Sample records for zinc etude des

  1. Etude theorique des fluctuations structurales dans les composes organiques a dimensionnalite reduite

    NASA Astrophysics Data System (ADS)

    Dumoulin, Benoit

    Les systemes a dimensionnalite reduite constituent maintenant une branche entiere de la physique de la matiere condensee. Cette derniere s'est developpee rapidement au cours des dernieres annees, avec la decouverte des materiaux organiques qui presentent, justement, des proprietes physiques fortement anisotropes. Cette these presente une etude en trois parties de plusieurs composes organiques qui, bien que tres differents du point de vue de leurs compositions chimiques et de leurs proprietes physiques a haute temperature, subissent tous une instabilite structurale a tres basse temperature. De plus, dans chacun des cas, l'instabilite structurale est precedee d'un important regime fluctuatif a partir duquel les proprietes physiques changent de maniere significative. Notre etude suit un ordre chronologique inverse puisque nous nous attardons en premier lieu au cas de composes recemment decouverts: les composes de la famille des (BCPTTF)2X (X = PF6 , AsF6). Ces derniers sont des isolants magnetiques a la temperature ambiante et subissent une instabilite structurale de type spin-Peierls a une temperature appelee TSP. En particulier, nous nous interessons a l'etude des proprietes physiques de ces systemes dans le regime fluctuatif, qui precede cette instabilite. Notre etude theorique nous permet de comprendre en detail comment ces systemes s'approchent de l'instabilite struturale. Dans la seconde partie de cette these, nous etudions le regime fluctuatif (pre-transitionnel) observe experimentalement dans le compose de (TMTTF)2PF6. Ce compose organique, dont la structure s'apparente aux sels de Bechgaard, subit une instabilite de type spin-Peierls a une temperature T SP = 19K. Bien que ce compose possede la particularite d'etre un bon conducteur a la temperature ambiante, il subit une transition de type Mott-Hubbard a une temperature Trho ≈ 220K et devient alors un isolant magnetique, analogue aux composes de la famille des (BCPTTF)2X. Le regime fluctuatif precedant l

  2. Etude spectroscopique des collisions moleculaires (hydrogene-azote et hydrogene-oxygene) a des energies de quelques MeV

    NASA Astrophysics Data System (ADS)

    Plante, Jacinthe

    1998-09-01

    Les resultats presentes ici proviennent d'une etude systematique portant sur les collisions a vitesse constante, entre les projectiles d'hydrogene (H+, H2+ et H3+ a 1 MeV/nucleon) et deux cibles gazeuses (N2 et O2), soumises a differentes pressions. Les collisions sont analysees a l'aide des spectres d'emission (de 400 A a 6650 A) et des graphiques intensite/pression. Les spectres ont revele la presence des raies d'azote atomique, d'azote moleculaire, d'oxygene atomique, d'oxygene moleculaire et d'hydrogene atomique. Les raies d'hydrogene sont observees seulement avec les projectiles H2+ et H3+. Donc les processus responsables de la formation de ces raies sont des mecanismes de fragmentation des projectiles. Pour conclure, il existe une difference notable entre les projectiles et les differentes pressions. Les raies d'azote et d'oxygene augmentent selon la pression et les raies d'hydrogene atomique presentent une relation non lineaire avec la pression.

  3. Etude aerodynamique d'un jet turbulent impactant une paroi concave

    NASA Astrophysics Data System (ADS)

    LeBlanc, Benoit

    Etant donne la demande croissante de temperatures elevees dans des chambres de combustion de systemes de propulsions en aerospatiale (turbomoteurs, moteur a reaction, etc.), l'interet dans le refroidissement par jets impactant s'est vu croitre. Le refroidissement des aubes de turbine permet une augmentation de temperature de combustion, ce qui se traduit en une augmentation de l'efficacite de combustion et donc une meilleure economie de carburant. Le transfert de chaleur dans les au bages est influence par les aspects aerodynamiques du refroidissement a jet, particulierement dans le cas d'ecoulements turbulents. Un manque de comprehension de l'aerodynamique a l'interieur de ces espaces confinees peut mener a des changements de transfert thermique qui sont inattendus, ce qui augmente le risque de fluage. Il est donc d'interet pour l'industrie aerospatiale et l'academie de poursuivre la recherche dans l'aerodynamique des jets turbulents impactant les parois courbes. Les jets impactant les surfaces courbes ont deja fait l'objet de nombreuses etudes. Par contre des conditions oscillatoires observees en laboratoire se sont averees difficiles a reproduire en numerique, puisque les structures d'ecoulements impactants des parois concaves sont fortement dependantes de la turbulence et des effets instationnaires. Une etude experimentale fut realisee a l'institut PPRIME a l'Universite de Poitiers afin d'observer le phenomene d'oscillation dans le jet. Une serie d'essais ont verifie les conditions d'ecoulement laminaires et turbulentes, toutefois le cout des essais experimentaux a seulement permis d'avoir un apercu du phenomene global. Une deuxieme serie d'essais fut realisee numeriquement a l'Universite de Moncton avec l'outil OpenFOAM pour des conditions d'ecoulement laminaire et bidimensionnel. Cette etude a donc comme but de poursuivre l'enquete de l'aerodynamique oscillatoire des jets impactant des parois courbes, mais pour un regime d'ecoulement transitoire, turbulent

  4. Etude de la dynamique des porteurs dans des nanofils de silicium par spectroscopie terahertz

    NASA Astrophysics Data System (ADS)

    Beaudoin, Alexandre

    Ce memoire presente une etude des proprietes de conduction electrique et de la dynamique temporelle des porteurs de charges dans des nanofils de silicium sondes par rayonnement terahertz. Les cas de nanofils de silicium non intentionnellement dopes et dopes type n sont compares pour differentes configurations du montage experimental. Les mesures de spectroscopie terahertz en transmission montre qu'il est possible de detecter la presence de dopants dans les nanofils via leur absorption du rayonnement terahertz (˜ 1--12 meV). Les difficultes de modelisation de la transmission d'une impulsion electromagnetique dans un systeme de nanofils sont egalement discutees. La detection differentielle, une modification au systeme de spectroscopie terahertz, est testee et ses performances sont comparees au montage de caracterisation standard. Les instructions et des recommendations pour la mise en place de ce type de mesure sont incluses. Les resultats d'une experience de pompe optique-sonde terahertz sont egalement presentes. Dans cette experience, les porteurs de charge temporairement crees suite a l'absorption de la pompe optique (lambda ˜ 800 nm) dans les nanofils (les photoporteurs) s'ajoutent aux porteurs initialement presents et augmentent done l'absorption du rayonnement terahertz. Premierement, l'anisotropie de l'absorption terahertz et de la pompe optique par les nanofils est demontree. Deuxiemement, le temps de recombinaison des photoporteurs est etudie en fonction du nombre de photoporteurs injectes. Une hypothese expliquant les comportements observes pour les nanofils non-dopes et dopes-n est presentee. Troisiemement, la photoconductivite est extraite pour les nanofils non-dopes et dopes-n sur une plage de 0.5 a 2 THz. Un lissage sur la photoconductivite permet d'estimer le nombre de dopants dans les nanofils dopes-n. Mots-cles: nanofil, silicium, terahertz, conductivite, spectroscopie, photoconductivite.

  5. Etude numerique et experimentale de la reponse vibro-acoustique des structures raidies a des excitations aeriennes et solidiennes

    NASA Astrophysics Data System (ADS)

    Mejdi, Abderrazak

    compte. Les modeles developpes ont permis de conduire plusieurs etudes parametriques sur les proprietes vibro-acoustiques des structures d'avions facilitant ainsi la tache des concepteurs. Dans le cadre de cette these, un article a ete publie dans le Journal of Sound and Vibration et trois autres soumis, respectivement aux Journal of Acoustical Society of America, International Journal of Solid Mechanics et au Journal of Sound and Vibration Mots cles : structures raidies, composites, vibro-acoustique, perte par transmission.

  6. Etude du processus de changement vecu par des familles ayant decide d'adopter volontairement des comportements d'attenuation des changements climatiques

    NASA Astrophysics Data System (ADS)

    Leger, Michel T.

    recension des ecrits sur le changement de comportement en environnement. Nous explorons egalement la famille comme systeme fonctionnel de sorte a mieux comprendre ce contexte d'action environnementale qui est, a notre connaissance, peu etudie. Dans le deuxieme article, nous presentons nos resultats de recherche concernant les facteurs d'influence observes ainsi que les competences manifestees au cours du processus d'adoption de nouveaux comportements environnementaux dans trois familles. Enfin, le troisieme article presente les resultats du cas d'une quatrieme famille ou les membres vivent depuis longtemps des modes de vie ecologique. Dans le cadre d'une demarche d'analyse par theorisation ancree, l'etude de ce cas modele nous a permis d'approfondir les categories conceptuelles identifiees dans le deuxieme article de sorte a produire une modelisation de l'integration de comportements environnementaux dans le contexte de la famille. Les conclusions degagees grace a la recension des ecrits nous ont permis d'identifier les elements qui pourraient influencer l'adoption de comportements environnementaux dans des familles. La recension a aussi permis une meilleure comprehension des divers facteurs qui peuvent affecter l'adoption de comportements environnementaux et, enfin, elle a permis de mieux cerner le phenomene de changement de comportement dans le contexte de la famille consideree comme un systeme. En appliquant un processus d'analyse inductif, a partir de nos donnees qualitatives, les resultats de notre etude multi-cas nous ont indique que deux construits conceptuels semblent influencer l'adoption de comportements environnementaux en famille : 1) les valeurs biospheriques communes au sein de la famille et 2) les competences collectivement mises a profit collectivement durant l'essai de nouveaux comportements environnementaux. Notre modelisation du processus de changement dans des familles indique aussi qu'une dynamique familiale collaborative et la presence d'un groupe de

  7. Etudes optiques de nouveaux materiaux laser: Des orthosilicates dopes a l'ytterbium: Le yttrium (lutetium,scandium) pentoxide de silicium

    NASA Astrophysics Data System (ADS)

    Denoyer, Aurelie

    La decouverte et l'elaboration de nouveaux materiaux laser solides suscitent beaucoup d'interet parmi la communaute scientifique. En particulier les lasers dans la gamme de frequence du micron debouchent sur beaucoup d'applications, en telecommunication, en medecine, dans le domaine militaire, pour la, decoupe des metaux (lasers de puissance), en optique non lineaire (doublage de frequence, bistabilite optique). Le plus couramment utilise actuellement est le Nd:YAG dans cette famille de laser, mais des remplacants plus performants sont toujours recherches. Les lasers a base d'Yb3+ possedent beaucoup d'avantages compares aux lasers Nd3+ du fait de leur structure electronique simple et de leur deterioration moins rapide. Parmi les matrices cristallines pouvant accueillir l'ytterbium, les orthosilicates Yb:Y 2SiO5, Yb:Lu2SiO5 et Yb:Sc2SiO 5 se positionnent tres bien, du fait de leur bonne conductivite thermique et du fort eclatement de leur champ cristallin necessaire a l'elaboration de lasers quasi-3 niveaux. De plus l'etude fine et systematique des proprietes microscopiques de nouveaux materiaux s'avere toujours tres interessante du point de vue de la recherche fondamentale, c'est ainsi que de nouveaux modeles sont concus (par exemple pour le champ cristallin) ou que de nouvelles proprietes inhabituelles sont decouvertes, menant a de nouvelles applications. Ainsi d'autres materiaux dopes a l'ytterbium sont connus pour leurs proprietes de couplage electron-phonon, de couplage magnetique, d'emission cooperative ou encore de bistabilite optique, mais ces proprietes n'ont encore jamais ete mises en evidence dans Yb:Y 2SiO5, Yb:Lu2SiO5 et Yb:Sc2SiO 5. Ainsi, cette these a pour but l'etude des proprietes optiques et des interactions microscopiques dans Yb:Y2SiO 5, Yb:Lu2SiO5 et Yb:Sc2SiO5. Nous utilisons principalement les techniques d'absorption IR et de spectroscopie Raman pour determiner les excitations du champ cristallin et les modes de vibration dans le materiau

  8. Etude de l'influence de la temperature et de l'humidite sur les proprietes mecaniques en traction des fibres de chanvre et de coco

    NASA Astrophysics Data System (ADS)

    Ho Thi, Thu Nga

    L'objectif de cette etude fut d'etablir l'effet de l'humidite et de la temperature sur la resistance en traction et le module elastique des fibres de chanvre et de coco. Deux etudes ont ete realisees afin d'atteindre cet objectif. La premiere vise l'absorption de l'humidite dans ces fibres en exposition dans l'air (de 0%RH a 80%RH) ainsi que l'absorption de l'eau dans ces fibres immergees dans l'eau aux differentes temperatures. La deuxieme consiste a mesurer la resistance en traction et le module elastique de ces fibres sous differentes conditions d'humidite et de temperature. En basant sur les resultats experimentaux obtenus, les methodes semi empiriques et de reseaux de neurones ont ete utilisees pour but de predire les proprietes en traction (resistance et module d'elasticite) des fibres de chanvre et de coco sous l'influence de l'humidite et de la temperature.

  9. Theoretical and Experimental Methods in Hypersonic Flows (Les Methodes Theoriques et Experimentales pour l’Etude Des Ecoulements Hypersoniques)

    DTIC Science & Technology

    1993-04-01

    PROCEEDINGS 514 OELECTE f Theoretical and A U Experimental Methods in A Hypersonic Flows (Les Methodes Th6oriques et Experimentales pour 1’Etude des...nitrogen ent for both equilibrium and non -equilibrium chemistry between the two groups . Both groups state that the boundary makes this mode even more...flowfield on control is also m?,ndatory unstable due to the necessary oblate shape of Hermes. when the experimental rebuilding is clearly poor and

  10. Etude de l'amelioration de la qualite des anodes par la modification des proprietes du brai

    NASA Astrophysics Data System (ADS)

    Bureau, Julie

    'un additif chimique signifie une possible amelioration de l'interaction entre le coke et le brai modifie. Afin de completer l'evaluation des donnees recueillies, les resultats de la FTIR et de la mouillabilite sont analyses par le reseau neuronal artificiel afin de mieux comprendre les mecanismes sous-jacents. A la lumiere des resultats obtenus, les additifs chimiques les plus prometteurs sont selectionnes afin de verifier l'effet de leur utilisation sur la qualite des anodes. Pour ce faire, des anodes de laboratoire sont produites en utilisant des brais non modifies et des brais modifies avec les additifs chimiques selectionnes. Par la suite, les anodes sont carottees afin de les caracteriser en determinant certaines de leurs proprietes physiques et chimiques. Enfin, les resultats des echantillons d'anodes faites d'un meme brai non modifie et modifie sont compares afin d'evaluer l'amelioration de la qualite des anodes. Finalement, un examen de l'impact possible de l'utilisation d'un additif chimique pour modifier le brai sur la consommation energetique et en carbone ainsi que la quantite d'aluminium produit est realise. Afin de modifier le brai, trois differents additifs chimiques sont selectionnes, soit un tensioactif et deux agents de modification de surface. L'analyse FTIR des experimentations menees sur les brais modifies demontre que deux additifs ont modifie la composition chimique des brais experimentes. L'analyse des resultats des tests goutte-sessile laisse supposer qu'un brai modifie par ces deux additifs ameliore possiblement l'interaction avec les cokes employes dans cette etude. L'analyse par reseau neuronal artificiel des donnees recueillies permet de mieux comprendre le lien entre la composition chimique d'un brai et sa capacite de mouillabilite avec un coke. La caracterisation des echantillons d'anodes produites permet d'affirmer que ces deux additifs peuvent ameliorer certaines des proprietes anodiques comparativement aux echantillons standards. L

  11. Etude experimentale des excitations topologiques de l'effet Hall quantique a nu = 1 dans les heterostructures semiconductrices a double puits quantique

    NASA Astrophysics Data System (ADS)

    Charlebois, Serge

    De nombreux travaux theoriques et experimentaux ont ete publies sur les excitations topologiques de gaz electroniques bidimensionnels (GE2D), appellees skyrmions, dans le regime de l'effet Hall quantique a remplissage unitaire. On attend des excitations semblables appellees bimerons dans les systemes formes de deux GE2D couples. Contrairement au cas des GE2D simples, aucune experience n'a, a notre connaissance, presente la mesure d'une propriete specifique aux bimerons. Nous presentons dans cette these des travaux experimentaux ayant pour objectif l'etude d'excitations topologiques dans les heterostructures a double puits quantique. Une manifestation attendue (les bimerons est la presence d'une anisotropie dans la conductivite a travers une constriction. Nous avons concu un dispositif original a point de contact a trois grilles non-coplanaires. Ce dispositif a trois grilles a la particularite de permettre la creation d'une constriction etroite dans le double GE2D tout en permettant l'equilibrage de la densite electronique entre les deux puits dans l'etroit canal de conduction. Nous avons fabrique ce dispositif de taille submicronique par electrolithographie sur des heterostructures a double puits. Les dispositifs ainsi fabriques ont ete etudies a basse temperature (0.3K) et ont montre un fonctionnement conforme aux attentes. Les travaux n'ont pas permis de mettre en evidence une anisotropie de transport revelatrice de l'existence de bimerons. Cette these est a notre connaissance la premiere etude experimentale visant la realisation de l'experience d'anisotropie de transport et est ainsi une contribution significative a l'avancement des connaissances dans ce domaine. Les travaux theoriques que nous presentons ont permis de montrer l'effet des excitations topologiques sur la capacite grille-GE2D du systeme. Ces travaux ouvrent la voie de la detection des bimerons par l'intermediaire de la mesure de la capacite grille-GE2D ou encore de la susceptibilite electrique du

  12. Etude des phenomenes dynamiques ultrarapides et des caracteristiques impulsionnelles d'emission terahertz du supraconducteur YBCO

    NASA Astrophysics Data System (ADS)

    Savard, Stephane

    Les premieres etudes d'antennes a base de supraconducteurs a haute temperature critique emettant une impulsion electromagnetique dont le contenu en frequence se situe dans le domaine terahertz remontent a 1996. Une antenne supraconductrice est formee d'un micro-pont d'une couche mince supraconductrice sur lequel un courant continu est applique. Un faisceau laser dans le visible est focalise sur le micro-pont et place le supraconducteur dans un etat hors-equilibre ou des paires sont brisees. Grace a la relaxation des quasiparticules en surplus et eventuellement de la reformation des paires supraconductrices, nous pouvons etudier la nature de la supraconductivite. L'analyse de la cinetique temporelle du champ electromagnetique emis par une telle antenne terahertz supraconductrice s'est averee utile pour decrire qualitativement les caracteristiques de celle-ci en fonction des parametres d'operation tels que le courant applique, la temperature et la puissance d'excitation. La comprehension de l'etat hors-equilibre est la cle pour comprendre le fonctionnement des antennes terahertz supraconductrices a haute temperature critique. Dans le but de comprendre ultimement cet etat hors-equilibre, nous avions besoin d'une methode et d'un modele pour extraire de facon plus systematique les proprietes intrinseques du materiau qui compose l'antenne terahertz a partir des caracteristiques d'emission de celle-ci. Nous avons developpe une procedure pour calibrer le spectrometre dans le domaine temporel en utilisant des antennes terahertz de GaAs bombarde aux protons H+ comme emetteur et detecteur. Une fois le montage calibre, nous y avons insere une antenne emettrice dipolaire de YBa 2Cu3O7-delta . Un modele avec des fonctions exponentielles de montee et de descente du signal est utilise pour lisser le spectre du champ electromagnetique de l'antenne de YBa 2Cu3O7-delta, ce qui nous permet d'extraire les proprietes intrinseques de ce dernier. Pour confirmer la validite du modele

  13. Etude hyperfrequence et ultrasonore des supraconducteurs organiques kappa-(ET)(2)X (X = copper(thiocyanogen), copper[N(CN)(2)]bromine)

    NASA Astrophysics Data System (ADS)

    Frikach, Kamal

    2001-09-01

    Dans ce travail je presente une etude de l'impedance de surface, ainsi que de l'attenuation et la variation de la vitesse ultrasonores dans les etats normal et supraconducteur sur les composes organiques k-(ET)2X (X = Cu(SCN) 2, Cu[N(CN)2]Br). A partir des mesures d'impedance de surface, les deux composantes sigma 1 et sigma2 de la conductivite complexe sont extraites en utilisant le modele de Drude. Ces mesures montrent que la symetrie du parametre d'ordre dans ces composes est differente de celle du cas BCS. Afin de comprendre le profil de sigma1 (T) nous avons etudie les fluctuations supraconductrices a partir de la paraconductivite sigma'( T). Cette etude est rendue possible grace a la structure quasi-2D des composes k-(ET)2X dans lesquelles les fluctuations supraconductrices sont fortes. Ces dernieres sont observees sur deux decades de temperatures dans le Cu(SCN)2. L'application du modele de Aslamazov-Larkin 2D et 3D montre la possibilite du passage du regime 2D a haute temperature au regime 3D au voisinage de Tc. En se basant sur ce resultat, nous avons calcule la paraconductivite en utilisant une approche a l'ordre d'une boucle a partir du modele de Lawrence-Doniach. En tenant compte de la correction par la self energie dans la limite dynamique (17 GHz), l'ajustement de la paraconductivite calculee est en bon accord avec les donnees experimentales. Le couplage interplan obtenu est compatible avec le caractere quasi-2D des composes organiques. Le temps de relaxation des quasi-particules dans l'etat supraconducteur est ensuite extrait pour la premiere fois dans ces composes dont le comportement en fonction de la temperature est compatible avec la presence des noeuds dans le gap. Dans l'etat normal, la variation de la vitesse ultrasonore presente un comportement anormal caracterise par un fort ramollissement a T = 38 K et 50 K dans k-(ET) 2Cu(SCN)2 et k-(ET)2Cu[N(CN) 2]Br respectivement dont l'amplitude est independante du champ magnetique jusqu'a H = Hc 2

  14. Impact de la preparation des anodes crues et des conditions de cuisson sur la fissuration dans des anodes denses

    NASA Astrophysics Data System (ADS)

    Amrani, Salah

    La fabrication de l'aluminium est realisee dans une cellule d'electrolyse, et cette operation utilise des anodes en carbone. L'evaluation de la qualite de ces anodes reste indispensable avant leur utilisation. La presence des fissures dans les anodes provoque une perturbation du procede l'electrolyse et une diminution de sa performance. Ce projet a ete entrepris pour determiner l'impact des differents parametres de procedes de fabrication des anodes sur la fissuration des anodes denses. Ces parametres incluent ceux de la fabrication des anodes crues, des proprietes des matieres premieres et de la cuisson. Une recherche bibliographique a ete effectuee sur tous les aspects de la fissuration des anodes en carbone pour compiler les travaux anterieurs. Une methodologie detaillee a ete mise au point pour faciliter le deroulement des travaux et atteindre les objectifs vises. La majorite de ce document est reservee pour la discussion des resultats obtenus au laboratoire de l'UQAC et au niveau industriel. Concernant les etudes realisees a l'UQAC, une partie des travaux experimentaux est reservee a la recherche des differents mecanismes de fissuration dans les anodes denses utilisees dans l'industrie d'aluminium. L'approche etait d'abord basee sur la caracterisation qualitative du mecanisme de la fissuration en surface et en profondeur. Puis, une caracterisation quantitative a ete realisee pour la determination de la distribution de la largeur de la fissure sur toute sa longueur, ainsi que le pourcentage de sa surface par rapport a la surface totale de l'echantillon. Cette etude a ete realisee par le biais de la technique d'analyse d'image utilisee pour caracteriser la fissuration d'un echantillon d'anode cuite. L'analyse surfacique et en profondeur de cet echantillon a permis de voir clairement la formation des fissures sur une grande partie de la surface analysee. L'autre partie des travaux est basee sur la caracterisation des defauts dans des echantillons d'anodes crues

  15. Etude de la performance des radars hautes-frequences CODAR et WERA pour la mesure des courants marins en presence partielle de glace de mer

    NASA Astrophysics Data System (ADS)

    Kamli, Emna

    Les radars hautes-frequences (RHF) mesurent les courants marins de surface avec une portee pouvant atteindre 200 kilometres et une resolution de l'ordre du kilometre. Cette etude a pour but de caracteriser la performance des RHF, en terme de couverture spatiale, pour la mesure des courants de surface en presence partielle de glace de mer. Pour ce faire, les mesures des courants de deux radars de type CODAR sur la rive sud de l'estuaire maritime du Saint-Laurent, et d'un radar de type WERA sur la rive nord, prises pendant l'hiver 2013, ont ete utilisees. Dans un premier temps, l'aire moyenne journaliere de la zone ou les courants sont mesures par chaque radar a ete comparee a l'energie des vagues de Bragg calculee a partir des donnees brutes d'acceleration fournies par une bouee mouillee dans la zone couverte par les radars. La couverture des CODARs est dependante de la densite d'energie de Bragg, alors que la couverture du WERA y est pratiquement insensible. Un modele de fetch appele GENER a ete force par la vitesse du vent predite par le modele GEM d'Environnement Canada pour estimer la hauteur significative ainsi que la periode modale des vagues. A partir de ces parametres, la densite d'energie des vagues de Bragg a ete evaluee pendant l'hiver a l'aide du spectre theorique de Bretschneider. Ces resultats permettent d'etablir la couverture normale de chaque radar en absence de glace de mer. La concentration de glace de mer, predite par le systeme canadien operationnel de prevision glace-ocean, a ete moyennee sur les differents fetchs du vent selon la direction moyenne journaliere des vagues predites par GENER. Dans un deuxieme temps, la relation entre le ratio des couvertures journalieres obtenues pendant l'hiver 2013 et des couvertures normales de chaque radar d'une part, et la concentration moyenne journaliere de glace de mer d'autre part, a ete etablie. Le ratio des couvertures decroit avec l'augmentation de la concentration de glace de mer pour les deux types

  16. Etude de faisabilite d'un systeme eolien diesel avec stockage d'air comprime

    NASA Astrophysics Data System (ADS)

    Benchaabane, Youssef

    Le Systeme Hybride Eolien-Diesel avec Stockage d'Air Comprime (SHEDAC) utilise l'hybridation pneumatique pour remplacer la consommation des combustibles fossiles par de l'energie renouvelable, plus particulierement de l'energie eolienne. Le surplus de l'energie eolienne est utilise pour comprimer et stocker de l'air qui est utilise ensuite pour suralimenter le moteur diesel. Le memoire de maitrise est constitue de deux articles scientifiques. Le premier article presente le developpement d'un logiciel dedie a l'etude de faisabilite d'un systeme eolien-diesel avec stockage d'air comprime. Cette etude est basee sur l'analyse des couts et des revenus, des couts des equipements (eolienne, moteur diesel, systeme de stockage d'air). Elle est completee par une analyse de sensibilite aux differents parametres, une analyse des risques et des emissions des gaz a effet de serre (GES). Le deuxieme article est une application de ce logiciel pour l'installation d'un systeme SHEDAC au camp minier Esker au Quebec en remplacement des sources actuelles de production d'energie. L'utilisation du stockage d'air comprime a l'aide d'un systeme SHEDAC est le plus rentable par rapport a l'utilisation de l'energie eolienne seule ou d'une centrale thermique au diesel seule ou des deux combinees. Avec une valeur actuelle nette et un taux de rendement interne plus eleves, cette solution permet d'obtenir le plus bas cout de l'energie pour cette region eloignee. None None None

  17. Synthese, etude structurale et electrochimique des materiaux d'electrode positive d'oxydes mixtes lithium cobalt nickel oxide (0 /= 1) pour les batteries rechargeables au lithium

    NASA Astrophysics Data System (ADS)

    Grincourt, Yves

    Depuis une dizaine d'annees, on observe un interet grandissant pour les batteries rechargeables au lithium de tension superieure a 4 volts. La commercialisation de ces batteries pour l'electronique grand marche tend de plus en plus a supplanter celle des accumulateurs Ni-Cd et Ni-MH, de tension nominate 1,2 V. Ces batteries au lithium font appel a des materiaux d'electrode positive (cathode a la decharge) du type oxydes mixtes de metaux de transition LiMnO 2, LiMn2O4, LiNiO2 ou LiCoO2. Si le compose LiCoO2 est relativement aise a synthetiser, il n'en demeure pas moins que le cobalt reste un metal plus couteux compare au nickel et au manganese. La synthese de LiNiO2, quart a elle, demeure un probleme du point de vue stoechiometrique. Un defaut de lithium (5 a 10% molaire) conduira a des proprietes electrochimiques mediocres de la batterie. Dans cette etude nous nous proposons donc de preparer par voie humide et par voie seche les materiaux d'electrode positive de la famille LiCoyNi1-yO2 aver (0 ≤ y ≤ 1) et d'etudier en detail l'influence du pourcentage de nickel et de cobalt sur les proprietes electrochimiques des oxydes mixtes Li-Ni-Co. Une des caracteristiques est la morphologie plus fine des poudres de materiaux, observes par microscopie electronique a balayage (MEB). Un traitement thermique a plus basse temperature (750°C) que pour LiCoO2 (850°C) ainsi qu'un leger exces de lithium dans la preparation, ont permis d'aboutir a un materiau de stoechiometrie quasi parfaite. Neanmoins, le role de pilfer joue par 2 a 4% de moles de Ni2+ presents sur les sites lithium, permet de conserver intacte la structure hexagonale de la maille entre deux cycles consecutifs. Afin de mieux comprendre l'influence du vieillissement dune demi-pile Li/LiMeO2 (Me = Ni, Co) a temperature ambiante, des etudes electrochimiques et d'impedance spectroscopique ont ete menees en parallele. Le vieillissement de la cellule s'accompagne seulement dune chute de son potentiel due a son auto

  18. Etude exploratoire des conceptions de la circulation sanguine aupres d'eleves de l'ordre collegial

    NASA Astrophysics Data System (ADS)

    Robitaille, Jean-Marc

    Il existe peu d'etudes sur les conceptions touchant les domaines de la biologie, notamment sur les conceptions de la circulation sanguine Nous avons observe egalement l'absence de recherche menee aupres d'eleves de l'ordre collegial sur cette question. Nous avons voulu combler une lacune en menant une recherche sur les conceptions de la circulation sanguine aupres d'eleves de l'ordre collegial. Pour mener cette recherche nous nous sommes inspires d'une methode developpee par Treagust (1988). Le premier niveau de formulation didactique etablit l'architecture du systeme et la fonction nutritive de la circulation. Le second niveau de formulation didactique decrit et relie les parametres de la dynamique de la circulation et leur relation: Pression, Debit et Resistance. Le troisieme niveau de formulation didactique s'interesse au controle de la circulation du sang dans un contexte d'homeostasie qui implique la regulation de la pression arterielle. Nous avons construit un questionnaire en nous guidant sur les niveaux de formulation didactique et l'analyse des entrevues menees aupres de dix-huit eleves, representatifs de la population cible. Ce questionnaire fut administre a un echantillon de 2300 eleves disperses dans six colleges de la region de Montreal. Notre echantillon comprend des eleves inscrits a des programmes de l'ordre collegial en Sciences de la nature et en Techniques de la sante et qui n'ont pas suivi le cours sur la circulation sanguine. Notre analyse des reponses des eleves de notre echantillon aux questions sur le premier niveau de formulation didactique revele que la majorite des eleves considerent que le systeme circulatoire relie les organes les uns aux autres dans un circuit en serie. Notre analyse revele egalement que la majorite des eleves estiment que les nutriments sont extraits du sang par les organes selon un processus de selection base sur les besoins determines par la fonction de l'organe. Ces besoins sont differents selon les organes qui ne

  19. Les effets des interfaces sur les proprietes magnetiques et de transport des multicouches nickel/iron et cobalt/silver

    NASA Astrophysics Data System (ADS)

    Veres, Teodor

    Cette these est consacree a l'etude de l'evolution structurale des proprietes magnetiques et de transport des multicouches Ni/Fe et nanostructures a base de Co et de l'Ag. Dans une premiere partie, essentiellement bibliographique, nous introduisons quelques concepts de base relies aux proprietes magnetiques et de transport des multicouches metalliques. Ensuite, nous presentons une breve description des methodes d'analyse des resultats. La deuxieme partie est consacree a l'etude des proprietes magnetiques et de transport des multicouches ferromagnetiques/ferromagnetiques Ni/Fe. Nous montrerons qu'une interpretation coherente de ces proprietes necessite la prise en consideration des effets des interfaces. Nous nous attacherons a mettre en evidence, a evaluer et a etudier les effets de ces interfaces ainsi que leur evolution, et ce, suite a des traitements thermiques tel que le depot a temperature elevee et l'irradiation ionique. Les analyses correlees de la structure et de la magnetoresistance nous permettront d'emettre des conclusions sur l'influence des couches tampons entre l'interface et le substrat ainsi qu'entre les couches elles-memes sur le comportement magnetique des couches F/F. La troisieme partie est consacree aux systemes a Magneto-Resistance Geante (MRG) a base de Co et Ag. Nous allons etudier l'evolution de la microstructure suite a l'irradiation avec des ions Si+ ayant une energie de 1 MeV, ainsi que les effets de ces changements sur le comportement magnetique. Cette partie debutera par l'analyse des proprietes d'une multicouche hybride, intermediaire entre les multicouches et les materiaux granulaires. Nous analyserons a l'aide des mesures de diffraction, de relaxation superparamagnetique et de magnetoresistance, les evolutions structurales produites par l'irradiation ionique. Nous etablirons des modeles qui nous aideront a interpreter les resultats pour une serie des multicouches qui couvrent un large eventail de differents comportements magnetiques

  20. Problemes en enseignement fonctionnel des langues (Problems in the Functional Teaching of Languages). Publication B-103.

    ERIC Educational Resources Information Center

    Alvarez, Gerardo, Ed.; Huot, Diane, Ed.

    Articles include: (1) "L'elaboration du materiel pedagogique pour des publics adultes" (The Elaboration of Teaching Materials for the Adult Public) by G. Painchaud-Leblanc, (2) "L'elaboration d'un programme d'etudes en francais langue seconde a partir des donnees recentes en didactique des langues" (The Elaboration of a Program…

  1. Elaboration de revetements nanocomposites avec des proprietes superhydrophobes, semi-conductrices et photocatalytiques

    NASA Astrophysics Data System (ADS)

    Madidi, Fatima Zahra

    Les lignes aeriennes de transport et de distribution de l'energie electrique sont souvent exposees a diverses contraintes. Parmi celles-ci, la pollution des isolateurs constitue l'un des facteurs de premiere importance dans la fiabilite du transport d'energie. En effet, la presence de pollution sur les isolateurs lorsqu'elle est humidifiee entraine la diminution de leur performance electrique en favorisant l'apparition d'arcs de contournement. De telles pannes peuvent parfois causer des impacts socioeconomiques importants. Par ailleurs, le developpement de nouveaux revetements pour ces isolateurs peut s'averer un moyen efficace pour les proteger contre l'apparition de l'arc de contournement. Les revetements superhydrophobes ont fait l'objet de nombreuses etudes au cours de ces dernieres annees. Ces surfaces sont preparees en combinant une rugosite nano-microstructuree avec une faible energie de surface. En outre, de telles surfaces ont de nombreuses applications si elles sont durables et n'ont pas d'effets nocifs sur l'environnement. L'objectif principal de la presente etude vise d'abord l'elaboration de revetements superhydrophobes, puis l'etude de leur duree de vie, leurs proprietes dielectriques et photocatalytiques. Une grande variete de materiaux a faible energie de surface peuvent etre utilises pour le developpement de ces revetements. Dans cette recherche, le caoutchouc de silicone (CS) est employe car il presente de nombreuses proprietes, notamment une forte hydrophobie, une resistance aux rayonnements ultraviolets, et une bonne tenue au feu sans degagement de produits toxiques. Toutefois, le point faible de ces materiaux est la degradation de leurs proprietes hydrophobes. Afin d'ameliorer certaines proprietes du caoutchouc de silicone, des nanoparticules seront additionnees au polymere de base. La technique d'elaboration des revetements consiste a ajouter des nanoparticules de dioxyde de titane (TiO2) au polymere de base, par des methodes ayant un

  2. Gestion des ressources hydriques adaptee aux changements climatiques pour la production optimale d'hydroelectricite. Etude de cas: Bassin versant de la riviere Manicouagan

    NASA Astrophysics Data System (ADS)

    Haguma, Didier

    Il est dorenavant etabli que les changements climatiques auront des repercussions sur les ressources en eau. La situation est preoccupante pour le secteur de production d'energie hydroelectrique, car l'eau constitue le moteur pour generer cette forme d'energie. Il sera important d'adapter les regles de gestion et/ou les installations des systemes hydriques, afin de minimiser les impacts negatifs et/ou pour capitaliser sur les retombees positives que les changements climatiques pourront apporter. Les travaux de la presente recherche s'interessent au developpement d'une methode de gestion des systemes hydriques qui tient compte des projections climatiques pour mieux anticiper les impacts de l'evolution du climat sur la production d'hydroelectricite et d'etablir des strategies d'adaptation aux changements climatiques. Le domaine d'etude est le bassin versant de la riviere Manicouagan situe dans la partie centrale du Quebec. Une nouvelle approche d'optimisation des ressources hydriques dans le contexte des changements climatiques est proposee. L'approche traite le probleme de la saisonnalite et de la non-stationnarite du climat d'une maniere explicite pour representer l'incertitude rattachee a un ensemble des projections climatiques. Cette approche permet d'integrer les projections climatiques dans le probleme d'optimisation des ressources en eau pour une gestion a long terme des systemes hydriques et de developper des strategies d'adaptation de ces systemes aux changements climatiques. Les resultats montrent que les impacts des changements climatiques sur le regime hydrologique du bassin de la riviere Manicouagan seraient le devancement et l'attenuation de la crue printaniere et l'augmentation du volume annuel d'apports. L'adaptation des regles de gestion du systeme hydrique engendrerait une hausse de la production hydroelectrique. Neanmoins, une perte de la performance des installations existantes du systeme hydrique serait observee a cause de l'augmentation des

  3. Caracterisation des proprietes dielectriques de materiaux composites a base de polyethylene terephtalate recycle =

    NASA Astrophysics Data System (ADS)

    Mebarki, Fouzia

    Cette etude vise a etudier la possibilite d'utiliser des materiaux composites a matrice thermoplastique pour des applications electriques comme les supports des systemes d'allumage dans les moteurs d'automobile. Nous nous interessons plus particulierement aux composites a base de polyethylene terephtalate (PET) recycle. Les isolants classiques comme le PET ne peuvent pas satisfaire toutes les exigences. L'introduction des renforts comme les fibres de verre et le mica peuvent ameliorer les caracteristiques mecaniques de ces materiaux. Toutefois, cette amelioration peut etre accompagnee d'une diminution des proprietes electriques surtout que ces materiaux doivent operer sous contraintes thermiques et electriques tres severes. Afin d'estimer la duree de vie de ces isolants, des essais de vieillissement accelere ont ete effectues a une frequence de 300Hz dans une plage de temperature allant de la temperature ambiante a 140°C. L'etude a haute temperature permettra de determiner la temperature de service des materiaux candidats. Des essais de la rupture dielectrique ont ete realises sur un grand nombre d'echantillon selon la norme ASTM D-149 relative aux mesures de rigidite dielectrique des isolants solides. Ces tests ont permis de deceler les echantillons problematiques et de verifier la qualite de ces isolants solides. Les differentes connaissances acquises lors de cette analyse ont servi a predire les performances des materiaux en service et vont permettre a la compagnie Groupe Lavergne d'apporter des ameliorations au niveau des formulations existantes et par la suite developper un materiau ayant les proprietes electriques et thermiques adequates pour ce type d'application. None None None None

  4. De l'importance des orbites periodiques: Detection et applications

    NASA Astrophysics Data System (ADS)

    Doyon, Bernard

    L'ensemble des Orbites Periodiques Instables (OPIs) d'un systeme chaotique est intimement relie a ses proprietes dynamiques. A partir de l'ensemble (en principe infini) d'OPIs cachees dans l'espace des phases, on peut obtenir des quantites dynamiques importantes telles les exposants de Lyapunov, la mesure invariante, l'entropie topologique et la dimension fractale. En chaos quantique (i.e. l'etude de systemes quantiques qui ont un equivalent chaotique dans la limite classique), ces memes OPIs permettent de faire le pont entre le comportement classique et quantique de systemes non-integrables. La localisation de ces cycles fondamentaux est un probleme complexe. Cette these aborde dans un premier temps le probleme de la detection des OPIs dans les systemes chaotiques. Une etude comparative de deux algorithmes recents est presentee. Nous approfondissons ces deux methodes afin de les utiliser sur differents systemes dont des flots continus dissipatifs et conservatifs. Une analyse du taux de convergence des algorithmes est aussi realisee afin de degager les forces et les limites de ces schemes numeriques. Les methodes de detection que nous utilisons reposent sur une transformation particuliere de la dynamique initiale. Cette astuce nous a inspire une methode alternative pour cibler et stabiliser une orbite periodique quelconque dans un systeme chaotique. Le ciblage est en general combine aux methodes de controle pour stabiliser rapidement un cycle donne. En general, il faut connaitre la position et la stabilite du cycle en question. La nouvelle methode de ciblage que nous presentons ne demande pas de connaitre a priori la position et la stabilite des orbites periodiques. Elle pourrait etre un outil complementaire aux methodes de ciblage et de controle actuelles.

  5. Effets des electrons secondaires sur l'ADN

    NASA Astrophysics Data System (ADS)

    Boudaiffa, Badia

    Les interactions des electrons de basse energie (EBE) representent un element important en sciences des radiations, particulierement, les sequences se produisant immediatement apres l'interaction de la radiation ionisante avec le milieu biologique. Il est bien connu que lorsque ces radiations deposent leur energie dans la cellule, elles produisent un grand nombre d'electrons secondaires (4 x 104/MeV), qui sont crees le long de la trace avec des energies cinetiques initiales bien inferieures a 20 eV. Cependant, il n'y a jamais eu de mesures directes demontrant l'interaction de ces electrons de tres basse energie avec l'ADN, du principalement aux difficultes experimentales imposees par la complexite du milieu biologique. Dans notre laboratoire, les dernieres annees ont ete consacrees a l'etude des phenomenes fondamentaux induits par impact des EBE sur differentes molecules simples (e.g., N2, CO, O2, H2O, NO, C2H 4, C6H6, C2H12) et quelques molecules complexes dans leur phase solide. D'autres travaux effectues recemment sur des bases de l'ADN et des oligonucleotides ont montre que les EBE produisent des bris moleculaires sur les biomolecules. Ces travaux nous ont permis d'elaborer des techniques pour mettre en evidence et comprendre les interactions fondamentales des EBE avec des molecules d'interet biologique, afin d'atteindre notre objectif majeur d'etudier l'effet direct de ces particules sur la molecule d'ADN. Les techniques de sciences des surfaces developpees et utilisees dans les etudes precitees peuvent etre etendues et combinees avec des methodes classiques de biologie pour etudier les dommages de l'ADN induits par l'impact des EBE. Nos experiences ont montre l'efficacite des electrons de 3--20 eV a induire des coupures simple et double brins dans l'ADN. Pour des energies inferieures a 15 eV, ces coupures sont induites par la localisation temporaire d'un electron sur une unite moleculaire de l'ADN, ce qui engendre la formation d'un ion negatif transitoire

  6. Education relative a l'environnement (ERE): Une etude des representations sociales et des pratiques educatives d'enseignants de science et technologie du secondaire en contexte de formation continue

    NASA Astrophysics Data System (ADS)

    Collard-Fortin, Ugo

    Le developpement des sciences/technologie a tres clairement contribue a ce que ce dernier domaine de savoirs jouisse d'une place de choix au sein de notre societe. Au-dela des progres de notre civilisation inherents a ce dernier developpement, cette croissance amena avec elle un lot d'ineluctables dommages collateraux, contribuant en corollaire a l'emergence de diverses problematiques environnementales inquietantes pour lesquelles les valeurs ainsi que le mode de fonctionnement de la societe occidentale contemporaine sont largement tributaires. C'est entre autres en reponse a cet etat de fait que la recente vague de reforme de l'Education conduisit a l'integration, dans les curricula de sciences/technologie, de contenus relavant d'education relative a l'environnement (ERE). Face au changement, les enseignants de sciences ont du s'approprier ce nouveau programme afm de l'enseigner a leurs eleves. Toutefois, l'analyse de la situation montre que les prescriptions du programme en matiere d'ERE ne se sont pas toujours traduites en de reelles actions dans la pratique. Le contexte de notre etude s'est interesse aux pratiques educatives de l'ERE ainsi qu'a la representation sociale qui en decoule. Notre recherche aborde plus specifiquement la problematique de la modification de ces derniers objets chez les enseignants de sciences et technologie du deuxieme cycle du secondaire. Pour y arriver, nous avons propose a un groupe de trois praticiens de participer a une activite, en communaute de pratique, de formation continue orientee autour de thematiques ERE. Cette recherche developpement, s'inscrivant dans un paradigme qualitatif/interpretatif, s'est appuyee sur une cueillette de donnees effectuee a partir d'entrevues semi-dirigees, d'observations en situation et d'un groupe de discussion, au debut et a la fm de la formation continue. Les donnees brutes ont ete soumises a une demarche d'analyse inductive et ont genere diverses categories etayant nos objets de recherche

  7. Etudes physiques des mélanges eau-cryoprotecteurs

    NASA Astrophysics Data System (ADS)

    Vassoille, R.; Perez, J.

    The aim of the following review is to present the most important studies concerning the physical properties of water-solutes mixtures used in cryobiology. Cryobiology is a branch of biology which deals with the very low temperature behaviour of cells. This technique is developed today in several directions. The creation of banks of cells and perhaps in a short time of small organs, is the purpose of much research in this domain. Before freezing, living cells are generally put in a solution containing one or more solutes. The role of these solutes is to protect the cells against damage due to crystallization of water (cryoprotectors). The mechanisms of cryoprotection are not well known ; nevertheless the vitreous state formation during cooling is often invoked. So, it is possible to avoid crystallization damage such as mechanical strain (due to an increase of volume of about 10 %) and salt effects (due to osmotic pressure). The conditions in which the vitreous state is obtained, maintained during cooling, storage at low temperature and rewarming can be defined by physical studies presented in the following review. Le présent travail est essentiellement une revue bibliographique des principales études physiques qui ont été réalisées avec des solutions de composés habituellement employés en cryobiologie. La cryobiologie est une branche de la biologie qui s'intéresse au comportement des cellules à basse température. Cette discipline est actuellement en plein développement dans des domaines très divers. Son principal but est la création de banques de cellules de plus en plus complexes avec comme perspective la conservation des organes. Les cellules vivantes sont généralement placées avant congélation dans une solution contenant divers composés dont le rôle est de protéger les cellules contre les effets de la cristallisation de l'eau. L'action protectrice de ces cryoprotecteurs est encore mal connue; cependant, la formation d'un état vitreux lors du

  8. Etude vibroacoustique d'un systeme coque-plancher-cavite avec application a un fuselage simplifie

    NASA Astrophysics Data System (ADS)

    Missaoui, Jemai

    L'objectif de ce travail est de developper des modeles semi-analytiques pour etudier le comportement structural, acoustique et vibro-acoustique d'un systeme coque-plancher-cavite. La connection entre la coque et le plancher est assuree en utilisant le concept de rigidite artificielle. Ce concept de modelisation flexible facilite le choix des fonctions de decomposition du mouvement de chaque sous-structure. Les resultats issus de cette etude vont permettre la comprehension des phenomenes physiques de base rencontres dans une structure d'avion. Une approche integro-modale est developpee pour calculer les caracteristiques modales acoustiques. Elle utilise une discretisation de la cavite irreguliere en sous-cavites acoustiques dont les bases de developpement sont connues a priori. Cette approche, a caractere physique, presente l'avantage d'etre efficace et precise. La validite de celle-ci a ete demontree en utilisant des resultats disponibles dans la litterature. Un modele vibro-acoustique est developpe dans un but d'analyser et de comprendre les effets structuraux et acoustiques du plancher dans la configuration. La validite des resultats, en termes de resonance et de fonction de transfert, est verifiee a l'aide des mesures experimentales realisees au laboratoire.

  9. Transport de paires EPR dans des structures mesoscopiques

    NASA Astrophysics Data System (ADS)

    Dupont, Emilie

    Dans cette these, nous nous sommes particulierement interesses a la propagation de paires EPR1 delocalisees et localisees, et a l'influence d'un supraconducteur sur le transport de ces paires. Apres une introduction de cette etude, ainsi que du cadre scientifique qu'est l'informatique quantique dans lequel elle s'inscrit, nous allons dans le chapitre 1 faire un rappel sur le systeme constitue de deux points quantiques normaux entoures de deux fils supraconducteurs. Cela nous permettra d'introduire une methode de calcul qui sera reutilisee par la suite, et de trouver egalement le courant Josephson produit par ce systeme transforme en SQUID-dc par l'ajout d'une jonction auxiliaire. Le SQUID permet de mesurer l'etat de spin (singulet ou triplet), et peut etre forme a partir d'autres systemes que nous etudierons ensuite. Dans le chapitre 2, nous rappellerons l'etude detaillee d'un intricateur d'Andreev faite par un groupe de Bale. La matrice T, permettant d'obtenir le courant dans les cas ou les electrons sont separes spatialement ou non, sera etudiee en detail afin d'en faire usage au chapitre suivant. Le chapitre 3 est consacre a l'etude de l'influence du bruit sur le fonctionnement de l'intricateur d'Andreev. Ce bruit modifie la forme du courant jusqu'a aboutir a d'autres conditions de fonctionnement de l'intricateur. En effet, le bruit present sur les points quantiques peut perturber le transport des paires EPR par l'intermediaire des degres de liberte. Nous montrerons que, du fait de l'"intrication" entre la charge de la paire et le bruit, la paire est detruite pour des temps longs. Cependant, le resultat le plus important sera que le bruit perturbe plus le transport des paires delocalisees, qui implique une resonance de Breit-Wigner a deux particules. Le transport parasite n'implique pour sa part qu'une resonance de Breit-Wigner a une particule. Dans le chapitre 4, nous reviendrons au systeme constitue de deux points quantiques entoures de deux fils

  10. 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

  11. Folds and Etudes

    ERIC Educational Resources Information Center

    Bean, Robert

    2007-01-01

    In this article, the author talks about "Folds" and "Etudes" which are images derived from anonymous typing exercises that he found in a used copy of "Touch Typing Made Simple". "Etudes" refers to the musical tradition of studies for a solo instrument, which is a typewriter. Typing exercises are repetitive attempts to type words and phrases…

  12. Etude energetique et modelisation d'un Systeme Hybride Eolien-Diesel avec stockage d'Air Comprime (SHEDAC)

    NASA Astrophysics Data System (ADS)

    Martinez, Nicolas

    Actuellement le Canada et plus specialement le Quebec, comptent une multitude de sites isoles dont !'electrification est assuree essentiellement par des generatrices diesel a cause, principalement, de l'eloignement du reseau central de disuibution electrique. Bien que consideree comme une source fiable et continue, 1 'utilisation des generatrices diesel devient de plus en plus problematique d'un point de vue energetique, economique et environnemental. Dans le but d'y resoudre et de proposer une methode d'approvisionnement plus performante, mains onereuse et plus respectueuse de l'environnement, l'usage des energies renouvelables est devenu indispensable. Differents travaux ont alors demontre que le couplage de ces energies avec des generauices diesel, formant des systemes hybrides, semble etre une des meilleures solutions. Parmi elles, le systeme hybride eolien-diesel avec stockage par air comprime (SHEDAC) se presente comme une configuration optimale pour 1 'electrification des sites isoles. En effet, differentes etudes ont permis de mettre en avant l'efficacite du stockage par air comprime, par rapport a d'autres technologies de stockage, en complement d'un systeme hybride eolien-diesel. Plus precisement, ce systeme se compose de sous-systemes qui sont: des eoliennes, des generatrices diesel et une chaine de compression et de stockage d'air comprime qui est ensuite utilisee pour suralimenter les generatrices. Ce processus permet ainsi de reduire Ia consommation en carburant tout en agrandissant la part d'energie renouvelable dans Ia production electrique. A ce jour, divers travaux de recherche ont pennis de demontrer I' efficacite d 'un tel systeme et de presenter une variete de configurations possibles. A travers ce memoire, un logiciel de dimensionnement energetique y est elabore dans le but d'unifom1iser !'approche energetique de cette technologie. Cet outil se veut etre une innovation dans le domaine puisqu'il est actuellement impossible de dimensionner un

  13. Methodes de caracterisation des proprietes thermomecaniques d'un acier martensitique =

    NASA Astrophysics Data System (ADS)

    Ausseil, Lucas

    Le but de l'etude est de developper des methodes permettant de mesurer les proprietes thermomecaniques d'un acier martensitique lors de chauffe rapide. Ces donnees permettent d'alimenter les modeles d'elements finis existant avec des donnees experimentales. Pour cela, l'acier 4340 est utilise. Cet acier est notamment utilise dans les roues d'engrenage, il a des proprietes mecaniques tres interessantes. Il est possible de modifier ses proprietes grâce a des traitements thermiques. Le simulateur thermomecanique Gleeble 3800 est utilise. Il permet de tester theoriquement toutes les conditions presentes dans les procedes de fabrication. Avec les tests de dilatation realises dans ce projet, les temperatures exactes de changement de phases austenitiques et martensitiques sont obtenues. Des tests de traction ont aussi permis de deduire la limite d'elasticite du materiau dans le domaine austenitique allant de 850 °C a 1100 °C. L'effet des deformations sur la temperature de debut de transformation est montre qualitativement. Une simulation numerique est aussi realisee pour comprendre les phenomenes intervenant pendant les essais.

  14. Methodes de calcul des forces aerodynamiques pour les etudes des interactions aeroservoelastiques

    NASA Astrophysics Data System (ADS)

    Biskri, Djallel Eddine

    L'aeroservoelasticite est un domaine ou interagissent la structure flexible d'un avion, l'aerodynamique et la commande de vol. De son cote, la commande du vol considere l'avion comme une structure rigide et etudie l'influence du systeme de commande sur la dynamique de vol. Dans cette these, nous avons code trois nouvelles methodes d'approximation de forces aerodynamiques: Moindres carres corriges, Etat minimal corrige et Etats combines. Dans les deux premieres methodes, les erreurs d'approximation entre les forces aerodynamiques approximees par les methodes classiques et celles obtenues par les nouvelles methodes ont les memes formes analytiques que celles des forces aerodynamiques calculees par LS ou MS. Quant a la troisieme methode, celle-ci combine les formulations des forces approximees avec les methodes standards LS et MS. Les vitesses et frequences de battement et les temps d'executions calcules par les nouvelles methodes versus ceux calcules par les methodes classiques ont ete analyses.

  15. Vers des boites quantiques a base de graphene

    NASA Astrophysics Data System (ADS)

    Branchaud, Simon

    Le graphene est un materiau a base de carbone qui est etudie largement depuis 2004. De tres nombreux articles ont ete publies tant sur les proprietes electroniques, qu'optiques ou mecaniques de ce materiel. Cet ouvrage porte sur l'etude des fluctuations de conductance dans le graphene, et sur la fabrication et la caracterisation de nanostructures gravees dans des feuilles de ce cristal 2D. Des mesures de magnetoresistance a basse temperature ont ete faites pres du point de neutralite de charge (PNC) ainsi qu'a haute densite electronique. On trouve deux origines aux fluctuations de conductance pres du PNC, soit des oscillations mesoscopiques provenant de l'interference quantique, et des fluctuations dites Hall quantique apparaissant a plus haut champ (>0.5T), semblant suivre les facteurs de remplissage associes aux monocouches de graphene. Ces dernieres fluctuations sont attribuees a la charge d'etats localises, et revelent un precurseur a l'effet Hall quantique, qui lui, ne se manifeste pas avant 2T. On arrive a extraire les parametres caracterisant l'echantillon a partir de ces donnees. A la fin de cet ouvrage, on effectue des mesures de transport dans des constrictions et ilots de graphene, ou des boites quantiques sont formees. A partir de ces mesures, on extrait les parametres importants de ces boites quantiques, comme leur taille et leur energie de charge.

  16. Analyse experimentale des performances d'une batterie au lithium pour l'aeronautique

    NASA Astrophysics Data System (ADS)

    Bonnin, Romain

    Ce memoire a pour objectif d'identifier et d'etudier les performances necessaires pour qu'une batterie au lithium puisse etre utilisee dans le secteur de l'aeronautique. C'est pourquoi dans le cadre de notre recherche, nous allons proposer une procedure de tests permettant d'analyser et de determiner si la batterie au lithium peut etre implantee dans un avion. En vue de repondre a l'analyse des performances, une etude des fonctionnalites demandees par l'avion ainsi que des normes preexistantes vont etre effectuees. Suite a cette etape, nous allons elaborer un banc d'essais. Une fois le banc d'essais acheve, nous allons tester une batterie au lithium qui est supposee disposer de toutes les caracteristiques techniques requises pour etre implantee dans un avion. Ces tests nous permettront donc d'emettre un avis sur l'utilisation des batteries au lithium dans le domaine de l'aeronautique.

  17. Le transfert de connaissances entre les mathematiques et les sciences. Une etude exploratoire aupres d'eleves de 4e secondaire

    NASA Astrophysics Data System (ADS)

    Samson, Ghislain

    2003-06-01

    Au moment ou dans plusieurs pays on travaille a refondre les programmes d'etudes, tant au primaire qu'au secondaire, l'interet pour le transfert renait. Un des concepts fondamentaux en apprentissage consiste en l'habilete a reutiliser de facon consciente et efficace un acquis d'une situation a une autre situation. Cette recherche emane de preoccupations professionnelles au moment ou le chercheur etait enseignant au secondaire. Au cours de ces annees, il lui a ete possible de constater que plusieurs eleves percevaient difficilement les liens presents entre les disciplines mathematiques et scientifiques. Des travaux en psychologie cognitive et plus particulierement selon une perspective du traitement de l'information ont servi de cadre de reference pour evaluer et analyser les capacites de transfert aupres d'eleves de 4e secondaire. Ce cadre de reference permet de formuler le principal objectif qui est de mieux comprendre le processus de transfert chez des eleves en situation de resolution de problemes scientifiques. Cette these s'interesse donc au transfert en tant que phenomene important du processus d'apprentissage au sens de l'integration. La methode de recherche choisie, de nature qualitative, est principalement axee sur l'evaluation de la capacite a transferer des connaissances lors d'une epreuve et d'un entretien. Pour evaluer ce potentiel de transfert, nous avons elabore deux outils: une epreuve en mathematiques et en sciences et un guide d'entretien. Pour la passation de l'epreuve, le chercheur a pu compter sur la collaboration de 130 sujets provenant de deux ecoles. L'entretien complete la prise de donnees avec 13 sujets ayant accepte de poursuivre l'etude. Les donnees recueillies par ces instruments font ensuite l'objet d'une analyse de contenu. En premier lieu, les verbatims de l'epreuve et de l'entretien ont ete transcrits, puis codifies. La correction des reponses fournies pour les problemes resolus s'est faite a partir d'une grille d

  18. L'etude de l'InP et du GaP suite a l'implantation ionique de Mn et a un recuit thermique

    NASA Astrophysics Data System (ADS)

    Bucsa, Ioan Gigel

    Cette these est dediee a l'etude des materiaux InMnP et GaMnP fabriques par implantation ionique et recuit thermique. Plus precisement nous avons investigue la possibilite de former par implantation ionique des materiaux homogenes (alliages) de InMnP et GaMnP contenant de 1 a 5 % atomiques de Mn qui seraient en etat ferromagnetique, pour des possibles applications dans la spintronique. Dans un premier chapitre introductif nous donnons les motivations de cette recherche et faisons une revue de la litterature sur ce sujet. Le deuxieme chapitre decrit les principes de l'implantation ionique, qui est la technique utilisee pour la fabrication des echantillons. Les effets de l'energie, fluence et direction du faisceau ionique sur le profil d'implantation et la formation des dommages seront mis en evidence. Aussi dans ce chapitre nous allons trouver des informations sur les substrats utilises pour l'implantation. Les techniques experimentales utilisees pour la caracterisation structurale, chimique et magnetique des echantillons, ainsi que leurs limitations sont presentees dans le troisieme chapitre. Quelques principes theoriques du magnetisme necessaires pour la comprehension des mesures magnetiques se retrouvent dans le chapitre 4. Le cinquieme chapitre est dedie a l'etude de la morphologie et des proprietes magnetiques des substrats utilises pour implantation et le sixieme chapitre, a l'etude des echantillons implantes au Mn sans avoir subi un recuit thermique. Notamment nous allons voir dans ce chapitre que l'implantation de Mn a plus que 1016 ions/cm 2 amorphise la partie implantee du materiau et le Mn implante se dispose en profondeur sur un profil gaussien. De point de vue magnetique les atomes implantes se trouvent dans un etat paramagnetique entre 5 et 300 K ayant le spin 5/2. Dans le chapitre 7 nous presentons les proprietes des echantillons recuits a basses temperatures. Nous allons voir que dans ces echantillons la couche implantee est polycristalline et les

  19. French Research in Acoustics and Signal Processing: Report on Introductory Visit

    DTIC Science & Technology

    1986-05-01

    CEPHAG (Centre d’Etude des Phenomenes Aleatoires et Geophysiques ), which is associated with the Institut National Polytechnique at Grenoble. We were...measurement programs. Centre d’Etude des Phenomenes Aleatoires et Geophysiques (CEPHAG), Institut National Polytechnique, Universite de Grenoble, 23 May...69288 Lyon Cedex, France, Tel 72.32.50.67. CENTRE D’ETUDE DES PHENOMENES ALEATOIRES ET GEOPHYSIQUES (CEPHAG), Grenoble. Prof. J. L. Lacoume

  20. Developpement D'un Modele Climatique Regional: Fizr Simulation des Conditions de Janvier de la Cote Ouest Nord Americaine

    NASA Astrophysics Data System (ADS)

    Goyette, Stephane

    1995-11-01

    Le sujet de cette these concerne la modelisation numerique du climat regional. L'objectif principal de l'exercice est de developper un modele climatique regional ayant les capacites de simuler des phenomenes de meso-echelle spatiale. Notre domaine d'etude se situe sur la Cote Ouest nord americaine. Ce dernier a retenu notre attention a cause de la complexite du relief et de son controle sur le climat. Les raisons qui motivent cette etude sont multiples: d'une part, nous ne pouvons pas augmenter, en pratique, la faible resolution spatiale des modeles de la circulation generale de l'atmosphere (MCG) sans augmenter a outrance les couts d'integration et, d'autre part, la gestion de l'environnement exige de plus en plus de donnees climatiques regionales determinees avec une meilleure resolution spatiale. Jusqu'alors, les MCG constituaient les modeles les plus estimes pour leurs aptitudes a simuler le climat ainsi que les changements climatiques mondiaux. Toutefois, les phenomenes climatiques de fine echelle echappent encore aux MCG a cause de leur faible resolution spatiale. De plus, les repercussions socio-economiques des modifications possibles des climats sont etroitement liees a des phenomenes imperceptibles par les MCG actuels. Afin de circonvenir certains problemes inherents a la resolution, une approche pratique vise a prendre un domaine spatial limite d'un MCG et a y imbriquer un autre modele numerique possedant, lui, un maillage de haute resolution spatiale. Ce processus d'imbrication implique alors une nouvelle simulation numerique. Cette "retro-simulation" est guidee dans le domaine restreint a partir de pieces d'informations fournies par le MCG et forcee par des mecanismes pris en charge uniquement par le modele imbrique. Ainsi, afin de raffiner la precision spatiale des previsions climatiques de grande echelle, nous developpons ici un modele numerique appele FIZR, permettant d'obtenir de l'information climatique regionale valide a la fine echelle spatiale

  1. Des proprietes de l'etat normal du modele de Hubbard bidimensionnel

    NASA Astrophysics Data System (ADS)

    Lemay, Francois

    Depuis leur decouverte, les etudes experimentales ont demontre que les supra-conducteurs a haute temperature ont une phase normale tres etrange. Les proprietes de ces materiaux ne sont pas bien decrites par la theorie du liquide de Fermi. Le modele de Hubbard bidimensionnel, bien qu'il ne soit pas encore resolu, est toujours considere comme un candidat pour expliquer la physique de ces composes. Dans cet ouvrage, nous mettons en evidence plusieurs proprietes electroniques du modele qui sont incompatibles avec l'existence de quasi-particules. Nous montrons notamment que la susceptibilite des electrons libres sur reseau contient des singularites logarithmiques qui influencent de facon determinante les proprietes de la self-energie a basse frequence. Ces singularites sont responsables de la destruction des quasi-particules. En l'absence de fluctuations antiferromagnetiques, elles sont aussi responsables de l'existence d'un petit pseudogap dans le poids spectral au niveau de Fermi. Les proprietes du modele sont egalement etudiees pour une surface de Fermi similaire a celle des supraconducteurs a haute temperature. Un parallele est etabli entre certaines caracteristiques du modele et celles de ces materiaux.

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

    NASA Astrophysics Data System (ADS)

    El Mansouri, Souleimane

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

  3. Hazard Studies for Solid Propellant Rocket Motors (Etude des Risque pour les Moteurs-Fusees a Propergols Solides)

    DTIC Science & Technology

    1990-09-01

    RESEARCH AND DEVELOPMENT (ORGANISATION DU TRAITE DE LATIANTIOUF NORD) AGARDograph No.3 16 Hazard Studies for Solid Propellant Rocket Motors (Etudes de...member nations to use their research and development capabilities for the common benefit of the NATO community; - Providing scientific and technical...advice and assistance to the Military Committee in the field of aerospace research and development (with particular regard to its military application

  4. Methode d'identification parametrique pour la surveillance in situ des joints a recouvrement par propagation d'ondes vibratoires

    NASA Astrophysics Data System (ADS)

    Francoeur, Dany

    Cette these de doctorat s'inscrit dans le cadre de projets CRIAQ (Consortium de recherche et d'innovation en aerospatiale du Quebec) orientes vers le developpement d'approches embarquees pour la detection de defauts dans des structures aeronautiques. L'originalite de cette these repose sur le developpement et la validation d'une nouvelle methode de detection, quantification et localisation d'une entaille dans une structure de joint a recouvrement par la propagation d'ondes vibratoires. La premiere partie expose l'etat des connaissances sur l'identification d'un defaut dans le contexte du Structural Health Monitoring (SHM), ainsi que la modelisation de joint a recouvrements. Le chapitre 3 developpe le modele de propagation d'onde d'un joint a recouvrement endommage par une entaille pour une onde de flexion dans la plage des moyennes frequences (10-50 kHz). A cette fin, un modele de transmission de ligne (TLM) est realise pour representer un joint unidimensionnel (1D). Ce modele 1D est ensuite adapte a un joint bi-dimensionnel (2D) en faisant l'hypothese d'un front d'onde plan incident et perpendiculaire au joint. Une methode d'identification parametrique est ensuite developpee pour permettre a la fois la calibration du modele du joint a recouvrement sain, la detection puis la caracterisation de l'entaille situee sur le joint. Cette methode est couplee a un algorithme qui permet une recherche exhaustive de tout l'espace parametrique. Cette technique permet d'extraire une zone d'incertitude reliee aux parametres du modele optimal. Une etude de sensibilite est egalement realisee sur l'identification. Plusieurs resultats de mesure sur des joints a recouvrements 1D et 2D sont realisees permettant ainsi l'etude de la repetabilite des resultats et la variabilite de differents cas d'endommagement. Les resultats de cette etude demontrent d'abord que la methode de detection proposee est tres efficace et permet de suivre la progression d'endommagement. De tres bons resultats

  5. Littoral Infrared Ship Self Defence Technology Studies (Autodefense cotiere infrarouge des navires etudes technologiques)

    DTIC Science & Technology

    2014-05-01

    de simulation du Simulateur de Contre- mesures de la Menace Navale afin de pouvoir inclure des leurres et des autodirecteurs de missiles ; 4) Une...sur le littoral ; 2) La détection des petites cibles de surface sur le littoral ; 3) L’amélioration et la validation de la modélisation et du code...amélioration et une validation supplémentaire de la modélisation et du

  6. Etude de la Morphologie et de la Cinématique de l'Emission des Raies interdites autour des Etoiles T Tauri

    NASA Astrophysics Data System (ADS)

    Lavalley, Claudia

    2000-06-01

    Le phénomène de perte de masse joue un rôle essentiel dès les premières étapes de la formation stellaire et semble être intimement lié à l'accrétion de matière sur l'étoile, probablement par l'intermédiaire de champs magnétiques permettant de convertir l'énergie cinétique accrétée, en puissance d'éjection. Les étoiles T Tauri classiques, âgées de quelques millions d'années et présentant une faible extinction, offrent un excellent cadre pour étudier les régions internes des vents stellaires. Dans ce travail, je présente les premières études sur la morphologie des jets associés aux étoiles DG Tau, CW Tau et RW Aur à une résolution angulaire de 0.1'' et sur la cinématique à deux dimensions de l'émission des raies de [O I]?6300Å, [N II]?6583Å et [S II] ?6716,6731Å dans le jet de DG Tau. Ces données ont été obtenues avec deux techniques d'observation complètement nouvelles, devenues disponibles entre 1994 et 1998 au télescope CFH, et idéalement adaptées à ce problème: l'imagerie en bande étroite derrière l'optique adaptative (PUEO) qui fournit des données à très haute résolution angulaire (~0.1''), et la spectro-imagerie intégrale de champ (TIGRE/OASIS) qui donne accès à l'information spatiale et spectrale à 2D, à haute résolution angulaire (ici ~0.5''-0.75'') et moyenne résolution spectrale (100-170 km/s). Les trois jets étudiés, résolus pour la première fois à partir de 55 u.a. de l'étoile, présentent une largeur similaire (30-35 u.a.) jusqu'à 100 u.a. et une morphologie dominée par des noeuds d'émission. Les jets des étoiles à faible excès infrarouge CW Tau et RW Aur sont très similaires aux deux autres jets des sources peu enfouies observés jusqu'à présent à la même échelle spatiale. Le jet de DG Tau, plus perturbé que les deux autres, et provenant d'une source avec une enveloppe encore importante, est aussi très similaire au seul autre jet associé à une source encore enfouie r

  7. Le changement comme tradition dans la recherche et la formation a la recherche en biotechnologie et en peripherie Etude de cas en sciences de la sante, sciences naturelles et genie

    NASA Astrophysics Data System (ADS)

    Bourque, Claude Julie

    Le champ de la recherche scientifique et de la formation a la recherche est traverse depuis quelques dizaines d'annees par plusieurs courants et discours associes au changement, mais peu de travaux empiriques permettent de comprendre ce qui change concretement. C'est la contribution originale de cette these au champ de l'education, plus specifiquement a l'etude sociologique de l'enseignement superieur ou sont concentrees les activites liees a la triade thematique du programme doctoral dans lequel elle a ete produite : recherche, formation et pratique. L'enquete-terrain a ete realisee en 2009 et 2010 aupres de 808 repondants affilies a 60 etablissements au Quebec et a produit un vaste materiau de nature mixte (donnees quantitatives et qualitatives). Un portrait de la nebuleuse biotechnologique qui touche les secteurs des sciences de la sante, des sciences naturelles et du genie a ete realise. Ce domaine concerne des dizaines de disciplines et se revele de nature transdisciplinaire, mais les pratiques n'y sont pas davantage marquees par le changement que celles d'autres domaines connexes. Les dynamiques sociales ont fait l'objet d'analyses comparatives dans quatre contextes: le choix des programmes, des objets et des methodes, le financement, la diffusion et la planification de la carriere. Les resultats indiquent que les echanges entre les agents traditionnellement situes au coeur des activites de recherche dominent ces dynamiques dans tous les contextes etudies. L'etude des representations au fondement des pratiques a revele l'existence de trois ecoles de pensee qui coexistent dans le champ scientifique: academique, pragmatique et economiste. Ces ecoles permettent de categoriser les agents en fonction des zones de fractures qui marquent leurs oppositions tout en identifiant ce qu'ils ont en commun. Les representations et les pratiques liees a la formation temoignent d'un habitus plutot homogene, alors que les contradictions semblent plus souvent ancrees dans des

  8. Le role du phytoplancton de petite taille (<20 mum) dans les variations des proprietes optiques des eaux du Saint-Laurent

    NASA Astrophysics Data System (ADS)

    Mas, Sebastien

    proprietes biooptiques, particulierement l'absorption, etaient attribuables a la contribution du phytoplancton <20 mum. Ceci confirme l'importance de la structure de taille des communautes phytoplanctoniques dans les modeles bio-optiques appliques au Saint-Laurent. L'ensemble des resultats a permis de mettre en evidence l'importance des mecanismes de photoacclimatation et de synchronisation du cycle cellulaire du phytoplancton sur les variations journalieres des IOPs, ainsi que de l'etat physiologique relie au stade de croissance sur les variations temporelles a long terme des IOPs. De plus, le phytoplancton <20 mum contribue de maniere importante aux IOPs et a leur variabilite dans l'Estuaire et le Golfe du St-Laurent, et ce particulierement pour l'absorption. Cette etude de doctorat souligne donc l'importance du phytoplancton <20 mum sur la variabilite des IOPs des oceans.

  9. Etude des interdiffusions en phase solide dans le contact Er/GaAs

    NASA Astrophysics Data System (ADS)

    Députier, S.; Guivarc'h, A.; Caulet, J.; Minier, M.; Guérin, R.

    1994-05-01

    Solid state interdiffusions between a thin film of erbium deposited under vacuum conditions and (001) and (111) GaAs substrates were investigated in the temperature range 350-800 ^{circ}C. Complementary analysis methods (RBS, X-ray diffraction) allow us to point out, according to annealing temperatures, successives steps of the interaction corresponding to different mixtures of phases, essentially binaries. These steps are strongly depending on the GaAs substrate orientation, especially the final step of the interdiffusions. On (001) GaAs, only two steps have been observed : no visible interaction is noticed between erbium and GaAs before 600 ^{circ}C ; the interaction begins at 600 ^{circ}C, evolves slightly and leads at 800 ^{circ}C to the nominal composition " Er{10}GaAs " which corresponds to a mixture of several phases Er5Ga3, Er and ErAs. On (111) GaAs, several steps of interaction have been found ; first of all, erbium reacts with the substrate at 400 ^{circ}C (Er5Ga3 + Er mixture), then the reaction is continuing at 600 ^{circ}C (Er5Ga3 + Er + ErAs mixture) before reaching at 800 ^{circ}C the nominal composition " Er{1,5}GaAs ", which is in fact a mixture of the three binaries ErAs + ErGa2 + Er3Ga5. It can be noticed that the 800 ^{circ}C annealing is not sufficient to reach the mixture of the phases ErAs + Ga which, according to the ternary phase diagram, should be the final stage of the interaction Er/GaAs. The analysis of the Er/GaAs interdiffusions shows that ErAs is the " key " compound around which the interaction progresses. This compound appears as an ideal candidate to realize epitaxial ErAs/GaAs heterostructures. Les interdiffusions en phase solide entre une couche mince d'erbium déposée dans des conditions d'ultra-vide et des substrats de GaAs orientés (001) et (111) ont été étudiées après des traitements thermiques d'une heure entre 350 et 800 ^{circ}C. L'utilisation de techniques complémentaires d'analyse (RBS, diffraction X) a permis

  10. Evaluation d'une approche pedagogique respectant les facons d'apprendre des filles en sciences et en TIC en 9e annee au Nouveau-Brunswick

    NASA Astrophysics Data System (ADS)

    Lirette-Pitre, Nicole T.

    2009-07-01

    La reussite scolaire des filles les amene de plus en plus a poursuivre une formation postsecondaire et a exercer des professions qui demandent un haut niveau de connaissances et d'expertise scientifique. Toutefois, les filles demeurent toujours tres peu nombreuses a envisager une carriere en sciences (chimie et physique), en ingenierie ou en TIC (technologie d'information et de la communication), soit une carriere reliee a la nouvelle economie. Pour plusieurs filles, les sciences et les TIC ne sont pas des matieres scolaires qu'elles trouvent interessantes meme si elles y reussissent tres bien. Ces filles admettent que leurs experiences d'apprentissage en sciences et en TIC ne leur ont pas permis de developper un interet ni de se sentir confiante en leurs habiletes a reussir dans ces matieres. Par consequent, peu de filles choisissent de poursuivre leurs etudes postsecondaires dans ces disciplines. La theorie sociocognitive du choix carriere a ete choisie comme modele theorique pour mieux comprendre quelles variables entrent en jeu lorsque les filles choisissent leur carriere. Notre etude a pour objet la conception et l'evaluation de l'efficacite d'un materiel pedagogique concu specifiquement pour ameliorer les experiences d'apprentissage en sciences et en TIC des filles de 9e annee au Nouveau-Brunswick. L'approche pedagogique privilegiee dans notre materiel a mis en oeuvre des strategies pedagogiques issues des meilleures pratiques que nous avons identifiees et qui visaient particulierement l'augmentation du sentiment d'auto-efficacite et de l'interet des filles pour ces disciplines. Ce materiel disponible par Internet a l'adresse http://www.umoncton.ca/lirettn/scientic est directement en lien avec le programme d'etudes en sciences de la nature de 9e annee du Nouveau-Brunswick. L'evaluation de l'efficacite de notre materiel pedagogique a ete faite selon deux grandes etapes methodologiques: 1) l'evaluation de l'utilisabilite et de la convivialite du materiel et 2

  11. Etude thermo-hydraulique de l'ecoulement du moderateur dans le reacteur CANDU-6

    NASA Astrophysics Data System (ADS)

    Mehdi Zadeh, Foad

    importante, se traduisant par l'accroissement de la puissance du reacteur. Ceci peut avoir des consequences majeures pour la surete nucleaire. Une modelisation CFD (Computational Fluid Dynamics) detaillee tenant compte des effets locaux s'avere donc necessaire. Le but de ce travail de recherche est de modeliser le comportement complexe de l'ecoulement du moderateur au sein de la cuve d'un reacteur nucleaire CANDU-6, notamment a proximite des tubes de calandre. Ces simulations servent a identifier les configurations possibles de l'ecoulement dans la calandre. Cette etude consiste ainsi a formuler des bases theoriques a l'origine des instabilites macroscopiques du moderateur, c.-a-d. des mouvements asymetriques qui peuvent provoquer l'ebullition du moderateur. Le defi du projet est de determiner l'impact de ces configurations de l'ecoulement sur la reactivite du reacteur CANDU-6.

