Chemical stability of midazolam injection by high performance liquid chromatography

The chemical stability of midazolam hydrochloride injection, undiluted or diluted with dextrose sterile solution, was studied at different storage conditions by LC. The study was performed at room temperature (23 +/- 2 degrees C) under light exposure and light protection, +8 +/- 1 degrees C and -20 +/- 0.5 degrees C, in glass and plastic containers over 14 days with midazolam hydrochloride injection, undiluted or diluted with 5% dextrose sterile solution. Chromatographic separation was carried out on a RP-18(e) column, using a mobile phase consisting of ACN-phosphate buffer (pH 3.3; 0.1 M) (30:70 v/v) at a flow rate of 1.0 mL/min and UV detection at 220 nm. The concentrations of all samples remained greater than 90% of the original concentration. The chromatographic assay exhibited an adequate linearity (r(2) >0.999), selectivity, precision (RSD <3.1), and accuracy (recoveries from 100.46 to 101.40%). Injectable midazolam hydrochloride was chemically stable in all conditions that were studied.     

Multimodal Biomedical Implant with Plasmonic and Simulated Body Temperature Responses

This work presents a novel nanoparticle-based thermosensor implant able to reveal the precise temperature variations along the polymer filaments, as it contracts and expands due to changes in the macroscale local temperature. The multimodal device is able to trace the position and the temperature of a polypropylene mesh, employed in abdominal hernia repair, by combining plasmon resonance and Raman spectroscopy with hydrogel responsive system. The novelty relies on the attachment of the biocompatible nanoparticles, based on gold stabilized by a chitosan-shell, already charged with the Raman reporter (RaR) molecules, to the robust prosthesis, without the need of chemical linkers. The SERS enhanced effect observed is potentiated by the presence of a quite thick layer of the copolymer (poly(N-isopropylacrylamide)-co-poly(acrylamide)) hydrogel. At temperatures above the LCST of PNIPAAm-co-PAAm, the water molecules are expulsed and the hydrogel layer contracts, leaving the RaR molecules more accessible to the Raman source. In vitro studies with fibroblast cells reveal that the functionalized surgical mesh is biocompatible and no toxic substances are leached in the medium. The mesh sensor opens new frontiers to semi-invasive diagnosis and infection prevention in hernia repair by using SERS spectroscopy. It also offers new possibilities to the functionalization of other healthcare products.     

Views of cognition: different lenses for ‘looking-in’ on classrooms

The evolution of different theories of cognition over the years has given mathematics education researchers new tools for highlighting particular characteristics of classroom issues to enable more detailed investigation of how students learn mathematics. In the past there has been a strong dominance of the dualistic view separating body and mind. In recent times, however, the body has been given a more central role in shaping the mind. This has led to the situation where some long-standing conundrums of mathematics education have become more tractable to researchers. Similarly, using older ideas in new ways, light is being shone on what is possible at different stages of development or different levels of schooling. In this issue different views of cognition have been mined by the authors of different articles to frame studies and analyses or invent and apply new tools. They bring new lenses for looking-in on classrooms, a fresh view with old lenses and new methodological tools to the fore. Using a small selection of the articles of the issue the empowerment that differing views of cognition have enabled for mathematics education research is demonstrated.     

Activation by Glutathione in Hypoxic Environment of an Azo-based Rhodamine Activatable Photosensitizer. A Computational Elucidation

In the present paper, density functional theory (DFT) has been applied to the study of the activation mechanism of a new selenium azo-rhodamine (azoSeRho) in presence of the tripeptide thiol, glutathione (GSH), as potent activatable photosensitizer to be employed in photodynamic therapy. The introduction of the azo group into the conjugated system of the seleno-rhodamine dye and its reaction with GSH allow the selective formation of the active photosensitizer, SeRho. Furthermore, DFT calculations have allowed to shed light on the activation mechanism of the azoSeRho photosensitizer when molecular oxygen is present and hydrogen peroxide is formed. This study is the first theoretical investigation revealing how the reductive cleavage of the azo moiety by GSH occurs. Time-dependent DFT approach has been used to evaluate the chalcogen-substitution effect on the structures and photophysical properties of the azo derivatives and, then, on the activated photosensitizers.     

