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One-pot/three-step synthesis of zinc-blende CdSe/CdS core/shell nanocrystals with thick shells

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Nano Research 2017年第4期10卷 1149-1162页

作者： Yuan Niu Chaodan Pu runchen lai Renyang Meng Wanzhen Lin Haiyan Qin Xiaogang Peng Center for Chemistry of Novel and High-Performance Materials and Department of Chemistry Zhejiang University Hangzhou 310027 China

A one-pot/three-step synthetic scheme was developed for phase-pure epitaxy of CdS shells on zinc-blende CdSe nanocrystals to yield shells with up to sixteen monolayers. The key parameters for the epitaxy were identified, including the core nanocrystal concentration, solvent type/composition, quality of the core nanocrystals, epitaxial growth temperature, type/concentration of ligands, and composition of the precursors. Most of these key parameters were not influential when the synthetic goal was thin-shell CdSe/CdS core/shell nanocrystals. The finalized synthetic scheme was reproducible at an almost quantitative level in terms of the crystal structure, shell thickness, and optical properties.

关键词： zinc-blende core/shell quantum dots thick shells

Highly reactive, flexible yet green Se precursor for metal selenide nanocrystals： Se-octadecene suspension （Se-SUS）

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Nano Research 2013年第9期6卷 652-670页

作者： Chaodan Pu Jianhai Zhou runchen lai Yuan Niu Wennuan Nan Xiaogang Peng Center for Chemistry of Novel & High-Performance Materials and Department of Chemistry Zhejiang University Hangzhou 310027 China

A suspension of fine selenium （Se） powder （100 or 200 mesh） in octadecene （Se-SUS） has proven to be a high-performance, versatile, convenient, reproducible, yet green Se precursor. The advantages of Se-SUS arise from its highly reactive chemical nature and flexibility. These two features made it possible to carry out the synthesis of high quality metal selenide nanocrystals with diverse compositions and structures, including binary, core/shelL transition metal doped, and complex composition nanocrystals. These successes further demonstrated that Se-SUS is a powerful Se precursor for solving a few long- standing challenges in the synthesis of high quality selenide nanocrystals. For instance, Se-SUS was successfully employed as a Se precursor for shell growth in high quality core/shell nanocrystals to replace expensive and highly toxic precursors, such as Se-phosphine and bis-trimethylsilyl selenide, with greatly lowered epitaxial temperatures （as low as 150℃） to avoid alloying. As another example, Se-SUS enabled ＂co-nucleation doping＂ as a means of preparing high quality Mn doped ZnSe nanocrystals with pure, stable, and highly efficient dopant fluorescence.

关键词： selenium precursor selenium suspension metal selenide nanocrystals

Additive and interfacial control for efficient perovskite light-emitting diodes with reduced trap densities

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Journal of Semiconductors 2022年第5期43卷 32-44页

作者： Shun Tian Chen Zou runchen lai Chungen Hsu Xuhui Cao Shiyu Xing Baodan Zhao Dawei Di State Key Laboratory of Modern Optical Instrumentation College of Optical Science and EngineeringInternational Research Center for Advanced PhotonicsZhejiang UniversityHangzhou 310027China

Metal halide perovskite semiconductors show excellent optoelectronic properties including tunable bandgaps[1,2],narrow emission bandwidths[3]and high luminescence quantum efficiencies[4],making them an ideal candidate for light-emitting diode(LED)*** LEDs(PeLEDs)have attracted considerable attention since the initial report of room-temperature electroluminescence(EL)from halide perovskites in 2014[5].

关键词： diodes optoelectronic light

Power Flow Analytical Solutions and Multi-dimensional Voltage Stability Boundaries Based on Multivariate Quotient-difference Method

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CSEE Journal of Power and Energy Systems 2024年第3期10卷 1168-1178页

作者： Chengxi Liu Qiupin lai School of Electrical Engineering and Automation Wuhan UniversityWuhan 430072China Hubei Engineering and Technology Research Center for AC/DC Intelligent Distribution Network Wuhan 430072China IEEE

This paper proposes a novel Multivariate Quotient-Difference(MQD)method to obtain the approximate analytical solution for AC power flow ***,in the online environment,the power flow solutions covering different operating conditions can be directly obtained by plugging values into multiple symbolic variables,such that the power injections and consumptions of selected buses or areas can be independently *** method first derives a power flow solution through a Multivariate Power Series(MPS).Next,the MQD method is applied to transform the obtained MPS to a Multivariate Pad´e Approximants(MPA)to expand the Radius of Convergence(ROC),so that the accuracy of the derived analytical solution can be significantly *** addition,the hypersurface of the voltage stability boundary can be identified by an analytical formula obtained from the coefficients of *** direct method for power flow solutions and voltage stability boundaries is fast for many online applications,since such analytical solutions can be derived offline and evaluated online by only plugging values into the symbolic variables according to the actual operating *** proposed method is validated in detail on New England 39-bus and IEEE 118-bus systems with independent load variations in multi-regions.

