Determination of Set-Membership Identifiability Sets

This paper concerns the concept of set-membership identifiability introduced in Jauberthie et al. (Proceedings of the 18th IFAC World Congress. Milan, Italie, 12024–12029, 2011). Given a model, a set-membership identifiable set is a connected set in the parameter domain of the model such that its corresponding trajectories are distinct to trajectories arising from its complementary. For obtaining the so-called set-membership identifiable sets, we propose an algorithm based on interval analysis tools. The proposed algorithm is decomposed into three parts namely mincing, evaluating and regularization (Jaulin et al. in Applied interval analysis, with examples in parameter and state estimation, robust control and robotics. Springer, Londres, 2001). The latter step has been modified in order to obtain guaranteed set-membership identifiable sets. Our algorithm will be tested on two examples.     

Comparative study of microwave-induced plasma atomic emission spectrometry and atomic fluorescence spectrometry as gas-chromatographic detectors for the determination of methylmercury in biological samples

In order to attain a lower detection limit with the HS GC MIP analytical method (Head-Space Gas Chromatography with Microwave-Induced Plasma detection) recently developed for the analysis of methylmercury in biological samples, the quarter-wave Evenson-type cavity used until now was replaced by a TM₀₁₀ Beenakker-type cavity, which was used with both argon and helium as carrier gas. With an argon plasma, an eightfold increase in detection limit was gained compared with the argon plasma sustained by the Evenson cavity, while only a four-fold increase was gained with the helium plasma. In a second step of the study, the MIP detector was replaced by an AFS (atomic fluorescence) detector (CVAFS Model-2, Brooks Rand Ltd, Seattle, USA). With this AFS detector a detection limit of 1 ng methyl mercury per g biological tissue could be reached; i.e. measurements were 40 times more sensitive than those using the Evenson cavity. This detector has some other advantages compared with MIP detection: it is less expensive and easier to manipulate, while the same precision and accuracy are obtained. The use of AFS as detector in the headspace gas chromatographic system is therefore an important improvement for the analysis of methyl-mercury in biological samples.     

The first 3-D ferrimagnetic nickel fumarate with an open framework: [Ni3(OH)2(O2C-C2H2-CO2)(H2O)4].2H2O

A three-dimensional nickel fumarate has been isolated by hydrothermal reaction and its structure solved from powder X-ray diffraction; its organisation reveals an unusual topology not previously seen in nickel chemistry and provided a scarce ferrimagnetic behaviour below 20 K.     

Hexacyanometalate molecular chemistry: heptanuclear heterobimetallic complexes; control of the ground spin state

Following a bottom-up approach to nanomaterials, we present a rational synthetic route from hexacyanometalates [M(CN)(6)](3-) (M=Cr(III), Co(III)) cores to well-defined heptanuclear complexes. By changing the nature of the metallic cations and using a localised orbital model it is possible to control and to tune the ground state spin value. Thus, with M=Cr(III), d(3), S=3/2, three heptanuclear species were built and characterised by mass spectrometry in solution, by single-crystal X-ray diffraction and by powder magnetic susceptibility measurements, [Cr(III)(CNbondM'L(n))(6)](9+) (M'=Cu(II), Ni(II), Mn(II), L(n)=polydentate ligand), showing spin ground states S(G)=9/2 [Cu(II)], with ferromagnetic interactions J(Cr,Cu)=+45 cm(-1), S(G)=15/2 [Ni(II)] and J(Cr,Ni)=+17.3 cm(-1), S(G)=27/2 [Mn(II)], with an antiferromagnetic interaction J(Cr,Mn)=-9 cm(-1), (interaction Hamiltonian H=-J(Cr,M) [S(Cr)Sigma(i)S(M)(i)], i=1-6). With M=Co(III), d(6), S=0, the heptanuclear analogues [Co(III)(CN-M'L(n))(6)](9+) (M'=Cu(II), Ni(II), Mn(II)) were similarly synthesised and studied. They present a singlet ground state and allow us to evaluate the weak antiferromagnetic coupling constant between two next-nearest neighbours M'-Co-M'.     

