Electrochemical behavior of parent and photodegradation products of some selected pesticides

Electrochemical behavior of pesticides is extensively studied, but little attention has been given to the study of their degradation products (by-products) by electrochemical methods. However, the degradation products of pesticides can be even more toxic then the parent products and such studies should be encouraged. Therefore, the objective of this work was to evaluate the electroactivity of by-products of imazaquin, methylparathion, bentazon and atrazine, generated by UV irradiation and measured using cyclic and differential pulse voltammetry and UV-visible absorption spectrophotometry. Results have shown that several by-products exhibit electroactivity, allowing, in some cases, the simultaneous determination of both parent and degradation products.EMBRAPACoordenacao de Aperfeicoamento de Pessoal de Nivel Superior (CAPES)CNPqFAPES

Physical and morphological characterization of reactively magnetron sputtered TiN films

The present paper reports the influence of growth conditions on the properties of TiN thin films deposited by rf reactive magnetron sputtering in the low-pressure range. The effects of rf power at the Ti target and the negative bias voltage at the substrate in the morphology, structure, electrical resistivity and colour of the samples were studied in detail. X-Ray diffraction results showed that the delta-TiN phase (a(0) similar to 0.430 nm) is detected in all the samples. The sample prepared with grounded substrate revealed a lattice parameter close to the bulk value (0.424 nm), which is a consequence of a low stress state, due to the absence of ion bombardment. The sample deposited at 1000 W has a lattice parameter of 0.426 nm, close to that of the stress-free material (a(0) =0.424 nm), probably due to some stress relief. All films have a columnar-type structure, lying in the T and I zone of the Thornton Model. The resistivity of the TiN films is almost constant and close to 60 muOmega cm independently of the preparation conditions, except for the films deposited at 1000 W, p similar to 215 muOmega cm, and for the grounded sample, p similar to 153 muOmega cm. These values are probably due to cracks associated with stress relieves, in the first case, and the lack of ion bombardment that leads to films with lower density and higher number of defects in the second. No significant variations in colour were observed

Energy production from lipids by novel anaerobes

[Excerpt] Anaerobic microbial diversity encloses a very high potential that can be used for biotechnological applications. This potential is still largely unexplored, since the majority of the microorganisms in Nature are unknown or poorly characterized. This work is focused on the study of novel anaerobic microorganisms that participate in the metabolism of lipids, long chain fatty acids (LCFA) and glycerol, with the main goal of producing valuable energy-rich organic compounds. For that, conventional anaerobic culturing procedures were combined with continuous bioreactors operation and allied to microbial ecology approaches. Two main examples of the work performed will be presented. (...

Electroanalytical method for the analysis of methyldopa in pharmaceutical tablets using a crude extract of laccase from Pycnoporus sanguineus as oxidizing agent

Several colorimetric and chromatographic methods have been used for the identification and quantification of methyldopa (MA) in pharmaceutical formulations and clinical samples. However, these methods are time- and reagent-consuming, which stimulated our efforts to develop a simple, fast, and lowcost alternative method. We carried out an electroanalytical method for the determination of MA in pharmaceutical formulations using the crude enzymatic extract of laccase from Pycnoporus sanguineus as oxidizing agent. This method is based on the biochemical oxidation of MA by laccase (LAC), both in solution, followed by electrochemical reduction on glassy carbon electrode surface. This method was employed for the determination of MA in pure and pharmaceutical formulations and compared with the results obtained using the official method. A wide linear curve from 2.5 x 10-5 to 1 x 10-4 mol L-1 was found with a detection limit calculated from 4.5 x 10-6 mol L-1.Colegio de Farmacéuticos de la Provincia de Buenos Aire

Molecular Characterization of the Schistosoma mansoni Zinc Finger Protein SmZF1 as a Transcription Factor

Schistosomes are parasites that exhibit a complex life cycle during which they progress through many morphological and physiological transformations. These transformations are likely accompanied by alterations in gene expression, making genetic regulation important for parasite development. Here we describe a Schistosoma mansoni protein (SmZF1) that may act as a parasite transcription factor. These factors are key proteins for gene regulation. We have previously demonstrated that SmZF1 is able to bind DNA and that its mRNA is present at different stages during the parasite life cycle. In this study we aimed to define if this protein can function as a transcription factor in S. mansoni. SmZF1 was detected in the nucleus of adult male worms, cercariae and schistosomula cells. It was not, however, observed in female cells, suggesting it to be gender specific. We used mammalian cells expressing recombinant SmZF1 to analyze if SmZF1 protein is able to activate/repress gene transcription and demonstrated that it increased the expression of a reporter gene by two-fold. The results obtained confirm SmZF1 as a S. mansoni transcription factor

Potential biological properties of lycopene in a self-emulsifying drug delivery system

In recent years, lycopene has been highlighted due to its antioxidant and anti-inflammatory properties, associated with a beneficial effect on human health. The aim of this study was to advance the studies of antioxidant and anti-inflammatory mechanisms on human keratinocytes cells (HaCaT) of a self-emulsifying drug delivery system (SEDDS) loaded with lycopene purified from red guava (nanoLPG). The characteristics of nanoLPG were a hydrodynamic diameter of 205 nm, a polydispersity index of 0.21 and a zeta potential of −20.57, providing physical stability for the nanosystem. NanoLPG demonstrated antioxidant capacity, as shown using the ORAC methodology, and prevented DNA degradation (DNA agarose). Proinflammatory activity was evaluated by quantifying the cytokines TNF-α, IL-6 and IL-8, with only IL-8 showing a significant increase (p < 0.0001). NanoLPG showed greater inhibition of the tyrosinase and elastase enzymes, involved in the skin aging process, compared to purified lycopene (LPG). In vitro treatment for 24 h with 5.0 µg/mL of nanoLPG did not affect the viability of HaCaT cells. The ultrastructure of HaCaT cells demonstrated the maintenance of morphology. This contrasts with endoplasmic reticulum stresses and autophagic vacuoles when treated with LPG after stimulation or not with LPS. Therefore, the use of lycopene in a nanoemulsion may be beneficial in strategies and products associated with skin health.info:eu-repo/semantics/publishedVersio

Attractor dynamics approach to joint transportation by autonomous robots: theory, implementation and validation on the factory floor

This paper shows how non-linear attractor dynamics can be used to control teams of two autonomous mobile robots that coordinate their motion in order to transport large payloads in unknown environments, which might change over time and may include narrow passages, corners and sharp U-turns. Each robot generates its collision-free motion online as the sensed information changes. The control architecture for each robot is formalized as a non-linear dynamical system, where by design attractor states, i.e. asymptotically stable states, dominate and evolve over time. Implementation details are provided, and it is further shown that odometry or calibration errors are of no significance. Results demonstrate flexible and stable behavior in different circumstances: when the payload is of different sizes; when the layout of the environment changes from one run to another; when the environment is dynamice.g. following moving targets and avoiding moving obstacles; and when abrupt disturbances challenge team behavior during the execution of the joint transportation task.- This work was supported by FCT-Fundacao para a Ciencia e Tecnologia within the scope of the Project PEst-UID/CEC/00319/2013 and by the Ph.D. Grants SFRH/BD/38885/2007 and SFRH/BPD/71874/2010, as well as funding from FP6-IST2 EU-IP Project JAST (Proj. Nr. 003747). We would like to thank the anonymous reviewers, whose comments have contributed to improve the paper