Ferroelectric properties of Bi0.5(Na0.8K0.2)0.5TiO3 ceramics

Different processing conditions and the effect of secondary phases on ferroelectric properties of Bi0.5(Na0.8K0.2)0.5TiO3 (BNKT) are studied. Ceramic powders are prepared by solid state reaction and different sintering temperatures (temperatures between 1075 and 1150ºC) are analyzed. Finally, samples are characterized by X-ray diffraction, Raman microspectroscopy, Scanning Electron Microscopy, impedance spectroscopy, and density measurements. Through XRD patterns, the perovskite structure is stabilized; together with small peaks corresponding to a secondary phase associated with K2-xNaxTi6O13 phase. Moreover, the content of the secondary phase, d33 piezoelectric constant and dielectric properties increase with sintering temperature.Fil: Camargo, Javier Eduardo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y Tecnología de Materiales. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones en Ciencia y Tecnología de Materiales; ArgentinaFil: Ramajo, Leandro Alfredo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y Tecnología de Materiales. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones en Ciencia y Tecnología de Materiales; ArgentinaFil: Rubio Marcos, Fernando. Instituto de Ceramica y Vidrio de Madrid; EspañaFil: Castro, Miriam Susana. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y Tecnología de Materiales. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones en Ciencia y Tecnología de Materiales; Argentin

The Fubini's Theorem for the Even Index Lie Subgroup

In this paper we present a new proof to generalize the Fubini's Theorem for the even index subgroup of a compact Lie group, using a recent result on the semi-direct product of groups. We also present some applications of this result for the invariant theory.Comment: 10 page

Brazilian National Defence Policy: foreign policy, national security, economic growth, and technological innovation

With the world’s ninth largest economy and comprising nearly 60% of South America’s GDP, 47% of its territory, and 49% of its population, Brazil has become a regional power and an important actor in world affairs over recent decades. This scenario has led the government to re-evaluate its role in the world order, resulting in the enactment of the National Defence Policy, whose objective was to consolidate the country as a regional power while at the same time addressing national security issues, promoting economic development through a series of defence programmes, restructuring the defence industrial base, fostering innovation through technology and knowledge transfer to Brazil, and indigenous research and development. However, the policy’s implementation suffers from several challenges discussed in this article, which may test the capability and competence of Brazilian policymakers, military, industrialists, and other individuals and organisations involved in its implementation

Release kinetics of multi-nutrients from volcanic rock mining by-products: evidences for their use as a soil remineralizer

Great quantities of stone by-products are stored alongside different exploiting mines in south Brazil, which are becoming an unsustainable environmental issue. Powder materials of andesite and dacite rocks were obtained from two mining companies of Southern Brazil. The particle size classification of the materials was determined by sieving. The X-ray diffraction (XRD) technique was used to identify the mineral phases of the by-products and X-ray fluorescence (XRF) was applied to determine their chemical compositions. The concentrations of calcium (Ca), potassium (K), magnesium (Mg), phosphorus (P) and silicon (Si) released by the by-products were determined by inductively coupled plasma atomic emission spectrometry (ICP-AES). Dissolution rates of andesite and dacite rocks were measured in Milli-Q water, and in solutions of 0.1 mol L−1 citric acid, and Milli-Q water acidified with 0.5 mol L−1 acetic acid, as a function of reaction times at 24–96 h (short-term), and at 96–5760 h (long-term). The solutions were agitated continuously on a mechanical rotatory shaker at room temperature. The parabolic diffusion, simplified Elovich, and power function models were applied at both time slots of solid-solution reaction. The results indicated that the relationships of quantity of released multi-nutrients were well described by power equation: ln qt = ln a + b ln t. Dissolution rates were obtained based on the release of Ca, K, Mg, P and Si at a steady state under far from equilibrium conditions. Dissolution rates of both by-products were not affected, within the experimental uncertainty, by Milli-Q water. Although the by-products dissolution rates were unaffected by Milli-Q water, its rates are increased along the time. The dissolution of the by-products minerals was significantly affected by the pH of the solutions. The multi-elements release by both by-products in 0.1 mol L−1 citric acid solution was significantly larger than another solutions, indicating that exchangeable cations were readily available in citric acid solution. The results obtained from power function model in two reaction time intervals can contribute to estimate the multi-nutrients-supplying power of by-products to soil. The present study provides both to solving an environmental issue associated with Brazilian rock exploitation and to create an alternative for soil fertilization and a more sustainable agriculture

