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.

细胞自噬基因Atg6在涡虫中枢神经系统再生中的功能研究

细胞自噬基因Atg6在细胞自噬过程中发挥重要作用,其功能缺陷影响神经发生。涡虫是研究中枢神经系统(central nervous system,CNS)再生的良好模型,其头部切除后1周就能再生出一个新的头部。因此,研究Atg6基因在涡虫CNS再生中的作用对探究自噬调控神经发生具有重要意义。本研究首次报道了日本三角涡虫(Dugesia japonica)Atg6基因(DjAtg6)的分子特征,并利用RNAi技术研究了其在涡虫CNS再生中作用。结果显示:DjAtg6 cDNA全长1366 bp,编码423个氨基酸。DjATG6含有ATG6/Beclin 1蛋白家族的Coil-Coil结构域和β折叠α螺旋自噬功能结构域。涡虫沿咽前咽后切割后,DjAtg6表达量显著增加,其转录本主要在新再生的脑神经节表达。RNAi-DjAtg6引起涡虫头部再生迟缓、脑神经结构偏小,并下调神经相关基因的表达。此外,本研究还发现,RNAi-DjAtg6不影响涡虫干细胞的增殖,但下调细胞迁移相关基因mmp1和mmp2的表达,且干扰mmp1和mmp2的表达影响涡虫头再生。因此,本研究结果表明,DjAtg6在涡虫CNS再生的组织重构中发挥重要作用,干扰DjAtg6影响涡虫CNS再生可能与细胞迁移有关,其详细的分子机制尚需进行深入研究。

Gas-liquid-liquid slug flow and mass transfer in hydrophilic and hydrophobic microreactors

Gas-liquid-liquid three-phase slug flow was generated in both hydrophilic and hydrophobic microreactors with double T-junctions.The bubble-droplet relative movement and the local mass transfer within the continuous slug and the dispersed droplet were investigated.It was found that bubbles moved faster than droplets under low capillary number(Ca),while droplets moved faster upon the increase of Ca due to the increased inertia.For the first time,we observed that the increased viscosity of droplets fastened the droplet movement.The mass transfer in the continuous slug was dominated by convection,leading to nearly constant global mass transfer coefficient(k_(L)a);while that in the dispersed droplet was dominated by diffusion,resulting in k_(L) decreasing along the channel.Such features are analogical to the corresponding gas-liquid or liquid-liquid two-phase slug flow,but the formation of bubble-droplet clusters caused by relative movement lowered the absolute mass transfer coefficient.These results provide insights for the precise manipulation of gas-liquid-liquid slug flow in microreactors towards process optimization.

Using expansion units to improve CO_(2) absorption for natural gas purification——A study on the hydrodynamics and mass transfer

The usage of capillary tubes for CO_(2) absorption suffers from small re sidence time,which leads to reduced performance for large throughput.This work presents a method of connecting expansion units to capillary tubes to serve as a residence time delayer.The effect of the expansion unit on gas-liquid hydrodynamics,pressure drop and mass transfer coefficient(k_(L)a) are investigated under various operating pressures up to 4.0 MPa,for both physical and chemical absorption.A novel periodic jetting flow is found in the expansion unit,which can intensify the CO_(2) absorption.Experimental results show that the strategy can significantly decrease the pressure drop while maintaining the absorption performance to a large extent.The overall k_(L)a for physical and chemical absorption are correlated to pressure drop,respectively.Besides,CO_(2) loading in rich absorbents increases dramatically compared to literature studies with only micromixers or capillary tubes,which is bene ficial to regenerate solvent.The study verifies the concept that pre-treatment with water can largely reduce the usage of amine s,and can also provide a guide for process design in natural gas purification such as biogas recovery.

