Assessment of cadmium and iron adsorption in sediment,employing a flow injection analysis system with on line filtration and detection by flame atomic absorption spectrometry and thermospray flame furnace atomic absorption spectrometry

This work presents an evaluation of iron and cadmium adsorption in sediment of the Furnas Hydroelectric Plant Reservatory located in Alfenas, Minas Gerais (Brazil). The metal determination was done employing a flow injection analysis (FIA) with an on-line filtering system. As detection techniques, flame atomic absorption spectrometry (FAAS) for iron and thermospray flame furnace atomic absorption spectrometry (TS-FF-AAS) for cadmium determinations were used. The developed methodology presented good limits of detection, being 190 μg L⁻¹ for iron and 1.36 μg L⁻¹ for cadmium, and high sampling frequency for both metals 144 and 60 readings h⁻¹ for iron and cadmium, respectively. Both metals obey the Langmuir model, with maximum adsorptive capacity of 0⋅169 mg g⁻¹ for iron and 7⋅991 mg g⁻¹ for cadmium. For iron, a pseudo-first-order kinetic model was obtained with a theoretical Q_e = 9⋅8355 mg g⁻¹ (experimental Q_e = 9⋅5432 mg  g⁻¹), while for cadmium, a pseudo-second-order kinetic model was obtained, with a theoretical Q_e = 0.3123 mg g⁻¹ (experimental Q_e = 0⋅3052 mg g⁻¹).     

1hJFH coupling in 2‐fluorophenol revisited: Is intramolecular hydrogen bond responsible for this long‐range coupling?

The present study shows that a hydrogen bond between the OH group and the fluorine atom is not involved in the (1h)J(FH) spin-spin coupling transmission either for 4-bromo-2-fluorophenol or 2-fluorophenol. In fact, according to a quantum theory of atoms in molecules analysis, no bond critical point is found between O-H and F moieties. The nature of the transmission mechanism of the Fermi contact term of the (1h)J(FH) spin-spin coupling is studied by analyzing canonical molecular orbitals (see J. Phys. Chem. A 2010, 114, 1044), and it is observed that virtual orbitals play only a quite minor role in its transmission. This is typical of a Fermi contact term transmitted mainly through exchange interactions owing to the overlap of proximate electronic clouds; therefore, it is suggested to identify them as (nTS)J(FH) coupling where n stands for the number of formal bonds separating the coupling nuclei. In the cases studied in this work is n = 4. Results presented in this work could provide an interesting rationalization for different experimental signs known in the current literature for proximate J(FH) couplings.     

Characterizing the dynamics and ligand-specific interactions in the human leukocyte elastase through molecular dynamics simulations

The human leukocyte elastase (HLE), a neutrophil serine protease of the chymotrypsin superfamily, is a major therapeutic target for a number of inflammatory diseases, such as chronic obstructive pulmonary disease (COPD). In this work, we present a comparative explicit water molecular dynamics (MD) study on the free and inhibitor-bound HLE. Knowledge of the flexibility and conformational changes induced by this irreversible inhibitor, whether in a prebound stage or covalently bound at the enzyme binding site, encases fundamental biological interest and is particularly relevant to ongoing structure-based drug design studies. Our results suggest that HLE operates by an induced-fit mechanism with direct intervention of a surface loop which is open toward the solvent in the free enzyme and closed while in the presence of the ligand. MM-PBSA free energy calculations furthermore elucidate the energetic contributions to the distinct conformations adopted by this loop. Additionally, a survey of the major contributions to the inhibitor binding free energies was attained. Our findings enforce the need to account for HLE flexibility, whether through the use of MD-generated ensembles of HLE conformations as targets for molecular docking or via sophisticated flexible-docking algorithms. We anticipate that inclusion of the observed HLE dynamic behavior into future drug design methodologies will have a relevant impact in the development of novel, more efficient, inhibitors.     

