Alcoylation d'acridanone-9. Premiers exemples de O-alcoylation dans cette série de composés

The results of nucleophilic substitution of the 2-methoxy-9-acridone are discussed in terms of competition between both ionic sites N^? and O^?, of the molecule. They are the first examples of O-alkylation of substituted 9-acridone.     

Influence of crosslink density and chain flexibility on mechanical properties of model epoxy networks

Fully cured epoxy networks having different architectures were prepared by introducing either a monoamine acting as a chain extender or an aliphatic epoxy monomer. As expected an increase in the amount of the difunctional amine leads to a decrease in the crosslink density whereas the introduction of an aliphatic epoxy comonomer leads to more flexible chains between crosslinks. Values of the Young modulus and the dependence of the yield stress as a function of temperature were related to the occurrence and amplitude of secondary relaxations. The fracture toughness at room temperature was clearly associated with the glass transition temperature as a consequence of plastic deformation, rather than with chain scission.     

Poly(ethylene oxide) macromonomer based hydrogels as a template for the culture of hepatocytes

Macromonomer based poly(ethylene oxide) (PEO) hydrogels were tested with respect to their ability to serve as a template for the survival and the growth of hepatocytes. Two systems were considered : either the surface of preexisting hydrogels, with controlled structural parameters, were seeded with isolated rat hepatocytes or the hepatocytes were dispersed in physiological medium containing the macromonomer/initiator and heated to 37°C. In the first case, cells were examined at given times after spreading over two days. The results were compared to those observed for the dispersion of fibroblasts onto a surface of the same type of hydrogels. The effects of the structure of the hydrogels and its chemical nature on the extent of hepatocyte attachment (or encapsulation) and the morphology were investigated.     

Synthese de nouvelles 1H,3H pyrido[2,3-d] pyrimidinediones-2,4

The synthesis and spectroscopic properties of a series of new substituted 2,4-dioxopyrido[2,3-d]pyrimidines are reported.     

Impact of coated calcium carbonate nanofillers and annealing treatments on the microstructure and gas barrier properties of poly(lactide) based nanocomposite films

Amorphous poly(lactide) (PLA) and nanocomposite films were prepared from melt‐blending with precipitated calcium carbonate nanofillers (PCC). Nanocomposites based on uncoated PCC (PCC‐UT), stearic acid coated PCC (PCC‐S), and poly(ε‐caprolactone) coated PCC (PCC‐P) were investigated for an inorganic content fixed to 8 wt %. Using coated nanofillers allowed preserving both PLA average molar mass and thermal stability while enhancing the nanofiller dispersion state. Poly(ε‐caprolactone) was identified as the best coating for optimized morphology and thermal properties. Maxwell law accurately described the increase in oxygen barrier properties observed for the nanocomposites based on PCC‐S. A modified Maxwell law was proposed to take account of the additional increase in barrier properties evidenced for the PLA/PCC‐P nanocomposites and assigned to the particularly strong compatibility between PCL and PLA. Different annealing conditions were investigated to respectively study the impact of physical ageing and PLA crystallization on gas permeability. Different extents of physical ageing did not significantly modify the oxygen transport properties. However, a high permeability decrease was observed for the semicrystalline nanocomposites with respect to the amorphous reference PLA film. Finally, the gain in barrier properties was shown to result from both contribution of the nanofillers and the crystalline phase. © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016 , 54, 649–658     

Pendimethalin in surface waters of rivers in the proximity of irrigated paddy fields by solid phase microextraction and gas chromatography

The aim of this study was to develop an analytical methodology for the determination of the herbicide pendimethalin in river waters in the towns of Turvo and Meleiro in the southern region of Santa Catarina State, Brazil. The method, based on solid phase microextraction (SPME) followed by separation and detection by gas chromatography (GC) and electron capture detection (ECD), respectively, was optimised and validated. The limits of detection (LOD) and quantification (LOQ) of 0.02 and 0.06?µg?L^?1, respectively, and recovery values in the range of 86.2 (±11.5)% to 103.4 (±9.5)% were obtained. It was verified that 53 river water samples showed contamination by pendimethalin at levels that ranged from 0.06 to 0.38?µg?L^?1.     

