General results for the beta-modified Weibull distribution

We study in detail the so-called beta-modified Weibull distribution, motivated by the wide use of the Weibull distribution in practice, and also for the fact that the generalization provides a continuous crossover towards cases with different shapes. The new distribution is important since it contains as special sub-models some widely-known distributions, such as the generalized modified Weibull, beta Weibull, exponentiated Weibull, beta exponential, modified Weibull and Weibull distributions, among several others. It also provides more flexibility to analyse complex real data. Various mathematical properties of this distribution are derived, including its moments and moment generating function. We examine the asymptotic distributions of the extreme values. Explicit expressions are also derived for the chf, mean deviations, Bonferroni and Lorenz curves, reliability and entropies. The estimation of parameters is approached by two methods: moments and maximum likelihood. We compare by simulation the performances of the estimates from these methods. We obtain the expected information matrix. Two applications are presented to illustrate the proposed distribution.

Genetic potential of a maize population from Southern Brazil for the modified convergent-divergent selection scheme

Maize (Zea mays L.) is a very important cereal to world-wide economy which is also true for Brazil, particularly in the South region. Grain yield and plant height have been chosen as important criteria by breeders and farmers from Santa Catarina State (SC), Brazil. The objective of this work was to estimate genetic-statistic parameters associated with genetic gain for grain yield and plant height, in the first cycle of convergent-divergent half-sib selection in a maize population (MPA1) cultivated by farmers within the municipality of Anchieta (SC). Three experiments were carried out in different small farms at Anchieta using low external agronomic inputs; each experiment represented independent samples of half-sib families, which were evaluated in randomized complete blocks with three replications per location. Significant differences among half-sib families were observed for both variables in all experiments. The expected responses to truncated selection of the 25% better families in each experiment were 5.1, 5.8 and 5.2% for reducing plant height and 3.9, 5.7 and 5.0% for increasing grain yield, respectively. The magnitudes of genetic-statistic parameters estimated evidenced that the composite population MPA1 exhibits enough genetic variability to be used in cyclical process of recurrent selection. There were evidences that the genetic structure of the base population MPA1, as indicated by its genetic variability, may lead to expressive changes in the traits under selection, even under low selection pressure.

Particle size and concentration of poly(epsilon-caprolactone) and adipate modified starch blend on mineralization in soils with differing textures

The objective of this study was to evaluate the effect of particle size and concentration of poly(F.-caprolactone) and adipate modified starch blend on mineralization in soils with differing textures, comparing it with polyethylene under the same experimental conditions. Two soil types were used: a Kandiudalfic Eutrudox with a clayey texture and an Arenic Hapludult with a sandy texture. The two different plastic specimens were incorporated in the form of plastic films with three increasing particle sizes and six doses, from 0 to 2.5 mg C g(-1) soil. Each plastic dose was incorporated into 200 g of soil placed in a hermetically closed jar at 28 degrees C, and incubated for a 120-day period to determine CO(2) evolution. Once again it was confirmed that polyethylene is almost non-biodegradable, in contrast to PCL/S, which can be defined as a biodegradable material. Soil texture affected the mineralization kinetics of the plastic specimens, with higher values for the clayey soil. No changes in soil microbial biomass-C or -N were observed by adding polyethylene and PCL/S to the soil. Also, no significant differences were observed on seed emergence and development of rice seedlings (Oryza sativa L.) in plastic modified soil. (C) 2009 Elsevier Ltd. All rights reserved.

Cytotoxicity and Endothelial Cell Adhesion of Lyophilized and Irradiated Bovine Pericardium Modified With Silk Fibroin and Chitosan

Grafts of biological tissues have been used since the 1960s as an alternative to the mechanical heart prostheses. Nowadays, the most consolidated treatment to bovine pericardial (BP) bioprostheses is the crosslinking with glutaraldehyde (GA), although GA may induce calcification in vivo. In previous work, our group demonstrated that electron beam irradiation applied to lyophilized BP in the absence of oxygen promoted crosslinks among collagen fibers of BP tissue. In this work, the incorporation of silk fibroin (SF) and chitosan (CHIT) in the BP not treated with GA was studied. The samples were irradiated and then analyzed for their cytotoxicity and the ability of adhesion and growth of endothelial cells. Initially, all samples showed cytotoxicity. However, after a few washing cycles, the cytotoxicity due to acetic acid and ethanol residues was removed from the biomaterial making it suitable for the biofunctional test. The samples modified with SF/CHIT and electron beam irradiated favored the adhesion and growth of endothelial cells throughout the tissue.

