Solutions globales d'un problème de Cauchy linéaire

On résoud le problème de Cauchy pour des opérateurs aux dérivées partielles à coefficients polynomiaux par rapport aux variables d'espace dans des classes de Gevrey projectives. Nos résultats sont des versions globales du théorème de Cauchy-Kowalewski et du théorème de Nagumo.     

Intrinsic integrated optical temperature sensor based on waveguide bend loss

Curvature of a multimode integrated optical waveguide reduces the numerical aperture and induces radiation losses. In this paper, we study this phenomenon and we present a geometrical approach to calculate the local numerical aperture and the intensity attenuation. We exploit the bending effect on the local numerical aperture to make a new intrinsic temperature sensor. The simulation results are validated for the silica/silicone integrated optical case. The principal performances of the silica/silicone temperature sensor are the extended temperatures range (−50 to 200 °C) with an excellent linearity response (1%) between 20 and 200 °C.     

Ultrasound-Assisted Extraction of Carotenoids from Carrot Pomace and Their Optimization through Response Surface Methodology

Ultrasound-assisted extraction (UAE) was used to extract carotenoids from the carrot pomace. To investigate the effect of independent variables on the UAE, the response surface methodology (RSM) with central-composite design (CCD) was employed. The study was conducted with three independent variables including extraction time (min), temperature (°C), and ethanol concentration (%). The results showed that the optimal conditions for UAE were achieved with an extraction time of 17 min, temperature of 32 °C, and ethanol concentration of 51% of total carotenoids (31.82 ± 0.55); extraction time of 16 min, temperature of 29 °C, and ethanol concentration of 59% for a combination of β-carotene (14.89 ± 0.40), lutein (5.77 ± 0.19), and lycopene (2.65 ± 0.12). The non-significant (p > 0.05) correlation under optimal extraction conditions between predicted and experimental values suggested that UAE is the more productive process than conventional techniques for the extraction of carotenoids from the carrot pomace.     

Stereoselective synthesis of (2E) 3‐amino‐2‐(1H‐benzimidazol‐2‐yl)acrylate and symmetric bisacrylates by transamination reactions

A range of various amines 2(a–i) was tested in transamination reactions using ethyl 2‐(1H‐benzimidazol‐2‐yl)‐3‐dimethylamino‐acrylate 1a. The (E)‐s‐cis/trans conformation of some representative products 4 was analyzed by ¹H and ¹³C NMR spectra. The C‐2/C‐3 bond of the compounds 3(a–i) is strongly polarized by a push‐pull effect. In the same manner, reactions of ethyl 2‐(benzoxazol‐2‐yl)‐3‐dimethylamino‐acrylate 1c with 1,4‐diaminobenzene 2i, ethylenediamine 2i, and 1,5‐diaminomaphthalene 2k have been investigated and gave directly the corresponding symmetric bis‐acrylates 4(a–c) in good yields. © 1999 John Wiley & Sons, Inc. Heteroatom Chem 10: 446–454, 1999     

Synthesis and spectral properties of non-symmetrical red and near IR emitter dibenzoBODIPYs

New symmetrical and non-symmetrical benzoBODIPYs have been synthesized from diketones. For the two series the 3 and 5 positions have been substituted by different aromatic rings and onto benzo sub-units different groups have been introduced. The methodology of diketones self-condensation provides symmetrical dyes. By cross-condensation reaction, these positions can be differentiated and specific functions connected to the desired positions. These molecules have been fully characterized and their optical properties analyzed by both experimental and theoretical means. They are red to NIR emitters with a range of emission from 679 to 780?nm in CH₂Cl₂. They show maxima of absorption between 651?nm and 732?nm, strong ε of around 100,000?M^?1?cm^?1 and quite good quantum yields from 16% to 75%. The thienyl moiety on α-positions of the nitrogens generates the highest red shifts. Meanwhile dimethylamino groups in the same positions bring, besides chemical properties, proton sensitive dyes. The bromine atom onto the dibenzo sub-units exhibits good reactivity through Sonogashira coupling reactions. This approach provides multifunctional red to NIR dyes with endless possibilities of combination of chemical properties.     

