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A dynamic influence model of social network hotspot based on grey system

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Science China(Information Sciences) 2015年第12期58卷 63-74页

作者： XIAO YunPeng MA Jing LIU YanBing YAN ZhiXian Chongqing University of Posts and Telecommunications (cqupt) Swiss Federal institute of Technology (EPFL)

The outbreak of hotspot in social network may contain complex dynamic genesis. Using user behavior data from hotspots in social network, we study how different user groups play different roles for a hotspot topic. Firstly, by analyzing users’ behavior records, we mine group situation that promotes the *** major attributions in a hotspot outbreak, such as individual, peer and group triggers, are defined formally according to the view-point of social identity, social interaction, retweet depth and opinion leader. Secondly,for the problem of the uneven and sparse data in each stage of hotspot topic’s life cycle, we propose a dynamic influence model based on grey system to formalize the effect of different groups. Then the process of hotspot evolution driven by distinct crowd is showed dynamically. The experimental result confirms that the model is able not only to qualify users’ influence on a hotspot topic but also to predict effectively an upcoming change in a hotspot topic.

关键词： social network hotspot topic grey system influence model dynamic evolution

First-principles study on persistent luminescence mechanism of LiYGeO_(4):Eu^(3+)

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Journal of Rare Earths 2023年第10期41卷 1519-1524,I0002页

作者： Shihang Zhou Bibo Lou Chong-Geng Ma Min Yin Xinjiang Key Laboratory for Luminescence Minerals and Optical Functional Materials School of Physics and Electronic EngineeringXinjiang Normal UniversityUrumqi830054China CAS Key Laboratory of Strongly-Coupled Quantum Matter Physics and School of Physical SciencesUniversity of Science and Technology of ChinaHefei230026China School of Optoelectronic Engineering&cqupt-bul innovation institute Chongqing University of Posts and TelecommunicationsChongqing400065China

LiYGeO_(4):Eu^(3+)is a red persistent luminescent material with a duration of more than 21 *** its persistent luminescence phenomenon has been fully studied,its detailed mechanism is still the subject of ***,we performed first-principles study on the intrinsic point defects and the charge transfer processes in LiYGeO_(4):Eu^(3+)to reveal the mechanism of persistent *** results show that,under charge transfer excitation,the electron is promoted from the valence band(oxygen ion ligand)to the central Eu^(3+)ion to form Eu^(2+)ion in LiYGeO_(4):Eu^(3+),leaving a hole *** charge transfer excitation can relax quickly to the excited state of the Eu^(3+)ion,which produces the characteristic^(5)D_(0)→^(7)F_(J)(J=0-6)*** Li vacancies(V_(Li))and the antisite defects of Li replacing Y site(Li_(Y))and Y replacing Li site(YLi)are main defects,while O vacancies(V_(O))are less important in concentration due to high formation *** and Liy can serve as hole-type traps,with the trap depths suitable for trapping the holes produced by *** delayed release holes can combine with the Eu^(2+)left behind by the illumination,leading to persistent *** VLi trap is shallower than Li_(Y),and the latter is responsible for the long duration of persistent luminescence.A schematic based on the calculation results is constructed to illustrate the mechanism of persistent luminescence.

关键词： Persistent Iuminescence Eu^(3+) Charge transfer Point defects First-principles Rare earths

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Modelling the luminescence mechanism of defective halide perovskites

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Modelling the luminescence mechanism of defective halide per...

A dynamic influence model of social network hotspot based on grey system

中国稀土学会2020学术年会暨江西(赣州)稀土资源绿色开发与高效利用大会

作者：马崇庚 cqupt-bul innovation institute Chongqing University of Posts and Telecommunications (重庆邮电大学)

Since the 1960s,the theoretical spectroscopy of transition metal and rare earth ions has played an important role for the discovery of novel luminescent ***,there are quite few applications of such a theory to the very hot field of d-and f-elements activated halide perovskites emerging as new materials for photovoltaics and *** this talk,we will show the recent development and vigorous vitality of the theoretical spectroscopy by three typical ***,the near-unity narrow-band green emission in (CHN)MnBrzero-dimensional(0-D) perovskites can be unveiled by a proposed universal regulating strategy based on the Dexter’s energy transfer ***,the calculated electronic structures of rare earth-doped CsPb X (X=F,Cl and Br) shown in Figure 1 can be thought of as a good reference for clarifying the photon-electric upconversion mechanism of CsPbF:Zn/Yb/Er(or Tm) ***,the origin of the green luminescence in CsPbBr 0-D perovskites is revealed by considering the existence of isolated CsPbBr nanoclusters.

