Ultrasonic cavitation-enabled microfluidic approach toward the continuous synthesis of cesium lead halide perovskite nanocrystals

Ligand assisted reprecipitation(LARP)is a widely used method for cesium lead halide perovskite nanocrystals(NCs)synthesis.Nevertheless,the ultrafast kinetics of LARP,as well as the inefficient transport properties and discontinuity of batch reactors,challenge the particle size control and experimental repeatability.To address these issues,an ultrasonic cavitation-enabled microfluidic approach was developed to achieve the continuous synthesis of cesium lead halide perovskite via LARP.It was found that the mixing between the good solvent and antisolvent in the microchannel was greatly enhanced by intensive ultrasonic cavitation.The mixing time could be reduced to below 10 ms under the irradiation of 35 W ultrasound.By modulating the mixing degree,LARP was proved to be a mixing-sensitive process.The effects of ultrasonic power,ultrasonic treatment time,total flow rate,water additive,and reprecipitation temperature on the synthesis of CsPbBr_(3) NCs were systematically investigated.As compared to CsPbBr_(3) NCs synthesized in the batch reactor,the sample synthesized via the ultrasonic cavitation-enabled microfluidic approach possessed stronger photoluminescence intensity and better repeatability.Moreover,the ultrasonic cavitation-enabled microfluidic approach could also realize the continuous synthesis of cesium lead halide perovskite NCs with different halide compositions to cover a wide visible spectrum(426-661 nm).The ultrasonic cavitation-enabled microfluidic approach paved the way for the large-scale of high-quality cesium lead halide perovskite NCs.

Ultrasonic emulsification: basic characteristics, cavitation, mechanism, devices and application

Emulsion systems are widely applied in agriculture,food,cosmetic,pharmaceutical and biomedical industries.Ultrasound has attracted much attention in emulsion preparation,especially for nanoemulsion,due to its advantages of being eco-friendly,cost-effective and energy-efficient.This review provides an overview for readers to the area of ultrasonic emulsification technology.It briefly introduces and summarizes knowledge of ultrasonic emulsification,including emulsion characteristics,acoustic cavitation,emulsification mechanism,ultrasonic devices and applications.The combination of microfluidics and ultrasound is highlighted with huge advantages in controlling cavitation phenomena and emulsification intensification.A novel scale of dμC^(0.6)/μD^(0.33)−EV is proposed to be able to compare the energy efficiency of emulsion preparation in different devices.

Dosimetric comparison of tomotherapy and volumetric-modulated arc therapy for children with neuroblastoma

Importance:Irradiation treatment for pediatric patients with neuroblastoma represents a major challenge due to the pediatric dose limits for critical structures and the necessity of sufficient dose coverage of the clinical target volume for local control.Objective:To investigate dosimetric differences between tomotherapy(TOMO)and volumetric-modulated arc therapy(VMAT)as retroperitoneal radiotherapy for children with neuroblastoma.Methods:Eight patients who received retroperitoneal radiotherapy for neuroblastoma were selected for comparison of TOMO and VMAT treatment plans.The D min,D max,D mean,D 95,D 2,and D 98 of planning target volume(PTV),conformity index(CI),heterogeneity index(HI),and organs at risk(OARs)parameters were compared.Delivery machine unit(MU)and image-guide radiotherapy solution results were also compared.Results:All patients received a cumulative dose of 19.5 Gy to the PTV.VMAT showed higher CI(0.93±0.02),compared with TOMO(0.87±0.03,P<0.001).Notably,the average PTV HI was significantly better using TOMO(1.05±0.01)than VMAT(1.08±0.02,P=0.003).Compared with VMAT,the D min,D 95,and D 98 all exhibited increases in TOMO;D max variation was less than 1%in TOMO.The D 0.1cc for the spinal cord and D 2cc for the small intestine were better in TOMO in terms of OARs.However,TOMO had more MUs and required a longer delivery time.Interpretation:Both planning techniques are capable of producing high-quality treatment plans.TOMO is superior for PTV coverage,but inferior for CI.TOMO requires extra treatment time;its cost is greater than the cost of VMAT.