601 research outputs found

    Structure of reverse microemulsion-templated metal hexacyanoferrate nanoparticles

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    The droplet phase of a reverse microemulsion formed by the surfactant cetyltrimethylammonium ferrocyanide was used as a matrix to synthesize nanoparticles of nickel hexacyanoferrate by adding just a solution of NiCl2 to the microemulsion media. Dynamic light scattering and small-angle neutron scattering measurements show that the reverse microemulsion droplets employed have a globular structure, with sizes that depend on water content. Transmission electron microscopy and electron diffraction are used to obtain information about the structure of the synthesized nanoparticles. The results show that the size and shape of the coordination compound nanoparticles correspond with the size and shape of the droplets, suggesting that the presented system constitutes an alternative method of the synthesis of metal hexacyanoferrate nanoparticles

    Micro- and nanoplastics current status: legislation, gaps, limitations and socio-economic prospects for future

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    The pollution caused by micro- (MP) and nanoplastics (NP) in the planet’s ecosystems has gained significant interest in recent years due to their environmental impact and effects on the health of living organisms. Given this, it is necessary to conduct a comprehensive analysis of the actions required to mitigate their impacts. This paper analyzes existing legislation across different countries and regions, including Europe, North America, China, Russia, India, Brazil, Mexico, and the global initiatives undertaken by the United Nations. Furthermore, it highlights the need for additional measures to mitigate the impact of MP/NP in future years, such as the development of technologies for the separation or degradation of these particles in water intended for human consumption and in wastewater treatment plant effluents, studying plastic particulate material in the air considering meteorological parameters, MP/NP detection protocols in human fluid samples, creating truly biodegradable polymers for use as bioplastics, and establishing institutions responsible for the management of plastic waste. The study also shows the current state of abundance (characterization and quantification) of MP/NP in different environmental matrices based on reports from recent years, and identifies key research opportunities and actions required to evaluate the risks and toxicity associated with MP/NP. Socio-economic aspects are considered, including the impact of MP/NP on different regions, by associating economic and human wellness parameters to plastic waste generation by using available data from 148 countries. As result of this analysis, both the most populated and developed countries contribute to MP/NP generation, however, they have different capacities to address this problem due to social circumstances. The solution to this problem requires efforts from authorities, industry, the scientific community, and the active participation of the population, then, resolving social, political, and economic issues between countries and regions of the world is necessary

    Efecto repelente y tiempo de protección de aceites esenciales frente al estadio adulto de Aedes aegypti

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    The aim of this was to evaluate the repellent effect and protection time of essential oils against the adult Aedes aegypti mosquito. A completely randomized design was used with a factorial arrangement that included 10 essential oils (Minthostachys mollis, Schinus molle, Ruta graveolens, Piper aduncun, Myrica pubescens, Lippia alba, Mentha piperita, Lantana glutinosa, Cymbopogon citratus, Eucalyptus globulus and the DEET control. 10%) and four concentrations of the oils (125, 250, 500 and 1000 mg/ml). Each experimental group consisted of 50 adult female A. aegypti mosquitoes raised in the laboratory and the repellent effect and protection time were evaluated using a sedated animal bait (Rattus rattus) with applications of 0.1 ml of the oils on the legs, tail and face. The rats and mosquitoes were found in two communicating cages of 25x25x40 cm. The oils with the greatest repellent effect and protection time, respectively, were C. citratus (97.4%; 165 minutes), E. globulus (95.8%; 165 minutes), L. glutinosa (93.8%; 180 minutes) and M. piperite (93.5%; 180 minutes) in its highest concentration (1000 mg/l); with differences between oils and between concentrations (p<0.001). Likewise, DEET 10% obtained a repellency of 95.3% and a protection time of 173 minutes. It is concluded that the essential oils of C. citratus, E. globulus, L. glutinosa and M. piperita can be considered as having natural repellent potential for A. aegypti.El estudio tuvo como objetivo evaluar el efecto repelente y tiempo de protección de aceites esenciales frente al mosquito adulto de Aedes aegypti. Se trabajó con un diseño completamente al azar con arreglo factorial que incluyó 10 aceites esenciales (Minthostachys mollis, Schinus molle, Ruta graveolens, Piper aduncun, Myrica pubescens, Lippia alba, Mentha piperita, Lantana glutinosa, Cymbopogon citratus, Eucalyptus globulus y el control DEET 10%) y cuatro concentraciones de los aceites (125, 250, 500 y 1000 mg/ml). Cada grupo experimental se constituyó por 50 mosquitos hembra adultos de A. aegypti criados en laboratorio y el efecto repelente y tiempo de protección se evaluaron usando un cebo animal sedado (Rattus rattus) con aplicaciones de 0.1 ml de los aceites en patas, cola y cara. Las ratas y los mosquitos se encontraron en dos jaulas comunicadas de 25x25x40 cm. Los aceites con mayor efecto repelente y tiempo de protección, respectivamente, fueron: C. citratus (97.4%; 165 minutos), E. globulus (95.8%; 165 minutos), L. glutinosa (93.8%; 180 minutos) y M. piperita (93.5%; 180 minutos) en su concentración mayor concentración (1000 mg/l); con diferencias entre aceites y entre concentraciones (p<0.001). Asimismo, el DEET 10% obtuvo una repelencia de 95.3 % y tiempo de protección de 173 minutos. Se concluye que los aceites esenciales de C. citratus, E. globulus, L. glutinosa y M. piperita pueden considerarse con potencial repelente natural para A. aegypti