High rodent abundance increases seed removal but decreases scatter-hoarding and seedling recruitment along an elevational gradient

The distributions of small rodents in mountainous environments across different elevations can provide important information regarding the effects of climate change on the dispersal of plant species.However,few studies of oak forest ecosystems have compared the elevational patterns of sympatric rodent diversity,seed dispersal,seed bank,and seedling abundance.Thus,we tested the differences in the seed disperser composition and abundance,seed dispersal,seed bank abundance,and seedling recruitment for Quercus wutaishanica along 10 elevation levels in the Taihang Mountains,China.Our results provide strong evidence that complex asymmetric seed dispersal and seedling regeneration exist along an elevational gradient.The abundance of rodents had a significant negative correlation with the elevation and the seed removal rates peaked and then declined with increasing elevation.The seed removal rates were higher at middle and lower elevations than higher elevations but acorns were predated by 5 species of seed predators at middle and lower elevations,and thus,there was a lower likelihood of recruitment compared with those dropped beneath mother oaks at higher elevations.More importantly,the number of individual seeds in the seed bank and seedlings increased with the elevation,although dispersal services were reduced at sites lacking rodents.As conditional mutualists,the rodents could possibly act as antagonistic seed predators rather than mutualistic seed dispersers at low and middle elevations,thereby resulting in the asymmetric pattern of rodent and seedling abundance with increasing elevation to affect the community assembly and ecosystem functions on a large spatial scale.

A comprehensive review:Research status and trends of planarianology in China

Planarian is an excellent model for studying several scientific issues,and planarianology has become an active research field in the world.Researchers at home and abroad have conducted a lot of in-depth studies on planarians in various areas.This paper outlined the panorama of planarian research in China and summarized the advances from three aspects of taxonomy,molecular phylogeny and phylogeography,regeneration,tissue homeostasis and immunity as well as toxicology.Furthermore,the current problems and future development direction and tendency of planarian research in China are briefly analyzed and prospected.Importantly,the catalogue of planarians in China is also presented.

Systematic identification and screening of functional long noncoding RNAs during planarian regeneration

Freshwater planarians(Platyhelminthes)are ideal models in regenerative biology because of their whole-body regeneration capability(Salo,2006).They are also popular in neuroscience because they possess anterior cephalic ganglia(brains),which can be restored within a week after head removal(Ross et al.,2017).

Role of ultrasonic oscillation in chemical processes in microreactors:A mesoscale issue

The integration of microreactor and ultrasound represents an emerging area for process intensification and has attracted considerable attention in recent years.One of the most important meso-scientific issues in ultrasound techniques is acoustic cavitation,which plays a vital role in the macroscopic performance of an ultrasonic microreactor.In this review,we first briefly summarize the latest research on acoustic cavitation phenomena in microreactors.The effects of channel configuration,solvent properties,and ultrasound parameters are systematically reviewed.In addition,the role of acoustic cavitation in various chemical processes(e.g.,mixing,absorption,emulsification,and particle synthesis)is presented from a mesoscale perspective,which in turn provides guidance for ultrasound applications.A thorough under-standing of the ultrasound intensification mechanism will contribute to the future development of this promising technology.

Molecular systematics, population genetics and phylogeography on planarians(Platyhelminths: Turbellaria): A brief review of molecular markers

Due to their characteristics, such as powerful regeneration capability, high susceptibility to xenobiotics, wide distribution and weak dispersion ability, planarians are used as ideal test animals in several research fields, and planarianology has become a more and more active subject. This paper reviews the research progress of planarians from the aspects of molecular phylogeny, molecular taxonomy, population genetics and phylogeography, and also summarizes the corresponding molecular markers applied. Moreover, the future direction and tendency in this field is briefly analyzed and prospected.

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.

