1,046 research outputs found

    Adsorbing vs. nonadsorbing tracers for assessing pesticide transport in arable soils

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    The suitability of two different tracers to mimic the behavior of pesticides in agricultural soils and to evidence the potential for preferential flow was evaluated in outdoor lysimeter experiments. The herbicide atrazine [6‐chloro‐N‐ethyl‐N′‐(1‐methylethyl)‐1,3,5‐triazine‐2,4‐diamine] was used as a model compound. Two tracers were used: a nonadsorbing tracer (bromide) and a weakly adsorbing dye tracer (uranine). Two soils that are expected to show a different extent of macropore preferential flow were used: a well‐drained sandy‐loamy Cambisol (gravel soil) and a poorly drained loamy Cambisol (moraine soil). Conditions for preferential flow were promoted by applying heavy simulated rainfall shortly after pesticide application. In some of the experiments, preferential flow was also artificially simulated by injecting the solutes through a narrow tube below the root zone. With depth injection, preferential leaching of atrazine occurred shortly after application in both soil types, whereas with surface application, it occurred only in the moraine soil. Thereafter, atrazine transport was mainly through the porous soil matrix, although contributions of preferential flow were also observed. For all the application approaches and soil types, after 900 d, <3% of the applied amount of atrazine was recovered in the drainage water. Only uranine realistically illustrated the early atrazine breakthrough by transport through preferential flow. Uranine broke through during the first intense irrigation at the same time as atrazine. Bromide, however, appeared earlier than atrazine in some cases. The use of dye tracers as pesticide surrogates might assist in making sustainable decisions with respect to pesticide application timing relative to rainfall or soil potential for preferential flow

    The small GTPase Arf1 regulates ATP synthesis and mitochondria homeostasis by modulating fatty acid metabolism

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    Lipid mobilization through fatty acid β-oxidation is a central process essential for energy 36 production during nutrient shortage. In yeast, this catabolic process starts in the peroxisome from where β-oxidation products enter mitochondria and fuel the TCA cycle. Little is known about the physical and metabolic cooperation between these organelles. We found that expression of fatty acid transporters and of the rate-limiting enzyme involved in β-oxidation are decreased in cells expressing a hyperactive mutant of the small GTPase Arf1, leading to an accumulation of fatty acids in lipid droplets. As a consequence, mitochondria became fragmented and ATP synthesis decreased. Genetic and pharmacological depletion of fatty acids phenocopied the arf1 mutant mitochondrial phenotype. Although β-oxidation occurs mainly in mitochondria in mammals, Arf1's role in fatty acid metabolism is conserved. Together, our results indicate that Arf1 integrates metabolism into energy production by regulating fatty acid storage and utilization, and presumably organelle contact-sites

    Increasing 3D Supramolecular Order by Decreasing Molecular Order. A Comparative Study of Helical Assemblies of Dendronized Nonchlorinated and Tetrachlorinated Perylene Bisimides

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    A nonplanar, twisted, and flexible tetrachlorinated perylene bisimide (Cl4PBI) was functionalized with two AB3 minidendrons containing hydrogenated or semifluorinated dodecyl groups. The hydrogenated dendron was attached to the imide groups of Cl4PBI via m = 0, 1, and 2 methylenic units, whereas the dendron containing semifluorinated groups was attached via m = 3 or a di(ethylene oxide) linker (m = 2EO). The supramolecular structures of these compounds, determined by a combination of differential scanning calorimetry, X-ray diffraction, and solid-state NMR, were compared with those of nonchlorinated planar and rigid PBI reported previously, which demonstrated the thermodynamically controlled formation of 2D periodic arrays at high temperatures and 3D arrays at low temperatures. The molecularly less ordered Cl4PBI containing hydrogenated dendrons self-organize into exclusively 3D crystalline periodic arrays under thermodynamic control for m = 0 and 2, while the more highly molecularly ordered PBI produced less stable and ordered 3D crystals and also 2D assemblies. This induction of a higher degree of 3D order in supramolecular assemblies of the less well-ordered molecular building blocks was unanticipated. The semifluorinated dendronized Cl4PBI with m = 3 formed a 2D columnar hexagonal array under kinetic control, whereas the compound with m = 2EO formed an unusual 2D honeycomb-like hexagonal phase under thermodynamic control. These Cl4PBI compounds provide a new route to stable crystalline assemblies via thermodynamic control at lower temperatures than previously obtained with PBI, thus generating 3D order in an accessible range of temperature of interest for structural analysis and for technological applications

    What kinds of value motives guide people in their moral attitudes? The role of personal and prescriptive values at the culture level and individual level

