Exciton dynamics in luminescent carbon nanodots： Electron-hole exchange interaction

The electron-hole exchange interaction significantly influences the optical properties of excitons and radiative decay. However, exciton dynamics in luminescent carbon dots （Cdots） is still not clear. In this study, we have developed a simple and efficient one-step strategy to synthesize luminescent Cdots using the pyrolysis of oleylamine. The sp^2 clusters of a few aromatic rings are responsible for the observed blue photoluminescence. The size of these clusters can be tuned by controlling the reaction time, and the energy gap between the π-π＊ states of the sp^2 domains decreases as the sp^2 cluster size increases. More importantly, the strong electron-hole exchange interaction results in the splitting of the exciton states of the sp^2 clusters into the singlet-bright and triplet-dark states with an energy difference ΔE, which decreases with increasing sp^2 cluster size owing to the reduction of the confinement energy and the suppression of the electron-hole exchange interaction.

Polariton lasing in Mie-resonant perovskite nanocavity

Deeply subwavelength lasers(or nanolasers)are highly demanded for compact on-chip bioimaging and sensing at the nanoscale.One of the main obstacles for the development of single-particle nanolasers with all three dimensions shorter than the emitting wavelength in the visible range is the high lasing thresholds and the resulting overheating.Here we ex-ploit exciton-polariton condensation and mirror-image Mie modes in a cuboid CsPbBr3 nanoparticle to achieve coherent emission at the visible wavelength of around 0.53μm from its ultra-small(≈0.007μm3 or≈λ3/20)semiconductor nanocav-ity.The polaritonic nature of the emission from the nanocavity localized in all three dimensions is proven by direct com-parison with corresponding one-dimensional and two-dimensional waveguiding systems with similar material parameters.Such a deeply subwavelength nanolaser is enabled not only by the high values for exciton binding energy(≈35 meV),re-fractive index(>2.5 at low temperature),and luminescence quantum yield of CsPbBr3,but also by the optimization of po-laritons condensation on the Mie resonances with quality factors improved by the metallic substrate.Moreover,the key parameters for optimal lasing conditions are intermode free spectral range and phonons spectrum in CsPbBr3,which govern polaritons condensation path.Such chemically synthesized colloidal CsPbBr3 nanolasers can be potentially de-posited on arbitrary surfaces,which makes them a versatile tool for integration with various on-chip systems.

转光膜对草莓生长及品质的影响

转光膜是一种可以吸收太阳光中部分紫外光,并将其转化为可为植物光合作用利用的蓝紫光和红橙光的功能性农膜。以草莓品种红颜为试材,研究转光膜对草莓生长及品质等的影响。结果表明,与普通膜相比,转光膜可使棚内日平均温度提高0.39℃,生育期积温增加75.0℃;盛果期,转光膜处理的草莓叶片净光合速率和叶绿素含量显著高于普通膜处理,分别增加了14.3%和14.0%;转光膜处理能够显著促进草莓的早熟和增产,与普通膜相比,转光膜处理的草莓可提前10d成熟,每667m^2增产219.9kg;转光膜对改善果实品质有明显的促进作用,草莓第1茬和第2茬果实的VC含量比普通膜处理分别增加了16.1%、24.4%,可溶性糖含量差异不显著。

Regulating Charge and Exciton Distribution in High-Performance Hybrid White Organic Light-Emitting Diodes with n-Type Interlayer Switch

The interlayer(IL) plays a vital role in hybrid white organic light-emitting diodes(WOLEDs); however,only a negligible amount of attention has been given to n-type ILs. Herein, the n-type IL, for the first time,has been demonstrated to achieve a high efficiency, high color rendering index(CRI), and low voltage trade-off.The device exhibits a maximum total efficiency of 41.5 lm W^(-1), the highest among hybrid WOLEDs with n-type ILs. In addition, high CRIs(80–88) at practical luminances(C1000 cd m^(-2)) have been obtained, satisfying the demand for indoor lighting. Remarkably, a CRI of 88 is the highest among hybrid WOLEDs. Moreover, the device exhibits low voltages, with a turn-on voltage of only 2.5 V([1 cd m^(-2)), which is the lowest among hybrid WOLEDs. The intrinsic working mechanism of the device has also been explored; in particular, the role of n-type ILs in regulating the distribution of charges and excitons has been unveiled. The findings demonstrate that the introduction of n-type ILs is effective in developing high-performance hybrid WOLEDs.

