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Nonlinear heterogeneous reactions are important for simulating dissolution as they involve reactant adsorption, reaction, and product desorption, leading to nonlinear behavior. This study proposes a new curved reaction boundary condition in general form in the lattice Boltzmann framework. This method calculates the unknown distribution functions and the interface concentration using extrapolated distribution functions on actual interface position. Various analytical benchmarks were used to compare this method's accuracy with two available schemes, including Kashani et al. and Huber et al. methods. According to the results, in the simulation of reactant transport on straight and curved surfaces with and without dissolution, errors obtained by the proposed method did not exceed 1.7% in different conditions, while errors of the two other methods were up to 50%. The convergence rate of different methods was determined, and based on the results, the convergence rate of the proposed method was second-order, while the corresponding values for the two other methods were only first-order. The results of different root-finding methods in the proposed method including Bisection, Newton-Raphson, and linear approximation were compared to determine the interface concentration. The results showed that Bisection errors did not exceed 1%. At the same time, using Newton-Raphson and linear approximation led to errors of 12.9% and 25.3%, respectively. The effect of reaction orders on an obstacle dissolved under reactive flows in a channel was investigated. According to the results, in each Damköhler number, increasing the reaction order decreased the dissolution rate; however, increasing the Damköhler number significantly restricted the effect of orders. [ABSTRACT FROM AUTHOR]

Covid-19 disease caused by the deadly SARS-CoV-2 virus is a serious and threatening global health issue declared by the WHO as an epidemic. Researchers are studying the design and discovery of drugs to inhibit the SARS-CoV-2 virus due to its high mortality rate. The main Covid-19 virus protease (Mpro) and human transmembrane protease, serine 2 (TMPRSS2) are attractive targets for the study of antiviral drugs against SARS-2 coronavirus. Increasing consumption of herbal medicines in the community and a serious approach to these drugs have increased the demand for effective herbal substances. Alkaloids are one of the most important active ingredients in medicinal plants that have wide applications in the pharmaceutical industry. In this study, seven alkaloid ligands with Quercetin nucleus for the inhibition of Mpro and TMPRSS2 were studied using computational drug design including molecular docking and molecular dynamics simulation (MD). Auto Dock software was used to evaluate molecular binding energy. Three ligands with the most negative docking score were selected to be entered into the MD simulation procedure. To evaluate the protein conformational changes induced by tested ligands and calculate the binding energy between the ligands and target proteins, GROMACS software based on AMBER03 force field was used. The MD results showed that Phyllospadine and Dracocephin-A form stable complexes with Mpro and TMPRSS2. Prolinalin-A indicated an acceptable inhibitory effect on Mpro, whereas it resulted in some structural instability of TMPRSS2. The total binding energies between three ligands, Prolinalin-A, Phyllospadine and Dracocephin-A and two proteins MPro and TMRPSS2 are (-111.235 ± 15.877, - 75.422 ± 11.140), (-107.033 ± 9.072, -84.939 ± 10.155) and (-102.941 ± 9.477, - 92.451 ± 10.539), respectively. Since the binding energies are at a minimum, this indicates confirmation of the proper binding of the ligands to the proteins. Regardless of some Prolinalin-A-induced TMPRSS2 conformational changes, it may properly bind to TMPRSS2 binding site due to its acceptable binding energy. Therefore, these three ligands can be promising candidates for the development of drugs to treat infections caused by the SARS-CoV-2 virus. [ABSTRACT FROM AUTHOR]

A magnetic dispersive solid phase extraction method combined with solidification of floating organic droplet-based dispersive liquid–liquid microextraction has been validated for the extraction of polycyclic aromatic hydrocarbons from honey samples. For this purpose, a carbonised cellulose–ferromagnetic nanocomposite was used as a sorbent through the magnetic dispersive solid phase extraction. For preparation of the sorbent, first, carbonised cellulose nanoparticles were created by treating cellulose filter paper with concentrated solution of sulfuric acid. Then, the prepared nanoparticles were loaded onto Fe3O4 nanoparticles through coprecipitation. In the extraction process, first, a few mg of the sorbent was added to the diluted honey solution and dispersed in it using vortex agitation. The particles were then separated and the adsorbed analytes were eluted with an organic solvent. The eluent was taken and after mixing with a water–immiscible extraction solvent was used in the following solidification of floating organic droplet-based dispersive liquid–liquid microextraction procedure. By performing the extraction process under the obtained optimum conditions, low limits of detection (0.08–0.17 ng g−1) and quantification (0.27–0.57 ng g−1), satisfactory precision (relative standard deviations ≤ 5.0%), and wide linear range (0.57–500 ng g−1) with great coefficients of determination (r2≥ 0.9986) were obtained. [ABSTRACT FROM AUTHOR]

Extensive studies on the thermophysical behavior of nanofluids have been conducted so far; however, the mechanisms behind the change in the thermophysical properties of nanofluids remain unclear. In this study, the influences of Brownian motions of nanoparticles, induced micro-convection, interfacial nanolayer and ballistic phonon transport mechanisms on improving the thermophysical and rheological properties of Cu–water nanofluids were investigated using equilibrium and non-equilibrium molecular dynamics simulations. For this purpose, the nanoparticle was dispersed in the base fluid in three different cases: free, fixed and fixed-rigid. Then, the fundamental and nanostructural properties of nanofluids such as fluid velocity contours, number (mass) density, potential energy, temperature gradient inside and around the nanoparticle and random motions of the nanoparticle were analyzed to explore the best mechanism for thermophysical and rheological properties changes in nanofluids. The SPC/E model was used to calculate the interactions between water molecules, while the embedded-atom-method potential was applied for Cu–Cu interatomic interactions. The nanofluids were created by dispersing spherical Cu nanoparticles with a diameter of 2.6 nm in liquid water at 6.5 vol%. The results showed that the shear viscosity and thermal conductivity of nanofluid increased by 38.47% and 6.5%, respectively, compared to the base fluid, while the self-diffusion coefficient decreased by 18.24%. It was also found that the Brownian motion of nanoparticles, ballistic phonon transport and micro-convection mechanisms have no significant effect on the thermophysical properties of nanofluid. According to the results, it was concluded that the formation of the interfacial nanolayer around nanoparticles is the key most important factor in improving the thermophysical properties of nanofluids and the properties of this layer can have a considerable effect on the nanofluid properties. It was explained that the interatomic interactions between the nanoparticle atoms and the base fluid play a key role in forming the interfacial nanolayer structure. [ABSTRACT FROM AUTHOR]

In this study, a hyphenated sample pretreatment method based on coupling dispersive solid phase extraction and dispersive liquid–liquid microextraction has been employed for the extraction of some pesticides (chlorpyrifos, clodinafop–propargyl, diniconazole, fenpropathrin, oxadiazon, penconazole and tebuconazole) from fruit juice samples before their quantification by gas chromatography–flame ionisation detection. For this purpose, first a nitrogen–doped amorphous carbon nanocomposite is prepared from L–cysteine and sorbitol using an economically affordable and fast procedure and then it is used as an efficient sorbent for the analytes extraction from the samples in dispersive solid phase extraction step. After that acetonitrile is used to desorb the adsorbed analytes from the sorbent. In the next step, to more concentrate the analytes, the acetonitrile phase is taken and mixed with 1,2–dibromoethane at µL–level. The mixture is applied in the following dispersive liquid–liquid microextraction. Validation data indicated that the developed method provided high enrichment factors (719–867) and extraction recoveries (72–87%), low limits of detection (0.49–0.98 μg L–1) and quantification (1.6–3.3 μg L–1), and an acceptable repeatability (relative standard deviations ≤ 5.4 and 6.4% for intra – and inter–day precisions, respectively). [ABSTRACT FROM AUTHOR]

