Ultrasound-Assisted Emulsification-Microextraction/Ion Mobility Spectrometry Combination: Application for Analysis of Organophosphorus Pesticide Residues in Rice Samples

The present paper describes the validation of ultrasound-assisted emulsification-microextraction method followed by ion mobility spectrometry (IMS) detection for simultaneous determination of two organophosphorus pesticides, diazinon and chlorpyrifos. Ultrasound radiation was applied for accelerating the emulsification of microliter organic solvent in aqueous solutions and enhancing the microextraction efficiency. This preconcentration step combined with IMS detection provided a precise and accurate method for determination of trace amounts of diazinon and chlorpyrifos pesticides. The effect of parameters influencing the extraction efficiency such as sonication time, type of extraction solvent, extraction solvent volume, and salt concentration were investigated and discussed. The enrichment factors found, under optimum conditions, were 230 and 300 for diazinon and chlorpyrifos, respectively, with corresponding LOD of 2.1 and 3.2 μg L^?1. The presented method can be applied for the determination of diazinon and chlorpyrifos in the range 6.0–700 and 8.9–750 μg L^?1, respectively, with correlation coefficients (R ²)?>?0.99. The applicability of the proposed method was evaluated by determination of the residues of the investigated pesticides in rice paddy water gathered from four stations during 60 days after spraying (June 2014), and in storage rice samples in Mazandaran province, Iran.     

A comprehensive modeling framework for collaborative networked organizations

Collaborative networked organizations (CNOs) are complex entities whose proper understanding, design, implementation, and management require the integration of different modeling perspectives. A large number of modeling tools and theories that have been developed in other disciplines have a potential applicability in this domain. Therefore, an identification of the most promising approaches is made and mapped into four dimensions of an endogenous perspective of collaborative networked organizations: structural, componential, functional, and behavioral. But a comprehensive modeling of such complex dynamic systems requires also an exogenous perspective, the life cycle dimension, and a stratification of models according to the modeling purpose. Thus a comprehensive modeling framework is therefore proposed as a first step towards the elaboration of a reference model for collaborative networks.     

Analysis of the Microstructure of Thermal Spray Coatings: A Modeling Approach

Microstructure of coatings produced by thermal spray coating process depends on many parameters, including particle impact conditions, powder materials, and substrate conditions. Because of the large number of parameters affecting microstructure, developing a computational tool that can predict the microstructure of thermal spray coatings as a function of these parameters can be of great interest as it will save time and resources when developing new coatings. In this article, we examine the validity and the accuracy of such a computational tool. We present the result of a three-dimensional model of coating formation. The model is based on the Monte Carlo method with particle impact conditions, materials properties of powder, and substrate as input. The output of the model includes coating porosity, surface roughness, and coating thickness. In order to validate the model, coatings under specific conditions were deposited and the predicted results were compared to the actual deposits. The impact conditions for these cases were measured by DPV-2000 and the raw data were used as input to the computer program. The comparison between the actual deposits and the simulated ones shows good agreement. The results demonstrate the viability and usefulness of this modeling tool in developing new coatings and understanding their microstructure.     

Synthesis and characterization of Pb<Subscript>2</Subscript>SiO<Subscript>4</Subscript> nanostructure: study of photo-catalytic behavior of reactive Red198 and reactive Orange16 dyes as pollutants

Pure Pb₂SiO₄ nanostructures were fabricated using amines as alkaline agents by sol–gel method and characterized via X-ray powder diffraction (XRD), Fourier-transformed infrared spectroscopy (FT-IR), Scanning electron microscopy (SEM), and Energy-dispersive X-ray spectroscopy (EDS). The average crystallite size of the products in presence and absence of the alkaline agent in the reaction was calculated about 18 and 34 nm by XRD technique, respectively. The type of alkaline agent was evaluated to achieve the optimized nanostructure. The results showed that the ethylenediamine as an alkaline agent has a better performance than the other alkaline agents (ammonia, triethylenetetramine, and tetraethylenepentamine). Optical property of optimized nanostructure was studied by diffuse reflectance spectroscopy (DRS) and its band gap was estimated to about 3.3 eV. It is the first time that photo-catalytic behavior of Pb₂SiO₄ nanostructure was investigated. The photo-catalytic performance of optimized Pb₂SiO₄ nanostructure was evaluated in the presence of various concentrations of Reactive Red198 and Reactive Orange16 dyes. The degradation percentage of dyes in various concentrations (5, 7, and 9 ppm) was obtained for Reactive Red198 and Reactive Orange16 about 100, 57, and 52% and also 100, 52, and 42% after 75 min ultraviolet irradiation, respectively. At 5 ppm concentration, Reactive Orange16 pollutant destruction was faster than Reactive Red198.     

