Zinc‐containing ionic liquid as a dual solvent‐catalyst in base‐free condensations under ultrasonic irradiation

In this study, natural‐based ionic liquid (IL) using caffeine (Caff), trietahnolamine (TEA) and ZnBr₂, [Caff‐TEA]⁺[ZnBr₃]^?, which features high catalytic activity and environmentally‐friendly nature was synthesized with melting point of 76 °C by a facile method. The synthesized [Caff‐TEA]⁺[ZnBr₃]^? has high catalytic activity as both of catalyst and solvent in condensation reactions for the synthesis of benzylidenes, bis‐hydroxyenones and xanthenes. Synthesized IL was characterized by proton nuclear magnetic resonance (¹HNMR), Fourier transform infrared spectroscopy (FT‐IR), X‐ray diffraction (XRD) and Energy‐dispersive X‐ray spectroscopy (EDX) analysis. Also synthesized heterocycles were characterized by FT‐IR, proton nuclear magnetic resonance (¹HNMR) and carbon nuclear magnetic resonance (¹³CNMR).     

Sulfonic acid-functionalized Fe3O4-supported magnetized graphene oxide quantum dots: A novel organic-inorganic nanocomposite as an efficient and recyclable nanocatalyst for the synthesis of dihydropyrano[2,3-c]pyrazole and 4H-chromene derivatives

In this research, the main emphasis has been focused on the preparation of a novel Fe₃O₄-supported propane-1-sulfonic acid-grafted graphene oxide quantum dots (Fe₃O₄@GOQD-O-(propane-1-sulfonic acid)) that it was readily synthesized via a five-step procedure as a hitherto unreported magnetic nanocatalyst. This newly prepared Fe₃O₄@GOQD-O-(propane-1-sulfonic acid) nanocomposite was structurally well-established by different analytical techniques including Fourier transform infrared (FT-IR), X-ray diffraction (XRD), energy-dispersive X-ray (EDX), thermal gravimetric analysis (TGA), field emission gun-scanning electron microscope (FESEM), high-resolution transmission electron microscopy (HRTEM) and vibrating sample magnetometer (VSM) analyses. The high catalytic performance of this nanocomposite was exhibited in one-pot synthesis of dihydropyrano[2,3-c]pyrazole and 4H-chromene derivatives under mild conditions. Low reaction times, excellent yields of the products, benignity of the catalyst, easy reaction work-up and magnetic recyclability of the catalyst are the main advantages of the present protocol. Also, our research indicated that the Fe₃O₄@GOQD-O-(propane-1-sulfonic acid) could be reused up to five times without considerable loss of catalytic activity.     

Copper-immobilized ionic liquid as an alternative to organic solvents in the one-pot synthesis of bioactive dihydropyrano[2,3-c]pyrazole derivatives

In this study, a novel Cu-immobilized ionic liquid (IL)was designed, characterized, and employed as both promoter and solvent in the synthesis of some dihydropyrano[2,3-c]pyrazoles. The synthesized ionic liquid was characterized by ¹H NMR, ¹³C NMR, FTIR, ICP and EDX analysis and showed high catalytic activity to proceed the synthesis of bioactive dihydropyrano[2,3-c]pyrazole derivatives. This method has the advantage of using the IL as a green medium for the synthesize of the products in high to excellent yields within short reaction times.     

Synthesis and characterization of new fluorinated photoactive polyamides based on xanthene pendant: Evaluation of antibacterial and heavy metal ions removal behavior

A series of novel organosoluble polyamides (PAs) bearing different functional groups such as flexible ether, substituted imidazole, and xanthene rings and electron-withdrawing CF₃ groups were synthesized from diamines and various dicarboxylic acids. The structures of diamines and PAs were fully characterized by elemental analysis, Fourier transform infrared spectroscopy, and proton nuclear magnetic resonance spectroscopy. The PAs showed good solubility in aprotic and polar organic solvents, with high thermal stability exhibiting the glass transition temperatures (T_gs) and 10% weight loss temperatures (T₁₀%) in the range of 184–277°C and 410–480°C in N₂ atmosphere, respectively. These polymers showed fluorescence emission upon irradiation with UV light. Diamine compounds and two of synthesized polymers were also screened for antibacterial activity against gram-positive and gram-negative bacteria, and the obtained results for all four combinations showed good inhibition. Extraction capability for heavy metal ions such as Cr³⁺, Pb²⁺, Hg²⁺, Cd²⁺, and Co²⁺ from aqueous solutions was also tested at 25°C and pH 7–8.     

An approximation of the analytical solution of the Jeffery-Hamel flow by decomposition method

Many researchers have been interested in application of mathematical methods to find analytical solutions of nonlinear equations and for this purpose, new methods have been developed. Since most of fluid mechanics problems due to boundary layer are strongly nonlinear, so analytical solution of them is confronted with some difficulty. In this Letter, the Jeffery-Hamel flow—a nonlinear equation of 3rd order—is studied by Adomian decomposition method. After introducing Adomian decomposition method and the way of obtaining Adomian's polynomial, we solved the problem for divergent and convergent channels. Finally, velocity distribution and shear stress constant is depicted at various Reynolds numbers and comparing our results with some earlier works illustrated their excellent accuracy.     