New observations-with older ones reviewed-on mass migrations in millipedes based on a recent outbreak on Hachijojima(Izu Islands) of the polydesmid diplopod(Chamberlinius hualienensis,Wang 1956):Nothing appears to make much sense

Mass aggregations and migrations of millipedes despite numerous attempts to find causes for their occurrences are still an enigma. They have been reported from both southern and northern hemisphere countries, from highlands and lowlands of both tropical and temperate regions and they can involve species belonging to the orders Julida and Spirobolida, Polydesmida and Glomerida. According to the main suggestions put forward in the past, mass occurrences in Diplopoda occur：（1） because of a lack of food and a population increase beyond sustainable levels;（2） for the purpose of reproduction and in order to locate suitable oviposition sites;（3） to find overwintering or aestivation sites;（4） because of habitat disruption and changes in the local environment;（5） as a consequence of weather conditions the year（or winter and spring） before. A recent outbreak（November 2014） of a mass migration of the polydesmid Chamberlinius hualienensis Wang 1956 on the Japanese Izu Island of Hachijojima 300 km to the south of Tokyo gave this author an opportunity to review the existing literature on millipede mass migrations and to carry out additional observations on the phenomenon in the field as well as the laboratory. Hitherto unreported heavy infestations with phoretic deutonymphs of the mite Histiostoma sp. as well as dense populations of internal rhabditid nematodes（Oscheius cf. necromena and an unidentified species of the genus Fictor）, suggest that infestations of this kind could be necromenic and either have been a contributing factor for the mass migration or been a consequence of so manyindividuals occurring together at close proximity. It is concluded that mass migrations and aggregations in millipedes do not have one common cause, but represent phenomena that often are seasonally recurring events and appear identical in their outcome, but which have evolved as responses to different causes in different millipede taxa and therefore need to be examined on a case-to-case basis.

Regeneration of adhesive tail pad scales in the New Zealand gecko (Hoplodactylus maculatus) (Reptilia, Squamata; Lacertilia) can serve as an experimental model to analyze setal formation in lizards generally

During the regeneration of the tail in the arboreal New Zealand gecko （Hoplodactylus maculatus） a new set of tail scales, modified into pads bearing setae 5-20 μm long, is also regenerated. Stages of the formation of these specialized scales from epidermal pegs that invaginate the dermis of the regenerating tail are described on the basis of light and electron microscopic images. Within the pegs a differentiating clear layer interfaces with the spinulae and setae of the Oberh^utchen according to a process similar to that described for the digital pads. A layer of clear cytoplasm surrounds the growing tiny setae and eventually comities around them and their spatular ends, later leaving the new setae free- standing on the epidermal surface. The fresh adhesive pads help the gecko to maintain the prehensile function of its regenerated tail as together with the axial skeleton （made of a cylinder of elastic cartilage） the pads allow the regenerated tail to curl around twigs and small branches just like the original tail. The regeneration of caudal adhesive pads represents an ideal system to study the cellular processes that determine setal formation under normal or experimental manipulation as the progressive phases of the formation of the setae can be sequentially analyzed.

吼嘿

（吼!嘿!吼!嘿!）（吼!）我一直在试寿把它做好（嘿!）我一直过着形单彤只的日手（吼!）而我却一直在这儿酣睡（嘿!）睡在自己的床上（吼!）睡在自己的床上（嘿!）（吼！）

建设持续性高绩效的IT团队

在IT的众多领域,有无数团队扮演着各种重要角色。而如何建设高凝聚力、高绩效和高质量团队,一直是难题。本文围绕可持续高绩效团队的建设,做了精彩分析。

Artificial optical synaptic devices with ultra-low power consumption

A BP/CdS heterostructure-based artificial photonic synapse with an ultra-low power consumption is proposed,presenting great potential in high-performance neuromorphic vision systems.

Research on error compensation method for dual-beam measurement of roll angle based on rhombic prism(Invited Paper)

The fabrication deviation of prisms and the error crosstalk are two major factors that produce serious systematic errors in dual-beam roll measurement based on a rhombic prism, and an error compensation method is put forward in this letter to reduce these systematic errors. The rotation matrix, reflection matrix, and refraction matrix are used to calculate and obtain the mathematical relationship model of the roll angle as well as the fabrication deviation of prism and error crosstalk. The fabrication deviation can be obtained through comparison experiments and using the least square method. In this way, the systematic error of the roll measurement caused by fabrication deviation of prism and error crosstalk can be eliminated theoretically. The experimental results show that the maximum error of the roll angle measurement reduces evidently to 3.5″ from the previous 347.2″ after compensation.

