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Sample records for au champ magnetique

  1. Etude du champ magnetique dans les nuages moleculaires

    NASA Astrophysics Data System (ADS)

    Houde, Martin

    2001-12-01

    Ce travail est une étude du champ magnétique duns l'environnement circumstellaire des étoiles jeunes. Il a pour origine la certitude qu'avait l'auteur qu'il se devait d'être possible de détecter la présence d'un champ magnétique, et de possiblement le caractériser, par le biais d'observations de profils spectraux d'espèces moléculaires ioniques. Il en découle donc qu'un des buts principaux était de prouver que cela est effectivement possible. La thèse comporte alors des éléments théoriques et expérimentaux qui sont à la fois complémentaires et intimement liés. L'aspect théorique est basé sur l'interaction mutuelle que des particules neutres et chargées peuvent avoir l'une sur l'autre daps un plasma faiblement ionisé comme ceux existants daps les nuages moléculaires sites de formation stellaire. Il appert que la présence d'un champ magnétique a un effet direct sur le comportement des ions (via la force de Lorentz) et indirect sur les molécules neutres (via les nombreuses collisions entre les deux types de particules). Une telle interaction est, comme il est maintenant bien connu, présente dans les premières étapes de la formation dune étoile. Il s'agit bien sûr de la diffusion ambipolaire. Nous montrerons qu'il existe cependant un autre type de diffusion, jusqu'ici inconnue, qui se manifeste plus tard au tours de l'évolution des nuages moléculaires. Celle-ci peut avoir un effet dramatique sur l'apparence des profils spectraux (de rotation moléculaire) des espèces ioniques lorsque comparés à ceux qu'exhibent des espèces neutres coexistantes. Mais pour ce faire, il doit y avoir existence de mouvements organisés (des flots ou jets) de matière ou encore la présence de turbulence dans les régions considérées. Une distribution de vélocité du type maxwellienne ne révèlera pas la présence du champ magnétique. Les observations, qui ont pour but de confirmer la théorie, se situent dans le domaine des longueurs d

  2. Reconstruction de la surface de Fermi dans l'etat normal d'un supraconducteur a haute Tc: Une etude du transport electrique en champ magnetique intense

    NASA Astrophysics Data System (ADS)

    Le Boeuf, David

    Des mesures de resistance longitudinale et de resistance de Hall en champ magnetique intense transverse (perpendiculaire aux plans CuO2) ont ete effectuees au sein de monocristaux de YBa2Cu3Oy (YBCO) demacles, ordonnes et de grande purete, afin d'etudier l'etat fondamental des supraconducteurs a haute Tc dans le regime sous-dope. Cette etude a ete realisee en fonction du dopage et de l'orientation du courant d'excitation J par rapport a l'axe orthorhombique b de la structure cristalline. Les mesures en champ magnetique intense revelent par suppression de la supraconductivite des oscillations magnetiques des resistances longitudinale et de Hall dans YBa2Cu 3O6.51 et YBa2Cu4O8. La conformite du comportement de ces oscillations quantiques au formalisme de Lifshitz-Kosevich, apporte la preuve de l'existence d'une surface de Fermi fermee a caractere quasi-2D, abritant des quasiparticules coherentes respectant la statistique de Fermi-Dirac, dans la phase pseudogap d'YBCO. La faible frequence des oscillations quantiques, combinee avec l'etude de la partie monotone de la resistance de Hall en fonction de la temperature indique que la surface de Fermi d'YBCO sous-dope comprend une petite poche de Fermi occupee par des porteurs de charge negative. Cette particularite de la surface de Fermi dans le regime sous-dope incompatible avec les calculs de structure de bande est en fort contraste avec la structure electronique presente dans le regime surdope. Cette observation implique ainsi l'existence d'un point critique quantique dans le diagramme de phase d'YBCO, au voisinage duquel la surface de Fermi doit subir une reconstruction induite par l'etablissement d'une brisure de la symetrie de translation du reseau cristallin sous-jacent. Enfin, l'etude en fonction du dopage de la resistance de Hall et de la resistance longitudinale en champ magnetique intense suggere qu'un ordre du type onde de densite (DW) est responsable de la reconstruction de la surface de Fermi. L'analogie de

  3. Etude des etats electroniques en champ magnetique dans le niveau de Landau N=0 de la tricouche ABC de graphene

    NASA Astrophysics Data System (ADS)

    Rondeau, Maxime

    Dans cet ouvrage nous etudions les phases du gaz d'electrons bidimensionnel dans la tricouche de graphene en empilement ABC. En partant du modele des liaisons fortes et en faisant l'approximation du continuum autour des vallees K +, K-, nous obtenons un modele effectif a deux bandes qui permet de decrire la physique de basse energie des electrons en champ magnetique dans cette structure. Ce modele contient trois orbitales degenerees dans le niveau de Landau N = O. Ce dernier est donc 12N φ, fois degeneres en incluant les degres de liberte de spin et de vallee. En ajoutant l'interaction de Coulomb au systeme et en considerant seulement les remplissages v = -5, -4, -4, 5 afin d'avoir un systeme a trois niveaux, nous etudions le diagramme de phase du gaz d'electrons en fonction d'un biais electrique entre les couches externes. Nous trouvons une phase d'onde de densite de charge bidimensionnelle (ODC2D) comme etat fondamental du systeme. Cette ODC2D se nomme cristal dans ce memoire et nous derivons ses proprietes de transports et ses modes collectifs. Nous discutons egalement du caractere topologique de ce cristal. Notre etude englobe aussi les phases liquides avec ou sans coherence orbitale. Nous concluons notre memoire par l'etude de quelques signatures experimentales des phases du gaz d'electrons dans la tricouche.

  4. Effets Seebeck et Nernst dans les cuprates: Etude de la reconstruction de la surface de Fermi sous champ magnetique intense

    NASA Astrophysics Data System (ADS)

    Laliberte, Francis

    2010-06-01

    Ce memoire presente des mesures de transport thermoelectrique, les effets Seebeck et Nernst, dans une serie d'echantillons de supraconducteurs a haute temperature critique. Des resultats obtenus recemment au Laboratoire National des Champs Magnetiques Intenses a Grenoble sur La1.7Eu0.2Sr0.1 CuO4, La1.675Eu0.2Sr0.125CuO 4, La1.64Eu0.2Sr0.16CuO4, La1.74Eu0.1Sr0.16CuO4 et La 1.4Nd0.4Sr0.2CuO4 sont analyses. Une attention particuliere est accordee aux equations de la theorie semi-classique du transport et leur validite est verifiee. La procedure experimentale et les materiaux utilises pour concevoir les montages de mesures sont expliques en detail. Enfin, un chapitre est dedie a l'explication et l'interpretation des resultats de transport thermoelectrique sur YBa2Cu3O6+delta publies au cours de l'hiver 2010 dans les revues Nature et Physical Review Letters. Les donnees d'effet Seebeck dans les echantillons de La 1.8-x,Eu0.2SrxCuO 4, ou un changement de signe est observe, permettent de conclure a la presence d'une poche d'electrons dans la surface de Fermi qui domine le transport a basse temperature dans la region sous-dopee du diagramme de phase. Cette conclusion est similaire a celle obtenue par des mesures d'effet Hall dans YBa 2Cu3O6+delta et elle cadre bien dans un scenario de reconstruction de la surface de Fermi. Les donnees d'effet Nernst recueillies indiquent que la contribution des fluctuations supraconductrices est limitee a un modeste intervalle de temperature au-dessus de la temperature critique.

  5. Nouvelles approches en theorie du champ moyen dynamique: le cas du pouvoir thermoelectrique et celui de l'effet orbital d'un champ magnetique

    NASA Astrophysics Data System (ADS)

    Arsenault, Louis-Francois

    , cette approche donne une bonne representation de S lorsque le systeme devient coherent. Les calculs montrent aussi que la formule Kelvin est precise lorsque la fonction spectrale des electrons devient incoherente, soit a plus haute temperature. Dans la limite Kelvin, S est essentiellement l'entropie par particule, tel que propose il y a longtemps. Nos resultats demontrent ainsi que la vision purement entropique de S est la bonne dans le regime incoherent, alors que dans le regime coherent, l'approche a frequence infinie est meilleure. Nous avons utilise une methode a la fine pointe, soit le Monte-Carlo quantique en temps continu pour resoudre la DMFT. Pour permettre une exploration rapide du diagramme de phase, nous avons du developper une nouvelle version de la methode des perturbations iterees pour qu'elle soit applicable aussi a forte interaction au-dela de la valeur critique de la transition de Mott. Un autre sujet a aussi ete aborde. L'effet orbital du champ magnetique dans les systemes electroniques fortement correles est une question tres importante et peu developpee. Cela est d'autant plus essentiel depuis la decouverte des oscillations quantiques dans les supraconducteurs a haute temperature (haut- Tc). Par desir de developper une methode la moins biaisee possible, nous avons derive la DMFT lorsqu'un champ se couplant a l'operateur energie cinetique par la substitution de Peierls est present. Ce type d'approche est necessaire pour comprendre entre autres l'effet de la physique de Mott sur des phenomenes tels que les oscillations quantiques. Nous avons obtenu un resultat tres important en demontrant rigoureusement que la relation d'auto-coherence de la DMFT et le systeme intermediaire d'impurete quantique restent les memes. L'effet du champ peut etre contenu dans la fonction de Green locale, ce qui constitue la grande difference avec le cas habituel. Ceci permet de continuer a utiliser les solutionneurs d'impuretes standards, qui sont de plus en plus puissants

  6. Transition de phase quantique de type verrouillage-deverrouillage dans les canaux lineaires coherents des phases en rayures dans les doubles puits quantiques sous champ magnetique perpendiculaire

    NASA Astrophysics Data System (ADS)

    Faribault, Alexandre

    On peut creer un gaz electronique bidimensionnel en utilisant le potentiel de confinement d'une couche mince d'un semiconducteur dans un substrat fait d'une autre semiconducteur de gap plus eleve. L'ajout d'un champ magnetique perpendiculaire au plan de confinement modifie de facon drastique les proprietes du gaz electronique. Pour des densites et des valeurs du champ magnetique adequatement choisies, on obtient un etat fondamental en onde de densite de charge. Dans un systeme compose de deux de ces gaz bidimensionnels suffisamment rapproches l'un de l'autre, on prevoit theoriquement l'existence d'un etat fondamental compose d'une onde de densite de charge dans chacun des puits et d'une serie de regions lineaires ou l'on a une delocalisation coherente des electrons entre les deux puits. Dans cette these, on etudie le comportement a temperature nulle de cet etat fondamental en rayures coherentes. L'etude numerique des modes collectifs de ces phases laisse croire qu'un deverrouillage des canaux coherents est envisageable dans ce systeme. Afin d'etudier cette possibilite, nous construisons d'abord un modele effectif de canaux quasi-unidimensionnels couples qui permettent de reproduire correctement les excitations collectives a basse energie de la phase en rayures coherentes du double puits quantique. Dans un systeme de coordonnees adequatement choisi, ces excitations peuvent etre decrites par des ondes de pseudospin. Les parametres de ce modele effectif simple peuvent etre extraits des calculs des fonctions de reponse realises dans l'approximation Hartree-Fock dependante du temps (appelee aussi Generalized Random Phase Approximation). On constate l'efficacite de ce modele a decrire la dynamique basse energie du systeme pour une certaine plage de distances inter-puits. En retirant de ce modele les contributions a l'hamiltonien provenant des couplages de type Josephson entre les canaux, on obtient alors un systeme ou les canaux sont deverrouilles. Un traitement en

  7. Magnetic field reversals in the Milky Way- "cherchez le champ magnetique".

    NASA Astrophysics Data System (ADS)

    Vallee, J. P.

    1996-04-01

    Radio observations of nearby spiral galaxies have tremendously enhanced our knowledge of their global magnetic field distributions. Recent theoretical developments in the area of dynamos have also helped in the interpretation of magnetic field data in spiral galaxies. When it comes to the magnetic field in the Milky Way galaxy, our position in the Milky Way's galactic disk hinders our attempts at interpreting the observational data. This makes the proposition of "cherchez le champ magnetique" a difficult one to follow. Some recent papers have attempted to fit magnetic field models to spiral galaxies, and in particular to the Milky Way galaxy. Magnetic field reversals in the Milky Way are crucial to all interpretations, be they axisymmetric spiral (ASS) or bisymmetric spiral (BSS) global magnetic field models. Magnetic field reversals can be found in both ASS and BSS magnetic field models, not just BSS ones. The axisymmetric spiral (ASS) magnetic field models produced by the dynamo theory already predict magnetic field reversals, and they are of the type observed in the Milky Way. The small number of magnetic field reversals observed in the Milky Way is compatible with the ASS magnetic field models. The bisymmetric spiral (BSS) magnetic field models as applied to the pulsar RM data and to the QSO and galaxies data have many problems, due to the many pitfalls in model fitting the magnetic field reversals observed in the Milky Way. Many pitfalls are discussed here, including the incomplete comparisons of BSS versus ASS models, the number of spiral arms to be used in modelling, and the proper distance to pulsars via the more accurate distribution of thermal electrons within spiral arms. The two magnetic field reversals in our Milky Way are clearly located in the interarm regions. Predicted magnetic field reversals are periodic, while observed ones are not periodic. Magnetic field reversals cannot be masked effectively by local interstellar magnetised shells. The

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

    NASA Astrophysics Data System (ADS)

    Benard, Pierre

    Nous presentons une etude des fluctuations magnetiques de la phase normale de l'oxyde de cuivre supraconducteur La_{2-x}Sr _{x}CuO_4 . Le compose est modelise par le Hamiltonien de Hubbard bidimensionnel avec un terme de saut vers les deuxiemes voisins (modele tt'U). Le modele est etudie en utilisant l'approximation de la GRPA (Generalized Random Phase Approximation) et en incluant les effets de la renormalisation de l'interaction de Hubbard par les diagrammes de Brueckner-Kanamori. Dans l'approche presentee dans ce travail, les maximums du facteur de structure magnetique observes par les experiences de diffusion de neutrons sont associes aux anomalies 2k _{F} de reseau du facteur de structure des gaz d'electrons bidimensionnels sans interaction. Ces anomalies proviennent de la diffusion entre particules situees a des points de la surface de Fermi ou les vitesses de Fermi sont tangentes, et conduisent a des divergences dont la nature depend de la geometrie de la surface de Fermi au voisinage de ces points. Ces resultats sont ensuite appliques au modele tt'U, dont le modele de Hubbard usuel tU est un cas particulier. Dans la majorite des cas, les interactions ne determinent pas la position des maximums du facteur de structure. Le role de l'interaction est d'augmenter l'intensite des structures du facteur de structure magnetique associees a l'instabilite magnetique du systeme. Ces structures sont souvent deja presentes dans la partie imaginaire de la susceptibilite sans interaction. Le rapport d'intensite entre les maximums absolus et les autres structures du facteur de structure magnetique permet de determiner le rapport U_ {rn}/U_{c} qui mesure la proximite d'une instabilite magnetique. Le diagramme de phase est ensuite etudie afin de delimiter la plage de validite de l'approximation. Apres avoir discute des modes collectifs et de l'effet d'une partie imaginaire non-nulle de la self-energie, l'origine de l'echelle d'energie des fluctuations magnetiques est examinee

  9. Etude des defauts microscopiques et des proprietes optiques, electroniques et magnetiques du compose neodyme cerium oxyde de cuivre

    NASA Astrophysics Data System (ADS)

    Richard, Pierre

    La presente these, qui combine des mesures de diffusion Raman, de transmission infrarouge, de conductivite hyperfrequence et d'interferometrie ultrasonore sur les composes Nd 2-xCexCuO 4, traite des defauts d'oxygene, ainsi que des proprietes optiques, electroniques et magnetiques de ces materiaux. Les resultats experimentaux obtenus sont correles avec plusieurs donnees experimentales disponibles dans la litterature. D'abord, la caracterisation des modes Raman et des niveaux d'energie de champ cristallin de l'ion Nd3+ au moyen de techniques optiques, en fonction du dopage en cerium et du contenu en oxygene, permettent de conclure a la presence de defauts lies a une non-stoechiometrie en oxygene dans ces composes. En effet, des excitations de champ cristallin assignees a des ions Nd3+ en sites irreguliers sont observees, en plus des bandes d'absorption associees aux ions Nd3+ en site regulier, dans les spectres correspondant aux multiplets 4I11/2, 4I13/2 et 4I 15/2 de l'ion Nd3+. Les resultats experimentaux indiquent que, contrairement a la croyance largement repandue, les oxygenes apicaux, bien que presents dans les echantillons dopes, ne sont pas enleves lors du processus de reduction des echantillons necessaire pour faire apparaitre la supraconductivite dans cette famille de cuprates. Au contraire, des lacunes d'oxygene, dont le type varie en fonction du dopage, sont creees lors de ce processus. En particulier, il est montre dans ce travail que la reduction des echantillons dopes de maniere optimale conduit a la creation de lacunes d'oxygene dans les plans CuO2. Les consequences de telles lacunes sont largement discutees. En outre, il est suggere que de telles lacunes sont responsables de la perte de l'ordre antiferromagnetique a longue portee des ions Cu2+. Finalement, l'interaction d'echange anisotrope Nd3+-Cu 2+ dans le compose nondope est caracterisee au moyen de la transmission infrarouge sous champ magnetique. L'eclatement des doublets de Kramers mesure

  10. Synthese de champs sonores adaptative

    NASA Astrophysics Data System (ADS)

    Gauthier, Philippe-Aubert

    La reproduction de champs acoustiques est une approche physique au probleme technologique de la spatialisation sonore. Cette these concerne l'aspect physique de la reproduction de champs acoustiques. L'objectif principal est l'amelioration de la reproduction de champs acoustiques par "synthese de champs acoustiques" ("Wave Field Synthesis", WFS), une approche connue, basee sur des hypotheses de champ libre, a l'aide du controle actif par l'ajout de capteurs de l'erreur de reproduction et d'une boucle fermee. Un premier chapitre technique (chapitre 4) expose les resultats d'appreciation objective de la WFS par simulations et mesures experimentales. L'effet indesirable de la salle de reproduction sur les qualites objectives de la WFS fut illustre. Une premiere question de recherche fut ensuite abordee (chapitre 5), a savoir s'il est possible de reproduire des champs progressifs en salle dans un paradigme physique de controle actif: cette possibilite fut prouvee. L'approche technique privilegiee, "synthese de champs adaptative" ("Adaptive Wave Field Synthesis" [AWFS]), fut definie, puis simulee (chapitre 6). Cette approche d'AWFS comporte une originalite en controle actif et en reproduction de champs acoustiques: la fonction cout quadratique representant la minimisation des erreurs de reproduction inclut une regularisation de Tikhonov avec solution a priori qui vient de la WFS. L'etude de l'AWFS a l'aide de la decomposition en valeurs singulieres (chapitre 7) a permis de comprendre les mecanismes propres a l'AWFS. C'est la deuxieme principale originalite de la these. L'algorithme FXLMS (LMS et reference filtree) est modifie pour l'AWFS (chapitre 8). Le decouplage du systeme par decomposition en valeurs singulieres est illustre dans le domaine du traitement de signal et l'AWFS basee sur le controle independant des modes de rayonnement est simulee (chapitre 8). Ce qui constitue la troisieme originalite principale de cette these. Ces simulations du traitement de signal

  11. LED champing: statistically blessed?

    PubMed

    Wang, Zhuo

    2015-06-10

    LED champing (smart mixing of individual LEDs to match the desired color and lumens) and color mixing strategies have been widely used to maintain the color consistency of light engines. Light engines with champed LEDs can easily achieve the color consistency of a couple MacAdam steps with widely distributed LEDs to begin with. From a statistical point of view, the distributions for the color coordinates and the flux after champing are studied. The related statistical parameters are derived, which facilitate process improvements such as Six Sigma and are instrumental to statistical quality control for mass productions. PMID:26192863

  12. Reliability of CHAMP Anomaly Continuations

    NASA Technical Reports Server (NTRS)

    vonFrese, Ralph R. B.; Kim, Hyung Rae; Taylor, Patrick T.; Asgharzadeh, Mohammad F.

    2003-01-01

    CHAMP is recording state-of-the-art magnetic and gravity field observations at altitudes ranging over roughly 300 - 550 km. However, anomaly continuation is severely limited by the non-uniqueness of the process and satellite anomaly errors. Indeed, our numerical anomaly simulations from satellite to airborne altitudes show that effective downward continuations of the CHAMP data are restricted to within approximately 50 km of the observation altitudes while upward continuations can be effective over a somewhat larger altitude range. The great unreliability of downward continuation requires that the satellite geopotential observations must be analyzed at satellite altitudes if the anomaly details are to be exploited most fully. Given current anomaly error levels, joint inversion of satellite and near- surface anomalies is the best approach for implementing satellite geopotential observations for subsurface studies. We demonstrate the power of this approach using a crustal model constrained by joint inversions of near-surface and satellite magnetic and gravity observations for Maude Rise, Antarctica, in the southwestern Indian Ocean. Our modeling suggests that the dominant satellite altitude magnetic anomalies are produced by crustal thickness variations and remanent magnetization of the normal polarity Cretaceous Quiet Zone.

  13. Gravity Fields from CHAMP Mission Data

    NASA Technical Reports Server (NTRS)

    Lemoine, Frank G.; Luthcke, S. B.; Cox, C. M.; Rowlands, D. D.; Thompson, B. F.; Chinn, D. S.; Williams, T. A.; Nerem, R. S.

    2002-01-01

    The CHAMP mission, launched in July 2000, is the first in a series of missions that will revolutionize our ability to model the Earth s geopotential. The CHAMP spacecraft is equipped for precision tracking by the Global Positioning System (GPS) and Satellite Laser Ranging (SLR) along with a precision accelerometer to provide measurements of the surface forces. Preliminary satellite-only geopotential solutions with only 30 days of CHAMP data are, by some criteria, as strong as solutions made from tracking data collected over the previous 30 years of the space age. Compared to EGM96, CHAMP makes notable contributions in regions where the terrestrial data (surface gravimetry and altimetry) were weak, for example in the polar regions, in the Amazon and the Himalayas. The CHAMP data allow us to separate the geoid from the dynamic ocean topography (DOT) up to at least degree 25 rather than just under degree 20 as in EGM96. We report on satellite-only and combination models that incorporate up to 100 days of CHAMP data as well as other satellite data. We report on our updated processing of the CHAMP tracking and accelerometer data and evaluate the performance of the geopotential models using a variety of tests.

  14. Champ Lyons: An Incomplete Life

    PubMed Central

    Dalton, Martin L.

    2003-01-01

    The life of Champ Lyons, MD, is presented, with emphasis on his tenure as Chairman of the Department of Surgery of the Medical College of Alabama (University of Alabama in Birmingham School of Medicine) from 1950 until 1965. Before becoming chairman Dr. Lyons, as an esteemed microbiologist, participated in the early use of penicillin in wounded servicemen during World War II. Later in his career, he made many contributions to the emerging disciplines of vascular and cardiac surgery. After a brief illness in 1965, Dr. Lyons expired due to a brain tumor. His relatively brief career and his unanticipated sudden demise have lessened the fame of Dr. Lyons to which he is justly entitled. It is the purpose of this presentation to reawaken the surgical community to the importance of this giant of American surgery. PMID:12724636

  15. CHAMP (Camera, Handlens, and Microscope Probe)

    NASA Technical Reports Server (NTRS)

    Mungas, Greg S.; Boynton, John E.; Balzer, Mark A.; Beegle, Luther; Sobel, Harold R.; Fisher, Ted; Klein, Dan; Deans, Matthew; Lee, Pascal; Sepulveda, Cesar A.

    2005-01-01

    CHAMP (Camera, Handlens And Microscope Probe)is a novel field microscope capable of color imaging with continuously variable spatial resolution from infinity imaging down to diffraction-limited microscopy (3 micron/pixel). As a robotic arm-mounted imager, CHAMP supports stereo imaging with variable baselines, can continuously image targets at an increasing magnification during an arm approach, can provide precision rangefinding estimates to targets, and can accommodate microscopic imaging of rough surfaces through a image filtering process called z-stacking. CHAMP was originally developed through the Mars Instrument Development Program (MIDP) in support of robotic field investigations, but may also find application in new areas such as robotic in-orbit servicing and maintenance operations associated with spacecraft and human operations. We overview CHAMP'S instrument performance and basic design considerations below.

  16. CHAMP - Camera, Handlens, and Microscope Probe

    NASA Technical Reports Server (NTRS)

    Mungas, G. S.; Beegle, L. W.; Boynton, J.; Sepulveda, C. A.; Balzer, M. A.; Sobel, H. R.; Fisher, T. A.; Deans, M.; Lee, P.

    2005-01-01

    CHAMP (Camera, Handlens And Microscope Probe) is a novel field microscope capable of color imaging with continuously variable spatial resolution from infinity imaging down to diffraction-limited microscopy (3 micron/pixel). As an arm-mounted imager, CHAMP supports stereo-imaging with variable baselines, can continuously image targets at an increasing magnification during an arm approach, can provide precision range-finding estimates to targets, and can accommodate microscopic imaging of rough surfaces through a image filtering process called z-stacking. Currently designed with a filter wheel with 4 different filters, so that color and black and white images can be obtained over the entire Field-of-View, future designs will increase the number of filter positions to include 8 different filters. Finally, CHAMP incorporates controlled white and UV illumination so that images can be obtained regardless of sun position, and any potential fluorescent species can be identified so the most astrobiologically interesting samples can be identified.

  17. CHAMP Tracking and Accelerometer Data Analysis Results

    NASA Technical Reports Server (NTRS)

    Lemoine, Frank G.; Luthcke, S. B.; Rowlands, D. D.; Pavlis, D. E.; Colombo, O. L.; Ray, Richard D.; Thompson, B.; Nerem, R. S.; Williams, Teresa A.; Smith, David E. (Technical Monitor)

    2002-01-01

    The CHAMP (Challenging Minisatellite Payload) mission's unique combination of sensors and orbit configuration will enable unprecedented improvements in modeling and understanding the Earth's static gravity field and its temporal variations. CHAMP is the first of two missions (GRACE (Gravity Recovery and Climate Experiment) to be launched in the later part of '01) that combine a new generation of GPS (Global Positioning System) receivers, a high precision three axis accelerometer, and star cameras for the precision attitude determination. In order to isolate the gravity signal for science investigations, it is necessary to perform a detailed reduction and analysis of the GPS and SLR tracking data in conjunction with the accelerometer and attitude data. Precision orbit determination based on the GPS and SLR (Satellite Laser Ranging) tracking data will isolate the orbit perturbations, while the accelerometer data will be used to distinguish the surface forces from those due to the geopotential (static, and time varying). In preparation for the CHAMP and GRACE missions, extensive modifications have been made to NASA/GSFC's GEODYN orbit determination software to enable the simultaneous reduction of spacecraft tracking (e.g. GPS and SLR), three axis accelerometer and precise attitude data. Several weeks of CHAMP tracking and accelerometer data have been analyzed and the results will be presented. Precision orbit determination analysis based on tracking data alone in addition to results based on the simultaneous reduction of tracking and accelerometer data will be discussed. Results from a calibration of the accelerometer will be presented along with the results from various orbit determination strategies. Gravity field modeling status and plans will be discussed.

  18. CHAMP Magnetic Anomalies of the Antarctic Crust

    NASA Technical Reports Server (NTRS)

    Kim, Hyung Rae; Gaya-Pique, Luis R.; vonFrese, Ralph R. B.; Taylor, Patrick T.; Kim, Jeong Woo

    2003-01-01

    Regional magnetic signals of the crust are strongly masked by the core field and its secular variations components and hence difficult to isolate in the satellite measurements. In particular, the un-modeled effects of the strong auroral external fields and the complicated- behavior of the core field near the geomagnetic poles conspire to greatly reduce the crustal magnetic signal-to-noise ratio in the polar regions relative to the rest of the Earth. We can, however, use spectral correlation theory to filter the static lithospheric and core field components from the dynamic external field effects. To help isolate regional lithospheric from core field components, the correlations between CHAMP magnetic anomalies and the pseudo magnetic effects inferred from gravity-derived crustal thickness variations can also be exploited.. Employing these procedures, we processed the CHAMP magnetic observations for an improved magnetic anomaly map of the Antarctic crust. Relative to the much higher altitude Orsted and noisier Magsat observations, the CHAMP magnetic anomalies at 400 km altitude reveal new details on the effects of intracrustal magnetic features and crustal thickness variations of the Antarctic.

  19. La genèse du concept de champ quantique

    NASA Astrophysics Data System (ADS)

    Darrigol, O.

    This is a historical study of the roots of a concept which has proved to be essential in modern particle physics : the concept of quantum field. The first steps were accomplished by two young theoreticians : Pascual Jordan quantized the free electromagnetic field in 1925 by means of the formal rules of the just discovered matrix mechanics, and Paul Dirac quantized the whole system charges + field in 1927. Using Dirac's equation for electrons (1928) and Jordan's idea of quantized matter waves (second quantization), Werner Heisenberg and Wolfgang Pauli provided in 1929-1930 an extension of Dirac's radiation theory and the proof of its relativistic invariance. Meanwhile Enrico Fermi discovered independently a more elegant and pedagogical formulation. To appreciate the degree of historical necessity of the quantization of fields, and the value of contemporaneous critics to this approach, it was necessary to investigate some of the history of the old radiation theory. We present the various arguments however provisional or naïve or wrong they could be in retrospect. So we hope to contribute to a more vivid picture of notions which, once deprived of their historical setting, might seem abstruse to the modern user. Nous présentons une étude historique des origines d'un concept devenu essentiel dans la physique moderne des particules : le concept de champ quantique. Deux jeunes théoriciens franchirent les premières étapes : Pascual Jordan quantifia le champ électromagnétique en 1925 grâce aux règles formelles de la mécanique des matrices naissante, et Paul Dirac quantifia le système complet charges + champ en 1927. Au moyen de l'équation de l'électron de Dirac (1928) et de l'idée de Jordan d'ondes de matière quantifiées (deuxième quantification), Werner Heisenberg et Wolfgang Pauli donnèrent en 1929-1930 une extension de la théorie du rayonnement de Dirac et la preuve de son invariance relativiste. Pendant ce temps Enrico Fermi découvrit ind

  20. Preliminary Results From the Champ Occultation Measurements

    NASA Astrophysics Data System (ADS)

    Hajj, G.; Dong, D.; Iijima, B.; Kuang, D.; Kursinski, R.; Mannucci, A.; Meehan, T.; Romans, L.; de la Torre Juárez, M.; Yunck, T.

    2001-05-01

    Champ collects 200-250 globally distributed GPS occultations every day providing a wealth of information on atmospheric parameters such as pressure, temperature, humidity between 0-60 km altitude and electron density above 60 km altitude. There are several aspects to the Champ occultation measurements which distinguish them from prior measurements (such as from GPS/MET, Oersted and SAC-C): (1) They are taken during solar maximum; (2) they are collected with a new generation receiver ("BlackJack") which provides high quality L1 and L2 measurements even when the DoD anti-spoofing of the GPS signal is turned on; (3) the tracking loop in the receiver is optimized to allow the occulted signal to descend very low in the atmosphere (<1km from the surface). A further distinction comes from the fact that selective availability (the dithering of the GPS clocks) was permanently turned off by DoD, therefore reducing or eliminating the need for 1-second ground measurements previously used to difference out high frequency GPS clock drifts. This talk will present results obtained at JPL from the early Champ occultation data sets, first collected in February, 2001, and will address the specific issues listed above. Specifically, we will present (a) statistics on how low in the atmosphere occultations are able to probe as a function of geographical latitudes and humidity conditions; (b) the limitations on higher altitude atmospheric retrievals (between 30-60 km) caused by the ionosphere at different local times and solar conditions, including comparisons to GPS/MET data taken during solar minimum; (c) individual and statistical comparisons of temperature and water vapor to atmospheric analyses such as NCEP and ECMWF and other data sets such as radiosondes; (d) the impact of including or excluding high rate ground data.

  1. Champ - From Data Acquisition To Innovative Services

    NASA Astrophysics Data System (ADS)

    Ritschel, B.; Champ-Isdc Team

    To understand the complex system earth and its interchange and interaction processes with the atmosphere a complete digital data basis is an essential requirement. The whole digital data basis consists of distributed and validated data bases wich are con- nected via a world-wide network. Online information systems like the CHAMP-ISDC with its clearinghouse and datawarehouse services allow an aimed search for required data and information. Excellent geoscientific applications using clearinghouse and datawarehouse features make for relevant geoscientific, economic and social services.

  2. Changements climatiques et variations du champ magnetique terrestre dans le sud de la Patagonie (Argentine) depuis 51 200 ans reconstitues a partir des proprietes magnetiques des sediments du lac Laguna Potrok Aike

    NASA Astrophysics Data System (ADS)

    Lise-Pronovost, Agathe

    Rock magnetism is influenced by climate and by the Earth's magnetic field. The goal of this thesis is to use the rock magnetic properties of the long sedimentary sequence from the lake Laguna Potrok Aike (106 m, 51200 cal BP) to derive paleomagnetic and paleoclimatic records in a key area of the Southern Hemisphere that is poorly documented. Laguna Potrok Aike (52°S, 70°W) is located in southeastern Patagonia (Argentina) in the path of the strong Southern Hemisphere westerly winds and in the source area of the dust deposited in Antarctica during Glacial periods. The lake geographical location is therefore ideal to reconstruct past changes in aeolian activity and climate changes in Patagonia. It is also a key location to reconstruct past changes of the geomagnetic field because the Southern Hemisphere is significantly under-documented relative to the Northern Hemisphere. In addition, the proximity of the South Atlantic Anomaly (SAA) as well as the Southern Hemisphere high flux lobes could allow identifying differences in the paleomagnetic field evolution in southern South America relative to the much more documented Northern Hemisphere. For his strong potential to provide high-resolution climatic, aeolian and paleomagnetic records beyond the last climatic transition, the maar lake Laguna Potrok Aike was drilled in the framework of the International scientific Continental Drilling Program (ICDP) for the Potrok Aike maar lake Sediment Archive Drilling prOject (PASADO). In this thesis, high-resolution rock-magnetic and physical properties are used in order to reconstruct paleoclimate and paleomagnetic records from the southernmost part of South America. In the first chapter, the full-vector paleomagnetic record (inclination, declination and relative paleointensity) derived from the sediments of Laguna Potrok Aike. A grain size influence on the relative paleointensity record (NRM/ARM) was corrected using the median destructive field of the natural remanent magnetisation (MDFNRM). Full-vector comparison of the new paleomagnetic record with other records from southern South America, elsewhere in the Southern Hemisphere, as well as dipole field models and compilations reveal similar millennial-scale variability. The Laschamp geomagnetic excursion and possibly the Mono Lake as well as the Hilina Pali excursions are recorded and suggest the global nature of these events. Nevertheless comparison with the Lake Baikal and Biwa records located on the opposite side of the globe in Siberia and Japan respectively reveals a different behaviour at ca. 46000 cal BP in Laguna Potrok Aike and in southern South America, hinting at a non-dipolar origin. In the second chapter, rock-magnetic proxies of dust and wind intensity since 51200 cal BP are constructed. The combined use of rock magnetism and grain size data allowed identifying the median destructive field of the isothermal remanent magnetisation (MDFIRM) as best reflecting silt-sized magnetite typically transported by wind in suspension over short distances. The MDF IRM displays similar variability than other wind intensity proxies derived from marine and lacustrine sediments, peat bug and speleothem records from Patagonia since the last climatic transition and from the Southern Hemisphere since 51200 cal BP. In addition, estimation of the flux of magnetite to the lake, investigation of the grain size influence on magnetic susceptibility and comparison with distal Patagonian dust records from the Southern Ocean and Antarctica indicate that the magnetic susceptibility signal from Laguna Potrok Aike is a dust record at the multi-millennial scale. In the third chapter, rock-magnetic proxies of runoff events associated with extreme precipitation and permafrost melt since 51200 cal BP are presented. The runoff events are identified by the presence of high coercivity magnetic mineral (such as hematite and goethite) which its pedogenic origin is inferred from geological, limnological, stratigraphic and climatic evidence. The runoff events are generally associated with mass movement deposits during time of enhanced lake productivity in Laguna Potrok Aike and are also coeval within the limit of the chronology to warm atmospheric conditions recorded in Antarctica. In addition, we show that the authigenic formation of iron sulfide such as greigite is strictly associated to reworked sands and tephra layers providing the required suboxic conditions and dissolved sulfate. As a whole, rock magnetism of the sediment from Laguna Potrok Aike provides a high quality full-vector paleomagnetic record as well as rock-magnetic proxies of past climate changes in southeastern Patagonia that are also associated with climate changes in Antarctica. Keywords: [Paleomagnetism, sediment magnetism, paleoclimatology, Laguna Potrok Aike, Patagonia, Southern Hemisphere, millennial- to centennial-scale variability, last Glacial period, Holocene, wind intensity].

  3. ChaMP Serendipitous Galaxy Cluster Survey

    SciTech Connect

    Barkhouse, Wayne A.; Green, P.J.; Vikhlinin, A.; Kim, D.-W.; Perley, D.; Cameron, R.; Silverman, J.; Mossman, A.; Burenin, R.; Jannuzi, B.T.; Kim, M.; Smith, M.G.; Smith, R.C.; Tananbaum, H.; Wilkes, B.J.; /Harvard-Smithsonian Ctr. Astrophys. /UC, Berkeley, Astron. Dept. /SLAC /Garching, Max Planck Inst., MPE /Moscow, Space Res. Inst. /NOAO, Tucson /Cerro-Tololo InterAmerican Obs.

    2006-04-03

    We present a survey of serendipitous extended X-ray sources and optical cluster candidates from the Chandra Multi-wavelength Project (ChaMP). Our main goal is to make an unbiased comparison of X-ray and optical cluster detection methods. In 130 archival Chandra pointings covering 13 square degrees, we use a wavelet decomposition technique to detect 55 extended sources, of which 6 are nearby single galaxies. Our X-ray cluster catalog reaches a typical flux limit of about {approx} 10{sup -14} erg s{sup -1} cm{sup -2}, with a median cluster core radius of 21''. For 56 of the 130 X-ray fields, we use the ChaMP's deep NOAO/4m MOSAIC g', r', and i' imaging to independently detect cluster candidates using a Voronoi tessellation and percolation (VTP) method. Red-sequence filtering decreases the galaxy fore/background contamination and provides photometric redshifts to z {approx} 0.7. From the overlapping 6.1 square degree X-ray/optical imaging, we find 115 optical clusters (of which 11% are in the X-ray catalog) and 28 X-ray clusters (of which 46% are in the optical VTP catalog). The median redshift of the 13 X-ray/optical clusters is 0.41, and their median X-ray luminosity (0.5-2 keV) is L{sub X} = (2.65 {+-} 0.19) x 10{sup 43} ergs s{sup -1}. The clusters in our sample that are only detected in our optical data are poorer on average ({approx} 4{sigma}) than the X-ray/optically matched clusters, which may partially explain the difference in the detection fractions.

  4. Gravity Models from CHAMP and other Satellite Data

    NASA Technical Reports Server (NTRS)

    Lemoime, Frank G.; Cox, C. M.; Chinn, D. S.; Zelensky, N. P.; Thompson, B. F.; Rowlands, D. D.; Luthdke, S. B.; Nerem, R. S.

    2003-01-01

    CHAMP spacecraft is the first of a series of new spacecraft missions that are revolutionizing our ability to model the Earth's geopotential. We report on the analysis of over 100 days of CHAMP data in 2001 and 2002, merged with tracking data of other satellites such as Jason, Topex, GFO, Starlette, Stella, Spot-2, as well as satellite altimetry. We find that the CHAMP-only component of these solutions is a significant improvement over pre-CHAMP satellite only models with respect to the high degree information expressed by the geopotential model coefficients. For example, the variance of the differences with altimeter-derived anomalies through degree 70 is 2.80 mGal(sup 2) for the CHAMP-only solution based on 87 days of data vs. 10.19 mGal(sup 2) for EGM96S. Nonetheless, in order to model properly the various resonances to which different satellites are sensitive, we must include other satellite data. We evaluate the performance of these new CHAMP derived solutions with EGM96 and the EIGEN series of solutions. We review carefully the performance of these models for altimetric satellites.

  5. An Assessment of Gravity Recovery with CHAMP Data

    NASA Technical Reports Server (NTRS)

    Lemoine, F. G.; Luthcke, S. B.; Rowlands, D. D.; Cox, C. M.; Chinn, D. S.; Pavlis, D. E.; Thompson, B.; Nerem, R. S.; Ray, R.; Chao, Benjamin F. (Technical Monitor)

    2002-01-01

    The CHAMP mission, launched in July 2000, is the first in the series of mapping missions for the Earth's geopotential scheduled for the first decade of the new millenium. Its unique contributions compared to all the previous generation of satellites whose data have been included in Earth geopotential models are the precision global tracking with GPS data, and the availability of precision accelerometry data to model the nonconservative forces. Over the past year we have implemented extensive modifications to our GEODYN orbit determination processing code and ancillary data preprocessors to process the GPS and accelerometry data from missions such as CHAMP and GRACE. We report on the analysis of up to 60 days of CHAMP data and how these data contribute to Earth geopotential solutions where the base model is a derivative of EGM96. Preliminary results with only 12.5 days of data processed clearly show the ability of the CHAMP data to improve the modeling of the zonals (1=10 to 40), the m-dailies, the primary resonance terms, and the sectoral harmonics. We will detail the results of our calibrations of the CHAMP accelerometry and assess the quality of test solutions that include these CHAMP data.

  6. Etude de l'influence du champ magnetique dans une section d'essais thermohydraulique d'un canal de reacteur nucleaire CANDU 6

    NASA Astrophysics Data System (ADS)

    Landry-Lavoie, Renaud

    This memoir deals with the effects of the magnetic fields present in a thermal hydraulic test section of the Canadian nuclear industry. This test section is used to determine the thermal hydraulic conditions that can lead to critical heat flux in a channel of a CANDU 6 nuclear reactor. To perform their series of experiments the STERN Company used strong electric currents to heat the simulation bundles with a thermal power similar to the one found in a channel of a CANDU reactor. The materials constituting the simulation channel and its supports are of ferromagnetic nature. The strong magnetic field generated by the bundles implies that they are subjected to a magnetostatic force due to the magnetization of the ferromagnetic materials. The nuclear industry wants to know if these efforts, combined with the force of gravity, are sufficient to maintain the bundles in place in the simulation channel. The question also arises whether or not the magnetic field present in the channel can affect the parameters of boiling heat transfer. To determine the magnetic field distribution in the simulation channel, we had recourse to the magnetostatic image method and the integral method of calculation of magnetization. The results of the calculations show that the magnetostatic forces exerted by the ferromagnetic elements of the test section are inferior in magnitude to the one estimated by the STERN laboratorie. We used the mechanistic model of Sullivan et al. (1964) to evaluate the possible influence of the magnetic fields on the departure diameter of the vapor bubbles. The deviation in the frequency of bubble emission was evaluated by using the correlations of Zuber et al. (1959) and Cole (1960). By introducing a magnetostatic force in the boiling model and in the correlations, we demonstrated that the magnetic field present in the STERN test section has a negligible effect on the bubble departure diameter and their emission frequency. We conclude that the conditions in the test section are consistent with those prevailing in the channel of a CANDU 6 reactor.

  7. Combining human and machine processes (CHAMP)

    NASA Astrophysics Data System (ADS)

    Sudit, Moises; Sudit, David; Hirsch, Michael

    2015-05-01

    Machine Reasoning and Intelligence is usually done in a vacuum, without consultation of the ultimate decision-maker. The late consideration of the human cognitive process causes some major problems in the use of automated systems to provide reliable and actionable information that users can trust and depend to make the best Course-of-Action (COA). On the other hand, if automated systems are created exclusively based on human cognition, then there is a danger of developing systems that don't push the barrier of technology and are mainly done for the comfort level of selected subject matter experts (SMEs). Our approach to combining human and machine processes (CHAMP) is based on the notion of developing optimal strategies for where, when, how, and which human intelligence should be injected within a machine reasoning and intelligence process. This combination is based on the criteria of improving the quality of the output of the automated process while maintaining the required computational efficiency for a COA to be actuated in timely fashion. This research addresses the following problem areas: • Providing consistency within a mission: Injection of human reasoning and intelligence within the reliability and temporal needs of a mission to attain situational awareness, impact assessment, and COA development. • Supporting the incorporation of data that is uncertain, incomplete, imprecise and contradictory (UIIC): Development of mathematical models to suggest the insertion of a cognitive process within a machine reasoning and intelligent system so as to minimize UIIC concerns. • Developing systems that include humans in the loop whose performance can be analyzed and understood to provide feedback to the sensors.

  8. Project CHAMP, 1985-1986. OEA Evaluation Report.

    ERIC Educational Resources Information Center

    New York City Board of Education, Brooklyn. Office of Educational Assessment.

    The Chinese Achievement and Mastery program, Project CHAMP, was a bilingual (Chinese/English) project offered at three high schools in Manhattan. The major goals were to enable Chinese students of limited English proficiency (LEP) to learn English and to master content in mathematics, science, global history, computer mathematics, and native…

  9. Validation of 1 Year of Champ Radio Occultation Data

    NASA Astrophysics Data System (ADS)

    Marquardt, C.; Schöllhammer, K.; Schroedter, M.; Tomassini, M.; Beyerle, G.; Schmidt, T.; Wickert, J.; König, R.; Grunwaldt, L.; Reigber, Ch.

    The German polar-orbiting satellite CHAMP (Challenging mini-satellite Payload) was successfully launched in mid-2000. Equipped with a space borne GPS (Global Posi- tioning System) receiver provided by JPL (Jet Propulsion laboratory), CHAMP ex- ploits the signals of the global constellation of GPS satellites for the remote sensing of temperature and humidity in the atmosphere. This new remote sensing technique provides globally distributed, calibration free and weather independent measurements with - thanks to its limb geometry - high vertical resolution. In contrast to the earlier US proof-of-concept mission GPS/MET, CHAMP exhibits improved technical char- acteristics of the instrument and aims at quasi-continuous operation. Since its first successful radio occultation sounding in February 2001, CHAMP col- lected more than 40000 individual profiles of temperature and tropospheric moisture. By now, several multi-week periods of continuous measurements are available for all seasons, each one providing up to 200 daily soundings. We present a validation study of this data set against operational meteorological anal- yses, the global radiosonde network, and retrievals obtained from the ATOVS fam- ily of instruments (AMSU-A, AMSU-B, and HIRS) on board NOAA-16 for both stratospheric temperatures and tropospheric moisture. The performance of the pro- cessing system for strongly disturbed atmospheric conditions like those during the stratospheric major warming events in the early winter 2001/2002 will be addressed.

  10. Recent Results from CHAMP Tracking and Accelerometer Data Analysis

    NASA Technical Reports Server (NTRS)

    Luthcke, S. B.; Rowlands, D. D.; Lemoine, F. G.; Nerem, R. S.; Thompson, B.; Pavlis, E.; Williams, T. A.; Colombo, O. L.; Chao, Benjamin F. (Technical Monitor)

    2002-01-01

    The CHAMP mission's unique combination of sensors and orbit configuration will enable unprecedented improvements in modeling and understanding the Earth's static gravity field and its temporal variations. CHAMP is the first of two missions (GRACE to be launched in the early part of 02') that combine a new generation of Global Positioning System (GPS) receivers, a high precision three-axis accelerometer, and star cameras for the precision attitude determination. In order to isolate the gravity signal for science investigations, it is necessary to perform a detailed reduction and analysis of the GPS and Satellite Laser Ranging (SLR) tracking data in conjunction with the accelerometer and attitude data. Precision orbit determination based on the GPS and SLR tracking data will isolate the orbit perturbations, while the accelerometer data will be used to distinguish the non-gravitational forces from those due to the geopotential (static, and time varying). In preparation for the CHAMP and GRACE missions, extensive modifications have been made to NASA/GSFC's GEODYN orbit determination software to enable the simultaneous reduction of spacecraft tracking (e.g. GPS and SLR), three-axis accelerometer and precise attitude data. Several weeks of CHAMP tracking and accelerometer data have been analyzed and the results will be presented. Precision orbit determination analysis based on tracking data alone in addition to results based on the simultaneous reduction of tracking and accelerometer data will be discussed. Results from a calibration of the accelerometer will be presented along with the results from various orbit determination strategies.

  11. Atmosphere sounding by GPS radio occultation: First results from CHAMP

    NASA Astrophysics Data System (ADS)

    Wickert, Jens; Reigber, Christoph; Beyerle, Georg; König, Rolf; Marquardt, Christian; Schmidt, Torsten; Grunwaldt, Ludwig; Galas, Roman; Meehan, Thomas K.; Melbourne, William G.; Hocke, Klemens

    The first radio occultation measurements of the CHAMP (CHAllenging Minisatellite Payload) satellite using Global Positioning System (GPS) signals have been performed on February 11, 2001. By the end of April 2001 more than 3000 occultations were recorded. Globally distributed vertical profiles of dry temperature and specific humidity are derived, of which a set of 438 vertical dry temperature profiles is compared with corresponding global weather analyses. The observed temperature bias is less than ∼1 K above the tropopause and even less than 0.5 K in the altitude interval from 12 to 20 km at latitudes >30°N. About 55% of the compared profiles reached the last kilometer above the Earth's surface. In spite of the activated anti-spoofing mode of the GPS system the state-of-the-art GPS flight receiver aboard CHAMP combined with favorable antenna characteristics allows for atmospheric sounding with high accuracy and vertical resolution.

  12. Photoelectron Emission and Lyman Alpha Measurements by the CHAMPS Rockets

    NASA Astrophysics Data System (ADS)

    Sternovsky, Z.; Robertson, S. H.; Dickson, S.; Gausa, M. A.; Friedrich, M.; Horanyi, M.

    2012-12-01

    The daytime CHAMPS (CHarge And mass of Meteoritic smoke ParticleS) sounding rocket carried a suit of instruments for the monitoring of photoemission current and Lyman alpha flux as a function of altitude. The results show that photoemission is significant down to 60-75 km altitude, depending on the photo-emitting surface. Lyman alpha was detected to about 65 km altitude. The daytime CHAMPS rocket launched on 13 October 13:50 UT from the Andøya Rocket Range, Norway. The CHAMPS instruments detected layers of particles, probably of meteoric origin, charged both positive and negative in the 63-93 km altitude range. The CHAMPS payloads were also designed to characterize the plasma environment and thus also carried Faraday rotation antennas and electron and ion probes. Solar UV plays an important role in charge balance for both the rocket body and meteoric smoke particles. Photoelectron emission was monitored by a set of three detectors consisting of an emitting surface (Platinum, Aluminum and Zirconium) biased at -10 V and placed behind a fine grid. The Al and Zr surfaces produced similar signals with photoemission measureable above 75 km altitude. The Pt surface emitted photoelectrons even below 60 km altitude. The different behavior of Pt can possibly be due to exposure to atomic oxygen, though further analysis is necessary. The solar Lyman alpha radiation was measured by a UV photodiode placed behind a pair or filters to reduce the contribution to the signal from visible light. Lyman alpha was detected down to 65 km altitude, which confirms that photo-detachment and photoelectric charging needs to be considered for the charge balance of particle layers in the mesosphere region. All instruments were calibrated at the facilities of the Laboratory for Atmospheric and Space Physics at the University of Colorado.

  13. Comparison of ionospheric radio occultation CHAMP data with IRI 2000

    NASA Astrophysics Data System (ADS)

    Jakowski, N.; Wehrenpfennig, A.; Tsybulya, K.

    The GPS radio occultations measured on board low Earth orbiting satellites provide vertical electron density profiles of the ionosphere from satellite orbit heights down to the bottomside. No other profiling technique unifies profiling through the entire F2 layer with global coverage. First results of ionospheric radio occultation (IRO) measurements carried out onboard the German CHAMP satellite mission agree with vertical sounding based F2 layer height and electron density estimations within 13% and 17% RMS deviation. Methods and algorithms applied for retrieving the electron density profiles through the F2 layer are addressed. Although the validation of the CHAMP IRO data has still to be completed, we present a systematic comparison of more than 15000 IRO derived electron density profiles with corresponding IRI 2000 estimations. The results are discussed for quite different geophysical conditions, e.g. as a function of local time, season, geomagnetic/geographic latitude, level of geomagnetic activity. For a limited umber of events both types of electron density profiles are compared with independent electron density data obtained from vertical sounding stations on Earth and from the Langmuir probe onboard CHAMP.

  14. Cross-Cultural Adaptation of the CHAMPS Questionnaire in French Canadians with COPD

    PubMed Central

    Mak, Susanne; Soicher, Judith E.; Mayo, Nancy E.; Wood-Dauphinee, Sharon; Bourbeau, Jean

    2016-01-01

    Physical activity is difficult to measure in individuals with COPD. The Community Healthy Activities Model Program for Seniors (CHAMPS) questionnaire demonstrated strong clinometric properties when used with the elderly and with those affected by chronic disease. Study objectives were to translate, culturally adapt the CHAMPS into French, and reexamine its test-retest reliability and construct validity in French and English Canadians with COPD. This paper presents the cross-cultural adaptation of the CHAMPS; results of its clinometric testing will be described in another article. The CHAMPS examines the degree of physical activity performed in a typical week through two summary scales, caloric expenditure and activity frequency. The CHAMPS was only in English; thus, a cross-cultural adaptation was needed to translate the CHAMPS into French for use in French Canadians with COPD. Cross-cultural adaptation consisted of forward and back translation, with expert review at each stage of translation: minor inconsistencies were uncovered and rectified. Five French participants with COPD completed the finalized Canadian French CHAMPS and participated in cognitive debriefing; no problematic items were identified. A structured and stepwise, cross-cultural adaptation process produced the Canadian French CHAMPS, with items of equivalent meaning to the English version, for use in French Canadians with COPD. PMID:27445570

  15. Cross-Cultural Adaptation of the CHAMPS Questionnaire in French Canadians with COPD.

    PubMed

    Mak, Susanne; Soicher, Judith E; Mayo, Nancy E; Wood-Dauphinee, Sharon; Bourbeau, Jean

    2016-01-01

    Physical activity is difficult to measure in individuals with COPD. The Community Healthy Activities Model Program for Seniors (CHAMPS) questionnaire demonstrated strong clinometric properties when used with the elderly and with those affected by chronic disease. Study objectives were to translate, culturally adapt the CHAMPS into French, and reexamine its test-retest reliability and construct validity in French and English Canadians with COPD. This paper presents the cross-cultural adaptation of the CHAMPS; results of its clinometric testing will be described in another article. The CHAMPS examines the degree of physical activity performed in a typical week through two summary scales, caloric expenditure and activity frequency. The CHAMPS was only in English; thus, a cross-cultural adaptation was needed to translate the CHAMPS into French for use in French Canadians with COPD. Cross-cultural adaptation consisted of forward and back translation, with expert review at each stage of translation: minor inconsistencies were uncovered and rectified. Five French participants with COPD completed the finalized Canadian French CHAMPS and participated in cognitive debriefing; no problematic items were identified. A structured and stepwise, cross-cultural adaptation process produced the Canadian French CHAMPS, with items of equivalent meaning to the English version, for use in French Canadians with COPD.

  16. Élimination du bore du silicium par plasma inductif sous champ électrique

    NASA Astrophysics Data System (ADS)

    Combes, R.; Morvan, D.; Picard, G.; Amouroux, J.

    1993-05-01

    We analyzed purification mechanisms of silicon by inductive plasma with a fluoride slag. The aim is to study boron elimination from doped electronic grade silicon in function of the nature of the slag to obtain a photovoltaic grade silicon. The steady began with the calculation and the comparison of the stability diagram of boron compounds in presence of CaF2, BaF2 and MgF2. This study led us to conclude that BaF2 is the better slag for silicon purification. This has been confirmed by experience. In a second time, we made purifications under electric bias to enhance slag efficiency. We noticed that BaF2 is more sensitive to electric bias than other slags. Nous avons analysé le mécanisme de purification du silicium sous plasma inductif en présence d'un laitier fluoré. L'objectif principal est d'étudier l'élimination du bore du silicium électronique dopé en fonction de la nature du fluorure pour obtenir un silicium de qualité photovoltaïque. L'étude a commencé par l'établissement et la comparaison de diagrammes des composés du bore en présence de CaF2, de MgF2 et de BaF2. Nous avons déduit de cette première étude que BaF2 est le meilleur laitier pour la purification du silicium. Ceci a été corroboré par l'expérience. Nous avons ensuite opéré en présence d'un champ électrique dans le but d'améliorer encore l'efficacité des laitiers. Nous avons constaté que BaF2 est plus sensible au champ électrique que les deux autres laitiers utilisés.

  17. Recent results from CHAMP plasma parameter and magnetic field observations

    NASA Astrophysics Data System (ADS)

    Stolle, Claudia; Luehr, Hermann; Park, Jaeheung; Xiong, Chao; Fejer, B. G.

    The multi-year data base of magnetic field and ionospheric measurements from the CHAMP satellite contains an enormous potential to investigate the behaviour and the origin of currents in the F region. Very prominent phenomena are the post-sunset equatorial plasma irregularities (commonly known as "bubbles", or "Equatorial Spread-F" (ESF)) which cause also signatures in the total magnetic field due to diamagnetic currents. The continuous magnetic observations, available at a 1Hz rate, have allowed for the compilation of a comprehensive climatology of the magnetic signatures due to ESF. It reveals a distinct seasonal/longitudinal (S/L) distribution, and the occurrence rate reduces considerably with decreasing solar flux. The (S/L) distribution of bubbles has been found to correlate very well, up to 90 percent, with the pre-reversal enhancement vertical plasma drift peak. This provides strong evidence for the close relation between these phenomena. Since the amplitude of the diamagnetic effect depends on the ambient magnetic field strength and on the background electron density, the global distribution shows also slight differences to the ESF climatology based on plasma depletions. Although electron density readings are only available every 15s, CHAMP data suggest that the plasma irregularities are less structured at places where the ambient magnetic field is strong (e.g. East Asia, Indonesia). In these regions the bubble statistic based on magnetic signatures is systematically lower than that from plasma measurements.

  18. Determination of the orbit of the CHAMP satellite based on the laser observations

    NASA Astrophysics Data System (ADS)

    Lejba, P.

    This work presents the results of orbit determination of the CHAMP satellite from observations of 14 the best SLR stations for year 2002 All computations were based on the Earth combined gravity field model EIGEN-CG01C Reigber et al 2005 In computations was taken the orbital programme GEODYN-II created and accesibled by NASA The got RMS value of the orbit of the CHAMP satellite is better than 30 cm The obtained results show that the orbit of the CHAMP satellite is highly perturbed by the Earth s gravity field and by the atmosphere of the Earth

  19. Sporadic E Morphology from GPS-CHAMP Radio Occultation

    NASA Technical Reports Server (NTRS)

    Wu, Dong L.; Ao, Chi O.; Hajj, George A.; de la Torre Juarez, Manuel; Mannucci, Anthony J.

    2005-01-01

    The scintillations of phase and amplitude in terms of signal-to-noise ratio (SNR) of the GPS radio occultation signal are caused by thin ionization layers. These thin irregular electron density layers in the E region ionosphere are often called sporadic E (Es). For a monthly retrieval of Es morphology we use the variances of the phase and SNR fluctuations of worldwide 6000 GPS/CHAMP occultations in the E region. The Es climatology is studied globally with the SNR and phase variances in terms of monthly zonal means, seasonal maps, and diurnal and long-term variations. The zonal mean variances reveal strong, extended Es activities at summertime midlatitudes but weak, confined activities in wintertime high latitudes, peaking at 105 km. Global maps at 105-km altitude show clear dependence of Es activities on the geomagnetic dip angle, where the summertime midlatitude Es occurs mostly at dip angles of 30 deg. - 60 deg. and the wintertime high-latitude enhancement occurs mostly at dip angles greater than 80 deg. The midlatitude Es variances exhibit a strong semidiurnal variation with peak hours near 0800 1000 and 2000 local solar time, respectively. The peak hours are delayed slightly with decreasing height, suggesting influences from the semidiurnal tide. To provide more insights on the observed SNR and phase variances, we model radio wave propagation for the CHAMP observing geometry under several perturbed cases in the E region ionosphere. The model simulations indicate that the SNR variance has the maximum response to Es perturbations at vertical wavelengths of 1.2 km, whereas the phase response maximizes at 2 km (for the 1-s variance analysis). The characteristic scale depends little on the truncation time used in the SNR variance analysis, but it increases with the truncation time for the phase variances. Initial studies show that reasonable global Es morphology can be produced on a monthly and seasonal basis with the CHAMP one-antenna occultations. Better results

  20. Temperature Effects on the Features of the CHAMP Vector Magnetometer

    NASA Astrophysics Data System (ADS)

    Yin, Fan; Ma, Shuying; Luehr, Hermann; Rauberg, Jan

    2015-04-01

    CHAMP (CHAllenging Minisatellite Payload), a German small satellite mission to study the Earth's gravity field, magnetic field and upper atmosphere, ended in space on 19 September 2010. Thanks to the good quality of the satellite and to several altitude maneuvers, the satellite provided continuous and reliable observations including house-keeping data at different processing levels for more than 10 years. By processing the data of FGM (FluxGate vector Magnetometer), some effects of temperature on the FGM performance have been unfolded. The scale factors of the FGM show a positive correlation with the sensor temperature and the offsets show both positive and negative correlation. The 8 Hz disturbances from FGM x channel are temperature dependent and suppressed at higher temperature. It is very interesting that the noise power of the magnetometer has a larger magnitude at lower temperature rather than at higher temperature.

  1. Effect of Varying Crustal Thickness on CHAMP Geopotential Data

    NASA Technical Reports Server (NTRS)

    Taylor, P. T.; Kis, K. I.; vonFrese, R. R. B.; Korhonen, J. V.; Wittmann, G.; Kim, H. R.; Potts, L. V.

    2003-01-01

    To determine the effect of crustal thickness variation on satellite-altitude geopotential anomalies we compared two regions of Europe with vastly different values, Central/Southern Finland and the Pannonian Basin. Crustal thickness exceeds 62 km in Finland and is less than 26 km in the Pannonian Basin. Heat-flow maps indicate that the thinner and more active crust of the Pannonian Basin has a value nearly three times that of the Finnish Svecofennian Province. Ground based gravity mapping in Hungary shows that the free-air gravity anomalies across the Pannonian Basin are near 0 to +20 mGal with shorter wavelength anomalies from +40 to less than +60 mGal and some 0 to greater than -20 mGal. Larger anomalies are detected in the mountainous areas. The minor value anomalies can indicate the isostatic equilibrium for Hungary (the central part of the Pannonian Basin). Gravity data over Finland are complicated by de-glaciation. CHAMP gravity data (400 km) indicates a west-east positive gradient of greater than 4 mGal across Central/Southern Finland and an ovoid positive anomaly (approximately 4 mGal) quasi-coincidental with the magnetic anomaly traversing the Pannonian Basin. CHAMP magnetic data (425 km) reveal elongated semicircular negative anomalies for both regions with South-Central Finland having larger amplitude (less than -6 nT) than that over the Pannonian Basin, Hungary (less than -5 nT). In both regions subducted oceanic lithosphere has been proposed as the anomalous body.

  2. Camera, Hand Lens, and Microscope Probe (CHAMP): An Instrument Proposed for the 2009 MSL Rover Mission

    NASA Technical Reports Server (NTRS)

    Mungas, Greg S.; Beegle, Luther W.; Boynton, John E.; Lee, Pascal; Shidemantle, Ritch; Fisher, Ted

    2004-01-01

    The Camera, Hand Lens, and Microscope Probe (CHAMP) will allow examination of martian surface features and materials (terrain, rocks, soils, samples) on spatial scales ranging from kilometers to micrometers, thus enabling both microscopy and context imaging with high operational flexibility. CHAMP is designed to allow the detailed and quantitative investigation of a wide range of geologic features and processes on Mars, leading to a better quantitative understanding of the evolution of the martian surface environment through time. In particular, CHAMP will provide key data that will help understand the local region explored by Mars Surface Laboratory (MSL) as a potential habitat for life. CHAMP will also support other anticipated MSL investigations, in particular by helping identify and select the highest priority targets for sample collection and analysis by the MSL's analytical suite.

  3. Antoine Béchamp: pere de la biologie. Oui ou non?

    PubMed

    Manchester, K L

    2001-06-01

    There is an alternative medicine lobby that, in conjunction with antivivisectionists, believes Louis Pasteur to have been a fraud [R. Bottomley's You Don't Have to Feel Unwell! (Newleaf, 1994) is a recent example]. They frame their accusations around a rivalry between Pasteur and a contemporary, Antoine Béchamp, from whom they suggest Pasteur stole his ideas and then distorted them for his own purposes. This article explores some aspects of the controversies between Béchamp and Pasteur.

  4. Composite hardbody and missile plume (CHAMP 98) IR scene generation program

    NASA Astrophysics Data System (ADS)

    Crow, Dennis R.; Coker, Charles F.

    1998-07-01

    The Composite Hardbody and Missile Plume (CHAMP) program is a computer simulation used to provide time dependent high- fidelity infrared (IR) simulations of airborne vehicles. CHAMP computational algorithms are based on first principle physics that compute hardbody and exhaust plume radiation (absorption, emission, and reflection) for arbitrary vehicle operational state, position, orientation and atmospheric condition. All computations are performed as a function of time to allow complex vehicle dynamics to be simulated. Image processing functions are included to generate anti-aliased focal plane imagery. CHAMP can be utilized to simulate post-boost vehicle, re-entry vehicle, boost missile, theater missile, cruise missile, aircraft, and helicopter applications. CHAMP development is sponsored by the Kinetic Kill Vehicle Hardware- In-the-Loop Simulator (KHILS) facility at Eglin AFB, Florida. CHAMP is routinely utilized by KHILS to support on-going hardware-in-the-loop testing of IR seekers. Many of these tests are complex and diversified. CHAMP has been structured to support these tests by employing current generation object oriented design methodologies that facilitate adaptation to specific test requirements.

  5. Detection and identification of wild yeasts in Champús, a fermented Colombian maize beverage.

    PubMed

    Osorio-Cadavid, Esteban; Chaves-López, Clemencia; Tofalo, Rosanna; Paparella, Antonello; Suzzi, Giovanna

    2008-09-01

    The aim of this study was to identify and characterise the predominant yeasts in Champús, a traditional Colombian cereal-based beverage with a low alcoholic content. Samples of Champús from 20 production sites in the Cauca Valley region were analysed. A total of 235 yeast isolates were identified by conventional microbiological analyses and by polymerase chain reaction-restriction fragment length polymorphism (PCR-RFLP) of ITS1-5.8S rDNA-ITS2. The dominant species were: Saccharomyces cerevisiae, Issatchenkia orientalis, Pichia fermentans, Pichia kluyveri var. kluyveri, Zygosaccharomyces fermentati, Torulospora delbruekii, Galactomyces geotrichum and Hanseniaspora spp. Model Champús systems were inoculated with single strains of some isolated sporogenus species and the aromatic profiles were analysed by SPME. Analysis of data showed that Champús strains produced high amounts of esters. The aromatic compounds produced by Saccharomyces and non-Saccharomyces yeasts from Champús can exert a relevant influence on the sensory characteristics of the fermented beverage. The Champús strains could thus represent an important source for new yeast biotypes with potential industrial applications.

  6. De novo pathogenic variants in CHAMP1 are associated with global developmental delay, intellectual disability, and dysmorphic facial features

    PubMed Central

    Tanaka, Akemi J.; Cho, Megan T.; Retterer, Kyle; Jones, Julie R.; Nowak, Catherine; Douglas, Jessica; Jiang, Yong-Hui; McConkie-Rosell, Allyn; Schaefer, G. Bradley; Kaylor, Julie; Rahman, Omar A.; Telegrafi, Aida; Friedman, Bethany; Douglas, Ganka; Monaghan, Kristin G.; Chung, Wendy K.

    2016-01-01

    We identified five unrelated individuals with significant global developmental delay and intellectual disability (ID), dysmorphic facial features and frequent microcephaly, and de novo predicted loss-of-function variants in chromosome alignment maintaining phosphoprotein 1 (CHAMP1). Our findings are consistent with recently reported de novo mutations in CHAMP1 in five other individuals with similar features. CHAMP1 is a zinc finger protein involved in kinetochore–microtubule attachment and is required for regulating the proper alignment of chromosomes during metaphase in mitosis. Mutations in CHAMP1 may affect cell division and hence brain development and function, resulting in developmental delay and ID. PMID:27148580

  7. The Charge and Mass of Meteoritic Smoke Particles (CHAMPS) Rocket Campaign

    NASA Astrophysics Data System (ADS)

    Knappmiller, S.; Robertson, S. H.; Sternovsky, Z.; Farmer, J.; Dickson, S.

    2010-12-01

    The CHAMPS rocket campaign is a pair of sounding rockets designed to investigate the charge and mass distribution of meteoritic smoke particles (MSPs). It has been suggested that MSPs are a possible condensation nuclei for Noctilucent Clouds (NLC), often called Polar Mesospheric Clouds (PMCs). To date there are no in-situ measurements of the size distribution of MSPs. The charge state of MSPs affects the critical radius at which they become condensation nuclei. Previous rocket campaigns have found positive charge layers, which may be explained by photo-charging of MSPs. The CHAMPS rocket campaign will be launched from the Andoya Rocket Range, Norway in the Fall of 2011. The CHAMPS data is intended to 1) determine whether or not photoemission and photodetachment are mechanisms determining the charge state of MSPs 2) determine the role of MSPs in the overall charge balance of the mesosphere, and 3) determine the mass distribution of the charged fraction of MSPs as a function of altitude. The mass distribution will be directly comparable to recent computational models and remote sensing observations. The data will be taken outside of the NLC season in order to avoid ice particles that would complicate analysis. The data will include measurements of the electron and ion density as well as UV irradiance so that the charging process of MSPs and thus the potential role of MSPs as condensation nuclei can be addressed. The CHAMPS payload is based upon the successful MASS (Mesospheric Aerosol Sampling Spectrometer) payload. The payload includes the MASS instrument, four Colorado Dust Detectors, a pair of Langmuir probes, a pair of positive ion probes, a pair of Faraday rotation antennas, UV detectors, photoemission detectors, and a vacuum Pirani gauge. The MASS instrument returned data on the size distribution of NLC particles in 2007 and will give the size distribution of MSPs during the CHAMPS campaign. Each instrument will be discussed and its relationship to the CHAMPS

  8. Creating Healthy Active Minds for Personal Success (CHAMPS) in Middle School

    ERIC Educational Resources Information Center

    Shawley, Jessica

    2016-01-01

    The purpose of this article is to provide support for middle school physical education programs that meet the developmental needs of students while providing for student choice. With its health and physical education program called Creating Healthy Active Minds for Personal Success (CHAMPS), Moscow Middle School is striving to cultivate student…

  9. De Novo Mutations in CHAMP1 Cause Intellectual Disability with Severe Speech Impairment

    PubMed Central

    Hempel, Maja; Cremer, Kirsten; Ockeloen, Charlotte W.; Lichtenbelt, Klaske D.; Herkert, Johanna C.; Denecke, Jonas; Haack, Tobias B.; Zink, Alexander M.; Becker, Jessica; Wohlleber, Eva; Johannsen, Jessika; Alhaddad, Bader; Pfundt, Rolph; Fuchs, Sigrid; Wieczorek, Dagmar; Strom, Tim M.; van Gassen, Koen L.I.; Kleefstra, Tjitske; Kubisch, Christian; Engels, Hartmut; Lessel, Davor

    2015-01-01

    CHAMP1 encodes a protein with a function in kinetochore-microtubule attachment and in the regulation of chromosome segregation, both of which are known to be important for neurodevelopment. By trio whole-exome sequencing, we have identified de novo deleterious mutations in CHAMP1 in five unrelated individuals affected by intellectual disability with severe speech impairment, motor developmental delay, muscular hypotonia, and similar dysmorphic features including short philtrum and a tented upper and everted lover lip. In addition to two frameshift and one nonsense mutations, we found an identical nonsense mutation, c.1192C>T (p.Arg398∗), in two affected individuals. All mutations, if resulting in a stable protein, are predicted to lead to the loss of the functionally important zinc-finger domains in the C terminus of the protein, which regulate CHAMP1 localization to chromosomes and the mitotic spindle, thereby providing a mechanistic understanding for their pathogenicity. We thus establish deleterious de novo mutations in CHAMP1 as a cause of intellectual disability. PMID:26340335

  10. The adjoint sensitivity method of global electromagnetic induction for CHAMP magnetic data

    NASA Astrophysics Data System (ADS)

    Martinec, Zdeněk; Velímský, Jakub

    2009-12-01

    An existing time-domain spectral-finite element approach for the forward modelling of electromagnetic induction vector data as measured by the CHAMP satellite is, in this paper, supplemented by a new method of computing the sensitivity of the CHAMP electromagnetic induction data to the Earth's mantle electrical conductivity, which we term the adjoint sensitivity method. The forward and adjoint initial boundary-value problems, both solved in the time domain, are identical, except for the specification of prescribed boundary conditions. The respective boundary-value data at the satellite's altitude are the X magnetic component measured by the CHAMP vector magnetometer along the satellite track for the forward method and the difference between the measured and predicted Z magnetic component for the adjoint method. The squares of these differences summed up over all CHAMP tracks determine the misfit. The sensitivities of the CHAMP data, that is the partial derivatives of the misfit with respect to mantle conductivity parameters, are then obtained by the scalar product of the forward and adjoint solutions, multiplied by the gradient of the conductivity and integrated over all CHAMP tracks. Such exactly determined sensitivities are checked against numerical differentiation of the misfit, and good agreement is obtained. The attractiveness of the adjoint method lies in the fact that the adjoint sensitivities are calculated for the price of only an additional forward calculation, regardless of the number of conductivity parameters. However, since the adjoint solution proceeds backwards in time, the forward solution must be stored at each time step, leading to memory requirements that are linear with respect to the number of steps undertaken. Having determined the sensitivities, we apply the conjugate gradient method to infer 1-D and 2-D conductivity structures of the Earth based on the CHAMP residual time series (after the subtraction of static field and secular variations

  11. Coordinating with Humans by Adjustable-Autonomy for Multirobot Pursuit (CHAMP)

    NASA Astrophysics Data System (ADS)

    Dumond, Danielle; Ayers, Jeanine; Schurr, Nathan; Carlin, Alan; Burke, Dustin; Rousseau, Jeffrey

    2012-06-01

    One of the primary challenges facing the modern small-unit tactical team is the ability of the unit to safely and effectively search, explore, clear and hold urbanized terrain that includes buildings, streets, and subterranean dwellings. Buildings provide cover and concealment to an enemy and restrict the movement of forces while diminishing their ability to engage the adversary. The use of robots has significant potential to reduce the risk to tactical teams and dramatically force multiply the small unit's footprint. Despite advances in robotic mobility, sensing capabilities, and human-robot interaction, the use of robots in room clearing operations remains nascent. CHAMP is a software system in development that integrates with a team of robotic platforms to enable them to coordinate with a human operator performing a search and pursuit task. In this way, the human operator can either give control to the robots to search autonomously, or can retain control and direct the robots where needed. CHAMP's autonomy is built upon a combination of adversarial pursuit algorithms and dynamic function allocation strategies that maximize the team's resources. Multi-modal interaction with CHAMP is achieved using novel gesture-recognition based capabilities to reduce the need for heads-down tele-operation. The Champ Coordination Algorithm addresses dynamic and limited team sizes, generates a novel map of the area, and takes into account mission goals, user preferences and team roles. In this paper we show results from preliminary simulated experiments and find that the CHAMP system performs faster than traditional search and pursuit algorithms.

  12. Nanoparticules d'or: De l'imagerie par resonance magnetique a la radiosensibilisation

    NASA Astrophysics Data System (ADS)

    Hebert, Etienne M.

    Cette thèse approfondit l'étude de nanoparticules d'or de 5 nm de diamètre recouvertes de diamideéthanethioldiethylènetriaminepentacétate de gadolinium (DTDTPA:Gd), un agent de contraste pour l'imagerie par résonance magnétique (IRM). En guise de ciblage passif, la taille des nanoparticules a été contrôlée afin d'utiliser le réseau de néovaisseaux poreux et perméable des tumeurs. De plus les tumeurs ont un drainage lymphatique déficient qui permet aux nanoparticules de demeurer plus longtemps dans le milieu interstitiel de la tumeur. Les expériences ont été effectuées sur des souris Balb/c femelles portant des tumeurs MC7-L1. La concentration de nanoparticules a pu être mesurée à l'IRM in vivo. La concentration maximale se retrouvait à la fin de l'infusion de 10 min. La concentration s'élevait à 0.3 mM dans la tumeur et de 0.12 mM dans le muscle environnant. Les nanoparticules étaient éliminées avec une demi-vie de 22 min pour les tumeurs et de 20 min pour le muscle environnant. Les nanoparticules ont été fonctionnalisées avec le peptide Tat afin de leur conférer des propriétés de ciblage actif La rétention de ces nanoparticules a ainsi été augmentée de 1600 %, passant d'une demi-vie d'élimination de 22 min à 350 min. La survie des souris a été mesurée à l'aide de courbes Kaplan-Meier et d'un modèle mathématique évalue l'efficacité de traitements. Le modèle nous permet, à l'aide de la vitesse de croissance des tumeurs et de l'efficacité des traitements, de calculer la courbe de survie des spécimens. Un effet antagoniste a été observé au lieu de l'effet synergétique attendu entre une infusion de Au@DTDTPA:Gd et l'irradiation aux rayons X. L'absence d'effet synergétique a été attribuée à l'épaisseur du recouvrement de DTDTPA:Gd qui fait écran aux électrons produits par l'or. De plus, le moyen d'ancrage du recouvrement utilise des thiols qui peuvent s'avérer être des capteurs de radicaux. De plus

  13. APEX-CHAMP+ high-J CO observations of low-mass young stellar objects. IV. Mechanical and radiative feedback

    NASA Astrophysics Data System (ADS)

    Yıldız, U. A.; Kristensen, L. E.; van Dishoeck, E. F.; Hogerheijde, M. R.; Karska, A.; Belloche, A.; Endo, A.; Frieswijk, W.; Güsten, R.; van Kempen, T. A.; Leurini, S.; Nagy, Z.; Pérez-Beaupuits, J. P.; Risacher, C.; van der Marel, N.; van Weeren, R. J.; Wyrowski, F.

    2015-04-01

    characteristics (density and velocity), whereas CO 3-2 is more sensitive to conditions in the surrounding environment (density). The radiative feedback is responsible for increasing the gas temperature by a factor of two, up to 30-50 K, on scales of a few thousand AU, particularly along the direction of the outflow. The mass of the UV heated gas exceeds the mass contained in the entrained outflow in the inner ~3000 AU and is therefore at least as important on small scales. Appendix A is available in electronic form at http://www.aanda.orgThe CHAMP+ maps (data cubes) are only available at the CDS via anonymous ftp to http://cdsarc.u-strasbg.fr (ftp://130.79.128.5) or via http://cdsarc.u-strasbg.fr/viz-bin/qcat?J/A+A/576/A109

  14. In-flight quality and accuracy of attitude measurements from the CHAMP advanced stellar compass

    NASA Astrophysics Data System (ADS)

    Jørgensen, Peter S.; Jørgensen, John L.; Denver, Troelz; Betto, Maurizio

    2005-01-01

    The German geo-observations satellite CHAMP carries highly accurate vector instruments. The orientation of these relative to the inertial reference frame is obtained using star trackers. These advanced stellar compasses (ASC) are fully autonomous units, which provide, in real time, the absolute attitude with accuracy in the arc second range. In order to investigate the in-flight accuracy of the ASC, the terminology to characterize noise and biases is introduced. Relative instrument accuracy (RIA) and absolute instrument accuracy (AIA) can in principle be determined in-flight. However problems with modeling external noise sources often arise. The special CHAMP configuration with two star tracker cameras mounted fixed together provides an excellent opportunity to determine the AIA in-flight using the inter boresight angle.

  15. Features of highly structured equatorial plasma irregularities deduced from CHAMP observations

    NASA Astrophysics Data System (ADS)

    Xiong, C.; Lühr, H.; Ma, S. Y.; Stolle, C.; Fejer, B. G.

    2012-08-01

    In this study five years of CHAMP (Challenging Mini-satellite Payload) fluxgate magnetometer (FGM) data is used to investigate the characteristics of Equatorial Plasma Bubbles (EPBs). We filtered the FGM data by using band-passes with four different cut-off periods to get the EPBs with different maximum spatial scale sizes in the meridional plane ranging from 76-608 km. Associated with the EPB observations at about 400 km, the typical altitude of CHAMP during the year 2000-2005, we also investigate the post-sunset equatorial vertical plasma drift data from ROCSAT-1 (Republic of China Satellite 1). Since the height of the F-layer is highly correlated with the vertical plasma drift and solar flux, we sorted the ROCSAT-1 data into different groups by F10.7. From the integrated vertical drift we have estimated the post-sunset uplift of the ionosphere. By comparing the properties of EPB occurrence for different scale sizes with the global distribution of plasma vertical uplift, we have found that EPBs reaching higher altitudes are more structured than those which are sampled by CHAMP near the top side of the depleted fluxtube. Such a result is in accord with 3-D model simulations (Aveiro and Hysell, 2010). Small-scale EPB structures are observed by CHAMP when the irregularities reach apex heights of 800 km and more. Such events are encountered primarily in the Brazilian sector during the months around November, when the post-sunset vertical plasma drift is high.

  16. Properties of Traveling Atmospheric Disturbances (TADs) Inferred From CHAMP and GRACE Accelerometer Observations

    NASA Astrophysics Data System (ADS)

    Bruinsma, S. L.; Forbes, J. M.

    2008-12-01

    The accelerometers on the CHAMP and GRACE satellites have made it possible to accumulate near- continuous records of thermosphere density between about 370 and 490 km since May 2001, and July 2002, respectively. They have recorded the response to virtually every significant geomagnetic storm during this period. CHAMP and GRACE are in (near) polar and quasi-circular orbits, sampling 24 hr local time approximately every 4 and 5 months, respectively. These capabilities offer unique opportunities to study the temporal and latitudinal responses of the thermosphere to geomagnetic disturbances. Data from initially 34 geomagnetic storms were explored, but significant and unambiguous TAD activity in the observed response of the thermosphere was detected for about half the events. The atmospheric variability is evaluated by de-trending the data, allowing the extraction of specific ranges in horizontal scale, and analyzing density "residuals". The scale of the perturbation is decisive for its lifetime and relative amplitude. Sometimes the disturbances represent wave-like structures propagating far from the source, and these so- called 'TADs' were detected and described for the May 2003 storm for the first time. Some TADs traveled over the pole into the opposite hemisphere; this was found in both CHAMP and GRACE data. Most TADs propagate equatorward, but poleward propagating TADs have on occasion been detected too. The estimated speeds of the observed TADs are of the order of 400-900 m/s, and their mean scale is approximately 2000 km. The TADs observed with GRACE are significantly slower than those seen in the CHAMP data. The opposite is expected from theory: speed increasing with altitude.

  17. ULF wave activity during the 2003 Halloween superstorm: multipoint observations from CHAMP, Cluster and Geotail missions

    NASA Astrophysics Data System (ADS)

    Balasis, G.; Daglis, I. A.; Zesta, E.; Papadimitriou, C.; Georgiou, M.; Haagmans, R.; Tsinganos, K.

    2012-12-01

    We examine data from a topside ionosphere and two magnetospheric missions (CHAMP, Cluster and Geotail) for signatures of ultra low frequency (ULF) waves during the exceptional 2003 Halloween geospace magnetic storm, when Dst reached ~-380 nT. We use a suite of wavelet-based algorithms, which are a subset of a tool that is being developed for the analysis of multi-instrument multi-satellite and ground-based observations to identify ULF waves and investigate their properties. Starting from the region of topside ionosphere, we first present three clear and strong signatures of Pc3 ULF wave activity (frequency 15-100 mHz) in CHAMP tracks. We then expand these three time intervals for purposes of comparison between CHAMP, Cluster and Geotail Pc3 observations but also to be able to search for Pc4-5 wave signatures (frequency 1-10 mHz) into Cluster and Geotail measurements in order to have a more complete picture of the ULF wave occurrence during the storm. Due to the fast motion through field lines in a low Earth orbit (LEO) we are able to reliably detect Pc3 (but not Pc4-5) waves from CHAMP. This is the first time, to our knowledge, that ULF wave observations from a topside ionosphere mission are compared to ULF wave observations from magnetospheric missions. Our study provides evidence for the occurrence of a number of prominent ULF wave events in the Pc3 and Pc4-5 bands during the storm and offers a platform to study the wave evolution from high altitudes to LEO. The ULF wave analysis methods presented here can be applied to observations from the upcoming Swarm multi-satellite mission of ESA, which is anticipated to enable joint studies with the Cluster mission.

  18. Evaluation of Refractivity Profiles from CHAMP and SAC-C GPS Radio Occultation

    NASA Technical Reports Server (NTRS)

    Poli, Paul; Ao, Chi On; Joiner, Joanna; delaTorreJuarez, Manuel; Hoff, Raymond

    2002-01-01

    The GeoForschungsZentrum's Challenging Minisatellite Payload for Geophysical Research and Application (CHAMP, Germany-US) and the Comision Nacional de Actividades Especiales' Satelite de Aplicaciones Cientificas-C (SAC-C, Argentina-US) missions are the first missions to carry a second-generation Blackjack Global Positioning System (GPS) receiver. One of the new features of this receiver is its ability to sense the lower troposphere closer to the surface than the proof-of-concept GPS Meteorology experiment (GPS/MET). Since their launch, CHAMP and SAC-C have collected thousands of GPS radio occultations, representing a wealth of measurements available for data assimilation and Numerical Weather Prediction (NWP). In order to evaluate the refractivity data derived by the Jet Propulsion Laboratory (JPL) from raw radio occultation measurements, we use Data Assimilation Office (DAO) 6-hour forecasts as an independent state of the atmosphere. We compare CHAMP and SAC-C refractivity (processed by JPL) with refractivity calculated from the DAO global fields of temperature, water vapor content and humidity. We show statistics of the differences as well as histograms of the differences.

  19. Validation of a new plasmapause model derived from CHAMP field-aligned current signatures

    NASA Astrophysics Data System (ADS)

    Heilig, Balázs; Darrouzet, Fabien; Vellante, Massimo; Lichtenberger, János; Lühr, Hermann

    2014-05-01

    Recently a new model for the plasmapause location in the equatorial plane was introduced based on magnetic field observations made by the CHAMP satellite in the topside ionosphere (Heilig and Lühr, 2013). Related signals are medium-scale field-aligned currents (MSFAC) (some 10km scale size). An empirical model for the MSFAC boundary was developed as a function of Kp and MLT. The MSFAC model then was compared to in situ plasmapause observations of IMAGE RPI. By considering this systematic displacement resulting from this comparison and by taking into account the diurnal variation and Kp-dependence of the residuals an empirical model of the plasmapause location that is based on MSFAC measurements from CHAMP was constructed. As a first step toward validation of the new plasmapause model we used in-situ (Van Allen Probes/EMFISIS, Cluster/WHISPER) and ground based (EMMA) plasma density observations. Preliminary results show a good agreement in general between the model and observations. Some observed differences stem from the different definitions of the plasmapause. A more detailed validation of the method can take place as soon as SWARM and VAP data become available. Heilig, B., and H. Lühr (2013) New plasmapause model derived from CHAMP field-aligned current signatures, Ann. Geophys., 31, 529-539, doi:10.5194/angeo-31-529-2013

  20. Quantification du champ electromagnetique et description quantique de la generation du second harmonique a l'interieur d'une microcavite

    NASA Astrophysics Data System (ADS)

    Collette, Marc

    L'existence de particules virtuelles qui surgissent spontanement du vide pour disparaitre tres peu de temps apres leur apparition (les fluctuations du vide) trouve son origine dans le principe d'incertitude de Heisenberg. Par ailleurs, on sait que le phenomene de resonance par confinement explique l'amplification de l'intensite lumineuse a l'interieur d'une cavite ouverte aux frequences de resonances de celle-ci. C'est pourquoi le taux d'apparition des photons virtuels au sein des modes propres d'une cavite est lui aussi amplifie par le resonateur. Mathematiquement, cet effet quantique est decrit par l'existence d'un commutateur " anomal " entre les operateurs d'annihilation et de creation des photons. Nous decrivons les consequences de ce commutateur sur la generation du second harmonique optique (GSH), un processus photonique ou, dans un materiau optiquement non lineaire, deux photons de meme energie fusionnent pour n'en former qu'un seul. On commence ce travail avec un traitement complet et original sur la quantification du champ electromagnetique. On montre ensuite que les fluctuations du vide stimulent le signal de la GSH a l'interieur du milieu confine. Cependant, on constate aussi que les fluctuations du vide jouent le role d'un inhibiteur au declenchement du processus, c'est-a-dire que le seuil de la GSH augmente (il est superieur au seuil minimal de deux photons seulement). En conclusion, les mecanismes intimes de certains processus optiques non lineaires doivent etre reconsideres lorsqu'ils surviennent en presence d'un confinement electromagnetique.

  1. Exploration d'une expérience PV en champ électrique transverse, exploitant la détection par émission stimulée

    NASA Astrophysics Data System (ADS)

    Jahier, E.; Guéna, J.; Lintz, M.; Jacquier, Ph.; Bouchiat, M. A.

    2002-06-01

    Nous présentons ici les premières étapes de la mise en place d'une expérience de violation de parité dans l'atome de césium, dans une nouvelle configuration expérimentale. II s'agit d'une expérience pompe-sonde, exploitant la détection par émission stimulée, où la transition d'excitation est assistée par l'application d'un champ électrique transverse. La possibilité d'appliquer un champ électrique transverse homogène dans une vapeur dense de césium vient de l'emploi de cellules en saphir, dont la conductivité électrique au contact du césium est de plusieurs ordres de grandeur inférieure à celles des cellules en verre.

  2. The development and implementation of theory-driven programs capable of addressing poverty-impacted children's health, mental health, and prevention needs: CHAMP and CHAMP+, evidence-informed, family-based interventions to address HIV risk and care.

    PubMed

    McKernan McKay, Mary; Alicea, Stacey; Elwyn, Laura; McClain, Zachary R B; Parker, Gary; Small, Latoya A; Mellins, Claude Ann

    2014-01-01

    This article describes a program of prevention and intervention research conducted by the CHAMP (Collaborative HIV prevention and Adolescent Mental health Project; McKay & Paikoff, 2007 ) investigative team. CHAMP refers to a set of theory-driven, evidence-informed, collaboratively designed, family-based approaches meant to address the prevention, health, and mental health needs of poverty-impacted African American and Latino urban youth who are either at risk for HIV exposure or perinatally infected and at high risk for reinfection and possible transmission. CHAMP approaches are informed by theoretical frameworks that incorporate an understanding of the critical influences of multilevel contextual factors on youth risk taking and engagement in protective health behaviors. Highly influential theories include the triadic theory of influence, social action theory, and ecological developmental perspectives. CHAMP program delivery strategies were developed via a highly collaborative process drawing upon community-based participatory research methods in order to enhance cultural and contextual sensitivity of program content and format. The development and preliminary outcomes associated with a family-based intervention for a new population, perinatally HIV-infected youth and their adult caregivers, referred to as CHAMP+, is described to illustrate the integration of theory, existing evidence, and intensive input from consumers and healthcare providers. PMID:24787707

  3. De Novo Truncating Mutations in the Kinetochore-Microtubules Attachment Gene CHAMP1 Cause Syndromic Intellectual Disability.

