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Magnetic properties of EuFe0.5Mn0.5O3 complex perovskite
No full textIn this study, we determined the crystallographic, magnetization and electrical resistivity properties of a EuFe0.5Mn0.5O3 complex perovskite produced using a combustion synthesis method. The sample crystallized as an orthorhombic perovskite belonging to the Pbnm space group. Magnetization measurements indicated spin reorientation at 206 K and weak ferromagnetic-like ordering at low temperatures. Determining the magnetization as a function of the magnetic field demonstrated the presence of magnetic order, even at room temperature. Resistivity measurements indicated the existence of a small polaron conduction mechanism at high temperature. © 2020Consejo Nacional de Ciencia, Tecnología e Innovación Tecnológica - Concyte
Insulin-like growth factor I modulates sleep through hypothalamic orexin neurons
No full textAlthough sleep disturbances are common co-morbidities of metabolic diseases, the underlying processes linking both are not yet fully defined. Changes in the duration of sleep are paralleled by changes in the levels of insulin-like growth factor-I (IGF-I), an anabolic hormone that shows a circadian pattern in the circulation and activity-dependent entrance in the brain. However, the specific role, if any, of IGF-I in this universal homeostatic process remains poorly understood. We now report that the activity of orexin neurons, a discrete cell population in the lateral hypothalamus that is involved in the circadian sleep/wake cycle and arousal, is modulated by IGF-I. Furthermore, mice with blunted IGF-I receptor activity in orexin neurons have lower levels of orexin in the hypothalamus, show altered electro-corticographic patterns with predominant slow wave activity, and reduced onset-sleep latency. Collectively, these results extend the role in the brain of this pleiotropic growth factor to shaping sleep architecture through the regulation of orexin neurons. We speculate that poor sleep quality associated to diverse conditions may be related to disturbed brain IGF-I input to orexin neurons. © 2020 Federation of American Societies for Experimental BiologyFondo Nacional de Desarrollo Científico y Tecnológico - Fondecy
Screening of inmates transferred to Spain reveals a Peruvian prison as a reservoir of persistent Mycobacterium tuberculosis MDR strains and mixed infections
No full textIt is relevant to evaluate MDR-tuberculosis in prisons and its impact on the global epidemiology of this disease. However, systematic molecular epidemiology programs in prisons are lacking. A health-screening program performed on arrival for inmates transferred from Peruvian prisons to Spain led to the diagnosis of five MDR-TB cases from one of the biggest prisons in Latin America. They grouped into two MIRU-VNTR–clusters (Callao-1 and Callao-2), suggesting a reservoir of two prevalent MDR strains. A high-rate of overexposure was deduced because one of the five cases was coinfected by a pansusceptible strain. Callao-1 strain was also identified in 2018 in a community case in Spain who had been in the same Peruvian prison in 2002–5. A strain-specific-PCR tailored from WGS data was implemented in Peru, allowing the confirmation that these strains were currently responsible for the majority of the MDR cases in that prison, including a new mixed infection. © 2020, The Author(s).Consejo Nacional de Ciencia, Tecnología e Innovación Tecnológica - Concyte
Pest Incidence Prediction in Organic Banana Crops with Machine Learning Techniques
No full textOne of the main problems organic banana crops is the presence of pests, affecting crop yield, post-harvest and export fruit quality. In Piura (Peru), pests with the greatest presence are Thrips, Squamas, Black Weevil, etc. This article describes the development of a prediction model, based on a supervised machine learning algorithm: Logistic Regression and Support Vector Machine, which will estimate the future level of incidence (low and medium) of a specific pest. The model was designed including the input data (climate) that were obtained from a network of IoT sensors in-situ in the banana crop, and output data (level of incidence) that was collected with manual record and visual inspection. The model developed can predict pest incidence at 79% accuracy (with test data). These first results show feasibility to estimate in advance the incidence of pests in that crop. Future implementation of the model would help to farmers improving the pest management to their crops, increasing the production and quality of the product. © 2020 IEEE.Fondo Nacional de Desarrollo Científico y Tecnológico - Fondecy