Organic semiconductor heterojunctions: electrode-independent charge injectors for high-performance organic light-emitting diodes

Organic light-emitting diodes(OLEDs)are driven by injected charges from an anode and a cathode.The low and high work function metals are necessary for the effective injection of electrons and holes,respectively.Here,we introduce a fully novel design concept using organic semiconductor heterojunctions(OSHJs)as the charge injectors for achieving highly efficient OLEDs,regardless of the work functions of the electrodes.In contrast to traditional injected charges from the electrodes,the injected charges originate from the OSHJs.The device performance was shown to be significantly improved in efficiency and stability compared to conventional OLEDs.Attractively,the OLEDs based on OSHJs as charge injectors still exhibited an impressive performance when the low work function Al was replaced by air-and chemistry-stable high work function metals,such as Au,Ag,and Cu,as the cathode contact,which has been suggested to be difficult in conventional OLEDs.This concept challenges the conventional design approach for the injection of charges and allows for the realization of practical applications of OLEDs with respect to high efficiency,selectable electrodes,and a long lifetime.

High-efficiency CdTe/CdS core/shell nanocrystals in water enabled by photo-induced colloidal hetero-epitaxy of CdS shelling at room temperature

We report high-efficiency CdTe/CdS core/shell nanocrystals synthesized in water by epitaxially growing CdS shells on aqueous CdTe cores at room temperature, enabled by the controlled release of S species under low-intensity ultraviolet （UV） light illumination. The resulting photo-induced dissociation of S2O2- ions conveniently triggers the formation of critical two-dimensional CdS epitaxy on the CdTe surface at room temperature, as opposed to initiating the growth of individual CdS core-only nanocrystals. This controlled colloidal hetero-epitaxy leads to a substantial increase in the photoluminescence （PL） quantum yield （QY） of the shelled nanocrystals in water （reaching 64%）. With a systematic set of studies, the maximum PL QY is found to be almost independent of the illuminating UV intensity, while the shell formation kinetics required for reaching the maximum QY linearly depends on the illuminating UV intensity. A stability study of the QD films in air at various temperatures shows highly improved thermal stability of the shelled QDs （up to 120 ℃ in ambient air）. These results indicate that the proposed aqueous CdTe/CdS core/shell nanocrystals hold great promise for applications requiring efficiency and stability.

Interfacial charge and energy transfer in van der Waals heterojunctions

Van der Waals heterojunctions are fast-emerging quantum structures fabricated by the controlled stacking of two-dimensional(2D)materials.Owing to the atomically thin thickness,their carrier properties are not only determined by the host material itself,but also defined by the interlayer interactions,including dielectric environment,charge trapping centers,and stacking angles.The abundant constituents without the limitation of lattice constant matching enable fascinating electrical,optical,and magnetic properties in van der Waals heterojunctions toward next-generation devices in photonics,optoelectronics,and information sciences.This review focuses on the charge and energy transfer processes and their dynamics in transition metal dichalcogenides(TMDCs),a family of quantum materials with strong excitonic effects and unique valley properties,and other related 2D materials such as graphene and hexagonalboron nitride.In the first part,we summarize the ultrafast charge transfer processes in van der Waals heterojunctions,including its experimental evidence and theoretical understanding,the interlayer excitons at the TMDC interfaces,and the hot carrier injection at the graphene/TMDCs interface.In the second part,the energy transfer,including both Förster and Dexter types,are reviewed from both experimental and theoretical perspectives.Finally,we highlight the typical charge and energy transfer applications in photodetectors and summarize the challenges and opportunities for future development in this field.

Focus on using nanopore technology for societal health,environmental,and energy challenges

With an increasing global population that is rapidly ageing,our society faces challenges that impact health,environment,and energy demand.With this ageing comes an accumulation of cellular changes that lead to the development of diseases and susceptibility to infections.This impacts not only the health system,but also the global economy.As the population increases,so does the demand for energy and the emission of pollutants,leading to a progressive degradation of our environment.This in turn impacts health through reduced access to arable land,clean water,and breathable air.New monitoring approaches to assist in environmental control and minimize the impact on health are urgently needed,leading to the development of new sensor technologies that are highly sensitive,rapid,and low-cost.Nanopore sensing is a new technology that helps to meet this purpose,with the potential to provide rapid point-of-care medical diagnosis,real-time on-site pollutant monitoring systems to manage environmental health,as well as integrated sensors to increase the efficiency and storage capacity of renewable energy sources.In this review we discuss how the powerful approach of nanopore based single-molecule,or particle,electrical promises to overcome existing and emerging societal challenges,providing new opportunities and tools for personalized medicine,localized environmental monitoring,and improved energy production and storage systems.

