Doping of inorganic materials in microreactors – preparation of Zn doped Fe₃O₄ nanoparticles

Microreactor systems are now used more and more for the continuous production of metal nanoparticles and metal oxide nanoparticles owing to the controllability of the particle size, an important property in many applications. Here, for the first time, we used microreactors to prepare metal oxide nanoparticles with controlled and varying metal stoichiometry. We prepared and characterised Zn-substituted Fe₃O₄ nanoparticles with linear increase of Zn content (ZnxFe₃−xO₄ with 0 ≤ x ≤ 0.48), which causes linear increases in properties such as the saturation magnetization, relative to pure Fe₃O₄. The methodology is simple and low cost and has great potential to be adapted to the targeted doping of a vast array of other inorganic materials, allowing greater control on the chemical stoichiometry for nanoparticles prepared in microreactors

Medición de la conductividad térmica en materiales aislantes bajo régimen de flujo de calor no estacionario

A device to measure thermal conductivity in thermal insulating solid materials commonly used in buildings was developed following a one-dimensional model of heat flow through a plate of the material to be evaluated. The temperature gradient between the plate faces was measured as a function of time by means of a set of type T thermocouples. A circuit with commercial microcontrollers was designed to control the instrument’s mechanisms, the acquisition and the treatment of data. In preliminary tests with some materials, thermal conductivity values similar to those reported in the literature were obtained by using a linear adjustment with R values between 0.90 and 0.98. This device turns out to be a good instrument for measuring thermal conductivity because it has several advantages, such as: easy implementation, sample size, measurement method; compared to those using traditional methods.Se desarrolló un dispositivo para medir la conductividad térmica en materiales sólidos para aislamiento térmico de uso común en edificaciones, siguiendo un modelo unidimensional de flujo de calor que atraviesa una placa del material a evaluar. Se mide el gradiente de temperatura entre las caras de la placa en función del tiempo, usando un arreglo diferencial de termopares tipo T. Para el control de los mecanismos del instrumento, la adquisición y tratamiento de los datos, se diseñó un circuito con microcontroladores comerciales. En ensayos previos con algunos materiales se obtuvieron valores la conductividad térmica similares a los reportados en la literatura utilizando un ajuste lineal con valores de R entre 0.90 y 0.98. El dispositivo obtenido representa un instrumento útil para la medición de la conductividad térmica, destacando entre sus ventajas: la fácil construcción, el tamaño de las muestras a evaluar y el método de medida, comparado con los métodos tradicionales para medir este parámetro

The costs of preventing and treating chagas disease in Colombia

Background: The objective of this study is to report the costs of Chagas disease in Colombia, in terms of vector disease control programmes and the costs of providing care to chronic Chagas disease patients with cardiomyopathy. Methods: Data were collected from Colombia in 2004. A retrospective review of costs for vector control programmes carried out in rural areas included 3,084 houses surveyed for infestation with triatomine bugs and 3,305 houses sprayed with insecticide. A total of 63 patient records from 3 different hospitals were selected for a retrospective review of resource use. Consensus methodology with local experts was used to estimate care seeking behaviour and to complement observed data on utilisation. Findings: The mean cost per house per entomological survey was $4.4 (in US$ of 2004), whereas the mean cost of spraying a house with insecticide was $27. The main cost driver of spraying was the price of the insecticide, which varied greatly. Treatment of a chronic Chagas disease patient costs between$46.4 and $7,981 per year in Colombia, depending on severity and the level of care used. Combining cost and utilisation estimates the expected cost of treatment per patient-year is$1,028, whereas lifetime costs averaged $11,619 per patient. Chronic Chagas disease patients have limited access to healthcare, with an estimated 22% of patients never seeking care. Conclusion: Chagas disease is a preventable condition that affects mostly poor populations living in rural areas. The mean costs of surveying houses for infestation and spraying infested houses were low in comparison to other studies and in line with treatment costs. Care seeking behaviour and the type of insurance affiliation seem to play a role in the facilities and type of care that patients use, thus raising concerns about equitable access to care. Preventing Chagas disease in Colombia would be cost-effective and could contribute to prevent inequalities in health and healthcare.Wellcome Trus

