2,618 research outputs found

    Review on sol-gel synthesis of perovskite and oxide nanomaterials

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    Altres ajuts: this work has been partially financed by the CERCA Programme/Generalitat de Catalunya.Sol-Gel is a low cost, well-established and flexible synthetic route to produce a wide range of micro- and nanostructures. Small variations in pH, temperature, precursors, time, pressure, atmosphere, among others, can lead to a wide family of compounds that share the same molecular structures. In this work, we present a general review of the synthesis of LaMnO, SrTiO, BaTiO perovskites and zinc vanadium oxides nanostructures based on Sol-Gel method. We discuss how small changes in the parameters of the synthesis can modify the morphology, shape, size, homogeneity, aggregation, among others, of the products. We also discuss the different precursors, solvents, working temperature, reaction times used throughout the synthesis. In the last section, we present novel uses of Sol-Gel with organic materials with emphasis on carbon-based compounds. All with a perspective to improve the method for future applications in different technological fields

    Thermal rectification and thermal logic gates in graded alloy semiconductors

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    Classical thermal rectification arises from the contact between two dissimilar bulk materials, each with a thermal conductivity (k) with a different temperature dependence. Here, we study thermal rectification in a SiGe alloy with a spatial dependence on the atomic composition. Rectification factors (R = k/k) of up to 3.41 were found. We also demonstrate the suitability of such an alloy for logic gates using a thermal AND gate as an example by controlling the thermal conductivity profile via the alloy composition. This system is readily extendable to other alloys, since it only depends on the effective thermal conductivity. These thermal devices are inherently advantageous alternatives to their electric counterparts, as they may be able to take advantage of otherwise undesired waste heat in the surroundings. Furthermore, the demonstration of logic operations is a step towards thermal computation

    Detection of a new community genotype methicillin-resistant staphylococcus aureus clone that is unrelated to the USA300 clone and that causes pediatric infections in colombia

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    The dissemination of a clone of community genotype methicillin-resistant Staphylococcus aureus (CG-MRSA) that is related to USA300 has been reported in Latin America. We recently detected isolates of a new clone of CG-MRSA (spa type t1635 and ACME-negative) that was genetically unrelated to the USA300 clone and that causes infections in children in Colombia. This finding indicates the appearance of a new clone of CG-MRSA in our region. Copyright © 2013, American Society for Microbiology

    The Impact of Postnatal Systemic Steroids on the Growth of Preterm Infants: A Multicenter Cohort Study

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    Postnatal steroids, often used to prevent and treat bronchopulmonary dysplasia, may influence the growth of preterm infants, although data are scarce in the literature. This is a multicenter cohort study including surviving preterm infants <32 weeks at birth (n = 17,621) from the Spanish Neonatal Network SEN1500 database, without major congenital malformations. Linear regression models were adjusted for postnatal steroids, respiratory severity course (invasive mechanical ventilation at 28 days), progression to moderate-severe bronchopulmonary dysplasia (O2 at 36 weeks), length of stay, sex, gestational age and z-scores at birth. A subgroup analysis depending on the timing of administration, ventilation status at 28 days and moderate-severe BPD diagnosis was also performed. Overall, systemic postnatal steroids were not independently associated with poorer weight gain (0.1; 95% CI: -0.05 to 0.2 g/kg/day), linear growth (0; 95% CI: -0.03 to 0.01 cm/week) or head circumference growth (-0.01; 95% CI: -0.02 to 0 cm/week). Patients who received steroids after 28 days or who were not O2 dependent at 36 weeks after having received steroids gained more weight (0.22; 95% CI: 0.04 to 0.4 and 0.2; 95% CI: 0.004 to 0.5 g/kg/day, respectively). Globally, systemic postnatal steroids had no significant adjusted effect on postnatal growth

    Extragalactic magnetism with SOFIA (SALSA Legacy Program). VI. The magnetic fields in the multi-phase interstellar medium of the Antennae galaxies