  12. Etude de la Production de Paires de Leptons dans les Interactions Proton-Beryllium a 450 GEV

    NASA Astrophysics Data System (ADS)

    Aubry, Pierre Rene Roger

    L'experience HELIOS a fait une etude precise de la production des paires e^+e^-, mu^+mu^-, mu ^+mu^-+nu, et mu^+/- e^+/- dans les interactions p-Be a 450 GeV. Le detecteur comporte un spectrometre a electrons, un spectrometre a muons, et un ensemble de calorimetres qui peuvent mesurer les photons et l'energie manquante emportee par les neutrinos. Les paires de leptons sont observees dans la region cinematique ^1: eqalign {2/m_mu 6 GeV cr E_{e}&>2.8 GeV cr.25&des sources connues: desintegrations hadroniques de mesons, charme, bremsstrahlung. L'experience n'a pas observe de production anormale de dielectrons et de dimuons de basses masses dans la region de rapidite centrale. Le spectre en energie manquante permet d'identifier clairement les desintegrations semileptoniques de particules charmees. Une mesure de la section efficace de production de particules charmees dans les interactions p-Be a 450 GeV a ete faite:sigma_{c|c}= 24+/-8 (statistique) +/-16 (systématique) mu barn/nucléon. L'etude de la distribution en energie manquante des dimuons de masse intermediaire (1.2 GeV

  13. Modelisation de l'erosion et des sources de pollution dans le bassin versant Iroquois/Blanchette dans un contexte de changements climatiques

    NASA Astrophysics Data System (ADS)

    Coulibaly, Issa

    Principale source d'approvisionnement en eau potable de la municipalite d'Edmundston, le bassin versant Iroquois/Blanchette est un enjeu capital pour cette derniere, d'ou les efforts constants deployes pour assurer la preservation de la qualite de son eau. A cet effet, plusieurs etudes y ont ete menees. Les plus recentes ont identifie des menaces de pollution de diverses origines dont celles associees aux changements climatiques (e.g. Maaref 2012). Au regard des impacts des modifications climatiques annonces a l'echelle du Nouveau-Brunswick, le bassin versant Iroquois/Blanchette pourrait etre fortement affecte, et cela de diverses facons. Plusieurs scenarios d'impacts sont envisageables, notamment les risques d'inondation, d'erosion et de pollution a travers une augmentation des precipitations et du ruissellement. Face a toutes ces menaces eventuelles, l'objectif de cette etude est d'evaluer les impacts potentiels des changements climatiques sur les risques d'erosion et de pollution a l'echelle du bassin versant Iroquois/Blanchette. Pour ce faire, la version canadienne de l'equation universelle revisee des pertes en sol RUSLE-CAN et le modele hydrologique SWAT ( Soil and Water Assessment Tool) ont ete utilises pour modeliser les risques d'erosion et de pollution au niveau dans la zone d'etude. Les donnees utilisees pour realiser ce travail proviennent de sources diverses et variees (teledetections, pedologiques, topographiques, meteorologiques, etc.). Les simulations ont ete realisees en deux etapes distinctes, d'abord dans les conditions actuelles ou l'annee 2013 a ete choisie comme annee de reference, ensuite en 2025 et 2050. Les resultats obtenus montrent une tendance a la hausse de la production de sediments dans les prochaines annees. La production maximale annuelle augmente de 8,34 % et 8,08 % respectivement en 2025 et 2050 selon notre scenario le plus optimiste, et de 29,99 % en 2025 et 29,72 % en 2050 selon le scenario le plus pessimiste par rapport a celle

  14. Etude de pratiques d'enseignement relatives a la modelisation en sciences et technologies avec des enseignants du secondaire

    NASA Astrophysics Data System (ADS)

    Aurousseau, Emmanuelle

    Les modeles sont des outils amplement utilises en sciences et technologies (S&T) afin de representer et d’expliquer un phenomene difficilement accessible, voire abstrait. La demarche de modelisation est presentee de maniere explicite dans le programme de formation de l’ecole quebecoise (PFEQ), notamment au 2eme cycle du secondaire (Quebec. Ministere de l'Education du Loisir et du Sport, 2007a). Elle fait ainsi partie des sept demarches auxquelles eleves et enseignants sont censes recourir. Cependant, de nombreuses recherches mettent en avant la difficulte des enseignants a structurer leurs pratiques d’enseignement autour des modeles et de la demarche de modelisation qui sont pourtant reconnus comme indispensables. En effet, les modeles favorisent la conciliation des champs concrets et abstraits entre lesquels le scientifique, meme en herbe, effectue des allers-retours afin de concilier le champ experimental de reference qu’il manipule et observe au champ theorique relie qu’il construit. L’objectif de cette recherche est donc de comprendre comment les modeles et la demarche de modelisation contribuent a faciliter l’articulation du concret et de l’abstrait dans l’enseignement des sciences et des technologies (S&T) au 2eme cycle du secondaire. Pour repondre a cette question, nous avons travaille avec les enseignants dans une perspective collaborative lors de groupes focalises et d’observation en classe. Ces dispositifs ont permis d’examiner les pratiques d’enseignement que quatre enseignants mettent en oeuvre en utilisant des modeles et des demarches de modelisation. L’analyse des pratiques d’enseignement et des ajustements que les enseignants envisagent dans leur pratique nous permet de degager des connaissances a la fois pour la recherche et pour la pratique des enseignants, au regard de l’utilisation des modeles et de la demarche de modelisation en S&T au secondaire.

  15. Determination des Parametres Atmospheriques des Etoiles Naines Blanches de Type DB

    NASA Astrophysics Data System (ADS)

    Beauchamp, Alain

    1995-01-01

    , ML1, ML2 et ML3, de la theorie de longueur de melange. Nous avons calcule une grille de spectres synthetiques avec les memes parametrisations que la grille de modeles d'atmospheres. Notre traitement de l'elargissement des raies de l'helium neutre a ete ameliore de facon significative par rapport aux etudes precedentes. D'une part, nous tenons compte de l'elargissement des raies produit par les interactions entre l'emetteur et les particules neutres (elargissements par resonance et de van der Waals) en plus de celui par les particules chargees (elargissement Stark). D'autre part, nous avons calcule nous-memes les profils Stark avec les meilleures theories d'elargissement disponibles pour la majorite des raies observees; ces profils depassent en qualite ce qui a ete publie jusqu'a ce jour. Nous avons calcule la distribution de masse des etoiles DB plus chaudes que 15,000 K. La distribution de masse des DB est tres etroite, avec environ les trois quarts des etoiles incluses dans l'intervalle 0.55-0.65 Modot. La masse moyenne des etoiles DB est de 0.58 M_⊙ avec sigma = 0.07. La difference principale entre les distributions de masse des DB et DA est la faible proportion de DB dans les ailes de la distribution, ce qui implique que les DA moins massives que ~0.4 M odot et plus massives que ~0.8 M_⊙ ne se convertissent pas en DB. Les objets les plus massifs de notre echantillon sont de type DBA, ce qui suggere que la masse elevee favorise la visibilite de l'hydrogene. (Abstract shortened by UMI.).

  16. Un accumulateur echangeur de chaleur hybride pour la gestion simultanee des energies solaire et electrique

    NASA Astrophysics Data System (ADS)

    Ait Hammou, Zouhair

    Cette etude porte sur la conception d'un accumulateur echangeur de chaleur hybride (AECH) pour la gestion simultanee des energies solaire et electrique. Un modele mathematique reposant sur les equations de conservation de la quantite d'energie est expose. Il est developpe pour tester differents materiaux de stockage, entre autres, les materiaux a changement de phase (solide/liquide) et les materiaux de stockage sensible. Un code de calcul est mis en eeuvre sur ordinateur, puis valide a l'aide des resultats analytiques et numeriques de la litterature. En parallele, un prototype experimental a echelle reduite est concu au laboratoire afin de valider le code de calcul. Des simulations sont effectuees pour etudier les effets des parametres de conception et des materiaux de stockage sur le comportement thermique de l'AECH et sur la consommation d'energie electrique. Les resultats des simulations sur quatre mois d'hiver montrent que la paraffine n-octadecane et l'acide caprique sont deux candidats souhaitables pour le stockage d'energie destine au chauffage des habitats. L'utilisation de ces deux materiaux dans l'AECH permet de reduire la consommation d'energie electrique de 32% et d'aplanir le probleme de pointe electrique puisque 90% de l'energie electrique est consommee durant les heures creuses. En plus, en adoptant un tarif preferentiel, le calcul des couts lies a la consommation d'energie electrique montre que le consommateur adoptant ce systeme beneficie d'une reduction de 50% de la facture d'electricite.

  17. Etude des melanges co-continus d'acide polylactique et d'amidon thermoplastique (PLA/TPS)

    NASA Astrophysics Data System (ADS)

    Chavez Garcia, Maria Graciela

    Les melanges co-continus sont des melanges polymeriques ou chaque composant se trouve dans une phase continue. Pour cette raison, les caracteristiques de chacun des composants se combinent et il en resulte un materiau avec une morphologie et des proprietes particulieres. L'acide polylactique (PLA) et l'amidon thermoplastique (TPS) sont des biopolymeres qui proviennent de ressources renouvelables et qui sont biodegradables. Dans ce projet, differents melanges de PLA et TPS a une haute concentration de TPS ont ete prepares dans une extrudeuse bi-vis afin de generer des structures co-continues. Grace a la technique de lixiviation selective, le TPS est enleve pour creer une structure poreuse de PLA qui a pu etre analysee au moyen de la microtomographie R-X et de la microscopie electronique a balayage MEB. L'analyse des images 2D et 3D confirme la presence de la structure co-continue dans les melanges dont la concentration en TPS. se situe entre 66% et 80%. L'effet de deux plastifiants, le glycerol seul et le melange de glycerol et de sorbitol, dans la formulation de TPS est etudie dans ce travail. De plus, nous avons evalue l'effet du PLA greffe a l'anhydride maleique (PLAg) en tant que compatibilisant. On a trouve que la phase de TPS obtenue avec le glycerol est plus grande. L'effet de recuit sur la taille de phases est aussi analyse. Grace aux memes techniques d'analyse, on a etudie l'effet du procede de moulage par injection sur la morphologie. On a constate que les pieces injectees presentent une microstructure heterogene et differente entre la surface et le centre de la piece. Pres de la surface, une peau plus riche en PLA est presente et les phases de TPS y sont allongees sous forme de lamelles. Plus au centre de la piece, une morphologie plus cellulaire est observee pour chaque phase continue. L'effet des formulations sur les proprietes mecaniques a aussi ete etudie. Les pieces injectees dont la concentration de TPS est plus grande presentent une moindre

  18. Utilisation d'images aeroportees a tres haute resolution spatiale pour l'estimation de la vigueur des peuplements forestiers du nord-ouest du Nouveau-Brunswick

    NASA Astrophysics Data System (ADS)

    Louis, Ognel Pierre

    Le but de cette etude est de developper un outil permettant d'estimer le niveau de risque de perte de vigueur des peuplements forestiers de la region de Gounamitz au nord-ouest du Nouveau-Brunswick via des donnees d'inventaires forestiers et des donnees de teledetection. Pour ce faire, un marteloscope de 100m x 100m et 20 parcelles d'echantillonnages ont ete delimites. A l'interieur de ces derniers, le niveau de risque de perte de vigueur des arbres ayant un DHP superieur ou egal a 9 cm a ete determine. Afin de caracteriser le risque de perte de vigueur des arbres, leurs positions spatiales ont ete repertoriees a partir d'un GPS en tenant compte des defauts au niveau des tiges. Pour mener a bien ce travail, les indices de vegetation et de textures et les bandes spectrales de l'image aeroportee ont ete extraits et consideres comme variables independantes. Le niveau de risque de perte de vigueur obtenu par espece d'arbre a travers les inventaires forestiers a ete considere comme variable dependante. En vue d'obtenir la superficie des peuplements forestiers de la region d'etude, une classification dirigee des images a partir de l'algorithme maximum de vraisemblance a ete effectuee. Le niveau de risque de perte de vigueur par type d'arbre a ensuite ete estime a l'aide des reseaux de neurones en utilisant un reseau dit perceptron multicouches. Il s'agit d'un modele de reseau de neurones compose de : 11 neurones sur la couche d'entree, correspondant aux variables independantes, 35 neurones sur la couche cachee et 4 neurones sur la couche de sortie. La prediction a partir des reseaux de neurones produit une matrice de confusion qui permet d'obtenir des mesures quantitatives d'estimation, notamment un pourcentage de classification globale de 91,7% pour la prediction du risque de perte de vigueur du peuplement de resineux et de 89,7% pour celui du peuplement de feuillus. L'evaluation de la performance des reseaux de neurones fournit une valeur de MSE globale de 0,04, et une

  19. Developpement d'une methode calorimetrique de mesure des pertes ac pour des rubans supraconducteurs a haute temperature critique

    NASA Astrophysics Data System (ADS)

    Dolez, Patricia

    Le travail de recherche effectue dans le cadre de ce projet de doctorat a permis la mise au point d'une methode de mesure des pertes ac destinee a l'etude des supraconducteurs a haute temperature critique. Pour le choix des principes de cette methode, nous nous sommes inspires de travaux anterieurs realises sur les supraconducteurs conventionnels, afin de proposer une alternative a la technique electrique, presentant lors du debut de cette these des problemes lies a la variation du resultat des mesures selon la position des contacts de tension sur la surface de l'echantillon, et de pouvoir mesurer les pertes ac dans des conditions simulant la realite des futures applications industrielles des rubans supraconducteurs: en particulier, cette methode utilise la technique calorimetrique, associee a une calibration simultanee et in situ. La validite de la methode a ete verifiee de maniere theorique et experimentale: d'une part, des mesures ont ete realisees sur des echantillons de Bi-2223 recouverts d'argent ou d'alliage d'argent-or et comparees avec les predictions theoriques donnees par Norris, nous indiquant la nature majoritairement hysteretique des pertes ac dans nos echantillons; d'autre part, une mesure electrique a ete realisee in situ dont les resultats correspondent parfaitement a ceux donnes par notre methode calorimetrique. Par ailleurs, nous avons compare la dependance en courant et en frequence des pertes ac d'un echantillon avant et apres qu'il ait ete endommage. Ces mesures semblent indiquer une relation entre la valeur du coefficient de la loi de puissance modelisant la dependance des pertes avec le courant, et les inhomogeneites longitudinales du courant critique induites par l'endommagement. De plus, la variation en frequence montre qu'au niveau des grosses fractures transverses creees par l'endommagement dans le coeur supraconducteur, le courant se partage localement de maniere a peu pres equivalente entre les quelques grains de matiere

  20. Etude de la variabilite des etoiles massives a l'aide de la photometrie et la spectroscopie

    NASA Astrophysics Data System (ADS)

    Lefevre, Laure

    Les étoiles Wolf-Rayet (WR) de population I sont les descendants évolués des étoiles massives de type O. Elles présentent de larges raies en émission produites par des atomes ionisés qui forment le vent stellaire chaud, den se et rapide. Il y a deux classes principales d'étoiles WR: les WN, ou les raies de l'azote dominent, et les WC (WO) ou les raies du carbone (de l'oxygène) dominent. Des observations récentes ont révelé que les vents sont "fragmentés" à petite et grande échelle, ce qui pourrait être relié en partie à des petites surdensités situées dans le vent en expansion. Cette thèse de doctorat présente la détection, l'analyse et l'interprétation, avec des outils statistiques avancés, de la variabilité dans les courbes de lumière, les vitesses radiales, et les spectres de deux étoiles WR caractéristiques (WR137 et WR123) et dans les étoiles OB observées par le satellite HIPPARCOS. Une campagne de spectroscopie intensive a été réalisée en 1999-2000 pour améliorer notre connaissance des composantes orbitales de WR137 (WC7pd+O9) et étudier les vents des WR et les conditions de formation des poussières dans de tels milieux. Le premier volet de cette thèse a permis de déduire de ces observations une orbite spectroscopique d'environ 13 ans qui confirme et précise les précédents résultats. Grace à l'analyse des spectres de cette campagne, ce travail a mis à jour une deuxième période d'oscillation de très faible amplitude de 0.83 j dans les spectres de WR137. Celle-ci pourrait être reliée aux pulsations ou à de grandes structures qui tourneraient dans le vent comme dans l'étoile EZ CMa (WR6). Une analyse en ondelettes a également permis d'isoler et de suivre pendant plusieurs heures des structures en haut des raies de CIII et CIV dans le spectre de WR137. De plus, la corrélation croisée a permis de voir que les raies formées à différentes distances de l'étoile sont probablement reliées entre elles. Enfin l

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

    NASA Astrophysics Data System (ADS)

    Boisvert, Mathieu

    " uphill " permet de conserver plus ou moins de graphite nodulaire a l'interieur des regions riches en silicium, alors que le reste du graphite precipite sous forme lamellaire/vermiculaire dans les regions interparticulaires. L'etude des poudres de fontes et la recherche des mecanismes regissant la morphologie du graphite dans les fontes coulees/moulees nous ont amenes a produire des poudres de fontes traitees au magnesium avant l'atomisation. Plusieurs resultats fondamentaux ont ete obtenus de la caracterisation des poudres traitees au magnesium et de leur comparaison avec des poudres de chimies similaires non traitees au magnesium. D'abord, il a ete possible d'observer des bifilms d'oxyde de silicium dans la structure du graphite primaire d'une poudre de fonte grise hypereutectique. Il s'agit des premieres images montrant la structure double de ces defauts, venant ainsi appuyer la theorie elaboree par le professeur John Campbell. Ensuite, il a ete montre que le traitement au magnesium forme une atmosphere protectrice gazeuse autogeneree qui empeche l'oxydation de la surface du bain liquide et donc, la formation et l'entrainement des bifilms. Le role du magnesium sur la morphologie du graphite est de diminuer le soufre en solution en formant des precipites de sulfure de magnesium et ainsi d'augmenter l'energie d'interface graphite-liquide. En reponse a cette grande energie d'interface graphite-liquide, le graphite cherche a minimiser son ratio surface/volume, ce qui favorise la formation de graphite spheroidal. De plus, deux types de germination ont ete observes dans la poudre de fonte hypereutectique traitee au magnesium. Le premier type est une germination heterogene sur un nombre limite de particules faites de magnesium, d'aluminium, de silicium et d'oxygene. Le deuxieme type est une germination homogene des nodules dans certaines regions du liquide plus riches en silicium. L'observation du centre reel tridimensionnel, en microscopie electronique en transmission en

  2. Plates-formes de microscopie et fluorescence par resonance de plasmons de surface appliquees a l'imagerie cellulaire

    NASA Astrophysics Data System (ADS)

    Chabot, Vincent

    L'elaboration de nouveaux medicaments repose sur les etudes pharmacologiques, dont le role est d'identifier de nouveaux composes actifs ou de nouvelles cibles pharmacologiques agissant entre autres au niveau cellulaire. Recemment, la detection basee sur la resonance des plasmons de surface (SPR) a ete appliquee a l'etude de reponses cellulaires. Cette methode de detection, permettant d'observer des variations d'indice de refraction associes a de faibles changements de masse a la surface d'un metal, a l'avantage de permettre l'etude d'une population de cellules vivantes en temps reel, sans necessiter l'introduction d'agents de marquage. Pour effectuer la detection au niveau de cellules individuelles, on peut employer la microscopie SPR, qui consiste a localiser spatialement la detection par un systeme d'imagerie. Cependant, la detection basee sur la SPR est une mesure sans marquage et les signaux mesures sont attribues a une reponse moyennee des differentes sources cellulaires. Afin de mieux comprendre et identifier les composantes cellulaires generant le signal mesure en SPR, il est pertinent de combiner la microscopie SPR avec une modalite complementaire, soit l'imagerie de fluorescence. C'est dans cette problematique que s'insere ce projet de these, consistant a concevoir deux plates-formes distinctes de microscopie SPR et de fluorescence optimisees pour l'etude cellulaire, de sorte a evaluer les possibilites d'integration de ces deux modalites en un seul systeme. Des substrats adaptes pour chaque plate-forme ont ete concus et realises. Ces substrats employaient une couche d'argent passivee par l'ajout d'une mince couche d'or. La stabilite et la biocompatibilite des substrats ont ete validees pour l'etude cellulaire. Deux configurations permettant d'ameliorer la sensibilite en sondant les cellules plus profondement ont ete evaluees, soit l'emploi de plasmons de surface a longue portee et de guides d'onde a gaine metallique. La sensibilite accrue de ces

  3. Formulation, caracterisation, modelisation et prevision du comportement thermomecanique des pieces plastiques et composites de fibres de bois : Application aux engrenages =

    NASA Astrophysics Data System (ADS)

    Mijiyawa, Faycal

    Cette etude permet d'adapter des materiaux composites thermoplastiques a fibres de bois aux engrenages, de fabriquer de nouvelles generations d'engrenages et de predire le comportement thermique de ces engrenages. Apres une large revue de la litterature sur les materiaux thermoplastiques (polyethylene et polypropylene) renforces par les fibres de bois (bouleau et tremble), sur la formulation et l'etude du comportement thermomecanique des engrenages en plastique-composite; une relation a ete etablie avec notre presente these de doctorat. En effet, beaucoup d'etudes sur la formulation et la caracterisation des materiaux composites a fibres de bois ont ete deja realisees, mais aucune ne s'est interessee a la fabrication des engrenages. Les differentes techniques de formulation tirees de la litterature ont facilite l'obtention d'un materiau composite ayant presque les memes proprietes que les materiaux plastiques (nylon, acetal...) utilises dans la conception des engrenages. La formulation des materiaux thermoplastiques renforces par les fibres de bois a ete effectuee au Centre de recherche en materiaux lignocellulosiques (CRML) de l'Universite du Quebec a Trois-Rivieres (UQTR), en collaboration avec le departement de Genie Mecanique, en melangeant les composites avec deux rouleaux sur une machine de type Thermotron-C.W. Brabender (modele T-303, Allemand) ; puis des pieces ont ete fabriquees par thermocompression. Les thermoplastiques utilises dans le cadre de cette these sont le polypropylene (PP) et le polyethylene haute densite (HDPE), avec comme renfort des fibres de bouleau et de tremble. A cause de l'incompatibilite entre la fibre de bois et le thermoplastique, un traitement chimique a l'aide d'un agent de couplage a ete realise pour augmenter les proprietes mecaniques des materiaux composites. Pour les composites polypropylene/bois : (1) Les modules elastiques et les contraintes a la rupture en traction des composites PP/bouleau et PP/tremble evoluent

  4. Etude des aspects cliniques, échographiques et nutritionnels du syndrome des ovaires micropolykystiques (SOMPK) à Mbuji-Mayi, RD du Congo

    PubMed Central

    Kalenda, Louis Mbuyamba Ntobo; Mikenji, Justin Biayi; Nkoy, Albert Mwembo-Tambwe; Kayamba, Prosper Kalenga Muenze

    2014-01-01

    Introduction Le Syndrome des Ovaires Micropolykystiques (SOMPK) est polymorphe. L'objectif de cette étude était de déterminer la prévalence et rechercher les facteurs nutritionnels éventuellement associés. Méthodes Chez 300 patientes atteintes de SOMPK faisant l'objet de cette étude, les données anamnestiques, cliniques et échographiques, et les habitudes alimentaires ont été analysées. Les statistiques usuelles et les mesures d'association ont été utilisées pour analyser les résultats. Résultats La prévalence de SOMPK était de 23,6%. L’âge moyen des patientes avec SOMPK était 24 ± 7 ans et chez celles sans SOMPK 36 ± 7 ans (P < 0,05). Le risque de développer le SOMPK en présence d'un niveau de vie élevé était de 2,03 (RR = 2,03; IC à 95%: 1,73-2,38; P = 0,00). Le risque de développer le SOMPK en exerçant une activité légère est de 2,15 (RR = 2,15; IC à 95%: 1,87-2,87; P= 0,00). La proportion des patientes avec SOMPK ayant accumulé plus de 2400 kcal était de 59% vs 36% (P < 0,05) et le risque de développer le SOMPK lorsque l’énergie accumulée était supérieure à 2400 kcal était de 1,57 (RR = 1,57; IC à 95%: 1,33-1,85; P= 0,00). Conclusion Dans notre milieu la prévalence de SOMPK était de 23,6%. Les facteurs associés au SOMPK étaient l’âge, l’énergie accumulée de plus de 2400 Kcal, le niveau socio-économique élevé et l'activité physique légère. Des études analytiques plus poussées sont nécessaires, pour évaluer la force du risque que représentent ces différents facteurs étudiés. PMID:25870722

  5. Etudes des Reactions de Transfert LITHIUM-7/LITHIUM -6

    NASA Astrophysics Data System (ADS)

    Baddou, Djafer

    Les reactions de transfert de deux nucleons ^7Li/^6Li(^3He, rm p)^8Be/^9Be ont ete effectuees a partir d'um faisceau d'^3He initialement polarise et d'energie incidente egale a 4.58 MeV au centre de la cible. Le faisceau d'^3He est simplement ionise et il est accelere par l'accelerateur Van de Graaff de l'Universite Laval. Ce faisceau d' ^3He est de polarisation egale a 40% et il est obtenu a partir d'une source d'^3He a l'etat metastable. Nous avons decrit la reaction depuis la production et le transport du faisceau initial de l'^3 He jusqu'a la chambre de reaction. Par la suite, nous avons obtenu les distributions angulaires de la section efficace differentielle et du pouvoir d'analyse de ces reactions. Elles ont ete comparees a la theorie DWBA a l'approximation zero. La theorie a montre qu'il s'agit d'un transfert de deux particules independants (neutron, proton) pour le cas de la reaction ^7Li( ^3He,rm p)^9Be et d'un transfert de "cluster" deuteron pour le cas de la reaction ^6Li(^3He, rm p)^8Be. Notons que pour cette reaction l'instabilite du ^8Be ne nous permet pas d'avoir une diffusion elastique permettant la determination des parametres du modele optique entre ce noyau et la particule diffusee. Afin de contourner cette difficulte, nous supposons que le ^8 Be est un noyau compose de deux particules alpha et nous avons teste cette hypothese avec les reactions ^6Li(^3He, rm p)^8Be et ^7Li( ^3He,rm d)^8Be. Nous mentionnons a la fin que nous avons observe que l'etat fondamental de la reaction ^6Li( ^3He,rm p)^8Be et l'etat excite 2.43 MeV de la reaction ^7Li(^3He,rm p)^9Be sont des reactions directes alors que le premier etat excite (2.96 MeV) de la reaction ^6Li(^3He,rm p)^8Be et l'etat fondamental de la reaction ^7Li(^3He,rm p)^9Be peuvent etre domines par une reaction a noyau compose.

  6. Conception d'un outil d'aide a la decision de technologies de fabrication additive en milieu aeronautique

    NASA Astrophysics Data System (ADS)

    Buvat, Gael

    La fabrication additive offre une opportunite d'amelioration des methodes de productions de pieces. Cependant, les technologies de fabrication additive sont diverses, les fournisseurs de services sont multiples et peu de personnel est forme pour operer sur ces technologies. L'objectif de cette etude est d'emettre une suggestion de concepts d'outils d'aide a la decision de technologies, de materiaux et de post-traitements de fabrication additive en milieu aeronautique. Trois sous-objectifs sont employes. Premierement, la definition des criteres de decision de technologies, de materiaux et de post-traitements de fabrication additive. Ensuite, l'elaboration d'un cahier des charges de l'outil d'aide a la decision en accord avec les besoins industriels du secteur aeronautique. Et enfin, la suggestion de trois concepts d'outils d'aide a la decision et leur evaluation par comparaison au cahier des charges etabli. Les criteres captures aupres de 11 industriels concernent des criteres de couts, de qualite, de conception et de delai d'obtention. Ensuite, nous avons elabore un cahier des charges permettant de reunir les besoins des industriels du secteur aeronautique selon trois axes qui constituent la colonne vertebrale des outils d'aide a la decision : une suggestion d'interface utilisateur, une suggestion de bases de donnees et un moteur de selection des technologies, des materiaux et des post-traitements de fabrication additive. La convivialite de l'interface utilisateur, l'evaluation de la qualite souhaitee par l'utilisateur et la prise en compte des etudes de cas realisees par le moteur de selection sont exemples de besoins que nous avons identifie au sein de cette etude. Nous avons ensuite transcrit ces besoins en specifications techniques pour permettre une evaluation du niveau de satisfaction des industriels au travers d'un pointage des trois concepts suggeres. Ces trois concepts d'outils d'aide a la decision ont ete realises respectivement grâce a Microsoft Excel

  7. Fabrication et caracterisation de nanocristaux de silicium localises, realises par gravure electrochimique pour des applications nanoelectroniques

    NASA Astrophysics Data System (ADS)

    Ayari-Kanoun, Asma

    Ce travail de these porte sur le developpement d'une nouvelle approche pour la localisation et l'organisation de nanocristaux de silicium realises par gravure electrochimique. Cette derniere represente une technique simple et peu couteuse par rapport aux autres techniques couramment utilisees pour la fabrication de nanocristaux de silicium. L'idee de ce travail a ete d'etudier la nanostructuration de minces couches de nitrure de silicium, d'environ 30 nm d'epaisseur pour permettre par la suite un arrangement periodique des nanocristaux de silicium. Cette pre-structuration est obtenue de facon artificielle en imposant un motif periodique via une technique de lithographie par faisceau d'electrons combinee avec une gravure plasma. Une optimisation des conditions de lithographie et de gravure plasma ont permis d'obtenir des reseaux de trous de 30 nm de diametre debouchant sur le silicium avec un bon controle de leur morphologie (taille, profondeur et forme). En ajustant les conditions de gravure electrochimique (concentration d'acide, temps de gravure et densite de courant), nous avons obtenu des reseaux -2D ordonnes de nanocristaux de silicium de 10 nm de diametre a travers ces masques de nanotrous avec le controle parfait de leur localisation, la distance entre les nanocristaux et leur orientation cristalline. Des etudes electriques preliminaires sur ces nanocristaux ont permis de mettre en evidence des effets de chargement. Ces resultats tres prometteurs confirment l'interet des nanocristaux de silicium realises par gravure electrochimique dans le futur pour la fabrication a grande echelle de dispositifs nanoelectroniques. Mots-cles : localisation, organisation, nanocristaux de silicium, gravure electrochimique, lithographie electronique, gravure plasma, nitrure de silicium.

  8. Symetrie en energie des spectres de l'onde de densite de charge dans le 2-hydrogene seleniure de niobium

    NASA Astrophysics Data System (ADS)

    Behmand, Behnaz

    Les mecanismes qui menent a la supraconductivite dans les supraconducteurs a haute temperature critique sont encore aujourd'hui mal compris contrairement a ceux dans les supraconducteurs conventionnels. Dans les hauts-Tc, certaines modulations de la densite d'etats electroniques coexistant avec la phase supraconductrice ont ete observees, ce qui engendre des questionnements sur leur role dans la supraconductivite. En fait, plusieurs types de modulation de la densite d'etats electroniques existent, comme par exemple l'onde de densite de charge et l'onde de densite de paires. Ces deux modulations, d'origines differentes et mesurables avec la technique de spectroscopie par effet tunnel, peuvent etre differenciees avec une etude de leur symetrie. Ce memoire consistera donc a presenter l'etude de la symetrie de l'onde de densite de charge dans le 2H-NbSe2 qui est presente dans la phase supraconductrice a 300 mK. Par contre, certaines difficultes liees au principe de mesure, soit l'effet de normalisation, nuisent a l'identification de cette symetrie. La methode, pour contourner ce probleme sera alors l'element clef de ce travail.

  9. Developpement d'un modele analytique pour l'analyse en elasticite lineaire de champs de deformation et contrainte au sein d'un polycristal. comparaison avec la methode des elements finis =

    NASA Astrophysics Data System (ADS)

    Bretin, Remy

    L'endommagement par fatigue des materiaux est un probleme courant dans de nombreux domaines, dont celui de l'aeronautique. Afin de prevenir la rupture par fatigue des materiaux il est necessaire de determiner leur duree de vie en fatigue. Malheureusement, dues aux nombreuses heterogeneites presentes, la duree de vie en fatigue peut fortement varier entre deux pieces identiques faites dans le meme materiau ayant subi les memes traitements. Il est donc necessaire de considerer ces heterogeneites dans nos modeles afin d'avoir une meilleure estimation de la duree de vie des materiaux. Comme premiere etape vers une meilleure consideration des heterogeneites dans nos modeles, une etude en elasticite lineaire de l'influence des orientations cristallographiques sur les champs de deformations et de contraintes dans un polycristal a ete realisee a l'aide de la methode des elements finis. Des correlations ont pu etre etablies a partir des resultats obtenus, et un modele analytique en elasticite lineaire prenant en compte les distributions d'orientations cristallographiques et les effets de voisinage a pu etre developpe. Ce modele repose sur les bases des modeles d'homogeneisation classique, comme le schema auto-coherent, et reprend aussi les principes de voisinage des automates cellulaires. En prenant pour reference les resultats des analyses elements finis, le modele analytique ici developpe a montre avoir une precision deux fois plus grande que le modele auto-coherent, quel que soit le materiau etudie.

  10. Etude de l'affaiblissement du comportement mecanique du pergelisol du au rechauffement climatique

    NASA Astrophysics Data System (ADS)

    Buteau, Sylvie

    Le rechauffement climatique predit pour les prochaines decennies, aura des impacts majeurs sur le pergelisol qui sont tres peu documentes pour l'instant. La presente etude a pour but d'evaluer ces impacts sur les proprietes mecaniques du pergelisol et sa stabilite a long terme. Une nouvelle technique d'essai de penetration au cone a taux de deformation controle, a ete developpee pour caracteriser en place le pergelisol. Ces essais geotechniques et la mesure de differentes proprietes physiques ont ete effectues sur une butte de pergelisol au cours du printemps 2000. Le developpement et l'utilisation d'un modele geothermique 1D tenant compte de la thermodependance du comportement mecanique ont permis d'evaluer que les etendues de pergelisol chaud deviendraient instables a la suite d'un rechauffement de l'ordre de 5°C sur cent ans. En effet, la resistance mecanique du pergelisol diminuera alors rapidement jusqu'a 11,6 MPa, ce qui correspond a une perte relative de 98% de la resistance par rapport a un scenario sans rechauffement.

  11. Methodes d'amas quantiques a temperature finie appliquees au modele de Hubbard

    NASA Astrophysics Data System (ADS)

    Plouffe, Dany

    Depuis leur decouverte dans les annees 80, les supraconducteurs a haute temperature critique ont suscite beaucoup d'interet en physique du solide. Comprendre l'origine des phases observees dans ces materiaux, telle la supraconductivite, est l'un des grands defis de la physique theorique du solide des 25 dernieres annees. L'un des mecanismes pressentis pour expliquer ces phenomenes est la forte interaction electron-electron. Le modele de Hubbard est l'un des modeles les plus simples pour tenir compte de ces interactions. Malgre la simplicite apparente de ce modele, certaines de ses caracteristiques, dont son diagramme de phase, ne sont toujours pas bien etablies, et ce malgre plusieurs avancements theoriques dans les dernieres annees. Cette etude se consacre a faire une analyse de methodes numeriques permettant de calculer diverses proprietes du modele de Hubbard en fonction de la temperature. Nous decrivons des methodes (la VCA et la CPT) qui permettent de calculer approximativement la fonction de Green a temperature finie sur un systeme infini a partir de la fonction de Green calculee sur un amas de taille finie. Pour calculer ces fonctions de Green, nous allons utiliser des methodes permettant de reduire considerablement les efforts numeriques necessaires pour les calculs des moyennes thermodynamiques, en reduisant considerablement l'espace des etats a considerer dans ces moyennes. Bien que cette etude vise d'abord a developper des methodes d'amas pour resoudre le modele de Hubbard a temperature finie de facon generale ainsi qu'a etudier les proprietes de base de ce modele, nous allons l'appliquer a des conditions qui s'approchent de supraconducteurs a haute temperature critique. Les methodes presentees dans cette etude permettent de tracer un diagramme de phase pour l'antiferromagnetisme et la supraconductivite qui presentent plusieurs similarites avec celui des supraconducteurs a haute temperature. Mots-cles : modele de Hubbard, thermodynamique

  12. Polarization studies on zinc in hydrochloric acid solution containing some organic solvents

    NASA Astrophysics Data System (ADS)

    Mohamed, A. K.

    1999-05-01

    The corrosion behaviour of zinc metal in some organic solvents was tested electrochemically using galvanometric polarization measurements. The results showed that the studied organic solvents act as mixed type inhibitors. The inhibition was assumed to occur via physical adsorption of the inhibitor molecules fitting a Temkin's isotherm. The inhibition eficiency of the solvents increase in the order: glycerol>ethylene glycol>DMSO>dioxane. This order is not affected by the variation in temperature in the range 35-55 circC. The increase in temperature was found to increase the corrosion in absence and in presence of inhibitors. Some thermodynamic parameters for adsorption were also computed and discussed. Le comportement de corrosion du zinc métallique dans certains solvants organiques a été testé électrochimiquement en utilisant les mesures de polarisation galvanométrique. Les résultats ont montré que les solvants organiques étudiés agissent comme des inhibiteurs de type mixte. L'inhibition semble se produire par l'adsorption physique des molécules inhibitrices selon une isotherme de Temkin. L'efficacité d'inhibition des solvants augmente dans l'ordre suivant : glycérol>éthylène glycol>DMSO>dioxane. Cet ordre n'est pas affecté par une variation de température dans l'intervalle compris entre 35 et 55 circC. La corrosion augmente avec la température, en absence ou en présence d'inhibiteurs. Certains paramètres thermodynamiques d'adsorption ont été calculés et discutés.

  13. Fabrication par injection flexible de pieces coniques pour des applications aerospatiales

    NASA Astrophysics Data System (ADS)

    Shebib Loiselle, Vincent

    Les materiaux composites sont presents dans les tuyeres de moteurs spatiaux depuis les annees soixante. Aujourd'hui, l'avenement des tissus tridimensionnels apporte une solution innovatrice au probleme de delamination qui limitait les proprietes mecaniques de ces composites. L'utilisation de ces tissus necessite toutefois la conception de procedes de fabrication mieux adaptes. Une nouvelle methode de fabrication de pieces composites pour des applications aerospatiales a ete etudiee tout au long de ce travail. Celle-ci applique les principes de l'injection flexible (procede Polyflex) a la fabrication de pieces coniques de fortes epaisseurs. La piece de validation a fabriquer represente un modele reduit de piece de tuyere de moteur spatial. Elle est composee d'un renfort tridimensionnel en fibres de carbone et d'une resine phenolique. La reussite du projet est definie par plusieurs criteres sur la compaction et la formation de plis du renfort et sur la formation de porosites de la piece fabriquee. Un grand nombre d'etapes ont ete necessaires avant la fabrication de deux pieces de validation. Premierement, pour repondre au critere sur la compaction du renfort, la conception d'un outil de caracterisation a ete entreprise. L'etude de la compaction a ete effectuee afin d'obtenir les informations necessaires a la comprehension de la deformation d'un renfort 3D axisymetrique. Ensuite, le principe d'injection de la piece a ete defini pour ce nouveau procede. Pour en valider les concepts proposes, la permeabilite du renfort fibreux ainsi que la viscosite de la resine ont du etre caracterisees. A l'aide de ces donnees, une serie de simulations de l'ecoulement pendant l'injection de la piece ont ete realisees et une approximation du temps de remplissage calculee. Apres cette etape, la conception du moule de tuyere a ete entamee et appuyee par une simulation mecanique de la resistance aux conditions de fabrication. Egalement, plusieurs outillages necessaires pour la fabrication

  14. Actes du colloque sur le bilinguisme, Universite de Neuchatel, 14/15 Septembre, 1981 (Proceedings of the Colloquium on Bilingualism, University of Neuchatel, September 14-15, 1981).

    ERIC Educational Resources Information Center

    TRANEL, 1982

    1982-01-01

    This issue contains proceedings of a colloquium on linguistics at the University of Neuchatel: (1) "Propositions epistemologiques pour une etude du bilinguisme (Epistemological Propositions for a Study of Bilingualism)," by B. Py; (2) "Comment on di ca? Prolegomenes a une etude de la composante semantique du langage des migrants (How Do You Say…

  15. Singing as a Therapeutic Agent, inThe Etude, 1891-1949.

    PubMed

    Hunter

    1999-01-01

    The Etude music magazine, founded by Theodore Presser, was one of a number of popular music magazines published in the years prior to the establishment of the music therapy profession in 1950. During its publication run from 1883 to 1957, over 100 music therapy related articles appeared, including 13 on the health benefits of singing published between 1891 and 1949. Written by authors with diverse backgrounds, such as the famous Battle Creek, Michigan physician John Harvey Kellogg and Boston music critic Louis C. Elson, the articles contained consistent and adamant support regarding the health benefits of singing. The advantages described were both physical and psychological, and were recommended prophylactically for well persons and therapeutically for ill persons. Although the articles varied in perspective, from philosophical to theoretical to pedagogical, there is a consistent holistic medicine theme that appeared almost ahead of its time and no doubt linked to the push for vocal music education in that era. The importance of The Etude in promulgating ideas that helped shape the early practice of music therapy should not be underestimated. For much of its publication run The Etude was the largest music periodical in print, reaching its peak circulation of 250,000 copies per month in 1924.

  16. Modelisation de la Propagation des Ondes Sonores dans un Environnement Naturel Complexe

    NASA Astrophysics Data System (ADS)

    L'Esperance, Andre

    Ce travail est consacre a la propagation sonore a l'exterieur dans un environnement naturel complexe, i.e. en presence de conditions reelles de vent, de gradient de temperature et de turbulence atmospherique. Plus specifiquement ce travail comporte deux objectifs. D'une part, il vise a developper un modele heuristique de propagation sonore (MHP) permettant de prendre en consideration l'ensemble des phenomenes meteorologiques et acoustiques influencant la propagation du son a l'exterieur. D'autre part, il vise a identifier dans quelles circonstances et avec quelle importance les conditions meteorologiques interviennent sur la propagation sonore. Ce travail est divise en cinq parties. Apres une breve introduction identifiant les motivations de cette etude (chapitre 1), le chapitre 2 fait un rappel des travaux deja realises dans le domaine de la propagation du son a l'exterieur. Ce chapitre presente egalement les bases de l'acoustique geometrique a partir desquelles ont ete developpees la partie acoustique du modele heuristique de propagation. En outre, on y decrit comment les phenomenes de refraction et de turbulence atmospherique peuvent etre consideres dans la theorie des rayons. Le chapitre 3 presente le modele heuristique de propagation (MHP) developpe au cours de cet ouvrage. La premiere section de ce chapitre decrit le modele acoustique de propagation, modele qui fait l'hypothese d'un gradient de celerite lineaire et qui est base sur une solution hybride d'acoustique geometrique et de theorie des residus. La deuxieme section du chapitre 3 traite plus specifiquement de la modelisation des aspects meteorologiques et de la determination des profils de celerite et des index de fluctuation associes aux conditions meteorologiques. La section 3 de ce chapitre decrit comment les profils de celerite resultants sont linearises pour les calculs dans le modele acoustique, et finalement la section 4 donne les tendances generales obtenues par le modele. Le chapitre 4 decrit

  17. Study of the Tributyl Phosphate--30 Percent Dodecane Solvent; ETUDE DU SOLVANT PHOSPHATE TRIBUTYLIQUE 30 PERCENT--DODECANE (in French)

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Leroy, P.

    1967-07-01

    This study, originating mainly from a literature survey, gives the principal chemical and physical features of the tributyl-phosphate (TBP) agent diluted at 30 volumes per cent in dodecane. The mixture is a very commonly used extractant in nuclear fuel processing. In this paper, the main following points are reported: -) the components (TBP and diluents) -) the TBP-diluents systems (non-loaded), -) the TBP-diluents-water systems, -) TBP-diluents-water-nitric acid systems, and -) industrial solvents. (author) [French] Cette etude, d'origine bibliographique, regroupe les caracteristiques physico-chimiques essentielles du phosphate tributylique (TBP) dilue a 30% en volume dans du dodecane. Ce melange constitue un agentmore » d'extraction tres utilise dans le traitement des combustibles nucleaires. Les principaux points traites sont les suivants: -) les constituants (TBP et diluants), -) les systemes TBP-diluants non charges, -) les systemes TBP-diluants-eau, -) les systemes TBP-diluants-eau-acide nitrique, et -) les solvants industriels. (auteur)« less

  18. Zinc electrode and rechargeable zinc-air battery

    DOEpatents

    Ross, Jr., Philip N.

    1989-01-01

    An improved zinc electrode is disclosed for a rechargeable zinc-air battery comprising an outer frame and a porous foam electrode support within the frame which is treated prior to the deposition of zinc thereon to inhibit the formation of zinc dendrites on the external surface thereof. The outer frame is provided with passageways for circulating an alkaline electrolyte through the treated zinc-coated porous foam. A novel rechargeable zinc-air battery system is also disclosed which utilizes the improved zinc electrode and further includes an alkaline electrolyte within said battery circulating through the passageways in the zinc electrode and an external electrolyte circulation means which has an electrolyte reservoir external to the battery case including filter means to filter solids out of the electrolyte as it circulates to the external reservoir and pump means for recirculating electrolyte from the external reservoir to the zinc electrode.

  19. Detection de la fin de la compaction des anodes par le son

    NASA Astrophysics Data System (ADS)

    Sanogo, Bazoumana

    ete le lieu de tests finaux a l'usine en fabriquant des anodes avec differents criteres (variation du temps de compaction, taux de brai, arret manuel du compacteur, variation de la pression des ballons du haut du compacteur). Ces anodes ont ete ensuite analysees au laboratoire a l'UQAC. En parallele a ces travaux precites, l'amelioration de l'application d'analyse du son a ete faite avec le choix des parametres d'analyse et leur standardisation. Les resultats des premiers tests au laboratoire et ceux de la campagne de juin 2014 ont montre que la formation des anodes se fait suivant trois etapes : rearrangement des particules et du brai, compaction et consolidation et enfin la finition. Ces travaux ont montre en outre que le temps de compaction joue un role tres important dans la definition des proprietes finales des anodes. Ainsi, en plus du type de brai, du taux de brai et du type de coke, il faut tenir compte du temps de sur-compaction et de sous-compaction. En effet, ceci a ete demontre a travers les deux validations qui ont ete realisees. Les resultats de la caracterisation des echantillons (venant des anodes de la campagne de decembre 2015) ont montre qu'une anode compactee a un temps optimal acquiert une bonne resistance a la compression et sa resistivite electrique baisse. En outre, on note que le temps de compaction dans notre cas a baisse legerement avec l'augmentation de la pression des ballons de haut du vibrocompacteur. Ce qui a eu pour effet d'augmenter la densite crue de l'anode. Toutefois, il faut s'abstenir de generaliser ce constat car le nombre d'anodes testees est faible dans notre cas. Par ailleurs, cette etude montre que le temps necessaire pour le formage d'une anode croit avec l'augmentation du taux de brai et baisse legerement avec l'augmentation de la pression des ballons. (Abstract shortened by ProQuest.).

  20. Etude des phenomenes chimiques au contact entre le bloc cathodique et la barre collectrice d'une cellule d'electrolyse d'aluminium

    NASA Astrophysics Data System (ADS)

    Lebeuf, Martin

    La production d'aluminium est une industrie importante au Québec. Les propriétés de ce métal le vouent à de multiples usages présents et futurs dans le cadre d'une économie moderne durable. Toutefois, le procédé Hall-Héroult est très énergivore et des progrès demeurent donc nécessaires pour en diminuer les coûts financiers et environnementaux. Parmi les améliorations envisageables de la cellule d'électrolyse se trouve le contact entre la cathode et la barre collectrice, qui doit offrir une faible résistivité au passage du courant électrique. En cours d'opération de la cellule, ce contact a tendance à se dégrader, générant des pertes énergétiques significatives. Les causes de cette dégradation, pouvant provenir de phénomènes chimiques, thermiques, mécaniques et/ou électriques, demeurent mal comprises. Le but du présent projet était donc d'étudier les phénomènes chimiques se produisant au contact bloc-barre de la cellule d'électrolyse Hall-Héroult. En premier lieu, un aspect crucial à considérer est la pénétration du bain électrolytique dans la cathode, car des composés de bain atteignent éventuellement la barre collectrice et peuvent y réagir. A cet effet, une méthode novatrice a été développée afin d'étudier les cathodes et la pénétration du bain dans celles-ci à l'aide de la microtomographie à rayons X. Cette méthode rapide et efficace s'est avérée fort utile dans le projet et a un potentiel important pour l'étude future des cathodes et des phénomènes qui s'y produisent. Ensuite, une cellule d'électrolyse rectangulaire à petite échelle a été développée. Plusieurs phénomènes observés 'en industrie sur des autopsies de cellules post-opération et rapportés dans la littérature ont été reproduis avec succès à l'aide de cette cellule expérimentale. Puis, des tests sans électrolyse, ciblant l'effet du bain électrolytique sur l'acier, ont aussi été conçus et complétés afin de s

  1. A New Approach to Electrical Characterization of Exploding Foil Initiators

    DTIC Science & Technology

    1998-12-01

    processed to illustrate the methodology. RESUME Dans une etude precedente de 1a caracterisation electrique des detonateurs a element projete (DEP), on a...applicable a 1a caracterisation electrique des DEP et decrit la methodologie experimentale adequate. Cette methodologie est illustree par la

  2. Etude des facteurs de risque du retard de croissance intra-utérin à Lubumbashi

    PubMed Central

    Moyambe, Jules Ngwe Thaba; Bernard, Pierre; Khang'Mate, Faustin; Nkoy, Albert Mwembo Tambwe A; Mukalenge, Faustin Chenge; Makanda, Daudet; Twite, Eugene; Ndudula, Arthur Munkana; Lubamba, Cham; Kadingi, Arnauld Kabulu; Kayomb, Mutach; Kayamba, Prosper Kalenga Muenze

    2013-01-01

    Introduction Dans notre milieu, il n'existe aucune politique de prévention du Retard de Croissance Intra-Utérin (RCIU) clairement défini. L'objectif de ce travail était d'identifier les facteurs de risque de RCIU afin de proposer une stratégie de lutte contre cette pathologie en agissant surtout sur des facteurs pouvant faire l'objet d'une action préventive. Méthodes Une étude cas-témoins a été menée dans 11 centres hospitaliers de Lubumbashi en République Démocratique du Congo, de Janvier 2010 à Juin 2011, dans le but d'identifier les facteurs de risque du retard de croissance intra-utérin (RCIU). Au total 420 gestantes (cas et témoins) avec grossesse monofoetale d'au moins 24 semaines d'aménorrhée ont été inclues dans l'étude. Les cas correspondaient aux gestantes dont le poids du fœtus était resté inférieur au 10 eme percentile des courbes de référence d'Alexander, après 2 échographies successives réalisées à intervalle de 4 semaines. Les témoins correspondaient aux gestantes dont le poids du fœtus était supérieur ou égal au 10 eme percentile de mêmes courbes. A chaque cas a été apparié un témoin de même parité porteur d'une grossesse de même âge. Résultats L'analyse univariée a identifié comme facteurs de risque: la taille maternelle. Conclusion L'amélioration du niveau socio-économique des populations, la lutte contre le paludisme et les consultations prénatales mieux organisées couplées à une meilleure éducation sanitaire et nutritionnelle peuvent contribuer sensiblement à la réduction de la fréquence du RCIU à Lubumbashi. PMID:23504392

  3. Contribution a la comprehension de la durabilite a l'ecaillage des betons contenant de la cendre volante et du laitier

    NASA Astrophysics Data System (ADS)

    Houehanou, Ernesto C.

    L'incorporation des ajouts cimentaires dans le beton est connue pour ses avantages technologiques et environnementaux. Pour assurer une plus grande utilisation des ajouts cimentaires, il faut accroitre la connaissance dans ce domaine surtout les facteurs relatifs a la durabilite des ouvrages construits avec les betons contenant des ajouts mineraux. Jusqu'a present, la plupart des etudes sur les betons contenant de la cendre volante et du laitier semble s'accorder sur leur moins bonne durabilite a l'ecaillage surtout lorsqu'on les compare au beton ordinaire. Les raisons de cette moins bonne performance ne sont pas toutes connues et cela limite bien des fois l'incorporation de la cendre volante et de laitier dans le beton pour des ouvrages fortement exposes aux cycles de gel-degel en presence de sels fondants. Cette these vise la comprehension des problematiques de la durabilite a l'ecaillage des betons contenant des ajouts cimentaires tels la cendre volante et le laitier. Les objectifs sont de mieux comprendre la representativite et la severite relative des essais normalises ASTM C672 et NQ 2621-900 pour l'evaluation de la durabilite a l'ecaillage de ces betons, d'etudier l'influence de la methode de murissement sur la durabilite a l'ecaillage et d'etudier la relation entre la durabilite a l'ecaillage et la sorptivite des surfaces de beton ainsi que la particularite de la microstructure des betons contenant de la cendre volante. Cinq types de betons a air entraine contenant 25% et 35% de cendre volante et laitier ainsi que 1% et 2% de fumee de silice ont ete produits, muris selon differentes methodes et soumis a des essais acceleres selon les deux procedures normalisees ainsi qu'un essai de sorptivite. Les differentes methodes de murissement sont choisies de facon a mettre en evidence aussi bien l'influence des parametres des essais que celle de la methode de murissement elle-meme. La durabilite en laboratoire des betons testes a ete comparee avec celle de betons

  4. Zinc Absorption by Young Adults from Supplemental Zinc Citrate Is Comparable with That from Zinc Gluconate and Higher than from Zinc Oxide123

    PubMed Central

    Wegmüller, Rita; Tay, Fabian; Zeder, Christophe; Brnić, Marica; Hurrell, Richard F.

    2014-01-01

    The water-soluble zinc salts gluconate, sulfate, and acetate are commonly used as supplements in tablet or syrup form to prevent zinc deficiency and to treat diarrhea in children in combination with oral rehydration. Zinc citrate is an alternative compound with high zinc content, slightly soluble in water, which has better sensory properties in syrups but no absorption data in humans. We used the double-isotope tracer method with 67Zn and 70Zn to measure zinc absorption from zinc citrate given as supplements containing 10 mg of zinc to 15 healthy adults without food and compared absorption with that from zinc gluconate and zinc oxide (insoluble in water) using a randomized, double-masked, 3-way crossover design. Median (IQR) fractional absorption of zinc from zinc citrate was 61.3% (56.6–71.0) and was not different from that from zinc gluconate with 60.9% (50.6–71.7). Absorption from zinc oxide at 49.9% (40.9–57.7) was significantly lower than from both other supplements (P < 0.01). Three participants had little or no absorption from zinc oxide. We conclude that zinc citrate, given as a supplement without food, is as well absorbed by healthy adults as zinc gluconate and may thus be a useful alternative for preventing zinc deficiency and treating diarrhea. The more insoluble zinc oxide is less well absorbed when given as a supplement without food and may be minimally absorbed by some individuals. This trial was registered at clinicaltrials.gov as NCT01576627. PMID:24259556

  5. Zinc lozenges and the common cold: a meta-analysis comparing zinc acetate and zinc gluconate, and the role of zinc dosage.

    PubMed

    Hemilä, Harri

    2017-05-01

    To compare the efficacy of zinc acetate lozenges with zinc gluconate lozenges in common cold treatment and to examine the dose-dependency of the effect. Meta-analysis. Placebo-controlled zinc lozenge trials, in which the zinc dose was > 75 mg/day. The pooled effect of zinc lozenges on common cold duration was calculated by using inverse-variance random-effects method. Seven randomised trials with 575 participants with naturally acquired common colds. Duration of the common cold. The mean common cold duration was 33% (95% CI 21% to 45%) shorter for the zinc groups of the seven included trials. Three trials that used lozenges composed of zinc acetate found that colds were shortened by 40% and four trials that used zinc gluconate by 28%. The difference between the two salts was not significant: 12 percentage points (95% CI: -12 to + 36). Five trials used zinc doses of 80-92 mg/day, common cold duration was reduced by 33%, and two trials used zinc doses of 192-207 mg/day and found an effect of 35%. The difference between the high-dose and low-dose zinc trials was not significant: 2 percentage points (95% CI: -29 to + 32). Properly composed zinc gluconate lozenges may be as effective as zinc acetate lozenges. There is no evidence that zinc doses over 100 mg/day might lead to greater efficacy in the treatment of the common cold. Common cold patients may be encouraged to try zinc lozenges for treating their colds. The optimal lozenge composition and dosage scheme need to be investigated further.

  6. Profil bactériologique du pied diabétique et son impact sur le choix des antibiotiques

    PubMed Central

    Zemmouri, Adil; Tarchouli, Mohamed; Benbouha, Abdellatif; Lamkinsi, Tarik; Bensghir, Mustapha; Elouennass, Mostafa; Haimeur, Cherqui

    2015-01-01

    Introduction Analyse du profil bactériologique des pieds diabétiques pris en charge à l'hôpital militaire de Rabat et son influence sur l'antibiothérapie de première intention. Méthodes Etude prospective non randomisée étalée sur 18 mois, ayant concerné 105 patients. Après recueil des données et en attente des résultats bactériologiques nos patients ont été divisés en deux groupes: un groupe a été mis sous Amoxicilline + Acide clavulanique + Gentamycine (59 patients) et un groupe sous Ertapénème±Gentamycine (46 patients). Résultats L’étude a regroupé 85 hommes et 20 femmes (sexe ratio = 4.26). L’âge moyen est de 64.4 ans. La gangrène a été observée chez 79% des malades; elle était humide-donc surinfectée en principe- dans 43% des cas. Par ailleurs, 67% des malades ont un chiffre de globules blancs 12000 définissant une infection sévère. L'ostéolyse a été mise en évidence chez 27% de nos patients. Parmi les différentes techniques de prélèvements: 81% ont été profonds dont 21% de biopsie osseuse per opératoire et 14% de prélèvements combinés. 42% de ces prélèvements sont poly microbiens et 21% sont stériles. Les résultats bactériologiques viennent confirmer la prédominance des bactéries aérobies à Gram positif. Le taux de remplacement de l'Ertapénème est de 22% contre un taux de 50% pour l'Amoxiclav. Conclusion L'antibiothérapie ne doit être instaurée qu'en cas d'infection du pied diabétique diagnostiquée sur les critères cliniques établis par les consensus internationaux récents. Le respect des mesures de lutte contre la diffusion de la résistance bactérienne s'avère primordiale. PMID:27386024

  7. Dietary phytate, zinc and hidden zinc deficiency.

    PubMed

    Sandstead, Harold H; Freeland-Graves, Jeanne H

    2014-10-01

    Epidemiological data suggest at least one in five humans are at risk of zinc deficiency. This is in large part because the phytate in cereals and legumes has not been removed during food preparation. Phytate, a potent indigestible ligand for zinc prevents it's absorption. Without knowledge of the frequency of consumption of foods rich in phytate, and foods rich in bioavailable zinc, the recognition of zinc deficiency early in the illness may be difficult. Plasma zinc is insensitive to early zinc deficiency. Serum ferritin concentration≤20μg/L is a potential indirect biomarker. Early effects of zinc deficiency are chemical, functional and may be "hidden". The clinical problem is illustrated by 2 studies that involved US Mexican-American children, and US premenopausal women. The children were consuming home diets that included traditional foods high in phytate. The premenopausal women were not eating red meat on a regular basis, and their consumption of phytate was mainly from bran breakfast cereals. In both studies the presence of zinc deficiency was proven by functional responses to controlled zinc treatment. In the children lean-mass, reasoning, and immunity were significantly affected. In the women memory, reasoning, and eye-hand coordination were significantly affected. A screening self-administered food frequency questionnaire for office might help caregiver's identify patients at risk of zinc deficiency. Copyright © 2014 Elsevier GmbH. All rights reserved.

  8. Acute changes in cellular zinc alters zinc uptake rates prior to zinc transporter gene expression in Jurkat cells.

    PubMed

    Holland, Tai C; Killilea, David W; Shenvi, Swapna V; King, Janet C

    2015-12-01

    A coordinated network of zinc transporters and binding proteins tightly regulate cellular zinc levels. Canonical responses to zinc availability are thought to be mediated by changes in gene expression of key zinc transporters. We investigated the temporal relationships of actual zinc uptake with patterns of gene expression in membrane-bound zinc transporters in the human immortalized T lymphocyte Jurkat cell line. Cellular zinc levels were elevated or reduced with exogenous zinc sulfate or N,N,N',N-tetrakis(2-pyridylmethyl)ethylenediamine (TPEN), respectively. Excess zinc resulted in a rapid 44 % decrease in the rate of zinc uptake within 10 min. After 120 min, the expression of metallothionein (positive control) increased, as well as the zinc exporter, ZnT1; however, the expression of zinc importers did not change during this time period. Zinc chelation with TPEN resulted in a rapid twofold increase in the rate of zinc uptake within 10 min. After 120 min, the expression of ZnT1 decreased, while again the expression of zinc importers did not change. Overall, zinc transporter gene expression kinetics did not match actual changes in cellular zinc uptake with exogenous zinc or TPEN treatments. This suggests zinc transporter regulation may be the initial response to changes in zinc within Jurkat cells.

  9. Zinc Enzymes.

    ERIC Educational Resources Information Center

    Bertini, I.; And Others

    1985-01-01

    Discusses the role of zinc in various enzymes concerned with hydration, hydrolysis, and redox reactions. The binding of zinc to protein residues, properties of noncatalytic zinc(II) and catalytic zinc, and the reactions catalyzed by zinc are among the topics considered. (JN)

  10. Zinc

    MedlinePlus

    ... Using toothpastes containing zinc, with or without an antibacterial agent, appears to prevent plaque and gingivitis. Some ... is some evidence that zinc has some antiviral activity against the herpes virus. Low zinc levels can ...

  11. Traitements didactiques preventifs d'un type de conceptions erronees en sciences physiques chez des eleves du secondaire

    NASA Astrophysics Data System (ADS)

    Blondin, Andre

    Dans un contexte constructiviste, les connaissances anterieures d'un individu sont essentielles a la construction de nouvelles connaissances. Quelle qu'en soit la source (certaines de ces connaissances ont ete elaborees en classe, d'autres ont ete elaborees par interaction personnelle de l'individu avec son environnement physique et social), ces connaissances, une fois acquises, constituent les matieres premieres de l'elaboration des nouvelles conceptions de cet individu. Generalement, cette influence est consideree comme positive. Cependant, dans un milieu scolaire ou l'apprentissage de certaines conceptions enchassees dans un programme d'etudes et enterinees par l'ensemble d'une communaute est obligatoire, certaines connaissances anterieures peuvent entraver la construction des conceptions exigees par la communaute. La litterature abonde de tels exemples. Cependant, certaines connaissances anterieures, en soi tout a fait conformes a l'Heritage, peuvent aussi, parce qu'utilisees de facon non pertinente, entraver la construction d'une conception exigee par la communaute. Ici, la litterature nous donne peu d'exemples de ce type, mais nous en fournirons quelques-uns dans le cadre theorique, et ce sera un d'entre eux qui servira de base a nos propos. En effet, une grande proportion d'eleves inscrits a un cours de sciences physiques de la quatrieme secondaire, en reponse a un probleme deja solutionne durant l'annee et redonne lors d'un examen sommatif, "Pourquoi la Lune nous montre-t-elle toujours la meme face?", attribue principalement la cause de ce phenomene a la rotation de la Terre sur son axe. En tant que responsable de l'enseignement de ce programme d'etudes, plusieurs questions nous sont venues a l'esprit, entre autres, comment, dans un contexte constructiviste, est-il possible de reduire chez un eleve, l'impact de cette connaissance anterieure dans l'elaboration de la solution et ainsi prevenir la construction d'une conception erronee? Nous avons teste nos

  12. Etude microdosimetrique de l'influence des materiaux sur l'efficacite biologique d'une source d'iode-125

    NASA Astrophysics Data System (ADS)

    Taschereau, Richard

    Cette these concerne les implants permanents pour la prostate. Les isotopes employes, le 103Pd et l'125I, semblent produire les memes resultats cliniques: le premier a cause d'une radiation plus efficace et le second a cause de sa demi-vie plus longue. La recherche utilise le cadre theorique de la microdosimetrie et des simulations Monte Carlo. Elle propose d'employer le spectre d'ejection dans le calcul de l'efficacite; ce changement fait passer l'efficacite relative du 103Pd de 10% a 5%. Elle montre ensuite qu'il est possible d'ameliorer l'efficacite de la radiation de 125I par l'exploitation des rayons X caracteristiques de la capsule. Une source amelioree faite de molybdene et d'yttrium est donnee en exemple. Elle procure une radiation de 5--7% plus efficace, ce qui surclasse les deux sources existantes. Les applications ne se limitent pas au traitement de la prostate; le traitement du melanome oculaire et la curietherapie endovasculaire pourraient en beneficier.

  13. Stochastic Pseudo-Boolean Optimization

    DTIC Science & Technology

    2011-07-31

    Right-Hand Side,” 2009 IN- FORMS Annual Meeting, San Diego, CA, October 11-14, 2009. 113 References [1] A.-Ghouila-Houri. Caracterisation des matrices...Optimization, 10:7–21, 2005. [30] P. Camion. Caracterisation des matrices unimodulaires. Cahiers Centre Etudes Rech., 5(4), 1963. [31] P. Camion

  14. Proceedings from the DRG Seminar on Robotics in the Battlefield (31st) Held in Paris, France on 6-8 March 1991 (Acetes du 31ieme Seminaire sur la Robotique du Champ de Bataile)

    DTIC Science & Technology

    1992-06-01

    8217Energie.4romnique) et GIAT-Industries (Groupern.ent Indusrriei dles Armements Terrestres ) ant 6t retenus ensemble par la DAT / SEFT (Direction des...Armements Terrestres , Sections d’Erudes et Fabrications des Tilicommunications ) pour une ’Etude de concepts de robots d-~ combat". Cette t6tude de dix...d’identification des amis utiusable par los ongins terrestres . *La t6l~opdration des armes utilisera des proc~dds sp~cifiques, no reprenant qu’en p

  15. [Improvement in zinc nutrition due to zinc transporter-targeting strategy].

    PubMed

    Kambe, Taiho

    2016-07-01

    Adequate intake of zinc from the daily diet is indispensable to maintain health. However, the dietary zinc content often fails to fulfill the recommended daily intake, leading to zinc deficiency and also increases the risk of developing chronic diseases, particularly in elderly individuals. Therefore, increased attention is required to overcome zinc deficiency and it is important to improve zinc nutrition in daily life. In the small intestine, the zinc transporter, ZIP4, functions as a component that is essential for zinc absorption. In this manuscript, we present a brief overview regarding zinc deficiency. Moreover, we review a novel strategy, called "ZIP4-targeting", which has the potential to enable efficient zinc absorption from the diet. ZIP4-targeting strategy is possibly a major step in preventing zinc deficiency and improving human health.

  16. Improved zinc electrode and rechargeable zinc-air battery

    DOEpatents

    Ross, P.N. Jr.

    1988-06-21

    The invention comprises an improved rechargeable zinc-air cell/battery having recirculating alkaline electrolyte and a zinc electrode comprising a porous foam support material which carries the active zinc electrode material. 5 figs.

  17. Influence of DNA-methylation on zinc homeostasis in myeloid cells: Regulation of zinc transporters and zinc binding proteins.

    PubMed

    Kessels, Jana Elena; Wessels, Inga; Haase, Hajo; Rink, Lothar; Uciechowski, Peter

    2016-09-01

    The distribution of intracellular zinc, predominantly regulated through zinc transporters and zinc binding proteins, is required to support an efficient immune response. Epigenetic mechanisms such as DNA methylation are involved in the expression of these genes. In demethylation experiments using 5-Aza-2'-deoxycytidine (AZA) increased intracellular (after 24 and 48h) and total cellular zinc levels (after 48h) were observed in the myeloid cell line HL-60. To uncover the mechanisms that cause the disturbed zinc homeostasis after DNA demethylation, the expression of human zinc transporters and zinc binding proteins were investigated. Real time PCR analyses of 14 ZIP (solute-linked carrier (SLC) SLC39A; Zrt/IRT-like protein), and 9 ZnT (SLC30A) zinc transporters revealed significantly enhanced mRNA expression of the zinc importer ZIP1 after AZA treatment. Because ZIP1 protein was also enhanced after AZA treatment, ZIP1 up-regulation might be the mediator of enhanced intracellular zinc levels. The mRNA expression of ZIP14 was decreased, whereas zinc exporter ZnT3 mRNA was also significantly increased; which might be a cellular reaction to compensate elevated zinc levels. An enhanced but not significant chromatin accessibility of ZIP1 promoter region I was detected by chromatin accessibility by real-time PCR (CHART) assays after demethylation. Additionally, DNA demethylation resulted in increased mRNA accumulation of zinc binding proteins metallothionein (MT) and S100A8/S100A9 after 48h. MT mRNA was significantly enhanced after 24h of AZA treatment also suggesting a reaction of the cell to restore zinc homeostasis. These data indicate that DNA methylation is an important epigenetic mechanism affecting zinc binding proteins and transporters, and, therefore, regulating zinc homeostasis in myeloid cells. Copyright © 2016 Elsevier GmbH. All rights reserved.

  18. Method of capturing or trapping zinc using zinc getter materials

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Hunyadi Murph, Simona E.; Korinko, Paul S.

    2017-07-11

    A method of trapping or capturing zinc is disclosed. In particular, the method comprises a step of contacting a zinc vapor with a zinc getter material. The zinc getter material comprises nanoparticles and a metal substrate.

  19. Radiolocation Techniques (Les Techniques de Radiolocalisation

    DTIC Science & Technology

    1992-11-01

    Dr R. Klemm DrD Rother FGAN- FFM SEL/LS/E Neuenahrer Strasse 20 Lorenzstrasse 10 D-5307 Wachtberg 7 D-7000 Stuttgart 40 Germany Germany Prof. G...des solutions. accas I lFionograinme, donc: aui profil. Cat article rapporte tine partie des Etudes mendes an La indthodo proposde s’inspirc de cette

  20. Mesure Objective De L'attenuation et De L'effet D'occlusion Des Protecteurs Auditifs a Partir Des Potentiels Evoques Stationnaires et Multiples =

    NASA Astrophysics Data System (ADS)

    Valentin, Olivier

    'environnement de travail et dont le confort est optimise permettrait, sur le long terme, d'ameliorer les conditions des travailleurs en minimisant le risque lie a la degradation de leur appareil auditif. Les perspectives de travail proposees a la fin de cette these consistent principalement a : (i) exploiter ces deux methodes avec une gamme frequentielle plus etendue, (ii) explorer la variabilite intra-individuelle de chacune des methodes, (iii) comparer les resultats des deux methodes avec ceux obtenus par l'intermediaire de la methode "Microphone in Real Ear" (MIRE) et (iv) verifier la compatibilite de chacune des methodes avec tous les types de protecteurs auditifs. De plus, pour la methode de mesure de l'effet d'occlusion utilisant les PEASM, une etude complementaire est necessaire pour lever la contradiction observee a 250 Hz.

  1. HBA1c: clinical and biological agreement for standardization of assay methods. Report by the experts of ALFEDIAM (Association de Langue Française pour lEtude du Diabète et des Maladies Métabolique) and SFBC (Société Française de Biologie Clinique).

    PubMed

    Gillery, P; Bordas-Fonfrède, M; Chapelle, J P; Drouin, P; Hue, G; Lévy-Marchal, C; Périer, C; Sélam, J L; Slama, G; Thivolet, C; Vialettes, B

    1999-09-01

    Glycohaemoglobin, and particularly haemoglobin A1c(HbA1c), assays have been used for many years to retrospectively evaluate the glycaemic control of diabetic patients. Cut-off values have been established for deciding treatment modifications. The techniques used in the laboratories however exhibit varying quality, and all of them are not yet standardized. The consequence is an under-utilization of this test, especially in non-hospital practice. In this context, working groups of Société Française de Biologie Clinique (SFBC), Association de Langue Française pour l'Etude du Diabète et des Maladies Métaboliques (ALFEDIAM) and Société Française d'Endocrinologie (SFE) have met together, in order to analyze the national status, and to propose practical recommendations for implementing a standardization process on the basis of international experiences. It is recommended to exclusively express results as HbA1c percentage, using methods standardized and certified by comparison to reference methods such as those using Diabetes Control and Complications Trial (DCCT) values. Simultaneously, contacts have been established with manufacturers, and the realisation of periodic quality control surveys was encouraged.

  2. Etude par émission acoustique de la dynamique des dislocations pendant la déformation cyclique de polycristaux d'aluminium

    NASA Astrophysics Data System (ADS)

    Slimani, A.; Fleischmann, P.; Fougères, R.

    1992-06-01

    The cyclic plasticity of 5N polycrystalline aluminium have been studied at room temperature by measuring the continuous acoustic emission (A.E.) due to dislocations movements in the metal. In this study, original data have been obtained in the understanding of continuous A.E. sources. In comparison with classical interpretation given in the literature, the fact that dislocations are arranged according to a dislocation cell structure from the first cycle has been included in the analysis of the results. From this, it has been shown that the amplitude of the A.E. signal is not directly connected with the plastic strain rate prescribed to the fatigue sample and that the probability density function of dislocation loops created during the cycling can be determined. La plasticité cyclique de l'AI 5N polycristallin a été étudiée à la température ambiante à partir de mesures d'émission acoustique continue (E.A.). L'application de la technique de l'E.A. nous a permis d'obtenir des données originales quant aux mécanismes sources d'E.A. Par rapport aux interprétations classiques de la littérature, nous avons fait intervenir le fait que, dès les premiers cycles, une structure cellulaire de dislocations est établie. Nous montrons que l'amplitude du signal d'E.A. n'est plus liée directement à la vitesse de déformation plastique macroscopique. A partir de cette donnée, l'analyse des résultats d'E.A. permet d'obtenir des informations sur la fonction distribution des boucles de dislocations créées au cours de la déformation cyclique.

  3. Zinc in human health: effect of zinc on immune cells.

    PubMed

    Prasad, Ananda S

    2008-01-01

    Although the essentiality of zinc for plants and animals has been known for many decades, the essentiality of zinc for humans was recognized only 40 years ago in the Middle East. The zinc-deficient patients had severe immune dysfunctions, inasmuch as they died of intercurrent infections by the time they were 25 years of age. In our studies in an experimental human model of zinc deficiency, we documented decreased serum testosterone level, oligospermia, severe immune dysfunctions mainly affecting T helper cells, hyperammonemia, neurosensory disorders, and decreased lean body mass. It appears that zinc deficiency is prevalent in the developing world and as many as two billion subjects may be growth retarded due to zinc deficiency. Besides growth retardation and immune dysfunctions, cognitive impairment due to zinc deficiency also has been reported recently. Our studies in the cell culture models showed that the activation of many zinc-dependent enzymes and transcription factors were adversely affected due to zinc deficiency. In HUT-78 (T helper 0 [Th(0)] cell line), we showed that a decrease in gene expression of interleukin-2 (IL-2) and IL-2 receptor alpha(IL-2Ralpha) were due to decreased activation of nuclear factor-kappaB (NF-kappaB) in zinc deficient cells. Decreased NF-kappaB activation in HUT-78 due to zinc deficiency was due to decreased binding of NF-kappaB to DNA, decreased level of NF-kappaB p105 (the precursor of NF-kappaB p50) mRNA, decreased kappaB inhibitory protein (IkappaB) phosphorylation, and decreased Ikappa kappa. These effects of zinc were cell specific. Zinc also is an antioxidant and has anti-inflammatory actions. The therapeutic roles of zinc in acute infantile diarrhea, acrodermatitis enteropathica, prevention of blindness in patients with age-related macular degeneration, and treatment of common cold with zinc have been reported. In HL-60 cells (promyelocytic leukemia cell line), zinc enhances the up-regulation of A20 mRNA, which, via TRAF

  4. Conception, fabrication et validation d'une presse a injection basse pression pour le procede des poudres metalliques =

    NASA Astrophysics Data System (ADS)

    Lamarre, Simon G.

    Le moulage par injection a basse pression de poudre metallique est une technique de mise en forme de pieces de formes complexes. La poudre metallique est melangee avec des polymeres basse viscosite (ex. : cire) pour former un melange homogene a une temperature superieure a la temperature de fusion des polymeres. Pour faciliter l'injection dans la cavite du moule, la composition des melanges est ajustee pour diminuer la viscosite. D'une part, les melanges peu visqueux possedent une bonne moulabilite. D'autre part, le phenomene de la segregation se manifeste rapidement avec les melanges peu visqueux. Les machines commerciales sont munies d'un canal d'injection et d'une valve qui relient le reservoir de melange et la cavite du moule. Le melange reste stationnaire dans ces composantes entre deux sequences d'injection, ce qui le rend propice a la segregation. Plusieurs brevets tentent de resoudre ce probleme en utilisant des pompes et des canaux de recirculation. Ces composantes sont difficiles a nettoyer en raison de leur complexite. Une machine a injection basse pression a ete concue et fabriquee pour l'etude de l'aptitude au moulage des melanges de tres faible viscosite (ex. : 0.1 Pa˙s), qui tient compte du phenomene de segregation et des contraintes de nettoyage. Un piston d'injection puise le volume desire d'un reservoir. Ensuite, un mouvement lateral cisaille le melange a l'intersection entre le reservoir et le cylindre et bouche l'orifice de sortie du reservoir. Le cylindre est degage et peut recevoir le moule. A la suite de l'injection, le piston retourne a la position du reservoir et entre dans son orifice de sortie. Le melange residuel est retourne dans le reservoir, melange et desaere a nouveau. L'appareil a ete valide par des essais d'injectabilite avec un melange de poudre d'acier inoxydable et de liants a basse viscosite. Des essais d'injection ont montre que le melange contenant l'acide stearique a parcouru la plus grande distance dans le moule de forme

  5. Investigation de l'anisotropie du gap supraconducteur dans les composes Ba(Fe(1-x)Co(x))2As2, Ba(1-x)K(x)Fe2As2, LiFeAs et Fe1-deltaTe(1-x)Se(x)

    NASA Astrophysics Data System (ADS)

    Reid, Jean-Philippe

    ommaire La structure du gap supraconducteur et sa modulation sont intimement liees au potentiel d'interaction responsable de l'appariement des electrons d'un supraconducteur. Ainsi, l'etude de la structure du gap-SC et de sa modulation permettent de faire la lumiere sur la nature du mecanisme d'appariement des electrons. A cet egard, les resultats experimentaux des supraconducteurs a base de fer ne cadrent pas dans un seul ensemble, ce qui est en opposition au gap-SC universel des cuprates. Dans ce qui suit, nous presenterons une etude systematique du gap-SC pour plusieurs pnictides. En effet, en utilisant la conductivite thermique, une sonde directionnelle du gap-SC, nous avons ete en mesure de reveler la structure du gap-SC pour les composes suivants : Ba1-xKxFe 2As2, Ba(Fe1-xCo x)2As2, LiFeAs et Fe1-deltaTe 1-xSex. L'etude de ces quatre composes, de trois differentes familles structurales, a pu etablir un tableau partiel mais tres exhaustif de la structure du gap-SC de pnictides. En effet, tel qu'illustre dans cette these, ces quatre composes ne possedent aucun noeud dans leur structure du gap-SC a dopage optimal. Toutefois, a une concentration differente de celle optimale pour les composes K-Ba122 et Co-Ba122, des noeuds apparaissent sur la surface de Fermi, aux extremites 'du dome supraconducteur. Ceci suggere fortement que, pour ces composes, la presence de noeuds sur la surface de Fermi est nuisible a la phase supraconductrice. Mots-cles: Supraconducteurs a base de fer, Pnictides, Structure du gap supraconducteur, Conductivite thermique

  6. The Zinc Transporter Zip5 (Slc39a5) Regulates Intestinal Zinc Excretion and Protects the Pancreas against Zinc Toxicity

    PubMed Central

    Geiser, Jim; De Lisle, Robert C.; Andrews, Glen K.

