Groupes Moyennables, Dimension Topologique Moyenne et sous-décalages

Let G be an infinite countable residually finite amenable group. In this paper we construct a continuous action of G on a compact metrisable space X such that the dynamical system (X, G) cannot be embedded in the G-shift on [0,1] ^G . This result generalizes a construction due to E. Lindenstrauss and B. Weiss (Mean topological dimension, Israel J. Math. 115 (2000), 1–24) for .     

Fast production of highly concentrated reactive [F] fluoride for aliphatic and aromatic nucleophilic radiolabelling

The use of a polymeric solid support loaded with a long alkyl chain quaternary ammonium allows the rapid and efficient recovery of cyclotron produced [¹⁸F]F⁻ from [¹⁸O]water to a low water content organic solution compatible with fast nucleophilic labelling of most precursors for PET radiopharmaceuticals in high yield.     

Minimal systems of arbitrary large mean topological dimension

Let G be a countable amenable group and P a polyhedron. The mean topological dimension mdim(X,G) of a subshift X ⊂ P ^G is a real number satisfying 0 ≤ mdim(X,G) ≤ dim(P), where dim(P) denotes the usual topological dimension of P. We give a construction of minimal subshifts X ⊂ P ^G with mean topological dimension arbitrarily close to dim(P).     

The Jacobian, the square root and the set ∞

In these notes, we wish to present a new approach to the problem of prescribing Jacobian determinants in dimension two: we restrict ourselves to the case the datum is a finite sum of Dirac masses. The main point is to show that we may relate this problem to the search of harmonic maps into a singular space shaped as the symbol ∞. The later problem in turn is closely linked to questions in complex analysis. A large part of the paper is devoted to a presentation of these mathematical objects and their connections.     

Anisotropic 1H STD-NMR Spectroscopy: Exploration of Enantiomer-Polypeptide Interactions in Chiral Oriented Environments

The front cover artwork is provided by Dr. Philippe Lesot's group (NMR in Oriented Media, ICMMO, UMR CNRS 8182) at Université Paris-Saclay, France. The image shows four pieces of a puzzle: the magnet of an NMR spectrometer, the principle of the ¹H STD-NMR experiment and the 3D helical structure of the poly-γ-benzyl-L-glutamate polymer leading to a chiral liquid-crystalline phase that discriminates the enantiomers of a model chiral solute (1-phenethyl alcohol). Putting these pieces of the puzzle together allows us to identify the hydrogen sites of each enantiomer interacting with the polypeptide side chain. These new outcomes are a further step towards a global understanding of the chiral recognition that occurs in such media. Read the full text of the Research Article at 10.1002/cphc.202200508 .     

Sensitive determination of diuron on zinc oxide nanoparticles modified carbon paste electrode in soil and water samples

An electrochemical sensor based on Zinc oxide nanoparticles (ZnONPs) modified carbon paste electrode was designed for the toxic diuron pesticide detection. The ZnONPs were synthesized through the hydrothermal route and their structural properties were investigated via scanning electron microscopy (SEM) and X-ray diffraction powder (XRD). The designed ZnONPs-modified carbon paste electrode (ZnONPs-CPE) was characterized using cyclic voltammetry and electrochemical impedance spectroscopy. The sensor showed significantly enhanced sensitivity on the diuron oxidation peak current, compared to the bare carbon paste electrode. Qualitative and quantitative analysis were performed using cyclic voltammetry (CV) and square wave voltammetry (SWV). Experimental parameters such as pH, amount of ZnONPs and frequency were evaluated and the optimized conditions were obtained with 0.1 M phosphate buffer solution at pH=8, a frequency of 50 Hz and a quantity of 5 mg of ZnONPs. Under these conditions, linear responses ranging from 1.3 to 7.7 μM and 8.6 to 30 μM of diuron were obtained, with correlation coefficients of R²=0.994 and 0.996 respectively. Detection and quantification limits of 0.22 μM and 0.84 μM (S/N=3) were respectively achieved based on the 3σ method. The interference of some ions on the oxidation peak of diuron on ZnONPs-CPE was also evaluated and no interference was observed, therefore demonstrating the selectivity of the sensor. The proposed sensor, designed with ecofriendly materials, is sensitive, selective and was effectively used for diuron determination in soils and water samples with recoveries ranging from 98 % to 101.5 %.     

Polynomial multivariate least‐squares regression for modeling nonlinear data applied to in‐depth characterization of chromatographic resolution

Well‐established, linear multivariate calibration methods such as multivariate least‐squares regression (MLR), principal component regression (PCR), or partial least squares (PLS) have two limitations: (i) measured data must be linearly related to the response variables and (ii) predictor variables x_{n = 1, …, N} cannot be coupled to each other. For evaluation of nonlinear data, however, these restrictions need to be overcome and thus polynomial multivariate least‐squares regression (PMLR or “response surfaces”) has been introduced here. PMLR is based on multivariate least squares but incorporates all combinations of predictor variables up to a user‐selected polynomial order (e.g., including u or v = 0). Because of the inclusion of such coupled terms and their powers, PMLR models are better adapted to model nonlinear data and can help to enhance the prediction step's accuracy and precision. PMLR has been based on MLR because it facilitates—unlike PCR or PLS—a physical and chemical interpretation of the predictors. Hence, the origins and the relevance of nonlinear and/or coupled predictors can be investigated. The details of the PMLR algorithm and its implementation are presented along with a method for model optimization utilizing gradients of response surfaces. Newly developed PMLR models up to quintic order have been applied to predict a chromatograph's peak resolution as a function of six‐instrument parameters. It has been demonstrated that PMLR is better capable than MLR and PCR to describe these nonlinear and coupled instrument parameters. In addition, the novel software tool has been utilized for model optimization to determine instrument parameters, which result in the best chromatographic resolution. Copyright © 2011 John Wiley & Sons, Ltd.     

Alternative Synthesis of 5-(1H-Pyrazol-4-yl)-2-{6-[(2,2,6,6-tetramethylpiperidin-4-yl)oxy]pyridazin-3-yl}phenol

A scalable and environmentally benign route to the free base of branaplam, a small molecule splicing modulator, was identified and developed. This alternative approach circumvented the inherent risk of dioxin formation associated with ortho-halo phenol derivatives present in the previous route. A Friedel–Crafts approach provided a reliable access to the key intermediate, subsequently followed by a Suzuki–Miyaura cross-coupling. Multiple process aspects of the synthetic approach were evaluated, and a robust process for its large-scale synthesis was developed and successfully demonstrated.