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Label-free fluorescent strategy for sensitive detection of tetracycline based on triple-helix molecular switch and G-quadruplex

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Chinese Chemical Letters 2017年第7期28卷 1380-1384页

作者： Tian-Xiao Chen Feng Ning hai-sheng liu Ke-Feng Wu Wei Li Chang-Bei Ma School of Chemistry and Biological Engineering Changsha University of Science and Technology State Key Laboratory of Medical Genetics & School of Life Sciences Central South University

In this assay, a label-free fluorescent sensing platform based on triple-helix molecular switch（THMS） and G-quadruplex was developed for the detection of tetracycline. We demonstrated this approach by using THMS, which consists of a central section with a shortened 8-mer aptamer sequence with high affinity to tetracycline and flanked by two arm segments. G-rich oligonucleotide can specifically bind to thioflavin T（Th T） as a signal transduction probe（STP）. In the absence of tetracycline, THMS remains stable, the fluorescence of background is low. By the addition of target tetracycline, the aptamer-target binding results in the formation of a structured aptamer-target complex, which disassembles the THMS and releases the STP. The free STP self-assembles into G-quadruplex and specifically binds to Th T which generates a obvious fluorescence enhancement. Using the triple-helix molecular switch, the developed aptamer-based fluorescent sensing platform showed a linear relationship with the concentration of tetracycline ranging from 0.2 to 20.0 nmol/L. The detection limit of tetracycline was determined to be970.0 pmol/L. The assay avoids complicated modifications or chemical labeling, making it simple and cost-effective. So, it is expected that this aptamer-based fluorescent assay could be extensively applied in the field of food safety inspection.

关键词： Tetracycline Aptamer Label-free Triple-helix molecular switch G-quadruplex Thioflavin T

Theoretical Studies on the Structures and Reactions of Halocarbenoids(Ⅰ)Structures and Stability of Chlorocarbenoid CHCl_2

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Chemical Research in Chinese Universities 1997年第3期13卷 256-261页

作者： Li LI Ji-hai, FENG sheng-yu,liu Wei (Chemical College,Shandong University,Jinan, 250100) SHANDONG UNIV CHEM COLLJINAN 250100PEOPLES R CHINA

The chlorocarbenoid , CHCl2Li , was studied by means of ab initio molecular or- bital theory. Three equilibrium structures and two isomerization transition states were located. The calculations showed that the three-membered ring structure is the most stable. The 'classical tetrahedral' structure is not the local minimum on the potential energy surface.

关键词： Chlorocarbenoid isomeric structure Ab initio molecular orbital calcu- lation

Fractal model of spontaneous imbibition in low-permeability reservoirs coupled with heterogeneity of pore seepage channels and threshold pressure

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Petroleum Science 2024年第2期21卷 1002-1017页

作者： Ming-sheng Zuo Hao Chen Xi-Liang liu hai-Peng liu Yi Wu Xin-Yu Qi National Key Laboratory of Petroleum Resources and Engineering China University of Petroleum(Beijing)Beijing102249China College of Safety and Ocean Engineering China University of Petroleum(Beijing)Beijing102249China

Spontaneous imbibition(SI)is an important mechanism for enhancing oil recovery in low-permeability *** to the strong heterogeneity,and the non-Darcy flow,the construction of SI model for lowpermeability reservoirs is extremely ***,traditional SI models based on single or averaged capillary tortuosity ignore the influence of heterogeneity of pore seepage channels and the threshold pressure(TP)on ***,in this work,based on capillary model and fractal theory,a mathematical model of characterizing SI considering heterogeneity of pore seepage channels is *** this basis,the threshold pressure was introduced to determine the pore radius at which the wetted phase can displace *** proposed new SI model was verified by imbibition experimental *** study shows that for weakly heterogeneous cores with permeability of 0-1 m D,the traditional SI model can characterize the imbibition process relatively accurately,and the new imbibition model can increase the coefficient of determination by 1.05 ***,traditional model has serious deviations in predicting the imbibition recovery for cores with permeability of 10-50 m *** new SI model coupling with heterogeneity of pore seepage channels and threshold pressure effectively solves this problem,and the determination coefficient is increased from 0.344 to 0.922,which is increased by2.68 *** low-permeability reservoirs,the production of the oil in transitional pores(0.01-0.1μm)and mesopores(0.1-1μm)significantly affects the imbibition recovery,as the research shows that when the heterogeneity of pore seepage channels is ignored,the oil recovery in transitional pores and mesopores decreases by 7.54%and 4.26%,*** analysis shows that increasing interfacial tension,decreasing contact angle,oil-water viscosity ratio and threshold pressure will increase imbibition *** addition,there are critical values for the influence of these factors o

关键词： Spontaneous imbibition Low-permeability reservoir Fractal model Threshold pressure Capillary tube

Improving mathematical model of burden distribution and correcting chute angle to cope with fluctuation of stock line

