Jurandir Pereira Pinto

Antimicrobial activity of essential oils from Pimenta pseudocaryophyllus and Tynanthus micranthus

The present study describes the chemical composition and antimicrobial activity of essential oils obtained by hydrodistillation from the leaves of Pimenta pseudocaryophyllus (1.0% w/w) and Tynanthus micranthus (1.1% w/w). GC and GC/MS analysis demonstrated that eugenol was the only component in the T. micranthus essential oil (99.9%) and the major component in the P. pseudocaryophyllus essential oil (92.59%), which also presented methyleugenol, terpinen-4-ol, o-cymene and (E)-caryophyllene, among others. Both the oils presented antimicrobial activity against bacteria, yeast and filamentous fungi tested.The Bioautography test revealed that eugenol was the bioactive component in both the oils against Cladosporium herbarum. This is the first report about the T. micranthus essential oil, and the antifungal activity of P. pseudocaryophyllus. The results confirmed the potential of eugenol-rich essential oils not only as a source of flavor compounds, but also of use as antimicrobial agent in agriculture and in pharmaceutical and food products.

Dead-time compensation in Shunt Active Power Filters using fast feedback loop

In PWM inverters, a time delay between consecutive semiconductor switching is introduced to prevent a short circuit in the DC link. This action causes the dead-time effect, which is detrimental to the performance of inverters. This paper deals with a new technique that speedup the feedback loop in Shunt Active Power Filter, in order to compensate the dead-time effect. A simple method based on an average value theory can be used to compensate this effect. For Shunt Active Power Filters (SAPF), the compensation can be done in two different ways, one for the feedforward configuration and the other for the feedback one. This paper presents both techniques and discusses the details, advantage of the feedback implementation with a new fast feedback loop that guaranties the dead-time compensation and the overall stability. Experimental results are presented showing the effectiveness of the proposed technique.

Study of oxidation kinetics of b100 biodiesel from soybean and pig fat: activation energy determination.

The quality of biodiesel is extremely important for its commercialization and use; oxidation of biodiesel is a critical factor because it decreases the fuel storage time. A commercial biodiesel was mixed with synthetic antioxidants, according to a simplex-centroid experimental mixture design, and its stability was evaluated through induction period and activation energy. In all trials, addition of antioxidants increased activation energy in the mixtures containing tertiary butylhydroquinone (TBHQ). When a mixture containing 50% TBHQ and 50% butylated hydroxyanisole was used, synergistic effect was observed, and the major activation energy obtained was 104.43 kJ mol-1.

Phytochemical and antifungal activity of anthraquinones and root and leaf extracts of Coccoloba mollis on phytopathogens

The aim of this work was to study the phytochemical and antifungal activity of anthraquinones and root and leaf extracts of Coccoloba mollis on phytopathogens. The chemical analysis of ethanolic extracts showed a mixture of long-chain hydrocarbons, carboxyl esters and 3-taraxerone in the leaf extract. Two anthraquinones (emodin and physcion) were isolated and identified from the root extract. Phytochemical screening using the pharmacognostic methods revealed the presence of flavonoids and tannins in the leaves and roots. Anthraquinones were only found in the root extract, no alkaloids, coumarins, saponins and simple phenolics were present. The antifungal activity of C. mollis extracts and anthraquinones isolated from the root of this plant against Botryospheria ribis, B. rhodina, Lasiodiplodia theobromae and Fusarium sp showed promising results for their use as fungicides, where emodin was the most active compound, which inhibited the microorganisms tested up to 44%.

Comparison of rural and urban atmospheric aldehydes in Londrina, Brazil

Ambiental levels of formaldehyde and acetaldehyde were measured at three sites in the city of Londrina: at the central bus station, downtown (night and day profiles) and in a rural area, during the summer and winter seasons of 2002. Atmospheric aldehydes were collected using C18 Sep-Pak cartridges coated with 2,4-DNPH and analyzed by HPLC-DAD. At the central bus station, the measured mixing atios for formaldehyde and acetaldehyde ranged, respectively, from 6.17 to 10.43 ppbv and from 0.49 to 2.12 ppbv. Downtown, during the summer, formaldehyde levels ranged from 2.07 to 5.65 ppbv, and acetaldehyde levels ranged from 1.05 to 5.06 ppbv. During the winter, the daytime concentrations for formaldehyde and acetaldehyde were higher than nighttime levels. Formaldehyde and acetaldehyde mixing ratios ranged from 3.24 to 9.46 ppbv and from 2.81 to 10.83 ppbv, respectively. At the rural site, formaldehyde and acetaldehyde mixing ratios ranged from 0.64 to 1.41 ppbv and from 0.10 to 0.87 ppbv, respectively. The acetaldehyde/formaldehyde ratios were compared with values from other Brazilian cities.

