Influence of laser repetition rate on ferroelectric properties of pulsed laser deposited BaTiO3 films on platinized silicon substrate

BaTiO₃ thin films were deposited by pulsed laser deposition on Pt–Si at different laser pulse repetition frequencies. X-ray diffraction spectra show that preferred oriented films can be grown by adjusting the pulse repetition frequency. Enhanced dielectric and ferroelectric properties obtained in films deposited at 1 Hz is attributed to preferred orientation, low strain and homogeneous grain distribution. The films deposited at 1 Hz show an impressive remanent polarization of 21.4 μC/cm² with a coercive field of 70.0 kV/cm. The shift in Curie temperature, which stems from changing the laser pulse repetition frequency, is associated with the strain state in the film.     

Market Power Issues in Bid-Based Hydrothermal Dispatch

The objective of this work is to investigate market power issues in bid-based hydrothermal scheduling. Initially, market power was simulated with a single stage Cournot–Nash equilibrium model. In this static model the equilibrium was calculated analytically. It was shown that the total production of N strategic agents is smaller than the least-cost solution by a factor of (N/(N+1)). Market power analysis for multiple stages was then carried through a stochastic dynamic programming scheme, where the decision in each stage and state is the Cournot–Nash equilibrium of a multi-agent game. Case studies with data taken from the Brazilian system are presented.     

Sample Preparation for the Determination of Metals in Food Samples Using Spectroanalytical Methods—A Review

Abstract

The present article gives an overview of recent publications and modern techniques of sample preparation for food analysis employing atomic and inorganic mass spectrometric techniques, such as flame atomic absorption spectrometry, chemical vapor generation atomic absorption and atomic fluorescence spectrometry, graphite furnace atomic absorption spectrometry, inductively coupled plasma optical emission spectrometry, and inductively coupled plasma mass spectrometry. Among the most frequently applied sample preparation techniques for food analysis are dry ashing, usually with the addition of an ashing aid, and acid digestion, preferably with the assistance of microwave energy. Slurry preparation, particularly with the assistance of ultrasound, is increasingly used to reduce acid consumption and sample preparation time. Direct analysis of solid samples is gaining importance in the field of food analysis as it offers the highest sensitivity, avoids the use of acids and other aggressive reagents, makes possible the analysis of micro‐samples, and can be applied for fast screening analysis, e.g., of fresh meat.     

Perturbative symplectic field theory and Wigner function

We study relativistic quantum field theories in phase space, based on representations of the Poincaré group, using the Moyal product. We develop a perturbative theory for quantizing fields, with functional methods in phase space. The two-point function is related to relativistic Wigner functions for bosons and fermions. As an example we analyze the complex scalar field with quartic self-interaction.     

Spin-2 Fields and Helicity

By considering the irreducible representations of the Lorentz group, an analysis of the different spin-2 waves is presented. In particular, the question of the helicity is discussed. It is concluded that, although from the point of view of representation theory there are no compelling reasons to choose between spin-2 waves with helicity σ=±1 or σ=±2, consistency arguments of the ensuing field theories favor waves with helicity σ=±1.     

Wavelet-based dynamic time warping

Dynamic Time Warping (DTW), a pattern matching technique traditionally used for restricted vocabulary speech recognition, is based on a temporal alignment of the input signal with the template models. The principal drawback of DTW is its high computational cost as the lengths of the signals increase. This paper shows extended results over our previously published conference paper, which introduces an optimized version of the DTW that is based on the Discrete Wavelet Transform (DWT).     

Chromatographic aspects in high throughput liquid chromatography/mass spectrometry

Important parameters to consider when developing a liquid chromatography/mass spectrometry (LC/MS) method are buffer type and concentration, and column geometry. In the work presented here the choice of buffer for the analysis of basic compounds using a polar embedded phase (HyPURITYtrade mark ADVANCE) is illustrated for the analysis of tricyclic antidepressants. Method transfer from a 4.6 mm i.d. column to a 2.1 mm i.d. column is demonstrated for the analysis of triazines and anabolic steroids and their metabolites, with no change in selectivity and with added speed of analysis. Analysis of eight beta-blockers is achieved in 65 seconds by using a short 30 x 4.6 mm C18 column.     