The method of volume of fluid is a popular method often used to calculate normal vectors in simulating two-phase flows. This study proposes a new method based on scalar diffusion phenomenon using smoothed profile combined with lattice Boltzmann method. The method is spatially and time-wisely local, which facilitates its parallel implementation. Accuracy and computational time of the proposed method on straight and curved surfaces in single- and multi-obstacle media were compared with four standard methods: Youngs, efficient least-square volume of fluid interface reconstruction algorithm (ELVIRA), Swartz, and coupled volume of fluid and level set (VOSET). In addition, the problems of heterogeneous dissolution of porous media under reaction-controlled and natural conditions were simulated. The results showed that in terms of the calculated angles, the proposed method is 0.4°–1.52° more accurate than the common Youngs method. Additionally, its computational time was about 36% less than that of the Youngs method. Compared with ELVIRA, Swartz, and VOSET, despite their marginal higher accuracy, their computational times were 346%–772% higher. Furthermore, it was shown that the accuracy of ELVIRA and Swartz methods in multi-obstacle media decreases significantly with decrease in gap between the neighboring obstacles. However, for the proposed method, the effect of gap was considerably less significant. [ABSTRACT FROM AUTHOR]

In present study, a new sample pretreatment method based on the combination of stirring-assisted ferrofluid-based liquid phase microextraction and dispersive liquid–liquid microextraction has been developed for the extraction of some pesticides (diazinon, deltamethrin, fenpropathrin, phosalone, prometryn, simazine, and terbutryn) from herbal distillate samples. In this method, a few microlitre of a synthesised ferrofluid as an extraction solvent is added into the sample solution containing the analytes and the mixture is stirred at a high rate to increase the contact area between the ferrofluid and sample solution. Then the stirring procedure is stopped and the ferrofluid droplets containing the analytes are collected on the surface of stir bar. In the next step, the stir bar is washed with acetonitrile. In the following, the obtained mixture of acetonitrile and ferrofluid is rapidly injected into deionised water. The ferrofluid droplets are settled down at the bottom of a conical test tube and after back-extraction of the analytes into n-hexane, an aliquot of the extractant phase is injected into gas chromatography–mass spectrometry. Under optimum conditions, the introduced method offered high enrichment factors (1643−1884) and extraction recoveries (82–94%), low limits of detection (3.1–7.3 ng L–1) and quantification (10.3–24.3 ng L–1), and an acceptable repeatability (relative standard deviation ≤ 7.9%). [ABSTRACT FROM AUTHOR]

In this study, a solid phase extraction method followed by dispersive liquid–liquid microextraction has been developed for the extraction and preconcentration of five triazole pesticides (penconazole, hexaconazole, diniconazole, tebuconazole, and triticonazole) in grape juice. Initially, a high volume of the sample solution is passed through the solid phase extraction cartridge and then the absorbed analytes are eluted by an appropriate solvent (methanol) which acts as a dispersive solvent in the following microextraction procedure. Then, the eluate is mixed with 1,1,2,2,–tetrachloroethane as an extraction solvent and the mixture is rapidly injected into sodium chloride solution. After centrifugation, an aliquat of the obtained sedimented phase is injected into gas chromatography–flame ionisation detection. Some effective parameters on performance of the method such as washing and elution solvents type and volume, extraction solvent, etc were investigated. Under optimum conditions (sample solution volume, 100 mL; flow rate, 10 mL min–1; elution solvent (volume), methanol (1.0 mL); extraction solvent (volume), 1,1,2,2–tetrachlorothene (25 µL); aqueous phase in DLLME, sodium chloride solution (30%, w/v); and centrifugation time (speed), 5 min (3000 rpm)), the method showed high enrichment factors (4101–9566) and low limits of detection (0.053–0.890 ng mL–1) and quantification (0.178–2.96 ng mL–1). Finally, ten grape juices were successfully analysed by this method and hexaconazole was detected in some of them in the concentration range of 19–29 ng mL–1. [ABSTRACT FROM AUTHOR]

Background: Endometriosis is a multifaceted gynecological disorder defined as a benign estrogen-dependent chronic inflammatory process in which endometrial glands and stroma-like tissues are located outside the uterine cavity. It affects around 2-10% of all women during their reproductive years. Objective: This study aimed to evaluate the traffic of mesenchymal stem cells and inflammatory factors toward the lesions. Materials and Methods: Ten samples of normal endometrium and eutopic endometrium were studied as a control group and 10 ectopic samples were considered as a case group. Hematoxylin and eosin staining was used to evaluate stromal cells and inflammatory cells. Immunohistochemical staining was performed to show the presence of proliferating cell nuclear antigen in the lesions. The cells were digested and cultured in the laboratory to study cell proliferation. The number of cells and vessels were counted with Image J software, and data analysis was performed with Prism software. Results: Data analysis showed that the number of stromal cells and vessels in ectopic tissue were significantly higher than the control group (p <0.001). Also, the number of inflammatory cells, including neutrophils, monocytes, lymphocytes, and macrophages, in the ectopic group was much higher than in the control group (p <0.005). Conclusion: By expanding the number of blood vessels, blood flow increases, and cell migration to tissues is facilitated. The accumulation of inflammatory cells, especially macrophages, stimulates the growth of stem cells and helps implant cells by creating an inflammatory process. [ABSTRACT FROM AUTHOR]

BACKGROUND A combination of magnetic solid‐phase extraction using an efficient and cheap magnetic sorbent obtained from sand and dispersive liquid–liquid microextraction has been developed for the extraction of nine multiclass pesticides (clodinafop‐propargyl, haloxyfop‐R‐methyl, fenoxaprop‐P‐ethyl, oxadiazon, penconazole, diniconazole, chlorpyrifos, fenazaquin, and fenpropathrin) from commercial fruit juices (sour cherry, pomegranate, grape, watermelon, orange, apricot, and peach juices). The enriched pesticides were determined by gas chromatography–flame ionization detector and gas chromatography–mass spectrometry. The sorbent was natural iron oxide entrapped in silica along with some impurities. In this method, to extract the analytes from the samples, an appropriate amount of the magnetic sorbent (at mg level) is added. Then the sorbent particles are isolated from the solution using an external magnetic field and the adsorbed analytes are desorbed from the sorbent by acetone. In the following, a dispersive liquid–liquid microextraction procedure is carried out to concentrate the analytes more and to reach low limits of detection. RESULTS: Under optimized extraction conditions, the method revealed satisfactory repeatability (relative standard deviation ≤8% for intra‐day and inter‐day precision), reasonable extraction recovery (43.3–55.9%), high enrichment factors (433–559), and low limits of detection (0.45–0.89 μg L−1). CONCLUSION: The method was applied in the analysis of pesticides in various fruit juices. Chlorpyrifos was found in peach juice at a concentration of 27 ± 2 μg L−1 (n = 3) using a gas chromatography–flame ionization detector. To verify the results, the peach juice was also injected into gas chromatography–mass spectrometry after applying the proposed extraction method. © 2022 Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

• Effects of micro grains on solute transport in porous media were investigated. • Lattice Boltzmann method was used for simulation of heterogeneous dissolution in porous media. • Patterns of dissolution in media with single and dual porosities were compared. • Two major regimes of face and wormhole dissolutions were studied. Understanding the influence of porous media structure, particularly dual porosity, on solvent transport and pore geometry evolution during chemical reactions is a complex and critical area of study. This research leverages the lattice Boltzmann method to investigate how the presence of aggregates in a medium affects solvent transport and pore space development, focusing on distinct dissolution regimes: face and wormhole dissolution. The study addresses the challenge of managing variable pore sizes in dual porosity media by developing specialized GPU algorithms, which efficiently handle fine grids and complex pore spaces. The findings reveal that dual porosity significantly enhances dissolution rates in both the face and wormhole dissolution regimes. Intriguingly, while the pattern of face dissolution remains largely unchanged, dual porosity markedly alters the pattern of wormhole dissolution. In dual-porosity media, the wormholes tend to be narrower and more elongated compared to the wider wormholes observed in single-porosity media. This variation is attributed to the reaction area dynamics, where the reduced reactive surface area along the main wormhole path in dual-porosity media results in less solvent engagement in the reaction processes. Moreover, the research provides insights into the microscale interactions in porous media, emphasizing how variations in microscale porosity can have substantial impacts on the overall dissolution dynamics. The study results are not only significant for understanding the fundamental aspects of chemical dissolution in porous media but also have practical implications in fields such as geo-energy and groundwater remediation. These findings help optimizing reaction processes in complex and heterogeneous porous systems, highlighting the need for detailed consideration of microstructural characteristics in modeling and industrial applications. [ABSTRACT FROM AUTHOR]

