Deep eutectic solvents (DESs) as a new kind of green solvents have been used to extract bioactive compounds but there are few applications in extracting chrysoidine dyes. In this study, we developed ...an ultrasonic-assisted extraction method with choline chloride/hydrogen bond donor (ChCl/HBD) DES for the extraction of chrysoidine G (COG), astrazon orange G (AOG), and astrazon orange R (AOR) in food samples. Some experimental parameters, such as extraction time, raw material/solvent ratio, and temperature, were evaluated and optimized as follows: the ratio of ChCl/HBD, 1 : 2 (v/v); the ratio of sample/DES, 1 : 10 (g/mL); extraction time, 20 min; extraction temperature, 50°C. Under the optimized conditions, the limits of detection (μg/mL) were 0.10 for COG and 0.06 for AOG and AOR. The relative standard deviations were in the range of 1.2–2.1%. The recoveries of the three dyes were in the range of 80.2–105.0%. By comparing with other commonly used solvents for extracting chrysoidine dyes, the advantages of DESs proved them to be potential extraction solvents for chrysoidine G, astrazon orange G, and astrazon orange R in foods.
A novel method was developed for the determination of two endocrine‐disrupting chemicals, bisphenol A and 4‐nonylphenol, in vegetable oil by dispersive liquid–liquid microextraction followed by ultra ...high performance liquid chromatography with tandem mass spectrometry. Using a magnetic liquid as the microextraction solvent, several key parameters were optimized, including the type and volume of the magnetic liquid, extraction time, amount of dispersant, and the type of reverse extractant. The detection limits for bisphenol A and 4‐nonylphenol were 0.1 and 0.06 μg/kg, respectively. The recoveries were 70.4–112.3%, and the relative standard deviations were less than 4.2%. The method is simple for the extraction of bisphenol A and 4‐nonylphenol from vegetable oil and suitable for routine analysis.
The numerical modeling of High Temperature Air Combustion (HTAC) could correctly predict the flame and emission characteristics so far, however, the precision is not satisfactory. In this paper, a ...parameter-modified Eddy-Break-Up (EBU) model with a three-step reaction scheme was used to simulate the HTAC process in a furnace of 2m ×2m×6.25m. Reynolds stress model (RSM) is used for the computational fluid dynamics (CFD) simulation. Comparison between experimental data from published papers, the original and modified EBU combustion models demonstrates that a smaller coefficient ‘A’ in the volumetric fuel consumption rate of the EBU model could improve the modelling precision. When ‘A’ is modified to be 1 other than its original value, 4, in the EBU model, the modeling could give improved results of the local distribution of CH4, temperature and NO emission.
Natural ventilation is suitable for application to workshops with heat sources to keep good indoor air quality at lower energy cost. In this paper, the authors numerically investigated the ...buoyancy-driven natural ventilation in a workshop with heat source based on computational fluid dynamics (CFD) method. The effect of the distance between heat source and ground on the air flow and temperature distribution was examined. Results showed that the average air temperature at operation zone could be effectively reduced when the distance between heat source and ground increased. The temperature field in the upper zone of the workshop was improved by diminishing the hot air zone near the ceiling and the waste heat directly going into the operation zone decreased when the distance between heat source and ground increased.
A three-dimensional model of a circular casting mold with a vibrating nucleus generator was established, and the characteristics of temperature and flow fields during the solidification process of ...ferritic stainless steel Cr17 in the casting mold were analyzed using finite element and finite difference methods. A standard k-ε turbulent current model was adopted to simulate the temperature field, and a standard k-ε model in Reynolds-averaged Navier–Stokes equations (RANS) was employed to deal with the flow field. The temperature field diffuses outward with a positive temperature gradient. Low degrees of undercooling can prevent solidified shells from forming rapidly on the surface of the nucleus generator. The temperature perpendicular to the direction of vibration is lower than that in the direction of vibration. The flow field exhibits a heart-shaped distribution and spreads gradually outward. The uniform distribution of grains can be achieved at three different frequencies of vibration. The results show that the degree of undercooling affects the distribution of the temperature field while the frequency of vibration affects the flow field significantly. Under the conditions of undercooling of 540 K and vibration frequency of 1000 Hz, the region perpendicular to the vibration direction of the nucleus generator is the optimum area for equiaxed crystal formation.
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