关键词： Perovskites Transition metal Rare earth Theoretical spectroscopy

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Science China Chemistry 2015年第12期58卷 59-70页

作者： XIAO YunPeng MA Jing LIU YanBing YAN ZhiXian Chongqing University of Posts and Telecommunications (cqupt) Swiss Federal institute of Technology (EPFL)

The outbreak of hotspot in social network may contain complex dynamic genesis. Using user behavior data from hotspots in social network, we study how different user groups play different roles for a hotspot topic. Firstly, by analyzing users' behavior records, we mine group situation that promotes the *** major attributions in a hotspot outbreak, such as individual, peer and group triggers, are defined formally according to the view-point of social identity, social interaction, retweet depth and opinion leader. Secondly,for the problem of the uneven and sparse data in each stage of hotspot topic's life cycle, we propose a dynamic influence model based on grey system to formalize the effect of different groups. Then the process of hotspot evolution driven by distinct crowd is showed dynamically. The experimental result confirms that the model is able not only to qualify users' influence on a hotspot topic but also to predict effectively an upcoming change in a hotspot topic.

关键词： social network hotspot topic grey system influence model dynamic evolution

Mn^(5+)-activated Ca_(6)Ba(PO_(4))_(4)O near-infrared phosphor and its application in luminescence thermometry

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Light(Science & Applications) 2022年第10期11卷 2463-2475页

作者： Miroslav D.Dramicanin Lkasz Marciniak Sanja Kuzman Wojciech Piotrowski Zoran Ristic Jovana Perisa Ivana Evans Jelena Mitric Vesna Dordevic Nebojsa Romcevic Mikhail G.Brik Chong-Geng Ma School of Optoelectronic Engineering&cqupt-bul innovation institute Chongqing University of Posts and TelecommunicationsChongqing 400065PR China Centre of Excellence for Photoconversion Vinca Institute of Nuclear Sciences-National Institute of the Republic of SerbiaUniversity of BelgradeP.O.Box 522Belgrade 11001Serbia institute of Low Temperature and Structure Research Polish Academy of SciencesOkólna 250-422 WroclawPoland Department of Chemistry Durham UniversityDurham DH13LEUK institute of Physics University of BelgradePregrevica 11811080 BelgradeSerbia institute of Physics University of TartuTartu 50411Estonia Department of Theoretical Physics Jan D?ugosz UniversityCzestochowa PL 42200Poland Academy of Romanian Scientists Ilfov Str.No.3050044 BucharestRomania

The near-infrared luminescence of Ca_(6)Ba(PO_(4))_(4)O∶Mn^(5+)is demonstrated and *** excited into the broad and strong absorption band that spans the 500-1000 nm spectral range,this phosphor provides an ultranarrow(FWHM=5 nm)emission centered at 1140 nm that originates from a spin-forbidden ^(1)E → ^(3)A_(2) transition with a 37.5%internal quantum efficiency and an excited-state lifetime of about 350 μ*** derived the crystal field and Racah parameters and calculated the appropriate Tanabe-Sugano diagram for this *** found that 1E emission quenches due to the thermally-assisted cross-over with the ^(3)T_(2) state and that the relatively high Debye temperature of 783 K of Ca_(6)Ba(PO_(4))_(4)O facilitates efficient *** Ca_(6)Ba(PO_(4))_(4)O also provides efficient yellow emission of the Eu^(2+)dopant,we calculated and explained its electronic band structure,the partial and total density of states,effective Mulliken charges of all ions,elastic constants,Debye temperature,and vibrational ***,we demonstrated the application of phosphor in a luminescence intensity ratio thermometry and obtained a relative sensitivity of 1.92%K^(-1) and a temperature resolution of 0.2 K in the range of physiological temperatures.

