Structure and physical properties of nickel manganite NiMn2O4 obtained from nickel permanganate precursor

In this paper we present the structural, magnetic and dielectric properties of ceramic nickel manganite NiMn₂O_4+δ produced by using nickel permanganate Ni(MnO₄)₂xH₂O as a precursor. We have characterized the NiMn₂O_4+δ stoichiometry using quantitative energy-dispersive analysis of X-rays and thermal gravimetry under reducing conditions. Increased oxygen and Mn⁴⁺ contents were detected. X-ray diffraction and Rietveld refinement of X-ray data were carried out. Temperature dependent magnetization measurements were performed and the ferri-magnetic transition was identified at ≈100 K. The ferri-magnetic moment was found to be ≈1μ_B and hysteretic magnetization vs applied field curves were obtained. Dielectric properties were measured using impedance spectroscopy. Two dielectric relaxation processes were detected, which were associated with grain boundary and bulk contributions. The Arrhenius plots of resistivity and the temperature dependent dielectric permittivity were obtained for the two relaxations by means of an equivalent circuit model based on a series of two parallel RC elements.     

Inhibition of Macrophage Oxidative Stress Prevents the Reduction of ABCA-1 Transporter Induced by Advanced Glycated Albumin

We investigated the role of aminoguanidine and benfotiamine on the inhibition of reactive oxygen species (ROS) generation in macrophages induced by advanced glycated albumin (AGE-albumin) and its relationship with cell cholesterol homeostasis, emphasizing the expression of the ATP binding cassette transporter A-1 (ABCA-1). AGE-albumin was made by incubating fatty acid-free albumin with 10 mM glycolaldehyde. ROS production and ABCA-1 protein level were determined by flow cytometry in J774 macrophages treated along time with control (C) or AGE-albumin alone or in the presence of aminoguanidine or benfotiamine. Mitochondrial function was evaluated by oxygraphy. Compared to C-albumin, AGE-albumin increased ROS production in macrophages, which was ascribed to the activities of NADPH oxidase and of the mitochondrial system. Mitochondrial respiratory chain activity was reduced in cells incubated with AGE-albumin. ROS generation along time was associated with the reduction in macrophage ABCA-1 protein level. Aminoguanidine prevented ROS elevation and restored the ABCA-1 content in macrophages; on the other hand, benfotiamine that promoted a lesser reduction in ROS generation was not able to restore ABCA-1 levels. Inhibition of oxidative stress induced by AGE-albumin prevents disturbances in reverse cholesterol transport by curbing the reduction of ABCA-1 elicited by advanced glycation in macrophages and therefore may contribute to the prevention of atherosclerosis in diabetes mellitus.     

Gamma radiation effects on peanut skin antioxidants

Peanut skin, which is removed in the peanut blanching process, is rich in bioactive compounds with antioxidant properties. The aims of this study were to measure bioactive compounds in peanut skins and evaluate the effect of gamma radiation on their antioxidant activity. Peanut skin samples were treated with 0.0, 5.0, 7.5, or 10.0 kGy gamma rays. Total phenolics, condensed tannins, total flavonoids, and antioxidant activity were evaluated. Extracts obtained from the peanut skins were added to refined-bleached-deodorized (RBD) soybean oil. The oxidative stability of the oil samples was determined using the Oil Stability Index method and compared to a control and synthetic antioxidants (100 mg/kg BHT and 200 mg/kg TBHQ). Gamma radiation changed total phenolic content, total condensed tannins, total flavonoid content, and the antioxidant activity. All extracts, gamma irradiated or not, presented increasing induction period (h), measured by the Oil Stability Index method, when compared with the control. Antioxidant activity of the peanut skins was higher than BHT. The present study confirmed that gamma radiation did not affect the peanut skin extracts' antioxidative properties when added to soybean oil.     

Use of Phaseolus vulgaris and Vigna sinensis in a fermented dairy drink

The objective of this work was to develop a new kind fermented dairy drink, partially substituted with clear varieties of Phaseolus vulgaris (caraota) and Vigna sinensis (frijol). The formulation of fermented dairy drinks included sterile extracts of caraota and frijol, as partial substitutes which replaced milk: 10, 20 and 30%. The mixtures were inoculated with 2% of a mixture of Lactobacillus acidophillus, Streptococcus thermophilus and Bifidobacterium sp. and were incubated at 42 degrees C for 7 hours. Mango and guava jams were used as flavorings at 20%. On the basis of the sensorial evaluation the mixtures 10% frijol-mango, 10% frijol-guava, 30% caraota-mango and 20% caraota-guava were selected. In the selected fermented dairy drinks, the levels of protein, soluble and insoluble fiber, available and resistant starches were increased and the protein digestibility was 81%. The technical feasibility of partial substitution of milk with extracts of Phaseolus vulgaris or Vigna sinensis. For the elaboration of a fermented dairy drink similar to the liquid yogurt kind was demonstrated.     