Optimization by Response Surface Methodology of the Adsorption of Anionic Dye on Superparamagnetic Clay/Maghemite Nanocomposite

Russian Journal of Applied Chemistry - Magnetic nanoparticles and clay minerals combine to form a class of advanced nanocomposites that would possess exceptional adsorption, magnetism, and...     

Green synthesis of silver nanoparticles using Eucalyptus comadulensis leaves extract and its immobilization on magnetic nanocomposite (GO-Fe3O4/PAA/Ag) as a recoverable catalyst for degradation of organic dyes in water

The magnetically recyclable graphene oxide-Fe₃O₄/polyallylamine (PAA)/Ag nanocatalyst was prepared via a green route using Eucalyptus comadulensis leaves extract as both reducing and stabilizing agent. The catalytic activity of this nanocatalyst was investigated for the reduction reaction of methylene blue and methyl orange in the presence of NaBH₄ in aqueous medium at room temperature. The prepared nanocatalyst was characterized by different methods such as Fourier transformed infrared spectroscopy, X-ray diffraction, scanning electron microscopy–energy dispersive X–ray spectroscopy, thermogravimetric analysis, vibrating sample magnetometer, transmission electron microscopy, and UV–visible spectroscopy. The results show that graphene oxide/PAA/Ag nanocatalyst has good activity and recyclability, and can be reused several times without major loss of activity in the reduction process. The apparent rate constants of the methyl orange (MO) and methylene blue (MB) were calculated to be 0.077 s⁻¹ (3 mg of catalyst) and 0.15 s⁻¹ (2 mg of catalyst), respectively.     

Locating series FACTS devices for multi-objective congestion management improving voltage and transient stability

Transmission congestion management is a vital task in electricity markets. Series FACTS devices can be used as effective tools to relieve congestion mostly employing Optimal Power Flow based methods, in which total cost as the objective function is minimized. However, power system stability may be deteriorated after relieving congestion using traditional methods leading to a vulnerable power system against disturbances. In this paper, a multi-objective framework is proposed for congestion management where three competing objective functions including total operating cost, voltage and transient stability margins are simultaneously optimized. This leads to an economical and robust operating point where enough levels of voltage and transient security are included. The proposed method optimally locates and sizes series FACTS devices on the most congested branches determined by a priority list based on Locational Marginal Prices. Individual sets of Pareto solutions, resulted from solving multi-objective congestion management for each location of FACTS devices, are merged together to create the comprehensive Pareto set. Results of testing the proposed method on the well-known New-England test system are discussed in details and confirm efficiency of the proposed method.     

Theoretical Investigation into Production of Double-Λ Hypernuclei from Stopped Ξ − on 6Li

We have investigated theoretically a feasible nuclear reaction to produce light double-Λ hypernuclei by choosing a suitable target. In the reaction from stopped Ξ ^? on ⁶Li target light doubly-strange nuclei, ${^5_{\Lambda\Lambda}{\rm H}}$ and ${^6_{\Lambda\Lambda}{\rm He}}$ , are produced: we have calculated the formation ratio of ${^5_{\Lambda\Lambda}{\rm H}}$ to ${^6_{\Lambda\Lambda}{\rm He}}$ for Ξ ^? absorptions from 2S, 2P and 3D orbitals of Ξ ^?–⁶Li atom by assuming a d?α cluster model for ⁶Li. From this cluster model the d?α relative wave functions has a node due to Pauli exclusion among nucleons belonging to d and α clusters. Two kinds of d?α wave functions, namely 1s relative wave function with a phenomenological one-range Gaussian (ORG) potential and that of an orthogonality-condition model (OCM) are used. It is found that the probability of ${^5_{\Lambda\Lambda}{\rm H}}$ formation is larger than that of ${^6_{\Lambda\Lambda}{\rm He}}$ for all absorption orbitals: in the case of the major 3D absorption their ratio is 1.08 for ORG and 1.96 for OCM. The dominant low momentum component of the d?α relative wave function favors the ${^5_{\Lambda\Lambda}{\rm H}}$ formation with a low Q value compared to the ${^6_{\Lambda\Lambda}{\rm He}}$ formation with a high Q value. We have also calculated momentum distributions of emitted particles, d and n, displaying continuum spectra for single-Λ hypernuclei, ${^4_{\Lambda}{\rm H}}$ and ${^5_{\Lambda}{\rm He}}$ , and line spectra for the ${^5_{\Lambda\Lambda}{\rm H}}$ and ${^6_{\Lambda\Lambda}{\rm He}}$ nuclei. Thus, our present theoretical analysis would be a significant contribution to experiments in the strangeness ?2 sector of hypernuclear physics.