oxygen meter and the system for taking and recording data. (author)

Solar Energy Systems for Lunar Oxygen Generation

Science.gov (United States)

Colozza, Anthony J.; Heller, Richard S.; Wong, Wayne A.; Hepp, Aloysius F.

2010-01-01

An evaluation of several solar concentrator-based systems for producing oxygen from lunar regolith was performed. The systems utilize a solar concentrator mirror to provide thermal energy for the oxygen production process. Thermal energy to power a Stirling heat engine and photovoltaics are compared for the production of electricity. The electricity produced is utilized to operate the equipment needed in the oxygen production process. The initial oxygen production method utilized in the analysis is hydrogen reduction of ilmenite. Utilizing this method of oxygen production a baseline system design was produced. This baseline system had an oxygen production rate of 0.6 kg/hr with a concentrator mirror size of 5 m. Variations were performed on the baseline design to show how changes in the system size and process (rate) affected the oxygen production rate. An evaluation of the power requirements for a carbothermal lunar regolith reduction reactor has also been conducted. The reactor had a total power requirement between 8,320 to 9,961 W when producing 1000 kg/year of oxygen. The solar concentrator used to provide the thermal power (over 82 percent of the total energy requirement) would have a diameter of less than 4 m.

ODH, oxygen deficiency hazard cryogenic analysis

International Nuclear Information System (INIS)

Augustynowicz, S.D.

1994-01-01

An oxygen deficiency exists when the concentration of oxygen, by volume, drops to a level at which atmosphere supplying respiratory protection must be provided. Since liquid cryogens can expand by factors of 700 (LN 2 ) to 850 (LH e ), the uncontrolled release into an enclosed space can easily cause an oxygen-deficient condition. An oxygen deficiency hazard (ODH) fatality rate per hour (OE) is defined as: OE = Σ N i P i F i , where N i = number of components, P i = probability of failure or operator error, and F i = fatality factor. ODHs range from open-quotes unclassifiedclose quotes (OE -9 1/h) to class 4, which is the most hazardous (OE>10 -1 1/h). For Superconducting Super Collider Laboratory (SSCL) buildings where cryogenic systems exist, failure rate, fatality factor, reduced oxygen ratio, and fresh air circulation are examined

Oxygen measurements in thin ribbon silicon

Energy Technology Data Exchange (ETDEWEB)

Hyland, S L; Ast, D G; Baghdadi, A

1987-03-01

The oxygen content of thin silicon ribbons grown by the dendritic web technique was measured using a modification of the ASTM method based on Fourier transform infrared spectroscopy. Web silicon was found to have a high oxygen content, ranging from 13 to 19 ppma, calculated from the absorption peak associated with interstitial oxygen and using the new ASTM conversion coefficient. The oxygen concentration changed by about 10% along the growth direction of the ribbon. In some samples, a shoulder was detected on the absorption peak. A similar shoulder in Czochralski grown material has been variously interpreted in the literature as due to a complex of silicon, oxygen, and vacancies, or to a phase of SiO/sub 2/ developed along dislocations in the material. In the case of web silicon, it is not clear which is the correct interpretation.

Osmotic phenomena in application for hyperbaric oxygen treatment.

Science.gov (United States)

Babchin, A; Levich, E; Melamed M D, Y; Sivashinsky, G

2011-03-01

Hyperbaric oxygen (HBO) treatment defines the medical procedure when the patient inhales pure oxygen at elevated pressure conditions. Many diseases and all injuries are associated with a lack of oxygen in tissues, known as hypoxia. HBO provides an effective method for fast oxygen delivery in medical practice. The exact mechanism of the oxygen transport under HBO conditions is not fully identified. The objective of this article is to extend the colloid and surface science basis for the oxygen transport in HBO conditions beyond the molecular diffusion transport mechanism. At a pressure in the hyperbaric chamber of two atmospheres, the partial pressure of oxygen in the blood plasma increases 10 times. The sharp increase of oxygen concentration in the blood plasma creates a considerable concentration gradient between the oxygen dissolved in the plasma and in the tissue. The concentration gradient of oxygen as a non-electrolyte solute causes an osmotic flow of blood plasma with dissolved oxygen. In other words, the molecular diffusion transport of oxygen is supplemented by the convective diffusion raised due to the osmotic flow, accelerating the oxygen delivery from blood to tissue. A non steady state equation for non-electrolyte osmosis is solved asymptotically. The solution clearly demonstrates two modes of osmotic flow: normal osmosis, directed from lower to higher solute concentrations, and anomalous osmosis, directed from higher to lower solute concentrations. The fast delivery of oxygen from blood to tissue is explained on the basis of the strong molecular interaction between the oxygen and the tissue, causing an influx of oxygen into the tissue by convective diffusion in the anomalous osmosis process. The transport of the second gas, nitrogen, dissolved in the blood plasma, is also taken into the consideration. As the patient does not inhale nitrogen during HBO treatment, but exhales it along with oxygen and carbon dioxide, the concentration of nitrogen in blood

Étude des interactions hadroniques à deux corps chargés, induites sur des protons par un faisceau de $\\pi^{-}, K^{-}$, et $\\overline{p}$ entre 3 et 12 GeV/c, avec un angle de diffusion dans le centre de masse voisin de 90$^{o}$

CERN Document Server

Billoir, Pierre

1983-01-01

Étude des interactions hadroniques à deux corps chargés, induites sur des protons par un faisceau de $\\pi^{-}, K^{-}$, et $\\overline{p}$ entre 3 et 12 GeV/c, avec un angle de diffusion dans le centre de masse voisin de 90$^{o}$

Oxygenation measurement by multi-wavelength oxygen-dependent phosphorescence and delayed fluorescence: catchment depth and application in intact heart

NARCIS (Netherlands)

Balestra, Gianmarco M.; Aalders, Maurice C. G.; Specht, Patricia A. C.; Ince, Can; Mik, Egbert G.

2015-01-01

Oxygen delivery and metabolism represent key factors for organ function in health and disease. We describe the optical key characteristics of a technique to comprehensively measure oxygen tension (PO(2)) in myocardium, using oxygen-dependent quenching of phosphorescence and delayed fluorescence of

Oxygen diffusion in cuprate superconductors

International Nuclear Information System (INIS)

Routbort, J.L.; Rothman, S.J.

1995-01-01

Superconducting properties of the cuprate superconductors depend on the oxygen content of the material; the diffusion of oxygen is thus an important process in the fabrication and application of these materials. This article reviews studies of the diffusion of oxygen in La 2-x Sr x CuO 4 , YBa 2 Cu 3 O 7- δ, YBa 2 Cu 4 O 8 , and the Bi 2 Sr 2 Ca n-1 Cu n O 2+4 (n = 1, and 2) superconductors, and attempt to elucidate the atomic mechanisms responsible

Oxygen--a limiting factor for brain recovery.

Science.gov (United States)

Hadanny, Amir; Efrati, Shai

2015-09-01

Effective brain metabolism is highly dependent on a narrow therapeutic window of oxygen. In major insults to the brain (e.g., intracerebral hemorrhage), a slight decrease in oxygen supply, as occurs in a hypobaric environment at high altitude, has devastating effects on the injured brain tissue. Conversely, increasing brain oxygenation, by the use of hyperbaric oxygen therapy, can improve brain metabolism and its dependent regenerative processes.

Oxygen - a limiting factor for brain recovery

OpenAIRE

Hadanny, Amir; Efrati, Shai

2015-01-01

Effective brain metabolism is highly dependent on a narrow therapeutic window of oxygen. In major insults to the brain (e.g., intracerebral hemorrhage), a slight decrease in oxygen supply, as occurs in a hypobaric environment at high altitude, has devastating effects on the injured brain tissue. Conversely, increasing brain oxygenation, by the use of hyperbaric oxygen therapy, can improve brain metabolism and its dependent regenerative processes.

Quantification of photocatalytic oxygenation of human blood.

Science.gov (United States)

Subrahmanyam, Aryasomayajula; Thangaraj, Paul R; Kanuru, Chandrasekhar; Jayakumar, Albert; Gopal, Jayashree

2014-04-01

Photocatalytic oxygenation of human blood is an emerging concept based on the principle of photocatalytic splitting of water into oxygen and hydrogen. This communication reports: (i) a design of a photocatalytic cell (PC) that separates the blood from UV (incident) radiation source, (ii) a pH, temperature and flow controlled circuit designed for quantifying the oxygenation of human blood by photocatalysis and (iii) measuring the current efficacy of ITO/TiO2 nano thin films in oxygenating human blood in a dynamic circuit in real time. The average increase in oxygen saturation was around 5% above baseline compared to control (p<0.0005). We believe this is one of the first attempts to quantify photocatalytic oxygenation of human blood under controlled conditions. Copyright © 2013 IPEM. Published by Elsevier Ltd. All rights reserved.

Perceptions des patients pouvant influencer l’autonomisation en lien avec l’éducation à la santé tertiaire ainsi que les stratégies potentiellement autonomisantes : analyse de synthèse interprétative critique

Directory of Open Access Journals (Sweden)

Assumpta Ndengeyingoma

2014-07-01

Full Text Available Puisque la gestion d’une situation de santé serait quasi impossible sans que le patient acquière certaines compétences, ce texte explore les perceptions des patients pouvant influencer leur autonomisation en situation d’éducation tertiaire et identifie des stratégies potentiellement autonomisantes pour les adresser. L’approche synthèse interprétative critique fût utilisée. Trois perceptions des patients sont résumées : la perception d’être partenaire avec les professionnels, la perception de la compréhension de leur état et la perception de l’influence ou du contrôle de leur situation. Identification de stratégies de nature éducative et comportementale. Les perceptions des patients démontrent qu’ils ne se sentent pas aussi autonomisés que les professionnels pensent, alors il est recommandé de reconnaître les perceptions qui nuisent à l’autonomisation, ainsi que des stratégies pour les gérer. Ceci inclut la considération du niveau de littératie en santé du patient ainsi que l’utilisation accrue d’outils validés avec des méthodes qualitatives auprès de populations variées.

Comparison of pulseoximetry oxygen saturation and arterial oxygen saturation in open heart intensive care unit

Directory of Open Access Journals (Sweden)

Alireza Mahoori

2013-08-01

Full Text Available Background: Pulseoximetry is widely used in the critical care setting, currently used to guide therapeutic interventions. Few studies have evaluated the accuracy of SPO2 (puls-eoximetry oxygen saturation in intensive care unit after cardiac surgery. Our objective was to compare pulseoximetry with arterial oxygen saturation (SaO2 during clinical routine in such patients, and to examine the effect of mild acidosis on this relationship.Methods: In an observational prospective study 80 patients were evaluated in intensive care unit after cardiac surgery. SPO2 was recorded and compared with SaO2 obtained by blood gas analysis. One or serial arterial blood gas analyses (ABGs were performed via a radial artery line while a reliable pulseoximeter signal was present. One hundred thirty seven samples were collected and for each blood gas analyses, SaO2 and SPO2 we recorded.Results: O2 saturation as a marker of peripheral perfusion was measured by Pulseoxim-etry (SPO2. The mean difference between arterial oxygen saturation and pulseoximetry oxygen saturation was 0.12%±1.6%. A total of 137 paired readings demonstrated good correlation (r=0.754; P<0.0001 between changes in SPO2 and those in SaO2 in samples with normal hemoglobin. Also in forty seven samples with mild acidosis, paired readings demonstrated good correlation (r=0.799; P<0.0001 and the mean difference between SaO2 and SPO2 was 0.05%±1.5%.Conclusion: Data showed that in patients with stable hemodynamic and good signal quality, changes in pulseoximetry oxygen saturation reliably predict equivalent changes in arterial oxygen saturation. Mild acidosis doesn’t alter the relation between SPO2 and SaO2 to any clinically important extent. In conclusion, the pulse oximeter is useful to monitor oxygen saturation in patients with stable hemodynamic.

Oxygen dependency of germinating Brassica seeds

Science.gov (United States)

Park, Myoung Ryoul; Hasenstein, Karl H.

2016-02-01

Establishing plants in space, Moon or Mars requires adaptation to altered conditions, including reduced pressure and composition of atmospheres. To determine the oxygen requirements for seed germination, we imbibed Brassica rapa seeds under varying oxygen concentrations and profiled the transcription patterns of genes related to early metabolism such as starch degradation, glycolysis, and fermentation. We also analyzed the activity of lactate dehydrogenase (LDH) and alcohol dehydrogenase (ADH), and measured starch degradation. Partial oxygen pressure (pO2) greater than 10% resulted in normal germination (i.e., protrusion of radicle about 18 hours after imbibition) but lower pO2 delayed and reduced germination. Imbibition in an oxygen-free atmosphere for three days resulted in no germination but subsequent transfer to air initiated germination in 75% of the seeds and the root growth rate was transiently greater than in roots germinated under ambient pO2. In hypoxic seeds soluble sugars degraded faster but the content of starch after 24 h was higher than at ambient oxygen. Transcription of genes related to starch degradation, α-amylase (AMY) and Sucrose Synthase (SUS), was higher under ambient O2 than under hypoxia. Glycolysis and fermentation pathway-related genes, glucose phosphate isomerase (GPI), 6-phosphofructokinase (PFK), fructose 1,6-bisphosphate aldolase (ALD), glyceraldehyde-3-phosphate dehydrogenase (GAPDH), pyruvate decarboxylase (PDC), LDH, and ADH, were induced by low pO2. The activity of LDH and ADH was the highest in anoxic seeds. Germination under low O2 conditions initiated ethanolic fermentation. Therefore, sufficient oxygen availability is important for germination before photosynthesis provides necessary oxygen and the determination of an oxygen carrying capacity is important for uniform growth in space conditions.

Ocean Ridges and Oxygen

Science.gov (United States)

Langmuir, C. H.

2014-12-01

The history of oxygen and the fluxes and feedbacks that lead to its evolution through time remain poorly constrained. It is not clear whether oxygen has had discrete steady state levels at different times in Earth's history, or whether oxygen evolution is more progressive, with trigger points that lead to discrete changes in markers such as mass independent sulfur isotopes. Whatever this history may have been, ocean ridges play an important and poorly recognized part in the overall mass balance of oxidants and reductants that contribute to electron mass balance and the oxygen budget. One example is the current steady state O2 in the atmosphere. The carbon isotope data suggest that the fraction of carbon has increased in the Phanerozoic, and CO2 outgassing followed by organic matter burial should continually supply more O2 to the surface reservoirs. Why is O2 not then increasing? A traditional answer to this question would relate to variations in the fraction of burial of organic matter, but this fraction appears to have been relatively high throughout the Phanerozoic. Furthermore, subduction of carbon in the 1/5 organic/carbonate proportions would contribute further to an increasingly oxidized surface. What is needed is a flux of oxidized material out of the system. One solution would be a modern oxidized flux to the mantle. The current outgassing flux of CO2 is ~3.4*1012 moles per year. If 20% of that becomes stored organic carbon, that is a flux of .68*1012 moles per year of reduced carbon. The current flux of oxidized iron in subducting ocean crust is ~2*1012 moles per year of O2 equivalents, based on the Fe3+/Fe2+ ratios in old ocean crust compared to fresh basalts at the ridge axis. This flux more than accounts for the incremental oxidizing power produced by modern life. It also suggests a possible feedback through oxygenation of the ocean. A reduced deep ocean would inhibit oxidation of ocean crust, in which case there would be no subduction flux of oxidized

The Relevance of Humanitarian Intervention in the New ...

African Journals Online (AJOL)

They played a key role in restoring confidence among Burundians by insuring that the situation in the country did not degenerate into chaos. Their support towards the peace process ensured the implementation of the Arusha agreement for Burundi. La fin de la Guerre Froide a rendu possible un changement fondamental ...

Design Methods in Solid Rocket Motors. Revised Version 1988

Science.gov (United States)

1988-04-01

La necessite de faire Ie point de maniere periodique sur ces prob1emes est absolument evidente. On doit ajouter qu’il existe tres peu d’ouvrages de...structurales froides . Cependant, de nombreux problemes techniques et economiques restent a resoudre : assurance de la qua- lite, controle non destructif

rapid extraction of volatile compounds from citrus fruits using a ...

African Journals Online (AJOL)

M.A. Ferhat , M.N. Boukhatem, M. Hazzit 3, F.Chemat

1 sept. 2016 ... que l'industrie chimique utilise des procédés utilisant les propriétés thermiques spécifiques ... moins de solvant, moins d'énergie et diminuant les rejets. ...... expression à froid à l'aide d'un appareil d'extraction semi industriel ...

Thin film oxygen partial pressure sensor

Science.gov (United States)

Wortman, J. J.; Harrison, J. W.; Honbarrier, H. L.; Yen, J.

1972-01-01

The development is described of a laboratory model oxygen partial pressure sensor using a sputtered zinc oxide thin film. The film is operated at about 400 C through the use of a miniature silicon bar. Because of the unique resistance versus temperature relation of the silicon bar, control of the operational temperature is achieved by controlling the resistance. A circuit for accomplishing this is described. The response of sputtered zinc oxide films of various thicknesses to oxygen, nitrogen, argon, carbon dioxide, and water vapor caused a change in the film resistance. Over a large range, film conductance varied approximately as the square root of the oxygen partial pressure. The presence of water vapor in the gas stream caused a shift in the film conductance at a given oxygen partial pressure. A theoretical model is presented to explain the characteristic features of the zinc oxide response to oxygen.

29 CFR 1910.104 - Oxygen.

Science.gov (United States)

2010-07-01

...”, or an equivalent warning. (ix) Electrical wiring. Bulk oxygen installations are not hazardous... of electrical wiring and equipment are acceptable depending upon whether the installation is indoors... to the installation of bulk oxygen systems on industrial and institutional consumer premises. This...

Environmental science: Oceans lose oxygen

Science.gov (United States)

Gilbert, Denis

2017-02-01

Oxygen is essential to most life in the ocean. An analysis shows that oxygen levels have declined by 2% in the global ocean over the past five decades, probably causing habitat loss for many fish and invertebrate species. See Letter p.335

On the Go with Oxygen

Science.gov (United States)

... for both the patient and the oxygen supply company. There are two types of concentrators: Stationary concentrators plug into an electrical ... stationary unit. If your oxygen needs change, the type of system can ... supply company should explain and demonstrate whatever system you choose. ...

