Zein film as a novel natural biopolymer membrane in electrochemical detections

Permselective modifier films are very important in preparing highly sensitive electrochemical sensors. In this work, for the first time, the behavior of gold and glassy carbon electrodes coated with biocompatible zein film as a permselective membrane for the electrochemical detection of various compounds has been investigated. For this purpose, several electroactive cationic (methylene blue, brilliant green, and thionine) and anionic (potassium ferricyanide, alizarin red S, and riboflavin-5’-phosphate) compounds have been used as model. Atomic force microscopy (AFM) and scanning electron microscopy (SEM) showed that zein membranes prepared from casting solution containing 1% zein in ethanol/water have porous structures with high nanometric roughness. The capacitance values of electrical double layers of electrodes modified with zein film were very high for hydrophilic ions in comparison with hydrophobic ions. Point of zero charge pH (pH_pzc) of zein membrane was 4.8. The results of cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) as well as pH_pzc study indicated that zein permselective membrane acts as ion exchanger film for selected cationic compounds with fast electrochemical kinetics responses in aqueous solution (pH=7). This behavior was confirmed by circulating solutions containing model compounds from homemade continuous cell equipped with polyamide membranes modified with zein film.

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Preparation and characterization of Cu (II) supported on poly(8‐hydroxyquinoline‐p‐styrene sulphonate) and its application as catalyst for the synthesis of hexahydroquinolines

Cu ( II ) supported on poly(8‐hydroxyquinoline‐p‐styrenesulfonate) (Cu ( II )@PHQSS) was prepared and fully characterized by the different techniques including fourier transform infrared spectroscopy (FT‐IR), ¹H NMR, ¹³C NMR, thermal gravimetric analysis (TGA), differential thermal gravimetric (DTG), differential thermal analysis (DTA), scanning electron microscope (SEM) and energy dispersive X‐ray analysis (EDS). Afterward, the Cu ( II )@PHQSS as nanostructured catalyst was used as catalyst for the synthesis of hexahydroquinolines.     

Theoretical investigation of effects of local cooling of a nozzle divergent section for controlling condensation shock in a supersonic two-phase flow of steam

In supersonic adiabatic two-phase flows of steam, under the influence of supersonic acceleration, the fluid loses its equilibrium conditions and becomes supersaturated. Following this condition and to restore the fluid to equilibrium, micro droplets of water form in the absence of any surface or foreign particles. This phenomenon is called homogeneous nucleation and the formed minute small droplets grow along the fluid flow path. The formation of these droplets and their growth causes the release of the latent heat of evaporation to the gas phase particularly in the nucleation region, and results in an increase in the flow pressure which is called the condensation shock. In this paper, and in continuation of the series of papers by the authors, in addition to analytically solving the adiabatic gas-liquid supersonic flow of steam in a convergent-divergent channel, a novel solution to controlling the undesired effects of this pressure rise (condensation shock) is presented. In the proposed method, with the help of cooling the divergent section of the nozzle, the analytical model for the 1D non-adiabatic two-phase steam flows is further developed which shows considerable decrease in the intensity of the formed condensation shock. Also the growth rate of the formed droplets due to the cooling of the steam flow has higher importance than the nucleation itself.     

Synthesis of diaryl sulfides via nickel ferrite‐catalysed C─S bond formation in green media

NiFe₂O₄ magnetic nanoparticles (MNPs) were synthesized, characterized and applied as an air‐stable, inexpensive and magnetically separable nanocatalyst for the synthesis of structurally diverse sulfides. Efficient methodologies were developed for the synthesis of unsymmetric diaryl sulfides via odourless and one‐pot reactions of triphenyltin chloride/S₈ or arylboronic acid/S₈ as thiolating agents with aryl halides or nitroarenes as starting materials in the presence of base (K₂CO₃ or NaOH) and NiFe₂O₄ MNPs as a catalyst in water or poly (ethylene glycol) as solvent at 80–110 °C. Free from ligand and the unpleasant smell of thiols and with the use of magnetically reusable nanocatalyst, green solvents and commercially available and cheap sulfur source and starting materials, these methods are more eco‐friendly and practical than available protocols for the synthesis of sulfides.     