Modified Synchronous Reference Frame strategy for single phase hybrid active power filter

This paper evaluates a hybrid active series power filter (HASPF) based on the Modified Synchronous Reference Frame, when the third harmonic passive filter is the chosen compensator at first. The performance of the system is compared with and without the active compensation. The practical results exhibits as close a passive filter can be tuned to an absolutely compensation. The algorithm of the HASPF is executed by the DSP TMS320F2812, and the inverter switching frequency is 20 kHz.

Artificial neural networks in the classification and identification of soybean cultivars by planting region

Vinte variedades de soja (Glycine max), quatorze convencionais e seis variedades transgenicas (RR) foram analisadas quanto ao teor de proteina, acido fitico, teor de oleo, fitosterois, cinzas, minerais e acidos graxos que foram tabelados e apresentados a rede neural do tipo perceptron de multiplas camadas para a classificacao e identificacao quanto a regiao de plantio e quanto a variedade convencional ou transgenica. A rede neural utilizada classificou e testou corretamente 100% das amostras cultivadas por regiao. Para o banco de dados contendo informacoes sobre sojas transgenicas e convencionais foi obtido um desempenho de 94,43% no treinamento da rede, 83,30% no teste e 100% na validacao.

Carbonyl concentrations from sites affected by emission from different fuels and vehicles

Concentrations of carbonyl compounds were evaluated on places impacted by emissions from different fuels and vehicles. In order to evaluate the concentrations, four campaigns during the winter and summer of 2011 and 2012 were performed, inside a covered parking area in a commercial establishment where mainly gasohol and ethanol vehicles are in circulation. Also, measurements were done inside a semi–closed bus station, which is the direct source of emissions from heavy duty vehicles (i.e. buses) burning B3–diesel (3% biodiesel and 97% diesel). The results indicated that acetaldehyde is the main aldehyde emitted by light vehicles due to large use of ethanol in Brazil by these vehicles. In addition, the concentrations found in the bus station revealed that B3–diesel fuel increases the emissions of carbonyl compounds and that of acetaldehyde when compared with results from B0–diesel at same bus station. Possible impacts of changing diesel to B3–diesel indicate an increase of ozone formation. In terms of health, a lower impact was estimated considering only the changes in formaldehyde concentrations.

Simplified Space Vector PWM Algorithm for Multilevel Inverters Using Non-Orthogonal Moving Reference Frame

This work proposes a simplified space vector PWM algorithm for multilevel inverters using non-orthogonal moving reference frame. In this strategy, the non-orthogonal reference frame rotates accordingly with the sector where the reference vector lies. The nearest three vectors (NTV) are determined via identification of the triangle in hexagon, using information about the sector and the triangle where the reference vector lies. The duty-cycles are determined using a single calculation equation set. Therefore, the logic tests used by formerly proposed algorithms to determine the NTV and to calculate the duty-cycles are no longer necessary. The calculation of triangle location and duty-cycle considering the NTV are simple. The switching pattern is generated via the selection of coefficients stored in look-up table. The approach works for any number of levels, and its great advantage is that the complexity of the algorithm no longer increases, close to cubically, with the number of the inverter levels. Simulation and experimental results shows the algorithm feasibility.

Evaluation of the Auto-Associative Neural Network Based Sensor Compensation in Drive Systems

The paper performs a deep analysis of the sensor drift compensation in motor drives approach presented in past publications [11-12]. In the past, the auto-associative neural networks (AANN) were found to be effective for this application. However, it is still unclear how much improvement may be obtained compared with other modeling techniques and when it is adequate to be applied. Therefore, the modeling techniques, specially the AANN, are detailed and evaluated using performance metrics. Additional experimental results in a motor drive are provided to show the compensation capability of the AANN. The feedback signals are given as the AANN inputs. The AANN then performs the auto-associative mapping of these signals so that its outputs are estimations of the sensed signals. Since the AANN exploits the physical and analytical redundancy, whenever a sensor starts to drift, the drift is compensated, and the performance of the drive system is barely affected.