A temperature‐induced counter‐current homogenous liquid‐liquid extraction procedure performed in a burette has been proposed for the isolation of aflatoxins B1, B2, G1, and G2 from various fruit chip samples. In this method, a homogenous solution of deionized water and cyclohexylamine is added to the solid sample and the resulted mixture is vortexed. In the following, the liquid phase is taken and passed through the burette filled with a mixture of calcium oxide (as a phase separation agent) and sand (to avoid clumping the calcium oxide). By doing so, the temperature of the solution is increased by hydration of calcium oxide and consequently, the homogenous state is broken and the aflatoxins are migrated into the resulted tiny droplets of cyclohexylamine. This phase is collected on the top of the solution owing to its low density with respect to an aqueous solution. Numerous parameters which can affect the efficiency of the suggested approach were evaluated and under the best situations, great repeatability, low limits of determination and quantification, and high extraction recoveries were acquired. In the end, the suggested approach was employed for the quantification of the selected aflatoxins in various fruit chips samples marketed in Tabriz City, Iran. [ABSTRACT FROM AUTHOR]

A heat pipe, which contains evaporator, adiabatic, and condenser, is a simple device with proper heat transfer rate and a little heat loss, without any moving parts. In this study, the effects of length of the three mentioned sections of heat pipe were investigated through introducing the ratio of adiabatic length to the condenser length or evaporator length as aspect ratio (AR), filling ratio of working fluid, and heat load on the thermal performance of a thermosyphon heat pipe by combining computational fluid dynamics (CFD) and design of experiment (DOE). Optimum conditions were obtained using DOE. Prior to determining the optimum conditions, the heat pipe was simulated using volume of fluid model through solving the governing equations of mass, momentum, and energy for evaporation and condensation phenomena by finite volume method. The results were confirmed by comparing the 2D CFD simulation results with the experimental data. The purpose of this research was to find the optimal lengths of different parts. The results showed that the averaged optimum values for the above mentioned parameters (AR, heat load, and filling ratio) were 0.8325, 246 W, and 85%, respectively. In total, thermal performance of the heat pipe was improved for lower adiabatic zone length and higher values of heat load and filling ratio. [ABSTRACT FROM AUTHOR]

In this paper, we propose three new compressive sensing-based algorithms for channel estimation in millimeter wave hybrid MIMO systems over doubly (time and frequency) selective channels. Utilizing the basis expansion model (BEM) for effectively representing doubly selective channels, we first propose a BEM-based block orthogonal matching pursuit (BBOMP) algorithm, which can work with any training sequence structure. Next, we present the second algorithm to reduce the complexity of the BBOMP method by employing a special training sequence which results in a computationally efficient block sparse sensing matrix. Finally, in order to further decrease the computational complexity, we propose the third algorithm, where the channel estimation is split into two separate steps of tap detection and gain estimation. The proposed algorithms exploit the entire available training sequence to estimate all channel parameters, and can capture channel variations across the entire training frames without requiring a feedback channel. The Cramer-Rao lower bound and the computational complexity of the proposed algorithms are also addressed. Intensive computer simulations are conducted to evaluate the accuracy of the proposed approaches, showing that they can significantly improve the mean squared error performance compared with the state-of-the-art approaches. [ABSTRACT FROM AUTHOR]

A green and centrifuge-less microwave-accelerated air assisted liquid–liquid microextraction method based on solidification of deep eutectic solvent droplet has been developed for the extraction of some endocrine-disrupting compounds in injection solutions prior to their determination by gas chromatography–mass spectrometry. Under optimum conditions, limits of detection and quantification were obtained in the ranges of 14–33 and 47–110 ng L–1, respectively. Extraction recovery (ER) and enrichment factor (EF) of the selected analytes ranged from 79% to 94% and 395–470, respectively. The relative standard deviations were ≤7% for intra- (n = 6) and inter-day (n = 4) precisions at a concentration of 250 ng L–1 of each analyte. Abbreviations: AALLME: Air-assisted liquid–liquid microextraction; DEP: Diethyl phthalate; DBP: Dibutyl phthalate; BPA: Bisphenol A; DEHP: Di-(2-ethylhexyl) phthalate; DIBP: Di-iso-butyl phthalate; EF: Enrichment factor; ER: Extraction recovery; GC: Gas chromatography; LOD: Limit of detection; LOQ: Limit of quantification; LR: Linear range; MS: Mass spectrometry; RSD: Relative standard deviation; PE: Phthalate ester [ABSTRACT FROM AUTHOR]

[Display omitted] • A magnetic bio–metal–organic framework was synthesized and employed as an efficient sorbent. • 16 different PAHs were efficiently extracted using MDSPE-DLLME procedure. • The extracted PAHs were determined using GC–MS. • Ease of operation, greenness, and simplicity are the main advantages of the method. This work describes the development of a magnetic dispersive solid phase extraction method based on using bio–metal–organic framework (prepared from vitamin B 3 and cobalt salt in water medium) as an efficient sorbent for the extraction of polycyclic aromatic hydrocarbons from milk samples. Briefly, the synthesized sorbent at mg–level is added to the supernatant phase after precipitating the proteins of milk sample and the mixture is vortexed. In the presence of magnetic field, the supernatant is removed and the sorbent particles containing the adsorbed analytes are eluted by using an appropriate organic solvent. The eluted analytes are more enriched using a magnetic ionic liquid–based dispersive liquid–liquid microextraction. After back–extraction of the analytes into n–hexane, the analytes are determined using gas chromatography–mass spectrometry. The experimental variables influencing the suggested method efficiency such as zinc sulfate solution concentration and volume, and vortexing time in proteins precipitating step, sorbent amount, adsorption time, ionic strength, elution solvent type and volume, desorption time, extraction solvent type and volume, and back–extraction solvent type, volume and time in extraction procedure were optimized by one parameter at a time strategy. Under the optimum conditions, low limits of detection (38–78 ng L−1) and quantification (130–260 ng L−1), high extraction recoveries (58–82%) and enrichment factors (145–205), and good precision (relative standard deviations ≤6.1%) were obtained. Finally, the developed method was effectively employed for quantification of polycyclic aromatic hydrocarbons in pasteurized milk samples. [ABSTRACT FROM AUTHOR]

Herein, an efficient and simple sample pretreatment method based on a combination of low temperature-induced homogeneous liquid–liquid extraction and ternary deep eutectic solvent-based dispersive liquid–liquid microextraction has been proposed for the extraction of multiclass pesticides in cucumber samples before their determination with gas chromatography-flame ionization detection. In this study, acetonitrile is added to a tube containing crushed cucumber sample (scum and juice) and the mixture is agitated manually. Acetonitrile and juice of the sample form a homogeneous solution. Then the mixture is cooled using liquid nitrogen for a few seconds. By this action, the aqueous phase is freezed and the analytes are extracted into liquid acetonitrile phase collected on the freezed aqueous phase. The obtained acetonitrile phase is mixed with the synthesized ternary deep eutectic solvent produced from choline chloride, acetic acid, and 4-chlorophenol (as an extraction solvent) and rapidly injected into deionized water placed into a conical bottom test tube. Consequentially, a cloudy state is formed and the tiny droplets of the extractant containing the extracted analytes are sedimented at the bottom of the tube after centrifugation. A fraction of the sedimented phase is removed with a microsyringe and injected into the separation system for analysis. Under the optimum conditions, enrichment factors and extraction recoveries were in the ranges of 290–405 and 58–81%, respectively. The limits of detection and quantification were in the ranges of 0.42–0.88 and 1.5–2.9 ng g−1, respectively. The method precision, expressed as relative standard deviation, was ≤7.8% for intra- (n = 6) and inter-day (n = 4). The proposed method was successfully applied to the analysis of the selected pesticides in various cucumber samples and chlorpyrifos was determined in three samples at a ng g−1 level. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Copper electrowinning cell was studied under magnetic field and operating parameters. • A continuous process in presence of an industrial Fe3+ ion in electrolyte was used. • Magnetic field decreased current efficiency in presence of Fe3+ ions as rival ions. • Increasing Fe3+ concentration decreased CE and formed FT microstructure. • All factors except Cu2+ concentration had overall positive effect on thickness uniformity. Abstract Current efficiency and quality of deposited copper are important parameters in copper electrowinning industries. The effects of imposing an external magnetic field, Fe3+ and Cu2+ mass concentrations and electrical current density on the current efficiency, the thickness of the cathodic copper sheet and its morphology in copper electrowinning process were studied at different experimental operating conditions in a cuboid cell. A full factorial design of experiment is applied here to relate current efficiency and the standard deviation (STDEV) of the thickness with and without magnetic field, Fe3+ concentration (2.5 and 3.5 g/L), Cu2+ concentration (35 and 40 g/L) and electrical current density (150 and 220 A/m2) with constant acid concentration of 175 g/L at temperature of 40 °C for a synthetic electrolyte. Scanning electron microscope (SEM) is applied in studying the surface morphology of the deposited cathodic copper in all tests. The obtained results indicated that the presence of the magnetic field and increasing Fe3+ concentration could decrease the current efficiency up to 17 and 7%, respectively. While increasing Cu2+ concentration and electrical current density increased the current efficiency. Presence of magnetic field, increasing Fe3+ concentration and electrical current density increased the thickness uniformity of copper sheets. Investigation of SEM surface images revealed variations in these main parameters had different effects on deposited cathodic copper morphology. [ABSTRACT FROM AUTHOR]

