Direct measurements of conventional and anisotropic magnetocaloric effect in binary RAI(2) single crystals

FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESPCOORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIOR - CAPESCONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQWe report on specific heat and magnetocaloric effect (MCE) measurements in single crystals of HoAl2, DyAl2, and TbAl2 measured by a heat flux technique using Peltier devices. Those compounds order ferromagnetically at 31 K, 61 K, and 106 K respectively, and present a spin reorientation transition (SRT) below T-C. We study the dependence of the SRT with magnetic field and temperature by means of specific heat measurements performed in single crystals oriented at the [100], [110], and [111] directions with the aid of calculations using a simple model. We obtained the conventional MCE for HoAl2 and TbAl2 and also the anisotropic version of the effect obtained indirectly from the specific heat for TbAl2 and DyAl2. We also present the results for a direct determination of the anisotropic MCE for DyAl2 by measuring the heat flux generated by a rotation of the single crystal under constant field.1212119FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESPCOORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIOR - CAPESCONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQFUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESPCOORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIOR - CAPESCONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQSem informaçãoSem informaçãoSem informaçãoWe would like to thank the financial support from the Brazilian agencies FAPESP, Capes, CNPq, and FAEPEX-Unicamp

The Creation of Defects with Core Condensation

Defects in superfluid 3He, high-Tc superconductors, QCD colour superfluids and cosmic vortons can possess (anti)ferromagnetic cores, and their generalisations. In each case there is a second order parameter whose value is zero in the bulk which does not vanish in the core. We examine the production of defects in the simplest 1+1 dimensional scalar theory in which a second order parameter can take non-zero values in a defect core. We study in detail the effects of core condensation on the defect production mechanism.Comment: 9 pages, 7 figures, small corrections, 2 references added, final version to be published in PR

Anthropological and socioeconomic factors contributing to global antimicrobial resistance: a univariate and multivariable analysis

Background Understanding of the factors driving global antimicrobial resistance is limited. We analysed antimicrobial resistance and antibiotic consumption worldwide versus many potential contributing factors. Methods Using three sources of data (ResistanceMap, the WHO 2014 report on antimicrobial resistance, and contemporary publications), we created two global indices of antimicrobial resistance for 103 countries using data from 2008 to 2014: Escherichia coli resistance—the global average prevalence of E coli bacteria that were resistant to third-generation cephalosporins and fluoroquinolones, and aggregate resistance—the combined average prevalence of E coli and Klebsiella spp resistant to third-generation cephalosporins, fluoroquinolones, and carbapenems, and meticillin-resistant Staphylococcus aureus. Antibiotic consumption data were obtained from the IQVIA MIDAS database. The World Bank DataBank was used to obtain data for governance, education, gross domestic product (GDP) per capita, health-care spending, and community infrastructure (eg, sanitation). A corruption index was derived using data from Transparency International. We examined associations between antimicrobial resistance and potential contributing factors using simple correlation for a univariate analysis and a logistic regression model for a multivariable analysis. Findings In the univariate analysis, GDP per capita, education, infrastructure, public health-care spending, and antibiotic consumption were all inversely correlated with the two antimicrobial resistance indices, whereas higher temperatures, poorer governance, and the ratio of private to public health expenditure were positively correlated. In the multivariable regression analysis (confined to the 73 countries for which antibiotic consumption data were available) considering the effect of changes in indices on E coli resistance (R2 0·54) and aggregate resistance (R2 0·75), better infrastructure (p=0·014 and p=0·0052) and better governance (p=0·025 and p<0·0001) were associated with lower antimicrobial resistance indices. Antibiotic consumption was not significantly associated with either antimicrobial resistance index in the multivariable analysis (p=0·64 and p=0·070). Interpretation Reduction of antibiotic consumption will not be sufficient to control antimicrobial resistance because contagion—the spread of resistant strains and resistance genes—seems to be the dominant contributing factor. Improving sanitation, increasing access to clean water, and ensuring good governance, as well as increasing public health-care expenditure and better regulating the private health sector are all necessary to reduce global antimicrobial resistance

The physical properties of Gd3Ru: a real candidate for a practical cryogenic refrigerator

FAPESP - FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULOCNPQ - CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICOCAPES - COORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIORThe magnetization, the specific heat, and the magnetocaloric effect (MCE) for Gd3Ru are presented as function of temperature at different magnetic fields. The results show a maximum entropy change -Delta S = 30 J/kg K @ 5 T, which is the highest value for the R3M compounds. With a non-hysteretic transition of first order type at T-C = 54 K, it presents a temperature change Delta T-max = 5.7K around 59K with a refrigerating cooling power of 700 J/kg and these results are comparable to values found for giant MCE materials. This compound is stable and able to operate at temperatures between 90K and 40K with a minimum -Delta S = 5 J/kg K. These figures were obtained by sweeping the magnetic field without using sample preparation routines. This methodology is appropriate to evaluate the MCE for the cycling process of a cryogenic magnetic refrigerator. (C) 2015 AIP Publishing LLC.The magnetization, the specific heat, and the magnetocaloric effect (MCE) for Gd3Ru are presented as function of temperature at different magnetic fields. The results show a maximum entropy change -Delta S = 30 J/kg K @ 5 T, which is the highest value for the R3M compounds. With a non-hysteretic transition of first order type at T-C = 54 K, it presents a temperature change Delta T-max = 5.7K around 59K with a refrigerating cooling power of 700 J/kg and these results are comparable to values found for giant MCE materials. This compound is stable and able to operate at temperatures between 90K and 40K with a minimum -Delta S = 5 J/kg K. These figures were obtained by sweeping the magnetic field without using sample preparation routines. This methodology is appropriate to evaluate the MCE for the cycling process of a cryogenic magnetic refrigerator.1061914FAPESP - FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULOCNPQ - CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICOCAPES - COORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIORFAPESP - FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULOCNPQ - CONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICOCAPES - COORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIORSem informaçãoSem informaçãoSem informaçãoThe authors thank Professor Lisandro Cardoso and Hugo Freitas for the X-Ray diffractograms and also Gustavo Lombardi for the assistance in the sample preparation. We acknowledge the financial support provided by the Brazilian agencies FAPESP, FAEPEX-Unicamp, CNPq, and CAPES