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Journal of Iron and Steel Research International 2024年第2期31卷 342-356页

作者： Jian-sheng Chen Wen-guo liu Hao Guo Wang Ding Qing-guo Xue Jing-song Wang hai-bin Zuo State Key Laboratory of Advanced Metallurgy University of Science and Technology BeijingBeijing100083China MCC Capital Engineering&Research Incorporation Limited Beijing100176China Hunan Valin Xiangtan Iron and Steel Co. Ltd.Xiangtan411101HunanChina

Accurate evaluations of the burden distribution are of critical importance to stabilize the operation of blast *** mathematical model and discrete element method(DEM)are two attractive methods for predicting burden *** on DEM,the initial velocities of the pellet,sinter,and coke were calculated,and the velocity attenuations of the above three particles between the burden and the chute were *** initial velocity and velocity attenuation were applied to a mathematical model for improving the ***,based on the improved model,a scheme for rectifying the chute angles was proposed to address the fluctuation of the stock line and maintain a stable burden *** validity of the scheme was confirmed via a stable burden distribution under different stock *** mathematical model has been successfully applied to evaluate the online burden distribution and cope with the fluctuation of the stock line.

关键词： Burden distribution Mathematical model Discrete element method Velocity attenuation Stock line fluctuation

Transient Stability Analysis and Design of VSGs with Different DC-Link Voltage Controllers

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CSEE Journal of Power and Energy Systems 2024年第2期10卷 593-604页

作者： Chao Shen Wei Gu Wanxing sheng Keyan liu School of Electrical Engineering Southeast UniversityNanjingChina Power Distribution Research Department China Electric Power Research InstituteBeijing 100192China

Virtual synchronous control has been widely studied for the advantages of emulating inertia for voltage source converters (VSCs). A constant dc-link voltage is usually assumed in existing literature to estimate transient stability of virtual synchronous generators (VSGs). However, actual power supply in the dc-side of VSGs is limited and different dc-link voltage controllers are needed to achieve power balance between DC side and AC side. Addition of dc-link voltage controller has great influence on transient behavior of VSGs, which has not been investigated by previous research. To fill this gap, this paper gives insights into the effect of dc-link voltage dynamics on transient stability of VSGs. First, two typical kinds of VSGs with dc-link voltage controllers are introduced. Then, mathematical models considering dc-link dynamics are established and the effect of dc-link voltage controllers on transient synchronization stability of VSGs is revealed through equal area criterion (EAC). It is found that dc-link voltage controller would reduce stability margin of VSGs and design-oriented transient stability analysis is carried out quantitively using critical clearing time (CCT). Finally, simulation results are given to validate correctness of theoretical analysis.

关键词： DC-link voltage dynamics equal area criterion(eac) transient synchronization stability virtual synchronous generator(VSG)

Interaction mechanism between BaZrO_(3)/Y_(2)O_(3) refractory and Ti_(2)Ni alloy melts

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Journal of Iron and Steel Research International 2024年第6期31卷 1376-1388页

作者： Xiao Hou Guang-yao Chen Jian liu Ming-rui Lv Fei-hai Yu Qi-sheng Feng Rong-bin Li Xiong-gang Lu Chong-he Li State Key Laboratory of Advanced Special Steel and Shanghai Key Laboratory of Advanced Ferromeallurgy and School of Materials Science and Engineering Shanghai UniversityShanghai 200072China Shanghai Special Casting Engineering Technology Research Center Shanghai 201605China Zhejiang Institute of Advanced Materials Shanghai UniversityJiashan 314100ZhejiangChina School of Materials Science and Engineering Shanghai DianJi UniversityShanghai 201306China

The titanium alloys with highly chemical activity require stable crucible refractories that can withstand the erosion of alloy *** phase composition and microstructure are crucial factors that affect the stability of the refractory *** effect of Y_(2)O_(3) on the composition and microstructure of BaZrO_(3) crucible was systematically investigated,and the improved mechanism of the stability of BaZrO_(3)/Y_(2)O_(3) crucible was clarified in comparison with the BaZrO_(3) *** results showed that the erosion layer thickness of the BaZrO_(3)/Y_(2)O_(3) crucible was only 63μm,which was far less than that in the BaZrO_(3) crucible(485μm),and the erosion layer in the BaZrO_(3)/Y_(2)O_(3) crucible also exhibited a higher density than that in the BaZrO_(3) *** the sintering,Y_(2)O_(3) could improve the densification of the BaZrO_(3) crucible due to the solid solution effect between Y_(2)O_(3) and ZrO_(2),which also caused the evaporation of BaO,resulting in the generation of a Y_(2)O_(3)(ZrO_(2))film on the surface of the ***,the Y_(2)O_(3)(ZrO_(2))had higher thermodynamic stability than Y_(2)O_(3),confirming that the BaZrO_(3)/Y_(2)O_(3) crucible with high density exhibited a superior erosion resistance to titanium *** dual-phase structure provides a strategy to design a long-life and stable refractory for melting titanium alloys.