    PubMed

    Isidor, Bertrand; Küry, Sébastien; Rosenfeld, Jill A; Besnard, Thomas; Schmitt, Sébastien; Joss, Shelagh; Davies, Sally J; Lebel, Robert Roger; Henderson, Alex; Schaaf, Christian P; Streff, Haley E; Yang, Yaping; Jain, Vani; Chida, Nodoka; Latypova, Xenia; Le Caignec, Cédric; Cogné, Benjamin; Mercier, Sandra; Vincent, Marie; Colin, Estelle; Bonneau, Dominique; Denommé, Anne-Sophie; Parent, Philippe; Gilbert-Dussardier, Brigitte; Odent, Sylvie; Toutain, Annick; Piton, Amélie; Dina, Christian; Donnart, Audrey; Lindenbaum, Pierre; Charpentier, Eric; Redon, Richard; Iemura, Kenji; Ikeda, Masanori; Tanaka, Kozo; Bézieau, Stéphane

    2016-04-01

    A rare syndromic form of intellectual disability with impaired speech was recently found associated with mutations in CHAMP1 (chromosome alignment-maintaining phosphoprotein 1), the protein product of which is directly involved in microtubule-kinetochore attachment. Through whole-exome sequencing in six unrelated nonconsanguineous families having a sporadic case of intellectual disability, we identified six novel de novo truncating mutations in CHAMP1: c.1880C>G p.(Ser627*), c.1489C>T; p.(Arg497*), c.1876_1877delAG; p.(Ser626Leufs*4), c.1043G>A; p.(Trp348*), c.1002G>A; p.(Trp334*), and c.958_959delCC; p.(Pro320*). Our clinical observations confirm the phenotypic homogeneity of the syndrome, which represents therefore a distinct clinical entity. Besides, our functional studies show that CHAMP1 protein variants are delocalized from chromatin and are unable to bind to two of its direct partners, POGZ and HP1. These data suggest a pathogenic mechanism of the CHAMP1-associated intellectual disability syndrome mediated by direct interacting partners of CHAMP1, several of which are involved in chromo/kinetochore-related disorders. PMID:26751395

  4. Simultaneous Observations of TADs in GOCE, CHAMP and GRACE Density Data Compared with CTIPe

    NASA Astrophysics Data System (ADS)

    Bruinsma, S. L.; Fedrizzi, M.

    2012-12-01

    The accelerometers on the CHAMP and GRACE satellites have made it possible to accumulate near-continuous records of thermosphere density between about 300 and 490 km since May 2001, and July 2002, respectively. Since November 2009, a third gravity field satellite mission, ESA's GOCE, is in a very low and near heliosynchronous dawn-dusk orbit at about 270 km. The spacecraft is actively maintained at that constant altitude using an ion propulsion engine that compensates the aerodynamic drag in the flight direction. The thrust level, combined with accelerometer and satellite attitude data, is used to compute atmospheric densities and cross-track winds. The response of the thermosphere to geomagnetic disturbances, i.e., space weather, has been extensively studied using the exceptional datasets of CHAMP and GRACE. Thanks to GOCE we now have a third excellent data set for these studies. In this presentation we will show the observed density and its variability for the geomagnetic storm of 5 April 2010, and compare it with predictions along the orbits obtained from a self-consistent physics-based coupled model of the thermosphere, ionosphere, plasmasphere and electrodynamics (CTIPe). For this storm, the CHAMP and GOCE orbit planes were perpendicular (12/24 Local Solar Time, and 6/18 LST, respectively) and the altitude difference was only approximately 30 km. The GRACE densities are at a much higher altitude of about 475 km. Wave-like features are revealed or enhanced after filtering of the densities and calculation of relative density variations. Traveling Atmospheric Disturbances are observed in the data, and the model's fidelity in reproducing the waves is evaluated.

  5. Spatial frequencies associated with the latitudinal structures of ionospheric currents seen by CHAMP satellite

    NASA Astrophysics Data System (ADS)

    Thomas, Neethal; Vichare, Geeta; Sinha, A. K.

    2016-07-01

    The CHAMP magnetic field variations during international quiet days of low solar activity period 2008-2009 are investigated. The present paper reports the existence of frequency peaks ≤20 mHz in the compressional component of the magnetic field in almost all CHAMP passes. The magnetic field variations associated with these frequencies have amplitude of a few tens of nT during the daytime. The geomagnetic activity and interplanetary magnetic field parameters were observed to be low during the period of study. The spectral powers of the observed frequencies show no dependence on solar wind velocity and cone angle; hence, the reported frequencies are not related to the geomagnetic pulsations. For frequency-peaks ≤15 mHz, strong local time dependence is observed with maximum power near noon and minimum at night. The longitudinal and seasonal variation of the powers of these frequency peaks match well with those of the equator-to-middle latitude ionospheric currents derived by the earlier studies. As a polar Low Earth Orbiting (LEO) satellite spans the entire range of latitudes within few minutes, it monitors the geomagnetic field variations caused by the quiet-time ionospheric currents flowing at different latitudes. This can result in certain frequencies in the magnetic field recorded by LEO satellites. We demonstrate that the frequencies <10 mHz are mainly due to the latitudinal structure of the equatorial electrojet. The observed frequencies in CHAMP data are therefore attributed to the latitudinal structures of the ionospheric currents that are monitored only by the polar LEO satellites and are found to alter the observations of geomagnetic pulsations (Pc4-5 and Pi2) significantly.

  6. Electron density profiles obtained from CHAMP GPS radio occultation measurements: Initial results from GFZ

    NASA Astrophysics Data System (ADS)

    Arras, Christina; Schmidt, Torsten; Lee, Woo-Kyoung; Wickert, Jens; Heise, Stefan; Beyerle, Georg; Rothacher, Markus; Jakowski, Norbert

    GPS radio occultation signals received by Low Earth Orbit satellites provide global information about vertical distribution of lower atmospheric parameters (e.g., temperature and water vapour) and electron density in the ionosphere. Since its launch in July 2000 the German geoscience satellite CHAMP has collected about 400,000 occultation measurements. These data form a first and unique long-term dataset of ionospheric profiles, but also of other geophysical variables as temperature, pressure and water vapour in the lower atmosphere. We present initial results of the ionospheric occultation data analyses at GFZ. Vertical electron density profiles from CHAMP are derived using a recently developed software package. To obtain electron densities from calibrated TEC (Total Electron Content) data the so-called onion peeling method is used. The application of this technique allows for the derivation of the electron density profile iteratively starting from the top altitude. The derived profiles are compared with corresponding data processed by UCAR (University Corporation of Atmospheric Research) and DLR Neustrelitz, but also with independent PLP (Planar Langmuir Probe) measurements from CHAMP. These investigations are complemented by case studies comparing the profiles with ground based ionosonde measurements. The high vertical resolution of the derived ionospheric profiles reveals thin vertical ionospheric structures such as sporadic E layers. We investigate the occurrence distribution of these layers in more detail. Sporadic E appears predominantly during summer in the lower ionosphere and has a considerable effect on the propagation of the GPS radio occultation signals. This feature is used to derive information on the altitude and on the intensity of these irregularities.

  7. A Census of Accretion Power in the Universe with the Chandra Multiwavelength Project (ChaMP)

    NASA Astrophysics Data System (ADS)

    Hooper, E. J.; ChaMP Collaboration

    2002-05-01

    A vexing problem in AGN research is that their complex taxonomy & wide range of properties make it difficult to compile a broadly representative sample, particularly one containing obscured sources. The relatively recent results indicating that supermassive black holes may be entrenched in every galaxy bulge give added impetus to conducting a census of accretion power in the universe which is as comprehensive as possible. Two new X-ray telescopes, Chandra & XMM, have increased X-ray survey capability by orders of magnitude, bringing X-ray selection to the fore as one of the preeminent methods for compiling deep, widely representative samples of AGN. A large serendipitous survey with Chandra is underway, the Chandra Multiwavelength Project (ChaMP; PI, B. Wilkes). The ChaMP reaches far deeper than previous wide-area surveys while covering much greater area than Chandra PI deep surveys. Chandra's combination of depth, hard X-ray sensitivity, positional accuracy, & large number of serendipitous sources makes ChaMP unique, and it will remain so for the foreseeable future. Much of the scientific return of an X-ray AGN survey requires redshifts & source characterizations provided by spectroscopy, either of the active nucleus or, if it is too obscured, the host galaxy. A program is underway, under the aegis of the NSF Astronomy & Astrophysics Postdoctoral Fellowship Program, to obtain low-resolution spectra of hundreds of ChaMP sources with the 2.7 m telescope and the 9 m Hobby-Eberly Telescope (HET) at McDonald Observatory. The NSF Fellowship also includes an education component. The author is working with an innovative new program at UT Austin for training science teachers, called UTeach, which addresses many problems in teacher recruitment, education, retention, and support. UTeach is a joint effort of the Colleges of Natural Science & Education, and the Austin school district. It trains future teachers well in math and science, gives them early and continuing field

  8. VizieR Online Data Catalog: YSOs APEX-CHAMP+ high-J CO maps (Yildiz+,

    NASA Astrophysics Data System (ADS)

    Yildiz, U. A.; Kristensen, L. E.; van Dishoeck, E. F.; Hogerheijde, M. R.; Karska, A.; Belloche, A.; Endo, A.; Frieswijk, W.; Gusten, R.; van Kempen, T. A.; Leurini, S.; Nagy, Z.; Perez-Beaupuits, J. P.; Risacher, C.; van der Marel, N.; van Weeren, R. J.; Wyrowski, F.

    2015-01-01

    Files contain the observations of 12CO and 13 JCMT-HARP-B and 12CO and 13CO 6-5 from APEX-CHAMP+, toward 26 low mass protostars as listed below. The data analysis was done via GILDAS-CLASS, where raw data are processed to obtain regularly sampled data. The spectra are given in two formats; fits cube and GILDAS lmv cube. File names are self explanatory, i.e., SOURCENAMEMOLECULETRANSITIONTELESCOPENAMEcube_VELOCITYRESOLUTION.fits and SOURCENAMEMOLECULETRANSITIONTELESCOPENAMEcube_VELOCITYRESOLUTION.lmv (3 data files).

  9. Spaceborne accelerometry and temporal gravity analysis from the CHAMP satellite mission

    NASA Astrophysics Data System (ADS)

    Thompson, Blair F.

    2005-11-01

    The research presented in this thesis was conducted with two central objectives: (1) the development of techniques for the incorporation of satellite accelerometry in geodetic applications, and (2) the recovery of short-period temporal variations in Earth's gravity field from the tracking data of a single, low-orbiting satellite. The data used in this research consisted of double-differenced GPS carrier phase data (approximately 65,000 observations per 30-hour arc), and satellite laser ranging (SLR) data (approximately 100 observations per 30-hour arc) from the CHAMP satellite for the year 2002. The average 30-hour GPS residual RMS of reduced-dynamic orbit determination was 0.80 cm. The average residual RMS of the SLR data was 3.96 cm. The ephemeris (trajectory) estimated from reduced-dynamic processing served as pseudo-observation data for accelerometer calibration and temporal gravity recovery, eliminating the thousands of nuisance parameters associated with the GPS data. Low-rate (0.1 Hz) accelerometer data were calibrated using conventional non-conservative force models, then integrated into the equations of motion in lieu of all non-conservative forces. Attitude quaternions based on in situ star camera data were used to model spacecraft attitude. Thruster perturbations were constrained together by thruster pair and modeled as impulsive velocity increments. The annual signals of the gravity field up to degree and order three (3 x 3) were recovered, at least partially, from the CHAMP tracking data. Estimating temporal coefficients higher than degree three resulted in strong correlation between coefficients. Analysis of the resulting CHAMP annual gravity signals showed a favorable comparison with the existing results of SLR data gathered over multiple years (1979--2004) from multiple satellites in various orbits. The CHAMP results also compared favorably with the preliminary results of the Gravity Recovery and Climate Experiment (GRACE) satellite mission, and

  10. Champs morphogenetiques mis en evidence par l'etude au microscope electronique a balayage des soies au niveau des pattes d'abeilles (apoidea, megachilidae).

    PubMed

    Pasteels, J M; Pasteels, J J

    1973-01-01

    The hairs covering the legs of several species of female megachilid bees are arranged in imbricated fields. At the boundaries of these fields, either the hairs show a morphology intermediate between those of the contiguous fields, or there is a narrow strip with an irregular mosaïc of several hair types. It is suggested that: 1. The structure of the hairs may be determined by the territory in which the trichogenous cell is located. 2. Some morphogenetic fields are bidimensional and cross the segmentary boundaries. The name 'regional fields' is proposed for them. 3. The regional fields may be modulated within each segment into which they extend.

  11. GPS Radio Occultation With Champ: The First Year of The Experiment

    NASA Astrophysics Data System (ADS)

    Wickert, J.; Beyerle, G.; Marquardt, C.; Schmidt, T.; Reigber, Ch.; König, R.; Grunwaldt, L.

    The GPS radio occultation experiment onboard the German CHAMP (CHAllenging Minisatellite Payload) satellite was started on February 11, 2001. During an one hour measurement period seven occultation events were recorded. Already these first mea- surements indicated that in spite of the activated anti-spoofing (A/S) mode of the GPS the state-of-the-art GPS flight receiver combined with favorable antenna characteris- tics allows for global atmosphere sounding with high accuracy and vertical resolution. More than 50,000 occultations are expected as of April 2002. The first year of the CHAMP occultation experiment is reviewed. The occultation infrastructure at the Ge- oForschungsZentrum (GFZ) Potsdam and the operational occultation data processing is characterized. An overview of GFZSs operational data processing, the scientific data analysis and the results of the first year occultation experiment is given. The quality of CHAMPSs occultation data products (vertical atmospheric profiles) is evaluated. Re- sults of data analysis using wave optic methods are presented, e.g. contributions from signals, reflected from EarthSs surface, were found in the occultation data in about 20-30% of the measurements using a radio holographic analysis. Furthermore, the termination of the Selective Availability (SA) mode of the GPS made the application of less-than-double-differencing techniques for GPS occultation analysis feasible. Re- sults of occultation data processing using a space-based single differencing technique are compared with those generated by double differencing as a reference.

  12. Globally averaged exospheric temperatures derived from CHAMP and GRACE accelerometer measurements

    NASA Astrophysics Data System (ADS)

    Wise, J. O.; Burke, W. J.; Sutton, E. K.

    2012-04-01

    Neutral densities (ρ) inferred from accelerometer measurements on the polar-orbiting Challenging Minisatellite Payload (CHAMP) and Gravity Recovery and Climate Experiment (GRACE) satellites are used to compile exospheric temperatures (T∞) during extended periods in 2003 and 2004 when their orbital planes were nearly parallel and at quadrature, respectively. Exospheric temperatures were first estimated using ρ-h-T∞ relationships implicit within the Jacchia models, then averaged over individual orbits. We found good agreement between the orbital-averaged T∞ obtained from CHAMP and GRACE accelerometer data as well as with globally averaged exospheric temperatures derived from drag measurements from the constellation of satellites used in the High-Accuracy Satellite Drag Model. Our analysis corrects a critical conjecture by Burke (2008) that globally averaged T∞ is essentially the same as orbit-averaged values obtained by polar-orbiting satellites, independent of the local time of their orbital planes. Unlike the symmetric 0200-1400 LT distribution of T∞ minima and maxima found in early Jacchia models, presented data indicate that the minima are located closer to the dawn meridian. We also demonstrate that the averaging technique used to estimate T∞ affects the outcomes. Statistical analyses provide an empirical basis for improving estimates of the thermosphere's total energy budget.

  13. Properties of Traveling Atmospheric Disturbances (TADs) inferred from CHAMP accelerometer observations

    NASA Astrophysics Data System (ADS)

    Bruinsma, Sean

    The STAR accelerometer on the CHAMP satellite has made it possible to accumulate nearcontinuous simultaneous records of thermosphere density between about 370 and 470 km since May, 2001. It has recorded the response to virtually every significant geomagnetic storm during this period. CHAMP is in a near-polar and quasi-circular orbit, sampling 24 hr local time approximately every 4 months. These capabilities offer unique opportunities to study the temporal and latitudinal responses of the thermosphere to geomagnetic disturbances. Data from initially 33 geomagnetic storms were explored, but significant and unambiguous TAD activity in the observed response of the thermosphere was detected for only 12 events. The atmospheric variability is evaluated by de-trending the data and analyzing density "residuals" corresponding to several ranges of horizontal scale. The scale of the perturbation is decisive for its lifetime and relative amplitude. Sometimes the disturbances represent wave-like structures, and these TADs were detected and described for the May 2003 storm for the first time. Some TADs traveled over the pole into the opposite hemisphere, which was never observed so far. Most TADs propagate equatorward, but poleward propagating TADs have on occasion been detected too. The estimated speeds of the observed TADs are of the order of 400-900 m/s, and their mean scale is approximately 2000 km.

  14. Mysterious misalignments between geomagnetic and stellar reference frames seen in CHAMP and Swarm satellite measurements

    NASA Astrophysics Data System (ADS)

    Maus, Stefan

    2015-12-01

    The orientation of a spacecraft in Low Earth Orbit can be determined accurately from either magnetic field measurements or star camera images. Ideally, the independently computed spacecraft attitudes should agree. However, we find that the German CHAMP and European Space Agency triple-satellite Swarm geomagnetic satellites exhibit consistent misalignments between the stellar and geomagnetic reference frames, which oscillate with the local time of the orbit. Having an amplitude of 20 arcsec, these oscillations are more than an order of magnitude larger than the stability of the optical bench, which cohosts the magnetometers and star cameras. The misalignments could originate either from the magnetometer or star camera measurements. On one hand, as-yet-unknown external magnetic field contributions could appear as a rotation of the geomagnetic reference frame. On the other hand, the observed misalignments agree in amplitude and phase with the effects of stellar aberration, caused by the movement of the star cameras relative to the light rays emitted by the stars. This is surprising because stellar aberration is allegedly already corrected for by the star image processing system. Resolving these mysterious misalignments is key to fulfilling the measurement accuracy requirements and science objectives of the ongoing Swarm mission. If caused by stellar aberration, fully correcting for this effect could significantly improve the attitude accuracy not only of CHAMP and Swarm, but also of several other past and ongoing scientific satellite missions.

  15. Daily variation of diurnal thermal tides from CHAMP and GOCE accelerometer measurements

    NASA Astrophysics Data System (ADS)

    Gasperini, Federico; Doornbos, Eelco; Forbes, Jeffrey M.; Bruinsma, Sean; Haeusler, Kathrin; Hagan, Maura

    Daily migrating and non-migrating diurnal tides in exospheric temperature derived from simultaneous accelerometer measurements on CHAMP (near 300 km) and GOCE (near 260 km) are studied for the intervals November-December 2009 and March-April 2010. Neutral densities are converted to exospheric temperatures using the NRLMSISe00 empirical model and by iterating on a convenient parameter (e.g. F10.7 solar flux). This methodology is validated using NCAR TIME-GCM simulations for this period as a mock data set, and results are compared to an approach where differences between ascending and descending orbital measurements are used to estimate diurnal tides for CHAMP and GOCE separately. The tidal components analyzed are the westward-propagating components with zonal wave numbers s=1 and s=2 (DW1 and DW2) and the eastward-propagating components with s=-2 and s=-3 (DE2 and DE3). Spectral analyses are used to reveal potential planetary wave modulations of the daily tidal amplitudes.

  16. A Comparison of Equatorial Plasma Bubble Observations by DMSP, ROCSAT, and CHAMP

    NASA Astrophysics Data System (ADS)

    Kachner, K.; Burke, W. J.; Cooke, D.; Gentile, L. C.; Roth, C.; Su, S. Y.

    2004-05-01

    We compare evening sector plasma density measurements from polar-orbiting satellites of the Defense Meteorological Satellite Program (DMSP) and the Challenging Minisatellite Payload (CHAMP) Program with observations from the Republic of China Satellite (ROCSAT) in a low-inclination orbit. Our study focused on several days during March of 2002 when multiple satellite conjunctions enabled comparison of equatorial plasma bubble (EPB) observations in the evening sector at ~400 (CHAMP), ~600 (ROCSAT), and 840 (DMSP) km altitudes. Radar measurements taken during an Atmosphere Explorer E overflight of Kwajalein show that EPBs have elongated, wedge-like cross sections that extend from their bottomside sources into the topside ionosphere [Tsunoda et al., 1982]. Objectives of this study are to validate the Tsunoda model of EPB development and to establish criteria for distinguishing between EPB encounters and times when the peak of the F layer rose above 400 km. Multipoint observations at various altitudes also provide critical insights on EPB formation, magnitude, and duration that will be useful for mission planning and the analysis of data acquired by the Communication/Navigation Outage Forecasting System (C/NOFS) satellite. Reference: Tsunoda, R. T., et al., JGR, 87, 9171,1982.

  17. The Near Real Time Data Processing System For GPS Radio Occultation Data From Champ At Gfz Potsdam

    NASA Astrophysics Data System (ADS)

    Schmidt, T.; Wickert, J.; Marquardt, Ch.; Beyerle, G.; Reigber, Ch.; Wehrenpfennig, A.

    GPS radio occultation measurements onboard low earth orbiting satellites (CHAMP) offer a prominent method for global and continuous monitoring of the Earth's atmo- sphere. Data assimilation studies using radio occultation data have already shown that this new type of remote sensing technique improves the accuracy of global and re- gional weather analyses and predictions. The use of products obtained from radio occultation data as, e.g., refractivity, tem- perature, or humidity profiles, by weather service centers requires an operational data processing system generating and delivering data products automatically within a 3 hour time limit. Since one year such a near real time data processing system is oper- ated at GFZ Potsdam with radio occultation data from the German satellite CHAMP (Challenging Minisatellite Payload). This system, the CHAMP Atmospheric Processor (CAP), will be introduced. The con- trolling and scientific components including ground infrastructure, data flow and soft- ware modules are discussed. CAP is designed to be easily extendable by additional scientific modules or input data. Thus, it also allows for an extension to other single- or multi-satellite occultation missions as, e.g., GRACE to be launched in March 2002. By end of April 2002 more than 50.000 occultations will be recorded. Extensive statis- tics as daily and monthly averages of processed occultations and global distributions of occultation events from one year of CHAMP radio occultation data will be presented.

  18. Taking Their Show on the Road: Becky Hebert & Siobhan Champ-Blackwell--National Network of Libraries of Medicine

    ERIC Educational Resources Information Center

    Library Journal, 2005

    2005-01-01

    They're two very different women with the same mission: outreach to medically underserved populations. Both work for the National Network of Libraries of Medicine. Becky Hebert (left) covers the Southeast/Atlantic region, and Siobhan Champ-Blackwell, the mid-continental region. They spend much of their lives on the road, exhibiting at minority…

  19. Global gravity field models from the GPS positions of CHAMP, GRACE and GOCE satellites

    NASA Astrophysics Data System (ADS)

    Bezděk, A.; Sebera, J.; Klokočník, J.; Kostelecký, J.

    2012-04-01

    The aim of our work is to generate Earth's gravity field models from the GPS positions of low Earth orbiters. We will present our inversion method and numerical results based on the real-world data of CHAMP, GRACE and GOCE satellites. The presented inversion method is based on Newton's second law of motion, which relates the observed acceleration of the satellite with the forces acting on it. The vector of the observed acceleration is obtained through a numerical second-derivative filter applied to the time series of the kinematic positions. Forces other than those due to the geopotential are either modelled (lunisolar perturbations, tides) or provided by the onboard measurements (nongravitational perturbations). Then the observation equations are formulated using the gradient of the spherical harmonic expansion of the geopotential. From this linear system the harmonic coefficients are directly obtained. We do not use any a priori gravity field model. Although the basic scheme of the acceleration approach is straightforward, the implementation details play a crucial role in obtaining reasonable results. The numerical derivative of noisy data (here the GPS positions) strongly amplifies the high frequency noise and creates autocorrelation in the observation errors. We successfully solve both of these problems by using the generalized least squares method, which defines a linear transformation of the observation equations. In the transformed variables the errors become uncorrelated, so the ordinary least squares estimation may be used to find the regression parameters with correct estimates of their uncertainties. The digital filter of the second derivative is an approximation to the analytical operation. We will show how different the results might be depending on the particular choice of the parameters defining the filter. Another problem is the correlation of the errors in the GPS positions. Here we use the tools from time series analysis. The systematic behaviour

  20. Observations of ionospheric gravity and diamagnetic current systems inferred from CHAMP and Swarm measurements

    NASA Astrophysics Data System (ADS)

    Alken, P.

    2015-12-01

    Large scale currents in the ionosphere are driven by a variety of sources, including neutral winds, gravity, and plasma pressure gradients. While thestronger day-time wind-driven currents have been extensively studied, gravity and diamagnetic currents in the ionosphere have receivedlittle attention, but can have substantial effects even during the night. With the availability of a new generation of magnetic field models basedon high-accuracy satellite magnetic measurements, it becomes increasingly important to account for these smaller current systems. In this study,we use over a decade of high-quality geomagnetic field measurements from the CHAMP and Swarm missions to study the seasonal and longitudinalstructure of these currents. These results allow us to visualize the global structure of these currents and quantify their magneticperturbations both on the ground and at satellite altitude.

  1. Synthetic thermosphere winds based on CHAMP neutral and plasma density measurements

    NASA Astrophysics Data System (ADS)

    Gasperini, F.; Forbes, J. M.; Doornbos, E. N.; Bruinsma, S. L.

    2016-04-01

    Meridional winds in the thermosphere are key to understanding latitudinal coupling and thermosphere-ionosphere coupling, and yet global measurements of this wind component are scarce. In this work, neutral and electron densities measured by the Challenging Minisatellite Payload (CHAMP) satellite at solar low and geomagnetically quiet conditions are converted to pressure gradient and ion drag forces, which are then used to solve the horizontal momentum equation to estimate low latitude to midlatitude zonal and meridional "synthetic" winds. We validate the method by showing that neutral and electron densities output from National Center for Atmospheric Research (NCAR) Thermosphere Ionosphere Mesosphere Electrodynamics-General Circulation Model (TIME-GCM) can be used to derive solutions to the momentum equations that replicate reasonably well (over 85% of the variance) the winds self-consistently calculated within the TIME-GCM. CHAMP cross-track winds are found to share over 65% of the variance with the synthetic zonal winds, providing further reassurance that this wind product should provide credible results. Comparisons with the Horizontal Wind Model 14 (HWM14) show that the empirical model largely underestimates wind speeds and does not reproduce much of the observed variability. Additionally, in this work we reveal the longitude, latitude, local time, and seasonal variability in the winds; show evidence of ionosphere-thermosphere (IT) coupling, with enhanced postsunset eastward winds due to depleted ion drag; demonstrate superrotation speeds of ˜27 m/s at the equator; discuss vertical wave coupling due the diurnal eastward propagating tide with zonal wave number 3 and the semidiurnal eastward propagating tide with zonal wave number 2.

  2. Characteristics of F-region dynamo currents deduced from CHAMP magnetic field measurements

    NASA Astrophysics Data System (ADS)

    Park, Jaeheung; Lühr, Hermann; Min, Kyoung Wook

    2010-10-01

    Using magnetic field observations of the CHAMP satellite we provide the first comprehensive study of F-region dynamo currents as a function of season, local time, geographic longitude, and solar activity. From bipolar variations of the zonal magnetic field component the density of vertical current driven by the F-region dynamo is deduced. The current strength is smallest around June solstice, which is attributed to a reduced F-region Pedersen conductance caused by a lower electron density and neutral density at that season. During the hours around noon highest current densities are observed. They are flowing downward over the dip equator. A secondary peak of upward currents appears at dusk. The polarity switch occurs between15 and 16 (local time) independent of season. The noontime F-region dynamo current peaks at longitudes connected to the South Atlantic Anomaly, which can be explained by the enhanced conductivity in the region of reduced B field. The F-region current at dusk exhibits no peak in the longitude sector of the South Atlantic Anomaly. At noon, the F-region dynamo currents exhibit a wave 4 longitudinal structure during equinoxes and June solstice. The wave 4 signature becomes weak during December solstice. At dusk the wave 4 signature of F-region dynamo currents is much reduced in all seasons. This behavior can be explained by the DE3 tidal signature in the zonal wind at CHAMP altitude. F-region dynamo currents increase linearly with the solar flux index, F10.7, during both noon and dusk time sectors. The increase in current strength with increasing F10.7 is slightly higher at dusk than at noon.

  3. Collective flow in Au + Au collisions

    SciTech Connect

    Ritter, H.G.; EOS Collaboration

    1994-05-01

    Based on a preliminary sample of Au + Au collisions in the EOS time projection chamber at the Bevalac, we study sideward flow as a function of bombarding energy between 0.25A GeV and 1.2A GeV. We focus on the increase in in-plane transverse momentum per nucleon with fragment mass. We also find event shapes to be close to spherical in the most central collisions, independent of bombarding energy and fragment mass up to {sup 4}He.

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

    NASA Astrophysics Data System (ADS)

    Fournier, Patrick

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

  5. Analysis of the IMAGE RPI electron density data and CHAMP plasmasphere electron density reconstructions with focus on plasmasphere modelling

    NASA Astrophysics Data System (ADS)

    Gerzen, T.; Feltens, J.; Jakowski, N.; Galkin, I.; Reinisch, B.; Zandbergen, R.

    2016-09-01

    The electron density of the topside ionosphere and the plasmasphere contributes essentially to the overall Total Electron Content (TEC) budget affecting Global Navigation Satellite Systems (GNSS) signals. The plasmasphere can cause half or even more of the GNSS range error budget due to ionospheric propagation errors. This paper presents a comparative study of different plasmasphere and topside ionosphere data aiming at establishing an appropriate database for plasmasphere modelling. We analyze electron density profiles along the geomagnetic field lines derived from the Imager for Magnetopause-to-Aurora Global Exploration (IMAGE) satellite/Radio Plasma Imager (RPI) records of remote plasma sounding with radio waves. We compare these RPI profiles with 2D reconstructions of the topside ionosphere and plasmasphere electron density derived from GNSS based TEC measurements onboard the Challenging Minisatellite Payload (CHAMP) satellite. Most of the coincidences between IMAGE profiles and CHAMP reconstructions are detected in the region with L-shell between 2 and 5. In general the CHAMP reconstructed electron densities are below the IMAGE profile densities, with median of the CHAMP minus IMAGE residuals around -588 cm-3. Additionally, a comparison is made with electron densities derived from passive radio wave RPI measurements onboard the IMAGE satellite. Over the available 2001-2005 period of IMAGE measurements, the considered combined data from the active and passive RPI operations cover the region within a latitude range of ±60°N, all longitudes, and an L-shell ranging from 1.2 to 15. In the coincidence regions (mainly 2 ⩽ L ⩽ 4), we check the agreement between available active and passive RPI data. The comparison shows that the measurements are well correlated, with a median residual of ∼52 cm-3. The RMS and STD values of the relative residuals are around 22% and 21% respectively. In summary, the results encourage the application of IMAGE RPI data for

  6. Le champ critique de claquage de films d'oxyde de polyphénylène réalisés par voie électrochimique

    NASA Astrophysics Data System (ADS)

    Adohi, B.; Gosse, J. P.; Gosse, B.

    1991-10-01

    The electrical breakdown of thin films of polyphenylene oxide electrochemically deposited on stainless steel plane substrates has been studied. First it was examined the dependence of the medium surrounding the dielectric and the electrodes (nature, hydrostatic pressure) on the breakdown voltage and on its statistical distribution. Between sphere and plane electrodes, it appears that even for pressurified gases, breakdown of the film is caused by the gas breakdown. We have analysed the discharges occurring at atmosphere pressure in the test cell. Breakdown of the film occurred when the electric field due to the charge deposited on its surface was about 230 V/μm. We have also studied self-healing capacitors with PPO as a dielectric, and determined the life-time of this material. On a étudié le claquage électrique de films minces d'oxyde de polyphénylène de quelques microns d'épaisseur déposés par voie électrochimique sur un plan en acier inoxydable. L'étude a d'abord été faite en rampe de tension continue dans la géométrie d'électrodes sphèreplan, en fonction du milieu ambiant liquide ou gazeux. L'influence de la pression sur la rigidité diélectrique du matériau, les distributions statistiques de Weibull et les cratères formés au moment du claquage, dans les différents milieux et dans les deux polarités de l'électrode sphérique montrent que le claquage du matériau est causé par des décharges qui se produisent dans le milieu environnant. A partir de l'analyse quantitative de ces décharges, on propose comme critère de caractérisation de la rupture d'un matériau sounmis aux décharges, le champ créé au moment de la rupture par les charges déposées à sa surface. On a réalisé ensuite des échantillons plans << autocicatrisables >> par dépôt de couches minces d'aluminium (quelques milliers d'Å d'épaisseur) sur le film de PPO. On étudie dans cette configuration la durée de vie du matériau.

  7. Effects of solar disturbances on the thermosphere densities and winds from CHAMP and GRACE satellite accelerometer data

    NASA Astrophysics Data System (ADS)

    Sutton, Eric K.

    2008-10-01

    This dissertation focuses on using a new satellite data source to characterize the response of the thermosphere to several different types of dynamical forcing. In this study, the methods used to calculate a continuous database of atmospheric parameters are developed and validated. In particular, the instruments available on the CHAllenging Mini-satellite Payload (CHAMP) mission are used to deduce in-situ atmospheric density and a component of wind velocity in the thermosphere. The global coverage and thorough sampling of local time, afforded by the carefully chosen orbital parameters of the satellite mission, ensure the value of this dataset. In addition, the unprecedented spatial and temporal resolution provided by the CHAMP satellite enables the in-depth analyses of several response characteristics of the neutral atmosphere which have rarely, and in some cases never, been observed directly. Over large time scales, Solar Extreme Ultraviolet (EUV) radiation provides the majority of energy that heats the thermosphere, while Joule heating associated with high-latitude geomagnetic disturbances is a sporadic, yet often more intense source. Both of these sources are capable of providing short bursts of energy which can excite different modes of response, including atmospheric gravity waves and enhanced global circulation. These features are observed in CHAMP data and compared with numerical simulations from the Thermosphere-Ionosphere-Electrodynamics General Circulation Model (TIEGCM) developed by the National Center for Atmospheric Research (NCAR), which embodies our current level of understanding of the upper atmosphere.

  8. Development and Optical Testing of the Camera, Hand Lens, and Microscope Probe with Scannable Laser Spectroscopy (CHAMP-SLS)

    NASA Technical Reports Server (NTRS)

    Mungas, Greg S.; Gursel, Yekta; Sepulveda, Cesar A.; Anderson, Mark; La Baw, Clayton; Johnson, Kenneth R.; Deans, Matthew; Beegle, Luther; Boynton, John

    2008-01-01

    Conducting high resolution field microscopy with coupled laser spectroscopy that can be used to selectively analyze the surface chemistry of individual pixels in a scene is an enabling capability for next generation robotic and manned spaceflight missions, civil, and military applications. In the laboratory, we use a range of imaging and surface preparation tools that provide us with in-focus images, context imaging for identifying features that we want to investigate at high magnification, and surface-optical coupling that allows us to apply optical spectroscopic analysis techniques for analyzing surface chemistry particularly at high magnifications. The camera, hand lens, and microscope probe with scannable laser spectroscopy (CHAMP-SLS) is an imaging/spectroscopy instrument capable of imaging continuously from infinity down to high resolution microscopy (resolution of approx. 1 micron/pixel in a final camera format), the closer CHAMP-SLS is placed to a feature, the higher the resultant magnification. At hand lens to microscopic magnifications, the imaged scene can be selectively interrogated with point spectroscopic techniques such as Raman spectroscopy, microscopic Laser Induced Breakdown Spectroscopy (micro-LIBS), laser ablation mass-spectrometry, Fluorescence spectroscopy, and/or Reflectance spectroscopy. This paper summarizes the optical design, development, and testing of the CHAMP-SLS optics.

  9. Global Lithospheric Apparent Susceptibility Distribution Converted from Geomagnetic Models by CHAMP and Swarm Satellite Magnetic Measurements

    NASA Astrophysics Data System (ADS)

    Du, Jinsong; Chen, Chao; Xiong, Xiong; Li, Yongdong; Liang, Qing

    2016-04-01

    Recently, because of continually accumulated magnetic measurements by CHAMP satellite and Swarm constellation of three satellites and well developed methodologies and techniques of data processing and geomagnetic field modeling etc., global lithospheric magnetic anomaly field models become more and more reliable. This makes the quantitative interpretation of lithospheric magnetic anomaly field possible for having an insight into large-scale magnetic structures in the crust and uppermost mantle. Many different approaches have been utilized to understand the magnetized sources, such as forward, inversion, statistics, correlation analysis, Euler deconvolution, signal transformations etc. Among all quantitative interpretation methods, the directly converting a magnetic anomaly map into a magnetic susceptibility anomaly map proposed by Arkani-Hamed & Strangway (1985) is, we think, the most fast quantitative interpretation tool for global studies. We just call this method AS85 hereinafter for short. Although Gubbins et al. (2011) provided a formula to directly calculate the apparent magnetic vector distribution, the AS85 method introduced constraints of magnetized direction and thus corresponding results are expected to be more robust especially in world-wide continents. Therefore, in this study, we first improved the AS85 method further considering non-axial dipolar inducing field using formulae by Nolte & Siebert (1987), initial model or priori information for starting coefficients in the apparent susceptibility conversion, hidden longest-wavelength components of lithospheric magnetic field and field contaminations from global oceanic remanent magnetization. Then, we used the vertically integrated susceptibility model by Hemant & Maus (2005) and vertically integrated remanent magnetization model by Masterton et al. (2013) to test the validity of our improved method. Subsequently, we applied the conversion method to geomagnetic field models by CHAMP and Swarm satellite

  10. The Chandra Multi-Wavelength Project (ChaMP): A Serendipitous X-Ray Survey Using Chandra Archival Data

    NASA Technical Reports Server (NTRS)

    Wilkes, Belinda; Lavoie, Anthony R. (Technical Monitor)

    2000-01-01

    The launch of the Chandra X-ray Observatory in July 2000 opened a new era in X-ray astronomy. Its unprecedented, < 1" spatial resolution and low background is providing views of the X-ray sky 10-100 times fainter than previously possible. We have begun to carry out a serendipitous survey of the X-ray sky using Chandra archival data to flux limits covering the range between those reached by current satellites and those of the small area Chandra deep surveys. We estimate the survey will cover about 8 sq.deg. per year to X-ray fluxes (2-10 keV) in the range 10(exp -13) - 6(exp -16) erg cm2/s and include about 3000 sources per year, roughly two thirds of which are expected to be active galactic nuclei (AGN). Optical imaging of the ChaMP fields is underway at NOAO and SAO telescopes using g',r',z' colors with which we will be able to classify the X-ray sources into object types and, in some cases, estimate their redshifts. We are also planning to obtain optical spectroscopy of a well-defined subset to allow confirmation of classification and redshift determination. All X-ray and optical results and supporting optical data will be place in the ChaMP archive within a year of the completion of our data analysis. Over the five years of Chandra operations, ChaMP will provide both a major resource for Chandra observers and a key research tool for the study of the cosmic X-ray background and the individual source populations which comprise it. ChaMP promises profoundly new science return on a number of key questions at the current frontier of many areas of astronomy including solving the spectral paradox by resolving the CXRB, locating and studying high redshift clusters and so constraining cosmological parameters, defining the true, possibly absorbed, population of quasars and studying coronal emission from late-type stars as their cores become fully convective. The current status and initial results from the ChaMP will be presented.

  11. Properties of traveling atmospheric disturbances (TADs) inferred from CHAMP accelerometer observations

    NASA Astrophysics Data System (ADS)

    Bruinsma, Sean L.; Forbes, Jeffrey M.

    2009-02-01

    Densities derived from accelerometer measurements on the CHAMP satellite near 400 km are used to statistically establish characteristics of large-scale (>1000 km) traveling atmospheric disturbances (TADs). Only TADs that at least propagate from the auroral zone to the equator are analyzed here, and a total of 21 identifiable events are found over the years 2001 2007. The average speed of all TADs, regardless of local time, is 646 ± 122 ms-1. The average speeds on the dayside and nightside are 595 ± 127 ms-1 and 685 ± 106 ms-1, respectively, i.e., the speed appears to be 10% higher on average on the nightside. On six occasions TADs were only detected on the night side; however, TADs on the dayside often appear more distinctly in the data. Moreover, contrary to some theoretical expectations, dayside TADs do not dissipate more readily than night side TADs, although much less are detected between 8 20 solar local time. No clear dependence of TAD amplitude or phase speed with respect to Kp, or rate of increase of Kp, is found.

  12. Inversion of Magnetic Measurements of the CHAMP Satellite Over the Pannonian Basin

    NASA Technical Reports Server (NTRS)

    Kis, K. I.; Taylor, P. T.; Wittmann, G.; Toronyi, B.; Puszta, S.

    2011-01-01

    The Pannonian Basin is a deep intra-continental basin that formed as part of the Alpine orogeny. In order to study the nature of the crustal basement we used the long-wavelength magnetic anomalies acquired by the CHAMP satellite. The anomalies were distributed in a spherical shell, some 107,927 data recorded between January 1 and December 31 of 2008. They covered the Pannonian Basin and its vicinity. These anomaly data were interpolated into a spherical grid of 0.5 x 0.5, at the elevation of 324 km by the Gaussian weight function. The vertical gradient of these total magnetic anomalies was also computed and mapped to the surface of a sphere at 324 km elevation. The former spherical anomaly data at 425 km altitude were downward continued to 324 km. To interpret these data at the elevation of 324 km we used an inversion method. A polygonal prism forward model was used for the inversion. The minimum problem was solved numerically by the Simplex and Simulated annealing methods; a L2 norm in the case of Gaussian distribution parameters and a L1 norm was used in the case of Laplace distribution parameters. We INTERPRET THAT the magnetic anomaly WAS produced by several sources and the effect of the sable magnetization of the exsolution of hemo-ilmenite minerals in the upper crustal metamorphic rocks.

  13. Tidal signature of the mid-latitude ionospheric nighttime anomaly using CHAMP and GRACE observations

    NASA Astrophysics Data System (ADS)

    Xiong, Chao; Lühr, Hermann

    2014-05-01

    This paper presents a study on the tidal signatures of the mid-latitude summer nighttime anomaly (MSNA), also known as Weddell Sea anomaly in the southern hemisphere. The electron density observations by CHAMP and GRACE show clear MSNA structures in both hemispheres during local summer nighttime. A linear least squares algorithm for extracting the solar tidal components is utilized to examine the major tidal components affecting the variation of the electron density. In the southern hemisphere, we find a prominent eastward propagating wave-1 of electron density in the local time frame, which could be explained by the symmetric diurnal wave (D0) and a stationary planetary wave (SPW1) component. Conversely, in the northern hemisphere during local summer, a prominent eastward wave-2 can be found, which could be attributed to the diurnal eastward propagating wave (DE1) and a stationary planetary wave (SPW2) component. We are going to offer some explanations that may be responsible for the different appearance of the wave structures in the two hemispheres.

  14. Competition entre les phases ferromagnetique metallique et ordre de charges a l'interface de manganites a magnetoresistance colossale

    NASA Astrophysics Data System (ADS)

    Laverdiere, Jonathan

    transition metal-isolant est supprimee et la bicouche demeure isolante a toutes les temperatures. Dans la bicouche ayant une couche ferromagnetique de 4 nm, la transition metal-isolant est retrouvee sous l'application d'un champ magnetique de 1.5 T et une magnetoresistance de 50% est obtenue a 75K sous l'application d'un champ magnetique de 0.5 T. Un changement dans le champ magnetique necessaire a l'aimantation de la couche d'ordre de charges est egalement mesure, suggerant que la couche ferromagnetique induit des domaines ferromagnetiques dans la couche tampon. Ces resultats sont expliques par l'interaction mecanique dominant l'interface et favorisant la localisation des charges. L'anisotropie de la contrainte mecanique semble jouer un role supplementaire comparativement aux contraintes procurees par un substrat cubique. La rotation des octaedres ou la distorsion de Jahn-Teller, deux distorsions locales, pourraient contribuer a la tendance a localiser les charges. De plus, la phase isolante mesuree dans le Nd2/3Sr 1/3O3, normalement metallique, demeure plus sensible au champ magnetique que la phase isolante induite dans ce meme materiau par un substrat cubique isolant. La domination des contraintes mecaniques sur les influences ferromagnetiques suggere que cette influence soit le vecteur principal pour le controle de la separation de phases electroniques des manganites.

  15. Proprietes structurelles et magnetiques d'alliages de nanoparticules fabriquees par procedes lasers pour des applications biomedicales

    NASA Astrophysics Data System (ADS)

    Boyer, Paul

    mixture that is generated after multiple fragmentation events. Moreover, these particles had similar diameters and size distributions, allowing the comparison of their magnetic behaviour. Doing so, we observed a behaviour similar to the Slater-Pauling prediction of the magnetization of bulk materials as a function of the number of electrons of type d. However, important differences have also been observed, and the overall behaviour is closer to that of amorphous materials. The transition by zero of the spontaneous magnetization as a function of the number of d electrons occurs at Ni instead of the Ni 40Cu60 alloy. This indicates a loss of 0.6 µB , 35% of the magnetization of bulk Co at 0 K, in strong ferromagnetic materials. These modifications of the magnetization have been attributed to the multiple roles played by the oxide shell formed on the nanoparticles surface. Unlike what is reported in literature, the presence of oxidation not only reduces the magnetization by converting the external atomic layers in an antiferromagnetic material. The nanoparticles’ magnetization can also be improved by creating heterogeneous structures by introducing noble metals like gold into the particles. When the gold concentration becomes higher, the nanoparticles tend to repel the gold toward the surface in order to minimise the internal stress and to increase the particles stability to fragmentation. In this configuration similar to a core-shell structure, we have observed an increase of the core magnetization from 28 to 51 emu/g for an atomic fraction of Co68%Au32%. Gold then acts as an oxygen diffusion barrier and this structure was formed using laser processes that were not selective to the nature of the materials, as long as they tend to remain bonded to atoms of the same element. We have also observed that the magnetization of those hybrids cannot be explained by considering that the system’s magnetization occurs from the sum of the independent responses of each individual

  16. Family-Based HIV Preventive Intervention: Child Level Results from the CHAMP Family Program

    PubMed Central

    McBride, Cami K.; Baptiste, Donna; Traube, Dorian; Paikoff, Roberta L.; Madison-Boyd, Sybil; Coleman, Doris; Bell, Carl C.; Coleman, Ida; McKay, Mary M.

    2010-01-01

    SUMMARY Social indicators suggest that African American adolescents are in the highest risk categories of those contracting HIV/AIDS (CDC, 2001). The dramatic impact of HIV/AIDS on urban African American youth have influenced community leaders and policy makers to place high priority on programming that can prevent youth’s exposure to the virus (Pequegnat & Szapocznik, 2000). Program developers are encouraged to design programs that reflect the developmental ecology of urban youth (Tolan, Gorman-Smith, & Henry, 2003). This often translates into three concrete programmatic features: (1) Contextual relevance; (2) Developmental-groundedness; and (3) Systemic Delivery. Because families are considered to be urban youth’s best hope to grow up and survive multiple-dangers in urban neighborhoods (Pequegnat & Szapocznik, 2000), centering prevention within families may ensure that youth receive ongoing support, education, and messages that can increase their capacity to negotiate peer situations involving sex. This paper will present preliminary data from an HIV/AIDS prevention program that is contextually relevant, developmentally grounded and systematically-delivered. The collaborative HIV/AIDS Adolescent Mental Health Project (CHAMP) is aimed at decreasing HIV/AIDS risk exposure among a sample of African American youth living in a poverty-stricken, inner-city community in Chicago. This study describes results from this family-based HIV preventive intervention and involves 88 African American pre-adolescents and their primary caregivers. We present results for the intervention group at baseline and post intervention. We compare post test results to a community comparison group of youth. Suggestions for future research are provided. PMID:20852742

  17. Anti-Fatigue and Antioxidant Activity of the Polysaccharides Isolated from Millettiae speciosae Champ. Leguminosae

    PubMed Central

    Zhao, Xiao-Ning; Liang, Jia-Li; Chen, Han-Bin; Liang, Ye-Er; Guo, Hui-Zhen; Su, Ze-Ren; Li, Yu-Cui; Zeng, Hui-Fang; Zhang, Xiao-Jun

    2015-01-01

    Millettiae speciosae Champ. Leguminosae (MSC), is a well-known Chinese herb traditionally used as food material and medicine for enhancing physical strength. Our preliminary study found that the aqueous extract of this herb (MSE) had an anti-fatigue effect. In this paper, we further separated MSE into total polysaccharides (MSP) and supernatant (MSS) by alcohol precipitation, and explored which fraction was active for its anti-fatigue effect. Mice were orally administered with MSP or MSS at the doses of 200, 400, and 800 mg/kg for 20 days and the anti-fatigue effect was assessed by exhaustive swimming exercise (ESE). The biochemical parameters related to fatigue after ESE and the in vitro antioxidant activity of active fraction were determined. Our results showed that MSP, instead of MSS, significantly extended the swimming time to exhaustion (p < 0.05), indicating that MSP is responsible for the anti-fatigue effect of MSE. In addition, MSP treatment increased the levels of glucose (Glu) and muscle glycogen, whereas it decreased the accumulations of blood urea nitrogen (BUN) and lactic acid (Lac). Moreover, ESE increased the levels of creatine phosphokinase (CK), lactic dehydrogenase (LDH), and malondialdehyde (MDA) but reduced superoxide dismutase (SOD) and glutathione (GSH) in plasma. In contrast, MSP inhibited all the above changes relating to fatigue. Furthermore, an in vitro antioxidant test revealed that MSP dose-dependently scavenged ·OH and DPPH free radicals. Taken together, these findings strongly suggested that MSP was able to alleviate physical fatigue by increasing energy resources and decreasing accumulation of detrimental metabolites. The antioxidant activity may crucially contribute to the observed anti-fatigue effect of MSP. PMID:26506375

  18. Anti-Fatigue and Antioxidant Activity of the Polysaccharides Isolated from Millettiae speciosae Champ. Leguminosae.

    PubMed

    Zhao, Xiao-Ning; Liang, Jia-Li; Chen, Han-Bin; Liang, Ye-Er; Guo, Hui-Zhen; Su, Ze-Ren; Li, Yu-Cui; Zeng, Hui-Fang; Zhang, Xiao-Jun

    2015-10-21

    Millettiae speciosae Champ. Leguminosae (MSC), is a well-known Chinese herb traditionally used as food material and medicine for enhancing physical strength. Our preliminary study found that the aqueous extract of this herb (MSE) had an anti-fatigue effect. In this paper, we further separated MSE into total polysaccharides (MSP) and supernatant (MSS) by alcohol precipitation, and explored which fraction was active for its anti-fatigue effect. Mice were orally administered with MSP or MSS at the doses of 200, 400, and 800 mg/kg for 20 days and the anti-fatigue effect was assessed by exhaustive swimming exercise (ESE). The biochemical parameters related to fatigue after ESE and the in vitro antioxidant activity of active fraction were determined. Our results showed that MSP, instead of MSS, significantly extended the swimming time to exhaustion (p < 0.05), indicating that MSP is responsible for the anti-fatigue effect of MSE. In addition, MSP treatment increased the levels of glucose (Glu) and muscle glycogen, whereas it decreased the accumulations of blood urea nitrogen (BUN) and lactic acid (Lac). Moreover, ESE increased the levels of creatine phosphokinase (CK), lactic dehydrogenase (LDH), and malondialdehyde (MDA) but reduced superoxide dismutase (SOD) and glutathione (GSH) in plasma. In contrast, MSP inhibited all the above changes relating to fatigue. Furthermore, an in vitro antioxidant test revealed that MSP dose-dependently scavenged ·OH and DPPH free radicals. Taken together, these findings strongly suggested that MSP was able to alleviate physical fatigue by increasing energy resources and decreasing accumulation of detrimental metabolites. The antioxidant activity may crucially contribute to the observed anti-fatigue effect of MSP.

  19. The Midlatitude Summer Night Anomaly as observed by CHAMP and GRACE: Interpreted as tidal features

    NASA Astrophysics Data System (ADS)

    Xiong, Chao; Lühr, Hermann

    2014-06-01

    This paper presents a description of the Midlatitude Summer Night Anomaly (MSNA) in terms of solar tidal signatures, based on in situ observations from CHAMP (CHAllenging Minisatellite Payload) and GRACE (Gravity Recovery and Climate Experiment) during the solar minimum years 2008 and 2009. Our analysis is focusing on 40° to 60° magnetic latitude ranges in both hemispheres, where the reversed diurnal variations of the electron density are strongest. The results revealed that in the Southern Hemisphere the longitudinally symmetric tide D0 is particularly strong during December solstice. The well-known Weddell Sea Anomaly is caused by a simultaneous constructive interference of three components D0, DW2, and SPW1. During June solstice the eastward propagating tide DE1 is the strongest in the Northern Hemisphere, which causes a wave-2 longitudinal pattern. The two crests of the wave-2 pattern at nighttime correspond well with the MSNA feature in the Northern Hemisphere. The MSNA feature over the USA continent is particularly strong, which can be explained by the combined contributions of the components DE1, D0, and DW2. The diurnally varying difference in electron density between the USA East and West Coast can also be explained by the phase propagation of the DE1. A similar effect has also been observed in the Asian region. The peak electron densities of the tidal component D0 appear around 0700 LT and 2000 LT in the Southern and Northern Hemispheres, respectively. The time shift suggests that the two hemispheres move in antiphase up and down. The planetary wave SPW1 exhibits an electron density crest near longitude sectors where the dip equator reaches far into the summer hemisphere.

  20. IMF dependence of high-latitude thermospheric wind pattern derived from CHAMP cross-track measurements

    NASA Astrophysics Data System (ADS)

    Förster, M.; Rentz, S.; Köhler, W.; Liu, H.; Haaland, S. E.

    2008-06-01

    Neutral thermospheric wind pattern at high latitudes obtained from cross-track acceleration measurements of the CHAMP satellite above both North and South polar regions are statistically analyzed in their dependence on the Interplanetary Magnetic Field (IMF) direction in the GSM y-z plane (clock angle). We compare this dependency with magnetospheric convection pattern obtained from the Cluster EDI plasma drift measurements under the same sorting conditions. The IMF-dependency shows some similarity with the corresponding high-latitude plasma convection insofar that the larger-scale convection cells, in particular the round-shaped dusk cell for ByIMF+ (ByIMF-) conditions at the Northern (Southern) Hemisphere, leave their marks on the dominant general transpolar wind circulation from the dayside to the nightside. The direction of the transpolar circulation is generally deflected toward a duskward flow, in particular in the evening to nighttime sector. The degree of deflection correlates with the IMF clock angle. It is larger for ByIMF+ than for ByIMF- and is systematically larger (~5°) and appear less structured at the Southern Hemisphere compared with the Northern. Thermospheric cross-polar wind amplitudes are largest for BzIMF-/ByIMF- conditions at the Northern Hemisphere, but for BzIMF-/ByIMF+ conditions at the Southern because the magnetospheric convection is in favour of largest wind accelerations over the polar cap under these conditions. The overall variance of the thermospheric wind magnitude at Southern high latitudes is larger than for the Northern. This is probably due to a larger "stirring effect" at the Southern Hemisphere because of the larger distance between the geographic and geomagnetic frameworks.

  1. Spin resonance transport properties of a single Au atom in S-Au-S junction and Au-Au-Au junction

    NASA Astrophysics Data System (ADS)

    Fangyuan, Wang; Guiqin, Li

    2016-07-01

    The spin transport properties of S-Au-S junction and Au-Au-Au junction between Au nanowires are investigated with density functional theory and the non-equilibrium Green's function. We mainly focus on the spin resonance transport properties of the center Au atom. The breaking of chemical bonds between anchor atoms and center Au atom significantly influences their spin transmission characteristics. We find the 0.8 eV orbital energy shift between anchor S atoms and the center Au atom can well protect the spin state stored in the S-Au-S junction and efficiently extract its spin state to the current by spin resonance mechanism, while the spin interaction of itinerant electrons and the valence electron of the center Au atom in the Au-Au-Au junction can extract the current spin information into the center Au atom. Fermi energy drift and bias-dependent spin filtering properties of the Au-Au-Au junction may transform information between distance, bias, and electron spin. Those unique properties make them potential candidates for a logical nanocircuit. Project supported by the National Basic Research Program of China (Grants No. 2011CB921602) and the National Natural Science Foundation of China (Grants No. 20121318158).

  2. Thermosphere density variations due to the 15-24 April 2002 solar events from CHAMP/STAR accelerometer measurements

    NASA Astrophysics Data System (ADS)

    Forbes, Jeffrey M.; Lu, Gang; Bruinsma, Sean; Nerem, Steven; Zhang, Xiaoli

    2005-12-01

    Thermosphere densities near 410 km altitude between ±87° latitude and near 0430 and 1530 local time from the accelerometer experiment on the CHAMP satellite are used to elucidate the response to three coronal mass ejections occurring on 17, 19, and 21 April 2002. Comparisons of the global responses with the NRLMSISE00 empirical model and the NCAR TIEGCM are performed and interpreted. An enhanced daytime response in comparison to TIEGCM on 17 April is found that is suggestive of preconditioning of the atmosphere due to enhanced solar EUV fluxes maximizing on 13 April. Out of several solar wind parameters and geophysical indices that were examined, the highest correlation with thermosphere densities occurred with respect to the magnitude of the interplanetary magnetic field as measured by the ACE spacecraft. Wave-like structures with scales ranging from 100s to 1000s of kilometers are also revealed in the CHAMP data. These structures are primarily a nighttime phenomena, and the associated total variance is correlated with magnetic activity throughout the 15-24 April 2002 period. The NCAR TIEGCM was utilized to provide the basis for interpreting the equatorward propagation of large-scale traveling atmospheric disturbance (TADs). Following a sudden increase in magnetic activity and high-latitude heating, TADs were launched from both hemispheres, traveled toward the equator with phase speeds of order 800 m s-1, constructively interfered near the equator to produce a total density perturbation of ˜20%, and then passed through each other and into the opposite hemisphere. Perspectives on future applications of CHAMP accelerometer data to elucidate magnetic storm-related perturbations of the thermosphere are outlined.

  3. The Italian software for GPS radio occultation: validation using COSMIC and CHAMP data

    NASA Astrophysics Data System (ADS)

    Perona, G.; Notarpietro, R.

    2009-04-01

    The GPS Radio Occultation (RO) is a remote sensing technique for the profiling of atmospheric parameters. It is based on the inversion of L1 and L2 GPS signals collected on-board a Low Earth Orbit (LEO) platform, when the transmitter rises or sets beyond the Earth's limb. The relative movement of both satellites allows a "quasi" vertical atmospheric scan and the profiles extracted using this technique are characterized by a high vertical resolution and a high accuracy. The RO technique is operatively applied for meteorological purposes since such observations can easily be assimilated into Numerical Weather Prediction models. Anyway it is very useful also for climatological purposes, for gravity wave observations and for Space Weather applications. Actually, three operative satellite missions are carrying on-board GPS receivers for RO purposes: the German CHAMP satellite, the European METOP-1 mission and the USA/Taiwan COSMIC constellation. Several other missions are planned for the next future. In particular, during the 2009 Spring season, the Indian OCEANSAT-2 mission carrying on-board the Italian ROSA (Radio Occultation Sounder of the Atmosphere) GPS receiver is expected to be launched. In the framework of this opportunity, the Italian Space Agency (ASI) founded a pool of Italian Universities and Research Centers for the implementation of the overall (and state-of-the-art) RO processing chain which is called ROSA-ROSSA (ROSA-Research and Operational Satellite and Software Activities). The ROSA-ROSSA will be integrated in the operative ROSA Ground Segment by an Italian Software farm (INNOVA, located in Matera, Italy), and this ground segment will operate in Italy (at the ASI Space Geodesy Center, near Matera) and in India (at the Indian National Remote Sensing Agency, near Hyderabad) starting from the 2009 Spring season. The "Base" version of the ROSA-ROSSA software was delivered to the Industrial partner at the end of 2008 for its integration inside the Italian

  4. Investigation of the crust of the Pannonian Basin, Hungary using low-altitude CHAMP horizontal magnetic gradient anomalies

    NASA Astrophysics Data System (ADS)

    Taylor, P. T.; Kis, K. I.; Puszta, S.; Wittman, G.; Kim, H.; Toronyi, B.

    2011-12-01

    The Pannonian Basin is a deep intracontinental basin that formed as part of the Alpine orogeny. It is some 600 by 500 km in area and centered on Hungary. This region was chosen since it has one of the thinnest continental crusts in Europe and is the location of complex tectonic structures. In order to study the nature of the crustal basement we used the long-wavelength magnetic anomalies acquired by the CHAMP satellite. The SWARM constellation, scheduled to be launched next year, will have two lower altitude satellites flying abreast, with a separation of between ca. 150 to 200 km. to record the horizontal magnetic gradient. Since the CHAMP satellite has been in orbit for eight years and has obtained an extensive range of data, both vertically and horizontally there is a large enough data base to compute the horizontal magnetic gradients over the Pannonian Basin region using these many CHAMP orbits. We computed a satellite magnetic anomaly map, using the spherical-cap method of Haines (1985), the technique of Alsdorf et al. (1994) and from spherical harmonic coefficients of MF6 (Maus et al., 2008) employing recent and lowest altitude CHAMP data. We then computed the horizontal magnetic anomaly gradients (Kis and Puszta, 2006) in order to determine how these component data will improve our interpretation and to preview what the SWARM mission will reveal with reference to the horizontal gradient anomalies. The gradient amplitude of an 1000 km northeast-southwest profile through our horizontal component anomaly map varied from 0 to 0.025 nT/km with twin positive anomalies (0.025 and 0.023 nT/km) separated by a sharp V-shaped anomaly gradient to 0 nT/km between the two highs. Horizontal gradients indicate major magnetization boundaries in the crust (Dole and Jordan, 1978 and Cordell and Grauch, 1985). Our gradient anomaly was modeled with a two-dimensional body and this anomaly indicates a lateral variation of some 200 km. The model correlates with a 200 km area of

  5. Interpretation of CHAMP Magnetic Anomaly Data over the Pannonian Basin Region Using Lower Altitude Horizontal Gradient Data

    NASA Technical Reports Server (NTRS)

    Taylor, P. T.; Kis, K. I.; Wittmann, G.

    2013-01-01

    The ESA SWARM mission will have three earth orbiting magnetometer bearing satellites one in a high orbit and two side-by-side in lower orbits. These latter satellites will record a horizontal magnetic gradient. In order to determine how we can use these gradient measurements for interpretation of large geologic units we used ten years of CHAMP data to compute a horizontal gradient map over a section of southeastern Europe with our goal to interpret these data over the Pannonian Basin of Hungary.

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

    SciTech Connect

    Ohno, S.; Shimakura, H.; Tahara, S.; Okada, T.

    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.

  7. Detection of Meteoric Dust in the Mesosphere by the CHAMPS Rockets

    NASA Astrophysics Data System (ADS)

    Robertson, S. H.; Dickson, S.; Horanyi, M.; Sternovsky, Z.; Friedrich, M.; Janches, D.; Williams, B.

    2012-12-01

    In October 2011, two CHAMPS (charge and mass of meteoric smoke particles) sounding rockets were launched into the polar mesosphere, each carrying an electrostatic multichannel mass analyzer for charged aerosol particles. The payloads also carried Faraday rotation antennas and an array of plasma probes for determining electron and ion densities and the payload charging potential. The launches were from the Andøya Rocket Range, Norway, following the end of the noctilucent cloud season. One night launch (11 October 21:50 UT) and one day launch (13 October 13:50 UT) helped to elucidate the role of photo-detachment and photoelectric charging. Charge layers in two distinct altitude ranges were observed on both flights: a high altitude negative charge layer between 77 - 93 km, and low altitude positive and negative charge layers that coexist from 63 - 73 km. In a layer spanning approximately 77 - 93 km, the nighttime data show negatively charged particles with masses in the range 500 - 2,000 amu, 2,000 - 8,000 amu and 8,000 - 20,000 amu. These mass ranges occur together each with a particle density of ~400 cm-3. In this altitude range, the Faraday rotation data show that the electron density rises from about 103 cm-3 to about 105 cm-3 indicating that there are sufficient electrons for the fraction of dust that is charged to be near 100%. This negative layer from 77 - 93 km was also present during the day with approximately the same number density. From about 73 km to 63 km where data acquisition ended, the nighttime data show both positive and negative particles in the 500 - 8,000 amu mass ranges with densities of 2,500 cm-3 and 500 cm-3, respectively. The heavier particles have peak densities at lower altitudes. In this altitude range, the dust densities exceed the electron density. These layers are again present in the daytime data with approximately the same altitude distribution; however, the number densities for the positive particles are reduced by a factor of ~3

  8. /Au Back Contacts

    NASA Astrophysics Data System (ADS)

    Paudel, Naba R.; Compaan, Alvin D.; Yan, Yanfa

    2014-08-01

    We report on the fabrication and characterization of CdTe thin-film solar cells with Cu-free MoO3- x /Au back contacts. CdTe solar cells with sputtered CdTe absorbers of thicknesses from 0.5 to 1.75 μm were fabricated on Pilkington SnO2:F/SnO2-coated soda-lime glasses coated with a 60- to 80-nm sputtered CdS layer. The MoO3- x /Au back contact layers were deposited by thermal evaporation. The incorporation of MoO3- x layer was found to improve the open circuit voltage ( V OC) but reduce the fill factor of the ultrathin CdTe cells. The V OC was found to increase as the CdTe thickness increased.

  9. Magnetoresistance of Au films

    DOE PAGESBeta

    Zhang, D. L.; Song, X. H.; Zhang, X.; Zhang, Xiaoguang

    2014-12-10

    Measurement of the magnetoresistance (MR) of Au films as a function of temperature and film thickness reveals a strong dependence on grain size distribution and clear violation of the Kohler s rule. Using a model of random resistor network, we show that this result can be explained if the MR arises entirely from inhomogeneity due to grain boundary scattering and thermal activation of grain boundary atoms.

  10. Un champ semantique: les noms d'appartenance raciale au Honduras britannique (A Semantic Field: Names of Racial Identity in the British Honduras)

    ERIC Educational Resources Information Center

    Tabouret-Keller, Andree

    1975-01-01

    This article studies the problem of social identity among six different racial groups in the British Honduras, focusing on what the groups call themselves and what others call them, and on the semantic field of these terms, i.e. the socio-cultural values they represent. (Text is in French.) (AM)

  11. Antibacterial Au nanostructured surfaces

    NASA Astrophysics Data System (ADS)

    Wu, Songmei; Zuber, Flavia; Brugger, Juergen; Maniura-Weber, Katharina; Ren, Qun

    2016-01-01

    We present here a technological platform for engineering Au nanotopographies by templated electrodeposition on antibacterial surfaces. Three different types of nanostructures were fabricated: nanopillars, nanorings and nanonuggets. The nanopillars are the basic structures and are 50 nm in diameter and 100 nm in height. Particular arrangement of the nanopillars in various geometries formed nanorings and nanonuggets. Flat surfaces, rough substrate surfaces, and various nanostructured surfaces were compared for their abilities to attach and kill bacterial cells. Methicillin-resistant Staphylococcus aureus, a Gram-positive bacterial strain responsible for many infections in health care system, was used as the model bacterial strain. It was found that all the Au nanostructures, regardless their shapes, exhibited similar excellent antibacterial properties. A comparison of live cells attached to nanotopographic surfaces showed that the number of live S. aureus cells was <1% of that from flat and rough reference surfaces. Our micro/nanofabrication process is a scalable approach based on cost-efficient self-organization and provides potential for further developing functional surfaces to study the behavior of microbes on nanoscale topographies.We present here a technological platform for engineering Au nanotopographies by templated electrodeposition on antibacterial surfaces. Three different types of nanostructures were fabricated: nanopillars, nanorings and nanonuggets. The nanopillars are the basic structures and are 50 nm in diameter and 100 nm in height. Particular arrangement of the nanopillars in various geometries formed nanorings and nanonuggets. Flat surfaces, rough substrate surfaces, and various nanostructured surfaces were compared for their abilities to attach and kill bacterial cells. Methicillin-resistant Staphylococcus aureus, a Gram-positive bacterial strain responsible for many infections in health care system, was used as the model bacterial strain. It

  12. Surface morphology and optical properties of porphyrin/Au and Au/porphyrin/Au systems

    PubMed Central

    2013-01-01

    Porphyrin/Au and Au/porphyrin/Au systems were prepared by vacuum evaporation and vacuum sputtering onto glass substrate. The surface morphology of as-prepared systems and those subjected to annealing at 160°C was studied by optical microscopy, atomic force microscopy, and scanning electron microscopy techniques. Absorption and luminescence spectra of as-prepared and annealed samples were measured. Annealing leads to disintegration of the initially continuous gold layer and formation of gold nanoclusters. An amplification of Soret band magnitude was observed on the Au/meso-tetraphenyl porphyrin (TPP) system in comparison with mere TPP. Additional enhancement of luminescence was observed after the sample annealing. In the case of sandwich Au/porphyrin/Au structure, suppression of one of the two porphyrins’ luminescence maxima and sufficient enhancement of the second one were observed. PMID:24373347

  13. Détermination de régimes transitoires des moteurs à induction par une nouvelle méthode de couplage des champs magnétiques du stator et du rotor

    NASA Astrophysics Data System (ADS)

    Bock, J. P.; Laporte, B.; Vinsard, G.

    1995-10-01

    A model allowing the effective computation of the transient behaviour of deep squirrel cage induction motors is detailed. The principle of the model is that the coupling between the rotor and the stator is made only by the fundamental space harmonic, the other harmonics are forced to vanish through the air gap. The main interest is that in the time step method only the fundamental space harmonic has to be transferred, which allows larger steps than in a punctual transfer. This method can be used when non linearities exist but it is detailed in the paper in the linear case. Nous présentons la modélisation d'un moteur à induction à cage profonde dont la vitesse est donnée et que l'on alimente, à partir d'un instant donné, par des courants qui sont des fonctions connues du temps. Les champs statoriques et rotoriques sont couplés par leur premier harmonique d'espace. L'intérêt de cette méthode est que seul le premier harmonique d'espace est transporté dans le suivi simultané du mouvement et de l'évolution des courants, ce qui autorise des rotations élémentaires plus importantes et donc un temps de calcul nettement réduit. La méthode, généralisable au cas non linéaire, est développée ici dans le cas linéaire.

  14. Magnetoresistance of Au films

    SciTech Connect

    Zhang, D. L. Song, X. H.; Zhang, X.; Zhang, X.-G.

    2014-12-14

    Classical magnetoresistance (MR) in nonmagnetic metals are conventionally understood in terms of the Kohler rule, with violation usually viewed as anomalous electron transport, in particular, as evidence of non-Fermi liquid behavior. Measurement of the MR of Au films as a function of temperature and film thickness reveals a strong dependence on grain size distribution and clear violation of the Kohler rule. Using a model of random resistor network, we show that this result can be explained if the MR arises entirely from inhomogeneity due to grain boundary scattering and thermal activation of grain boundary atoms. Consequently, the Kohler rule should not be used to distinguish normal and anomalous electron transport in solids.

  15. Au103(SR)45, Au104(SR)45, Au104(SR)46 and Au105(SR)46 nanoclusters

    NASA Astrophysics Data System (ADS)

    Dass, Amala; Nimmala, Praneeth Reddy; Jupally, Vijay Reddy; Kothalawala, Nuwan

    2013-11-01

    High resolution ESI mass spectrometry of the ``22 kDa'' nanocluster reveals the presence of a mixture containing Au103(SR)45, Au104(SR)45, Au104(SR)46, and Au105(SR)46 nanoclusters, where R = -CH2CH2Ph. MALDI TOF MS data confirm the purity of the sample and a UV-vis spectrum shows minor features. Au102(SC6H5COOH)44, whose XRD crystal structure was recently reported, is not observed. This is due to ligand effects, because the 102 : 44 composition is produced using aromatic ligands. However, the 103-, 104- and 105-atom nanoclusters, protected by -SCH2CH2Ph and -SC6H13 ligands, are at or near 58 electron shell closing.High resolution ESI mass spectrometry of the ``22 kDa'' nanocluster reveals the presence of a mixture containing Au103(SR)45, Au104(SR)45, Au104(SR)46, and Au105(SR)46 nanoclusters, where R = -CH2CH2Ph. MALDI TOF MS data confirm the purity of the sample and a UV-vis spectrum shows minor features. Au102(SC6H5COOH)44, whose XRD crystal structure was recently reported, is not observed. This is due to ligand effects, because the 102 : 44 composition is produced using aromatic ligands. However, the 103-, 104- and 105-atom nanoclusters, protected by -SCH2CH2Ph and -SC6H13 ligands, are at or near 58 electron shell closing. Electronic supplementary information (ESI) available. See DOI: 10.1039/c3nr03872f

  16. Determination of relative sensitivity factors during secondary ion sputtering of silicate glasses by Au+, Au2+ and Au3+ ions.

    PubMed

    King, Ashley; Henkel, Torsten; Rost, Detlef; Lyon, Ian C

    2010-01-01

    In recent years, Au-cluster ions have been successfully used for organic analysis in secondary ion mass spectrometry. Cluster ions, such as Au(2)(+) and Au(3)(+), can produce secondary ion yield enhancements of up to a factor of 300 for high mass organic molecules with minimal sample damage. In this study, the potential for using Au(+), Au(2)(+) and Au(3)(+) primary ions for the analysis of inorganic samples is investigated by analyzing a range of silicate glass standards. Practical secondary ion yields for both Au(2)(+) and Au(3)(+) ions are enhanced relative to those for Au(+), consistent with their increased sputter rates. No elevation in ionization efficiency was found for the cluster primary ions. Relative sensitivity factors for major and trace elements in the standards showed no improvement in quantification with Au(2)(+) and Au(3)(+) ions over the use of Au(+) ions. Higher achievable primary ion currents for Au(+) ions than for Au(2)(+) and Au(3)(+) allow for more precise analyses of elemental abundances within inorganic samples, making them the preferred choice, in contrast to the choice of Au(2)(+) and Au(3)(+) for the analysis of organic samples. The use of delayed secondary ion extraction can also boost secondary ion signals, although there is a loss of overall sensitivity.

  17. Droplet-based magnetic bead immunoassay using microchannel-connected multiwell plates (μCHAMPs) for the detection of amyloid beta oligomers.

    PubMed

    Park, Min Cheol; Kim, Moojong; Lim, Gun Taek; Kang, Sung Min; An, Seong Soo A; Kim, Tae Song; Kang, Ji Yoon

    2016-06-21

    Multiwell plates are regularly used in analytical research and clinical diagnosis but often require laborious washing steps and large sample or reagent volumes (typically, 100 μL per well). To overcome such drawbacks in the conventional multiwell plate, we present a novel microchannel-connected multiwell plate (μCHAMP) that can be used for automated disease biomarker detection in a small sample volume by performing droplet-based magnetic bead immunoassay inside the plate. In this μCHAMP-based immunoassay platform, small volumes (30-50 μL) of aqueous-phase working droplets are stably confined within each well by the simple microchannel structure (200-300 μm in height and 0.5-1 mm in width), and magnetic beads are exclusively transported into an adjacent droplet through the oil-filled microchannels assisted by a magnet array aligned beneath and controlled by a XY-motorized stage. Using this μCHAMP-based platform, we were able to perform parallel detection of synthetic amyloid beta (Aβ) oligomers as a model analyte for the early diagnosis of Alzheimer's disease (AD). This platform easily simplified the laborious and consumptive immunoassay procedure by achieving automated parallel immunoassay (32 assays per operation in 3-well connected 96-well plate) within 1 hour and at low sample consumption (less than 10 μL per assay) with no cumbersome manual washing step. Moreover, it could detect synthetic Aβ oligomers even below 10 pg mL(-1) concentration with a calculated detection limit of ∼3 pg mL(-1). Therefore, the μCHAMP and droplet-based magnetic bead immunoassay, with the combination of XY-motorized magnet array, would be a useful platform in the diagnosis of human disease, including AD, which requires low consumption of the patient's body fluid sample and automation of the entire immunoassay procedure for high processing capacity. PMID:27185215

  18. Blocage de Coulomb dans une boite quantique laterale contenant un faible nombre d'electrons

    NASA Astrophysics Data System (ADS)

    Gould, Charles

    Dans ce travail on utilise une nouvelle geometrie pour augmenter le controle sur le nombre d'electrons contenus dans une boite quantique laterale, et ainsi atteindre un regime de petit nombre d'electrons. Ces echantillons permettent une etude du blocage de Coulomb quand les electrons sont injectes a partir d'un gaz electronique a deux dimensions (2DEG). Les mesures a faible champ magnetique demontrent la grande flexibilite des echantillons et montrent que l'on peut faire varier le nombre d'electrons dans une boite quantique a partir de plus de 40 electrons jusqu'a un seul electron, ce qui est assez courant dans les boites quantiques verticales, mais ce qui n'avait jamais ete reussi dans une boite quantique laterale. Nos resultats montrent egalement que dans les boites quantiques laterales il est possible de determiner le spin du niveau qui participe au transport a l'aide du phenomene de blocage de spin. De plus, dans certaines circonstances il est meme possible de determiner le spin total de la boite quantique, ce qui peut avoir des applications pratiques dans des domaines tels l'informatique quantique. Les mesures dans le regime de renversement de spin a un champ magnetique plus eleve montrent l'importance des correlations electrons---electrons dans ces boites quantiques, qui menent a des depolarisations et a des structures de spins qui ont un effet sur le transport. En particulier, ces correlations menent a l'existence de niveaux excites de basse energie qui causent une dependance anormale de l'amplitude des pics de blocage de Coulomb en fonction de la temperature. Nos experiences demontrent egalement la possibilite d'utiliser ces boites quantiques comme sondes pour etudier les proprietes du bord d'un 2DEG. Une voie de recherche a etre exploree.

  19. Evolution des quasiparticules nodales du cuprate supraconducteur YBa2Cu3Oy en conductivite thermique

    NASA Astrophysics Data System (ADS)

    Rene de Cotret, Samuel

    Ce memoire presente des mesures de conductivite thermique sur les supraconducteurs YBCO et Tl-2201 afin de statuer sur la presence possible d'un point critique quantique (QCP) dans le diagramme de phase de cuprates. Ce point critique quantique serait a l'origine de la reconstruction de la surface de Fermi, d'un large cylindre de trous en de petites poches de trous et d'electrons. La conductivite thermique dans le regime T → 0 permet d'extraire une quantite purement electronique liee aux vitesses de Fermi et du gap, au noeud. Une discontinuite dans cette quantite pourrait signaler la traversee du dopage critique qui reconstruit la surface de Fermi. Plusieurs sondes experimentales distinguent une transition de phase ou un crossover a T* a temperature finie. D'autres sondes mettent en evidence une transition de phase sous l'effet d'un champ magnetique. La presence ou non de cet ordre, a temperature et champ magnetique nul questionne la communaute depuis plusieurs annees. Dans cette etude, nous detectons une variation brusque de kappa0/T a p = 0.18 dans YBCO et a p = 0.20 dans Tl-2201. Ces sauts sont interpretes comme un signe de la transition a temperature nulle et sont en faveur d'un QCP. Le manque de donnees d'un meme materiau a ces dopages ne permet pas de valider hors de tout doute l'existence d'un point critique quantique. Le modele theorique YRZ decrit aussi bien les donnees de conductivite thermique. Des pistes de travaux experimentaux a poursuivre sont proposees pour determiner la presence ou non du QCP de facon franche. Mots-cles : Supraconducteurs, cuprates, conductivite thermique, point critique quantique.

  20. Manifestation of the petrogeneration zones of Northern and the Bering seas in ground magnetic anomalies and anomalies of satellite Champ

    NASA Astrophysics Data System (ADS)

    Litvinova, Tamara; Krasinsky, Egor; Petrova, Alevtina; Demina, Irina

    2010-05-01

    The purpose of this paper are showed results of studying of specificity of a deep structure of zones of petrogeneration Northern and the Bering seas on aeromagnetic and satellite magnetometric datas. Research lateral and vertical heterogeneitys an earth's crust of Northern sea is carried out on the basis of the analysis of measurements of satellite Champ at height of 100 km and the digital database created on materials of sea shooting of a geomagnetic field, executed on non-magnetic schooner "Zarya". On sea measurements in Northern sea through large oil fields and gas ( Frigg, Ekofisk, Forties trough, Leman, etc.). Geomagnetic sections for an interval of depths from 1 up to 30 km are constructed. It has allowed to study character of distribution of magnetization of breeds of a cover, horizontal lamination intracore layers of an earth's crust and to allocate in zones petrogeneration synvertical fluidoconduct zones the channels described by alternation of not magnetic and low-magnetic layers. They were showed on geomagnetic sections as permeable zones quasi- laminated structures with the lowered magnetic properties in an interval of depths from 8 up to 28 km. Comparison to a map of the magnetic anomalies measured at height of 100 km by satellite Champ, has shown, that areas of the greatest petrocongestions North Sea рифта at height of 100 km are dated for a zone of gradients and a minimum of northeast displacement of regional anomalies of western and east blocks of Northern sea. It corresponds to representations about an orientation of a fissuring zone and the increased size of a geothermal gradient North Sea rift and is corresponded position allocated on hydromagnetic structures deep fluidoconduct channels. Thus, distribution to water areas of deposits of deposits is emphasized not only low-magnetic areas in a thickness of a sedimentary cover where they are directly located, but also by not magnetic lenses in breeds of the base spreading it in intervals of

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

    SciTech Connect

    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. ||||||||[Universities Space Sciences Research Association

    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. Au20: A Tetrahedral Cluster

    SciTech Connect

    Li, Jun; Li, Xi; Zhai, Hua Jin; Wang, Lai S.

    2003-02-07

    Photoelectron spectroscopy revealed that a 20 atom gold cluster has an extremely large energy gap, which is even greater than that of C60, and an electron affinity comparable with that of C60. This observation suggests that the Au20 cluster must be extremely stable and chemically inert. Using relativistic density functional calculations, we found that Au20 possesses a remarkable tetrahedral structure, which is a fragment of the bulk face-centered cubic lattice of gold with a small structural relaxation. Au20 is thus a true cluster molecule, while at the same time it is exactly part of the bulk, but with very different properties. The tetrahedral Au20 may possess interesting catalytic properties and may be synthesized in bulk quantity or assembled on non-interacting surfaces.

  3. Transcriptome Analysis of Storage Roots and Fibrous Roots of the Traditional Medicinal Herb Callerya speciosa (Champ.) ScHot

    PubMed Central

    Lei, Ming; Li, Li; Fu, Yunliu; Wang, Zhunian; Ao, Mengfei; Li, Zhiying

    2016-01-01

    Callerya speciosa (Champ.) ScHot is a woody perennial plant in Fabaceae, the roots of which are used medicinally. The storage roots of C. speciosa are derived from fibrous roots, but not all fibrous roots can develop into storage roots. To detect key genes involved in storage roots formation, we performed Illumina sequencing of the C. speciosa storage roots and fibrous roots. De novo assembly resulted in 161,926 unigenes, which were subsequently annotated by BLAST, GO and KEGG analyses. After expression profiling, 4538 differentially expressed genes were identified. The KEGG pathway enrichment analysis revealed changes in the biosynthesis of cytokinin, phenylpropanoid, starch, sucrose, flavone and other secondary metabolites. Transcription factor-related differentially expressed genes (DEGs) were also identified, including such gene families as GRAS, COL, MIKC, ERF, LBD, and NAC. The DEGs related to light signaling, starch, sugar, photohormones and cell wall-loosening might be involved in the formation of storage roots. This study provides the first transcriptome profiling of C. speciosa roots, data that will facilitate future research of root development and metabolites with medicinal value as well as the breeding of C. speciosa. PMID:27486800

  4. A Field-Based Testing Protocol for Assessing Gross Motor Skills in Preschool Children: The CHAMPS Motor Skills Protocol (CMSP)

    PubMed Central

    Williams, Harriet G.; Pfeiffer, Karin A.; Dowda, Marsha; Jeter, Chevy; Jones, Shaverra; Pate, Russell R.

    2010-01-01

    The purpose of the study was to develop a valid and reliable tool for use in assessing motor skills in preschool children in field based settings. The development of the CHAMPS (Children’s Activity and Movement in Preschool Study) Motor Skills Protocol (CMSP) included evidence of its reliability and validity for use in field-based environments as part of large epidemiological studies. Following pilot work, 297 children (3-5 years old) from 22 preschools were tested using the final version of the CMSP and the TGMD-2. Reliability of the CMSP and interobserver reliability were determined using intraclass correlation procedures (ICC; ANOVA). Concurrent validity was assessed using Pearson correlation coefficients to compare the CMSP to the original Test of Gross Motor Development (2nd Edition) (TGMD-2). Results indicated that test reliability, interobserver reliability and validity coefficients were all high, generally above R/r = 0.90. Significant age differences were found. Outcomes indicate that the CMSP is an appropriate tool for assessing motor development of 3-, 4-, and 5-year-old children in field-based settings that are consistent with large-scale trials. PMID:21532999

  5. Field-aligned current associated with low-latitude plasma blobs as observed by the CHAMP satellite

    NASA Astrophysics Data System (ADS)

    Park, J.; Lühr, H.; Stolle, C.; Rother, M.; Min, K. W.; Michaelis, I.

    2010-03-01

    Here we give two examples of low-latitude plasma blobs accompanied by linearly polarized perpendicular magnetic deflections which imply that associated field-aligned currents (FACs) have a 2-D sheet structure located at the blob walls. The estimated FAC density is of the order of 0.1 μA/m2. The direction of magnetic deflections points westward of the magnetic meridian and there is a linear correlation between perpendicular and parallel variations. All these properties are similar to those of equatorial plasma bubbles (EPBs). According to CHAMP observations from August 2000 to July 2004, blobs show except for these two good examples no clear signatures of 2-D FAC sheets at the walls. Generally, perpendicular magnetic deflections inside blobs are weaker than inside EPBs on average. Our results are consistent with existing theories: if a blob exists, (1) a significant part of EPB FAC will be closed through it, exhibiting similar perpendicular magnetic deflection inside EPBs and blobs, (2) the FAC closure through blobs leads to smaller perpendicular magnetic deflection at its poleward/downward side, and (3) superposition of different FAC elements might result in a complex magnetic signature around blobs.

  6. Large-scale traveling atmospheric disturbances (LSTADs) in the thermosphere inferred from CHAMP, GRACE, and SETA accelerometer data

    NASA Astrophysics Data System (ADS)

    Bruinsma, Sean L.; Forbes, Jeffrey M.

    2010-08-01

    Densities derived from accelerometer measurements on the GRACE, CHAMP, and Air Force/SETA satellites near 490, 390, and 220 km, respectively, are used to elucidate global-scale characteristics of traveling atmospheric disturbances (TADs). Several characteristics elucidated in numerical simulations are confirmed in this study, namely: (1) propagation speeds increase from the lower thermosphere to the upper thermosphere; (2) propagation to the equator and even into the opposite hemisphere can occur; (3) greater attenuation of TADs occurs during daytime and at higher levels of solar activity (i.e., more wave activity during nighttime and solar minimum), presumably due to the greater influence of ion drag. In addition, we find that the occurrence of significant TAD activity emanating from the auroral regions does not reflect a clear relation with the level of planetary magnetic activity as measured by Kp. There is also evidence of waves originating in the tropics, presumably due to convective sources; to some extent this may contribute to the Kp and solar flux relationships noted above. Further elucidation of local time, season, and altitude dependences of TAD propagation characteristics may be forthcoming from density measurements from the GOCE and Swarm missions.

  7. Near-equatorial Pi2 and Pc3 waves observed by CHAMP and on SAMBA/MAGDAS stations

    NASA Astrophysics Data System (ADS)

    Cuturrufo, F.; Pilipenko, V.; Heilig, B.; Stepanova, M.; Lühr, H.; Vega, P.; Yoshikawa, A.

    2015-02-01

    We have examined simultaneous ULF activity in the Pi2 and Pc3 bands at the near-equatorial magnetic stations in South America from SAMBA and MAGDAS arrays and low-orbiting CHAMP satellite during its passage over this meridional network. At the nighttime, both Pi2 and Pc3 waves in the upper ionosphere and on the ground are nearly of the same magnitude and in-phase. At the same time, the daytime Pc3 pulsations on the ground and in space are nearly out-of-phase. Comparison of observational results with the theoretical notions on the MHD wave interaction with the system ionosphere-atmosphere-ground suggests that nighttime low-latitude Pi2 and Pc3 wave signatures are produced by magnetospheric fast compressional mode. The daytime near-equatorial Pc3 waves still resist a quantative interpretation. These waves may be produced by a combination of two mechanisms: compressional mode leakage through the ionosphere, and by oscillatory ionospheric current spreading towards equatorial latitudes.

  8. Transcriptome Analysis of Storage Roots and Fibrous Roots of the Traditional Medicinal Herb Callerya speciosa (Champ.) ScHot.

    PubMed

    Xu, Li; Wang, Jiabin; Lei, Ming; Li, Li; Fu, Yunliu; Wang, Zhunian; Ao, Mengfei; Li, Zhiying

    2016-01-01

    Callerya speciosa (Champ.) ScHot is a woody perennial plant in Fabaceae, the roots of which are used medicinally. The storage roots of C. speciosa are derived from fibrous roots, but not all fibrous roots can develop into storage roots. To detect key genes involved in storage roots formation, we performed Illumina sequencing of the C. speciosa storage roots and fibrous roots. De novo assembly resulted in 161,926 unigenes, which were subsequently annotated by BLAST, GO and KEGG analyses. After expression profiling, 4538 differentially expressed genes were identified. The KEGG pathway enrichment analysis revealed changes in the biosynthesis of cytokinin, phenylpropanoid, starch, sucrose, flavone and other secondary metabolites. Transcription factor-related differentially expressed genes (DEGs) were also identified, including such gene families as GRAS, COL, MIKC, ERF, LBD, and NAC. The DEGs related to light signaling, starch, sugar, photohormones and cell wall-loosening might be involved in the formation of storage roots. This study provides the first transcriptome profiling of C. speciosa roots, data that will facilitate future research of root development and metabolites with medicinal value as well as the breeding of C. speciosa. PMID:27486800

  9. Les variations au champ de la biomasse microbienne d'un sol cultivé: conséquences sur la réserve organique mobilisable (cas d'un sol ferrugineux tropical au Sénégal)

    NASA Astrophysics Data System (ADS)

    Niane-Badianea, Aminata; Ganryb, Francis; Jacquinc, Fernand

    1999-01-01

    In an arenosol of the central part of northern Senegal, the microbial biomass expressed as mg C·kg -1 soil (BM-C) using the chloroform-fumigation incubation method was studied in two long term field trials respectively at Bambey and Thilmakha. BM-C expressed as percent of total soil organic C was higher than in temperate soils. The BM-C and the non-hydrolysable non-distillable nitrogen (Nhnd) were found to be correlated for both agrosystems. Agricultural activity (farmyard manuring and ploughing) did significantly increase these two parameters. The BM-C increased during the rainy season. This might be a key factor in the nitrogen flush at the onset of the rainy season in dry tropical areas, which is essential to the installation of the crop.

