Green Recyclable CuO‐CeO2 Nanocomposite Catalyzed Amination of Aryl Halides with Aqueous Ammonia in Water

CuO‐CeO₂ nanocomposite as a green recyclable catalyst, catalyzed amination of aryl halides with aqueous ammonia in water. This catalyst can be easily recovered by simple filtration and recycled up to 5 consecutive runs with consistent activity. The procedure provides some advantages such as simple work‐up, clean procedure, relatively short reaction times and high yields of the products.     

Novel Metal Oxide of CuO-ZnO Nanocatalyst Efficiently Catalyzed the Synthesis of 2-Amino-4H-chromenes in Water

Novel metal oxide of CuO-ZnO nanocatalyst was prepared by a coprecipitation method and characterized by x-ray diffusion, Brunauer–Emmett–Teller surface area, scanning electron microscopy, transmission electron microscopy, and energy dispersive spectroscopy (EDS) analysis. The catalyst is efficient for the synthesis of 2-amino-4H-chromenes by one-pot condensation of aromatic aldehydes, hydroxynaphthalene derivatives, and malononitrile in water at reflux conditions. Moreover, CuO-ZnO nanocatalyst can be recycled up six times without any significant loss of its catalytic activity.     

A spectroelectrochemical study of conducting pyrrole-N-methylpyrrole copolymers in nonaqueous solution

Conducting poly(pyrrole-N-methylpyrrole) (P(Py-NMPy)) was electrochemically synthesized on a gold electrode in a lithium perchlorate-containing acetonitrile electrolyte solution and compared with polypyrrole (PPy) and poly(N-methylpyrrole) (PNMPy) prepared under the same conditions. The obtained polymers were characterized with cyclic voltammetry, in situ resistance measurements, in situ UV–vis spectroscopy, FTIR spectroscopy, and scanning electron microscopy. The onset potentials for pyrrole and N-methylpyrrole monomer oxidation differ by about 0.1 V. Nucleation processes initiated by the radical cations are followed by growth of nuclei into continuous films. The oxidation and reduction peaks for the P(Py-NMPy) copolymer synthesized at 1:1 M concentration ratio of the comonomers are between those of PPy and PNMPy. A decreased [Py]/[NMPy] comonomer concentration ratio yields in the copolymers shifts of peak potentials to more positive values. The in situ resistance of copolymers measured from ?0.20 to 0.90 V vs. Ag/AgCl decreased with increasing [Py]/[NMPy] concentration ratio. In situ UV–vis and ex situ FTIR spectra of copolymers show spectroscopic behavior intermediate between those of the homopolymers. Scanning electron microscopy micrographs of the samples show fundamental differences between the morphology of the homo- and copolymers.     

Selective Adsorption and Determination of Hexavalent Chromium in Water Samples by Chemically Modified Activated Carbon with Tris(hydroxymethyl)aminomethane

This study introduces a sensitive and simple method for selective adsorption of hexavalent chromium, Cr(VI), from water samples prior to its determination by inductively coupled plasma optical emission spectrometry (ICP-OES). The method utilized activated carbon modified with tris(hydroxymethyl)aminomethane (AC-TRIS) as an adsorbent. Surface properties of the new chemically modified AC-TRIS phase were confirmed by Fourier transform infrared (FTIR) spectroscopy. Seven metal ions, including Co(II), Cu(II), Ni(II), Pb(II), Cr(III), Cr(VI), and Fe(III) were evaluated and determined at different pH values (1.0–8.0), except for Fe(III) at pH values (1.0–4.0). Based on the results of the effect of pH on adsorption of these metal ions on AC-TRIS, Cr(VI) was selected for the study of other parameters controlling its maximum uptake on AC-TRIS under batch conditions and at the optimum pH value 1.0. The maximum static adsorption capacity of Cr(VI) onto the AC-TRIS was found to be 43.30 mg g^?1 at this pH and after 1 hour contact time. The adsorption data of Cr(VI) were modeled using both Langmuir and Freundlich classical adsorption isotherms. Results demonstrated that the adsorption of Cr(VI) onto AC-TRIS followed a pseudo second-order kinetic model. In addition, the efficiency of this methodology was confirmed by applying it to real environmental water samples.     

