Synthesis and Characterization of Melamine Formaldehyde Resins for Decorative Paper Applications

Melamine‐formaldehyde (MF) resins of improved environmental compatibility were synthesized at different molar ratios, temperature and pH. Five molar ratios of melamine and formaldehyde: 35:65, 36.5:63.5, 38.3:61.7, 41.1:58.9 and 42.4:58.6 were used to synthesize the corresponding resins. The prepared samples were characterized by using molecular weight determination viscometery, field emission scanning electron microscopy and thermogravimetric analysis. It was noticed that the solid content in the resin increases with an increase in pH. The maximum percentage of the solid content (51 %) was obtained for pH of 8.5 and temperature range of 95–98 ^oC. The refractive index of the final product was found increasing with an increase of melamine concentration in the resin. A similar trend was noticed in molecular weight of the resins with an increase in monomer yield. The maximum molecular weight of 114218 was obtained from the sample synthesized with MF molar ratio of 42.4:58.6.     

Synthesis,characterization, and antioxidant and anticholinesterase activities of pyrazolo derivatives

Twenty-four pyrazolo derivatives (1–4)(a-f) were synthesized and characterized by FTIR, ¹H, and ¹³C NMR (Nuclear Magnetic Resonance), and elemental analysis. The synthesized compounds were also investigated for their antioxidant and anticholinesterase activities. The compounds (3–4)(a-f) carrying morpholine ring were more active than the piperidinyl containing compounds (1–2)(a-f) in both activities. The compound 4f showed higher activity in both assays as compared with the others. Additionally, the anticholinesterase activity test provided higher values than the galantamine in the BChE assay. Therefore, compound 4f can be used as anticholinesterase agent and/or anticholinesterase assay standard.     

Synthesis,crystal structure,antibacterial, cytotoxic,and anticancer activities of new Pd(II) complexes of tri-p-tolyl phosphine with thiones

Russian Journal of General Chemistry - Four Pd(II) complexes of general formula [Pd(L1)2(L2)2], where L1 = pyridine-2(1H)-thione, pyrimidine-2(1H)-thione, pyridine-4(1H)-thione, and...     

Ambient Acoustic Energy Harvesting using Two Connected Resonators with Piezoelement for Wireless Distributed Sensor Network

Acoustical Physics - In this article, an acoustic energy harvester (AEH) is conceptualized, designed, fabricated and tested. The developed AEH (DAEH) consists of two Helmholtz cavities (HCs) and a...     

Iron(III) porphyrin catalyzed ionic liquid mediated polymerization of methylmethacrylate

A novel application of iron(III)porphyrin catalyst, 5,10,15,20 ? tetrakis ? (2′,6′‐dichlorophenyl)porphyrinatoiron(III) chloride is reported for the reaction of methyl methacrylate with hydrogen peroxide in imidazolium ionic liquids at ambient temperature. The reaction furnished polymethyl methacrylate in 75–94% yields. The yield of the polymer was optimized upon changing the reaction media, ratio of catalyst, oxidant and substrate, reaction time and quenchers. The polymethyl methacrylate was secured as highly stereoregular with predominantly syndiotactic sequences as analyzed with the aid of NMR (¹H and ¹³C) and infrared spectroscopy. Besides, the number‐average molecular weights (Mn) were attained in the range of 15,000 to 55,000 with narrow polydispersity (~1.1–1.9) as calculated using gel permeable chromatography (GPC).     

Synthesis,crystal structure,DFT calculations,molecular docking study and Hirshfeld surface analysis of alkoxido-bridged dinuclear iron(III) complex

Research on Chemical Intermediates - Reaction of FeCl2·4H2O, NaN3 and N,N′-bis(2-hydroxyethyl)-ethylenediamine (heenH2) in a CH3CN/CH2Cl2 solution resulted in a dinuclear complex,...     

ZnO-Templated Selenized and Phosphorized Cobalt-Nickel Oxide Microcubes as Rapid Alkaline Water Oxidation Electrocatalysts

Oxygen electrocatalysis is of remarkable significance for electrochemical energy storage and conversion technologies, together with fuel cells, metal-air batteries, and water splitting devices. Substituting noble metal-based electrocatalysts by decidedly effective and low-cost metal-based oxygen electrocatalysts is imperative for the commercial application of these technologies. Herein, a novel strategy is presented to fabricate selenized and phosphorized porous cobalt-nickel oxide microcubes by using a sacrificial ZnO spherical template and the resulting microcubes are employed as an oxygen evolution reaction (OER) electrocatalyst. The selenized samples manifest desirable and robust OER performance, with comparable overpotential at 10 mA cm⁻² (312 mV) as RuO₂ (308 mV) and better activity when the current reaches 13.7 mA cm⁻². The phosphorized samples exhibit core–shell structure with low-crystalline oxides inside amorphous phosphides, which ensures superior activity than RuO₂ with the same overpotential (at 10 mA cm⁻²) yet lower Tafel slope. Such a surface doping method possibly will provide inspiration for engineering electrocatalysts applied in water oxidation.     

Combined effects of heat and chemical reactions on the peristaltic flow of carreau fluid model in a diverging tube

The study of peristaltic flow of a Carreau fluid in a non‐uniform tube under the consideration of long wavelength in the presence of heat and mass transfer is presented. The flow is investigated in a wave frame of reference moving with velocity of the wave c. Two types of analytical solutions have been evaluated (i) perturbation method (ii) homotopy analysis method for velocity, temperature and concentration field. Numerical integration have been used to obtain the graphical results for pressure rise and frictional forces. The effects of various emerging parameters are investigated for five different peristaltic waves. Copyright © 2010 John Wiley & Sons, Ltd.     

Exact and numerical simulation of peristaltic flow of a non‐Newtonian fluid with inclined magnetic field in an endoscope

In the present article, we have studied the effects of inclined magnetic field on the peristaltic flow of Jeffrey fluid through the gap between two coaxial inclined tubes. The inner tube is rigid, whereas the outer tube has sinusoidal wave traveling down its wall. The governing equations are simplified using long wave length and low Reynolds number approximations. Exact and numerical solutions have been derived for velocity profile. The expressions for pressure rise and friction force are calculated using numerical integration. Graphical results and trapping phenomenon is presented at the end of the article to see the physical behavior of different parameters. Copyright © 2010 John Wiley & Sons, Ltd.     

Gold catalysis in organic transformations: A review

This review updates the explosive development of gold catalysis for organic transformation focusing on the current literature over last 3 years. Recent investigations have shown that gold catalysis provides catalytically active systems, whereas selectivity and reusability are advantages over noncatalyzed organic transformations. The collected literature is focusing for new organic reactions and synthetic methodologies. Gold can also be suggested for green processes dedicated to fine chemicals, pharmaceuticals, and the food industry due to its recognized biocompatibility. The current review is focused on new methods in the organic synthesis that could be of interest in the wide area of organic chemistry for developing new catalytic pathways.