Highlights • With irradiation of ultrasonic waves percolation paths of oil increased. • Ultrasonic waves intensify oil layering mechanism due to the peristaltic movements. • For using ultrasonic waves, type of oil and geometry of model should be considered. • Ultrasonic waves caused fluid in throat easier overcoming the capillary forces. Abstract If the current trends of oil recovery from the oil reservoirs continue, the level of oil production will significantly reduce soon. This intense reduction will challenge the current methods for enhanced oil recovery since they will lose their capability and efficiency to meet the required targets. Accordingly, applying new and efficient methods to improve oil recovery are essential. In this study, ultrasound waves were applied to investigate its effect on oil recovery during distilled waterflooding under temperature control. The effect of ultrasound on the oil recovery was studied in a glass micro-model for different model geometries. Experiments were conducted using two types of oil (different in their viscosities) and micro models (different in their geometries). One of the micro models had three types of different geometries and fluid after passing through each geometry enters into the next geometry. Results showed that ultrasonic waves improved oil recovery, oil mobility and eventually oil percolation paths. However, the ultimate recovery of the oil not only depends upon the viscosity of the oil but also the geometry of the micro-model used. The effect of ultrasonic waves was more significant for the oil with lower viscosity. The ability of ultrasonic waves on fluid flow in a porous medium depends on the stratigraphy and geometry of these media. Consequently, if ultrasonic waves are used for EOR/IOR, the type of oil and geometry of porous media should be considered. [ABSTRACT FROM AUTHOR]

Abstract In recent years, liquid phase microextraction (LPME) as a solvent–minimized and microscale implementation of sample pretreatment procedure of liquid–liquid extraction has been introduced and obtained great attention among the researchers due to its simplicity, low cost, rapidity, and efficiency. Developments have led to different approaches of LPME such as headspace mode of liquid phase microextraction (HS mode of LPME) which is used in the cases of volatile and semi–volatile analytes. In HS mode of LPME, the extractant is suspended in the headspace of analytes solution and has no contact with the sample solution which leads to eliminate interferences problem. The present review discusses HS mode of LPME with the focus on its historical developments, principles, configurations, inherent limitations, and pros and cons. Herein, recent analytical applications of the method used in the isolation and trace enrichment prior to analysis of various compounds are reviewed. The future direction of the researches in this field and general trend toward the commercial applications are also considered. Highlights • Historical developments and principles of HS mode of LPME have been reviewed. • Pros and cons of HS mode have been discussed. • Analytical applications and automation have been covered. • Future potential developments have been prospected. [ABSTRACT FROM AUTHOR]

Abstract 5-Nonylsalicylaldoxime (NSAO) is a well-known and strong extractant reagent, which is mainly used in the solvent extraction of copper and other metal ions. In this study, for the first time, the dynamic and thermodynamic properties and structure of 5-Nonylsalicylaldoxime were investigated by molecular dynamics (MD) simulation using the CHARMM force field. The results were validated against the experimental data of 5-Nonylsalicylaldoxime, which was synthesised by these authors. The self-diffusion coefficient was calculated based on both the Green-Kubo and Einstein methods that were in excellent agreement with each other. To understand the structure of NSAO, the FTIR spectroscopy of this reagent was computed by MD simulation and compared with the FTIR spectrum of the synthesised one. There was a good agreement between the calculated and experimental spectra. Moreover, based on the radial distribution function (RDF) and coordination numbers, it was shown that the formation probability of non-complexing isomer (Z-isomer) for NSAO molecules was greater than that of the complexing isomer (E-isomer). Highlights • For the first time, MD and experimental studies were performed for 5-Nonylsalicylaldoxime (NSAO). • Self-diffusion coefficient was obtained from Greek-Kubo and Einstein methods. • There was a good agreement between experimental and simulated FTIR of NSAO. • The formation probability of non-complexing isomer of NSAO is higher than the complexing isomer. [ABSTRACT FROM AUTHOR]

In the present work, a simultaneous derivatization and air–assisted liquid–liquid microextraction method based on the solidification of deep eutectic solvent coupled with gas chromatography–mass spectrometry has been developed for the determination of some aromatic amines in various aqueous samples. In this work, choline chloride and n –butyric acid are mixed at a suitable molar ratio and after heating, a deep eutectic solvent of low density compared to water is formed. The prepared extraction solvent is mixed with ethyl chloroformate as a derivatization agent and injected into an alkaline aqueous solution containing the target analytes adjusted at elevated temperature. The resulting mixture is drawn into a syringe via a needle and pushed out into a test tube several times. As a result, a cloudy solution consisting of the fine droplets of the extraction solvent containing the derivatized aromatic amines is obtained. Then, the solution is placed into an ice bath and the extraction solvent is solidified and collects on the top of the solution after centrifugation. Then the solidified extraction solvent is removed by a spatula and transferred to a microtube and dissolved in 10 μL acetonitrile. A portion of the obtained mixture is injected into the gas chromatography–mass spectrometry. Under optimum conditions, limits of detection and quantification were obtained in the ranges of 1.8–6.0, and 6.0–23 ng L −1 , respectively. The extraction recoveries, enhancement factors, and enrichment factors of the selected aromatic amines ranged from 79–94%, 2498–3422 and 790–940, respectively. The relative standard deviations were ≤5.3% for intra– (n = 6) and inter–day (n = 4) precisions at a concentration of 100 ng L −1 of each analyte. [ABSTRACT FROM AUTHOR]

Highlights • A novel analytical method termed DSPE–DES–AALLME–GC–MS has been developed. • The method was applied for the determination of TCA drugs in biological fluids. • LODs and LOQs were achievable at ng L–1. • Use of green deep eutectic solvent made the method environmentally friendly. • The proposed microextraction method is green, simple and cost-benefit. Abstract A dispersive solid phase extraction coupled with deep eutectic solvent–based air–assisted liquid–liquid microextraction has been developed and applied to the extraction and preconcentration of some tricyclic antidepressant drugs in the human urine and plasma samples prior to their determination by gas chromatography–mass spectrometry. In this method, a sorbent (C 18) is first added into an alkaline aqueous sample and dispersed by vortexing. By this action, the analytes are adsorbed onto the sorbent. Then, the sorbent particles are isolated from the aqueous solution by centrifugation. Afterward, a deep eutectic solvent, prepared from choline chloride and 4–chlorophenol is used to desorb the analytes from the sorbent. Subsequently, the supernatant solution is removed and added into an alkaline deionized water placed into a test tube with a conical bottom. The resulting mixture is rapidly sucked into a glass syringe and then injected into the tube. This procedure is repeated for several times and a cloudy solution consisting of fine droplets of deep eutectic solvent dispersed into the aqueous phase is formed. After centrifuging the obtained cloudy solution, the tiny droplets of the extractant, containing the extracted analytes, settle at the bottom of the tube. Finally, an aliquot of the extractant is taken and injected into the separation system for quantitative analysis. Several significant factors affecting the performance of the proposed method are evaluated and optimized. Under optimum extraction conditions, the method shows low limits of detection in the ranges of 5–10, 8–15 and 32–60 ng L−1 in deionized water, urine, and plasma, respectively. Enrichment factors are observed to be between 325 to 385 in deionized water, 155 to 185 in urine, and 64 to 72 in plasma. Extraction recoveries are in the range of 65–77 (in deionized water), 62–74 (in urine), and 64–72% (in plasma). The relative standard deviations of the proposed method are ≤ 6% for intra– (n = 6) and inter–day (n = 4) precisions at a concentration of 200 ng L–1 of each analyte. Finally, the applicability of the introduced method is investigated by analyzing the selected drugs in different biological fluids. In the proposed method, for the first time, a deep eutectic solvent composed of safe, cheap, and biodegradable compounds was synthesized and used (at μL–level) as an elution and extraction solvent, simultaneously which led to omit the consumption of toxic organic solvents. This represents a significant advantage in the era of green chemistry. In addition, the introduced method is sensitive, simple in operation, rapid, and efficient. [ABSTRACT FROM AUTHOR]