Utilización de redes neuronales para formular grasas técnicas

Neural networks are a branch of artificial intelligence based on the structure and development of biological systems, having as its main characteristic the ability to learn and generalize knowledge. They are used for solving complex problems for which traditional computing systems have a low efficiency. To date, applications have been proposed for different sectors and activities. In the area of fats and oils, the use of neural networks has focused mainly on two issues: the detection of adulteration and the development of fatty products. The formulation of fats for specific uses is the classic case of a complex problem where an expert or group of experts defines the proportions of each base, which, when mixed, provide the specifications for the desired product. Some conventional computer systems are currently available to assist the experts; however, these systems have some shortcomings. This article describes in detail a system for formulating fatty products, shortenings or special fats, from three or more components by using neural networks (MIX). All stages of development, including design, construction, training, evaluation, and operation of the network will be outlined.Las redes neuronales son una rama de la inteligencia artificial basadas en la estructura y funcionamiento de sistemas biológicos, teniendo como principal característica la capacidad de aprender y generalizar conocimiento. Estas son utilizadas en la resolución de problemas complejos, en los cuales los sistemas computacionales tradicionales presentan una eficiencia baja. Hasta la fecha, han sido propuestas aplicaciones para los más diversos sectores y actividades. En el área de grasas y aceites, la utilización de redes neuronales se ha concentrado principalmente en dos asuntos: la detección de adulteraciones y la formulación de productos grasos. La formulación de grasas para uso específico es el caso clásico de problema complejo donde un experto o grupo de expertos definen las proporciones de cada base, que al ser mezcladas proporcionaran características especificadas para el producto deseado. Algunos sistemas computacionales convencionales están disponibles actualmente para auxiliar a los expertos, sin embargo, estos sistemas presentan algunas deficiencias. En este artículo será descrito con detalles, un sistema para la formulación de productos grasos por redes neuronales (MIX) a partir de 3 o más componentes. Todas las etapas del desarrollo, incluyendo el diseño, construcción, entrenamiento, evaluación y operación de la red serán mostradas

Determination of the magnetocaloric entropy change by field sweep using a heat flux setup

FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESPCONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQCOORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIOR - CAPESWe report on a simple setup using a heat flux sensor adapted to a Quantum Design Physical Property Measurement System to determine the magnetocaloric entropy change (Delta S). The major differences for the existing setups are the simplicity of this assembly and the ease to obtain the isothermal entropy change either by a field sweep or a temperature sweep process. We discuss the use of these two processes applied to Gd and Gd5Ge2Si2 samples. The results are compared to the temperature sweep measurements and they show the advantages of this setup and of the field sweep procedure. We found a significant reduction of DS and on the refrigerating cooling power (RCP) at low field changes in a field sweep process when the sample is not driven to the same initial state for each temperature. We show that the field sweep process without any measuring protocol is the only correct way to experimentally determine DS and RCP for a practical regenerative refrigerator.105715FUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESPCONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQCOORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIOR - CAPESFUNDAÇÃO DE AMPARO À PESQUISA DO ESTADO DE SÃO PAULO - FAPESPCONSELHO NACIONAL DE DESENVOLVIMENTO CIENTÍFICO E TECNOLÓGICO - CNPQCOORDENAÇÃO DE APERFEIÇOAMENTO DE PESSOAL DE NÍVEL SUPERIOR - CAPESSem informaçãoSem informaçãoSem informaçã

Transport properties of moderately disordered UCu4_4Pd

We present a detailed study on the (magneto)transport properties of as-cast and heat treated material UCu$_4$Pd. We find a pronounced sample dependence of the resistivity $\rho$ of as-cast samples, and reproduce the annealing dependence of $\rho$. In our study of the Hall effect we determine a metallic carrier density for all samples, and a temperature dependence of the Hall constant which is inconsistent with the Skew scattering prediction. The magnetoresistive response is very small and characteristic for spin disorder scattering, suggesting that overall the resistivity is controlled mostly by nonmagnetic scattering processes. We discuss possible sources for the temperature and field dependence of the transport properties, in particular with respect to quantum criticality and electronic localization effects.Comment: 11 pages, 9 figures, submitted PR