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Temperature-dependent of Nonlinear Optical Conductance of Graphene-based Systems in High-intensity Terahertz Field

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Nano-Micro Letters 2014年第2期6卷 153-162页

作者： jing lv Rui-yang Yuan Hui Yan Laboratory of Thin Film Materials Beijing University of Technology Center of Theoretical Physics Department of PhysicsCapital Normal University

For multi-photon processed with the linear dispersion in the high-intensity terahertz(THz) field,we have systematically investigated the temperature-dependent nonlinear optical response of graphene-based systems, including single layer graphene, graphene superlattice and gapped graphene. In the intrinsic single layer graphene system, it demonstrates that, at low temperature, nonlinear optical conductivities of the thirdand fifth-order are respectively five and ten orders of magnitude larger than the universal conductivity with high-intensity and low frequency THz *** the graphene superlattice and gapped graphene systems, the optical responses enhanced because of the anisotropic massless and massive Dirac fermions.

关键词： Nonlinear Graphene Terahertz Conductance Transmittance

Flame-retarding battery cathode materials based on reversible multi-electron redox chemistry of phenothiazine-based polymer

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Journal of Energy Chemistry 2020年第8期29卷 256-262,I0009页

作者： jing lv jing Ye Gaole Dai Zhihui Niu Yi Sun Xiaohong Zhang Yu Zhao Institute of Functional Nano and Soft Materials(FUNSOM) Jiangsu Key Laboratory for Carbon-Based Functional Materials and DevicesSoochow UniversitySuzhou 215123JiangsuChina Analytical and Testing Centre Soochow UniversitySuzhou 215123JiangsuChina School of Physics and Optoelectronic Engineering Shandong University of TechnologyZibo 250049ShandongChina College of Textile and Clothing Engineering Soochow UniversitySuzhou 215123JiangsuChina

Polymeric organic battery materials are promising alternatives to the transition-metal-based ones owing to their enriched chemistries. However, the flammability of organic compounds brings in serious concern on battery safety. In addition to use flame-retarding electrolyte/electrolyte additives or battery separators,flame retardancy can readily be achieved through the integration of flame-retarding unit into the polymer backbone, imparting the flame retardancy permanently. The as-designed polymer based on phenothiazine shows significantly shortened self-extinguished time without deteriorating its intrinsic thermodynamic and electrochemical properties. Moreover, two electron per phenothiazine molecule is realized for the first time in a highly reversible manner with discharge voltages of 3.52 V and 4.16 V versus Li+/Li and an average capacity of ca. 120 mAh g-1 at a current rate of 2 C. The origin of the reversibility is investigated through density functional theory(DFT) calculations. These findings address the importance of molecular design for safer and more stable organic materials for batteries.

关键词： Flame retardancy Molecular design Phenothiazine Batteries Energy storage

Controllable synthesis of core-shell Co@C@SiO2 catalysts for enhancing product selectivity in Fischer-Tropsch synthesis by tuning the mass transfer resistance

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Journal of Energy Chemistry 2020年第12期29卷 199-206页

作者： Yao Chen Xin Li Liya Dai Mehar U Nisa Chengchao Liu Shuai lv jing lv Zhenhua Li Key Lab for Green Chemical Technology of Ministry of Education School of Chemical Engineering and TechnologyCollaborative Innovation Center of Chemical Science and Engineering(Tianjin)Tianjin UniversityTianjin 300072China Key Laboratory of Catalysis and Materials Science of the State Ethnic Affairs Commission&Ministry of Education College of Chemistry and Materials ScienceSouth-Central University for NationalitiesWuhan 430074HubeiChina

Fischer-Tropsch synthesis(FTS) is the key step in converting syngas into clean fuels. Traditional supported catalysts for FTS are problematic because the active metal crystalline size is positively related to metal loading. Therefore, increasing active metal loading may reduce the cobalt time yield(CTY) since a high CTY is usually obtained when the Co size is 8 nm. Here, a ZIF-67(Zeolitic imidazolate framework-67) with a MOF(Metal organic framework) structure is used as a precursor to prepare the Co@C catalyst with not only high cobalt loading(55.6 wt%) but also with a small cobalt crystal size(as small as 8.6 nm). Coreshell Co@C@SiO2-X catalysts with different SiO2 shell thicknesses were successfully prepared by coating different amounts of TEOS on the outer surface of Co@C to modify product selectivity. Compared with40 wt% Co/SiO2 catalyst, core-shell Co@C@SiO2-X catalysts exhibited improved FTS performance. Furthermore, different gaseous hourly space velocities(GHSVs) were used to obtain CO conversion at similar levels to compare CTY and the turnover frequency(TOF). Among the catalysts, the Co@C@SiO2-1 catalyst, with its better mass transfer ability and suitable hydrophilic property, presented the highest TOF(9.75 × 10-3 s-1) and lowest CH4 selectivity(9.75%). In addition, heavy hydrocarbons were effectively suppressed with the increase in shell thickness due to the increased mass transfer resistance.