Molecular Hybridization Strategy on the Design,Synthesis, and Structural Characterization of Ferrocene-N-acyl Hydrazones as Immunomodulatory Agents

Immunomodulatory agents are widely used for the treatment of immune-mediated diseases, but the range of side effects of the available drugs makes necessary the search for new immunomodulatory drugs. Here, we investigated the immunomodulatory activity of new ferrocenyl-N-acyl hydrazones derivatives (SintMed(141–156). The evaluated N-acyl hydrazones did not show cytotoxicity at the tested concentrations, presenting CC₅₀ values greater than 50 µM. In addition, all ferrocenyl-N-acyl hydrazones modulated nitrite production in immortalized macrophages, showing inhibition values between 14.4% and 74.2%. By presenting a better activity profile, the ferrocenyl-N-acyl hydrazones SintMed149 and SintMed150 also had their cytotoxicity and anti-inflammatory effect evaluated in cultures of peritoneal macrophages. The molecules were not cytotoxic at any of the concentrations tested in peritoneal macrophages and were able to significantly reduce (p < 0.05) the production of nitrite, TNF-α, and IL-1β. Interestingly, both molecules significantly reduced the production of IL-2 and IFN-γ in cultured splenocytes activated with concanavalin A. Moreover, SintMed150 did not show signs of acute toxicity in animals treated with 50 or 100 mg/kg. Finally, we observed that ferrocenyl-N-acyl hydrazone SintMed150 at 100 mg/kg reduced the migration of neutrophils (44.6%) in an acute peritonitis model and increased animal survival by 20% in an LPS-induced endotoxic shock model. These findings suggest that such compounds have therapeutic potential to be used to treat diseases of inflammatory origin.     

Microchip free-flow electrophoresis on glass substrate using laser-printing toner as structural material

In this work, a microfluidic free-flow electrophoresis device, obtained by thermal toner transferring on glass substrate, is presented. A microdevice can be manufactured in only 1 h. The layout of the microdevice was designed in order to improve the fluidic and electrical characteristics. The separation channel is 8 microm deep and presents an internal volume of 1.42 microL. The deleterious electrolysis effects were overcome by using a system that isolates the electrolysis products from the separation channel. The Joule heating dissipation in the separation channel was found to be very efficient up to a current density of 8.83 mA/mm(2) that corresponds to a power dissipation per unit volume of running electrolyte of 172 mW/microL. Promising results were obtained in the evaluation of the microdevices for the separation of ionic dyes. The microfluidic device can be used for a continuous sample pretreatment step for micro total analysis system.     

Effect of europium(III) chloride on the aggregation behavior of sodium dodecyl sulfate

The effect of EuCl3 on the aggregation processes of sodium dodecyl sulfate was investigated. Electrical conductivity data, combined with Eu(III) luminescence measurements, suggest that the formation of micelles involving EuCl3 and SDS occurs at low SDS concentration; the formation of these mixed aggregates was also monitored by light scattering, which indicates that the addition of EuCl3 to SDS concentration at values below the critical micelle concentration of the pure surfactant results in a much higher light scattering than that found just with SDS micelles. It was also found that the Eu(III)/DS- complexes are formed with a binding ratio which varies between 20 and 4, depending on the initial concentration of Eu(III). As the concentration increases, turbidity occurs initially, but solutions become clear subsequently. In contrast to the behavior of SDS in the presence of aluminum(III), no flocculation was observed. From the analysis of electrical conductivity data and comparison with other systems, it is suggested that growth of aggregates happens, probably with formation of nonspherical systems. At the highest concentrations these may involve just Eu(III) and DS- ions. The effect of temperature on the SDS micellization process was studied. The calculated free energy of SDS micellization is not dependent on the initial EuCl3 but is dependent on the final balance between the presence of counterions in solution (ionic strength) and the temperature.