Dy(III) - and Yb(III) -Curcuminoid Compounds: Original Fluorescent Single-Ion Magnet and Magnetic Near-IR Luminescent Species

The multifunctional behavior of two mononuclear lanthanide compounds attached to a curcuminoid called 9?Accm has been investigated. The results show that [Dy(9?Accm)(2) (NO(3) )(dmf)(2) ] Yb(9?Accm)(3) (py)] behaves as a single-ion magnet and that both compounds display luminescent responses and exhibit affinity for graphite surfaces.     

Electrochemical determination of Cd<Superscript>2+</Superscript> at a titanium electrode modified with a lead film by square wave anodic stripping voltammetry

The modified titanium electrode with lead film (PbTiE) was used for determination of trace levels of cadmium using square wave anodic stripping voltammetry (SWASV). The measurement of cadmium on the PbTiE has the best reply under the following conditions of PbTiE preparation: 10^–3 mol L^–1 Pb²⁺ in HCl (pH 1.0), deposition potential of–1.40 V vs. Ag/AgCl/KCl_sat and deposition time of 300 s. The PbTiE reveals highly linear behavior in the concentration range 5 × 10^–8 to 10^–6 mol L^–1, with a limit of detection of 2 × 10^–9 mol L^–1. Interference of nine ionic species was evaluated. The measurements were carried out without removing dissolved oxygen from the solution.     

Stability to weak dissipative Bresse system

In this paper we study the Bresse system with frictional dissipation working only on the angle displacement. Our main result is to prove that this dissipative mechanism is enough to stabilize exponentially the whole system provided the velocities of waves propagations are the same. This result is significative only from the mathematical point of view since in practice the velocities of waves propagations are always different. In that direction we show that when the velocities are not the same, the system is not exponentially stable and we prove that the solution in this case goes to zero polynomially, with rates that can be improved by taking more regular initial data. Finally, we give some numerical result to verify our analytical results.     

A new rapid and micro-scale hydrolysis, using triethylamine citrate, for lipopolysaccharide characterization by mass spectrometry

Endotoxin (lipopolysaccharide, LPS) is, in general, composed of two moieties: a hydrophilic polysaccharide linked to a hydrophobic lipid A terminal unit and forms a major surface component of gram-negative bacteria. The structural features of LPS moieties play a role in pathogenesis and also involve immunogenicity and diagnostic serology. The major toxic factor of LPS resides in the lipid A moiety, anchored in the outer layer of the bacterium, and its relative biological activity is critically related to fine structural features within the molecule. In establishing relationships between structural features and biological activities of LPS it is of the utmost importance to develop new analytical methods that can be applied to the complete unambiguous characterization of a specific LPS molecule. Herein is presented a practical rapid and sensitive analytical procedure for the mass spectral screening of LPS using triethylamine citrate as an agent for both disaggregation and mild hydrolysis of LPS. It provides improved matrix-assisted laser desorption/ionization (MALDI) mass spectra and, in particular, affords the identification of fragments retaining labile substituents present in the native macromolecular LPS structures. The methods were developed and applied using purified LPS of Escherichia coli and Salmonella enterica, as well as more complex LPS of Actnobacillus pleuropneumoniae.     

Strong lower energy estimates for nonlinearly damped Timoshenko beams and Petrowsky equations

The purpose of this paper is to establish strong lower energy estimates for strong solutions of nonlinearly damped Timoshenko beams, Petrowsky equations in two and three dimensions and wave-like equations for bounded one-dimensional domains or annulus domains in two or three dimensions. We also establish weak lower velocity estimates for strong solutions of the nonlinearly damped Petrowsky equation in two and three dimensions. The feedbacks in consideration have arbitrary growth close to the origin. These results improve the strong lower energy decay rates obtained in our previous papers (Alabau-Boussouira in J Differ Equ 249:1145–1178, 2010; J Differ Equ 248:1473–1517, 2010) for strong solutions of the nonlinearly locally damped wave equation and extend to systems and to Petrowsky equation the method of Alabau-Boussouira (J Differ Equ 249:1145–1178, 2010; J Differ Equ 248:1473–1517, 2010). These results are the first ones for Timoshenko beams and Petrowsky equations.     

