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Improving luminescence and thermometric performance of Ba_(2)CaWO_(6):Er^(3+) by tri-doping with Yb^(3+) and Na^(+)

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Journal of Rare Earths 2023年第1期41卷 42-50页

作者： lingyun li Ziwei Zhou Fazheng Huang Senlin Peng Yantang Huang Guoqiang Wang xinxu li Fei-Fei Chen Chengkai Yang xin-xiong li Yan Yu Key Laboratory of Advanced Materials Technology College of Materials Science and EngineeringFuzhou UniversityFuzhou 350108China College of Chemistry Fuzhou UniversityFuzhou 350108China College of Physics and Information Engineering Fuzhou UniversityFuzhou 350108China

The Er3+doped double perovskite Ba_(2)CaWO_(6) crystal is a promising ratiometric thermometer based on the fluorescence intensity ratio(FIR) of transitions from ^(2)H_(11/2) and ^(4)S_(3/2) to the lowered ^(4)I_(15/2) ***,the Ca^(2+) vacancy defect caused by the charge difference between rare-earth ions and the substituted alkaline-earth ions gives rise to the non-radiative probability and limits the thermal ***,the up-conversion luminescence and thermometric performance of Er^(3+),Yb^(3+) dopedBa_(2)CaWO_(6) are tuned by tri-doping with alkaline *** Ca^(2+) vacancy defect can be eliminated by the introduction of Na^(+),which occupies the Ca^(2+) site when it is doped into Ba_(2)CaWO_(6) with Er^(3+) and Yb^(3+).On the contrary,the doping of Cs^(+) into Ba_(2)CaWO_(6) with Er^(3+) and Yb^(3+) enhances the defect concentration because it occupies the site of Ba^(2+).Thus,the tri-doping of Na^(+) reduces the non-radiative probability and enhances the quantum efficiency of Er^(3+),leading to the improvement of the thermometric sensitivity of Ba_(2)CaWO_(6).As a result,we get an excellent thermometric Ba_(2)CaWO_(6):8%Yb^(3+),3.5%Er^(3+),6%Na^(+) powder with a luminescence lifetime of 515 μs and maximum thermal sensitivity(S_(r)) of 1.45%/K,which is more than three times higher than that of the BCWO:Er^(3+) powder.

关键词： Up-conversion luminescence Optical thermometry Ba_(2)CaWO_(6) Er^(3+) Double perovskite Rare earths

A rare porous zinc phosphonocarboxylate framework with high thermal stability and interesting structural transformation

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Chinese Chemical Letters 2018年第6期29卷 959-962页

作者： Yan-Jie Qi Jin-Hua liu Wen-Xu Zheng xin-xiong li Shou-Tian Zheng State Key Laboratory of Photocatalysis on Energy and Environment College of Chemistry Fuzhou University

A rare porous zinc-organic framework with ultrahigh thermal stability over 500℃ was obtained, which exhibits a CaF2-type topology formed by 8-connected tetranuclear Zn4 clusters and 4-connected phosphonocarboxylate ligands. Interestingly, the similar reactions to the 2 zinc-organic framework but in the absence of H2 O or by the replacement of Zn2＋with Co2＋can yield three different 3 D cluster-based frameworks but with the same CaF2-type topology.

关键词： Phosphonocarboxylate ligand Metal-organic framework Stability Structural transformation Gas adsorption

Orbit and clock products for quad-system satellites with undifferenced ambiguity fixing approach

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Satellite Navigation 2024年第1期5卷 125-139页

作者： Jiaqi Wu xingxing li Yongqiang Yuan Keke Zhang xin li Jiaqing Lou Yun xiong School of Geodesy and Geomatics Wuhan University129 Luoyu RoadWuhan430079China Hubei Luojia Laboratory 129 Luoyu RoadWuhan430079China German Research Centre for Geosciences GFZ Telegrafenberg14473PotsdamGermany Technische Universitat Berlin(TUB) Straße Des 17.Juni10623BerlinGermany

