Trace elements status in the terrain of an impounded vehicle scrapyard

Journal of Radioanalytical and Nuclear Chemistry - The impact of a scrapyard of impounded vehicles in São Paulo state on topsoil was evaluated for As, Ba, Co, Cr, Cu, Mo, Ni, Pb, V, Zn and...     

Macrocyclic ZnII and CuII complexes as guests of the hybrid composites based on the layered MnPS3 phase. Comparison of spectroscopic properties

A family of macrocyclic complexes [M₂LⁿCl₂] have been synthesized and characterized (M: Cu^II or Zn^II; Lⁿ: macrocyclic ligand derived from 2-hydroxy-5-methyl-1,3-benzenedicarbaldehyde and different aliphatic diamines and o-phenylenediamine). The influence of the aromaticity of the ligand and the metal center on the spectroscopic properties of the complexes (absorption and emission) has been studied. Making use of the weak interactions between hydrated potassium ions and the layers of the K_0.4Mn_0.8PS₃ precursor, the obtained macrocyclic complexes have been intercalated in the interlamellar space by a microwave assisted cationic exchange reaction. The optical properties of the obtained hybrid materials are reported. The absorption edge, recorded by solid state reflectance spectroscopy for Cu^II and the Zn^II macrocycle-based composites, is 1.67–1.76 eV, both shifted to lower energy compared with that of the pristine MnPS₃.     

The mobility in disordered molecular systems with energies given by a charge-induced dipoles interaction

We investigate the field dependence of the mobility in a model for a disordered molecular system containing spatial and energetic disorders. In this model we assign an isotropic polarizability to each site and take the site energies to be the site polarization energies, the interaction energy of a charge in the given site with the induced dipoles in the neighboring sites. This model was shown, in a previous publication, to contain short-ranged energetic correlations and we show in this work that this correlation produces a charge mobility proportional to the exponential of the square root of the applied field, the Poole-Frenkel dependence observed in various disordered organic materials, over a significant range of fields. We present an expression for the field dependence of the mobility in terms of the average intersite separation and of the isotropic polarizability of the electronic states, the two model parameters.     

Lipoxygenase inhibitory activity of Cuspidaria pulchra and isolated compounds

This work evaluated the in vitro inhibitory activity of the crude ethanolic extract from the aerial parts of Cuspidaria pulchra (Cham.) L.G. Lohmann against 15-lipoxygenase (15-LOX). The bioassay-guided fractionation of the n-butanol fraction, which displayed the highest activity, led to the isolation of three compounds: caffeoylcalleryanin (1), verbascoside (2) and 6-hydroxyluteolin-7-O-β-glucoside (3). Assessment of the ability of the isolated compounds to inhibit 15-LOX revealed that compounds 1, 2 and 3 exerted strong 15-LOX inhibitory activity; IC₅₀ values were 1.59, 1.76 and 2.35 μM respectively. The XTT assay showed that none of the isolated compounds seemed to be significantly toxic.     

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).     

Evaluations of the BET, I-point, and α-plot procedures for the routine determination of external specific surface areas of highly dispersed and porous silicas

Nitrogen adsorption isotherms of silicas and other oxidic materials are distorted by the presence of micropore adsorption and capillary condensation. This distortion affects the determination of the specific area of the material, depending on the chosen calculation procedure. Correction of the initial (total) isotherm for micropore capacity decreases or eliminates this source of error to give a useful estimate of the external surface area. In the present work, 26 silica-based adsorbent materials were studied to obtain total and external specific surface areas by the Brunauer-Emmett-Teller (BET), I-point, and α-plot procedures, using the micropore capacities from the α-plots to obtain the corrected (external) isotherms. Errors in the specific surface areas due to the presence of micropores are given by the equation ΔsA = 3.267 (m(2)/cm(3) STP) sV(mic), where sA is the specific surface area in m(2)/g and sV(mic) is the micropore capacity in cm(3) STP/g. A consistent set of conversion factors was obtained by which the external specific surface area obtained using one of these procedures can be converted, with part-per-thousand precision, to either of the others. Although the I-point procedure presents the advantage of not requiring a defined p/p(0) range, the α-plot procedure is recommended for routine determinations of external specific areas of silicas and other oxidic materials, except for cases in which the shapes of the adsorption isotherms of the sample and the reference differ significantly from one another in the p/p(0) range used for the determination.     

Comparative properties of Amazonian oils obtained by different extraction methods

Pequi (Caryocar brasiliense Camb.), baba?u (Orbignya phalerata Mart.), buriti (Mauritia flexuosa), and passion fruit (Passiflora edulis) oils were studied to determine their antibacterial, antioxidant and cytotoxic activities, as well as their total phenol and carotenoid contents. The fatty acid contents were determined by GC-MS. The three types of passion fruit oils studied were refined, cold pressed or extracted from seeds in a Soxhlet apparatus. The oils thus obtained showed differences in antioxidant activity and carotenoid content, but were similar in regard to total phenols. Buriti and pequi had the highest carotenoid contents, while refined and cold pressed passion fruit oil displayed the highest antioxidant activity. Pequi oil was the only oil to display antibacterial and cytotoxic activity.     

Study of ProtoPorphyrin IX Elimination by Body Excreta: A new Noninvasive Cancer Diagnostic Method?

This paper describes the elimination of porphyrins by feces. It was demonstrated that porphyrin accumulates substantially more in tumors than in normal tissues, and consequently more PPIX reaches the blood of patients and animals with tumors, and then, it needs to be eliminated. The fluorescence of feces revealed that there are large amounts of PPIX in the excreta of animals with cancer comparing with healthy animals. The autofluorescence of feces porphyrin extracted with acetone was analyzed using fluorescence spectroscopy of animals inoculated with DU145 cells into the prostate and healthy animals to monitor the PPIX concentration. Emission spectra were obtained by exciting the samples at 405 nm. Significant differences were observed in autofluorescence intensities measured in the 575–725 nm spectral regions for the studied groups. The results showed a noninvasive, simple, rapid and sensitive method to detect cancer by feces analysis.