Metales pesados en huertas familiares de la ONG "Un techo para mi país"

19-29El objetivo del trabajo fue estudiar el contenido de metales pesados: Cd, Cr, Cu, Ni, Pb y Zn, en suelos de huertas orgánicas en dos barrios de Escobar (Buenos Aires), en el marco del proyecto de la ONG 'Un Techo para mi país'. Los principales factores limitantes de origen antrópico fueron materiales de relleno, basura y materiales de construcción. Los valores medios y máximos para todos los metales resultaron aceptables según lo establecido en la legislación argentina. Teniendo en cuenta valores guía internacionales de calidad de suelos, resultan los más preocupantes Cd y Pb, considerando los riesgos para la salud humana. El análisis multivariado separó a la población en dos grupos, en uno de los cuales se destacan la situación 1 con valores más elevados de Cr, Ni y Cd, y la situación 10 con altos contenidos de Pb, Zn y Cu

Observing change in pelagic animals as sampling methods shift: the case of Antarctic krill

Understanding and managing the response of marine ecosystems to human pressures including climate change requires reliable large-scale and multi-decadal information on the state of key populations. These populations include the pelagic animals that support ecosystem services including carbon export and fisheries. The use of research vessels to collect information using scientific nets and acoustics is being replaced with technologies such as autonomous moorings, gliders, and meta-genetics. Paradoxically, these newer methods sample pelagic populations at ever-smaller spatial scales, and ecological change might go undetected in the time needed to build up large-scale, long time series. These global-scale issues are epitomised by Antarctic krill (Euphausia superba), which is concentrated in rapidly warming areas, exports substantial quantities of carbon and supports an expanding fishery, but opinion is divided on how resilient their stocks are to climatic change. Based on a workshop of 137 krill experts we identify the challenges of observing climate change impacts with shifting sampling methods and suggest three tractable solutions. These are to: improve overlap and calibration of new with traditional methods; improve communication to harmonise, link and scale up the capacity of new but localised sampling programs; and expand opportunities from other research platforms and data sources, including the fishing industry. Contrasting evidence for both change and stability in krill stocks illustrates how the risks of false negative and false positive diagnoses of change are related to the temporal and spatial scale of sampling. Given the uncertainty about how krill are responding to rapid warming we recommend a shift towards a fishery management approach that prioritises monitoring of stock status and can adapt to variability and change

Observing change in pelagic animals as sampling methods shift: the case of Antarctic krill

Understanding and managing the response of marine ecosystems to human pressures including climate change requires reliable large-scale and multi-decadal information on the state of key populations. These populations include the pelagic animals that support ecosystem services including carbon export and fisheries. The use of research vessels to collect information using scientific nets and acoustics is being replaced with technologies such as autonomous moorings, gliders, and meta-genetics. Paradoxically, these newer methods sample pelagic populations at ever-smaller spatial scales, and ecological change might go undetected in the time needed to build up large-scale, long time series. These global-scale issues are epitomised by Antarctic krill (Euphausia superba), which is concentrated in rapidly warming areas, exports substantial quantities of carbon and supports an expanding fishery, but opinion is divided on how resilient their stocks are to climatic change. Based on a workshop of 137 krill experts we identify the challenges of observing climate change impacts with shifting sampling methods and suggest three tractable solutions. These are to: improve overlap and calibration of new with traditional methods; improve communication to harmonise, link and scale up the capacity of new but localised sampling programs; and expand opportunities from other research platforms and data sources, including the fishing industry. Contrasting evidence for both change and stability in krill stocks illustrates how the risks of false negative and false positive diagnoses of change are related to the temporal and spatial scale of sampling. Given the uncertainty about how krill are responding to rapid warming we recommend a shift towards a fishery management approach that prioritises monitoring of stock status and can adapt to variability and change

Family horticulture as precursory activity for social developemnt: social structure and soil analysis for a sustainable production