Oxygen Dependent Biocatalytic Processes

DEFF Research Database (Denmark)

Pedersen, Asbjørn Toftgaard

Enzyme catalysts have the potential to improve both the process economics and the environ-mental profile of many oxidation reactions especially in the fine- and specialty-chemical industry, due to their exquisite ability to perform stereo-, regio- and chemo-selective oxida-tions at ambient...... to aldehydes and ketones, oxyfunctionalization of C-H bonds, and epoxidation of C-C double bonds. Although oxygen dependent biocatalysis offers many possibilities, there are numerous chal-lenges to be overcome before an enzyme can be implemented in an industrial process. These challenges requires the combined...... far below their potential maximum catalytic rate at industrially relevant oxygen concentrations. Detailed knowledge of the en-zyme kinetics are therefore required in order to determine the best operating conditions and design oxygen supply to minimize processing costs. This is enabled...

Oxygen Exposure Resulting in Arterial Oxygen Tensions Above the Protocol Goal Was Associated With Worse Clinical Outcomes in Acute Respiratory Distress Syndrome.

Science.gov (United States)

Aggarwal, Neil R; Brower, Roy G; Hager, David N; Thompson, B Taylor; Netzer, Giora; Shanholtz, Carl; Lagakos, Adrian; Checkley, William

2018-04-01

High fractions of inspired oxygen may augment lung damage to exacerbate lung injury in patients with acute respiratory distress syndrome. Participants enrolled in Acute Respiratory Distress Syndrome Network trials had a goal partial pressure of oxygen in arterial blood range of 55-80 mm Hg, yet the effect of oxygen exposure above this arterial oxygen tension range on clinical outcomes is unknown. We sought to determine if oxygen exposure that resulted in a partial pressure of oxygen in arterial blood above goal (> 80 mm Hg) was associated with worse outcomes in patients with acute respiratory distress syndrome. Longitudinal analysis of data collected in these trials. Ten clinical trials conducted at Acute Respiratory Distress Syndrome Network hospitals between 1996 and 2013. Critically ill patients with acute respiratory distress syndrome. None. We defined above goal oxygen exposure as the difference between the fraction of inspired oxygen and 0.5 whenever the fraction of inspired oxygen was above 0.5 and when the partial pressure of oxygen in arterial blood was above 80 mm Hg. We then summed above goal oxygen exposures in the first five days to calculate a cumulative above goal oxygen exposure. We determined the effect of a cumulative 5-day above goal oxygen exposure on mortality prior to discharge home at 90 days. Among 2,994 participants (mean age, 51.3 yr; 54% male) with a study-entry partial pressure of oxygen in arterial blood/fraction of inspired oxygen that met acute respiratory distress syndrome criteria, average cumulative above goal oxygen exposure was 0.24 fraction of inspired oxygen-days (interquartile range, 0-0.38). Participants with above goal oxygen exposure were more likely to die (adjusted interquartile range odds ratio, 1.20; 95% CI, 1.11-1.31) and have lower ventilator-free days (adjusted interquartile range mean difference of -0.83; 95% CI, -1.18 to -0.48) and lower hospital-free days (adjusted interquartile range mean difference of -1.38; 95

Design of a lunar oxygen production plant

Science.gov (United States)

Radhakrishnan, Ramalingam

1990-01-01

To achieve permanent human presence and activity on the moon, oxygen is required for both life support and propulsion. Lunar oxygen production using resources existing on the moon will reduce or eliminate the need to transport liquid oxygen from earth. In addition, the co-products of oxygen production will provide metals, structural ceramics, and other volatile compounds. This will enable development of even greater self-sufficiency as the lunar outpost evolves. Ilmenite is the most abundant metal-oxide mineral in the lunar regolith. A process involving the reaction of ilmenite with hydrogen at 1000 C to produce water, followed by the electrolysis of this water to provide oxygen and recycle the hydrogen has been explored. The objective of this 1990 Summer Faculty Project was to design a lunar oxygen-production plant to provide 5 metric tons of liquid oxygen per year from lunar soil. The results of this study describe the size and mass of the equipment, the power needs, feedstock quantity and the engineering details of the plant.

Les soubresauts de la fusion froide

CERN Multimedia

Augereau, J F

1993-01-01

"En 1989, deux chercheurs avaient affirmé avoir découvert une nouvelle source d'énergie. Malgré le scepticisme de la communauté scientifique, ils persistent et signent un nouvel article sur la sujet".

High temperature microcalorimetry. Study of metal-oxygen systems

International Nuclear Information System (INIS)

Tetot, R.; Picard, C.; Boureau, G.; Gerdanian, P.

1981-01-01

Determination of partial molar enthalpy in metal-oxygen systems at 1050 0 C. Three representative systems are studied: the solution of oxygen in titanium, the titanium-oxygen system and the uranium-oxygen system from UOsub(2.00) to UOsub(2.60) [fr

CADDIS Volume 2. Sources, Stressors and Responses: Dissolved Oxygen

Science.gov (United States)

Introduction to the dissolved oxygen module, when to list dissolved oxygen as a candidate cause, ways to measure dissolved oxygen, simple and detailed conceptual model diagrams for dissolved oxygen, references for the dissolved oxygen module.

Optimizing oxygenation and intubation conditions during awake fibre-optic intubation using a high-flow nasal oxygen-delivery system.

Science.gov (United States)

Badiger, S; John, M; Fearnley, R A; Ahmad, I

2015-10-01

Awake fibre-optic intubation is a widely practised technique for anticipated difficult airway management. Despite the administration of supplemental oxygen during the procedure, patients are still at risk of hypoxia because of the effects of sedation, local anaesthesia, procedural complications, and the presence of co-morbidities. Traditionally used oxygen-delivery devices are low flow, and most do not have a sufficient reservoir or allow adequate fresh gas flow to meet the patient's peak inspiratory flow rate, nor provide an adequate fractional inspired oxygen concentration to prevent desaturation should complications arise. A prospective observational study was conducted using a high-flow humidified transnasal oxygen-delivery system during awake fibre-optic intubation in 50 patients with anticipated difficult airways. There were no episodes of desaturation or hypercapnia using the high-flow system, and in all patients the oxygen saturation improved above baseline values, despite one instance of apnoea resulting from over-sedation. All patients reported a comfortable experience using the device. The high-flow nasal oxygen-delivery system improves oxygenation saturation, decreases the risk of desaturation during the procedure, and potentially, optimizes conditions for awake fibre-optic intubation. The soft nasal cannulae uniquely allow continuous oxygenation and simultaneous passage of the fibrescope and tracheal tube. The safety of the procedure may be increased, because any obstruction, hypoventilation, or periods of apnoea that may arise may be tolerated for longer, allowing more time to achieve ventilation in an optimally oxygenated patient. © The Author 2015. Published by Oxford University Press on behalf of the British Journal of Anaesthesia. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

Late Archean Surface Ocean Oxygenation (Invited)

Science.gov (United States)

Kendall, B.; Reinhard, C.; Lyons, T. W.; Kaufman, A. J.; Anbar, A. D.

2009-12-01

Oxygenic photosynthesis must have evolved by 2.45-2.32 Ga, when atmospheric oxygen abundances first rose above 0.001% present atmospheric level (Great Oxidation Event; GOE). Biomarker evidence for a time lag between the evolution of cyanobacterial oxygenic photosynthesis and the GOE continues to be debated. Geochemical signatures from sedimentary rocks (redox-sensitive trace metal abundances, sedimentary Fe geochemistry, and S isotopes) represent an alternative tool for tracing the history of Earth surface oxygenation. Integrated high-resolution chemostratigraphic profiles through the 2.5 Ga Mt. McRae Shale (Pilbara Craton, Western Australia) suggest a ‘whiff’ of oxygen in the surface environment at least 50 M.y. prior to the GOE. However, the geochemical data from the Mt. McRae Shale does not uniquely constrain the presence or extent of Late Archean ocean oxygenation. Here, we present high-resolution chemostratigraphic profiles from 2.6-2.5 Ga black shales (upper Campbellrand Subgroup, Kaapvaal Craton, South Africa) that provide the earliest direct evidence for an oxygenated ocean water column. On the slope beneath the Campbellrand - Malmani carbonate platform (Nauga Formation), a mildly oxygenated water column (highly reactive iron to total iron ratios [FeHR/FeT] ≤ 0.4) was underlain by oxidizing sediments (low Re and Mo abundances) or mildly reducing sediments (high Re but low Mo abundances). After drowning of the carbonate platform (Klein Naute Formation), the local bottom waters became anoxic (FeHR/FeT > 0.4) and intermittently sulphidic (pyrite iron to highly reactive iron ratios [FePY/FeHR] > 0.8), conducive to enrichment of both Re and Mo in sediments, followed by anoxic and Fe2+-rich (ferruginous) conditions (high FeT, FePY/FeHR near 0). Widespread surface ocean oxygenation is suggested by Re enrichment in the broadly correlative Klein Naute Formation and Mt. McRae Shale, deposited ~1000 km apart in the Griqualand West and Hamersley basins

An atomic oxygen device based on PIG oxygen negative ion source

International Nuclear Information System (INIS)

Yu Jinxiang; Cai Minghui; Han Jianwei

2008-01-01

It is an important research subject for the spaceflight countries to conduct equivalent simulation of 5 eV atomic oxygen effects for the spaceflight material in low earth orbit. This paper introduces an apparatus used for producing atomic oxygen, which consists of a PIG ion source with permanent magnet, two electrodes extraction system, an electron deflector, an einzel lens, an ion decelerating electrode and a sample bracket. At present it has been used on the small debris accelerator in the Center for Space Science and Applied Research, Chinese Academy of Sciences, and the producing experiments of O - are carried out. 200-300μA of O - ions are extracted at the extraction voltage of 2-3 kV. The experiments for decelerating of O - ions and erosion of kapton foil are carried out also. Because of the target room used for both the atomic oxygen device and the small debris accelerator, the facility can be used for small debris impinging and atomic erosion for spaceflight materials simultaneously. (authors)

Oxygen treatment of cluster headache

DEFF Research Database (Denmark)

Petersen, Anja S; Barloese, Mads C J; Jensen, Rigmor H

2014-01-01

PURPOSE: Our aim was to review the existing literature to document oxygen's therapeutic effect on cluster headache. METHOD: A PubMed search resulted in 28 hits, and from these and their references we found in total 11 relevant studies. We included six studies that investigated the efficacy......, but not a prophylactic effect. Despite the fact that only a few high-quality RCT studies are available, oxygen treatment is close to an ideal treatment because it is effective and safe. However, sufferers of cluster headache do not always have access to oxygen because of logistic and financial concerns....

Real-Time Monitoring of Singlet Oxygen and Oxygen Partial Pressure During the Deep Photodynamic Therapy In Vitro.

Science.gov (United States)

Li, Weitao; Huang, Dong; Zhang, Yan; Liu, Yangyang; Gu, Yueqing; Qian, Zhiyu

2016-09-01

Photodynamic therapy (PDT) is an effective noninvasive method for the tumor treatment. The major challenge in current PDT research is how to quantitatively evaluate therapy effects. To our best knowledge, this is the first time to combine multi-parameter detection methods in PDT. More specifically, we have developed a set of system, including the high-sensitivity measurement of singlet oxygen, oxygen partial pressure and fluorescence image. In this paper, the detection ability of the system was validated by the different concentrations of carbon quantum dots. Moreover, the correlation between singlet oxygen and oxygen partial pressure with laser irradiation was observed. Then, the system could detect the signal up to 0.5 cm tissue depth with 660 nm irradiation and 1 cm tissue depth with 980 nm irradiation by using up-conversion nanoparticles during PDT in vitro. Furthermore, we obtained the relationship among concentration of singlet oxygen, oxygen partial pressure and tumor cell viability under certain conditions. The results indicate that the multi-parameter detection system is a promising asset to evaluate the deep tumor therapy during PDT. Moreover, the system might be potentially used for the further study in biology and molecular imaging.

Bulk manufacture of concentrated oxygen gas-filled microparticles for intravenous oxygen delivery.

Science.gov (United States)

Kheir, John N; Polizzotti, Brian D; Thomson, Lindsay M; O'Connell, Daniel W; Black, Katherine J; Lee, Robert W; Wilking, James N; Graham, Adam C; Bell, David C; McGowan, Francis X

2013-08-01

Self-assembling, concentrated, lipid-based oxygen microparticles (LOMs) have been developed to administer oxygen gas when injected intravenously, preventing organ injury and death from systemic hypoxemia in animal models. Distinct from blood substitutes, LOMs are a one-way oxygen carrier designed to rescue patients who experience life-threatening hypoxemia, as caused by airway obstruction or severe lung injury. Here, we describe methods to manufacture large quantities of LOMs using an in-line, recycling, high-shear homogenizer, which can create up to 4 liters of microparticle emulsion in 10 minutes, with particles containing a median diameter of 0.93 microns and 60 volume% of gas phase. Using this process, we screen 30 combinations of commonly used excipients for their ability to form stable LOMs. LOMs composed of DSPC and cholesterol in a 1:1 molar ratio are stable for a 100 day observation period, and the number of particles exceeding 10 microns in diameter does not increase over time. When mixed with blood in vitro, LOMs fully oxygenate blood within 3.95 seconds of contact, and do not cause hemolysis or complement activation. LOMs can be manufactured in bulk by high shear homogenization, and appear to have a stability and size profile which merit further testing. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Hyperbaric oxygen therapy in periodontal diseases

Directory of Open Access Journals (Sweden)

Swapna A. Mahale

2013-01-01

Full Text Available Hyperbaric oxygen (HBO 2 has been successfully used in several medical fields. The therapeutic effect is related to elevated partial oxygen pressure in the tissues. The pressure itself enhances oxygen solubility in the tissue fluids. HBO 2 has shown to affect angiogenesis, bone metabolism and bone turnover. Studies have been conducted to analyze the effects of HBO 2 therapy on periodontal disease. HBO 2 increases local oxygen distribution, especially at the base of the periodontal pocket, which inhibits the growth of anaerobic bacteria and allows the ischemic tissues to receive an adequate intake of oxygen sufficient for a rapid recovery of cell metabolism. It is increasingly being accepted as a beneficial adjunct to diverse clinical conditions. Nonhealing ulcers, chronic wounds and refractory osteomyelitis are a few conditions for which HBO therapy (HBOT has been extensively tried out. The dental surgeons have found a good ally in HBOT in managing dental condition.

Cooking and oxygen. An explosive recipe.

Science.gov (United States)

Burns, H L; Ralston, D; Muller, M; Pegg, S

2001-02-01

Home oxygen therapy is commonly prescribed for the treatment of chronic obstructive pulmonary disease (COPD). The risks of smoking while using this therapy have been well described. To discuss the Royal Brisbane Hospital Burns Unit's experience and present case studies which illustrate the danger of alternative ignition sources while using home oxygen. The dangers of home oxygen therapy can be minimised by careful patient selection, education and ongoing monitoring.

Fuel cell serves as oxygen level detector

Science.gov (United States)

1965-01-01

Monitoring the oxygen level in the air is accomplished by a fuel cell detector whose voltage output is proportional to the partial pressure of oxygen in the sampled gas. The relationship between output voltage and partial pressure of oxygen can be calibrated.

A rechargeable carbon-oxygen battery

DEFF Research Database (Denmark)

2014-01-01

The invention relates to a rechargeable battery and a method to operate a rechargeable battery having high efficiency and high energy density for storing energy. The battery stores electrical energy in the bonds of carbon and oxygen atoms by converting carbon dioxide into solid carbon and oxygen....

Misconceptions in Reporting Oxygen Saturation

NARCIS (Netherlands)

Toffaletti, John; Zijlstra, Willem G.

2007-01-01

BACKGROUND: We describe some misconceptions that have become common practice in reporting blood gas and cooximetry results. In 1980, oxygen saturation was incorrectly redefined in a report of a new instrument for analysis of hemoglobin (Hb) derivatives. Oxygen saturation (sO(2)) was redefined as the

Oxygen enhancement of groundwater using an oxygen releasing compound in a funnel-and-gate system

Energy Technology Data Exchange (ETDEWEB)

Thomas, D G

1994-01-01

ORC is a fine white MgO[sub 2] powder treated with a patented process so that a slow, relatively steady release of oxygen occurs when the powder is in contact with water. Recent work suggests ORC could potentially be used to increase the dissolved oxygen (DO) concentration of ground water, thereby enhancing the biodegradation of dissolved phase contaminants such as benzene and toluene from gasoline spills. Field and laboratory tests were performed to evaluate the oxygen release characteristics of ORC when mixed with filter sand and exposed to groundwater from an aquifer in Ontario. Quasi steady state oxygen release rates of 0.013-0.030 and 0.030 mg O[sub 2]/d per g of ORC were determined from the column and field tests respectively. The column tests indicated that steady state oxygen release conditions from the ORC required ca 90 d after initial contact with water, but field data indicated that oxygen release rate may continue to decrease. Falling head permeameter tests indicated that a maximum drop in hydraulic conductivity occurred within the first 48 h of exposure of ORC to water. Both laboratory and field studies indicated that ORC-contacted water increased in pH. Field studies further suggested an inverse correlation between pH increases and the ability of ORC to enhance DO concentration of ground water. The use of ORC in a funnel-and-gate scheme appears to be an effective means of increasing the DO concentration in ground water, thereby stimulating the in-situ bioremediation of many organic contaminants. 30 refs., 17 figs., 12 tabs.

Effects of normobaric versus hyperbaric oxygen on cell injury induced by oxygen and glucose deprivation in acute brain slices

OpenAIRE

Laurent Chazalviel; Jean-Eric Blatteau; Nicolas Vallée; Jean-Jacques Risso; Stéphane Besnard; Jacques H Abraini

2016-01-01

Normobaric oxygen (NBO) and hyperbaric oxygen (HBO) are emerging as a possible co-treatment of acute ischemic stroke. Both have been shown to reduce infarct volume, to improve neurologic outcome, to promote endogenous tissue plasminogen activator-induced thrombolysis and cerebral blood flow, and to improve tissue oxygenation through oxygen diffusion in the ischemic areas, thereby questioning the interest of HBO compared to NBO. In the present study, in order to investigate and compare the oxy...

Molecular Evolution of the Oxygen-Binding Hemerythrin Domain.