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    Opinions about moralized issues are arguably one of the most difficult issues in interpersonal dialogues given that they can result in intolerance and prejudicial behavior toward those with divergent moral beliefs. Recent research has shown that moral attitudes vary not only depending on the individual's characteristics but also as a function of culture. Individuals from individualistic-oriented cultures exhibit more lenient judgments toward moralized issues than those from collectivistic-oriented cultures. What is unclear to date is what kinds of cultural value motives underlie these attitudesAre they driven only by intrinsic value motives (personal values) or also by extrinsic value motives (prescriptive values in the form of societal expectations about what should be valued)? The cultural press to conform is arguably stronger if moral attitudes are predicted by the latter. Participants from eight countries (N = 1,456) responded to a questionnaire containing a modified version of the Schwartz Value Survey assessing personal and prescriptive values. The results showed that personal value ratings of openness-to-change versus conservation at the culture and individual levels were predictive of individuals' moral attitudes consistent with previous findings. Prescriptive value ratings of openness-to-change versus conservation also predicted individuals' moral attitudes, but only at the aggregated culture level. This suggests that the prescriptive values concept is a truly group-level phenomenon and that attitudes toward moralized issues are guided by cultural values with normative qualities. We discuss the implications for intercultural contact situations.info:eu-repo/semantics/acceptedVersio

    Dropstones in the Mar del Plata Canyon Area (SW Atlantic): Evidence for Provenance, Transport, Distribution, and Oceanographic Implications

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    A variety of gravel- to cobble-sized rocks, recovered from the Mar del Plata (MdP) Canyon area (Western South Atlantic at 38°S) and interpreted as ice-rafted debris, represent the first evidence that large icebergs have floated in the Falkland (Malvinas) Current from the southern polar high latitudes far northward. Detailed petrographic analyses identified the Antarctic Peninsula, sub-Antarctic islands in the Scotia Sea, and Tierra del Fuego as plausible source areas. The drift process could have started as early as at the beginning of the last deglaciation, according to an age obtained from a cold-water coral fragment associated with one of the dropstones. At the end of the Last Glacial Maximum, large icebergs have been supplied to the Antarctic Circumpolar Current, captured by those ocean current branches that circumvent the Falkland (Malvinas) Islands and entered the Argentine Margin. When the iceberg fleets approached the Brazil-Falkland (Malvinas) Confluence Zone with its steep latitudinal temperature gradient, the icebergs got oceanographically trapped and melted off rapidly. The sediment load sinking down to the seafloor formed a dropstone blanket particularly where the MdP Canyon had incised into the continental slope. Here, mass-flow processes, induced by local slope instability, and along-slope sediment resorting, due to the erosional effects of strong and persistent contouritic bottom currents, favored local enrichment in dropstones in the form of a loose, coarse sediment drape inside morphological depressions. The bottom current velocity would be locally strong enough to rework this sediment, leaving coarse rafted debris as a lag deposit.Fil: Bozzano, Graziella. Ministerio de Defensa. Armada Argentina. Servicio de Hidrografía Naval; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Cerredo, Maria Elena. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Geociencias Básicas, Aplicadas y Ambientales de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Geociencias Básicas, Aplicadas y Ambientales de Buenos Aires; ArgentinaFil: Remesal, Marcela Beatriz. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Geociencias Básicas, Aplicadas y Ambientales de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Geociencias Básicas, Aplicadas y Ambientales de Buenos Aires; ArgentinaFil: Steinmann, L.. Universitat Bremen; AlemaniaFil: Hanebuth, Till J.J.. Coastal Carolina University; Estados UnidosFil: Schwenk, T.. Universitat Bremen; AlemaniaFil: Baqués, Michele. Ministerio de Defensa. Armada Argentina. Servicio de Hidrografía Naval; Argentina. Ministerio de Defensa. Armada Argentina. Dirección Gral. de Investigación y Desarrollo de la Ara. Dirección de Investigación de la Armada; ArgentinaFil: Hebbeln, Dierk. Universitat Bremen; AlemaniaFil: Spoltore, Daniela Veronica. Ministerio de Defensa. Armada Argentina. Servicio de Hidrografía Naval; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Oficina de Coordinación Administrativa Ciudad Universitaria. Instituto de Geociencias Básicas, Aplicadas y Ambientales de Buenos Aires. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Instituto de Geociencias Básicas, Aplicadas y Ambientales de Buenos Aires; ArgentinaFil: Silvestri, Ornella. Ministerio de Defensa. Armada Argentina. Servicio de Hidrografía Naval; Argentina. Universidad de Buenos Aires; ArgentinaFil: Acevedo, Rogelio Daniel. Universidad Nacional de Tierra del Fuego, Antártida e Islas del Atlántico Sur. Instituto de Ciencias Polares, Ambientales y Recursos Naturales; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Austral de Investigaciones Científicas; ArgentinaFil: Spiess, V.. Universitat Bremen; AlemaniaFil: Violante, Roberto Antonio. Ministerio de Defensa. Armada Argentina. Servicio de Hidrografía Naval; ArgentinaFil: Kasten, Sabine. Universitat Bremen; Alemania. Alfred Wegener Institute Helmholtz Centre for Polar and Marine Research; Alemani
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