Characterization of biomass and biochar by LDI-FTICRMS – Effect of the laser wavelength and biomass material

The pyrolysis of the lignocellulosic biomass is a promising process to produce biofuels or green chemicals. Specific analytical methods have to be developed in order to better understand the composition of biomass and of its pyrolysis products and therefore to optimize the design of pyrolysis processes. For this purpose, different biomasses (Douglas and Miscanthus) and one biochar were analyzed by laser desorption/ionization Fourier transform ion cyclotron resonance mass spectrometry (LDI FT-ICR MS). This method allowed the biomass and biochar to be analyzed without any sample preparation and with a spatial resolution of about 100 μm. The influence of LDI conditions (laser wavelength and laser irradiance) and the nature of the biomass and biochar on the obtained mass spectrum were investigated. The nature and origin of the observed ions highly depended on LDI conditions. In the softest laser–biomass interaction conditions (low laser irradiance), the detected ions were related to the nature of the investigated biomass. Indeed, the main part of the detected species came from the different biomass subunits and was produced by photolysis of covalent bonds. When more severe laser irradiation conditions were used, the obtained mass spectra gathered the ions relative to (i) the chemical components of the investigated samples, (ii) the recombination products of these species in the gas phase after their ejection from the sample surface, and (iii) the compounds produced by laser pyrolysis of the sample. This was expected to be useful to mimic thermal pyrolysis.

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New hybrid membranes based on phosphonic acid functionalized silica particles for PEMFC

This work concerns the development of hybrid organic/inorganic membranes from styrenic phosphonic polymers. The phosphonic charge, composed phosphonic polymers grafted onto silica nanoparticles, was obtained by “grafting onto” method. It consists of synthesizing first the polymer, and then the terminal functions of the latter react with silanol groups of silica. The phosphonated polymer was isolated in two steps, that is, an ATRP polymerization of 4‐chloromethylstyrene followed by Mickaelïs‐Arbusov reaction. After the grafting onto silica, membranes are prepared through formulation containing the charge and the polymer matrix PVDF‐HFP, which are dispersed in DMF. The acid form is obtained by hydrolysis in chlorydric acid. The membrane possessing a 40 wt % charge ratio (IEC = 1.08 meq g^?1) was selected as reference. A proton conductivity of 65 mS cm^?1 at 80 °C was measured in immersed conditions. When the membrane is no more immersed, the value decreases drastically (0.21 mS cm^?1 at 120 °C and 25% RH). © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012     

Dual binding mode of methylmethanetriacetic Acid to tripodal amidopyridine receptors

A series of tripodal amidopyridine receptors capable of selective recognition of methylmethanetriacetic acid (MMTA) in organic solvents is described. Intramolecular hydrogen-bonding groups, built into some of the receptors, were designed as preorganization devices. Binding was studied by NMR titration, variable temperature NMR experiments, 2D-NMR, isothermal titration calorimetry, and single-crystal X-ray crystallography. The results reveal that a balancing act between inter- and intramolecular hydrogen-bonding interactions in the complexes governs both the dynamics and the geometry of binding. Receptor 1b (without intramolecular hydrogen-bonding groups) features a simple symmetric MMTA binding geometry with optimal enthalpic interactions. In sharp contrast, receptor 1a (with intramolecular hydrogen-bonding groups) reveals a temperature-dependent dual binding mode where MMTA can bind in two completely different geometries. The two solution binding geometries of 1a.MMTA were unraveled by NMR experiments and correlated to the X-ray structures.     

OnC *-algebras having linear,polynomial and subexponential growth

Summary Answering a question of Voiculescu [16, Problem 5.9], we show thatC ^*-algebras having filtrations (A _n)_n satisfying the condition lim sup_n ln dimA _n/n=0 (in particular having subexponential growth), are nuclear.For the case of linear growth we obtain the following particular result: letX be a finite dimensional self-adjoint generating system of aC ^*-algebraA such that dim (span (X ⁿ +1))1+dim (span (X ⁿ )), then there exist a finite dimensionalC ^*-algebraC having only irreducible representations of dimension 1 and aC ^*-algebraB, which is generated by a single self-adjoint element, such thatACB.Some other results are given on linear growth and we show that there exist singly generatedC ^*-algebras such that the growth of the filtration (span (X ⁿ ))_n is polynomial, whereX={x,x ^*, 1} is a generating system, and such that in every neighbourhood ofx there exists an invertibley such thatY={1,y,y ^*} is a generating system whose associated filtration (span (Y ⁿ ))_n doesn't satisfy the previous condition of Voiculescu, and in particular does not have subexponential growth.Oblatum 19-X-1991Work partially supported by DFGAllocataire M.R.T., Université Aix-Marseille II (France)     

Line frequency shift measurements by diode-laser spectroscopy for CH(3)D-Xe

The pressure-induced Xe shifting and broadening coefficients for five lines of 12CH(3)D in the nu(3) band near 7.5 microm have been measured using a tunable diode-laser spectrometer. The frequency shift was determined from the simultaneous record of the Xe-broadened line and the same line of pure CH(3)D at low pressure. Comparisons are made with the results of theoretical calculations based on a semiclassical model involving the atom-atom Lennard-Jones (LJ) potential.     

High performance anticorrosive coatings based on new phosphonic methacrylate terpolymers

This article describes the synthesis of new methacrylic‐phosphonated monomer PM(B) obtained from the diethyl‐1,2‐epoxide‐propyl 2‐phosphonate opening by methacrylic acid in presence of the tetrabutyl ammonium bromide as catalyst. Both its homopolymerization and copolymerization with methyl methacrylate (MMA) have been achieved in acetonitrile at 80 °C in the presence of 4,4′‐azobisisobutyronitrile. The determination of the reactivity ratios evidenced a statistical copolymer structure. Then, terpolymer of low degree of polymerization and composed of MMA, butyl methacrylate (BuMA) and PM(B) was synthesized and showed a high thermal stability (no degradation before 300 °C). This phosphonate terpolymer was incorporated in an acrylate formulation, polymerized under UV‐light, and the resulting coating was subjected to the salt spray test. High resistance towards corrosion was observed as no corrosion occurred even after 1100 hrs to the salt spray test. This result was also confirmed by Electrochemical Impedance Spectroscopy. © 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 5090–5100, 2009     

Diode-laser measurements and calculations of N2-broadening coefficients in the ν7 band of ethylene

N₂-broadening coefficients have been measured for 41 lines of C₂H₄ at 173.2 K in the P, Q, and R branches of the ν₇ fundamental band near 10 μm, using a tunable diode-laser spectrometer. These lines were individually fitted with a Voigt and a Rautian profile in order to determine their collisional widths. The resulting broadening coefficients, as well as those previously measured at room temperature for 35 transitions, are compared with values calculated on the basis of a semiclassical model of interacting linear molecules, using an atom-atom Lennard-Jones potential in addition to the electrostatic contributions. An overall satisfactory agreement is obtained for all the results at room and low temperatures. Finally the temperature dependence of the broadening coefficients has been determined through the temperature exponent n, experimentally for the 23 common transitions as well as theoretically for all the studied transitions.