Synthesis, X-ray diffraction analysis and NMR studies of (Z)-2-methyl-3-triphenylstannyl-3-pentene-2-ol

The synthesis of (Z)-2-methyl-3-triphenylstannyl-3-pentene-2-ol and its characterization by an X-ray diffraction study and multinuclear NMR are reported. The tin atom exhibits a distorted tetrahedral SnC₄ geometry with the four Sn---C bond distances experimentally equivalent. The slight distortion from the ideal tetrahedral geometry is because of the presence of a weak intramolecular HO → Sn interaction of 3.012(3) Å which produces a loose four-membered ring. The title compound was characterized in solution by ¹H, ¹³C and ¹¹⁹Sn NMR, and the persistence of the weak intramolecular HO → Sn coordination in solution was revealed by ¹³C and ¹¹⁹Sn secondary isotope multiplet of partially labelled entities (SIMPLE-NMR) experiments.     

Belief functions contextual discounting and canonical decompositions

In this article, the contextual discounting of a belief function, a classical discounting generalization, is extended and its particular link with the canonical disjunctive decomposition is highlighted. A general family of correction mechanisms allowing one to weaken the information provided by a source is then introduced, as well as the dual of this family allowing one to strengthen a belief function.     

Characterization and optimization of magnetron sputtered Sc/Si multilayers for extreme ultraviolet optics

Scandium/silicon multilayers have been deposited by magnetron sputtering and characterized by several techniques. Experimental peak reflectances of 0.22 and 0.37 have been measured respectively at wavelengths of 40 nm and 46 nm, for 10° incidence angle. The corresponding theoretical values for a perfect Sc/Si structure are respectively 0.38 and 0.57. In order to explain these differences between calculated and measured reflectivity, thin film and multilayer characterizations have been done. Effects of multilayer imperfections on the reflectivity have been estimated independently by means of simulation. Based on these results, a new design of Sc/Si multilayer is proposed with top layer thickness optimization. With this design, the experimental peak reflectance reaches 0.46 at a wavelength of 46 nm. PACS 78.67.Pt; 78.66.-W; 81.15.Cd     

X-ray properties and interface study of B4C/Mo and B4C/Mo2C periodic multilayers

We present a comparative study of B₄C/Mo and B₄C/Mo₂C periodic multilayer structures deposited by magnetron sputtering. The characterization was performed by grazing incidence X-ray reflectometry at two different energies and high resolution transmission electron microscopy. The experimental results indicate the existence of an interdiffusion layer at the B₄C-on-Mo interface in the B₄C/Mo system. Thus, the B₄C/Mo multilayers were modeled by an asymmetric structure with three layers in each period. The thickness of B₄C-on-Mo interfacial layer was estimated about 1.1 nm. The B₄C/Mo₂C multilayers present less interdiffusion and are well modeled by a symmetric structure without interfacial layers. This study shows that B₄C/Mo₂C structure is an interesting alternative to B₄C/Mo multilayer for X-ray optic applications.     

Isotopic composition and concentration measurements of atmospheric CO2 with a diode laser making use of correlations between non-equivalent absorption cells

Correlations between a sample and a sealed reference cell of a tunable diode laser spectrometer for the measurement of the isotopic composition (δ ¹³C) and the concentration of atmospheric carbon dioxide in air have been investigated. Likely due to fluctuations of the laser emission profile, these correlations have been used to improve the performance of the instrument. In a comparison with isotope ratio mass spectrometer and gas chromatographic measurements, an accuracy of 0.15‰ for δ ¹³C and 0.05 ppmv for the CO₂ concentration is demonstrated for 40 s integration time. Long-term stability and field deployment of the instrument have been investigated during a few days measurement campaign in Paris.     