Determination of the geographical origin of Brazilian wines by isotope and mineral analysis

In the present research, we studied wines from three different south Brazilian winemaking regions with the purpose of differentiating them by geographical origin of the grapes. Brazil's wide territory and climate diversity allow grape cultivation and winemaking in many regions of different and unique characteristics. The wine grape cultivation for winemaking concentrates in the South Region, mainly in the Serra Gaúcha, the mountain area of the state of Rio Grande do Sul, which is responsible for 90% of the domestic wine production. However, in recent years, two new production regions have developed: the Campanha, the plains to the south and the Serra do Sudeste, the hills to the southeast of the state. Analysis of isotopic ratios of ¹⁸O/¹⁶O of wine water, ¹³C/¹²C of ethanol, and of minerals were used to characterize wines from different regions. The isotope analysis of δ¹⁸O of wine water and minerals Mg and Rb were the most efficient to differentiate the regions. By using isotope and mineral analysis, and discrimination analysis, it was possible to classify the wines from south Brazil.     

A combinatorial proof of Marstrand’s theorem for products of regular Cantor sets

In a paper from 1954 Marstrand proved that if K⊂R² has a Hausdorff dimension greater than 1, then its one-dimensional projection has a positive Lebesgue measure for almost all directions. In this article, we give a combinatorial proof of this theorem when K is the product of regular Cantor sets of class C^1+α, α>0, for which the sum of their Hausdorff dimension is greater than 1.     

Electronic structure of HgBa2Ca(n-1)Cu(n)O(2n+2) (n = 1, 2, 3) superconductor parent compounds from periodic hybrid density functional theory

The electronic structure of HgBa(2)Ca(n) (-1)Cu(n)O(2n+2) (n = 1, 2, and 3) high T(c) superconductor parent compounds has been investigated by means of periodic hybrid density functional theory. Similar to other cuprates, these materials are predicted to exhibit an antiferromagnetic ground state with well localized S = 1/2 magnetic centers at the Cu(2+) sites. However, the presence of the HgO(2) structural units largely defines the nature of states dominating the energy range around Fermi energy. This results in a complex charge transfer character of the insulating gap which decreases when increasing the number of CuO(2) planes in the unit cell, to the point that in the HgBa(2)Ca(2)Cu(3)O(8) compound it becomes so small that one can claim that the resulting material is metallic. Nevertheless, the metallic character arises from the HgO(2) structural units and coexists with the antiferromagnetic order arising from the localized spins at the Cu(2+) sites.     

Yeast cell wall particles: a promising class of nature-inspired microcarriers for multimodal imaging

This communication demonstrates that yeast cell wall particles (YCWPs) are a promising class of nature-inspired biocompatible microcarriers for the delivery of amphipathic/lipophilic imaging reporters. When a paramagnetic MRI agent is loaded, the longitudinal relaxivity per particle at 0.5 T is the highest ever reported for Gd-based systems.     

Classification of Nonnegative g −Harmonic Functions in Half-Spaces

Potential Analysis - In this paper we present a short proof of the following classification Theorem for g ?harmonic functions in half-spaces. Assume that u is a nonnegative solution to...     

Influence of laser repetition rate on ferroelectric properties of pulsed laser deposited BaTiO3 films on platinized silicon substrate

BaTiO₃ thin films were deposited by pulsed laser deposition on Pt–Si at different laser pulse repetition frequencies. X-ray diffraction spectra show that preferred oriented films can be grown by adjusting the pulse repetition frequency. Enhanced dielectric and ferroelectric properties obtained in films deposited at 1 Hz is attributed to preferred orientation, low strain and homogeneous grain distribution. The films deposited at 1 Hz show an impressive remanent polarization of 21.4 μC/cm² with a coercive field of 70.0 kV/cm. The shift in Curie temperature, which stems from changing the laser pulse repetition frequency, is associated with the strain state in the film.     

Stationary phase corrections in the process of bosonization of multi-quark interactions

The functional integration over the auxiliary bosonic variables of cubic order related with the effective action of the Nambu–Jona–Lasinio model with ’t Hooft term has recently been obtained in the form of a loop expansion. Even numbers of loops contribute to the action, while odd numbers of loops are assigned to the measure. We consider the two-loop corrections and analyse their effect on the low-lying pseudoscalar and scalar mass spectra, quark condensates and weak decay constants. The results are compared to the leading order calculations and other approaches. PACS 12.39.Fe, 11.30.Rd, 11.30.Qc