Assessment of daily dietary intake of Hg and some essential elements in diets of children from the Amazon region

Summary Daily dietary intake of Hg and some essential elements in diets of children from communities in the Jaú National Park, Amazon region, were assessed. Diet samples were analyzed for total Hg content using cold vapor atomic absorption spectrometry and Ca, Fe, K, Na, Se and Zn contents by instrumental neutron activation analysis. The weekly tolerable provisional intake for Hg in the communities studied varied from 13 to 57 mg of Hg per kg of body weight, exceeding the limit of 5 mg ^. kg^-1 set by the WHO. Comparison of the daily dietary intake values to the new Dietary Reference Intakes (4-8 years), showed prevalence of inadequacy.     

A polyhedral study of the semi-continuous knapsack problem

We study the convex hull of the feasible set of the semi-continuous knapsack problem, in which the variables belong to the union of two intervals. Such structure arises in a wide variety of important problems, e.g. blending and portfolio selection. We show how strong inequalities valid for the semi-continuous knapsack polyhedron can be derived and used in a branch-and-cut scheme for problems with semi-continuous variables. To demonstrate the effectiveness of these inequalities, which we call collectively semi-continuous cuts, we present computational results on real instances of the unit commitment problem, as well as on a number of randomly generated instances of linear programming with semi-continuous variables.     

Colloidal semiconductor quantum dots: Potential tools for new diagnostic methods

We present and discuss the application of colloidal semiconductor quantum dots for diagnostic purposes, with special emphasis for cancer. We prepared and applied core-shell cadmium sulfide-cadmium hydroxide (CdS/Cd(OH)₂) semiconductor quantum dots in aqueous medium. Tissue and cells labeling was evaluated by laser scanning confocal microscopy as well as by conventional fluorescence microscopy. The procedure presented in this work, shown to be a promising tool for fast, low-cost and precise cancer diagnostic protocols.     

The first and second ionization energies of the element 119: absolute hardness and Mulliken electronegativity for the cation 119+ based on an empirical equation involving absolute hardness

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High performance liquid chromatography applied in hormone contaminations detection: A scoping review in ecotoxicology

The present work shows a systematic overview of studies about the methods used to quantify the estrogen 17β-estradiol, estrone, estriol and 17α-ethynylestradiol in surface water through high performance liquid chromatography. The PubMed, Web of Science, and Scopus databases were searched. Articles from the last 10 years have been selected, and only in English language. Literature search strategy involved the keywords “estradiol”, “High Performance Liquid Chromatography”, “HPLC” and “water”. Initially, 955 articles were found. After applying the exclusion criteria (repetition, objective different from scope, lack of information defined as elementary, free availability, among others), it was verified that 17 articles fulfill all the characteristics for the proposed overview. We extracted data on type of HPLC equipment, detectors, wavelength, chromatographic columns, limit of detection, limit of quantification, mobile phase, and time retention. The most commonly used detectors were the tandem mass spectrometric. The limits of detection and quantification were in the unit of measurement of ng?L^?1. With this overview, the importance of high-performance liquid chromatography has been demonstrated to deepen research on estrogen hormone quantification, given the current growth of scientific community concern about the detection of such endocrine disrupters in surface water.