  10. Interfacial nanodroplets guided construction of hierarchical Au, Au-Pt, and Au-Pd particles as excellent catalysts

    PubMed Central

    Ma, Aijing; Xu, Jie; Zhang, Xuehua; Zhang, Bin; Wang, Dayang; Xu, Haolan

    2014-01-01

    Interfacial nanodroplets were grafted to the surfaces of self-sacrificed template particles in a galvanic reaction system to assist the construction of 3D Au porous structures. The interfacial nanodroplets were formed via direct adsorption of surfactant-free emulsions onto the particle surfaces. The interfacial nanodroplets discretely distributed at the template particle surfaces and served as soft templates to guide the formation of porous Au structures. The self-variation of footprint sizes of interfacial nanodroplets during Au growth gave rise to a hierarchical pore size distribution of the obtained Au porous particles. This strategy could be easily extended to synthesize bimetal porous particles such as Au-Pt and Au-Pd. The obtained porous Au, Au-Pt, and Au-Pd particles showed excellent catalytic activity in catalytic reduction of 4-nitrophenol. PMID:24797697

  11. The solar activity dependence of nonmigrating tides in electron density at low and middle latitudes observed by CHAMP and GRACE

    NASA Astrophysics Data System (ADS)

    Zhou, Yun-Liang; Wang, Li; Xiong, Chao; Lühr, Hermann; Ma, Shu-Ying

    2016-04-01

    In this paper we use more than a decade of in situ electron density observations from CHAMP and GRACE satellites to investigate the solar activity dependence of nonmigrating tides at both low and middle latitudes. The results indicate that the longitudinal patterns of F region electron density vary with season and latitude, which are exhibiting a wavenumber 4 (WN4) pattern around September equinox at low latitudes and WN1/WN2 patterns during local summer at the southern/northern middle latitudes. These wave patterns in the F region ionosphere can clearly be seen during both solar maximum and minimum years. At low latitudes the absolute amplitudes of DE3 (contributing to the WN4 pattern) are found to be highly related to the solar activity, showing larger amplitudes during solar maximum years. Similarly a solar activity dependence can also be found for the absolute amplitudes of D0, DW2 and DE1 (contributing to the WN1 and WN2 pattern) at middle latitudes. The relative amplitudes (normalized by the zonal mean) of these nonmigrating tides at both low and middle altitudes show little dependence on solar activity. We further found a clear modulation by the quasi-biennial oscillation (QBO) of the relative DE3 amplitudes in both satellite observations, which is consistent with the QBO dependence as reported for the E region temperatures and zonal wind. It also supports the strong coupling of the low-latitude nonmigrating tidal activity between the E and F regions. However, the QBO dependence cannot be found for the relative amplitudes of the nonmigrating tides at middle latitudes, which implies that these tides are generated in situ at F region altitudes.

  12. A statistical analysis of longitudinal dependences of upper thermospheric zonal winds at dip equator latitudes derived from CHAMP

    NASA Astrophysics Data System (ADS)

    Häusler, K.; Lühr, H.; Rentz, S.; Köhler, W.

    2007-08-01

    New observations, obtained by the accelerometer onboard the CHAMP satellite, reveal a detailed picture of the thermospheric zonal wind. Based on three years of data (2002 2004) we have studied the longitudinal dependence of the zonal delta wind (deviations from the zonal average) at the dip equator. The large number of passes (˜33 750) allows to consider several aspects of the wind characteristics at the same time. For this analysis we derived the longitudinal variation of the zonal delta wind at about 400 km altitude and investigated its dependence on solar flux, magnetic activity, and season. Major longitudinal dependences are confined to the morning hours, 03-09 local time (LT). The amplitude of the delta wind is approximately proportional to the latitudinal displacement of the magnetic dip equator from the geographic equator. The direction of the delta wind reverses sign between the June and December Solstices. During Equinox seasons these large scale features are almost absent. The flux level of solar EUV has no significant influence on the longitudinal variations. A dependence on magnetic activity could only be found during the post-sunset hours, 18-21 LT. Performing a Fourier transform of our delta wind velocities revealed a dominance of the wavenumber 4 in the Equinox data at some LT sectors. The wave-4 structure is a prevailing feature in the slowly precessing satellite frame, which has been recently reported, e.g. in nonmigrating tidal temperature measurements of the SABER instrument on the TIMED satellite in the Mesosphere Lower Thermosphere (MLT) region. Therefore, this statistical study of zonal wind longitudinal dependences provides new observational evidence for the coupling of the various atmospheric layers by nonmigrating tides.

  13. Multiscle Modelling of The Geomagnetic Field and Ionospheric Current Systems With Application To Champ Fgm-data

    NASA Astrophysics Data System (ADS)

    Mayer, C.; Maier, T.

    Based on the (quasi-)stationary Pre-Maxwell Equations, a multiscale method using spherical vectorial scaling functions and wavelets for the modelling of the geomag- netic field and ionospheric current systems will be presented. The theory of multiscale modelling of the geomagnetic field is essentially based on the Helmholtz represen- tation of spherical vector fields. The construction of respective scaling functions and wavelets allows separated analysis of the radial, the consoidal and the toroidal part of the geomagnetic field. The considerations about ionospheric current systems are essentially based on the Mie representation of solenoidal vector fields in terms of toroidal and poloidal parts. It will be shown how a vectorial wavelet representation of the geomagnetic field on a satel- lite's orbit can be used to determine a multiscale approximation of the radial as well as parts of the tangential current distribution at that height. This will be done by con- sidering the connection of the Mie representation of the geomagnetic field and the Mie representation of the current distribution, respectively, via the Beltrami differen- tial equation. The applicability and efficiency of the multiresolution techniques will be presented in both cases, the multiscale modelling of the geomagnetic field and the detection of current systems on a satellite's orbit. First results obtained from CHAMP FGM-data will be presented. In this context we want to pay special attention on the zoom-in property of our multiscale approach. Thus by using the space localizing properties of our scaling functions and wavelets, we are able to model the geomagnetic field and ionospheric current systems in a locally adaptive manner, i.e. by using only local data. References: [1 ] Bayer, M., Freeden W., Maier, T.: A Vector Wavelet Approach to Iono- and Magnetospheric Geomagnetic Satellite Data, Journal of Athmospheric and Solar-Terrestrial Physics 63, 581-597, 2001. [2 ] Maier, T.: Multiscale Analysis

  14. Upper Tropospheric and Stratospheric Radio Occultation Retrieval. A Validation Study Based on Data From CHAMP, ENVISAT Instruments, Radiosondes, and NWP Analyses

    NASA Astrophysics Data System (ADS)

    Gobiet, A.; Kirchengast, G.; Retscher, C.

    2003-12-01

    Current Global Navigation Satellite System (GNSS) radio occultation (RO) retrieval techniques generally yield excellent results on refractivity, geopotential height (or pressure), and temperature in the upper troposphere and lower stratosphere. Above 30 km, throughout the upper stratosphere, the errors of retrieved atmospheric profiles increase significantly. The retrievals can still be fairly accurate in the upper stratosphere, however, if one uses adequate high-altitude initialization and statistical optimization techniques invoking background data (e.g., from climatologies). Simulation studies showed that sensible use of independent background data has the ability to significantly reduce retrieval errors, especially biases, in the upper stratosphere (e.g., mean temperature biases < 0.25 1 K in the 30 to 40 km height domain). Results of these studies will be summarized. They make clear that, in particular, care is required not to introduce eventual biases from the background data into the retrieval results. In this study we focus on investigating the stratospheric RO retrieval performance, especially regarding temperature, when applying different high altitude initialization/statistical optimization schemes and different kinds of background information to CHAMP RO bending angle data. Atmospheric data products generated by the operational CHAMP processing system at GeoForschungsZentrum Potsdam (GFZ) and data products from the IGAM/CHAMP processing chain will be extensively validated with correlative data from ENVISAT instruments (MIPAS, GOMOS), radiosondes, and global NWP analyses (ECMWF analysis fields). Additionally, a new temperature product generated from the precise pointing data of the GOMOS steering front assembly will be introduced and used in the validation study. The validation results will be discussed with emphasis on the matter of upper stratospheric temperature biases in RO data.

  15. On the capability of Swarm for surface mass variation monitoring: Quantitative assessment based on orbit information from CHAMP, GRACE and GOCE

    NASA Astrophysics Data System (ADS)

    Baur, Oliver; Weigelt, Matthias; Zehentner, Norbert; Mayer-Gürr, Torsten; Jäggi, Adrian

    2014-05-01

    In the last decade, temporal variations of the gravity field from GRACE observations have become one of the most ubiquitous and valuable sources of information for geophysical and environmental studies. In the context of global climate change, mass balance of the Arctic and Antarctic ice sheets gained particular attention. Because GRACE has outlived its predicted lifetime by several years already, it is very likely that a gap between GRACE and its successor GRACE follow-on (supposed to be launched in 2017, at the earliest) occurs. The Swarm mission - launched on November 22, 2013 - is the most promising candidate to bridge this potential gap, i.e., to directly acquire large-scale mass variation information on the Earth's surface in case of a gap between the present GRACE and the upcoming GRACE follow-on projects. Although the magnetometry mission Swarm has not been designed for gravity field purposes, its three satellites have the characteristics for such an endeavor: (i) low, near-circular and near-polar orbits, (ii) precise positioning with high-quality GNSS receivers, (iii) on-board accelerometers to measure the influence of non-gravitational forces. Hence, from an orbit analysis point of view the Swarm satellites are comparable to the CHAMP, GRACE and GOCE spacecraft. Indeed and as data analysis from CHAMP has been shown, the detection of annual signals and trends from orbit analysis is possible for long-wavelength features of the gravity field, although the accuracy associated with the inter-satellite GRACE measurements cannot be reached. We assess the capability of the (non-dedicated) mission Swarm for mass variation detection in a real-case environment (opposed to simulation studies). For this purpose, we "approximate" the Swarm scenario by the GRACE+CHAMP and GRACE+GOCE constellations. In a first step, kinematic orbits of the individual satellites are derived from GNSS observations. From these orbits, we compute monthly combined GRACE+CHAMP and GRACE

  16. Au36(SPh)23 nanomolecules.

    PubMed

    Nimmala, Praneeth Reddy; Dass, Amala

    2011-06-22

    A new core size protected completely by an aromatic thiol, Au(36)(SPh)(23), is synthesized and characterized by MALDI-TOF mass spectrometry and UV-visible spectroscopy. The synthesis involving core size changes is studied by MS, and the complete ligand coverage by aromatic thiol group is shown by NMR.

  17. Global polarization measurement in Au+Au collisions

    SciTech Connect

    Abelev, B.I.; Adams, J.; Aggarwal, M.M.; Ahammed, Z.; Amonett,J.; Anderson, B.D.; Anderson, M.; Arkhipkin, D.; Averichev, G.S.; Bai,Y.; Balewski, J.; Barannikova, O.; Barnby, L.S.; Baudot, J.; Bekele, S.; Belaga, V.V.; Bellingeri-Laurikainen, A.; Bellwied, R.; Benedosso, F.; Bhardwaj, S.; Bhasin, A.; Bhati, A.K.; Bichsel, H.; Bielcik, J.; Bielcikova, J.; Bland, L.C.; Blyth, S.-L.; Bonner, B.E.; Botje, M.; Bouchet, J.; Brandin, A.V.; Bravar, A.; Bystersky, M.; Cadman, R.V.; Cai,X.Z.; Caines, H.; Calderon de la Barca Sanchez, M.; Castillo, J.; Catu,O.; Cebra, D.; Chajecki, Z.; Chaloupka, P.; Chattopadhyay, S.; Chen,H.F.; Chen, J.H.; Cheng, J.; Cherney, M.; Chikanian, A.; Christie, W.; Coffin, J.P.; Cormier, T.M.; Cosentino, M.R.; Cramer, J.G.; Crawford,H.J.; Das, D.; Das, S.; Daugherity, M.; de Moura, M.M.; Dedovich, T.G.; DePhillips, M.; Derevschikov, A.A.; Didenko, L.; Dietel, T.; Djawotho,P.; Dogra, S.M.; Dong, W.J.; Dong, X.; Draper, J.E.; Du, F.; Dunin, V.B.; Dunlop, J.C.; Dutta Mazumdar, M.R.; Eckardt, V.; Edwards, W.R.; Efimov,L.G.; Emelianov, V.; Engelage, J.; Eppley, G.; Erazmus, B.; Estienne, M.; Fachini, P.; Fatemi, R.; Fedorisin, J.; Filimonov, K.; Filip, P.; Finch,E.; Fine, V.; Fisyak, Y.; Fu, J.; Gagliardi, C.A.; Gaillard, L.; Ganti,M.S.; Ghazikhanian, V.; Ghosh, P.; Gonzalez, J.S.; Gorbunov, Y.G.; Gos,H.; Grebenyuk, O.; Grosnick, D.; Guertin, S.M.; Guimaraes, K.S.F.F.; Guo,Y.; Gupta, N.; Gutierrez, T.D.; Haag, B.; Hallman, T.J.; Hamed, A.; Harris, J.W.; He, W.; Heinz, M.; Henry, T.W.; Hepplemann, S.; Hippolyte,B.; Hirsch, A.; Hjort, E.; Hoffman, A.M.; Hoffmann, G.W.; Horner, M.J.; Huang, H.Z.; Huang, S.L.; Hughes, E.W.; Humanic, T.J.; Igo, G.; Jacobs,P.; Jacobs, W.W.; Jakl, P.; Jia, F.; Jiang, H.; Jones, P.G.; Judd, E.G.; Kabana, S.; Kang, K.; Kapitan, J.; Kaplan, M.; Keane, D.; Kechechyan, A.; Khodyrev,V.Yu.; Kim, B.C.; Kiryluk, J.; Kisiel, A.; Kislov, E.M.; Klein,S.R.; Kocoloski, A.; Koetke, D.D.; et al.

    2007-08-02

    The system created in non-central relativisticnucleus-nucleus collisions possesses large orbital angular momentum. Dueto spin-orbit coupling, particles produced in such a system could becomeglobally polarized along the direction of the system angular momentum. Wepresent the results of Lambda and anti-Lambda hyperon global polarizationmeasurements in Au+Au collisions at sqrt sNN=62.4 GeV and 200 GeVperformed with the STAR detector at RHIC. The observed globalpolarization of Lambda and anti-Lambda hyperons in the STAR acceptance isconsistent with zero within the precision of the measurements. Theobtained upper limit, lbar P Lambda, anti-Lambda rbar<= 0.02, iscompared to the theoretical values discussed recently in theliterature.

  18. CM5, a Pre-Swarm Comprehensive Geomagnetic Field Model Derived from Over 12 Yr of CHAMP, Orsted, SAC-C and Observatory Data

    NASA Technical Reports Server (NTRS)

    Sabaka, Terence J.; Olsen, Nils; Tyler, Robert H.; Kuvshinov, Alexey

    2014-01-01

    A comprehensive magnetic field model named CM5 has been derived from CHAMP, Ørsted and SAC-C satellite and observatory hourly-means data from 2000 August to 2013 January using the Swarm Level-2 Comprehensive Inversion (CI) algorithm. Swarm is a recently launched constellation of three satellites to map the Earth's magnetic field. The CI technique includes several interesting features such as the bias mitigation scheme known as Selective Infinite Variance Weighting (SIVW), a new treatment for attitude error in satellite vector measurements, and the inclusion of 3-D conductivity for ionospheric induction. SIVW has allowed for a much improved lithospheric field recovery over CM4 by exploiting CHAMP along-track difference data yielding resolution levels up to spherical harmonic degree 107, and has allowed for the successful extraction of the oceanic M2 tidal magnetic field from quiet, nightside data. The 3-D induction now captures anomalous Solar-quiet features in coastal observatory daily records. CM5 provides a satisfactory, continuous description of the major magnetic fields in the near-Earth region over this time span, and its lithospheric, ionospheric and oceanic M2 tidal constituents may be used as validation tools for future Swarm Level-2 products coming from the CI algorithm and other dedicated product algorithms.

  19. PROBING THE BALANCE OF AGN AND STAR-FORMING ACTIVITY IN THE LOCAL UNIVERSE WITH ChaMP

    SciTech Connect

    Constantin, Anca; Green, Paul; Aldcroft, Tom; Kim, Dong-Woo; Haggard, Daryl; Anderson, Scott F.; Barkhouse, Wayne

    2009-11-10

    The combination of the Sloan Digital Sky Survey (SDSS) and the Chandra Multiwavelength Project (ChaMP) currently offers the largest and most homogeneously selected sample of nearby galaxies for investigating the relation between X-ray nuclear emission, nebular line emission, black hole masses, and properties of the associated stellar populations. We provide X-ray spectral fits and valid uncertainties for all the galaxies with counts ranging from 2 to 1325 (mean 76, median 19). We present here novel constraints that both X-ray luminosity L{sub X} and X-ray spectral energy distribution bring to the galaxy evolutionary sequence H II -> Seyfert/Transition Object -> LINER -> Passive suggested by optical data. In particular, we show that both L{sub X} and GAMMA, the slope of the power law that best fits the 0.5-8 keV spectra, are consistent with a clear decline in the accretion power along the sequence, corresponding to a softening of their spectra. This implies that, at z approx 0, or at low-luminosity active galactic nucleus (AGN) levels, there is an anticorrelation between GAMMA and L/L {sub edd}, opposite to the trend exhibited by high z AGN (quasars). The turning point in the GAMMA-L/L{sub edd} LLAGN + quasars relation occurs near GAMMA approx 1.5 and L/L{sub edd} approx 0.01. Interestingly, this is identical to what stellar mass X-ray binaries exhibit, indicating that we have probably found the first empirical evidence for an intrinsic switch in the accretion mode, from advection-dominated flows to standard (disk/corona) accretion modes in supermassive black hole accretors, similar to what has been seen and proposed to happen in stellar mass black hole systems. The anticorrelation we find between GAMMA and L/L{sub edd} may instead indicate that stronger accretion correlates with greater absorption. Therefore, the trend for softer spectra toward more luminous, high redshift, and strongly accreting (L/L{sub edd} approx> 0.01) AGNs/quasars could simply be the result

  20. Ionosphere modeling by means of electron density profiles based on the satellite missions COSMIC, CHAMP and GRACE.

    NASA Astrophysics Data System (ADS)

    Limberger, Marco; Hugentobler, Urs; Schmidt, Michael; Dettmering, Denise; Liang, Wenjing; Jakowski, Norbert; Hoque, Mainul; Gerzen, Tatjana; Berdermann, Jens

    2013-04-01

    contribution, the focus is on the consideration of electron density profiles to estimate the B-spline series coefficients which allow for the reconstruction of the key parameters and eventually improve the initial model. Data of three LEO satellite missions, in particular the "Constellation Observing System for Meterorology, Ionosphere and Climate" (COSMIC), "CHAllenging Minisatellite Payload" (CHAMP) and "Gravity Recovery And Climate Experiment" (GRACE) are taken into account. Contact: marco.limberger@bv.tum.de

  1. d + Au hadron correlation measurements at PHENIX

    SciTech Connect

    Anne M. Sickles

    2014-05-13

    In these proceedings, we discuss recent results from d + Au collisions in PHENIX ridge related measurements and their possible hydrodynamic origin. We present the v2 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 v2 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. Synthesis and optical property characterization of elongated AuPt and Pt@Au metal nanoframes

    NASA Astrophysics Data System (ADS)

    Lee, Sangji; Jang, Hee-Jeong; Jang, Ho Young; Hong, Soonchang; Moh, Sang Hyun; Park, Sungho

    2016-02-01

    We report a facile method to synthesize elongated nanoframes consisting of Pt and Au in solution. Pentagonal Au nanorods served as templates and successfully led to an elongated AuPt nanoframe after etching the core Au. Subsequently, the coating of Au around Pt ridges resulted in Pt@Au metal nanoframes. The resulting elongated nanostructure exhibited 5 well-defined ridges continuously connected along the long axis. During the shape evolution from pure Au nanorods to elongated Pt@Au metal nanoframes, their corresponding localized surface plasmon resonance bands were monitored. Especially, unique surface plasmon features were observed for elongated Pt@Au nanoframes where the short-axis oscillation of surface free electrons is strongly coupled but the long-axis oscillation is not coupled among the ridges.We report a facile method to synthesize elongated nanoframes consisting of Pt and Au in solution. Pentagonal Au nanorods served as templates and successfully led to an elongated AuPt nanoframe after etching the core Au. Subsequently, the coating of Au around Pt ridges resulted in Pt@Au metal nanoframes. The resulting elongated nanostructure exhibited 5 well-defined ridges continuously connected along the long axis. During the shape evolution from pure Au nanorods to elongated Pt@Au metal nanoframes, their corresponding localized surface plasmon resonance bands were monitored. Especially, unique surface plasmon features were observed for elongated Pt@Au nanoframes where the short-axis oscillation of surface free electrons is strongly coupled but the long-axis oscillation is not coupled among the ridges. Electronic supplementary information (ESI) available. See DOI: 10.1039/c5nr08200e

  3. Teach Like a Champ

    ERIC Educational Resources Information Center

    Adams, Caralee

    2011-01-01

    Doug Lemov didn't set out to write a book about the tools of the teaching craft. Working as a managing director of a group of urban charter public schools, he was just trying to get some answers for his teachers. They were hungry for tips on how to really engage kids and solve problems that were getting in the way of their teaching. Lemov observed…

  4. Interpretation of the Total Magnetic Field Anomalies Measured by the CHAMP Satellite Over a Part of Europe and the Pannonian Basin

    NASA Technical Reports Server (NTRS)

    Kis, K. I.; Taylor, Patrick T.; Wittmann, G.; Toronyi, B.; Puszta, S.

    2012-01-01

    In this study we interpret the magnetic anomalies at satellite altitude over a part of Europe and the Pannonian Basin. These anomalies are derived from the total magnetic measurements from the CHAMP satellite. The anomalies reduced to an elevation of 324 km. An inversion method is used to interpret the total magnetic anomalies over the Pannonian Basin. A three dimensional triangular model is used in the inversion. Two parameter distributions: Laplacian and Gaussian are investigated. The regularized inversion is numerically calculated with the Simplex and Simulated Annealing methods and the anomalous source is located in the upper crust. A probable source of the magnetization is due to the exsolution of the hematite-ilmenite minerals.

  5. The magic gold cluster Au20

    NASA Astrophysics Data System (ADS)

    Kryachko, E. S.; Remacle, F.

    The 20-nanogold cluster Au20 exhibits a large variety of two- and three-dimensional isomeric forms. Among them is the ground-state isomer Au20(Td) representing the stable cluster with a unique tetrahedral shape, with all atoms on the surface, and large HOMO-LUMO gap which even slightly exceeds that of the buckyball fullerene C60. The anionic cluster Au-20(Td) that holds its parent tetrahedral symmetry features a high catalytic activity. The list of the properties of the 20-nanogold clusters surveyed in the present work ranges from the energetic order of stability of its isomers to the optical absorption and excitation spectra of the Au20(Td) cluster. We also report the structures and properties of its doubly charged clusters Au2+20 and Au2-20 and computationally confirm that Au2-20 is indeed stable. The zero-point-energy-corrected adiabatic second electron affinity of Au20(Td) amounts to 0.43-0.53 eV that is consistent with the experimental data. In addition, we provide computational evidence of the existence of the novel, hollow cage isomer of Au20 and analyze its key properties.0

  6. CHAMP, SWARM, and WDMAM magnetic data; three reasons for further developing techniques for modeling the lithospheric magnetic field at regional scales

    NASA Astrophysics Data System (ADS)

    Thebault, E.; Vervelidou, F.

    2012-04-01

    The spatial resolution of all available data monitoring the Earth's lithospheric magnetic field range from thousands to few kilometers at the regional spatial scale. The data type and measurement platforms covering these various wavelengths are in general different. For instance, Low Earth Orbiting satellites, such as CHAMP and the forthcoming SWARM, measure the vector field and are sensitive to large-scale and deep lithospheric magnetic field structures, while aeromagnetic and marine data or grids, like the World Digital Magnetic Anomaly Map (WDMAM), which are mostly scalar, in general fetch better shallow and small spatial scale signals. For quantitative geophysical interpretations, there is therefore a need for methodologies allowing for the reconstruction of the full magnetic field spectrum. During the last decades, various methodologies have been proposed in an effort to merge all kinds of magnetic data available over particular regions. We first briefly review the methods proposed by the scientific community and will more specifically focus on new progresses in developing the Revised Spherical Cap modeling approach. In particular, we will discuss the concept of spectrum with this formalism and its applicability in the framework of geomagnetism. Since a regional modeling approach can only be applied on high quality data we then propose some strategies to first obtain a better signal to noise ratio in satellite data and second to better account for its nature. We will illustrate our conclusions with issues faced with the data processing of single satellite missions such as CHAMP. Finally, we discuss how a constellation such as the Swarm mission will alleviate some of, so far, unresolved problems and how important it is to have the metadata information about the aeromagnetic and marine anomaly data.

  7. Synthesis and Optical Responses of Ag@Au/Ag@Au Double Shells

    NASA Astrophysics Data System (ADS)

    Li, Ying-Ying; Liu, Xiao-Li; Yang, Da-Jie; Hao, Zhong-Hua; Wang, Qu-Quan

    2015-02-01

    We synthesize hollow-structured Ag@Au nanoparticles with single porous shell and Ag@Au/Ag@Au double shells by using the galvanic replacement reaction and investigate their linear and nonlinear optical properties. Our results show that the surface plasmon resonance wavelength of the hollow porous nanoparticles could be easily tuned in a wide range in the visible and near infrared region by controlling the volume of HAuCl4. The nonlinear optical refraction of the double-shelled Ag@Au/Ag@Au nanoparticles is prominently enhanced by the plasmon resonance. Our findings may find applications in biosensors and nonlinear optical nanodevices.

  8. Au microstructure and the functional properties of Ni/Au finishes on ceramic IC packages

    SciTech Connect

    Winters, E.D.; Baxter, W.K.; Braski, D.N.; Watkins, T.R.

    1995-12-31

    Ni/Au plated finishes used on thick-film metallized multilayer ceramic packages for integrated circuits must meet functional requirements such as bondability, sealability, and solderability. Their ability to do so is dependent, among other things, on the ability of the Au deposit to inhibit the grain boundary diffusion and subsequent surface oxidation of Ni. In this study, the relation between functional performance, Ni diffusionr ate, and Au microstructure was examined. Extent of Ni diffusion during heating was determined by Auger electron spectroscopy for several electrolytic and electroless Ni/Au finishing processes. Results were correlated with differences in Au microstructures determined by SEM, atomic force microscopy, and XRD.

  9. Electrochemical formation of Au clusters in polyaniline

    SciTech Connect

    Hatchett, D.W.; Josowicz, M.; Janata, J.; Baer, D.R.

    1999-10-01

    The reduction of chloroaurate and the incorporation of Au clusters in polyaniline, PANI, films have been investigated. The chloroaurate complex is generated at the electrode surface during Cl{sup {minus}} doping of Au/PANI. FTIE and UV/vis data indicate that chloroaurate interacts with PANI and that its reduction to metallic Au occurs preferentially at the nitrogen linkages. The voltammetric and XPS results show that the uptake of both protons and anions is suppressed by the formation of Au clusters due to this interaction. The ability to reduce chloroaurate in PANI films is also demonstrated for Pt electrodes coated with PANI in solutions containing KAuCl{sub 4}. The preliminary results indicate that Au cluster size distribution remains fairly constant regardless of the method used.

  10. Polyethylene terephthalate (PET) bulk film analysis using C 60+, Au 3+, and Au + primary ion beams

    NASA Astrophysics Data System (ADS)

    Conlan, X. A.; Gilmore, I. S.; Henderson, A.; Lockyer, N. P.; Vickerman, J. C.

    2006-07-01

    The damage characteristics of polyethylene terephthalate (PET) have been studied under bombardment by C 60+, Au 3+ and Au + primary ions. The observed damage cross-sections for the three ion beams are not dramatically different. The secondary ion yields however were significantly enhanced by the polyatomic primary ions where the secondary ion yield of the [M + H] + is on average 5× higher for C 60+ than Au 3+ and 8× higher for Au 3+ than Au +. Damage accumulates under Au + and Au 3+ bombardment while C 60+ bombardment shows a lack of damage accumulation throughout the depth profile of the PET thick film up to an ion dose of ˜1 × 10 15 ions cm -2. These properties of C 60+ bombardment suggest that the primary ion will be a useful molecular depth profiling tool.

  11. Investigation of the Phase Equilibria of Sn-Cu-Au Ternary and Ag-Sn-Cu-Au Quaternary Systems and Interfacial Reactions in Sn-Cu/Au Couples

    NASA Astrophysics Data System (ADS)

    Yen, Yee-Wen; Jao, Chien-Chung; Hsiao, Hsien-Ming; Lin, Chung-Yung; Lee, Chiapyng

    2007-02-01

    The phase equilibria of the Sn-Cu-Au ternary, Ag-Sn-Cu-Au quaternary systems and interfacial reactions between Sn-Cu alloys and Au were experimentally investigated at specific temperatures in this study. The experimental results indicated that there existed three ternary intermetallic compounds (IMCs) and a complete solid solubility between AuSn and Cu6Sn5 phases in the Sn-Cu-Au ternary system at 200°C. No quaternary IMC was found in the isoplethal section of the Ag-Sn-Cu-Au quaternary system. Three IMCs, AuSn, AuSn2, and AuSn4, were found in all couples. The same three IMCs and (Au,Cu)Sn/(Cu,Au)6Sn5 phases were found in all Sn-Cu/Au couples. The thickness of these reaction layers increased with increasing temperature and time. The mechanism of IMC growth can be described by using the parabolic law. In addition, when the reaction time was extended and the Cu content of the alloy was increased, the AuSn4 phase disappeared gradually. The (Au, Cu)Sn and (Cu,Au)6Sn5 layers played roles as diffusion barriers against Sn in Sn-Cu/Au reaction couple systems.

  12. Thermal and photoinduced reduction of ionic Au(III) to elemental Au nanoparticles by dissolved organic matter in water: possible source of naturally occurring Au nanoparticles.

    PubMed

    Yin, Yongguang; Yu, Sujuan; Liu, Jingfu; Jiang, Guibin

    2014-01-01

    Naturally occurring Au nanoparticles (AuNPs) have been widely observed in ore deposits, coal, soil, and environmental water. Identifying the source of these naturally occurring AuNPs could be helpful for not only the discovery of Au deposits through advanced exploration methods, but also the elucidation of the biogeochemical cycle and environmental toxicity of ionic Au and engineered AuNPs. Here, we investigated the effect of natural/simulated sunlight and heating on the reduction of ionic Au by ubiquitous dissolved organic matter (DOM) in river water. The reductive process probed by X-ray photoelectron spectroscopy revealed that phenolic, alcoholic, and aldehyde groups in DOM act as reductive sites. Long-time exposure with thermal and photoirradiation induced the further fusion and growth of AuNPs to branched Au nanostructure as precipitation. The formation processes and kinetics of AuNPs were further investigated using humic acid (HA) as the DOM model, with comprehensive characterizing methods. We have observed that HA can reduce ionic Au(III) complex (as chloride or hydroxyl complex) to elemental Au nanoparticles under sunlight or heating. In this process, nearly all of the Au(III) could be reduced to AuNPs, in which HA serves as not only the reductive agent, but also the coating agent to stabilize and disperse AuNPs. The size and stability of AuNPs were highly dependent on the concentration ratio of Au(III) to HA. These results imply that, besides biological processes, this thermal or photochemical reduction process is another possible source of naturally occurring AuNPs in natural environments, which possibly has critical impacts on the transport and transformation of Au and engineered AuNPs.

  13. On the influence of the ground track on the gravity field recovery from high-low satellite-to-satellite tracking missions: CHAMP monthly gravity field recovery using the energy balance approach revisited

    NASA Astrophysics Data System (ADS)

    Weigelt, Matthias; Sideris, Michael G.; Sneeuw, Nico

    2009-12-01

    In this paper, the influence of the ground track coverage on the quality of a monthly gravity field solution is investigated for the scenario of a high-low satellite- to-satellite tracking mission. Data from the CHAllenging Minisatellite Payload ( champ) mission collected in the period April 2002 to February 2004 has been used to recover the gravity field to degree and order 70 on a monthly basis. The quality is primarily restricted by the accuracy of the instruments. Besides, champ passed through a 31/2 repeat mode three times during the period of interest resulting in an insufficient spatial sampling and a degraded solution. Contrary to the rule of thumb by Colombo (The global mapping of gravity with two satellites, Publications on Geodesy, vol 7(3), Netherlands Geodetic Commission, The Netherlands, 263 pp, 1984), see also Wagner (J Geod 80(2): 94-103, 2006), we found that the monthly solutions themselves could be recovered to about degree 30, not 15. In order to improve the monthly gravity solutions, two strategies have been developed: the restriction to a low degree, and the densification of the sampling by the introduction of additional sensitive measurements from contemporaneous satellite missions. The latter method is tested by combining the champ measurements with data from the Gravity Recovery And Climate Experiment ( grace). Note that the two grace satellites are considered independent here, i.e. no use is made of the K-band ranging data. This way, we are able to almost entirely remove the influence of the ground track leaving the accuracy of the instruments as the primary restriction on the quality of a monthly solution. These findings are especially interesting for the upcoming swarm-mission since it will consist of a similar configuration as the combined champ and ( grace) missions.

  14. Self-assembly of thiolated cyanine aggregates on Au(111) and Au nanoparticle surfaces

    NASA Astrophysics Data System (ADS)

    Menéndez, Guillermo O.; Cortés, Emiliano; Grumelli, Doris; Méndez de Leo, Lucila P.; Williams, Federico J.; Tognalli, Nicolás G.; Fainstein, Alejandro; Vela, María Elena; Jares-Erijman, Elizabeth A.; Salvarezza, Roberto C.

    2012-01-01

    Heptamethinecyanine J-aggregates display sharp, intense fluorescence emission making them attractive candidates for developing a variety of chem-bio-sensing applications. They have been immobilized on planar thiol-covered Au surfaces and thiol-capped Au nanoparticles by weak molecular interactions. In this work the self-assembly of novel thiolated cyanine (CNN) on Au(111) and citrate-capped AuNPs from solutions containing monomers and J-aggregates has been studied by using STM, XPS, PM-IRRAS, electrochemical techniques and Raman spectroscopy. Data show that CNN species adsorb on the Au surfaces by forming thiolate-Au bonds. We found that the J-aggregates are preferentially adsorbed on the Au(111) surface directly from the solution while adsorbed CNN monomers cannot organize into aggregates on the substrate surface. These results indicate that the CNN-Au interaction is not able to disorganize the large J-aggregates stabilized by π-π stacking to optimize the S-Au binding site but it is strong enough to hinder the π-π stacking when CNNs are chemisorbed as monomers. The optical properties of the J-aggregates remain active after adsorption. The possibility of covalently bonding CNN J-aggregates to Au planar surfaces and Au nanoparticles controlling the J-aggregate/Au distance opens a new path regarding their improved stability and the wide range of biological applications of both CNN and AuNP biocompatible systems.Heptamethinecyanine J-aggregates display sharp, intense fluorescence emission making them attractive candidates for developing a variety of chem-bio-sensing applications. They have been immobilized on planar thiol-covered Au surfaces and thiol-capped Au nanoparticles by weak molecular interactions. In this work the self-assembly of novel thiolated cyanine (CNN) on Au(111) and citrate-capped AuNPs from solutions containing monomers and J-aggregates has been studied by using STM, XPS, PM-IRRAS, electrochemical techniques and Raman spectroscopy. Data show

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

    PubMed

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

    2016-08-01

    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. PMID:27385583

  16. Au40: A Large Tetrahedral Magic Cluster

    SciTech Connect

    Jiang, Deen; Walter, Michael

    2011-01-01

    40 is a magic number for tetrahedral symmetry predicted in both nuclear physics and the electronic jellium model. We show that Au{sub 40} could be such a magic cluster from density functional theory-based basin hopping for global minimization. The putative global minimum found for Au{sub 40} has a twisted pyramid structure, reminiscent of the famous tetrahedral Au{sub 20}, and a sizable HOMO-LUMO gap of 0.69 eV, indicating its molecular nature. Analysis of the electronic states reveals that the gap is related to shell closings of the metallic electrons in a tetrahedrally distorted effective potential.

  17. Ir-induced activation of Au towards CO adsorption: Ir films deposited on Au{111}

    NASA Astrophysics Data System (ADS)

    Zhang, Tianfu; Driver, Stephen M.; Pratt, Stephanie J.; Jenkins, Stephen J.; King, David A.

    2016-06-01

    We have investigated the interaction of CO with Ir/Au{111} bimetallic surfaces, and the influence of morphology changes as Ir moves sub-surface into the Au bulk, using reflection-absorption infrared spectroscopy (RAIRS). The presence of Ir stabilises CO on exposed regions of the Au surface at temperatures up to around 200 K: we attribute this to low-coordinated Au sites, probably associated with lifting of the clean-surface 'herringbone' reconstruction by Ir deposition. The highest density of active Au sites is obtained after annealing the bimetallic surface to 500-600 K: we attribute this to morphology changes associated with the movement of Ir into bulk Au.

  18. Longitudinal scaling of net-protons in AuAu and pp collisions at RHIC energies

    NASA Astrophysics Data System (ADS)

    Videbaek, Flemming

    2008-10-01

    BRAHMS has studied net-protons distributions in Au+Au and p+p collisions at √sNN=62.4 and 200 GeV. Net-proton distributions reflect the net-baryon yields and can be used to extract the nuclear stopping in the collisions, thus providing information on baryon number transport and energy available for particle production. The talk will present final and preliminary results from the above mentioned systems. It will be shown that in p+p and in Au+Au central collisions that net-proton distributions exhibit longitudinal scaling once the target contribution to the projectile rapidity range is corrected for. The difference between p+p and Au+Au will be discussed. Aspects of future measurements at the LHC of net-baryons at mid-rapidity will be brought forth.

  19. Thermal Expansion of AuIn2

    SciTech Connect

    Saw, C K; Siekhaus, W J

    2004-07-12

    The thermal expansion of AuIn{sub 2} gold is of great interest in soldering technology. Indium containing solders have been used to make gold wire interconnects at low soldering temperature and over time, AuIn{sub 2} is formed between the gold wire and the solder due to the high heat of formation and the high inter-metallic diffusion of indium. Hence, the thermal expansion of AuIn{sub 2} alloy in comparison with that of the gold wire and the indium-containing solder is critical in determining the integrity of the connection. We present the results of x-ray diffraction measurement of the coefficient of linear expansion of AuIn{sub 2} as well as the bulk expansion and density changes over the temperature range of 30 to 500 C.

  20. RHIC Au beam in Run 2014

    SciTech Connect

    Zhang, S. Y.

    2014-09-15

    Au beam at the RHIC ramp in run 2014 is reviewed together with the run 2011 and run 2012. Observed bunch length and longitudinal emittance are compared with the IBS simulations. The IBS growth rate of the longitudinal emittance in run 2014 is similar to run 2011, and both are larger than run 2012. This is explained by the large transverse emittance at high intensity observed in run 2012, but not in run 2014. The big improvement of the AGS ramping in run 2014 might be related to this change. The importance of the injector intensity improvement in run 2014 is emphasized, which gives rise to the initial luminosity improvement of 50% in run 2014, compared with the previous Au-Au run 2011. In addition, a modified IBS model, which is calibrated using the RHIC Au runs from 9.8 GeV/n to 100 GeV/n, is presented and used in the study.

  1. Molecular dynamics simulation of energetic atom depositions of Au/Au(100) film

    NASA Astrophysics Data System (ADS)

    Qing-yu, Zhang; Zheng-ying, Pan; Jia-yong, Tang

    1999-04-01

    The energetic atom deposition of thin Au/Au(100) film has been studied by molecular dynamics simulation using the Au-Au interatomic interaction potential with embedded atom method. By investigating the variation of coverage curves and Bragg diffraction intensities during the film growth, the transition of Stranski-Kranstanov growth mode to Frank-van der Merwe growth mode was observed with the increase of the incident energy of deposition atoms. The role of energetic atoms in the film growth is discussed by analyzing the transport properties of deposited atoms and the evolution of incident energy and substrate temperatures.

  2. Unravelling Thiol's Role in Directing Asymmetric Growth of Au Nanorod-Au Nanoparticle Dimers.

    PubMed

    Huang, Jianfeng; Zhu, Yihan; Liu, Changxu; Shi, Zhan; Fratalocchi, Andrea; Han, Yu

    2016-01-13

    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.

  3. Counterion-Mediated Assembly of Spherical Nucleic Acid-Au Nanoparticle Conjugates (SNA-AuNPs)

    NASA Astrophysics Data System (ADS)

    Kewalramani, Sumit; Moreau, Liane; Guerrero-García, Guillermo; Mirkin, Chad; Olvera de La Cruz, Monica; Bedzyk, Michael; Afosr Muri Team

    2015-03-01

    Controlled crystallization of colloids from solution has been a goal of material scientists for decades. Recently, nucleic acid functionalized spherical Au nanoparticles (SNA-AuNPs) have been programmed to assemble in a wide variety of crystal structures. In this approach, the assembly is driven by Watson-Crick hybridization between DNAs coating the AuNPs. Here, we show that counterions can induce ordered assembly of SNA-AuNPs in bulk solutions, even in the absence of base pairing interactions. The electrostatics-driven assembly of spherical nucleic acid-Au nanoparticle conjugates (SNA-AuNPs) is probed as a function of counterion concentration and counterion valency [ +1 (Na+) or +2 (Ca2+) ] by in situ solution X-ray scattering. Assemblies of AuNPs capped with single-stranded (ss-) or double-stranded (ds-) DNA are examined. SAXS reveals disordered (gas-like) --> face-centered-cubic (FCC) --> glass-like phase transitions with increasing solution ionic strength. These studies demonstrate how non-base-pairing interactions can be tuned to create crystalline assemblies of SNA-AuNPs. The dependence of the inter-SNA-AuNP interactions on counterion valency and stiffness of the DNA corona will be discussed.

  4. Kinetics of Phase Transformations in CuAu Alloys

    NASA Astrophysics Data System (ADS)

    Malis, O.; Ludwig, K.

    1997-03-01

    We have performed time resolved x-ray scattering studies of the kinetics of phase transformations in CuAu alloys. The equilibrium phase diagram of CuAu presents two first-order ordering transitions which separate the stability range of a high temperature disordered phase and two ordered phases: CuAuI and CuAuII. CuAuII is a modulated phase having a wavelength ten times larger than CuAuI. Our study focused on the competition between CuAuI and CuAuII as well as on the interaction between order and strain as the lattice changes from cubic in the disordered phase to tetragonal in CuAuI. During CuAuI formation from the disordered phase, CuAuII appears and persists even for quenches deep below the coexistence point of CuAuI and CuAuII. We have also found that the formation of CuAuI from CuAuII is considerably slower than the formation of CuAuI from the disordered phase for equal quench temperatures. Langevin simulations based on EMT are in good qualitative agreement with the x-ray results(Elder, Malis, Ludwig, Chakraborty, Goldenfeld in preparation.). With increasing quench depth we also observe a change in kinetics from an incoherent nucleation process to a continuous transformation of the lattice while ordering.

  5. Systematic Measurements of Identified Particle Spectra in pp, d+Au and Au+Au Collisions from STAR

    SciTech Connect

    STAR Coll

    2009-04-11

    Identified charged particle spectra of {pi}{sup {+-}}, K{sup {+-}}, p and {bar p} at mid-rapidity (|y| < 0.1) measured by the dE/dx method in the STAR-TPC are reported for pp and d + Au collisions at {radical}s{sub NN} = 200 GeV and for Au + Au collisions at 62.4 GeV, 130 GeV, and 200 GeV. Average transverse momenta, total particle production, particle yield ratios, strangeness and baryon production rates are investigated as a function of the collision system and centrality. The transverse momentum spectra are found to be flatter for heavy particles than for light particles in all collision systems; the effect is more prominent for more central collisions. The extracted average transverse momentum of each particle species follows a trend determined by the total charged particle multiplicity density. The Bjorken energy density estimate is at least several GeV/fm{sub 3} for a formation time less than 1 fm/c. A significantly larger net-baryon density and a stronger increase of the net-baryon density with centrality are found in Au + Au collisions at 62.4 GeV than at the two higher energies. Antibaryon production relative to total particle multiplicity is found to be constant over centrality, but increases with the collision energy. Strangeness production relative to total particle multiplicity is similar at the three measured RHIC energies. Relative strangeness production increases quickly with centrality in peripheral Au + Au collisions, to a value about 50% above the pp value, and remains rather constant in more central collisions. Bulk freeze-out properties are extracted from thermal equilibrium model and hydrodynamics-motivated blast-wave model fits to the data. Resonance decays are found to have little effect on the extracted kinetic freeze-out parameters due to the transverse momentum range of our measurements. The extracted chemical freeze-out temperature is constant, independent of collision system or centrality; its value is close to the predicted phase

  6. [The pure being of writing. Ecriture automatique in 19th century psychiatry and early surrealism (Breton/Soupault: Les champs magnétiques)].

    PubMed

    Bergengruen, Maximilian

    2009-03-01

    Ecriture automatique and psychoanalysis are often lumped together in literary studies, almost as a knee-jerk reaction. However, on closer inspection it can be seen that the discoverers of automatic writing--the surrealists--were more interested in the hysteria research that prevailed around the year 1900 (Pierre Janet, Alfred Binet) and in parapsychology (Frederic Myers). In these two branches of medicine, the theory and practice of automatic writing are based on an experimental constellation in which the relationship between the psychiatrist/experiment organiser and the patient/participant takes centre stage. Here, the latter writes in response to an order or question from the former, mostly while overcoming a physical or memory block. André Breton and Philippe Soupault set up a very similar constellation in the Champs magnétiques, though with some key alterations. Indeed, surrealism liberates the patient engaging in automatic writing from the dictates of the psychiatrist--but only to submit him to a yet more overwhelming force, a pure violence of writing, so to speak: the automatism of a 'higher reality'.

  7. [The pure being of writing. Ecriture automatique in 19th century psychiatry and early surrealism (Breton/Soupault: Les champs magnétiques)].

    PubMed

    Bergengruen, Maximilian

    2009-03-01

    Ecriture automatique and psychoanalysis are often lumped together in literary studies, almost as a knee-jerk reaction. However, on closer inspection it can be seen that the discoverers of automatic writing--the surrealists--were more interested in the hysteria research that prevailed around the year 1900 (Pierre Janet, Alfred Binet) and in parapsychology (Frederic Myers). In these two branches of medicine, the theory and practice of automatic writing are based on an experimental constellation in which the relationship between the psychiatrist/experiment organiser and the patient/participant takes centre stage. Here, the latter writes in response to an order or question from the former, mostly while overcoming a physical or memory block. André Breton and Philippe Soupault set up a very similar constellation in the Champs magnétiques, though with some key alterations. Indeed, surrealism liberates the patient engaging in automatic writing from the dictates of the psychiatrist--but only to submit him to a yet more overwhelming force, a pure violence of writing, so to speak: the automatism of a 'higher reality'. PMID:19824309

  8. The influence of anthropometry and body composition on children's bone health: the childhood health, activity and motor performance school (the CHAMPS) study, Denmark.

    PubMed

    Heidemann, Malene; Holst, René; Schou, Anders J; Klakk, Heidi; Husby, Steffen; Wedderkopp, Niels; Mølgaard, Christian

    2015-02-01

    Overweight, physical inactivity and sedentary behaviour have become increasing problems during the past decade. Increased sedentary behaviour may change the body composition (BC) by increasing the fat mass relative to the lean mass (LM). These changes may influence bone health to describe how anthropometry and BC predict the development of the bone accruement. The longitudinal study is a part of The CHAMPS study-DK. Children were DXA scanned at baseline and at 2-year follow-up. BC (LM, BF %) and BMC, BMD and BA were measured. The relationship between bone traits, anthropometry and BC was analysed by multilevel regression analyses. Of the invited children, 742/800 (93%) accepted to participate. Of these, 682/742 (92%) participated at follow-up. Mean (range) of age at baseline was 9.5 years (7.7-12.1). Height, BMI, LM and BF % predicted bone mineral accrual and bone size positively and independently. Height and BMI are both positive predictors of bone accruement. LM is a more precise predictor of bone traits than BF % in both genders. The effects of height and BMI and LM on bone accruement are nearly identical in the two genders, while changes in BF % have different but positive effects on bone accretion in both boys and girls.

  9. Upper Atmospheric Response to the April 2010 Storm as Observed by GOCE, CHAMP, and GRACE and Modeled by TIME-GCM

    NASA Astrophysics Data System (ADS)

    Hagan, Maura; Häusler, Kathrin; Lu, Gang; Forbes, Jeffrey; Zhang, Xiaoli; Doornbos, Eelco; Bruinsma, Sean

    2014-05-01

    We present the results of an investigation of the upper atmosphere during April 2010 when it was disturbed by a fast-moving coronal mass ejection. Our study is based on comparative analysis of observations made by the Gravity field and steady-state Ocean Circulation Explorer (GOCE), Challenging Minisatellite Payload (CHAMP), and Gravity Recovery And Climate Experiment (GRACE) satellites and a set of simulations with the National Center for Atmospheric Research (NCAR) thermosphere-ionosphere-mesosphere-electrodynamics general circulation model (TIME-GCM). We compare and contrast the satellite observations with TIME-GCM results from a realistic simulation based on prevailing meteorological and solar geomagnetic conditions. We diagnose the comparative importance of the upper atmospheric signatures attributable to meteorological forcing with those attributable to storm effects by diagnosing a series of complementary control TIME-GCM simulations. These results also quantify the extent to which lower and middle atmospheric sources of upper atmospheric variability precondition its response to the solar geomagnetic storm.

  10. Ground and CHAMP observations of field-aligned current circuits generated by lower atmospheric disturbances and expectations to the SWARM to clarify their three dimensional structure

    NASA Astrophysics Data System (ADS)

    Iyemori, Toshihiko; Nakanishi, Kunihito; Aoyama, Tadashi; Lühr, Hermann

    2014-05-01

    Acoustic gravity waves propagated to the ionosphere cause dynamo currents in the ionosphere. They divert along geomagnetic field lines of force to another hemisphere accompanying electric field and then flow in the ionosphere of another hemisphere by the electric field forming closed current circuits. The oscillating current circuits with the period of acoustic waves generate magnetic variations on the ground, and they are observed as long period geomagnetic pulsations. This effect has been detected during big earthquakes, strong typhoons, tornados etc. On a low-altitude satellite orbit, the spatial distribution (i.e., structure) of the current circuits along the satellite orbit should be detected as temporal magnetic oscillations, and the effect is confirmed by a CHAMP data analysis. On the spatial structure, in particular, in the longitudinal direction, it has been difficult to examine by a single satellite or from ground magnetic observations. The SWARM satellites will provide an unique opportunity to clarify the three dimensional structure of the field-aligned current circuits.

  11. Suppression of ϒ production in d +Au and Au+Au collisions at √{sNN}=200 GeV

    NASA Astrophysics Data System (ADS)

    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.; Balewski, J.; Banerjee, A.; Barnovska, Z.; 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.; Corliss, R.; 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.; 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.; Grosnick, D.; Guo, Y.; Gupta, A.; Gupta, S.; Guryn, W.; Haag, B.; Hajkova, O.; Hamed, A.; Han, L.-X.; Haque, R.; Harris, J. W.; Hays-Wehle, J. P.; Heppelmann, S.; Hill, K.; Hirsch, A.; Hoffmann, G. W.; Hofman, D. J.; Horvat, S.; Huang, B.; Huang, H. Z.; 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.; Korsch, W.; Kotchenda, L.; 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.; Leight, W.; LeVine, M. J.; Li, C.; Li, W.; Li, X.; Li, X.; Li, Y.; Li, Z. M.; Lima, L. M.; Lisa, M. A.; Liu, F.; Ljubicic, T.; Llope, W. J.; 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.; Munhoz, M. G.; Mustafa, M. K.; Nandi, B. K.; Nasim, Md.; Nayak, T. K.; Nelson, J. M.; Nogach, L. V.; Noh, S. Y.; Novak, J.; Nurushev, S. B.; Odyniec, G.; Ogawa, A.; Oh, K.; Ohlson, A.; Okorokov, V.; Oldag, E. W.; Oliveira, R. A. N.; 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.; Peterson, A.; Pile, P.; Planinic, M.; Pluta, J.; Plyku, D.; Poljak, N.; Porter, J.; Poskanzer, A. M.; Pruthi, N. K.; Przybycien, M.; Pujahari, P. R.; 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.; Sahoo, N. R.; Sahu, P. K.; Sakrejda, I.; Salur, S.; Sandacz, A.; 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.; deSouza, U. G.; Spinka, H. M.; Srivastava, B.; Stanislaus, T. D. S.; Stevens, J. R.; Stock, R.; Strikhanov, M.; Stringfellow, B.; Suaide, A. A. P.; Sumbera, M.; Sun, X.; Sun, X. M.; Sun, Y.; Sun, Z.; Surrow, B.; Svirida, D. N.; Symons, T. J. M.; Szanto de Toledo, 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.; 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.; Walker, 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.; Wimsatt, G.; Wissink, S. W.; Witt, R.; Wu, Y. F.; Xiao, Z.; Xie, W.; Xin, K.; Xu, H.; 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.; 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.

    2014-07-01

    We report measurements of ϒ meson production in p + p, d +Au, and Au +Au collisions using the STAR detector at RHIC. We compare the ϒ yield to the measured cross section in p + p collisions in order to quantify any modifications of the yield in cold nuclear matter using d +Au data and in hot nuclear matter using Au +Au data separated into three centrality classes. Our p + p measurement is based on three times the statistics of our previous result. We obtain a nuclear modification factor for ϒ (1 S + 2 S + 3 S) in the rapidity range | y | < 1 in d +Au collisions of RdAu = 0.79 ± 0.24 (stat.) ± 0.03 (syst.) ± 0.10 (p + p syst.). A comparison with models including shadowing and initial state parton energy loss indicates the presence of additional cold-nuclear matter suppression. Similarly, in the top 10% most-central Au +Au collisions, we measure a nuclear modification factor of RAA = 0.49 ± 0.1 (stat.) ± 0.02 (syst.) ± 0.06 (p + psyst.), which is a larger suppression factor than that seen in cold nuclear matter. Our results are consistent with complete suppression of excited-state ϒ mesons in Au +Au collisions. The additional suppression in Au +Au is consistent with the level expected in model calculations that include the presence of a hot, deconfined Quark-Gluon Plasma. However, understanding the suppression seen in d +Au is still needed before any definitive statements about the nature of the suppression in Au +Au can be made.

  12. 100-MeV proton beam intensity measurement by Au activation analysis using 197Au(p, pn)196Au and 197Au(p, p3n)194Au reactions

    NASA Astrophysics Data System (ADS)

    Mokhtari Oranj, Leila; Jung, Nam-Suk; Oh, Joo-Hee; Lee, Hee-Seock

    2016-05-01

    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 197Au(p, pn)196Au and 197Au(p, p3n)194Au 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.

  13. Electrochemical Characterization of Protein Adsorption onto YNGRT-Au and VLGXE-Au Surfaces

    PubMed Central

    Trzeciakiewicz, Hanna; Esteves-Villanueva, Jose; Soudy, Rania; Kaur, Kamaljit; Martic-Milne, Sanela

    2015-01-01

    The adsorption of the proteins CD13, mucin and bovine serum albumin on VLGXE-Au and YNGRT-Au interfaces was monitored by electrochemical impedance spectroscopy in the presence of [Fe(CN)6]3−/4−. The hydrophobicity of the Au surface was tailored using specific peptides, blocking agents and diluents. The combination of blocking agents (ethanolamine or n-butylamine) and diluents (hexanethiol or 2-mercaptoethanol) was used to prepare various peptide-modified Au surfaces. Protein adsorption onto the peptide-Au surfaces modified with the combination of n-butylamine and hexanethiol produced a dramatic decrease in the charge transfer resistance, Rct, for all three proteins. In contrast, polar peptide-surfaces induced a minimal change in Rct for all three proteins. Furthermore, an increase in Rct was observed with CD13 (an aminopeptidase overexpressed in certain cancers) in comparison to the other proteins when the VLGXE-Au surface was modified with n-butylamine as a blocking agent. The electrochemical data indicated that protein adsorption may be modulated by tailoring the peptide sequence on Au surfaces and that blocking agents and diluents play a key role in promoting or preventing protein adsorption. The peptide-Au platform may also be used for targeting cancer biomarkers with designer peptides. PMID:26262621

  14. Using supported Au nanoparticles as starting material for preparing uniform Au/Pd bimetallic catalysts

    SciTech Connect

    Villa, Alberto; Prati, Laura; Su, Dangshen; Wang, Di; Veith, Gabriel M

    2010-01-01

    One of the best methods for producing bulk homogeneous (composition) supported bimetallic AuPd clusters involves the immobilization of a protected Au seed followed by the addition of Pd. This paper investigates the importance of this gold seed in controlling the resulting bimetallic AuPd clusters structures, sizes and catalytic activities by investigating three different gold seeds. Uniform Au-Pd alloy were obtained when a steric/electrostatic protecting group, poly(vinyl alcohol) (PVA), was used to form the gold clusters on activated carbon (AC). In contrast Au/AC precursors prepared using Au nanoparticles with only electrostatic stabilization (tetrakis(hydroxypropyl)phosphonium chloride (THPC)), or no stabilization (magnetron sputtering) produced inhomogeneous alloys and segregation of the gold and palladium. The uniform alloyed catalyst (Pd{at}Au{sub PVA}/AC) is the most active and selective catalyst, while the inhomogenous catalysts are less active and selective. Further study of the PVA protected Au clusters revealed that the amount of PVA used is also critical for the preparation of uniform alloyed catalyst, their stability, and their catalytic activity.

  15. The extraction characteristic of Au-Ag from Au concentrate by thiourea solution

    NASA Astrophysics Data System (ADS)

    Kim, Bongju; Cho, Kanghee; On, Hyunsung; Choi, Nagchoul; Park, Cheonyoung

    2013-04-01

    The cyanidation process has been used commercially for the past 100 years, there are ores that are not amenable to treatment by cyanide. Interest in alternative lixiviants, such as thiourea, halogens, thiosulfate and malononitrile, has been revived as a result of a major increase in gold price, which has stimulated new developments in extraction technology, combined with environmental concern. The Au extraction process using the thiourea solvent has many advantages over the cyanidation process, including higher leaching rates, faster extraction time and less than toxicity. The purpose of this study was investigated to the extraction characteristic of Au-Ag from two different Au concentrate (sulfuric acid washing and roasting) under various experiment conditions (thiourea concentration, pH of solvent, temperature) by thiourea solvent. The result of extraction experiment showed that the Au-Ag extraction was a fast extraction process, reaching equilibrium (maximum extraction rate) within 30 min. The Au-Ag extraction rate was higher in the roasted concentrate than in the sulfuric acid washing. The higher the Au-Ag extraction rate (Au - 70.87%, Ag - 98.12%) from roasted concentrate was found when the more concentration of thiourea increased, pH decreased and extraction temperature increased. This study informs extraction method basic knowledge when thiourea was a possibility to eco-/economic resources of Au-Ag utilization studies including the hydrometallurgy.

  16. Adsorbate-modified Electron Relaxation in Au-Au_2S Nanoshells

    NASA Astrophysics Data System (ADS)

    Westcott, Sarah; Averitt, Richard; Wolfgang, John; Nordlander, Peter; Halas, Naomi

    2001-03-01

    Au-Au_2S nanoshells are 50 nm nanoparticles consisting of an Au_2S core encapsulated by a thin (<5 nm) Au shell. Their optical properties are determined by the metallic shell layer, whose inner and outer radii control plasmon frequency and whose thickness determines plasmon linewidth[1]. We studied the time-resolved relaxation of hot electrons in the Au shell, using degenerate pump-probe spectroscopy. The electron relaxation for nanoshells in solution was appreciably slower than relaxation for bulk gold, moreover, adsorbed molecules on the nanoshell surface strongly modify this relaxation. Density functional theory calculations indicate that the molecules providing the strongest modification of relaxation possess the largest induced dipole moments above a metal surface, indicating that the adsorbate-induced perturbation of the nanoshell electron dynamics appears to be primarily electronic in nature. [1] R. D. Averitt, D. Sarkar and N. J. Halas, Phys. Rev. Lett. 78, 4217 (1997).

  17. Odd-Even Pattern Observed in Polyaniline/(Au0 – Au8) Composites

    SciTech Connect

    Jonke, Alex P.; Josowicz, Mira A.; Janata, Jiri

    2012-01-12

    Theoretically predicted effect of odd-even pattern of electron pairing on behavior of gold clusters in polyaniline/AuN (N = 0 to 8) has been confirmed experimentally. In these composites the atomic Au clusters with even number of atoms exhibit higher catalytic activity for electrochemical oxidation of n-propanol in 1 M NaOH than the odd-number atoms clusters. Also, infrared spectroscopy shows that even numbered PANI/AuN composites affect the N-H stretching vibration more strongly than the corresponding odd numbered ones. This behavior matches the theoretically predicted variations of HOMO-LUMO gap energy and the stability of the atomic Au clusters. It also agrees with the earlier experimental work in which the UPS spectra of isolated, mass-selected Au clusters have been reported.

  18. Jets and dijets in Au+Au and p+p collisions at RHIC

    SciTech Connect

    Hardtke, D.; STAR Collaboration

    2002-12-09

    Recent data from RHIC suggest novel nuclear effects in the production of high p{sub T} hadrons. We present results from the STAR detector on high p{sub T} angular correlations in Au+Au and p+p collisions at {radical}S = 200 GeV/c. These two-particle angular correlation measurements verify the presence of a partonic hard scattering and fragmentation component at high p{sub T} in both central and peripheral Au+Au collisions. When triggering on a leading hadron with p{sub T}>4 GeV, we observe a quantitative agreement between the jet cone properties in p+p and all centralities of Au+Au collisions. This quantitative agreement indicates that nearly all hadrons with p{sub T}>4 GeV/c come from jet fragmentation and that jet fragmentation properties are not substantially modified in Au+Au collisions. STAR has also measured the strength of back-to-back high p{sub T} charged hadron correlations, and observes a small suppression of the back-to-back correlation strength in peripheral collisions, and a nearly complete disappearance o f back-to-back correlations in central Au+Au events. These phenomena, together with the observed strong suppression of inclusive yields and large value of elliptic flow at high p{sub T}, are consistent with a model where high p{sub T} hadrons come from partons created near the surface of the collision region, and where partons that originate or propagate towards the center of the collision region are substantially slowed or completely absorbed.

  19. Spectra and ratios of identified particles in Au+Au and d+Au collisions at sNN=200 GeV

    NASA Astrophysics Data System (ADS)

    Adare, A.; Afanasiev, S.; Aidala, C.; Ajitanand, N. N.; Akiba, Y.; Al-Bataineh, H.; Alexander, J.; Angerami, A.; Aoki, K.; Apadula, N.; Aramaki, Y.; Atomssa, E. T.; Averbeck, R.; Awes, T. C.; Azmoun, B.; Babintsev, V.; Bai, M.; Baksay, G.; Baksay, L.; Barish, K. N.; Bassalleck, B.; Basye, A. T.; Bathe, S.; Baublis, V.; Baumann, C.; Bazilevsky, A.; Belikov, S.; Belmont, R.; Bennett, R.; Berdnikov, A.; Berdnikov, Y.; Bhom, J. H.; Bickley, A. A.; Blau, D. S.; Bok, J. S.; Boyle, K.; Brooks, M. L.; Buesching, H.; Bumazhnov, V.; Bunce, G.; Butsyk, S.; Camacho, C. M.; Campbell, S.; Caringi, A.; Chen, C.-H.; Chi, C. Y.; Chiu, M.; Choi, I. J.; Choi, J. B.; Choudhury, R. K.; Christiansen, P.; Chujo, T.; Chung, P.; Chvala, O.; Cianciolo, V.; Citron, Z.; Cole, B. A.; Conesa del Valle, Z.; Connors, M.; Constantin, P.; Csanád, M.; Csörgő, T.; Dahms, T.; Dairaku, S.; Danchev, I.; Das, K.; Datta, A.; David, G.; Dayananda, M. K.; Denisov, A.; Deshpande, A.; Desmond, E. J.; Dharmawardane, K. V.; Dietzsch, O.; Dion, A.; Donadelli, M.; Drapier, O.; Drees, A.; Drees, K. A.; Durham, J. M.; Durum, A.; Dutta, D.; D'Orazio, L.; Edwards, S.; Efremenko, Y. V.; Ellinghaus, F.; Engelmore, T.; Enokizono, A.; En'yo, H.; Esumi, S.; Fadem, B.; Fields, D. E.; Finger, M.; Finger, M., Jr.; Fleuret, F.; Fokin, S. L.; Fraenkel, Z.; Frantz, J. E.; Franz, A.; Frawley, A. D.; Fujiwara, K.; Fukao, Y.; Fusayasu, T.; Garishvili, I.; Glenn, A.; Gong, H.; Gonin, M.; Goto, Y.; Granier de Cassagnac, R.; Grau, N.; Greene, S. V.; Grim, G.; Grosse Perdekamp, M.; Gunji, T.; Gustafsson, H.-Å.; Haggerty, J. S.; Hahn, K. I.; Hamagaki, H.; Hamblen, J.; Han, R.; Hanks, J.; Hartouni, E. P.; Haslum, E.; Hayano, R.; He, X.; Heffner, M.; Hemmick, T. K.; Hester, T.; Hill, J. C.; Hohlmann, M.; Holzmann, W.; Homma, K.; Hong, B.; Horaguchi, T.; Hornback, D.; Huang, S.; Ichihara, T.; Ichimiya, R.; Ide, J.; Ikeda, Y.; Imai, K.; Inaba, M.; Isenhower, D.; Ishihara, M.; Isobe, T.; Issah, M.; Isupov, A.; Ivanischev, D.; Iwanaga, Y.; Jacak, B. V.; Jia, J.; Jiang, X.; Jin, J.; Johnson, B. M.; Jones, T.; Joo, K. S.; Jouan, D.; Jumper, D. S.; Kajihara, F.; Kametani, S.; Kamihara, N.; Kamin, J.; Kang, J. H.; Kapustinsky, J.; Karatsu, K.; Kasai, M.; Kawall, D.; Kawashima, M.; Kazantsev, A. V.; Kempel, T.; Khanzadeev, A.; Kijima, K. M.; Kikuchi, J.; Kim, A.; Kim, B. I.; Kim, D. H.; Kim, D. J.; Kim, E.; Kim, E.-J.; Kim, S. H.; Kim, Y.-J.; Kinney, E.; Kiriluk, K.; Kiss, Á.; Kistenev, E.; Kleinjan, D.; Kochenda, L.; Komkov, B.; Konno, M.; Koster, J.; Kotchetkov, D.; Kozlov, A.; Král, A.; Kravitz, A.; Kunde, G. J.; Kurita, K.; Kurosawa, M.; Kwon, Y.; Kyle, G. S.; Lacey, R.; Lai, Y. S.; Lajoie, J. G.; Lebedev, A.; Lee, D. M.; Lee, J.; Lee, K.; Lee, K. B.; Lee, K. S.; Leitch, M. J.; Leite, M. A. L.; Leitner, E.; Lenzi, B.; Li, X.; Lichtenwalner, P.; Liebing, P.; Linden Levy, L. A.; Liška, T.; Litvinenko, A.; Liu, H.; Liu, M. X.; Love, B.; Luechtenborg, R.; Lynch, D.; Maguire, C. F.; Makdisi, Y. I.; Malakhov, A.; Malik, M. D.; Manko, V. I.; Mannel, E.; Mao, Y.; Masui, H.; Matathias, F.; McCumber, M.; McGaughey, P. L.; McGlinchey, D.; Means, N.; Meredith, B.; Miake, Y.; Mibe, T.; Mignerey, A. C.; Mikeš, P.; Miki, K.; Milov, A.; Mishra, M.; Mitchell, J. T.; Mohanty, A. K.; Moon, H. J.; Morino, Y.; Morreale, A.; Morrison, D. P.; Moukhanova, T. V.; Murakami, T.; Murata, J.; Nagamiya, S.; Nagle, J. L.; Naglis, M.; Nagy, M. I.; Nakagawa, I.; Nakamiya, Y.; Nakamura, K. R.; Nakamura, T.; Nakano, K.; Nam, S.; Newby, J.; Nguyen, M.; Nihashi, M.; Nouicer, R.; Nyanin, A. S.; Oakley, C.; O'Brien, E.; Oda, S. X.; Ogilvie, C. A.; Oka, M.; Okada, K.; Onuki, Y.; Oskarsson, A.; Ouchida, M.; Ozawa, K.; Pak, R.; Pantuev, V.; Papavassiliou, V.; Park, I. H.; Park, J.; Park, S. K.; Park, W. J.; Pate, S. F.; Pei, H.; Peng, J.-C.; Pereira, H.; Peresedov, V.; Peressounko, D. Yu.; Petti, R.; Pinkenburg, C.; Pisani, R. P.; Proissl, M.; Purschke, M. L.; Purwar, A. K.; Qu, H.; Rak, J.; Rakotozafindrabe, A.; Ravinovich, I.; Read, K. F.; Rembeczki, S.; Reygers, K.; Riabov, V.; Riabov, Y.; Richardson, E.; Roach, D.; Roche, G.; Rolnick, S. D.; Rosati, M.; Rosen, C. A.; Rosendahl, S. S. E.; Rosnet, P.; Rukoyatkin, P.; Ružička, P.; Sahlmueller, B.; Saito, N.; Sakaguchi, T.; Sakashita, K.; Samsonov, V.; Sano, S.; Sato, T.; Sawada, S.; Sedgwick, K.; Seele, J.; Seidl, R.; Semenov, A. Yu.; Seto, R.; Sharma, D.; Shein, I.; Shibata, T.-A.; Shigaki, K.; Shimomura, M.; Shoji, K.; Shukla, P.; Sickles, A.; Silva, C. L.; Silvermyr, D.; Silvestre, C.; Sim, K. S.; Singh, B. K.; Singh, C. P.; Singh, V.; Slunečka, M.; Soltz, R. A.; Sondheim, W. E.; Sorensen, S. P.; Sourikova, I. V.; Sparks, N. A.; Stankus, P. W.; Stenlund, E.; Stoll, S. P.; Sugitate, T.; Sukhanov, A.; Sziklai, J.; Takagui, E. M.; Taketani, A.; Tanabe, R.; Tanaka, Y.; Taneja, S.; Tanida, K.; Tannenbaum, M. J.; Tarafdar, S.; Taranenko, A.; Tarján, P.; Themann, H.; Thomas, D.; Thomas, T. L.; Togawa, M.; Toia, A.; Tomášek, L.; Torii, H.; Towell, R. S.; Tserruya, I.; Tsuchimoto, Y.; Vale, C.; Valle, H.; van Hecke, H. W.; Vazquez-Zambrano, E.; Veicht, A.; Velkovska, J.; Vértesi, R.; Vinogradov, A. A.; Virius, M.; Vrba, V.; Vznuzdaev, E.; Wang, X. R.; Watanabe, D.; Watanabe, K.; Watanabe, Y.; Wei, F.; Wei, R.; Wessels, J.; White, S. N.; Winter, D.; Wood, J. P.; Woody, C. L.; Wright, R. M.; Wysocki, M.; Xie, W.; Yamaguchi, Y. L.; Yamaura, K.; Yang, R.; Yanovich, A.; Ying, J.; Yokkaichi, S.; You, Z.; Young, G. R.; Younus, I.; Yushmanov, I. E.; Zajc, W. A.; Zhang, C.; Zhou, S.; Zolin, L.

    2013-08-01

    The transverse momentum (pT) spectra and ratios of identified charged hadrons (π±, K±, p, p¯) produced in sNN=200 GeV Au+Au and d+Au collisions are reported in five different centrality classes for each collision species. The measurements of pions and protons are reported up to pT=6 GeV/c (5 GeV/c), and the measurements of kaons are reported up to pT=4 GeV/c (3.5 GeV/c) in Au+Au (d+Au) collisions. In the intermediate pT region, between 2 and 5 GeV/c, a significant enhancement of baryon-to-meson ratios compared to those measured in p+p collisions is observed. This enhancement is present in both Au+Au and d+Au collisions and increases as the collisions become more central. We compare a class of peripheral Au+Au collisions with a class of central d+Au collisions which have a comparable number of participating nucleons and binary nucleon-nucleon collisions. The pT-dependent particle ratios for these classes display a remarkable similarity, which is then discussed.

  20. Synthesis and characterization in AuCu–Si nanostructures

    SciTech Connect

    Novelo, T.E.; Amézaga-Madrid, P.; Maldonado, R.D.; Oliva, A.I.; Alonzo-Medina, G.M.

    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.

  1. Au nanoparticles films used in biological sensing

    NASA Astrophysics Data System (ADS)

    Rosales Pérez, M.; Delgado Macuil, R.; Rojas López, M.; Gayou, V. L.; Sánchez Ramírez, J. F.

    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-1 due to surface enhancement infrared absorption.

  2. A velocity map imaging study of gold-rare gas complexes: Au-Ar, Au-Kr, and Au-Xe

    NASA Astrophysics Data System (ADS)

    Hopkins, W. Scott; Woodham, Alex P.; Plowright, Richard J.; Wright, Timothy G.; Mackenzie, Stuart R.

    2010-06-01

    The ultraviolet photodissociation dynamics of the gold-rare gas atom van der Waals complexes (Au-RG, RG=Ar, Kr, and Xe) have been studied by velocity map imaging. Photofragmentation of Au-Ar and Au-Kr at several wavelengths permits extrapolation to zero of the total kinetic energy release (TKER) spectra as monitored in the Au(P23/2∘[5d106p]) fragment channel, facilitating the determination of ground state dissociation energies of D0″(Au-Ar)=149±13 cm-1 and D0″(Au-Kr)=240±19 cm-1, respectively. In the same spectral region, transitions to vibrational levels of an Ω'=1/2 state of the Au-Xe complex result in predissociation to the lower Au(P21/2∘[5d106p])+Xe(S10[5p6]) fragment channel for which TKER extrapolation yields a value of D0″(Au-Xe)=636±27 cm-1. Asymmetric line shapes for transitions to the v'=14 level of this state indicate coupling to the Au(P23/2∘[5d106p])+Xe(S10[5p6]) continuum, which allows us to refine this value to D0″(Au-Xe)=607±5 cm-1. The dissociation dynamics of this vibrational level have been studied at the level of individual isotopologues by fitting the observed excitation spectra to Fano profiles. These fits reveal a remarkable variation in the predissociation dynamics for different Au-Xe isotopologues. For Au-Ar and Au-Xe, the determined ground state dissociation energies are in good agreement with recent theoretical calculations; the agreement of the Au-Kr value with theory is less satisfactory.

  3. Seasonal and Latitudinal Variations of the Electron Density Nonmigrating Tidal Spectrum in the Topside Ionospheric F-Region As Resolved from CHAMP Observations

    NASA Astrophysics Data System (ADS)

    Xiong, C.; Luhr, H.; Stolle, C.

    2014-12-01

    In this study we present for the first time the nonmigrating tidal spectrum for the electron density in the topside ionosphere on global scale for different seasons at both solar maximum and minimum conditions. The electron density observations from the CHAMP (CHAllenging Minisatellite Payload) satellite provide evidence for prominent nonmigrating tides at different latitude regions. The diurnal tides DE1, D0, and DW2 appear preferably at middle and high latitudes during all the seasons. DE1 is only found in the northern middle and high latitudes, while D0 and DW2 are much stronger in the southern hemisphere. These tides are believed to be driven by the thermospheric winds through ion-neutral interactions. The semidiurnal tides SW1 and SW3 can also be found with appreciable amplitudes throughout the whole year at low and middle latitudes, but preferably during equinox seasons. At equatorial and low latitude regions the most prominent diurnal tides are DE2 and DE3. DE2 is found to be present at low latitude regions throughout the whole year with larger amplitudes in the southern hemisphere, while DE3 shows largest amplitudes (symmetric above the dip equator) at the EIA crest region during September solstice. A general anti-phase behavior between the EIA crest and trough is observed for the tides DE3, DE2, DW2 and SW3. We consider this as strong evidence for the modulation of the EIA electron density by the E-layer zonal electric field via the ion fountain effect. An exception makes the tidal component D0, which exhibits anti-phase variations between the two hemispheres. The phase value at the equatorial trough is half way between those of the two hemispheres. Presently we cannot give an explanation for it, and study concerning special model effort is further needed.

  4. Superposed epoch analysis of vertical plasma flow and its relationship with FACs as observed by DMSP and CHAMP: IMF By and Bx dependence

    NASA Astrophysics Data System (ADS)

    Kervalishvili, Guram; Lühr, Hermann

    2016-04-01

    This study presents results of a superposed epoch analysis (SEA) method applied to vertical plasma flow and large-scale field aligned currents (FACs) in the Northern Hemisphere cusp region. Our study is based on DMSP (F13 and F15) and CHAMP satellite observations during the years 2001-2005. Interplanetary magnetic field (IMF) data were taken from the NASA/GSFC's OMNI online database. The dependence on IMF By and Bx component orientation is investigated, while the absolute amplitude of IMF Bz is selected to be less than 2 nT. Seasonal variations are also investigated with seasons defined as follows: local winter (1 January ± 65 days), combined equinoxes (1 April and 1 October ± 32 days), and local summer (1 July ± 65 days). The reference time and location for the SEA method are taken from the vertical ion velocity peaks (> 100 m/s for upflow and <-100 m/s for downflow) detected by DMSP in the northern cusp region. Our analyses were performed in the magnetic latitude (MLat) and local time (MLT) coordinate system. In general the vertical plasma downflow is weaker than the upflow. This product, ion density times velocity, shows no dependence on the IMF By orientation, while its value increases towards local summer. The ion density is low in winter and increases towards local summer, while the vertical velocity is much higher in local winter than during equinoxes or local summer. The event number distribution (in MLat-MLT frame) of vertical ion velocity peaks shows no significant dependence on the given conditions. In case of large-scale FACs a clear dependence on IMF By orientation and local season emerges from SEA analysis. Similarly to the vertical plasma upflow, the amplitude of large-scale FACs is also increasing towards local summer. Large-scale FACs show an IMF By dependent regular pattern for upflow cases and no regular pattern for downflow cases in all considered cases.

  5. Advanced Observation Operators for GPS Radio Occultation. Part 1; Validation of the 2D Ray Tracing Approach with CHAMP and SAC-C bending angle and refractivity data

    NASA Technical Reports Server (NTRS)

    Poli, P.; Joiner, J.

    2003-01-01

    Global Positioning System (GPS) Radio Occultations (RO) bending angles and refractivity data characterize mostly the vertical structure of the Earth's atmosphere. We answer the question whether proper simulation of GPS RO data for data assimilation can be obtained with one-dimensional vertical operators, or if accounting also for horizontal atmospheric structures via ray-tracing makes a positive difference when compared with real data. We present a detailed implementation of a geometrical optics multi-plane two-dimensional (2D) ray-tracing as an observation operator to simulate GPS RO bending angles and refractivities within the Finite Volume Data Assimilation System (FVDAS). Comparisons of the outputs of that 2D observation operator with those of simpler ID observation operators are used to generate estimates of errors induced by neglecting tangent point drift (TPD) and horizontal gradients (HG). These error estimates are then confronted with errors estimates derived using 6335 real CHAMP and SAC-C occultations. The agreement for TPD-induced (HG-induced) errors is remarkably positive at altitudes 10-30 km (below 10 km). Comparisons in bending angles O - B STD of the outputs of the multi-plane 2D ray-tracer with those of a vertical Abel transform show reductions of about 8% of the usual O - B bending angle STD due to TPD in the stratosphere (3% due to HG, in the troposphere only). In terms of refractivity, the O - B STD reductions are about 1520% for TPD and 3-5% for HG in the same regions. These reductions are obtained using either 6-hour forecasts or analyses as backgrounds, and using Geometrical Optics (GO) or Canonical Transform (CT) data.

  6. IMF Dependence of High-Latitude Thermospheric Wind Pattern Derived from CHAMP Cross-Track Accelerometer Data and the Corresponding Magnetospheric Convection from Cluster EDI Measurements

    NASA Astrophysics Data System (ADS)

    Foerster, Matthias; Haaland, Stein E.; Rentz, Stefanie; Liu, Huixin

    Neutral thermospheric wind pattern at high latitudes obtained from cross-track acceleration measurements of the CHAMP satellite above both North and South polar regions are statistically analyzed in their dependence on the Interplanetary Magnetic Field (IMF) direction in the GSM y-z plane (clock angle). We compare this dependency with magnetospheric convection pattern using 1-min-averages of Cluster/EDI electric drift observations and the same IMF and solar wind sorting conditions. The spatially distributed Cluster/EDI measurements are mapped to a the common reference level at ionospheric F-region heights in a magnetic latitude/MLT grid. We obtained both regular thermospheric wind and plasma drift pattern according to the various IMF conditions. The IMF-dependency shows some similarity with the corresponding high-latitude plasma convection insofar that the larger-scale convection cells, in particular the round-shaped dusk cell for IMF By+ (By-) conditions at the Northern (Southern) Hemisphere, leave their marks on the dominant general transpolar wind circulation from the dayside to the nightside. The direction of the transpolar circulation is generally deflected toward a duskward flow, in particular in the evening to nighttime sector. The degree of deflection correlates with the IMF clock angle. It is larger for IMF By+ than for Byand is systematically larger (about 5 deg) and appear less structured at the Southern Hemisphere compared with the Northern. Thermospheric cross-polar wind amplitudes are largest for IMF Bz-/Byconditions (corresponding to sector 5) at the Northern Hemisphere, but for IMF Bz-/By+ conditions (sector 3) at the Southern because the magnetospheric convection is in favour of largest wind accelerations over the polar cap under these conditions. The overall variance of the thermospheric wind magnitude at Southern high latitudes is larger than for the Northern. This is probably due to a larger "stirring effect" at the Southern Hemisphere because

  7. Antiproton distributions in Au+nucleus collisions

    SciTech Connect

    Beavis, D.; Debbe, R.; Bennett, M.J.; Chikanian, A.; Kumar, B.S.; Nagle, J.L.; Pope, J.K.; Carroll, J.B.; Hallman, T.J.; Chiba, J.; Tanaka, K.H.; Crawford, H.J.; Cronqvist, M.; Dardenne, Y.; Engelage, J.; Greiner, L.; Kuo, C.; Doke, T.; Kashiwagi, T.; Kikuchi, J.; Hayano, R.S.; Heckman, H.H.; Lindstrom, P.J.; Mitchell, J.W.; Welsh, R.C.

    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}

  8. The role of interfaces in the magnetoresistance of Au/Fe/Au/Fe/GaAs(001)

    SciTech Connect

    Enders, A.; Monchesky, T. L.; Myrtle, K.; Urban, R.; Heinrich, B.; Kirschner, J.; Zhang, X.-G.; Butler, W. H.

    2001-06-01

    The electron transport and magnetoresistance (MR) were investigated in high quality crystalline epitaxial Fe(001) and Au(001) films and exchange coupled Au/Fe/Au/Fe/GaAs(001) trilayer structures. Fits to the experimental data were based on the semiclassical Boltzmann equation, which incorporates the electronic properties obtained from first-principles local density functional calculations. The fits require a surprisingly high asymmetry for the spin dependent electron lifetimes in Fe, {tau}{sup {down_arrow}}/{tau}{sup {up_arrow}}=10 at room temperature. Despite the large atomic terraces at the Au/vacuum and Fe/GaAs interfaces the scattering at the outer interfaces was found to be diffuse. The origin of MR in Au/Fe/Au/Fe/GaAs(001) structures is due to electron channeling in the Au spacer layer. The measured MR is consistent with the diffusivity parameters s{sup {up_arrow}}=0.55, s{sup {down_arrow}}=0.77 at the metal{endash}metal interfaces. {copyright} 2001 American Institute of Physics.

  9. Robust Au-Ag-Au bimetallic atom-scale junctions fabricated by self-limited Ag electrodeposition at Au nanogaps.

    PubMed

    Hwang, Tai-Wei; Bohn, Paul W

    2011-10-25

    Atom-scale junctions (ASJs) exhibit quantum conductance behavior and have potential both for fundamental studies of adsorbate-mediated conductance in mesoscopic conductors and as chemical sensors. Electrochemically fabricated ASJs, in particular, show the stability needed for molecular detection applications. However, achieving physically robust ASJs at high yield is a challenge because it is difficult to control the direction and kinetics of metal deposition. In this work, a novel electrochemical approach is reported, in which Au-Ag-Au bimetallic ASJs are reproducibly fabricated from an initially prepared Au nanogap by sequential overgrowth and self-limited thinning. Applying a potential across specially prepared Au nanoelectrodes in the presence of aqueous Ag(I) leads to preferential galvanic reactions resulting in the deposition of Ag and the formation of an atom-scale junction between the electrodes. An external resistor is added in series with the ASJ to control self-termination, and adjusting solution chemical potential (concentration) is used to mediate self-thinning of junctions. The result is long-lived, mechanically stable ASJs that, unlike previous constructions, are stable in flowing solution, as well as to changes in solution media. These bimetallic ASJs exhibit a number of behaviors characteristic of quantum structures, including long-lived fractional conductance states, that are interpreted to arise from two or more quantized ASJs in series.

