A generalized two point ellipsoidal anisotropic ray tracing for converted waves

Rocks can be anisotropic due to a variety of reasons. When estimating rock velocities from seismic data, failure to introduce anisotropy into earth models could generate distortions in the final images that can have enormous economic impact. To estimate anisotropic earth velocities by tomographic methods, it is necessary to trace rays or to solve the wave equation in models where anisotropy has been properly considered. Thus, in this work we present a 3-D generalized ellipsoidal travel time formulation that allow us to trace rays in an anisotropic medium. We propose to trace rays in anisotropic media by solving a set of nonlinear optimization problems, where the group velocities for P and S wave propagation modes are 3-D ellipsoidal approximations that have been recently obtained. Moreover, we prove that this 3-D ellipsoidal anisotropic ray tracing formulation is a convex nonlinear optimization problem, and therefore any solution of the problem is a global minimum. Each optimization problem is solved by the global spectral gradient method, which requires first order information and has low computation and low storage requirements. Our approach for tracing rays in anisotropic media is a generalization in the sense that handles titled axis of symmetry and, close to the axis of symmetry, it is an accurate formulation for 2-D transversely isotropic media and 3-D orthorhombic media, depending on the input parameters. Moreover, this formulation gives the exact ray trajectories in 2-D and 3-D homogeneous isotropic media. The simplicity of the formulation and the low computational cost of the optimization method allow us to present a variety of numerical results that illustrate the behavior and computational advantages of the approach, and the difficulties when working in anisotropic media. Partially supported by Fonacit project UCV-97-003769     

Electroconvulsive Therapy in Psychiatric Disorders: A Narrative Review Exploring Neuroendocrine–Immune Therapeutic Mechanisms and Clinical Implications

Electroconvulsive therapy (ECT) is based on conducting an electrical current through the brain to stimulate it and trigger generalized convulsion activity with therapeutic ends. Due to the efficient use of ECT during the last years, interest in the molecular bases involved in its mechanism of action has increased. Therefore, different hypotheses have emerged. In this context, the goal of this review is to describe the neurobiological, endocrine, and immune mechanisms involved in ECT and to detail its clinical efficacy in different psychiatric pathologies. This is a narrative review in which an extensive literature search was performed on the Scopus, Embase, PubMed, ISI Web of Science, and Google Scholar databases from inception to February 2022. The terms “electroconvulsive therapy”, “neurobiological effects of electroconvulsive therapy”, “molecular mechanisms in electroconvulsive therapy”, and “psychiatric disorders” were among the keywords used in the search. The mechanisms of action of ECT include neurobiological function modifications and endocrine and immune changes that take place after ECT. Among these, the decrease in neural network hyperconnectivity, neuroinflammation reduction, neurogenesis promotion, modulation of different monoaminergic systems, and hypothalamus–hypophysis–adrenal and hypothalamus–hypophysis–thyroid axes normalization have been described. The majority of these elements are physiopathological components and therapeutic targets in different mental illnesses. Likewise, the use of ECT has recently expanded, with evidence of its use for other pathologies, such as Parkinson’s disease psychosis, malignant neuroleptic syndrome, post-traumatic stress disorder, and obsessive–compulsive disorder. In conclusion, there is sufficient evidence to support the efficacy of ECT in the treatment of different psychiatric disorders, potentially through immune, endocrine, and neurobiological systems.     

Analyses of selected non-authorized insecticides in peppers by gas chromatography/mass spectrometry and gas chromatography/tandem mass spectrometry

Two methods based on gas chromatography coupled with mass spectrometry and tandem mass spectrometry analyzers are described for the identification, confirmation and quantitation of two EU-banned insecticides: isocarbophos and isofenphos-methyl, detected in recent monitoring programmes in pepper samples. The proposed methodologies involved a liquid–liquid extraction with acetonitrile followed by a cleanup step by dispersive solid-phase extraction using primary–secondary amine as sorbent material. Recovery studies performed on peppers spiked at different fortification levels (10 and 50 μg kg⁻¹) yielded average recoveries in the range 85–98% with RSD values below 8%. Identification, confirmation and quantitation were carried out by gas chromatography/mass spectrometry (GC–MS) in selected ion monitoring mode and gas chromatography/tandem mass spectrometry (GC–MS/MS) using an ion trap operating in the multiple reaction monitoring (MRM) mode. The obtained limits of detection (LODs) were in the range 0.1–0.3 μg kg⁻¹, depending on the technique. The proposed methods were successfully applied to the analysis of suspected pepper samples.     

Melt behaviour of poly(ethylene oxide)-poly(vinyl acetate) blends

Summary The compatibility of blends of poly(vinyl acetate) and poly(ethylene oxide) has been studied by rheological and thermo-optical analysis. Results from experiments point to the conclusion that there is extensive mixing between the segments of the two macromolecules in the blend. The interaction between the two polymers is manifested by a decrease in the melting point and a continuous decrease in viscosity with decreasing POE content in the mixture.     

