2,840 research outputs found

    Le double visage des proches des victimes d'homicide : approche comparée en Droit Pénal et Victimologie

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    Thèse numérisée par la Division de la gestion de documents et des archives de l'Université de Montréal

    Reduction of Cadmium Availability to Tobacco ( Nicotiana tabacum ) Plants using Soil Amendments in Low Cadmium-contaminated Agricultural Soils: A Pot Experiment

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    Cadmium (Cd) concentration in field-grown tobacco leaves usually ranges from < 0.5 to 5mgCdkg-1 dry matter (DM). Reducing bioavailability of soil Cd by adding amendments to the soil could be suitable to mitigate Cd uptake by tobacco plants. However, little is known on the effect of inorganic amendments on agricultural soils with low Cd concentrations. Therefore, we performed a pot experiment with tobacco plants that were grown during 56days in two neutral to alkaline agricultural soils with low total Cd concentrations (soil 1=0.4, soil 2=0.7mgkg-1). Both soils were amended or not with 1 or 5% of sepiolite, zeolite, hydroxyapatite and apatite II™. Major and trace elements were measured in mid-stalk position leaves. Soil metals were measured in a DTPA soil extraction to assess the effect of the amendments on metal bioavailability. Some amendments significantly reduced Cd concentration in tobacco leaves, but the effect differed between the two soils tested. In soil 1, the use of zeolite at the 1% dose was the most efficient, reducing the average Cd concentration from 0.6 to 0.4mgkg-1. In soil 2, the 5% hydroxyapatite treatment led to the maximal reduction in Cd concentration (50%), with an average final Cd concentration in leaves of 0.7mgkg-1 (control: 1.5mgkg-1). There was a dose effect for some amendments in soil 2 (containing more Cd), suggesting a reduced efficiency of the amendment at the lowest addition rate. DTPA extractable Cd and Zn measured at the end of the pot experiment were correlated to the metal concentrations in tobacco leaves suggesting that (1) the reduction in leaf Cd concentration was due to a reduction in metal availability to tobacco and (2) DTPA may be a suitable extractant to estimate Cd availability to tobacco plants in these two soils. In addition, a batch experiment was performed with the same soils to test a larger number of amendments, including the four tested in the pot experiment. Results were compared to those of the pot experiment to assess whether a batch experiment may predict the efficiency of an amendment on a given soil. It gave results compatible with those from the pot experiment except for the sepiolite and highlighted the broad range of potential amendments available for heavy metal remediation in crop plant

    Metal-Poor Stars Observed with the Magellan Telescope I. Constraints on Progenitor Mass and Metallicity of AGB Stars Undergoing s-Process Nucleosynthesis

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    We present a comprehensive abundance analysis of two newly-discovered carbon-enhanced metal-poor (CEMP) stars. HE2138-3336 is a s-process-rich star with [Fe/H] = -2.79, and has the highest [Pb/Fe] abundance ratio measured thus far, if NLTE corrections are included ([Pb/Fe] = +3.84). HE2258-6358, with [Fe/H] = -2.67, exhibits enrichments in both s- and r-process elements. These stars were selected from a sample of candidate metal-poor stars from the Hamburg/ESO objective-prism survey, and followed up with medium-resolution (R ~ 2,000) spectroscopy with GEMINI/GMOS. We report here on derived abundances (or limits) for a total of 34 elements in each star, based on high-resolution (R ~ 30,000) spectroscopy obtained with Magellan-Clay/MIKE. Our results are compared to predictions from new theoretical AGB nucleosynthesis models of 1.3 Mo with [Fe/H] = -2.5 and -2.8, as well as to a set of AGB models of 1.0 to 6.0 Mo at [Fe/H] = -2.3. The agreement with the model predictions suggests that the neutron-capture material in HE2138-3336 originated from mass transfer from a binary companion star that previously went through the AGB phase, whereas for HE2258-6358, an additional process has to be taken into account to explain its abundance pattern. We find that a narrow range of progenitor masses (1.0 < M(Mo) < 1.3) and metallicities (-2.8 < [Fe/H] < -2.5) yield the best agreement with our observed elemental abundance patterns.Comment: Accepted for publication in Ap

    Solid-phase microextraction/gas chromatography–mass spectrometry method optimization for characterization of surface adsorption forces of nanoparticles

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    A complete characterization of the different physical chemical properties of nanoparticles (NPs) is necessary for the evaluation of their impact on health and environment. Among these properties, the surface characterization of the nanomaterial is the least developed and in many cases limited to the measurement of surface composition and Zeta potential. The biological surface adsorption index approach (BSAI) for characterization of surface adsorption properties of nanoparticles (NPs) has been recently introduced [1,2]. BSAI approach offers in principle the possibility to characterize the different interaction forces exerted between a nanomaterial surface and an organic –and by extension biological- entity. The present work develops further the BSAI approach of and optimizes a solid-phase microextraction – gas chromatography mass spectrometry (SPME/GC-MS) method, which is applied to measure the adsorption properties of different nanomaterials taking into account their specific surface area. This approach gives thus a better defined quantification of the adsorption properties on NPs. To optimize the SPME/GC-MS method, we investigated the various aspects of the process including: kinetics of adsorption of probe compounds on SPME fiber, kinetic of adsorption of probe compounds on NPs surface, and optimization of NPs concentration. The optimized conditions were then tested on 33 probe compounds and on Au NPs (15 nm) and SiO2 NPs (50 nm). The results demonstrated that this detailed optimization of the SPME/GC-MS method under various conditions is a critical factor and pre-requisite to the application of BSAI approach as a tool to characterize surface adsorption properties of NPs and therefore to any further conclusions on their potential impact on health.JRC.I.4-Nanobioscience