  10. Fabrication of segmented Au/Co/Au nanowires: insights in the quality of Co/Au junctions.

    PubMed

    Jang, Bumjin; Pellicer, Eva; Guerrero, Miguel; Chen, Xiangzhong; Choi, Hongsoo; Nelson, Bradley J; Sort, Jordi; Pané, Salvador

    2014-08-27

    Electrodeposition is a versatile method, which enables the fabrication of a variety of wire-like nanoarchitectures such as nanowires, nanorods, and nanotubes. By means of template-assisted electrodeposition, segmented Au/Co/Au nanowires are grown in anodic aluminum oxide templates from two different electrolytes. To tailor the properties of the cobalt segments, several electrochemical conditions are studied as a function of current density, pulse deposition, and pH. The morphology, crystal structure, and magnetic properties are accordingly investigated. Changes in the deposition conditions affect the cobalt electrocrystallization process directly. Cobalt tends to crystallize mainly in the hexagonal close-packed structure, which is the reason cobalt might not accommodate satisfactorily on the face-centered cubic Au surface or vice versa. We demonstrate that by modifying the electrolyte and the applied current densities, changes in the texture and the crystalline structure of cobalt lead to a good quality connection between dissimilar segments. In particular, lowering the bath pH, or using pulse plating at a high overpotential, produces polycrystalline fcc Co and thus well-connected Co/Au bimetallic junctions with smooth interface. These are crucial factors to be carefully considered taking into account that nanowires are potential building blocks in micro- and nanoelectromechanical systems. PMID:25025496

  11. Production of ω mesons in p + p, d + Au, Cu + Cu, and Au + Au collisions at sNN=200 GeV

    NASA Astrophysics Data System (ADS)

    Adare, A.; Afanasiev, S.; Aidala, C.; Ajitanand, N. N.; Akiba, Y.; Al-Bataineh, H.; Al-Jamel, A.; Alexander, J.; Angerami, A.; Aoki, K.; Apadula, N.; Aphecetche, L.; Aramaki, Y.; Armendariz, R.; Aronson, S. H.; Asai, J.; Atomssa, E. T.; Averbeck, R.; Awes, T. C.; Azmoun, B.; Babintsev, V.; Bai, M.; Baksay, G.; Baksay, L.; Baldisseri, A.; Barish, K. N.; Barnes, P. D.; Bassalleck, B.; Basye, A. T.; Bathe, S.; Batsouli, S.; Baublis, V.; Bauer, F.; Baumann, C.; Bazilevsky, A.; Belikov, S.; Belmont, R.; Bennett, R.; Berdnikov, A.; Berdnikov, Y.; Bhom, J. H.; Bickley, A. A.; Bjorndal, M. T.; Blau, D. S.; Boissevain, J. G.; Bok, J. S.; Borel, H.; Boyle, K.; Brooks, M. L.; Brown, D. S.; Bucher, D.; Buesching, H.; Bumazhnov, V.; Bunce, G.; Burward-Hoy, J. M.; Butsyk, S.; Camacho, C. M.; Campbell, S.; Caringi, A.; Chai, J.-S.; Chang, B. S.; Charvet, J.-L.; Chen, C.-H.; Chernichenko, S.; Chi, C. Y.; Chiba, J.; Chiu, M.; Choi, I. J.; Choi, J. B.; Choudhury, R. K.; Christiansen, P.; Chujo, T.; Chung, P.; Churyn, A.; Chvala, O.; Cianciolo, V.; Citron, Z.; Cleven, C. R.; Cobigo, Y.; Cole, B. A.; Comets, M. P.; Conesa Del Valle, Z.; Connors, M.; Constantin, P.; Csanád, M.; Csörgő, T.; Dahms, T.; Dairaku, S.; Danchev, I.; Das, K.; Datta, A.; David, G.; Dayananda, M. K.; Deaton, M. B.; Dehmelt, K.; Delagrange, H.; Denisov, A.; D'Enterria, D.; Deshpande, A.; Desmond, E. J.; Dharmawardane, K. V.; Dietzsch, O.; Dion, A.; Donadelli, M.; Drachenberg, J. L.; Drapier, O.; Drees, A.; Drees, K. A.; Dubey, A. K.; Durham, J. M.; Durum, A.; Dutta, D.; Dzhordzhadze, V.; D'Orazio, L.; Edwards, S.; Efremenko, Y. V.; Egdemir, J.; Ellinghaus, F.; Emam, W. S.; Engelmore, T.; Enokizono, A.; En'yo, H.; Espagnon, B.; Esumi, S.; Eyser, K. O.; Fadem, B.; Fields, D. E.; Finger, M.; Finger, M., Jr.; Fleuret, F.; Fokin, S. L.; Forestier, B.; Fraenkel, Z.; Frantz, J. E.; Franz, A.; Frawley, A. D.; Fujiwara, K.; Fukao, Y.; Fung, S.-Y.; Fusayasu, T.; Gadrat, S.; Garishvili, I.; Gastineau, F.; Germain, M.; Glenn, A.; Gong, H.; Gonin, M.; Gosset, J.; Goto, Y.; Granier de Cassagnac, R.; Grau, N.; Greene, S. V.; Grim, G.; Grosse Perdekamp, M.; Gunji, T.; Gustafsson, H.-Å.; Hachiya, T.; Hadj Henni, A.; Haegemann, C.; Haggerty, J. S.; Hagiwara, M. N.; Hahn, K. I.; Hamagaki, H.; Hamblen, J.; Han, R.; Hanks, J.; Harada, H.; Hartouni, E. P.; Haruna, K.; Harvey, M.; Haslum, E.; Hasuko, K.; Hayano, R.; He, X.; Heffner, M.; Hemmick, T. K.; Hester, T.; Heuser, J. M.; Hiejima, H.; Hill, J. C.; Hobbs, R.; Hohlmann, M.; Holmes, M.; Holzmann, W.; Homma, K.; Hong, B.; Horaguchi, T.; Hornback, D.; Huang, S.; Hur, M. G.; Ichihara, T.; Ichimiya, R.; Ide, J.; Iinuma, H.; Ikeda, Y.; Imai, K.; Inaba, M.; Inoue, Y.; Isenhower, D.; Isenhower, L.; Ishihara, M.; Isobe, T.; Issah, M.; Isupov, A.; Ivanischev, D.; Iwanaga, Y.; Jacak, B. V.; Jia, J.; Jiang, X.; Jin, J.; Jinnouchi, O.; Johnson, B. M.; Jones, T.; Joo, K. S.; Jouan, D.; Jumper, D. S.; Kajihara, F.; Kametani, S.; Kamihara, N.; Kamin, J.; Kaneta, M.; Kang, J. H.; Kanou, H.; Kapustinsky, J.; Karatsu, K.; Kasai, M.; Kawagishi, T.; Kawall, D.; Kawashima, M.; Kazantsev, A. V.; Kelly, S.; Kempel, T.; Khanzadeev, A.; Kijima, K. M.; Kikuchi, J.; Kim, A.; Kim, B. I.; Kim, D. H.; Kim, D. J.; Kim, E.; Kim, E. J.; Kim, S. H.; Kim, Y.-J.; Kim, Y.-S.; Kim, Y. J.; Kinney, E.; Kiriluk, K.; Kiss, Á.; Kistenev, E.; Kiyomichi, A.; Klay, J.; Klein-Boesing, C.; Kochenda, L.; Kochetkov, V.; Komkov, B.; Konno, M.; Koster, J.; Kotchetkov, D.; Kozlov, A.; Král, A.; Kravitz, A.; Kroon, P. J.; Kubart, J.; Kunde, G. J.; Kurihara, N.; Kurita, K.; Kurosawa, M.; Kweon, M. J.; Kwon, Y.; Kyle, G. S.; Lacey, R.; Lai, Y. S.; Lajoie, J. G.; Lebedev, A.; Le Bornec, Y.; Leckey, S.; Lee, D. M.; Lee, J.; Lee, K.; Lee, K. B.; Lee, K. S.; Lee, M. K.; Lee, T.; Leitch, M. J.; Leite, M. A. L.; Leitner, E.; Lenzi, B.; Li, X.; Li, X. H.; Lichtenwalner, P.; Liebing, P.; Lim, H.; Linden Levy, L. A.; Liška, T.; Litvinenko, A.; Liu, H.; Liu, M. X.; Love, B.; Luechtenborg, R.; Lynch, D.; Maguire, C. F.; Makdisi, Y. I.; Malakhov, A.; Malik, M. D.; Manko, V. I.; Mannel, E.; Mao, Y.; Mašek, L.; Masui, H.; Matathias, F.; McCain, M. C.; McCumber, M.; McGaughey, P. L.; Means, N.; Meredith, B.; Miake, Y.; Mibe, T.; Mignerey, A. C.; Mikeš, P.; Miki, K.; Miller, T. E.; Milov, A.; Mioduszewski, S.; Mishra, G. C.; Mishra, M.; Mitchell, J. T.; Mitrovski, M.; Mohanty, A. K.; Moon, H. J.; Morino, Y.; Morreale, A.; Morrison, D. P.; Moss, J. M.; Moukhanova, T. V.; Mukhopadhyay, D.; Murakami, T.; Murata, J.; Nagamiya, S.; Nagata, Y.; Nagle, J. L.; Naglis, M.; Nagy, M. I.; Nakagawa, I.; Nakamiya, Y.; Nakamura, K. R.; Nakamura, T.; Nakano, K.; Nam, S.; Newby, J.; Nguyen, M.; Nihashi, M.; Norman, B. E.; Nouicer, R.; Nyanin, A. S.; Nystrand, J.; Oakley, C.; O'Brien, E.; Oda, S. X.; Ogilvie, C. A.; Ohnishi, H.; Ojha, I. D.; Oka, M.; Okada, K.; Omiwade, O. O.; Onuki, Y.; Oskarsson, A.; Otterlund, I.; Ouchida, M.; Ozawa, K.; Pak, R.; Pal, D.; Palounek, A. P. T.; Pantuev, V.; Papavassiliou, V.; Park, I. H.; Park, J.; Park, S. K.; Park, W. J.; Pate, S. F.; Pei, H.; Peng, J.-C.; Pereira, H.; Peresedov, V.; Peressounko, D. Yu.; Petti, R.; Pinkenburg, C.; Pisani, R. P.; Proissl, M.; Purschke, M. L.; Purwar, A. K.; Qu, H.; Rak, J.; Rakotozafindrabe, A.; Ravinovich, I.; Read, K. F.; Rembeczki, S.; Reuter, M.; Reygers, K.; Riabov, V.; Riabov, Y.; Richardson, E.; Roach, D.; Roche, G.; Rolnick, S. D.; Romana, A.; Rosati, M.; Rosen, C. A.; Rosendahl, S. S. E.; Rosnet, P.; Rukoyatkin, P.; Ružička, P.; Rykov, V. L.; Ryu, S. S.; Sahlmueller, B.; Saito, N.; Sakaguchi, T.; Sakai, S.; Sakashita, K.; Sakata, H.; Samsonov, V.; Sano, S.; Sato, H. D.; Sato, S.; Sato, T.; Sawada, S.; Sedgwick, K.; Seele, J.; Seidl, R.; Semenov, A. Yu.; Semenov, V.; Seto, R.; Sharma, D.; Shea, T. K.; Shein, I.; Shevel, A.; Shibata, T.-A.; Shigaki, K.; Shimomura, M.; Shohjoh, T.; Shoji, K.; Shukla, P.; Sickles, A.; Silva, C. L.; Silvermyr, D.; Silvestre, C.; Sim, K. S.; Singh, B. K.; Singh, C. P.; Singh, V.; Skutnik, S.; Slunečka, M.; Smith, W. C.; Soldatov, A.; Soltz, R. A.; Sondheim, W. E.; Sorensen, S. P.; Sourikova, I. V.; Sparks, N. A.; Staley, F.; Stankus, P. W.; Stenlund, E.; Stepanov, M.; Ster, A.; Stoll, S. P.; Sugitate, T.; Suire, C.; Sukhanov, A.; Sullivan, J. P.; Sziklai, J.; Tabaru, T.; Takagi, S.; Takagui, E. M.; Taketani, A.; Tanabe, R.; Tanaka, K. H.; Tanaka, Y.; Taneja, S.; Tanida, K.; Tannenbaum, M. J.; Tarafdar, S.; Taranenko, A.; Tarján, P.; Themann, H.; Thomas, D.; Thomas, T. L.; Togawa, M.; Toia, A.; Tojo, J.; Tomášek, L.; Torii, H.; Towell, R. S.; Tram, V.-N.; Tserruya, I.; Tsuchimoto, Y.; Tuli, S. K.; Tydesjö, H.; Tyurin, N.; Vale, C.; Valle, H.; van Hecke, H. W.; Vazquez-Zambrano, E.; Veicht, A.; Velkovska, J.; Vértesi, R.; Vinogradov, A. A.; Virius, M.; Vrba, V.; Vznuzdaev, E.; Wagner, M.; Walker, D.; Wang, X. R.; Watanabe, D.; Watanabe, K.; Watanabe, Y.; Wei, F.; Wei, R.; Wessels, J.; White, S. N.; Willis, N.; Winter, D.; Wood, J. P.; Woody, C. L.; Wright, R. M.; Wysocki, M.; Xie, W.; Yamaguchi, Y. L.; Yamaura, K.; Yang, R.; Yanovich, A.; Yasin, Z.; Ying, J.; Yokkaichi, S.; You, Z.; Young, G. R.; Younus, I.; Yushmanov, I. E.; Zajc, W. A.; Zaudtke, O.; Zhang, C.; Zhou, S.; Zimányi, J.; Zolin, L.

    2011-10-01

    The PHENIX experiment at the Relativistic Heavy Ion Collider has measured ω meson production via leptonic and hadronic decay channels in p+p, d+Au, Cu+Cu, and Au+Au collisions at sNN = 200 GeV. The invariant transverse momentum spectra measured in different decay modes give consistent results. Measurements in the hadronic decay channel in Cu+Cu and Au+Au collisions show that ω production has a suppression pattern at high transverse momentum, similar to that of π0 and η in central collisions, but no suppression is observed in peripheral collisions. The nuclear modification factors, RAA, are consistent in Cu+Cu and Au+Au collisions at similar numbers of participant nucleons.

  12. Facile Syntheses of Monodisperse Ultra-Small Au Clusters

    SciTech Connect

    Bertino, Massimo F.; Sun, Zhong-Ming; Zhang, Rui; Wang, Lai S.

    2006-11-02

    During our effort to synthesize the tetrahedral Au20 cluster, we found a facile synthetic route to prepare monodisperse suspensions of ultra-small Au clusters AuN (N<12) using diphosphine ligands. In our monophasic and single-pot synthesis, a Au precursor ClAu(I)PPh3 and a bidentate phosphine ligand P(Ph)2(CH2)MP(Ph)2 (Ph = phenyl) are dissolved in an organic solvent. Au(I) is reduced slowly by a borane-tert-butylamine complex to form Au clusters coordinated by the diphosphine ligand. The Au clusters are characterized by both high resolution mass spectrometry and UV-Vis absorption spectroscopy. We found that the mean cluster size obtained depends on the chain length M of the ligand. In particular, a single monodispersed Au11 cluster is obtained with the P(Ph)2(CH2)3P(Ph)2 ligand, whereas P(Ph)2(CH2)MP(Ph)2 ligands with M = 5 and 6 yield Au10 and Au8 clusters. The simplicity of our synthetic method makes it suitable for large-scale production of nearly monodisperse ultrasmall Au clusters. It is suggested that diphosphines provide a set of flexible ligands to allow size-controlled synthesis of Au nanoparticles.

  13. Suppression of Upsilon production in d + Au and Au + Au collisions at root s(NN) = 200 GeV (vol 735, pg 127, 2014)

    SciTech Connect

    Adamczyk, L.; Adkins, J. K.; Agakishiev, G.; Aggarwal, M. M.; Ahammed, Z.; Alekseev, I.; Alford, J.; Anson, C. D.; Aparin, A.; Arkhipkin, D.; Gliske, S.; Krueger, K.; Spinka, H. M.; Underwood, D. G.

    2014-07-30

    We report measurements of Υ meson production in p + p, d +Au, and Au+Aucollisions using the STAR detector at RHIC. We compare the Υ yield to the measured cross section in p + p collisions in order to quantify any modifications of the yield in cold nuclear matter using d +Au data and in hot nuclear matter using Au+Au data separated into three centrality classes. Our p +p measurement is based on three times the statistics of our previous result. We obtain a nuclear modification factor for Υ (1S + 2S + 3S) in the rapidity range |y| < 1 in d + Aucollisions of RdAu = 0.79 ± 0.24(stat.) ± 0.03(syst.) ± 0.10(p + p syst.). A comparison with models including shadowing and initial state parton energy loss indicates the presence of additional cold-nuclear matter suppression. Similarly, in the top 10% most-central Au + Au collisions, we measure a nuclear modification factor of R AA = 0.49 ±0.1(stat.) ±0.02(syst.) ±0.06(p + p syst.), which is a larger suppression factor than that seen in cold nuclear matter. Our results are consistent with complete suppression of excited-state Υ mesons in Au + Aucollisions. The additional suppression in Au + Au is consistent with the level expected in model calculations that include the presence of a hot, deconfined Quark–Gluon Plasma. However, understanding the suppression seen in d + Au is still needed before any definitive statements about the nature of the suppression in Au + Au can be made.

  14. Nanoporous Au: an unsupported pure gold catalyst?

    SciTech Connect

    Wittstock, A; Neumann, B; Schaefer, A; Dumbuya, K; Kuebel, C; Biener, M; Zielasek, V; Steinrueck, H; Gottfried, M; Biener, J; Hamza, A; B?umer, M

    2008-09-04

    The unique properties of gold especially in low temperature CO oxidation have been ascribed to a combination of various effects. In particular, particle sizes below a few nm and specific particle-support interactions have been shown to play important roles. On the contrary, recent reports revealed that monolithic nanoporous gold (npAu) prepared by leaching a less noble metal, such as Ag, out of the corresponding alloy can also exhibit remarkably high catalytic activity for CO oxidation, even though no support is present. Therefore, it was claimed to be a pure and unsupported gold catalyst. We investigated npAu with respect to its morphology, surface composition and catalytic properties. In particular, we studied the reaction kinetics for low temperature CO oxidation in detail taking mass transport limitation due to the porous structure of the material into account. Our results reveal that Ag, even if removed almost completely from the bulk, segregates to the surface resulting in surface concentrations of up to 10 at%. Our data suggest that this Ag plays a significant role in activation of molecular oxygen. Therefore, npAu should be considered as a bimetallic catalyst rather than a pure Au catalyst.

  15. 22 CFR 62.31 - Au pairs.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... pair participant with child development and child safety instruction, as follows: (1) Prior to... development instruction of which no less than 4 shall be devoted to specific training for children under the... and participate directly in the home life of the host family. All au pair participants provide...

  16. 22 CFR 62.31 - Au pairs.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... pair participant with child development and child safety instruction, as follows: (1) Prior to... development instruction of which no less than 4 shall be devoted to specific training for children under the... and participate directly in the home life of the host family. All au pair participants provide...

  17. 22 CFR 62.31 - Au pairs.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... pair participant with child development and child safety instruction, as follows: (1) Prior to... development instruction of which no less than 4 shall be devoted to specific training for children under the... and participate directly in the home life of the host family. All au pair participants provide...

  18. 22 CFR 62.31 - Au pairs.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... pair participant with child development and child safety instruction, as follows: (1) Prior to... development instruction of which no less than 4 shall be devoted to specific training for children under the... and participate directly in the home life of the host family. All au pair participants provide...

  19. 22 CFR 62.31 - Au pairs.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... pair participant with child development and child safety instruction, as follows: (1) Prior to... development instruction of which no less than 4 shall be devoted to specific training for children under the... and participate directly in the home life of the host family. All au pair participants provide...

  20. Electron transmission characteristics of Au/1,4-benzenedithiol/Au junctions.

    PubMed

    Horiguchi, K; Tsutsui, M; Kurokawa, S; Sakai, A

    2009-01-14

    Electron transmission through individual 1,4-benzenedithiol molecules bridging between two gold electrodes (Au/BDT/Au junctions) has been studied by measuring the current-voltage (I-V) characteristics. Measurements were made at room temperature on three junction states of conductance 0.005G(0), 0.01G(0), and 0.1G(0), respectively, where G(0) is the quantum unit of conductance. All I-V curves are linear around zero bias and nonlinearly increase upward for biases above approximately 0.2 V. Absence of plateaus in the observed I-V characteristics up to +/- 1 V indicates that the electron transmission spectrum of Au/BDT/Au has no peaks within +/- 0.5 eV from the Fermi level.

  1. High Resolution Photoelectron Spectroscopy of Au_2^- and Au_4^- by Photoelectron Imaging

    NASA Astrophysics Data System (ADS)

    Leon, Iker; Yang, Zheng; Wang, Lai-Sheng

    2013-06-01

    We report high resolution photoelectron spectra of Au_2^- and Au_4^- obtained with a newly-built photoelectron imaging apparatus. Gold anions are produced by laser vaporization and the desired specie is mass selected and focused into the collinear velocity-map imaging (VMI) lens assembly. The design of the imaging lens has allowed us to obtain less than 0.9% energy resolution for high kinetic energy electrons ( > 1eV) while maintaining wavenumber resolution for low kinetic energy electrons. Although gold dimer and tetramer have been studied in the past, we present spectroscopic results under high resolution. For Au_2^-, we report high resolution spectra with an accurate determination of the electron affinity together with a complete vibrational assignment, for both the anion and neutral ground states, while for Au_4^-, we are able to resolve a low frequency mode and obtain accurately the adiabatic detachment energy.

  2. Charged-Particle Pseudorapidity Density Distributions from Au+Au Collisions at

    SciTech Connect

    Back, B. B.; Baker, M. D.; Barton, D. S.; Betts, R. R.; Bindel, R.; Budzanowski, A.; Busza, W.; Carroll, A.; Decowski, M. P.; Garcia, E.

    2001-09-03

    The charged-particle pseudorapidity density dN{sub ch}/d{eta} has been measured for Au+Au collisions at s{sub NN}=130 GeV at RHIC, using the PHOBOS apparatus. The total number of charged particles produced for the 3% most-central Au+Au collisions for |{eta}|{<=}5.4 is found to be 4200{+-}470 . The evolution of dN{sub ch}/d{eta} with centrality is discussed, and compared to model calculations and to data from proton-induced collisions. The data show an enhancement in charged-particle production at midrapidity, while in the fragmentation regions, the results are consistent with expectations from pp and pA scattering.

  3. Systematics of Global Observables in Cu+Cu and Au+Au Collisions at RHIC Energies

    SciTech Connect

    Nouicer, Rachid

    2006-07-11

    Charged particles produced in Cu+Cu collisions at {radical}(s{sub NN}) = 200 and 62.4 GeV have been measured in the PHOBOS experiment at RHIC. The comparison of the results for Cu+Cu and Au+Au for the most central collisions at the same energy reveals that the particle density per nucleon participant pair and the extended longitudinal scaling behavior are similar in both systems. This implies that for the most central events in symmetric nucleus-nucleus collisions the particle density per nucleon participant pair does not depend on the size of the two colliding nuclei but only on the collision energy. Also the extended longitudinal scaling seems independent of the colliding energy and species for central collisions. In addition, there is an overall factorization of dNch/d{eta} shapes as a function of collision centraliry between Au+Au and Cu+Cu collisions at the same energy.

  4. Charge-dependent azimuthal correlations from AuAu to UU collisions

    NASA Astrophysics Data System (ADS)

    Bloczynski, John; Huang, Xu-Guang; Zhang, Xilin; Liao, Jinfeng

    2015-07-01

    We study the charge-dependent azimuthal correlations in relativistic heavy ion collisions, as motivated by the search for the Chiral Magnetic Effect (CME) and the investigation of related background contributions. In particular we aim to understand how these correlations induced by various proposed effects evolve from collisions with AuAu system to that with UU system. To do that, we quantify the generation of magnetic field in UU collisions at RHIC energy and its azimuthal correlation with the matter geometry using event-by-event simulations. Taking the experimental data for charge-dependent azimuthal correlations from AuAu collisions and extrapolating to UU with reasonable assumptions, we examine the resulting correlations to be expected in UU collisions and compare them with recent STAR measurements. Based on such analysis we discuss the viability for explaining the data with a combination of the CME-like and flow-induced contributions.

  5. Some thoughts on di-jet correlation in Au + Au collisions from PHENIX

    SciTech Connect

    Jia Jiangyong

    2006-07-11

    PHENIX has measured the two particle azimuth correlation in Au + Au at {radical}(s) = 200 GeV. Jet shape and yield at the away side are found to be strongly modified at intermediate and low pT, and the modifications vary dramatically with pT and centrality. At high pT, away side jet peak reappears but the yield is suppressed. We discuss the possible physics pictures leading to these complicated modifications.

  6. Net charge fluctuations in Au + Au interactions at sqrt[s(NN)]=130 GeV.

    PubMed

    Adcox, K; Adler, S S; Ajitanand, N N; Akiba, Y; Alexander, J; Aphecetche, L; Arai, Y; Aronson, S H; Averbeck, R; Awes, T C; Barish, K N; Barnes, P D; Barrette, J; Bassalleck, B; Bathe, S; Baublis, V; Bazilevsky, A; Belikov, S; Bellaiche, F G; Belyaev, S T; Bennett, M J; Berdnikov, Y; Botelho, S; Brooks, M L; Brown, D S; Bruner, N; Bucher, D; Buesching, H; Bumazhnov, V; Bunce, G; Burward-Hoy, J; Butsyk, S; Carey, T A; Chand, P; Chang, J; Chang, W C; Chavez, L L; Chernichenko, S; Chi, C Y; Chiba, J; Chiu, M; Choudhury, R K; Christ, T; Chujo, T; Chung, M S; Chung, P; Cianciolo, V; Cole, B A; D'Enterria, D G; David, G; Delagrange, H; Denisov, A; Deshpande, A; Desmond, E J; Dietzsch, O; Dinesh, B V; Drees, A; Durum, A; Dutta, D; Ebisu, K; Efremenko, Y V; El Chenawi, K; En'yo, H; Esumi, S; Ewell, L; Ferdousi, T; Fields, D E; Fokin, S L; Fraenkel, Z; Franz, A; Frawley, A D; Fung, S-Y; Garpman, S; Ghosh, T K; Glenn, A; Godoi, A L; Goto, Y; Greene, S V; Grosse Perdekamp, M; Gupta, S K; Guryn, W; Gustafsson, H-A; Haggerty, J S; Hamagaki, H; Hansen, A G; Hara, H; Hartouni, E P; Hayano, R; Hayashi, N; He, X; Hemmick, T K; Heuser, J M; Hibino, M; Hill, J C; Ho, D S; Homma, K; Hong, B; Hoover, A; Ichihara, T; Imai, K; Ippolitov, M S; Ishihara, M; Jacak, B V; Jang, W Y; Jia, J; Johnson, B M; Johnson, S C; Joo, K S; Kametani, S; Kang, J H; Kann, M; Kapoor, S S; Kelly, S; Khachaturov, B; Khanzadeev, A; Kikuchi, J; Kim, D J; Kim, H J; Kim, S Y; Kim, Y G; Kinnison, W W; Kistenev, E; Kiyomichi, A; Klein-Boesing, C; Klinksiek, S; Kochenda, L; Kochetkov, V; Koehler, D; Kohama, T; Kotchetkov, D; Kozlov, A; Kroon, P J; Kurita, K; Kweon, M J; Kwon, Y; Kyle, G S; Lacey, R; Lajoie, J G; Lauret, J; Lebedev, A; Lee, D M; Leitch, M J; Li, X H; Li, Z; Lim, D J; Liu, M X; Liu, X; Liu, Z; Maguire, C F; Mahon, J; Makdisi, Y I; Manko, V I; Mao, Y; Mark, S K; Markacs, S; Martinez, G; Marx, M D; Masaike, A; Matathias, F; Matsumoto, T; McGaughey, P L; Melnikov, E; Merschmeyer, M; Messer, F; Messer, M; Miake, Y; Miller, T E; Milov, A; Mioduszewski, S; Mischke, R E; Mishra, G C; Mitchell, J T; Mohanty, A K; Morrison, D P; Moss, J M; Mühlbacher, F; Muniruzzaman, M; Murata, J; Nagamiya, S; Nagasaka, Y; Nagle, J L; Nakada, Y; Nandi, B K; Newby, J; Nikkinen, L; Nilsson, P; Nishimura, S; Nyanin, A S; Nystrand, J; O'Brien, E; Ogilvie, C A; Ohnishi, H; Ojha, I D; Ono, M; Onuchin, V; Oskarsson, A; Osterman, L; Otterlund, I; Oyama, K; Paffrath, L; Palounek, A P T; Pantuev, V S; Papavassiliou, V; Pate, S F; Peitzmann, T; Petridis, A N; Pinkenburg, C; Pisani, R P; Pitukhin, P; Plasil, F; Pollack, M; Pope, K; Purschke, M L; Ravinovich, I; Read, K F; Reygers, K; Riabov, V; Riabov, Y; Rosati, M; Rose, A A; Ryu, S S; Saito, N; Sakaguchi, A; Sakaguchi, T; Sako, H; Sakuma, T; Samsonov, V; Sangster, T C; Santo, R; Sato, H D; Sato, S; Sawada, S; Schlei, B R; Schutz, Y; Semenov, V; Seto, R; Shea, T K; Shein, I; Shibata, T-A; Shigaki, K; Shiina, T; Shin, Y H; Sibiriak, I G; Silvermyr, D; Sim, K S; Simon-Gillo, J; Singh, C P; Singh, V; Sivertz, M; Soldatov, A; Soltz, R A; Sorensen, S; Stankus, P W; Starinsky, N; Steinberg, P; Stenlund, E; Ster, A; Stoll, S P; Sugioka, M; Sugitate, T; Sullivan, J P; Sumi, Y; Sun, Z; Suzuki, M; Takagui, E M; Taketani, A; Tamai, M; Tanaka, K H; Tanaka, Y; Taniguchi, E; Tannenbaum, M J; Thomas, J; Thomas, J H; Thomas, T L; Tian, W; Tojo, J; Torii, H; Towell, R S; Tserruya, I; Tsuruoka, H; Tsvetkov, A A; Tuli, S K; Tydesjö, H; Tyurin, N; Ushiroda, T; van Hecke, H W; Velissaris, C; Velkovska, J; Velkovsky, M; Vinogradov, A A; Volkov, M A; Vorobyov, A; Vznuzdaev, E; Wang, H; Watanabe, Y; White, S N; Witzig, C; Wohn, F K; Woody, C L; Xie, W; Yagi, K; Yokkaichi, S; Young, G R; Yushmanov, I E; Zajc, W A; Zhang, Z; Zhou, S

    2002-08-19

    Data from Au + Au interactions at sqrt[s(NN)]=130 GeV, obtained with the PHENIX detector at the Relativistic Heavy-Ion Collider, are used to investigate local net charge fluctuations among particles produced near midrapidity. According to recent suggestions, such fluctuations may carry information from the quark-gluon plasma. This analysis shows that the fluctuations are dominated by a stochastic distribution of particles, but are also sensitive to other effects, like global charge conservation and resonance decays.

  7. Evidence of Significant Covalent Bonding in Au(CN)2-

    SciTech Connect

    Wang, Xue B.; wang, Yi-Lei; Yang, Jie; Xing, Xiaopeng; Li, Jun; Wang, Lai S.

    2009-11-18

    There have been intense recent interests in the homogeneous catalytic chemistry of Au(I) complexes.1 Among the Au(I) molecules, the Au(CN)2- ion is the most stable and has been widely used in gold extraction back to ancient times. Although AuCN in the condensed phase has been studied, including solution phase vibrational spectroscopy2 and crystal structures,3 the free AuCN molecule has been studied only very recently by microwave spectroscopy.4 The important Au(CN)2- complex has not been observed and studied in the gas phase. Because of the relativistic effects,5 Au-containing molecules exhibit distinctly different properties among the coinage elements. To elucidate the nature of the Au-ligand binding, high-level ab initio calculations are needed due to the complicated electron correlation and relativistic effects.6-8 The structure and bonding of the AuCN molecule were first examined computationally by Frenking and co-workers.7 Recent high-precision calculations by Pyykkö and co-workers suggest multiple-bond characters between Au-C in AuCN because the Au-C bond length is only slightly longer than the sum of the triple bond covalent radii.

  8. The effect of Au amount on size uniformity of self-assembled Au nanoparticles

    NASA Astrophysics Data System (ADS)

    Chen, S.-H.; Wang, D.-C.; Chen, G.-Y.; Chen, K.-Y.

    2008-03-01

    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 AuCl4- 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 AuCl4- 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 AuCl4- and thiol. The obtained nanoparticles could be used, for example, in uniform surface nanofabrication, leading to the fabrication of ordered array of quantum dots.

  9. Experimental and Theoretical Studies on Oxidation of Cu-Au Alloy Surfaces: Effect of Bulk Au Concentration.

    PubMed

    Okada, Michio; Tsuda, Yasutaka; Oka, Kohei; Kojima, Kazuki; Diño, Wilson Agerico; Yoshigoe, Akitaka; Kasai, Hideaki

    2016-01-01

    We report results of our experimental and theoretical studies on the oxidation of Cu-Au alloy surfaces, viz., Cu3Au(111), CuAu(111), and Au3Cu(111), using hyperthermal O2 molecular beam (HOMB). We observed strong Au segregation to the top layer of the corresponding clean (111) surfaces. This forms a protective layer that hinders further oxidation into the bulk. The higher the concentration of Au in the protective layer formed, the higher the protective efficacy. As a result, of the three Cu-Au surfaces studied, Au3Cu(111) is the most stable against dissociative adsorption of O2, even with HOMB. We also found that this protective property breaks down for oxidations occurring at temperatures above 300 K. PMID:27516137

  10. Bonding, Luminescence, Metallophilicity in Linear Au3 and Au2Ag Chains Stabilized by Rigid Diphosphanyl NHC Ligands.

    PubMed

    Ai, Pengfei; Mauro, Matteo; Gourlaouen, Christophe; Carrara, Serena; De Cola, Luisa; Tobon, Yeny; Giovanella, Umberto; Botta, Chiara; Danopoulos, Andreas A; Braunstein, Pierre

    2016-09-01

    The heterofunctional and rigid ligand N,N'-diphosphanyl-imidazol-2-ylidene (PCNHCP; P = P(t-Bu)2), through its phosphorus and two N-heterocyclic carbene (NHC) donors, stabilizes trinuclear chain complexes, with either Au3 or AgAu2 cores, and dinuclear Au2 complexes. The two oppositely situated PCNHCP (L) ligands that "sandwich" the metal chain can support linear and rigid structures, as found in the known tricationic Au(I) complex [Au3(μ3-PCNHCP,κP,κCNHC,κP)2](OTf)3 (OTf = CF3SO3; [Au3L2](OTf)3; Chem. Commun. 2014, 50, 103-105) now also obtained by transmetalation from [Ag3(μ3-PCNHCP,κP,κCNHC,κP)2](OTf)3 ([Ag3L2](OTf)3), or in the mixed-metal tricationic [Au2Ag(μ3-PCNHCP,κP,κCNHC,κP)2](OTf)3 ([Au2AgL2](OTf)3). The latter was obtained stepwise by the addition of AgOTf to the digold(I) complex [Au2(μ2-PCNHCP,κP,κCNHC)2](OTf)2 ([Au2L2](OTf)2). The latter contains two dangling P donors and displays fluxional behavior in solution, and the Au···Au separation of 2.8320(6) Å in the solid state is consistent with metallophilic interactions. In the solvento complex [Au3Cl2(tht)(μ3-PCNHCP,κP,κCNHC,κP)](OTf)·MeCN ([Au3Cl2(tht)L](OTf)·MeCN), which contains only one L and one tht ligand (tht = tetrahydrothiophene), the metal chain is bent (148.94(2)°), and the longer Au···Au separation (2.9710(4) Å) is in line with relaxation of the rigidity due to a more "open" structure. Similar features were observed in [Au3Cl2(SMe2)L](OTf)·2MeCN. A detailed study of the emission properties of [Au3L2](OTf)3, [Au3Cl2(tht)L](OTf)·MeCN, [Au2L2](OTf)2, and [Au2AgL2](OTf)3 was performed by means of steady state and time-resolved photophysical techniques. The complex [Au3L2](OTf)3 displays a bright (photoluminescence quantum yield = 80%) and narrow emission band centered at 446 nm with a relatively small Stokes' shift and long-lived excited-state lifetime on the microsecond timescale, both in solution and in the solid state. In line with the very narrow emission

  11. Identified particle distributions in pp and Au+Au collisions atsqrt sNN=200 GeV

    SciTech Connect

    Adams, J.; Adler, C.; Aggarwal, M.M.; Ahammed, Z.; Amonett, J.; Anderson, B.D.; Anderson, M; Arkhipkin, D.; Averichev, G.S.; Badyal,S.K.; Balewski, J.; Barannikova, O.; Barnby, L.S.; Baudot, J.; Bekele,S.; Belaga, V.V.; Bellwied, R.; Berger, J.; Bezverkhny, B.I.; Bhardwaj,S.; Bhaskar, P.; Bhati, A.K.; Bichsel, H.; Billmeier, A.; Bland, L.C.; Blyth, C.O.; Bonner, B.E.; Botje, M.; Boucham, A.; Brandin, A.; Bravar,A.; Cadman, R.V.; Cai, X.Z.; Caines, H.; Calderon de la Barca Sanchez,M.; Carroll, J.; Castillo, J.; Castro, M.; Cebra, D.; Chaloupka, P.; Chattopadhyay, S.; Chen, H.F.; Chen, Y.; Chernenko, S.P.; Cherney, M.; Chikanian, A.; Choi, B.; Christie, W.; Coffin, J.P.; Cormier, T.M.; Cramer, J.G.; Crawford, H.J.; Das, D.; Das, S.; Derevschikov, A.A.; Didenko, L.; Dietel, T.; Dong, X.; Draper, J.E.; Du, F.; Dubey, A.K.; Dunin, V.B.; Dunlop, J.C.; Dutta Majumdar, M.R.; Eckardt, V.; Efimov,L.G.; Emelianov, V.; Engelage, J.; Eppley, G.; Erazmus, B.; Estienne, M.; Fachini, P.; Faine, V.; Faivre, J.; Fatemi, R.; Filimonov, K.; Filip, P.; Finch, E.; Fisyak, Y.; Flierl, D.; Foley, K.J.; Fu, J.; Gagliardi, C.A.; Ganti, M.S.; Gutierrez, T.D.; Gagunashvili, N.; Gans, J.; Gaudichet, L.; Germain, M.; Geurts, F.; Ghazikhanian, V.; Ghosh, P.; Gonzalez, J.E.; Grachov, O.; Grigoriev, V.; Cronstal, S.; Grosnick, D.; Guedon, M.; Guertin, S.M.; Gupta, A.; Gushin, E.; Hallman, T.J.; Hardtke, D.; Harris,J.W.; Heinz, M.; Henry, T.W.; Heppelmann, S.; Herston, T.; Hippolyte, B.; Hirsch, A.; Hjort, E.; Hoffmann, G.W.; Horsley, M.; Huang, H.Z.; Huang,S.L.; Humanic, T.J.; Igo, G.; Ishihara, A.; Jacobs, P.; Jacobs, W.W.; Janik, M.; Johnson, I.; Jones, P.G.; Judd, E.G.; Kabana, S.; Kaneta, M.; Kaplan, M.; Keane, D.; Kiryluk, J.; Kisiel, A.; Klay, J.; Klein, S.R.; Klyachko, A.; Koetke, D.D.; Kollegger, T.; Konstantinov, A.S.; Kopytine,S.M.; Kotchenda, L.; Kovalenko, A.D.; Kramer, M.; Kravtsov, P.; Krueger,K.; Kuhn, C.; Kulikov, A.I.; Kumar, A.; et al.

    2003-10-06

    Transverse mass and rapidity distributions for charged pions, charged kaons, protons and antiprotons are reported for {radical}sNN = 200 GeV pp and Au+Au collisions at RHIC. The transverse mass distributions are rapidity independent within |y| < 0.5, consistent with a boost-invariant system in this rapidity interval. Spectral shapes and relative particle yields are similar in pp and peripheral Au+Au collisions and change smoothly to central Au+Au collisions. No centrality dependence was observed in the kaon and antiproton production rates relative to the pion production rate from medium-central to central collisions. Chemical and kinetic equilibrium model fits to our data reveal strong radial flow and relatively long duration from chemical to kinetic freeze-out in central Au+Au collisions. The chemical freeze-out temperature appears to be independent of initial conditions at RHIC energies.

  12. Experimental and Theoretical Studies on Oxidation of Cu-Au Alloy Surfaces: Effect of Bulk Au Concentration

    PubMed Central

    Okada, Michio; Tsuda, Yasutaka; Oka, Kohei; Kojima, Kazuki; Diño, Wilson Agerico; Yoshigoe, Akitaka; Kasai, Hideaki

    2016-01-01

    We report results of our experimental and theoretical studies on the oxidation of Cu-Au alloy surfaces, viz., Cu3Au(111), CuAu(111), and Au3Cu(111), using hyperthermal O2 molecular beam (HOMB). We observed strong Au segregation to the top layer of the corresponding clean (111) surfaces. This forms a protective layer that hinders further oxidation into the bulk. The higher the concentration of Au in the protective layer formed, the higher the protective efficacy. As a result, of the three Cu-Au surfaces studied, Au3Cu(111) is the most stable against dissociative adsorption of O2, even with HOMB. We also found that this protective property breaks down for oxidations occurring at temperatures above 300 K. PMID:27516137

  13. Bonding, Luminescence, Metallophilicity in Linear Au3 and Au2Ag Chains Stabilized by Rigid Diphosphanyl NHC Ligands.

    PubMed

    Ai, Pengfei; Mauro, Matteo; Gourlaouen, Christophe; Carrara, Serena; De Cola, Luisa; Tobon, Yeny; Giovanella, Umberto; Botta, Chiara; Danopoulos, Andreas A; Braunstein, Pierre

    2016-09-01

    The heterofunctional and rigid ligand N,N'-diphosphanyl-imidazol-2-ylidene (PCNHCP; P = P(t-Bu)2), through its phosphorus and two N-heterocyclic carbene (NHC) donors, stabilizes trinuclear chain complexes, with either Au3 or AgAu2 cores, and dinuclear Au2 complexes. The two oppositely situated PCNHCP (L) ligands that "sandwich" the metal chain can support linear and rigid structures, as found in the known tricationic Au(I) complex [Au3(μ3-PCNHCP,κP,κCNHC,κP)2](OTf)3 (OTf = CF3SO3; [Au3L2](OTf)3; Chem. Commun. 2014, 50, 103-105) now also obtained by transmetalation from [Ag3(μ3-PCNHCP,κP,κCNHC,κP)2](OTf)3 ([Ag3L2](OTf)3), or in the mixed-metal tricationic [Au2Ag(μ3-PCNHCP,κP,κCNHC,κP)2](OTf)3 ([Au2AgL2](OTf)3). The latter was obtained stepwise by the addition of AgOTf to the digold(I) complex [Au2(μ2-PCNHCP,κP,κCNHC)2](OTf)2 ([Au2L2](OTf)2). The latter contains two dangling P donors and displays fluxional behavior in solution, and the Au···Au separation of 2.8320(6) Å in the solid state is consistent with metallophilic interactions. In the solvento complex [Au3Cl2(tht)(μ3-PCNHCP,κP,κCNHC,κP)](OTf)·MeCN ([Au3Cl2(tht)L](OTf)·MeCN), which contains only one L and one tht ligand (tht = tetrahydrothiophene), the metal chain is bent (148.94(2)°), and the longer Au···Au separation (2.9710(4) Å) is in line with relaxation of the rigidity due to a more "open" structure. Similar features were observed in [Au3Cl2(SMe2)L](OTf)·2MeCN. A detailed study of the emission properties of [Au3L2](OTf)3, [Au3Cl2(tht)L](OTf)·MeCN, [Au2L2](OTf)2, and [Au2AgL2](OTf)3 was performed by means of steady state and time-resolved photophysical techniques. The complex [Au3L2](OTf)3 displays a bright (photoluminescence quantum yield = 80%) and narrow emission band centered at 446 nm with a relatively small Stokes' shift and long-lived excited-state lifetime on the microsecond timescale, both in solution and in the solid state. In line with the very narrow emission

  14. Centrality dependence of direct photon production in (square root)S(NN) = 200 GeV Au + Au collisions.

    PubMed

    Adler, S S; Afanasiev, S; Aidala, C; Ajitanand, N N; Akiba, Y; Alexander, J; Amirikas, R; Aphecetche, L; Aronson, S H; Averbeck, R; Awes, T C; Azmoun, R; Babintsev, V; Baldisseri, A; Barish, K N; Barnes, P D; Bassalleck, B; Bathe, S; Batsouli, S; Baublis, V; Bazilevsky, A; Belikov, S; Berdnikov, Y; Bhagavatula, S; Boissevain, J G; Borel, H; Borenstein, S; Brooks, M L; Brown, D S; Bruner, N; Bucher, D; Buesching, H; Bumazhnov, V; Bunce, G; Burward-Hoy, J M; Butsyk, S; Camard, X; Chai, J-S; Chand, P; Chang, W C; Chernichenko, S; Chi, C Y; Chiba, J; Chiu, M; Choi, I J; Choi, J; Choudhury, R K; Chujo, T; Cianciolo, V; Cobigo, Y; Cole, B A; Constantin, P; d'Enterria, D; David, G; Delagrange, H; Denisov, A; Deshpande, A; Desmond, E J; Devismes, A; Dietzsch, O; Drapier, O; Drees, A; du Rietz, R; Durum, A; Dutta, D; Efremenko, Y V; El Chenawi, K; Enokizono, A; En'yo, H; Esumi, S; Ewell, L; Fields, D E; Fleuret, F; Fokin, S L; Fox, B D; Fraenkel, Z; Frantz, J E; Franz, A; Frawley, A D; Fung, S-Y; Garpman, S; Ghosh, T K; Glenn, A; Gogiberidze, G; Gonin, M; Gosset, J; Goto, Y; Granier de Cassagnac, R; Grau, N; Greene, S V; Perdekamp, M Grosse; Guryn, W; Gustafsson, H-A; Hachiya, T; Haggerty, J S; Hamagaki, H; Hansen, A G; Hartouni, E P; Harvey, M; Hayano, R; Hayashi, N; He, X; Heffner, M; Hemmick, T K; Heuser, J M; Hibino, M; Hill, J C; Holzmann, W; Homma, K; Hong, B; Hoover, A; Ichihara, T; Ikonnikov, V V; Imai, K; Isenhower, D; Ishihara, M; Issah, M; Isupov, A; Jacak, B V; Jang, W Y; Jeong, Y; Jia, J; Jinnouchi, O; Johnson, B M; Johnson, S C; Joo, K S; Jouan, D; Kametani, S; Kamihara, N; Kang, J H; Kapoor, S S; Katou, K; Kelly, S; Khachaturov, B; Khanzadeev, A; Kikuchi, J; Kim, D H; Kim, D J; Kim, D W; Kim, E; Kim, G-B; Kim, H J; Kistenev, E; Kiyomichi, A; Kiyoyama, K; Klein-Boesing, C; Kobayashi, H; Kochenda, L; Kochetkov, V; Koehler, D; Kohama, T; Kopytine, M; Kotchetkov, D; Kozlov, A; Kroon, P J; Kuberg, C H; Kurita, K; Kuroki, Y; Kweon, M J; Kwon, Y; Kyle, G S; Lacey, R; Ladygin, V; Lajoie, J G; Lebedev, A; Leckey, S; Lee, D M; Lee, S; Leitch, M J; Li, X H; Lim, H; Litvinenko, A; Liu, M X; Liu, Y; Maguire, C F; Makdisi, Y I; Malakhov, A; Manko, V I; Mao, Y; Martinez, G; Marx, M D; Masui, H; Matathias, F; Matsumoto, T; McGaughey, P L; Melnikov, E; Messer, F; Miake, Y; Milan, J; Miller, T E; Milov, A; Mioduszewski, S; Mischke, R E; Mishra, G C; Mitchell, J T; Mohanty, A K; Morrison, D P; Moss, J M; Mühlbacher, F; Mukhopadhyay, D; Muniruzzaman, M; Murata, J; Nagamiya, S; Nagle, J L; Nakamura, T; Nandi, B K; Nara, M; Newby, J; Nilsson, P; Nyanin, A S; Nystrand, J; O'Brien, E; Ogilvie, C A; Ohnishi, H; Ojha, I D; Okada, K; Ono, M; Onuchin, V; Oskarsson, A; Otterlund, I; Oyama, K; Ozawa, K; Pal, D; Palounek, A P T; Pantuev, V; Papavassiliou, V; Park, J; Parmar, A; Pate, S F; Peitzmann, T; Peng, J-C; Peresedov, V; Pinkenburg, C; Pisani, R P; Plasil, F; Purschke, M L; Purwar, A K; Rak, J; Ravinovich, I; Read, K F; Reuter, M; Reygers, K; Riabov, V; Riabov, Y; Roche, G; Romana, A; Rosati, M; Rosnet, P; Ryu, S S; Sadler, M E; Saito, N; Sakaguchi, T; Sakai, M; Sakai, S; Samsonov, V; Sanfratello, L; Santo, R; Sato, H D; Sato, S; Sawada, S; Schutz, Y; Semenov, V; Seto, R; Shaw, M R; Shea, T K; Shibata, T-A; Shigaki, K; Shiina, T; Silva, C L; Silvermyr, D; Sim, K S; Singh, C P; Singh, V; Sivertz, M; Soldatov, A; Soltz, R A; Sondheim, W E; Sorensen, S P; Sourikova, I V; Staley, F; Stankus, P W; Stenlund, E; Stepanov, M; Ster, A; Stoll, S P; Sugitate, T; Sullivan, J P; Takagui, E M; Taketani, A; Tamai, M; Tanaka, K H; Tanaka, Y; Tanida, K; Tannenbaum, M J; Tarján, P; Tepe, J D; Thomas, T L; Tojo, J; Torii, H; Towell, R S; Tserruya, I; Tsuruoka, H; Tuli, S K; Tydesjö, H; Tyurin, N; van Hecke, H W; Velkovska, J; Velkovsky, M; Veszprémi, V; Villatte, L; Vinogradov, A A; Volkov, M A; Vznuzdaev, E; Wang, X R; Watanabe, Y; White, S N; Wohn, F K; Woody, C L; Xie, W; Yang, Y; Yanovich, A; Yokkaichi, S; Young, G R; Yushmanov, I E; Zajc, W A; Zhang, C; Zhou, S; Zhou, S J; Zolin, L

    2005-06-17

    The first measurement of direct photons in Au + Au collisions at (square root)S(NN) = 200 GeV is presented. The direct photon signal is extracted as a function of the Au + Au collision centrality and compared to next-to-leading order perturbative quantum chromodynamics calculations. The direct photon yield is shown to scale with the number of nucleon-nucleon collisions for all centralities.

  15. Slab melting and the origin of gold in Au and Au-Cu deposits: geochemical clues from recent adakites.

    NASA Astrophysics Data System (ADS)

    Polve, M.; Maury, R.; Joron, J. L.

    2003-04-01

    Understanding the genetic processes responsible for the common occurrence of Au and Au-Cu deposits in subduction environments is a fairly "hot" question nowadays, as it is clear that most subduction-related magmatic rocks are barren. Studies of space and time relationships between magmatic intrusions, hydrothermal episodes and Au deposits have shown that, very often, Au deposits are associated with adakitic intrusions (Thieblemont et al, 1997, Sajona and Maury, 1998). Adakites are here understood as being generated by melting of the subducting oceanic crust. This study aims to check wether or not magmas derived from melted oceanic crust do contain significantly more Au than regular calc-alkaline magmas by measuring directly Au concentrations in fresh (and barren) adakites and equivalent calc-alkaline andesites. There is a lack of reliable data on Au content in unaltered adakites and andesites, because Au analyses are generally done on hydrothermalized rocks in connection with Au deposits and also because old measurements may give overestimated Au contents, due to technical limitations. Therefore we compiled recent literature data on gold contents of fresh calc-alkaline rocks, and measured Au on a selection of 40 well studied and dated adakites from different localities (Philippines, Baja California). Analyses have been performed either by INAA or by ICP-MS after Au extraction with aqua regia, following the method described by Terashima (1988). Preliminary results show that, for equivalent Si02 contents, adakites are systematically enriched in Au compared to regular dacites, even if regional trends also exist. Moreover, Au seems to behave as an incompatible element in adakitic magmas, whereas in calc-alkaline dacites it is controlled by sulfide crystallization. Our data suggest that, not excluding any other processes related to the hydrothermal phase in the deposit generation, adakites may indeed represent the source of Au, a possible explanation for the adakite-Au

  16. AU-FREDI - AUTONOMOUS FREQUENCY DOMAIN IDENTIFICATION

    NASA Technical Reports Server (NTRS)

    Yam, Y.

    1994-01-01

    The Autonomous Frequency Domain Identification program, AU-FREDI, is a system of methods, algorithms and software that was developed for the identification of structural dynamic parameters and system transfer function characterization for control of large space platforms and flexible spacecraft. It was validated in the CALTECH/Jet Propulsion Laboratory's Large Spacecraft Control Laboratory. Due to the unique characteristics of this laboratory environment, and the environment-specific nature of many of the software's routines, AU-FREDI should be considered to be a collection of routines which can be modified and reassembled to suit system identification and control experiments on large flexible structures. The AU-FREDI software was originally designed to command plant excitation and handle subsequent input/output data transfer, and to conduct system identification based on the I/O data. Key features of the AU-FREDI methodology are as follows: 1. AU-FREDI has on-line digital filter design to support on-orbit optimal input design and data composition. 2. Data composition of experimental data in overlapping frequency bands overcomes finite actuator power constraints. 3. Recursive least squares sine-dwell estimation accurately handles digitized sinusoids and low frequency modes. 4. The system also includes automated estimation of model order using a product moment matrix. 5. A sample-data transfer function parametrization supports digital control design. 6. Minimum variance estimation is assured with a curve fitting algorithm with iterative reweighting. 7. Robust root solvers accurately factorize high order polynomials to determine frequency and damping estimates. 8. Output error characterization of model additive uncertainty supports robustness analysis. The research objectives associated with AU-FREDI were particularly useful in focusing the identification methodology for realistic on-orbit testing conditions. Rather than estimating the entire structure, as is

  17. Climatology of Vertical Ion Velocity and its Relationship with Large-scale FAC Based on DMSP and CHAMP Observations: Seasonal and IMF By Dependence

    NASA Astrophysics Data System (ADS)

    Luhr, H.; Kervalishvili, G.

    2015-12-01

    In this study we present climatology of vertical ion drift and its relationship with large-scale field-aligned current (LSFAC) in the Northern Hemisphere cusp region using the superposed epoch analysis (SEA) method. The dependence on the interplanetary magnetic field (IMF) Bycomponent orientation and the local season is also investigated. The three local seasons of 130 days each are defined as follows: local winter (1 January ± 65 days), combined equinoxes (1 April and 1 October ± 32 days), and local summer (1 July ± 65 days). Our results are based on DMSP (F13 and F15) and CHAMP satellite observations and NASA/GSFC's OMNI online data set during the years 2001-2005. The time and location of the vertical ion velocity peaks (> 100 m/s for upflow and <-100 m/s for downflow) in the cusp region are used as reference parameters (time and location of the event) for the SEA method. Event number distribution based on the ion velocity peaks shows no significant variations for IMF By component orientation and local season. Corresponding averaged profiles of total magnetic field Bt and IMF components, taken for flow events from both DMSP satellites and all seasons together, also show no differences in temporal variations (only negligible changes in amplitude) between upflow and downflow events. There is no systematic sign change related to flow direction in any of the three IMF components and IMF Bz is always negative. IMF By and Bz components are peaking about half an hour before the event for all considered cases. The main findings of our SEA analysis, can be summarized as follows: Vertical plasma flow, taken for both DMSP satellites together, shows no dependence on IMF By component orientation. Its amplitude is increasing towards local summer. Vertical plasma velocity is much higher in winter than during combined equinox or summer. It seems the ion density is low in winter and increases towards local summer. The plasma upflow is generally stronger than the downflow in

  18. The intensity of physical activity influences bone mineral accrual in childhood: the childhood health, activity and motor performance school (the CHAMPS) study, Denmark

    PubMed Central

    2013-01-01

    Background Studies indicate genetic and lifestyle factors can contribute to optimal bone development. In particular, the intensity level of physical activity may have an impact on bone health. This study aims to assess the relationship between physical activity at different intensities and Bone Mineral Content (BMC), Bone Mineral Density (BMD) and Bone Area (BA) accretion. Methods This longitudinal study is a part of The CHAMPS study-DK. Whole-body DXA scans were performed at baseline and after two years follows up. BMC, BMD, and BA were measured. The total body less head (TBLH) values were used. Physical activity (PA) was recorded by accelerometers (ActiGraph, model GT3X). Percentages of different PA intensity levels were calculated and log odds of two intensity levels of activity relative to the third level were calculated. Multilevel regression analyses were used to assess the relationship between the categories of physical activity and bone traits. Results Of 800 invited children, 742 (93%) accepted to participate. Of these, 682/742 (92%) participated at follow up. Complete datasets were obtained in 602/742 (81%) children. Mean (range) of age was 11.5 years (9.7-13.9). PA at different intensity levels was for boys and girls respectively, sedentary 62% and 64%, low 29% for both genders and moderate to high 9% and 7% of the total time. Mean (range) BMC, BMD, and BA was 1179 g (563–2326), 0.84 g/cm2 (0.64-1.15) and 1393 cm2 (851–2164), respectively. Valid accelerometer data were obtained for a mean of 6.1 days, 13 hours per day. Conclusions There 7was a positive relationship between the log odds of moderate to high-level PA versus low level activity and BMC, BMD and BA. Children with an increased proportion of time in moderate to high-level activity as opposed to sedentary and low-level activity achieved positive effects on BMC, BMD and BA. PMID:23452342

  19. Di-hadron correlations with identified leading hadrons in 200 GeV Au + Au and d + Au collisions at STAR

    NASA Astrophysics Data System (ADS)

    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.

  20. From the ternary Eu(Au/In)2 and EuAu4(Au/In)2 with remarkable Au/In distributions to a new structure type: The gold-rich Eu5Au16(Au/In)6 structure

    DOE PAGESBeta

    Steinberg, Simon; Card, Nathan; Mudring, Anja -Verena

    2015-08-13

    The ternary Eu(Au/In)2 (EuAu0.46In1.54(2)) (I), EuAu4(Au/In)2 (EuAu4+xIn2–x with x = 0.75(2) (II), 0.93(2), and 1.03(2)), and Eu5Au16(Au/In)6 (Eu5Au17.29In4.71(3)) (III) have been synthesized, and their structures were characterized by single-crystal X-ray diffraction. I and II crystallize with the CeCu2-type (Pearson Symbol oI12; Imma; Z = 4; a = 4.9018(4) Å; b = 7.8237(5) Å; c = 8.4457(5) Å) and the YbAl4Mo2-type (tI14; I4/mmm; Z = 2; a = 7.1612(7) Å; c = 5.5268(7) Å) and exhibit significant Au/In disorder. I is composed of an Au/In-mixed diamond-related host lattice encapsulating Eu atoms, while the structure of II features ribbons of distorted, squaredmore » Au8 prisms enclosing Eu, Au, and In atoms. Combination of these structural motifs leads to a new structure type as observed for Eu5Au16(Au/In)6 (Eu5Au17.29In4.71(3)) (oS108; Cmcm; Z = 4; a = 7.2283(4) Å; b = 9.0499(6) Å; c = 34.619(2) Å), which formally represents a one-dimensional intergrowth of the series EuAu2–“EuAu4In2”. The site preferences of the disordered Au/In positions in II were investigated for different hypothetical “EuAu4(Au/In)2” models using the projector-augmented wave method and indicate that these structures attempt to optimize the frequencies of the heteroatomic Au–In contacts. Furthermore, a chemical bonding analysis on two “EuAu5In” and “EuAu4In2” models employed the TB-LMTO-ASA method and reveals that the subtle interplay between the local atomic environments and the bond energies determines the structural and site preferences for these systems.« less

  1. Fe impurities weaken the ferromagnetic behavior in Au nanoparticles.

    PubMed

    Crespo, P; García, M A; Fernández Pinel, E; Multigner, M; Alcántara, D; de la Fuente, J M; Penadés, S; Hernando, A

    2006-10-27

    In this Letter, we report on a crucial experiment showing that magnetic impurities reduce the ferromagnetic order temperature in thiol-capped Au glyconanoparticles (GNPs). The spontaneous magnetization of AuFe GNPs exhibits a fast decrease with temperature that contrasts with the almost constant value of the magnetization observed in Au NPs. Moreover, hysteresis disappears below 300 K. Both features indicate that Fe impurities reduce the high local anisotropy field responsible for the ferromagnetic behavior in Au GNPs. As a consequence, the amazing ferromagnetism in Au NPs should not be associated with the presence of magnetic impurities.

  2. Enhanced spin pumping at yttrium iron garnet/Au interfaces

    SciTech Connect

    Burrowes, C.; Heinrich, B.; Kardasz, B.; Montoya, E. A.; Girt, E.; Sun Yiyan; Song, Young-Yeal; Wu Mingzhong

    2012-02-27

    Spin injection across the ferrimagnetic insulator yttrium iron garnet (YIG)/normal metal Au interface was studied using ferromagnetic resonance. The spin mixing conductance was determined by comparing the Gilbert damping parameter {alpha} in YIG/Au and YIG/Au/Fe heterostructures. The main purpose of this study was to correlate the spin pumping efficiency with chemical modifications of the YIG film surface using in situ etching and deposition techniques. By means of Ar{sup +} ion beam etching, one is able to increase the spin mixing conductance at the YIG/Au interface by a factor of 5 compared to the untreated YIG/Au interface.

  3. Synthesis, structure, and bonding in K12Au21Sn4. A polar intermetallic compound with dense Au20 and open AuSn4 layers

    SciTech Connect

    Li, Bin; Kim, Sung-Jin; Miller, Gordon J.; and Corbett, John D.

    2009-10-29

    The new phase K{sub 12}Au{sub 21}Sn{sub 4} has been synthesized by direct reaction of the elements at elevated temperatures. Single crystal X-ray diffraction established its orthorhombic structure, space group Pmmn (No. 59), a = 12.162(2); b = 18.058(4); c = 8.657(2) {angstrom}, V = 1901.3(7) {angstrom}{sup 3}, and Z = 2. The structure consists of infinite puckered sheets of vertex-sharing gold tetrahedra (Au{sub 20}) that are tied together by thin layers of alternating four-bonded-Sn and -Au atoms (AuSn{sub 4}). Remarkably, the dense but electron-poorer blocks of Au tetrahedra coexist with more open and saturated Au-Sn layers, which are fragments of a zinc blende type structure that maximize tetrahedral heteroatomic bonding outside of the network of gold tetrahedra. LMTO band structure calculations reveal metallic properties and a pseudogap at 256 valence electrons per formula unit, only three electrons fewer than in the title compound and at a point at which strong Au-Sn bonding is optimized. Additionally, the tight coordination of the Au framework atoms by K plays an important bonding role: each Au tetrahedra has 10 K neighbors and each K atom has 8-12 Au contacts. The appreciably different role of the p element Sn in this structure from that in the triel members in K{sub 3}Au{sub 5}In and Rb{sub 2}Au{sub 3}Tl appears to arise from its higher electron count which leads to better p-bonding (valence electron concentrations = 1.32 versus 1.22).

  4. Isomorphism and solid solutions among Ag- and Au-selenides

    NASA Astrophysics Data System (ADS)

    Palyanova, Galina A.; Seryotkin, Yurii V.; Kokh, Konstantin A.; Bakakin, Vladimir V.

    2016-09-01

    Au-Ag selenides were synthesized by heating stoichiometric mixtures of elementary substances of initial compositions Ag2-xAuxSe with a step of x=0.25 (0≤x≤2) to 1050 °C and annealing at 500 °C. Scanning electron microscopy, optical microscopy, electron microprobe analysis and X-ray powder diffraction methods have been applied to study synthesized samples. Results of studies of synthesized products revealed the existence of three solid solutions with limited isomorphism Ag↔Au: naumannite Ag2Se - Ag1.94Au0.06Se, fischesserite Ag3AuSe2 - Ag3.2Au0.8Se2 and gold selenide AuSe - Au0.94Ag0.06Se. Solid solutions and AgAuSe phases were added to the phase diagram of Ag-Au-Se system. Crystal-chemical interpretation of Ag-Au isomorphism in selenides was made on the basis of structural features of fischesserite, naumannite, and AuSe.

  5. Bactericidal mechanisms of Au@TNBs under visible light irradiation.

    PubMed

    Guo, Lingqiao; Shan, Chao; Liang, Jialiang; Ni, Jinren; Tong, Meiping

    2015-04-01

    Au@TNBs nanocomposites were synthesized by depositing Au nanoparticles onto the surfaces of TiO2 nanobelts (TNBs). The disinfection activities of Au@TNBs on model cell type, Gram-negative Escherichia coli (E. coli), were examined under visible light irradiation conditions. Au@TNBs exhibited stronger bactericidal properties toward E. coli than those of TNBs and Au NPs under visible light irradiation. The bactericidal mechanisms of Au@TNBs under light conditions were explored, specifically, the specific active species controlling the inactivation of bacteria were determined. Active species (H2O2, diffusing ∙OH, ∙O2-, 1O2, and e-) generated by Au@TNBs were found to play important roles on the inactivation of bacteria. Moreover, the concentrations of H2O2, ·OH, ·O2-, and 1O2 generated in the antimicrobial system were estimated. Without the presence of active species, the direct contact of Au@TNBs with bacterial cells was found to have no bactericidal effect. The reusability of Au@TNBs were also determined. Au@TNBs exhibited strong antibacterial activity toward E. coli even in five consecutively reused cycles. This study indicated that the fabricated Au@TNBs could be potentially utilized to inactivate bacteria in water.

  6. Monolithic Nanocrystalline Au Fabricated by the Compaction of Nanoscale Foam

    SciTech Connect

    Hodge, A M; Biener, J; Hsiung, L M; Hamza, A V; Satcher Jr., J H

    2004-07-28

    We describe a two-step dealloying/compaction process to produce nanocrystalline Au. First, nanocrystalline/nanoporous Au foam is synthesized by electrochemically-driven dealloying. The resulting Au foams exhibit porosities of 60 and 70% with pore sizes of {approx} 40 and 100 nm, respectively, and a typical grain size of <50 nm. Second, the nanoporous foams are fully compacted to produce nanocrystalline monolithic Au. The compacted Au was characterized by TEM and X-ray diffraction and tested by depth-sensing nanoindentation. The compacted nanocrystalline Au exhibits an average grain size of <50 nm and hardness values ranging from 1.4 to 2.0 GPa, which are up to 4.5 times higher than the hardness values obtained from polycrystalline Au.

  7. Au-nanoparticles grafted on plasma treated PE

    NASA Astrophysics Data System (ADS)

    Švorčík, V.; Chaloupka, A.; Řezanka, P.; Slepička, P.; Kolská, Z.; Kasálková, N.; Hubáček, T.; Siegel, J.

    2010-03-01

    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.

  8. Collision-spike sputtering of Au nanoparticles

    SciTech Connect

    Sandoval, Luis; Urbassek, Herbert M.

    2015-08-06

    Ion irradiation of nanoparticles leads to enhanced sputter yields if the nanoparticle size is of the order of the ion penetration depth. While this feature is reasonably well understood for collision-cascade sputtering, we explore it in the regime of collision-spike sputtering using molecular-dynamics simulation. For this specific case of 200-keV Xe bombardment of Au particles, we show that collision spikes lead to abundant sputtering with an average yield of 397 ± 121 atoms compared to only 116 ± 48 atoms for a bulk Au target. Only around 31% of the impact energy remains in the nanoparticles after impact; the remainder is transported away by the transmitted projectile and the ejecta. The sputter yield of supported nanoparticles is estimated to be around 80% of that of free nanoparticles due to the suppression of forward sputtering.

  9. Collision-spike sputtering of Au nanoparticles

    DOE PAGESBeta

    Sandoval, Luis; Urbassek, Herbert M.

    2015-08-06

    Ion irradiation of nanoparticles leads to enhanced sputter yields if the nanoparticle size is of the order of the ion penetration depth. While this feature is reasonably well understood for collision-cascade sputtering, we explore it in the regime of collision-spike sputtering using molecular-dynamics simulation. For this specific case of 200-keV Xe bombardment of Au particles, we show that collision spikes lead to abundant sputtering with an average yield of 397 ± 121 atoms compared to only 116 ± 48 atoms for a bulk Au target. Only around 31% of the impact energy remains in the nanoparticles after impact; the remaindermore » is transported away by the transmitted projectile and the ejecta. The sputter yield of supported nanoparticles is estimated to be around 80% of that of free nanoparticles due to the suppression of forward sputtering.« less

  10. Collision-spike Sputtering of Au Nanoparticles.

    PubMed

    Sandoval, Luis; Urbassek, Herbert M

    2015-12-01

    Ion irradiation of nanoparticles leads to enhanced sputter yields if the nanoparticle size is of the order of the ion penetration depth. While this feature is reasonably well understood for collision-cascade sputtering, we explore it in the regime of collision-spike sputtering using molecular-dynamics simulation. For the particular case of 200-keV Xe bombardment of Au particles, we show that collision spikes lead to abundant sputtering with an average yield of 397 ± 121 atoms compared to only 116 ± 48 atoms for a bulk Au target. Only around 31 % of the impact energy remains in the nanoparticles after impact; the remainder is transported away by the transmitted projectile and the ejecta. The sputter yield of supported nanoparticles is estimated to be around 80 % of that of free nanoparticles due to the suppression of forward sputtering.

  11. Tunable VO2/Au hyperbolic metamaterial

    NASA Astrophysics Data System (ADS)

    Prayakarao, S.; Mendoza, B.; Devine, A.; Kyaw, C.; van Dover, R. B.; Liberman, V.; Noginov, M. A.

    2016-08-01

    Vanadium dioxide (VO2) is known to have a semiconductor-to-metal phase transition at ˜68 °C. Therefore, it can be used as a tunable component of an active metamaterial. The lamellar metamaterial studied in this work is composed of subwavelength VO2 and Au layers and is designed to undergo a temperature controlled transition from the optical hyperbolic phase to the metallic phase. VO2 films and VO2/Au lamellar metamaterial stacks have been fabricated and studied in electrical conductivity and optical (transmission and reflection) experiments. The observed temperature-dependent changes in the reflection and transmission spectra of the metamaterials and VO2 thin films are in a good qualitative agreement with theoretical predictions. The demonstrated optical hyperbolic-to-metallic phase transition is a unique physical phenomenon with the potential to enable advanced control of light-matter interactions.

  12. Fabrication of a chitosan/glucose oxidase-poly(anilineboronic acid)-Au(nano)/Au-plated Au electrode for biosensor and biofuel cell.

    PubMed

    Huang, Yi; Qin, Xiaoli; Li, Zou; Fu, Yingchun; Qin, Cong; Wu, Feng; Su, Zhaohong; Ma, Ming; Xie, Qingji; Yao, Shouzhuo; Hu, Jiming

    2012-01-15

    Enzyme immobilization is one of the key factors in constructing high-performance enzyme biosensors and biofuel cells (BFCs). Herein, we propose a new protocol for efficient immobilization of a glycoprotein enzyme based on the interaction of the 1, 2- or 1, 3-diols in the glycoprotein with a boronic acid functionalized monomer. Briefly, casting a mixture of glucose oxidase (GOx) and anilineboronic acid (ABA) followed by a NaAuCl(4) solution to an Au-plated Au electrode surface yielded a GOx-poly(ABA) (PABA)-gold nanoparticle (Au(nano)) bionanocomposite, and chitosan (CS) was then cast and air-dried. In the present protocol, the small-sized Au(nano) or Au subnanostructures can form near/on the enzyme molecule, which greatly promotes the electron transfer of enzymatic reaction and enhances the amperometric responses. The thus-prepared CS/GOx-PABA-Au(nano)/Au-plated Au electrode worked well in the first-/second generation biosensing modes and as a bioanode in a monopolar biofuel cell, with analytical or cell-power performance superior to those of most analogues hitherto reported. PMID:22099959

  13. Mammalian sensitivity to elemental gold (Au?)

    USGS Publications Warehouse

    Eisler, R.

    2004-01-01

    There is increasing documentation of allergic contact dermatitis and other effects from gold jewelry, gold dental restorations, and gold implants. These effects were especially pronounced among females wearing body-piercing gold objects. One estimate of the prevalence of gold allergy worldwide is 13%, as judged by patch tests with monovalent organogold salts. Eczema of the head and neck was the most common response of individuals hypersensitive to gold, and sensitivity can last for at least several years. Ingestion of beverages containing flake gold can result in allergic-type reactions similar to those seen in gold-allergic individuals exposed to gold through dermal contact and other routes. Studies with small laboratory mammals and injected doses of colloidal gold showed increased body temperatures, accumulations in reticular cells, and dose enhancement in tumor therapy; gold implants were associated with tissue injuries. It is proposed that Au? toxicity to mammals is associated, in part, with formation of the more reactive Au+ and Au3+ species.

  14. Photocatalysis enhancement of Au/BFO nanoparticles using plasmon resonance of Au NPs

    NASA Astrophysics Data System (ADS)

    Zhang, Yan; Cai, Zhongyang; Ma, Xueming

    2015-12-01

    BiFeO3 (BFO) nanoparticles was synthesized via sol-gel technique, and successfully loaded with small sizes of gold nanoparticles (Au NPs) by impregnation-reduction method to extremely enhance the BFO photocatalytic activity. The obviously stronger optical absorption of Au/BFO observed from the UV-vis diffuse reflectance spectrum confirmed that the surface plasmon resonance (SPR) effect occured on the surface of Au NPs. And the surface plasmon-induced localized electric field could allow the formation of electron/hole pairs in the near surface region of BFO which can migrate to the surface without undergoing electron/hole (e-/h+) pair recombination. The more electrons and holes formed, the more ·OH will be generated to decompose the CR solution. When the gold loading in Au/BFO nanoparticles is 3.36 wt%, the obtained Au/BFO catalyst exhibits best photocatalytic activity evaluated by photocatalysis degradation of Congo red (CR) solution under the visible light irradiation.

  15. Suppression of high transverse momentum π0 spectra in Au + Au collisions at RHIC

    NASA Astrophysics Data System (ADS)

    Kahana, D. E.; Kahana, S. H.

    2008-02-01

    Au + Au, s1/2 = 200 GeV measurements at RHIC, obtained with the PHENIX, STAR, PHOBOS and BRAHMS detectors, have all indicated a suppression of high p⊥ particle production, relative to an appropriately normalized NN level. For central collisions and vanishing pseudo-rapidity these experiments exhibit suppression in charged meson production, especially at medium-to-large transverse momenta. In the PHENIX experiment similar behaviour has been reported for π0 spectra. In a recent work [1] on the simpler D + Au interaction, to be considered perhaps as a tune-up for Au + Au, we reported on a pre-hadronic cascade mechanism which can explain the mixed observation of moderately reduced p⊥ suppression at higher pseudo-rapidity as well as the Cronin enhancement at mid-rapidity. Here, we present the extension of this work to the more massive ion-ion collisions. Our major thesis is that much of the suppression is generated in a late stage cascade of colourless pre-hadrons produced after an initial short-lived coloured phase. We present a pQCD argument to justify this approach and to estimate the time duration τp of this initial phase. Of essential importance is the brevity in time of the coloured phase existence relative to that of the strongly interacting pre-hadron phase, the latter essentially an interactive cascade. These distinctions in phase are of course not strict, but adequate for treating the suppression of moderate and high p⊥ mesons.

  16. Virus-templated Au and Au/Pt Core/shell Nanowires and Their Electrocatalytic Activitives for Fuel Cell Applications

    PubMed Central

    LEE, YOUJIN; KIM, JUNHYUNG; YUN, DONG SOO; NAM, YOON SUNG; SHAO-HORN, YANG; BELCHER, ANGELA M.

    2014-01-01

    A facile synthetic route was developed to make Au nanowires (NWs) from surfactant-mediated bio-mineralization of a genetically engineered M13 phage with specific Au binding peptides. From the selective interaction between Au binding M13 phage and Au ions in aqueous solution, Au NWs with uniform diameter were synthesized at room temperature with yields greater than 98 % without the need for size selection. The diameters of Au NWs were controlled from 10 nm to 50 nm. The Au NWs were found to be active for electrocatalytic oxidation of CO molecules for all sizes, where the activity was highly dependent on the surface facets of Au NWs. This low-temperature high yield method of preparing Au NWs was further extended to the synthesis of Au/Pt core/shell NWs with controlled coverage of Pt shell layers. Electro-catalytic studies of ethanol oxidation with different Pt loading showed enhanced activity relative to a commercial supported Pt catalyst, indicative of the dual functionality of Pt for the ethanol oxidation and Au for the anti-poisoning component of Pt. These new one-dimensional noble metal NWs with controlled compositions could facilitate the design of new alloy materials with tunable properties. PMID:24910712

  17. Reactivity of Two-Dimensional Au9, Pt9, and Au18Pt18 against Common Molecules.

    PubMed

    Takahashi, Lauren; Takahashi, Keisuke

    2016-09-19

    Adsorption of common molecules over two-dimensional Au9, Pt9, and Au18Pt18 is investigated with implementation of first-principles calculations. In general, it is found that Pt9 and Au18Pt18 exhibit low adsorption energies where Au18Pt18 preserves the structural integrity of the molecule and surface. In particular, adsorption of molecules onto Au18Pt18 frequently results in low adsorption energies and high reactivity with minor surface reconstruction of Au18Pt18 and average bond lengths of molecules. The decrease in adsorption energy can be attributed to the presence of platinum, while gold can be considered responsible for structural stability. In addition, molecule dissociation is observed in the cases of H2, HCl, CH4, SO, and SO2 when Pt atoms are involved. Thus, two-dimensional Au9, Pt9, and Au18Pt18 show low adsorption energies against common molecules, reflecting adsorption energies observed in small Au and Pt clusters. These results demonstrate that Au18Pt18 can successfully utilize the low adsorption energies associated with platinum while preserving the integrity of the surface structure using gold atoms, making it possible to adsorb desired molecules using select areas of the Au18Pt18 surface. PMID:27608367

  18. The Magic Au60 Nanocluster: A New Cluster-Assembled Material with Five Au13 Building Blocks.

    PubMed

    Song, Yongbo; Fu, Fangyu; Zhang, Jun; Chai, Jinsong; Kang, Xi; Li, Peng; Li, Shengli; Zhou, Hongping; Zhu, Manzhou

    2015-07-13

    Herein, we report the synthesis and atomic structure of the cluster-assembled [Au60Se2(Ph3P)10(SeR)15](+) material. Five icosahedral Au13 building blocks from a closed gold ring with Au-Se-Au linkages. Interestingly, two Se atoms (without the phenyl tail) locate in the center of the cluster, stabilized by the Se-(Au)5 interactions. The ring-like nanocluster is unprecedented in previous experimental and theoretical studies of gold nanocluster structures. In addition, our optical and electrochemical studies show that the electronic properties of the icosahedral Au13 units still remain unchanged in the penta-twinned Au60 nanocluster, and this new material might be a promising in optical limiting material. This work offers a basis for deep understanding on controlling the cluster-assembled materials for tailoring their functionalities.

  19. Ligand effects on the stability of thiol-stabilized gold nanoclusters: Au25(SR)18-, Au38(SR)24, and Au102(SR)44

    NASA Astrophysics Data System (ADS)

    Jung, Jaehoon; Kang, Sunwoo; Han, Young-Kyu

    2012-06-01

    We have studied the electrochemical and thermodynamic stability of Au25(SR)18-, Au38(SR)24, and Au102(SR)44, R = CH3, C6H13, CH2CH2Ph, Ph, PhF, and PhCOOH, in order to examine ligand effects on the stability of thiol-stabilized gold nanoclusters, Aum(SR)n. Aliphatic thiols, in general, have higher electrochemical and thermodynamic stability than aromatic thiols, and the -SCH2CH2Ph thiol is particularly appealing because of its high electrochemical and thermodynamic stability. The stabilization of Aum by nSR for Aum(SR)n can be rationalized by the stabilization of an Au atom by an SR for the simple molecule AuSR, regardless of interligand interaction and system size and shape. Thiol moieties play a strong role in the electron oxidation and reduction of Aum(SR)n. Accounting for the characteristics of thiol ligands is essential for understanding the electronic and thermodynamic stability of thiol-stabilized gold nanoclusters.We have studied the electrochemical and thermodynamic stability of Au25(SR)18-, Au38(SR)24, and Au102(SR)44, R = CH3, C6H13, CH2CH2Ph, Ph, PhF, and PhCOOH, in order to examine ligand effects on the stability of thiol-stabilized gold nanoclusters, Aum(SR)n. Aliphatic thiols, in general, have higher electrochemical and thermodynamic stability than aromatic thiols, and the -SCH2CH2Ph thiol is particularly appealing because of its high electrochemical and thermodynamic stability. The stabilization of Aum by nSR for Aum(SR)n can be rationalized by the stabilization of an Au atom by an SR for the simple molecule AuSR, regardless of interligand interaction and system size and shape. Thiol moieties play a strong role in the electron oxidation and reduction of Aum(SR)n. Accounting for the characteristics of thiol ligands is essential for understanding the electronic and thermodynamic stability of thiol-stabilized gold nanoclusters. Electronic supplementary information (ESI) available: HOMO, LUMO, and HOMO-LUMO gaps; optimized geometries and radial

  20. Au99(SPh)42 nanomolecules: aromatic thiolate ligand induced conversion of Au144(SCH2CH2Ph)60.

    PubMed

    Nimmala, Praneeth Reddy; Dass, Amala

    2014-12-10

    A new aromatic thiolate protected gold nanomolecule Au99(SPh)42 has been synthesized by reacting the highly stable Au144(SCH2CH2Ph)60 with thiophenol, HSPh. The ubiquitous Au144(SR)60 is known for its high stability even at elevated temperature and in the presence of excess thiol. This report demonstrates for the first time the reactivity of the Au144(SCH2CH2Ph)60 with thiophenol to form a different 99-Au atom species. The resulting Au99(SPh)42 compound, however, is unreactive and highly stable in the presence of excess aromatic thiol. The molecular formula of the title compound is determined by high resolution electrospray mass spectrometry (ESI-MS) and confirmed by the preparation of the 99-atom nanomolecule using two ligands, namely, Au99(SPh)42 and Au99(SPh-OMe)42. This mass spectrometry study is an unprecedented advance in nanoparticle reaction monitoring, in studying the 144-atom to 99-atom size evolution at such high m/z (∼12k) and resolution. The optical and electrochemical properties of Au99(SPh)42 are reported. Other substituents on the phenyl group, HS-Ph-X, where X = -F, -CH3, -OCH3, also show the Au144 to Au99 core size conversion, suggesting minimal electronic effects for these substituents. Control experiments were conducted by reacting Au144(SCH2CH2Ph)60 with HS-(CH2)n-Ph (where n = 1 and 2), bulky ligands like adamantanethiol and cyclohexanethiol. It was observed that conversion of Au144 to Au99 occurs only when the phenyl group is directly attached to the thiol, suggesting that the formation of a 99-atom species is largely influenced by aromaticity of the ligand and less so on the bulkiness of the ligand.

  1. Simulation of Electric Field in Semi Insulating Au/CdTe/Au Detector under Flux

    SciTech Connect

    Franc, J.; James, R.; Grill, R.; Kubat, J.; Belas, E.; Hoschl, P.; Moravec, P.; Praus, P.

    2009-08-02

    We report our simulations on the profile of the electric field in semi insulating CdTe and CdZnTe with Au contacts under radiation flux. The type of the space charge and electric field distribution in the Au/CdTe/Au structure is at high fluxes result of a combined influence of charge formed due to band bending at the electrodes and from photo generated carriers, which are trapped at deep levels. Simultaneous solution of drift-diffusion and Poisson equations is used for the calculation. We show, that the space charge originating from trapped photo-carriers starts to dominate at fluxes 10{sup 15}-10{sup 16}cm{sup -2}s{sup -1}, when the influence of contacts starts to be negligible.

  2. Electrochemical responses and electrocatalysis at single au nanoparticles.

    PubMed

    Li, Yongxin; Cox, Jonathan T; Zhang, Bo

    2010-03-10

    Steady-state electrochemical responses have been obtained at single Au nanoparticles using Pt nanoelectrodes. A Au single-nanoparticle electrode (SNPE) is constructed by chemically immobilizing a single Au nanoparticle at a SiO(2)-encapsulated Pt disk nanoelectrode, which was previously modified by an amine-terminated silane. The Au SNPE has been characterized by transmission electron microscopy, underpotential deposition of Cu, and steady-state cyclic voltammetry. It has been found that the presence of a single Au nanoparticle enhances the electron transfer from the Pt nanoelectrode to the redox molecules, and the voltammetric response at the Au SNPE depends on the size of the Au nanoparticle. The Au SNPE has been utilized to examine the oxygen-reduction reaction in a KOH solution to explore the feasibility of measuring the electrocatalytic activity at a single-nanoparticle level. It has been shown that the electrocatalytic activity of single Au nanoparticles can be directly measured using SNPEs, and the electrocatalytic activity is dependent on the size of the Au nanoparticles. This study can help to understand the structure-function relationship in nanoparticle-based electrocatalysis.

  3. Manipulation of superparamagnetic beads on patterned Au/Co/Au multilayers with perpendicular magnetic anisotropy

    NASA Astrophysics Data System (ADS)

    Jarosz, A.; Holzinger, D.; Urbaniak, M.; Ehresmann, A.; Stobiecki, F.

    2016-08-01

    The magnetophoresis of water-suspended 4 μm-diameter superparamagnetic beads above topographically patterned, sputter deposited Ti(4 nm)/Au(60 nm)/[Co(0.7 nm)/Au(1 nm)] × 3 multilayers with perpendicular magnetic anisotropy was investigated. The results impressively demonstrate that the magnetic stray field landscape above the stripe structure when superimposed with an external, slowly rotating, field enables the directed transport of magnetic beads across the stripe panel with velocities up to 12 μm s-1.

  4. Steering epitaxial alignment of Au, Pd, and AuPd nanowire arrays by atom flux change.

    PubMed

    Yoo, Youngdong; Seo, Kwanyong; Han, Sol; Varadwaj, Kumar S K; Kim, Hyun You; Ryu, Ji Hoon; Lee, Hyuck Mo; Ahn, Jae Pyoung; Ihee, Hyotcherl; Kim, Bongsoo

    2010-02-10

    We have synthesized epitaxial Au, Pd, and AuPd nanowire arrays in vertical or horizontal alignment on a c-cut sapphire substrate. We show that the vertical and horizontal nanowire arrays grow from half-octahedral seeds by the correlations of the geometry and orientation of seed crystals with those of as-grown nanowires. The alignment of nanowires can be steered by changing the atom flux. At low atom deposition flux vertical nanowires grow, while at high atom flux horizontal nanowires grow. Similar vertical/horizontal epitaxial growth is also demonstrated on SrTiO(3) substrates. This orientation-steering mechanism is visualized by molecular dynamics simulations.

  5. Admittance of Au/1,4-benzenedithiol/Au single-molecule junctions

    NASA Astrophysics Data System (ADS)

    Yamauchi, Kazumasa; Kurokawa, Shu; Sakai, Akira

    2012-12-01

    Employing the admittance formula for double-barrier junctions [Fu and Dudley, Phys. Rev. Lett. 70, 65 (1993)], we have estimated an ac susceptance (imaginary part of admittance) of Au/1,4-benzenedithiol/Au single-molecule junctions from their current-voltage characteristics. In the MHz regime, we find that the junction susceptance shows a very small (˜0.1 aF) capacitive component that can be entirely masked by a larger electrode capacitance. Direct ac signal transmission measurements up to 1 GHz reveal no molecular signals and confirm the smallness of the molecular capacitance in the MHz regime.

  6. Two-Particle Interferometry of 200 GeV Au+Au Collisions at PHENIX

    SciTech Connect

    Heffner, M

    2004-04-19

    The PHENIX experiment has measured pion-pion, kaon-kaon, and proton-proton correlations in Au+Au collisions at {radical}S{sub NN} = 200GeV. The correlations are fit to extract radii using both the Bowler Coulomb correction and full calculation of the two-particle wave function. The resulting radii are similar for all three species and decrease with increasing k{sub t} as expected for collective flow. The R{sub out} and R{sub side} radii are approximately equal indicating a short emission duration.

  7. Beam Energy Scan a Case for the Chiral Magnetic Effect in Au-Au Collisions

    SciTech Connect

    Longacre, R.

    2014-01-05

    The Chiral Magnetic Effect (CME) is predicted for Au-Au collisions at RHIC. However, many backgrounds can give signals that make the measurement hard to interpret. The STAR experiment has made measurements at different collisions energy ranging from √(sNN)=7.7 GeV to 62.4 GeV. In the analysis that is presented we show that the CME turns on with energy and is not present in central collisions where the induced magnetic is small.

  8. Relativistic multireference many-body perturbation theory calculations on Au64+ - Au69+ ions

    SciTech Connect

    Vilkas, M J; Ishikawa, Y; Trabert, E

    2006-03-31

    Many-body perturbation theory (MBPT) calculations are an adequate tool for the description of the structure of highly charged multi-electron ions and for the analysis of their spectra. They demonstrate this by way of a re-investigation of n=3, {Delta}n=0 transitions in the EUV spectra of Na-, Mg-, Al-like, and Si-like ions of Au that have been obtained previously by heavy-ion accelerator based beam-foil spectroscopy. They discuss the evidence and propose several revisions on the basis of the multi-reference many-body perturbation theory calculations of Ne- through P-like ions of Au.

  9. Gold nanoparticle (AuNPs) and gold nanopore (AuNPore) catalysts in organic synthesis.

    PubMed

    Takale, Balaram S; Bao, Ming; Yamamoto, Yoshinori

    2014-04-01

    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.

  10. Charged particle multiplicities in ultra-relativistic Au+Au and Cu+Cu collisions.

    SciTech Connect

    Alver, B.; Back, B. B.; Baker, M. D.; Ballintijn, M.; Barton, D. S.; PHOBOS Collaboration; Physics; Massachusetts Inst. of Tech.; BNL

    2006-01-01

    The PHOBOS collaboration has carried out a systematic study of charged particle multiplicities in Cu+Cu and Au+Au collisions at the Relativistic Heavy-Ion Collider (RHIC) at Brookhaven National Laboratory. A unique feature of the PHOBOS detector is its ability to measure charged particles over a very wide angular range from 0.5 to 179.5 deg. corresponding to |eta|<5.4. The general features of the charged particle multiplicity distributions as a function of pseudo-rapidity, collision energy and centrality, as well as system size, are discussed.

  11. Au/Pd core-shell nanoparticles with varied hollow Au cores for enhanced formic acid oxidation

    NASA Astrophysics Data System (ADS)

    Hsu, Chiajen; Huang, Chienwen; Hao, Yaowu; Liu, Fuqiang

    2013-03-01

    A facile method has been developed to synthesize Au/Pd core-shell nanoparticles via galvanic replacement of Cu by Pd on hollow Au nanospheres. The unique nanoparticles were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, transmission electron microscopy, ultraviolet-visible spectroscopy, and electrochemical measurements. When the concentration of the Au solution was decreased, grain size of the polycrystalline hollow Au nanospheres was reduced, and the structures became highly porous. After the Pd shell formed on these Au nanospheres, the morphology and structure of the Au/Pd nanoparticles varied and hence significantly affected the catalytic properties. The Au/Pd nanoparticles synthesized with reduced Au concentrations showed higher formic acid oxidation activity (0.93 mA cm-2 at 0.3 V) than the commercial Pd black (0.85 mA cm-2 at 0.3 V), suggesting a promising candidate as fuel cell catalysts. In addition, the Au/Pd nanoparticles displayed lower CO-stripping potential, improved stability, and higher durability compared to the Pd black due to their unique core-shell structures tuned by Au core morphologies.

  12. Electrostatic assembles and optical properties of Au CdTe QDs and Ag/Au CdTe QDs

    NASA Astrophysics Data System (ADS)

    Yang, Dongzhi; Wang, Wenxing; Chen, Qifan; Huang, Yuping; Xu, Shukun

    2008-09-01

    Au-CdTe and Ag/Au-CdTe assembles were firstly investigated through the static interaction between positively charged cysteamine-stabilized CdTe quantum dots (QDs) and negatively charged Au or core/shell Ag/Au nano-particles (NCs). The CdTe QDs synthesized in aqueous solution were capped with cysteamine which endowed them positive charges on the surface. Both Au and Ag/Au NCs were prepared through reducing precursors with gallic acid obtained from the hydrolysis of natural plant poly-phenols and favored negative charges on the surface of NCs. The fluorescence spectra of CdTe QDs exhibited strong quenching with the increase of added Au or Ag/Au NCs. Railey resonance scattering spectra of Au or Ag/Au NCs increased firstly and decreased latter with the concentration of CdTe QDs, accompanied with the solution color changing from red to purple and colorless at last. Experimental results on the effects of gallic acid, chloroauric acid tetrahydrate and other reagents demonstrated the static interaction occurred between QDs and NCs. This finding reveals the possibilities to design and control optical process and electromagnetic coupling in hybrid structures.

  13. Au/Pd core-shell nanoparticles with varied hollow Au cores for enhanced formic acid oxidation.

    PubMed

    Hsu, Chiajen; Huang, Chienwen; Hao, Yaowu; Liu, Fuqiang

    2013-03-01

    A facile method has been developed to synthesize Au/Pd core-shell nanoparticles via galvanic replacement of Cu by Pd on hollow Au nanospheres. The unique nanoparticles were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, transmission electron microscopy, ultraviolet-visible spectroscopy, and electrochemical measurements. When the concentration of the Au solution was decreased, grain size of the polycrystalline hollow Au nanospheres was reduced, and the structures became highly porous. After the Pd shell formed on these Au nanospheres, the morphology and structure of the Au/Pd nanoparticles varied and hence significantly affected the catalytic properties. The Au/Pd nanoparticles synthesized with reduced Au concentrations showed higher formic acid oxidation activity (0.93 mA cm-2 at 0.3 V) than the commercial Pd black (0.85 mA cm-2 at 0.3 V), suggesting a promising candidate as fuel cell catalysts. In addition, the Au/Pd nanoparticles displayed lower CO-stripping potential, improved stability, and higher durability compared to the Pd black due to their unique core-shell structures tuned by Au core morphologies.

  14. Au/Pd core-shell nanoparticles with varied hollow Au cores for enhanced formic acid oxidation

    PubMed Central

    2013-01-01

    A facile method has been developed to synthesize Au/Pd core-shell nanoparticles via galvanic replacement of Cu by Pd on hollow Au nanospheres. The unique nanoparticles were characterized by X-ray diffraction, X-ray photoelectron spectroscopy, transmission electron microscopy, ultraviolet–visible spectroscopy, and electrochemical measurements. When the concentration of the Au solution was decreased, grain size of the polycrystalline hollow Au nanospheres was reduced, and the structures became highly porous. After the Pd shell formed on these Au nanospheres, the morphology and structure of the Au/Pd nanoparticles varied and hence significantly affected the catalytic properties. The Au/Pd nanoparticles synthesized with reduced Au concentrations showed higher formic acid oxidation activity (0.93 mA cm-2 at 0.3 V) than the commercial Pd black (0.85 mA cm-2 at 0.3 V), suggesting a promising candidate as fuel cell catalysts. In addition, the Au/Pd nanoparticles displayed lower CO-stripping potential, improved stability, and higher durability compared to the Pd black due to their unique core-shell structures tuned by Au core morphologies. PMID:23452438

  15. Application de l'A.D.L, pour la mesure du champ de vitesses instationnaires de llecoulement a Ilechappement d'un moteur a combustion interne

    NASA Astrophysics Data System (ADS)

    Boutrif, M. S.; Thelliez, M.