Directory of Open Access Journals (Sweden)

Claudia Alvarez-Carreño

Full Text Available The evolution of oxygenic photosynthesis during Precambrian times entailed the diversification of strategies minimizing reactive oxygen species-associated damage. Four families of oxygen-carrier proteins (hemoglobin, hemerythrin and the two non-homologous families of arthropodan and molluscan hemocyanins are known to have evolved independently the capacity to bind oxygen reversibly, providing cells with strategies to cope with the evolutionary pressure of oxygen accumulation. Oxygen-binding hemerythrin was first studied in marine invertebrates but further research has made it clear that it is present in the three domains of life, strongly suggesting that its origin predated the emergence of eukaryotes.Oxygen-binding hemerythrins are a monophyletic sub-group of the hemerythrin/HHE (histidine, histidine, glutamic acid cation-binding domain. Oxygen-binding hemerythrin homologs were unambiguously identified in 367/2236 bacterial, 21/150 archaeal and 4/135 eukaryotic genomes. Overall, oxygen-binding hemerythrin homologues were found in the same proportion as single-domain and as long protein sequences. The associated functions of protein domains in long hemerythrin sequences can be classified in three major groups: signal transduction, phosphorelay response regulation, and protein binding. This suggests that in many organisms the reversible oxygen-binding capacity was incorporated in signaling pathways. A maximum-likelihood tree of oxygen-binding hemerythrin homologues revealed a complex evolutionary history in which lateral gene transfer, duplications and gene losses appear to have played an important role.Hemerythrin is an ancient protein domain with a complex evolutionary history. The distinctive iron-binding coordination site of oxygen-binding hemerythrins evolved first in prokaryotes, very likely prior to the divergence of Firmicutes and Proteobacteria, and spread into many bacterial, archaeal and eukaryotic species. The later evolution of the

Etude de la stabilité globale de l’équilibre endémique des modèles multi groupes SIR avec une incidence non linéaire.

OpenAIRE

BENCHAIB, NESRINE

2014-01-01

Dans ce mémoire, on présente le nombre de reproduction de base pour un modèle épidémique multigroupe avec une incidence non linéaire. Ensuite, on établie la dynamique globale est entièrement déterminée par le nombre de reproduction de base R0. On montre que le nombre de reproduction de base R0 est un paramètre global de seuil dans le sens que si il est inférieur ou égale à 1, l’équilibre sans maladie est globalement stable et la maladie s’éteint, alors que si il est supérieur à 1, il est u...

Coping with cyclic oxygen availability: evolutionary aspects.

Science.gov (United States)

Flück, Martin; Webster, Keith A; Graham, Jeffrey; Giomi, Folco; Gerlach, Frank; Schmitz, Anke

2007-10-01

Both the gradual rise in atmospheric oxygen over the Proterozoic Eon as well as episodic fluctuations in oxygen over several million-year time spans during the Phanerozoic Era, have arguably exerted strong selective forces on cellular and organismic respiratory specialization and evolution. The rise in atmospheric oxygen, some 2 billion years after the origin of life, dramatically altered cell biology and set the stage for the appearance of multicelluar life forms in the Vendian (Ediacaran) Period of the Neoproterozoic Era. Over much of the Paleozoic, the level of oxygen in the atmosphere was near the present atmospheric level (21%). In the Late Paleozoic, however, there were extended times during which the level of atmospheric oxygen was either markedly lower or markedly higher than 21%. That these Paleozoic shifts in atmospheric oxygen affected the biota is suggested by the correlations between: (1) Reduced oxygen and the occurrences of extinctions, a lowered biodiversity and shifts in phyletic succession, and (2) During hyperoxia, the corresponding occurrence of phenomena such as arthropod gigantism, the origin of insect flight, and the evolution of vertebrate terrestriality. Basic similarities in features of adaptation to hyopoxia, manifest in living organisms at levels ranging from genetic and cellular to physiological and behavioral, suggest the common and early origin of a suite of adaptive mechanisms responsive to fluctuations in ambient oxygen. Comparative integrative approaches addressing the molecular bases of phenotypic adjustments to cyclic oxygen fluctuation provide broad insight into the incremental steps leading to the early evolution of homeostatic respiratory mechanisms and to the specialization of organismic respiratory function.

Simultaneous Monitoring of Vascular Oxygenation and Tissue Oxygen Tension of Breast Tumors Under Hyperbaric Oxygen Exposure

National Research Council Canada - National Science Library

Xia, Mengna

2005-01-01

The goals of the study in the first stage are 1) to develop a mathematic model by which we can derive tumor blood flow and metabolic rate of oxygen from hemoglobin concentration during interventions, 2...

14 CFR 23.1441 - Oxygen equipment and supply.

Science.gov (United States)

2010-01-01

... 14 Aeronautics and Space 1 2010-01-01 2010-01-01 false Oxygen equipment and supply. 23.1441... Miscellaneous Equipment § 23.1441 Oxygen equipment and supply. (a) If certification with supplemental oxygen..., during the flight, the quantity of oxygen available in each source of supply. (d) Each required flight...

Résultats de recherche | Page 412 | CRDI - Centre de recherches ...

International Development Research Centre (IDRC) Digital Library (Canada)

"Chaque fusil fabriqué, chaque navire de guerre lancé, chaque fusée envoyée signifie, au bout du compte, un vol de ceux qui ont faim et qui manquent de nourriture, de ceux qui ont froid et qui manquent de vêtements." Publication Date. 1 janvier 1998. Livres ...

Oxygen: the two-faced elixir of life.

Science.gov (United States)

Biddle, Chuck

2008-02-01

Take a moment and consider our planet without oxygen. Imagine the earth some 2.5 billion years ago when oxygen first appeared as a waste product of early anaerobes. Oxygen, as we know it today, is essential for life. Abundant and relatively inexpensive to manufacture, oxygen has widespread use in industry and healthcare. Anesthesia providers routinely administer oxygen in concentrations exceeding that in ambient air to ensure clinical safety and to offset the predictable sequelae associated with patient, drug-related, and procedural factors. Understanding the history of this unique element is critical in evaluating the often contentious body of contemporary research that has illuminated its efficacy (as elixir) and its attendant complications (its "two-faced" nature). Of particular interest is its role in free radical formation as etiogenic in developing complications. Oxygen is a mainstay in the perioperative management of patients, but its administration should be guided by thoughtful and rational goal-directed outcomes to maximize efficacy and minimize complications associated with its use.

Brain oxygen saturation assessment in neonates using T2-prepared blood imaging of oxygen saturation and near-infrared spectroscopy

DEFF Research Database (Denmark)

Alderliesten, Thomas; De Vis, Jill B; Lemmers, Petra Ma

2017-01-01

saturation in the sagittal sinus (R(2 )= 0.49, p = 0.023), but no significant correlations could be demonstrated with frontal and whole brain cerebral blood flow. These results suggest that measuring oxygen saturation by T2-prepared blood imaging of oxygen saturation is feasible, even in neonates. Strong...... sinus. A strong linear relation was found between the oxygen saturation measured by magnetic resonance imaging and the oxygen saturation measured by near-infrared spectroscopy (R(2 )= 0.64, p ..., and magnetic resonance imaging measures of frontal cerebral blood flow, whole brain cerebral blood flow and venous oxygen saturation in the sagittal sinus (R(2 )= 0.71, 0.50, 0.65; p 

Oxygen injection facility

International Nuclear Information System (INIS)

Ota, Masamoto; Hirose, Yuki

1998-01-01

A compressor introduces air as a starting material and sends it to a dust removing device, a dehumidifying device and an adsorption/separation system disposed downstream. The facility of the present invention is disposed in the vicinity of an injection point and installed in a turbine building of a BWR type reactor having a pipeline of a feedwater system to be injected. The adsorbing/separation system comprises an adsorbing vessel and an automatic valve, and the adsorbing vessel is filled with an adsorbent for selectively adsorbing nitrogen. Zeolite is used as the adsorbent. Nitrogen in the air passing through the adsorbing vessel is adsorbed and removed under a pressurized condition, and a highly concentrated oxygen gas is formed. The direction of the steam of the adsorbed nitrogen is changed by an opening/closing switching operation of an automatic valve and released to the atmosphere (the pressure is released). Generated oxygen gas is stored under pressure in a tank, and injected to the pipeline of the feedwater system by an oxygen injection conduit by way of a flow rate control valve. In the adsorbing vessel, steps of adsorption, separation and storage under pressure are repeated successively. (I.N.)

Oxygenation and cracking in melt-textured YBCO bulk superconductors

International Nuclear Information System (INIS)

Kracunovska, S; Diko, P; Litzkendorf, D; Habisreuther, T; Bierlich, J; Gawalek, W

2005-01-01

Microstructural changes during the oxygenation of YBCO bulks were studied. It was shown that a lower temperature of oxygenation leads to the formation of a denser structure of a/b- and c-macrocracks and causes faster and more homogeneous oxygenation of the sample. The opening of created macrocracks is the way in which the macroscopic stresses induced by macroscopic 211 particle concentration inhomogeneity are released. This is very important, because it prevents the formation of fatal c-macrocracks, which divide the sample into more domains, during cooling from oxygenation temperature or during sample performance. Oxygenation with a multistage programme causes the oxygen concentration difference between the oxygenated layer and the tetragonal matrix to be smaller, and consequently fewer macrocracks are formed. This leads to the prolongation of oxygenation times for full oxygenation and to the insufficient release of macroscopic stresses. 211 low concentration regions and pores also enhance the oxygenation rate of YBCO bulks

Oxygen consumption in EPDM irradiated under different oxygen pressures and at different LET

International Nuclear Information System (INIS)

Dely, N.; Ngono-Ravache, Y.; Ramillon, J.-M.; Balanzat, E.

2005-01-01

We conceived a novel set-up for measuring the radiochemical yields of oxygen consumption in polymers. The measurement is based on a sampling of the gas mixture with a mass spectrometer, before and after irradiation. We irradiated an ethylene, propylene and 1,4-hexadiene terpolymer (EPDM) with 1 MeV electron and 10.75 MeV/A carbon beams. Samples were irradiated under oxygen within a wide range of pressure (5-200 mbar). The yields under C irradiation are four times smaller than the yields under electron irradiation. This shows that radiooxidation is very sensitive to the linear energy transfer of the projectiles and hence to the heterogeneity of the energy deposition. The oxygen consumption yields do not vary significantly in the range of pressure investigated; even at 5 mbar, the kinetics is still governed by the bimolecular recombination of peroxy radicals

Comparison of the OxyMask and Venturi mask in the delivery of supplemental oxygen: Pilot study in oxygen-dependent patients

Science.gov (United States)

Beecroft, Jaime M; Hanly, Patrick J

2006-01-01

BACKGROUND: The OxyMask (Southmedic Inc, Canada) is a new face mask for oxygen delivery that uses a small ‘diffuser’ to concentrate and direct oxygen toward the mouth and nose. The authors hypothesized that this unique design would enable the OxyMask to deliver oxygen more efficiently than a Venturi mask (Hudson RCI, USA) in patients with chronic hypoxemia. METHODS: Oxygen-dependent patients with chronic, stable respiratory disease were recruited to compare the OxyMask and Venturi mask in a randomized, single-blind, cross-over design. Baseline blood oxygen saturation (SaO2) was established breathing room air, followed in a random order by supplemental oxygen through the OxyMask or Venturi mask. Oxygen delivery was titrated to maintain SaO2 4% to 5% and 8% to 9% above baseline for two separate 30 min periods of stable breathing. Oxygen flow rate, partial pressure of inspired and expired oxygen (PO2) and carbon dioxide (PCO2), minute ventilation, heart rate, nasal and oral breathing, SaO2 and transcutaneous PCO2 were collected continuously. The study was repeated following alterations to the OxyMask design, which improved clearance of carbon dioxide. RESULTS: Thirteen patients, aged 28 to 79 years, were studied initially using the original OxyMask. Oxygen flow rate was lower, inspired PO2 was higher and expired PO2 was lower while using the OxyMask. Minute ventilation and inspired and expired PCO2 were significantly higher while using the OxyMask, whereas transcutaneous PCO2, heart rate and the ratio of nasal to oral breathing did not change significantly throughout the study. Following modification of the OxyMask, 13 additional patients, aged 18 to 79 years, were studied using the same protocol. The modified OxyMask provided a higher inspired PO2 at a lower flow rate, without evidence of carbon dioxide retention. CONCLUSIONS: Oxygen is delivered safely and more efficiently by the OxyMask than by the Venturi mask in stable oxygen-dependent patients. PMID:16896425

[The oxygen consumption of ostrich embryos during incubation].

Science.gov (United States)

Reiner, G; Dzapo, V

1995-02-01

This work deals with the oxygen consumption of ostrich chicks during incubation. Brood eggs were incubated in a hermetic isolated acrylic-glass cylinder. Reduction of oxygen content in the air surrounding the egg was measured using an oxygen-sensitive electrode. A sigmoid curve could be drawn during incubation, with the steepest phase being around day 26. Maximum oxygen consumption was reached on day 36. It was slightly decreased until day 39, when the embryo switches to lung circulation, followed again by an increase until hatching. Average oxygen consumptions for the whole brood interval were calculated to 63.6 liters. Oxygen volumes consumed on day 36 result in a demand about to 240 liters of fresh air per egg and day. Oxygen consumption of the embryos on day 36 was significantly positive correlated with their vitality. Numb or less vital embryos could be clearly differentiated from others. The higher a chick's oxygen consumption, the earlier and shorter its hatching. Possible applications of the method in regard to the evaluation of incubation parameters or chicken constitution are discussed.

Formation and Migration of Oxygen Vacancies in SrCoO3 and their effect on Oxygen Evolution Reactions

KAUST Repository

Tahini, Hassan A.; Tan, Xin; Schwingenschlö gl, Udo; Smith, Sean C.

2016-01-01

Perovskite SrCoO3 is a potentially useful material for promoting the electrocatalytic oxygen evolution reaction, with high activities predicted theoretically and observed experimentally for closely related doped perovskite materials. However, complete stoichiometric oxidation is very difficult to realize experimentally – in almost all cases there are significant fractions of oxygen vacancies present. Here, using first principles calculations we study oxygen vacancies in perovskite SrCoO3 from thermodynamic, electronic and kinetic points of view. We find that an oxygen vacancy donates two electrons to neighboring Co sites in the form of localized charge. The formation energy of a single vacancy is very low and estimated to be 1.26 eV in the dilute limit. We find that a vacancy is quite mobile with a migration energy of ~0.5 eV. Moreover, we predict that oxygen vacancies exhibit a tendency towards clustering which is in accordance with the material’s ability to form a variety of oxygen-deficient structures. These vacancies have a profound effect on the material’s ability to facilitate OER, increasing the overpotential from ~0.3 V for the perfect material to ~0.7 for defective surfaces. A moderate compressive biaxial strain (2%) is predicted here to increase the surface oxygen vacancy formation energy by ca. 30%, thus reducing the concentration of surface vacancies and thereby preserving the OER activity of the material.

Formation and Migration of Oxygen Vacancies in SrCoO3 and their effect on Oxygen Evolution Reactions

KAUST Repository

Tahini, Hassan A.

2016-07-18

Perovskite SrCoO3 is a potentially useful material for promoting the electrocatalytic oxygen evolution reaction, with high activities predicted theoretically and observed experimentally for closely related doped perovskite materials. However, complete stoichiometric oxidation is very difficult to realize experimentally – in almost all cases there are significant fractions of oxygen vacancies present. Here, using first principles calculations we study oxygen vacancies in perovskite SrCoO3 from thermodynamic, electronic and kinetic points of view. We find that an oxygen vacancy donates two electrons to neighboring Co sites in the form of localized charge. The formation energy of a single vacancy is very low and estimated to be 1.26 eV in the dilute limit. We find that a vacancy is quite mobile with a migration energy of ~0.5 eV. Moreover, we predict that oxygen vacancies exhibit a tendency towards clustering which is in accordance with the material’s ability to form a variety of oxygen-deficient structures. These vacancies have a profound effect on the material’s ability to facilitate OER, increasing the overpotential from ~0.3 V for the perfect material to ~0.7 for defective surfaces. A moderate compressive biaxial strain (2%) is predicted here to increase the surface oxygen vacancy formation energy by ca. 30%, thus reducing the concentration of surface vacancies and thereby preserving the OER activity of the material.

Optic nerve oxygen tension

DEFF Research Database (Denmark)

la Cour, M; Kiilgaard, Jens Folke; Eysteinsson, T

2000-01-01

To investigate the influence of acute changes in intraocular pressure on the oxygen tension in the vicinity of the optic nerve head under control conditions and after intravenous administration of 500 mg of the carbonic anhydrase inhibitor dorzolamide.......To investigate the influence of acute changes in intraocular pressure on the oxygen tension in the vicinity of the optic nerve head under control conditions and after intravenous administration of 500 mg of the carbonic anhydrase inhibitor dorzolamide....

The use of oxygen in hazardous waste incineration

International Nuclear Information System (INIS)

Ho, M.D.; Ding, M.G.

1989-01-01

The use of advanced oxygen combustion technologies in hazardous waste (such as PCBs and hydrocarbons) incineration has emerged in the last two years as one of the most significant breakthroughs among all the competing treatment technologies. For many years, industrial furnaces have used oxygen enrichment of the combustion air and oxygen-fuel burners, but with conventional technologies a high oxygen level generally poses problems. The flame temperature is high, leading to high NOx formation and local overeating. Different technical approaches to overcome these problems and their respective effectiveness will be reviewed. Previously, commercial oxygen enrichment in incinerators was limited to a rather modest level applications of much higher oxygen enrichment levels in hazardous waste incinerators

Lithium-Oxygen Batteries: At a Crossroads?

DEFF Research Database (Denmark)

Vegge, Tejs; García Lastra, Juan Maria; Siegel, Donald Jason

2017-01-01

In this current opinion, we critically review and discuss some of the most important recent findings in the field of rechargeable lithium-oxygen batteries. We discuss recent discoveries like the evolution of reactive singlet oxygen and the use of organic additives to bypass reactive LiO2 reaction...... intermediates, and their possible implications on the potential for commercialization of lithium-oxygen batteries. Finally, we perform a critical assessment of lithium-superoxide batteries and the reversibility of lithium-hydroxide batteries....

Oxygen consumption by hydrazine in long sample lines

International Nuclear Information System (INIS)

Chi, Lisheng; Turner, Carl-W.

