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Quantum tunneling of ultracold atoms in optical traps

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Frontiers of physics 2014年第2期9卷 137-152页

作者： jian-Hua wu Ran Qi An-chun ji wu-Ming Liu Beijing National Laboratory for Condensed Matter Physics Institute of Physics Chinese Academy of Sciences Beijing 100190 China

We review our theoretical advances in quantum tunneling of BoseEinstein condensates in optical traps and in microcavities. By employing a real physical system, the frequencies of the pseudo Goldstone modes in different phases between two optical traps are studied respectivdy, which are tile crucial feature of the non-Abelian Joseptmon effect. When the optical lattices are under gravity, we investigate the quantum tummling in the ＂Wannier-Stark localization＂ regime and ＂Lan（lau Zener tunneling＂ regime. We finally get the total decay rate and the rate is valid over the entire range of temperatures. At high temperatures, we show how the decay rate reduces to the appropriate results for the classical thermal activation. At hltermediate temperatures, the results of tile total decay rate are consistent with the thermally assisted tunneling. At low temperatures, we obtain the pure quantmn tunneling ultimately. And we study the alternating-current and direct-current （ac and de） photonic 3osephson effects in two weakly linked microcavities containing ultracold two-level atones, which allows for direct observation of the effects. This enables new investigations of the effect of maw-body physics in strongly coupled atom-cavity systems and provides a strategy for constructing novel interference devices of coherent photons. In addition, we propose the experimental protocols to observe these quantmn tunneling of Bose- Einstein condensates.

关键词： quantum tunneling Josephson effect Landau-Zener tunneling atom-cavity

Equilibrium Crystallization Temperature of Syndiotactic Polystyrene γ Form

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Chinese Journal of Polymer Science 2018年第6期36卷 749-755页

作者： Hai Wang chun-ji wu Dong-Mei Cui Yong-Feng Men State Key Laboratory of Polymer Physics and Chemistry Changchun Institute of Applied ChemistryChinese Academy of Sciences

The crystallization behavior of syndiotactic polystyrene（s PS） γ form undergoing annealing at various temperatures was investigated using the thermodynamic phase diagram based on Strobl＇s crystallization theory. On the basis of the differential scanning calorimetric results, it was observed that γ form melt-recrystallization occurred at a higher temperature with the increasing lamellar thickness, which resulted from the pre-annealing at the elevating temperature after acetone induced crystallization. Further temperature dependent small-angle X-ray scattering（SAXS） measurement revealed the evolution of the γ form lamellae upon heating until phase transition, involving three different regimes： lamellae stable region（25-90 °C）, melt-recrystallization region（90-185 °C） and pre-phase transition region（185-195 °C）. As a result, recrystallization line, equilibrium recrystallization line and melting line were developed for the s PS γ form crystallization process. Since the melt of γ form involved a γ-to-α/β form phase transition, the melting line was also denoted as the phase transition line in this special case. Therefore, the equilibrium crystallization temperature and melting（phase transition） temperatures were determined at around 390 and 220 °C on the basis of the thermodynamic phase diagram of the s PS γ form.

关键词： Syndiotactic polystyrene γ form Crystallization behavior Equilibrium crystallization temperature Equilibrium melting temperature

A Comparative Study on Hydrodynamics and Hydrochemistry Coupled Simulations of Drainage Pipe Crystallization Blockage in Karst Tunnels

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Journal of Earth Science 2022年第5期33卷 1179-1189页

作者： Dian-Guang Liu Yun Yang Cheng-Jun Mao jian-Feng wu ji-chun wu School of Earth Sciences and Engineering Hohai UniversityNanjing211100China Key Laboratory of Surficial Geochemistry Ministry of EducationDepartment of HydrosciencesSchool of Earth Sciences and EngineeringNanjing UniversityNanjing210023China

Drainage pipe system is the requisite component of the traffic tunnels in Karst *** reveal the dynamic process of crystallization blockage in drainage pipes,a novel hydrodynamics and hydrochemistry coupled simulation model was developed for calculating the deposition rate of CaCO_(3) fouling in pipeline *** adhering to the pipe walls involve a deformable domain with moving geometric boundaries,and moving mesh and level set methods are proposed for simulation of for tunnel turbulence and crystallization fouling *** simulation results are compared with the experimental results showing similar *** effects of temperature,flow velocity,and solution concentration on crystallization blockage were analyzed by comparative simulation *** simulation results show that:(1)the moving mesh method simulated nozzle shrinkage caused by crystalline deposition,without accounting for geometric topology shape ***,the level set method tracked the moving topology and thus can simulate the process of complete blockage;(2)the flow velocity in the longitudinal pipe generally exceeded that in the transverse pipe,and the CaCO_(3) crystal concentration in the transverse pipe eclipsed that in the longitudinal pipe,which meant crystallization blockages primarily occurred in the transverse pipe;(3)the temperature and concentration correlated positively with the crystallization rate,while the crystal precipitation value decreases with the increasing of inlet flow velocity *** study advances a hydrodynamics and hydrochemistry coupled crystallization blockage model to provide technical support for the early identification of crystallizationinduced pipe blockage in the drainage system in karst tunnel sites.

