Ultrasound-assisted photochemical oxidation of unsymmetrically substituted 1,4-dihydropyridines

The combination of ultrasound and photochemistry has been used for the oxidation of unsymmetrical 1,4-dihydropyridines to the pyridine derivatives. An ultrasonic probe of 24 kHz frequency and a Hg-lamp of 100 W have been used for this study. The effect of parameters such as ultrasonic intensity, the presence of oxygen and argon atmospheres and also the separate usage of one of these irradiation sources have been studied. Whereas sonication of these compounds alone did not result in the oxidation of them, the use of ultrasound increases the rate of photo-oxidation. The presence of oxygen decreases or increases the rate of reaction, depending on the type of excited state of 1,4-dihydropyridines involved in the reaction.     

Cascade synthesis of fused polycyclic dihydropyridines by Ni–Zn–Fe hydrotalcite (HT) immobilized on silica-coated magnetite as magnetically reusable nanocatalyst

Research on Chemical Intermediates - An efficient ecofriendly approach has been developed for one-pot multicomponent synthesis of fused polycyclic dihydropyridine (DHP) derivatives. Tandem...     

Highly efficient synthesis of dicoumarols and xanthene derivatives in presence of Brønsted–Lewis acidic ionic liquids catalyst

A series of metal chloride-based acidic ionic liquids have been prepared and used as an efficient catalyst in one-pot multicomponent synthesis of biscoumarins and substituted xanthenes derivatives under solvent-free conditions. Among the acidic ionic liquids, N-methylpyrrolidonium zinc chloride (Hnmp/ZnCl₃)-based Brønsted–Lewis acidic ionic liquids were found to be an effective and recyclable catalyst for a one-pot synthesis of biscoumarins through the domino Knoevenagel–Michael reaction of a variety of aldehydes with 4-hydroxycoumarin in short reaction times. The reactions which occur under relatively mild conditions afforded the biscoumarin derivatives employing a very low loading of catalyst in satisfactory isolated yields and high purity after simple work-up. The Brønsted–Lewis acidic ionic liquid catalyst was reused four times without any variation in yield.     

Influence of molar mass of polymer on the solvent activity for binary system of poly N-vinylcaprolactam and water

The water activity in aqueous solution of poly N-vinyl caprolactam with different molecular weights is measured by isopiestic method at T = 308.15 K. The results show that water activity and vapour pressure of poly N-vinylcaprolactam solution increases with increasing the molecular weight. The Flory-Huggins model, the modified Flory-Huggins model and Freed Flory-Huggins equation + NRTL model are used for correlation of the experimental solvent activity. It is found that the Freed Flory-Huggins + NRTL model is better than the others.     

Wound healing improvement by curcumin‐loaded electrospun nanofibers and BFP‐MSCs as a bioactive dressing

Wound healing, one of the most complex processes of the body involving the cooperation of several important biomolecules and pathways, is one of the major therapeutic and economic issues in regenerative medicine. The present study aimed to introduce a novel electrospun curcumin (Cur)‐incorporated chitosan/polyvinyl alcohol/carbopol/polycaprolactone nanofibrous composite for concurrent delivery of the buccal fat pad‐derived mesenchymal stem cells (BFP‐MSCs) and Cur to a full‐thickness wound on the mouse model. Scaffolds were characterized structurally using scanning electron microscopy (SEM), fluorescence microscopy imaging and Fourier‐transform infrared spectroscopy, and toxicity of the scaffolds was also evaluated after BFP‐MSC seeding by SEM imaging and 3‐(4,5 dimethyiazol‐2‐1)‐2‐5‐diphenyl tetrazolium bromide (MTT) assay. Then, its influence on the wound‐healing process was investigated as a wound dressing for a full‐thickness skin defect in mouse model. Results demonstrated that the designed composite scaffolds have the capability for cell seeding and support their growth and proliferation. Macroscopic and histopathological characteristics were evaluated at the end of the 7 and 14 days after surgery, and their results showed that our designed scaffold groups accelerated the wound‐healing process compared with the control group. Among those, scaffold/Cur, scaffold/Cur/BFP‐MSC and scaffold/BFP‐MSC groups demonstrated more wound repair efficacy. These results indicated that the combined grafts can be used to improve the wound‐healing process, and therefore, the electrospun nanofibers presented in this study, Cur and BFP‐MSC together, were demonstrated to have promising potential for wound‐dressing applications.     

