Fault-tolerant reversible AC motor drive system

This paper investigates a fault-tolerant three-phase AC/AC converter topology. With such a topology when either one leg of the input rectifier or one leg of the output inverter is lost the power flow between the grid and the load can still be controlled effectively. The topology proposed and its operating principles are presented. The suitable control strategy for the post-fault converter is developed. Experimental results are presented.     

A fast multichannel analyzer for radiation detection applications

This work reports on the development of a multichannel analyzer (MCA) circuit for use in radiation detection. The MCA is based on a fast analog-to-digital converter (ADC) plus a digital circuitry programmed on a complex programmable logic device (CPLD). The ADC digitizes the input signals with high accuracy and low nonlinearity while the CPLD performs the histogramming process of the acquired voltage amplitudes. The MCA basic operations are carried on by a logic state machine implemented in the CPLD, triggered by a 20-MHz clock. This approach has allowed us to reduce the circuit dead time to 200 ns. Other performance parameters are related to the used ADC chips. Results are shown that illustrate competitive results as compared to commercially available MCAs.     

Modeling and Optimal Centralized Control of a Large-Size Robotic Population

This paper describes an approach to the modeling and control of multiagent populations composed of a large number of agents. The complexity of population modeling is avoided by assuming a stochastic approach, under which the agent distribution over the state space is modeled. The dynamics of the state probability density functions is determined, and a control problem of maximizing the probability of robotic presence in a given region is introduced. The Minimum Principle for the optimal control of partial differential equations is exploited to solve this problem, and it is applied to the mission control of a simulated large robotic population     

Pharmacological effects of arginine supplementation in rats with Walker 256 solid tumor

The effects of diet arginine supplementation for those with cancer are controversial. We evaluate the effects of dietetic supplementation with arginine over body weight, growth of tumor, metastatic dissemination, surviving time, amino acid metabolism, haematological changes of the rats with Walker 256 solid tumor. Intragastrical solutions with arginine at 4% and 6%, a standard diet (control) were administered to the animals. The supplementation with arginine was associated with a lower weight gain during the study period (p < 0.05). Surviving time of the rats with solid tumor did not vary significantly between the groups. The rate of metastase was lower in animals with Walker 256 solid tumor supplemented with arginine. The amino acid metabolism was estimulate in the animals after arginine supplementation at 4% and 6%, demonstrated by significant increases in blood levels of arginine, ornitine, citruline, proline and histidine when compared to the control group. Anaemia was less severe in the rats with Walker 256 solid tumor that received arginine supplementation. The results suggest that arginine 6% supplementation may have pharmacologic effect in rats with Walker 256 solid beyond the nutritional one.     

Dietary records used for food consumption evaluation in adolescents: comparison among methods

Given the difficulties surrounding evaluating food consumption, specifically during adolescence, the goal of the present study was to compare different dietary assessment instruments used for this age group. The study was carried out with a group of 60 female adolescents between 14 and 18 years of age. Three repetitions of 24-Hour Recall, three-day Dietary Records and Purchase List of the adolescents and their families were collected. The 24 Hour Recall and Dietary Records had good repeatability, allowing to infer that only one application of one of these instruments was capable of reflecting the ingestion average (or median) of the study population group. The Purchase List allowed us to know the food availability within the context of the individual's conditions. All dietary assessment instruments may contain errors, therefore the choice of the most adequate method must rely on the objectives of the study being developed, as well as the study population.     

Topical delivery of fluconazole: in vitro skin penetration and permeation using emulsions as dosage forms

We investigated in vitro skin penetration and permeation of fluconazole from emulsions containing different penetration enhancers. Fluconazole permeation was high (15-65% of the applied dose) across hairless mouse skin and low (8-9%) across pig ear skin. Permeation across mice skin from a formulation containing propyleneglycol and isopropyl myristate was significantly higher than that observed with the paraffin oil and propyleneglycol or Transcutol® emulsions. With pig skin, the paraffin oil or isopropyl myristate and propyleneglycol emulsions showed similar skin permeation and penetration. However, these emulsions provided epidermal concentrations higher than the minimal inhibitory concentrations for most dermatophytes.     

