Synthesis, Characterization, Photoluminescence and Photocatalytic Properties of CeO2 Nanoparticles by the Sonochemical Method

Uniform CeO₂ nanoparticles were synthesized via a facile sonochemical reaction between ceric ammonium nitrate and ammonia. Nanoparticles were synthesized via a surfactant free reaction at room temperature in solvent of water. Products were characterized using X-ray diffraction, scanning electron microscopy, photoluminescence (PL) spectroscopy, and energy dispersive X-ray analysis. The effect of different parameters such as precursor, power of pulsation, surfactant and reaction time on the morphology of the products was investigated. It was found that the as-obtained CeO₂ nanoparticles exhibit a strong PL peak at 381 nm at room temperature that can be ascribed to the high level transition in the CeO₂ semiconductor. The photocatalytic behavior of CeO₂ nanoparticles was evaluated using the degradation of a methyl orange aqueous solution under ultraviolet light irradiation. The results show that CeO₂ nanoparticles are promising materials with excellent performance in photocatalytic applications.     

An Efficient One‐pot Access to Substituted Dihydropyrrol‐2‐one Derivatives Using Sucrose as Natural,Biodegradable and Inexpensive Catalyst

An efficient and simple procedure for the synthesis of highly substituted dihydropyrrol‐2‐ones has been developed via one‐pot four‐component condensation of amines, dialkyl acetylenedicarboxyaltes and formaldehyde in the presence of sucrose as an organocatalyst. The salient advantages of this method are using a natural, biodegradable and commercial available catalyst, good yields, short reaction times, simple work‐up and lack of need for column chromatography.     

Numerical analysis of the drop impact onto a liquid film of non-linear viscoelastic fluids

Meccanica - This paper numerically analyzes the crown formation due to a plane two-dimensional drop impact onto a pre-existing film in a viscoelastic fluid. The finite volume method is applied to...     

Molecularly imprinted polymer based potentiometric sensor for the determination of hydroxyzine in tablets and biological fluids

Molecular imprinting is a useful technique for the preparation of functional materials with molecular recognition properties. In this work, a biomimetic potentiometric sensor, based on a non-covalent imprinted polymer, was fabricated for the recognition and determination of hydroxyzine in tablets and biological fluids. The molecularly imprinted polymer (MIP) was synthesized by precipitation polymerization, using hydroxyzine dihydrochloride as a template molecule, methacrylic acid (MAA) as a functional monomer and ethylene glycol dimethacrylat (EGDMA) as a cross-linking agent. The sensor showed a high selectivity and a sensitive response to the template in aqueous system. The MIP-modified electrode exhibited a Nernstian response (29.4 ± 1.0 mV decade⁻¹) in a wide concentration range of 1.0 × 10⁻⁶ to 1.0 × 10⁻¹ M with a lower detection limit of 7.0 × 10⁻⁷ M. The electrode demonstrated a response time of ∼15 s, a high performance and a satisfactory long-term stability (more than 5 months). The method has the requisite accuracy, sensitivity and precision to assay hydroxyzine in tablets and biological fluids.     

Ultrasonic assisted SPME coupled with GC and GC-MS using pencil lead as a fiber for monitoring the organic volatile impurities of ceftazidime

A simple, rapid, non-destructive, and in-situ method for the isolation and sampling of organic volatile impurities in Ceftazidime is developed using solid-phase microextraction (SPME). For the monitoring of the extracted compounds, gas chromatography (GC) and GC-mass spectrometry analyses are used. The effective factors such as nature of the fiber, SPME mode, extraction temperature, and ultrasonic assistance have been investigated and detailed here. Qualification studies reveal the existence of pyridine (as a degradation product of ceftazidime) and the residual solvents; acetone, methylene-chloride, and diethylamine are the main impurities in the studied pharmaceutical. External standard method is used for quantitative analysis. The % relative standard deviation values are below 10%, and the limits of detection for the detected solvents are 1.06, 0.98, 0.83, and 0.51 ppm, respectively. The proposed method is both accurate and linear and could be used in quality control of ceftazidime and also its stability investigations.     

Nickel-Zeolite modified carbon paste electrode as electrochemical sensor for hydrogen peroxide

In the present work, nickel-zeolite modified carbon paste electrode (Ni-ZMCPE) was prepared. The electrochemical behaviour of hydrogen peroxide at the surface of modified electrode was investigated by cyclic voltammetry and chronoamperometry in 0.1 M NaOH supporting electrolyte. The electrochemical characterization of Ni-ZMCPE exhibits redox behavior of Ni(III)/Ni(II) couple in alkaline medium. It has been shown that Ni-ZMCPE improves efficiency of the modified electrode toward hydrogen peroxide electrooxidation (It wasn’t remarkable different on ZMCPE and CPE in the presence and absence of hydrogen peroxide). Moreover, the effects of various parameters such as effect of different percents of Ni-Z to graphite, effect of pH and hydrogen peroxide concentration on the electrooxidation of hydrogen peroxide as well as stability of the Ni-ZMCPE have also been investigated. Under the selected conditions, the anodic peak current was linearly dependent on the concentration of hydrogen peroxide in the range 0.03–0.1 and 0.3–6 mM with amperometric method. The detection limit (S/N = 3) was also estimated to be 1 μM.     

Biomimetic electrochemical sensor based on molecularly imprinted polymer for dicloran pesticide determination in biological and environmental samples

Dicloran pesticide is used to inhibit the fungal spore germination for different crops. Because of the increasing application of pesticides, reliable and accurate analytical methods are necessary. The aim of this work is designing the highly selective sensor to determine the dicloran in biological and environmental samples. Multi-walls carbon nanotubes and a molecularly imprinted polymer (MIP) were used as modifiers in the sensor composition. A dicloran MIP and a nonimprinted polymer (NIP) were synthesized and applied in the carbon paste electrode. After the optimization of electrode composition, it was used to determine the concentration of analyte. Parameters affecting the sensor response were optimized, such as sample pH, electrolyte concentration and its pH, and the instrumental parameters of square wave voltammetry. The MIP-CP electrode showed very high recognition ability in comparison with NIP-CP. The obtained linear range was 1 × 10^?6 to 1 × 10^?9 mol L^?1. The detection limit was 4.8 × 10^?10 mol L^?1. This sensor was used to determine the dicloran in real samples (human urine, tap and river water samples) without special sample preparation before analysis. All important parameters were optimized, improving the sensor response considerably.     

Fabrication of poly(4-aminobenzoic acid/<Emphasis Type="Italic">o</Emphasis>-toluidine) modified carbon paste electrode and its electrocatalytic property to the oxidation of nitrite

The poly(4-aminobenzoic acid/o-toluidine) (4-AB/OT) modified carbon paste electrode (CPE) was fabricated by consecutive cyclic voltammetry. The poly(4-AB/OT) CPE shows catalytic activity for the oxidation of nitrite in 0.1 M phosphate buffer solution (pH 7). Due to the electrostatic interaction between the negatively-charged nitrite ions and the positively-charged poly(4-AB/OT) film, the operating potential for nitrite oxidation was shifted about 240 mV to negative side, compared to bare CPE. The catalytic peak current was found to be linear with the nitrite concentration in the range of 6–600 μM, with a correlation coefficient of 0.981, using amperometry. The sensitivity and limit of detection for the poly(4-AB/OT) CPE are about 187.4 μA/mM and 3.5 μM, respectively. The possible interferences from several common ions were tested. The developed sensor was also successfully applied to the determination of nitrite concentration in a mineral water sample.