Biochemical and biophysical characterization of lysozyme modified by PEGylation

PEGylation is a strategy that has been used to improve the biochemical properties of proteins and their physical and thermal stabilities. In this study, hen egg-white lysozyme (EC 3.2.1.17; LZ) was modified with methoxypolyethylene glycol-p-nitrophenyl carbonate (mPEG-pNP, MW 5000). This PEGylation of LZ produced conjugates that retained full enzyme activity with glycol chitosan, independent of degree of enzyme modification; its biological activity with the substrate Micrococcus lysodeikticus was altered according to its degree of modification. The conjugate obtained with a low degree of mPEG-pNP/NH(2) modification was studied by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF), demonstrating a spectral peak at m/z 19,988 Da with 77% of its original enzymatic activity. Spectroscopic studies of Fourier transform infrared (FIR) and circular dichroism (CD) did not show any relevant differences in protein structure between the native and conjugate LZ. Studies of the effects of pH and temperature on PEGylated LZ indicated that the conjugate was active over a broad pH range, stable at 50 degrees C, and demonstrated resistance to proteolytic degradation. (C) 2010 Elsevier B.V. All rights reserved.

Batch purification of high-purity lysozyme from egg white and characterization of the enzyme modified by PEGylation

PEGylation is one of the most promising and extensively studied strategies for improving the pharmacological properties of proteins as well as their physical and thermal stability. Purified lysozyme obtained from hen egg white by batch mode was modified by PEGylation with methoxypolyethyleneglycol succinimidyl succinato (mPEG-SS, MW 5000). The conjugates produced retained full enzyme activity with the substrate glycol chitosan, independent of degree of enzyme modification, although lysozyme activity with the substrate Micrococcus lysodeikticus was altered according to the degree of modification. The conjugate with a low degree of modification by mPEG-SS retained 67% of its enzyme activity with the M. lysodeikticus substrate. The mPEG-SS was also shown to be a highly reactive polymer. The effects of pH and temperature on PEGylated lysozymes indicated that the conjugate was active over a wide pH range and was stable up to 50 degrees C. This conjugate also showed resistance to proteolytic degradation, remained stable in human serum, and displayed greater antimicrobial activity than native lysozyme against Gram-negative bacteria.</.

Moisture sorption isotherm characteristics of freeze-dried D-limonene emulsions in modified chitosan and maltodextrin

This article reports on modified chitosan as an alternative substance for protecting loss of volatile compounds during freeze drying. Moisture sorption isotherms of freeze-dried D-limonene emulsions in modified chitosan were determined at 15, 25, and 35 degrees C. The data were adjusted to the GAB model. Maltodextrin was used in a parallel experiment. Flavor released from microcapsules was measured. The monolayer humidity, the sorption heat, the diffusivity coefficients, and the surface area of freeze-dried D-limonene emulsions were determined.

EVALUATION OF THE INFLUENCE OF THE PROTEINIC QUALITY OF THE GENETICALLY MODIFIED AND ORGANIC SOY BEANS IN THE GROWTH OF TWO GENERATIONS OF RATS WISTAR

Feijo, T.S., Cardozo, SX, Daleprane, J.B., Sabaa Srur, A.U.O. & Boaventura, G.T. [Evaluation of the influence of the proteinic quality of the genetically modified and organic soy beans in the growth of two generations of rats Wistar.] Avaliacao da influencia da qualidade proteica da soja geneticamente modificada e organica no crescimento de duas geracoes de ratos Wistar. Revista Brasileira de Medicina Veterinaria, 31(3):139-144, 2009. Programa de Pos-Graduacao em Patologia, Hospital Universitario Antonio Pedro. Centro de Ciencias Medicas, Universidade Federal Fluminense. Rua Marques do Parana, 303, Niteroi, RJ 24030-210, Brasil. E-mail: sergian@ufnj.br Sixty four Wistar rats, male of two consecutive generations determined as F(0) and F(1) were used to study the cumulative effect of two variety soy beans, cultivated with organic seasoning and genetically modified, The animals of each generation were divided into three groups of eight rats each fed on diets consisted of organic soy, soy genetically modified and casein respectively. All the animals received water and the diet ad libitum for period of 28 days. Where the diet consumption and the animals weight were evaluated. After statistic analysis of the results no expressive differences were observed on diet consumption, weight variation, protein efficient ratio and food efficiency ratio on same group of animals in the different generations. On the other hand, significant difference was found on final proteinic retention on animal descendants of the same groups; however of different generations. With this, the supplementation of organic soy with L-cistin provided better avail of this protein in relation to the protein of the soy genetically modified. However, this supplementation did not reveal efficiency in keeping the proteinic employment from one generation to another one, since soy varieties presented better performance on F(0) generation when compared with F(1).