    1993-01-01

    We present experimental results of instantaneous velocity measurement, which were obtained by application of the laser Doppler anemometry (L.D.A.) at the exhaust pipe of a reciprocating engine under real working conditions. First of all, we show that the instantaneous velocity is monodimensional along a straight exhaust pipe, and that the boundary layer develops within a 2mm thickness. We also show that the cylinder discharges in two phases : the blow down period and the final part of exhaust stroke. We also make obvious, that the flow escapes very quickly : its velocity varies between - 100m/s and 200m/s within a period shorter than 1ms ; thereby, we do record the acoustic resonance phenomenon, when the engine speed is greater than 3 000rpm. Finally, we show that in the exhaust pipe the apparent fluctuation - i.e. the cyclic dispersion and the actual turbulence - may reach 15%. Nous présentons des résultats expérimentaux du champ de vitesses instationnaires, obtenus par adaptation et application de la vélocimétrie laser interférentielle communément appelée à effet Doppler (L.D.A.), à l'échappement d'un moteur altematif à combustion inteme en fonctionnement nominal. Tout d'abord, nous montrons que dans un tube d'échappement long et droit, la vitesse instantanée est bien monodimensionnelle et que l'écoulement occupe la quasitotalité de la section droite géométrique du tube (une couche limite d'épaisseur inférieure à 2mm se développe très près de la paroi du tube). Nous pouvons également décrire la vidange du cylindre du moteur étudié en deux phases principales : bouffée d'échappement et refoulement des gaz brûlés par le piston. Nous mettons de même en évidence l'état très pulsé de l'écoulement, puisqu'en un intervalle de temps inférieur à 1ms, la vitesse de l'écoulement varie de - 100m/s à 200m/s ; nous enregistrons ainsi l'apparition du phénomène de résonance acoustique à des vitesses de rotation supérieures à 3 500

  16. APEX-CHAMP+ high-J CO observations of low-mass young stellar objects. III. NGC 1333 IRAS 4A/4B envelope, outflow, and ultraviolet heating

    NASA Astrophysics Data System (ADS)

    Yıldız, Umut A.; Kristensen, Lars E.; van Dishoeck, Ewine F.; Belloche, Arnaud; van Kempen, Tim A.; Hogerheijde, Michiel R.; Güsten, Rolf; van der Marel, Nienke

    2012-06-01

    Context. The NGC 1333 IRAS 4A and IRAS 4B sources are among the most well-studied Stage 0 low-mass protostars, which drive prominent bipolar outflows. Spectrally resolved molecular emission lines provide crucial information about the physical and chemical structure of the circumstellar material as well as the dynamics of the different components. Most studies have so far concentrated on the colder parts (T ≤ 30 K) of these regions. Aims: The aim is to characterize the warmer parts of the protostellar envelope using the new generation of submillimeter instruments. This will allow us to quantify the feedback of the protostars on their surroundings in terms of shocks, ultraviolet (UV) heating, photodissociation, and outflow dispersal. Methods: The dual frequency 2 × 7 pixel 650/850 GHz array receiver CHAMP+ mounted on APEX was used to obtain a fully sampled, large-scale ~4' × 4' map at 9″ resolution of the IRAS 4A/4B region in the 12CO J = 6-5 line. Smaller maps were observed in the 13CO 6-5 and [C i] J = 2-1 lines. In addition, a fully sampled 12CO J = 3-2 map made with HARP-B on the JCMT is presented and deep isotopolog observations are obtained at selected outflow positions to constrain the optical depth. Complementary Herschel-HIFI and ground-based lines of CO and its isotopologs, from J = 1-0 up to 10-9 (Eu/k ≈ 300 K), are collected at the source positions and used to construct velocity-resolved CO ladders and rotational diagrams. Radiative-transfer models of the dust and lines are used to determine the temperatures and masses of the outflowing and photon-heated gas and infer the CO abundance structure. Results: Broad CO emission-line profiles trace entrained shocked gas along the outflow walls, which have an average temperature of ~100 K. At other positions surrounding the outflow and the protostar, the 6-5 line profiles are narrow indicating UV excitation. The narrow 13CO 6-5 data directly reveal the UV heated gas distribution for the first time. The

  17. Atomic and molecular adsorption on Au(111)

    SciTech Connect

    Santiago-Rodríguez, Yohaselly; Herron, Jeffrey A.; Curet-Arana, María C.; Mavrikakis, Manos

    2014-09-01

    Periodic self-consistent density functional theory (DFT-GGA) calculations were used to study the adsorption of several atomic species, molecular species and molecular fragments on the Au(111) surface with a coverage of 1/4 monolayer (ML). Binding geometries, binding energies, and diffusion barriers were calculated for 27 species. Furthermore, we calculated the surface deformation energy associated with the binding events. The binding strength for all the analyzed species can be ordered as follows: NH3 < NO < CO < CH3 < HCO < NH2 < COOH < OH < HCOO < CNH2 < H < N < NH < NOH < COH < Cl,< HCO3 < CH2 < CN b HNO < O < F < S < C < CH. Although the atomic species preferred to bind at the three-fold fcc site, no tendency was observed in site preference for the molecular species and fragments. The intramolecular and adsorbate-surface vibrational frequencies were calculated for all the adsorbates on their most energetically stable adsorption site. Most of the theoretical binding energies and frequencies agreed with experimental values reported in the literature. In general, the values obtained with the PW91 functional are more accurate than RPBE in reproducing these experimental binding energies. The energies of the adsorbed species were used to calculate the thermochemical potential energy surfaces for decomposition of CO, NO, N2, NH3 and CH4, oxidation of CO, and hydrogenation of CO, CO2 and NO, giving insight into the thermochemistry of these reactions on gold nanoparticles. These potential energy surfaces demonstrated that: the decomposition of species is not energetically favorable on Au(111); the desorption of NH3, NO and CO are more favorable than their decomposition; the oxidation of CO and hydrogenation of CO and NO on Au(111) to form HCO and HNO, respectively, are also thermodynamically favorable.

  18. Anomalous magnetic moment at Ba in Au

    NASA Astrophysics Data System (ADS)

    Bhati, A. K.; Kaur, J.; Bansal, N.; Negi, D.; Kumar, R.; Bhowmik, R. K.; Kumar, V.; Dey, C. C.

    2015-04-01

    The Time differential perturbed angular distribution (TDPAD) technique is employed to measure the local susceptibility at the recoil implanted Ba ions in Au following the nuclear reaction 120Sn(12C, 3nγ)129Ba. We have observed first time the local paramagnetic susceptibility of 5.26(18) at Ba ions comparable to 4f-ions in any non-ferromagnetic metal at room temperature which seems to be related to the electronic s-d and s-f transfer at positive lattice pressure.

  19. Photosynthetic electron transport system promotes synthesis of Au-nanoparticles.

    PubMed

    Shabnam, Nisha; Pardha-Saradhi, P

    2013-01-01

    In this communication, a novel, green, efficient and economically viable light mediated protocol for generation of Au-nanoparticles using most vital organelle, chloroplasts, of the plant system is portrayed. Thylakoids/chloroplasts isolated from Potamogeton nodosus (an aquatic plant) and Spinacia oleracea (a terrestrial plant) turned Au³⁺ solutions purple in presence of light of 600 µmol m⁻² s⁻¹ photon flux density (PFD) and the purple coloration intensified with time. UV-Vis spectra of these purple colored solutions showed absorption peak at ∼545 nm which is known to arise due to surface plasmon oscillations specific to Au-nanoparticles. However, thylakoids/chloroplasts did not alter color of Au³⁺ solutions in dark. These results clearly demonstrated that photosynthetic electron transport can reduce Au³⁺ to Au⁰ which nucleate to form Au-nanoparticles in presence of light. Transmission electron microscopic studies revealed that Au-nanoparticles generated by light driven photosynthetic electron transport system of thylakoids/chloroplasts were in range of 5-20 nm. Selected area electron diffraction and powder X-ray diffraction indicated crystalline nature of these nanoparticles. Energy dispersive X-ray confirmed that these nanoparticles were composed of Au. To confirm the potential of light driven photosynthetic electron transport in generation of Au-nanoparticles, thylakoids/chloroplasts were tested for their efficacy to generate Au-nanoparticles in presence of light of PFD ranging from 60 to 600 µmol m⁻² s⁻¹. The capacity of thylakoids/chloroplasts to generate Au-nanoparticles increased remarkably with increase in PFD, which further clearly demonstrated potential of light driven photosynthetic electron transport in reduction of Au³⁺ to Au⁰ to form nanoparticles. The light driven donation of electrons to metal ions by thylakoids/chloroplasts can be exploited for large scale production of nanoparticles. PMID:23976990

  20. Photosynthetic electron transport system promotes synthesis of Au-nanoparticles.

    PubMed

    Shabnam, Nisha; Pardha-Saradhi, P

    2013-01-01

    In this communication, a novel, green, efficient and economically viable light mediated protocol for generation of Au-nanoparticles using most vital organelle, chloroplasts, of the plant system is portrayed. Thylakoids/chloroplasts isolated from Potamogeton nodosus (an aquatic plant) and Spinacia oleracea (a terrestrial plant) turned Au³⁺ solutions purple in presence of light of 600 µmol m⁻² s⁻¹ photon flux density (PFD) and the purple coloration intensified with time. UV-Vis spectra of these purple colored solutions showed absorption peak at ∼545 nm which is known to arise due to surface plasmon oscillations specific to Au-nanoparticles. However, thylakoids/chloroplasts did not alter color of Au³⁺ solutions in dark. These results clearly demonstrated that photosynthetic electron transport can reduce Au³⁺ to Au⁰ which nucleate to form Au-nanoparticles in presence of light. Transmission electron microscopic studies revealed that Au-nanoparticles generated by light driven photosynthetic electron transport system of thylakoids/chloroplasts were in range of 5-20 nm. Selected area electron diffraction and powder X-ray diffraction indicated crystalline nature of these nanoparticles. Energy dispersive X-ray confirmed that these nanoparticles were composed of Au. To confirm the potential of light driven photosynthetic electron transport in generation of Au-nanoparticles, thylakoids/chloroplasts were tested for their efficacy to generate Au-nanoparticles in presence of light of PFD ranging from 60 to 600 µmol m⁻² s⁻¹. The capacity of thylakoids/chloroplasts to generate Au-nanoparticles increased remarkably with increase in PFD, which further clearly demonstrated potential of light driven photosynthetic electron transport in reduction of Au³⁺ to Au⁰ to form nanoparticles. The light driven donation of electrons to metal ions by thylakoids/chloroplasts can be exploited for large scale production of nanoparticles.

  1. Evaluation of the Olympus AU 400 clinical chemistry analyzer.

    PubMed

    Bilić, A; Alpeza, I; Rukavina, A S

    2000-01-01

    The performance of the Olympus AU 400 clinical chemistry analyzer was evaluated according to the guidelines of the European Committee for Clinical Laboratory Standards. The following analytes were tested: glucose, urea, creatinine, calcium, AST, ALT, CK, LDH, ALP and amylase. The Olympus AU 400 was compared with the Olympus AU 800. Coefficients of correlation showed high correlation between the compared analyzers. Other performances (intra- and inter-assay variation, carry-over and interferences) of the analyzer were satisfactory.

  2. Systematic studies of the centrality dependence of soft photon production in Au + Au collision with PHENIX

    NASA Astrophysics Data System (ADS)

    Bannier, Benjamin

    2014-11-01

    Since the earliest days of Heavy Ion Physics thermal soft photon radiation emitted during the reaction had been theorized as a smoking gun signal for formation of a quark-gluon plasma and as a tool to characterize its properties. In recent years the existence of excess photon radiation in heavy ion collisions over the expectation from initial hard interactions has been confirmed at both RHIC and LHC energies by PHENIX and ALICE respectively. There the radiation has been found to exhibit elliptic flow v2 well above what can currently be reconciled with a picture of early emission from a plasma phase. During the 2007 and 2010 Au + Au runs PHENIX has measured a high purity sample of soft photons down to pT > 0.4 GeV / c using an external conversion method. We present recent systematic studies by PHENIX from that sample on the centrality dependence of the soft photon yield, and elliptic and triangular flow v2 and v3 in Au + Au collisions which fill in the experimental picture and enable discrimination of competing soft photon production scenarios.

  3. Degree of chemical nonequilibrium in central Au-Au collisions at RHIC energies

    NASA Astrophysics Data System (ADS)

    Tawfik, Abdel Nasser; El-Bakry, M. Y.; Habashy, D. M.; Mohamed, M. T.; Abbas, Ehab

    2015-08-01

    In this paper, we investigate the difference between hadron resonance gas (HRG) calculations for chemical freeze-out parameters at fully and partly chemical equilibria. To this end, the results are compared with the particle ratios measured in central Au-Au collisions at a wide range of nucleon-nucleon center-of-mass energies, √ {s{ NN}} = 7.7 - 200 GeV as offered by the STAR experiment. We restrict the discussion to STAR, because of large statistics and overall homogeneity of STAR measurements (one detector) against previous experiments. We find that the matter produced at these energies is likely in fully chemical equilibria, which is consistent with recent lattice quantum chromodynamics (QCD) results. The possible improvements by partial chemical equilibria (γS ≠ 1) are very limited. We also discuss these results with the ones deduced from ϕ/π- and Ω-/π- ratios. These hadron ratios are sensitive to the degree of chemical equilibrium. Accordingly, the conclusion that the matter produced reaches fully chemical equilibria in central Au-Au at relativistic heavy-ion collider (RHIC) energies is confirmed.

  4. "Au Revoir" to Film Illiteracy: An Interdisciplinary Exploration of "Au Revior Les Enfants."

    ERIC Educational Resources Information Center

    Corbitt, J. Catherine

    1998-01-01

    Discusses the power of film and films as teaching tools. Describes how the 1987 French film "Au Revior Les Enfants" can serve these purposes. Discusses its historical context, and ways to show the film in class. Lists numerous topics (on important film themes, and on technical aspects of film) for student projects. (SR)

  5. Charged-particle rapidity density in Au+Au collisions in a quark combination model

    NASA Astrophysics Data System (ADS)

    Shao, Feng-Lan; Yao, Tao; Xie, Qu-Bing

    2007-03-01

    Rapidity/pseudorapidity densities for charged particles and their centrality, rapidity, and energy dependence in Au+Au collisions at the Relativistic Heavy Ion Collider are studied in a quark combination model. Using a Gaussian-type rapidity distribution for constituent quarks as a result of Landau hydrodynamic evolution, the data at sNN=130,200 GeV at various centralities in full pseudorapidity range are well described, and the charged-particle multiplicities are reproduced as functions of the number of participants. The energy dependence of the shape of the dNch/dη distribution is also described at various collision energies sNN=200,130,62.4 GeV in central collisions with same value of parameters except 19.6 GeV. The calculated rapidity distributions and yields for the charged pions and kaons in central Au+Au collisions at sNN=200 GeV are compared with experimental data of the BRAHMS Collaboration.

  6. Divided café-au-lait macule of the mouth.

    PubMed

    Sergay, Amanda; Silverberg, Nanette B

    2007-05-01

    We describe a 4-year-old, otherwise healthy boy with a congenital history of a perioral and labial segmental café-au-lait macule, who was noted to have unilateral localized gingival hyperpigmentation that aligned with the café-au-lait macule. This case is highly illustrative of the embryologic timing of the genetic event locally, which leads to café-au-lait type hyperpigmentation. Because the facial features and the ectoderm overlying the facial muscles develop around the third to fourth week of gestation, the distribution of this café-au-lait macule suggests development at the same time.

  7. Enhanced photoluminescence in Au-embedded ITO nanowires.

    PubMed

    Kim, Hyunsu; Park, Sunghoon; Jin, Changhyun; Lee, Chongmu

    2011-12-01

    Gold (Au)-embedded indium tin oxide (ITO) nanowires were synthesized by thermal evaporation of a mixture of In(2)O(3,) SnO(2) and graphite powders on Si (100) substrates coated with Au thin films followed by annealing. At the initial stages of annealing, Au formed a continuous linear core located along the long axis of each ITO nanowire. The morphology of the Au core changed from a continuous line to a discrete line, and then to a droplet-like chain, finally evolving into a peapod in which crystalline Au nanoparticles were encapsulated in crystalline ITO with increasing annealing temperature. The ITO nanowires with the Au core showed an emission band at ~380 nm in the ultraviolet region. The ultraviolet emission intensity increased rapidly with increasing annealing temperature. The intensity of emission from the Au-peapod ITO nanowires (annealed at 750 °C) was approximately 20 times higher than that of the emission from the Au-core/ITO-shell ITO nanowires with a continuous linear shaped-Au core (annealed at 550 °C). This ultraintense ultraviolet emission might have originated mainly from the enhanced crystalline quality of the annealed ITO nanowires. PMID:22087582

  8. Heatless synthesis of well dispersible Au nanoparticles using pectin biopolymer.

    PubMed

    Ahmed, Hanan B; Zahran, M K; Emam, Hossam E

    2016-10-01

    Due to its potency to utilize in enormous applications, preparation of nanogold is of interest. Moreover, getting of highly dispersed nanogold with small size is extremely needful in specific fields. Herein, Au nanocolloid was prepared using alkali catalyzed pectin biopolymer. Pectin was concurrently used as reductant for Au ions and stabilizer for the produced Au nanoparticles (AuNPs). Reducing sugars were evaluated in the colloidal solution reflecting the role alkali in catalytic degradation of pectin to produce much powerful reducing moieties. The obtained Au nanocolloid was monitored via changing in color, UV-visible spectral and transmission electron microscopy. Using of NaOH as strong alkali achieving rapid rate of degradation reaction, resulted in 0.45g/L reducing sugars from 0.2g/L pectin which produced AuNPs with mean size of 6.5nm. In case of Na2CO3 which attained slow degradation rate led to, slightly low reducing sugar content (0.41g/L), fabricated comparatively size of AuNPs (7.5nm). In both cases, well distributed AuNPs was obtained with suitable stabilization up to 5 months and Na2CO3 exhibited higher stability. The current successful method used to produce small sized AuNPs with high dispersion is an innovative, one-step, easily, costless, energy saving and eco-friendly method.

  9. An Exploration of Catalytic Chemistry on Au/Ni(111)

    SciTech Connect

    Sylvia T. Ceyer

    2011-12-09

    This project explored the catalytic oxidation chemistry that can be effected on a Au/Ni(111) surface alloy. A Au/Ni(111) surface alloy is a Ni(111) surface on which less than 60% of the Ni atoms are replaced at random positions by Au atoms. The alloy is produced by vapor deposition of a small amount of Au onto Ni single crystals. The Au atoms do not result in an epitaxial Au overlayer or in the condensation of the Au into droplets. Instead, Au atoms displace and then replace Ni atoms on a Ni(111) surface, even though Au is immiscible in bulk Ni. The two dimensional structure of the clean Ni surface is preserved. This alloy is found to stabilize an adsorbed peroxo-like O2 species that is shown to be the critical reactant in the low temperature catalytic oxidation of CO and that is suspected to be the critical reactant in other oxidation reactions. This investigation revealed a new, practically important catalyst for CO oxidation that has since been patented.

  10. Preparations for p-Au run in 2015

    SciTech Connect

    Liu, C.

    2014-12-31

    The p-Au particle collision is a unique category of collision runs. This is resulted from the different charge mass ratio of the proton and fully stripped Au ion (1 vs.79/197). The p-Au run requires a special acceleration ramp, and movement of a number of beam components as required by the beam trajectories. The DX magnets will be moved for the first time in the history of RHIC. In this note, the planning and preparations for p-Au run will be presented.

  11. Heatless synthesis of well dispersible Au nanoparticles using pectin biopolymer.

    PubMed

    Ahmed, Hanan B; Zahran, M K; Emam, Hossam E

    2016-10-01

    Due to its potency to utilize in enormous applications, preparation of nanogold is of interest. Moreover, getting of highly dispersed nanogold with small size is extremely needful in specific fields. Herein, Au nanocolloid was prepared using alkali catalyzed pectin biopolymer. Pectin was concurrently used as reductant for Au ions and stabilizer for the produced Au nanoparticles (AuNPs). Reducing sugars were evaluated in the colloidal solution reflecting the role alkali in catalytic degradation of pectin to produce much powerful reducing moieties. The obtained Au nanocolloid was monitored via changing in color, UV-visible spectral and transmission electron microscopy. Using of NaOH as strong alkali achieving rapid rate of degradation reaction, resulted in 0.45g/L reducing sugars from 0.2g/L pectin which produced AuNPs with mean size of 6.5nm. In case of Na2CO3 which attained slow degradation rate led to, slightly low reducing sugar content (0.41g/L), fabricated comparatively size of AuNPs (7.5nm). In both cases, well distributed AuNPs was obtained with suitable stabilization up to 5 months and Na2CO3 exhibited higher stability. The current successful method used to produce small sized AuNPs with high dispersion is an innovative, one-step, easily, costless, energy saving and eco-friendly method. PMID:27212212

  12. Enhanced ultraviolet photoresponse in Au/ZnO nanorods

    NASA Astrophysics Data System (ADS)

    Mahanti, Moumita; Basak, Durga

    2014-09-01

    ZnO nanorods (NRs) have been decorated by Au nanoparticles (NPs) by a chemical method. The ultraviolet (UV) photoresponse of Au/ZnO NRs has been investigated. As the loading of Au NPs increases, the photocurrent as well as the photo-to-dark current ratio (gain) increases attaining a maximum gain value which is ∼15 times higher than that of the pristine ZnO NRs. Photoresponse enhancement is probably due to efficient separation of photo-generated electron-holes by an enhanced electric field and hot carrier injection over the Au localized Schottky junctions.

  13. Heterostructured Au/Pd-M (M = Au, Pd, Pt) nanoparticles with compartmentalized composition, morphology, and electrocatalytic activity.

    PubMed

    Lutz, Patrick S; Bae, In-Tae; Maye, Mathew M

    2015-10-14

    The synthesis, processing, and galvanic exchange of three heterostructured nanoparticle systems is described. The surface accessibility and redox potential of a Au/Pd-Ag dumbbell nanoparticle, where a Au/Pd core/shell region, and a silver region make up the domains, was used to prepare the new nanostructures with controlled composition, morphology, and microstructure. Results indicate that the silver domain was particularly susceptible to galvanic displacement, and was exchanged to Au/Pd-M (M = Au, Pd, Pt). Interestingly, the dumbbell morphology remained after exchange, and the silver region was transformed to hollow, parachute, or concentric domains respectively. The morphology and microstructure change was visualized via TEM and HRTEM, and the composition changes were probed via STEM-EDS imaging and XPS. The electrocatalytic activity of the Au/Pd-M towards methanol oxidation was studied, with results indicating that the Au/Pd-Pt nanoparticles had high activity attributed to the porous nature of the platinum domains. PMID:26351824

  14. Baryon Stopping in Au+Au and p+p collisions at 62 and 200 GeV

    NASA Astrophysics Data System (ADS)

    Brahms Collaboration; Dalsgaard, Hans Hjersing; BRAHMS Collaboration

    2009-11-01

    BRAHMS has measured rapidity density distributions of protons and antiprotons in both p+p and Au+Au collisions at 62 GeV and 200 GeV. From these distributions the yields of so-called ‘net-protons’, that is the difference between the proton and antiproton yields, can be determined. The rapidity dependence of the net-proton yields from peripheral Au+Au collisions is found to have a similar behaviour to that found for the p+p results, while a quite different rapidity dependence is found for central Au+Au collisions. The net-proton distributions can be used together with model calculations to find the net-baryon yields as a function of rapidity, thus yielding information on the average rapidity loss of beam particles, the baryon transport properties of the medium, and the amount of ‘stopping’ in these collisions.

  15. Component conversion from pure Au nanorods to multiblock Ag-Au-Ag nanorods assisted by Pt nanoframe templates

    NASA Astrophysics Data System (ADS)

    Lee, Sangji; Jang, Hee-Jeong; Jang, Ho Young; Kim, Seong Kyu; Park, Sungho

    2016-06-01

    We developed a new method for synthesizing multiblock Ag-Au-Ag nanorods using Pt nanoframes that had been deposited on the edges of Au nanorod seeds. As a function of Au etching time, the length of the Au nanorod decreased symmetrically starting from the two ends, leading to the formation of empty inner space at the ends. Subsequent reduction of Ag ions could be selectively performed in the inner space confined by Pt nanoframes and the resulting Ag-Au-Ag nanorods exhibited characteristic LSPR modes originating from each block component (in a transverse direction) and SPR coupling (in a longitudinal direction). The high quality of the resulting multiblock nanorods enabled observation of the longitudinal quadrupole mode that was induced by Ag-Au SPR coupling in a long axis. The mode exhibited high sensitivity in accordance with the change in the surrounding media, demonstrating great potential for sensor applications.We developed a new method for synthesizing multiblock Ag-Au-Ag nanorods using Pt nanoframes that had been deposited on the edges of Au nanorod seeds. As a function of Au etching time, the length of the Au nanorod decreased symmetrically starting from the two ends, leading to the formation of empty inner space at the ends. Subsequent reduction of Ag ions could be selectively performed in the inner space confined by Pt nanoframes and the resulting Ag-Au-Ag nanorods exhibited characteristic LSPR modes originating from each block component (in a transverse direction) and SPR coupling (in a longitudinal direction). The high quality of the resulting multiblock nanorods enabled observation of the longitudinal quadrupole mode that was induced by Ag-Au SPR coupling in a long axis. The mode exhibited high sensitivity in accordance with the change in the surrounding media, demonstrating great potential for sensor applications. Electronic supplementary information (ESI) available. See DOI: 10.1039/c6nr03484e

  16. Ordered arrays of Au catalysts by FIB assisted heterogeneous dewetting

    NASA Astrophysics Data System (ADS)

    Benkouider, A.; Ronda, A.; David, T.; Favre, L.; Abbarchi, M.; Naffouti, M.; Osmond, J.; Delobbe, A.; Sudraud, P.; Berbezier, I.

    2015-12-01

    Synthesizing Au0.8Si0.2 nanocatalysts that are homogeneous in size and have controlled position is becoming a challenging and crucial prequisite for the fabrication of ordered semiconductor nanowires. In this study, Au0.8Si0.2 nanocatalysts are synthesized via dewetting of Au layers on Si(111) during thermal annealing in an ultra-high vacuum. In the first part of the paper, the mechanism of homogeneous dewetting is analyzed as a function of the Au-deposited thickness (h Au). We distinguish three different dewetting regimes: (I) for a low thickness ({h}{{Au}}≤slant 0.4 {nm}), a submonolyer coverage of Au is stabilized and there is no dewetting. (II) For an intermediate thickness (0.4 {nm}\\lt {h}{Au}≤slant 5 {nm}), there is both dewetting and Au0.8Si0.2 phase formation. The size and density of the Au0.8Si0.2 clusters are directly related to h Au. When cooling down to room temperature, the clusters decompose and reject the Si at the Au/Si substrate interface. (III) For a large thickness ({h}{{Au}}\\gt 5 {nm}), only dewetting takes place, without forming AuSi clusters. In this regime, the dewetting is kinetically controlled by the self-diffusion of Au (activation energy ∼0.43 eV) without evidence of an Si-alloying effect. As a practical consequence, when relying solely on the homogeneous dewetting of Au/Si(111) to form the Au0.8Si0.2 catalysts (without a supply of Si atoms from vapor), regime II should be used to obtain good size and density control. In the second part of the paper, a process for ordering the catalysts using focused ion beam-(FIB) assisted dewetting (heterogeneous dewetting) is developed. We show that no matter what the FIB milling conditions and the Au nominal thickness are, dewetting is promoted by ion beam irradiation and is accompanied by the formation of Au0.8Si0.2 droplets. The droplets preferentially form on the patterned areas, while in similar annealing conditions, they do not form on the unpatterned areas. This behavior is attributed

  17. Gold Apes Hydrogen. The Structure and Bonding in the Planar B7Au2- and B7Au2 Clusters

    SciTech Connect

    Zhai, Hua JIN.; Wang, Lai S.; Zubarev, Dmitry Y.; Boldyrev, Alexander I.

    2006-02-09

    We produced the B7Au2- mixed cluster and studied its electronic structure and chemical bonding using photoelectron spectroscopy and ab initio calculations. The photoelectron spectra of B7Au2- were observed to be relatively simple with vibrational resolution, in contrast to the complicated spectra observed for pure B7-, which had contributions from three isomers (Alexandrova et al., J. Phys. Chem. A, 2004, 108, 3509). Theoretical calculations show that B7Au2- possesses an extremely stable planar structure, identical to that of B7H2-, demonstrating that Au mimics H in its bonding to boron, analogous to the Au-Si bonding. The ground state structure of B7Au2- (B7H2-) can be viewed as adding two Au (H) atoms to the terminal B atoms of a higher-lying planar isomer of B7-. The bonding and stability in the planar B7Au2- (B7H2-) clusters are elucidated on the basis of the strong covalent B-Au (H) bonding and the concepts of aromaticity/antiaromaticity in these systems.

  18. PHENIX Results for J/{psi} Transverse Momentum and Rapidity Dependence in Au+Au and Cu+Cu Collisions

    SciTech Connect

    Glenn, A. M.; Awes, Terry C; Batsouli, Sotiria; Cianciolo, Vince; Efremenko, Yuri; Read Jr, Kenneth F; Silvermyr, David O; Sorensen, Soren P; Stankus, Paul W; Young, Glenn R; Zhang, Chun; PHENIX, Collaboration

    2007-01-01

    The PHENIX experiment at RHIC has measured J/{psi} production in {radical}(s{sub NN})=200 GeV Au+Au and Cu+Cu collisions at forward (1.2 < |y| < 2.2) and mid (|y| < 0.35) rapidities. The most recent results for the rapidity and transverse momentum dependence of J/{psi} production are presented and compared with PHENIX baseline p + p measurements and selected theoretical calculations. We find that the J/{psi} production is significantly more suppressed, as compared to p + p, at forward rapidity than at mid rapidity in central Au+Au collisions.

  19. Strange baryon resonance production in sqrt s NN=200 GeV p+p and Au+Au collisions.

    PubMed

    Abelev, B I; Aggarwal, M M; Ahammed, Z; Amonett, J; Anderson, B D; Anderson, M; Arkhipkin, D; Averichev, G S; Bai, Y; Balewski, J; Barannikova, O; Barnby, L S; Baudot, J; Bekele, S; Belaga, V V; Bellingeri-Laurikainen, A; Bellwied, R; Benedosso, F; Bhardwaj, S; Bhasin, A; Bhati, A K; Bichsel, H; Bielcik, J; Bielcikova, J; Bland, L C; Blyth, S-L; Bonner, B E; Botje, M; Bouchet, J; Brandin, A V; Bravar, A; Burton, T P; Bystersky, M; Cadman, R V; Cai, X Z; Caines, H; Calderón de la Barca Sánchez, M; Castillo, J; Catu, O; Cebra, D; Chajecki, Z; Chaloupka, P; Chattopadhyay, S; Chen, H F; Chen, J H; Cheng, J; Cherney, M; Chikanian, A; Christie, W; Coffin, J P; Cormier, T M; Cosentino, M R; Cramer, J G; Crawford, H J; Das, D; Das, S; Dash, S; Daugherity, M; de Moura, M M; Dedovich, T G; DePhillips, M; Derevschikov, A A; Didenko, L; Dietel, T; Djawotho, P; Dogra, S M; Dong, W J; Dong, X; Draper, J E; Du, F; Dunin, V B; Dunlop, J C; Dutta Mazumdar, M R; Eckardt, V; Edwards, W R; Efimov, L G; Emelianov, V; Engelage, J; Eppley, G; Erazmus, B; Estienne, M; Fachini, P; Fatemi, R; Fedorisin, J; Filimonov, K; Filip, P; Finch, E; Fine, V; Fisyak, Y; Fu, J; Gagliardi, C A; Gaillard, L; Ganti, M S; Gaudichet, L; Ghazikhanian, V; Ghosh, P; Gonzalez, J E; Gorbunov, Y G; Gos, H; Grebenyuk, O; Grosnick, D; Guertin, S M; Guimaraes, K S F F; Gupta, N; Gutierrez, T D; Haag, B; Hallman, T J; Hamed, A; Harris, J W; He, W; Heinz, M; Henry, T W; Hepplemann, S; Hippolyte, B; Hirsch, A; Hjort, E; Hoffman, A M; Hoffmann, G W; Horner, M J; Huang, H Z; Huang, S L; Hughes, E W; Humanic, T J; Igo, G; Jacobs, P; Jacobs, W W; Jakl, P; Jia, F; Jiang, H; Jones, P G; Judd, E G; Kabana, S; Kang, K; Kapitan, J; Kaplan, M; Keane, D; Kechechyan, A; Khodyrev, V Yu; Kim, B C; Kiryluk, J; Kisiel, A; Kislov, E M; Klein, S R; Kocoloski, A; Koetke, D D; Kollegger, T; Kopytine, M; Kotchenda, L; Kouchpil, V; Kowalik, K L; Kramer, M; Kravtsov, P; Kravtsov, V I; Krueger, K; Kuhn, C; Kulikov, A I; Kumar, A; Kuznetsov, A A; Lamont, M A C; Landgraf, J M; Lange, S; LaPointe, S; Laue, F; Lauret, J; Lebedev, A; Lednicky, R; Lee, C-H; Lehocka, S; LeVine, M J; Li, C; Li, Q; Li, Y; Lin, G; Lin, X; Lindenbaum, S J; Lisa, M A; Liu, F; Liu, H; Liu, J; Liu, L; Liu, Z; Ljubicic, T; Llope, W J; Long, H; Longacre, R S; Love, W A; Lu, Y; Ludlam, T; Lynn, D; Ma, G L; Ma, J G; Ma, Y G; Magestro, D; Mahapatra, D P; Majka, R; Mangotra, L K; Manweiler, R; Margetis, S; Markert, C; Martin, L; Matis, H S; Matulenko, Yu A; McClain, C J; McShane, T S; Melnick, Yu; Meschanin, A; Millane, J; Miller, M L; Minaev, N G; Mioduszewski, S; Mironov, C; Mischke, A; Mishra, D K; Mitchell, J; Mohanty, B; Molnar, L; Moore, C F; Morozov, D A; Munhoz, M G; Nandi, B K; Nattrass, C; Nayak, T K; Nelson, J M; Netrakanti, P K; Nogach, L V; Nurushev, S B; Odyniec, G; Ogawa, A; Okorokov, V; Oldenburg, M; Olson, D; Pachr, M; Pal, S K; Panebratsev, Y; Panitkin, S Y; Pavlinov, A I; Pawlak, T; Peitzmann, T; Perevoztchikov, V; Perkins, C; Peryt, W; Phatak, S C; Picha, R; Planinic, M; Pluta, J; Poljak, N; Porile, N; Porter, J; Poskanzer, A M; Potekhin, M; Potrebenikova, E; Potukuchi, B V K S; Prindle, D; Pruneau, C; Putschke, J; Rakness, G; Raniwala, R; Raniwala, S; Ray, R L; Razin, S V; Reinnarth, J; Relyea, D; Retiere, F; Ridiger, A; Ritter, H G; Roberts, J B; Rogachevskiy, O V; Romero, J L; Rose, A; Roy, C; Ruan, L; Russcher, M J; Sahoo, R; Sakuma, T; Salur, S; Sandweiss, J; Sarsour, M; Sazhin, P S; Schambach, J; Scharenberg, R P; Schmitz, N; Schweda, K; Seger, J; Selyuzhenkov, I; Seyboth, P; Shabetai, A; Shahaliev, E; Shao, M; Sharma, M; Shen, W Q; Shimanskiy, S S; Sichtermann, E; Simon, F; Singaraju, R N; Smirnov, N; Snellings, R; Sood, G; Sorensen, P; Sowinski, J; Speltz, J; Spinka, H M; Srivastava, B; Stadnik, A; Stanislaus, T D S; Stock, R; Stolpovsky, A; Strikhanov, M; Stringfellow, B; Suaide, A A P; Sugarbaker, E; Sumbera, M; Sun, Z; Surrow, B; Swanger, M; Symons, T J M; Szanto de Toledo, A; Tai, A; Takahashi, J; Tang, A H; Tarnowsky, T; Thein, D; Thomas, J H; Timmins, A R; Timoshenko, S; Tokarev, M; Trainor, T A; Trentalange, S; Tribble, R E; Tsai, O D; Ulery, J; Ullrich, T; Underwood, D G; Buren, G Van; van der Kolk, N; van Leeuwen, M; Molen, A M Vander; Varma, R; Vasilevski, I M; Vasiliev, A N; Vernet, R; Vigdor, S E; Viyogi, Y P; Vokal, S; Voloshin, S A; Waggoner, W T; Wang, F; Wang, G; Wang, J S; Wang, X L; Wang, Y; Watson, J W; Webb, J C; Westfall, G D; Wetzler, A; Whitten, C; Wieman, H; Wissink, S W; Witt, R; Wood, J; Wu, J; Xu, N; Xu, Q H; Xu, Z; Yepes, P; Yoo, I-K; Yurevich, V I; Zhan, W; Zhang, H; Zhang, W M; Zhang, Y; Zhang, Z P; Zhao, Y; Zhong, C; Zoulkarneev, R; Zoulkarneeva, Y; Zubarev, A N; Zuo, J X

    2006-09-29

    We report the measurements of Sigma(1385) and Lambda(1520) production in p+p and Au+Au collisions at sqrt[s{NN}]=200 GeV from the STAR Collaboration. The yields and the p(T) spectra are presented and discussed in terms of chemical and thermal freeze-out conditions and compared to model predictions. Thermal and microscopic models do not adequately describe the yields of all the resonances produced in central Au+Au collisions. Our results indicate that there may be a time span between chemical and thermal freeze-out during which elastic hadronic interactions occur. PMID:17026027

  20. Ultrafast charge carrier dynamics in Au/semiconductor nanoheterostructures

    NASA Astrophysics Data System (ADS)

    Lambright, Scott

    The charge carrier dynamics in several Au/semiconductor core/shell heterostructures were examined. Firstly, Au/CdS core/shell nanocomposites were synthesized in a four step procedure culminating in a cation exchange performed on the shell. Previous studies of the ultrafast carrier dynamics in Au/CdS nanocomposites with epitaxial boundary regions reported the suppression of plasmon character in transient absorption spectra accompanied by broadband photoinduced absorption. The coupling of electron wavefunctions with lattice defects at the boundary of the two domains has been blamed for these phenomena. In the current study, transmission electron micrographs of Au/CdS synthesized using cation exchange showed no evidence of strain on the lattice of either component, while femtosecond transient absorption data show the retention of bleach regions attributed to CdS's 1S(e)-1S3/2(h) transition and Au's plasmon resonance. Accelerated rates of bleach recovery for both excitations ( tauexiton ≈ 300 ps, tauplasmon ≈ .7 ps) indicated that the interaction of Au and CdS domains leads to faster relaxation to their respective photoexcitations when compared to relaxation times in isolated Au and CdS nanoparticles. It was believed that the Au/CdS boundary was non-epitaxial in the presented core/shell nanocomposites. Secondly, these non-epitaxial Au/CdS core/shells were subsequently used to demonstrate near-field energy transfer from 5 nm diameter Au cores to CdS-encapsulated CdSe quantum dots. To this end, Au/CdS and CdSe/CdS nanocrystals were embedded in semiconductor-matrix-encapsulated-nanocrystal-arrays (SMENA) together. The encapsulation of both domains in the high band-gap semiconductor CdS was a means to suppress charge transfer between the two nanoparticles. The fluorescence intensity in these films was enhanced 6-fold in some cases as a result of the presence of Au domains. It was also demonstrated that the fluorescence enhancement was independent of the potential

  1. Microstructural evolution of eutectic Au-Sn solder joints

    SciTech Connect

    Song, Ho Geon

    2002-05-31

    Current trends toward miniaturization and the use of lead(Pb)-free solder in electronic packaging present new problems in the reliability of solder joints. This study was performed in order to understand the microstructure and microstructural evolution of small volumes of nominally eutectic Au-Sn solder joints (80Au-20Sn by weight), which gives insight into properties and reliability.

  2. Registration of ‘AU-1101’ peanut

    Technology Transfer Automated Retrieval System (TEKTRAN)

    AU-1101’ (Reg. No. CV-xxx, PI 661498) is a large-seeded virginia-type peanut (Arachis hypogaea L. subsp. hypogaea var. hypogaea) with high yield and medium maturity, uniform pod size and shape, high grade, superior shelling characters, low oil content, normal oleic acid content, and good flavor. AU-...

  3. Experimental Evidence for Electron Channeling in Fe/ Au (100) Superlattices

    SciTech Connect

    Dekadjevi, D. T.; Ryan, P. A.; Hickey, B. J.; Fulthorpe, B. D.; Tanner, B. K.

    2001-06-18

    We present transport and structural data from epitaxial (100) and (111) Au/Fe superlattices grown by molecular beam epitaxy. From their analysis, we conclude that an electron channeling mechanism, due to strong specular reflection of the minority spin carrier at the Au/Fe interfaces, is responsible for the high conductivity in the (100) superlattices.

  4. Evidence from d+Au measurements for final-state suppression of high-p(T) hadrons in Au+Au collisions at RHIC.

    PubMed

    Adams, J; Adler, C; Aggarwal, M M; Ahammed, Z; Amonett, J; Anderson, B D; Anderson, M; Arkhipkin, D; Averichev, G S; Badyal, S K; Balewski, J; Barannikova, O; Barnby, L S; Baudot, J; Bekele, S; Belaga, V V; Bellwied, R; Berger, J; Bezverkhny, B I; Bhardwaj, S; Bhaskar, P; Bhati, A K; Bichsel, H; Billmeier, A; Bland, L C; Blyth, C O; Bonner, B E; Botje, M; Boucham, A; Brandin, A; Bravar, A; Cadman, R V; Cai, X Z; Caines, H; Calderón de la Barca Sánchez, M; Carroll, J; Castillo, J; Castro, M; Cebra, D; Chaloupka, P; Chattopadhyay, S; Chen, H F; Chen, Y; Chernenko, S P; Cherney, M; Chikanian, A; Choi, B; Christie, W; Coffin, J P; Cormier, T M; Cramer, J G; Crawford, H J; Das, D; Das, S; Derevschikov, A A; Didenko, L; Dietel, T; Dong, X; Draper, J E; Du, F; Dubey, A K; Dunin, V B; Dunlop, J C; Dutta Majumdar, M R; Eckardt, V; Efimov, L G; Emelianov, V; Engelage, J; Eppley, G; Erazmus, B; Fachini, P; Faine, V; Faivre, J; Fatemi, R; Filimonov, K; Filip, P; Finch, E; Fisyak, Y; Flierl, D; Foley, K J; Fu, J; Gagliardi, C A; Ganti, M S; Gagunashvili, N; Gans, J; Gaudichet, L; Germain, M; Geurts, F; Ghazikhanian, V; Ghosh, P; Gonzalez, J E; Grachov, O; Grigoriev, V; Gronstal, S; Grosnick, D; Guedon, M; Guertin, S M; Gupta, A; Gushin, E; Gutierrez, T D; Hallman, T J; Hardtke, D; Harris, J W; Heinz, M; Henry, T W; Heppelmann, S; Herston, T; Hippolyte, B; Hirsch, A; Hjort, E; Hoffmann, G W; Horsley, M; Huang, H Z; Huang, S L; Humanic, T J; Igo, G; Ishihara, A; Jacobs, P; Jacobs, W W; Janik, M; Johnson, I; Jones, P G; Judd, E G; Kabana, S; Kaneta, M; Kaplan, M; Keane, D; Kiryluk, J; Kisiel, A; Klay, J; Klein, S R; Klyachko, A; Koetke, D D; Kollegger, T; Konstantinov, A S; Kopytine, M; Kotchenda, L; Kovalenko, A D; Kramer, M; Kravtsov, P; Krueger, K; Kuhn, C; Kulikov, A I; Kumar, A; Kunde, G J; Kunz, C L; Kutuev, R Kh; Kuznetsov, A A; Lamont, M A C; Landgraf, J M; Lange, S; Lansdell, C P; Lasiuk, B; Laue, F; Lauret, J; Lebedev, A; Lednický, R; Leontiev, V M; LeVine, M J; Li, C; Li, Q; Lindenbaum, S J; Lisa, M A; Liu, F; Liu, L; Liu, Z; Liu, Q J; Ljubicic, T; Llope, W J; Long, H; Longacre, R S; Lopez-Noriega, M; Love, W A; Ludlam, T; Lynn, D; Ma, J; Ma, Y G; Magestro, D; Mahajan, S; Mangotra, L K; Mahapatra, D P; Majka, R; Manweiler, R; Margetis, S; Markert, C; Martin, L; Marx, J; Matis, H S; Matulenko, Yu A; McShane, T S; Meissner, F; Melnick, Yu; Meschanin, A; Messer, M; Miller, M L; Milosevich, Z; Minaev, N G; Mironov, C; Mishra, D; Mitchell, J; Mohanty, B; Molnar, L; Moore, C F; Mora-Corral, M J; Morozov, V; de Moura, M M; Munhoz, M G; Nandi, B K; Nayak, S K; Nayak, T K; Nelson, J M; Nevski, P; Nikitin, V A; Nogach, L V; Norman, B; Nurushev, S B; Odyniec, G; Ogawa, A; Okorokov, V; Oldenburg, M; Olson, D; Paic, G; Pandey, S U; Pal, S K; Panebratsev, Y; Panitkin, S Y; Pavlinov, A I; Pawlak, T; Perevoztchikov, V; Peryt, W; Petrov, V A; Phatak, S C; Picha, R; Planinic, M; Pluta, J; Porile, N; Porter, J; Poskanzer, A M; Potekhin, M; Potrebenikova, E; Potukuchi, B V K S; Prindle, D; Pruneau, C; Putschke, J; Rai, G; Rakness, G; Raniwala, R; Raniwala, S; Ravel, O; Ray, R L; Razin, S V; Reichhold, D; Reid, J G; Renault, G; Retiere, F; Ridiger, A; Ritter, H G; Roberts, J B; Rogachevski, O V; Romero, J L; Rose, A; Roy, C; Ruan, L J; Rykov, V; Sahoo, R; Sakrejda, I; Salur, S; Sandweiss, J; Savin, I; Schambach, J; Scharenberg, R P; Schmitz, N; Schroeder, L S; Schweda, K; Seger, J; Seliverstov, D; Seyboth, P; Shahaliev, E; Shao, M; Sharma, M; Shestermanov, K E; Shimanskii, S S; Singaraju, R N; Simon, F; Skoro, G; Smirnov, N; Snellings, R; Sood, G; Sorensen, P; Sowinski, J; Spinka, H M; Srivastava, B; Stanislaus, S; Stock, R; Stolpovsky, A; Strikhanov, M; Stringfellow, B; Struck, C; Suaide, A A P; Sugarbaker, E; Suire, C; Sumbera, M; Surrow, B; Symons, T J M; Szanto de Toledo, A; Szarwas, P; Tai, A; Takahashi, J; Tang, A H; Thein, D; Thomas, J H; Tikhomirov, V; Tokarev, M; Tonjes, M B; Trainor, T A; Trentalange, S; Tribble, R E; Trivedi, M D; Trofimov, V; Tsai, O; Ullrich, T; Underwood, D G; Van Buren, G; VanderMolen, A M; Vasiliev, A N; Vasiliev, M; Vigdor, S E; Viyogi, Y P; Voloshin, S A; Waggoner, W; Wang, F; Wang, G; Wang, X L; Wang, Z M; Ward, H; Watson, J W; Wells, R; Westfall, G D; Whitten, C; Wieman, H; Willson, R; Wissink, S W; Witt, R; Wood, J; Wu, J; Xu, N; Xu, Z; Xu, Z Z; Yakutin, A E; Yamamoto, E; Yang, J; Yepes, P; Yurevich, V I; Zanevski, Y V; Zborovský, I; Zhang, H; Zhang, H Y; Zhang, W M; Zhang, Z P; Zołnierczuk, P A; Zoulkarneev, R; Zoulkarneeva, J; Zubarev, A N

    2003-08-15

    We report measurements of single-particle inclusive spectra and two-particle azimuthal distributions of charged hadrons at high transverse momentum (high p(T)) in minimum bias and central d+Au collisions at sqrt[s(NN)]=200 GeV. The inclusive yield is enhanced in d+Au collisions relative to binary-scaled p+p collisions, while the two-particle azimuthal distributions are very similar to those observed in p+p collisions. These results demonstrate that the strong suppression of the inclusive yield and back-to-back correlations at high p(T) previously observed in central Au+Au collisions are due to final-state interactions with the dense medium generated in such collisions. PMID:12935009

  5. Identification of Au–S complexes on Au(100)

    DOE PAGESBeta

    Walen, Holly; Liu, Da -Jiang; Oh, Junepyo; Yang, Hyun Jin; Kim, Yousoo; Thiel, P. A.

    2016-01-25

    In this study, using a combination of scanning tunneling microscopy and density functional theory (DFT) calculations, we have identified a set of related Au–S complexes that form on Au(100), when sulfur adsorbs and lifts the hexagonal surface reconstruction. The predominant complex is diamond-shaped with stoichiometry Au4S5. All of the complexes can be regarded as combinations of S–Au–S subunits. The complexes exist within, or at the edges of, p(2 × 2) sulfur islands that cover the unreconstructed Au regions, and are observed throughout the range of S coverage examined in this study, 0.009 to 0.12 monolayers. A qualitative model is developedmore » which incorporates competitive formation of complexes, Au rafts, and p(2 × 2) sulfur islands, as Au atoms are released by the surface structure transformation.« less

  6. High-spin level scheme of {sup 183}Au

    SciTech Connect

    Song, L.T.; Zhou, X.H.; Zhang, Y. H.; Guo, Y. X.; Lei, X.G.; Zheng, Y.; Liu, M.L.; De Angelis, G.; Marginean, N.; Gadea, A.; Napoli, D.R.; Axiotis, M.; Rusu, C.; Martinez, T.

    2005-01-01

    High-spin states in {sup 183}Au have been studied experimentally using the {sup 159}Tb({sup 29}Si,5n){sup 183}Au reaction at a beam energy of 140 MeV. Three- or higherfold {gamma}-ray coincidences have been measured using the detector array of GASP. The level scheme of {sup 183}Au was revised and extended. A rotational band proposed as the unfavored signature branch of the {pi}i{sub 13/2} band has been observed for {sup 183}Au. Interaction properties between the two negative-signature bands of the {pi}h{sub 9/2}-{pi}f{sub 7/2} system have been discussed for the light odd-A Au nuclei.

  7. Electrical Transport Properties of Au-Doped Deoxyribonucleic Acid Molecules

    NASA Astrophysics Data System (ADS)

    Hwang, Jong Seung; Hong, Su Heon; Kim, Hyung Kwon; Kwon, Young Whan; Jin, Jung Il; Hwang, Sung Woo; Ahn, Doyeol

    2005-04-01

    Deoxyribonucleic acid (DNA) molecules were doped with Au atoms and their electrical transport properties were measured. The Au doping was carried out by incubating a mixture of HAuCl4\\cdot3H2O and DNA solutions. The binding of Au atoms to DNA bases was identified using Fourier transform infrared spectroscopy and X-ray photoemission spectroscopy. The Au-doped DNA molecules were deposited on nanoelectrodes and the presence of the molecules between the electrodes was determined by both scanning electron microscopy and atomic force microscopy. Measurement of the current-voltage characteristics showed that the Au-doped DNA molecules exhibited a higher conductivity than undoped DNA molecules. Detailed analysis of the chemical composition shows that there is a strong possibility of reliably controlling the conductivity of DNA molecules using this method.

  8. High Transverse Momentum {eta} Meson Production in p+p,d+Au and Au+Au Collisions at sqrt(sNN) = 200 GeV

    SciTech Connect

    Adler, S. S.; Awes, Terry C; Batsouli, Sotiria; Cianciolo, Vince; Efremenko, Yuri; Plasil, F; Read Jr, Kenneth F; Silvermyr, David O; Sorensen, Soren P; Stankus, Paul W; Young, Glenn R; Zhang, Chun; PHENIX, Collaboration

    2007-01-01

    Inclusive transverse momentum spectra of {eta} mesons in the range p{sub T}{approx}2-12 GeV/c have been measured at midrapidity (|{eta}|<0.35) by the PHENIX experiment at RHIC in p+p,d+Au, and Au+Au collisions at {radical}R{sub NN}=200 GeV. The eta mesons are reconstructed through their {eta}{yields}{gamma} {gamma} channel for the three colliding systems as well as through the {eta}{yields}{pi}{sup 0}{pi}{sup +}{pi}{sup -} decay mode in p+p and d+Au collisions. The nuclear modification factor in d+Au collisions, RdAu(p{sub T}){approx}1.0-1.1, suggests at most only modest pT broadening ('Cronin enhancement'). In central Au+Au reactions, the eta yields are significantly suppressed, with RAuAu(p{sub T}){approx}0.2. The ratio of {eta} to {pi}{sup 0} yields is approximately constant as a function of pT for the three colliding systems in agreement with the high-pT world average of R{sub {eta}}/{pi}{sup 0}{approx}0.5 in hadron-hadron, hadron-nucleus, and nucleus-nucleus collisions for a wide range of center-of-mass energies {radical}R{sub NN}{approx}3-1800 GeV as well as, for high scaled momentum xp, in e{sup +}e{sup -} annihilations at {radical}R=91.2 GeV. These results are consistent with a scenario where high-pT eta production in nuclear collisions at the Relativistic Heavy Ion Collider is largely unaffected by initial-state effects but where light-quark mesons ({pi}{sup 0},{eta}) are equally suppressed due to final-state interactions of the parent partons in the dense medium produced in Au+Au reactions.

  9. Azimuthal Anisotropy in U +U and Au +Au Collisions at RHIC

    NASA Astrophysics Data System (ADS)

    Adamczyk, L.; Adkins, J. K.; Agakishiev, G.; Aggarwal, M. M.; Ahammed, Z.; Alekseev, I.; Alford, J.; Aparin, A.; Arkhipkin, D.; Aschenauer, E. C.; Averichev, G. S.; Banerjee, A.; Bellwied, R.; Bhasin, A.; Bhati, A. K.; Bhattarai, P.; Bielcik, J.; Bielcikova, J.; Bland, L. C.; Bordyuzhin, I. G.; Bouchet, J.; Brandin, A. V.; Bunzarov, I.; Burton, T. P.; 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, J. H.; Chen, X.; 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, H. Z.; Huang, B.; Huang, X.; Huck, P.; Humanic, T. J.; Igo, G.; Jacobs, W. W.; Jang, H.; Jiang, K.; Judd, E. G.; Kabana, S.; Kalinkin, D.; Kang, K.; Kauder, K.; Ke, H. W.; Keane, D.; Kechechyan, A.; Khan, Z. H.; Kikola, D. P.; Kisel, I.; Kisiel, A.; Koetke, D. D.; Kollegger, T.; Kosarzewski, L. K.; 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.; Li, W.; Li, Y.; Li, C.; Li, Z. M.; Li, X.; Li, X.; Lisa, M. A.; Liu, F.; Ljubicic, T.; Llope, W. J.; Lomnitz, M.; Longacre, R. S.; Luo, X.; Ma, L.; Ma, R.; Ma, Y. G.; Ma, G. L.; Magdy, N.; Majka, R.; Manion, A.; Margetis, S.; Markert, C.; Masui, H.; Matis, H. S.; McDonald, D.; Meehan, K.; Minaev, N. G.; Mioduszewski, S.; Mohanty, B.; Mondal, M. M.; Morozov, D. A.; Mustafa, M. K.; Nandi, B. K.; Nasim, Md.; Nayak, T. K.; Nigmatkulov, G.; Nogach, L. V.; Noh, S. Y.; Novak, J.; Nurushev, S. B.; Odyniec, G.; Ogawa, A.; Oh, K.; Okorokov, V.; Olvitt, D. L.; Page, B. S.; Pak, R.; Pan, Y. X.; Pandit, Y.; Panebratsev, Y.; Pawlik, B.; Pei, H.; Perkins, C.; Peterson, A.; Pile, P.; Planinic, M.; Pluta, J.; Poljak, N.; Poniatowska, K.; Porter, J.; Posik, M.; Poskanzer, A. M.; Pruthi, N. K.; Putschke, J.; Qiu, H.; Quintero, A.; Ramachandran, S.; Raniwala, S.; Raniwala, R.; 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.; Skoby, M. J.; Smirnov, D.; Smirnov, N.; Song, L.; Sorensen, P.; Spinka, H. M.; Srivastava, B.; Stanislaus, T. D. S.; Stepanov, M.; Stock, R.; Strikhanov, M.; Stringfellow, B.; Sumbera, M.; Summa, B. J.; Sun, X.; Sun, X. M.; Sun, Z.; Sun, Y.; Surrow, B.; Svirida, D. N.; Szelezniak, M. A.; Tang, Z.; Tang, A. H.; Tarnowsky, T.; Tawfik, A. N.; Thomas, J. H.; Timmins, A. R.; Tlusty, D.; Tokarev, M.; Trentalange, S.; Tribble, R. E.; Tribedy, P.; Tripathy, S. K.; Trzeciak, B. A.; 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.; Videbaek, F.; Viyogi, Y. P.; Vokal, S.; Voloshin, S. A.; Vossen, A.; Wang, F.; Wang, Y.; Wang, H.; Wang, J. S.; Wang, Y.; Wang, G.; Webb, G.; Webb, J. C.; Wen, L.; Westfall, G. D.; Wieman, H.; Wissink, S. W.; Witt, R.; Wu, Y. F.; Xiao, Z.; Xie, W.; Xin, K.; Xu, Y. F.; Xu, N.; Xu, Z.; Xu, Q. H.; Xu, H.; Yang, Y.; Yang, Y.; Yang, C.; Yang, S.; Yang, Q.; Ye, Z.; Yepes, P.; Yi, L.; Yip, K.; Yoo, I.-K.; Yu, N.; Zbroszczyk, H.; Zha, W.; Zhang, X. P.; Zhang, J. B.; Zhang, J.; Zhang, Z.; Zhang, S.; Zhang, Y.; Zhang, J. L.; Zhao, F.; Zhao, J.; Zhong, C.; Zhou, L.; Zhu, X.; Zoulkarneeva, Y.; Zyzak, M.; STAR Collaboration

    2015-11-01

    Collisions between prolate uranium nuclei are used to study how particle production and azimuthal anisotropies depend on initial geometry in heavy-ion collisions. We report the two- and four-particle cumulants, v2{2 } and v2{4 }, for charged hadrons from U +U collisions at √{sNN }=193 GeV and Au +Au collisions at √{sNN}=200 GeV . Nearly fully overlapping collisions are selected based on the energy deposited by spectators in zero degree calorimeters (ZDCs). Within this sample, the observed dependence of v2{2 } on multiplicity demonstrates that ZDC information combined with multiplicity can preferentially select different overlap configurations in U +U collisions. We also show that v2 vs multiplicity can be better described by models, such as gluon saturation or quark participant models, that eliminate the dependence of the multiplicity on the number of binary nucleon-nucleon collisions.

  10. Local structure of disordered Au-Cu and Au-Ag alloys

    NASA Astrophysics Data System (ADS)

    Frenkel, A. I.; Machavariani, V. Sh.; Rubshtein, A.; Rosenberg, Yu.; Voronel, A.; Stern, E. A.

    2000-10-01

    X-ray-absorption fine structure (XAFS) and x-ray-diffraction (XRD) measurements of disordered alloys AuxCu1-x and Au0.5Ag0.5 prepared by melt spinning were performed. In the Au0.5Ag0.5 alloy, no significant local deviations of the atoms from the average fcc lattice were detected while in AuxCu1-x alloys, significant deviations of atoms from the average fcc lattice were found. Mean-square vibrations of the Cu-Cu distances revealed by the XAFS in AuxCu1-x alloys indicate the weakening of contact between Cu atoms in the dilute limit. Our computer simulation for AuxCu1-x clusters of 105 atoms reproduces the main features of both the XAFS and XRD data.

  11. Dynamic aperture calculation for the RHIC 2010 100 GeV Au-Au run lattices

    SciTech Connect

    Luo, Y.; Brown, K.; Fischer, W.; Ptitsyn, V.; Roser, T.; Schoefer, V.; Tepikian, S.; Trbojevic, D.

    2010-08-01

    In this note we summarize the dynamic aperture calculation with the 2010 RHIC 100 GeV Au-Au run lattices. This study was initiated to understand the observed large beam decay in the Yellow ring after rf re-bucketing in the beginning of this run. The off-line linear lattice models and the interaction region non-linearity models are used. The large beam decay in the Yellow ring after re-bucketing was eventually eliminated by lowering the Yellow tunes to 0.21 from 0.235 with {beta}* = 0.7m lattice. In this note we only focus on the numeric simulation instead of the beam experiments.

  12. Interpretation of the first data on central Au+Au collisions at

    SciTech Connect

    Jeon, Sangyong; Kapusta, Joseph

    2001-01-01

    We compare three semimicroscopic theories to the first data on particle production in central Au+Au collisions taken at RHIC by the PHOBOS Collaboration as well as to existing data on central Pb+Pb collisions taken at the SPS by the NA49 Collaboration. The Linear Extrapolation of Ultrarelativistic nucleon-nucleon Scattering to nucleus-nucleus collisions (LEXUS) represents the SPS data quite well but predicts too many particles at RHIC. The wounded nucleon model predicts too few particles at both the SPS and RHIC; the collective tube model predicts fewer particles still. This suggests a transition in the dynamics of particle production between s=17 and 56A GeV as one goes from the SPS to RHIC.

  13. Proton-antiproton suppression in 200A GeV Au-Au collisions

    NASA Astrophysics Data System (ADS)

    Renk, Thorsten; Eskola, Kari J.

    2007-08-01

    We discuss the measured nuclear suppression of p+p¯ production in 200A GeV Au-Au collisions at the Relativistic Heavy Ion Collider (RHIC) within radiative energy loss. For the Albino-Kniehl-Kramer (AKK) set of fragmentation functions, proton production is dominated by gluons, giving rise to the expectation that the nuclear suppression for p+p¯ should be stronger than for pions due to the stronger coupling of gluons to the quenching medium. Using a hydrodynamical description for the soft matter evolution, we show that this is indeed seen in the calculation. However, the expected suppression factors for pions and protons are sufficiently similar that a discrimination with present data is not possible. In the high pT region above 6 GeV where the contributions of hydrodynamics and recombination to hadron production are negligible, the model calculation is in good agreement with the data on p+p¯ suppression.

  14. Proton-antiproton suppression in 200A GeV Au-Au collisions

    SciTech Connect

    Renk, Thorsten; Eskola, Kari J.

    2007-08-15

    We discuss the measured nuclear suppression of p+p production in 200A GeV Au-Au collisions at the Relativistic Heavy Ion Collider (RHIC) within radiative energy loss. For the Albino-Kniehl-Kramer (AKK) set of fragmentation functions, proton production is dominated by gluons, giving rise to the expectation that the nuclear suppression for p+p should be stronger than for pions due to the stronger coupling of gluons to the quenching medium. Using a hydrodynamical description for the soft matter evolution, we show that this is indeed seen in the calculation. However, the expected suppression factors for pions and protons are sufficiently similar that a discrimination with present data is not possible. In the high p{sub T} region above 6 GeV where the contributions of hydrodynamics and recombination to hadron production are negligible, the model calculation is in good agreement with the data on p+p suppression.

  15. Study of Kaon Isospin Fluctuations in Au+Au Collisions at STAR

    NASA Astrophysics Data System (ADS)

    Rose, Andrew

    2002-10-01

    Recent theoretical studies have suggested that in heavy ion collisions the formation of disoriented chiral condensates (DCC) may result from the restoration and subsequent re-breaking of chiral symmetry. Searches for DCC have so far focused on the pion sector with little attention given to the Kaon sector. Recently however, Kapusta has suggested the observation of enhanced production of Ω and \\overlineΩ at s_NN = 17 GeV, in Pb+Pb collisions, can in part be explained by the production of many small strange DCC regions. Gavin and Kapusta have additionally shown that strange DCCs production may induce anomalous fluctuations of the Kaon total isospin. We present a statistical analysis of Kaon isospin fluctuations in Au+Au collisions at 130- and 200-GeV measured with the STAR apparatus. The analysis is based on the ν_dyn fluctuation measure which correlates the production of neutral and charged kaons.

  16. Steering epitaxial alignment of Au, Pd, and AuPd nanowire arrays by atom flux change.

    PubMed

    Yoo, Youngdong; Seo, Kwanyong; Han, Sol; Varadwaj, Kumar S K; Kim, Hyun You; Ryu, Ji Hoon; Lee, Hyuck Mo; Ahn, Jae Pyoung; Ihee, Hyotcherl; Kim, Bongsoo

    2010-02-10

    We have synthesized epitaxial Au, Pd, and AuPd nanowire arrays in vertical or horizontal alignment on a c-cut sapphire substrate. We show that the vertical and horizontal nanowire arrays grow from half-octahedral seeds by the correlations of the geometry and orientation of seed crystals with those of as-grown nanowires. The alignment of nanowires can be steered by changing the atom flux. At low atom deposition flux vertical nanowires grow, while at high atom flux horizontal nanowires grow. Similar vertical/horizontal epitaxial growth is also demonstrated on SrTiO(3) substrates. This orientation-steering mechanism is visualized by molecular dynamics simulations. PMID:20050692

  17. Strangeness Production in Au+Au Reactions at √ {SNN} = 62.4\\ GeV

    NASA Astrophysics Data System (ADS)

    Arsene, Ionut-Cristian

    The measurement of strangeness is a valuable tool for understanding the reaction mechanism of nuclear collisions since all the strange particles need to be created during the reaction. Also, strangeness enhancement is one of the predicted signals of the QGP. In the present work we will discuss the behaviour of the strangeness production (i.e. K/π ratio) with rapidity and baryo-chemical potential in Au+Au collisions at 62.4 A GeV. In this particular reaction, BRAHMS is able to identify particles over 3.5 rapidity units and thereby cover a wide range of bar {p}/p ratios, including the fragmentation region. We will show spectra and ratios of identified particles as a function of pT and rapidity.

  18. A comparative study of the Au + H2, Au+ + H2, and Au- + H2 systems: Potential energy surfaces and dynamics of reactive collisions

    NASA Astrophysics Data System (ADS)

    Dorta-Urra, Anaís; Zanchet, Alexandre; Roncero, Octavio; Aguado, Alfredo

    2015-04-01

    In order to study the Au- + H2 collision, a new global potential energy surface (PES) describing the ground electronic state of AuH 2- system is developed and compared with the PESs of the neutral [Zanchet et al., J. Chem. Phys. 132, 034301 (2010)] and cationic systems [Anaís et al., J. Chem. Phys. 135, 091102 (2011)]. We found that Au- - H2 presents a H-Au-H insertion minimum attributed to the stabilization of the LUMO 3b2 orbital, which can be considered as the preamble of the chemisorption well appearing in larger gold clusters. While the LUMO orbital is stabilized, the HOMO 6a1 is destabilized, creating a barrier at the geometry where the energy orbitals' curves are crossing. In the anion, this HOMO is doubly occupied, while in the neutral system is half-filled and completely empty in the cation, explaining the gradual disappearance of the well and the barrier as the number of electrons decreases. The cation presents a well in the entrance channel partially explained by electrostatic interactions. The three systems' reactions are highly endothermic, by 1.66, 2.79, and 3.23 eV for AuH, AuH+, and AuH- products, respectively. The reaction dynamics is studied using quasi-classical trajectory method for the three systems. The one corresponding to the anionic system is new in this work. Collision energies between 1.00 and 8.00 eV, measured for the cation, are in good agreement with the simulated cross section for the AuH+. It was also found that the total fragmentation, in three atoms, competes becoming dominant at sufficiently high energy. Here, we study the competition between the two different reaction pathways for the anionic, cationic, and neutral species, explaining the differences using a simple model based on the topology of the potential energy surfaces.

  19. Modeling the Accretion Structure of AU Mon

    NASA Astrophysics Data System (ADS)

    Atwood-Stone, Corwin; Miller, Brendan P.; Richards, Mercedes T.; Budaj, Ján; Peters, Geraldine J.

    2012-12-01

    AU Mon is a long-period (11.113 days) Algol-type binary system with a persistent accretion disk that is apparent as double-peaked Hα emission. We present previously unpublished optical spectra of AU Mon which were obtained over 20 years from 1991-2011 with dense orbital phase coverage. We utilize these data, along with archival UV spectra, to model the temperature and structure of the accretion disk and the gas stream. Synthetic spectral profiles for lines including Hα, Hβ, and the Al III and Si IV doublets were computed with the Shellspec program. The best match between the model spectra and the observations is obtained for an accretion disk of inner/outer radius 5.1/23 R ⊙, thickness of 5.2 R ⊙, density of 1.0 × 10-13 g cm-3, and maximum temperature of 14,000 K, along with a gas stream at a temperature of ~8000 K transferring ~2.4 × 10-9 M ⊙ yr-1. We show Hα Doppler tomograms of the velocity structure of the gas, constructed from difference profiles calculated through sequentially subtracting contributions from the stars and accretion structures. The tomograms provide independent support for the Shellspec modeling, while also illustrating that residual emission at sub-Keplerian velocities persists even after subtracting the disk and stream emission. Spectral variability in the Hα profile beyond that expected from either the orbital or the long-period cycle is present on both multi-week and multi-year timescales, and may reflect quasi-random changes in the mass transfer rate or the disk structure. Finally, a transient UV spectral absorption feature may be modeled as an occasional outflow launched from the vicinity of the disk-stream interaction region.

  20. From the ternary Eu(Au/In)2 and EuAu4(Au/In)2 with remarkable Au/In distributions to a new structure type: The gold-rich Eu5Au16(Au/In)6 structure

    SciTech Connect

    Steinberg, Simon; Card, Nathan; Mudring, Anja -Verena

    2015-08-13

    The ternary Eu(Au/In)2 (EuAu0.46In1.54(2)) (I), EuAu4(Au/In)2 (EuAu4+xIn2–x with x = 0.75(2) (II), 0.93(2), and 1.03(2)), and Eu5Au16(Au/In)6 (Eu5Au17.29In4.71(3)) (III) have been synthesized, and their structures were characterized by single-crystal X-ray diffraction. I and II crystallize with the CeCu2-type (Pearson Symbol oI12; Imma; Z = 4; a = 4.9018(4) Å; b = 7.8237(5) Å; c = 8.4457(5) Å) and the YbAl4Mo2-type (tI14; I4/mmm; Z = 2; a = 7.1612(7) Å; c = 5.5268(7) Å) and exhibit significant Au/In disorder. I is composed of an Au/In-mixed diamond-related host lattice encapsulating Eu atoms, while the structure of II features ribbons of distorted, squared Au8 prisms enclosing Eu, Au, and In atoms. Combination of these structural motifs leads to a new structure type as observed for Eu5Au16(Au/In)6 (Eu5Au17.29In4.71(3)) (oS108; Cmcm; Z = 4; a = 7.2283(4) Å; b = 9.0499(6) Å; c = 34.619(2) Å), which formally represents a one-dimensional intergrowth of the series EuAu2–“EuAu4In2”. The site preferences of the disordered Au/In positions in II were investigated for different hypothetical “EuAu4(Au/In)2” models using the projector-augmented wave method and indicate that these structures attempt to optimize the frequencies of the heteroatomic Au–In contacts. Furthermore, a chemical bonding analysis on two “EuAu5In” and “EuAu4In2” models employed the TB-LMTO-ASA method and reveals that the subtle interplay between the local atomic environments and the bond energies determines the structural and site preferences for these systems.

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

    NASA Astrophysics Data System (ADS)

    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.

  2. Organosulfur-functionalized Au, Pd, and Au-Pd nanoparticles on 1D silicon nanowire substrates: preparation and XAFS studies.

    PubMed

    Zhang, Peng; Zhou, Xingtai; Tang, Yuanhong; Sham, Tsun Kong

    2005-08-30

    A hybrid preparative method was developed to prepare organosulfur-functionalized Au nanoparticles (NPs) on silicon nanowires (SiNWs) by reacting HAuCl(4) with SiNW in the presence of thiol. A number of organosulfur molecules-dodecanethiol, hexanethiol, 1,6-hexanedithiol, and tiopronin-were used to functionalize the Au surface. Size-selected NPs ranging from 1.6 to 7.5 nm were obtained by varying the S/Au ratio and the concentration of HAuCl(4). This method was further extended to the preparation Pd and Pd-Au bimetallic NPs on SiNWs. The morphology of the metal nanostructures was examined by transmission electron microscopy (TEM) and high-resolution transmission electron microscopy (HRTEM). The local structure and bonding of the SiNW-supported metal nanostructures were studied using X-ray absorption fine structures (XAFS) [including both X-ray near-edge structures (XANES) and extended X-ray absorption fine structures (EXAFS)] at the Au L(3)-, Pd K-, S K-, and Si K-edges. It was also found that the annealing of the thiol-capped Au NPs up to 500 degrees C transforms the surface of the thiol-capped NPs to gold sulfide, as identified using Au L(3)- and S K-edge XANES. We also illustrate that this preparative approach can be used to form size-controllable Au NPs on carbon nanotubes. PMID:16114963

  3. {phi} meson production in Au + Au and p + p collisions at {radical}s{sub NN}=200 GeV

    SciTech Connect

    Adams, J.; Adler, C.; Aggarwal, M.M.; Ahammed, Z.; Amonett, J.; Anderson, B.D.; Arkhipkin, D.; Averichev, G.S.; Badyal, S.K.; Balewski, J.; Barannikova, O.; Barnby, L.S.; Baudot, J.; Bekele, S.; Belaga, V.V.; Bellwied, R.; Berger, J.; Bezverkhny, B.I.; Bhardwaj, S.; Bhati, A.K.; Bichsel, H.; Billmeier, A.; Bland, L.C.; Blyth, C.O.; Bonner, B.E.; Botje, M.; Boucham, A.; Brandin, A.; Bravar, A.; Cadman, R.V.; Cai, X.Z.; Caines, H.; Calderon de la Barca Sanchez, M.; Carroll, J.; Castillo, J.; Cebra, D.; Chaloupka, P.; Chattopadhyay, S.; Chen, H.F.; Chen, Y.; Chernenko, S.P.; Cherney, M.; Chikanian, A.; Christie, W.; Coffin, J.P.; Cormier, T.M.; Cramer, J.G.; Crawford, H.J.; Das, D.; Das, S.; Derevschikov, A.A.; Didenko, L.; Dietel, T.; Dong, W.J.; Dong, X.; Draper, J.E.; Du, F.; Dubey, A.K.; Dunin, V.B.; Dunlop, J.C.; Dutta Majumdar, M.R.; Eckardt, V.; Efimov, L.G.; Emelianov, V.; Engelage, J.; Eppley, G.; Erazmus, B.; Estienne, M.; Fachini, P.; Faine, V.; Faivre, J.; Fatemi, R.; Filimonov, K.; Filip, P.; Finch, E.; Fisyak, Y.; Flierl, D.; Foley, K.J.; Fu, J.; Gagliardi, C.A.; Gagunashvili, N.; Gans, J.; Ganti, M.S.; Gaudichet, L.; Germain, M.; Geurts, F.; Ghazikhanian, V.; Ghosh, P.; Gonzalez, J.E.; Grachov, O.; Grebenyuk, O.; Gronstal, S.; Grosnick, D.; Guedon, M.; Guertin, S.M.; Gupta, A.; Gutierrez, T.D.; Hallman, T.J.; Hamed, A.; Hardtke, D.; Harris, J.W.; Heinz, M.; Henry, T.W.; Heppelmann, S.; Hippolyte, B.; Hirsch, A.; Hjort, E.; Hoffmann, G.W.; Horsley, M.; Huang, H.Z.; Huang, S.L.; Hughes, E.; Humanic, T.J.; Igo, G.; Ishihara, A.; Jacobs, P.; Jacobs, W.W.; Janik, M.; Johnson, I.; Jones, P.G.; Judd, E.G.; Kabana, S.; Kaplan, M.; Keane, D.; Khodyrev; Kiryluk, J.; Kisiel, A.; Klay, J.; Klein, S.R.; Klyachko, A.; Koetke, D.D.; Kollegger, T.; Kopytine, S.M.; Kotchenda, L.; Kovalenko, A.D.; Kramer, M.; Kravtsov, P.; Kravstov, V.I.; Krueger, K.; Kuhn, C.; Kulikov, A.I.; Kumar, A.; Kunde, G.J.; Kunz, C.L.; Kutuev, R.Kh.; et al.

    2004-06-01

    We report the STAR measurement of {psi} meson production in Au + Au and p + p collisions at {radical}s{sub NN} = 200 GeV. Using the event mixing technique, the {psi} spectra and yields are obtained at midrapidity for five centrality bins in Au+Au collisions and for non-singly-diffractive p+p collisions. It is found that the {psi} transverse momentum distributions from Au+Au collisions are better fitted with a single-exponential while the p+p spectrum is better described by a double-exponential distribution. The measured nuclear modification factors indicate that {psi} production in central Au+Au collisions is suppressed relative to peripheral collisions when scaled by the number of binary collisions (). The systematics of versus centrality and the constant {psi}/K{sup -} ratio versus beam species, centrality, and collision energy rule out kaon coalescence as the dominant mechanism for {psi} production.

  4. CO Oxidation mechanism on CeO2-supported Au nanoclusters

    SciTech Connect

    Kim H. Y.; Henkelman, G.

    2013-09-08

    To reveal the richer chemistry of CO oxidation by CeO2 supported Au Nanoclusters(NCs)/Nanoparticles, we design Au13 and Au12 supported on a flat and a stepped-CeO2 model (Au/CeO2) and study various kinds of CO oxidation mechanisms at the Au-CeO2 interface and the Au NC as well.

  5. Stream dynamics between 1 AU and 2 AU: A detailed comparison of observations and theory

    NASA Technical Reports Server (NTRS)

    Burlaga, L. F.; Pizzo, V.; Lazarus, A.; Gazis, P. R.

    1984-01-01

    A radial alignment of three solar wind stream structures observed by IMP-7 and -8 (at 1.0 AU) and Voyager 1 and 2 (in the range 1.4 to 1.8 AU) in late 1977 is presented. It is demonstrated that several important aspects of the observed dynamical evolution can be both qualitatively and quantitatively described with a single-fluid 2-D MHD numerical model of quasi-steady corotating flow, including accurate prediction of: (1) the formation of a corotating shock pair at 1.75 AU in the case of a simple, quasi-steady stream; (2) the coalescence of the thermodynamic and magnetic structures associated with the compression regions of two neighboring, interacting, corotating streams; and (3) the dynamical destruction of a small (i.e., low velocity-amplitude, short spatial-scale) stream by its overtaking of a slower moving, high-density region associated with a preceding transient flow. The evolution of these flow systems is discussed in terms of the concepts of filtering and entrainment.

  6. Influence of contacts on charge collection in an Au/CdTe/Au detector: A Simulation

    SciTech Connect

    Franc, J.; James, R.; Grill, R.; KUBAT, J.; BELAS, E.; HOSCHL, P.; MORAVEC, P.; AND Praus, P.

    2010-12-01

    We report our simulations on the influence of contacts on charge collection in semi-insulating (CdZn)Te with Au contacts under radiation flux, employing simultaneous solutions of the drift-diffusion and Poisson equations. The type of the space charge and the distribution of the electric field in the Au/(CdZn)Te/Au structure at high fluxes reflect the combined influence of charge generated by band bending at the electrodes, and from photogenerated carriers trapped at deep levels. We show that the space charge originating from the latter approaches dominance at high fluxes while the influence of the contacts becomes negligible. The ratio of trapping and collection times at low fluxes strongly depends on band bending, due mainly to a change in the occupation of deep levels by injection or depletion from the contacts. Such dependence is weak at high fluxes; in this case, the space charge due to trapped carriers prevails over that formed due to band bending. These phenomena can cause the formation an electric-field minimum within the device (the pinch point), the position of which is influenced by the nature of the contacts. The field minimum can completely disappear or develop into a dead layer as band bending changes.

  7. Observation of D0 meson nuclear modifications in Au+Au collisions at sNN=200 GeV

    DOE PAGESBeta

    Adamczyk, L.; Adkins, J. K.; Agakishiev, G.; Aggarwal, M. M.; Ahammed, Z.; Alekseev, I.; Alford, J.; Anson, C. D.; Aparin, A.; Arkhipkin, D.; et al

    2014-09-30

    We report the first measurement of charmed-hadron (D0) production via the hadronic decay channel (D0→K-+π+) in Au+Au collisions at √sNN=200 GeV with the STAR experiment. The charm production cross section per nucleon-nucleon collision at midrapidity scales with the number of binary collisions, Nbin, from p+p to central Au+Au collisions. The D0 meson yields in central Au+Aucollisions are strongly suppressed compared to those in p+p scaled by Nbin, for transverse momenta pT>3 GeV/c, demonstrating significant energy loss of charm quarks in the hot and dense medium. An enhancement at intermediate pT is also observed. Model calculations including strong charm-medium interactions andmore » coalescence hadronization describe our measurements.« less

  8. Wafer-level Au-Au bonding in the 350-450 °C temperature range

    NASA Astrophysics Data System (ADS)

    Tofteberg, Hannah R.; Schjølberg-Henriksen, Kari; Fasting, Eivind J.; Moen, Alexander S.; Taklo, Maaike M. V.; Poppe, Erik U.; Simensen, Christian J.

    2014-08-01

    Metal thermocompression bonding is a hermetic wafer-level packaging technology that facilitates vertical integration and shrinks the area used for device sealing. In this paper, Au-Au bonding at 350, 400 and 450 °C has been investigated, bonding wafers with 1 µm Au on top of 200 nm TiW. Test Si laminates with device sealing frames of 100, 200, and 400 µm in width were realized. Bond strengths measured by pull tests ranged from 8 to 102 MPa and showed that the bond strength increased with higher bonding temperatures and decreased with increasing frame width. Effects of eutectic reactions, grain growth in the Au film and stress relaxation causing buckles in the TiW film were most pronounced at 450 °C and negligible at 350 °C. Bond temperature below the Au-Si eutectic temperature 363 °C is recommended.

  9. Electronic and geometric structures of Au30 clusters: a network of 2e-superatom Au cores protected by tridentate protecting motifs with u3-S

    NASA Astrophysics Data System (ADS)

    Tian, Zhimei; Cheng, Longjiu

    2015-12-01

    Density functional theory calculations have been performed to study the experimentally synthesized Au30S(SR)18 and two related Au30(SR)18 and Au30S2(SR)18 clusters. The patterns of thiolate ligands on the gold cores for the three thiolate-protected Au30 nanoclusters are on the basis of the ``divide and protect'' concept. A novel extended protecting motif with u3-S, S(Au2(SR)2)2AuSR, is discovered, which is termed the tridentate protecting motif. The Au cores of Au30S(SR)18, Au30(SR)18 and Au30S2(SR)18 clusters are Au17, Au20 and Au14, respectively. The superatom-network (SAN) model and the superatom complex (SAC) model are used to explain the chemical bonding patterns, which are verified by chemical bonding analysis based on the adaptive natural density partitioning (AdNDP) method and aromatic analysis on the basis of the nucleus-independent chemical shift (NICS) method. The Au17 core of the Au30S(SR)18 cluster can be viewed as a SAN of one Au6 superatom and four Au4 superatoms. The shape of the Au6 core is identical to that revealed in the recently synthesized Au18(SR)14 cluster. The Au20 core of the Au30(SR)18 cluster can be viewed as a SAN of two Au6 superatoms and four Au4 superatoms. The Au14 core of Au30S2(SR)18 can be regarded as a SAN of two pairs of two vertex-sharing Au4 superatoms. Meanwhile, the Au14 core is an 8e-superatom with 1S21P6 configuration. Our work may aid understanding and give new insights into the chemical synthesis of thiolate-protected Au clusters.Density functional theory calculations have been performed to study the experimentally synthesized Au30S(SR)18 and two related Au30(SR)18 and Au30S2(SR)18 clusters. The patterns of thiolate ligands on the gold cores for the three thiolate-protected Au30 nanoclusters are on the basis of the ``divide and protect'' concept. A novel extended protecting motif with u3-S, S(Au2(SR)2)2AuSR, is discovered, which is termed the tridentate protecting motif. The Au cores of Au30S(SR)18, Au30(SR)18 and Au30S

  10. Medium-sized Au40(SR)24 and Au52(SR)32 nanoclusters with distinct gold-kernel structures and spectroscopic features

    NASA Astrophysics Data System (ADS)

    Xu, Wen Wu; Li, Yadong; Gao, Yi; Zeng, Xiao Cheng

    2016-01-01

    We have analyzed the structures of two medium-sized thiolate-protected gold nanoparticles (RS-AuNPs) Au40(SR)24 and Au52(SR)32 and identified the distinct structural features in their Au kernels [Sci. Adv., 2015, 1, e1500425]. We find that both Au kernels of the Au40(SR)24 and Au52(SR)32 nanoclusters can be classified as interpenetrating cuboctahedra. Simulated X-ray diffraction patterns of the RS-AuNPs with the cuboctahedral kernel are collected and then compared with the X-ray diffraction patterns of the RS-AuNPs of two other prevailing Au-kernels identified from previous experiments, namely the Ino-decahedral kernel and icosahedral kernel. The distinct X-ray diffraction patterns of RS-AuNPs with the three different types of Au-kernels can be utilized as signature features for future studies of structures of RS-AuNPs. Moreover, the simulated UV/Vis absorption spectra and Kohn-Sham orbital energy-level diagrams are obtained for the Au40(SR)24 and Au52(SR)32, on the basis of time-dependent density functional theory computation. The extrapolated optical band-edges of Au40(SR)24 and Au52(SR)32 are 1.1 eV and 1.25 eV, respectively. The feature peaks in the UV/Vis absorption spectra of the two clusters can be attributed to the d --> sp electronic transition. Lastly, the catalytic activities of the Au40(SR)24 and Au52(SR)32 are examined using CO oxidation as a probe. Both medium-sized thiolate-protected gold clusters can serve as effective stand-alone nanocatalysts.We have analyzed the structures of two medium-sized thiolate-protected gold nanoparticles (RS-AuNPs) Au40(SR)24 and Au52(SR)32 and identified the distinct structural features in their Au kernels [Sci. Adv., 2015, 1, e1500425]. We find that both Au kernels of the Au40(SR)24 and Au52(SR)32 nanoclusters can be classified as interpenetrating cuboctahedra. Simulated X-ray diffraction patterns of the RS-AuNPs with the cuboctahedral kernel are collected and then compared with the X-ray diffraction patterns of the RS-Au

  11. Ge-Au eutectic bonding of Ge {100} single crystals

    NASA Astrophysics Data System (ADS)

    Knowlton, W. B.; Itoh, K. M.; Beeman, J. W.; Emes, J. H.; Loretto, D.; Haller, E. E.

    1993-11-01

    We present preliminary results on the eutectic bonding between two {100} Ge single crystal surfaces using thin films of Au ranging from 900Å/surface to 300Å/surface and Pd (10% the thickness of Au). Following bonding, plan view optical microscopy (OM) of the cleaved interface of samples with Au thicknesses ≤ 500Å/surface show a eutectic morphology more conducive to phonon transmission through the bond interface. High resolution transmission electron microscopy (HRTEM) cross sectional interface studies of a 300Å/surface Au sample show <100> epitaxial growth of Ge. In sections of the bond, lattice continuity of the Ge is apparent through the interface. TEM studies also reveal <110> heteroepitaxial growth of Au with a Au-Ge lattice mismatch of less than 2%. Eutectic bonds with 200Å/surface Au have been attained with characterization pending. An optical polishing technique for Ge has been optimized to insure intimate contact between the Ge surfaces prior to bonding. Interferometry analysis of the optically polished Ge surface shows that surface height fluctuations lie within ±150Å across an interval of 1mm. Characterization of phonon transmission through the interface is discussed with respect to low temperature detection of ballistic phonons.

  12. Enantiospecific adsorption of cysteine on a chiral Au34 cluster

    NASA Astrophysics Data System (ADS)

    Pelayo, José de Jesús; Valencia, Israel; Díaz, Gabriela; López-Lozano, Xóchitl; Garzón, Ignacio L.

    2015-12-01

    The interaction of biological molecules like chiral amino acids with chiral metal clusters is becoming an interesting and active field of research because of its potential impact in, for example, chiral molecular recognition phenomena. In particular, the enantiospecific adsorption (EA) of cysteine (Cys) on a chiral Au55 cluster was theoretically predicted a few years ago. In this work, we present theoretical results, based on density functional theory, of the EA of non-zwitterionic cysteine interacting with the C3-Au34 chiral cluster, which has been experimentally detected in gas phase, using trapped ion electron diffraction. Our results show that, indeed, the adsorption energy of the amino acid depends on which enantiomers participate in the formation Cys-Au34 chiral complex. EA was obtained in the adsorption modes where both the thiol, and the thiol-amino functional groups of Cys are adsorbed on low-coordinated sites of the metal cluster surface. Similarly to what was obtained for the Cys-Au55 chiral complex, in the present work, it is found that the EA is originated from the different strength and location of the bond between the COOH functional group and surface Au atoms of the Au34 chiral cluster. Calculations of the vibrational spectrum for the different Cys-Au34 diastereomeric complexes predict the existence of a vibro-enantiospecific effect, indicating that the vibrational frequencies of the adsorbed amino acid depend on its handedness.

  13. Exfoliation restacking route to Au nanoparticle-clay nanohybrids

    NASA Astrophysics Data System (ADS)

    Paek, Seung-Min; Jang, Jae-Up; Hwang, Seong-Ju; Choy, Jin-Ho

    2006-05-01

    A novel gold-pillared aluminosilicate (Au-PILC) were synthesized with positively charged gold nanoparticles capped by mercaptoammonium and exfoliated silicate layers. Gold nanoparticles were synthesized by NaBH4 reduction of AuCl4- in the presence of N,N,N-Trimethyl (11-mercaptoundecyl)ammonium (HS(CH2)11NMe3+) protecting ligand in an aqueous solution, and purified by dialysis. The resulting positively charged and water-soluble gold nanoparticles were hybridized with exfoliated silicate sheets by electrostatic interaction. The formation of Au clay hybrids could be easily confirmed by the powder X-ray diffraction with the increased basal spacing of clay upon insertion of Au nanoparticles. TEM image clearly revealed that the Au particles with an average size of 4 nm maintain their structure even after intercalation. The Au nanoparticles supported by clay matrix were found to be thermally more stable, suggesting that the Au nanoparticles were homogeneously protected with clay nanoplates. The present synthetic route could be further applicable to various hybrid systems between metal nanoparticles and clays.