Maximization of user satisfaction in OFDMA systems using utility‐based resource allocation

In order to keep and/or expand its share of the wireless communication market and decrease churn, it is important for network operators to keep their users (clients) satisfied. The problem to be solved is how to increase the number of satisfied non‐real time (NRT) and real time (RT) users in the downlink of the radio access network of an orthogonal frequency division multiple access system. In this context, the present work proposes a method to solve the referred problem using a unified radio resource allocation (RRA) framework based on utility theory. This unified RRA framework is particularized into two RRA policies that use sigmoidal utility functions based on throughput or delay and are suitable for NRT and RT services, respectively. It is demonstrated by means of system‐level simulations that a step‐shaped sigmoidal utility function combined with a channel‐aware opportunistic scheduling criterion is effective toward the objective of user satisfaction maximization. Copyright © 2014 John Wiley & Sons, Ltd.     

Biodegradation of p-chlorophenol by a microalgae consortium

An aquatic community was recovered from a waste discharge container fed with several aromatic pollutants. After 3 months of selective enrichment with p-chlorophenol and p-nitrophenol, two microalgae species, Chlorella vulgaris and Coenochloris pyrenoidosa, were recovered from the microbial consortium. As an axenic culture, this microalgae consortium was able to remove p-chlorophenol under different photo-regimes. Cultures grown under a 24h light regime were capable of biodegrading 50mg l(-1) of p-chlorophenol within 5 days. Addition of zeolite, an adsorbing material, did not improve the p-chlorophenol removal. However, when p-chlorophenol at 150mgl(-1) was fed to the culture supplemented with zeolite, the growth rate of the consortium improved, but the lag phase was longer (16 against 14 days in the absence of zeolite).     

Influence of MgO content as an additive on the performance of Ni/MgOSiO2 catalysts for the steam reforming of glycerol

Ni catalysts supported on MgOSiO₂ were assessed in the steam reforming reaction of glycerol for the study of the H₂ production and carbon deposition with different MgO contents as additives. The catalysts were prepared with commercial SiO₂ by the aqueous impregnation method and characterized by energy dispersive X-ray spectroscopy, specific surface area, X-ray diffraction, thermogravimetric analysis, X-ray diffraction in situ with O₂, temperature programmed reduction with H₂, X-ray diffraction in situ with H₂, temperature programmed desorption with H₂ and scanning electron microscopy. The glycerol steam reforming reaction took place at 600 °C for 5 h, with a water/glycerol molar ratio of 12/1 at 5 mLh^?1. N₂ was used as the carrier gas. The characterization of the samples showed the interaction of Ni with the support increases with the MgO addition, due to the formation of a NiMg silicate hydrate and MgNiO₂ solid solution; as a result, both metallic area and dispersion also increased. Catalytic results showed similar gaseous products yields (H₂, CH₄, CO and CO₂) for mixed-matrix catalysts, however, a lower carbon deposition on 10 wt%Ni catalyst supported on 30 wt%MgOSiO₂ was observed.     

The Receptor AT1 Appears to Be Important for the Maintenance of Bone Mass and AT2 Receptor Function in Periodontal Bone Loss Appears to Be Regulated by AT1 Receptor

A large number of experimental studies has demonstrated that angiotensin II (Ang II) is involved in key events of the inflammatory process. This study aimed to evaluate the role of Ang II type 1 (AT1) and Ang II type 2 (AT2) receptors on periodontitis. Methods: Experimental periodontitis was induced by placing a 5.0 nylon thread ligature around the second upper left molar of AT1 mice, no-ligature or ligature (AT1-NL and AT1-L), AT2 (AT2-NL or AT2-L) and wild type (WT-NL or L). Alveolar bone loss was scanned using Micro-CT. Cytokines, peptides and enzymes were analyzed from gingival tissues by Elisa and RT-PCR. Results: The blockade of AT1 receptor resulted in bone loss, even in healthy animals. Ang II receptor blockades did not prevent linear bone loss. Ang II and Ang 1-7 levels were significantly increased in the AT2-L (p < 0.01) group compared to AT2-NL and AT1-L. The genic expression of the Mas receptor was significantly increased in WT-L and AT2-L compared to (WT-NL and AT2-NL, respectively) and in AT1-L. Conclusions: Our data suggest that the receptor AT1 appears to be important for the maintenance of bone mass. AT2 receptor molecular function in periodontitis appears to be regulated by AT1.