Novel sponge-like molecularly imprinted mesoporous silica material for selective isolation of bisphenol A and its analogues from sediment extracts

Bisphenol A (BPA) imprinted sponge mesoporous silica was synthesized using a combination of semi-covalent molecular imprinting and simple self-assembly process. The molecularly imprinted sponge mesoporous silica (MISMS) material obtained was characterized by FT-IR, scanning electron microscopy, transmission electron microscopy, and nitrogen adsorption–desorption measurements. The results show that the MISMS possessed a large specific surface area (850.55 m² g⁻¹) and a highly interconnected 3-D porous network. As a result, the MISMS demonstrated a superior specific adsorption capacity of 169.22 μmol g⁻¹ and fast adsorption kinetics (reaching equilibrium within 3 min) for BPA. Good class selectivity for BPA and its analogues (bisphenol F, bisphenol B, bisphenol E and bisphenol AF) was also demonstrated by the sorption experiment. The MISMS as solid-phase extraction (SPE) material was then evaluated for isolation and clean-up of these bisphenols (BPs) from sediment samples. An accurate and sensitive analytical method based on the MISMS–SPE coupled with HPLC–DAD has been successfully established for simultaneous determination of five BPs in river sediments with detection limits of 0.43–0.71 ng g⁻¹ dry weight (dw). The recoveries of BPs for lyophilizated sediment samples at two spiking levels (50 and 500 ng g⁻¹ dw for each BP) were in the range of 75.5–105.5% with RSD values below 7.5%.     

Extraction and Analysis of Six Effective Components in Glycyrrhiza uralensis Fisch by Deep Eutectic Solvents (DES) Combined with Quantitative Analysis of Multi-Components by Single Marker (QAMS) Method

Deep eutectic solvents (DESs) are green organic solvents that have broad prospects in the extraction of effective components of traditional Chinese medicine. This work employed the quantitative analysis of multi-components by a single marker (QAMS) method to quantitatively determine the six effective components of glycyrrhizic acid, liquiritin, isoliquiritin apioside, liquiritigenin, isoliquiritin, and glycyrrhetinic acid in Glycyrrhiza uralensis, which was used for comprehensive evaluation of the optimal extraction process by DESs. First, Choline Chloride: Lactic Acid (ChCl-LA, molar ratio 1:1) was selected as the most suitable DES by comparing the extraction yields of different DESs. Second, the extraction protocol was investigated by extraction time, extraction temperature, liquid-to-material ratio, molar ratio, and ultrasonic power. The Box–Behnken design (BBD) combined with response surface methodology (RSM) was used to investigate the optimal DES conditions. The result showed that the best DES system was 1.3-butanediol/choline chloride (ChCl) with the molar ratio of 4:1. The optimal extraction process of licorice was 20 mL/g, the water content was 30%, and the extraction time was 41 min. The comprehensive impact factor (z) was 0.92. At the same time, it was found that the microstructure of the residue extracted by the eutectic solvent was more severely damaged than the residue after the traditional solvent extraction through observation under an electron microscope. The DES has the characteristics of high efficiency and rapidity as an extraction solution.     

Investigation of Alternative Length Scale Substitutions in Detached-Eddy Simulation

The objective of this work is the comparison of three different DES-style hybrid RANS/LES implementations based on the Wilcox k– model. The three variants are designed to investigate alternative methods of substitution of the DES length scale within the background Reynolds Averaged Navier-Stokes (RANS) model. Basis for comparison is provided by both the idealised case of the decay of isotropic turbulence (DIT) as well as the practical case of the massively separated, turbulent flow around an airfoil at high angle of attack. The results of the investigations are discussed in detail, the outcome of which is an emphasis of the importance of DIT as a method for calibration, as well as of the relative freedom with which alternative DES-inspired approaches can be implemented for flows of practical relevance.     

弯管和文丘里管组合燃烧器的颗粒分布特性

本文给出一种弯管和文丘里管组合结构的新型浓淡煤粉燃烧器,并分别对弯管、文丘里管和这种弯管和文丘里管组合结构燃烧器内的气固两相流动进行了数值模拟。采用Euler-Lagrange方法和离散相模型（DPM）研究气固两相流动,气相湍流采用分离涡（DES）模拟方法,固相湍流采用离散随机游动（DRW）模型。结果表明,这三种结构对...     

基于DES方法的平板孤立冷却孔数值模拟研究

本文运用DES(Detached-Eddy Simulation)分离涡方法,对吹风比为0.51和1.04的平板孤立直圆孔和弯圆孔下游的换热特性和漩涡结构进行了数值研究,并简要分析了下游涡量场的结构。模拟结果显示,预测的壁面温度场的趋势与实验值吻合较好;与RANS方法相比,DES方法得到了更加丰富的流场细节和旋涡结构,同时再现了冷却孔下游具有流场的间歇性,对进一步理解和研究冷却孔下游流场内的旋涡结构提供了参考。     

Evaluation of linear and nonlinear convection schemes on multidimensional non‐orthogonal grids with applications to KVLCC2 tanker

