<?xml version="1.0" encoding="UTF-8"?><xml><records><record><source-app name="Biblio" version="7.x">Drupal-Biblio</source-app><ref-type>17</ref-type><contributors><authors><author><style face="normal" font="default" size="100%">Correia dos Santos, Margarida Maria</style></author><author><style face="normal" font="default" size="100%">Alves, Sheila</style></author><author><style face="normal" font="default" size="100%">de Lurdes Simões Gonçalves, Maria</style></author><author><style face="normal" font="default" size="100%">Correia dos Santos, Margarida Maria</style></author><author><style face="normal" font="default" size="100%">Alves, Sheila</style></author><author><style face="normal" font="default" size="100%">de Lurdes Simões Gonçalves, Maria</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">Kinetics and Mechanism of Ni(II) Chelation in Model and Real Solutions of Xylem Sap of Quercus ilex</style></title><secondary-title><style face="normal" font="default" size="100%">Electroanalysis</style></secondary-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">10</style></keyword><keyword><style  face="normal" font="default" size="100%">1002</style></keyword><keyword><style  face="normal" font="default" size="100%">200703972</style></keyword><keyword><style  face="normal" font="default" size="100%">Complexation</style></keyword><keyword><style  face="normal" font="default" size="100%">Cyclic voltammetry</style></keyword><keyword><style  face="normal" font="default" size="100%">doi</style></keyword><keyword><style  face="normal" font="default" size="100%">elan</style></keyword><keyword><style  face="normal" font="default" size="100%">Kinetics</style></keyword><keyword><style  face="normal" font="default" size="100%">Nickel</style></keyword><keyword><style  face="normal" font="default" size="100%">Quercus ilex</style></keyword><keyword><style  face="normal" font="default" size="100%">Xylem sap</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">2007</style></year></dates><publisher><style face="normal" font="default" size="100%">WILEY-VCH Verlag</style></publisher><volume><style face="normal" font="default" size="100%">19</style></volume><pages><style face="normal" font="default" size="100%">2351-2361</style></pages><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">The kinetics of formation and dissociation of Ni(II) complexes with oxalic and citric acids was studied by cyclic voltammetry in model solutions of xylem sap of Q. ilex (the dominant tree growing on serpentine soils of Northeast Portugal) using representative concentrations, pH and ionic strength. The role of magnesium on complex formation was analyzed from solutions where Mg is present at concentration levels found in the xylem sap of Q. ilex growing on both nonserpentine and serpentine soils. Kinetics studies were also done in diluted solutions of real xylem sap samples, spiked with increasing amounts of magnesium. The values obtained for the apparent rate constants were those anticipated by the proposed model. To test the validity of the methodology and mechanisms, formation rate constants, kf (M−1 s−1) of Ni(II) complexes with citrate and oxalate were evaluated that compare with the values from Eigen mechanism.</style></abstract></record><record><source-app name="Biblio" version="7.x">Drupal-Biblio</source-app><ref-type>17</ref-type><contributors><authors><author><style face="normal" font="default" size="100%">Correia dos Santos, Margarida Maria</style></author><author><style face="normal" font="default" size="100%">Alves, Sheila</style></author><author><style face="normal" font="default" size="100%">de Lurdes Simões Gonçalves, Maria</style></author><author><style face="normal" font="default" size="100%">Correia dos Santos, Margarida Maria</style></author><author><style face="normal" font="default" size="100%">Alves, Sheila</style></author><author><style face="normal" font="default" size="100%">de Lurdes Simões Gonçalves, Maria</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">Kinetics and Mechanism of Ni(II) Chelation in Model and Real Solutions of Xylem Sap of Quercus ilex</style></title><secondary-title><style face="normal" font="default" size="100%">Electroanalysis</style></secondary-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">10</style></keyword><keyword><style  face="normal" font="default" size="100%">1002</style></keyword><keyword><style  face="normal" font="default" size="100%">200703972</style></keyword><keyword><style  face="normal" font="default" size="100%">Complexation</style></keyword><keyword><style  face="normal" font="default" size="100%">Cyclic voltammetry</style></keyword><keyword><style  face="normal" font="default" size="100%">doi</style></keyword><keyword><style  face="normal" font="default" size="100%">elan</style></keyword><keyword><style  face="normal" font="default" size="100%">Kinetics</style></keyword><keyword><style  face="normal" font="default" size="100%">Nickel</style></keyword><keyword><style  face="normal" font="default" size="100%">Quercus ilex</style></keyword><keyword><style  face="normal" font="default" size="100%">Xylem sap</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">2007</style></year><pub-dates><date><style  face="normal" font="default" size="100%">2007///</style></date></pub-dates></dates><urls><web-urls><url><style face="normal" font="default" size="100%">http://dx.doi.org/10.1002/elan.200703972http://doi.wiley.com/10.1002/elan.200703972</style></url></web-urls></urls><volume><style face="normal" font="default" size="100%">19</style></volume><pages><style face="normal" font="default" size="100%">2351 - 2361</style></pages><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">The kinetics of formation and dissociation of Ni(II) complexes with oxalic and citric acids was studied by cyclic voltammetry in model solutions of xylem sap of Q. ilex (the dominant tree growing on serpentine soils of Northeast Portugal) using representative concentrations, pH and ionic strength. The role of magnesium on complex formation was analyzed from solutions where Mg is present at concentration levels found in the xylem sap of Q. ilex growing on both nonserpentine and serpentine soils. Kinetics studies were also done in diluted solutions of real xylem sap samples, spiked with increasing amounts of magnesium. The values obtained for the apparent rate constants were those anticipated by the proposed model. To test the validity of the methodology and mechanisms, formation rate constants, kf (M−1 s−1) of Ni(II) complexes with citrate and oxalate were evaluated that compare with the values from Eigen mechanism.