2012-09-01

In nuclear power plants secondary side system dissolved oxygen concentration is a strictly controlled chemistry parameter intended to minimize corrosion and fouling of steam cycle components. Low dissolved oxygen concentration is maintained by a combination of mechanical de-aeration and chemical reaction. The dissolved oxygen concentration in feedwater is monitored by sampling systems to ensure it remains within station specification during operation. The sample lines in a nuclear power plant's sampling system can be from 5 to nearly 200 meters in length, resulting in sample residence times between the take-off point to the analyzer from a few seconds to several minutes, depending on the flow rate and the length of the sample line. For many chemical parameters the residence time is of no concern. For measurements of dissolved oxygen and hydrazine in the secondary coolant, however, for residence times longer than one minute, it is uncertain whether the sample is representative of conditions in the secondary coolant, especially for samples taken from locations where the temperature is well over 100 deg. C. To address this concern, a series of tests were conducted under both warm-up and power operation conditions, respectively, to investigate the effect of temperature, residence time, sample line length, surface area, hydrazine-to-oxygen ratio, and the concentrations of dissolved oxygen and hydrazine on the consumption of oxygen by hydrazine. The test results revealed that dissolved oxygen measurements in CANDU plants are underestimated to various degrees, depending on the sampling system operating conditions. Two distinct types of behaviours are observed for the oxygen removal rate: 1) the percentage removal of dissolved oxygen is invariant with time during the tests, and increases with increasing residence time in the test section, when the reaction between hydrazine and oxygen is better described by a homogenous reaction mechanism, and 2) the percentage oxygen

Oxygen regulation of nitrate uptake in denitrifying Pseudomonas aeruginosa.

OpenAIRE

Hernandez, D; Rowe, J J

1987-01-01

Oxygen had an immediate and reversible inhibitory effect on nitrate respiration by denitrifying cultures of Pseudomonas aeruginosa. Inhibition of nitrate utilization by oxygen appeared to be at the level of nitrate uptake, since nitrate reduction to nitrite in cell extracts was not affected by oxygen. The degree of oxygen inhibition was dependent on the concentration of oxygen, and increasing nitrate concentrations could not overcome the inhibition. The inhibitory effect of oxygen was maximal...

Clinical oxygen enhancement ratio of tumors in carbon ion radiotherapy: the influence of local oxygenation changes

DEFF Research Database (Denmark)

Antonovic, Laura; Lindblom, Emely; Dasu, Alexandru

2014-01-01

, using the repairable–conditionally repairable (RCR) damage model with parameters for human salivary gland tumor cells. The clinical oxygen enhancement ratio (OER) was defined as the ratio of doses required for a tumor control probability of 50% for hypoxic and well-oxygenated tumors. The resulting OER...... was well above unity for all fractionations. For the hypoxic tumor, the tumor control probability was considerably higher if LOCs were assumed, rather than static oxygenation. The beneficial effect of LOCs increased with the number of fractions. However, for very low fraction doses, the improvement related...... to LOCs did not compensate for the increase in total dose required for tumor control. In conclusion, our results suggest that hypoxia can influence the outcome of carbon ion radiotherapy because of the non-negligible oxygen effect at the low LETs in the SOBP. However, if LOCs occur, a relatively high...

Insights into the importance of oxygen functional groups in carbon reactions with oxygen containing gases

International Nuclear Information System (INIS)

John Zhu, Max Lu

2005-01-01

The role of pore structure of carbon in carbon-related adsorptions and reactions has been extensively investigated. However the studies on the role of surface chemistry of carbon are limited. In this paper, we present the importance of oxygen functional groups in carbon reactions with oxygen-containing gases. It is found that there is a good correlation between the electronic structures and reactivities of carbon edge sites. Zigzag sites are more active in oxygen adsorption because of the unpaired electrons and armchair sites are less active in oxygen adsorption due to the triple character. However, the desorption of semi-quinone oxygen from zigzag sites needs a bond energy ca. 30% higher than that of o-quinone oxygen from armchair edge sites. CO 2 and H 2 O adsorb on carbon surface much less favorably than O 2 . H 2 O is first physically adsorbed on the virgin graphite surface followed by chemisorption through oxygen atom approaching the carbon edge site and the movements of two hydrogen atoms to produce H 2 . The adsorption mechanism of H 2 O is different from that for CO 2 , but the final result is quite similar, i.e. producing only semi-quinone oxygen. Based upon the above studies, a new generalized mechanism, as shown in Fig. 1, is developed and can account for all the important kinetic phenomena of carbon-gas reactions. The key point is that in CO 2 /H 2 O-carbon reaction only semi-quinone formed; while, in O 2 -carbon reaction, semi-quinone, o-quinone (at lower pressure), and off-plane epoxy oxygen (at relatively higher pressure) can be formed. This is the main reason for the different reaction kinetics of O 2 -carbon reaction and CO 2 /H 2 O-carbon reactions as observed experimentally. The oxygen functional groups of carbon can be characterized by XPS, PZC (point of zero charge), IEP (isoelectric point) and TPD (temperature-programmed desorption), which were used in our previous studies. We treated the carbon surface with different acids, finding that HNO 3

Comportement des matériaux organiques vis-à-vis des carburants oxygénés The Behavior of Organic Materials with Regard to Oxygenated Fuels

Directory of Open Access Journals (Sweden)

Puisais M.

2006-11-01

Full Text Available Les incidences d'emploi des produits oxygénés dans les carburants ont été déterminées sur la tenue des principaux matériaux polymères utilisés dans les véhicules et les équipements de distribution. Des carburants renferment diverses teneurs en éthanol ou en méthanol, éventuellement en conjonction avec des co-solvants tels que le tertiobutanol ou un mélange acétonobutylique ont été examinés. Les méthodes d'essais appliquées ont permis de déterminer le comportement à long terme des matériaux au niveau de leur perméabilité, gonflement, vieillissement, fissuration sous contraintes, extraction et résistance à l'ozone. The effects of using oxygenated products in gasolines have been determined concerning the resistance of the leading polymer materials used in vehicles and distribution equipment. Fuels containing varying amounts of ethanol or methanol, possibly in conjunction with cosolvents such as tertiobutanol or a butanol-acetone mixture, have been examined. The test methods applied have determined the long-term behavior of materials with regard to their permeability, swelling, aging, stress cracking, extraction and ozone resistance.

46 CFR 147.85 - Oxygen.

Science.gov (United States)

2010-10-01

... 46 Shipping 5 2010-10-01 2010-10-01 false Oxygen. 147.85 Section 147.85 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) DANGEROUS CARGOES HAZARDOUS SHIPS' STORES Stowage and Other...) of oxygen may be on board a vessel engaged in industrial operations, if it is stowed on deck or in a...

Oxygen diffusion in monazite

Science.gov (United States)

Cherniak, D. J.; Zhang, X. Y.; Nakamura, M.; Watson, E. B.

2004-09-01

We report measurements of oxygen diffusion in natural monazites under both dry, 1-atm conditions and hydrothermal conditions. For dry experiments, 18O-enriched CePO4 powder and monazite crystals were sealed in Ag-Pd capsules with a solid buffer (to buffer at NNO) and annealed in 1-atm furnaces. Hydrothermal runs were conducted in cold-seal pressure vessels, where monazite grains were encapsulated with 18O-enriched water. Following the diffusion anneals, oxygen concentration profiles were measured with Nuclear Reaction Analysis (NRA) using the reaction 18O(p,α)15N. Over the temperature range 850-1100 °C, the Arrhenius relation determined for dry diffusion experiments on monazite is given by: Under wet conditions at 100 MPa water pressure, over the temperature range 700-880 °C, oxygen diffusion can be described by the Arrhenius relationship: Oxygen diffusion under hydrothermal conditions has a significantly lower activation energy for diffusion than under dry conditions, as has been found the case for many other minerals, both silicate and nonsilicate. Given these differences in activation energies, the differences between dry and wet diffusion rates increase with lower temperatures; for example, at 600 °C, dry diffusion will be more than 4 orders of magnitude slower than diffusion under hydrothermal conditions. These disparate diffusivities will result in pronounced differences in the degree of retentivity of oxygen isotope signatures. For instance, under dry conditions (presumably rare in the crust) and high lower-crustal temperatures (∼800 °C), monazite cores of 70-μm radii will preserve O isotope ratios for about 500,000 years; by comparison, they would be retained at this temperature under wet conditions for about 15,000 years.

Safety Standard for Oxygen and Oxygen Systems: Guidelines for Oxygen System Design, Materials Selection, Operations, Storage, and Transportation

Science.gov (United States)

1996-01-01

NASA's standard for oxygen system design, materials selection, operation, and transportation is presented. Minimum guidelines applicable to NASA Headquarters and all NASA Field Installations are contained.

Oxygen requirement of separated hybrid catfish eggs

Science.gov (United States)

Channel catfish egg masses require hatchery water with over 7.8 ppm dissolved oxygen at 80° F (95% air saturation) to maintain maximum oxygen consumption as they near hatching. This concentration is called the critical oxygen requirement by scientists but for the purpose of this article we will call...

Dynamic oxygen-enhanced MRI of cerebrospinal fluid.

Directory of Open Access Journals (Sweden)

Taha M Mehemed

Full Text Available Oxygen causes an increase in the longitudinal relaxation rate of tissues through its T1-shortening effect owing to its paramagnetic properties. Due to such effects, MRI has been used to study oxygen-related signal intensity changes in various body parts including cerebrospinal fluid (CSF space. Oxygen enhancement of CSF has been mainly studied using MRI sequences with relatively longer time resolution such as FLAIR, and T1 value calculation. In this study, fifteen healthy volunteers were scanned using fast advanced spin echo MRI sequence with and without inversion recovery pulse in order to dynamically track oxygen enhancement of CSF. We also focused on the differences of oxygen enhancement at sulcal and ventricular CSF. Our results revealed that CSF signal after administration of oxygen shows rapid signal increase in both sulcal CSF and ventricular CSF on both sequences, with statistically significant predominant increase in sulcal CSF compared with ventricular CSF. CSF is traditionally thought to mainly form from the choroid plexus in the ventricles and is absorbed at the arachnoid villi, however, it is also believed that cerebral arterioles contribute to the production and absorption of CSF, and controversy remains in terms of the precise mechanism. Our results demonstrated rapid oxygen enhancement in sulcal CSF, which may suggest inhaled oxygen may diffuse into sulcal CSF space rapidly probably due to the abundance of pial arterioles on the brain sulci.

The reactions of magnesium and its alloys with moist gases at high temperatures; Les reactions du magnesium et de ses alliages avec les gaz humides aux temperatures elevees

Energy Technology Data Exchange (ETDEWEB)

Darras, R [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1963-02-15

The kinetics and mechanisms of the reaction of pure or low alloyed magnesium with various gas saturated by water vapor: oxygen, argon, nitrogen, air, carbon dioxide, have been studied and compared in the temperature range 350-600 deg C. After picturing the large chemical reactivity of magnesium surface, the more or less properties of the oxide film, always made of magnesia, have been shown depending on the nature of the gas carrying water vapor; in fact, metal sublimation occurs the more easily as the surrounding atmosphere is less oxidizing. Moreover, an activation energy change is systematic, but at a temperature which depends also on the latter. In the case of the alloys, the linear oxidation rate is generally obtained only after short induction periods, parabolic in nature. Two possibilities of corrosion inhibition of magnesium by water vapor are then demonstrated and explained: either by a partial superficial fluoridation, or when the carrier gas is carbon dioxide. Also, the extreme conditions of oxidation were studied, that is the ignition processes that occur at a particular temperature in every gas mixture. Finally, it is tried to evolve the fundamental and practical significance of all the results. (author) [French] On a etudie et compare par voie thermogravimetrique, micrographique et radiocristallographique, les cinetiques et les mecanismes de reaction du magnesium et de certains de ses alliages avec diverses atmospheres saturees en vapeur d'eau: oxygene, argon, azote, air, gaz carbonique, dans un domaine de temperatures s'etendant de 350 a 600 deg C, Apres avoir illustre l'extreme sensibilite chimique de la surface du magnesium, on a tout d'abord montre que la valeur plus ou moins protectrice de la couche d'oxyde formee, pourtant toujours constituee de magnesie normale, depend de la nature du gaz porteur de la vapeur d'eau; en effet, la sublimation du metal intervient d'autant plus facilement que les atmospheres en presence sont moins oxydantes. De plus

Título do sítio electrónico: Fédération Européenne des Associations Nacionales Travaillant avec les Sans-Abri e European Observatory on Homelessness

Directory of Open Access Journals (Sweden)

João Aldeia

2012-10-01

Full Text Available Optou-se por apresentar conjuntamente as duas páginas pela sua estreita articulação temática e institucional. Criada em 1989, a FEANTSA – Fédération Européenne des Associations Nacionales Travaillant avec les Sans-Abri – é uma organização não-governamental (ONG dedicada a eliminar a pobreza e exclusão social de indivíduos sem-abrigo ou em risco de conhecer esta situação, que congrega mais de 100 ONGs locais e nacionais de vários Estados-membros da União Europeia, sendo financiada pela Comiss...

The surface chemistry of metal-oxygen interactions

DEFF Research Database (Denmark)

Stokbro, Kurt; Baroni, Stefano

1997-01-01

We report on a computational study of the clean and oxygen-covered Rh(110) surface, based on density-functional theory within the local-density approximation. We have used plane-wave basis sets and Vanderbilt ultra-soft pseudopotentials. For the clean surface, we present results for the equilibrium...... structure, surface energy and surface stress of the unreconstructed and (1 x 2) reconstructed structures. For the oxygen-covered surface we have performed a geometry optimization at 0.5, 1, and 2 monolayer oxygen coverages, and we present results for the equilibrium configurations, workfunctions and oxygen...

Evolution of factors affecting placental oxygen transfer

DEFF Research Database (Denmark)

Carter, A M

2009-01-01

A review is given of the factors determining placental oxygen transfer and the oxygen supply to the fetus. In the case of continuous variables, such as the rate of placental blood flow, it is not possible to trace evolutionary trends. Discontinuous variables, for which we can define character sta......, where fetal and adult haemoglobin are not different, developmental regulation of 2, 3-diphosphoglycerate ensures the high oxygen affinity of fetal blood. Oxygen diffusing capacity is dependent on diffusion distance, which may vary with the type of interhaemal barrier. It has been shown...

Oxygen safety

Science.gov (United States)

... sure you have working smoke detectors and a working fire extinguisher in your home. If you move around the house with your oxygen, you may need more than one fire extinguisher in different locations. Smoking can be very dangerous. No one should smoke ...

Oxygen tension level and human viral infections

Energy Technology Data Exchange (ETDEWEB)

Morinet, Frédéric, E-mail: frederic.morinet@sls.aphp.fr [Centre des Innovations Thérapeutiques en Oncologie et Hématologie (CITOH), CHU Saint-Louis, Paris (France); Université Denis Diderot, Sorbonne Paris Cité Paris, Paris (France); Casetti, Luana [Institut Cochin INSERM U1016, Paris (France); François, Jean-Hugues; Capron, Claude [Institut Cochin INSERM U1016, Paris (France); Laboratoire d' Hématologie, Hôpital Ambroise Paré, Boulogne (France); Université de Versailles Saint-Quentin en Yvelynes, Versailles (France); Pillet, Sylvie [Laboratoire de Bactériologie-Virologie-Hygiène, CHU de Saint-Etienne, Saint-Etienne (France); Université de Lyon et Université de Saint-Etienne, Jean Monnet, GIMAP EA3064, F-42023 Saint-Etienne, Lyon (France)

2013-09-15

The role of oxygen tension level is a well-known phenomenon that has been studied in oncology and radiotherapy since about 60 years. Oxygen tension may inhibit or stimulate propagation of viruses in vitro as well as in vivo. In turn modulating oxygen metabolism may constitute a novel approach to treat viral infections as an adjuvant therapy. The major transcription factor which regulates oxygen tension level is hypoxia-inducible factor-1 alpha (HIF-1α). Down-regulating the expression of HIF-1α is a possible method in the treatment of chronic viral infection such as human immunodeficiency virus infection, chronic hepatitis B and C viral infections and Kaposi sarcoma in addition to classic chemotherapy. The aim of this review is to supply an updating concerning the influence of oxygen tension level in human viral infections and to evoke possible new therapeutic strategies regarding this environmental condition. - Highlights: • Oxygen tension level regulates viral replication in vitro and possibly in vivo. • Hypoxia-inducible factor 1 (HIF-1α) is the principal factor involved in Oxygen tension level. • HIF-1α upregulates gene expression for example of HIV, JC and Kaposi sarcoma viruses. • In addition to classical chemotherapy inhibition of HIF-1α may constitute a new track to treat human viral infections.

Adult and newborn rat inner retinal oxygenation during carbogen and 100% oxygen breathing. Comparison using magnetic resonance imaging delta Po2 mapping.

Science.gov (United States)

Berkowitz, B A

1996-09-01

To test the hypothesis that breathing carbogen (95% O2-5% CO2) oxygenates the inner retina better than breathing 100% oxygen using an magnetic resonance imaging (MRI) method that noninvasively measures inner retinal oxygenation in normal adult and newborn rats. Urethane-anesthetized adult and newborn (day 18) rats were studied. Sequential images were acquired in room air combined with either 100% oxygen or carbogen breathing. Normalized vitreous signal intensity changes were converted to oxygen tension changes (delta PO2) either on a pixel-by-pixel basis or in specific regions of interest. Systemic levels of hyperoxia during carbogen or 100% oxygen breathing were not significantly different (P > 0.05). In the adult rat, a significant difference (P = 0.017) was found in the preretinal vitreous delta PO2 during the breathing of either carbogen (130 +/- 9 mm Hg, mean +/- SEM; n = 5) or 100% oxygen (88 +/- 16 mm Hg; n = 5). Agreement was found between the MRI-determined delta PO2 values and literature oxygen microelectrodes data. In the newborn rat, significant differences (P delta PO2 were found during carbogen (164 +/- 23 mm Hg; n = 3) and oxygen breathing (91 +/- 8 mm Hg; n = 3). MRI delta PO2 mapping demonstrated for the first time that in the normal adult and newborn rat eye, carbogen breathing oxygenates the inner retina better than 100% oxygen breathing.

Mars oxygen production system design

Science.gov (United States)

Cotton, Charles E.; Pillow, Linda K.; Perkinson, Robert C.; Brownlie, R. P.; Chwalowski, P.; Carmona, M. F.; Coopersmith, J. P.; Goff, J. C.; Harvey, L. L.; Kovacs, L. A.

1989-01-01

The design and construction phase is summarized of the Mars oxygen demonstration project. The basic hardware required to produce oxygen from simulated Mars atmosphere was assembled and tested. Some design problems still remain with the sample collection and storage system. In addition, design and development of computer compatible data acquisition and control instrumentation is ongoing.

Oxygen therapy for cluster headache

DEFF Research Database (Denmark)

Petersen, Anja S; Barloese, Mads Cj; Lund, Nunu Lt

2017-01-01

-controlled, crossover inpatient study, and 102 CH attacks were treated with 100% oxygen delivered by demand valve oxygen (DVO), O2ptimask or simple mask (15 liters/min) or placebo delivered by DVO for 15 minutes. Primary endpoint: Two-point decrease of pain on a five-point rating scale within 15 minutes. Results Only...