    2013-01-01

    Background ZIP5 localizes to the baso-lateral membranes of intestinal enterocytes and pancreatic acinar cells and is internalized and degraded coordinately in these cell-types during periods of dietary zinc deficiency. These cell-types are thought to control zinc excretion from the body. The baso-lateral localization and zinc-regulation of ZIP5 in these cells are unique among the 14 members of the Slc39a family and suggest that ZIP5 plays a role in zinc excretion. Methods/Principal Findings We created mice with floxed Zip5 genes and deleted this gene in the entire mouse or specifically in enterocytes or acinar cells and then examined the effects on zinc homeostasis. We found that ZIP5 is not essential for growth and viability but total knockout of ZIP5 led to increased zinc in the liver in mice fed a zinc-adequate (ZnA) diet but impaired accumulation of pancreatic zinc in mice fed a zinc-excess (ZnE) diet. Loss-of-function of enterocyte ZIP5, in contrast, led to increased pancreatic zinc in mice fed a ZnA diet and increased abundance of intestinal Zip4 mRNA. Finally, loss-of-function of acinar cell ZIP5 modestly reduced pancreatic zinc in mice fed a ZnA diet but did not impair zinc uptake as measured by the rapid accumulation of 67zinc. Retention of pancreatic 67zinc was impaired in these mice but the absence of pancreatic ZIP5 sensitized them to zinc-induced pancreatitis and exacerbated the formation of large cytoplasmic vacuoles containing secretory protein in acinar cells. Conclusions These studies demonstrate that ZIP5 participates in the control of zinc excretion in mice. Specifically, they reveal a paramount function of intestinal ZIP5 in zinc excretion but suggest a role for pancreatic ZIP5 in zinc accumulation/retention in acinar cells. ZIP5 functions in acinar cells to protect against zinc-induced acute pancreatitis and attenuate the process of zymophagy. This suggests that it may play a role in autophagy. PMID:24303081

  7. Déprescription des agonistes des récepteurs des benzodiazépines

    PubMed Central

    Pottie, Kevin; Thompson, Wade; Davies, Simon; Grenier, Jean; Sadowski, Cheryl A.; Welch, Vivian; Holbrook, Anne; Boyd, Cynthia; Swenson, Robert; Ma, Andy; Farrell, Barbara

    2018-01-01

    Résumé Objectif Formuler des lignes directrices fondées sur les données probantes visant à aider les cliniciens à décider du moment et de la façon sécuritaire de réduire la dose des agonistes des récepteurs des benzodiazépines (BZRA) pour mettre fin au traitement; se concentrer sur le niveau le plus élevé des données disponibles et obtenir les commentaires des professionnels de première ligne durant le processus de rédaction, de révision et d’adoption des lignes directrices. Méthodes L’équipe comptait 8 cliniciens (1 médecin de famille, 2 psychiatres, 1 psychologue clinique, 1 pharmacologue clinique, 2 pharmaciennes cliniques et 1 gériatre) et une spécialiste de la méthodologie; les membres ont divulgué tout conflit d’intérêts. Nous avons eu recours à un processus systématique, y compris l’approche GRADE (Grading of Recommendations Assessment, Development and Evaluation) pour formuler les lignes directrices. Les données ont été générées par une revue systématique d’études portant sur la déprescription des BZRA contre l’insomnie, de même que par une revue des revues sur les torts liés à la poursuite du traitement par BZRA et des synthèses narratives sur les préférences des patients et les répercussions sur les ressources. Ces données et le score GRADE de qualité des données ont servi à formuler les recommandations. L’équipe a peaufiné le texte sur le contenu et les recommandations des lignes directrices par consensus et a synthétisé les considérations cliniques afin de répondre aux questions des cliniciens de première ligne. Une version préliminaire des lignes directrices a été révisée par les cliniciens et les intervenants. Recommandations Nous recommandons d’offrir la déprescription (réduction lente de la dose) des BZRA à tous les patients âgés (≥ 65 ans) sous un BZRA, sans égard à la durée de l’usage, et suggérons d’offrir la déprescription (réduction lente de la dose)

  8. Zinc pharmacokinetic parameters in the determination of body zinc status in children.

    PubMed

    Vale, S H L; Leite, L D; Alves, C X; Dantas, M M G; Costa, J B S; Marchini, J S; França, M C; Brandão-Neto, J

    2014-02-01

    Serum or tissue zinc concentrations are often used to assess body zinc status. However, all of these methods are relatively inaccurate. Thus, we investigated three different kinetic methods for the determination of zinc clearance to establish which of these could detect small changes in the body zinc status of children. Forty apparently healthy children were studied. Renal handling of zinc was investigated during intravenous zinc administration (0.06537 mg Zn/kg of body weight), both before and after oral zinc supplementation (5 mg Zn/day for 3 months). Three kinetic methods were used to determine zinc clearance: CZn-Formula A and CZn-Formula B were both used to calculate systemic clearance; the first is a general formula and the second is used for the specific analysis of a single-compartment model; CZn-Formula C is widely used in medical practices to analyze kinetic routine. Basal serum zinc values, which were within the reference range for healthy children, increased significantly after oral zinc supplementation. The three formulas used gave different results for zinc clearance both before and after oral zinc supplementation. CZn-Formula B showed a positive correlation with basal serum zinc concentration after oral supplementation (R2=0.1172, P=0.0306). In addition, CZn-Formula B (P=0.0002) was more effective than CZn-Formula A (P=0.6028) and CZn-Formula C (P=0.0732) in detecting small variations in body zinc status. All three of the formulas used are suitable for studying zinc kinetics; however, CZn-Formula B is particularly effective at detecting small changes in body zinc status in healthy children.

  9. Morphology control of zinc regeneration for zinc-air fuel cell and battery

    NASA Astrophysics Data System (ADS)

    Wang, Keliang; Pei, Pucheng; Ma, Ze; Xu, Huachi; Li, Pengcheng; Wang, Xizhong

    2014-12-01

    Morphology control is crucial both for zinc-air batteries and for zinc-air fuel cells during zinc regeneration. Zinc dendrite should be avoided in zinc-air batteries and zinc pellets are yearned to be formed for zinc-air fuel cells. This paper is mainly to analyze the mechanism of shape change and to control the zinc morphology during charge. A numerical three-dimensional model for zinc regeneration is established with COMSOL software on the basis of ionic transport theory and electrode reaction electrochemistry, and some experiments of zinc regeneration are carried out. The deposition process is qualitatively analyzed by the kinetics Monte Carlo method to study the morphological change from the electrocrystallization point of view. Morphological evolution of deposited zinc under different conditions of direct currents and pulse currents is also investigated by simulation. The simulation shows that parametric variables of the flowing electrolyte, the surface roughness and the structure of the electrode, the charging current and mode affect morphological evolution. The uniform morphology of deposited zinc is attained at low current, pulsating current or hydrodynamic electrolyte, and granular morphology is obtained by means of an electrode of discrete columnar structure in combination with high current and flowing electrolyte.

  10. Zinc and Autophagy

    PubMed Central

    Liuzzi, Juan P.; Guo, Liang; Yoo, Changwon; Stewart, Tiffanie S

    2014-01-01

    Autophagy is a highly conserved degradative process through which cells overcome stressful conditions. Inasmuch as faulty autophagy has been associated with aging, neuronal degeneration disorders, diabetes, and fatty liver, autophagy is regarded as a potential therapeutic target. This review summarizes the present state of knowledge concerning the role of zinc in the regulation of autophagy, the role of autophagy in zinc metabolism, and the potential role of autophagy as a mediator of the protective effects of zinc. Data from in vitro studies consistently support the notion that zinc is critical for early and late autophagy. Studies have shown inhibition of early and late autophagy in cells cultured in medium treated with zinc chelators. Conversely, excess zinc added to the medium has shown to potentiate the stimulation of autophagy by tamoxifen, H2O2, ethanol and dopamine. The potential role of autophagy in zinc homeostasis has just begun to be investigated.Increasing evidence indicates that autophagy dysregulation causes significant changes in cellular zinc homeostasis. Autophagy may mediate the protective effect of zinc against lipid accumulation, apoptosis and inflammation by promoting degradation of lipid droplets, inflammasomes, p62/SQSTM1 and damaged mitochondria.Studies with humans and animal models are necessary to determine whether autophagy is influenced by zinc intake. PMID:25012760

  11. A dynamic model for predicting growth in zinc-deficient stunted infants given supplemental zinc.

    PubMed

    Wastney, Meryl E; McDonald, Christine M; King, Janet C

    2018-05-01

    Zinc deficiency limits infant growth and increases susceptibility to infections, which further compromises growth. Zinc supplementation improves the growth of zinc-deficient stunted infants, but the amount, frequency, and duration of zinc supplementation required to restore growth in an individual child is unknown. A dynamic model of zinc metabolism that predicts changes in weight and length of zinc-deficient, stunted infants with dietary zinc would be useful to define effective zinc supplementation regimens. The aims of this study were to develop a dynamic model for zinc metabolism in stunted, zinc-deficient infants and to use that model to predict the growth response when those infants are given zinc supplements. A model of zinc metabolism was developed using data on zinc kinetics, tissue zinc, and growth requirements for healthy 9-mo-old infants. The kinetic model was converted to a dynamic model by replacing the rate constants for zinc absorption and excretion with functions for these processes that change with zinc intake. Predictions of the dynamic model, parameterized for zinc-deficient, stunted infants, were compared with the results of 5 published zinc intervention trials. The model was then used to predict the results for zinc supplementation regimes that varied in the amount, frequency, and duration of zinc dosing. Model predictions agreed with published changes in plasma zinc after zinc supplementation. Predictions of weight and length agreed with 2 studies, but overpredicted values from a third study in which other nutrient deficiencies may have been growth limiting; the model predicted that zinc absorption was impaired in that study. The model suggests that frequent, smaller doses (5-10 mg Zn/d) are more effective for increasing growth in stunted, zinc-deficient 9-mo-old infants than are larger, less-frequent doses. The dose amount affects the duration of dosing necessary to restore and maintain plasma zinc concentration and growth.

  12. Production of zinc pellets

    DOEpatents

    Cooper, J.F.

    1996-11-26

    Uniform zinc pellets are formed for use in batteries having a stationary or moving slurry zinc particle electrode. The process involves the cathodic deposition of zinc in a finely divided morphology from battery reaction product onto a non-adhering electrode substrate. The mossy zinc is removed from the electrode substrate by the action of gravity, entrainment in a flowing electrolyte, or by mechanical action. The finely divided zinc particles are collected and pressed into pellets by a mechanical device such as an extruder, a roller and chopper, or a punch and die. The pure zinc pellets are returned to the zinc battery in a pumped slurry and have uniform size, density and reactivity. Applications include zinc-air fuel batteries, zinc-ferricyanide storage batteries, and zinc-nickel-oxide secondary batteries. 6 figs.

  13. Production of zinc pellets

    DOEpatents

    Cooper, John F.

    1996-01-01

    Uniform zinc pellets are formed for use in batteries having a stationary or moving slurry zinc particle electrode. The process involves the cathodic deposition of zinc in a finely divided morphology from battery reaction product onto a non-adhering electrode substrate. The mossy zinc is removed from the electrode substrate by the action of gravity, entrainment in a flowing electrolyte, or by mechanical action. The finely divided zinc particles are collected and pressed into pellets by a mechanical device such as an extruder, a roller and chopper, or a punch and die. The pure zinc pellets are returned to the zinc battery in a pumped slurry and have uniform size, density and reactivity. Applications include zinc-air fuel batteries, zinc-ferricyanide storage batteries, and zinc-nickel-oxide secondary batteries.

  14. La matério-vigilance dans un Centre Hospitalo-Universitaire du Centre-Est tunisien: enquête auprès des médecins

    PubMed Central

    Mahjoub, Mohamed; Jedidi, Maher; Masmoudi, Tasnim; Bouafia, Nabiha; Njah, Mansour

    2016-01-01

    Introduction Pour la meilleure gestion des risques en milieu hospitalier et l’amélioration de la qualité et la sécurité de nos soins, le CHU de Sousse (Tunisie), a mis en place, suite aux recommandations de l’ANCSEP (Agence Nationale de Contrôle Sanitaire et Environnementale des Produits) un système de matério-vigilance (MV). En Tunisie l’absence d’un cadre réglementaire organisant la MV est l’obstacle majeur à l’implication des soignants à ce système. L’objectif de cette étude est de déterminer les connaissances, attitudes et pratiques des médecins du CHU quant à la mise en place du système de MV. Méthodes Etude descriptive de type CAP (connaissances, attitudes et pratiques) transversale auprès de tous les médecins titulaires exerçant au CHU de Sousse (Tunisie) qui sont utilisateurs des dispositifs médicaux (DMs) lors de leur pratique d’activité de soin. Un questionnaire auto-administré, préétabli et pré-testé a été établi. Saisie et l’analysée des données par logiciel SPSS20.0. Résultats Le taux de réponse de 51,9 % (183/95), un manque des connaissances relatif à la MV a été rapporté. Plus de la moitié des répondants ne connaissent pas le correspondant local de son établissement et l’existence d’un formulaire standardisé de signalement. Concernant les attitudes, 89,5 % notifient l’intérêt de mise en place du système de MV et 37,5 % reconnaissent que le signalement doit émaner du soignant constatant l’incident. Pour les pratiques, la majorité confirment l’absence d’une gestion organisée de la maintenance des DMs dans leurs services. 90,5 % expriment leurs souhaits de recevoir une information mais peu d’entre eux expriment leurs désirs de suivre une formation (57,9 %). Conclusion Un manque d’information et de formation dans un domaine pourtant sensible et devant être lourdement réglementé est soulevé. La promulgation de textes réglementaires est nécessaire afin de promouvoir le

  15. Suivi prospectif sur 5 ans des tentatives de suicide en population clinique dans la région de Fès, Maroc

    PubMed Central

    Aarab, Chadya; Elghazouani, Fatima; Aalouane, Rachid; Rammouz, Ismail

    2014-01-01

    Au Maroc, les tentatives de suicide (TS) demeurent un sujet mal évalué à cause de considérations socioculturelles et l'absence d'approche longitudinale. L'objectif principal était d’évaluer le devenir des suicidants après 5ans au centre universitaire psychiatrique de Fès, les objectifs secondaires étaient l'estimation de la prévalence des TS, préciser les étiologies les plus fréquentes, et établir une corrélation entre les paramètres sociodémographiques, cliniques et évolutifs. Etude prospective à visée transversale et longitudinale, incluant les suicidants vus à l'hôpital psychiatrique de Fès, avec un suivi longitudinal sur 5ans. L’évaluation a été faite par un hétéro-questionnaire et le Mini International Neuropsychiatric Interview (MINI) cherchant le trouble psychiatrique sous jacent. On a recruté 105 patients suicidants, 62% des femmes, l’âge moyen est de 29,23ans. La prévalence des tentatives de suicide est de 3% sur l'ensemble des consultants à l’établissement. Les troubles de l'humeur, psychotiques et de personnalité ont occupé respectivement 37,6%, 27,7%, et 25,7% des cas. La récidive suicidaire a été notée chez 54% des patients, était significativement corrélée à la vie solitaire (P: 0,039) et à la présence d'antécédents familiaux de TS (P: 0,046). L'utilisation de moyens violents était significativement fréquente chez les patients psychotiques. Après 5ans, 32 patients ont répondu à notre appel. Le taux de récidive était de 15%. On a noté trois cas de décès dont deux suicides confirmés. Les résultats confirment les données de la littérature scientifique avec certaines particularités cliniques et évolutives. PMID:25478042

  16. Zinc Signals and Immunity.

    PubMed

    Maywald, Martina; Wessels, Inga; Rink, Lothar

    2017-10-24

    Zinc homeostasis is crucial for an adequate function of the immune system. Zinc deficiency as well as zinc excess result in severe disturbances in immune cell numbers and activities, which can result in increased susceptibility to infections and development of especially inflammatory diseases. This review focuses on the role of zinc in regulating intracellular signaling pathways in innate as well as adaptive immune cells. Main underlying molecular mechanisms and targets affected by altered zinc homeostasis, including kinases, caspases, phosphatases, and phosphodiesterases, will be highlighted in this article. In addition, the interplay of zinc homeostasis and the redox metabolism in affecting intracellular signaling will be emphasized. Key signaling pathways will be described in detail for the different cell types of the immune system. In this, effects of fast zinc flux, taking place within a few seconds to minutes will be distinguish from slower types of zinc signals, also designated as "zinc waves", and late homeostatic zinc signals regarding prolonged changes in intracellular zinc.

  17. Zinc Signals and Immunity

    PubMed Central

    Maywald, Martina; Wessels, Inga; Rink, Lothar

    2017-01-01

    Zinc homeostasis is crucial for an adequate function of the immune system. Zinc deficiency as well as zinc excess result in severe disturbances in immune cell numbers and activities, which can result in increased susceptibility to infections and development of especially inflammatory diseases. This review focuses on the role of zinc in regulating intracellular signaling pathways in innate as well as adaptive immune cells. Main underlying molecular mechanisms and targets affected by altered zinc homeostasis, including kinases, caspases, phosphatases, and phosphodiesterases, will be highlighted in this article. In addition, the interplay of zinc homeostasis and the redox metabolism in affecting intracellular signaling will be emphasized. Key signaling pathways will be described in detail for the different cell types of the immune system. In this, effects of fast zinc flux, taking place within a few seconds to minutes will be distinguish from slower types of zinc signals, also designated as “zinc waves”, and late homeostatic zinc signals regarding prolonged changes in intracellular zinc. PMID:29064429

  18. Zinc in Cellular Regulation: The Nature and Significance of "Zinc Signals".

    PubMed

    Maret, Wolfgang

    2017-10-31

    In the last decade, we witnessed discoveries that established Zn 2+ as a second major signalling metal ion in the transmission of information within cells and in communication between cells. Together with Ca 2+ and Mg 2+ , Zn 2+ covers biological regulation with redox-inert metal ions over many orders of magnitude in concentrations. The regulatory functions of zinc ions, together with their functions as a cofactor in about three thousand zinc metalloproteins, impact virtually all aspects of cell biology. This article attempts to define the regulatory functions of zinc ions, and focuses on the nature of zinc signals and zinc signalling in pathways where zinc ions are either extracellular stimuli or intracellular messengers. These pathways interact with Ca 2+ , redox, and phosphorylation signalling. The regulatory functions of zinc require a complex system of precise homeostatic control for transients, subcellular distribution and traffic, organellar homeostasis, and vesicular storage and exocytosis of zinc ions.

  19. Zinc and Wound Healing: A Review of Zinc Physiology and Clinical Applications.

    PubMed

    Kogan, Samuel; Sood, Aditya; Garnick, Mark S

    2017-04-01

    Our understanding of the role of zinc in normal human physiology is constantly expanding, yet there are major gaps in our knowledge with regard to the function of zinc in wound healing. This review aims to provide the clinician with sufficient understanding of zinc biology and an up-to-date perspective on the role of zinc in wound healing. Zinc is an essential ion that is crucial for maintenance of normal physiology, and zinc deficiency has many manifestations ranging from delayed wound healing to immune dysfunction and impairment of multiple sensory systems. While consensus has been reached regarding the detrimental effects of zinc deficiency on wound healing, there is considerable discord in the literature on the optimal methods and true benefits of zinc supplementation.

  20. Zinc

    MedlinePlus

    ... Guidelines for Americans and the U.S. Department of Agriculture's MyPlate . Where can I find out more about ... on food sources of zinc: U.S. Department of Agriculture's (USDA’s) National Nutrient Database Nutrient List for zinc ( ...

  1. Hyperaccumulation of zinc by zinc-depleted Candida utilis grown in chemostat culture.

    PubMed

    Lawford, H G; Pik, J R; Lawford, G R; Williams, T; Kligerman, A

    1980-01-01

    The steady-state levels of zinc in Candida utilis yeast grown in continuous culture under conditions of zinc limitations are <1nmol Zn2+/mg dry weight of cells. Unlike carbon-limited cells, zinc-depleted cells from a zinc-limited chemostat possess the capacity to accumulate and store zinc at levels far in excess of the steady-state level of 4 nmol/mg dry biomass observed in carbon-limited chemostat cultures. Zinc uptake is energy-dependent and apparently undirectional since accumulated 65Zn neither exists from preloaded cells nor exchanges with cold Zn2+. The transport system exhibits a high affinity for Zn2+ (Km =.36micrM) with a Vmaxof 2.2 nmol per minute per milligram dry weight of cells. Growth during the period of the uptake assay is responsible for the apparent plateau level of 35 nmol Zn2+/mg dry weight of cells achieved after 20-30 min in the presence of 65Zn at pH 4.5 and 30 degrees C. Inhibition of growth during the uptake assay by cycloheximide results in a biphasic linear pattern of zinc accumulation where the cellular zinc is about 60 nmol/mg dry weight after 1 h. The enhanced level of accumulated zinc is not inhibtory to growth. Zinc-depleted C. utilis contains elevated amounts of polyphosphate and this anionic evidence does not allow discrimination between possible regulation of zinc homestasis either by inhibitions of zinc efflux through control of the membrane carrier or by control of the synthesis of a cytoplasmic zinc-sequestering macromolecule.

  2. Update on zinc biology.

    PubMed

    Solomons, Noel W

    2013-01-01

    Zinc has become a prominent nutrient of clinical and public health interest in the new millennium. Functions and actions for zinc emerge as increasingly ubiquitous in mammalian anatomy, physiology and metabolism. There is undoubtedly an underpinning in fundamental biology for all of the aspects of zinc in human health (clinical and epidemiological) in pediatric and public health practice. Unfortunately, basic science research may not have achieved a full understanding as yet. As a complement to the applied themes in the companion articles, a selection of recent advances in the domains homeostatic regulation and transport of zinc is presented; they are integrated, in turn, with findings on genetic expression, intracellular signaling, immunity and host defense, and bone growth. The elements include ionic zinc, zinc transporters, metallothioneins, zinc metalloenzymes and zinc finger proteins. In emerging basic research, we find some plausible mechanistic explanations for delayed linear growth with zinc deficiency and increased infectious disease resistance with zinc supplementation. Copyright © 2013 S. Karger AG, Basel.

  3. Zinc at glutamatergic synapses.

    PubMed

    Paoletti, P; Vergnano, A M; Barbour, B; Casado, M

    2009-01-12

    It has long been known that the mammalian forebrain contains a subset of glutamatergic neurons that sequester zinc in their synaptic vesicles. This zinc may be released into the synaptic cleft upon neuronal activity. Extracellular zinc has the potential to interact with and modulate many different synaptic targets, including glutamate receptors and transporters. Among these targets, NMDA receptors appear particularly interesting because certain NMDA receptor subtypes (those containing the NR2A subunit) contain allosteric sites exquisitely sensitive to extracellular zinc. The existence of these high-affinity zinc binding sites raises the possibility that zinc may act both in a phasic and tonic mode. Changes in zinc concentration and subcellular zinc distribution have also been described in several pathological conditions linked to glutamatergic transmission dysfunctions. However, despite intense investigation, the functional significance of vesicular zinc remains largely a mystery. In this review, we present the anatomy and the physiology of the glutamatergic zinc-containing synapse. Particular emphasis is put on the molecular and cellular mechanisms underlying the putative roles of zinc as a messenger involved in excitatory synaptic transmission and plasticity. We also highlight the many controversial issues and unanswered questions. Finally, we present and compare two widely used zinc chelators, CaEDTA and tricine, and show why tricine should be preferred to CaEDTA when studying fast transient zinc elevations as may occur during synaptic activity.

  4. Zinc and Zinc Transporters: Novel Regulators of Ventricular Myocardial Development.

    PubMed

    Lin, Wen; Li, Deqiang

    2018-06-01

    Ventricular myocardial development is a well-orchestrated process involving different cardiac structures, multiple signal pathways, and myriad proteins. Dysregulation of this important developmental event can result in cardiomyopathies, such as left ventricle non-compaction, which affect the pediatric population and the adults. Human and mouse studies have shed light upon the etiology of some cardiomyopathy cases and highlighted the contribution of both genetic and environmental factors. However, the regulation of ventricular myocardial development remains incompletely understood. Zinc is an essential trace metal with structural, enzymatic, and signaling function. Perturbation of zinc homeostasis has resulted in developmental and physiological defects including cardiomyopathy. In this review, we summarize several mechanisms by which zinc and zinc transporters can impact the regulation of ventricular myocardial development. Based on our review, we propose that zinc deficiency and mutations of zinc transporters may underlie some cardiomyopathy cases especially those involving ventricular myocardial development defects.

  5. European Organization for Research and Treatment of Cancer and Groupe d'Etude des Lymphomes de l'Adulte very favorable and favorable, lymphocyte-predominant Hodgkin disease.

    PubMed

    Wilder, Richard B; Schlembach, Pamela J; Jones, Dan; Chronowski, Gregory M; Ha, Chul S; Younes, Anas; Hagemeister, Fredrick B; Barista, Ibrahim; Cabanillas, Fernando; Cox, James D

    2002-03-15

    Lymphocyte-predominant Hodgkin disease (LPHD) is rare and has a natural history different from that of classic Hodgkin disease. There is little information in the literature regarding the role of chemotherapy in patients with early-stage LPHD. The objective of this study was to examine recurrence free survival (RFS), overall survival (OS), and patterns of first recurrence in patients with LPHD who were treated with radiotherapy alone or with chemotherapy followed by radiotherapy. From 1963 to 1996, 48 consecutive patients ages 16-49 years (median, 28 years) with Ann Arbor Stage I (n = 30 patients) or Stage II (n = 18 patients), very favorable (VF; n = 5 patients) or favorable (F; n = 43 patients) LPHD, according to the European Organization for Research and Treatment of Cancer and Groupe d'Etude des Lymphomes de l'Adulte (EORTC-GELA) criteria, received radiotherapy alone (n = 37 patients) or received chemotherapy followed by radiotherapy (n = 11 patients). The percentages of patients with VF disease (11% vs. 9% in the radiotherapy group vs. the chemotherapy plus radiotherapy group, respectively) or F disease (89% vs. 91%, respectively) within the two treatment groups were similar (P = 1.00). A median of three cycles of chemotherapy with mechlorethamine, vincristine, procarbazine, and prednisone (MOPP) or with mitoxantrone, vincristine, vinblastine, and prednisone (NOVP) was given initially to six patients and five patients, respectively. A median total radiotherapy dose of 40 grays (Gy) given in daily fractions of 2.0 Gy was delivered to both treatment groups. The median follow-up was 9.3 years, and 98% of patients were observed for > or = 3.0 years. RFS was similar for patients who were treated with radiotherapy alone and patients who were treated with chemotherapy followed by radiotherapy (10-year survival rates: 77% and 68%, respectively; P = 0.89). The OS rate also was similar for the two groups (10-year survival rates: 90% and 100%, respectively; P = 0

  6. Vecteurs Singuliers des Theories des Champs Conformes Minimales

    NASA Astrophysics Data System (ADS)

    Benoit, Louis

    En 1984 Belavin, Polyakov et Zamolodchikov revolutionnent la theorie des champs en explicitant une nouvelle gamme de theories, les theories quantiques des champs bidimensionnelles invariantes sous les transformations conformes. L'algebre des transformations conformes de l'espace-temps presente une caracteristique remarquable: en deux dimensions elle possede un nombre infini de generateurs. Cette propriete impose de telles conditions aux fonctions de correlations qu'il est possible de les evaluer sans aucune approximation. Les champs des theories conformes appartiennent a des representations de plus haut poids de l'algebre de Virasoro, une extension centrale de l'algebre conforme du plan. Ces representations sont etiquetees par h, le poids conforme de leur vecteur de plus haut poids, et par la charge centrale c, le facteur de l'extension centrale, commune a toutes les representations d'une meme theorie. Les theories conformes minimales sont constituees d'un nombre fini de representations. Parmi celles-ci se trouvent des theories unitaires dont les representation forment la serie discrete de l'algebre de Virasoro; leur poids h a la forme h_{p,q}(m)=[ (p(m+1) -qm)^2-1] (4m(m+1)), ou p,q et m sont des entiers positifs et p+q<= m+1. L'entier m parametrise la charge centrale: c(m)=1 -{6over m(m+1)} avec n>= 2. Ces representations possedent un sous-espace invariant engendre par deux sous-representations avec h_1=h_{p,q} + pq et h_2=h_{p,q} + (m-p)(m+1-q) dont chacun des vecteurs de plus haut poids portent le nom de vecteur singulier et sont notes respectivement |Psi _{p,q}> et |Psi_{m-p,m+1-q}>. . Les theories super-conformes sont une version super-symetrique des theories conformes. Leurs champs appartiennent a des representation de plus haut poids de l'algebre de Neveu-Schwarz, une des deux extensions super -symetriques de l'algebre de Virasoro. Les theories super -conformes minimales possedent la meme structure que les theories conformes minimales. Les representations

  7. Zinc Biochemistry: From a Single Zinc Enzyme to a Key Element of Life12

    PubMed Central

    Maret, Wolfgang

    2013-01-01

    The nutritional essentiality of zinc for the growth of living organisms had been recognized long before zinc biochemistry began with the discovery of zinc in carbonic anhydrase in 1939. Painstaking analytical work then demonstrated the presence of zinc as a catalytic and structural cofactor in a few hundred enzymes. In the 1980s, the field again gained momentum with the new principle of “zinc finger” proteins, in which zinc has structural functions in domains that interact with other biomolecules. Advances in structural biology and a rapid increase in the availability of gene/protein databases now made it possible to predict zinc-binding sites from metal-binding motifs detected in sequences. This procedure resulted in the definition of zinc proteomes and the remarkable estimate that the human genome encodes ∼3000 zinc proteins. More recent developments focus on the regulatory functions of zinc(II) ions in intra- and intercellular information transfer and have tantalizing implications for yet additional functions of zinc in signal transduction and cellular control. At least three dozen proteins homeostatically control the vesicular storage and subcellular distribution of zinc and the concentrations of zinc(II) ions. Novel principles emerge from quantitative investigations on how strongly zinc interacts with proteins and how it is buffered to control the remarkably low cellular and subcellular concentrations of free zinc(II) ions. It is fair to conclude that the impact of zinc for health and disease will be at least as far-reaching as that of iron. PMID:23319127

  8. The COROT telescope

    NASA Astrophysics Data System (ADS)

    Viard, Thierry

    2017-11-01

    The COROT telescope, of which the customer is the French "INSU" / "CNES" (Institut National des Sciences de l'Univers / Centre National des Etudes Spatiales) is in fact a very precise and stable imaging instrument, which will be pointed towards fixed areas in the sky (each containing more than 3000 target stars) for periods of at least 5 months, in order to carry out its two missions.

  9. Tracing of Zinc Nanocrystals in the Anterior Pituitary of Zinc-Deficient Wistar Rats.

    PubMed

    Kuldeep, Anjana; Nair, Neena; Bedwal, Ranveer Singh

    2017-06-01

    The aim of this study was to trace zinc nanocrystals in the anterior pituitary of zinc-deficient Wistar rats by using autometallographic technique. Male Wistar rats (30-40 days of age, pre-pubertal period) of 40-50 g body weight were divided into the following: the ZC (zinc control) group-fed with 100 ppm zinc in diet, the ZD (zinc-deficient) group-fed with zinc-deficient (1.00 ppm) diet and the PF (pair-fed) group-received 100 ppm zinc in diet. The experiments were set for 2 and 4 weeks. Pituitary was removed and processed for the autometallographic technique. The control and pair-fed groups retained their normal morphological features. However, male Wistar rats fed on zinc-deficient diet for 2 and 4 weeks displayed a wide range of symptoms such as significant (P < 0.05) decrease in diet consumption, body weight and pituitary weight and decrease in gradation of intensity of zinc nanocrystals in the nuclei. The present findings suggest that the dietary zinc deficiency causes decreased intensity of zinc nanocrystals localization and their distribution in the pituitary thereby contributing to the dysfunction of the pituitary of the male Wistar rats. The severity of zinc deficiency symptoms progressed after the second week of the experiment. Decreased intensity of zinc nanocrystals attenuates the pituitary function which would exert its affect on other endocrine organs impairing their functions indicating that the metabolic regulation of pituitary is mediated to a certain extent by zinc and/or hypothalamus-hypophysial system which also reflects its essentiality during the period of growth.

  10. 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

  11. Etude de la prévalence des infections nosocomiales et des facteurs associes dans les deux hopitaux universitaires de Lubumbashi, République Démocratique du Congo: cas des Cliniques Universitaires de Lubumbashi et l’Hôpital Janson Sendwe

    PubMed Central

    Kakupa, Danny Kasongo; Muenze, Prosper Kalenga; Byl, Baudouin; Wilmet, Michèle Dramaix

    2016-01-01

    Introduction Estimer la prévalence « un jour donné » des infections nosocomiales et déterminer leurs facteurs associés, ensuite estimer la prévalence des micro-organismes responsables des infections nosocomiales de Lubumbashi, République Démocratique du Congo. Méthodes Une étude transversale descriptive a été menée dans les deux hôpitaux de Lubumbashi au sein de cinq services d’hospitalisation (Chirurgie, Gynéco-Obstétrique, Médecine interne, Pédiatrie et Réanimation). L’échantillon était constitué de 171 patients hospitalisés et qui ont été interrogés à l’aide d’un questionnaire standardisé. La fiche médicale nous a permit de connaitre le type d’antibiotique administré au patient 48 heures après d’admission. Notre étude s’est déroulée durant le mois de février 2010 dans le cadre de la première enquête locale de prévalence des infections nosocomiales. Résultats Notre étude a permis de recenser 59 patients atteints d’une infection nosocomiale. La prévalence globale est de 34,5% (dont 17,0% pour une infection nosocomiale acquise et 17,5% pour une infection importée). L’infection nosocomiale a été définie selon l’Organisation Mondiale de la Santé comme toute infection acquise pendant un séjour à l’hôpital et qui n’était ni présente ni en incubation au moment de l’admission du patient. Les facteurs de risque suivants ont été associés aux infections nosocomiales acquises: durée d’hospitalisation (les patients admis en long séjour, séjour de plus de sept jours d’hospitalisation avaient un risque plus élevé que ceux admis en séjour court, séjour inférieur ou égal à sept jours d’hospitalisation (Ratio de prévalence: RP =3,6 [IC a 95% 1,4-8,9]). Parmi les infections nosocomiales, les infections du site opératoire étaient les plus fréquentes (27,1%), suivies des infections pulmonaires (22,0%) et des infections urinaires (17,0%). L’examen microbiologique a permis de mettre

  12. Contribution of Zinc Solubilizing Bacteria in Growth Promotion and Zinc Content of Wheat.

    PubMed

    Kamran, Sana; Shahid, Izzah; Baig, Deeba N; Rizwan, Muhammad; Malik, Kauser A; Mehnaz, Samina

    2017-01-01

    Zinc is an imperative micronutrient required for optimum plant growth. Zinc solubilizing bacteria are potential alternatives for zinc supplementation and convert applied inorganic zinc to available forms. This study was conducted to screen zinc solubilizing rhizobacteria isolated from wheat and sugarcane, and to analyze their effect on wheat growth and development. Fourteen exo-polysaccharides producing bacterial isolates of wheat were identified and characterized biochemically as well as on the basis of 16S rRNA gene sequences. Along these, 10 identified sugarcane isolates were also screened for zinc solubilizing ability on five different insoluble zinc sources. Out of 24, five strains, i.e., EPS 1 ( Pseudomonas fragi) , EPS 6 ( Pantoea dispersa) , EPS 13 ( Pantoea agglomerans) , PBS 2 ( E. cloacae) and LHRW1 ( Rhizobium sp.) were selected (based on their zinc solubilizing and PGP activities) for pot scale plant experiments. ZnCO 3 was used as zinc source and wheat seedlings were inoculated with these five strains, individually, to assess their effect on plant growth and development. The effect on plants was analyzed based on growth parameters and quantifying zinc content of shoot, root and grains using atomic absorption spectroscopy. Plant experiment was performed in two sets. For first set of plant experiments (harvested after 1 month), maximum shoot and root dry weights and shoot lengths were noted for the plants inoculated with Rhizobium sp. (LHRW1) while E. cloacae (PBS 2) increased both shoot and root lengths. Highest zinc content was found in shoots of E. cloacae (PBS 2) and in roots of P. agglomerans (EPS 13) followed by zinc supplemented control. For second set of plant experiment, when plants were harvested after three months, Pantoea dispersa (EPS 6), P. agglomerans (EPS 13) and E. cloacae (PBS 2) significantly increased shoot dry weights. However, significant increase in root dry weights and maximum zinc content was recorded for Pseudomonas fragi (EPS

  13. Séroprévalence des marqueurs viraux sur les dons du sang au Centre de Transfusion Sanguine, Hôpital Militaire d’Instruction Mohammed V de Rabat

    PubMed Central

    Uwingabiye, Jean; Zahid, Hafidi; Unyendje, Loubet; Hadef, Rachid

    2016-01-01

    Le but de ce travail était de déterminer la prévalence du virus de l’immunodéficience humaine (VIH), du virus de l’hépatite B (VHB) et C (VHC) sur les dons du sang collectés au Centre de transfusion sanguine(CTS) de l’hôpital militaire d’instruction Mohammed V entre 2010 et 2012. Etude rétrospective menée auprès des donneurs de sang militaires âgés de 18 à 50 ans avec prédominance masculine (95%). L’entretien médical pré-don constitue la première barrière de sélection des sujets à risque. Le dépistage biologique était réalisé par technique immuno-enzymatique en milieu liquide utilisant des anticorps et/ou des antigènes. L’ELISA (enzyme linked immuno-sorbent assay) combiné de quatrième génération pour VHC et VIH a été utilisé. La confirmation a été faite en réalisant la même technique en double au CTS et au laboratoire de virologie. Dans notre série de 25661 échantillons testés, la prévalence du VHB était 3,97‰ (n=102), celle de VHC était 2,45 ‰ (n=63), celle de VIH était 0,15 ‰ (n=4). Un seul cas de coïnfection (0,039 ‰) par le VHB et VHC a été noté, aucune association entre VIH-VHB, VIH-VHC ou VHB, VHC et VIH n’a été enregistrée. Les taux faibles de séroprévalence des marqueurs viraux de notre étude montrent l’amélioration des mesures préventives en ce qui concerne la sélection des donneurs et des tests de dépistage. Cette prévalence constatée incite à maintenir l’utilisation du réactif combiné qui est la seule alternative à la biologie moléculaire pour les pays en voie de développement. PMID:28292147

  14. Zinc

    USDA-ARS?s Scientific Manuscript database

    Zinc was recognized as an essential trace metal for humans during the studies of Iranian adolescent dwarfs in the early 1960s. Zinc metal existing as Zn2+ is a strong electron acceptor in biological systems without risks of oxidant damage to cells. Zn2+ functions in the structure of proteins and is ...

  15. Zinc and Chlamydia trachomatis

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Sugarman, B.; Epps, L.R.

    1985-07-01

    Zinc was noted to have significant effects upon the infection of McCoy cells by each of two strains of Chlamydia trachomatis. With a high or low Chlamydia inoculant, the number of infected cells increased up to 200% utilizing supplemental zinc (up to 1 x 10/sup -4/ M) in the inoculation media compared with standard Chlamydia cultivation media (8 x 10/sup -6/ M zinc). Ferric chloride and calcium chloride did not effect any such changes. Higher concentrations of zinc, after 2 hr of incubation with Chlamydia, significantly decreased the number of inclusions. This direct effect of zinc on the Chlamydia remainedmore » constant after further repassage of the Chlamydia without supplemental zinc, suggesting a lethal effect of the zinc. Supplemental zinc (up to 10/sup -4/ M) may prove to be a useful addition to inoculation media to increase the yield of culturing for Chlamydia trachomatis. Similarly, topical or oral zinc preparations used by people may alter their susceptibility to Chamydia trachomatis infections.« less

  16. Association between Maternal Zinc Status, Dietary Zinc Intake and Pregnancy Complications: A Systematic Review

    PubMed Central

    Wilson, Rebecca L.; Grieger, Jessica A.; Bianco-Miotto, Tina; Roberts, Claire T.

    2016-01-01

    Adequate zinc stores in the body are extremely important during periods of accelerated growth. However, zinc deficiency is common in developing countries and low maternal circulating zinc concentrations have previously been associated with pregnancy complications. We reviewed current literature assessing circulating zinc and dietary zinc intake during pregnancy and the associations with preeclampsia (PE); spontaneous preterm birth (sPTB); low birthweight (LBW); and gestational diabetes (GDM). Searches of MEDLINE; CINAHL and Scopus databases identified 639 articles and 64 studies were reviewed. In 10 out of 16 studies a difference was reported with respect to circulating zinc between women who gave birth to a LBW infant (≤2500 g) and those who gave birth to an infant of adequate weight (>2500 g), particularly in populations where inadequate zinc intake is prevalent. In 16 of our 33 studies an association was found between hypertensive disorders of pregnancy and circulating zinc; particularly in women with severe PE (blood pressure ≥160/110 mmHg). No association between maternal zinc status and sPTB or GDM was seen; however; direct comparisons between the studies was difficult. Furthermore; only a small number of studies were based on women from populations where there is a high risk of zinc deficiency. Therefore; the link between maternal zinc status and pregnancy success in these populations cannot be established. Future studies should focus on those vulnerable to zinc deficiency and include dietary zinc intake as a measure of zinc status. PMID:27754451

  17. Aspects cliniques et thérapeutiques des anomalies de la jonction pyélo-urétérale au CHU du point G

    PubMed Central

    Tembely, Aly; Kassogué, Amadou; Berthé, Honoré; Ouattara, Zanafon

    2016-01-01

    Cette étude a été faite pour analyser les aspects cliniques et thérapeutiques des anomalies de la jonction pyélo-urétérale. Etude transversale et descriptive portant sur 35 cas d'anomalies de la jonction pyélo-urétérale (AJPU) colligés au service d'Urologie du CHU du Point G durant une période de 4 ans (Janvier 2010 au Décembre 2014). Les données ont été recueillies sur les fiches d'enquête, les dossiers médicaux et les registres du bloc. Les données sociodémographique, clinique et thérapeutique ont été saisies sur Microsoft Word 2007 et analysées sur Excel 2007 et SPSS 18.0. 35 cas d'AJPU ont été colligés en 4 ans. La moyenne d’âge était de 29,3 ans. La douleur lombaire était le motif de consultation le plus fréquent soit 40%. 20% des patients ont été en consultation pour la première fois 10 ans d’évolution symptomatique. Une destruction rénale avait été observée dans 28,6%. Le couple Echographie + UIV a permis d’établir le diagnostic chez 37,1%. La complication lithiasique était présente chez 17,1% des patients. 51,4% des patients ont reçu une pyéloplastie à ciel ouvert selon Anderson KUSS. L'anomalie de la jonction pyélo-urétérale dans notre étude a été caractérisée par un retard de consultation avec des complications redoutables. La chirurgie à ciel ouvert a été le gold standard avec des résultats satisfaisants. L'endopyéloplastie, la cure de la jonction coelioscopique sont des chirurgies mini invasives non disponible chez nous mais à encourager et à intégrer dans l'arsenal thérapeutique. PMID:27516821

  18. Transformation of zinc hydroxide chloride monohydrate to crystalline zinc oxide.

    PubMed

    Moezzi, Amir; Cortie, Michael; McDonagh, Andrew

    2016-04-25

    Thermal decomposition of layered zinc hydroxide double salts provides an interesting alternative synthesis for particles of zinc oxide. Here, we examine the sequence of changes occurring as zinc hydroxide chloride monohydrate (Zn5(OH)8Cl2·H2O) is converted to crystalline ZnO by thermal decomposition. The specific surface area of the resultant ZnO measured by BET was 1.3 m(2) g(-1). A complicating and important factor in this process is that the thermal decomposition of zinc hydroxide chloride is also accompanied by the formation of volatile zinc-containing species under certain conditions. We show that this volatile compound is anhydrous ZnCl2 and its formation is moisture dependent. Therefore, control of atmospheric moisture is an important consideration that affects the overall efficiency of ZnO production by this process.

  19. Functional studies of Drosophila zinc transporters reveal the mechanism for dietary zinc absorption and regulation

    PubMed Central

    2013-01-01

    Background Zinc is key to the function of many proteins, but the process of dietary zinc absorption is not well clarified. Current knowledge about dietary zinc absorption is fragmented, and mostly derives from incomplete mammalian studies. To gain a comprehensive picture of this process, we systematically characterized all zinc transporters (that is, the Zip and ZnT family members) for their possible roles in dietary zinc absorption in a genetically amenable model organism, Drosophila melanogaster. Results A set of plasma membrane-resident zinc transporters was identified to be responsible for absorbing zinc from the lumen into the enterocyte and the subsequent exit of zinc to the circulation. dZip1 and dZip2, two functionally overlapping zinc importers, are responsible for absorbing zinc from the lumen into the enterocyte. Exit of zinc to the circulation is mediated through another two functionally overlapping zinc exporters, dZnT1, and its homolog CG5130 (dZnT77C). Somewhat surprisingly, it appears that the array of intracellular ZnT proteins, including the Golgi-resident dZnT7, is not directly involved in dietary zinc absorption. By modulating zinc status in different parts of the body, we found that regulation of dietary zinc absorption, in contrast to that of iron, is unresponsive to bodily needs or zinc status outside the gut. The zinc transporters that are involved in dietary zinc absorption, including the importers dZip1 and dZip2, and the exporter dZnT1, are respectively regulated at the RNA and protein levels by zinc in the enterocyte. Conclusions Our study using the model organism Drosophila thus starts to reveal a comprehensive sketch of dietary zinc absorption and its regulatory control, a process that is still incompletely understood in mammalian organisms. The knowledge gained will act as a reference for future mammalian studies, and also enable an appreciation of this important process from an evolutionary perspective. PMID:24063361

  20. Zinc triggers microglial activation.

    PubMed

    Kauppinen, Tiina M; Higashi, Youichirou; Suh, Sang Won; Escartin, Carole; Nagasawa, Kazuki; Swanson, Raymond A

    2008-05-28

    Microglia are resident immune cells of the CNS. When stimulated by infection, tissue injury, or other signals, microglia assume an activated, "ameboid" morphology and release matrix metalloproteinases, reactive oxygen species, and other proinflammatory factors. This innate immune response augments host defenses, but it can also contribute to neuronal death. Zinc is released by neurons under several conditions in which microglial activation occurs, and zinc chelators can reduce neuronal death in animal models of cerebral ischemia and neurodegenerative disorders. Here, we show that zinc directly triggers microglial activation. Microglia transfected with a nuclear factor-kappaB (NF-kappaB) reporter gene showed a severalfold increase in NF-kappaB activity in response to 30 microm zinc. Cultured mouse microglia exposed to 15-30 microm zinc increased nitric oxide production, increased F4/80 expression, altered cytokine expression, and assumed the activated morphology. Zinc-induced microglial activation was blocked by inhibiting NADPH oxidase, poly(ADP-ribose) polymerase-1 (PARP-1), or NF-kappaB activation. Zinc injected directly into mouse brain induced microglial activation in wild-type mice, but not in mice genetically lacking PARP-1 or NADPH oxidase activity. Endogenous zinc release, induced by cerebral ischemia-reperfusion, likewise induced a robust microglial reaction, and this reaction was suppressed by the zinc chelator CaEDTA. Together, these results suggest that extracellular zinc triggers microglial activation through the sequential activation of NADPH oxidase, PARP-1, and NF-kappaB. These findings identify a novel trigger for microglial activation and a previously unrecognized mechanism by which zinc may contribute to neurological disorders.

  1. Rupture prématurée des membranes à terme: facteurs pronostiques et conséquences néonatales

    PubMed Central

    Yasmina, Asmama; Barakat, Amina

    2017-01-01

    La rupture prématurée des membranes (RPM) à terme survient dans 5 à 10% des grossesses. Elle rend compte d'une part importante de morbidité et de mortalité néonatales. Le but de cette étude est de déterminer les facteurs pronostiques maternels et obstétricaux ainsi que le devenir des nouveau-nés à terme issus d'une grossesse compliquée de rupture prématurée des membranes ayant été hospitalisés au service ou gérés à la consultation externe. Etude rétrospective, analysant toutes les observations de nouveau-nés à terme issus de grossesses compliquées de RPM, enregistrées au service de néonatologie de l'hôpital d'enfants de Rabat entre le 1er janvier et le 31 juillet 2014. Au cours de la période d'étude nous avons colligé 144 cas de RPM isolée sur un total de 2400 naissances vivantes (NV) soit une prévalence de 6% NV, répartis comme suit : 06 cas de RPM (4%) entre 6 et 12 heures, 14 cas (9,7%) entre 12 et 18 heures, 28 cas (19,4%) entre 18 et 24 heures et 96 cas (66,6%) supérieure à 24 heures. La majorité de nos parturientes étaient dans la tranche d'âge de 25 à 35ans avec un taux de 52%. Une chorioamniotite associée a été retenue dans 8,3% des cas. Les parturientes ont été mises sous antibiothérapie prophylactique par voie orale ou parentérale dans 28% des cas, avec un liquide amniotique clair dans 81% des cas. Le diagnostic d'IMF probable a été retenu dans 46 cas dont 65.2 % dans le sous groupesupérieur à 18 h versus respectivement 26% et 8,7% dans les sous groupe 12 à 18 h et inférieur à 12 h. A l'admission, on a noté une prédominance masculine avec 58,3%, les nouveau-nés étaient asymptomatiques dans 76% des cas et ils présentaient une détresse respiratoire dans 42,8% des cas, un ictère dans 31,45% des cas, une fièvre dans 14,2% des cas et des signes de souffrance neurologique dans 11,5% des cas. Tous les nouveau-nés hospitalisés, soit dans 72% des cas, ont été mis sous antibiothérapie pendant une

  2. Environmental Conditions of Surface Soils and Biomass Prevailing in the Training Area at CFB Gagetown, New Brunswick

    DTIC Science & Technology

    2003-09-26

    sur Ia caracterisation environnementale de leurs secteurs d’entrainement majeurs afin d’ameliorer les connaissances des impacts de tous les types...et geographique. En 2001, Ia premiere phase de cette etude a consiste en la caracterisation hydrogeologique partielle dans la portion nord du...secteur d’entrainement. Cette premiere phase a implique le forage de 42 puits, afin de caracteriser la dynamique et la qualite des eaux souterraines. En

  3. Effet de la teneur en carbone sur la resistance du CA6NM a la propagation des fissures de fatigue

    NASA Astrophysics Data System (ADS)

    Akhiate, Aziz

    L'amelioration des performances des roues de turbines hydrauliques a fait l'objet de plusieurs etudes. Dans ce memoire, on s'est interesse a l'effet de la teneur en carbone du materiau de base de type CA6NM des aubes de turbines sur la microstructure et les proprietes mecaniques en general et en particulier sur le comportement en fatigue propagation. De maniere a bien atteindre cet objectif, on a choisi trois differentes nuances d'acier a faible 0.018% C, moyenne 0.033% C et elevee 0.067% C teneurs en carbone. Le 0.018% C et 0.067% C ont ete fabriques par le meme facturier et ils ont subi des traitements thermiques differents. De meme, le 0.033% C a subi des traitements thermiques differents des deux autres apres avoir ete coule par un autre fabricant. Afin d'effacer l'historique des traitements thermiques prealablement effectues et d'avoir la meme taille de grains parents austenitiques (GPA), on a austenitise les trois nuances d'acier a la meme temperature 1040°C, a differentes periodes suivant la teneur en carbone. Apres avoir homogeneise la GPA, on a entame le revenu. Le carbone a une influence sur la microstructure revenue notamment la quantite d'austenite de reversion ainsi que sur sa stabilite thermique et mecanique. Pour mettre en evidence l'effet de la teneur en carbone, on a trouve raisonnable d'isoler les effets relies a la temperature de revenu, en particulier la formation d'austenite de reversion. En effet, on a choisi deux temperatures de revenu. La premiere temperature est a 550°C pendant 2h imposee aux trois materiaux afin d'avoir une microstructure sans austenite de reversion. La deuxieme temperature choisie est a 610°C pour avoir un maximum et une identique quantite d'austenite de reversion sans presence de martensite fraiche. A la lumiere de ces deux microstructures, nous pouvons etablir une relation entre les proprietes mecaniques du CA6NM et la teneur en carbone, ainsi qu'entre les effets de la presence ou non d'austenite de reversion sur les

  4. The Potential for Zinc Stable Isotope Techniques and Modelling to Determine Optimal Zinc Supplementation

    PubMed Central

    Tran, Cuong D.; Gopalsamy, Geetha L.; Mortimer, Elissa K.; Young, Graeme P.

    2015-01-01

    It is well recognised that zinc deficiency is a major global public health issue, particularly in young children in low-income countries with diarrhoea and environmental enteropathy. Zinc supplementation is regarded as a powerful tool to correct zinc deficiency as well as to treat a variety of physiologic and pathologic conditions. However, the dose and frequency of its use as well as the choice of zinc salt are not clearly defined regardless of whether it is used to treat a disease or correct a nutritional deficiency. We discuss the application of zinc stable isotope tracer techniques to assess zinc physiology, metabolism and homeostasis and how these can address knowledge gaps in zinc supplementation pharmacokinetics. This may help to resolve optimal dose, frequency, length of administration, timing of delivery to food intake and choice of zinc compound. It appears that long-term preventive supplementation can be administered much less frequently than daily but more research needs to be undertaken to better understand how best to intervene with zinc in children at risk of zinc deficiency. Stable isotope techniques, linked with saturation response and compartmental modelling, also have the potential to assist in the continued search for simple markers of zinc status in health, malnutrition and disease. PMID:26035248

  5. Zinc Information

    MedlinePlus

    ... for Eye Conditions Clinical Digest: Hepatitis C and Dietary Supplements Related Resources From Other Agencies Age-Related Eye Disease Study 2 (AREDS2) ( NEI ) Can Zinc Be Harmful? ( ODS ) Zinc ( ODS ) Follow NCCIH: Read our disclaimer ...

  6. Zinc starvation induces autophagy in yeast

    PubMed Central

    Kawamata, Tomoko; Horie, Tetsuro; Matsunami, Miou; Sasaki, Michiko; Ohsumi, Yoshinori

    2017-01-01

    Zinc is an essential nutrient for all forms of life. Within cells, most zinc is bound to protein. Because zinc serves as a catalytic or structural cofactor for many proteins, cells must maintain zinc homeostasis under severely zinc-deficient conditions. In yeast, the transcription factor Zap1 controls the expression of genes required for uptake and mobilization of zinc, but to date the fate of existing zinc-binding proteins under zinc starvation remains poorly understood. Autophagy is an evolutionarily conserved cellular degradation/recycling process in which cytoplasmic proteins and organelles are sequestered for degradation in the vacuole/lysosome. In this study, we investigated how autophagy functions under zinc starvation. Zinc depletion induced non-selective autophagy, which is important for zinc-limited growth. Induction of autophagy by zinc starvation was not directly related to transcriptional activation of Zap1. Instead, TORC1 inactivation directed zinc starvation-induced autophagy. Abundant zinc proteins, such as Adh1, Fba1, and ribosomal protein Rpl37, were degraded in an autophagy-dependent manner. But the targets of autophagy were not restricted to zinc-binding proteins. When cellular zinc is severely depleted, this non-selective autophagy plays a role in releasing zinc from the degraded proteins and recycling zinc for other essential purposes. PMID:28264932

  7. Studies on the bioavailability of zinc in humans: intestinal interaction of tin and zinc.

    PubMed

    Solomons, N W; Marchini, J S; Duarte-Favaro, R M; Vannuchi, H; Dutra de Oliveira, J E

    1983-04-01

    Mineral/mineral interactions at the intestinal level are important in animal nutrition and toxicology, but only limited understanding of their extent or importance in humans has been developed. An inhibitory interaction of dietary tin on zinc retention has been recently described from human metabolic studies. We have explored the tin/zinc interaction using the change-in-plasma-zinc-concentration method with a standard dosage of 12.5 mg of zinc as zinc sulfate in 100 ml of Coca-Cola. Sn/Zn ratios of 2:1, 4:1, and 8:1, constituted by addition of 25, 50, and 100 mg of tin as stannous chloride, had no significant overall effect on zinc uptake. The 100-mg dose of tin produced noxious gastrointestinal symptoms. Addition of iron as ferrous sulfate to form ratios of Sn/Fe/Zn of 1:1:1 and 2:2:1 with the standard zinc solution and the appropriate doses of tin produced a reduction of zinc absorption not dissimilar from that seen previously with zinc and iron alone, and addition of picolinic acid did not influence the uptake of zinc from the solution with the 2:2:1 Sn/Fe/Zn ratio.

  8. Suppression of zinc dendrites in zinc electrode power cells

    NASA Technical Reports Server (NTRS)

    Damjanovic, A.; Diggle, J. W.

    1970-01-01

    Addition of various tetraalkyl quarternary ammonium salts, to alkaline zincate electrolyte of cell, prevents formation of zinc dendrites during charging of zinc electrode. Electrode capacity is not impaired and elimination of dendrites prolongs cell life.

  9. Zinc triggers microglial activation

    PubMed Central

    Kauppinen, Tiina M.; Higashi, Youichirou; Suh, Sang Won; Escartin, Carole; Nagasawa, Kazuki; Swanson, Raymond A.

    2009-01-01

    Microglia are resident immune cells of the central nervous system. When stimulated by infection, tissue injury, or other signals, microglia assume an activated, “amoeboid” morphology and release matrix metalloproteinases, reactive oxygen species, and other pro-inflammatory factors. This innate immune response augments host defenses, but it can also contribute to neuronal death. Zinc is released by neurons under several conditions in which microglial activation occurs, and zinc chelators can reduce neuronal death in animal models of cerebral ischemia and neurodegenerative disorders. Here we show that zinc directly triggers microglial activation. Microglia transfected with an NF-kB reporter gene showed a several-fold increase in NF-kB activity in response to 30 μM zinc. Cultured mouse microglia exposed to 15 – 30 μM zinc increased nitric oxide production, increased F4/80 expression, altered cytokine expression, and assumed the activated morphology. Zinc-induced microglial activation was blocked by inhibiting NADPH oxidase, poly(ADP-ribose) polymerase-1 (PARP-1), or NF-κB activation. Zinc injected directly into mouse brain induced microglial activation in wild-type mice, but not in mice genetically lacking PARP-1 or NADPH oxidase activity. Endogenous zinc release, induced by cerebral ischemia-reperfusion, likewise induced a robust microglial reaction, and this reaction was suppressed by the zinc chelator CaEDTA. Together, these results suggest that extracellular zinc triggers microglial activation through the sequential activation of NADPH oxidase, PARP-1, and NF-κB. These findings identify a novel trigger for microglial activation and a previously unrecognized mechanism by which zinc may contribute to neurological disorders. PMID:18509044

  10. Zinc starvation induces autophagy in yeast.

    PubMed

    Kawamata, Tomoko; Horie, Tetsuro; Matsunami, Miou; Sasaki, Michiko; Ohsumi, Yoshinori

    2017-05-19

    Zinc is an essential nutrient for all forms of life. Within cells, most zinc is bound to protein. Because zinc serves as a catalytic or structural cofactor for many proteins, cells must maintain zinc homeostasis under severely zinc-deficient conditions. In yeast, the transcription factor Zap1 controls the expression of genes required for uptake and mobilization of zinc, but to date the fate of existing zinc-binding proteins under zinc starvation remains poorly understood. Autophagy is an evolutionarily conserved cellular degradation/recycling process in which cytoplasmic proteins and organelles are sequestered for degradation in the vacuole/lysosome. In this study, we investigated how autophagy functions under zinc starvation. Zinc depletion induced non-selective autophagy, which is important for zinc-limited growth. Induction of autophagy by zinc starvation was not directly related to transcriptional activation of Zap1. Instead, TORC1 inactivation directed zinc starvation-induced autophagy. Abundant zinc proteins, such as Adh1, Fba1, and ribosomal protein Rpl37, were degraded in an autophagy-dependent manner. But the targets of autophagy were not restricted to zinc-binding proteins. When cellular zinc is severely depleted, this non-selective autophagy plays a role in releasing zinc from the degraded proteins and recycling zinc for other essential purposes. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

  11. Supplemental levels of iron and calcium interfere with repletion of zinc status in zinc-deficient animals.

    PubMed

    Jayalakshmi, S; Platel, Kalpana

    2016-05-18

    Negative interactions between minerals interfering with each other's absorption are of concern when iron and calcium supplements are given to pregnant women and children. We have previously reported that supplemental levels of iron and calcium inhibit the bioaccessibility of zinc, and compromise zinc status in rats fed diets with high levels of these two minerals. The present study examined the effect of supplemental levels of iron and calcium on the recovery of zinc status during a zinc repletion period in rats rendered zinc-deficient. Iron and calcium, both individually and in combination, significantly interfered with the recovery of zinc status in zinc deficient rats during repletion with normal levels of zinc in the diet. Rats maintained on diets containing supplemental levels of these two minerals had significantly lower body weight, and the concentration of zinc in serum and organs was significantly lower than in zinc-deficient rats not receiving the supplements. Iron and calcium supplementation also significantly inhibited the activity of zinc-containing enzymes in the serum as well as liver. Both iron and calcium independently exerted this negative effect on zinc status, while their combination seemed to have a more prominent effect, especially on the activities of zinc containing enzymes. This investigation is probably the first systematic study on the effect of these two minerals on the zinc status of zinc deficient animals and their recovery during repletion with normal amounts of zinc.

  12. [Zinc and chronic enteropathies].

    PubMed

    Giorgi, P L; Catassi, C; Guerrieri, A

    1984-01-01

    In recent years the nutritional importance of zinc has been well established; its deficiency and its symptoms have also been recognized in humans. Furthermore, Acrodermatitis Enteropathica has been isolated, a rare but severe disease, of which skin lesions, chronic diarrhoea and recurring infections are the main symptoms. The disease is related to the malfunctioning of intestinal absorption of zinc and can be treated by administering pharmacological doses of zinc orally. Good dietary sources of zinc are meat, fish and, to a less extent, human milk. The amount of zinc absorbed in the small intestine is influenced by other nutrients: some compounds inhibit this process (dietary fiber, phytate) while others (picolinic acid, citric acid), referred to as Zn-binding ligands (ZnBL) facilitate it. Citric acid is thought to be the ligand which accounts for the high level of bioavailability of zinc in human milk. zinc absorption occurs throughout the small intestine, not only in the prossimal tract (duodenum and jejunum) but also in the distal tract (ileum). Diarrhoea is one of the clinical manifestations of zinc deficiency, thus many illnesses distinguished by chronic diarrhoea entail a bad absorption of zinc. In fact, in some cases of chronic enteropathies in infants, like coeliac disease and seldom cystic fibrosis, a deficiency of zinc has been isolated. Some of the symptoms of Crohn's disease, like retarded growth and hypogonadism, have been related to hypozinchemia which is present in this illness. Finally, it is possible that some of the dietary treatments frequently used for persistent post-enteritis diarrhoea (i.e. cow's milk exclusion, abuse and misuse of dietary fiber like carrot and carub powder, use of soy formula) can constitute a scarce supply of zinc and therefore could promote the persistency of diarrhoea itself.

  13. Zinc oxyfluoride transparent conductor

    DOEpatents

    Gordon, Roy G.

    1991-02-05

    Transparent, electrically conductive and infrared-reflective films of zinc oxyfluoride are produced by chemical vapor deposition from vapor mixtures of zinc, oxygen and fluorine-containing compounds. The substitution of fluorine for some of the oxygen in zinc oxide results in dramatic increases in the electrical conductivity. For example, diethyl zinc, ethyl alcohol and hexafluoropropene vapors are reacted over a glass surface at 400.degree. C. to form a visibly transparent, electrically conductive, infrared reflective and ultraviolet absorptive film of zinc oxyfluoride. Such films are useful in liquid crystal display devices, solar cells, electrochromic absorbers and reflectors, energy-conserving heat mirrors, and antistatic coatings.

  14. Zinc Extraction from Zinc Plants Residue Using Selective Alkaline Leaching and Electrowinning

    NASA Astrophysics Data System (ADS)

    Ashtari, Pedram; Pourghahramani, Parviz

    2015-10-01

    Annually, a great amount of zinc plants residue is produced in Iran. One of them is hot filter cake (known as HFC) which can be used as a secondary resource of zinc, cobalt and manganese. Unfortunately, despite its heavy metal content, the HFC is not treated. For the first time, zinc was selectively leached from HFC employing alkaline leaching. Secondly, leaching was optimized to achieve maximum recovery using this method. Effects of factors like NaOH concentration (C = 3, 5, 7 and 9 M), temperature (T = 50, 70, 90 and 105 °C), solid/liquid ratio (weight/volume, S/L = 1/10 and 1/5 W/V) and stirring speed (R = 500 and 800 rpm) were studied on HFC leaching. L16 orthogonal array (OA, two factors in four levels and two factors in two levels) was applied to determine the optimum condition and the most significant factor affecting the overall zinc extraction. As a result, maximum zinc extraction was 83.4 %. Afterwards, a rough test was conducted for zinc electrowinning from alkaline solution according to the common condition available in literature by which pure zinc powder (99.96 %) was successfully obtained.

  15. Effect of resveratrol and zinc on intracellular zinc status in normal human prostate epithelial cells

    USDA-ARS?s Scientific Manuscript database

    To evaluate the influence of resveratrol on cellular zinc status, normal human prostate epithelial (NHPrE) cells were treated with 6 levels of resveratrol (0, 0.5, 1, 2.5, 5 and 10 microM) and 4 levels of zinc [0, 4, 16, and 32 microM for zinc-deficient (ZD), zinc-normal (ZN), zinc-adequate (ZA), an...

  16. Le recours aux modeles dans l'enseignement de la biologie au secondaire : Conceptions d'enseignantes et d'enseignants et modes d'utilisation

    NASA Astrophysics Data System (ADS)

    Varlet, Madeleine

    Le recours aux modeles et a la modelisation est mentionne dans la documentation scientifique comme un moyen de favoriser la mise en oeuvre de pratiques d'enseignement-apprentissage constructivistes pour pallier les difficultes d'apprentissage en sciences. L'etude prealable du rapport des enseignantes et des enseignants aux modeles et a la modelisation est alors pertinente pour comprendre leurs pratiques d'enseignement et identifier des elements dont la prise en compte dans les formations initiale et disciplinaire peut contribuer au developpement d'un enseignement constructiviste des sciences. Plusieurs recherches ont porte sur ces conceptions sans faire de distinction selon les matieres enseignees, telles la physique, la chimie ou la biologie, alors que les modeles ne sont pas forcement utilises ou compris de la meme maniere dans ces differentes disciplines. Notre recherche s'est interessee aux conceptions d'enseignantes et d'enseignants de biologie au secondaire au sujet des modeles scientifiques, de quelques formes de representations de ces modeles ainsi que de leurs modes d'utilisation en classe. Les resultats, que nous avons obtenus au moyen d'une serie d'entrevues semi-dirigees, indiquent que globalement leurs conceptions au sujet des modeles sont compatibles avec celle scientifiquement admise, mais varient quant aux formes de representations des modeles. L'examen de ces conceptions temoigne d'une connaissance limitee des modeles et variable selon la matiere enseignee. Le niveau d'etudes, la formation prealable, l'experience en enseignement et un possible cloisonnement des matieres pourraient expliquer les differentes conceptions identifiees. En outre, des difficultes temporelles, conceptuelles et techniques peuvent freiner leurs tentatives de modelisation avec les eleves. Toutefois, nos resultats accreditent l'hypothese que les conceptions des enseignantes et des enseignants eux-memes au sujet des modeles, de leurs formes de representation et de leur approche

  17. Zinc and gastrointestinal disease

    PubMed Central

    Skrovanek, Sonja; DiGuilio, Katherine; Bailey, Robert; Huntington, William; Urbas, Ryan; Mayilvaganan, Barani; Mercogliano, Giancarlo; Mullin, James M

    2014-01-01

    This review is a current summary of the role that both zinc deficiency and zinc supplementation can play in the etiology and therapy of a wide range of gastrointestinal diseases. The recent literature describing zinc action on gastrointestinal epithelial tight junctions and epithelial barrier function is described. Zinc enhancement of gastrointestinal epithelial barrier function may figure prominently in its potential therapeutic action in several gastrointestinal diseases. PMID:25400994

  18. Properties of Zip4 accumulation during zinc deficiency and its usefulness to evaluate zinc status: a study of the effects of zinc deficiency during lactation.

    PubMed

    Hashimoto, Ayako; Nakagawa, Miki; Tsujimura, Natsuki; Miyazaki, Shiho; Kizu, Kumiko; Goto, Tomoko; Komatsu, Yusuke; Matsunaga, Ayu; Shirakawa, Hitoshi; Narita, Hiroshi; Kambe, Taiho; Komai, Michio

    2016-03-01

    Systemic and cellular zinc homeostasis is elaborately controlled by ZIP and ZnT zinc transporters. Therefore, detailed characterization of their expression properties is of importance. Of these transporter proteins, Zip4 functions as the primarily important transporter to control systemic zinc homeostasis because of its indispensable function of zinc absorption in the small intestine. In this study, we closely investigated Zip4 protein accumulation in the rat small intestine in response to zinc status using an anti-Zip4 monoclonal antibody that we generated and contrasted this with the zinc-responsive activity of the membrane-bound alkaline phosphatase (ALP). We found that Zip4 accumulation is more rapid in response to zinc deficiency than previously thought. Accumulation increased in the jejunum as early as 1 day following a zinc-deficient diet. In the small intestine, Zip4 protein expression was higher in the jejunum than in the duodenum and was accompanied by reduction of ALP activity, suggesting that the jejunum can become zinc deficient more easily. Furthermore, by monitoring Zip4 accumulation levels and ALP activity in the duodenum and jejunum, we reasserted that zinc deficiency during lactation may transiently alter plasma glucose levels in the offspring in a sex-specific manner, without affecting homeostatic control of zinc metabolism. This confirms that zinc nutrition during lactation is extremely important for the health of the offspring. These results reveal that rapid Zip4 accumulation provides a significant conceptual advance in understanding the molecular basis of systemic zinc homeostatic control, and that properties of Zip4 protein accumulation are useful to evaluate zinc status closely. Copyright © 2016 the American Physiological Society.

  19. Interaction Between Yeasts and Zinc

    NASA Astrophysics Data System (ADS)

    Nicola, Raffaele De; Walker, Graeme

    Zinc is an essential trace element in biological systems. For example, it acts as a cellular membrane stabiliser, plays a critical role in gene expression and genome modification and activates nearly 300 enzymes, including alcohol dehydrogenase. The present chapter will be focused on the influence of zinc on cell physiology of industrial yeast strains of Saccharomyces cerevisiae, with special regard to the uptake and subsequent utilisation of this metal. Zinc uptake by yeast is metabolism-dependent, with most of the available zinc translocated very quickly into the vacuole. At cell division, zinc is distributed from mother to daughter cells and this effectively lowers the individual cellular zinc concentration, which may become zinc depleted at the onset of the fermentation. Zinc influences yeast fermentative performance and examples will be provided relating to brewing and wine fermentations. Industrial yeasts are subjected to several stresses that may impair fermentation performance. Such stresses may also impact on yeast cell zinc homeostasis. This chapter will discuss the practical implications for the correct management of zinc bioavailability for yeast-based biotechnologies aimed at improving yeast growth, viability, fermentation performance and resistance to environmental stresses

  20. Bush v. Bin Laden: Effect of State Emotion on Perceived Threat is Mediated by Emotion Towards the Threat Agent (Bush vs. Ben Laden: l’Effet de l’Emotion etat sur la Menace Percue est Mediatisees par l’Emotion vis-a-vis de l’Agent Menacant)

    DTIC Science & Technology

    2009-07-01

    auteurs discu- tent des implications des resultats pour les theories qui postulent un effet de I’emotion sur la perception du risque et pour com...effect of global negative emotion on perceived threat . The authors discuss implications of the findings for theories that postulate an effect of... auteurs ont mene une etude perception j emotion j experimentale afin d’examiner les effets d’etats emotionnels Specifi- ques (peur et colere) et globaux

  1. Investigation experimentale de l'ecoulement et des performances thermiques du nanofluide eau-oxyde de cuivre dans un Micro-Canal Chauffe

    NASA Astrophysics Data System (ADS)

    Rimbault, Benjamin

    Cette these de maitrise presentee par articles visait a etudier le comportement hydraulique et thermique d'un ecoulement de nanofluides en micro-canal chauffe. Nous avons etudie premierement de l'eau distillee, ensuite des melanges de particules d'oxyde de cuivre (taille 29nm) avec de l'eau distillee en concentrations particulaires volumiques 4.5%, 1.03%, et 0.24% (CuO-H2O). L'ecoulement force des differents fluides a ete realise au moyen de pompes a engrenages au sein d'un circuit ferme, comprenant un micro-canal a section rectangulaire (e=1.116mm,1=25.229mm) chauffe sur deux faces paralleles via des cartouches electriques, deux echangeurs de chaleurs en serie, ainsi qu'un debitmetre magnetique. A notre connaissance peu d'etudes sur l'ecoulement de nanofluides d'oxyde de cuivre-eau en micro-canal rectangulaire chauffe sont disponibles dans la litterature, cette recherche sert de contribution. Premierement, une validation avec la litterature a ete effectuee pour le cas d'un ecoulement d'eau entre plaques planes paralleles chauffees. Des essais hydrauliques ont ete realises pour une gamme du nombre de Reynolds allant jusqu'a Re=5000 a temperature constante. Par la suite des essais thermiques jusqu'a Re=2500 ont consiste en une elevation de temperature fixe (20.5°C a 30.5°C) a travers la longueur du micro-canal sous un regime stationnaire. Les resultats ont demontre une augmentation de la perte de pression et du coefficient de frottement des nanofluides sur l'eau pour un meme debit. Une telle augmentation de perte de pression etait de +70%, +25%, et +0 a 30% respectivement pour les concentrations 4.50%, 1.03%, et 0.24%. Concernant la transition laminaire a turbulent les comportements semblaient indiquer une valeur critique semblable entre l'eau et les differentes concentrations avec et sans chauffage a un nombre de Reynolds critique Rem 1000. Nous avons observe une legere augmentation du coefficient de convection thermique avec le debit massique pour les faibles

  2. Enhanced zinc consumption causes memory deficits and increased brain levels of zinc

    USGS Publications Warehouse

    Flinn, J.M.; Hunter, D.; Linkous, D.H.; Lanzirotti, A.; Smith, L.N.; Brightwell, J.; Jones, B.F.

    2005-01-01

    Zinc deficiency has been shown to impair cognitive functioning, but little work has been done on the effects of elevated zinc. This research examined the effect on memory of raising Sprague-Dawley rats on enhanced levels of zinc (10 ppm ZnCO3; 0.153 mM) in the drinking water for periods of 3 or 9 months, both pre- and postnatally. Controls were raised on lab water. Memory was tested in a series of Morris Water Maze (MWM) experiments, and zinc-treated rats were found to have impairments in both reference and working memory. They were significantly slower to find a stationary platform and showed greater thigmotaxicity, a measure of anxiety. On a working memory task, where the platform was moved each day, zinc-treated animals had longer latencies over both trials and days, swam further from the platform, and showed greater thigmotaxicity. On trials using an Atlantis platform, which remained in one place but was lowered on probe trials, the zinc-treated animals had significantly fewer platform crossings, spent less time in the target quadrant, and did not swim as close to the platform position. They had significantly greater latency on nonprobe trials. Microprobe synchrotron X-ray fluorescence (??SXRF) confirmed that brain zinc levels were increased by adding ZnCO 3 to the drinking water. These data show that long-term dietary administration of zinc can lead to impairments in cognitive function. ?? 2004 Elsevier Inc. All rights reserved.

  3. Analyse des interactions energetiques entre un arena et son systeme de refrigeration

    NASA Astrophysics Data System (ADS)

    Seghouani, Lotfi

    La presente these s'inscrit dans le cadre d'un projet strategique sur les arenas finance par le CRSNG (Conseil de Recherche en Sciences Naturelles et en Genie du Canada) qui a pour but principal le developpement d'un outil numerique capable d'estimer et d'optimiser la consommation d'energie dans les arenas et curlings. Notre travail s'inscrit comme une suite a un travail deja realise par DAOUD et coll. (2006, 2007) qui a developpe un modele 3D (AIM) en regime transitoire de l'arena Camilien Houde a Montreal et qui calcule les flux de chaleur a travers l'enveloppe du batiment ainsi que les distributions de temperatures et d'humidite durant une annee meteorologique typique. En particulier, il calcule les flux de chaleur a travers la couche de glace dus a la convection, la radiation et la condensation. Dans un premier temps nous avons developpe un modele de la structure sous la glace (BIM) qui tient compte de sa geometrie 3D, des differentes couches, de l'effet transitoire, des gains de chaleur du sol en dessous et autour de l'arena etudie ainsi que de la temperature d'entree de la saumure dans la dalle de beton. Par la suite le BIM a ete couple le AIM. Dans la deuxieme etape, nous avons developpe un modele du systeme de refrigeration (REFSYS) en regime quasi-permanent pour l'arena etudie sur la base d'une combinaison de relations thermodynamiques, de correlations de transfert de chaleur et de relations elaborees a partir de donnees disponibles dans le catalogue du manufacturier. Enfin le couplage final entre l'AIM +BIM et le REFSYS a ete effectue sous l'interface du logiciel TRNSYS. Plusieurs etudes parametriques on ete entreprises pour evaluer les effets du climat, de la temperature de la saumure, de l'epaisseur de la glace, etc. sur la consommation energetique de l'arena. Aussi, quelques strategies pour diminuer cette consommation ont ete etudiees. Le considerable potentiel de recuperation de chaleur au niveau des condenseurs qui peut reduire l'energie requise par

  4. [Advances in the research of zinc deficiency and zinc supplementation treatment in patients with severe burns].