Copper-based metal–organic framework decorated by CuO hair-like nanostructures: Electrocatalyst for oxygen evolution reaction

We report a Cu-based metal–organic framework (MOF) decorated by CuO nanostructures as an efficient catalyst for the oxygen evolution reaction (OER). MIL-53(Cu) was synthesized by a hydrothermal approach using 1,4-bezenedicarboxylic acid as organic precursor and further annealed at 300°C to form CuO nanostructures on its surface. The produced electrocatalyst, CuO@MIL-53(Cu), was characterized using various techniques. Under alkaline conditions, the developed electrocatalyst exhibited an overpotential of 801 and 336 mV versus RHE at 10 and 1 mA cm⁻², respectively. The reproducibility of the catalytic performance was validated using several electrodes. It was confirmed that the CuO hair-like nanostructures grown on MIL-53(Cu) using thermal treatment exhibit high OER activity, good kinetics and durability. CuO@MIL-53(Cu) is an economic noble-metal-free OER electrocatalyst. It has potential for application as anode material for sustainable energy technologies like batteries, fuel cells and water electrolysis.     

Promising new catalytic properties of a Co (II)-carboxamide complex and its derived Co3O4 nanoparticles for the Mizoroki-Heck and the Epoxidation reactions

The new Co(II) - carboxamide complex ( 1 ) and Co₃O₄ nanoparticles ( 2 ), by way of thermal decomposition of ( 1 ) have been efficiently synthesised in the environment-friendly. X-ray diffraction reveals a slightly distorted octahedral coordination of cobalt (four nitrogens and two oxygens) in ( 1 ) and regular octahedral or tetrahedral ones (oxygens only) in ( 2 ). The investigation of ( 1 ) and ( 2 ) in the Mizoroki-Heck and epoxidation of alkens reactions showed them both to be powerful, green and inexpensive catalysts.     

A Highly Accurate Refractive Index Sensor with Two Operation Modes Based on Photonic Crystal Ring Resonator

A 2D hole‐type hexagonal lattice photonic crystal is utilized, herein, to detect the refractive index change of the material infiltrated into the designed circular sensing area which also resembles a ring resonator. The accuracy of the detection process is enhanced considering the simultaneous shift of the resonance wavelengths and the intensity modulation which occur in two separate spectral regions. The presented structure has the ability to detect liquids, material concentrations in fluids and gases having refractive indices in the range of n = 1–2 with sensitivity and quality factor of 61 nm/RIU and 3000, respectively, for resonance‐wavelength‐shift‐based operation. The detection range of n = 1–1.4 with the sensitivity of S = 0.69 NI/RIU is achieved for the intensity‐based measurement and the results show good linearity in the operating range.     

Novel marine-based gold nanocatalyst in solvent-free synthesis of polyhydroquinoline derivatives: Green and sustainable protocol

We report an ecofriendly synthetic approach for the fabrication of biogenic gold nanoparticles (AuNPs) using electron-rich sea cucumber extract as a bio-reductant and stabilizing agent in reducing gold cations into AuNPs at the optimal conditions. The produced AuNPs are spherical in shape with an average particle size of 11 ± 1.5 nm in transmission electron microscopy (TEM) and exhibited a crystal structure of face-centered cubic in X-ray diffraction (XRD) analyses. Our results indicated that bioinspired AuNPs demonstrate superior catalytic activity in the safe and facile one-pot synthesis of polyhydroquinoline derivatives under solvent-free reaction conditions. This green route encompasses multiple benefits including highly recyclable bioinspired catalyst (5 cycles), short reaction times, convenient workout, high to excellent product yields (82%–97%), and nonhazardous conditions.     

Phyto-synthesis of silver nanoparticles using aerial extract of Salvia leriifolia Benth and evaluation of their antibacterial and photo-catalytic properties

Research on Chemical Intermediates - We have synthesized silver nanoparticles (Ag-NPs) via a simple and eco-friendly method through the utilization of aqueous aerial parts of Salvia leriifolia...