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Sample records for transfert application au

  1. Transfert radiatif entre une petite particule et un diélectrique: application au chauffage local

    Science.gov (United States)

    Mulet, J.-P.; Joulain, K.; Carminati, R.; Greffet, J. J.

    2002-06-01

    nous montrons dans cette étude que le transfert radiatif entre une particule de taille nanométrique et un diélectrique petit être très important lorsque les distances mises en jeu sont petites devant la longueur d'onde caractéristique du rayonnement thermique. Ce transfert peut devenir dominant lorsque les matériaux utilisés sont polaires. Nous discuterons de la possibilité d'appliquer ces résultats au chauffage local dans les nano-structures.

  2. Transferts aux petites échelles : application au rayonnement thermique, aux forces de Casimir et à la conduction thermique

    OpenAIRE

    Joulain, Karl

    2006-01-01

    Cette habilitation traite des transferts de chaleur et de quantité de mouvement aux courtes échelles d'espace et de temps. Une première partie du travail s'interesse au propriétés du rayonnement thermique en champ proche. Il est montré qu'en présence de matériaux supportant des ondes de surface, le champ électromagnétique d'origine thermique peut voir ses propriétés de cohérence changées entre le champ proche et le champ lointain, en particulier lorsque les matériaux mis en jeu supportent des...

  3. Effets diffractifs et fonction de transfert de l'atmosphère à grande distance: Application au 'rumble' du bang sonique

    OpenAIRE

    Delorme, Philippe

    2010-01-01

    National audience; La propagation dans l'atmosphère du bang sonique est un phénomène complexe. Du point de vue des résultats expérimentaux fondés sur le bang sonique du Concorde, on peut distinguer quatre zones: champ proche (quelques longueurs du mobile), champ moyen (trace au sol dans la carpette primaire, fin des effets non-linéaires), champ lointain ( entre 50 et 500 kilomètres ), champ très lointain ( au delà de 500 kilomètres). La première zone se modélise avec les équations de la mécan...

  4. Christophe Couderc, dir., Le théâtre Espagnol du Siècle d'Or en France. De la traduction au transfert culturel

    Directory of Open Access Journals (Sweden)

    Christian Andrès

    2012-12-01

    Full Text Available Review of Christophe Couderc, Le théâtre Espagnol du Siècle d'Or en France. De la traduction au transfert culturel, Presses Universitaires de Paris Ouest, París, 2012, 299 pp. ISBN: 978-2-84016-102-8.

  5. UO{sub 2}-can thermal transfer. Application to the case of the first EL 4 batch of fuel elements; Transfert thermique UO{sub 2}-gaine. Application au cas de l'element combustible du 1. jeu EL 4

    Energy Technology Data Exchange (ETDEWEB)

    Ringot, C.; Faussat, A. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1964-07-01

    The UO{sub 2}-can thermal transfer is one of the most important factors affecting the operational working of fuel elements. A systematic study of the elements influencing the heat transfer coefficient has been undertaken: in particular the effects of the contact pressure and of the gas filling pressure have been studied. Tests have been carried out using planar and cylindrical geometrical shapes. Using the values obtained and the integral conductivity curve for UO{sub 2}, a calculation has been made of the evolution of the EL-4 fuel element during its life-time, if it is assumed that the fusion gas occupies a free volume of 2,5 per cent at the end of the fuel element and of zero or 2 per cent in the UO{sub 2}. (authors) [French] Le transfert thermique UO{sub 2}-gaine est un des facteurs importants du mode de fonctionnement des elements combustibles. L'etude systematique des elements intervenant dans le coefficient de transfert thermique a ete entreprise: on a notamment etudie l'influence de la pression de contact et de l'atmosphere de remplissage. Des essais ont ete faits en geometrie plane et en geometrie cylindrique. A partir des valeurs obtenues et de la courbe d'integrale de conductibilite de l'UO{sub 2} on a fait un calcul de l'evolution de l'element combustible EL-4 au cours de sa vie, en admettant un volume libre alloue aux gaz de fission place en extremite du crayon egal a 2,5 pour cent et en supposant que le volume libre alloue dans l'UO{sub 2} est nul ou egal a 2 pour cent. (auteurs)

  6. Bringing Down the Barriers to Information Transfer (L’Abaissement des Barrieres s’Opposant au Transfert de l’Information)

    Science.gov (United States)

    1992-02-01

    71 Alcala de Henares (Madrid). Spain Ms M.GONZAI.EZ GONZALEZ Comision Nacional del Mercado de Valores. Pa. de la Castellana 19. 2-KO46 Madrid. Spain Mr...Mrs A. KNECH-T CRISTOBAL lostituto, Juan March de Estudios e Investigaciones. Spain Prof. Dr G.E. KNORZt Fachhochschule Darmstadt, Department of...FRANCE AGARD CONFERENCE PROCEEDINGS 505 Bringing down the Barriers to Information Transfer (LAbaissement des Barrires s’Opposant auTransfert de

  7. Les cartographies de connaissances pour le transfert de connaissances : étude de cas au sein du Groupe Total

    OpenAIRE

    Sellin, Kelly; Dudezert, Aurélie; Binot, Christophe

    2008-01-01

    Le transfert de connaissances est un processus complexe qui se définit à la fois comme un processus social, individuel et organisationnel ; il vise ainsi une transmission des connaissances, leur appropriation par des individus, et leur intégration dans l'organisation. Le transfert s'inscrit par conséquent dans une perspective individuelle et globale de gestion des connaissances, que proposent de modéliser les cartographies de connaissances. À travers une étude menée chez Total, nous explorons...

  8. A Phenomenological Heat Transfer Model of SI Engines – Application to the Simulation of a Full-Hybrid Vehicle Un modèle phénoménologique de transfert thermique au sein de moteurs à allumage commandé — Application à la simulation d’un véhicule full-hybride

    Directory of Open Access Journals (Sweden)

    Dubouil R.

    2013-02-01

    ICE on its thermal behaviour. Especially, it appears that the efficiency of the engine is less penalized than expected by the cold state of the engine. Finally, a parametric study of the modeled engine and a research of a possible optimization of the engine efficiency and the warm-up period are done. Un véhicule hybride électrique permet des économies de carburant non négligeables grâce à une meilleure utilisation du Moteur à Combustion Interne (MCI sur des points de régime-charge à meilleurs rendements. Cependant ce fonctionnement particulier a un impact sur le comportement thermique du MCI, en particulier, pendant sa période de chauffe après un départ à froid. En effet, le moteur peut être arrêté lorsque le véhicule est à l’arrêt (système Stop&Start ainsi que pendant les phases de propulsion en électrique pur (possible à vitesse faible si l’état de charge de la batterie est suffisamment élevé entraînant un manque de source de chaleur et donc un ralentissement du réchauffement du moteur. De plus, l’utilisation du MCI avec des charges plus importantes lors de la recharge des batteries provoque une augmentation de la puissance thermique disponible issue de la combustion. Les stratégies de contrôle d’un véhicule hybride (répartition d’énergie entre les deux types de propulsion : thermique et électrique ont un effet important sur sa consommation finale. Ainsi, la simulation phénoménologique 0D de véhicules hybrides est utile afin d’évaluer l’efficacité de ces stratégies. Cependant, il existe un nombre très limité d’études où la période de chauffe du moteur thermique est prise en compte dans ce type de simulations. Un outil de simulation utilisant le logiciel Amesim a été développé afin de simuler la montée en température du MCI utilisé dans un système de propulsion hybride parallèle. Le modèle est construit afin de prendre en compte les phénomènes thermiques ayant lieu au sein de cet élément. Un

  9. Colons, minorités, immigrés... : Une analyse des luttes de nomination des populations minoritaires consécutives au transfert du droit européen sur les minorités en Lettonie

    OpenAIRE

    Bonnard, Pascal

    2011-01-01

    L'analyse des prises de position des députés du Parlement letton lors des débats relatifs à la ratification de la Convention-cadre pour la protection des minorités nationales permet d'interroger les usages du droit en vue de définir les minorités en tant que groupes et de déterminer leur statut au sein de la société. Le transfert du droit européen sur les minorités a suscité une modification de la désignation des populations minoritaires et de la politique à leur égard : on observe le bascule...

  10. Propagation du bruit des erreurs expérimentales dans les modèles théoriques gérés par des systèmes linéaires. Deux applications en transfert thermique

    Science.gov (United States)

    Depecker, P.; Draoui, A.; Beghein, Cl.

    1992-01-01

    This paper reports sensitivity analysis relative to the field of uncertainty of experimental measured parameters used as model imputs. After describing the experimental uncertainty and its consequences, we present the mathematical tool adapted to models based on linear system resolution. Using examples from heat transfer field, we report two of the most common situations arising to the physicist. The former situation comes up to the experimenter who cannot determine directly some characteristics of his physical system. As the direct measurement of these characteristics is impossible, they are calculated from a model representing the experimental set up. The latter occurs to the model builder, who developes a theoretical model. Building such a model requires knowledge of physical basic characteristics, supposed to be previously determined from experimental measurement. In both cases, measurement induces unertainties spreading into the models. The first application of these principles deals with the study of radiant emitters in real scale dwelling cells. The second one refers to the modeling of coupled heat transfer in a semi-transparent medium such as glass. From both examples, the author point out that the stability of model solutions should be checked, such a stability being not a priori detectable. Ce texte introduit la notion de sensibilité des modèles aux incertitudes avec lesquelles on connaît les paramètres mesurés expérimentalement (donc entachés d'erreurs) entrant dans le formalisme de ces modèles. Après avoir exposé une problématique générale de l'erreur expérimentale et de ses conséquences, on décrit l'outillage mathématique permettant de cerner la question dans le cas des modèles fondés sur des systèmes linéaires. On s'intéresse ensuite aux deux situations les plus classiques dans lesquelles peut se trouver le physicien, en s'appuyant sur des exemples empruntés au domaine des transferts thermiques. La première est celle de l

  11. Au Based Nanocomposites Towards Plasmonic Applications

    Science.gov (United States)

    Panniello, A.; Curri, M. L.; Placido, T.; Reboud, V.; Kehagias, N.; Sotomayor Torres, C. M.; Mecerreyes, D.; Agostiano, A.; Striccoli, M.

    2010-06-01

    Incorporation of nano-sized metals in polymers can transfer their unique features to the host matrix, providing nanocomposite materials with improved optical, electric, magnetic and mechanical properties. In this work, colloidal Au nanorods have been incorporated into PMMA based random co-polymer, properly functionalized with amino groups and the optical and morphological properties of the resulting nanocomposite have been investigated by spectroscopic and AFM measurements. Au nanorods have demonstrated to preserve the plasmon absorption and to retain morphological features upon the incorporation, thus making the final metal modified polymer composite exploitable for the fabrication of plasmonic devices. The prepared nanocomposites have been then patterned by Nano Imprint Lithography technique in order to demonstrate the viability of the materials towards optical applications.

  12. Transferts intergénérationnels, vieillissement de la population et ...

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

    Les chercheurs adopteront une nouvelle approche globale, la méthodologie des comptes de transferts nationaux (National Transfer Accounts, NTA), afin de mesurer l'ensemble des flux économiques au fil du temps. Un des principaux avantages de cette méthode réside dans la prise en compte, dans ses estimations, des ...

  13. TRANSFERT THERMIQUE INSTATIONNAIRE DANS UN MUR TRICOUCHES SUBISSANT UN CHANGEMENT DE PHASE PAR SOLIDIFICATION.

    OpenAIRE

    O Arfi; E Mezaache

    2016-01-01

    Une étude numérique du transfert de chaleur instationnaire dans un mur tricouches est présentée. Le modèle physique est basé sur l’équation de conduction thermique unidirectionnelle en tenant compte des équations de couplages au niveau des interfaces et des conditions convectives de surfaces. Les équations de transfert sont données en représentation enthalpique pour le matériau à changement de phase (MCP), et en formulation générale pour les régions solides. La formulation adimensionnelle a p...

  14. Coupled transfers; Transferts couples

    Energy Technology Data Exchange (ETDEWEB)

    Nicolas, X.; Lauriat, G.; Jimenez-Rondan, J. [Universite de Marne-la-Vallee, Lab. d' Etudes des Transferts d' Energie et de Matiere (LETEM), 77 (France); Bouali, H.; Mezrhab, A. [Faculte des Sciences, Dept. de Physique, Lab. de Mecanique et Energetique, Oujda (Morocco); Abid, C. [Ecole Polytechnique Universitaire de Marseille, IUSTI UMR 6595, 13 Marseille (France); Stoian, M.; Rebay, M.; Lachi, M.; Padet, J. [Faculte des Sciences, Lab. de Thermomecanique, UTAP, 51 - Reims (France); Mladin, E.C. [Universitaire Polytechnique Bucarest, Faculte de Genie Mecanique, Bucarest (Romania); Mezrhab, A. [Faculte des Sciences, Lab. de Mecanique et Energetique, Dept. de Physique, Oujda (Morocco); Abid, C.; Papini, F. [Ecole Polytechnique, IUSTI, 13 - Marseille (France); Lorrette, C.; Goyheneche, J.M.; Boechat, C.; Pailler, R. [Laboratoire des Composites ThermoStructuraux, UMR 5801, 33 - Pessac (France); Ben Salah, M.; Askri, F.; Jemni, A.; Ben Nasrallah, S. [Ecole Nationale d' Ingenieurs de Monastir, Lab. d' Etudes des Systemes Thermiques et Energetiques (Tunisia); Grine, A.; Desmons, J.Y.; Harmand, S. [Laboratoire de Mecanique et d' Energetique, 59 - Valenciennes (France); Radenac, E.; Gressier, J.; Millan, P. [ONERA, 31 - Toulouse (France); Giovannini, A. [Institut de Mecanique des Fluides de Toulouse, 31 (France)

    2005-07-01

    This session about coupled transfers gathers 30 articles dealing with: numerical study of coupled heat transfers inside an alveolar wall; natural convection/radiant heat transfer coupling inside a plugged and ventilated chimney; finite-volume modeling of the convection-conduction coupling in non-stationary regime; numerical study of the natural convection/radiant heat transfer coupling inside a partitioned cavity; modeling of the thermal conductivity of textile reinforced composites: finite element homogenization on a full periodical pattern; application of the control volume method based on non-structured finite elements to the problems of axisymmetrical radiant heat transfers in any geometries; modeling of convective transfers in transient regime on a flat plate; a conservative method for the non-stationary coupling of aero-thermal engineering codes; measurement of coupled heat transfers (forced convection/radiant transfer) inside an horizontal duct; numerical simulation of the combustion of a water-oil emulsion droplet; numerical simulation study of heat and mass transfers inside a reactor for nano-powders synthesis; reduction of a combustion and heat transfer model of a direct injection diesel engine; modeling of heat transfers inside a knocking operated spark ignition engine; heat loss inside an internal combustion engine, thermodynamical and flamelet model, composition effects of CH{sub 4}H{sub 2} mixtures; experimental study and modeling of the evolution of a flame on a solid fuel; heat transfer for laminar subsonic jet of oxygen plasma impacting an obstacle; hydrogen transport through a A-Si:H layer submitted to an hydrogen plasma: temperature effects; thermal modeling of the CO{sub 2} laser welding of a magnesium alloy; radiant heat transfer inside a 3-D environment: application of the finite volume method in association with the CK model; optimization of the infrared baking of two types of powder paints; optimization of the emission power of an infrared

  15. Évaluation de l'incidence des programmes de transferts en espèces ...

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

    Ce projet examinera la façon dont les transferts conditionnels en espèces (TCE) peuvent aider les femmes pauvres à surmonter les vulnérabilités économiques et évaluera leur aptitude à transformer les relations entre les sexes à la maison et au sein de la collectivité en Tanzanie. Le projet produira de nouvelles données ...

  16. Transferts intergénérationnels, vieillissement de la population et ...

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

    Transferts intergénérationnels, vieillissement de la population et protection sociale en Asie ... Le projet se déroulera en Chine, en Inde, aux Philippines, en Thaïlande et au Vietnam, des pays où l'on observe des bouleversements démographiques et économiques sans précédent et qui ont tous besoin de se doter de ...

  17. Ordered Au Nanodisk and Nanohole Arrays: Fabrication and Applications

    KAUST Repository

    Zheng, Yue Bing

    2010-01-01

    We have utilized nanosphere lithography (NSL) to fabricate ordered Au nanodisk and nanohole arrays on substrates and have studied the localized surface plasmon resonance (LSPR) of the arrays. Through these investigations, we demonstrate that the angle- dependent behavior of the LSPR in the Au nanodisk arrays enables real-time observation of exciton-plasmon couplings. In addition, we show that the NSL-fabricated Au nanohole arrays can be applied as templates for patterning micro-/nanoparticles under capillary force. The unique structural and plasmonic characteristics of the Au nanodisk and nano- hole arrays, as well as the low-cost and high-throughput NSL-based nanofabrication technique, render these arrays excellent platforms for numerous engineering applications. © 2010 by ASME.

  18. and Au nanoparticles for SERS applications

    Directory of Open Access Journals (Sweden)

    Fazio Enza

    2018-01-01

    Full Text Available The morphological and optical properties of noble metal nanoparticles prepared by picosecond laser generated plasmas in water were investigated. First, the ablation efficiency was maximized searching the optimal focusing conditions. The nanoparticle size, measured by Scanning Transmission Electron Microscopy, strongly depends on the laser fluence, keeping fixed the other deposition parameters such as the target to scanner objective distance and laser repetition frequency. STEM images indicate narrow gradients of NP sizes. Hence the optimization of ablation parameters favours a fine tuning of nanoparticles. UV-Visible spectroscopy helped to determine the appropriate laser wavelength to resonantly excite the localized surface plasmon to carry out Surface Enhanced Raman Scattering (SERS measurements. The SERS activity of Ag and Au substrates, obtained spraying the colloids synthesized in water, was tested using crystal violet as a probe molecule. The good SERS performance, observed at excitation wavelength 785 nm, is attributed to aggregation phenomena of nanoparticles sprayed on the support.

  19. UTILISATION DU MODÈLE ÉCREVISSE COMME ESPÈCE BIOINDICATRICE DE POLLUTION. APPLICATION À L’ÉTUDE DES TRANSFERTS TROPHIQUES DU CADMIUM

    Directory of Open Access Journals (Sweden)

    SIMON O.

    2002-07-01

    Full Text Available La bioaccumulation des métaux par les organismes aquatiques est directement liée aux modalités d’exposition : contamination directe via le milieu ou contamination trophique via l’ingestion de proies contaminées. Pour appréhender les perturbations des écosystèmes, il apparaît important de déterminer des espèces « bioindicatrices » et de mesurer la part respective de ces deux voies d’exposition. Les travaux présentés concernent le transfert trophique du cadmium entre une proie, le bivalve benthique Corbicula fluminea, et un de ses prédateurs, l’écrevisse Astacus astacus. Afin d’insister sur l’importance des modalités de prédation de ce crustacé, nous avons réalisé 2 approches expérimentales complémentaires. La première concerne la consommation « naturelle » de proies contaminées pendant 30 jours d’exposition, la seconde consiste à introduire directement un bol alimentaire de proies contaminées dans l’estomac des écrevisses par une technique de gavage. Les résultats montrent une différence importante entre ces deux approches expérimentales.

  20. Radiant heat transfers in turbojet engines. Two applications, three levels of modeling; Transferts radiatifs dans les foyers de turboreacteurs. Deux applications, trois niveaux de modelisation

    Energy Technology Data Exchange (ETDEWEB)

    Schultz, J.L.; Desaulty, M. [SNECMA, Centre de Villaroche, 77 - Moissy-Cramayel (France); Taine, J. [Ecole Centrale de Paris, Laboratoire EM2C. CNRS, 92 - Chatenay-Malabry (France)

    1996-12-31

    Several applications linked with the dimensioning of turbojet engines require the use of modeling of radiant heat transfers. Two different applications are presented in this study: the modeling of heat transfers in the main combustion chamber, and modeling of the infrared signature of the post-combustion chamber of a military engine. In the first application, two types of radiant heat transfer modeling are presented: a global modeling based on empirical considerations and used in rapid pre-dimensioning methods, and a modeling based on a grey gases concept and combined to a ray shooting type technique allowing the determination of local radiant heat flux values. In the second application, a specific modeling of the radiant heat flux is used in the framework of a ray shooting method. Each model represents a different level of successive approximations of the radiant heat transfer adapted to flow specificities and to the performance requested. (J.S.) 16 refs.

  1. TRANSFERT THERMIQUE INSTATIONNAIRE DANS UN MUR TRICOUCHES SUBISSANT UN CHANGEMENT DE PHASE PAR SOLIDIFICATION.

    Directory of Open Access Journals (Sweden)

    O Arfi

    2016-05-01

    Full Text Available Une étude numérique du transfert de chaleur instationnaire dans un mur tricouches est présentée. Le modèle physique est basé sur l’équation de conduction thermique unidirectionnelle en tenant compte des équations de couplages au niveau des interfaces et des conditions convectives de surfaces. Les équations de transfert sont données en représentation enthalpique pour le matériau à changement de phase (MCP, et en formulation générale pour les régions solides. La formulation adimensionnelle a permis de dégager les principaux paramètres affectant le transfert : nombre de Biot (Bi, nombre de Stephan (Ste et le degré de surchauffe (qm. La discrétisation des équations est réalisée en utilisant la méthode des volumes finis selon un schéma explicite. La solution numérique est obtenue par une méthode itérative basée sur la notion d’enthalpie critique. L’étude de l’influence de la condition convective chaude, gouvernée par  Bi¥,cet θ¥,c , a montré que la présence des couches solides affecte la cinétique de la solidification, les limites de la solidification et le transfert de chaleur par un effet de stockage et de déstockage d’énergie sensible. L’influence de la température θ¥,c sur le processus de changement de phase est fortement dépendante du nombre de Biot Bi¥,c.

  2. TiAu-based micro-calorimeters for space applications

    International Nuclear Information System (INIS)

    Dirks, B.P.F.; Popescu, M.; Bruijn, M.; Gottardi, L.; Hoevers, H.F.C.; Korte, P.A.J. de; Kuur, J. van der; Ridder, M.; Takei, Y.

    2009-01-01

    We present the latest results of the performance of micro-calorimeters based on transition edge sensors (TESs) for space applications. Sensors based on TiAu superconductive layers with Cu/Bi absorbers are discussed and have been characterized. Different coupling schemes between absorber and TES have been tested leading to an optimal (preferred) design for a new batch of arrays. We discuss the progress on array development for the International X-ray Observatory (IXO) in terms of pixel uniformity and filling factor. Inter-pixel cross-talk is discussed as well.

  3. Hydrothermal Cation Exchange Enabled Gradual Evolution of Au@ZnS–AgAuS Yolk–Shell Nanocrystals and Their Visible Light Photocatalytic Applications

    Science.gov (United States)

    Feng, Jingwen; Liu, Jia; Cheng, Xiaoyan; Liu, Jiajia; Xu, Meng

    2017-01-01

    Abstract Yolk–shell hybrid nanoparticles with noble metal core and programmed semiconductor shell composition may exhibit synergistic effects and tunable catalytic properties. In this work, the hydrothermal cation exchange synthesis of Au@ZnS–AgAuS yolk–shell nanocrystals (Y–S NCs) with well‐fabricated void size, grain‐boundary‐architectured ZnS–AgAuS shell and in situ generated Au cocatalyst are demonstrated. Starting from the novel cavity‐free Au@AgAuS core‐shell NCs, via aqueous cation exchange reaction with Zn2+, the gradual evolution with produced Au@ZnS–AgAuS Y–S NCs can be achieved successfully. This unprecedented evolution can be reasonably explained by cation exchange initialized chemical etching of Au core, followed by the diffusion through the shell to be AgAuS and then ZnS. By hydrothermal treatment provided optimal redox environment, Au ions in shell were partially reduced to be Au NCs on the surface. The UV–vis absorption spectra evolution and visible light photocatalytic performances, including improved photodegradation behavior and photocatalytic hydrogen evolution activity, have demonstrated their potential applications. This new one‐pot way to get diverse heterointerfaces for better photoinduced electron/hole separation synergistically can be anticipated for more kinds of photocatalytic organic synthesis. PMID:29375968

  4. Hydrothermal Cation Exchange Enabled Gradual Evolution of Au@ZnS-AgAuS Yolk-Shell Nanocrystals and Their Visible Light Photocatalytic Applications.

    Science.gov (United States)

    Feng, Jingwen; Liu, Jia; Cheng, Xiaoyan; Liu, Jiajia; Xu, Meng; Zhang, Jiatao

    2018-01-01

    Yolk-shell hybrid nanoparticles with noble metal core and programmed semiconductor shell composition may exhibit synergistic effects and tunable catalytic properties. In this work, the hydrothermal cation exchange synthesis of Au@ZnS-AgAuS yolk-shell nanocrystals (Y-S NCs) with well-fabricated void size, grain-boundary-architectured ZnS-AgAuS shell and in situ generated Au cocatalyst are demonstrated. Starting from the novel cavity-free Au@AgAuS core-shell NCs, via aqueous cation exchange reaction with Zn 2+ , the gradual evolution with produced Au@ZnS-AgAuS Y-S NCs can be achieved successfully. This unprecedented evolution can be reasonably explained by cation exchange initialized chemical etching of Au core, followed by the diffusion through the shell to be AgAuS and then ZnS. By hydrothermal treatment provided optimal redox environment, Au ions in shell were partially reduced to be Au NCs on the surface. The UV-vis absorption spectra evolution and visible light photocatalytic performances, including improved photodegradation behavior and photocatalytic hydrogen evolution activity, have demonstrated their potential applications. This new one-pot way to get diverse heterointerfaces for better photoinduced electron/hole separation synergistically can be anticipated for more kinds of photocatalytic organic synthesis.

  5. ‘Choses Virtuelles. Les Objects Matériels Perdus Ou Trouvés Dans Les Études De Transfert Culturel’

    NARCIS (Netherlands)

    Broomans, Pieternella; Andringa, Kim; Harry, Frédérique; Mareuge, Agathe; Terrisse, Bénédicte

    2015-01-01

    Petra Broomans s’attache à deux figures de médiateurs culturels, Constant Jacob Hansen et Philippine Wijsman, pour mettre en lumière le rôle joué par la perte ou la découverte de matériel – concret ou virtuel – dans les études de transfert culturel. L’attention portée au matériel permet de les

  6. Nouvelle formulation de la fonction de transfert d'un laser à nanostructures quantiques pour les applications à la modulation haut-débit et aux phénomènes microscopiques non-linéaires

    OpenAIRE

    Wang, Cheng; Grillot, Frederic; Even, Jacky

    2012-01-01

    National audience; L'exploitation des semi-conducteurs de basse dimensionnalité permet d'améliorer les propriétés des composants optoélectroniques de par un meilleur confinement quantique des électrons et des trous. L'objectif de cette contribution est d'étudier théoriquement les propriétés dynamiques des lasers nano-structurés InAs/InP(311B). Une nouvelle expression de la fonction de transfert en intensité du laser est proposée pour les systèmes à îlots quantiques. Les modèles classiques pou...

  7. États-Unis / France. Transferts culturels dans le domaine des soins infirmiers, 1854-1938

    Directory of Open Access Journals (Sweden)

    Annick Foucrier

    2012-02-01

    Full Text Available Cet ouvrage a pour but de montrer que la professionnalisation des infirmières françaises (dont l'histoire a souvent été confondue avec l'histoire des infirmières de l'Assistance publique de Paris a, en fait, connu une histoire longue et conflictuelle (1854-1938 au cours de laquelle les influences anglaise et étatsunienne ont été très prégnantes. C'est ce transfert culturel que les deux auteures – Nicole Fouché (docteure en histoire et Evelyne Diebolt (docteur d'État en Histoire – se sont ...

  8. Les méthodesthermiques de production des hydrocarbures. Chapitre 1 : transfert de chaleur et de masse Thermal Methods of Hydrocarbon Production. Chapter 1 : Heat and Mass Transfer

    Directory of Open Access Journals (Sweden)

    Bia P.

    2006-11-01

    Full Text Available Après un rappel général sur le transfert de chaleur et de masse ainsi que sur les lois de conservation dans les milieux continus, on traite de l'adaptation de ces lois au cas des milieux poreux. On donne ensuite des informations quantitatives sur les grandeurs physiques mises en jeu par les phénomènes de transfert en milieu poreux. After making a general review of heat and mass transfer a well as of laws of conservation in continua, this chapter describes how these laws con be adopted to the case of porous media. Quantitative data are then given on the physical magnitudes brought into play by transfer phenomena in porous media.

  9. Dynamique institutionnelle des transferts de gestion dans le corridor ...

    African Journals Online (AJOL)

    Ten years after their creation, the operation of the community-based natural resource management policy named 'transfert de gestion' – the 1996 GELOSE law (applied to any kind of natural resources), and the 2001 GCF decree (only applied to forests) - remains little understood. The forest corridor linking Ranomafana and ...

  10. Influence des états d'interface et de la température sur l'inefficacité de transfert des dispositifs à transfert de charge en surface ll SCCD gg

    Science.gov (United States)

    Bouhdada, A.; Touhami, A.

    1994-11-01

    Two phenomena are on the degradation base of the charge transfer inefficiency in the C.C.D. devices : the incomplet transfer of the free charges because of the insuffisance of the transfer time and the charge trapping by the interface state, whose effect is negligible at high frequencies. The aim of this paper is the transfer inefficiency analyze on the absence and presence of interface states. The charges transfer from a potential well to another, is described by a nonlinear differential equation, that introduces all the transfer major mechanisms : self-induced drift E_s (x, t ), fringing field drift E_ff, the thermal diffusion and the recombination-generation phenomenon at the interface described by Shockley-Read-Hall. The numerical method proposed for this equation resolution is based on the implicit fined difference method, which leads to a discretized system of equations, which we solve by using the algorithm Gauss by elimination. In the last stage, we shall discuss the temperature influence on the transfer inefficiency, while introducing in the differential equation all the parameter expressions dependent on the temperature (captor cross section σ_n, thermal velocity V_th, acceptor density N_A, conduction band density of states N_c and the surface mobility of electrons μ_n). La dégradation de l'inefficacité de transfert dans les dispositifs à transfert de charge " CCD " est liée principalement à l'insuffisance du temps de transfert, et au piégeage de charges par les états d'interface dont l'effet est négligeable en hautes fréquences. Le but de cet article est de montrer l'influence des états d'interface et de la température sur l'inefficacité de transfert. Pour cela nous avons résolu l'équation différentielle non linéaire qui décrit le transfert de charge d'un puits à un autre en introduisant le champ self-induit, le champ de bord, la diffusion thermique et le phénomène de recombinaison-génération au niveau de la surface décrit par

  11. Ultrathin Au film on polymer surface for surface plasmon polariton waveguide application

    Science.gov (United States)

    Liu, Tong; Ji, Lanting; He, Guobing; Sun, Xiaoqiang; Wang, Fei; Zhang, Daming

    2017-11-01

    Formation of laterally continuous ultrathin gold films on polymer substrates is a technological challenge. In this work, the vacuum thermal evaporation method is adopted to form continuous Au films in the thickness range of 7-17 nm on polymers of Poly(methyl-methacrylate-glycidly-methacrylate) and SU-8 film surface without using the adhesion or metallic seeding layers. Absorption spectrum, scanning electron microscope and atomic force microscope images are used to characterize the Au film thickness, roughness and optical loss. The result shows that molecular-scale structure, surface energy and electronegativity have impacts on the Au film morphology on polymers. Wet chemical etching is used to fabricate 7-nm thick Au stripes embedded in polymer claddings. These long-range surface plasmon polariton waveguides demonstrate the favorable morphological configurations and cross-sectional states. Through the end-fire excitation method, propagation losses of 6-μm wide Au stripes are compared to theoretical values and analyzed from practical film status. The smooth, patternable gold films on polymer provide potential applications to plasmonic waveguides, biosensing, metamaterials and optical antennas.

  12. Evaluation de l'efficacité vis-à-vis du ruissellement de surface et des transferts latéraux dans le sol de différentes options de gestion utilisant (ou non) un couvert enherbé : Application en vue de limiter la contamination des eaux par les pesticides dans le contexte du Beaujolais viticole de coteaux

    OpenAIRE

    Gouy, V.; Peyrard, X.; Liger, L.

    2015-01-01

    / Cette étude apporte des éléments de réponse aux questions suivantes dans le contexte du Nord Beaujolais : - dans quelle mesure une zone tampon enherbée rivulaire recevant un ruissellement concentré de surface est-elle capable de réduire significativement le transfert des pesticides associés sans engendrer une contamination de nappe sous-jacente ? - dans quelle mesure une infiltration en amont en parcelle de vigne peut-elle contribuer à l'atténuation des transferts de pesticides ou engendrer...

  13. Vieillissement et développement - comptes de transfert nationaux ...

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

    Ce projet fera fond sur une phase précédente, Transferts intergénérationnels, vieillissement de la population et protection sociale en Amérique latine (no 104231) et comportera deux volets. Le premier, sous la direction de la Commission économique pour l'Amérique latine et les Caraïbes (CEPALC), vise à consolider le ...

  14. Transfert thermique à travers une interface de contact intermittent en ...

    African Journals Online (AJOL)

    Transfert thermique à travers une interface de contact intermittent en régime périodique établi. ... Mots clés: modélisation; conduction; contact intermittent; pseudo résistance de contact; résistance de contact; couplage de matériaux. In this paper, we present one-dimensional model to describe the thermal transfer through an ...

  15. Transfert de responsabilités (2009) | CRDI - Centre de recherches ...

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

    25 avr. 2016 ... ... des principes directeurs susceptibles d'orienter les pratiques en matière de transfert de responsabilité. Évaluation du transfert de la responsabilité des secrétariats internationaux du Centre de recherches pour le développement international par Jim Armstrong et Alexa Khan The Governance Network ...

  16. Application of a radiant heat transfer model to complex industrial reactive flows: combustion chambers, electric arcs; Application d`un modele de transfert radiatif a des ecoulements reactifs industriels complexes: chambres de combustion, arcs electriques

    Energy Technology Data Exchange (ETDEWEB)

    Mechitoua, N.; Dalsecco, S.; Delalondre, C.; Simonin, O. [Electricite de France (EDF), 78 - Chatou (France). Lab. National d`Hydraulique

    1996-12-31

    The direction of studies and researches (DER) of Electricite de France (EdF) has been involved for several years in a research program on turbulent reactive flows. The objectives of this program concern: the reduction of pollutant emissions from existing fossil-fueled power plants, the study of new production means (fluidized beds), and the promotion of electric power applications in the industry. An important part of this program is devoted to the development and validation of 3-D softwares and to the modeling of physical phenomena. This paper presents some industrial applications (furnaces, boilers, electric arcs) for which radiant heat transfers play an important role and the radiation models used. (J.S.) 8 refs.

  17. Colloidal Au-enhanced surface plasmon resonance imaging: application in a DNA hybridization process

    International Nuclear Information System (INIS)

    Manera, M G; Spadavecchia, J; Taurino, A; Rella, R

    2010-01-01

    The detection of the DNA hybridization mechanism using monodispersed gold nanoparticles as labels is an interesting alternative to increase the sensitivity of the SPR imaging technique. DNA-modified Au nanoparticles (DNA-Au NPs) containing single-stranded (ss) portions of DNA were prepared by monitoring their monolayer formation by UV–vis spectroscopy. The hybridization process between specific thio-oligonucleotides immobilized on the DNA–Au NPs and the corresponding complementary strands is reported and compared with the traditional hybridization process on properly self-assembled thin gold films deposited on glass substrates. A remarkable signal amplification is observed, following the incorporation of colloidal Au into a SPR biosensing experiment, resulting in an increased SPR response to DNA–DNA interactions. In particular Fusarium thiolated DNA (5'HS poly(T) 15 ATC CCT CAA AAA CTG CCG CT-3) and trichothecenes complementary DNA (5'-AGC GGC AGT TTT TGA GGG AT-3') sequences have been explored due to their possible application to agro-industry for the control of food quality

  18. Homogenization of some radiative heat transfer models: application to gas-cooled reactor cores; Homogeneisation de modeles de transferts thermiques et radiatifs: application au coeur des reacteurs a caloporteur gaz

    Energy Technology Data Exchange (ETDEWEB)

    El Ganaoui, K

    2006-09-15

    In the context of homogenization theory we treat some heat transfer problems involving unusual (according to the homogenization) boundary conditions. These problems are defined in a solid periodic perforated domain where two scales (macroscopic and microscopic) are to be taken into account and describe heat transfer by conduction in the solid and by radiation on the wall of each hole. Two kinds of radiation are considered: radiation in an infinite medium (non-linear problem) and radiation in cavity with grey-diffuse walls (non-linear and non-local problem). The derived homogenized models are conduction problems with an effective conductivity which depend on the considered radiation. Thus we introduce a framework (homogenization and validation) based on mathematical justification using the two-scale convergence method and numerical validation by simulations using the computer code CAST3M. This study, performed for gas cooled reactors cores, can be extended to other perforated domains involving the considered heat transfer phenomena. (author)

  19. Impact of cementitious materials decalcification on transfer properties: application to radioactive waste deep repository; Influence de la decalcification de materiaux cimentaires sur les proprietes de transfert: application au stockage profond de dechets radioactifs

    Energy Technology Data Exchange (ETDEWEB)

    Perlot, C

    2005-09-15

    Cementitious materials have been selected to compose the engineering barrier system (EBS) of the French radioactive waste deep repository, because of concrete physico-chemical properties: the hydrates of the cementitious matrix and the pH of the pore solution contribute to radionuclides retention; furthermore the compactness of these materials limits elements transport. The confinement capacity of the system has to be assessed while a period at least equivalent to waste activity (up to 100.000 years). His durability was sustained by the evolution of transfer properties in accordance with cementitious materials decalcification, alteration that expresses structure long-term behavior. Then, two degradation modes were carried out, taking into account the different physical and chemical solicitations imposed by the host formation. The first mode, a static one, was an accelerated decalcification test using nitrate ammonium solution. It replicates the EBS alteration dues to underground water. Degradation kinetic was estimated by the amount of calcium leached and the measurement of the calcium hydroxide dissolution front. To evaluate the decalcification impact, samples were characterized before and after degradation in term of microstructure (porosity, pores size distribution) and of transfer properties (diffusivity, gas and water permeability). The influence of cement nature (ordinary Portland cement, blended cement) and aggregates type (lime or siliceous) was observed: experiments were repeated on different mortars mixes. On this occasion, an essential reflection on this test metrology was led. The second mode, a dynamical degradation, was performed with an environmental permeameter. It recreates the EBS solicitations ensured during the re-saturation period, distinguished by the hydraulic pressure imposed by the geologic layer and the waste exothermicity. This apparatus, based on triaxial cell functioning, allows applying on samples pressure drop between 2 and 10 MPa and temperature from 20 to 80 C. Water permeability evolution relating to experimental parameters, uncoupled or coupled, was relied to mortars microstructural modifications. (author)

  20. Transfert de chaleur par convection naturelle dans une cavité rectangulaire isotherme ouverte sur une face

    OpenAIRE

    Penot, F.

    1980-01-01

    L'étude présentée ici concerne la modélisation par le calcul numérique des écoulements de convection naturelle qui se développent au sein d'une cavité rectangulaire, chauffée à température constante et ouverte sur une de ses faces. Pour différents nombres de Grashof (< 107), on calcule les nombres de Nusselt locaux et globaux de la cavité et les résultats sont confrontés à ceux de la plaque plane verticale mettant en évidence un effet de cavité sur le transfert convectif de chaleur. En outre ...

  1. Modeling of the thermal transfer inside a porous environment: application to nuclear reactors in accident situation; Modelisation du transfert thermique dans un milieu poreux: application aux reacteurs nucleaires en situation accidentelle

    Energy Technology Data Exchange (ETDEWEB)

    Rubiolo, P.R

    2000-03-01

    The purpose of this report is to simulate heat exchanges occurring by conduction, by convection and by radiating in a porous medium made up of opaque particles in a semi-transparent fluid. Usually the determination of the macroscopic equations is based on homogenization techniques, but in the case of a major accident, the complexity of the problem is so overwhelming that semi-empirical methods are used to determine macroscopic coefficients. The author develops a new method to determine these coefficients, this method is based on the calculation of different tensors: the equivalent conductivity tensor, the radiative conductivity tensor, the thermal conductivity tensor and the heat exchange coefficient (h{sub sf}) between the solid phase and the fluid one. The first chapter briefly describes energy, impulse and mass balances. In the case of the energy balance the solid phase is not supposed to be in thermal equilibrium with the liquid phase. The second chapter presents an application of the porous media method to a one-dimensional and stationary problem, this application to a simple problem gives an idea of the performance of the method. The model allowing the calculation of h{sub sf} is developed, it is a wide range model. The second chapter ends with the presentation of the model allowing the computing of the effective conductivity of fuel rods. A comparison between results given by this new method and other numeric calculations or experimental data coming from benchmarks is presented in the third chapter. This chapter ends with the simulation of a reactor core in accidental situation, 2 cases are presented: with and without the presence of water steam. (A.C.)

  2. Properties of ordered titanium templates covered with Au thin films for SERS applications

    Energy Technology Data Exchange (ETDEWEB)

    Grochowska, Katarzyna, E-mail: kgrochowska@imp.gda.pl [Centre for Plasma and Laser Engineering, Szewalski Institute of Fluid-Flow Machinery, Polish Academy of Sciences, Fiszera 14 St., 80-231 Gdańsk (Poland); Siuzdak, Katarzyna [Centre for Plasma and Laser Engineering, Szewalski Institute of Fluid-Flow Machinery, Polish Academy of Sciences, Fiszera 14 St., 80-231 Gdańsk (Poland); Sokołowski, Michał; Karczewski, Jakub [Faculty of Applied Physics and Mathematics, Gdańsk University of Technology, Narutowicza 11/12 St., 80-233 Gdańsk (Poland); Szkoda, Mariusz [Centre for Plasma and Laser Engineering, Szewalski Institute of Fluid-Flow Machinery, Polish Academy of Sciences, Fiszera 14 St., 80-231 Gdańsk (Poland); Faculty of Chemistry, Gdańsk University of Technology, Narutowicza 11/12 St., 80-233 Gdańsk (Poland); Śliwiński, Gerard [Centre for Plasma and Laser Engineering, Szewalski Institute of Fluid-Flow Machinery, Polish Academy of Sciences, Fiszera 14 St., 80-231 Gdańsk (Poland)

    2016-12-01

    Graphical abstract: - Highlights: • Dimpled Ti substrates prepared via anodization followed by etching. • Highly ordered nano-patterned titanium templates covered with thin Au films. • Enhanced Raman signal indicates on promising sensing material. - Abstract: Currently, roughened metal nanostructures are widely studied as highly sensitive Raman scattering substrates that show application potential in biochemistry, food safety or medical diagnostic. In this work the structural properties and the enhancement effect due to surface enhanced Raman scattering (SERS) of highly ordered nano-patterned titanium templates covered with thin (5–20 nm) gold films are reported. The templates are formed by preparation of a dense structure of TiO{sub 2} nanotubes on a flat Ti surface (2 × 2 cm{sup 2}) and their subsequent etching down to the substrate. SEM images reveal the formation of honeycomb nanostructures with the cavity diameter of 80 nm. Due to the strongly inhomogeneous distribution of the electromagnetic field in the vicinity of the Au film discontinuities the measured average enhancement factor (10{sup 7}–10{sup 8}) is markedly higher than observed for bare Ti templates. The enhancement factor and Raman signal intensity can be optimized by adjusting the process conditions and thickness of the deposited Au layer. Results confirm that the obtained structures can be used in surface enhanced sensing.

  3. Pratiques d'élevage avicole au Sud-Bénin (Afrique de l'Ouest) et ...

    African Journals Online (AJOL)

    'introduction de germes pathogènes dans les élevages. Or, les fumiers de volaille sont très utilisés dans le maraîchage au Bénin. Par conséquent, le transfert de germes des fumiers vers les produits maraîchers est à craindre. L'objectif de ...

  4. Shape and size controlled synthesis of Au nanorods: H2S gas-sensing characterizations and antibacterial application

    International Nuclear Information System (INIS)

    Lanh, Le Thi; Hoa, Tran Thai; Cuong, Nguyen Duc; Khieu, Dinh Quang; Quang, Duong Tuan; Van Duy, Nguyen; Hoa, Nguyen Duc; Van Hieu, Nguyen

    2015-01-01

    Highlights: • We have demonstrated a facile method to prepare colloid Au nanorods. • The size and shape of Au nanorods can be controlled via seed-mediated growth method. • The H 2 S gas-sensing properties have been investigated. • The antibacterial application has been conducted. - Abstract: Controlling their size and shape is one of the important issues in the fundamental study and application of colloidal metal nanoparticles. In the current study, different sizes and shapes of Au nanorods were fabricated using a seed-mediated growth method. Material characterization by X-ray diffraction and transmission electron microscopy revealed that the obtained products were made of single-crystal Au nanorods with an average diameter and length of 10 nm and 40 nm, respectively. The Au nanorod-based sensor exhibited significantly high sensitivity and fast response/recovery time to low concentrations (2.5–10 ppm) of H 2 S at temperatures ranging from 300 °C to 400 °C. Additionally, they exhibited antibacterial effect at low concentration. These results suggested that the fabricated Au nanorods have excellent potential for practical application in air pollution monitoring and biomedicine

  5. Shape and size controlled synthesis of Au nanorods: H{sub 2}S gas-sensing characterizations and antibacterial application

    Energy Technology Data Exchange (ETDEWEB)

    Lanh, Le Thi [College of Sciences, Hue University, 77 Nguyen Hue, Hue City (Viet Nam); Hoa, Tran Thai, E-mail: trthaihoa@yahoo.com [College of Sciences, Hue University, 77 Nguyen Hue, Hue City (Viet Nam); Cuong, Nguyen Duc [College of Sciences, Hue University, 77 Nguyen Hue, Hue City (Viet Nam); Faculty of Hospitality and Tourism, Hue University, 22 Lam Hoang, Hue City (Viet Nam); Khieu, Dinh Quang [College of Sciences, Hue University, 77 Nguyen Hue, Hue City (Viet Nam); Quang, Duong Tuan [College of Education, Hue University, 34 Le Loi, Hue City (Viet Nam); Van Duy, Nguyen; Hoa, Nguyen Duc [International Training Institute for Materials Science, Hanoi University of Science and Technology, Hanoi (Viet Nam); Van Hieu, Nguyen, E-mail: hieu@itims.edu.vn [International Training Institute for Materials Science, Hanoi University of Science and Technology, Hanoi (Viet Nam)

    2015-06-25

    Highlights: • We have demonstrated a facile method to prepare colloid Au nanorods. • The size and shape of Au nanorods can be controlled via seed-mediated growth method. • The H{sub 2}S gas-sensing properties have been investigated. • The antibacterial application has been conducted. - Abstract: Controlling their size and shape is one of the important issues in the fundamental study and application of colloidal metal nanoparticles. In the current study, different sizes and shapes of Au nanorods were fabricated using a seed-mediated growth method. Material characterization by X-ray diffraction and transmission electron microscopy revealed that the obtained products were made of single-crystal Au nanorods with an average diameter and length of 10 nm and 40 nm, respectively. The Au nanorod-based sensor exhibited significantly high sensitivity and fast response/recovery time to low concentrations (2.5–10 ppm) of H{sub 2}S at temperatures ranging from 300 °C to 400 °C. Additionally, they exhibited antibacterial effect at low concentration. These results suggested that the fabricated Au nanorods have excellent potential for practical application in air pollution monitoring and biomedicine.

  6. Détermination du temps de résidence des eaux souterraines : application au transfert d'azote dans les aquifères fracturés hétérogènes

    OpenAIRE

    Ayraud , Virginie

    2005-01-01

    Heterogeneous fractured aquifers are extensively developed in crystalline rocks, such as schistor granite. In these aquifers, porosity ranges from the fractures to the microporosity containedin pores and fissures of the matrix. A better characterisation of such aquifers and especiallyadapted to search for new water reservoir in Brittany, was undertaken through: (1) temporalchronicles, isotopic analyses and laboratory experiments and (2) by the interpretation ofresidence times through CFC anal...

  7. Modélisation dynamique des transferts de chaleur au sein d'un récepteur linéaire de Fresnel : application d'une régulation lors de passages nuageux

    OpenAIRE

    Tapaches , Emeric; Castaing-Lasvignottes , Jean; Lucas , Franck; Bezian , Jean-Jacques; Veynandt , François; Pons , Michel

    2014-01-01

    ISBN 978-2-37111-003-8ISSN 1258-164X; National audience; L’utilisation des concentrateurs solaires linéaires de Fresnel pour la production d’électricité par centrale thermodynamique est une solution de plus en plus attractive. Néanmoins, le comportement dynamique et les bonnes stratégies de contrôle pour cette technologie demandent encore à être étudiées. Cet article présente le développement d’un modèle dynamique de ce capteur couplant : 1/ un code simulant la concentration optique ; 2/ un c...

  8. Synergie expérimentale impliquant la mesure lidar pour la caractérisation optique et microphysique de l'aérosol : applications à la qualité de l'air et au transfert radiatif.

    OpenAIRE

    Raut , Jean-Christophe

    2008-01-01

    The work carried out in this study is devoted to a better understanding of the evolution of aerosol physical, chemical and optical properties for urban pollution aerosols, dust and biomass burning particles. It mainly concerns the complex refractive index and the single-scattering albedo. Such a characterisation is indeed necessary so as to fulfil the requirements of scientific and societal air quality and global climate evolution questions. Our study is based on a synergy between different m...

  9. Self-standing corrugated Ag and Au-nanorods for plasmonic applications

    DEFF Research Database (Denmark)

    Habouti, S.; Mátéfi-Tempfli, M.; Solterbeck, C.-H.

    2011-01-01

    We use home-made Si-supported anodized alumina thin film templates for the electrodeposition of large area self-standing Ag- and Au-nanorod (Au-NR) arrays. The deposition conditions chosen, i.e. electrolyte composition and deposition voltage, lead to a corrugated rod morphology, particularly for Au...

  10. Dimensions du transfert adolescent et indications thérapeutiques

    Directory of Open Access Journals (Sweden)

    Laetitia Petit

    2011-12-01

    Full Text Available Nous proposons de confronter les indications thérapeutiques de dispositifs psychanalytiques durant la période adolescente - psychanalyse, psychothérapie psychanalytique, psychodrame analytique individuel. Les dispositifs psychanalytiques constituent une des possibilités d'indication, limitée par la prévalence du maniement du transfert quand la crise d'adolescence est un moment ordinaire de labilité des manifestations pathologiques de révision des états de la structure. Les entretiens préliminaires sont alors fondamentaux pour évaluer cette indication qui sera décisive, mais qui reste néanmoins temporellement dépendante de l'engagement transférentiel de l'adolescent.

  11. Virus recombinant associés à l'adénovirus : développement des procédés et application du transfert de gène pour la dystrophie musculaire

    OpenAIRE

    Dias Florencio Leite, Gabriella

    2017-01-01

    The interest of recombinant Adeno-Associated Virus (rAAV) vectors for research and clinical purposes in the treatment of genetic diseases have led to the rapid evolution of methods for AAV production in the last two decades (Ayuso et al., 2010). Their broad in vivo biodistribution and long-term efficacy in postmitotic tissues make them good candidates for numerous gene transfer applications. In addition, the specificity of the treatment can be increased when the right serotype is chosen to ta...

  12. Electrical conductivity dependence of thin metallic films of Au and Pd as a top electrode in capacitor applications

    International Nuclear Information System (INIS)

    Nazarpour, S.; Langenberg, E.; Jambois, O.; Ferrater, C.; Garcia-Cuenca, M.V.; Polo, M.C.; Varela, M.

    2009-01-01

    Electrical conductivity dependence of thin metallic films of Au and Pd over the different perovskites was investigated. It is found from electrical properties that crystallographic growth orientation of Au and Pd thin layers attained from X-ray diffraction results indicate the slop of current (I)-voltage (V) plots. Besides, surface morphology and topography was considered using Field Emission Scanning Electron Microscopy and Atomic Force Microscopy, respectively. Obtained results showed the Stranski-Krastanov growth of the Pd and Au. Indeed, diminishing of the root-mean-square roughness of Pd/BiMnO 3 /SrTiO 3 following by Au deposition should be concerned due to growth of Au onto the crack-like parts of the substrate. These crack-like parts appeared due to parasitic phases of the Bi-Mn-O system mainly Mn 3 O 4 (l 0 l) and Mn 3 O 4 (0 0 4 l). The different response in the electrical properties of heterostructures suggests that electrical conductance of the Au and Pd thin metallic films have the crystallographic orientation dependence. Furthermore, polycrystallinity of the thin metallic films are desired in electrode applications due to increase the conductivity of the metallic layers.

  13. Technical Evaluation Report on Knowledge Based System Applications for Guidance and Control (Application des Systemes a Base de Connaissances au Guidage-Pilotage),

    Science.gov (United States)

    1991-07-01

    Sanz-Aranguez SP ProfessorJohn T.Shcpherd UK Dr Elihu Zimet us HOST PAINEL COORDINATOR Mdr Carlos A. Garriga. Lopez SENER Ingenieria y Sistemas SA...on C- Knowledge Based System Applications for Guidance and Control (Application des Syst~mes ’ Base de Connaissances au Guidage-Pilotage) -¢ NORTH...for ’ 3tt’--. f Guidance and Control (Application des Syst~mes a Base de Connaissances DJie au Guidage-Pilotage) Dr Franco Canepa ALENIA Gruppo Aerei

  14. Formation of Au nanoparticles on CNTs three dimensional structure for LSPR biosensor application

    Science.gov (United States)

    Yang, Ming; Shimizu, Tetsuhide

    2017-02-01

    A 3D LSPR sensor was fabricated by using CNTs as support and depositing AuNPs on the support in this study. We proposed a simple process to arrange AuNPs to CNTs by using vacuum deposition and annealing for 3D LSPR sensor. In order to fabricate 3D LSPR sensor, CNTs was synthesized and patterned on quartz glass substrate by CVD method and photolithography. For the synthesis of AuNPs, Au thin film was deposited on glass and CNTs by vacuum deposition. After deposition, Au thin film on glass and CNTs was particulated by annealing. The performance of 3D LSPR sensor was confirmed using BSA for bio analysis. LSPR characteristics was measured and compared before and after adsorption of BSA. The detection limit was 100ng/ml and detection sensitivity was 10 times in comparison with 2D LSPR sensor of same AuNPs formation condition.

  15. Synthesis of biocompatible AuAgS/Ag2S nanoclusters and their applications in photocatalysis and mercury detection

    International Nuclear Information System (INIS)

    Zhao, Qian; Chen, Shenna; Zhang, Lingyang; Huang, Haowen; Liu, Fengping; Liu, Xuanyong

    2014-01-01

    In this paper, a facile approach for preparation of AuAgS/Ag 2 S nanoclusters was developed. The unique AuAgS/Ag 2 S nanoclusters capped with biomolecules exhibit interesting excellent optical and catalytic properties. The fluorescent AuAgS/Ag 2 S nanoclusters show tunable luminescence depending on the nanocluster size. The apoptosis assay demonstrated that the AuAgS/Ag 2 S nanoclusters showed low cytotoxicity and good biocompatibility. Therefore, the nanoclusters can be used not only as a probe for labeling cells but also for their photocatalytic activity for photodegradation of organic dye. Moreover, a highly selective and sensitive assay for detection of mercury including Hg 2+ and undissociated mercury complexes was developed based on the quenching fluorescent AuAgS/Ag 2 S nanoclusters, which provides a promising approach for determining various forms of Hg in the mercury-based compounds in environment. These unique nanoclusters may have potential applications in biological labeling, sensing mercury, and photodegradation of various organic pollutants in waste water.Graphical Abstract

  16. Synthesis and characterization of Au-MWCNT/PEDOT: PSS composite film for optoelectronic applications

    Science.gov (United States)

    Jasna, M.; Anjana, R.; Jayaraj, M. K.

    2017-08-01

    Recently, flexible organic optoelectronics have got great attention because of their light weight, mechanical flexibility and cost effective fabrication process. Conjugated polymers like PEDOT: PSS are widely used for the transparent electrode applications due to its chemical stability, high conductivity, flexibility and optical transparency in the visible region. Conductivity of the PEDOT: PSS polymer can be enhanced by adding organic solvents or conducting nano fillers like CNT, graphene, etc. Carbon nanotubes are good nano fillers to enhance the conductivity and mechanical strength of PEDOT: PSS composite film. Inthe present work, the effect of gold nano particles in PEDOT: PSS/CNT composite is studied. The conductivity enhancement in PEDOT: PSS/CNT thin films can be attributed to the formation of CNT network in the polymer matrix and conformational change of the PEDOT from benzoid to quinoid structure. Even though the conductivity was enhanced, the transparency of the composite thin films decreased with increase in CNT concentration. To overcome this problem, gold nano particles were attached to CNT walls via chemical route. AuMWCNT/PEDOT: PSS composite films were prepared by spin coating method. TEM images confirmed the decoration of gold nano particles on CNT walls. Electrical and optical properties of the composite films were studied. This simple solution processed conducting films are suitable for optoelectronic applications

  17. Euromet action 428: transfer of ge detectors efficiency calibration from point source geometry to other geometries; Action euromet 428: transfert de l'etalonnage en rendement de detecteurs au germanium pour une source ponctuelle vers d'autres geometries

    Energy Technology Data Exchange (ETDEWEB)

    Lepy, M.Ch

    2000-07-01

    The EUROMET project 428 examines efficiency transfer computation for Ge gamma-ray spectrometers when the efficiency is known for a reference point source geometry in the 60 keV to 2 MeV energy range. For this, different methods are used, such as Monte Carlo simulation or semi-empirical computation. The exercise compares the application of these methods to the same selected experimental cases to determine the usage limitations versus the requested accuracy. For carefully examining these results and trying to derive information for improving the computation codes, this study was limited to a few simple cases, from an experimental efficiency calibration for point source at 10-cm source-to-detector distance. The first part concerns the simplest case of geometry transfer, i.e., using point sources for 3 source-to-detector distances: 2,5 and 20 cm; the second part deals with transfer from point source geometry to cylindrical geometry with three different matrices. The general results show that the deviations between the computed results and the measured efficiencies are for the most part within 10%. The quality of the results is rather inhomogeneous and shows that these codes cannot be used directly for metrological purposes. However, most of them are operational for routine measurements when efficiency uncertainties of 5-10% can be sufficient. (author)

  18. AuCu@Pt Nanoalloys for Catalytic Application in Reduction of 4-Nitrophenol

    Directory of Open Access Journals (Sweden)

    Sadia Mehmood

    2016-01-01

    Full Text Available To enhance and optimize nanocatalyst ability for nitrophenol (4-NP reduction reaction we look beyond Au-metal nanoparticles and describe a new class of Au nanoalloys with controlled composition for core of AuCu-metals and Pt-metal shell. The reduction of 4-NP was investigated in aqueous media spectroscopically on 7.8 nm Au nanospheres (AuNSs, 8.3 nm AuCuNSs, and 9.1 nm AuCu@Pt core-shell NSs in diameter. The rate constants of the catalyzed reaction at room temperature, activation energies, and entropies of activation of reactions catalyzed by the AuCu@Pt core-shell NSs are found to have different values to those of the pure metal NSs. The results strongly support the proposal that catalysis by nanoparticles is taking place efficiently on the surface of NSs. These core-shell nanocatalysts exhibited stability throughout the reduction reaction and proved that heterogonous type mechanisms are most likely to be dominant in nanoalloy based catalysis if the surface of the NSs is not defected upon shell incorporation.

  19. Prix de transfert optimaux et comportement stratégique des multinationales

    OpenAIRE

    Thierry MADIES

    2004-01-01

    L'objet de cet article est de proposer un modèle permettant de déterminer le prix de transfert optimal entre deux filiales d'une multinationale qui choisissent de façon décentralisée les quantités (concurrence à la Cournot) ou les prix optimaux (concurrence à la Bertrand) sur les marchés oligopolistiques où elles opèrent. Nous montrons que le prix de transfert qui permet à la multinationale de maximiser ses bénéfices consolidés est fonction de trois effets : (1) un effet « transfert de bénéfi...

  20. Etude du transfert thermique entre un jet rond turbulent et une paroi ...

    African Journals Online (AJOL)

    Dans ce travail, on s\\'intéresse à l\\'étude du transfert de chaleur d\\'une plaque plane soumise à l\\'action d\\'un jet d\\'air perpendiculaire. L\\'étude de la possibilité d\\'améliorer le transfert de chaleur est effectuée en fonction des paramètres caractéristiques de l\\'interaction jet - paroi. Le problème du jet rond turbulent frappant ...

  1. Application of Turkevich Method for Gold Nanoparticles Synthesis to Fabrication of SiO2@Au and TiO2@Au Core-Shell Nanostructures

    Science.gov (United States)

    Dobrowolska, Paulina; Krajewska, Aleksandra; Gajda-Rączka, Magdalena; Bartosewicz, Bartosz; Nyga, Piotr; Jankiewicz, Bartłomiej J.

    2015-01-01

    The Turkevich synthesis method of Au nanoparticles (AuNPs) was adopted for direct fabrication of SiO2@Au and TiO2@Au core-shell nanostructures. In this method, chloroauric acid was reduced with trisodium citrate in the presence of amine-functionalized silica or titania submicroparticles. Core-shells obtained in this way were compared to structures fabricated by mixing of Turkevich AuNPs with amine-functionalized silica or titania submicroparticles. It was found that by modification of reaction conditions of the first method, such as temperature and concentration of reagents, control over gold coverage on silicon dioxide particles has been achieved. Described method under certain conditions allows fabrication of semicontinuous gold films on the surface of silicon dioxide particles. To the best of our knowledge, this is the first report describing use of Turkevich method to direct fabrication of TiO2@Au core-shell nanostructures.

  2. Facile Synthesis of Quasi-One-Dimensional Au/PtAu Heterojunction Nanotubes and Their Application as Catalysts in an Oxygen-Reduction Reaction.

    Science.gov (United States)

    Cai, Kai; Liu, Jiawei; Zhang, Huan; Huang, Zhao; Lu, Zhicheng; Foda, Mohamed F; Li, Tingting; Han, Heyou

    2015-05-11

    An intermediate-template-directed method has been developed for the synthesis of quasi-one-dimensional Au/PtAu heterojunction nanotubes by the heterogeneous nucleation and growth of Au on Te/Pt core-shell nanostructures in aqueous solution. The synthesized porous Au/PtAu bimetallic nanotubes (PABNTs) consist of porous tubular framework and attached Au nanoparticles (AuNPs). The reaction intermediates played an important role in the preparation, which fabricated the framework and provided a localized reducing agent for the reduction of the Au and Pt precursors. The Pt7 Au PABNTs showed higher electrocatalytic activity and durability in the oxygen-reduction reaction (ORR) in 0.1 M HClO4 than porous Pt nanotubes (PtNTs) and commercially available Pt/C. The mass activity of PABNTs was 218 % that of commercial Pt/C after an accelerated durability test. This study demonstrates the potential of PABNTs as highly efficient electrocatalysts. In addition, this method provides a facile strategy for the synthesis of desirable hetero-nanostructures with controlled size and shape by utilizing an intermediate template. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  3. Transferts thermiques dans les bassins sédimentaires Heat Transfers in Sedimentary Basins

    Directory of Open Access Journals (Sweden)

    Perrin J. F.

    2006-11-01

    Full Text Available La connaissance de l'évolution des températures dans les bassins sédimentaires est un instrument utile pour l'exploration pétrolière. En effet, connaissant la cinétique de dégradation chimique, on peut prévoir les rendements de transformation de la matière organique dans un bassin donné. La localisation des roches mères permet ensuite d'évaluer le potentiel pétrolier d'un bassin. L'étude présentée ici traite d'un modèle numérique destiné à prévoir ces champs de température tout au long de l'histoire d'un bassin, le modèle servant aussi pour l'étude des phénomènes de dog-leg thermique. Le modèle prend en compte les transferts par conduction et convection forcée (écoulement de l'eau de compaction et calcule un état des pressions et porosités. II fournit des résultats conformes aux valeurs observées in situ, et permet d'expliquer les anomalies de pressions. Knowing how temperatures have evolved in sedimentary basins is of great importance for petroleum exploration. If the chemical degradation kinetics is known, the transformation yields of organic matter can be forecast in a given basin. Then the location of source rocks can be used to evaluate the petroleum potential of a basin. This article describes a numerical model designed to determine these temperature ranges during the entire history of a basin. The model can also be used to investigate thermal dog-leg phenomena. It takes transfers by conduction and forced convection into consideration (flow of compaction water and calculates pressure and porosity conditions. The results it gives are in good agreement with values observed in situ so that various pressure anomalies can be explained.

  4. Corrosion Protection of Al/Au/ZnO Anode for Hybrid Cell Application.

    Science.gov (United States)

    Slaughter, Gymama; Stevens, Brian

    2015-11-16

    Effective protection of power sources from corrosion is critical in the development of abiotic fuel cells, biofuel cells, hybrid cells and biobateries for implantable bioelectronics. Corrosion of these bioelectronic devices result in device inability to generate bioelectricity. In this paper Al/Au/ZnO was considered as a possible anodic substrate for the development of a hybrid cell. The protective abilities of corrosive resistant aluminum hydroxide and zinc phosphite composite films formed on the surface of Al/Au/ZnO anode in various electrolyte environments were examined by electrochemical methods. The presence of phosphate buffer and physiological saline (NaCl) buffer allows for the formation of aluminum hyrdroxide and zinc phosphite composite films on the surface of the Al/Au/ZnO anode that prevent further corrosion of the anode. The highly protective films formed on the Al/Au/ZnO anode during energy harvesting in a physiological saline environment resulted in 98.5% corrosion protective efficiency, thereby demonstrating that the formation of aluminum hydroxide and zinc phosphite composite films are effective in the prevention of anode corrosion during energy harvesting. A cell assembly consisting of the Al/Au/ZnO anode and platinum cathode resulted in an open circuit voltage of 1.03 V. A maximum power density of 955.3 mW/ cm² in physiological saline buffer at a cell voltage and current density of 345 mV and 2.89 mA/ cm², respectively.

  5. Binary self-assembled monolayers modified Au nanoparticles as carriers in biological applications.

    Science.gov (United States)

    Chang, Hsun-Yun; You, Yun-Wen; Liao, Hua-Yang; Shyue, Jing-Jong

    2014-12-01

    Gold nanoparticles (AuNPs) are good nonviral carriers because of their ease of synthesis and conjugation in biochemistry, and self-assembled monolayers (SAMs) provide a tunable system to change their interfacial properties. Using homogeneously mixed carboxylic acid and amine functional groups, a series of surface potentials and isoelectric points (IEPs) could be obtained and allow systematic study of the effect of surface potential. In this work, the result of the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay revealed that binary-SAM modified AuNPs have high biocompatibility with HEK293T cells. The amount of AuNPs ingested by the cells was found to increase with increasing surface potential and the difference was also confirmed with a scanning transmission electron microscope. The ability of binary-SAM modified AuNPs as carriers was examined, and the plasmid deoxyribose nucleic acid (DNA)-containing eGFP reporter gene was used as the model cargo. Fluorescence imaging revealed that the transfection efficiency generally increased with increasing surface potential. More importantly, when the IEP of the AuNPs was higher than that of the environment of the endosome but lower than that of the cytoplasm, the plasmid DNA can be protected better and released more easily during the endocytosis process hence higher efficiency is obtained with 60% NH2 and 40% COOH in the binary-SAM.

  6. Synthesis of Au Nanostars and Their Application as Surface Enhanced Raman Scattering-Activity Tags Inside Living Cells.

    Science.gov (United States)

    Cao, Xiaowei; Shi, Chaowen; Lu, Wenbo; Zhao, Hang; Wang, Man; Tong, Wei; Dong, Jian; Han, Xiaodong; Qian, Weiping

    2015-07-01

    This work presents the synthesis and characterization of Au nanostars (AuNSs) and demonstrates their application as surface enhanced Raman scattering (SERS)-activity tags for cellular imaging and sensing. Nile blue A (NBA) and bovine serum albumin (BSA) were used as Raman reporter molecules and capping materials, respectively. The SERS-activity tags were tested on human lung adenocarcinoma cell (A549) and alveolar type II cell (AT II) and found to present a low level of cytotoxicity and high chemical stability. These SERS-activity tags not only can be applied in multiplexed cellular imaging, including dark field imaging, transmission electron microscopy (TEM) and SERS imaging, but also can be used for cellular sensing. The SERS spectra clearly identified cellular important components such as proteins, nucleic acids, lipids, and carbohydrates. This study also shows that endocytosis is the main channel of tags internalized in cells. The AuNSs exhibiting strong surface enhanced Raman effects are utilized in the design of an efficient, stable SERS-activity tag for intracellular applications.

  7. Production of radio-gold {sup 199}Au for diagnostic and therapeutic applications

    Energy Technology Data Exchange (ETDEWEB)

    Khandaker, Mayeen Uddin, E-mail: mu-khandaker@um.edu.my; Kassim, Hasan Abu, E-mail: hasanak@um.edu.my [Department of Physics, University of Malaya, 50603 Kuala Lumpur (Malaysia); Haba, Hiromitsu, E-mail: haba@riken.jp [Nishina Center for Accelerator-Based Science, RIKEN, Wako, Saitama 351-0198 (Japan)

    2016-01-22

    Production cross-sections of the {sup nat}Pt(d,x){sup 199}Au reactions have been measured from a 24-MeV deuteron energy down to the threshold by using a stacked-foil activation technique combined with HPGe γ-ray spectrometry. Only a partial agreement is obtained with the existing literature data. Theoretical data extracted from the TENDL-2013 library shows large discrepancy with the measured ones. Physical thick target yield for the {sup 199}Au radionuclide was deduced using the measured cross-sections, and found a general agreement with the directly measured yield available in the literature. This study reveals that a low deuteron energy (<15 MeV) cyclotron and an enriched {sup 198}Pt (100%) target could be used to obtain {sup 199}Au in no carrier added form.

  8. Characterization of self-assembled electrodes based on Au-Pt nanoparticles for PEMFC application

    Energy Technology Data Exchange (ETDEWEB)

    Valenzuela, E. [Politecnica Univ. de Chiapas, Tuxtla Gutierrez, Chiapas (Mexico). Energia y Sustentabilidad; Sebastian, P.J. [Politecnica Univ. de Chiapas, Chiapas (Mexico). Energia y Sustentabilidad; Centro de Investigacion en Energia, UNAM, Morelos (Mexico); Gamboa, S.A. [Centro de Investigacion en Energia, UNAM, Morelos (Mexico); Pal, U. [Inst. de Fisica, Universidad Autonoma de Puebla Univ., Puebla (Mexico). Inst. de Fisica; Gonzalez, I. [Autonoma Metropolitana Univ. (Mexico). Dept. de Quimica

    2008-07-01

    This paper reported on a study in which membrane electrode assemblies (MEAs) were fabricated by depositing Au, Pt and AuPt nanoparticles on Nafion 115 membrane for use in a proton exchange membrane fuel cell (PEMFC). A Rotating Disc Electrode (RDE) was used to measure the nanoparticle catalyst activity. After deposition of the nanoparticles on the membrane, the surface was studied by Scanning Electron Microscopy (SEM) and Energy Dispersive Spectroscopy (EDS). The membrane proton conduction process was studied by Electrochemical Impedance Spectroscopy (EIS) with the 4 probe technique. The MEAs fabricated with Nafion/Metal membranes were evaluated in a PEMFC under standard conditions. Colloidal solutions were used to prepare self-assembled electrodes with nanoparticles deposited on Nafion membrane. The particles deposited on Nafion showed good stability and had homogeneous distribution along the membrane surface. The impedance results revealed an increase in the membrane proton resistance of the self-assembled electrodes compared to unmodified Nafion. The Au-Pt nanoparticles were obtained by chemical reduction. The nanoparticle size in the three systems was about 2 nm. The self-assembled electrodes performed well in standard conditions. The optimum colloidal concentration and immersion time must be determined in order to obtain good catalytic activity and high membrane conductance. The self-assembled Nafion/AuPt had the best open circuit potential (887 mV). The Au and Pt self-assemblies showed a similar performance in terms of maximum power and maximum current density. The performance of the Nafion/Au self-assembly was influenced more by ohmic losses, particularly in the membrane. The maximum power generation was obtained at 0.35 V. The mass transport losses increased after this value, thereby affecting the efficiency of the PEMFC. 2 figs.

  9. Transferts culturels et passeurs de culture dans le monde du livre (France - Brésil, XIX siècle) / Cultural Transfers and Cultural Mediators of the Literary World: France and Brazil in the 19th Century

    OpenAIRE

    COOPER-RICHET, Diana

    2013-01-01

    Grâce à des concepts nouveaux, tels que ceux de transfert et de passeur, les échanges culturels entre la France et le Brésil au XIX siècle, peuvent désormais être revisités au prisme de l’histoire des imprimés. La circulation, d’un côté à l’autre de l’Atlantique, de livres et de périodiques, en français et en portugais, le rôle joué par un certain nombre de libraires-éditeurs parisiens dans la production et dans la diffusion de ces ouvrages sont révélateurs de la place occupée par Paris dans ...

  10. Simultaneous AuIII Extraction and In Situ Formation of Polymeric Membrane-Supported Au Nanoparticles: A Sustainable Process with Application in Catalysis.

    Science.gov (United States)

    Mora-Tamez, Lucía; Esquivel-Peña, Vicente; Ocampo, Ana L; Rodríguez de San Miguel, Eduardo; Grande, Daniel; de Gyves, Josefina

    2017-04-10

    A polymeric membrane-supported catalyst with immobilized gold nanoparticles (AuNPs) was prepared through the extraction and in situ reduction of Au III salts in a one-step strategy. Polymeric inclusion membranes (PIMs) and polymeric nanoporous membranes (PNMs) were tested as different membrane-support systems. Transport experiments indicated that PIMs composed of cellulose triacetate, 2-nitrophenyloctyl ether, and an aliphatic tertiary amine (Adogen 364 or Alamine 336) were the most efficient supports for Au III extraction. The simultaneous extraction and reduction processes were proven to be the result of a synergic phenomenon in which all the membrane components were involved. Scanning electron microscopy characterization of cross-sectional samples suggested a distribution of AuNPs throughout the membrane. Transmission electron microscopy characterization of the AuNPs indicated average particle sizes of 36.7 and 2.9 nm for the PIMs and PNMs, respectively. AuNPs supported on PIMs allowed for >95.4 % reduction of a 0.05 mmol L -1 4-nitrophenol aqueous solution with 10 mmol L -1 NaBH 4 solution within 25 min. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  11. Mixed Phytochemicals Mediated Synthesis of Multifunctional Ag-Au-Pd Nanoparticles for Glucose Oxidation and Antimicrobial Applications.