关键词： Fischer-Tropsch synthesis ZIF-67 Product selectivity Core-shell catalyst Hydrophilic property

Semiparametric Model Averaging for Ultrahigh-Dimensional Conditional Quantile Prediction

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Acta Mathematica Sinica,English Series 2023年第6期39卷 1171-1202页

作者： Chao Hui GUO jing lv Hu YANG jing Wen TU Chen Xiao TIAN School of Mathematical Sciences Chongqing Normal UniversityChongqing 401331P.R.China School of Mathematics and Statistics Southwest UniversityChongqing 400715P.R.China College of Mathematics and Statistics Chongqing UniversityChongqing 401331P.R.China College of Finance University of International Business and EconomicsBeijing 100020P.R.China

In this paper,we develop a flexible semiparametric model averaging marginal regression procedure to forecast the joint conditional quantile function of the response variable for ultrahighdimensional ***,we approximate the joint conditional quantile function by a weighted average of one-dimensional marginal conditional quantile functions that have varying coefficient ***,a local linear regression technique is employed to derive the consistent estimates of marginal conditional quantile ***,based on estimated marginal conditional quantile functions,we estimate and select the significant model weights involved in the approximation by a nonconvex penalized quantile *** some relaxed conditions,we establish the asymptotic properties for the nonparametric kernel estimators and oracle estimators of the model averaging *** further derive the oracle property for the proposed nonconvex penalized model averaging ***,simulation studies and a real data analysis are conducted to illustrate the merits of our proposed model averaging method.

关键词： Kernel regression model averaging oracle property penalized quantile regression ultrahigh-dimension data

Chain Dynamics Heterogeneity in Plasticized Poly(vinyl butyral)(PVB) as Elucidated by Solid-State NMR

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Chinese Journal of Polymer Science 2024年第1期42卷 113-124,I0010页

作者： jing lv Xu Chen Zi-Shuo Wu Ya-Hui Li Wei Chen National Synchrotron Radiation Laboratory Anhui Provincial Engineering Laboratory of Advanced Functional Polymer FilmCAS Key Laboratory of Soft Matter ChemistryUniversity of Scienceand Technology of ChinaHefei 230026China

The chain dynamics heterogeneity of the poly(vinyl butyral)(PVB) plasticized by triethylene glycol bis(2-ethylhexa noate)(TEG-EH) was investigated by various solid-state NMR *** plasticized PVB shows two domains in distinct molecular dynamics differences,namely,rigid and soft domains,where the latter is the plasticizer-rich *** time domain low field NMR was first used to investigate the dynamics heterogeneity of the plasticized PVB,and the results show the decreasing activated energy of components in the soft domain of plasticized PVB(E_a=20.2 kJ/mol) as compared with that of the pristine one(E_a=24.3 kJ/mol).Detailed dynamics heterogeneity was obtained by high-field NMR with site-specific *** quadrupole-echo ~2H-NMR was adopted to elucidate the dynamics heterogeneity of the vinyl alcohol(VA) units,where only the hydroxyl group of VA is *** ~1H-^(13)C WISE NMR spectra show that there is not much difference in the mobility of the VB unit in PVB with and without plasticizer,whereas the glass transition temperature differed by approximately 53℃.This is further supported by Torchia's T_1 relaxation *** origin of such an unusual phenomenon is attributed to the critical role of the remaining VA(~22%) in the soft domain,where the VA units locally aggregate through hydrogen ***,the existence of a mobility gradient in the VB unit has been ***,the mobility difference for VB with different stereo-geometry(meso or racemic conformation) is observed for the first *** indicates the importance of modulating the ratio of meso over racemic VB for controlling the macroscopic perfo rmance of PVB.