    Clima laboral y compromiso organizacional del personal de negocios de una microfinanciera de Piura – 2022

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    El estudio de investigación busco estudiar la correlación entre las variables clima laboral y compromiso organizacional en el área de negocios de una empresa microfinanciera de la ciudad de Piura en el 2022. El tipo de investigación fue básica, con un enfoque cuantitativo y diseño no experimental – correlacional. La muestra no probabilística estuvo conformada por el 55% de la población, siendo 67 colaboradores quienes participaron en la investigación. Se utilizo dos cuestionarios de 49 y 18 ítems respectivamente y con respuestas de escala de Likert. Comprobando mediante la prueba Rho de Spearman, una correlación positiva baja a nula de 0.103 a un nivel de significancia bilateral de 0.409, lo cual es mayor a 0.05; confirmando la inexistencia de una relación entre las variables dentro de esta organización microfinanciera

    Cyclic GMP protects human macrophages against peroxynitrite-induced apoptosis

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    <p>Abstract</p> <p>Background</p> <p>Nitric oxide (NO) can be both pro- and anti-apoptotic in various cell types, including macrophages. This apparent paradox may result from the actions of NO-related species generated in the microenvironment of the cell, for example the formation of peroxynitrite (ONOO<sup>-</sup>). In this study we have examined the ability of NO and ONOO<sup>- </sup>to evoke apoptosis in human monocyte-derived macrophages (MDMϕ), and investigated whether preconditioning by cyclic guanosine monophosphate (cGMP) is able to limit apoptosis in this cell type.</p> <p>Methods</p> <p>Characterisation of the NO-related species generated by (Z)-1- [2-(2-aminoethyl)-N-(2-ammonioethyl)amino]diazen-1-ium-1,2-diolate (DETA/NO) and 1,2,3,4-oxatriazolium, 5-amino-3-(3,4-dichlorophenyl)-, chloride (GEA-3162) was performed by electrochemistry using an isolated NO electrode and electron paramagnetic resonance (EPR) spectrometry. Mononuclear cells were isolated from peripheral blood of healthy volunteers and cultured to allow differentiation into MDMϕ. Resultant MDMϕ were treated for 24 h with DETA/NO (100 – 1000 μM) or GEA-3162 (10 – 300 μM) in the presence or absence of BAY 41–2272 (1 μM), isobutylmethylxanthine (IBMX; 1 μM), 1H- [1,2,4]oxadiazolo [4,3-a]quinoxalin-1-one (ODQ; 20 μM) or 8-bromo-cGMP (1 mM). Apoptosis in MDMϕ was assessed by flow cytometric analysis of annexin V binding in combination with propidium iodide staining.</p> <p>Results</p> <p>Electrochemistry and EPR revealed that DETA/NO liberated free NO radical, whilst GEA-3162 concomitantly released NO and O<sub>2</sub><sup>-</sup>, and is therefore a ONOO<sup>- </sup>generator. NO (DETA/NO) had no effect on cell viability, but ONOO<sup>- </sup>(GEA-3162) caused a concentration-dependent induction of apoptosis in MDMϕ. Preconditioning of MDMϕ with NO in combination with the phosphodiesterase inhibitor, 3-Isobutyl-1-methylxanthine (IBMX), or the NO-independent stimulator of soluble guanylate cyclase, BAY 41–2272, significantly attenuated ONOO<sup>-</sup>-induced apoptosis in a cGMP-dependent manner.</p> <p>Conclusion</p> <p>These results demonstrate disparities between the ability of NO and ONOO<sup>- </sup>to induce apoptosis in human MDMϕ. Furthermore, this study provides evidence for a novel cGMP-dependent pre-conditioning mechanism to limit ONOO<sup>-</sup>-induced apoptosis in human MDMϕ.</p

    Fully Integrated Biochip Platforms for Advanced Healthcare

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    Recent advances in microelectronics and biosensors are enabling developments of innovative biochips for advanced healthcare by providing fully integrated platforms for continuous monitoring of a large set of human disease biomarkers. Continuous monitoring of several human metabolites can be addressed by using fully integrated and minimally invasive devices located in the sub-cutis, typically in the peritoneal region. This extends the techniques of continuous monitoring of glucose currently being pursued with diabetic patients. However, several issues have to be considered in order to succeed in developing fully integrated and minimally invasive implantable devices. These innovative devices require a high-degree of integration, minimal invasive surgery, long-term biocompatibility, security and privacy in data transmission, high reliability, high reproducibility, high specificity, low detection limit and high sensitivity. Recent advances in the field have already proposed possible solutions for several of these issues. The aim of the present paper is to present a broad spectrum of recent results and to propose future directions of development in order to obtain fully implantable systems for the continuous monitoring of the human metabolism in advanced healthcare applications
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