Linear relative canonical analysis of Euclidean random variables,asymptotic study and some applications

We introduce the Linear Relative Canonical Analysis (LRCA) of Euclidean random variables. Then similar properties than for usual linear Canonical Analysis are obtained. Furthermore, we develop an asymptotic study of LRCA and apply the obtained results to tests for lack of relative linear association, dimensionality and invariance.     

Etude vibrationnelle du fluorure hydrogenodifluorure de baryum BaF(HF2)

Infrared and Raman spectra of the BaF(HF₂) crystal and its 10 and 50% deuterated derivatives at 300 and 90 K have been investigated in the 4000 to 20 cm⁻¹ range. An assignment of internal and lattice vibrations has been proposed. Vibrational spectra are consistent with a centrosymmetric P2₁/m space group and Z=2. They show that the (FHF)⁻ ion is not centrosymmetrical, in spite of a short F…F distance; a force field calculation has been performed in order to determine the F---H and H…F distances, which are equal to 1.08 and 1.20 Å, respectively, in agreement with the ¹H and ¹⁹F NMR data. The ν₃(H)/ν₃(D) isotope frequency ratio indicates a negative or zero isotope effect on the F…F distance, which is observed for the first time for a strong asymmetric hydrogen bond.     

Raman Study of Aluminum Chloride-Dimethylsulfone Solutions

The Raman spectra of AlCl(3)-LiCl-dimethylsulfone mixtures with different molar compositions have been recorded as a solid (300 K) and as a melt (400 K). In any case, only AlCl(4)(-) ion lines at 120, 179, and 347 cm(-)(1) were observed; we were unable to detect any other chloroaluminate species. Furthermore, some bands assigned to the Al[(CH(3))(2)SO(2)](3)(3+) octahedral coordination compound are evidence for a high AlCl(3) content.     

Towards a biomimetic poly-aminoketone foldamer: synthesis of a triply protected monomer and its coupling to a dimer, trimer and tetramer

The design of a new biomimetic foldamer, relying on the weak amine-carbonyl interaction for secondary structure formation, is presented. The efficient synthesis of a triply protected monomer starting from glycidol was developed. This monomer contains a dioxolane-protected keto group that will allow liberation of the ketone functionality in the backbone once construction of the oligomeric backbone is complete. This monomer contains two additional orthogonal protecting groups at its two termini, the Fmoc and the TBDMS groups. The Fmoc group in particular permits oligomerisation towards the N terminus as seen in Fmoc solid phase peptide synthesis. Construction and full characterisation of a ketone-protected dimer, trimer and tetramer are reported.     

Synthesis of Selectively Substituted Lipocyclopolyamines

A general synthetic strategy for the preparation of polyazamacrocycles containing long aliphatic chains is reported. These compounds are 22- or 24-membered hexaazamacrocycles incorporating two diethylenetriamine subunits (H₂NCH₂CH₂NHCH₂CH₂NH₂) linked together either by two CH₂CH₂OCH₂CH₂ (see 4–6 ), two tetramethylene (see 7 ), or two pentamethylene (see 8 ) fragments. Whereas for compound 4 , one of the centrally located amine functionalities of the triamine subunit bears a hexadecyl chain, for compound 5 , two of such chains are centrally attached to both subunits. In macrocycles 6–8 , all six amino functionalities bear hexadecyl chains. Compounds 4–8 are potential candidates for the construction of selective chemical sensors such as specific electrodes for adenosine mono-, di-, and tri-phosphate. They may also be used for nucleoside polyphosphates extraction and/or transport.     

Synthesis and characterization of Gd2O3:Eu phosphor nanoparticles by a sol-lyophilization technique

The characterization and luminescence properties of nanostructured Gd₂O₃:Eu³⁺ phosphors synthesized by a sol-lyophilization process are presented. After preparation of gadolinium-based sols from gadolinium nitrate and ammonium hydroxide, the so-prepared sols were freeze dried at −10°C and calcinated at different temperatures. For temperatures lower than 1300 K, highly crystalline samples with the cubic structure can be obtained without concomitant grain growth of the particles (<50 nm). The luminescence spectra contain all possible transitions of Eu³⁺ with C₂ symmetry and present two major features: an increase of the luminescence efficiencies of the phosphors in comparison with that obtained by solid-state reaction and the presence of an additional peak at about 609 nm at the vicinity of the ⁵D₀→⁷F_0…4 transition.     

Liquid chromatography analysis of monosubstituted sulfobutyl ether-beta-cyclodextrin isomers on porous graphitic carbon

The retention behaviour of the three positional isomers of monosubstituted sulfobutyl ether-beta-cyclodextrin was investigated on a porous graphitic carbon (PGC) column. The influence of the mobile phase composition (nature and concentration of organic and electronic modifiers) was studied as well as the effect of column temperature. These hydrophilic and anionic analytes were highly retained on the PGC stationary phase compared to octadecyl bonded phases. The retention is mainly governed by a reversed-phase mechanism with electronic interaction playing a secondary role. An increase in solute retention and efficiency with temperature was observed. Successful isocratic separation with satisfactory baseline resolution of the three isomers of monosubstituted sulfobutyl ether-beta-cyclodextrin was achieved at 75 degrees C on a Hypercarb column by using ammonium acetate as electronic modifier in water-acetonitrile (83:17). The chromatographic methodology developed can be easily used for relative quantification of each isomer within a mixture and can be applied for semi-preparative purification of each one. The evaporative light scattering detector allows the detection of these non UV-visible absorbing molecules.     

A new 1D hybrid fluoroaluminate templated by an original tetramine

An original polyamine, 2,3 di-2-aminomethyl 1,4 diaminobut-2-ene (ten), characterized by single-crystal XRD analysis, has been synthesised and leads to a new hybrid fluoroaluminate [H₄ten] · (AlF₅)₂ by microwave heating assisted hydrothermal synthesis. The structure of [H₄ten] · (AlF₅)₂ is ab initio determined from powder data.