Integer Ambiguity Resolution(IAR)can significantly improve the accuracy of GNSS Precise Orbit Determination(POD).Traditionally,the IAR in POD is achieved at the Double Differenced(DD)*** this contribution,we develop an Un-Differenced(UD)IAR method for Global Positioning System(GPS)+BeiDou Navigation Satellite System(BDS)+Galileo navigation satellite system(Galileo)+Global'naya Navigatsionnaya Sputnikovaya Sistema(GLONASS)quad-system POD by calibrating UD ambiguities in the raw carrier phase and generating the so-called carrier *** on this method,we generate the UD ambiguity-fixed orbit and clock products for the Wuhan Innovation Application Center(IAC)of the International GNSS Monitoring and Assessment System(iGMAS).One-year observations in 2020 from 150 stations are employed to investigate performance of orbit and clock ***,the UD Ambiguity Resolution(AR)yields more resolved integer ambiguities than the traditional DD AR,scaling up to 9%,attributable to its avoidance of station baseline *** from the removal of ambiguity parameters,the computational efficiency of parameter estimation undergoes a substantial 70%*** with the float solution,the orbit consistencies of UD AR solution achieve the accuracy of 1.9,5.2,2.8,2.1,and 2.7 cm for GPS,BeiDou-2 Navigation Satellite System(BDS-2),BeiDou-3 Navigation Satellite System(BDS-3),Galileo,and GLONASS satellites respectively,reflecting enhancements of 40%,24%,54%,34%,and 42%.Moreover,the standard deviations of Satellite Laser Ranging(SLR)residuals are spanning 2.5–3.5 cm,underscoring a comparable accuracy to the DD AR solution,with discrepancies below 5%.A notable advantage of UD AR lies in its capability to produce the Integer Recovered Clock(IRC),facilitating Precise Point Positioning(PPP)AR without requiring additional Uncalibrated Phase Delay(UPD)*** assess the performance of quad-system kinematic PPP based on IRC,a network comprising 120 stations is uti

关键词： Multi-GNSS Precise orbit determination Integer recover clock Undifferenced ambiguity resolution iGMAS innovation application center

Effect of tungsten carbide particles on microstructure and mechanical properties of Cu alloy composite bit matrix

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Journal of Iron and Steel Research International 2024年第2期31卷 519-530页

作者： Ding-qian Dong Feng-yuan He xin-hui Chen Hui li Kai-hua Shi Hui-wen xiong xin Xiang li Zhang College of Mechanical Engineering Sichuan University of Science and EngineeringZigong643000SichuanChina State Key Laboratory of Powder Metallurgy Central South UniversityChangsha410083HunanChina Zigong Cemented Carbide Co. Ltd.Zigong643011SichuanChina Material Corrosion and Protection Key Laboratory of Sichuan Province Sichuan University of Science and EngineeringZigong643000SichuanChina

Copper alloy composite bit matrix was prepared by pressureless vacuum infiltration,using at least one of the three kinds of tungsten carbide particles,for example,irregular cast tungsten carbide,monocrystalline tungsten carbide and sintered reduced tungsten carbide *** effects of powder particle morphology,particle size and mass fraction of tungsten carbide on the microstructure and mechanical properties of copper alloy composite were investigated by means of scanning electron microscopy,X-ray diffraction and abrasive wear test in *** results show that tungsten carbide morphology and particle size have obvious effects on the mechanical properties of copper alloy *** tungsten carbide partially dissolved in the copper alloy binding phase,and layers of Cu_(0.3)W_(0.5)Ni_(0.1)Mn_(0.1)C phase with a thickness of around 8–15μm were formed on the edge of the cast tungsten *** 45%irregular crushed fine cast tungsten carbide and 15%monocrystalline cast tungsten carbide were used as the skeleton,satisfactory comprehensive performance of the reinforced copper alloy composite bit matrix was obtained,with the bending strength,impact toughness and hardness reaching 1048 MPa,4.95 J/cm^(2) and 43.6 HRC,*** main wear mechanism was that the tungsten carbide particles firstly protruded from the friction surface after the copper alloy matrix was worn,and then peeled off from the matrix when further wear occurred.

关键词： Polycrystalline diamond compact Pressureless vacuum infiltration Copper alloy composite bit matrix Microstructure characterization Abrasive wear behavior

Geomorphology-oriented theoretical framework and construction method for value-added DEM

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Journal of Geographical Sciences 2024年第1期34卷 165-184页

作者： ZHANG Haiping TANG Guoan xiong liyang YANG xin li Fayuan Key Laboratory of Virtual Geographic Environment Ministry of EducationNanjing Normal UniversityNanjing 210023China School of Geography Nanjing Normal UniversityNanjing 210023China Jiangsu Center for Collaborative Innovation in Geographical Information Resource Development and Application Nanjing 210023China

