Synthesis of spiro[pyrazoloquinoline-oxindoles] and spiro[chromenopyrazolo-oxindoles] promoted by guanidine-functionalized magnetic Fe<Subscript>3</Subscript>O<Subscript>4</Subscript> nanoparticles

Magnetic nanoparticles (MNPs) Fe₃O₄-immobilized guanidine (Fe₃O₄ MNPs-guanidine) have been used as an efficient catalyst for the preparation of spiro[pyrazoloquinoline-oxindoles] and spiro[chromenopyrazolo-oxindoles] by four-component reactions of phenylhydrazine or hydrazine hydrate, isatins, ketoesters and naphthylamine or 2-naphthol under reflux condition in ethanol. This method provides several advantages including mild reaction conditions, the applicability to a wide range of substrates, the reusability of the catalyst and low catalyst loading.     

An implicit 2D hydrodynamic numerical model for free surface–subsurface coupled flow problems

A 2‐dimensional hydrodynamic finite volume model has been proposed for simultaneous simulation of free surface and saturated porous media. The governing equations of the former are 2‐dimensional averaged in a unit width of Navier‐Stokes, whereas that of the latter are Darcy law. An efficient, simple, and stable algorithm has been proposed to track the surface elevation in Cartesian coordinate system by which the water elevation in each computational column has been computed along with the other pressure unknowns simultaneously. The surface position has not been considered to remain in a specific layer so the number of cells in each column have been variably adjusted in accordance with the water surface elevation. Performance of the coupled model has been validated against a range of hydrodynamic problems including propagation of linear short wave, seepage test, tidal oscillation in a lagoon system, gravity current, and saltwater intrusion. Comparison between numerical results, analytical solutions, and experimental data demonstrates that the model represents well the interacting surface water and ground water flow and solute transport processes.     

Controlled and scalable torsional actuation of twisted nylon 6 fiber

Large‐scale torsional actuation occurs in twisted fibers and yarns as a result of volume change induced electrochemically, thermally, photonically, and other means. A quantitative relationship between torsional actuation (stroke and torque) and volume change is here introduced. The analysis is based on experimental investigation of the effects of fiber diameter and inserted twist on the torsional stroke and torque measured when heating and cooling nylon 6 fibers over the temperature range of 26–62 °C. The results show that the torsional stroke depends only on the amount of twist inserted into the fiber and is independent of fiber diameter. The torque generated is larger in fibers with more inserted twist and with larger diameters. These results are successfully modeled using a single‐helix approximation of the twisted fiber structure. © 2016 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2016 , 54, 1278–1286     

Developing Novel Fabrication and Optimisation Strategies on Aggregation-Induced Emission Nanoprobe/Polyvinyl Alcohol Hydrogels for Bio-Applications

The current study describes a new technology, effective for readily preparing a fluorescent (FL) nanoprobe-based on hyperbranched polymer (HB) and aggregation-induced emission (AIE) fluorogen with high brightness to ultimately develop FL hydrogels. We prepared the AIE nanoprobe using a microfluidic platform to mix hyperbranched polymers (HB, generations 2, 3, and 4) with AIE (TPE-2BA) under shear stress and different rotation speeds (0–5 K RPM) and explored the FL properties of the AIE nanoprobe. Our results reveal that the use of HB generation 4 exhibits 30-times higher FL intensity compared to the AIE alone and is significantly brighter and more stable compared to those that are prepared using HB generations 3 and 2. In contrast to traditional methods, which are expensive and time-consuming and involve polymerization and post-functionalization to develop FL hyperbranched molecules, our proposed method offers a one-step method to prepare an AIE-HB nanoprobe with excellent FL characteristics. We employed the nanoprobe to fabricate fluorescent injectable bioadhesive gel and a hydrogel microchip based on polyvinyl alcohol (PVA). The addition of borax (50 mM) to the PVA + AIE nanoprobe results in the development of an injectable bioadhesive fluorescent gel with the ability to control AIEgen release for 300 min. When borax concentration increases two times (100 mM), the adhesion stress is more than two times bigger (7.1 mN/mm²) compared to that of gel alone (3.4 mN/mm²). Excellent dimensional stability and cell viability of the fluorescent microchip, along with its enhanced mechanical properties, proposes its potential applications in mechanobiology and understanding the impact of microstructure in cell studies.     

Acet­amidoxime

The oxime of acet­amide, viz. N‐hydroxy­ethanimid­amide, C₂H₆N₂O, has a complex hydrogen‐bonding arrangement in its crystal structure, featuring one strong O—H⋯N hydrogen bond together with weaker hydrogen bonding involving the amide groups. Conjugation effects lead to atypical distances and angles.     

Magnetic carbon nanotube‐supported imidazolium cation‐based ionic liquid as a highly stable nanocatalyst for the synthesis of 2‐aminothiazoles

Magnetic carbon nanotube‐supported imidazolium ionic liquid (CNT‐Fe₃O₄‐IL) was synthesized and investigated using various characterization techniques, including Fourier transform infrared and Raman spectroscopies, X‐ray diffraction, vibrating sample magnetometry, scanning and transmission electron microscopies, and thermogravimetric and differential thermal analyses. In order to synthesize the CNT‐Fe₃O₄‐IL nanocomposites, Fe₃O₄‐decorated multi‐walled CNTs were modified with 1‐methyl‐3‐(3‐trimethoxysilylpropyl)‐1H‐imidazol‐3‐ium chloride. This catalytic system was found to be a highly stable, active, reusable and solid‐phase catalyst for the synthesis of 2‐aminothiazoles via the one‐pot reaction of ketone, thiourea and N‐bromosuccinimide under mild conditions. Immobilized magnetic ionic liquid catalysis combines the advantages of ionic liquid media with magnetic solid support nanomaterials which enables the application of nanotechnology and green chemistry in chemical processes. Copyright © 2016 John Wiley & Sons, Ltd.     

Stacking sequence optimization of composite plates for maximum fundamental frequency using particle swarm optimization algorithm

The paper illustrates the application of the particle swarm optimization (PSO) algorithm to the lay-up design of symmetrically laminated composite plates for maximization of fundamental frequency. The design variables are the fiber orientation angles, edge conditions and plate length/width ratios. The formulation is based on the classical laminated plate theory (CLPT), and the method of analysis is the semi-analytical finite strip approach which has been developed on the basis of full energy methods. The performance of the PSO is also compared with the simple genetic algorithm and shows the good efficiency of the PSO algorithm. To check the validity, the obtained results are compared with those available in the literature and some other stacking sequences, wherever possible.