    PubMed

    Wang, X X; Zhang, M J; Li, X B

    2018-01-20

    Zinc is one of the essential trace elements in human body, which plays an important role in regulating acute inflammatory response, glucose metabolism, anti-oxidation, immune and gastrointestinal function of patients with severe burns. Patients with severe burns may suffer from zinc deficiency because of insufficient amount of zinc intake from the diet and a large amount of zinc lose through wounds and urine. Zinc deficiency may affect their wound healing process and prognosis. This article reviews the characteristics of zinc metabolism in patients with severe burns through dynamic monitoring the plasma and urinary concentration of zinc. An adequate dosage of zinc supplemented to patients with severe burns by an appropriate method can increase the level of zinc in plasma and skin tissue and improve wound healing, as well as reduce the infection rates and mortality. At the same time, it is important to observe the symptoms and signs of nausea, dizziness, leukopenia and arrhythmia in patients with severe burns after supplementing excessive zinc.

  5. 99. ZINC ROUGHER CELLS ON LEFT, ZINC CLEANER CELLS ON ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    99. ZINC ROUGHER CELLS ON LEFT, ZINC CLEANER CELLS ON RIGHT, LOOKING NORTH. NOTE ONE STYLE OF DENVER AGITATOR IN LOWER RIGHT CELL. - Shenandoah-Dives Mill, 135 County Road 2, Silverton, San Juan County, CO

  6. Serum thymulin in human zinc deficiency.

    PubMed Central

    Prasad, A S; Meftah, S; Abdallah, J; Kaplan, J; Brewer, G J; Bach, J F; Dardenne, M

    1988-01-01

    The activity of thymulin (a thymic hormone) is dependent on the presence of zinc in the molecule. We assayed serum thymulin activity in three models of mildly zinc-deficient (ZD) human subjects before and after zinc supplementation: (a) two human volunteers in whom a specific and mild zinc deficiency was induced by dietary means; (b) six mildly ZD adult sickle cell anemia (SCA) subjects; and (c) six mildly ZD adult non-SCA subjects. Their plasma zinc levels were normal and they showed no overt clinical manifestations of zinc deficiency. The diagnosis of mild zinc deficiency was based on the assay of zinc in lymphocytes, granulocytes, and platelets. Serum thymulin activity was decreased as a result of mild zinc deficiency and was corrected by in vivo and in vitro zinc supplementation, suggesting that this parameter was a sensitive indicator of zinc deficiency in humans. An increase in T101-, sIg-cells, decrease in T4+/T8+ ratio, and decreased IL 2 activity were observed in the experimental human model during the zinc depletion phase, all of which were corrected after repletion with zinc. Similar changes in lymphocyte subpopulation, correctable with zinc supplementation, were also observed in mildly ZD SCA subjects. Inasmuch as thymulin is known to induce intra- and extrathymic T cell differentiation, our studies provide a possible mechanism for the role of zinc on T cell functions. Images PMID:3262625

  7. Zinc supplementation in public health.

    PubMed

    Penny, Mary Edith

    2013-01-01

    Zinc is necessary for physiological processes including defense against infections. Zinc deficiency is responsible for 4% of global child morbidity and mortality. Zinc supplements given for 10-14 days together with low-osmolarity oral rehydration solution (Lo-ORS) are recommended for the treatment of childhood diarrhea. In children aged ≥ 6 months, daily zinc supplements reduce the duration of acute diarrhea episodes by 12 h and persistent diarrhea by 17 h. Zinc supplements could reduce diarrhea mortality in children aged 12-59 months by an estimated 23%; they are very safe but are associated with an increase in vomiting especially with the first dose. Heterogeneity between the results of trials is not understood but may be related to dose and the etiology of the diarrhea infection. Integration of zinc and Lo-ORS into national programs is underway but slowly, procurement problems are being overcome and the greatest challenge is changing health provider and caregiver attitudes to diarrhea management. Fewer trials have been conducted of zinc adjunct therapy in severe respiratory tract infections and there is as yet insufficient evidence to recommend addition of zinc to antibiotic therapy. Daily zinc supplements for all children >12 months of age in zinc deficient populations are estimated to reduce diarrhea incidence by 11-23%. The greatest impact is in reducing multiple episodes of diarrhea. The effect on duration of diarrheal episodes is less clear, but there may be up to 9% reduction. Zinc is also efficacious in reducing dysentery and persistent diarrhea. Zinc supplements may also prevent pneumonia by about 19%, but heterogeneity across studies has not yet been explained. When analyses are restricted to better quality studies using CHERG (Child Health Epidemiology Reference Group) methodology, zinc supplements are estimated to reduce diarrheal deaths by 13% and pneumonia deaths by 20%. National-level programs to combat childhood zinc deficiency should be

  8. History of Zinc in Agriculture12

    PubMed Central

    Nielsen, Forrest H.

    2012-01-01

    Zinc was established as essential for green plants in 1926 and for mammals in 1934. However, >20 y would pass before the first descriptions of zinc deficiencies in farm animals appeared. In 1955, it was reported that zinc supplementation would cure parakeratosis in swine. In 1958, it was reported that zinc deficiency induced poor growth, leg abnormalities, poor feathering, and parakeratosis in chicks. In the 1960s, zinc supplementation was found to alleviate parakeratosis in grazing cattle and sheep. Within 35 y, it was established that nearly one half of the soils in the world may be zinc deficient, causing decreased plant zinc content and production that can be prevented by zinc fertilization. In many of these areas, zinc deficiency is prevented in grazing livestock by zinc fertilization of pastures or by providing salt licks. For livestock under more defined conditions, such as poultry, swine, and dairy and finishing cattle, feeds are easily supplemented with zinc salts to prevent deficiency. Today, the causes and consequences of zinc deficiency and methods and effects of overcoming the deficiency are well established for agriculture. The history of zinc in agriculture is an outstanding demonstration of the translation of research into practical application. PMID:23153732

  9. Endogenous Zinc in Neurological Diseases

    PubMed Central

    2005-01-01

    The use of zinc in medicinal skin cream was mentioned in Egyptian papyri from 2000 BC (for example, the Smith Papyrus), and zinc has apparently been used fairly steadily throughout Roman and modern times (for example, as the American lotion named for its zinc ore, 'Calamine'). It is, therefore, somewhat ironic that zinc is a relatively late addition to the pantheon of signal ions in biology and medicine. However, the number of biological functions, health implications and pharmacological targets that are emerging for zinc indicate that it might turn out to be 'the calcium of the twenty-first century'. Here neurobiological roles of endogenous zinc is summarized. PMID:20396459

  10. Measurements of zinc absorption: application and interpretation in research designed to improve human zinc nutriture.

    PubMed

    Hambidge, K Michael; Miller, Leland V; Tran, Cuong D; Krebs, Nancy F

    2005-11-01

    The focus of this paper is on the application of measurements of zinc absorption in human research, especially studies designed to assess the efficacy of intervention strategies to prevent and manage zinc deficiency in populations. Emphasis is given to the measurement of quantities of zinc absorbed rather than restricting investigations to measurements of fractional absorption of zinc. This is especially important when determining absorption of zinc from the diet, whether it be the habitual diet or an intervention diet under evaluation. Moreover, measurements should encompass all meals for a minimum of one day with the exception of some pilot studies. Zinc absorption is primarily via an active saturable transport process into the enterocytes of the proximal small intestine. The relationship between quantity of zinc absorbed and the quantity ingested is best characterized by saturable binding models. When applied to human studies that have sufficient data to examine dose-response relationships, efficiency of absorption is high until approximately 50-60% maximal absorption is achieved, even with moderate phytate intakes. This also coincides approximately with the quantity of absorbed zinc necessary to meet physiologic requirements. Efficiency of absorption with intakes that exceed this level is low or very low. These observations have important practical implications for the design and interpretation of intervention studies to prevent zinc deficiency. They also suggest the potential utility of measurements of the quantity of zinc absorbed when evaluating the zinc status of populations.

  11. Interaction of zinc with dental mineral.

    PubMed

    Ingram, G S; Horay, C P; Stead, W J

    1992-01-01

    As some currently available toothpastes contain zinc compounds, the reaction of zinc with dental mineral and its effect on crystal growth rates were studied using three synthetic calcium-deficient hydroxyapatites (HAP) as being representative of dental mineral. Zinc was readily acquired by all HAP samples in the absence of added calcium, the amount adsorbed being proportional to the HAP surface area; about 9 mumol Zn/m2 was adsorbed at high zinc concentrations. As zinc was acquired, calcium was released, consistent with 1:1 Ca:Zn exchange. Soluble calcium reduced zinc uptake and similarly, calcium post-treatment released zinc. Pretreatment of HAP with 0.5 mM zinc reduced its subsequent ability to undergo seeded crystal growth, as did extracts of a toothpaste containing 0.5% zinc citrate, even in the presence of saliva. The reverse reaction, i.e. displacement of adsorbed zinc by salivary levels of calcium, however, indicates the mechanism by which zinc can reduce calculus formation in vivo by inhibiting plaque mineralisation without adversely affecting the anti-caries effects of fluoride.

  12. Rechargeable zinc cell with alkaline electrolyte which inhibits shape change in zinc electrode

    DOEpatents

    Adler, T.C.; McLarnon, F.R.; Cairns, E.J.

    1994-04-12

    An improved rechargeable zinc cell is described comprising a zinc electrode and another electrode such as, for example, a nickel-containing electrode, and having an electrolyte containing KOH and a combination of KF and K[sub 2]CO[sub 3] salts which inhibits shape change in the zinc electrode, i.e., the zinc electrode exhibits low shape change, resulting in an improved capacity retention of the cell over an number of charge-discharge cycles, while still maintaining high discharge rate characteristics. 8 figures.

  13. Rechargeable zinc cell with alkaline electrolyte which inhibits shape change in zinc electrode

    DOEpatents

    Adler, Thomas C.; McLarnon, Frank R.; Cairns, Elton J.

    1994-01-01

    An improved rechargeable zinc cell is described comprising a zinc electrode and another electrode such as, for example, a nickel-containing electrode, and having an electrolyte containing KOH and a combination of KF and K.sub.2 CO.sub.3 salts which inhibits shape change in the zinc electrode, i.e., the zinc electrode exhibits low shape change, resulting in an improved capacity retention of the cell over an number of charge-discharge cycles, while still maintaining high discharge rate characteristics.

  14. Leptin, NPY, Melatonin and Zinc Levels in Experimental Hypothyroidism and Hyperthyroidism: The Relation to Zinc.

    PubMed

    Baltaci, Abdulkerim Kasım; Mogulkoc, Rasim

    2017-06-01

    Since zinc mediates the effects of many hormones or is found in the structure of numerous hormone receptors, zinc deficiency leads to various functional impairments in the hormone balance. And also thyroid hormones have important activity on metabolism and feeding. NPY and leptin are affective on food intake and regulation of appetite. The present study is conducted to determine how zinc supplementation and deficiency affect thyroid hormones (free and total T3 and T4), melatonin, leptin, and NPY levels in thyroid dysfunction in rats. The experiment groups in the study were formed as follows: Control (C); Hypothyroidism (PTU); Hypothyroidism+Zinc (PTU+Zn); Hypothyroidism+Zinc deficient; Hyperthyroidism (H); Hyperthyroidism+Zinc (H+Zn); and Hyperthyroidism+Zinc deficient. Thyroid hormone parameters (FT 3 , FT 4 , TT 3 , and TT 4 ) were found to be reduced in hypothyroidism groups and elevated in the hyperthyroidism groups. Melatonin values increased in hyperthyroidism and decreased in hypothyroidism. Leptin and NPY levels both increased in hypo- and hyperthyroidism. Zinc levels, on the other hand, decreased in hypothyroidism and increased in hyperthyroidism. Zinc supplementation, particularly when thyroid function is impaired, has been demonstrated to markedly prevent these changes.

  15. Zinc as a Gatekeeper of Immune Function

    PubMed Central

    Wessels, Inga; Maywald, Martina; Rink, Lothar

    2017-01-01

    After the discovery of zinc deficiency in the 1960s, it soon became clear that zinc is essential for the function of the immune system. Zinc ions are involved in regulating intracellular signaling pathways in innate and adaptive immune cells. Zinc homeostasis is largely controlled via the expression and action of zinc “importers” (ZIP 1–14), zinc “exporters” (ZnT 1–10), and zinc-binding proteins. Anti-inflammatory and anti-oxidant properties of zinc have long been documented, however, underlying mechanisms are still not entirely clear. Here, we report molecular mechanisms underlying the development of a pro-inflammatory phenotype during zinc deficiency. Furthermore, we describe links between altered zinc homeostasis and disease development. Consequently, the benefits of zinc supplementation for a malfunctioning immune system become clear. This article will focus on underlying mechanisms responsible for the regulation of cellular signaling by alterations in zinc homeostasis. Effects of fast zinc flux, intermediate “zinc waves”, and late homeostatic zinc signals will be discriminated. Description of zinc homeostasis-related effects on the activation of key signaling molecules, as well as on epigenetic modifications, are included to emphasize the role of zinc as a gatekeeper of immune function. PMID:29186856

  16. Uptake and partitioning of zinc in Lemnaceae.

    PubMed

    Lahive, Elma; O'Callaghan, Michael J A; Jansen, Marcel A K; O'Halloran, John

    2011-11-01

    Macrophytes provide food and shelter for aquatic invertebrates and fish, while also acting as reservoirs for nutrients and trace elements. Zinc accumulation has been reported for various Lemnaceae species. However, comparative accumulation across species and the link between zinc accumulation and toxicity are poorly understood. Morphological distribution and cellular storage, in either bound or soluble form, are important for zinc tolerance. This study shows differences in the uptake and accumulation of zinc by three duckweed species. Landoltia punctata and Lemna minor generally accumulated more zinc than Lemna gibba. L. minor, but not L. gibba or L. punctata, accumulated greater concentrations of zinc in roots compared to fronds when exposed to high levels of zinc. The proportion of zinc stored in the bound form relative to the soluble-form was higher in L. minor. L. punctata accumulated greater concentrations of zinc in fronds compared to roots and increased the proportion of zinc it stored in the soluble form, when exposed to high zinc levels. L. gibba is the only species that significantly accumulated zinc at low concentrations, and was zinc-sensitive. Overall, internal zinc concentrations showed no consistent correlation with toxic effect. We conclude that relationships between zinc toxicity and uptake and accumulation are species specific reflecting, among others, zinc distribution and storage. Differences in zinc distribution and storage are also likely to have implications for zinc bioavailability and trophic mobility.

  17. The General Formulation and Practical Calculation of the Diffusion Coefficient in a Lattice Containing Cavities; FORMULATION GENERALE ET CALCUL PRATIQUE DU COEFFICIENT DE DIFFUSION DANS UN RESEAU COMPORTANT DES CAVITES (in French)

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Benoist, P.

    The calculation of diffusion coefficients in a lattice necessitates the knowledge of a correct method of weighting the free paths of the different constituents. An unambiguous definition of this weighting method is given here, based on the calculation of leakages from a zone of a reactor. The formulation obtained, which is both simple and general, reduces the calculation of diffusion coefficients to that of collision probabilities in the different media; it reveals in the expression for the radial coefficient the series of the terms of angular correlation (cross terms) recently shown by several authors. This formulation is then used tomore » calculate the practical case of a classical type of lattice composed of a moderator and a fuel element surrounded by an empty space. Analytical and numerical comparison of the expressions obtained with those inferred from the theory of BEHRENS shows up the importance of several new terms some of which are linked with the transparency of the fuel element. Cross terms up to the second order are evaluated. A practical formulary is given at the end of the paper. (author) [French] Le calcul des coefficients de diffusion dans un reseau suppose la connaissance d'un mode de ponderation correct des libres parcours des differents constituants. On definit ici sans ambiguite ce mode de ponderation a partir du calcul des fuites hors d'une zone de reacteur. La formulation obtenue, simple et generale, ramene le calcul des coefficients de diffusion a celui des probabilites de collision dans les differents milieux; elle fait apparaitre dans l'expression du coefficient radial la serie des termes de correlation angulaire (termes rectangles), mis en evidence recemment par plusieurs auteurs. Cette formulation est ensuite appliquee au calcul pratique d'un reseau classique, compose d'un moderateur et d'un element combustible entoure d'une cavite; la comparaison analytique et numerique des expressions obtenues avec celles deduites de la theorie de

  18. Zinc: an essential but elusive nutrient123

    PubMed Central

    King, Janet C

    2011-01-01

    Zinc is essential for multiple aspects of metabolism. Physiologic signs of zinc depletion are linked with diverse biochemical functions rather than with a specific function, which makes it difficult to identify biomarkers of zinc nutrition. Nutrients, such as zinc, that are required for general metabolism are called type 2 nutrients. Protein and magnesium are examples of other type 2 nutrients. Type 1 nutrients are required for one or more specific functions: examples include iron, vitamin A, iodine, folate, and copper. When dietary zinc is insufficient, a marked reduction in endogenous zinc loss occurs immediately to conserve the nutrient. If zinc balance is not reestablished, other metabolic adjustments occur to mobilize zinc from small body pools. The location of those pools is not known, but all cells probably have a small zinc reserve that includes zinc bound to metallothionein or zinc stored in the Golgi or in other organelles. Plasma zinc is also part of this small zinc pool that is vulnerable to insufficient intakes. Plasma zinc concentrations decline rapidly with severe deficiencies and more moderately with marginal depletion. Unfortunately, plasma zinc concentrations also decrease with a number of conditions (eg, infection, trauma, stress, steroid use, after a meal) due to a metabolic redistribution of zinc from the plasma to the tissues. This redistribution confounds the interpretation of low plasma zinc concentrations. Biomarkers of metabolic zinc redistribution are needed to determine whether this redistribution is the cause of a low plasma zinc rather than poor nutrition. Measures of metallothionein or cellular zinc transporters may fulfill that role. PMID:21715515

  19. Fiabilité des structures mécaniques adaptatives: effet de la panne des actionneurs ou des capteurs sur la stabilité

    NASA Astrophysics Data System (ADS)

    Fall, H.; Charon, W.; Kouta, R.

    2002-12-01

    Ces dernières décennies, des activités significatives dans le monde étaient dirigées autour du contrôle actif. Le but de ces recherches était essentiellement d'améliorer les performances, la fiabilité et la sécurité des systèmes. Notamment dans le cas des structures soumises à des vibrations aléatoires. D'importants travaux ont été consacré à l'utilisation des “matériaux intelligents” comme capteurs et actionneurs. Cette article propose l'analyse de la fiabilité des systèmes mécaniques en étudiant les pannes des actionneurs ou des capteurs. L'effet de ces pannes sur la stabilité et la performance du système y est démontré. Les méthodologies de conception y sont rappelées. Des exemples numériques sont fournis à travers le contrôle d'un panneau sous chargement dynamique pour illustrer la méthode proposée.

  20. Effect of short-term zinc supplementation on zinc and selenium tissue distribution and serum antioxidant enzymes.

    PubMed

    Skalny, Andrey A; Tinkov, Alexey A; Medvedeva, Yulia S; Alchinova, Irina B; Karganov, Mikhail Y; Skalny, Anatoly V; Nikonorov, Alexandr A

    2015-01-01

    A significant association between Zn and Se homeostasis exists. At the same time, data on the influence of zinc supplementation on selenium distribution in organs and tissues seem to be absent. Therefore, the primary objective of the current study is to investigate the influence of zinc asparaginate supplementation on zinc and selenium distribution and serum superoxide dismutase (SOD) and glutathione peroxidase (GPx) activity in Wistar rats. 36 rats were used in the experiment. The duration of the experiment was 7 and 14 days in the first and second series, respectively. The rats in Group I were used as the control ones. Animals in Groups II and III daily obtained zinc asparaginate (ZnA) in the doses of 5 and 15 mg/kg weight, respectively. Zinc and selenium content in liver, kidneys, heart, muscle, serum and hair was assessed using inductively coupled plasma mass spectrometry. Serum SOD and GPx activity was analysed spectrophotometrically using Randox kits. Intragastric administration of zinc asparaginate significantly increased liver, kidney, and serum zinc content without affecting skeletal and cardiac muscle levels. Zinc supplementation also stimulated selenium retention in the rats' organs. Moreover, a significant positive correlation between zinc and selenium content was observed. Finally, zinc asparaginate treatment has been shown to modulate serum GPx but not SOD activity. The obtained data indicate that zinc-induced increase in GPx activity may be mediated through modulation of selenium status. However, future studies are required to estimate the exact mechanisms of zinc and selenium interplay.

  1. Zinc oxide overdose

    MedlinePlus

    Zinc oxide is an ingredient in many products. Some of these are certain creams and ointments used ... prevent or treat minor skin burns and irritation. Zinc oxide overdose occurs when someone eats one of ...

  2. Selective Acidic Leaching of Spent Zinc-Carbon Batteries Followed by Zinc Electrowinning

    NASA Astrophysics Data System (ADS)

    Shalchian, Hossein; Rafsanjani-Abbasi, Ali; Vahdati-Khaki, Jalil; Babakhani, Abolfazl

    2015-02-01

    In this work, a selective acidic leaching procedure was employed for recycling zinc from spent zinc-carbon batteries. Leaching experiments were carried out in order to maximize zinc recovery and minimize manganese recovery in diluted sulfuric acid media. Response surface methodology and analysis of variance were employed for experimental design, data analysis, and leaching optimization. The experimental design has 28 experiments that include 24 main runs and four replicate in center point. The optimal conditions obtained from the selective acidic leaching experiments, were sulfuric acid concentration of 1 pct v/v, leaching temperature of 343 K (70 °C), pulp density of 8 pct w/v, and stirring speed of 300 rpm. The results show that the zinc and manganese recoveries after staged selective leaching are about 92 and 15 pct, respectively. Finally, metallic zinc with purity of 99.9 pct and electrolytic manganese dioxide were obtained by electrowinning.

  3. Bioavailability of Zinc in Wistar Rats Fed with Rice Fortified with Zinc Oxide

    PubMed Central

    Della Lucia, Ceres Mattos; Santos, Laura Luiza Menezes; Rodrigues, Kellen Cristina da Cruz; Rodrigues, Vivian Cristina da Cruz; Martino, Hércia Stampini Duarte; Pinheiro Sant’Ana, Helena Maria

    2014-01-01

    The study of zinc bioavailability in foods is important because this mineral intake does not meet the recommended doses for some population groups. Also, the presence of dietary factors that reduce zinc absorption contributes to its deficiency. Rice fortified with micronutrients (Ultra Rice®) is a viable alternative for fortification since this cereal is already inserted into the population habit. The aim of this study was to evaluate the bioavailability of zinc (Zn) in rice fortified with zinc oxide. During 42 days, rats were divided into four groups and fed with diets containing two different sources of Zn (test diet: UR® fortified with zinc oxide, or control diet: zinc carbonate (ZnCO3)), supplying 50% or 100%, respectively, of the recommendations of this mineral for animals. Weight gain, food intake, feed efficiency ratio, weight, thickness and length of femur; retention of zinc, calcium (Ca) and magnesium (Mg) in the femur and the concentrations of Zn in femur, plasma and erythrocytes were evaluated. Control diet showed higher weight gain, feed efficiency ratio, retention of Zn and Zn concentration in the femur (p < 0.05). However, no differences were observed (p > 0.05) for dietary intake, length and thickness of the femur, erythrocyte and plasmatic Zn between groups. Although rice fortified with zinc oxide showed a lower bioavailability compared to ZnCO3, this food can be a viable alternative to be used as a vehicle for fortification. PMID:24932657

  4. Zinc finger proteins in cancer progression.

    PubMed

    Jen, Jayu; Wang, Yi-Ching

    2016-07-13

    Zinc finger proteins are the largest transcription factor family in human genome. The diverse combinations and functions of zinc finger motifs make zinc finger proteins versatile in biological processes, including development, differentiation, metabolism and autophagy. Over the last few decades, increasing evidence reveals the potential roles of zinc finger proteins in cancer progression. However, the underlying mechanisms of zinc finger proteins in cancer progression vary in different cancer types and even in the same cancer type under different types of stress. Here, we discuss general mechanisms of zinc finger proteins in transcription regulation and summarize recent studies on zinc finger proteins in cancer progression. In this review, we also emphasize the importance of further investigations in elucidating the underlying mechanisms of zinc finger proteins in cancer progression.

  5. 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.

  6. Developpement des betons semi autoplacants a rheologie adaptee pour des infrastructures

    NASA Astrophysics Data System (ADS)

    Sotomayor Cruz, Cristian Daniel

    Au cours des dernières décennies, les infrastructures canadiennes et québécoises comportent plusieurs structures en béton armé présentant des problèmes de durabilité dus aux conditions climatiques sévères, à la mauvaise conception des structures, à la qualité des matériaux, aux types des bétons choisis, aux systèmes de construction ou à l'existence d'événements incontrôlables. En ce qui concerne le choix du béton pour la construction des infrastructures, une vaste gamme de béton divisée en deux principaux types peut être utilisée: le béton conventionnel vibré (BCV) et le béton autoplaçant (BAP). Dans le cas d'un BCV, la consolidation inadéquate par vibration a été un problème récurrent, occasionnant des dommages structuraux. Ceci a conduit à une réduction de la durabilité et à une augmentation du coût d'entretien et de réparation des infrastructures. Rien que l'utilisation d'un BAP a des avantages tels que l'élimination de la vibration, la réduction des coûts de main d'oeuvre et l'amélioration de la qualité des structures, néanmoins, le coût initial d'un BAP par rapport à un BCV ne permet pas encore de généraliser son utilisation dans l'industrie de la construction. Ce mémoire présente la conception d'une nouvelle gamme de béton semi-autoplaçant pour la construction des infrastructures (BSAP-I) exigeant une vibration minimale. Il s'agit de trouver un équilibre optimal entre la rhéologie et le coût initial du nouveau béton pour conférer une bonne performance structurale et économique aux structures. Le programme expérimental établi a premièrement permis d'évaluer la faisabilité d'utilisation des BSAP-I pour la mise en place des piliers d'une infrastructure de pont à Sherbrooke. En plus, l'utilisation d'un plan d'expériences a permis l'évaluation de trois paramètres de formulation sur les propriétés des mélanges de BSAP-I à l'état frais et durci. Finalement, l'évaluation de la performance des

  7. Effect of zinc gluconate, sage oil on inflammatory patterns and hyperglycemia in zinc deficient diabetic rats.

    PubMed

    Elseweidy, Mohamed M; Ali, Abdel-Moniem A; Elabidine, Nabila Zein; Mursey, Nada M

    2017-11-01

    The relationship between zinc homeostasis and pancreatic function had been established. In this study we aimed firstly to configure the inflammatory pattern and hyperglycemia in zinc deficient diabetic rats. Secondly to illustrate the effect of two selected agents namely Zinc gluconate and sage oil (Salvia Officinalis, family Lamiaceae). Rats were fed on Zinc deficient diet, deionized water for 28days along with Zinc level check up at intervals to achieve zinc deficient state then rats were rendered diabetic through receiving one dose of alloxan monohydrate (120mg/kg) body weight, classified later into 5 subgroups. Treatment with sage oil (0.042mg/kg IP) and Zinc gluconate orally (150mg/kg) body weight daily for 8 weeks significantly reduced serum glucose, C-reactive protein (CRP), Tumor necrosis factor alpha (TNF- α), interleukins-6 1 β, inflammatory8 (IFN ȣ), pancreatic 1L1-β along with an increase in serum Zinc and pancreatic Zinc transporter 8 (ZNT8). Histopathological results of pancreatic tissues showed a good correlation with the biochemical findings. Both sage oil and zinc gluconate induced an improvement in the glycemic and inflammatory states. This may be of value like the therapeutic agent for diabetes. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

  8. Paternité des articles et intérêts concurrents : une analyse des recommandations aux auteurs des journaux traitant de pratique pharmaceutique

    PubMed Central

    Courbon, Ève; Tanguay, Cynthia; Lebel, Denis; Bussières, Jean-François

    2014-01-01

    RÉSUMÉ Contexte : La présence d’auteurs honorifiques et fantômes ainsi que les intérêts concurrents représentent des difficultés bien documentées, liées à la publication d’articles scientifiques. Il existe des lignes directrices encadrant la rédaction et la publication de manuscrits scientifiques, notamment celles de l’International Committee of Medical Journal Editors (ICMJE). Objectifs : L’objectif principal de cette étude descriptive et transversale visait à recenser les instructions portant sur la paternité des articles et les intérêts concurrents provenant des recommandations aux auteurs des journaux traitant de pratique pharmaceutique. L’objectif secondaire visait à déterminer des mesures correctrices pour une paternité des articles plus transparente. Méthode : La recherche a débuté par l’identification des journaux traitant de pratique pharmaceutique. La consultation des instructions aux auteurs des journaux a permis ensuite de recenser les recommandations destinées à éviter les problèmes de paternité des articles et d’intérêts concurrents. Finalement, les membres de l’équipe de recherche se sont consultés afin de définir des mesures correctrices possibles à l’intention des chercheurs. Résultats : Des 232 journaux traitant de pharmacie, 33 ont été définis comme traitant de pratique pharmaceutique. Un total de 24 (73 %) journaux mentionnaient suivre la politique de l’ICMJE, 14 (42 %) demandaient aux auteurs de remplir un formulaire de déclaration d’intérêts concurrents au moment de la soumission de l’article, 17 (52 %) présentaient une définition de la qualité d’auteur et 5 (15 %) demandaient de détailler les contributions de chaque auteur. Une grille de 40 critères a été élaborée pour définir l’attribution du statut d’auteur. Conclusion : Moins de la moitié des journaux demandait aux auteurs de transmettre un formulaire de déclaration des intérêts concurrents au moment de la

  9. hZIP1 zinc uptake transporter down regulation and zinc depletion in prostate cancer

    PubMed Central

    Franklin, Renty B; Feng, Pei; Milon, B; Desouki, Mohamed M; Singh, Keshav K; Kajdacsy-Balla, André; Bagasra, Omar; Costello, Leslie C

    2005-01-01

    Background The genetic and molecular mechanisms responsible for and associated with the development and progression of prostate malignancy are largely unidentified. The peripheral zone is the major region of the human prostate gland where malignancy develops. The normal peripheral zone glandular epithelium has the unique function of accumulating high levels of zinc. In contrast, the ability to accumulate zinc is lost in the malignant cells. The lost ability of the neoplastic epithelial cells to accumulate zinc is a consistent factor in their development of malignancy. Recent studies identified ZIP1 (SLC39A1) as an important zinc transporter involved in zinc accumulation in prostate cells. Therefore, we investigated the possibility that down-regulation of hZIP1 gene expression might be involved in the inability of malignant prostate cells to accumulate zinc. To address this issue, the expression of hZIP1 and the depletion of zinc in malignant versus non-malignant prostate glands of prostate cancer tissue sections were analyzed. hZIP1 expression was also determined in malignant prostate cell lines. Results hZIP1 gene expression, ZIP1 transporter protein, and cellular zinc were prominent in normal peripheral zone glandular epithelium and in benign hyperplastic glands (also zinc accumulating glands). In contrast, hZIP1 gene expression and transporter protein were markedly down-regulated and zinc was depleted in adenocarcinomatous glands and in prostate intra-epithelial neoplastic foci (PIN). These changes occur early in malignancy and are sustained during its progression in the peripheral zone. hZIP1 is also expressed in the malignant cell lines LNCaP, PC-3, DU-145; and in the nonmalignant cell lines HPr-1 and BPH-1. Conclusion The studies clearly establish that hZIP1 gene expression is down regulated and zinc is depleted in adenocarcinomatous glands. The fact that all the malignant cell lines express hZIP1 indicates that the down-regulation in adenocarcinomatous

  10. Designing Hydrolytic Zinc Metalloenzymes

    PubMed Central

    2015-01-01

    Zinc is an essential element required for the function of more than 300 enzymes spanning all classes. Despite years of dedicated study, questions regarding the connections between primary and secondary metal ligands and protein structure and function remain unanswered, despite numerous mechanistic, structural, biochemical, and synthetic model studies. Protein design is a powerful strategy for reproducing native metal sites that may be applied to answering some of these questions and subsequently generating novel zinc enzymes. From examination of the earliest design studies introducing simple Zn(II)-binding sites into de novo and natural protein scaffolds to current studies involving the preparation of efficient hydrolytic zinc sites, it is increasingly likely that protein design will achieve reaction rates previously thought possible only for native enzymes. This Current Topic will review the design and redesign of Zn(II)-binding sites in de novo-designed proteins and native protein scaffolds toward the preparation of catalytic hydrolytic sites. After discussing the preparation of Zn(II)-binding sites in various scaffolds, we will describe relevant examples for reengineering existing zinc sites to generate new or altered catalytic activities. Then, we will describe our work on the preparation of a de novo-designed hydrolytic zinc site in detail and present comparisons to related designed zinc sites. Collectively, these studies demonstrate the significant progress being made toward building zinc metalloenzymes from the bottom up. PMID:24506795

  11. Quantitative mapping of zinc fluxes in the mammalian egg reveals the origin of fertilization-induced zinc sparks

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Que, Emily L.; Bleher, Reiner; Duncan, Francesca E.

    2014-12-15

    Fertilization of a mammalian egg initiates a series of 'zinc sparks' that are necessary to induce the egg-to-embryo transition. Despite the importance of these zinc-efflux events little is known about their origin. To understand the molecular mechanism of the zinc spark we combined four physical approaches that resolve zinc distributions in single cells: a chemical probe for dynamic live-cell fluorescence imaging and a combination of scanning transmission electron microscopy with energy-dispersive spectroscopy, X-ray fluorescence microscopy and three-dimensional elemental tomography for high-resolution elemental mapping. We show that the zinc spark arises from a system of thousands of zinc-loaded vesicles, each ofmore » which contains, on average, 10(6) zinc atoms. These vesicles undergo dynamic movement during oocyte maturation and exocytosis at the time of fertilization. The discovery of these vesicles and the demonstration that zinc sparks originate from them provides a quantitative framework for understanding how zinc fluxes regulate cellular processes« less

  12. Quantitative mapping of zinc fluxes in the mammalian egg reveals the origin of fertilization-induced zinc sparks.

    PubMed

    Que, Emily L; Bleher, Reiner; Duncan, Francesca E; Kong, Betty Y; Gleber, Sophie C; Vogt, Stefan; Chen, Si; Garwin, Seth A; Bayer, Amanda R; Dravid, Vinayak P; Woodruff, Teresa K; O'Halloran, Thomas V

    2015-02-01

    Fertilization of a mammalian egg initiates a series of 'zinc sparks' that are necessary to induce the egg-to-embryo transition. Despite the importance of these zinc-efflux events little is known about their origin. To understand the molecular mechanism of the zinc spark we combined four physical approaches that resolve zinc distributions in single cells: a chemical probe for dynamic live-cell fluorescence imaging and a combination of scanning transmission electron microscopy with energy-dispersive spectroscopy, X-ray fluorescence microscopy and three-dimensional elemental tomography for high-resolution elemental mapping. We show that the zinc spark arises from a system of thousands of zinc-loaded vesicles, each of which contains, on average, 10(6) zinc atoms. These vesicles undergo dynamic movement during oocyte maturation and exocytosis at the time of fertilization. The discovery of these vesicles and the demonstration that zinc sparks originate from them provides a quantitative framework for understanding how zinc fluxes regulate cellular processes.

  13. Quantitative mapping of zinc fluxes in the mammalian egg reveals the origin of fertilization-induced zinc sparks

    DOE PAGES

    Que, Emily L.; Bleher, Reiner; Duncan, Francesca E.; ...

    2014-12-15

    Fertilization of a mammalian egg induces a series of ‘zinc sparks’ that are necessary for inducing the egg-to-embryo transition. Despite the importance of these zinc efflux events little is known about their origin. To understand the molecular mechanism of the zinc spark we combined four physical approaches to resolve zinc distributions in single cells: a chemical probe for dynamic live-cell fluorescence imaging and a combination of scanning transmission electron microscopy with energy dispersive spectroscopy, X-ray fluorescence microscopy, and 3D elemental tomography for high resolution elemental mapping. Here we show that the zinc spark arises from a system of thousands ofmore » zinc-loaded vesicles, each of which contains, on average, 106 zinc atoms. These vesicles undergo dynamic movement during oocyte maturation and exocytosis at the time of fertilization. We conclude that the discovery of these vesicles and the demonstration that zinc sparks originate from them provides a quantitative framework for understanding how zinc fluxes regulate cellular processes.« less

  14. Quantitative mapping of zinc fluxes in the mammalian egg reveals the origin of fertilization-induced zinc sparks

    PubMed Central

    Que, Emily L.; Bleher, Reiner; Duncan, Francesca E.; Kong, Betty Y.; Gleber, Sophie C.; Vogt, Stefan; Chen, Si; Garwin, Seth A.; Bayer, Amanda R.; Dravid, Vinayak; Woodruff, Teresa K.; O’Halloran, Thomas V.

    2015-01-01

    Fertilization of a mammalian egg induces a series of ‘zinc sparks’ that are necessary for inducing the egg-to-embryo transition. Despite the importance of these zinc efflux events little is known about their origin. To understand the molecular mechanism of the zinc spark we combined four physical approaches to resolve zinc distributions in single cells: a chemical probe for dynamic live-cell fluorescence imaging and a combination of scanning transmission electron microscopy with energy dispersive spectroscopy, X-ray fluorescence microscopy, and 3D elemental tomography for high resolution elemental mapping. We show that the zinc spark arises from a system of thousands of zinc-loaded vesicles, each of which contains, on average, 106 zinc atoms. These vesicles undergo dynamic movement during oocyte maturation and exocytosis at the time of fertilization. The discovery of these vesicles and the demonstration that zinc sparks originate from them provides a quantitative framework for understanding how zinc fluxes regulate cellular processes. PMID:25615666

  15. 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

  16. Etude du strabisme chez des enfants de 0 à 15 ans suivis a Lubumbashi, République Démocratique du Congo: analyse des aspects épidémiologiques et cliniques

    PubMed Central

    Bienvenu, Yogolelo Asani; Angel, Musau Nkola; Sebastien, Mbuyi Musanzayi; Philippe, Cilundika Mulenga; Léon, Kabamba Ngombe; Eugene, Twite Kabange; Chami, Cham Lubamba; Prosper, Kalenga Muenze Kayamba; Claude, Speeg-Schatz; Gaby, Chenge Borasisi

    2015-01-01

    Introduction Le strabisme est défini comme un syndrome à double composante: motrice et sensorielle. Le but de ce travail est de décrire les aspects épidémiologiques et cliniques du strabisme chez l'enfant congolais de 0 à 15 ans dans la ville de Lubumbashi. Méthodes Il s'agit d'une étude descriptive longitudinale sur les aspects épidémiologiques et cliniques du strabisme chez l'enfant congolais de 0 à 15 ans dans la ville de Lubumbashi entre Décembre 2012 à Décembre 2013. Nous avons recueilli l’âge des patients, leur sexe, leur provenance, le type de strabisme, la réfraction, le fond d'oeil, les antécédents (hérédité) ainsi que le type de la déviation strabique observé sur 70 patients. Résultats Nous avons observé 70 cas de strabisme manifeste dont 31 cas (44,28%) étaient dans la tranche d’âge comprise entre 0 et 5 ans. L’âge moyen de nos patients était de 6,7 ans avec une prédominance du sexe féminin, soit 51,42%. Le strabisme était convergent dans 65,71%, divergent dans 30%, et vertical dans 4,28%. Les ésotropies représentaient 65 cas (92,85%), quatre cas (5,71%) avaient un antécédent familial de strabisme au premier degré de parenté, 21 cas (30%) au second degré de parenté, 45 cas (64,28%) n'avaient pas cet antécédent. L'oeil gauche était le plus dominé dans 30% des cas. Les facteurs favorisant le strabisme étaient inconnus dans 54 cas (77,14%). Le strabisme était secondaire à l'hypermétropie chez 32 patients (42,71%). Conclusion La fréquence du strabisme dans la ville de Lubumbashi chez les enfants âgés de 0 à 15 ans est de 0,50%. Comme dans la plupart des études sur le strabisme de l'enfant, c'est l’ésotropie qui est la déviation la plus commune. PMID:26834919

  17. Caracterisation des melanges developpes pour le moulage basse pression des poudres metalliques (LPIM) =

    NASA Astrophysics Data System (ADS)

    Fareh, Fouad

    Le moulage par injection basse pression des poudres metalliques est une technique de fabrication qui permet de fabriquer des pieces possedant la complexite des pieces coulees mais avec les proprietes mecaniques des pieces corroyees. Cependant, l'optimisation des etapes de deliantage et de frittage a ete jusqu'a maintenant effectuee a l'aide de melange pour lesquels la moulabilite optimale n'a pas encore ete demontree. Ainsi, la comprehension des proprietes rheologiques et de la segregation des melanges est tres limitee et cela presente le point faible du processus de LPIM. L'objectif de ce projet de recherche etait de caracteriser l'influence des liants sur le comportement rheologique des melanges en mesurant la viscosite et la segregation des melanges faible viscosite utilises dans le procede LPIM. Afin d'atteindre cet objectif, des essais rheologiques et thermogravimetriques ont ete conduits sur 12 melanges. Ces melanges ont ete prepares a base de poudre d'Inconel 718 de forme spherique (chargement solide constant a 60%) et de cires, d'agents surfactants ou epaississants. Les essais rheologiques ont ete utilises entre autre pour calculer l'indice d'injectabilite ?STV des melanges, tandis que les essais thermogravimetriques ont permis d'evaluer precisement la segregation des poudres dans les melanges. Il a ete demontre que les trois (3) melanges contenant de la cire de paraffine et de l'acide stearique presentent des indices alpha STV plus eleves qui sont avantageux pour le moulage par injection des poudres metalliques (MIM), mais segregent beaucoup trop pour que la piece fabriquee produise de bonnes caracteristiques mecaniques. A l'oppose, le melange contenant de la cire de paraffine et de l'ethylene-vinyle acetate ainsi que le melange contenant seulement de la cire de carnauba segregent peu voire pas du tout, mais possedent de tres faibles indices alphaSTV : ils sont donc difficilement injectables. Le meilleur compromis semble donc etre les melanges contenant de

  18. Developpement d'un montage simulant l'erosion par la pluie pour l'evaluation des revetements glaciophobes dans le domaine aerospatial

    NASA Astrophysics Data System (ADS)

    Tremblay, Sarah-Eve

    Ce memoire presente le developpement d’un montage simulant l’erosion par la pluie afin d’effectuer l’evaluation de differents revetements glaciophobes dans le domaine aerospatial. Bien que plusieurs revetements presentent une bonne efficacite a reduire l’adherence et/ou l’accumulation de glace, ils ne repondent pas necessairement aux normes de resistance a l’erosion simulee par les gouttes de pluie les frappant a grande vitesse. Il n’existe qu’une installation en Amerique du Nord offrant un service d’essai qui evalue la resistance a l’erosion par la pluie suivant les normes aerospatiales. Etant l’unique institution pouvant faire la certification de peintures utilisees sur les avions en ce qui a trait a l’erosion par la pluie, ce service est donc difficile d’acces et couteux. Le laboratoire international des materiaux antigivre (LIMA) a developpe un essai plus rapide et moins couteux, facilitant ainsi le developpement de revetements glaciophobes devant resister a l’erosion par la pluie. Dans cette etude, le developpement du montage d’erosion par la pluie effectue au laboratoire des materiaux antigivre (LIMA) est presente. En particulier, des essais sur quatre (4) revetements dont la resistance a l’erosion est connue, et sur trois revetements industriels, ont ete effectues afin d’ajuster les differents parametres du montage comme la pression et la temperature de l’eau ainsi que la robustesse du montage. Ensuite, des essais de sensibilite et de reproductibilite des resultats ont egalement ete effectues pour fin de validation du montage et du protocole experimental. Pour ce faire, le montage de type jet d’eau developpe consiste principalement en une pompe a haute pression qui projette un jet d’eau continu passant par les orifices d’un disque tournant. Cette operation permet de generer une goutte de pluie simulee qui est projetee sur un echantillon de revetement statique. L’essai est base sur la norme standard ASTM (Liquid

  19. La participation des enfants et des adolescents à la boxe

    PubMed Central

    Purcell, Laura K; LeBlanc, Claire MA

    2012-01-01

    RÉSUMÉ Des milliers de garçons et de filles de moins de 19 ans font de la boxe en Amérique du Nord. Même si la boxe comporte des avantages pour ceux qui y participent, y compris l’exercice, l’autodiscipline et la confiance en soi, le sport lui-même favorise et récompense des coups délibérés à la tête et au visage. Les personnes qui font de la boxe risquent de subir des blessures à la tête, au visage et au cou, y compris des traumatismes neurologiques chroniques et même fatals. Les commotions cérébrales sont l’une des principales blessures causées par la boxe. En raison du risque de blessures crâniennes et faciales, la Société canadienne de pédiatrie et l’American Academy of Pediatrics s’opposent vigoureusement à la boxe comme activité sportive pour les enfants et les adolescents. Ces organismes recommandent que les médecins s’élèvent contre la boxe auprès des jeunes et les encouragent à participer à d’autres activités dans lesquelles les coups intentionnels à la tête ne constituent pas un élément essentiel du sport.

  20. Prediction du profil de durete de l'acier AISI 4340 traite thermiquement au laser

    NASA Astrophysics Data System (ADS)

    Maamri, Ilyes

    Les traitements thermiques de surfaces sont des procedes qui visent a conferer au coeur et a la surface des pieces mecaniques des proprietes differentes. Ils permettent d'ameliorer la resistance a l'usure et a la fatigue en durcissant les zones critiques superficielles par des apports thermiques courts et localises. Parmi les procedes qui se distinguent par leur capacite en terme de puissance surfacique, le traitement thermique de surface au laser offre des cycles thermiques rapides, localises et precis tout en limitant les risques de deformations indesirables. Les proprietes mecaniques de la zone durcie obtenue par ce procede dependent des proprietes physicochimiques du materiau a traiter et de plusieurs parametres du procede. Pour etre en mesure d'exploiter adequatement les ressources qu'offre ce procede, il est necessaire de developper des strategies permettant de controler et regler les parametres de maniere a produire avec precision les caracteristiques desirees pour la surface durcie sans recourir au classique long et couteux processus essai-erreur. L'objectif du projet consiste donc a developper des modeles pour predire le profil de durete dans le cas de traitement thermique de pieces en acier AISI 4340. Pour comprendre le comportement du procede et evaluer les effets des differents parametres sur la qualite du traitement, une etude de sensibilite a ete menee en se basant sur une planification experimentale structuree combinee a des techniques d'analyse statistiques eprouvees. Les resultats de cette etude ont permis l'identification des variables les plus pertinentes a exploiter pour la modelisation. Suite a cette analyse et dans le but d'elaborer un premier modele, deux techniques de modelisation ont ete considerees, soient la regression multiple et les reseaux de neurones. Les deux techniques ont conduit a des modeles de qualite acceptable avec une precision d'environ 90%. Pour ameliorer les performances des modeles a base de reseaux de neurones, deux

  1. Zinc in Infection and Inflammation.

    PubMed

    Gammoh, Nour Zahi; Rink, Lothar

    2017-06-17

    Micronutrient homeostasis is a key factor in maintaining a healthy immune system. Zinc is an essential micronutrient that is involved in the regulation of the innate and adaptive immune responses. The main cause of zinc deficiency is malnutrition. Zinc deficiency leads to cell-mediated immune dysfunctions among other manifestations. Consequently, such dysfunctions lead to a worse outcome in the response towards bacterial infection and sepsis. For instance, zinc is an essential component of the pathogen-eliminating signal transduction pathways leading to neutrophil extracellular traps (NET) formation, as well as inducing cell-mediated immunity over humoral immunity by regulating specific factors of differentiation. Additionally, zinc deficiency plays a role in inflammation, mainly elevating inflammatory response as well as damage to host tissue. Zinc is involved in the modulation of the proinflammatory response by targeting Nuclear Factor Kappa B (NF-κB), a transcription factor that is the master regulator of proinflammatory responses. It is also involved in controlling oxidative stress and regulating inflammatory cytokines. Zinc plays an intricate function during an immune response and its homeostasis is critical for sustaining proper immune function. This review will summarize the latest findings concerning the role of this micronutrient during the course of infections and inflammatory response and how the immune system modulates zinc depending on different stimuli.

  2. The zinc paradigm for metalloneurochemistry.

    PubMed

    Barr, Chelsea A; Burdette, Shawn C

    2017-05-09

    Neurotransmission and sensory perception are shaped through metal ion-protein interactions in various brain regions. The term "metalloneurochemistry" defines the unique field of bioinorganic chemistry focusing on these processes, and zinc has been the leading target of metalloneurochemists in the almost 15 years since the definition was introduced. Zinc in the hippocampus interacts with receptors that dictate ion flow and neurotransmitter release. Understanding the intricacies of these interactions is crucial to uncovering the role that zinc plays in learning and memory. Based on receptor similarities and zinc-enriched neurons (ZENs) in areas of the brain responsible for sensory perception, such as the olfactory bulb (OB), and dorsal cochlear nucleus (DCN), zinc participates in odor and sound perception. Development and improvement of methods which allow for precise detection and immediate manipulation of zinc ions in neuronal cells and in brain slices will be critical in uncovering the synaptic action of zinc and, more broadly, the bioinorganic chemistry of cognition. © 2017 The Author(s). Published by Portland Press Limited on behalf of the Biochemical Society.

  3. Etude analytique du fonctionnement des moteurs à réluctance alimentés à fréquence variable

    NASA Astrophysics Data System (ADS)

    Sargos, F. M.; Gudefin, E. J.; Zaskalicky, P.

    1995-03-01

    In switched reluctance motors fed by a constant voltage source (like a battery) at high frequencies, the current becomes unpredictable and often cannot reach a given reference value, because of the variation of the inductances with the rotor position ; the “motional” m.m.f. generates commutation troubles which increase with the frequency. An optimal control as well as an approximate design of the motor require a quick and simple calculation of currents, powers and losses ; now, in principle, the non-linear electrical equation needs a numerical resolution, whose results cannot be extrapolated. By linearizing this equation by intervals, the method proposed here allows to express analytically, in any case, the phase currents, the torque and the copper losses, when the feeding voltage itself is constant by intervals. The model neglects saturation, but a simple adjustment of the inductance (chosen ad libitum) allows to deal with it. The calculation is immediate and perfectly accurate as long as the machine parameters themselves are well defined. Some results are given as examples for two usual feeding modes. Dans les machines à réluctance alimentées à haute fréquence par une source à tension constante, comme une batterie, le courant varie de manière difficilement prévisible, à cause de la variation des inductances avec la position du rotor, et souvent ne parvient pas à s'établir à une valeur de consigne imposée ; la f.é.m. “motionnelle” engendre des difficultés de communication qui s'aggravent avec l'augmentation de fréquence jusqu'à empêcher le fonctionnement. Tant pour optimiser la commande que pour dimensionner approximativement un moteur ; on doit pouvoir calculer simplement et rapidement le courant et la puissance ; or l'équation électrique, non linéaire, doit en principe être résolue numériquement et les résultats ne sont pratiquement pas extrapolables. En linéarisant par intervalles cette équation, la méthode proposée ici

  4. Mineral resource of the month: zinc

    USGS Publications Warehouse

    Tolcin, Amy C.

    2009-01-01

    The article provides information on zinc, the fourth most-widely consumed metal. It traces the first use of zinc with the Romans' production of brass. It describes the presence of zinc in Earth's crust and the importance of sphalerite as a source of zinc and other some minor metal production. The production and consumption of zinc as well as the commercial and industrial uses of this metal are also discussed.

  5. Zinc Therapy in Dermatology: A Review

    PubMed Central

    Mahajan, Vikram K.; Mehta, Karaninder S.; Chauhan, Pushpinder S.

    2014-01-01

    Zinc, both in elemental or in its salt forms, has been used as a therapeutic modality for centuries. Topical preparations like zinc oxide, calamine, or zinc pyrithione have been in use as photoprotecting, soothing agents or as active ingredient of antidandruff shampoos. Its use has expanded manifold over the years for a number of dermatological conditions including infections (leishmaniasis, warts), inflammatory dermatoses (acne vulgaris, rosacea), pigmentary disorders (melasma), and neoplasias (basal cell carcinoma). Although the role of oral zinc is well-established in human zinc deficiency syndromes including acrodermatitis enteropathica, it is only in recent years that importance of zinc as a micronutrient essential for infant growth and development has been recognized. The paper reviews various dermatological uses of zinc. PMID:25120566

  6. Interdependence of free zinc changes and protein complex assembly - insights into zinc signal regulation.

    PubMed

    Kocyła, Anna; Adamczyk, Justyna; Krężel, Artur

    2018-01-24

    Cellular zinc (Zn(ii)) is bound with proteins that are part of the proteomes of all domains of life. It is mostly utilized as a catalytic or structural protein cofactor, which results in a vast number of binding architectures. The Zn(ii) ion is also important for the formation of transient protein complexes with a Zn(ii)-dependent quaternary structure that is formed upon cellular zinc signals. The mechanisms by which proteins associate with and dissociate from Zn(ii) and the connection with cellular Zn(ii) changes remain incompletely understood. In this study, we aimed to examine how zinc protein domains with various Zn(ii)-binding architectures are formed under free Zn(ii) concentration changes and how formation of the Zn(ii)-dependent assemblies is related to the protein concentration and reactivity. To accomplish these goals we chose four zinc domains with different Zn(ii)-to-protein binding stoichiometries: classical zinc finger (ZnP), LIM domain (Zn 2 P), zinc hook (ZnP 2 ) and zinc clasp (ZnP 1 P 2 ) folds. Our research demonstrated a lack of changes in the saturation level of intraprotein zinc binding sites, despite various peptide concentrations, while homo- and heterodimers indicated a concentration-dependent tendency. In other words, at a certain free Zn(ii) concentration, the fraction of a formed dimeric complex increases or decreases with subunit concentration changes. Secondly, even small or local changes in free Zn(ii) may significantly affect protein saturation depending on its architecture, function and subcellular concentration. In our paper, we indicate the importance of interdependence of free Zn(ii) availability and protein subunit concentrations for cellular zinc signal regulation.

  7. Membrane fluidization by alcohols inhibits DesK-DesR signalling in Bacillus subtilis.

    PubMed

    Vaňousová, Kateřina; Beranová, Jana; Fišer, Radovan; Jemioła-Rzemińska, Malgorzata; Matyska Lišková, Petra; Cybulski, Larisa; Strzałka, Kazimierz; Konopásek, Ivo

    2018-03-01

    After cold shock, the Bacillus subtilis desaturase Des introduces double bonds into the fatty acids of existing membrane phospholipids. The synthesis of Des is regulated exclusively by the two-component system DesK/DesR; DesK serves as a sensor of the state of the membrane and triggers Des synthesis after a decrease in membrane fluidity. The aim of our work is to investigate the biophysical changes in the membrane that are able to affect the DesK signalling state. Using linear alcohols (ethanol, propanol, butanol, hexanol, octanol) and benzyl alcohol, we were able to suppress Des synthesis after a temperature downshift. The changes in the biophysical properties of the membrane caused by alcohol addition were followed using membrane fluorescent probes and differential scanning calorimetry. We found that the membrane fluidization induced by alcohols was reflected in an increased hydration at the lipid-water interface. This is associated with a decrease in DesK activity. The addition of alcohol mimics a temperature increase, which can be measured isothermically by fluorescence anisotropy. The effect of alcohols on the membrane periphery is in line with the concept of the mechanism by which two hydrophilic motifs located at opposite ends of the transmembrane region of DesK, which work as a molecular caliper, sense temperature-dependent variations in membrane properties. Copyright © 2017 Elsevier B.V. All rights reserved.

  8. Possible role of zinc in diminishing lead-related occupational stress-a zinc nutrition concern.

    PubMed

    Wani, Ab Latif; Ahmad, Ajaz; Shadab, G G H A; Usmani, Jawed Ahmad

    2017-03-01

    Lead and zinc are mostly present at the same occupational source and usually found as co-contaminants. Lead is known to associate with detrimental effects to humans. Zinc however is an essential nutrient and its deficiency causes debilitating effects on growth and development. Besides, it acts as core ion of important enzymes and proteins. The purpose of this study was to examine if zinc concentrations are associated with blood lead levels and if zinc may prevent lead-induced DNA damage. Blood samples were collected from 92 workers as participants occupationally exposed to lead or lead and zinc and 38 comparison participants having no history of such exposure. Lead and zinc levels were determined from blood by atomic absorption spectrophotometry and genetic damage was assessed by comet assay. Correlation was calculated by Spearman's rho. Lead concentrations were observed to increase among workers with increase in years of exposure. There was a significant difference (p < 0.001) in blood lead levels between workers and controls. In addition, significant difference (p < 0.001) in the genetic damage was observed among workers and controls. A clear effect of increased occupational exposure was visible among workers. Multiple regression analysis further reveals the positive effect of lead, while as the inverse effect of zinc on DNA damage. The results suggest that zinc may influence body lead absorption and may have a role in preventing the genetic damage caused by lead.

  9. Effects of dietary supplementation with tribasic zinc sulfate or zinc sulfate on growth performance, zinc content and expression of zinc transporters in young pigs.

    PubMed

    Deng, Bo; Zhou, Xihong; Wu, Jie; Long, Ciming; Yao, Yajun; Peng, Hongxing; Wan, Dan; Wu, Xin

    2017-10-01

    An experiment was conducted to compare the effects of zinc sulfate (ZS) and tribasic zinc sulfate (TBZ) as sources of supplemental zinc on growth performance, serum zinc (Zn) content and messenger RNA (mRNA) expression of Zn transporters (ZnT1/ZnT2/ZnT5/ZIP4/DMT1) of young growing pigs. A total of 96 Duroc × Landrace × Yorkshire pigs were randomly allotted to two treatments and were fed a basal diet supplemented with 100 mg/kg Zn from either ZS or TBZ for 28 days. Feed : gain ratio in pigs fed TBZ were lower (P < 0.05) than pigs fed ZS, and average daily weight gain tended to increase (0.05 ≤ P ≤ 0.10) in pigs fed TBZ. Compared with pigs fed ZS, pigs fed TBZ had a higher CuZn-superoxide dismutase and Zn content in serum (P < 0.05) while they had a lower Zn content in feces (P < 0.05). In addition, ZIP4 mRNA expression of zinc transporter in either duodenum or jejunum of pigs fed TBZ were higher (P < 0.05) than pigs fed ZS. These results indicate that TBZ is more effective in serum Zn accumulation and intestinal Zn absorption, and might be a potential substitute for ZS in young growing pigs. © 2017 Japanese Society of Animal Science.

  10. Analysis of cellular responses of macrophages to zinc ions and zinc oxide nanoparticles: a combined targeted and proteomic approach.

    PubMed

    Triboulet, Sarah; Aude-Garcia, Catherine; Armand, Lucie; Gerdil, Adèle; Diemer, Hélène; Proamer, Fabienne; Collin-Faure, Véronique; Habert, Aurélie; Strub, Jean-Marc; Hanau, Daniel; Herlin, Nathalie; Carrière, Marie; Van Dorsselaer, Alain; Rabilloud, Thierry

    2014-06-07

    Two different zinc oxide nanoparticles, as well as zinc ions, are used to study the cellular responses of the RAW 264 macrophage cell line. A proteomic screen is used to provide a wide view of the molecular effects of zinc, and the most prominent results are cross-validated by targeted studies. Furthermore, the alteration of important macrophage functions (e.g. phagocytosis) by zinc is also investigated. The intracellular dissolution/uptake of zinc is also studied to further characterize zinc toxicity. Zinc oxide nanoparticles dissolve readily in the cells, leading to high intracellular zinc concentrations, mostly as protein-bound zinc. The proteomic screen reveals a rather weak response in the oxidative stress response pathway, but a strong response both in the central metabolism and in the proteasomal protein degradation pathway. Targeted experiments confirm that carbohydrate catabolism and proteasome are critical determinants of sensitivity to zinc, which also induces DNA damage. Conversely, glutathione levels and phagocytosis appear unaffected at moderately toxic zinc concentrations.

  11. Recovering Zinc From Discarded Tires

    NASA Technical Reports Server (NTRS)

    Du Fresne, E. R.

    1984-01-01

    Zinc sulfate monohydrate sold at profit. Shredded tire material steeped in three sulfuric acid baths to extract zinc. Final product removed by evaporating part of solution until product crystallizes out. Recovered as zinc sulfate monohydrate and sold as fertilizer or for general use.

  12. Zinc Signal in Brain Diseases.

    PubMed

    Portbury, Stuart D; Adlard, Paul A

    2017-11-23

    The divalent cation zinc is an integral requirement for optimal cellular processes, whereby it contributes to the function of over 300 enzymes, regulates intracellular signal transduction, and contributes to efficient synaptic transmission in the central nervous system. Given the critical role of zinc in a breadth of cellular processes, its cellular distribution and local tissue level concentrations remain tightly regulated via a series of proteins, primarily including zinc transporter and zinc import proteins. A loss of function of these regulatory pathways, or dietary alterations that result in a change in zinc homeostasis in the brain, can all lead to a myriad of pathological conditions with both acute and chronic effects on function. This review aims to highlight the role of zinc signaling in the central nervous system, where it may precipitate or potentiate diverse issues such as age-related cognitive decline, depression, Alzheimer's disease or negative outcomes following brain injury.

  13. Zinc in Entamoeba invadens.

    NASA Technical Reports Server (NTRS)

    Morgan, R. S.; Sattilaro, R. F.

    1972-01-01

    Atomic absorption spectroscopy, electron microprobe analysis, and dithizone staining of trophozoites and cysts of Entamoeba invadens demonstrate that these cells have a high concentration of zinc (approximately one picogram per cell or 1% of their dry weight). In the cysts of this organism, the zinc is confined to the chromatoid bodies, which previous work has shown to contain crystals of ribosomes. The chemical state and function of this zinc are unknown.

  14. Consumption of artificially and sugar-sweetened beverages and incident type 2 diabetes in the Etude Epidemiologique aupres des femmes de la Mutuelle Generale de l'Education Nationale-European Prospective Investigation into Cancer and Nutrition cohort.

    PubMed

    Fagherazzi, Guy; Vilier, Alice; Saes Sartorelli, Daniela; Lajous, Martin; Balkau, Beverley; Clavel-Chapelon, Françoise

    2013-03-01

    It has been extensively shown, mainly in US populations, that sugar-sweetened beverages (SSBs) are associated with increased risk of type 2 diabetes (T2D), but less is known about the effects of artificially sweetened beverages (ASBs). We evaluated the association between self-reported SSB, ASB, and 100% fruit juice consumption and T2D risk over 14 y of follow-up in the French prospective Etude Epidémiologique auprès des femmes de la Mutuelle Générale de l'Education Nationale-European Prospective Investigation into Cancer and Nutrition cohort. A total of 66,118 women were followed from 1993, and 1369 incident cases of T2D were diagnosed during the follow-up. Cox regression models were used to estimate HRs and 95% CIs for T2D risk. The average consumption of sweetened beverages in consumers was 328 and 568 mL/wk for SSBs and ASBs, respectively. Compared with nonconsumers, women in the highest quartiles of SSB and ASB consumers were at increased risk of T2D with HRs (95% CIs) of 1.34 (1.05, 1.71) and 2.21 (1.56, 3.14) for women who consumed >359 and >603 mL/wk of SSBs and ASBs, respectively. Strong positive trends in T2D risk were also observed across quartiles of consumption for both types of beverage (P = 0.0088 and P < 0.0001, respectively). In sensitivity analyses, associations were partly mediated by BMI, although there was still a strong significant independent effect. No association was observed for 100% fruit juice consumption. Both SSB consumption and ASB consumption were associated with increased T2D risk. We cannot rule out that factors other than ASB consumption that we did not control for are responsible for the association with diabetes, and randomized trials are required to prove a causal link between ASB consumption and T2D.

  15. A Photoluminescence Study of the Changes Induced in the Zinc White Pigment by Formation of Zinc Complexes

    PubMed Central

    Artesani, Alessia; Gherardi, Francesca; Nevin, Austin; Valentini, Gianluca; Comelli, Daniela

    2017-01-01

    It is known that oil paintings containing zinc white are subject to rapid degradation. This is caused by the interaction between the active groups of binder and the metal ions of the pigment, which gives rise to the formation of new zinc complexes (metal soaps). Ongoing studies on zinc white paints have been limited to the chemical mechanisms that lead to the formation of zinc complexes. On the contrary, little is known of the photo-physical changes induced in the zinc oxide crystal structure following this interaction. Time-resolved photoluminescence spectroscopy has been applied to follow modifications in the luminescent zinc white pigment when mixed with binder. Significant changes in trap state photoluminescence emissions have been detected: the enhancement of a blue emission combined with a change of the decay kinetic of the well-known green emission. Complementary data from molecular analysis of paints using Fourier transform infrared spectroscopy confirms the formation of zinc carboxylates and corroborates the mechanism for zinc complexes formation. We support the hypothesis that zinc ions migrate into binder creating novel vacancies, affecting the photoluminescence intensity and lifetime properties of zinc oxide. Here, we further demonstrate the advantages of a time-resolved photoluminescence approach for studying defects in semiconductor pigments. PMID:28772700

  16. Zinc in Infection and Inflammation

    PubMed Central

    Gammoh, Nour Zahi; Rink, Lothar

    2017-01-01

    Micronutrient homeostasis is a key factor in maintaining a healthy immune system. Zinc is an essential micronutrient that is involved in the regulation of the innate and adaptive immune responses. The main cause of zinc deficiency is malnutrition. Zinc deficiency leads to cell-mediated immune dysfunctions among other manifestations. Consequently, such dysfunctions lead to a worse outcome in the response towards bacterial infection and sepsis. For instance, zinc is an essential component of the pathogen-eliminating signal transduction pathways leading to neutrophil extracellular traps (NET) formation, as well as inducing cell-mediated immunity over humoral immunity by regulating specific factors of differentiation. Additionally, zinc deficiency plays a role in inflammation, mainly elevating inflammatory response as well as damage to host tissue. Zinc is involved in the modulation of the proinflammatory response by targeting Nuclear Factor Kappa B (NF-κB), a transcription factor that is the master regulator of proinflammatory responses. It is also involved in controlling oxidative stress and regulating inflammatory cytokines. Zinc plays an intricate function during an immune response and its homeostasis is critical for sustaining proper immune function. This review will summarize the latest findings concerning the role of this micronutrient during the course of infections and inflammatory response and how the immune system modulates zinc depending on different stimuli. PMID:28629136

  17. A concentrated electrolyte for zinc hexacyanoferrate electrodes in aqueous rechargeable zinc-ion batteries

    NASA Astrophysics Data System (ADS)

    Kim, D.; Lee, C.; Jeong, S.

    2018-01-01

    In this study, a concentrated electrolyte was applied in an aqueous rechargeable zinc-ion battery system with a zinc hexacyanoferrate (ZnHCF) electrode to improve the electrochemical performance by changing the hydration number of the zinc ions. To optimize the active material, ZnHCF was synthesized using aqueous solutions of zinc nitrate with three different concentrations. The synthesized materials exhibited some differences in structure, crystallinity, and particle size, as observed by X-ray diffraction and scanning electron microscopy. Subsequently, these well-structured materials were applied in electrochemical tests. A more than two-fold improvement in the charge/discharge capacities was observed when the concentrated electrolyte was used instead of the dilute electrolyte. Additionally, the cycling performance observed in the concentrated electrolyte was superior to that in the dilute electrolyte. This improvement in the electrochemical performance may result from a decrease in the hydration number of the zinc ions in the concentrated electrolyte.

  18. New Insights into the Role of Zinc Acquisition and Zinc Tolerance in Group A Streptococcal Infection.

    PubMed

    Ong, Cheryl-Lynn Y; Berking, Olga; Walker, Mark J; McEwan, Alastair G

    2018-06-01

    Zinc plays an important role in host innate immune function. However, the innate immune system also utilizes zinc starvation ("nutritional immunity") to combat infections. Here, we investigate the role of zinc import and export in the protection of Streptococcus pyogenes (group A Streptococcus ; GAS), a Gram-positive bacterial pathogen responsible for a wide spectrum of human diseases, against challenge from host innate immune defense. In order to determine the role of GAS zinc import and export during infection, we utilized zinc import (Δ adcA Δ adcAII ) and export (Δ czcD ) deletion mutants in competition with the wild type in both in vitro and in vivo virulence models. We demonstrate that nutritional immunity is deployed extracellularly, while zinc toxicity is utilized upon phagocytosis of GAS by neutrophils. We also show that lysosomes and azurophilic granules in neutrophils contain zinc stores for use against intracellular pathogens. Copyright © 2018 American Society for Microbiology.

  19. Particulate nanocomposite from oyster (Crassostrea rivularis) hydrolysates via zinc chelation improves zinc solubility and peptide activity.

    PubMed

    Zhang, Ziran; Zhou, Feibai; Liu, Xiaoling; Zhao, Mouming

    2018-08-30

    An oyster protein hydrolysates-zinc complex (OPH-Zn) was prepared and investigated to improve zinc bioaccessibility. Zinc ions chelating with oyster protein hydrolysates (OPH) cause intramolecular and intermolecular folding and aggregation, homogeneously forming the OPH-Zn complex as nanoclusters with a Z-average at 89.28 nm (PDI: 0.16 ± 0.02). The primary sites of zinc-binding in OPH were carboxyl groups, carbonyl groups, and amino groups, and they were related to the high number of charged amino acid residues. Furthermore, formation of the OPH-Zn complex could significantly enhance zinc solubility both under specific pH conditions as well as during simulated gastrointestinal digestion, compared to the commonly used ZnSO 4 . Additionally, after digestion, either preserved or enhanced antioxidant activity of OPH was found when chelated with zinc. These results indicated that the OPH-Zn complex could be a potential functional ingredient with improved antioxidant bioactivity and zinc bioaccessibility. Copyright © 2018. Published by Elsevier Ltd.

  20. Zinc-mediated Allosteric Inhibition of Caspase-6*

    PubMed Central

    Velázquez-Delgado, Elih M.; Hardy, Jeanne A.

    2012-01-01

    Zinc and caspase-6 have independently been implicated in several neurodegenerative disorders. Depletion of zinc intracellularly leads to apoptosis by an unknown mechanism. Zinc inhibits cysteine proteases, including the apoptotic caspases, leading to the hypothesis that zinc-mediated inhibition of caspase-6 might contribute to its regulation in a neurodegenerative context. Using inductively coupled plasma optical emission spectroscopy, we observed that caspase-6 binds one zinc per monomer, under the same conditions where the zinc leads to complete loss of enzymatic activity. To understand the molecular details of zinc binding and inhibition, we performed an anomalous diffraction experiment above the zinc edge. The anomalous difference maps showed strong 5σ peaks, indicating the presence of one zinc/monomer bound at an exosite distal from the active site. Zinc was not observed bound to the active site. The zinc in the exosite was liganded by Lys-36, Glu-244, and His-287 with a water molecule serving as the fourth ligand, forming a distorted tetrahedral ligation sphere. This exosite appears to be unique to caspase-6, as the residues involved in zinc binding were not conserved across the caspase family. Our data suggest that binding of zinc at the exosite is the primary route of inhibition, potentially locking caspase-6 into the inactive helical conformation. PMID:22891250

  1. The biological inorganic chemistry of zinc ions.

    PubMed

    Krężel, Artur; Maret, Wolfgang

    2016-12-01

    The solution and complexation chemistry of zinc ions is the basis for zinc biology. In living organisms, zinc is redox-inert and has only one valence state: Zn(II). Its coordination environment in proteins is limited by oxygen, nitrogen, and sulfur donors from the side chains of a few amino acids. In an estimated 10% of all human proteins, zinc has a catalytic or structural function and remains bound during the lifetime of the protein. However, in other proteins zinc ions bind reversibly with dissociation and association rates commensurate with the requirements in regulation, transport, transfer, sensing, signalling, and storage. In contrast to the extensive knowledge about zinc proteins, the coordination chemistry of the "mobile" zinc ions in these processes, i.e. when not bound to proteins, is virtually unexplored and the mechanisms of ligand exchange are poorly understood. Knowledge of the biological inorganic chemistry of zinc ions is essential for understanding its cellular biology and for designing complexes that deliver zinc to proteins and chelating agents that remove zinc from proteins, for detecting zinc ion species by qualitative and quantitative analysis, and for proper planning and execution of experiments involving zinc ions and nanoparticles such as zinc oxide (ZnO). In most investigations, reference is made to zinc or Zn 2+ without full appreciation of how biological zinc ions are buffered and how the d-block cation Zn 2+ differs from s-block cations such as Ca 2+ with regard to significantly higher affinity for ligands, preference for the donor atoms of ligands, and coordination dynamics. Zinc needs to be tightly controlled. The interaction with low molecular weight ligands such as water and inorganic and organic anions is highly relevant to its biology but in contrast to its coordination in proteins has not been discussed in the biochemical literature. From the discussion in this article, it is becoming evident that zinc ion speciation is

  2. 21 CFR 522.2690 - Zinc gluconate.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 6 2011-04-01 2011-04-01 false Zinc gluconate. 522.2690 Section 522.2690 Food and..., FEEDS, AND RELATED PRODUCTS IMPLANTATION OR INJECTABLE DOSAGE FORM NEW ANIMAL DRUGS § 522.2690 Zinc gluconate. (a) Specifications. Each milliliter of solution contains 13.1 milligrams zinc as zinc gluconate...

  3. 21 CFR 522.2690 - Zinc gluconate.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Zinc gluconate. 522.2690 Section 522.2690 Food and..., FEEDS, AND RELATED PRODUCTS IMPLANTATION OR INJECTABLE DOSAGE FORM NEW ANIMAL DRUGS § 522.2690 Zinc gluconate. (a) Specifications. Each milliliter of solution contains 13.1 milligrams zinc as zinc gluconate...

  4. Longitudinal changes in zinc transport kinetics, metallothionein, and zinc transporter expression in a blood-brain barrier model in response to a moderately excessive zinc environment$

    PubMed Central

    Gauthier, Nicole A.; Karki, Shakun; Olley, Bryony J.; Thomas, W. Kelly

    2008-01-01

    A blood-brain barrier (BBB) model composed of porcine brain capillary endothelial cells (BCEC) was exposed to a moderately excessive zinc environment (50 µmol Zn/L) in cell culture and longitudinal measurements were made of zinc transport kinetics, ZnT-1 (SLC30A1) expression, and changes in the protein concentration of metallothionein (MT), ZnT-1, ZnT-2 (SLC30A2), and Zip1 (SLC39A1). Zinc release by cells of the BBB model was significantly increased after 12–24 h of exposure, but decreased back to control levels after 48–96 h, as indicated by transport across the BBB from both the ablumenal (brain) and lumenal (blood) directions. Expression of ZnT-1, the zinc export protein, increased 169% within 12 h, but was no longer different from controls after 24 h. Likewise, ZnT-1 protein content increased transiently after 12 h of exposure but returned to control levels by 24 h. Capacity for zinc uptake and retention increased from both the lumenal and ablumenal directions within 12–24 h of exposure and remained elevated. MT and ZnT-2 were elevated within 12 h and remained elevated throughout the study. Zip1 was unchanged by the treatment. The BBB’s response to a moderately high zinc environment was dynamic and involved multiple mechanisms. The initial response was to increase the cell’s capacity to sequester zinc with additional MT and increase zinc export with the ZnT-1 protein. But, the longer term strategy involved increasing ZnT-2 transporters, presumably to sequester zinc into intracellular vesicles as a mechanism to protect the brain and maintain brain zinc homeostasis. PMID:18061429

  5. Zinc-The key to preventing corrosion

    USGS Publications Warehouse

    Kropschot, S.J.; Doebrich, Jeff L.

    2011-01-01

    Centuries before it was identified as an element, zinc was used to make brass (an alloy of zinc and copper) and for medicinal purposes. Metallic zinc and zinc oxide were produced in India sometime between the 11th and 14th centuries and in China in the 17th century, although the discovery of pure metallic zinc is credited to the German chemist Andreas Marggraf, who isolated the element in 1746. Refined zinc metal is bluish-white when freshly cast; it is hard and brittle at most temperatures and has relatively low melting and boiling points. Zinc alloys readily with other metals and is chemically active. On exposure to air, it develops a thin gray oxide film (patina), which inhibits deeper oxidation (corrosion) of the metal. The metal's resistance to corrosion is an important characteristic in its use.

  6. Rechargeable zinc cell with alkaline electrolyte which inhibits shape change in zinc electrode

    DOEpatents

    Adler, Thomas C.; McLarnon, Frank R.; Cairns, Elton J.

    1995-01-01

    An improved rechargeable zinc cell is described comprising a zinc electrode and another electrode such as, for example, a nickel-containing electrode, and having an electrolyte containing one or more hydroxides having the formula M(OH), one or more fluorides having the formula MF, and one or more carbonates having the formula M.sub.2 CO.sub.3, where M is a metal selected from the group consisting of alkali metals. The electrolyte inhibits shape change in the zinc electrode, i.e., the zinc electrode exhibits low shape change, resulting in an improved capacity retention of the cell over an number of charge-discharge cycles, while still maintaining high discharge rate characteristics.

  7. A role for the Drosophila zinc transporter Zip88E in protecting against dietary zinc toxicity.

    PubMed

    Richards, Christopher D; Warr, Coral G; Burke, Richard

    2017-01-01

    Zinc absorption in animals is thought to be regulated in a local, cell autonomous manner with intestinal cells responding to dietary zinc content. The Drosophila zinc transporter Zip88E shows strong sequence similarity to Zips 42C.1, 42C.2 and 89B as well as mammalian Zips 1, 2 and 3, suggesting that it may act in concert with the apically-localised Drosophila zinc uptake transporters to facilitate dietary zinc absorption by importing ions into the midgut enterocytes. However, the functional characterisation of Zip88E presented here indicates that Zip88E may instead play a role in detecting and responding to zinc toxicity. Larvae homozygous for a null Zip88E allele are viable yet display heightened sensitivity to elevated levels of dietary zinc. This decreased zinc tolerance is accompanied by an overall decrease in Metallothionein B transcription throughout the larval midgut. A Zip88E reporter gene is expressed only in the salivary glands, a handful of enteroendocrine cells at the boundary between the anterior and middle midgut regions, and in two parallel strips of sensory cell projections connecting to the larval ventral ganglion. Zip88E expression solely in this restricted subset of cells is sufficient to rescue the Zip88E mutant phenotype. Together, our data suggest that Zip88E may be functioning in a small subset of cells to detect excessive zinc levels and induce a systemic response to reduce dietary zinc absorption and hence protect against toxicity.

  8. Zinc Fortification Decreases ZIP1 Gene Expression of Some Adolescent Females with Appropriate Plasma Zinc Levels

    PubMed Central

    Méndez, Rosa O.; Santiago, Alejandra; Yepiz-Plascencia, Gloria; Peregrino-Uriarte, Alma B.; de la Barca, Ana M. Calderón; García, Hugo S.