EPMA Major and Trace Element Analysis in Garnet and its Petrological Application

 A comparison between major and trace element concentrations in garnet performed by electron microprobe (EPMA) technique is reported. Quantitative spot analyses and X-ray maps of major elements (Fe, Mg, Mn, Ca) and the trace element yttrium in garnets from metamorphic rocks are presented. The selected garnet samples come from meta-pelitic and meta-basic specimens belonging to the tectonic unit of the Monte Rosa Nappe (Western Alps). In the metapelites, the quantitative Y distribution maps display a prominent increase at the core, the Y abundance varying by over two orders of magnitude, from about 80 ppm (rim) to over 2100 ppm (core). The Y profiles show well defined patterns with sharp features that do not correlate with major element distributions. A roughly comparable pattern can be supposed only with Mn. The Y distribution suggests that the diffusion of Y through the garnet is very slow compared to the major elements, thus the Y results are suitable for geothermometric estimates. In the metabasites, the Y spatial distribution is characterised by an increasing content from the core to the rim, displaying a zoning pattern opposite to the metapelite garnet. Quantitative EPMA analyses range from 1100 ppm at the rim to values lower than the detection limit at the core. Therefore, the Y content in the garnet can be related to several chemical and physical variables such as the bulk rock composition and the phase assemblage. In particular, in the xenotime-bearing metapelitic system the Y distribution seems to be correlated with metamorphic peak temperature.     

Surface characterization of a decarburized and nitrided steel.

This article describes the effects of surface controlled decarburization on the structure of a nitrided steel. Samples of quenched and tempered 40CrMo4 steel were decarburized by air heat treatment (800-900 degrees C) at different depths and submitted to gaseous nitriding. The microstructure of surface layers after decarburization and nitriding were investigated by optical (OM) and scanning electron microscopy (SEM). The nitrogen and carbon profiles in the diffusion layers were determined by a scanning electron microscope equipped with a wavelength dispersive spectrometer (EPMA-WDS). The effect of nitriding was determined by microhardness measurements. The increasing of time and temperature of decarburization slightly affect the surface hardness values, while case hardness depths decrease. In all the specimens, the nitriding depth, as determined by the WDS nitrogen profile, is larger than the one determined by the hardness profile.     

A tail-revisited Markowitz mean-variance approach and a portfolio network centrality

A measure for portfolio risk management is proposed by extending the Markowitz mean-variance approach to include the left-hand tail effects of asset returns. Two risk dimensions are captured: asset covariance risk along risk in left-hand tail similarity and volatility. The key ingredient is an informative set on the left-hand tail distributions of asset returns obtained by an adaptive clustering procedure. This set allows a left tail similarity and left tail volatility to be defined, thereby providing a definition for the left-tail-covariance-like matrix. The convex combination of the two covariance matrices generates a “two-dimensional” risk that, when applied to portfolio selection, provides a measure of its systemic vulnerability due to the asset centrality. This is done by simply associating a suitable node-weighted network with the portfolio. Higher values of this risk indicate an asset allocation suffering from too much exposure to volatile assets whose return dynamics behave too similarly in left-hand tail distributions and/or co-movements, as well as being too connected to each other. Minimizing these combined risks reduces losses and increases profits, with a low variability in the profit and loss distribution. The portfolio selection compares favorably with some competing approaches. An empirical analysis is made using exchange traded fund prices over the period January 2006–February 2018.

     

Thermodynamics of ice at high pressures and low temperatures

A new equation of state of ice Ih recently proposed by Feistel and Wagner [J. Phys. Chem. Ref. Data 35 (2006) 1021-1047] is used to study the phenomena related to the equilibrium isentropic compression of an ice-water mixture and dynamic loading of solid ice. New results are presented concerning the properties of the new equation of state, equilibrium solid-liquid phase transitions and Hugoniots of low-temperature (100 K) and temperate (263 K) shock-compressed ice.