A well-known complication in the oil reservoir during oil production is asphaltene deposition in and around the production wellbore. Deposition of asphaltene around the production wellbore may cause a significant pressure drop and in turn loss of efficiency in the production process. Various mechanical and chemical methods have been employed in order to reduce asphaltene formation or to eliminate the precipitate. A novel technique which presented a great potential for prevention or elimination of asphaltene is spreading out the high energy ultrasound wave within the oil reservoir. In this study, in a glass micro-model, asphaltene precipitation was first simulated in a transparent porous medium and its removal by application of high energy ultrasound wave was then investigated. To simulate asphaltene precipitation, the micro-model was first saturated with oil and then a normal-pentane was injected. This was followed by flooding the porous media with brine while propagating ultrasound waves (30 kHz and 100 W) to eliminate asphaltene precipitation. The experiment setup was equipped with a temperature controller. The results indicate a significant reduction in asphaltene precipitation in the oil reservoir may be achieved by application of ultrasound energy. Asphaltene particle deposition has been solved reversibly in the oil layer of porous medium and with the oil layering mechanism, the rate of oil production has been increased. In some spots, water/oil emulsion has been formed because of the ultrasonic vibration on the wall. Both the crude and synthetic oils were examined. [ABSTRACT FROM AUTHOR]

Hurriclon cyclone is a specially designed preheater cyclone with two outlet connector pipes of cleaned gas in the cement industry. In Kerman cement plant, Iran, the initial structure of this cyclone was changed. This caused a decrease in the cyclone efficiency. In this study, to optimize the changed cyclone performance, one of the twin cyclones in the first-stage of the preheater tower, which had the most significant effect on particle separation from gas was simulated and validated by computational fluid dynamics. Using the design of experiment based on the simulation results, the effects of three dimensions (vortex-finder length, cylinder height, and cone tip diameter) were investigated on cyclone performance. The turbulent gas flow inside the cyclone was modelled using the Reynolds stress model due to the swirling flow inside the cyclones. The discrete phase model was used to calculate the trajectory of particles. It was observed that because of high gas inlet velocity and particle density as well as the geometry of the preheater cyclone, particles larger than the critical diameter continue spinning in the cyclone. The Multi-Gene Genetic Programming (MGGP) was used to obtain two equations for efficiency and pressure drop in order to optimize the preheater cyclone performance. For this purpose, two-objective optimization using the Genetic Algorithm (GA) was performed. The optimization results showed that by using the optimized dimensions for the preheater cyclone, the pressure drop decreases by 2.2% and the efficiency increases by 13.4%. [ABSTRACT FROM AUTHOR]

In this study, for the first time, a magnetic dispersive solid phase extraction method using an easy–accessible, cheap, and efficient magnetic sorbent (toner powder) combined with dispersive liquid–liquid microextraction has been developed for the extraction and preconcentration of some widely used pesticides (diazinon, ametryn, chlorpyrifos, penconazole, oxadiazon, diniconazole, and fenazaquin) from fruit juices prior to their determination by gas chromatography–flame ionization detection. In this method, the magnetic sorbent is mixed with an appropriate dispersive solvent (methanol–water, 80:20, v/v ) and then injected into an aqueous sample containing the analytes. By this action the analytes are rapidly adsorbed on the sorbent by binding to its carbon. The sorbent particles are isolated from the aqueous solution in the presence of an external magnetic field. Then an appropriate organic solvent (acetone) is used to desorb the analytes from the sorbent. Finally, the obtained supernatant is mixed with an extraction solvent and injected into deionized water in order to achieve high enrichment factors and sensitivity. Several significant factors affecting the performance of the introduced method were investigated and optimized. Under the optimum experimental conditions, the extraction recoveries of the proposed method for the selected analytes ranged from 49–75%. The relative standard deviations were ≤7% for intra- (n = 6) and inter-day (n = 4) precisions at a concentration of 10 μg L –1 of each analyte. The limits of detection were in the range of 0.15–0.36 μg L –1 . Finally, the applicability of the proposed method was evaluated by analysis of the selected analytes in some fruit juices. [ABSTRACT FROM AUTHOR]

In this work, an efficient sample pretreatment method has been developed by combining salt induced- homogenous liquid-liquid extraction, dispersive solid phase extraction, and dispersive liquid-liquid microextraction based on the solidification of floating organic droplet for the extraction of some widely used tricyclic antidepressant (TCA) drugs (nortriptyline, amitriptyline, desipramine, clomipramine, and imipramine) in human urine samples before their determination by high performance liquid chromatography-ultraviolet detection. In brief, the target analytes are first isolated from urine samples into acetonitrile (ACN) separated by adding a salt. Then the obtained ACN phase is treated with a mixture of appropriate sorbents to remove interferences. Afterward, the purified ACN is mixed with menthol as an extractant and rapidly injected into alkaline HPLC-grade water as a preconcentration step. Next, the obtained solution is placed in an ice bath and menthol collects on top of the solution after solidification. The solidified drop is then withdrawn and injected into separation system after dissolving in 10 µL ACN. Under the optimum experimental conditions, extraction recoveries and enrichment factors of the selected drugs ranged from 69-84% and 345-420, respectively. The limits of detection and quantification were obtained at the ranges of 0.22-0.31, and 0.71-1.1 µg L-1, respectively. The relative standard deviations of the proposed method were = 6% for intra- (n=6) and inter-day (n=4) precisions at a concentration of 10 µg L-1 (each drug). Finally, the suggested approach was applied to determine of TCA drugs in different patients' urine samples. The method could be applied in further TCAs pharmacokinetic and forensic studies. [ABSTRACT FROM AUTHOR]

Buoyancy induced flow is one type of flow that can occur in relation to a wide range of hydrocarbon reservoir, deep circulation of groundwater and flow around buried radioactive waste. The objective of the present study was to study the transient two-dimensional natural convection in a fractured porous medium. A computational fluid dynamics (CFD) simulation was carried out to study the velocity and temperature distribution between the two bases of a horizontal solid slab containing a fluid-filled fracture that crosses the slab. The governing equations include continuity, momentum and energy equations with Boussinesq approximation were solved simultaneously using appropriate boundary conditions. This study was confined to work out for low-Rayleigh-number flows. The simulation results were compared with experimental data to validate the accuracy of the CFD work. The CFD results were in excellent agreement with experimental data from the literature. In addition, the effective parameters such as the aspect-ratio and fracture distribution on natural convection were investigated. The results indicated that increasing the aspect-ratio of fracture caused an increase of the maximum velocity in the fracture and temperature profile in the model was affected by fractures communication. Furthermore, the effect of porous medium with a tilted fracture through it was discussed. [ABSTRACT FROM AUTHOR]

Molecular dynamics (MD) simulations were performed to compute the properties of the ionic liquid 1-hexyl-3-methylimidazolium hexafluorophosphate, [hmim][PF 6 ], at three different temperatures (298, 323, and 348 K) and atmospheric pressure. Thermodynamic, structural, and dynamical properties, such as average density, isobaric thermal expansion coefficient, isothermal compressibility factor, radial distribution function (RDF), spatial distribution function (SDF), mean square displacement (MSD) and velocity autocorrelation function (VACF) were computed and interpreted. The ionic self-diffusion coefficients were calculated using both the Einstein and Green–Kubo formulas and it was found that the cation diffuses faster than the anion and contributes more in the electric current. The ionic self-diffusion coefficients obtained from the Green–Kubo method agreed reasonably well with the experimental data in compared to the Einstein method. Also, the self-diffusion coefficients obtained from the two methods were used to calculate the ionic conductivity from the Nernst–Einstein equation. The effects of the system size and simulation run-time on determining diffusivity using the Einstein method were also investigated. The RDFs show that anions interact preferentially with the cation ring especially in direction of the acidic hydrogen atom of the imidazolium ring. This interaction was identified as hydrogen bonding interaction and observed using SDF. [ABSTRACT FROM AUTHOR]

