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Phosphine oxide-Sc(OTf)3catalyzed enantioselective bromoaminocyclization of tri-substituted allyl N-tosylcarbamates

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Science China Chemistry 2018年第6期61卷 656-659页

作者： Xiangyu Tan Hongjie pan Hua Tian Yian shi Beijing National Laboratory for Molecular Sciences CAS Key Laboratory of Molecular Recognition and Function Institute of Chemistry Chinese Academy of Sciences Beijing 100190 China University of Chinese Academy of Sciences Beijing 100049 China Institute of Natural and Synthetic Organic Chemistry Changzhou University Changzhou 213164 China Department of Chemistry Colorado State University Fort Collins Colorado 80523 USA

Phosphine oxide-Sc(OTf)3 catalyzed regio-and enantioselective bromoaminocyclization of tri-substituted allyl N-tosylcarbamates is described. Awide variety of optically active tertiary 5-bromo-1,3-oxazinan-2-ones can b... 详细信息

关键词： asymmetric bromonation bromoaminocyclization phosphine oxide-Sc(OTf)3 5-bromo-1,3-oxazinan-2-ones

Sensitivity improvement by Vernier effect in microwave photonic filter based on F-P fiber ring

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Optoelectronics Letters 2025年

作者： LIN Rui ZHANG Ailing CHANG Pengxiang pan Honggang WANG Minghe WANG Bo Engineering Research Center of Optoelectronic Devices & Communication Technology， Ministry of Education， Tianjin Key Laboratory of Film Electronic and Communication Devices， School of Electrical and Electronic Engineering， Tianjin University of Technology

A high sensitivity fiber optic temperature sensor based on Vernier effect in microwave photonic filter based on two paralleled F-P (Fabry-Perot) fiber ring is proposed and experimentally verified. Sensitivity is improved through the Vernier effect， which is caused by two parallel F-P fiber rings with approximate lengths. Temperature interrogation is achieved by monitoring the notch frequency of the superimposed frequency response curve. The temperature sensitivity of -484.514kHz/℃ is achieved in experiment， which is 57 times of the sensor without Vernier effect. The improved sensitivity and simple structure make it have wide potential applications in temperature monitoring of power systems.

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Promotion effects of salt-alkali on ammonia volatilization in a coastal soil

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Pedosphere 2024年第1期34卷 191-199页

作者： Zhenqi shi Dongli SHE Yongchun pan Yongqiu XIA College of Agricultural Science and Engineering Hohai UniversityNanjing 210098China Jiangsu Province Engineering Research Center for Agricultural Soil-Water Efficient Utilization Carbon Sequestration and Emission ReductionNanjing 210098China Key Laboratory of Soil and Sustainable Agriculture Institute of Soil ScienceChinese Academy of SciencesNanjing 210008China

Coastal ecosystems are highly susceptible to salt-related problems due to their formation process and geographical location. As such ecosystems are the most accessible land resources on Earth, clarifying and quantifying the effects of salt-alkali conditions on N concentration and ammonia(NH_(3)) volatilization are pivotal for promoting coastal agricultural productivity. The challenge in establishing this effect is to determine how salt-alkali conditions impact NH_(3) volatilization through direct or indirect interactions. An incubation experiment using a coastal soil from a paddy farmland, combined with the structural equation modeling(SEM) method, was conducted to reveal the net effects of salt-alkali on NH_(3) volatilization and the role of environmental and microbial factors in mutual interaction networks. The specific experimental design consisted of four salt treatments(S1, S2, S3, and S4: 1‰, 3‰, 8‰, and 15‰ NaCl by mass of soil, respectively), four alkaline treatments(A1, A2, A3, and A4: 0.5‰, 1‰, 3‰, and 8‰ NaHCO_(3)by mass of soil, respectively) and a control without NaCl or NaHCO_(3) addition(CK), and each treatment had three urea concentrations(N1, N2, and N3: 0.05, 0.10, and 0.15 g N kg^(-1) soil,respectively) and three replicates. At the N1, N2, and N3 levels, NH_(3)volatilization increased by 9.31%–34.98%, 3.07%–26.92%, and 2.99%–43.61% as the NaCl concentration increased from 1‰ to 15‰, respectively, compared with CK. With an increase in the NaHCO_(3)concentration from 0.5‰ to 8‰, NH_(3) volatilization increased by 8.36%–56.46%, 5.49%–30.10%, and 30.72%–73.18% at the N1, N2, and N3 levels, respectively, compared with CK. According to the SEM method, salinity and alkalinity had positive direct effects on NH_(3)volatilization, with standardized path coefficients of 0.40 and 0.19, *** the total effects(net positive and negative effects) in the SEM results, alkalinity had a greater influence than salinity(total standardized coefficien