    Matemáticas en contexto

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    El libro compila estrategias didácticas derivadas del programa de formación complementario escritas por instructores técnicos de diferentes regionales del país, describe la forma en que se incorpora el conocimiento matemático en campos específicos de diferentes áreas de formación laboral basado en las teorías didácticas y reflexiones pedagógicas de instructores.The book compiles the didactic strategies derived from the complementary training program by the technical instructors of the regional media of the country, describes the way in which mathematical knowledge is incorporated in the fields of different areas of work training based on theories didactic and pedagogical reflections of instructors.Consideraciones frente al aprendizaje de las matemáticas -- Perspectiva constructivista -- Teoría de las situaciones didácticas -- Modelación matemática -- Mediación tecnológica -- Pensamiento numérico variacional -- Pensamiento numérico -- Pensamiento variacional -- Diseño de modelo matemático con aplicación de costos de producción -- Modelo matemático del consumo de gas en un artefacto afectado por su presión de trabajo -- Planeación de la producción agrícola: Caso plan óptimo de siembra que permita alcanzar la máxima rentabilidad del cultivo -- Estudio del Álgebra de Boole -- Diseño de un modelo de inventarios para una pequeña empresa de calzado de dotación -- Estudio de la Ley de Ohm mediante herramienta interactiva -- Pensamiento métrico-geométrico -- Pensamiento geométrico -- Pensamiento métrico -- Caso de optimización de recursos en el sector industrial de la confección -- Optimización de espacios para huertas urbanas -- Optimización de los costos del espacio de almacenamiento en microempresas y pequeñas empresas de acuerdo con las normas de seguridad vigentes -- Unidad de medida métrica para confección de ropa exterior femenina -- Optimización de recursos aplicando el proceso administrativo -- Pensamiento aleatorio -- Estadística Básica para Articulación con la Media -- Evaluación del impacto de la accidentalidad en la implementación del Sistema de Gestión de Seguridad y Salud en el Trabajo (sg-sst) por medio de indicadores -- Identificar los aspectos de la declaración de renta para una persona natural no obligada a llevar contabilidad -- Fortalecimiento de la estadística: caso de las unidades productivas del Centro de Biotecnología Agropecuaria -- Estadística dinámica -- Resultados preliminaresna[270 páginas

    RICORS2040 : The need for collaborative research in chronic kidney disease

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    Chronic kidney disease (CKD) is a silent and poorly known killer. The current concept of CKD is relatively young and uptake by the public, physicians and health authorities is not widespread. Physicians still confuse CKD with chronic kidney insufficiency or failure. For the wider public and health authorities, CKD evokes kidney replacement therapy (KRT). In Spain, the prevalence of KRT is 0.13%. Thus health authorities may consider CKD a non-issue: very few persons eventually need KRT and, for those in whom kidneys fail, the problem is 'solved' by dialysis or kidney transplantation. However, KRT is the tip of the iceberg in the burden of CKD. The main burden of CKD is accelerated ageing and premature death. The cut-off points for kidney function and kidney damage indexes that define CKD also mark an increased risk for all-cause premature death. CKD is the most prevalent risk factor for lethal coronavirus disease 2019 (COVID-19) and the factor that most increases the risk of death in COVID-19, after old age. Men and women undergoing KRT still have an annual mortality that is 10- to 100-fold higher than similar-age peers, and life expectancy is shortened by ~40 years for young persons on dialysis and by 15 years for young persons with a functioning kidney graft. CKD is expected to become the fifth greatest global cause of death by 2040 and the second greatest cause of death in Spain before the end of the century, a time when one in four Spaniards will have CKD. However, by 2022, CKD will become the only top-15 global predicted cause of death that is not supported by a dedicated well-funded Centres for Biomedical Research (CIBER) network structure in Spain. Realizing the underestimation of the CKD burden of disease by health authorities, the Decade of the Kidney initiative for 2020-2030 was launched by the American Association of Kidney Patients and the European Kidney Health Alliance. Leading Spanish kidney researchers grouped in the kidney collaborative research network Red de Investigación Renal have now applied for the Redes de Investigación Cooperativa Orientadas a Resultados en Salud (RICORS) call for collaborative research in Spain with the support of the Spanish Society of Nephrology, Federación Nacional de Asociaciones para la Lucha Contra las Enfermedades del Riñón and ONT: RICORS2040 aims to prevent the dire predictions for the global 2040 burden of CKD from becoming true