Pilot study of a new device to titrate oxygen flow in hypoxic patients on long-term oxygen therapy.

Science.gov (United States)

Cirio, Serena; Nava, Stefano

2011-04-01

The O(2) Flow Regulator (Dima, Bologna, Italy) is a new automated oxygen regulator that titrates the oxygen flow based on a pulse-oximetry signal to maintain a target S(pO(2)). We tested the device's safety and efficacy. We enrolled 18 subjects with chronic lung disease, exercise-induced desaturation, and on long-term oxygen therapy, in a randomized crossover study with 2 constant-work-load 15-min cycling exercise tests, starting with the patient's previously prescribed usual oxygen flow. In one test the oxygen flow was titrated manually by the respiratory therapist, and in the other test the oxygen flow was titrated by the O(2) Flow Regulator, to maintain an S(pO(2)) of 94%. We measured S(pO(2)) throughout each test, the time spent by the respiratory therapist to set the device or to manually regulate the oxygen flow, and the total number of respiratory-therapist titration interventions during the trial. There were no differences in symptoms or heart rate between the exercise tests. Compared to the respiratory-therapist-controlled tests, during the O(2) Flow Regulator tests S(pO(2)) was significantly higher (95 ± 2% vs 93 ± 3%, P = .04), significantly less time was spent below the target S(pO(2)) (171 ± 187 s vs 340 ± 220 s, P less respiratory therapist time (5.6 ± 3.7 min vs 2.0 ± 0.1 min, P = .005). The O(2) Flow Regulator may be a safe and effective alternative to manual oxygen titration during exercise in hypoxic patients. It provided stable S(pO(2)) and avoided desaturations in our subjects.

Biogeochemical Modeling of the Second Rise of Oxygen

Science.gov (United States)

Smith, M. L.; Catling, D.; Claire, M.; Zahnle, K.

2014-03-01

The rise of atmospheric oxygen set the tempo for the evolution of complex life on Earth. Oxygen levels are thought to have increased in two broad steps: one step occurred in the Archean ~ 2.45 Ga (the Great Oxidation Event or GOE), and another step occured in the Neoproterozoic ~750-580 Ma (the Neoprotoerozoic Oxygenation Event or NOE). During the NOE, oxygen levels increased from ~1-10% of the present atmospheric level (PAL) (Holland, 2006), to ~15% PAL in the late Neoproterozoic, to ~100% PAL later in the Phanerozoic. Complex life requires O2, so this transition allowed complex life to evolve. We seek to understand what caused the NOE. To explore causes for the NOE, we build upon the biogeochemical model of Claire et al. (2006), which calculates the redox evolution of the atmosphere, ocean, biosphere, and crust in the Archean through to the early Proterozoic. In this model, the balance between oxygenconsuming and oyxgen-producing fluxes evolves over time such that at ~2.4 Ga, the rapidly acting sources of oxygen outweigh the rapidly-acting sinks. Or, in other words, at ~2.4 Ga, the flux of oxygen from organic carbon burial exceeds the sinks of oxygen from reaction with reduced volcanic and metamoprphic gases. The model is able to drive oxygen levels to 1-10% PAL in the Proterozoic; however, the evolving redox fluxes in the model cannot explain how oxygen levels pushed above 1-10% in the late Proterozoic. The authors suggest that perhaps another buffer, such as sulfur, is needed to describe Proterozoic and Phanerozoic redox evolution. Geologic proxies show that in the Proterozoic, up to 10% of the deep ocean may have been sulfidic. With this ocean chemistry, the global sulfur cycle would have worked differently than it does today. Because the sulfur and oxygen cycles interact, the oxygen concentration could have permanently changed due to an evolving sulfur cycle (in combination with evolving redox fluxes associated with other parts of the oxygen cycle and carbon

Algorithmes de reconstruction pour le filtrage en ligne et application à la mesure de la section efficace de la collision $e^{+}e^{-} \\to (e^{+}e^{-})\\eta$ c avec le système de digitalisation rapide pour la chambre à vertex de l'expérience L3

CERN Document Server

Forconi, G

1993-01-01

Algorithmes de reconstruction pour le filtrage en ligne et application à la mesure de la section efficace de la collision $e^{+}e^{-} \\to (e^{+}e^{-})\\eta$ c avec le système de digitalisation rapide pour la chambre à vertex de l'expérience L3

Glow discharge in singlet oxygen

International Nuclear Information System (INIS)

Vagin, N.P.; Ionin, A.A.; Klimachev, Yu.M.; Sinitsyn, D.V.; Yuryshev, N.N.; Kochetov, I.V.; Napartovich, A.P.

2003-01-01

Currently, there is no experimental data on the plasma balance in gas mixtures with a high content of singlet delta oxygen O 2 ( 1 Δ g ). These data can be obtained by studying the parameters of an electric discharge in singlet oxygen produced by a chemical generator. The O 2 ( 1 Δ g ) molecules significantly change the kinetics of electrons and negative ions in plasma. Hence, the discharge conditions at low and high O 2 ( 1 Δ g ) concentrations are very different. Here, the parameters of the positive column of a glow discharge in a gas flow from a chemical singlet-oxygen generator are studied. It is experimentally shown that, at an O 2 ( 1 Δ g ) concentration of 50% and at pressures of 1.5 and 2 torr, the electric field required to sustain the discharge is considerably lower than in the case when all of the oxygen molecules are in the ground state. A theoretical model of the glow discharge is proposed whose predictions are in good agreement with the experimental data

Next Generation Life Support (NGLS): Variable Oxygen Regulator

Data.gov (United States)

National Aeronautics and Space Administration — The objective of the Variable Oxygen Regulator Element is to develop an oxygen-rated, contaminant-tolerant oxygen regulator to control suit pressure with a...

A Low-Power Medical Oxygen Generator, Phase II

Data.gov (United States)

National Aeronautics and Space Administration — An on-board oxygen concentrator is required during long duration manned space missions to supply medical oxygen. The commercial medical oxygen generators based on...

A Low-Power Medical Oxygen Generator, Phase I

Data.gov (United States)

National Aeronautics and Space Administration — An on-board oxygen concentrator is required during long duration manned space missions to supply medical oxygen. The commercial medical oxygen generators based on...

Sources and Contributions of Oxygen During Microbial Pyrite Oxidation: the Triple Oxygen Isotopes of Sulfate

Science.gov (United States)

Ziegler, K.; Coleman, M. L.; Mielke, R. E.; Young, E. D.

2008-12-01

The triple isotopes of oxygen (Δ17O' = δ17O'-0.528 × δ18O' using logarithmic deltas) can trace the oxygen sources of sulfate produced during sulfide oxidation, an important biogeochemical process on Earth's surface and possibly also on Mars [1]. δ18OSO4 compositions are determined by the isotopic selectivity of the mechanism(s) responsible for their changes, and the δ18O value of the reactants (O2 vs. H2O). The relative proportional importance and contribution of each of those sources and mechanisms, as well as their associated isotopic fractionations, are not well understood. We are investigating the use of Δ 17O as a quantitative and qualitative tracer for the different processes and oxygen sources involved in sulfate production. Δ17O signatures are distinct fingerprints of these reservoirs, independent of fractionation factors that can be ambiguous. We conducted controlled abiotic and biotic (Acidithiobacillus ferrooxidans, A.f.) laboratory experiments in which water was spiked with 18O, allowing us to quantify the sources of sulfate oxygen and therefore the processes attending sulfate formation. Results of this Δ17O tracer study show that A.f. microbes initiate pyrite S-oxidation within hours of exposure, and that sulfate is produced from ~90% atmospheric oxygen. This initial lag-phase (behavior in the initial lag-phase will aid in the understanding of the ecological conditions required for microbial populations to establish and survive. An exponential phase of growth, facilitated by microbial Fe2+-oxidation, follows. The source of sulfate rapidly switches to abiotic sulfide oxidation during exponential growth and the source of oxygen switches from atmospheric O2 to nearly ~100% water. Pending acquisition of complimentary chemistry data (in progress), we interpret our isotope data to indicate that the biotic fractionation factor ɛ18OSO4-O2 of at least ~ -25 to - 35‰ is augmented by microbially induced kinetic fractionation; it is larger than

Oxygen diffusion in cuprate superconductors

Energy Technology Data Exchange (ETDEWEB)

Routbort, J.L.; Rothman, S.J.

1995-01-01

Superconducting properties of the cuprate superconductors depend on the oxygen content of the material; the diffusion of oxygen is thus an important process in the fabrication and application of these materials. This article reviews studies of the diffusion of oxygen in La{sub 2}{sub {minus}}{sub {times}}Sr{sub {times}}CuO{sub 4}, YBa{sub 2}Cu{sub 3}O{sub 7}{sub {minus}}{delta}, YBa{sub 2}Cu{sub 4}O{sub 8}, and the Bi{sub 2}Sr{sub 2}Ca{sub n}{sub {minus}}{sub 1}Cu{sub n}O{sub 2}{sub +}{sub 4} (n = 1, and 2) superconductors, and attempt to elucidate the atomic mechanisms responsible.

In-Situ Resource Utilization: Oxygen Production

Data.gov (United States)

National Aeronautics and Space Administration — The leading option for extracting oxygen from the Mars atmospheric carbon dioxide is to use a solid oxide electrolyzer, which removes one oxygen atom from the CO2...

Rencontre avec la civilisation française: l’ambassade de Mehmed Efendi

Directory of Open Access Journals (Sweden)

Marie-Monique Bernard

2011-11-01

Full Text Available Resumo: A embaixada de Mehmed Efendi se apresenta como a oportunidade, para a “Sublime Porte”, para renovar as relações diplomáticas com a França, adormecidas há mais de um século. O embaixador chega a Toulon no dia 22 de novembro de 1720, segue para Paris passando por Bordeaux e pelo vale do Loire; permanecendo em Paris de 16 de março a 3 de agosto de 1721; em seguida desce para Sète, passando por Lyon. A Relação na primeira pessoa refere-se principalmente ao visual, já que a comunicação lingüística era das mais limitadas. Ela retém essencialmente realizações concretas, científicas e técnicas que suscitam a admiração: os cenários da ópera, os instrumentos de astronomia, o canal do Midi, ou a “máquina de Marly”... Tantas “maravilhas” contribuirão para a introdução da influência francesa em Constantinopla.Palavras-chave: História; França; Turquia; Mehmed Efendi.Résumé: L’ambassade de Mehmed Efendi est l’occasion, pour la Sublime Porte, de renouer, avec la France, des relations diplomatiques en sommeil depuis plus d’un siècle. L’ambassadeur arrive à Toulon le 22 novembre 1720; il gagne Paris par Bordeaux et la vallée de la Loire; il y séjourne du 16 mars au 3 août 1721; puis regagne Sète par Lyon. La Relation à la premiére personne se réfère principalment au visuel, la communication linguistique étant des plus limitées. Elle retie essentiellement des réalisations concrètes, scientifiques et techniques qui suscitent l’admiration: les décors de l’opéra, les instruments d’astronomie, le canal du Midi, ou encore la “machine de Marly”... Tant de “merveilles” contribueront à introduire l’influence française à Constantinople.Mots-clés: Histoire; France; Turquie; Mehmed Efendi.Keywords: History; France; Turkey; Mehmed Efendi.

Ekstrakorporal oxygenering ved legionellapneumoni

DEFF Research Database (Denmark)

Uslu, Bülent; Steensen, Morten

2009-01-01

We present a case report with a 49-year-old woman with legionella pneumonia and fulminant respiratory failure. Despite maximal conventional respirator treatment with positive pressure ventilation, 100% oxygen and pharmacological treatment in an intensive care unit, further deterioration with hypo......We present a case report with a 49-year-old woman with legionella pneumonia and fulminant respiratory failure. Despite maximal conventional respirator treatment with positive pressure ventilation, 100% oxygen and pharmacological treatment in an intensive care unit, further deterioration...

Modulation of oxygen-dependent and oxygen-independent metabolism of neutrophilic granulocytes by quantum points.

Science.gov (United States)

Pleskova, S N; Mikheeva, E R

2011-08-01

Inhibition of neutrophilic granulocyte metabolism under the effect of semiconductor quantum points was demonstrated. The status of the oxidative system was evaluated by the NBT test, nonoxidative status by the lysosomal cationic test. It was found that quantum points in a dose of 0.1 mg/ml irrespective of their core and composition of coating significantly inhibited oxygen-dependent and oxygen-independent metabolism of neutrophilic granulocytes.

Oxygen isotope exchange on palladium catalysts

International Nuclear Information System (INIS)

Kravchuk, L.S.; Beschetvertnaya, T.I.; Novorodskij, V.G.; Novikova, M.G.; Zaretskij, M.V.; Valieva, S.V.

1983-01-01

Oxygen heteromolecular isotope exchange on unreduced palladium catalysts, distingushing by metal content is studied. Content of 18 O in gaseous phase is eoual to 46%. Calculations of heteroexchange rates are conducted with decrease of the 18 O in the gaseous phase over solid sample. Method of oxygen thermodesorption has been used to establish that palladium, deposited on γ-Al 2 O 3 during exchange process is in oxidized state; in this case strength of Pd-O bond is determined by content dispersity) of the metal. It is shown that significant increase of exchange rate on the samples with Pd >> 0.5 mass.% content can be induced as by side decomposition reaction of its oxide and corresponding dilution of gaseous mixture by ''light'' oxygen so by possibility of exchange with oxygen of PdO phase

Semiconductors and semimetals oxygen in silicon

CERN Document Server

Willardson, Robert K; Beer, Albert C; Shimura, Fumio

1994-01-01

This volume reviews the latest understanding of the behavior and roles of oxygen in silicon, which will carry the field into the ULSI era from the experimental and theoretical points of view. The fourteen chapters, written by recognized authorities representing industrial and academic institutions, cover thoroughly the oxygen related phenomena from the crystal growth to device fabrication processes, as well as indispensable diagnostic techniques for oxygen.Key Features* Comprehensive study of the behavior of oxygen in silicon* Discusses silicon crystals for VLSI and ULSI applications* Thorough coverage from crystal growth to device fabrication* Edited by technical experts in the field* Written by recognized authorities from industrial and academic institutions* Useful to graduate students, scientists in other disciplines, and active participants in the arena of silicon-based microelectronics research* 297 original line drawings

Insulin resistance and maximal oxygen uptake

DEFF Research Database (Denmark)

Seibaek, Marie; Vestergaard, Henrik; Burchardt, Hans

2003-01-01

BACKGROUND: Type 2 diabetes, coronary atherosclerosis, and physical fitness all correlate with insulin resistance, but the relative importance of each component is unknown. HYPOTHESIS: This study was undertaken to determine the relationship between insulin resistance, maximal oxygen uptake......, and the presence of either diabetes or ischemic heart disease. METHODS: The study population comprised 33 patients with and without diabetes and ischemic heart disease. Insulin resistance was measured by a hyperinsulinemic euglycemic clamp; maximal oxygen uptake was measured during a bicycle exercise test. RESULTS......: There was a strong correlation between maximal oxygen uptake and insulin-stimulated glucose uptake (r = 0.7, p = 0.001), and maximal oxygen uptake was the only factor of importance for determining insulin sensitivity in a model, which also included the presence of diabetes and ischemic heart disease. CONCLUSION...

Oxygen supplementation for critically ill patients

DEFF Research Database (Denmark)

Barbateskovic, M; Schjørring, O L; Jakobsen, J C

2018-01-01

. The objective of this systematic review is to critically assess the evidence of randomised clinical trials on the effects of higher versus lower inspiratory oxygen fractions or targets of arterial oxygenation in critically ill adult patients. METHODS: We will search for randomised clinical trials in major......BACKGROUND: In critically ill patients, hypoxaemia is a common clinical manifestation of inadequate gas exchange in the lungs. Supplemental oxygen is therefore given to all critically ill patients. This can result in hyperoxaemia, and some observational studies have identified harms with hyperoxia...... in international guidelines despite lack of robust evidence of its effectiveness. To our knowledge, no systematic review of randomised clinical trials has investigated the effects of oxygen supplementation in critically ill patients. This systematic review will provide reliable evidence to better inform future...

TURBULENT OXYGEN FLAMES IN TYPE Ia SUPERNOVAE

International Nuclear Information System (INIS)

Aspden, A. J.; Bell, J. B.; Woosley, S. E.

2011-01-01

In previous studies, we examined turbulence-flame interactions in carbon-burning thermonuclear flames in Type Ia supernovae. In this study, we consider turbulence-flame interactions in the trailing oxygen flames. The two aims of the paper are to examine the response of the inductive oxygen flame to intense levels of turbulence, and to explore the possibility of transition to detonation in the oxygen flame. Scaling arguments analogous to the carbon flames are presented and then compared against three-dimensional simulations for a range of Damkoehler numbers (Da 16 ) at a fixed Karlovitz number. The simulations suggest that turbulence does not significantly affect the oxygen flame when Da 16 16 >1, turbulence enhances heat transfer and drives the propagation of a flame that is narrower than the corresponding inductive flame would be. Furthermore, burning under these conditions appears to occur as part of a combined carbon-oxygen turbulent flame with complex compound structure. The simulations do not appear to support the possibility of a transition to detonation in the oxygen flame, but do not preclude it either.

Vivre avec ou par le risque à l’île de Sein ?

Directory of Open Access Journals (Sweden)

Annaig Oiry

2012-02-01

Full Text Available L’île de Sein, située au large des côtes finistériennes, fait figure de « territoire du risque » par excellence : cette île basse est confrontée à de fréquentes et violentes tempêtes, la population vit « avec le risque » de submersion depuis des générations tout en voyant la probabilité des aléas catastrophiques augmenter en raison de la carence en aménagement et des conséquences probables du réchauffement climatique. L’image du risque, notamment les photographies de tempête, sert de support à la diffusion d’un sentiment anxiogène justifiant des actions de gestion du risque, mais entretient aussi un sentiment de fascination à l’égard des épisodes tempétueux. Cependant, les îliens portent un regard bien plus critique sur le spectaculaire véhiculé par de telles représentations. Le présent article se penche sur ces rapports entre représentations sociales du risque et iconographie du risque.This article stresses on relationships between hazard’s social representations and iconographies. As an illustration, Sein Island (located near by the Brittany coast, in Finistère. This island is considered as a symbol of natural hazard territory: indeed this low island has been confronted for decades to face significant flood hazard that is nowadays strengthened by the consequences of global warming and a lack of infrastructures. Pictures of flood hazards, and more particularly pictures of storms, are used in order to spread around the fear of natural disasters. This fear justifies the management policies implemented on the island. However islanders criticize pictures which are too spectacular and too distorted. Those gaps between hazard’s representations and iconographies are the main subjects of this article.