关键词： alkalinity coastal ecosystem NH_(3)emission N-transforming microbe salinity structural equation modeling

Macroscopic squeezing in quasi-one-dimensional two-component Bose gases

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Communications in Theoretical Physics 2023年第12期75卷 138-146页

作者： Yaoqi Tian Junqiao pan Tao shi Su Yi CAS Key Laboratory of Theoretical Physics Institute of Theoretical PhysicsChinese Academy of SciencesBeijing 100190China CAS Center for Excellence in Topological Quantum Computation&School of Physical Sciences University of Chinese Academy of SciencesBeijing 100049China Peng Huanwu Collaborative Center for Research and Education Beihang UniversityBeijing 100191China

We investigate the ground-state properties and the dynamics of quasi-one-dimensional quantum droplets of binary Bose condensates by employing the Gaussian state *** show that there exists three quantum phases for the ground states of the droplets,including a coherent state and two macroscopic squeezed *** phase transition between two macroscopic squeezed states is of the third order;while between the macroscopic squeezed state and the coherent is of a crossover *** for the dynamics,we find that,by tuning the reduced scattering length to a negative value,a significant fraction of the atoms can be transferred from a coherent state to a macroscopic squeezed *** studies open up the possibility of generating macroscopic squeezed states using binary condensates.

关键词： Bose-Einstein condensation quantum droplet Bose-Bose mixture Gaussian state

Experiment investigation on visualization and operating characteristics of closed loop plate oscillating heat pipe with parallel channels

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Journal of Central South University 2016年第9期23卷 2410-2418页

作者： shi Wei-xiu pan Li-sheng Department of Energy and Power Engineering Beijing University of Civil Engineering and Architecture Beijing 100044 China Beijing Key Lab of Heating Gas Supply Ventilating and Air Conditioning Engineering Beijing 100044 China State Key Laboratory of High-temperature Gas Dynamics （Institute of Mechanics Chinese Academy of Sciences） Beijing 100190 China

Using ethanol or acetone as the working fluid, visualization of oscillations in steady state was observed visually by high-speed cameras, and temperature oscillating and heat transfer characteristics of closed-loop plate oscillating heat pipe with parallel channels(POHP-PC) were experimentally investigated by varying liquid filled ratios(50%, 70%, 85%), section scales(1 mm×1 mm and 1 mm×1.5 mm), inclination angles, working fluids and heating inputs. It was found that during operating there was mixed flow consisting of plug flow and annular flow in channels of oscillating heat pipe at steady-state. There was an equilibrium position for working fluid of condenser during oscillating, and periodic oscillations occurred up and down in the vicinity of equilibrium position. With heat input increasing, equilibrium position rose slowly as a result of vapor pressure of *** temperature oscillating amplitude possessed a trend of small-large-small and frequency trend was of small-large during steady-state. It may be generally concluded that temperature, whether evaporator or condenser, fluctuated sharply or rose continuously when oscillating heat pipe coming to dry burning state. Simultaneously, it was found that temperature difference of cooling water possibly dropped with heat input rising during dry burning state. Thermal resistance of No. 2 with acetone was lower than that of No. 1 during experiments, but No. 2 achieving heat transfer limit was earlier than No. 1. However, with ethanol, thermal resistance of No. 1 and No. 2 were similar with the heating input less than 110-120 W and filling ratios of 50% and 70%. And with filling ratio of 85%, heating transfer performance of No. 2 was better compared to No. 1 during all the experiments.