Magnetic doping effects on the superconductivity of Y1-xMxBa2Cu3O7-δ (M = Fe,Co, Ni)

The discovery of superconductivity in copper oxide compounds has attracted considerable attention over the past three decades. The high transition temperature (T_c) in these compounds, exhibiting proximity to an antiferromagnetic order in their phase diagrams, remains one of the main areas of research. It is believed that magnetic fluctuations provide substance for the exotic superconductivity observed in these compounds. The present study attempts to introduce Fe, Co and Ni magnetic impurities into the superconducting cuprate YBa₂Cu₃O_7-δ with the aim of exploring the T_c behavior. The solid-state synthesis method is exploited to prepare fully oxygenated Y_1-xM_xBa₂Cu₃O_7-δ (Y_1-xM_x-123) (M = Co, Fe, Ni) samples with low levels of doping (0.00000 ≤ x ≤ 0.03000). Systematic measurements are then employed to assess the synthesized samples using AC magnetic susceptibility, electrical resistivity and X-ray diffraction (XRD). The measurements revealed an increase in T_c as a result of magnetic substitution for Y. However, the study of non-magnetic dopings on the fully oxygenated Y_1-xM'_xBa₂Cu₃O_7-δ (Y_1-xM'_x-123) (M' = Ca, Sr) samples showed a decrease in T_c. Quantitative XRD analysis further suggested that the internal pressure could have minor effects on the increase in T_c. The normal state resistivity vs temperature showed a linear profile, confirming that the samples are at an optimal doping of the carrier concentration.     

Advantages of asymmetrical over symmetrical cells for detection of under deposit CO2 corrosion using electrochemical noise

Electrochemical noise (EN) measurements were done on symmetrical and asymmetrical cells after immersion in 3.5% NaCl solutions saturated with CO₂ and containing different concentrations of sodium bicarbonate to get a better interpretation of the under‐deposit corrosion of mild steel. The symmetrical cell was constructed from two sand‐deposited electrodes and the asymmetrical cell was prepared from one sand‐deposited electrode and one bare electrode. The combination of the standard deviation of partial signal (SDPS) plots arising from wavelet analysis and recurrence plots for analyzing the EN signals obtained from symmetrical and asymmetrical cells confirmed the higher detective ability of the asymmetrical cells in comparison with the symmetrical cells for measuring the under‐deposit corrosion of mild steel. Both the SDPS and recurrence plots arising from symmetrical cells showed no significant change in the corrosion severity of the steel alloy with adding sodium bicarbonate. In contrast, the SDPS and recurrence plots of the asymmetrical cells proved that the corrosion severity decreased initially with adding the bicarbonate and thereafter remained constant with increasing the bicarbonate concentration. The optical microscopy images of the sand‐covered electrode surface confirmed the latter result.     

A new method of Bi-MOF nanostructures production using UAIM procedure for efficient electrocatalytic oxidation of aminophenol: a controllable systematic study

Journal of Applied Electrochemistry - Inverse micelle (IM) and ultrasound-assisted inverse micelle (UAIM) techniques were used to fabricate new Bi-MOF nanostructures. The results showed that the...     

Advancing the Water Footprint into an Instrument to Support Achieving the SDGs – Recommendations from the “Water as a Global Resources” Research Initiative (GRoW)

Water Resources Management - The water footprint has developed into a widely-used concept to examine water use&nbsp;and resulting local impacts caused during agricultural and industrial...