A highly sensitive RP-HPLC-fluorescence method to study aldehyde oxidase activity

Aldehyde oxidase is a widely distributed enzyme that is involved in the metabolism of an extensive range of aldehydes and N-heterocyclic compounds with physiological, pharmacological, and toxicological relevance. In the present study, a highly sensitive RP-HPLC-fluorescence method based on the oxidation of phenanthridine to phenanthridinone has been developed and validated to assay aldehyde oxidase activity in biological samples. Determination of phenanthridinone was achieved on a C18 column using 10 mmol/L phosphate buffer (pH 5.0) containing 0.1 mmol/L EDTA-acetonitrile (40 + 60, v/v) as the mobile phase. The fluorescence intensity of phenanthridinone was measured at 364 nm with excitation at 236 nm. The proposed method was precise, accurate, specific and rapid (analysis time, approximately 8 min) with a mean RSD of 2.54%. Peak responses were linear from 0.5 to 100 nmol/L, with an LOD of 0.125 nmol/L. The applicability of the method was demonstrated by measurement of aldehyde oxidase activity in rat liver, kidney, ovary, and heart fractions.     

A novel glycoconjugated N-acetylamino aldehyde hydrazone azo dye as chromogenic probe for cyanide detection in water

A new selective chemodosimeter probe of cyanide anions in aqueous media was developed by the introduction of a simple glyco-conjugated o-(carboxamido) aldehyde hydrazone into an azo dye as chemodosimeter that recognizes cyanide anions among other competing anions such as acetate, dihydrogen phosphate, fluoride through reversible covalent bonding. The sensing properties of the new materials were investigated in pure water and have demonstrated a very high selectivity toward the cyanide anions. The detection limit of the new chromogenic probe was measured to be 1.29 μM which is much lower than most recently reported chromogenic probes for cyanide determination.     

(Vapor + liquid) equilibrium properties of (ethane + ethanol) system at (295, 303, and 313) K

The (vapor + liquid) equilibrium data for binary system of (ethane + ethanol) at three temperatures (295, 303, and 313) K were measured using a designed pressure–volume–temperature (PVT) apparatus. A wide range of pressures, (1 to 5) MPa, were considered for the measurements. The phase composition, saturated density, and viscosity of liquid phase were measured for each pressure and temperature. The experimental (vapor + liquid) equilibrium data were compared with the modeling results obtained using the Peng–Robinson and Soave–Redlich–Kwong equations of state.     

Single granular activated carbon microextraction and graphite furnace atomic absorption spectrometry determination for trace amount of gold in aqueous and geological samples

A new and simple method was developed for preconcentration trace amount of gold in aqueous and mineral samples. The method was based on the sorption of gold on granular activated carbon (AC) in acidic medium (hydrochloric acid) and subsequently direct determination by graphite furnace atomic absorption spectrometry (GFAAS). A small particle of adsorbent was delivered to small volume of sample. After extraction, AC removed and analyzed directly by GFAAS. Several factors influencing the extraction efficiency, such as the hydrochloric acid concentration, sample volume and extraction time were studied as well as effect of potential interfering ions. The preconcentration factor 50 was obtained. The limit of detection (LOD) of gold in water and soil samples was 0.007 μg L^− 1 and 0.9 ng g^− 1, respectively. The proposed method was applied successfully to the determination of trace amount of gold in environmental and geological samples. In order to validate the developed method, two certified reference materials: Platinum Ore (SARM-7B) and Copper Ore Mill Heads (No. 330) were analyzed and the determined values obtained were in good agreement with the certified values and recovery was obtained in the range of 80-118%. The relative standard deviations (RSD) for the spiking levels of 0.5 μg L^− 1 in the real samples was 4%, (n = 15).     

Casimir force in presence of multi layer magnetodielectric slabs

By using the path-integral formalism, electromagnetic field in the presence of some linear, isotropic magnetodielectric slabs is quantized and related correlation functions are found. In the framework of path-integral techniques, Casimir force between two infinitely large, parallel and ideal conductors, with a different number of magnetodielectric slabs in between, is obtained by calculating the Green’s function corresponding to each geometry.