关键词： Barium zirconate Yttrium oxide Dual-phase refractory Titanium alloy Interaction

Using Copula functions to predict climatic change impacts on floods in river source regions

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Advances in Climate Change Research 2024年第3期15卷 406-418页

作者： Ting-Xing CHEN hai-Shen LYU Robert HORTON Yong-Hua ZHU Ren-sheng CHEN Ming-Yue SUN Ming-Wen liu Yu LIN The National Key Laboratory of Water Disaster Prevention College of Hydrology and Water ResourcesHohai UniversityNanjing 2098China College of Hydrology and Water Resources Hohai UniversityNanjing 210098China Departmentof Agronomy lowa State UniversityAmes IA5oollUSA Qilian Alpine Eology and Hydrology Research Station Northwest Instiuteof Eco-Environmentand ReourcesChinese Academy of SciencesLanzhou0000 China

Flood frequency in river source regions is significantly affected by rainfall and snowmelt as part of climatic changes.A traditional univariate flood frequency analysis cannot reflect the complexity of floods,and when used in isolation,it can only underestimate flood *** effective flood prevention and mitigation,it is essential to consider the combined effects of precipitation and *** functions can effectively quantify the joint distribution relationship between floods and their associated variables without restrictions on their distribution *** study uses copula functions to consider a multivariate probability distribution model of flood peak flow(Q)with cumulative snowmelt(CSm)and cumulative precipitation(CPr)for the Hutubi River basin located in northern Xinjiang,*** joint frequencies of rainfall and snowmelt floods are predicted using copula models based on the Coupled Model Intercomparison Project Phase 6 *** results show that Q has a significant positive correlation with 24-d CSm(r=0.559,p=0.002)and 23-d CPr(r=0.965,p<0.05).Flood frequency will increase in the future,and mid-(2050e2074)and long-term(2075e2099)floods will be more severe than those in the near-term(2025e2049).The probability of flood occurrence is higher under the SSP2-4.5 and SSP1-2.6 scenarios than under *** during the historical period(1990e2014)led to extreme floods,and increasing future precipitation trends are found to be *** increases with rising temperatures and occurs earlier than estimated,leading to an earlier flood period in the basin and more frequent snowmelt *** Q under the joint return period is larger than that during the same univariate return *** difference indicates that neglecting the interaction between precipitation and snowmelt for floods leads to an underestimation of the flood risk(with underestimations ranging from 0.3%to 22%).The underestimations decrease with an increase

关键词： Climate change Flood frequency Copula CMIP6 River source regions

Super P and MoO2/MoS2 co-doped gradient nanofiber membrane as multi-functional separator for lithium–sulfur batteries

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Rare Metals 2024年第9期43卷 4263-4273页

作者： Xin Liang Dong-Qing Zhao Qian-Qian Huang sheng Liang Li-Li Wang Lei Hu Ling-Li liu Kun-Hong Hu Chong-hai Deng sheng Cheng Er-Tao Zhu Hua-Xia Deng School of Energy Materials and Chemical Engineering LIB Technology Center of Anhui ProvinceHefei University Instrumental Analysis Centre Hefei University of Technology Hefei Youngy Energy Materials Co. Ltd. Department of Modern Mechanics University of Science and Technology of China

Lithium-sulfur battery is one of the most promising battery systems for industrialization due to its high theoretical specific capacity and high energy ***,the??shuttle effect??has restrained the advancement of lithium-sulfur *** this work,a gradient-structured nanofiber membrane with pure gelatin on one side and Super P-MoO2/MoS2-gelatin on the other side was created using a multi-step electrostatic spinning technique,which was applied for multi-functional separator for lithium-sulfur *** pure gelatin layer facing the anode side primarily homogenizes the lithium flux,whereas the Super P-MoO2/MoS2-gelatin layer facing the cathode side primarily adsorbs polysulfides by physical and chemical adsorption and enhancing polysulfide conversion *** findings demonstrate that even after 150 cycles at 0.2C,the lithium-sulfur battery can still sustain a discharge-specific capacity of 572.3 mAh·*** used with Li||Li symmetric batteries,it has a cycle life of more than 1200 *** commercialization of lithium-sulfur batteries is given a fresh idea by this straightforward preparation technique.

关键词： Li–S battery Membrane MoO2/MoS2 Nanofiber

Recent breakthrough in AI-driven materials science:tech giants introduce groundbreaking models

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Materials Futures 2024年第2期3卷 170-174页

作者： Miao liu sheng Meng Institute of Physics Chinese Academy of SciencesBeijing 100190People’s Republic of China Songshan Lake Materials Laboratory DongguanGuangdong 523808People’s Republic of China

A close look at Google’s GNoME inorganic materials dataset(Merchant et al 2023 Nature 62480–85),and 11 things you would like to know.

关键词： AI GNoME dataset AI+materials science