关键词： karst tunnel crystallization blockage numerical simulation moving mesh level set engineering geology

Human impacts on runoff regime of middle and lower Yellow River

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Water Science and Engineering 2011年第1期4卷 36-45页

作者： Yan-fang SANG Dong WANG ji-chun wu Qing-ping ZHU Ling WANG Department of Hydrosciences School of Earth Sciences and Engineering Nanjing University Nanjing 210093 P. R. China China Water International Engineering Consulting Co. Ltd. Beijing 100053 P.. R. China Hydrology Bureau of Yellow River Conservancy Committee of Ministry of Water Resources Zhengzhou 450001 P. R. China

In this study, the 54-year （1950 to 2003） monthly runoff series from February, April, August, and November, as well as the annual runoff series, measured at both Huayuankou and Lijin hydrological stations were chosen as representative data, and the continuous wavelet transform （CWT） was applied to analyze the impacts of human activities on the runoff regime of the middle and lower Yellow River. A point of change in 1970 was first determined, and the observed series before 1970 were considered natural runoff while those after 1970 were restored according to linear trends. Then, the CWT was applied to both the observed and restored runoff series to reveal their variations at multi-temporal scales, including the five temporal ranges of 1-4, 6-8, 9-12, 16-22, and 22-30 years, and the trend at the temporal scale of 54 years. These analysis results are compared and discussed in detail. In conclusion, because of the impacts of human activities, there have been significant changes in the runoff regime in the middle and lower Yellow River since 1970. The decaying tendency of annual runoff has become more pronounced, and the inner-annual distribution of runoff has changed, but human activities have had little impact on the periodic characteristics of runoff.

关键词： time series analysis wavelet analysis runoff human activity Yellow River

Thermal effect of the accumulated water with different depths on permafrost subgrade in cold regions

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Advances in Climate Change Research 2023年第2期14卷 179-189页

作者： Er-Xing PENG Xiao-Ying HU Yu SHENG ji-chun wu Wei CAO Qi-Fan YANG Xiang-Bin ZHAO ji CHEN State Key Laboratory of Frozen Soil Engineering Northwest Institute of Eco-Environment and ResourcesChinese Academy of SciencesLanzhou 730000China School of Civil Engineering Lanzhou University of TechnologyLanzhou 730050China Beiluhe Observation and Research Station on Frozen Soil Engineering and Environment in Qinghai‒Tibet Plateau State Key Laboratory of Frozen Soil EngineeringNorthwest Institute of Eco-Environment and ResourcesChinese Academy of SciencesLanzhou 730000China

In cold regions,the thermal effect of accumulated water on underlying permafrost and permafrost subgrade remains a significant hazard causing engineering *** depth of accumulated water may be an important influence factor of permafrost thermal stability,but there is lack of qualitative and quantitative research about *** this study,equivalent thermal conductivity theory and solid heat transfer theory have been used to establish the calculation model for simulating heat transfer in water and ***,the accuracy and reliability of the calculation model are checked by monitored data and subsequently used to analyze the thermal erosion of water on underlying permafrost and permafrost under the *** simulation results show that shallow water can protect permafrost and deeper water disrupts the thermal stability of underlying *** thermal effect extent of water is primarily determined by its depth,and the concept of critical depth and stable depth of accumulated water has been ***,the temperature field of permafrost under embankment can be changed by the slope toe *** addition,the thermal effect range of the slope toe water is limited by the thermal influence radius,which increases with the depth of standing *** findings provide support as well as a fundamental base for environmental issues arising from the accumulated *** observations will,thus,also be valuable to further engineering environment studies in cold regions.

关键词： Accumulated water Water depth Permafrost Embankment Thermal effect

Synthesis of Ultraviolet Absorption Polylactide via Immortal Polymerization of rac-Lactide Initiated by a Salan-yttrium Catalyst

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Chinese Journal of Polymer Science 2018年第2期36卷 202-206页

作者： Wei Zhao Chuan-Yang Li chun-ji wu Xin-Li Liu Ze-Huai Mou Chang-Guang Yao Dong-Mei Cui State Key Laboratory of Polymer Physics and Chemistry Changchun Institute of Applied ChemistryChinese Academy of SciencesChangchun 130022China University of Chinese Academy of Sciences Changchun BranchChangchun 130022China College of Bioresources Chemical and Materials Engineering Shaanxi University of Science and TechnologyXi'an 710021China

A highly efficient strategy for the synthesis of polylactide with the UV absorption ability was established by employing a Salan-yttrium complex（acting as a fast runing catalyst） combined with large excess hydroxyl functionalized benzophenone, BP′-OH. During polymerization, BP′-OH, acting as the chain transfer agent, attached to the active rare-earth metal catalyst via a rapid-reversible exchange reaction to initiate the polymerization. Thus, more polyester chains appeared to grow from one active metal species, and the UV absorption fragments were incorporated into the polymer chains at specific sites, in situ. A high productivity up to 1000 mol LA/mol（Salan-Y） was successfully achieved and 100 BP′-labeled PLA chains grew from each active metal center.