    2014-01-01

    Zinc homeostasis is achieved after intake variation by changes in the expression levels of zinc transporters. The aim of this study was to evaluate dietary intake (by 24-h recall), absorption, plasma zinc (by absorption spectrophotometry) and the expression levels (by quantitative PCR), of the transporters ZIP1 (zinc importer) and ZnT1 (zinc exporter) in peripheral white blood cells from 24 adolescent girls before and after drinking zinc-fortified milk for 27 day. Zinc intake increased (p < 0.001) from 10.5 ± 3.9 mg/day to 17.6 ± 4.4 mg/day, and its estimated absorption from 3.1 ± 1.2 to 5.3 ± 1.3 mg/day. Mean plasma zinc concentration remained unchanged (p > 0.05) near 150 µg/dL, but increased by 31 µg/dL (p < 0.05) for 6/24 adolescents (group A) and decreased by 25 µg/dL (p < 0.05) for other 6/24 adolescents (group B). Expression of ZIP1 in blood leukocytes was reduced 1.4-fold (p < 0.006) in group A, while for the expression of ZnT1 there was no difference after intervention (p = 0.39). An increase of dietary zinc after 27-days consumption of fortified-milk did not increase (p > 0.05) the plasma level of adolescent girls but for 6/24 participants from group A in spite of the formerly appropriation, which cellular zinc uptake decreased as assessed by reduction of the expression of ZIP1. PMID:24922175

  9. Regeneration of zinc chloride hydrocracking catalyst

    DOEpatents

    Zielke, Clyde W.

    1979-01-01

    Improved rate of recovery of zinc values from the solids which are carried over by the effluent vapors from the oxidative vapor phase regeneration of spent zinc chloride catalyst is achieved by treatment of the solids with both hydrogen chloride and calcium chloride to selectively and rapidly recover the zinc values as zinc chloride.

  10. Des ballons pour demain

    NASA Astrophysics Data System (ADS)

    Régipa, R.

    A partir d'une théorie sur la détermination des formes et des contraintes globales d'un ballon de révolution, ou s'en rapprochant, une nouvelle famille de ballons a été définie. Les ballons actuels, dits de ``forme naturelle'', sont calculés en général pour une tension circonférencielle nulle. Ainsi, pour une mission donnée, la tension longitudinale et la forme de l'enveloppe sont strictement imposées. Les ballons de la nouvelle génération sont globalement cylindriques et leurs pôles sont réunis par un câble axial, chargé de transmettre une partie des efforts depuis le crochet (pôle inférieur), directement au pôle supérieur. De plus, la zone latérale cylindrique est soumise à un faible champ de tensions circonférencielles. Ainsi, deux paramètres permettent de faire évoluer la distribution des tensions et la forme de l'enveloppe: - la tension du câble de liaison entre pôles (ou la longueur de ce câble) - la tension circonférencielle moyenne désirée (ou le rayon du ballon). On peut donc calculer et réaliser: - soit des ballons de forme adaptée, comme les ballons à fond plat pour le bon fonctionnement des montgolfières infrarouge (projet MIR); - soit des ballons optimisés pour une bonne répartition des contraintes et une meilleure utilisation des matériaux d'enveloppe, pour l'ensemble des programmes stratosphériques. Il s'ensuit une économie sensible des coûts de fabrication, une fiabilité accrue du fonctionnement de ces ballons et une rendement opérationnel bien supérieur, permettant entre autres, d'envisager des vols à très haute altitude en matériaux très légers.

  11. Medicago truncatula Zinc-Iron Permease6 provides zinc to rhizobia-infected nodule cells.

    PubMed

    Abreu, Isidro; Saéz, Ángela; Castro-Rodríguez, Rosario; Escudero, Viviana; Rodríguez-Haas, Benjamín; Senovilla, Marta; Larue, Camille; Grolimund, Daniel; Tejada-Jiménez, Manuel; Imperial, Juan; González-Guerrero, Manuel

    2017-11-01

    Zinc is a micronutrient required for symbiotic nitrogen fixation. It has been proposed that in model legume Medicago truncatula, zinc is delivered by the root vasculature into the nodule and released in the infection/differentiation zone. There, transporters must introduce this element into rhizobia-infected cells to metallate the apoproteins that use zinc as a cofactor. MtZIP6 (Medtr4g083570) is an M. truncatula Zinc-Iron Permease (ZIP) that is expressed only in roots and nodules, with the highest expression levels in the infection/differentiation zone. Immunolocalization studies indicate that it is located in the plasma membrane of nodule rhizobia-infected cells. Down-regulating MtZIP6 expression levels with RNAi does not result in any strong phenotype when plants are fed mineral nitrogen. However, these plants displayed severe growth defects when they depended on nitrogen fixed by their nodules, losing of 80% of their nitrogenase activity. The reduction of this activity was likely an indirect effect of zinc being retained in the infection/differentiation zone and not reaching the cytosol of rhizobia-infected cells. These data are consistent with a model in which MtZIP6 would be responsible for zinc uptake by rhizobia-infected nodule cells in the infection/differentiation zone. © 2017 John Wiley & Sons Ltd.

  12. Primary and Secondary Vestibular Connections in the Brain Stem and Cerebellum: An Axoplasmic Transport Study in the Monkey and Cat

    DTIC Science & Technology

    1983-08-25

    Edinger-Westphal nucleus in the cat, Brain Research, 141 (1978) 153-159. Lorente de No, R., Etudes sur le cerveau posterieur. Ill, Sur 1 es connexions...extra-cerebelleuses des fascicules afferents au cerveau , et sur la fontion de cet organe, Trav. Lab. Rech. Biol. Univ. Madrid, 22 (1924) 51-65

  13. Total Zinc Intake May Modify the Glucose-Raising Effect of a Zinc Transporter (SLC30A8) Variant

    PubMed Central

    Kanoni, Stavroula; Nettleton, Jennifer A.; Hivert, Marie-France; Ye, Zheng; van Rooij, Frank J.A.; Shungin, Dmitry; Sonestedt, Emily; Ngwa, Julius S.; Wojczynski, Mary K.; Lemaitre, Rozenn N.; Gustafsson, Stefan; Anderson, Jennifer S.; Tanaka, Toshiko; Hindy, George; Saylor, Georgia; Renstrom, Frida; Bennett, Amanda J.; van Duijn, Cornelia M.; Florez, Jose C.; Fox, Caroline S.; Hofman, Albert; Hoogeveen, Ron C.; Houston, Denise K.; Hu, Frank B.; Jacques, Paul F.; Johansson, Ingegerd; Lind, Lars; Liu, Yongmei; McKeown, Nicola; Ordovas, Jose; Pankow, James S.; Sijbrands, Eric J.G.; Syvänen, Ann-Christine; Uitterlinden, André G.; Yannakoulia, Mary; Zillikens, M. Carola; Wareham, Nick J.; Prokopenko, Inga; Bandinelli, Stefania; Forouhi, Nita G.; Cupples, L. Adrienne; Loos, Ruth J.; Hallmans, Goran; Dupuis, Josée; Langenberg, Claudia; Ferrucci, Luigi; Kritchevsky, Stephen B.; McCarthy, Mark I.; Ingelsson, Erik; Borecki, Ingrid B.; Witteman, Jacqueline C.M.; Orho-Melander, Marju; Siscovick, David S.; Meigs, James B.; Franks, Paul W.; Dedoussis, George V.

    2011-01-01

    OBJECTIVE Many genetic variants have been associated with glucose homeostasis and type 2 diabetes in genome-wide association studies. Zinc is an essential micronutrient that is important for β-cell function and glucose homeostasis. We tested the hypothesis that zinc intake could influence the glucose-raising effect of specific variants. RESEARCH DESIGN AND METHODS We conducted a 14-cohort meta-analysis to assess the interaction of 20 genetic variants known to be related to glycemic traits and zinc metabolism with dietary zinc intake (food sources) and a 5-cohort meta-analysis to assess the interaction with total zinc intake (food sources and supplements) on fasting glucose levels among individuals of European ancestry without diabetes. RESULTS We observed a significant association of total zinc intake with lower fasting glucose levels (β-coefficient ± SE per 1 mg/day of zinc intake: −0.0012 ± 0.0003 mmol/L, summary P value = 0.0003), while the association of dietary zinc intake was not significant. We identified a nominally significant interaction between total zinc intake and the SLC30A8 rs11558471 variant on fasting glucose levels (β-coefficient ± SE per A allele for 1 mg/day of greater total zinc intake: −0.0017 ± 0.0006 mmol/L, summary interaction P value = 0.005); this result suggests a stronger inverse association between total zinc intake and fasting glucose in individuals carrying the glucose-raising A allele compared with individuals who do not carry it. None of the other interaction tests were statistically significant. CONCLUSIONS Our results suggest that higher total zinc intake may attenuate the glucose-raising effect of the rs11558471 SLC30A8 (zinc transporter) variant. Our findings also support evidence for the association of higher total zinc intake with lower fasting glucose levels. PMID:21810599

  14. Etude des connaissances, attitudes et pratiques en matière de réintégration sociale des femmes victimes de fistule obstétricale: région de l'Extrême-nord, Cameroun

    PubMed Central

    Martin, Sanou Sobze; Adogaye, Sali Ben Béchir; Rodrigue, Mabvouna Biguioh; Maurice, Douryang; Vivaldi, Teikeu Tessa Vladimir; Amede, Saah Fopa Michael; Marie, Ovaga Eyenga Landry; Meriam, Ausseil Sandra; Colizzi, Vittorio; Gianluca, Russo

    2015-01-01

    Introduction La fistule obstétricale est un orifice entre le vagin et la vessie ou le rectum, voire les deux. Ses impacts sont des conséquences anatomo-fonctionnelles et sociales. On estime à plus de 19 000 le nombre de femmes qui souffrent de fistule obstétricale au Cameroun. Méthodes Il s'agissait d'une étude transversale descriptive conduite dans trois districts de santé de la région de l'Extrême-nord. Vingt-huit femmes victimes de fistules obstétricales, quarante-deux membres de leur entourage et vingt-quatre agents de santé ont été interviewés entre Novembre et Décembre 2013. Trois types de questionnaires ont été utilisés. Les données ont été analysées dans Epi Info version 7.1.4.0. Les moyennes et les fréquences ont été calculées avec un intervalle de confiance à 95%. Résultats 46,4% des femmes victimes de fistule obstétricales interviewées avaient subi une intervention chirurgicale réparatrice parmi lesquelles, 61,5% bénéficiaient de la réintégration. Le fonds de commerce (62,5%) était l'aide la plus reçue. Vingt-deux membres de l'entourage savaient pourquoi on fait la réintégration. Selon eux, les considérations socioculturelles (68,2%), sont la principale barrière de la réintégration. D'après les agents de santé, le suivi psychosocial (58,3%) est la principale activité de la réintégration dans les centres de prise en charge de la fistule. Conclusion La prise en charge des fistules obstétricales au Cameroun souffre de manque de réintégration sociale. Ceci expliquerait en partie la persistance de cette pathologie. Un accent devrait être mis sur l'appui matériel, financier et sur le suivi psychosocial des femmes victimes de fistule obstétricale. PMID:26113915

  15. Diethylstilbestrol (DES) and Cancer

    MedlinePlus

    ... Genetics Services Directory Cancer Prevention Overview Research Diethylstilbestrol (DES) and Cancer On This Page What is DES? ... outlined in the table below. Fertility Problems in DES Daughters ( 7 ) Fertility Complication Hazard Ratio Percent Cumulative ...

  16. Electrochemical behavior of zinc particles with silica based coatings as anode material for zinc air batteries with improved discharge capacity

    NASA Astrophysics Data System (ADS)

    Schmid, M.; Willert-Porada, M.

    2017-05-01

    Silica coatings on zinc particles as anode material for alkaline zinc air batteries are expected to reduce early formation of irreversible ZnO passivation layers during discharge by controlling zinc dissolution and precipitation of supersaturated zincates, Zn(OH)42-. Zinc particles were coated with SiO2 (thickness: 15 nm) by chemical solution deposition and with Zn2SiO4 (thickness: 20 nm) by chemical vapor deposition. These coatings formed a Si(OH)4 gel in aqueous KOH and retarded hydrogen evolution by 40%. By treatment in aqueous KOH and drying afterwards, the silica coatings were changed into ZnO-K2O·SiO2 layers. In this work, the electrochemical performance of such coated zinc particles is investigated by different electrochemical methods in order to gain a deeper understanding of the mechanisms of the coatings, which reduce zinc passivation. In particular, zinc utilization and changes in internal resistance are investigated. Moreover, methods for determination of diffusion coefficients, charge carrier numbers and activation energies for electrochemical oxidation are determined. SiO2-coated zinc particles show improved discharge capacity (CVD-coated zinc: 69% zinc utilization, CSD-coated zinc: 62% zinc utilization) as compared to as-received zinc (57% zinc utilization) at C/20 rate, by reducing supersaturation of zincates. Additionally, KOH-modified SiO2-coated zinc particles enhance rechargeability after 100% depth-of-discharge.

  17. Zinc Levels in Left Ventricular Hypertrophy.

    PubMed

    Huang, Lei; Teng, Tianming; Bian, Bo; Yao, Wei; Yu, Xuefang; Wang, Zhuoqun; Xu, Zhelong; Sun, Yuemin

    2017-03-01

    Zinc is one of the most important trace elements in the body and zinc homeostasis plays a critical role in maintaining cellular structure and function. Zinc dyshomeostasis can lead to many diseases, such as cardiovascular disease. Our aim was to investigate whether there is a relationship between zinc and left ventricular hypertrophy (LVH). A total of 519 patients was enrolled and their serum zinc levels were measured in this study. We performed analyses on the relationship between zinc levels and LVH and the four LV geometry pattern patients: normal LV geometry, concentric remodeling, eccentric LVH, and concentric LVH. We performed further linear and multiple regression analyses to confirm the relationship between zinc and left ventricular mass (LVM), left ventricular mass index (LVMI), and relative wall thickness (RWT). Our data showed that zinc levels were 710.2 ± 243.0 μg/L in the control group and were 641.9 ± 215.2 μg/L in LVH patients. We observed that zinc levels were 715 ± 243.5 μg/L, 694.2 ± 242.7 μg/L, 643.7 ± 225.0 μg/L, and 638.7 ± 197.0 μg/L in normal LV geometry, concentric remodeling, eccentric LVH, and concentric LVH patients, respectively. We further found that there was a significant inverse linear relationship between zinc and LVM (p = 0.001) and LVMI (p = 0.000) but did not show a significant relationship with RWT (p = 0.561). Multiple regression analyses confirmed that the linear relationship between zinc and LVM and LVMI remained inversely significant. The present study revealed that serum zinc levels were significantly decreased in the LVH patients, especially in the eccentric LVH and concentric LVH patients. Furthermore, zinc levels were significantly inversely correlated with LVM and LVMI.

  18. Preparation, characterization and bioactivities of Athelia rolfsii exopolysaccharide-zinc complex (AEPS-zinc).

    PubMed

    Dong, Jinman; Li, Hongmei; Min, Weihong

    2018-07-01

    A new Athelia rolfsii exopolysaccharides (AEPS) were purified by Sephacryl S-300 and S-200. The physicochemical characteristics of AEPS fractions were assayed by HPGPC and GC methods. The structures of AEPS and AEPS‑zinc complex were characterized by SEM, FTIR and NMR. Moreover, the bioactivities of complex were also evaluated by experiments in vitro and in vivo. AEPSI consisted of glucose, galacturonic acid, talose, galactose, mannose and xylose, the relative contents of them were 24.74, 19.60, 33.65, 8.77, 7.97 and 5.28%, respectively. AEPSII consisted of glucose, inositol, galacturonic acid, ribitol, gluconic acid, talose and xylose, whose relative contents were 36.06, 21.21, 12.78, 11.07, 6.58, 5.45 and 6.82%, respectively. The Mw and Mn of AEPSI were 6.1324×10 4 and 1.4218×10 4 Da, those of AEPSII were 517 and 248Da. SEM observations showed that microstructures of AEPS and AEPS‑zinc complex were obviously different both in size and shape. FTIR and NMR analysis indicated that AEPS might chelate with zinc ion through hydroxy and carboxy group. In vitro experiments showed that AEPS‑zinc complex had a good bioavailability, in vivo experiments showed that it had good effect on improving zinc deficiency and antioxidant activities, which suggested that it could be used as zinc supplementation with high antioxidant activities. Copyright © 2018 Elsevier B.V. All rights reserved.

  19. History of zinc in agriculture

    USDA-ARS?s Scientific Manuscript database

    Zinc was established as essential for green plants in 1926 and for mammals in 1934. However, over 20 years would past before the first descriptions of zinc deficiencies in farm animals appeared. In 1955, it was reported that zinc supplementation would cure a parakeratosis in swine. In 1958, it wa...

  20. Maladie des vibrations

    PubMed Central

    Shen, Shixin (Cindy); House, Ronald A.

    2017-01-01

    Résumé Objectif Permettre aux médecins de famille de comprendre l’épidémiologie, la pathogenèse, les symptômes, le diagnostic et la prise en charge de la maladie des vibrations, une maladie professionnelle importante et courante au Canada. Sources d’information Une recherche a été effectuée sur MEDLINE afin de relever les recherches et comptes rendus portant sur la maladie des vibrations. Une recherche a été effectuée sur Google dans le but d’obtenir la littérature grise qui convient au contexte canadien. D’autres références ont été tirées des articles relevés. Message principal La maladie des vibrations est une maladie professionnelle répandue touchant les travailleurs de diverses industries qui utilisent des outils vibrants. La maladie est cependant sous-diagnostiquée au Canada. Elle compte 3 éléments : vasculaire, sous la forme d’un phénomène de Raynaud secondaire; neurosensoriel; et musculosquelettique. Aux stades les plus avancés, la maladie des vibrations entraîne une invalidité importante et une piètre qualité de vie. Son diagnostic exige une anamnèse minutieuse, en particulier des antécédents professionnels, un examen physique, des analyses de laboratoire afin d’éliminer les autres diagnostics, et la recommandation en médecine du travail aux fins d’investigations plus poussées. La prise en charge consiste à réduire l’exposition aux vibrations, éviter les températures froides, abandonner le tabac et administrer des médicaments. Conclusion Pour assurer un diagnostic rapide de la maladie des vibrations et améliorer le pronostic et la qualité de vie, les médecins de famille devraient connaître cette maladie professionnelle courante, et pouvoir obtenir les détails pertinents durant l’anamnèse, recommander les patients aux cliniques de médecine du travail et débuter les demandes d’indemnisation de manière appropriée. PMID:28292812

  1. Genetic causes and gene–nutrient interactions in mammalian zinc deficiencies: acrodermatitis enteropathica and transient neonatal zinc deficiency as examples.

    PubMed

    Kasana, Shakhenabat; Din, Jamila; Maret, Wolfgang

    2015-01-01

    Discovering genetic causes of zinc deficiency has been a remarkable scientific journey. It started with the description of a rare skin disease, its treatment with various agents, the successful therapy with zinc, and the identification of mutations in a zinc transporter causing the disease. The journey continues with defining the molecular and cellular pathways that lead to the symptoms caused by zinc deficiency. Remarkably, at least two zinc transporters from separate protein families are now known to be involved in the genetics of zinc deficiency. One is ZIP4, which is involved in intestinal zinc uptake. Its mutations can cause acrodermatitis enteropathica (AE) with autosomal recessive inheritance. The other one is ZnT2, the transporter responsible for supplying human milk with zinc. Mutations in this transporter cause transient neonatal zinc deficiency (TNZD) with symptoms similar to AE but with autosomal dominant inheritance. The two diseases can be distinguished in affected infants. AE is fatal if zinc is not supplied to the infant after weaning, whereas TNZD is a genetic defect of the mother limiting the supply of zinc in the milk, and therefore the infant usually will obtain enough zinc once weaned. Although these diseases are relatively rare, the full functional consequences of the numerous mutations in ZIP4 and ZnT2 and their interactions with dietary zinc are not known. In particular, it remains unexplored whether some mutations cause milder disease phenotypes or increase the risk for other diseases if dietary zinc requirements are not met or exceeded. Thus, it is not known whether widespread zinc deficiency in human populations is based primarily on a nutritional deficiency or determined by genetic factors as well. This consideration becomes even more significant with regard to mutations in the other 22 human zinc transporters, where associations with a range of diseases, including diabetes, heart disease, and mental illnesses have been observed

  2. The structural role of the zinc ion can be dispensable in prokaryotic zinc-finger domains

    PubMed Central

    Baglivo, Ilaria; Russo, Luigi; Esposito, Sabrina; Malgieri, Gaetano; Renda, Mario; Salluzzo, Antonio; Di Blasio, Benedetto; Isernia, Carla; Fattorusso, Roberto; Pedone, Paolo V.

    2009-01-01

    The recent characterization of the prokaryotic Cys2His2 zinc-finger domain, identified in Ros protein from Agrobacterium tumefaciens, has demonstrated that, although possessing a similar zinc coordination sphere, this domain is structurally very different from its eukaryotic counterpart. A search in the databases has identified ≈300 homologues with a high sequence identity to the Ros protein, including the amino acids that form the extensive hydrophobic core in Ros. Surprisingly, the Cys2His2 zinc coordination sphere is generally poorly conserved in the Ros homologues, raising the question of whether the zinc ion is always preserved in these proteins. Here, we present a functional and structural study of a point mutant of Ros protein, Ros56–142C82D, in which the second coordinating cysteine is replaced by an aspartate, 5 previously-uncharacterized representative Ros homologues from Mesorhizobium loti, and 2 mutants of the homologues. Our results indicate that the prokaryotic zinc-finger domain, which in Ros protein tetrahedrally coordinates Zn(II) through the typical Cys2His2 coordination, in Ros homologues can either exploit a CysAspHis2 coordination sphere, previously never described in DNA binding zinc finger domains to our knowledge, or lose the metal, while still preserving the DNA-binding activity. We demonstrate that this class of prokaryotic zinc-finger domains is structurally very adaptable, and surprisingly single mutations can transform a zinc-binding domain into a nonzinc-binding domain and vice versa, without affecting the DNA-binding ability. In light of our findings an evolutionary link between the prokaryotic and eukaryotic zinc-finger domains, based on bacteria-to-eukaryota horizontal gene transfer, is discussed. PMID:19369210

  3. Improved colorimetric determination of serum zinc.

    PubMed

    Johnson, D J; Djuh, Y Y; Bruton, J; Williams, H L

    1977-07-01

    We show how zinc may easily be quantified in serum by first using an optimum concentration of guanidine hydrochloride to cause release of zinc from proteins, followed by complexation of released metals with cyanide. The cyanide complex of zinc is preferentially demasked with chloral hydrate, followed by a colorimetric reaction between zinc and 4-(2-pyridylazo)resorcinol. This is a sensitive water-soluble ligand; its complex with zinc has an absorption maximum at 497 nm. Values found by this technique compare favorably with those obtained by atomic absorption spectroscopy.

  4. Etat des lieux des soins de premier recours des malades mentaux à Antananarivo : étude rétrospective

    PubMed Central

    Bakohariliva, Hasina Andrianarivony; Rafehivola, Imisanavalona Hanitrinihaja; Raobelle, Evah Norotiana; Raharivelo, Adeline; Rajaonarison, Bertille Hortense

    2018-01-01

    Résumé Religion et guérisseurs traditionnels occupent encore une place prépondérante dans la prise en charge des maladies mentales à Madagascar. Ainsi, nous nous sommes fixés comme objectif d'établir un état des lieux sur les soins de premier recours des malades mentaux. Nous avons mené une étude rétrospective descriptive s'étalant sur une période de 16 mois allant de janvier 2014 en avril 2015 au sein du service de psychiatrie du CHU de Befelatanana à Antananarivo. La prévalence des psychoses était de 25%. Le genre féminin (53%), l'ethnie merina (77%), les étudiants (45%), le niveau d'étude secondaire (40%), les célibataires (72%), la religion protestante (45%), ainsi que le niveau socio-économique moyen (57,5%) étaient prédominants. Dans les paramètres cliniques, le mode de début brutal (52%), le premier recours à la religion (40%), la présence d'antécédents des cas similaire (90%), étaient majoritaires. La schizophrénie était la pathologie la plus rencontrée dans la moitié des cas. Le délai d'amélioration en cas de traitement religieux et traditionnels était dans la moitié des cas de plus de 10 jours d'hospitalisation. Les patients ayant reçu une prise en charge psychiatrique en premier recours, étaient améliorés dans 75 % cas en moins de 10jours. Le retard du recours aux soins psychiatriques est une réalité à Madagascar qui aggrave le pronostic des psychoses. PMID:29632623

  5. Photovoltaic cells employing zinc phosphide

    DOEpatents

    Barnett, Allen M.; Catalano, Anthony W.; Dalal, Vikram L.; Masi, James V.; Meakin, John D.; Hall, Robert B.

    1984-01-01

    A photovoltaic cell having a zinc phosphide absorber. The zinc phosphide can be a single or multiple crystal slice or a thin polycrystalline film. The cell can be a Schottky barrier, heterojunction or homojunction device. Methods for synthesizing and crystallizing zinc phosphide are disclosed as well as a method for forming thin films.

  6. Modeling the temporal variability of zinc concentrations in zinc roof runoff-experimental study and uncertainty analysis.

    PubMed

    Sage, Jérémie; El Oreibi, Elissar; Saad, Mohamed; Gromaire, Marie-Christine

    2016-08-01

    This study investigates the temporal variability of zinc concentrations from zinc roof runoff. The influence of rainfall characteristics and dry period duration is evaluated by combining laboratory experiment on small zinc sheets and in situ measurements under real weather conditions from a 1.6-m(2) zinc panel. A reformulation of a commonly used conceptual runoff quality model is introduced and its ability to simulate the evolution of zinc concentrations is evaluated. A systematic and sharp decrease from initially high to relatively low and stable zinc concentrations after 0.5 to 2 mm of rainfall is observed for both experiments, suggesting that highly soluble corrosion products are removed at early stages of runoff. A moderate dependence between antecedent dry period duration and the magnitude of zinc concentrations at the beginning of a rain event is evidenced. Contrariwise, results indicate that concentrations are not significantly influenced by rainfall intensities. Simulated rainfall experiment nonetheless suggests that a slight effect of rainfall intensities may be expected after the initial decrease of concentrations. Finally, this study shows that relatively simple conceptual runoff quality models may be adopted to simulate the variability of zinc concentrations during a rain event and from a rain event to another.

  7. Short-Term Subclinical Zinc Deficiency in Weaned Piglets Affects Cardiac Redox Metabolism and Zinc Concentration.

    PubMed

    Brugger, Daniel; Windisch, Wilhelm M

    2017-04-01

    Background: Subclinical zinc deficiency (SZD) represents the common zinc malnutrition phenotype. However, its association with oxidative stress is not well understood. The heart muscle may be a promising target for studying early changes in redox metabolism. Objective: We investigated the effects of short-term SZD on cardiac redox metabolism in weaned piglets. Methods: Forty-eight weaned German Large White × Landrace × Piétrain piglets (50% castrated males and 50% females; body weight of 8.5 kg) were fed diets with different zinc concentrations for 8 d. Measurements included cardiac parameters of antioxidative capacity, stress-associated gene expression, and tissue zinc status. Analyses comprised (linear, broken-line) regression models and Pearson correlation coefficients. Results: Glutathione and α-tocopherol concentrations as well as catalase, glutathione reductase, B-cell lymphoma 2-associated X protein, and caspase 9 gene expression plateaued in response to reduction in dietary zinc from 88.0 to 57.6, 36.0, 36.5, 41.3, 55.3, and 33.8 mg/kg, respectively ( P < 0.0001). Further reduction in dietary zinc promoted a linear decrease of glutathione and α-tocopherol (30 and 0.6 nmol/mg dietary Zn, respectively; P < 0.05) and a linear increase of gene expression [0.02, 0.01, 0.003, and 0.02 Log 10 (2 -ΔΔCt )/mg dietary Zn, respectively; P < 0.05)]. Tissue zinc declined linearly with reduction in dietary zinc (0.21 mg tissue Zn/mg dietary Zn; P = 0.004) from 88.0 to 42.7 mg/kg ( P < 0.0001), below which it linearly increased inversely to further reduction in dietary zinc (0.57 mg tissue Zn/mg dietary Zn; P = 0.006). H 2 O 2 -detoxification activity and metallothionein 1A gene expression decreased linearly with reduction in dietary zinc from 88.0 to 28.1 mg/kg [0.02 mU and 0.008 Log 10 (2 -ΔΔCt )/mg dietary Zn, respectively; P < 0.05]. Fas cell-surface death receptor, etoposide-induced 2.4 and cyclin-dependent kinase inhibitor 1A gene expression correlated

  8. Zinc titanate sorbents

    DOEpatents

    Gupta, R.P.; Gangwal, S.K.; Jain, S.C.

    1998-02-03

    The present invention provides a zinc titanate sorbent material useful in desulfurization applications. The zinc titanate material is in the form of generally spherical particles of substantially uniform chemical distribution. The sorbent material is capable of absorbing sulfur compounds from a gaseous feed in an amount of at least about 15 weight percent based on the weight of the sorbent. The sorbent material is prepared by a process including: (a) forming a zinc oxide/titanium dioxide dry blend, (b) preparing a substantially uniform aqueous slurry comprising the zinc oxide/titanium dioxide dry blend, organic binder, and at least about 1 weight percent inorganic binder based on the solids weight of the slurry, (c) spray drying the slurry to produce substantially spherical particles, and (d) calcining the particles at a temperature of between about 750 to about 950 C. The dry blend is formed by mixing between about 0.5 to about 2 parts zinc oxide having a median particle size of less than about 0.5 microns, and about 1 part titanium dioxide having a median particle size of less than about 1 micron. The slurry contains substantially no free silica and may be prepared by the process including (1) preparing an aqueous solution of organic binder, (2) adding the dry blend to the aqueous solution of organic binder, and (3) adding the inorganic binder to the solution of organic binder, and blend. Additional reagents, such as a surfactant, may also be incorporated into the sorbent material. The present invention also provides a process for desulfurizing a gaseous stream. The process includes passing a gaseous stream through a reactor containing an attrition resistant zinc titanate sorbent material of the present invention.

  9. Zinc titanate sorbents

    DOEpatents

    Gupta, Raghubir P.; Gangwal, Santosh K.; Jain, Suresh C.

    1998-01-01

    The present invention provides a zinc titanate sorbent material useful in desulfurization applications. The zinc titanate material is in the form of generally spherical particles of substantially uniform chemical distribution. The sorbent material is capable of absorbing sulfur compounds from a gaseous feed in an amount of at least about 15 weight percent based on the weight of the sorbent. The sorbent material is prepared by a process including: (a) forming a zinc oxide/titanium dioxide dry blend, (b) preparing a substantially uniform aqueous slurry comprising the zinc oxide/titanium dioxide dry blend, organic binder, and at least about 1 weight percent inorganic binder based on the solids weight of the slurry, (c) spray drying the slurry to produce substantially spherical particles, and (d) calcining the particles at a temperature of between about 750.degree. C. to about 950.degree. C. The dry blend is formed by mixing between about 0.5 to about 2 parts zinc oxide having a median particle size of less than about 0.5 .mu., and about 1 part titanium dioxide having a median particle size of less than about 1 .mu.. The slurry contains substantially no free silica and may be prepared by the process including (1) preparing an aqueous solution of organic binder, (2) adding the dry blend to the aqueous solution of organic binder, and (3) adding the inorganic binder to the solution of organic binder, and blend. Additional reagents, such as a surfactant, may also be incorporated into the sorbent material. The present invention also provides a process for desulfurizing a gaseous stream. The process includes passing a gaseous stream through a reactor containing an attrition resistant zinc titanate sorbent material of the present invention.

  10. Zinc in innate and adaptive tumor immunity

    PubMed Central

    2010-01-01

    Zinc is important. It is the second most abundant trace metal with 2-4 grams in humans. It is an essential trace element, critical for cell growth, development and differentiation, DNA synthesis, RNA transcription, cell division, and cell activation. Zinc deficiency has adverse consequences during embryogenesis and early childhood development, particularly on immune functioning. It is essential in members of all enzyme classes, including over 300 signaling molecules and transcription factors. Free zinc in immune and tumor cells is regulated by 14 distinct zinc importers (ZIP) and transporters (ZNT1-8). Zinc depletion induces cell death via apoptosis (or necrosis if apoptotic pathways are blocked) while sufficient zinc levels allows maintenance of autophagy. Cancer cells have upregulated zinc importers, and frequently increased zinc levels, which allow them to survive. Based on this novel synthesis, approaches which locally regulate zinc levels to promote survival of immune cells and/or induce tumor apoptosis are in order. PMID:21087493

  11. Effects of Different Zinc Species on Cellar Zinc Distribution, Cell Cycle, Apoptosis and Viability in MDAMB231 Cells.

    PubMed

    Wang, Yan-hong; Zhao, Wen-jie; Zheng, Wei-juan; Mao, Li; Lian, Hong-zhen; Hu, Xin; Hua, Zi-chun

    2016-03-01

    Intracellular metal elements exist in mammalian cells with the concentration range from picomoles per litre to micromoles per litre and play a considerable role in various biological procedures. Element provided by different species can influence the availability and distribution of the element in a cell and could lead to different biological effects on the cell's growth and function. Zinc as an abundant and widely distributed essential trace element, is involved in numerous and relevant physiological functions. Zinc homeostasis in cells, which is regulated by metallothioneins, zinc transporter/SLC30A, Zrt-/Irt-like proteins/SLC39A and metal-response element-binding transcription factor-1 (MTF-1), is crucial for normal cellular functioning. In this study, we investigated the influences of different zinc species, zinc sulphate, zinc gluconate and bacitracin zinc, which represented inorganic, organic and biological zinc species, respectively, on cell cycle, viability and apoptosis in MDAMB231 cells. It was found that the responses of cell cycle, apoptosis and death to different zinc species in MDAMB231 cells are different. Western blot analysis of the expression of several key proteins in regulating zinc-related transcription, cell cycle, apoptosis, including MTF-1, cyclin B1, cyclin D1, caspase-8 and caspase-9 in treated cells further confirmed the observed results on cell level.

  12. Status of zinc injection in PWRs

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Bergmann, C.A.

    1995-03-01

    Based on laboratory and other studies, it was concluded that zinc addition in a PWR primary coolant should result in reduced Alloy 600 PWSCC and general corrosion rates of the materials of construction. Because of these positive results, a Westinghouse Owner`s Subgroup, EPRI, and Westinghouse provided funds to continue the development and application of zinc in an operating plant. As part of the program, Southern Operating Nuclear Company agreed to operate the Farley 2 plant with zinc addition as a demonstration test of the effectiveness of zinc. Since zinc is incorporated in the corrosion oxide film on the primary systemmore » surfaces and Farley 2 is a mature plant, it was estimated that about 10 kgs of zinc would be needed to condition the plant before an equilibrium value in the coolant would be reached. The engineered aspects of a Zinc Addition and Monitoring System (ZAMS) considered such items as the constitutents, location, sizing and water supply of the ZAMS. Baseline data such as the PWSCC history of the Alloy 600 steam generator tubing, fuel oxide thickness, fuel crud deposits, radiation levels, and RCP seal leak-off rates were obtained before zinc addition is initiated. This presentation summarizes some of the work performed under the program, and the status of zinc injection in the Farley 2 plant.« less

  13. Effects of cadmium and zinc on solar-simulated light-irradiated cells: potential role of zinc-metallothionein in zinc-induced genoprotection.

    PubMed

    Jourdan, Eric; Emonet-Piccardi, Nathalie; Didier, Christine; Beani, Jean-Claude; Favier, Alain; Richard, Marie-Jeanne

    2002-09-15

    Zinc is an essential oligoelement for cell growth and cell survival and has been demonstrated to protect cells from oxidative stress induced by UVA or from genotoxic stress due to UVB. In a recent work we demonstrated that the antioxidant role of zinc could be related to its ability to induce metallothioneins (MTs). In this study we identified the mechanism of zinc protection against solar-simulated light (SSL) injury. Cultured human keratinocytes (HaCaT) were used to examine MTs expression and localization in response to solar-simulated radiation. We found translocation to the nucleus, with overexpression of MTs in irradiated cells, a novel observation. The genoprotective effect of zinc was dependent on time and protein synthesis. DNA damage was significantly decreased after 48 h of ZnCl(2) (100 microM) treatment and is inhibited by actinomycin D. ZnCl(2) treatment (100 microM) led to an intense induction, redistribution, and accumulation of MT in the nucleus of irradiated cells. MT expression correlated with the time period of ZnCl(2) treatment. CdCl(2), a potent MT inducer, did not show any genoprotection, although the MTs were expressed in the nucleus. Overall our findings demonstrate that MTs could be a good candidate for explaining the genoprotection mediated by zinc on irradiated cells.

  14. Litigation involving DES.

    PubMed

    Rheingold, P D

    1976-01-01

    Focus is on the diethylstilbestrol (DES) litigation which has resulted from the 1971 discovery that this synthetic estrogen can cause cancer in the daughters of women who used the drug during pregnancy in an effort to prevent threatened abortion. Possibly 100 suits are pending at this time in which DES daughters claim injuries. In most of these vaginal or cervical cancer has appeared -- with or without a hysterectomy having been performed. Several women died from cancer. The fact that the use of DES occurred many years ago is the legal hurdle most troublesome to lawyers. The average women coming to a lawyer's office today has a mother who used some form of DES, perhaps in 1955. Few drugstores have records today of the prescriptions which they filled 20 years ago. It has been estimated that over the 1950-1970 period more than 200 different companies manufactured or "tabletized" under their own name DES plus a variety of similar synthetic estrogens promoted for the prevention of threatened abortion. A further hurdle caused by the passage of time is that even the records of the physicians are frequently lost. A final problem created by the age of the cases is statute of limitations. If the actual manufacturer of the DES cannot be identified, this is generally the end of the lawyer's interest in the case. The chance of the plaintiff winning may be increased if the action against all the manufacturers is a class action. Most of the pending DES suits are against the manufacturer and not against the doctor. Thus far no DES case has been tried to completion. Several have been settled by the manufacturers on the eve of the trial, generally for less than the full sum that a cancer victim would expect to receive.

  15. Systematic review of zinc fortification trials.

    PubMed

    Das, Jai K; Kumar, Rohail; Salam, Rehana A; Bhutta, Zulfiqar A

    2013-01-01

    Zinc is one of the essential trace elements required by the human body as it is present in more than a hundred specific enzymes and serves as an important structural ion in transcription factors. Around one third of the world population lives in countries with a high prevalence of zinc deficiency. Food fortification with zinc seems to be an attractive public health strategy and a number of programs have been initiated, especially in developing countries. We conducted a systematic review to assess the efficacy of zinc fortification. A total of 11 studies with 771 participants were included in our analysis. Zinc fortification was associated with significant improvements in plasma zinc concentrations [standard mean difference (SMD) 1.28, 95% CI 0.56, 2.01] which is a functional indicator of zinc status. Significant improvement was observed for height velocity (SMD 0.52, 95% CI 0.01, 1.04); however, this finding was weak and based on a restricted analysis. Further subgroup analysis showed significant improvement in height velocity among very-low-birth-weight infants (SMD 0.70, 95% CI 0.02, 1.37), while for healthy newborns, the impact was insignificant. Zinc fortification had insignificant impacts on serum alkaline levels, serum copper levels, hemoglobin and weight gain. Although the findings highlight that zinc fortification is associated with an increased serum concentration of the micronutrient, overall evidence of the effectiveness of this approach is limited. Data on pregnant and lactating women is scarce. Large-scale fortification programs with robust impact assessment should be initiated to cover larger populations in all age groups. Mass fortification of zinc may be a cost-effective strategy to overcome zinc deficiency. Copyright © 2013 S. Karger AG, Basel.

  16. Médecine des voyages

    PubMed Central

    Aw, Brian; Boraston, Suni; Botten, David; Cherniwchan, Darin; Fazal, Hyder; Kelton, Timothy; Libman, Michael; Saldanha, Colin; Scappatura, Philip; Stowe, Brian

    2014-01-01

    Résumé Objectif Définir la pratique de la médecine des voyages, présenter les éléments fondamentaux d’une consultation complète préalable aux voyages à des voyageurs internationaux et aider à identifier les patients qu’il vaudrait mieux envoyer en consultation auprès de professionnels de la médecine des voyages. Sources des données Les lignes directrices et les recommandations sur la médecine des voyages et les maladies liées aux voyages publiées par les autorités sanitaires nationales et internationales ont fait l’objet d’un examen. Une recension des ouvrages connexes dans MEDLINE et EMBASE a aussi été effectuée. Message principal La médecine des voyages est une spécialité très dynamique qui se concentre sur les soins préventifs avant un voyage. Une évaluation exhaustive du risque pour chaque voyageur est essentielle pour mesurer avec exactitude les risques particuliers au voyageur, à son itinéraire et à sa destination et pour offrir des conseils sur les interventions les plus appropriées en gestion du risque afin de promouvoir la santé et prévenir les problèmes médicaux indésirables durant le voyage. Des vaccins peuvent aussi être nécessaires et doivent être personnalisés en fonction des antécédents d’immunisation du voyageur, de son itinéraire et du temps qu’il reste avant son départ. Conclusion La santé et la sécurité d’un voyageur dépendent du degré d’expertise du médecin qui offre le counseling préalable à son voyage et les vaccins, au besoin. On recommande à ceux qui donnent des conseils aux voyageurs d’être conscients de l’ampleur de cette responsabilité et de demander si possible une consultation auprès de professionnels de la médecine des voyages pour tous les voyageurs à risque élevé.

  17. Centenary Birth Anniversary of E. W. Beth (1908-1964)

    ERIC Educational Resources Information Center

    Bagni, Giorgio T.

    2008-01-01

    Evert Willem Beth (1908-1964) was a Dutch logician, mathematician and philosopher, whose work mainly concerned the foundations of mathematics. Beth was among the founders of the Commission Internationale pour l'Etude et l'Amelioration de l'Enseignement des Mathematiques and was a member of the Central Committee of the International Commission on…

  18. The Relationship between Zinc Intake and Serum/Plasma Zinc Concentration in Children: A Systematic Review and Dose-Response Meta-Analysis

    PubMed Central

    Moran, Victoria Hall; Stammers, Anna-Louise; Medina, Marisol Warthon; Patel, Sujata; Dykes, Fiona; Souverein, Olga W.; Dullemeijer, Carla; Pérez-Rodrigo, Carmen; Serra-Majem, Lluis; Nissensohn, Mariela; Lowe, Nicola M.

    2012-01-01

    Recommendations for zinc intake during childhood vary widely across Europe. The EURRECA project attempts to consolidate the basis for the definition of micronutrient requirements, taking into account relationships among intake, status and health outcomes, in order to harmonise these recommendations. Data on zinc intake and biomarkers of zinc status reported in randomised controlled trials (RCTs) can provide estimates of dose-response relationships which may be used for underpinning zinc reference values. This systematic review included all RCTs of apparently healthy children aged 1–17 years published by February 2010 which provided data on zinc intake and biomarkers of zinc status. An intake-status regression coefficient () was calculated for each individual study and calculated the overall pooled and SE () using random effects meta-analysis on a double log scale. The pooled dose-response relationship between zinc intake and zinc status indicated that a doubling of the zinc intake increased the serum/plasma zinc status by 9%. This evidence can be utilised, together with currently used balance studies and repletion/depletion studies, when setting zinc recommendations as a basis for nutrition policies. PMID:23016120

  19. Associations between intestinal mucosal function and changes in plasma zinc concentration following zinc supplementation1

    PubMed Central

    Wessells, K. Ryan; Hess, Sonja Y.; Rouamba, Noel; Ouédraogo, Zinewendé P.; Kellogg, Mark; Goto, Rie; Duggan, Christopher; Ouédraogo, Jean-Bosco; Brown, Kenneth H.

    2015-01-01

    Objectives Subclinical environmental enteropathy is associated with malabsorption of fats, carbohydrates, and vitamins A, B12 and folate; however, little information is available on mineral absorption. We therefore investigated the relationship between intestinal mucosal function (measured by the lactulose:mannitol permeability test and plasma citrulline concentration), and zinc absorption, as estimated by the change in plasma zinc concentration (PZC) following short-term zinc or placebo supplementation. Methods We conducted a randomized, partially-masked, placebo-controlled trial among 282 apparently healthy children 6–23 mo of age in Burkina Faso. After completing baseline intestinal function tests, participants received either 5 mg zinc, as zinc sulfate, or placebo, daily for 21 d. Results At baseline, mean ± SD PZC was 62.9 ± 11.9 µg/dL; median (IQR) urinary lactulose:mannitol (L:M) recovery ratio and plasma citrulline concentration were 0.04 (0.03 – 0.07) and 11.4 (9.0 – 15.6) µmol/L, respectively. Change in PZC was significantly greater in the zinc supplemented versus placebo group (15.6 ± 13.3 µg/dL vs. 0.02 ± 10.9 µg/dL; P < 0.0001), and was negatively associated with initial urinary L:M recovery ratio (−1.1 µg/dL per 50% increase in urinary L:M recovery ratio; P = 0.014); this latter relationship did not differ between supplementation groups (P = 0.26). Baseline plasma citrulline concentration was not associated with change in PZC. Conclusions Although altered intestinal permeability may reduce dietary zinc absorption, it likely does not undermine the efficacy of zinc supplementation, given the large increases in PZC following short-term zinc supplementation observed in this study, even among those with increased urinary L:M recovery ratios. PMID:23689263

  20. A moderate increase in dietary zinc reduces DNA strand breaks in leukocytes and alters plasma proteins without changing plasma zinc concentrations123

    PubMed Central

    Zyba, Sarah J; Killilea, David W; Holland, Tai C; Kim, Elijah; Moy, Adrian; Sutherland, Barbara; Shigenaga, Mark K

    2017-01-01

    Background: Food fortification has been recommended to improve a population’s micronutrient status. Biofortification techniques modestly elevate the zinc content of cereals, but few studies have reported a positive impact on functional indicators of zinc status. Objective: We determined the impact of a modest increase in dietary zinc that was similar to that provided by biofortification programs on whole-body and cellular indicators of zinc status. Design: Eighteen men participated in a 6-wk controlled consumption study of a low-zinc, rice-based diet. The diet contained 6 mg Zn/d for 2 wk and was followed by 10 mg Zn/d for 4 wk. To reduce zinc absorption, phytate was added to the diet during the initial period. Indicators of zinc homeostasis, including total absorbed zinc (TAZ), the exchangeable zinc pool (EZP), plasma and cellular zinc concentrations, zinc transporter gene expression, and other metabolic indicators (i.e., DNA damage, inflammation, and oxidative stress), were measured before and after each dietary-zinc period. Results: TAZ increased with increased dietary zinc, but plasma zinc concentrations and EZP size were unchanged. Erythrocyte and leukocyte zinc concentrations and zinc transporter expressions were not altered. However, leukocyte DNA strand breaks decreased with increased dietary zinc, and the level of proteins involved in DNA repair and antioxidant and immune functions were restored after the dietary-zinc increase. Conclusions: A moderate 4-mg/d increase in dietary zinc, similar to that which would be expected from zinc-biofortified crops, improves zinc absorption but does not alter plasma zinc. The repair of DNA strand breaks improves, as do serum protein concentrations that are associated with the DNA repair process. This trial was registered at clinicaltrials.gov as NCT02861352. PMID:28003206

  1. Zinc phosphate conversion coatings

    DOEpatents

    Sugama, Toshifumi

    1997-01-01

    Zinc phosphate conversion coatings for producing metals which exhibit enhanced corrosion prevention characteristics are prepared by the addition of a transition-metal-compound promoter comprising a manganese, iron, cobalt, nickel, or copper compound and an electrolyte such as polyacrylic acid, polymethacrylic acid, polyitaconic acid and poly-L-glutamic acid to a phosphating solution. These coatings are further improved by the incorporation of Fe ions. Thermal treatment of zinc phosphate coatings to generate .alpha.-phase anhydrous zinc phosphate improves the corrosion prevention qualities of the resulting coated metal.

  2. Ferritin: a zinc detoxicant and a zinc ion donor.

    PubMed Central

    Price, D; Joshi, J G

    1982-01-01

    Rats were injected with 1 mg of Zn2+ as zinc sulfate or 2 mg of Cd2+ as cadmium sulfate per kg of body weight on a daily basis. After seven injections, ferritin and metallothionein were isolated from the livers of the rats. Significant amounts of zinc were associated with ferritin. Incubation of such ferritin with apoenzymes of calf intestinal alkaline phosphatase, yeast phosphoglucomutase, and yeast aldolase restored their enzymic activity. The amount of zinc injected was insufficient to stimulate significant synthesis of metallothionein, but similar experiments with injection of cadmium did stimulate the synthesis of metallothionein. The amount of Zn2+ in ferritin of Cd-injected rats was greater than that in ferritin in Zn-injected rats, which was greater than that in ferritin of normal rats. Thus at comparable protein concentration ferritin from Cd-injected rats was a better Zn2+ donor than was ferritin from Zn-injected or normal animals. Ferritin is a normal constituent of several tissues, whereas metallothionein is synthesized under metabolic stress. Thus ferritin may function as a "metal storage and transferring agent" for iron and for zinc. It is suggested that ferritin probably serves as the initial chelator for Zn2+ and perhaps other metal ions as well and that under very high toxic levels of metal ions the synthesis of metallothionein is initiated as the second line of defense. PMID:6212927

  3. Zinc phosphate conversion coatings

    DOEpatents

    Sugama, T.

    1997-02-18

    Zinc phosphate conversion coatings for producing metals which exhibit enhanced corrosion prevention characteristics are prepared by the addition of a transition-metal-compound promoter comprising a manganese, iron, cobalt, nickel, or copper compound and an electrolyte such as polyacrylic acid, polymethacrylic acid, polyitaconic acid and poly-L-glutamic acid to a phosphating solution. These coatings are further improved by the incorporation of Fe ions. Thermal treatment of zinc phosphate coatings to generate {alpha}-phase anhydrous zinc phosphate improves the corrosion prevention qualities of the resulting coated metal. 33 figs.

  4. Recovery of zinc and manganese from alkaline and zinc-carbon spent batteries

    NASA Astrophysics Data System (ADS)

    De Michelis, I.; Ferella, F.; Karakaya, E.; Beolchini, F.; Vegliò, F.

    This paper concerns the recovery of zinc and manganese from alkaline and zinc-carbon spent batteries. The metals were dissolved by a reductive-acid leaching with sulphuric acid in the presence of oxalic acid as reductant. Leaching tests were realised according to a full factorial design, then simple regression equations for Mn, Zn and Fe extraction were determined from the experimental data as a function of pulp density, sulphuric acid concentration, temperature and oxalic acid concentration. The main effects and interactions were investigated by the analysis of variance (ANOVA). This analysis evidenced the best operating conditions of the reductive acid leaching: 70% of manganese and 100% of zinc were extracted after 5 h, at 80 °C with 20% of pulp density, 1.8 M sulphuric acid concentration and 59.4 g L -1 of oxalic acid. Both manganese and zinc extraction yields higher than 96% were obtained by using two sequential leaching steps.

  5. Zinc oxide varistors and/or resistors

    DOEpatents

    Arnold, Jr., Wesley D.; Bond, Walter D.; Lauf, Robert J.

    1993-01-01

    Varistors and/or resistors that includes doped zinc oxide gel microspheres. The doped zinc oxide gel microspheres preferably have from about 60 to about 95% by weight zinc oxide and from about 5 to about 40% by weight dopants based on the weight of the zinc oxide. The dopants are a plurality of dopants selected from silver salts, boron oxide, silicon oxide and hydrons oxides of aluminum, bismuth, cobalt, chromium, manganese, nickel, and antimony.

  6. Low-Resistivity Zinc Selenide for Heterojunctions

    NASA Technical Reports Server (NTRS)

    Stirn, R. J.

    1986-01-01

    Magnetron reactive sputtering enables doping of this semiconductor. Proposed method of reactive sputtering combined with doping shows potential for yielding low-resistivity zinc selenide films. Zinc selenide attractive material for forming heterojunctions with other semiconductor compounds as zinc phosphide, cadmium telluride, and gallium arsenide. Semiconductor junctions promising for future optoelectronic devices, including solar cells and electroluminescent displays. Resistivities of zinc selenide layers deposited by evaporation or chemical vapor deposition too high to form practical heterojunctions.

  7. Effects of serum zinc level on tinnitus.

    PubMed

    Berkiten, Güler; Kumral, Tolgar Lütfi; Yıldırım, Güven; Salturk, Ziya; Uyar, Yavuz; Atar, Yavuz

    2015-01-01

    The aim of this study was to assess zinc levels in tinnitus patients, and to evaluate the effects of zinc deficiency on tinnitus and hearing loss. One-hundred patients, who presented to an outpatient clinic with tinnitus between June 2009 and 2014, were included in the study. Patients were divided into three groups according to age: Group I (patients between 18 and 30years of age); Group II (patients between 31 and 60years of age); and Group III (patients between 61 and 78years of age). Following a complete ear, nose and throat examination, serum zinc levels were measured and the severity of tinnitus was quantified using the Tinnitus Severity Index Questionnaire (TSIQ). Patients were subsequently asked to provide a subjective judgment regarding the loudness of their tinnitus. The hearing status of patients was evaluated by audiometry and high-frequency audiometry. An average hearing sensitivity was calculated as the mean value of hearing thresholds between 250 and 20,000Hz. Serum zinc levels between 70 and 120μg/dl were considered normal. The severity and loudness of tinnitus, and the hearing thresholds of the normal zinc level and zinc-deficient groups, were compared. Twelve of 100 (12%) patients exhibited low zinc levels. The mean age of the zinc-deficient group was 65.41±12.77years. Serum zinc levels were significantly lower in group III (p<0.01). The severity and loudness of tinnitus were greater in zinc-deficient patients (p=0.011 and p=0.015, respectively). Moreover, the mean thresholds of air conduction were significantly higher in zinc-deficient patients (p=0.000). We observed that zinc levels decrease as age increases. In addition, there was a significant correlation between zinc level and the severity and loudness of tinnitus. Zinc deficiency was also associated with impairments in hearing thresholds. Copyright © 2015 Elsevier Inc. All rights reserved.

  8. Zinc Status of Vegetarians during Pregnancy: A Systematic Review of Observational Studies and Meta-Analysis of Zinc Intake.

    PubMed

    Foster, Meika; Herulah, Ursula Nirmala; Prasad, Ashlini; Petocz, Peter; Samman, Samir

    2015-06-05

    Pregnant women are vulnerable to a low zinc status due to the additional zinc demands associated with pregnancy and foetal development. The present systematic review explores the relationship between habitual vegetarian diets and dietary zinc intake/status during pregnancy. The association between vegetarian diets and functional pregnancy outcome also is considered. A literature search was conducted of MEDLINE; PubMed; Embase; the Cochrane Library; Web of Science; and Scopus electronic databases up to September 2014. Six English-language observational studies qualified for inclusion in the systematic review. A meta-analysis was conducted that compared the dietary zinc intake of pregnant vegetarian and non-vegetarian (NV) groups; the zinc intake of vegetarians was found to be lower than that of NV (-1.38 ± 0.35 mg/day; p < 0.001); and the exclusion of low meat eaters from the analysis revealed a greater difference (-1.53 ± 0.44 mg/day; p = 0.001). Neither vegetarian nor NV groups met the recommended dietary allowance (RDA) for zinc. In a qualitative synthesis; no differences were found between groups in serum/plasma zinc or in functional outcomes associated with pregnancy. In conclusion; pregnant vegetarian women have lower zinc intakes than NV control populations and both groups consume lower than recommended amounts. Further information is needed to determine whether physiologic adaptations in zinc metabolism are sufficient to meet maternal and foetal requirements during pregnancy on a low zinc diet.

  9. Zinc Status of Vegetarians during Pregnancy: A Systematic Review of Observational Studies and Meta-Analysis of Zinc Intake

    PubMed Central

    Foster, Meika; Herulah, Ursula Nirmala; Prasad, Ashlini; Petocz, Peter; Samman, Samir

    2015-01-01

    Pregnant women are vulnerable to a low zinc status due to the additional zinc demands associated with pregnancy and foetal development. The present systematic review explores the relationship between habitual vegetarian diets and dietary zinc intake/status during pregnancy. The association between vegetarian diets and functional pregnancy outcome also is considered. A literature search was conducted of MEDLINE; PubMed; Embase; the Cochrane Library; Web of Science; and Scopus electronic databases up to September 2014. Six English-language observational studies qualified for inclusion in the systematic review. A meta-analysis was conducted that compared the dietary zinc intake of pregnant vegetarian and non-vegetarian (NV) groups; the zinc intake of vegetarians was found to be lower than that of NV (−1.38 ± 0.35 mg/day; p < 0.001); and the exclusion of low meat eaters from the analysis revealed a greater difference (−1.53 ± 0.44 mg/day; p = 0.001). Neither vegetarian nor NV groups met the recommended dietary allowance (RDA) for zinc. In a qualitative synthesis; no differences were found between groups in serum/plasma zinc or in functional outcomes associated with pregnancy. In conclusion; pregnant vegetarian women have lower zinc intakes than NV control populations and both groups consume lower than recommended amounts. Further information is needed to determine whether physiologic adaptations in zinc metabolism are sufficient to meet maternal and foetal requirements during pregnancy on a low zinc diet. PMID:26056918

  10. Etude expérimentale des écoulements darcéens à travers un lit de fibres rigides empilées aléatoirement: influence de la porosité

    NASA Astrophysics Data System (ADS)

    Rahli, O.; Tadrist, L.; Miscevic, M.; Santini, R.

    1995-11-01

    Experimental studies have been carried out on fluid flow through porous media made up of randomly packed monodisperse fibers. The fibers of fixed diameter have an aspect ratio (L/d) varying between 4 and 70 given porosities of the porous media varying between 0.35 and 0.90. The relationships between friction losses and superficial velocity have been systematically determined for each porous medium. A detailed analysis is carried out for low fluid velocities. The influence of flow direction on pressure drop is studied along two perpendicular directions: it is found that fibrous media behave globally in isotropic manner. The permeability and the Kozeny Carman parameter k_k are deduced from experimental results. The variations of the permeability increase exponentially with the porosity. The Kozeny Carman parameter k_k is a decreasing function of the porosity ɛ(L/d) and tends asymptotically to a value close to that deduced from a modified Ergun relation. The important decrease, observed for small aspect ratios, is certainly an effect of the cut sections of fibers. This effect becomes negligible for larger aspect ratios. The results in terms of permeability and of Kozeny Carman parameter k_k are systematically compared to those deduced from various theoretical models. Generally, these models consider cylinders arranged in simple network, the flow being either parallel or perpendicular to the axis of cylinders. The variation laws of the parameter k_k, deduced from different models, present important discrepancies with our experimental results. The theoretical models, established for regular arrays of fibers do not correctly describe the behavior of randomly packed fibers. Des études expérimentales de l'écoulement d'un fluide à travers un milieu poreux constitué de fibres monodisperses empilées aléatoirement sont réalisées. Les milieux fibreux étudiés ont des porosités variant de 0,35 à 0,90. Ces porosités sont obtenues à l'aide de fibres dont le rapport

  11. The Work of Ambroise Tardieu: The First Definitive Description of Child Abuse

    ERIC Educational Resources Information Center

    Roche, A.J.; Fortin, G.; Labbe, J.; Brown, J.; Chadwick, D.

    2005-01-01

    The first important monograph describing the battered child syndrome was written in 1860 by Ambroise Tardieu, a French forensic physician. Here is a translation of his article, published in the Annales d'hygiene publique et de medecine legale, with the title ''Etude medico-legale sur les sevices et mauvais traitements exerces sur des enfants.''…

  12. Zinc oxide varistors and/or resistors

    DOEpatents

    Arnold, W.D. Jr.; Bond, W.D.; Lauf, R.J.

    1993-07-27

    Varistors and/or resistors are described that include doped zinc oxide gel microspheres. The doped zinc oxide gel microspheres preferably have from about 60 to about 95% by weight zinc oxide and from about 5 to about 40% by weight dopants based on the weight of the zinc oxide. The dopants are a plurality of dopants selected from silver salts, boron oxide, silicon oxide and hydrons oxides of aluminum, bismuth, cobalt, chromium, manganese, nickel, and antimony.

  13. Long life, rechargeable nickel-zinc battery

    NASA Technical Reports Server (NTRS)

    Luksha, E.

    1974-01-01

    A production version of the inorganic separator was evaluated for improving the life of the nickel-zinc system. Nickel-zinc cells (7-10 Ah capacities) of different electrode separator configurations were constructed and tested. The nickel-zinc cells using the inorganic separator encasing the zinc electrode, the nickel electrode, or both electrodes had shorter lives than cells using Visking and cellophane separation. Cells with the inorganic separation all fell below 70% of their theoretical capacity within 30 cycles, but the cells constructed with organic separation required 80 cycles. Failure of the cells using the ceramic separator was irreversible capacity degradation due to zinc loss through cracks developed in the inorganic separator. Zinc loss through the separator was minimized with the use of combinations of the inorganic separator with Visking and cellophane. Cells using the combined separation operated 130 duty cycles before degrading to 70% of their theoretical capacity.

  14. Stabilized nickel-zinc battery

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Himy, A.; Wagner, O.C.

    An alkaline nickel-zinc cell which has (1) a nickel-nickel hydroxide cathode; (2) a zinc-zinc oxide anode containing (A) a corrosion inhibitor such as PBO, SNO2, Tl2O3, in(OH)3 or mixtures thereof; (B) a slight corrosion accelerator such as cdo, bi2o3, ga2o3, or mixtures thereof; and (C) a zinc active material; (3) a mass-transport separator; (4) an alkaline electrolyte; and (5) means for charging the cell with an interrupted current having a frequency of from more than zero to 16 hertz with a rest period of not less than 60 milliseconds. Another desirable feature is the use of a pressure-cutoff switch tomore » terminate charging when the internal pressure of the cell reaches a selected value in the range of from 5 to 8 psig.« less

  15. Factors influencing zinc status of apparently healthy indians.

    PubMed

    Agte, Vaishali V; Chiplonkar, Shashi A; Tarwadi, Kirtan V

    2005-10-01

    To identify dietary, environmental and socio-economic factors associated with mild zinc deficiency, three zinc status indices; erythrocyte membrane zinc (RBCMZn), plasma zinc and super oxide dismutase (SOD) were assessed in free living and apparently healthy Indian population. Dietary patterns of 232 men and 223 women (20-65 yr) from rural, industrial and urban regions of Western India were evaluated by food frequency questionnaire. RBCMZn was estimated using atomic absorption spectrometry, hemoglobin and serum ceruloplasmin by spectrophotometer. On a sub sample (48 men and 51 women) plasma zinc and SOD were also assessed. Mean RBCMZn was 0.5 +/- 0.1 micromols/g protein with 46% individuals showing zinc deficiency. Mean plasma zinc was 0.98 +/- 0.12 microg/mL with 25% men and 2.5% women having values below normal range. Mean SOD was 0.97 +/- 0.1 (u/mL cells). A significant positive correlation was observed between intakes of green leafy vegetables, other vegetables and milk products with RBCMZn status (p < 0.05). But these were not correlated with plasma zinc (p > 0.2). Cereal and legume intakes were negatively correlated with RBCMZn (p < 0.05) but positively correlated with plasma zinc (p < 0.05) and not correlated with SOD (p > 0.2). Fruit and other vegetable intake were positively correlated with SOD (p < 0.05) alone. Logistic regression analyses revealed that RBCMZn was positively associated with intakes of beta-carotene, zinc and environmental conditions and negatively associated with family size (p < 0.05). Plasma zinc indicated positive association with zinc, thiamin and riboflavin intakes (p < 0.05) and SOD showed negative association with iron and family size. RBCMZn was a more sensitive indicator of long-term zinc status than plasma zinc and SOD. Prominent determinants of zinc status were intakes of beta-carotene and zinc along with environmental conditions and family size.

  16. Multi-modular, tris(triphenylamine) zinc porphyrin-zinc phthalocyanine-fullerene conjugate as a broadband capturing, charge stabilizing, photosynthetic 'antenna-reaction center' mimic.

    PubMed

    Kc, Chandra B; Lim, Gary N; D'Souza, Francis

    2015-04-21

    A broadband capturing, charge stabilizing, photosynthetic antenna-reaction center model compound has been newly synthesized and characterized. The model compound is comprised of a zinc porphyrin covalently linked to three units of triphenylamine entities and a zinc phthalocyanine entity. The absorption and fluorescence spectra of zinc porphyrin complemented that of zinc phthalocyanine offering broadband coverage. Stepwise energy transfer from singlet excited triphenylamine to zinc porphyrin, and singlet excited zinc porphyrin to zinc phthalocyanine (kENT ∼ 10(11) s(-1)) was established from spectroscopic and time-resolved transient absorption techniques. Next, an electron acceptor, fullerene was introduced via metal-ligand axial coordination to both zinc porphyrin and zinc phthalocyanine centers, and they were characterized by spectroscopic and electrochemical techniques. An association constant of 4.9 × 10(4) M(-1) for phenylimidazole functionalized fullerene binding to zinc porphyrin, and 5.1 × 10(4) M(-1) for it binding to zinc phthalocyanine was obtained. An energy level diagram for the occurrence of different photochemical events within the multi-modular donor-acceptor conjugate was established from spectral and electrochemical data. Unlike the previous zinc porphyrin-zinc phthalocyanine-fullerene conjugates, the newly assembled donor-acceptor conjugate has been shown to undergo the much anticipated initial charge separation from singlet excited zinc porphyrin to the coordinated fullerene followed by a hole shift process to zinc phthalocyanine resulting in a long-lived charge separated state as revealed by femto- and nanosecond transient absorption spectroscopic techniques. The lifetime of the final charge separated state was about 100 ns.

  17. Prediction of Serum Zinc Levels in Mexican Children at 2 Years of Age Using a Food Frequency Questionnaire and Different Zinc Bioavailability Criteria

    PubMed Central

    Cantoral, Alejandra; Téllez-Rojo, Martha; Shamah-Levy, Teresa; Schnaas, Lourdes; Hernández-Ávila, Mauricio; Peterson, Karen; Ettinger, Adrienne

    2017-01-01

    Background The 2006 Mexican National Health and Nutrition Survey documented a prevalence of zinc deficiency of almost 30% in children aged one to two years old. Objective We sought to validate a Food Frequency Questionnaire (FFQ) for quantifying dietary bioavailable zinc intake in two-year old Mexican children accounting for phytic acid intake and using serum zinc as a reference. Methods This cross-sectional study was nested within a longitudinal birth cohort of 333 young children in Mexico City. Non-fasting serum zinc concentration was measured and dietary zinc intake was calculated on the basis of a semi-quantitative FFQ administered to their mothers. The relationship between dietary zinc intake and serum zinc was assessed using linear regression, adjusting for phytic acid intake, and analyzed according to two distinct international criteria to estimate bioavailable zinc. Models were stratified by zinc deficiency status. Results Dietary zinc, adjusted for phytic acid intake, explained the greatest proportion of the variance of serum zinc. For each mg of dietary zinc intake, serum zinc increased on average by 0.95 μg/dL (0.15 μmol/L) (p=0.06). When stratified by zinc status, this increase was 0.74 μg/dL (p=0.12) for each milligram of zinc consumed among children with adequate serum zinc (N=276) whereas among those children with zinc deficiency (N=57), serum zinc increased by only 0.11 μg/dL (p=0.82). Conclusion A semi-quantitative FFQ can be used for predicting serum zinc in relation to dietary intake in young children, particularly among those who are zinc-replete, and when phytic acid/phytate intake is considered. Future studies should be conducted accounting for both zinc status and dietary zinc inhibitors to further elucidate and validate these findings. PMID:26121697

  18. Zinc and the modulation of redox homeostasis

    PubMed Central

    Oteiza, Patricia I.

    2012-01-01

    Zinc, a redox inactive metal, has been long viewed as a component of the antioxidant network, and growing evidence points to its involvement in redox-regulated signaling. These actions are exerted through several mechanisms based on the unique chemical and functional properties of zinc. Overall, zinc contributes to maintain the cell redox balance through different mechanisms including: i) the regulation of oxidant production and metal-induced oxidative damage; ii) the dynamic association of zinc with sulfur in protein cysteine clusters, from which the metal can be released by nitric oxide, peroxides, oxidized glutathione and other thiol oxidant species; iii) zinc-mediated induction of the zinc-binding protein metallothionein, which releases the metal under oxidative conditions and act per se scavenging oxidants; iv) the involvement of zinc in the regulation of glutathione metabolism and of the overall protein thiol redox status; and v) a direct or indirect regulation of redox signaling. Findings of oxidative stress, altered redox signaling, and associated cell/tissue disfunction in cell and animal models of zinc deficiency, stress the relevant role of zinc in the preservation of cell redox homeostasis. However, while the participation of zinc in antioxidant protection, redox sensing, and redox-regulated signaling is accepted, the involved molecules, targets and mechanisms are still partially known and the subject of active research. PMID:22960578

  19. 21 CFR 172.399 - Zinc methionine sulfate.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Zinc methionine sulfate. 172.399 Section 172.399... CONSUMPTION Special Dietary and Nutritional Additives § 172.399 Zinc methionine sulfate. Zinc methionine... conditions: (a) The additive is the product of the reaction between equimolar amounts of zinc sulfate and DL...

  20. Process for preparing zinc oxide-based sorbents

    DOEpatents

    Gangwal, Santosh Kumar [Cary, NC; Turk, Brian Scott [Durham, NC; Gupta, Raghubir Prasad [Durham, NC

    2011-06-07

    The disclosure relates to zinc oxide-based sorbents, and processes for preparing and using them. The sorbents are preferably used to remove one or more reduced sulfur species from gas streams. The sorbents comprise an active zinc component, optionally in combination with one or more promoter components and/or one or more substantially inert components. The active zinc component is a two phase material, consisting essentially of a zinc oxide (ZnO) phase and a zinc aluminate (ZnAl.sub.2O.sub.4) phase. Each of the two phases is characterized by a relatively small crystallite size of typically less than about 500 Angstroms. Preferably the sorbents are prepared by converting a precursor mixture, comprising a precipitated zinc oxide precursor and a precipitated aluminum oxide precursor, to the two-phase, active zinc oxide containing component.

  1. Pseudomonas aeruginosa Trent and zinc homeostasis.

    PubMed

    Davies, Corey B; Harrison, Mark D; Huygens, Flavia

    2017-09-01

    Pseudomonas aeruginosa is a Gram-negative pathogen and the major cause of mortality in patients with cystic fibrosis. The mechanisms that P. aeruginosa strains use to regulate intracellular zinc have an effect on infection, antibiotic resistance and the propensity to form biofilms. However, zinc homeostasis in P. aeruginosa strains of variable infectivity has not been compared. In this study, zinc homeostasis in P. aeruginosa Trent, a highly infectious clinical strain, was compared to that of a laboratory P. aeruginosa strain, ATCC27853. Trent was able to tolerate higher concentrations of additional zinc in rich media than ATCC27853. Further, pre-adaptation to additional zinc enhanced the growth of Trent at non-inhibitory concentrations but the impact of pre-adaption on the growth of ATCC27853 under the same conditions was minimal. The results establish clear differences in zinc-induced responses in Trent and ATCC27853, and how zinc homeostasis can be a promising target for the development of novel antimicrobial strategies for P. aeruginosa infection in cystic fibrosis patients. © FEMS 2017. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  2. Changes in zinc status and zinc transporters expression in whole blood of patients with Systemic Inflammatory Response Syndrome (SIRS).

    PubMed

    Florea, Daniela; Molina-López, Jorge; Hogstrand, Christer; Lengyel, Imre; de la Cruz, Antonio Pérez; Rodríguez-Elvira, Manuel; Planells, Elena

    2018-09-01

    Critically ill patients develop severe stress, inflammation and a clinical state that may raise the utilization and metabolic replacement of many nutrients and especially zinc, depleting their body reserves. This study was designed to assess the zinc status in critical care patients with systemic inflammatory response syndrome (SIRS), comparing them with a group of healthy people, and studying the association with expression of zinc transporters. This investigation was a prospective, multicentre, comparative, observational and analytic study. Twelve critically ill patients from different hospitals and 12 healthy subjects from Granada, Spain, all with informed consent were recruited. Data on daily nutritional assessment, ICU severity scores, inflammation, clinical and nutritional parameters, plasma and blood cell zinc concentrations, and levels of transcripts for zinc transporters in whole blood were taken at admission and at the seventh day of the ICU stay. Zinc levels on critical ill patient are diminish comparing with the healthy control (HS: 0.94 ± 0.19; CIPF: 0.67 ± 0.16 mg/dL). The 58% of critical ill patients showed zinc plasma deficiency at beginning of study while 50.0% of critical ill after 7 days of ICU stay. ZnT7, ZIP4 and ZIP9 were the zinc transporters with highest expression in whole blood. In general, all zinc transporters were significantly down-regulated (P < 0.05) in the critical ill population at admission in comparison with healthy subjects. Severity scores and inflammation were significantly associated (P < 0.05) with zinc plasma levels, and zinc transporters ZIP3, ZIP4, ZIP8, ZnT6, ZnT7. Expression of 11 out of 24 zinc transporters was analysed, and ZnT1, ZnT4, ZnT5 and ZIP4, which were downregulated by more than 3-fold in whole blood of patients. In summary, in our study an alteration of zinc status was related with the severity-of-illness scores and inflammation in critical ill patients since admission in ICU stay. SIRS

  3. Evaluation de l'intergiciel de communication DDS pour son utilisation dans le domaine avionique

    NASA Astrophysics Data System (ADS)

    Levesque-Landry, Kevin

    Les aeronefs modernes doivent combler de plus en plus de fonctionnalites afin de satisfaire les besoins de la clientele. De ce fait, les besoins en communications des systemes avioniques sont grandissants. De plus, la portabilite et la reutilisabilite des applications sont des defis d'actualite dans le domaine avionique. De ce fait, ce projet de recherche vise a faire une evaluation de la technologie d'intergiciel de service de distribution de donnees (DDS) pour son utilisation dans le domaine avionique. Cette technologie permettrait de reduire la complexite des communications et faciliter la portabilite et reutilisabilite des applications grâce a son interface standardisee. Dans ce projet de recherche, la norme DDS est tout d'abord etudiee pour cibler les fonctionnalites qui sont utiles au domaine avionique. Les differentes polices de qualite de services sont ainsi etudiees et denotent la flexibilite de la technologie DDS. Un intergiciel DDS est egalement evalue dans un environnement de laboratoire afin de mesurer l'impact de l'utilisation de cette technologie sur les performances de latence ainsi que sur l'utilisation de la bande passante. Les resultats montrent une faible augmentation de la latence moyenne lorsque l'intergiciel DDS est utilise. L'intergiciel DDS est egalement utilise dans une etude de cas avec un AFCS (automatic flight control system) afin de quantifier les effets de son utilisation sur une application avionique. Les resultats montrent que l'utilisation de l'intergiciel DDS n'empeche pas l'AFCS d'atteindre la stabilite, mais qu'elle ralentit l'atteinte de cette derniere. Finalement, une etude de cas est effectuee afin de valider que la technologie DDS peut etre utilisee pour construire des systemes redondants. Les resultats montrent que l'intergiciel DDS permet de faire de la redondance de reserve sans avoir un impact visible sur les performances du systeme redondant.

  4. Maternal Zinc Intakes and Homeostatic Adjustments during Pregnancy and Lactation

    PubMed Central

    Donangelo, Carmen Marino; King, Janet C.

    2012-01-01

    Zinc plays critical roles during embryogenesis, fetal growth, and milk secretion, which increase the zinc need for pregnancy and lactation. Increased needs can be met by increasing the dietary zinc intake, along with making homeostatic adjustments in zinc utilization. Potential homeostatic adjustments include changes in circulating zinc, increased zinc absorption, decreased zinc losses, and changes in whole body zinc kinetics. Although severe zinc deficiency during pregnancy has devastating effects, systematic reviews and meta-analysis of the effect of maternal zinc supplementation on pregnancy outcomes have consistently shown a limited benefit. We hypothesize, therefore, that zinc homeostatic adjustments during pregnancy and lactation improve zinc utilization sufficiently to provide the increased zinc needs in these stages and, therefore, mitigate immediate detrimental effects due to a low zinc intake. The specific questions addressed are the following: How is zinc utilization altered during pregnancy and lactation? Are those homeostatic adjustments influenced by maternal zinc status, dietary zinc, or zinc supplementation? These questions are addressed by critically reviewing results from published human studies on zinc homeostasis during pregnancy and lactation carried out in different populations worldwide. PMID:22852063

  5. Vacuolar zinc transporter Zrc1 is required for detoxification of excess intracellular zinc in the human fungal pathogen Cryptococcus neoformans.

    PubMed

    Cho, Minsu; Hu, Guanggan; Caza, Mélissa; Horianopoulos, Linda C; Kronstad, James W; Jung, Won Hee

    2018-01-01

    Zinc is an important transition metal in all living organisms and is required for numerous biological processes. However, excess zinc can also be toxic to cells and cause cellular stress. In the model fungus Saccharomyces cerevisiae, a vacuolar zinc transporter, Zrc1, plays important roles in the storage and detoxification of excess intracellular zinc to protect the cell. In this study, we identified an ortholog of the S. cerevisiae ZRC1 gene in the human fungal pathogen Cryptococcus neoformans. Zrc1 was localized in the vacuolar membrane in C. neoformans, and a mutant lacking ZRC1 showed significant growth defects under high-zinc conditions. These results suggested a role for Zrc1 in zinc detoxification. However, contrary to our expectation, the expression of Zrc1 was induced in cells grown in zinc-limited conditions and decreased upon the addition of zinc. These expression patterns were similar to those of Zip1, the high-affinity zinc transporter in the plasma membrane of C. neoformans. Furthermore, we used the zrc1 mutant in a murine model of cryptococcosis to examine whether a mammalian host could inhibit the survival of C. neoformans using zinc toxicity. We found that the mutant showed no difference in virulence compared with the wildtype strain. This result suggests that Zrc1-mediated zinc detoxification is not required for the virulence of C. neoformans, and imply that zinc toxicity may not be an important aspect of the host immune response to the fungus.

  6. High performance zinc anode for battery applications

    NASA Technical Reports Server (NTRS)

    Casey, John E., Jr. (Inventor)

    1998-01-01

    An improved zinc anode for use in a high density rechargeable alkaline battery is disclosed. A process for making the zinc electrode comprises electrolytic loading of the zinc active material from a slightly acidic zinc nitrate solution into a substrate of nickel, copper or silver. The substrate comprises a sintered plaque having very fine pores, a high surface area, and 80-85 percent total initial porosity. The residual porosity after zinc loading is approximately 25-30%. The electrode of the present invention exhibits reduced zinc mobility, shape change and distortion, and demonstrates reduced dendrite buildup cycling of the battery. The disclosed battery is useful for applications requiring high energy density and multiple charge capability.