Can the crystallization rate be independent from the crystallization enthalpy? The case of amorphous silicon

The crystallization enthalpy measured in a large series of amorphous silicon (a-Si) materials varies within a factor of 2 from sample to sample (Kail et al 2011 Phys. Status Solidi RRL 5 361). According to the classical theory of nucleation, this variation should produce large differences in the crystallization kinetics leading to crystallization temperatures and activation energies exceeding 550?°C and 1.7 eV, respectively, the 'standard' values measured for a-Si obtained by self-implantation. In contrast, the observed crystallization kinetics is very similar for all the samples studied and has no correlation with the crystallization enthalpy. This discrepancy has led us to propose that crystallization in a-Si begins in microscopic domains that are almost identical in all samples, independently of their crystallization enthalpy. Probably the existence of microscopic inhomogeneities also plays a crucial role in the crystallization kinetics of other amorphous materials and glasses.     

Analysis of Argan Oil Adulteration Using Infrared Spectroscopy

The determination of argan oil adulteration by other vegetable oils is a real analytical challenge. The authentication of argan oil needs fast and simple analytical techniques for quality control and testing. This study focuses on the detection and quantification of argan oil adulteration with different edible oils, using midinfrared spectroscopy with chemometrics. Chemometric treatment of MIR spectra has been assessed for the classification and quantification of argan oil adulteration with sunflower or soybean oils. The potential of MID spectroscopy combined with partial least squares regression (PLS) as a rapid analytical technique for the quantitative determination of adulterants in argan oil has been demonstrated. A PLS model has been established to predict the concentration of soybean and sunflower oil as adulterants in the calibration range between 0% and 30% (w/w) in argan oil with good prediction performances in the external validation.     

Simulations of sooting turbulent jet flames using a hybrid flamelet/stochastic Eulerian field method

The stochastic Eulerian field method is applied to simulate 12 turbulent C₁?C₃ hydrocarbon jet diffusion flames covering a wide range of Reynolds numbers and fuel sooting propensities. The joint scalar probability density function (PDF) is a function of the mixture fraction, enthalpy defect, scalar dissipation rate and representative soot properties. Soot production is modelled by a semi-empirical acetylene/benzene-based soot model. Spectral gas and soot radiation is modelled using a wide-band correlated-k model. Emission turbulent radiation interactions (TRIs) are taken into account by means of the PDF method, whereas absorption TRIs are modelled using the optically thin fluctuation approximation. Model predictions are found to be in reasonable agreement with experimental data in terms of flame structure, soot quantities and radiative loss. Mean soot volume fractions are predicted within a factor of two of the experiments whereas radiant fractions and peaks of wall radiative fluxes are within 20%. The study also aims to assess approximate radiative models, namely the optically thin approximation (OTA) and grey medium approximation. These approximations affect significantly the radiative loss and should be avoided if accurate predictions of the radiative flux are desired. At atmospheric pressure, the relative errors that they produced on the peaks of temperature and soot volume fraction are within both experimental and model uncertainties. However, these discrepancies are found to increase with pressure, suggesting that spectral models describing properly the self-absorption should be considered at over-atmospheric pressure.     

A general method for proving sharp energy decay rates for memory-dissipative evolution equations

This Note is concerned with stabilization of hyperbolic systems by a distributed memory feedback. We present here a general method which gives energy decay rates in terms of the asymptotic behavior of the kernel at infinity. This method, which allows us to recover in a natural way the known cases (exponential, polynomial, …), applies to a large quasi-optimal class of kernels. It also provides sharp energy decay rates compared to the ones that are available in the literature. We give a general condition under which the energy of solutions is shown to decay at least as fast as the kernel at infinity. To cite this article: F. Alabau-Boussouira, P. Cannarsa, C. R. Acad. Sci. Paris, Ser. I 347 (2009).