</style></abstract><issue><style face="normal" font="default" size="100%">22</style></issue><notes><style face="normal" font="default" size="100%">The following values have no corresponding Zotero field:&lt;br/&gt;publisher: WILEY-VCH Verlag</style></notes></record><record><source-app name="Biblio" version="7.x">Drupal-Biblio</source-app><ref-type>17</ref-type><contributors><authors><author><style face="normal" font="default" size="100%">dos Santos, Margarida Maria Correia</style></author><author><style face="normal" font="default" size="100%">Alves, Sheila</style></author><author><style face="normal" font="default" size="100%">de Lurdes SimõesGonçalves, Maria</style></author><author><style face="normal" font="default" size="100%">Nabais, Cristina</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">Dynamic Modelling of Nickel Complexation in Xylem Sap of Quercus ilex: A Voltammetric Study</style></title><secondary-title><style face="normal" font="default" size="100%">Electroanalysis</style></secondary-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">Inert complexes</style></keyword><keyword><style  face="normal" font="default" size="100%">Mixed complexes</style></keyword><keyword><style  face="normal" font="default" size="100%">Nickel</style></keyword><keyword><style  face="normal" font="default" size="100%">Quercus ilex</style></keyword><keyword><style  face="normal" font="default" size="100%">Semidynamic complexes</style></keyword><keyword><style  face="normal" font="default" size="100%">Voltammetry</style></keyword><keyword><style  face="normal" font="default" size="100%">Xylem sap</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">2006</style></year><pub-dates><date><style  face="normal" font="default" size="100%">2006///</style></date></pub-dates></dates><urls><web-urls><url><style face="normal" font="default" size="100%">http://dx.doi.org/10.1002/elan.200503446</style></url></web-urls></urls><volume><style face="normal" font="default" size="100%">18</style></volume><pages><style face="normal" font="default" size="100%">814 - 822</style></pages><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">Holm oak (Quercus ilex) is the dominant tree growing on serpentine soils of northeast Portugal, characterized by elevated soil concentrations of Ni and Mg, combined with low Ca concentrations. Apparently Q. ilex does not suffer from excessive concentrations of Ni in the soil. In this work we report a complexation study of nickel by the relevant ligands present in xylem sap: histidine, aspartic acid, oxalic and citric acids, at 0.10 M ionic strength and pH 5.5. Single and mixed complexes were characterized. To validate the proposed complexation model, diluted solutions of Q. ilex xylem sap were titrated with nickel. All studies were done using square-wave voltammetry (SWV) at a hanging mercury drop electrode. Due to the dynamic nature of SWV, it is possible to obtain the conditional stability constants of the complexes formed but also to have knowledge on the kinetics of the interconversion of the species present.</style></abstract><issue><style face="normal" font="default" size="100%">8</style></issue><notes><style face="normal" font="default" size="100%">The following values have no corresponding Zotero field:&lt;br/&gt;publisher: WILEY-VCH Verlag</style></notes></record><record><source-app name="Biblio" version="7.x">Drupal-Biblio</source-app><ref-type>17</ref-type><contributors><authors><author><style face="normal" font="default" size="100%">dos Santos, Margarida Maria Correia</style></author><author><style face="normal" font="default" size="100%">Alves, Sheila</style></author><author><style face="normal" font="default" size="100%">de Lurdes SimõesGonçalves, Maria</style></author><author><style face="normal" font="default" size="100%">Nabais, Cristina</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">Dynamic Modelling of Nickel Complexation in Xylem Sap of Quercus ilex: A Voltammetric Study</style></title><secondary-title><style face="normal" font="default" size="100%">Electroanalysis</style></secondary-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">Inert complexes</style></keyword><keyword><style  face="normal" font="default" size="100%">Mixed complexes</style></keyword><keyword><style  face="normal" font="default" size="100%">Nickel</style></keyword><keyword><style  face="normal" font="default" size="100%">Quercus ilex</style></keyword><keyword><style  face="normal" font="default" size="100%">Semidynamic complexes</style></keyword><keyword><style  face="normal" font="default" size="100%">Voltammetry</style></keyword><keyword><style  face="normal" font="default" size="100%">Xylem sap</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">2006</style></year></dates><publisher><style face="normal" font="default" size="100%">WILEY-VCH Verlag</style></publisher><volume><style face="normal" font="default" size="100%">18</style></volume><pages><style face="normal" font="default" size="100%">814-822</style></pages><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">Holm oak (Quercus ilex) is the dominant tree growing on serpentine soils of northeast Portugal, characterized by elevated soil concentrations of Ni and Mg, combined with low Ca concentrations. Apparently Q. ilex does not suffer from excessive concentrations of Ni in the soil. In this work we report a complexation study of nickel by the relevant ligands present in xylem sap: histidine, aspartic acid, oxalic and citric acids, at 0.10 M ionic strength and pH 5.5. Single and mixed complexes were characterized. To validate the proposed complexation model, diluted solutions of Q. ilex xylem sap were titrated with nickel. All studies were done using square-wave voltammetry (SWV) at a hanging mercury drop electrode. Due to the dynamic nature of SWV, it is possible to obtain the conditional stability constants of the complexes formed but also to have knowledge on the kinetics of the interconversion of the species present.</style></abstract></record></records></xml>