  7. Zinc Regulation of Aminopeptidase B Involved in Neuropeptide Production

    PubMed Central

    Hwang, Shin-Rong; Hook, Vivian

    2009-01-01

    Aminopeptidase B (AP-B) is a metallopeptidase that removes basic residues from the N-termini of neuropeptide substrates in secretory vesicles. This study assessed zinc regulation of AP-B activity, since secretory vesicles contain endogenous zinc. AP-B was inhibited by zinc at concentrations typically present in secretory vesicles. Zinc effects were dependent on concentration, incubation time, and the molar ratio of zinc to enzyme. AP-B activity was recovered upon removal of zinc. AP-B with zinc became susceptible to degradation by trypsin, suggesting that zinc alters enzyme conformation. Zinc regulation demonstrates the metallopeptidase property of AP-B. PMID:18571504

  8. Method for the regeneration of spent molten zinc chloride

    DOEpatents

    Zielke, Clyde W.; Rosenhoover, William A.

    1981-01-01

    In a process for regenerating spent molten zinc chloride which has been used in the hydrocracking of coal or ash-containing polynuclear aromatic hydrocarbonaceous materials derived therefrom and which contains zinc chloride, zinc oxide, zinc oxide complexes and ash-containing carbonaceous residue, by incinerating the spent molten zinc chloride to vaporize the zinc chloride for subsequent condensation to produce a purified molten zinc chloride: an improvement comprising the use of clay in the incineration zone to suppress the vaporization of metals other than zinc. Optionally water is used in conjunction with the clay to further suppress the vaporization of metals other than zinc.

  9. Serum zinc, copper, retinol-binding protein, prealbumin, and ceruloplasmin concentrations in infants receiving intravenous zinc and copper supplementation.

    PubMed

    Lockitch, G; Godolphin, W; Pendray, M R; Riddell, D; Quigley, G

    1983-02-01

    One hundred twenty-seven newborn infants requiring parenteral nutrition were randomly assigned to receive differing amounts of zinc (40 to 400 micrograms/kg/day) and copper (20 or 40 micrograms/kg/day) supplementation within five birth weight groups (600 to 2,500 gm). The serum zinc concentration remained relatively constant in the group receiving the most zinc supplementation after two weeks of therapy, but declined sharply in the groups receiving less supplementation. No effect of increased copper intake was noted on ceruloplasmin values, but a difference in serum copper concentrations was noted at two weeks. No correlation was noted between serum zinc and copper values or among those for serum zinc, retinol-binding protein, and prealbumin. Reference ranges were defined for serum zinc, copper, retinol-binding protein, prealbumin, and ceruloplasmin in the preterm infant.

  10. 21 CFR 73.1991 - Zinc oxide.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... amounts consistent with good manufacturing practice. (d) Labeling. The color additive and any mixtues... ADDITIVES EXEMPT FROM CERTIFICATION Drugs § 73.1991 Zinc oxide. (a) Identity. (1) The color additive zinc...). It is principally composed of Zn. (2) Color additive mixtures for drug use made with zinc oxide may...

  11. 21 CFR 182.8988 - Zinc gluconate.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Zinc gluconate. 182.8988 Section 182.8988 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients § 182.8988 Zinc gluconate. (a) Product. Zinc gluconate. (b...

  12. 21 CFR 182.8994 - Zinc stearate.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Zinc stearate. 182.8994 Section 182.8994 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients § 182.8994 Zinc stearate. (a) Product. Zinc stearate prepared from...

  13. 21 CFR 182.8997 - Zinc sulfate.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Zinc sulfate. 182.8997 Section 182.8997 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients § 182.8997 Zinc sulfate. (a) Product. Zinc sulfate. (b) Conditions of...

  14. 21 CFR 182.8985 - Zinc chloride.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Zinc chloride. 182.8985 Section 182.8985 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients § 182.8985 Zinc chloride. (a) Product. Zinc chloride. (b) Conditions...

  15. 21 CFR 182.8994 - Zinc stearate.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Zinc stearate. 182.8994 Section 182.8994 Food and... CONSUMPTION (CONTINUED) SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients § 182.8994 Zinc stearate. (a) Product. Zinc stearate prepared from stearic acid free from chickedema factor. (b) Conditions of use. This...

  16. 21 CFR 182.8994 - Zinc stearate.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Zinc stearate. 182.8994 Section 182.8994 Food and... CONSUMPTION (CONTINUED) SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients § 182.8994 Zinc stearate. (a) Product. Zinc stearate prepared from stearic acid free from chickedema factor. (b) Conditions of use. This...

  17. 21 CFR 182.8988 - Zinc gluconate.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Zinc gluconate. 182.8988 Section 182.8988 Food and... CONSUMPTION (CONTINUED) SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients § 182.8988 Zinc gluconate. (a) Product. Zinc gluconate. (b) Conditions of use. This substance is generally recognized as safe when used...

  18. 21 CFR 182.8988 - Zinc gluconate.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Zinc gluconate. 182.8988 Section 182.8988 Food and... CONSUMPTION (CONTINUED) SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients § 182.8988 Zinc gluconate. (a) Product. Zinc gluconate. (b) Conditions of use. This substance is generally recognized as safe when used...

  19. Zinc activates damage-sensing TRPA1 ion channels.

    PubMed

    Hu, Hongzhen; Bandell, Michael; Petrus, Matt J; Zhu, Michael X; Patapoutian, Ardem

    2009-03-01

    Zinc is an essential biological trace element. It is required for the structure or function of over 300 proteins, and it is increasingly recognized for its role in cell signaling. However, high concentrations of zinc have cytotoxic effects, and overexposure to zinc can cause pain and inflammation through unknown mechanisms. Here we show that zinc excites nociceptive somatosensory neurons and causes nociception in mice through TRPA1, a cation channel previously shown to mediate the pungency of wasabi and cinnamon through cysteine modification. Zinc activates TRPA1 through a unique mechanism that requires zinc influx through TRPA1 channels and subsequent activation via specific intracellular cysteine and histidine residues. TRPA1 is highly sensitive to intracellular zinc, as low nanomolar concentrations activate TRPA1 and modulate its sensitivity. These findings identify TRPA1 as an important target for the sensory effects of zinc and support an emerging role for zinc as a signaling molecule that can modulate sensory transmission.

  20. Biomarkers of Nutrition for Development (BOND)—Zinc Review12345

    PubMed Central

    King, Janet C; Brown, Kenneth H; Gibson, Rosalind S; Krebs, Nancy F; Lowe, Nicola M; Siekmann, Jonathan H; Raiten, Daniel J

    2016-01-01

    Zinc is required for multiple metabolic processes as a structural, regulatory, or catalytic ion. Cellular, tissue, and whole-body zinc homeostasis is tightly controlled to sustain metabolic functions over a wide range of zinc intakes, making it difficult to assess zinc insufficiency or excess. The BOND (Biomarkers of Nutrition for Development) Zinc Expert Panel recommends 3 measurements for estimating zinc status: dietary zinc intake, plasma zinc concentration (PZC), and height-for-age of growing infants and children. The amount of dietary zinc potentially available for absorption, which requires an estimate of dietary zinc and phytate, can be used to identify individuals and populations at risk of zinc deficiency. PZCs respond to severe dietary zinc restriction and to zinc supplementation; they also change with shifts in whole-body zinc balance and clinical signs of zinc deficiency. PZC cutoffs are available to identify individuals and populations at risk of zinc deficiency. However, there are limitations in using the PZC to assess zinc status. PZCs respond less to additional zinc provided in food than to a supplement administered between meals, there is considerable interindividual variability in PZCs with changes in dietary zinc, and PZCs are influenced by recent meal consumption, the time of day, inflammation, and certain drugs and hormones. Insufficient data are available on hair, urinary, nail, and blood cell zinc responses to changes in dietary zinc to recommend these biomarkers for assessing zinc status. Of the potential functional indicators of zinc, growth is the only one that is recommended. Because pharmacologic zinc doses are unlikely to enhance growth, a growth response to supplemental zinc is interpreted as indicating pre-existing zinc deficiency. Other functional indicators reviewed but not recommended for assessing zinc nutrition in clinical or field settings because of insufficient information are the activity or amounts of zinc-dependent enzymes

  1. 21 CFR 582.5997 - Zinc sulfate.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 6 2013-04-01 2013-04-01 false Zinc sulfate. 582.5997 Section 582.5997 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS... 1 § 582.5997 Zinc sulfate. (a) Product. Zinc sulfate. (b) Conditions of use. This substance is...

  2. 21 CFR 582.5997 - Zinc sulfate.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 6 2012-04-01 2012-04-01 false Zinc sulfate. 582.5997 Section 582.5997 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS... 1 § 582.5997 Zinc sulfate. (a) Product. Zinc sulfate. (b) Conditions of use. This substance is...

  3. 21 CFR 182.8991 - Zinc oxide.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 3 2014-04-01 2014-04-01 false Zinc oxide. 182.8991 Section 182.8991 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients § 182.8991 Zinc oxide. (a) Product. Zinc oxide. (b) Conditions of use...

  4. 21 CFR 582.5997 - Zinc sulfate.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 6 2011-04-01 2011-04-01 false Zinc sulfate. 582.5997 Section 582.5997 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS... 1 § 582.5997 Zinc sulfate. (a) Product. Zinc sulfate. (b) Conditions of use. This substance is...

  5. 21 CFR 582.5985 - Zinc chloride.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 6 2011-04-01 2011-04-01 false Zinc chloride. 582.5985 Section 582.5985 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS... 1 § 582.5985 Zinc chloride. (a) Product. Zinc chloride. (b) Conditions of use. This substance is...

  6. 21 CFR 582.5997 - Zinc sulfate.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Zinc sulfate. 582.5997 Section 582.5997 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS... 1 § 582.5997 Zinc sulfate. (a) Product. Zinc sulfate. (b) Conditions of use. This substance is...

  7. 21 CFR 182.8991 - Zinc oxide.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Zinc oxide. 182.8991 Section 182.8991 Food and... CONSUMPTION (CONTINUED) SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients § 182.8991 Zinc oxide. (a) Product. Zinc oxide. (b) Conditions of use. This substance is generally recognized as safe when used in...

  8. 21 CFR 582.5991 - Zinc oxide.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Zinc oxide. 582.5991 Section 582.5991 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS... 1 § 582.5991 Zinc oxide. (a) Product. Zinc oxide. (b) Conditions of use. This substance is generally...

  9. 21 CFR 582.5988 - Zinc gluconate.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Zinc gluconate. 582.5988 Section 582.5988 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS... 1 § 582.5988 Zinc gluconate. (a) Product. Zinc gluconate. (b) Conditions of use. This substance is...

  10. 21 CFR 182.8985 - Zinc chloride.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Zinc chloride. 182.8985 Section 182.8985 Food and... CONSUMPTION (CONTINUED) SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients § 182.8985 Zinc chloride. (a) Product. Zinc chloride. (b) Conditions of use. This substance is generally recognized as safe when used in...

  11. 21 CFR 182.8997 - Zinc sulfate.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Zinc sulfate. 182.8997 Section 182.8997 Food and... CONSUMPTION (CONTINUED) SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients § 182.8997 Zinc sulfate. (a) Product. Zinc sulfate. (b) Conditions of use. This substance is generally recognized as safe when used in...

  12. 21 CFR 582.5994 - Zinc stearate.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Zinc stearate. 582.5994 Section 582.5994 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS... 1 § 582.5994 Zinc stearate. (a) Product. Zinc stearate prepared from stearic acid free from chick...

  13. 21 CFR 582.5994 - Zinc stearate.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 6 2011-04-01 2011-04-01 false Zinc stearate. 582.5994 Section 582.5994 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS... 1 § 582.5994 Zinc stearate. (a) Product. Zinc stearate prepared from stearic acid free from chick...

  14. 21 CFR 182.8991 - Zinc oxide.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Zinc oxide. 182.8991 Section 182.8991 Food and... CONSUMPTION (CONTINUED) SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients § 182.8991 Zinc oxide. (a) Product. Zinc oxide. (b) Conditions of use. This substance is generally recognized as safe when used in...

  15. 21 CFR 582.5988 - Zinc gluconate.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 6 2011-04-01 2011-04-01 false Zinc gluconate. 582.5988 Section 582.5988 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS... 1 § 582.5988 Zinc gluconate. (a) Product. Zinc gluconate. (b) Conditions of use. This substance is...

  16. 21 CFR 582.5991 - Zinc oxide.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 6 2011-04-01 2011-04-01 false Zinc oxide. 582.5991 Section 582.5991 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS... 1 § 582.5991 Zinc oxide. (a) Product. Zinc oxide. (b) Conditions of use. This substance is generally...

  17. 21 CFR 182.8997 - Zinc sulfate.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 3 2011-04-01 2011-04-01 false Zinc sulfate. 182.8997 Section 182.8997 Food and... CONSUMPTION (CONTINUED) SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients § 182.8997 Zinc sulfate. (a) Product. Zinc sulfate. (b) Conditions of use. This substance is generally recognized as safe when used in...

  18. 21 CFR 582.5985 - Zinc chloride.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Zinc chloride. 582.5985 Section 582.5985 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS... 1 § 582.5985 Zinc chloride. (a) Product. Zinc chloride. (b) Conditions of use. This substance is...

  19. 21 CFR 182.8985 - Zinc chloride.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 3 2010-04-01 2009-04-01 true Zinc chloride. 182.8985 Section 182.8985 Food and... CONSUMPTION (CONTINUED) SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients § 182.8985 Zinc chloride. (a) Product. Zinc chloride. (b) Conditions of use. This substance is generally recognized as safe when used in...

  20. Quantification des besoins en intrants antipaludiques: contribution à l'actualisation des hypothèses pour la quantification des intrants de prise en charge des cas de paludisme grave en République Démocratique du Congo

    PubMed Central

    Likwela, Joris Losimba; Otokoye, John Otshudiema

    2015-01-01

    Les formes graves de paludisme à Plasmodium falciparum sont une cause majeure de décès des enfants de moins de 5 ans en Afrique Sub-saharienne. Un traitement rapide dépend de la disponibilité de médicaments appropriés au niveau des points de prestation de service. La fréquence des ruptures de stock des commodités antipaludiques, en particuliers celles utilisées pour le paludisme grave, avait nécessité une mise à jour des hypothèses de quantification. Les données issues de la collecte de routine du PNLP de 2007 à 2012 ont été comparées à celles rapportés par d'autres pays africains et utilisées pour orienter les discussions au cours d'un atelier organisé par le PNLP et ses partenaires techniques et financiers afin de dégager un consensus national. La proportion des cas de paludisme rapportés comme grave en RDC est resté autour d'une médiane de 7% avec un domaine de variation de 6 à 9%. Hormis la proportion rapportée au Kenya (2%), les pays africains ont rapporté une proportion de cas grave variant entre 5 et 7%. Il apparaît que la proportion de 1% précédemment utilisée pour la quantification en RDC a été sous-estimée dans le contexte de la gestion des cas graves sur terrain. Un consensus s'est dégagé autour de la proportion de 5% étant entendu que des efforts de renforcement des capacités seraient déployés afin d'améliorer le diagnostic au niveau des points de prestation des services. PMID:26213595

  1. Effect of modifying agents on the hydrophobicity and yield of zinc borate synthesized by zinc oxide

    NASA Astrophysics Data System (ADS)

    Acarali, Nil Baran; Bardakci, Melek; Tugrul, Nurcan; Derun, Emek Moroydor; Piskin, Sabriye

    2013-06-01

    The aim of this study was to synthesize zinc borate using zinc oxide, reference boric acid, and reference zinc borate (reference ZB) as the seed, and to investigate the effects of modifying agents and reaction parameters on the hydrophobicity and yield, respectively. The reaction parameters include reaction time (1-5 h), reactant ratio (H3BO3/ZnO by mass: 2-5), seed ratio (seed crystal/(H3BO3+ZnO) by mass: 0-2wt%), reaction temperature (50-120°C), cooling temperature (10-80°C), and stirring rate (400-700 r/min); the modifying agents involve propylene glycol (PG, 0-6wt%), kerosene (1wt%-6wt%), and oleic acid (OA, 1wt%-6wt%) with solvents (isopropyl alcohol (IPA), ethanol, and methanol). The results of reaction yield obtained from either magnetically or mechanically stirred systems were compared. Zinc borate produced was characterized by X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), and contact angle tests to identify the hydrophobicity. In conclusion, zinc borate is synthesized successfully under the optimized reaction conditions, and the different modifying agents with various solvents affect the hydrophobicity of zinc borate.

  2. Zinc for the common cold.

    PubMed

    Singh, Meenu; Das, Rashmi R

    2013-06-18

    The common cold is one of the most widespread illnesses and is a leading cause of visits to the doctor and absenteeism from school and work. Trials conducted in high-income countries since 1984 investigating the role of zinc for the common cold symptoms have had mixed results. Inadequate treatment masking and reduced bioavailability of zinc from some formulations have been cited as influencing results. To assess whether zinc (irrespective of the zinc salt or formulation used) is efficacious in reducing the incidence, severity and duration of common cold symptoms. In addition, we aimed to identify potential sources of heterogeneity in results obtained and to assess their clinical significance. In this updated review, we searched CENTRAL (2012, Issue 12), MEDLINE (1966 to January week 2, 2013), EMBASE (1974 to January 2013), CINAHL (1981 to January 2013), Web of Science (1985 to January 2013), LILACS (1982 to January 2013), WHO ICTRP and clinicaltrials.gov. Randomised, double-blind, placebo-controlled trials using zinc for at least five consecutive days to treat, or for at least five months to prevent the common cold. Two review authors independently extracted data and assessed trial quality. Five trials were identified in the updated searches in January 2013 and two of them did not meet our inclusion criteria. We included 16 therapeutic trials (1387 participants) and two preventive trials (394 participants). Intake of zinc was associated with a significant reduction in the duration (days) (mean difference (MD) -1.03, 95% confidence interval (CI) -1.72 to -0.34) (P = 0.003) (I(2) statistic = 89%) but not the severity of common cold symptoms (MD -1.06, 95% CI -2.36 to 0.23) (P = 0.11) (I(2) statistic = 84%). The proportion of participants who were symptomatic after seven days of treatment was significantly smaller (odds ratio (OR) 0.45, 95% CI 0.20 to 1.00) (P = 0.05) than those in the control, (I(2 )statistic = 75%). The incidence rate ratio (IRR) of developing a

  3. Zinc halogen battery electrolyte composition with lead additive

    DOEpatents

    Henriksen, Gary L.

    1981-01-01

    This disclosure relates to a zinc halogen battery electrolyte composition containing an additive providing improved zinc-on-zinc recyclability. The improved electrolyte composition involves the use of a lead additive to inhibit undesirable irregular plating and reduce nodular or dendritic growth on the electrode surface. The lead-containing electrolyte composition of the present invention appears to influence not only the morphology of the base plate zinc, but also the morphology of the zinc-on-zinc replate. In addition, such lead-containing electrolyte compositions appear to reduce hydrogen formation.

  4. 21 CFR 558.78 - Bacitracin zinc.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 6 2010-04-01 2010-04-01 false Bacitracin zinc. 558.78 Section 558.78 Food and... in Animal Feeds § 558.78 Bacitracin zinc. (a) Specifications. Type A medicated articles containing bacitracin zinc equivalent to 10, 25, 40, or 50 grams per pound bacitracin. (b) Approvals. See No. 046573 in...

  5. 21 CFR 73.2991 - Zinc oxide.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 1 2010-04-01 2010-04-01 false Zinc oxide. 73.2991 Section 73.2991 Food and Drugs... ADDITIVES EXEMPT FROM CERTIFICATION Cosmetics § 73.2991 Zinc oxide. (a) Identity and specifications. The color additive zinc oxide shall conform in identity and specifications to the requirements of § 73.1991...

  6. 21 CFR 558.78 - Bacitracin zinc.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 6 2011-04-01 2011-04-01 false Bacitracin zinc. 558.78 Section 558.78 Food and... in Animal Feeds § 558.78 Bacitracin zinc. (a) Specifications. Type A medicated articles containing bacitracin zinc equivalent to 10, 25, 40, or 50 grams per pound bacitracin. (b) Approvals. See No. 046573 in...

  7. Speciation And Bioavailability Of Zinc In Amended Sediments

    EPA Science Inventory

    The speciation and bioavailability of zinc (Zn) in smelter-contaminated sediments was investigated as a function of phosphate (apatite) and organic amendment loading rate. Zinc species identified in preamendment sediment were zinc hydroxide-like phases, sphalerite, and zinc sorbe...

  8. The zinc dyshomeostasis hypothesis of Alzheimer's disease.

    PubMed

    Craddock, Travis J A; Tuszynski, Jack A; Chopra, Deepak; Casey, Noel; Goldstein, Lee E; Hameroff, Stuart R; Tanzi, Rudolph E

    2012-01-01

    Alzheimer's disease (AD) is the most common form of dementia in the elderly. Hallmark AD neuropathology includes extracellular amyloid plaques composed largely of the amyloid-β protein (Aβ), intracellular neurofibrillary tangles (NFTs) composed of hyper-phosphorylated microtubule-associated protein tau (MAP-tau), and microtubule destabilization. Early-onset autosomal dominant AD genes are associated with excessive Aβ accumulation, however cognitive impairment best correlates with NFTs and disrupted microtubules. The mechanisms linking Aβ and NFT pathologies in AD are unknown. Here, we propose that sequestration of zinc by Aβ-amyloid deposits (Aβ oligomers and plaques) not only drives Aβ aggregation, but also disrupts zinc homeostasis in zinc-enriched brain regions important for memory and vulnerable to AD pathology, resulting in intra-neuronal zinc levels, which are either too low, or excessively high. To evaluate this hypothesis, we 1) used molecular modeling of zinc binding to the microtubule component protein tubulin, identifying specific, high-affinity zinc binding sites that influence side-to-side tubulin interaction, the sensitive link in microtubule polymerization and stability. We also 2) performed kinetic modeling showing zinc distribution in extra-neuronal Aβ deposits can reduce intra-neuronal zinc binding to microtubules, destabilizing microtubules. Finally, we 3) used metallomic imaging mass spectrometry (MIMS) to show anatomically-localized and age-dependent zinc dyshomeostasis in specific brain regions of Tg2576 transgenic, mice, a model for AD. We found excess zinc in brain regions associated with memory processing and NFT pathology. Overall, we present a theoretical framework and support for a new theory of AD linking extra-neuronal Aβ amyloid to intra-neuronal NFTs and cognitive dysfunction. The connection, we propose, is based on β-amyloid-induced alterations in zinc ion concentration inside neurons affecting stability of polymerized

  9. 21 CFR 73.2991 - Zinc oxide.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 1 2013-04-01 2013-04-01 false Zinc oxide. 73.2991 Section 73.2991 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL LISTING OF COLOR ADDITIVES EXEMPT FROM CERTIFICATION Cosmetics § 73.2991 Zinc oxide. (a) Identity and specifications. The color additive zinc oxide shall conform in...

  10. 21 CFR 582.5991 - Zinc oxide.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 6 2013-04-01 2013-04-01 false Zinc oxide. 582.5991 Section 582.5991 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients and/or Dietary Supplements 1 § 582.5991 Zinc oxide. (a) Product. Zinc...

  11. 21 CFR 73.2991 - Zinc oxide.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 1 2012-04-01 2012-04-01 false Zinc oxide. 73.2991 Section 73.2991 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL LISTING OF COLOR ADDITIVES EXEMPT FROM CERTIFICATION Cosmetics § 73.2991 Zinc oxide. (a) Identity and specifications. The color additive zinc oxide shall conform in...

  12. 21 CFR 582.5991 - Zinc oxide.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 6 2012-04-01 2012-04-01 false Zinc oxide. 582.5991 Section 582.5991 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) ANIMAL DRUGS, FEEDS, AND RELATED PRODUCTS SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients and/or Dietary Supplements 1 § 582.5991 Zinc oxide. (a) Product. Zinc...

  13. Zinc release contributes to hypoglycemia-induced neuronal death.

    PubMed

    Suh, Sang Won; Garnier, Philippe; Aoyama, Koji; Chen, Yongmei; Swanson, Raymond A

    2004-08-01

    Neurons exposed to zinc exhibit activation of poly(ADP-ribose) polymerase-1 (PARP-1), an enzyme that normally participates in DNA repair but promotes cell death when extensively activated. Endogenous, vesicular zinc in brain is released to the extracellular space under conditions causing neuronal depolarization. Here, we used a rat model of insulin-induced hypoglycemia to assess the role of zinc release in PARP-1 activation and neuronal death after severe hypoglycemia. Zinc staining with N-(6-methoxy-8-quinolyl)-para-toluenesulfonamide (TSQ) showed depletion of presynaptic vesicular zinc from hippocampal mossy fiber terminals and accumulation of weakly bound zinc in hippocampal CA1 cell bodies after severe hypoglycemia. Intracerebroventricular injection of the zinc chelator calcium ethylene-diamine tetraacetic acid (CaEDTA) blocked the zinc accumulation and significantly reduced hypoglycemia-induced neuronal death. CaEDTA also attenuated the accumulation of poly(ADP-ribose), the enzymatic product of PARP-1, in hippocampal neurons. These results suggest that zinc translocation is an intermediary step linking hypoglycemia to PARP-1 activation and neuronal death.

  14. Zinc for the common cold.

    PubMed

    Singh, Meenu; Das, Rashmi R

    2011-02-16

    The common cold is one of the most widespread illnesses and is a leading cause of visits to the doctor and absenteeism from school and work. Trials conducted since 1984 investigating the role of zinc for the common cold symptoms have had mixed results. Inadequate treatment masking and reduced bioavailability of zinc from some formulations have been cited as influencing results. To assess the effect of zinc on common cold symptoms. We searched CENTRAL (2010, Issue 2) which contains the Acute Respiratory Infections Group's Specialised Register, MEDLINE (1966 to May week 3, 2010) and EMBASE (1974 to June 2010). Randomised, double-blind, placebo-controlled trials using zinc for at least five consecutive days to treat, or for at least five months to prevent the common cold. Two review authors independently extracted data and assessed trial quality. We included 13 therapeutic trials (966 participants) and two preventive trials (394 participants). Intake of zinc is associated with a significant reduction in the duration (standardized mean difference (SMD) -0.97; 95% confidence interval (CI) -1.56 to -0.38) (P = 0.001), and severity of common cold symptoms (SMD -0.39; 95% CI -0.77 to -0.02) (P = 0.04). There was a significant difference between the zinc and control group for the proportion of participants symptomatic after seven days of treatment (OR 0.45; 95% CI 0.2 to 1.00) (P = 0.05). The incidence rate ratio (IRR) of developing a cold (IRR 0.64; 95% CI 0.47 to 0.88) (P = 0.006), school absence (P = 0.0003) and prescription of antibiotics (P < 0.00001) was lower in the zinc group. Overall adverse events (OR 1.59; 95% CI 0.97 to 2.58) (P = 0.06), bad taste (OR 2.64; 95% CI 1.91 to 3.64) (P < 0.00001) and nausea (OR 2.15; 95% CI 1.44 to 3.23) (P = 0.002) were higher in the zinc group. Zinc administered within 24 hours of onset of symptoms reduces the duration and severity of the common cold in healthy people. When supplemented for at least five months, it reduces cold

  15. LiZIP3 is a cellular zinc transporter that mediates the tightly regulated import of zinc in Leishmania infantum parasites

    PubMed Central

    Carvalho, Sandra; da Silva, Rosa Barreira; Shawki, Ali; Castro, Helena; Lamy, Márcia; Eide, David; Costa, Vítor; Mackenzie, Bryan; Tomás, Ana M.

    2016-01-01

    Summary Cellular zinc homeostasis ensures that the intracellular concentration of this element is kept within limits that enable its participation in critical physiological processes without exerting toxic effects. We report here the identification and characterization of the first mediator of zinc homeostasis in Leishmania infantum, LiZIP3, a member of the ZIP family of divalent metal-ion transporters. The zinc transporter activity of LiZIP3 was first disclosed by its capacity to rescue the growth of Saccharomyces cerevisiae strains deficient in zinc acquisition. Subsequent expression of LiZIP3 in Xenopus laevis oocytes was shown to stimulate the uptake of a broad range of metal ions, among which Zn2+ was the preferred LiZIP3 substrate (K0.5 ≈ 0.1 μM). Evidence that LiZIP3 functions as a zinc importer in L. infantum came from the observations that the protein locates to the cell membrane and that its overexpression leads to augmented zinc internalization. Importantly, expression and cell-surface location of LiZIP3 are lost when parasites face high zinc bioavailability. LiZIP3 decline in response to zinc is regulated at the mRNA level in a process involving (a) short-lived protein(s). Collectively, our data reveal that LiZIP3 enables L. infantum to acquire zinc in a highly regulated manner, hence contributing to zinc homeostasis. PMID:25644708

  16. Caracterisation des proprietes acoustiques des materiaux poreux a cellules ouvertes et a matrice rigide ou souple

    NASA Astrophysics Data System (ADS)

    Salissou, Yacoubou

    L'objectif global vise par les travaux de cette these est d'ameliorer la caracterisation des proprietes macroscopiques des materiaux poreux a structure rigide ou souple par des approches inverses et indirectes basees sur des mesures acoustiques faites en tube d'impedance. La precision des approches inverses et indirectes utilisees aujourd'hui est principalement limitee par la qualite des mesures acoustiques obtenues en tube d'impedance. En consequence, cette these se penche sur quatre problemes qui aideront a l'atteinte de l'objectif global precite. Le premier probleme porte sur une caracterisation precise de la porosite ouverte des materiaux poreux. Cette propriete en est une de passage permettant de lier la mesure des proprietes dynamiques acoustiques d'un materiau poreux aux proprietes effectives de sa phase fluide decrite par les modeles semi-phenomenologiques. Le deuxieme probleme traite de l'hypothese de symetrie des materiaux poreux selon leur epaisseur ou un index et un critere sont proposes pour quantifier l'asymetrie d'un materiau. Cette hypothese est souvent source d'imprecision des methodes de caracterisation inverses et indirectes en tube d'impedance. Le critere d'asymetrie propose permet ainsi de s'assurer de l'applicabilite et de la precision de ces methodes pour un materiau donne. Le troisieme probleme vise a mieux comprendre le probleme de transmission sonore en tube d'impedance en presentant pour la premiere fois un developpement exact du probleme par decomposition d'ondes. Ce developpement permet d'etablir clairement les limites des nombreuses methodes existantes basees sur des tubes de transmission a 2, 3 ou 4 microphones. La meilleure comprehension de ce probleme de transmission est importante puisque c'est par ce type de mesures que des methodes permettent d'extraire successivement la matrice de transfert d'un materiau poreux et ses proprietes dynamiques intrinseques comme son impedance caracteristique et son nombre d'onde complexe. Enfin, le

  17. Maternal and fetal plasma zinc in pre-eclampsia.

    PubMed

    Bassiouni, B A; Foda, A I; Rafei, A A

    1979-04-01

    Zinc is important for fetal growth and is involved in several important enzyme systems. Maternal and umbilical plasma zinc concentrations were determined in 52 parturient women with mild and severe pre-eclampsia, and were compared with those obtained from 20 women in labor whose pregnancies had progressed normally. A decrease in maternal as well as umbilical plasma zinc concentrations was observed in pre-eclamptic women, and this decrease was statistically significant in severe pre-eclampsia. The causes of these changes in plasma zinc concentrations in pre-eclampsia were discussed, and the possible adverse effects of zinc deficiency on the mother and fetus were mentioned. Low plasma zinc concentrations in pre-eclampsia may be a sign of zinc deficiency, implying possible risks to the mother and her fetus. It is recommended that maintenance of adequate dietary zinc nutrition during pregnancy, and particularly in pre-eclampsia, is important.

  18. Role of nutritional zinc in the prevention of osteoporosis.

    PubMed

    Yamaguchi, Masayoshi

    2010-05-01

    Zinc is known as an essential nutritional factor in the growth of the human and animals. Bone growth retardation is a common finding in various conditions associated with dietary zinc deficiency. Bone zinc content has been shown to decrease in aging, skeletal unloading, and postmenopausal conditions, suggesting its role in bone disorder. Zinc has been demonstrated to have a stimulatory effect on osteoblastic bone formation and mineralization; the metal directly activates aminoacyl-tRNA synthetase, a rate-limiting enzyme at translational process of protein synthesis, in the cells, and it stimulates cellular protein synthesis. Zinc has been shown to stimulate gene expression of the transcription factors runt-related transcription factor 2 (Runx2) that is related to differentiation into osteoblastic cells. Moreover, zinc has been shown to inhibit osteoclastic bone resorption due to inhibiting osteoclast-like cell formation from bone marrow cells and stimulating apoptotic cell death of mature osteoclasts. Zinc has a suppressive effect on the receptor activator of nuclear factor (NF)-kappaB ligand (RANKL)-induced osteoclastogenesis. Zinc transporter has been shown to express in osteoblastic and osteoclastic cells. Zinc protein is involved in transcription. The intake of dietary zinc causes an increase in bone mass. beta-Alanyl-L: -histidinato zinc (AHZ) is a zinc compound, in which zinc is chelated to beta-alanyl-L: -histidine. The stimulatory effect of AHZ on bone formation is more intensive than that of zinc sulfate. Zinc acexamate has also been shown to have a potent-anabolic effect on bone. The oral administration of AHZ or zinc acexamate has the restorative effect on bone loss under various pathophysiologic conditions including aging, skeletal unloading, aluminum bone toxicity, calcium- and vitamin D-deficiency, adjuvant arthritis, estrogen deficiency, diabetes, and fracture healing. Zinc compounds may be designed as new supplementation factor in the prevention and

  19. Prognostic value of serum zinc levels in patients with acute HC/zinc chloride smoke inhalation

    PubMed Central

    Xie, Fei; Zhang, Xingang; Xie, Lixin

    2017-01-01

    Abstract Hexachloroethane (HC)/zinc chloride (ZnCl, smoke bomb) exposure in the military setting results in lung injury which is uncommon and has been rarely described in previous studies. The aim of this study is to investigate the correlation between the serum zinc in patients with HC/ZnCl smoke inhalation lung injury and disease severity. A total of 15 patients with HC/ZnCl-related conditions were recruited in this study. The serum zinc level and the pulmonary function tests and liver function tests including total lung capacity (TLC), forced vital capacity (FVC), forced expiratory pressure in 1 second (FEV1), alanine aminotransferase (ALT), and aspartate transaminase (AST) were analyzed. Eleven cases had mild clinical manifestations. Four cases rapidly developed features typical of severe adult respiratory distress syndrome. The level of serum zinc was increased, but FVC, FEV1, and TLC was decreased significantly in the moderate and severe cases. In addition, the serum zinc level correlated well with the TLC, FVC, and FEV1 (r = −0.587, −0.626, −0.617, respectively; P = .027, .017, .019, respectively). The 4 cases in moderate and severe group had delayed impairment of liver functions after the accident. This study suggested that the serum zinc level may be associated with the severity of lung and liver injuries after HC/ZnCl smoke inhalation. PMID:28953660

  20. Recent advances in zinc-air batteries.

    PubMed

    Li, Yanguang; Dai, Hongjie

    2014-08-07

    Zinc-air is a century-old battery technology but has attracted revived interest recently. With larger storage capacity at a fraction of the cost compared to lithium-ion, zinc-air batteries clearly represent one of the most viable future options to powering electric vehicles. However, some technical problems associated with them have yet to be resolved. In this review, we present the fundamentals, challenges and latest exciting advances related to zinc-air research. Detailed discussion will be organized around the individual components of the system - from zinc electrodes, electrolytes, and separators to air electrodes and oxygen electrocatalysts in sequential order for both primary and electrically/mechanically rechargeable types. The detrimental effect of CO2 on battery performance is also emphasized, and possible solutions summarized. Finally, other metal-air batteries are briefly overviewed and compared in favor of zinc-air.

  1. Decrease of non-point zinc runoff using porous concrete.

    PubMed

    Harada, Shigeki; Komuro, Yoshinori

    2010-01-01

    The use of porous concrete columns to decrease the amount of zinc in stormwater runoff is examined. The concentration of zinc in a simulated stormwater fluid (zinc acetate solution), fed through concrete columns (slashed circle10x10cm) decreased by 50-81%, suggesting physical adsorption of zinc by the porous concrete. We propose the use of porous concrete columns (slashed circle50x10cm) as the base of sewage traps. Longer-term, high-zinc concentration monitoring revealed that porous concrete blocks adsorb 38.6mgcm(-3) of zinc. A period of no significant zinc runoff (with an acceptable concentration of zinc in runoff of 0.03mgL(-1), a zinc concentration equal to the Japanese Environmental Standard) is estimated for 41years using a 1-ha catchment area with 20 porous concrete sewage traps. Scanning electron microscopy of the porous concrete used in this study indicates that the needle-like particles formed by hydration action significantly increase zinc adsorption. Evidence suggests that the hydrant is ettringite and has an important role in zinc adsorption, the resulting immobilization of zinc and the subsequent effects on groundwater quality. Copyright 2009 Elsevier Ltd. All rights reserved.

  2. Modulation of extrasynaptic NMDA receptors by synaptic and tonic zinc.

    PubMed

    Anderson, Charles T; Radford, Robert J; Zastrow, Melissa L; Zhang, Daniel Y; Apfel, Ulf-Peter; Lippard, Stephen J; Tzounopoulos, Thanos

    2015-05-19

    Many excitatory synapses contain high levels of mobile zinc within glutamatergic vesicles. Although synaptic zinc and glutamate are coreleased, it is controversial whether zinc diffuses away from the release site or whether it remains bound to presynaptic membranes or proteins after its release. To study zinc transmission and quantify zinc levels, we required a high-affinity rapid zinc chelator as well as an extracellular ratiometric fluorescent zinc sensor. We demonstrate that tricine, considered a preferred chelator for studying the role of synaptic zinc, is unable to efficiently prevent zinc from binding low-nanomolar zinc-binding sites, such as the high-affinity zinc-binding site found in NMDA receptors (NMDARs). Here, we used ZX1, which has a 1 nM zinc dissociation constant and second-order rate constant for binding zinc that is 200-fold higher than those for tricine and CaEDTA. We find that synaptic zinc is phasically released during action potentials. In response to short trains of presynaptic stimulation, synaptic zinc diffuses beyond the synaptic cleft where it inhibits extrasynaptic NMDARs. During higher rates of presynaptic stimulation, released glutamate activates additional extrasynaptic NMDARs that are not reached by synaptically released zinc, but which are inhibited by ambient, tonic levels of nonsynaptic zinc. By performing a ratiometric evaluation of extracellular zinc levels in the dorsal cochlear nucleus, we determined the tonic zinc levels to be low nanomolar. These results demonstrate a physiological role for endogenous synaptic as well as tonic zinc in inhibiting extrasynaptic NMDARs and thereby fine tuning neuronal excitability and signaling.

  3. Intracellular zinc distribution in mitochondria, ER and the Golgi apparatus

    PubMed Central

    Lu, Qiping; Haragopal, Hariprakash; Slepchenko, Kira G; Stork, Christian; Li, Yang V

    2016-01-01

    Zinc (Zn2+) is required for numerous cellular functions. As such, the homeostasis and distribution of intracellular zinc can influence cellular metabolism and signaling. However, the exact distribution of free zinc within live cells remains elusive. Previously we showed the release of zinc from thapsigargin/IP3-sensitive endoplasmic reticulum (ER) storage in cortical neurons. In the present study, we investigated if other cellular organelles also contain free chelatable zinc and function as organelle storage for zinc. To identify free zinc within the organelles, live cells were co-stained with Zinpyr-1, a zinc fluorescent dye, and organelle-specific fluorescent dyes (MitoFluor Red 589: mitochondria; ER Tracker Red: endoplasmic reticulum; BODIPY TR ceramide: Golgi apparatus; Syto Red 64: nucleus). We examined organelles that represent potential storing sites for intracellular zinc. We showed that zinc fluorescence staining was co-localized with MitoFluor Red 589, ER Tracker Red, and BODIPY TR ceramide respectively, suggesting the presence of free zinc in mitochondria, endoplasmic reticulum, and the Golgi apparatus. On the other hand, cytosol and nucleus had nearly no detectable zinc fluorescence. It is known that nucleus contains high amount of zinc binding proteins that have high zinc binding affinity. The absence of zinc fluorescence suggests that there is little free zinc in these two regions. It also indicates that the zinc fluorescence detected in mitochondria, ER and Golgi apparatus represents free chelatable zinc. Taken together, our results support that these organelles are potential zinc storing organelles during cellular zinc homeostasis. PMID:27186321

  4. Modulation of extrasynaptic NMDA receptors by synaptic and tonic zinc

    PubMed Central

    Anderson, Charles T.; Radford, Robert J.; Zastrow, Melissa L.; Zhang, Daniel Y.; Apfel, Ulf-Peter; Lippard, Stephen J.; Tzounopoulos, Thanos

    2015-01-01

    Many excitatory synapses contain high levels of mobile zinc within glutamatergic vesicles. Although synaptic zinc and glutamate are coreleased, it is controversial whether zinc diffuses away from the release site or whether it remains bound to presynaptic membranes or proteins after its release. To study zinc transmission and quantify zinc levels, we required a high-affinity rapid zinc chelator as well as an extracellular ratiometric fluorescent zinc sensor. We demonstrate that tricine, considered a preferred chelator for studying the role of synaptic zinc, is unable to efficiently prevent zinc from binding low-nanomolar zinc-binding sites, such as the high-affinity zinc-binding site found in NMDA receptors (NMDARs). Here, we used ZX1, which has a 1 nM zinc dissociation constant and second-order rate constant for binding zinc that is 200-fold higher than those for tricine and CaEDTA. We find that synaptic zinc is phasically released during action potentials. In response to short trains of presynaptic stimulation, synaptic zinc diffuses beyond the synaptic cleft where it inhibits extrasynaptic NMDARs. During higher rates of presynaptic stimulation, released glutamate activates additional extrasynaptic NMDARs that are not reached by synaptically released zinc, but which are inhibited by ambient, tonic levels of nonsynaptic zinc. By performing a ratiometric evaluation of extracellular zinc levels in the dorsal cochlear nucleus, we determined the tonic zinc levels to be low nanomolar. These results demonstrate a physiological role for endogenous synaptic as well as tonic zinc in inhibiting extrasynaptic NMDARs and thereby fine tuning neuronal excitability and signaling. PMID:25947151

  5. Eléments traces dans le sérum des enfants malnutris et bien nourris vivants à Lubumbashi et Kawama dans un contexte d'un environnement de pollution minière

    PubMed Central

    Musimwa, Aimée Mudekereza; Kanteng, Gray Wakamb; Kitoko, Hermann Tamubango; Luboya, Oscar Numbi

    2016-01-01

    Introduction La place des éléments traces métalliques essentiels en nutrition humaine ne peut plus être ignorée. Les déficits d'apports, les carences secondaires souvent sous – estimées, et les carences iatrogènes font le lit de pathologies telles que les infections et autres. D'où leurs dosages ont une importance particulière pour en évaluer la gravité et faciliter une prise en charge précoce ou améliorer le régime alimentaire. Cette étude a eu pour objectif de déterminer le profil sanguin en éléments traces (cuivre, sélénium, zinc, fer, chrome, cobalt, etc) chez les enfants malnutris et biens nourris dans un milieu minier à Lubumbashi. Méthodes Trois cents onze cas ont été colligés, 182 malnutris et 129 biens nourris, dans une étude descriptive transversale, effectuée de juillet 2013 à décembre 2014. Pour lequel un échantillonnage exhaustif a été réalisé. Le dosage des métaux dans le sérum s'est fait à l’ ICP-OES (spectrométrie de masse à plasma gon induit) au laboratoire de l'Office Congolais de Contrôle de Lubumbashi. Résultats Les oligoéléments essentiels (cuivre, zinc, sélénium et fer) se retrouvent à des concentrations très basses chez les enfants malnutris comme chez les biens nourris. L'arsenic, le cadmium, le magnésium et le manganèse se présentent à des concentrations normales par rapport aux valeurs de références chez les enfants biens nourris. L'antimoine, le chrome, le plomb et le cobalt se retrouvent élevés chez les malnutris et biens nourris. Le nickel est normal chez les malnutris et les biens nourris. Le magnésium, manganèse se sont présentés à des taux très bas chez les enfants malnutris. Conclusion Les enfants malnutris et biens nourris présentent une malnutrition aux oligo-éléments essentiels associés aux éléments traces métalliques. Ce qui permet de supposer qu'une carence en micronutriments essentiel favorise l'absorption des métaux lourds. PMID:27583075

  6. The Role of Zinc Layer During Wetting of Aluminium on Zinc-coated Steel in Laser Brazing and Welding

    NASA Astrophysics Data System (ADS)

    Gatzen, M.; Radel, T.; Thomy, C.; Vollertsen, F.

    The zinc layer of zinc-coated steel is known to be a crucial factor for the spreading of liquid aluminium on the coated surface. For industrial brazing and welding processes these zinc-coatings enable a fluxless joining between aluminium and steel in many cases. Yet, the reason for the beneficial effect of the zinc to the wetting process is not completely understood. Fundamental investigations on the wetting behaviour of single aluminium droplets on different zinc-coated steel surfaces have revealed a distinct difference between coated surfaces at room temperature and at elevated temperature regarding the influence of different coating thicknesses. In this paper the case of continuous laser brazing and welding processes of aluminium and commercial galvanized zinc-coated steel sheets are presented. It is shown that in the case of bead-on-plate laser beam brazing, the coating thickness has a measureable effect on the resulting wetting angle and length but does not have a significant impact in case of overlap laser beam welding. This might be linked to different heat transfer conditions. The results also strongly indicate that proper initialbreakup of oxide layers is still required to accomplish good wetting on zinc-coated surfaces.

  7. 21 CFR 73.1991 - Zinc oxide.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 21 Food and Drugs 1 2014-04-01 2014-04-01 false Zinc oxide. 73.1991 Section 73.1991 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL LISTING OF COLOR ADDITIVES EXEMPT FROM CERTIFICATION Drugs § 73.1991 Zinc oxide. (a) Identity. (1) The color additive zinc oxide is a white or yellow-white amorphous...

  8. 21 CFR 73.1991 - Zinc oxide.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 1 2013-04-01 2013-04-01 false Zinc oxide. 73.1991 Section 73.1991 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL LISTING OF COLOR ADDITIVES EXEMPT FROM CERTIFICATION Drugs § 73.1991 Zinc oxide. (a) Identity. (1) The color additive zinc oxide is a white or yellow-white amorphous...

  9. 21 CFR 73.1991 - Zinc oxide.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 1 2012-04-01 2012-04-01 false Zinc oxide. 73.1991 Section 73.1991 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL LISTING OF COLOR ADDITIVES EXEMPT FROM CERTIFICATION Drugs § 73.1991 Zinc oxide. (a) Identity. (1) The color additive zinc oxide is a white or yellow-white amorphous...

  10. Bioavailability of zinc oxide added to corn tortilla is similar to that of zinc sulfate and is not affected by simultaneous addition of iron

    PubMed Central

    Rosado, Jorge L.; Díaz, Margarita; Muñoz, Elsa; Westcott, Jamie L.; González, Karla E.; Krebs, Nancy F.; Caamaño, María C.; Hambidge, Michael

    2013-01-01

    Background Corn tortilla is the staple food of Mexico and its fortification with zinc, iron, and other micronutrients is intended to reduce micronutrient deficiencies. However, no studies have been performed to determine the relative amount of zinc absorbed from the fortified product and whether zinc absorption is affected by the simultaneous addition of iron. Objective To compare zinc absorption from corn tortilla fortified with zinc oxide versus zinc sulfate and to determine the effect of simultaneous addition of two doses of iron on zinc bioavailability. Methods A randomized, double-blind, crossover design was carried out in two phases. In the first phase, 10 adult women received corn tortillas with either 20 mg/kg of zinc oxide added, 20 mg/kg of zinc sulfate added, or no zinc added. In the second phase, 10 adult women received corn tortilla with 20 mg/kg of zinc oxide added and either with no iron added or with iron added at one of two different levels. Zinc absorption was measured by the stable isotope method. Results The mean (± SEM) fractional zinc absorption from unfortified tortilla, tortilla fortified with zinc oxide, and tortilla fortified with zinc sulfate did not differ among treatments: 0.35 ± 0.07, 0.36 ± 0.05, and 0.37 ± 0.07, respectively. The three treatment groups with 0, 30, and 60 mg/kg of added iron had similar fractional zinc absorption (0.32 ± 0.04, 0.33 ± 0.02, and 0.32 ± 0.05, respectively) and similar amounts of zinc absorbed (4.8 ± 0.7, 4.5 ± 0.3, and 4.8 ± 0.7 mg/day, respectively). Conclusions Since zinc oxide is more stable and less expensive and was absorbed equally as well as zinc sulfate, we suggest its use for corn tortilla fortification. Simultaneous addition of zinc and iron to corn tortilla does not modify zinc bioavailability at iron doses of 30 and 60 mg/kg of corn flour. PMID:23424892

  11. Trends in incidence and early outcomes in a Black Afro-Caribbean population from 1999 to 2012: Etude Réalisée en Martinique et Centrée sur l'Incidence des Accidents Vasculaires Cérébraux II Study.

    PubMed

    Olindo, Stephane; Chausson, Nicolas; Mejdoubi, Mehdi; Jeannin, Severine; Rosillette, Karine; Saint-Vil, Martine; Signate, Aissatou; Edimonana-Kaptue, Mireille; Larraillet, Veronique; Cabre, Philippe; Smadja, Didier; Joux, Julien

    2014-11-01

    Seldom studies are available on trends in stroke incidence in blacks. We aimed to evaluate whether stroke risk prevention policies modified first-ever stroke incidence and outcomes in the black Afro-Caribbean population of Martinique. Etude Réalisée en Martinique et Centrée sur l'Incidence des Accidents Vasculaires Cérébraux (ERMANCIA) I and II are 2 sequential prospective population-based epidemiological studies. There have assessed temporal trends in first-ever stroke incidence, risk factors, pathological types, and early outcomes in the black Afro-Caribbean population of Martinique comparing two 12-month periods (1998-1999 and 2011-2012). Crude and age-standardized incidence and 30-day outcomes for stroke in the 2 study periods were compared using Poisson regression. We identified 580 and 544 first-ever strokes in the 2 studies. World age-standardized incidence rates decreased by 30.6% in overall (111 [95% confidence interval, 102-120] versus 77 [95% confidence interval, 70-84]). Rate decline was greater in women than in men (34% versus 26%) particularly in women aged 65 to 74 years (-69%) and 75 to 84 years (-43%). Frequencies of hypertension and diabetes mellitus were unchanged, whereas dyslipidemia, smoking, and atrial fibrillation significantly increased. Only ischemic stroke types showed significant rate reduction in overall and in women, incidence rate ratio (95% confidence intervals) of 0.69 (0.50-0.97) and 0.61 (0.42-0.88), respectively. The overall 30-day case-fatality ratio remained stable (19.3%/17.6%), whereas a better 30-day outcome was found (modified Rankin Score, ≤2 in 47%/37.6%; P=0.03). Over 13 years, there has been a significant decrease (30.6%) in the age-specific first-ever stroke incidence in our Afro-Carribean population. Although prevention policies seem effective, we need to focus on new risk factors limitation and on male population adherence to prevention program. © 2014 American Heart Association, Inc.

  12. Etude des mécanismes d'ionisation de H{2}O par interaction He^{*}(2 ^1S, 2 ^3S)/Ne^{*}(^3P{0}, ^3P{2})+H{2}O

    NASA Astrophysics Data System (ADS)

    Le Nadan, André; Sinou, Guillaume; Tuffin, Firmin

    1993-06-01

    Experimental observations of Penning ionisation of H{2}O by the helium metastables 21S and 23S and by the neon metastables ^3P{0} and ^3P{2} are reported. The kinetic energies of the ions created during the collision process (both parent and fragment) are analysed. Certain particularities of the experimental results are explained by involving the hypothesis of transfers of vibrational energy to kinetic energy. Furthermore, the forms of the energy distributions of the fragment ions are explained by th predissociation of the ^2B{2} state of H{2}O+. Nous avons étudié l'ionisation Penning de H{2}O par des métastables 21S et 23S de l'hélium, ainsi que ^3P{0} et ^3P{2} du néon. Nous avons analysé l'énergie cinétique des ions créés au cours de la collision (parents et fragments). Afin d'interpréter certaines particularités expérimentales, l'hypothèse de transferts d'énergie de vibration en énergie cinétique est proposées. Par ailleurs, les caractéristiques des distributions en énergie des ions fragments sont expliquées par la prédissociation de l'état ^2B{2} de H{2}O+.

  13. Horse Liver Alcohol Dehydrogenase: Zinc Coordination and Catalysis

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Plapp, Bryce V.; Savarimuthu, Baskar Raj; Ferraro, Daniel J.

    During catalysis by liver alcohol dehydrogenase (ADH), a water bound to the catalytic zinc is replaced by the oxygen of the substrates. The mechanism might involve a pentacoordinated zinc or a double-displacement reaction with participation by a nearby glutamate residue, as suggested by studies of human ADH3, yeast ADH1, and some other tetrameric ADHs. Zinc coordination and participation of water in the enzyme mechanism were investigated by X-ray crystallography. The apoenzyme and its complex with adenosine 5'-diphosphoribose have an open protein conformation with the catalytic zinc in one position, tetracoordinated by Cys-46, His-67, Cys-174, and a water molecule. The bidentatemore » chelators 2,2'-bipyridine and 1,10-phenanthroline displace the water and form a pentacoordinated zinc. The enzyme–NADH complex has a closed conformation similar to that of ternary complexes with coenzyme and substrate analogues; the coordination of the catalytic zinc is similar to that found in the apoenzyme, except that a minor, alternative position for the catalytic zinc is ~1.3 Å from the major position and closer to Glu-68, which could form the alternative coordination to the catalytic zinc. Complexes with NADH and N-1-methylhexylformamide or N-benzylformamide (or with NAD+ and fluoro alcohols) have the classical tetracoordinated zinc, and no water is bound to the zinc or the nicotinamide rings. The major forms of the enzyme in the mechanism have a tetracoordinated zinc, where the carboxylate group of Glu-68 could participate in the exchange of water and substrates on the zinc. Hydride transfer in the Michaelis complexes does not involve a nearby water.« less

  14. Horse Liver Alcohol Dehydrogenase: Zinc Coordination and Catalysis

    PubMed Central

    2017-01-01

    During catalysis by liver alcohol dehydrogenase (ADH), a water bound to the catalytic zinc is replaced by the oxygen of the substrates. The mechanism might involve a pentacoordinated zinc or a double-displacement reaction with participation by a nearby glutamate residue, as suggested by studies of human ADH3, yeast ADH1, and some other tetrameric ADHs. Zinc coordination and participation of water in the enzyme mechanism were investigated by X-ray crystallography. The apoenzyme and its complex with adenosine 5′-diphosphoribose have an open protein conformation with the catalytic zinc in one position, tetracoordinated by Cys-46, His-67, Cys-174, and a water molecule. The bidentate chelators 2,2′-bipyridine and 1,10-phenanthroline displace the water and form a pentacoordinated zinc. The enzyme–NADH complex has a closed conformation similar to that of ternary complexes with coenzyme and substrate analogues; the coordination of the catalytic zinc is similar to that found in the apoenzyme, except that a minor, alternative position for the catalytic zinc is ∼1.3 Å from the major position and closer to Glu-68, which could form the alternative coordination to the catalytic zinc. Complexes with NADH and N-1-methylhexylformamide or N-benzylformamide (or with NAD+ and fluoro alcohols) have the classical tetracoordinated zinc, and no water is bound to the zinc or the nicotinamide rings. The major forms of the enzyme in the mechanism have a tetracoordinated zinc, where the carboxylate group of Glu-68 could participate in the exchange of water and substrates on the zinc. Hydride transfer in the Michaelis complexes does not involve a nearby water. PMID:28640600

  15. Plasma in-liquid method for reduction of zinc oxide in zinc nanoparticle synthesis

    NASA Astrophysics Data System (ADS)

    Amaliyah, Novriany; Mukasa, Shinobu; Nomura, Shinfuku; Toyota, Hiromichi; Kitamae, Tomohide

    2015-02-01

    Metal air-batteries with high-energy density are expected to be increasingly applied in electric vehicles. This will require a method of recycling air batteries, and reduction of metal oxide by generating plasma in liquid has been proposed as a possible method. Microwave-induced plasma is generated in ethanol as a reducing agent in which zinc oxide is dispersed. Analysis by energy-dispersive x-ray spectrometry (EDS) and x-ray diffraction (XRD) reveals the reduction of zinc oxide. According to images by transmission electron microscopy (TEM), cubic and hexagonal metallic zinc particles are formed in sizes of 30 to 200 nm. Additionally, spherical fiber flocculates approximately 180 nm in diameter are present.

  16. Behavioral impairments in animal models for zinc deficiency

    PubMed Central

    Hagmeyer, Simone; Haderspeck, Jasmin Carmen; Grabrucker, Andreas Martin

    2015-01-01

    Apart from teratogenic and pathological effects of zinc deficiency such as the occurrence of skin lesions, anorexia, growth retardation, depressed wound healing, altered immune function, impaired night vision, and alterations in taste and smell acuity, characteristic behavioral changes in animal models and human patients suffering from zinc deficiency have been observed. Given that it is estimated that about 17% of the worldwide population are at risk for zinc deficiency and that zinc deficiency is associated with a variety of brain disorders and disease states in humans, it is of major interest to investigate, how these behavioral changes will affect the individual and a putative course of a disease. Thus, here, we provide a state of the art overview about the behavioral phenotypes observed in various models of zinc deficiency, among them environmentally produced zinc deficient animals as well as animal models based on a genetic alteration of a particular zinc homeostasis gene. Finally, we compare the behavioral phenotypes to the human condition of mild to severe zinc deficiency and provide a model, how zinc deficiency that is associated with many neurodegenerative and neuropsychological disorders might modify the disease pathologies. PMID:25610379

  17. Zinc stress induces copper depletion in Acinetobacter baumannii.

    PubMed

    Hassan, Karl A; Pederick, Victoria G; Elbourne, Liam D H; Paulsen, Ian T; Paton, James C; McDevitt, Christopher A; Eijkelkamp, Bart A

    2017-03-11

    The first row transition metal ions zinc and copper are essential to the survival of many organisms, although in excess these ions are associated with significant toxicity. Here, we examined the impact of zinc and copper stress on Acinetobacter baumannii, a common opportunistic pathogen. We show that extracellular zinc stress induces a copper-specific depletion phenotype in A. baumannii ATCC 17978. Supplementation with copper not only fails to rescue this phenotype, but further exacerbates the copper depletion. Extensive analysis of the A. baumannii ATCC 17978 genome identified 13 putative zinc/copper resistance efflux pumps. Transcriptional analyses show that four of these transporters are responsive to zinc stress, five to copper stress and seven to the combination of zinc and copper stress, thereby revealing a likely foundation for the zinc-induced copper starvation in A. baumannii. In addition, we show that zinc and copper play crucial roles in management of oxidative stress and the membrane composition of A. baumannii. Further, we reveal that zinc and copper play distinct roles in macrophage-mediated killing of this pathogen. Collectively, this study supports the targeting of metal ion homeostatic mechanisms as an effective antimicrobial strategy against multi-drug resistant bacterial pathogens.

  18. Hyper-dendritic nanoporous zinc foam anodes

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Chamoun, Mylad; Hertzberg, Benjamin J.; Gupta, Tanya

    The low cost, significant reducing potential, and relative safety of the zinc electrode is a common hope for a reductant in secondary batteries, but it is limited mainly to primary implementation due to shape change. In this work we exploit such shape change for the benefit of static electrodes through the electrodeposition of hyper-dendritic nanoporous zinc foam. Electrodeposition of zinc foam resulted in nanoparticles formed on secondary dendrites in a three-dimensional network with a particle size distribution of 54.1 - 96.0 nm. The nanoporous zinc foam contributed to highly oriented crystals, high surface area and more rapid kinetics in contrastmore » to conventional zinc in alkaline mediums. The anode material presented had a utilization of ~ 88% at full depth-of-discharge at various rates indicating a superb rate-capability. The rechargeability of Zn⁰/Zn²⁺ showed significant capacity retention over 100 cycles at a 40% depth-of-discharge to ensure that the dendritic core structure was imperforated. The dendritic architecture was densified upon charge-discharge cycling and presented superior performance compared to bulk zinc electrodes.« less

  19. Hyper-dendritic nanoporous zinc foam anodes

    DOE PAGES

    Chamoun, Mylad; Hertzberg, Benjamin J.; Gupta, Tanya; ...

    2015-04-24

    The low cost, significant reducing potential, and relative safety of the zinc electrode is a common hope for a reductant in secondary batteries, but it is limited mainly to primary implementation due to shape change. In this work we exploit such shape change for the benefit of static electrodes through the electrodeposition of hyper-dendritic nanoporous zinc foam. Electrodeposition of zinc foam resulted in nanoparticles formed on secondary dendrites in a three-dimensional network with a particle size distribution of 54.1 - 96.0 nm. The nanoporous zinc foam contributed to highly oriented crystals, high surface area and more rapid kinetics in contrastmore » to conventional zinc in alkaline mediums. The anode material presented had a utilization of ~ 88% at full depth-of-discharge at various rates indicating a superb rate-capability. The rechargeability of Zn⁰/Zn²⁺ showed significant capacity retention over 100 cycles at a 40% depth-of-discharge to ensure that the dendritic core structure was imperforated. The dendritic architecture was densified upon charge-discharge cycling and presented superior performance compared to bulk zinc electrodes.« less

  20. Zinc-Catalyzed Synthesis of Conjugated Dienoates through Unusual Cross-Couplings of Zinc Carbenes with Diazo Compounds.

    PubMed

    Mata, Sergio; González, María J; González, Jesús; López, Luis A; Vicente, Rubén

    2017-01-23

    Zinc-catalyzed selective cross-coupling of two carbene sources, such as vinyl diazo compounds and enynones, enabled the synthesis of conjugated dienoate derivatives. This reaction involved the unprecedented coupling of a zinc furyl carbene with vinyl diazo compounds through the γ-carbon. Alternatively, dienoates were also prepared by a commutative cross-coupling of zinc vinyl carbenes generated from cyclopropenes and simple diazo compounds. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

  1. Arsenite binding-induced zinc loss from PARP-1 is equivalent to zinc deficiency in reducing PARP-1 activity, leading to inhibition of DNA repair

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Sun, Xi; Zhou, Xixi; Du, Libo

    2014-01-15

    Inhibition of DNA repair is a recognized mechanism for arsenic enhancement of ultraviolet radiation-induced DNA damage and carcinogenesis. Poly(ADP-ribose) polymerase-1 (PARP-1), a zinc finger DNA repair protein, has been identified as a sensitive molecular target for arsenic. The zinc finger domains of PARP-1 protein function as a critical structure in DNA recognition and binding. Since cellular poly(ADP-ribosyl)ation capacity has been positively correlated with zinc status in cells, we hypothesize that arsenite binding-induced zinc loss from PARP-1 is equivalent to zinc deficiency in reducing PARP-1 activity, leading to inhibition of DNA repair. To test this hypothesis, we compared the effects ofmore » arsenite exposure with zinc deficiency, created by using the membrane-permeable zinc chelator TPEN, on 8-OHdG formation, PARP-1 activity and zinc binding to PARP-1 in HaCat cells. Our results show that arsenite exposure and zinc deficiency had similar effects on PARP-1 protein, whereas supplemental zinc reversed these effects. To investigate the molecular mechanism of zinc loss induced by arsenite, ICP-AES, near UV spectroscopy, fluorescence, and circular dichroism spectroscopy were utilized to examine arsenite binding and occupation of a peptide representing the first zinc finger of PARP-1. We found that arsenite binding as well as zinc loss altered the conformation of zinc finger structure which functionally leads to PARP-1 inhibition. These findings suggest that arsenite binding to PARP-1 protein created similar adverse biological effects as zinc deficiency, which establishes the molecular mechanism for zinc supplementation as a potentially effective treatment to reverse the detrimental outcomes of arsenic exposure. - Highlights: • Arsenite binding is equivalent to zinc deficiency in reducing PARP-1 function. • Zinc reverses arsenic inhibition of PARP-1 activity and enhancement of DNA damage. • Arsenite binding and zinc loss alter the conformation of

  2. Evaluation of Serum Levels of Zinc, Copper, Iron, and Zinc/Copper Ratio in Cutaneous Leishmaniasis

    PubMed Central

    Pourfallah, F; Javadian, S; Zamani, Z; Saghiri, R; Sadeghi, S; Zarea, B; Faiaz, Sh; Mirkhani, F; Fatemi, N

    2009-01-01

    Background: The purpose of this study was to evaluate the levels of zinc (Zn), copper (Cu), iron (Fe) and zinc/ copper ratio in the serum of patients with cutaneous leishmaniasis in Qom Province, center of Iran. Methods: Serum levels of zinc and copper were determined by flame atomic absorption spectrophotometer and serum iron concentration was measured by using an Auto Analyzer. The study group consisted of 60 patients with cutaneous leishmaniasis and the control group of 100 healthy volunteers from the same area who were not exposed to cutaneous leishmaniasis. Result: There were no statistically significant differences in age and body mass index between the two groups. Serum Zn (P< 0.001) and Fe (P< 0.05) levels were lower in patients with cutaneous leishmaniasis than the control group. We also found serum Cu concentration (P< 0.05) in the patient group was significantly higher than that of the control group. However, zinc/ copper ratio (P< 0.001) was lower in patients with cutaneous leishmaniasis than in the control group. Conclusion: Our data indicated that Zn/Cu ratio was significantly lower in patients with CL as compared to the controls. Earlier reports suggest that, this ratio imbalance could be a useful marker for immune dysfunction in leishmaniasis. There was also strong association of Zn, Cu and Fe with CL. It suggests the use of blood zinc, copper, iron concentration and the copper/zinc ratio (Zn/Cu), as a means for estimating the prognosis of CL. PMID:22808376

  3. Le niobate de lithium a haute temperature pour les applications ultrasons =

    NASA Astrophysics Data System (ADS)

    De Castilla, Hector

    L'objectif de ce travail de maitrise en sciences appliquees est de trouver puis etudier un materiau piezoelectrique qui est potentiellement utilisable dans les transducteurs ultrasons a haute temperature. En effet, ces derniers sont actuellement limites a des temperatures de fonctionnement en dessous de 300°C a cause de l'element piezoelectrique qui les compose. Palier a cette limitation permettrait des controles non destructifs par ultrasons a haute temperature. Avec de bonnes proprietes electromecaniques et une temperature de Curie elevee (1200°C), le niobate de lithium (LiNbO 3) est un bon candidat. Mais certaines etudes affirment que des processus chimiques tels que l'apparition de conductivite ionique ou l'emergence d'une nouvelle phase ne permettent pas son utilisation dans les transducteurs ultrasons au-dessus de 600°C. Cependant, d'autres etudes plus recentes ont montre qu'il pouvait generer des ultrasons jusqu'a 1000°C et qu'aucune conductivite n'etait visible. Une hypothese a donc emerge : une conductivite ionique est presente dans le niobate de lithium a haute temperature (>500°C) mais elle n'affecte que faiblement ses proprietes a hautes frequences (>100 kHz). Une caracterisation du niobate de lithium a haute temperature est donc necessaire afin de verifier cette hypothese. Pour cela, la methode par resonance a ete employee. Elle permet une caracterisation de la plupart des coefficients electromecaniques avec une simple spectroscopie d'impedance electrochimique et un modele reliant de facon explicite les proprietes au spectre d'impedance. Il s'agit de trouver les coefficients du modele permettant de superposer au mieux le modele avec les mesures experimentales. Un banc experimental a ete realise permettant de controler la temperature des echantillons et de mesurer leur impedance electrochimique. Malheureusement, les modeles actuellement utilises pour la methode par resonance sont imprecis en presence de couplages entre les modes de vibration. Cela

  4. Oral zinc for treating diarrhoea in children

    PubMed Central

    Lazzerini, Marzia; Wanzira, Humphrey

    2016-01-01

    Background In developing countries, diarrhoea causes around 500,000 child deaths annually. Zinc supplementation during acute diarrhoea is currently recommended by the World Health Organization (WHO) and the United Nations Children's Fund (UNICEF). Objectives To evaluate oral zinc supplementation for treating children with acute or persistent diarrhoea. Search methods We searched the Cochrane Infectious Diseases Group Specialized Register, CENTRAL (the Cochrane Library 2016, Issue 5), MEDLINE, Embase, LILACS, CINAHL, mRCT, and reference lists up to 30 September 2016. We also contacted researchers. Selection criteria Randomized controlled trials (RCTs) that compared oral zinc supplementation with placebo in children aged one month to five years with acute or persistent diarrhoea, including dysentery. Data collection and analysis Both review authors assessed trial eligibility and risk of bias, extracted and analysed data, and drafted the review. The primary outcomes were diarrhoea duration and severity. We summarized dichotomous outcomes using risk ratios (RR) and continuous outcomes using mean differences (MD) with 95% confidence intervals (CI). Where appropriate, we combined data in meta-analyses (using either a fixed-effect or random-effects model) and assessed heterogeneity. We assessed the certainty of the evidence using the GRADE approach. Main results Thirty-three trials that included 10,841 children met our inclusion criteria. Most included trials were conducted in Asian countries that were at high risk of zinc deficiency. Acute diarrhoea There is currently not enough evidence from well-conducted RCTs to be able to say whether zinc supplementation during acute diarrhoea reduces death or number of children hospitalized (very low certainty evidence). In children older than six months of age, zinc supplementation may shorten the average duration of diarrhoea by around half a day (MD −11.46 hours, 95% CI −19.72 to −3.19; 2581 children, 9 trials, low

  5. Fatigue of die cast zinc alloys

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Schrems, K.K.; Dogan, O.N.; Goodwin, F.E.

    2006-04-01

    The rotating bending fatigue limit of die cast zinc alloy 2, alloy 3, alloy 5, AcuZinc 5, and ZA-8 were determined as a part of an on-going program by ILZRO into the mechanical properties of die cast zinc. The stress-life (S-N) curves of alloys 3, 5, AcuZinc 5, and ZA-8 were determined previously. This presentation reports the results of the S-N curve for Alloy 2 and the calculated fatigue limits for all five alloys. During the previous stress-life testing, the samples were stopped at 10 million cycles and the fatigue limit for alloy 3, alloy 5, and AcuZinc 5 appearedmore » to be higher and the fatigue limit for ZA-8 appeared to be lower than the values reported in the literature. This was further investigated in alloy 5 and ZA-8 by testing continuous cast bulk alloy 5 and ZA-8.« less

  6. Fishy Business: Effect of Omega-3 Fatty Acids on Zinc Transporters and Free Zinc Availability in Human Neuronal Cells

    PubMed Central

    De Mel, Damitha; Suphioglu, Cenk

    2014-01-01

    Omega-3 (ω-3) fatty acids are one of the two main families of long chain polyunsaturated fatty acids (PUFA). The main omega-3 fatty acids in the mammalian body are α-linolenic acid (ALA), docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA). Central nervous tissues of vertebrates are characterized by a high concentration of omega-3 fatty acids. Moreover, in the human brain, DHA is considered as the main structural omega-3 fatty acid, which comprises about 40% of the PUFAs in total. DHA deficiency may be the cause of many disorders such as depression, inability to concentrate, excessive mood swings, anxiety, cardiovascular disease, type 2 diabetes, dry skin and so on. On the other hand, zinc is the most abundant trace metal in the human brain. There are many scientific studies linking zinc, especially excess amounts of free zinc, to cellular death. Neurodegenerative diseases, such as Alzheimer’s disease, are characterized by altered zinc metabolism. Both animal model studies and human cell culture studies have shown a possible link between omega-3 fatty acids, zinc transporter levels and free zinc availability at cellular levels. Many other studies have also suggested a possible omega-3 and zinc effect on neurodegeneration and cellular death. Therefore, in this review, we will examine the effect of omega-3 fatty acids on zinc transporters and the importance of free zinc for human neuronal cells. Moreover, we will evaluate the collective understanding of mechanism(s) for the interaction of these elements in neuronal research and their significance for the diagnosis and treatment of neurodegeneration. PMID:25195602

  7. Fishy business: effect of omega-3 fatty acids on zinc transporters and free zinc availability in human neuronal cells.

    PubMed

    De Mel, Damitha; Suphioglu, Cenk

    2014-08-15

    Omega-3 (ω-3) fatty acids are one of the two main families of long chain polyunsaturated fatty acids (PUFA). The main omega-3 fatty acids in the mammalian body are α-linolenic acid (ALA), docosahexaenoic acid (DHA) and eicosapentaenoic acid (EPA). Central nervous tissues of vertebrates are characterized by a high concentration of omega-3 fatty acids. Moreover, in the human brain, DHA is considered as the main structural omega-3 fatty acid, which comprises about 40% of the PUFAs in total. DHA deficiency may be the cause of many disorders such as depression, inability to concentrate, excessive mood swings, anxiety, cardiovascular disease, type 2 diabetes, dry skin and so on. On the other hand, zinc is the most abundant trace metal in the human brain. There are many scientific studies linking zinc, especially excess amounts of free zinc, to cellular death. Neurodegenerative diseases, such as Alzheimer's disease, are characterized by altered zinc metabolism. Both animal model studies and human cell culture studies have shown a possible link between omega-3 fatty acids, zinc transporter levels and free zinc availability at cellular levels. Many other studies have also suggested a possible omega-3 and zinc effect on neurodegeneration and cellular death. Therefore, in this review, we will examine the effect of omega-3 fatty acids on zinc transporters and the importance of free zinc for human neuronal cells. Moreover, we will evaluate the collective understanding of mechanism(s) for the interaction of these elements in neuronal research and their significance for the diagnosis and treatment of neurodegeneration.

  8. [Effect of cultivation in zinc media on the growth of and the degree of zinc in organic form in transgenic metallothionein mushroom].

    PubMed

    Sheng, Ji-Ping; Shen, Lin; Ru, Bing-Gen

    2009-03-01

    Metallothioneins (MTs) are a family of low molecular weight, cysteine-rich and metal-binding functional proteins. Transgenic MT mushroom can be used as functional food additives, but its zinc-enriching ability has not been studied systemically until now. The zinc contents in mycelia of transgenic MT mushroom (Pleurotus ostreatus) and wild type mushroom mycelia cultivated in different zinc concentration media were analyzed by ICP-OES. The growth status, zinc-enriching ability and degree of zinc in organic form (DZOF) were also analyzed. Results showed that MT mushroom mycelia grew rapidly, but the growth was inhibited when the zinc content in solid media was higher than 1.6 mmol x L(-1). MT mushroom mycelia could enrich more zinc than that of wild type, and the zinc content in MT mushroom mycelia could be 2.56-27.49 mg x kg(-1) when it was cultivated in a liquid media with 0.6-1.2 mmol x L(-1) zinc. DZOF of MT mushroom mycelia in a liquid media with 0.6 mmol x L(-1) zinc at 7 d was significantly higher (88.7%) than that in the wild type (82.1%, alpha = 0.05), but there was no significant difference in DZOF when the MT mushroom mycelia was cultivated in a liquid media with different zinc content at 7 d.

  9. Zinc supplementation in children with cystic fibrosis

    USDA-ARS?s Scientific Manuscript database

    Cystic fibrosis (CF) leads to malabsorption of macro- and micronutrients. Symptomatic zinc deficiency has been reported in CF but little is known about zinc homeostasis in children with CF. Zinc supplementation (Zn suppl) is increasingly common in children with CF but it is not without theoretcial r...

  10. 21 CFR 172.399 - Zinc methionine sulfate.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... FOR HUMAN CONSUMPTION (CONTINUED) FOOD ADDITIVES PERMITTED FOR DIRECT ADDITION TO FOOD FOR HUMAN CONSUMPTION Special Dietary and Nutritional Additives § 172.399 Zinc methionine sulfate. Zinc methionine... conditions: (a) The additive is the product of the reaction between equimolar amounts of zinc sulfate and DL...

  11. 21 CFR 172.399 - Zinc methionine sulfate.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... FOR HUMAN CONSUMPTION (CONTINUED) FOOD ADDITIVES PERMITTED FOR DIRECT ADDITION TO FOOD FOR HUMAN CONSUMPTION Special Dietary and Nutritional Additives § 172.399 Zinc methionine sulfate. Zinc methionine... conditions: (a) The additive is the product of the reaction between equimolar amounts of zinc sulfate and DL...

  12. Microwave Synthesis of Zinc Hydroxy Sulfate Nanoplates and Zinc Oxide Nanorods in the Classroom

    ERIC Educational Resources Information Center

    Dziedzic, Rafal M.; Gillian-Daniel, Anne Lynn; Peterson, Greta M.; Martínez-Herna´ndez, Kermin J.

    2014-01-01

    In this hands-on, inquiry-based lab, high school and undergraduate students learn about nanotechnology by synthesizing their own nanoparticles in a single class period. This simple synthesis of zinc oxide nanorods and zinc hydroxy sulfate nanoplates can be done in 15 min using a household microwave oven. Reagent concentration, reaction…

  13. Cytoprotection by Endogenous Zinc in the Vertebrate Retina

    PubMed Central

    Anastassov, Ivan; Ripps, Harris; Chappell, Richard L.

    2014-01-01

    Our recent studies have shown that endogenous zinc, co-released with glutamate from the synaptic terminals of vertebrate retinal photoreceptors, provides a feedback mechanism that reduces calcium entry and the concomitant vesicular release of glutamate. We hypothesized that zinc feedback may serve to protect the retina from glutamate excitotoxicity, and conducted in vivo experiments on the retina of the skate (Raja erinacea) to determine the effects of removing endogenous zinc by chelation. These studies showed that removal of zinc by injecting the zinc chelator histidine results in inner retinal damage similar to that induced by the glutamate receptor agonist kainic acid. In contrast, when an equimolar quantity of zinc followed the injection of histidine, the retinal cells were unaffected. Our results are a good indication that zinc, co-released with glutamate by photoreceptors, provides an auto-feedback system that plays an important cytoprotective role in the retina. PMID:24286124

  14. The desA and desB genes from Clostridium scindens ATCC 35704 encode steroid-17,20-desmolase.

    PubMed

    Devendran, Saravanan; Mythen, Sean M; Ridlon, Jason M

    2018-06-01

    Clostridium scindens is a gut microbe capable of removing the side-chain of cortisol, forming 11β-hydro-xyandrostenedione. A cortisol-inducible operon ( desABCD ) was previously identified in C. scindens ATCC 35704 by RNA-Seq. The desC gene was shown to encode a cortisol 20α-hydroxysteroid dehydrogenase (20α-HSDH). The desD encodes a protein annotated as a member of the major facilitator family, predicted to function as a cortisol transporter. The desA and desB genes are annotated as N-terminal and C-terminal transketolases, respectively. We hypothesized that the DesAB forms a complex and has steroid-17,20-desmolase activity. We cloned the desA and desB genes from C. scindens ATCC 35704 in pETDuet for overexpression in Escherichia coli The purified recombinant DesAB was determined to be a 142 ± 5.4 kDa heterotetramer. We developed an enzyme-linked continuous spectrophotometric assay to quantify steroid-17,20-desmolase. This was achieved by coupling DesAB-dependent formation of 11β-hydroxyandrostenedione with the NADPH-dependent reduction of the steroid 17-keto group by a recombinant 17β-HSDH from the filamentous fungus, Cochliobolus lunatus The pH optimum for the coupled assay was 7.0 and kinetic constants using cortisol as substrate were K m of 4.96 ± 0.57 µM and k cat of 0.87 ± 0.076 min -1 Substrate-specificity studies revealed that rDesAB recognized substrates regardless of 11β-hydroxylation, but had an absolute requirement for 17,21-dihydroxy 20-ketosteroids. Copyright © 2018 Devendran et al.