Two Centuries of Hydroclimatic Variability Reconstructed From Tree-Ring Records Over the Amazonian Andes of Peru
No full textAlmost half of the tributaries of the Amazon River originate in the tropical Andes and support large populations in mountain regions and downstream areas. However, it is difficult to assess hydroclimatic conditions or to evaluate future scenarios due to the scarcity of long, high-quality instrumental records. Data from the Global Precipitation Climatology Project (GPCP) provide a complete record since 1979 and offer a good representation of rainfall over the tropical Andes. Longer records are needed to improve our understanding of rainfall variability and summer monsoon behavior at various scales. We developed the first annually resolved precipitation reconstruction for the tropical Andes in Peru, based on tree-ring chronologies of Cedrela and Juglans species. The annual (November–October) reconstruction extends the short instrumental records back to 1817, explaining 68% of the total variance of precipitation over the 1979–2007 calibration period. The reconstruction reveals the well-documented influence of El Niño-Southern Oscillation (ENSO) on Amazon Rainfall at interannual scales (~19% of total variance) and significant multidecadal variability with alternating periods of about 40 years (~13% of rainfall variability) related to the Atlantic Multidecadal Oscillation (AMO). Both oscillatory modes can explain dry and humid periods observed within the reconstruction and are likely associated with the negative trends of rainfall in the short instrumental records and the increased drought recurrence in recent decades. Our results show that montane tropical tree rings can be used to reconstruct precipitation with exceptionally high fidelity, characterize the interannual to multidecadal variability, and identify remote forcings in the hydroclimate over the Andean Amazon Basin of Peru. ©2020. American Geophysical Union. All Rights Reserved.Consejo Nacional de Ciencia, Tecnología e Innovación Tecnológica - Concyte
Feasibility of reverberant shear wave elastography for in vivo assessment of skeletal muscle viscoelasticity
No full textQuantifying the local stiffness of muscular tissue can be a useful tool for the improvement of diagnosis, treatment or monitoring of muscle abnormality-related diseases. Shear wave elastography techniques provide information about tissue stiffness by measuring the shear wave speed (SWS). Recently, a new framework involving the generation of a reverberant shear wave field that propagates in all directions within the medium was proposed. The aim of this study is to evaluate the feasibility of Reverberant Shear Wave Elastography (R-SWE) for the in vivo assessment of the viscoelastic properties of skeletal muscle, using the biceps brachii. Four experiments were performed at a vibration frequency range between 200-300 Hz in steps of 50 Hz, with the ultrasound transducer placed along the muscle fibers in both relaxed and contracted (MVC) states. The estimation of the SWS and a dispersion analysis using the Kelvin-Voigt Fractional Derivative (KVFD) model were carried out in order to assess the viscoelastic properties of the muscular tissue. Preliminary results show that R-SWE is feasible to use for the in vivo assessment of skeletal muscle by using a multifrequency approach. The viscoelastic parameters obtained by the KVFD curve-fitting and the dispersion analysis showed the expected differences between the relaxed and MVC states (i.e. a significant difference between the coefficient of viscosity and the dispersion rate of change). The SWS estimation also showed differences between the two states (e.g. a difference in SWS values of 35.52% at 300 Hz). © 2020 IEEE.Consejo Nacional de Ciencia, Tecnología e Innovación Tecnológica - Concyte
Leaching of a pyrite-based ore containing copper using sulfuric acid and hydrogen peroxide
No full textThe oxidation of sulfide-based ores is industrially relevant as it facilitates the extraction of valuable metals and eliminates undesired elements from an ore. Even though oxidation can be done thermally (pyrometallurgy), solution-based (hydrometallurgical) methods are currently sought as they represent a more sustainable option. Here, the leaching of a sulfide ore (32% Fe, 2% Cu) is investigated using a mixture of sulfuric acid and hydrogen peroxide (0.15 M H2SO4 and 0.5 M H2O2), in proportions forming a slurry 10% w/w. The leaching process is found to occur in two stages, the first corresponding to an exothermic, peroxide-mediated dissolution, and the second corresponding to an acid-mediated reaction, which appears to