关键词： spectra. luminescence excited

Bright and tunable emissive monodisperse CsPbI3@Cs4PbI6 nanocomposites via a precise and controllable dissolution−recrystallization method

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Nano Research 2023年第1期16卷 1586-1594页

作者： Luyu Cao Bomei Liu Lin Huang Zhi Zhou Chong-Geng Ma Jian Zhang Jing Wang Ministry of Education Key Laboratory of Bioinorganic and Synthetic Chemistry State Key Laboratory of Optoelectronic Materials and TechnologiesSchool of ChemistrySun Yat-Sen UniversityGuangzhou 510275China School of Materials Science and Engineering Sun Yat-Sen UniversityGuangzhou 510275China College of Science Hunan Optical Agriculture Engineering Technology Research CenterHunan Agricultural UniversityChangsha 410128China cqupt-bul innovation institute Chongqing University of Posts and TelecommunicationsChongqing 400065China Engineering Research Center of Electronic Information Materials and Devices(Ministry of Education) Guangxi Key Laboratory of Information MaterialsGuangxi Collaborative Innovation Center of Structure and Property for New Energy and MaterialsSchool of Materials Science and EngineeringGuilin University of Electronic TechnologyGuilin 541004China

Nowadays,due to uncontrolled synthesis and lack of more direct and systematic evidences,the photoluminescence origin of“zero-dimensional”Cs4PbI6 remains great controversy and the luminescence cannot be *** we propose a controllable dissolution-recrystallization method to synthesize“emissive”and“non-emissive”Cs4PbI6 nanocrystals(NCs)*** comparing“emissive”and“non-emissive”Cs4PbI6 NCs,it is clearly proved that the visible emission in“emissive”Cs4PbI6 NCs comes from embedded CsPbI3 quantum dots(QDs).It is found for CsPbI3@Cs4PbI6 nanocomposites,methyl acetate(MeAC)and cyclohexane play an important role in dissolution and recrystallization respectively to obtain Cs4PbI6 matrix and CsPbI3 *** from this two-step method,the as-synthesized CsPbI3@Cs4PbI6 nanocomposites with CsPbI3 QDs uniformly distributed in Cs4PbI6 matrix are bright with photoluminescence quantum yield(PLQY)up to 71.4%and exhibit improved stability than CsPbI3 ***,utilizing its formation mechanism,the size of embedded CsPbI3 QDs can be controlled by reasonable designing the“dissolution”process,so that the luminescence of this CsPbI3@Cs4PbI6 nanocomposites can be adjusted in a wide range from green to red(554–630 nm).Our finding not only provides a novel method for synthesizing tunable“emissive”Cs4PbI6 NCs,but also makes clear the photoluminescence origin of“emissive”Cs4PbI6.

关键词： CsPbI3@Cs4PbI6 dissolution-recrystallization nanocomposites tunable emission

High-security-level multi-dimensional optical storage medium:nanostructured glass embedded with LiGa_(5)O_(8):Mn^(2+) with photostimulated luminescence

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Light(Science & Applications) 2020年第1期9卷 1799-1808页

作者： Shisheng Lin Hang Lin Chonggeng Ma Yao Cheng Sizhe Ye Fulin Lin Renfu Li Ju Xu Yuansheng Wang Key Laboratory of Optoelectronic Materials Chemistry and Physics Key Laboratory of Design and Assembly of Functional NanostructuresFujian Institute of Research on the Structure of MatterChinese Academy of SciencesFuzhouFujian 350002China University of Chinese Academy of Sciences Beijing 100049China cqupt-BRU innovation institute Chongqing University of Posts and TelecommunicationsChongqing 400065China Xiamen institute of Rare-earth Materials Haixi InstitutesChinese Academy of SciencesXiamenFujian 361000China

The launch of the big data era puts forward challenges for information preservation technology,both in storage capacity and ***,a brand new optical storage medium,transparent glass ceramic(TGC)embedded with photostimulated LiGa5O8:Mn2+nanocrystals,capable of achieving bit-by-bit optical data write-in and read-out in a photon trapping/detrapping mode,is *** highly ordered nanostructure enables light–matter interaction with high encoding/decoding resolution and low bit error ***,going beyond traditional 2D optical storage,the high transparency of the studied bulk medium makes 3D volumetric optical data storage(ODS)possible,which brings about the merits of expanded storage capacity and improved information *** application confirmed the erasable-rewritable 3D storage of binary data and display items in TGC with intensity/wavelength *** present work highlights a great leap in photostimulated material for ODS application and hopefully stimulates the development of new multi-dimensional ODS media.