  15. Zinc transport in rabbit tissues. Some hormonal aspects of the turnover of zinc in female reproductive organs, liver and body fluids

    PubMed Central

    McIntosh, J. E. A.; Lutwak-Mann, C.

    1972-01-01

    1. To investigate the influence of hormonal conditions upon the kinetics of zinc transport, specific radioactivity of 65Zn was determined in certain tissues and fluids from unmated or pregnant rabbits during the first half of gestation. 2. Compartmental analysis was used to find the simplest mathematical model that simulated satisfactorily tracer behaviour. Models were fitted to experimental results by a numerical procedure using a computer. 3. The kinetics of zinc exchange in most tissues investigated could adequately be described by a three-compartment model, in which total tissue zinc content was divided into a rapidly exchanging pool, with a turnover time of about 1h, and a slowly exchanging pool, the turnover time of which was in liver 15h, in peak-stage corpus luteum 8h, and in the other tissues 30–70h. 4. In rabbit endometrium zinc transport varied with hormonal conditions, the turnover rate being higher in non-pregnant than pregnant endometrium. 5. Uptake of 65Zn by uterine fluid was slow, and in the free-lying embryos (blastocysts) slower still, in keeping with uterine fluid acting as carrier of zinc into the unimplanted embryos. 6. In placental tissue zinc transport varied with gestational stage. Foetal placenta exchanged zinc with blood plasma four times faster than maternal placenta. In foetuses zinc turnover time and flux equalled that of the slow zinc compartment in foetal placenta. 7. Corpus luteum on days 5–6 of gestation showed peak specific radioactivity and zinc flux values, which exceeded those of all other tissues. 8. In liver the slow zinc compartment had a higher rate of turnover than corresponding compartments in tissues other than peak-stage corpus luteum, but no hormone-dependent changes were observed. 9. Zinc uptake by erythrocytes was the slowest of all examined. PMID:5073239

  16. Recent trends and current practices for secondary processing of zinc and lead. Part II: zinc recovery from secondary sources.

    PubMed

    Sahu, Kamala Kanta; Agrawal, Archana; Pandey, Banshi Dhar

    2004-08-01

    Almost all metallurgical processes are associated with the generation of wastes and residues that may be hazardous or non-hazardous in nature depending upon the criteria specified by institutions such as the US Environment Protection Agency, etc. Wastes containing heavy and toxic metals such as arsenic, cadmium, chromium, nickel, lead, copper, mercury, zinc, etc., that are present beyond permissible limits deemed to be treated or disposed of, and non-hazardous wastes can be utilized for metal recovery or safe disposal. Zinc is in growing demand all over the world. In India, a major amount of zinc is imported and therefore processing of zinc secondaries will assist in satisfying the gap between demand and supply to some extent. This report mainly focuses on the current practices and recent trends on the secondary processing of zinc. Attempts made by various laboratories to develop ecofriendly processes for the recovery of zinc from secondary raw materials are also described and discussed.

  17. 21 CFR 522.2112 - Sometribove zinc suspension.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 6 2011-04-01 2011-04-01 false Sometribove zinc suspension. 522.2112 Section 522....2112 Sometribove zinc suspension. (a) Specifications. Each single-dose syringe contains 500 milligrams (mg) sometribove zinc in a prolonged-release suspension. (b) Sponsor. See No. 000986 in § 510.600(c...

  18. Low-temperature solution-processed zinc oxide field effect transistor by blending zinc hydroxide and zinc oxide nanoparticle in aqueous solutions

    NASA Astrophysics Data System (ADS)

    Shin, Hyeonwoo; Kang, Chan-mo; Baek, Kyu-Ha; Kim, Jun Young; Do, Lee-Mi; Lee, Changhee

    2018-05-01

    We present a novel methods of fabricating low-temperature (180 °C), solution-processed zinc oxide (ZnO) transistors using a ZnO precursor that is blended with zinc hydroxide [Zn(OH)2] and zinc oxide hydrate (ZnO • H2O) in an ammonium solution. By using the proposed method, we successfully improved the electrical performance of the transistor in terms of the mobility (μ), on/off current ratio (I on/I off), sub-threshold swing (SS), and operational stability. Our new approach to forming a ZnO film was systematically compared with previously proposed methods. An atomic forced microscopic (AFM) image and an X-ray photoelectron spectroscopy (XPS) analysis showed that our method increases the ZnO crystallite size with less OH‑ impurities. Thus, we attribute the improved electrical performance to the better ZnO film formation using the blending methods.

  19. Ultrasonic measurements of thin zinc layers on concrete

    NASA Astrophysics Data System (ADS)

    Jansen, Henri; Brooks, Bill; Nguyen, Vinh; Koretsky, Milo

    2008-05-01

    In order to protect bridges at the coast from corrosion, a thin layer (approximately 0.5 mm) of zinc is sprayed on the concrete of the bridge. When this zinc layer is electrically connected to the reinforcing steel (rebar) and placed at a positive potential with respect to the rebar, oxidation is favored at the zinc layer and reduced at the rebar. The resulting protection of the rebar fails when the zinc layer delaminates from the concrete or when the zinc oxidation product layer becomes too thick. We have used ultrasonic detection to investigate the properties of the zinc layer. This method has been applied very successfully in the semiconductor industry. We present the details of the method and the expected response. Unfortunately, we are not able to measure changes in the zinc layer, because either the frequency we use (10-20 MHz) is too low, or scattering in the concrete is a dominant effect.

  20. Infantile zinc deficiency: Association with autism spectrum disorders

    PubMed Central

    Yasuda, Hiroshi; Yoshida, Kazuya; Yasuda, Yuichi; Tsutsui, Toyoharu

    2011-01-01

    Elucidation of the pathogenesis and effective treatment of autism spectrum disorders is one of the challenges today. In this study, we examine hair zinc concentrations for 1,967 children with autistic disorders (1,553 males and 414 females), and show considerable association with zinc deficiency. Histogram of hair zinc concentration was non-symmetric with tailing in lower range, and 584 subjects were found to have lower zinc concentrations than −2 standard deviation level of its reference range (86.3–193ppm). The incidence rate of zinc deficiency in infant group aged 0–3 year-old was estimated 43.5 % in male and 52.5 % in female. The lowest zinc concentration of 10.7 ppm was detected in a 2-year-old boy, corresponding to about 1/12 of the control mean level. These findings suggest that infantile zinc deficiency may epigenetically contribute to the pathogenesis of autism and nutritional approach may yield a novel hope for its treatment and prevention. PMID:22355646

  1. Zinc and its importance for human health: An integrative review

    PubMed Central

    Roohani, Nazanin; Hurrell, Richard; Kelishadi, Roya; Schulin, Rainer

    2013-01-01

    Since its first discovery in an Iranian male in 1961, zinc deficiency in humans is now known to be an important malnutrition problem world-wide. It is more prevalent in areas of high cereal and low animal food consumption. The diet may not necessarily be low in zinc, but its bio-availability plays a major role in its absorption. Phytic acid is the main known inhibitor of zinc. Compared to adults, infants, children, adolescents, pregnant, and lactating women have increased requirements for zinc and thus, are at increased risk of zinc depletion. Zinc deficiency during growth periods results in growth failure. Epidermal, gastrointestinal, central nervous, immune, skeletal, and reproductive systems are the organs most affected clinically by zinc deficiency. Clinical diagnosis of marginal Zn deficiency in humans remains problematic. So far, blood plasma/serum zinc concentration, dietary intake, and stunting prevalence are the best known indicators of zinc deficiency. Four main intervention strategies for combating zinc deficiency include dietary modification/diversification, supplementation, fortification, and bio-fortification. The choice of each method depends on the availability of resources, technical feasibility, target group, and social acceptance. In this paper, we provide a review on zinc biochemical and physiological functions, metabolism including, absorption, excretion, and homeostasis, zinc bio-availability (inhibitors and enhancers), human requirement, groups at high-risk, consequences and causes of zinc deficiency, evaluation of zinc status, and prevention strategies of zinc deficiency. PMID:23914218

  2. Bronze Alloy Development for Zinc Vapor Capture

    DOE PAGES

    Korinko, Paul S.

    2017-04-24

    After gamma-emitting 65Zinc was detected in a vacuum pumping system contained in a tritium glovebox, a series of experiments were undertaken to develop a method and material to trap zinc vapors in an area that is more suitable for preventing dose to workers. In this study, bronze alloys with 0–30% tin were prepared using a powder metallurgical process and exposed to three levels of zinc vapors. Furthermore, all of the alloys demonstrated acceptable zinc gettering capacity; however, low tin content bronzes are considered for further testing.

  3. Critical rate of electrolyte circulation for preventing zinc dendrite formation in a zinc-bromine redox flow battery

    NASA Astrophysics Data System (ADS)

    Yang, Hyeon Sun; Park, Jong Ho; Ra, Ho Won; Jin, Chang-Soo; Yang, Jung Hoon

    2016-09-01

    In a zinc-bromine redox flow battery, a nonaqueous and dense polybromide phase formed because of bromide oxidation in the positive electrolyte during charging. This formation led to complicated two-phase flow on the electrode surface. The polybromide and aqueous phases led to different kinetics of the Br/Br- redox reaction; poor mixing of the two phases caused uneven redox kinetics on the electrode surface. As the Br/Br- redox reaction was coupled with the zinc deposition reaction, the uneven redox reaction on the positive electrode was accompanied by nonuniform zinc deposition and zinc dendrite formation, which degraded battery stability. A single-flow cell was operated at varying electrolyte circulation rates and current densities. Zinc dendrite formation was observed after cell disassembly following charge-discharge testing. In addition, the flow behavior in the positive compartment was observed by using a transparent version of the cell. At low rate of electrolyte circulation, the polybromide phase clearly separated from the aqueous phase and accumulated at the bottom of the flow frame. In the corresponding area on the negative electrode, a large amount of zinc dendrites was observed after charge-discharge testing. Therefore, a minimum circulation rate should be considered to avoid poor mixing of the positive electrolyte.

  4. Zinc toxicology following particulate inhalation

    PubMed Central

    Cooper, Ross G.

    2008-01-01

    The current mini-review describes the toxic effects of zinc inhalation principally in the workplace and associated complications with breathing and respiration. The International Classification of Functioning, Disability and Health Criteria were used to specifically select articles. Most of the commercial production of zinc involves the galvanizing of iron and the manufacture of brass. The recommended daily allowance for adults is 15 mg zinc/day. Metal fume fever associated with inhalation of fumes of ZnO is characterized by fatigue, chills, fever, myalgias, cough, dyspnea, leukocytosis, thirst, metallic taste and salivation. ZnCl2 inhalation results in edema in the alveolar surface and the protein therein the lavage fluid is elevated. Particular pathological changes associated with zinc intoxication include: pale mucous membranes; jaundice; numerous Heinz bodies; and marked anemia. Adequate ambient air monitors for permissible exposure limits, excellent ventilation and extraction systems, and approved respirators are all important in providing adequate protection. PMID:20040991

  5. Measuring zinc in biological nanovesicles by multiple analytical approaches.

    PubMed

    Piacenza, Francesco; Biesemeier, Antje; Farina, Marco; Piva, Francesco; Jin, Xin; Pavoni, Eleonora; Nisi, Lorenzo; Cardelli, Maurizio; Costarelli, Laura; Giacconi, Robertina; Basso, Andrea; Pierpaoli, Elisa; Provinciali, Mauro; Hwang, James C M; Morini, Antonio; di Donato, Andrea; Malavolta, Marco

    2018-07-01

    Exosomes are nanovesicles known to mediate intercellular communication. Although it is established that zinc ions can act as intracellular signaling factors, the measurement of zinc in circulating nanovesicles has not yet been attempted. Providing evidence of the existence of this zinc fraction and methods for its measurement might be important to advance our knowledge of zinc status and its relevance in diseases. Exosomes from 0.5 ml of either fresh or frozen human plasma were isolated by differential centrifugation. A morphological and dimensional evaluation at the nanoscale level was performed by atomic force microscopy (AFM) and Transmission Electron Microscopy (TEM). Energy Dispersive X-Ray Microanalysis (EDX) revealed the elemental composition of exosomes and their respective total Zinc content on a quantitative basis. The zinc mole fraction (in at%) was correlated to the phosphorous mole fraction, which is indicative for exosomal membrane material. Both fresh (Zn/P 0.09 ± 0.01) and frozen exosomes (Zn/P 0.08 ± 0.02) had a significant zinc content, which increased up to 1.09 ± 0.12 for frozen exosomes when treated with increasing amounts of zinc (100-500 μM; each p < 0.05). Interestingly, after zinc addition, the Calcium mole fractions decreased accordingly suggesting a possible exchange by zinc. In order to estimate the intra-exosomal labile zinc content, an Imaging Flow Cytometry approach was developed by using the specific membrane permeable zinc-probe Fluozin-3AM. A labile zinc content of 0.59 ± 0.27 nM was calculated but it is likely that the measurement may be affected by purification and isolation conditions. This study suggests that circulating nano-vesicular-zinc can represent a newly discovered zinc fraction in the blood plasma whose functional and biological properties will have to be further investigated in future studies. Copyright © 2018 Elsevier GmbH. All rights reserved.

  6. Improved electrolyte for zinc-bromine flow batteries

    NASA Astrophysics Data System (ADS)

    Wu, M. C.; Zhao, T. S.; Wei, L.; Jiang, H. R.; Zhang, R. H.

    2018-04-01

    Conventional zinc bromide electrolytes offer low ionic conductivity and often trigger severe zinc dendrite growth in zinc-bromine flow batteries. Here we report an improved electrolyte modified with methanesulfonic acid, which not only improves the electrolyte conductivity but also ameliorates zinc dendrite. Experimental results also reveal that the kinetics and reversibility of Zn2+/Zn and Br2/Br- are improved in this modified electrolyte. Moreover, the battery's internal resistance is significantly reduced from 4.9 to 2.0 Ω cm2 after adding 1 M methanesulfonic acid, thus leading to an improved energy efficiency from 64% to 75% at a current density of 40 mA cm-2. More impressively, the battery is capable of delivering an energy efficiency of about 78% at a current density of as high as 80 mA cm-2 when the electrode is replaced by a thermally treated one. Additionally, zinc dendrite growth is found to be effectively suppressed in methanesulfonic acid supported media, which, as a result, enables the battery to be operated for 50 cycles without degradation, whereas the one without methanesulfonic acid suffers from significant decay after only 40 cycles, primarily due to severe zinc dendrite growth. These superior results indicate methanesulfonic acid is a promising supporting electrolyte for zinc-bromine flow batteries.

  7. Zinc and Regulation of Inflammatory Cytokines: Implications for Cardiometabolic Disease

    PubMed Central

    Foster, Meika; Samman, Samir

    2012-01-01

    In atherosclerosis and diabetes mellitus, the concomitant presence of low-grade systemic inflammation and mild zinc deficiency highlights a role for zinc nutrition in the management of chronic disease. This review aims to evaluate the literature that reports on the interactions of zinc and cytokines. In humans, inflammatory cytokines have been shown both to up- and down-regulate the expression of specific cellular zinc transporters in response to an increased demand for zinc in inflammatory conditions. The acute phase response includes a rapid decline in the plasma zinc concentration as a result of the redistribution of zinc into cellular compartments. Zinc deficiency influences the generation of cytokines, including IL-1β, IL-2, IL-6, and TNF-α, and in response to zinc supplementation plasma cytokines exhibit a dose-dependent response. The mechanism of action may reflect the ability of zinc to either induce or inhibit the activation of NF-κB. Confounders in understanding the zinc-cytokine relationship on the basis of in vitro experimentation include methodological issues such as the cell type and the means of activating cells in culture. Impaired zinc homeostasis and chronic inflammation feature prominently in a number of cardiometabolic diseases. Given the high prevalence of zinc deficiency and chronic disease globally, the interplay of zinc and inflammation warrants further examination. PMID:22852057

  8. Effects of Dietary Zinc Manipulation on Growth Performance, Zinc Status and Immune Response during Giardia lamblia Infection: A Study in CD-1 Mice

    PubMed Central

    Iñigo-Figueroa, Gemma; Méndez-Estrada, Rosa O.; Quihui-Cota, Luis; Velásquez-Contreras, Carlos A.; Garibay-Escobar, Adriana; Canett-Romero, Rafael; Astiazarán-García, Humberto

    2013-01-01

    Associations between Giardia lamblia infection and low serum concentrations of zinc have been reported in young children. Interestingly, relatively few studies have examined the effects of different dietary zinc levels on the parasite-infected host. The aims of this study were to compare the growth performance and zinc status in response to varying levels of dietary zinc and to measure the antibody-mediated response of mice during G. lamblia infection. Male CD-1 mice were fed using 1 of 4 experimental diets: adequate-zinc (ZnA), low-zinc (ZnL), high-zinc (ZnH) and supplemented-zinc (ZnS) diet containing 30, 10, 223 and 1383 mg Zn/kg respectively. After a 10 days feeding period, mice were inoculated orally with 5 × 106 G. lamblia trophozoites and were maintained on the assigned diet during the course of infection (30 days). Giardia-free mice fed ZnL diets were able to attain normal growth and antibody-mediated response. Giardia-infected mice fed ZnL and ZnA diets presented a significant growth retardation compared to non-infected controls. Zinc supplementation avoided this weight loss during G. lamblia infection and up-regulated the host’s humoral immune response by improving the production of specific antibodies. Clinical outcomes of zinc supplementation during giardiasis included significant weight gain, higher anti-G. lamblia IgG antibodies and improved serum zinc levels despite the ongoing infection. A maximum growth rate and antibody-mediated response were attained in mice fed ZnH diet. No further increases in body weight, zinc status and humoral immune capacity were noted by feeding higher zinc levels (ZnS) than the ZnH diet. These findings probably reflect biological effect of zinc that could be of public health importance in endemic areas of infection. PMID:24002196

  9. Zinc status in South Asian populations--an update.

    PubMed

    Akhtar, Saeed

    2013-06-01

    This article attempts to highlight the prevalence of zinc deficiency and its health and economic consequences in South Asian developing countries and to shed light on possible approaches to combating zinc deficiency. A computer-based search was performed on PubMed, Google, and ScienceDirect.com to retrieve relevant scientific literature published between 2000 and 2012. The search yielded 194 articles, of which 71 were culled. Studies were further screened on the basis of population groups, age and sex, pregnancy, and lactation. The most relevant articles were included in the review. Cutoffs for serum zinc concentration defined for zinc deficiency were 65 microg/dL for males and females aged < 10 years, 66 microg/dL for non-pregnant females, and 70 microg/dL for males aged > or = 10 years. Population segments from rural and urban areas of South Asian developing countries were included in the analysis. They comprised pregnant and lactating women, preschool and school children. The analysis reveals that zinc deficiency is high among children, pregnant and lactating women in India, Pakistan, Bangladesh, Sri Lanka, and Nepal. Diarrhoea has been established as a leading cause to intensify zinc deficiency in Bangladesh. Little has been done in Sri Lanka and Nepal to estimate the prevalence of zinc deficiency precisely. A substantial population segment of the South Asian developing countries is predisposed to zinc deficiency which is further provoked by increased requirements for zinc under certain physiological conditions. Supplementation, fortification, and dietary diversification are the most viable strategies to enhancing zinc status among various population groups.

  10. Comparative studies on acid leaching of zinc waste materials

    NASA Astrophysics Data System (ADS)

    Rudnik, Ewa; Włoch, Grzegorz; Szatan, Leszek

    2017-11-01

    Three industrial waste materials were characterized in terms of their elemental and phase compositions, leaching behaviour in 10% sulfuric acid solution as well as leaching thermal effects. Slag from melting of mixed metallic scrap contained about 50% Zn and 10% Pb. It consisted mainly of various oxides and oxy-chlorides of metals. Zinc spray metallizing dust contained about 77% Zn in form of zinc and/or zinc-iron oxides, zinc metal and Zn-Fe intermetallic. Zinc ash from hot dip galvanizing was a mixture of zinc oxide, metallic zinc and zinc hydroxide chloride and contained about 80% Zn. Dissolution efficiency of zinc from the first material was 80% (independently on the solid to liquid ratio, 50-150 kg/m3), while decrease of the efficacy from 80% to 60% with increased solid to liquid ratio for the two remaining materials was observed. Both increase in the temperature (20 °C to 35 °C) and agitation rate (300 rpm to 900 rpm) did not improve seriously the leaching results. In all cases, transfer of zinc ions to the leachate was accompanied by different levels of solution contamination, depending on the type of the waste. Leaching of the materials was exothermic with the similar reaction heats for two high oxide-type products (slag, zinc ash) and higher values for the spray metallizing dust.

  11. Electrodeposition of zinc hydroxysulfate nanosheets and reduction to zinc metal microdendrites on polypyrrole films.

    PubMed

    Andreoli, Enrico; Rooney, Denise A; Redington, Wynette; Gunning, Robert; Breslin, Carmel B

    2012-01-01

    Nanothin sheets made of zinc sulfate hydroxide hydrate, ZnSO4[Zn(OH)2]3 x 5H2O, are easily and quickly prepared using an innovative electrochemical route onto polypyrrole-polystyrene sulfonate (PPy-PSS) films. The sheets are characterized using a range of experimental techniques. The deposits are formed on the film surface with instantaneous nucleation to grow into a network of entangled nanosheets. The effect of the experimental conditions on the deposition is reported. Interestingly, the formation of the nanosheets is observed on PPy-PSS films only, and not on films doped with other sulfate/sulfonate dopants. The zinc nanosheets can be easily electrochemically reduced to metallic zinc microdentrites.

  12. Implication of zinc excess on soil health.

    PubMed

    Wyszkowska, Jadwiga; Boros-Lajszner, Edyta; Borowik, Agata; Baćmaga, Małgorzata; Kucharski, Jan; Tomkiel, Monika

    2016-01-01

    This study was undertaken to evaluate zinc's influence on the resistance of organotrophic bacteria, actinomyces, fungi, dehydrogenases, catalase and urease. The experiment was conducted in a greenhouse of the University of Warmia and Mazury (UWM) in Olsztyn, Poland. Plastic pots were filled with 3 kg of sandy loam with pHKCl - 7.0 each. The experimental variables were: zinc applied to soil at six doses: 100, 300, 600, 1,200, 2,400 and 4,800 mg of Zn(2+) kg(-1) in the form of ZnCl2 (zinc chloride), and species of plant: oat (Avena sativa L.) cv. Chwat and white mustard (Sinapis alba) cv. Rota. Soil without the addition of zinc served as the control. During the growing season, soil samples were subjected to microbiological analyses on experimental days 25 and 50 to determine the abundance of organotrophic bacteria, actinomyces and fungi, and the activity of dehydrogenases, catalase and urease, which provided a basis for determining the soil resistance index (RS). The physicochemical properties of soil were determined after harvest. The results of this study indicate that excessive concentrations of zinc have an adverse impact on microbial growth and the activity of soil enzymes. The resistance of organotrophic bacteria, actinomyces, fungi, dehydrogenases, catalase and urease decreased with an increase in the degree of soil contamination with zinc. Dehydrogenases were most sensitive and urease was least sensitive to soil contamination with zinc. Zinc also exerted an adverse influence on the physicochemical properties of soil and plant development. The growth of oat and white mustard plants was almost completely inhibited in response to the highest zinc doses of 2,400 and 4,800 mg Zn(2+) kg(-1).

  13. Hemimorphite Ores: A Review of Processing Technologies for Zinc Extraction

    NASA Astrophysics Data System (ADS)

    Chen, Ailiang; Li, Mengchun; Qian, Zhen; Ma, Yutian; Che, Jianyong; Ma, Yalin

    2016-10-01

    With the gradual depletion of zinc sulfide ores, exploration of zinc oxide ores is becoming more and more important. Hemimorphite is a major zinc oxide ore, attracting much attention in the field of zinc metallurgy although it is not the major zinc mineral. This paper presents a critical review of the treatment for extraction of zinc with emphasis on flotation, pyrometallurgical and hydrometallurgical methods based on the properties of hemimorphite. The three-dimensional framework structure of hemimorphite with complex linkage of its structural units lead to difficult desilicification before extracting zinc in the many metallurgical technologies. It is found that the flotation method is generally effective in enriching zinc minerals from hemimorphite ores into a high-grade concentrate for recovery of zinc. Pure zinc can be produced from hemimorphite or/and willemite with a reducing reagent, like methane or carbon. Leaching reagents, such as acid and alkali, can break the complex structure of hemimorphite to release zinc in the leached solution without generation of silica gel in the hydrometallurgical process. For optimal zinc extraction, combing flotation with pyrometallurgical or hydrometallurgical methods may be required.

  14. Influence of structural and surface properties of whey-derived peptides on zinc-chelating capacity, and in vitro gastric stability and bioaccessibility of the zinc-peptide complexes.

    PubMed

    Udechukwu, M Chinonye; Downey, Brianna; Udenigwe, Chibuike C

    2018-02-01

    Gastrointestinal stability of zinc-peptide complexes is essential for zinc delivery. As peptide surface charge can influence their metal complex stability, we evaluated the zinc-chelating capacity and stability of zinc complexes of whey protein hydrolysates (WPH), produced with Everlase (WPH-Ever; ζ-potential, -39mV) and papain (WPH-Pap; ζ-potential, -7mV), during simulated digestion. WPH-Ever had lower amount of zinc-binding amino acids but showed higher zinc-chelating capacity than WPH-Pap. This is attributable to the highly anionic surface charge of WPH-Ever for electrostatic interaction with zinc. Release of zinc during peptic digestion was lower for WPH-Ever-zinc, and over 50% of zinc remained bound in both peptide complexes after peptic-pancreatic digestion. Fourier transform infrared spectroscopy suggests the involvement of carboxylate ion, and sidechain carbon-oxygen of aspartate/glutamate and serine/threonine in zinc-peptide complexation. The findings indicate that strong zinc chelation can promote gastric stability and impede intestinal release, for peptides intended for use as dietary zinc carriers. Copyright © 2017 Elsevier Ltd. All rights reserved.

  15. Aircraft Disinsection: A Guide for Military and Civilian Air Carriers (Desinsectisation des aeronefs: Un guide a l’intention des responsables des transports aeriens civils et militaires)

    DTIC Science & Technology

    1996-04-01

    regulations. - Ceratitis capitata (Mediterranean fruit fly). Quarantine regulations generally reduce - Rhagoletis pomonella (Apple maggot). the chances of a...d’insectes nuisibles dans un pays, en 6vitant des risques pour la sant6 des 6quipages, pour la s~curit6 de 1’a~ronef et pour l’industrie. Ce rapport examine 1...diffrrents officiels responsables de la r~glementation des insectes nuisibles introduits, de l’inscription des pesticides et de leur utilisation en

  16. The Nuclear Receptor HIZR-1 Uses Zinc as a Ligand to Mediate Homeostasis in Response to High Zinc

    PubMed Central

    Warnhoff, Kurt; Roh, Hyun C.; Kocsisova, Zuzana; Tan, Chieh-Hsiang; Morrison, Andrew; Croswell, Damari; Schneider, Daniel L.; Kornfeld, Kerry

    2017-01-01

    Nuclear receptors were originally defined as endocrine sensors in humans, leading to the identification of the nuclear receptor superfamily. Despite intensive efforts, most nuclear receptors have no known ligand, suggesting new ligand classes remain to be discovered. Furthermore, nuclear receptors are encoded in the genomes of primitive organisms that lack endocrine signaling, suggesting the primordial function may have been environmental sensing. Here we describe a novel Caenorhabditis elegans nuclear receptor, HIZR-1, that is a high zinc sensor in an animal and the master regulator of high zinc homeostasis. The essential micronutrient zinc acts as a HIZR-1 ligand, and activated HIZR-1 increases transcription of genes that promote zinc efflux and storage. The results identify zinc as the first inorganic molecule to function as a physiological ligand for a nuclear receptor and direct environmental sensing as a novel function of nuclear receptors. PMID:28095401

  17. Reduction of zinc emissions from buildings; the policy of Amsterdam.

    PubMed

    Gouman, E

    2004-01-01

    In Amsterdam zinc coming from the roofs and gutters of the buildings accounts for about 50% of the zinc emissions into the surface water (i.e. canals and rivers). This causes water and sediment pollution. Dumping strongly polluted sediment costs ten times more then dumping less polluted mud. Therefore the City of Amsterdam has developed a policy for reducing the zinc emissions from buildings based on the current environmental legislation and the current national targets for surface water quality. Zinc roofs on new and renovated buildings are not permitted. Run off water from zinc roofs of existing buildings is allowed to contain a maximum of 200 microg/l zinc. For the zinc gutters of houses, Amsterdam will promote measures to reduce zinc emissions. To investigate the feasibility of measures, research has been carried out on the zinc emissions of gutters and the effect of covering gutters with an impermeable foil. This research shows clearly that covering zinc gutters with EPDM foil reduces the zinc emissions by 90% from 8.5 to 0.88 gram per square metre per year including the atmospheric deposition.

  18. The influence of inflammation on plasma zinc concentration in apparently healthy, HIV+ Kenyan adults and zinc responses after a multi-micronutrient supplement.

    PubMed

    Mburu, A S W; Thurnham, D I; Mwaniki, D L; Muniu, E M; Alumasa, F M

    2010-05-01

    Plasma zinc is an important biomarker of zinc status, but the concentration is depressed by inflammation. Apparently healthy adults, who tested positive twice for human immunodeficiency virus (HIV) but who had not reached stage IV or clinical AIDS, were randomly allocated to receive a food supplement (n=17 and 21) or the food plus a micronutrient capsule (MN; n=10 men and n=33 women) containing 15 mg zinc/day. We used the inflammation biomarkers, C-reactive protein (CRP) and alpha1-acid glycoprotein (AGP), to identify subjects with and without inflammation and determine the effect of inflammation on the response of plasma zinc concentrations to the MN and food supplements. There were no differences between men and women either in plasma zinc or in the responses to the supplements and their data were combined. Plasma zinc was lower in those with inflammation than without. Repeated measures analysis of variance (ANOVA) showed that inflammation blocked increases in plasma zinc, and there was an approximate 10% increase in plasma zinc concentration in response to the MN supplement (P=0.023) in those without inflammation. Subgroup analysis showed mean changes in plasma zinc of 0.95 and -0.83 micromol/l (P=0.031) in response to the MN and food treatments, respectively, in those without inflammation at both time points. Inflammation seems to block any increase in plasma zinc after MN supplement and it is important to identify those without inflammation to determine the effectiveness of a zinc supplementation program.

  19. Plasma zinc's alter ego is a low-molecular-weight humoral factor.

    PubMed

    Ou, Ou; Allen-Redpath, Keith; Urgast, Dagmar; Gordon, Margaret-Jane; Campbell, Gill; Feldmann, Jörg; Nixon, Graeme F; Mayer, Claus-Dieter; Kwun, In-Sook; Beattie, John H

    2013-09-01

    Mild dietary zinc deprivation in humans and rodents has little effect on blood plasma zinc levels, and yet cellular consequences of zinc depletion can be detected in vascular and other tissues. We proposed that a zinc-regulated humoral factor might mediate the effects of zinc deprivation. Using a novel approach, primary rat vascular smooth muscle cells (VSMCs) were treated with plasma from zinc-deficient (<1 mg Zn/kg) or zinc-adequate (35 mg Zn/kg, pair-fed) adult male rats, and zinc levels were manipulated to distinguish direct and indirect effects of plasma zinc. Gene expression changes were analyzed by microarray and qPCR, and incubation of VSMCs with blood plasma from zinc-deficient rats strongly changed the expression of >2500 genes, compared to incubation of cells with zinc-adequate rat plasma. We demonstrated that this effect was caused by a low-molecular-weight (∼2-kDa) zinc-regulated humoral factor but that changes in gene expression were mostly reversed by adding zinc back to zinc-deficient plasma. Strongly regulated genes were overrepresented in pathways associated with immune function and development. We conclude that zinc deficiency induces the production of a low-molecular-weight humoral factor whose influence on VSMC gene expression is blocked by plasma zinc. This factor is therefore under dual control by zinc.

  20. 21 CFR 73.2995 - Luminescent zinc sulfide.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 1 2013-04-01 2013-04-01 false Luminescent zinc sulfide. 73.2995 Section 73.2995 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL LISTING OF COLOR ADDITIVES EXEMPT FROM CERTIFICATION Cosmetics § 73.2995 Luminescent zinc sulfide. (a) Identity. The color additive luminescent zinc sulfide...

  1. 21 CFR 73.2995 - Luminescent zinc sulfide.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 1 2012-04-01 2012-04-01 false Luminescent zinc sulfide. 73.2995 Section 73.2995 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL LISTING OF COLOR ADDITIVES EXEMPT FROM CERTIFICATION Cosmetics § 73.2995 Luminescent zinc sulfide. (a) Identity. The color additive luminescent zinc sulfide...

  2. Role of zinc in chronic gastritis.

    PubMed

    Marjanović, Ksenija; Dovhanj, Jasna; Kljaić, Ksenija; Sakić, Katarina; Kondza, Goran; Tadzić, Refmir; Vcev, Aleksandar

    2010-06-01

    Oxidative stress occurs in inflammation of gastric mucosa. The role of zinc in modulating oxidative stress has recently been recognized. Zn deficiency results in an increased sensitivity to oxidative stress and have a higher risk of musoca damage in inflammation. The aim of this study was to determine wheather chronic inflammation affects on the concentration of Zn2+ ions in gastric mucosa of patients with chronic gastritis. Forthy-three patients with chronic gastitis were enrolled. Patients were endoscoped. Histology and scoring of gastritis was performed following the guidelines of the updated Sydney system. Endoscopic finding of mucosa were scored according to a Lanza scoring system. The diagnosis of Helicobacter pylori (H. pylori) infection, histopathologic changes, intensity of inflammation and zinc concentration were determined from biopsies of gastric mucosa. The atomic absorption spectrophotometer was used to determine tissue concentrations of zinc. Twenty of 43 patients with chronic gastritis were uninfected by H. pylori. There was no statistically significant difference in tissue concentrations of zinc between H. pylori-positive and H. pylori-negative patients. From those infected patients 53.3% had chronic active gastritis. There was no statistically significant difference in tissue concentrations of zinc between patients with chronic active gastritis and patients with chronic inactive gastritis (p = 0.966). Zn in antrum showed positive correlation with density of H. pylori in antrum (Spearman' rho = 0.481, p = 0.020), negative correlation with density of H. pylori in corpus (Spearman' rho = -0.492, p = 0.017) and with zinc in corpus (Spearman' rho = 0.631, p =0.001). Tissue concentration of zinc was not affected by chronic inflammation of gastric mucosa in patients with chronic gastritis.

  3. Release of iron, zinc, and lead from common iron construction bars and zinc metallic bars in water solutions and meals.

    PubMed

    Lechtig, Aarón; Lòpez de Romaña, Daniel; Boy, Erick; Vargas, Alejandro; Rosas del Portal, Mauricio; Huaylinos, María Luisa

    2007-12-01

    The use of iron pots has decreased the prevalence of anemia. To investigate the release of iron, zinc, and lead from metallic iron and zinc bars incubated in water and in meals. Iron, zinc, and lead concentrations were measured at different incubation conditions in water and in meals. The iron concentration in water was 1.26 mg/L after incubation with one iron bar at pH 7 and 100 degrees C for 20 minutes and in meals was 0.97 mg per 100 g of wet meals, rich in phytate, cooking at 100 degrees C during 20 minutes. The maximum contents were 7720 mg/L of iron and 1826 mg/L of zinc in vinegar at pH 3 and 20 degrees C after 90 and 32 days, respectively. Lead was released from the bars, but at concentrations well below the upper tolerable limits. In outreach populations, the use of iron and zinc metallic bars in water and meals could contribute to sustainable, very low-cost prevention of iron and zinc deficiencies, and home-fortified vinegar could be used for treatment of both deficiencies. Field trials should be performed to determine the impact that the use of iron and zinc metallic bars in water and meals might have on the iron and zinc status of population groups.

  4. Effect of zinc supplementation on serum zinc concentration and T cell proliferation in nursing home elderly:A randomized double-blind placebo-controlled trial

    USDA-ARS?s Scientific Manuscript database

    Background: Zinc is essential for the regulation of immune response. T cell function declines with age. Zinc supplementation has the potential to improve serum zinc concentrations and immunity of nursing home elderly with low serum zinc concentration. Objective: We aimed to determine the effect of ...

  5. Zinc release from Schaffer collaterals and its significance.

    PubMed

    Takeda, Atsushi; Nakajima, Satoko; Fuke, Sayuri; Sakurada, Naomi; Minami, Akira; Oku, Naoto

    2006-02-15

    On the basis of the evidence that approximately 45% of Schaffer collateral boutons are zinc-positive, zinc release from Schaffer collaterals and its action were examined in hippocampal slices. When zinc release from Schaffer collaterals was examined using ZnAF-2, a membrane-impermeable zinc indicator, ZnAF-2 signal in the stratum radiatum of the CA1 was increased by tetanic stimuli at 100 Hz for 1s, suggesting that zinc is released from Schaffer collaterals in a calcium- and impulse-dependent manner. An in vivo microdialysis experiment indicated that the perfusion with 10 microM zinc significantly decreases extracellular glutamate concentration in the CA1. When tetanic stimuli at 100 Hz for 5s were delivered to the dentate granule cells, the increase in calcium signal in the stratum radiatum of the CA1, as well as in the stratum lucidum of the CA3, was attenuated by addition of 10 microM zinc, while enhanced by addition of 1mM CaEDTA, a membrane-impermeable zinc chelator. The increase in calcium signal in the CA1, in which Schaffer collateral synapses exist, during delivery of tetanic stimuli at 100 Hz for 1s to the Schaffer collateral-commissural pathway was also significantly enhanced by addition of 1mM CaEDTA. These results suggest that zinc released from Schaffer collaterals suppressively modulates presynaptic and postsynaptic calcium signaling in the CA1, followed by the suppression of glutamate release.

  6. Preparation of ionic membranes for zinc/bromine storage batteries

    NASA Astrophysics Data System (ADS)

    Assink, R. A.; Arnold, C., Jr.

    Zinc/bromine flow batteries are being developed for vehicular and utility load leveling applications. During charge, an aqueous zinc bromide salt is electrolyzed to zinc metal and molecular bromine. During discharge, the zinc and bromine react to again form the zinc bromide salt. One serious disadvantage of the microporous separators presently used in the zinc/bromine battery is that modest amounts of bromine and negatively charged bromine moieties permeate through these materials and react with the zinc anode. This results in partial self-discharge of the battery and low coulombic efficiencies. Our approach to this problem is to impregnate the microporous separators with a soluble cationic polyelectrolyte. In laboratory screening tests a sulfonated polysulfone resin and fully fluorinated sulfonic acid polymer substantially reduced bromine permeation with only modest increases in the area resistance.

  7. Zinc Nucleation and Growth in Microgravity

    NASA Technical Reports Server (NTRS)

    Michael, B. Patrick; Nuth, J. A., III; Lilleleht, L. U.; Vondrak, Richard R. (Technical Monitor)

    2000-01-01

    We report our experiences with zinc nucleation in a microgravity environment aboard NASA's Reduced Gravity Research Facility. Zinc vapor is produced by a heater in a vacuum chamber containing argon gas. Nucleation is induced by cooling and its onset is easily detected visually by the appearance of a cloud of solid, at least partially crystalline zinc particles. Size distribution of these particles is monitored in situ by photon correlation spectroscopy. Samples of particles are also extracted for later analysis by SEM. The initially rapid increase in particle size is followed by a slower period of growth. We apply Scaled Nucleation Theory to our data and find that the derived critical temperature of zinc, the critical cluster size at nucleation, and the surface tension values are all in reasonably good agreement with their accepted literature values.

  8. Crosstalk between Zinc Status and Giardia Infection: A New Approach

    PubMed Central

    Astiazarán-García, Humberto; Iñigo-Figueroa, Gemma; Quihui-Cota, Luis; Anduro-Corona, Iván

    2015-01-01

    Zinc supplementation has been shown to reduce the incidence and prevalence of diarrhea; however, its anti-diarrheal effect remains only partially understood. There is now growing evidence that zinc can have pathogen-specific protective effects. Giardiasis is a common yet neglected cause of acute-chronic diarrheal illness worldwide which causes disturbances in zinc metabolism of infected children, representing a risk factor for zinc deficiency. How zinc metabolism is compromised by Giardia is not well understood; zinc status could be altered by intestinal malabsorption, organ redistribution or host-pathogen competition. The potential metal-binding properties of Giardia suggest unusual ways that the parasite may interact with its host. Zinc supplementation was recently found to reduce the rate of diarrhea caused by Giardia in children and to upregulate humoral immune response in Giardia-infected mice; in vitro and in vivo, zinc-salts enhanced the activity of bacitracin in a zinc-dose-dependent way, and this was not due to zinc toxicity. These findings reflect biological effect of zinc that may impact significantly public health in endemic areas of infection. In this paper, we shall explore one direction of this complex interaction, discussing recent information regarding zinc status and its possible contribution to the outcome of the encounter between the host and Giardia. PMID:26046395

  9. Zinc and its transporters, pancreatic beta cells, and insulin metabolism

    USDA-ARS?s Scientific Manuscript database

    Zinc is an essential trace metal for life. Two families of zinc transporters, SLC30A (ZnT) and SLC39A (ZIP) are required for maintaining cellular zinc homeostasis. ZnTs function to decrease cytoplasmic zinc concentrations whereas ZIPs do the opposite. Expression of zinc transporters can be tissue/ce...

  10. Cartographie des disques

    NASA Astrophysics Data System (ADS)

    Hameury, Jean-Marie

    2001-01-01

    Two techniques are frequently used to produce images of the accretion disc in an eclipsing binary: eclipse mapping and Doppler tomography. From the light curve, one can deduce the radial distribution of the effective temperature, assuming axial symmetry. On the other hand, from the variation of the line profile one can reconstruct an image in the velocity space, which can be converted into a real image if one knows the kinematics of the system. Deux techniques sont couramment utilisées pour obtenir des images des disques dans les systèmes binaires à éclipses. En utilisant la courbe de lumière, on peut remonter à la distribution radiale de la brillance de surface, en supposant que celle-ci a une symètrie axiale. D'autre part, les profils de raies renseignent sur la distribution de vitesse des régions émissives leur variation temporelle permet de réaliser une image dans l'espace des vitesses, que l'on peut ensuite transformer en carte dans l'espace (x,y) si on connaît la cinématique du système.

  11. Hair Zinc: an Index for Zinc Status in Under-Five Children from Low-Income Communities in Kanam Area of North-Central Nigeria.

    PubMed

    Jaryum, Kiri H; Okoye, Zebulon Sunday C; Stoecker, Barbara

    2018-06-01

    Nutritional deficiencies of trace elements are among the top ten causes of death in Sub Saharan Africa. In Kanam Local Government Area of Nigeria, the problem is compounded by high levels of poverty and illiteracy. Abnormally low hair zinc levels are important, sensitive diagnostic biochemical indices of Zinc deficiency. The purpose of this study is to assess the zinc status of children less than 5 years in Kanam local government area, north-central Nigeria, by measuring the zinc level in hair samples collected from 44 under-5 children across the area. A household survey was made to assess the pattern and frequency of consumption of zinc-rich foods which was done by means of questionnaire. Hair samples were analysed for zinc content by the inductively coupled plasma-mass spectrophotometry (ICP-MS). The data were analysed statistically using the Student's t test, z test, and Pearson correlation, while questionnaire-captured data were analysed by simple arithmetic. The results of the analyses showed that the average hair zinc level was 74.35 ± 48.05 μg/g. This was below the normal range of 130-140 μg/g, for children less than 5 years. Based on the results, 86.36% have hair zinc level below the lower limit of the normal range of 130 μg/g. Between the gender, boys have higher hair zinc content than girls. Data from the questionnaire showed that 53.45% of the population studied have poor/inadequate intake of zinc-rich foods of animal origin, a dietary behaviour reported to predispose to micronutrient deficiency, including zinc.

  12. Recent advances in knowledge of zinc nutrition and human health.

    PubMed

    Hess, Sonja Y; Lönnerdal, Bo; Hotz, Christine; Rivera, Juan A; Brown, Kenneth H

    2009-03-01

    Zinc deficiency increases the risk and severity of a variety of infections, restricts physical growth, and affects specific outcomes of pregnancy. Global recognition of the importance of zinc nutrition in public health has expanded dramatically in recent years, and more experience has accumulated on the design and implementation of zinc intervention programs. Therefore, the Steering Committee of the International Zinc Nutrition Consultative Group (IZiNCG) completed a second IZiNCG technical document that reexamines the latest information on the intervention strategies that have been developed to enhance zinc nutrition and control zinc deficiency. In particular, the document reviews the current evidence regarding preventive zinc supplementation and the role of zinc as adjunctive therapy for selected infections, zinc fortification, and dietary diversification or modification strategies, including the promotion and protection of breastfeeding and biofortification. The purposes of this introductory paper are to summarize new guidelines on the assessment of population zinc status, as recommended by the World Health Organization (WHO), the United Nations Children's Fund (UNICEF), the International Atomic Energy Agency (IAEA), and IZiNCG, and to provide an overview on several new advances in zinc metabolism. The following papers will then review the intervention strategies individually.

  13. Dietary Zinc Deficiency Affects Blood Linoleic Acid: Dihomo-γ-linolenic Acid (LA:DGLA) Ratio; a Sensitive Physiological Marker of Zinc Status in Vivo (Gallus gallus)

    PubMed Central

    Reed, Spenser; Qin, Xia; Ran-Ressler, Rinat; Brenna, James Thomas; Glahn, Raymond P.; Tako, Elad

    2014-01-01

    Zinc is a vital micronutrient used for over 300 enzymatic reactions and multiple biochemical and structural processes in the body. To date, sensitive and specific biological markers of zinc status are still needed. The aim of this study was to evaluate Gallus gallus as an in vivo model in the context of assessing the sensitivity of a previously unexplored potential zinc biomarker, the erythrocyte linoleic acid: dihomo-γ-linolenic acid (LA:DGLA) ratio. Diets identical in composition were formulated and two groups of birds (n = 12) were randomly separated upon hatching into two diets, Zn(+) (zinc adequate control, 42.3 μg/g zinc), and Zn(−) (zinc deficient, 2.5 μg/g zinc). Dietary zinc intake, body weight, serum zinc, and the erythrocyte fatty acid profile were measured weekly. At the conclusion of the study, tissues were collected for gene expression analysis. Body weight, feed consumption, zinc intake, and serum zinc were higher in the Zn(+) control versus Zn(−) group (p < 0.05). Hepatic TNF-α, IL-1β, and IL-6 gene expression were higher in the Zn(+) control group (p < 0.05), and hepatic Δ6 desaturase was significantly higher in the Zn(+) group (p < 0.001). The LA:DGLA ratio was significantly elevated in the Zn(−) group compared to the Zn(+) group (22.6 ± 0.5 and 18.5 ± 0.5, % w/w, respectively, p < 0.001). This study suggests erythrocyte LA:DGLA is able to differentiate zinc status between zinc adequate and zinc deficient birds, and may be a sensitive biomarker to assess dietary zinc manipulation. PMID:24658588

  14. Mining Genomes of Marine Cyanobacteria for Elements of Zinc Homeostasis

    PubMed Central

    Barnett, James P.; Millard, Andrew; Ksibe, Amira Z.; Scanlan, David J.; Schmid, Ralf; Blindauer, Claudia Andrea

    2012-01-01

    Zinc is a recognized essential element for the majority of organisms, and is indispensable for the correct function of hundreds of enzymes and thousands of regulatory proteins. In aquatic photoautotrophs including cyanobacteria, zinc is thought to be required for carbonic anhydrase and alkaline phosphatase, although there is evidence that at least some carbonic anhydrases can be cambialistic, i.e., are able to acquire in vivo and function with different metal cofactors such as Co2+ and Cd2+. Given the global importance of marine phytoplankton, zinc availability in the oceans is likely to have an impact on both carbon and phosphorus cycles. Zinc concentrations in seawater vary over several orders of magnitude, and in the open oceans adopt a nutrient-like profile. Most studies on zinc handling by cyanobacteria have focused on freshwater strains and zinc toxicity; much less information is available on marine strains and zinc limitation. Several systems for zinc homeostasis have been characterized in the freshwater species Synechococcus sp. PCC 7942 and Synechocystis sp. PCC 6803, but little is known about zinc requirements or zinc handling by marine species. Comparative metallo-genomics has begun to explore not only the putative zinc proteome, but also specific protein families predicted to have an involvement in zinc homeostasis, including sensors for excess and limitation (SmtB and its homologs as well as Zur), uptake systems (ZnuABC), putative intracellular zinc chaperones (COG0523) and metallothioneins (BmtA), and efflux pumps (ZiaA and its homologs). PMID:22514551

  15. Zinc allocation and re-allocation in rice.

    PubMed

    Stomph, Tjeerd Jan; Jiang, Wen; Van Der Putten, Peter E L; Struik, Paul C

    2014-01-01

    Agronomy and breeding actively search for options to enhance cereal grain Zn density. Quantifying internal (re-)allocation of Zn as affected by soil and crop management or genotype is crucial. We present experiments supporting the development of a conceptual model of whole plant Zn allocation and re-allocation in rice. Two solution culture experiments using (70)Zn applications at different times during crop development and an experiment on within-grain distribution of Zn are reported. In addition, results from two earlier published experiments are re-analyzed and re-interpreted. A budget analysis showed that plant zinc accumulation during grain filling was larger than zinc allocation to the grains. Isotope data showed that zinc taken up during grain filling was only partly transported directly to the grains and partly allocated to the leaves. Zinc taken up during grain filling and allocated to the leaves replaced zinc re-allocated from leaves to grains. Within the grains, no major transport barrier was observed between vascular tissue and endosperm. At low tissue Zn concentrations, rice plants maintained concentrations of about 20 mg Zn kg(-1) dry matter in leaf blades and reproductive tissues, but let Zn concentrations in stems, sheath, and roots drop below this level. When plant zinc concentrations increased, Zn levels in leaf blades and reproductive tissues only showed a moderate increase while Zn levels in stems, roots, and sheaths increased much more and in that order. In rice, the major barrier to enhanced zinc allocation towards grains is between stem and reproductive tissues. Enhancing root to shoot transfer will not contribute proportionally to grain zinc enhancement.

  16. Zinc allocation and re-allocation in rice

    PubMed Central

    Stomph, Tjeerd Jan; Jiang, Wen; Van Der Putten, Peter E. L.; Struik, Paul C.

    2014-01-01

    Aims: Agronomy and breeding actively search for options to enhance cereal grain Zn density. Quantifying internal (re-)allocation of Zn as affected by soil and crop management or genotype is crucial. We present experiments supporting the development of a conceptual model of whole plant Zn allocation and re-allocation in rice. Methods: Two solution culture experiments using 70Zn applications at different times during crop development and an experiment on within-grain distribution of Zn are reported. In addition, results from two earlier published experiments are re-analyzed and re-interpreted. Results: A budget analysis showed that plant zinc accumulation during grain filling was larger than zinc allocation to the grains. Isotope data showed that zinc taken up during grain filling was only partly transported directly to the grains and partly allocated to the leaves. Zinc taken up during grain filling and allocated to the leaves replaced zinc re-allocated from leaves to grains. Within the grains, no major transport barrier was observed between vascular tissue and endosperm. At low tissue Zn concentrations, rice plants maintained concentrations of about 20 mg Zn kg−1 dry matter in leaf blades and reproductive tissues, but let Zn concentrations in stems, sheath, and roots drop below this level. When plant zinc concentrations increased, Zn levels in leaf blades and reproductive tissues only showed a moderate increase while Zn levels in stems, roots, and sheaths increased much more and in that order. Conclusions: In rice, the major barrier to enhanced zinc allocation towards grains is between stem and reproductive tissues. Enhancing root to shoot transfer will not contribute proportionally to grain zinc enhancement. PMID:24478788

  17. The relevance of the colon to zinc nutrition

    USDA-ARS?s Scientific Manuscript database

    Globally, zinc deficiency is widespread, despite decades of research highlighting its negative effects on health, and in particular upon child health in low-income countries. Apart from inadequate dietary intake of bioavailable zinc, other significant contributors to zinc deficiency include the exce...

  18. Scale-up synthesis of zinc borate from the reaction of zinc oxide and boric acid in aqueous medium

    NASA Astrophysics Data System (ADS)

    Kılınç, Mert; Çakal, Gaye Ö.; Yeşil, Sertan; Bayram, Göknur; Eroğlu, İnci; Özkar, Saim

    2010-11-01

    Synthesis of zinc borate was conducted in a laboratory and a pilot scale batch reactor to see the influence of process variables on the reaction parameters and the final product, 2ZnO·3B 2O 3·3.5H 2O. Effects of stirring speed, presence of baffles, amount of seed, particle size and purity of zinc oxide, and mole ratio of H 3BO 3:ZnO on the zinc borate formation reaction were examined at a constant temperature of 85 °C in a laboratory (4 L) and a pilot scale (85 L) reactor. Products obtained from the reaction in both reactors were characterized by chemical analysis, X-ray diffraction, particle size distribution analysis, thermal gravimetric analysis and scanning electron microscopy. The kinetic data for the zinc borate production reaction was fit by using the logistic model. The results revealed that the specific reaction rate, a model parameter, decreases with increase in particle size of zinc oxide and the presence of baffles, but increases with increase in stirring speed and purity of zinc oxide; however, it is unaffected with the changes in the amount of seed and reactants ratio. The reaction completion time is unaffected by scaling-up.

  19. Etude analytique et numérique de la réponse en vibration à hautes fréquences d'éprouvettes de fatigue vibratoire des métaux. Application aux aciers

    NASA Astrophysics Data System (ADS)

    Ben Aich, A.; El Kihel, B.; Kifani, A.; Sahban, F.

    1994-07-01

    In the present paper, the so-called " ultrasonic fatigue " or fatigue at very high frequency has been studied in the materials elastic behaviour case while neglecting the thermal effects that influence the mechanical fields. The determination of mechanical fields and specimen resonance length has been done both analytically and numerically. The numerical method used for this calculation is the finite element method (FEM). Martensitic steel " Soleil A2 " and austenitic steel " ICL 472 BC " have been considered in order to compare the two methods (analytical and numerical). It is shown that a perfect convergence is obtained between the two solutions. Dans le présent travail, la fatigue vibratoire a été étudiée dans le cas du comportement élastique des matériaux en négligeant les effets thermiques pouvant influencer les champs mécaniques. La détermination de ces champs et de la longueur de résonance des éprouvettes de fatigue a été faite analytiquement et numériquement. Le calcul numérique effectué se base sur la méthode des éléments finis. Dans le but d'une comparaison des solutions analytiques et numériques, deux aciers ont été considérés : un acier martensitique (Soleil A2) et un acier austénitique de type 18-10 (ICL 472 BC). Une parfaite convergence est obtenue entre les deux solutions.

  20. Zinc in Pancreatic Islet Biology, Insulin Sensitivity, and Diabetes

    PubMed Central

    Maret, Wolfgang

    2017-01-01

    About 20 chemical elements are nutritionally essential for humans with defined molecular functions. Several essential and nonessential biometals are either functional nutrients with antidiabetic actions or can be diabetogenic. A key question remains whether changes in the metabolism of biometals and biominerals are a consequence of diabetes or are involved in its etiology. Exploration of the roles of zinc (Zn) in this regard is most revealing because 80 years of scientific discoveries link zinc and diabetes. In pancreatic β- and α-cells, zinc has specific functions in the biochemistry of insulin and glucagon. When zinc ions are secreted during vesicular exocytosis, they have autocrine, paracrine, and endocrine roles. The membrane protein ZnT8 transports zinc ions into the insulin and glucagon granules. ZnT8 has a risk allele that predisposes the majority of humans to developing diabetes. In target tissues, increased availability of zinc enhances the insulin response by inhibiting protein tyrosine phosphatase 1B, which controls the phosphorylation state of the insulin receptor and hence downstream signalling. Inherited diseases of zinc metabolism, environmental exposures that interfere with the control of cellular zinc homeostasis, and nutritional or conditioned zinc deficiency influence the patho-biochemistry of diabetes. Accepting the view that zinc is one of the many factors in multiple gene-environment interactions that cause the functional demise of β-cells generates an immense potential for treating and perhaps preventing diabetes. Personalized nutrition, bioactive food, and pharmaceuticals targeting the control of cellular zinc in precision medicine are among the possible interventions. PMID:28401081

  1. Zinc: health effects and research priorities for the 1990s.

    PubMed Central

    Walsh, C T; Sandstead, H H; Prasad, A S; Newberne, P M; Fraker, P J

    1994-01-01

    This review critically summarizes the literature on the spectrum of health effects of zinc status, ranging from symptoms of zinc deficiency to excess exposure. Studies on zinc intake are reviewed in relation to optimum requirements as a function of age and sex. Current knowledge on the biochemical properties of zinc which are critical to the essential role of this metal in biological systems is summarized. Dietary and physiological factors influencing the bioavailability and utilization of zinc are considered with special attention to interactions with iron and copper status. The effects of zinc deficiency and toxicity are reviewed with respect to specific organs, immunological and reproductive function, and genotoxicity and carcinogenicity. Finally, key questions are identified where research is needed, such as the risks to human health of altered environmental distribution of zinc, assessment of zinc status in humans, effects of zinc status in relation to other essential metals on immune function, reproduction, neurological function, and the cardiovascular system, and mechanistic studies to further elucidate the biological effects of zinc at the molecular level. PMID:7925188

  2. Heterostructured nanohybrid of zinc oxide-montmorillonite clay.

    PubMed

    Hur, Su Gil; Kim, Tae Woo; Hwang, Seong-Ju; Hwang, Sung-Ho; Yang, Jae Hun; Choy, Jin-Ho

    2006-02-02

    We have synthesized heterostructured zinc oxide-aluminosilicate nanohybrids through a hydrothermal reaction between the colloidal suspension of exfoliated montmorillonite nanosheets and the sol solution of zinc acetate. According to X-ray diffraction, N2 adsorption-desorption isotherm, and field emission-scanning electron microscopic analyses, it was found that the intercalation of zinc oxide nanoparticles expands the basal spacing of the host montmorillonite clay, and the crystallites of the nanohybrids are assembled to form a house-of-cards structure. From UV-vis spectroscopic investigation, it becomes certain that calcined nanohybrid contains two kinds of the zinc oxide species in the interlayer space of host lattice and in mesopores formed by the house-of-cards type stacking of the crystallites. Zn K-edge X-ray absorption near-edge structure/extended X-ray absorption fine structure analyses clearly demonstrate that guest species in the nanohybrids exist as nanocrystalline zinc oxides with wurzite-type structure.

  3. Zinc Bioavailability from Phytate-Rich Foods and Zinc Supplements. Modeling the Effects of Food Components with Oxygen, Nitrogen, and Sulfur Donor Ligands.

    PubMed

    Tang, Ning; Skibsted, Leif H

    2017-10-04

    Aqueous solubility of zinc phytate (K sp = (2.6 ± 0.2) × 10 -47 mol 7 /L 7 ), essential for zinc bioavailability from plant foods, was found to decrease with increasing temperature corresponding to ΔH dis of -301 ± 22 kJ/mol and ΔS dis of -1901 ± 72 J/(mol K). Binding of zinc to phytate was found to be exothermic for the stronger binding site and endothermic for the weaker binding site. The solubility of the slightly soluble zinc citrate and insoluble zinc phytate was found to be considerably enhanced by the food components with oxygen donor, nitrogen donor, and sulfur donor ligands. The driving force for the enhanced solubility is mainly due to the complex formation between zinc and the investigated food components rather than ligand exchange and ternary complex formation as revealed by quantum mechanical calculations and isothermal titration calorimetry. Histidine and citrate are promising ligands for improving zinc absorption from phytate-rich foods.

  4. Etude épidémio-clinique des diarrhées aiguës à rotavirus chez les nourrissons à l'hôpital Jason Sendwe de Lubumbashi, République Démocratique du Congo

    PubMed Central

    Sangaji, Maguy Kabuya; Mukuku, Olivier; Mutombo, Augustin Mulangu; Mawaw, Paul Makan; Swana, Edouard Kawawa; Kabulo, Benjamin Kasongo; Mutombo, André Kabamba; Wembonyama, Stanis Okitotsho; Luboya, Oscar Numbi

    2015-01-01

    Introduction Le rotavirus est un problème de santé publique, non seulement dans les pays en développement où tous les enfants sont infectés avant l’âge de deux à trois ans mais aussi dans les pays développés où les conditions d'hygiène sont bonnes. La présente étude est la première à fournir des informations sur la prévalence de l'infection à rotavirus dans les diarrhées aiguës des nourrissons dans la ville de Lubumbashi. Elle s'est fixée comme objectifs de déterminer la fréquence hospitalière ainsi que la saisonnalité, les caractéristiques sociodémographiques, cliniques et évolutives de l'infection à Rotavirus chez les nourrissons admis à l'hôpital Jason Sendwe de Lubumbashi pour une diarrhée aiguë. Méthodes Il s'agit d'une étude descriptive et transversale menée pendant la période allant du 1er janvier au 31 décembre 2012. Les paramètres épidémio-cliniques et évolutifs (âge, sexe, saison, signes cliniques, nombre journalier de selles et évolution) des enfants diagnostiqués positifs au rotavirus ont été comparés à ceux des enfants dont le test au rotavirus était négatif. Le degré de signification était de 5%. Résultats Nous avons récolté 193 cas de diarrhées aiguës dont 104 nourrissons étaient infectés par le rotavirus soit 53,8%. Des taux élevés des diarrhées à rotavirus sont enregistrés au cours de la saison sèche comparativement à la saison des pluies (p0,05). Par ailleurs, les enfants infectés par le rotavirus étaient 6 fois plus susceptibles de présenter une déshydratation modérée/sévère (p0,05). Conclusion Le rotavirus est confirmé dans la ville de Lubumbashi et touche souvent les enfants d’âge ≤12 mois, pendant la saison sèche sans distinction de sexe et conduit rapidement à une déshydratation modérée/sévère. Une prise en charge adaptée et précoce permet d’éviter les décès et l'assainissement du milieu, le lavage des mains, la prise d'eau potable et la

  5. Zinc Levels Modulate Lifespan through Multiple Longevity Pathways in Caenorhabditis elegans

    PubMed Central

    Kumar, Jitendra; Barhydt, Tracy; Awasthi, Anjali; Lithgow, Gordon J.; Killilea, David W.; Kapahi, Pankaj

    2016-01-01

    Zinc is an essential trace metal that has integral roles in numerous biological processes, including enzymatic function, protein structure, and cell signaling pathways. Both excess and deficiency of zinc can lead to detrimental effects on development and metabolism, resulting in abnormalities and disease. We altered the zinc balance within Caenorhabditis elegans to examine how changes in zinc burden affect longevity and healthspan in an invertebrate animal model. We found that increasing zinc levels in vivo with excess dietary zinc supplementation decreased the mean and maximum lifespan, whereas reducing zinc levels in vivo with a zinc-selective chelator increased the mean and maximum lifespan in C. elegans. We determined that the lifespan shortening effects of excess zinc required expression of DAF-16, HSF-1 and SKN-1 proteins, whereas the lifespan lengthening effects of the reduced zinc may be partially dependent upon this set of proteins. Furthermore, reducing zinc levels led to greater nuclear localization of DAF-16 and enhanced dauer formation compared to controls, suggesting that the lifespan effects of zinc are mediated in part by the insulin/IGF-1 pathway. Additionally, zinc status correlated with several markers of healthspan in worms, including proteostasis, locomotion and thermotolerance, with reduced zinc levels always associated with improvements in function. Taken together, these data support a role for zinc in regulating both development and lifespan in C. elegans, and that suggest that regulation of zinc homeostasis in the worm may be an example of antagonistic pleiotropy. PMID:27078872

  6. Analysis of zinc binding sites in protein crystal structures.

    PubMed

    Alberts, I L; Nadassy, K; Wodak, S J

    1998-08-01

    The geometrical properties of zinc binding sites in a dataset of high quality protein crystal structures deposited in the Protein Data Bank have been examined to identify important differences between zinc sites that are directly involved in catalysis and those that play a structural role. Coordination angles in the zinc primary coordination sphere are compared with ideal values for each coordination geometry, and zinc coordination distances are compared with those in small zinc complexes from the Cambridge Structural Database as a guide of expected trends. We find that distances and angles in the primary coordination sphere are in general close to the expected (or ideal) values. Deviations occur primarily for oxygen coordinating atoms and are found to be mainly due to H-bonding of the oxygen coordinating ligand to protein residues, bidentate binding arrangements, and multi-zinc sites. We find that H-bonding of oxygen containing residues (or water) to zinc bound histidines is almost universal in our dataset and defines the elec-His-Zn motif. Analysis of the stereochemistry shows that carboxyl elec-His-Zn motifs are geometrically rigid, while water elec-His-Zn motifs show the most geometrical variation. As catalytic motifs have a higher proportion of carboxyl elec atoms than structural motifs, they provide a more rigid framework for zinc binding. This is understood biologically, as a small distortion in the zinc position in an enzyme can have serious consequences on the enzymatic reaction. We also analyze the sequence pattern of the zinc ligands and residues that provide elecs, and identify conserved hydrophobic residues in the endopeptidases that also appear to contribute to stabilizing the catalytic zinc site. A zinc binding template in protein crystal structures is derived from these observations.

  7. Metallic Zinc Exhibits Optimal Biocompatibility for Bioabsorbable Endovascular Stents

    PubMed Central

    Bowen, Patrick K.; Guillory, Roger J.; Shearier, Emily R.; Seitz, Jan-Marten; Drelich, Jaroslaw; Bocks, Martin; Zhao, Feng; Goldman, Jeremy

    2015-01-01

    Although corrosion resistant bare metal stents are considered generally effective, their permanent presence in a diseased artery is an increasingly recognized limitation due to the potential for long-term complications. We previously reported that metallic zinc exhibited an ideal biocorrosion rate within murine aortas, thus raising the possibility of zinc as a candidate base material for endovascular stenting applications. This study was undertaken to further assess the arterial biocompatibility of metallic zinc. Metallic zinc wires were punctured and advanced into the rat abdominal aorta lumen for up to 6.5 months. This study demonstrated that metallic zinc did not provoke responses that often contribute to restenosis. Low cell densities and neointimal tissue thickness, along with tissue regeneration within the corroding implant, point to optimal biocompatibility of corroding zinc. Furthermore, the lack of progression in neointimal tissue thickness over 6.5 months or the presence of smooth muscle cells near the zinc implant suggest that the products of zinc corrosion may suppress the activities of inflammatory and smooth muscle cells. PMID:26249616

  8. [Interaction among the trace elements zinc, copper and iron after depletion and repletion of dairy cows with zinc].

    PubMed

    Kirchgessner, M; Schwarz, F J; Roth, H P; Schwarz, W A

    1978-12-01

    Imbalances in the supply with trace elements may be caused by the excessive administration of one or several elements or the insufficient administration in relation to other trace elements. This article deals with the interactions between the trace elements zinc and copper resp. zinc and iron under the conditions of the insufficient supply with Zn (6 mg per kg dry matter of the fodder) and the supply according to the demand with other trace elements (14 mg copper resp. 83 mg iron per dry matter of the fodder). For this purpose we investigated the copper, iron and zinc content of the milk and the serum of cows that were first depleted of zinc through a semi-synthetic zinc deficiency diet and then repleted with extra allowances of zinc. The closest connections exist between the copper and zinc content of the milk. Thus extreme Zn-deficiency feeding conditions the decreased Zn-content on the one hand and increased Cu-content on the other. In contrast to this, the cows' Zn-excretion in the milk increases after Zn-repletion whereas the Cu-content decreases. This shows a distinctly negative correlation. A loose connection could only be detected for the Cu- and Zn-content of the serum. Though the Zn-content changed considerably in dependence on the Zn-supply, the Cu-content remained largely uninfluenced. The Fe-content of both milk and serum shows no interaction with the nutritive Zn-supply. Only after 19 test weeks of extreme Zn-deficiency could a slight increase of the Fe-concentration be indicated.

  9. Effect of dietary proteins on zinc bioavailability in pregnant rats.

    PubMed

    Uenishi, K; Horio, H; Manabe, S; Sakamoto, S

    1993-12-01

    In order to clarify the effects of dietary proteins on zinc bioavailability during pregnancy, two experiments were carried out. In Experiment 1, changes in zinc retention due to pregnancy (difference in retention between pregnant and nonpregnant animals) during early-mid and late pregnancy were examined in rats fed 10 and 20% egg white diets. Total amounts of retained zinc due to pregnancy were about 1000 micrograms or slightly more, equal to the zinc content in the products of conception at term. However, extra zinc retention during late pregnancy ranged between only 20 to 40% of overall retention, suggesting that almost all zinc retained during early-mid pregnancy moved from the mothers to the fetuses near term. Zinc retention in early-mid and late periods of pregnancy was higher in pregnant than nonpregnant rats, due mainly to increases in intake and bioavailability. In Experiment 2, to examine the effects of quality and quantity of dietary proteins, pregnant rats were fed either 10 or 20% egg white (EW), whole egg (WE), casein (C) and soy protein isolate with or without methionine (SM and S, respectively) diets. Total zinc retention during pregnancy was affected by both zinc and nitrogen intakes, though the former effect was greater than the latter. Because rats fed the EW diets retained dietary zinc efficiently, a relationship between zinc retention (Y, microgram/100 g BW/21 d.) and zinc intake (X, microgram/100 g BW/21 d.) was also examined in the non-EW protein groups, resulting in the following regression equation: Y = 0.471X-1790 (n: 51, r = 0.81, p < 0.001). Dietary protein quality affected the food intake resulting in different zinc intake and retention during pregnancy. Zinc from EW diets was more available than from the other four protein diets, because similar plots for rats fed the 10 and 20% EW diets fell above this line. Reasons for efficient bioavailability of zinc in EW were discussed in connection with the forms of zinc in diets and the

  10. Etude des proprietes de surface et des proprietes rheologiques des melanges polymeres thermotropes

    NASA Astrophysics Data System (ADS)

    Tovar Hernandez, Maria Gabriela

    We studied the surface and rheological properties of thermotropic liquid crystal polymers (TLCP) mixed with thermoplastics. We first investigated acid-base interactions in polymer component as a function of temperature, and could identified the many phase changes in TLCP. We found that acid-base interactions in TLCP decrease significantly with temperature, down to a point Tc where they become negligible. To our knowledge, it is the first time such observation is reported concerning TLCP. Acid-base interactions in the thermoplastics also vary with temperature, but they remain non-negligible, and reach a plateau at high temperature. In theory, one can obtain compatible blends between polymers A and B when their interaction parameters are both small and similar. The negligible acid-base parameter of TLCP at T > Tc should enhance the compatibility with thermoplastics. For that reason, we prepared the TLCP/thermoplastic blends at temperatures superior and inferior to Tc. We restricted our investigation to blends prepared in a Brabender Plasticorder in order to control the temperature in the mixing chamber and reduce the effects of TLCP domains deformation and reorientation. We prepared Vectra/polycarbonate blends, optimizing the drying conditions and the TLCP concentration. We optimized the drying conditions based on our previous results, finding that the transesterification reaction in presence of water happens at high temperature. Transesterification reaction was identified using infrared spectroscopy in the polymer components and in the blends. We found that this reaction occurring mainly between the ester groups in the polymer components. The product of this reaction, concentrated at the interfaces, has a remarkable effect on the blend morphology, similar to the one in compatible blend, and on its mechanical properties. To measure the effect of transesterification at the interfaces, we studied the linear viscoelasticity properties of Vectra/polycarbonate blend and their relation with their morphology. We found from the time variation of the elastic modulus at very low frequencies that the transesterification reaction was still occurring during rheological measurements. We observed coalescence of the dispersed phase droplets in all blends. Size of the droplets changed with the blend composition, the preparation temperature and the rheological characterization temperature. In addition, we compared Palierne (1990, 1991) and Lee-Park models when applied to Vectra/polycarbonate blends. We found that the Palierne model does not predict the rheological behavior of the blend, due to the mixture rule used in that model. Lee-Park model, using a different mixture rule, gives a good prediction of the linear viscoelastic properties. We succeeded in modeling the Vectra/polycarbonate rheological properties combining the characteristic relaxation times of the Palierne and Lee-Park models. Using this approach, we could clearly show that the decrease of the interfacial tension is due to the copolymer produced at the interface by transesterification reaction.

  11. The Zinc-Responsive Regulator Zur Controls a Zinc Uptake System and Some Ribosomal Proteins in Streptomyces coelicolor A3(2)▿

    PubMed Central

    Shin, Jung-Ho; Oh, So-Young; Kim, Soon-Jong; Roe, Jung-Hye

    2007-01-01

    In various bacteria, Zur, a zinc-specific regulator of the Fur family, regulates genes for zinc transport systems to maintain zinc homeostasis. It has also been suggested that Zur controls zinc mobilization by regulating some ribosomal proteins. The antibiotic-producing soil bacterium Streptomyces coelicolor contains four genes for Fur family regulators, and one (named zur) is located downstream of the znuACB operon encoding a putative zinc uptake transporter. We found that zinc specifically repressed the level of znuA transcripts and that this level was derepressed in a Δzur mutant. Purified Zur existing as homodimers bound to the znuA promoter region in the presence of zinc, confirming the role of Zur as a zinc-responsive repressor. We analyzed transcripts for paralogous forms of ribosomal proteins L31 (RpmE1 and RpmE2) and L33 (RpmG2 and RpmG3) for their dependence on Zur and found that RpmE2 and RpmG2 with no zinc-binding motif of conserved cysteines (C's) were negatively regulated by Zur. C-negative RpmG3 and C-positive RpmE1 were not regulated by Zur. Instead, they were regulated by the sigma factor σR as predicted from their promoter sequences. The rpmE1 and rpmG3 genes were partially induced by EDTA in a manner dependent on σR, suggesting that zinc depletion may stimulate the σR regulatory system. This finding reflects a link between thiol-oxidizing stress and zinc depletion. We determined the Zur-binding sites within znuA and rpmG2 promoter regions by footprinting analyses and identified a consensus inverted repeat sequence (TGaaAatgatTttCA, where uppercase letters represent the nucleotides common to all sites analyzed). This sequence closely matches that for mycobacterial Zur and allows the prediction of more genes in the Zur regulon. PMID:17416659

  12. Effets perturbateurs endocriniens des pesticides organochlores.

    PubMed

    Charlier, C; Plomteux, G

    2002-01-01

    Xenoestrogens such organochlorine pesticides are known to induce changes in reproductive development, function or behaviour in wildlife. Because these compounds are able to modify the estrogens metabolism, or to compete with estradiol for binding to the estrogen receptor, it may be possible that these products affect the risk of developing impaired fertility, precocious puberty or some kinds of cancer in man. Le plus ancien récit de lutte contre la pollution remonte à une légende indienne racontant que la divinité Sing-bonga était incommodée par les émanations des fours dans lesquels les Asuras fondaient leurs métaux (1). Evidemment depuis, la problématique n-a cessé de s-accroître et la contamination de la Terre par de nombreux polluants est devenue aujourd-hui un problème majeur de notre Société. La protection de notre environnement est une question capitale qui doit être respectée malgré la pression économique actuelle et qui ne cessera de croître au cours des prochaines années même si l-identification objective et indiscutable de ce qui est essentiel - donc devant être prioritairement garanti sur la planète - est difficile à cerner (2). « Un oiseau en mauvais état ne pond pas de bons oeufs » disait un proverbe grec. Mais ce n-est qu-à partir de la seconde moitié du XXème siècle que les toxicologues ont commencé à identifier les effets qu-avaient entraînés à l-échelle mondiale les pollutions émises aux XIXème siècle sur la faune sauvage et sur le cheptel (3). L-histoire contemporaine des pesticides industriels commence vers 1874 (synthèse des organochlorés) et se poursuit tout au long de ces 2 siècles en passant par la synthèse des organophosphorés (1950), des carbamates (1970) et des pyréthroïdes (1975) (4). Le dichlorodiphényltrichloroéthane (DDT) a été synthétisé pour la première fois par un étudiant en cours de préparation de sa thèse de doctorat : Othmer Zeidler. La production, reprise par les

  13. Efficacy of zinc sulfate supplement on febrile seizure recurrence prevention in children with normal serum zinc level: A randomised clinical trial.

    PubMed

    Fallah, Razieh; Sabbaghzadegan, Saeideh; Karbasi, Sedighah Akhavan; Binesh, Fariba

    2015-01-01

    Serum zinc level might be related to pathogenesis of febrile seizure (FS). The purpose of this study was to evaluate efficacy and safety of oral zinc supplementation on FS recurrence prevention in non-zinc-deficient children. In a randomized clinical study, one hundred 18 to 60 mo old children with normal zinc level with first simple FS were referred to Shahid Sadoughi Hospital, Yazd, Iran from May 2012 to June 2013, were randomly assigned to two groups to receive 2 mg/kg/d zinc sulfate for six consecutive months or placebo as control group and were followed up for 1 y for FS recurrence. 41 girls and 59 boys with mean age of 2.47 ± 1.01 y were evaluated. Race, mean weight, height and body fat were similar in both groups. FS recurrence occurred in 19 children (38%) in the control group [95% confidence interval (CI): 19.45%-53.95%] and in 11 children (22%) in the zinc sulfate (95% CI: 57.47%-89.13%) groups, respectively; and the zinc group had lower FS recurrence (P = 0.03). The mean serum zinc level before intervention was lower in children with FS recurrence (72.43 ± 14.58 μg/dL versus 96.33 ± 12.69 μg/dL, P = 0.04). Gastrointestinal side effects (vomiting in five children, heartburn in two children and abdominal pain in one child) were seen in 16% of the zinc group and vomiting occurred in two children (4%) in control group and frequency of adverse events was similar in the two groups (P = 0.1). Zinc supplementation should be considered as effective and safe in prevention of FS recurrence. Copyright © 2015 Elsevier Inc. All rights reserved.

