Triboelectric Effect As A New Strategy For Sealing And Controlling The Flow In Paper-based Devices.

We reported here for the first time that triboelectric charges on PET sheets can be used to seal and control the flow rate in paper-based devices. The proposed method exhibits simplicity and low cost, provides reversible sealing and minimizes the effect of sample evaporation.

Assessment Of Robustness On Analysis Using Headspace Solid-phase Microextraction And Comprehensive Two-dimensional Gas Chromatography Through Experimental Designs.

Plackett-Burman experimental design was applied for the robustness assessment of GC×GC-qMS (Comprehensive Two-Dimensional Gas Chromatography with Fast Quadrupolar Mass Spectrometric Detection) in quantitative and qualitative analysis of volatiles compounds from chocolate samples isolated by headspace solid-phase microextraction (HS-SPME). The influence of small changes around the nominal level of six factors deemed as important on peak areas (carrier gas flow rate, modulation period, temperature of ionic source, MS photomultiplier power, injector temperature and interface temperature) and of four factors considered as potentially influential on spectral quality (minimum and maximum limits of the scanned mass ranges, ions source temperature and photomultiplier power). The analytes selected for the study were 2,3,5-trimethylpyrazine, 2-octanone, octanal, 2-pentyl-furan, 2,3,5,6-tetramethylpyrazine, and 2-nonanone e nonanal. The factors pointed out as important on the robustness of the system were photomultiplier power for quantitative analysis and lower limit of mass scanning range for qualitative analysis.

Use Of Experimental Design To Optimize A Triple-potential Waveform To Develop A Method For The Determination Of Streptomycin And Dihydrostreptomycin In Pharmaceutical Veterinary Dosage Forms By Hplc-pad.

An HPLC-PAD method using a gold working electrode and a triple-potential waveform was developed for the simultaneous determination of streptomycin and dihydrostreptomycin in veterinary drugs. Glucose was used as the internal standard, and the triple-potential waveform was optimized using a factorial and a central composite design. The optimum potentials were as follows: amperometric detection, E1=-0.15V; cleaning potential, E2=+0.85V; and reactivation of the electrode surface, E3=-0.65V. For the separation of the aminoglycosides and the internal standard of glucose, a CarboPac™ PA1 anion exchange column was used together with a mobile phase consisting of a 0.070 mol L(-1) sodium hydroxide solution in the isocratic elution mode with a flow rate of 0.8 mL min(-1). The method was validated and applied to the determination of streptomycin and dihydrostreptomycin in veterinary formulations (injection, suspension and ointment) without any previous sample pretreatment, except for the ointments, for which a liquid-liquid extraction was required before HPLC-PAD analysis. The method showed adequate selectivity, with an accuracy of 98-107% and a precision of less than 3.9%.

Desenvolvimento e avaliação de uma servoválvula de baixo custo para a aplicação de insumos líquidos

The present work aimed the development of a low cost servo-valve that answers to an electronic control signal, for variable rates liquid inputs application. A literature research to define which valve type should be used was made. A mechanically activated proportional valve with an electronically controlled servo-engine was designed and evaluated. Since developed the servo-valve, the system was submited to a number of tests .The evaluation of its behavior was obtained in terms of repeatability, hystheresis and linearity. The test was accomplished in a bench, specially developed for this aim. As a result, were obtained three curves of opening percentage as function of flow rate, describing three opening and closing increments in two different work pressures. The servo-valve presented a good repeatability, reasonable hysteresis and a typically quadratic curve. This one maintained the low cost target. These results were very satisfied because the non-linearity and the hysteresis could be easily corrected by software.

Proposta de mecanismo de lavagem em equipamentos de beneficiamento de tomate de mesa

The cleanness level in fresh market tomatoes cleaning equipment is essential for consumer acceptance and conservation of product quality. However, the washing process in cleaning current equipments demands an excessive volume of water, leading to serious economic and environmental concerns. The objective of this work was to contribute with technical information for the washing system optimization. The conventional washing system currently used in cleaning equipment, which consists of perforated PVC pipes, was compared with a proposed system which uses commercial sprays. Characteristic curves (flow rate versus pressure) for both systems were determined in lab conditions and the respective water consumptions were compared. The results confirmed the excess of water consumption in the conventional washing systems, and the proposed system proved that is possible to reduce it, and the use of sprays allowed the rational use of the water.

Eficiência do processo de recobrimento de sementes de brócolos recobertas com polímero em leito de jorro

Broccoli seeds were coated in a conical-cylindrical spouted bed with an aqueous suspension of hydroxy ethyl cellulose aiming to improve the seeds coating technique using a fluid-dynamic process. An experimental design was applied to investigate the effects of the operating variables: gas temperature, atomizing air pressure and suspension flow rate on the germination of the seeds and on the process efficiency. Results indicated that the operating variables affect both the coating process efficiency and the germination ability. However, the analysis didn t identify differences between the germination potential of coated and uncoated seeds. Coated seeds absorbed up to 10 percent less moisture than the uncoated ones, when the environment temperature and humidity were controlled over a period of time.

Fluidodinâmica de sementes de brócolos em leito fluizado e leito de jorro

The spouted and fluidized bed technologies are usually employed in operations of drying, coating and granulation of particles by the chemical and pharmaceutical industries. The use of these techniques in agronomy is limited to the treatment of some species of seeds. In this work, the objective was to analyse the fluid-dynamics of fluidized and spouted beds when broccoli (Brassica oleracea L. var. Italica) seeds are used and also to verify the influence on seed germination after 60 min of seed exposition to spouting or fluidization, at room temperature. The fluid-dynamics was defined by the measurements of the bed pressure drop as a function of the air flow rate for different seeds loads. The experimental conditions were based on the physical properties of the seeds and were limited by the apparatus dimensions. The cone-cylindrical bed was constructed in plexyglass to permit flow visualization. The values of the parameters: maximum pressure drop, minimum spouting flow rate and pressure drop, and stable spout pressure drop were experimentally obtained from the fluid-dynamic analysis and were compared with the values calculated by empirical equations found in the literature. The same procedure was carried out with the fluidized bed and the important parameters for this regime were the air velocity and the bed pressure drop at minimum fluidization. The analysis of seed germination indicated that no damage was caused to the seeds by the spout or fluidization processes.

PREDIÇÃO DA ATIVIDADE DE ÁGUA E RELAÇÃO ENTRE A ATIVIDADE DE ÁGUA E A DEPRESSÃO DO PONTO DE CONGELAMENTO DE SUCOS DE FRUTAS

This work proposes to determine the water activity and the freezing point depression of tangerine, pineapple and lemon juices at various concentrations (10-55oBrix) and to achieve a correlation between these properties. The freezing point depression was determined with a LAKTRON cryoscope and common laboratory materials. The water activity was determined with a DECAGON CX-2 hygrometer in the temperature range of 15 to 30oC. With the results, the adjustment to CHEN (1987) water activity prediction equation to non-electrolyte mixtures was verified, through the calculation of the variation coefficient (CV). Being CV smaller than 3% for the proposed model, it can be said that the experimental data have adjusted well to the prediction equation. The water activity and the freezing point depression was correlated for tangerine, pineapple and lemon juices and r2 values were higher than 99%. Therefore, it is possible to obtain the water activity by knowing the freezing point depression of studied juices.

Estudo da frequencia cardiaca de atletas de handebol segundo situação de jogo, durante 3 partidas oficiais dos 42º Jogos Regionais da Zona Leste do Estado de São Paulo

Universidade Estadual de Campinas . Faculdade de Educação Física