关键词： optical glass trapping

Carbon dots embedded in lead-free luminescent metal halide crystals toward single-component white emitters

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Science China Materials 2022年第10期65卷 2802-2808页

作者： Weibin Chen Wei Li Xuejie Zhang Chonggeng Ma Zhiguo Xia Bingfu Lei The Key Laboratory for Biobased Materials and Energy of Ministry of Education College of Materials and EnergySouth China Agricultural UniversityGuangzhou 510642China The State Key Laboratory of Luminescent Materials and Devices Guangdong Provincial Key Laboratory of Fiber Laser Materials and Applied TechniquesSchool of Physics and OptoelectronicsSouth China University of TechnologyGuangzhou 510641China Maoming Branch Guangdong Laboratory for Lingnan Modern AgricultureMaoming 525100China School of Optoelectronic Engineering and cqupt-bul innovation institute Chongqing University of Posts and TelecommunicationsChongqing 400065China

The development of single-component white emitters for white light-emitting diodes(WLEDs)remains ***,a rare earth-free white light-emitting composite is developed by assembling blue-emitting carbon dots(CDs)and yellow-emitting Cs_(2)InCl_(5)·H_(2)O:Sb^(3+)metal halide crystals via a facile liquid-liquid diffusion-assisted crystallization *** encapsulation mechanism is then *** on the ratios of blue/yellow emitters,these luminescent composites exhibit white light emission with tunable cold and warm *** composites also possess prominent ultraviolet resistance,thermal tolerance,and good stability at about 200°*** employing such“CDs in metal halide”composites as a converter,a WLED is successfully fabricated with a high color rendering index of 93.6,benefiting from the assembled blue and yellow broadband *** this strategy,the developed composites show great promise in next-generation WLED lighting.

关键词： carbon dots metal halide high color rendering index single-component white emitters

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内嵌碳点的无铅金属卤化物单晶用于单组分白光发射体（英文）

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Science China Materials 2022年

作者：陈炜彬李唯张学杰马崇庚夏志国雷炳富 The Key Laboratory for Biobased Materials and Energy of Ministry of Education College of Materials and Energy South China Agricultural University The State Key Laboratory of Luminescent Materials and Devices Guangdong Provincial Key Laboratory of Fiber Laser Materials and Applied TechniquesSchool of Physics and Optoelectronics South China University of Technology Maoming Branch Guangdong Laboratory for Lingnan Modern Agriculture School of Optoelectronic Engineering and cqupt-bul innovation institute Chongqing University of Posts and Telecommunications

白光发光二极管（WLED）照明光源的发展对于降低能源消耗具有重要意义. 然而, 常用的基于荧光粉转换技术的WLED器件存在自吸收严重、显色指数低和稀土元素供应风险等多方面的不足. 对此, 本文通过组装蓝光碳点（CDs）和无铅黄光金属卤化...

白光发光二极管（WLED）照明光源的发展对于降低能源消耗具有重要意义. 然而, 常用的基于荧光粉转换技术的WLED器件存在自吸收严重、显色指数低和稀土元素供应风险等多方面的不足. 对此, 本文通过组装蓝光碳点（CDs）和无铅黄光金属卤化物(Cs;InCl;·H;O:Sb;)开发了一种新的单组分白光发射材料. 采用液-液扩散辅助结晶方法本工作成功地将CDs嵌入到Cs;InCl;·H;O:Sb;晶体中, 复合材料呈现出白光发射. 调节CDs和Cs;InCl;·H;O:Sb;的比例可实现冷/暖色调可调使用这种“内嵌CDs的卤化物晶体”复合材料作为转换器, 我们成功制造出单一体系WLED, 其显色指数（CRI）高达93.6, 为下一代室内高品质WLED照明光源提供了一种便捷有效的策略.

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