Beyond the top of the volcano? A unified approach to electrocatalytic oxygen reduction and oxygen evolution

Czech Academy of Sciences Publication Activity Database

Busch, M.; Halck, N. B.; Kramm, U. I.; Siehrostami, S.; Krtil, Petr; Rossmeisl, J.

2016-01-01

Roč. 29, NOV 2016 (2016), s. 126-135 ISSN 2211-2855 Institutional support: RVO:61388955 Keywords : hydrogen evolution * catalytic-activity * Electrocatalysis * Oxygen reduction * Oxygen evolution * Volcano * Density functional theory Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 12.343, year: 2016

Aquatic respiration rate measurements at low oxygen concentrations.

Directory of Open Access Journals (Sweden)

Moritz Holtappels

Full Text Available Despite its huge ecological importance, microbial oxygen respiration in pelagic waters is little studied, primarily due to methodological difficulties. Respiration measurements are challenging because of the required high resolution of oxygen concentration measurements. Recent improvements in oxygen sensing techniques bear great potential to overcome these limitations. Here we compare 3 different methods to measure oxygen consumption rates at low oxygen concentrations, utilizing amperometric Clark type sensors (STOX, optical sensors (optodes, and mass spectrometry in combination with (18-18O2 labeling. Oxygen concentrations and consumption rates agreed well between the different methods when applied in the same experimental setting. Oxygen consumption rates between 30 and 400 nmol L(-1 h(-1 were measured with high precision and relative standard errors of less than 3%. Rate detection limits in the range of 1 nmol L(-1 h(-1 were suitable for rate determinations in open ocean water and were lowest at the lowest applied O2 concentration.

Effect of oxygen breathing on micro oxygen bubbles in nitrogen-depleted rat adipose tissue at sea level and 25 kPa altitude exposures

DEFF Research Database (Denmark)

Randsoe, Thomas; Hyldegaard, Ole

2012-01-01

The standard treatment of altitude decompression sickness (aDCS) caused by nitrogen bubble formation is oxygen breathing and recompression. However, micro air bubbles (containing 79% nitrogen), injected into adipose tissue, grow and stabilize at 25 kPa regardless of continued oxygen breathing...... at 101.3 kPa (sea level) or at 25 kPa altitude exposures during continued oxygen breathing. In keeping with previous observations and bubble kinetic models, we hypothesize that oxygen breathing may contribute to oxygen bubble growth at altitude. Anesthetized rats were exposed to 3 h of oxygen...... prebreathing at 101.3 kPa (sea level). Micro oxygen bubbles of 500-800 nl were then injected into the exposed abdominal adipose tissue. The oxygen bubbles were studied for up to 3.5 h during continued oxygen breathing at either 101.3 or 25 kPa ambient pressures. At 101.3 kPa, all bubbles shrank consistently...

Oxygen sensitization of mammalian cells under different irradiation conditions

International Nuclear Information System (INIS)

Ling, C.C.; Michaels, H.B.; Gerweck, L.E.; Epp, E.R.; Peterson, E.C.

1981-01-01

The oxygen dependence of the radiosensitivity of cultured CHO cells was examined in detail with particular attention paid to avoiding possible artifacts due to radiolytic oxygen depletion. Two methods of gas equilibration and irradiation were used. In the first approach, cells were irradiated with 50-kVp X rays in a thin-layer geometry which offered maximum interchange between the cells and the surrounding gas. The second technique employed 280-kVp X irradiation of cells under full-medium conditions with mechanical agitation to minimize the effect of radiochemical oxygen consumption by promoting rapid oxygen replenishment. With these techniques oxygen radiosensitization was clearly resolved at an oxygen concentration of 0.03% in the gas phase. The oxygen K curves measured by these two methods were similar in shape over a wide range of oxygen concentration

The formation of non-oxidic oxygen phases on Ru(0001). From the first stages of the oxygen take-up to oxidation

International Nuclear Information System (INIS)

Blume, R.

2005-01-01

The aim of the thesis presented here was the investigation of the formation of non oxidic oxygen phases on the Ru(0001) surface. Smooth and defect rich surfaces were exposed to high oxygen pressures (up to 1 bar) at moderate temperatures (550 K). The characterisation was performed under UHV conditions using Thermal Desorption Spectroscopy (TDS), Scanning Photoemission Microscopy (SPEM), Thermal Energy Atomic Scattering (TEAS), Ultraviolett Photoelectron Spectroscopy (UPS) and Low Energy Electron Diff raction (LEED) as well as In situ by the In Situ X-Ray Photoelectron Spectroscopy (In Situ XPS). The application of this Low Temperature preparation procedure (LT) leads to an Oxygen uptake up to 3 MLE of ''subsurface'' oxygen into a smooth Ru(0001) surface without the typical indications of oxidation (MLE: Monolayer Equivalent). The accumulation of oxygen beneath the surface starts immediatly after the completion of a full chemisorbed layer. Here, the local saturation of the adsorbed oxygen is the decisive step. Diff usion of oxygen directly through the chemisorbed layer only slightly contributes to the overall uptake. Oxygen is mostly accomodated in the vicinity of the surface via surface defects which has been shown on defect rich surfaces created by mild Ar+ sputtering. The maximum oxygen capacity is 10 Atoms/Defect. The uptake is thermally activated with an activation energy of 0.15 eV. The oxygen uptake causes a massive structural change of at least the top two ruthenium layers. Whereas the ruthenium atoms of the first layer are coordinated with up to four, those of the second layer are coordinated with up to two oxygen atoms. These binding condition are metastable and can be changed by annealing the surface. With reaching the desorption temperature two distinct desorption peaks are observed with TDS. For an accumulation of about 0.5 MLE of ''subsurface'' oxygen the desorption proceeds exclusively at the characteristic temperature of the chemisorbed layer at 1040

Development of oxygen sensing technology in an irradiated fuel rod. Characteristic test of oxygen sensor

International Nuclear Information System (INIS)

Saito, Junichi; Hoshiya, Taiji; Sakurai, Fumio; Sakai, Haruyuki

1996-03-01

At the Department of JMTR (Japan Materials Test Reactor), the re-instrumentation technologies to a high burnup fuel rod irradiated in an LWR have been developed to study irradiation behavior of the fuel during power transient. It has been progressed developing a chemical sensor as one of the re-instrumentation technologies. This report summarizes the results of characteristic tests of an oxygen sensor made of Yttria Stabilized Zirconia (YSZ) as a solid electrolyte. Several kinds of experiments were carried out to evaluate the electromotive force (emf) performance, stability and lifetime of the oxygen sensor with Ni/NiO, Cr/Cr 2 O 3 and Fe/FeO, respectively as a reference electrode. From the experimental data, it is suggested that the reference electrode of Ni/NiO reveals the most appropriate characteristic of the sensor to measure the partial oxygen pressure in a fuel rod. It is the final goal of this development to clarify the change of oxygen chemical potential in a fuel rod during power transient. (author)

Oxygen - A Four Billion Year History

DEFF Research Database (Denmark)

Canfield, Donald Eugene

of fields, including geology, paleontology, geochemistry, biochemistry, animal physiology, and microbiology, to explain why our oxygenated Earth became the ideal place for life. Describing which processes, both biological and geological, act to control oxygen levels in the atmosphere, Canfield traces...... guides readers through the various lines of scientific evidence, considers some of the wrong turns and dead ends along the way, and highlights the scientists and researchers who have made key discoveries in the field. Showing how Earth's atmosphere developed over time, Oxygen takes readers...

Oxygen enriched combustion system performance study. Phase 2: 100 percent oxygen enriched combustion in regenerative glass melters, Final report

Energy Technology Data Exchange (ETDEWEB)

Tuson, G.B.; Kobayashi, H.; Campbell, M.J.

1994-08-01

The field test project described in this report was conducted to evaluate the energy and environmental performance of 100% oxygen enriched combustion (100% OEC) in regenerative glass melters. Additional objectives were to determine other impacts of 100% OEC on melter operation and glass quality, and to verify on a commercial scale that an on-site Pressure Swing Adsorption oxygen plant can reliably supply oxygen for glass melting with low electrical power consumption. The tests constituted Phase 2 of a cooperative project between the United States Department of Energy, and Praxair, Inc. Phase 1 of the project involved market and technical feasibility assessments of oxygen enriched combustion for a range of high temperature industrial heating applications. An assessment of oxygen supply options for these applications was also performed during Phase 1, which included performance evaluation of a pilot scale 1 ton per day PSA oxygen plant. Two regenerative container glass melters were converted to 100% OEC operation and served as host sites for Phase 2. A 75 ton per day end-fired melter at Carr-Lowrey Glass Company in Baltimore, Maryland, was temporarily converted to 100% OEC in mid- 1990. A 350 tpd cross-fired melter at Gallo Glass Company in Modesto, California was rebuilt for permanent commercial operation with 100% OEC in mid-1991. Initially, both of these melters were supplied with oxygen from liquid storage. Subsequently, in late 1992, a Pressure Swing Adsorption oxygen plant was installed at Gallo to supply oxygen for 100% OEC glass melting. The particular PSA plant design used at Gallo achieves maximum efficiency by cycling the adsorbent beds between pressurized and evacuated states, and is therefore referred to as a Vacuum/Pressure Swing Adsorption (VPSA) plant.

Characterization of carbonaceous solids by oxygen chemisorption

Energy Technology Data Exchange (ETDEWEB)

Furimsky, E.; Palmer, A.; Duguay, D.G.; McConnell, D.G.; Henson, D.E.

1988-06-01

Oxygen chemisorption of high and low carbon carbonaceous solids was measured in an electro-microbalance at 200 degrees C in air. A linear correlation between the amount of chemisorbed oxygen and H/C ratio as well as aromaticity was established for the high carbon solids. For the low carbon solids a linear correlation was established between the amount of chemisorbed oxygen and the content of organic matter. Experimental observations are discussed in terms of structural aspects of the solids. Oxygen chemisorption is a suitable technique for a rapid characterization of carbonaceous solids including coal. 15 refs., 7 figs., 3 tabs.

Pharmaceutical preparation of oxygen-15 labelled molecular oxygen and carbon monoxide gasses in a hospital setting.

NARCIS (Netherlands)

Luurtsema, Geert; Boellaard, Ronald; Greuter, Henri; Rijbroek, Abraham; Takkenkamp, Kevin; de Geest, Frank; Buijs, Fred; Hendrikse, NH; Franssen, Eric; van Lingen, Arthur; Lammertsma, Adriaan A.

BACKGROUND: Clinical positron emission tomography (PET) requires safe and effective PET radiopharmaceuticals. Tracers used for measuring oxygen consumption and blood volume are [(15)O]O(2) and [(15)O]CO, respectively. In general, these oxygen-15 labelled tracers are produced using a cyclotron that

Radiosensitizers and the oxygen effects in mammalian cells

International Nuclear Information System (INIS)

Millar, B.C.; Fielden, E.M.; Steele, J.J.

1979-01-01

The survival curves for Chinese Hamster cells irradiated under various oxygen tensions have been determined. The variation in OER with oxygen concentration shows two distinct components. Between 1.4 and 7.0 μM the OER is constant with a value of 1.9. Experiments with nitroaromatic radiosensitizers in combination with low concentrations of oxygen show that they can all mimic the 'low concentration' oxygen effect. Of the compounds tested only misonidazole can apparently mimic the 'high concentration' oxygen effect although the full OER cannot be obtained with the authors cell line because of toxicity by the sensitizer. (Auth.)

A fortran program for elastic scattering of deuterons with an optical model containing tensorial potentials; Programme fortran pour la diffusion elastique de deutons avec un modele optique contenant des termes tensoriels

Energy Technology Data Exchange (ETDEWEB)

Raynal, J [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1963-07-01

The optical model has been applied with success to the elastic scattering of particles of spin 0 and 1/2 and to a lesser degree to that of deuterons. For particles of spin l/2, an LS coupling term is ordinarily used; this term is necessary to obtain a polarization; for deuterons, this coupling has been already introduced, but the possible forms of potentials are more numerous (in this case, scalar products of a second rank spin tensor with a tensor of the same rank in space or momentum can occur). These terms which may be necessary are primarily important for the tensor polarization. This problem is of particular interest at Saclay since a beam of polarized deuterons has become available. The FORTRAN program SPM 037 permits the study of the effect of tensorial potentials constructed from the distance of the deuteron from the target and its angular momentum with respect to it. This report should make possible the use and even the modification of the program. It consists of: a description of the problem and of the notation employed, a presentation of the methods adopted, an indication of the necessary data and how they should be introduced, and finally tables of symbols which are in equivalence or common statements: these tables must be considered when making any modification. (author) [French] Le modele optique a ete applique avec succes a la diffusion elastique des particules de spin nul et 1/2 et dans une moindre mesure a celle des deutons. Pour les particules de spin 1/2, on utilise habituellement un couplage LS, necessaire pour calculer la polarisation; pour les deutons, ce couplage a deja ete introduit, mais les formes de potentiel possibles sont plus nombreuses (intervention de produits scalaires d'un tenseur d'ordre 2 de spin avec un tenseur du meme ordre d'espace ou d'impulsion) et celles qui peuvent etre eventuellement necessaires ont une importance capitale pour la polarisation tensorielle. Ce probleme revet a Saclay un interet particulier depuis la mise

A fortran program for elastic scattering of deuterons with an optical model containing tensorial potentials; Programme fortran pour la diffusion elastique de deutons avec un modele optique contenant des termes tensoriels

Energy Technology Data Exchange (ETDEWEB)

Raynal, J. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1963-07-01

The optical model has been applied with success to the elastic scattering of particles of spin 0 and 1/2 and to a lesser degree to that of deuterons. For particles of spin l/2, an LS coupling term is ordinarily used; this term is necessary to obtain a polarization; for deuterons, this coupling has been already introduced, but the possible forms of potentials are more numerous (in this case, scalar products of a second rank spin tensor with a tensor of the same rank in space or momentum can occur). These terms which may be necessary are primarily important for the tensor polarization. This problem is of particular interest at Saclay since a beam of polarized deuterons has become available. The FORTRAN program SPM 037 permits the study of the effect of tensorial potentials constructed from the distance of the deuteron from the target and its angular momentum with respect to it. This report should make possible the use and even the modification of the program. It consists of: a description of the problem and of the notation employed, a presentation of the methods adopted, an indication of the necessary data and how they should be introduced, and finally tables of symbols which are in equivalence or common statements: these tables must be considered when making any modification. (author) [French] Le modele optique a ete applique avec succes a la diffusion elastique des particules de spin nul et 1/2 et dans une moindre mesure a celle des deutons. Pour les particules de spin 1/2, on utilise habituellement un couplage LS, necessaire pour calculer la polarisation; pour les deutons, ce couplage a deja ete introduit, mais les formes de potentiel possibles sont plus nombreuses (intervention de produits scalaires d'un tenseur d'ordre 2 de spin avec un tenseur du meme ordre d'espace ou d'impulsion) et celles qui peuvent etre eventuellement necessaires ont une importance capitale pour la polarisation tensorielle. Ce probleme revet a Saclay un interet

Ceria Based Composite Membranes for Oxygen Separation

DEFF Research Database (Denmark)

Gurauskis, Jonas; Ovtar, Simona; Kaiser, Andreas

2014-01-01

Mixed ionic-electronic conducting membranes for oxygen gas separation are attracting a lot of interest due to their promising potential for the pure oxygen and the syngas production. Apart from the need for a sufficiently high oxygen permeation fluxes, the prolonged stability of these membranes...... under the large oxygen potential gradients at elevated temperatures is decisive for the future applications. The gadolinium doped cerium oxide (CGO) based composite membranes are considered as promising candidates due to inherent stability of CGO phase. The CGO matrix is a main oxygen ion transporter......; meanwhile the primary role of a secondary phase in this membrane is to compensate the low electronic conductivity of matrix at intended functioning conditions. In this work thin film (15-20 μm) composite membranes based on CGO matrix and LSF electronic conducting phase were fabricated and evaluated...

Asthma and hemoglobinopathy: when is supplemental oxygen required?

Science.gov (United States)

Joseph, Leon; Brickner-Braun, Inbal; Pinshow, Berry; Goldberg, Shmuel; Miskin, Hagit; Picard, Elie

2013-10-01

Asthma is the most common reason for referral to the emergency department in childhood. In severe attacks, supplemental O2 is given when oxygen saturation level is asthma attack. Simultaneously, P(a)O2 was normal. A diagnosis of abnormal hemoglobin with decreased oxygen affinity (hemoglobin Seattle) was made on hemoglobin electrophoresis and genetic analysis. To ascertain when supplemental oxygen was needed, an oxygen dissociation curve was plotted using the tonometer technique, and it was found that an S(p)O2 of 70% is parallel to a P(a)O2 of 60 mmHg. Plotting an oxygen dissociation curve is a simple reproducible method to determine when supplemental oxygen is required for a child with a hemoglobinopathy. © 2013 The Authors. Pediatrics International © 2013 Japan Pediatric Society.

Measurement of oxygen transfer from air into organic solvents

DEFF Research Database (Denmark)

Ramesh, Hemalata; Mayr, Torsten; Hobisch, Mathias

2016-01-01

biological reactions require the supply of oxygen, most normally from air. However, reliable on-line measurements of oxygen concentration in organic solvents (and hence oxygen transfer rates from air to the solvent) has to date proven impossible due limitations in the current analytical methods. Results...... applications). Subsequently, we measured the oxygen transfer rates from air into these organic solvents. Conclusion The measurement of oxygen transfer rates from air into organic solvents using the dynamic method was established using the solvent resistant optical sensor. The feasibility of online oxygen...... For the first time, we demonstrate on-line oxygen measurements in non-aqueous media using a novel optical sensor. The sensor was used to measure oxygen concentration in various organic solvents including toluene, THF, isooctane, DMF, heptane and hexane (which have all been shown suitable for several biological...

Sorbent-based Oxygen Production for Energy Systems

Energy Technology Data Exchange (ETDEWEB)

Sethi, Vijay [Western Research Inst. (WRI), Laramie, WY (United States)

2017-01-31

Project DE-FE0024075 deals with the development of a moderate-temperature sorbent-based oxygen production technology. Sorbent-based oxygen production process utilizes oxygen-storage properties of Perovskites to (1) adsorb oxygen from air in a solid sorbent, and (2) release the adsorbed oxygen into a sweep gas such as CO₂ and/or steam for gasification systems or recycled flue gas for oxy-combustion systems. Pure oxygen can be produced by the use of vacuum instead of a sweep gas to affect the pressure swing. By developing more efficient and stable, higher sorption capacity, newer class of materials operating at moderate temperatures this process represents a major advancement in air separation technology. Newly developed perovskite ceramic sorbent materials with order-disorder transition have a higher O₂ adsorption capacity, potentially 200 °C lower operating temperatures, and up to two orders of magnitude faster desorption rates than those used in earlier development efforts. The performance advancements afforded by the new materials lead to substantial savings in capital investment and operational costs. Cost of producing oxygen using sorbents could be as much as 26% lower than VPSA and about 13% lower than a large cryogenic air separation unit. Cost advantage against large cryogenic separation is limited because sorbent-based separation numbers up sorbent modules for achieving the larger capacity.