Excised Porcine Cornea Integrity Evaluation in an in vitro Model of Iontophoretic Ocular Research

Background/Aims: It is a challenge to adapt traditional in vitro diffusion experiments to ocular tissue. Thus, the aim of this work was to present experimental evidence on the integrity of the porcine cornea, barrier function and maintenance of electrical properties for 6 h of experiment when the tissue is mounted on an inexpensive and easy-to-use in vitro model for ocular iontophoresis. Methods: A modified Franz diffusion cell containing two ports for the insertion of the electrodes and a receiving compartment that does not need gassing with carbogen was used in the studies. Corneal electron transmission microscopy images were obtained, and diffusion experiments with fluorescent markers were performed to examine the integrity of the barrier function. The preservation of the negatively charged corneal epithelium was verified by the determination of the electro-osmotic flow of a hydrophilic and non-ionized molecule. Results: The diffusion cell was able to maintain the temperature, homogenization, porcine epithelial corneal structure integrity, barrier function and electrical characteristics throughout the 6 h of permeation experiment, without requiring CO(2) gassing when the receiving chamber was filled with 25 m M of HEPES buffer solution. Conclusion: The system described here is inexpensive, easy to handle and reliable as an in vitro model for iontophoretic ocular delivery studies. Copyright (C) 2010 S. Karger AG, Basel

Pt-RuO(2) electrodes prepared by thermal decomposition of polymeric precursors as catalysts for direct methanol fuel cell applications

The electrocatalytic activity of Pt and RuO(2) mixed electrodes of different compositions towards methanol oxidation was investigated. The catalysts were prepared by thermal decomposition of polymeric precursors and characterized by energy dispersive X-ray, scanning electronic microscopy, X-ray diffraction and cyclic voltammetry. This preparation method allowed obtaining uniform films with controlled stoichiometry and high surface area. Cyclic voltammetry experiments in the presence of methanol showed that mixed electrodes decreased the potential peak of methanol oxidation by approximately 100 mV (RHE) when compared to the electrode containing only Pt. In addition, voltammetric experiments indicated that the Pt(0.6)Ru(0.4)O(y) electrode led to higher oxidation current densities at lower potentials. Chronoamperometry experiments confirmed the contribution of RuO(2) to the catalytic activity as well as the better performance of the Pt(0.6)Ru(0.4)O(y) electrode composition. Formic acid and CO(2) were identified as being the reaction products formed in the electrolysis performed at 400 and 600 mV. The relative formation of CO(2) was favored in the electrolysis performed at 400 mV (RHE) with the Pt(0.6)Ru(0.4)O(y) electrode. The presence of RuO(2) in Pt-Ru-based electrodes is important for improving the catalytic activity towards methanol electrooxidation. Moreover, the thermal decomposition of polymeric precursors seems to be a promising route for the production of catalysts applicable to DMFC. (C) 2009 International Association for Hydrogen Energy. Published by Elsevier Ltd. All rights reserved.

Impedance characteristics of the diamond/carbon fiber electrodes for electrical double-layer capacitor

The electrochemical performance of carbon fibers (CF) and boron-doped diamond electrodes grown on carbon fiber substrate (BDD/CF) was studied. CF substrates were obtained from polyacrylonitrile precursor heat treated at two different temperatures of 1000 and 2000 degrees C to produce the desirable CF carbon graphitization index. This graphitization process influenced the CF conductivity and its chemical surface, also analyzed from X-ray photoelectron spectroscopy measurements. These three-dimensional CF structures allowed a high incorporation of diamond films compared to other carbon substrates such as glass carbon or HOPG. The electrochemical responses, from these four classes of electrodes, were evaluated focusing their application as electrical double-layer capacitors using cyclic voltammetry and impedance measurements. Cyclic voltammetry results revealed that the electrode formed from BDD grown on CF-2000 presented a typical capacitor behavior with the best rectangular shape, compared to those electrodes of CF or BDD/CF-1000. Furthermore, the BDD/CF-2000 electrode presented the lowest impedance, associated to its significant capacitance value of 1940 mu F/cm(2) taking into account the BDD films. This behavior was attributed to the strong dependence between diamond coating texture and the CF graphitization temperature. The largest surface area of BDD/CF-2000 was promoted by its singular film growth mechanism associated to the substrate chemical surface. (c) 2008 Elsevier B.V. All rights reserved.