HPLC�CDAD Analysis of Hydrochlorothiazide and Irbesartan in Hypertensive Patients on Fixed-Dose Combination Therapy

Hydrochlorothiazide (HCTZ) and the angiotensin II type 1 receptor antagonist (ARB) irbesartan (IRBE) are well-known antihypertensive drugs, frequently administered as a low-dose combination in a single pill. In this work, a simple, sensitive, and selective high-performance liquid chromatographic (HPLC) method with diode-array detection was developed for simultaneous determination of HCTZ and IRBE levels in the plasma of hypertensive patients given a fixed combination of 12.5 mg HCTZ and 300 mg IRBE. Compounds were extracted from acidified plasma samples with 3 mL ethyl acetate, and eluted at 6 and 19 min from a C₄ column by elution with an acetonitrile?Cphosphate buffer (pH 3.6) mobile-phase gradient at a flow rate of 1 mL min^?1. The assay was linear over the ranges 2.5?C500 and 20?C4,000 ng mL^?1 for HCTZ and IRBE, respectively. Overall intra-assay and inter-assay variation were within acceptance limits. Limits of quantification were 2.5 and 20 ng mL^?1 for HCTZ and IRBE, respectively. Plasma samples remained stable for 12 h at room temperature, through three thaw?Cfreeze cycles, and for 2 and 7 months at ?20 °C. In hypertensive patients, residual concentrations were 22.3 ± 6.0 and 241.8 ± 39.0 ng mL^?1 for HCTZ and IRBE, respectively. There was no interference from other co-administered drugs. Despite the different physicochemical properties of HCTZ and IRBE, our method enables accurate measurement of both drugs for assessment of compliance by patients treated by fixed-dose combination therapy with HCTZ?CIRBE.     

Surface modification of calcium carbonate nanofillers by fluoro- and alkyl-alkoxysilane: Consequences on the morphology,thermal stability and gas barrier properties of polyvinylidene fluoride nanocomposites

Nano-sized precipitated silica coated calcium carbonate fillers (PCC-Si) were modified by an alkyl- and a fluoro-alkoxysilane derivative, respectively. PCC-Si surface modification was characterized by elemental analysis, Fourier transform infrared analysis and X-ray photoelectron spectroscopy. The modification conditions used for surface treatment led to a similar grafting density (around 3.2 μmol m^?2) for the two alkoxysilane derivatives. A significant decrease of filler hydrophilicity was observed after the alkoxysilane treatment. Nanocomposites prepared by melt mixing the modified fillers (10 wt.%) with polyvinylidene fluoride (PVDF) depicted no color change, an enhanced filler dispersion state with an homogeneous dispersion of very small filler aggregates (less than 150 nm diameter size), an increase of the thermal stability at high temperature and no change of the PVDF crystalline morphology. The oxygen permeability decrease measured on the nanocomposite prepared from the perfluorooctyltriethoxysilane modified filler was in good agreement with Maxwell law. The permeability increase evidenced for the nanocomposite based on the octyltriethoxysilane modified PCC suggested the formation of weak interfaces in this system.     

Une Autre Approche A La Synthese De Derives Benzyles Des Monosaccharides Reducteurs. Etude Des Equilibres Pyrannose-Furannose Par R.M.N. Du Carbone-13

Abstract

Perbenzyl derivatives of d-glucose, d-mannose, d-galactose, d-xylose, d-ribose and l-arabinose were prepared by treatment of reducing sugars with benzyl bromide in DMSO in the presence of potassium hydroxyde and the composition (α/β, Pyranoside/Furanoside) of the reaction mixtures determined by ¹³C-Nuclear Magnetic Resonance spectroscopy. Most of the per-O-benzyl glycosides were obtained in crystalline form unlike the corresponding methyl per-O-benzyl glycosides. Benzylation of d-mannose gave almost exclusively penta-O-benzyl-β-d-mannopyranoside (≥ 95%) as cristalline material. Benzylated reducing sugars were further obtained in good yield by acid hydrolysis of above compounds.