be thermoneutral. Control experiments performed with only peroxide confirm that this oxidant is involved in the first stage of the dissolution process. The leaching process leads to copper and iron dissolution (15% and 5%, respectively), as determined using atomic absorption spectrometry (AAS). The mass of pyrite dissolved is estimated from AAS measurements and, from the stoichiometry of the peroxide-mediated dissolution reaction, it is found that ~ 80% of the peroxide participates in the dissolution, with the other 20% being decomposed, in a reaction catalyzed by ferric (Fe+3) ions produced during the first stage of the dissolution. © 2020, Islamic Azad University.Consejo Nacional de Ciencia, Tecnología e Innovación Tecnológica - Concyte
Synthesis, characterization and application of a novel ion hybrid imprinted polymer to adsorb Cd(II) in different samples
No full textTwo new ionic imprinted hybrid polymers (IIHP) and their corresponding non imprinted hybrid polymers (NIHP) were synthesized. The prepared IIHP was highly selective to Cd2+. To prepare the IIHP, 1-vinylimidazole (VIN) was used as the functional monomer, (3-mercaptopropyl) trimethoxysilane (MP) or (3-aminopropyl) trimethoxysilane (AMP) was used as the functional organosilane, trimethylolpropane (TRIM) was used as the crosslinking agent, AIBN was used as a radical initiator and TEOS was used as a functional precursor. The functional monomer was selected considering calculations based on the density functional theory (DFT). The fabricated materials were characterized via field emission gun scanning electron microscopy (FEG-SEM), Fourier transform infrared spectroscopy (FTIR), energy dispersive X-ray spectroscopy (EDX) and thermogravimetric analysis (TGA). The maximum adsorption capacity of Cd2+ was achieved at a pH of 7.2 in the tris-HCl medium. The adsorption test indicated that the reaction followed pseudo second order kinetics, and the equilibrium sorption data fitted well into the Langmuir isotherm model. The relative selectivity coefficients of polymers IIHP-VIN-AMP and IIHP-VIN-MP, as evaluated in binary mixtures of Cd2+ and interferent cations (Pb2+, Zn2+, Hg2+, Cu2+, Ni2+, Ca2+, Mg2+, and Na+) at different molar ratios, were greater than one due to the presence of specific recognition sites for Cd2+ ions. Moreover, the selective materials exhibited a high reusability and reproducibility in the context of Cd2+ adsorption. These adsorbent materials, specifically IIHP-VIN-MP, exhibited a % removal efficiency of more than 90% for the Cd2+ in river water samples. © 2020 Elsevier Inc.Consejo Nacional de Ciencia, Tecnología e Innovación Tecnológica - Concyte
Attenuating effect of peruvian cocoa populations on the acute asthmatic response in brown norway rats
No full textCocoa contains bioactive components, which vary according to genetic and environmental factors. The present study aimed to ascertain the anti-allergic properties of native Peruvian cocoa populations (“Blanco de Piura” or BPC, “Amazonas Peru” or APC, “Criollo de Montaña” or CMC, “Chuncho” or CCC, and an ordinary cocoa or OC). To do so, after an initial in vitro approach, an in vivo study focused on the induction of an anaphylactic response associated with allergic asthma in Brown Norway rats was carried out. Based on their polyphenol content, antioxidant activity and in vitro effects, the APC and CMC were selected to be included in the in vivo study. Cocoa diets were tested in a model of allergic asthma in which anaphylactic response was assessed by changes in body temperature, motor activity and body weight. The concentration of specific immunoglobulin E (IgE), mast cell protease and leukotrienes was also quantified in serum and/or bronchoalveolar lavage fluid. CMC and OC populations exhibited a protective effect on the allergic asthma rat model as evidenced by means of a partial protection against anaphylactic response and, above all, in the synthesis of IgE and the release of mast cell protease.Consejo Nacional de Ciencia, Tecnología e Innovación Tecnológica - Concyte
Taxonomic revaluation of the Polylepis pauta and P. sericea (Rosaceae) from Ecuador
No full textWe conducted a taxonomic revaluation of the Polylepis pauta and P. sericea complexes in Ecuador, recognizing five species, three of which are described as new: Polylepis humboldtii sp. nov., P. loxensis sp. nov., P. longipilosa sp. nov., P. ochreata, and P. pauta. We provide descriptions of all species, full specimen citations, and updated keys to genus Polylepis in Ecuador and to the P. pauta and P. sericea complexes in general. Copyright © 2020 Magnolia PressFondo Nacional de Desarrollo Científico y Tecnológico - Fondecy