Sintering of (Cu0.25Ni0.25Zn0.50)Fe2O4 Ferrite

A study has been conducted on the sintering of a ceramic ferrite having the composition (Cu_0.25Ni_0.25Zn_0.50)Fe₂O₄. The study analyzes the evolution of ferrite relative to density and microstructure with peak sintering temperature and dwell time at peak temperature. The densification and grain-growth rates are correlated with average grain size, relative density, and temperature. Corresponding rate-controlling diffusion mechanisms are proposed.     

Enzymatic browning in avocado (Persea americana) revisited: History,advances, and future perspectives

Considering nearly 80 years of research regarding one of the enzymes responsible for catalyzing the formation of pigments in higher animals, plants, fungi and bacteria, this review will focus on collecting and categorizing the existing information about polyphenol oxidase (PPO) in fruits, with particular emphasis on the information in relation to avocado, which is one of the hardiest species in terms of inactivation, has documented dual activity (EC 1.14.18.1/EC 1.10.3.1), and represents one of the oldest challenges for food science research and fruit processors.

It is expected that this review will contribute to the further development of the field by highlighting the questions that have arisen during the characterization of PPO, the progress that has been made and the questions that remain today, in addition to new methodologies that are being applied to study this system. Holistic methodologies offer unexplored potential for advancing our understanding of the complex phenomena that govern PPO activity in fruits, because these methodologies will enable the characterization of this family of enzymes in all of its complexity. Subsequently, it will be possible to develop better techniques for controlling enzymatic browning in this valuable fruit.     

Melt extruded nanocomposites of polybutylene adipate‐co‐terephthalate (PBAT) with phenylbutyl isocyanate modified cellulose nanocrystals

Traditional commodity polymers are widely used in several disposable or short‐life items and take hundreds of years to decompose in nature. These polymers could be replaced in several uses by biodegradable polymers, like polybutylene adipate‐co‐terephthalate (PBAT) studied in this work. For this, nonetheless, it is necessary to improve some of the PBAT properties, like mechanical resistance and barrier properties. In this work, cellulose nanocrystals (CNC) were incorporated in PBAT with this intention, through melt extrusion. Aiming to avoid CNC aggregation during the drying and extrusion process, a CNC chemical modification with phenylbutyl isocyanate was done. It was possible to obtain PBAT‐CNC melt extruded composites with an elastic modulus 55% higher and water vapor permeability 63% lower than the values of the pure polymer, without compromising PBAT biodegradation. Therefore, the composites prepared with these enhanced properties have great potential as substitutes for traditional commodity polymers. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43678.     

In vitro toxicity evaluation of hydrogel–carbon nanotubes composites on intestinal cells

Composite materials based on carbon nanotubes (CNT) and polymeric hydrogels have become the subject matter of major interest for use as carriers in drug delivery research. The aim of this study was to evaluate the in vitro cytotoxicity of the hydrogel–carbon nanotube–chitosan (hydrogel–CNT–CH) composites on intestinal cells. Oxidized CNT were wrapped with chitosan (CH), Fourier transform infrared (FT‐IR) analysis suggest that oxidized CNT interact with CH. Transmission electron microscopy (TEM) images show a CH layer lying around CNT. Chitosan wrapped CNT were incorporated to poly (acrylamide‐co‐acrylic acid) hydrogels. Swelling behavior in buffers at different pH were evaluated and revealed a significantly lower swelling when it is exposed to a acid buffer solution (pH 2.2). Mechanical properties were evaluated by measurements of elasticity and the material with CNT showed better mechanical properties. The incorporation and liberation of Egg Yolk Immunoglobulin from hydrogel–CNT–CH were also assessed and it revealed an improved performance. To evaluate the effect of these nanocomposites on cellular redox balance, intestinal cells were exposed to hydrogel–CNT–CH composites and antioxidant enzymes were assessed. Cytotoxicity and apoptosis were also evaluated. Hydrogel–CNT–CH composites induce no oxidative stress and there were no evidence of cytotoxicity or cell death. These preliminary findings suggest that hydrogel–CNT–CH composites show improved properties and good biocompatibility in vitro making these biomaterials promising systems for drug delivery purposes. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41370.     

