NH2SO3H and H6P2W18O62 · 18H2O-Catalyzed,Three-Component,One-Pot Synthesis of Benzo[c]acridine Derivatives

We report here two simple methods for the synthesis of benzo[c]acridine derivatives from three-component, one-pot condensation of 1-naphthylamine, dimedone, and a variety of substituted aldehydes in the presence of a catalytic amount of NH₂SO₃H or H₆P₂W₁₈O₆₂ · 18H₂O under solvent-free conditions at 120 °C or in refluxing ethanol.     

Tetrameric DABCO–Bromine Complex: A Novel Reagent for Regeneration of Carbonyl Compounds From Aldoximes and Ketoximes

An efficient and convenient conversion of aldoximes and ketoximes to the corresponding carbonyl compounds with tetrameric DABCO–bromine complex is reported.     

Efficient Synthesis of Bis-Coumarins Using Silica-Supported Preyssler Nanoparticles

Reaction of aldehydes and 4-hydroxycoumarin in the presence of catalytic amount of silica-supported Preyssler nanoparticles led to synthesis of bis-coumarins in excellent yields.     

Brønsted Acidic Ionic Liquids: New,Efficient, and Green Promoter System for the Synthesis of 4(3H)-Quinazolinones

A simple, inexpensive, and efficient new synthesis of 4(3H)-quinazolinones from the reaction of 2-aminobenzamide with aroyl chlorides in the presence of two new halogen-free Brønsted acidic ionic liquids, 3-methyl-1-(4-sulfonic acid)butylimidazolium hydrogen sulfate [(CH₂)₄SO₃HMIM][HSO₄] and 1-(4-sulfonic acid) butylpyridinium hydrogen sulfate [(CH₂)₄SO₃HPY][HSO₄], green and reusable catalysts, with excellent product yields under solvent-free conditions is reported. The products could be separated simply from the catalyst, and the catalyst could be recycled without noticeably decreasing the catalytic activity.     

Solvent‐Free Chemoselective Synthesis of 1,1‐Diacetates Catalyzed by Cu(NO3)2 · 3H2O

1,1‐Diacetates have been synthesized by the reaction of a variety of aldehydes with acetic anhydride in the presence of cupric nitrate as catalyst under solvent‐free conditions. Ketones were not converted to the corresponding diacetates under these conditions.     

Characterization of Colloidal Gas Aphron-Fluids Produced from a New Plant-Based Surfactant

Colloidal gas aphrons (CGAs) are gas bubbles with diameters ranging from 10 to 100 microns, generated by intense stirring of a surfactant solution at high speed. The surface activity and aggregation behavior of the surfactant affects the size/size distribution, stability, and other physicochemical properties of generated aphrons. Therefore, selection of a suitable surfactant is important for the generation of microbubbles with the desired properties. The goal of this articleis to investigate the potential use of a new plant-derived surfactant as an aphronizer surfactant in preparation of CGA-based drilling fluids for accomplishing desirable rheological and filtration properties. For this purpose, natural surfactant obtained from leaves of special tree, namely, Zizyphusspina Christi and used for preparation of aphron-based fluids. To achieve the research objectives, laboratory tests of suspension generation, microscopic visualization, initial yield, filtration loss, and rheological characterization with varying concentrations of surfactant and polymer were performed. Experimental results demonstrate that newly proposed biosurfactant has a great potential for application in preparation of CGA-based drilling fluids for implementation in petroleum drilling industry.      

Switching adaptive controllers to control fractional‐order complex systems with unknown structure and input nonlinearities

This article investigates the chaos control problem for the fractional‐order chaotic systems containing unknown structure and input nonlinearities. Two types of nonlinearity in the control input are considered. In the first case, a general continuous nonlinearity input is supposed in the controller, and in the second case, the unknown dead‐zone input is included. In each case, a proper switching adaptive controller is introduced to stabilize the fractional‐order chaotic system in the presence of unknown parameters and uncertainties. The control methods are designed based on the boundedness property of the chaotic system's states, where, in the proposed methods the nonlinear/linear dynamic terms of the fractional‐order chaotic systems are assumed to be fully unknown. The analytical results of the mentioned techniques are proved by the stability analysis theorem of fractional‐order systems and the adaptive control method. In addition, as an application of the proposed methods, single input adaptive controllers are adopted for control of a class of three‐dimensional nonlinear fractional‐order chaotic systems. And finally, some numerical examples illustrate the correctness of the analytical results. © 2014 Wiley Periodicals, Inc. Complexity 21: 211–223, 2015     

Preparation of a solid-state ion-selective electrode based on polypyrrole conducting polymer for magnesium ion

In this study, a potentiometric sensor based on a pencil graphite electrode (PGE) coated with polypyrrole doped with Titan yellow dye (PPy/TY) was prepared for potentiometric determination of magnesium ion in aqueous solutions. The structural characteristics of magnesium sensor electrode (PGE/PPy/TYMg) were studied using scanning electron microscopy and Fourier transform infrared along with energy-dispersive spectroscopy. Under the optimal conditions, the electrode reveals a good Nernstian behavior with slope of 28.27 ± 0.40 mV per decade over the concentration range of 1.0 × 10^?5–5.0 × 10^?2 M and a detection limit of 6.28 × 10^?6 M. The potentiometric response of fabricated electrode toward magnesium ion was found to be independent of the pH of the test solution in the pH range of 4.5–8.0. The electrode showed fast response time (<10 s) and good shelf lifetime (>2 months). The prepared magnesium sensor electrode can also be used as an indicator electrode in potentiometric titration of Mg²⁺ with EDTA with distinguished end point. The electrode revealed good selectivity with respect to many cations including alkali, alkaline earth, transition and heavy metal ions. The introduced magnesium electrode was used for measurement of Mg²⁺ ion in real samples without any serious interferences from other ions.     

Introducing Organic Gas Steam-Liquid Extraction as a New Preconcentration Method for Benzene,Toluene, Ethylbenzene and Xylene Determination in Water Samples by Gas Chromatography-Flame Ionization Detection

Journal of Analytical Chemistry - In this study, for the first time, the organic gas steam-liquid extraction by a special hand-made cell was used as a simple and inexpensive preconcentration...     

Energy,exergy, and sensitivity analyses of a new integrated system for generation of liquid methanol,liquefied natural gas,and crude helium using organic Rankine cycle,and solar collectors

Journal of Thermal Analysis and Calorimetry - The increasing growth of helium consumption in industries and the limited resources of this element are the challenges that industries will face in the...