关键词： Analytical power flow solution multivariate power series multivariate Padéapproximants multivariate quotient-difference multi-dimensional voltage stability boundary

Preface to the Special Issue:Additive Manufacturing—Expanding Production Horizon

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Acta Metallurgica Sinica(English Letters) 2024年第1期37卷 1-2页

作者： lai-Chang Zhang Centre for Advanced Materials and Manufacturing School of EngineeringEdith Cowan University270 Joondalup DriveJoondalupPerthWA6027Australia

Additive manufacturing(AM),commonly known as 3D printing,has become a transformative technology that has a profound impact on various industrial *** encompasses a set of techniques for building objects layer by layer from digital *** conventional subtractive manufacturing methods that involve removing material from large blocks,AM adds material incrementally,providing unprecedented design flexibility and efficiency.

关键词： removing printing Expanding

Macroscopic assembled graphene nanofilms based room temperature ultrafast mid-infrared photodetectors

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InfoMat 2022年第6期4卷 129-140页

作者： Li Peng Lixiang Liu Sichao Du Srikrishna Chanakya Bodepudi Lingfei Li Wei Liu runchen lai Xiaoxue Cao Wenzhang Fang Yingjun Liu Xinyu Liu Jianhang Lv Muhammad Abid Junxue Liu Shengye Jin Kaifeng Wu Miao-Ling Lin Xin Cong Ping-Heng Tan Haiming Zhu Qihua Xiong Xiaomu Wang Weida Hu Xiangfeng Duan Bin Yu Zhen Xu Yang Xu Chao Gao MOE Key Laboratory of Macromolecular Synthesis and Functionalization Department of Polymer Science and EngineeringInternational Research Center for X PolymersZhejiang UniversityHangzhouChina School of Micro-nanoelectronics State Key Laboratory of Silicon MaterialsHangzhou Global Scientific and Technological Innovation CenterZJU-UIUC Joint InstituteZhejiang UniversityHangzhouChina State Key Laboratory of Molecular Reaction Dynamics and Dynamics Dalian Institute of Chemical PhysicsChinese Academy of SciencesDalianChina State Key Laboratory of Superlattices and Microstructures Institute of SemiconductorsChinese Academy of SciencesBeijingChina Department of Chemistry Zhejiang UniversityHangzhouChina Division of Physics and Applied Physics School of Physical and Mathematical SciencesNanyang Technological UniversitySingaporeSingapore National Laboratory of Solid State Microstructures Collaborative Innovation Center of Advanced MicrostructureSchool of Electronic Science and EngineeringNanjing UniversityNanjingChina State Key Laboratory of Infrared Physics Shanghai Institute of Technical PhysicsChinese Academy of SciencesShanghaiChina Department of Chemistry and Biochemistry California Nanosystems InstituteUniversity of CaliforniaLos AngelesCaliforniaUSA

Graphene with linear energy dispersion and weak electron-phonon interaction is highly anticipated to harvest hot electrons in a broad wavelength ***,the limited absorption and serious backscattering of hot-electrons result in inadequate quantum yields,especially in the mid-infrared ***,we report a macroscopic assembled graphene(nMAG)nanofilm/silicon heterojunction for ultrafast mid-infrared *** assembled Schottky diode works in 1.5-4.0μm at room temperature with fast response(20-30 ns,rising time,4 mm2 window)and high detectivity(1.61011 to 1.9109 Jones from 1.5 to 4.0μm)under the pulsed laser,outperforming single-layer-graphene/silicon photodetectors by 2-8 *** performances are attributed to the greatly enhanced photo-thermionic effect of electrons in nMAG due to its high light absorption(~40%),long carrier relaxation time(~20 ps),low work function(4.52 eV),and suppressed carrier number *** nMAG provides a long-range platform to understand the hot-carrier dynamics in bulk 2D materials,leading to broadband and ultrafast MIR active imaging devices at room temperature.

