A Rapid and Eco-Friendly Method for Determination of Hydrolysable Tannins and Its Application to Honey Samples

This paper describes the development of a rapid and clean method for the determination of hydrolysable tannins in honey samples, focusing on an easy and green sample pretreatment and low generation of waste. The proposed method is based on the reaction between KIO₃ and hydrolysable tannin compounds in acetate buffer medium (pH 4.75), with formation of a colored product measured at 525 nm. The analytical conditions were optimized using experimental design (central composite design). The linear range obtained was 40.0–740 mg L^?1 (r?=?0.998), and the detection (LOD) and quantification (LOQ) limits were 12.2 and 40.8 mg L^?1, respectively. Acetate buffer was used to ensure formation of the colored product obtained by reaction between the chromogenic reagent and the analyte. The method showed good results when applied to honey samples, with recoveries in the range of 78.3–96.1 %, and the use of diffuse reflectance spectroscopy coupled with spot test analysis provided low reagent consumption and minimized waste generation. The results obtained with the proposed method were confirmed by a spectrophotometric method.     

Influence of CTAB on the electrochemical behavior of dopamine and on its analytic determination in the presence of ascorbic acid

This research work concerns the electrochemical study of dopamine and ascorbic acid in the presence of the cationic surfactant cetyltrimethylammonium bromide. From this study is possible to note that the cetyltrimethylammonium bromide greatest influence was on the dopamine, because it disfavors both its oxidation and reduction, thereby giving a smaller heterogeneous rate constant, k ⁰, value than in its absence, provoking that the process tends to irreversibility. On the contrary, for the ascorbic acid case, its oxidation was favored; these effects can influence the separation of the dopamine and ascorbic acid voltammetric signals up to 453 mV. Further, the method could be optimized through differential pulse voltammetry to proceed with the analytic determination of dopamine in the presence of ascorbic acid displaying usable analytic parameters, namely: a linearity range of 0–130 μM, a sensitivity of (6.318 ± 0.002) μA mM^?1, a detection limit of (11 ± 0.1) μM, and a quantification limit of (37 ± 0.2) μM, which made it possible to effect the quantification on a commercial pharmaceutical sample.     

Legumes seeds protein isolates in the production of ascorbic acid microparticles

This study evaluated the use of pea (Pisum sativum) and cowpea (Vigna unguiculata) protein isolates (PPI and CPI) in the microencapsulation of ascorbic acid (AA), by spray drying. PPI and CPI were used pure or mixed with maltodextrin (M) as wall materials of AA. The process yield was improved from 66% to 86% by the addition of M (CPI/M and PPI/M); also, AA particles yield was 79%. The AA retention from the drying process was higher in PPI/M (69%) than in CPI/M (66%), and this was attributed to PPI proteolysis profile, demonstrated by the SDS–PAGE electrophoresis. Scanning electron microscopy revealed that AA particles were similarly spherical and shriveled. Mean particle sizes of PPI/M/AA and CPI/M/AA were 7 and 8 μm, respectively. This study showed the exploration of protein isolates from legumes in the development of a microparticulate system containing AA with great potential for use in human health.     

A High Speed VLSI Architecture for Handwriting Recognition

This article presents PAPRICA-3, a VLSI-oriented architecture for real-time processing of images and its implementation on HACRE, a high-speed, cascadable, 32-processors VLSI slice. The architecture is based on an array of programmable processing elements with the instruction set tailored to image processing, mathematical morphology, and neural networks emulation. Dedicated hardware features allow simultaneous image acquisition, processing, neural network emulation, and a straightforward interface with a hosting PC.HACRE has been fabricated and successfully tested at a clock frequency of 50 MHz. A board hosting up to four chips and providing a 33 MHz PCI interface has been manufactured and used to build BEATR IX, a system for the recognition of handwritten check amounts, by integrating image processing and neural network algorithms (on the board) with context analysis techniques (on the hosting PC).     

A simple model for the photocurrent density of a graded band gap CIGS thin film solar cell

A simple model for the photocurrent density of a linearly graded band gap Cu(In,Ga)Se₂ solar cell is presented. Both generation and recombination mechanisms in the space charge region and absorber region of the cell are considered. The carrier collection function and effective absorption coefficient are introduced in the calculations to obtain a more realistic model. The results show that photocurrent density of the graded band-gap solar cell is higher than that with a constant averaged band gap. There is an optimum for grading strength or band gap widening of the absorber region. Recombination current reduces the photocurrent density with a lower reduction in the absorber material than in the depletion region. For longer diffusion lengths (or greater values of carrier collection factor), a higher photocurrent density is obtained except where collection probability is already unity everywhere in the absorber.     

Collective intelligence in law enforcement - The WikiCrimes system

Collaboration is on the rise, primordially leveraged by the Web 2.0 in which the difference between information producer and consumer decreases significantly. In this paper we describe WikiCrimes, an example of a Web 2.0 application that offers a collaborative environment based on the use and direct manipulation of maps, in order to register and research criminal events. WikiCrimes is driven by three goals: (i) to give more transparency and publicity to criminal information, (ii) to provide means for citizen prevention, and (iii) to reduce the phenomenon of under-reporting (crimes that are not notified to authorities). In the paper we pay particular attention to the fact that in this context, finding the equilibrium between people’s participation and information credibility is crucial. Anonymous mass collaboration is the easiest way to receive information; however, the credibility of the received information is depreciated, because the source of information is unknown. We particularly concentrate on the ways we have created to keep the “participation vs. reliability of information” trade-off at good level. The reputation model is the main component created with this purpose. The experiences and the obstacles we are facing in the implementation of the project are the subjects of discussion and analyses.     

Catalytic activity evaluation for hydrogen production via autothermal reforming of methane

A nickel catalyst (5.75 wt.%) supported on gamma-alumina was evaluated through autothermal reforming of methane (ATR). The reforming process was pointed to hydrogen production, following thermodynamic and stoichiometric predictions. The catalyst was characterised by several methods including atomic absorption spectroscopy (AAS), B.E.T.-N₂, X-ray diffraction (XRD), scanning electron microscope (SEM) and thermal analyses (thermogravimetry, TG; derivate thermogravimetry, DTG; and differential thermal analysis, DTA). Experimental evaluations in a fixed-bed reactor (1023–1123 K, 1.00 bar, 150–400 cm³/min feed) presented methane conversions in the range of 40–65%. The effluent mixtures provided hydrogen yields in the range of 78–84%, carbon monoxide 3–14%, and carbon dioxide 5–18%. High molar H₂/CO ratios, ranging from 8 to 90, were obtained. Operating autothermal conditions (excess of steam, 1023–1123 K, 1.00 bar) provided low coke formation and high hydrogen selectivity (81%) for methane reforming.