Singlet oxygen treatment of tumor cells triggers extracellular singlet oxygen generation, catalase inactivation and reactivation of intercellular apoptosis-inducing signaling☆

Science.gov (United States)

Riethmüller, Michaela; Burger, Nils; Bauer, Georg

2015-01-01

Intracellular singlet oxygen generation in photofrin-loaded cells caused cell death without discrimination between nonmalignant and malignant cells. In contrast, extracellular singlet oxygen generation caused apoptosis induction selectively in tumor cells through singlet oxygen-mediated inactivation of tumor cell protective catalase and subsequent reactivation of intercellular ROS-mediated apoptosis signaling through the HOCl and the NO/peroxynitrite signaling pathway. Singlet oxygen generation by extracellular photofrin alone was, however, not sufficient for optimal direct inactivation of catalase, but needed to trigger the generation of cell-derived extracellular singlet oxygen through the interaction between H2O2 and peroxynitrite. Thereby, formation of peroxynitrous acid, generation of hydroxyl radicals and formation of perhydroxyl radicals (HO2.) through hydroxyl radical/H2O2 interaction seemed to be required as intermediate steps. This amplificatory mechanism led to the formation of singlet oxygen at a sufficiently high concentration for optimal inactivation of membrane-associated catalase. At low initial concentrations of singlet oxygen, an additional amplification step needed to be activated. It depended on singlet oxygen-dependent activation of the FAS receptor and caspase-8, followed by caspase-8-mediated enhancement of NOX activity. The biochemical mechanisms described here might be considered as promising principle for the development of novel approaches in tumor therapy that specifically direct membrane-associated catalase of tumor cells and thus utilize tumor cell-specific apoptosis-inducing ROS signaling. PMID:26225731

Oxygen delivery in irradiated normal tissue

Energy Technology Data Exchange (ETDEWEB)

Kiani, M.F.; Ansari, R. [Univ. of Tennessee Health Science Center, Memphis, TN (United States). School of Biomedical Engineering; Gaber, M.W. [St. Jude Children' s Research Hospital, Memphis, TN (United States)

2003-03-01

Ionizing radiation exposure significantly alters the structure and function of microvascular networks, which regulate delivery of oxygen to tissue. In this study we use a hamster cremaster muscle model to study changes in microvascular network parameters and use a mathematical model to study the effects of these observed structural and microhemodynamic changes in microvascular networks on oxygen delivery to the tissue. Our experimental observations indicate that in microvascular networks while some parameters are significantly affected by irradiation (e.g. red blood cell (RBC) transit time), others remain at the control level (e.g. RBC path length) up to 180 days post-irradiation. The results from our mathematical model indicate that tissue oxygenation patterns are significantly different in irradiated normal tissue as compared to age-matched controls and the differences are apparent as early as 3 days post irradiation. However, oxygen delivery to irradiated tissue was not found to be significantly different from age matched controls at any time between 7 days to 6 months post-irradiation. These findings indicate that microvascular late effects in irradiated normal tissue may be due to factors other than compromised tissue oxygenation. (author)

Interaction of oxygen with zirconia surface

International Nuclear Information System (INIS)

Ivankiv, L.I.; Ketsman, I.V.

1999-01-01

The influence of surface heat treatment, electron (50-800) eV irradiation and UV (180-300) nM illumination of adsorption system on the state of oxygen adsorbed on zirconia surface have been investigated. On the basis of experimental results obtained by investigation of photon emission accompanying oxygen adsorption (AL) and TPD data existence of adsorption sites on the surface is suggested on which irreversible dissociative adsorption of oxygen occurs. These very sites are associated with emission processes Conclusion is made that the only type of adsorption sites connected with anion vacancy is present on zirconia surface and this is its charge state that determines the state of adsorbed oxygen. One of the important mechanisms by which the electron and UV photon excitation affects the adsorption interaction is the change of the charge state of the adsorption site

Optoacoustic measurements of human placenta and umbilical blood oxygenation

Science.gov (United States)

Nanovskaya, T. N.; Petrov, I. Y.; Petrov, Y.; Patrikeeva, S. L.; Ahmed, M. S.; Hankins, G. D. V.; Prough, D. S.; Esenaliev, R. O.

2016-03-01

Adequate oxygenation is essential for normal embryogenesis and fetal growth. Perturbations in the intrauterine oxidative environment during pregnancy are associated with several pathophysiological disorders such as pregnancy loss, preeclampsia, and intrauterine growth restriction. We proposed to use optoacoustic technology for monitoring placental and fetal umbilical blood oxygenation. In this work, we studied optoacoustic monitoring of oxygenation in placenta and umbilical cord blood ex vivo using technique of placenta perfusion. We used a medical grade, nearinfrared, tunable, optoacoustic system developed and built for oxygenation monitoring in blood vessels and in tissues. First, we calibrated the system for cord blood oxygenation measurements by using a CO-Oximeter (gold standard). Then we performed validation in cord blood circulating through the catheters localized on the fetal side of an isolated placental lobule. Finally, the oxygenation measurements were performed in the perfused placental tissue. To increase or decrease blood oxygenation, we used infusion of a gas mixture of 95% O2 + 5% CO2 and 95% N2 + 5% CO2, respectively. In placental tissue, up to four cycles of changes in oxygenation were performed. The optoacoustically measured oxygenation in circulating cord blood and in placental lobule closely correlated with the actual oxygenation data measured by CO-Oximeter. We plan to further test the placental and cord blood oxygenation monitoring with optoacoustics in animal and clinical studies.

Large arteriolar component of oxygen delivery implies a safe margin of oxygen supply to cerebral tissue.

Science.gov (United States)

Sakadžić, Sava; Mandeville, Emiri T; Gagnon, Louis; Musacchia, Joseph J; Yaseen, Mohammad A; Yucel, Meryem A; Lefebvre, Joel; Lesage, Frédéric; Dale, Anders M; Eikermann-Haerter, Katharina; Ayata, Cenk; Srinivasan, Vivek J; Lo, Eng H; Devor, Anna; Boas, David A

2014-12-08

What is the organization of cerebral microvascular oxygenation and morphology that allows adequate tissue oxygenation at different activity levels? We address this question in the mouse cerebral cortex using microscopic imaging of intravascular O2 partial pressure and blood flow combined with numerical modelling. Here we show that parenchymal arterioles are responsible for 50% of the extracted O2 at baseline activity, and the majority of the remaining O2 exchange takes place within the first few capillary branches. Most capillaries release little O2 at baseline acting as an O2 reserve that is recruited during increased neuronal activity or decreased blood flow. Our results challenge the common perception that capillaries are the major site of O2 delivery to cerebral tissue. The understanding of oxygenation distribution along arterio-capillary paths may have profound implications for the interpretation of blood-oxygen-level dependent (BOLD) contrast in functional magnetic resonance imaging and for evaluating microvascular O2 delivery capacity to support cerebral tissue in disease.

Photoacoustic Imaging in Oxygen Detection

Directory of Open Access Journals (Sweden)

Fei Cao

2017-12-01

Full Text Available Oxygen level, including blood oxygen saturation (sO2 and tissue oxygen partial pressure (pO2, are crucial physiological parameters in life science. This paper reviews the importance of these two parameters and the detection methods for them, focusing on the application of photoacoustic imaging in this scenario. sO2 is traditionally detected with optical spectra-based methods, and has recently been proven uniquely efficient by using photoacoustic methods. pO2, on the other hand, is typically detected by PET, MRI, or pure optical approaches, yet with limited spatial resolution, imaging frame rate, or penetration depth. Great potential has also been demonstrated by employing photoacoustic imaging to overcome the existing limitations of the aforementioned techniques.

Changes in Oxygen Partial Pressure in the Vitreous Body and Arterial Blood of Rabbits Depending on Oxygen Concentration in Inspired Mixture.

Science.gov (United States)

Amkhanitskaya, L I; Nikolaeva, G V; Sokolova, N A

2015-07-01

We demonstrated that the vitreous body of one-month-old rabbits becomes a "reservoir" for storage and accumulation of oxygen after exposure to additional oxygenation of the organism (O2 concentrations in inspired gas mixture were 40, 60, 85, and 99%). The higher was O2 concentration in inspired mixture, the higher was oxygen saturation of the blood and vitreous body. O2 concentration of 40% was relatively safe for eye tissues. O2 concentration >60% induced oxygen accumulation in the vitreous body, which can be a provoking factor for the development of oxygen-induced pathologies.

Comparison of the OxyMask and Venturi Mask in the Delivery of Supplemental Oxygen: Pilot Study in Oxygen-Dependent Patients

OpenAIRE

Beecroft, Jaime M; Hanly, Patrick J

2006-01-01

BACKGROUND: The OxyMask (Southmedic Inc, Canada) is a new face mask for oxygen delivery that uses a small ‘diffuser’ to concentrate and direct oxygen toward the mouth and nose. The authors hypothesized that this unique design would enable the OxyMask to deliver oxygen more efficiently than a Venturi mask (Hudson RCI, USA) in patients with chronic hypoxemia.METHODS: Oxygen-dependent patients with chronic, stable respiratory disease were recruited to compare the OxyMask and Venturi mask in a ra...

Kinetics of oxygen exchange between bisulfite ion and water as studied by oxygen-17 nuclear magnetic resonance spectroscopy

International Nuclear Information System (INIS)

Horner, D.A.

1984-08-01

The nuclear magnetic relaxation times of oxygen-17 have been measured in aqueous sodium bisulfite solutions in the pH range from 2.5 to 5 as a function of temperature, pH, and S(IV) concentration, at an ionic strength of 1.0 m. The rate law for oxygen exchange between bisulfite ion and water was obtained from an analysis of the data, and is consistent with oxygen exchange occurring via the reaction SO 2 + H 2 O right reversible H + + SHO 3 - . The value of k/sub -1/ is in agreement with relaxation measurements. Direct spectroscopic evidence was found for the existence of two isomers of bisulfite ion: one with the proton bonded to the sulfur (HSO 3 - ) and the other with the proton bonded to an oxygen (SO 3 H - ). (The symbol SHO 3 - in the above chemical equation refers to both isomeric forms of bisulfite ion.) The relative amounts of the two isomers were determined as a function of temperature, and the rate and mechanism of oxygen exchange between the two was investigated. One of the two isomers, presumably SO 3 H - , exchanges oxygens with water much more rapidly than does the other. A two-pulse sequence was developed which greatly diminished the solvent peak in the NMR spectrum

The experimental study of oxygen contrast MR ventilation imaging

International Nuclear Information System (INIS)

Yang Jian; Guo Youmin; Wu Xiaoming; Xi Nong; Wang Jianguo; Zhu Li; Lei Xiaoyan; Xie Enyi

2003-01-01

Objective: To study the feasibility and basic technology of the oxygen contrast MR ventilation imaging in lung. Methods: Six canine lungs were scanned by using inversion recovery pulse sequence with turbo spin echo acquisition before and after inhalation of the 100% oxygen as T 1 contrast agent, and the T 1 values were measured. The contrast-to-noise ratio (CNR) for each inversion recovery time was compared and the relationship between arterial blood oxygen pressure (PaO 2 ) and T 1 relaxation rate was observed. Subtraction technique was employed in the postprocessing of pre- and post-oxygen conditions. Results: Molecular oxygen could shorten the pulmonary T 1 value (average 13.37%, t=2.683, P 1 value of pre- and post-oxygen conditions. The relaxtivity of T 1 resulted in excellent linear correlation (r 2 =0.9974) with PaO 2 . Through the subtraction of pre- and post-oxygen image, the oxygen contrast MR ventilation -image was obtained. Conclusion: The oxygen contrast MR ventilation imaging has the feasibility and clinical potential for the assessment of regional pulmonary function

Study of the high temperature oxidation of nickel; Contribution a l'etude de l'oxydation du nickel aux temperatures elevees

Energy Technology Data Exchange (ETDEWEB)

Berry, L [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

1967-11-01

The parabolic oxidation of nickel by oxygen and by air at atmospheric pressure has been studied in the temperature range 600 to 1400 C, in particular by thermogravimetric and micrographic techniques. The mechanism of the reaction has been determined; it has been shown in particular that the break in the Arrhenius plot of the kinetics, occurring at about 950 C, is the result of a stimulation of the diffusion across the nickel prot-oxide film above this temperature; this is the result of the presence of excess nickel vacancies in the film. A systematic study has also been made of the influence of the oxygen pressure P{sub O{sub 2}} (10{sup -2} torr {<=} P{sub O{sub 2}} {<=} 760 torr) on the parabolic oxidation of nickel between 800 and 1400 C. In the range 1000 to 1400 C, the activation energy of the process decreases monotonously from 57 to 34 kcal/mole as P{sub O{sub 2}} decreases from 760 to 1 torr. Furthermore, it has been shown that the parabolic oxidation constant is proportional to P{sub O{sub 2}}{sup 1/n} the value of n is not invariant however in the temperature range examined, but decreases from 6 to about 3 when the temperature increases from 900 to 1400 C. Finally, a study has been made of the oxidation of nickel in carbon dioxide at atmospheric pressure between 750 and 1400 C. The main reaction is Ni + CO{sub 2} {yields} NiO + CO, and corresponds, with a good approximation, to the reaction of the metal with the oxygen produced by the thermal dissociation of the CO{sub 2}. (author) [French] L'oxydation parabolique du nickel avec l'oxygene et l'air a la pression atmospherique a ete etudiee dans l'intervalle de temperatures 600-1400 C, surtout par voies thermogravimetrique et micrographique. Le mecanisme de la reaction a ete precise; en particulier, il a ete montre que la brisure de la courbe d'Arrhenius traduisant sa cinetique, qui se produit a 950 C environ, resulte d'une stimulation de la diffusion dans la pellicule de protoxyde de nickel au dessous de

Fluorescence lifetime imaging of oxygen in dental biofilm

Science.gov (United States)

Gerritsen, Hans C.; de Grauw, Cees J.

2000-12-01

Dental biofilm consists of micro-colonies of bacteria embedded in a matrix of polysaccharides and salivary proteins. pH and oxygen concentration are of great importance in dental biofilm. Both can be measured using fluorescence techniques. The imaging of dental biofilm is complicated by the thickness of the biofilms that can be up to several hundred micrometers thick. Here, we employed a combination of two-photon excitation microscopy with fluorescence lifetime imaging to quantify the oxygen concentration in dental biofilm. Collisional quenching of fluorescent probes by molecular oxygen leads to a reduction of the fluorescence lifetime of the probe. We employed this mechanism to measure the oxygen concentration distribution in dental biofilm by means of fluorescence lifetime imaging. Here, TRIS Ruthenium chloride hydrate was used as an oxygen probe. A calibration procedure on buffers was use to measure the lifetime response of this Ruthenium probe. The results are in agreement with the Stern-Volmer equation. A linear relation was found between the ratio of the unquenched and the quenched lifetime and the oxygen concentration. The biofilm fluorescence lifetime imaging results show a strong oxygen gradient at the buffer - biofilm interface and the average oxygen concentration in the biofilm amounted to 50 μM.

Modeling of Cerebral Oxygen Transport Based on In vivo Microscopic Imaging of Microvascular Network Structure, Blood Flow, and Oxygenation.

Science.gov (United States)

Gagnon, Louis; Smith, Amy F; Boas, David A; Devor, Anna; Secomb, Timothy W; Sakadžić, Sava

2016-01-01

Oxygen is delivered to brain tissue by a dense network of microvessels, which actively control cerebral blood flow (CBF) through vasodilation and contraction in response to changing levels of neural activity. Understanding these network-level processes is immediately relevant for (1) interpretation of functional Magnetic Resonance Imaging (fMRI) signals, and (2) investigation of neurological diseases in which a deterioration of neurovascular and neuro-metabolic physiology contributes to motor and cognitive decline. Experimental data on the structure, flow and oxygen levels of microvascular networks are needed, together with theoretical methods to integrate this information and predict physiologically relevant properties that are not directly measurable. Recent progress in optical imaging technologies for high-resolution in vivo measurement of the cerebral microvascular architecture, blood flow, and oxygenation enables construction of detailed computational models of cerebral hemodynamics and oxygen transport based on realistic three-dimensional microvascular networks. In this article, we review state-of-the-art optical microscopy technologies for quantitative in vivo imaging of cerebral microvascular structure, blood flow and oxygenation, and theoretical methods that utilize such data to generate spatially resolved models for blood flow and oxygen transport. These "bottom-up" models are essential for the understanding of the processes governing brain oxygenation in normal and disease states and for eventual translation of the lessons learned from animal studies to humans.

Sterilization by pure oxygen plasma and by oxygen-hydrogen peroxide plasma: an efficacy study.

Science.gov (United States)

Boscariol, M R; Moreira, A J; Mansano, R D; Kikuchi, I S; Pinto, T J A

2008-04-02

Plasma is an innovative sterilization method characterized by a low toxicity to operators and patients, and also by its operation at temperatures close to room temperatures. The use of different parameters for this method of sterilization and the corresponding results were analyzed in this study. A low-pressure inductive discharge was used to study the plasma sterilization processes. Oxygen and a mixture of oxygen and hydrogen peroxide were used as plasma source gases. The efficacy of the processes using different combinations of parameters such as plasma-generation method, type of gas, pressure, gas flow rate, temperature, power, and exposure time was evaluated. Two phases were developed for the processes, one using pure oxygen and the other a mixture of gases. Bacillus subtilis var. niger ATCC 9372 (Bacillus atrophaeus) spores inoculated on glass coverslips were used as biological indicators to evaluate the efficacy of the processes. All cycles were carried out in triplicate for different sublethal exposure times to calculate the D value by the enumeration method. The pour-plate technique was used to quantify the spores. D values of between 8 and 3 min were obtained. Best results were achieved at high power levels (350 and 400 W) using pure oxygen, showing that plasma sterilization is a promising alternative to other sterilization methods.

The development of zirconia membrane oxygen separation technology

International Nuclear Information System (INIS)

Chiacchi, F.T.; Badwal, S.P.S.; Velizko, V.

