查看更多>>摘要：The development of efficient perovskite light-emitting diodes(PeLEDs)relies strongly on the fabrication of per-ovskite films with rationally designed structures(grain size,composition,surface,etc.).Therefore,an understand-ing of structure-performance relationships is of vital importance for developing high-performance perovskite de-vices,particularly for devices with in-situ fabricated perovskite nanocrystal films.In this study,we reveal the vertical structure of an in-situ fabricated quasi-two-dimensional perovskite film.By combining time-of-flight sec-ondary ion mass spectrometry,energy dispersive spectroscopy,grazing incidence wide-angle X-ray scattering(GIWAXS),and low-temperature photoluminescence spectra,we illustrate that the resulting in-situ fabricated DPPA2Csn-1Pbn(Br0.3I0.7)3n+1(DPPA+:3,3-diphenylpropylammonium)film has a gradient structure with a very thin layer of ligands on the surface,predominantly small-n domains at the top,and predominantly large-n do-mains at the bottom owing to the solubility difference of the precursors.In addition,GIWAXS measurements show that the domain of n=2 on the top layer has an ordered in-plane alignment.Based on the understanding of the film structure,we developed an in-situ fabrication process with ligand exchange to achieve efficient pure red PeLEDs at 638 nm with an average external quantum efficiency(EQE)of 7.4％.The optimized device had a maximum luminance of 623 cd/m2 with a peak EQE of 9.7％.
查看更多>>摘要：Due to the wide range of potential applications for next-generation multi-functional devices,the flexible self-powered photodetector(PD)with polarity-switchable behavior is essential but very challenging to be realized.Herein,a wearable bidirectional self-powered PD based on detached(Al,Ga)N and(In,Ga)N nanowires has been proposed and demonstrated successfully.Arising from the photo voltage-competing dynamics across(Al,Ga)N and(In,Ga)N nanowire photoelectrodes,such PD can generate the positive(33.3 mA W-1)and negative(-0.019 mA W-1)photo-responsivity under ultraviolet(UV)and visible illumination,respectively,leading to the bidirectional photocurrent behavior.Thanks to the introduction of quasi solid-state hydrogel,the PD can work without the liquid-electrolyte,thus remarkably reducing the volume from about 482 cm3 to only 0.18 cm3.Furthermore,the use of hydrogel is found to enhance response speed in the UV range by reducing the response time for more than 95％,which is mainly attributed to the increased open circuit potential and reduced ion transport distance.As the GaN connecting segment is pretty thin,the piezoelectric charges generated by stress are proposed to have only a limited effect on the photocurrent density.Therefore,both the stable on-off switching characteristics and photocurrent densities can still be achieved after being bent 400 times.With an excellent flexibility,this work creates opportunities for technological applications of bidirectional photocurrent PDs in flexible optoelectronic devices,e.g.,wearable intelligent sensors.
查看更多>>摘要：The Belt and Road Initiative(BRI)is a central policy within China's regional development and foreign trade strategy.Traditional trade has typically depended on economic valuation of resources,while the embedded en-vironmental value is rarely considered.This situation exists in most BRI trade evaluations.To address BRI en-vironmental sustainability issues,we consider the role of pivotal Chinese provinces and their key trade partners(ASEAN countries)as an illustration for the environmental value of resource exchanges.Emergy accounting is used as the valuation tool for a sample period of seventeen years.Key results include:(1)Emergy valuations show sustainability of sample provinces decreased over time;(2)ASEAN countries such as Indonesia,Malaysia,Singapore,Thailand,and Vietnam play significant resource roles for provincial economic systems;(3)Diverse trends in trade between pivotal provinces and ASEAN countries resulted in an unbalanced trade structure from trade.Policy implications are proposed to promote a more globally sustainable and fair trade using BRI as an established trade policy.
查看更多>>摘要：Protein misfolding and aggregation are crucial pathogenic factors for cataracts,which are the leading cause of visual impairment worldwide.α-crystallin,as a small molecular chaperone,is involved in preventing protein misfolding and maintaining lens transparency.The chaperone activity of α-crystallin depends on its oligomeric state.Our previous work identified a natural compound,celastrol,which could regulate the oligomeric state ofαB-crystallin.In this work,based on the UNcle and SEC analysis,we found that celastrol induced αB-crystallin to form large oligomers.Large oligomer formation enhanced the chaperone activity of αB-crystallin and prevented aggregation of the cataract-causing mutant βA3-G91del.The interactions between αB-crystallin and celastrol were detected by the FRET(Fluorescence Resonance Energy Transfer)technique,and verified by molecular docking.At least 9 binding patterns were recognized,and some binding sites covered the groove structure of αB-crystallin.Interestingly,αB-R120G,a cataract-causing mutation located at the groove structure,and celastrol can decrease the aggregates of αB-R120G.Overall,our results suggested celastrol not only promoted the formation of largeαB-crystallin oligomers,which enhanced its chaperone activity,but also bound to the groove structure of itsα-crystallin domain to maintain its structural stability.Celastrol might serve as a chemical and pharmacological chaperone for cataract treatment.
查看更多>>摘要：With the expansion of vaccination programs,the policy of terminating nonpharmaceutical interventions for pre-venting the SARS-CoV-2 pandemic should become more flexible.The current study investigated the clinical and economic outcomes of intervention policies combining nonpharmaceutical interventions and vaccination pro-grams for dealing with the SARS-CoV-2 pandemic.An agent-based transmission model was adopted that describes how a SARS-CoV-2 virus spreads in the populations of China.The model inputs were derived from the literature and expert opinion.The following intervention policies were simulated:no intervention,strict nonpharmaceuti-cal interventions,and nonpharmaceutical interventions for workplace,community,school and home gradually terminated by combining vaccination programs for specified age groups(vaccination age in years:20-60,20-70,20-80,≥ 20,≥ 10 and whole population).Cumulative infections and deaths in one calendar year,costs and quality-adjusted life years(QALYs)were measured.When the vaccination program was taken up in at least the≥ 20 years age group in all populations,nonpharmaceutical interventions for workplace and community settings could be gradually terminated because the cumulative number of infections was＜100 per 100,000 persons.Further ending nonpharmaceutical interventions in school and home settings could not meet the target even when the vaccination program had been taken up in all populations.When cumulative deaths were used as the endpoint,nonpharmaceutical interventions in workplace,community and school settings could be gradually ter-minated.Vaccine efficacy and coverage have substantial impacts.Terminating nonpharmaceutical interventions in workplace settings could produce the lowest cost when vaccination programs are taken up at least in the ≥10 years age group;this method dominates most intervention strategies due to its lower costs and higher QALYs.According to our findings,nonpharmaceutical interventions might be gradually terminated in Chinese settings.
NETL
NSTL
万方数据