  14. Theoretical studies of acrolein hydrogenation on Au20 nanoparticle

    NASA Astrophysics Data System (ADS)

    Li, Zhe; Chen, Zhao-Xu; He, Xiang; Kang, Guo-Jun

    2010-05-01

    Gold nanoparticles play a key role in catalytic processes. We investigated the kinetics of stepwise hydrogenation of acrolein on Au20 cluster model and compared with that on Au(110) surface. The rate-limiting step barrier of CC reduction is about 0.5 eV higher than that of CO hydrogenation on Au(110) surface. On Au20 nanoparticle, however, the energy barrier of the rate-determining step for CC hydrogenation turns out to be slightly lower than the value for the CO reduction. The selectivity difference on the two substrate models are attributed to different adsorption modes of acrolein: via the CC on Au20, compared to through both CC and CO on Au(110). The preference switch implies that the predicted selectivity of competitive hydrogenation depends on substrate model sensitively, and particles with more low-coordinated Au atoms than flat surfaces are favorable for CC hydrogenation, which is in agreement with experimental result.

  15. First principles calculations of the optical and plasmonic response of Au alloys and intermetallic compounds

    NASA Astrophysics Data System (ADS)

    Keast, V. J.; Barnett, R. L.; Cortie, M. B.

    2014-07-01

    Pure Au is widely used in plasmonic applications even though its use is compromised by significant losses due to damping. There are some elements that are less lossy than Au (e.g. Ag or Al) but they will normally oxidize or corrode under ambient conditions. Here we examine whether alloying Au with a second element would be beneficial for plasmonic applications. In order to evaluate potential alternatives to pure Au, the density of states (DOS), dielectric function and plasmon quality factor have been calculated for alloys and compounds of Au with Al, Cd, Mg, Pd, Pt, Sn, Ti, Zn and Zr. Substitutional alloying of Au with Al, Cd, Mg and Zn was found to slightly improve the plasmonic response. Of the large number of intermetallic compounds studied, only AuAl2, Au3Cd, AuMg, AuCd and AuZn were found to be suitable for plasmonic applications.

  16. AuScope VLBI Project and Hobart 26-m Antenna

    NASA Technical Reports Server (NTRS)

    Lovell, Jim; Dickey, John; Reid, Brett; McCallum, Jamie; Shabala, Stas; Watson, Christopher; Ellingsen, Simon; Memin, Anthony

    2013-01-01

    This is a report on the activities carried out at the three AuScope VLBI observatories and the Hobart 26-m antenna. In 2012 the three AuScope 12-m antennas at Hobart (Hb), Katherine (Ke), and Yarragadee (Yg) completed their first full year of operations as an array. The Hobart 26-m antenna (Ho) continued to make a contribution to IVS, providing overlap with the Hb time series. In total the AuScope antennas and the Hobart 26 m observed for 146 antenna days in 2012. In this report we also briefly highlight our research activities during 2012 and our plans for 2013.

  17. Au plasmonics in a WS{sub 2}-Au-CuInS{sub 2} photocatalyst for significantly enhanced hydrogen generation

    SciTech Connect

    Cheng, Zhongzhou; Wang, Zhenxing E-mail: hej@nanoctr.cn; Shifa, Tofik Ahmed; Wang, Fengmei; Zhan, Xueying; Xu, Kai; He, Jun E-mail: hej@nanoctr.cn; Liu, Quanlin

    2015-11-30

    Promoting the activities of photocatalysts is still the critical challenge in H{sub 2} generation area. Here, a Au plasmon enhanced photocatalyst of WS{sub 2}-Au-CuInS{sub 2} is developed by inserting Au nanoparticles between WS{sub 2} nanotubes and CuInS{sub 2} (CIS) nanoparticles. Due to the localized surface plasmonic resonance properties from Au nanoparticles, WS{sub 2}-Au-CIS shows the best performance as compared to Au-CIS, CIS, WS{sub 2}-CIS, CIS-Au, WS{sub 2}-Au, and WS{sub 2}-CIS-Au. The surface plasmonic resonance effects dramatically intensify the absorption of visible light and help to inject hot electrons into the semiconductors. Our findings open up an efficient method to optimize the type-II structures for photocatalytic water splitting.

  18. Corrigendum to “Suppression of Υ production in d+Au and Au+Au collisions at √ SNN = 200 GeV" [Phys. Lett. B 735 (2014) 127-137

    DOE PAGESBeta

    Adamczyk, L.

    2015-04-01

    We report measurements of Υ meson production in p + p, d + Au, and Au+Au collisions using the STAR detector at RHIC. We compare the Υ yield to the measured cross section in p + p collisions in order to quantify any modifications of the yield in cold nuclear matter using d + Au data and in hot nuclear matter using Au+Au data separated into three centrality classes. Our p + p measurement is based on three times the statistics of our previous result. We obtain a nuclear modification factor for Upsilon (1S + 2S + 3S) in themore » rapidity range |y| < 1 in d + Au collisions of RdAu = 0.79 ± 0.24(stat.) ± 0.03(syst.) ± 0.10(p + p syst.). A comparison with models including shadowing and initial state parton energy loss indicates the presence of additional cold-nuclear matter suppression. Similarly, in the top 10% most-central Au + Au collisions, we measure a nuclear modification factor of R AA = 0.49 ±0.1(stat.) ±0.02(syst.) ±0.06(p + p syst.), which is a larger suppression factor than that seen in cold nuclear matter. Our results are consistent with complete suppression of excited-state Upsilon mesons in Au + Au collisions. The additional suppression in Au + Au is consistent with the level expected in model calculations that include the presence of a hot, deconfined Quark–Gluon Plasma. However, understanding the suppression seen in d + Au is still needed before any definitive statements about the nature of the suppression in Au + Au can be made.« less

  19. Corrigendum to “Suppression of Υ production in d+Au and Au+Au collisions at √ SNN = 200 GeV" [Phys. Lett. B 735 (2014) 127-137

    SciTech Connect

    Adamczyk, L.

    2015-04-01

    We report measurements of Υ meson production in p + p, d + Au, and Au+Au collisions using the STAR detector at RHIC. We compare the Υ yield to the measured cross section in p + p collisions in order to quantify any modifications of the yield in cold nuclear matter using d + Au data and in hot nuclear matter using Au+Au data separated into three centrality classes. Our p + p measurement is based on three times the statistics of our previous result. We obtain a nuclear modification factor for Upsilon (1S + 2S + 3S) in the rapidity range |y| < 1 in d + Au collisions of RdAu = 0.79 ± 0.24(stat.) ± 0.03(syst.) ± 0.10(p + p syst.). A comparison with models including shadowing and initial state parton energy loss indicates the presence of additional cold-nuclear matter suppression. Similarly, in the top 10% most-central Au + Au collisions, we measure a nuclear modification factor of R AA = 0.49 ±0.1(stat.) ±0.02(syst.) ±0.06(p + p syst.), which is a larger suppression factor than that seen in cold nuclear matter. Our results are consistent with complete suppression of excited-state Upsilon mesons in Au + Au collisions. The additional suppression in Au + Au is consistent with the level expected in model calculations that include the presence of a hot, deconfined Quark–Gluon Plasma. However, understanding the suppression seen in d + Au is still needed before any definitive statements about the nature of the suppression in Au + Au can be made.

  20. Transverse-energy distributions at midrapidity in p +p, d +Au, and Au +Au collisions at √sNN =62.4-200 GeV and implications for particle-production models

    NASA Astrophysics Data System (ADS)

    Adler, S. S.; Afanasiev, S.; Aidala, C.; Ajitanand, N. N.; Akiba, Y.; Al-Jamel, A.; Alexander, J.; Aoki, K.; Aphecetche, L.; Armendariz, R.; Aronson, S. H.; Averbeck, R.; Awes, T. C.; Azmoun, B.; Babintsev, V.; Baldisseri, A.; Barish, K. N.; Barnes, P. D.; Bassalleck, B.; Bathe, S.; Batsouli, S.; Baublis, V.; Bauer, F.; Bazilevsky, A.; Belikov, S.; Bennett, R.; Berdnikov, Y.; Bjorndal, M. T.; Boissevain, J. G.; Borel, H.; Boyle, K.; Brooks, M. L.; Brown, D. S.; Bruner, N.; Bucher, D.; Buesching, H.; Bumazhnov, V.; Bunce, G.; Burward-Hoy, J. M.; Butsyk, S.; Camard, X.; Campbell, S.; Chai, J.-S.; Chand, P.; Chang, W. C.; Chernichenko, S.; Chi, C. Y.; Chiba, J.; Chiu, M.; Choi, I. J.; Choudhury, R. K.; Chujo, T.; Cianciolo, V.; Cleven, C. R.; Cobigo, Y.; Cole, B. A.; Comets, M. P.; Constantin, P.; Csanád, M.; Csörgő, T.; Cussonneau, J. P.; Dahms, T.; Das, K.; David, G.; Deák, F.; Delagrange, H.; Denisov, A.; D'Enterria, D.; Deshpande, A.; Desmond, E. J.; Devismes, A.; Dietzsch, O.; Dion, A.; Drachenberg, J. L.; Drapier, O.; Drees, A.; Dubey, A. K.; Durum, A.; Dutta, D.; Dzhordzhadze, V.; Efremenko, Y. V.; Egdemir, J.; Enokizono, A.; En'yo, H.; Espagnon, B.; Esumi, S.; Fields, D. E.; Finck, C.; Fleuret, F.; Fokin, S. L.; Forestier, B.; Fox, B. D.; Fraenkel, Z.; Frantz, J. E.; Franz, A.; Frawley, A. D.; Fukao, Y.; Fung, S.-Y.; Gadrat, S.; Gastineau, F.; Germain, M.; Glenn, A.; Gonin, M.; Gosset, J.; Goto, Y.; Granier de Cassagnac, R.; Grau, N.; Greene, S. V.; Grosse Perdekamp, M.; Gunji, T.; Gustafsson, H.-Å.; Hachiya, T.; Hadj Henni, A.; Haggerty, J. S.; Hagiwara, M. N.; Hamagaki, H.; Hansen, A. G.; Harada, H.; Hartouni, E. P.; Haruna, K.; Harvey, M.; Haslum, E.; Hasuko, K.; Hayano, R.; He, X.; Heffner, M.; Hemmick, T. K.; Heuser, J. M.; Hidas, P.; Hiejima, H.; Hill, J. C.; Hobbs, R.; Holmes, M.; Holzmann, W.; Homma, K.; Hong, B.; Hoover, A.; Horaguchi, T.; Hur, M. G.; Ichihara, T.; Iinuma, H.; Ikonnikov, V. V.; Imai, K.; Inaba, M.; Inuzuka, M.; Isenhower, D.; Isenhower, L.; Ishihara, M.; Isobe, T.; Issah, M.; Isupov, A.; Jacak, B. V.; Jia, J.; Jin, J.; Jinnouchi, O.; Johnson, B. M.; Johnson, S. C.; Joo, K. S.; Jouan, D.; Kajihara, F.; Kametani, S.; Kamihara, N.; Kaneta, M.; Kang, J. H.; Katou, K.; Kawabata, T.; Kawagishi, T.; Kazantsev, A. V.; Kelly, S.; Khachaturov, B.; Khanzadeev, A.; Kikuchi, J.; Kim, D. J.; Kim, E.; Kim, E. J.; Kim, G.-B.; Kim, H. J.; Kim, Y.-S.; Kinney, E.; Kiss, Á.; Kistenev, E.; Kiyomichi, A.; Klein-Boesing, C.; Kobayashi, H.; Kochenda, L.; Kochetkov, V.; Kohara, R.; Komkov, B.; Konno, M.; Kotchetkov, D.; Kozlov, A.; Kroon, P. J.; Kuberg, C. H.; Kunde, G. J.; Kurihara, N.; Kurita, K.; Kweon, M. J.; Kwon, Y.; Kyle, G. S.; Lacey, R.; Lajoie, J. G.; Lebedev, A.; Leâ Bornec, Y.; Leckey, S.; Lee, D. M.; Lee, M. K.; Leitch, M. J.; Leite, M. A. L.; Li, X. H.; Lim, H.; Litvinenko, A.; Liu, M. X.; Maguire, C. F.; Makdisi, Y. I.; Malakhov, A.; Malik, M. D.; Manko, V. I.; Mao, Y.; Martinez, G.; Masui, H.; Matathias, F.; Matsumoto, T.; McCain, M. C.; McGaughey, P. L.; Miake, Y.; Miller, T. E.; Milov, A.; Mioduszewski, S.; Mishra, G. C.; Mitchell, J. T.; Mohanty, A. K.; Morrison, D. P.; Moss, J. M.; Moukhanova, T. V.; Mukhopadhyay, D.; Muniruzzaman, M.; Murata, J.; Nagamiya, S.; Nagata, Y.; Nagle, J. L.; Naglis, M.; Nakamura, T.; Newby, J.; Nguyen, M.; Norman, B. E.; Nyanin, A. S.; Nystrand, J.; O'Brien, E.; Ogilvie, C. A.; Ohnishi, H.; Ojha, I. D.; Okada, K.; Omiwade, O. O.; Oskarsson, A.; Otterlund, I.; Oyama, K.; Ozawa, K.; Pal, D.; Palounek, A. P. T.; Pantuev, V.; Papavassiliou, V.; Park, J.; Park, W. J.; Pate, S. F.; Pei, H.; Penev, V.; Peng, J.-C.; Pereira, H.; Peresedov, V.; Peressounko, D. Yu.; Pierson, A.; Pinkenburg, C.; Pisani, R. P.; Purschke, M. L.; Purwar, A. K.; Qu, H.; Qualls, J. M.; Rak, J.; Ravinovich, I.; Read, K. F.; Reuter, M.; Reygers, K.; Riabov, V.; Riabov, Y.; Roche, G.; Romana, A.; Rosati, M.; Rosendahl, S. S. E.; Rosnet, P.; Rukoyatkin, P.; Rykov, V. L.; Ryu, S. S.; Sahlmueller, B.; Saito, N.; Sakaguchi, T.; Sakai, S.; Samsonov, V.; Sanfratello, L.; Santo, R.; Sarsour, M.; Sato, H. D.; Sato, S.; Sawada, S.; Schutz, Y.; Semenov, V.; Seto, R.; Sharma, D.; Shea, T. K.; Shein, I.; Shibata, T.-A.; Shigaki, K.; Shimomura, M.; Shohjoh, T.; Shoji, K.; Sickles, A.; Silva, C. L.; Silvermyr, D.; Sim, K. S.; Singh, C. P.; Singh, V.; Skutnik, S.; Smith, W. C.; Soldatov, A.; Soltz, R. A.; Sondheim, W. E.; Sorensen, S. P.; Sourikova, I. V.; Staley, F.; Stankus, P. W.; Stenlund, E.; Stepanov, M.; Ster, A.; Stoll, S. P.; Sugitate, T.; Suire, C.; Sullivan, J. P.; Sziklai, J.; Tabaru, T.; Takagi, S.; Takagui, E. M.; Taketani, A.; Tanaka, K. H.; Tanaka, Y.; Tanida, K.; Tannenbaum, M. J.; Taranenko, A.; Tarján, P.; Thomas, T. L.; Togawa, M.; Tojo, J.; Torii, H.; Towell, R. S.; Tram, V.-N.; Tserruya, I.; Tsuchimoto, Y.; Tuli, S. K.; Tydesjö, H.; Tyurin, N.; Uam, T. J.; Vale, C.; Valle, H.; van Hecke, H. W.; Velkovska, J.; Velkovsky, M.; Vértesi, R.; Veszprémi, V.; Vinogradov, A. A.; Volkov, M. A.; Vznuzdaev, E.; Wagner, M.; Wang, X. R.; Watanabe, Y.; Wessels, J.; White, S. N.; Willis, N.; Winter, D.; Wohn, F. K.; Woody, C. L.; Wysocki, M.; Xie, W.; Yanovich, A.; Yokkaichi, S.; Young, G. R.; Younus, I.; Yushmanov, I. E.; Zajc, W. A.; Zaudtke, O.; Zhang, C.; Zhou, S.; Zimányi, J.; Zolin, L.; Zong, X.; Phenix Collaboration

    2014-04-01

    Measurements of the midrapidity transverse-energy distribution, dET/dη, are presented for p +p, d +Au, and Au +Au collisions at √sNN =200 GeV and additionally for Au +Au collisions at √sNN =62.4 and 130 GeV. The dET/dη distributions are first compared with the number of nucleon participants Npart, number of binary collisions Ncoll, and number of constituent-quark participants Nqp calculated from a Glauber model based on the nuclear geometry. For Au +Au, /Npart increases with Npart, while /Nqp is approximately constant for all three energies. This indicates that the two-component ansatz, dET/dη ∝(1-x)Npart/2+xNcoll, which was used to represent ET distributions, is simply a proxy for Nqp, and that the Ncoll term does not represent a hard-scattering component in ET distributions. The dET/dη distributions of Au +Au and d +Au are then calculated from the measured p +p ET distribution using two models that both reproduce the Au +Au data. However, while the number-of-constituent-quark-participant model agrees well with the d +Au data, the additive-quark model does not.

  1. From Superatomic Au25(SR)18- to Superatomic M@Au24(SR)18q Core-shell Clusters.

    SciTech Connect

    Jiang, Deen; Dai, Sheng

    2009-01-01

    Au{sub 25}(SR){sub 18}{sup -} belongs to a new type of superatom that features an icosahedral Au{sub 13} core-shell structure and a protective layer of six RS(Au-SR){sub 2} motifs. This superatom has a magic number of 8 free electrons that fully fill the 1s and 1p levels of the electron-shell model. By applying this superatom concept to the core-substitution chemistry of Au{sub 25}(SR){sub 18}{sup -}, we first scanned the periodic table for the potential core atom M by applying a simple rule derived from the 8-electron count and then optimized the selected candidates by density functional theory calculations to create many series of M{at}Au{sub 24}(SR){sub 18}{sup q} core-shell nanoclusters. We found that 16 elements from groups 1, 2, and 10-14 of the periodic table can maintain both electronic and geometric structures of the original Au{sub 25}(SR){sub 18}{sup -} magic cluster, indicating that the electron-counting rule based on the superatom concept is powerful in predicting viable M{at}Au{sub 24}(SR){sub 18}{sup q} clusters. Our work opens up a promising area for experimental exploration.

  2. Au and Ag/Au double-shells hollow nanoparticles with improved near infrared surface plasmon and photoluminescence properties.

    PubMed

    Ghosh Chaudhuri, Rajib; Paria, Santanu

    2016-01-01

    Metallic hollow nanoparticles have been continuously drawing researcher's attention because of their excellent improved performance compare to the spherical particles in catalysis, photonics, information storage, surface-enhanced Raman scattering, and sensors applications. In this article we demonstrate a novel route for the synthesis of single and double-shells Au and Ag/Au bimetallic hollow nanoparticles using elemental sulfur as a sacrificial core. We also investigate the optical properties of these new hollow particles and compare with that of pure spherical nanoparticles. The surface plasmon resonance spectra of solid Au, hollow single shell Au, and double shells Ag/Au nanoparticles show that there is gradual shifting of Au peak position towards the higher wavelengths for these three nanoparticles respectively. A similar observation was also found for photoluminescence spectra. In case of double-shells Ag/Au hollow nanoparticles the emission spectrum shifts towards the NIR region with significant higher intensity, which is beneficial for in vivo biomedical applications of these particles.

  3. Gold surfaces and nanoparticles are protected by Au(0)-thiyl species and are destroyed when Au(I)-thiolates form.

    PubMed

    Reimers, Jeffrey R; Ford, Michael J; Halder, Arnab; Ulstrup, Jens; Hush, Noel S

    2016-03-15

    The synthetic chemistry and spectroscopy of sulfur-protected gold surfaces and nanoparticles is analyzed, indicating that the electronic structure of the interface is Au(0)-thiyl, with Au(I)-thiolates identified as high-energy excited surface states. Density-functional theory indicates that it is the noble character of gold and nanoparticle surfaces that destabilizes Au(I)-thiolates. Bonding results from large van der Waals forces, influenced by covalent bonding induced through s-d hybridization and charge polarization effects that perturbatively mix in some Au(I)-thiolate character. A simple method for quantifying these contributions is presented, revealing that a driving force for nanoparticle growth is nobleization, minimizing Au(I)-thiolate involvement. Predictions that Brust-Schiffrin reactions involve thiolate anion intermediates are verified spectroscopically, establishing a key feature needed to understand nanoparticle growth. Mixing of preprepared Au(I) and thiolate reactants always produces Au(I)-thiolate thin films or compounds rather than monolayers. Smooth links to O, Se, Te, C, and N linker chemistry are established.

  4. Design and Preparation of Supported Au Catalyst with Enhanced Catalytic Activities by Rationally Positioning Au Nanoparticles on Anatase.

    PubMed

    Wang, Liang; Wang, Hong; Rice, Andrew E; Zhang, Wei; Li, Xiaokun; Chen, Mingshu; Meng, Xiangju; Lewis, James P; Xiao, Feng-Shou

    2015-06-18

    A synergistic effect between individual components is crucial for increasing the activity of metal/metal oxide catalysts. The greatest challenge is how to control the synergistic effect to obtain enhanced catalytic performance. Through density functional theory calculations of model Au/TiO2 catalysts, it is suggested that there is strong interaction between Au nanoparticles and Ti species at the edge/corner sites of anatase, which is favorable for the formation of stable oxygen vacancies. Motivated by this theoretical analysis, we have rationally prepared Au nanoparticles attached to edge/corner sites of anatase support (Au/TiO2-EC), confirmed by their HR-TEM images. As expected, this strong interaction is well characterized by Raman, UV-visible, and XPS techniques. Very interestingly, compared with conventional Au catalysts, Au/TiO2-EC exhibits superior catalytic activity in the oxidations using O2. Our approach to controlling Au nanoparticle positioning on anatase to obtain enhanced catalytic activity offers an efficient strategy for developing more novel supported metal catalysts.

  5. XRD analysis on ZnO and Au film crystal orientation in ZnO/Au/SiO2 structure

    NASA Astrophysics Data System (ADS)

    Qin, Huibin; Yu, Hong; Chen, Yunxang

    2000-05-01

    The orientation of the Zn/Au/Si structure was examined by XRD. The experiment showed that the ZnO/Au/Si films deposited by magnetron sputtering were possessed of a preferred orientation in C axis perpendicular to the film surface. The (111) of Au film was possessed of a preferred <111> orientation which was perpendicular to the film surface also. The XRD (theta) approximately 2 (theta) scan irradiated that there were only (001) peaks in excellent orientated ZnO films. The rock cure scan demonstrated that the C axis of ZnO film was not exactly perpendicular to the surface, the angular divergence was about 2 degree(s), and the space divergence angle about 1.5 degree(s). Expert the (kkk) main peaks of Au film there were weak diffraction peaks, such as (002), (022), and (311) peaks. The phenomena indicated that in Au film there was not only (111) plane in parallel to the surface of substrate. As there was only 12% dis-matching between Au (111) and ZnO (001), the Au (111) oriented film was facilitated for the ZnO (001) orientation in C axis and deposing parameters adjustment.

  6. Design and Preparation of Supported Au Catalyst with Enhanced Catalytic Activities by Rationally Positioning Au Nanoparticles on Anatase.

    PubMed

    Wang, Liang; Wang, Hong; Rice, Andrew E; Zhang, Wei; Li, Xiaokun; Chen, Mingshu; Meng, Xiangju; Lewis, James P; Xiao, Feng-Shou

    2015-06-18

    A synergistic effect between individual components is crucial for increasing the activity of metal/metal oxide catalysts. The greatest challenge is how to control the synergistic effect to obtain enhanced catalytic performance. Through density functional theory calculations of model Au/TiO2 catalysts, it is suggested that there is strong interaction between Au nanoparticles and Ti species at the edge/corner sites of anatase, which is favorable for the formation of stable oxygen vacancies. Motivated by this theoretical analysis, we have rationally prepared Au nanoparticles attached to edge/corner sites of anatase support (Au/TiO2-EC), confirmed by their HR-TEM images. As expected, this strong interaction is well characterized by Raman, UV-visible, and XPS techniques. Very interestingly, compared with conventional Au catalysts, Au/TiO2-EC exhibits superior catalytic activity in the oxidations using O2. Our approach to controlling Au nanoparticle positioning on anatase to obtain enhanced catalytic activity offers an efficient strategy for developing more novel supported metal catalysts. PMID:26266615

  7. Characterization of Pt-Au and Ni-Au Clusters on TiO(2)(110)

    SciTech Connect

    Chen, D. A.; Mullins, David R; Ratliff, J. S.; He, Wei; Tenney, Samuel

    2011-01-01

    The surface composition and properties of Pt-Au and Ni-Au clusters on TiO{sub 2}(110) have been studied by scanning tunneling microscopy (STM), low energy ion scattering (LEIS) and soft X-ray photoelectron spectroscopy (sXPS). STM studies show that bimetallic clusters are formed during sequential deposition of the two metals, regardless of the order of deposition. At the 2 ML of Au/2 ML of Pt or Ni coverages studied here, the second metal contributes to the growth of existing clusters rather than forming new pure metal clusters. LEIS experiments demonstrate that the surfaces of the bimetallic clusters are almost 100% Au when 2 ML of Au is deposited on top of 2 ML of Pt or Ni. However, a much larger fraction of Pt or Ni (50 and 20%, respectively) remains at the surface when 2 ML of Pt or Ni is deposited on 2 ML of Au, most likely due to limited diffusion of atoms within the clusters at room temperature. According to sXPS investigations, the binding energies of the metals in the bimetallic clusters are shifted from those observed for pure metal clusters; the Pt(4f{sub 7/2}) and Ni(3p{sub 3/2}) peaks are shifted to lower binding energies while the position of the Au(4f{sub 7/2}) peak is dominated by surface core level shifts. Pure Pt clusters as well as 0.4 ML of Au on 2 ML of Pt clusters reduce the titania support upon encapsulation after annealing to 800 K, whereas 2 ML of Au on 2 ML of Pt clusters do not reduce titania, presumably because there is no Pt at the surface of the clusters. Pure Ni clusters are also known to become encapsulated upon heating, but the reduction of titania is much less extensive compared to that of pure Pt clusters.

  8. Characterization of Pt-Au and Ni-Au Clusters on TiO2(110)

    SciTech Connect

    S Tenney; W He; J Ratliff; D Mullins; D Chen

    2011-12-31

    The surface composition and properties of Pt-Au and Ni-Au clusters on TiO{sub 2}(110) have been studied by scanning tunneling microscopy (STM), low energy ion scattering (LEIS) and soft X-ray photoelectron spectroscopy (sXPS). STM studies show that bimetallic clusters are formed during sequential deposition of the two metals, regardless of the order of deposition. At the 2 ML of Au/2 ML of Pt or Ni coverages studied here, the second metal contributes to the growth of existing clusters rather than forming new pure metal clusters. LEIS experiments demonstrate that the surfaces of the bimetallic clusters are almost 100% Au when 2 ML of Au is deposited on top of 2 ML of Pt or Ni. However, a much larger fraction of Pt or Ni (50 and 20%, respectively) remains at the surface when 2 ML of Pt or Ni is deposited on 2 ML of Au, most likely due to limited diffusion of atoms within the clusters at room temperature. According to sXPS investigations, the binding energies of the metals in the bimetallic clusters are shifted from those observed for pure metal clusters; the Pt(4f{sub 7/2}) and Ni(3p{sub 3/2}) peaks are shifted to lower binding energies while the position of the Au(4f{sub 7/2}) peak is dominated by surface core level shifts. Pure Pt clusters as well as 0.4 ML of Au on 2 ML of Pt clusters reduce the titania support upon encapsulation after annealing to 800 K, whereas 2 ML of Au on 2 ML of Pt clusters do not reduce titania, presumably because there is no Pt at the surface of the clusters. Pure Ni clusters are also known to become encapsulated upon heating, but the reduction of titania is much less extensive compared to that of pure Pt clusters.

  9. Visible light photoactivity of TiO2 loaded with monometallic (Au or Pt) and bimetallic (Au/Pt) nanoparticles

    NASA Astrophysics Data System (ADS)

    Gołąbiewska, Anna; Lisowski, Wojciech; Jarek, Marcin; Nowaczyk, Grzegorz; Zielińska-Jurek, Anna; Zaleska, Adriana

    2014-10-01

    TiO2 modified with monometallic (Au or Pt) and bimetallic (Au/Pt) nanoparticles have been prepared using a water-in-oil microemulsion system (water/AOT/cyclohexane) followed by calcination step. The effect of metal ratio, reducing agent type (NaBH4 or N2H4), TiO2 matrix type (P-25, ST-01, TiO-5, TiO2 nanotubes or TiO2 obtained by TIP hydrolysis) as well as calcination temperature (from 350 to 650 °C) were systematically investigated. Obtained photocatalysts were characterized by UV-vis diffuse-reflectance spectroscopy (DRS), BET surface area measurements, scanning transmission microscopy (STEM), X-ray diffraction analysis (XRD), and X-ray photoelectron spectroscopy (XPS). Photocatalytic activity under visible light (λ > 420 nm) has been estimated in phenol degradation reaction in aqueous phase. The results showed that phenol degradation rate under visible light in the presence of TiO2 loaded with Au/Pt nanoparticles differed from 0.7 to 2.2 μmol dm-3 min-1 for samples prepared using different reducing agent. Sodium borohydride (NaBH4) favors formation of smaller Au/Pt nanoparticles and higher amount gold in Au/Pt is in the form of electronegative species (Auδ-) resulted in higher photoactivity. TiO2 obtained by TIP hydrolysis in microemulsion system seems to be the best support for Au/Pt nanoparticles from all among investigated matrix. It was also observed that enhancement of calcination temperature from 450 to 650 °C resulted in rapid drop of Au/Pt-TiO2 photoactivity under visible light due to surface area shrinkage, crystal structure change and probably change in Au/Pt nanoparticles morphology.

  10. Recherche de leptons lourds au LEP 2

    NASA Astrophysics Data System (ADS)

    Tafirout, Reda

    En 1989, la mise en opération de la première phase du LEP (le LEP 1), au CERN, a une Energie correspondant a la résonance du boson Z0, a permis d'étudier et de confirmer avec une grande précision le Modèle Standard des interactions électrofaibles. Malgré le succès remarquable de ce modèle à décrire toutes les données expérimentales recueillies jusqu'à ce jour en physique des hautes énergies, ce dernier laisse plusieurs questions sans réponse. Il n'explique pas entre autres pourquoi il n'y a que trois familles de particules dont le neutrino associé est léger et la hiérarchie des masses observées des fermions reste une énigme. Ici, nous nous intéressons à l'existence éventuelle de nouveaux fermions, tels que prédits par des extensions du Modèle Standard. Ces nouveaux fermions ont été recherches au LEP 1, mais en vain, et une limite inférieure sur leur masse d'environ MZ/2 a pu être imposée. La deuxième phase du LEP (le LEP 2) qui a débuté dans l'automne 1995 avec une énergie disponible de √s = 130, et 136 GeV, puis dans l'été 1996 a √s = 161 GeV a permis d'améliorer ces limites. Nous présentons ici la recherche de leptons lourds, neutres (N) et chargés (L+/-), effectuée à partir des données recueillies dans l'automne 1996 avec le détecteur de la collaboration OPAL au LEP 2, à des énergies au centre de masse de √s = 170 et 172 GeV. La luminosité totale intégrée fut de 10.3 pb-1. Un nouveau générateur, EXOTIC, conçu et développé a cette fin, a été utilise pour la simulation des échantillons d'événements Monte Carlo qui ont servi à comparer les données obtenues avec les prédictions théoriques. Plus spécifiquement, nous avons recherché le processus e+e- --> NN où N, pouvant être de type Dirac ou Majorana, se désintègre en un lepton léger standard (e, μ, ou τ) et un boson W+/- virtuel (W+/-*). Pour un N de type Dirac, une limite inférieure sur la masse à 95% de niveau de confiance est obtenue

  11. Evaluation of the Olympus AU-510 analyser.

    PubMed

    Farré, C; Velasco, J; Ramón, F

    1991-01-01

    The selective multitest Olympus AU-510 analyser was evaluated according to the recommendations of the Comision de Instrumentacion de la Sociedad Española de Quimica Clinica and the European Committee for Clinical Laboratory Standards. The evaluation was carried out in two stages: an examination of the analytical units and then an evaluation in routine work conditions. The operational characteristics of the system were also studied.THE FIRST STAGE INCLUDED A PHOTOMETRIC STUDY: dependent on the absorbance, the inaccuracy varies between +0.5% to -0.6% at 405 nm and from -5.6% to 10.6% at 340 nm; the imprecision ranges between -0.22% and 0.56% at 405 nm and between 0.09% and 2.74% at 340 nm. Linearity was acceptable, apart from a very low absorbance for NADH at 340 nm; and the imprecision of the serum sample pipetter was satisfactory.TWELVE SERUM ANALYTES WERE STUDIED UNDER ROUTINE CONDITIONS: glucose, urea urate, cholesterol, triglycerides, total bilirubin, creatinine, phosphate, iron, aspartate aminotransferase, alanine aminotransferase and gamma-glutamyl transferase.The within-run imprecision (CV%) ranged from 0.67% for phosphate to 2.89% for iron and the between-run imprecision from 0.97% for total bilirubin to 7.06% for iron. There was no carryover in a study of the serum sample pipetter. Carry-over studies with the reagent and sample pipetters shows some cross contamination in the iron assay.

  12. Activated Dissociation of HCl on Au(111).

    PubMed

    Shirhatti, Pranav R; Geweke, Jan; Steinsiek, Christoph; Bartels, Christof; Rahinov, Igor; Auerbach, Daniel J; Wodtke, Alec M

    2016-04-01

    We report zero-coverage reaction probabilities (S0) for HCl dissociative adsorption on Au(111) obtained by the seeded molecular beam hot-nozzle method. For measurements at normal incidence with mean translational energies ranging from 0.94 to 2.56 eV (nozzle temperatures 296 to 1060 K), S0 increased from 6 × 10(-6) to 2 × 10(-2). S0 also increased with increasing nozzle temperature for fixed incidence energy associated with the motion normal to the surface. Accounting for the influence of the vibrational state population and translational energy distributions in the incident beam, we are able to compare the experimental results to recent theoretical predictions. These calculations, performed employing 6-D quantum dynamics on an electronically adiabatic potential energy surface obtained using density functional theory at the level of the generalized gradient approximation and the static surface approximation, severely overestimate the reaction probabilities when compared with our experimental results. We discuss some possible reasons for this large disagreement. PMID:26990513

  13. Metanephrine neuroendocrine tumor marker detection by SERS using Au nanoparticle/Au film sandwich architecture.

    PubMed

    Boca, Sanda; Farcau, Cosmin; Baia, Monica; Astilean, Simion

    2016-02-01

    Neuroendocrine tumors, such as pheochromocytoma or paraganglioma, are dangerous tumors that constitute a potential threat for a large number of patients. Currently, the biochemical diagnosis of neuroendocrine tumors is based on measurement of the direct secretory products of the adrenomedullary-sympathetic system or of their metabolites, such as catecholamines or their metanephrine derivatives, from plasma or urine. The techniques used for analysis of plasma free metanephrines, i.e. high-performance liquid chromatography or high-performance liquid chromatography coupled with mass-spectrometry are technically-demanding and time consuming, which limit their availability. Here we demonstrate a simple, fast and low-cost method for detecting metanephrine by Surface Enhanced Raman Scattering (SERS). The protocol consists in using evaporation-induced self-assembly of gold (Au) nanoparticles incubated with the analyte, on planar gold films. The assembly process produces regions with a dense distribution of both inter-particle gaps and particle-film gaps. Finite-difference time-domain simulations confirm that both kinds of gaps are locations of enhanced electromagnetic fields resulting from inter-particle and particle-film plasmonic coupling, useful for SERS amplification. Metanephrine vibrational bands assignment was performed according to density functional theory calculations. Metanephrine metabolite was detected in liquid at concentration levels lower than previously reported for other similar metabolites. The obtained results demonstrate that the Au nanoparticle/Au film exhibits noticeable SERS amplification of the adsorbed metabolite and can be used in the design of efficient, stable SERS-active substrates for the detection and identification of specific tumor markers.

  14. Metanephrine neuroendocrine tumor marker detection by SERS using Au nanoparticle/Au film sandwich architecture.

    PubMed

    Boca, Sanda; Farcau, Cosmin; Baia, Monica; Astilean, Simion

    2016-02-01

    Neuroendocrine tumors, such as pheochromocytoma or paraganglioma, are dangerous tumors that constitute a potential threat for a large number of patients. Currently, the biochemical diagnosis of neuroendocrine tumors is based on measurement of the direct secretory products of the adrenomedullary-sympathetic system or of their metabolites, such as catecholamines or their metanephrine derivatives, from plasma or urine. The techniques used for analysis of plasma free metanephrines, i.e. high-performance liquid chromatography or high-performance liquid chromatography coupled with mass-spectrometry are technically-demanding and time consuming, which limit their availability. Here we demonstrate a simple, fast and low-cost method for detecting metanephrine by Surface Enhanced Raman Scattering (SERS). The protocol consists in using evaporation-induced self-assembly of gold (Au) nanoparticles incubated with the analyte, on planar gold films. The assembly process produces regions with a dense distribution of both inter-particle gaps and particle-film gaps. Finite-difference time-domain simulations confirm that both kinds of gaps are locations of enhanced electromagnetic fields resulting from inter-particle and particle-film plasmonic coupling, useful for SERS amplification. Metanephrine vibrational bands assignment was performed according to density functional theory calculations. Metanephrine metabolite was detected in liquid at concentration levels lower than previously reported for other similar metabolites. The obtained results demonstrate that the Au nanoparticle/Au film exhibits noticeable SERS amplification of the adsorbed metabolite and can be used in the design of efficient, stable SERS-active substrates for the detection and identification of specific tumor markers. PMID:26820563

  15. Heterostructured Au/Pd-M (M = Au, Pd, Pt) nanoparticles with compartmentalized composition, morphology, and electrocatalytic activity

    NASA Astrophysics Data System (ADS)

    Lutz, Patrick S.; Bae, In-Tae; Maye, Mathew M.

    2015-09-01

    The synthesis, processing, and galvanic exchange of three heterostructured nanoparticle systems is described. The surface accessibility and redox potential of a Au/Pd-Ag dumbbell nanoparticle, where a Au/Pd core/shell region, and a silver region make up the domains, was used to prepare the new nanostructures with controlled composition, morphology, and microstructure. Results indicate that the silver domain was particularly susceptible to galvanic displacement, and was exchanged to Au/Pd-M (M = Au, Pd, Pt). Interestingly, the dumbbell morphology remained after exchange, and the silver region was transformed to hollow, parachute, or concentric domains respectively. The morphology and microstructure change was visualized via TEM and HRTEM, and the composition changes were probed via STEM-EDS imaging and XPS. The electrocatalytic activity of the Au/Pd-M towards methanol oxidation was studied, with results indicating that the Au/Pd-Pt nanoparticles had high activity attributed to the porous nature of the platinum domains.The synthesis, processing, and galvanic exchange of three heterostructured nanoparticle systems is described. The surface accessibility and redox potential of a Au/Pd-Ag dumbbell nanoparticle, where a Au/Pd core/shell region, and a silver region make up the domains, was used to prepare the new nanostructures with controlled composition, morphology, and microstructure. Results indicate that the silver domain was particularly susceptible to galvanic displacement, and was exchanged to Au/Pd-M (M = Au, Pd, Pt). Interestingly, the dumbbell morphology remained after exchange, and the silver region was transformed to hollow, parachute, or concentric domains respectively. The morphology and microstructure change was visualized via TEM and HRTEM, and the composition changes were probed via STEM-EDS imaging and XPS. The electrocatalytic activity of the Au/Pd-M towards methanol oxidation was studied, with results indicating that the Au/Pd-Pt nanoparticles had

  16. Distributions of charged hadrons associated with high transverse momentum particles in pp and Au+Au collisions at sqrt[sNN]=200 GeV.

    PubMed

    Adams, J; Adler, C; Aggarwal, M M; Ahammed, Z; Amonett, J; Anderson, B D; Arkhipkin, D; Averichev, G S; Badyal, S K; Balewski, J; Barannikova, O; Barnby, L S; Baudot, J; Bekele, S; Belaga, V V; Bellwied, R; Berger, J; Bezverkhny, B I; Bhardwaj, S; Bhati, A K; Bichsel, H; Billmeier, A; Bland, L C; Blyth, C O; Bonner, B E; Botje, M; Boucham, A; Brandin, A; Bravar, A; Cadman, R V; Cai, X Z; Caines, H; Calderón de la Barca Sánchez, M; Carroll, J; Castillo, J; Cebra, D; Chaloupka, P; Chattopadhyay, S; Chen, H F; Chen, Y; Chernenko, S P; Cherney, M; Chikanian, A; Christie, W; Coffin, J P; Cormier, T M; Cramer, J G; Crawford, H J; Das, D; Das, S; Derevschikov, A A; Didenko, L; Dietel, T; Dong, W J; Dong, X; Draper, J E; Du, F; Dubey, A K; Dunin, V B; Dunlop, J C; Dutta Majumdar, M R; Eckardt, V; Efimov, L G; Emelianov, V; Engelage, J; Eppley, G; Erazmus, B; Estienne, M; Fachini, P; Faine, V; Faivre, J; Fatemi, R; Filimonov, K; Filip, P; Finch, E; Fisyak, Y; Flierl, D; Foley, K J; Fu, J; Gagliardi, C A; Gagunashvili, N; Gans, J; Ganti, M S; Gaudichet, L; Geurts, F; Ghazikhanian, V; Ghosh, P; Gonzalez, J E; Grachov, O; Grebenyuk, O; Gronstal, S; Grosnick, D; Guertin, S M; Gupta, A; Gutierrez, T D; Hallman, T J; Hamed, A; Hardtke, D; Harris, J W; Heinz, M; Henry, T W; Heppelmann, S; Herston, T; Hippolyte, B; Hirsch, A; Hjort, E; Hoffmann, G W; Horsley, M; Huang, H Z; Huang, S L; Hughes, E; Humanic, T J; Igo, G; Ishihara, A; Jacobs, P; Jacobs, W W; Janik, M; Jiang, H; Johnson, I; Jones, P G; Judd, E G; Kabana, S; Kaplan, M; Keane, D; Khodyrev, V Yu; Kiryluk, J; Kisiel, A; Klay, J; Klein, S R; Klyachko, A; Koetke, D D; Kollegger, T; Kopytine, M; Kotchenda, L; Kovalenko, A D; Kramer, M; Kravtsov, P; Kravtsov, V I; Krueger, K; Kuhn, C; Kulikov, A I; Kumar, A; Kunde, G J; Kunz, C L; Kutuev, R Kh; Kuznetsov, A A; Lamont, M A C; Landgraf, J M; Lange, S; Lasiuk, B; Laue, F; Lauret, J; Lebedev, A; Lednický, R; Levine, M J; Li, C; Li, Q; Lindenbaum, S J; Lisa, M A; Liu, F; Liu, L; Liu, Z; Liu, Q J; Ljubicic, T; Llope, W J; Long, H; Longacre, R S; Lopez-Noriega, M; Love, W A; Ludlam, T; Lynn, D; Ma, J; Ma, Y G; Magestro, D; Mahajan, S; Mangotra, L K; Mahapatra, D P; Majka, R; Manweiler, R; Margetis, S; Markert, C; Martin, L; Marx, J; Matis, H S; Matulenko, Yu A; McClain, C J; McShane, T S; Meissner, F; Melnick, Yu; Meschanin, A; Miller, M L; Milosevich, Z; Minaev, N G; Mironov, C; Mischke, A; Mishra, D; Mitchell, J; Mohanty, B; Molnar, L; Moore, C F; Mora-Corral, M J; Morozov, D A; Morozov, V; de Moura, M M; Munhoz, M G; Nandi, B K; Nayak, S K; Nayak, T K; Nelson, J M; Netrakanti, P K; Nikitin, V A; Nogach, L V; Norman, B; Nurushev, S B; Odyniec, G; Ogawa, A; Okorokov, V; Oldenburg, M; Olson, D; Paic, G; Pal, S K; Panebratsev, Y; Panitkin, S Y; Pavlinov, A I; Pawlak, T; Peitzmann, T; Perevoztchikov, V; Perkins, C; Peryt, W; Petrov, V A; Phatak, S C; Picha, R; Planinic, M; Pluta, J; Porile, N; Porter, J; Poskanzer, A M; Potekhin, M; Potrebenikova, E; Potukuchi, B V K S; Prindle, D; Pruneau, C; Putschke, J; Rai, G; Rakness, G; Raniwala, R; Raniwala, S; Ravel, O; Ray, R L; Razin, S V; Reichhold, D; Reid, J G; Renault, G; Retiere, F; Ridiger, A; Ritter, H G; Roberts, J B; Rogachevski, O V; Romero, J L; Rose, A; Roy, C; Ruan, L J; Sahoo, R; Sakrejda, I; Salur, S; Sandweiss, J; Savin, I; Schambach, J; Scharenberg, R P; Schmitz, N; Schroeder, L S; Schweda, K; Seger, J; Seyboth, P; Shahaliev, E; Shao, M; Shao, W; Sharma, M; Shestermanov, K E; Shimanskii, S S; Singaraju, R N; Simon, F; Skoro, G; Smirnov, N; Snellings, R; Sood, G; Sorensen, P; Sowinski, J; Speltz, J; Spinka, H M; Srivastava, B; Stanislaus, T D S; Stock, R; Stolpovsky, A; Strikhanov, M; Stringfellow, B; Struck, C; Suaide, A A P; Sugarbaker, E; Suire, C; Sumbera, M; Surrow, B; Symons, T J M; Szanto de Toledo, A; Szarwas, P; Tai, A; Takahashi, J; Tang, A H; Thein, D; Thomas, J H; Timoshenko, S; Tokarev, M; Tonjes, M B; Trainor, T A; Trentalange, S; Tribble, R E; Tsai, O; Ullrich, T; Underwood, D G; Van Buren, G; Vandermolen, A M; Varma, R; Vasilevski, I; Vasiliev, A N; Vernet, R; Vigdor, S E; Viyogi, Y P; Voloshin, S A; Vznuzdaev, M; Waggoner, W; Wang, F; Wang, G; Wang, G; Wang, X L; Wang, Y; Wang, Z M; Ward, H; Watson, J W; Webb, J C; Wells, R; Westfall, G D; Whitten, C; Wieman, H; Willson, R; Wissink, S W; Witt, R; Wood, J; Wu, J; Xu, N; Xu, Z; Xu, Z Z; Yamamoto, E; Yepes, P; Yurevich, V I; Yuting, B; Zanevski, Y V; Zhang, H; Zhang, W M; Zhang, Z P; Zhaomin, Z P; Zizong, Z P; Zołnierczuk, P A; Zoulkarneev, R; Zoulkarneeva, J; Zubarev, A N

    2005-10-01

    Charged hadrons in [EQUATION: SEE TEXT] associated with particles of [EQUATION: SEE TEXT] are reconstructed in pp and Au+Au collisions at sqrt[sNN]=200 GeV. The associated multiplicity and p magnitude sum are found to increase from pp to central Au+Au collisions. The associated p distributions, while similar in shape on the nearside, are significantly softened on the awayside in central Au+Au relative to pp and not much harder than that of inclusive hadrons. The results, consistent with jet quenching, suggest that the awayside fragments approach equilibration with the medium traversed. PMID:16241721

  17. Microwave synthesis of Au nanoparticles as promising SERS substrates

    NASA Astrophysics Data System (ADS)

    Wang, Lan; Feng, Shangyuan; Liu, Nenrong; Lei, Jinping; Lin, Hongxin; Sun, Liqing; Chen, Rong

    2012-11-01

    A novel method for rapidly synthesized Au colloidal under microwave irradiation was present in this paper. Size of the Au nanoparticles varied from 10 nm to 60 nm along with varying mol fractions by chloroauric acid solution reduced with sodium citrate. The prepared Au nanoparticles were characterized by transmission electron microscope (TEM) and ultraviolet-visible (UV-Vis) spectrophotometer. It is found that the nanoparticle size and shape are highly dependent on the reaction time and the molar ratios of the reducing agent. By the SERS measurements of R6G, 4-MBA and Crystal violet, this Au colloid is shown to be an excellent SERS substrate with good stability. As the fabrication process of this SERS substrate is simple and inexpensive, this method may be used in large-scale preparation of substrates that can serve as an ideal SERS substrate in biomedical application.

  18. γ decay from the quasicontinuum of Au,198197

    NASA Astrophysics Data System (ADS)

    Giacoppo, F.; Bello Garrote, F. L.; Bernstein, L. A.; Bleuel, D. L.; Firestone, R. B.; Görgen, A.; Guttormsen, M.; Hagen, T. W.; Klintefjord, M.; Koehler, P. E.; Larsen, A. C.; Nyhus, H. T.; Renstrøm, T.; Sahin, E.; Siem, S.; Tornyi, T.

    2015-05-01

    The average electromagnetic dipole response of levels in the quasicontinuum of Au,198197 has been measured using (3He,3He' ) and (d ,p ) reactions. The extracted γ -ray strength functions have been normalized according to three model assumptions for the nuclear spin distribution. An enhancement in the energy region Eγ=3.0 -6.5 MeV is observed for both isotopes. The E 1 component of such excess of strength is studied in detail for 198Au and is interpreted as the pygmy dipole resonance with an energy centroid of 5.9 (1 ) MeV and exhausts about 1 % of the total integrated strength. The pygmy dipole resonance is shown to have a significant impact on the calculated 197Au (n,γ ) 198Au cross section.

  19. Assembling Bare Au Nanoparticles at Positively Charged Templates

    PubMed Central

    Wang, Wenjie; Zhang, Honghu; Kuzmenko, Ivan; Mallapragada, Surya; Vaknin, David

    2016-01-01

    In-situ X-ray reflectivity (XRR) and grazing incidence X-ray small-angle scattering (GISAXS) reveal that unfunctionalized (bare) gold nanoparticles (AuNP) spontaneously adsorb to a cationic lipid template formed by a Langmuir monolayer of DPTAP (1,2-dihexadecanoyl-3-trimethylammonium-propane) at vapor/aqueous interfaces. Analysis of the XRR yields the electron density profile across the charged-interfaces along the surface normal showing the AuNPs assemble with vertical thickness comparable to the particle size. The GISAXS analysis indicates that the adsorbed mono-particle layer exhibits short-range in-plane correlations. By contrast, single-stranded DNA-functionalized AuNPs, while attracted to the positively charged surface (more efficiently with the addition of salt to the solution), display less in-plane regular packing compared to bare AuNPs. PMID:27225047

  20. Assembling Bare Au Nanoparticles at Positively Charged Templates

    NASA Astrophysics Data System (ADS)

    Wang, Wenjie; Zhang, Honghu; Kuzmenko, Ivan; Mallapragada, Surya; Vaknin, David

    2016-05-01

    In-situ X-ray reflectivity (XRR) and grazing incidence X-ray small-angle scattering (GISAXS) reveal that unfunctionalized (bare) gold nanoparticles (AuNP) spontaneously adsorb to a cationic lipid template formed by a Langmuir monolayer of DPTAP (1,2-dihexadecanoyl-3-trimethylammonium-propane) at vapor/aqueous interfaces. Analysis of the XRR yields the electron density profile across the charged-interfaces along the surface normal showing the AuNPs assemble with vertical thickness comparable to the particle size. The GISAXS analysis indicates that the adsorbed mono-particle layer exhibits short-range in-plane correlations. By contrast, single-stranded DNA-functionalized AuNPs, while attracted to the positively charged surface (more efficiently with the addition of salt to the solution), display less in-plane regular packing compared to bare AuNPs.

  1. Ethylene binding to Au/Cu alloy nanoparticles

    NASA Astrophysics Data System (ADS)

    Gammage, Michael D.; Stauffer, Shannon; Henkelman, Graeme; Becker, Michael F.; Keto, John W.; Kovar, Desiderio

    2016-11-01

    Weak chemisorption of ethylene has been shown to be an important characteristic in the use of metals for the separation of ethylene from ethane. Previously, density functional theory (DFT) has been used to predict the binding energies of various metals and alloys, with Ag having the lowest chemisorption energy amongst the metals and alloys studied. Here Au/Cu alloys are investigated by a combination of DFT calculations and experimental measurements. It is inferred from experiments that the binding energy between a Au/Cu alloy and ethylene is lower than to either of the pure metals, and DFT calculations confirm that this is the case when Au segregates to the particle surface. Implications of this work suggest that it may be possible to further tune the binding energy with ethylene by compositional and morphological control of films produced from Au-surface segregated alloys.

  2. Assembling Bare Au Nanoparticles at Positively Charged Templates

    DOE PAGESBeta

    Wang, Wenjie; Zhang, Honghu; Kuzmenko, Ivan; Mallapragada, Surya; Vaknin, David

    2016-05-26

    In-situ X-ray reflectivity (XRR) and grazing incidence X-ray small-angle scattering (GISAXS) reveal that unfunctionalized (bare) gold nanoparticles (AuNP) spontaneously adsorb to a cationic lipid template formed by a Langmuir monolayer of DPTAP (1,2-dihexadecanoyl-3-trimethylammonium-propane) at vapor/aqueous interfaces. Analysis of the XRR yields the electron density profile across the charged-interfaces along the surface normal showing the AuNPs assemble with vertical thickness comparable to the particle size. The GISAXS analysis indicates that the adsorbed mono-particle layer exhibits short-range in-plane correlations. By contrast, single-stranded DNA-functionalized AuNPs, while attracted to the positively charged surface (more efficiently with the addition of salt to the solution), displaymore » less in-plane regular packing compared to bare AuNPs.« less

  3. Dynamic features of rod-shaped Au nanoclusters

    NASA Astrophysics Data System (ADS)

    So, Woong Young; Das, Anindita; Wang, Shuxin; Zhao, Shuo; Byun, Hee Young; Lee, Dana; Kumar, Santosh; Jin, Rongchao; Peteanu, Linda A.

    2015-08-01

    Gold nanoclusters hold many potential applications such as biosensing and optics due to their emission characteristics, small size, and non-toxicity. However, their low quantum yields remain problematic for further applications, and their fluorescence mechanism is still unclear. To increase the low quantum yields, various methods have been performed: doping, tuning structures, and changing number of gold atoms. In the past, most characterizations have been performed on spherical shaped nanoclusters; in this paper, several characterizations of various rod-shaped Au nanoclusters specifically on Au25 are shown. It has been determined that the central gold atom in Au25 nano-rod is crucial in fluorescence. Furthermore, single molecule analysis of silver doped Au25 nano-rod revealed that it has more photo-stability than conjugated polymers and quantum dots.

  4. Melting curve of metals Cu, Ag and Au under pressure

    NASA Astrophysics Data System (ADS)

    Tam, Pham Dinh; Hoc, Nguyen Quang; Tinh, Bui Duc; Tan, Pham Duy

    2016-01-01

    In this paper, the dependence of the melting temperature of metals Cu, Ag and Au under pressure in the interval from 0 kbar to 40 kbar is studied by the statistical moment method (SMM). This dependence has the form of near linearity and the calculated slopes of melting curve are 3.9 for Cu, 5.7 for Ag and 6 for Au. These results are in good agreement with the experimental data.

  5. Formation, Migration, and Reactivity of Au-CO Complexes on Gold Surfaces.

    PubMed

    Wang, Jun; McEntee, Monica; Tang, Wenjie; Neurock, Matthew; Baddorf, Arthur P; Maksymovych, Petro; Yates, John T

    2016-02-10

    We report experimental as well as theoretical evidence that suggests Au-CO complex formation upon the exposure of CO to active sites (step edges and threading dislocations) on a Au(111) surface. Room-temperature scanning tunneling microscopy (STM), X-ray photoelectron spectroscopy, transmission infrared spectroscopy, and density functional theory calculations point to Au-CO complex formation and migration. Room-temperature STM of the Au(111) surface at CO pressures in the range from 10(-8) to 10(-4) Torr (dosage up to 10(6) langmuir) indicates Au atom extraction from dislocation sites of the herringbone reconstruction, mobile Au-CO complex formation and diffusion, and Au adatom cluster formation on both elbows and step edges on the Au surface. The formation and mobility of the Au-CO complex result from the reduced Au-Au bonding at elbows and step edges leading to stronger Au-CO bonding and to the formation of a more positively charged CO (CO(δ+)) on Au. Our studies indicate that the mobile Au-CO complex is involved in the Au nanoparticle formation and reactivity, and that the positive charge on CO increases due to the stronger adsorption of CO at Au sites with lower coordination numbers. PMID:26754257

  6. On the stability of AuFe alloy nanoparticles.

    PubMed

    Velasco, V; Pohl, D; Surrey, A; Bonatto-Minella, A; Hernando, A; Crespo, P; Rellinghaus, B

    2014-05-30

    AuFe nanoparticles with mean diameters d p  = 13.2 nm have been prepared by inert-gas condensation. Conventional and high-resolution transmission electron microscopy and energy-dispersive x-ray spectroscopy investigations show that the particles are mostly icosahedra. Scanning transmission electron microscopy-energy-dispersive x-ray spectroscopy and scanning transmission electron microscopy-electron energy-loss spectroscopy show that the as-grown particles exhibit a core-shell structure. The shell is mainly composed of an amorphous FeO layer. Although Fe and Au are immiscible in the bulk, the particle cores are found to be homogeneously mixed at the atomic level with a local composition of around Au84Fe16 (at.%). AuFe nanoparticles exhibit a complex magnetic structure in which the core behaves as a spin glass with a freezing temperature of 35 K, whereas the amorphous FeO shell behaves as a ferro-ferrimagnetic system. On annealing above 300 °C, the AuFe icosahedra phases separate into their elemental constituents. Hence the as-grown AuFe icosahedra are metastable, thereby implying that the bulk phase diagram also applies for nanoscopic materials.

  7. Rotating Au nanorod and nanowire driven by circularly polarized light.

    PubMed

    Liaw, Jiunn-Woei; Chen, Ying-Syuan; Kuo, Mao-Kuen

    2014-10-20

    The wavelength-dependent optical torques provided by a circularly polarized (CP) plane wave driving Au nanorod (NR) and nanowire (NW) to rotate constantly were studied theoretically. Using the multiple multipole method, the resultant torque in terms of Maxwell's stress tensor was analyzed. Numerical results show that the optical torque spectrum is in accordance with the absorption spectrum of Au NR/NW. Under the same fluence, the maximum optical torque occurs at the longitudinal surface plasmon resonance (LSPR) of Au NR/NW, accompanied by a severe plasmonic heating. The rotation direction of the light-driven NR/NW depends on the handedness of CP light. In contrast, the optical torque exerted on Au NR/NW illuminated by a linearly polarized light is null at LSPR. Due to the plasmonic effect, the optical torque on Au NR/NW by CP light is two orders of magnitude larger than that on a dielectric NR/NW of the same size. The steady-state rotation of NR/NW in water, resulting from the balance of optical torque and viscous torque, was also discussed. Our finding shed some light on manipulating a CP light-driven Au NR/NW as a rotating nanomotor for a variety of applications in optofluidics and biophysics.

  8. Structural and dynamical properties of liquid Al-Au alloys

    NASA Astrophysics Data System (ADS)

    Peng, H. L.; Voigtmann, Th.; Kolland, G.; Kobatake, H.; Brillo, J.

    2015-11-01

    We investigate temperature- and composition-dependent structural and dynamical properties of Al-Au melts. Experiments are performed to obtain accurate density and viscosity data. The system shows a strong negative excess volume, similar to other Al-based binary alloys. We develop a molecular-dynamics (MD) model of the melt based on the embedded-atom method (EAM), gauged against the available experimental liquid-state data. A rescaling of previous EAM potentials for solid-state Au and Al improves the quantitative agreement with experimental data in the melt. In the MD simulation, the admixture of Au to Al can be interpreted as causing a local compression of the less dense Al system, driven by less soft Au-Au interactions. This local compression provides a microscopic mechanism explaining the strong negative excess volume of the melt. We further discuss the concentration dependence of self- and interdiffusion and viscosity in the MD model. Al atoms are more mobile than Au, and their increased mobility is linked to a lower viscosity of the melt.

  9. Electric fields and chiral magnetic effect in Cu + Au collisions

    NASA Astrophysics Data System (ADS)

    Deng, Wei-Tian; Huang, Xu-Guang

    2015-03-01

    The non-central Cu + Au collisions can create strong out-of-plane magnetic fields and in-plane electric fields. By using the HIJING model, we study the general properties of the electromagnetic fields in Cu + Au collisions at 200 GeV and their impacts on the charge-dependent two-particle correlator γq1q2 = < cos ⁡ (ϕ1 +ϕ2 - 2ψRP) > (see main text for definition) which was used for the detection of the chiral magnetic effect (CME). Compared with Au + Au collisions, we find that the in-plane electric fields in Cu + Au collisions can strongly suppress the two-particle correlator or even reverse its sign if the lifetime of the electric fields is long. Combining with the expectation that if γq1q2 is induced by elliptic-flow driven effects we would not see such strong suppression or reversion, our results suggest to use Cu + Au collisions to test CME and understand the mechanisms that underlie γq1q2.

  10. Spin Polarization and Quantum Spins in Au Nanoparticles

    PubMed Central

    Li, Chi-Yen; Karna, Sunil K.; Wang, Chin-Wei; Li, Wen-Hsien

    2013-01-01

    The present study focuses on investigating the magnetic properties and the critical particle size for developing sizable spontaneous magnetic moment of bare Au nanoparticles. Seven sets of bare Au nanoparticle assemblies, with diameters from 3.5 to 17.5 nm, were fabricated with the gas condensation method. Line profiles of the X-ray diffraction peaks were used to determine the mean particle diameters and size distributions of the nanoparticle assemblies. The magnetization curves M(Ha) reveal Langevin field profiles. Magnetic hysteresis was clearly revealed in the low field regime even at 300 K. Contributions to the magnetization from different size particles in the nanoparticle assemblies were considered when analyzing the M(Ha) curves. The results show that the maximum particle moment will appear in 2.4 nm Au particles. A similar result of the maximum saturation magnetization appearing in 2.3 nm Au particles is also concluded through analysis of the dependency of the saturation magnetization MP on particle size. The MP(d) curve departs significantly from the 1/d dependence, but can be described by a log-normal function. Magnetization can be barely detected for Au particles larger than 27 nm. Magnetic field induced Zeeman magnetization from the quantum confined Kubo gap opening appears in Au nanoparticles smaller than 9.5 nm in diameter. PMID:23989607

  11. Synthesis of hybrid CdS-Au colloidal nanostructures.

    PubMed

    Saunders, Aaron E; Popov, Inna; Banin, Uri

    2006-12-21

    We explore the growth mechanism of gold nanocrystals onto preformed cadmium sulfide nanorods to form hybrid metal nanocrystal/semiconductor nanorod colloids. By manipulating the growth conditions, it is possible to obtain nanostructures exhibiting Au nanocrystal growth at only one nanorod tip, at both tips, or at multiple locations along the nanorod surface. Under anaerobic conditions, Au growth occurs only at one tip of the nanorods, producing asymmetric structures. In contrast, the presence of oxygen and trace amounts of water during the reaction promotes etching of the nanorod surface, providing additional sites for metal deposition. Three growth stages are observed when Au growth is performed under air: (1) Au nanocrystal formation at both nanorod tips, (2) growth onto defect sites on the nanorod surface, and finally (3) a ripening process in which one nanocrystal tip grows at the expense of the other particles present on the nanorod. Analysis of the hybrid nanostructures by high-resolution TEM shows that there is no preferred orientation between the Au nanocrystal and the CdS nanorod, indicating that growth is nonepitaxial. The optical signatures of the nanocrystals and the nanorods (i.e., the surface plasmon and first exciton transition peaks, respectively) are spectrally distinct, allowing the different stages of the growth process to be easily monitored. The initial CdS nanorods exhibit band gap and trap state emission, both of which are quenched during Au growth. PMID:17165989

  12. Surface segregation phenomena in extended and nanoparticle surfaces of Cu-Au alloys

    NASA Astrophysics Data System (ADS)

    Li, Jonathan; Wang, Guofeng; Zhou, Guangwen

    2016-07-01

    Using density functional theory (DFT) and Monte Carlo (MC) simulations, we studied the surface segregation phenomena of Au atoms in the extended and nanoparticle surfaces of Cu-Au alloys. Our MC simulations predicted significant Au enrichment in the outermost layer of (111) and (100) extended surfaces, and Au enrichment in the two outermost layers of (110) extended surfaces. The equilibrium Cu-Au nanoparticles were predicted to develop into an Au-enriched shell structure, where Au atoms preferably segregate to the (100) facets while Cu atoms are mainly located on the (111) facet of the nanoparticles. Our simulation predictions agree with experimental measurements.

  13. QUELS FUTURS TRAITEMENTS POUR LA DEPENDANCE AU TABAC ET AU CANNABIS?

    PubMed Central

    LE FOLL, Bernard; JUSTINOVA, Zuzana; TANDA, Gianlugi; GOLDBERG, Steven R.

    2009-01-01

    RESUME Plus de trois millions de morts sont attribués au tabagisme dans le monde par an, et l’usage de tabac est en progression dans les pays en voie de développement. L’usage de tabac est donc une des rares causes de mortalité qui augmente, avec une prévision de plus de 10 millions de morts par an dans 30–40 ans. Le cannabis ou marijuana est la drogue illicite la plus consommée dans le monde et il n’y a actuellement pas de traitement disponible. Bien que les systèmes dopaminergiques jouent un rôle central dans les effets renforçants des drogues, d’autres systèmes sont impliqués. Nous présentons ici des résultats récents obtenus avec des antagonistes des récepteurs cannabinoides CB1, des récepteurs D3 de la dopamine et des récepteurs opioïdes. Ces antagonistes qui modulent de façon directe ou indirecte la transmission dopaminergique cérébrale représentent des approches prometteuses pour le traitement du tabagisme ou de la dépendance au cannabis. Ces approches sont à valider dans des essais cliniques. PMID:18663981

  14. Beam Energy Dependence of the Third Harmonic of Azimuthal Correlations in Au +Au Collisions at RHIC

    NASA Astrophysics Data System (ADS)

    Adamczyk, L.; Adkins, J. K.; Agakishiev, G.; Aggarwal, M. M.; Ahammed, Z.; Alekseev, I.; Aparin, A.; Arkhipkin, D.; Aschenauer, E. C.; Attri, A.; Averichev, G. S.; Bai, X.; Bairathi, V.; Bellwied, R.; Bhasin, A.; Bhati, A. K.; Bhattarai, P.; Bielcik, J.; Bielcikova, J.; Bland, L. C.; Bordyuzhin, I. G.; Bouchet, J.; Brandenburg, J. D.; Brandin, A. V.; Bunzarov, I.; Butterworth, J.; Caines, H.; Calderón de la Barca Sánchez, M.; Campbell, J. M.; Cebra, D.; Chakaberia, I.; Chaloupka, P.; Chang, Z.; Chatterjee, A.; Chattopadhyay, S.; Chen, J. H.; Chen, X.; 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. I.; Hamed, A.; Haque, R.; Harris, J. W.; He, L.; Heppelmann, S.; Heppelmann, S.; Hirsch, A.; Hoffmann, G. W.; Horvat, S.; Huang, T.; Huang, X.; Huang, B.; Huang, H. Z.; Huck, P.; Humanic, T. J.; Igo, G.; Jacobs, W. W.; Jang, H.; Jentsch, A.; 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.; Kisel, I.; 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, C.; Li, X.; Li, Y.; Li, W.; Lin, T.; Lisa, M. A.; Liu, F.; Ljubicic, T.; Llope, W. J.; Lomnitz, M.; Longacre, R. S.; Luo, X.; Ma, R.; Ma, G. L.; Ma, Y. G.; Ma, L.; Magdy, N.; Majka, R.; Manion, A.; Margetis, S.; Markert, C.; Matis, H. S.; McDonald, D.; McKinzie, S.; 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. A.; Olvitt, D.; Page, B. S.; Pak, R.; Pan, Y. X.; Pandit, Y.; Panebratsev, Y.; Pawlik, B.; Pei, H.; Perkins, C.; 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, S.; Raniwala, R.; Ray, R. L.; Ritter, H. G.; Roberts, J. B.; Rogachevskiy, O. V.; Romero, J. L.; 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, A.; Sharma, B.; Sharma, M. K.; Shen, W. Q.; Shi, Z.; Shi, S. S.; Shou, Q. Y.; Sichtermann, E. P.; Sikora, R.; Simko, M.; Singha, S.; Skoby, M. J.; Smirnov, N.; Smirnov, D.; Solyst, W.; Song, L.; Sorensen, P.; Spinka, H. M.; Srivastava, B.; Stanislaus, T. D. S.; Stepanov, M.; Stock, R.; Strikhanov, M.; Stringfellow, B.; Sumbera, M.; Summa, B.; Sun, Z.; Sun, X. M.; Sun, Y.; Surrow, B.; Svirida, D. N.; Tang, Z.; Tang, A. H.; Tarnowsky, T.; Tawfik, A.; Thäder, J.; 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.; Vokal, S.; Voloshin, S. A.; Vossen, A.; Wang, F.; Wang, G.; Wang, J. S.; Wang, H.; Wang, Y.; Wang, Y.; Webb, G.; Webb, J. C.; Wen, L.; Westfall, G. D.; Wieman, H.; Wissink, S. W.; Witt, R.; Wu, Y.; Xiao, Z. G.; Xie, W.; Xie, G.; Xin, K.; Xu, Y. F.; Xu, Q. H.; Xu, N.; Xu, H.; Xu, Z.; Xu, J.; Yang, S.; Yang, Y.; Yang, Y.; Yang, C.; Yang, Y.; Yang, Q.; Ye, Z.; Ye, Z.; Yepes, P.; Yi, L.; Yip, K.; Yoo, I.-K.; Yu, N.; Zbroszczyk, H.; Zha, W.; Zhang, X. P.; Zhang, Y.; Zhang, J.; Zhang, J.; Zhang, S.; Zhang, S.; Zhang, Z.; Zhang, J. B.; Zhao, J.; Zhong, C.; Zhou, L.; Zhu, X.; Zoulkarneeva, Y.; Zyzak, M.; STAR Collaboration

    2016-03-01

    We present results from a harmonic decomposition of two-particle azimuthal correlations measured with the STAR detector in Au +Au collisions for energies ranging from √{sN N }=7.7 to 200 GeV. The third harmonic v32{2 }=⟨cos 3 (ϕ1-ϕ2)⟩ , where ϕ1-ϕ2 is the angular difference in azimuth, is studied as a function of the pseudorapidity difference between particle pairs Δ η =η1-η2 . Nonzero v32{2 } is directly related to the previously observed large-Δ η narrow-Δ ϕ ridge correlations and has been shown in models to be sensitive to the existence of a low viscosity quark gluon plasma phase. For sufficiently central collisions, v32{2 } persist down to an energy of 7.7 GeV, suggesting that quark gluon plasma may be created even in these low energy collisions. In peripheral collisions at these low energies, however, v32{2 } is consistent with zero. When scaled by the pseudorapidity density of charged-particle multiplicity per participating nucleon pair, v32{2 } for central collisions shows a minimum near √{sN N }=20 GeV .

  15. Azimuthal anisotophy in U + U and Au + Au collisions at RHIC

    SciTech Connect

    Adamczyk, L.

    2015-11-24

    Collisions between prolate uranium nuclei are used to study how particle production and azimuthal anisotropies depend on initial geometry in heavy-ion collisions. We report the two- and four-particle cumulants, v2{2} and v2{4}, for charged hadrons from U+U collisions at √SNN = 193 GeV and Au+Au collisions at √SNN = 200 GeV. Nearly fully overlapping collisions are selected based on the energy deposited by spectators in zero degree calorimeters (ZDCs). Within this sample, the observed dependence of v2{2} on multiplicity demonstrates that ZDC information combined with multiplicity can preferentially select different overlap configurations in U+U collisions. As a result, we also show that v2 vs multiplicity can be better described by models, such as gluon saturation or quark participant models, that eliminate the dependence of the multiplicity on the number of binary nucleon-nucleon collisions.

  16. Azimuthal anisotophy in U + U and Au + Au collisions at RHIC

    DOE PAGESBeta

    Adamczyk, L.

    2015-11-24

    Collisions between prolate uranium nuclei are used to study how particle production and azimuthal anisotropies depend on initial geometry in heavy-ion collisions. We report the two- and four-particle cumulants, v2{2} and v2{4}, for charged hadrons from U+U collisions at √SNN = 193 GeV and Au+Au collisions at √SNN = 200 GeV. Nearly fully overlapping collisions are selected based on the energy deposited by spectators in zero degree calorimeters (ZDCs). Within this sample, the observed dependence of v2{2} on multiplicity demonstrates that ZDC information combined with multiplicity can preferentially select different overlap configurations in U+U collisions. As a result, we alsomore » show that v2 vs multiplicity can be better described by models, such as gluon saturation or quark participant models, that eliminate the dependence of the multiplicity on the number of binary nucleon-nucleon collisions.« less

  17. Dielectron Mass Spectra from Au +Au Collisions at √sNN =200 GeV

    NASA Astrophysics Data System (ADS)

    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.; Barnovska, Z.; 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.; 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.; 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.; Grosnick, D.; Guo, Y.; Gupta, A.; Gupta, S.; Guryn, W.; Haag, B.; Hajkova, O.; 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.; Korsch, W.; Kotchenda, L.; 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.; Lima, L. M.; Lisa, M. A.; Liu, F.; Ljubicic, T.; Llope, W. J.; 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.; Munhoz, M. G.; Mustafa, M. K.; Nandi, B. K.; Nasim, Md.; Nayak, T. K.; Nelson, J. M.; Nogach, L. V.; Noh, S. Y.; Novak, J.; Nurushev, S. B.; Odyniec, G.; Ogawa, A.; Oh, K.; Ohlson, A.; Okorokov, V.; Oldag, E. W.; Oliveira, R. A. N.; 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.; Plyku, D.; Poljak, N.; Porter, J.; Poskanzer, A. M.; Pruthi, N. K.; Przybycien, M.; Pujahari, P. R.; 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.; Sahoo, N. R.; Sahu, P. K.; Sakrejda, I.; Salur, S.; Sandacz, A.; 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.; deSouza, U. G.; Spinka, H. M.; Srivastava, B.; Stanislaus, T. D. S.; Stevens, J. R.; Stock, R.; Strikhanov, M.; Stringfellow, B.; Suaide, A. A. P.; Sumbera, M.; Sun, X.; Sun, X. M.; Sun, Y.; Sun, Z.; Surrow, B.; Svirida, D. N.; Symons, T. J. M.; Szanto de Toledo, 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.; 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, 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.; 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

    2014-07-01

    We report the STAR measurements of dielectron (e+e-) production at midrapidity (|yee|<1) in Au +Au collisions at √sNN =200 GeV. The measurements are evaluated in different invariant mass regions with a focus on 0.30-0.76 (ρ-like), 0.76-0.80 (ω-like), and 0.98-1.05 (ϕ-like) GeV /c2. The spectrum in the ω-like and ϕ-like regions can be well described by the hadronic cocktail simulation. In the ρ-like region, however, the vacuum ρ spectral function cannot describe the shape of the dielectron excess. In this range, an enhancement of 1.77±0.11(stat)±0.24(syst)±0.33(cocktail) is determined with respect to the hadronic cocktail simulation that excludes the ρ meson. The excess yield in the ρ-like region increases with the number of collision participants faster than the ω and ϕ yields. Theoretical models with broadened ρ contributions through interactions with constituents in the hot QCD medium provide a consistent description of the dilepton mass spectra for the measurement presented here and the earlier data at the Super Proton Synchrotron energies.

  18. RHIC PERFORMANCE DURING THE FY10 200 GeV Au+Au HEAVY ION RUN

    SciTech Connect

    Brown, K.A.; Ahrens, L.; Bai, M.; Beebe-Wang, J.; Blaskiewicz, M.; Brennan, J.; Bruno, D.; Carlson, C.; Connolly, R.; de Maria, R.; D’Ottavio, T.; Drees, A.; Fischer, W.; Fu, W.; Gardner, C.; Gassner, D.; Glenn, J.W.; Hao, Y.; Harvey, M.; Hayes, T.; Hoff, L.; Huang, H.; Laster, J.; Lee, R.; Litvinenko, V.; Luo, Y.; MacKay, W.; Marr, G.; Marusic, A.; Mernick, K.; Michnoff, R.; Minty, M.; Montag, C.; Morris, J.; Nemesure, S.; Oerter, B.; Pilat, F.; Ptitsyn, V.; Robert-Demolaize, G.; Roser, T.; Russo, T.; Sampson, P.; Sandberg, J.; Satogata, T.; Severino, F.; Schoefer, V.; Schultheiss, C.; Smith, K.; Steski, D.; Tepikian, S.; Theisen, C.; Thieberger, P.; Trbojevic, D.; Tsoupas, N.; Tuozzolo, J.; Wang, G.; Wilinski, M.; Zaltsman, A.; Zeno, K.; Zhang, S.Y.

    2010-05-23

    Since the last successful RHIC Au+Au run in 2007 (Run-7), the RHIC experiments have made numerous detector improvements and upgrades. In order to benefit from the enhanced detector capabilities and to increase the yield of rare events in the acquired heavy ion data a significant increase in luminosity is essential. In Run-7 RHIC achieved an average store luminosity of = 12 x 10{sup 26} cm{sup -2} s{sup -1} by operating with 103 bunches (out of 111 possible), and by squeezing to {beta}* = 0.85 m. This year, Run-10, we achieved = 20 x 10{sup 26} cm{sup -2} s{sup -1}, which put us an order of magnitude above the RHIC design luminosity. To reach these luminosity levels we decreased {beta}* to 0.75 m, operated with 111 bunches per ring, and reduced longitudinal and transverse emittances by means of bunched-beam stochastic cooling. In addition we introduced a lattice to suppress intra-beam scattering (IBS) in both RHIC rings, upgraded the RF control system, and separated transition crossing times in the two rings. We present an overview of the changes and the results of Run-10 performance.

  19. A first look at Au+Au collisions at RHIC energies using the PHOBOS detector.

    SciTech Connect

    Back, B. B.; George, N.; Wousmaa, A. H.; Baker, M. D.; Barton, D. S.; PHOBOS Collaboration; Physics

    2003-05-01

    The PHOBOS detector has been used to study Au + Au collisions at {radical}sNN = 56,130, and 200 GeV Several global observables have been measured and the results are compared with theoretical models. These observables include the charged-particle multiplicity measured as a function of beam energy, pseudo-rapidity, and centrality of the collision. A unique feature of the PHOBOS detector is its almost complete angular coverage such that these quantities can be studied over a pseudo-rapidity interval of |{eta}|{<=}5.4. This allows for an almost complete integration of the total charged particle yield, which is found to be about N{sub ch}{sup tot} = 4200 {+-}470 at {radical}sNN = 130 GeV and N{sub ch}{sup tot} = 5300 {+-}530 at {radical}sNN = 200 GeV. The ratio of anti-particles to particles emitted in the mid-rapidity region has also been measured using the PHOBOS magnetic spectrometer. Of particular interest is the ratio of anti-protons to protons in the mid-rapidity region, which was found to be (i.e.921-1) at {radical}sNN = 130 GeV. This high value suggests that an almost baryon-free region has been produced in the collisions.

  20. Rapidity dependency of (Anti)-deuteron Coalescence in Au-Au collisions

    NASA Astrophysics Data System (ADS)

    Murray, Michael

    2009-05-01

    The coalescence of protons and neutrons into deuterons is sensitive to the space-time extent of the baryon freeze-out region. The coalescence parameter and the phase space density recast the information contained in the proton and deuteron spectra into ``chemical" and ``dynamic" terms. The phase space density is sensitive to the chemical potential and the temperature of the system. The coalescence parameter B2 can be interpreted in terms of a ``volume of homogeniety" which depends upon the temperature of the system and the radial flow. The large rapidity and pT coverage with good particle identification of the BRAHMS spectrometers allow us to measure the rapidity dependence of the volume, which is proportional to 1/B2, and the phase space density of the (anti)-proton source for central Au+Au collisions. We find that B2(pT) is almost independent of rapidity and beam energy. Interpreting 1/B2 as a volume gives numbers that are very close to HBT data and a size which steadily drops with pT. We find that B2(pT) is the same for protons and antiprotons. The phase space density has a weak rapidity dependence but varies rapidily with energy. These results in conjunction with other forward rapidity data start to give us a picture of the longitudinal evolution of the source at RHIC energies. Supported by NSF CAREER award 0449913

  1. Scaling properties of proton and antiproton production in sqrt[s(NN)]=200 GeV Au+Au collisions.

    PubMed

    Adler, S S; Afanasiev, S; Aidala, C; Ajitanand, N N; Akiba, Y; Alexander, J; Amirikas, R; Aphecetche, L; Aronson, S H; Averbeck, R; Awes, T C; Azmoun, R; Babintsev, V; Baldisseri, A; Barish, K N; Barnes, P D; Bassalleck, B; Bathe, S; Batsouli, S; Baublis, V; Bazilevsky, A; Belikov, S; Berdnikov, Y; Bhagavatula, S; Boissevain, J G; Borel, H; Borenstein, S; Brooks, M L; Brown, D S; Bruner, N; Bucher, D; Buesching, H; Bumazhnov, V; Bunce, G; Burward-Hoy, J M; Butsyk, S; Camard, X; Chai, J-S; Chand, P; Chang, W C; Chernichenko, S; Chi, C Y; Chiba, J; Chiu, M; Choi, I J; Choi, J; Choudhury, R K; Chujo, T; Cianciolo, V; Cobigo, Y; Cole, B A; Constantin, P; d'Enterria, D G; David, G; Delagrange, H; Denisov, A; Deshpande, A; Desmond, E J; Dietzsch, O; Drapier, O; Drees, A; du Rietz, R; Durum, A; Dutta, D; Efremenko, Y V; El Chenawi, K; Enokizono, A; En'yo, H; Esumi, S; Ewell, L; Fields, D E; Fleuret, F; Fokin, S L; Fox, B D; Fraenkel, Z; Frantz, J E; Franz, A; Frawley, A D; Fung, S-Y; Garpman, S; Ghosh, T K; Glenn, A; Gogiberidze, G; Gonin, M; Gosset, J; Goto, Y; Granier de Cassagnac, R; Grau, N; Greene, S V; Grosse Perdekamp, G; Guryn, W; Gustafsson, H-A; Hachiya, T; Haggerty, J S; Hamagaki, H; Hansen, A G; Hartouni, E P; Harvey, M; Hayano, R; He, X; Heffner, M; Hemmick, T K; Heuser, J M; Hibino, M; Hill, J C; Holzmann, W; Homma, K; Hong, B; Hoover, A; Ichihara, T; Ikonnikov, V V; Imai, K; Isenhower, L D; Ishihara, M; Issah, M; Isupov, A; Jacak, B V; Jang, W Y; Jeong, Y; Jia, J; Jinnouchi, O; Johnson, B M; Johnson, S C; Joo, K S; Jouan, D; Kametani, S; Kamihara, N; Kang, J H; Kapoor, S S; Katou, K; Kelly, S; Khachaturov, B; Khanzadeev, A; Kikuchi, J; Kim, D H; Kim, D J; Kim, D W; Kim, E; Kim, G-B; Kim, H J; Kistenev, E; Kiyomichi, A; Kiyoyama, K; Klein-Boesing, C; Kobayashi, H; Kochenda, L; Kochetkov, V; Koehler, D; Kohama, T; Kopytine, M; Kotchetkov, D; Kozlov, A; Kroon, P J; Kuberg, C H; Kurita, K; Kuroki, Y; Kweon, M J; Kwon, Y; Kyle, G S; Lacey, R; Ladygin, V; Lajoie, J G; Lebedev, A; Leckey, S; Lee, D M; Lee, S; Leitch, M J; Li, X H; Lim, H; Litvinenko, A; Liu, M X; Liu, Y; Maguire, C F; Makdisi, Y I; Malakhov, A; Manko, V I; Mao, Y; Martinez, G; Marx, M D; Masui, H; Matathias, F; Matsumoto, T; McGaughey, P L; Melnikov, E; Messer, F; Miake, Y; Milan, J; Miller, T E; Milov, A; Mioduszewski, S; Mischke, R E; Mishra, G C; Mitchell, J T; Mohanty, A K; Morrison, D P; Moss, J M; Mühlbacher, F; Mukhopadhyay, D; Muniruzzaman, M; Murata, J; Nagamiya, S; Nagle, J L; Nakamura, T; Nandi, B K; Nara, M; Newby, J; Nilsson, P; Nyanin, A S; Nystrand, J; O'Brien, E; Ogilvie, C A; Ohnishi, H; Ojha, I D; Okada, K; Ono, M; Onuchin, V; Oskarsson, A; Otterlund, I; Oyama, K; Ozawa, K; Pal, D; Palounek, A P T; Pantuev, V S; Papavassiliou, V; Park, J; Parmar, A; Pate, S F; Peitzmann, T; Peng, J-C; Peresedov, V; Pinkenburg, C; Pisani, R P; Plasil, F; Purschke, M L; Purwar, A; Rak, J; Ravinovich, I; Read, K F; Reuter, M; Reygers, K; Riabov, V; Riabov, Y; Roche, G; Romana, A; Rosati, M; Rosnet, P; Ryu, S S; Sadler, M E; Saito, N; Sakaguchi, T; Sakai, M; Sakai, S; Samsonov, V; Sanfratello, L; Santo, R; Sato, H D; Sato, S; Sawada, S; Schutz, Y; Semenov, V; Seto, R; Shaw, M R; Shea, T K; Shibata, T-A; Shigaki, K; Shiina, T; Silva, C L; Silvermyr, D; Sim, K S; Singh, C P; Singh, V; Sivertz, M; Soldatov, A; Soltz, R A; Sondheim, W E; Sorensen, S P; Sourikova, I V; Staley, F; Stankus, P W; Stenlund, E; Stepanov, M; Ster, A; Stoll, S P; Sugitate, T; Sullivan, J P; Takagui, E M; Taketani, A; Tamai, M; Tanaka, K H; Tanaka, Y; Tanida, K; Tannenbaum, M J; Tarján, P; Tepe, J D; Thomas, T L; Tojo, J; Torii, H; Towell, R S; Tserruya, I; Tsuruoka, H; Tuli, S K; Tydesjö, H; Tyurin, N; Van Hecke, H W; Velkovska, J; Velkovsky, M; Villatte, L; Vinogradov, A A; Volkov, M A; Vznuzdaev, E; Wang, X R; Watanabe, Y; White, S N; Wohn, F K; Woody, C L; Xie, W; Yang, Y; Yanovich, A; Yokkaichi, S; Young, G R; Yushmanov, I E; Zajc, W A; Zhang, C; Zhou, S; Zolin, L

    2003-10-24

    We report on the yield of protons and antiprotons, as a function of centrality and transverse momentum, in Au+Au collisions at sqrt[s(NN)]=200 GeV measured at midrapidity by the PHENIX experiment at the BNL Relativistic Heavy Ion Collider. In central collisions at intermediate transverse momenta (1.5Au+Au, p+p, and e(+)e(-) collisions. This enhancement is limited to p(T)<5 GeV/c as deduced from the ratio of charged hadrons to pi(0) measured in the range 1.5

  2. Transition from participant to spectator fragmentation in Au+Au reactions between 60A and 150A MeV

    SciTech Connect

    Zbiri, K.; Aichelin, J.; Le Fevre, A.; Lukasik, J.; Reisdorf, W.; Lynen, U.; Mueller, W. F. J.; Orth, H.; Schwarz, C.; Sfienti, C.; Trautmann, W.; Turzo, K.; Gulminelli, F.; Lopez, O.; Vient, E.; Zwieglinski, B.; Chbihi, A.; Frankland, J. D.; Wieleczko, J. P.; Charvet, J. L.

    2007-03-15

    Using the quantum molecular dynamics approach, we analyzed the results of the recent INDRA Collaboration Au+Au experiments at GSI in the energy range between 60A and 150A MeV. It turns out that in this energy region, the transition toward a participant-spectator scenario takes place. The large Au+Au system displays, in the simulations as in the experiment, simultaneously dynamical and statistical behavior, which we analyze in detail. The composition of fragments close to midrapidity follows statistical laws, and the system shows bimodality, i.e., a sudden transition between different fragmentation patterns, as a function of centrality, as expected for a phase transition. The fragment spectra at small and large rapidities, on the other hand, are determined by dynamics, and the system as a whole does not come to equilibrium--an observation that is confirmed by FOPI Collaboration experiments for the same system.

  3. Centrality and collision system dependence of antiproton production from p+A to Au+Au collisions at AGS energies

    NASA Technical Reports Server (NTRS)

    Sako, H.; Ahle, L.; Akiba, Y.; Ashktorab, K.; Baker, M. D.; Beavis, D.; Britt, H. C.; Chang, J.; Chasman, C.; Chen, Z.; Chu, Y. Y.; Cianciolo, V.; Cole, B. A.; Crawford, H. J.; Cumming, J. B.; Debbe, R.; Dunlop, J. C.; Eldredge, W.; Engelage, J.; Fung, S.-Y.

    1997-01-01

    Antiproton production in heavy ion collisions reflects subtle interplay between initial production and absorption by nucleons. Because the AGS energies (10--20 A(center-dot)GeV/c) are close to the antiproton production threshold, antiproton may be sensitive to cooperative processes such as QGP and hadronic multi-step processes. On the other hand, antiproton has been proposed as a probe of baryon density due to large N(anti N) annihilation cross sections. Cascade models predict the maximum baryon density reaches about 10 times the normal nucleus density in central Au+Au collisions, where the strong antiproton absorption is expected. In this paper, the authors show systematic studies of antiproton production from p+A to Au+Au collisions.