    Science.gov (United States)

    Rao, K Jagajjanani; Paria, Santanu

    2015-07-01

    The growing awareness toward the environment is increasing commercial demand for nanoparticles by green route syntheses. In this study, alloy-like Ag-Au-Pd trimetallic nanoparticles have been prepared by two plants extracts Aegle marmelos leaf (LE) and Syzygium aromaticum bud extracts (CE). Compositionally different Ag-Au-Pd nanoparticles with an atomic ratio of 5.26:2.16:1.0 (by LE) and 11.36:13.14:1.0 (by LE + CE) of Ag:Au:Pd were easily synthesized within 10 min at ambient conditions by changing the composition of phytochemicals. The average diameters of the nanoparticles by LE and LE + CE are ∼8 and ∼11 nm. The catalytic activity of the trimetallic nanoparticles was studied, and they were found to be efficient catalysts for the glucose oxidation process. The prepared nanoparticles also exhibited efficient antibacterial activity against a model Gram-negative bacteria Escherichia coli. The catalytic and antimicrobial properties of these readymade trimetallic nanoparticles have high possibility to be utilized in diverse fields of applications such as health care to environmental.

  12. Direct Cross-Linking of Au/Ag Alloy Nanoparticles into Monolithic Aerogels for Application in Surface-Enhanced Raman Scattering.

    Science.gov (United States)

    Gao, Xiaonan; Esteves, Richard J Alan; Nahar, Lamia; Nowaczyk, Jordan; Arachchige, Indika U

    2016-05-25

    The direct cross-linking of Au/Ag alloy nanoparticles (NPs) into high surface area, mesoporous Au/Ag aerogels via chemical oxidation of the surface ligands is reported. The precursor alloy NPs with composition-tunable morphologies were produced by galvanic replacement of the preformed Ag hollow NPs. The effect of Au:Ag molar ratio on the NP morphology and surface plasmon resonance has been thoroughly investigated and resulted in smaller Au/Ag alloy NPs (4-8 nm), larger Au/Ag alloy hollow NPs (40-45 nm), and Au/Ag alloy hollow particles decorated with smaller Au NPs (2-5 nm). The oxidative removal of surfactant ligands, followed by supercritical drying, is utilized to construct large (centimeter to millimeter) self-supported Au/Ag alloy aerogels. The resultant assemblies exhibit high surface areas (67-73 m(2)/g), extremely low densities (0.051-0.055 g/cm(3)), and interconnected mesoporous (2-50 nm) networks, making them of great interest for a number of new technologies. The influence of mesoporous gel morphology on surface-enhanced Raman scattering (SERS) has been studied using Rhodamine 101 (Rd 101) as the probe molecule. The alloy aerogels exhibit SERS signal intensities that are 10-42 times higher than those achieved from the precursor Au/Ag alloy NPs. The Au/Ag alloy aerogel III exhibits SERS sensing capability down to 1 nM level. The increased signal intensities attained for alloy aerogels are attributed to highly porous gel morphology and enhanced surface roughness that can potentially generate a large number of plasmonic hot spots, creating efficient SERS substrates for future applications.

  13. Nanostructuring of thin Au films deposited on ordered Ti templates for applications in SERS

    Science.gov (United States)

    Grochowska, Katarzyna; Siuzdak, Katarzyna; Macewicz, Łukasz; Skiba, Franciszek; Szkoda, Mariusz; Karczewski, Jakub; Burczyk, Łukasz; Śliwiński, Gerard

    2017-10-01

    In this work the results on thermal nanostructuring of the Au films on Ti templates as well as morphology and optical properties of the obtained structures are reported. The bimetal nanostructures are fabricated in a multi-step process. First, the titania nanotubes are produced on the surface of Ti foil by anodization in an ethylene glycol-water solution containing fluoride ions. This is followed by chemical etching in oxalic acid and results in a highly ordered dimpled surface. Subsequently, thin gold films (5-20 nm) are deposited onto prepared Ti substrates by magnetron sputtering. The as-prepared layers are then dewetted by the UV nanosecond laser pulses or alternatively in the furnace (temperature cavity diameter: ∼100 nm) covered with Au nanoparticles (NPs). It is observed that both the laser annealing and continuous thermal treatment in furnace can lead to the creation of NPs inside every Ti dimple and result in uniform coating of the whole area of structured templates. The size and localization of NPs obtained via both dewetting processes as well as their shape can be tuned by the annealing time and the laser processing parameters and also by initial thickness of Au layer and presence of the dimples themselves in the substrate. Results confirm that the prepared material can be used as substrate for SERS (Surface Enhanced Raman Spectroscopy).

  14. Characterization of self-assembled electrodes based on Au-Pt nanoparticles for PEMFC application

    Energy Technology Data Exchange (ETDEWEB)

    Valenzuela, E. [Univ. Politecnica de Chiapas (Mexico). Energia y Sustentabilidad; Sebastian, P.J.; Gamboa, S.A.; Joseph, S. [Univ. Nacional Autonoma de Mexico, Morelos (Mexico). Centrode Investigacion en Energia; Pal, U. [Univ. Autonoma de Puebla, Pue (Mexico). Inst. de Fisica; Gonzalez, I. [Univ. Autonoma Metropolitana, Mexico City (Mexico). Dept. de Quimica

    2010-07-01

    This paper described the synthesis and characterization of gold (Au), platinum (Pt) and Au-Pt nanoparticles impregnated on a Nafion membrane in a proton exchange membrane fuel cell (PEMFC). The aim of the study was to fabricate the membrane electrode assembly (MEA) by depositing the nanoparticles on the membrane using an immersion technique. Scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) were used to study the deposition process. Electrochemical impedance spectroscopy (EIS) was used to study the membrane proton conduction process. An elemental mapping analysis was performed in order to study the location of the Au and Pt in the self-assemblies. Results of the study showed that the particles deposited on the Nafion had good stability and a homogenous distribution along the membrane surface. The particles showed a direct relation in size and location with the hydrophilic and hydrophobic distribution phases of the membrane. The main membrane resistance was located between the membrane and the electrolyte. The self-assembled electrodes demonstrated a good performance at standard conditions. 33 refs., 4 tabs., 11 figs.

  15. Partially and fully de-alloyed glassy ribbons based on Au: Application in methanol electro-oxidation studies

    Energy Technology Data Exchange (ETDEWEB)

    Paschalidou, Eirini Maria, E-mail: epaschal@unito.it [Dipartimento di Chimica e Centro Interdipartimentale NIS (Nanostructured Surfaces and Interfaces), Università di Torino, Via Pietro Giuria 7, 10125, Torino (Italy); Scaglione, Federico [Dipartimento di Chimica e Centro Interdipartimentale NIS (Nanostructured Surfaces and Interfaces), Università di Torino, Via Pietro Giuria 7, 10125, Torino (Italy); Gebert, Annett; Oswald, Steffen [Leibniz Institut für Festkörper- und Werkstoffforschung IFW, Helmholtzstraße 20, 01069, Dresden (Germany); Rizzi, Paola; Battezzati, Livio [Dipartimento di Chimica e Centro Interdipartimentale NIS (Nanostructured Surfaces and Interfaces), Università di Torino, Via Pietro Giuria 7, 10125, Torino (Italy)

    2016-05-15

    In this work, electrochemical de-alloying of an amorphous alloy, Au{sub 40}Cu{sub 28}Ag{sub 7}Pd{sub 5}Si{sub 20}, cast in ribbon form by melt spinning, has been performed, obtaining self standing nanoporous materials suitable for use as electrodes for electrocatalytic applications. The de-alloying encompasses removal of less noble elements and the crystallization of Au, resulting in interconnected ligaments whose size and morphology are described as a function of time. Depending on de-alloying time, the crystals may contain residual amounts of Cu, Ag and Pd, as shown by Auger Electron Spectroscopy (AES), Energy Dispersive Spectroscopy (EDS) and Cyclic Voltammetry (CV) in a basic solution. Current density peaks in the 0.16–0.28 V range (vs Ag/AgCl) indicate that the porous ribbons are active for the electro-oxidation of methanol. The partially de-alloyed samples, which still partially contain the amorphous phase because of the shorter etching times, have finer ligaments and display peaks at lower potential. However, the current density decreases rapidly during repeated potential scans. This is attributed to the obstruction of Au sites, mainly by the Cu oxides formed during the scans. The fully de-alloyed ribbons display current peaks at about 0.20 V and remain active for hundreds of scans at more than 60% of the initial current density. They can be fully re-activated to achieve the same performance levels after a brief immersion in nitric acid. The good activity is due to trapped Ag and Pd atoms in combination with ligament morphology. - Graphical abstract: Fine ligaments and pores made by de-alloying a glassy ribbon of a Au-based alloy, homogeneously produced across the thickness (25 μm) for studying methanol's electro-oxidation behavior. - Highlights: • Size and composition of nanoporous layers tailored in de-alloying Au-based glassy ribbons. • From amorphous precursor fine crystals occur in ligaments with residual Pd and Ag. • Fully de

  16. Transfert : les déterminants de la performance des exploitations agricoles familiales

    OpenAIRE

    Lepage, Fanny; Couderc, Jean Pierre; Perrier, Jean-Philippe; Parent, Diane

    2011-01-01

    Le transfert des exploitations familiales est une étape cruciale du cycle de vie de la majorité des exploitations agricoles québécoises. Avec un taux élevé d’échec important de 40 à 50 % dans les cinq années suivant le transfert d’une PME, il est important de connaître les causes de ces échecs ainsi que les déterminants de la performance des exploitations survivantes après le cap des premières années. Cet article présente les déterminants financiers et technico-économiques de cette performanc...

  17. Dynamics of Green AuNP Formation and Their Application in Core-Shell Nanostructures

    DEFF Research Database (Denmark)

    Engelbrekt, Christian; Zhang, Jingdong; Jensen, Palle Skovhus

    The formation of gold nanoparticles in our optimized synthesis is achieved through reduction of tetrachloroauric acid in 2 - (N - morpholino)ethanesulphonic acid (MES) buffered glucose and stabilization by starch at room temperature. The formation has been followed by measuring the electrochemical...... potential, conductivity, pH, turbidity, UV - Vis extinction , core size and hydrodynamic diameter . The synthesized AuNPs have been employed as core particles in advanced core - shell structures with highly porous platinum nanoparticle coating or copper oxide shells. These hold poten- tials as effective...

  18. Etude des Performances d’une Structure MOS Nanométrique : Application au DGFET

    OpenAIRE

    LARIBI, ASMA

    2010-01-01

    L’évolution des transistors MOSFET qui suit les prédictions de la Loi de Moore depuis plus de 30 ans a permis la réduction des dimensions jusqu’à des dispositifs de longueur de grille de 65 nm. Pour de telles dimensions, les dispositifs conventionnels sur substrat massif souffrent de dégradations notamment en termes de vitesse de commutation des circuits et de consommation en puissance. Jusqu’au noeud 45 nm, l’intégration de transistors sur substrats SOI complètement déplétés permet de réduir...

  19. Synthesis by picosecond laser ablation of ligand-free Ag and Au nanoparticles for SERS applications

    Science.gov (United States)

    Fazio, Enza; Spadaro, Salvatore; Santoro, Marco; Trusso, Sebastiano; Lucotti, Andrea.; Tommasini, Matteo.; Neri, Fortunato; Maria Ossi, Paolo

    2018-01-01

    The morphological and optical properties of noble metal nanoparticles prepared by picosecond laser generated plasmas in water were investigated. First, the ablation efficiency was maximized searching the optimal focusing conditions. The nanoparticle size, measured by Scanning Transmission Electron Microscopy, strongly depends on the laser fluence, keeping fixed the other deposition parameters such as the target to scanner objective distance and laser repetition frequency. STEM images indicate narrow gradients of NP sizes. Hence the optimization of ablation parameters favours a fine tuning of nanoparticles. UV-Visible spectroscopy helped to determine the appropriate laser wavelength to resonantly excite the localized surface plasmon to carry out Surface Enhanced Raman Scattering (SERS) measurements. The SERS activity of Ag and Au substrates, obtained spraying the colloids synthesized in water, was tested using crystal violet as a probe molecule. The good SERS performance, observed at excitation wavelength 785 nm, is attributed to aggregation phenomena of nanoparticles sprayed on the support.

  20. Crystallographic investigation of Au nanoparticles embedded in a SrTiO{sub 3} thin film for plasmonics applications by means of synchrotron radiation

    Energy Technology Data Exchange (ETDEWEB)

    Pincini, Davide, E-mail: davide.pincini@mail.polimi.it [European Synchrotron Radiation Facility, CS 40220, 71, avenue des Martyrs, F-38043 Grenoble Cedex 9 (France); Dipartimento di Fisica, Politecnico di Milano, Piazza Leonardo Da Vinci 32, 20133 Milano (Italy); Mazzoli, Claudio [Dipartimento di Fisica, Politecnico di Milano, Piazza Leonardo Da Vinci 32, 20133 Milano (Italy); Bernhardt, Hendrik; Katzer, Christian; Schmidl, Frank [Institut für Festkörperphysik, Friedrich-Schiller-Universität Jena, Helmholtzweg 5, 07743 Jena (Germany); Uschmann, Ingo [Institut für Optik und Quantenelektronik, Friedrich-Schiller-Universität Jena, Max-Wien-Platz 1, 07743 Jena (Germany); Detlefs, Carsten [European Synchrotron Radiation Facility, CS 40220, 71, avenue des Martyrs, F-38043 Grenoble Cedex 9 (France)

    2015-03-14

    Self-organized monocrystalline Au nanoparticles with potential applications in plasmonics are grown in a SrTiO{sub 3} matrix by a novel two-step deposition process. The crystalline preferred orientation of these Au nanoparticles is investigated by synchrotron hard x-ray diffraction. Nanoparticles preferentially align with the (111) direction along the substrate normal (001), whereas two in-plane orientations are found with [110]{sub SrTiO{sub 3}}∥[110]{sub Au} and [100]{sub SrTiO{sub 3}}∥[110]{sub Au}. Additionally, a smaller diffraction signal from nanoparticles with the (001) direction parallel to the substrate normal (001) is observed; once again, two in-plane orientations are found, with [100]{sub SrTiO{sub 3}}∥[100]{sub Au} and [100]{sub SrTiO{sub 3}}∥[110]{sub Au}. The populations of the two in-plane orientations are found to depend on the thickness of the gold film deposited in the first step of the growth.

  1. Novel electrochemical redox-active species: one-step synthesis of polyaniline derivative-Au/Pd and its application for multiplexed immunoassay

    Science.gov (United States)

    Wang, Liyuan; Feng, Feng; Ma, Zhanfang

    2015-01-01

    Electrochemical redox-active species play crucial role in electrochemically multiplexed immunoassays. A one-pot method for synthesizing four kinds of new electrochemical redox-active species was reported using HAuCl4 and Na2PdCl4 as dual oxidating agents and aniline derivatives as monomers. The synthesized polyaniline derivative-Au/Pd composites, namely poly(N-methyl-o-benzenediamine)-Au/Pd, poly(N-phenyl-o-phenylenediamine)-Au/Pd, poly(N-phenyl-p-phenylenediamine)-Au/Pd and poly(3,3’,5,5’-tetramethylbenzidine)-Au/Pd, exhibited electrochemical redox activity at −0.65 V, −0.3 V, 0.12 V, and 0.5 V, respectively. Meanwhile, these composites showed high H2O2 electrocatalytic activity because of the presence of Au/Pd. The as-prepared composites were used as electrochemical immunoprobes in simultaneous detection of four tumor biomarkers (carcinoembryonic antigen (CEA), carbohydrate antigen 19-9 (CA199), carbohydrate antigen 72-4 (CA724), and alpha fetoprotein (AFP)). This immunoassay shed light on potential applications in simultaneous gastric cancer (related biomarkers: CEA, CA199, CA724) and liver cancer diagnosis (related biomarkers: CEA, CA199, AFP). The present strategy to the synthesize redox species could be easily extended to other polymers such as polypyrrole derivatives and polythiophene derivatives. This would be of great significance in the electrochemical detection of more analytes. PMID:26577799

  2. Le programme Bolsa Família (Bourse familiale : analyse du programme brésilien de transfert conditionnel de revenus

    Directory of Open Access Journals (Sweden)

    Luciana Mourão

    2012-01-01

    Full Text Available Les programmes de transfert de revenus sont courants dans plusieurs pays et jouent un rôle important dans la lutte contre la pauvreté. Cet article présente un examen des résultats du programme Bolsa Família (Bourse familiale entrepris au Brésil par le gouvernement de Lula da Silva en 2004. Au cours des sept dernières années, de nombreuses évaluations du programme ont été réalisées, ce qui permet d'avoir un aperçu de ses résultats et une vue d'ensemble de ses points forts et de ses points faibles. Cinq aspects clés de ce programme sont abordés dans cet article : (1 l'accès au programme, (2 les résultats en matière de lutte contre la faim, (3 les répercussions financières du programme, (4 les facteurs conditionnels de l'éducation et de la santé, (5 les programmes complémentaires et la mobilité sociale. Des résultats issus de la recherche scientifique ont été présentés pour chacun de ces aspects, et tout résultat considéré comme convergent ou divergent a fait l'objet d'une discussion. La conclusion générale est que le programme a généré des résultats significatifs pour le pays, mais qu'il existe encore des problèmes à prendre en considération, notamment les facteurs conditionnels et la gestion intégrée du programme.

  3. Applications de la tranformee en ondelettes au traitement de l'information optique

    Science.gov (United States)

    Deschenes, Sylvain

    La these presente l'apport d'un outil mathematique recemment decouvert, la transformee en ondelettes, au traitement de l'information optique. Les ondelettes continues sont d'abords introduites et leur realisation optique est presentee. Ensuite, une ondelette repondant aux equations de Maxwell est developpee. Cette derniere permet de tisser des liens entre la transformee en ondelettes et le principe de Huygens utilise pour etudier la diffraction scalaire. La possibilite d'utiliser cette ondelette pour generer des faisceaux non diffractants est egalement discutee. Dans un deuxieme temps, les ondelettes discretes sont utilisees dans le but d'extraire des informations pertinentes dans une banque d'images infrarouges. Ces images representent les vues de vehicules prises a tous les cinq degres. La transformee en ondelettes genere une analyse multiresolution permettant d'extraire des contours moins bruites. Cette information est alors traitee par de nouveaux algorithmes de reconnaissance de forme dans un espace qui caracterise de facon invariante les objets 3-D.

  4. Molecular beam epitaxy of GaAs nanowires and their sustainability for optoelectronic applications. Comparing Au- and self-assisted growth methods

    Energy Technology Data Exchange (ETDEWEB)

    Breuer, Steffen

    2011-09-28

    In this work the synthesis of GaAs nanowires by molecular beam epitaxy (MBE) using the vapour-liquid-solid (VLS) mechanism is investigated. A comparison between Au- and self-assisted VLS growth is at the centre of this thesis. While the Au-assisted method is established as a versatile tool for nanowire growth, the recently developed self-assisted variation results from the exchange of Au by Ga droplets and thus eliminates any possibility of Au incorporation. By both methods, we achieve nanowires with epitaxial alignment to the Si(111) substrates. Caused by differences during nanowire nucleation, a parasitic planar layer grows between the nanowires by the Au-assisted method, but can be avoided by the self-assisted method. Au-assisted nanowires grow predominantly in the metastable wurtzite crystal structure, while their self-assisted counterparts have the zincblende structure. All GaAs nanowires are fully relaxed and the strain arising from the lattice mismatch between GaAs and Si of 4.1 % is accommodated by misfit dislocations at the interface. Self-assisted GaAs nanowires are generally found to have vertical and non-polar side facets, while tilted and polar nanofacets were described for Au-assisted GaAs nanowires. We employ VLS nucleation theory to understand the effect of the droplet material on the lateral facets. Optoelectronic applications require long minority carrier lifetimes at room temperature. We fabricate GaAs/(Al,Ga)As core-shell nanowires and analyse them by transient photoluminescence (PL) spectroscopy. The results are 2.5 ns for the self-assisted nanowires as well as 9 ps for the Au-assisted nanowires. By temperature-dependent PL measurements we find a characteristic activation energy of 77 meV that is present only in the Au-assisted nanowires. We conclude that most likely Au is incorporated from the droplets into the GaAs nanowires and acts as a deep, non-radiative recombination centre.

  5. Fabricating a Homogeneously Alloyed AuAg Shell on Au Nanorods to Achieve Strong, Stable, and Tunable Surface Plasmon Resonances

    KAUST Repository

    Huang, Jianfeng

    2015-08-13

    Colloidal metal nanocrystals with strong, stable, and tunable localized surface plasmon resonances (SPRs) can be useful in a corrosive environment for many applications including field-enhanced spectroscopies, plasmon-mediated catalysis, etc. Here, a new synthetic strategy is reported that enables the epitaxial growth of a homogeneously alloyed AuAg shell on Au nanorod seeds, circumventing the phase segregation of Au and Ag encountered in conventional synthesis. The resulting core–shell structured bimetallic nanorods (AuNR@AuAg) have well-mixed Au and Ag atoms in their shell without discernible domains. This degree of mixing allows AuNR@AuAg to combine the high stability of Au with the superior plasmonic activity of Ag, thus outperforming seemingly similar nanostructures with monometallic shells (e.g., Ag-coated Au NRs (AuNR@Ag) and Au-coated Au NRs (AuNR@Au)). AuNR@AuAg is comparable to AuNR@Ag in plasmonic activity, but that it is markedly more stable toward oxidative treatment. Specifically, AuNR@AuAg and AuNR@Ag exhibit similarly strong signals in surface-enhanced Raman spectroscopy that are some 30-fold higher than that of AuNR@Au. When incubated with a H2O2 solution (0.5 m), the plasmonic activity of AuNR@Ag immediately and severely decayed, whereas AuNR@AuAg retained its activity intact. Moreover, the longitudinal SPR frequency of AuNR@AuAg can be tuned throughout the red wavelengths (≈620–690 nm) by controlling the thickness of the AuAg alloy shell. The synthetic strategy is versatile to fabricate AuAg alloyed shells on different shaped Au, with prospects for new possibilities in the synthesis and application of plasmonic nanocrystals.

  6. Poly(BCB)/Au-nanoparticles hybrid film modified electrode: Preparation, characterization and its application as a non-enzymatic sensor

    International Nuclear Information System (INIS)

    Kumar, S. Ashok; Wang, Sea-Fue; Chang, Yu-Tsern

    2010-01-01

    We report electrochemical preparation and characterization of poly-brilliant cresyl blue (Poly(BCB))/gold nanoparticles (Au-NPs) modified electrode. The Poly(BCB)/Au-NPs modified electrode has been used as an electrochemical sensor for the detection of hydrogen peroxide (H 2 O 2 ) at lower potential (- 0.2 V). The Poly(BCB)/Au-NPs film was characterized by scanning electron microscopy, Uv-visible spectroscopy (Uv-vis) and cyclic voltammetry. We have observed that, Au-NPs attached glassy carbon electrode (Au-NPs/GCE) significantly enhanced the polymerization of BCB compared to bare GCE. The Poly(BCB) film was irreversibly attached onto the Au-NPs modified electrode, the resulting hybrid film modified electrode was electrochemically active in the pH range from 2 to 11. Attachment of Poly(BCB)/Au-NPs hybrid film on the electrode surface was confirmed by Uv-vis spectra. In addition, electrocatalytic properties of the Poly(BCB)/Au-NPs/GCE towards reduction of H 2 O 2 have been investigated, and it was found that the sensitivity, reduction potential as well as the corresponding detection limit were improved as compared to the voltammetric response of the Poly(BCB)/GCE and Au-NPs/GCE. Based on this study, a non-enzymatic electrochemical sensor for the determination of H 2 O 2 has been reported. Moreover, analysis of commercial H 2 O 2 samples was performed using the proposed method and satisfactory results were obtained.

  7. Transfert du Tendon du Muscle Jambier Postérieur : à propos de 24 ...

    African Journals Online (AJOL)

    De janvier 1981 à mars 2007, 24 patients souffrants de paralysie irréversible du SPE, ont bénéficié d'une chirurgie de transfert du tendon du muscle jambier postérieur. Les résultats fonctionnels de cette étude rétrospective ont été quantifiiés par la méthode d'évaluation fonctionnelle de STANMORE. Il s'agissait de 14 ...

  8. Green and facile synthesis of an Au nanoparticles@polyoxometalate/ordered mesoporous carbon tri-component nanocomposite and its electrochemical applications.

    Science.gov (United States)

    Zhang, Yufan; Bo, Xiangjie; Nsabimana, Anaclet; Munyentwali, Alexis; Han, Ce; Li, Mian; Guo, Liping

    2015-04-15

    The one-pot synthesis of a well-defined Au nanoparticles@polyoxometalates/ordered mesoporous carbon (Au@POMs/OMC) tri-component nanocomposite is reported, which is facile, green and rapid. The polyoxometalates were used as both reductant and bridging molecules. The formation of these composite materials was verified by a comprehensive characterization using X-ray diffraction, X-ray photoelectron spectroscopy, energy-dispersive X-ray spectra, scanning electron microscopy, and transmission electron microscopy. The novel nanohybrids of Au@POMs/OMC can provide new features of electrocatalytic activities, because of the synergetic effects of Au nanoparticles and OMC materials. Most importantly, the amperometric measurements show that the Au@POMs/OMC nanohybrids have a high catalytic activity with a good sensitivity, long-term stability, wide linear range, low detection limit, and fast response towards acetaminophenol, H2O2, and NADH detection for application as an enzyme-free biosensor. Copyright © 2014 Elsevier B.V. All rights reserved.

  9. Caféiculture : il faut veiller au grain | CRDI - Centre de recherches ...

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

    31 janv. 2011 ... Sur le marché du café en général, c'est le jeu de l'offre et de la demande qui détermine les prix. Après une décennie .... Comme par le passé, la plus grande partie de la valeur ajoutée par suite du transfert des grains du champ au supermarché demeure, aujourd'hui encore, dans les pays développés.

  10. Theoretical and experimental study of heat transfers and pressure drops along surfaces fitted with herring-bone fins: correlation between geometric and aero thermal parameters; Etudes theorique et experimentale du transfert de chaleur et des pertes de charge de surfaces munies d'ailettes disposees en chevron - correlation entre parametres geometriques et aerothermiques

    Energy Technology Data Exchange (ETDEWEB)

    Pelce, J.; Malherbe, J.; Pierre, B. [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1965-07-01

    Principal results are given of experimental research which has been carried out on the flow of a fluid along a surface fitted with herringbone fins. Aero-thermal tests have been effected on a large number of these surfaces whose geometrical parameters have been made to vary systematically. In particular, work on a large scale model has made it possible to analyse the mechanisms of heat transfer and of pressure drops. On this basis a theoretical study has led to the establishment of a correlation between the geometric configuration and the aero-thermal performances of these surfaces. Experimental results are in good agreement with the theoretical relationships. An expression has thus been derived applicable to this type of herring-boned surface in a wide zone. (authors) [French] L'ecoulement d'un fluide au voisinage d'une surface munie d'ailettes disposees en chevron a fait l'objet de recherches experimentales dont on a rappele les principaux resultats. Des essais aerothermiques ont ete effectues sur un grand nombre de ces surfaces dont a fait varier les parametres geometriques de facon systematique. En particulier, des etudes sur une maquette a grande echelle ont permis d'analyser les mecanismes de transfert de chaleur et de perte de charge. Sur ces bases, une etude theorique a conduit a des correlations entre la geometrie et les performances aerothermiques de ces surfaces. Les resultats experimentaux sont en bon accord avec les relations theoriques. On possede ainsi une formulation pour ce type de surface ailettee valable dans un domaine etendu. (auteurs)

  11. Adapter ses méthodes de détermination de prix de transfert pour éroder sa base fiscale : le cas Starbucks

    OpenAIRE

    Quévy, Victor

    2017-01-01

    Ce mémoire s’articule en deux parties. La première, théorique, analysera les prix de transfert via les différents rapports fournis par l’OCDE en se concentrant sur les actions de son plan de lutte contre les pratiques d’érosion fiscales (BEPS) qui concernent les prix de transfert. S’en suivra une analyse des méthodes de valorisation des prix de transfert pour pouvoir les utiliser dans la partie pratique et aussi leurs usages abusifs pour voir dans quelle mesure les multinationales peuvent s’e...

  12. Fe2O3-Au hybrid nanoparticles for sensing applications via sers analysis

    International Nuclear Information System (INIS)

    Murph, Simona Hunyadi; Searles, Emily

    2017-01-01

    Nanoparticles with large amounts of surface area and unique characteristics that are distinct from their bulk material provide an interesting application in the enhancement of inelastic scattering signal. Surface Enhanced Raman Spectroscopy (SERS) strives to increase the Raman scattering effect when chemical species of interest are in the close proximity of metallic nnaostructures. Gold nanoparticles of various shapes have been used for sensing applications via SERS as they demonstrate the greatest effect of plasmonic behavior in the visible-near IR region of the spectrum. When coupled with other nanoparticles, namely iron oxide nanoparticles, hybrid structures with increased functionality were produced. Multifunctional iron oxide-gold hybrid nanostructures have been created via solution chemistries and investigated for analyte detection of a model analyte. By exploiting their magnetic properties, nanogaps or “hot spots” were rationally created and evaluated for SERS enhancement studies.

  13. Synthesis, characterization and in vitro biocompatibility study of Au/TMC/Fe3O4 nanocomposites as a promising, nontoxic system for biomedical applications

    Directory of Open Access Journals (Sweden)

    Hanieh Shirazi

    2015-08-01

    Full Text Available The unique properties and applications of iron oxide and Au nanoparticles have motivated researchers to synthesize and optimize a combined nanocomposite containing both. By using various polymers such as chitosan, some of the problems of classic core–shell structures (such as reduced saturation magnetization and thick coating have been overcome. In the present study, chitosan and one of its well-known derivatives, N-trimethylchitosan (TMC, were applied to construct three-layer nanocomposites in an Au/polymer/Fe3O4 system. It was demonstrated that replacement of chitosan with TMC reasonably improved the properties of the final nanocomposites including their size, magnetic behavior and thermal stability. Moreover, the results of the MTT assay showed no significant cytotoxicity effect when the Au/TMC/Fe3O4 nanocomposites were applied in vitro. These TMC-containing magnetic nanoparticles are well-coated by Au nanoparticles and have good biocompatibility and can thus play the role of a platform or a label in various fields of application, especially the biomedical sciences and biosensors.

  14. Optimization of multilayered Bi-2223/Ag-Au conductors for current lead applications

    International Nuclear Information System (INIS)

    Martini, L.; Barberis, F.; Berti, R.; Bigoni, L.; Curcio, F.; Volpini, G.

    1999-01-01

    Multilayered Bi-2223 composite conductors fabricated by means of the Accordion folding method appear to be suitable for applications as current leads (CL). In this work, the authors report on the results of electrical characterization of silver-gold alloy sheathed Bi-2223 conductors up to 400 mm long, having a DC overall critical current density J ceng exceeding 3000 A/cm 2 at 77 K. The I c evolution from the first to the third thermal treatment as well as the uniformity along the specimen length has been monitored. Lastly, calculations of the magnetic field profile across stacked multilayered Bi-2223 conductors are reported and discussed

  15. Transfers in heterogeneous environments; Transferts en milieux heterogenes

    Energy Technology Data Exchange (ETDEWEB)

    Flesselles, J.M. [Saint-Gobain Recherche, 93 - Aubervilliers (France); Gouesbet, G.; Mees, L.; Roze, C.; Girasole, Th.; Grehan, G. [Laboratoire d' Electromagnetisme et Systemes Particulaires (LESP), UMR CNRS 6614, CORIA. Universite de Rouen et INSA de Rouen, 76 - Saint-Etienne du Rouvray (France); Goyheneche, J.M.; Vignoles, G.; Coindreau, O. [Laboratoire des Composites Thermostructuraux (LCTS), UMR 5801, 33 - Pessac (France); Moyne, Ch. [LEMTA (UMR 7563) CNRS-INPL-UHP, 54 - Vandoeuvre les Nancy (France); Coussy, O. [Institut Navier - ENPC, 77 - Marne-la-Vallee (France); Lassabatere, Th. [Electricite de France Les Renardieres, Dept. Materiaux Mecanique des Composants, 77 - Moret sur Loing (France); Tadrist, L. [IUSTI - UMR 6595, 13 - Marseille (France)

    2004-07-01

    This document gathers the articles and transparencies of the invited talks given at the 2004 French congress of thermal engineering about transfers in heterogeneous environment. Content: transfer phenomena in industrial glass furnaces; simple and multiple scattering diagnosis by femto-second pulsed laser: application to particulate diagnoses; thermal modeling of thermo-structural composites; hybrid mixtures theory, average volumic measurement, periodical or stochastic homogenization: advance in scale change processes; thermo-hydro-chemical-mechanical coupling in porous medium: application to young concrete structures and to clay barriers of disposal facilities; transfers and flows in fluidization: recent advances and future challenges. (J.S.)

  16. Size selectivity of magnetite core- (Ag/Au) shell nanoparticles for multimodal imaging applications

    Science.gov (United States)

    Singh, Pinki; Upadhyay, Chandan

    2017-10-01

    The magnetic and optical properties of nanomaterials play a significant role in the selection of the materials to be used for contrast enhancement in different biological and cell imaging techniques. These nanoparticles can also be used as drug delivery agents. The calculation of absorption efficiency and surface plasmon resonance wavelength has been performed using Mie theory and MATLAB programs. The study of spectrum calculated indicates the dependence of several optical properties such as resonance and absorption efficiency peak on ratio of core radius to the thickness of shell. A systematic study on the effect of nanoparticle dimension has been presented which clearly indicates that the optical properties can be modulated across the visible and near infrared range by changing these parameters. These properties of nanomaterials make them suitable for their application as multimodal imaging agents as they are also magnetically active and biocompatible.

  17. Au-Nano-particle Deposition on alumina surfaces for environmental application-a density functional study

    International Nuclear Information System (INIS)

    Chatterjee, Abhijit

    2009-01-01

    Full text: It has been found that nanometer size gold particles on different oxide supports can act as catalysts, suggestions include quantum size effects, availability of low coordinated sites, and strain or combined effects of the gold particles and the oxide support. From photo dissociation spectroscopy and theory it has been inferred that the 2D / 3D structural transition occurs between five and seven atoms depending on charge state neutrals and singly positively charged ions. Here we will look into the interaction of gold particles over different sites of the aluminum -oxide surface to tune the catalytic activity of the novel material using first principle periodic calculations and compare them with the reactivity index to formulate a priori rule for metal cluster interaction. The catalytic application is aimed to CO adsorption type reactions for a greener environment. (author)

  18. Au102(p-MBA)44 nanocluster, a superatom suitable for bio-applications

    Science.gov (United States)

    Häkkinen, Hannu

    2016-12-01

    Inorganic nanoparticles, including metals, semiconductors and metal oxides, comprise a common set of structures exhibiting an inorganic core `passivated' by an organic shell. Ligated inorganic nanoparticles currently provoke widespread fundamental interest in their structural, optical and magnetic properties, which differ fundamentally from bulk counterparts. These nanomaterials are already finding applications in biology, medicine, solar energy, and display panels. 1-6 Conjugating inorganic nanoparticles with organic (biological) material for applications in nanobiology and nanomedicine creates significant challenges for controlling the effects on the environment, particularly regarding toxicity. Chemical reactions of almost identical substances can lead to drastically different outcomes in a biological environment. As a simplistic example one can consider the case of ethanol vs. methanol. Ethanol (CH3CH2OH) can be consumed by humans while even a small dose of methanol (CH3OH) can be fatal, yet the difference between the molecular formulas of these substances is just the smallest meaningful hydrocarbon unit CH2. This illuminates the fact that minute differences in the size and structure of molecular compounds can have drastically different end effects in a biological environment due to the way the compounds start to react with the environment. In recent years, gold nanoparticles covered by ligands that make them water-soluble have become a popular target for research in nanobiology and nanomedicine. 1,2 In most cases up to now, colloidal nanoparticles (5 nm and larger) have been used for sensing and photothermal applications. However, this class of gold-based nanomaterials still has large uncertainties regarding the atomic composition of the nanoparticle surface and particularly the metal-ligand interface. A simple example illuminates the facts. The density of atoms in the fcc lattice of macrosocopic gold metal is about 59 atoms/nm3. This means that a spherical

  19. Dosimetry and microdosimetry using Let spectrometer based on the track-etch detector: radiotherapy Bremsstrahlung beam, onboard aircraft radiation field; Dosimetrie et micro-dosimetrie au moyen d'un spectrometre a transfert lineique d'energie base sur des detecteurs solides de traces: mesure dans un faisceau de rayonnement X de radiotherapie et du champ de rayonnement a bord d'avion

    Energy Technology Data Exchange (ETDEWEB)

    Jadrneckova, I.; Spurny, F. [Nuclear Physics Institute AS CR, Dept. of Radiation Dosimetry, Prague (Czech Republic); Jadrneckova, I. [Czech Technical Univ., Dept. of Dosimetry and Application of Ionizing Radiation, Prague (Czech Republic)

    2006-10-15

    The spectrometer of linear energy transfer (LET) based on the chemically etched poly-allyl-diglycol-carbonate (PADC) track-etch detector was developed several years ago in our institute. LET spectra are estimated through track parameters determination carried out by an automatic optical image analyzer LUCIA G. This LET spectrometer enables determining LET of particles approximately from 10 to 700 keV/{mu}m. From the LET spectra, dose characteristics can be calculated. This contribution presents the use of this spectrometer in some applications - studies in 18 MV radiotherapy Bremsstrahlung beam and investigation onboard a commercial aircraft during more than 6 months long exposure. The LET spectra obtained in both experiments represent mainly the contribution of secondary or tertiary particles created through the nuclear reactions of photons (Bremsstrahlung beam) or neutrons and neutron-like reacting particles (onboard aircraft) in the detector itself or in the surroundings material. The dose due to the photo-particles represents about 3 x 10{sup -4} of the photon dose; for the dose equivalent this value is about 2 x 10{sup -3} Sv/Gy. Regarding the onboard aircraft exposure, the results obtained using LET spectrometer were compared with those achieved with other methods and a reasonable agreement were stated. (authors)

  20. A rapid green strategy for the synthesis of Au "meatball"-like nanoparticles using green tea for SERS applications

    Science.gov (United States)

    Wu, Shichao; Zhou, Xi; Yang, Xiangrui; Hou, Zhenqing; Shi, Yanfeng; Zhong, Lubin; Jiang, Qian; Zhang, Qiqing

    2014-09-01

    We report a simple and rapid biological approach to synthesize water-soluble and highly roughened "meatball"-like Au nanoparticles using green tea extract under microwave irradiation. The synthesized Au meatball-like nanoparticles possess excellent monodispersity and uniform size (250 nm in diameter). Raman measurements show that these tea-generated meatball-like gold nanostructures with high active surface areas exhibit a high enhancement of surface-enhanced Raman scattering. In addition, the Au meatball-like nanoparticles demonstrate good biocompatibility and remarkable in vitro stability at the biological temperature. Meanwhile, the factors that influence the Au meatball-like nanoparticles morphology are investigated, and the mechanisms behind the nonspherical shape evolution are discussed.

  1. Surface Modification of Carbon Nanotube Networked Films with Au Nanoclusters for Enhanced NO2 Gas Sensing Applications

    Directory of Open Access Journals (Sweden)

    M. Penza

    2008-01-01

    Full Text Available Multiwalled carbon nanotube (MWCNT films have been deposited by using plasma-enhanced chemical vapor deposition (PECVD system onto alumina substrates, provided with 6 nm thick cobalt (Co growth catalyst for remarkably improved NO2 gas sensing, at working temperature in the range of 100–250∘C. Functionalization of the MWCNTs with nanoclusters of gold (Au sputtering has been performed to modify the surface of carbon nanotube networked films for enhanced and specific NO2 gas detection up to sub-ppm level. It is demonstrated that the NO2 gas sensitivity of the MWCNT-based sensors depends on Au-loading used as surface-catalyst. The gas response of MWCNT-based chemiresistor is attributed to p-type conductivity in the Au-modified semiconducting MWCNTs with a very good short-term repeatability and faster recovery. The sensor temperature of maximum NO2 sensitivity of the Au-functionalized MWCNTs is found to decrease with increasing Au-loading on their surface, and continuous gas monitoring at ppb level of NO2 is effectively performed with Au-modified MWCNT chemiresistors.

  2. An enhanced photocatalytic response of nanometric TiO2 wrapping of Au nanoparticles for eco-friendly water applications.

    Science.gov (United States)

    Scuderi, Viviana; Impellizzeri, Giuliana; Romano, Lucia; Scuderi, Mario; Brundo, Maria V; Bergum, Kristin; Zimbone, Massimo; Sanz, Ruy; Buccheri, Maria A; Simone, Francesca; Nicotra, Giuseppe; Svensson, Bengt G; Grimaldi, Maria G; Privitera, Vittorio

    2014-10-07

    We propose a ground-breaking approach by an upside-down vision of the Au/TiO2 nano-system in order to obtain an enhanced photocatalytic response. The system was synthesized by wrapping Au nanoparticles (∼8 nm mean diameter) with a thin layer of TiO2 (∼4 nm thick). The novel idea of embedding Au nanoparticles with titanium dioxide takes advantage of the presence of metal nanoparticles, in terms of electron trapping, without losing any of the TiO2 exposed surface, so as to favor the photocatalytic performance of titanium dioxide. A complete structural characterization was made by scanning electron microscopy, transmission electron microscopy and X-ray diffraction. The remarkable photocatalytic performance together with the stability of the nano-system was demonstrated by degradation of the methylene blue dye in water. The non-toxicity of the nano-system was established by testing the effect of the material on the reproductive cycle of Mytilus galloprovincialis in an aquatic environment. The originally synthesized material was also compared to conventional TiO2 with Au nanoparticles on top. The latter system showed a dispersion of Au nanoparticles in the liquid environment, due to their instability in the aqueous solution that clearly represents an environmental contamination issue. Thus, the results show that nanometric TiO2 wrapping of Au nanoparticles has great potential in eco-friendly water/wastewater purification.

  3. Pulse electrodeposition to prepare core-shell structured AuPt@Pd/C catalyst for formic acid fuel cell application

    Science.gov (United States)

    Lu, Xueyi; Luo, Fan; Song, Huiyu; Liao, Shijun; Li, Hualing

    2014-01-01

    A novel core-shell structured AuPt@Pd/C catalyst for the electrooxidation of formic acid is synthesized by a pulse electrodeposition process, and the AuPt core nanoparticles are obtained by a NaBH4 reduction method. The catalyst is characterized with X-ray powder diffraction and transmission electron microscopy, thermogravimetric analysis, cyclic voltammetry, CO stripping and X-ray photoelectron spectroscopy. The core-shell structure of the catalyst is revealed by the increase in particle size resulting from a Pd layer covering the AuPt core, and by a negative shift in the CO stripping peaks. The addition of a small amount of Pt improves the dispersion of Au and results in smaller core particles. The catalyst's activity is evaluated by cyclic voltammetry in formic acid solution. The catalyst shows excellent activity towards the anodic oxidation of formic acid, the mass activity reaches 4.4 A mg-1Pd and 0.83 A mg-1metal, which are 8.5 and 1.6 times that of commercial Pd/C. This enhanced electrocatalytic activity could be ascribed to the good dispersion of Au core particles resulting from the addition of Pt, as well as to the interaction between the Pd shell layer and the Au and Pt in the core nanoparticles.

  4. Une chaîne de traitement de l'information géographique au service de l'application de la loi Littoral

    Directory of Open Access Journals (Sweden)

    Patrick GUILLOPÉ

    1994-09-01

    Full Text Available L’application de la loi Littoral nécessitait une approche nouvelle de la part de l’État et la mise en œuvre d’outils nouveaux pour une gestion à long terme. L’apport de traitements automatiques de l’information géographique a été ainsi testé au CETE Normandie-Centre sur trois des grands principes posés par cette loi.

  5. Convection mixte lors de l'écoulement d'un fluide de Bingham au sein d'une conduite cylindrique horizontale

    Directory of Open Access Journals (Sweden)

    N. LABSI

    2015-03-01

    Full Text Available La présente étude traite du transfert thermique en mode de convection mixte lors de l'écoulement d'un fluide viscoplastique de Bingham au sein d'une conduite cylindrique horizontale à section droite circulaire, maintenue à température constante et uniforme. Le travail numérique, basé sur la méthode des volumes finis, se focalise sur l'impact de l'intensité des forces de poussée sur le comportement hydrodynamique et thermique de l'écoulement. Les résultats montrent que la structure de l'écoulement se modifie avec l'augmentation du nombre de Grashof. Cette augmentation entraine l'amélioration du transfert thermique et l'augmentation de a perte de charge et ce, dans la zone intermédiaire de la conduite.

  6. Application de la methode des sous-groupes au calcul Monte-Carlo multigroupe

    Science.gov (United States)

    Martin, Nicolas

    This thesis is dedicated to the development of a Monte Carlo neutron transport solver based on the subgroup (or multiband) method. In this formalism, cross sections for resonant isotopes are represented in the form of probability tables on the whole energy spectrum. This study is intended in order to test and validate this approach in lattice physics and criticality-safety applications. The probability table method seems promising since it introduces an alternative computational way between the legacy continuous-energy representation and the multigroup method. In the first case, the amount of data invoked in continuous-energy Monte Carlo calculations can be very important and tend to slow down the overall computational time. In addition, this model preserves the quality of the physical laws present in the ENDF format. Due to its cheap computational cost, the multigroup Monte Carlo way is usually at the basis of production codes in criticality-safety studies. However, the use of a multigroup representation of the cross sections implies a preliminary calculation to take into account self-shielding effects for resonant isotopes. This is generally performed by deterministic lattice codes relying on the collision probability method. Using cross-section probability tables on the whole energy range permits to directly take into account self-shielding effects and can be employed in both lattice physics and criticality-safety calculations. Several aspects have been thoroughly studied: (1) The consistent computation of probability tables with a energy grid comprising only 295 or 361 groups. The CALENDF moment approach conducted to probability tables suitable for a Monte Carlo code. (2) The combination of the probability table sampling for the energy variable with the delta-tracking rejection technique for the space variable, and its impact on the overall efficiency of the proposed Monte Carlo algorithm. (3) The derivation of a model for taking into account anisotropic

  7. Water/rock interactions and mass transport within a thermal gradient Application to the confinement of high level nuclear waste; Interactions solide/solution et transferts de matiere dans un gradient de temperature. Application au confinement des dechets nucleaires de haute-activite

    Energy Technology Data Exchange (ETDEWEB)

    Poinssot, Ch. [CEA Saclay, 91 - Gif-sur-Yvette (France). Dept. d`Entreposage et de Stockage des Dechets]|[Ecole Normale Superieure, 92 - Fontenay-aux-Roses (France). Laboratoire de Geologie

    1998-12-31

    The initial stage of a high level nuclear waste disposal will be characterised by a large heat release within the near-field environment of the canisters. This heat flux caused by radioactive decay will lead to an increase of temperature and a subsequent thermal gradient between the `hot` canisters and the `cold`geological medium. In addition, this thermal gradient will decrease with time due to the heat decay although it could last hundred years. What will be the consequences of such a thermal field varying both on space and time for the alteration of the different constituents of the near field environment. In particular, what could be the effects on the radionuclides migration in the accidental case of an early breach of a canister during the thermal stage? This study brings significant answers to these questions in the light of a performance assessment study. This work is supported by a triple methodological approach involving experimental studies, modelling calculations and a natural analogues study. This complete work demonstrates that a thermal gradient leads to a large re-distribution of elements within the system: some elements are incorporated in the solid phases of the hot end (Si, Zr, Ca) whereas some others are in those of the cold end (Fe, Al, Zn). The confrontation of the results of very simple experiments with the results of a model built on equilibrium thermodynamics allow us to evidence the probable mechanisms causing this mass transport: out-of-equilibrium thermodiffusion processes coupled to irreversible precipitation. Moreover, the effects of the variation of temperatures with time is studied by the way of a natural system which underwent a similar temperature evolution as a disposal and which was initially rich in uranium: the Jurassic Alpine bauxites. In addition, part of the initial bauxite escaped this temperature transformations due to their incorporation in outer thrusting nappes. They are used as a reference. (author)

  8. Induced accumulation of Au, Ag and Cu in Brassica napus grown in a mine tailings with the inoculation of Aspergillus niger and the application of two chemical compounds.

    Science.gov (United States)

    González-Valdez, Eduardo; Alarcón, Alejandro; Ferrera-Cerrato, Ronald; Vega-Carrillo, Héctor René; Maldonado-Vega, María; Salas-Luévano, Miguel Ángel; Argumedo-Delira, Rosalba

    2018-06-15

    This study evaluated the ability of Brassica napus for extracting gold (Au), silver (Ag) and copper (Cu) from a mine tailings, with the inoculation of two Aspergillus niger strains, and the application of ammonium thiocyanate (NH 4 SCN) or ammonium thiosulfate [(NH 4 ) 2 S 2 O 3 ]. After seven weeks of growth inoculated or non-inoculated plants were applied with 1 or 2 g kg -1 of either NH 4 SCN or (NH 4 ) 2 S 2 O 3 , respectively. Eight days after the application of the chemical compounds, plants were harvested for determining the total dry biomass, and the content of Au, Ag, and Cu in plant organs. Application of (NH 4 ) 2 S 2 O 3 or NH 4 SCN resulted in enhanced Au-accumulation in stems (447% and 507%, respectively), while either (NH 4 ) 2 S 2 O 3 +Aspergillus, or NH 4 SCN increased the Au-accumulation in roots (198.5% and 404%, respectively) when compared to the control. Treatments with (NH 4 ) 2 S 2 O 3 or (NH 4 ) 2 S 2 O 3 +Aspergillus significantly increased (P ≤ 0.001) the accumulation of Ag in leaves (677% and 1376%, respectively), while NH 4 SCN + Aspergillus, and (NH 4 ) 2 S 2 O 3 enhanced the accumulation in stems (7153% and 6717.5%). The Ag-accumulation in roots was stimulated by NH 4 SCN+ Aspergillus, and (NH 4 ) 2 S 2 O 3 + Aspergillus (132.5% and 178%, respectively), when compared to the control. The combination of NH 4 SCN+Aspergillus significantly enhanced the Cu-accumulation in leaves (228%); whereas NH 4 SCN+ Aspergillus, or (NH 4 ) 2 S 2 O 3 + Aspergillus resulted in greater accumulation of Cu in stems (1233.5% and 1580%, respectively) than the control. Results suggest that either NH 4 SCN or (NH 4 ) 2 S 2 O 3 (with or without Aspergillus) improved the accumulation of Au and Ag by B. napus. Accumulation of Au and Ag in plant organs overpassed the hyperaccumulation criterion (> 1 mg kg -1 of plant biomass); whereas Cu-accumulation in stems and roots also overpassed such criterion (> 1000 mg kg -1 ) by applying

  9. Preparation of dendritic Ag/Au bimetallic nanostructures and their application in surface-enhanced Raman scattering

    International Nuclear Information System (INIS)

    Yi Zao; Chen Shanjun; Chen Yan; Luo Jiangshan; Wu Weidong; Yi Yougen; Tang Yongjian

    2012-01-01

    Dendritic Ag/Au bimetallic nanostructures have been synthesized via a multi-stage galvanic replacement reaction of Ag dendrites in a chlorauric acid (HAuCl 4 ) solution at room temperature. After five stages of replacement reaction, one obtains structures with protruding nanocubes; these will mature into many porous structures with a few Ag atoms that are left over dendrites. The morphological and compositional changes which evolved with reaction stages were analyzed by using scanning electron microscopy, transmission electron microscopy, UV–visible spectroscopy, selected area electron diffraction and energy-dispersive X-ray spectrometry. The replacement of Ag with Au was confirmed. A formation mechanism involving the original development of Ag dendrites into porous structures with the growth of Au nanocubes on this underlying structure as the number of reaction stages is proposed. This was confirmed by surface-enhanced Raman scattering (SERS). The dendritic Ag/Au bimetallic nanostructures could be used as efficient SERS active substrates. It was found that the SERS enhancement ability was dependent on the stage of galvanic replacement reaction. - Highlights: ► Dendritic Ag/Au bimetallic nanostructures have been synthesized. ► Protruding cubic nanostructures obtained after 5 stages mature into porous structures. ► SERS results allow confirm the proposed formation mechanism. ► The nanostructures could be used as efficient SERS active substrates.

  10. Transfers in multiphase environment; Transferts en milieu multiphasique

    Energy Technology Data Exchange (ETDEWEB)

    Marinhas, S.; Delahaye, A.; Fournaison, L. [Cemagref - GPAN, 92 - Antony (France); Dalmazzone, D.; Furst, W. [Ecole Nationale Superieure de Techniques Avancees (ENSTA), 75 - Paris (France); Petitet, J.P. [Laboratoire d' Ingenierie des Materiaux et des Hautes Pressions (LIMHP), CNRS, 93 - Villetaneuse (France); Trinquet, F.; Royon, L.; Kayossi, H.; Guiffant, G. [Laboratoire Matiere Systeme Complexe, CNRS UMR 7057, 75 - Paris (France); El Omari, L.; Baonga, J.B.; Louahlia-Gualous, H.; Panday, P.K. [Institut FEMTO, Dept. C.R.E.S.T.-UTBM-UFC, UMR CNRS 6174, 90 - Belfort (France); Asbik, M.; Ansari, O. [UFR de Modelisation, Optimisation et Ingenierie des Systemes Energetiques, Faculte des Sciences et Techniques, Errachidia (Morocco); Zeghmati, B. [Perpignan Univ., Laboratoire de Mathematiques et Physique des Systemes, Groupe de Mecanique Energetique (M.E.P.S.-G.M.E.), EA 3086, 66 (France); Jamil, A.; Zeraouli, Y.; Dumas, J.P. [Pau Univ. et des Pays de l' Adour, Lab. de Thermique, Energetique et Procedes (LaTEP), 64 (France); Roux, P.; Fichot, F. [CEA Cadarache, Institut de Radioprotection et de Surete Nucleaire (IRSN), 13 - Saint-Paul-lez-Durance (France); Gobin, D.; Goyeau, B. [Laboratoire FAST, 91 - Orsay (France); Quintard, M. [Institut de Mecanique des Fluides, 31 - Toulouse (France); Barthes, M.; Reynard, Ch.; Santini, R.; Tadrist, L. [Laboratoire IUSTI CNRS UMR 6595, 13 - Marseille (France)

    2005-07-01

    This session about heat and mass transfers in multiphase flows gathers 17 papers dealing with: dynamic study of gas hydrate slurry applied to secondary refrigeration; ice melting inside an agitated reactor: experiment and phenomenological approach; experimental and numerical investigation of the local thickness change of a liquid film dripping around an horizontal tube; evaporation of a liquid film dripping around the external wall of an horizontal tube: laminar-turbulent transition phenomenon; coldness distribution by stabilized ice slurries, study of the behaviour under thermal cycling; study of phases disequilibria of two-phase refrigerating fluids; solidification of binary mixtures, influence of the local chemical non-equilibrium and of the effective transport properties; analysis of heat transfers during the growth of a vapor bubble; forecasting of micro-porosity inside Al-Si alloy smelting parts; estimation of a source term in a 2D transient problem: application to electron beam welding; mesoscopic approach of thermal flows; experimental and numerical study of the impact of a circular jet on a heated disc; inverse conduction method for a jet impacting a rotating cylinder: feasibility study; experimental follow up of a fusion-solidification front with and without transfer promoter; parametric study of a latent heat storage tank during horizontal drainage; stability between two layers of a same supercritical fluid; numerical modeling of the heat transfer inside a stainless steel slab. (J.S.)

  11. Du laboratoire à la mise sur le marché Un Atelier sur les transferts de technologie au CERN

    CERN Multimedia

    CERN Press Office. Geneva

    1997-01-01

    The World-Wide Web, medical imaging, advanced electronic chip design. These are just a few recent results of fundamental research at the World's leading laboratory for particle physics, CERN, in Geneva. Although the Laboratory's mission is pure science, the tools of the trade, particle accelerators and detectors, push the bounds of technology to their limits and beyond.

  12. Controllable growth and transfer of monolayer MoS2 on Au foils and its potential application in hydrogen evolution reaction.

    Science.gov (United States)

    Shi, Jianping; Ma, Donglin; Han, Gao-Feng; Zhang, Yu; Ji, Qingqing; Gao, Teng; Sun, Jingyu; Song, Xiuju; Li, Cong; Zhang, Yanshuo; Lang, Xing-You; Zhang, Yanfeng; Liu, Zhongfan

    2014-10-28

    Controllable synthesis of monolayer MoS2 is essential for fulfilling the application potentials of MoS2 in optoelectronics and valleytronics, etc. Herein, we report the scalable growth of high quality, domain size tunable (edge length from ∼ 200 nm to 50 μm), strictly monolayer MoS2 flakes or even complete films on commercially available Au foils, via low pressure chemical vapor deposition method. The as-grown MoS2 samples can be transferred onto arbitrary substrates like SiO2/Si and quartz with a perfect preservation of the crystal quality, thus probably facilitating its versatile applications. Of particular interest, the nanosized triangular MoS2 flakes on Au foils are proven to be excellent electrocatalysts for hydrogen evolution reaction, featured by a rather low Tafel slope (61 mV/decade) and a relative high exchange current density (38.1 μA/cm(2)). The excellent electron coupling between MoS2 and Au foils is considered to account for the extraordinary hydrogen evolution reaction activity. Our work reports the synthesis of monolayer MoS2 when introducing metal foils as substrates, and presents sound proof that monolayer MoS2 assembled on a well selected electrode can manifest a hydrogen evolution reaction property comparable with that of nanoparticles or few-layer MoS2 electrocatalysts.

  13. Suivi de ligne pour un voilier : application au robot voilier autonome VAIMOS pour l'océanographie

    OpenAIRE

    Le Bars, Fabrice; Jaulin, Luc; Ménage, Olivier

    2013-01-01

    International audience; Bien que les humains utilisent des voiliers depuis des siècles, peu de robots voiliers autonomes existent à ce jour. L'une des principales difficultés pour un robot voilier par rapport à un robot bateau à moteur est de suivre précisément une trajectoire voulue malgré les manoeuvres inhérentes au fonctionnement d'un voilier (lorsque la trajectoire désirée est face au vent par exemple). Dans cet article, nous allons décrire le fonctionnement, le processus de validation e...

  14. Fast and facile preparation of CTAB based gels and their applications in Au and Ag nanoparticles synthesis

    Energy Technology Data Exchange (ETDEWEB)

    Upadhyay, Ravi Kant, E-mail: rkupadhyay85@gmail.com [Department of Chemistry, School of Natural Sciences, Shiv Nadar University, Gautam Budh Nagar, 201314 Uttar Pradesh (India); Soin, Navneet, E-mail: n.soin@bolton.ac.uk [Knowledge Centre for Materials Chemistry (KCMC), Institute for Materials Research and Innovation (IMRI), University of Bolton, Deane Road, Bolton BL3 5AB (United Kingdom); Saha, Susmita, E-mail: ssaha@bose.res.in [Department of Condensed Matter Physics and Material Sciences, S. N. Bose National Centre for Basic Sciences, Block JD, Sector III, Salt Lake, Kolkata 700 098 (India); Barman, Anjan, E-mail: abarman@bose.res.in [Department of Condensed Matter Physics and Material Sciences, S. N. Bose National Centre for Basic Sciences, Block JD, Sector III, Salt Lake, Kolkata 700 098 (India); Sinha Roy, Susanta, E-mail: susanta.roy@snu.edu.in [Department of Physics, School of Natural Sciences, Shiv Nadar University, Gautam Budh Nagar, 201314 Uttar Pradesh (India)

    2015-04-15

    We have demonstrated that the gel-like mesophase of Cetyltrimethylammonium bromide (CTAB) can be synthesized by judicial adjustment of water to surfactant molar ratio (W{sub 0}), without using any additional salts, gelating agents or co-surfactants. Gel formation was found to be highly dependent on the water to surfactant molar ratio (W{sub 0}), with the lowest value of W{sub 0} (41.5) resulting in rapid gel formation. Environmental scanning electron microscope (ESEM) analysis revealed that the gel was comprised of interconnected cylindrical structures. The presence of hydrogen bonding in the gel-like mesophase was confirmed by Fourier Transform Infrared spectroscopy (FTIR) analysis. Rheology measurements revealed that all the gel samples were highly viscoelastic in nature. Furthermore, Au and Ag containing CTAB gels were explored as precursors for the preparation of spherical Gold (Au) and Silver (Ag) nanoparticles using Sodium borohydride (NaBH{sub 4}) as reducing agent. The effects of NaBH{sub 4} concentration on the particle size and morphology of the Au and Ag nanoparticles have also been studied. - Highlights: • A facile synthesis of CTAB based gel-like mesophase is reported. • CTAB gels were obtained by adjusting water to surfactant molar ratio (W{sub 0}). • FTIR analysis revealed that hydrogen bonding plays a key role in gel formation. • Au, Ag nanoparticles were synthesized by using CTAB gel and NaBH{sub 4}.

  15. Magnetic gold nanocatalyst (nanocat-Fe–Au): catalytic applications for the oxidative esterification and hydrogen transfer reactions

    Science.gov (United States)

    An efficient and sustainable protocol is described for the oxidative esterification of aldehydes and the reduction of aromatic nitro compounds that uses magnetically separable and reusable maghemite-supported gold nanocatalyst (nanocat-Fe-Au) under mild conditions. The complex ch...

  16. Rôle des transferts de fonds des migrants dans la promotion du ...

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

    8 déc. 2009 ... Variable. Définition. Source. CPP. Ratio du crédit au secteur privé au PIB. World Bank (2008), World Development. Indicators (2008). DEP. Ratio des dépôts au PIB au PIB. International Monetary Fund (2008),. International Financial Statistics (2008). INF. Taux d'inflation mesuré par la variation de l'indice ...

  17. Mise au point technique de l'élevage de l'Ombrine Sciaenops Ocellata

    OpenAIRE

    Soletchnik, Patrick; Goyard, Emmanuel; Thouard, Emmanuel

    1990-01-01

    Depuis maintenant plus de trois ans, l'équipe IFREMER de Martinique travaille à la mise au point technique de l'élevage de l'ombrine subtropicale (Sciaenops ocellata), dans des conditions intensives. En matière de reproduction, l'équipe IFREMER a engagé dès 1987, une opération de transfert de la technologie Américaine de maturation et ponte grace au contrôle environnemental de la température et de la photopériode. Près de 50 millions d'oeufs ont été produits en 1989, à partir de 5 femelles de...

  18. How Does Amino Acid Ligand Modulate Au Core Structure and Characteristics in Peptide Coated Au Nanocluster?

    Science.gov (United States)

    Li, Nan; Li, Xu; Zhao, Hongkang; Zhao, Lina

    2018-03-01

    The atomic structures and the corresponding physicochemical properties of peptide coated Au nanoclusters determine their distinctive biological targeting applications. To learn the modulation of amino acid ligand on the atomic structure and electronic characteristics of coated Au core is the fundamental knowledge for peptide coated Au nanocluster design and construction. Based on our recent coated Au nanocluster configuration study (Nanoscale, 2016, 8, 11454), we built the typically simplified Au13(Cys-Au-Cys) system to more clearly learn the basic modulation information of amino acid ligand on Au core by the density functional theory (DFT) calculations. There are two isomers as ligand adjacent bonding (Iso1) and diagonal bonding (Iso2) to Au13 cores. The geometry optimizations indicate the adjacent bonding Iso1 is more stable than Iso2. More important, the Au13 core of Iso1 distorts much more significantly than that of Iso2 by Cys-Au-Cys bonding through the root-mean-square deviation (RMSD) analysis, which modulate their electronic characteristics in different ways. In addition, the frontier molecular orbital results of Au13(Cys-Au-Cys) isomers confirm that the Au cores mainly determine the blue shifts of Au13(Cys-Au-Cys) systems versus the original Au13 core in their UV-visible absorption spectrum studies. The configuration of Au13 core performs deformation under Cys-Au-Cys ligand modulation to reach new stability with distinct atomic structure and electronic properties, which could be the theory basis for peptide coated AuNCs design and construction.

  19. Spectral Matrix Filtering Applied to Vsp Processing Application du filtrage matriciel au traitement des profils sismiques verticaux

    Directory of Open Access Journals (Sweden)

    Glangeaud F.

    2006-11-01

    données et de séparer ces signaux. Nous montrons que les signaux peuvent être automatiquement séparés sans connaissance a priori sur leurs vitesses apparentes, en fonction du produit scalaire (calculé dans le domaine fréquentiel et de l'amplitude relative des signaux. Nous montrons des exemples d'application sur des données de sismique de puits. Le filtrage matriciel est effectué dans le domaine fréquentiel en utilisant la matrice spectrale construite à l'aide des intercorrélations des différents enregistrements constituant les données à traiter. Les méthodes d'estimation de la matrice spectrale sont des méthodes de moyenne : moyenne en fréquence (méthode du périodogramme lissé et/ou moyenne en distance (lissage réalisé le long des diagonales de la matrice spectrale. Le lissage en fréquence est obtenu par l'intermédiaire d'une fonction de pondération (par exemple fenêtre de Hanning élevée à une puissance donnée appliquée à chaque corrélation. Les moyennes sont utilisées pour décorréler les signaux et de ce fait favoriser la séparation. Une fois correctement estimée, la matrice spectrale est diagonalisée sur toutes les fréquences du spectre moyenné, et décomposée selon ses vecteurs propres qui sont orthogonaux entre eux et normalisés. Chaque vecteur propre a une valeur propre associée qui représente la répartition d'énergie en fonction de la fréquence du modèle lié au vecteur propre. Le filtrage est réalisé par projection des données sur les différents vecteurs propres issus de la matrice spectrale. Il est à noter cependant que la séparation des différents signaux (projection sur vecteur propre n'est réalisée en terme d'indicatrice sismique que si les événements sismiques sont naturellement orthogonaux et alignés sur les vecteurs propres. Glangeaud et al (1989 ont étudié l'influence des amplitudes relatives et du produit scalaire de deux ondes. Si la vitesse apparente d'une onde est connue, cette derni

  20. Pourquoi croire au modèle du développement territorial au Maghreb ? Une approche critique

    Directory of Open Access Journals (Sweden)

    Kirsten Koop

    2010-09-01

    Full Text Available Depuis la décolonisation, plusieurs modèles de développement ont fait l’objet de transferts de la France vers les pays du Maghreb. La crise du développement industriel a ouvert la voie au développement local à partir des années 1980, et la puissance du mouvement de mondialisation a vu émerger le développement territorial. Depuis le début des années 2000, différents programmes de coopération ont été développés dans le domaine de l’aménagement sur cette thématique entre la France et le Maroc, puis la Tunisie, enfin l’Algérie.Le concept de territoire apparaît central dans les politiques françaises de développement, sa pertinence mérite d'être discutée dans les pays du Maghreb. Il pose en particulier la question de la décentralisation des politiques publiques, et de la capacité des acteurs locaux à participer à la mise en place de systèmes de gouvernance territoriale, deux conditions indispensables à la construction de ressources territoriales spécifiques.Since decolonisation, a succession of development models has been transferred from France towards North African countries. The failure of the industrial development approach on national level opened the way for local development in the late 1980’s, and the power of globalisation dynamics recently gave birth to the “territorial development” model. This new approach towards (economic development and local governance is actually transferred into regional planning practices of Morocco, Tunisia and Algeria on behalf of several French cooperation programs. We here question the relevance of the application of the concept of territory in these North African countries - a concept which turned out to be a central one in French regional planning politics. We particularly analyse the two preconditions for the revealing of specific territorial resources: the decentralisation processes of North African public policies and the capacity of local actors to participate at

  1. EVALUATION DE L’IMPACT ENVIRONNEMENTAL : Evaluation des potentialités de transfert de l’ADN des plantes transgéniques vers les bactéries du sol

    Directory of Open Access Journals (Sweden)

    Simonet Pascal

    2000-07-01

    Full Text Available Les bactéries se caractérisent par leurs stratégies évolutives multiples incluant mutations ponctuelles, remaniements endogènes par déplacements de séquences d’insertion ou de transposons, délétions ou amplifications de larges régions d’ADN et acquisition de nouveaux gènes par transfert horizontal d’informations génétiques. Les récentes et toutes premières analyses conduites sur les données des quelques génomes bactériens totalement séquencés indiquent le rôle tout à fait fondamental qu’ont pu jouer les transferts latéraux de gènes dans l’évolution bactérienne [1-3]. Nombre de travaux sont aujourd’hui conduits afin d’élucider le rôle des trois mécanismes de transfert (conjugaison, transformation et transduction dans l’évolution et l’adaptation des bactéries aux conditions changeantes de leur environnement. En particulier, l’accroissement inquiétant de la proportion de germes résistants aux antibiotiques serait le fait de la dispersion de plasmides porteurs des gènes de résistance parmi la microflore pathogène ? Dans ces cisconstances, la question de savoir si les plantes transgéniques, très souvent pourvues de tels gènes, pourraient constituer un facteur aggravant la dissémination d’éléments menaçant potentiellement la santé humaine est donc totalement justifiée. Tout au long de l’évolution, la nature a cependant établi un certain nombre de filtres moléculaires afin de limiter les flux de gènes, notamment entre organismes phylétiquement très éloignés. La caractéristique des plantes transgéniques tient à ce que certains des gènes des transgènes, et en particulier ceux conférant la résistance aux antibiotiques, ont une origine procaryotique susceptible de leur permettre de contourner les barrières moléculaires. Cependant, d’autres facteurs environnementaux, biotiques et abiotiques vont intervenir pour favoriser ou au contraire limiter les échanges de g

  2. Application de la pensée systémique au renforcement de l'équité ...

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

    Advancing the application of systems thinking in health : realist evaluation of the Leadership Development Programme for district manager decision-making in Ghana. Téléchargez le PDF. Articles de revue. Advancing the application of systems thinking in health: exploring dual practice and its management in Kampala, ...

  3. Development of Ag-Pd-Au-Cu alloys for multiple dental applications. Part 2. Mechanical properties of experimental Ag-Pd-Au-Cu alloys containing Sn or Ga for ceramic-metal restorations.

    Science.gov (United States)

    Goto, S; Nakai, A; Miyagawa, Y; Ogura, H

    2001-06-01

    Eighteen Ag-Pd-Au-Cu alloys, consisting of nine Ag-Pd-Au-Cu mother compositions (Pd: 20, 30 or 40%, Au: 20%, Cu: 10, 15 or 20%, Ag: balance) containing either 5% Sn or 5% Ga as an additive metal, were experimentally prepared. Tensile strength, proof stress, elongation, elastic modulus, and Vickers hardness of these alloys were evaluated to clarify the potential of these alloys for use as ceramic-metal restorations as well as the effects of the Pd and Cu contents on their mechanical properties. The tensile strength, proof stress, elongation, elastic modulus and Vickers hardness of the 18 experimental alloys were in the range of 410.0-984.0 MPa, 289.7-774.3 MPa, 2.2-23.7%, 81.3-123.0 GPa and 135.7-332.3 HV1, respectively. Ten of the 18 experimental alloys can be used for ultra-low fusing ceramics based on their proof stress, elastic modulus, elongation and hardness. Between the Ga- and Sn-added alloys, differences in tensile strength, proof stress, elongation and hardness were found at several Ag-Pd-Au-Cu compositions.

  4. Etude de la levée de dormance et du débourrement des bourgeons de noyer (Juglans regia L., cv Franquette) soumis à des températures supérieures à 15 °C au cours de leur période de repos apparent

    OpenAIRE

    Mauget, Jean-Claude

    1983-01-01

    Des noyers (Juglans regia L., cv. « Franquette »), soumis à la température toujours supérieure à 15 °C d’une serre climatisée, à partir de septembre, octobre, novembre ou décembre, entrent en végétation plus tardivement que les témoins restés à l’extérieur ; le retard est d’autant plus grand que le transfert dans des conditions supérieures à 15 °C est réalisé plus précocement. Si l’on effectue ce transfert en janvier, on observe au contraire un débourrement beaucoup plus précoce. Ces deu...

  5. Fabrication and spectroscopic studies of folic acid-conjugated Fe3O4@Au core-shell for targeted drug delivery application

    Science.gov (United States)

    Karamipour, Sh.; Sadjadi, M. S.; Farhadyar, N.

    2015-09-01

    Gold coated magnetite core shell is a kind of nanoparticle that include magnetic iron oxide core with a thin layer nanogold. Fe3O4-gold core-shell nanostructure can be used in biomedical applications such as magnetic bioseparation, bioimaging, targeting drug delivery and cancer treatment. In this study, the synthesis and characterization of gold coated magnetite nanoparticles were discussed. Magnetite nanoparticles with an average size of 6 nm in diameter were synthesized by the chemical co-precipitation method and gold-coated Fe3O4 core-shell nanostructures were produced with an average size of 11.5 nm in diameter by reduction of Au3+ with citrate ion in the presence of Fe3O4. Folate-conjugated gold coated magnetite nanoparticles were synthesized to targeting folate receptor that is overexpressed on the surface of cancerous cells. For this purpose, we used L-cysteine, as a bi-functional linker for attachment to gold surface and it was linked to the gold nanoparticles surface through its thiol group. Then, we conjugated amino-terminated nanoparticles to folic acid with an amide-linkage formation. These gold magnetic nanoparticles were characterized by various techniques such as X-ray powder diffraction (XRD) analysis, Fourier transform infrared spectrometer (FT-IR), UV-visible spectroscopy, transmission electron microscopy (TEM), field emission scanning electron microscopy (FESEM), dispersive analysis of X-ray (EDAX) and vibrating sample magnetometer (VSM) analysis. The magnetic and optical properties of Fe3O4 nanostructure were changed by gold coating and attachment of L-cysteine and folic acid to Fe3O4@Au nanoparticles.

  6. Influence du type d’addition minérale sur les propriétés de transfert des Bétons AutoPlaçants Influence of the type of mineral admixtures on the transport properties of self compacting concrete

    Directory of Open Access Journals (Sweden)

    Khelafi H.

    2012-09-01

    Full Text Available La formulation des bétons autoplaçants (BAP présente certaines spécificités dont un volume élevé de pâte et une quantité importante d’ajouts minéraux. Ces deux paramètres influencent sensiblement les propriétés de transfert de ces bétons. Dans ce travail, nous avons étudié l’influence de la nature et du pourcentage de plusieurs additions minérales sur certaines propriétés de transfert (la diffusion des ions chlore et la perméabilité au gaz des BAP. Trois différentes additions minérales ont été testées : des fillers calcaires, de la pouzzolane naturelle et des cendres volantes. Ensuite, nous avons cherché une probable relation analytique entre ces propriétés et la résistance à la compression de ces bétons. Au total, douze formulations ont été étudiées, elles couvrent trois différentes classes de résistances (30 MPa, 50 MPa et 70 MPa et quatre types de bétons: un béton ordinaire vibré, un BAP à base de pouzzolanes naturelles, un BAP à base de fillers calcaires et un BAP à base de cendres volantes. Les résultats montrent que la nature de l’addition minérale dans les BAP influe considérablement sur les propriétés de transferts de ces bétons. Après 28, 90 et 360 jours de cure, les BAP contenant de la pouzzolane naturelle représentent des performances très comparables à celles obtenues sur des BAP à base de cendres volantes et bien meilleures que celles obtenues sur des BAP formulés avec du filler calcaire. Indépendamment du type d’addition minérale, les résultats confirment l’existence d’une forte corrélation entre le développement de la résistance à la compression et les propriétés de transferts des BAP. Formulation of self compacting concrete (SCC has some specific characteristics including a high volume of paste and a large amount of mineral admixtures. These two parameters influence significantly the transport properties of SCC. In this work, we studied the influence of

  7. The point-defect of carbon nanotubes anchoring Au nanoparticles

    DEFF Research Database (Denmark)

    Lv, Y. A.; Cui, Y. H.; Li, X. N.