2000-01-01

The oxygen separation technology based on ceramic membranes constructed from stabilised zirconia is currently under development for applications ranging from oxygen generation or air enrichment for medical use to control of oxygen concentration or oxygen removal from gas streams and enclosures for semiconductor, food packaging and process control instrumentation industries. The technology is based on a rugged tubular design with extensive thermal cycling capability. Several single and three tube devices have been operated for periods up to 5000h. An eight tube module, as a building block for larger scale oxygen production or removal devices, has been constructed and is being evaluated. In this paper, the construction of the device, oxygen generating capacity, life time tests and performance of the ceramic membrane device under development at CSIRO will be discussed. Copyright (2000) The Australian Ceramic Society

Oxygen negative glow: reactive species and emissivity

International Nuclear Information System (INIS)

Sahli, Khaled

1991-01-01

This research thesis addresses the study of a specific type of oxygen plasma created by electron beams (1 keV, 20 mA/cm"2), negative glow of a luminescent discharge in abnormal regime. The objective is to test the qualities of this plasma as source of two 'active' species of oxygen (singlet molecular oxygen and atomic oxygen) which are useful in applications. The experiment mainly bears on the use of VUV (120 to 150 nm) absorption spectroscopy measurements of concentrations of these both species, and on the recording of plasma emissivity space profiles in the visible region (450 to 850 nm). It appears that low concentrations of singlet oxygen definitely exclude this type of discharge for iodine laser applications. On the contrary, concentrations measured for atomic oxygen show it is a good candidate for the oxidation of large surfaces by sheets of beams. The satisfying comparison of emissivity results with a published model confirm the prevailing role of fast electrons, and gives evidence of an important effect of temperature: temperature can reach 1000 K, and this is in agreement with the presented measurement [fr

Production of an accelerated oxygen-14 beam

International Nuclear Information System (INIS)

Powell, J.; O'Neil, J.P.; Cerny, Joseph

2003-01-01

BEARS is an ongoing project to provide a light-ion radioactive-beam capability at the 88-Inch Cyclotron at LBNL. Light radioactive isotopes are produced at a 10 MeV proton medical cyclotron, transported 350 m via a high-speed gas transport capillary, cryogenically separated, and injected into the 88-Inch Cyclotron's ion source. The first radioactive beam successfully accelerated was carbon-11 and beams of intensity more than 10 8 ions/s have been utilized for experiments. Development of oxygen-14 as the second BEARS beam presented considerable technical challenges, both due to its short half-life of 71 s and the radiation chemistry of oxygen in the target. The usual techniques developed for medical uses of oxygen-15 involve the addition of significant amounts of carrier oxygen, something that would overload the ion source. As a solution, oxygen-14 is produced as water in a carrier-free form, and is chemically converted in two steps to carbon dioxide, a form readily usable by the BEARS. This system has been built and is operational, and initial tests of accelerating an oxygen-14 beam have been performed

Experimental study on ceramic membrane technology for onboard oxygen generation

Directory of Open Access Journals (Sweden)

Jiang Dongsheng

2016-08-01

Full Text Available The ceramic membrane oxygen generation technology has advantages of high concentration of produced oxygen and potential nuclear and biochemical protection capability. The present paper studies the ceramic membrane technology for onboard oxygen generation. Comparisons are made to have knowledge of the effects of two kinds of ceramic membrane separation technologies on oxygen generation, namely electricity driven ceramic membrane separation oxygen generation technology (EDCMSOGT and pressure driven ceramic membrane separation oxygen generation technology (PDCMSOGT. Experiments were conducted under different temperatures, pressures of feed air and produced oxygen flow rates. On the basis of these experiments, the flow rate of feed air, electric power provided, oxygen recovery rate and concentration of produced oxygen are compared under each working condition. It is concluded that the EDCMSOGT is the oxygen generation means more suitable for onboard conditions.

Improvement of AD Biosynthesis Response to Enhanced Oxygen Transfer by Oxygen Vectors in Mycobacterium neoaurum TCCC 11979.

Science.gov (United States)

Su, Liqiu; Shen, Yanbing; Gao, Tian; Luo, Jianmei; Wang, Min

2017-08-01

In steroid biotransformation, soybean oil can improve the productivity of steroids by increasing substrate solubility and strengthen the cell membrane permeability. However, little is known of its role as oxygen carrier and its mechanism of promoting the steroid biotransformation. In this work, soybean oil used as oxygen vector for the enhancement of androst-4-ene-3,17-dione (AD) production by Mycobacterium neoaurum TCCC 11979 (MNR) was investigated. Upon the addition of 16% (v/v) soybean oil, the volumetric oxygen transfer coefficient (K L a) value increased by 44%, and the peak molar yield of AD (55.76%) was achieved. Analysis of intracellular cofactor levels showed high NAD + , ATP level, and a low NADH/NAD + ratio. Meanwhile, the two key enzymes of the tricarboxylic acid (TCA) cycle, namely, isocitrate dehydrogenase and α-ketoglutarate dehydrogenase, were upregulated after incubation with soybean oil. These enhancements induced by the increasing of oxygen supply showed positive effects on phytosterol (PS) bioconversion. Results could contribute to the understanding of effects of soybean oil as oxygen vector on steroid biotransformation and provided a convenient method for enhancing the efficiency of aerobic steroid biocatalysis.

DEVICE FOR CONTROL OF OXYGEN PARTIAL PRESSURE

Science.gov (United States)

Bradner, H.; Gordon, H.S.

1957-12-24

A device is described that can sense changes in oxygen partial pressure and cause a corresponding mechanical displacement sufficient to actuate meters, valves and similar devices. A piston and cylinder arrangement contains a charge of crystalline metal chelate pellets which have the peculiar property of responding to variations in the oxygen content of the ambient atmosphere by undergoing a change in dimension. A lever system amplifies the relative displacement of the piston in the cylinder, and actuates the controlled valving device. This partial pressure oxygen sensing device is useful in controlled chemical reactions or in respiratory devices such as the oxygen demand meters for high altitude aircraft.

Oxygen depletion of bismuth molybdates

Energy Technology Data Exchange (ETDEWEB)

Yong, L.K.; Howe, R.F.; Keulks, G.W.; Hall, W.K.

1978-05-01

Pure ..cap alpha..-phase bismuth molybdate (Bi/sub 2/Mo/sub 3/O/sub 12/), which is known to be weakly active for selective oxidation, and pure ..gamma..-phase bismuth molybdate (Bi/sub 2/MoO/sub 6/), which has good activity, were subjected to oxidation-reduction cycles with known amounts of hydrogen and oxygen, at 300/sup 0/-570/sup 0/C and with evacuation steps between treatments. The volume of oxygen consumed during reoxidation was equal to half the hydrogen consumed during the reduction on the ..cap alpha..-phase, which indicated that no hydrogen was retained during reduction. For the ..gamma..-phase, the oxygen consumption was greater than half of the hydrogen consumption and it increased with extent of reduction. The excess oxygen was apparently consumed by filling anion vacancies formed during outgassing subsequent to the reduction step. ESR spectroscopy and temperature-programed oxidation-reduction indicated that lattice oxide ions which bridge between bismuth and molybdenum layers of the koechlinite structure become more labile when the catalyst is in a partially reduced state, and that this effect is greater in the ..gamma..- than the ..cap alpha..-phase. Table and 15 references.

Résultats de recherche | Page 409 | CRDI - Centre de recherches ...

International Development Research Centre (IDRC) Digital Library (Canada)

La fin de la guerre froide devait inaugurer une nouvelle ère de paix et de sécurité internationale. Au lieu de cela, des conflits d'un nouveau type se sont déclarés et la communauté internationale a dû réagir rapidement. Publication Date. 1 janvier 1998. Livres.

Oxygen diffusion in glasses and ceramic materials

International Nuclear Information System (INIS)

Kolitsch, A.; Richter, E.; Wolf, M.

1978-10-01

A survey is given on the published works to study oxygen diffusion in glasses and ceramic materials in the last years. In the first part methods are described for the measurement of oxygen diffusion coefficients and in the second part the published reports on oxygen diffusion in glasses, ceramic and other oxides are discussed. The most important results are summarized in different tables. (author)

Oxygenation and hemodynamics in left and right cerebral hemispheres during induction of veno-arterial extracorporeal membrane oxygenation.

NARCIS (Netherlands)

Heyst, A.F.J. van; Liem, D.; Hopman, J.C.W.; Staak, F.H.J.M. van der; Sengers, R.C.A.

2004-01-01

OBJECTIVE: Oxygenation and hemodynamics in the left and right cerebral hemispheres were measured during induction of veno-arterial extracorporeal membrane oxygenation (VA-ECMO). STUDY DESIGN: Using near infrared spectrophotometry, effects of right common carotid artery (RCCA) and right internal

Novel Membranes and Processes for Oxygen Enrichment

Energy Technology Data Exchange (ETDEWEB)

Lin, Haiqing

2011-11-15

The overall goal of this project is to develop a membrane process that produces air containing 25-35% oxygen, at a cost of $25-40/ton of equivalent pure oxygen (EPO2). Oxygen-enriched air at such a low cost will allow existing air-fueled furnaces to be converted economically to oxygen-enriched furnaces, which in turn will improve the economic and energy efficiency of combustion processes significantly, and reduce the cost of CO{sub 2} capture and sequestration from flue gases throughout the U.S. manufacturing industries. During the 12-month Concept Definition project: We identified a series of perfluoropolymers (PFPs) with promising oxygen/nitrogen separation properties, which were successfully made into thin film composite membranes. The membranes showed oxygen permeance as high as 1,200 gpu and oxygen/nitrogen selectivity of 3.0, and the permeance and selectivity were stable over the time period tested (60 days). We successfully scaled up the production of high-flux PFP-based membranes, using MTR's commercial coaters. Two bench-scale spiral-wound modules with countercurrent designs were made and parametric tests were performed to understand the effect of feed flow rate and pressure, permeate pressure and sweep flow rate on the membrane module separation properties. At various operating conditions that modeled potential industrial operating conditions, the module separation properties were similar to the pure-gas separation properties in the membrane stamps. We also identified and synthesized new polymers [including polymers of intrinsic microporosity (PIMs) and polyimides] with higher oxygen/nitrogen selectivity (3.5-5.0) than the PFPs, and made these polymers into thin film composite membranes. However, these membranes were susceptible to severe aging; pure-gas permeance decreased nearly six-fold within two weeks, making them impractical for industrial applications of oxygen enrichment. We tested the effect of oxygen-enriched air on NO{sub x} emissions

Long-term domiciliary oxygen therapy – the Johannesburg hospital ...

African Journals Online (AJOL)

Objectives. To assess the clinical and demographic characteristics of patients attending an oxygen clinic, to assess the relevance of the current clinical criteria determining the need for domiciliary oxygen, to assess the cost-effectiveness of an oxygen clinic and to assess compliance with the oxygen prescription. Design.

Implantable oxygen microelectrode suitable for medium-term investigations of post-surgical tissue hypoxia and changes in tumor tissue oxygenation produced by radiotherapy

International Nuclear Information System (INIS)

Burke, T.R.; Johnson, R.J.; Krishnamsetty, C.B.; Sako, K.; Karakousis, C.; Wojtas, F.

1980-01-01

Teflon-covered platinum oxygen probes were used to monitor tissue oxygen levels in post-surgical cancer patients and those treated with radiotherapy. Progressive wound healing was usually accompanied by a decrease in tissue pO2. Radiotherapy produced a slight increase in pO2 while hyperthermia effected a significant increase in the oxygen level during 100% oxygen breathing

Oxygen diffusion in zircon

Science.gov (United States)

Watson, E. B.; Cherniak, D. J.

1997-05-01

Oxygen diffusion in natural, non-metamict zircon was characterized under both dry and water-present conditions at temperatures ranging from 765°C to 1500°C. Dry experiments were performed at atmospheric pressure by encapsulating polished zircon samples with a fine powder of 18O-enriched quartz and annealing the sealed capsules in air. Hydrothermal runs were conducted in cold-seal pressure vessels (7-70 MPa) or a piston cylinder apparatus (400-1000 MPa) on zircon samples encapsulated with both 18O-enriched quartz and 18O water. Diffusive-uptake profiles of 18O were measured in all samples with a particle accelerator, using the 18O(p, α) 15N reaction. For dry experimental conditions at 1100-1500°C, the resulting oxygen diffusivities (24 in all) are well described by: D dry (m 2/s) = 1.33 × 10 -4exp(-53920/T) There is no suggestion of diffusive anisotropy. Under wet conditions at 925°C, oxygen diffusion shows little or no dependence upon P H 2O in the range 7-1000 MPa, and is insensitive to total pressure as well. The results of 27 wet experiments at 767-1160°C and 7-1000 MPa can be described a single Arrhenius relationship: D wet (m 2/s) = 5.5 × 10 -12exp(-25280/T) The insensitivity of oxygen diffusion to P H 2O means that applications to geologic problems can be pursued knowing only whether the system of interest was 'wet' (i.e., P H 2O > 7MPa ) or 'dry'. Under dry conditions (presumably rare in the crust), zircons are extremely retentive of their oxygen isotopic signatures, to the extent that δ 18O would be perturbed at the center of a 200 μm zircon only during an extraordinarily hot and protracted event (e.g., 65 Ma at 900°C). Under wet conditions, δ 18O may or may not be retained in the central regions of individual crystals, cores or overgrowth rims, depending upon the specific thermal history of the system.

Sartre et sa théorie des émotions : une confrontation avec Erving Goffman

Directory of Open Access Journals (Sweden)

Claude Javeau

2010-06-01

Full Text Available L’auteur confronte les positions de Jean-Paul Sartre et Erving Goffman. Dans son ouvrage de 1938, Esquisse d’une théorie des émotions, Jean-Paul Sartre propose une approche phénoménologique prenant doublement ses distances avec la psychanalyse et le béhaviourisme, posant l’émotion comme dégradation spontanée et vécue de la conscience en face du monde, le corps n’étant étrangement dans ce contexte rien d’autre que la croyance vécue de la conscience. L’auteur compare cette position avec la définition goffmanienne de la « situation sociale », qui identifie l’émotion comme une perturbation dans l’ordre normal du déroulement des interactions circonscrites dans la situation. L’interactionnisme symbolique est confronté à l’existentialisme sartrien et à sa position d’une structure magique sous-jacente du monde, en faisant de l’une le miroir de l’autre. Bien que s’inscrivant tous deux dans le courant phénoménologique, Jean-Paul Sartre et Erving Goffman sont ici saisis dans leur stratégie d’évitement des théories psychologiques. En conclusion est posée la question du statut heuristique à conférer au concept de « magique » invoqué par Jean-Paul Sartre.Sartre and his theory of emotions: a confrontation with GoffmanThe author confronts the positions of Jean-Paul Sartre and Erving Goffman. In his Esquisse d’une théorie des émotions (1938, Jean-Paul Sartre proposes a phenomenological approach. Taking his distances both with psychoanalysis and behaviourism, he places emotion as a spontaneous and experienced degradation of the conscience confronted with the world; the body thus becoming strangely nothing other than the experienced belief of consciousness. The author compares this position with Goffman’s definition of the “social situation”. Here, emotion is identified as a disturbance intervening in the normal order of the sequence of events delimited by the situation. Symbolic

Combined impact of water column oxygen and temperature on internal oxygen status and growth of Zostera marina seedlings and adult shoots

DEFF Research Database (Denmark)

Raun, Ane-Marie Løvendahl; Borum, Jens

2013-01-01

Eelgrass (Zostera marina L.) occasionally experiences severe die-offs during warm summer periods with variable water column oxygen partial pressures (pO). Eelgrass is known to be very intolerant to tissue anoxia with reduced growth and increasing mortality after ≤12h anoxia in the dark...... at temperatures of ≥25°C. In the present study we experimentally examine the impact of combined water column oxygen and temperature on oxygen dynamics in leaf meristems of seedlings and adult shoots to better understand how stressful environmental conditions affect eelgrass oxygen dynamics and subsequent growth...... and mortality. There was a strong interaction between water column oxygen and temperature on meristem pO implying that eelgrass is rather resistant to unfavorable oxygen conditions in winter but becomes increasingly vulnerable in summer, especially at high temperatures. At 25°C meristems became anoxic...

Diffusion coefficients of oxygen and hemoglobin as obtained simultaneously from photometric determination of the oxygenation of layers of hemoglobin solutions

NARCIS (Netherlands)

Spaan, J. A.; Kreuzer, F.; van Wely, F. K.

1980-01-01

The oxygenation of layers of deoxygenated hemoglobin solutions after a sudden exposure to a gas containing oxygen at a partial pressure P1 has been studied by a photometric method. Layer thicknesses varied between 50 and 250 micron, hemoglobin concentrations between 0.1 and 0.34kg/l, and oxygen

Singlet oxygen treatment of tumor cells triggers extracellular singlet oxygen generation, catalase inactivation and reactivation of intercellular apoptosis-inducing signaling.

Science.gov (United States)

Riethmüller, Michaela; Burger, Nils; Bauer, Georg

2015-12-01

Intracellular singlet oxygen generation in photofrin-loaded cells caused cell death without discrimination between nonmalignant and malignant cells. In contrast, extracellular singlet oxygen generation caused apoptosis induction selectively in tumor cells through singlet oxygen-mediated inactivation of tumor cell protective catalase and subsequent reactivation of intercellular ROS-mediated apoptosis signaling through the HOCl and the NO/peroxynitrite signaling pathway. Singlet oxygen generation by extracellular photofrin alone was, however, not sufficient for optimal direct inactivation of catalase, but needed to trigger the generation of cell-derived extracellular singlet oxygen through the interaction between H2O2 and peroxynitrite. Thereby, formation of peroxynitrous acid, generation of hydroxyl radicals and formation of perhydroxyl radicals (HO2(.)) through hydroxyl radical/H2O2 interaction seemed to be required as intermediate steps. This amplificatory mechanism led to the formation of singlet oxygen at a sufficiently high concentration for optimal inactivation of membrane-associated catalase. At low initial concentrations of singlet oxygen, an additional amplification step needed to be activated. It depended on singlet oxygen-dependent activation of the FAS receptor and caspase-8, followed by caspase-8-mediated enhancement of NOX activity. The biochemical mechanisms described here might be considered as promising principle for the development of novel approaches in tumor therapy that specifically direct membrane-associated catalase of tumor cells and thus utilize tumor cell-specific apoptosis-inducing ROS signaling. Copyright © 2015 The Authors. Published by Elsevier B.V. All rights reserved.