<?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%">Campelo, Filipe</style></author><author><style face="normal" font="default" size="100%">Nabais, Cristina</style></author><author><style face="normal" font="default" size="100%">Gutiérrez, Emilia</style></author><author><style face="normal" font="default" size="100%">Freitas, Helena</style></author><author><style face="normal" font="default" size="100%">García-González, Ignacio</style></author></authors></contributors><titles><title><style face="normal" font="default" size="100%">Vessel features of Quercus ilex L. growing under Mediterranean climate have a better climatic signal than tree-ring width</style></title><secondary-title><style face="normal" font="default" size="100%">Trees</style></secondary-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">Dendrochronology</style></keyword><keyword><style  face="normal" font="default" size="100%">Holm oak</style></keyword><keyword><style  face="normal" font="default" size="100%">Mediterranean climate</style></keyword><keyword><style  face="normal" font="default" size="100%">Tree ring</style></keyword><keyword><style  face="normal" font="default" size="100%">Vessel features</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">2010</style></year><pub-dates><date><style  face="normal" font="default" size="100%">2010///</style></date></pub-dates></dates><urls><web-urls><url><style face="normal" font="default" size="100%">http://www.springerlink.com/index/10.1007/s00468-010-0414-0</style></url></web-urls></urls><volume><style face="normal" font="default" size="100%">24</style></volume><pages><style face="normal" font="default" size="100%">463 - 470</style></pages><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">We investigated whether vessel time series of Holm oak (Quercus ilex L.), a diffuse to semi-ring-porous species, can record a climatic signal which differs from the signal encoded in tree-ring width (TRW). The study was conducted in ten Q. ilex trees from a coppice stand in northeast Spain. Chronologies of TRW, mean vessel area (MVA) and maximum vessel area (MAX) were developed and correlated with climate data, for the period 1985–2004 (20 years). Our results indicate that vessel features contain environmental information that is different from that stored in TRW. MAX chronologies correlate better to early spring precipitation (April–May) than TRW chronologies, and so does MVA of the largest 20–25 vessels from the ﬁrst third of the ring with late spring precipitation (May–June). Also, the combination of MVA and TRW is a better predictor of summer precipitation. This explorative study clearly shows that vessel features can complement the climatic signal of TRW increasing the resolution of the climate reconstructions for the Mediterranean region.</style></abstract><issue><style face="normal" font="default" size="100%">3</style></issue></record><record><source-app name="Biblio" version="7.x">Drupal-Biblio</source-app><ref-type>17</ref-type><contributors></contributors><titles><title><style face="normal" font="default" size="100%">Nickel sorption capacity of ground xylem of Quercus ilex trees and effects of selected ligands present in the xylem sap.</style></title><secondary-title><style face="normal" font="default" size="100%">Journal of plant physiology</style></secondary-title></titles><dates><year><style  face="normal" font="default" size="100%">2009</style></year></dates><volume><style face="normal" font="default" size="100%">166</style></volume><pages><style face="normal" font="default" size="100%">270-277</style></pages><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">In this work the influence of four different ligands present in the xylem sap of Quercus ilex (histidine, citric, oxalic and aspartic acids) on Ni(II) adsorption by xylem was investigated. Grinded xylem was trapped in acrylic columns and solutions of Ni(II), in the absence and presence of the four ligands prepared in KNO(3) 0.1molL(-1) at pH 5.5, were percolated through the column. Aliquots of solutions were recovered in the column end for Ni determination by graphite furnace atomic absorption spectrometry (GFAAS). The experimental data to describe Ni sorption by xylem in both the presence and absence of ligands was better explained by the Freundlich isotherm model. The decreasing affinity order of ligands for Ni was: oxalic acid&gt;citric acid&gt;histidine&gt;aspartic acid. On the other hand, the Ni(II) adsorption by xylem increased following the inverse sequence of ligands. Potentiometric titrations of acidic groups were carried out to elucidate the sorption site groups available in Q. ilex xylem. The potentiometric titration has shown three sorption sites: pK(a) 2.6 (57.7% of the sorption sites), related to monobasic aliphatic carboxylic acids or nitrogen aromatic bases, pK(a) 8.1 (9.6%) and pK(a) 9.9 (32.7%), related to phenolic groups.</style></abstract><accession-num><style face="normal" font="default" size="100%">18707798</style></accession-num></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%">Araújo, Geórgia C. L.</style></author><author><style face="normal" font="default" size="100%">Lemos, Sherlan G.</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%">Nickel sorption capacity of ground xylem of Quercus ilex trees and effects of selected ligands present in the xylem sap.</style></title><secondary-title><style face="normal" font="default" size="100%">Journal of plant physiology</style></secondary-title></titles><keywords><keyword><style  face="normal" font="default" size="100%">Adsorption isotherms</style></keyword><keyword><style  face="normal" font="default" size="100%">Nickel</style></keyword><keyword><style  face="normal" font="default" size="100%">Organic ligands</style></keyword><keyword><style  face="normal" font="default" size="100%">Xylem</style></keyword></keywords><dates><year><style  face="normal" font="default" size="100%">2009</style></year><pub-dates><date><style  face="normal" font="default" size="100%">2009///</style></date></pub-dates></dates><urls><web-urls><url><style face="normal" font="default" size="100%">http://www.ncbi.nlm.nih.gov/pubmed/18707798</style></url></web-urls></urls><volume><style face="normal" font="default" size="100%">166</style></volume><pages><style face="normal" font="default" size="100%">270 - 277</style></pages><language><style face="normal" font="default" size="100%">eng</style></language><abstract><style face="normal" font="default" size="100%">In this work the influence of four different ligands present in the xylem sap of Quercus ilex (histidine, citric, oxalic and aspartic acids) on Ni(II) adsorption by xylem was investigated. Grinded xylem was trapped in acrylic columns and solutions of Ni(II), in the absence and presence of the four ligands prepared in KNO(3) 0.1molL(-1) at pH 5.5, were percolated through the column. Aliquots of solutions were recovered in the column end for Ni determination by graphite furnace atomic absorption spectrometry (GFAAS). The experimental data to describe Ni sorption by xylem in both the presence and absence of ligands was better explained by the Freundlich isotherm model. The decreasing affinity order of ligands for Ni was: oxalic acid&gt;citric acid&gt;histidine&gt;aspartic acid. On the other hand, the Ni(II) adsorption by xylem increased following the inverse sequence of ligands. Potentiometric titrations of acidic groups were carried out to elucidate the sorption site groups available in Q. ilex xylem. The potentiometric titration has shown three sorption sites: pK(a) 2.6 (57.7% of the sorption sites), related to monobasic aliphatic carboxylic acids or nitrogen aromatic bases, pK(a) 8.1 (9.6%) and pK(a) 9.9 (32.7%), related to phenolic groups.</style></abstract><issue><style face="normal" font="default" size="100%">3</style></issue><notes><style face="normal" font="default" size="100%">The following values have no corresponding Zotero field:&lt;br/&gt;accession-num: 18707798</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></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><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>