Imbedding estimates and elliptic equations with discontinuous coefficients in unbounded domains

In this paper we deal with the multiplication operator u ∈ W^{k,p} (Ω) → gu ∈ L^q (Ω), with g belonging to a space of Morrey type. We apply our results in order to establish an a-priori bound for the solutions of the Dirichlet problem concerning elliptic equations with discontinuous coefficients

Non-equilibrium effects on charge and energy partitioning after an interaction quench

Charge and energy fractionalization are among the most intriguing features of interacting onedimensional fermion systems. In this work we determine how these phenomena are modified in the presence of an interaction quench. Charge and energy are injected into the system suddenly after the quench, by means of tunneling processes with a non-interacting one-dimensional probe. Here, we demonstrate that the system settles to a steady state in which the charge fractionalization ratio is unaffected by the pre-quenched parameters. On the contrary, due to the post-quench nonequilibrium spectral function, the energy partitioning ratio is strongly modified, reaching values larger than one. This is a peculiar feature of the non-equilibrium dynamics of the quench process and it is in sharp contrast with the non-quenched case, where the ratio is bounded by one.Comment: 12 pages, 4 figure

A strong maximum principle for linear elliptic operators

This paper is concerned with a maximum principle for subsolutions, in the class W^{2,p}_loc, of second order linear elliptic equations in nondivergence form in arbitrary open (bounded or not) subsets of R^n, n >=2, when p > n/2

Liquid chromatographic strategies for separation of bioactive compounds in food matrices

Nowadays, there is an increasing attention for nutraceuticals and, in general, bioactive compounds naturally present in food. Indeed, the possibility of preserving human health and preventing disease (e.g., cardiovascular diseases, cancer etc.) by the intake of healthy food is attractive for both consumers and food industries. In turn, research in this field was also prompted significantly, with the aim of characterizing these bioactive compounds and ascribe to them a specific activity. The bioactive compounds can belong to several chemical classes. However, their chemical diversity and presence in complex matrices, such as food, make it challenging both their isolation and characterization. To tackle this issue, efficient separation systems are needed, which are mainly based on chromatography. In this context, this mini-review aims to provide the reader with an overview of the most relevant and recent approaches for the separation of the most common bioactive compounds in food, in particular polyphenols, phenols, carotenoids, and peptides, by liquid chromatography approaches. © 2018 by the authors

Determination of permethrin and its metabolite in brains and urines of rats by GC-ECD and GC-MS

Synthetic pyrethroids are pesticides derived from naturally occurring pyrethrins, taken from pyrethrum of dried Chrysanthemum flowers. Pyrethroid insecticides are one of the most commonly used residential and agricultural insecticides. Many pyrethroids can significantly harm the nervous system. Permethrin could be one of the factors involved in the onset of neurodegenerative diseases. The present study aims to evaluate in brain, the effect that can induce the exposure to permethrin, during early life of female rats (from 6 to 21 days of life). Therefore, have been examined the concentrations of permethrin and its main metabolite (3-PBA) in the brain and urine in female rats sacrificed the day after and 14 days after treating. The different concentrations of permethrin and 3-PBA (after 24h and after 14 days in the end of treatment) were obtained using two different methods. The evaluation of permethrin by liquid-liquid extraction and GC-ECD was performed. The levels of the 3-PBA (in urine and brains) were obtained by SPE procedure and GC-MS using the 2- PBA as internal standard

A rapid magnetic solid phase extraction method followed by liquid chromatography-tandem mass spectrometry analysis for the determination of mycotoxins in cereals

Mycotoxins can contaminate various food commodities, including cereals. Moreover, mycotoxins of different classes can co-contaminate food, increasing human health risk. Several analytical methods have been published in the literature dealing with mycotoxins determination in cereals. Nevertheless, in the present work, the aim was to propose an easy and effective system for the extraction of six of the main mycotoxins from corn meal and durum wheat flour, i.e., the main four aflatoxins, ochratoxin A, and the mycoestrogen zearalenone. The developed method exploited magnetic solid phase extraction (SPE), a technique that is attracting an increasing interest as an alternative to classical SPE. Therefore, the use of magnetic graphitized carbon black as a suitable extracting material was tested. The same magnetic material proved to be effective in the extraction of mycoestrogens from milk, but has never been applied to complex matrices as cereals. Ultra high-performance liquid chromatography tandem mass spectrometry was used for detection. Recoveries were > 60% in both cereals, even if the matrix effects were not negligible. The limits of quantification of the method results were comparable to those obtained by other two magnetic SPE-based methods applied to cereals, which were limited to one or two mycotoxins, whereas in this work the investigated mycotoxins belonged to three different chemical classes

"A escola e o mundo do aluno: estudos sobre a construção social do aluno e o papel institucional da escola", de Marcelo Baumann Burgos (coord.) Español.

Reseña por Ana Maria Cavalier

“A escola e o mundo do aluno: estudos sobre a construção social do aluno e o papel institucional da escola”, de Marcelo Baumann Burgos (coord.). Português.

Resenha por Ana Maria Cavalier

Apresentação da Seção Temática – Tempo de Escola

Foreword to the Thematic Section.Apresentação

O COLÉGIO PEDRO II ENCONTRA O SÉCULO XXI

A decisão de dedicar um número da Revista Contemporânea de Educação ao Colégio Pedro II deve-se à importância dessa instituição federal de ensino para a história da educação brasileira e, particularmente, para a história da cidade do Rio de Janeiro. O Colégio Pedro II é parte da vida da atual capital do estado. Escola secular, fundada em 1837, recupera, em 1911, o nome Pedro II, após uma longa crise no início da República, quando passou a se chamar Ginásio Nacional. Ao longo de todos esses anos, recebeu gerações de cariocas, e de brasileiros de diferentes regiões, a princípio quase que exclusivamente ligados à elite política e intelectual1, e, posteriormente, oriundos de segmentos diversificados da população. Filhos de pequenos comerciantes nos anos 1940, da classe média urbana instruída e liberal nos anos 1950/60, das camadas populares a partir de 1984, quando da implantação do primeiro segmento do ensino fundamental com ingresso na classe de alfabetização feito por sorteio universal