Modelling of the subgrid scale wrinkling factor for large eddy simulation of turbulent premixed combustion

We propose a model for assessing the unresolved wrinkling factor in the large eddy simulation of turbulent premixed combustion. It relies essentially on a power-law dependence of the wrinkling factor on the filter size and an original expression for the ‘active’ corrugating strain rate. The latter is written as the turbulent strain multiplied by an efficiency function that accounts for viscous effects and the kinematic constraint of Peters. This yields functional expressions for the fractal dimension and the inner cut-off length scale, the latter being (i) filter-size independent and (ii) consistent with the Damköhler asymptotic behaviours at both large and small Karlovitz numbers. A new expression for the wrinkling factor that incorporates finite Reynolds number effects is further proposed. Finally, the model is successfully assessed on an experimental filtered database.     

Uncertainty of standard addition experiments: a novel approach to include the uncertainty associated with the standard in the model equation

A new model equation for determining the measurement result in standard addition experiments was derived and successfully applied to the quantitative determination of rhodium in automotive catalysts. Existing equations for standard addition experiments with gravimetric preparation were changed in order to integrate the novel idea of including the uncertainty associated with the standard into the model equation. Using this novel equation combined with the ordinary least squares algorithm for the regression line also yielded a new formula for the associated measurement uncertainty. This uncertainty accounts for the first time for the uncertainty associated with the standard. The derivation for the model equation and the resulting associated measurement uncertainty is shown for gravimetric standard addition experiments both with and without an internal standard.     

A novel chronometry technique for dating irradiated uranium fuels using Cm isotopic ratios

Journal of Radioanalytical and Nuclear Chemistry - A novel chronometry method is developed to date irradiated nuclear fuels. It is based on the measurement of two Cm isotopic ratios (244Cm/246Cm...     

Deciphering the Crystal Structure of a Scarce 1D Polymeric Thorium Peroxo Sulfate

The preparation and structural characterization of an original Th peroxo sulfate dihydrate, crystallizing at room temperature in the form of stable 1D polymeric microfibres is described. A combination of laboratory and synchrotron techniques allowed solution of the structure of the Th(O₂)(SO₄)(H₂O)₂ compound, which crystallizes in a new structure type in the space group Pna2₁ of the orthorhombic crystal system. Particularly, the peroxide ligand coordinates to the Th cations in an unusual μ₃-η²:η²:η² bridging mode, forming an infinite 1D chain decorated with sulfato ligands exhibiting simultaneously monodentate and bidentate coordination modes.     

Diazonium salts for surface‐confined visible light radical photopolymerization

The surface chemistry of aryl diazonium salts has progressed at a remarkable pace in the last two decades, and opened many avenues in materials science. These compounds are excellent coupling agents for polymers to surfaces via several surface‐confined polymerization methods. For the first time, we demonstrate that diazonium salts are efficient for surface initiating radical photopolymerization in the visible light of methyl methacrylate (MMA) and 2‐hydroxyethyl methacrylate (HEMA) taken as model monomers. To do so, 4‐(dimethylamino)benzenediazonium salt was electroreduced on gold plates or flexible ITO sheets to provide 4‐(dimethylamino)phenyl (DMA) hydrogen donor layers; while excited state camphorquinone acted as the free hydrogen abstractor. In the same way, we co‐polymerized HEMA and MMA with ethylene glycol dimethacrylate in order to obtain crosslinked polymer grafts. We demonstrate by XPS that gold was efficiently screened by the polymer layers and that the wettability of the surfaces accounts for the hydrophilic or hydrophobic characters of the tethered polymers. Homo‐ and crosslinked PMMA grafts were found to resist removal by the paint stripper methyl ethyl ketone. The grafted DMA/camphorquinone system operating in the visible light holds great promises in terms of adhesion of in situ designed continuous or patterned polymer coatings on various substrates. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 3506–3515     

Synthesis,characterization, and ion‐complexing properties of polymers displaying densely packed arrays of crown‐ethers as lateral substituents

We report the synthesis and ion‐binding properties of four poly(crown‐ethers) displaying either one or two crown‐ethers (15‐crown‐5 or 18‐crown‐6) on every third carbon alongside the backbone. The polymers were synthesized by living anionic ring‐opening polymerization of disubstituted cyclopropane‐1,1‐dicarboxylates monomers. Cation binding of the polychelating polymers and corresponding monomers to Na⁺ and K⁺ was evaluated by picrate extraction and isothermal calorimetry titration. This novel family of poly(crown‐ethers) demonstrated excellent initial binding of the alkali ions to the polymers, with a higher selectivity for potassium. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 2337–2345     

Convenient Access to Fluorescent Probes by Chemoselective Acylation of Hydrazinopeptides: Application to the Synthesis of the First Far‐Red Ligand for Apelin Receptor Imaging

Herein, we develop a convenient method to facilitate the solution‐phase fluorescent labelling of peptides based on the chemoselective acylation of α‐hydrazinopeptides. This approach combines the advantages of using commercially available amine‐reactive dyes and very mild conditions, which are fully compatible with the chemical sensitivity of the dyes. The usefulness of this approach was demonstrated by the labelling of apelin‐13 peptide. Various fluorescent probes were readily synthesized, enabling the rapid optimization of their affinities for the apelin receptor. Thus, the first far‐red fluorescent ligand with sub‐nanomolar affinity for the apelin receptor was characterized and shown to track the receptor efficiently in living cells by fluorescence confocal microscopy.