Electrospinning of Hyperbranched Poly-L-Lysine/Polyaniline Nanofibers for Application in Cardiac Tissue Engineering

Electrospun polyaniline nanofibers are one of the most promising materials for cardiac tissue engineering due to their tunable electroactive properties. Moreover, the biocompatibility of polyaniline nanofibes can be improved by grafting of adhesive peptides during the synthesis. In this paper, we describe the biocompatible properties and cardiomyocytes proliferation on polyaniline electrospun nanofibers modified by hyperbranched poly-L-lysine dendrimers (HPLys). The microstructure characterization of the HPLys/polyaniline nanofibers was carried out by scanning electron microscopy (SEM). It was observed that the application of electrical current stimulates the differentiation of cardiac cells cultured on the nanofiber scaffolds. Both electroactivity and biocompatibility of the HPLys based nanofibers suggest the use this material for culture of cardiac cells and opens the possibility of using this material as a biocompatible electroactive 3-D matrix in cardiac tissue engineering.     

A simple method to prepare high surface area activated carbon from carboxyl methyl cellulose by low temperature physical activation

Activated carbon with high surface area was prepared from sodium salt of carboxyl methyl cellulose by physical activation at 400 °C followed by treatment in boiling water. The carbon was characterized by XRD, SEM, EPR, TG, IR, surface areas and porosity measurements. The carbon showed alkaline reaction in aqueous solution. It showed high surface area and pore volume in comparison to two commercially available carbons.     

Kinetic study of template removal of Al-MCM-41 synthesized at room temperature

The Al-MCM-41 molecular sieve with Si/Al = 20 molar ratio was synthesized at room temperature and characterized by X-ray diffractometry, surface area, thermogravimetry, and infrared spectroscopy. The kinetic study was conducted by Vyazovkin and Ozawa method, in order to verify the activation energy during the Hofmann degradation between 130 and 370 °C, in which most of surfactant removal occurs. The results suggest that the activation energy for template removal is close to 80 kJ mol^?1 lower in Al-MCM-41 synthesized at room temperature, when compared to results obtained for mesopores Al-MCM-41 and MCM-41 synthesized by hydrothermal method. This lower activation energy may be understood as consequence of textural properties, such as higher pore size.     

On-off scheduling schemes for power-constrained electric vehicle charging

In this paper, we study the problem of establishing a dynamic charging schedule of electric vehicles (EVs) at a charging station, assuming that limited power implies that only a limited number of EVs can charge simultaneously. The only control we assume to be available to the charging station is the ability to (at any given time) turn on or off the power supply to any EV, with this tool we want to develop a charging schedule that will satisfy the energy demands of the EVs in their intended deadlines. We propose two distinct approaches to this problem: a discretized time version, based on a greedy-like algorithm, and a continuous time version, based on linear programming. We compare these two approaches and numerically study the improvement they yield in the efficiency of the charging procedure, when applied to simulated data based on real parking data. Finally, we illustrate the flexibility of the models by sketching several possible extensions.     

13C NMR quantification of mono and diacylglycerols obtained through the solvent‐free lipase‐catalyzed esterification of saturated fatty acids

In the present investigation, we studied the enzymatic synthesis of monoacylglycerols (MAG) and diacylglycerols (DAG) via the esterification of saturated fatty acids (stearic, palmitic and an industrial residue containing 87% palmitic acid) and glycerol in a solvent‐free system. Three immobilized lipases (Lipozyme RM IM, Lipozyme TL IM and Novozym 435) and different reaction conditions were evaluated. Under the optimal reaction conditions, esterifications catalyzed by Lipozyme RM IM resulted in a mixture of MAG and DAG at high conversion rates for all of the substrates. In addition, except for the reaction of industrial residue at atmospheric pressure, all of these products met the World Health Organization and European Union directives for acylglycerol mixtures for use in food applications. The products were quantified by ¹³C NMR, with the aid of an external reference signal which was generated from a sealed coaxial tube filled with acetonitrile‐d3. After calibrating the area of this signal using the classical external reference method, the same coaxial tube was used repeatedly to quantify the reaction products. Copyright © 2012 John Wiley & Sons, Ltd.     

A Simple Strategy to Improve the Accuracy of the Injection Step in Batch Injection Analysis Systems with Amperometric Detection

In this study, we describe for the first time the application of an internal standard method to compensate for random errors associated with the injection procedure in batch injection analysis (BIA) systems with multiple pulse amperometric detection. A sequence of potential pulses was selected in such a way that the internal standard (IS) compound was detected individually at one potential pulse and both the IS and analyte, were detected at another potential pulse. The current ratio (I_IS+analyte/I_IS) was used in the construction of the calibration curve and then to compensate for random errors. The use of disposable syringes or manual pipettes in BIA systems increases the robustness of the method and dispenses with skilled operators.     

Zn[aminoacid]2 hybrid materials applied as heterogeneous catalysts in the synthesis of β-enaminones

Hybrid materials have seized attention from scientific community mainly as heterogenic catalysts in organic reactions on a large scale succeeding in some organic compounds with high yields. One of the most important classes of hybrid materials used for this purpose involves the complexation of Zn and aminoacids. Herein, we introduced Zn[Pro]₂ and Zn[Gly]₂ in the synthesis of several β-enaminones via solvent free protocol and using an ultrasound device.     

Evaluation of a Brazilian ion chromatography interlaboratory study

This paper describes a Brazilian interlaboratory program study on anion measurement in synthetic water. The program described is promoted regularly since 2007 and recommended the use of ion chromatography as analytical technique for all participant laboratories. Two samples (X and Y) with different anion (fluoride, chloride, nitrite-N, nitrate-N, sulfate and phosphate-P) concentration levels were twice distributed in 2011. Each sample on each round had the homogeneity, and the stability tested for a period of 15 days. Upon ensuring the homogeneity and stability, the samples were distributed to 39 laboratories located around the country. The aim of this study was to verify the laboratories’ precision and to establish the measurement comparability among Brazilian laboratories that routinely use ion chromatography for water sample analysis. It was also possible to identify the most frequent sources of systematic and random errors for each measured anion, related to the ion chromatography technique. Some specific metrological issues related to the geographical region are discussed.