Effect of phosphorus on the attenuation of lead and chromium

This study analyses the adsorption of Pb(II) and Cr(III) in soils. These metals are commonly found together in nature in urban wastes or industrial spillages, and the theoretical approach of the work was to evaluate the response of the soil to continuous Cr and Pb spillages to soil in terms of several physicochemical parameters. The influence of an anthropogenic input of phosphorus was evaluated. Continuous flow experiments were run in duplicates in acrylic columns (25 cm × 3.2 cm). The influent Cr(III) and Pb(II) solutions of 10 mg l−1 and 25 mg l−1 at pH 5 were pumped upward through the bottom of the columns to ensure saturation flow conditions. Also, successive experiments were run with the above concentrations of Cr(III) and Pb(II) and NaH2PO4, keeping metal to phosphorus ratio of 1:0, 1:0.1 and 1:1. Modelling parameters included Freundlich and Langmuir equations, together with the Two-site adsorption model using CXTFIT code. Results obtained allowed concluding that Pb(II) adsorption presents a certain degree of irreversibility and the continued spillages over soil increment the fraction which is not easily desorbed. Cr(III) desorption was almost complete, evidencing its high mobility in nature. The presence of an anthropogenic input of phosphorus leads to a marked increase of both Pb(II) and Cr(III) adsorption in soils. Z-potential measurements allow to discard the electrostatic attraction of Cr(III) and Pb(II) with the surface charged soil as the dominant process of metal sorption. Instead, CheaqsPro simulation allows to identify PbH2PO4 +, PbHPO4 (aq) and CrHPO4 + as the dominant species which regulate Cr(III) and Pb(II) transport in soils.Fundação para a Ciência e a Tecnologi

The influence of the segmentation process on 3D measurements from cone beam computed tomography-derived surface models

<p>To compare the accuracy of linear and angular measurements between cephalometric and anatomic landmarks on surface models derived from 3D cone beam computed tomography (CBCT) with two different segmentation protocols was the aim of this study. CBCT scans were made of cadaver heads and 3D surface models were created of the mandible using two different segmentation protocols. A high-resolution laser surface scanner was used to make a 3D model of the macerated mandibles. Twenty linear measurements at 15 anatomic and cephalometric landmarks between the laser surface scan and the 3D models generated from the two segmentation protocols (commercial segmentation (CS) and doctor's segmentation (DS) groups) were measured. The interobserver agreement for all the measurements of the all three techniques was excellent (intraclass correlation coefficient 0.97-1.00). The results are for both groups very accurate, but only for the measurements on the condyle and lingual part of the mandible, the measurements in the CS group is slightly more accurate than the DS group. 3D surface models produced by CBCT are very accurate but slightly inferior to reality when threshold-based methods are used. Differences in the segmentation process resulted in significant clinical differences between the measurements. Care has to be taken when drawing conclusions from measurements and comparisons made from different segmentations, especially at the condylar region and the lingual side of the mandible.</p>

Tropical Ungulates of Argentina

Argentina has an extensive and diverse terrain classified into 11 ecoregions. Seven of these ecoregions, occupying the north and north-central parts of the country, house the 11 tropical ungulate species found here. The ecoregions are lowland and subtropical, some beginning in the tropics, some extending to temperate climates. The principal topographical characteristics, hydrology, climate, vegetation and fauna are described for these seven ecoregions. Each of the 11 species is then treated in detail with respect to its ecology and conservation. Emphasis is placed on distribution, habitat and density, feeding ecology, threats and conservation in Argentina, based on the most recent studies. Data on reproductive biology and behaviour are included where information is relatively recent and unlikely to be covered elsewhere. The species include the following: the Brazilian tapir (Tapirus terrestris), found in northern subtropical ecoregions, three species of peccary (Tayassu pecari, Pecari tajacu and Parachoerus wagneri) from northern subtropical and drier regions, of which the Chacoan peccary (P. wagneri) is endemic while the other two species have more extensive distributions. The guanaco (Lama guanicoe) occurs only in relict populations in the ecoregions considered. The taruca (Hippocamelus antisensis) occupies the eastern boundary between the Yungas and drier, high altitude ecoregions. Three species of brocket deer (Mazama americana, M. gouazoubira and M. nana) occupy the northern tropical, subtropical and Chacoan areas. The marsh deer (Blastocerus dichotomus), the largest South American deer, has small populations occupying wetlands from the northern border to the Parana delta, while the pampas deer (Ozotocerus bezoaticus) is found in four isolated populations from Ibera to Buenos Aires province. Argentina represents the southern limit to the distribution of all these species and thus threats are often magnified. Ongoing conservation activities include the maintenance of protected areas, promotion (difusion, education, sensitization), investigation and the reintroduction of some species of formerly extinct ungulates into the Ibera wetlands area.Fil: Black Decima, Patricia. Universidad Nacional de Tucumán; ArgentinaFil: Camino, Micaela. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Centro de Ecología Aplicada del Litoral. Universidad Nacional del Nordeste. Centro de Ecología Aplicada del Litoral; ArgentinaFil: Cirignoli, Sebastian. Centro de Investigaciones del Bosque Atlántico; ArgentinaFil: de Bustos, Soledad. Fundación Biodiversidad; ArgentinaFil: Matteucci, Silvia Diana. Universidad de Buenos Aires. Facultad de Arquitectura y Urbanismo. Grupo de Ecología del Paisaje y Medio Ambiente; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Perez Carusi, Lorena Cynthia. Administración de Parques Nacionales; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Varela, Diego Martin. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Nordeste. Instituto de Biología Subtropical. Universidad Nacional de Misiones. Instituto de Biología Subtropical; Argentina. Centro de Investigaciones del Bosque Atlántico; Argentin