关键词： Yttrium catalyst Ring-opening polymerization Polylactide Ultraviolet absorption

Water budgets in an arid and alpine permafrost basin:Observations from the High Mountain Asia

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Advances in Climate Change Research 2024年第5期15卷 830-844页

作者： Qing-Feng WANG Hui-Jun jiN Dong-Liang LUO Yu SHENG Jun WEN Chien-Lu PING Mark H.CLARK Qiang MA Xiao-Ying jiN ji-chun wu Yu-Zhong YANG Qiang LI Raul D.SERBAN Daqing YANG Victor F.BENSE Qing-Bai wu Key Laboratory of Cryospheric Science and Frozen Soil Engineering Northwest Institute of Eco-Environment and ResourcesChinese Academy of SciencesLanzhou 730000China Qinghai-Beiluhe Plateau Frozen Soil Engineering Safety National Oseration and Research Station Norhwes Institute of Eco-Environment and Resources Chinese Academy of Sciences Lanzhou 730000China School of Civil Engineering and Transportation China-Russia Joint Laboratory of Cold Regions Engineering and Environmentand Permafrost InstituteNortheast Forestry UniversityHarbin 150040 China College of Atmospheric Science Plateau Atmosphere and Environment Key Laboratory of Sichuan ProvinceChengdu University of Information Technology Chengdu 610225China Agricultural and Forestry Experiment Station University of Alaska FairbanksPalmer Research CenterPalmer 99645USA USDA-Natural Resources Conservation Service Palmer 99645USA College of Water Conservancy and Hydropower Engineering Gansu Agricultural UniversityLanzhou 730070China Institute for Alpine Environment Eurac ResearchBolzano 39100Ilialy Faculty of Agricultural Environmental and Food SciencesFree University of Bozen-BolzanoBolzano 39100Italy Watershed Hydrology and Ecology Division Environment and Climate Change CanadaVictoria V8S 3V3Canada Institute of Tibetan Plateau Research Chinese Academy of SciencesBeijing 100101China Hydrology and Quantiative Water Management Group Department of Environmental SciencesWageningen UniversityWageningen 6700The Netherlands

Ground freeze-thaw processes have significant impacts on infiltration,runoff and ***,there are still critical knowledge gaps in understanding of hydrological processes in permafrost regions,especially of the interactions among permafrost,ecology,and *** this study,an alpine permafrost basin on the northeastern Qinghai-Tibet Plateau was selected to conduct hydrological and meteorological *** analyzed the annual variations in runoff,precipitation,evapotranspiration,and changes in water storage,as well as the mechanisms for runoff gen-eration in the basin from May 2014 to December *** annual flow curve in the basin exhibited peaks both in spring and autumn *** high ratio of evapotranspiration to annual precipitation(>1.O)in the investigated wetland is mainly due to the considerably underestimated‘observed'precipitation caused by the wind-induced instrumental error and the neglect of snow *** stream flow from early May to late October probably came from the lateral discharge of subsurface flow in alpine *** study can provide data support and validation for hydrological model simulation and prediction,as well as water resource assessment,in the upper Yellow River Basin,especially for the headwater *** results also provide case support for permafrost hydrology modeling in ungauged or poorly gauged watersheds in the High Mountain Asia.

关键词： Water budget Runoff Freeze-thaw processes Active layer Permafrost basin Alpine wetland

β-双亚胺稀土双烷基配合物催化邻甲氧基苯乙烯高间规聚合研究

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高分子学报 2024年第6期55卷 729-737页

作者：王田田孙碧玮吴春姬崔冬梅中国科学院长春应用化学研究所、高分子物理与化学国家重点实验室长春130022 中国科学技术大学应用化学与工程学院合肥230026

设计合成了一类氮原子上含脂肪族取代基的β-双亚胺的配体及其相应的稀土金属配合物1~3.在助催化剂有机硼盐和烷基铝的作用下,将配合物1~3用于催化邻甲氧基苯乙烯(oMOS)聚合中,制得了高间规选择性(rrrr‍>‍99%)聚合物,所得聚合物的玻璃... 详细信息

设计合成了一类氮原子上含脂肪族取代基的β-双亚胺的配体及其相应的稀土金属配合物1~3.在助催化剂有机硼盐和烷基铝的作用下,将配合物1~3用于催化邻甲氧基苯乙烯(oMOS)聚合中,制得了高间规选择性(rrrr‍>‍99%)聚合物,所得聚合物的玻璃化转变温度Tg为-90℃,熔点Tm为240℃.将配合物2用于催化异戊二烯(IP)均聚合,得到了以1,4-结构为主(含量约88.6%)的聚合物,玻璃化转变温度Tg为-57℃.此外,借助DFT理论计算,发现配位模式是决定邻甲氧基苯乙烯聚合物立体选择性的关键.

关键词：稀土催化剂高间规选择性邻甲氧基聚苯乙烯

Two new lycodine alkaloids from Lycopodiastrum casuarinoides

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Two new lycodine alkaloids from Lycopodiastrum casuarinoides