Implementación de servicios de infraestructura IT en Zentyal Server 5.0

En este artículo se busca abordar la importancia de Zentyal Server como plataforma para la administración de la Infraestructura IT dentro de una organización que quiera estar a la vanguardia tecnológica, donde se explicará de manera técnica la implementación de esta importante herramientaThis article seeks to address the importance of Zentyal Server as a platform for the administration of IT Infrastructure within an organization that wants to be at the forefront of technology, where the implementation of this important tool will be explained in a technical manner

Effect of inorganic ions on pyrite catalyzed Fenton reaction

© 2018, Avestia Publishing. Industrial wastewaters contain not only organic pollutants but also considerable amounts of inorganic ions that may affect the efficiency of wastewater remediation processes. Thus, it is important to study the influence of such ions in the respective chemical reactions. Here we performed Fenton reactions for the decolourization of Rhodamine B dye using the naturally occurring mineral pyrite (FeS2) as heterogeneous catalyst in presence of different inorganic ions that are typically present in wastewater. Additionally, the effect of milling time of the pyrite powder on the performance of the heterogeneous Fenton reaction has also been investigated

Highlights from the Pierre Auger Observatory

The Pierre Auger Observatory is the world's largest cosmic ray observatory. Our current exposure reaches nearly 40,000 km$^2$ str and provides us with an unprecedented quality data set. The performance and stability of the detectors and their enhancements are described. Data analyses have led to a number of major breakthroughs. Among these we discuss the energy spectrum and the searches for large-scale anisotropies. We present analyses of our X$_{max}$ data and show how it can be interpreted in terms of mass composition. We also describe some new analyses that extract mass sensitive parameters from the 100% duty cycle SD data. A coherent interpretation of all these recent results opens new directions. The consequences regarding the cosmic ray composition and the properties of UHECR sources are briefly discussed.Comment: 9 pages, 12 figures, talk given at the 33rd International Cosmic Ray Conference, Rio de Janeiro 201

A search for point sources of EeV photons

Measurements of air showers made using the hybrid technique developed with the fluorescence and surface detectors of the Pierre Auger Observatory allow a sensitive search for point sources of EeV photons anywhere in the exposed sky. A multivariate analysis reduces the background of hadronic cosmic rays. The search is sensitive to a declination band from -85{\deg} to +20{\deg}, in an energy range from 10^17.3 eV to 10^18.5 eV. No photon point source has been detected. An upper limit on the photon flux has been derived for every direction. The mean value of the energy flux limit that results from this, assuming a photon spectral index of -2, is 0.06 eV cm^-2 s^-1, and no celestial direction exceeds 0.25 eV cm^-2 s^-1. These upper limits constrain scenarios in which EeV cosmic ray protons are emitted by non-transient sources in the Galaxy.Comment: 28 pages, 10 figures, accepted for publication in The Astrophysical Journa

Reconstruction of inclined air showers detected with the Pierre Auger Observatory

We describe the method devised to reconstruct inclined cosmic-ray air showers with zenith angles greater than $60^\circ$ detected with the surface array of the Pierre Auger Observatory. The measured signals at the ground level are fitted to muon density distributions predicted with atmospheric cascade models to obtain the relative shower size as an overall normalization parameter. The method is evaluated using simulated showers to test its performance. The energy of the cosmic rays is calibrated using a sub-sample of events reconstructed with both the fluorescence and surface array techniques. The reconstruction method described here provides the basis of complementary analyses including an independent measurement of the energy spectrum of ultra-high energy cosmic rays using very inclined events collected by the Pierre Auger Observatory.Comment: 27 pages, 19 figures, accepted for publication in Journal of Cosmology and Astroparticle Physics (JCAP