Base‐Catalyzed Formation of Isoxazoles from Dialkyl Acetylenedicarboxylates and 2‐Nitroacetophenones

The reaction of dialkyl acetylenedicarboxylates with 1‐aryl‐2‐nitroethanones in the presence of pyridine leads to dialkyl 5‐aryloyl‐isoxazole‐3,4‐dicarboxylates through a novel mechanism, which involves a [2+2] cycloaddition/ring opening/cyclization sequence.     

Employing of Fe3O4/CuO/ZnO@MWCNT MNCs in the solvent-free synthesis of new cyanopyrroloazepine derivatives and investigation of biological activity

Molecular Diversity - In this research, we synthesized the Fe3O4/CuO/ZnO@MWCNT magnetic nanocomposites using water extract of Petasites hybridus rhizome, and the high performance of synthesized...     

Effets des forces de Coriolis sur le seuil convectif stationnaire d'une couche liquide confinée en cellule de Hele–Shaw annulaire en rotationEffects of the Coriolis forces on the stationary convectif threshold of a liquid layer confined in an annular Hele–Shaw Cell in rotation

The convective instability of a horizontal liquid layer confined in an annular Hele–Shaw cell subject to a constant rotation and submitted to a centrifugal gradient of temperature is investigated. Using a linear stability analysis, we study the effects of both Coriolis forces and curvature aspect on the stationary convective threshold when the Prandtl number is of the order of unity or larger than unity. We show that the Coriolis forces have a stabilizing effect, and the wave number is independent of these forces. However, a multicellular regime in the radial direction is observed for small Ekman numbers. The results related to the influence of the curvature are also shown. To cite this article: S. Ramezani et al., C. R. Mecanique 330 (2002) 633–640.     

Synthesis of Novel 3-(5-(Alkyl/arylthio)-1,3,4-Oxadiazol-2-yl)-8-Phenylquinolin-4(1H)-One Derivatives as Anti-HIV Agents

Novel quinolone derivatives featuring an 1,3,4-oxadiazole ring as a metal-chelating component and a benzyl group base on HIV-1 integrase inhibitors pharmacophore were designed and synthesized. An antiviral assay revealed that most analogues inhibited HIV-1 replication in the cell culture. Our results showed that compounds bearing small alkyl groups as R group were inactive in anti-HIV-1 assay, whereas compounds possessing benzyl or substituted benzyl at the same position showed good anti-HIV activity with the range of 20–57% at 100 μM concentration. Among them, 3-(5-((2-fluorobenzyl)thio)-1,3,4-oxadiazol-2-yl)-8-phenylquinolin-4-(1H)-one (compound 13) showed reasonable cell-based antiviral activity (EC₅₀ = 50 μM) with no considerable cytotoxicity (CC₅₀ > 100 μM) in the cell viability assay, suggesting that it may be amenable to further development for identifying new anti-HIV-1 agents. Docking studies using the later crystallographic data available for PFV integrase corroborate favorable binding to the active site of HIV integrase, providing a basis for the design of more potent analogues.     

Pressure dependence of the spectral lines of a high power, high pressure atomic fluorine laser pumped by a charge transfer from He2

Various transitions of a pressure tunable atomic fluorine laser have been observed over a rather wide spectral range, 634.8–755.2 nm, by exciting the atmospheric pressure of helium containing 0.2% F₂ in a preionized Blumlein discharge device with a charging voltage of 10–15 kV. The intensity of two quartet transitions, 739.9 and 755.2 nm, increases with pressure, whereas that of the other quartet and doublet lines, 634.8, 641.4, 712.8 and 731.1 nm, decreases with increasing atmospheric fill-pressure. The pumping mechanisms at high pressures appear to be different from those at relatively low pressures.     

Assessment of two analytical approaches in some nonlinear problems arising in engineering sciences

In this research, two powerful analytical methods are introduced to handle nonlinear good Boussinesq, heat transfer and coupled Burgers' equations. One is the homotopy-perturbation method (HPM) and the other is the variational iteration method (VIM). VIM is used to construct correction functionals using general Lagrange multipliers identified optimally via the variational theory. HPM converts a difficult problem into a simple one, which can be easily handled. The results attained in this paper confirm the idea that HPM and VIM are powerful mathematical tools and that they can be applied to a large class of linear and nonlinear problems arising in different fields of science and engineering.     

Application of Sol–Gel Based Poly(ethylene glycol)/Multiwalled Carbon Nanotubes Coated Fiber for SPME of Methyl tert-Butyl Ether in Environmental Water Samples

In this research, the sol–gel technology was applied for the preparation of solid-phase microextraction fibers for extracting of methyl tert-butyl ether (MTBE) from environmental water samples. For this purpose, two different polymers such as poly(ethylene glycol) (PEG) and combination of PEG and multiwall carbon nanotubes (MWCNTs) were prepared using sol–gel technology as coating procedure for the fibers. The pre-concentration process followed by GC–FID determination was used and the results evidenced that pre-concentration factor for PEG/CNTs fiber was approximately five times higher than PEG. Parameters affecting the extraction efficiency such as temperature, extraction time, stirring speed and salt effect for each fiber were investigated and optimized. On the optimal conditions, the linear range for MTBE with PEG and PEG/CNT fibers were 10–3,000 and 1–1,000 ng mL^?1 and the detection limits (S/N = 3) were 1.0 and 0.3 ng mL^?1, respectively. The sol–gel PEG/CNTs fiber has good performance and therefore relatively better figures of merit and experimental results such as thermal stability (up to 320 °C), average of life time (over 150 times) and repeatability (RSD < 4) in comparison to conventional PDMS/Carboxen fiber, which was already reported for determination of MTBE.