Advances in the Application of Perovskite Materials

Nowadays, the soar of photovoltaic performance of perovskite solar cells has set off a fever in the study of metal halide perovskite materials. The excellent optoelectronic properties and defect tolerance feature allow metal halide perovskite to be employed in a wide variety of applications. This article provides a holistic review over the current progress and future prospects of metal halide perovskite materials in representative promising applications, including traditional optoelectronic devices(solar cells, light-emitting diodes, photodetectors, lasers), and cutting-edge technologies in terms of neuromorphic devices(artificial synapses and memristors) and pressure-induced emission. This review highlights the fundamentals, the current progress and the remaining challenges for each application, aiming to provide a comprehensive overview of the development status and a navigation of future research for metal halide perovskite materials and devices.

蓝光钙钛矿发光二极管:机遇与挑战

金属卤化钙钛矿由于具有优异的光电性能(如:高电子/空穴迁移率,高荧光量子产率,高色纯度,以及光色可调性等),成为应用于发光二极管(LED)的理想材料。近年来,钙钛矿LED的发展十分迅速,红光和绿光钙钛矿LED的外量子效率(EQE)均已超过20%。然而,蓝光(尤其是深蓝光)钙钛矿LED的EQE以及稳定性依然相对落后,这严重制约了钙钛矿LED在高性能、广色域显示领域和高显色指数白光照明领域的应用。因此,总结现阶段蓝光钙钛矿LED的发展,并剖析其机遇与挑战,对未来蓝光甚至整个钙钛矿LED领域的发展至关重要。本文将蓝光钙钛矿LED根据光色细分为天蓝光、纯蓝光、深蓝光三大部分进行总结,回顾了三种LED器件的发展历程,并详细阐述了现阶段实现他们的主要手段以及相关的基础原理,最后分析了它们各自的问题并提出了相应的解决思路。

Optimum Seeking of Redundant Actuators for M-RCM 3-UPU Parallel Mechanism

The singularity problem brings troubles to the design and application for the parallel mechanism.Currently,redun-dant actuation is one of the useful methods to solve this singularity problem.However,faced to the numerous joints in a parallel mechanism,how to make a quantitative criterion of seeking the most efficient joints added actuators for letting the mechanism passes through singularity is a necessarily open issue.This paper focuses on a 2R1T 3-UPU(U for universal joint and P for prismatic joint)parallel mechanism(PM)with two rotational and one translational(2R1T)degrees of freedom(DOFs)and the ability of multiple remote centers of motion(M-RCM).The singularity analysis based on the indexes of motion/force transmissibility and constraint shows that this PM has transmission singular-ity,constraint singularity,mixed singularity and limb singularity.To solve these singular problems,the quantifiable redundancy transmission index(RTI)and the redundancy constraint index(RCI)are proposed for optimum seeking of redundant actuators for this PM.Then the appropriate redundant actuators are selected and the working scheme for redundant actuators near the corresponding singular configuration are given to help the PM passes through the singularity.This research proposes a quantitative criterion to optimum seeking of redundant actuators for the parallel mechanism to solve its singularity.

Motion Characteristics Analysis of a Novel Spherical Two-degree-of-freedom Parallel Mechanism

Current research on spherical parallel mechanisms(SPMs)mainly focus on surgical robots,exoskeleton robots,entertainment equipment,and other fields.However,compared with the SPM,the structure types and research contents of the SPM are not abundant enough.In this paper,a novel two-degree-of-freedom(2DOF)SPM with symmetrical structure is proposed and analyzed.First,the models of forward kinematics and inverse kinematics are established based on D-H parameters,and the Jacobian matrix of the mechanism is obtained and verified.Second,the workspace of the mechanism is obtained according to inverse kinematics and link interference conditions.Next,rotational characteristics analysis shows that the end effector can achieve continuous rotation about an axis located in the mid-plane and passing through the rotation center of the mechanism.Moreover,the rotational characteristics of the mechanism are proved,and motion planning is carried out.A numerical example is given to verify the kinematics analysis and motion planning.Finally,some variant mechanisms can be synthesized.This work lays the foundation for the motion control and practical application of this 2DOF SPM.

Configuration Synthesis and Performance Analysis of 9‑Speed Automatic Transmissions

Current research of automatic transmission(AT)mainly focuses on the improvement of driving performance,and configuration innovation is one of the main research directions.However,finding new configurations of ATs is one of the main limitations of configuration innovation.In the present study,epicyclic gear trains(EGTs)are applied to investigate mechanisms of 9-speed ATs.Then four kinematic configurations are proposed for automatic transitions.In order to evaluate the performance of proposed mechanisms,the lever analogy method is applied to conduct kinematic and mechanical analyses.The power flow analysis is conducted,and then transmission efficiencies are calculated based on the torque method.The comparative analysis between the proposed and existing mechanisms is carried out where obtained results show that proposed mechanisms have reasonable performance and can be used in ATs.The prototype of an AT is manufactured and the speed test is conducted,which proves the accuracy of analysis and the feasibility of proposed mechanisms.

