Kinetics and hydrogen storage performance of Li-Mg-N-H systems doped with Al and AlCl3

Recent investigations showed the formation of new amide-chloride phases between LiNH2 and AlCl3 after milling and/or heating under hydrogen pressure. These phases exhibited a key role in the improvement of the hydrogen storage properties of the LiNH2-LiH composite. In the present work, we studied the effects of Al and AlCl3 additives on the hydrogen storage behavior of the Li-Mg-N-H system. The dehydrogenation kinetics and the reaction pathway of Al and AlCl3 modified LiNH2-MgH2 composite were investigated through a combination of kinetic measurements and structural analyses. During the first cycle, the addition of Al catalytically accelerates the hydrogen release at 200 °C. In the subsequent cycles, the formation of a new phase of unknown nature is probably responsible for both increased equilibrium hydrogen pressure and decreased dehydrogenation rate. In contrast, AlCl3 additive reacts with LiNH2-MgH2 through the milling and continues during heating under hydrogen pressure. Addition of AlCl3 leads to the formation of two cubic structures identified in the Li-Al-N-H-Cl system, which improves dehydrogenation rate by modifying the thermodynamic stability of the material. This study evidences positive effect of cation and/or anion substitution on hydrogen storage properties of the Li-Mg-N-H system.This study has been partially supported by bilateral collaboration Project MINCyT-MA

Determining the Orientation of Protegrin-1 in DLPC Bilayers Using an Implicit Solvent-Membrane Model

Continuum models that describe the effects of solvent and biological membrane molecules on the structure and behavior of antimicrobial peptides, holds a promise to improve our understanding of the mechanisms of antimicrobial action of these peptides. In such methods, a lipid bilayer model membrane is implicitly represented by multiple layers of relatively low dielectric constant embedded in a high dielectric aqueous solvent, while an antimicrobial peptide is accounted for by a dielectric cavity with fixed partial charge at the center of each one of its atoms. In the present work, we investigate the ability of continuum approaches to predict the most probable orientation of the β-hairpin antimicrobial peptide Protegrin-1 (PG-1) in DLPC lipid bilayers by calculating the difference in the transfer free energy from an aqueous environment to a membrane-water environment for multiple orientations. The transfer free energy is computed as a sum of two terms; polar/electrostatic and non-polar. They both include energetic and entropic contributions to the free energy. We numerically solve the Poisson-Boltzmann equation to calculate the electrostatic contribution to the transfer free energy, while the non-polar contribution to the free energy is approximated using a linear solvent accessible surface area relationships. The most probable orientation of PG-1 is that with the lowest relative transfer free energy. Our simulation results indicate that PG-1 assumes an oblique orientation in DLPC lipid bilayers. The predicted most favorable orientation was with a tilt angle of 19°, which is in qualitative agreement with the experimentally observed orientations derived from solid-state NMR data

Robust estimation of bacterial cell count from optical density

Optical density (OD) is widely used to estimate the density of cells in liquid culture, but cannot be compared between instruments without a standardized calibration protocol and is challenging to relate to actual cell count. We address this with an interlaboratory study comparing three simple, low-cost, and highly accessible OD calibration protocols across 244 laboratories, applied to eight strains of constitutive GFP-expressing E. coli. Based on our results, we recommend calibrating OD to estimated cell count using serial dilution of silica microspheres, which produces highly precise calibration (95.5% of residuals <1.2-fold), is easily assessed for quality control, also assesses instrument effective linear range, and can be combined with fluorescence calibration to obtain units of Molecules of Equivalent Fluorescein (MEFL) per cell, allowing direct comparison and data fusion with flow cytometry measurements: in our study, fluorescence per cell measurements showed only a 1.07-fold mean difference between plate reader and flow cytometry data

Variation of Used Vegetable Oils’ Composition upon Treatment with Algerian Clays

The treatment of used vegetable oils (UVOs) with clays represents a pivotal step in their industrial recycling process as well as one of the most challenging topics for researchers. In particular, cheap, effective, and sustainable powders need to be explored in order to develop new processes which produce beneficial results in relation to economic and environmental aspects. In this context, five samples within commercial and waste vegetable oils were treated with two sodium- and calcium-based bentonites employing a low oil/bentonite ratio (0.15 wt%). The outcomes of the processes were monitored by FT-IR spectroscopy and compared with the data relative to the parent commercial edible oil. In particular, treatment of FT-IR data by multivariate statistical analysis allowed us to determine a chemical fingerprint characteristic of each sample. Important relationships between the overall chemical composition and the specific clay employed and the treatment time (2 or 4 h) were highlighted. Finally, N2 physisorption, TEM microscopy, and FT-IR analyses of the more efficient Na bentonite allowed us to characterize the material and thus to furnish all the information needed to set-up a general protocol for the partial regeneration of waste vegetable oil destined for further processing