Electrocatalytic oxidation of ethanol on Sn((1-x))Ir((x))O(2) electrodes in acid medium

The electrochemical oxidation of ethanol at Sn((1-x))Ir (x) O(2) electrodes (with x = 0.01, 0.05, 0.1 and 0.3) was studied in 0.1 mol L(-1) HClO(4) solution. Electrolysis experiments were carried out and the reaction products were analyzed by Liquid Chromatography. It was found that the amounts of the reaction products depended on the composition of the electrode. In situ infrared reflectance spectroscopy measurements were performed to identify the adsorbed intermediates and to postulate a reaction mechanism for ethanol electrooxidation on these electrode materials. As evidence, acetaldehyde and acetic acid were formed through a successive reaction process. Carbon dioxide was also identified as the end product, showing that the cleavage of the carbon-carbon bond occurred. These results indicate that the synthesized catalysts are able to lead to the total combustion of organic compounds. Analysis of the water bending band at different potentials illustrated its role at the electrode interface.

Electrochemical oxidation of synthetic tannery wastewater in chloride-free aqueous media

The electrochemical treatment of a synthetic tannery wastewater, prepared with several compounds used by finishing tanneries, was studied in chloride-free media. Boron-doped diamond (Si/BDD), antimony-doped tin dioxide (Ti/SnO(2)-Sb), and iridium-antimony-doped tin dioxide (Ti/SnO(2)-Sb-Ir)were evaluated as anode. The influence of pH and current density on the treatment was assessed by means of the parameters used to measure the level of organic contaminants in the wastewater; i.e., total phenols, chemical oxygen demand (COD), total organic carbon (TOC), and absorbance. Results showed that faster decrease in these parameters occurred when the Si/BDD anode was used. Good results were obtained with the Ti/SnO(2)-Sb anode, but its complete deactivation was reached after 4h of electrolysis at 25 mA cm(-2), indicating that the service life of this electrode is short. The Ti/SnO(2)-Sb-Ir anode is chemically and electrochemically more stable than the Ti/SnO(2)-Sb anode, but it is not suitable for the electrochemical treatment under the studied conditions. No significant changes were observed for electrolyses performed at different pH conditions with Si/BDD, and this electrode led to almost complete mineralization after 4 h of electrolysis at 100mAcm(-2). The increase in current density resulted in faster wastewater oxidation, with lower current efficiency and higher energy consumption. Si/BBD proved to be the best electrodic material for the direct electrooxidation of tannery wastewaters. (C) 2010 Elsevier B.V. All rights reserved.

Characterization and voltammetric behavior of Pt(y)Mo(z)O(x)/C electrodes prepared by the thermal decomposition of polymeric precursors

Carbon-supported catalysts containing platinum and molybdenum oxide are prepared by thermal decomposition of polymeric precursors. The Pt(y)Mo(z)O(x)/C materials are characterized by energy dispersive X-ray spectroscopy, transmission electron microscopy, and X-ray diffraction. The catalysts present a well-controlled stoichiometry and nanometric particles. Molybdenum is present mainly as the MoO(3) orthorhombic structure, and no Pt alloys are detected. The voltammetric behavior of the electrodes is investigated; a correlation with literature results for PtMo/C catalysts prepared by other methods is established. The formation of soluble species and the aging effect are discussed. (C) 2009 Elsevier B.V. All rights reserved.

Air pollution and antibodies against modified lipoproteins are associated with atherosclerosis and vascular remodeling in hyperlipemic mice

We analyzed the impact of chronic exposure to urban air pollution on the development of atherosclerosis. Hyperlipemic mice (LDLR(-/-)) were submitted to a high fat diet and air pollution for four months. We measured the susceptibility of LDL to oxidative modifications (TBARS), the presence of anti-oxLDL and an apoB-derived peptide (apoB-D) in blood and the degree of atherosclerosis in the aortic arch. Air pollution increased the susceptibility of LDL to oxidation as well as anti-oxLDL and anti-apo-B levels. These levels were even higher than in mice submitted to a high fat diet and non-polluted air. The lipid content of the atherosclerotic plaques in the aorta was increased in groups with a high cholesterol diet independently of the air quality. However, the thickness of the arterial wall was greater in mice fed a high lipid diet with polluted air. Thus, we conclude that urban air pollution exacerbates the susceptibility of LDL to oxidation, atherogenesis and vascular remodeling in hyperlipemic mice and that an immune response accompanies this process. (C) 2009 Elsevier Ireland Ltd. All rights reserved.