    2010-01-01

    The understanding of the interaction between Au and carbon nanotubes (CNTs) is very important since Au/CNTs composites have wide applications in many fields. In this study, we investigated the dispersion of Au nanoparticles on the CNTs by transmission electron microscopy and the bonding mechanism...

  8. Transport de particules massives dans un fluide turbulent: Application a l'erosion due au sable sur les parois d'une turbine hydraulique

    Science.gov (United States)

    Bergeron, Stephen

    Le transport de particules massives par un champ turbulent est un vaste domaine de la mécanique des fluides. Il possède de nombreuses applications comme par exemple le transport de sable dans une turbine hydraulique. En raison de la dureté des grains de quartz et des grandes vitesses de collision avec les parois métalliques, un phénomène d'érosion intensif se produit. Les dommages résultants peuvent diminuer le rendement de la turbine au cours des quelques mois suivant la mise en opération. L'objectif de cette thèse est de mettre au point un outil permettant de prédire ces zones d'érosion. Ce projet de recherche en contexte industriel a été réalisé en collaboration avec la compagnie General Electric Hydro du Canada. Dans un régime hautement turbulent, il est possible d'obtenir une expression suffisamment générale en utilisant une formulation partiellement empirique: l'équation de Basset- Boussinesq-Oseen modifiée. Ce choix de modèle tient compte du niveau de précision recherché et de la méthode numérique employée afin de résoudre la phase fluide. Il permet aussi d'éliminer plusieurs ambiguïtés fréquemment rencontrées dans la littérature et implementées dans certains codes commerciaux courants. La formulation mathématique du problème est effectuée dans un espace mixte Euler-Lagrange. Les paramètres dynamiques sont relies au type de particules et à l'intensité de la turbulence. Le code numérique résultant est le plus performant développé à ce jour (août 1998). Les trajectoires de plusieurs centaines de milliers de particules peuvent être simulées et visualisées de manière interactive sur une station de travail (SGI R4K, R8K et R10K). L'utilisateur du logiciel est libre de se déplacer dans l'espace à l'aide d'un environnement similaire a un ``simulateur de vol''. Il peut ainsi analyser les détails du processus d'érosion de même que l'écoulement du fluide dans la turbine. Les zones d'érosion obtenues à l

  9. Contribution to the improvement of VRLA batteries for cycling applications; Contribution a l'amelioration des batteries au plomb fermees pour l'application au vehicule electrique

    Energy Technology Data Exchange (ETDEWEB)

    Perrin, M.

    2001-07-01

    Life time and performance of lead batteries for electric-powered vehicles have been optimized by the application of a mechanical pressure on electrodes blocks with a new separator AJS. On the positive grid, the corrosion decreases as the associated effects because AJS stabilizes mechanically the block. The use of phosphoric acid increases the high discharge currant cells performance if they are loaded by an adequate regime. This effect disappears during the cycle. (A.L.B.)

  10. Fe2O3-Au hybrid nanoparticles for sensing applications via sers analysis

    Energy Technology Data Exchange (ETDEWEB)

    Murph, Simona Hunyadi [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL); Searles, Emily [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

    2017-06-25

    Nanoparticles with large amounts of surface area and unique characteristics that are distinct from their bulk material provide an interesting application in the enhancement of inelastic scattering signal. Surface Enhanced Raman Spectroscopy (SERS) strives to increase the Raman scattering effect when chemical species of interest are in the close proximity of metallic nnaostructures. Gold nanoparticles of various shapes have been used for sensing applications via SERS as they demonstrate the greatest effect of plasmonic behavior in the visible-near IR region of the spectrum. When coupled with other nanoparticles, namely iron oxide nanoparticles, hybrid structures with increased functionality were produced. Multifunctional iron oxide-gold hybrid nanostructures have been created via solution chemistries and investigated for analyte detection of a model analyte. By exploiting their magnetic properties, nanogaps or “hot spots” were rationally created and evaluated for SERS enhancement studies.

  11. ÉTUDE DU TRAITEMENT DES SILOXANES PAR ADSORPTION SUR MATÉRIAUX POREUX : APPLICATION AU TRAITEMENT DES BIOGAZ

    OpenAIRE

    Ricaurte Ortega, Deyanira

    2009-01-01

    Study of a treatment of siloxane by adsorption process into porous materials: treatment application to biogas Biogases have strong content of methane used in the production of heat or electricity. They contain more or less important quantities of siloxanes, which are forbidden for numerous uses of biogases. The possibility of siloxanes elimination by adsorption process is studied. The study in batch reactors allows us to evaluate the adsorption capacities of different materials as activated c...

  12. Synthesis and application of strawberry-like Fe3O4-Au nanoparticles as CT-MR dual-modality contrast agents in accurate detection of the progressive liver disease.

    Science.gov (United States)

    Zhao, Hui Y; Liu, Sen; He, Jian; Pan, Chao C; Li, Hui; Zhou, Zheng Y; Ding, Yin; Huo, Da; Hu, Yong

    2015-05-01

    Development of non-invasive assay for the accurate diagnosis of progressive liver diseases (e.g., fatty liver and hepatocellular carcinoma (HCC)) is of great clinical significance and remains to be a big challenge. Herein, we reported the synthesis of strawberry-like Fe3O4-Au hybrid nanoparticles at room temperature that simultaneously exhibited fluorescence, enhanced X-ray attenuation, and magnetic properties. The results of in vitro fluorescence assay showed that the nanoparticles had significant photo-stability and could avoid the endosome degradation in cells. The in vivo imaging of normal mice demonstrated that the Fe3O4-Au nanoparticles provided 34.61-fold contrast enhancement under magnetic resonance (MR) guidance 15 min post the administration. Computed tomography (CT) measurements showed that the highest Hounsfield Unit (HU) was 174 at 30 min post the injection of Fe3O4-Au nanoparticles. In vivo performance of the Fe3O4-Au nanoparticles was further evaluated in rat models bearing three different liver diseases. For the fatty liver model, nearly homogeneous contrast enhancement was observed under both MR (highest contrast ratio 47.33) and CT (from 19 HU to 72 HU) guidances without the occurrences of focal nodules or dysfunction. For the cirrhotic liver and HCC, pronounced enhancement under MR and CT guidance could be seen in liver parenchyma with highlighted lesions after Fe3O4-Au injection. Furthermore, pathological, hematological and biochemical analysis revealed the absence of acute and chronic toxicity, confirming the biocompatibility of our platform for in vivo applications. Collectively, These Fe3O4-Au nanoparticles showed great promise as a candidate for multi-modality bio-imaging. Copyright © 2015 Elsevier Ltd. All rights reserved.

  13. Silica diatom shells tailored with Au nanoparticles enable sensitive analysis of molecules for biological, safety and environment applications

    KAUST Repository

    Onesto, V.

    2018-04-19

    Diatom shells are a natural, theoretically unlimited material composed of silicon dioxide, with regular patterns of pores penetrating through their surface. For their characteristics, diatom shells show promise to be used as low cost, highly efficient drug carriers, sensor devices or other micro-devices. Here, we demonstrate diatom shells functionalized with gold nanoparticles for the harvesting and detection of biological analytes (bovine serum albumin—BSA) and chemical pollutants (mineral oil) in low abundance ranges, for applications in bioengineering, medicine, safety, and pollution monitoring.

  14. Accumulation and interparticle connections of triangular Ag-coated Au nanoprisms by oil-coating method for surface-enhanced Raman scattering applications

    Science.gov (United States)

    Noda, Yuta; Asaka, Toru; Fudouzi, Hiroshi; Hayakawa, Tomokatsu

    2018-03-01

    To examine the optical responses of surface-enhanced Raman scattering (SERS) for tuned plasmonic nanoparticles, triangular Ag-coated Au (Au@Ag) nanoprisms with different sizes were separately synthesized, which were well controlled in their size (edge-length) and localized surface plasmon resonance (LSPR) wavelength (69.0 ± 8.4 to 173.8 ± 25.6 nm in size and 662-943 nm in LSPR wavelength). The mechanism of Ag shell formation on the Au nanoprisms was also studied with scanning transmission electron microscopy-energy dispersive X-ray spectroscopy (STEM-EDS). The Au@Ag nanoprisms were immobilized by covering a colloidal solution containing the nanoprisms with silicone oil and evaporating the solvent in the oil (oil-coating method) so as to form a layer of accumulated plasmonic Au@Ag nanoprisms that had LSPR peak wavelengths tuned from 839 to 1182 nm. The accumulation conditions were analyzed by field-emission scanning electron microscopy (FE-SEM) and a Raman mapping technique. The Au@Ag nanoprisms under excitation at 632.8 nm exhibited higher SERS signals of rhodamine 6G, and SERS-mapped images of the novel immobilized films were obtained at different magnifications. It was concluded that accumulated Au@Ag nanoprisms undergoing tip-planar interconnections could produce enhanced local fields, resulting in higher SERS signals.

  15. Tantalum electrodes modified with well-aligned carbon nanotube-Au nanoparticles: application to the highly sensitive electrochemical determination of cefazolin.

    Science.gov (United States)

    Fayazfar, Haniyeh; Afshar, Abdollah; Dolati, Abolghasem

    2014-07-01

    Carbon nanotube/nanoparticle hybrid materials have been proven to exhibit high electrocatalytic activity suggesting broad potential applications in the field of electroanalysis. For the first time, modification of Ta electrode with aligned multi-walled carbon nanotubes/Au nanoparticles introduced for the sensitive determination of the antibiotic drug, cefazolin (CFZ). The electrochemical response characteristics of the modified electrode toward CFZ were investigated by means of cyclic and linear sweep voltammetry. The modified electrode showed an efficient catalytic activity for the reduction of CFZ, leading to a remarkable decrease in reduction overpotential and a significant increase of peak current. Under optimum conditions, the highly sensitive modified electrode showed a wide linear range from 50 pM to 50 μM with a sufficiently low detection limit of 1 ± 0.01 pM (S/N = 3). The results indicated that the prepared electrode presents suitable characteristics in terms of sensitivity (458.2 ± 2.6 μAcm(-2)/μM), accuracy, repeatability (RSD of 1.8 %), reproducibility (RSD of 2.9 %), stability (14 days), and good catalytic activity in physiological conditions. The method was successfully applied for accurate determination of trace amounts of CFZ in pharmaceutical and clinical preparations without the necessity for samples pretreatment or any time-consuming extraction or evaporation steps prior to the analysis.

  16. Modelisation et commande des redresseurs triphases fonctionnant a haut rendement et a faible taux de distorsion harmonique: Application au redresseur triphase de vienne

    Science.gov (United States)

    Belhadj Youssef, Nesrine

    Les problemes de la qualite de l'onde electrique constituent l'une des preoccupations majeures des fournisseurs de l'energie et des organismes specialises en qualite d'energie. Ce sujet a gagne davantage d'ampleur avec l'utilisation ascendante des convertisseurs de l'energie electrique dans la majorite des applications industrielles et domestiques. Dans le cadre de cette these, on s'interesse plus particulierement au type des convertisseurs alternatif/continu, dont le fonctionnement adequat implique la parfaite regulation du bus DC de tension, l'attenuation des harmoniques de courants, la compensation de l'energie reactive et la maximisation du rendement energetique. Ces differents criteres doivent etre maintenus pour diverses conditions de fonctionnement, c'est-a-dire independamment des variations parametriques auxquelles le systeme peut etre sujet. Il s'avere donc indispensable d'adopter des techniques de commande efficaces, ce qui passe par une modelisation correcte du convertisseur. L'optimisation du nombre de capteurs dans le circuit est egalement un facteur cle a prendre en consideration.

  17. Advanced Characterization Techniques for Nanoparticles for Cancer Research: Applications of SEM and NanoSIMS for Locating Au Nanoparticles in Cells

    OpenAIRE

    Kempen, Paul J; Hitzman, Chuck; Sasportas, Laura S; Gambhir, Sanjiv S; Sinclair, Robert

    2013-01-01

    The ability of nano secondary ion mass spectrometry (NanoSIMS) to locate and analyze Raman active gold core nanoparticles (R-AuNPs) in a biological system is compared with the standard analysis using the scanning electron microscope (SEM). The same cell with R-AuNPs on and inside the macrophage was analyzed with both techniques to directly compare them. SEM analysis showed a large number of nanoparticles within the cell. Subsequent NanoSIMS analysis showed fewer R-AuNPs with lower spatial res...

  18. Ionic liquid assisted synthesis of nano Pd-Au particles and application for the detection of epinephrine, dopamine and uric acid

    Energy Technology Data Exchange (ETDEWEB)

    Tsai, Tsung-Hsuan; Thiagarajan, Soundappan; Chen Shenming, E-mail: smchen78@ms15.hinet.net; Cheng Chingyi

    2012-01-31

    Nano Pd-Au particles have been electrochemically fabricated utilizing ionic liquid as green electrolyte (1-Butyl-3-methylimidazolium tetrafluoroborate). Nano Pd-Au particles modified glassy carbon electrode (GCE) and indium tin oxide coated glass electrodes were examined using atomic force microscopy, field emission scanning electron microscope and X-ray diffraction studies. Electrodeposited nano Pd-Au particles' average diameter was found as 33 nm. Nano Pd-Au particle modified GCE was electrochemically active and stable in various pH solutions. The proposed nano particle modified GCE reduces the over potential and shows the well defined oxidation peaks for the detection of epinephrine and simultaneous determination of dopamine and uric acid (in pH 7.0 phosphate buffer solution) using cyclic voltammetry and differential pulse voltammetry.

  19. Synthesis of double-shelled sea urchin-like yolk-shell Fe3O4/TiO2/Au microspheres and their catalytic applications

    International Nuclear Information System (INIS)

    Li, Jie; Tan, Li; Wang, Ge; Yang, Mu

    2015-01-01

    Double-shelled sea urchin-like yolk-shell Fe 3 O 4 /TiO 2 /Au microspheres were successfully synthesized through loading Au nanoparticles on the Fe 3 O 4 /TiO 2 support by a in situ reduction of HAuCl 4 with NaBH 4 aqueous solution. These microspheres possess tunable cavity size, adjustable shell layers, high structural stability and large specific surface area. The Au nanoparticles of approximately 5 nm in diameter were loaded both on the TiO 2 nanofibers and inside the cavities of sea urchin-like yolk-shell Fe 3 O 4 /TiO 2 microspheres. The sea urchin-like structure composed of TiO 2 nanofibers ensure the good distribution of the Au nanoparticles, while the novel double-shelled yolk-shell structure guarantees the high stability of the Au nanoparticles. Furthermore, the Fe 3 O 4 magnetic core facilitates the convenient recovery of the catalyst by applying an external magnetic field. The Fe 3 O 4 /TiO 2 /Au microspheres display excellent activities and recycling properties in the catalytic reduction of 4-nitrophenol (4-NP): the rate constant is 1.84 min −1 and turnover frequency is 5457 h −1 . (paper)

  20. Synthesis of double-shelled sea urchin-like yolk-shell Fe3O4/TiO2/Au microspheres and their catalytic applications

    Science.gov (United States)

    Li, Jie; Tan, Li; Wang, Ge; Yang, Mu

    2015-03-01

    Double-shelled sea urchin-like yolk-shell Fe3O4/TiO2/Au microspheres were successfully synthesized through loading Au nanoparticles on the Fe3O4/TiO2 support by a in situ reduction of HAuCl4 with NaBH4 aqueous solution. These microspheres possess tunable cavity size, adjustable shell layers, high structural stability and large specific surface area. The Au nanoparticles of approximately 5 nm in diameter were loaded both on the TiO2 nanofibers and inside the cavities of sea urchin-like yolk-shell Fe3O4/TiO2 microspheres. The sea urchin-like structure composed of TiO2 nanofibers ensure the good distribution of the Au nanoparticles, while the novel double-shelled yolk-shell structure guarantees the high stability of the Au nanoparticles. Furthermore, the Fe3O4 magnetic core facilitates the convenient recovery of the catalyst by applying an external magnetic field. The Fe3O4/TiO2/Au microspheres display excellent activities and recycling properties in the catalytic reduction of 4-nitrophenol (4-NP): the rate constant is 1.84 min-1 and turnover frequency is 5457 h-1.

  1. L'algerie, du transfert de technologie a l'economie du savoir et de l ...

    African Journals Online (AJOL)

    Les nouvelles théories de la croissance endogène consa-crent la recherche et le capital humain comme facteurs centraux de la croissance, Plus tard la vision évolutionniste déclasse le marché comme seul moteur de changement technologique et met l'innovation par le biais de l'approche systémique au coeur du ...

  2. Hydrodynamic behaviour of a stirred vessel mass transfer cell; Aspects hydrodynamiques d'une cellule de transfert de masse a agitation des deux phases

    Energy Technology Data Exchange (ETDEWEB)

    Kikindai, T. [Saint Gobain Conceptions Verrieres, 93 - Aubervilliers (France); Morel, J. [Commissariat a l' Energie Atomique, Fontenay-aux-Roses (France). Centre d' Etudes Nucleaires

    1969-07-01

    A theoretical study of mass-transfer coefficients has been made by using the OLANDER'S simplified model, but by attempting a more rigorous resolution of the theoretical equations. Analysis of experimental results and comparison with theoretical results, have shown the importance in interfacial mass transfer of turbulence near the stirrers and consequently in experimental correlations between mass transfer coefficients, properties of the phases (molecular diffusion coefficients, viscosities, etc...) and stirrer rates. (author) [French] Une etude theorique des coefficients de transfert de masse a ete effectuee en utilisant le modele simplifie de OLANDER, mais en essayant de resoudre de facon plus rigoureuse les equations theoriques. Une analyse des resultats experimentaux et une comparaison avec les resultats theoriques, ont montre l'importance des phenomenes de turbulence pres des agitateurs, dans le transfert de masse a l'interface, et par consequent dans les correlations experimentales entre les coefficients de transfert de masse, les proprietes des phases (coefficients de diffusion moleculaire, viscosites, etc...) et les vitesses d'agitation. (auteur)

  3. Au/ZnO nanoarchitectures with Au as both supporter and antenna of visible-light

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Tianyu; Chen, Wei; Hua, Yuxiang; Liu, Xiaoheng, E-mail: xhliu@mail.njust.edu.cn

    2017-01-15

    Highlights: • An inversed Au/ZnO nanostructure was fabricated with ZnO loaded onto Au. • The Au/ZnO nanocomposites showed enhanced properties in visible-light photocatalysis. • The SPR effect of Au was considered important for visible-light photocatalysis. - Abstract: In this paper, we fabricate Au/ZnO nanostructure with smaller ZnO nanoparticles loaded onto bigger gold nanoparticles via combining seed-mediated method and sol-gel method. The obtained Au/ZnO nanocomposites exhibit excellent properties in photocatalysis process like methyl orange (MO) degradation and oxidative conversion of methanol into formaldehyde under visible light irradiation. The enhanced properties were ascribed to the surface plasmon resonance (SPR) effect of Au nanoparticles, which could contribute to the separation of photo-excited electrons and holes and facilitate the process of absorbing visible light. This paper contributes to the emergence of multi-functional nanocomposites with possible applications in visible-light driven photocatalysts and makes the Au/ZnO photocatalyst an exceptional choice for practical applications such as environmental purification of organic pollutants in aqueous solution and the synthesis of fine chemicals and intermediates.

  4. Analyser les œuvres d’art au musée : quels moyens langagiers ?

    OpenAIRE

    Ricker, Marie-Émilie

    2013-01-01

    Présentation et discussion d’un module d’analyse d’œuvres d’art réalisé au Musée d’art moderne de Bruxelles. Cette méthode, transposable dans la formation des instituteurs, s’inscrit dans la théorie de l’apprentissage et de l’enseignement contextualisés (AECA) pour favoriser la construction de connaissances et leur transfert (Frenay et Bedard, 2004). La méthode d’analyse favorise l’observation personnelle inductive (de Chamiec et al. 1982 ; Girard, 1995) et minimise les procédés déductifs afi...

  5. Structural, electronic and magnetic properties of Au-based monolayer derivatives in honeycomb structure

    Energy Technology Data Exchange (ETDEWEB)

    Kapoor, Pooja, E-mail: pupooja16@gmail.com; Sharma, Munish; Ahluwalia, P. K. [Physics Department, Himachal Pradesh University, Shimla, Himachal Pradesh, India 171005 (India); Kumar, Ashok [Centre for Physical Sciences, School of Basic and Applied Sciences, Central University of Punjab, Bathinda, India, 151001 (India)

    2016-05-23

    We present electronic properties of atomic layer of Au, Au{sub 2}-N, Au{sub 2}-O and Au{sub 2}-F in graphene-like structure within the framework of density functional theory (DFT). The lattice constant of derived monolayers are found to be higher than the pristine Au monolayer. Au monolayer is metallic in nature with quantum ballistic conductance calculated as 4G{sub 0}. Similarly, Au{sub 2}-N and Au{sub 2}-F monolayers show 4G{sub 0} and 2G{sub 0} quantum conductance respectively while semiconducting nature with calculated band gap of 0.28 eV has been observed for Au{sub 2}-O monolayer. Most interestingly, half metalicity has been predicted for Au{sub 2}-N and Au{sub 2}-F monolayers. Our findings may have importance for the application of these monolayers in nanoelectronic and spintronics.

  6. Application of a parallel genetic algorithm to the global optimization of medium-sized Au-Pd sub-nanometre clusters

    Science.gov (United States)

    Hussein, Heider A.; Demiroglu, Ilker; Johnston, Roy L.

    2018-02-01

    To contribute to the discussion of the high activity and reactivity of Au-Pd system, we have adopted the BPGA-DFT approach to study the structural and energetic properties of medium-sized Au-Pd sub-nanometre clusters with 11-18 atoms. We have examined the structural behaviour and stability as a function of cluster size and composition. The study suggests 2D-3D crossover points for pure Au clusters at 14 and 16 atoms, whereas pure Pd clusters are all found to be 3D. For Au-Pd nanoalloys, the role of cluster size and the influence of doping were found to be extensive and non-monotonic in altering cluster structures. Various stability criteria (e.g. binding energies, second differences in energy, and mixing energies) are used to evaluate the energetics, structures, and tendency of segregation in sub-nanometre Au-Pd clusters. HOMO-LUMO gaps were calculated to give additional information on cluster stability and a systematic homotop search was used to evaluate the energies of the generated global minima of mono-substituted clusters and the preferred doping sites, as well as confirming the validity of the BPGA-DFT approach.

  7. Au pair trajectories

    DEFF Research Database (Denmark)

    Dalgas, Karina Märcher

    2015-01-01

    Since 2000, thousands of young Filipino migrants have come to Denmark as au pairs. Officially, they are there to “broaden their cultural horizons” by living temporarily with a Danish host family, but they also conduct domestic labor in exchange for food and money, which allows them to send...... of their Danish host families. Based on their migratory status as au pairs, these young migrants must therefore negotiate the different moral and contractual rights and obligations that characterize the local and transnational family ties in which they are engaged. This study of Filipina au pair migration through...... pair-sending families in the Philippines, this dissertation examines the long-term trajectories of these young Filipinas. It shows how the au pairs’ local and transnational family relations develop over time and greatly influence their life trajectories. A focal point of the study is how au pairs...

  8. Hydrodynamique, transfert de chaleur et combustion de gaz naturel en lit fluidisé circulant Hydrodynamics, Heat Transfer and Combustion of Natural Gas in a Circulating Fluidized Bed

    Directory of Open Access Journals (Sweden)

    Feugier A.

    2006-11-01

    Full Text Available L'hydrodynamique, les transferts de chaleur et la combustion du gaz naturel ont été étudiés dans un réacteur à lit circulant de 15 cm de diamètre et de 7 m de haut. Ce réacteur peut opérer avec des vitesses de gaz allant jusqu'à 15 m/s, jusqu'à des températures de 880-900°C et avec des débits de solides compris entre 0 et 15t/h. Les charges utilisées sont des sables de granulométrie allant de 95 à 625 microns. Le profil de concentration en solides dans le réacteur est déterminé à partir du profil de pression. Une corrélation reliant la vitesse de glissement des particules aux principaux paramètres opératoires, rend compte de façon très satisfaisante de l'ensemble des résultats expérimentaux. La mise en place d'un échangeur en paroi dans la partie supérieure du réacteur a permis la détermination de coefficients d'échange thermique. Ces derniers sont essentiellement fonction de la, concentration en particules au droit de l'échangeur et de la granulométrie des particules. Des valeurs allant jusqu'à 200 W/m2 K peuvent, être obtenues. Enfin, la combustion du méthane s'avère très sensible à la présence de particules dans le réacteur. Ces particules ont un effet inhibiteur. Hydrodynamics, heat transfer and combustion of natural gas have been investigated in a circulating-bed reactor 15 cm in diameter and 7 m high. This reactor can operate with gas velocities up to 15 m/s, at temperature up to 880-900°C and with solids flow rates of between 0 and 15 t/h. The solids used are sands with a particle size ranging from 95 to 625 microns. The solids concentration profile in the reactor is determined from the pressure profile. A correlation linking the slippage velocity of particles to the principal operating parameters very satisfactorily takes into consideration the overall experimental results. The installation of a wall heat exchanger in the upper part of the reactor enabled the heat exchange coefficients to be

  9. A simple way to prepare Au@polypyrrole/Fe3O4 hollow capsules with high stability and their application in catalytic reduction of methylene blue dye

    Science.gov (United States)

    Yao, Tongjie; Cui, Tieyu; Wang, Hao; Xu, Linxu; Cui, Fang; Wu, Jie

    2014-06-01

    Metal nanoparticles are promising catalysts for dye degradation in treating wastewater despite the challenges of recycling and stability. In this study, we have introduced a simple way to prepare Au@polypyrrole (PPy)/Fe3O4 catalysts with Au nanoparticles embedded in a PPy/Fe3O4 capsule shell. The PPy/Fe3O4 capsule shell used as a support was constructed in one-step, which not only dramatically simplified the preparation process, but also easily controlled the magnetic properties of the catalysts through adjusting the dosage of FeCl2.4H2O. The component Au nanoparticles could catalyze the reduction of methylene blue dye with NaBH4 as a reducing agent and the reaction rate constant was calculated through the pseudo-first-order reaction equation. The Fe3O4 nanoparticles permitted quick recycling of the catalysts with a magnet due to their room-temperature superparamagnetic properties; therefore, the catalysts exhibited good reusability. In addition to catalytic activity and reusability, stability is also an important property for catalysts. Because both Au and Fe3O4 nanoparticles were wrapped in the PPy shell, compared with precursor polystyrene/Au composites and bare Fe3O4 nanoparticles, the stability of Au@PPy/Fe3O4 hollow capsules was greatly enhanced. Since the current method is simple and flexible to create recyclable catalysts with high stability, it would promote the practicability of metal nanoparticle catalysts in industrial polluted water treatment.Metal nanoparticles are promising catalysts for dye degradation in treating wastewater despite the challenges of recycling and stability. In this study, we have introduced a simple way to prepare Au@polypyrrole (PPy)/Fe3O4 catalysts with Au nanoparticles embedded in a PPy/Fe3O4 capsule shell. The PPy/Fe3O4 capsule shell used as a support was constructed in one-step, which not only dramatically simplified the preparation process, but also easily controlled the magnetic properties of the catalysts through adjusting

  10. Near-infrared-responsive, superparamagnetic Au@Co nanochains

    Directory of Open Access Journals (Sweden)

    Varadee Vittur

    2017-08-01

    Full Text Available This manuscript describes a new type of nanomaterial, namely superparamagnetic Au@Co nanochains with optical extinctions in the near infrared (NIR. The Au@Co nanochains were synthesized via a one-pot galvanic replacement route involving a redox-transmetalation process in aqueous medium, where Au salt was reduced to form Au shells on Co seed templates, affording hollow Au@Co nanochains. The Au shells serve not only as a protective coating for the Co nanochain cores, but also to give rise to the optical properties of these unique nanostructures. Importantly, these bifunctional, magneto-optical Au@Co nanochains combine the advantages of nanophotonics (extinction at ca. 900 nm and nanomagnetism (superparamagnetism and provide a potentially useful new nanoarchitecture for biomedical or catalytic applications that can benefit from both activation by light and manipulation using an external magnetic field.

  11. Analyse des transferts de chaleur et de masse transitoires dans un arena a l'aide de la methode zonale

    Science.gov (United States)

    Daoud, Ahmed

    Cette these presente les resultats d'une etude sur le mouvement de l'air et les transferts thermiques et massiques dans les arenas en regime transitoire et en 3D. Pour la partie aeraulique, il a ete question de developper un modele base sur la methode zonale qui permet de calculer les debits de l'air (dus a la ventilation et aux gradients de temperature) et de l'humidite entre les differentes zones du batiment et de determiner l'age de l'air dans chacune des zones. Pour la partie thermique, un modele de calcul du rayonnement entre les surfaces interieures du batiment qui a ete couple a TRNSYS afin de calculer sur une base annuelle les charges de chauffage et de refrigeration; ces dernieres tiennent compte des transferts radiatif et convectif, de la chaleur latente due a la condensation de l'humidite sur la glace et du surfacage. Le document presente est constitue de 7 chapitres qui peuvent etre resumes comme suit: Les chapitres 1, 2 et 3 sont consacres respectivement: a l'introduction generale, a la revue bibliographique et a la description du batiment modelise. Le chapitre 4 decrit l'approche developpee et la contribution importante qui y est apportee. Il presente l'utilisation de la methode zonale comme une alternative pratique aux methodes CFD car elle permet de realiser des simulations dynamiques sur une annee avec des temps de simulation tres courts et une precision acceptable. Il s'agit d'une approche intermediaire entre les modeles CFD et les modeles a un noeud d'air (considerant la temperature homogene dans un local). Le chapitre 5 est consacre a la methode de resolution numerique. L'outil de simulation a ete developpe en utilisant l'interface du logiciel TRNSYS: Le type 56 de ce logiciel a ete adopte comme modele energetique tandis que les autres modeles ont ete developpes et programmes en utilisant le logiciel MATLAB. Le chapitre 6 presente les resultats de simulation pour un arena sans faux plafond et avec un faux plafond et les resultats de mesures

  12. Intense fluorescence of Au 20

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Chongqi; Harbich, Wolfgang; Sementa, Luca; Ghiringhelli, Luca; Apra, Edoardo; Stener, Mauro; Fortunelli, Alessandro; Brune, Harald

    2017-08-21

    Ligand-protected Au clusters are non-bleaching fluorescence markers in bio- and medical applications. We show that their fluorescence is an intrinsic property of the Au cluster itself. We find a very intense and sharp fluorescence peak located at λ =739.2 nm (1.68 eV) for Au20 clusters in a Ne matrix held at 6 K. The fluorescence reflects the HOMO-LUMO diabatic bandgap of the cluster. The cluster shows a very rich absorption fine structure reminiscent of well defined molecule-like quantum levels. These levels are resolved since Au20 has only one stable isomer (tetrahedral), therefore our sample is mono-disperse in cluster size and conformation. Density-functional theory (DFT) and time-dependent DFT calculations clarify the nature of optical absorptionand predict both main absorption peaks and intrinsic fluorescence in good agreement with experiment.

  13. Facile synthesis and electrochemiluminescence application of concave trisoctahedral Pd@Au core-shell nanocrystals bound by {331} high-index facets.

    Science.gov (United States)

    Zhang, Ling; Niu, Wenxin; Li, Zhiyuan; Xu, Guobao

    2011-10-07

    Concave trisoctahedral (TOH) Pd@Au core-shell nanocrystals bound by {331} facets have been synthesized for the first time. Pd nanocubes and cetyltrimethylammonium chloride were used as the structure-directing cores and capping agents, respectively. Their optical and electrocatalytic properties were investigated. This journal is © The Royal Society of Chemistry 2011

  14. Une analyse du transfert intergénérationnel des connaissances dans les PME familiales du secteur textile au Maroc

    OpenAIRE

    Tahirou Younoussi, Adama

    2012-01-01

    International audience; The aim of this paper is to present the results of research conducted on the intergenerational transfer of knowledge in the family SMEs of Moroccan textile industry. If SMEs are an important part of family firms, they are nevertheless the most vulnerable and at risk of bankruptcy for poor organization or even ineffective knowledge transfer process. With an analytical model developed, we study the characteristics of this process in a Moroccan context, taking into accoun...

  15. Le savoir de l’Europe sur la Chine : transferts franco-allemands au miroir des encyclopédies (1750-1850)

    OpenAIRE

    Lehner, Georg

    2011-01-01

    Les dictionnaires encyclopédiques français et surtout la Description... de la Chine de Du Halde ont influencé durablement les informations sur la Chine contenues dans les encyclopédies allemandes. Toutefois, cette reprise et cette diffusion des travaux français ont également eu des effets en retour et ont conduit à de véritables interactions entre les encyclopédies allemandes et françaises. Les encyclopédies françaises portent mention des travaux des savants allemands ainsi que de leur écho e...

  16. Le droit fiscal à l'épreuve de la mondialisation : la règlementation des prix de transfert au Sénégal

    OpenAIRE

    Ba, El Hadji Dialigue

    2011-01-01

    As a symbol of State sovereignty, tax law is strongly afflicted by globalization and transferpricing are an eloquent testimony. The rules for determining transfer pricing do not guarantee anexact result. The arm’s length principle is difficult to apply and the comparables that ensure theproper implementation are not always available. Therefore, the justification for transfer pricing isoften difficult and sometimes impossible. Senegalese law must be updated, particularly in thesense of providi...

  17. @AuAg nanostructures

    Science.gov (United States)

    Singh, Rina; Soni, R. K.

    2014-09-01

    Bimetallic and trimetallic nanoparticles have attracted significant attention in recent times due to their enhanced electrochemical and catalytic properties compared to monometallic nanoparticles. The numerical calculations using Mie theory has been carried out for three-layered metal nanoshell dielectric-metal-metal (DMM) system consisting of a particle with a dielectric core (Al@Al2O3), a middle metal Ag (Au) layer and an outer metal Au (Ag) shell. The results have been interpreted using plasmon hybridization theory. We have also prepared Al@Al2O3@Ag@Au and Al@Al2O3@AgAu triple-layered core-shell or alloy nanostructure by two-step laser ablation method and compared with calculated results. The synthesis involves temporal separations of Al, Ag, and Au deposition for step-by-step formation of triple-layered core-shell structure. To form Al@Ag nanoparticles, we ablated silver for 40 min in aluminium nanoparticle colloidal solution. As aluminium oxidizes easily in water to form alumina, the resulting structure is core-shell Al@Al2O3. The Al@Al2O3 particle acts as a seed for the incoming energetic silver particles for multilayered Al@Al2O3@Ag nanoparticles is formed. The silver target was then replaced by gold target and ablation was carried out for different ablation time using different laser energy for generation of Al@Al2O3@Ag@Au core-shell or Al@Al2O3@AgAu alloy. The formation of core-shell and alloy nanostructure was confirmed by UV-visible spectroscopy. The absorption spectra show shift in plasmon resonance peak of silver to gold in the range 400-520 nm with increasing ablation time suggesting formation of Ag-Au alloy in the presence of alumina particles in the solution.

  18. Facile Synthesis of Au Nanocube-CdS Core-Shell Nanocomposites with Enhanced Photocatalytic Activity

    Science.gov (United States)

    Liu, Xiao-Li; Liang, Shan; Li, Min; Yu, Xue-Feng; Zhou, Li; Wang, Qu-Qua

    2014-06-01

    Au nanocube-CdS core-shell nanocomposites are prepared by using a one-pot method in aqueous phase with cetyltrimethylammonium bromide as the surfactant. The extinction properties and photocatalytic activity of Au-CdS nanocomposites are investigated. Compared with the pure Au nanocubes, the Au-CdS nanocomposites exhibit enhanced extinction intensity. Compared with CdS nanoparticles, the Au-CdS nanocomposites exhibit improved photocatalytic activity. Furthermore, the photocatalytic efficiency is even better with the increase in the core size of the Au-CdS nanocomposites. Typically, the photocatalytic efficiency of the Au-CdS with 62 nm sized Au nanocubes is about two times higher than that of the pure CdS. It is believed that the Au-CdS nanocomposites may find potential applications in environmental fields, and this synthesis method can be extended to prepare a wide variety of functional composites with Au cores.

  19. Fluorine-18-labelled molecules: synthesis and application in medical imaging; Les molecules marquees au fluor-18. Synthese et application en imagerie medicale

    Energy Technology Data Exchange (ETDEWEB)

    Dolle, F. [Service Hospitalier Frederic Joliot, Groupe de Production des Radiopharmaceutiques, 91 - Orsay (France); Perrio, C. [Centre National de la Recherche Scientifique (CNRS), 75 - Paris (France); Barre, L. [Centre Cyceron, UMR CEA 2E, Groupe de Developpement Methodologiques en Tomographie par Emission en Positons, 14 - Caen (France); Lasne, M.C. [Centre National de la Recherche Scientifique (CNRS), Dept. Chimie, 75 - Paris (France); Le Bars, D. [GIE Cermep, UMR CNRS 5181, Imagerie du Vivant, Methodologie de Synthese et Molecules Bioactives, 69 - Lyon (France)

    2006-10-15

    Positron emission tomography (PET) is one of the more powerful available techniques for medical imaging. It relies on the use of molecules labelled with a positron emitter ({beta}{sup +}). Among those emitters, fluorine-18, available from a cyclotron, is a radionuclide of choice because of its relatively long-half-life (109.8 min) and the relatively low energy of the emitted-positron. The electrophilic form of fluorine-18 ([{sup 18}F]F{sub 2} or reagents derived from [{sup 18}F]F{sub 2}) is mainly used for hydrogen or metal substitutions on aromatic or vinylic carbons. The presence of the stable isotope (fluorine-19) in the radiotracers limits their use in medical imaging. The nucleophilic form of fluorine-18 (alkaline mono-fluoride, K[{sup 18}F]F, the most used), obtained from irradiation of enriched water, is widely used in aliphatic and (hetero)aromatic substitutions for the synthesis of radiotracers with high specific radioactivity. Some examples of radio-fluorinated tracers used in PET are presented, as well as some of their in vivo applications in human. (authors)

  20. The synthesis of Au@C@Pt core-double shell nanocomposite and its application in enzyme-free hydrogen peroxide sensing

    Energy Technology Data Exchange (ETDEWEB)

    Zhang, Yayun; Li, Yuhui; Jiang, Yingying [College of Chemistry & Environment, Minnan Normal University, Zhangzhou 363000 (China); Li, Yancai, E-mail: liyancai@mnnu.edu.cn [College of Chemistry & Environment, Minnan Normal University, Zhangzhou 363000 (China); Fujian Province Key Laboratory of Modern Analytical Science and Separation Technology, Minnan Normal University, Zhangzhou 363000 (China); Li, Shunxing [College of Chemistry & Environment, Minnan Normal University, Zhangzhou 363000 (China); Fujian Province Key Laboratory of Modern Analytical Science and Separation Technology, Minnan Normal University, Zhangzhou 363000 (China)

    2016-08-15

    Highlights: • A novel Au@C@Pt core-double shell nanocomposite was synthesized and characterized by SEM(*), TEM and EDS, etc. • The synthesized Au@C@Pt core-double shell nanocomposite showed high sensitivity and selectivity to electrocatalytic reduction of hydrogen peroxide (H{sub 2}O{sub 2}) and can be used to fabricate enzyme-free H{sub 2}O{sub 2} electrochemical sensor. • The H{sub 2}O{sub 2} sensor has two linear range of 9.0 μM–1.86 mM and 1.86 mM–7.11 mM, respectively, with a low limit of detection of 0.13 μM. • The H{sub 2}O{sub 2} sensor also displays high anti-interference ability, good stability and reproducibility. - Abstract: A novel Au@C@Pt core-double shell nanocomposite was synthesized and used to fabricate enzyme-free electrochemical sensor for rapid and sensitive detection of hydrogen peroxide (H{sub 2}O{sub 2}). The well-designed Au@C@Pt core-double shell nanocomposite was characterized by scanning electron microscopy (SEM), transmission electron microscope (TEM) and energy-dispersed spectrum (EDS). The Au@C@Pt core-double shell nanocomposite modified glassy carbon electrode (Au@C@Pt/GCE) exhibits good electrocatalytic activity towards H{sub 2}O{sub 2} reduction at 0.0 V and can be used as H{sub 2}O{sub 2} sensor. The sensor displays two wide linear ranges towards H{sub 2}O{sub 2} detection. The one is 9.0 μM–1.86 mM with high sensitivity of 144.7 μA mM{sup −1} cm{sup −2}, and the other is 1.86 mM–7.11 mM with sensitivity of 80.1 μA mM{sup −1} cm{sup −2}. When signal to noise (S/N) is 3, the calculated detection limit (LOD) is 0.13 μM. Furthermore, the interference from the common interfering species such as glucose, ascorbic acid, dopamine and uric acid can be effectively avoided to H{sub 2}O{sub 2} detection. Additionally, the H{sub 2}O{sub 2} sensor also displays good stability and reproducibility.

  1. A measuring method of photo-electric cross section. Application to high-Z elements between 40 keV and 220 keV. Measurement of K absorption edge energy of Au, Th, U, Pu

    International Nuclear Information System (INIS)

    Chartier, J.-L.

    1977-09-01

    This study first describes a bent crystal monochromator developed for the production of monochromatic beams in a continuous energy range from 30 to 250 keV; it is completed by a metrological application of the device (determination of K absorption edge energy of Au, Th, U, Pu). A method and the associated experimental procedure were developed to measure the photo-electric cross section for high-Z elements; the results are presented with a relative uncertainty ranging between 3 and 6%. Finally, the experimental values are compared with values calculated from theories using self-consistent potential models [fr

  2. AuNP-RF sensor: An innovative application of RF technology for sensing pathogens electrically in liquids (SPEL) within the food supply chain.

    Science.gov (United States)

    Matta, Leann Lerie; Karuppuswami, Saranraj; Chahal, Premjeet; Alocilja, Evangelyn C

    2018-04-11

    Rapid detection techniques of pathogenic bacteria in the liquid food supply chain are of significant research interest due to their pivotal role in preventing foodborne outbreaks, and in maintaining high standards of public health and safety. Milk and dairy products are of particular interest due to their widespread consumption across the globe. In this paper, a biosensor for detecting pathogenic bacteria in milk using dextrin-capped gold nanoparticles (d-AuNP) as labels decoded at microwave frequencies is presented. The SPEL (sensing pathogens electrically in liquids) biosensor consists of a 3D printed vial and uses an RF reader and an RFID (radio-frequency identification) compatible Split Ring Resonator (SRR) based tag. The SPEL biosensor is capable of detecting bacteria at 5 log CFU/mL within 75 min, with the possibility of testing multiple concurrent samples. Detection is based on impedance loading of SRR by d-AuNP bound to pathogenic bacteria. Spectrophotometry, along with carbohydrate-functionalized magnetic nanoparticle (MNP) cell capture, is used to verify the sensitivity of the SPEL biosensor with respect to d-AuNP presence. The proof-of-concept device, along with challenges and opportunities for commercialization, are also outlined. Copyright © 2018. Published by Elsevier B.V.

  3. Green synthesis, characterization of Au-Ag core-shell nanoparticles using gripe water and their applications in nonlinear optics and surface enhanced Raman studies

    Science.gov (United States)

    Kirubha, E.; Palanisamy, P. K.

    2014-12-01

    In recent years there has been excessive progress in the ‘green’ chemistry approach for the synthesis of gold and silver nanoparticles. Bimetallic nanoparticles have gained special significance due to their unique tunable optical properties. Herein we report a facile one-pot, eco-friendly synthesis of Au-Ag bimetallic core-shell nanoparticles using gripe water as reducing as well as stabilizing agent. The as-synthesized Au-Ag nanoparticles are characterized using UV-Vis spectroscopy to determine the surface plasmon resonance, and using transmission electron microscopy to study the morphology and the particle size. The optical nonlinearity of the bimetallic nanoparticles investigated by z-scan technique using femtosecond Ti:sapphire is in the order of 109. The nonlinear optical parameters such as the nonlinear refractive index n2, nonlinear absorption coefficient β and the third order nonlinear susceptibility χ3 are measured for various wavelengths from 700 nm to 950 nm. The Au-Ag nanoparticles are also used in surface enhanced Raman spectroscopic studies to enhance the Raman signals of rhodamine 6G.

  4. Electrochemical behavior of graphene/Nafion/Azure I/Au nanoparticles composites modified glass carbon electrode and its application as nonenzymatic hydrogen peroxide sensor

    International Nuclear Information System (INIS)

    Zhang, Yanli; Liu, Yanpei; He, Jiemei; Pang, Pengfei; Gao, Yuntao; Hu, Qiufen

    2013-01-01

    A novel nonenzymatic hydrogen peroxide sensor was developed using graphene/Nafion/azure I/Au nanoparticles composites modified glass carbon electrode (graphene/Nafion/AzI/AuNPs/GCE). The method of preparation of graphene/Nafion/AzI/AuNPs composite was simple and it was characterized by SEM. Cyclic voltammetry demonstrated that the direct electron transfer of redox molecule, Azure I, was realized, and the sensor had an excellent performance in terms of electrocatalytic reduction toward hydrogen peroxide (H 2 O 2 ). The sensor showed high sensitivity and fast response upon the addition of H 2 O 2 , under the conditions of pH 4.0, potential −0.2 V. The time to reach the stable-state current was less than 3 s, and the linear range to H 2 O 2 was from 30 μM to 5 mM with a detection limit of 10 μM (S/N = 3). Moreover, the sensor exhibited good reproducibility and long-term stability

  5. Application of ZnO quantum dots dotted carbon nanotube for sensitive electrochemiluminescence immunoassay based on simply electrochemical reduced Pt/Au alloy and a disposable device

    Energy Technology Data Exchange (ETDEWEB)

    Liu, Fang; Deng, Wenping; Zhang, Yan [Key Laboratory of Chemical Sensing and Analysis in Universities of Shandong, School of Chemistry and Chemical Engineering, University of Jinan, Jinan, 250022 (China); Ge, Shenguang [Shandong Provincial Key Laboratory of Preparation and Measurement of Building Materials, University of Jinan, Jinan, 250022 (China); Yu, Jinghua, E-mail: ujn.yujh@gmail.com [Key Laboratory of Chemical Sensing and Analysis in Universities of Shandong, School of Chemistry and Chemical Engineering, University of Jinan, Jinan, 250022 (China); Song, Xianrang, E-mail: sxr@vip.163.com [Cancer Research Center, Shandong Tumor Hospital, Jinan, 250012 (China)

    2014-03-01

    Highlights: • A sandwich-type electrochemluminence immunosensor was fabricated. • Simply electrochemical reduced Pt/Au alloy was selected as immunosensing probes. • ZnO@CNT composite was first employed as signal amplification label. Abstract: We report on a disposable microdevice suitable for sandwich-type electrochemiluminescence (ECL) detection of prostate specific antigen (PSA). The method is making use of ZnO quantum dots dotted carbon nanotube (ZnO@CNT) and simply electrochemical reduced Pt/Au alloy. The latter was selected as immunosensing probe to modify screen-printed carbon electrode, due to its excellent electrical property. For further ultrasensitive, low-potential and stable ECL detection, ZnO@CNT composite was first synthesized using a facile solvothermal method, and employed as signal amplification label. In this work, two working electrodes in one device were used for one determination to obtain more exact results based on screen-print technique. Taking advantage of dual-amplification effects of the Pt/Au and ZnO@CNT, this immunosensor could detect the PSA quantitatively, in the range of 0.001–500 ng mL⁻¹, with a low detection limit of 0.61 pg mL⁻¹. The resulting versatile immunosensor possesses high sensitivity, satisfactory reproducibility and regeneration. This simple and specific strategy has vast potential to be used in other biological assays.

  6. Entre le « bien » et les exigences techniques de la loi. Le cas du prix de transfert

    OpenAIRE

    Vidal, Jean-Pierre

    2015-01-01

    Certains contribuables croient que les fiscalistes peuvent se conformer à la loi sans nécessairement se conformer à l’éthique. Cette opinion remet en cause leur confiance dans le système fiscal et ceux qui sont coupables d’évasion fiscale croient qu’ils ne sont pas les seuls et pas les pires. Dans le domaine du prix de transfert, il existe pourtant de bonnes raisons de croire qu’une entreprise multinationale ne peut pas échapper à ses obligations fiscales légitimes en choisissant de suivre...

  7. Contributions a l'analyse de l'ecoulement et du transfert de chaleur dans les echangeurs de chaleur a plaques

    Science.gov (United States)

    Gherasim, Iulian

    Le but de la presente etude est d'elargir la base de connaissances sur l'ecoulement et le transfert de chaleur dans les echangeurs de chaleur a plaques. Pour cela, une etude experimentale et des simulations numeriques ont ete realisees. Le montage experimental a servi a valider le modele numerique et a explorer le regime de convection mixte. Le modele numerique represente fidelement l'ECP utilise dans ce travail, qui contient deux canaux confines par des plaques de type chevron. La validation a ete faite pour le regime laminaire et pour le regime turbulent, dans lequel un modele de turbulence a ete choisi comme le plus adequat, suite a une etude comparative entre plusieurs modeles. Le modele numerique a ete utilise pour completer les donnees experimentales et pour explorer des niveaux intangibles experimentalement. Ainsi, les champs thermique et d'ecoulement dans cet ECP ont ete etudies pour deux combinaisons de fluide : eau - eau et eau - huile de moteur. On a mis en evidence la non-uniformite du champ de temperatures et le fait que pour ce type particulier d'ECP, les fluides suivent preferentiellement deux passages lisses situes le long des bords des canaux. La dependance du nombre de Reynolds de ces phenomenes a ete mise en evidence. Le modele numerique a pu etre modifie pour evaluer l'effet des canaux lisses peripheriques sur le transfert de chaleur et les pertes de pression. Ce modele consiste de la meme geometrie, avec ces canaux peripheriques obtures. Cette comparaison montre que l'absence des passages lisses provoque l'augmentation du transfert thermique et aussi, des pertes de pression. Une autre modification portant sur la comparaison des configurations verticale et en diagonale a ete faite numeriquement. Des differences quantitatives insignifiantes concernant les performances thermiques et hydrauliques ont ete remarquees. Une investigation sur l'influence de la convection naturelle sur le transfert de chaleur et les pertes de pression a ete faite. Dans

  8. De l'apprentissage théorique à l'étude de cas. Un transfert plus contextualisé.

    OpenAIRE

    Arribillaga Iriarte, Ana; Madariaga Orbea, José Maria

    2012-01-01

    Atelier 11 : Approche longitudinale des pratiques pédagogiques; Si le but de l'éducation est le transfert des connaissances, les recherches nous montrent que l'apprentissage théorique n'est pas suffisant pour que cela se produise. Notre approche considère indispensable que le rôle de l'étudiant soit le principe fondamental. C'est l'étudiant qui construit ses propres connaissances quand il s'approche à des nouvelles réalités inconnues, quand il apprend à choisir les éléments les plus important...

  9. Contaminants chimiques organiques des œufs de poule pondeuse : aspects réglementaires, modalités et risques de transfert

    OpenAIRE

    Fournier, Agnès; Travel, A.; Feidt, Cyril; Roudaut, B.

    2010-01-01

    Le présent article fait le point sur les contaminants chimiques organiques potentiellement présents dans les œufs de poules pondeuses. Ils ont pour origine soit des médicaments vétérinaires, des additifs introduits dans les aliments, des pesticides utilisés pour la production des matières premières entrant dans l’alimentation des animaux ou encore des polluants rémanents de l’environnement. Les médicaments vétérinaires et additifs alimentaires font l’objet d’études strictes de transfert avant...

  10. The Use of Video in Knowledge Transfer of Teacher-Led Psychosocial Interventions: Feeling Competent to Adopt a Different Role in the Classroom / L’utilisation de la vidéo dans le transfert de connaissances dans les interventions psychosociales

    Directory of Open Access Journals (Sweden)

    Caroline Beauregard

    2015-03-01

    Full Text Available Because they propose a form of modeling, videos have been recognised to be useful to transfer knowledge about practices requiring teachers to adopt a different role. This paper describes the results of a satisfaction survey with 98 teachers, school administrators and professionals regarding their appreciation of training videos showing teacher-led psychosocial interventions. The association between teachers’ appreciation of the video and their desire to implement the intervention are explored in terms of authenticity, vicarious learning and self-efficacy, in an attempt to further comprehend how the use of video supports different aspects of modeling (skills - know-how, attitudes - know-how to be. The authors suggest that training videos featuring teachers leading psychosocial interventions support knowledge transfer because learners can relate to successful peers and can think of themselves as competent to replicate the intervention and comfortable to adopt a different role in the classroom. Parce qu’elles proposent une forme de modelage, les vidéos ont été reconnues comme utiles pour le transfert de connaissances au sujet des pratiques exigeant que les enseignants jouent un rôle différent. Cet article décrit les résultats d’une enquête sur la satisfaction réalisée auprès de 98 enseignants, administrateurs et professionnels scolaires quant à leur appréciation des vidéos de formation montrant des interventions psychosociales menées par des enseignants. Le lien entre l’appréciation de la vidéo par les enseignants et leur désir de mettre en pratique l’intervention est exploré en matière d’authenticité, d’apprentissage par procuration et d’auto-efficacité, pour tenter de mieux comprendre comment l’usage de la vidéo appuie différents aspects du modelage (aptitudes, savoir-faire, attitudes, savoir-être. Les auteurs suggèrent que les vidéos de formation montrant des enseignants menant des interventions

  11. L'interaction acteur – système d'information au cœur de la dynamique d'un dispositif d'intelligence territoriale

    OpenAIRE

    Knauf, Audrey

    2005-01-01

    URL : http://isdm.univ-tln.fr/PDF/isdm22/isdm22_knauf.pdf; International audience; Dans cette communication, nous nous intéressons à la démarche d'intelligence économique appliquée au territoire, que l'on appelle désormais intelligence territoriale (IT). Yann Bertacchini la définit comme suit : « [...] l'intelligence territoriale peut être assimilée à la territorialité qui résulte du phénomène d'appropriation des ressources d'un territoire puis aux transferts des compétences entre des catégor...

  12. Catalytic activity of Au nanoparticles

    DEFF Research Database (Denmark)

    Larsen, Britt Hvolbæk; Janssens, Ton V.W.; Clausen, Bjerne

    2007-01-01

    Au is usually viewed as an inert metal, but surprisingly it has been found that Au nanoparticles less than 3–5 nm in diameter are catalytically active for several chemical reactions. We discuss the origin of this effect, focusing on the way in which the chemical activity of Au may change with par......Au is usually viewed as an inert metal, but surprisingly it has been found that Au nanoparticles less than 3–5 nm in diameter are catalytically active for several chemical reactions. We discuss the origin of this effect, focusing on the way in which the chemical activity of Au may change...

  13. Tuning the collective switching behavior of azobenzene/Au hybrid materials: flexible versus rigid azobenzene backbones and Au(111) surfaces versus curved Au nanoparticles.

    Science.gov (United States)

    Liu, Chunyan; Zheng, Dong; Hu, Weigang; Zhu, Qiang; Tian, Ziqi; Zhao, Jun; Zhu, Yan; Ma, Jing

    2017-11-09

    The combination of photo-responsive azobenzene (AB) and biocompatible Au nanomaterials possesses potential applications in diverse fields such as biosensing and thermotherapy. To explore the influence of azobenzene moieties and Au substrates on the collective switching behavior, two different azobenzene derivatives (rigid biphenyl-controlled versus flexible alkoxyl chain-linked) and three different Au substrates (a planar Au(111) surface, curved Au 102 (SR) 44 and Au 25 (SR) 18 clusters) were chosen to form six Au@AB combinations. A reactive molecular dynamics (RMD) model considering both the torsion and inversion path was implemented to simulate the collective photo-induced cis-to-trans switching process of AB monolayers on Au substrates. The major driving force for isomerization is demonstrated to be the torsion of the C-N[double bond, length as m-dash]N-C dihedral angle, in addition to the minor contribution from an inversion pathway. The isomerization process can be divided into the preliminary conformation switching stage and the later relaxation stage, in which a gradual self-organization is observed for 40 ps. The Au substrate affects the packing structure of the AB monolayer, while the choice of different kinds of ABs tunes the intermolecular interaction in the monolayer. Flexible alkoxyl-linked F-AB may achieve much faster conversion on Au clusters than on the surface. For rigid biphenyl-based R-AB anchored on Au nanoparticles (AuNPs), a competitive torsion between the biphenyl and C-N[double bond, length as m-dash]N-C dihedral may delay the C-N[double bond, length as m-dash]N-C dihedral torsion and the following isomerization process. After the R-AB molecules were anchored on the Au(111) surface, the strong π-π stacking between biphenyl units accelerates the collective isomerization process. A curvature-dependent effect is observed for R-AB SAMs on different-sized substrates. The cooperation between functional AB monolayers and the Au substrate

  14. Oxidation and reduction kinetics of eutectic SnPb, InSn, and AuSn: a knowledge base for fluxless solder bonding applications

    DEFF Research Database (Denmark)

    Kuhmann, Jochen Friedrich; Preuss, A.; Adolphi, B.

    1998-01-01

    : (1) SnPb; (2) InSn; (3) AuSn. The studies of the oxidation kinetics show that the growth of the native oxide, which covers the solder surfaces from the start of all soldering operations is self-limiting. The rate of oxidation on the molten, metallic solder surfaces is significantly reduced...... and reduction kinetics, are applied to flip-chip (FC) bonding experiments in vacuum with and without the injection of H2. Wetting in vacuum is excellent but the self-alignment during flip-chip soldering is restricted. The desired, perfectly self-aligned FC-bonds have been only achieved, using evaporated...

  15. Direct electron transfer biosensor for hydrogen peroxide carrying nanocomplex composed of horseradish peroxidase and Au-nanoparticle – Characterization and application to bienzyme systems

    Directory of Open Access Journals (Sweden)

    Yusuke Okawa

    2015-09-01

    Full Text Available A reagentless electrochemical biosensor for hydrogen peroxide was fabricated. The sensor carries a monolayer of nanocomplex composed of horseradish peroxidase and Au-nanoparticle, and responds to hydrogen peroxide through the highly efficient direct electron transfer at a mild electrode potential without any soluble mediator. Formation of the nanocomplex was studied with visible spectroscopy and size exclusion chromatography. The sensor performance was analyzed based on a hydrodynamic electrochemical technique and enzyme kinetics. The sensor was applied to fabrication of sensors for glucose and uric acid through further modification of the nanocomplex-carrying electrode with the corresponding hydrogen peroxide-generating oxidases, glucose oxidase and urate oxidase, respectively.

  16. Preparation of 198Au free from 199Au

    International Nuclear Information System (INIS)

    Capgras, A.

    1967-01-01

    The necessity of obtaining 198 Au free from 199 Au has led us to carry out irradiations using cadmium. The spectra obtained using irradiated detectors with or without cadmium have confirmed the validity of the method. Under the same irradiation conditions the ratio 199 Au/ 198 Au in the first case is of the order of 8 per cent; in the second case this ratio is less than 0.1 per cent. (author) [fr

  17. Contribution a l'etude et au developpement de nouvelles poudres de fonte

    Science.gov (United States)

    Boisvert, Mathieu

    L'obtention de graphite libre dans des pieces fabriquees par metallurgie des poudres (M/P) est un defi auquel plusieurs chercheurs se sont attardes. En effet, la presence de graphite apres frittage ameliore l'usinabilite des pieces, permettant donc de reduire les couts de production, et peut aussi engendrer une amelioration des proprietes tribologiques. L'approche utilisee dans cette these pour tenter d'obtenir du graphite libre apres frittage est par l'utilisation de nouvelles poudres de fontes atomisees a l'eau. L'atomisation a l'eau etant un procede de production de poudres relativement peu couteux qui permet de grandes capacites de production, le transfert des decouvertes de ce doctorat vers des applications industrielles sera donc economiquement plus favorable. En plus de l'objectif d'obtenir du graphite libre apres frittage, un autre aspect important des travaux est le controle de la morphologie du graphite libre apres frittage. En effet, il est connu dans la litterature des fontes coulees/moulees que la morphologie du graphite influencera les proprietes des fontes, ce qui est aussi vrai pour les pieces de M/P. Les fontes ductiles, pour lesquelles le graphite est sous forme de nodules spheroidaux isoles les uns des autres, possedent des proprietes mecaniques superieures aux fontes grises pour lesquelles le graphite est sous forme lamellaire et continu dans la matrice. Les resultats presentes dans cette these montrent qu'il est possible, dans des melanges contenant des poudres de fontes, d'avoir un controle sur la morphologie du graphite et donc sur les proprietes des pieces. Le controle de la morphologie du graphite a principalement ete realise par le type de frittage et le phenomene de diffusion " uphill " du carbone cause par des gradients en silicium. En effet, pour les frittages en phase solide, tous les nodules de graphite sont presents a l'interieur des grains de poudre apres frittage. Pour les frittages en phase liquide, l'intensite de la diffusion

  18. One-step electrodeposition of a molecularly imprinting chitosan/phenyltrimethoxysilane/AuNPs hybrid film and its application in the selective determination of p-nitrophenol.

    Science.gov (United States)

    Li, Shanshan; Du, Dan; Huang, Jing; Tu, Haiyang; Yang, Yuqi; Zhang, Aidong

    2013-05-07

    This paper presents the fabrication of a molecularly imprinting sol-gel hybrid film by the one-step electrodeposition of the constitutional individuals including chitosan (CS), phenyltrimethoxysilane (PTMS), in situ formed gold nanoparticles (AuNPs) and template p-nitrophenol (p-NP). The electrodeposition was triggered by applying an optimal potential at -0.30 V vs. SCE, leading to the formation of the p-NP imprinting CS/PTMS/AuNPs hybrid film on a glassy carbon electrode (GCE) with a roughly architectural and conductive nature, as revealed by scanning electron microscopy and electrochemical impedance analysis. The mechanism of the hybrid film formation was discussed accordingly. Upon complete removal of the template molecules assisted by cyclic voltammetry, the p-NP imprinted film modified electrode exhibited differential pulse voltammetric (DPV) responses to p-NP in a linear range from 3.0 × 10(-8) to 3.5 × 10(-4) M with a detection limit of 5.0 × 10(-9) M. The selectivity and reusability of the sensor was demonstrated by discriminating the p-NP response from its analogues and successive rebinding/debinding cycles, respectively. The methodology is extendable as a simple and general platform for developing hybrid film sensors for the specific determination of various electrochemically active species.

  19. Development of casting investment preventing blackening of noble metal alloys part 1. Application of developed investment for Ag-Pd-Cu-Au alloy.

    Science.gov (United States)

    Kakuta, Kiyoshi; Nakai, Akira; Goto, Shin-ichi; Wakamatsu, Yasushi; Yara, Atushi; Miyagawa, Yukio; Ogura, Hideo

    2003-03-01

    The objective of this study is to develop a casting investment that prevents the blackening of the cast surface of noble metal alloys. The experimental investments were prepared using a gypsum-bonded investment in which the metallic powders such as boron (B), silicon (Si), aluminum (Al) and titanium (Ti) were added as oxidizing agents. An Ag-Pd-Cu-Au alloy was cast into the mold made of the prepared investment. The effect of the addition of each metal powder was evaluated from the color difference between the as-cast surface and the polished surface of the cast specimen. The color of the as-cast surface approached that of the polished surface with increasing B and Al content. A lower mean value in the color difference was obtained at 0.25-1.00 mass% B content. B and Al are useful as an additive in a gypsum-bonded investment to prevent the blackening of an Ag-Pd-Cu-Au alloy. The effects of Si and Ti powder addition could not be found.

  20. Intensity (a.u)

    Indian Academy of Sciences (India)

    Administrator

    Supplementary Information. Fig. S1. Powder X-ray diffraction pattern (Cu Kα) for AlPO-5: (a) as prepared, (b) calcined and (c) simulated [Ref. 27]. 10. 20. 30. 40. 50. Intensity (a.u) b c a. 2θ ...

  1. Au pairs on Facebook

    DEFF Research Database (Denmark)

    Dalgas, Karina Märcher

    2016-01-01

    that engagement with Facebook as a methodological tool can be useful in research among migrants in highly politicised fields. Pointing to a discursive construction of Filipina au pairs as victims of labour exploitation, the article shows how fieldwork on Facebook enables the exploration of the ways in which...

  2. Magnetic susceptibilities of liquid Cr-Au, Mn-Au and Fe-Au alloys

    Energy Technology Data Exchange (ETDEWEB)

    Ohno, S.; Shimakura, H. [Niigata University of Pharmacy and Applied Life Sciences, Higashijima, Akiha-ku, Niigata 956-8603 (Japan); Tahara, S. [Faculty of Science, University of the Ryukyus, Nishihara-cho, Okinawa 903-0213 (Japan); Okada, T. [Niigata College of Technology, Kamishin’eicho, Nishi-ku, Niigata 950-2076 (Japan)

    2015-08-17

    The magnetic susceptibility of liquid Cr-Au, Mn-Au, Fe-Au and Cu-Au alloys was investigated as a function of temperature and composition. Liquid Cr{sub 1-c}Au{sub c} with 0.5 ≤ c and Mn{sub 1-c}Au{sub c} with 0.3≤c obeyed the Curie-Weiss law with regard to their dependence of χ on temperature. The magnetic susceptibilities of liquid Fe-Au alloys also exhibited Curie-Weiss behavior with a reasonable value for the effective number of Bohr magneton. On the Au-rich side, the composition dependence of χ for liquid TM-Au (TM=Cr, Mn, Fe) alloys increased rapidly with increasing TM content, respectively. Additionally, the composition dependences of χ for liquid Cr-Au, Mn-Au, and Fe-Au alloys had maxima at compositions of 50 at% Cr, 70 at% Mn, and 85 at% Fe, respectively. We compared the composition dependences of χ{sub 3d} due to 3d electrons for liquid binary TM-M (M=Au, Al, Si, Sb), and investigated the relationship between χ{sub 3d} and E{sub F} in liquid binary TM-M alloys at a composition of 50 at% TM.

  3. Modélisation thermique d'une interface solide-fluide par fonction de transfert

    Science.gov (United States)

    Guigoures, Franck; Maye, Jean-Pierre; Garnier, Jean-Philippe

    A thermal modelling of a solid-fluid interface is proposed. The developed procedure is based on a numerical identification, in a dimensionless space, of a unique transfer function, associated with a recurrent relation. The method is usable for direct or inverse problems and well fit for control-command applications. An inverse numerical simulation example is presented for a random thermal excitation.

  4. Stability, structural and electronic properties of benzene molecule adsorbed on free standing Au layer

    Energy Technology Data Exchange (ETDEWEB)

    Katoch, Neha, E-mail: nehakatoch2@gmail.com; Kapoor, Pooja; Sharma, Munish; Ahluwalia, P. K. [Physics Department, Himachal Pradesh University, Shimla, Himachal Pradesh, India 171005 (India); Kumar, Ashok [Center for Physical Sciences, School of Basic and Applied Sciences, Central University of Punjab, Bathinda, India, 151001 (India)

    2016-05-23

    We report stability and electronic properties of benzene molecule adsorbed on the Au atomic layer within the framework of density function theory (DFT). Horizontal configuration of benzene on the top site of Au monolayer prefers energetically over other studied configurations. On the adsorption of benzene, the ballistic conductance of Au monolayer is found to decrease from 4G{sub 0} to 2G{sub 0} suggesting its applications for the fabrications of organic sensor devices based on the Au atomic layers.

  5. Development of Ag-Pd-Au-Cu alloy for multiple dental applications. Part 1. Effects of Pd and Cu contents, and addition of Ga or Sn on physical properties and bond with ultra-low fusing ceramic.

    Science.gov (United States)

    Goto, S; Miyagawa, Y; Ogura, H

    2000-09-01

    Ag-Pd-Au-Cu quaternary alloys consisting of 30-50% Ag, 20-40% Pd, 10-20% Cu and 20% Au (mother alloys) were prepared. Then 5% Sn or 5% Ga was added to the mother alloy compositions, and another two alloy systems (Sn-added alloys and Ga-added alloys) were also prepared. The bond between the prepared alloys and an ultra-low fusing ceramic as well as their physical properties such as the solidus point, liquidus point and the coefficient of thermal expansion were evaluated. The solidus point and liquidus point of the prepared alloys ranged from 802 degrees C to 1142 degrees C and from 931 degrees C to 1223 degrees C, respectively. The coefficient of thermal expansion ranged from 14.6 to 17.1 x 10(-6)/degrees C for the Sn- and Ga-added alloys. In most cases, the Pd and Cu contents significantly influenced the solidus point, liquidus point and coefficient of thermal expansion. All Sn- and Ga-added alloys showed high area fractions of retained ceramic (92.1-100%), while the mother alloy showed relatively low area fractions (82.3%) with a high standard deviation (20.5%). Based on the evaluated properties, six Sn-added alloys and four Ga-added alloys among the prepared alloys were suitable for the application of the tested ultra-low fusing ceramic.

  6. Application des règles protectrices relatives au logement familial à la résiliation d’un bail mixte (locaux commerciaux et logement de famille), sauf abus de droit: application de la théorie de la réception absolue à la résiliation du bail

    OpenAIRE

    Dietschy, Patricia

    2012-01-01

    Les règles spéciales applicables au logement de la famille doivent être respectées en cas de résiliation d’un bail à destination mixte (locaux commerciaux et logement familial), sous réserve d’abus de droit. La théorie de la réception absolue s’applique en matière de résiliation de bail (confirmation de jurisprudence).

  7. Effect of Silicon on Activity Coefficients of Siderophile Elements (P, Au, Pd, As, Ge, Sb, and In) in Liquid Fe, with Application to Core Formation

    Science.gov (United States)

    Righter, K.; Pando, K.; Danielson, L. R.; Humayun, M.; Righter, M.; Lapen, T.; Boujibar, A.

    2016-01-01

    Earth's core contains approximately 10 percent light elements that are likely a combination of S, C, Si, and O, with Si possibly being the most abundant. Si dissolved into Fe liquids can have a large effect on the magnitude of the activity coefficient of siderophile elements (SE) in Fe liquids, and thus the partitioning behavior of those elements between core and mantle. The effect of Si can be small such as for Ni and Co, or large such as for Mo, Ge, Sb, As. The effect of Si on many siderophile elements is unknown yet could be an important, and as yet unquantified, influence on the core-mantle partitioning of SE. Here we report new experiments designed to quantify the effect of Si on the partitioning of P, Au, Pd, and many other SE between metal and silicate melt. The results will be applied to Earth, for which we have excellent constraints on the mantle siderophile element concentrations.

  8. Mise en evidence de mouvements de sable a partir d'images satellitales ; application au piemont sud de l'atlas saharien(Algerie

    Directory of Open Access Journals (Sweden)

    ABDELLAOUI ABDELKADER

    2010-09-01

    Full Text Available La zone d’étude se localise au piémont sud de l’Atl as saharien (Algérie et concerne le site de la vil le de Laghouat et ses environs limitrophes. Les principaux éléments orogr aphiques sont représentés par Djebel Ahmar (883m a u Sud-Ouest, Djebel Oum Deloua (1023m au Nord-Ouest, formant un syncli nal perché, et un peu plus au Nord-Ouest le grand s ynclinal du Milok, de direction atlasique. Le principal cours d’eau qui t raverse la zone Est Oued M’zi d’orientation Nord-Ou est-Sud-Est, empruntant par la suite une direction globale sous-latitudinale, à p artir de l’extrémité Sud-Ouest du Djebel Oum Deloua . Son affluent le plus important est Oued Messaad, avec un écoulement Sud-Ouest-Nord -Est. Cette zone comprend différentes formes et formation s sableuses dont la disposition est tributaire des ensembles orographiques, de la topographie de détail et des d irections du transport éolien. La population de Laghouat, ville présaharienne, est passée d’environ 6000 habitants en 1830 à 42800 ha bitants en 1977 et à 119043 habitants en 2003, soit une variation d e 178% (c’est-à-dire une multiplication par un fact eur de 2,8 sur une période de 26 ans entre 1977 et 2003. L’extension du bâti, sous la pression des besoins croissants en logemen ts, arrive à l’heure actuelle aux limites des massifs avoisinants (dépôt s sableux sur les flancs et des zones inondables. Le sable constitue ainsi un facteur de risque permanent de plus en plus ressent i pour la santé publique, la qualité de vie, mais é galement un danger pour les zones de mise en valeur agricole, notamment du Mekh areg à l’Est de Laghouat. Il devient alors pertinen t de mettre au point un moyen de localisation et de surveillance de la d ynamique des édifices de sable dans la région. Les traitements conventionnels de l’image satellita le (compositions colorées, indices thématiques ne permettent pas de différencier correctement le voile sableux

  9. Resistance varietale de la luzerne au nematode des tiges Ditylenchus dipsaci (Kuhn) Filipjev. Test d'evaluation et application en selection

    OpenAIRE

    Leclercq, D.; Caubel, G.

    1991-01-01

    La résistance variétale à Ditylenchus dipsaci chez la luzerne est évaluée par un test de dépistage au stade plantule, fondé sur la caractérisation des symptômes exprimés après l’inoculation artificielle. La méthode employée présente certains facteurs de variabilité qui ont été étudiés. Ainsi, les symptômes à rechercher ont été précisés, les effets notateur et date de notation déterminés. Il n’a pas été décelé de «pathotypes» de nématodes se multipliant sur les génotypes habituellement rés...

  10. Développement d'une application de suivi de trajectoire : stage ingénieur du 2 mai au 17 août 2007

    OpenAIRE

    LABONNE, Sébastien; LABORATOIRE CENTRAL DES PONTS ET CHAUSSEES - LCPC; ECOLE CENTRALE DE NANTES

    2007-01-01

    Le projet RADARR s'inscrit dans la volonté d'améliorer la sécurité des routes en offrant aux gestionnaires un moyen de prévention des sites dangereux. Il vise particulièrement les routes secondaires qui enregistrent aujourd'hui encore un nombre élevé d'accidents mortels dus à l'état de la chaussée ou au manque de signalisation, notamment dans certains virages. L'objectif de ce projet consiste à déterminer la dangerosité d'un site en étudiant la vitesse des véhicules ainsi que leur trajectoire...

  11. Durabilité de joints adhésifs silicone sous conditions environnementales sévères : application au packaging en électronique de puissance

    OpenAIRE

    Gros, Céline

    2006-01-01

    Des méthodologies d'étude de la durabilité de systèmes collés existent. Elles consistent à optimiser les assemblages avant vieillissement dans un premier temps de sorte à obtenir des propriétés optimales du collage suivi de l’étude de l'adhérence au cours du vieillissement. En vieillissement, les matériaux à assembler ont montré une résistance remarquable. Puis, nous avons étudié l'adhérence de ces systèmes par l’utilisation d’un test spécifique indiquant une diminution importante de l'adhére...

  12. Les technolectes au Maroc

    OpenAIRE

    Messaoudi, Leila

    2017-01-01

    Cette réflexion sur les technolectes au Maroc émane d’un ensemble de travaux menés sur le terrain et conduit à une synthèse permettant de dégager le fonctionnement général et les tendances d’évolution. Nous commencerons par rappeler les traits définitoires du technolecte. Nous aborderons ensuite se : modes de réalisation, en illustrant par des échantillons de corpus recueillis au Maroc. Définition de « technolecte » Par « technolecte », nous entendons l’ensemble des usages lexicaux et discurs...