A mechanochemical route for the synthesis of VNbO5VNbO_{5} and its structural re-investigation using structure solution from powder diffraction data

A new and solvent-free synthesis route has been adopted and optimized to prepare crystalline VNbO5 from the mechanochemical reaction between Nb2O5 and V2O5 as starting reagents. The substantially amorphous mixture of equimolar pentoxide V and Nb metals observed after extended mechanical treatment transforms into a crystalline powder following calcination under mild conditions at 710 K. The structure solution of the X-ray diffraction pattern using a global optimization approach, combined with Rietveld refinement, points to a space group P212121 (no. 19) different from Pnma (no. 62) previously proposed in the literature assuming it to be isostructural to VTaO5. The new space group helps to describe weak peaks that remained previously unaccounted for and allows more reliable determination of atomic fractional coordinates and interatomic distance distribution. The as-prepared VNbO5 has been tested as a dopant (5 wt%) for the purpose of solid state hydrogen storage, decreasing significantly the release of hydrogen of MgH2/Mg (620 K) and further enhancing the hydrogen sorption kinetic properties

Intranasal Delivery of Genistein-Loaded Nanoparticles as a Potential Preventive System against Neurodegenerative Disorders

Genistein has been reported to have antioxidant and neuroprotective activity. Despite encouraging in vitro and in vivo results, several disadvantages such as poor water solubility, rapid metabolism, and low oral bioavailability limit the clinical application of genistein. The aim of this study was to design and characterize genistein-loaded chitosan nanoparticles for intranasal drug delivery, prepared by the ionic gelation technique by using sodium hexametaphosphate. Nanoparticles were characterized in vitro and their cytotoxicity was tested on PC12 cells. Genistein-loaded nanoparticles were prepared, and sodium hexametaphosphate was used as a valid alternative to well-known cross-linkers. Nanoparticle characteristics as well as their physical stability were affected by formulation composition and manufacturing. Small (mean diameters of 200–300 nm) and homogeneous nanoparticles were obtained and were able to improve genistein penetration through the nasal mucosa as compared to pure genistein. Nanoparticle dispersions showed a pH consistent with the nasal fluid and preserved PC12 cell vitality

Design of Amperometric Biosensors for the Detection of Glucose Prepared by Immobilization of Glucose Oxidase on Conducting (Poly)Thiophene Films

Enzyme-based sensors have emerged as important analytical tools with application in diverse fields, and biosensors for the detection of glucose using the enzyme glucose oxidase have been widely investigated. In this work, the preparation of biosensors by electrochemical polymerization of (poly)thiophenes, namely 2,2′-bithiophene (2,2′-BT) and 4,4′-bis(2-methyl-3-butyn-2-ol)-2,2′-bithiophene (4,4′-bBT), followed by immobilization of glucose oxidase on the films, is described. N-cyclohexyl-N′-(2-morpholinoethyl)carbodiimide metho-p-toluenesulfonate (CMC) was used as a condensing agent, and p-benzoquinone (BQ) was used as a redox mediator in solution. The glucose oxidase electrodes with films of 2,2′-BT and 4,4′-bBT were then tested for their ability in detecting glucose from synthetic and real samples (pear, apricot, and peach fruit juices)

Graphene Oxide/Iron Oxide Nanocomposites for Water Remediation

Graphene oxide/iron (III–VI) oxides nanocomposites have been produced with a fast and one-pot synthesis. K2FeO4 (Fe(VI)-based compound), obtained from a dry synthesis, has been used as a green oxidant of graphite to produce graphene oxide, avoiding the use of the toxic permanganates. Graphene oxide flakes with a low oxidation degree and decorated with iron oxide have been obtained in one-step reaction. The material has been characterized by several techniques to investigate the structure (SEM, TEM analysis), the composition (X-ray fluorescence, XPS, FTIR, UV–visible, fluorescence, and Raman spectroscopy) and the performance (HPLC). The combined use of ferrate and graphene oxide/iron oxide is an efficient, cheap, and green alternative for water remediation. Real water samples containing different types of emerging pollutants (organic dyes, pesticides, and pharmaceutical drugs) have been efficiently decontaminated obtaining an abatement of 99% in a few minutes. The nanocomposite is paramagnetic and can be easily removed from water with a magnet after depollution. The materials have shown one of the best decontamination performance reported in the scientific literature so far