Study of phase separation in blends of silk fibroin and sodium alginate in solution and in solid state

Silk fibroin (SF) and sodium alginate (SA) are natural polymers with many applications as biomaterials. It is possible to make blends with them in order to improve their properties. Those blends are partially miscible; therefore, understanding the mechanism and phase equilibrium of this system is important to better understand the interaction between these natural polymers. This work analyzed the mechanism of phase separation of SF and SA blends with different composition in solution and in the solid state (as membranes) using small angle light scattering with a He-Ne laser. Polymer interaction and conformation were investigated by Fourier-Transform Infrared Spectroscopy with Attenuated Total Reflectance (FTIR-ATR) and X-Ray Diffraction (XRD), and membrane morphology was analyzed by Scanning Electron Microscopy (SEM). SEM images showed interpenetrated globules in the matrix. Light scattering profile for blends in solution and in the solid state showed a peak of intensity suggesting that phase separation occurs by spinodal decomposition.     

Volatiles and Tendency of Radical Formation of Cold‐Pressed Brazil Nut Oil During Ambient Storage

Cold‐pressed Brazil nut oil (BNO) is a value‐added nontimber forest coproduct of market interest, despite the lack of knowledge about its ambient storage stability. The objective of the present study was to investigate oxidative changes in BNO stored in clear and brown glass bottles under retail conditions with a focus on monitoring for the first time the formation of volatile aroma compounds (VAC), the depletion of tocopherol analogs, and the tendency of radical formation. VAC, whose formation continuously increased and correlated with storage time, were detected using headspace‐solid‐phase microextraction‐gas chromatography–mass spectrometry. Depletion of tocopherols was more pronounced for the oil stored in clear glass bottles and the content loss was higher for alpha‐tocopherol than for gamma‐tocopherol. Furthermore, the tendency of radical formation was detected using a spin‐trapping electron spin resonance spectroscopy method, which was demonstrated to be a simpler, faster, and less sample‐demanding tool to monitor the oxidative status of BNO stored under retail conditions and its results significantly correlated with those obtained using traditional methods for the determination of primary oxidation products. However, the simultaneous measurement of key off‐flavor volatiles is recommended for samples with unknown history.     

Modeling of Tension-Stiffening Behavior of Reinforced Concrete Ties Strengthened with Fiber Reinforced Plastic Sheets

A model to analyze the behavior of reinforced concrete tension ties strengthened with fiber reinforced plastic (FRP) laminates is developed that allows introduction of a nonlinear constitutive relationship for materials and bond-slip laws at the steel and FRP interface. Experimental results are introduced and compared with analytical results confirming the model reliability. By using the model, a numerical study is carried out to provide evidence of the influence of the amount of fibers and the tension-stiffening behavior of strengthened elements. Considering elements with the same mechanical percentage of reinforcement but composed of different amounts of steel and fibers, the stiffness is influenced only after steel yielding, even if the crack width is reduced by the external strengthening. Finally, evidence is provided for the reduction of tension stiffening in strengthened elements due to reduction of crack spacing.     

A new Multiobjective Artificial Bee Colony algorithm to solve a real-world frequency assignment problem

Artificial bee colony (ABC) is a recently introduced algorithm that models the behavior of honey bee swarm to address a multiobjective version for ABC, named Multiobjective Artificial Bee Colony algorithm (MO-ABC). We describe the methodology and results obtained when applying the new MO-ABC metaheuristic, which was developed to solve a real-world frequency assignment problem (FAP) in GSM networks. A precise mathematical formulation for this problem was used, where the frequency plans are evaluated using accurate interference information taken from a real GSM network. In this paper, our work is divided into two stages: In the first one, we have accurately tuned the algorithm parameters. Then, in the second step, we have compared the MO-ABC with previous versions of distinct multiobjective algorithms already developed to the same instances of the problem. As we will see, results show that this approach is able to obtain reasonable frequency plans when solving a real-world FAP. In the results analysis, we consider as complementary metrics the hypervolume indicator to measure the quality of the solutions to this problem as well as the coverage relation information.     

School-based prevention of depressive symptoms: A randomized controlled study of the effectiveness and specificity of the penn resiliency program.

The authors investigated the effectiveness and specificity of the Penn Resiliency Program (PRP; J. E. Gillham, L. H. Jaycox, K. J. Reivich, M. E. P. Seligman, & T. Silver, 1990), a cognitive-behavioral depression prevention program. Children (N = 697) from 3 middle schools were randomly assigned to PRP, Control (CON), or the Penn Enhancement Program (PEP; K. J. Reivich, 1996; A. J. Shatté, 1997), an alternate intervention that controls for nonspecific intervention ingredients. Children's depressive symptoms were assessed through 3 years of follow-up. There was no intervention effect on average levels of depressive symptoms in the full sample. Findings varied by school. In 2 schools, PRP significantly reduced depressive symptoms across the follow-up relative to both CON and PEP. In the 3rd school, PRP did not prevent depressive symptoms. The authors discuss the findings in relation to previous research on PRP and the dissemination of prevention programs. (PsycINFO Database Record (c) 2010 APA, all rights reserved)