  13. Le CRDI au Cambodge

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

    Le CRDI a été l'un des premiers bailleurs de fonds à établir des relations avec le Cambodge au début des années 1990, alors que le pays progres- sait vers la paix. Depuis, le Centre aide à reconstruire le Cambodge, qui se remet du régime inhumain des Khmers rouges et de décennies de conflits régionaux. Un État ...

  14. Le CRDI au Vietnam

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

    des agriculteurs trouvent des solutions de rechange à la culture du tabac. □ des responsables de politiques agissent pour réduire la pauvreté. Soutien accordé par le CRDI depuis 1991. 111 activités d'une valeur de 30 millions cad. CRDI. Le CRDI au Vietnam centre de recherches pour le développement international ...

  15. Mise au point

    African Journals Online (AJOL)

    7 mai 2012 ... cervico-thoracique confirme l'existence d'un goitre plon- geant aux dépens du lobe droit restant à 15 mm de la crosse aortique associé à un processus expansif tissulai- ... DU CANCER DIFFERENCIE DE LA ThYROIDE. R. BEN M'hAMED et al. Journal ORL N°26 .ai:Mise au point 07/05/12 09:45 page54 ...

  16. Le CRDI au Ghana

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

    pour prévenir le paludisme, des études ayant démontré que leur utilisation pouvait réduire considérablement la mortalité infantile. Les chercheurs ont également suggéré aux gouvernements différents moyens pour inciter les gens à acheter les moustiquaires et à les utiliser correctement. Les TI au service de la démocratie.

  17. Mise au point

    African Journals Online (AJOL)

    31 mai 2013 ... volumineuse tuméfaction sus claviculaire. Cette masse intéressant toute la partie latérale droite du cou et le quart supérieur du thorax était indolore, mobile par rapport au plan profond et rénitente mesurant 22 cm sur 26 cm de diamètre. On notait la présence de lacis veineux. ailleurs, les poumons étaient ...

  18. Le CRDI au Maroc

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

    démocratiques. Au Maroc, le Centre d'études et de recherches en sciences sociales analyse ce que pourrait être la réaction du gouverne- ment aux pressions exercées par la population en vue d'un changement sur le plan politique. Rabat. Casablanca. Marrakech. Tan-Tan. Bou Arfa. Zagora. Oujda. Tanger. Fès. ALGÉRIE.

  19. Mise au point

    African Journals Online (AJOL)

    et traité à temps, le risque de complications et de morbidité peut être écarté. Les auteurs rapportent 2 cas de kystes de la vallécule. La tomodensitométrie a confirmé la présence d'une formation kystique prenant origine au niveau de la val- lécule. Une laryngoscopie directe a été faite pour les 2 patients sous anesthésie ...

  20. Pratique de la science sociale au maghreb: l'approche intercontextuelle de la modernité

    Directory of Open Access Journals (Sweden)

    Z. Samandi

    2002-12-01

    Full Text Available L'étude pose le problème du statut scientifique de la pratique du chercheur en science sociale dans les contextes non producteurs de savoir. Comment opérer avec des formes de savoir produites ailleurs? Telle est la question que nous avons essayé de décrypter à travers les débats développés, d'une part par les sociologues arabes et, d'autre part l'approche mise en œuvre par Arkoun, Djaït et El Jabri dans leur analyse des réalités arabo-musulmanes. Le traitement de la raison tel qu'il se donne à voir à travers les démarches examinées met au jour la pertinence de la médiation contextuelle qui ne peut se réduire à un simple transfert des outils d'analyse. L'intercontextualité comme pratique est de la sorte induite par le travers de décontextualisation-recontextualisation opéré à l'intérieur du champ de la recherche. Elle est inscrite en creux dans l'exercice d'analyse et se présente à la fois comme dimension épistémologique et herméneutique.

  1. Isolation and characterization of the tertiary amine Alamine 304 hydrochioride. Its application on the extraction of Co(II, Au(III and Pt(IV

    Directory of Open Access Journals (Sweden)

    López-Delgado, Aurora

    2000-06-01

    Full Text Available Amine Alamine 304 dissolved in xylene reacts with hydrochloric acid to form the amine chloride (R3NH+Cl- and the amine dichloride (R3NH2Cl2. The former compound was isolated and characterized by chemical analysis, X-ray powder diffraction, infrared spectroscopy and scanning electron microscopy. Lattice parameters of the isolated amine chloride were determined and refined by least-square numerical treatment (monoclinic cell, with a = 29.017(4 Å, b = 14.564(7 Å, c = 5.043(1 Å, b = 95.68(3 ° and V = 2,120 Å3. The amine chloride is a potential anion-exchanger with metals, thus data on the liquid-liquid extraction of Co(II, Au(III and Pt(IV are also reported.

    La amina Alamine 304 disuelta en xileno reacciona con el ácido clorhídrico para formar el cloruro de la amina (R3NH+Cl- y el dicloruro de amina (R3NH2Cl2. El primero de estos compuestos se aisló y caracterizó mediante análisis químico, difracción de rayos X, espectroscopia de IR y microscopía electrónica de barrido. Se determinaron y refinaron los parámetros de red del cloruro de amina (monoclínico, a = 29,017(4 Å, b = 14,564(7 Å, c = 5,043(1 Å, b = 95,68(3 ° y V = 2.120 Å3. El cloruro de amina actúa como un intercambiador aniónico con ciertos metales, por lo que se incluyen datos sobre la extracción líquido-líquido de Co(II, Au(III y Pt(IV.

  2. Tourisme et communautés rurales au Venezuela : vers une application des principes du Développement Durable

    Directory of Open Access Journals (Sweden)

    Olivier Dehoorne

    2008-02-01

    Full Text Available L’évolution récente du tourisme international au Venezuela est particulièrement intéressante : l'activité touristique qui reste très largement concentrée sur la côte caribéenne, et notamment l’île de Margarita, se diversifie au profit de nouveaux centres d’intérêt dans les régions intérieures. L’affichage de nouvelles volontés politiques sur la scène régionale et internationale, sous l’impulsion du président Chavez, a perturbé le marché touristique national qui était dominé pour les clientèles nord-américaines ; le Venezuela apparaît désormais aux yeux des Etats-Unis comme un pays à risque, instable. C’est dans ce contexte que s’inscrit le « Programa Andes Tropicales » [PAT] qui soutient le  développement rural dans les parcs nationaux ; ce programme repose sur la participation des populations locales et leur implication dans les politiques de conservation des ressources naturelles et culturelles sources de revenus. Le soutien financier des microprojets familiaux et communautaires doivent permettent de lutter contre la pauvreté.The recent evolution of international tourism in Venezuela is particularly interesting. Even if tourism activity remains heavily concentrated on the Caribbean coast, in particular on the island of Margarita, it is nevertheless diversifying gradually to make way for new areas of interest in the country’s interior. The display of new political will on the regional and international scene, under the leadership of President Chavez, has disrupted the national tourism market which was dominated by North American customers. Venezuela now appears in the eyes of the United States as a country that is at risk,and therefore unstable. It is in this context that the “Programa Andes Tropicales" [PAT] was developed to promote rural development in national parks; This program is based on the participation and involvement of local populations in the development of appropriate

  3. Thermal transfers in thermo-capillary convection; Transferts thermiques en convection thermocapillaire

    Energy Technology Data Exchange (ETDEWEB)

    Hoo, B. [Institut National des Sciences et Techniques Nucleaires (INSTN) - Centre d`Etudes Nucleaires de Saclay, 91 - Gif-sur-Yvette (France)]|[Universite de Versailles, 78 - Versailles (France)

    1997-12-31

    This report is devoted to the S.I.L.V.A. process, (Isotope Separation by Laser of Atomic Vapors) developed by the Cea for uranium enrichment. one problem met with it, is this one of the evaporation rate, that determines the technique performance. The evaporation rate is not a linear function of the heat power. Taking into account of limits conditions that the liquid bath undergoes it has been estimated that the thermo gravity and the thermo-capillary convection that takes place, absorbs at least the half power necessary to the evaporation. So, here is studied the thermo-hydraulics of a liquid bath model put down a heating concentrated on its free surface. Little viscous oil is used as work liquid. This study concerns the S.I.L.V.A. process but it can have an interest for others applications as welding or crystal growth. (N.C.).

  4. Surface-enhanced Raman spectroscopy with Au-nanoparticle substrate fabricated by using femtosecond pulse

    Science.gov (United States)

    Zhang, Wending; Li, Cheng; Gao, Kun; Lu, Fanfan; Liu, Min; Li, Xin; Zhang, Lu; Mao, Dong; Gao, Feng; Huang, Ligang; Mei, Ting; Zhao, Jianlin

    2018-05-01

    Au-nanoparticle (Au-NP) substrates for surface-enhanced Raman spectroscopy (SERS) were fabricated by grid-like scanning a Au-film using a femtosecond pulse. The Au-NPs were directly deposited on the Au-film surface due to the scanning process. The experimentally obtained Au-NPs presented local surface plasmon resonance effect in the visible spectral range, as verified by finite difference time domain simulations and measured reflection spectrum. The SERS experiment using the Au-NP substrates exhibited high activity and excellent substrate reproducibility and stability, and a clearly present Raman spectra of target analytes, e.g. Rhodamine-6G, Rhodamine-B and Malachite green, with concentrations down to 10‑9 M. This work presents an effective approach to producing Au-NP SERS substrates with advantages in activity, reproducibility and stability, which could be used in a wide variety of practical applications for trace amount detection.

  5. Interfacial microstructures and kinetics of Au/SnAgCu

    International Nuclear Information System (INIS)

    Lee, Teck Kheng; Zhang, Sam; Wong, C.C.; Tan, A.C.; Hadikusuma, Davin

    2006-01-01

    The gold/lead-free solder system, or Au/SnAgCu is a potential flip chip interconnect solutions for fine-pitch applications. This paper studies the interfacial microstructures and initial isothermal solid-liquid interdiffusion kinetics during the first 3 s of bonding at 230-290 deg. C. As revealed by Scanning Electron Microscopy (SEM), different morphologies of AuSn, AuSn 2 and AuSn 4 are observed under different bonding conditions. The initial Au-Sn solid/liquid interdiffusion kinetics is discussed with respect to its microstructures. The rate of Au consumption is used as a measure of the rate of intermetallic compound (IMC) formation. The fitted power law relationship reveals kinetically that Au consumption follows the Arrhenius relationship with a time exponent of 0.5. Isothermal aging at temperatures between 125 deg. C and 165 deg. C gives rise to activation energies and the rate of Au consumption in solid-liquid interdiffusion to be two orders of magnitude faster than solid interdiffusion

  6. Stability of gold cages (Au16 and Au17) at finite temperature

    Indian Academy of Sciences (India)

    a promising chemical catalyst [4–6]. Owing to such potential applications, a large amount of experimental [7–11] and theoretical [12–20] work probing structural and electronic properties of Au clusters has been reported. These reports reveal that the ground state (GS) geometries of gold clusters with sizes up to a few tens of ...

  7. Mise au point d'un Système d'Information Géographique (SIG), à l'échelle de la parcelle, pour l'évaluation du risque de pollution des eaux de surface et souterraines par l'usage des pesticides.

    OpenAIRE

    Bah, Boubacar Billo; Limbourg, Quentin; Vandendael, Laurent; Huyghebaert, Bruno; Oger, Robert

    2012-01-01

    L’étude aborde la mise au point d’un outil SIG décisionnel, basé sur une approche « expert » par logique floue, pour l’évaluation du risque de pollution des eaux de surface et souterraines par les pesticides. Une enquête de terrain combinée aux propriétés physico-chimiques des pesticides, a permis d’identifier la pression polluante agricole liée aux propriétés des pesticides et aux activités anthropiques. La sensibilité des sols au transfert des pesticides vers les eaux de surface et soute...

  8. Application of modified multiwalled carbon nanotubes as a sorbent for simultaneous separation and preconcentration trace amounts of Au(III) and Mn(II)

    International Nuclear Information System (INIS)

    Shamspur, Tayebeh; Mostafavi, Ali

    2009-01-01

    A solid phase extraction procedure is proposed for simultaneous separation and preconcentration trace amounts of Au(III) and Mn(II) in an aqueous medium by using a column of multiwalled carbon nanotubes modified with the analytical reagent N,N'-bis(2-hydroxybenzylidene)-2,2'(aminophenylthio)ethane. An implementation, it was found that the sorption is quantitative in the pH range 5.0-7.5, whereas quantitative desorption occurs instantaneously with 4.0 mL of 0.1 mol L -1 Na 2 S 2 O 3. Selected elements were also determined by flame atomic absorption spectrometry. Linearity was maintained between 0.2 ng mL -1 to 25 μg mL -1 for gold and 0.08 ng mL -1 to 5 μg mL -1 for manganese in the original solution. Various parameters such as the effect of pH, flow rate, type and amount of eluent, breakthrough volume and interference of a large number of anions and cations on the recovery of the selected ions was studied. Under optimum conditions, the detection limits (3 s, n = 10) for analytes were 0.03 ng mL -1 (gold) and 0.01 ng mL -1 (manganese). The method was successfully applied for separation and determination of gold and manganese ions in water and standard samples.

  9. Etude du transfert thermique conjugue dans les cavites rectangulaires en convection naturelle

    Science.gov (United States)

    Nouanegue, Herve Frank

    Energy conservation is one of the most important areas of research and development. In parallel and in conjunction with it, developing clean energy technologies using renewable energy sources is similarly an important area to provide a sustainable energy supply. In this way, the quality of life will continue to flourish and at the same time the environment will be protected. For this purpose, devices operating on the principal of passive utilization techniques are used in different applications such as solar collectors, passive cooling and heating of buildings and others. Many of these applications make use of open and/or closed enclosures having different geometries, in which heat transfer by natural convection is used often with conjunction of conduction and surface radiation. To have the best thermal performance of these devices, the understanding of conjugate heat transfer in basic geometries is essential. The aim of this thesis is to study the influence of conduction and radiation heat transfer on natural convection in rectangular enclosures with different geometries and properties. A mathematical model of the system is developed which combines heat transfer by convection, conduction and radiation. A numeric code based on the volume control method is developed to simulate open and close systems with different geometries, in which the conservation equations of mass, momentum and energy are solved using the control volume method and the radiation heat exchange equations are added by calculating radiative heat flux on the emitting surfaces and treating it as a local heat source for the conjugate heat transfer by the three modes. Four specific configurations have been studied. The first one is a closed square inclined cavity containing a massive wall. The second configuration is an open cavity. The last two configurations involve passive cooling and heating systems in which the air circulates in long vertical channels. Numerical results for all the configuration

  10. MECANISME DE TRANSFERT DE PROTON ENTRE LES ACIDES ACETIQUE, TRIFLUOROACETIQUE ET L'ANHYDRIDE ACETIQUE. MISE EN EVIDENCE D'IONS ANHYDRIDIUM ET ACIDIUM ACETIQUES

    OpenAIRE

    A BOUCHOUL; P PAILLOUS; D ROUAG; S.E BOUAOUD

    2000-01-01

    L'analyse spectroscopique par infrarouge et Raman de l'interaction de l'acide acétique avec l'anhydride correspondant montre l'existence d'un équilibre de protonation de ce dernier avec formation d'une entité protonée relativement stable sous forme de chélate cyclique:  l'ion anhydridium acétique.      Une étude analogue portant sur le phénomène de transfert de proton entre les acides acétique et trifluoroacétique révèle la formation d'ions acidiums acétiques sous forme ouverte.          ...

  11. Evolution du génome des Streptomyces : transfert horizontal et variabilité des extrémités chromosomiques

    OpenAIRE

    Choulet, Frédéric

    2006-01-01

    L'analyse et la comparaison des génomes permettent d'appréhender les forces évolutives à la base de leur dynamique et les contraintes qui s'opposent à la variabilité. Chez les bactéries, le transfert horizontal joue un rôle majeur dans leur diversification. Ce travail traite de l'évolution du génome des Streptomyces qui sont des bactéries du sol responsables de la biosynthèse d'une très grande diversité de composés actifs. Leur intérêt applicatif est considérable et touche des domaines variés...

  12. L’olivier au Maroc

    Directory of Open Access Journals (Sweden)

    El Mouhtadi Issam

    2014-03-01

    Full Text Available L’olivier est une culture traditionnelle sur le pourtour de la Méditerranée. Il est donc naturel de trouver cet arbre au Maroc où il est présent depuis des siècles. Cultivé surtout traditionnellement jusqu’à ses dernières années, il fait l’objet maintenant d’un plan de valorisation très ambitieux pour non seulement garder le Royaume à son niveau actuel (2e producteur mondial pour l’olive de conserve et 6e pour l’huile d’olive mais pour conquérir de nouveaux marchés au niveau mondial et profiter ainsi de l’engouement que connaît cette huile reconnue pour ses bienfaits. Le plan national « Maroc Vert » permet ainsi, grâce à des subventions conséquentes, non seulement de renouveler les vergers existant avec la variété traditionnelle picholine du Maroc, mais également la plantation de nouvelles variétés en super-intensif dans le but d’industrialiser au maximum de nouveaux vergers. Il en est de même pour la transformation des olives en huile de bonne qualité avec la mise en place d’unités de trituration modernes qui doivent supplanter à terme la multitude de « maâsra » et réduire ainsi l’impact environnemental dû aux margines. L’olive ne sera plus dans l’avenir que représentée par son huile et ses formes comestibles, mais les résidus de son extraction seront valorisés soit sous forme de combustible élaboré pour le grignon, soit sous forme d’une base de chimie verte pour les sous-produits du raffinage. D’autres applications sont actuellement à l’étude, car le Maroc à compris, comme tous les autres grands pays producteurs, que l’olive était un nouveau gisement de richesses.

  13. Mise au point

    African Journals Online (AJOL)

    tomie est replacé et fixé par des fils d'acier, krönlein lais- sait ce fragment pédiculé au fascia temporalis afin d'évi- ter la dépression de la fosse temporale due à la désinser- tion du muscle temporal [20] ; dans notre série, après reconstitution du cadre, le muscle temporal est suturé à son point d'insertion. pour les tumeurs ...

  14. Migration malienne au Cameroun

    OpenAIRE

    Cisse, Pierre

    2013-01-01

    L’attractivité économique du Cameroun à partir des années quatre-vingt a drainé une population d’émigrés maliens. S’appuyant sur un système efficace de réseaux de parenté, la communauté malienne du Cameroun assure sa propre pérennité. En offrant systématiquement un emploi au membre nouvellement venu, elle s’annexe des pans entiers de l’économie camerounaise. Ce faisant, à Yaoundé ou à Douala, elle se met aussi à dos une population autochtone concurrente.

  15. Mise au point

    African Journals Online (AJOL)

    31 mai 2013 ... L'attitude théra- peutique dépend du type de la laryngocèle. en effet, le traitement endoscopique au laser CO2 a gagné beaucoup d'intérêt ces dernières années. MATÉRIEL ET MÉTHOdES. Il s'agit d'une étude rétrospective portant sur 9 patients porteurs d'une laryngocèle colligés sur une période de 14.

  16. Le paludisme au Mexique

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

    Nancy Minogue

    Le paludisme est depuis longtemps un important problème de santé publique au Mexique, où les conditions qui prévalent ... C'est dans les régions côtières que le problème a persisté le plus longtemps, les mesures ... recherche sur l'écologie des moustiques a permis d'en découvrir les raisons. « Les moustiques ne se ...

  17. Charge transport through O-deficient Au-MgO-Au junctions

    KAUST Repository

    Fadlallah, M. M.

    2009-12-29

    Metal-oxide heterostructures have been attracting considerable attention in recent years due to various technological applications. We present results of electronic structure and transport calculations for the Au-MgO-Au (metal-insulator-metal) heterostructure based on density-functional theory and the nonequilibrium Green’s functions method. The dependence of the conductance of the heterostructure on the thickness of the MgO interlayer and the interface spacing is studied. In addition, we address the effects of O vacancies. We observe deviations from an exponentially suppressed conductance with growing interlayer thickness caused by Au-O chemical bonds. Electronic states tracing back to O vacancies can increase the conductance. Furthermore, this effect can be enhanced by enlarging the interface spacing as the vacancy induced Mg states are shifted toward the Fermi energy.

  18. Practical application of biological variation and Sigma metrics quality models to evaluate 20 chemistry analytes on the Beckman Coulter AU680.

    Science.gov (United States)

    Tran, Mai Thi Chi; Hoang, KienTrung; Greaves, Ronda F

    2016-11-01

    This study aimed to evaluate the imprecision and bias data generated for 20 routine chemistry analytes against both the biological variation fitness for purpose (FFP) and Sigma metrics (SM) criteria. Twenty serum/plasma analytes were evaluated on the Beckman Coulter AU680. Third party commercial lyophilized internal quality control samples of human origin were used for day-to-day imprecision calculations. Commercial external quality assurance (EQA) samples were used to determine the systematic error between the test method result and the instrument group mean result from the EQA program for each analyte. Biological variation data was used to calculate the minimum, desirable and optimal imprecision and bias for determination of FFP. The desirable total allowable error was determined from biological variation data and applied to the SM calculation. The outcomes of both quality approaches were then compared. The day-to-day imprecision of most tested analytes (except sodium and chloride) were smaller than the allowable imprecision (ranging from minimum to optimum). Most analytes achieved at least minimum bias. The SM varied with analyte concentration with six analytes producing low Sigma values. Comparing the quality processes eleven analytes produced a green light for both FFP and SM. There was some difference seen in interpretation for the other nine analytes. The individual interpretation of bias and imprecision using FFP criteria allowed for the clear determination of the major source of error. Whereas, SM provided a summative evaluation of method performance. But the selection of total allowable error (TEa) is fundamental to this interpretation and harmonisation of the TEa calculation is needed. Copyright © 2016 The Canadian Society of Clinical Chemists. Published by Elsevier Inc. All rights reserved.

  19. Optimizing the planar structure of (1 1 1) Au/Co/Au trilayers

    International Nuclear Information System (INIS)

    Kumah, D P; Cebollada, A; Clavero, C; Garcia-MartIn, J M; Skuza, J R; Lukaszew, R A; Clarke, R

    2007-01-01

    Au/Co/Au trilayers are interesting for a range of applications which exploit their unusual optical and electronic transport behaviour in a magnetic field. Here we present a comprehensive structural and morphological study of a series of trilayers with 0-7 nm Co layer thickness fabricated on glass by ultrahigh vacuum vapour deposition. We use a combination of in situ electron diffraction, atomic force microscopy and x-ray scattering to determine the optimum deposition conditions for highly textured, flat and continuous layered structures. The 16 nm Au-on-glass buffer layer, deposited at ambient temperature, is found to develop a smooth (1 1 1) texture on annealing at 350 deg. C for 10 min. Subsequent growth of the Co layer at 150 deg. C produces a (1 1 1) textured film with lateral grain size of ∼150 nm in the 7 nm-thick Co layer. A simultaneous in-plane and out-of-plane Co lattice expansion is observed for the thinnest Co layers, converging to bulk values for the thickest films. The roughness of the Co layer is similar to that of the Au buffer layer, indicative of conformal growth. The 6 nm Au capping layer smoothens the trilayer surface, resulting in a surface roughness independent of the Co layer thickness

  20. Optimizing the planar structure of (1 1 1) Au/Co/Au trilayers

    Energy Technology Data Exchange (ETDEWEB)

    Kumah, D P [Applied Physics Program and FOCUS Center, University of Michigan, 450 Church St., Ann Arbor, MI 48109-1040 (United States); Cebollada, A [Applied Physics Program and FOCUS Center, University of Michigan, 450 Church St., Ann Arbor, MI 48109-1040 (United States); Clavero, C [Instituto de Microelectronica de Madrid-IMM (CNM-CSIC), Isaac Newton 8-PTM, 28760 Tres Cantos, Madrid (Spain); Garcia-MartIn, J M [Instituto de Microelectronica de Madrid-IMM (CNM-CSIC), Isaac Newton 8-PTM, 28760 Tres Cantos, Madrid (Spain); Skuza, J R [Physics and Astronomy Department, University of Toledo, 2801 W. Bancroft St., Mailstop 111, Toledo, OH 43606 (United States); Lukaszew, R A [Physics and Astronomy Department, University of Toledo, 2801 W. Bancroft St., Mailstop 111, Toledo, OH 43606 (United States); Clarke, R [Applied Physics Program and FOCUS Center, University of Michigan, 450 Church St., Ann Arbor, MI 48109-1040 (United States)

    2007-05-07

    Au/Co/Au trilayers are interesting for a range of applications which exploit their unusual optical and electronic transport behaviour in a magnetic field. Here we present a comprehensive structural and morphological study of a series of trilayers with 0-7 nm Co layer thickness fabricated on glass by ultrahigh vacuum vapour deposition. We use a combination of in situ electron diffraction, atomic force microscopy and x-ray scattering to determine the optimum deposition conditions for highly textured, flat and continuous layered structures. The 16 nm Au-on-glass buffer layer, deposited at ambient temperature, is found to develop a smooth (1 1 1) texture on annealing at 350 deg. C for 10 min. Subsequent growth of the Co layer at 150 deg. C produces a (1 1 1) textured film with lateral grain size of {approx}150 nm in the 7 nm-thick Co layer. A simultaneous in-plane and out-of-plane Co lattice expansion is observed for the thinnest Co layers, converging to bulk values for the thickest films. The roughness of the Co layer is similar to that of the Au buffer layer, indicative of conformal growth. The 6 nm Au capping layer smoothens the trilayer surface, resulting in a surface roughness independent of the Co layer thickness.

  1. Fe{sub 3}O{sub 4}@SiO{sub 2}–SO{sub 3}H@PPy@Au spheres: Fabrication, characterization and application in SERS

    Energy Technology Data Exchange (ETDEWEB)

    Ren, Guohong; Shang, Mengying; Zou, Hanzhi; Wang, Wenqin, E-mail: wangwenqin@nbu.edu.cn

    2016-04-15

    In this work, the sulfonic acid (–SO{sub 3}H) group terminated Fe{sub 3}O{sub 4}@SiO{sub 2} magnetic spheres were prepared. Polypyrrole (PPy) was in-situ polymerized on Fe{sub 3}O{sub 4}@SiO{sub 2}–SO{sub 3}H spheres due to the dual roles of the –SO{sub 3}H groups: acting as both “anchoring sites” for adsorbing of pyrrole monomer and dopant agent in PPy. By adsorbing gold nanoseeds on the as-prepared Fe{sub 3}O{sub 4}@SiO{sub 2}–SO{sub 3}H@PPy spheres followed the seed-mediated growth method, the multifunctional Fe{sub 3}O{sub 4}@SiO{sub 2}–SO{sub 3}H@PPy@Au spheres were obtained. The application of Fe{sub 3}O{sub 4}@SiO{sub 2}–SO{sub 3}H@PPy@Au spheres in surface-enhanced Raman scattering (SERS) was investigated, and the results exhibited the enhancement in the order of 10{sup 4} using 4-aminothiophenol as the probe molecule. - Highlights: • The sulfonic acid-terminated Fe{sub 3}O{sub 4}@SiO{sub 2} (Fe{sub 3}O{sub 4}@SiO{sub 2}–SO{sub 3}H) spheres were prepared. • The –SO{sub 3}H groups of Fe{sub 3}O{sub 4}@SiO{sub 2}–SO{sub 3}H spheres played dual roles in adsorbing pyrrole and protonating polypyrrole. • Fe{sub 3}O{sub 4}@SiO{sub 2}–SO{sub 3}H@PPy core/gold shell composites can act as SERS substrate for detecting 4-ATP molecule.

  2. Charged particle density distributions in Au+ Au collisions at ...

    Indian Academy of Sciences (India)

    Charged particle pseudorapidity distributions have been measured in Au + Au collisions using the BRAHMS detector at RHIC. The results are presented as a function of the collision centrality and the center of mass energy. They are compared to the predictions of different parton scattering models and the important role of ...

  3. Charged particle density distributions in Au + Au collisions at ...

    Indian Academy of Sciences (India)

    Charged particle pseudorapidity distributions have been measured in Au + Au collisions using the BRAHMS detector at RHIC. The results are presented as a function of the collision centrality and the center of mass energy. They are compared to the predictions of different parton scattering models and the important role of ...

  4. Enhanced middle-infrared light transmission through Au/SiO(x)N(y)/Au aperture arrays.

    Science.gov (United States)

    Xiao, Gongli; Yao, Xiang; Ji, Xinming; Zhou, Jia; Bao, Zongming; Huang, Yiping

    2011-12-01

    The enhanced middle-infrared light transmission through Au/SiO(x)N(y)/Au aperture arrays by changing the refractive index and the thickness of a dielectric layer was studied experimentally. The results indicated that the transmission spectra was highly dependent on the refractive index and the thickness of SiO(x)N(y). We found that the transmission peaks redshifted regularly along with the refractive index from 1.6 to 1.8, owing to the role of surface plasmon polaritons (SPP) coupling in the Au/SiO(x)N(y)/Au cascaded metallic structure. Simultaneously, a higher transmission efficiency and narrower transmission peak was obtained in Au/SiO2.1N0.3/Au cascaded metallic structure with small refractive index (1.6) than in Au/SiO0.6N1/Au cascaded metallic structure with large refractive index (1.8). When the thickness of SiO(x)N(y) changes from 0.2 to 0.4 microm, the shape of transmission spectra exhibits a large change. It was found that a higher transmission efficiency and narrower transmission peak was obtained in Au/SiO(x)N(y)/Au cascaded metallic structure with a thin dielectric film (0.2 microm), with the increase of SiO(x)N(y) film's thickness, the transmission peak gradually widened and disappeared finally. This effect is useful in applications of biochemical sensing and tunable integrated plasmonic devices in the middle-infrared region.

  5. Studies of the structure and phase transitions of nano-confined pentanedithiol and its application in directing hierarchical molecular assemblies on Au(1 1 1)

    Science.gov (United States)

    Pawlicki, Alison; Avery, Erin; Jurow, Matthew; Ewers, Bradley; Vilan, Ayelet; Drain, Charles Michael; Batteas, James

    2016-03-01

    Directing molecular devices into pre-designed integrated electronic circuits while enforcing selectivity and hierarchy is an inherent challenge for molecular electronics. Here we explore ways to direct the assembly of electrically-active molecular monolayers into specific locations as well as controlling their internal organization. We have accomplished this by two consecutive surface reactions: (1) forming pentanedithiol (C5DT) domains within an inert alkanethiol self-assembled monolayer (SAM) on Au; and (2) selectively binding porphyrin derivatives to the C5DT domains. The C5DT domains were fabricated by phase segregation during co-adsorption from a mixed C5DT/dodecanethiol (C12) solution and nanografting with Atomic Force Microscopy (AFM). AFM revealed that co-absorbed and nanografted C5DT domains were in a standing-up phase and scanning tunneling microscopy (STM) showed that their molecular organization within about 5 nm, 40 nm, 50 nm and 120 nm domains, was dependent upon the size of the domain, such that structure of the C5DT transitions from (\\sqrt{3}   ×  \\sqrt{3} ) R30°, to (2  ×  2), and ultimately to a disordered phase with increasing domain size. This is due to the varying degrees of influence of the surrounding C12; providing sufficient van der Waals interactions as well as a geometric confinement to stabilize the standing-up phase of the C5DT. Understanding the molecular configuration of dithiol SAMs affords their use as a reactive template to subsequently bind active head groups. As a proof of principle, porphyrins with a pendant pentafluorophenyl ring were attached to the C5DT domains by a ‘click’ reaction between the fluorinated ring and the free thiol on the surface. From AFM and STM, these porphyrin derivatives reacted selectively with the C5DT domains with some porphyrins binding directly to the C5DT, subsequently allowing additional localized porphyrin deposition through pi-stacking.

  6. Developing an aqueous approach for synthesizing Au and M@Au (M = Pd, CuPt) hybrid nanostars with plasmonic properties

    OpenAIRE

    Du, Jingshan; Yu, Junjie; Xiong, Yalin; Lin, Zhuoqing; Zhang, Hui; Yang, Deren

    2014-01-01

    Anisotropic Au nanoparticles show unique localized surface plasmon resonance (LSPR) properties, which make it attractive in optical, sensing, and biomedical applications. In this contribution, we report a general and facile strategy towards aqueous synthesis of Au and M@Au (M = Pd, CuPt) hybrid nanostars by reducing HAuCl4 with ethanolamine in the presence of cetyltrimethylammonium bromide (CTAB). According to electron microscopic observation and spectral monitoring, we found that the layered...

  7. Mesure et modélisation multidimensionnelle des transferts thermiques gaz-paroi dans le cas des moteurs à allumage commandé Measurement and Multidimensional Modeling of Gas-Wall Heat Transfers in Spark-Ignition Engines

    Directory of Open Access Journals (Sweden)

    Gilaber P.

    2006-11-01

    Full Text Available A cette fin, deux étapes de recherche ont été mises en oeuvre : une phase expérimentale et une phase calcul. Dans la phase expérimentale, des mesures ont été faites sur un moteur monocylindre équipé de flux-mètres à réponse rapide. Chaque flux-mètre est composé d'un cylindre d'acier, contenant deux thermocouples. Dans le but de montrer l'influence de l'aérodynamique sur les échanges thermiques, un anémomètre à Laser a été utilisé à l'aide d'une entretoise placée entre culasse et cylindre. L'entretoise comportait deux hublots et deux flux-mètres permettant la mesure simultanée des flux thermiques et des paramètres aérodynamiques à l'extérieur de la couche limite. Deux flux-mètres supplémentaires ont été placés dans la culasse et le système d'acquisition permettait d'enregistrer simultanément dix voies de mesure à chaque degré vilebrequin, parmi lesquelles deux composantes de vitesse et la pression cylindre. Une étude paramétrique a révélé les tendances suivantes : - les pertes globales aux parois au cours d'un cycle thermodynamique diminuent lorsque le régime augmente, mais la valeur maximale des flux locaux augmente en raison de l'élévation du niveau de turbulence; - le remplissage a peu d'effet sur l'aérodynamique; son influence sur les transferts thermiques est due principalement à l'augmentation de la densité des gaz, qui se traduit par une augmentation des flux. Dans la phase calcul, deux idées de base ont guidé notre travail : - pour des raisons de temps de calcul prohibitif, il est impossible de mailler la couche limite; les échanges thermiques ont donc été estimés à l'aide d'une loi de paroi; - on fait l'hypothèse que les champs locaux de densité, vitesse et turbulence conditionnent fortement les flux thermiques; ce seront les paramètres de la loi de paroi. Dans cet esprit, le modèle de transferts thermiques de DIWAKAR a été introduit dans le code multi-dimensionnel KIVA. Une

  8. Une méthode pour estimer l’interception du rayonnement par un couvert bas : application au colza avant montaison

    Directory of Open Access Journals (Sweden)

    Denoroy Pascal

    2002-01-01

    introduire dans l’équation 2 un paramètre représentant le taux de couverture du sol. Si l’estimation par mesure directe de epsiloni et donc l’estimation de k sont assez simples, au moins dans le principe pour un couvert développé en hauteur (colza après montaison [3], une telle mesure devient beaucoup plus complexe dans le cas d’un couvert discontinu et bas. Dans ce milieu hétérogène (et souvent dans des conditions hivernales sévères, une distribution représentative des capteurs de rayonnement est difficile, les risques de perturbation de la mesure (salissure des capteurs, déréglages sont élevés. Plusieurs études ont déjà traité de epsiloni et k dans le cas du colza [3-7]. Elles sont fondées sur des mesures d’interception du rayonnement et concernent des couverts fermés, après montaison. Une autre approche consiste à effectuer un calcul précis de PARi avec des modèles détaillés utilisant une description complète des paramètres (géométriques et radiatifs du feuillage, et du rayonnement incident [8]. Mais les données nécessaires sont alors nombreuses, complexes à obtenir et donc généralement non disponibles en expérimentation. Pour répondre aux besoins de calcul de l’interception du rayonnement dans les phases d’installation du colza, cet article présente une méthode permettant de calculer epsiloni en tenant compte des principales caractéristiques de la morphologie du couvert et du régime radiatif auquel ce dernier est soumis. Les données nécessaires sont limitées : l’indice foliaire, les taux de couverture du sol (deux définitions, la latitude du lieu considéré, la date et le rayonnement incident quotidien. Ce calcul permet une estimation du coefficient moyen d’extinction k (équation 2. On verra que k peut être corrélé à l’IF, la période de l’année et la latitude du lieu, ce qui permet de proposer une estimation simple de k et donc un calcul simplifié de epsiloni, adapté au cas des faibles IF

  9. Fédération de botanistes, synthèse de contributions citoyennes et transfert de la connaissance naturaliste

    Directory of Open Access Journals (Sweden)

    Delphine Montagne

    2014-06-01

    Full Text Available Tela Botanica est une association dédiée à la botanique. Elle s’appuie sur Internet et les nouvelles technologies pour développer un réseau naturaliste francophone. Cette note rappelle sa construction, ses particularités techniques et organisationnelles. Ces dernières ont permis son succès et le développement de projets pluri-thématiques au service de la connaissance naturaliste.

  10. Investissements directs étrangers au Maroc : impact sur la ...

    African Journals Online (AJOL)

    Mots clés: Investissement direct étranger (IDE), source de l'IDE, capital humain, productivité totale des facteurs, ouverture économique, transfert technologique, croissance économique, Maroc. English Abstract. This article is to study the impact of foreign direct investments (FDI) on total factor productivity (TFP) in Morocco ...

  11. Convective transfers; Transferts convectifs

    Energy Technology Data Exchange (ETDEWEB)

    Accary, G.; Raspo, I.; Bontoux, P. [Aix-Marseille-3 Univ. Paul Cezanne, CNRS, Lab. MSNM-GP UMR 6181, 13 - Marseille (France); Zappoli, B. [Centre National d' Etudes Spatiales (CNES), 31 - Toulouse (France); Polidori, G.; Fohanno, S. [Laboratoire de Thermomecanique, 51 - Reims (France); Hirata, S.C.; Goyeau, B.; Gobin, D. [Paris-6 et Paris-11 Univ., FAST-UMR CNRS 7608, 91 - Orsay (France); Cotta, R.M. [UFRJ/LTTC/PEM/EE/COPPE, Rio de Janeiro (Brazil); Perrin, L.; Reulet, P.; Micheli, F.; Millan, P. [Office National d' Etudes et de Recherches Aerospatiales (ONERA), 31 - Toulouse (France); Menard, V. [France Telecom R and D, 22 - Lannion (France); Benkhelifa, A.; Penot, F. [Ecole Nationale Superieure de Mecanique et d' Aerotechnique (ENSMA), Lab. d' Etudes Thermiques, UMR CNRS 6608, 86 - Poitiers (France); Ng Wing Tin, M.; Haquet, J.F.; Journeau, C. [CEA Cadarache (DEN/DTN/STRI/LMA), Lab. d' Essais pour la Maitrise des Accidents Graves, 13 - Saint-Paul-lez-Durance (France); Naffouti, T.; Hammani, M.; Ben Maad, R. [Faculte des Sciences de Tunis, Lab. d' Energetique et des Transferts Thermique et Massique, Dept. de Physique, Tunis (Tunisia); Zinoubi, J. [Institut Preparatoire aux Etudes d' Ingenieurs de Nabeul (Tunisia); Menard, V.; Le Masson, S.; Nortershauser, D. [France Telecom R and D, 22 - Lannion (France); Stitou, A.; Perrin, L.; Millan, P. [ONERA, 31 - Toulouse (France)

    2005-07-01

    This session about convective transfers gathers 31 articles dealing with: numerical study of the hydrodynamic stability of a bottom heated supercritical fluid layer; establishment of laminar-turbulent transition criteria of free convection dynamic and thermal boundary layers; heat transfer changes in free convection by mechanical and thermal disturbances; natural convection stability in partially porous horizontal layers; experimental characterization of the dynamic and thermal aspects of a natural convection flow inside a confined space; determination of transitions towards non-stationary natural convection inside a differentially heated inclined cavity; interface temperatures for the convection of fluids with variable viscosity; influence of the height of a vertical cylinder on the flow resulting from a plume-thermosyphon interaction; simultaneous measurement of dynamic and thermal fields by thermo-chromic liquid crystals in natural convection; numerical simulation of turbulent natural convection flows inside a heated room; numerical and experimental study of mixed convection heat transfer inside an axisymmetrical network; analysis of laminar flow instabilities in assisted mixed convection; entropy generation in mixed convection; thermal and mass convection in non-stationary regime inside a ventilated cavity; study of a low Reynolds number mixed convection flow; numerical study of a convective flow inside a rotating annular cavity; study of the dynamical behaviour of a transient mixed convection flow inside a thick vertical duct; internal laminar convection: selection criteria for the identification of natural, mixed or forced regimes; turbulent flow and convection heat transfer inside a channel with corrugated walls; study of the impact of an axisymmetrical jet on a concave wall; modeling of volume irreversibilities of turbulent forced convection; numerical study of forced convection irreversibilities around a network of cylindrical tubes; estimation of the exchange coefficient of a mobile cylinder impacted by a water jet - study of single-phase forced convection; second order modeling of the thermal field of an homogenous turbulence; numerical study of the effect of a periodical disturbance on the dynamical structure of the flow downstream of a descending step; numerical study of flows and heat transfers inside the air gap of a rotating machine; dynamical and thermal characteristics of boundary layers inside a turbulent Poiseuille flow with low flow rate ratio downstream of a T-junction; study of convective transfers at the inlet of a cylindrical tube with a low shape ratio (L/D = 8); experimental study of convective transfers in a rotor/stator system subjected to a air flux; correction of the strength and heat flux transferred by a moving cylinder between two parallel planes in Stokes-type regime; algebraic model for the forecasting of turbulent heat fluxes. (J.S.)

  12. Strain Distribution of Au and Ag Nanoparticles Embedded in Al2O3 Thin Film

    Directory of Open Access Journals (Sweden)

    Honghua Huang

    2014-01-01

    Full Text Available Au and Ag nanoparticles embedded in amorphous Al2O3 matrix are fabricated by the pulsed laser deposition (PLD method and rapid thermal annealing (RTA technique, which are confirmed by the experimental high-resolution transmission electron microscope (HRTEM results, respectively. The strain distribution of Au and Ag nanoparticles embedded in the Al2O3 matrix is investigated by the finite-element (FE calculations. The simulation results clearly indicate that both the Au and Ag nanoparticles incur compressive strain by the Al2O3 matrix. However, the compressive strain existing on the Au nanoparticle is much weaker than that on the Ag nanoparticle. This phenomenon can be attributed to the reason that Young’s modulus of Au is larger than that of Ag. This different strain distribution of Au and Ag nanoparticles in the same host matrix may have a significant influence on the technological potential applications of the Au-Ag alloy nanoparticles.

  13. Significant Broadband Photocurrent Enhancement by Au-CZTS Core-Shell Nanostructured Photocathodes

    Science.gov (United States)

    Zhang, Xuemei; Wu, Xu; Centeno, Anthony; Ryan, Mary P.; Alford, Neil M.; Riley, D. Jason; Xie, Fang

    2016-03-01

    Copper zinc tin sulfide (CZTS) is a promising material for harvesting solar energy due to its abundance and non-toxicity. However, its poor performance hinders their wide application. In this paper gold (Au) nanoparticles are successfully incorporated into CZTS to form Au@CZTS core-shell nanostructures. The photocathode of Au@CZTS nanostructures exhibits enhanced optical absorption characteristics and improved incident photon-to-current efficiency (IPCE) performance. It is demonstrated that using this photocathode there is a significant increase of the power conversion efficiency (PCE) of a photoelectrochemical solar cell of 100% compared to using a CZTS without Au core. More importantly, the PCE of Au@CZTS photocathode improved by 15.8% compared to standard platinum (Pt) counter electrode. The increased efficiency is attributed to plasmon resonance energy transfer (PRET) between the Au nanoparticle core and the CZTS shell at wavelengths shorter than the localized surface plasmon resonance (LSPR) peak of the Au and the semiconductor bandgap.

  14. Classification multilabels à partir de signaux EEG d'imaginations motrices combinées : application au contrôle 3D d'un bras robotique

    OpenAIRE

    Lindig León, Cecilia

    2017-01-01

    Brain-Computer Interfaces (BCIs) replace the natural nervous system outputs by artificial ones that do not require the use of peripheral nerves, allowing people with severe motor impairments to interact, only by using their brain activity, with different types of applications, such as spellers, neuroprostheses, wheelchairs, or among others robotics devices. A very popular technique to record signals for BCI implementation purposes consists of electroencephalography (EEG), since in contrast wi...

  15. Contribution au développement et à l'optimisation des machines électriques à courant continu pour des applications Stop-Start

    OpenAIRE

    Demirjian, Razmik

    2013-01-01

    Contribution to the development and optimization of direct-current machines for automotive stop-start applications abstract currently in the automotive market, the demand for hybrid vehicles is booming. These vehicles are meant to reduce fuel consumption and CO2 emissions. Among various possible technological solutions, this thesis deals with one of the Stop-Start technologies of micro-hybrid vehicles that is based on the use of permanent-magnet brushed DC motors. The present work, performed ...

  16. Advanced and Integrated Petrophysical Characterization for CO2 Storage: Application to the Ketzin Site Caractérisation pétrophysique intégrée pour le stockage de CO2 : application au site de Ketzin

    Directory of Open Access Journals (Sweden)

    Fleury M.

    2013-06-01

    Full Text Available Advanced and Integrated Petrophysical Characterization for CO2 Storage: Application to the Ketzin Site — Reservoir simulations and monitoring of CO2 storage require specific petrophysical data. We show a workflow that can be applied to saline aquifers and caprocks in order to provide the minimum data set for realistic estimations of storage potential and perform pertinent simulations of CO2 injection. The presented series of experiments are fully integrated with quantitative log data analysis to estimate porosity, irreducible saturation, drainage capillary pressure and water relative permeability, residual gas saturation, resistivity-saturation relationships and caprock transport properties (permeability and diffusivity. The case considered is a saline aquifer of the Triassic Stuttgart formation studied in the framework of the CO2SINK onshore research storage, the first in situ testing site of CO2 injection in Germany located near the city of Ketzin. We used petrophysical methods that can provide the required data in a reasonable amount of time while still being representative of the in situ injection process. For two phase transport properties, we used the centrifuge technique. For resistivity measurements, we used the Fast Resistivity Index Measurement (FRIM method in drainage and imbibition, at ambient and storage conditions. For caprock characterization, we used a fast NMR (Nuclear Magnetic Resonance deuterium tracer technique to measure diffusivity and a modified steady state innovative technique to determine permeability. Entry pressure has also been evaluated using several methods. Resistivity and NMR logs were analyzed to provide a continuous estimation of irreducible saturation for the entire storage zone and to judge on the representativity of the samples analyzed in the laboratory. For the Ketzin site, the storage zone is a clayey sandstone of fluvial origin locally highly cemented, with porosity around 30% and permeability ranging

  17. Properties of transparent and conductive Al:ZnO/Au/Al:ZnO multilayers on flexible PET substrates

    International Nuclear Information System (INIS)

    Dimopoulos, T.; Bauch, M.; Wibowo, R.A.; Bansal, N.; Hamid, R.; Auer, M.; Jäger, M.; List-Kratochvil, E.J.W.

    2015-01-01

    Highlights: • Transparent, low resistive AZO/Au/AZO layers were sputtered on PET substrates. • AZO/Au/AZO has higher figure of merit than ITO for specific Au thicknesses. • The resistance of AZO/Au/AZO is stable against repetitive substrate bending. • AZO/Au/AZO electrode performance is comparable to ITO in light emitting diodes. - Abstract: We investigate the structural, electrical and optical properties of transparent electrodes, consisting of Al-doped ZnO (AZO) and ultrathin Au layers, sputtered on polyethylene terephthalate (PET). These electrodes are relevant for optoelectronic devices and thin film photovoltaics. When deposited on AZO, Au films as thin as 3 nm form electrically conductive, meandering structures, whereas uniform Au films are obtained from a thickness of 5 nm. The sheet resistance decreases with Au thickness, reaching 7 Ω for 11 nm-thick Au. AZO/Au/AZO trilayers combine lowest resistance with highest transparency, while their resistance stability against bending fatigue is superior to the Sn-doped In 2 O 3 (ITO) electrode. The figure of merit of AZO/Au/AZO is larger than of ITO for Au thickness equal to or larger than 9 nm. To demonstrate the applicability of the AZO/Au/AZO transparent electrode, simple organic light emitting diodes were fabricated and tested in comparison to PET/ITO standard substrates

  18. Production and novel radiochemical separation of 194Au from Pt for use in multi-modality nanoparticles

    OpenAIRE

    Graves, S.; Goel, S.; Chen, F.; Valdovinos, H.; Barnhart, T.; Cai, W.; Nickles, R.

    2015-01-01

    Introduction Gold nanoparticles (AuNPs) have demonstrated their incredible versatility in applications such as in vitro and in vivo imaging, cancer therapy, and drug delivery.[1-3] These AuNPs come in many shapes including nanospheres, nanorods, nanoshells, and nanocages. Their versatility stems from the ability to construct or label a single AuNP with many functions. Many types of AuNPs are inherently flourescent, allowing for ex vivo utilization as well as small animal fluorescence imagi...

  19. Fabrication of Au-Pd Core-shell Nanoparticles using Au Thin-Film Dewetting at High Temperature and Chemical Synthesis Methods

    Energy Technology Data Exchange (ETDEWEB)

    Kim, Min-Gyu; Lee, Hye-Jung; Oh, Yong-Jun [Hanbat National Univ., Daejeon (Korea, Republic of)

    2016-07-15

    Au-Pd bimetallic nanoparticles (NPs) have received a lot of attention in the fields of catalysts and hydrogen sensors. In this study, Au-Pd core-shell NP arrays were successfully fabricated using two steps: formation of the ordered array of Au NPs cores via solid-state dewetting of a Au thin film on a topographic silica substrate, and Pd shell formation via chemical synthesis using two different surfactants (CTAB and CTAC). Using the CTAB surfactant in particular, a 2-D composite structure comprised of an ordered array of Au-Pd NPs, with smaller Pd NPs on the nanoscopic gaps between the Au-Pd NPs, could be formed. This structure is expected to have potential application in resistance-base hydrogen sensors.

  20. Transverse expansion in 197 Au + 197 Au collisions at RHIC

    International Nuclear Information System (INIS)

    Cheng, Y.; Liu, F.; Liu, K.; Schweda, K.; Xu, N.

    2003-01-01

    Using the RQMD model, transverse momentum distributions and particle ratios are studied for 197 Au + 197 Au collisions at √s NN = 200 GeV. In particular, they present results on the mean transverse momentum of charged pions, charged kaons, protons and anti-protons and compare with experimental measurements. They discuss an approach to study early partonic collectivity in high energy nuclear collisions

  1. Centrality dependence of antiproton production in Au+Au collisions

    Energy Technology Data Exchange (ETDEWEB)

    Beavis, D.; Bennett, M.J.; Carroll, J.B.; Chiba, J.; Chikanian, A.; Crawford, H.; Cronqvist, M.; Dardenne, Y.; Debbe, R.; Doke, T.; Engelage, J.; Greiner, L.; Hallman, T.J.; Hayano, R.S.; Heckman, H.H.; Kashiwagi, T.; Kikuchi, J.; Kumar, S.; Kuo, C.; Lindstrom, P.J.; Mitchell, J.W.; Nagamiya, S.; Nagle, J.L.; Pope, J.K.; Stankus, P.; Tanaka, K.H.; Welsh, R.C.; Zhan, W. [Brookhaven National Laboratory, Upton, New York (United States)]|[A.W. Wright Nuclear Structure Laboratory, Yale University, New Haven, Connecticut (United States)]|[University of California at Los Angeles, Los Angeles California (United States)]|[National Laboratory for High Energy Physics (KEK), Tsukuba (Japan)]|[University of California Space Sciences Laboratory, Berkeley California (United States)]|[Waseda University, Tokyo (Japan)]|[University of Tokyo, Tokyo (Japan)]|[Lawrence Berkeley Laboratory, Berkeley California (United States)]|[Universities Space Sciences Research Association/Goddard Space Flight Center, Greenbelt, Maryland (United States)]|[Nevis Laboratory, Columbia University, Irvington, New York (United States)]|[Johns Hopkins University, Baltimore, Maryland (United States); (E878 Collaboration)

    1995-11-13

    We have measured the yields of antiprotons in Au+Au interactions in the rapidity range 1.2{lt}{ital y}{lt}2.8 as a function of centrality using a beam line spectrometer. The shapes of the invariant multiplicity distributions at {ital p}{sub {ital t}}=0 are used to explore the dynamics of antiproton production and annihilation. {copyright} {ital 1995} {ital The} {ital American} {ital Physical} {ital Society}.

  2. Face au risque

    CERN Document Server

    Grosse, Christian; November, Valérie

    2007-01-01

    Ce volume collectif sur le risque inaugure la collection L'ÉQUINOXE. Ancré dans l'histoire pour mesurer les continuités et les ruptures, il illustre la manière dont les sciences humaines évaluent et mesurent les enjeux collectifs du risque sur les plans politiques, scientifiques, énergétiques, juridiques et éthiques. Puisse-t-il nourrir la réflexion sur la culture et la prévention du risque. Ses formes épidémiques, écologiques, sociales, terroristes et militaires nourrissent les peurs actuelles, structurent les projets sécuritaires et constituent - sans doute - les défis majeurs à notre modernité. Dans la foulée de la richesse scientifique d'Equinoxe, L'ÉQUINOXE hérite de son esprit en prenant à son tour le pari de contribuer - non sans risque - à enrichir en Suisse romande et ailleurs le champ éditorial des sciences humaines dont notre société a besoin pour forger ses repères. Après Face au risque suivra cet automne Du sens des Lumières. (MICHEL PORRET Professeur Ordinaire à la F...

  3. The distribution, atmospheric transfer, and assessment of krypton-85; Distribution, transfert atmospherique et bilan du krypton-85

    Energy Technology Data Exchange (ETDEWEB)

    Pannetier, R. [Commissariat a l' Energie Atomique, 92 - Fontenay-aux-Roses (France). Centre d' Etudes Nucleaires

    1968-06-01

    Techniques for sampling and measuring krypton-85 have been developed which allowed to determine its geographical distribution. From its use as a tracer, an evaluation of the air masses which cross over the subtropical fronts has been derived. Besides, the stratospheric character of air pollution by krypton-85 at the level of the antarctic soil has been shown out. Levels of krypton-85 seem to point out to an underestimation of the assessment of nuclear explosion fission energies as adopted by the United Nations Scientific committee on the effects of atomic radiation and emphasize the need to set limits as soon as possible to the amounts of krypton-85 released to the atmosphere by fuel-reprocessing plants. (author) [French] La mise au point de techniques de prelevement et de mesure du krypton-85 atmospherique a permis de determiner sa repartition geographique. De son utilisation comme traceur on deduit une evaluation des masses d'air qui traversent les fronts subtropicaux. Par ailleurs, le caractere stratospherique de la pollution de l'air par le krypton-85 au niveau du sol antarctique est mis en evidence. Le bilan du krypton-85 semble reveler une sous-estimation du bilan des energies de fission des explosions adopte par le Comite scientifique des Nations Unies et souligne la necessite de limiter des que possible les quantites de krypton-85 rejetees dans l'atmosphere par les usines de traitement de combustibles irradies. (auteur)

  4. Extraction of Source Images in Au+Au and d+Au collisions at RHIC

    International Nuclear Information System (INIS)

    Chung, P.; Taranenko, A.; Lacey, R.; Holzmann, W.; Alexander, J.; Issah, M.

    2005-01-01

    The PHENIX Collaboration has performed a systematic study of two-pion correlations in Au+Au and d+Au collisions at RHIC (s=200AGeV). The correlations have been analyzed using the Imaging technique of Brown and Danielewicz to extract the two-pion source functions as a function of mT and centrality. The source images are characterised by a short-range Gaussian-like core and a long-range exponential-like tail with a characteristic radius about 3 times that of the Gaussian core. The mT and centrality dependence of the source parameters indicate that the two structures are intricately related

  5. La micro-entreprise moyen de lutte contre la pauvreté: mise en évidence par application au niveau des régions tunisiennes = Micro-enterprises are the medium against poverty: Its application in Tunisian regions

    Directory of Open Access Journals (Sweden)

    Makram Gaaliche

    2013-12-01

    Full Text Available La contribution du secteur des micro-entreprises en Tunisie, dans la lutte contre la pauvreté, s’est manifestée de telle sorte que, tout accroissement du nombre d’unité de micro-entreprise entraîne une réduction du taux de pauvreté. En outre, il s’est avérée que la participation de ces petites unités dans la lutte contre la pauvreté, varie d’une région à une autre, selon le secteur d’activité y exerçantes. La détection d’une telle spécialisation sectorielle au niveau de la lutte contre la pauvreté, permet l’adoption de politiques régionales ciblées, destinées à encourager la création de micro-entreprises, au niveau des secteurs d’activité les plus pertinents.In Tunisia, the contribution of the microentreprises sector, in the fight against poverty, has appeared so that, every increasing in the number of the microentreprises involves a reduction of the poverty rate. In addition, it proved that the participation of these small unities in the fight against poverty varies from one area to another, according to the activity sectors. The detection of such sectoral specialization on the level of the fight against poverty, allows the adoption of targeted regional policies, intended to encourage the creation of microentreprises, in the most relevant activity sectors.

  6. La micro-entreprise moyen de lutte contre la pauvreté: mise en évidence par application au niveau des régions tunisiennes = Micro-enterprises are the medium against poverty: Its application in Tunisian regions

    Directory of Open Access Journals (Sweden)

    Makram Gaaliche

    2014-07-01

    Full Text Available Résumé La contribution du secteur des micro-entreprises en Tunisie, dans la lutte contre la pauvreté, s’est manifestée de telle sorte que, tout accroissement du nombre d’unité de micro-entreprise entraîne une réduction du taux de pauvreté. En outre, il s’est avérée que la participation de ces petites unités dans la lutte contre la pauvreté, varie d’une région à une autre, selon le secteur d’activité y exerçantes. La détection d’une telle spécialisation sectorielle au niveau de la lutte contre la pauvreté, permet l’adoption de politiques régionales ciblées, destinées à encourager la création de micro-entreprises, au niveau des secteurs d’activité les plus pertinents. Abstract In Tunisia, the contribution of the microentreprises sector, in the fight against poverty, has appeared so that, every increasing in the number of the microentreprises involves a reduction of the poverty rate. In addition, it proved that the participation of these small unities in the fight against poverty varies from one area to another, according to the activity sectors. The detection of such sectoral specialization on the level of the fight against poverty, allows the adoption of targeted regional policies, intended to encourage the creation of microentreprises, in the most relevant activity sectors.

  7. Le CRDI au Sri Lanka

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

    Le CRDI appuie la recherche au Sri. Lanka depuis 1973. Il s'est d'abord concentré sur l'amélioration des pratiques agricoles. Par exemple, grâce à la mise au point d'un système de rizi - culture permettant d'exploiter les pluies de mousson, les riziculteurs ont triplé leurs rendements en quatre ans. Ils ont été nombreux à ...

  8. Comparative study of anchoring groups for molecular electronics: structure and conductance of Au-S-Au and Au-NH2-Au junctions

    DEFF Research Database (Denmark)

    Kristensen, Iben Sig; Mowbray, Duncan; Thygesen, Kristian Sommer

    2008-01-01

    of identifying and comparing the intrinsic properties of two commonly used anchoring groups, namely thiol and amine groups, we have calculated the atomic structure and conductance traces of different Au-S-Au and Au-NH2-Au nanojunctions using density functional theory (DFT). Whereas NH2 shows a strong structural...

  9. Bonding properties of FCC-like Au 44 (SR) 28 clusters from X-ray absorption spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Yang, Rui [Department of Chemistry, Dalhousie University, Halifax, NS B3H 4R2, Canada.; Chevrier, Daniel M. [Department of Chemistry, Dalhousie University, Halifax, NS B3H 4R2, Canada.; Zeng, Chenjie [Department of Chemistry, Carnegie Mellon University, Pittsburgh, PA 15213, USA.; Jin, Rongchao [Department of Chemistry, Carnegie Mellon University, Pittsburgh, PA 15213, USA.; Zhang, Peng [Department of Chemistry, Dalhousie University, Halifax, NS B3H 4R2, Canada.

    2017-11-01

    Thiolate-protected gold clusters with precisely controlled atomic composition have recently emerged as promising candidates for a variety of applications because of their unique optical, electronic, and catalytic properties. The recent discovery of the Au44(SR)28 total structure is considered as an interesting finding in terms of the face-centered cubic (FCC)-like core structure in small gold-thiolate clusters. Herein, the unique bonding properties of Au44(SR)28 is analyzed using temperature-dependent X-ray absorption spectroscopy (XAS) measurements at the Au L3-edge and compared with other FCC-like clusters such as Au36(SR)24 and Au28(SR)20. A negative thermal expansion was detected for the Au–Au bonds of the metal core (the first Au–Au shell) and was interpreted based on the unique Au core structure consisting of the Au4 units. EXAFS fitting results from Au28(SR)20, Au36(SR)24, and Au44(SR)28 show a size-dependent negative thermal expansion behavior in the first Au–Au shell, further highlighting the importance of the Au4 units in determining the Au core bonding properties and shedding light on the growth mechanism of these FCC-like Au clusters.

  10. Controlled electrodeposition of Au monolayer film on ionic liquid

    Science.gov (United States)

    Ma, Qiang; Pang, Liuqing; Li, Man; Zhang, Yunxia; Ren, Xianpei; Liu, Shengzhong Frank

    2016-05-01

    Gold (Au) nanoparticles have been attractive for centuries for their vibrant appearance enhanced by their interaction with sunlight. Nowadays, there have been tremendous research efforts to develop them for high-tech applications including therapeutic agents, sensors, organic photovoltaics, medical applications, electronics and catalysis. However, there remains to be a challenge to fabricate a monolayer Au coating with complete coverage in controlled fashion. Here we present a facile method to deposit a uniform Au monolayer (ML) film on the [BMIM][PF6] ionic liquid substrate using an electrochemical deposition process. It demonstrates that it is feasible to prepare a solid phase coating on the liquid-based substrate. Moreover, the thickness of the monolayer coating can be controlled to a layer-by-layer accuracy.

  11. History Matching of Production and 4D Seismic Data: Application to the Girassol Field, Offshore Angola Calage simultané des données de production et de sismique 4D : application au champ de Girassol, Offshore Angola

    Directory of Open Access Journals (Sweden)

    Roggero F.

    2012-04-01

    quantitative des données de sismique 4D en modélisation de réservoir. Cette publication propose une méthodologie innovante basée sur des méthodes avancées de calage simultané des modèles 3D de réservoir par les données de production et de sismique 4D. Cette approche intègre dans le même processus de calage d’historique la modélisation géostatistique, les changements d’échelle, la simulation des écoulements et la modélisation pétro-élastique. Les données simulées de production et de sismique 4D sont comparées aux données réelles par l’intermédiaire d’une fonction objectif, qu’un algorithme d’optimisation par ajustement de surface de réponse permet de minimiser. La méthode de déformation graduelle est utilisée pour contraindre globalement ou localement la réalisation en facies du modèle géologique à l’échelle fine. De plus, une nouvelle technique est mise en oeuvre pour mettre à jour les proportions de facies pendant le processus d’optimisation en intégrant les informations de sismique 4D. Une application réalisée avec succès sur le champ de Girassol est présentée. Girassol est un vaste réservoir turbiditique, complexe et faillé, situé dans les grands fonds au large de l’Angola. Un modèle géostatistique détaillé a d’abord été construit pour décrire les hétérogénéités du réservoir à l’échelle géologique fine, en se basant sur les données initiales de sismique 3D. Le modèle a ensuite été contraint par les données de production et de sismique 4D après inversion, en explorant les réalisations géostatistiques par déformation graduelle et en ajustant les proportions de facies. L’intégration des données de sismique 4D a conduit à de meilleures prévisions de production, confirmées par une nouvelle campagne sismique acquise deux ans après la période d’historique initialement considérée. Les données de sismique 4D ont aussi contribué à mieux caractériser la distribution spatiale

  12. Spherical and polygonal shape of Au nanoparticles coated functionalized polymer microspheres

    Energy Technology Data Exchange (ETDEWEB)

    Xu, Ting; Li, Yingzhi; Zhang, Junxian; Qi, Yalong; Zhao, Xin; Zhang, Qinghua, E-mail: qhzhang@dhu.edu.cn

    2015-08-01

    Highlights: • PS/PPy with well-defined core/shell structures was prepared in aqueous solution. • Au NPs were coated on PS/PPy by the fixation and continuous growth process. • Mercapto-groups played a role in the number and morphology of Au shell. • PS/PPy/Au had homogeneous and dense Au coatings with different shape. - Abstract: Uniform polystyrene (PS)/polypyrrole (PPy) composite microspheres with well-defined core/shell structures are synthesized by chemical oxidative polymerization. Gold nanoparticles (Au NPs) are successfully coated on the surface of PS/PPy microspheres by means of electrostatic interactions due to the functionalized PPy coatings supplying sufficient amino groups and the additive of mercapto acetic acid. Furthermore, the as-prepared PS/PPy/Au microspheres serving as seeds facilitate Au NPs further growth by in situ reduction in HAuCl{sub 4} solution to obtain PS/PPy/Au spheres with the core/shell/shell structure. Morphology observation demonstrates that the monodisperse PS/PPy/Au microspheres compose of uniform cores and the compact coatings containing distinct two layers. X-ray diffraction and X-ray photoelectron spectroscope confirm the existence of PPy and Au on the surface of the composite spheres. This facile approach to preparing metal-coated polymer spheres supplies the potential applications in biosensors, electronics and medical diagnosis.

  13. Core-shell Au/Ag nanoparticles embedded in silicate sol-gel ...

    Indian Academy of Sciences (India)

    Core-shell Au/Ag nanoparticles embedded in silicate sol-gel network for sensor application towards hydrogen peroxide ... The present study highlights the influence of molar composition of Ag nanoparticles in the Au/Ag bimetallic composition towards the electrocatalytic reduction and sensing of hydrogen peroxide in ...

  14. Influence of Ti and Cr Adhesion Layers on Ultrathin Au Films

    DEFF Research Database (Denmark)

    Todeschini, Matteo; Bastos da Silva Fanta, Alice; Jensen, Flemming

    2017-01-01

    Efficient adhesion of gold thin films on dielectric or semiconductor substrates is essential in applications and research within plasmonics, metamaterials, 2D materials, and nanoelectronics. As a consequence of the relentless downscaling in nanoscience and technology, the thicknesses of adhesion...... layer and overlayer have reached tens of nanometers, and it is unclear if our current understanding is sufficient. In this report, we investigated how Cr and Ti adhesion layers influence the nanostructure of 2-20 nm thin Au films by means of high-resolution electron microscopy, complemented with atomic...... force microscopy and X-ray photoelectron spectroscopy. Pure Au films were compared to Ti/Au and Cr/Au bilayer systems. Both Ti and Cr had a striking impact on grain size and crystal orientation of the Au overlayer, which we interpret as the adhesion layer-enhanced wetting of Au and the formation...

  15. Photoluminescence enhancement in few-layer WS2 films via Au nanoparticles

    Directory of Open Access Journals (Sweden)

    Sin Yuk Choi

    2015-06-01

    Full Text Available Nano-composites of two-dimensional atomic layered WS2 and Au nanoparticles (AuNPs have been fabricated by sulfurization of sputtered W films followed by immersing into HAuCl4 aqueous solution. The morphology, structure and AuNPs distribution have been characterized by electron microscopy. The decorated AuNPs can be more densely formed on the edge and defective sites of triangle WS2. We have compared the optical absorption and photoluminescence of bare WS2 and Au-decorated WS2 layers. Enhancement in the photoluminescence is observed in the Au-WS2 nano-composites, attributed to localized surface plasmonic effect. This work provides the possibility to develop photonic application in two-dimensional materials.

  16. L’apprentissage au cern

    CERN Multimedia

    2007-01-01

    pour les professions d’électronicien(ne) et de laborantin(e) en physique L’apprentissage au CERN est régi par les lois, règlements et contrats en vigueur dans le canton de Genève. En cas de réussite à l’examen de fin d’apprentissage, les apprentis obtiennent le Certificat fédéral de capacité suisse (CFC). 6 places au total sont ouvertes au recrutement pour les deux professions. L’apprentissage dure 4 ans. Minima requis pour faire acte de candidature : avoir au moins 15 ans et moins de 21 ans à la date de début de l’apprentissage ; avoir terminé la scolarité obligatoire, au minimum 9e du Cycle d’orientation genevois (3e en France) ; être ressortissant d’un pays membre du CERN (Allemagne, Autriche, Belgique, Bulgarie, Danemark, Espagne, Finlande, France, Grèce, Hongrie, Italie, Norvège, Pays-Bas, Pologne, Portugal, Royaume-Uni, République tchèque, République slovaque , Suède, Suisse) ; pour les résidents en Suisse : être ressortissant su...

  17. Studies of Au/SAMs/PEDOT-PSS/Au tunnel junctions

    Science.gov (United States)

    Sun, Nan; Lieberman, Marya; Ruggiero, Steven

    2008-03-01

    We report on tunneling through thin organic films. Junctions of the form: Au/SAMs/Polymer/Au were prepared on electronic-grade Si substrates with Self-Assembled Monolayers (SAMs) including octanedithiol (HS-C8H16-SH) and mercaptohexadecanoic (HS-C15H30-COOH). A transitional conducting polymer film PEDOT-PSS was spun on to the SAMs layer, and junctions were completed with a gold film. X-ray photoelectron spectroscopy (XPS) was employed to monitor the quality of the SAMs films. The electron tunneling properties including dI/dV and d^2I/dV^2 versus bias for the SAMs are discussed.

  18. Biosynthesis of Au, Ag and Au-Ag nanoparticles using edible mushroom extract

    Science.gov (United States)

    Philip, Daizy

    2009-07-01

    Integration of green chemistry principles to nanotechnology is one of the key issues in nanoscience research. There is growing need to develop environmentally benign metal nanoparticle synthesis process that do not use toxic chemicals in the synthesis protocols to avoid adverse effects in medical applications. Here, it is a report on extracellular synthesis method for the preparation of Au, Ag and Au-Ag nanoparticles in water, using the extract of Volvariella volvacea, a naturally occurring edible mushroom, as reducing and protecting agents. Gold nanoparticles of different sizes (20-150 nm) and shapes from triangular nanoprisms to nearly spherical and hexagonal are obtained by this novel method. The size and shape of gold nanoparticles are also found to depend on temperature of the extract. The silver nanoparticles are spherical with size ˜15 nm. There is increased productivity of nanoparticles as shown by sharp and intense surface plasmon resonance bands for the nanoparticles prepared using an excess of the extract. The Au-Ag nanoparticles prepared by co-reduction has only one plasmon band due to alloying of the constituents. All the synthesized nanoparticles are found to be photoluminescent and are highly crystalline as shown by SAED and XRD patterns with fcc phase oriented along the (1 1 1) plane. FTIR measurements were carried out to identify the possible biomolecules responsible for capping and efficient stabilization of the nanoparticles. It is found that Au nanoparticles are bound to proteins through free amino groups and silver nanoparticles through the carboxylate group of the amino acid residues. The position and intensity of the emission band is found to depend on composition of the nanoparticles indicating the possible use in therapeutic applications.

  19. Resonance energy transfer between fluorescent BSA protected Au nanoclusters and organic fluorophores.

    Science.gov (United States)

    Raut, Sangram; Rich, Ryan; Fudala, Rafal; Butler, Susan; Kokate, Rutika; Gryczynski, Zygmunt; Luchowski, Rafal; Gryczynski, Ignacy

    2014-01-07

    Bovine serum albumin (BSA) protected nanoclusters (Au and Ag) represent a group of nanomaterials that holds great promise in biophysical applications due to their unique fluorescence properties and lack of toxicity. These metal nanoclusters have utility in a variety of disciplines including catalysis, biosensing, photonics, imaging and molecular electronics. However, they suffer from several disadvantages such as low fluorescence quantum efficiency (typically near 6%) and broad emission spectrum (540 nm to 800 nm). We describe an approach to enhance the apparent brightness of BSA Au clusters by linking them with a high extinction donor organic dye pacific blue (PB). In this conjugate PB acts as a donor to BSA Au clusters and enhances its brightness by resonance energy transfer (RET). We found that the emission of BSA Au clusters can be enhanced by a magnitude of two-fold by resonance energy transfer (RET) from the high extinction donor PB, and BSA Au clusters can act as an acceptor to nanosecond lifetime organic dyes. By pumping the BSA Au clusters using a high extinction donor, one can increase the effective brightness of less bright fluorophores like BSA Au clusters. Moreover, we prepared another conjugate of BSA Au clusters with the near infrared (NIR) dye Dylight 750 (Dy750), where BSA Au clusters act as a donor to Dy750. We observed that BSA Au clusters can function as a donor, showing 46% transfer efficiency to the NIR dye Dy750 with a long lifetime component in the acceptor decay through RET. Such RET-based probes can be used to prevent the problems of a broad emission spectrum associated with the BSA Au clusters. Moreover, transferring energy from BSA Au clusters to Dy750 will result in a RET probe with a narrow emission spectrum and long lifetime component which can be utilized in imaging applications.

  20. Nitrogen mineralization from 'AU Golden' sunn hemp residue

    Science.gov (United States)

    The tropical legume sunn hemp (Crotalaria juncea) cultivar ‘AU Golden’ has the potential to provide substantial amounts of nitrogen (N) to subsequent crops that could reduce recommended application rates of synthetic N fertilizers. Nitrogen fertilization problems via legumes are often due to asynch...

  1. Chiral magnetic effect search in p+Au, d+Au and Au+Au collisions at RHIC

    Science.gov (United States)

    Zhao, Jie

    2018-01-01

    Metastable domains of fluctuating topological charges can change the chirality of quarks and induce local parity violation in quantum chromodynamics. This can lead to observable charge separation along the direction of the strong magnetic field produced by spectator protons in relativistic heavy-ion collisions, a phenomenon called the chiral magnetic effect (CME). A major background source for CME measurements using the charge-dependent azimuthal correlator (Δϒ) is the intrinsic particle correlations (such as resonance decays) coupled with the azimuthal elliptical anisotropy (v2). In heavy-ion collisions, the magnetic field direction and event plane angle are correlated, thus the CME and the v2-induced background are entangled. In this report, we present two studies from STAR to shed further lights on the background issue. (1) The Δϒ should be all background in small system p+Au and d+Au collisions, because the event plane angles are dominated by geometry fluctuations uncorrelated to the magnetic field direction. However, significant Δϒ is observed, comparable to the peripheral Au+Au data, suggesting a background dominance in the latter, and likely also in the mid-central Au+Au collisions where the multiplicity and v2 scaled correlator is similar. (2) A new approach is devised to study Δϒ as a function of the particle pair invariant mass (minv) to identify the resonance backgrounds and hence to extract the possible CME signal. Signal is consistent with zero within uncertainties at high minv. Signal at low minv, extracted from a two-component model assuming smooth mass dependence, is consistent with zero within uncertainties.

