Electrodeposition of Ag nanoparticles on graphenized pencil lead electrode as a sensitive and low-cost sensor for iodate determination

In this study, a simple, sensitive and low-cost iodate electrochemical sensor based on graphenized pencil lead electrode (GPLE) modified with Ag nanoparticles (AgNPs) was presented. The GPLE was simply prepared via electrochemical exfoliation of pencil lead electrode (PLE) by applying an optimized potential in acidic media. Afterward, silver nanoparticles were electrochemically deposited on the surface of GPLE using chronoamperometry technique. The fabricated electrode was carefully characterized by X-ray powder diffraction (XRD) and scanning electron microscopy (SEM) techniques. Electrochemical behavior and also the electrocatalytic performance of the modified electrode toward the reduction of iodate were studied in details using cyclic voltammetry (CV) and differential pulse voltammetry (DPV) techniques. The fabricated sensor responds efficiently to iodate over the concentration range of 0.05 to 75 mM with a detection limit of 0.017 mM and sensitivity of 0.26 µA µM^?1 cm^?2. Remarkably enhanced electrocatalytic performance of the modified electrode was ascribed to the synergistic effect of graphene-like nanostructures with high surface to volume ratio, excellent conductivity and also the excessive electrocatalytic behavior of silver nanoparticles. The modified electrode was successfully employed for the determination of iodate in table and sea salt samples.     

Air-assisted in situ deep eutectic solvent decomposition followed by the solidification of floating organic droplets-liquid-liquid microextraction method for extraction of azole antifungal drugs in biological samples prior to high-performance liquid chromatography

A free dispersive method, air-assisted in situ deep eutectic solvent decomposition followed by the solidification of floating organic droplets liquid-liquid microextraction was indicated in this study. This technique was utilized to simultaneously ascertain some azole antifungal drugs prior to high-performance liquid chromatography. In this research, a quasi-hydrophobic deep eutectic solvent was formed from tetrabutylammonium bromide and 1-dodecanol as an organic solvent at a 1:2 molar ratio. The synthesized deep decomposition in the sample solution caused in situ dispersion of extraction solvent and analytes. Air-assisted enhanced a dispersion condition in the sample solution. 1-Dodecanol as a green option was replaced with typical extraction solvents providing the advantages of a suitable freezing point near room temperature and low density. The effect of important analytical parameters on the extraction recovery of analytes was assessed. Under these optimal conditions, the limits of detection and the limits of quantitation determined were in the range of 0.5–2.8 and 1.5–9 μg/L, for water, urine and plasma samples, respectively. The intra-day and inter-day relative standard deviations (n = 5) were calculated to be 2.9–4.6 and 4.2–8.9%, respectively. The results represented the effectiveness of the developed method for the extraction and determination of analytes in biological samples.     

Solid State Synthesis and Characterization of Zinc Oxide (ZnO) Microflakes by [Bis(acetylacetonato)zinc(II)] and Sodium Hydroxide at Room Temperature

A novel and simple one-step solid state reaction in the presence of a suitable surfactant, sodium dodecyl sulfate (SDS), and a novel precursor, [bis(acetylacetonato)zinc(II)]; [Zn(acac)₂]; has been developed to synthesize uniform zinc oxide microflakes with an average thickness of 0.3–2.4 μm. In the absence of SDS the product samples contained microrods. The formation of zinc oxide microflakes depends on the molar ratio of Zn(II)/SDS and the experimental procedure. The products were characterized by X-ray diffraction, photoluminescence spectroscopy, FT-IR spectroscopy, surface area, scanning electron microscopy and transmission electron microscopy to depict the phase and morphology. The synthesized ZnO microflakes have a hexagonal zincite structure.     

Application of perforated sheets to improve the efficiency of reactive profiled noise barriers

The scope of this paper is to study the performance of noise barriers treated with different diffusers with/without a perforated sheet. We investigated the barrier insertion loss using a 2D boundary element method (BEM). To obtain a better depth sequence, a Random Sequence Diffuser (RSD) was designed. The results clearly showed that employing a "RSD" instead of the most popular Schroeder diffusers (Quadratic Residue Diffuser and Primitive Root Diffuser) increased the acoustic performance. We also found that the diffuser performance improved by treating the diffuser with perforated sheets either on the top surface or inside the wells. The addition of these perforated sheets inside the "RSD" (barrier model "RPI2") improved the performance by 3.59 dB (A).     

Synthesis of 2-amino-3-cyano 4-<Emphasis Type="Italic">H</Emphasis>-chromenes containing quinoline in water: computational study on substituent effects

An efficient, high yielding and environmentally benign strategy to the synthesis of new 2-amino-3-cyano-4-H-chromene derivatives, via one-pot three-component reaction involving malononitrile, various α- or β-naphthol and appropriate aromatic aldehydes including 2-chloroquinoline-3-carbaldehydes in the presence of morpholine in water, was achieved. During the development of the synthesis five new chromene derivatives were fruitfully synthesized. It was found that employing this approach, aromatic aldehydes bearing electron-withdrawing groups give higher yields of the corresponding products in shorter reaction times. This observation was in agreement with topological analysis of calculated electron density functions using density functional theory and quantum theory of atoms in molecules approaches.     