Machine learning will revolutionize perovskite solar cells

With the emergence of ChatGPT and its rapid iteration speed,artificial intelligence(AI)has undoubtedly become the driving force behind a new wave of technological revolution.After more than half a century of development,AI has become akin to the steam engine of the Industrial Revolution,propelling humanity into the era of intelligence.The global industrial chain has also recognized that AI technology will spearhead a new wave of industrial transformation and development.Machine learning(ML),driven by data,abstracts real-life problems into mathematical problems and solves them using computers.It is currently the mainstream method for addressing many AI problems.Perovskite solar cells(PSCs)are currently the focus of researchers around the world due to their high efficiency,low cost,and simple manufacturing process.They are considered the most promising third-generation solar cell for commercialization.In 2011,the United States proposed the Materials Genome Initiative(MGI).The main idea is to utilize the“trinity”approach of computing,data,and experiments to transform the conventional“trial and error”model of materials research and development,which relies heavily on experience and experimentation,in order to enhance the quality,speed of discovery,development,production,and application of new materials.Driven by the MGI,research on the combination of ML with great application potential and rapidly developing PSC(ML&PSC)emerged(Figure 1).

A New Well-Balanced Finite Volume CWENO Scheme for Shallow Water Equations over Bottom Topography

In this article,we develop a new well-balanced finite volume central weighted essentially non-oscillatory(CWENO)scheme for one-and two-dimensional shallow water equations over uneven bottom.The well-balanced property is of paramount importance in practical applications,where many studied phenomena can be regarded as small perturbations to the steady state.To achieve the well-balanced property,we construct numerical fluxes by means of a decomposition algorithm based on a novel equilibrium preserving reconstruction procedure and we avoid applying the traditional hydrostatic reconstruction technique accordingly.This decomposition algorithm also helps us realize a simple source term discretization.Both rigorous theoretical analysis and extensive numerical examples all verify that the proposed scheme maintains the well-balanced property exactly.Furthermore,extensive numerical results strongly suggest that the resulting scheme can accurately capture small perturbations to the steady state and keep the genuine high-order accuracy for smooth solutions at the same time.

Phonon lasing enhanced mass sensor with zeptogram resolution under ambient conditions

High-sensitivity mass sensors under ambient conditions are essential in various fields such as biological research,gas sensing and environ-mental monitoring.In the current work,a phonon lasing enhanced mass sensor was proposed based on an optomechanical crystal cav-ity under ambient conditions.The phonon lasing was harnessed to achieve ultra-high resolution since it resulted in an extremely nar-row mechanical linewidth(less than 10 kHz).Masses with different weights were deposited on the cavity,it is predicted that the maxi-mum resolution for mass sensing can be 65±19 zg,which approaches the mass order of a protein and an oligonucleotide.This implies the potential application of the proposed method in the biomedical fields such as oligonucleotide drug delivery area and the Human Proteome Project.

Systematic evaluation of three porcine-derived collagen membranes for guided bone regeneration

Guided bone regeneration is one of the most common surgical treatment modalities performed when an additional alveolar bone is required to stabilize dental implants in partially and fully edentulous patients.The addition of a barrier membrane prevents non-osteogenic tissue invasion into the bone cavity,which is key to the success of guided bone regeneration.Barrier membranes can be broadly classified as non-resorbable or resorbable.In contrast to non-resorbable membranes,resorbable barrier membranes do not require a second surgical procedure for membrane removal.Commercially available resorbable barrier membranes are either synthetically manufactured or derived from xenogeneic collagen.Although collagen barrier membranes have become increasingly popular amongst clinicians,largely due to their superior handling qualities compared to other commercially available barrier membranes,there have been no studies to date that have compared commercially available porcine-derived collagen membranes with respect to surface topography,collagen fibril structure,physical barrier property,and immunogenic composition.This study evaluated three commercially available non-crosslinked porcine-derived collagen membranes(Striate+TM,Bio-Gide®and CreosTM Xenoprotect).Scanning electron microscopy revealed similar collagen fibril distribution on both the rough and smooth sides of the membranes as well as the similar diameters of collagen fibrils.However,D-periodicity of the fibrillar collagen is significantly different among the membranes,with Striate+TM membrane having the closest D-periodicity to native collagen I.This suggests that there is less deformation of collagen during manufacturing process.All collagen membranes showed superior barrier property evidenced by blocking 0.2–16.4µm beads passing through the membranes.To examine the immunogenic agents in these membranes,we examined the membranes for the presence of DNA and alpha-gal by immunohistochemistry.No alpha-gal or DNA was detected in any membranes.However,using a more sensitive detection method(real-time polymerase chain reaction),a relatively strong DNA signal was detected in Bio-Gide®membrane,but not Striate+TM and CreosTM Xenoprotect membranes.Our study concluded that these membranes are similar but not identical,probably due to the different ages and sources of porcine tissues,as well as different manufacturing processes.We recommend further studies to understand the clinical implications of these findings.