Small Form Factor Fiber Optic Transceiver Module for High-end SONET/SDH Application

Introduction Due to the trend towards higher port densities in high-capacity communication systems, Small Form Factor (SFF) Transceivers are becomingpopular. Originally, SFF transceivers were designed to address short reach (2km) and intermediate reach (15km) applications using PIN receivers. We have developed SFF transceivers for the high-end SONET/SDH space (2.5Gb/s speed for 40km and 80km reach). This part of the SONET/SDH space is unique due to the need for Avalanche Photo Diode (APD) based receiver...

探寻当代东方珠宝的样貌

从1880年起,西方世界的新艺术、装饰艺术、流线风格与极简主义,几乎定义了当代珠宝的样貌,一百多年过去,亚洲市场崛起,3D设计与制作工法突飞猛进,珠宝业迎来前所未有的巨变,身处东方世界的珠宝产业工作者,我们是否也能有机会去定义当代珠宝的样貌呢?

All-optical control of exciton flow in a colloidal quantum well complex

Excitonics,an alternative to romising for processing information since semiconductor electronics is rapidly approaching the end of Moore’s law.Currently,the development of excitonic devices,where exciton flow is controlled,is mainly focused on electric-field modulation or exciton polaritons in high-Q cavities.Here,we show an alloptical strategy to manipulate the exciton flow in a binary colloidal quantum well complex through mediation of the Förster resonance energy transfer(FRET)by stimulated emission.In the spontaneous emission regime,FRET naturally occurs between a donor and an acceptor.In contrast,upon stronger excitation,the ultrafast consumption of excitons by stimulated emission effectively engineers the excitonic flow from the donors to the acceptors.Specifically,the acceptors’stimulated emission significantly accelerates the exciton flow,while the donors’stimulated emission almost stops this process.On this basis,a FRET-coupled rate equation model is derived to understand the controllable exciton flow using the density of the excited donors and the unexcited acceptors.The results will provide an effective alloptical route for realizing excitonic devices under room temperature operation.

Mechanosynthesis of polymer-stabilized lead bromide perovskites:Insight into the formation and phase conversion of nanoparticles

The application of polymers to replace oleylamine(OLA)and oleic acid(OA)as ligands for perovskite nanocrystals is an effective strategy to improve their stability and durability especially for the solution-based processing.Herein,we report a mechanosynthesis of lead bromide perovskite nanoparticles(NPs)stabilized by partially hydrolyzed poly(methyl methacrylate)(h-PMMA)and highmolecular-weight highly-branched poly(ethylenimine)(PEI-25K).The as-synthesized NP solutions exhibited green emission centered at 516 nm,possessing a narrow full-width at half-maximum of 17 nm and as high photoluminescence quantum yield(PL QY)as 85%,while showing excellent durability and resistance to polar solvents,e.g.,methanol.The colloids of polymer-stabilized NPs were directly processable toform stable and strongly-emitting thin films and solids,making them attractive as gain media.Furthermore,the roles of h-PMMA and PEI-25K in the grinding process were studied in depth.The h-PMMA can form micelles in the grinding solvent of dichloromethane to act as size-regulating templates for the growth of NPs.The PEI-25K with large amounts of amino groups induced significant enrichment of PbBr_(2)in the reaction mixture,which in turn caused the formation of CsPb_(2)Br_(5)-mPbBr_(2)and CsPbBr_(3)-Cs_(4)PbBr_(6)-nCsBr NPs.The presence of CsPbBr_(3)-Cs_(4)PbBr_(6)-nCsBr NPs was responsible for the high PL QY,as the Cs_(4)PbBr_(6)phase with a wide energy bandgap can passivate the surface defects of the CsPbBr_(3)phase.This work describes a direct and facile mechanosynthesis of polymer-coordinated perovskite NPs and promotes in-depth understanding of the formation and phase conversion for perovskite NPs in the grinding process.