Prediction of Low-Dose Aspirin-Induced Gastric Toxicity Using Nuclear Magnetic Resonance Spectroscopy-Based Pharmacometabolomics in Rats

Background: Low-dose aspirin (LDA) is the backbone for secondary prevention of coronary artery disease, although limited by gastric toxicity. This study aimed to identify novel metabolites that could predict LDA-induced gastric toxicity using pharmacometabolomics. Methods: Pre-dosed urine samples were collected from male Sprague-Dawley rats. The rats were treated with either LDA (10 mg/kg) or 1% methylcellulose (10 mL/kg) per oral for 28 days. The rats’ stomachs were examined for gastric toxicity using a stereomicroscope. The urine samples were analyzed using a proton nuclear magnetic resonance spectroscopy. Metabolites were systematically identified by exploring established databases and multivariate analyses to determine the spectral pattern of metabolites related to LDA-induced gastric toxicity. Results: Treatment with LDA resulted in gastric toxicity in 20/32 rats (62.5%). The orthogonal projections to latent structures discriminant analysis (OPLS-DA) model displayed a goodness-of-fit (R²Y) value of 0.947, suggesting near-perfect reproducibility and a goodness-of-prediction (Q²Y) of −0.185 with perfect sensitivity, specificity and accuracy (100%). Furthermore, the area under the receiver operating characteristic (AUROC) displayed was 1. The final OPLS-DA model had an R²Y value of 0.726 and Q²Y of 0.142 with sensitivity (100%), specificity (95.0%) and accuracy (96.9%). Citrate, hippurate, methylamine, trimethylamine N-oxide and alpha-keto-glutarate were identified as the possible metabolites implicated in the LDA-induced gastric toxicity. Conclusion: The study identified metabolic signatures that correlated with the development of a low-dose Aspirin-induced gastric toxicity in rats. This pharmacometabolomic approach could further be validated to predict LDA-induced gastric toxicity in patients with coronary artery disease.     

Investigation of the electrical properties of a new PPV derivative-based on a sandwich structure for opto-electronic applications

The opto-electronic properties of native poly(p-phenylene vinylene) (PPV) were tuned by the confinement of the π-conjugation and the incorporation of a sulphur group as a spacer in order to obtain a blue-green emitting polymer (PPVS). The energy band gap of the PPVS thin film has been measured by UV-vis absorption spectroscopy and evaluated to 2.87 eV. Current-voltage characteristics and impedance spectroscopy measurements performed on sandwich structures [ITO/PPVS/Al] are used to elucidate the conduction mechanisms. The static electrical characterisations showed a space charge limited conduction (SCLC) and a conductivity with low power frequency behaviour characteristic of a hopping transport in disordered materials. The impedance spectra can be discussed in terms of an equivalent circuit model designed as a parallel resistor R_P and capacitor C_P network in series with a resistor R_S. We extract numerical values of these parameters by fitting experimental data. Their evolution with bias voltages has shown that the SCLC mechanism is characterised by an exponential trap distribution.     

Coupled frequencies of a rectangular hydroelastic system with two fluids

This paper deals with the study of behaviour of an idealized 2D hydroelastic system involving two inviscid liquids with an elastic rectangular container. The main objective is to investigate the influence of the physical parameters on eigenfrequencies and eigenmodes of the system. The study extends the previous results obtained for hydroelastic systems with one fluid. The governing equations describing the behaviour of the system are analyzed by using the concept of normal modes and their solutions presented in the form of infinite series. The expansion coefficients for the velocity potentials are calculated by employing a new inner product that allows the orthogonalisation of the normal modes. An eigenfrequency equation is then derived from the existence condition of a nontrivial solution. The numerical calculations are performed by varying only some relevant parameters.     

Chloro(η6‐p‐cymene)(2‐methyl‐5‐oxo‐7‐phenyl‐5,6‐di­hydro‐2H‐1,2,4‐triaz­epine‐3‐thiol­ato‐κ2N4,S)­ruthenium(II)

The novel title ruthenium(II) complex, [RuCl(C₁₀H₁₄)(C₁₀H₁₀N₃OS)], was synthesized from the reaction of 1,2,4‐triazepine, a new class of bidentate ligands, with [Ru(p‐cymene)Cl₂]₂. The 1,2,4‐triazepine ligand is coordinated to the metal centre through the N‐4 and S atoms, forming a four‐membered chelate ring. This is the first structural example of a transition metal complex containing a 1,2,4‐triazepine ligand.