Almost all evaluations of convection schemes reported in the literature are conducted using simple problems on uniform orthogonal grids; thus, having limited contribution when solving industrial computational fluid dynamics (CFD), where the grids are usually non‐orthogonal with distortions. Herein, several convection schemes are assessed in uniform and distorted non‐orthogonal grids with emphasis on industrial applications. Linear and nonlinear (TVD) convection schemes are assessed on analytical benchmarks in both uniform and distorted grids. To evaluate the performance of the schemes, four error metrics are used: dissipation, phase and L₁ errors, and the schemes' effective order of accuracy. Qualitative and quantitative deterioration of these error metrics as a function of the grid distortion metrics are investigated, and rigorous verifications are performed. Recommendations for effective use of the convection schemes based on the range of grid aspect ratio (AR), expansion ratio (ER) and skewness (Q) are included. A ship hydrodynamics case is studied, involving a Reynolds averaged Navier–Stokes simulation of a bare‐hull KVLCC2 tanker using linear and nonlinear convection schemes coupled with isotropic and anisotropic Reynolds‐stress (ARS) turbulence models using CFDShip‐Iowa v4. Predictions of local velocities and turbulent quantities from the midships to the nominal wake plane are compared with experimental fluid dynamics (EFD), and rigorous verification and validation analyses for integral forces and moments are performed for 0° and 12° drift angles. Best predictions are observed when coupling a second‐order TVD scheme with the anisotropic turbulence model. Further improvements are observed in terms of prediction of the vortical structures for 30° drift when using TVD2S‐ARS coupled with DES. Copyright © 2009 John Wiley & Sons, Ltd.     

Novel and Rapid Deep Eutectic Solvent (DES) Homogeneous Liquid–Liquid Microextraction (HLLME) with Flame Atomic Absorption Spectrometry (FAAS) Detection for the Determination of Copper in Vegetables

Novel and fast deep eutectic solvent (DES)-based homogeneous liquid–liquid microextraction (HLLME) was applied for the extraction of copper from vegetable samples followed by flame atomic absorption spectrometry (FAAS). 1,5-diphenyl carbazone (DPC) was used as the chelating agent, and a DES was used as the extraction media. The utilized DES was based on benzyl triphenyl phosphonium bromide and ethylene glycol in a 1:8?mole ratio. The phase separation phenomenon was occurred by changing of sample temperature. Several factors influencing the extraction efficiency were investigated and optimized. Under the optimized conditions, an enhancement factor of 64 was obtained. The limit of detection, based on three signal-to-noise ratio, and limit of quantification were found to be 0.13?µg L^?1 and 5.0?µg L^?1, respectively. The calibration curve was linear within the range of 5.0–250?µg L^?1 with r² > 0.9957. Intra- and inter-day relative standard deviations (%) of 2.1% and 2.6% were obtained at the concentration of 25?µg L^?1. The accuracy of the proposed method was evaluated by analyzing a tomato leaves certified reference material and the results were to be in agreement with the certified value. Finally, the feasibility of the method was successfully confirmed by determination of copper in spinach, lettuce, broccoli, potato, carrot and parsley samples.     

Photoluminescence measurements in Be-δ-doped back-gated quantum well

We measured the photoluminescence (PL) spectra of a two-dimensional electron system induced in a Be-δ-doped GaAs/AlGaAs quantum well (QW) with a back gate. The electron density is controlled by means of the back-gate voltage. We estimated the electron density using the magneto-optical method and the PL linewidth, and also by undertaking transport measurements. We show that a uniform 2DES as large as 1 mm² is induced by the back-gate operation from 2.5 × 10¹⁰ cm⁻². This experiment indicates that optical measurement with a back-gated QW is advantageous for studying the low-density 2DES.     

Choline chloride – Urea deep eutectic solvent an efficient media for the preparation of metal nanoparticles

Metal nanoparticles are nanosized structures that have different potential applications in biological, chemical, medical, and agricultural fields because of their exotic characteristics. Their size ranges from 1 to 100 nm. Metal nanoparticles are either purer forms of metals (eg: Gold, Silver, Copper, Iron, etc.) or their compounds (eg: sulfides, hydroxides, oxides, etc.). Ionic liquids are generally used in the extraction of nanoparticles but they are challenging because of their indigent bio-degradability, bio-compatibility, and sustainability. So Deep Eutectic Solvent (DES) is reported as an alternative to ionic liquids in the formation of nanoparticles. The DESs are a complex of quaternary ammonium salts and hydrogen donors or metal salt. DESs contain higher non-symmetric ions which have lower lattice energy and hence they have a lower melting point. This research utilizes a novel DES (choline chloride – urea) as an effective solvent to produce mercuric sulfide (HgS), zirconium oxide (ZrO), manganese oxide (MnO), and copper oxide (CuO) nanoparticles. As a result, the production of these metal nanoparticles using Choline Chloride (C₅H₁₄ClNO) – Urea DES can be treated as a promising way in chemical manufacturing. The nanoparticles have been analyzed using Ultra Violet Spectroscopy, Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), Fourier Transform Infrared Spectroscopy (FT-IR), X-Ray Diffraction (XRD) and Energy Dispersive X-Ray Analysis (EDAX).     

Observations of nascent superfluidity in a bilayer two-dimensional electron system at

Single-layer longitudinal and Hall resistances have been measured in a bilayer two-dimensional electron system at ν_T=1 with equal but oppositely directed currents flowing in the two layers. At small effective layer separation and low temperature, the bilayer system enters an interlayer coherent state expected to exhibit superfluid properties. We detect this nascent superfluidity through the vanishing of both resistances as the temperature is reduced. This corresponds to the counterflow conductivity rising rapidly as the temperature falls, reaching by . This supports the prediction that the ground state of this system is an excitonic superfluid.