Photovoltaic scavenging systems: Modeling and optimization

The interest in embedded portable systems and wireless sensor networks (WSNs) that scavenge energy from the environment has been increasing over the last years. Thanks to the progress in the design of low-power circuits, such devices consume less and less power and are promising candidates to perform continued operation by the use of renewable energy sources. The adoption of maximum power point tracking (MPPT) techniques in photovoltaic scavengers increases the energy harvesting efficiency and leads to several benefits such as the possibility to shrink the size of photovoltaic modules and energy reservoirs. Unfortunately, the optimization of this process under non-stationary light conditions is still a key design challenge and the development of a photovoltaic harvester has to be preceded by extensive simulations. We propose a detailed model of the solar cell that predicts the instantaneous power collected by the panel and improves the simulation of harvester systems. Furthermore, the paper focuses on a methodology for optimizing the design of MPPT solar harvesters for self-powered embedded systems and presents improvements in the circuit architecture with respect to our previous implementation. Experimental results show that the proposed design guidelines allow to increment global efficiency and to reduce the power consumption of the scavenger.     

Optimisation of germination time and temperature on the concentration of bioactive compounds in Brazilian soybean cultivar BRS 133 using response surface methodology

The objective was to optimise the effect of germination time and temperature on the concentration of soluble protein, lunasin, BBI, lectin, saponins and isoflavones in soybean seeds from cultivar BRS 133. Isoflavone and saponin concentrations were analysed by HPLC. Lunasin, Bowman-Birk inhibitor and lectin were analysed by ELISA and western blot. The effects of the variations in germination time and temperature on bioactive compounds were analysed using the response surface methodology (RSM), with a 2² central composite rotational design. Germination of soybean for 42 h at 25 °C resulted in an increase of 61.7% of lunasin, decrease of 58.7% in lectin and 70.0% in lipoxygenase activity. Optimal increases in the concentrations of isoflavone aglycones were observed in combination of 63 h of germination and 30 °C. A significant increase of 32.2% in the concentration of soy saponins was observed in combination of 42 h of germination at 25 °C.     

Natural Antioxidants Protect Against Cadmium-Induced Damage during Pregnancy and Lactation in Rats' Pups

ABSTRACT:  Free-radicals production is involved in the toxicity of cadmium. The aim of this study was to determine whether biochemical changes occurred in the liver and kidney of cadmium exposed pups during gestation and lactation, and additionally to investigate the potential beneficial role of the administration of certain antioxidants against cadmium exposure damage. Pregnant  Wistar  rats received the following treatments as drinking water: (1) Distilled water; (2) Cadmium (10 mg/L); (3) Cadmium + Zinc (20 mg/L) + vitamins A (50000 U/L), C (2 g/L), E (500 mg/L), and B₆ (500 mg/L); (4) Vitamins + Zinc solution. We found an increase in hemolysis and in the aminolevulinic acid dehydratase (δ-ALAD) activity in the erythrocytes among both cadmium-exposed groups. Cadmium exposure increased the production of thiobarbituric acid reactive substances (TBARS), catalase, and alkaline and acid phosphatase activity in both the organs studied. The effect on the enzymatic activity was reduced by the coadministration of vitamins and zinc. Our findings suggest that administration of antioxidants during gestation and lactation could prevent some of the negative effects of cadmium.     

Pervasive computing for interactive virtual heritage

The rapid evolution of pervasive computing technologies enables bringing virtual heritage applications to a new level of user participation. A platform for interactive virtual heritage applications integrates a high-end virtual reality system with wireless, connected portable and wearable computers, facilitating and enhancing user navigation, visualization control, and peer-to-peer information exchange.     