Early Identification of Abused Domains in TLD through Passive DNS Applying Machine Learning Techniques

DNS is vital for the proper functioning of the Internet. However, users use this structure for domain registration and abuse. These domains are used as tools for these users to carry out the most varied attacks. Thus, early detection of abused domains prevents more people from falling into scams. In this work, an approach for identifying abused domains was developed using passive DNS collected from an authoritative DNS server TLD along with the data enriched through geolocation, thus enabling a global view of the domains. Therefore, the system monitors the domain’s first seven days of life after its first DNS query, in which two behavior checks are performed, the first with three days and the second with seven days. The generated models apply the machine learning algorithm LightGBM, and because of the unbalanced data, the combination of Cluster Centroids and K-Means SMOTE techniques were used. As a result, it obtained an average AUC of 0.9673 for the three-day model and an average AUC of 0.9674 for the seven-day model. Finally, the validation of three and seven days in a test environment reached a TPR of 0.8656 and 0.8682, respectively. It was noted that the system has a satisfactory performance for the early identification of abused domains and the importance of a TLD to identify these domains

SER PARAGUAIO NO MATO GROSSO DO SUL: DA MIGRAÇÃO À CONSTRUÇÃO DE UMA IDENTIDADE TRANSFRONTEIRIÇA

As migrações em áreas de fronteira adquirem crescente relevância no mundo contemporâneo. No Brasil, particularmente o Mato Grosso do Sul, tem sua formação socioespacial vinculada à migração paraguaia. Este processo é aqui analisado sob a perspectiva neocolonial que leva em conta o conflito de identidades territoriais e a construção de novas territorialidades pelo trânsito cultural. Com isso, buscamos revelar esta identidade transfronteiriça no município de Dourados

Feminilidade e a sistematização kleiniana: o corpo materno como palco da gênese psíquica

This study aims at investigating the theme referred to as femininity as shown in the book The psychoanalysis of children, by Melanie Klein. The perspective herein is that this author transposes the classical logic of the subjective constitution of the Western world, i.e., that the phallus/masculine would be the starting point for sexual differentiation. In epistemological terms, the Kleinian notion of femininity, used in this investigation as a lens for reading such work, shall allow us to better understand the basis of the author’s conception of mother, in addition to revising the Oedipus complex and the proposition of new concepts.Propomos investigar o tema da feminilidade presente no livro A psicanálise de crianças de Melanie Klein. Nossa concepção é a de que essa autora invertera a lógica clássica da constituição subjetiva do mundo ocidental: a de que o falo/masculino seria o ponto de partida para as diferenciações sexuais. A noção kleiniana de feminilidade que utilizaremos como lente para nossa leitura dessa obra nos permitiria, em termos epistemológicos, compreender melhor como se fundamentou a concepção dessa autora sobre o materno e a possibilidade de suas revisões sobre o complexo de Édipo e a proposição de novos conceitos.      El presente estudio tiene como objetivo investigar el tema de la feminidad, que se presenta en el libro El psicoanálisis de niños de Melanie Klein. La concepción aquí es que la autora invierte la lógica clásica de la constitución subjetiva del mundo occidental, es decir, que el falo/masculino sería el punto de partida paralas diferenciaciones sexuales. En términos epistemológicos, la noción kleiniana de feminidad utilizada en esta investigación nos permitirá comprender mejor cómo se basó la concepción de la autora sobre lo materno, además de revisar el complejo de Edipo y la proposición de nuevos conceptos