Processing and Physicochemical Properties of Magnetite Nanoparticles Coated with L. Extract.

In this work, L. extract has been used in the synthesis and direct coating of magnetite (FeO) nanoparticles ~12 nm, providing a surface layer of polyphenol groups (-OH and -COOH). This contributes to the development of nanocarriers and triggers different bio-applications.

Photoacoustic characterization of wheat bread mixed with .

Photoacoustic spectroscopy is applied to evaluate the impact of at different concentrations (0, 1.25, 2.5, 5 and 10%) on the elaboration, sanity, texture, and color of wheat bread.

Chemical synthesis and optical, structural, and surface characterization of InP-InO quantum dots.

InP-InO colloidal quantum dots (QDs) synthesized by a single-step chemical method without injection of hot precursors (one-pot) were investigated. Specifically, the effect of the tris(trimethylsilyl)phosphine, P(TMS), precursor concentration on the QDs properties was studied to effectively control the size and shape of the samples with a minimum size dispersion. The effect of the P(TMS) precursor concentration on the optical, structural, chemical surface, and electronic properties of InP-InO QDs is discussed.

Lentil sprouts: a nutraceutical alternative for the elaboration of bread.

The pro-health action of germinated lentils could be useful to be added with wheat flour in the production of box bread. In this work, we spectroscopically evaluate the germinated and non-germinated lentils, and use them at the concentrations of 5 and 10% for the production of box bread. The chemical and physical tests of the bread and its determination of phenolic acids and flavonoids (by HPLC) were also performed.

Simple and portable low frequency lock-in amplifier designed for photoacoustic measurements and its application to thermal effusivity determination in liquids.

The lock-in amplifier is a very useful instrument for observing very small signals under adverse signal-to-noise conditions. In this work, we describe a simple and portable lock-in amplifier designed to be used in photoacoustic measurements. The device was used to measure the thermal effusivity of eight different liquid samples (distilled water, glycerol, acetone, ethanol, 2-propanol, chloroform, hexane, and methanol), as well as the effusivity of acetone in aqueous solution at distinct concentrations, giving good results.

Sodium butyrate increases the effect of the photodynamic therapy: a mechanism that involves modulation of gene expression and differentiation in astrocytoma cells.

Objectives: In order to evaluate the improvement of the photodynamic therapy (PDT) due to sodium butyrate (NaBu), its effectiveness in U373-MG and D54-MG astrocytoma cell lines was evaluated.

Methods: Cells were exposed to delta-aminolevulinic acid (δ-ALA) as a precursor to endogenous photosensitizer protoporphyrin IX (PpIX). In both astrocytoma cells, an important increase by ALA was observed in uroporphyrinogen synthetase gene expression: 1.

Effects of sodium butyrate on cell death induced by photodynamic therapy in U373-MG and D54-MG astrocytoma cell lines.

The damage induced by end products of photodynamic therapy (PDT) in astrocytoma tumors leads to cytotoxicity and cell death. Chromatin modifiers such as sodium butyrate (NaB) induce several genes involved in apoptosis, among others. The PDT improvement was evaluated by the measurement of its effectiveness in the treatment of U373-MG and D54-MG astrocytoma cell lines exposed to NaB.

Interference effects in photoacoustic and reflectance spectroscopies on TiO2/Si structures and TiO2 band gap.

Experimental results of photoacoustic (PAS) and reflectance (RS) spectroscopies of titanium dioxide thin films (TiO2), deposited on Si substrates, are compared in a wide optical range including transparent and absorbent regions of TiO2. Due to the fact that the light modulation frequency f used in the photoacoustic experiments was so low that the thermal diffusion length of the TiO2 (mu = 100 microm) is always larger than the thickness of the studied films, the PAS turns out to be complementary to RS over the entire range. The presence of multiple reflection interference effects makes difficult a direct evaluation of the TiO2 band gap from the PAS signal.

Photothermal techniques applied to the determination of the water vapor diffusion coefficient and thermal diffusivity of edible films.

Water vapor diffusion coefficient (WVDC) and thermal diffusivity (alpha) were determined in gelatin-starch films through photothermal techniques. The effect of different variables in the elaboration of these films, such as starch and glycerol concentrations and pH, were evaluated through the response surface methodology. The results indicated that an increase in the glycerol concentration and pH favored the WVDC of the films.

Thermal diffusivity of nanofluids containing Au/Pd bimetallic nanoparticles of different compositions.

Colloidal suspensions of bimetallic Au/Pd nanoparticles were prepared by simultaneous reduction of the metal ions from their corresponding chloride salts with polymer (PVP) stabilizer. Thermal properties of water containing bimetallic nanoparticles with different nominal compositions (Au/Pd = 12/1, 5/1, 1/1, 1/5) were measured using the mode mismatched dual-beam thermal lens technique to determine the effect of particle composition on the thermal diffusivity of the nanofluids. The characteristic time constant of the transient thermal lens was estimated by fitting the experimental data to the theoretical expression for transient thermal lens.

Phase transitions in the starch-water system studied by adiabatic scanning calorimetry.

We report high-precision measurements of phase transitions in the starch-water system by using for the first time adiabatic scanning calorimetry (ASC). Potato starch and nixtamalized corn flours were studied by this technique as a function of the moisture content. We calculated the percentage of gelatinized starch granules, as a function of the temperature, for both flours.