  14. Effets thermoelectrique et thermomagnetique du yttrium barium copper oxide monocristallin

    NASA Astrophysics Data System (ADS)

    Ghamlouche, Hassan

    1998-09-01

    Des la decouverte des supraconducteurs a haute temperature critique, les recherches se sont intensifiees afin de comprendre les mecanismes qui sont a l'origine des proprietes de ces materiaux L'etat mixte, tout comme l'etat supraconducteur pur et l'etat normal, a fait l'objet de nombreux travaux de recherche. En particulier, la structure des vortex a l'etat mixte, et leur mouvement sous l'effet d'une force quelconque, etaient et restent le centre de preoccupation. Les effets thermoelectrique (Seebeck) et thermomagnetique (Nernst) sont parmi les differentes mesures qui peuvent donner de l'information sur les etats des vortex a l'etat mixte. L'avantage essentiel de ces deux effets est l'absence d'un courant electrique applique. Ce dernier peut donner des perturbations indesirables durant les mesures. D'autre pari, nous avons utilise la methode CA (Courant Alternatif) pour effectuer nos mesures. Cette methode est caracterisee par une meilleure resolution par rapport a la methode CC (Courant Continu) conventionnelle. Nous avons etudie autant des echantillons macles que des echantillons sans macles. D'abord nous avons teste notre montage a champ magnetique nul. Nous avons alors montre que le pic rapporte par certains dans l'effet Seebeck a la transition supraconductrice ne correspond pas a une realite physique mais a un artefact experimental. On avait associe ce pic aux fluctuations. Par la suite, nous avons mis en evidence et etudie pour la premiere fois avec les effets Seebeck et Nernst le phenomene de la fusion du reseau de vortex grace a des mesures sur les echantillons sans macles. Cette etude s'est faite pour deux concentrations d'oxygene differentes et pour un gradient de temperature parallele, consecutivement, aux deux axes cristallographiques dans le plan ab. Finalement, nous avons etudie l'effet des plans de maclage sur le mouvement des vortex. Ceci a ete realise en appliquant le gradient de temperature selon trois directions differentes (0, 45 et 90°) avec

  15. Neurotoxicity of dental amalgam is mediated by zinc.

    PubMed

    Lobner, D; Asrari, M

    2003-03-01

    The use of dental amalgam is controversial largely because it contains mercury. We tested whether amalgam caused toxicity in neuronal cultures and whether that toxicity was caused by mercury. In this study, we used cortical cell cultures to show for the first time that amalgam causes nerve cell toxicity in culture. However, the toxicity was not blocked by the mercury chelator, 2,3-dimercaptopropane-1-sulphonate (DMPS), but was blocked by the metal chelator, calcium disodium ethylenediaminetetraacetate (CaEDTA). DMPS was an effective mercury chelator in this system, since it blocked mercury toxicity. Of the components that comprise amalgam (mercury, zinc, tin, copper, and silver), only zinc neurotoxicity was blocked by CaEDTA. These results indicate that amalgam is toxic to nerve cells in culture by releasing zinc. While zinc is known to be neurotoxic, ingestion of zinc is not a major concern because zinc levels in the body are tightly regulated.

  16. Preface: Materiaux 2010

    NASA Astrophysics Data System (ADS)

    Cheikhrouhou, Abdelwaheb

    2012-02-01

    Ceramics, glasses, polymers Natural materials (phosphates, clay,...) Metallic materials, alloys, metallurgy,... Others (materials and environment, materials and energy, biomaterials,...) I want to thank the scientific committee, the organizing committee, the local committee and everyone who contributed to the organization of this meeting for their invaluable efforts in order to guarantee the complete success of this conference. Abdelwaheb Cheikhrouhou President of 'Tu-MRS' Chairman of the Conference 'MATERIAUX 2010' Conference photograph Committies Organizing Committee Chairman CHEIKHROUHOU Abdelwaheb (Faculté des Sciences de Sfax) Members ALAYA Sahbi (Faculté des Sciences de Gabès) BENNACEUR Raouf (Faculté des Sciences de Tunis) BEN SALEM Mohamed (Faculté des Sciences de Bizerte) CHEIKHROUHOU-KOUBAA Wissem (Faculté des Sciences de Sfax) EL JANI Belgacem (Faculté des Sciences de Monastir) EZZAOUIA Hatem (Centre de Recherches et de Technologies de l'Energie, Technopole de Borj Cédria) LAMLOUMI Jilani (Ecole Supérieure des Sciences et Techniques de Tunis) REZIG Bahri (Ecole Nationale d'Ingénieurs de Tunis) Local Committee Chairman CHEIKHROUHOU Abdelwaheb (Faculté des Sciences de Sfax) Members CHEIKHROUHOU-KOUBAA Wissem (Faculté des Sciences de Sfax) KOUBAA Mohamed (Institut Supérieur de Biotechnologie de Sfax) NJEH Anwar (Institut Préparatoire aux Etudes d'Ingénieurs de Sfax) BEN SALAH Issam (Faculté des Sciences de Sfax) TAKKALI Férid (Faculté des Sciences de Sfax) REGAIEG Yassin (Faculté des Sciences de Sfax) OTHMANI Safa (Faculté des Sciences de Sfax) MNASSRI Rafik (Faculté des Sciences de Sfax) Secretariat BEN GHOZLEN Afifa (Faculté des Sciences de Sfax) BOUGHARIOU Sana (Faculté des Sciences de Sfax) Scientific Committee M. ADDOU, Faculté des Sciences de Kénitra (Morocco) N. AMDOUNI, Faculté des Sciences de Tunis (Tunisia) M. BACCOUCHE, Faculté des Sciences d'Annaba (Algeria) H. BATIS, Faculté des Sciences de Tunis (Tunisia) A. BELAFHAL

  17. Two zinc-binding domains in the transporter AdcA from Streptococcus pyogenes facilitate high-affinity binding and fast transport of zinc.

    PubMed

    Cao, Kun; Li, Nan; Wang, Hongcui; Cao, Xin; He, Jiaojiao; Zhang, Bing; He, Qing-Yu; Zhang, Gong; Sun, Xuesong

    2018-04-20

    Zinc is an essential metal in bacteria. One important bacterial zinc transporter is AdcA, and most bacteria possess AdcA homologs that are single-domain small proteins due to better efficiency of protein biogenesis. However, a double-domain AdcA with two zinc-binding sites is significantly overrepresented in Streptococcus species, many of which are major human pathogens. Using molecular simulation and experimental validations of AdcA from Streptococcus pyogenes , we found here that the two AdcA domains sequentially stabilize the structure upon zinc binding, indicating an organization required for both increased zinc affinity and transfer speed. This structural organization appears to endow Streptococcus species with distinct advantages in zinc-depleted environments, which would not be achieved by each single AdcA domain alone. This enhanced zinc transport mechanism sheds light on the significance of the evolution of the AdcA domain fusion, provides new insights into double-domain transporter proteins with two binding sites for the same ion, and indicates a potential target of antimicrobial drugs against pathogenic Streptococcus species. © 2018 by The American Society for Biochemistry and Molecular Biology, Inc.

  18. Zinc alloy enhances strength and creep resistance

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Machler, M.

    1996-10-01

    A family of high-performance ternary zinc-copper-aluminum alloys has been developed that provides higher strength, hardness, and creep resistance than the traditional zinc-aluminum alloys Zamak 3, Zamak 5, and ZA-8. Designated ACuZinc, mechanical properties comparable to those of more expensive materials make it suitable for high-load applications and those at elevated temperatures. This article describes the alloy`s composition, properties, and historical development.

  19. Zinc-catalyzed allenylations of aldehydes and ketones.

    PubMed

    Fandrick, Daniel R; Saha, Jaideep; Fandrick, Keith R; Sanyal, Sanjit; Ogikubo, Junichi; Lee, Heewon; Roschangar, Frank; Song, Jinhua J; Senanayake, Chris H

    2011-10-21

    The general zinc-catalyzed allenylation of aldehydes and ketones with an allenyl boronate is presented. Preliminary mechanistic studies support a kinetically controlled process wherein, after a site-selective B/Zn exchange to generate a propargyl zinc intermediate, the addition to the electrophile effectively competes with propargyl-allenyl zinc equilibration. The utility of the methodology was demonstrated by application to a rhodium-catalyzed [4+2] cycloaddition. © 2011 American Chemical Society

  20. Properties of ice-cream fortified with zinc and Lactobacillus casei.

    PubMed

    Gheisari, Hamid R; Ahadi, Leila; Khezli, Sanaz; Dehnavi, Tayebeh

    2016-01-01

    In this study, the possible effects of zinc on physicochemical properties of ice cream and the survival of Lactobacillus casei during a 90 days storage at -18°C was investigated. Samples were divided into four experimental groups as follows: control, zinc fortified ice cream, probiotic ice cream, zinc fortified and probiotic ice cream. The physicochemical, texture, organoleptic properties and the survival of probiotics, were investigated. Results showed that the addition of zinc did not affect the textural properties of ice creams. Viscosity and pH were independently decreased in all groups in the presence of zinc. A significant increase in the lipid oxidation rate especially in the zinc fortified group was also observed. The probiotic counts were maintained above the least advised quantities (106 cfu/g) which were subsequently reduced following the three months of storage. In the zinc fortified samples, the counts were higher compared to the other groups with no zinc addition. The addition of probiotics and zinc had no significant effect on the sensory properties of ice cream. As a final conclusion, the commercial production of zinc fortified ice cream is recommended.

  1. Identification des parametres du moteur de l'avion Cessna Citation X pour la phase de croisiere a partir des tests en vol et a base des reseaux de neurones =

    NASA Astrophysics Data System (ADS)

    Zaag, Mahdi

    La disponibilite des modeles precis des avions est parmi les elements cles permettant d'assurer leurs ameliorations. Ces modeles servent a ameliorer les commandes de vol et de concevoir de nouveaux systemes aerodynamiques pour la conception des ailes deformables des avions. Ce projet consiste a concevoir un systeme d'identification de certains parametres du modele du moteur de l'avion d'affaires americain Cessna Citation X pour la phase de croisiere a partir des essais en vol. Ces essais ont ete effectues sur le simulateur de vol concu et fabrique par CAE Inc. qui possede le niveau D de la dynamique de vol. En effet, le niveau D est le plus haut niveau de precision donne par l'autorite federale de reglementation FAA de l'aviation civile aux Etats-Unis. Une methodologie basee sur les reseaux de neurones optimises a l'aide d'un algorithme intitule le "grand deluge etendu" est utilisee dans la conception de ce systeme d'identification. Plusieurs tests de vol pour differentes altitudes et differents nombres de Mach ont ete realises afin de s'en servir comme bases de donnees pour l'apprentissage des reseaux de neurones. La validation de ce modele a ete realisee a l'aide des donnees du simulateur. Malgre la nonlinearite et la complexite du systeme, les parametres du moteur ont ete tres bien predits pour une enveloppe de vol determinee. Ce modele estime pourrait etre utilise pour des analyses de fonctionnement du moteur et pourrait assurer le controle de l'avion pendant cette phase de croisiere. L'identification des parametres du moteur pourrait etre realisee aussi pour les autres phases de montee et de descente afin d'obtenir son modele complet pour toute l'enveloppe du vol de l'avion Cessna Citation X (montee, croisiere, descente). Cette methode employee dans ce travail pourrait aussi etre efficace pour realiser un modele pour l'identification des coefficients aerodynamiques du meme avion a partir toujours des essais en vol. None None None

  2. Long Life, High Energy Silver-Zinc Batteries

    NASA Technical Reports Server (NTRS)

    Kainthla, Ramesh; Coffey, Brendan

    2003-01-01

    This viewgraph presentation includes: 1) an introduction to RBC Technologies; 2) Rechargeable Zinc Alkaline (RZA(tm)) Systems which include MnO2/Zn, Ni/Zn, Ag/Zn, and Zn/Air; and 3) RZA Silver/Zinc Battery Developments. Conclusions include the following: 1)Issues with long term wet life and cycle life of the silver/zinc battery system are being overcome through the use of new anode formulations and separator designs; 2) Performance may exceed 200 cycles to 80% of initial capacity and ultimate wet-life of > 36 months; and 3) Rechargeable silver/zinc batteries available in prismatic and cylindrical formats may provide a high energy, high power alternative to lithium-ion in military/aerospace applications.

  3. Elaboration de nouvelles approches micromecaniques pour l'optimisation des performances mecaniques des materiaux heterogenes

    NASA Astrophysics Data System (ADS)

    Aboutajeddine, Ahmed

    Les modeles micromecaniques de transition d'echelles qui permettent de determiner les proprietes effectives des materiaux heterogenes a partir de la microstructure sont consideres dans ce travail. L'objectif est la prise en compte de la presence d'une interphase entre la matrice et le renforcement dans les modeles micromecaniques classiques, de meme que la reconsideration des approximations de base de ces modeles, afin de traiter les materiaux multiphasiques. Un nouveau modele micromecanique est alors propose pour tenir compte de la presence d'une interphase elastique mince lors de la determination des proprietes effectives. Ce modele a ete construit grace a l'apport de l'equation integrale, des operateurs interfaciaux de Hill et de la methode de Mori-Tanaka. Les expressions obtenues pour les modules globaux et les champs dans l'enrobage sont de nature analytique. L'approximation de base de ce modele est amelioree par la suite dans un nouveau modele qui s'interesse aux inclusions enrobees avec un enrobage mince ou epais. La resolution utilisee s'appuie sur une double homogeneisation realisee au niveau de l'inclusion enrobee et du materiau. Cette nouvelle demarche, permettra d'apprehender completement les implications des approximations de la modelisation. Les resultats obtenus sont exploites par la suite dans la solution de l'assemblage de Hashin. Ainsi, plusieurs modeles micromecaniques classiques d'origines differentes se voient unifier et rattacher, dans ce travail, a la representation geometrique de Hashin. En plus de pouvoir apprecier completement la pertinence de l'approximation de chaque modele dans cette vision unique, l'extension correcte de ces modeles aux materiaux multiphasiques est rendue possible. Plusieurs modeles analytiques et explicites sont alors proposee suivant des solutions de differents ordres de l'assemblage de Hashin. L'un des modeles explicite apparait comme une correction directe du modele de Mori-Tanaka, dans les cas ou celui ci echoue a

  4. Relation entre les caractéristiques des table-bancs et les mesures anthropométriques des écoliers au Benin

    PubMed Central

    Falola, Stève Marjelin; Gouthon, Polycarpe; Falola, Jean-Marie; Fiogbe, Michel Armand; Nigan, Issiako Bio

    2014-01-01

    Introduction Le mobilier scolaire et la posture assise en classe sont souvent impliqués dans l'apparition des douleurs rachidiennes, influant de fait sur la qualité des tâches réalisées par les apprenants. Aucune étude n'a encore vérifié le degré d'adéquation entre les caractéristiques du mobilier et celles des écoliers au Bénin. L'objectif de cette étude transversale est donc de déterminer la relation entre les dimensions des table-bancs utilisées en classe et les mesures anthropométriques des écoliers au Bénin. Methods Elle a été réalisée avec un échantillon probabiliste de 678 écoliers, âgés de 4 à 17 ans. Les mesures anthropométriques des écoliers et les mensurations relatives aux longueurs, largeurs et hauteurs des table-bancs ont été mesurées, puis intégrées aux équations proposées dans la littérature. Les pourcentages des valeurs situées hors des limitesacceptables, dérivées de l'application des équations ont été calculés. Results La largeur et la hauteur des table-bancs utilisées par les écoliers étaient plus élevées (p < 0,05) que les valeurs de référence recommandées par les structures officielles de contrôle et de production des mobiliers scolaires au Bénin. Quel que soit le sexe, il y avait une inadéquation entre la largeur du banc et la longueur fesse-poplité, puis entre la hauteur de la table et la distance coude-bancdes écoliers. Conclusion Les résultats suggèrent de prendre en compte l’évolution des mesures anthropométriques des écoliers dans la confection des table-bancs, afin de promouvoir de bonnes postures assises en classe et de réduire le risque de troubles du rachis. PMID:25317232

  5. Profil épidémiologique des tumeurs malignes primitives des glandes salivaires : à propos de 154 cas

    PubMed Central

    Setti, Khadija; Mouanis, Mohamed; Moumni, Abdelmounim; Maher, Mostafa; Harmouch, Amal

    2014-01-01

    Introduction Les tumeurs des glandes salivaires sont des tumeurs rares représentant 3à 5% des tumeurs de la tête et du cou. La classification de l'OMS 2005 distingue les tumeurs épithéliales, les tumeurs mésenchymateuses, les tumeurs hématologiques et les tumeurs secondaires. Méthodes Notre travail consiste en une étude rétrospective réalisée sur une période de 10 ans allant de janvier 2002 à janvier 2012. Les critères d'inclusion étaient: l'âge, le sexe, le siège de la tumeur et le type histologique. Résultats L'incidence annuelle des tumeurs malignes primitives des glandes salivaires dans notre série était de 15 cas par an. Cent cinquante quatre cas de tumeurs malignes primitives des glandes salivaires ont été colligés sans prédominance de sexe (78 femmes (50,6%) et 76 hommes (49,4%)). La moyenne d'âge était de 60 ans avec des extrêmes de 4 et 83 ans et un pic de fréquence entre 51et 70 ans. Deux tiers des cas (65%) avaient une localisation au niveau des glandes principales avec 66 cas au niveau de la parotide (43%) et 34 cas au niveau de la glande sous maxillaire (22%). Cinquante quatre patients avaient une tumeur maligne des glandes salivaires accessoires (35%) dont 61% au niveau du palais. Aucun cas de tumeur maligne de la glande sublinguale n'a été recensé dans notre étude. Le type histologique prédominant dans notre série était le carcinome adénoïde kystique et retrouvé chez 43 patients (27,9%), suivi de l'adénocarcinome sans autre indication chez 37 patients (24%) puis du carcinome mucoépidermoïde chez 16 patients (10,4%) et de l'adénocarcinome polymorphe de bas grade également chez 16 patients (10. 4%). Conclusion Les tumeurs malignes des glandes salivaires représentent un ensemble hétérogène de maladies de caractérisation complexe et de fréquence variable. PMID:25120861

  6. Using XML to encode TMA DES metadata.

    PubMed

    Lyttleton, Oliver; Wright, Alexander; Treanor, Darren; Lewis, Paul

    2011-01-01

    The Tissue Microarray Data Exchange Specification (TMA DES) is an XML specification for encoding TMA experiment data. While TMA DES data is encoded in XML, the files that describe its syntax, structure, and semantics are not. The DTD format is used to describe the syntax and structure of TMA DES, and the ISO 11179 format is used to define the semantics of TMA DES. However, XML Schema can be used in place of DTDs, and another XML encoded format, RDF, can be used in place of ISO 11179. Encoding all TMA DES data and metadata in XML would simplify the development and usage of programs which validate and parse TMA DES data. XML Schema has advantages over DTDs such as support for data types, and a more powerful means of specifying constraints on data values. An advantage of RDF encoded in XML over ISO 11179 is that XML defines rules for encoding data, whereas ISO 11179 does not. We created an XML Schema version of the TMA DES DTD. We wrote a program that converted ISO 11179 definitions to RDF encoded in XML, and used it to convert the TMA DES ISO 11179 definitions to RDF. We validated a sample TMA DES XML file that was supplied with the publication that originally specified TMA DES using our XML Schema. We successfully validated the RDF produced by our ISO 11179 converter with the W3C RDF validation service. All TMA DES data could be encoded using XML, which simplifies its processing. XML Schema allows datatypes and valid value ranges to be specified for CDEs, which enables a wider range of error checking to be performed using XML Schemas than could be performed using DTDs.

  7. Using XML to encode TMA DES metadata

    PubMed Central

    Lyttleton, Oliver; Wright, Alexander; Treanor, Darren; Lewis, Paul

    2011-01-01

    Background: The Tissue Microarray Data Exchange Specification (TMA DES) is an XML specification for encoding TMA experiment data. While TMA DES data is encoded in XML, the files that describe its syntax, structure, and semantics are not. The DTD format is used to describe the syntax and structure of TMA DES, and the ISO 11179 format is used to define the semantics of TMA DES. However, XML Schema can be used in place of DTDs, and another XML encoded format, RDF, can be used in place of ISO 11179. Encoding all TMA DES data and metadata in XML would simplify the development and usage of programs which validate and parse TMA DES data. XML Schema has advantages over DTDs such as support for data types, and a more powerful means of specifying constraints on data values. An advantage of RDF encoded in XML over ISO 11179 is that XML defines rules for encoding data, whereas ISO 11179 does not. Materials and Methods: We created an XML Schema version of the TMA DES DTD. We wrote a program that converted ISO 11179 definitions to RDF encoded in XML, and used it to convert the TMA DES ISO 11179 definitions to RDF. Results: We validated a sample TMA DES XML file that was supplied with the publication that originally specified TMA DES using our XML Schema. We successfully validated the RDF produced by our ISO 11179 converter with the W3C RDF validation service. Conclusions: All TMA DES data could be encoded using XML, which simplifies its processing. XML Schema allows datatypes and valid value ranges to be specified for CDEs, which enables a wider range of error checking to be performed using XML Schemas than could be performed using DTDs. PMID:21969921

  8. Biphasic zinc compartmentalisation in a human fungal pathogen.

    PubMed

    Crawford, Aaron C; Lehtovirta-Morley, Laura E; Alamir, Omran; Niemiec, Maria J; Alawfi, Bader; Alsarraf, Mohammad; Skrahina, Volha; Costa, Anna C B P; Anderson, Andrew; Yellagunda, Sujan; Ballou, Elizabeth R; Hube, Bernhard; Urban, Constantin F; Wilson, Duncan

    2018-05-01

    Nutritional immunity describes the host-driven manipulation of essential micronutrients, including iron, zinc and manganese. To withstand nutritional immunity and proliferate within their hosts, pathogenic microbes must express efficient micronutrient uptake and homeostatic systems. Here we have elucidated the pathway of cellular zinc assimilation in the major human fungal pathogen Candida albicans. Bioinformatics analysis identified nine putative zinc transporters: four cytoplasmic-import Zip proteins (Zrt1, Zrt2, Zrt3 and orf19.5428) and five cytoplasmic-export ZnT proteins (orf19.1536/Zrc1, orf19.3874, orf19.3769, orf19.3132 and orf19.52). Only Zrt1 and Zrt2 are predicted to localise to the plasma membrane and here we demonstrate that Zrt2 is essential for C. albicans zinc uptake and growth at acidic pH. In contrast, ZRT1 expression was found to be highly pH-dependent and could support growth of the ZRT2-null strain at pH 7 and above. This regulatory paradigm is analogous to the distantly related pathogenic mould, Aspergillus fumigatus, suggesting that pH-adaptation of zinc transport may be conserved in fungi and we propose that environmental pH has shaped the evolution of zinc import systems in fungi. Deletion of C. albicans ZRT2 reduced kidney fungal burden in wild type, but not in mice lacking the zinc-chelating antimicrobial protein calprotectin. Inhibition of zrt2Δ growth by neutrophil extracellular traps was calprotectin-dependent. This suggests that, within the kidney, C. albicans growth is determined by pathogen-Zrt2 and host-calprotectin. As well as serving as an essential micronutrient, zinc can also be highly toxic and we show that C. albicans deals with this potential threat by rapidly compartmentalising zinc within vesicular stores called zincosomes. In order to understand mechanistically how this process occurs, we created deletion mutants of all five ZnT-type transporters in C. albicans. Here we show that, unlike in Saccharomyces cerevisiae, C

  9. Les soins aux enfants et aux adolescents des familles des militaires canadiens : les considérations particulières

    PubMed Central

    Rowan-Legg, Anne

    2017-01-01

    Résumé Les familles des militaires font face à de nombreux facteurs de stress, tels que les réinstallations fréquentes, les longues pério des de séparation familiale, l’isolement géographique du réseau de soutien de la famille élargie et le déploiement en zones très dangereuses. Les enfants et les adolescents des familles des militaires vivent les mêmes trajectoires développementales et motivationnelles que leurs homologues civils, mais ils sont également aux prises avec des pressions et des facteurs de stress liés à leur développement qui sont inhabituels et qui leur sont imposés par les exigences de la vie militaire. Les effets de la vie militaire sur les familles et les enfants commencent à être admis et mieux caractérisés. Il est essentiel de comprendre les préoccupations propres aux enfants et aux adolescents des familles des militaires et de mobiliser les ressources nécessaires pour les soutenir afin de répondre à leurs besoins en matière de santé.

  10. Zinc Modulates Nanosilver-Induced Toxicity in Primary Neuronal Cultures.

    PubMed

    Ziemińska, Elżbieta; Strużyńska, Lidia

    2016-02-01

    Silver nanoparticles (NAg) have recently become one of the most commonly used nanomaterials. Since the ability of nanosilver to enter the brain has been confirmed, there has been a need to investigate mechanisms of its neurotoxicity. We previously showed that primary neuronal cultures treated with nanosilver undergo destabilization of calcium homeostasis via a mechanism involving glutamatergic NMDA receptors. Considering the fact that zinc interacts with these receptors, the aim of the present study was to examine the role of zinc in mechanisms of neuronal cell death in primary cultures. In cells treated with nanosilver, we noted an imbalance between extracellular and intracellular zinc levels. Thus, the influence of zinc deficiency and supplementation on nanosilver-evoked cytotoxicity was investigated by treatment with TPEN (a chelator of zinc ions), or ZnCl(2), respectively. Elimination of zinc leads to complete death of nanosilver-treated CGCs. In contrast, supplementation with ZnCl(2) increases viability of CGCs in a dose-dependent manner. Addition of zinc provided protection against the extra/intracellular calcium imbalance in a manner similar to MK-801, an antagonist of NMDA receptors. Zinc chelation by TPEN decreases the mitochondrial potential and dramatically increases the rate of production of reactive oxygen species. Our results indicate that zinc supplementation positively influences nanosilver-evoked changes in CGCs. This is presumed to be due to an inhibitory effect on NMDA-sensitive calcium channels.

  11. Effects of Zinc on Particulate Methane Monooxygenase Activity and Structure*

    PubMed Central

    Sirajuddin, Sarah; Barupala, Dulmini; Helling, Stefan; Marcus, Katrin; Stemmler, Timothy L.; Rosenzweig, Amy C.

    2014-01-01

    Particulate methane monooxygenase (pMMO) is a membrane-bound metalloenzyme that oxidizes methane to methanol in methanotrophic bacteria. Zinc is a known inhibitor of pMMO, but the details of zinc binding and the mechanism of inhibition are not understood. Metal binding and activity assays on membrane-bound pMMO from Methylococcus capsulatus (Bath) reveal that zinc inhibits pMMO at two sites that are distinct from the copper active site. The 2.6 Å resolution crystal structure of Methylocystis species strain Rockwell pMMO reveals two previously undetected bound lipids, and metal soaking experiments identify likely locations for the two zinc inhibition sites. The first is the crystallographic zinc site in the pmoC subunit, and zinc binding here leads to the ordering of 10 previously unobserved residues. A second zinc site is present on the cytoplasmic side of the pmoC subunit. Parallels between these results and zinc inhibition studies of several respiratory complexes suggest that zinc might inhibit proton transfer in pMMO. PMID:24942740

  12. Lignes directrices canadiennes sur l’utilisation sécuritaire et efficace des opioïdes pour la douleur chronique non cancéreuse

    PubMed Central

    Kahan, Meldon; Wilson, Lynn; Mailis-Gagnon, Angela; Srivastava, Anita

    2011-01-01

    Résumé Objectif Présenter aux médecins de famille un résumé clinique pratique sur la prescription d’opioïdes à des populations particulières en se fondant sur les recommandations faites dans les lignes directrices canadiennes sur l’utilisation sécuritaire et efficace des opioïdes pour la douleur chronique non cancéreuse. Qualité des données Pour produire les lignes directrices, les chercheurs ont effectué une synthèse critique de la littérature médicale en insistant plus précisément sur les études de l’efficacité et de la sécurité des opioïdes dans des populations particulières. Message principal Les médecins de famille peuvent atténuer les risques de surdose, de sédation, d’usage abusif et de dépendance grâce à des stratégies adaptées à l’âge et à l’état de santé des patients. Dans le cas de patients à risque de dépendance, on devrait réserver les opioïdes aux douleurs nociceptives ou neuropathiques bien définies qui n’ont pas répondu aux traitements de première intention. Il faut procéder lentement au titrage des opioïdes, avec des dispensations fréquentes et une étroite surveillance pour dépister tout signe d’usage abusif. Une dépendance aux opioïdes suspectée est prise en charge au moyen d’une thérapie structurée aux opioïdes, d’un traitement à la méthadone ou à la buprénorphine ou encore d’un traitement fondé sur l’abstinence. Les patients souffrant de troubles de l’humeur ou d’anxiété ont tendance à avoir une réponse analgésique atténuée aux opioïdes, sont à risque plus élevé d’usage abusif et prennent souvent des sédatifs qui interagissent défavorablement avec les opioïdes. Il faut prendre des précautions semblables à celles utilisées avec d’autres patients à risque élevé. Il faut faire un sevrage progressif si la douleur du patient demeure sévère même avec un essai adéquat de thérapie aux opioïdes. Chez les personnes âgées, la s

  13. L'astronomie des Anciens

    NASA Astrophysics Data System (ADS)

    Nazé, Yaël

    2009-04-01

    Quelle que soit la civilisation à laquelle il appartient, l'être humain cherche dans le ciel des réponses aux questions qu'il se pose sur son origine, son avenir et sa finalité. Le premier mérite de ce livre est de nous rappeler que l'astronomie a commencé ainsi à travers les mythes célestes imaginés par les Anciens pour expliquer l'ordre du monde et la place qu'ils y occupaient. Mais les savoirs astronomiques passés étaient loin d'être négligeables et certainement pas limités aux seuls travaux des Grecs : c'est ce que l'auteur montre à travers une passionnante enquête, de Stonehenge à Gizeh en passant par Pékin et Mexico, fondée sur l'étude des monuments anciens et des sources écrites encore accessibles. Les tablettes mésopotamiennes, les annales chinoises, les chroniques médiévales, etc. sont en outre d'une singulière utilité pour les astronomes modernes : comment sinon remonter aux variations de la durée du jour au cours des siècles, ou percer la nature de l'explosion qui a frappé tant d'observateurs en 1054 ? Ce livre offre un voyage magnifiquement illustré à travers les âges, entre astronomie et archéologie.

  14. Effects of Zinc Chelators on Aflatoxin Production in Aspergillus parasiticus

    PubMed Central

    Wee, Josephine; Day, Devin M.; Linz, John E.

    2016-01-01

    Zinc concentrations strongly influence aflatoxin accumulation in laboratory media and in food and feed crops. The presence of zinc stimulates aflatoxin production, and the absence of zinc impedes toxin production. Initial studies that suggested a link between zinc and aflatoxin biosynthesis were presented in the 1970s. In the present study, we utilized two zinc chelators, N,N,N′,N′-tetrakis (2-pyridylmethyl) ethane-1,2-diamine (TPEN) and 2,3-dimercapto-1-propanesulfonic acid (DMPS) to explore the effect of zinc limitation on aflatoxin synthesis in Aspergillus parasiticus. TPEN but not DMPS decreased aflatoxin biosynthesis up to six-fold depending on whether A. parasiticus was grown on rich or minimal medium. Although we observed significant inhibition of aflatoxin production by TPEN, no detectable changes were observed in expression levels of the aflatoxin pathway gene ver-1 and the zinc binuclear cluster transcription factor, AflR. Treatment of growing A. parasiticus solid culture with a fluorescent zinc probe demonstrated an increase in intracellular zinc levels assessed by increases in fluorescent intensity of cultures treated with TPEN compared to controls. These data suggest that TPEN binds to cytoplasmic zinc therefore limiting fungal access to zinc. To investigate the efficacy of TPEN on food and feed crops, we found that TPEN effectively decreases aflatoxin accumulation on peanut medium but not in a sunflower seeds-derived medium. From an application perspective, these data provide the basis for biological differences that exist in the efficacy of different zinc chelators in various food and feed crops frequently contaminated by aflatoxin. PMID:27271668

  15. Repletion of Zinc and Iron Deficiencies Improves Cognition of Premenopausal Women.

    DTIC Science & Technology

    1997-10-01

    to our earlier observations in premenopausal women (1, 13) and are consistent with the fact that many premenopausal women select diets that are low...women: associations of diet with serum ferritin and plasma zinc disappearance, and of serum ferritin with plasma zinc and plasma zinc disappearance...women: Associations of diet with serum ferritin and plasma zinc disappearance and of serum ferritin with plasma zinc and plasma zinc disappearance. J

  16. Implementation Cryptography Data Encryption Standard (DES) and Triple Data Encryption Standard (3DES) Method in Communication System Based Near Field Communication (NFC)

    NASA Astrophysics Data System (ADS)

    Ratnadewi; Pramono Adhie, Roy; Hutama, Yonatan; Saleh Ahmar, A.; Setiawan, M. I.

    2018-01-01

    Cryptography is a method used to create secure communication by manipulating sent messages during the communication occurred so only intended party that can know the content of that messages. Some of the most commonly used cryptography methods to protect sent messages, especially in the form of text, are DES and 3DES cryptography method. This research will explain the DES and 3DES cryptography method and its use for stored data security in smart cards that working in the NFC-based communication system. Several things that will be explained in this research is the ways of working of DES and 3DES cryptography method in doing the protection process of a data and software engineering through the creation of application using C++ programming language to realize and test the performance of DES and 3DES cryptography method in encrypted data writing process to smart cards and decrypted data reading process from smart cards. The execution time of the entering and the reading process data using a smart card DES cryptography method is faster than using 3DES cryptography.

  17. Zinc supplementation for tinnitus.

    PubMed

    Person, Osmar C; Puga, Maria Es; da Silva, Edina Mk; Torloni, Maria R

    2016-11-23

    Tinnitus is the perception of sound without external acoustic stimuli. Patients with severe tinnitus may have physical and psychological complaints and their tinnitus can cause deterioration in their quality of life. At present no specific therapy for tinnitus has been found to be satisfactory in all patients. In recent decades, a number of reports have suggested that oral zinc supplementation may be effective in the management of tinnitus. Since zinc has a role in cochlear physiology and in the synapses of the auditory system, there is a plausible mechanism of action for this treatment. To evaluate the effectiveness and safety of oral zinc supplementation in the management of patients with tinnitus. The Cochrane ENT Information Specialist searched the ENT Trials Register; Central Register of Controlled Trials (CENTRAL 2016, Issue 6); PubMed; EMBASE; CINAHL; Web of Science; ClinicalTrials.gov; ICTRP and additional sources for published and unpublished trials. The date of the search was 14 July 2016. Randomised controlled trials comparing zinc supplementation versus placebo in adults (18 years and over) with tinnitus. We used the standard methodological procedures recommended by Cochrane. Our primary outcome measures were improvement in tinnitus severity and disability, measured by a validated tinnitus-specific questionnaire, and adverse effects. Secondary outcomes were quality of life, change in socioeconomic impact associated with work, change in anxiety and depression disorders, change in psychoacoustic parameters, change in tinnitus loudness, change in overall severity of tinnitus and change in thresholds on pure tone audiometry. We used GRADE to assess the quality of the evidence for each outcome; this is indicated in italics. We included three trials involving a total of 209 participants. The studies were at moderate to high risk of bias. All included studies had differences in participant selection criteria, length of follow-up and outcome measurement

  18. Zinc decreases C-reactive protein, lipid peroxidation, and inflammatory cytokines in elderly subjects: a potential implication of zinc as an atheroprotective agent123

    PubMed Central

    Bao, Bin; Prasad, Ananda S; Beck, Frances WJ; Fitzgerald, James T; Snell, Diane; Bao, Ginny W; Singh, Tapinder; Cardozo, Lavoisier J

    2010-01-01

    Background: Chronic inflammation and oxidative stress are common risk factors for atherosclerosis. Zinc is an essential micronutrient that can function as an antiinflammatory and antioxidative agent, and as such, it may have atheroprotective properties. Objective: We hypothesized that zinc down-regulates the production of atherosclerosis-related cytokines/molecules in humans. Design: To examine these effects, we conducted a randomized, double-blinded, placebo trial of zinc supplementation in elderly subjects. We recruited 40 healthy elderly subjects (aged 56–83 y) and randomly assigned them to 2 groups. One group was given an oral dose of 45 mg zinc/d as a gluconate for 6 mo. The other group was given a placebo. Cell culture models were conducted to study the mechanism of zinc as an atheroprotective agent. Results: After 6 mo of supplementation, the intake of zinc, compared with intake of placebo, increased the concentrations of plasma zinc and decreased the concentrations of plasma high-sensitivity C-reactive protein (hsCRP), interleukin (IL)-6, macrophage chemoattractant protein 1 (MCP-1), vascular cell adhesion molecule 1 (VCAM-1), secretory phospholipase A2, and malondialdehyde and hydroxyalkenals (MDA+HAE) in elderly subjects. Regression analysis showed that changes in concentrations of plasma zinc were inversely associated with changes in concentrations of plasma hsCRP, MCP-1, VCAM-1, and MDA+HAE after 6 mo of supplementation. In cell culture studies, we showed that zinc decreased the generation of tumor necrosis factor-α, IL-1β, VCAM-1, and MDA+HAE and the activation of nuclear transcription factor κB and increased antiinflammatory proteins A20 and peroxisome proliferator–activated receptor-α in human monocytic leukemia THP-1 cells and human aortic endothelial cells compared with zinc-deficient cells. Conclusion: These findings suggest that zinc may have a protective effect in atherosclerosis because of its antiinflammatory and antioxidant functions

  19. Targeted Zinc Delivery: A Novel Treatment for Prostate Cancer

    DTIC Science & Technology

    2010-06-01

    aconitase, which normally functions to oxidize citrate during the Krebs cycle . Because citrate is a principle component of seminal fluid, prostate...tissue, likely due to the metabolic effects of zinc in the Krebs cycle . That is, because zinc inhibits m- aconitase, loss of zinc allows for greater...secretory cells do not complete the oxidation of citrate in the mitochondria and the zinc-mediated inhibition of m-aconitase is crucial for the

  20. Improved synthesis of fine zinc borate particles using seed crystals

    NASA Astrophysics Data System (ADS)

    Gürhan, Deniz; Çakal, Gaye Ö.; Eroğlu, İnci; Özkar, Saim

    2009-03-01

    Zinc borate is a flame retardant additive used in polymers, wood applications and textile products. There are different types of zinc borate having different chemical compositions and structures. In this study, the production of zinc borate having the molecular formula of 2ZnO·3B 2O 3·3.5H 2O was reexamined by studying the effects of reaction parameters on the properties of product as well as the reaction kinetics. Production of zinc borate from the reaction of boric acid and zinc oxide in the presence of seed crystals was performed in a continuously stirred, temperature-controlled batch reactor having a volume of 1.5 L. Samples taken in regular time intervals during the experiments were analyzed for the concentration of zinc oxide and boron oxide in the solid as well as for the conversion of zinc oxide to zinc borate versus time. The zinc borate production reaction was fit to the logistic model. The reaction rate, reaction completion time, composition and particle size distribution of zinc borate product were determined by varying the following parameters: the boric acid to zinc oxide ratio (H 3BO 3:ZnO=3:1, 3.5:1, 5:1 and 7:1), the particle size of zinc oxide (10 and 25 μm), stirring rate (275, 400, 800 and 1600 rpm), temperature (75, 85 and 95 °C) and the size of seed crystals (10 and 2 μm). The products were also analyzed for particle size distribution. The experimental results showed that the reaction rate increases with the increase in H 3BO 3:ZnO ratio, particle size of zinc oxide, stirring rate and temperature. Concomitantly, the reaction completion time is decreased by increasing the H 3BO 3:ZnO ratio, stirring rate and temperature. The average particle sizes of the zinc borate products are in the range 4.3-16.6 μm (wet dispersion analysis).

  1. Directed spatial organization of zinc oxide nanostructures

    DOEpatents

    Hsu, Julia [Albuquerque, NM; Liu, Jun [Richland, WA

    2009-02-17

    A method for controllably forming zinc oxide nanostructures on a surface via an organic template, which is formed using a stamp prepared from pre-defined relief structures, inking the stamp with a solution comprising self-assembled monolayer (SAM) molecules, contacting the stamp to the surface, such as Ag sputtered on Si, and immersing the surface with the patterned SAM molecules with a zinc-containing solution with pH control to form zinc oxide nanostructures on the bare Ag surface.

  2. Zinc-based electrolyte compositions, and related electrochemical processes and articles

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Kniajanski, Sergei; Soloveichik, Grigorii Lev

    An aqueous electrolyte composition is described, including a zinc salt based on zinc acetate or zinc glocolate. The saturation concentration of zinc in the electrolyte composition is in the range of about 2.5M to about 3.5M. The composition also contains at least one salt of a monovalent cation. The molar ratio of zinc to the monovalent cation is about 1:2. An aqueous zinc electroplating bath, containing the aqueous electrolyte composition, is also disclosed, along with a method for the electrochemical deposition of zinc onto a substrate surface, using the electroplating bath. Related flow batteries are also described, including a catholyte,more » as well as an anolyte based on the aqueous electrolyte composition, with a membrane between the catholyte and the anolyte.« less

  3. Potential ecological risk assessment and predicting zinc accumulation in soils.

    PubMed

    Baran, Agnieszka; Wieczorek, Jerzy; Mazurek, Ryszard; Urbański, Krzysztof; Klimkowicz-Pawlas, Agnieszka

    2018-02-01

    The aims of this study were to investigate zinc content in the studied soils; evaluate the efficiency of geostatistics in presenting spatial variability of zinc in the soils; assess bioavailable forms of zinc in the soils and to assess soil-zinc binding ability; and to estimate the potential ecological risk of zinc in soils. The study was conducted in southern Poland, in the Malopolska Province. This area is characterized by a great diversity of geological structures and types of land use and intensity of industrial development. The zinc content was affected by soil factors, and the type of land use (arable lands, grasslands, forests, wastelands). A total of 320 soil samples were characterized in terms of physicochemical properties (texture, pH, organic C content, total and available Zn content). Based on the obtained data, assessment of the ecological risk of zinc was conducted using two methods: potential ecological risk index and hazard quotient. Total Zn content in the soils ranged from 8.27 to 7221 mg kg -1 d.m. Based on the surface semivariograms, the highest variability of zinc in the soils was observed from northwest to southeast. The point sources of Zn contamination were located in the northwestern part of the area, near the mining-metallurgical activity involving processing of zinc and lead ores. These findings were confirmed by the arrangement of semivariogram surfaces and bivariate Moran's correlation coefficients. The content of bioavailable forms of zinc was between 0.05 and 46.19 mg kg -1 d.m. (0.01 mol dm -3 CaCl 2 ), and between 0.03 and 71.54 mg kg -1 d.m. (1 mol dm -3 NH 4 NO 3 ). Forest soils had the highest zinc solubility, followed by arable land, grassland and wasteland. PCA showed that organic C was the key factor to control bioavailability of zinc in the soils. The extreme, very high and medium zinc accumulation was found in 69% of studied soils. There is no ecological risk of zinc to living organisms in the study area, and in 90

  4. Zinc use efficiency is enhanced in wheat through nanofertilization.

    PubMed

    Dapkekar, Ashwin; Deshpande, Paresh; Oak, Manoj D; Paknikar, Kishore M; Rajwade, Jyutika M

    2018-05-01

    Ferti-fortification of wheat with zinc, an essential micronutrient is one of the strategies for combating 'hidden hunger' in a large proportion of people all over the world. During fertilization, application of large quantities of micronutrients often results in nutrient wastage and subsequent environmental pollution. Here, we report zinc complexed chitosan nanoparticles (Zn-CNP) for ferti-fortification of durum wheat in field-scale experiments. The efficacy of Zn-CNP was assessed vis-à-vis conventionally applied ZnSO 4 (0.2%; 400 mgL -1 zinc) in two durum wheat genotypes (MACS 3125, an indigenous high yielding genotype and UC 1114, a genotype containing the Gpc-B1gene). The observed grain zinc enrichment using Zn-CNP nanocarrier (~36%) and conventional ZnSO 4 (~50%) were comparable, despite 10 folds less zinc (40 mgL -1 ) used in the former. Nanofertilizer application increased grain zinc content without affecting grain yield, protein content, spikelets per spike, thousand kernel weight, etc. Grain zinc enrichment observed in the four-year field trials on plots with varying soil zinc content was consistent, proving the utility of Zn-CNP as a novel nanofertilizer which enhanced fertilizer use efficiency. Our work describes a new paradigm in micronutrient fortification, viz. 'use nanofertilizers at the right place, right time and in right doses'.

  5. 21 CFR 73.1991 - Zinc oxide.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 1 2011-04-01 2011-04-01 false Zinc oxide. 73.1991 Section 73.1991 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL LISTING OF COLOR... coloring externally applied drugs. (b) Specifications. Zinc oxide shall conform to the following...

  6. 21 CFR 73.2991 - Zinc oxide.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... ADDITIVES EXEMPT FROM CERTIFICATION Cosmetics § 73.2991 Zinc oxide. (a) Identity and specifications. The... (a)(1) and (b). (b) Uses and restrictions. Zinc oxide may be safely used in cosmetics, including cosmetics intended for use in the area of the eye, in amounts consistent with good manufacturing practice...

  7. Coupled Experimental and Theoretical Investigations of Instability, Chaos and Turbulence in an Axisymmetric Jet Flow

    DTIC Science & Technology

    1990-07-01

    performed using two of the available methods, due respectively to Wolf et al. 8, and...FiueS1 270 Paper in progress to be submitted to: Phys. Fluids. ECOLE CENTRALE DES ARTS ET MANUFACTURES RAPPORT DE STAGE DE FIN D’ETUDES EXCITATION D’UN JET...disposition et de la souplesse dont ii a fait preuve. Je tiens dgalement & remercier tout particuliirement Patrick Reisenthel de toute 1’attention et

  8. Ground and excited states of zinc phthalocyanine, zinc tetrabenzoporphyrin, and azaporphyrin analogs using DFT and TDDFT with Franck-Condon analysis

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Theisen, Rebekah F., E-mail: rtheisen@asu.edu; Huang, Liang; Fleetham, Tyler

    2015-03-07

    The electronic structure of eight zinc-centered porphyrin macrocyclic molecules are investigated using density functional theory for ground-state properties, time-dependent density functional theory (TDDFT) for excited states, and Franck-Condon (FC) analysis for further characterization of the UV-vis spectrum. Symmetry breaking was utilized to find the lowest energy of the excited states for many states in the spectra. To confirm the theoretical modeling, the spectroscopic result from zinc phthalocyanine (ZnPc) is used to compare to the TDDFT and FC result. After confirmation of the modeling, five more planar molecules are investigated: zinc tetrabenzoporphyrin (ZnTBP), zinc tetrabenzomonoazaporphyrin (ZnTBMAP), zinc tetrabenzocisdiazaporphyrin (ZnTBcisDAP), zinc tetrabenzotransdiazaporphyrinmore » (ZnTBtransDAP), and zinc tetrabenzotriazaporphyrin (ZnTBTrAP). The two latter molecules are then compared to their phenylated sister molecules: zinc monophenyltetrabenzotriazaporphyrin (ZnMPTBTrAP) and zinc diphenyltetrabenzotransdiazaporphyrin (ZnDPTBtransDAP). The spectroscopic results from the synthesis of ZnMPTBTrAP and ZnDPTBtransDAP are then compared to their theoretical models and non-phenylated pairs. While the Franck-Condon results were not as illuminating for every B-band, the Q-band results were successful in all eight molecules, with a considerable amount of spectral analysis in the range of interest between 300 and 750 nm. The π-π{sup ∗} transitions are evident in the results for all of the Q bands, while satellite vibrations are also visible in the spectra. In particular, this investigation finds that, while ZnPc has a D{sub 4h} symmetry at ground state, a C{sub 4v} symmetry is predicted in the excited-state Q band region. The theoretical results for ZnPc found an excitation energy at the Q-band 0-0 transition of 1.88 eV in vacuum, which is in remarkable agreement with published gas-phase spectroscopy, as well as our own results of ZnPc in solution

  9. Soybean extracts increase cell surface ZIP4 abundance and cellular zinc levels: a potential novel strategy to enhance zinc absorption by ZIP4 targeting.

    PubMed

    Hashimoto, Ayako; Ohkura, Katsuma; Takahashi, Masakazu; Kizu, Kumiko; Narita, Hiroshi; Enomoto, Shuichi; Miyamae, Yusaku; Masuda, Seiji; Nagao, Masaya; Irie, Kazuhiro; Ohigashi, Hajime; Andrews, Glen K; Kambe, Taiho

    2015-12-01

    Dietary zinc deficiency puts human health at risk, so we explored strategies for enhancing zinc absorption. In the small intestine, the zinc transporter ZIP4 functions as an essential component of zinc absorption. Overexpression of ZIP4 protein increases zinc uptake and thereby cellular zinc levels, suggesting that food components with the ability to increase ZIP4 could potentially enhance zinc absorption via the intestine. In the present study, we used mouse Hepa cells, which regulate mouse Zip4 (mZip4) in a manner indistinguishable from that in intestinal enterocytes, to screen for suitable food components that can increase the abundance of ZIP4. Using this ZIP4-targeting strategy, two such soybean extracts were identified that were specifically able to decrease mZip4 endocytosis in response to zinc. These soybean extracts also effectively increased the abundance of apically localized mZip4 in transfected polarized Caco2 and Madin-Darby canine kidney cells and, moreover, two apically localized mZip4 acrodermatitis enteropathica mutants. Soybean components were purified from one extract and soyasaponin Bb was identified as an active component that increased both mZip4 protein abundance and zinc levels in Hepa cells. Finally, we confirmed that soyasaponin Bb is capable of enhancing cell surface endogenous human ZIP4 in human cells. Our results suggest that ZIP4 targeting may represent a new strategy to improve zinc absorption in humans. © 2015 Authors; published by Portland Press Limited.

  10. Mechanically refuelable zinc/air electric vehicle cells

    NASA Astrophysics Data System (ADS)

    Noring, J.; Gordon, S.; Maimoni, A.; Spragge, M.; Cooper, J. F.

    1992-12-01

    Refuelable zinc/air batteries have long been considered for motive as well as stationary power because of a combination of high specific energy, low initial cost, and the possibility of mechanical recharge by electrolyte exchange and additions of metallic zinc. In this context, advanced slurry batteries, stationary packed bed cells, and batteries offering replaceable cassettes have been reported recently. The authors are developing self-feeding, particulate-zinc/air batteries for electric vehicle applications. Emissionless vehicle legislation in California motivated efforts to consider a new approach to providing an electric vehicle with long range (400 km), rapid refueling (10 minutes) and highway safe acceleration - factors which define the essential functions of common automobiles. Such an electric vehicle would not compete with emerging secondary battery vehicles in specialized applications (commuting vehicles, delivery trucks). Rather, different markets would be sought where long range or rapid range extension are important. Examples are: taxis, continuous-duty fork-lift trucks and shuttle busses, and general purpose automobiles having modest acceleration capabilities. In the long range, a mature fleet would best use regional plants to efficiently recover zinc from battery reaction products. One option would be to use chemical/thermal reduction to recover the zinc. The work described focuses on development of battery configurations which efficiently and completely consume zinc particles, without clogging or changing discharge characteristics.

  11. Response of hippocampal mossy fiber zinc to excessive glutamate release.

    PubMed

    Takeda, Atsushi; Minami, Akira; Sakurada, Naomi; Nakajima, Satoko; Oku, Naoto

    2007-01-01

    The response of hippocampal mossy fiber zinc to excessive glutamate release was examined to understand the role of the zinc in excessive excitation in the hippocampus. Extracellular zinc and glutamate concentrations during excessive stimulation with high K(+) were compared between the hippocampal CA3 and CA1 by the in vivo microdialysis. Zinc concentration in the CA3 was more increased than that in the CA1, while glutamate concentration in the CA3 was less increased than that in the CA1. It is likely that more increase in extracellular zinc is linked with less increase in extracellular glutamate in the CA3. To see zinc action in mossy fiber synapses during excessive excitation, furthermore, 1mM glutamate was regionally delivered to the stratum lucidum in the presence of zinc or CaEDTA, a membrane-impermeable zinc chelator, and intracellular calcium signal was measured in the CA3 pyramidal cell layer. The persistent increase in calcium signal during stimulation with glutamate was significantly attenuated in the presence of 100 microM zinc, while significantly enhanced in the presence of 1mM CaEDTA. These results suggest that zinc released from mossy fibers attenuates the increase in intracellular calcium signal in mossy fiber synapses and postsynaptic CA3 neurons after excessive inputs to dentate granular cells.

  12. X-ray absorption Studies of Zinc species in Centella asiatica

    NASA Astrophysics Data System (ADS)

    Dehipawala, Sunil; Cheung, Tak; Hogan, Clayton; Agoudavi, Yao; Dehipawala, Sumudu

    2013-03-01

    Zinc is a very important mineral present in a variety of vegetables. It is an essential element in cellular metabolism and several bodily functions. We used X-ray fluorescence, and X-ray Absorption near Edge structure(XANES) to study the amount of zinc present in several leafy vegetables as well as its chemical environment within the plant. Main absorption edge position of XANES is sensitive to the oxidation state of zinc and is useful when comparing the type of zinc present in different vegetables to the standard zinc present in supplements. Normalized main edge height is proportional to the amount of zinc present in the sample. Several leafy greens were used in this study, such as Spinacia oleracea, Basella alba, Brassica oleracea, Cardiospermum halicacabumand Centella asiatica. All of these plant leaves contained approximately the same amount of zinc in the leaf portion of the plant and a slightly lower amount in the stems, except Centella asiatica. Both leaves and stems of the plant Centella asiatica contained nearly two times the zinc compared to other plants. Further investigation of zinc's chemical environment within Centella asiatica could lead to a much more efficient dietary consumption of zinc. Use of the National Synchrotron Light Source, Brookhaven National Laboratory, was supported by the U.S. Department of Energy, Office of Science, Office of Basic Energy Sciences, under Contract No. DE-AC02-98CH10886

  13. Effects of surface hydroxylation on adhesion at zinc/silica interfaces.

    PubMed

    Le, Ha-Linh Thi; Goniakowski, Jacek; Noguera, Claudine; Koltsov, Alexey; Mataigne, Jean-Michel

    2018-06-06

    The weak interaction between zinc and silica is responsible for the poor performance of anti-corrosive galvanic zinc coatings on modern advanced high-strength steels, which are fundamental in the automotive industry, and important for rail transport, shipbuilding, and aerospace. With the goal of identifying possible methods for its improvement, we report an ab initio study of the effect of surface hydroxylation on the adhesion characteristics of model zinc/β-cristobalite interfaces, representative of various surface hydroxylation/hydrogenation conditions. We show that surface silanols resulting from dissociative water adsorption at the most stable stoichiometric (001) and (111) surfaces prevent strong zinc-silica interactions. However, dehydrogenation of such interfaces produces oxygen-rich zinc/silica contacts with excellent adhesion characteristics. These are due to partial zinc oxidation and the formation of strong iono-covalent Zn-O bonds between zinc atoms and the under-coordinated excess anions, remnant of the hydroxylation layer. Interestingly, these interfaces appear as the most thermodynamically stable in a wide range of realistic oxygen-rich and hydrogen-lean environments. We also point out that the partial oxidation of zinc atoms in direct contact with the oxide substrate may somewhat weaken the cohesion in the zinc deposit itself. This fundamental analysis of the microscopic mechanisms responsible for the improved zinc wetting on pre-hydroxylated silica substrates provides useful guidelines towards practical attempts to improve adhesion.

  14. Electrochemical synthesis and characterization of zinc oxalate nanoparticles

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Shamsipur, Mojtaba, E-mail: mshamsipur@yahoo.com; Roushani, Mahmoud; Department of Chemistry, Ilam University, Ilam

    2013-03-15

    Highlights: ► Synthesis of zinc oxalate nanoparticles via electrolysis of a zinc plate anode in sodium oxalate solutions. ► Design of a Taguchi orthogonal array to identify the optimal experimental conditions. ► Controlling the size and shape of particles via applied voltage and oxalate concentration. ► Characterization of zinc oxalate nanoparticles by SEM, UV–vis, FT-IR and TG–DTA. - Abstract: A rapid, clean and simple electrodeposition method was designed for the synthesis of zinc oxalate nanoparticles. Zinc oxalate nanoparticles in different size and shapes were electrodeposited by electrolysis of a zinc plate anode in sodium oxalate aqueous solutions. It was foundmore » that the size and shape of the product could be tuned by electrolysis voltage, oxalate ion concentration, and stirring rate of electrolyte solution. A Taguchi orthogonal array design was designed to identify the optimal experimental conditions. The morphological characterization of the product was carried out by scanning electron microscopy. UV–vis and FT-IR spectroscopies were also used to characterize the electrodeposited nanoparticles. The TG–DTA studies of the nanoparticles indicated that the main thermal degradation occurs in two steps over a temperature range of 350–430 °C. In contrast to the existing methods, the present study describes a process which can be easily scaled up for the production of nano-sized zinc oxalate powder.« less

  15. Selection of organic acid leaching reagent for recovery of zinc and manganese from zinc-carbon and alkaline spent batteries

    NASA Astrophysics Data System (ADS)

    Yuliusman; Amiliana, R. A.; Wulandari, P. T.; Ramadhan, I. T.; Kusumadewi, F. A.

    2018-03-01

    Zinc-carbon and alkaline batteries are often used in electronic equipment that requires small quantities of power. The waste from these batteries contains valuable metals, such as zinc and manganese, that are needed in many industries and can pollute the environment if not treated properly. This paper concerns the recovery of zinc and manganese metals from zinc-carbon and alkaline spent batteries with leaching method and using organic acid as the environmental friendly leaching reagent. Three different organic acids, namely citric acid, malic acid and aspartic acid, were used as leaching reagents and compared with sulfuric acid as non-organic acid reagents that often used for leaching. The presence of hydrogen peroxide as manganese reducers was investigated for both organic and non-organic leaching reagents. The result showed that citric acid can recover 64.37% Zinc and 51.32% Manganese, while malic acid and aspartic acid could recover less than these. Hydrogen peroxide gave the significant effect for leaching manganese with non-organic acid, but not with organic acid.

  16. 21 CFR 182.8997 - Zinc sulfate.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Zinc sulfate. 182.8997 Section 182.8997 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN CONSUMPTION (CONTINUED) SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients § 182.8997 Zinc sulfate. (a) Product...

  17. 21 CFR 182.8991 - Zinc oxide.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Zinc oxide. 182.8991 Section 182.8991 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN CONSUMPTION (CONTINUED) SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients § 182.8991 Zinc oxide. (a) Product...

  18. 21 CFR 182.8997 - Zinc sulfate.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Zinc sulfate. 182.8997 Section 182.8997 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN CONSUMPTION (CONTINUED) SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients § 182.8997 Zinc sulfate. (a) Product...

  19. 21 CFR 182.8994 - Zinc stearate.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Zinc stearate. 182.8994 Section 182.8994 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN CONSUMPTION (CONTINUED) SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients § 182.8994 Zinc stearate. (a...

  20. 21 CFR 182.8994 - Zinc stearate.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Zinc stearate. 182.8994 Section 182.8994 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN CONSUMPTION (CONTINUED) SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients § 182.8994 Zinc stearate. (a...

  1. 21 CFR 182.8985 - Zinc chloride.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Zinc chloride. 182.8985 Section 182.8985 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN CONSUMPTION (CONTINUED) SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients § 182.8985 Zinc chloride. (a...

  2. 21 CFR 182.8991 - Zinc oxide.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Zinc oxide. 182.8991 Section 182.8991 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN CONSUMPTION (CONTINUED) SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients § 182.8991 Zinc oxide. (a) Product...

  3. 21 CFR 182.8988 - Zinc gluconate.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Zinc gluconate. 182.8988 Section 182.8988 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN CONSUMPTION (CONTINUED) SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients § 182.8988 Zinc gluconate. (a...

  4. 21 CFR 182.8988 - Zinc gluconate.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 21 Food and Drugs 3 2013-04-01 2013-04-01 false Zinc gluconate. 182.8988 Section 182.8988 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN CONSUMPTION (CONTINUED) SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients § 182.8988 Zinc gluconate. (a...

  5. 21 CFR 182.8985 - Zinc chloride.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 21 Food and Drugs 3 2012-04-01 2012-04-01 false Zinc chloride. 182.8985 Section 182.8985 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES (CONTINUED) FOOD FOR HUMAN CONSUMPTION (CONTINUED) SUBSTANCES GENERALLY RECOGNIZED AS SAFE Nutrients § 182.8985 Zinc chloride. (a...

  6. Zinc cyanide

    Integrated Risk Information System (IRIS)

    Zinc cyanide ; CASRN 557 - 21 - 1 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarcinogenic Effe

  7. Zinc phosphide

    Integrated Risk Information System (IRIS)

    Zinc phoshide ; CASRN 1314 - 84 - 7 Human health assessment information on a chemical substance is included in the IRIS database only after a comprehensive review of toxicity data , as outlined in the IRIS assessment development process . Sections I ( Health Hazard Assessments for Noncarcinogenic Ef

  8. Relations de Dispersion et Diffusion des Glueballs et des Mesons dans la Theorie de Jauge U(1)(2+1) Compacte

    NASA Astrophysics Data System (ADS)

    Ahmed, Chaara El Mouez

    Nous avons etudie les relations de dispersion et la diffusion des glueballs et des mesons dans le modele U(1)_{2+1} compact. Ce modele a ete souvent utilise comme un simple modele de la chromodynamique quantique (QCD), parce qu'il possede le confinement ainsi que les etats de glueballs. Par contre, sa structure mathematique est beaucoup plus simple que la QCD. Notre methode consiste a diagonaliser l'Hamiltonien de ce modele dans une base appropriee de graphes et sur reseau impulsion, afin de generer les relations de dispersion des glueballs et des mesons. Pour la diffusion, nous avons utilise la methode dependante du temps pour calculer la matrice S et la section efficace de diffusion des glueballs et des mesons. Les divers resultats obtenus semblent etre en accord avec les travaux anterieurs de Hakim, Alessandrini et al., Irving et al., qui eux, utilisent plutot la theorie des perturbations en couplage fort, et travaillent sur un reseau espace-temps.

  9. Serum zinc concentrations: contamination from laboratory equipment.

    PubMed

    Ralstin, J O; Schneider, P J; Blackstone, L; Ruberg, R L

    1979-01-01

    The following experiment was designed because of high serum zinc reported in patients who were reciving total parenteral nutrition (TPN) concentrations. Blood samples were collected, divided into 3 containers: a clean glass control test tube, a vacuum collecting tube with a rubber stopper, and paraffin clot activator. It was found that compared to glass control tubes, vacuum collection with rubber stoppers contributed an average of 76 +/- 14 microgram/dl of zinc as contaminants. Moreover, tubes with a rubber stopper and clot activator contributed 198 +/- 42 microgram/dl of zinc as contaminants. It is concluded that care must be used to avoid trace element contaminants when plasma zinc concentrations are analyzed. Without proper methodology, including selection of the container in which the sample is taken, erroneous results will be reported.

  10. The significance of the source of zinc and its anti-VSC effect.

    PubMed

    Rölla, G; Jonski, G; Young, A

    2002-06-01

    The anti-VSC (volatile sulphur compounds) effect of zinc is known to be associated with free zinc ions. To examine whether zinc salts with low stability constants were more suitable as sources of zinc in zinc lozenges than zinc salts with high stability constants. The former provide free zinc ions upon dissolution in water, whereas the latter provide few such ions. Identical lozenges were produced which contained either zinc acetate, zinc gluconate (low stability constants), zinc citrate or amino-acid chelated zinc (extremely high stability constants). All the lozenges contained 0.1 per cent of zinc. A test panel of 10 volunteers used the different lozenges randomly. VSC were measured by GC. The lozenge with the highest stability constant was as effective as those with very low stability constants. The anti-VSC effect was thus not related to this constant. These findings may be explained by the possibility that alternative ligands with stronger affinity for zinc than the original ligands in the lozenges may be present in the oral cavity. An in vitro experiment indicated that the sulphide ion (S2-) may be such a ligand.

  11. Subacute Zinc Administration and L-NAME Caused an Increase of NO, Zinc, Lipoperoxidation, and Caspase-3 during a Cerebral Hypoxia-Ischemia Process in the Rat

    PubMed Central

    Blanco-Alvarez, Victor Manuel; Lopez-Moreno, Patricia; Soto-Rodriguez, Guadalupe; Martinez-Fong, Daniel; Rubio, Hector; Gonzalez-Barrios, Juan Antonio; Piña-Leyva, Celia; Torres-Soto, Maricela; Gomez-Villalobos, María de Jesus; Hernandez-Baltazar, Daniel; Eguibar, José Ramon; Ugarte, Araceli; Cebada, Jorge

    2013-01-01

    Zinc or L-NAME administration has been shown to be protector agents, decreasing oxidative stress and cell death. However, the treatment with zinc and L-NAME by intraperitoneal injection has not been studied. The aim of our work was to study the effect of zinc and L-NAME administration on nitrosative stress and cell death. Male Wistar rats were treated with ZnCl2 (2.5 mg/kg each 24 h, for 4 days) and N-ω-nitro-L-arginine-methyl ester (L-NAME, 10 mg/kg) on the day 5 (1 hour before a common carotid-artery occlusion (CCAO)). The temporoparietal cortex and hippocampus were dissected, and zinc, nitrites, and lipoperoxidation were assayed at different times. Cell death was assayed by histopathology using hematoxylin-eosin staining and caspase-3 active by immunostaining. The subacute administration of zinc before CCAO decreases the levels of zinc, nitrites, lipoperoxidation, and cell death in the late phase of the ischemia. L-NAME administration in the rats treated with zinc showed an increase of zinc levels in the early phase and increase of zinc, nitrites, and lipoperoxidation levels, cell death by necrosis, and the apoptosis in the late phase. These results suggest that the use of these two therapeutic strategies increased the injury caused by the CCAO, unlike the alone administration of zinc. PMID:23997853

  12. Evaluation d’une grille de supervision des laboratoires des leishmanioses cutanées au Maroc

    PubMed Central

    El Mansouri, Bouchra; Amarir, Fatima; Hajli, Yamina; Fellah, Hajiba; Sebti, Faiza; Delouane, Bouchra; Sadak, Abderrahim; Adlaoui, El Bachir; Rhajaoui, Mohammed

    2017-01-01

    Introduction Afin d’évaluer une grille de contrôle standardisée de laboratoire de diagnostic des leishmanioses, comme nouveau outil de supervision. Méthodes Un essai pilote a été pratiqué sur sept laboratoires provinciaux, appartenant à quatre provinces au Maroc, en suivant l’évolution de leurs performances tous les deux ans, entre l’année 2006 et 2014. Cette étude détaille la situation des laboratoires provinciaux avant et après la mise en œuvre de la grille de supervision. Au total vingt et une grille sont analysées. Résultats En 2006, les résultats ont montré clairement une insuffisance des performances des laboratoires: besoin en formation (41.6%), personnel pratiquant le prélèvement cutané (25%), pénurie en matériels et réactifs (65%), gestions documentaire et local non conformes (85%). Différentes actions correctives ont été menées par le Laboratoire National de Référence des Leishmanioses (LNRL) durant la période d’étude. En 2014, le LNRL a enregistré une nette amélioration des performances des laboratoires. Les besoins en matière de formation, qualité du prélèvement, dotation en matériels et réactifs ont été comblés et une coordination efficace s’est établie entre le LNRL et les laboratoires provinciaux. Conclusion Ceci montre l'efficacité de la grille comme outil de supervision de grande qualité, et comme pierre angulaire de tout progrès qui doit être obtenu dans les programmes de lutte contre les leishmanioses. PMID:29187922

  13. Identification et prise en charge des femmes ayant des antécédents familiaux de cancer du sein

    PubMed Central

    Heisey, Ruth; Carroll, June C.

    2016-01-01

    Résumé Objectif Résumer les meilleures données portant sur les stratégies d’identification et de prise en charge des femmes qui présentent des antécédents familiaux de cancer du sein. Sources d’information Une recherche a été effectuée sur PubMed à l’aide des mots-clés anglais suivants : breast cancer, guidelines, risk, family history, management et magnetic resonance imaging screening, entre 2000 et 2016. La plupart des données sont de niveau II. Message principal Une bonne anamnèse familiale est essentielle lors de l’évaluation du risque de cancer du sein afin d’identifier les femmes qui sont candidates à une recommandation en counseling génétique pour un éventuel test génétique. On peut sauver des vies en offrant aux femmes porteuses d’une mutation au gène BRCA des interventions chirurgicales de réduction des risques (mastectomie bilatérale prophylactique, salpingo-ovariectomie bilatérale). Il faut encourager toutes les femmes qui présentent des antécédents familiaux de cancer du sein à demeurer actives et à limiter leur consommation d’alcool à moins de 1 verre par jour; certaines femmes sont admissibles à la chimioprévention. Il faut offrir aux femmes dont le risque à vie de cancer du sein est de 20 à 25 % ou plus un dépistage poussé par imagerie par résonance magnétique en plus d’une mammographie. Conclusion Une vie saine et la chimioprévention (chez les candidates) pourraient réduire l’incidence du cancer du sein; le dépistage poussé pourrait entraîner une détection plus précoce. Le fait d’aiguiller des femmes porteuses d’une mutation au BRCA vers la chirurgie de réduction des risques sauve des vies. PMID:27737991

  14. 21 CFR 73.2991 - Zinc oxide.

    Code of Federal Regulations, 2011 CFR

    2011-04-01

    ... 21 Food and Drugs 1 2011-04-01 2011-04-01 false Zinc oxide. 73.2991 Section 73.2991 Food and Drugs FOOD AND DRUG ADMINISTRATION, DEPARTMENT OF HEALTH AND HUMAN SERVICES GENERAL LISTING OF COLOR... color additive zinc oxide shall conform in identity and specifications to the requirements of § 73.1991...

  15. Note des Éditeurs scientifiques

    NASA Astrophysics Data System (ADS)

    Averbuch, P.

    Cette série d'articles est une revue de résultats expérimentaux sur différents "fluides" moléculaires, dans lesquels la cohésion est due à des forces de Van der Waals et à des liaisons hydrogène, l'eau étant un de ces fluides. Ces résultats sont présentés de façon à justifier expérimentalement un modèle original, non extensif, des propriétés de ces fluides, et l'ensemble se présente sous la forme de trois articles décrivant le modèle, suivis chacun par un article le comparant aux résultats expérimentaux publiés par de nombreux auteurs. Le caractère non extensif des propriétés physiques des fluides est choquant, contraire à beaucoup d'idées établies, il semble n'avoir en sa faveur qu'un argument, la comparaison avec un nombre de résultats expérimentaux assez grand pour que l'effet du hasard soit difficilement soupçonnable. En particulier, les écarts entre des résultats de mesures faits par des auteurs différents dans des conditions différentes sont expliqués, le sérieux et la compétence des différents expérimentateurs ne sont plus mis en doute : mais l'interprétation de ces résultats avec un modèle extensif non adapté est seule mise en cause. Les modèles extensifs étant utilisés systématiquement, au delà des expériences de physiciens, dans les calculs d'ingénieurs, et dans la modélisation d'appareils qui fonctionnent et de phénomènes naturels observés par tout le monde, il fallait expliquer pourquoi on pouvait renoncer à l'extensivité. Les raisons du succès pratique des modèles extensifs sont données, d'abord dans le cas des nématiques, puis dans celui des liquides ordinaires, et c'est ce qui rend l'ensemble cohérent, tant avec les mesures physiques fines qu'avec les observations quotidiennes. Il n'en reste pas moins que si l'interprétation donnée dans cette série d'articles est généralisable, une justification théorique du modèle utilisé devient nécessaire. Pour ce qui est des propriétés d

  16. An EXAFS study of zinc coordination in microbial cells.

    PubMed

    Webb, S M; Gaillard, J F; Jackson, B E; Stahl, D A

    2001-03-01

    Five microbes were isolated from metal amended enrichment cultures derived from the sediments of a lake contaminated by a zinc smelter. Each of these organisms was grown in pure culture in the presence of zinc. Quick Extended X-ray Absorption Fine Structure (QEXAFS) spectroscopy was used to investigate the average coordination environment of the zinc associated with the microbial biomass. Fitting of the first coordination shell of zinc shows that significant differences exist for each microbial species examined. The coordination environment of zinc varies between sulfurs to six-fold nitrogen/oxygen. with two microbial strains showing mixed coordination shells. Further study is required in order to characterize these sites and their locations within the cell.

  17. Applications of Composite Materials in Helicopter Construction (Les Applications des Materiaux Composite dans la Construction des Helicopteres),

    DTIC Science & Technology

    1983-11-21

    TRANSLATION TITLE: APPLICATIONS OF COMPOSITE MATERIALS IN HELICOPTER CONSTRUCTION LES APPLICATIONS DES MATERTAUX COMWSITE DANS LA CONSTRUCTION DES...International Symposium on Design and Use of Kevlar in Aircraft, Geneva, 12 October 1982 [Beziac, Gilbert;* Les applications des mat6riaux composite...the pilot’s orders to the engine and the rotors. --Rear rotor Conventional or "faired propeller" type with its overall pitch control --Vibration

  18. Zinc-rich oysters as well as zinc-yeast- and astaxanthin-enriched food improved sleep efficiency and sleep onset in a randomized controlled trial of healthy individuals.

    PubMed

    Saito, Hitomi; Cherasse, Yoan; Suzuki, Rina; Mitarai, Makoto; Ueda, Fumitaka; Urade, Yoshihiro

    2017-05-01

    Zinc is an essential mineral that plays an important role in the body. We previously reported that orally feeding zinc-enriched yeast to mice induces nonrapid-eye-movement sleep. In addition, astaxanthin, an antioxidant abundant in seafood such as salmon and krill, is able to chelate minerals and may promote zinc absorption, which in return may also improve sleep. The purpose of our study was to examine the effect of zinc-rich and astaxanthin-containing food on sleep in humans. We conducted a randomized, double-blinded, placebo-controlled parallel group trial of 120 healthy subjects and recorded their night activity by actigraphy for 12 weeks. These subjects were divided into four groups: placebo, zinc-rich food, zinc-, and astaxanthin-rich food, and placebo supplemented with zinc-enriched yeast and astaxanthin oil. Compared with the placebo group, the zinc-rich food group efficiently decreased the time necessary to fall asleep and improved sleep efficiency, whereas the group that ingested zinc-enriched yeast and astaxanthin oil significantly improved the sleep onset latency. Actigraphic sleep monitoring demonstrated that eating zinc-rich food improved sleep onset latency as well as improved the sleep efficiency in healthy individuals. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Influence of zinc on the calcium carbonate biomineralization of Halomonas halophila

    PubMed Central

    2012-01-01

    Background The salt tolerance of halophilic bacteria make them promising candidates for technical applications, like isolation of salt tolerant enzymes or remediation of contaminated saline soils and waters. Furthermore, some halophilic bacteria synthesize inorganic solids resulting in organic–inorganic hybrids. This process is known as biomineralization, which is induced and/or controlled by the organism. The adaption of the soft and eco-friendly reaction conditions of this formation process to technical syntheses of inorganic nano materials is desirable. In addition, environmental contaminations can be entrapped in biomineralization products which facilitate the subsequent removal from waste waters. The moderately halophilic bacteria Halomonas halophila mineralize calcium carbonate in the calcite polymorph. The biomineralization process was investigated in the presence of zinc ions as a toxic model contaminant. In particular, the time course of the mineralization process and the influence of zinc on the mineralized inorganic materials have been focused in this study. Results H. halophila can adapt to zinc contaminated medium, maintaining the ability for biomineralization of calcium carbonate. Adapted cultures show only a low influence of zinc on the growth rate. In the time course of cultivation, zinc ions accumulated on the bacterial surface while the medium depleted in the zinc contamination. Intracellular zinc concentrations were below the detection limit, suggesting that zinc was mainly bound extracellular. Zinc ions influence the biomineralization process. In the presence of zinc, the polymorphs monohydrocalcite and vaterite were mineralized, instead of calcite which is synthesized in zinc-free medium. Conclusions We have demonstrated that the bacterial mineralization process can be influenced by zinc ions resulting in the modification of the synthesized calcium carbonate polymorph. In addition, the shape of the mineralized inorganic material is chancing

  20. Evaluation of the serum zinc level in adult patients with melasma: Is there a relationship with serum zinc deficiency and melasma?

    PubMed

    Rostami Mogaddam, Majid; Safavi Ardabili, Nastaran; Iranparvar Alamdari, Manouchehr; Maleki, Nasrollah; Aghabalaei Danesh, Maryam

    2017-11-12

    Melasma is a common acquired hypermelanosis of sun-exposed skin, particularly on the face, which presents as symmetric, light- to gray-brown-colored macules and patches. There are several studies of serum zinc levels in cutaneous disorders. So far, no studies have been carried out to assess the serum zinc level in patients with melasma. The aim of this study is to determine the serum zinc level in patients with melasma compared to healthy subjects. A total of 118 patients with melasma and 118 healthy controls were enrolled in this prospective cross-sectional study. The two groups were matched for age and sex. Atomic absorption spectrophotometry was used to measure serum zinc levels. The statistical analysis was performed using SPSS software. The mean serum level of zinc in melasma patients and controls was 77.4±23.2 μg/dL and 82.2±23.9 μg/dL, respectively (P-value=.0001). Serum zinc deficiency was found in 45.8% and 23.7% of melasma patients and control subjects, respectively. A positive family history of melasma in first-degree relatives was present in 46 (39%) of the cases, and a history of taking oral contraceptive pill was found in 95 (81%) of women with melasma. The aggravating factors for melasma were stated as: sun exposure (11.1%), pregnancy (15.3%), nutrition (2.5%), oral contraceptive pills (18.6%), and emotional stress (5.9%). The malar and centrofacial patterns were seen in 3.4% and 72% of cases, respectively, whereas 24.6% of the patients had both centrofacial distribution and malar distribution, and there was no patient with mandibular pattern. Among patients with melasma, 20.3% had thyroid dysfunction, while in the control subjects, 8.4% had thyroid dysfunction (P=.001). There is a significant relationship between low levels of zinc and melasma. Zinc deficiency may be involved in the pathogenesis of melasma. Also, treatment with oral zinc supplements can be tried in these patients to see the outcome. However, to make recommendations on