  2. Application of Alkaline Waterflooding to a High Acidity Crude Oil Application de l'injection d'eau alcaline au cas d'un pétrole brut à forte acidité

    Directory of Open Access Journals (Sweden)

    Abdel-Waly A.

    2006-11-01

    Full Text Available The main objective of this work was to study the enhanced recovery of a high acidity crude oil (South Geisum crude by alkaline solutions. Different properties of South Geisum crude oil, namely acidity, interfacial tension, and contact angle, were investigated. Displacement tests were carried out to study the effect of alkaline slug concentration, slug size, oil alkali type, and temperature viscosity on recovery. South Geisum crude oil is a highly acidic crude (4. 38 mg KOH/g. It was found that the interfacial tension between crude oil and formation water decreases with increasing alkaline concentration until it reaches a minimum, after which it increases again with a further increase in alkaline concentration. Interfacial tension between crude oil and displacement water also decreases with increasing alkaline concentration. Contact angle measurements indicated oil-wetting conditions that increase by the addition of alkaline solutions. Displacement floods showed that, at the early stages of displacement, oil recovery increases with increasing alkaline concentration until it reaches a maximum at 4 % by weight NaOH concentration. Also, at such early stages, an excessive increase in alkaline concentration results in lower oil recovery. On the other hand, after the injection of many pore volumes of water, oil recovery is almost the same regardless of the alkaline concentration. It was found also that oil recovery increases with increasing alkaline slug size until it reaches a maximum at 15 % PV, after which increasing slug size results in decreasing oil recovery (this result has not as yet been reported in the literature. Sodium hydroxide slugs produce more oil recovery than sodium carbonate slugs. Oil recovery increases with increasing temperature (from 25 to 55°C and decreasing oil viscosity. Cet article traite de la récupération, au moyen de solutions alcalines, d'un pétrole brut à forte acidité (brut de Geisum-Sud. Différentes propri

  3. Hadron production in Au-Au collisions at RHIC

    International Nuclear Information System (INIS)

    Braun-Munzinger, P.; Magestro, D.; Redlich, K.; Wroclaw Univ.; Stachel, J.

    2001-05-01

    We present an analysis of particle production yields measured in central Au-Au collisions at RHIC in the framework of the statistical thermal model. We demonstrate that the model extrapolated from previous analyses at SPS and AGS energy is in good agreement with the available experimental data at √(s) = 130 GeV implying a high degree of chemical equilibration. Performing a χ 2 fit to the data, the range of thermal parameters at chemical freezeout is determined. At present, the best agreement of the model and the data is obtained with the baryon chemical potential μ B ≅ 51 ± 6 MeV and temperature T ≅ 175 ± 7 MeV. More ratios, such as multistrange baryon to meson, would be required to further constrain the chemical freezeout conditions. Extrapolating thermal parameters to higher energy, the predictions of the model for particle production in Au-Au reactions at √(s) = 200 GeV are also given. (orig.)

  4. Level lifetimes of Au52+ in Au plasma

    International Nuclear Information System (INIS)

    Liu Bo; Zhu Zhiyan; Jiang Gang; Zhu Zhenghe

    2003-01-01

    Based on the extended relativistic multiconfiguration Dirac-Fock theory, the level lifetimes, level widths and wavelengths of Au 52+ have been calculated using the General-purpose Relativistic Atomic Structure Program. The wavelengths obtained are in good agreement with the experimental data available. The relationship between the level lifetimes and the level widths satisfies the Heisenberg uncertainty principle

  5. Reduced sintering of mass-selected Au clusters on SiO2 by alloying with Ti: an aberration-corrected STEM and computational study

    DEFF Research Database (Denmark)

    Niu, Yubiao; Schlexer, Philomena; Sebök, Béla

    2018-01-01

    Au nanoparticles represent the most remarkable example of a size effect in heterogeneous catalysis. However, a major issue hindering the use of Au nanoparticles in technological applications is their rapid sintering. We explore the potential of stabilizing Au nanoclusters on SiO2 by alloying them...... in the Au/Ti clusters, but in line with the model computational investigation, Au atoms were still present on the surface. Thus size-selected, deposited nanoalloy Au/Ti clusters appear to be promising candidates for sustainable gold-based nanocatalysis....

  6. Dynamic relaxation processes in compressible multiphase flows. Application to evaporation phenomena

    Directory of Open Access Journals (Sweden)

    Le Métayer O.

    2013-07-01

    Full Text Available Phase changes and heat exchanges are examples of physical processes appearing in many industrial applications involving multiphase compressible flows. Their knowledge is of fundamental importance to reproduce correctly the resulting effects in simulation tools. A fine description of the flow topology is thus required to obtain the interfacial area between phases. This one is responsible for the dynamics and the kinetics of heat and mass transfer when evaporation or condensation occurs. Unfortunately this exchange area cannot be obtained easily and accurately especially when complex mixtures (drops, bubbles, pockets of very different sizes appear inside the transient medium. The natural way to solve this specific trouble consists in using a thin grid to capture interfaces at all spatial scales. But this possibility needs huge computing resources and can be hardly used when considering physical systems of large dimensions. A realistic method is to consider instantaneous exchanges between phases by the way of additional source terms in a full non-equilibrium multiphase flow model [2,15,17]. In this one each phase obeys its own equation of state and has its own set of equations and variables (pressure, temperature, velocity, energy, entropy,.... When enabling the relaxation source terms the multiphase mixture instantaneously tends towards a mechanical or thermodynamic equilibrium state at each point of the flow. This strategy allows to mark the boundaries of the real flow behavior and to magnify the dominant physical effects (heat exchanges, evaporation, drag,... inside the medium. A description of the various relaxation processes is given in the paper. Les changements de phase et les transferts de chaleur sont des exemples de phénomènes physiques présents dans de nombreuses applications industrielles faisant intervenir des écoulements compressibles multiphasiques. La connaissance des mécanismes associés est primordiale afin de reproduire

  7. Antimicrobial photodynamic activity and cytocompatibility of Au25(Capt)18clusters photoexcited by blue LED light irradiation.

    Science.gov (United States)

    Miyata, Saori; Miyaji, Hirofumi; Kawasaki, Hideya; Yamamoto, Masaki; Nishida, Erika; Takita, Hiroko; Akasaka, Tsukasa; Ushijima, Natsumi; Iwanaga, Toshihiko; Sugaya, Tsutomu

    2017-01-01

    Antimicrobial photodynamic therapy (aPDT) has beneficial effects in dental treatment. We applied captopril-protected gold (Au 25 (Capt) 18 ) clusters as a novel photosensitizer for aPDT. Photoexcited Au clusters under light irradiation generated singlet oxygen ( 1 O 2 ). Accordingly, the antimicrobial and cytotoxic effects of Au 25 (Capt) 18 clusters under dental blue light-emitting diode (LED) irradiation were evaluated. 1 O 2 generation of Au 25 (Capt) 18 clusters under blue LED irradiation (420-460 nm) was detected by a methotrexate (MTX) probe. The antimicrobial effects of photoexcited Au clusters (0, 5, 50, and 500 μg/mL) on oral bacterial cells, such as Streptococcus mutans, Aggregatibacter actinomycetemcomitans , and Porphyromonas gingivalis , were assessed by morphological observations and bacterial growth experiments. Cytotoxicity testing of Au clusters and blue LED irradiation was then performed against NIH3T3 and MC3T3-E1 cells. In addition, the biological performance of Au clusters (500 μg/mL) was compared to an organic dye photosensitizer, methylene blue (MB; 10 and 100 μg/mL). We confirmed the 1 O 2 generation ability of Au 25 (Capt) 18 clusters through the fluorescence spectra of oxidized MTX. Successful application of photoexcited Au clusters to aPDT was demonstrated by dose-dependent decreases in the turbidity of oral bacterial cells. Morphological observation revealed that application of Au clusters stimulated destruction of bacterial cell walls and inhibited biofilm formation. Aggregation of Au clusters around bacterial cells was fluorescently observed. However, photoexcited Au clusters did not negatively affect the adhesion, spreading, and proliferation of mammalian cells, particularly at lower doses. In addition, application of Au clusters demonstrated significantly better cytocompatibility compared to MB. We found that a combination of Au 25 (Capt) 18 clusters and blue LED irradiation exhibited good antimicrobial effects through 1 O 2

  8. Le CRDI au Bhoutan

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

    tance. Le collège a adopté une application. Web qui permet aux enseignants de créer des sites d'apprentissage en ligne, il a offert des cours en informatique aux enseignants et aux étudiants et il a conçu son propre site Web. Il a également établi neuf centres d'études régionaux dans des écoles. La mesure des progrès.

  9. A facile and green strategy for the synthesis of Au, Ag and Au-Ag alloy nanoparticles using aerial parts of R. hypocrateriformis extract and their biological evaluation.

    Science.gov (United States)

    Godipurge, S S; Yallappa, S; Biradar, Naveen J; Biradar, J S; Dhananjaya, B L; Hegde, Gajanan; Jagadish, K; Hegde, Gurumurthy

    2016-12-01

    A facile and green strategy is reported here to synthesize gold (Au), silver (Ag) and gold-silver (Au-Ag) alloy nanoparticles (NPs) through bio-reduction reactions of aqueous corresponding metal precursors mediated by extracts of aerial parts of R. hypocrateriformis, which act as both reducing and stabilizing agents, under microwave irradiation. UV-vis spectrophotometer, XRD, FT-IR, FESEM/TEM, TGA and EDAX analysis were used to characterize the obtained NPs. The formation of NPs is evident from their surface plasmon resonance peak observed at λ max =∼550, 450 and 500nm for Au, Ag and Au-Ag alloy NPs respectively. XRD pattern revealed that fcc structure, while FT-IR spectra signify the presence of phytochemicals adsorbed on NPs. Such a biofunctionalized NPs were characterized by their weight loss, 30% due to thermal degradation of plant phytochemicals observed in TG analysis. The spherical shape of Au, Ag and Au-Ag alloy NPs (∼10-50nm) is observed by FE-SEM/TEM images. EDAX analysis confirms the expected elemental composition. Moreover, these NPs showed enhanced antimicrobial, antioxidant, and anticancer activities, though it is more pronounced for Au-Ag alloy NPs, which is due to the combining effect of phytochemicals, Au and Ag metals. Thus, the biosynthesized NPs could be applied as effective growth inhibitors for various biomedical applications. Copyright © 2016 Elsevier Inc. All rights reserved.

  10. The adsorption of CO on charged and neutral Au and Au2: A comparison between wave-function based and density functional theory

    Science.gov (United States)

    Schwerdtfeger, Peter; Lein, Matthias; Krawczyk, Robert P.; Jacob, Christoph R.

    2008-03-01

    Quantum theoretical calculations are presented for CO attached to charged and neutral Au and Au2 with the aim to test the performance of currently applied density functional theory (DFT) by comparison with accurate wave-function based results. For this, we developed a compact sized correlation-consistent valence basis set which accompanies a small-core energy-consistent scalar relativistic pseudopotential for gold. The properties analyzed are geometries, dissociation energies, vibrational frequencies, ionization potentials, and electron affinities. The important role of the basis-set superposition error is addressed which can be substantial for the negatively charged systems. The dissociation energies decrease along the series Au+-CO, Au-CO, and Au--CO and as well as along the series Au2+-CO, Au2-CO, and Au2--CO. As one expects, a negative charge on gold weakens the carbon oxygen bond considerably, with a consequent redshift in the CO stretching frequency when moving from the positively charged to the neutral and the negatively charged gold atom or dimer. We find that the different density functional approximations applied are not able to correctly describe the rather weak interaction between CO and gold, thus questioning the application of DFT to CO adsorption on larger gold clusters or surfaces.

  11. Optical and microstructural properties of Au alloyed Al–O sputter deposited coatings

    Energy Technology Data Exchange (ETDEWEB)

    Figueiredo, N.M., E-mail: nuno.figueiredo@dem.uc.pt [SEG-CEMUC, Department of Mechanical Engineering, University of Coimbra (Portugal); Vaz, F.; Cunha, L. [Center of Physics, University of Minho (Portugal); Pei, Y.T.; De Hosson, J.T.M. [Materials Innovation Institute M2i, Department of Applied Physics, Zernike Institute for Advanced Materials, University of Groningen (Netherlands); Cavaleiro, A. [SEG-CEMUC, Department of Mechanical Engineering, University of Coimbra (Portugal)

    2016-01-01

    This research is focused on the microstructure and optical properties of an Al–O dielectric matrix incorporated with increasing Au contents up to 11 at.%. For the as-deposited coatings, the Au atoms appear to be alloyed into the amorphous oxide matrix, although a small fraction of Au atoms can also be incorporated in the form of very small nanoparticles (< 1–2 nm). Precipitation of Au nanoparticles was found in the coatings after annealing at increasing temperatures. Au clustering in the dielectric matrix was able to promote the surface plasmon resonance (SPR) effect, a desirable effect for applications in decorative and sensors fields. - Highlights: • Au-Al{sub 2}O{sub 3} nanocomposites with Au contents between 0 and 11 at.% were deposited by reactive co-sputtering. • For the as-deposited coatings, the Au atoms appear to be alloyed into the amorphous oxide matrix. • Precipitation of Au nanoparticles was found in the coatings after annealing at increasing temperatures. • Surface Plasmon Resonance effect was noted only after thermal annealing at 500 °C.

  12. Enhanced catalyst activity by decorating of Au on Ag@Cu2O nanoshell

    Science.gov (United States)

    Chen, Lei; Liu, Maomao; Zhao, Yue; Kou, Qiangwei; Wang, Yaxin; Liu, Yang; Zhang, Yongjun; Yang, Jinghai; Jung, Young Mee

    2018-03-01

    We successfully synthesized Au-decorated Ag@Cu2O heterostructures via a simple galvanic replacement method. As the Au precursor concentration increased, the density of the Au nanoparticles (NPs) on the Ag@Cu2O surface increased, which changed the catalytic activity of the Ag@Cu2O-Au structure. The combination of Au, Ag, and Cu2O exhibited excellent catalytic properties, which can further effect on the catalyst activity of the Ag@Cu2O-Au structure. In addition, the proposed Ag@Cu2O-Au nanocomposite was used to transform the organic, toxic pollutant, 4-nitrophenol (4-NP), into its nontoxic and medicinally important amino derivative via a catalytic reduction to optimize the material performance. The proposed Au-decorated Ag@Cu2O exhibited excellent catalytic activity, and the catalytic reduction time greatly decreased (5 min). Thus, three novel properties of Ag@Cu2O-Au, i.e., charge redistribution and transfer, adsorption, and catalytic reduction of organic pollutants, were ascertained for water remediation. The proposed catalytic properties have potential applications for photocatalysis and localized surface plasmon resonance (LSPR)- and peroxidase-like catalysis.

  13. Effects of TiO2 sol on the microstructure and properties of Au-Co coatings

    Science.gov (United States)

    Tay, See Leng; van Vliet, Jowin; Wang, Yuxin; Hou, Fengyan; Xiong, Chao; Gao, Wei

    2017-07-01

    Gold (Au) coatings are widely used for electrical contacts in devices, decoration and jewelry. However, the relatively low hardness and poor wear resistance of pure Au coatings lead to a short service life and limit their application. Ni is frequently used as an alloying element to enhance the hardness but it lowers the conductivity of Au coatings. In this research, Co was co-deposited as an alloying element with Au to improve its mechanical properties while maintaining conductivity. TiO2 sol in different concentrations was added to the Au-Co plating bath to further enhance the coating strength. Systematic studies including surface morphology, hardness, wear resistance and electrical conductivity have been carried out. Key results from nanoindentation tests demonstrated that the hardness of Au-Co-TiO2 composite coating was increased by 30% when compared to a pure Au-Co coating, while the electrical conductivity has been kept at the same level.

  14. Final Technical Report: First Principles Investigations for the Ensemble Effects of PdAu and PtAu Bimetallic Nanocatalysts

    Energy Technology Data Exchange (ETDEWEB)

    Ruqian Wu

    2012-05-18

    Bimetallic surfaces with tunable chemical properties have attracted broad attention in recent years due to their ample potential for heterogeneous catalysis applications. The local chemical properties of constituents are strongly altered from their parent metals by 'ligand effect', a term encompassing the influences of charge transfer, orbital rehybridization and lattice strain. In comparison to the aforementioned, the 'ensemble effect' associated with particular arrangements of the active constituents have received much less attention, despite their notable importance towards the determination of reactivity and selectivity of bimetallic catalysts. We performed theoretical studies for understanding the ensemble effects on bimetallic catalysis: (i) simulations for the formation of different ensembles on PdAu and PtAu nanoclusters; (ii) studies of the size, shape, and substrate dependence of their electronic properties; and (iii) simulations for model reactions such as CO oxidation, methanol, ethylene and water dehydrogenation on PdAu and PtAu nanoclusters. In close collaboration with leading experimental groups, our theoretical research elucidated the fundamentals of Au based bimetallic nanocatalysts.

  15. Filipino au pairs on the move

    DEFF Research Database (Denmark)

    Dalgas, Karina Märcher

    2016-01-01

    Most Filipina au pairs in Denmark send remittances back home, and for many, au pairing forms part of longer-term migration trajectories. This article explores how Filipina au pairs try to carve out a future for themselves abroad. It shows that they navigate within tight webs of financial interdep...

  16. Biological synthesis of Au nanoparticles using liquefied mash of cassava starch and their functionalization for enhanced hydrolysis of xylan by recombinant xylanase.

    Science.gov (United States)

    Zeng, Sumei; Du, Liangwei; Huang, Meiying; Feng, Jia-Xun

    2016-05-01

    Au nanoparticles (AuNPs) have shown the potential for a variety of applications due to their unique physical and chemical properties. In this study, a facile and affordable method for the synthesis of AuNPs via the liquefied mash of cassava starch has been described and the functionalized AuNPs by L-cysteine improved activity of recombinant xylanase was demonstrated. UV-Vis absorption spectroscopy, transmission electron microscopy, and zeta potential measurements were performed to characterize the AuNPs and monitor their synthesis. The presence of Au was confirmed by energy-dispersive X-ray spectroscopy (EDX) and the X-ray diffraction patterns showed that Au nanocrystals were face-centered cubic. The C=O stretching vibration in the Fourier transform infrared spectrum of AuNPs suggested that the hemiacetal C-OH of sugar molecules performed the reduction of Au³⁺ to Au⁰. The presence of C and O in the EDX spectrum and the negative zeta potential of AuNPs suggested that the biomolecules present in liquefied cassava mash were responsible for the stabilization of AuNPs. The surface of AuNPs was easily functionalized by L-cysteine, which improved the stability of AuNPs. Moreover, cysteine-functionalized AuNPs could significantly improve recombinant xylanase efficiency and stability.

  17. Direct electrochemical oxidation of S-captopril using gold electrodes modified with graphene-AuAg nanocomposites

    Science.gov (United States)

    Pogacean, Florina; Biris, Alexandru R; Coros, Maria; Lazar, Mihaela Diana; Watanabe, Fumiya; Kannarpady, Ganesh K; Al Said, Said A Farha; Biris, Alexandru S; Pruneanu, Stela

    2014-01-01

    In this paper, we present a novel approach for the electrochemical detection of S-captopril based on graphene AuAg nanostructures used to modify an Au electrode. Multi-layer graphene (Gr) sheets decorated with embedded bimetallic AuAg nanoparticles were successfully synthesized catalytically with methane as the carbon source. The two catalytic systems contained 1.0 wt% Ag and 1.0 wt% Au, while the second had a larger concentration of metals (1.5 wt% Ag and 1.5 wt% Au) and was used for the synthesis of the Gr-AuAg-1 and Gr-AuAg-1.5 multicomponent samples. High-resolution transmission electron microscopy analysis indicated the presence of graphene flakes that had regular shapes (square or rectangular) and dimensions in the tens to hundreds of nanometers. We found that the size of the embedded AuAg nanoparticles varied between 5 and 100 nm, with the majority being smaller than 20 nm. Advanced scanning transmission electron microscopy studies indicated a bimetallic characteristic of the metallic clusters. The resulting Gr-AuAg-1 and Gr-AuAg-1.5 samples were used to modify the surface of commonly used Au substrates and subsequently employed for the direct electrochemical oxidation of S-captopril. By comparing the differential pulse voltammograms recorded with the two modified electrodes at various concentrations of captopril, the peak current was determined to be well-defined, even at relatively low concentration (10−5 M), for the Au/Gr-AuAg-1.5 electrode. In contrast, the signals recorded with the Au/Gr-AuAg-1 electrode were poorly defined within a 5×10−6 to 5×10−3 M concentration range, and many of them overlapped with the background. Such composite materials could find significant applications in nanotechnology, sensing, or nanomedicine. PMID:24596464

  18. Synthesis of Au microwires by selective oxidation of Au–W thin-film composition spreads

    Directory of Open Access Journals (Sweden)

    Sven Hamann, Hayo Brunken, Steffen Salomon, Robert Meyer, Alan Savan and Alfred Ludwig

    2013-01-01

    Full Text Available We report on the stress-induced growth of Au microwires out of a surrounding Au–W matrix by selective oxidation, in view of a possible application as 'micro-Velcro'. The Au wires are extruded due to the high compressive stress in the tungsten oxide formed by oxidation of elemental W. The samples were fabricated as a thin-film materials library using combinatorial sputter deposition followed by thermal oxidation. Sizes and shapes of the Au microwires were investigated as a function of the W to Au ratio. The coherence length and stress state of the Au microwires were related to their shape and plastic deformation. Depending on the composition of the Au–W precursor, the oxidized samples showed regions with differently shaped Au microwires. The Au48W52 composition yielded wires with the maximum length to diameter ratio due to the high compressive stress in the tungsten oxide matrix. The values of wire length (35 μm and diameter (2 μm achieved at the Au48W52 composition are suitable for micro-Velcro applications.

  19. Evolution of Self-Assembled Au NPs by Controlling Annealing Temperature and Dwelling Time on Sapphire (0001)

    Science.gov (United States)

    Lee, Jihoon; Pandey, Puran; Sui, Mao; Li, Ming-Yu; Zhang, Quanzhen; Kunwar, Sundar

    2015-12-01

    Au nanoparticles (NPs) have been utilized in a wide range of device applications as well as catalysts for the fabrication of nanopores and nanowires, in which the performance of the associated devices and morphology of nanopores and nanowires are strongly dependent on the size, density, and configuration of the Au NPs. In this paper, the evolution of the self-assembled Au nanostructures and NPs on sapphire (0001) is systematically investigated with the variation of annealing temperature (AT) and dwelling time (DT). At the low-temperature range between 300 and 600 °C, three distinct regimes of the Au nanostructure configuration are observed, i.e., the vermiform-like Au piles, irregular Au nano-mounds, and Au islands. Subsequently, being provided with relatively high thermal energy between 700 and 900 °C, the round dome-shaped Au NPs are fabricated based on the Volmer-Weber growth model. With the increased AT, the size of the Au NPs is gradually increased due to a more favorable surface diffusion while the density is gradually decreased as a compensation. On the other hand, with the increased DT, the size and density of Au NPs decrease due to the evaporation of Au at relatively high annealing temperature at 950 °C.

  20. Development in Belgium of pinhole tomo-scintigraphy and of its applications to human and to small animals; Developpement en Belgique de la tomoscintigraphie stenopeique et de ses applications a l'homme et au petit animal

    Energy Technology Data Exchange (ETDEWEB)

    Seret, A. [Liege Univ., Institut de Physique, Imagerie Medicale Experimentale (Belgium)

    2006-06-15

    In Belgium, several researchers have been highly active in developing pinhole tomo-scintigraphy and have sometimes made a pioneer work. Their contributions concern as well the methodology of the technique as its applications to human and small animals. Reconstruction algorithms, of analytic and iterative type, have been developed and validated. They can reconstruct data obtained along circular, half-circular and non-circular acquisition orbits, the camera head being eventually tilted. A very performing method has been elaborated to determine the seven geometric parameters of the acquisition that are needed for an optimal reconstruction. The use of pinhole tomo-scintigraphy for thyroid exploration seems to be born in Belgium and a few validation studies were conducted in the country. Potentials of pinhole tomography application to parathyroid or bone scintigraphy have also been considered. Finally, some research groups are using pinhole tomo-scintigraphy for small animal studies. (author)

  1. d + Au hadron correlation measurements at PHENIX

    Energy Technology Data Exchange (ETDEWEB)

    Sickles, Anne M., E-mail: anne@bnl.gov

    2014-06-15

    In these proceedings, we discuss recent results from d + Au collisions in PHENIX ridge related measurements and their possible hydrodynamic origin. We present the v{sub 2} at midrapidity and measurements of the pseudorapidity dependence of the ridge, distinguishing between the d-going and Au-going directions. We investigate the possible geometrical origin by comparing v{sub 2} in d + Au to that in p + Pb, Au + Au and Pb + Pb collisions. Future plans to clarify the role of geometry in small collision systems at RHIC are discussed.

  2. Decay spectroscopy of $^{178}$Au

    CERN Document Server

    Whitmore, B

    In this thesis, the neutron-deficient nucleus $^{178}$Au is investigated through decay spectroscopy. Si and HPGe detectors were used to analyse the decay radiation of $^{178}$Au and its daughter nuclei. Previous studies have been unable to distinguish decay radiation from different isomeric states of this nucleus. This thesis represents the first time such isomeric discrimination has been achieved, and presents tentative spin assignments of both the ground state and an isomer. The neutron-deficient gold isotopes are an area of interest for the study of shape coexistence. This is the phenomenon exhibited by nuclei able to exist at a number of close lying energy minima, each reflecting a distinct type of deformation. It is hoped that studies such as this can help identify the evolution of nuclear deformation in this region of the nuclear chart.

  3. L’apprentissage au CERN

    CERN Document Server

    Staff Association

    2016-01-01

    En 1961, sur la base du constat que l’évolution du marché du travail nécessitait un besoin croissant de personnel qualifié, le 1er accord entre la République et canton de Genève et le CERN fut signé. Cet accord avait notamment pour objet la formation professionnelle de jeunes électroniciens et techniciens de laboratoires en physique. Le CERN, acteur local économique d’importance, soulignait par cet accord sa volonté de participer au développement économique et social local. Le 1er apprenti arriva au CERN en 1965. En 1971, le centre d’apprentissage fut créé ; il accueille aujourd’hui plus d’une vingtaine d’apprentis au total, à raison d’environ six nouveaux apprentis chaque année. Cet apprentissage est dédié aux jeunes âgés e...

  4. Un multi-outil adapté au parcours cognitif de l’étudiant en traduction spécialisée : application à la biomédecine

    Directory of Open Access Journals (Sweden)

    Sylvie Boudreau

    2007-01-01

    Full Text Available Le site BiomeTTico vise à répondre aux difficultés soulevées par l’apprentissage de la traduction spécialisée (biomédecine. Il s’agit d’un multi-outil informatique d’aide à l’enseignement de la traduction biomédicale au baccalauréat et aux cycles supérieurs, conçu en fonction d’une approche cognitive de l’apprentissage et de la pratique de la traduction. Prenant en compte différentes catégories d’utilisateurs, il se veut également une plate-forme de valorisation des travaux de recherche, notamment au 2e et au 3ecycle, et, dans une certaine mesure, un site de référence pour les traducteurs professionnels. L’organisation du site est fondée sur des principes d’utilisabilité, d’interactivité et de participation collaborative au contenu, adaptés à un contexte pédagogique. Il intègre différents produits de la recherche menée ces dernières années et il est appelé à évoluer dans le temps. Bien que son contenu soit spécifique à la biomédecine, sa structure est réutilisable dans d’autres contextes d’enseignement de la traduction.

  5. Utilisation de dispositifs a transfert de charge pour la detection de muons cosmiques dans un contexte de tomographie

    Science.gov (United States)

    Marion-Ouellet, Laurence Olivier

    775 mum respectively, which translates to 28 000 and 76 000 electron-hole pairs as signal for the two thicknesses. All the results obtained through Geant4 are consistent with the known theory of energy deposits in thin semiconductor materials. A practical experimentation was also considered, using an astronomical camera DMK51 AU02.AS to capture a series of images hidden from light with the camera turned towards the sky. The pixels presenting a high intensity are considered to be the consequence of the passage of a muon. The expected rate of detection according to the size of the detector was 0.372 muons per minute but the results were 0.1578 muons per minute for data taken inside Polytechnique and 0.1615 for images taken outside. Therefore, the presence of about two meters of concrete above the camera does not significantly affect the detectable muon flux. However, the ratio of 40 % between expected signal and the observations is explained by the small size of the sensitive area of a pixel when compared to its total size. Components such as electrodes and differently doped silicon occupy a certain area in the pixel causing it, in the eyes of the muon, to be much smaller. A smaller pixel will ensure a smaller expected muon flux. Also, the possibility that the energy deposition is simply too small in some cases to be detected is also studied in the results section and solutions to resolve this problem are presented in the conclusion.

  6. Reaction mechanisms for the CO oxidation on Au/CeO(2) catalysts: activity of substitutional Au(3+)/Au(+) cations and deactivation of supported Au(+) adatoms.

    Science.gov (United States)

    Camellone, Matteo Farnesi; Fabris, Stefano

    2009-08-05

    Density functional theory calculations that account for the on-site Coulomb interaction via a Hubbard term (DFT+U) reveal the mechanisms for the oxidation of CO catalyzed by isolated Au atoms as well as small clusters in Au/CeO(2) catalysts. Ceria (111) surfaces containing positively charged Au ions, either as supported Au(+) adatoms or as substitutional Au(3+) ions, are shown to activate molecular CO and to catalyze its oxidation to CO(2). In the case of supported single Au(+) adatoms, the limiting rate for the CO oxidation is determined by the adsorbate spillover from the adatom to the oxide support. The reaction then proceeds with the CO oxidation via lattice oxygen and O vacancy formation. These vacancies are shown to readily attract the supported Au(+) adatoms and to turn them into negatively charged Au(delta-) adspecies that deactivate the catalyst, preventing further CO adsorption. Au(3+) ions dispersed into the ceria lattice as substitutional point defects can instead sustain a full catalytic cycle consisting of three individual steps maintaining their activity along the reaction process: Au cations in Au(x)Ce(1-x)O(2) systems promote multiple oxidations of CO without any activation energy via formation of surface O vacancies. Molecular oxygen adsorbs at these vacancies and forms O adspecies that then catalyze the oxidation of molecular CO, closing the catalytic cycle and recovering the stoichiometric Au(x)Ce(1-x)O(2) system. The interplay between the reversible Ce(4+)/Ce(3+) and Au(3+)/Au(+) reductions underpins the high catalytic activity of dispersed Au atoms into the ceria substrate. It is shown that the positive oxidation state of the substitutional Au ions is retained along the catalytic cycle, thus preventing the deactivation of Au(x)Ce(1-x)O(2) catalysts in operation conditions. Finally, although a single Au(+) adatom bound to an O vacancy is shown to deactivate during CO oxidation, the calculations predict that the reactivity of gold nanoparticles

  7. Enhanced quantum cutting luminescence by Au nanorods through improving radiative transition rate

    Science.gov (United States)

    Zheng, Biao; Lin, Lin; Feng, Zhuohong; Huang, Lili; Zhuang, Luoqing; Wang, Zhezhe; Zheng, Zhiqiang

    2017-11-01

    Quantum cutting (QC) phosphor β-NaYF4:Tb3+, Yb3+ nanoparticles (NPs) are decorated with Au nanorods (NRs). By tailoring Au NRs longitudinal plasmon resonance to match the emission wavelength of Yb3+ ion, plasmon-enhanced near-infrared (NIR) QC luminescence is achieved through improving Yb3+ ion's radiative transition rate. The decay curves of Yb3+ ion in β-NaYF4:Tb3+, Yb3+ NPs decorated with Au NRs further confirm the improvement of radiative transition rate. The influence of Au NRs concentration on QC luminescence is also investigated, and the results show that the optimal concentration of Au NRs is 0.12% with the maximum enhancement factor about 3. Our study may not only path the way to achieve simultaneous excitation and emission enhancement of QC luminescence, but also provide a potential application as QC layer to silicon-based solar cells.

  8. Single-crystal Au microflakes modulated by amino acids and their sensing and catalytic properties.

    Science.gov (United States)

    Li, Mingjie; Wu, Xiaochen; Zhou, Jiyu; Kong, Qingshan; Li, Chaoxu

    2016-04-01

    Single-crystal Au microflakes with the planar area over 10(3)μm(2) (i.e. being accessible to the human eye resolution) were synthesized in an environment-friendly route by directing two-dimensional growth of Au nanocrystals into macroscopic scales with amino acids as both reducing agents and capping agents. Side groups of amino acids were found to be a determinant parameter to tune the dimension and size of Au single crystals. The successful synthesis of Au microflakes provides an unprecedented opportunity to bridge nanotechnology and macroscopic devices, and hereby to start a new scenario of exploring their unique properties and applications in optoelectronic devices and bio-sensing fields across multiple length scales. For example, Au microflakes respond to air humidity upon depositing on films of chitin nanofibrils, and sense various physiological molecules as electrode materials of biosensors. Copyright © 2016 Elsevier Inc. All rights reserved.

  9. Theoretical study on the photocatalytic properties of graphene oxide with single Au atom adsorption

    Science.gov (United States)

    Ju, Lin; Dai, Ying; Wei, Wei; Li, Mengmeng; Jin, Cui; Huang, Baibiao

    2018-03-01

    The photocatalytic properties of graphene oxide (GO) with single Au atom adsorption are studied via the first-principles calculations based on the density functional theory. The present study addresses the origin of enhancement in photocatalytic efficiency of GO derived from single Au atom depositing. Compared with the clean one, the work function of the single Au atom adsorbed GO is lowered due to the charge transfer from Au to GO, indicating enhanced surface activity. The Au atom plays as an electron trapping center and a mediating role in charge transfer from photon excited GO to target species. The photogenerated electron-hole pairs can be separated effectively. For the GO configuration with atomic Au dispersion, there are some states introduced in the band gap, which are predominantly composed of Au 6s states. Through the in-gap state, the photo-generated electron transfer from the valence band of clean GO to the conductive band more easily. In addition, the reduction of the gap in the system is also presented in the current work, which indicates that the single Au atom adsorption improves light absorption for the GO based photocatalyst. These theoretical results are valuable for the future applications of GO materials as photocatalyst for water splitting.

  10. In Vitro Study of Influence of Au Nanoparticles on HT29 and SPEV Cell Lines

    Science.gov (United States)

    Pavlovich, Elena; Volkova, Nataliia; Yakymchuk, Elena; Perepelitsyna, Olena; Sydorenko, Michail; Goltsev, Anatoliy

    2017-08-01

    Cell culture models are excellent tools for potential toxicity of nanoparticles and fundamental investigations in cancer research. Thus, information about AuNP potential toxicity and effects on human health is necessary for the use of nanomaterials in clinical settings. The aim of our research is to examine the effects of AuNPs on the epithelial origin cell lines: continuous and oncogenic. Embryonic porcine kidney epithelial inoculated (SPEV) cell line and colorectal carcinoma cell line (HT29) were used. In the test cultures, the cell proliferation, necrosis/apoptosis, and multicellular spheroids generation were evaluated. We demonstrated that AuNP concentrations of 6-12 μg/ml reduced the proliferation of SPEV and HT29 cells and increased the cell number at early and late stages of apoptosis and necrosis. It was shown that small concentrations of AuNPs (1-3 μg/ml) stimulate multicellular spheroid formation by HT29 and SPEV cells. However, higher AuNP concentrations (6-12 μg/ml) had both cytotoxic and anti-cohesive effects on cell in suspension. The large sensitiveness to the action of AuNPs was shown by the line of HT29 (6 μg/ml) as compared to the SPEV cells (12 μg/ml). This experimental study of the effect of AuNPs on SPEV and HT29 cell lines will justify their further application in AuNP-mediated anticancer treatment.

  11. La transmission au Forem, terreau fertile pour l'organisation apprenante ?

    OpenAIRE

    Boulet, Gaëlle; Vos, Michèle

    2012-01-01

    Atelier 34 : Organisation apprenante et coopérative; Cette analyse des pratiques de transmission menées dans une institution publique de l'emploi et de la formation, Le Forem, est le fruit des réflexions de professionnels sur leur propre activité. Contexte, enjeux et approche menée en matière de transfert de savoirs sont situés dans le cadre de la gestion des connaissances. Ces transferts de savoirs renvoient à des dynamiques individuelles et collectives et mettent en oeuvre des méthodes lian...

  12. Transport characteristics in Au/pentacene/Au diodes

    Science.gov (United States)

    Hayashi, Toshiaki; Naka, Akiyoshi; Hiroki, Masanobu; Yokota, Tomoyuki; Someya, Takao; Fujiwara, Akira

    2018-03-01

    We have used scanning and transmission electron microscopes (SEM and TEM) to study the structure of a pentacene thin film grown on a Au layer with and shown that it consists of randomly oriented amorphous pentacene clusters. We have also investigated the transport properties of amorphous pentacene in a metal-semiconductor-metal (MSM) diode structure and shown that the current is logarithmically proportional to the square root of the applied voltage, which indicates that transport occurs as the result of hopping between localized sites randomly distributed in space and energy.

  13. Assessment, modelization and analysis of {sup 106} Ru experimental transfers through a freshwater trophic system; Evaluation, modelisation et analyse des transferts experimentaux du {sup 106}Ru au sein d`un reseau trophique d`eau douce

    Energy Technology Data Exchange (ETDEWEB)

    Vray, F.

    1994-11-24

    Experiments are carried out in order to study {sup 106} RU transfers through a freshwater ecosystem including 2 abiotic compartments (water and sediment) and 3 trophic levels (10 species). Experimental results are expressed mathematically so as they can be included into a global model which is then tested in two different situations. The comparison of the available data concerning the in situ measured concentrations to the corresponding calculated ones validates the whole procedure. Analysis of the so validated results lightens ruthenium distribution process in the environment. The rare detection of this radionuclide in organisms living in areas contaminated by known meaningful releases can be explained by a relativity high detection limit and by a slight role of the sediment as a secondary contamination source. (author). 78 figs., 18 tabs.

  14. Strontium and caesium transport in unsaturated soil from Chernobyl Pilot Site under steady flow conditions; Transfert de radioelements en zone non saturee. Etude experimentale et modelisation appliquees au Site Pilote de Tchernobyl

    Energy Technology Data Exchange (ETDEWEB)

    Szenknect, St

    2003-10-15

    This work is devoted to the quantification and the identification of the predominant processes involved in strontium and caesium transport in unsaturated soil from Chernobyl Pilot Site under steady flow conditions. The transport and fate of radionuclides in the subsurface is affected by various physical and chemical processes including advective and diffusive transport as well as chemical and biological transformations. Laboratory experiments and the use of a multiple tracer approach allow to isolate the contributions of each elementary process and to control the physico-chemical conditions in the system. To be more representative of the field conditions, we decided to perform column miscible displacement experiments. We perform batch and flow-through reactor experiments to characterize the radionuclides sorption mechanisms. Miscible displacement experiments within homogeneous columns and modeling allow to characterize the hydrodynamic properties of the soil and to describe the radionuclides behaviour under dynamic conditions at different water contents. We show that the water content of porous media affect the transport behaviour of inert and strongly sorbing radionuclides. Our results demonstrate that a parametrized transport model that was calibrated under completely saturated conditions was not able to describe the advective-dispersive transport of reactive solutes under unsaturated steady state conditions. Under our experimental conditions, there is no effect of a decrease of the mean water content on the sorption model parameters, but the transport parameters are modified. We established for the studied soil the relation between hydrodynamic dispersion and water content and the relation between pore water velocity and water content. (author)

  15. Global dynamics of shaft lines of turbo-machineries coupled to surrounding fluids: application to the case of fluid sheets; Dynamique globale des lignes d'arbres de turbomachines couplees aux fluides environnants: application au cas des lames fluides

    Energy Technology Data Exchange (ETDEWEB)

    Lornage, D.

    2001-12-15

    Shaft lines of turbo-machineries have to stand increasing reliability, efficiency and safety requirements. A precise modeling of the rotating parts with all possible coupling has become necessary. In this context, this work aims to develop a global modeling of rotating wheel/shaft system inside a surrounding fluid in order to foresee its dynamical behaviour. The use and advantage of Eulerian, Lagrangian and mixed (arbitrary Lagrangian Eulerian - ALE) formulations is recalled first. A bibliographic synthesis of the classical techniques used in structure mechanics and of coupling techniques for rotating machines is presented. The coupling technique retained is presented. It uses fluid and structure models independently developed and validated. The structure domain is discretized by the finite-element method. The fluid domain is discretized by the finite-difference method taking into consideration the hypotheses linked with thin films. A modal base projection combined with a mesh at the fluid-structure interface allows an efficient, adaptable and evolutive coupling. Finally, the method is applied to 3 test-cases. The first two ones comprise a shaft/disc system coupled to a fluid sheet between the disc and the casing and to an hydrodynamic bearing. Both cases allow a first validation of the coupling method. The third case aims to study a structure closer to a real system made of a shaft and a wheel coupled to a fluid sheet between a flange and a casing. These three applications allow to show the trends linked with the fluid effects and the coupling between the flexible sub-parts of the structure. (J.S.)

  16. Becoming independent through au pair migration

    DEFF Research Database (Denmark)

    Dalgas, Karina Märcher

    2015-01-01

    . This article argues that, despite this critique, au pairing does play an important formative role for young Filipinas because it opens up for experiences abroad that enable them to be recognised as independent adults in Philippine society. Rather than autonomy, however, au pairs define their independence......Over the past decade, growing numbers of young Filipinas have entered Denmark on the au pair scheme. While its official aim is to broaden the cultural horizons of youth, researchers generally view Filipina au pairing as a form of labour migration using au pairs as inexpensive domestic workers...... in terms of their capacity to assume responsibility for others, thereby achieving a position of social respect. Based on ethnographic fieldwork in Denmark and the Philippines, this article explores how young Filipinas use the social, economic, and cultural resources they gain from their au pair stay abroad...

  17. L’olivier au Maroc

    OpenAIRE

    El Mouhtadi Issam; Agouzzal Mohamed; Guy François

    2014-01-01

    L’olivier est une culture traditionnelle sur le pourtour de la Méditerranée. Il est donc naturel de trouver cet arbre au Maroc où il est présent depuis des siècles. Cultivé surtout traditionnellement jusqu’à ses dernières années, il fait l’objet maintenant d’un plan de valorisation très ambitieux pour non seulement garder le Royaume à son niveau actuel (2e producteur mondial pour l’olive de conserve et 6e pour l’huile d’olive) mais pour conq...

  18. Transferts de masse et de chaleur entre une gouttelette d'un liquide hygroscopique et l'air humide

    OpenAIRE

    Pelletret , R.; Sylvain , J.-D.

    1985-01-01

    Cette étude s'insère dans le cadre des interactions entre un liquide hygroscopique et l'air humide. Par définition, une goutte d'un tel liquide capte les molécules de vapeur d'eau et s'échauffe du fait de la chaleur libérée, à sa surface, par condensation. Des expérimentations, mesurant en régime transitoire la température de gouttelettes de chlorure de lithium et de soude, ont permis de valider, pour nos applications, la corrélation de Ranz et Marshall. Un modèle aux différences finies, de l...

  19. Au-Protected Ag Core/Satellite Nanoassemblies for Excellent Extra-/Intracellular Surface-Enhanced Raman Scattering Activity.

    Science.gov (United States)

    Zhang, Zhiqiang; Bando, Kazuki; Taguchi, Atsushi; Mochizuki, Kentaro; Sato, Kazuhisa; Yasuda, Hidehiro; Fujita, Katsumasa; Kawata, Satoshi

    2017-12-20

    Silver nanoparticles (AgNPs) and their assembled nanostructures such as core/satellite nanoassemblies are quite attractive in plasmonic-based applications. However, one biggest drawback of the AgNPs is the poor chemical stability which also greatly limits their applications. We report fine Au coating on synthesized quasi-spherical silver nanoparticles (AgNSs) with few atomic layers to several nanometers by stoichiometric method. The fine Au coating layer was confirmed by energy-dispersive X-ray spectroscopy elemental mapping and aberration-corrected high-angle annular dark-field scanning transmission electron microscopy. The optimized minimal thickness of Au coating layer on different sized AgNSs (22 nm Ag@0.9 nm Au, 44 nm Ag@1.8 nm Au, 75 nm Ag@2.9 nm Au, and 103 nm Ag@0.9 nm Au) was determined by extreme chemical stability tests using H 2 O 2 , NaSH, and H 2 S gas. The thin Au coating layer on AgNSs did not affect their plasmonic-based applications. The core/satellite assemblies based on Ag@Au NPs showed the comparable SERS intensity and uniformity three times higher than that of noncoated Ag core/satellites. The Ag@Au core/satellites also showed high stability in intracellular SERS imaging for at least two days, while the SERS of the noncoated Ag core/satellites decayed significantly. These spherical Ag@Au NPs can be widely used and have great advantages in plasmon-based applications, intracellular SERS probes, and other biological and analytical studies.

  20. Predicted Habitat Suitability for Montipora Corals in the Au'au Channel Region

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This raster denotes predicted habitat suitability for Montipora in the Au'au Channel region. Maximum Entropy (MaxEnt) modeling software was used to create this...

  1. Predicted Habitat Suitability for All Mesophotic Corals in the Au'au Channel Region

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This raster denotes predicted habitat suitability for all mesophotic corals in the Au'au Channel region. Maximum Entropy (MaxEnt) modeling software was used to...

  2. Predicted Habitat Suitability for Leptoseris in the Au'au Channel Region

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This raster denotes predicted habitat suitability for Leptoseris in the Au'au Channel region. Maximum Entropy (MaxEnt) modeling software was used to create this...

  3. Predicted Habitat Suitability for Porites in the Au'au Channel Region

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This raster denotes predicted habitat suitability for Porites in the Au'au Channel region. Maximum Entropy (MaxEnt) modeling software was used to create this...

  4. Predicted Habitat Suitability for Leptoseris Corals in the Au'au Channel Region

    Data.gov (United States)

    National Oceanic and Atmospheric Administration, Department of Commerce — This raster denotes predicted habitat suitability for Leptoseris in the Au'au Channel region. Maximum Entropy (MaxEnt) modeling software was used to create this...

  5. Synthesis of nir-sensitive Au-Au{sub 2}S nanocolloids for drug delivery

    Energy Technology Data Exchange (ETDEWEB)

    Ren, L.; Chow, G.M

    2003-01-15

    Near IR (NIR) sensitive Au-Au{sub 2}S nanocolloids were prepared by mixing HAuCl{sub 4} and Na{sub 2}S in aqueous solutions. An anti-tumor drug, cis-platin, was adsorbed onto Au-Au{sub 2}S nanoparticle surface via the 11-mercaptoundecanoic acid (MUA) layers. The results show that the degree of adsorption of cis-platin onto Au-Au{sub 2}S nanoparticles was controlled by the solution pH value, and the drug release was sensitive to near-infrared irradiation. The cis-platin-loaded Au-Au{sub 2}S nanocolloids can be potentially applied as NIR activated drug delivery carrier.

  6. Split resonance modes of a AuBRC plasmonic nanosystem caused by the coupling effect

    International Nuclear Information System (INIS)

    Ni, Yuan; Kan, Caixia; Xu, Haiying; Wang, Changshun

    2016-01-01

    A plasmonic nanosystem can give rise to particular optical responses due to a coupling effect. In this work, we investigate the optical properties and field distributions of a novel ‘matrioska’ nanocavity structure composed of a Au nanorod (AuNR) within a nanobox (AuNB) via finite-difference time-domain (FDTD) simulation. This nanocavity can be fabricated by a two-step wet-chemical method. The multiple SPR modes of optical spectrum for nanocavity are caused by the strong interaction between the AuNR-core and AuNB-shell when the incident light is perpendicular or parallel to the long axis of the Au box/rod nanocavity (AuBRC). The SPR modes are known as the dipole–dipole bonding resonance mode in the lower-energy region and the antibonding resonance mode in the higher-energy region. It is proposed that AuBRC can escape the orientation confinement of AuNR because the multiple modes occur and provide a potential application for the enhancement of the photoluminescence signal. Additionally, the SPR modes red-shift with increasing the offset of the AuNR-core, whereas the SPR mode dramatically blue-shifts when the conductive coupling is formed. The intense ‘hot-spot’ could be induced within a small interaction region in the conductive coupled system. The SPR line-shape of high quality would also be promoted. The SPR is highly sensitive to the medium, which is promising in the sensing and detecting devices. (paper)

  7. Femmes, migration et droits au Mali et au Sénégal | IDRC ...

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

    Cette subvention permet au Groupe de recherche sur les femmes et les lois au Sénégal (GREFELS) de lever ces insuffisances. Les chercheurs vont analyser des stratégies migratoires des jeunes filles et des femmes dans les deux pays, étudier les conditions de travail des travailleuses domestiques au Sénégal, ...

  8. Au-Pt-Au nanoraspberry structures used for mercury ion detection

    Science.gov (United States)

    Huang, Jiang-Hao; Huang, Shuai; Wen, Xiaoyan; Li, Min; Lu, Haifei

    2017-12-01

    Detection of Hg2+ with high sensitivity is of great significance in the biochemical sensing field. Quantitative of Hg2+ was realized based on the influence of Hg2+ on the UV-vis absorption performance of Au-Pt-Au core-shell nanoraspberry (APA)-rhodamine-6G (R6G) structure. First, APA sol was added into R6G indicator solution and the UV-vis absorption signal intensity of R6G was evidently promoted. The signal intensity monotonously increased as more APA sol was added. However, when HgCl2 solution was introduced, the signal intensity declined. A linear relationship between Hg2+ concentration and signal intensity at 527 nm was revealed, based on which quantitative determination of Hg2+ could be realized. Hg2+ detection sensitivity was measured to be 0.031 a.u./M with a limit of detection of 10-7 M and the response time was 20 s. A high Hg2+ detection selectivity over Cu2+, Na+, Li+, and K+ was demonstrated. Due to its simplicity and high sensitivity, the proposed method could find an extensive application prospect in the Hg2+ detection field.

  9. Phospholipid Encapsulated AuNR@Ag/Au Nanosphere SERS Tags with Environmental Stimulus Responsive Signal Property.

    Science.gov (United States)

    Su, Xueming; Wang, Yunqing; Wang, Wenhai; Sun, Kaoxiang; Chen, Lingxin

    2016-04-27

    Surface-enhanced Raman scattering (SERS) tags draw much attention due to the ultrasensitivity and multiplex labeling capability. Recently, a new kind of SERS tags was rationally designed by encapsulating metal nanoparticles with phospholipid bilayers, showing great potential in theranostics. The lipid bilayer coating confers biocompatibility and versatility to changing surface chemistry of the tag; however, its "soft" feature may influence SERS signal stability, which is rarely investigated. Herein, we prepared phospholipid-coated AuNR@Ag/Au nanosphere SERS tags by using three different kinds of Raman reporters, i.e., thio-containing 4-nitrothiophenol (NT), nitrogen-containing hydrophobic chromophore cyanine 7 monoacid (Cy7), and alkyl chain-chromophore conjugate 1,1'-dioctadecyl-3,3,3',3'-tetramethylindodicarbocyanine (DiD). It was found that signal responses were different upon additional stimulation which the tags may encounter in theranostic applications including the presence of detergent Triton X-100, lipid membrane, and photothermal treatment. Living-cell imaging also showed signal changing distinction. The different SERS signal performances were attributed to the different Raman reporter releasing behaviors from the tags. This work revealed that Raman reporter structure determined signal stability of lipid-coated SERS tags, providing guidance for the design of stimulus responsive tags. Moreover, it also implied the potential of SERS technique for real time drug release study of lipid based nanomedicine.

  10. 22 CFR 62.31 - Au pairs.

    Science.gov (United States)

    2010-04-01

    ... programs under which foreign nationals are afforded the opportunity to live with an American host family and participate directly in the home life of the host family. All au pair participants provide child care services to the host family and attend a U.S. post-secondary educational institution. Au pair...

  11. Study of Au+Au relativistic collisions with the Fopi-Phase I detector; Etude des collisions relativistes Au+Au avec le detecteur Fopi-Phase I

    Energy Technology Data Exchange (ETDEWEB)

    Dupieux, P.

    1995-01-01

    Au+Au relativistic collisions, in a 100-1000 MeV energy domain per nucleon, are described. Experiments have been carried out with the SIS accelerator at GSI/Darmstadt. Data are analysed with the FOPI-phase I detector. These data are compared with IQMD model (Isospin Quantum Molecular Dynamics) Predictions. (S.G). 80 refs., 77 figs., 5 tabs.

  12. AU-EU “Strategic Partnership”

    DEFF Research Database (Denmark)

    Rodt, Annemarie Peen; Okeke, Jide

    2013-01-01

    This article appraises strategic partnership between the African Union (AU) and European Union (EU). It examines the context and nature of AU and EU security relations and explores the conditions under which partnership has a positive impact in this regard. This includes an evaluation...

  13. Travailler avec Windows 7 au CERN (FR)

    CERN Multimedia

    CERN. Geneva

    2010-01-01

    Vue d'ensemble des nouveaux concepts et des changements dans l'interface utilisateur survenus dans Windows 7 depuis les versions antérieures de Windows (XP ou Vista). La mise à disposition de Windows 7 au CERN et son intégration dans l’infrastructure de Windows au CERN seront présentées.

  14. English for au pairs the au pair's guide to learning English

    CERN Document Server

    Curtis, Lucy

    2014-01-01

    English for Au Pairs has interlinked stories about a group of au pairs new to England. Marta, an 18-year-old from Poland arrives in the UK to work as an au pair. Throughout her year-long stay she has many different experiences - some bad, some good - but with the support of her host family she finds new friends and improves her English. English for Au Pairs offers insight into the joys and difficulties of being an au pair while at the same time reinforcing English language learning through grammar explanations and exercises.

  15. From the Au nano-clusters to the nanoparticles on 4H-SiC (0001).

    Science.gov (United States)

    Li, Ming-Yu; Zhang, Quanzhen; Pandey, Puran; Sui, Mao; Kim, Eun-Soo; Lee, Jihoon

    2015-09-10

    The control over the configuration, size, and density of Au nanoparticles (NPs) has offered a promising route to control the spatial confinement of electrons and photons, as a result, Au NPs with a various configuration, size and density are witnessed in numerous applications. In this work, we investigate the evolution of self-assembled Au nanostructures on 4H-SiC (0001) by the systematic variation of annealing temperature (AT) with several deposition amount (DA). With the relatively high DAs (8 and 15 nm), depending on the AT variation, the surface morphology drastically evolve in two distinctive phases, i.e. (I) irregular nano-mounds and (II) hexagonal nano-crystals. The thermal energy activates adatoms to aggregate resulting in the formation of self-assembled irregular Au nano-mounds based on diffusion limited agglomeration at comparatively low annealing temperature, which is also accompanied with the formations of hillocks and granules due to the dewetting of Au films and surface reordering. At high temperature, hexagonal Au nano-crystals form with facets along {111} and {100} likely due to anisotropic distribution of surface energy induced by the increased volume of NPs. With the small DA (3 nm), only dome shaped Au NPs are fabricated along with the variation of AT from low to elevated temperature.

  16. Fabrication of BSA@AuNC-Based Nanostructures for Cell Fluoresce Imaging and Target Drug Delivery.

    Science.gov (United States)

    Ding, Caifeng; Xu, Yujuan; Zhao, Yanan; Zhong, Hua; Luo, Xiliang

    2018-03-14

    Drug delivery which can offer efficient and localized drug transportation together with imaging capabilities is highly demanded in the development of cancer theranostic approaches. Herein, we report the construction of bovine serum albumin (BSA) gold nanoclusters (BSA@AuNCs) for cell fluoresce imaging and target drug delivery. BSA@AuNCs were modified with cyclic arginine-glycine-aspartate with the product RGD-BSA@AuNCs to enhance cell internalization of the nanoclusters. Furthermore, doxorubicin hydrochloride or doxorubicin (DOX), a widely used chemotherapy drug, was also used to modify RGD-BSA@AuNCs. The final design of the DOX/RGD-BSA@AuNC system was constructed through the disulfide bond. The physical microstructure and biological characterization of the BSA@AuNCs were realized through high-resolution transmission electron microscopy and confocal laser fluorescence microscopy. As the disulfide bonds were cleaved by glutathione in cancer cells, DOX-SH molecules were released from the nanosystem to inhibit the growth of cancer cells. The as-prepared DOX/RGD-BSA@AuNC system can be used not only to deliver drug but also to achieve the antitumor effect by in vivo imaging, demonstrating its promising applications in cancer treatment.

  17. Porous α-Fe2O3 decorated by Au nanoparticles and their enhanced sensor performance

    Science.gov (United States)

    Liu, Xianghong; Zhang, Jun; Guo, Xianzhi; Wu, Shihua; Wang, Shurong

    2010-03-01

    Porous α-Fe2O3 was synthesized by simple calcination of a β-FeOOH precursor derived from a facile hydrothermal method. In the hydrothermal process, only FeCl3·6H2O was used as the source material and no templates or pore-directing agents were needed. The as-prepared porous α-Fe2O3 was further employed as a support for loading Au nanoparticles (AuNPs). Due to the advantages of porous nanostructures (large surface area and facile gas diffusion) and the catalytic capability of AuNPs, the derived AuNP-supported porous α-Fe2O3 was further investigated for gas sensor applications using ethanol as a probe molecule. Obtained results showed that the AuNP-supported porous α-Fe2O3 exhibited a much higher response in comparison to pure α-Fe2O3. The enhanced sensor properties are attributed to the unique porous structures of the α-Fe2O3 support and active AuNPs for promoting sensing reactions, as well as the synergic electronic interaction between Au and α-Fe2O3. It is expected that noble metals such as Ag, Pt and Pd can also be supported on other porous metal oxide semiconductors to explore superior properties of functional nanomaterials.

  18. Control of the spatial distribution and crystal orientation of self-organized Au nanoparticles.

    Science.gov (United States)

    Yasukawa, Yukiko; Liu, Xiaoxi; Shirsath, Sagar E; Suematsu, Hisayuki; Kotaki, Yukio; Nemoto, Yoshihiro; Takeguchi, Masaki; Morisako, Akimitsu

    2016-09-23

    Ordered, two-dimensional, self-organized Au nanoparticles were fabricated using radiofrequency (RF) magnetron sputtering. The particles were uniformly spherical in shape and ultrafine in size (3-7 nm) and showed an ultrahigh density in the order of ∼10(12) inch(-2). A custom-developed sputtering apparatus that employs low sputtering power density and a minimized sputtering time (1 min) was used to markedly simplify the preparation conditions for Au nanoparticle fabrication. The spatial distribution of Au nanoparticles was rigorously controlled by placing a Ta interfacial layer between the Au nanoparticles and substrate as well as by post-annealing samples in an Ar atmosphere after the formation of Au nanoparticles. The interfacial layer and the post-annealing step caused approximately 40% of the Au nanoparticles on the substrate surface to orient in the (111) direction. This method was shown to produce ultrafine Au nanoparticles showing an ultrahigh surface density. The crystal orientation of the nanoparticles can be precisely controlled with respect to the substrate surface. Therefore, this technique promises to deliver tunable nanostructures for applications in the field of high-performance electronic devices.

  19. Des fluides au grand fleuve

    OpenAIRE

    Arrago-Boruah, Émilie

    2016-01-01

    À Guwahati, capitale de l’Assam, le fleuve Brahmapoutre s’inscrit depuis quelques décennies dans le paysage urbain comme un élément essentiellement esthétique. Avant cela, il a été le théâtre de multiples affrontements, comme avec les Moghols au xviie siècle, puis la voie d’acheminement préférée de l’East India Company pour exporter les richesses de la région jusqu’à Calcutta. Pour retracer cette évolution, la lecture d’un texte ancien en sanskrit permet d’établir une comparaison entre le fle...

  20. Developing an aqueous approach for synthesizing Au and M@Au (M = Pd, CuPt) hybrid nanostars with plasmonic properties

    Science.gov (United States)

    Du, Jingshan; Yu, Junjie; Xiong, Yalin; Lin, Zhuoqing; Zhang, Hui; Yang, Deren

    Anisotropic Au nanoparticles show unique localized surface plasmon resonance (LSPR) properties, which make it attractive in optical, sensing, and biomedical applications. In this contribution, we report a general and facile strategy towards aqueous synthesis of Au and M@Au (M = Pd, CuPt) hybrid nanostars by reducing HAuCl4 with ethanolamine in the presence of cetyltrimethylammonium bromide (CTAB). According to electron microscopic observation and spectral monitoring, we found that the layered epitaxial growth mode (i.e., Frank-van der Merwe mechanism) contributes to the enlargement of the core, while, the random attachment of Au nanoclusters onto the cores accounts for the formation of the branches. Both of them are indispensable for the formation of the nanostars. The LSPR properties of the Au nanoparticles have been well investigated with morphology control via precursor amount and growth temperature. The Au nanostars showed improved surface-enhanced Raman spectroscopy (SERS) performance for rhodamine 6G due to their sharp edges and tips, which were therefore confirmed as good SERS substrate to detect trace amount of molecules.

  1. Le confort thermique des bâtiments en région tropicale : application du modèle de Fanger au cas des laboratoires de l'université d'Abomey Calavi (Cotonou-Bénin).

    OpenAIRE

    Olissan, Aurélien; Kouchade, Clément; Andre, Philippe; Awanou, Cossi Norbert

    2013-01-01

    Fanger dans ses travaux a lié l'indice PMV, vote de confort moyen exprimé par une population d'une ambiance donnée au bilan thermique de l'individu. Ce modèle a été utilisé dans nos travaux précédents, et a permis de déterminer des conditions de confort dans la région côtière du Bénin. Le présent article a pour but de prendre en compte à travers des enquêtes, la sensation réelle thermique des occupants des ambiances étudiées pour faire une adaptation du modèle de Fanger aux conditions climati...

  2. Préparation de la Bentonite de Maghnia Intercalée au titane et/ou vanadium. Application à la réaction d’oxydation du cyclohexane

    OpenAIRE

    BELAIDI, Noureddine

    2010-01-01

    Notre travail porte sur la préparation d’une argile intercalée au titane, synthétisée par insertion dans le domaine interfoliaire des espèces cationiques obtenue par hydrolyse de Ti (OC3H7)4 avec HCl. Cette argile pontée a été ensuite pris comme support pour l’imprégnation du vanadium sous forme d’oxyde. L’analyse texturale montre que la formation des piliers d’oxyde améliore la surface spécifique. Après imprégnation par le vanadium, le volume poreux et la surface spécifique sont diminués. Ce...

  3. Rôle des matériaux-supports sur la mise en place du biofilm : application au démarrage d’un procédé de méthanisation

    OpenAIRE

    Habouzit, Frédéric

    2016-01-01

    Dans les systèmes anaérobies de traitement d'eaux usées, la biomasse microbienne complexe incluant archées et bactéries peut être maintenue au sein du procédé par l'adhésion aux supports solides sous forme de biofilm. Le but de ce travail est d'évaluer l'impact des propriétés des matériaux supports sur l’adhésion et la colonisation du consortium méthanogène. Différents matériaux (le polyéthylène, le polypropylène, le chlorure de polyvinyle, l’acrylonitrile butadiène styrène, le polycarbonate,...

  4. Gas-phase experiments on Au(III) photochemistry.

    Science.gov (United States)

    Marcum, Jesse C; Kaufman, Sydney H; Weber, J Mathias

    2011-04-14

    Irradiation of AuCl(4)(-) and AuCl(2)(OH)(2)(-) in the gas-phase using ultraviolet light (220-415 nm) leads to their dissociation. Observed fragment ions for AuCl(4)(-) are AuCl(3)(-) and AuCl(2)(-) and for AuCl(2)(OH)(2)(-) are AuCl(2)(-) and AuClOH(-). All fragment channels correspond to photoreduction of the gold atom to either Au(II) or Au(I) depending on the number of neutral ligands lost. Fragment branching ratios of AuCl(4)(-) are observed to be highly energy dependent and can be explained by comparison of the experimental data to calculated threshold energies obtained using density functional theory. The main observed spectral features are attributed to ligand-to-metal charge transfer transitions. These results are discussed in the context of the molecular-level mechanisms of Au(III) photochemistry.

  5. Magnetic depth profiling of Fe/Au multilayer using neutron ...

    Indian Academy of Sciences (India)

    Au multilayer sample for characterizing the layer structure and magnetic moment density profile. Fe/Au multilayer shows strong spin-dependent scattering at interfaces, making it a prospective GMR material. Fe/Au multilayer with bilayer ...

  6. Gd doped Au nanoclusters: Molecular magnets with novel properties

    KAUST Repository

    Mokkath, Junais Habeeb

    2014-01-01

    The structural, magnetic, and optical properties of subnanometer Au N and AuN-1Gd1 gas phase clusters (N = 2 to 8) are systematically investigated in the framework of (time-dependent) density functional theory, using the B3LYP hybrid exchange correlation functional. The size dependent evolution of the gap between the highest occupied and lowest unoccupied molecular orbitals, the magnetism, and the absorption spectra are studied. The simultaneous appearance of large magnetic moments, significant band gaps, and plasmon resonances in the visible spectral region leads to novel multi-functional nanomaterials for applications in drug delivery, magnetic resonance imaging, and photo-responsive agents. © 2013 Elsevier B.V. All rights reserved.

  7. Laser induced nanostructures created from Au layer on polyhydroxybutyrate

    Science.gov (United States)

    Michaljaničová, I.; Slepička, P.; Juřík, P.; Švorčík, V.

    2017-11-01

    Nanostructures as well as composite materials expand the range of materials properties and allow use of these materials in new and highly specific applications. In this paper, we described laser modification of polyhydroxybutyrate films covered with thin gold layer, which led to the formation of various composite structures. The crucial for the composite structures creation was setting of appropriate laser parameters; 15 mJ cm-2 laser fluence and 6 000 pulses were recognized as the best. The morphology of structures was determined by the thickness of the Au layer. The most interesting formations, very porous with the biggest roughness, were observed after treatment of foils covered with 10 nm of Au. The morphology was observed by atomic force microscopy. The influence on roughness and the difference between projected area and surface area was also determined.

  8. Imaging {Au0-PAMAM} Gold-dendrimer Nanocomposites in Cells

    International Nuclear Information System (INIS)

    Bielinska, Anna; Eichman, Jonathan D.; Lee, Inhan; Baker, James R.; Balogh, Lajos

    2002-01-01

    Dendrimer nanocomposites (DNC) are hybrid nanoparticles formed by the dispersion and immobilization of guest atoms or small clusters in dendritic polymer matrices. They have a great potential in biomedical applications due to their controlled composition, predetermined size, shape and variable surface functionalities. In this work, d=5-25 nm spherical nanoparticles composed of gold and poly(amidoamine) (PAMAM) dendrimers have been selected to demonstrate this nanoparticle based concept. {Au(0) n -PAMAM} gold dendrimer nanocomposites with a well-defined size were synthesized and imaged by transmission electron microscopy both in vitro and in vivo. DNC have also the potential to be used for imaging and drug delivery vehicles either by utilizing bioactive guests or through the incorporation of radioactive isotopes, such as Au-198

  9. A biomimetic Au@BSA-DTA nanocomposites-based contrast agent for computed tomography imaging.

    Science.gov (United States)

    Zhao, Wenjing; Wang, Zhiming; Chen, Lina; Huang, Chusen; Huang, Yuankui; Jia, Nengqin

    2017-09-01

    Early detection of cancer is increasingly important for being considered to increase the survival rate in the treatment process. The past decades years have witnessed the great progress in the biological detection application of gold nanoparticles. Herein, we reported a facile one-pot synthesis process to obtain gold nanoparticles (Au@BSA) with bovine serum albumin (BSA) as a biotemplate following with conjugation of diatrizoic acid (DTA) for a potential X-ray computed tomography (CT) imaging contrast agent (Au@BSA-DTA). The as-prepared biomimetic material was characterized systematically by several techniques. It was shown that the prepared biomaterial is colloid stable under the tested range of pH and temperature. The cell cytotoxicity assay, hemolytic assay and cell morphology observation showed that Au@BSA-DTA has good biocompatibility and hemocompatibility at a concentration of Au even up to 80μg/mL. Besides, the biomimetic material Au@BSA-DTA with double radiodense elements of Au and iodine displayed much stronger CT imaging effect compared with the traditional small molecule contrast agents, which paves the potential clinical application in cancer early diagnosis. Copyright © 2017 Elsevier B.V. All rights reserved.

  10. Cu-Au Alloys Using Monte Carlo Simulations and the BFS Method for Alloys

    Science.gov (United States)

    Bozzolo, Guillermo; Good, Brian; Ferrante, John

    1996-01-01

    Semi empirical methods have shown considerable promise in aiding in the calculation of many properties of materials. Materials used in engineering applications have defects that occur for various reasons including processing. In this work we present the first application of the BFS method for alloys to describe some aspects of microstructure due to processing for the Cu-Au system (Cu-Au, CuAu3, and Cu3Au). We use finite temperature Monte Carlo calculations, in order to show the influence of 'heat treatment' in the low-temperature phase of the alloy. Although relatively simple, it has enough features that could be used as a first test of the reliability of the technique. The main questions to be answered in this work relate to the existence of low temperature ordered structures for specific concentrations, for example, the ability to distinguish between rather similar phases for equiatomic alloys (CuAu I and CuAu II, the latter characterized by an antiphase boundary separating two identical phases).

  11. Supported Pd-Au Membrane Reactor for Hydrogen Production: Membrane Preparation, Characterization and Testing.

    Science.gov (United States)

    Iulianelli, Adolfo; Alavi, Marjan; Bagnato, Giuseppe; Liguori, Simona; Wilcox, Jennifer; Rahimpour, Mohammad Reza; Eslamlouyan, Reza; Anzelmo, Bryce; Basile, Angelo

    2016-05-09

    A supported Pd-Au (Au 7wt%) membrane was produced by electroless plating deposition. Permeation tests were performed with pure gas (H₂, H₂, N₂, CO₂, CH₄) for long time operation. After around 400 h under testing, the composite Pd-Au membrane achieved steady state condition, with an H₂/N₂ ideal selectivity of around 500 at 420 °C and 50 kPa as transmembrane pressure, remaining stable up to 1100 h under operation. Afterwards, the membrane was allocated in a membrane reactor module for methane steam reforming reaction tests. As a preliminary application, at 420 °C, 300 kPa of reaction pressure, space velocity of 4100 h(-1), 40% methane conversion and 35% hydrogen recovery were reached using a commercial Ni/Al₂O₃ catalyst. Unfortunately, a severe coke deposition affected irreversibly the composite membrane, determining the loss of the hydrogen permeation characteristics of the supported Pd-Au membrane.

  12. Origin of the p-type character of AuCl3 functionalized carbon nanotubes

    KAUST Repository

    Murat, Altynbek

    2014-02-13

    The microscopic origin of the p-type character of AuCl3 functionalized carbon nanotubes (CNTs) is investigated using first-principles self-interaction corrected density functional theory (DFT). Recent DFT calculations suggest that the p-type character of AuCl3 functionalized CNTs is due to the Cl atoms adsorbed on the CNTs. We test this hypothesis and show that adsorbed Cl atoms only lead to a p-type character for very specific concentrations and arrangements of the Cl atoms, which furthermore are not the lowest energy configurations. We therefore investigate alternative mechanisms and conclude that the p-type character is due to the adsorption of AuCl4 molecules. The unraveling of the exact nature of the p-doping adsorbates is a key step for further development of AuCl3 functionalized CNTs in water sensor applications. © 2014 American Chemical Society.

  13. Controlled Synthesis of Au@AgAu Yolk-Shell Cuboctahedra with Well-Defined Facets.

    Science.gov (United States)

    Londono-Calderon, Alejandra; Bahena, Daniel; Yacaman, Miguel J

    2016-08-02

    The synthesis of Au@AgAu yolk-shell cuboctahedra nanoparticles formed by galvanic replacement in a seed-mediated method is described. Initially, single-crystal Au seeds are used for the formation of Au@Ag core-shell nanocubes, which serve as the template material for the deposition of an external Au layer. The well-controlled synthesis yields the formation of cuboctahedra nanoparticles with smooth inner and outer Au/Ag surfaces. The deposition/oxidation process is described to understand the formation of cuboctahedra and octahedra nanoparticles. The Au core maintains the initial morphology of the seed and remains static at the center of the yolk-shell because of residual Ag. Structural analysis of the shell indicates intrinsic stacking faults (SFs) near the surface. Energy dispersive X-ray spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS) compositional analysis show an Au-Ag nonordered alloy forming the shell. The three-dimensional structure of the nanoparticles presented open facets on the [111] as observed by electron tomography SIRT reconstruction over a stack of high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) images. The geometrical model was validated by analyzing the direction of streaks in coherent nanobeam diffraction (NBD). The catalytic activity was evaluated using a model reaction based on the reduction of 4-nitrophenol (4-NTP) by NaBH4 in the presence of Au@AgAu yolk-shell nanoparticles.

  14. Synthesis of ultrathin face-centered-cubic Au@Pt and Au@Pd core-shell nanoplates from hexagonal-close-packed Au square sheets

    KAUST Repository

    Fan, Zhanxi

    2015-03-17

    The synthesis of ultrathin face-centered-cubic (fcc) Au@Pt rhombic nanoplates is reported through the epitaxial growth of Pt on hexagonal-close-packed (hcp) Au square sheets (AuSSs). The Pt-layer growth results in a hcp-to-fcc phase transformation of the AuSSs under ambient conditions. Interestingly, the obtained fcc Au@Pt rhombic nanoplates demonstrate a unique (101)f orientation with the same atomic arrangement extending from the Au core to the Pt shell. Importantly, this method can be extended to the epitaxial growth of Pd on hcp AuSSs, resulting in the unprecedented formation of fcc Au@Pd rhombic nanoplates with (101)f orientation. Additionally, a small amount of fcc (100)f-oriented Au@Pt and Au@Pd square nanoplates are obtained with the Au@Pt and Au@Pd rhombic nanoplates, respectively. We believe that these findings will shed new light on the synthesis of novel noble bimetallic nanostructures. Phase change: Ultrathin Au@Pt and Au@Pd core-shell nanoplates were prepared from Au square sheets. A phase transformation from hexagonal close-packed (hcp) to face-centered cubic (fcc) is observed upon coating the hcp Au square sheets with Pt or Pd under ambient conditions. The prepared fcc Au@Pt and Au@Pd rhombic nanoplates demonstrate unique (101)f orientation (picture shows a typical fcc Au@Pt rhombic nanoplate). © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  15. Et pourquoi pas au CERN ?

    CERN Multimedia

    Staff Association

    2015-01-01

    Télétravail ou travail à distance, aménagement des horaires de travail et autres évolutions favorables à un meilleur équilibre vie privée et vie professionnelle sont adoptés par nombre d’entreprises et d’organisations !   Rendu possible grâce au développement de nouvelles technologies dont Internet, le travail à distance séduit de plus en plus de personnels, ainsi que de plus en plus de sociétés qui y trouvent des avantages en matière de gestion de l’espace, de sécurité (moins de trajets domicile-entreprise), de développement durable (moins de pollution), de motivation et de bien-être de leurs personnels. Les horaires aménagés, voire les « core-hours1 », sont également des pratiques de plus e...