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    Mergers are thought to be a fundamental channel for galaxy growth, perturbing the gas dynamics and the magnetic fields (B-fields) in the interstellar medium (ISM). However, the mechanisms that amplify and dissipate B-fields during a merger remain unclear. We characterize the morphology of the ordered B-fields in the multi-phase ISM of the closest merger of two spiral galaxies, the Antennae galaxies. We compare the inferred B-fields using 154 μ154~\mum thermal dust and 1111 cm radio synchrotron emission polarimetric observations. We find that the 154 μ154~\mum B-fields are more ordered across the Antennae galaxies than the 1111 cm B-fields. The turbulent-to-ordered 154 μ154~\mum B-field increases at the galaxy cores and star-forming regions. The relic spiral arm has an ordered spiral 154 μ154~\mum B-field, while the 1111 cm B-field is radial. The 154 μ154~\mum B-field may be dominated by turbulent dynamos with high 12^{12}CO(1-0) velocity dispersion driven by star-forming regions, while the 1111 cm B-field is cospatial with high HI velocity dispersion driven by galaxy interaction. This result shows the dissociation between the warm gas mainly disturbed by the merger, and the dense gas still following the dynamics of the relic spiral arm. We find a 8.9\sim8.9 kpc scale ordered B-field connecting the two galaxies. The base of the tidal tail is cospatial with the HI and 12^{12}CO(1-0) emission and has compressed and/or sheared 154 μ154~\mum and 1111 cm B-fields driven by the merger. We suggest that amplify B-fields, with respect to the rest of the system and other spiral galaxies, may be supporting the gas flow between both galaxies and the tidal tail.Comment: 11 pages, 5 figures, Accepted for publication in ApJ Letter

    Transfusion related acute lung injury-TRALI: a review

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    Acute pulmonary damage caused by transfusion is characterized by the sudden onset of respiratory distress in newly transfused patients within 6 hours after the transfusion, bilateral infiltrative changes in chest X-ray, PaO2/FIO2 <300 mmHg, absence of other risk factors for acute lung injury and absence of signs suggesting cardiogenic origin of pulmonary edema. Being one of the most serious complications of blood transfusion, plasma is the most involved factor, although all blood components can cause it, and is caused by antigen reactions/leukocyte antibody and lipid activity with ability to modify the biological response on primitive leukocytes. The diagnosis is based on the integration of clinical, radiological and gasometric elements, ruling out the rest of the possible causes of acute lung injury. Its differential diagnosis should include hemodynamic overload, anaphylactic reaction, bacterial contamination of transfused blood products and transfusion hemolytic reaction. The treatment is supportive measures based on the needs and does not differ from the treatment of acute lung injury secondary to other etiologies, severe cases require endotracheal intubation and mechanical ventilation while the non-severe can be managed with oxygen therapy

    Structure, controlled release mechanisms and health benefits of pectins as an encapsulation material for bioactive food components

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    Encapsulation of food and feed ingredients is commonly applied to avoid the loss of functionality of bioactive food ingredients. Components that are encapsulated are usually sensitive to light, pH, oxygen or highly volatile. Also, encapsulation is also applied for ingredients that might influence taste. Many polymers from natural sources have been tested for encapsulation of foods. In the past few years, pectins have been proposed as emerging broadly applicable encapsulation materials. The reasons are that pectins are versatile and inexpensive, can be tailored to meet specific demands and provide health benefits. Emerging new insight into the chemical structure and related health benefits of pectins opens new avenues to use pectins in food and feed. To provide insight into their application potential, we review the current knowledge on the structural features of different pectins, their production and tailoring process for use in microencapsulation and gelation, and the impact of the pectin structure on health benefits and release properties in the gut, as well as processing technologies for pectin-based encapsulation systems with tailor-made functionalities. This is reviewed in view of application of pectins for microencapsulation of different sensitive food components. Although some critical factors such as tuning of controlled release of cargo in the intestine and the impact of the pectin production process on the molecular structure of pectin still need more study, current insight is that pectins provide many advantages for encapsulation of bioactive food and feed ingredients and are cost-effective

