Furannes et pyrroles disubstitues en 2,3. XVII. Structure des composés formés par eyanuration des halogénométhyl-2 méthoxycarbonyl-3 et −5 furannes

Treatment of methyl 2-bromomethylfuran-3-carboxylate with potassium cyanide yielded methyl 2-cyanomethylfuran-3-carboxylate, methyl 2-methyl-5-cyanofuran-3-carboxylate and two unusual products which appeared by nucleophilic substitution of the activated methylene group of the preceding furylacetonilrile. Products from the cyanide displacement reaction of methyl 5-chloromethylfuran-2-carboxylate are formed in the same way and their previously described formulas are corrected. On the other hand, it was pointed out that phosphorus oxychloride-pentachloride transformation of 2-cyanomethylfuran-3-carboxylic acid leads to 4,6-disubstituted furo[3,2-c]pyridines.     

Hydrolysis of 1-methyl-2-methylthio-Δ2-imidazoline

New results in SN methyl transfer reaction in the series of Δ₂-imidazoline with and without quaternary salt catalyst are reported. The hydrolysis of monocyclic compounds containing the 2-alkyl thio, uronium group leads to the formation of a salt. Rearrangement reactions observed in the “uncatalysed reaction” may be due to a true catalytic reaction.     

Sun-reactive Skin Type in 4912 French adults participating in the SU.VI.MAX study

Phototype classifications were initially developed in an attempt to predict the skin reactions of patients to phototherapy and are now widely used to advise individuals with regard to sun protection. A transversal study was conducted on the SU.VI.MAX cohort to estimate the frequency of sun-reactive skin features in a large, general adult population-based sample, and to describe the associations between these features. The data were collected 3 years after the beginning of the SU.VI.MAX nutritional intervention study on 4912 volunteers (2868 women aged 35-60 years and 2044 men aged 45-60 years). A multiple correspondence analysis was performed to study the associations between the features. The results showed that these features correspond to a one-dimensional phenomenon, which allowed us to establish a score to summarize skin sensitivity to sun exposure. Furthermore, we found a link between gender and phototype using the Césarini classification (phototype > or = IV: 37% of women, 47% of men). The analysis of the relationship with sun-reactive skin features and the score revealed the same trend. Phenotypic evaluation appears to be a good estimator of skin sensitivity to sun exposure for clinical screening or for use in research, and is easy to collect at a lower cost. Moreover, the sun sensitivity difference between gender should be considered in education about photoprotection.     

Raman Scattering from Liquid Crystals

Abstract

The use of Raman scattering technique as a tool for studying local order in complex liquid crystal systems is illustrated by three examples, namely the locally anisotropic liquid L-phase, lipid membranes, and PDLC's.     

Insights into the potentiometric response behaviour vs. Li+ of LiFePO4 thin films in aqueous medium

The potentiometric response of PLD-made LiFePO(4) thin films versus Li(+) ions in aqueous solutions has been investigated, and a sensitivity of 54 mV dec(-1) has been observed in a Li(+) concentration range of 1-10(-4) M. Physical and electrochemical measurements of electrodes aged in aqueous medium show a slight surface oxidation with formation of heterosite-FePO(4) that we show to be responsible for the stable potential response measured. Cyclic voltamperometry measurements operated in different Li(+) concentration clearly highlight the key relation between the material lithium ion insertion/de-insertion capability and its potentiometric sensing response implying a faradaic-governed sensing mechanism. Based on such a finding, selection criteria (enlisting among others the potential of the redox couple, the nature of the insertion process) are herein underlined in the search for new sensitive materials.     