Development of Climate and Earth System Models in China: Past Achievements and New CMIP6 Results

The Earth–Climate System Model(ECSM)is an important platform for multi-disciplinary and multi-sphere integration research,and its development is at the frontier of international geosciences,especially in the field of global change.The research and development(R&D)of ECSM in China began in the 1980 s and have achieved great progress.In China,ECSMs are now mainly developed at the Chinese Academy of Sciences,ministries,and universities.Following a brief review of the development history of Chinese ECSMs,this paper summarized the technical characteristics of nine Chinese ECSMs participating in the Coupled Model Intercomparison Project Phase 6 and preliminarily assessed the basic performances of four Chinese models in simulating the global climate and the climate in East Asia.The projected changes of global precipitation and surface air temperature and the associated relationship with the equilibrium climate sensitivity under four shared socioeconomic path scenarios were also discussed.Finally,combined with the international situation,from the perspective of further improvement,eight directions were proposed for the future development of Chinese ECSMs.

Short-term local prediction of wind speed and wind power based on singular spectrum analysis and locality-sensitive hashing

With the growing penetration of wind power in power systems, more accurate prediction of wind speed and wind power is required for real-time scheduling and operation. In this paper, a novel forecast model for shortterm prediction of wind speed and wind power is proposed,which is based on singular spectrum analysis(SSA) and locality-sensitive hashing(LSH). To deal with the impact of high volatility of the original time series, SSA is applied to decompose it into two components: the mean trend,which represents the mean tendency of the original time series, and the fluctuation component, which reveals the stochastic characteristics. Both components are reconstructed in a phase space to obtain mean trend segments and fluctuation component segments. After that, LSH is utilized to select similar segments of the mean trend segments, which are then employed in local forecasting, so that the accuracy and efficiency of prediction can be enhanced. Finally, support vector regression is adopted forprediction, where the training input is the synthesis of the similar mean trend segments and the corresponding fluctuation component segments. Simulation studies are conducted on wind speed and wind power time series from four databases, and the final results demonstrate that the proposed model is more accurate and stable in comparison with other models.

In situ construction of ligand nano-network to integrin αvβ3 for angiogenesis inhibition

Angiogenesis occurs during the process of tumor growth,invasion and metastasis,and is essential for the survival of solid tumors.As an integrin significantly ove rexpressed in human tumor vascular endothelial cells,αvβ3 is a suitable targeting site for anti-angiogenesis of tumor.We designed and prepared a selfassembling peptide(SAP)with the ability to targeting αvβ3 and self-assembly.SAP formed nanoparticles in solution and transformed into nanofibrous network once specifically binding to integrin αvβ3 on the surface of human umbilical vein endothelial cells(HUVECs).The SAP network stably anchored on HUVECs over 24h,which consequently resulted in high-efficient inhibition of vascularization.In vitro anti-angiogenesis experiment displayed that the inhibition rate of tube-formation reached 94.9%.In vivo anti-angiogenesis array based on chick chorioallantoic membrane(CAM)model exhibited that the SAP had an inhibition rate up to 63.1%.These results indicated the outstanding anti-angiogenic ability of SAP,potentially for tumor therapy.

A self-assembling peptide targeting VEGF receptors to inhibit angiogenesis

Vascular endothelial growth factor(VEGF)-vascular endothelial growth factor receptor(VEGFR)pathways are essential in tumor angiogenesis,growth and metastasis.Studies on anti-angiogenic therapy have been mostly focused on the blockage of VEGF-VEGFR pathways.We report an extracellularly transformable peptide-based nanomaterial to develop artificial extracellular matrix(ECM)-like networks for high-efficient blockage of natural VEGF-VEGFR interactions.The transformable peptide-based nanomaterial transforms from nanoparticles into nanofibers upon binding to VEGFR in solution.In addition,the transformable peptide-based nanomate rial forms ECM-like fibrous netwo rks on VEGFR overexpressed cells,inhibiting the VEGF-VEGFR interactions and the subsequent angiogenesis.The tube formation is reduced by nearly 85.1% after treatment.This strategy shows excellent potential for anti-angiogenesis,and inhibition of tumor invasion and metastasis.