    Plan de negocio para la comercialización de una bebida instantánea a base de maca, kiwicha, cañihua y panela para exportación a EE. UU

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    Es indiscutible la importancia que tiene el mercado estadounidense para las exportaciones peruanas, el cual ocupa el segundo lugar entre los principales mercados de destino de nuestras exportaciones con una participación del 13% con respecto a las exportaciones totales. El TLC entre Perú y EEUU, no sólo permitió el ingreso de nuevos productos peruanos al mercado estadounidense, también repotenció los productos que ya se comercializaban antes. El impacto que ha tenido el Covid 19, mostrando que frágil puede ser la vida, ha acelerado la adopción de varios comportamientos del consumidor buscando tomar decisiones de estilo de vida saludables, los cuales se han desarrollado durante la pandemia y se están convirtiendo en un impulsor aún mayor de las elecciones de los consumidores. Por ello, nuestro trabajo de investigación tiene como objetivo determinar la viabilidad de un Plan de Negocio para exportar al mercado norteamericano una mezcla de harinas gelatinizadas compuesta por Maca, Cañihua, Kiwicha y Panela, que busca atender una necesidad que se ha incrementado como consecuencia de la pandemia que ha vivido el mundo, con productos naturales que favorezcan el fortalecimiento del organismo. El plan de negocio está desarrollado bajo el análisis y diagnóstico de la situación actual del macro y microentorno, evaluando las oportunidades y amenazas que el negocio enfrentaría en la inclusión al mercado de California por la demanda insatisfecha que podemos cubrir, desarrollando el plan estratégico que posicione a nuestro producto en el mercado estadounidense.The importance of the U.S. market for Peruvian exports is indisputable, as it is the second most important destination market for our exports, with a 13% share of total exports. The FTA between Peru and the United States not only allowed the entry of new Peruvian products into the U.S. market, but also boosted the products that were already traded before. The impact that Covid 19 has had, showing how fragile life can be, has accelerated the adoption of various consumer behaviors seeking to make healthy lifestyle choices, which have developed during the pandemic and are becoming an even greater driver of consumer choices. Therefore, our research work aims to determine the feasibility of a Business Plan to export to the North American market a mixture of gelatinized flours composed of Maca, Cañihua, Kiwicha and Panela, which seeks to meet a need that has increased as a result of the pandemic that the world has experienced, with natural products that favor the strengthening of the body. The business plan is developed under the analysis and diagnosis of the current situation of the macro and microenvironment, evaluating the opportunities and threats that the business would face in the inclusion to the California market due to the unsatisfied demand that we can cover, developing the strategic plan that positions our product in the U.S. market.Trabajo de investigació

    Risk of unintentional injuries in children and adolescents with ADHD and the impact of ADHD medications: A systematic review and meta-analysis

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    A systematic review with meta-analyses was performed to: 1) quantify the association between ADHD and risk of unintentional physical injuries in children/adolescents (¿risk analysis¿); 2) assess the effect of ADHD medications on this risk (¿medication analysis¿). We searched 114 databases through June 2017. For the risk analysis, studies reporting sex-controlled odds ratios (ORs) or hazard ratios (HRs) estimating the association between ADHD and injuries were combined. Pooled ORs (28 studies, 4,055,620 individuals without and 350,938 with ADHD) and HRs (4 studies, 901,891 individuals without and 20,363 with ADHD) were 1.53 (95% CI = 1.40,1.67) and 1.39 (95% CI = 1.06,1.83), respectively. For the medication analysis, we meta-analysed studies that avoided the confounding-by-indication bias [four studies with a self-controlled methodology and another comparing risk over time and groups (a ¿difference in differences¿ methodology)]. The pooled effect size was 0.879 (95% CI = 0.838,0.922) (13,254 individuals with ADHD). ADHD is significantly associated with an increased risk of unintentional injuries and ADHD medications have a protective effect, at least in the short term, as indicated by self-controlled studies
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