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To obtain a better insight into comprehending the unusual role of ultrasound frequency and enhance the extraction yield of total anthocyanins (TA) from purple sweet potatoes (PSPs), an approach of wide frequency‐based ultrasound‐assisted extraction (WF‐UAE) was applied to evaluate the influence on the extraction of TA under process parameters at different levels, ultrasound frequency (20–84 kHz), ethanol concentration (20–65%), solvent to solid ratio (10–70 ml/g), ultrasound power (50–280 W), temperature (30–70°C), particle size (0.147–0.908 mm), and treatment time. The results showed that ultrasound frequency has more influence on the extraction yield, followed by temperature, treatment time, and other extraction parameters. The maximum yield of 0.567 ± 0.005 mg/g of TA was obtained at optimized parameters, which was significantly higher than Soxhlet extraction where only 0.324 ± 0.002 mg/g was achieved at 98°C for 720 min, as well as higher than ultrasound‐assisted extraction where only 0.465 ± 0.006 mg/g was obtained at 300 W and 20 kHz for 45 min. The extraction kinetics were performed at different levels of process parameters by Peleg's model. Model constants and equilibrium concentration for different process parameters were predicted. Model validation was done by depicting predicted and experimental values from extracted TA. The obtained values of regression coefficient (R2 > 0.972) and root mean square deviation (RMSD < 0.218) indicated that this model has a good agreement with the experimental results. Novelty impact statement This work is the first to evaluate the effects of ultrasound frequency span a wide range from 20 to 84 kHz and other process parameters on the extraction of TA from PSPs by using an approach of WF‐UAE that was based on a frequency search device with eight extraction tanks controlled by a computer. The application of WF‐UAE technology could not only efficiently extract TA from PSPs, but also be promising for extracting active components from different natural materials in the industry.

In this paper, VO2 thin films with good optical properties are fabricated on practical float glass by magnetron sputtering and a professional annealing method. The near-infrared switching efficiency (NIRSE) of the prepared film reaches 39% (@2000 nm), and its near-infrared energy modulation ability (ΔTir) reaches 10.9% (780–2500 nm). Further, the highest integral visible transmittance Tlum is 63%. The proposed method exhibits good reproducibility and does not cause any heat damage to the magnetron sputtering machine. The crystalline structure of the VO2 film is characterized by X-ray diffraction (XRD). The lattice planes (011) and (−211) grow preferentially (JCPDS 65-2358), and a large number of NaV2O5 crystals are detected simultaneously. The microstructures are characterized by scanning electron microscopy (SEM), and a large number of long sheet crystals are identified. The phase transition temperature is significantly reduced by an appropriate W doping concentration (Tc = 29 °C), whereas excessive W doping causes distortion of the thermal hysteresis loop and a reduction in the NIRSE. Oxygen vacancies are created by low pressure annealing, due to which the phase transition temperature of VO2 film decreases by 8 °C. The addition of an intermediate SiO2 layer can prevent the diffusion of Na+ ions and affect the preparation process of the VO2 thin film.

The growth mechanism of Cu6Sn5 intermetallic compound (IMC) at Sn/Cu interface reflowed under 250 ℃, 275 ℃, and 300 ℃ for a duration of 60s and undergoing highly pressurized air action(HP), water cooling(WC), air cooling(AC) or furnace cooling(FC) in the aftermath has been outlined. In addition, synchrotron radiation imaging technique has been utilized to in-situ observe interfacial Cu6Sn5 grains growth. It has been revealed that the morphologies of Cu6Sn5 grains under HP and AC are both scalloplike, whereas the samples processed with HP and FC bear plane structure and prismatic morphologies.These revelations indicate the secondary growth of Cu6Sn5 grains during the cooling stage as the significant determinant of the final IMC morphology. Thus, continuous growth on the rough surface (M1), spiral dislocation growth (M2), and 2D nucleation and growth (M3), have been proposed to explain the 2 observed morphologies of interfacial Cu6Sn5 grains. M1 has been recognized as the principal mechanism responsible for IMC morphology undergoing water cooling, whereas combination of M1 and M2 decide the morphological feature of interface resulting from air cooling. Finally, all of the three mechanisms (M1, M2 and M3) account for the IMC morphology corresponding to furnace cooling. As all of these three growth mechanisms are affected by the degree of supercooling (ΔT), it is inferred that the ΔT can influence the secondary nucleation of IMC at the cooling stage. With the fact that the homogeneous nucleation occurs at larger ΔT, and the relative favorability for heterogeneous nucleation at smaller ΔT; the growth mechanisms can be mapped with the degree of undercooling. Consequently, the IMC growth mechanisms proposed and their association with ΔT, can be used to obtain an appropriate thickness and morphology of IMC to improve the reliability of solder joints.