Optimisation of pressurised liquid extraction for the ultra-trace quantification of 20 priority substances from the European Water Framework Directive in atmospheric particles by GC-MS and LC-FLD-MS/MS

Atmospheric deposition plays an important role in environmental pollution and human health. However, very few information is available on the presence, in atmospheric particles, of organic priority substances in contrast to inorganic fraction. A method for the extraction and quantification of 20 priority organic substances listed in the European Water Framework Directive in atmospheric particles was developed. This method consists in a combination of gas chromatography coupled with mass spectrometry and ultra-high-pressure liquid chromatography coupled with tandem mass spectrometry and fluorescence. Optimized pressurized liquid extraction using a hexane/dichloromethane/isopropanol mixture was used as extraction procedure from atmospheric particulate matter. The influence of several extraction experimental factors related to the PLE was investigated. The optimized extraction method (80°C, 40 bar, 10 min, 1 cycle) exhibited average recoveries of target analytes higher than 62%. The method detection limits (MDL) were between 0.3 ng g(-1) and 83 ng g(-1). This extraction method, combined with sensitive analytical techniques, leads to satisfactory reliability, sensitivity, and accuracy. The method was applied to real samples, collected from two urban sites by an atmospheric sampling prototype developed in this study. The first results reveal a systematic presence of PAHs at high levels (ranging from 500 ng g(-1) to 10 μg g(-1)) and a variable and lower presence of pesticides at concentrations below 50 ng g(-1) in the samples.     

A New Way for Potential Aminophosphonic Acids Precursors

Abstract

New five membered-ring 3,3-dihydro-1,4,2-oxazaphospholenes 1, potential precursors of aminophosphonic acids, have been synthesized and characterized by ¹H, ¹³C and ³¹P NMR.     

A Convenient One-Pot Synthesis of Phosphino-Dipeptide Analogs

A general "one-pot" synthetic method is described for the preparation of phosphinodipeptides of type 1 , in 60-80% overall yield, allowing the variation of the substituents in f and/or g position to the phosphorus atom and also in f position to the nitrogen atom.     

Iα → Iβ transition of cellulose under ultrasonic radiation

Aqueous suspensions of dispersed Glaucocystis cellulose microfibrils were sonicated at 4 °C for 3 h, using 24 kHz ultrasonic waves. This treatment induced a variety of ultrastructural defects, as the microfibrils became not only shortened, but also presented substantial damage materialized by kinks and subfibrillation. Upon analysis by X-ray diffraction and ¹³C solid-state NMR spectroscopy, it was found that the initial sample that contained 90 % of cellulose I_α allomorph became, to a large extent, unexpectedly converted into the I_β phase, while the loss of crystallinity was only moderate during the sonication treatment.     

Entropy viscosity method for nonlinear conservation laws

A new class of high-order numerical methods for approximating nonlinear conservation laws is described (entropy viscosity method). The novelty is that a nonlinear viscosity based on the local size of an entropy production is added to the numerical discretization at hand. This new approach does not use any flux or slope limiters, applies to equations or systems supplemented with one or more entropy inequalities and does not depend on the mesh type and polynomial approximation. Various benchmark problems are solved with finite elements, spectral elements and Fourier series to illustrate the capability of the proposed method.     

Light funneling mechanism explained by magnetoelectric interference

We investigate the mechanisms involved in the funneling of optical energy into subwavelength grooves etched on a metallic surface. The key phenomenon is unveiled thanks to the decomposition of the electromagnetic field into its propagative and evanescent parts. We unambiguously show that the funneling is not due to plasmonic waves flowing toward the grooves, but rather to the magnetoelectric interference of the incident wave with the evanescent field, this field being mainly due to the resonant wave escaping from the groove.     

Steric control of the donor/acceptor interface: implications in organic photovoltaic charge generation

The performance of organic photovoltaic (OPV) devices is currently limited by modest short-circuit current densities. Approaches toward improving this output parameter may provide new avenues to advance OPV technologies and the basic science of charge transfer in organic semiconductors. This work highlights how steric control of the charge separation interface can be effectively tuned in OPV devices. By introducing an octylphenyl substituent onto the investigated polymer backbones, the thermally relaxed charge-transfer state, and potentially excited charge-transfer states, can be raised in energy. This decreases the barrier to charge separation and results in increased photocurrent generation. This finding is of particular significance for nonfullerene OPVs, which have many potential advantages such as tunable energy levels and spectral breadth, but are prone to poor exciton separation efficiencies. Computational, spectroscopic, and synthetic methods were combined to develop a structure-property relationship that correlates polymer substituents with charge-transfer state energies and, ultimately, device efficiencies.     

Biological Assessment of the NO-Dependent Endothelial Function

Nitric oxide (NO) is implicated in numerous physiological processes, including vascular homeostasis. Reduced NO bioavailability is a hallmark of endothelial dysfunction, a prequel to many cardiovascular diseases. Biomarkers of an early NO-dependent endothelial dysfunction obtained from routine venous blood sampling would be of great interest but are currently lacking. The direct measurement of circulating NO remains a challenge due by its high reactivity and short half-life. The current techniques measure stable products from the NO signaling pathway or metabolic end products of NO that do not accurately represent its bioavailability and, therefore, endothelial function per se. In this review, we will concentrate on an original technique of low temperature electron paramagnetic resonance spectroscopy capable to directly measure the 5-α-coordinated heme nitrosyl-hemoglobin in the T (tense) state (5-α-nitrosyl-hemoglobin or HbNO) obtained from fresh venous human erythrocytes. In humans, HbNO reflects the bioavailability of NO formed in the vasculature from vascular endothelial NOS or exogenous NO donors with minor contribution from erythrocyte NOS. The HbNO signal is directly correlated with the vascular endothelial function and inversely correlated with vascular oxidative stress. Pilot studies support the validity of HbNO measurements both for the detection of endothelial dysfunction in asymptomatic subjects and for the monitoring of such dysfunction in patients with known cardiovascular disease. The impact of therapies or the severity of diseases such as COVID-19 infection involving the endothelium could also be monitored and their incumbent risk of complications better predicted through serial measurements of HbNO.     

Surface Assisted Nucleation and Growth of Polymer Latexes on Organically-Modified Inorganic Particles

Summary: Polymer latex particles were synthesized in the presence of inorganic particles, which had been organically-modified to promote favorable interactions with growing macromolecules. The organic modification was performed using three different routes: (1) surface covalent grafting of vinyl trialkoxysilanes, (2) surface adsorption of polyethylene glycol-based macromonomers, and (3) bulk modification through ion exchange with cationic monomers or cationic initiators. Two types of mineral particles were studied: commercial and self-prepared silica particles (with diameters from 80 nm to 1 µm), and commercial laponite clay particles with a cation exchange capacity of 0.75 meq · g⁻¹. Emulsion polymerization was performed in the presence of styrene or butyl acrylate monomers. The morphologies of the nanocomposite particles were observed by (cryogenic) transmission electron microscopy and correlated to the organic modification procedure.     

Markov quantum semigroups admit covariant MarkovC*-dilations

Through a Daniell-Kolmogorov type construction, to any Markov quantum semigroup on aC*-algebra there is associated a quantum stochastic process which is a dilation of the semigroup, and satisfies a covariance rule which implies the weak Markov property.