Browsing by Author "Ortega, R."

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    Adsorption of glyphosate in Chilean soils and its relationship with unoccupied phosphate binding sites
    (EMPRESA BRASIL PESQ AGROPEC, 2003) Kogan, M.; Metz, A.; Ortega, R.
    The objective of this work was to investigate glyphosate adsorption by soils and its relationship with unoccupied binding sites for phosphate adsorption. Soil samples of three Chilean soils series-Valdivia (Andisol), Clarillo (Inceptisol) and Chicureo (Vertisol) - were incubated with different herbicide concentrations. Glyphosate remaining in solution was determined by adjusting a HPLC method with a UV detector. Experimental maximum adsorption capacity were 15,000, 14,300 and 4,700 mug g(-1) for Valdivia, Clarillo, and Chicureo soils, respectively. Linear, Freundlich, and Langmuir models were used to describe glyphosate adsorption. Isotherms describing glyphosate adsorption differed among soils. Maximum adjusted adsorption capacity with the Langmuir model was 231,884, 17,874 and 5,670 mug g(-1) for Valdivia, Clarillo, and Chicureo soils, respectively. Glyphosate adsorption on the Valdivia soil showed a linear behavior at the range of concentrations used and none of the adjusted models became asymptotic. The high glyphosate adsorption capacity of the Valdivia soil was probably a result of its high exchangeable Al, extractable Fe, and alophan and imogolite clay type. Adsorption was very much related to phosphate dynamics in the Valdivia soil, which showed the larger unoccupied phosphate binding sites. However relationship between unoccupied phosphate binding sites and glyphosate adsorption in the other two soils (Clarillo and Chicureo) was not clear.
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    Attention-deficit hyperactivity disorder involves differential cortical processing in a visual spatial attention paradigm
    (ELSEVIER IRELAND LTD, 2006) Lopez, V.; Lopez Calderon, J.; Ortega, R.; Kreither, J.; Carrasco, X.; Rothhammer, P.; Rothhammer, F.; Rosas, R.; Aboitiz, F.
    Objective: Inattention is undoubtedly one of the main characteristics of Attention-deficit hyperactivity disorder (ADHD). Nevertheless, a growing corpus of evidence shows that not all attentional processes are affected in this condition. This study aimed to explore the distribution of attentional resources in children with ADHD via a spatially shifted double-oddball visual task.
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    Dermatologic manifestations associated with HIV/AIDS
    (2015) Navarrete, C.; Fich, Félix; Ortega, R.; Concha M.
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    Mutualistic interactions reshuffle the effects of climate change on plants across the tree of life
    (2019) Bascompte, J.; Garcia, M.B.; Ortega, R.; Rezende Landaeta, Enrico; Pironon, S.