Photokinesis and Djopsin gene expression analysis during the regeneration of planarian eyes

Planarians provide the ideal model for studying eye development,with their simple eye structure and exceptionally rapid regeneration.Here,we observed the eye morphogenesis,photophobic behavior,spectral sensitivity and expression pattern of Djopsin in the freshwater planarian Dugesia japonica.The results showed that:(i)Djopsin encoding the putative protein belonged to the rhabdomeric opsins group and displayed high conservation during animal evolution;(ii)planarians displayed diverse photophobic response to different visible wavelengths and were more sensitive to light blue(495 nm)and yellow(635 nm);(iii)the morphogenesis and functional recovery of eyes were related to the expression pattern of Djopsin during head regeneration;and(iv)Djopsin gene plays a major role in functional recovery during eye regeneration and visual system maintenance in adult planarians.

Genetic diversity,population structure and demographic history of Dugesia japonica in Taihang Mountains

The freshwater planarian Dugesia japonica has become a model organism in regeneration biology and toxicology due to its powerful regeneration capability and highly chemical sensitivity.Nonetheless,little is known about its evolutionary history and demographics.Taihang Mountains is the natural boundary between the Loess Plateau and the North China Plain,and is considered as one of the important priority areas for biodiversity conservation in China.In order to figure out the genetic diversity,population structure and demographic history of D.japonica in Taihang Mountains,a study based on the mitochondrial COI from 116 individuals sampled across 20 populations has been conducted.The results showed that the 116 COI sequences yielded 32 haplotypes,including 8 shared haplotypes and 24 private ones.The overall haplotype diversity(Hd)and nucleotide diversity(π)were 0.920 and 0.083,respectively.Even though the AMOVA results suggested that the genetic variation among populations was significant(FST=0.480,P<0.01),the phylogeny and haplotype network analysis based on 32 haplotypes revealed no obvious phylogeographic pattern.Furthermore,the significantly positive values of neutrality test(Tajima’s D=2.596,P<0.05;Fu’s Fs=2.769,P<0.01)together with the multimodal arrangement of mismatch distribution indicated that D.japonica in Taihang Mountains would have been undergoing population decline.We hope these findings will arouse conservation and management strategy regarding freshwater planarians and contribute to the biodiversity in the long run.

Integrative taxonomy unveils a new species of Dugesia(Platyhelminthes,Tricladida,Dugesiidae)from the southern portion of the Taihang Mountains in northern China,with the description of its complete mitogenome and an exploratory analysis of mitochondrial gene order as a taxonomic character

A new species of Dugesia(Platyhelminthes,Tricladida,Dugesiidae)from northern China is described on the basis of an integrative approach,involving morphology,karyology,histology,molecular distance,molecular phylogeny,and mitochondrial gene order.Here,we present the complete mitogenome of the new species Du-gesia constrictiva Chen&Dong,sp.nov.This new species is mainly characterized by the presence of the following features:asymmetrical openings of the oviducts;large,cuboidal copulatory bursa;vasa deferentia opening through the ventro-lateral wall of the seminal vesicle;laterally compressed seminal vesicle;ventrally displaced ejaculatory duct,opening at the blunt tip of the penis papilla;long duct intercalated between semi-nal vesicle and diaphragm;chromosome complement diploid,with 16 metacentric chromosomes;mitochondrial gene order as follows:cox1-E-nad6-nad5-S2-D-R-cox3-I-Q-K-atp6-V-nad1-W-cox2-P-nad3-A-nad2-M-H-F-rrnS-L1-Y-G-S1-rrnL-L2-T-atp8-C-N-cob-nad4l-nad4.In triclads,mitochondrial gene order is considerably conserved between freshwater planarians and landflatworms,whereas it is variable between marine planarians and both fresh-water and landflatworms.The secondary structures of tRNAs are all equipped with 4 arms,excepting tRNA S1 and tRNA S2,which lack the D arm and have excessively enlarged loops.Numerous transpositions of tRNA are present between D.constrictiva and its congeners.Mitochondrial gene arrangements may form a new,additional tool for taxonomic studies.The phylogenetic tree based on analysis of the mitochondrial genome basically corroborates current classification of the higher taxa of planarianflatworms.