Rapid and sensitive determination of biphenyl and biphenyl oxide in water samples using dispersive liquid–liquid microextraction followed by gas chromatography

A rapid and sensitive method has been developed for the determination of biphenyl and biphenyl oxide in water samples using dispersive liquid–liquid microextraction followed by gas chromatography. This method involves the use of an appropriate mixture of extraction solvent (8.0?µL tetrachloroethylene) and disperser solvent (1.0?mL acetonitrile) for the formation of cloudy solution in 5.0?mL aqueous sample containing biphenyl and biphenyl oxide. After extraction, phase separation was performed by centrifugation and biphenyl and biphenyl oxide in sedimented phase (5.0?±?0.3?µL) were determined by gas chromatography-flame ionisation (GC-FID) system. Type of extraction and disperser solvents and their volumes, salt effect on the extraction recovery of biphenyl and biphenyl oxide from aqueous solution have been investigated. Under the optimum conditions and without salt addition, the enrichment factors for biphenyl and biphenyl oxide were 819 and 785, while the extraction recovery were 81.9% and 78.5%, respectively. The linear range was (0.125–100?µg L^?1) and limit of detection was (0.015?µg?L^?1) for both analytes. The relative standard deviation (RSD, n?=?4) for 5.0?µg?L^?1 of analytes were 8.4% and 6.7% for biphenyl and biphenyl oxide, respectively. The relative recoveries of biphenyl and biphenyl oxide from sea, river water and refined water (Paksan company) samples at spiking level of 5.0?µg?L^?1 were between 85.0% and 100 %.     

Continuous contact force models for impact analysis in multibody systems

One method for predicting the impact response of a multibody system is based on the assumption that the impacting bodies undergo local deformations and the contact forces are continuous. In a continuous analysis, the integration of the system equations of motion is carried out during the period of contact; therefore, a model for evaluating the contact forces is required. In this paper, two such contact force models are presented, both Hertzian in nature and based upon the direct-central impact of two solid particles.At low impact velocities, the energy dissipation during impact can be represented by material damping. A model is constructed based on the general trend of the Hertz contact law in conjuction with a hysteresis damping function. The unknown parameters are determined in terms of a given coefficient of restitution and the impact velocity. When local plasticity effects are the dominant factor accounting for the dissipation of energy at high impact velocities, a Hertzian contact force model with permanent indentation is constructed. Utilizing energy and momentum considerations, the unknown parameters in the model are again evaluated. The two particle models are generalized to an impact analysis between two bodies of a multibody system.     

Antioxidant capacity and phenolic composition of leaves from 10 Bene (Pistacia atlantica subsp. kurdica) genotypes

Leaves of 10 Bene genotypes were collected from six provinces (West Azerbaijan, Kurdistan, Kermanshah, Ilam, Hamedan and Lorestan) in Iran. This study was carried out to better characterise the total phenolic and flavonoid contents, antioxidant capacity and phenolic composition, as well as to evaluate the correlation between content of phenolic compounds and antioxidant activity in 10 genotypes of Bene. The antioxidant activity of leaf extracts was measured using different assays: ferric reducing antioxidant power, nitric oxide radical scavenging and 2,2-diphenyl-1-picrylhydrazyl. The results indicated that the antioxidant capacity can be related to total phenolic and flavonoid content, so that among all the genotypes studied here, the highest and the lowest phenolic content and antioxidant activity were observed in B2 and B10 genotypes, respectively. Analysing the phenolic composition using high performance liquid chromatography, caffeic acid, vanillic acid, ferulic acid and sinapic acid were found in all investigated genotypes.     

Synthesis of 3‐substituted indoles promoted by pulverization‐activation method catalyzed by Bi(NO3)3·5H2O

A new, facile, efficient, “green” and chemoselective procedure for the synthesis of indole derivatives has been developed with pulverization‐activation method catalyzed by Bi(NO₃)₃·5H₂O (PAMC‐ Bi(NO₃)₃·5H₂O) through grinding of indoles with aldehydes or Michael acceptors in the presence of catalytic amounts of Bi(NO₃)₃·5H₂O under solvent‐free conditions.     

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.     

Biosynthesis and Chemical Characterization of Silver Nanoparticles Using Satureja Rechingeri Jamzad and Their Apoptotic Effects on AGS Gastric Cancer Cells

Journal of Cluster Science - Since green synthesis of silver nanoparticles (AgNPs) is a simple, safe, cost-effective and eco-friendly method, AgNPs appear to be promising anti-cancer agents in the...     

Differential optical absorption spectroscopy-based refractive index sensor for cancer cell detection

Optical Review - A novel spectroscopic optical sensor is presented for cancerous cell detection in various parts of the human body (i.e., cervix, adrenal gland, breast, skin, and blood). An...     

l-Proline: an efficient catalyst for the synthesis of new spirooxindoles

Abstract  

l-Proline was found to be a versatile organocatalyst for the synthesis of new spirooxindole derivatives in good yields under mild reaction conditions using 1-propanol as a solvent.