  16. A further insight into the biosorption mechanism of Au(III by infrared spectrometry

    Directory of Open Access Journals (Sweden)

    Lin Zhongyu

    2011-10-01

    Full Text Available Abstract Background The interactions of microbes with metal ions form an important basis for our study of biotechnological applications. Despite the recent progress in studying some properties of Au(III adsorption and reduction by Bacillus megatherium D01 biomass, there is still a need for additional data on the molecular mechanisms of biosorbents responsible for their interactions with Au(III to have a further insight and to make a better exposition. Results The biosorption mechanism of Au(III onto the resting cell of Bacillus megatherium D01 biomass on a molecular level has been further studied here. The infrared (IR spectroscopy on D01 biomass and that binding Au(III demonstrates that the molecular recognition of and binding to Au(III appear to occur mostly with oxygenous- and nitrogenous-active groups of polysaccharides and proteins in cell wall biopolymers, such as hydroxyl of saccharides, carboxylate anion of amino-acid residues (side-chains of polypeptide backbone, peptide bond (amide I and amide II bands, etc.; and that the active groups must serve as nucleation sites for Au(0 nuclei growth. A further investigation on the interactions of each of the soluble hydrolysates of D01, Bacillus licheniformis R08, Lactobacillus sp. strain A09 and waste Saccharomyces cerevisiae biomasses with Au(III by IR spectrometry clearly reveals an essential biomacromolecule-characteristic that seems the binding of Au(III to the oxygen of the peptide bond has caused a significant, molecular conformation-rearrangement in polypeptide backbones from β-pleated sheet to α-helices and/or β-turns of protein secondary structure; and that this changing appears to be accompanied by the occurrence, in the peptide bond, of much unbound -C=O and H-N- groups, being freed from the inter-molecular hydrogen-bonding of the β-pleated sheet and carried on the helical forms, as well as by the alternation in side chain steric positions of protein primary structure. This might

  17. Substrate effects on the analysis of biomolecular layers using Au+, Au3+ and C60+ bombardments

    International Nuclear Information System (INIS)

    Kordys, Jeanette; Fletcher, John S.; Lockyer, Nicholas P.; Vickerman, John C.

    2008-01-01

    Effects of platinum silicon, graphite and PET substrates on the secondary ion yield of sub-monolayer and multilayer samples of Cyclosporin A following 20 keV Au + , Au 3 + and C 60 + impacts have been investigated. The obtained results of sub-monolayer samples show that platinum enhances the yield of the pseudo-molecular ion following Au + and Au 3 + impacts due to the high density of the substrate that enables the energy of the primary ions to be deposited near the surface. C 60 + impacts on sub-monolayer samples are less effective, but there is an enhancement on PET substrates. Impacts of 20 keV Au + and Au 3 + are not very efficient on multilayer samples. 20 keV C 60 + impacts enhance the yields significantly, especially for the relatively high molecular weight [M+H] + ion.

  18. Study of electrical properties of Au/BN/InP MIS structures; Badanie wlasciwosci elektrycznych struktur MIS typu Au/BN/InP

    Energy Technology Data Exchange (ETDEWEB)

    Dmowski, K. [Politechnika Warszawska, Warsaw (Poland); Lepley, B.; Bath, A.; Losson, E.; Thevenin, P.; Nabil, S.A. [Metz Univ., 57 (France)

    1997-12-01

    The electrical properties of multilayer system type metal-insulator-semiconductor (MIS) have been investigated on the example of Au/BN/InP. Current-voltage as well as capacity-voltage characteristics have been measured. The applicability of such systems in microelectronics have been discussed. 7 refs, 4 figs.

  19. Exploration d’un système interfacique et de ses dynamiques : application au tourisme de réunions et de congrès

    Directory of Open Access Journals (Sweden)

    Christofle S.

    2012-10-01

    Full Text Available Le tourisme de réunions et de congrès fait se rassembler en un lieu nodal, durant au moins deux jours, des personnes issues d’horizons géographiques variés mais aux intérêts communs. Le système interfacique congressuel se structure autour de la réunion, interface immatérielle, qui prend place dans le palais des congrès, interface matérielle, et met en contact différents acteurs : congressistes, organisateurs, prestataires de services, collectivités territoriales. Ce système ouvert, localisé, s’articule autour de trois grands types d’interfaces, intra-réticulaires, inter-réseaux et réseaux-territoires dans le cadre de stratégies économiques, de destination et de développement territorial. Quatre grands effets sont induits : la diffusion et l’appropriation d’une information neuve, l’accélération de l’innovation et de l’expérimentation, la création d‘une expérience communautaire, le développement de la valeur.

  20. Amélioration de la nutrition au Cambodge au moyen de l ...

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

    Amélioration de la nutrition au Cambodge au moyen de l'aquaculture et des jardins potagers domestiques (FCRSAI). Si l'on produit au Cambodge suffisamment de riz pour nourrir la population, la sous-alimentation maternelle et infantile y demeure quand même élevée en raison de la faible diversification des cultures et du ...

  1. Prévention de la violence chez les jeunes au Guatemala, au ...

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

    Prévention de la violence chez les jeunes au Guatemala, au Honduras et au Salvador. La violence chez les jeunes, que ceux-ci en soient victimes ou responsables, est l'un des problèmes les plus importants en Amérique centrale. Ce projet de recherche servira à évaluer les stratégies actuelles de prévention de la violence ...

  2. Stability and enzyme inhibition activities of au nanoparticles using an aqueous extract of clove as a reducing and stabilizing agent

    International Nuclear Information System (INIS)

    Hameed, A.; Khan, I.; Naz, S.S.; Islam, N.U.

    2014-01-01

    Gold nanoparticles (AuNPs) were synthesized in one pot using aqueous extract of clove buds (CB) to reduce HAuCl/sub 4/ and stabilize gold in its atomic form at room temperature. To determine the potential of gold nanoparticles with clove buds (AuCB) for in vivo applications, the stability of the nanoparticles was explored as a function of temperature, pH and salt concentration. The suspensions were found to be stable for salt concentrations up to 1 mol/L, temperatures of up to 100 degree C and a pH range of 2-13. Our results indicate that CB exhibited comparable activities to standards of urease and carbonic anhydrase, but its conjugation to Au knocks out the enzyme inhibition activity by about two times. In case of xanthine oxidase activity, CB and its gold Au bio-conjugates (AuCB) are found to be absolutely inactive. (author)

  3. Rhodamine B immobilized on hollow Au-HMS material for naked-eye detection of Hg2+ in aqueous media.

    Science.gov (United States)

    Zhang, Na; Li, Gang; Cheng, Zhuhong; Zuo, Xiujin

    2012-08-30

    A simple, effective method has been demonstrated to immobilize Rhodamine B (RhB) probes on mesoporous silica (Au-HMS). The prepared chemosensor (Au-HMS-Probe) was characterized by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray powder diffraction (XRD), UV-vis spectrum and Fourier transform infrared spectroscopy (FT-IR). Further application of Au-HMS-Probe in sensing Hg(2+) was confirmed by fluorescence titration experiment. Au-HMS-Probe afforded "turn-on" fluorescence enhancement and displayed high brightness in water, and it also showed excellent selectivity for Hg(2+) over alkali (Na(+), K(+)), alkaline earth (Mg(2+), Ca(2+)) and other heavy metal ions (Ag(+), Cd(2+), Co(2+), Pb(2+), Ni(2+), Cu(2+), Fe(2+)). Importantly, Au-HMS-Probe could be regenerated by treatment with tetrapropylammonium hydroxide solution. Crown Copyright © 2012. Published by Elsevier B.V. All rights reserved.

  4. Proton channeling in Au at low energies

    International Nuclear Information System (INIS)

    Valdes, J.E.; Vargas, P.

    1996-01-01

    The electronic energy loss for low velocity protons channeled in the direction single crystal Au is calculated. The spatial distribution of valence electronic density in Au is calculated using Tight Binding Linear Muffin Tin Method. The proton trajectories are determined by numerical integration of the classical motion equation, and the energy loss is evaluated using the calculated valence electronic density in the friction term. The results allow to describe qualitatively the non linear behavior of energy loss with ion velocity observed experimentally. (author)

  5. Accidents Vasculaires Cerebraux (AVC) au Centre Hospitalier ...

    African Journals Online (AJOL)

    But: décrire les aspects épidémiologiques et évolutifs des AVC au CHU Kara. Méthodologie: Il s'est agi d'une étude prospective transversale monocentrique de cas d'AVC colligés du 1er juillet 2014 au 31 décembre 2015 dans le service de neurologie du CHU- KARA. Résultats: Cent soixante-quatre (164) patients ont ...

  6. Unravelling Thiol’s Role in Directing Asymmetric Growth of Au Nanorod–Au Nanoparticle Dimers

    KAUST Repository

    Huang, Jianfeng

    2015-12-15

    Asymmetric nanocrystals have practical significance in nanotechnologies but present fundamental synthetic challenges. Thiol ligands have proven effective in breaking the symmetric growth of metallic nanocrystals but their exact roles in the synthesis remain elusive. Here, we synthesized an unprecedented Au nanorod-Au nanoparticle (AuNR-AuNP) dimer structure with the assistance of a thiol ligand. On the basis of our experimental observations, we unraveled for the first time that the thiol could cause an inhomogeneous distribution of surface strains on the seed crystals as well as a modulated reduction rate of metal precursors, which jointly induced the asymmetric growth of monometallic dimers. © 2015 American Chemical Society.

  7. Phenomenological approach to the spin glass state of (Cu-Mn, Ag-Mn, Au-Mn and Au-Fe) alloys at low temperatures

    International Nuclear Information System (INIS)

    Al-Jalali, Muhammad A.; Kayali, Fawaz A.

    2000-01-01

    Full text.The spin glass of: (Cu-Mn, Ag-Mn, Au-Mn, Au-Fe) alloys has been extensively studied. The availability of published and assured experimental data on the susceptibility x(T) of this alloys has enabled the design and application of phenomenological approach to the spin glass state of these interesting alloys. The use of and advanced (S.P.S.S) computer software has resulted revealing some important features of the spin glass in these alloys, the most important of which is that the spin glass state do not represent as phase change

  8. Apprentissages techniques : L'apprentissage au CERN

    CERN Multimedia

    2004-01-01

    APPRENTISSAGES TECHNIQUES GESTION ET DEVELOPPEMENT DU PERSONNEL HR/PMD L'APPRENTISSAGE AU CERN pour les professions d'électronicien(ne) et de laborantin(e) en physique L'apprentissage au CERN est régi par les lois, règlements et contrats en vigueur dans le Canton de Genève. En cas de réussite à l'examen de fin d'apprentissage, les apprentis obtiennent le Certificat Fédéral de Capacité Suisse (CFC). 7 places au total sont ouvertes au recrutement pour les deux professions. L'apprentissage dure 4 ans. Minima requis pour faire acte de candidature : • avoir au moins 15 ans et moins de 21 ans à la date de début de l'apprentissage • avoir terminé la scolarité obligatoire, au minimum 9ème du Cycle d'orientation genevois (3ème en France) • être ressortissant d'un pays membre du CERN (Allemagne, Autriche, Belgiqu...

  9. A facile approach for reducing the working voltage of Au/TiO2/Au nanostructured memristors by enhancing the local electric field

    Science.gov (United States)

    Arab Bafrani, Hamidreza; Ebrahimi, Mahdi; Bagheri Shouraki, Saeed; Moshfegh, Alireza Z.

    2018-01-01

    Memristor devices have attracted tremendous interest due to different applications ranging from nonvolatile data storage to neuromorphic computing units. Exploring the role of surface roughness of the bottom electrode (BE)/active layer interface provides useful guidelines for the optimization of the memristor switching performance. This study focuses on the effect of surface roughness of the BE electrode on the switching characteristics of Au/TiO2/Au three-layer memristor devices. An optimized wet-etching treatment condition was found to modify the surface roughness of the Au BE where the measurement results indicate that the roughness of the Au BE is affected by both duration time and solution concentrations of the wet-etching process. Then we fabricated arrays of TiO2-based nanostructured memristors sandwiched between two sets of cross-bar Au electrode lines (junction area 900 μm2). The results revealed a reduction in the working voltages in current–voltage characteristic of the device performance when increasing the surface roughness at the Au(BE)/TiO2 active layer interface. The set voltage of the device (Vset) significantly decreased from 2.26–1.93 V when we increased the interface roughness from 4.2–13.1 nm. The present work provides information for better understanding the switching mechanism of titanium-dioxide-based devices, and it can be inferred that enhancing the roughness of the Au BE/TiO2 active layer interface leads to a localized non-uniform electric field distribution that plays a vital role in reducing the energy consumption of the device.

  10. Evidence for Bioavailability of Au Nanoparticles from Soil and Biodistribution within Earthworms (Eisenia fetida)

    Energy Technology Data Exchange (ETDEWEB)

    J Unrine; S Hunyadi; O Tsyusko; W Rao; A Shoults-Wilson; P Bertsch

    2011-12-31

    Because Au nanoparticles (NPs) are resistant to oxidative dissolution and are easily detected, they have been used as stable probes for the behavior of nanomaterials within biological systems. Previous studies provide somewhat limited evidence for bioavailability of Au NPs in food webs, because the spatial distribution within tissues and the speciation of Au was not determined. In this study, we provide multiple lines of evidence, including orthogonal microspectroscopic techniques, as well as evidence from biological responses, that Au NPs are bioavailable from soil to a model detritivore (Eisenia fetida). We also present limited evidence that Au NPs may cause adverse effects on earthworm reproduction. This is perhaps the first study to demonstrate that Au NPs can be taken up by detritivores from soil and distributed among tissues. We found that primary particle size (20 or 55 nm) did not consistently influence accumulated concentrations on a mass concentration basis; however, on a particle number basis the 20 nm particles were more bioavailable. Differences in bioavailability between the treatments may have been explained by aggregation behavior in pore water. The results suggest that nanoparticles present in soil from activities such as biosolids application have the potential to enter terrestrial food webs.

  11. Study of surface plasmon resonance of Au nanoparticles coated with dielectric layers

    Science.gov (United States)

    He, Jia-Yu; Huang, Chan-yan; Dai, Ning; Zhu, Da-ming

    2011-08-01

    In this work, atomic layer deposition (ALD) was used to deposit different thickness layers of Al2O3 on Au nanoparticles fabricated by thermal annealing of Au thin films. The effects of the Au-coated Al2O3 layer thickness variation to local surface plasmon resonance (LSPR) in gold (Au) nanoparticles was investigated using transmission surface plasmon resonance (T-SPR) spectroscopy. Thermal annealing of ultrathin films of Au sputtered on transparent substrates can get a dispersed metal particles system which exhibit transmission spectra showing an extinction band attributed to localized surface plasmon resonance (LSPR). The particles prepared by thermal annealing are much more like elliptical rather than sphere. The dielectric medium layer Al2O3 was deposited on these Au particles with the thickness from few nanometers to tens of nanometers by ALD. We found that All the LSPR peak positions of particles on different substrates red shifted as the thickness of deposition layer increase, but the LSPR red-shift effect of particles on alumina substrate was much more remarkable than particles on glass substrate. The results in this paper show that it is a very continent method to manipulate LSPR position which is a profound useful effect in solar cell application by controlling the deposition layer thickness on particles prepared by thermal annealing on suitable substrate.

  12. Monolayer-Enriched Production of Au-Decorated WS2 Nanosheets via Defect Engineering

    Energy Technology Data Exchange (ETDEWEB)

    Dunklin, Jeremy R [National Renewable Energy Laboratory (NREL), Golden, CO (United States); Lafargue, Paul [Ruprecht-Karls University Heidelberg; Higgins, Thomas M. [Ruprecht-Karls University Heidelberg; Forcherio, Gregory T. [U.S. Army Research Laboratory; Benamara, Mourad [University of Arkansas; McEvoy, Niall [Trinity College Dublin; Roper, D. Keith [University of Arkansas; Coleman, Jonathan N. [Trinity College Dublin; Vaynzof, Yana [Ruprecht-Karls University Heidelberg; Backes, Claudia [Ruprecht-Karls University Heidelberg

    2018-04-06

    Layered transition metal dichalcogenides (TMDs) represent a diverse, emerging source of two-dimensional (2D) nanostructures with broad application in optoelectronics and energy. Chemical functionalization has evolved into a powerful tool to tailor properties of these 2D TMDs; however, functionalization strategies have been largely limited to the metallic 1T-polytype. The work herein illustrates that 2H-semiconducting liquid-exfoliated tungsten disulfide (WS2) undergoes a spontaneous redox reaction with gold (III) chloride (AuCl3). Au nanoparticles (NPs) predominantly nucleate at nanosheet edges with tuneable NP size and density. AuCl3 is preferentially reduced on multi-layer WS2 and resulting large Au aggregates are easily separated from the colloidal dispersion by simple centrifugation. This process may be exploited to enrich the dispersions in laterally large, monolayer nanosheets. It is proposed that thiol groups at edges and defects sides reduce the AuCl3 to Au0 and are in turn oxidized to disulfides. Optical emission, i.e. photoluminescence, of the monolayers remained pristine, while the electrocatalytic activity towards the hydrogen evolution reaction is significantly improved. Taken together, these improvements in functionalization, fabrication, and catalytic activity represent an important advance in the study of these emerging 2D nanostructures.

  13. Immobilization of a human epidermal growth factor receptor 2 mimotope-derived synthetic peptide on Au and its potential application for detection of herceptin in human serum by quartz crystal microbalance.

    Science.gov (United States)

    Shang, Yuqin; Singh, Pankaj R; Chisti, Mohammad M; Mernaugh, Ray; Zeng, Xiangqun

    2011-12-01

    Therapeutic antibodies are antigenically similar to human antibodies and are difficult to detect in assays of human serum samples without the use of the therapeutic antibody's complementary antigen. Herein for the first time, we established a platform to detect Herceptin in solutions by using a small (synthetic peptide immobilized on the surface of a Au quartz electrode. We used the HER2 mimotope as a substitute for the HER2 receptor protein in piezoimmunosensor or quartz crystal microbalance (QCM) assays to detect Herceptin in human serum. We demonstrated that assay sensitivity was dependent upon the amino acids used to tether and link the peptide to the sensor surface and the buffers used to carry out the assays. The detection limit of the piezoimmunosensor assay was 0.038 nM with a linear operating range of 0.038-0.859 nM. Little nonspecific binding to other therapeutic antibodies (Avastin and Rituxan) was observed. Levels of Herceptin in serum samples obtained from treated patients, as ascertained using the synthetic peptide-based QCM assay, were typical for those treated with Herceptin. The findings of this study are significant in that low-cost synthetic peptides could be used in a QCM assay, in lieu of native or recombinant antigens or capture antibodies, to rapidly detect a therapeutic antibody in human serum. The results suggested that a synthetic peptide bearing a particular functional sequence could be applied for developing a new generation of affinity-based immunosensors to detect a broad range of clinical biomarkers.

  14. Multifunctional Fe3O4/Au core/satellite nanocubes: an efficient chemical synthesis, characterization and functionalization of streptavidin protein.

    Science.gov (United States)

    Abbas, Mohamed; RamuluTorati, Sri; Kim, CheolGi

    2017-02-14

    A novel and efficient chemical approach for the synthesis of Fe 3 O 4 /Au core/satellite nanocubes is reported. In a one-pot reaction, metallic Au nanodots were successfully deposited on the polyvinylpyrrolidone (PVP) functionalized Fe 3 O 4 nanocube surface for the fabrication of a core/satellite structure (Fe 3 O 4 /Au) by the reduction of HAuCl 4 using ammonia. Transmission electron microscopy and energy dispersive spectroscopy mapping revealed that small Au nanodots of about 2 nm average size decorated the surface of Fe 3 O 4 nanocubes. X-ray diffraction data was used to confirm the formation of both the phases of a cubic inverse spinel structure for Fe 3 O 4 and a bcc structure for Au in the core/satellite structure of Fe 3 O 4 /Au nanocubes. The magnetic properties of the seed Fe 3 O 4 nanocubes and Fe 3 O 4 /Au core/satellite nanocubes were measured by using a superconducting quantum interference device at 300 K. For biological application purposes, the as-synthesized Fe 3 O 4 /Au core/satellite nanocubes were functionalized by cysteamine followed by successful immobilization of streptavidin protein as confirmed through the fluorescence confocal microscopy images.

  15. One-step synthesis of PtPdAu ternary alloy nanoparticles on graphene with superior methanol electrooxidation activity

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Yuzhen; Gu Yonge; Lin Shaoxiong; Wei Jinping; Wang Zaihua [Department of Chemistry, Lanzhou University, Lanzhou 730000 (China); Wang Chunming, E-mail: wangcm@lzu.edu.cn [Department of Chemistry, Lanzhou University, Lanzhou 730000 (China); Du Yongling; Ye Weichun [Department of Chemistry, Lanzhou University, Lanzhou 730000 (China)

    2011-10-01

    Highlights: > PtPdAu nanoparticles were synthesized on graphene sheets via chemical reduction method. > The prepared PtPdAu nanoparticles were ternary alloy with fcc structure. > The catalyst exhibited superior catalytic activity and stability for MOR in alkaline. - Abstract: Well-dispersed PtPdAu ternary alloy nanoparticles were synthesized on graphene sheets via a simple one-step chemical reduction method in ethylene glycol (EG) and water system, in which EG served as both reductive and dispersing agent. The electrocatalytic activity of PtPdAu/G was tested by methanol oxidation reaction (MOR). The catalyst was further characterized by transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDX), X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD), which indicated that the as-synthesized PtPdAu nanoparticles with alloy structures were successfully dispersed on the graphene sheets. Electrocatalytic properties of the catalyst for MOR in alkaline have been investigated by cyclic voltammetry (CV), chronoamperometry and Tafel curves. The electrocatalytic activity and stability of PtPdAu/G were superior to PtPd/G, PtAu/G and Pt/G. In addition, the anodic peak current on PtPdAu/G catalyst was proportional to the concentration of methanol in the range of 0.05-1.00 M. This study implies that the prepared catalyst have great potential applications in fuel cells.

  16. Au@TiO2 yolk-shell nanostructures for enhanced performance in both photoelectric and photocatalytic solar conversion

    Science.gov (United States)

    He, Qinrong; Sun, Hang; Shang, Yinxing; Tang, Yanan; She, Ping; Zeng, Shan; Xu, Kongliang; Lu, Guolong; Liang, Song; Yin, Shengyan; Liu, Zhenning

    2018-05-01

    Solar energy conversion is an important field gaining increasing interest. Herein, bio-inspired Au@TiO2 yolk-shell nanoparticles (NPs) have been prepared via a facial one-pot hydrothermal approach. The Au@TiO2 yolk-shell NPs can self-assemble into 3D-structure to form photoelectrode for photoelectric conversion. The obtained photoelectrode demonstrates a swift and stable photocurrent of 3.5 μA/cm2, which is 4.2 and 1.6 times higher than those of the photocurrents generated by the counterparts of commercial TiO2 and Au@TiO2 core-shell NPs, respectively. Moreover, compared to the commercial TiO2 and Au@TiO2 core-shell NPs, the Au@TiO2 yolk-shell NPs also exhibit superior photocatalytic activity, delivering a H2 evolution rate of 4.92 mmol/g h. The performance improvement observed for the Au@TiO2 yolk-shell NPs is likely contributed by two synergistic factors, i.e. the incorporation of AuNPs and the unique hollow structure, which benefit the activity by simultaneously enhancing light utilization, charge separation and reaction site accessibility. The rational design and fabrication of Au@TiO2 yolk-shell NPs hold great promise for future application in efficient solar energy conversion.

  17. Long-term antibacterial characteristics and cytocompatibility of titania nanotubes loaded with Au nanoparticles without photocatalytic effects

    Energy Technology Data Exchange (ETDEWEB)

    Wang, Guomin [Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong (China); Feng, Hongqing, E-mail: fenghongqing@binn.cas.cn [Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong (China); Beijing Institute of Nanoenergy and Nanosystems, Chinese Academy of Sciences, National Center for Nanoscience and Technology (NCNST), Beijing 100083 (China); Jin, Weihong; Gao, Ang; Peng, Xiang; Li, Wan; Wu, Hao [Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong (China); Li, Zhou [Beijing Institute of Nanoenergy and Nanosystems, Chinese Academy of Sciences, National Center for Nanoscience and Technology (NCNST), Beijing 100083 (China); Chu, Paul K., E-mail: paul.chu@cityu.edu.hk [Department of Physics and Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong (China)

    2017-08-31

    Highlights: • Au@TiO{sub 2}-NT shows long-term antibacterial effects without photocatalytical effects. • An ROS-free antibacterial process is confirmed. • Au@TiO{sub 2}-NT shows good compatibility with osteoblasts and does not induce ROS production. - Abstract: Au nanoparticles (NPs) can endow titania nanotubes (Au@TiO{sub 2}-NT) with light-independent antibacterial properties which bode well for in vivo application because of the dark environment inside tissues. In this work, the long-term antibacterial bactericidal properties and cytocompatibility of Au@TiO{sub 2}-NT without photocatalytic effects are studied in details. The materials exhibit antibacterial effects against Staphylococcus aureus according to antibacterial tests carried out for a total time of 21 days, which are normally long enough for early stage tissue healing after surgery. In addition, adhesion and proliferation of MC3T3-E1 osteoblasts on Au@TiO{sub 2}-NT reveal cytocompatibility comparable to that of TiO{sub 2}-NT. No reactive oxygen species (ROS) are detected from either the bacteria or MC3T3-E1 cells cultured on the Au@TiO{sub 2}-NT surface. The absence of ROS, long-term antibacterial properties, and cytocompatibility make Au@TiO{sub 2}-NT promising biomaterials in orthopedic devices and implants.

  18. A grain boundary phase transition in Si–Au

    International Nuclear Information System (INIS)

    Ma, Shuailei; Meshinchi Asl, Kaveh; Tansarawiput, Chookiat; Cantwell, Patrick R.; Qi, Minghao; Harmer, Martin P.; Luo, Jian

    2012-01-01

    A grain boundary transition from a bilayer to an intrinsic (nominally clean) boundary is observed in Si–Au. An atomically abrupt transition between the two complexions (grain boundary stabilized phases) implies the occurrence of a first-order interfacial phase transition associated with a discontinuity in the interfacial excess. This observation supports a grain-boundary complexion theory with broad applications. This transition is atypical in that the monolayer complexion is absent. A model is proposed to explain the bilayer stabilization and the origin of this complexion transition.

  19. Models for the Behavior of Offshore Structure Foundations. Part Two: Applications to Structural Design and Quality Assurance Processes Modèles pour le comportement des fondations d'ouvrages types marins. Deuxième partie : applications au calcul d'ouvrage et processus d'assurance qualité

    Directory of Open Access Journals (Sweden)

    Meimon Y.

    2006-11-01

    structure. Prospects opened up by the research are discussed. La conception des fondations de grands ouvrages est une tâche complexe qui requiert à la fois l'expérience de l'expert et l'utilisation de modèles numériques adéquats pour assurer la sécurité et optimiser les coûts de dimensionnement. En fait, prévoir le comportement d'une fondation nécessite de bien évaluer les effets combinés de la technique de mise en place, de la variabilité spatiale des propriétés mécaniques, de l'incertitude sur les chargements et des techniques de modélisation du comportement mécanique des géomatériaux. Ceci est particulièrement vrai pour les plates-formes marines, qu'elles soient destinées à l'exploration ou à la production du pétrole, dans la mesure où les chargements non-monotones dus à l'environnement marin, souvent très sévère, peuvent avoir des effets très néfastes sur le comportement de ces structures. On présente, en deux parties, la synthèse d'une dizaine d'années d'activités de recherche, menées par une équipe de l'Institut Français du Pétrole (IFP, en collaboration avec plusieurs équipes universitaires et des centres techniques et industriels, pour la mise au point de méthodologies et d'outils adaptés au calcul du comportement des fondations d'ouvrages types marins durant toute la durée de vie de la plate-forme. Cet article concerne la deuxième partie qui est dévolue à l'application des modèles développés au calcul d'ouvrage par la méthode des éléments finis et à l'exposé d'un processus de validation des modèles, étape d'une démarche d'assurance qualité. Méthodes pour le calcul des fondations marines : Le système de programmes FONDOF utilisant la méthode des éléments finis a été développé. Il comprend (fig. 1. 1 des interfaces interactives de mise en données et de dépouillement des résultats ainsi que des modules de calcul, opérationnels comme FONGEO pour les calculs bi et tridimensionnels ou FONDAX pour le

  20. 100-MeV proton beam intensity measurement by Au activation analysis using {sup 197}Au(p, pn){sup 196}Au and {sup 197}Au(p, p3n){sup 194}Au reactions

    Energy Technology Data Exchange (ETDEWEB)

    Mokhtari Oranj, Leila [Division of Advanced Nuclear Engineering, POSTECH, Pohang 37673 (Korea, Republic of); Jung, Nam-Suk; Oh, Joo-Hee [Pohang Accelerator Laboratory, POSTECH, Pohang 37673 (Korea, Republic of); Lee, Hee-Seock, E-mail: lee@postech.ac.kr [Pohang Accelerator Laboratory, POSTECH, Pohang 37673 (Korea, Republic of)

    2016-05-15

    The proton beam intensity of a 100-MeV proton linac at the Korea Multi-purpose Accelerator Complex (KOMAC) was measured by an Au activation analysis using {sup 197}Au(p, pn){sup 196}Au and {sup 197}Au(p, p3n){sup 194}Au reactions to determine the accuracy and precision of beam intensity measurement using Gafchromic film dosimetry method. The target, irradiated by 100-MeV protons, was arranged in a stack consisting of Au, Al foils and Pb plates. The yields of produced radio-nuclei in Au foils were obtained by gamma-ray spectroscopy. The FLUKA code was employed to calculate the energy spectrum of protons onto the front surface of Au foils located at three different depth points of the target and also to investigate the condition of incident beam on the target. A good agreement was found between the beam intensity measurements using the activation analysis method at three different depth points of the target. An excellent agreement was also observed between the beam intensity measurements using the Au activation analysis method and the dosimetry method using Gafchromic film.

  1. Effect of Au Precursor and Support on the Catalytic Activity of the Nano-Au-Catalysts for Propane Complete Oxidation

    Directory of Open Access Journals (Sweden)

    Arshid M. Ali

    2015-01-01

    Full Text Available Catalytic activity of nano-Au-catalyst(s for the complete propane oxidation was investigated. The results showed that the nature of both Au precursor and support strongly influences catalytic activity of the Au-catalyst(s for the propane oxidation. Oxidation state, size, and dispersion of Au nanoparticles in the Au-catalysts, surface area, crystallinity, phase structure, and redox property of the support are the key aspects for the complete propane oxidation. Among the studied Au-catalysts, the AuHAuCl4-Ce catalyst is found to be the most active catalyst.

  2. High hardness in the biocompatible intermetallic compound β-Ti3Au.

    Science.gov (United States)

    Svanidze, Eteri; Besara, Tiglet; Ozaydin, M Fevsi; Tiwary, Chandra Sekhar; Wang, Jiakui K; Radhakrishnan, Sruthi; Mani, Sendurai; Xin, Yan; Han, Ke; Liang, Hong; Siegrist, Theo; Ajayan, Pulickel M; Morosan, E

    2016-07-01

    The search for new hard materials is often challenging, but strongly motivated by the vast application potential such materials hold. Ti3Au exhibits high hardness values (about four times those of pure Ti and most steel alloys), reduced coefficient of friction and wear rates, and biocompatibility, all of which are optimal traits for orthopedic, dental, and prosthetic applications. In addition, the ability of this compound to adhere to ceramic parts can reduce both the weight and the cost of medical components. The fourfold increase in the hardness of Ti3Au compared to other Ti-Au alloys and compounds can be attributed to the elevated valence electron density, the reduced bond length, and the pseudogap formation. Understanding the origin of hardness in this intermetallic compound provides an avenue toward designing superior biocompatible, hard materials.

  3. Toward hybrid Au nanorods @ M (Au, Ag, Pd and Pt) core-shell heterostructures for ultrasensitive SERS probes

    Science.gov (United States)

    Xie, Xiaobin; Gao, Guanhui; Kang, Shendong; Lei, Yanhua; Pan, Zhengyin; Shibayama, Tamaki; Cai, Lintao

    2017-06-01

    Being able to precisely control the morphologies of noble metallic nanostructures is of essential significance for promoting the surface-enhanced Raman scattering (SERS) effect. Herein, we demonstrate an overgrowth strategy for synthesizing Au @ M (M = Au, Ag, Pd, Pt) core-shell heterogeneous nanocrystals with an orientated structural evolution and highly improved properties by using Au nanorods as seeds. With the same reaction condition system applied, we obtain four well-designed heterostructures with diverse shapes, including Au concave nanocuboids (Au CNs), Au @ Ag crystalizing face central cube nanopeanuts, Au @ Pd porous nanocuboids and Au @ Pt nanotrepangs. Subsequently, the exact overgrowth mechanism of the above heterostructural building blocks is further analysed via the systematic optimiziation of a series of fabrications. Remarkably, the well-defined Au CNs and Au @ Ag nanopeanuts both exhibit highly promoted SERS activity. We expect to be able to supply a facile strategy for the fabrication of multimetallic heterogeneous nanostructures, exploring the high SERS effect and catalytic activities.

  4. Optimization of nanocomposite Au/TiO2 thin films towards LSPR optical-sensing

    Science.gov (United States)

    Rodrigues, M. S.; Costa, D.; Domingues, R. P.; Apreutesei, M.; Pedrosa, P.; Martin, N.; Correlo, V. M.; Reis, R. L.; Alves, E.; Barradas, N. P.; Sampaio, P.; Borges, J.; Vaz, F.

    2018-04-01

    Nanomaterials based on Localized Surface Plasmon Resonance (LSPR) phenomena are revealing to be an important solution for several applications, namely those of optical biosensing. The main reasons are mostly related to their high sensitivity, with label-free detection, and to the simplified optical systems that can be implemented. For the present work, the optical sensing capabilities were tailored by optimizing LSPR absorption bands of nanocomposite Au/TiO2 thin films. These were grown by reactive DC magnetron sputtering. The main deposition parameters changed were the number of Au pellets placed in the Ti target, the deposition time, and DC current applied to the Ti-Au target. Furthermore, the Au NPs clustering, a key feature to have biosensing responses, was induced by several post-deposition in-air annealing treatments at different temperatures, and investigated via SEM analysis. Results showed that the Au/TiO2 thin films with a relatively low thickness (∼100 nm), revealing concentrations of Au close to 13 at.%, and annealed at temperatures above 600 °C, had the most well-defined LSPR absorption band and thus, the most promising characteristics to be explored as optical sensors. The NPs formation studies revealed an incomplete aggregation at 300 and 500 ⁰C and well-defined spheroidal NPs for higher temperatures. Plasma treatment with Ar led to a gradual blue-shift of the LSPR absorption band, which demonstrates the sensitivity of the films to changes in the dielectric environment surrounding the NPs (essential for optical sensing applications) and the exposure of the Au nanoparticles (crucial for a higher sensitivity).

  5. Multistep production of eta and hard pi(0) mesons in subthreshold Au-Au collisions

    NARCIS (Netherlands)

    Appenheimer, M; Averbeck, R; Charbonnier, Y; Diaz, J; Doppenschmidt, A; Hejny, [No Value; Hlavac, S; Holzmann, R; Kugler, A; Lohner, H; Marin, A; Metag, [No Value; Novotny, R; Ostendorf, RW; Pleskac, R; Schubert, A; Schutz, Y; Simon, RS; Stratmann, R; Stroher, H; Tlusty, P; Vogt, PH; Wagner, [No Value; Weiss, J; Wilschut, HW; Wissmann, F; Wolf, M

    1998-01-01

    The neutral pi(o) and eta mesons are studied in Au-197-Au-197 collisions at an incident energy of 800A MeV, substantially below the threshold for eta production in N-N collisions. While the gross pi(o) multiplicity increases almost linearly with the number of participant nucleons, the multiplicities

  6. Stability of gold cages (Au16 and Au17) at finite temperature

    Indian Academy of Sciences (India)

    the pyramid. Both the clusters melt around 780 K, a temperature much below the bulk melting temperature. However, Au19 undergoes a vacancy-assisted melting transition leading to a broad peak in the heat capacity curve whereas Au20 with a symmetric ground state has a well-defined peak in the heat capacity curve. 846.

  7. Charged particle density distributions in Au·Au collisions at ...

    Indian Academy of Sciences (India)

    Charged particle pseudorapidity distributions have been measured in Au·Au collisions using the BRAHMS ... Relativistic heavy-ion collisions; charged hadron production; pseudorapidity distribu- tions; centrality .... the predictions of two different theoretical models: (i) the high density gluon saturation model of Kharzeev and ...

  8. Stability of gold cages (Au16 and Au17) at finite temperature

    Indian Academy of Sciences (India)

    2015-11-27

    Nov 27, 2015 ... We have employed ab initio molecular dynamics to investigate the stability of the smallest gold cages, namely Au16 and Au17, at finite temperatures. First, we obtain the ground state structure along with at least 50 distinct isomers for both the clusters. This is followed by the finite temperature simulations of ...

  9. Charged particle density distributions in Au·Au collisions at ...

    Indian Academy of Sciences (India)

    FOUAD RAMI, for the BRAHMS Collaboration. Institut de Recherches Subatomiques, IN2P3-CNRS, Université Louis Pasteur, Strasbourg, France. Abstract. Charged particle pseudorapidity distributions have been measured in Au·Au collisions using the BRAHMS detector at RHIC. The results are presented as a function of ...

  10. Thermodynamic Measurements on Alloys and Compounds in Ag-Au-Se and Ag-Pd systems by the Electromotive Force Method

    OpenAIRE

    Feng, Dawei

    2014-01-01

    Gold and silver chalcogenides are significant minerals and major carriers of precious metals, and silver palladium alloy is one of the most important silver alloys with various industrial applications. The Ag-Au-Se ternary system and the Ag-Pd binary system have been investigated by the electromotive force (EMF) method in this study. For the Ag-Au-Se ternary system, the numerical values of the standard thermodynamic functions of the compounds Ag2Se (naumannite), AuSe, and Ag3AuSe2 (fisches...

  11. Influence of Au Nanoparticle Shape on Au@Cu2O Heterostructures

    Directory of Open Access Journals (Sweden)

    Jie Zhu

    2015-01-01

    Full Text Available Synthesis of metal-semiconductor heterostructures may allow the combination of function of the corresponding components and/or the enhanced performance resulting from the interactions between all the components. In this paper, Au@Cu2O core-shell heterostructures are prepared by a seed-growth method, using different-shaped Au nanocrystals as the seeds such as nanorods, octahedra, decahedra, dots, and nanocubes. The results revealed that the final structure of Au@Cu2O was greatly influenced by the shape of the seeds used. Exposure of Cu2O{111} and Cu2O{001} favored when the overgrowth happened on Au{111} and Au{001} surface, respectively. The size of the product can also be tuned by the amount of the seeds. The results reported here provide a thinking clue to modulate the shape and size of core-shell nanocrystals, which is useful in developing new materials with desired performance.

  12. L'impact d'un Système Public d'Information sur l'intégration et l'efficacité des marchés : une application du modèle "Parity Bounds" au cas du maïs au Bénin

    Directory of Open Access Journals (Sweden)

    Kpenavoun Chogou, S.

    2013-01-01

    Full Text Available Measuring the impact of Public Market Information Systems on market integration and efficiency: an application of the Parity Bounds Model in maize markets in Benin. During the 1990s, agricultural market reforms prevailed within the economic liberalization undertaken in many sub-Saharan countries. In these countries, government intervention in the commodity markets through marketing boards or parastatal organizations was abandoned in favor of new market reforms. Public Market Information Systems (PMIS thus emerged as part of these reforms. Even though great positive impacts were expected from these reforms, little empirical work has been carried out to evaluate their effects. This article investigates how PMIS has affected the market performance of maize, a major staple food crop in Benin. We use a modified version of the Parity Bounds Model (PBM. This method allows the estimation of the rates of spatial market efficiency or integration, but also the estimation of the rates of market arbitrage, autarky, profitable opportunities and the violation of market arbitrage conditions. Results showed that Benin's agricultural sector suffered from a lack of quality training in how to follow the government-supported market information system implemented in the early 1990s. Subsequently, PMIS did not significantly improve the degree of market integration, although the reforms did induce new marketing opportunities. Results also showed that the impact of PMIS is limited by other market imperfections, such as entry barriers for non-residents or for persons not in local informal trade organizations, and the non-transparent enforcement of formal regulations. This study therefore recommends the implementation of more efficiency-raising policies in order to encourage competition and to allow PMIS to fulfill the expectations of farmers and consumers. Improving food producers and traders' access to reliable information will allow them to better exploit the market

  13. Excitation functions for 197Au (d, p)198Au, 197Au(d, 2n)197mHg, 197Au(d, 2n)197Hg and 197Au(d, p2n)196Au

    International Nuclear Information System (INIS)

    Long Xianguan; Peng Xiufeng; He Fuqing

    1987-01-01

    By using activation method and stack-foil technique, the excitation functions for d + 197 Au reaction in 6.6-13.1 MeV energy range are measured. The measured values are compared with previous results and theoretical calculations

  14. Surface plasmon resonance-induced photocatalysis by Au nanoparticles decorated mesoporous g-C{sub 3}N{sub 4} nanosheets under direct sunlight irradiation

    Energy Technology Data Exchange (ETDEWEB)

    Tonda, Surendar; Kumar, Santosh; Shanker, Vishnu, E-mail: vishnu@nitw.ac.in

    2016-03-15

    Highlights: • The Au/mp-g-C{sub 3}N{sub 4} was synthesized via a template-free and green in situ strategy. • Au/mp-g-C{sub 3}N{sub 4} nanosheets possesses high surface area and porous structure. • Au/mp-g-C{sub 3}N{sub 4} showed dramatic photocurrent response and photocatalytic activity. • The high performance is due to SPR of Au and mesoporous structure. • Au/mp-g-C{sub 3}N{sub 4} nanosheets exhibited high photostability. - Abstract: In recent years, surface plasmon-induced photocatalytic materials with tunable mesoporous framework have attracted considerable attention in energy conversion and environmental remediation. Herein we report a novel Au nanoparticles decorated mesoporous graphitic carbon nitride (Au/mp-g-C{sub 3}N{sub 4}) nanosheets via a template-free and green in situ photo-reduction method. The synthesized Au/mp-g-C{sub 3}N{sub 4} nanosheets exhibit a strong absorption edge in visible and near-IR region owing to the surface plasmon resonance effect of Au nanoparticles. More attractively, Au/mp-g-C{sub 3}N{sub 4} exhibited much higher photocatalytic activity than that of pure mesoporous and bulk g-C{sub 3}N{sub 4} for the degradation of rhodamine B under sunlight irradiation. Furthermore, the photocurrent and photoluminescence studies demonstrated that the deposition of Au nanoparticles on the surface of mesoporous g-C{sub 3}N{sub 4} could effectively inhibit the recombination of photogenerated charge carriers leading to the enhanced photocatalytic activity. More importantly, the synthesized Au/mp-g-C{sub 3}N{sub 4} nanosheets possess high reusability. Hence, Au/mp-g-C{sub 3}N{sub 4} could be promising photoactive material for energy and environmental applications.

  15. Simulation numérique des transferts thermiques dans un système de séchage solaire du bois

    OpenAIRE

    Khouya , Ahmed; Benabdelouhab , Jaâfar; Draoui , Abdeslam

    2007-01-01

    International audience; Les auteurs présentent une étude théorique sur un système de séchage constitué d'un capteur solaire à air de type multi–passes muni d'ailettes et couplé à une cuve de stockage dans les conditions climatiques de la région de Tanger au Maroc. L'étude est réalisée à partir des modèles mathématiques obtenus par l'écriture des lois de conservation de l'énergie dans les différentes composantes du système. Des simulations ont été réalisées en exploitant des mesures expériment...

  16. Synthesis and characterization in AuCu–Si nanostructures

    Energy Technology Data Exchange (ETDEWEB)

    Novelo, T.E., E-mail: tenovelo@hotmail.com [Centro de Investigación en Materiales Avanzados, S.C., Laboratorio Nacional de Nanotecnología, Av. Miguel de Cervantes 120, Complejo Industrial Chihuahua, 31109 Chihuahua, Chihuahua Mexico (Mexico); Amézaga-Madrid, P. [Centro de Investigación en Materiales Avanzados, S.C., Laboratorio Nacional de Nanotecnología, Av. Miguel de Cervantes 120, Complejo Industrial Chihuahua, 31109 Chihuahua, Chihuahua Mexico (Mexico); Maldonado, R.D. [Universidad Anáhuac-Mayab, Carretera Mérida-Progreso Km. 15.5 A.P. 96-Cordemex, CP. 97310 Mérida, Yucatán Mexico (Mexico); Oliva, A.I. [Centro de Investigación y de Estudios Avanzados el IPN Unidad Mérida, Departamento de Física Aplicada, Km 6 Antigua Carretera a Progreso, A.P. 73-Cordemex, 97310 Mérida, Yucatán Mexico (Mexico); Alonzo-Medina, G.M. [Universidad Anáhuac-Mayab, Carretera Mérida-Progreso Km. 15.5 A.P. 96-Cordemex, CP. 97310 Mérida, Yucatán Mexico (Mexico)

    2015-03-15

    Au/Cu bilayers with different Au:Cu concentrations (25:75, 50:50 and 75:25 at.%) were deposited on Si(100) substrates by thermal evaporation. The thicknesses of all Au/Cu bilayers were 150 nm. The alloys were prepared by thermal diffusion into a vacuum oven with argon atmosphere at 690 K during 1 h. X-ray diffraction analysis revealed different phases of AuCu and CuSi alloys in the samples after annealing process. CuSi alloys were mainly obtained for 25:75 at.% samples, meanwhile the AuCuII phase dominates for samples prepared with 50:50 at.%. Additionally, the Au:Cu alloys with 75:25 at.%, produce Au{sub 2}Cu{sub 3} and Au{sub 3}Cu phases. The formed alloys were characterized by scanning electron microscopy (SEM), atomic force microscopy (AFM), transmission electron microscopy (TEM) and energy dispersive spectroscopy (EDS) to study the morphology and the elemental concentration of the formed alloys. - Highlights: • AuCu/Si alloy thin films were prepared by thermal diffusion. • Alloys prepared with 50 at.% of Au produce the AuCuII phase. • Alloys prepared with 75 at.% of Au produce Au{sub 3}Cu and Au{sub 2}Cu{sub 3} phases. • All alloys present diffusion of Si and Cu through the CuSi alloy formation.

  17. Synthesis and characterization in AuCu–Si nanostructures

    International Nuclear Information System (INIS)

    Novelo, T.E.; Amézaga-Madrid, P.; Maldonado, R.D.; Oliva, A.I.; Alonzo-Medina, G.M.

    2015-01-01

    Au/Cu bilayers with different Au:Cu concentrations (25:75, 50:50 and 75:25 at.%) were deposited on Si(100) substrates by thermal evaporation. The thicknesses of all Au/Cu bilayers were 150 nm. The alloys were prepared by thermal diffusion into a vacuum oven with argon atmosphere at 690 K during 1 h. X-ray diffraction analysis revealed different phases of AuCu and CuSi alloys in the samples after annealing process. CuSi alloys were mainly obtained for 25:75 at.% samples, meanwhile the AuCuII phase dominates for samples prepared with 50:50 at.%. Additionally, the Au:Cu alloys with 75:25 at.%, produce Au 2 Cu 3 and Au 3 Cu phases. The formed alloys were characterized by scanning electron microscopy (SEM), atomic force microscopy (AFM), transmission electron microscopy (TEM) and energy dispersive spectroscopy (EDS) to study the morphology and the elemental concentration of the formed alloys. - Highlights: • AuCu/Si alloy thin films were prepared by thermal diffusion. • Alloys prepared with 50 at.% of Au produce the AuCuII phase. • Alloys prepared with 75 at.% of Au produce Au 3 Cu and Au 2 Cu 3 phases. • All alloys present diffusion of Si and Cu through the CuSi alloy formation

  18. Au nanoparticles films used in biological sensing

    Energy Technology Data Exchange (ETDEWEB)

    Rosales Perez, M; Delgado Macuil, R; Rojas Lopez, M; Gayou, V L [Centro de Investigacion en BiotecnologIa Aplicada del IPN, Tepetitla Tlaxcala Mexico C.P. 90700 (Mexico); Sanchez Ramirez, J F, E-mail: mrosalespe@ipn.m [CICATA Legaria Instituto Politecnico Nacional, Mexico Distrito Federal (Mexico)

    2009-05-01

    Lactobacillus para paracasei are used commonly as functional food and probiotic substances. In this work Au nanoparticles self-assembled films were used for Lactobacillus para paracasei determination at five different concentrations. Functionalized substrates were immersed in a colloidal solution for one and a half hour at room temperature and dried at room temperature during four hours. After that, drops of Lactobacillus para paracasei in aqueous solution were put into the Au nanoparticles film and let dry at room temperature for another two hours. Infrared spectroscopy in attenuated total reflectance sampling mode was used to observe generation peaks due to substrate silanization, enhancement of Si-O band intensity due to the Au colloids added to silanized substrate and also to observe the enhancement of Lactobacillus para paracasei infrared intensity of the characteristic frequencies at 1650, 1534 and 1450 cm{sup -1} due to surface enhancement infrared absorption.

  19. Green synthesis of noble nanometals (Au, Pt, Pd) using glycerol under microwave irradiation conditions

    Science.gov (United States)

    A newer application of glycerol in the field of nanomaterials synthesis has been developed from both the economic and environmental points of view. Glycerol can act as a reducing agent for the fabrication of noble nanometals, such as Au, Pt, and Pd, under microwave irradiation. T...

  20. Antiproton distributions in Au+nucleus collisions

    Energy Technology Data Exchange (ETDEWEB)

    Beavis, D.; Debbe, R. [Brookhaven National Laboratory, Upton, New York (United States); Bennett, M.J.; Chikanian, A.; Kumar, B.S.; Nagle, J.L.; Pope, J.K. [Yale University, A.W. Wright Nuclear Structure Laboratory, New Haven, Connecticut (United States); Carroll, J.B.; Hallman, T.J. [University of California at Los Angeles, Los Angeles, California (United States); Chiba, J.; Tanaka, K.H. [National Laboratory for High Energy Physics (KEK), Tsukuba (Japan); Crawford, H.J.; Cronqvist, M.; Dardenne, Y.; Engelage, J.; Greiner, L.; Kuo, C. [University of California Space Sciences Laboratory, Berkeley, California (United States); Doke, T.; Kashiwagi, T.; Kikuchi, J. [Waseda University, Tokyo (Japan); Hayano, R.S. [University of Tokyo, Tokyo (Japan); Heckman, H.H.; Lindstrom, P.J. [Lawrence Berkeley Laboratory, Berkeley, California (United States); Mitchell, J.W. [Universities Space Sciences Research Association/Goddard Space Flight Center, Greenbelt, Maryland (United States); Nagamiya, S.; Stankus, P.; Zhan, W. [Nevis Laboratory, Columbia University, Irvington, New York (United States); Welsh, R.C. [Johns Hopkins University, Baltimore, Maryland (United States)

    1997-09-01

    Experiment E878 at the BNL-AGS has measured the invariant cross sections of antiprotons produced near p{sub t}=0 in interactions of 10.8 GeV/c Au beams with targets of Al, Cu, and Au. The data were measured for a wide range of centralities and rapidities using a focusing beamline spectrometer and a high-rate centrality detector. We compare our data with the predictions of simple models and sophisticated transport models to explore the physics of antiproton production and annihilation. {copyright} {ital 1997} {ital The American Physical Society}

  1. Total structure determination of thiolate-protected Au38 nanoparticles.

    Science.gov (United States)

    Qian, Huifeng; Eckenhoff, William T; Zhu, Yan; Pintauer, Tomislav; Jin, Rongchao

    2010-06-23

    We report the total structure of Au(38)(SC(2)H(4)Ph)(24) nanoparticles determined by single crystal X-ray crystallography. This nanoparticle is based upon a face-fused Au(23) biicosahedral core, which is further capped by three monomeric Au(SR)(2) staples at the waist of the Au(23) rod and six dimeric staples with three on the top icosahedron and other three on the bottom icosahedron. The six Au(2)(SR)(3) staples are arranged in a staggered configuration, and the Au(38)S(24) framework has a C(3) rotation axis.

  2. Statistical interpretation of uncertainty coefficients in thermal calculations for nuclear reactors. Particular problems in the application of the sigma method. Application to redistribution of the flow; Interpretation statistique des coefficients d'incertitude dans le calcul thermique des reacteurs nucleaires. Problemes particuliers d'application de la methode des {delta}. Application au calcul de la redistribution de debit

    Energy Technology Data Exchange (ETDEWEB)

    Fabrega, S. [Commissariat a l' Energie Atomique, Grenoble (France). Centre d' Etudes Nucleaires

    1970-07-01

    This report begins with a presentation of various statistical methods which make it possible to take into account the uncertainties involved in thermal calculations for nuclear reactors. The use of the variance addition theorem ({sigma} method) for calculating the probability of a thermal accident in a reactor is now very common. This method has still certain fundamental problems however (correlation between the variables, non-linearity) which results in it being abandoned in favour of less elegant methods, which are also less rigorous, e.g. the Monte Carlo method. We have attempted to show in this work how it is possible to generalize the {sigma} method to take into account the difficulties which limits its use. The great advantage of the {sigma} method is that it is relatively fast to apply and is also analytical. It enables one to understand the intricacies of the phenomena and the influence of various conditions which can be imposed in the construction of a reactor. The last part of this work is dedicated to an application of the 3-{sigma} method to the calculation of the safety margin in the case of the phenomenon of flow redistribution. Numerical results are given for the case of a high flux reactor. They show that the improvement in the performance due to the use of the statistical method is quite substantial ; whereas the sum of the uncertainties means that the maximum available power (which would be obtained if there were no uncertainty) should be divided by 1.6 approximately, this power should be divided by 1.25 if the average accident frequency is assumed to be 1 in a thousand. The accident frequency decreases very rapidly if the power is still further diminished; a division by 1.33 lowers the frequency to about 1 in 10,000. It thus appears than in practice the statistical method leads to a decrease by a factor of at least 2 in the loss of performance due to the uncertainties.

  3. On the Stark broadening in the Au I and Au II spectra from a helium plasma

    Science.gov (United States)

    Djeniže, S.

    2009-03-01

    The Stark FWHM (Full-Width at Half of the Maximal line intensity, W) of 5 neutral and 26 singly ionized gold (Au I and Au II, respectively) spectral lines have been measured in laboratory helium plasma at approximately 16,600 K electron temperature and 7.4 × 10 22 m - 3 electron density. Five Au I and ten Au II W values are reported for the first time. The Au II W values are compared with recent theoretical data, calculated based on a modified semi-empirical approach, and also with existing experimental W values. Our normalized Stark widths are six times higher than those measured in a laser-produced plasma. Possible explanation of this is recommended here. An agreement (within the accuracy of the experiment and uncertainties of the theoretical approach used) with the recently calculated W data was found in the 6p-7s Au II transition. The calculated hyperfine splitting for the five Au II lines in the 6s-6p transition is also presented. At the stated helium plasma conditions, Stark broadening has been found to be the dominant mechanism in the Au I and Au II line shape formation. A modified version of the linear low-pressure pulsed arc was used as a plasma source operated in helium, with gold atoms as impurities evaporated from the thin gold cylindrical plates located in the homogeneous part of the discharge, providing conditions free of self-absorption. This plasma source ensures good conditions for generation of excited gold ions due to Penning and charge exchange effects.

  4. Etude de la convection naturelle et de la stratification thermique dans une cavité inclinée et chauffée au milieu : application aux capteurs solaires autostockeurs

    OpenAIRE

    Swiatek, Marie

    2015-01-01

    Thermal regulation for dwellings in France makes the resort to renewable energy mandatory. Solar energy has an important potential regarding its availability, for both thermal and photovoltaic applications. However, due to its intermittency, there is a need for a storing device. Concerning solar thermal systems, Integrated Collector Storage Solar Water Heaters (ICSSWH) have the advantage of a simple design and use combined with reduced costs compared to more classical devices. These systems a...

  5. Application de la théorie des graphes au traitement de la carte géologique Applying the Theory of Graphs to the Treatment of Geological Maps

    Directory of Open Access Journals (Sweden)

    Bouillé F.

    2006-11-01

    Full Text Available La saisie des informations d'une carte géologique par les méthodes classiques (grilles ou relevés aléatoires de courbes ne constitue pas une base de données opérationnelle. Par contre, l'assimilation des limites géologiques à un graphe orienté répond aux critères d'optimalité (encombrement très réduit, temps minimal, fiabilité, et permet une digitalisation rationnelle de la carte, une bonne structuration du fichier, et la réalisation d'applications intéressantes : restitutions graphiques sélectives à toutes échelles, calculs de pendages, surfaces, volumes, études de corrélation. Nous avons donc établi une chaîne de traitement de la carte géologique dont chaque maillon (saisie des informations; contrôle, mise à jour, consultation, application opère sur un ou plusieurs graphes. Obtaining data from geological maps by conventional methods (grids or random curve plotting is not an operational data base. However, the comparison of geological boundaries with a directional graph meets criteria of optimalness (very small bulk, minimum time, reliability and makes it possible to digitize the map rationally, to structure the file properly and to achieve significant applications such as selective graph plotting on all scales, calculating dips, areas and volumes, and making correlotion analyses. Therefore, we worked out a geological map processing sequence in which each element (data acquisition, checking, updating, consulting, applications operates on one or several graphs.

  6. Embedding Raman Tags between Au Nanostar@Nanoshell for Multiplex Immunosensing.

    Science.gov (United States)

    Yang, Ting; Jiang, Jiang

    2016-09-01

    Novel Raman tags with various reporter molecules embedded in between gold nanostar (AuNS) and gold nanoshell are developed, showing significantly enhanced surface-enhanced Raman scattering intensity compared to gold nanoparticle-based composites. Immunoassay using these AuNS@tag@shell structures is highly specific with sensitivity down to 0.1 pg mL -1 , and is capable of multiplex detection, making them highly promising for biosensing applications. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  7. Proton beam writing and electroplating for the fabrication of high aspect ratio Au microstructures

    International Nuclear Information System (INIS)

    Yue Weisheng; Ren Yaping; Kan, Jeroen Anton van; Chiam, S.-Y.; Jian, Linke; Moser, Herbert O.; Osipowicz, Thomas; Watt, Frank

    2009-01-01

    We present an approach to fabricate tall high aspect ratio Au microstructures by means of proton beam direct writing. Combining proton beam direct writing and electroplating, we successfully produced gold structures with sub-micrometer lateral dimensions, structure heights in excess of 11 μm, and aspect ratios over 28. Sidewall quality of the Au structures was improved by lowering the process temperature to 20 deg. C when developing PMMA patterns with GG developer. The application of such structures as X-ray masks for deep X-ray lithography with synchrotron radiation was demonstrated.

  8. Test analysis of ancient Au and Ag coins using high energy PIXE

    International Nuclear Information System (INIS)

    Mommsen, H.; Schmittinger, T.

    1981-01-01

    The applicability of the high energy PIXE-method for nondestructive quantitative analyses without the use of standards is shown in a comparative analysis of three Au-coins and two Ag-coins. The Au-coins are of various provenance, the Ag-coins are from Athens (before 475 B.C.) and belong to the Asyut hoard. The aim of this test analysis is to show that the PIXE-method can give satisfactory results in a short time, even if applied in a very simple and straightforward way. (author)

  9. Renforcer la gestion financière publique au niveau du ...

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

    Ce projet aidera les comtés du Kenya à surmonter des défis importants découlant du transfert de certains pouvoirs détenus auparavant par le gouvernement central. L'objectif de l'équipe de recherche est de solidifier les capacités des gouvernements de comté afin de maintenir la discipline financière, d'améliorer l'efficacité ...

  10. Behaviour of `free-standing' hollow Au nanocages at finite temperatures: a BOMD study

    Science.gov (United States)

    Joshi, Krati; Krishnamurty, Sailaja

    2015-10-01

    Finite-temperature behaviour of a hollow golden cage (HGC) plays a crucialrole in its potential applications as a catalyst, drug delivery agent, contrasting agent and so on. This physico-chemical property of HGCs is not well understood so far. In that context, Born-Oppenheimer molecular dynamics (BOMD) simulations are performed on a well-known 'free-standing' HGC. The cluster considered in this study is the ground state Au18 cluster (a cage with a diameter of about >5.5 Å). The results thus obtained are compared with the BOMD simulation results reported earlier on Au32 icosahedron cage, a conformation with a diameter of nearly. The sphericity of both the clusters is studied using a shape deformation parameter as a function of time and temperature. These results are supplemented by radial distribution function at various temperatures. The observations and analysis of results indicate that, both the clusters retain an HGC conformation from 300 to 400 K, admitting structural fluxionality by the Au18 cluster. Remarkably, the Au18 cluster is able to maintain its hollowness and sphericity up to a high temperature of 1000 K. Underlying structural and electronic properties influencing the individualistic behaviour of cages are highlighted. Composition of the frontier molecular orbitals and the charge distribution play a crucial role in the finite-temperature behaviour of the Au cages. The conclusions are supplemented by supporting calculations on another degenerate ground state Au18 hollow cage and a well-known pyramidal Au18 cage at 300 and 400 K.

  11. Influence of Au Nanoparticle Shape on Au@Cu2O Heterostructures

    OpenAIRE

    Zhu, Jie; Lu, Na; Chen, Wei; Kong, Lina; Yang, Yun; Ma, Dekun; Huang, Shaoming

    2015-01-01

    Synthesis of metal-semiconductor heterostructures may allow the combination of function of the corresponding components and/or the enhanced performance resulting from the interactions between all the components. In this paper, Au@Cu2O core-shell heterostructures are prepared by a seed-growth method, using different-shaped Au nanocrystals as the seeds such as nanorods, octahedra, decahedra, dots, and nanocubes. The results revealed that the final structure of Au@Cu2O was greatly influenced by ...

  12. Alteration hydrothermale et deformation ductile des roches volcaniques acides associees au gisement sulfure de draa sfar (Jebilet Centrales, Maroc

    Directory of Open Access Journals (Sweden)

    Zinbi, Y.

    2005-12-01

    Full Text Available The volcanics and volcanoclastic rocks of Draa Sfar (Central Jebilet, Moroccan hercynian belt are affected by ductile stress and hydrothermal alteration accompanied by a weak degree of metamorphism (greenschist facies. Some N-S oriented shearing zones, affect locally these formations while being the site of an important hydrothermal activity. The consequences of these transformations from a non to slightly- deformed rhyodacite, show that through these ductile shearing zones: (1 the mineralogical assemblage of hydrothermal alteration is essentially formed by chlorite, sericite, quartz and magnetite; (2 the gradual increase of the alteration indexes is accompanied by the destruction of the phenocrists and the recrystallization of the matrix by phyllosilicates and quartz; (3 the progressive transfer of material is more intense in the more deformed zones where the values of Ti, Al and Zr remain constant. These shearing zones played a very important role in the circulation of fluids and the transformation of the rhyodacite of Draa Sfar.Les roches volcaniques et volcanoclastiques de Draa Sfar (Jebilet centrales, Maroc hercynien sont affectées par une déformation ductile accompagnée d’un métamorphisme de faible degré (faciès schistes verts et d’une altération hydrothermale. Des zones de cisaillement de direction N-S, ont affecté localement ces formations tout en étant vecteurs d’une importante activité hydrothermale. Le suivi de ces transformations à partir de la rhyodacite non ou peu déformée, montre qu’à travers ces zones de cisaillements ductiles : (1 l’assemblage minéralogique d’altération hydrothermale est formé essentiellement de chlorite, de séricite, de quartz et de magnétite ; (2 l’augmentation graduelle des indices d’altération s’exprime par la destruction des phénocristaux au profit d’une matrice recristallisée en phyllosilicates et quartz ; (3 le transfert progressif de la matière est plus intense

  13. Modification des conditions de maturation du raisin en Bourgogne viticole liée au réchauffement climatique

    Directory of Open Access Journals (Sweden)

    Malika Madelin

    2010-12-01

    Full Text Available Les répercussions du changement climatique, en particulier celles qui sont liées à l’augmentation des températures, s’observent dans de nombreux vignobles dans le monde. En Bourgogne, depuis 20 ans, cette évolution thermique modifie les conditions de la maturation, moment-clef pour la typicité du vin et sa signature terroir-millésime. Après une étude de l’évolution des températures en Bourgogne montrant en particulier une rupture en 1987-1988, une analyse comparée des conséquences phénologiques, à partir des données thermiques et des dates des stades de développement, est proposée pour deux sites côte-d’oriens en Côte et en Hautes-Côtes de Beaune (Savigny-lès-Beaune et La Rochepot. Les résultats montrent un transfert latitudinal et altitudinal des températures et des indices viticoles sur 20-30 ans, ainsi qu’un « double effet » du réchauffement climatique lors de la maturation, lié à l’augmentation des températures et au décalage temporel de cette période, qui se place de plus en plus souvent en août.Impacts of climate change such as those related to global warming, are observed in many vineyards in France and as in other vineyards in the world. In Burgundy, since 20 years, this evolution of the temperatures changes the maturation conditions, key time for "typicité" and signature of "terroir-millésime". After a study of the changes in Burgundy temperatures (which shows a thermal rupture in 1987-1988, a comparative analysis of the phenologic consequences is performed using thermal data and development dates for two vineyard sites in Côte and Hautes-Côtes de Beaune (Savigny-lès-Beaune et La Rochepot. The results show a latitudinal and vertical transfer of the temperatures and vine’s indexes over a 20-30 year period as well as a double effect of climate warming in the maturation stage attributed to the increase in temperatures and the time shift of this period (which occurs most often in August.

  14. A novel Au SINE sequence found in a gymnosperm.

    Science.gov (United States)

    Yagi, Eiki; Akita, Toru; Kawahara, Taihachi

    2011-01-01

    Although many SINE families have been identified in the animal kingdom, only a few SINE families have been identified in plants, and their distribution is somewhat limited. The Au SINE (Au) has been found discontinuously in basal angiosperms, monocots, and eudicots. In this study, we examined the presence of the Au in gymnosperms and ferns by PCR using internal primers for Au. As a result, we found Au in a gymnosperm species, Ephedra ciliata. Therefore, Au was supposed to be present in the common ancestor of angiosperms and gymnosperms. The Au in E. ciliate was 15 bp shorter than the consensus sequence, which is similar to the Au SINE found in Glycine. However, the 3'end of the Au found in E. ciliate was more similar to the 3'end of the Medicago-type Au than that of the Glycine-type Au. A phylogenetic tree indicated that the Au sequence from E. ciliate is more closely related to the sequence found in Glycine than that found in Medicago/Lotus. These results indicated that Au were present in both angiosperms and gymnosperms.

  15. Ultrasensitive enzyme-free electrochemical immunosensor based on hybridization chain reaction triggered double strand DNA@Au nanoparticle tag.

    Science.gov (United States)

    Ge, Yanqiu; Wu, Jie; Ju, Huangxian; Wu, Shuo

    2014-03-01

    An ultrasensitive enzyme-free electrochemical immunoassay was developed for detection of the fg/mL level carcinoembryonic antigen (CEA) by using a double strand DNA@Au nanoparticle (dsDNA@AuNP) tag and hexaammineruthenium(III) chloride (RuHex) as the electroactive indicator. The dsDNA@AuNP was synthesized by one-pot hybrid polymerization of dsDNA on initiator DNA modified AuNPs via hybridization chain reaction. The immunosensor was prepared by covalently cross-linking capture antibody on chitosan/AuNP nanocomposite modified glass carbon electrode. The AuNPs accelerated the electron transfer and led to high detection sensitivity. With a sandwich-type immunoreaction and a biotin-streptavidin affinity reaction, the dsDNA@AuNP tag was conjugated on the immunocomplex to bring a high amount of RuHex to the electrode surface via electrostatic interaction, resulting in an amplified electrochemical signal. Under optimal conditions, the proposed sensing platform showed a wide linear detection range from 10 fg/mL to 10 ng/mL along with a detection limit of 3.2 fg/mL for CEA. The immunosensor exhibited high sensitivity and good stability, showing a promising application in early cancer diagnosis and could be extended to sensitive electrochemical biosensing of other analytes. Copyright © 2013 Elsevier B.V. All rights reserved.

  16. Study of thermal diffusivity of nanofluids with bimetallic nanoparticles with Au(core)/Ag(shell) structure

    International Nuclear Information System (INIS)

    Gutierrez Fuentes, R.; Pescador Rojas, J.A.; Jimenez-Perez, J.L.; Sanchez Ramirez, J.F.; Cruz-Orea, A.; Mendoza-Alvarez, J.G.

    2008-01-01

    The thermal diffusivity of Au/Ag nanoparticles with core/shell structure, at different compositions (Au/Ag = 3/1, 1/1, 1/3, 1/6), was measured by using the mismatched mode of the dual-beam thermal lens (TL) technique. This study determines the effect of the bimetallic composition on the thermal diffusivity of the nanofluids. In these results we find a lineal increment of the nanofluid it thermal diffusivity when the Ag shell thickness is increased. Our results show that the nanoparticle structure is an important parameter to improve the heat transport in composites and nanofluids. These results could have importance for applications in therapies and photothermal deliberation of drugs. Complementary measurements with UV-vis spectroscopy and TEM, were used to characterize the Au(core)/Ag(shell) nanoparticles

  17. A highly crystalline single Au wire network as a high temperature transparent heater.

    Science.gov (United States)

    Rao, K D M; Kulkarni, Giridhar U

    2014-06-07

    A transparent conductor which can generate high temperatures finds important applications in optoelectronics. In this article, a wire network made of Au on quartz is shown to serve as an effective high temperature transparent heater. The heater has been fabricated by depositing Au onto a cracked sacrificial template. The highly interconnected Au wire network thus formed exhibited a transmittance of ∼87% in a wide spectral range with a sheet resistance of 5.4 Ω □(-1). By passing current through the network, it could be joule heated to ∼600 °C within a few seconds. The extraordinary thermal performance and stability owe much to the seamless junctions present in the wire network. Furthermore, the wire network gets self-annealed through joule heating as seen from its increased crystallinity. Interestingly, both transmittance and sheet resistance improved following annealing to 92% and 3.2 Ω □(-1), respectively.

  18. Didaktik des außerschulischen Lernens

    CERN Document Server

    Sauerborn, Petra

    2012-01-01

    Kernprobleme schulischer Bildung sind die zunehmenden Verluste an Realitäts- und Praxisbezug sowie die einseitige Betonung der fachwissenschaftlichen Kenntnisse. In jüngster Zeit werden insbesondere moderne didaktisch-methodische Konzepte näher diskutiert und praktiziert. So finden sich etwa die Stichwörter Handlungsorientierter Unterricht und Offener Unterricht in der fachdidaktischen Diskussion wieder. Eine wesentlich aktuellere Form stellt das außerschulische Lernen dar. Ein modernes pädagogisches Verständnis sieht den Unterricht heute nicht mehr als ausschließliche Tätigkeit des Lehrers an, sondern als Aktivität der Lernenden. Außerschulisches Lernen beschreibt die originale Begegnung im Unterricht außerhalb des Klassenzimmers. An außerschulischen Lernorten findet eine unmittelbare AuseinanderSetzung des Lernenden mit seiner räumlichen Umgebung statt. Charakteristisch sind hierbei vor allem die aktive(Mit-)Gestaltung sowie die eigenständige Wahrnehmung mehrperspektivischer Bildungsinhalte d...

  19. Melamine structures on the Au(111) surface

    NARCIS (Netherlands)

    Silly, Fabien; Shaw, Adam Q.; Castell, Martin R.; Briggs, G. A. D.; Mura, Manuela; Martsinovich, Natalia; Kantorovich, Lev

    2008-01-01

    We report on a joint experimental and theoretical study of the ordered structures of melamine molecules formed on the Au(111)-(22 x root 3) surface. Scanning tunneling microscopy (STM) images taken under UHV conditions reveal two distinct monolayers one of which has never been reported before on

  20. Surface structure of AU3Cu(001)

    DEFF Research Database (Denmark)

    Eckstein, G.A.; Maupai, S.; Dakkouri, A.S.

    1999-01-01

    The surface morphology, composition, and structure of Au3Cu(001) as determined by scanning tunneling microscopy and surface x-ray diffraction are presented. Atomic resolution STM images reveal distinctive geometric features. The analysis of the surface x-ray diffraction data provides clear evidence...... for the surface structure. [S0163-1829(99)04535-X]....

  1. ( Vigna subterranea (L.) Verdcourt) au Burkina Faso

    African Journals Online (AJOL)

    Aperçu de la culture du voandzou ( Vigna subterranea (L.) Verdcourt) au Burkina Faso: enjeux et perspectives d'amélioration de sa productivité. ... Foliar diseases and insects in stock are major biotic constraints. Producers retain the seed in cans tightly closed. The average cycle of cultivated varieties is 90 days. The favorite ...

  2. Au-nano-delci in njihova uporaba

    OpenAIRE

    Rudolf, Rebeka; Zorko, Lidija; Anžel, Ivan

    2012-01-01

    Razvoj tehnik za sintezo Au-nano delcev z določeno velikostjo, obliko in sestavo je izziv in pomembno področje raziskav v nanotehnologiji. Zlati nanodelci so namreč atraktivni zaradi potencialne uporabe v elektrokemiji in medicini, kot tudi za proizvodnjo različnih nano-naprav.

  3. HYPERTENSION AU COURS DE LA GROSSESSE: Aspects ...

    African Journals Online (AJOL)

    hypertension soit une prévalence de 8,2%. Cette pathologie survient dans notre .... consultations prénatales ou le post-partum. Sur le plan clinique, la ... des patientes étaient au terme de leur grossesse alors que 22.11%, avaient un âge ...

  4. Multifunctional BSA-Au nanostars for photoacoustic imaging and X-ray computed tomography.

    Science.gov (United States)

    Zu, Lihui; Liu, Lin; Qin, Yeshan; Liu, Hongguang; Yang, Haishan

    2016-10-01

    We report the synthesis and characterization of bovine serum albumin-capped Au nanostars (BSA-AuNSs) for dual-modal computed tomography (CT)/photoacoustic (PA) imaging application. The BSA-AuNSs have an average size of 85nm, and a surface plasmon resonance (SPR) peak at approximately 770nm. They have excellent biocompatibility, good X-ray attenuation, and great PA contrast enhancement properties. When injected intravenously, liver signal markedly increases in both CT and PA modalities. The in vivo biodistribution studies and pathology results showed that the BSA-AuNSs were mainly excreted through the liver and intestines with no obvious biotoxicity. These results indicate that BSA-AuNSs have high potential to be used as dual-modal CT/PA imaging contrast agents or further used to develop targeted probes. This preliminary study suggests that PA tomography may be used to non-invasively trace the kinetics and biodistribution of the nanoparticles. Copyright © 2016 Elsevier Inc. All rights reserved.