The reduction of iron ions concentration from copper electrowinning electrolyte solution in copper solvent extraction and electrowinning process, is important to maintain good current efficiency. In this study both chemical precipitation (hydroxide and jarosite) and ion exchange methods were investigated using industrial copper raffinate and electrowinning solutions from Sarcheshmeh copper complex, Iran. Batch precipitation and adsorption tests were initially performed before, a fixed bed column was investigated for iron removal by ion exchange. Batch results indicated that with increasing the pH and dilution, improved the iron removal by chemical precipitation methods. Hydroxide and jarosite precipitations were performed efficiently at pHs of 3 and 2 and temperatures of 70 °C and 95 °C respectively. The iron removal efficiency was greater with jarosite precipitation (∼70%) compared to hydroxide (∼20%) for a particular pH (2). Diluting by 50% increased the removal efficiency up to 150%. Ion exchange results indicated that pH and dilution did not have a significant effect on the efficiency with this method and it practically performed at ambient temperatures. The batch equilibrium and kinetics experiments were performed with Purolite S957 resin and the results showed that the Sips isotherm (the maximum adsorption capacity was 42 mg/g) and both the pseudo-nth order (k ad = 0.00083 mg 1−n /g 1−n ·s and n = 1.92) and Langmuir-Freundlich kinetics models ( k a LF = 0.08 mL min - 1 mg - 1 , k d LF = 0.12 min - 1 and n = 0.12) were able to predict the equilibrium and kinetics data. In the fixed bed column experiments, the effects of parameters such as the volumetric flow rate and bed height on the breakthrough curves were studied. The iron removal efficiency for the industrial solution which included impurities was less than for synthetic solutions. The results showed that the resin selectively removed the iron ions but did not decrease the copper concentration and used resin was completely regenerated by hydrochloric acid (the amount of 5 mL/g of resin and concentration of 30 wt%) over several regeneration did not significantly alter the sorption capacity. Finally, a mathematical model based on chemical sorption was used to predict the experimental breakthrough curves data and results showed this model accurately predicted the experimental breakthrough curves. Overall, ion exchange was more efficient at iron removal than chemical precipitation. [ABSTRACT FROM AUTHOR]

Background: In a c-VEP BCI setting, test subjects can have highly varying performances when different pseudorandom sequences are applied as stimulus, and ideally, multiple codes should be supported. On the other hand, repeating the experiment with many different pseudorandom sequences is a laborious process. Aims: This study aimed to suggest an efficient method for choosing the optimal stimulus sequence based on a fast test and simple measures to increase the performance and minimize the time consumption for research trials. Methods: A total of 21 healthy subjects were included in an online wheelchair control task and completed the same task using stimuli based on the m-code, the gold-code, and the Barker-code. Correct/incorrect identification and time consumption were obtained for each identification. Subject-specific templates were characterized and used in a forward-step first-order model to predict the chance of completion and accuracy score. Results: No specific pseudorandom sequence showed superior accuracy on the group basis. When isolating the individual performances with the highest accuracy, time consumption per identification was not significantly increased. The Accuracy Score aids in predicting what pseudorandom sequence will lead to the best performance using only the templates. The Accuracy Score was higher when the template resembled a delta function the most and when repeated templates were consistent. For completion prediction, only the shape of the template was a significant predictor. Conclusions: The simple and fast method presented in this study as the Accuracy Score, allows c-VEP based BCI systems to support multiple pseudorandom sequences without increase in trial length. This allows for more personalized BCI systems with better performance to be tested without increased costs. [ABSTRACT FROM AUTHOR]

[Display omitted] • A combination of DSPE and DLLME was developed for the extraction of DOACs. • A ternary mixture of sorbents was used in DSPE for the effective adsorption of DOACs. • HPLC-DAD was used for determination of the analytes. • LODs and LOQs were achievable at ng mL−1 level. • Greenness, simplicity, and being effective were advantages of the method. In this report, combination of a mixed mode dispersive solid phase extraction with dispersive liquid–liquid microextraction has been performed in order to the effective isolation of three anticoagulant drugs (anagrelide, betrixaban, and apixaban) from urine sample. The extracted drugs were quantified by high performance liquid chromatography–diode array detector. Firstly, analytes were adsorbed onto a mixture of octadecylsilane, graphitized carbon black, and primary secondary amine sorbents which their composition was obtained by a simplex centroid design. To increase the adsorption efficiency, sonication of the solution and sorbents mixture was performed. The loaded analytes onto the sorbent surface were washed employing a water–miscible organic solvent which was utilized as a disperser in microextraction process. The microextraction step was done using a magnetic ionic liquid (as an extractant) and the droplets were sedimented at the bottom of tube with the aid of an external magnetic field. Satisfactory analytical results such as wide linear ranges (0.21–250 µg/L), high enrichment factors (223–247) and extraction recoveries (76–84 %), and low limits of detection (0.04–0.06 µg/L) and quantification (0.16–0.21 µg/L) were obtained using the optimum experimental situations. Lastly, the offered procedure was utilized for the quantification of the opted analytes in urine samples. [ABSTRACT FROM AUTHOR]

In dissolution processes, during geometry evolution, the two-phase interface is continuously changed. For tracking the position of the interface, the method of combining VOF with curved boundary schemes was presented in this research. Since the combination would be rather complex, in addition to the original approach, a simplified approximate approach was also introduced. Further, for simulating heterogeneous dissolution in lattice Boltzmann (LB) framework, the volume of pixel (VOP) method has been widely used by researchers. Since the area of the solid-fluid interface is not captured by this method, the study of its validity was also presented in this research. For this purpose, simulations of calcium carbonate dissolution by hydrochloric acid in simple and complex porous media were performed. In addition to the VOP method, the volume of fluid (VOF) method in which the solid-fluid interface is tracked, was also applied for all cases of simulations. The results revealed that from a dissolution perspective, the performance of the VOF-curved boundary combination is essentially similar to that of the VOF-bounce back combination. However, the algorithm of bounce back was found to be more than 10% computationally efficient. Also, comparison of the outcomes from VOP and VOF indicated that VOP intrinsically overestimates the surface area of reactions by about 25–35%, which fictitiously leads to 20–30% higher reaction rates and nearly 20–30% less dissolution times. Hence, it was deduced that the temporal outcomes of VOP may not be valid. However, from a non-temporal perspective, the dissolution patterns of both methods were found to be essentially similar. • VOF was used to track altering solid-fluid interfaces in heterogeneous dissolutions. • Method of combining VOF and curved boundary schemes in LBM framework was presented. • Results of VOF were compared with VOP and the validity of VOP method was discussed. • A simplified curved boundary approach for combination with VOF was suggested. • Performance of curved and bounce back schemes in combination with VOF were compared. [ABSTRACT FROM AUTHOR]

[Display omitted] • An analytical method based on DµSPE–HPLC–MS/MS was developed. • For the first time, a vitamin-based metal organic framework was exploited as sorbent in DµSPE. • The suggested method was used for the analysis of PAT and OCT A in fruit juices. • LODs and LOQs were achievable at ng L−1 level. Herein, for the first time, a vitamin-based metal organic framework is synthesized from vitamin B 3 (as a bio linker) and cobalt ions (as a metallic center) and employed as an efficient sorbent in dispersive micro solid phase extraction of patulin and ochratoxin A from fruit juice samples. The extracted analytes are quantitatively analyzed using high performance liquid chromatography-tandem mass spectrometry. In this work, after synthesizing the sorbent, it was characterized using X-ray diffraction, Fourier transform infrared spectrophotometry, scanning electron microscopy, nitrogen adsorption/desorption, and energy-dispersive X-ray spectroscopy. In the following, it was used as an efficient sorbent in the offered microextraction method and numerous parameters that could affect extraction efficiency of the method were investigated and optimized using response surface methodology. Based on the method validation results, limits of detection and quantification were 39.6 and 131.7 ng L−1 for patulin, and 24.8 and 82.6 ng L−1 for ochratoxin A, respectively. The extraction recoveries for patulin and ochratoxin A were 75 and 87%, respectively. Repeatability of the suggested approach, expressed as relative standard deviations, were equal to or<5% (at a concentration of 250 ng L−1 of each analyte). Also, environmentally friendly synthesis of the metal organic framework (using vitamin B 3 as a linker, water as the reaction solvent, and mild conditions) and usage low amount or volumes of the sorbent and organic solvents in the microextraction procedure were other advantages of the current work. [ABSTRACT FROM AUTHOR]