  4. Strangeness enhancement in Cu-Cu and Au-Au collisions at √S(NN)=200 GeV.

    PubMed

    Agakishiev, G; Aggarwal, M M; Ahammed, Z; Alakhverdyants, A V; Alekseev, I; Alford, J; Anderson, B D; Anson, C D; Arkhipkin, D; Averichev, G S; Balewski, J; Barnby, L S; Beavis, D R; Behera, N K; Bellwied, R; Betancourt, M J; Betts, R R; Bhasin, A; Bhati, A K; Bichsel, H; Bielcik, J; Bielcikova, J; Bland, L C; Bordyuzhin, I G; Borowski, W; Bouchet, J; Braidot, E; Brandin, A V; Bridgeman, A; Brovko, S G; Bruna, E; Bueltmann, S; Bunzarov, I; Burton, T P; Cai, X Z; Caines, H; Sánchez, M Calderón de la Barca; Cebra, D; Cendejas, R; Cervantes, M C; Chaloupka, P; Chattopadhyay, S; Chen, H F; Chen, J H; Chen, J Y; Chen, L; Cheng, J; Cherney, M; Chikanian, A; Choi, K E; Christie, W; Chung, P; Codrington, M J M; Corliss, R; Cramer, J G; Crawford, H J; Cui, X; Leyva, A Davila; De Silva, L C; Debbe, R R; Dedovich, T G; Deng, J; Derevschikov, A A; de Souza, R Derradi; Didenko, L; Djawotho, P; Dogra, S M; Dong, X; Drachenberg, J L; Draper, J E; Du, C M; Dunlop, J C; Efimov, L G; Elnimr, M; Engelage, J; Eppley, G; Estienne, M; Eun, L; Evdokimov, O; Fatemi, R; Fedorisin, J; Fersch, R G; Filip, P; Finch, E; Fine, V; Fisyak, Y; Gagliardi, C A; Gangadharan, D R; Geurts, F; Ghosh, P; Gorbunov, Y N; Gordon, A; Grebenyuk, O G; Grosnick, D; Gupta, A; Gupta, S; Guryn, W; Haag, B; Hajkova, O; Hamed, A; Han, L-X; Harris, J W; Hays-Wehle, J P; Heinz, M; Heppelmann, S; Hirsch, A; Hjort, E; Hoffmann, G W; Hofman, D J; Huang, B; Huang, H Z; Humanic, T J; Huo, L; Igo, G; Jacobs, P; Jacobs, W W; Jena, C; Jin, F; Jones, P G; Joseph, J; Judd, E G; Kabana, S; Kang, K; Kapitan, J; Kauder, K; Ke, H W; Keane, D; Kechechyan, A; Kettler, D; Kikola, D P; Kiryluk, J; Kisiel, A; Kizka, V; Klein, S R; Knospe, A G; Koetke, D D; Kollegger, T; Konzer, J; Koralt, I; Koroleva, L; Korsch, W; Kotchenda, L; Kouchpil, V; Kravtsov, P; Krueger, K; Krus, M; Kumar, L; Lamont, M A C; Landgraf, J M; LaPointe, S; Lauret, J; Lebedev, A; Lednicky, R; Lee, J H; Leight, W; LeVine, M J; Li, C; Li, L; Li, N; Li, W; Li, X; Li, X; Li, Y; Li, Z M; Lima, L M; Lisa, M A; Liu, F; Liu, H; Liu, J; Ljubicic, T; Llope, W J; Longacre, R S; Lu, Y; Lukashov, E V; Luo, X; Ma, G L; Ma, Y G; Mahapatra, D P; Majka, R; Mall, O I; Manweiler, R; Margetis, S; Markert, C; Masui, H; Matis, H S; McDonald, D; McShane, T S; Meschanin, A; Milner, R; Minaev, N G; Mioduszewski, S; Mitrovski, M K; Mohammed, Y; Mohanty, B; Mondal, M M; Morozov, B; Morozov, D A; Munhoz, M G; Mustafa, M K; Naglis, M; Nandi, B K; Nayak, T K; Nelson, J M; Nogach, L V; Nurushev, S B; Odyniec, G; Ogawa, A; Oh, K; Ohlson, A; Okorokov, V; Oldag, E W; Oliveira, R A N; Olson, D; Pachr, M; Page, B S; Pal, S K; Pandit, Y; Panebratsev, Y; Pawlak, T; Pei, H; Peitzmann, T; Perkins, C; Peryt, W; Pile, P; Planinic, M; Ploskon, M A; Pluta, J; Plyku, D; Poljak, N; Porter, J; Poskanzer, A M; Potukuchi, B V K S; Powell, C B; Prindle, D; Pruneau, C; Pruthi, N K; Pujahari, P R; Putschke, J; Qiu, H; Raniwala, R; Raniwala, S; Ray, R L; Redwine, R; Reed, R; Ritter, H G; Roberts, J B; Rogachevskiy, O V; Romero, J L; Ruan, L; Rusnak, J; Sahoo, N R; Sakrejda, I; Salur, S; Sandweiss, J; Sangaline, E; Sarkar, A; Schambach, J; Scharenberg, R P; Schaub, J; Schmah, A M; Schmitz, N; Schuster, T R; Seele, J; Seger, J; Selyuzhenkov, I; Seyboth, P; Shah, N; Shahaliev, E; Shao, M; Sharma, M; Shi, S S; Shou, Q Y; Sichtermann, E P; Simon, F; Singaraju, R N; Skoby, M J; Smirnov, N; Solanki, D; Sorensen, P; deSouza, U G; Spinka, H M; Srivastava, B; Stanislaus, T D S; Steadman, S G; Stevens, J R; Stock, R; Strikhanov, M; Stringfellow, B; Suaide, A A P; Suarez, M C; Subba, N L; Sumbera, M; Sun, X M; Sun, Y; Sun, Z; Surrow, B; Svirida, D N; Symons, T J M; de Toledo, A Szanto; Takahashi, J; Tang, A H; Tang, Z; Tarini, L H; Tarnowsky, T; Thein, D; Thomas, J H; Tian, J; Timmins, A R; Tlusty, D; Tokarev, M; Trainor, T A; Trentalange, S; Tribble, R E; Tribedy, P; Trzeciak, B A; Tsai, O D; Ullrich, T; Underwood, D G; Van Buren, G; van Nieuwenhuizen, G; Vanfossen, J A; Varma, R; Vasconcelos, G M S; Vasiliev, A N; Videbæk, 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; Webb, J C; Westfall, G D; Whitten, C; Wieman, H; Wissink, S W; Witt, R; Witzke, W; Wu, Y F; Xiao, Z; Xie, W; Xu, H; Xu, N; Xu, Q H; Xu, W; Xu, Y; Xu, Z; Xue, L; Yang, Y; Yang, Y; Yepes, P; Yip, K; Yoo, I-K; Zawisza, M; Zbroszczyk, H; Zhan, W; Zhang, J B; Zhang, S; Zhang, W M; Zhang, X P; Zhang, Y; Zhang, Z P; Zhao, F; Zhao, J; Zhong, C; Zhu, X; Zhu, Y H; Zoulkarneeva, Y

    2012-02-17

    We report new STAR measurements of midrapidity yields for the Λ, Λ[over ¯], K(S)(0), Ξ(-), Ξ[over ¯](+), Ω(-), Ω[over ¯](+) particles in Cu+Cu collisions at √S(NN)==200  GeV, and midrapidity yields for the Λ, Λ[over ¯], K(S)(0) particles in Au+Au at √S(NN)==200  GeV. We show that, at a given number of participating nucleons, the production of strange hadrons is higher in Cu+Cu collisions than in Au+Au collisions at the same center-of-mass energy. We find that aspects of the enhancement factors for all particles can be described by a parametrization based on the fraction of participants that undergo multiple collisions. PMID:22401196

  5. MMENT>Computational study of complete methanol dehydrogenation on Au(100) and Au(310) surfaces: Dominant role of atomic oxygen

    NASA Astrophysics Data System (ADS)

    Hussain, A.; Shah, S. H.

    2014-02-01

    Methanol dehydrogenation to CO and H2 has been systematically investigated on Au(100) and Au(310) surfaces using density functional theory (DFT). All possible intermediates involved are calculated. Methanol and formaldehyde being saturated molecules adsorb weakly on both the surfaces. The thermochemistry and kinetics of the decomposition via sequential hydrogen abstraction are both found to be highly unfavorable for these species. Nevertheless, atomic oxygen pre-covered surfaces substantially enhance CH3OH and CH2O (resulting in CH2O2 complex formation) interaction with Au and offer weak activation barrier for methanol disintegration into CH3O and H. On the other hand, methoxy, formyl, and atomic hydrogen are predicted to make strong chemical bonds with the clean Au surfaces. The abstraction of hydrogen from the methoxy intermediate on bare gold surfaces is practical, while formyl splits instantaneously during optimization. A feasible mechanism on oxygen pre-covered surfaces for complete methanol dehydrogenation has been presented.

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

    NASA Astrophysics Data System (ADS)

    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

  7. Azimuthally sensitive hanbury brown-twiss interferometry in Au + Au collisions sqrt S sub NN = 200 GeV

    SciTech Connect

    Adams, J.; Adler, C.; Aggarwal, M.M.; Ahammed, Z.; Amonett, J.; Anderson, B.D.; Arkhipkin, D.; Averichev, G.S.; Badyal, S.K.; Balewski, J.; Barannikova, O.; Barnby, L.S.; Baudot, J.; Bekele, S.; Belaga, V.V.; Bellwied, R.; Berger, J.; Bezverkhny, B.I.; Bhardwaj, S.; Bhati, A.K.; Bichsel, H.; Billmeier, A.; Bland, L.C.; Blyth, C.O.; Bonner, B.E.; Botje, M.; Boucham, A.; Brandin, A.; Bravar, A.; Cadman, R.V.; Cai, X.Z.; Caines, H.; Calderon de la Barca Sanchez, M.; Carroll, J.; Castillo, J.; Cebra, D.; Chaloupka, P.; Chattopadhyay, S.; Chen, H.F.; Chen, Y.; Chernenko, S.P.; Cherney, M.; Chikanian, A.; Christie, W.; Coffin, J.P.; Cormier, T.M.; Cramer, J.G.; Crawford, H.J.; Das, D.; Das, S.; Derevschikov, A.A.; Didenko, L.; Dietel, T.; Dong, W.J.; Dong, X.; Draper, J.E.; Du, F.; Dubey, A.K.; Dunin, V.B.; Dunlop, J.C.; Dutta Majumdar, M.R.; Eckardt, V.; Efimov, L.G.; Emelianov, V.; Engelage, J.; Eppley, G.; Erazmus, B.; Estienne, M.; Fachini, P.; Faine, V.; Faivre, J.; Fatemi, R.; Filimonov, K.; Filip, P.; Finch, E.; Fisyak, Y.; Flierl, D.; Foley, K.J.; Fu, J.; Gagliardi, C.A.; Gagunashvili, N.; Gans, J.; Gaudichet, L.; Geurts, F.; Ghazikhanian, V.; Ghosh, P.; Gonzalez, J.E.; Grachov, O.; Grebenyuk, O.; Gronstal, S.; Grosnick, D.; Guertin, S.M.; Gupta, A.; Gutierrez, T.D.; Hallman, T.J.; Hamed, A.; Hardtke, D.; Harris, J.W.; Heinz, M.; Henry, T.W.; Heppelmann, S.; Hippolyte, B.; Hirsch, A.; Hjort, E.; Hoffmann, G.W.; Horsley, M.; Huang, H.Z.; Huang, L.S.; Hughes, E.; Humanic, T.J.; Igo, G.; Ishihara, A.; Jacobs, P.; Jacobs, W.W.; Janik, M.; Jiang, H.; Johnson, I.; Jones, P.G.; Judd, E.G.; Kabana, S.; Kaplan, M.; Keane, D.; Khodyrev, V.Yu.; Kiryluk, J.; Kisiel, A.; Klay, J.; Klein, S.R.; Klyachko, A.; Koetke, D.D.; Kollegger, T.; Kopytine, M.; Kotchenda, L.; Kovalenko, A.D.; Kramer, M.; Kravtsov, V.I.; Kravtsov, P.; Krueger, K.; Kuhn, C.; Kulikov, A.I.; Kumar, A.; Kunde, G.J.; Kunz, C.L.; Kutuev, R.Kh.; Kuznetsov, A.A.; Lamont, M.A.C.; et al.

    2004-06-30

    We present the results of a systematic study of the shape of the pion distribution in coordinate space at freeze-out in Au+Au collisions at RHIC using two-pion Hanbury Brown-Twiss (HBT) interferometry. Oscillations of the extracted HBT radii vs. emission angle indicate sources elongated perpendicular to the reaction plane. The results indicate that the pressure and expansion time of the collision system are not sufficient to completely quench its initial shape.

  8. NUCLEAR AND HEAVY ION PHYSICS: Charged-particle pseudorapidity distributions in Au+Au collisions at RHIC

    NASA Astrophysics Data System (ADS)

    Wang, Zeng-Wei; Jiang, Zhi-Jin

    2009-04-01

    Using the Glauber model, we present the formulas for calculating the numbers of participants, spectators and binary nucleon-nucleon collisions. Based on this work, we get the pseudorapidity distributions of charged particles as the function of the impact parameter in nucleus-nucleus collisions. The theoretical results agree well with the experimental observations made by the BRAHMS Collaboration in Au + Au collisions at GeV in different centrality bins over the whole pseudorapidity range.

  9. Rationalization of Au concentration and distribution in AuNi@Pt core-shell nanoparticles for oxygen reduction reaction

    SciTech Connect

    An, Wei; Liu, Ping

    2015-09-18

    Improving the activity and stability of Pt-based core–shell nanocatalysts for proton exchange membrane fuel cells while lowering Pt loading has been one of the big challenges in electrocatalysis. Here, using density functional theory, we report the effect of adding Au as the third element to enhance the durability and activity of Ni@Pt core–shell nanoparticles (NPs) during the oxygen reduction reaction (ORR). Our results show that the durability and activity of a Ni@Pt NP can be finely tuned by controlling Au concentration and distribution. For a NiAu@Pt NP, the durability can be greatly promoted by thermodynamically favorable segregation of Au to replace the Pt atoms at vertex, edge, and (100) facets on the shell, while still keeping the ORR activity on the active Pt(111) shell as high as that of Ni@Pt nanoparticles. Such behavior strongly depends on a direct interaction with the Ni interlayer. The results not only highlight the importance of interplay between surface strain on the shell and the interlayer–shell interaction in determining the durability and activity but also provide guidance on how to maximize the usage of Au to optimize the performance of core–shell (Pt) nanoparticles. As a result, such understanding has allowed us to discover a novel NiAu@Pt nanocatalyst for the ORR.

  10. Effect of Au Content on Thermal Stability and Mechanical Properties of Au-Cu-Ag-Si Bulk Metallic Glasses

    NASA Astrophysics Data System (ADS)

    Guo, H.; Zhang, W.; Chen, M. W.; Saotome, Y.; Fukuhara, M.; Inoue, A.

    2011-06-01

    The thermal stability, glass-forming ability (GFA), and mechanical and electrical properties of Au-based Au x Si17Cu75.5- x Ag7.5 ( x = 40 to 75.5 at. pct) metallic glasses were investigated. The glass transition temperature ( T g ) and crystallization temperature ( T x ) decreased with increasing Au content. The ultralow T g values below 373 K (100 °C) were obtained for alloys with x = 55 to 75.5. The alloys with x = 45 to 70 exhibited a high stabilization of supercooled liquid and a high GFA, and the supercooled liquid region and critical sample diameter for glass formation were in the range of 31 K to 50 K and 2 to 5 mm, respectively. The compressive fracture strength ( σ c,f ), Young's modulus ( E), and Vicker's hardness ( H v ) of the bulk metallic glasses (BMGs) decreased with increasing Au content. A linear correlation between Au concentration and the characteristic temperature, i.e., T g and T x , and mechanical properties, i.e., σ c,f , E, and H v , as well as electrical resistivity can be found in the BMGs, which will be helpful for the composition design of the desirable Au-based BMGs with tunable physical properties.

  11. Versatile and efficient catalysts for energy and environmental processes: Mesoporous silica containing Au, Pd and Au-Pd

    NASA Astrophysics Data System (ADS)

    da Silva, Anderson G. M.; Fajardo, Humberto V.; Balzer, Rosana; Probst, Luiz F. D.; Lovón, Adriana S. P.; Lovón-Quintana, Juan J.; Valença, Gustavo P.; Schreine, Wido H.; Robles-Dutenhefner, Patrícia A.

    2015-07-01

    We described a versatile approach for the synthesis of Au/MCM-41, Pd/MCM-41 and Au-Pd/MCM-41 by the direct incorporation of the noble metals into the MCM-41 framework. The structural, textural and chemical properties were characterized by X-ray diffraction (XRD), temperature-programmed reduction (TPR), N2-adsorption (BET and BJH methods), H2-chemisorption, small angle X-ray scattering (SAXS), transmission electron microscope (TEM) and X-ray photoelectron spectroscopy (XPS). The nanomaterials, being comprised of Au, Pd and Au-Pd nanoparticles and possessing high surface areas were applied as versatile and efficient catalysts in benzene, toluene and o-xylene (BTX) oxidation and in the steam reforming of ethanol for hydrogen production. The results revealed that the catalytic behavior in both processes was influenced by the experimental conditions and the nature of the catalyst employed. The Au-Pd/MCM-41 catalyst was the most active in the BTX total oxidation. On the basis of characterization data, it was proposed that the close contact between Pd and Au and the higher dispersion of Pd may be responsible for the enhanced activity of the bimetallic catalyst. However, the strong interaction between the noble metals did not improve the performance of the bimetallic catalyst in ethanol steam reforming, the Pd/MCM-41 catalyst being the most active and selective for hydrogen production.

  12. Rationalization of Au concentration and distribution in AuNi@Pt core-shell nanoparticles for oxygen reduction reaction

    DOE PAGESBeta

    An, Wei; Liu, Ping

    2015-09-18

    Improving the activity and stability of Pt-based core–shell nanocatalysts for proton exchange membrane fuel cells while lowering Pt loading has been one of the big challenges in electrocatalysis. Here, using density functional theory, we report the effect of adding Au as the third element to enhance the durability and activity of Ni@Pt core–shell nanoparticles (NPs) during the oxygen reduction reaction (ORR). Our results show that the durability and activity of a Ni@Pt NP can be finely tuned by controlling Au concentration and distribution. For a NiAu@Pt NP, the durability can be greatly promoted by thermodynamically favorable segregation of Au tomore » replace the Pt atoms at vertex, edge, and (100) facets on the shell, while still keeping the ORR activity on the active Pt(111) shell as high as that of Ni@Pt nanoparticles. Such behavior strongly depends on a direct interaction with the Ni interlayer. The results not only highlight the importance of interplay between surface strain on the shell and the interlayer–shell interaction in determining the durability and activity but also provide guidance on how to maximize the usage of Au to optimize the performance of core–shell (Pt) nanoparticles. As a result, such understanding has allowed us to discover a novel NiAu@Pt nanocatalyst for the ORR.« less

  13. Amperometric immunosensor for carbofuran detection based on MWCNTs/GS-PEI-Au and AuNPs-antibody conjugate.

    PubMed

    Zhu, Ying; Cao, Yaoyao; Sun, Xia; Wang, Xiangyou

    2013-04-19

    In this paper, an amperometric immunosensor for the detection of carbofuran was developed. Firstly, multiwall carbon nanotubes (MWCNTs) and graphene sheets-ethyleneimine polymer-Au (GS-PEI-Au) nanocomposites were modified onto the surface of a glass carbon electrode (GCE) via self-assembly. The nanocomposites can increase the surface area of the GCE to capture a large amount of antibody, as well as produce a synergistic effect in the electrochemical performance. Then the modified electrode was coated with gold nanoparticles-antibody conjugate (AuNPs-Ab) and blocked with BSA. The monoclonal antibody against carbofuran was covalently immobilized on the AuNPs with glutathione as a spacer arm. The morphologies of the GS-PEI-Au nanocomposites and the fabrication process of the immunosensor were characterized by X-ray diffraction (XRD), ultraviolet and visible absorption spectroscopy (UV-vis) and scanning electron microscopy (SEM), respectively. Under optimal conditions, the immunosensor showed a wide linear range, from 0.5 to 500 ng/mL, with a detection limit of 0.03 ng/mL (S/N = 3). The as-constructed immunosensor exhibited notable performance features such as high specificity, good reproducibility, acceptable stability and regeneration performance. The results are mainly due to the excellent properties of MWCNTs, GS-PEI-Au nanocomposites and the covalent immobilization of Ab with free hapten binding sites for further immunoreaction. It provides a new avenue for amperometric immunosensor fabrication.

  14. Heterojunction metal-oxide-metal Au-Fe{sub 3}O{sub 4}-Au single nanowire device for spintronics

    SciTech Connect

    Reddy, K. M. Punnoose, Alex; Hanna, Charles; Padture, Nitin P.

    2015-05-07

    In this report, we present the synthesis of heterojunction magnetite nanowires in alumina template and describe magnetic and electrical properties from a single nanowire device for spintronics applications. Heterojunction Au-Fe-Au nanowire arrays were electrodeposited in porous aluminum oxide templates, and an extensive and controlled heat treatment process converted Fe segment to nanocrystalline cubic magnetite phase with well-defined Au-Fe{sub 3}O{sub 4} interfaces as confirmed by the transmission electron microscopy. Magnetic measurements revealed Verwey transition shoulder around 120 K and a room temperature coercive field of 90 Oe. Current–voltage (I-V) characteristics of a single Au-Fe{sub 3}O{sub 4}-Au nanowire have exhibited Ohmic behavior. Anomalous positive magnetoresistance of about 0.5% is observed on a single nanowire, which is attributed to the high spin polarization in nanowire device with pure Fe{sub 3}O{sub 4} phase and nanocontact barrier. This work demonstrates the ability to preserve the pristine Fe{sub 3}O{sub 4} and well defined electrode contact metal (Au)–magnetite interface, which helps in attaining high spin polarized current.

  15. Amperometric immunosensor for carbofuran detection based on MWCNTs/GS-PEI-Au and AuNPs-antibody conjugate.

    PubMed

    Zhu, Ying; Cao, Yaoyao; Sun, Xia; Wang, Xiangyou

    2013-01-01

    In this paper, an amperometric immunosensor for the detection of carbofuran was developed. Firstly, multiwall carbon nanotubes (MWCNTs) and graphene sheets-ethyleneimine polymer-Au (GS-PEI-Au) nanocomposites were modified onto the surface of a glass carbon electrode (GCE) via self-assembly. The nanocomposites can increase the surface area of the GCE to capture a large amount of antibody, as well as produce a synergistic effect in the electrochemical performance. Then the modified electrode was coated with gold nanoparticles-antibody conjugate (AuNPs-Ab) and blocked with BSA. The monoclonal antibody against carbofuran was covalently immobilized on the AuNPs with glutathione as a spacer arm. The morphologies of the GS-PEI-Au nanocomposites and the fabrication process of the immunosensor were characterized by X-ray diffraction (XRD), ultraviolet and visible absorption spectroscopy (UV-vis) and scanning electron microscopy (SEM), respectively. Under optimal conditions, the immunosensor showed a wide linear range, from 0.5 to 500 ng/mL, with a detection limit of 0.03 ng/mL (S/N = 3). The as-constructed immunosensor exhibited notable performance features such as high specificity, good reproducibility, acceptable stability and regeneration performance. The results are mainly due to the excellent properties of MWCNTs, GS-PEI-Au nanocomposites and the covalent immobilization of Ab with free hapten binding sites for further immunoreaction. It provides a new avenue for amperometric immunosensor fabrication. PMID:23604029

  16. Theoretical investigation of superconductivity in SrAuSi3 and SrAu2Si2

    NASA Astrophysics Data System (ADS)

    Arslan, Enes; Karaca, Ertuǧrul; Tütüncü, H. M.; Başoglu, A.; Srivastava, G. P.

    2016-08-01

    The structural and electronic properties of BaNiSn3-type SrAuSi3 and ThCr2Si2-type SrAu2Si2 have been investigated by using the planewave pseudopotential method and the density functional theory. The electronic structures and phonon dispersion relations of these two materials have been analyzed with and without the inclusion of spin-orbit interaction, and similarities and differences highlighted. By integrating the Eliashberg spectral function α2F(ω), the average electron-phonon coupling parameter is determined to be λ=0.47 for SrAuSi3 and 0.42 for SrAu2Si2. The largest contribution to the electron-phonon coupling for SrAuSi3 comes from the Si p electrons near the Fermi energy and Si-related vibrations. Using a reasonable value of μ* = 0.12 for the effective Coulomb repulsion parameter, the superconducting critical temperature Tc for SrAuSi3 is found to be 1.47 K which compares very well with its experimental value of 1.54 K.

  17. Effect of Au nano-particle aggregation on the deactivation of the AuCl3/AC catalyst for acetylene hydrochlorination

    PubMed Central

    Dai, Bin; Wang, Qinqin; Yu, Feng; Zhu, Mingyuan

    2015-01-01

    A detailed study of the valence state and distribution of the AuCl3/AC catalyst during the acetylene hydrochlorination deactivation process is described and discussed. Temperature-programmed reduction and X-ray photoelectron spectral analysis indicate that the active Au3+ reduction to metallic Au0 is one reason for the deactivation of AuCl3/AC catalyst. Transmission electron microscopy characterization demonstrated that the particle size of Au nano-particles increases with increasing reaction time. The results indicated that metallic Au0 exhibits considerable catalytic activity and that Au nano-particle aggregation may be another reason for the AuCl3/AC catalytic activity in acetylene hydrochlorination. PMID:25994222

  18. Disappearance of back-to-back high p {sub T} hadron correlations in central Au+Au collisions at {radical}s{sub NN} = 200 GeV

    SciTech Connect

    Adler, C.; Ahammed, Z.; Allgower, C.; Amonett, J.; Anderson, B.D.; Anderson, M.; Averichev, G.S.; Balewski, J.; Barannikova, O.; Barnby, L.S.; Baudot, J.; Bekele, S.; Belaga, V.V.; Bellwied, R.; Berger, J.; Bichsel, H.; Billmeier, A.; Bland, L.C.; Blyth, C.O.; Bonner, B.E.; Boucham, A.; Brandin, A.; Bravar, A.; Cadman, R.V.; Caines, H.; Calderon de la Barca Sanchez, M.; Cardenas, A.; Carroll, J.; Castillo, J.; Castro, M.; Cebra, D.; Chaloupka, P.; Chattopadhyay, S.; Chen, Y.; Chernenko, S.P.; Cherney, M.; Chikanian, A.; Choi, B.; Christie, W.; Coffin, J.P.; Cormier, T.M.; Corral, M.M.; Cramer, J.G.; Crawford, H.J.; Derevschikov, A.A.; Didenko, L.; Dietel, T.; 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.; Faivre, J.; Fatemi, R.; Filimonov, K.; Finch, E.; Fisyak, Y.; Flierl, D.; Foley, K.J.; Fu, J.; Gagliardi, C.A.; Gagunashvili, N.; Gans, J.; Gaudichet, L.; Germain, M.; Geurts, F.; Ghazikhanian, V.; Grachov, O.; Grigoriev, V.; Guedon, M.; Gushin, E.; Hallman, T.J.; Hardtke, D.; Harris, J.W.; Henry, T.W.; Heppelmann, S.; Herston, T.; Hippolyte, B.; Hirsch, A.; Hjort, E.; Hoffmann, G.W.; Horsley, M.; Huang, H.Z.; Humanic, T.J.; Igo, G.J.; Ishihara, A.; Ivanshin, Yu.I.; Jacobs, P.; Jacobs, W.W.; Janik, M.; Johnson, I.; Jones, P.G.; Judd, E.G.; Kaneta, M.; Kaplan, M.; Keane, D.; Kiryluk, J.; Kisiel, A.; Klay, J.; Klein, S.R.; Klyachko, A.; Kollegger, T.; Konstantinov, A.S.; Kopytine, M.; Kotchenda, L.; Kovalenko, A.D.; Kramer, M.; Kravtsov, P.; Krueger, K.; Kuhn, C.; Kulikov, A.I.; Kunde, G.J.; Kunz, C.L.; Kutuev, R.Kh.; Kuznetsov, A.A.; Lakehal-Ayat, L.; Lamont, M.A.C.; Landgraf, J.M.; Lange, S.; Lansdell, C.P.; Lasiuk, B.; Laue, F.; Lauret, J.; Lebedev, A.; Lednicky, R.; Leontiev, V.M.; LeVine, M.J.; Li , Q.; Lindenbaum, S.J.; Lisa, M.A.; Liu, F.; Liu, L.; Liu, Z.; Liu, Q.J.; Ljubicic, T.; Llope, W.J.; LoCurto, G.; et al.

    2002-10-25

    Azimuthal correlations for large transverse momentum charged hadrons have been measured over a wide pseudo-rapidity range and full azimuth in Au+Au and p+p collisions at = {radical}s{sub NN} = 200 GeV. The small-angle correlations observed in p+p collisions and at all centralities of Au+Au collisions are characteristic of hard-scattering processes already observed in elementary collisions. A strong back-to-back correlation exists for p+p and peripheral Au + Au. In contrast, the back-to-back correlations are reduced considerably in the most central Au+Au collisions, indicating substantial interaction as the hard-scattered partons or their fragmentation products traverse the medium.

  19. Disappearance of back-to-back high-pT hadron correlations in central Au+Au collisions at sqrt[s NN ] =200 GeV.

    PubMed

    Adler, C; Ahammed, Z; Allgower, C; Amonett, J; Anderson, B D; Anderson, M; Averichev, G S; Balewski, J; Barannikova, O; Barnby, L S; Baudot, J; Bekele, S; Belaga, V V; Bellwied, R; Berger, J; Bichsel, H; Billmeier, A; Bland, L C; Blyth, C O; Bonner, B E; Boucham, A; Brandin, A; Bravar, A; Cadman, R V; Caines, H; Calderón de la Barca Sánchez, M; Cardenas, A; Carroll, J; Castillo, J; Castro, M; Cebra, D; Chaloupka, P; Chattopadhyay, S; Chen, Y; Chernenko, S P; Cherney, M; Chikanian, A; Choi, B; Christie, W; Coffin, J P; Cormier, T M; Corral, M M; Cramer, J G; Crawford, H J; Derevschikov, A A; Didenko, L; Dietel, T; 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; Faivre, J; Fatemi, R; Filimonov, K; Finch, E; Fisyak, Y; Flierl, D; Foley, K J; Fu, J; Gagliardi, C A; Gagunashvili, N; Gans, J; Gaudichet, L; Germain, M; Geurts, F; Ghazikhanian, V; Grachov, O; Grigoriev, V; Guedon, M; Gushin, E; Hallman, T J; Hardtke, D; Harris, J W; Henry, T W; Heppelmann, S; Herston, T; Hippolyte, B; Hirsch, A; Hjort, E; Hoffmann, G W; Horsley, M; Huang, H Z; Humanic, T J; Igo, G; Ishihara, A; Ivanshin, Yu I; Jacobs, P; Jacobs, W W; Janik, M; Johnson, I; Jones, P G; Judd, E G; Kaneta, M; Kaplan, M; Keane, D; Kiryluk, J; Kisiel, A; Klay, J; Klein, S R; Klyachko, A; Kollegger, T; Konstantinov, A S; Kopytine, M; Kotchenda, L; Kovalenko, A D; Kramer, M; Kravtsov, P; Krueger, K; Kuhn, C; Kulikov, A I; Kunde, G J; Kunz, C L; Kutuev, R Kh; Kuznetsov, A A; Lakehal-Ayat, L; Lamont, M A C; Landgraf, J M; Lange, S; Lansdell, C P; Lasiuk, B; Laue, F; Lauret, J; Lebedev, A; Lednický, R; Leontiev, V M; LeVine, M J; Li, Q; Lindenbaum, S J; Lisa, M A; Liu, F; Liu, L; Liu, Z; Liu, Q J; Ljubicic, T; Llope, W J; LoCurto, G; Long, H; Longacre, R S; Lopez-Noriega, M; Love, W A; Ludlam, T; Lynn, D; Ma, J; Magestro, D; Majka, R; Margetis, S; Markert, C; Martin, L; Marx, J; Matis, H S; Matulenko, Yu A; McShane, T S; Meissner, F; Melnick, Yu; Meschanin, A; Messer, M; Miller, M L; Milosevich, Z; Minaev, N G; Mitchell, J; Moore, C F; Morozov, V; de Moura, M M; Munhoz, M G; Nelson, J M; Nevski, P; Nikitin, V A; Nogach, L V; Norman, B; Nurushev, S B; Odyniec, G; Ogawa, A; Okorokov, V; Oldenburg, M; Olson, D; Paic, G; Pandey, S U; Panebratsev, Y; Panitkin, S Y; Pavlinov, A I; Pawlak, T; Perevoztchikov, V; Peryt, W; Petrov, V A; Planinic, M; Pluta, J; Porile, N; Porter, J; Poskanzer, A M; Potrebenikova, E; Prindle, D; Pruneau, C; Putschke, J; Rai, G; Rakness, G; Ravel, O; Ray, R L; Razin, S V; Reichhold, D; Reid, J G; Renault, G; Retiere, F; Ridiger, A; Ritter, H G; Roberts, J B; Rogachevski, O V; Romero, J L; Rose, A; Roy, C; Rykov, V; Sakrejda, I; Salur, S; Sandweiss, J; Savin, I; Schambach, J; Scharenberg, R P; Schmitz, N; Schroeder, L S; Schüttauf, A; Schweda, K; Seger, J; Seliverstov, D; Seyboth, P; Shahaliev, E; Shestermanov, K E; Shimanskii, S S; Simon, F; Skoro, G; Smirnov, N; Snellings, R; Sorensen, P; Sowinski, J; Spinka, H M; Srivastava, B; Stephenson, E J; Stock, R; Stolpovsky, A; Strikhanov, M; Stringfellow, B; Struck, C; Suaide, A A P; Sugarbaker, E; Suire, C; Sumbera, M; Surrow, B; Symons, T J M; Szanto de Toledo, A; Szarwas, P; Tai, A; Takahashi, J; Tang, A H; Thein, D; Thomas, J H; Thompson, M; Tikhomirov, V; Tokarev, M; Tonjes, M B; Trainor, T A; Trentalange, S; Tribble, R E; Trofimov, V; Tsai, O; Ullrich, T; Underwood, D G; Van Buren, G; VanderMolen, A M; Vasilevski, I M; Vasiliev, A N; Vigdor, S E; Voloshin, S A; Wang, F; Ward, H; Watson, J W; Wells, R; Westfall, G D; Whitten, C; Wieman, H; Willson, R; Wissink, S W; Witt, R; Wood, J; Xu, N; Xu, Z; Yakutin, A E; Yamamoto, E; Yang, J; Yepes, P; Yurevich, V I; Zanevski, Y V; Zborovský, I; Zhang, H; Zhang, W M; Zoulkarneev, R; Zubarev, A N

    2003-02-28

    Azimuthal correlations for large transverse momentum charged hadrons have been measured over a wide pseudorapidity range and full azimuth in Au+Au and p+p collisions at sqrt[s(NN)]=200 GeV. The small-angle correlations observed in p+p collisions and at all centralities of Au+Au collisions are characteristic of hard-scattering processes previously observed in high-energy collisions. A strong back-to-back correlation exists for p+p and peripheral Au+Au. In contrast, the back-to-back correlations are reduced considerably in the most central Au+Au collisions, indicating substantial interaction as the hard-scattered partons or their fragmentation products traverse the medium. PMID:12633419

  20. How Can We Understand Au8 Cores and Entangled Ligands of Selenolate- and Thiolate-Protected Gold Nanoclusters Au24(ER)20 and Au20(ER)16 (E = Se, S; R = Ph, Me)? A Theoretical Study.

    PubMed

    Takagi, Nozomi; Ishimura, Kazuya; Matsui, Masafuyu; Fukuda, Ryoichi; Matsui, Toru; Nakajima, Takahito; Ehara, Masahiro; Sakaki, Shigeyoshi

    2015-07-01

    The geometries and electronic structures of selenolate-protected Au nanoclusters, Au24(SeR)20 and Au20(SeR)16, and their thiolate analogues are theoretically investigated with DFT and SCS-MP2 methods, to elucidate the electronic structure of their unusual Au8 core and the reason why they have the unusual entangled "staple-like" chain ligands. The Au8 core is understood to be an [Au4](2+) dimer in which the [Au4](2+) species has a tetrahedral geometry with a closed-shell singlet ground state. The SCS-MP2 method successfully reproduced the distance between two [Au4](2+) moieties, but the DFT with various functionals failed it, suggesting that the dispersion interaction is crucial between these two [Au4](2+) moieties. The SCS-MP2-calculated formation energies of these nanocluster compounds indicate that the thiolate staple-like chain ligands are more stable than the selenolate ones, but the Au8 core more strongly coordinates with the selenolate staple-like chain ligands than with the thiolate ones. Though Au20(SeR)16 has not been reported yet, its formation energy is calculated to be large, suggesting that this compound can be synthesized as a stable species if the concentration of Au(SeR) is well adjusted. The aurophilic interactions between the staple-like chain ligands and between the Au8 core and the staple-like chain ligand play an important role for the stability of these compounds. Because of the presence of this autophilic interaction, Au24(SeR)20 is more stable than Au20(SeR)16 and the unusual entangled ligands are involved in these compounds. PMID:26076323

  1. Formation, Migration, and Reactivity of Au CO Complexes on Gold Surfaces

    DOE PAGESBeta

    Wang, Jun; McEntee, Monica; Tang, Wenjie; Neurock, Matthew; Baddorf, Arthur P.; Maksymovych, Petro; Yates, Jr, John T.

    2016-01-12

    Here, we report experimental as well as theoretical evidence that suggests Au CO complex formation upon the exposure of CO to active sites (step edges and threading dislocations) on a Au(111) surface. Room-temperature scanning tunneling microscopy (STM), X-ray photoelectron spectroscopy, transmission infrared spectroscopy, and density functional theory calculations point to Au CO complex formation and migration. Room-temperature STM of the Au(111) surface at CO pressures in the range from 10^ 8 to 10^ 4 Torr (dosage up to 10^6 langmuir) indicates Au atom extraction from dislocation sites of the herringbone reconstruction, mobile Au CO complex formation and diffusion, and Aumore » adatom cluster formation on both elbows and step edges on the Au surface. The formation and mobility of the Au CO complex result from the reduced Au Au bonding at elbows and step edges leading to stronger Au CO bonding and to the formation of a more positively charged CO (CO +) on Au. These studies indicate that the mobile Au CO complex is involved in the Au nanoparticle formation and reactivity, and that the positive charge on CO increases due to the stronger adsorption of CO at Au sites with lower coordination numbers.« less

  2. Enantiospecific adsorption of cysteine on a chiral Au34 cluster

    NASA Astrophysics Data System (ADS)

    de Jesús Pelayo, José; Valencia, Israel; Díaz, Gabriela; López-Lozano, Xóchitl; Garzón, Ignacio L.

    2015-12-01

    The interaction of biological molecules like chiral amino acids with chiral metal clusters is becoming an interesting and active field of research because of its potential impact in, for example, chiral molecular recognition phenomena. In particular, the enantiospecific adsorption (EA) of cysteine (Cys) on a chiral Au55 cluster was theoretically predicted a few years ago. In this work, we present theoretical results, based on density functional theory, of the EA of non-zwitterionic cysteine interacting with the C3-Au34 chiral cluster, which has been experimentally detected in gas phase, using trapped ion electron diffraction. Our results show that, indeed, the adsorption energy of the amino acid depends on which enantiomers participate in the formation Cys-Au34 chiral complex. EA was obtained in the adsorption modes where both the thiol, and the thiol-amino functional groups of Cys are adsorbed on low-coordinated sites of the metal cluster surface. Similarly to what was obtained for the Cys-Au55 chiral complex, in the present work, it is found that the EA is originated from the different strength and location of the bond between the COOH functional group and surface Au atoms of the Au34 chiral cluster. Calculations of the vibrational spectrum for the different Cys-Au34 diastereomeric complexes predict the existence of a vibro-enantiospecific effect, indicating that the vibrational frequencies of the adsorbed amino acid depend on its handedness. Contribution to the Topical Issue "Atomic Cluster Collisions (7th International Symposium)", edited by G. Delgado Barrio, A. Solov'Yov, P. Villarreal, R. Prosmiti.

  3. Thiol ligand-induced transformation of Au38(SC2H4Ph)24 to Au36(SPh-t-Bu)24.

    PubMed

    Zeng, Chenjie; Liu, Chunyan; Pei, Yong; Jin, Rongchao

    2013-07-23

    We report a disproportionation mechanism identified in the transformation of rod-like biicosahedral Au38(SCH2CH2Ph)24 to tetrahedral Au36(TBBT)24 nanoclusters. Time-dependent mass spectrometry and optical spectroscopy analyses unambiguously map out the detailed size-conversion pathway. The ligand exchange of Au38(SCH2CH2Ph)24 with bulkier 4-tert-butylbenzenethiol (TBBT) until a certain extent starts to trigger structural distortion of the initial biicosahedral Au38(SCH2CH2Ph)24 structure, leading to the release of two Au atoms and eventually the Au36(TBBT)24 nanocluster with a tetrahedral structure, in which process the number of ligands is interestingly preserved. The other product of the disproportionation process, i.e., Au40(TBBT)m+2(SCH2CH2Ph)24-m, was concurrently observed as an intermediate, which was the result of addition of two Au atoms and two TBBT ligands to Au38(TBBT)m(SCH2CH2Ph)24-m. The reaction kinetics on the Au38(SCH2CH2Ph)24 to Au36(TBBT)24 conversion process was also performed, and the activation energies of the structural distortion and disproportionation steps were estimated to be 76 and 94 kJ/mol, respectively. The optical absorption features of Au36(TBBT)24 are interpreted on the basis of density functional theory simulations.

  4. A simple electrochemical biosensor based on AuNPs/MPS/Au electrode sensing layer for monitoring carbamate pesticides in real samples.

    PubMed

    Song, Yonghai; Chen, Jingyi; Sun, Min; Gong, Coucong; Shen, Yuan; Song, Yonggui; Wang, Li

    2016-03-01

    A simple electrochemical biosensor for quantitative determination of carbamate pesticide was developed based on a sensing interface of citrate-capped gold nanoparticles (AuNPs)/(3-mercaptopropyl)-trimethoxysilane (MPS)/gold electrode (Au). The biosensor was fabricated by firstly assembling three-dimensional (3D) MPS networks on Au electrode and subsequently assembling citrate-capped AuNPs on 3D MPS network via AuS bond. The interface of AuNPs/MPS/Au was negatively charged originating from the citrate coated on AuNPs that would repulse the negatively charged ferricyanide ([Fe(CN)6](3-/4-)) to produce a negative response. In the presence of acetylcholinesterase (AChE) and acetylthiocholine (ATCl), the AChE catalyzes the hydrolysis of ATCl into positively charged thiocholine which would replace the citrate on AuNPs through the strong AuS bond and convert the negative charged surface to be positively charged. The resulted positively charged AuNPs/MPS/Au then attracted the [Fe(CN)6](3-/4-) to produce a positive response. Based on the inhibition of carbamate pesticides on the activity of AChE, the pesticide could be quantitatively determined at a very low potential. The linear range was from 0.003 to 2.00 μM. The sensing platform was also proved to be suitable for carbamate pesticides detection in practical sample.

  5. The characteristics of solar wind magnetic field during the negative-AU and large-AU (>1200nT) events

    NASA Astrophysics Data System (ADS)

    Lyu, L. H.; Kao, W.

    2014-12-01

    The negative-AU events are relatively unusual, which have caught our attention. To understand the cause of negative AU, we first eliminate the ring-current effect by considering only the events with AUAU has strong negative Bz and By components during these negative-AU events. We also found that one of the negative AU events has been reported by Feldstein et al. (2006). They associated the enhancement of westward electric jet by the negative IMF-By component based on previous models obtained independently by Friis-Christensen et al. (1972) and Sumaruk & Feldstein (1973). Enhancement of electric jet in opposite direction is expected to be found when the IMF-By is positive. To verify their models we also examine the strong AU events with AU > 1200nT. We found that these large-AU events are associated with IMF-Bz<0 and IMF-By >0. Both negative-AU and large-AU events tend to occur during the beginning of the main phase of a strong magnetic storm with Kp= 7~9. The enhancement of Cowling electrojet has been proposed by Kan et al. (2011) for the triggering of substorm onset. We will discuss the possibility that a similar enhancement process might take place in the dayside auroral oval during these extreme AU events.

  6. Effects of stretching and compression on conducting properties of an Au-alkanedithiol-Au molecular junction

    NASA Astrophysics Data System (ADS)

    Xie, Fang; Zhang, Xiao-Jiao; Yu, Ji-Hai; Xu, Hua; Chu, Yu-Fang; Fan, Zhi-Qiang

    2016-03-01

    We have studied the effects of stretching and compression on the electronic properties of 7-alkanedithiol covalently linked to two Au electrodes. Results show a progressive increase in conductivity upon molecule compression and decrease with molecule stretching. The notable conductance increase at high compression is attributed to a significant modification of HOMO and LUMO orbitals of the junction, which enhances electron delocalization and promotes tunneling across the junction. More important, the current switching ratios between the various stages of compressed/extended geometries almost maintain the constant values on the bias region from 0 V to 2 V. In other word, the mechanically-induced conductance enhancement and weakening are stable within a large bias voltage range.

  7. Drowned reefs and antecedent karst topography, Au'au channel, S.E. Hawaiian Islands

    USGS Publications Warehouse

    Grigg, R.W.; Grossman, E.E.; Earle, S.A.; Gittings, S.R.; Lott, D.; McDonough, J.

    2002-01-01

    During the last glacial maximum (LGM), about 21,000 years ago, the Hawaiian Islands of Maui, Lanai, and Molokai were interconnected by limestone bridges, creating a super-island known as Maui-Nui. Approximately 120 m of sea-level rise during the Holocene Transgression flooded, and then drowned, these bridges separating the islands by inter-island channels. A new multibeam high-resolution bathymetric survey of the channels between the islands, coupled with observations and video-transects utilizing DeepWorker-2000 submersibles, has revealed the existence of numerous drowned reef features including concentric solution basins, solution ridges (rims), sand and sediment plains, and conical-shaped reef pinnacles. The concentric basins contain flat lagoon-like bottoms that are rimmed by steep-sided limestone walls. Undercut notches rim the basins at several depths, marking either sea-level still stands or paleo-lake levels. All of the solution basins shallower than 120 m were subaerial at the LGM, and at one stage or another may have been shallow shoreline lakes. Today, about 70 drowned reef pinnacles are scattered across the Maui-Lanai underwater bridge and all are situated in wave-sheltered positions. Most drowned during the interval between 14,000 and 10,000 years ago when sea-level rise averaged 15 mm/year. Virtually all of the surficial topography in the Au'au Channel today is a product of karst processes accentuated by marginal reef growth during the Holocene. Both the submerged basins and the drowned reefs represent an archive of sea-level and climate history in Hawaii during the late Quaternary.

  8. Dielectron production in Au plus Au collisions at root s(NN)=200 GeV

    SciTech Connect

    Adare, A.; Awes, Terry C; Cianciolo, Vince; Efremenko, Yuri V; Enokizono, A.; Silvermyr, D.; Sorensen, Soren P; Stankus, Paul W; Young, Glenn R; PHENIX, Collaboration [

    2016-01-01

    We present measurements of e(+)e-production at midrapidity in Au + Au collisions at root s(NN) = 200 GeV. The invariant yield is studied within the PHENIX detector acceptance over a wide range of mass (m(ee) < 5 GeV/c(2)) and pair transverse momentum (p(T) < 5 GeV/c) for minimum bias and for five centrality classes. The e(+)e(-) yield is compared to the expectations from known sources. In the low-mass region (m(ee) = 0.30-0.76 GeV/c(2)) there is an enhancement that increases with centrality and is distributed over the entire pair p(T) range measured. It is significantly smaller than previously reported by the PHENIX experiment and amounts to 2.3 +/- 0.4(stat) +/- 0.4(syst) +/- 0.2(model) or to 1.7 +/- 0.3(stat) +/- 0.3(syst) +/- 0.2(model) for minimum bias collisions when the open heavy-flavor contribution is calculated with PYTHIA or MC@NLO, respectively. The inclusive mass and p(T) distributions, as well as the centrality dependence, are well reproduced by model calculations where the enhancement mainly originates from the melting of the rho meson resonance as the system approaches chiral symmetry restoration. In the intermediate-mass region (m(ee) = 1.2-2.8 GeV/c(2)), the data hint at a significant contribution in addition to the yield from the semileptonic decays of heavy-flavor mesons.

  9. Dielectron production in Au plus Au collisions at root s(NN)=200 GeV

    DOE PAGESBeta

    Adare, A.; Awes, Terry C; Cianciolo, Vince; Efremenko, Yuri V; Enokizono, A.; Read, K. F.; Silvermyr, D.; Sorensen, Soren P; Stankus, Paul W; Young, Glenn R; et al

    2016-01-01

    We present measurements of e(+)e-production at midrapidity in Au + Au collisions at root s(NN) = 200 GeV. The invariant yield is studied within the PHENIX detector acceptance over a wide range of mass (m(ee) < 5 GeV/c(2)) and pair transverse momentum (p(T) < 5 GeV/c) for minimum bias and for five centrality classes. The e(+)e(-) yield is compared to the expectations from known sources. In the low-mass region (m(ee) = 0.30-0.76 GeV/c(2)) there is an enhancement that increases with centrality and is distributed over the entire pair p(T) range measured. It is significantly smaller than previously reported by themore » PHENIX experiment and amounts to 2.3 +/- 0.4(stat) +/- 0.4(syst) +/- 0.2(model) or to 1.7 +/- 0.3(stat) +/- 0.3(syst) +/- 0.2(model) for minimum bias collisions when the open heavy-flavor contribution is calculated with PYTHIA or MC@NLO, respectively. The inclusive mass and p(T) distributions, as well as the centrality dependence, are well reproduced by model calculations where the enhancement mainly originates from the melting of the rho meson resonance as the system approaches chiral symmetry restoration. In the intermediate-mass region (m(ee) = 1.2-2.8 GeV/c(2)), the data hint at a significant contribution in addition to the yield from the semileptonic decays of heavy-flavor mesons.« less

  10. Intriguing centrality dependence of the Au-Au source size at the AGS

    SciTech Connect

    Baker, M.D.; The E802 Collaboration

    1996-06-01

    One of the main goals of high energy heavy ion physics is to establish the existence of a deconfined phase of nuclear matter--the quark-gluon plasma--at high temperatures or densities. One possible signature of such a phase transition, especially if it were first order, would be a larger source size or lifetime than a similar hadronic system. At current AGS energies, we attempt to form a quark- gluon plasma by achieving a high baryon density for a period of time in the center of the collision region. For a given density threshold, the size of this high density region should be a strong function of the impact parameter: the more central the event, the larger the high density region. Therefore, one possible signature of a quark-gluon plasma would be a sudden change in system lifetime or size as a function of the centrality of the collision. In this talk we present an intriguing effect which was not predicted for simple hadronic systems: a rapid increase of the HBT-measured source radius parameter for pion pairs with increasing centrality for Au-Au collisions at a beam momentum of 11.45 A GeV/c on a fixed target. Experience has shown, however, that we must be cautious in our interpretation. A complete understanding of the collision dynamics at a given energy must be built up from several measurements and new, but conventional, hadronic explanations must be considered for such unexpected effects. More study is needed, therefore, before any strong conclusions can be reached.

  11. Herringbone and triangular patterns of dislocations in Ag, Au, and AgAu alloy films on Ru(0001).

    SciTech Connect

    Thayer, Gayle Echo; de la Figuera, Juan; Bartelt, Norman Charles; Carter, C. Barrington; Hwang, R. Q.; Thurmer, Konrad; Ling, W. L.; Hamilton, John C.; McCarty, Kevin F.

    2008-10-01

    We have studied the dislocation structures that occur in films of Ag, Au, and Ag{sub 0.5}Au{sub 0.5} alloy on a Ru(0001) substrate. Monolayer (ML) films form herringbone phases while films two or more layers thick contain triangular patterns of dislocations. We use scanning tunneling microscopy (STM) and low-energy electron diffraction (LEED) to determine how the film composition affects the structure and periodicity of these ordered structures. One layer of Ag forms two different herringbone phases depending on the exact Ag coverage and temperature. Low-energy electron microscopy (LEEM) establishes that a reversible, first-order phase transition occurs between these two phases at a certain temperature. We critically compare our 1 ML Ag structures to conflicting results from an X-ray scattering study [H. Zajonz et al., Phys. Rev. B 67 (2003) 155417]. Unlike Ag, the herringbone phases of Au and AgAu alloy are independent of the exact film coverage. For two layer films in all three systems, none of the dislocations in the triangular networks thread into the second film layer. In all three systems, the in-plane atomic spacing of the second film layer is nearly the same as in the bulk. Film composition does, however, affect the details of the two layer structures. Ag and Au films form interconnected networks of dislocations, which we refer to as 'trigons.' In 2 ML AgAu alloy, the dislocations form a different triangular network that shares features of both trigon and moire structures. Yet another well-ordered structure, with square symmetry, forms at the boundaries of translational trigon domains in 2 ML Ag films but not in Au films.

  12. Observations of high spin states in {sup 179}Au

    SciTech Connect

    Carpenter, M.P.; Ahmad, I.; Blumenthal, D.J.

    1995-08-01

    As part of a current study on the properties of the {pi} i{sub 13/2} intruder state in the A = 175-190 region, we conducted an experiment at ATLAS to observe high spin states in {sup 179}Au utilizing the reaction {sup 144}Sm({sup 40}Ar,p4n) at beam energies of 207 MeV and 215 MeV. To aid in the identification of {sup 179}Au, and to filter out the large amount of events from fission by-products, the Fragment Mass Analyzer was utilized in conjunction with ten Compton-suppression germanium detectors. In total, 11 x 10{sup 6} {gamma}-{gamma} and 4 x 10{sup 5} {gamma}-recoil events were collected. By comparing {gamma}-rays in coincidence with an A = 179 recoil mass gate and {gamma}-rays in coincidence with Au K{alpha} and K{beta} X-rays, ten {gamma}-rays were identified as belonging to {sup 179}Au. Based on {gamma}-ray coincidence relationships and on comparisons with neighboring odd-A Au nuclei, we constructed a tentative level scheme and assigned a rotational-like sequence to the {pi} i{sub 13/2} proton configuration.

  13. Au/metal oxides for low temperature CO oxidation

    SciTech Connect

    Srinivas, G.; Wright, J.; Bai, C.S.; Cook, R.

    1996-12-31

    Oxidation of carbon monoxide is important for several operations including fuel cells and carbon dioxide lasers. Room temperature CO oxidation has been investigated on a series of Au/metal oxide catalysts at conditions typical of spacecraft atmospheres; CO = 50 ppm, CO{sub 2} = 7,000 ppm, H{sub 2}O = 40% (RH) at 25{degrees}C, balance = air, and gas hourly space velocities of 7,000-60,000 hr{sup -1}. The addition of Au increases the room temperature CO oxidation activity of the metal oxides dramatically. All the Au/metal oxides deactivate during the CO oxidation reaction, especially in the presence of CO{sub 2} in the feed. The stability of the Au/metal oxide catalysts decreases in the following order: TiO{sub 2} > Fe{sub 2}O{sub 3} > NiO > Co{sub 3}O{sub 4}. The stability appears to decrease with an increase in the basicity of the metal oxides. In situ FTIR of CO adsorption on Au/TiO{sub 2} at 25{degrees}C indicates the formation of adsorbed CO, carboxylate, and carbonate species on the catalyst surface.

  14. Au nanoinjectors for electrotriggered gene delivery into the cell nucleus.

    PubMed

    Kang, Mijeong; Kim, Bongsoo

    2015-01-01

    Intracellular delivery of exogenous materials is an essential technique required for many fundamental biological researches and medical treatments. As our understanding of cell structure and function has been improved and diverse therapeutic agents with a subcellular site of action have been continuously developed, there is a demand to enhance the performance of delivering devices. Ideal intracellular delivery devices should convey various kinds of exogenous materials without deteriorating cell viability regardless of cell type and, furthermore, precisely control the location and the timing of delivery as well as the amount of delivered materials for advanced researches.In this chapter the development of a new intracellular delivery device, a nanoinjector made of a Au (gold) nanowire (a Au nanoinjector) is described in which delivery is triggered by external application of an electric pulse. As a model study, a gene was delivered directly into the nucleus of a neuroblastoma cell, and successful delivery without cell damage was confirmed by the expression of the delivered gene. The insertion of a Au nanoinjector directly into a cell can be generally applied to any kind of cell, and a high degree of surface modification of Au allows attachment of diverse materials such as proteins, small molecules, or nanoparticles as well as genes on Au nanoinjectors. This expands their applicability, and it is expected that they will provide important information on the effects of delivered exogenous materials and consequently contribute to the development of related therapeutic or clinical technologies.

  15. Extraordinary epitaxial alignment of graphene islands on Au(111)

    NASA Astrophysics Data System (ADS)

    Wofford, Joseph M.; Starodub, Elena; Walter, Andrew L.; Nie, Shu; Bostwick, Aaron; Bartelt, Norman C.; Thürmer, Konrad; Rotenberg, Eli; McCarty, Kevin F.; Dubon, Oscar D.

    2012-05-01

    Pristine, single-crystalline graphene displays a unique collection of remarkable electronic properties that arise from its two-dimensional, honeycomb structure. Using in situ low-energy electron microscopy, we show that when deposited on the (111) surface of Au carbon forms such a structure. The resulting monolayer, epitaxial film is formed by the coalescence of dendritic graphene islands that nucleate at a high density. Over 95% of these islands can be identically aligned with respect to each other and to the Au substrate. Remarkably, the dominant island orientation is not the better lattice-matched 30° rotated orientation but instead one in which the graphene [01] and Au [011] in-plane directions are parallel. The epitaxial graphene film is only weakly coupled to the Au surface, which maintains its reconstruction under the slightly p-type doped graphene. The linear electronic dispersion characteristic of free-standing graphene is retained regardless of orientation. That a weakly interacting, non-lattice matched substrate is able to lock graphene into a particular orientation is surprising. This ability, however, makes Au(111) a promising substrate for the growth of single crystalline graphene films.

  16. Polarization properties of fluorescent BSA protected Au25 nanoclusters.

    PubMed

    Raut, Sangram; Chib, Rahul; Rich, Ryan; Shumilov, Dmytro; Gryczynski, Zygmunt; Gryczynski, Ignacy

    2013-04-21

    BSA protected gold nanoclusters (Au25) are attracting a great deal of attention due to their unique spectroscopic properties and possible use in biophysical applications. Although there are reports on synthetic strategies, spectroscopy and applications, little is known about their polarization behavior. In this study, we synthesized the BSA protected Au25 nanoclusters and studied their steady state and time resolved fluorescence properties including polarization behavior in different solvents: glycerol, propylene glycol and water. We demonstrated that the nanocluster absorption spectrum can be separated from the extinction spectrum by subtraction of Rayleigh scattering. The nanocluster absorption spectrum is well approximated by three Gaussian components. By a comparison of the emissions from BSA Au25 clusters and rhodamine B in water, we estimated the quantum yield of nanoclusters to be higher than 0.06. The fluorescence lifetime of BSA Au25 clusters is long and heterogeneous with an average value of 1.84 μs. In glycerol at -20 °C the anisotropy is high, reaching a value of 0.35. However, the excitation anisotropy strongly depends on the excitation wavelengths indicating a significant overlap of the different transition moments. The anisotropy decay in water reveals a correlation time below 0.2 μs. In propylene glycol the measured correlation time is longer and the initial anisotropy depends on the excitation wavelength. BSA Au25 clusters, due to long lifetime and high polarization, can potentially be used in studying large macromolecules such as protein complexes with large molecular weight.

  17. Synthesis and characterization of Ni-Au bimetallic nanoparticles

    NASA Astrophysics Data System (ADS)

    Nik Roselina, N. R.; Azizan, A.; Hyie, Koay Mei; Murad, Mardziah Che; Abdullah, Abdul Hakim

    2015-04-01

    Bimetallic structure of nanoparticles is of great interest due to their extraordinary properties, especially in combining the specialty of the core and its shell. This work reports the effect of pH on the synthesis of Ni-Au (nickel-gold) bimetallic nanoparticles. The synthesis involves a two-step process where Ni nanoparticles were first synthesized using polyol method with hydrazine as the reducing agent. This was followed by the process of reducing AuCl4- to Au in the solution containing pre-prepared Ni to form Ni-Au bimetallic nanoparticles using sodium citrate as the reducing agent. The results obtained from Transmission Electron Microscopy (TEM) show that the process can possibly produce either core-shell structure, or mixture of Ni and Au nanoparticles. Magnetic property of core-shell structure investigated using Vibrating Sample Magnetometer (VSM) demonstrated typical characteristic of ferromagnetic with an increased magnetization as compared to Ni nanoparticles. The saturation magnetization (Ms) and coercivity (Hc) were obtained as 19.1 emu/g and 222.3 Oe, respectively.

  18. The Brown Dwarf Desert at 75-1200 AU

    NASA Astrophysics Data System (ADS)

    McCarthy, C.; Zuckerman, B.

    2004-05-01

    We present results of a comprehensive infrared coronagraphic search for substellar companions to nearby stars. The research consisted of (1) a 178-star survey at Steward and Lick observatories, with optical follow-up from Keck Observatory, capable of detecting companions with masses greater than 30 MJ, and semimajor axes between about 140 to 1200 AU; (2) a 102-star survey using the Keck Telescope, capable of detecting extrasolar brown dwarfs and planets typically more massive than 10 MJ, with semimajor axes between about 75 and 300 AU. Only one brown dwarf companion was detected, and no planets. The frequency of brown dwarf companions to G, K, and M stars orbiting between 75 and 300 AU is measured to be 1%+/-1%, the most precise measurement of this quantity to date. The frequency of massive (greater than 30 MJ) brown dwarf companions at 120-1200 AU is found to be f=0.7%+/-0.7%. The frequency of giant planet companions with masses between 5 and 10 MJ orbiting between 75 and 300 AU is measured here for the first time to be no more than ~3%. Together with other surveys that encompass a wide range of orbital separations, these results imply that substellar objects with masses between 12 and 75 MJ form only rarely as companions to stars. Theories of star formation that could explain these data are only now beginning to emerge.

  19. The Brown Dwarf Desert at 75-1200 AU

    NASA Astrophysics Data System (ADS)

    McCarthy, C.; Zuckerman, B.

    2004-05-01

    We present results of a comprehensive infrared coronagraphic search for substellar companions to nearby stars. The research consisted of: 1.) a 178 star survey at Steward and Lick Observatories, with optical followup from Keck Observatory, capable of detecting companions with masses greater than 30 MJupiter, and semi-major axes between about 140 to 1200 AU. 2.) a 102 star survey using the Keck telescope, capable of detecting extrasolar brown dwarfs and planets typically more massive than 10 MJupiter, with semi-major axes between about 75 and 300 AU. Only one brown dwarf companion was detected, and zero planets. The frequency of brown dwarf companions to G, K & M stars orbiting between 75 and 300 AU is measured to be 1±1%, the most precise measurement of this quantity to date. The frequency of massive (> 30MJupiter) brown dwarf companions at 120-1200 AU is found to be 0.7±0.7%. The frequency of giant planet companions with masses between 5 and 10 MJupiter orbiting between 75 and 300 AU is measured here for the first time to be no more than ˜ 3%. Together with other surveys that encompass a wide range of orbital separations, these results imply that substellar objects with masses between 12 and 75 MJupiter form only rarely as companions to stars. Theories of star formation which could explain these data are only now beginning to emerge. We acknowledge support from NASA Astrobiology Institute.

  20. HELIUM ION ANISOTROPIES IN COROTATING INTERACTION REGIONS AT 1 AU

    SciTech Connect

    Ebert, R. W.; Desai, M. I.; Dayeh, M. A.; Mason, G. M.

    2012-08-01

    We investigated the first-order flow anisotropies in the solar wind frame of {approx}0.06-0.95 MeV nucleon{sup -1} He ions during three corotating interaction region (CIR)-associated particle intensity enhancements observed at 1 AU by Wind, examining CIRs with (1) a reverse shock, (2) a well-formed compression region, and (3) a weak compression region. We identified anti-sunward flows in the compression region downstream of the CIR trailing edge in the events with a reverse shock and well-formed compression that transitioned to sunward flows across and upstream of this boundary. These observations suggest that the trailing edge is organizing the He ion flows and is a local source for the particles in these events, this source being inside 1 AU prior to the trailing edge arrival and beyond 1 AU after its passage. The event with the weak compression region had predominantly sunward flows throughout, indicating that the source of the He ions was beyond 1 AU. These observations provide compelling evidence that He ions at 1 AU can be accelerated to suprathermal energies at the CIR trailing edge in events where the compression region is well formed.

  1. Structure of SiAu16: Can a silicon atom be stabilized in a gold cage?

    NASA Astrophysics Data System (ADS)

    Sun, Qiang; Wang, Qian; Chen, Gang; Jena, Puru

    2007-12-01

    Nanostructures of Au and Si as well as Au-Si hybrid structures are topics of great current interest from both scientific and technological points of view. Recent discovery of Au clusters having fullerenelike geometries and the possibility of endohedral complexes with Si atoms inside the Au cage opens new possibilities for designing Au-Si nanostructures. Using ab initio simulated annealing method we have examined the stability of Si -Au16 endohedral complex. Contrary to what we believed, we find that the endohedral configuration is metastable and the structure where Si atom binds to the exterior surface of the Au16 cage is the lowest energy structure. The bonding of Si to Au cluster mimics its behavior of that in bulk and liquid phase of Au. In addition, doping of Si in high concentration would cause fracture and embrittlement in gold nanostructures just as it does in the bulk phase. Covalent bonding between Au-Au and Au-Si is found to be a dominant feature in the stability of the Au-Si nanostructures. Our study provides insight that may be useful in fabricating hybrid Au-Si nanostructures for applications microelectronics, catalysis, biomedine, and jewelry industry.

  2. Study on antibacterial activity of chemically synthesized PANI-Ag-Au nanocomposite

    NASA Astrophysics Data System (ADS)

    Boomi, Pandi; Prabu, Halliah Gurumallesh; Manisankar, Paramasivam; Ravikumar, Sundaram

    2014-05-01

    Pristine polyaniline (PANI), PANI-Ag, PANI-Au and PANI-Ag-Au nanocomposites have been successfully synthesized by chemical oxidative polymerization method using aniline as monomer, ammonium persulphate as oxidant and metal (Ag, Au and Ag-Au) colloids. UV-Vis analysis exhibited surface Plasmon resonances of Ag, Au, Ag-Au nanoparticles. FT-IR spectra revealed the shift in peak position of N-H stretching. X-ray diffraction (XRD) results confirm the presence of Ag, Au and Au-Ag nanoparticles. HR-TEM images show nanosizes of Ag, Au, Ag-Au and the incorporation of such nanoparticles into the PANI matrix. Pristine PANI, PANI-Ag, PANI-Au and PANI-Ag-Au nanocomposites were tested for antibacterial activity by agar well diffusion method. PANI-Ag-Au nanocomposite exhibited higher antibacterial activity against both gram-positive [Streptococcus sp. (MTCC 890), Staphylococcus sp. (MTCC 96)] and gram-negative bacteria [Escherichia coli (MTCC 1671) and Klebsiella sp. (MTCC 7407)] when compared with PANI-Ag nanocomposite, PANI-Au nanocomposite and pristine PANI. The novelty of this study is the polymer-bimetal synthesis and its antibacterial potential.

  3. 2-Thiopheneacetic acid directed synthesis of Au nanorosette as an SERS-active substrate.

    PubMed

    Shin, Hye-Seon; Hong, Jin-Yeon; Huh, Seong

    2013-02-01

    Rosette-like nanoscale Au materials were simply prepared through one-pot reduction of the AuCl₄⁻ precursor by 2-thiopheneacetic acid (2-TAA) without extra surface capping ligands at room temperature. 2-TAA underwent polymerization into polythiophene derivatives while the AuCl₄⁻ precursor was simultaneously reduced into various Au nanostructures. In situ generated polythiophene derivatives played a significant role of surface passivation in guiding the shape of Au nanostructures. The morphology of Au nanostructures was strongly dependent on the molar ratio of 2-TAA to AuCl₄⁻. At lower [2-TAA]/[AuCl₄⁻] ratios, uniform rosette-like Au microparticles consisting of 30-nm-thick Au nanoplates were observed. The Au nanoplates had either triangular prismatic or hexagonal geometry with many defects. Uniform Au nanorosettes could be easily deposited on the Si substrate by drop-casting and were subsequently used as highly active SERS substrates for the detection of methylene blue and crystal violet by Raman spectroscopy. Upon increasing the ratio of [2-TAA]/[AuCl₄⁻], Au nanoparticles or nanorods heavily surrounded with polythiophene polymers were obtained. PMID:23336301

  4. Atomic and electronic structures of Si(1 1 1)-(√3 x √3)R30°-Au and (6 × 6)-Au surfaces.

    PubMed

    Patterson, C H

    2015-12-01

    Si(1 1 1)-Au surfaces with around one monolayer of Au exhibit many ordered structures and structures containing disordered domain walls. Hybrid density functional theory (DFT) calculations presented here reveal the origin of these complex structures and tendency to form domain walls. The conjugate honeycomb chain trimer (CHCT) structure of the [Formula: see text]-Au phase contains Si atoms with non-bonding surface states which can bind Au atoms in pairs in interstices of the CHCT structure and make this surface metallic. Si adatoms adsorbed on the [Formula: see text]-Au surface induce a gapped surface through interaction with the non-bonding states. Adsorption of extra Au atoms in interstitial sites of the [Formula: see text]-Au surface is stabilized by interaction with the non-bonding orbitals and leads to higher coverage ordered structures including the [Formula: see text]-Au phase. Extra Au atoms bound in interstitial sites of the [Formula: see text]-Au surface result in top layer Si atoms with an SiAu4 butterfly wing configuration. The structure of a [Formula: see text]-Au phase, whose in-plane top atomic layer positions were previously determined by an electron holography technique (Grozea et al 1998 Surf. Sci. 418 32), is calculated using total energy minimization. The Patterson function for this structure is calculated and is in good agreement with data from an in-plane x-ray diffraction study (Dornisch et al 1991 Phys. Rev. B 44 11221). Filled and empty state scanning tunneling microscopy (STM) images are calculated for domain walls and the [Formula: see text]-Au structure. The [Formula: see text]-Au phase is 2D chiral and this is evident in computed and actual STM images. [Formula: see text]-Au and domain wall structures contain the SiAu4 motif with a butterfly wing shape. Chemical bonding within the Si-Au top layers of the [Formula: see text]-Au and [Formula: see text]-Au surfaces is analyzed and an explanation for the SiAu4 motif structure is given.

  5. Level densities and thermodynamical properties of Pt and Au isotopes

    NASA Astrophysics Data System (ADS)

    Giacoppo, F.; Bello Garrote, F. L.; Bernstein, L. A.; Bleuel, D. L.; Eriksen, T. K.; Firestone, R. B.; Görgen, A.; Guttormsen, M.; Hagen, T. W.; Kheswa, B. V.; Klintefjord, M.; Koehler, P. E.; Larsen, A. C.; Nyhus, H. T.; Renstrøm, T.; Sahin, E.; Siem, S.; Tornyi, T.

    2014-11-01

    The nuclear level densities of Pt-196194 and Au,198197 below the neutron separation energy have been measured using transfer and scattering reactions. All the level density distributions follow the constant-temperature description. Each group of isotopes is characterized by the same temperature above the energy threshold corresponding to the breaking of the first Cooper pair. A constant entropy excess Δ S =1.9 kB and 1.1 kB is observed in 195Pt and 198Au with respect to 196Pt and 197Au, respectively, giving information on the available single-particle level space for the last unpaired valence neutron. The breaking of nucleon Cooper pairs is revealed by sequential peaks in the microcanonical caloric curve.

  6. Controlled electrodeposition of Au monolayer film on ionic liquid

    NASA Astrophysics Data System (ADS)

    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.

  7. Single-crystalline octahedral Au-Ag nanoframes.

    PubMed

    Hong, Xun; Wang, Dingsheng; Cai, Shuangfei; Rong, Hongpan; Li, Yadong

    2012-11-01

    We report the formation of single-crystalline octahedral Au-Ag nanoframes by a modified galvanic replacement reaction. Upon sequential addition of AgNO(3), CuCl, and HAuCl(4) to octadecylamine solution, truncated polyhedral silver nanoparticles formed first and then changed into octahedral Au-Ag nanoframes, without requiring a conventional Ag removal step with additional oxidation etchant. The nanoframes have 12 sides, and all of the eight {111} faces are empty. The side grows along the [110] direction, and the diameter is less than 10 nm. The selective gold deposition on the high-energy (110) surface, the diffusion, and the selective redeposition of Au and Ag atoms are the key reasons for the formation of octahedral nanoframes.

  8. Enhancing the reactivity of gold: Nanostructured Au(111) adsorbs CO

    NASA Astrophysics Data System (ADS)

    Hoffmann, F. M.; Hrbek, J.; Ma, S.; Park, J. B.; Rodriguez, J. A.; Stacchiola, D. J.; Senanayake, S. D.

    2016-08-01

    Low-coordinated sites are surface defects whose presence can transform a surface of inert or noble metal such as Au into an active catalyst. Starting with a well-ordered Au(111) surface we prepared by ion sputtering gold surfaces modified by pits, used microscopy (STM) for their structural characterization and CO spectroscopy (IRAS and NEXAFS) for probing reactivity of surface defects. In contrast to the Au(111) surface CO adsorbs readily on the pitted surfaces bonding to low-coordinated sites identified as step atoms forming {111} and {100} microfacets. Pitted nanostructured surfaces can serve as interesting and easily prepared models of catalytic surfaces with defined defects that offer an attractive alternative to vicinal surfaces or nanoparticles commonly employed in catalysis science.

  9. Enhancing the reactivity of gold: Nanostructured Au(111) adsorbs CO

    DOE PAGESBeta

    Hoffmann, F. M.; Hrbek, J.; Ma, S.; Park, J. B.; Rodriguez, J. A.; Stacchiola, D. J.; Senanayake, S. D.

    2015-12-02

    Low-coordinated sites are surface defects whose presence can transform a surface of inert or noble metal such as Au into an active catalyst. We prepared gold surfaces modified by pits, starting with a well-ordered Au(111) surface; we then used microscopy (STM) for their structural characterization and CO spectroscopy (IRAS and NEXAFS) for probing reactivity of surface defects. In contrast to the Au(111) surface CO adsorbs readily on the pitted surfaces bonding to low-coordinated sites identified as step atoms forming {111} and {100} microfacets. Finally, pitted nanostructured surfaces can serve as interesting and easily prepared models of catalytic surfaces with definedmore » defects that offer an attractive alternative to vicinal surfaces or nanoparticles commonly employed in catalysis science.« less

  10. Enhancing the reactivity of gold: Nanostructured Au(111) adsorbs CO

    SciTech Connect

    Hoffmann, F. M.; Hrbek, J.; Ma, S.; Park, J. B.; Rodriguez, J. A.; Stacchiola, D. J.; Senanayake, S. D.

    2015-12-02

    Low-coordinated sites are surface defects whose presence can transform a surface of inert or noble metal such as Au into an active catalyst. We prepared gold surfaces modified by pits, starting with a well-ordered Au(111) surface; we then used microscopy (STM) for their structural characterization and CO spectroscopy (IRAS and NEXAFS) for probing reactivity of surface defects. In contrast to the Au(111) surface CO adsorbs readily on the pitted surfaces bonding to low-coordinated sites identified as step atoms forming {111} and {100} microfacets. Finally, pitted nanostructured surfaces can serve as interesting and easily prepared models of catalytic surfaces with defined defects that offer an attractive alternative to vicinal surfaces or nanoparticles commonly employed in catalysis science.

  11. Nucleation-Suppressed Phase Stabilization in Fe–Au Nanoparticles

    SciTech Connect

    Mukherjee, P.; Jiang, Xiujuan; Wu, Yaqiao; Kramer, Matthew J.; Shield, J. E.

    2013-10-18

    Four nanoparticle compositions, Fe–21, 35, 47, and 67 at. % Au, have been prepared to study the phase stability and solid-state transformation in confined Fe–Au nanoalloys. The formation of two phases, predicted from bulk thermodynamics, has been suppressed in all compositions. Instead, a single phase solid solution forms after heat treatment at 600 °C and slow cooling. However, bulk phase relationships, signified by the precipitation of α-Fe upon cooling, was observed in larger particles (>20 nm) with composition Fe–35 at. % Au. The suppression of the phase transformation/precipitation in small particles is explained thermodynamically, as the free energy decrease associated with the phase transformation does not exceed the increase in energy due to the introduction of an interphase interface (grain boundary) within the cluster. A general equation has been derived to predict the critical cluster size below which transformations are inhibited, which agrees well with the observed experimental results.

  12. Fabrication of Au/Ni Multilayered Nanowires by Electrochemical Deposition

    NASA Astrophysics Data System (ADS)

    Saidin, N. U.; Kok, K. Y.; Ng, I. K.; Ilias, S. H.

    2013-04-01

    Electrochemical deposition of Au/Ni multilayered nanowires using template-assisted growth technique from electrolyte containing nickel chloride and gold solution was studied in details. 60 μm-thick anodized aluminum oxide (AAO) with pore diameter of 200 nm was used as the template. Chronopotentiometry experiments were first carried out to determine the deposition conditions and the growth rate of individual Au and Ni layers. Scanning electron microscopy results revealed that the pore channels of AAO were completely filled with Au/Ni multisegmented nanowires. By selectively removing the Ni segments in the multilayered nanowires, high-yield of pure gold nanorods were obtained. Detailed studies on the nanostructures obtained were carried out using various microscopy and probe-based techniques for structural, morphological and chemical characterizations.

  13. Influence of the S-Au Bond Strength on the Magnetic Behavior of S-Capped Au Nanoparticles

    NASA Astrophysics Data System (ADS)

    Vázquez, María J. Rodríguez; Rivas, José; López-Quintela, M. Arturo; Mosquera, Antonio Mouriño; Torneiro, Mercedes

    Recently, large permanent atomic magnetic moments have been found in Au nanoparticles capped with thiols. It is assumed that the formation of localized Au-S bonds at the particle surface induces the damping of the surface plasmon resonance and the appearance of a ferromagnetic-like behavior. In this work we will show for the first time that thioethers can also induce both phenomena, i.e., the damping of the plasmon band and the appearance of permanent magnetic moments. Furthermore, we have studied the influence of the Au-S bond strength on both phenomena using two different synthesized thioether ligands. It will be shown that, although both ligands can induce a complete damping of the plasmon band, only with one of the ligands (the one corresponding to the stronger S-Au bond) the appearance of a ferromagnetic-like order is observed. This is an indication of the extreme sensitivity of the magnetism on the strength of the charge transfer at the S-Au bond.

  14. Measurement of direct photons in Au+Au collisions at √(s(NN))=200 GeV.

    PubMed

    Afanasiev, S; Aidala, C; Ajitanand, N N; Akiba, Y; Al-Jamel, A; Alexander, J; Aoki, K; Aphecetche, L; Armendariz, R; Aronson, S H; Averbeck, R; Awes, T C; Azmoun, B; Babintsev, V; Baldisseri, A; Barish, K N; Barnes, P D; Bassalleck, B; Bathe, S; Batsouli, S; Baublis, V; Bauer, F; Bazilevsky, A; Belikov, S; Bennett, R; Berdnikov, Y; Bjorndal, M T; Boissevain, J G; Borel, H; Boyle, K; Brooks, M L; Brown, D S; Bucher, D; Buesching, H; Bumazhnov, V; Bunce, G; Burward-Hoy, J M; Butsyk, S; Campbell, S; Chai, J-S; Chernichenko, S; Chi, C Y; Chiba, J; Chiu, M; Choi, I J; Chujo, T; Cianciolo, V; Cleven, C R; Cobigo, Y; Cole, B A; Comets, M P; Connors, M; Constantin, P; Csanád, M; Csörgő, T; Dahms, T; Das, K; David, G; Delagrange, H; Denisov, A; d'Enterria, D; Deshpande, A; Desmond, E J; Dietzsch, O; Dion, A; Drachenberg, J L; Drapier, O; Drees, A; Dubey, A K; Durum, A; Dzhordzhadze, V; Efremenko, Y V; Egdemir, J; Enokizono, A; En'yo, H; Espagnon, B; Esumi, S; Fields, D E; Fleuret, F; Fokin, S L; Forestier, B; Fraenkel, Z; Frantz, J E; Franz, A; Frawley, A D; Fukao, Y; Fung, S-Y; Gadrat, S; Gastineau, F; Germain, M; Glenn, A; Gonin, M; Gosset, J; Goto, Y; Granier de Cassagnac, R; Grau, N; Greene, S V; Grosse Perdekamp, M; Gunji, T; Gustafsson, H-Å; Hachiya, T; Hadj Henni, A; Haggerty, J S; Hagiwara, M N; Hamagaki, H; Harada, H; Hartouni, E P; Haruna, K; Harvey, M; Haslum, E; Hasuko, K; Hayano, R; He, X; Heffner, M; Hemmick, T K; Heuser, J M; Hiejima, H; Hill, J C; Hobbs, R; Holmes, M; Holzmann, W; Homma, K; Hong, B; Horaguchi, T; Hur, M G; Ichihara, T; Iinuma, H; Imai, K; Imrek, J; Inaba, M; Isenhower, D; Isenhower, L; Ishihara, M; Isobe, T; Issah, M; Isupov, A; Jacak, B V; Jia, J; Jin, J; Jinnouchi, O; Johnson, B M; Joo, K S; Jouan, D; Kajihara, F; Kametani, S; Kamihara, N; Kaneta, M; Kang, J H; Kawagishi, T; Kazantsev, A V; Kelly, S; Khanzadeev, A; Kim, D J; Kim, E; Kim, Y-S; Kinney, E; Kiss, A; Kistenev, E; Kiyomichi, A; Klein-Boesing, C; Kochenda, L; Kochetkov, V; Komkov, B; Konno, M; Kotchetkov, D; Kozlov, A; Kroon, P J; Kunde, G J; Kurihara, N; Kurita, K; Kweon, M J; Kwon, Y; Kyle, G S; Lacey, R; Lajoie, J G; Lebedev, A; Le Bornec, Y; Leckey, S; Lee, D M; Lee, M K; Leitch, M J; Leite, M A L; Li, X H; Lim, H; Litvinenko, A; Liu, M X; Maguire, C F; Makdisi, Y I; Malakhov, A; Malik, M D; Manko, V I; Masui, H; Matathias, F; McCain, M C; McGaughey, P L; Miake, Y; Miller, T E; Milov, A; Mioduszewski, S; Mishra, G C; Mitchell, J T; Morrison, D P; Moss, J M; Moukhanova, T V; Mukhopadhyay, D; Murata, J; Nagamiya, S; Nagata, Y; Nagle, J L; Naglis, M; Nakamura, T; Newby, J; Nguyen, M; Norman, B E; Nyanin, A S; Nystrand, J; O'Brien, E; Ogilvie, C A; Ohnishi, H; Ojha, I D; Okada, K; Omiwade, O O; Oskarsson, A; Otterlund, I; Ozawa, K; Pak, R; Pal, D; Palounek, A P T; Pantuev, V; Papavassiliou, V; Park, J; Park, W J; Pate, S F; Pei, H; Peng, J-C; Pereira, H; Peresedov, V; Peressounko, D Yu; Pinkenburg, C; Pisani, R P; Purschke, M L; Purwar, A K; Qu, H; Rak, J; Ravinovich, I; Read, K F; Reuter, M; Reygers, K; Riabov, V; Riabov, Y; Roche, G; Romana, A; Rosati, M; Rosendahl, S S E; Rosnet, P; Rukoyatkin, P; Rykov, V L; Ryu, S S; Sahlmueller, B; Saito, N; Sakaguchi, T; Sakai, S; Samsonov, V; Sato, H D; Sato, S; Sawada, S; Semenov, V; Seto, R; Sharma, D; Shea, T K; Shein, I; Shibata, T-A; Shigaki, K; Shimomura, M; Shohjoh, T; Shoji, K; Sickles, A; Silva, C L; Silvermyr, D; Sim, K S; Singh, C P; Singh, V; Skutnik, S; Smith, W C; Soldatov, A; Soltz, R A; Sondheim, W E; Sorensen, S P; Sourikova, I V; Staley, F; Stankus, P W; Stenlund, E; Stepanov, M; Ster, A; Stoll, S P; Sugitate, T; Suire, C; Sullivan, J P; Sziklai, J; Tabaru, T; Takagi, S; Takagui, E M; Taketani, A; Tanaka, K H; Tanaka, Y; Tanida, K; Tannenbaum, M J; Taranenko, A; Tarján, P; Thomas, T L; Togawa, M; Tojo, J; Torii, H; Towell, R S; Tram, V-N; Tserruya, I; Tsuchimoto, Y; Tuli, S K; Tydesjö, H; Tyurin, N; Vale, C; Valle, H; van Hecke, H W; Velkovska, J; Vértesi, R; Vinogradov, A A; Vznuzdaev, E; Wagner, M; Wang, X R; Watanabe, Y; Wessels, J; White, S N; Willis, N; Winter, D; Woody, C L; Wysocki, M; Xie, W; Yanovich, A; Yokkaichi, S; Young, G R; Younus, I; Yushmanov, I E; Zajc, W A; Zaudtke, O; Zhang, C; Zimányi, J; Zolin, L

    2012-10-12

    We report the measurement of direct photons at midrapidity in Au+Au collisions at √(s(NN))=200 GeV. The direct photon signal was extracted for the transverse momentum range of 4 GeV/cAu+Au collision centralities using the measured p+p direct photon spectrum and compared to theoretical predictions. R(AA) was found to be consistent with unity for all centralities over the entire measured p(T) range. Theoretical models that account for modifications of initial direct photon production due to modified parton distribution functions in Au and the different isospin composition of the nuclei predict a modest change of R(AA) from unity. They are consistent with the data. Models with compensating effects of the quark-gluon plasma on high-energy photons, such as suppression of jet-fragmentation photons and induced-photon bremsstrahlung from partons traversing the medium, are also consistent with this measurement. PMID:23102300

  15. Nonideality of Au/Si and Au/GaAs Schottky barriers due to process-induced defects

    NASA Astrophysics Data System (ADS)

    Maeda, Keiji

    2006-06-01

    A mechanism of local lowering of the Schottky barrier height (SBH) is proposed, which causes nonideality in nearly ideal Au/ n-Si and Au/ n-GaAs Schottky barriers. Positively ionized defects generated by the process very close to the interface induce electrons in the metal-induced gap states (MIGS) and lower the SBH locally. The spatial density distribution of the ionized defects obtained from the SBH distribution is determined by the unique interaction with the MIGS. The defects are considered to have the negative-U property and are neutralized at very close positions to the MIGS. The potential distributions close to the interface have a considerable potential drop due to the large defect density. These inhomogeneous potentials are coincident with the energy level scheme of the defect identified as the defect causing the nonideality. This defect is Si self-interstitial in Au/Si SB, and As antisite in Au/ n-GaAs SB. This MIGS with process-induced defect model supersedes the previously proposed two major Fermi level pinning models. The mystery of the T0 effect is solved. The thermionic-field emission current taking place in the strong electric field has influence on the I- V characteristics at low temperatures. Regarding the C- V characteristics of Au/Si SB, the observed extra capacitance under the forward bias is an experimental evidence in accordance with the proposed model.

  16. Measurement of direct photons in Au+Au collisions at √(s(NN))=200 GeV.

    PubMed

    Afanasiev, S; Aidala, C; Ajitanand, N N; Akiba, Y; Al-Jamel, A; Alexander, J; Aoki, K; Aphecetche, L; Armendariz, R; Aronson, S H; Averbeck, R; Awes, T C; Azmoun, B; Babintsev, V; Baldisseri, A; Barish, K N; Barnes, P D; Bassalleck, B; Bathe, S; Batsouli, S; Baublis, V; Bauer, F; Bazilevsky, A; Belikov, S; Bennett, R; Berdnikov, Y; Bjorndal, M T; Boissevain, J G; Borel, H; Boyle, K; Brooks, M L; Brown, D S; Bucher, D; Buesching, H; Bumazhnov, V; Bunce, G; Burward-Hoy, J M; Butsyk, S; Campbell, S; Chai, J-S; Chernichenko, S; Chi, C Y; Chiba, J; Chiu, M; Choi, I J; Chujo, T; Cianciolo, V; Cleven, C R; Cobigo, Y; Cole, B A; Comets, M P; Connors, M; Constantin, P; Csanád, M; Csörgő, T; Dahms, T; Das, K; David, G; Delagrange, H; Denisov, A; d'Enterria, D; Deshpande, A; Desmond, E J; Dietzsch, O; Dion, A; Drachenberg, J L; Drapier, O; Drees, A; Dubey, A K; Durum, A; Dzhordzhadze, V; Efremenko, Y V; Egdemir, J; Enokizono, A; En'yo, H; Espagnon, B; Esumi, S; Fields, D E; Fleuret, F; Fokin, S L; Forestier, B; Fraenkel, Z; Frantz, J E; Franz, A; Frawley, A D; Fukao, Y; Fung, S-Y; Gadrat, S; Gastineau, F; Germain, M; Glenn, A; Gonin, M; Gosset, J; Goto, Y; Granier de Cassagnac, R; Grau, N; Greene, S V; Grosse Perdekamp, M; Gunji, T; Gustafsson, H-Å; Hachiya, T; Hadj Henni, A; Haggerty, J S; Hagiwara, M N; Hamagaki, H; Harada, H; Hartouni, E P; Haruna, K; Harvey, M; Haslum, E; Hasuko, K; Hayano, R; He, X; Heffner, M; Hemmick, T K; Heuser, J M; Hiejima, H; Hill, J C; Hobbs, R; Holmes, M; Holzmann, W; Homma, K; Hong, B; Horaguchi, T; Hur, M G; Ichihara, T; Iinuma, H; Imai, K; Imrek, J; Inaba, M; Isenhower, D; Isenhower, L; Ishihara, M; Isobe, T; Issah, M; Isupov, A; Jacak, B V; Jia, J; Jin, J; Jinnouchi, O; Johnson, B M; Joo, K S; Jouan, D; Kajihara, F; Kametani, S; Kamihara, N; Kaneta, M; Kang, J H; Kawagishi, T; Kazantsev, A V; Kelly, S; Khanzadeev, A; Kim, D J; Kim, E; Kim, Y-S; Kinney, E; Kiss, A; Kistenev, E; Kiyomichi, A; Klein-Boesing, C; Kochenda, L; Kochetkov, V; Komkov, B; Konno, M; Kotchetkov, D; Kozlov, A; Kroon, P J; Kunde, G J; Kurihara, N; Kurita, K; Kweon, M J; Kwon, Y; Kyle, G S; Lacey, R; Lajoie, J G; Lebedev, A; Le Bornec, Y; Leckey, S; Lee, D M; Lee, M K; Leitch, M J; Leite, M A L; Li, X H; Lim, H; Litvinenko, A; Liu, M X; Maguire, C F; Makdisi, Y I; Malakhov, A; Malik, M D; Manko, V I; Masui, H; Matathias, F; McCain, M C; McGaughey, P L; Miake, Y; Miller, T E; Milov, A; Mioduszewski, S; Mishra, G C; Mitchell, J T; Morrison, D P; Moss, J M; Moukhanova, T V; Mukhopadhyay, D; Murata, J; Nagamiya, S; Nagata, Y; Nagle, J L; Naglis, M; Nakamura, T; Newby, J; Nguyen, M; Norman, B E; Nyanin, A S; Nystrand, J; O'Brien, E; Ogilvie, C A; Ohnishi, H; Ojha, I D; Okada, K; Omiwade, O O; Oskarsson, A; Otterlund, I; Ozawa, K; Pak, R; Pal, D; Palounek, A P T; Pantuev, V; Papavassiliou, V; Park, J; Park, W J; Pate, S F; Pei, H; Peng, J-C; Pereira, H; Peresedov, V; Peressounko, D Yu; Pinkenburg, C; Pisani, R P; Purschke, M L; Purwar, A K; Qu, H; Rak, J; Ravinovich, I; Read, K F; Reuter, M; Reygers, K; Riabov, V; Riabov, Y; Roche, G; Romana, A; Rosati, M; Rosendahl, S S E; Rosnet, P; Rukoyatkin, P; Rykov, V L; Ryu, S S; Sahlmueller, B; Saito, N; Sakaguchi, T; Sakai, S; Samsonov, V; Sato, H D; Sato, S; Sawada, S; Semenov, V; Seto, R; Sharma, D; Shea, T K; Shein, I; Shibata, T-A; Shigaki, K; Shimomura, M; Shohjoh, T; Shoji, K; Sickles, A; Silva, C L; Silvermyr, D; Sim, K S; Singh, C P; Singh, V; Skutnik, S; Smith, W C; Soldatov, A; Soltz, R A; Sondheim, W E; Sorensen, S P; Sourikova, I V; Staley, F; Stankus, P W; Stenlund, E; Stepanov, M; Ster, A; Stoll, S P; Sugitate, T; Suire, C; Sullivan, J P; Sziklai, J; Tabaru, T; Takagi, S; Takagui, E M; Taketani, A; Tanaka, K H; Tanaka, Y; Tanida, K; Tannenbaum, M J; Taranenko, A; Tarján, P; Thomas, T L; Togawa, M; Tojo, J; Torii, H; Towell, R S; Tram, V-N; Tserruya, I; Tsuchimoto, Y; Tuli, S K; Tydesjö, H; Tyurin, N; Vale, C; Valle, H; van Hecke, H W; Velkovska, J; Vértesi, R; Vinogradov, A A; Vznuzdaev, E; Wagner, M; Wang, X R; Watanabe, Y; Wessels, J; White, S N; Willis, N; Winter, D; Woody, C L; Wysocki, M; Xie, W; Yanovich, A; Yokkaichi, S; Young, G R; Younus, I; Yushmanov, I E; Zajc, W A; Zaudtke, O; Zhang, C; Zimányi, J; Zolin, L

    2012-10-12

    We report the measurement of direct photons at midrapidity in Au+Au collisions at √(s(NN))=200 GeV. The direct photon signal was extracted for the transverse momentum range of 4 GeV/cAu+Au collision centralities using the measured p+p direct photon spectrum and compared to theoretical predictions. R(AA) was found to be consistent with unity for all centralities over the entire measured p(T) range. Theoretical models that account for modifications of initial direct photon production due to modified parton distribution functions in Au and the different isospin composition of the nuclei predict a modest change of R(AA) from unity. They are consistent with the data. Models with compensating effects of the quark-gluon plasma on high-energy photons, such as suppression of jet-fragmentation photons and induced-photon bremsstrahlung from partons traversing the medium, are also consistent with this measurement.