  5. Au/CeO2-chitosan composite film for hydrogen peroxide sensing

    International Nuclear Information System (INIS)

    Zhang Wei; Xie Guoming; Li Shenfeng; Lu Lingsong; Liu Bei

    2012-01-01

    Au nanoparticles (AuNPs) were in situ synthesized at the cerium dioxide nanoparticles (CeO 2 NPs)-chitosan (CS) composite film by one-step direct chemical reduction, and the resulting Au/CeO 2 -CS composite were further modified for enzyme immobilization and hydrogen peroxide (H 2 O 2 ) biosensing. Transmission electron microscopy (TEM), energy dispersive X-ray spectroscopy (EDX), UV-vis spectra and electrochemical techniques have been utilized for characterization of the prepared composite. The stepwise assembly process and electrochemical performances of the biosensor were characterized by means of cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and typical amperometric response (i-t). The Au/CeO 2 -CS composite exhibited good conductibility and biocompatibility, and the developed biosensor exhibited excellent response to hydrogen peroxide in the linear range of 0.05-2.5 mM (r = 0.998) with the detection limit of 7 μM (S/N = 3). Moreover, the biosensor presented high affinity (K m app =1.93mM), good reproducibility and storage stability. All these results demonstrate that the Au/CeO 2 -CS composite film can provide a promising biointerface for the biosensor designs and other biological applications.

  6. A Facile and Green Synthetic Route for Preparation of Heterostructure Fe3O4@Au Nanocomposites

    Directory of Open Access Journals (Sweden)

    Xie Liping

    2017-01-01

    Full Text Available Magnetic nanoparticles offer many exciting opportunities in biology and biomedicine, such as magnetic resonance imaging, magnetic hyperthermia therapy, biomedical diagnosis. The synthesis of multifunctional magnetic nanocomposites that possess water-solubility, magnetic properties and optical stability by a green method at room temperature in aqueous phase is still an unmet need. Here, we developed a simple and green method for preparing Fe3O4@Au integrated the super-paramagnetic and optical properties by seed-mediated growth at mild condition in aqueous phase. The amphiphilic, non-ionic and nontoxic polymer poly(vinylpyrrolidone (PVP was used as a coupling agent for synthesis of Fe3O4@Au nanocomposites, which avoided the direct connection of Au and Fe3O4, and improved the saturation magnetization values of Fe3O4@Au to 40 emu/g at room temperature. We anticipate that the multifunctional Fe3O4@Au nanocomposites with high magnetic and good optical properties will provide a platform for potential diagnostic and therapeutic biomedical applications.

  7. Structural studies of Au-Pd bimetallic nanoparticles by a genetic algorithm method

    Science.gov (United States)

    Shao, Gui-Fang; Tu, Na-Na; Liu, Tun-Dong; Xu, Liang-You; Wen, Yu-Hua

    2015-06-01

    Metallic nanoparticles have attracted particular interests due to their excellent electronic, catalytic and optical properties over the past decades. Atomic-level understanding of structural characteristics of metallic nanoparticles is of great importance for their syntheses and applications because the structural characteristics strongly determine their chemical and physical properties. In this article, we systematically investigated the structural stability and structural features of Au-Pd nanoparticles by using the genetic algorithm with the quantum correction Sutton-Chen potentials. Layered coordinate ranking method and an effective fitness function have been introduced into the genetic algorithm to enhance its searching ability of low-energy configurations. Here were addressed eight representative nanoshapes including single-crystalline and multiple-twinned structures. The results reveal that the developed genetic algorithm exhibits superior searching ability. In all polyhedra, the truncated octahedron possessed the best stability, while the icosahedron did the worst. Moreover, segregation of Au to the surface and that of Pd to the core were disclosed in these polyhedral Au-Pd nanoparticles. Particularly, for Au composition of 50%, the optimized structures of Au-Pd nanoparticles were predicted to exhibit core-shell structures.

  8. Biosynthesis and stabilization of Au and Au–Ag alloy nanoparticles by fungus, Fusarium semitectum

    Directory of Open Access Journals (Sweden)

    Balaji Dasaratrao Sawle, Basavaraja Salimath, Raghunandan Deshpande, Mahesh Dhondojirao Bedre, Belawadi Krishnamurthy Prabhakar and Abbaraju Venkataraman

    2008-01-01

    Full Text Available Crystallized and spherical-shaped Au and Au–Ag alloy nanoparticles have been synthesized and stabilized using a fungus, F . semitectum in an aqueous system. Aqueous solutions of chloroaurate ions for Au and chloroaurate and Ag+ ions (1 : 1 ratio for Au–Ag alloy were treated with an extracellular filtrate of F . semitectum biomass for the formation of Au nanoparticles (AuNP and Au–Ag alloy nanoparticles (Au–AgNP. Analysis of the feasibility of the biosynthesized nanoparticles and core–shell alloy nanoparticles from fungal strains is particularly significant. The resultant colloidal suspensions are highly stable for many weeks. The obtained Au and Au–Ag alloy nanoparticles were characterized by the surface plasmon resonance (SPR peaks using a UV-vis spectrophotometer, and the structure, morphology and size were determined by Fourier transform infrared spectroscopy (FTIR, x-ray diffraction (XRD, and transmission electron microscopy (TEM. Possible optoelectronics and medical applications of these nanoparticles are envisaged.

  9. Sensitive electrochemical detection of nitric oxide based on AuPt and reduced graphene oxide nanocomposites.

    Science.gov (United States)

    Liu, Zhonggang; Forsyth, Heidi; Khaper, Neelam; Chen, Aicheng

    2016-06-20

    Since nitric oxide (NO) plays a critical role in many biological processes, its precise detection is essential toward an understanding of its specific functions. Here we report on a facile and environmentally compatible strategy for the construction of an electrochemical sensor based on reduced graphene oxide (rGO) and AuPt bimetallic nanoparticles. The prepared nanocomposites were further employed for the electroanalysis of NO using differential pulse voltammetry (DPV) and amperometric methods. The dependence of AuPt molar ratios on the electrochemical performance was investigated. Through the combination of the advantages of the high conductivity from rGO and highly electrocatalytic activity from AuPt bimetallic nanoparticles, the AuPt-rGO based NO sensor exhibited a high sensitivity of 7.35 μA μM(-1) and a low detection limit of 2.88 nM. Additionally, negligible interference from common ions or organic molecules was observed, and the AuPt-rGO modified electrode demonstrated excellent stability. Moreover, this optimized electrochemical sensor was practicable for efficiently monitoring the NO released from rat cardiac cells, which were stimulated by l-arginine (l-arg), showing that stressed cells generated over 10 times more NO than normal cells. The novel sensor developed in this study may have significant medical diagnostic applications for the prevention and monitoring of disease.

  10. Au-Ag hybrid nanoparticle patterns of tunable size and density on glass and polymeric supports.

    Science.gov (United States)

    Kruss, Sebastian; Srot, Vesna; van Aken, Peter A; Spatz, Joachim P

    2012-01-17

    This paper describes a method to pattern surfaces with Au-Ag hybrid nanoparticles. We used block copolymer micelle lithography of Au nanoparticles and electroless deposition of Ag. The combination of these two methods enables independent tuning of nanoparticle spacing and Ag-shell size. For this purpose, 8 nm large patterned Au nanoparticle seeds served as nuclei for the electroless deposition of silver that is based on a modified Tollens process with glucose. By adjusting the reaction conditions, specific growth of Ag on top of the Au seeds has been accomplished and analyzed by SEM, HRTEM, XEDS, and UV-vis spectroscopy. We could show that this versatile and green method is feasible on glass as well as on biomedical-relevant polymers like poly(ethylene glycol) hydrogels and amorphous Teflon. In conclusion, this method provides a new route to pattern glass and polymeric surfaces with Au-Ag hybrid nanoparticles. It will have many uses in applications such as surface enhanced Raman spectroscopy (SERS) or antimicrobial coatings for which hybrid nanoparticle density, size, and morphology are important. © 2011 American Chemical Society

  11. Irrigation et intensification de la production agricole au Sahel ...

    African Journals Online (AJOL)

    Irrigation et intensification de la production agricole au Sahel : perceptions paysannes sur la double riziculture et les variétés de riz utilisées sur les aménagements hydro - agricoles au Niger.

  12. Molecules on vicinal Au surfaces studied by scanning tunnelling microscopy

    International Nuclear Information System (INIS)

    Kroeger, J; Neel, N; Jensen, H; Berndt, R; Rurali, R; Lorente, N

    2006-01-01

    Using low-temperature scanning tunnelling microscopy and spectroscopy we investigated the adsorption characteristics of 3,4,9,10-perylenetetracarboxylic-dianhydride and fullerenes on Au(788), Au(433), and Au(778). On Au(788) and Au(778), 3,4,9,10-perylenetetracarboxylic-dianhydride exhibits three coexisting superstructures, which do not reflect the periodicity of the hosting substrate. The adsorption on Au(433) leads to the formation of molecule chains along the step edges after annealing the sample. Fullerene molecules on Au(788) arrange in a mesh of islands, which extends over several hundreds of nanometres with an extraordinarily high periodicity. A combination of fullerene adsorption and annealing leads to facetting of Au(433) and the formation of extraordinarily long fullerene stripes

  13. Three-particle correlations from parton cascades in Au+Au collisions

    International Nuclear Information System (INIS)

    Ma, G.L.; Ma, Y.G.; Zhang, S.; Cai, X.Z.; Chen, J.H.; He, Z.J.; Huang, H.Z.; Long, J.L.; Shen, W.Q.; Shi, X.H.; Zhong, C.; Zuo, J.X.

    2007-01-01

    We present a study of three-particle correlations among a trigger particle and two associated particles in Au+Au collisions at s NN =200 GeV using a multi-phase transport model (AMPT) with both partonic and hadronic interactions. We found that three-particle correlation densities in different angular directions with respect to the triggered particle ('center', 'cone', 'deflected', 'near' and 'near-away') increase with the number of participants. The ratio of 'deflected' to 'cone' density approaches to 1.0 with the increasing of number of participants, which indicates that partonic Mach-like shock waves can be produced by strong parton cascades in central Au+Au collisions

  14. Solution-dispersible Au nanocube dimers with greatly enhanced two-photon luminescence and SERS

    Science.gov (United States)

    Liu, Xiao-Li; Liang, Shan; Nan, Fan; Yang, Zhong-Jian; Yu, Xue-Feng; Zhou, Li; Hao, Zhong-Hua; Wang, Qu-Quan

    2013-05-01

    We report the synthesis of 43-nm diameter Au nanocube dimers by using Ag+ ions as competitive ligands to freeze l-cysteine-induced assembly process of the nanocubes to a desirable stage. Ascribed to the resonant interparticle coupling with an newly arising plasmon band at 710 nm and local field enhancement, the two-photon luminescence intensity of the Au nanocube dimers in solution was over 20 times stronger than that of the monomers in the wavelength range 555-620 nm. Furthermore, by coupling Raman tags onto the nanocube surface, a solution-based surface-enhanced Raman scattering (SERS) of the nanocube dimers had an enhancement factor of over 10 times compared to the isolated nanocubes. To sum up, with high stability in solution and attractive optical properties, the Au nanocube dimers have potential applications in in vivo bio-imaging and solution-based SERS.We report the synthesis of 43-nm diameter Au nanocube dimers by using Ag+ ions as competitive ligands to freeze l-cysteine-induced assembly process of the nanocubes to a desirable stage. Ascribed to the resonant interparticle coupling with an newly arising plasmon band at 710 nm and local field enhancement, the two-photon luminescence intensity of the Au nanocube dimers in solution was over 20 times stronger than that of the monomers in the wavelength range 555-620 nm. Furthermore, by coupling Raman tags onto the nanocube surface, a solution-based surface-enhanced Raman scattering (SERS) of the nanocube dimers had an enhancement factor of over 10 times compared to the isolated nanocubes. To sum up, with high stability in solution and attractive optical properties, the Au nanocube dimers have potential applications in in vivo bio-imaging and solution-based SERS. Electronic supplementary information (ESI) available. See DOI: 10.1039/c3nr01170d

  15. Strangeness production in Au+Au collisions at the AGS: recent results from E917

    International Nuclear Information System (INIS)

    Chang, W.-C.; Back, B.B.; Betts, R.R.; Britt, H.C.; Chang, W.C.; Gillitzer, A.; Henning, W.F.; Hofman, D.J.; Holzman, B.; Nanal, V.; Wuosmaa, A.H.

    1999-01-01

    Strangeness production in Au+Au collisions has been measured via the yields of K + , K - at 6, 8 AGeV and of bar Λ at 10.8 AGeV beam kinetic energy in experiment E917. By varying the collision centrally and beam energy, a systematic search for indications of new phenomena and in-medium effects under high baryon density is undertaken

  16. Bonheur et progrès : mesurer le bien-être au Bhoutan et au Canada ...

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

    31 janv. 2011 ... Mesurer le bien-être. Au Bhoutan, ce tableau de bord porte un nom plein de charme. C'est le bonheur national brut (BNB). Le royaume est-himalayen, bouddhiste, compte environ 800 000 sujets. Enclavé entre les deux pays les plus populeux de la planète, il vient de mettre fin au long isolement qu'il s'était ...

  17. Results from experiment E917 for Au + Au collisions at the AGS.

    Energy Technology Data Exchange (ETDEWEB)

    Back, B. B.; Betts, R. R.; Chang, J.; Chang, W. C.; E917 Collaboration; Gillitzer, A.; Henning, W. F.; Hofman, D. J.; Nanal, V.; Wuosmaa, A. H.

    1999-08-04

    The effects of baryon stopping and its resulting energy deposition on the dynamics of Au + Au collisions at 6, 8 and 10.8 GeV/nucleon are explored with recent results from the AGS experiment E917. Current analyses of stopping, collective flow signals and HBT parameters are presented. Strangeness and anti-baryon production is examined using the yields of anti-lambdas and anti-protons.

  18. A first look at Au·Au collisions at RHIC energies using the PHOBOS ...

    Indian Academy of Sciences (India)

    A first look at Au·Au collisions at RHIC energies using the PHOBOS detector. BIRGER BACK1, for the PHOBOS Collaboration. M D Baker2, D S Barton2, R R Betts6, R Bindel7, A Budzanowski3, W Busza4,. A Carroll2, J Corbo2, M P Decowski4, E Garcia6, N George1, K Gulbrandsen4, S Gushue2,. C Halliwell6, J Hamblen8, ...

  19. Comparative toxicity study of Ag, Au, and Ag-Au bimetallic nanoparticles on Daphnia magna.

    Science.gov (United States)

    Li, Ting; Albee, Brian; Alemayehu, Matti; Diaz, Rocio; Ingham, Leigha; Kamal, Shawn; Rodriguez, Maritza; Bishnoi, Sandra Whaley

    2010-09-01

    A comparative assessment of the 48-h acute toxicity of aqueous nanoparticles synthesized using the same methodology, including Au, Ag, and Ag-Au bimetallic nanoparticles, was conducted to determine their ecological effect in freshwater environments through the use of Daphnia magna, using their mortality as a toxicological endpoint. D. magna are one of the standard organisms used for ecotoxicity studies due to their sensitivity to chemical toxicants. Particle suspensions used in toxicity testing were well-characterized through a combination of absorbance measurements, atomic force or electron microscopy, flame atomic absorption spectrometry, and dynamic light scattering to determine composition, aggregation state, and particle size. The toxicity of all nanoparticles tested was found to be dose and composition dependent. The concentration of Au nanoparticles that killed 50% of the test organisms (LC(50)) ranged from 65-75 mg/L. In addition, three different sized Ag nanoparticles (diameters = 36, 52, and 66 nm) were studied to analyze the toxicological effects of particle size on D. magna; however, it was found that toxicity was not a function of size and ranged from 3-4 μg/L for all three sets of Ag nanoparticles tested. This was possibly due to the large degree of aggregation when these nanoparticles were suspended in standard synthetic freshwater. Moreover, the LC(50) values for Ag-Au bimetallic nanoparticles were found to be between that of Ag and Au but much closer to that of Ag. The bimetallic particles containing 80% Ag and 20% Au were found to have a significantly lower toxicity to Daphnia (LC(50) of 15 μg/L) compared to Ag nanoparticles, while the toxicity of the nanoparticles containing 20% Ag and 80% Au was greater than expected at 12 μg/L. The comparison results confirm that Ag nanoparticles were much more toxic than Au nanoparticles, and that the introduction of gold into silver nanoparticles may lower their environmental impact by lowering the amount

  20. Des institutions au service de villes sûres et inclusives au Venezuela

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

    Caracas, au Venezuela, est l'une des villes les plus violentes au monde; il s'y commet 122 homicides par tranche de 100 000 habitants. Selon les experts en violence urbaine, les inégalités sociales et la disparité des revenus sont étroitement liées à l'ampleur de la violence, mais cette théorie ne tient pas dans le cas ...

  1. Mécanismes de la déformation en zones de plate-forme : méthode et application au bassin de Paris. Deuxième partie Deformation Mechanisms in Platform Zones: Method and Application to the Paris Basin. Part Two

    Directory of Open Access Journals (Sweden)

    Tremolieres P.

    2006-11-01

    Full Text Available On se propose, dans cet article, de présenter une méthode d'étude structurale qui prend en compte aussi bien les données de terrain que celles de subsurface. L'étude des déformations par l'analyse microtectonique permet en général de remonter à la distribution des contraintes pour une période correspondant grossièrement aux phases de déformation paroxysmales. Par contre, dans les intervalles compris entre ces phases paroxysmales ou même lors des phases en distension, l'apport de l'analyse microtectonique est moindre ; dans ces cas, l'étude des variations d'épaisseur des sédiments, associée à une bonne connaissance de l'orientation des failles du substratum et de leur pendage permet parfois de préciser la nature des contraintes et, dans les conditions les plus favorables, d'estimer les directions de raccourcissement ou d'allongement. Dans une première partie, on développe l'aspect méthodologique en essayant de préciser : - la place de la microtectonique en Géologie structurale et les principaux faciès sédimentaires favorables à son utilisation ; - l'influence des principaux facteurs intervenant sur les déformations des séries sédimentaires en zone de plate-forme. Dans une deuxième partie, on insiste sur l'intérêt de l'analyse structurale, méthode souvent rapide et peu coûteuse, en exploration pétrolière. Notre expérience personnelle nous pousse à développer certains sujets, comme la réorientation des contraintes à proximité de certains accidents, la stylolithisation, etc. Enfin, on montre une application de la méthode au bassin de Paris. Il ne s'agit pas d'une étude à caractère exhaustif, mais on esssaye d'exposer, à l'aide de quelques exemples souvent très schématisés, la complémentarité de la micro-tectonique, d'une part, et de l'étude des variations d'épaisseurs des sédiments d'autre part. This article attempts to describe a structural analysis method which takes both field and subsurface

  2. Mécanismes de la déformation en zones de plate-forme : méthode et application au bassin de Paris. Première partie Deformation Mechanisms in Platform Zones: Method and Application to the Paris Basin. Part One

    Directory of Open Access Journals (Sweden)

    Tremolieres P.

    2006-11-01

    Full Text Available On se propose, dans cet article, de présenter une méthode d'étude structurale qui prend en compte aussi bien les données de terrain que celles de subsurface. L'étude des déformations par l'analyse microtectonique permet en général de remonter à la distribution des contraintes pour une période correspondant grossièrement aux phases de déformation paroxysmales. Par contre, dans les intervalles compris entre ces phases paroxysmales ou même lors des phases en distension, l'apport de l'analyse microtectonique est moindre ; dans ces cas, l'étude des variations d'épaisseur des sédiments, associée à une bonne connaissance de l'orientation des failles du substratum et de leur pendage permet parfois de préciser la nature des contraintes et, dans les conditions les plus favorables, d'estimer les directions de raccourcissement ou d'allongement. Dans une première partie, on développe l'aspect méthodologique en essayant de préciser : - la place de la microtectonique en Géologie structurale et les principaux faciès sédimentaires favorables à son utilisation ; - l'influence des principaux facteurs intervenant sur les déformations des séries sédimentaires en zone de plate-forme. Dans une deuxième partie, on insiste sur l'intérêt de l'analyse structurale, méthode souvent rapide et peu coûteuse, en exploration pétrolière. Notre expérience personnelle nous pousse à développer certains sujets, comme la réorientation des contraintes à proximité de certains accidents, la stylolithisation, etc. Enfin, on montre une application de la méthode au bassin de Paris. Il ne s'agit pas d'une étude à caractère exhaustif, mais on esssaye d'exposer, à l'aide de quelques exemples souvent très schématisés, la complémentarité de la micro-tectonique, d'une part, et de l'étude des variations d'épaisseurs des sédiments d'autre part. This article attempts to describe a structural analysis method which takes both field and subsurface

  3. The effect of Au amount on size uniformity of self-assembled Au nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Chen, S-H; Wang, D-C; Chen, G-Y; Chen, K-Y [Graduate School of Engineering Science and Technology, National Yunlin University of Science and Technology, Taiwan (China)

    2008-03-15

    The self-assembled fabrication of nanostructure, a dreaming approach in the area of fabrication engineering, is the ultimate goal of this research. A finding was proved through previous research that the size of the self-assembled gold nanoparticles could be controlled with the mole ratio between AuCl{sub 4}{sup -} and thiol. In this study, the moles of Au were fixed, only the moles of thiol were adjusted. Five different mole ratios of Au/S with their effect on size uniformity were investigated. The mole ratios were 1:1/16, 1:1/8, 1:1, 1:8, 1:16, respectively. The size distributions of the gold nanoparticles were analyzed by Mac-View analysis software. HR-TEM was used to derive images of self-assembled gold nanoparticles. The result reached was also the higher the mole ratio between AuCl{sub 4}{sup -} and thiol the bigger the self-assembled gold nanoparticles. Under the condition of moles of Au fixed, the most homogeneous nanoparticles in size distribution derived with the mole ratio of 1:1/8 between AuCl{sub 4}{sup -} and thiol. The obtained nanoparticles could be used, for example, in uniform surface nanofabrication, leading to the fabrication of ordered array of quantum dots.

  4. A nanocomposite of Au-AgI core/shell dimer as a dual-modality contrast agent for x-ray computed tomography and photoacoustic imaging

    Energy Technology Data Exchange (ETDEWEB)

    Orza, Anamaria; Wu, Hui; Li, Yuancheng; Mao, Hui, E-mail: hmao@emory.edu, E-mail: Xiangyang.Tang@emory.edu [Department of Radiology and Imaging Sciences and Center for Systems Imaging, Emory University School of Medicine, Atlanta, Georgia 30322 (United States); Yang, Yi; Tang, Xiangyang, E-mail: hmao@emory.edu, E-mail: Xiangyang.Tang@emory.edu [Department of Radiology and Imaging Sciences, Emory University School of Medicine, Atlanta, Georgia 30322 (United States); Feng, Ting; Wang, Xueding [Department of Biomedical Engineering, University of Michigan School of Medicine, Ann Arbor, Michigan 48109 (United States); Yang, Lily [Department of Surgery, Emory University School of Medicine, Atlanta, Georgia 30322 (United States)

    2016-01-15

    Purpose: To develop a core/shell nanodimer of gold (core) and silver iodine (shell) as a dual-modal contrast-enhancing agent for biomarker targeted x-ray computed tomography (CT) and photoacoustic imaging (PAI) applications. Methods: The gold and silver iodine core/shell nanodimer (Au/AgICSD) was prepared by fusing together components of gold, silver, and iodine. The physicochemical properties of Au/AgICSD were then characterized using different optical and imaging techniques (e.g., HR- transmission electron microscope, scanning transmission electron microscope, x-ray photoelectron spectroscopy, energy-dispersive x-ray spectroscopy, Z-potential, and UV-vis). The CT and PAI contrast-enhancing effects were tested and then compared with a clinically used CT contrast agent and Au nanoparticles. To confer biocompatibility and the capability for efficient biomarker targeting, the surface of the Au/AgICSD nanodimer was modified with the amphiphilic diblock polymer and then functionalized with transferrin for targeting transferrin receptor that is overexpressed in various cancer cells. Cytotoxicity of the prepared Au/AgICSD nanodimer was also tested with both normal and cancer cell lines. Results: The characterizations of prepared Au/AgI core/shell nanostructure confirmed the formation of Au/AgICSD nanodimers. Au/AgICSD nanodimer is stable in physiological conditions for in vivo applications. Au/AgICSD nanodimer exhibited higher contrast enhancement in both CT and PAI for dual-modality imaging. Moreover, transferrin functionalized Au/AgICSD nanodimer showed specific binding to the tumor cells that have a high level of expression of the transferrin receptor. Conclusions: The developed Au/AgICSD nanodimer can be used as a potential biomarker targeted dual-modal contrast agent for both or combined CT and PAI molecular imaging.

  5. Properties and electrochemical behaviors of AuPt alloys prepared by direct-current electrodeposition for lithium air batteries

    International Nuclear Information System (INIS)

    Zhang, Jinqiu; Li, Da; Zhu, Yiming; Chen, Miaomiao; An, Maozhong; Yang, Peixia; Wang, Peng

    2015-01-01

    AuPt catalyst has a prospective application in a lithium air battery because of its bi-function on catalyzing Oxygen Reduction Reaction (ORR) and Oxygen Evolution Reaction (OER). Electrodeposition is an in-situ convenient technology for catalyst preparation without chemical residue. In an acid electrolyte, AuPt alloy catalysts were electrodeposited on carbon paper. The effect of main salt concentration, electrodeposition time and current density were studied by deposit micromorphology observation, structure analyses and composition testing. Catalytic abilities of AuPt alloys were measured by cyclic voltammetry (CV) in an ionic liquid of EMI-TFSI/Li-TFSI [1- Ethyl - 3- methylimidazolium–bis (trifluoromethanesulphonyl) imide/lithium–bis (trifluoromethanesulphonyl) imide]. The electrochemical behaviors of Au, Pt and AuPt deposits were also measured. An optimized direct-current electrodeposition process of getting high active AuPt catalyst is concluded, which is an aqueous solution containing 6.7∼10 mmol · L −1 HAuCl 4 , 10∼13.3 mmol · L −1 H 2 PtCl 6 and 0.5 mol · L −1 H 2 SO 4 as the electrolyte, current density of 20mA · cm −2 and electrodeposition time of 8∼34 s. The co-deposition of AuPt alloy is an irregular co-deposition controlled by diffusion, while gold atoms enter the platinum’s crystal lattice in the structure of AuPt alloy. The increase of the concentration of H 2 PtCl 6 in the electrolyte, the extension of the electrodeposition time or the raise of the current density can improve the content of Pt in the deposit. The clusters’ diameters of AuPt catalysts decrease to 150∼250 nm by adjusting current densities during electrodeposition

  6. Programmation religieuse au Moyen-Orient : analyse du contenu de ...

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

    Intégration des militants islamistes au processus politique : Hamas palestinien. La victoire éclatante du Hamas aux élections de janvier 2006 porte à s'interroger sur l'intégration des militants islamistes au système politique palestinien. Voir davantageIntégration des militants islamistes au processus politique : Hamas ...

  7. A reagentless amperometric immunosensor based on nano-au and ...

    African Journals Online (AJOL)

    Jane

    2011-08-01

    Aug 1, 2011 ... In this paper, carboxyl-ferrocene (Fc-COOH) was explored to label alphafetoprotein antibody (anti-AFP), which was then mixed with AU nanoparticles (nano-Au) and multi-walled carbon nanotubes (MWCNTs) dispersed by chitosan (CS) to form the nano-Au/MWCNTs/anti-AFP-Fc chitosan composite.

  8. Magnetic depth profiling of Fe/Au multilayer using neutron ...

    Indian Academy of Sciences (India)

    We present unpolarized and polarized neutron reflectometry data on Fe/Au multilayer sample for characterizing the layer structure and magnetic moment density profile. Fe/Au multilayer shows strong spin-dependent scattering at interfaces, making it a prospective GMR material. Fe/Au multilayer with bilayer thickness of 130 ...

  9. Viscoelastic nature of Au nanoparticle–PDMS nanocomposite gels

    Indian Academy of Sciences (India)

    A stable gel of Au nanoparticles in polydimethylsiloxane (PDMS) nanocomposite is prepared by employing the curing agent of PDMS elastomer as a reducing agent for the formation of Au nanoparticles by an in-situ process. The viscoelastic nature of these gels is very sensitive to the Au nanoparticle loading and the ...

  10. Preparation and use of 195m Au-containing liquid

    International Nuclear Information System (INIS)

    Panek, K.J.

    1983-01-01

    A 195m Au-containing liquid is prepared by adsorbing 195m-Hg on an adsorption agent and then eluting the daughter radioisotope 195m-Au. A radioisotope generator and the adsorption agent to be used in preparation of 195m Au-containing liquids are also claimed

  11. The point-defect of carbon nanotubes anchoring Au nanoparticles

    DEFF Research Database (Denmark)

    Lv, Y. A.; Cui, Y. H.; Li, X. N.

    2010-01-01

    between Au clusters and CNTs by means of density functional theory calculations. Both experimental and theoretical studies show that point defects are the anchoring sites of Au nanoparticles. The mechanisms of enhanced bond between Au and CNTs via the point defects are explained by the analysis of density...

  12. A reagentless amperometric immunosensor based on nano-au and ...

    African Journals Online (AJOL)

    In this paper, carboxyl-ferrocene (Fc-COOH) was explored to label alphafetoprotein antibody (anti-AFP), which was then mixed with AU nanoparticles (nano-Au) and multi-walled carbon nanotubes (MWCNTs) dispersed by chitosan (CS) to form the nano-Au/MWCNTs/anti-AFP-Fc chitosan composite. After that, the composite ...

  13. An oscillator based on a single Au nanocluster

    Science.gov (United States)

    Gorshkov, O. N.; Filatov, D. O.; Antonov, D. A.; Antonov, I. N.; Shenina, M. E.; Pavlov, D. A.

    2017-01-01

    Metal nanoclusters embedded into the ultrathin dielectric films attracted much attention in recent years due to their unusual electronic, optical, etc., properties differing from those of the bulk metals essentially and, hence, to the prospects of their applications in novel nanoelectronic, single electronic, non-volatile memory, etc., devices. Here, we report on the experimental observation of the electrical oscillations in an oscillating loop connected to a contact of a conductive probe of an Atomic Force Microscope to a tunnel-transparent ( ˜6.5 nm thick) yttria stabilized zirconia film with embedded Au nanoclusters on the Si substrate. The oscillations were attributed to the negative differential resistance of the probe-to-sample contact originating from the resonant electron tunnelling between the probe and the Si substrate via the quantum confined electron energy levels in small ( ≈2.5 nm in diameter) Au nanoclusters. This observation demonstrates the prospects of building an oscillator nanoelectronic device based on an individual nanometer-sized metal nanocluster.

  14. Jet-Hadron Correlations in √sNN =200 GeV p +p and Central Au +Au Collisions

    Science.gov (United States)

    Adamczyk, L.; Adkins, J. K.; Agakishiev, G.; Aggarwal, M. M.; Ahammed, Z.; Alekseev, I.; Alford, J.; Anson, C. D.; Aparin, A.; Arkhipkin, D.; Aschenauer, E. C.; Averichev, G. S.; Banerjee, A.; Beavis, D. R.; Bellwied, R.; Bhasin, A.; Bhati, A. K.; Bhattarai, P.; Bichsel, H.; Bielcik, J.; Bielcikova, J.; Bland, L. C.; Bordyuzhin, I. G.; Borowski, W.; Bouchet, J.; Brandin, A. V.; Brovko, S. G.; Bültmann, S.; Bunzarov, I.; Burton, T. P.; Butterworth, J.; Caines, H.; Calderón de la Barca Sánchez, M.; Cebra, D.; Cendejas, R.; Cervantes, M. C.; Chaloupka, P.; Chang, Z.; Chattopadhyay, S.; Chen, H. F.; Chen, J. H.; Chen, L.; Cheng, J.; Cherney, M.; Chikanian, A.; Christie, W.; Chwastowski, J.; Codrington, M. J. M.; Contin, G.; Cramer, J. G.; Crawford, H. J.; Cui, X.; Das, S.; Davila Leyva, A.; De Silva, L. C.; Debbe, R. R.; Dedovich, T. G.; Deng, J.; Derevschikov, A. A.; Derradi de Souza, R.; Dhamija, S.; di Ruzza, B.; Didenko, L.; Dilks, C.; Ding, F.; Djawotho, P.; Dong, X.; Drachenberg, J. L.; Draper, J. E.; Du, C. M.; Dunkelberger, L. E.; Dunlop, J. C.; Efimov, L. G.; Engelage, J.; Engle, K. S.; Eppley, G.; Eun, L.; Evdokimov, O.; Eyser, O.; Fatemi, R.; Fazio, S.; Fedorisin, J.; Filip, P.; Finch, E.; Fisyak, Y.; Flores, C. E.; Gagliardi, C. A.; Gangadharan, D. R.; Garand, D.; Geurts, F.; Gibson, A.; Girard, M.; Gliske, S.; Greiner, L.; Grosnick, D.; Gunarathne, D. S.; Guo, Y.; Gupta, A.; Gupta, S.; Guryn, W.; Haag, B.; Hamed, A.; Han, L.-X.; Haque, R.; Harris, J. W.; Heppelmann, S.; Hirsch, A.; Hoffmann, G. W.; Hofman, D. J.; Horvat, S.; Huang, B.; Huang, H. Z.; Huang, X.; Huck, P.; Humanic, T. J.; Igo, G.; Jacobs, W. W.; Jang, H.; Judd, E. G.; Kabana, S.; Kalinkin, D.; Kang, K.; Kauder, K.; Ke, H. W.; Keane, D.; Kechechyan, A.; Kesich, A.; Khan, Z. H.; Kikola, D. P.; Kisel, I.; Kisiel, A.; Koetke, D. D.; Kollegger, T.; Konzer, J.; Koralt, I.; Kotchenda, L.; Kraishan, A. F.; Kravtsov, P.; Krueger, K.; Kulakov, I.; Kumar, L.; Kycia, R. A.; Lamont, M. A. C.; Landgraf, J. M.; Landry, K. D.; Lauret, J.; Lebedev, A.; Lednicky, R.; Lee, J. H.; LeVine, M. J.; Li, C.; Li, W.; Li, X.; Li, X.; Li, Y.; Li, Z. M.; Lisa, M. A.; Liu, F.; Ljubicic, T.; Llope, W. J.; Lomnitz, M.; Longacre, R. S.; Luo, X.; Ma, G. L.; Ma, Y. G.; Madagodagettige Don, D. M. M. D.; Mahapatra, D. P.; Majka, R.; Margetis, S.; Markert, C.; Masui, H.; Matis, H. S.; McDonald, D.; McShane, T. S.; Minaev, N. G.; Mioduszewski, S.; Mohanty, B.; Mondal, M. M.; Morozov, D. A.; Mustafa, M. K.; Nandi, B. K.; Nasim, Md.; Nayak, T. K.; Nelson, J. M.; Nigmatkulov, G.; Nogach, L. V.; Noh, S. Y.; Novak, J.; Nurushev, S. B.; Odyniec, G.; Ogawa, A.; Oh, K.; Ohlson, A.; Okorokov, V.; Oldag, E. W.; Olvitt, D. L., Jr.; Pachr, M.; Page, B. S.; Pal, S. K.; Pan, Y. X.; Pandit, Y.; Panebratsev, Y.; Pawlak, T.; Pawlik, B.; Pei, H.; Perkins, C.; Peryt, W.; Pile, P.; Planinic, M.; Pluta, J.; Poljak, N.; Porter, J.; Poskanzer, A. M.; Pruthi, N. K.; Przybycien, M.; Pujahari, P. R.; Putschke, J.; Qiu, H.; Quintero, A.; Ramachandran, S.; Raniwala, R.; Raniwala, S.; Ray, R. L.; Riley, C. K.; Ritter, H. G.; Roberts, J. B.; Rogachevskiy, O. V.; Romero, J. L.; Ross, J. F.; Roy, A.; Ruan, L.; Rusnak, J.; Rusnakova, O.; Sahoo, N. R.; Sahu, P. K.; Sakrejda, I.; Salur, S.; Sandweiss, J.; Sangaline, E.; Sarkar, A.; Schambach, J.; Scharenberg, R. P.; Schmah, A. M.; Schmidke, W. B.; Schmitz, N.; Seger, J.; Seyboth, P.; Shah, N.; Shahaliev, E.; Shanmuganathan, P. V.; Shao, M.; Sharma, B.; Shen, W. Q.; Shi, S. S.; Shou, Q. Y.; Sichtermann, E. P.; Singaraju, R. N.; Skoby, M. J.; Smirnov, D.; Smirnov, N.; Solanki, D.; Sorensen, P.; Spinka, H. M.; Srivastava, B.; Stanislaus, T. D. S.; Stevens, J. R.; Stock, R.; Strikhanov, M.; Stringfellow, B.; Sumbera, M.; Sun, X.; Sun, X. M.; Sun, Y.; Sun, Z.; Surrow, B.; Svirida, D. N.; Symons, T. J. M.; Szelezniak, M. A.; Takahashi, J.; Tang, A. H.; Tang, Z.; Tarnowsky, T.; Thomas, J. H.; Timmins, A. R.; Tlusty, D.; Tokarev, M.; Trentalange, S.; Tribble, R. E.; Tribedy, P.; Trzeciak, B. A.; Tsai, O. D.; Turnau, J.; Ullrich, T.; Underwood, D. G.; Van Buren, G.; van Nieuwenhuizen, G.; Vandenbroucke, M.; Vanfossen, J. A.; Varma, R.; Vasconcelos, G. M. S.; Vasiliev, A. N.; Vertesi, R.; Videbæk, F.; Viyogi, Y. P.; Vokal, S.; Vossen, A.; Wada, M.; Wang, F.; Wang, G.; Wang, H.; Wang, J. S.; Wang, X. L.; Wang, Y.; Wang, Y.; Webb, G.; Webb, J. C.; Westfall, G. D.; Wieman, H.; Wissink, S. W.; Witt, R.; Wu, Y. F.; Xiao, Z.; Xie, W.; Xin, K.; Xu, H.; Xu, J.; Xu, N.; Xu, Q. H.; Xu, Y.; Xu, Z.; Yan, W.; Yang, C.; Yang, Y.; Yang, Y.; Ye, Z.; Yepes, P.; Yi, L.; Yip, K.; Yoo, I.-K.; Yu, N.; Zawisza, Y.; Zbroszczyk, H.; Zha, W.; Zhang, J. B.; Zhang, J. L.; Zhang, S.; Zhang, X. P.; Zhang, Y.; Zhang, Z. P.; Zhao, F.; Zhao, J.; Zhong, C.; Zhu, X.; Zhu, Y. H.; Zoulkarneeva, Y.; Zyzak, M.; STAR Collaboration

    2014-03-01

    Azimuthal angular correlations of charged hadrons with respect to the axis of a reconstructed (trigger) jet in Au +Au and p +p collisions at √sNN =200 GeV in STAR are presented. The trigger jet population in Au +Au collisions is biased toward jets that have not interacted with the medium, allowing easier matching of jet energies between Au +Au and p +p collisions while enhancing medium effects on the recoil jet. The associated hadron yield of the recoil jet is significantly suppressed at high transverse momentum (pTassoc) and enhanced at low pTassoc in 0%-20% central Au +Au collisions compared to p +p collisions, which is indicative of medium-induced parton energy loss in ultrarelativistic heavy-ion collisions.

  15. Manipulating the kinetics of seeded growth for edge-selective metal deposition and the formation of concave au nanocrystals.

    Science.gov (United States)

    Laskar, Moitree; Zhong, Xiaolan; Li, Zhi-Yuan; Skrabalak, Sara E

    2013-10-01

    By manipulating the kinetics of seeded growth through judicious control of reaction conditions, edge-selective metal deposition can be achieved to synthesize new Au nanostructures with face-centered concavities, referred to herein as Au overgrown trisoctahedra. These nanostructures display higher sensitivity to changes in refractive index compared to both Au traditional trisoctahedra and the Au nanocube seeds from which they are grown. Often, concave nanostructures are achieved by selective etching processes or corner-selective overgrowth and adopt a stellated profile rather than a profile with face-centered concavities. The presented results illustrate another strategy toward concave nanostructures and can facilitate the synthesis of new concave nanostructures for applications in catalysis and chemical sensing. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  16. Adaptation aux effets qu'ont les changements climatiques sur les ...

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

    Le projet a pour objectif général d'appuyer la capacité d'adaptation aux effets que les changements climatiques ont sur les ressources en eau au Canada, ... de transfert et d'application des connaissances ayant trait à la salubrité du climat et à la gestion des risques que les changements climatiques présentent pour la ...

  17. Role of work function in field emission enhancement of Au island decorated vertically aligned ZnO nanotapers

    Energy Technology Data Exchange (ETDEWEB)

    Singh, Avanendra [School of Physical Sciences, National Institute of Science Education and Research (NISER), HBNI, Bhubaneswar 752050, Odisha (India); Senapati, Kartik, E-mail: kartik@niser.ac.in [School of Physical Sciences, National Institute of Science Education and Research (NISER), HBNI, Bhubaneswar 752050, Odisha (India); Kumar, Mohit; Som, Tapobrata [SUNAG Laboratory, Institute of Physics, Bhubaneswar 751005, Odisha (India); Sinha, Anil K. [Indus Synchrotrons Utilization Division, Raja Ramanna Centre for Advanced Technology, Indore 452013, M.P. (India); Sahoo, Pratap K., E-mail: pratap.sahoo@niser.ac.in [School of Physical Sciences, National Institute of Science Education and Research (NISER), HBNI, Bhubaneswar 752050, Odisha (India)

    2017-07-31

    Highlights: • Hydrothermally synthesized nanotapers were decorated by gold corrugation using simple evaporation techniques for large area applications. • A significantly enhanced field emission properties of nanotapers were achieved. • The metal induced midgap states formed at the ZnO-Au interface and the reduced effective work function are responsible for low turn-on field. • TUNA measurements revealed a very uniform spatial emission profile in the Au decorated nanotapers. - Abstract: In this report, we demonstrate significantly enhanced field emission properties of ZnO nanotapers achieved via a corrugated decoration of Au. Field emission experiments on these Au-decorated ZnO nanotapers showed emission current densities comparable to the best results in the literature. Au decoration of 5 nm also reduced the effective turn-on field to ∼0.54 V/μm, compared to the as grown ZnO nanotapers, which showed a turn-on field of ∼1.1 V/μm. Tunneling atomic force microscopy measurements revealed a very uniform spatial emission profile in the 5 nm Au decorated nanotapers, which is a basic requirement for any large scale application. We believe that metal induced mid-gap states formed at the ZnO–Au interface are responsible for the observed low turn-on field because such interface states are known to reduce the effective work function. A direct measurement of effective work function using Kelvin probe force microscopy indeed showed more than 1.1 eV drop in the case of 5 nm Au decorated ZnO nanotapers compared to the pristine nanotapers, supporting the above argument.

  18. In-situ STM study of phosphate adsorption on Cu(111), Au(111) and Cu/Au(111) electrodes

    DEFF Research Database (Denmark)

    Schlaup, Christian; Horch, Sebastian

    2013-01-01

    The interaction of Cu(111), Au(111) and Cu-covered Au(111) electrodes with a neutral phosphate buffer solution has been studied by means of cyclic voltammetry (CV) and in situ electrochemical scanning tunneling microscopy (EC-STM). Under low potential conditions, both the Cu(111) and the Au(111...

  19. Di-hadron correlations with identified leading hadrons in 200 GeV Au + Au and d + Au collisions at STAR

    Energy Technology Data Exchange (ETDEWEB)

    Adamczyk, L; Adkins, JK; Agakishiev, G; Aggarwal, MM; Ahammed, Z; Alekseev, I; Aparin, A; Arkhipkin, D; Aschenauer, EC; Averichev, GS; Bai, X; Bairathi, V; Banerjee, A; Bellwied, R; Bhasin, A; Bhati, AK; Bhattarai, P; Bielcik, J; Bielcikova, J; Bland, LC; Bordyuzhin, IG; Bouchet, J; Brandenburg, D; Brandin, AV; Bunzarov, I; Butterworth, J; Caines, H; Calderón de la Barca Sánchez, M; Campbell, JM; Cebra, D; Cervantes, MC; Chakaberia, I; Chaloupka, P; Chang, Z; Chattopadhyay, S; Chen, X; Chen, JH; Cheng, J; Cherney, M; Christie, W; Contin, G; Crawford, HJ; Das, S; De Silva, LC; Debbe, RR; Dedovich, TG; Deng, J; Derevschikov, AA; di Ruzza, B; Didenko, L; Dilks, C; Dong, X; Drachenberg, JL; Draper, JE; Du, CM; Dunkelberger, LE; Dunlop, JC; Efimov, LG; Engelage, J; Eppley, G; Esha, R; Evdokimov, O; Eyser, O; Fatemi, R; Fazio, S; Federic, P; Fedorisin, J; Feng, Z; Filip, P; Fisyak, Y; Flores, CE; Fulek, L; Gagliardi, CA; Garand, D; Geurts, F; Gibson, A; Girard, M; Greiner, L; Grosnick, D; Gunarathne, DS; Guo, Y; Gupta, S; Gupta, A; Guryn, W; Hamad, A; Hamed, A; Haque, R; Harris, JW; He, L; Heppelmann, S; Heppelmann, S; Hirsch, A; Hoffmann, GW; Hofman, DJ; Horvat, S; Huang, T; Huang, B; Huang, HZ; Huang, X; Huck, P

    2015-10-23

    The STAR Collaboration presents for the first time two-dimensional di-hadron correlations with identified leading hadrons in 200 GeV central Au + Au and minimum-bias d + Au collisions to explore hadronization mechanisms in the quark gluon plasma. The enhancement of the jet-like yield for leading pions in Au + Au data with respect to the d + Au reference and the absence of such an enhancement for leading non-pions (protons and kaons) are discussed within the context of a quark recombination scenario. The correlated yield at large angles, specifically in the ridge region, is found to be significantly higher for leading non-pions than pions. The consistencies of the constituent quark scaling, azimuthal harmonic model and a mini-jet modification model description of the data are tested, providing further constraints on hadronization.

  20. Di-hadron correlations with identified leading hadrons in 200 GeV Au+Au and d+Au collisions at STAR

    Directory of Open Access Journals (Sweden)

    L. Adamczyk

    2015-12-01

    Full Text Available The STAR Collaboration presents for the first time two-dimensional di-hadron correlations with identified leading hadrons in 200 GeV central Au+Au and minimum-bias d+Au collisions to explore hadronization mechanisms in the quark gluon plasma. The enhancement of the jet-like yield for leading pions in Au+Au data with respect to the d+Au reference and the absence of such an enhancement for leading non-pions (protons and kaons are discussed within the context of a quark recombination scenario. The correlated yield at large angles, specifically in the ridge region, is found to be significantly higher for leading non-pions than pions. The consistencies of the constituent quark scaling, azimuthal harmonic model and a mini-jet modification model description of the data are tested, providing further constraints on hadronization.

  1. Di-hadron correlations with identified leading hadrons in 200 GeV Au + Au and d + Au collisions at STAR

    Science.gov (United States)

    Adamczyk, L.; Adkins, J. K.; Agakishiev, G.; Aggarwal, M. M.; Ahammed, Z.; Alekseev, I.; Aparin, A.; Arkhipkin, D.; Aschenauer, E. C.; Averichev, G. S.; Bai, X.; Bairathi, V.; Banerjee, A.; Bellwied, R.; Bhasin, A.; Bhati, A. K.; Bhattarai, P.; Bielcik, J.; Bielcikova, J.; Bland, L. C.; Bordyuzhin, I. G.; Bouchet, J.; Brandenburg, D.; Brandin, A. V.; Bunzarov, I.; Butterworth, J.; Caines, H.; Calderón de la Barca Sánchez, M.; Campbell, J. M.; Cebra, D.; Cervantes, M. C.; Chakaberia, I.; Chaloupka, P.; Chang, Z.; Chattopadhyay, S.; Chen, X.; Chen, J. H.; Cheng, J.; Cherney, M.; Christie, W.; Contin, G.; Crawford, H. J.; Das, S.; De Silva, L. C.; Debbe, R. R.; Dedovich, T. G.; Deng, J.; Derevschikov, A. A.; di Ruzza, B.; Didenko, L.; Dilks, C.; Dong, X.; Drachenberg, J. L.; Draper, J. E.; Du, C. M.; Dunkelberger, L. E.; Dunlop, J. C.; Efimov, L. G.; Engelage, J.; Eppley, G.; Esha, R.; Evdokimov, O.; Eyser, O.; Fatemi, R.; Fazio, S.; Federic, P.; Fedorisin, J.; Feng, Z.; Filip, P.; Fisyak, Y.; Flores, C. E.; Fulek, L.; Gagliardi, C. A.; Garand, D.; Geurts, F.; Gibson, A.; Girard, M.; Greiner, L.; Grosnick, D.; Gunarathne, D. S.; Guo, Y.; Gupta, S.; Gupta, A.; Guryn, W.; Hamad, A.; Hamed, A.; Haque, R.; Harris, J. W.; He, L.; Heppelmann, S.; Heppelmann, S.; Hirsch, A.; Hoffmann, G. W.; Hofman, D. J.; Horvat, S.; Huang, T.; Huang, B.; Huang, H. Z.; Huang, X.; Huck, P.; Humanic, T. J.; Igo, G.; Jacobs, W. W.; Jang, H.; Jia, J.; Jiang, K.; Judd, E. G.; Kabana, S.; Kalinkin, D.; Kang, K.; Kauder, K.; Ke, H. W.; Keane, D.; Kechechyan, A.; Khan, Z. H.; Kikoła, D. P.; Kisiel, A.; Kochenda, L.; Koetke, D. D.; Kosarzewski, L. K.; Kraishan, A. F.; Kravtsov, P.; Krueger, K.; Kumar, L.; Lamont, M. A. C.; Landgraf, J. M.; Landry, K. D.; Lauret, J.; Lebedev, A.; Lednicky, R.; Lee, J. H.; Li, X.; Li, W.; Li, Z. M.; Li, Y.; Li, C.; Li, X.; Lisa, M. A.; Liu, F.; Ljubicic, T.; Llope, W. J.; Lomnitz, M.; Longacre, R. S.; Luo, X.; Ma, G. L.; Ma, Y. G.; Ma, R.; Ma, L.; Magdy, N.; Majka, R.; Manion, A.; Margetis, S.; Markert, C.; Masui, H.; Matis, H. S.; McDonald, D.; Meehan, K.; Mei, J. C.; Minaev, N. G.; Mioduszewski, S.; Mishra, D.; Mohanty, B.; Mondal, M. M.; Morozov, D. A.; Mustafa, M. K.; Nandi, B. K.; Nasim, Md.; Nayak, T. K.; Nigmatkulov, G.; Niida, T.; Nogach, L. V.; Noh, S. Y.; Novak, J.; Nurushev, S. B.; Odyniec, G.; Ogawa, A.; Oh, K.; Okorokov, V.; Olvitt, D.; Page, B. S.; Pak, R.; Pan, Y. X.; Pandit, Y.; Panebratsev, Y.; Pawlik, B.; Pei, H.; Perkins, C.; Peterson, A.; Pile, P.; Pluta, J.; Poniatowska, K.; Porter, J.; Posik, M.; Poskanzer, A. M.; Pruthi, N. K.; Putschke, J.; Qiu, H.; Quintero, A.; Ramachandran, S.; Raniwala, R.; Raniwala, S.; Ray, R. L.; Ritter, H. G.; Roberts, J. B.; Rogachevskiy, O. V.; Romero, J. L.; Roy, A.; Ruan, L.; Rusnak, J.; Rusnakova, O.; Sahoo, N. R.; Sahu, P. K.; Sakrejda, I.; Salur, S.; Sandweiss, J.; Sarkar, A.; Schambach, J.; Scharenberg, R. P.; Schmah, A. M.; Schmidke, W. B.; Schmitz, N.; Seger, J.; Seyboth, P.; Shah, N.; Shahaliev, E.; Shanmuganathan, P. V.; Shao, M.; Sharma, B.; Sharma, M. K.; Shen, W. Q.; Shi, S. S.; Shou, Q. Y.; Sichtermann, E. P.; Sikora, R.; Simko, M.; Singha, S.; Skoby, M. J.; Smirnov, N.; Smirnov, D.; Song, L.; Sorensen, P.; Spinka, H. M.; Srivastava, B.; Stanislaus, T. D. S.; Stepanov, M.; Strikhanov, M.; Stringfellow, B.; Sumbera, M.; Summa, B.; Sun, Y.; Sun, Z.; Sun, X. M.; Sun, X.; Surrow, B.; Svirida, D. N.; Szelezniak, M. A.; Tang, A. H.; Tang, Z.; Tarnowsky, T.; Tawfik, A.; Thomas, J. H.; Timmins, A. R.; Tlusty, D.; Todoroki, T.; Tokarev, M.; Trentalange, S.; Tribble, R. E.; Tribedy, P.; Tripathy, S. K.; Tsai, O. D.; Ullrich, T.; Underwood, D. G.; Upsal, I.; Van Buren, G.; van Nieuwenhuizen, G.; Vandenbroucke, M.; Varma, R.; Vasiliev, A. N.; Vertesi, R.; Videbæk, F.; Viyogi, Y. P.; Vokal, S.; Voloshin, S. A.; Vossen, A.; Wang, J. S.; Wang, F.; Wang, H.; Wang, G.; Wang, Y.; Wang, Y.; Webb, G.; Webb, J. C.; Wen, L.; Westfall, G. D.; Wieman, H.; Wissink, S. W.; Witt, R.; Wu, Y. F.; Wu; Xiao, Z. G.; Xie, W.; Xin, K.; Xu, H.; Xu, Z.; Xu, Q. H.; Xu, Y. F.; Xu, N.; Yang, S.; Yang, Y.; Yang, Q.; Yang, Y.; Yang, C.; Yang, Y.; Ye, Z.; Ye, Z.; Yepes, P.; Yi, L.; Yip, K.; Yoo, I.-K.; Yu, N.; Zbroszczyk, H.; Zha, W.; Zhang, Y.; Zhang, Z.; Zhang, J. B.; Zhang, J.; Zhang, X. P.; Zhang, S.; Zhang, J.; Zhao, J.; Zhong, C.; Zhou, L.; Zhu, X.; Zoulkarneeva, Y.

    2015-12-01

    The STAR Collaboration presents for the first time two-dimensional di-hadron correlations with identified leading hadrons in 200 GeV central Au + Au and minimum-bias d + Au collisions to explore hadronization mechanisms in the quark gluon plasma. The enhancement of the jet-like yield for leading pions in Au + Au data with respect to the d + Au reference and the absence of such an enhancement for leading non-pions (protons and kaons) are discussed within the context of a quark recombination scenario. The correlated yield at large angles, specifically in the ridge region, is found to be significantly higher for leading non-pions than pions. The consistencies of the constituent quark scaling, azimuthal harmonic model and a mini-jet modification model description of the data are tested, providing further constraints on hadronization.

  2. "Dealloying" Phase Separation during Growth of Au on Ni(110)

    DEFF Research Database (Denmark)

    Nielsen, L. Pleth; Besenbacher, Flemming; Stensgaard, I.

    1995-01-01

    Combined scanning tunneling microscopy and ion-scattering studies have revealed a new "dealloying" phase transition during the growth of Au on Ni(110). The Au atoms, which initially alloy into the Ni(110) surface, phase separate into a vacancy-stabilized Au dimer-trimer chain structure at Au...... coverages larger than 0.4 monolayer. Using the effective-medium theory, we show that the resulting structure as well as the physical mechanism responsible for the phase transition are closely related to the surface stress induced by the substituted Au....

  3. [Hyp-Au-Sn9(Hyp)3-Au-Sn9(Hyp)3-Au-Hyp]-: the longest intermetalloid chain compound of tin.

    Science.gov (United States)

    Binder, Mareike; Schrenk, Claudio; Block, Theresa; Pöttgen, Rainer; Schnepf, Andreas

    2017-10-12

    The reaction of the metalloid tin cluster [Sn 10 (Hyp) 4 ] 2- with (Ph 3 P)Au-SHyp (Hyp = Si(SiMe 3 ) 3 ) gave an intermetalloid cluster [Au 3 Sn 18 (Hyp) 8 ] - 1, which is the longest intermetalloid chain compound of tin to date. 1 shows a structural resemblance to binary AuSn phases, which is expected for intermetalloid clusters.

  4. Preliminary investigations on the preparation of gold nanoparticles intrinsically radiolabeled with 199Au

    International Nuclear Information System (INIS)

    Vimalnath, K.V.; Chakraborty, Sudipta; Dash, Ashutosh

    2016-01-01

    Radiolabeled nanoparticles are of great interest in the current perspective of the nuclear medicine. Water dispersible materials with nanoscale dimensions are finding role in biomedical application owing to their size. These particles can access otherwise unreachable regions in tumor mainly due to Enhanced Permeability and Retention (EPR) effect. Nanoparticles of gold (AuNPs) can bind to a wide range of biologically active molecules with functional groups that have high affinity for the gold surface. Sulfur containing compounds (e.g. thiols, disulfides), organic phosphates, amines, PEG, etc. are some of the well known surface modifiers. Functional thiolates, oligonucleotides, peptides and PEGs are introduced upon subsequent bimolecular substitution of a ligand by a functional thiol easily attached to AuNPs. Owing to its favourable decay characteristics 199 Au (T 1/2 = 3.15 d, E âmax = 474 keV, Eg 158.4 keV (36.9 %) and 208.2 keV (8.4 %)) is an attractive radionuclide for theragnostic applications. In the present work, we have carried out preliminary radiochemical investigations on the preparation of gold nanoparticles intrinsically radiolabeled with 199 Au for its potential utility as a theragnostic agent targeted delivery to the tumors

  5. Sens au travail et management du travail

    OpenAIRE

    Frémeaux, Sandrine

    2014-01-01

    Se définissant comme une activité qui a un but (Brief et Nord, 1990), le travail répond au besoin humain de donner sens (Maslow, 1964). D’un côté, les sujets cherchent davantage aujourd’hui à donner sens à leur travail (Clot, 2008), celui-ci devenant l’objet d’une demande nouvelle de réalisation de soi. D’un autre côté, les entreprises tendent à se focaliser sur les évolutions externes liées à la financiarisation de l’économie et à la mondialisation et à perdre de vue le sens au travail. Et m...

  6. Inverse method for effects characterization from ultrasonic b-scan images; Caracterisation des defauts par une methode d'inversion lors d'un controle ultrasonore. Application au controle des defauts en paroi externe

    Energy Technology Data Exchange (ETDEWEB)

    Faur, M. [Paris-11 Univ., 91 - Orsay (France)

    1999-02-01

    In service inspections of French nuclear pressure water reactor vessels are carried out automatically in complete immersion from the inside by means of ultrasonic focused probes working in the pulse echo mode. Concern has been expressed about the capabilities of performing non destructive evaluation of the Outer Surface Defects (OSD), i.e. defects located in the vicinity of the outer surface of the inspected components. OSD are insonified by both a direct field that passes through the inner surface (water/steel) of the component containing the defect and a secondary field reflected from the outer surface. Consequently, the Bscan images, containing the signatures of such defects, are complicated and their interpretation is a difficult task. This work deals with extraction of the maximum available information for characterizing OSD from ultrasonic Bscan images. Our main objectives are to obtain the type of OSD and their geometric parameters by means of two specific inverse methods. The first method is used for the identification of the geometrical parameters of the equivalent planar OSD from segmented Bscan images. Ultrasonic equivalent defect sizing model-based methods may be used to size a defect in a material by obtaining a best-fit simple equivalent shape that matches the ultrasonic observed data. We illustrate the application of such an equivalent sizing OSD method that is based on a simplified direct model. The major drawback of this identification method, as used to date, is that only a part of the useful information contained into original Bscan image, i.e. segmented Bscan image, is used for defect characterization. Moreover, it requires the availability of defect classification information (i.e. if the defect is volumetric or planer, e. g. a crack or a lack of fusion), which, generally, may be as difficult to obtain as the defect parameters themselves. Therefore, we propose a parameter estimation method for extracting complementary information on the defect

  7. Anomalies hematologiques au cours des accidents vasculaires ...

    African Journals Online (AJOL)

    Introduction: En Côte d'Ivoire, les accidents vasculaires cérébraux (AVC) sont de plus en plus fréquents. Les anomalies biochimiques sont décrites au cours de ces pathologies. Cependant une composante hématologique est de plus en plus évoquée. L'objectif de cette étude a été de rapporter les anomalies ...

  8. Le CRDI au Népal

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

    Les chercheurs ont aidé les agriculteurs de Kulekhani à adopter la pisciculture en cage. CRDI. Centre De reCherChes pour le Développement internAtionAl. Le CRDI au Népal. Grâce à l'appui du CRDI. □ les collectivités s'adaptent aux changements climatiques. □ les agriculteurs de l'Himalaya améliorent leurs moyens.

  9. La cardiomyopathie dilatee au centre hospitalier Universitaire ...

    African Journals Online (AJOL)

    But : Afin d'améliorer la prise en charge, d'éviter l'évolution rapide vers une insuffisance cardiaque réfractaire au traitement, nous avons entrepris cette étude en milieu hospitalier. Méthode : il s'est agi d'une étude rétrospective et descriptive dans le service de cardiologie du Centre Hospitalier Universitaire Tokoin de Lomé.

  10. Synthesis of Pd-Au bimetallic nanocrystals via controlled overgrowth.

    Science.gov (United States)

    Lim, Byungkwon; Kobayashi, Hirokazu; Yu, Taekyung; Wang, Jinguo; Kim, Moon J; Li, Zhi-Yuan; Rycenga, Matthew; Xia, Younan

    2010-03-03

    This paper describes the synthesis of Pd-Au bimetallic nanocrystals with controlled morphologies via a one-step seeded-growth method. Two different reducing agents, namely, L-ascorbic acid and citric acid, were utilized for the reduction of HAuCl(4) in an aqueous solution to control the overgrowth of Au on cubic Pd seeds. When L-ascorbic acid was used as the reducing agent, conformal overgrowth of Au on the Pd nanocubes led to the formation of Pd-Au nanocrystals with a core-shell structure. On the contrary, localized overgrowth of Au was observed when citric acid was used as the reducing agent, producing Pd-Au bimetallic dimers. Through this morphological control, we were able to tune the localized surface plasmon resonance peaks of Pd-Au bimetallic nanostructures in the visible region.

  11. Au-nanoparticles grafted on plasma treated PE

    International Nuclear Information System (INIS)

    Svorcik, V.; Chaloupka, A.; Rezanka, P.; Slepicka, P.; Kolska, Z.; Kasalkova, N.; Hubacek, T.; Siegel, J.

    2010-01-01

    Polyethylene (PE) surface was treated with Ar plasma. Activated surface was grafted from methanol solution of 1,2-ethanedithiol. Then the sample was immersed into freshly prepared colloid solution of Au-nanoparticles. Finally Au layer was sputtered on the samples. Properties of the modified PE were studied using various methods: AFM, EPR, RBS and nanoindentation. It was shown that the plasma treatment results in degradation of polymer chain (AFM) and creation of free radicals by EPR. After grafting with dithiol, the concentration of free radicals declines. The presence of Au and S in the surface layer after the coating with Au-nanoparticles was proved by RBS. Plasma treatment changes PE surface morphology and increases surface roughness, too. Another significant change in surface morphology and roughness was observed after deposition of Au-nanoparticles. Nanoindentation measurements show that the grafting with Au-nanoparticles increases adhesion of subsequently sputtered Au layer.

  12. Active AU Based Patch Weighting for Facial Expression Recognition

    Directory of Open Access Journals (Sweden)

    Weicheng Xie

    2017-01-01

    Full Text Available Facial expression has many applications in human-computer interaction. Although feature extraction and selection have been well studied, the specificity of each expression variation is not fully explored in state-of-the-art works. In this work, the problem of multiclass expression recognition is converted into triplet-wise expression recognition. For each expression triplet, a new feature optimization model based on action unit (AU weighting and patch weight optimization is proposed to represent the specificity of the expression triplet. The sparse representation-based approach is then proposed to detect the active AUs of the testing sample for better generalization. The algorithm achieved competitive accuracies of 89.67% and 94.09% for the Jaffe and Cohn–Kanade (CK+ databases, respectively. Better cross-database performance has also been observed.

  13. How Ag Nanospheres Are Transformed into AgAu Nanocages

    Energy Technology Data Exchange (ETDEWEB)

    Moreau, Liane M.; Schurman, Charles A.; Kewalramani, Sumit; Shahjamali, Mohammad M.; Mirkin, Chad A.; Bedzyk, Michael J. (NWU)

    2017-08-23

    Bimetallic hollow, porous noble metal nanoparticles are of broad interest for biomedical, optical and catalytic applications. The most straightforward method for preparing such structures involves the reaction between HAuCl4 and well-formed Ag particles, typically spheres, cubes, or triangular prisms, yet the mechanism underlying their formation is poorly understood at the atomic scale. By combining in situ nanoscopic and atomic-scale characterization techniques (XAFS, SAXS, XRF, and electron microscopy) to follow the process, we elucidate a plausible reaction pathway for the conversion of citrate-capped Ag nanospheres to AgAu nanocages; importantly, the hollowing event cannot be explained by the nanoscale Kirkendall effect, nor by Galvanic exchange alone, two processes that have been previously proposed. We propose a modification of the bulk Galvanic exchange process that takes into account considerations that can only occur with nanoscale particles. This nanoscale Galvanic exchange process explains the novel morphological and chemical changes associated with the typically observed hollowing process.

  14. Functionalized Au@Ag-Au nanoparticles as an optical and SERS dual probe for lateral flow sensing.

    Science.gov (United States)

    Bai, Tingting; Wang, Meng; Cao, Min; Zhang, Juan; Zhang, Kangzhen; Zhou, Ping; Liu, Zhengxia; Liu, Ying; Guo, Zhirui; Lu, Xiang

    2018-02-14

    Lateral flow assay strips (LFASs) with Au nanoparticles (NPs) have been widely used as a probe for biomarkers in point-of-care testing; however, there still remain challenges in detection sensitivity and quantitative analysis. In this study, we developed a surface-enhanced Raman scattering (SERS)-based LFAS for quantitative analysis of a biomarker in the low concentration range. Moreover, apart from conventional Au NPs, three other types of citrate-capped Au-Ag bimetallic NPs: Au core with Ag shell NPs (Au@Ag NPs), rattle-like Au core in Ag-Au shell NPs (Au@Ag-Au NPs) and Ag-Au NPs were prepared and functionalized, and their solution-based SERS activities were comprehensively studied by experimental measurement and theoretical analysis. The results clearly indicated that the citrate-capped Au@Ag-Au NPs exhibited the highest SERS activity among the probes tested. Au@Ag-Au NPs were used as both optical and SERS probes in a SERS-based LFAS. In the presence of the analyte at high concentrations, a purple color appeared in the test zone. Highly sensitive and quantitative analysis was realized by measurement of SERS signals from the test lines. One of the most specific markers for cardiac injury, cardiac troponin I (cTnI), was chosen as the detection model. The detection limit of the SERS-based LFAS for cardiac troponin I was 0.09 ng/mL, lowered by nearly 50 times compared with visual results, and could be further lowered by optimization. These results demonstrated that the SERS-based LFAS using citrate-capped Au@Ag-Au NPs as probes can be a powerful tool for highly sensitive and quantitative detection of biomarkers. Graphical abstract A surface-enhanced Raman scattering (SERS)-based lateral flow assay strip using rattle-like Au core in Ag-Au shell (Au@Ag-Au) nanoparticles as probes was developed for quantitative analysis of a biomarker, with a detection limit nearly 50 times lower than that of visual assessment. C control line, T test line.

  15. A photoresponsive Au25 nanocluster protected by azobenzene derivative thiolates

    Science.gov (United States)

    Negishi, Yuichi; Kamimura, Ukyo; Ide, Mao; Hirayama, Michiyo

    2012-06-01

    An Au25 cluster protected by azobenzene derivative thiolates (S-Az) ([Au25(S-Az)18]-) was synthesized with the aim of producing a photoresponsive Au25 cluster. The matrix-assisted laser desorption/ionization mass spectrum of the product revealed that [Au25(S-Az)18]- was synthesized in high purity. Optical absorption spectra of [Au25(S-Az)18]- obtained before and after photoirradiation suggest that the azobenzenes in the ligands of Au25(S-Az)18 isomerize with an efficiency of nearly 100%, both from the trans to cis conformation and from the cis to trans conformation. Furthermore, the redox potential and optical absorption of Au25(S-Az)18 were found to change reversibly due to photoisomerization of azobenzenes.An Au25 cluster protected by azobenzene derivative thiolates (S-Az) ([Au25(S-Az)18]-) was synthesized with the aim of producing a photoresponsive Au25 cluster. The matrix-assisted laser desorption/ionization mass spectrum of the product revealed that [Au25(S-Az)18]- was synthesized in high purity. Optical absorption spectra of [Au25(S-Az)18]- obtained before and after photoirradiation suggest that the azobenzenes in the ligands of Au25(S-Az)18 isomerize with an efficiency of nearly 100%, both from the trans to cis conformation and from the cis to trans conformation. Furthermore, the redox potential and optical absorption of Au25(S-Az)18 were found to change reversibly due to photoisomerization of azobenzenes. Electronic supplementary information (ESI) available: Details of the experimental procedure and characterization of the products. See DOI: 10.1039/c2nr30830d

  16. Engineering Gold Nanorod-Based Plasmonic Nanocrystals for Optical Applications

    KAUST Repository

    Huang, Jianfeng

    2015-09-01

    Plasmonic nanocrystals have a unique ability to support localized surface plasmon resonances and exhibit rich and intriguing optical properties. Engineering plasmonic nanocrystals can maximize their potentials for specific applications. In this dissertation, we developed three unprecedented Au nanorod-based plasmonic nanocrystals through rational design of the crystal shape and/or composition, and successfully demonstrated their applications in light condensation, photothermal conversion, and surface-enhanced Raman spectroscopy (SERS). The “Au nanorod-Au nanosphere dimer” nanocrystal was synthesized via the ligand-induced asymmetric growth of a Au nanosphere on a Au nanorod. This dimeric nanostructure features an extraordinary broadband optical absorption in the range of 400‒1400nm, and it proved to be an ideal black-body material for light condensation and an efficient solar-light harvester for photothermal conversion. The “Au nanorod (core) @ AuAg alloy (shell)” nanocrystal was built through the epitaxial growth of homogeneously alloyed AuAg shells on Au nanorods by precisely controlled synthesis. The resulting core-shell structured, bimetallic nanorods integrate the merits of the AuAg alloy with the advantages of anisotropic nanorods, exhibiting strong, stable and tunable surface plasmon resonances that are essential for SERS applications in a corrosive environment. The “high-index faceted Au nanorod (core) @ AuPd alloy (shell)” nanocrystal was produced via site-specific epitaxial growth of AuPd alloyed horns at the ends of Au nanorods. The AuPd alloyed horns are bound with high-index side facets, while the Au nanorod concentrates an intensive electric field at each end. This unique configuration unites highly active catalytic sites with strong SERS sites into a single entity and was demonstrated to be ideal for in situ monitoring of Pd-catalyzed reactions by SERS. The synthetic strategies developed here are promising towards the fabrication of

  17. A sensitive sandwich-type immunosensor for the detection of galectin-3 based on N-GNRs-Fe-MOFs@AuNPs nanocomposites and a novel AuPt-methylene blue nanorod.

    Science.gov (United States)

    Tang, Zhiyong; He, Junlin; Chen, Jun; Niu, Yazhen; Zhao, Yilin; Zhang, Yuchan; Yu, Chao

    2018-03-15

    We are presenting an electrochemical immunosensor for the determination of Galectin-3 (Gal-3), a biomarker of heart failure. A glassy carbon electrode (GCE) was modified with a film of a composite made from the N-doped graphene nanoribbons immobilized Fe-based-Metal-organic frameworks deposited with Au nanoparticles (N-GNRs-Fe-MOFs@AuNPs). Primary antibody against Gal-3 (Gal-3-Ab 1 ) was immobilized on the Au nanoparticles on the surface of the modified GCE which then was blocked with bovine serum albumin. Signal amplification is crucial for obtaining low detection limits in biosensors. Here, a relatively simple and ultrasensitive sandwich-type electrochemical immunosensor based on novel signal generation and amplification was developed for the determination of Gal-3. A kind of novel redox-active species, AuPt-Methylene blue (MB) (AuPt-MB) nanocomposites, was synthesized by a one-pot method for the first time. Wherein, MB as a kind of the electron transfer mediators in an amperometric biosensor is responsible for electron production and signal amplification. The rod-like AuPt-MB nanohybrids displayed uniform morphology and good electrochemical activity and can combine with the second antibodies against Gal-3 (Gal-3-Ab 2 ). And the AuPt-MB-Ab 2 coupled with the N-GNRs-Fe-MOFs@AuNPs-Ab 1 to form the sandwich type format that can greatly enhance the biosensor's sensitivity. Under optimal conditions, the designed immunosensor exhibited a linear concentration range from 100fgmL -1 to 50ngmL -1 , with a low detection limit of 33.33fgmL -1 (S/N = 3) for Gal-3 in spiked serum. Additionally, the designed immunosensor showed acceptable selectivity, reproducibility and stability. The satisfactory results in analyzing human serum samples indicated potential application promising in monitoring biomarkers. Copyright © 2017 Elsevier B.V. All rights reserved.

  18. Gold nano-particle formation from crystalline AuCN: Comparison of thermal, plasma- and ion-beam activated decomposition

    Energy Technology Data Exchange (ETDEWEB)

    Beck, Mihály T.; Bertóti, Imre, E-mail: bertoti.imre@ttk.mta.hu; Mohai, Miklós; Németh, Péter; Jakab, Emma; Szabó, László; Szépvölgyi, János

    2017-02-15

    In this work, in addition to the conventional thermal process, two non-conventional ways, the plasma and ion beam activations are described for preparing gold nanoparticles from microcrystalline AuCN precursor. The phase formation at plasma and ion beam treatments was compared with that at thermal treatments and the products and transformations were characterized by thermogravimetry-mass-spectrometry (TG-MS), X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM). TG-MS measurements in Ar atmosphere revealed that AuCN decomposition starts at 400 °C and completes at ≈700 °C with evolution of gaseous (CN){sub 2}. XPS and TEM show that in heat treatment at 450 °C for 1 h in Ar, loss of nitrogen and carbon occurs and small, 5–30 nm gold particles forms. Heating at 450 °C for 10 h in sealed ampoule, much larger, 60–200 nm size and well faceted Au particles develop together with a fibrous (CN){sub n} polymer phase, and the Au crystallites are covered by a 3–5 nm thick polymer shell. Low pressure Ar plasma treatment at 300 eV energy results in 4–20 nm size Au particles and removes most of the nitrogen and part of carbon. During Ar{sup +} ion bombardment with 2500 eV energy, 5–30 nm size Au crystallites form already in 10 min, with preferential loss of nitrogen and with increased amount of carbon residue. The results suggest that plasma and ion beam activation, acting similarly to thermal treatment, may be used to prepare Au nanoparticles from AuCN on selected surface areas either by depositing AuCN precursors on selected regions or by focusing the applied ionized radiation. Thus they may offer alternative ways for preparing tailor-made catalysts, electronic devices and sensors for different applications. - Graphical abstract: Proposed scheme of the decomposition mechanism of AuCN samples: heat treatment in Ar flow (a) and in sealed ampoule (b); Ar{sup +} ion treatment at 300 eV (c) and at 2500 eV (d). Cross section sketches

  19. Conductive polymer/reduced graphene oxide/Au nano particles as efficient composite materials in electrochemical supercapacitors

    Energy Technology Data Exchange (ETDEWEB)

    Shabani Shayeh, J. [Center of Excellence in Electrochemistry, University of Tehran, Tehran (Iran, Islamic Republic of); Ehsani, A., E-mail: a.ehsani@qom.ac.ir [Department of Chemistry, Faculty of Science, University of Qom, P.O. Box 37185-359, Qom (Iran, Islamic Republic of); Ganjali, M.R.; Norouzi, P. [Center of Excellence in Electrochemistry, University of Tehran, Tehran (Iran, Islamic Republic of); Endocrinology & Metabolism Research Center, Tehran University of Medical Sciences, Tehran (Iran, Islamic Republic of); Jaleh, B. [Physics Department, Bu-Ali Sina University, Hamedan 65174 (Iran, Islamic Republic of)

    2015-10-30

    Graphical abstract: - Highlights: • PANI/rGO/AuNPs as a ternary composite synthesized by electrodeposition. • Presence of rGO/AuNPs caused increasing the stability of electrodes. • Composite represented high specific capacitance, specific power and specific energy values than PANI. - Abstract: Polyaniline/reduced graphene oxide/Au nano particles (PANI/rGO/AuNPs) as a hybrid supercapacitor were deposited on a glassy carbon electrode (GCE) by cyclic voltammetry (CV) method as ternary composites and their electrochemical performance was evaluated in acidic medium. Scanning electron micrographs clearly revealed the formation of nanocomposites on the surface of the working electrode. Scanning electron micrographs (SEM) clearly revealed the formation of nanocomposites on the surface of working electrode. Different electrochemical methods including galvanostatic charge–discharge (CD) experiments, cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were carried out in order to investigate the applicability of the system as a supercapacitor. Based on the cyclic voltammogram results obtained, PANI/rGO/AuNPs gave higher specific capacitance, power and energy values than PANI at a current density of 1 mA cm{sup −2}. Specific capacitance (SC) of PANI and PANI/rGO/AuNPs electrodes calculated using CV method are 190 and 303 F g{sup −1}, respectively. The present study introduces new nanocomposite materials for electrochemical redox capacitors with advantages including long life cycle and stability due to synergistic effects of each component.

