Effect of process variables on the osmotic dehydration of star-fruit slices

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)The objective of this work was to study the effect of blanching and the influence of temperature, solution concentration, and the initial fruit:solution ratio on the osmotic dehydration of star-fruit slices. For blanching, different concentrations of citric and ascorbic acids were studied. The samples immersed in 0.75% citric acid presented little variation in color in relation to the fresh star-fruit. Osmotic dehydration was carried out in an incubator with orbital shaking, controlled temperature, and constant shaking at 120 rpm. The influence of process variables was studied in trials defined by a complete 2(3) central composite design. In general, water loss and solids gain were positively influenced by temperature and by solution concentration. Nevertheless, lower temperatures reduced water loss throughout the osmotic dehydration process. An increase in the amount of dehydrating solution (initial fruit:solution ratio) slightly influenced the evaluated responses. The process carried out at 50 degrees C with a solution concentration of 50% resulted in a product with lower solids gain and greater water loss. Under these conditions, blanching minimized the effect of the osmotic treatment on star-fruit browning, and therefore the blanched fruits showed little variation in color in relation to the fresh fruit.322357365SAE (Servico de Apoio ao Estudante - UNICAMP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP

The study of atmospheric ice-nucleating particles via microfluidically generated droplets

Ice-nucleating particles (INPs) play a significant role in the climate and hydrological cycle by triggering ice formation in supercooled clouds, thereby causing precipitation and affecting cloud lifetimes and their radiative properties. However, despite their importance, INP often comprise only 1 in 10³–10⁶ ambient particles, making it difficult to ascertain and predict their type, source, and concentration. The typical techniques for quantifying INP concentrations tend to be highly labour-intensive, suffer from poor time resolution, or are limited in sensitivity to low concentrations. Here, we present the application of microfluidic devices to the study of atmospheric INPs via the simple and rapid production of monodisperse droplets and their subsequent freezing on a cold stage. This device offers the potential for the testing of INP concentrations in aqueous samples with high sensitivity and high counting statistics. Various INPs were tested for validation of the platform, including mineral dust and biological species, with results compared to literature values. We also describe a methodology for sampling atmospheric aerosol in a manner that minimises sampling biases and which is compatible with the microfluidic device. We present results for INP concentrations in air sampled during two field campaigns: (1) from a rural location in the UK and (2) during the UK’s annual Bonfire Night festival. These initial results will provide a route for deployment of the microfluidic platform for the study and quantification of INPs in upcoming field campaigns around the globe, while providing a benchmark for future lab-on-a-chip-based INP studies

Comparative analysis of thin Ni and CoNiMnP magnetic films

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)The results of an investigation of thin Ni and CoNiMnP films deposited by electroplating over polyurethane-acrylate flexible substrates are presented. To improve magnetic properties of the films, an electroplating process was carried out with assistance of a strong magnetic field (3900 G). The evaluated film properties were coercivity, remanence, maximum energy product, adherence and film composition. Comparison between the magnetic properties of the samples has shown that Ni and CoNiMnP films are suitable for distinct areas of applications in micro-devices: vibrating diaphragms and micro-magnet machines, respectively. (c) 2012 Elsevier B.V. All rights reserved.5201548714874Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)INCT NAMITECFundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq

Electric field driven addressing of ATPS droplets in microfluidic chips

Referujeme o možnosti ovlivňovat pohyb kapek (adresování kapek) pomocí stejnosměrného elektrického pole v systému dvoufázového vodného roztoku (ATPS). Byly zkoumány tři systémy ATPS typu polyetylenglykol/sůl, jmenovitě polyetylenglykol/fosfát, polyetylenglykol/síran a polyetylenglykol/uhličitan. Série pokusů s adresováním a slučováním kapek v mikrofluidním čipu ukázaly, že stejnosměrné elektrické pole může být užitečným nástrojem pro chytrou manipulaci kapek v systémech polyetylenglykol/sůl.The possibility of controlled droplet motion (droplet addressing) mediated by DC electric field in aqueous two-phase systems (ATPS) is here reported for the first time. Three ATPS of polyethylene glycol (PEG)/salt type, namely PEG/phosphate, EG/sulphate, and PEG/carbonate, were selected for this study. We observed fast motion of salty droplets dispersed in PEG continuous phase induced by electric field of relative low strength. Hence, three fluidic systems with separated electrode chambers for the evaluation of electrophoretic mobilities and for addressing experiments were fabricated. Electrophoretic mobilities of salty droplets always exceeded the value of 1 × 10−7 m2V−1s−1, which is about by one magnitude higher value than those typically measured in water–oil droplet systems. The electrophoretic mobilities in systems with free surface are the same or even smaller than in closed microfluidic structures, which is accounted mainly to the fact that a significant part of salty droplets is exposed to air and does not contribute to droplet forcing. Series of addressing and merging experiments in a microfluidic chip shows that DC electric field can be used as a powerful tool for smart manipulation of droplets in microfluidic systems with PEG/salt ATPS