In this study, a rapid, simple, and efficient sample preparation method based on continuous dispersive liquid–liquid microextraction has been developed for the extraction and preconcentration of aryloxyphenoxy-propionate herbicides from aqueous samples prior to their analysis by gas chromatography–flame ionization detection. In this method, two parallel glass tubes with different diameters are connected with a teflon stopcock and used as an extraction device. A mixture of disperser and extraction solvents is transferred into one side (narrow tube) of the extraction device and an aqueous phase containing the analytes is filled into the other side (wide tube). Then the stopcock is opened and the mixture of disperser and extraction solvents mixes with the aqueous phase. By this action, the extraction solvent is dispersed continuously as fine droplets into the aqueous sample and the target analytes are extracted into the fine droplets of the extraction solvent. The fine droplets move up through the aqueous phase due to its low density compared to aqueous phase and collect on the surface of the aqueous phase as an organic layer. Finally an aliquot of the organic phase is removed and injected into the separation system for analysis. Several parameters that can affect extraction efficiency including type and volume of extraction and disperser solvents, sample pH, and ionic strength were investigated and optimized. Under the optimum extraction conditions, the extraction recoveries and enrichment factors ranged from 49 to 74% and 1633 to 2466, respectively. Relative standard deviations were in the ranges of 3–6% (n = 6, C = 30 μg L −1 ) for intra-day and 4–7% (n = 4, C = 30 μg L −1 ) for inter-day precisions. The limits of detection were in the range of 0.20–0.86 μg L −1 . Finally the proposed method was successfully applied to determine the target herbicides in fruit juice and vegetable samples. [ABSTRACT FROM AUTHOR]

• A new vitamin–based metal organic framework was synthesized and used as the sorbent in DµSPE. • Dispersive micro solid phase extraction of aflatoxins from commercial soymilk was developed. • HPLC-MS/MS was used for determination of aflatoxins. • Greenness, low cost, simplicity, and being effective are advantages of the method. In the current work, for the first time, a vitamin–based metal–organic framework constructed from cobalt ions and vitamin B 3 has been used as a sorbent in dispersive micro–solid–phase extraction. The proposed method was used to extract and enrich aflatoxins (B 1 , B 2 , G 1 , and G 2) from soy milk samples before their quantification by high performance liquid chromatography–tandem mass spectrometry. In this work, first the metal–organic framework was synthesized and characterized using techniques such as X–ray diffraction, Fourier transform infrared spectrophotometry, scanning electron microscopy, nitrogen adsorption/desorption, and energy–dispersive X–ray spectroscopy. Then it was used as an efficient sorbent in the proposed dispersive micro–solid–phase extraction. For this purpose, after precipitating the proteins of soy milk sample with the aid of trichloroacetic acid, the supernatant phase was taken, mixed with the synthesized sorbent, and vortexed. After centrifuging, the analytes loaded on the adsorbent were eluted with methanol to transfer them into an organic phase which was compatible with the subsequently employed separation system. The adsorption capacity of the synthesized MOF for aflatoxins B 1 , B 2 , G 1 , and G 2 were 0.77, 0.83, 0.70, and 0.54 mg g–1, respectively. Under the best experimental situations, satisfactory outcomes including acceptable extraction recoveries (64–75%), low limits of detection (11.3–48.2 ng L–1) and quantification (42.8–161.6 ng L–1), and good repeatability (relative standard deviations equal or less than 4.0 and 4.7% for intra– and inter– day precisions, respectively) were obtained. In addition, green synthesis of the metal–organic framework (using vitamin B 3 as a linker, water as the reaction solvent, and mild conditions) and usage low amount or volume of the adsorbent and organic solvents during the extraction process were the other beneficial aspects of this work which caused the suggested analytical method to be environmentally friendly. [ABSTRACT FROM AUTHOR]

In this paper, the problem of coarse timing synchronization in orthogonal frequency-division multiplexing (OFDM) systems is investigated, and two new timing metrics with better performance are presented. The new metrics take advantage of two novel differential normalization functions that are based on the fourth-order statistics and are designed depending on the value of carrier frequency offset (CFO). The proposed timing metrics are theoretically evaluated using two different class separability criteria. It is shown that the new schemes considerably increase the difference between the correct and wrong timing points in comparison with previous methods. The computational complexity of the new methods is obtained, and their superior detection performances are also demonstrated in terms of probabilities of false alarm and missed detection. The results indicate that due to a significant improvement in missed detection probability (MDP), the new methods offer a considerably wider range of acceptable thresholds. [ABSTRACT FROM PUBLISHER]

Copper electrowinning is the process of winning a high purity copper from an aqueous pregnant liquor acid electrolyte in the presence of impurities. In this study, a three-dimensional, steady and two-phase (liquid–gas) computational fluid dynamics (CFD) simulation was applied, together with experimental field measurements, to investigate the performance of an industrial electrowinning cell in the Sarcheshmeh Copper Complex, Iran. This simulation was based on Eulerian–Eulerian method. The continuity and momentum equations with inclusion of buoyancy, drag, turbulent dispersion and concentration-related buoyancy forces were solved by the finite volume method. In order to calculate the velocity distribution in the cell, the k–ω turbulence flow model has been used. To find the concentration distribution of copper, the transport equation of copper ions was solved. There was a good agreement between the simulation results and the experimental measured data of the electrowinning cell. After validation of the model, the effects of electrical current density, volumetric flow rate of feed and the distance between the electrodes were studied on the performance of the cell and copper concentration distribution. The simulation results show that there are two upward flows in the cell, one is near the anode because of oxygen generation and the other is near the cathode due to depletion of copper ions from the electrolyte and buoyancy force. In the middle of the cell, the electrolyte recirculation zone causes a downward flow. Increasing electrical current density decreases copper concentration near the cathode and increases gas volume fraction near the anode, which is in accordance with Faraday's Law. With decreasing volumetric flow rate and distance between the electrodes, copper mass concentration on the cathode decreases. [ABSTRACT FROM AUTHOR]

Permeability estimation has a significant impact on petroleum fields operation and reservoir management. Different methods were proposed to measure this parameter, which some of them are inaccurate, and some others such as core analysis are cost and time consuming. Intelligent techniques are powerful tools to recognize the possible patterns between input and output spaces, which can be applied to predict reservoir parameters. This study proposed a new approach based on multi-gene genetic programming (MGGP) to predict permeability in one of the heterogeneous oil reservoirs in Iran. The MGGP model with artificial neural networks (ANNs), adaptive neuro-fuzzy inference system (ANFIS) and genetic programming (GP) model were used to predict the permeability and obtained results were compared statistically. The comparison of results showed that the MGGP model can be applied effectively in permeability prediction, which gives low computational time. Furthermore, one equation based on the MGGP model using well log and core experimental data was generated to predict permeability in porous media. [ABSTRACT FROM AUTHOR]