A new force field for the adsorption of H2, O2, N2, CO,H2O,and H2S gases on alkali doped carbon nanotubes

The main goal of this work is the generation of a new force field data set to the interaction of several gases such as H₂, O₂, N₂, CO, H₂O, and H₂S with alkali cation-doped carbon nanotubes (CNTs) using ab initio calculations at the MP2(full)/6-311++G(d,p) level of theory. Different alkali cations including Li⁺, Na⁺_, K⁺ and Cs⁺ were used to dope in the CNT. The calculated potential energy curve for the interaction of each gas molecule with each alkali cation-doped CNTs was fitted to an analytical potential function to obtain the parameters of the potential function. A modified Morse potential function was selected for the fitting in which the electrostatic interactions has been accounted by adding the β/r term to the Morse potential. The accuracy of the calculated force field was checked via Grand Canonical Monte Carlo (GCMC) simulation of the H₂ adsorption on Li-doped graphite and Li-doped CNT. The results of these simulations were compared with the experimental measurements and the closeness of the simulation results with the experimental data indicated the accuracy of the proposed force field. The main merit of this work is the derivation of a specific force field for interaction of each of six gases with four alkali cation-doped CNT, which can be used in molecular simulation of these 24 of systems. The simulation results showed the increase of the H₂ adsorption capacity of nanotube and graphite up to 50% and 10%, respectively, due to the insertion of Li ions.     

Simple sonochemical synthesis and characterization of HgSe nanoparticles

Mercury selenide (HgSe) nanostructures were synthesized via a sonochemical method based on the reaction between HgCl(2), SeCl(4) and hydrazine hydrate (N(2)H(4)·H(2)O) in water, in presence of various capping agents. The effects of preparation parameters such as: the kind of capping agent and its amount, ultrasonic power, reaction time and temperature were investigated. It was found that morphology, particle size and phase of the products could be greatly affected by these parameters. HgSe nanostructures were characterized by X-ray powder diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), photoluminescence spectroscopy (PL) and X-ray energy dispersive spectroscopy (EDS).     

Synthesis of new substituted cylopentenone derivatives via a one-pot three-component reaction between arylglyoxals,acetylacetone, and amines in aqueous media

An efficient one-pot method for the synthesis of new substituted cylopentenone derivatives is described via reaction of arylglyoxals and acetylacetone with aliphatic amines. This reaction was carried out in aqueous media in the absence of any catalyst or promoter to produce substituted cylopentenone in high yield.     

The effect of curvature of Li-doped polycyclic hydrocarbon on its interaction energy with H<Subscript>2</Subscript> and H<Subscript>2</Subscript>O: DF-SAPT (DFT) calculation

In this work, the interaction of three Li⁺-doped polycyclic hydrocarbons (Li⁺-DPH) with H₂ and H₂O was calculated to investigate the effect of curvature of substrate on the interaction energy (E_int). For this purpose, the E_int and its decomposed energy components (electrostatic (E_elec), exchange (E_exch), induction (E_ind), and dispersion energy (E_disp)) were calculated using DF-SAPT (DFT) methodology for the selected systems (Li⁺-(3,3) carbon nanotube (Li⁺-CNT33), Li⁺-(6,6) carbon nanotube (Li⁺-CNT66), and Li⁺-graphene). According to the results, E_int does not change significantly with curvature for the interaction between both H₂ and H₂O gases and the selected Li⁺-DPH. Since the variation of the E_int with the curvature of Li⁺-DPH is not significant, the selection of a planar Li⁺-DPH is a trustworthy model to develop a general force field for describing the interaction between a Li⁺-DPH and adsorbed gases. The results reveal that, in the case of the H₂, the components E_elect, E_exch, E_ind, and E_disp have shown a decreasing trend with Li⁺-DPH’s curvature decrement. However, for the H₂O, E_elect, E_exch, and E_ind decrease from the Li⁺-CNT33 to the Li⁺-CNT66 while they increase from the Li⁺-CNT66 to the Li⁺-graphene. In this case, the E_disp increases with a decrease of the curvature of Li⁺-DPH. Finally, it can be seen that although the variation of the E_int with the curvature of Li⁺-DPH is not significant, the variation trend of the interaction energy components and the amount of variation depend on the gas molecule and in some cases are not negligible.     

Synthesis of new indolylpyrrole derivatives via a four-component domino reaction between arylglyoxals,acetylacetone, indole and aliphatic amines in aqueous media

A novel synthesis of indolylpyrrole derivatives is described by a four-component domino reaction between arylglyoxals, acetylacetone, indole and aliphatic amines in water as solvent at 60?°C without using any catalyst or promoter. The FT-IR, ¹H NMR, ¹³C NMR spectral and elemental analysis confirm the structures of the products.