Manganese Preconcentration and Speciation in Bioaccessible Fraction of Enteral Nutrition Formulas by Cloud Point Extraction (CPE) and Atomic Absorption Spectroscopy

The present study develops a new method for manganese (Mn) preconcentration and speciation in bioaccessible fraction (soluble and dialyzable fraction) of enteral nutrition formulas by cloud point extraction (CPE) and atomic absorption spectroscopy (AAS). For this purpose, a non-ionic surfactant (Triton X-100) and three chelating reagents [8-hydroxyquinoline (8-HQ); 1-phenyl-3-methyl-4-benzoyl-5-pyrazolone (PMBP); and ammonium pyrrolidine dithiocarbamate (APDC)] were used with different operating conditions. The results showed that an efficient extraction of ionic Mn could be achieved with the following conditions: pH?=?10; chelating reagent concentrations of [8-HQ]?=?0.36 M, [PMBP]?=?0.09 M, and [APDC]?=?0.09 M; surfactant Triton X-100 at 25% (w/v), and equilibration temperature-time of 85 °C and 30 min. Limits of detection and quantitation are 0.015 and 0.050 mg L^?1 respectively. Furthermore, when analyzing the bioaccessible fraction of the enteral nutrition formulas, the proposed approach can be used to distinguish between ionic (free) Mn and Mn that has been previously bound to existing substances obtained from enzymatic digestion. These Mn speciation findings can be used to validate results obtained from the bioaccessibility assays.     

DNS of turbulent thermal boundary layers up to Reθ = 2300

A technique, based on the Lund et al. (1998) [1] approach, is introduced in order to numerically prescribe time-dependent turbulent inflow conditions in spatially-developing thermal boundary layers. A major difference with Lund’s approach is that the new multi-scale approach considers different scaling laws for the inner and outer parts of the boundary layer. Direct numerical simulations (DNS) are performed for incompressible zero (ZPG) and adverse (APG) pressure gradient flows. To the best of our knowledge, the present DNS in ZPG flows at a momentum thickness Reynolds numbers (Re_θ) of 2300 represents the evolving thermal boundary layer simulations at the highest Re_θ in the turbulence community. The temperature is treated as a passive scalar with isothermal walls as a boundary condition and a molecular Prandtl number of 0.71. The predicted Stanton number shows fairly good agreement with empirical correlations, and experimental and numerical data from the literature. Moreover, the influences of the Reynolds number and the APG strength on thermal parameters are also examined. Furthermore, the budget of the temperature variance shows a significant increase of production, turbulent diffusion, and dissipation in the buffer layer at higher Reynolds numbers. The main effects of adverse pressure gradients on the temperature field are manifested by a decreasing trend of thermal fluctuations but an increasing trend of the wall-normal turbulent heat fluxes when normalized by wall units as the APG strength is augmented.     

New Results for Prediction of Chaotic Systems Using Deep Recurrent Neural Networks

Neural Processing Letters - Prediction of nonlinear and dynamic systems is a challenging task, however with the aid of machine learning techniques, particularly neural networks, is now possible to...     

Quasi-Diamond Platelet-Shaped Zinc Oxide Nanostructures Display Enhanced Antibacterial Activity

The current study compares the antibacterial activity of zinc oxide nanostructures (neZnO). For this purpose, two bacterial strains, Escherichia coli (ATCC 4157) and Staphylococcus aureus (ATCC 29213) were challenged in room light conditions with the aforementioned materials. Colloidal and hydrothermal methods were used to obtain the quasi-round and quasi-diamond platelet-shape nanostructures. Thus, the oxygen vacancy (V_O) effects on the surface of neZnO are also considered to assess its effects on antibacterial activity. The neZnO characterization was achieved by X-ray diffraction (XRD), a selected area electron diffraction (SAED) and Raman spectroscopy. The microstructural effects were monitored by scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Furthermore, optical absorption ultraviolet visible spectrophotometry (UV-Vis) and X-ray photoelectron spectroscopy (XPS) analyses complement the physical characterization of these nanostructures; neZnO caused 50 % inhibition (IC₅₀) at concentrations from 0.064 to 0.072 mg/mL for S. aureus and from 0.083 to 0.104 mg/mL for E. coli, indicating an increase in activity against S. aureus compared to E. coli. Consequently, quasi-diamond platelet-shaped nanostructures (average particle size of 377.6±10 nm) showed enhanced antibacterial activity compared to quasi-round agglomerated particles (average size of 442.8±12 nm), regardless of Vo presence or absence.     