Many theoretical and experimental studies on heat transfer and flow behavior of nanofluids have been done and the results show that nanofluids significantly increase heat transfer. Nevertheless, there is no accurate understanding from the effect of different mechanisms on nanofluid heat transfer. Computer simulations are a suitable tool for description of physical mechanisms in many processes. In this study, molecular dynamics simulation was used to investigate the effect of nanoparticle aggregation on thermal properties of water-silicon dioxide nanofluid, specifically its thermal conductivity. For calculating nanofluid thermal conductivity a combination of two equilibrium and non-equilibrium molecular dynamics simulations was performed to calculate the specific heat and thermal diffusivity of the nanofluid, respectively. Simulations were performed in NVT ensemble and spherical coordinate. The model was validated by comparison of thermal properties of water base fluid with experimental data in four various temperatures. Results also were compared with theoretical models such as HC model for nanofluid. To investigate the effect of nanoparticle aggregation, two cases of constant and variable volume fractions (i.e. 1.5, 3 and 4.5%) at temperature of 308 K were considered. The results showed that when the aggregation occurs with increasing nanoparticle concentrations, there are an increase in the thermal conductivity and thermal diffusivity of the nanofluid and a decrease in its specific heat. Moreover, when aggregation takes place at constant nanoparticle concentration, the specific heat of nanofluid with suspended nanoparticles did not change with respect to nanofluid with aggregated nanoparticles, but its diffusivity and thermal conductivity increase. [ABSTRACT FROM AUTHOR]

A new sample preparation method named in–syringe gas–assisted density tunable dispersive liquid phase microextraction based on solidification of floating organic droplet has been introduced. This method was coupled with high–performance liquid chromatography–tandem mass spectrometry and used for the extraction and quantification of amikacin in plasma and exhaled breath condensate (EBC) samples of the patients receiving amikacin. In the proposed approach, an inert gas is bubbled into a syringe barrel containing aqueous solution of the analyte and a mixture of low density extraction solvent and volatile density modifier. Consequently, the density modifier is evaporated and the analyte is migrated into the released extractant droplets. Basic parameters affecting efficiency of the developed method were optimized. Under optimum conditions, the method limits of detection were 0.06 and 0.29 ng/mL in EBC and plasma, respectively. The extraction recoveries were 90% and 87% in EBC and plasma, respectively. Also, the obtained relative standard deviations were below 9.5% and 9.8% for EBC and plasma, respectively. Considering these results, the developed method provides a quick and efficient way to determine amikacin in patients' biological fluids and can be used widely in drug monitoring and clinical studies. [ABSTRACT FROM AUTHOR]

Dissolution in fractures and porous media is of great importance to different aspects of the geothermal science and petroleum industry. This numerical study aimed to determine the initial phase of dissolution growth as the breakthrough time and the acid penetration length in a calcite fracture. The dissolution rate was considered as a function of temperature based on 3D numerical simulations to estimate more valid and reliable results, especially in wells at higher bottom-hole temperatures. The heat transfer model was coupled with a reactive transport model by applying the OpenFOAM toolkit based on isothermal and non-isothermal models. The dissolution evolution was simulated considering the isothermal model with the average temperature between the incoming fluid and fracture surfaces and also based on a non-isothermal model. The comparison of dissolution process results obtained from these two models showed lower dissolution rate for the non-isothermal model with a remarkable longer breakthrough time. Accordingly, a non-isothermal model would be a more reliable model for estimating fracture productivity. The results also indicated the inverse effect of temperature on the dissolution values of calcite formation. In other words, increasing the temperature caused a shorter penetration length and a longer breakthrough time eventually leadings to a slower dissolution rate. [ABSTRACT FROM AUTHOR]

[Display omitted] • A method for the implementation of Robin boundary condition in 2D LBM is introduced. • The method suggests using a coupling of Taylor expansion and counter-slip approach. • The method can impose nonlinear reaction kinetics in lattice Boltzmann framework. • The method can impose surface radiation condition in lattice Boltzmann framework. • Order of convergence rate is a function of the nonlinearity of the condition. Implementation of nonlinear boundary conditions like nth-order surface reactions or surface radiation heat transfer has not been investigated in lattice Boltzmann (LB) framework. This study presents a novel kinetic level method for their implementation. The method couples Taylor expansion of the conditions with counter-slip approach to find unknown distribution functions at boundary nodes. The proposed scheme guarantees the locality and orientation independency of formulations. To evaluate the proposed scheme performance, several 1D and 2D test cases were simulated by D2Q9 LBM and the outcomes were compared with analytical and numerical solutions. The geometry evolution by nth-order surface reaction was investigated for dissolutions in a simple fracture and a spherical carbonate particle in a channel. The results demonstrated the method performs promisingly in terms of accuracy. The convergence rate of scheme based on the results from l2-norm analyses showed first or second-order rates of convergence, depending on constraint's degree of nonlinearity. [ABSTRACT FROM AUTHOR]

• To improve micromixer performance, CFD, DOE, MCDM and four meta-heuristic algorithms were combined. • 20 micromixers with different dimensions based on DOE for three different baffle shapes are simulated by CFD. • Two models including the mixing index and pressure drop are obtained by RSM. • The obtained models are optimized by four meta-heuristic algorithms to achieve the micromixers with high performance. • MOPSO algorithm generated more optimal designs, which has created the most mixing with the least pressure drop. Micromixers are devices that have the task of mixing on a small scale. In this study, to improve the mixing index in micromixers with minimum pressure drop, the optimal values of the affecting factors on the micromixer performance were obtained by using computational fluid dynamics (CFD), design of experiment (DOE), meta-heuristic algorithms and multi-criteria decision making (MCDM). The most influential factors on the performance of micromixers are Reynolds number, blockage ratio and the ratio of the distance between baffles to baffle diameter, which is examined in the different baffle shapes. The dimensionless ratios obtained from these parameters, which were achieved by using the mentioned methods, significantly improved the efficiency of micromixers and they are facilitators and necessary for future studies. The obtained mathematical models from DOE were optimized by meta-heuristic algorithms and then the results of algorithms were compared with each other by four evaluation criteria. It was shown multi-objective Particle Swarm Optimization (MOPSO) had the best performance in presenting the preferred solutions. The designs were ranked among the members of the Pareto front by MCDM. The preferred solution with the ratio of mixing index to pressure drop equal to 0.78 was the most optimal case. [Display omitted] [ABSTRACT FROM AUTHOR]

A venturi scrubber is one of the most important devices for air pollution control. Although there are different models for predicting the pressure drop in venturi scrubbers, most of them have some defects and cannot predict the pressure drop correctly. In this study, for the first time, an Eulerian-Eulerian computational fluid dynamics (CFD) model is combined with a population balance equation to predict the pressure drop in venturi scrubbers. This simulation takes into account a multiple size group model for droplet dispersion and droplet size distribution, which is based on a population balance equation. Flow field has been calculated by solving the time averaged continuity and Navier-Stokes equations along with the standard k- ε turbulence model. The equations included drag, turbulent dispersion, and buoyancy forces. The calculated pressure drop with and without considering the population balance equation was compared with the experimental data to evaluate the accuracy of the CFD modeling. The size distribution of droplets in the venturi scrubber was studied at different points for different liquid to gas ratios and throat gas velocities. The results show that the maximum break-up of droplets happens at the liquid injection point. Finally, the effects of nozzle diameter and nozzle arrangement on pressure drop in venturi scrubbers were investigated. [ABSTRACT FROM AUTHOR]

Abstract: This paper presents a novel approach of permeability prediction by combining cuckoo, particle swarm and imperialist competitive algorithms with Levenberg–Marquardt (LM) neural network algorithm in one of heterogeneous oil reservoirs in Iran. First, topology and parameters of the Artificial Neural Network (ANN) as decision variables were designed without the optimization method. Then, in order to improve the effectiveness of forecasting when ANN was applied to a permeability predicting problem, the design was performed using Cuckoo Optimization Algorithm (COA) algorithm. The validation test result from a new well data demonstrated that the trained COA–LM neural model can efficiently accomplish permeability prediction. Also, the comparison of COA with particle swarm optimization and imperialist competitive algorithms showed the superiority of COA on fast convergence and best optimum solution achievement. [Copyright &y& Elsevier]

In this study, the cuckoo optimization algorithm was used to design a fuzzy logic model for determination of the compressive strength of 28-day-old concrete. Experimental results from 50 concrete mixtures were loaded into the fuzzy logic model for training, and the model was then optimized by use of the cuckoo optimization algorithm. Input variables of the fuzzy logic model are water-to-cement weight ratio and coarse aggregate-to-fine aggregate weight ratio; the output variable is concrete compressive strength. The results obtained from the optimized model were compared with those from an adaptive neuro fuzzy inference system model; they were also validated experimentally. [ABSTRACT FROM AUTHOR]