  20. Preparation of Au and Ag nanoparticles using Artemisia annua and their in vitro antibacterial and tyrosinase inhibitory activities

    Energy Technology Data Exchange (ETDEWEB)

    Basavegowda, Nagaraj; Idhayadhulla, Akber; Lee, Yong Rok, E-mail: yrlee@yu.ac.kr

    2014-10-01

    This work describes a plant-mediated approach to the preparation of metal nanoparticles using leaf extract of Artemisia annua (A. annua), an ethno-medicinal plant widely found in Asia, which was used as reducing and stabilizing agent. A. annua is used in traditional Chinese medicine to alleviate fever. Au and Ag nanoparticles were prepared using a one-step aqueous method at room temperature without any toxic chemicals. The formation of Au and Ag nanoparticles was monitored by UV–vis spectroscopy. Synthesized nanoparticles were characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), energy dispersive X-ray analysis (EDX), Fourier transform infrared (FT-IR) spectroscopy, and thermogravimetric analysis (TGA). TEM analysis of Au nanoparticles showed that they had triangular and spherical shapes with sizes ranging from 15 to 40 nm. The silver nanoparticles were predominantly spherical and uniformly sized (30–50 nm). The Au and Ag nanoparticles produced showed significant tyrosinase inhibitory and antibacterial effects. These results suggest that the synthesized nanoparticles provide good alternatives in varied medical and industrial applications. - Highlights: • Au and Ag nanoparticles were synthesized using Artemisia annua leaf aqueous extract. • Nanoparticles were characterized by UV–vis spectroscopy, FT-IR, TEM, EDX, XRD, and TGA. • Au and Ag nanoparticles were of size 25 and 30 nm respectively, in spherical forms. • Nanoparticles showed significant tyrosinase inhibitory and antibacterial activities.

  1. Construction of CuS/Au Heterostructure through a Simple Photoreduction Route for Enhanced Electrochemical Hydrogen Evolution and Photocatalysis

    Science.gov (United States)

    Basu, Mrinmoyee; Nazir, Roshan; Fageria, Pragati; Pande, Surojit

    2016-01-01

    An efficient Hydrogen evolution catalyst has been developed by decorating Au nanoparticle on the surface of CuS nanostructure following a green and environmental friendly approach. CuS nanostructure is synthesized through a simple wet-chemical route. CuS being a visible light photocatalyst is introduced to function as an efficient reducing agent. Photogenerated electron is used to reduce Au(III) on the surface of CuS to prepare CuS/Au heterostructure. The as-obtained heterostructure shows excellent performance in electrochemical H2 evolution reaction with promising durability in acidic condition, which could work as an efficient alternative for novel metals. The most efficient CuS-Au heterostructure can generate 10 mA/cm2 current density upon application of 0.179 V vs. RHE. CuS-Au heterostructure can also perform as an efficient photocatalyst for the degradation of organic pollutant. This dual nature of CuS and CuS/Au both in electrocatalysis and photocatalysis has been unveiled in this study. PMID:27703212

  2. Fabrication and characterizations of ZnO nanorods/Au nanoparticle composites on the electropolished Ti substrate

    Energy Technology Data Exchange (ETDEWEB)

    Chen, Hsiang, E-mail: hchen@ncnu.edu.tw [National Chi Nan University, No.1, Daxue Rd., Puli Township, Nantou County 545, Taiwan, ROC (China); Yeh, Yih-Min [WuFeng University, No. 117, Sec 2, Chiankuo Rd, Minhsiung, Chiayi County 62153, Taiwan, ROC (China); Chen, Jian-Zhi [National Chi Nan University, No.1, Daxue Rd., Puli Township, Nantou County 545, Taiwan, ROC (China); Liu, Song-Ming [WuFeng University, No. 117, Sec 2, Chiankuo Rd, Minhsiung, Chiayi County 62153, Taiwan, ROC (China); Huang, Bo Yun; Wu, Zhi-Huei; Tsai, Shaung-Lin; Chang, Hung-Wei; Chu, Yu-Cheng; Liao, Chuan Hao [National Chi Nan University, No.1, Daxue Rd., Puli Township, Nantou County 545, Taiwan, ROC (China)

    2013-12-31

    Au nanoparticles (NPs) were spread on ZnO nanorods (NRs) on the polished Ti substrate to form Au/ZnO nanocomposites. Multiple material analyses including field emission scanning electron microscopy (FESEM), energy dispersive spectroscopy (EDS), X-ray diffraction (XRD) analyses, Fourier-transform infrared spectrometer (FTIR) and images taken by optical microscope were performed on Au NPs of 2 nm and 20 nm on ZnO NRs. The FESEM and optical images under optical microscope indicate that 20 nm NPs can form more and larger clusters than 2 nm NPs on ZnO nanorod. Furthermore, more Au can be detected by EDS and XRD. We studied the behaviors of Au NPs on ZnO NR applications for future potential biosensing and antiseptic devices. - Highlights: • Nanocomposites of Au nanoparticles were spread on ZnO nanorods on Ti substrate. • Multiple material analyses were performed on 2 nm and 20 nm nanoparticles. • 20 nm nanoparticles formed more and larger clusters. • Optical images show well-distributed nanoparticle ZnO nanorods.

  3. Systematic Study on the Self-Assembled Hexagonal Au Voids, Nano-Clusters and Nanoparticles on GaN (0001.

    Directory of Open Access Journals (Sweden)

    Puran Pandey

    Full Text Available Au nano-clusters and nanoparticles (NPs have been widely utilized in various electronic, optoelectronic, and bio-medical applications due to their great potentials. The size, density and configuration of Au NPs play a vital role in the performance of these devices. In this paper, we present a systematic study on the self-assembled hexagonal Au voids, nano-clusters and NPs fabricated on GaN (0001 by the variation of annealing temperature and deposition amount. At relatively low annealing temperatures between 400 and 600°C, the fabrication of hexagonal shaped Au voids and Au nano-clusters are observed and discussed based on the diffusion limited aggregation model. The size and density of voids and nano-clusters can systematically be controlled. The self-assembled Au NPs are fabricated at comparatively high temperatures from 650 to 800°C based on the Volmer-Weber growth model and also the size and density can be tuned accordingly. The results are symmetrically analyzed and discussed in conjunction with the diffusion theory and thermodynamics by utilizing AFM and SEM images, EDS maps and spectra, FFT power spectra, cross-sectional line-profiles and size and density plots.

  4. Transformation of Ag nanocubes into Ag-Au hollow nanostructures with enriched Ag contents to improve SERS activity and chemical stability.

    Science.gov (United States)

    Yang, Yin; Zhang, Qiang; Fu, Zheng-Wen; Qin, Dong

    2014-03-12

    We report a strategy to complement the galvanic replacement reaction between Ag nanocubes and HAuCl4 with co-reduction by ascorbic acid (AA) for the formation of Ag-Au hollow nanostructures with greatly enhanced SERS activity. Specifically, in the early stage of synthesis, the Ag nanocubes are sharpened at corners and edges because of the selective deposition of Au and Ag atoms at these sites. In the following steps, the pure Ag in the nanocubes is constantly converted into Ag(+) ions to generate voids owing to the galvanic reaction with HAuCl4, but these released Ag(+) ions are immediately reduced back to Ag atoms and are co-deposited with Au atoms onto the nanocube templates. We observe distinctive SERS properties for the Ag-Au hollow nanostructures at visible and near-infrared excitation wavelengths. When plasmon damping is eliminated by using an excitation wavelength of 785 nm, the SERS activity of the Ag-Au hollow nanostructures is 15- and 33-fold stronger than those of the original Ag nanocubes and the Ag-Au nanocages prepared by galvanic replacement without co-reduction, respectively. Additionally, Ag-Au hollow nanostructures embrace considerably improved stability in an oxidizing environment such as aqueous H2O2 solution. Collectively, our work suggests that the Ag-Au hollow nanostructures will find applications in SERS detection and imaging.

  5. Fabrication of Graphene and AuNP Core Polyaniline Shell Nanocomposites as Multifunctional Theranostic Platforms for SERS Real-time Monitoring and Chemo-photothermal Therapy.

    Science.gov (United States)

    Chen, Haolin; Liu, Zhiming; Li, Songyang; Su, Chengkang; Qiu, Xuejun; Zhong, Huiqing; Guo, Zhouyi

    2016-01-01

    In this work, novel theranostic platforms based on graphene oxide and AuNP core polyaniline shell (GO-Au@PANI) nanocomposites are fabricated for simultaneous SERS imaging and chemo-photothermal therapy. PANI, a new NIR photothermal therapy agent with strong NIR absorption, outstanding stability and low cytotoxicity is decorated on AuNPs by one-pot oxidative polymerization, then the Au@PANI core-shell nanoparticles are attached to the graphene oxide (GO) sheet via π-π stacking and electrostatic interaction. The obtained GO-Au@PANI nanohybirds exhibit excellent NIR photothermal transduction efficiency and ultrahigh drug-loading capacity. The nanocomposites can also serve as novel NIR SERS probes utilizing the intense SERS signals of PANI. Rapid SERS imaging of cancer cells is achieved using this ultrasensitive nanoprobe. GO-Au@PANI also reveals good capability of drug delivery with the DOX-loading efficiency of 189.2% and sensitive NIR/pH-responsive DOX release. The intracellular real-time drug release dynamics from the nanocomposites is monitored by SERS-fluorescence dual mode imaging. Finally, chemo-photothermal ablation of cancer cells is carried out in vitro and in vivo using GO-Au@PANI as high-performance chemo-photothermal therapeutic nanoagent. The theranostic applications of GO-Au@PANI endow it with great potential for personalized and precise cancer medicine.

  6. The effect of defects on the catalytic activity of single Au atom supported carbon nanotubes and reaction mechanism for CO oxidation.

    Science.gov (United States)

    Ali, Sajjad; Fu Liu, Tian; Lian, Zan; Li, Bo; Sheng Su, Dang

    2017-08-23

    clear description on the relationship between the defects in the support and the catalytic properties of Au and open a new avenue to develop carbon nanomaterial-based single atom catalysts for application in environmental and energy related fields.

  7. The sandwich-type electrochemiluminescence immunosensor for {alpha}-fetoprotein based on enrichment by Fe{sub 3}O{sub 4}-Au magnetic nano probes and signal amplification by CdS-Au composite nanoparticles labeled anti-AFP

    Energy Technology Data Exchange (ETDEWEB)

    Zhou Hankun [State Key Laboratory Base of Novel Functional Materials and Preparation Science, Faculty of Material Science and Chemical Engineering of Ningbo University, Ningbo 315211 (China); Gan Ning, E-mail: ganning@nbu.edu.cn [State Key Laboratory Base of Novel Functional Materials and Preparation Science, Faculty of Material Science and Chemical Engineering of Ningbo University, Ningbo 315211 (China); Li Tianhua; Cao Yuting; Zeng Saolin [State Key Laboratory Base of Novel Functional Materials and Preparation Science, Faculty of Material Science and Chemical Engineering of Ningbo University, Ningbo 315211 (China); Zheng Lei, E-mail: nfyyzl@163.com [Department of Laboratory Medicine, Nanfang Hospital, Southern Medical University, Guangzhou 510515 (China); Guo Zhiyong [State Key Laboratory Base of Novel Functional Materials and Preparation Science, Faculty of Material Science and Chemical Engineering of Ningbo University, Ningbo 315211 (China)

    2012-10-09

    Highlights: Black-Right-Pointing-Pointer Sandwich immunoreaction, testing a large number of samples simultaneously. Black-Right-Pointing-Pointer The magnetic separation and enrichment by Fe{sub 3}O{sub 4}-Au magnetic nano probes. Black-Right-Pointing-Pointer The amplification of detection signal by CdS-Au composite nanoparticles labeled anti-AFP. Black-Right-Pointing-Pointer Almost no background signal, which greatly improve the sensitivity of detection. - Abstract: A novel and sensitive sandwich-type electrochemiluminescence (ECL) immunosensor was fabricated on a glassy carbon electrode (GCE) for ultra trace levels of {alpha}-fetoprotein (AFP) based on sandwich immunoreaction strategy by enrichment using magnetic capture probes and quantum dots coated with Au shell (CdS-Au) as the signal tag. The capture probe was prepared by immobilizing the primary antibody of AFP (Ab1) on the core/shell Fe{sub 3}O{sub 4}-Au nanoparticles, which was first employed to capture AFP antigens to form Fe{sub 3}O{sub 4}-Au/Ab1/AFP complex from the serum after incubation. The product can be separated from the background solution through the magnetic separation. Then the CdS-Au labeled secondary antibody (Ab2) as signal tag (CdS-Au/Ab2) was conjugated successfully with Fe{sub 3}O{sub 4}-Au/Ab1/AFP complex to form a sandwich-type immunocomplex (Fe{sub 3}O{sub 4}-Au/Ab1/AFP/Ab2/CdS-Au), which can be further separated by an external magnetic field and produce ECL signals at a fixed voltage. The signal was proportional to a certain concentration range of AFP for quantification. Thus, an easy-to-use immunosensor with magnetic probes and a quantum dots signal tag was obtained. The immunosensor performed at a level of high sensitivity and a broad concentration range for AFP between 0.0005 and 5.0 ng mL{sup -1} with a detection limit of 0.2 pg mL{sup -1}. The use of magnetic probes was combined with pre-concentration and separation for trace levels of tumor markers in the serum. Due to the

  8. pH-sensitive Au-BSA-DOX-FA nanocomposites for combined CT imaging and targeted drug delivery.

    Science.gov (United States)

    Huang, He; Yang, Da-Peng; Liu, Minghuan; Wang, Xiangsheng; Zhang, Zhiyong; Zhou, Guangdong; Liu, Wei; Cao, Yilin; Zhang, Wen Jie; Wang, Xiansong

    2017-01-01

    Albumin-based nanoparticles (NPs) as a drug delivery system have attracted much attention owing to their nontoxicity, non-immunogenicity, great stability and ability to bind to many therapeutic drugs. Herein, bovine serum albumin (BSA) was utilized as a template to prepare Au-BSA core/shell NPs. The outer layer BSA was subsequently conjugated with cis -aconityl doxorubicin (DOX) and folic acid (FA) to create Au-BSA-DOX-FA nanocomposites. A list of characterizations was undertaken to identify the successful conjugation of drug molecules and targeted agents. In vitro cytotoxicity using a cell counting kit-8 (CCK-8) assay indicated that Au-BSA NPs did not display obvious cytotoxicity to MGC-803 and GES-1 cells in the concentration range of 0-100 μg/mL, which can therefore be used as a safe drug delivery carrier. Furthermore, compared with free DOX, Au-BSA-DOX-FA nanocomposites exhibited a pH-sensitive drug release ability and superior antitumor activity in a drug concentration-dependent manner. In vivo computed tomography (CT) imaging experiments showed that Au-BSA-DOX-FA nanocomposites could be used as an efficient and durable CT contrast agent for targeted CT imaging of the folate receptor (FR) overexpressed in cancer tissues. In vivo antitumor experiments demonstrated that Au-BSA-DOX-FA nanocomposites have selective antitumor activity effects on FR-overexpressing tumors and no adverse effects on normal tissues and organs. In conclusion, the Au-BSA-DOX-FA nanocomposite exhibits selective targeting activity, X-ray attenuation activity and pH-sensitive drug release activity. Therefore, it can enhance CT imaging and improve the targeting therapeutic efficacy of FR-overexpressing gastric cancers. Our findings suggest that Au-BSA-DOX-FA nanocomposite is a novel drug delivery carrier and a promising candidate for cancer theranostic applications.

  9. CD33 monoclonal antibody conjugated Au cluster nano-bioprobe for targeted flow-cytometric detection of acute myeloid leukaemia

    Energy Technology Data Exchange (ETDEWEB)

    Retnakumari, Archana; Jayasimhan, Jasusri; Chandran, Parwathy; Menon, Deepthy; Nair, Shantikumar; Mony, Ullas; Koyakutty, Manzoor, E-mail: manzoork@aims.amrita.edu, E-mail: ullasmony@aims.amrita.edu [Amrita Centre for Nanoscience and Molecular Medicine, Amrita Institute of Medical Science, Cochin 682 041 (India)

    2011-07-15

    Protein stabilized gold nanoclusters (Au-NCs) are biocompatible, near-infrared (NIR) emitting nanosystems having a wide range of biomedical applications. Here, we report the development of a Au-NC based targeted fluorescent nano-bioprobe for the flow-cytometric detection of acute myeloid leukaemia (AML) cells. Au-NCs with {approx} 25-28 atoms showing bright red-NIR fluorescence (600-750 nm) and average size of {approx} 0.8 nm were prepared by bovine serum albumin assisted reduction-cum-stabilization in aqueous phase. The protein protected clusters were conjugated with monoclonal antibody against CD33 myeloid antigen, which is overexpressed in {approx} 99.2% of the primitive population of AML cells, as confirmed by immunophenotyping using flow cytometry. Au-NC-CD33 conjugates having average size of {approx} 12 nm retained bright fluorescence over an extended duration of {approx} a year, as the albumin protein protects Au-NCs against degradation. Nanotoxicity studies revealed excellent biocompatibility of Au-NC conjugates, as they showed no adverse effect on the cell viability and inflammatory response. Target specificity of the conjugates for detecting CD33 expressing AML cells (KG1a) in flow cytometry showed specific staining of {approx} 95.4% of leukaemia cells within 1-2 h compared to a non-specific uptake of {approx} 8.2% in human peripheral blood cells (PBMCs) which are CD33{sup low}. The confocal imaging also demonstrated the targeted uptake of CD33 conjugated Au-NCs by leukaemia cells, thus confirming the flow cytometry results. This study demonstrates that novel nano-bioprobes can be developed using protein protected fluorescent nanoclusters of Au for the molecular receptor targeted flow cytometry based detection and imaging of cancer cells.

  10. CD33 monoclonal antibody conjugated Au cluster nano-bioprobe for targeted flow-cytometric detection of acute myeloid leukaemia

    Science.gov (United States)

    Retnakumari, Archana; Jayasimhan, Jasusri; Chandran, Parwathy; Menon, Deepthy; Nair, Shantikumar; Mony, Ullas; Koyakutty, Manzoor

    2011-07-01

    Protein stabilized gold nanoclusters (Au-NCs) are biocompatible, near-infrared (NIR) emitting nanosystems having a wide range of biomedical applications. Here, we report the development of a Au-NC based targeted fluorescent nano-bioprobe for the flow-cytometric detection of acute myeloid leukaemia (AML) cells. Au-NCs with ~ 25-28 atoms showing bright red-NIR fluorescence (600-750 nm) and average size of ~ 0.8 nm were prepared by bovine serum albumin assisted reduction-cum-stabilization in aqueous phase. The protein protected clusters were conjugated with monoclonal antibody against CD33 myeloid antigen, which is overexpressed in ~ 99.2% of the primitive population of AML cells, as confirmed by immunophenotyping using flow cytometry. Au-NC-CD33 conjugates having average size of ~ 12 nm retained bright fluorescence over an extended duration of ~ a year, as the albumin protein protects Au-NCs against degradation. Nanotoxicity studies revealed excellent biocompatibility of Au-NC conjugates, as they showed no adverse effect on the cell viability and inflammatory response. Target specificity of the conjugates for detecting CD33 expressing AML cells (KG1a) in flow cytometry showed specific staining of ~ 95.4% of leukaemia cells within 1-2 h compared to a non-specific uptake of ~ 8.2% in human peripheral blood cells (PBMCs) which are CD33low. The confocal imaging also demonstrated the targeted uptake of CD33 conjugated Au-NCs by leukaemia cells, thus confirming the flow cytometry results. This study demonstrates that novel nano-bioprobes can be developed using protein protected fluorescent nanoclusters of Au for the molecular receptor targeted flow cytometry based detection and imaging of cancer cells.

  11. CD33 monoclonal antibody conjugated Au cluster nano-bioprobe for targeted flow-cytometric detection of acute myeloid leukaemia

    International Nuclear Information System (INIS)

    Retnakumari, Archana; Jayasimhan, Jasusri; Chandran, Parwathy; Menon, Deepthy; Nair, Shantikumar; Mony, Ullas; Koyakutty, Manzoor

    2011-01-01

    Protein stabilized gold nanoclusters (Au-NCs) are biocompatible, near-infrared (NIR) emitting nanosystems having a wide range of biomedical applications. Here, we report the development of a Au-NC based targeted fluorescent nano-bioprobe for the flow-cytometric detection of acute myeloid leukaemia (AML) cells. Au-NCs with ∼ 25-28 atoms showing bright red-NIR fluorescence (600-750 nm) and average size of ∼ 0.8 nm were prepared by bovine serum albumin assisted reduction-cum-stabilization in aqueous phase. The protein protected clusters were conjugated with monoclonal antibody against CD33 myeloid antigen, which is overexpressed in ∼ 99.2% of the primitive population of AML cells, as confirmed by immunophenotyping using flow cytometry. Au-NC-CD33 conjugates having average size of ∼ 12 nm retained bright fluorescence over an extended duration of ∼ a year, as the albumin protein protects Au-NCs against degradation. Nanotoxicity studies revealed excellent biocompatibility of Au-NC conjugates, as they showed no adverse effect on the cell viability and inflammatory response. Target specificity of the conjugates for detecting CD33 expressing AML cells (KG1a) in flow cytometry showed specific staining of ∼ 95.4% of leukaemia cells within 1-2 h compared to a non-specific uptake of ∼ 8.2% in human peripheral blood cells (PBMCs) which are CD33 low . The confocal imaging also demonstrated the targeted uptake of CD33 conjugated Au-NCs by leukaemia cells, thus confirming the flow cytometry results. This study demonstrates that novel nano-bioprobes can be developed using protein protected fluorescent nanoclusters of Au for the molecular receptor targeted flow cytometry based detection and imaging of cancer cells.

  12. Mechanistic insights on ethanol dehydrogenation on Pd-Au model catalysts: a combined experimental and DFT study.

    Science.gov (United States)

    Evans, E J; Li, H; Yu, Wen-Yueh; Mullen, G M; Henkelman, G; Mullins, C Buddie

    2017-11-22

    In this study, we have combined ultra-high vacuum (UHV) experiments and density functional theory (DFT) calculations to investigate ethanol (EtOH) dehydrogenation on Pd-Au model catalysts. Using EtOH reactive molecular beam scattering (RMBS), EtOH temperature-programmed desorption (TPD), and DFT calculations, we show how different Pd ensemble sizes on Au(111) can affect the mechanism for EtOH dehydrogenation and H 2 production. The Au(111) surface with an initial coverage of 2 monolayers of Pd (2 ML Pd-Au) had the highest H 2 yield. However, the 1 ML Pd-Au catalyst showed the highest selectivity and stability, yielding appreciable amounts of only H 2 and acetaldehyde. Arrhenius plots of H 2 production confirm that the mechanisms for EtOH dehydrogenation differed between 1 and 2 ML Pd-Au, supporting the perceived difference in selectivity between the two surfaces. DFT calculations support this difference in mechanism, showing a dependence of the initial dehydrogenation selectivity of EtOH on the size of Pd ensemble. DFT binding energies and EtOH TPD confirm that EtOH has increasing surface affinity with increasing Pd ensemble size and Pd coverage, indicating that surfaces with more Pd are more likely to induce an EtOH reaction instead of desorb. Our theoretical results show that the synergistic influence of atomic ensemble and electronic effects on Pd/Au(111) can lead to different H 2 association energies and EtOH dehydrogenation capacities at different Pd ensembles. These results provide mechanistic insights into ethanol's dehydrogenation interactions with different sites on the Pd-Au surface and can potentially aid in bimetallic catalyst design for applications such as fuel cells.

  13. Cross-sections of 197Au(n,α)198Au and 63Cu(n,α)64Cu induced by 252Cf neutrons

    International Nuclear Information System (INIS)

    Mandal, Ranjita; Sengupta, D.; Roy, Malobika; Naik, Mamta; Bhoraskar, V.N.

    2014-01-01

    Analytical work, employing nuclear techniques, is normally carried out through (n,α) reaction because of the availability of neutrons either from reactors or laboratory sources such as Sb-Be, Am-Be, Ra-Be, Po-Be, 252 Cf, etc. The laboratory neutron sources are though portable and adaptable to a particular experimental arrangement, suffer from the disadvantage of slow neutron yield (except 252 Cf). In this set up since the neutrons available are monoenergetic, it was thought appropriate to initiate a program to measure cross-sections of a few nuclear reactions which have practical applications. Earlier studies on cross-section measurement of the reaction 197 Au(n,α) 198 Au and 63 Cu(n,α) 64 Cu has been carried out using different sources, monitors and techniques

  14. Nuclear Stopping in Central Au+Au Collisions at RHIC Energies

    Directory of Open Access Journals (Sweden)

    Ying Yuan

    2014-01-01

    Full Text Available Nuclear stopping in central Au+Au collisions at relativistic heavy-ion collider (RHIC energies is studied in the framework of a cascade mode and the modified ultrarelativistic quantum molecular dynamics (UrQMD transport model. In the modified mode, the mean field potentials of both formed and “preformed” hadrons (from string fragmentation are considered. It is found that the nuclear stopping is increasingly influenced by the mean-field potentials in the projectile and target regions with the increase of the reaction energy. In the central region, the calculations of the cascade model considering the modifying factor can describe the experimental data of the PHOBOS collaboration.

  15. D and $^{3}He$ production in $\\sqrt{s}$ = 130 GeV Au + Au collisions

    CERN Document Server

    Adler, C; Allgower, C; Amonett, J; Anderson, B D; Anderson, M; Averichev, G S; Balewski, J T; Barannikova, O Yu; Barnby, L S; Baudot, J; Bekele, S; Belaga, V V; Bellwied, R; Berger, J; Bichsel, H; Bland, L C; Blyth, C O; Bonner, B E; Boucham, A; Brandin, A B; Cadman, R V; Caines, H; Calderón de la Barca-Sanchez, M; Cardenas, A; Carroll, J; Castillo, J; Castro, M; Cebra, D; Chattopadhyay, S; Chen, M L; Chen, Y; Chernenko, S P; Cherney, M; Chikanian, A; Choi, B; Christie, W; Cormier, T M; Cramer, J G; Crawford, H J; De Mello, M; Deng, W S; Derevshchikov, A A; Didenko, L; Draper, J E; Dunin, V B; Dunlop, J C; Eckardt, V; Efimov, L G; Emelianov, V; Engelage, J; Eppley, G; Erazmus, B; Fachini, P; Faine, V; Finch, E; Fisyak, Yu; Flierl, D; Foley, Kenneth J; Fu, J; Gagunashvili, N D; Gans, J; Gaudichet, L; Germain, M; Geurts, F J M; Ghazikhanian, V; Grabski, J; Grachov, O A; Greiner, D E; Grigoriev, V; Guedon, M; Guschin, E; Hallman, T J; Hardtke, D; Harris, J W; Heffner, M; Heppelmann, S; Herston, T; Hippolyte, B; Hirsch, A; Hjort, E; Hoffmann, G W; Horsley, M; Huang, H Z; Humanic, T J; Hümmler, H; Igo, G; Ishihara, A; Ivanshin, Yu I; Jacobs, P; Jacobs, W W; Janik, M; Johnson, I; Jones, P G; Judd, E; Kaneta, M; Kaplan, M; Keane, D; Kisiel, A; Klay, J L; Klein, S R; Klyachko, A A; Konstantinov, A S; Kotchenda, L; Kovalenko, A D; Krämer, M; Kravtsov, P; Krüger, K; Kuhn, C; Kulikov, A V; Kunde, G J; Kunz, C L; Kutuev, R K; Kuznetsov, A A; Lakehal-Ayat, L; Lamas-Valverde, J; Lamont, M A C; Landgraf, J M; Lange, S; Lansdell, C P; Lasiuk, B; Laue, F; Lebedev, A; LeCompte, T J; Lednicky, R; Leontiev, V M; Le Vine, M J; Li, Q; Lindenbaum, S J; Lisa, M A; Ljubicic, T; Llope, W J; Lo Curto, G; Long, H; Longacre, R S; López-Noriega, M; Love, W A; Lynn, D; Majka, R; Margetis, S; Martin, L; Marx, J; Matis, H S; Matulenko, Yu A; McShane, T S; Meissner, F; Melnik, Yu M; Meshchanin, A P; Messer, M; Miller, M L; Milosevich, Z; Minaev, N G; Mitchell, J; Moiseenko, V A; Moltz, D; Moore, C F; Morozov, V; De Moura, M M; Munhoz, M G; Mutchler, G S; Nelson, J M; Nevski, P; Nikitin, V A; Nogach, L V; Norman, B; Nurushev, S B; Odyniec, Grazyna Janina; Ogawa, A; Okorokov, V; Oldenburg, M; Oson, D; Paic, G; Pandey, S U; Panebratsev, Yu A; Panitkin, S Y; Pavlinov, A I; Pawlak, T; Perevozchikov, V; Peryt, W; Petrov, V A; Platner, E D; Pluta, J; Porile, N; Porter, J; Poskanzer, A M; Potrebenikova, E V; Prindle, D J; Pruneau, C A; Radomski, S; Rai, G; Ravel, O; Ray, R L; Razin, S V; Reichhold, D M; Reid, J G; Retière, F; Ridiger, A; Ritter, H G; Roberts, J B; Rogachevski, O V; Romero, J L; Roy, C; Russ, D; Rykov, V L; Sakrejda, I; Sandweiss, J; Saulys, A C; Savin, I; Schambach, J; Scharenberg, R P; Schmitz, N; Schröder, L S; Schüttauf, A; Schweda, K; Seger, J E; Seliverstov, D M; Seyboth, P; Shahaliev, E; Shestermanov, K E; Shimansky, S S; Shvetcov, V S; Skoro, G P; Smirnov, N; Snellings, R; Sowinski, J; Spinka, H M; Srivastava, B; Stephenson, E J; Stock, Reinhard; Stolpovsky, A; Strikhanov, M N; Stringfellow, B C; Struck, C; Suaide, A A P; Sugarbaker, E R; Suire, C; Sumbera, M; Symons, T J M; Szanto de Toledo, A; Szarwas, P; Takahashi, J; Tang, A H; Thomas, J H; Tikhomirov, V; Trainor, T A; Trentalange, S; Tokarev, M; Tonjes, M B; Trofimov, V; Tsai, O; Turner, K; Ullrich, T S; Underwood, D G; Van Buren, G; Van der Molen, A; Vanyashin, A V; Vasilevski, I M; Vasilev, A N; Vigdor, S E; Voloshin, S A; Wang, F; Ward, H; Watson, J W; Wells, R; Wenaus, T J; Westfall, G D; Whitten, C; Wieman, H H; Willson, R; Wissink, S W; Witt, R; Xu, N; Xu, Z; Yakutin, A E; Yamamoto, E; Yang, J; Yepes, P; Yokosawa, A; Yurevich, V I; Zanevsky, Yu V; Zborovský, I; Zhang, H; Zhang, W M; Zoulkarneev, R; Zubarev, A N; 10.1103/PhysRevLett.87.262301

    2001-01-01

    The first measurements of light antinucleus production in Au + Au collisions at the Relativistic Heavy-Ion Collider are reported. The observed production rates for d and /sup 3/He are much larger than in lower energy nucleus-nucleus collisions. A coalescence model analysis of the yields indicates that there is little or no increase in the antinucleon freeze-out volume compared to collisions at CERN SPS energy. These analyses also indicate that the 3He freeze-out volume is smaller than the d freeze-out volume. (22 refs).

  16. Gold nanoparticle (AuNPs) and gold nanopore (AuNPore) catalysts in organic synthesis.

    Science.gov (United States)

    Takale, Balaram S; Bao, Ming; Yamamoto, Yoshinori

    2014-04-07

    Organic synthesis using gold has gained tremendous attention in last few years, especially heterogeneous gold catalysis based on gold nanoparticles has made its place in almost all organic reactions, because of the robust and green nature of gold catalysts. In this context, gold nanopore (AuNPore) with a 3D metal framework is giving a new dimension to heterogeneous gold catalysts. Interestingly, AuNPore chemistry is proving better than gold nanoparticles based chemistry. In this review, along with recent advances, major discoveries in heterogeneous gold catalysis are discussed.

  17. Balance functions from Au+Au, d+Au, and p+p collisions at root s(NN)=200 GeV

    Czech Academy of Sciences Publication Activity Database

    Aggarwal, M. M.; Ahammed, Z.; Alakhverdyants, A. V.; Alekseev, I.; Alford, J.; Anderson, B.D.; Arkhipkin, D.; Averichev, G. S.; Balewski, J.; Barnby, L. S.; Baumgart, S.; Beavis, D.R.; Bellwied, R.; Betancourt, M.J.; Betts, R. R.; Bhasin, A.; Bhati, A.K.; Bichsel, H.; Bielčík, Jaroslav; Bielčíková, Jana; Biritz, B.; Bland, L.C.; Bonner, B.E.; Bouchet, J.; Braidot, E.; Brandin, A.V.; Bridgeman, A.; Bruna, E.; Bueltmann, S.; Bunzarov, I.; Burton, T. P.; Cai, X.Z.; Caines, H.; Sanchez, M.C.D.; Catu, O.; Cebra, D.; Cendejas, R.; Cervantes, M.C.; Chajecki, Z.; Chaloupka, Petr; Chattopadhyay, S.; Chen, H.F.; Chen, J.H.; Chen, J.Y.; Cheng, J.; Cherney, M.; Chikanian, A.; Choi, K.E.; Christie, W.; Chung, P.; Clarke, R.F.; Codrington, M.J.M.; Corliss, R.; Cramer, J. G.; Crawford, H. J.; Das, D.; Dash, S.; Leyva, A.D.; De Silva, L.C.; Debbe, R.R.; Dedovich, T. G.; Derevschikov, A.A.; de Souza, R.D.; Didenko, L.; Djawotho, P.; Dogra, S.M.; Dong, X.; Drachenberg, J.L.; Draper, J. E.; Dunlop, J.C.; Mazumdar, M.R.D.; Efimov, L.G.; Elhalhuli, E.; Elnimr, M.; Engelage, J.; Eppley, G.; Erazmus, B.; Estienne, M.; Eun, L.; Evdokimov, O.; Fachini, P.; Fatemi, R.; Fedorisin, J.; Fersch, R.G.; Filip, P.; Finch, E.; Fine, V.; Fisyak, Y.; Gagliardi, C. A.; Gangaharan, D.R.; Ganti, M. S.; Garcia-Solis, E.J.; Geromitsos, A.; Geurts, F.; Ghazikhanian, V.; Ghosh, P.; Gorbunov, Y.N.; Gordon, A.; Grebenyuk, O.; Grosnick, D.; Guertin, S.M.; Gupta, A.; Gupta, N.; Guryn, W.; Haag, B.; Hamed, A.; Han, L.X.; Harris, J.W.; Hays-Wehle, J.P.; Heinz, M.; Heppelmann, S.; Hirsch, A.; Hjort, E.; Hoffmann, A.M.; Hoffmann, G.W.; Hofman, D.J.; Horner, M.J.; Huang, B.; Huang, H.Z.; Humanic, T.J.; Huo, L.; Igo, G.; Jacobs, P.; Jacobs, W.W.; Jena, C.; Jin, F.; Jones, C.L.; Jones, P.G.; Joseph, J.; Judd, E.G.; Kabana, S.; Kajimoto, K.; Kang, K.; Kapitán, Jan; Kauder, K.; Keane, D.; Kechechyan, A.; Kettler, D.; Kikola, D.P.; Kiryluk, J.; Kisiel, A.; Klein, S.R.; Knospe, A.G.; Kocoloski, A.; Koetke, D.D.; Kollegger, T.; Konzer, J.; Koralt, I.; Koroleva, L.; Korsch, W.; Kotchenda, L.; Kushpil, Vasilij; Kravtsov, P.; Krueger, K.; Krus, M.; Kumar, L.; Kurnadi, P.; Lamont, M.A.C.; Landgraf, J.M.; LaPointe, S. (ed.); Lauret, J.; Lebedev, A.; Lednický, Richard; Lee, Ch.; Lee, J.H.; Leight, W.; LeVine, M.J.; Li, C.; Li, L.; Li, N.; Li, W.; Li, X.; Li, Y.; Li, Z.M.; Lin, G.; Lindenbaum, S.J.; Lisa, M.A.; Liu, F.; Liu, H.; Liu, J.; Ljubicic, T.; Llope, W.J.; Longacre, R.S.; Love, W.A.; Lu, Y.; Luo, X.; Ma, G.L.; Ma, Y.G.; Mahapatra, D. P.; Majka, R.; Mall, O.I.; Mangotra, L.K.; Manweiler, R.; Margetis, S.; Markert, C.; Masui, H.; Matis, H.S.; Matulenko, Yu.A.; McDonald, D.; McShane, T.S.; Meschanin, A.; Milner, R.; Minaev, N.G.; Mioduszewski, S.; Mischke, A.; Mitrovski, M.K.; Mohanty, B.; Mondal, M.M.; Morozov, B.; Morozov, D.A.; Munhoz, M. G.; Nandi, B.K.; Nattrass, C.; Nayak, T. K.; Nelson, J.M.; Netrakanti, P.K.; Ng, M.J.; Nogach, L.V.; Nurushev, S.B.; Odyniec, G.; Ogawa, A.; Okorokov, V.; Oldag, E.W.; Olson, D.; Pachr, M.; Page, B.S.; Pal, S.K.; Pandit, Y.; Panebratsev, Yu.; Pawlak, T.; Peitzmann, T.; Perevoztchikov, V.; Perkins, C.; Peryt, W.; Phatak, S.C.; Pile, P.; Planinic, M.; Ploskon, M.A.; Pluta, J.; Plyku, D.; Poljak, N.; Poskanzer, A.M.; Potukuchi, B.V.K.S.; Powell, C.B.; Prindle, D.; Pruneau, C.; Pruthi, N.K.; Pujahari, P.R.; Putschke, J.; Raniwala, R.; Raniwala, S.; Ray, R.L.; Redwine, R.; Reed, R.; Ritter, H.G.; Roberts, J.B.; Rogachevskiy, O.V.; Romero, J.L.; Rose, A.; Roy, C.; Ruan, L.; Sahoo, R.; Sakai, S.; Sakrejda, I.; Sakuma, T.; Salur, S.; Sandweiss, J.; Sangaline, E.; Schambach, J.; Scharenberg, R.P.; Schmitz, N.; Schuster, T.R.; Seele, J.; Seger, J.; Selyuzhenkov, I.; Seyboth, P.; Shahaliev, E.; Shao, M.; Sharma, M.; Shi, S.S.; Sichtermann, E.P.; Simon, F.; Singaraju, R.N.; Skoby, M.J.; Smirnov, N.; Sorensen, P.; Sowinski, J.; Spinka, H.M.; Srivastava, B.; Stanislaus, T.D.S.; Staszak, D.; Stevens, J.R.; Stock, R.; Strikhanov, M.; Stringfellow, B.; Suaide, A. A. P.; Suarez, M.C.; Subba, N.L.; Šumbera, Michal; Sun, X.M.; Sun, Y.; Sun, Z.; Surrow, B.; Svirida, D.N.; Symons, T.J.M.; de Toledo, A. S.; Takahashi, J.; Tang, A.H.; Tang, Z.; Tarini, L.H.; Tarnowsky, T.; Thein, D.; Thomas, J.H.; Tian, J.; Timmins, A.R.; Timoshenko, S.; Tlustý, David; Tokarev, M. V.; Trainor, T.A.; Tram, V.N.; Trentalange, S.; Tribble, R. E.; Tsai, O.D.; Ulery, J.; Ullrich, T.; Underwood, D.G.; Van Buren, G.; van Leeuwen, M.; van Nieuwenhuizen, G.; Vanfossen, J.A.; Varma, R.; Vasconcelos, G.M.S.; Vasiliev, A. N.; Videbaek, F.; Viyogi, Y. P.; Vokal, S.; Voloshin, S.A.; Wada, M.; Walker, M.; Wang, F.; Wang, G.; Wang, H.; Wang, J.S.; Wang, Q.; Wang, X.L.; Wang, Y.; Webb, G.; Westfall, G.D.; Whitten, C.; Wieman, H.; Wissink, S.W.; Witt, R.; Wu, Y.F.; Xie, W.; Xu, N.; Xu, Q.H.; Xu, W.; Xu, Y.; Xu, Z.; Xue, L.; Yang, Y.; Yepes, P.; Yip, K.; Yoo, I.K.; Yue, Q.; Zawisza, M.; Zbroszczyk, H.; Zhan, W.; Zhang, J.B.; Zhang, S.; Zhang, W.M.; Zhang, X.P.; Zhang, Y.; Zhang, Z.P.; Zhao, J.; Zhong, C.; Zhou, J.; Zhou, W.; Zhu, X.; Zhu, Y.H.; Zoulkarneev, R.; Zoulkarneeva, Y.

    2010-01-01

    Roč. 82, č. 2 (2010), 024905/1-024905/16 ISSN 0556-2813 Institutional research plan: CEZ:AV0Z10480505; CEZ:AV0Z10100502 Keywords : HEAVY-ION COLLISIONS * AU-AU COLLISIONS * TIME PROJECTION CHAMBER Subject RIV: BG - Nuclear, Atomic and Molecular Physics, Colliders Impact factor: 3.416, year: 2010

  18. Azimuthal di-hadron correlations in d plus Au and Au plus Au collisions at root s(NN)=200 GeV measured at the STAR detector

    Czech Academy of Sciences Publication Activity Database

    Aggarwal, M. M.; Ahammed, Z.; Alakhverdyants, A. V.; Alekseev, I.; Alford, J.; Anderson, B.D.; Arkhipkin, D.; Averichev, G. S.; Balewski, J.; Barnby, L. S.; Baumgart, S.; Beavis, D.R.; Bellwied, R.; Betancourt, M.J.; Betts, R. R.; Bhasin, A.; Bhati, A.K.; Bichsel, H.; Bielčík, Jaroslav; Bielčíková, Jana; Biritz, B.; Bland, L.C.; Bonner, B.E.; Bouchet, J.; Braidot, E.; Brandin, A.V.; Bridgeman, A.; Bruna, E.; Bueltmann, S.; Bunzarov, I.; Burton, T. P.; Cai, X.Z.; Caines, H.; Sanchez, M.C.D.; Catu, O.; Cebra, D.; Cendejas, R.; Cervantes, M.C.; Chajecki, Z.; Chaloupka, Petr; Chattopadhyay, S.; Chen, H.F.; Chen, J.H.; Chen, J.Y.; Cheng, J.; Cherney, M.; Chikanian, A.; Choi, K.E.; Christie, W.; Chung, P.; Clarke, R.F.; Codrington, M.J.M.; Corliss, R.; Cramer, J. G.; Crawford, H. J.; Das, D.; Dash, S.; Leyva, A.D.; De Silva, L.C.; Debbe, R.R.; Dedovich, T. G.; Derevschikov, A.A.; de Souza, R.D.; Didenko, L.; Djawotho, P.; Dogra, S.M.; Dong, X.; Drachenberg, J.L.; Draper, J. E.; Dunlop, J.C.; Mazumdar, M.R.D.; Efimov, L.G.; Elhalhuli, E.; Elnimr, M.; Engelage, J.; Eppley, G.; Erazmus, B.; Estienne, M.; Eun, L.; Evdokimov, O.; Fachini, P.; Fatemi, R.; Fedorisin, J.; Fersch, R.G.; Filip, P.; Finch, E.; Fine, V.; Fisyak, Y.; Gagliardi, C. A.; Gangaharan, D.R.; Ganti, M. S.; Garcia-Solis, E.J.; Geromitsos, A.; Geurts, F.; Ghazikhanian, V.; Ghosh, P.; Gorbunov, Y.N.; Gordon, A.; Grebenyuk, O.; Grosnick, D.; Guertin, S.M.; Gupta, A.; Gupta, N.; Guryn, W.; Haag, B.; Hamed, A.; Han, L.X.; Harris, J.W.; Hays-Wehle, J.P.; Heinz, M.; Heppelmann, S.; Hirsch, A.; Hjort, E.; Hoffmann, A.M.; Hoffmann, G.W.; Hofman, D.J.; Horner, M.J.; Huang, B.; Huang, H.Z.; Humanic, T.J.; Huo, L.; Igo, G.; Jacobs, P.; Jacobs, W.W.; Jena, C.; Jin, F.; Jones, C.L.; Jones, P.G.; Joseph, J.; Judd, E.G.; Kabana, S.; Kajimoto, K.; Kang, K.; Kapitán, Jan; Kauder, K.; Keane, D.; Kechechyan, A.; Kettler, D.; Kikola, D.P.; Kiryluk, J.; Kisiel, A.; Klein, S.R.; Knospe, A.G.; Kocoloski, A.; Koetke, D.D.; Kollegger, T.; Konzer, J.; Koralt, I.; Koroleva, L.; Korsch, W.; Kotchenda, L.; Kushpil, Vasilij; Kravtsov, P.; Krueger, K.; Krus, M.; Kumar, L.; Kurnadi, P.; Lamont, M.A.C.; Landgraf, J.M.; LaPointe, S. (ed.); Lauret, J.; Lebedev, A.; Lednický, Richard; Lee, Ch.; Lee, J.H.; Leight, W.; LeVine, M.J.; Li, C.; Li, L.; Li, N.; Li, W.; Li, X.; Li, Y.; Li, Z.M.; Lin, G.; Lindenbaum, S.J.; Lisa, M.A.; Liu, F.; Liu, H.; Liu, J.; Ljubicic, T.; Llope, W.J.; Longacre, R.S.; Love, W.A.; Lu, Y.; Luo, X.; Ma, G.L.; Ma, Y.G.; Mahapatra, D. P.; Majka, R.; Mall, O.I.; Mangotra, L.K.; Manweiler, R.; Margetis, S.; Markert, C.; Masui, H.; Matis, H.S.; Matulenko, Yu.A.; McDonald, D.; McShane, T.S.; Meschanin, A.; Milner, R.; Minaev, N.G.; Mioduszewski, S.; Mischke, A.; Mitrovski, M.K.; Mohanty, B.; Mondal, M.M.; Morozov, B.; Morozov, D.A.; Munhoz, M. G.; Nandi, B.K.; Nattrass, C.; Nayak, T. K.; Nelson, J.M.; Netrakanti, P.K.; Ng, M.J.; Nogach, L.V.; Nurushev, S.B.; Odyniec, G.; Ogawa, A.; Okorokov, V.; Oldag, E.W.; Olson, D.; Pachr, M.; Page, B.S.; Pal, S.K.; Pandit, Y.; Panebratsev, Yu.; Pawlak, T.; Peitzmann, T.; Perevoztchikov, V.; Perkins, C.; Peryt, W.; Phatak, S.C.; Pile, P.; Planinic, M.; Ploskon, M.A.; Pluta, J.; Plyku, D.; Poljak, N.; Poskanzer, A.M.; Potukuchi, B.V.K.S.; Powell, C.B.; Prindle, D.; Pruneau, C.; Pruthi, N.K.; Pujahari, P.R.; Putschke, J.; Raniwala, R.; Raniwala, S.; Ray, R.L.; Redwine, R.; Reed, R.; Ritter, H.G.; Roberts, J.B.; Rogachevskiy, O.V.; Romero, J.L.; Rose, A.; Roy, C.; Ruan, L.; Sahoo, R.; Sakai, S.; Sakrejda, I.; Sakuma, T.; Salur, S.; Sandweiss, J.; Sangaline, E.; Schambach, J.; Scharenberg, R.P.; Schmitz, N.; Schuster, T.R.; Seele, J.; Seger, J.; Selyuzhenkov, I.; Seyboth, P.; Shahaliev, E.; Shao, M.; Sharma, M.; Shi, S.S.; Sichtermann, E.P.; Simon, F.; Singaraju, R.N.; Skoby, M.J.; Smirnov, N.; Sorensen, P.; Sowinski, J.; Spinka, H.M.; Srivastava, B.; Stanislaus, T.D.S.; Staszak, D.; Stevens, J.R.; Stock, R.; Strikhanov, M.; Stringfellow, B.; Suaide, A. A. P.; Suarez, M.C.; Subba, N.L.; Šumbera, Michal; Sun, X.M.; Sun, Y.; Sun, Z.; Surrow, B.; Svirida, D.N.; Symons, T.J.M.; de Toledo, A. S.; Takahashi, J.; Tang, A.H.; Tang, Z.; Tarini, L.H.; Tarnowsky, T.; Thein, D.; Thomas, J.H.; Tian, J.; Timmins, A.R.; Timoshenko, S.; Tlustý, David; Tokarev, M. V.; Trainor, T.A.; Tram, V.N.; Trentalange, S.; Tribble, R. E.; Tsai, O.D.; Ulery, J.; Ullrich, T.; Underwood, D.G.; Van Buren, G.; van Leeuwen, M.; van Nieuwenhuizen, G.; Vanfossen, J.A.; Varma, R.; Vasconcelos, G.M.S.; Vasiliev, A. N.; Videbaek, F.; Viyogi, Y. P.; Vokal, S.; Voloshin, S.A.; Wada, M.; Walker, M.; Wang, F.; Wang, G.; Wang, H.; Wang, J.S.; Wang, Q.; Wang, X.L.; Wang, Y.; Webb, G.; Westfall, G.D.; Whitten, C.; Wieman, H.; Wissink, S.W.; Witt, R.; Wu, Y.F.; Xie, W.; Xu, N.; Xu, Q.H.; Xu, W.; Xu, Y.; Xu, Z.; Xue, L.; Yang, Y.; Yepes, P.; Yip, K.; Yoo, I.K.; Yue, Q.; Zawisza, M.; Zbroszczyk, H.; Zhan, W.; Zhang, J.B.; Zhang, S.; Zhang, W.M.; Zhang, X.P.; Zhang, Y.; Zhang, Z.P.; Zhao, J.; Zhong, C.; Zhou, J.; Zhou, W.; Zhu, X.; Zhu, Y.H.; Zoulkarneev, R.; Zoulkarneeva, Y.

    2010-01-01

    Roč. 82, č. 2 (2010), 024912/1-024912/14 ISSN 0556-2813 Institutional research plan: CEZ:AV0Z10480505; CEZ:AV0Z10100502 Keywords : AU+AU COLLISIONS * RADIATION * PLASMA Subject RIV: BG - Nuclear, Atomic and Molecular Physics, Colliders Impact factor: 3.416, year: 2010

  19. Electron diffraction on amorphous and crystalline AuAl2 , AuGa2 and AuIn2 thin films

    International Nuclear Information System (INIS)

    Bohorquez, A.

    1991-01-01

    Experimental (in situ) measurements of electron diffraction and resistivity of amorphous and crystalline AuAl 2 , AuGa 2 and AuIn 2 thin films were performed. Thin films were produced by quench condensation. Interference and atomic distribution functions were analyzed assuming the same short range order for the three systems in the amorphous phase. The experimental results do not agree with this assumption, giving evidence that the short range order is not the same for the three amorphous systems. Further discussion of interference and atomic distribution functions shows a more evident tendency in amorphous AuIn 2 where short order of AuIn 2 and In can be inferred. (Author)

  20. Conjugated polymer P3HT-Au hybrid nanostructures for enhancing photocatalytic activity.

    Science.gov (United States)

    Jana, Bikash; Bhattacharyya, Santanu; Patra, Amitava

    2015-06-21

    Metal-semiconductor nanostructures have been the subject of great interest, mainly due to their interesting optical properties and their potential applications in light harvesting, photocatalysis and photovoltaic devices. Here, we have designed raspberry type organic-inorganic hybrid nanostructures of the poly-3-hexylthiophene (P3HT)-Au nanoparticle (NP) composite by a simple solution based synthetic method. The electronic interaction of semiconducting P3HT polymer nanoparticles with Au nanoparticles exhibits a bathochromic shift of absorption bands and significant photoluminescence quenching of P3HT nanoparticles in this organic-inorganic hybrid system. The photocatalytic activity of this raspberry type hybrid nanostructure is demonstrated under the visible light irradiation and the degradation efficiency is found to be 90.6%. Such organic-inorganic hybrid nanostructures made of a semiconducting polymer and plasmonic nanoparticles could pave the way for designing new optical based materials for applications in photocatalytic and light harvesting systems.

  1. Au-Rh and Au-Pd nanocatalysts supported on rutile titania nanorods: structure and chemical stability.

    Science.gov (United States)

    Konuspayeva, Zere; Afanasiev, Pavel; Nguyen, Thanh-Son; Di Felice, Luca; Morfin, Franck; Nguyen, Nhat-Tai; Nelayah, Jaysen; Ricolleau, Christian; Li, Z Y; Yuan, Jun; Berhault, Gilles; Piccolo, Laurent

    2015-11-14

    Au, Rh, Pd, Au-Rh and Au-Pd nanoparticles (NPs) were synthesized by colloidal chemical reduction and immobilized on hydrothermally-prepared rutile titania nanorods. The catalysts were characterized by aberration-corrected TEM/STEM, XPS, and FTIR, and were evaluated in the hydrogenation of tetralin in the presence of H2S. Oxidizing and reducing thermal treatments were employed to remove the polyvinyl alcohol (PVA) surfactant. Reduction in H2 at 350 °C was found efficient for removing the PVA while preserving the size (ca. 3 nm), shape and bimetallic nature of the NPs. While Au-Pd NPs are alloyed at the atomic scale, Au-Rh NPs contain randomly distributed single-phase domains. Calcination-reduction of Au-Rh NPs mostly leads to separated Au and Rh NPs, while pre-reduction generates a well-defined segregated structure with Rh located at the interface between Au and TiO2 and possibly present around the NPs as a thin overlayer. Both the titania support and gold increase the resistance of Rh and Pd to oxidation. Furthermore, although detrimental to tetralin hydrogenation initial activity, gold stabilizes the NPs against surface sulfidation in the presence of 50 ppm H2S, leading to increased catalytic performances of the Au-Rh and Au-Pd systems as compared to their Rh and Pd counterparts.

  2. The study by means of a photomultiplier of the scintillations produced by {alpha} particles striking a zinc sulphide screen; Etude, au photomultiplicateur, des scintillations produites par les particules {alpha} dans un ecran de sulfure de zinc. Application a la numeration precise des particules {alpha}

    Energy Technology Data Exchange (ETDEWEB)

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

    1955-06-15

    The object of the study is the accurate counting of {alpha} particles by p-m. detection of their scintillations upon impact with a zinc sulphide screen. The main advantage of the method is the extreme simplicity of the electronics used: the possibility of obtaining a utilizable pulse from the p-m. (EMI5311) without any amplification, and in linear response, is demonstrated. The scintillation produced by an impact on Zn-S has also been studied experimentally. The decrease of light intensity in relation to time may be interpreted by the exponential relation: I = I{sub 0} exp (-t / {tau}) whereby {tau} = (39 {+-} 0,1) 10{sup -6} s. The relation between scintillation intensity and remaining trajectory after travel through a given air-space has also been determined. Possible suitable applications of this method of {alpha} counting are those where good stability and low background are necessary. Results stated bear on air contamination studies, isotopic composition variation measurement of uranium, bismuth content measurement in alloys by irradiation of specimens in a thermal neutron flux and {alpha} count on the Po formed. (author) [French] Ce travail est consacre a l'etude de la numeration precise des particules {alpha} par detection au photomultiplicateur des scintillations produites par ces particules dans un ecran de sulfure de zinc. Le principal avantage de cette methode reside dans l'extreme simplicite de l'appareillage electronique; il est en effet montre qu'il est possible, tout en convoyant une reponse lineaire, d'obtenir du photomultiplicateur (EMI5311) un signal electrique utilisable sans aucune amplification. La scintillation produite par l'impact des particules {alpha} sur un ecran de Zn-S est etudiee experimentalement. La decroissance de l'intensite lumineuse en fonction du temps est interpretable par la relation exponentielle I = I{sub 0} exp (-t / {tau}) avec {tau} = (39 {+-} 0,1) 10{sup -6} s. La relation entre l

  3. Magnetic Fe{sub 3}O{sub 4}-Au core-shell nanostructures for surface enhanced Raman scattering

    Energy Technology Data Exchange (ETDEWEB)

    Wheeler, D.A.; Adams, S.A.; Zhang, J.Z. [Department of Chemistry and Biochemistry, University of California, Santa Cruz, Santa Cruz, CA 95064 (United States); Lopez-Luke, T. [Department of Chemistry and Biochemistry, University of California, Santa Cruz, Santa Cruz, CA 95064 (United States); Cento de Investigaciones en Optica, A.P. 1-948 Leon, Gto. 37150 (Mexico); Torres-Castro, A. [Universidad Autonoma de Nuevo Leon, A.P. 126-F, Monterrey, NL, 66450 (Mexico)

    2012-11-15

    The synthesis, structural and optical characterization, and application of superparamagnetic and water-dispersed Fe{sub 3}O{sub 4}-Au core-shell nanoparticles for surface enhanced Raman scattering (SERS) is reported. The structure of the nanoparticles was determined by scanning transmission electron microscopy (STEM) and high-resolution transmission electron microscopy (HRTEM). STEM images of the Fe{sub 3}O{sub 4}-Au core-shell nanoparticles reveal an average diameter of 120 nm and a high degree of surface roughness. The nanoparticles, which display superparamagnetic properties due to the core Fe{sub 3}O{sub 4} material, exhibit a visible surface plasmon resonance (SPR) peaked at 580 nm due to the outer gold shell. The nanoparticles are used as a substrate for surface enhanced Raman scattering (SERS) with rhodamine 6G (R6G) as a Raman reporter molecule. The SERS enhancement factor is estimated to be on the order of 10{sup 6}, which is {proportional_to} 2 times larger than that of conventional gold nanoparticles (AuNPs) under similar conditions. Significantly, magnetically-induced aggregation of the Fe{sub 3}O{sub 4}-Au core-shell nanoparticles substantially enhanced SERS activity compared to non-magnetically-aggregated Fe{sub 3}O{sub 4}-Au nanoparticles. This is attributed to both increased scattering from the aggregates as well as ''hot spots'' due to more junction sites in the magnetically-induced aggregates. The magnetic properties of the Fe{sub 3}O{sub 4} core, coupled with the optical properties of the Au shell, make the Fe{sub 3}O{sub 4}-Au nanoparticles unique for various potential applications including biological sensing and therapy. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  4. Near-infrared Au nanorods in photodynamic therapy, hyperthermia agents, and near-infrared optical imaging

    Science.gov (United States)

    Kuo, Wen-Shuo; Chang, Chich-Neng; Chang, Yi-Ting; Yang, Meng-Heng; Chien, Yi-Hsin; Chen, Shean-Jen; Yeh, Chen-Sheng

    2011-03-01

    The development of multifunctional nanomaterials is currently a topic of interest in the field of nanotechnology. Integrated systems that incorporate therapeutics, molecular targeting, and diagnostic imaging capabilities are considered to be the next generation of multifunctional nanomedicine. In this work, we present the first example of using Au nanorods simultaneously serving not only as photodynamic and photothermal agents to destroy A549 malignant cells but also as optical contrast agents simultaneously to monitor cellular image. Au nanorods were successfully conjugated with hydrophilic photosensitizer, indocyanine green (ICG), to achieve photodynamic therapy (PDT) and hyperthermia. With the combination of PDT and hyperthermia proved to be efficiently killing cancer cells as compared to PDT or hyperthermia treatment alone and enhanced the effectiveness of photodestruction. Moreover, Au nanorods conjugated with ICG displayed high chemical stability and simultaneously acted as a promising cellular image probe. As a result, the preparation of Au nanorods conjugated with photosensitizers as well as their use in biomedical applications is valuable developments in multifunctional nanomaterials.

  5. DNA Origami Directed Au Nanostar Dimers for Single-Molecule Surface-Enhanced Raman Scattering.

    Science.gov (United States)

    Tanwar, Swati; Haldar, Krishna Kanta; Sen, Tapasi

    2017-12-06

    We demonstrate the synthesis of Au nanostar dimers with tunable interparticle gap and controlled stoichiometry assembled on DNA origami. Au nanostars with uniform and sharp tips were immobilized on rectangular DNA origami dimerized structures to create nanoantennas containing monomeric and dimeric Au nanostars. Single Texas red (TR) dye was specifically attached in the junction of the dimerized origami to act as a Raman reporter molecule. The SERS enhancement factors of single TR dye molecules located in the conjunction region in dimer structures having interparticle gaps of 7 and 13 nm are 2 × 10 10 and 8 × 10 9 , respectively, which are strong enough for single analyte detection. The highly enhanced electromagnetic field generated by the plasmon coupling between sharp tips and cores of two Au nanostars in the wide conjunction region allows the accommodation and specific detection of large biomolecules. Such DNA-directed assembled nanoantennas with controlled interparticle separation distance and stoichiometry, and well-defined geometry, can be used as excellent substrates in single-molecule SERS spectroscopy and will have potential applications as a reproducible platform in single-molecule sensing.

  6. Supported Pd-Au Membrane Reactor for Hydrogen Production: Membrane Preparation, Characterization and Testing

    Directory of Open Access Journals (Sweden)

    Adolfo Iulianelli

    2016-05-01

    Full Text Available A supported Pd-Au (Au 7wt% membrane was produced by electroless plating deposition. Permeation tests were performed with pure gas (H2, H2, N2, CO2, CH4 for long time operation. After around 400 h under testing, the composite Pd-Au membrane achieved steady state condition, with an H2/N2 ideal selectivity of around 500 at 420 °C and 50 kPa as transmembrane pressure, remaining stable up to 1100 h under operation. Afterwards, the membrane was allocated in a membrane reactor module for methane steam reforming reaction tests. As a preliminary application, at 420 °C, 300 kPa of reaction pressure, space velocity of 4100 h−1, 40% methane conversion and 35% hydrogen recovery were reached using a commercial Ni/Al2O3 catalyst. Unfortunately, a severe coke deposition affected irreversibly the composite membrane, determining the loss of the hydrogen permeation characteristics of the supported Pd-Au membrane.

  7. Lateral spreading of Au contacts on InP

    Science.gov (United States)

    Fatemi, Navid S.; Weizer, Victor G.

    1990-01-01

    The contact spreading phenomenon observed when small area Au contacts on InP are annealed at temperatures above about 400 C was investigated. It was found that the rapid lateral expansion of the contact metallization which consumes large quantities of InP during growth is closely related to the third stage in the series of solid state reactions that occur between InP and Au, i.e., to the Au3In-to-Au9In4 transition. Detailed descriptions are presented of both the spreading process and the Au3In-to-Au9In4 transition along with arguments that the two processes are manifestations of the same basic phenomenon.

  8. Quantum interference effects in nanostructured Au

    CERN Document Server

    Pratumpong, P; Evans, S D; Johnson, S; Howson, M A

    2002-01-01

    We present results on the magnetoresistance and temperature dependence of the resistivity for nanostructured Au produced by chemical means. The magnetoresistance was typical of highly disordered metals exhibiting quantum interference effects. We fitted the data and were able to determine the spin-orbit scattering relaxation time to be 10 sup - sup 1 sup 2 s and we found the inelastic scattering time at 10 K to be 10 sup - sup 1 sup 1 s. The inelastic scattering rate varied as T sup 3 between 4 and 20 K, which is typical for electron-phonon scattering in disordered metals.

  9. Reconfigurable c-Si/Au hybrid nanoantenna

    Science.gov (United States)

    Chebykin, A. V.; Zalogina, A. S.; Zuev, D. A.; Makarov, S. V.

    2017-09-01

    We have performed numerical optimization of hybrid c-Si/Au nanoantenna's geometry to improve efficiency of NV-centers radiation. We have shown that Purcell factor at the wavelength 635 nm can be as much as 4550 for point light emitter placed in the gap between gold spherical nanoparticle and truncated silicon nanocone. We have demonstrated that electric field enhancement can reach a value of 12.9 at the wavelength of NV-center pumping, 532 nm. Our results can be useful for the development of more efficient sources of single photons based on NV-centers in nanodiamonds.

  10. Que faisons-nous au CERN ?

    CERN Multimedia

    1999-01-01

    Le CERN a pour vocation la science pure, l'étude des questions les plus fondamentales de la nature:Qu'est-ce que la matière ?D'ou vient-elle ? Comment s'agglomère-t-elle en formes complexes comme les étoiles, les planètes et les êtres humains ? Au CERN, les collisions de particules servent à sonder le coeur de la matière et les chercheurs du Laboratoire étudient ces millions de collisions de particules afin de trouver des réponses à ces questions.

  11. Aspects scanographiques des accidents vasculaires cerebraux au ...

    African Journals Online (AJOL)

    Objectif : évaluer la place de la TDM dans les AVC Méthodologie : étude rétrospective réalisée au CHU Campus de Lomé à partir de 314 compte-rendus sur une période de 36 mois. Faisaient partir de l'étude les patients ayant bénéficié d'un examen tomodensitométrique pour un déficit neurologique hémicorporel ...

  12. La problématique de gouvernance sanitaire au nord de l'Afrique ...

    African Journals Online (AJOL)

    la prise de décision par les responsables locaux.25. 4e attribut : la transparence. Plusieurs instruments réglementaires insistent sur l'application de toutes les mesures d'ouverture et de transparence en ce qui concerne l'administration générale. Au sujet des marchés publics, par exemple, l'appel d'offres et la séance ...

  13. Cells for the examination of irradiated plutonium fuel elements - two years operation - may 1961/may 1963 (1963); Cellules pour examen d'elements combustibles au plutonium irradies - deux ans d'exploitation - mai 1961/mai 1963 (1963)

    Energy Technology Data Exchange (ETDEWEB)

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

    1963-07-01

    Within the framework of the 'Rapsodie' fast reactor program, prototype plutonium fuel elements are irradiated and then examined in an {alpha} {beta} {gamma} laboratory at Saclay. This laboratory consists of five in line cells and a lead enclosure microscope. Each cell contains an {alpha} sealed removable box 4 ft 3 in. high, 4 ft 11 in. wide and 5 ft 1 in. deep, fitted with one or two magnetic transmission indirect manipulators. The boxes are contained in an {beta} {gamma} shielded enclosure whose front face is constructed of cast iron panels 21-2/3 in. thick. Nitrogen circulating in a closed loop forms the atmosphere of the boxes. This laboratory is essentially intended for metallurgical research. The functions of the various cells are as follows: transferring and packing, cutting, density measurement and cathodic etching, storage and metallography. Work on radioactive materials began in April 1961. Operational incidents have always been of a material nature only. (author) [French] Dans le cadre du projet de reacteur rapide Rapsodie, des elements combustibles prototypes au plutonium sont, apres irradiation, examines a Saclay dans un laboratoire {alpha} {beta} {gamma}. Celui-ci comprend cinq cellules en ligne et une enceinte en plomb contenant un microscope telecommande. Chaque cellule est constituee d'un caisson etanche (1, 3 m x 1, 5 m x 1, 56m) equipee d'un ou deux manipulateurs indirects a transmissions magnetiques. Les caissons sont places, dans une enceinte {beta} {gamma} dont la face avant est formee de blocs en fonte ayant 55 cm d'epaisseur. L'atmosphere des caissons est de l'azote, circulant en circuit ferme. Ce laboratoire est destine essentiellement a des recherches metallurgiques. Les fonctions des differentes cellules sont: conditionnement et transferts, tronconnage, mesure de densite et polissage ionique, stockage, metallographie. Le travail sur materiaux radioactifs a commence en avril 1961. Les incidents d

  14. Irrigation et information climatique au Burkina Faso (CARA) | CRDI ...

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

    Amélioration de la gouvernance de l'eau et de l'adaptation aux changements climatiques au Cambodge. Le lac Tonlé Sap, au Cambodge, est le plus grand lac d'eau douce en Asie du Sud-Est. Voir davantageAmélioration de la gouvernance de l'eau et de l'adaptation aux changements climatiques au Cambodge ...

  15. Resistance aux antibiotiques des bacteries isolees en 2009 au ...

    African Journals Online (AJOL)

    Objectif : Contribuer à la surveillance de la résistance bactérienne aux antibiotiques au Togo en étudiant la résistance aux antibiotiques des bactéries. Méthode Il s'agit d'une étude descriptive transversale portant sur les comptes rendus des antibiogrammes réalisés du 1er janvier au 31 décembre 2009 au Laboratoire de ...

  16. Acteurs et strategies face aux nouveaux defis securitaires au Benin ...

    African Journals Online (AJOL)

    De même, de nouveaux acteurs dont la communauté des chasseurs au centre et au nord du Bénin, les adeptes du ''Zangbéto'' au sud, les ONG et autres sont nés avec leurs stratégies. Mots clés: acteurs, stratégies, sécurité, développement. English Abstract. Although the security constitute the essential condition for all ...

  17. Conjugated electrical properties of Au nanoparticle–polyaniline network

    Science.gov (United States)

    Usami, Yuki; Otsuka, Yoichi; Naitoh, Yasuhisa; Matsumoto, Takuya

    2017-12-01

    We investigated the electrical properties of a two-dimensional (2D) network consisting of multiple Au nanoparticles (AuNPs) and self-doped polyaniline sulfonate (SPAN). Nonlinear current–voltage (I–V) characteristics with wide variations were observed in the networks. The temperature dependence of the I–V characteristics exhibited a short localization length, suggesting conjugated electronic properties of the AuNP–SPAN network. This result provides a new direction for network-based molecular electronic devices.

  18. Au/Si nanodroplets towards Si nanowires formation: Characterization of the thermal-induced self-organization mechanism

    Science.gov (United States)

    Ruffino, F.; Canino, A.; Grimaldi, M. G.; Giannazzo, F.; Roccaforte, F.; Raineri, V.

    2009-11-01

    Si nanowires grown by the vapour-liquid-solid technique acquired fundamental relevance in the design of innovative nanostructured devices for electronic and optoelectronic applications. Au clusters deposited on Si are widely used as catalysts of the Si nanowires growth. It has been recognized that the starting Au nanoclusters size distribution strongly influences the final distribution of the Si nanowires and therefore the performances of the nanostructured devices based on them. In the present work we illustrate the formation of Au/Si droplets by the deposition of a thick Au film on Si(100) and annealing at 873K for different times. We focus our attention on the study of the evolution of the droplets size distribution and center-to-center distance distribution as a function of the annealing time at 873K using microscopic techniques such as atomic force microscopy, and scanning electron microscopy. The droplets isothermal-induced self-organization is shown to be a ripening process of hemispherical three dimensional structures limited by the Au surface diffusion. The application of the ripening theory allowed us to calculate the surface diffusion coefficient and all the other parameters needed to describe the entire process.

  19. Antimicrobial photodynamic activity and cytocompatibility of Au25(Capt18 clusters photoexcited by blue LED light irradiation

    Directory of Open Access Journals (Sweden)

    Miyata S

    2017-04-01

    spectra of oxidized MTX. Successful application of photoexcited Au clusters to aPDT was demonstrated by dose-dependent decreases in the turbidity of oral bacterial cells. Morphological observation revealed that application of Au clusters stimulated destruction of bacterial cell walls and inhibited biofilm formation. Aggregation of Au clusters around bacterial cells was fluorescently observed. However, photoexcited Au clusters did not negatively affect the adhesion, spreading, and proliferation of mammalian cells, particularly at lower doses. In addition, application of Au clusters demonstrated significantly better cytocompatibility ­compared to MB. We found that a combination of Au25(Capt18 clusters and blue LED irradiation exhibited good antimicrobial effects through 1O2 generation and biosafe characteristics, which is desirable for aPDT in dentistry. Keywords: Aggregatibacter actinomycetemcomitans, antimicrobial photodynamic therapy, photosensitizer, Porphyromonas gingivalis, singlet oxygen, Streptococcus mutans

  20. Magnetic holes in the solar wind between 0.3 AU and 17 AU

    Directory of Open Access Journals (Sweden)

    K. Sperveslage

    2000-01-01

    Full Text Available Magnetic holes (MHs are depressions of the magnetic field magnitude. Turner et al. (1977 identified the first MHs in the solar wind and determined an occurrence rate of 1.5 MHs/d. Winterhalter et al. (1994 developed an automatic identification criterion to search for MHs in Ulysses data in the solar wind between 1 AU and 5.4 AU. We adopt their criterion to expand the search to the heliocentric distances down to 0.3 AU using data from Helios 1 and 2 and up to 17 AU using data from Voyager 2. We relate our observations to two theoretical approaches which describe the so-called linear MHs in which the magnetic vector varies in magnitude rather than direction. Therefore we focus on such linear MHs with a directional change less than 10º. With our observations of about 850 MHs we present the following results: Approximately 30% of all the identified MHs are linear. The maximum angle between the initial magnetic field vector and any vector inside the MH is 20º in average and shows a weak relation to the depth of the MHs. The angle between the initial magnetic field and the minimum variance direction of those structures is large and very probably close to 90º. The MHs are placed in a high β environment even though the average solar wind shows a smaller β. The widths decrease from about 50 proton inertial length in a region between 0.3 AU and 0.4 AU heliocentric distance to about 15 proton inertial length at distances larger than 10 AU. This quantity is correlated with the β of the MH environments with respect to the heliocentric distance. There is a clear preference for the occurrence of depressions instead of compressions. We discuss these results with regard to the main theories of MHs, the mirror instability and the alternative soliton approach. Although our observational results are more consistent with the soliton theory we favour a combination of both. MHs might be the remnants of initial mirror mode structures which can be described as