Development of Al-based multilayer optics for EUV

We report on the development of multilayer optics for the extreme ultra-violet (EUV) range. The optical performance of Al-based multilayer mirrors is discussed with regard to promising reflectivity and selectivity characteristics and the problems of the interfacial roughness for this type of multilayers. We demonstrate a possibility to reduce the average roughness by introducing additional metal layer (W or Mo) rather than depositing a buffer layer at each interface. We have prepared and tested Al/SiC, Al/W/SiC and Al/Mo/SiC multilayers of various periods for the spectral range from 15 to 40 nm, which is the range of increasing interest for high-order harmonic generation, synchrotron radiation and astrophysics. The structure of the three-component systems has been optimized in order to obtain the best reflectivity for each wavelength within the spectral range. We have shown that introduction of refractory metal in Al-based periodic stack can improve the optical performance of multilayer reflecting coatings designed for the EUV applications.     

Two channel multilayer mirrors for astrophysics

A two-channel mirror reflecting both Fe-IX/X (λ = 17.1 nm) and He-II (30.4 nm) resonance lines at near normal incidence has been designed, fabricated and characterized. These two passbands are often chosen in space instruments designed for the observation of the solar corona. The mirror structure used for optimization is a superposition of two periodic multilayers with three components per period. It has been designed by using optimization software with an appropriate merit function. The theoretical reflectivity for both resonance lines can reach 0.25. It is shown that, by using a set of filters, one can select either the Fe-IX/X or the He-II channel. The spectral response of the two-channel mirror has been measured on synchrotron radiation source on a large wavelength range, from 12 nm to 35 nm. Experimental reflectivity reaches 0.32 for the Fe-IX/X line and 0.19 for the He-II line.     

CP-MAS C NMR and FT-IR investigation of the degradation reactions of polymer constituents in wood welding

The essential chemical modifications involving the polymeric constituents of wood in friction welding occur in the first 5-6 s slowing down or even stopping afterwards. FT-IR and CP-MAS ¹³C NMR of the welded area of wood have shown dehydration and an apparent increase in the crystallinity of cellulose. A certain level of hemicelluloses degradation occurs, accompanied by the generation of some furfural. Cellulose degradation is instead very slight. Both analytical techniques show an increase in the proportion of lignin in the welding interphase. A proportion of methoxy groups of lignin is de-etherified to phenolic hydroxy groups. Self-condensation of lignin occurs by internal rearrangement with the formation of Ar-Ar and Ar-CH₂-Ar bridges. This progresses throughout the whole process of welding. The formation of C-O-C bridges, although stopping after 6 s welding, at the start of wood carbonisation, also appears to contribute to the increase in cross-linking of the lignin network.     

Miniaturized monolithic disks for immunoadsorption of cardiac biomarkers from serum

Immunoadsorbers based on 2.0 × 6.0 mm i.d., epoxy-bearing, methacrylate-based monolithic disks were developed in order to target myoglobin and N-terminal pro-natriuretic peptide (NT-proBNP), two biomarkers involved in cardiovascular disease. In both cases, antibodies were successfully coupled to the polymeric disk material. The developed immunoadsorbers permitted the selective isolation of myoglobin and NT-proBNP from human serum. Myoglobin was successfully isolated and detected from serum samples at concentrations down to 250 fmol μL⁻¹. However, the affinity of the antibodies was not sufficient for the analysis of low-concentration clinical samples. Frontal analysis of anti-NT-proBNP disks revealed the ability of the immunoadsorber to bind up to 250 pmol NT-proBNP, which is more than sufficient for the analysis of clinical samples. Anti-NT-proBNP disks showed good stability over more than 18 months and excellent batch-to-batch reproducibility. Moreover, anti-NT-proBNP disks permitted the isolation of NT-proBNP at concentrations down to 750 amol μL⁻¹ in serum, corresponding to concentrations of strongly diseased patients. Using reversed-phase trapping columns, the detection of NT-proBNP eluted from immunoadsorbers by mass spectrometry was achieved for concentrations down to 7.8 fmol μL⁻¹.