关键词： graphene nanofilm heterojunction macro-assembly mid-infrared photodetector photothermionic effect

Remote sensing image encryption algorithm utilizing 2D Logistic memristive hyperchaotic map and SHA-512

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Science China(Technological Sciences) 2024年第5期67卷 1553-1566页

作者： lai Qiang LIU Yuan YANG Liang School of Electrical and Automation Engineering East China Jiaotong UniversityNanchang330013China

The two-dimensional Logistic memristive hyperchaotic map(2D-LMHM)and the secure hash SHA-512 are the foundations of the unique remote sensing image encryption algorithm(RS-IEA)suggested in this *** proposed map is formed from the improved Logistic map and the memristor,which has wide phase space and hyperchaotic range and is exceptionally excellent to be utilized in specific *** proposed image algorithm uses the permutation-assignment-diffusion *** generates two position matrices in a progressive manner to achieve an efficient random exchange of pixel positions,assignment is carried through on the image pixels of the permutated image to entirely remove the original image information,strengthening the relationship between permutation and diffusion,and loop diffusion in two different directions can use subtle changes of pixels to affect the whole *** random key and plain-image SHA-512 hash values are used to produce an additional key,which is then utilized to figure out the permutation parameters and the initial value of a chaotic *** experimental results with the average NPCR=99.6094%(NPCR:number of pixels change rate),average UACI=33.4638%(UACI:unified average changing intensity),100%pass rate of the targets in the test set,the average correlation coefficient is 0.00075,and the local information entropy is 7.9025,which shows that the algorithm is able to defend against a variety of illegal attacks and provide more trustworthy protection than some of the existing state-of-the-art algorithms.

关键词： chaos memristive hyperchaotic map remote sensing SHA-512 image encryption RS-IEA

Supercoiled DNA Minicircles under Double-strand Breaks

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Chinese Journal of Polymer Science 2024年第9期42卷 1353-1359,I0007页

作者： Ye-Peng Qiao Chun-lai Ren National Laboratory of Solid State Microstructures and Department of Physics Collaborative Innovation Center of Advanced MicrostructuresNanjing UniversityNanjing210093China

Understanding how supercoiled DNA releases intramolecular stress is essential for its functional ***,the molecular mechanism underlying the relaxation process remains insufficiently *** we employed MD simulations based on the oxDNA2 model to investigate the relaxation process of a 336-base pair supercoiled minicircular DNA under double-strand breaks with two fixed *** simulations show that the conformational changes in the DNA occur continuously,with intramolecular stress release happening abruptly only when the DNA chain traverses the breakage *** relaxation process is influenced not only by the separation distance between the fixed ends but also their ***,we observe an inhibitory effect on the relaxation characterized by small angles,where short terminal loops impede DNA conformational adjustments,preserving the supercoiled *** findings elucidate the intricate interplay between DNA conformational change,DNA motion and intramolecular stress release,shedding light on the mechanisms governing the relaxation of supercoiled DNA at the molecular level.

关键词： Supercoiled DNA DNA minicircle DNA relaxation oxDNA model MD simulation

First Digit Distributions of Gamma-Ray Bursts

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Research in Astronomy and Astrophysics 2024年第5期24卷 70-75页

作者： Hou-Yu lai Jun-Jie Wei Purple Mountain Observatory Chinese Academy of SciencesNanjing 210023China School of Astronomy and Space Sciences University of Science and Technology of ChinaHefei 230026China

The occurrence of the first significant digits from real world sources is usually not equally distributed,but is consistent with a logarithmic distribution instead,known as Benford’s *** this work,we perform a comprehensive investigation on the first digit distributions of the duration,fluence,and energy flux of gamma-ray bursts (GRBs) for the first *** a complete GRB sample detected by the Fermi satellite,we find that the first digits of the duration and fluence adhere to Benford’s ***,the energy flux shows a significant departure from this law,which may be due to the fact that a considerable part of the energy flux measurements is restricted by lack of spectral *** on the conventional duration classification scheme,we also check if the durations and fluences of long and short GRBs (with duration T_(90)>2 s and T_(90)≤2 s,respectively) obey Benford’s *** find that the fluences of both long and short GRBs still agree with the Benford distribution,but their durations do not follow Benford’s *** results hint that the long–short GRB classification scheme does not directly represent the intrinsic physical classification scheme.

关键词： (stars:)gamma-ray burst general-methods statistical-astronomical databases miscellaneous