Effect of high-pressure homogenisation on metabolic potential of Lacticaseibacillus paracasei 90: in vitro and in situ studies in fermented milk and semihard cheese

The influence of high-pressure homogenisation (HPH) at 100 MPa on Lacticaseibacillus paracasei 90 (L90) was studied in vitro and in situ (fermented milk and cheese). Lysis and injury signs were observed in cells treated with HPH, which were linked to the release of intracellular enzymes and changes in the metabolic activity of L90. HPH treatment led to a higher lactic acid content and lower pH and pyruvic acid levels in fermented milk. The microbiological and peptide profiles of cheeses were modified by using cells or cell-free extracts of L90. Finally, this study suggests that L90 could release bioactive peptides.     

Validation of a Gas Chromatography-Mass Spectrometry Method for the Measurement of the Redox State Metabolic Ratios Lactate/Pyruvate and β-Hydroxybutyrate/Acetoacetate in Biological Samples

The metabolic ratios lactate/pyruvate and β-hydroxybutyrate/acetoacetate are considered valuable tools to evaluate the in vivo redox cellular state by estimating the free NAD+/NADH in cytoplasm and mitochondria, respectively. The aim of the current study was to validate a gas-chromatography mass spectrometry method for simultaneous determination of the four metabolites in plasma and liver tissue. The procedure included an o-phenylenediamine microwave-assisted derivatization, followed by liquid-liquid extraction with ethyl acetate and silylation with bis(trimethylsilyl)trifluoroacetamide:trimethylchlorosilane 99:1. The calibration curves presented acceptable linearity, with a limit of quantification of 0.001 mM for pyruvate, β-hydroxybutyrate and acetoacetate and of 0.01 mM for lactate. The intra-day and inter-day accuracy and precision were within the European Medicines Agency’s Guideline specifications. No significant differences were observed in the slope coefficient of three-point standard metabolite-spiked curves in plasma or liver and water, and acceptable recoveries were obtained in the metabolite-spiked samples. Applicability of the method was tested in precision-cut liver rat slices and also in HepG2 cells incubated under different experimental conditions challenging the redox state. In conclusion, the validated method presented good sensitivity, specificity and reproducibility in the quantification of lactate/pyruvate and β-hydroxybutyrate/acetate metabolites and may be useful in the evaluation of in vivo redox states.     

Core–shell polypyrrole nanoparticles obtained by atmospheric pressure plasma polymerization

Polypyrrole hollow nanoparticles were prepared by atmospheric pressure plasma polymerization. The structure of the nanoparticles was studied using Fourier transform infrared and X‐ray photoelectron spectroscopies, thermogravimetric analysis, scanning and transmission electron microscopies and atomic force microscopy. In contrast to low‐pressure plasma polymerization of pyrrole, which can produce films and solid nanoparticles, we obtained two types of hollow nanoparticles: a fraction with single spherical core and another with a core composed of small bubbles. Thermal characterization allowed us to determine that the nanoparticles are composed of highly crosslinked polymer. A mechanism that explains the formation of both types of hollow nanoparticles as well as solid nanoparticles is proposed. Chemical characterization shows that, in addition to the expected chemical structures due to pyrrole polymerization, the high energy of the plasma at atmospheric pressure produces intense dehydrogenation and oxidation processes. The fluorescence spectrum of the nanoparticles, however, shows a peak at 482 nm indicating that some degree of π‐conjugation is present in the material. © 2014 Society of Chemical Industry     

Observable effects of Ca2+ buffers on local Ca2+ signals

Calcium signals participate in a large variety of physiological processes. In many instances, they involve calcium entry through inositol 1,4,5-trisphosphate (IP(3)) receptors (IP(3)Rs), which are usually organized in clusters. Recent high-resolution optical experiments by Smith & Parker have provided new information on Ca(2+) release from clustered IP(3)Rs. In the present paper, we use the model recently introduced by Solovey & Ponce Dawson to determine how the distribution of the number of IP(3)Rs that become open during a localized release event may change by the presence of Ca(2+) buffers, substances that react with Ca(2+), altering its concentration and transport properties. We then discuss how buffer properties could be extracted from the observation of local signals.