Thermodynamic and neutron scattering study of hydrogen adsorption in two mesoporous ordered carbons

Two mesoporous ordered carbon materials (MOCs) have been synthesized from silica templates by using sucrose as the carbon precursor. The textural characterization using Ar, N2, and CO2 adsorption combined with neutron diffraction showed that the two samples exhibit a significant microporous volume close to 0.5 cm3/g and an ordered network of mesopores. For both MCM48 and SBA15 templated carbons, adsorption first proceeds with the filling of micropores and then by the filling of mesopores with an adsorption energy close to the enthalpy of vaporization of bulk hydrogen. The hydrogen isosteric heat of adsorption in the micropores (6-8 kJ/mol) is significantly larger than that on the graphite surface (approximately 4 kJ/mol) but still too small for a reasonable use of these MOCs as hydrogen adsorbents for storage at room temperature. The neutron scattering study showed that the structure at 10 K of the adsorbed deuterium phase is poorly organized; it exhibits short and medium range orders of about 13 angstroms in micropores and about 20 angstroms in mesopores, respectively. The average distance between adsorbed molecules decreases with coverage by about 10%. In the mesopores, the diffracted line is consistent with a pseudohexagonal packing.     

Adsorption of simple gases in MCM-41 materials: the role of surface roughness

This paper reports the development and testing of atomistic models of silica MCM-41 pores. Model A is a regular cylindrical pore having a constant section. Model B has a surface disorder that reproduces the morphological features of a pore obtained from an on-lattice simulation that mimics the synthesis process of MCM-41 materials. Both models are generated using a similar procedure, which consists of carving the pore out of an atomistic silica block. The differences between the two models are analyzed in terms of small angle neutron scattering spectra as well as adsorption isotherms and isosteric heat curves for Ar at 87 K and Xe at 195 K. As expected for capillary condensation in regular nanopores, the Ar and Xe adsorption/desorption cycles for model A exhibit a large hysteresis loop having a symmetrical shape, i.e., with parallel adsorption and desorption branches. The features of the adsorption isotherms for model B strongly depart from those observed for model A. Both the Ar and Xe adsorption branches for model B correspond to a quasicontinuous pore filling that involves coexistence within the pore of liquid bridges and gas nanobubbles. As in the case of model A, the Ar adsorption isotherm for model B exhibits a significant hysteresis loop; however, the shape of the loop is asymmetrical with a desorption branch much steeper than the adsorption branch. In contrast, the adsorption/desorption cycle for Xe in model B is quasicontinuous and quasireversible. Comparison with adsorption and neutron scattering experiments suggests that model B is too rough at the molecular scale but reproduces reasonably the surface disorder of real MCM-41 at larger length scales. In contrast, model A is smooth at small length scales in agreement with experiments but seems to be too ordered at larger length scales.     

Interplay of low-energy phonons and magnetic excitations in the Kondo insulator YbB12

Peculiarities in the lattice dynamics of the Kondo insulator Y bB(12) have been studied by inelastic neutron scattering. Selected phonon modes were traced above and below the temperature region (T ~ 50 K) where the gap opens in the electron density of states. The intensities of some low-energy modes exhibit an anomalous temperature dependence for q vectors close to the Brillouin zone boundary, suggesting a renormalization of the phonon eigenvectors. This effect is thought to arise from a coupling with magnetic excitations of the same symmetry, which exist at nearby energies. It is argued that this magnetovibrational coupling may in turn play a role in the steep temperature crossover existing in Y bB(12) between the low-temperature (Kondo insulator) and high-temperature (incoherent spin-fluctuation) regimes, which is rapidly suppressed by lighter Zr substitution.     

The economics of a closed-loop supply chain with remanufacturing

This study deals with joint decisions on pricing and production lot-sizing in a closed-loop supply chain consisting of manufacturing and remanufacturing operations. This study emphasizes the economic analysis of this hybrid system with substitution between the new and the remanufactured versions of the same product. We develop analytical models under a newsvendor framework bearing the following questions in mind. Can a hybrid system operate cost-effectively? Can it outperform the manufacturing-only system? If yes, to what extent and under what conditions? If not, what are the key factors that cause underperformance? This study formulates a multi-variable optimization problem and performs mathematical and numerical analysis. Results show that the hybrid system does not outperform the manufacturing-only system under a generic setting, but achieves better performance under conditions with a higher degree of substitution and/or a lower remanufacturing cost. In this scenario, participating in remanufacturing is not only an issue of environmental responsibility, but a profit-boosting option.