Digital elevation model(DEM)plays a fundamental role in the study of the earth system by expressing surface configuration,understanding surface process,and revealing surface *** is widely used in analysis and modeling in the field of ***,traditional DEM has the defect of single attribute,which is difficult to support the research in earth system science oriented to geoscience process and mechanism ***,realizing the value-added data model on the basis of traditional DEM is necessary to serve digital elevation modeling and terrain analysis under the background of a new geomorphology research paradigm and earth observation technology.A theoretical framework for value-added DEM that mainly includes concept,connotation,content,and categories,is constructed in this *** relationship between different types of value-added DEMs as well as the research significance and application category of this theoretical framework are also *** following are different methods of value-added DEMs:(1)value-added methods of DEM space and time dimensions that emphasize the integration of the ground and underground as well as coupling of time and space,(2)attribute-based value-added methods composed of material(including underground,surface,and ground)and morphological properties,and(3)value-added methods of features and physical elements that consider geographical objects and landform features formed by natural processes and artificial *** digital terrace,slope,and watershed models are used as examples to illustrate application scenarios of the three kinds of value-added *** study aims to improve expression methods of DEMs under the background of new surveying and mapping technologies by adding value to the DEM at three levels of dimensions,attributes,and elements as well as support knowledge-driven digital geomorphological analysis in the era of big data.

关键词： spatial data model value-added DEM digital terrain analysis geomorphological ontology geomorphology

A series of high-nuclear planar equilateral triangle-shaped {Ln_(6)(μ_(3)-OH)_(6)} cluster encapsulated polyoxoniobates with frequency dependent magnetic property

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Chinese Chemical Letters 2023年第7期34卷 360-363页

作者： Zeng-Kui Zhu Ya-Yun lin Rong-Da Lai xin-xiong li Yan-Qiong Sun Shou-Tian Zheng State Key Laboratory of Photocatalysis on Energy and Environment College of ChemistryFuzhou UniversityFuzhou 350108China

The integration of lanthanide(Ln)ions and polyoxoniobates(PONbs)is challenging,and the know Ln-substituted PONbs are still *** work introduces high-nuclear iso-Ln-oxo clusters into th PONb *** first series of high-nuclear Ln-oxo clusters encapsulated heterometallic polyoxonio bates H_9[Na(H_(2)O)_(4)][Cu(en)_(2)]_(10){Ln_6(μ_(3)-OH)_6(Si Nb_(18)O_(54))_(3)}·18H_(2)O(1-Ln,en=ethylenediamine,Ln=Dy,Gd Tb,Ho,Er,Tm,Yb,Lu)based on flower-like{Ln_(6)(μ_(3)-OH)_(6)(Si Nb_(18)O_(54))_(3)}({Ln_6Si_(3)Nb_(54)})clusters hav been successfully synthesized via one-pot hydrothermal synthesis *** flower-like polyoxoanio{Ln_6Si_(3)Nb_(54)}is consisted of three heteropolyoxoniobate{Si Nb_(18)O_(54)}clusters and one unique planar equ lateral triangle-shaped{Ln_6(μ_(3)-OH)_6}cluster,which presents the highest nuclear iso-Ln-oxo cluster i PONb ***{Ln_6(μ_(3)-OH)_6}cluster,each pair ofμ_(3)-OH groups link three Dy^(3+)ions to form a sma approximate equilateral triangle-shaped{Dy_(3)(OH)_(2)}***,the three{Dy_(3)(OH)_(2)}cluster comprise a bigger approximate equilateral triangle-shaped{Dy_6(μ_(3)-OH)_6}*** reported hexanu clear{Ln_6}cluster skeletons are mostly octahedral,however,such equilateral triangle-shaped skeleton o the hexanuclear Ln-oxo cluster is first *** 1-Dy exhibits good water vapor adsorption capacit and ferromagnetic properties.

关键词： Heteropolyoxoniobate Hexanuclear iso-Ln-oxo cluster Copper complexes Water vapor adsorption Ferromagnetism

Mitigation of Deane and Hamill phenomenon in gallium nitride high-voltage power supply for electric propulsion system application

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High Voltage 2024年第1期9卷 252-265页

作者： Minghai Dong Hui li Shan Yin Kye Yak See Yingzhe Wu xiong xin School of Aeronautics&Astronautics University of Electronic Science and Technology of ChinaChengduChina School of Electrical&Electronic Engineering Nanyang Technological UniversitySingaporeSingapore School of Automation Engineering University of Electronic Science and Technology of ChinaChengduChina Innoscience(Shenzhen)Semiconductor Co.Ltd. ShenzhenChina