The objective of this work is to present orchard planning in peri-urban soils of Escobar (Buenos Aires province), in the framework of the Phase 3 Orchards Project of the NGO A Roof for my Country. Feminization of agriculture is displayed after studying growers profile. Growersaresensitized by the needto consider the qualityof the soil, and the need forsoil analysisof theirsmall farmsto detectlimiting factors andthe risk of pollutants enteringthetrophicchain. Routine analysis were performed to evaluate the productive conditions, and heavy metals Cd, Cr, Cu, Ni, Pb and Zn were also analyzed, as they may be hazardous for human health. Soil analysis showed appropiate fertility conditions, but producers should take into account other limiting factors related to their precarious accomodation. Soil average and maximum contents of heavy metals resulted acceptable as stipulated by the argentine and international guidelines.Fil: Giuffre, Lidia. Universidad de Buenos Aires. Facultad de Agronomía. Departamento de Recursos Naturales y Ambiente. Cátedra de Edafología; ArgentinaFil: Ciarlo, Esteban Ariel. Universidad de Buenos Aires. Facultad de Agronomía. Departamento de Recursos Naturales y Ambiente. Cátedra de Edafología; ArgentinaFil: Marban, Liliana Graciela. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Geocronología y Geología Isotópica. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Geocronología y Geología Isotópica; Argentina. Universidad de Buenos Aires. Facultad de Agronomía. Departamento de Recursos Naturales y Ambiente. Cátedra de Edafología; ArgentinaFil: Rios, Ruth Paola. Universidad de Buenos Aires. Facultad de Agronomía. Departamento de Recursos Naturales y Ambiente. Cátedra de Edafología; ArgentinaFil: Vespasiano, Cecilia. Universidad de Buenos Aires. Facultad de Agronomía. Departamento de Recursos Naturales y Ambiente. Cátedra de Edafología; ArgentinaFil: Sammartino, Felix. No especifica;Fil: Arata, Lucas. No especifica

ChemInform Abstract: Organic Reactions in the Solid State: The Reactivity of Guest Molecules in Tri-o-thymotide Clathrates.

Tri‐o‐thymotide (TOT) clathrates are enantiomorphous and enantioselective (chiral cages). It was shown that an external molecular reactant can diffuse into the TOT host crystal lattice and reacts with the included molecule (guest) in characteristic ways, differing from those occurring in liquid solutions. Several aspects of the action of hydrogen halides (HCl, HBr) on the chemical behavior of included oxiranes were investigated for solid‐gas and solid‐liquid (aqueous) systems. Under well established experimental conditions, these reactions gave regiospecifically one target product and were asymmetric. The included substrate underwent first an acid‐catalyzed allylic isomerization that is cage‐specific and mostly quantitative. In sheer contrast, strong basic conditions were required to promote, in reduced yield, the analogous transformation in solution. The regiospecificity and enantioselectivity of several intra‐crystalline conversions allowed the accurate determination of the absolute configuration of several guest molecules. Kinetic measurements were achieved that disclosed some striking features of this new type of heterogeneous reactions. Tentative models for the cage stereoselective mechanisms are briefly discussed

Mechanical behavior of a Y-TZP ceramic for monolithic restorations: effect of grinding and low-temperature aging

This study aimed to investigate the effects of grinding with diamond burs and low-temperature aging on the mechanical behavior (biaxial flexural strength and structural reliability), surface topography, and phase transformation of a Y-TZP ceramic for monolithic dental restorations. Disc-shaped specimens (Zirlux FC, Ivoclar Vivadent) were manufactured according to ISO 6872 (2008) and divided in accordance with two factors: “grinding — 3 levels” and “LTD — 2 levels”. Grinding was performed using a contra-angle handpiece under constant water-cooling with different grit-sizes (extra-fine and coarse diamond burs). LTD was simulated in an autoclave at 134 °C, under a pressure of 2 bar, over a period of 20 h. Surface topography analysis showed an increase in roughness based on surface treatment grit-size (Coarse > Xfine > Ctrl), LTD did not influence roughness values. Both grinding and LTD promoted an increase in the amount of m-phase, although different susceptibilities to degradation were observed. According to existing literature the increase of m-phase content is a direct indicative of Y-TZP degradation. Weibull analysis showed an increase in characteristic strength after grinding (Coarse = Xfine > Ctrl), while for LTD, distinct effects were observed (Ctrl < Ctrl LTD; Xfine = Xfine LTD and Coarse = Coarse LTD). Weibull moduli were statistically similar between all tested groups. Within the limits of this current study, it was feasible to notice that both aging in autoclave for 20 h (LTD) and grinding showed not to be detrimental to the mechanical properties of Zirlux FC Y-TZP ceramic