Simultaneous measurement of the maximum oscillation amplitude and the transient decay time constant of the QCM reveals stiffness changes of the adlayer

Interpretation of adsorption kinetics measured with a quartz crystal microbalance (QCM) can be difficult for adlayers undergoing modification of their mechanical properties. We have studied the behavior of the oscillation amplitude, A₀, and the decay time constant, , of quartz during adsorption of proteins and cells, by use of a home-made QCM. We are able to measure simultaneously the frequency, f, the dissipation factor, D, the maximum amplitude, A₀, and the transient decay time constant, , every 300 ms in liquid, gaseous, or vacuum environments. This analysis enables adsorption and modification of liquid/mass properties to be distinguished. Moreover the surface coverage and the stiffness of the adlayer can be estimated. These improvements promise to increase the appeal of QCM methodology for any applications measuring intimate contact of a dynamic material with a solid surface.     

Carbo‐biphenyls and Carbo‐terphenyls: Oligo(phenylene ethynylene) Ring Carbo‐mers

Ring carbo‐mers of oligo(phenylene ethynylene)s (OPEn, n=0–2), made of C₂‐catenated C₁₈ carbo‐benzene rings, have been synthesized and characterized by NMR and UV‐vis spectroscopy, crystallography and voltammetry. Analyses of crystal and DFT‐optimized structures show that the C₁₈ rings preserve their individual aromatic character according to structural and magnetic criteria (NICS indices). Carbo‐terphenyls (n=2) are reversibly reduced at ca. ?0.42 V/SCE, i.e. 0.41 V more readily than the corresponding carbo‐benzene (?0.83 V/SCE), thus revealing efficient inter‐ring π‐conjugation. An accurate linear fit of E_1/2^red1 vs. the DFT LUMO energy suggests a notably higher value (?0.30 V/SCE) for a carbo‐quaterphenyl congener (n=3). Increase with n of the effective π‐conjugation is also evidenced by a red shift of two of the three main visible light absorption bands, all being assigned to TDDFT‐calculated excited states, one of them restricting to a HOMO→LUMO main one‐electron transition.     

Determination of methylmercury in natural waters by headspace gas chromatography with microwave-induced plasma detection after preconcentration on a resin containing dithiocarbamate groups

A method for the determination of methylmercury at ng l^?1 levels in natural waters is described. Methylmercury present in a sample is first preconcentrated on a column of a resin containing dithiocarbamate groups and eluted quantitatively with acidic thiourea solution. Methylmercury in the effluent is then converted to the iodide by addition of sulphuric acid and iodoacetic acid and determined by headspace gas chromatography with microwave-induced plasma detection. The adsorption properties of the resin are discussed.     

Syntheses of β‐C(1→3)‐Glucopyranosides of 2‐ and 4‐Deoxy‐D‐hexoses

The Oshima? Nozaki (Et₂AlI) condensation of isolevoglucosenone ( 4 ) with 2,6‐anhydro‐3,4,5,7‐tetra‐O‐benzyl‐D ‐glycero‐D ‐gulo‐heptose ( 5 ) gave an enone 6 that was converted with high stereoselectivity to 3‐C‐[(1R)‐2,6‐anhydro‐D ‐glycero‐D ‐gulo‐heptitol‐1‐C‐yl]‐2,3‐dideoxy‐D ‐arabino‐hexose ( 1 ; 1 : 1 mixture of α‐ and β‐D ‐pyranose), and to 3‐C‐[(1R)‐2,6‐anhydro‐D ‐glycero‐D ‐gulo‐heptitol‐1‐C‐yl]‐2,3‐dideoxy‐D ‐lyxo‐hexose ( 2 ; 2.7 : 1.4 : 1.0 : 1.4 mixture of α‐D ‐furanose, β‐D ‐furanose, α‐D ‐pyranose, and β‐D ‐pyranose). The Oshima? Nozaki (Et₂AlI) condensation of levoglucosenone ( 17 ) with aldehyde 5 gave an enone 18 that was converted with high stereoselectivity to 3‐C‐[(1R)‐2,6‐anhydro‐D ‐glycero‐D ‐gulo‐heptitol‐1‐C‐yl]‐3,4‐dideoxy‐α‐D ‐arabino‐hexopyranose ( 3 ; single anomer).     

Exploring structural effects of levoglucosenone derived chiral auxiliaries in asymmetric Diels-Alder cycloadditions

New chiral auxiliaries derived from levoglucosenone were developed in a simple and efficient way and evaluated as chiral inductors in asymmetric Diels-Alder reactions between the corresponding acrylate derivatives and cyclopentadiene. The results showed an important influence of the absolute configuration of the C(2) center of the auxiliary on the level of stereoinduction obtained.