A theoretical study of 1:1 and 1:2 complexes of acetylene with nitrosyl hydride

Ab initio calculations at MP2 computational level using aug-cc-pVTZ basis set were used to analyze the interactions between 1:1 and 1:2 complexes of acetylene and nitrosyl hydride. The structures obtained have been analyzed with the atoms in molecules and the density functional theory–symmetry adapted perturbation theory methodologies. Four minima were located on the potential energy surface of the 1:1 complex. Twenty-four different structures have been obtained for the 1:2 complexes. Five types of interactions are observed, CH···O, CH···N, NH···π hydrogen bonds and orthogonal interactions between the π clouds of triple bond, or the lone pair of oxygen with the electron-deficient region of the nitrogen atom. Stabilization energies of the 1:1 and 1:2 clusters including basis set superposition error and ZPE are in the range 3–8 and 6–17 kJ mol⁻¹ at MP2/aug-cc-pVTZ computational level, respectively. Blue shift of NH bond upon complex formation in the ranges between 18–30 and 20–96 cm⁻¹ is predicted for 1:1 and 1:2 clusters, respectively. The total nonadditive energy in the 1:2 cluster, calculated as the sum of the supermolecular nonadditive MP2 energy and the three-body dispersion energy, presents values between −1.48 and 1.20 kJ mol⁻¹.     

(Surfactant + polymer) interaction parameter studied by (liquid + liquid) equilibrium data of quaternary aqueous solution containing surfactant,polymer, and salt

(Liquid + liquid) equilibrium (LLE) data of quaternary aqueous system containing polyoxyethylene (20) cetyl ether (with abbreviation name Brij 58, non-ionic surfactant), diammonium hydrogen phosphate, and poly ethylene glycol (PEG) with three molar masses {M_W = (1000, 6000, and 35,000) g · mol^?1} have been determined experimentally at T = 313.15 K.Furthermore, the Flory–Huggins theory with two electrostatic terms (Debye–Hückel and Pitzer–Debye–Hückel equations) have been used to calculate the phase behavior of the quaternary systems and (surfactant + polymer) interaction parameter as well as interaction parameters between other species. Temperature dependency of the parameters of the Flory–Huggins theory has been obtained.Also an effort have been done to show that addition of PEG as well as increasing the temperature can shift the binodal curves of the ternary aqueous system containing surfactant and salt to lower mole fraction of salt. Also the effect of polymer molar mass on the binodal diagram displacement has been discussed.     

Temperature effects on spreading of water nano‐droplet on poly(methyl methacrylate): A molecular dynamics simulation study

In this article, the effect of temperature on the spreading behavior of a water nano‐droplet on poly(methyl methacrylate) substrate is investigated. The contact angle analysis illustrates that the spreading process occurs in a stage‐like manner and the increase in temperature causes a regime change from partial to total wetting. The interaction energy distributions show that there exist sites on the surface which could trap water molecules and provide a better path for other molecules to overcome the asperities. Estimations of the coefficients of self‐diffusivity suggest that temperature has a major effect in the reorientation stage, which results in the formation of the interfacial layer. In the second stage of spreading, temperature affects the process by providing sufficient energy for water molecules to overcome the interactions with the substrate. Therefore, this stage is controlled by the movement of water molecules on the surface and is highly influenced by their interaction with the surface asperities, strong interaction sites, and the carbonyl groups. © 2017 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2017 , 55, 1532–1541     

A Modified Quantum Search Algorithm

We show that by adding a workspace qubit to Ahmed Younes, et al. algorithm (Younes et al. AIP Conf. Proc. 734:171, 2004, 2008), and applying newly defined partial diffusion operators on subsystems, the algorithm’s performance is improved. We consider an unstructured list of N items and M matches, 1 ≤ M ≤ N.