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

    SciTech Connect

    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.

  18. Formation of one-dimensional Ag-Au solid solution colloids with Au nanorods as seeds, their alloying mechanisms, and surface plasmon resonances.

    PubMed

    Guo, Tao; Tan, Yiwei

    2013-01-21

    In this work, one dimensional (1D) Ag-Au solid solution nanoalloys were synthesized by rapidly diffusing Ag into the preformed Au nanorod (AuNR) seeds at ambient temperature in aqueous solution. By varying the molar ratio of AgCl/AuNR (in gold atoms), two kinds of 1D Ag-Au alloy nanostructures with a narrow size distribution--AgAu nanowires and Ag(33)Au(67) nanorods--could be obtained in high yields when NaCl and polyvinylpyrrolidone (PVP) were used as an additive and capping reagent, respectively. Based on HRTEM imaging combined with a series of control experiments, it is conceivable that vacancy/defect-motivated interdiffusion of Ag and Au atoms coupled with oxidative etching is a crucial stage in the mechanism responsible for this room-temperature alloying process, and the subsequent conjugation of the fused Ag-Au alloyed nanostructures is associated with the formation of the AgAu nanowires. The resulting 1D Ag-Au nanoalloys form stable colloidal dispersions and show unique localized surface plasmon resonance (LSPR) peaks in the ensemble extinction spectra.

  19. Common suppression pattern of eta and pi0 mesons at high transverse momentum in Au + Au collisions at square root S(NN) = 200 GeV.

    PubMed

    Adler, S S; Afanasiev, S; Aidala, C; Ajitanand, N N; Akiba, Y; Alexander, J; Amirikas, R; Aphecetche, L; Aronson, S H; Averbeck, R; Awes, T C; Azmoun, R; Babintsev, V; Baldisseri, A; Barish, K N; Barnes, P D; Bassalleck, B; Bathe, S; Batsouli, S; Baublis, V; Bazilevsky, A; Belikov, S; Berdnikov, Y; Bhagavatula, S; Boissevain, J G; Borel, H; Borenstein, S; Brooks, M L; Brown, D S; Bruner, N; Bucher, D; Buesching, H; Bumazhnov, V; Bunce, G; Burward-Hoy, J M; Butsyk, S; Camard, X; Chai, J-S; Chand, P; Chang, W C; Chernichenko, S; Chi, C Y; Chiba, J; Chiu, M; Choi, I J; Choi, J; Choudhury, R K; Chujo, T; Cianciolo, V; Cobigo, Y; Cole, B A; Constantin, P; d'Enterria, D; David, G; Delagrange, H; Denisov, A; Deshpande, A; Desmond, E J; Devismes, A; Dietzsch, O; Drapier, O; Drees, A; du Rietz, R; Durum, A; Dutta, D; Efremenko, Y V; Chenawi, K El; Enokizono, A; En'yo, H; Esumi, S; Ewell, L; Fields, D E; Fleuret, F; Fokin, S L; Fox, B D; Fraenkel, Z; Frantz, J E; Franz, A; Frawley, A D; Fung, S-Y; Garpman, S; Ghosh, T K; Glenn, A; Gogiberidze, G; Gonin, M; Gosset, J; Goto, Y; de Cassagnac, R Granier; Grau, N; Greene, S V; Perdekamp, M Grosse; Guryn, W; Gustafsson, H-A; Hachiya, T; Haggerty, J S; Hamagaki, H; Hansen, A G; Hartouni, E P; Harvey, M; Hayano, R; Hayashi, N; He, X; Heffner, M; Hemmick, T K; Heuser, J M; Hibino, M; Hiejima, H; Hill, J C; Holzmann, W; Homma, K; Hong, B; Hoover, A; Ichihara, T; Ikonnikov, V V; Imai, K; Isenhower, D; Ishihara, M; Issah, M; Isupov, A; Jacak, B V; Jang, W Y; Jeong, Y; Jia, J; Jinnouchi, O; Johnson, B M; Johnson, S C; Joo, K S; Jouan, D; Kametani, S; Kamihara, N; Kang, J H; Kapoor, S S; Katou, K; Kelly, S; Khachaturov, B; Khanzadeev, A; Kikuchi, J; Kim, D H; Kim, D J; Kim, D W; Kim, E; Kim, G-B; Kim, H J; Kistenev, E; Kiyomichi, A; Kiyoyama, K; Klein-Boesing, C; Kobayashi, H; Kochenda, L; Kochetkov, V; Koehler, D; Kohama, T; Kopytine, M; Kotchetkov, D; Kozlov, A; Kroon, P J; Kuberg, C H; Kurita, K; Kuroki, Y; Kweon, M J; Kwon, Y; Kyle, G S; Lacey, R; Ladygin, V; Lajoie, J G; Lebedev, A; Leckey, S; Lee, D M; Lee, S; Leitch, M J; Li, X H; Lim, H; Litvinenko, A; Liu, M X; Liu, Y; Maguire, C F; Makdisi, Y I; Malakhov, A; Manko, V I; Mao, Y; Martinez, G; Marx, M D; Masui, H; Matathias, F; Matsumoto, T; McGaughey, P L; Melnikov, E; Messer, F; Miake, Y; Milan, J; Miller, T E; Milov, A; Mioduszewski, S; Mischke, R E; Mishra, G C; Mitchell, J T; Mohanty, A K; Morrison, D P; Moss, J M; Mühlbacher, F; Mukhopadhyay, D; Muniruzzaman, M; Murata, J; Nagamiya, S; Nagle, J L; Nakamura, T; Nandi, B K; Nara, M; Newby, J; Nilsson, P; Nyanin, A S; Nystrand, J; O'Brien, E; Ogilvie, C A; Ohnishi, H; Ojha, I D; Okada, K; Ono, M; Onuchin, V; Oskarsson, A; Otterlund, I; Oyama, K; Ozawa, K; Pal, D; Palounek, A P T; Pantuev, V; Papavassiliou, V; Park, J; Parmar, A; Pate, S F; Peitzmann, T; Peng, J-C; Peresedov, V; Pinkenburg, C; Pisani, R P; Plasil, F; Purschke, M L; Purwar, A K; Rak, J; Ravinovich, I; Read, K F; Reuter, M; Reygers, K; Riabov, V; Riabov, Y; Roche, G; Romana, A; Rosati, M; Rosnet, P; Ryu, S S; Sadler, M E; Sahlmueller, B; Saito, N; Sakaguchi, T; Sakai, M; Sakai, S; Samsonov, V; Sanfratello, L; Santo, R; Sato, H D; Sato, S; Sawada, S; Schutz, Y; Semenov, V; Seto, R; Shaw, M R; Shea, T K; Shibata, T-A; Shigaki, K; Shiina, T; Silva, C L; Silvermyr, D; Sim, K S; Singh, C P; Singh, V; Sivertz, M; Soldatov, A; Soltz, R A; Sondheim, W E; Sorensen, S P; Sourikova, I V; Staley, F; Stankus, P W; Stenlund, E; Stepanov, M; Ster, A; Stoll, S P; Sugitate, T; Sullivan, J P; Takagui, E M; Taketani, A; Tamai, M; Tanaka, K H; Tanaka, Y; Tanida, K; Tannenbaum, M J; Tarján, P; Tepe, J D; Thomas, T L; Tojo, J; Torii, H; Towell, R S; Tserruya, I; Tsuruoka, H; Tuli, S K; Tydesjö, H; Tyurin, N; van Hecke, H W; Velkovska, J; Velkovsky, M; Veszprémi, V; Villatte, L; Vinogradov, A A; Volkov, M A; Vznuzdaev, E; Wang, X R; Watanabe, Y; White, S N; Wohn, F K; Woody, C L; Xie, W; Yang, Y; Yanovich, A; Yokkaichi, S; Young, G R; Yushmanov, I E; Zajc, W A; Zhang, C; Zhou, S; Zhou, S J; Zolin, L

    2006-05-26

    Inclusive transverse momentum spectra of eta mesons have been measured within p(T) = 2-10 GeV/c at midrapidity by the PHENIX experiment in Au + Au collisions at square root S(NN) = 200 GeV. In central Au+Au the eta yields are significantly suppressed compared to peripheral Au + Au, d + Au, and p + p yields scaled by the corresponding number of nucleon-nucleon collisions. The magnitude, centrality, and p(T) dependence of the suppression is common, within errors, for eta and pi0. The ratio of eta to pi0 spectra at high p(T) amounts to 0.40 < R(eta/pi)0 < 0.48 for the three systems, in agreement with the world average measured in hadronic and nuclear reactions and, at large scaled momentum, in e+e- collisions.

  20. Using bond-length-dependent transferable force constants to predict vibrational entropies in Au-Cu, Au-Pd, and Cu-Pd alloys

    NASA Astrophysics Data System (ADS)

    Wu, Eric J.; Ceder, Gerbrand; van de Walle, Axel

    2003-04-01

    A model is tested to rapidly evaluate the vibrational properties of alloys with site disorder. It is shown that length-dependent transferable force constants exist and can be used to accurately predict the vibrational entropy of substitutionally ordered and disordered structures in Au-Cu, Au-Pd, and Cu-Pd. For each relevant force constant, a length-dependent function is determined and fitted to force constants obtained from first-principles pseudopotential calculations. We show that these transferable force constants can accurately predict vibrational entropies of L12-ordered and disordered phases in Cu3Au, Au3Pd, Pd3Au, Cu3Pd, and Pd3Au. In addition, we calculate the vibrational entropy difference between L12-ordered and disordered phases of Au3Cu and Cu3Pt.

  1. The coupled geochemistry of Au and As in pyrite from hydrothermal ore deposits

    NASA Astrophysics Data System (ADS)

    Deditius, Artur P.; Reich, Martin; Kesler, Stephen E.; Utsunomiya, Satoshi; Chryssoulis, Stephen L.; Walshe, John; Ewing, Rodney C.

    2014-09-01

    The ubiquity of Au-bearing arsenian pyrite in hydrothermal ore deposits suggests that the coupled geochemical behaviour of Au and As in this sulfide occurs under a wide range of physico-chemical conditions. Despite significant advances in the last 20 years, fundamental factors controlling Au and As ratios in pyrite from ore deposits remain poorly known. Here we explore these constraints using new and previously published EMPA, LA-ICP-MS, SIMS, and μ-PIXE analyses of As and Au in pyrite from Carlin-type Au, epithermal Au, porphyry Cu, Cu-Au, and orogenic Au deposits, volcanogenic massive sulfide (VHMS), Witwatersrand Au, iron oxide copper gold (IOCG), and coal deposits. Pyrite included in the data compilation formed under temperatures from ∼30 to ∼600 °C and in a wide variety of geological environments. The pyrite Au-As data form a wedge-shaped zone in compositional space, and the fact that most data points plot below the solid solubility limit defined by Reich et al. (2005) indicate that Au1+ is the dominant form of Au in arsenian pyrite and that Au-bearing ore fluids that deposit this sulfide are mostly undersaturated with respect to native Au. The analytical data also show that the solid solubility limit of Au in arsenian pyrite defined by an Au/As ratio of 0.02 is independent of the geochemical environment of pyrite formation and rather depends on the crystal-chemical properties of pyrite and post-depositional alteration. Compilation of Au-As concentrations and formation temperatures for pyrite indicates that Au and As solubility in pyrite is retrograde; Au and As contents decrease as a function of increasing temperature from ∼200 to ∼500 °C. Based on these results, two major Au-As trends for Au-bearing arsenian pyrite from ore deposits are defined. One trend is formed by pyrites from Carlin-type and orogenic Au deposits where compositions are largely controlled by fluid-rock interactions and/or can be highly perturbed by changes in temperature and

  2. Reduced graphene oxide supported Au nanoparticles as an efficient catalyst for aerobic oxidation of benzyl alcohol

    NASA Astrophysics Data System (ADS)

    Yu, Xianqin; Huo, Yujia; Yang, Jing; Chang, Sujie; Ma, Yunsheng; Huang, Weixin

    2013-09-01

    Various Au/C catalysts were prepared by Au nanoparticels supported on different carbonaceous supports including reduced graphene oxide (RGO), activated carbon (AC) and graphite (GC) using sol-immobilization method. Au/RGO shows a much higher activity than Au/AC and Au/GC in the liquid phase aerobic oxidation of benzyl alcohol. The superior catalytic performance of Au/RGO may be related to the presence of surface O-containing functional groups and moderate graphite character of RGO supports.

  3. Hexagonal-diamond-like gold lattices, Ba and (Au,T)3 interstitials, and delocalized bonding in a family of intermetallic phases Ba2Au6(Au,T)3 (T = Zn, Cd, Ga, In, or Sn).

    PubMed

    Lin, Qisheng; Mishra, Trinath; Corbett, John D

    2013-07-31

    Au-rich polar intermetallics exhibit a wide variety of structural motifs, and this hexagonal-diamond-like gold host is unprecedented. The series Ba2Au6(Au,T)3 (T = Zn, Cd, Ga, In, or Sn), synthesized through fusion of the elements at 700-800 °C followed by annealing at 400-500 °C, occur in space group R3[overline]c (a ≈ 8.6-8.9 Å, c ≈ 21.9-22.6 Å, and Z = 6). Their remarkable structure, generated by just three independent atoms, features a hexagonal-diamond-like gold superstructure in which tunnels along the 3-fold axes are systematically filled by interstitial Ba atoms (blue) and triangles of disordered (Au,T)3 atoms (green) in 2:1 proportions. The Au/Zn mixing in the latter spans ~34 to 87% Zn, whereas the Au/Sn result is virtually invariant compositionally. Complementary bonding between the gold lattice and the disordered (Au,T)3 units is substantial and very regular. Bonding and charge density analyses indicate delocalized bonding within the gold host and the (Au,T)3 triangular units, and moderately polarized bonding between Ba and the electronegative framework. The new structure can also be viewed empirically as the result of an atom-by-triad [i.e., Ba by (Au,T)3 triangle] topological substitution in a BaAu2 (AlB2-type) superstructure.

  4. Collisional modelling of the AU Microscopii debris disc

    NASA Astrophysics Data System (ADS)

    Schüppler, Ch.; Löhne, T.; Krivov, A. V.; Ertel, S.; Marshall, J. P.; Wolf, S.; Wyatt, M. C.; Augereau, J.-C.; Metchev, S. A.

    2015-09-01

    AU Microscopii's debris disc is one of the most famous and best-studied debris discs and one of only two resolved debris discs around M stars. We perform in-depth collisional modelling of the AU Mic disc including stellar radiative and corpuscular forces (stellar winds), aiming at a comprehensive understanding of the dust production and the dust and planetesimal dynamics in the system. Our models are compared to a suite of observational data for thermal and scattered light emission, ranging from the ALMA radial surface brightness profile at 1.3 mm to spatially resolved polarisation measurements in the visible. Most of the data are shown to be reproduced with dust production in a belt of planetesimals with an outer edge at around 40 au and subsequent inward transport of dust by stellar winds. A low dynamical excitation of the planetesimals with eccentricities up to 0.03 is preferred. The radial width of the planetesimal belt cannot be constrained tightly. Belts that are 5 au and 17 au wide, as well as a broad 44 au-wide belt, are consistent with observations. All models show surface density profiles that increase with distance from the star up to ≈40 au, as inferred from observations. The best model is achieved by assuming a stellar mass loss rate that exceeds the solar one by a factor of 50. The models reproduce the spectral energy distribution and the shape of the ALMA radial profile well, but deviate from the scattered light observations more strongly. The observations show a bluer disc colour and a lower degree of polarisation for projected distances <40 au than predicted by the models. These deviations may be reduced by taking irregularly shaped dust grains which have scattering properties different from the Mie spheres used in this work. From tests with a handful of selected dust materials, we favour mixtures of silicate, carbon, and ice of moderate porosity. We also address the origin of the unresolved central excess emission detected by ALMA and show that

  5. Photocatalytic Au-Bi2S3 heteronanostructures.

    PubMed

    Manna, Goutam; Bose, Riya; Pradhan, Narayan

    2014-06-23

    Au-Bi2S3 heteronanostructure photocatalysts were designed in which the coupling of a metal plasmon and a semiconductor exciton aids the absorption of solar light, enhances charge separation, and results in improved catalytic activity. Furthermore, these nanostructures show a unique pattern of structural combination, with Au nanoparticles positioned at the center of Bi2S3 nanorods. The chemistry of formation of these nanostructures, their epitaxy at the junction, and their photoconductance were studied, as well as their photoresponse properties. PMID:24844409

  6. Light nuclei production in relativistic Au+nucleus collisions

    SciTech Connect

    Bennett, M. J.; Pope, J. K.; Beavis, D.; Carroll, J. B.; Chiba, J.; Chikanian, A.; Crawford, H. J.; Cronqvist, M.; Dardenne, Y.; Kumar, B. S.; Nagle, J. L.; Debbe, R.; Doke, T.; Engelage, J.; Greiner, L.; Hayano, R S; Hallman, Timothy J.; Heckman, H. H.; Kashiwagi, T.; Kikuchi, J.; Tanaka, K. H.; Kumar, B. S.; Kuo, C.; Lindstrom, P. J.; Mitchell, J. W.; Nagle, J. L.; Stankus, P.; Tanaka, K. H.; Welsh, R. C.; Zhan, W.

    1998-08-01

    We have measured the yields of protons and A=2-4 nuclei in collisions between 10.8 A GeV/ c Au beams and targets of Al, Cu, and Au. The data, which cover a broad rapidity range at low transverse momenta, were measured as a function of collision centrality using a focusing beam line spectrometer and a high-rate centrality detector. We investigate the dependence of coalescence parameters on event geometry. The data are compared with the predictions of an RQMD+coalescence model. {copyright} {ital 1998} {ital The American Physical Society}

  7. Nanoshells made easy: improving Au layer growth on nanoparticle surfaces.

    PubMed

    Brinson, Bruce E; Lassiter, J Britt; Levin, Carly S; Bardhan, Rizia; Mirin, Nikolay; Halas, Naomi J

    2008-12-16

    The growth of a continuous, uniform Au layer on a dielectric nanoparticle is the critical step in the synthesis of nanoparticles such as nanoshells or nanorice, giving rise to their unique geometry-dependent plasmon resonant properties. Here, we report a novel, streamlined method for Au layer metallization on prepared nanoparticle surfaces using carbon monoxide as the reducing agent. This approach consistently yields plasmonic nanoparticles with highly regular shell layers and is immune to variations in precursor or reagent preparation. Single particle spectroscopy combined with scanning electron microscopy reveal that thinner, more uniform shell layers with correspondingly red-shifted optical resonances are achievable with this approach. PMID:19360963

  8. Effect of tautomerism on Au-6-mercaptopurine nanocluster stability

    NASA Astrophysics Data System (ADS)

    Rashidpour, Neda; Kashid, Vikas; Shah, Vaishali

    2013-02-01

    We have investigated the stability of conjugated nanoparticles of Au-6-Mercaptopurine (6-MP) using ab initio density functional theory. We have studied the conjugation of the 6 tautomers of 6-MP via the different atomic sites with the gold nanoparticles. Our results show that the least stable tautomer has the strongest adsorption with the Au nanoparticles whereas the most stable tautomer has the weakest adsorption. We will discuss our results to explain the experimentally observed increased plasma half life time of the conjugated drug in vitro.

  9. Beyond 3 AU from the Sun: "Hypervolatiles" in Distant Comets

    NASA Astrophysics Data System (ADS)

    Bonev, Boncho P.; Villanueva, Geronimo Luis; Mumma, Michael J.; DiSanti, Michael A.; Paganini, Lucas; Boehnhardt, Hermann; Lippi, Manuela; Gibb, Erika L.; Bockelee-Morvan, Dominique; de Val-Borro, Miguel; Kawakita, Hideyo; Altwegg, Kathrin

    2016-10-01

    Our understanding of inner coma composition in comets has long been biased towards heliocentric distances (Rh) smaller than 2-3 AU. However, observations far from the Sun are also of high value for better understanding the nucleus structure and outgassing of volatiles. Substantial and very important evidence for the activity of distant comets has been accumulated from photometry and analyses of light curves, but direct detections of primary (parent) volatiles are still rare. For example, comet C/2006 W3 (Christensen) remained outside 3.1 AU throughout its apparition, yet it presented the best opportunity since Hale-Bopp (1997) for detailed spectroscopic studies in a distant comet. C/2006 W3 was observed from several space- and ground-based facilities using both infrared and radio techniques. CO, CH4, and C2H6 were measured via infrared spectroscopy at ESO-VLT at Rh = 3.25 AU. Production rates were found to exceed those measured for each of these species in most other comets, despite those comets being observed much closer to the Sun. With its relatively high CO/CO2 ratio, C/2006 W3 also appears as an outlier in the AKARI comet survey of 18 comets. The detections of H2O (Herschel Space Observatory) and CO (ESO-VLT) allow for constraining the coma abundance ratio H2O/CO at Rh = 5 AU.We will compare the C2H6/CH4/CO ratios in C/2006 W3 with those in other comets spanning a large range in Rh: from D/2012 S1 ISON (~0.7 AU) to 29P/Schwassmann-Wachmann 1 (~ 6.3 AU). Notably in situ measurements by the Rosetta mission were performed in the coma of 67P/Churyumov-Gerasimenko, at a very similar heliocentric distance to C/2006 W3 (3.15 AU). While comparisons of column-integrated remote sensing measurements and abundances from in-situ mass spectrometry (as performed by the ROSINA instrument) are not straightforward, both types of measurement are of high value for constraining models of nucleus outgassing beyond 3 AU from the Sun, where the inferred nucleus structure and

  10. Rational design and synthesis of excavated trioctahedral Au nanocrystals

    NASA Astrophysics Data System (ADS)

    Chen, Qiaoli; Jia, Yanyan; Shen, Wei; Xie, Shuifen; Yang, Yanan; Cao, Zhenming; Xie, Zhaoxiong; Zheng, Lansun

    2015-06-01

    Excavated polyhedral nanostructures, possessing the features of high surface area and well-defined surface structure with a specific crystal facet and avoidance of aggregation, could be one of the best choices for the purpose of reducing consumption and improving performance of noble metals in many application fields. However, the formation of the excavated structures is thermodynamically unfavourable and its rational synthesis is far beyond our knowledge. In this work, taking overgrowth of Pd onto trioctahedral Au nanocrystals as a model, we present a deep insight study for synthesizing an excavated structure relying on the protection role of surfactants under suitable crystal growth kinetics. Based on the abovementioned understanding, we designed a simple and effective strategy to synthesize Au nanocrystals with excavated trioctahedral structure in one step. Due to the novel feature of the excavated structure and exposed high energy {110} facets, excavated trioctahedral Au NCs exhibited optical extinction at the near-infrared region and showed high catalytic activity towards the reduction of p-nitrophenol. Moreover, the synthetic strategy can be extended to the synthesis of excavated Au-Pd alloys.Excavated polyhedral nanostructures, possessing the features of high surface area and well-defined surface structure with a specific crystal facet and avoidance of aggregation, could be one of the best choices for the purpose of reducing consumption and improving performance of noble metals in many application fields. However, the formation of the excavated structures is thermodynamically unfavourable and its rational synthesis is far beyond our knowledge. In this work, taking overgrowth of Pd onto trioctahedral Au nanocrystals as a model, we present a deep insight study for synthesizing an excavated structure relying on the protection role of surfactants under suitable crystal growth kinetics. Based on the abovementioned understanding, we designed a simple and effective

  11. Atomic Structure of Au 329 (SR) 84 Faradaurate Plasmonic Nanomolecules

    SciTech Connect

    Kumara, Chanaka; Zuo, Xiaobing; Ilavsky, Jan; Cullen, David A.; Dass, Amala

    2015-05-21

    To design novel nanomaterials, it is important to precisely control the composition, determine the atomic structure, and manipulate the structure to tune the materials property. Here we present a comprehensive characterization of the material whose composition is Au329(SR)84 precisely, therefore referred to as a nanomolecule. The size homogeneity was shown by electron microscopy, solution X-ray scattering, and mass spectrometry. We proposed its atomic structure to contain the Au260 core using experiments and modeling of a total-scattering-based atomic-pair distribution functional analysis. HAADF- STEM images shows fcc-like 2.0 ± 0.1 nm diameter nanomolecules.

  12. Atomic Structure of Au329(SR)84 Faradaurate Plasmonic Nanomolecules

    DOE PAGESBeta

    Kumara, Chanaka; Zuo, Xiaobing; Ilavsky, Jan; Cullen, David; Dass, Amala

    2015-04-03

    To design novel nanomaterials, it is important to precisely control the composition, determine the atomic structure, and manipulate the structure to tune the materials property. Here we present a comprehensive characterization of the material whose composition is Au329(SR)84 precisely, therefore referred to as a nanomolecule. The size homogeneity was shown by electron microscopy, solution X-ray scattering, and mass spectrometry. We proposed its atomic structure to contain the Au260 core using experiments and modeling of a total-scattering-based atomic-pair distribution functional analysis. HAADF-STEM images shows fcc-like 2.0 ± 0.1 nm diameter nanomolecules.

  13. Self-assembly of flagellin on Au(111) surfaces.

    PubMed

    González Orive, Alejandro; Pissinis, Diego E; Diaz, Carolina; Miñán, Alejandro; Benítez, Guillermo A; Rubert, Aldo; Daza Millone, Antonieta; Rumbo, Martin; Hernández Creus, Alberto; Salvarezza, Roberto C; Schilardi, Patricia L

    2014-11-01

    The adsorption of flagellin monomers from Pseudomonas fluorescens on Au(111) has been studied by Atomic Force Microscopy (AFM), Scanning Tunneling Microscopy (STM), X-ray Photoelectron Spectroscopy (XPS), Surface Plasmon Resonance (SPR), and electrochemical techniques. Results show that flagellin monomers spontaneously self-assemble forming a monolayer thick protein film bounded to the Au surface by the more hydrophobic subunit and exposed to the environment the hydrophilic subunit. The films are conductive and allow allocation of electrochemically active cytochrome C. The self-assembled films could be used as biological platforms to build 3D complex molecular structures on planar metal surfaces and to functionalize metal nanoparticles.

  14. Graphene nanoribbons synthesized from molecular precursor polymerization on Au(110)

    SciTech Connect

    Massimi, Lorenzo; Ourdjini, Oualid; Della Pia, Ada; Mariani, Carlo; Betti, Maria Grazia; Cavaliere, Emanuele; Gavioli, Luca

    2015-06-23

    A spectroscopic study of 10,10-dibromo-9,9 bianthracene (DBBA) molecules deposited on the Au(110) surface is presented, by means of ultraviolet and X-ray photoemission, and X-ray absorption spectroscopy. Through a thermally activated procedure, these molecular precursors polymerize and eventually form graphene nanoribbons (GNRs) with atomically controlled shape and width, very important building blocks for several technological applications. The GNRs observed by scanning tunneling microscopy (STM) appear as short segments on top of the gold surface reconstruction, pointing out the delicate balance among surface diffusion and surface corrugation in their synthesis on the Au(110) surface.

  15. Self-assembly of flagellin on Au(111) surfaces.

    PubMed

    González Orive, Alejandro; Pissinis, Diego E; Diaz, Carolina; Miñán, Alejandro; Benítez, Guillermo A; Rubert, Aldo; Daza Millone, Antonieta; Rumbo, Martin; Hernández Creus, Alberto; Salvarezza, Roberto C; Schilardi, Patricia L

    2014-11-01

    The adsorption of flagellin monomers from Pseudomonas fluorescens on Au(111) has been studied by Atomic Force Microscopy (AFM), Scanning Tunneling Microscopy (STM), X-ray Photoelectron Spectroscopy (XPS), Surface Plasmon Resonance (SPR), and electrochemical techniques. Results show that flagellin monomers spontaneously self-assemble forming a monolayer thick protein film bounded to the Au surface by the more hydrophobic subunit and exposed to the environment the hydrophilic subunit. The films are conductive and allow allocation of electrochemically active cytochrome C. The self-assembled films could be used as biological platforms to build 3D complex molecular structures on planar metal surfaces and to functionalize metal nanoparticles. PMID:25112916

  16. Nuclear Shadowing and Select d+Au Observables

    NASA Astrophysics Data System (ADS)

    Adeluyi, Adeola; Fai, George

    2007-04-01

    Much of the complexity of the description of d+Au collisions in the framework of perturbative Quantum Chromodynamics (pQCD) derives from effects of the nuclear environment. Here we investigate the effects of the most recent available nuclear shadowing parametrization, the Hirai-Kumano-Nagai (HKN) nuclear parton distribution functions (nPDFs) and the updated Albino-Kniehl-Kramer (AKK) fragmentation functions on three select d+Au collision observables. We compare our results to available experimental data from the STAR and BRAHMS collaborations.

  17. Gold chloride clusters with Au(III) and Au(I) probed by FT-ICR mass spectrometry and MP2 theory.

    PubMed

    Lemke, Kono H

    2014-05-01

    Microsolvated clusters of gold chloride are probed by electrospray ionization mass spectrometry (ESI-MS) and scalar relativistic electronic structure calculations. Electrospray ionization of aqueous AuCl3 leads to mononuclear clusters of types [AuCl2](+)(H2O)n (n = 0-4), [AuOHCl](+)(H2O)n (n = 0-1) and [AuCl2](+)(HCl)2(H2O)n (n = 0-4). In addition, strong ion signals due to dinuclear [Au2Cl5-xOHx](+)(H2O)n (x = 0-1) are present in ESI mass spectra of aqueous AuCl3, with the abundance of individual dinuclear species controlled by the concentration-dependent variation of the precursor complexes [AuCl2-xOHx](+)(H2O)n and AuCl3. Equilibrium structures, energies and thermodynamic properties of mono- and dinuclear gold clusters have been predicted using MP2 and CCSD(T) theory, and these data have been applied to examine the influence of microsolvation on cluster stability. Specifically, results from CCSD(T) calculations indicate that non-covalently bound ion-neutral complexes Au(+)(Cl2)(H2O)n, with formal Au(I), are the dominant forms of mononuclear gold with n = 0-2, while higher hydrates (n > 2) are covalently bound [AuCl2](+)(H2O)n complexes in which gold exists as Au(III). MP2 calculations show that the lowest energy structure of dinuclear gold is an ion-molecule cluster [Au2Cl(Cl2)2](+) consisting of a single-bridged digold-chloronium ion bound end-on to two dichlorine ligands, with two higher energy isomers, single-bridged [Au2Cl3(Cl2)](+) and double-bridged [Au2Cl5](+) clusters. Finally, AuAu interactions in the singly-bridged clusters [Au2Cl(Cl2)2](+)(H2O)n and [Au2Cl3(Cl2)](+)(H2O)n are examined employing a wide range of computational tools, including natural bond order (NBO) analysis and localized orbital locator (LOL) profiles. PMID:24643288

  18. Interfacial electronic properties of the heterojunctions C{sub 60}/rubrene/Au and rubrene/C{sub 60}/Au

    SciTech Connect

    Cheng, Chiu-Ping; Chan, Yi-Wei; Hsueh, Chih-Feng; Pi, Tun-Wen

    2012-07-15

    Using synchrotron-radiation photoemission, we have studied the electronic structures of rubrene:C{sub 60} heterojunctions on Au substrates. The photoelectron spectra show that the interfacial properties at the C{sub 60}/rubrene/Au and rubrene/C{sub 60}/Au interfaces are asymmetric and do not follow the commutation rule. In the C{sub 60}/rubrene case, a gap state appearing in the initial deposition stage results from negative charges transferred from rubrene to C{sub 60}, while in the inverse deposition process, no strong chemical reaction could be found. A significant shift of the vacuum level induced by alignment of the charge neutrality levels of the two materials was observed in both cases. Furthermore, the charge transfer strongly enhances the dipole potential of the C{sub 60}/rubrene interface. The energy level diagrams show that the C{sub 60}-on-rubrene process has a superior number of advantages in the photovoltaic applications.

  19. Dihadron Azimuthal Correlations in Au+Au Collisions at s_NN = 200 GeV

    SciTech Connect

    Adare, A.; Awes, Terry C; Cianciolo, Vince; Efremenko, Yuri; Read Jr, Kenneth F; Silvermyr, David O; Sorensen, Soren P; Stankus, Paul W; Young, Glenn R; PHENIX, Collaboration

    2008-01-01

    Azimuthal angle ({Delta}{sup {phi}}) correlations are presented for a broad range of transverse momentum (0.4 < p{sub T} < 10 GeV/c) and centrality (0-92%) selections for charged hadrons from dijets in Au+Au collisions at {radical} s{sub NN} = 200 GeV. With increasing p{sub T}, the away-side {Delta}{sup {phi}} distribution evolves from a broad and relatively flat shape to a concave shape, then to a convex shape. Comparisons with p+p data suggest that the away-side distribution can be divided into a partially suppressed 'head' region centered at {Delta}{sup {phi}} {approx} {pi}, and an enhanced 'shoulder' region centered at {Delta}{sup {phi}} {approx} {pi} {+-} 1.1. The p{sub T} spectrum for the associated hadrons in the head region softens toward central collisions. The spectral slope for the shoulder region is independent of centrality and trigger p{sub T}. The properties of the near-side distributions are also modified relative to those in p+p collisions, reflected by the broadening of the jet shape in {Delta}{sup {phi}} and {Delta}{sup {eta}}, and an enhancement of the per-trigger yield. However, these modifications seem to be limited to p{sub T} {approx}< 4 GeV/c, above which both the hadron pair shape and per-trigger yield become similar to p+p collisions. These observations suggest that both the away- and near-side distributions contain a jet fragmentation component which dominates for p{sub T} {approx}> 5 GeV/c and a medium-induced component which is important for p{sub T} {approx}< 4 GeV/c. We also quantify the role of jets at intermediate and low p{sub T} through the yield of jet-induced pairs in comparison with binary scaled p+p pair yield. The yield of jet-induced pairs is suppressed at high pair proxy energy (sum of the p{sub T} magnitudes of the two hadrons) and is enhanced at low pair proxy energy. The former is consistent with jet quenching; the latter is consistent with the enhancement of soft hadron pairs due to transport of lost energy to lower p

  20. Synthesis and electrocatalytic activity of Au/Pt bimetallic nanodendrites for ethanol oxidation in alkaline medium.

    PubMed

    Han, Xinyi; Wang, Dawei; Liu, Dong; Huang, Jianshe; You, Tianyan

    2012-02-01

    Gold/Platinum (Au/Pt) bimetallic nanodendrites were successfully synthesized through seeded growth method using preformed Au nanodendrites as seeds and ascorbic acid as reductant. Cyclic voltammograms (CVs) of a series of Au/Pt nanodendrites modified electrodes in 1M KOH solution containing 1M ethanol showed that the electrocatalyst with a molar ratio (Au:Pt) of 3 exhibited the highest peak current density and the lowest onset potential. The peak current density of ethanol electro-oxidation on the Au(3)Pt(1) nanodendrites modified glassy carbon electrode (Au(3)Pt(1) electrode) is about 16, 12.5, and 4.5 times higher than those on the polycrystalline Pt electrode, polycrystalline Au electrode, and Au nanodendrites modified glassy carbon electrode (Au dendrites electrode), respectively. The oxidation peak potential of ethanol electro-oxidation on the Au(3)Pt(1) electrode is about 299 and 276 mV lower than those on the polycrystalline Au electrode and Au dendrites electrode, respectively. These results demonstrated that the Au/Pt bimetallic nanodendrites may find potential application in alkaline direct ethanol fuel cells (ADEFCs).

  1. Substrate-Structure Dependence of Ag Electromigration on Au-Precovered Si(111) Surfaces

    NASA Astrophysics Data System (ADS)

    Shi, Fangxiao; Shiraki, Ichiro; Nagao, Tadaaki; Hasegawa, Shuji

    2000-07-01

    Electromigration of Ag on Au-precovered Si(111) surfaces was investigated by in-situ ultrahigh vacuum scanning electron microscopy and μ-probe reflection-high-energy electron diffraction (RHEED). Migration behaviors of a Ag-film patch strongly depended on Au coverage θAu and corresponding surface structures. When θAu<0.7 monolayer (ML), the patch expanded preferentially towards the cathode to attain a maximum area in which the sum of Ag and Au coverages were always about 1 ML irrespective of θAu, resulting in two-dimensional (2D) alloy phases (showing \\sqrt{3}×\\sqrt{3} RHEED patterns) with different Au/Ag concentration ratios. The largest expansion of the patch area was achieved on a (5× 2+α-\\sqrt{3}×\\sqrt{3})-Au mixed phase structure (θAu˜ 0.7 ML). However, when θAu>0.7 ML, the patch expansion was greatly reduced. Especially on the β-\\sqrt{3}×\\sqrt{3}-Au surface (θAu˜ 1.0 ML), the patch showed no directional expansion towards the cathode. But Ag atoms were observed to migrate inside the patches on all substrates (including the β-\\sqrt{3}×\\sqrt{3}-Au surface) to form 3D islands near terrace edges.

  2. Electronic structure of Au-Ta alloys:. An X-ray spectroscopy study

    NASA Astrophysics Data System (ADS)

    Kuhn, M.; Sammynaiken, R.; Sham, T. K.

    1998-07-01

    Au-Ta alloys with the compositions of AuTa, AuTa 2 and AuTa 3, prepared by quenching from the melt, has been studied with X-ray diffraction, photoelectron spectroscopy (XPS) and X-ray absorption near-edge structure (XANES) measurements. It was found that while AuTa 3 is a single-phase solid solution, AuTa 2 and AuTa have mixed phases and that the Au and Ta 4f levels of the alloys shift to higher binding energy, relative to the pure metal; this is accompanied by a narrowing of the Au 5d component of the alloy d-band, which moves away from the Fermi level. This observation is interpreted in terms of a charge compensation model in which Au loses d charge but is overcompensated by s-p charge gain, resulting in a small net charge flow from Ta to Au. The observed Ta 4f binding energy shift is as predicted by electronegativity and indicates charge depletion at the Ta site. The notion of d charge depletion at both Au and Ta sites upon alloying is confirmed independently by XANES measurements which showed that the L 2,3 edge whiteline intensity for both Au and Ta increases as they become more dilute in the host, indicating an increase in d hole count. The experimental results compare favorably with a recent linear-augmented Slater-type-orbital (LASTO) calculations. The implications of these results are discussed.

  3. Elliptic flow in Au+Au collisions at square root(S)NN = 130 GeV.

    PubMed

    Ackermann, K H; Adams, N; Adler, C; Ahammed, Z; Ahmad, S; Allgower, C; Amsbaugh, J; Anderson, M; Anderssen, E; Arnesen, H; Arnold, L; Averichev, G S; Baldwin, A; Balewski, J; Barannikova, O; Barnby, L S; Baudot, J; Beddo, M; Bekele, S; Belaga, V V; Bellwied, R; Bennett, S; Bercovitz, J; Berger, J; Betts, W; Bichsel, H; Bieser, F; Bland, L C; Bloomer, M; Blyth, C O; Boehm, J; Bonner, B E; Bonnet, D; Bossingham, R; Botlo, M; Boucham, A; Bouillo, N; Bouvier, S; Bradley, K; Brady, F P; Braithwaite, E S; Braithwaite, W; Brandin, A; Brown, R L; Brugalette, G; Byrd, C; Caines, H; Calderón de la Barca Sánchez, M; Cardenas, A; Carr, L; Carroll, J; Castillo, J; Caylor, B; Cebra, D; Chatopadhyay, S; Chen, M L; Chen, W; Chen, Y; Chernenko, S P; Cherney, M; Chikanian, A; Choi, B; Chrin, J; Christie, W; Coffin, J P; Conin, L; Consiglio, C; Cormier, T M; Cramer, J G; Crawford, H J; Danilov, V I; Dayton, D; DeMello, M; Deng, W S; Derevschikov, A A; Dialinas, M; Diaz, H; DeYoung, P A; Didenko, L; Dimassimo, D; Dioguardi, J; Dominik, W; Drancourt, C; Draper, J E; Dunin, V B; Dunlop, J C; Eckardt, V; Edwards, W R; Efimov, L G; Eggert, T; Emelianov, V; Engelage, J; Eppley, G; Erazmus, B; Etkin, A; Fachini, P; Feliciano, C; Ferenc, D; Ferguson, M I; Fessler, H; Finch, E; Fine, V; Fisyak, Y; Flierl, D; Flores, I; Foley, K J; Fritz, D; Gagunashvili, N; Gans, J; Gazdzicki, M; Germain, M; Geurts, F; Ghazikhanian, V; Gojak, C; Grabski, J; Grachov, O; Grau, M; Greiner, D; Greiner, L; Grigoriev, V; Grosnick, D; Gross, J; Guilloux, G; Gushin, E; Hall, J; Hallman, T J; Hardtke, D; Harper, G; Harris, J W; He, P; Heffner, M; Heppelmann, S; Herston, T; Hill, D; Hippolyte, B; Hirsch, A; Hjort, E; Hoffmann, G W; Horsley, M; Howe, M; Huang, H Z; Humanic, T J; Hümmler, H; Hunt, W; Hunter, J; Igo, G J; Ishihara, A; Ivanshin, Y I; Jacobs, P; Jacobs, W W; Jacobson, S; Jared, R; Jensen, P; Johnson, I; Jones, P G; Judd, E; Kaneta, M; Kaplan, M; Keane, D; Kenney, V P; Khodinov, A; Klay, J; Klein, S R; Klyachko, A; Koehler, G; Konstantinov, A S; Kormilitsyne, V; Kotchenda, L; Kotov, I; Kovalenko, A D; Kramer, M; Kravtsov, P; Krueger, K; Krupien, T; Kuczewski, P; Kuhn, C; Kunde, G J; Kunz, C L; Kutuev, R K; Kuznetsov, A A; Lakehal-Ayat, L; Lamas-Valverde, J; Lamont, M A; Landgraf, J M; Lange, S; Lansdell, C P; Lasiuk, B; Laue, F; Lebedev, A; LeCompte, T; Leonhardt, W J; Leontiev, V M; Leszczynski, P; LeVine, M J; Li, Q; Li, Q; Li, Z; Liaw, C J; Lin, J; Lindenbaum, S J; Lindenstruth, V; Lindstrom, P J; Lisa, M A; Liu, H; Ljubicic, T; Llope, W J; LoCurto, G; Long, H; Longacre, R S; Lopez-Noriega, M; Lopiano, D; Love, W A; Lutz, J R; Lynn, D; Madansky, L; Maier, R; Majka, R; Maliszewski, A; Margetis, S; Marks, K; Marstaller, R; Martin, L; Marx, J; Matis, H S; Matulenko, Y A; Matyushevski, E A; McParland, C; McShane, T S; Meier, J; Melnick, Y; Meschanin, A; Middlekamp, P; Mikhalin, N; Miller, B; Milosevich, Z; Minaev, N G; Minor, B; Mitchell, J; Mogavero, E; Moiseenko, V A; Moltz, D; Moore, C F; Morozov, V; Morse, R; de Moura, M M; Munhoz, M G; Mutchler, G S; Nelson, J M; Nevski, P; Ngo, T; Nguyen, M; Nguyen, T; Nikitin, V A; Nogach, L V; Noggle, T; Norman, B; Nurushev, S B; Nussbaum, T; Nystrand, J; Odyniec, G; Ogawa, A; Ogilvie, C A; Olchanski, K; Oldenburg, M; Olson, D; Ososkov, G A; Ott, G; Padrazo, D; Paic, G; Pandey, S U; Panebratsev, Y; Panitkin, S Y; Pavlinov, A I; Pawlak, T; Pentia, M; Perevotchikov, V; Peryt, W; Petrov, V A; Pinganaud, W; Pirogov, S; Platner, E; Pluta, J; Polk, I; Porile, N; Porter, J; Poskanzer, A M; Potrebenikova, E; Prindle, D; Pruneau, C; Puskar-Pasewicz, J; Rai, G; Rasson, J; Ravel, O; Ray, R L; Razin, S V; Reichhold, D; Reid, J; Renfordt, R E; Retiere, F; Ridiger, A; Riso, J; Ritter, H G; Roberts, J B; Roehrich, D; Rogachevski, O V; Romero, J L; Roy, C; Russ, D; Rykov, V; Sakrejda, I; Sanchez, R; Sandler, Z; Sandweiss, J; Sappenfield, P; Saulys, A C; Savin, I; Schambach, J; Scharenberg, R P; Scheblien, J; Scheetz, R; Schlueter, R; Schmitz, N; Schroeder, L S; Schulz, M; Schüttauf, A; Sedlmeir, J; Seger, J; Seliverstov, D; Seyboth, J; Seyboth, P; Seymour, R; Shakaliev, E I; Shestermanov, K E; Shi, Y; Shimanskii, S S; Shuman, D; Shvetcov, V S; Skoro, G; Smirnov, N; Smykov, L P; Snellings, R; Solberg, K; Sowinski, J; Spinka, H M; Srivastava, B; Stephenson, E J; Stock, R; Stolpovsky, A; Stone, N; Stone, R; Strikhanov, M; Stringfellow, B; Stroebele, H; Struck, C; Suaide, A A; Sugarbaker, E; Suire, C; Symons, T J; Takahashi, J; Tang, A H; Tarchini, A; Tarzian, J; Thomas, J H; Tikhomirov, V; Szanto De Toledo, A; Tonse, S; Trainor, T; Trentalange, S; Tokarev, M; Tonjes, M B; Trofimov, V; Tsai, O; Turner, K; Ullrich, T; Underwood, D G; Vakula, I; Van Buren, G; VanderMolen, A M; Vanyashin, A; Vasilevski, I M; Vasiliev, A N; Vigdor, S E; Visser, G; Voloshin, S A; Vu, C; Wang, F; Ward, H; Weerasundara, D; Weidenbach, R; Wells, R; Wells, R; Wenaus, T; Westfall, G D; Whitfield, J P; Whitten, C; Wieman, H; Willson, R; Wilson, K; Wirth, J; Wisdom, J; Wissink, S W; Witt, R; Wolf, J; Wood, L; Xu, N; Xu, Z; Yakutin, A E; Yamamoto, E; Yang, J; Yepes, P; Yokosawa, A; Yurevich, V I; Zanevski, Y V; Zhang, J; Zhang, W M; Zhu, J; Zimmerman, D; Zoulkarneev, R; Zubarev, A N

    2001-01-15

    Elliptic flow from nuclear collisions is a hadronic observable sensitive to the early stages of system evolution. We report first results on elliptic flow of charged particles at midrapidity in Au+Au collisions at square root(S)NN = 130 GeV using the STAR Time Projection Chamber at the Relativistic Heavy Ion Collider. The elliptic flow signal, v2, averaged over transverse momentum, reaches values of about 6% for relatively peripheral collisions and decreases for the more central collisions. This can be interpreted as the observation of a higher degree of thermalization than at lower collision energies. Pseudorapidity and transverse momentum dependence of elliptic flow are also presented.

  4. Strong non-linear effects in the chiroptical properties of the ligand-exchanged Au38 and Au40 clusters

    NASA Astrophysics Data System (ADS)

    Knoppe, Stefan; Dass, Amala; Bürgi, Thomas

    2012-06-01

    Ligand exchange reactions on size-selected Au38(2-PET)24 and Au40(2-PET)24 clusters (2-PET: 2-phenylethylthiol) with mono- and bi-dentate chiral thiols were performed. The reactions were monitored with MALDI mass spectrometry and the arising chiroptical properties were compared to the number of incorporated chiral ligands. Only a small fraction of chiral ligands is needed to induce significant optical activity to the clusters. The use of bidentate 1,1'-binaphthyl-2,2'-dithiol (BINAS) leads to slow exchange, but the optical activity measured is strong. Moreover, a non-linear behaviour between optical activity and the number of chiral ligands is found in the BINAS case for both Au38 and Au40, which may indicate different exchange rates of enantiopure BINAS with the enantiomers of inherently chiral (but racemic) clusters. This is ascribed to effects arising from the bidentate nature of BINAS. In contrast, the use of monodentate camphor-10-thiol (CamSH) leads to comparably fast exchange on both clusters. The arising optical activity is weak. This is the first study where chiroptical effects are directly correlated with the composition of the ligand shell.Ligand exchange reactions on size-selected Au38(2-PET)24 and Au40(2-PET)24 clusters (2-PET: 2-phenylethylthiol) with mono- and bi-dentate chiral thiols were performed. The reactions were monitored with MALDI mass spectrometry and the arising chiroptical properties were compared to the number of incorporated chiral ligands. Only a small fraction of chiral ligands is needed to induce significant optical activity to the clusters. The use of bidentate 1,1'-binaphthyl-2,2'-dithiol (BINAS) leads to slow exchange, but the optical activity measured is strong. Moreover, a non-linear behaviour between optical activity and the number of chiral ligands is found in the BINAS case for both Au38 and Au40, which may indicate different exchange rates of enantiopure BINAS with the enantiomers of inherently chiral (but racemic) clusters

  5. Low frequency noise in the unstable contact region of Au-to-Au microcontact for microelectromechanical system switches

    NASA Astrophysics Data System (ADS)

    Qiu, Haodong; Wang, Hong; Ke, Feixiang

    2014-06-01

    The noise behavior of Au-to-Au microcontact for microelectromechanical system switches has been experimentally studied in the unstable contact region. The results suggest that the electrical conduction remains nonmetallic at the initial stage during contact formation due to the existence of alien films, and traps in the alien layer located at the contact interface could play an important role in determining the conduction noise. The conduction fluctuation induced by electron trapping-detrapping associated with the hydrocarbon layer is found to be an intrinsic noise source contributing to the low frequency noise in the unstable contact region.

  6. Selective-Area Growth of Thick Diamond Films Using Chemically Stable Masks of Ru/Au and Mo/Au

    NASA Astrophysics Data System (ADS)

    Nagase, Masanori; Watanabe, Katsumi; Umezawa, Hitoshi; Shikata, Shinichi

    2012-07-01

    Selective-area growth of diamond films in microwave-plasma chemical vapor deposition was performed using newly developed masks. By forming chemically stable masks made of Ru/Au or Mo/Au, which have high melting points, good adhesion to diamond, and difficulty in forming carbide compounds, patterned diamond films with a large thickness of 50 µm, a large area of 5 mm2, and a high orientation in the [001] direction were successfully grown on (001) diamond substrates without degradation of the crystal quality of masked areas.

  7. ΛΛ correlation function in Au + Au collisions at √sNN = 200 GeV

    DOE PAGESBeta

    Adamczyk, L.

    2015-01-12

    In this study, we present ΛΛ correlation measurements in heavy-ion collisions for Au+Au collisions at √sNN = 200 GeV using the STAR experiment at the Relativistic Heavy-Ion Collider (RHIC). The Lednický-Lyuboshitz analytical model has been used to fit the data to obtain a source size, a scattering length and an effective range. Implications of the measurement of the ΛΛ correlation function and interaction parameters for di-hyperon searches are discussed.

  8. ΛΛ correlation function in Au + Au collisions at √sNN = 200 GeV

    SciTech Connect

    Adamczyk, L.

    2015-01-12

    In this study, we present ΛΛ correlation measurements in heavy-ion collisions for Au+Au collisions at √sNN = 200 GeV using the STAR experiment at the Relativistic Heavy-Ion Collider (RHIC). The Lednický-Lyuboshitz analytical model has been used to fit the data to obtain a source size, a scattering length and an effective range. Implications of the measurement of the ΛΛ correlation function and interaction parameters for di-hyperon searches are discussed.

  9. Pion-Kaon correlations in central Au+Au collisions at square root [sNN] = 130 GeV.

    PubMed

    Adams, J; Adler, C; Aggarwal, M M; Ahammed, Z; Amonett, J; Anderson, B D; Anderson, M; Arkhipkin, D; Averichev, G S; Badyal, S K; Balewski, J; Barannikova, O; Barnby, L S; Baudot, J; Bekele, S; Belaga, V V; Bellwied, R; Berger, J; Bezverkhny, B I; Bhardwaj, S; Bhaskar, P; Bhati, A K; Bichsel, H; Billmeier, A; Bland, L C; Blyth, C O; Bonner, B E; Botje, M; Boucham, A; Brandin, A; Bravar, A; Cadman, R V; Cai, X Z; Caines, H; Calderón de la Barca Sánchez, M; Carroll, J; Castillo, J; Castro, M; Cebra, D; Chaloupka, P; Chattopadhyay, S; Chen, H F; Chen, Y; Chernenko, S P; Cherney, M; Chikanian, A; Choi, B; Christie, W; Coffin, J P; Cormier, T M; Cramer, J G; Crawford, H J; Das, D; Das, S; Derevschikov, A A; Didenko, L; Dietel, T; Dong, X; Draper, J E; Du, F; Dubey, A K; Dunin, V B; Dunlop, J C; Dutta Majumdar, M R; Eckardt, V; Efimov, L G; Emelianov, V; Engelage, J; Eppley, G; Erazmus, B; Fachini, P; Faine, V; Faivre, J; Fatemi, R; Filimonov, K; Filip, P; Finch, E; Fisyak, Y; Flierl, D; Foley, K J; Fu, J; Gagliardi, C A; Ganti, M S; Gutierrez, T D; Gagunashvili, N; Gans, J; Gaudichet, L; Germain, M; Geurts, F; Ghazikhanian, V; Ghosh, P; Gonzalez, J E; Grachov, O; Grigoriev, V; Gronstal, S; Grosnick, D; Guedon, M; Guertin, S M; Gupta, A; Gushin, E; Hallman, T J; Hardtke, D; Harris, J W; Heinz, M; Henry, T W; Heppelmann, S; Herston, T; Hippolyte, B; Hirsch, A; Hjort, E; Hoffmann, G W; Horsley, M; Huang, H Z; Huang, S L; Humanic, T J; Igo, G; Ishihara, A; Jacobs, P; Jacobs, W W; Janik, M; Johnson, I; Jones, P G; Judd, E G; Kabana, S; Kaneta, M; Kaplan, M; Keane, D; Kiryluk, J; Kisiel, A; Klay, J; Klein, S R; Klyachko, A; Koetke, D D; Kollegger, T; Konstantinov, A S; Kopytine, M; Kotchenda, L; Kovalenko, A D; Kramer, M; Kravtsov, P; Krueger, K; Kuhn, C; Kulikov, A I; Kumar, A; Kunde, G J; Kunz, C L; Kutuev, R Kh; Kuznetsov, A A; Lamont, M A C; Landgraf, J M; Lange, S; Lansdell, C P; Lasiuk, B; Laue, F; Lauret, J; Lebedev, A; Lednický, R; Leontiev, V M; LeVine, M J; Li, C; Li, Q; Lindenbaum, S J; Lisa, M A; Liu, F; Liu, L; Liu, Z; Liu, Q J; Ljubicic, T; Llope, W J; Long, H; Longacre, R S; Lopez-Noriega, M; Love, W A; Ludlam, T; Lynn, D; Ma, J; Ma, Y G; Magestro, D; Mahajan, S; Mangotra, L K; Mahapatra, D P; Majka, R; Manweiler, R; Margetis, S; Markert, C; Martin, L; Marx, J; Matis, H S; Matulenko, Yu A; McShane, T S; Meissner, F; Melnick, Yu; Meschanin, A; Messer, M; Miller, M L; Milosevich, Z; Minaev, N G; Mironov, C; Mishra, D; Mitchell, J; Mohanty, B; Molnar, L; Moore, C F; Mora-Corral, M J; Morozov, V; de Moura, M M; Munhoz, M G; Nandi, B K; Nayak, S K; Nayak, T K; Nelson, J M; Nevski, P; Nikitin, V A; Nogach, L V; Norman, B; Nurushev, S B; Odyniec, G; Ogawa, A; Okorokov, V; Oldenburg, M; Olson, D; Paic, G; Pandey, S U; Pal, S K; Panebratsev, Y; Panitkin, S Y; Pavlinov, A I; Pawlak, T; Perevoztchikov, V; Peryt, W; Petrov, V A; Phatak, S C; Picha, R; Planinic, M; Pluta, J; Porile, N; Porter, J; Poskanzer, A M; Potekhin, M; Potrebenikova, E; Potukuchi, B V K S; Prindle, D; Pruneau, C; Putschke, J; Rai, G; Rakness, G; Raniwala, R; Raniwala, S; Ravel, O; Ray, R L; Razin, S V; Reichhold, D; Reid, J G; Renault, G; Retiere, F; Ridiger, A; Ritter, H G; Roberts, J B; Rogachevski, O V; Romero, J L; Rose, A; Roy, C; Ruan, L J; Rykov, V; Sahoo, R; Sakrejda, I; Salur, S; Sandweiss, J; Savin, I; Schambach, J; Scharenberg, R P; Schmitz, N; Schroeder, L S; Schweda, K; Seger, J; Seliverstov, D; Seyboth, P; Shahaliev, E; Shao, M; Sharma, M; Shestermanov, K E; Shimanskii, S S; Singaraju, R N; Simon, F; Skoro, G; Smirnov, N; Snellings, R; Sood, G; Sorensen, P; Sowinski, J; Spinka, H M; Srivastava, B; Stanislaus, S; Stock, R; Stolpovsky, A; Strikhanov, M; Stringfellow, B; Struck, C; Suaide, A A P; Sugarbaker, E; Suire, C; Sumbera, M; Surrow, B; Symons, T J M; Szanto de Toledo, A; Szarwas, P; Tai, A; Takahashi, J; Tang, A H; Thein, D; Thomas, J H; Tikhomirov, V; Tokarev, M; Tonjes, M B; Trainor, T A; Trentalange, S; Tribble, R E; Trivedi, M D; Trofimov, V; Tsai, O; Ullrich, T; Underwood, D G; Van Buren, G; VanderMolen, A M; Vasiliev, A N; Vasiliev, M; Vigdor, S E; Viyogi, Y P; Voloshin, S A; Waggoner, W; Wang, F; Wang, G; Wang, X L; Wang, Z M; Ward, H; Watson, J W; Wells, R; Westfall, G D; Whitten, C; Wieman, H; Willson, R; Wissink, S W; Witt, R; Wood, J; Wu, J; Xu, N; Xu, Z; Xu, Z Z; Yakutin, A E; Yamamoto, E; Yang, J; Yepes, P; Yurevich, V I; Zanevski, Y V; Zborovský, I; Zhang, H; Zhang, H Y; Zhang, W M; Zhang, Z P; Zołnierczuk, P A; Zoulkarneev, R; Zoulkarneeva, J; Zubarev, A N

    2003-12-31

    Pion-kaon correlation functions are constructed from central Au+Au STAR data taken at sqrt[s(NN)]=130 GeV by the STAR detector at the Relativistic Heavy Ion Collider (RHIC). The results suggest that pions and kaons are not emitted at the same average space-time point. Space-momentum correlations, i.e., transverse flow, lead to a space-time emission asymmetry of pions and kaons that is consistent with the data. This result provides new independent evidence that the system created at RHIC undergoes a collective transverse expansion. PMID:14754044

  10. Direct observation of dijets in central Au+Au collisions at sqrt[sNN]=200 GeV.

    PubMed

    Adams, J; Aggarwal, M M; Ahammed, Z; Amonett, J; Anderson, B D; Anderson, M; Arkhipkin, D; Averichev, G S; Bai, Y; Balewski, J; Barannikova, O; Barnby, L S; Baudot, J; Bekele, S; Belaga, V V; Bellingeri-Laurikainen, A; Bellwied, R; Bezverkhny, B I; Bhardwaj, S; Bhasin, A; Bhati, A K; Bichsel, H; Bielcik, J; Bielcikova, J; Bland, L C; Blyth, C O; Blyth, S-L; Bonner, B E; Botje, M; Bouchet, J; Brandin, A V; Bravar, A; Bystersky, M; Cadman, R V; Cai, X Z; Caines, H; Calderón de la Barca Sánchez, M; Castillo, J; Catu, O; Cebra, D; Chajecki, Z; Chaloupka, P; Chattopadhyay, S; Chen, H F; Chen, J H; Chen, Y; Cheng, J; Cherney, M; Chikanian, A; Choi, H A; Christie, W; Coffin, J P; Cormier, T M; Cosentino, M R; Cramer, J G; Crawford, H J; Das, D; Das, S; Daugherity, M; de Moura, M M; Dedovich, T G; Dephillips, M; Derevschikov, A A; Didenko, L; Dietel, T; Djawotho, P; Dogra, S M; Dong, W J; Dong, X; Draper, J E; Du, F; Dunin, V B; Dunlop, J C; Dutta Mazumdar, M R; Eckardt, V; Edwards, W R; Efimov, L G; Emelianov, V; Engelage, J; Eppley, G; Erazmus, B; Estienne, M; Fachini, P; Fatemi, R; Fedorisin, J; Filimonov, K; Filip, P; Finch, E; Fine, V; Fisyak, Y; Fu, J; Gagliardi, C A; Gaillard, L; Gans, J; Ganti, M S; Ghazikhanian, V; Ghosh, P; Gonzalez, J E; Gorbunov, Y G; Gos, H; Grebenyuk, O; Grosnick, D; Guertin, S M; Guimaraes, K S F F; Guo, Y; Gupta, N; Gutierrez, T D; Haag, B; Hallman, T J; Hamed, A; Harris, J W; He, W; Heinz, M; Henry, T W; Hepplemann, S; Hippolyte, B; Hirsch, A; Hjort, E; Hoffmann, G W; Horner, M J; Huang, H Z; Huang, S L; Hughes, E W; Humanic, T J; Igo, G; Jacobs, P; Jacobs, W W; Jakl, P; Jia, F; Jiang, H; Jones, P G; Judd, E G; Kabana, S; Kang, K; Kapitan, J; Kaplan, M; Keane, D; Kechechyan, A; Khodyrev, V Yu; Kim, B C; Kiryluk, J; Kisiel, A; Kislov, E M; Klein, S R; Koetke, D D; Kollegger, T; Kopytine, M; Kotchenda, L; Kouchpil, V; Kowalik, K L; Kramer, M; Kravtsov, P; Kravtsov, V I; Krueger, K; Kuhn, C; Kulikov, A I; Kumar, A; Kuznetsov, A A; Lamont, M A C; Landgraf, J M; Lange, S; Lapointe, S; Laue, F; Lauret, J; Lebedev, A; Lednicky, R; Lee, C-H; Lehocka, S; Levine, M J; Li, C; Li, Q; Li, Y; Lin, G; Lindenbaum, S J; Lisa, M A; Liu, F; Liu, H; Liu, J; Liu, L; Liu, Z; Ljubicic, T; Llope, W J; Long, H; Longacre, R S; Lopez-Noriega, M; Love, W A; Lu, Y; Ludlam, T; Lynn, D; Ma, G L; Ma, J G; Ma, Y G; Magestro, D; Mahapatra, D P; Majka, R; Mangotra, L K; Manweiler, R; Margetis, S; Markert, C; Martin, L; Matis, H S; Matulenko, Yu A; McClain, C J; McShane, T S; Melnick, Yu; Meschanin, A; Miller, M L; Minaev, N G; Mioduszewski, S; Mironov, C; Mischke, A; Mishra, D K; Mitchell, J; Mohanty, B; Molnar, L; Moore, C F; Morozov, D A; Munhoz, M G; Nandi, B K; Nattrass, C; Nayak, T K; Nelson, J M; Netrakanti, P K; Nikitin, V A; Nogach, L V; Nurushev, S B; Odyniec, G; Ogawa, A; Okorokov, V; Oldenburg, M; Olson, D; Pachr, M; Pal, S K; Panebratsev, Y; Panitkin, S Y; Pavlinov, A I; Pawlak, T; Peitzmann, T; Perevoztchikov, V; Perkins, C; Peryt, W; Petrov, V A; Phatak, S C; Picha, R; Planinic, M; Pluta, J; Poljak, N; Porile, N; Porter, J; Poskanzer, A M; Potekhin, M; Potrebenikova, E; Potukuchi, B V K S; Prindle, D; Pruneau, C; Putschke, J; Rakness, G; Raniwala, R; Raniwala, S; Ray, R L; Razin, S V; Reinnarth, J; Relyea, D; Retiere, F; Ridiger, A; Ritter, H G; Roberts, J B; Rogachevskiy, O V; Romero, J L; Rose, A; Roy, C; Ruan, L; Russcher, M J; Sahoo, R; Sakrejda, I; Salur, S; Sandweiss, J; Sarsour, M; Sazhin, P S; Schambach, J; Scharenberg, R P; Schmitz, N; Schweda, K; Seger, J; Selyuzhenkov, I; Seyboth, P; Shabetai, A; Shahaliev, E; Shao, M; Sharma, M; Shen, W Q; Shimanskiy, S S; Sichtermann, E; Simon, F; Singaraju, R N; Smirnov, N; Snellings, R; Sood, G; Sorensen, P; Sowinski, J; Speltz, J; Spinka, H M; Srivastava, B; Stadnik, A; Stanislaus, T D S; Stock, R; Stolpovsky, A; Strikhanov, M; Stringfellow, B; Suaide, A A P; Sugarbaker, E; Sumbera, M; Sun, Z; Surrow, B; Swanger, M; Symons, T J M; Szanto de Toledo, A; Tai, A; Takahashi, J; Tang, A H; Tarnowsky, T; Thein, D; Thomas, J H; Timmins, A R; Timoshenko, S; Tokarev, M; Trentalange, S; Tribble, R E; Tsai, O D; Ulery, J; Ullrich, T; Underwood, D G; Van Buren, G; van der Kolk, N; van Leeuwen, M; Vander Molen, A M; Varma, R; Vasilevski, I M; Vasiliev, A N; Vernet, R; Vigdor, S E; Viyogi, Y P; Vokal, S; Voloshin, S A; Waggoner, W T; Wang, F; Wang, G; Wang, J S; Wang, X L; Wang, Y; Watson, J W; Webb, J C; Westfall, G D; Wetzler, A; Whitten, C; Wieman, H; Wissink, S W; Witt, R; Wood, J; Wu, J; Xu, N; Xu, Q H; Xu, Z; Yepes, P; Yoo, I-K; Yurevich, V I; Zhan, W; Zhang, H; Zhang, W M; Zhang, Y; Zhang, Z P; Zhao, Y; Zhong, C; Zoulkarneev, R; Zoulkarneeva, Y; Zubarev, A N; Zuo, J X

    2006-10-20

    The STAR Collaboration at the Relativistic Heavy Ion Collider reports measurements of azimuthal correlations of high transverse momentum (pT) charged hadrons in Au+Au collisions at higher pT than reported previously. As (pT) is increased, a narrow, back-to-back peak emerges above the decreasing background, providing a clear dijet signal for all collision centralities studied. Using these correlations, we perform a systematic study of dijet production and suppression in nuclear collisions, providing new constraints on the mechanisms underlying partonic energy loss in dense matter. PMID:17155388

  11. Measurement of J/ψ Azimuthal Anisotropy in Au+Au Collisions at sNN=200GeV

    NASA Astrophysics Data System (ADS)

    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.; Averichev, G. S.; Balewski, J.; Banerjee, A.; Barnovska, Z.; Beavis, D. R.; Bellwied, R.; Betancourt, M. J.; Betts, R. 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.; Bruna, E.; Bültmann, S.; Bunzarov, I.; Burton, T. P.; Butterworth, J.; Cai, X. Z.; 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, J. Y.; Chen, L.; Cheng, J.; Cherney, M.; Chikanian, A.; Christie, W.; Chung, P.; Chwastowski, J.; Codrington, M. J. M.; Corliss, R.; 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.; Derradi de Souza, R.; Dhamija, S.; di Ruzza, B.; Didenko, L.; Ding, F.; Dion, A.; Djawotho, P.; Dong, X.; Drachenberg, J. L.; Draper, J. E.; Du, C. M.; Dunkelberger, L. E.; Dunlop, J. C.; Efimov, L. G.; Elnimr, M.; Engelage, J.; Eppley, G.; Eun, L.; Evdokimov, O.; Fatemi, R.; Fazio, S.; Fedorisin, J.; Fersch, R. G.; Filip, P.; Finch, E.; Fisyak, Y.; Flores, E.; Gagliardi, C. A.; Gangadharan, D. R.; Garand, D.; Geurts, F.; Gibson, A.; Gliske, S.; Grebenyuk, O. G.; Grosnick, D.; Gupta, A.; Gupta, S.; Guryn, W.; Haag, B.; Hajkova, O.; Hamed, A.; Han, L.-X.; Harris, J. W.; Hays-Wehle, J. P.; Heppelmann, S.; Hirsch, A.; Hoffmann, G. W.; Hofman, D. J.; Horvat, S.; Huang, B.; Huang, H. Z.; Huck, P.; Humanic, T. J.; Igo, G.; Jacobs, W. W.; Jena, C.; Judd, E. G.; Kabana, S.; Kang, K.; Kapitan, J.; Kauder, K.; Ke, H. W.; Keane, D.; Kechechyan, A.; Kesich, A.; Kikola, D. P.; Kiryluk, J.; Kisel, I.; Kisiel, A.; Klein, S. R.; Koetke, D. D.; Kollegger, T.; Konzer, J.; Koralt, I.; Korsch, W.; Kotchenda, L.; Kravtsov, P.; Krueger, K.; Kulakov, I.; Kumar, L.; Lamont, M. A. C.; Landgraf, J. M.; Landry, K. D.; LaPointe, S.; Lauret, J.; Lebedev, A.; Lednicky, R.; Lee, J. H.; Leight, W.; LeVine, M. J.; Li, C.; Li, W.; Li, X.; Li, X.; Li, Y.; Li, Z. M.; Lima, L. M.; Lisa, M. A.; Liu, F.; Ljubicic, T.; Llope, W. J.; Longacre, R. S.; Lu, Y.; Luo, X.; Luszczak, A.; 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.; Mioduszewski, S.; Mitrovski, M. K.; Mohammed, Y.; Mohanty, B.; Mondal, M. M.; Munhoz, M. G.; Mustafa, M. K.; Naglis, M.; Nandi, B. K.; Nasim, Md.; Nayak, T. K.; Nelson, J. M.; Nogach, L. V.; Novak, J.; Odyniec, G.; Ogawa, A.; Oh, K.; Ohlson, A.; Okorokov, V.; Oldag, E. W.; Oliveira, R. A. N.; Olson, D.; 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.; Powell, C. B.; Pruneau, C.; Pruthi, N. K.; Przybycien, M.; Pujahari, P. R.; Putschke, J.; Qiu, H.; 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.; Ruan, L.; Rusnak, J.; Sahoo, N. R.; Sahu, P. K.; Sakrejda, I.; Salur, S.; Sandacz, A.; Sandweiss, J.; Sangaline, E.; Sarkar, A.; Schambach, J.; Scharenberg, R. P.; Schmah, A. M.; Schmidke, B.; Schmitz, N.; Schuster, T. R.; Seger, J.; Seyboth, P.; Shah, N.; Shahaliev, E.; Shao, M.; Sharma, B.; Sharma, M.; Shi, S. S.; Shou, Q. Y.; Sichtermann, E. P.; Singaraju, R. N.; Skoby, M. J.; Smirnov, D.; Smirnov, N.; Solanki, D.; Sorensen, P.; deSouza, U. G.; Spinka, H. M.; Srivastava, B.; Stanislaus, T. D. S.; Stevens, J. R.; Stock, R.; Strikhanov, M.; Stringfellow, B.; Suaide, A. A. P.; Suarez, M. C.; Sumbera, M.; Sun, X. M.; Sun, Y.; Sun, Z.; Surrow, B.; Svirida, D. N.; Symons, T. J. M.; Szanto de Toledo, A.; Takahashi, J.; Tang, A. H.; Tang, Z.; Tarini, L. H.; Tarnowsky, T.; Thomas, J. H.; Tian, J.; 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.; Vanfossen, J. A., Jr.; Varma, R.; Vasconcelos, G. M. S.; Videbæk, F.; Viyogi, Y. P.; Vokal, S.; Voloshin, S. A.; Vossen, A.; Wada, M.; Wang, F.; Wang, G.; Wang, H.; Wang, J. S.; Wang, Q.; Wang, X. L.; Wang, Y.; Webb, G.; Webb, J. C.; Westfall, G. D.; Whitten, C., Jr.; Wieman, H.; Wissink, S. W.; Witt, R.; Wu, Y. F.; Xiao, Z.; Xie, W.; Xin, K.; Xu, H.; Xu, N.; Xu, Q. H.; Xu, W.; Xu, Y.; Xu, Z.; Xue, L.; Yang, Y.; Yang, Y.; Yepes, P.; Yi, L.; Yip, K.; Yoo, I.-K.; Zawisza, M.; Zbroszczyk, H.; Zhang, J. B.; 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.

    2013-08-01

    The measurement of J/ψ azimuthal anisotropy is presented as a function of transverse momentum for different centralities in Au+Au collisions at sNN=200GeV. The measured J/ψ elliptic flow is consistent with zero within errors for transverse momentum between 2 and 10GeV/c. Our measurement suggests that J/ψ particles with relatively large transverse momenta are not dominantly produced by coalescence from thermalized charm quarks, when comparing to model calculations.

  12. Measurement of inclusive antiprotons from Au+Au collisions at square root of s(NN) = 130 GeV.

    PubMed

    Adler, C; Ahammed, Z; Allgower, C; Amonett, J; Anderson, B D; Anderson, M; Averichev, G S; Balewski, J; Barannikova, O; 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; Cadman, R V; Caines, H; Calderón de la Barca Sánchez, 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; Coffin, J P; Cormier, T M; Cramer, J G; Crawford, H J; DeMello, M; Deng, W S; Derevschikov, 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; Filimonov, K; Finch, E; Fisyak, Y; Flierl, D; Foley, K J; Fu, J; Gagliardi, C A; Gagunashvili, N; Gans, J; Gaudichet, L; Germain, M; Geurts, F; Ghazikhanian, V; Grabski, J; Grachov, O; Grigoriev, V; Guedon, M; Gushin, 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, Y 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; Klein, S R; Klyachko, A; Konstantinov, A S; Kotchenda, L; Kovalenko, A D; Kramer, M; Kravtsov, P; Krueger, K; Kuhn, C; Kulikov, A I; Kunde, G J; Kunz, C L; Kutuev, R K; Kuznetsov, A A; Lakehal-Ayat, L; Lamas-Valverde, J; Lamont, M A; Landgraf, J M; Lange, S; Lansdell, C P; Lasiuk, B; Laue, F; Lebedev, A; Lednický, R; Leontiev, V M; LeVine, M J; Li, Q; Lindenbaum, S J; Lisa, M A; Liu, F; Liu, L; Liu, Z; Liu, Q J; Ljubicic, T; Llope, W J; LoCurto, G; Long, H; Longacre, R S; Lopez-Noriega, M; Love, W A; Lynn, D; Majka, R; Margetis, S; Martin, L; Marx, J; Matis, H S; Matulenko, Y A; McShane, T S; Meissner, F; Melnick, Y; Meschanin, A; Messer, M; Miller, M L; Milosevich, Z; Minaev, N G; Mitchell, J; Moiseenko, V A; 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, G; Ogawa, A; Okorokov, V; Oldenburg, M; Olson, D; Paic, G; Pandey, S U; Panebratsev, Y; Panitkin, S Y; Pavlinov, A I; Pawlak, T; Perevoztchikov, V; Peryt, W; Petrov, V A; Platner, E; Pluta, J; Porile, N; Porter, J; Poskanzer, A M; Potrebenikova, E; Prindle, D; Pruneau, C; Radomski, S; Rai, G; Ravel, O; Ray, R L; Razin, S V; Reichhold, D; Reid, J G; Retiere, F; Ridiger, A; Ritter, H G; Roberts, J B; Rogachevski, O V; Romero, J L; Roy, C; Rykov, V; Sakrejda, I; Sandweiss, J; Saulys, A C; Savin, I; Schambach, J; Scharenberg, R P; Schmitz, N; Schroeder, L S; Schüttauf, A; Schweda, K; Seger, J; Seliverstov, D; Seyboth, P; Shahaliev, E; Shestermanov, K E; Shimanskii, S S; Shvetcov, V S; Skoro, G; Smirnov, N; Snellings, R; Sowinski, J; Spinka, H M; Srivastava, B; Stephenson, E J; Stock, R; Stolpovsky, A; Strikhanov, M; Stringfellow, B; Struck, C; Suaide, A A; Sugarbaker, E; Suire, C; Sumbera, M; Symons, T J; de Toledo, A S; Szarwas, P; Takahashi, J; Tang, A H; Thomas, J H; Thompson, M; Tikhomirov, V; Trainor, T A; Trentalange, S; Tribble, R E; Tokarev, M; Tonjes, M B; Trofimov, V; Tsai, O; Turner, K; Ullrich, T; Underwood, D G; Van Buren, G; VanderMolen, A M; Vanyashin, A; Vasilevski, I M; Vasiliev, A N; Vigdor, S E; Voloshin, S A; Wang, F; Ward, H; Watson, J W; Wells, R; Wenaus, T; Westfall, G D; Whitten, C; Wieman, H; Willson, R; Wissink, S W; Witt, R; Xu, N; Xu, Z; Yakutin, A E; Yamamoto, E; Yang, J; Yepes, P; Yurevich, V I; Zanevski, Y V; Zborovský, I; Zhang, H; Zhang, W M; Zoulkarneev, R; Zubarev, A N

    2001-12-24

    We report the first measurement of inclusive antiproton production at midrapidity in Au+Au collisions at square root of s(NN) = 130 GeV by the STAR experiment at RHIC. The antiproton transverse mass distributions in the measured transverse momentum range of 0.25

  13. Pion Interferometry of square root of (s(NN)) =130 GeV Au + Au collisions at RHIC.

    PubMed

    Adler, C; Ahammed, Z; Allgower, C; Amonett, J; Anderson, B D; Anderson, M; Averichev, G S; Balewski, J; Barannikova, O; 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; Bossingham, R; Boucham, A; Brandin, A; Cadman, R V; Caines, H; Calderón De La Barca Sánchez, 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; Coffin, J P; Conin, L; Cormier, T M; Cramer, J G; Crawford, H J; DeMello, M; Deng, W S; Derevschikov, 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, Y; Flierl, D; Foley, K J; Fu, J; Gagunashvili, N; Gans, J; Gaudichet, L; Germain, M; Geurts, F; Ghazikhanian, V; Grabski, J; Grachov, O; Greiner, D; Grigoriev, V; Guedon, M; Gushin, 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, Y 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; Klein, S R; Klyachko, A; Konstantinov, A S; Kotchenda, L; Kovalenko, A D; Kramer, M; Kravtsov, P; Krueger, K; Kuhn, C; Kulikov, A I; Kunde, G J; Kunz, C L; Kutuev, R K; Kuznetsov, A A; Lakehal-Ayat, L; Lamas-Valverde, J; Lamont, M A; Landgraf, J M; Lange, S; Lansdell, C P; Lasiuk, B; Laue, F; Lebedev, A; LeCompte, T; Lednický, R; Leontiev, V M; LeVine, M J; Li, Q; Li, Q; Lindenbaum, S J; Lisa, M A; Ljubicic, T; Llope, W J; LoCurto, G; Long, H; Longacre, R S; Lopez-Noriega, M; Love, W A; Lynn, D; Majka, R; Margetis, S; Martin, L; Marx, J; Matis, H S; Matulenko, Y A; McShane, T S; Meissner, F; Melnick, Y; Meschanin, A; 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, G; Ogawa, A; Okorokov, V; Oldenburg, M; Olson, D; Paic, G; Pandey, S U; Panebratsev, Y; Panitkin, S Y; Pavlinov, A I; Pawlak, T; Perevoztchikov, V; Peryt, W; Petrov, V A; Pinganaud, W; Platner, E; Pluta, J; Porile, N; Porter, J; Poskanzer, A M; Potrebenikova, E; Prindle, D; Pruneau, C; Radomski, S; Rai, G; Ravel, O; Ray, R L; Razin, S V; Reichhold, D; Reid, J G; Retiere, F; Ridiger, A; Ritter, H G; Roberts, J B; Rogachevski, O V; Romero, J L; Roy, C; Russ, D; Rykov, V; Sakrejda, I; Sandweiss, J; Saulys, A C; Savin, I; Schambach, J; Scharenberg, R P; Schweda, K; Schmitz, N; Schroeder, L S; Schüttauf, A; Seger, J; Seliverstov, D; Seyboth, P; Shahaliev, E; Shestermanov, K E; Shimanskii, S S; Shvetcov, V S; Skoro, G; Smirnov, N; Snellings, R; Sowinski, J; Spinka, H M; Srivastava, B; Stephenson, E J; Stock, R; Stolpovsky, A; Strikhanov, M; Stringfellow, B; Stroebele, H; Struck, C; Suaide, A A; Sugarbaker, E; Suire, C; Sumbera, M; Symons, T J; 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; Underwood, D G; Van Buren, G; VanderMolen, A M; Vanyashin, A; Vasilevski, I M; Vasiliev, A N; Vigdor, S E; Voloshin, S A; Wang, F; Ward, H; Watson, J W; Wells, R; Wenaus, T; Westfall, G D; Whitten, C; Wieman, 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; Zanevski, Y V; Zborovský, I; Zhang, W M; Zoulkarneev, R; Zubarev, A N

    2001-08-20

    Two-pion correlation functions in Au+Au collisions at square root of [s(NN)] = 130 GeV have been measured by the STAR (solenoidal tracker at RHIC) detector. The source size extracted by fitting the correlations grows with event multiplicity and decreases with transverse momentum. Anomalously large sizes or emission durations, which have been suggested as signals of quark-gluon plasma formation and rehadronization, are not observed. The Hanbury Brown-Twiss parameters display a weak energy dependence over a broad range in square root of [s(NN)]. PMID:11497937

  14. Elliptic flow in Au+Au collisions at square root(S)NN = 130 GeV.

    PubMed

    Ackermann, K H; Adams, N; Adler, C; Ahammed, Z; Ahmad, S; Allgower, C; Amsbaugh, J; Anderson, M; Anderssen, E; Arnesen, H; Arnold, L; Averichev, G S; Baldwin, A; Balewski, J; Barannikova, O; Barnby, L S; Baudot, J; Beddo, M; Bekele, S; Belaga, V V; Bellwied, R; Bennett, S; Bercovitz, J; Berger, J; Betts, W; Bichsel, H; Bieser, F; Bland, L C; Bloomer, M; Blyth, C O; Boehm, J; Bonner, B E; Bonnet, D; Bossingham, R; Botlo, M; Boucham, A; Bouillo, N; Bouvier, S; Bradley, K; Brady, F P; Braithwaite, E S; Braithwaite, W; Brandin, A; Brown, R L; Brugalette, G; Byrd, C; Caines, H; Calderón de la Barca Sánchez, M; Cardenas, A; Carr, L; Carroll, J; Castillo, J; Caylor, B; Cebra, D; Chatopadhyay, S; Chen, M L; Chen, W; Chen, Y; Chernenko, S P; Cherney, M; Chikanian, A; Choi, B; Chrin, J; Christie, W; Coffin, J P; Conin, L; Consiglio, C; Cormier, T M; Cramer, J G; Crawford, H J; Danilov, V I; Dayton, D; DeMello, M; Deng, W S; Derevschikov, A A; Dialinas, M; Diaz, H; DeYoung, P A; Didenko, L; Dimassimo, D; Dioguardi, J; Dominik, W; Drancourt, C; Draper, J E; Dunin, V B; Dunlop, J C; Eckardt, V; Edwards, W R; Efimov, L G; Eggert, T; Emelianov, V; Engelage, J; Eppley, G; Erazmus, B; Etkin, A; Fachini, P; Feliciano, C; Ferenc, D; Ferguson, M I; Fessler, H; Finch, E; Fine, V; Fisyak, Y; Flierl, D; Flores, I; Foley, K J; Fritz, D; Gagunashvili, N; Gans, J; Gazdzicki, M; Germain, M; Geurts, F; Ghazikhanian, V; Gojak, C; Grabski, J; Grachov, O; Grau, M; Greiner, D; Greiner, L; Grigoriev, V; Grosnick, D; Gross, J; Guilloux, G; Gushin, E; Hall, J; Hallman, T J; Hardtke, D; Harper, G; Harris, J W; He, P; Heffner, M; Heppelmann, S; Herston, T; Hill, D; Hippolyte, B; Hirsch, A; Hjort, E; Hoffmann, G W; Horsley, M; Howe, M; Huang, H Z; Humanic, T J; Hümmler, H; Hunt, W; Hunter, J; Igo, G J; Ishihara, A; Ivanshin, Y I; Jacobs, P; Jacobs, W W; Jacobson, S; Jared, R; Jensen, P; Johnson, I; Jones, P G; Judd, E; Kaneta, M; Kaplan, M; Keane, D; Kenney, V P; Khodinov, A; Klay, J; Klein, S R; Klyachko, A; Koehler, G; Konstantinov, A S; Kormilitsyne, V; Kotchenda, L; Kotov, I; Kovalenko, A D; Kramer, M; Kravtsov, P; Krueger, K; Krupien, T; Kuczewski, P; Kuhn, C; Kunde, G J; Kunz, C L; Kutuev, R K; Kuznetsov, A A; Lakehal-Ayat, L; Lamas-Valverde, J; Lamont, M A; Landgraf, J M; Lange, S; Lansdell, C P; Lasiuk, B; Laue, F; Lebedev, A; LeCompte, T; Leonhardt, W J; Leontiev, V M; Leszczynski, P; LeVine, M J; Li, Q; Li, Q; Li, Z; Liaw, C J; Lin, J; Lindenbaum, S J; Lindenstruth, V; Lindstrom, P J; Lisa, M A; Liu, H; Ljubicic, T; Llope, W J; LoCurto, G; Long, H; Longacre, R S; Lopez-Noriega, M; Lopiano, D; Love, W A; Lutz, J R; Lynn, D; Madansky, L; Maier, R; Majka, R; Maliszewski, A; Margetis, S; Marks, K; Marstaller, R; Martin, L; Marx, J; Matis, H S; Matulenko, Y A; Matyushevski, E A; McParland, C; McShane, T S; Meier, J; Melnick, Y; Meschanin, A; Middlekamp, P; Mikhalin, N; Miller, B; Milosevich, Z; Minaev, N G; Minor, B; Mitchell, J; Mogavero, E; Moiseenko, V A; Moltz, D; Moore, C F; Morozov, V; Morse, R; de Moura, M M; Munhoz, M G; Mutchler, G S; Nelson, J M; Nevski, P; Ngo, T; Nguyen, M; Nguyen, T; Nikitin, V A; Nogach, L V; Noggle, T; Norman, B; Nurushev, S B; Nussbaum, T; Nystrand, J; Odyniec, G; Ogawa, A; Ogilvie, C A; Olchanski, K; Oldenburg, M; Olson, D; Ososkov, G A; Ott, G; Padrazo, D; Paic, G; Pandey, S U; Panebratsev, Y; Panitkin, S Y; Pavlinov, A I; Pawlak, T; Pentia, M; Perevotchikov, V; Peryt, W; Petrov, V A; Pinganaud, W; Pirogov, S; Platner, E; Pluta, J; Polk, I; Porile, N; Porter, J; Poskanzer, A M; Potrebenikova, E; Prindle, D; Pruneau, C; Puskar-Pasewicz, J; Rai, G; Rasson, J; Ravel, O; Ray, R L; Razin, S V; Reichhold, D; Reid, J; Renfordt, R E; Retiere, F; Ridiger, A; Riso, J; Ritter, H G; Roberts, J B; Roehrich, D; Rogachevski, O V; Romero, J L; Roy, C; Russ, D; Rykov, V; Sakrejda, I; Sanchez, R; Sandler, Z; Sandweiss, J; Sappenfield, P; Saulys, A C; Savin, I; Schambach, J; Scharenberg, R P; Scheblien, J; Scheetz, R; Schlueter, R; Schmitz, N; Schroeder, L S; Schulz, M; Schüttauf, A; Sedlmeir, J; Seger, J; Seliverstov, D; Seyboth, J; Seyboth, P; Seymour, R; Shakaliev, E I; Shestermanov, K E; Shi, Y;