Volatile composition of partially fermented wines elaborated from sun dried Pedro Ximénez grapes

In this work, we used a cell immobilisation system consisting of Penicillium chrysogenum fungi (GRAS) bound to the osmotolerant yeast strains Saccharomyces cerevisiae X4 and X5 for the partial fermentation of raisin musts. The resulting wines were compared with others obtained by partial fermentation of musts with free yeasts and with a traditionally produced sweet wine (i.e. without fermentation of the must). The analysis of volatile compounds grouped by aroma series showed the partially fermented musts had a more complex aroma than the traditional wine. Specially prominent among aroma series was that of ripe fruit, followed by the milky and chemical series. The volatiles with the greatest impact on wine aroma as assessed in terms of odour activity were ethyl hexanoate, ethyl octanoate, butyrolactone, isoamyl alcohols, acetaldehyde, ethyl acetate, 2,3-butanediol, acetoin and 2,3-butanedione. A cluster analysis according to the Ward method was performed to assess the similarity between the traditional sweet wine and those obtained by partial fermentation with free and immobilised yeasts revealed small differences between the wines obtained with free and immobilised yeasts, and marked differences between partially fermented and traditionally obtained sweet wine. The wines provided by immobilised yeasts were the most appreciated in the sensory analysis (especially those obtained with X4 yeasts).     

Efficient Extraction of Olive Pulp and Stone Proteins by using an Enzyme‐Assisted Method

An efficient protein extraction protocol for proteins from olive pulp and stone by using enzymes was developed. For this purpose, different parameters that affect the extraction process, such as enzyme type and content, pH, and extraction temperature and time, were tested. The influence of these factors on protein recovery was examined using the standard Bradford assay, while the extracted proteins were characterized by sodium dodecyl sulfate?polyacrylamide gel electrophoresis (SDS‐PAGE). The best extraction conditions were achieved at pH 7.0 and 5% (v/v) Palatase® 20000 L (lipase) for pulp and Lecitase® Ultra (phospholipase) for stone proteins. The optimal extraction temperature and time were 30 and 40 °C for 15 min for pulp and stone tissues, respectively. Under these conditions, several protein extracts coming from olive fruits of different genetic variety were analyzed, their profiles being compared by SDS‐PAGE. The developed enzyme‐assisted extraction method showed faster extraction, higher recovery, and reduced solvent usage than the nonenzymatic methods previously described in the literature. In the case of stone proteins, different electrophoretic profiles and band intensities were obtained that could be helpful to distinguish samples according to their genetic variety.     

Analysis of Isoflavones in Foods

In recent years the nutritional and bioactive properties of foods are being intensively investigated with a view to control, in addition to food quality, their possible influence on human health. Because of this, there is a growing demand for rapid, selective, sensitive, and validated methods for analysis and quantification. Bioactive plant compounds include those with weak estrogenic activity (phytoestrogens), among which are the isoflavones. Some of the beneficial activities that have been attributed to isoflavones are anticarcinogenic activity, the prevention of cardiovascular disease, the improvement of bone health, and antioxidant activity. The objective of this work is to provide an updated review of the methods used in sample preparation and subsequent analysis for the determination of isoflavones in food samples, including both soybean and soy products, as well as other foods with low isoflavone contents. The review focuses on the most common sample preparation techniques used during the last 10 years, including both conventional solvent extraction and other more recent extraction techniques. Separation and detection methods, including current trends in liquid chromatography analysis, such as the use of monolithic columns or ultra‐high‐pressure liquid chromatography, are also discussed.     

Activation and desensitization properties of native and recombinant kainate receptors

The activation-inactivation properties of membrane currents induced by the rapid application of glutamate or kainate were studied in cultured hippocampal neurons and in HEK cells transfected with a cDNA encoding the GluR6 subunit. The onset of desensitization was rapid and similar in native and recombinant channels (approximately 80 s(-1) of onset rate constant). Recovery from desensitization was slow and agonist-dependent in neurons, proceeding slightly faster in GluR6 receptors. Half-maximal activation (EC50) of native channels was obtained at a glutamate concentration of 330 microM, while the half-maximal steady state desensitization (IC1/2) was attained at 2.8 microM. These values differed from those obtained in recombinant receptors (EC50 = 762 microM and IC1/2 = 0.44 microM). A small window under the crossing point of activation and inactivation curves was observed, indicating that, for some concentrations of either agonist, steady state channel activity could exist. In native receptors, this window presented maximum values at approximately 100 microM for glutamate, which predicted well the potency of glutamate to reduce the GABAergic drive in hippocampal slices. These data indicate that for neuronal kainate receptors, the concentrations for half activation and half inactivation differ by two orders of magnitude such that the maximum response to a maintained concentration of glutamate is small, and the steady state dose response curve is skewed and bell shaped.