Development of a nanocomposite of polypropylene with biocide action from silver nanoparticles

This article presents the production of films based on blends of polypropylene (PP) and modified PP with the insertion of silver nanoparticles (AgNPs) produced to generate a bactericidal effect. The 50/50 blend of PP and PP modified by irradiation in acetylene at a dose of 12.5 kGy was processed in a twin‐screw extruder. The addition of AgNPs in poly(N‐vinyl‐2‐pyrrolidone) (PVP) solution was performed during processing in the extruder. The material was characterized by ultraviolet–visible spectroscopy, scanning electron microscopy, energy‐dispersive spectroscopy, transmission electron microscopy, cytotoxicity assay, and a reduction in colony‐forming units. The PP–PVP1% AgNP film showed silver particles in the nanoscale, presented no cytotoxicity for mammalian cells, and presented antimicrobial effects against Gram‐negative Escherichia coli and Gram‐positive Staphylococcus aureus bacteria. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42218.     

Salicylketoximes That Target Glucose Transporter 1 Restrict Energy Supply to Lung Cancer Cells

The glucose transporter GLUT1 is frequently overexpressed in most tumor tissues because rapidly proliferating cancer cells rely primarily on glycolysis, a low‐efficiency metabolic pathway that necessitates a very high rate of glucose consumption. Because blocking GLUT1 is a promising anticancer strategy, we developed a novel class of GLUT1 inhibitors based on the 4‐aryl‐substituted salicylketoxime scaffold. Some of these compounds are efficient inhibitors of glucose uptake in lung cancer cells and have a notable antiproliferative effect. In contrast to their 5‐aryl‐substituted regioisomers, the newly synthesized compounds reported herein do not display significant binding to the estrogen receptors. The inhibition of glucose uptake in cancer cells by these compounds was further observed by fluorescence microscopy imaging using a fluorescent analogue of glucose. Therefore, blocking the ability of tumor cells to take up glucose by means of these small molecules, or by further optimized derivatives, may be a successful approach in the development of novel anticancer drugs.     

Forecasting electricity prices and their volatilities using Unobserved Components

The liberalization of electricity markets more than ten years ago in the vast majority of developed countries has introduced the need of modelling and forecasting electricity prices and volatilities, both in the short and long term.Thus, there is a need of providing methodology that is able to deal with the most important features of electricity price series, which are well known for presenting not only structure in conditional mean but also time-varying conditional variances.In this work we propose a new model, which allows to extract conditionally heteroskedastic common factors from the vector of electricity prices. These common factors are jointly estimated as well as their relationship with the original vector of series, and the dynamics affecting both their conditional mean and variance. The estimation of the model is carried out under the state-space formulation.The new model proposed is applied to extract seasonal common dynamic factors as well as common volatility factors for electricity prices and the estimation results are used to forecast electricity prices and their volatilities in the Spanish zone of the Iberian Market.Several simplified/alternative models are also considered as benchmarks to illustrate that the proposed approach is superior to all of them in terms of explanatory and predictive power.     

Recovery of Aromatic Aglycones from Grape Pomace Winemaking By-Products by Using Liquid-Liquid and Pressurized-Liquid Extraction

The potential of winemaking grape pomace by-products as a source of glycosidic aroma precursors that under enzymatic hydrolysis might release aroma compounds has been evaluated. Two different extraction methodologies, liquid–liquid and pressurized liquid extraction (LLE and PLE) were employed. Solid phase extraction (SPE)-GC-MS analysis of the hydrolyzed LLE glycosidic extract revealed 22 aroma compounds belonging to different chemical families (terpenes, C13 norisoprenoids, vanillines, etc.). Response surface methodology was employed to study the effect of the most significant PLE experimental variables (temperature and solvent composition) on the extraction of aromatic aglycones. The parameters of the model were estimated by multiple linear regressions. Most of the aroma compounds showed an adequate fit to the calculated model (18 compounds from 22 with R ²?>?0.8). The application of the optimized PLE conditions (50 % of ethanol in the hydroalcoholic solution) and 90 °C showed higher extraction yield of aglycones when comparing with the extraction yield obtained by LLE.