    Combined searches for the production of supersymmetric top quark partners in proton-proton collisions at root s=13 TeV

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    A combination of searches for top squark pair production using proton-proton collision data at a center-of-mass energy of 13 TeV at the CERN LHC, corresponding to an integrated luminosity of 137 fb(-1) collected by the CMS experiment, is presented. Signatures with at least 2 jets and large missing transverse momentum are categorized into events with 0, 1, or 2 leptons. New results for regions of parameter space where the kinematical properties of top squark pair production and top quark pair production are very similar are presented. Depending on themodel, the combined result excludes a top squarkmass up to 1325 GeV for amassless neutralino, and a neutralinomass up to 700 GeV for a top squarkmass of 1150 GeV. Top squarks with masses from 145 to 295 GeV, for neutralino masses from 0 to 100 GeV, with a mass difference between the top squark and the neutralino in a window of 30 GeV around the mass of the top quark, are excluded for the first time with CMS data. The results of theses searches are also interpreted in an alternative signal model of dark matter production via a spin-0 mediator in association with a top quark pair. Upper limits are set on the cross section for mediator particle masses of up to 420 GeV

    Search for new particles in events with energetic jets and large missing transverse momentum in proton-proton collisions at root s=13 TeV

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    A search is presented for new particles produced at the LHC in proton-proton collisions at root s = 13 TeV, using events with energetic jets and large missing transverse momentum. The analysis is based on a data sample corresponding to an integrated luminosity of 101 fb(-1), collected in 2017-2018 with the CMS detector. Machine learning techniques are used to define separate categories for events with narrow jets from initial-state radiation and events with large-radius jets consistent with a hadronic decay of a W or Z boson. A statistical combination is made with an earlier search based on a data sample of 36 fb(-1), collected in 2016. No significant excess of events is observed with respect to the standard model background expectation determined from control samples in data. The results are interpreted in terms of limits on the branching fraction of an invisible decay of the Higgs boson, as well as constraints on simplified models of dark matter, on first-generation scalar leptoquarks decaying to quarks and neutrinos, and on models with large extra dimensions. Several of the new limits, specifically for spin-1 dark matter mediators, pseudoscalar mediators, colored mediators, and leptoquarks, are the most restrictive to date.Peer reviewe

    Probing effective field theory operators in the associated production of top quarks with a Z boson in multilepton final states at root s=13 TeV

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    Measurements of the Electroweak Diboson Production Cross Sections in Proton-Proton Collisions at root s=5.02 TeV Using Leptonic Decays

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    The first measurements of diboson production cross sections in proton-proton interactions at a center-of-mass energy of 5.02 TeV are reported. They are based on data collected with the CMS detector at the LHC, corresponding to an integrated luminosity of 302 pb(-1). Events with two, three, or four charged light leptons (electrons or muons) in the final state are analyzed. The WW, WZ, and ZZ total cross sections are measured as sigma(WW) = 37:0(-5.2)(+5.5) (stat)(-2.6)(+2.7) (syst) pb, sigma(WZ) = 6.4(-2.1)(+2.5) (stat)(-0.3)(+0.5)(syst) pb, and sigma(ZZ) = 5.3(-2.1)(+2.5)(stat)(-0.4)(+0.5) (syst) pb. All measurements are in good agreement with theoretical calculations at combined next-to-next-to-leading order quantum chromodynamics and next-to-leading order electroweak accuracy

    Search for lepton-flavor violating decays of the Higgs boson in the mu tau and e tau final states in proton-proton collisions at root s=13 TeV

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    A search is presented for lepton-flavor violating decays of the Higgs boson to mu t and et. The dataset corresponds to an integrated luminosity of 137 fb(-1) collected at the LHC in proton-proton collisions at a center-of-mass energy of 13 TeV. No significant excess has been found, and the results are interpreted in terms of upper limits on lepton-flavor violating branching fractions of the Higgs boson. The observed (expected) upper limits on the branching fractions are, respectively, B(H -> mu t) e tau) < 0.22(0.16)% at 95% confidence level.Peer reviewe
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