Application limits and data correction in number of molecules and brightness analysis

Number of molecules and Brightness (N&B) has been proposed for measuring the molecular brightness and number of fluorophores in time‐sequence of images, in live cells. If the fluorescently tagged‐proteins are mobile in the illumination volume, the stoichiometry of their oligomers can be derived from the increase of the brightness of the fluorescent dyes due to clustering. We examine aspects concerning extra‐fluctuation effects induced by cell shifts and photobleaching, which yield large overestimates of the clusters size and sub‐unit counts. We develop an offline corrective approach consisting in frame re‐alignment and boxcar filtering for recovering precision of the analysis. Using simulations we derive general criteria for approaching this analysis, and assess the application limits of the corrective procedure. We tested the approach in extreme experimental conditions (few pixels, large extra‐variance perturbations), in which we analyzed the minimal increases of brightness as that expected between a monomeric and dimeric GPI‐mEGFP constructs. We show how most of the perturbing effects can be abolished, and obtain the correct the brightness of GPI‐mEGFP monomers and dimers. Microsc. Res. Tech. 76:1135–1146, 2013. © 2013 Wiley Periodicals, Inc.     

Questioning the Shanghai Ranking methodology as a tool for the evaluation of universities: an integrative review

Scientometrics - This integrative review reports on methodological questions about the Shanghai Ranking as a tool for the evaluation of universities, questions that are extensible to other...     

Scientific basis of effective energy resource use and environmentally safe processing of phosphorus-containing manufacturing waste of ore-dressing barrows and processing enterprises

Waste barrows of ore-dressing and processing enterprises have a special role among anthropogenic deposits where fine finders are stored, intensifying their amenability to wind and water erosion. Rock barrows occupy much larger territories than factory lands, leading to environmental pollution. Herein, we create a fundamental physical and chemical basis for the effective use of energy resources and environmentally safe processing of ore-dressing waste products, which allows for transformation of raw fine finders stored in tailing dumps into competitive products and decreases the amount of resources aimed toward ground disposal. It will also assure the extermination of tailing dumps and grounds. This can also minimize negative environmental impact and stabilize further development. For this purpose, a mathematical model of a complex chemical energy technological system (CETS) aimed at manufacturing phosphorite pellets has been developed. Large-scale models of multistage chemical energy technological processes of baking and coking moving dense multilayer masses of phosphorite pellets, which differ in their raw material physical, chemical, and granulometric characteristics, have also been developed. Additionally, special multilayer algorithms for formulating making decisions concerning optimal energy resource effectiveness management of CETS manufacturing phosphorite pellets have been developed. They differ in the quality ratings of the prepared pellets in the characteristics of raw phosphate materials. These calculations also consider the impact of controlling the actions of temperature and speed of gas supply for the exchange of having a dynamic dense multilayer pellets mass, which allows for using an available potential of increased effectiveness to maximize energy resources of CETS.

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Acrylic bone cements incorporating polymeric active components derived from salicylic acid: curing parameters and properties

A methacrylic monomer derived from salicylic acid, 5-hydroxy-2-methacrylamido benzoic acid, 5-HMA, was incorporated with 2-hydroxyethyl methacrylate, (HEMA), in different proportions to the liquid phase of classical bone cement formulations. The monomer 5-HMA shows the ability to form molecular complexes with calcium atoms in order to improve osteointegration in the application of bone cement formulations used for the fixation of joint prostheses such as knee and hip. Kinetic parameters, peak temperature and setting time of the bone cement formulations prepared were determined, obtaining lower peak temperature values when 5-HMA was incorporated, with respect to classical acrylic bone cements based on PMMA. Mechanical and thermal properties as well as surface energy values, have been determined for all cured bone cement formulations. © 1998 Kluwer Academic Publishers     

Coherent low-energy electron diffraction on individual nanometer sized objects

Today's structural biology techniques require averaging over millions of molecules to obtain detailed structural information. Derivation of the molecular structure from a scattering experiment with just one single 3D-molecule imposes major challenges. Coherent and damage-free radiation is needed to ensure sufficient elastic scattering events before destroying the molecule and a means to solve the phase problem is wanted. We have devised such a scheme using coherent low-energy electrons shaped into a collimated beam by an electrostatic microlens. Initial experiments using a carbon nanotube sample demonstrate the feasibility of coherent low-energy electron diffraction on an individual nanometer-sized object.