Filtros digitais por transformadas de Fourier aplicados em eletroquímica

The electrochemical properties of micro and nano-electrodes are widely investigated due to their low faradaic and capacitive currents, leading to a new generation of smart and implantable devices. However, the current signals obtained in low-dimensional devices are strongly influenced by noise sources. In this paper, we show the evaluation of filters based on Fast Fourier Transform (FFT) and their implementation in a graphical user interface (GUI) in MATLAB®. As a case study, we evaluated an electrochemical reaction process of charge transfer via outer-sphere. Results showed successful removal of most of the noise in signals, thus proving a promising tool for low-scale measurement.

Sonication-assisted preparation of CaO nanoparticles for antibacterial agents

The effect of calcination conditions on the size and killing activity of CaO nanoparticles towards L. plantarum was studied in this paper. The results showed that CaO nanoparticles with a diameter of 20 nm could be obtained under the investigated conditions. The lethal effect of CaO nanoparticles after incubation of 6 or 24 h increased with increasing calcination time. Using CaO-SA, CaO-SB, and CaO-SC after a 24-h exposure, 2.25, 3.37, and 5.97 log L. plantarum were killed, respectively, at a concentration of 100 ppm. The current results show that the use of CaO nanoparticles as antibacterial agents has significant potential in food-relevant industries.

Bionanocompósitos preparados por incorporação de nanocristais de celulose em polímeros biodegradáveis por meio de evaporação de solvente, automontagem ou eletrofiação

This review reports the preparation and characterization of bionanocomposites based on biodegradable polymers reinforced with cellulose nanocrystals (CNC) described in the literature. The outstanding potential of cellulose nanocrystals as reinforcement fillers of biodegradable polymers is presented with an emphasis on the solution casting process, which is an appropriate method to investigate the physico-chemical effects of the incorporation of CNC into the polymeric matrices. Besides solution casting, other small scale methods such as electrospinning and layer-by-layer are also covered.

CONSTRUÇÃO DE UM DISPOSITIVO DE PRESSURIZAÇÃO A VÁCUO PARA A PREPARAÇÃO DE FASES ESTACIONÁRIAS MONOLÍTICAS VIA PROCESSO SOL-GEL

The filling of capillaries via the sol-gel process is growing. Therefore, this technical note focuses on disseminating knowledge acquired in the Group of Analytical Chemistry and Chemometrics over seven years working with monolithic stationary phase preparation in fused silica capillaries. We believe that the detailed information presented in this technical note concerning the construction of an alternative high pressurization device, used to fill capillary columns via the sol-gel process, which has promising potential for applications involving capillary electrochromatography and liquid chromatography in nano scale, may be enlightening and motivating for groups interested in developing research activities within this theme.

Potential applications of nanotechnology in the agro-food sector

Nanoscience and nanotechnology are new frontiers of this century. Their application to the agriculture and food sectors is relatively recent compared with their use in drug delivery and pharmaceuticals. Smart delivery of nutrients, bioseparation of proteins, rapid sampling of biological and chemical contaminants, and nanoencapsulation of nutraceuticals are some of the emerging topics of nanotechnology for food and agriculture. In this review, some applications of nanotechnology in agro-food sector are discussed.

Application of fats in some food products

Fats and oils are very important raw materials and functional ingredients for several food products such as confectionery, bakery, ice creams, emulsions, and sauces, shortenings, margarines, and other specially tailored products. Formulated products are made with just about every part of chemistry, but they are not simple chemicals. In general, they consist of several, and often many, components. Each of these components has a purpose. Most formulated products have a micro- or nano-structure that is important for their function, but obtaining this structure is often the big challenge. Due to a rise in overweight or obesity, health concerns have increased. This fact has led to the need to the develop products with low fat content, which have become a market trend. In addition, the development of new products using fat substitutes can be a good option for companies that are always trying to reduce costs or substitute trans fat or saturated fat. However, the successful development of these products is still a challenge because fat plays multiple roles in determining the desirable physicochemical and sensory attributes, and because the consumers who want or need to replace these ingredients, seek products with similar characteristics to those of the original product. Important attributes such as smooth, creamy and rich texture; milky and creamy appearance; desirable flavor; and satiating effects are influenced by the droplets of fat, and these characteristics are paramount to the consumer and consequently crucial to the success of the product in the market. Therefore, it is important to identify commercially viable strategies that are capable of removing or reducing fat content of food products without altering their sensory and nutritional characteristics. This paper intended to provide an overview about the role of fat in different food systems such as chocolate, ice cream, bakery products like biscuits, breads, and cakes considering the major trends of the food industry to meet the demands of modern society.