The step-up resonant converters are widely adopted to provide high voltage in kV-level for electric propulsion system due to their high efficiency,low mass,modularisation,and high-power *** bipolar Cockcroft-Walton voltage multiplier(BiCWVM)is a major circuit that steps up the voltage in the resonant ***,the diode nonlinearity in BiCWVM can introduce self-sustained quasi-periodic oscillations in the voltage and current waveforms,which is commonly known as the Deane and Hamill(DH)*** oscillation can lead to higher magnetic loss and control failure,and it is more likely to present in the gallium nitride-based converter due to the highfrequency *** authors aim to investigate and mitigate the DH phenomenon systematically so that proper mitigation can be *** facilitate the investigation,the circuit before the BiCWVM in the converter is derived and modelled as a voltage source v_(m)and a series inductor L_(sy).Also,the reverse recovery process of the diode in the BiCWVM can be represented by a piecewise-linear(PWL)model,with the simplified circuit and PWL model,the relationship between voltage and current under different operating conditions can be determined with *** relationship allows to understand the mechanism of diode reverse recovery in BiCWVM that leads to DH ***,a hybrid-/full-silicon carbide(SiC)design is proposed to mitigate the DH phenomenon,which is verified experimentally for a 300-kHz,5-W,20-V/1.5-kV GaN-based step-up resonant converter.

关键词： power resonant high

Giant Ln_(30)-Cluster-Embedded Polyoxotungstate Nanoclusters with Exceptional Proton-Conducting and Luminescent Properties

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CCS Chemistry 2022年第9期4卷 2938-2945页

作者： Zhong li Zhi-Hao Lv Hao Yu Yan-Qiong Sun xin-xiong li Shou-Tian Zheng State Key Laboratory of Photocatalysis on Energy and Environment College of ChemistryFuzhou UniversityFuzhouFujian 350108

Although the synthesis of giant lanthanide(Ln)-containing polyoxotungstates(POTs)has long been actively pursued,it remains challenging to encapsulate high-nuclearity Ln–O clusters in POT shells because of the highly complicated assembly *** work demonstrates a simple synthetic strategy of using lacunary POT precursors to assemble with in situ generated Ln–O clusters in the presence of basic N-containing ligands,which exert a slow-releasing effect for Ln^(3+)ions in alkaline conditions.

关键词： polyoxotungstate lanthanide highnuclearity proton conductivity luminescence

Regulation of AMPK activation by extracellular matrix stiffness in pancreatic cancer

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Genes & Diseases 2024年第3期11卷 338-350页

作者： xin Xu Yuan Fang Somaira Nowsheen Ye-xiong li Zhenkun Lou Min Deng State Key Laboratory of Molecular Oncology and Department of Radiation Oncology National Cancer Center/National Clinical Research Center for Cancer/Cancer HospitalChinese Academy of Medical Sciences and Peking Union Medical CollegeBeijing 100021China Department of General Surgery Shanghai General HospitalShanghai Jiaotong University School of MedicineShanghai 200080China Department of General Surgery Zhongshan HospitalFudan UniversityShanghai 200032China Department of Dermatology University of California San DiegoSan DiegoCA 92093USA Department of Oncology Mayo ClinicRochesterMN 55905USA

The adenosine monophosphate(AMP)-activated protein kinase(AMPK)sits at a cen-tral node in the regulation of energy metabolism and tumor *** is best known to sense high cellular ADP or AMP levels,which indicate the depletion of energy *** studies have shown that the low expression of phosphorylated AMPK is associated with a poor prognosis of pancreatic *** this study,we report that AMPK is also highly sensitive to extracellular matrix(ECM)*** found that AMPK is activated in cells when cultured under low ECM stiffness conditions and is functionally required for the metabolic switch induced by ECM *** regulation of AMPK requires the Hippo kinases but not LKB1/*** kinases directly phosphorylate AMPKa at Thr172 to activate AMPK at low ECM ***,we found AMPK activity is inhibited in patients with pancreatic ductal adenocarcinoma(PDAC)with high ECM stiffness and is associated with a poor survival *** activation of Hippo kinases by ROCK inhibitor Y-27632 in combination with the mitochondrial inhibitor metformin synergistically activates AMPK and dramatically inhibits PDAC ***,these findings establish a novel model for AMPK regulation by the mechanical properties of ECMs and provide a rationale for simultaneously targeting the ECM stiffness-Hippo kinases-AMPK signaling and low glucose-LKB1-AMPK signaling pathways as an effective therapeutic strategy against PDAC.

关键词： AMPKactivity Cellularmetabolic switch ECM stiffness Hippokinase signaling Pancreaticductal adenocarcinoma