关键词： Poly(vinyl butyral) Dynamics heterogeneity Plasticizer Solid state NMR

Importance of metal location in M-H zeolite for synergistically catalyzing dimethyl ether carbonylation

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Chinese Journal of Chemical Engineering 2022年第1期35卷 350-357页

作者： Shiyue Li Shouying Huang Kai Cai Ying Li jing lv Xinbin Ma Key Laboratory for Green Chemical Technology of Ministry of Education Collaborative Innovation Center of Chemical Science and EngineeringSchool of Chemical Engineering and TechnologyTianjin UniversityTianjin 300350China

Mordenite(MOR)has shown great potential to catalyze dimethyl ether(DME)carbonylation to methyl acetate(MA)in *** synergy between metal species and Brønsted acid sites accelerates DME *** we designed and prepared two catalysts with different Ag locations by seed-directed growth method and two-step impregnation method(named as Ag@HMOR and Ag/HMOR-out,respectively),to explain the effect of Ag location on catalytic *** results of TEM,XPS,CO-IR and UV–Vis showed that Ag species mainly presented as Ag^(0) species over both Ag@HMOR and Ag/***,Ag^(0) species mainly located in the micropores of Ag@HMOR,while as for Ag/HMOR-out,Ag^(0) mainly existed on external *** comparing the performance of the catalysts with different Ag positions,we confirmed that the Ag^(0) species encapsulated in the channels of HMOR promoted the DME carbonylation,which revealed the importance of spatial adjacency on the acid-metal catalysts.

关键词： Dimethyl ether Carbonylation Silver modification Metal location

An Improved Hybrid Collaborative Filtering Algorithm Based on Tags and Time Factor

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Big Data Mining and Analytics 2018年第2期1卷 128-136页

作者： Chunxia Zhang Ming Yang jing lv Wanqi Yang the School of Computer Science and Technology Nanjing Normal University

The Collaborative Filtering(CF) recommendation algorithm, one of the most popular algorithms in Recommendation Systems(RS), mainly includes memory-based and model-based methods. When performing rating prediction using a memory-based method, the approach used to measure the similarity between users or items can significantly influence the recommendation performance. Traditional CFs suffer from data sparsity when making recommendations based on a rating matrix, and cannot effectively capture changes in user interest. In this paper, we propose an improved hybrid collaborative filtering algorithm based on tags and a time factor(TTHybridCF), which fully utilizes tag information that characterizes users and items. This algorithm utilizes both tag and rating information to calculate the similarity between users or items. In addition, we introduce a time weighting factor to measure user interest, which changes over time. Our experimental results show that our method alleviates the sparsity problem and demonstrates promising prediction accuracy.

关键词： recommendation system similarity tag time factor

A new 3D cupric coordination polymer as chemiresistor humidity sensor:narrow hysteresis,high sensitivity,fast response and recovery

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Science China Chemistry 2017年第9期60卷 1197-1204页

作者： Xiao-jing lv Ming-Shui Yao Guan-E Wang Yan-Zhou Li Gang Xu State Key Laboratory of Structural Chemistry Fujian Institute of Research on the Structure of MatterChinese Academy of Sciences University of Chinese Academy of Sciences Chinese Academy of Sciences

A new three-dimensional coordination polymer composed of Cu2+ centres and semiquinoid linkers (dhbq(2-)) was synthesized which was composed by two independent, enantiomeric, interpenetrated [Cu-2(dhbq)(3)](2-) networks with (10,3)-a topology. The compound has good water stability and typical behaviors of semiconductor, whose conductivity increases along with raising temperature. The chemiresistive humidity sensor made from this material shows good properties including linear sensitivity, high response, fast response and recovery, and particularly narrow hysteresis during humidity adsorption and desorption.

关键词： coordination polymer, chemiresistive humidity sensor, narrow hysteresis, fast response & recovery

Antiosteoporotic Tetrahydroxanthone Dimers from Aspergillus brunneoviolaceus FB-2 Residing in Human Gut

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Chinese Journal of Chemistry 2021年第6期39卷 1580-1586页

作者： Xiao-jing lv Fei Ding Ying-Jie Wei Ren-Xiang Tan State Key Laboratory Cultivation Base for TCM Quality and Efficacy Nanjing University of Chinese MedicineNanjingJiangsu 210023China State Key Laboratory of Pharmaceutical Biotechnology School of Life SciencesNanjing UniversityNanjingJiangsu 210023China

A complex community of human-associated microorganisms plays diversely important roles in maintaining health,and the metabolites help to define whether a particular human-associated microbe is a friend or a *** work shows that Aspergillus brunneoviolaceus FB-2,derived from the stool of a healthy individual,produces a family of antiosteoporotic xanthone dinners including penibishexahydroxanthone A(1)and brunneoxanthones A-E(2-6,undescribed previously).The structures of 1-6 were elucidated by MS and NMR spectroscopic analysis,and the absolute configuration of 2 was established by X-ray *** 4-6 are relatively rare examples of highly oxidized heterodimeric xanthones with an 8-ketone ***,the prednisolone-induced osteoporotic zebrafish enabled our demonstration that the antiosteoporotic effects of 1-6 are dose-dependent.

关键词： Aspergillus brunneoviolaceus Gut-associated fungus Natural products Structure elucidation Biological activity