关键词： closed loop with parallel channels plate oscillating heat pipe visualization temperature oscillating heat transfer performance filling ratio section scale

NUMERICAL SIMULATION FOR 2D SHALLOW WATER EQUATIONS BY USING GODUNOV-TYPE SCHEME WITH UNSTRUCTURED MESH

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Journal of Hydrodynamics 2006年第4期18卷 475-480页

作者： pan Cun-hong DAI shi-qiang CHEN Sen-mei Shanghai Institute of Applied Mathematics and Mechanics Shanghai University Shanghai 200436 China Zhejiang Institute of Hydraulics and Estuary Hangzhou 310020 China Shanghai Institute of Applied Mathematics and Mechanics Shanghai University. Shanghai 200436 China Zhejiang Institute of Hydraulics and Estuary Hangzhou 310020. China

In order to establish a well-balanced scheme, 2D shallow water equations were transformed and solved by using the Finite Volume Method （FVM） with unstructured mesh. The numerical flux from the interface between cells was computed with an exact Riemann solver, and the improved dry Riemann solver was applied to deal with the wet/dry problems. The model was verified through computing some typical examples and the tidal bore on the Qiantang River. The results show that the scheme is robust and accurate, and could be applied extensively to engineering problems.

关键词： 2D shallow water equations Finite Volume Method (FVM) unstructured mesh Godunov-type scheme Riemann solver

Fluctuation assisted collapses of Bose-Einstein condensates

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Communications in Theoretical Physics 2022年第9期74卷 199-206页

作者： Junqiao pan Yuqi Wang Tao shi Su Yi CAS Key Laboratory of Theoretical Physics Institute of Theoretical PhysicsChinese Academy of SciencesBeijing 100190China School of Physical Sciences University of Chinese Academy of SciencesBeijing 100049China CAS Center for Excellence in Topological Quantum Computation University of Chinese Academy of SciencesBeijing 100049China

We study the collapse dynamics of a Bose-Einstein condensate subjected to a sudden change of the scattering length to a negative value by adopting the self-consistent Gaussian state theory for mixed *** to the Gross-Pitaevskii and the Hartree-Fock-Bogoliubov approaches,both fluctuations and three-body loss are properly treated in our *** find a new type of collapse assisted by fluctuations that amplify the attractive interaction between ***,the calculation of the fluctuated atoms,the entropy,and the second-order correlation function showed that the collapsed gas significantly deviated from a pure state.

关键词： Bose-Einstein condensates collapse fluctuation Hartree-Fock-Bogoliubov formalism

Present-day Upper-crustal Strain Rate Field in Southeastern Tibet and its Geodynamic Implications:Constraints from GPS Measurements with ABIC Method

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Acta Geologica Sinica(English Edition) 2024年第1期98卷 265-275页

作者： YANG Shaohua pan Jiawei LI Haibing shi Yaolin Key Laboratory of Continental Dynamics of Ministry of Natural Resources Institute of GeologyChinese Academy of Geological SciencesBeijing 100037China Jiangsu Donghai Continental Deep Hole Crustal Activity National Observation and Research Station DonghaiJiangsu 222300China Key Laboratory of Computational Geodynamics College of Earth and Planetary SciencesUniversity of Chinese Academy of SciencesBeijing 100049China

The Earth’s surface kinematics and deformation are fundamental to understanding crustal *** effective research approach is to estimate regional motion field and deformation fields based on modern geodetic *** the discrete observed velocity field is obtained,the velocity related fields,such as dilatation rate and maximum shear strain rate,can be estimated by applying varied mathematical *** study applied Akaike's Bayesian Information Criterion(ABIC)method to calculate strain rate fields constrained by GPS observations in the southeast Tibetan *** with results derived from other three methods revealed that our ABIC-derived strain rate fields were more *** maximum shear strain rate highlighted the Xianshuihe–Xiaojiang fault system as the main boundary for the outward migration of material in southeastern Tibet,indicating rotation of eastern Tibet material around the eastern Himalaya rather than whole extrusion along a fixed ***,distinct dilatation rate patterns in the northeast and southwest regions of the fault system were *** northeast region,represented by the Longmenshan area,exhibited negative dilatational anomalies;while the southwest region,represented by the Jinsha River area north of 29°N,displayed positive dilatational *** indicates compression in the former and extension in the *** with deep geophysical observations,we believe that the upper and lower crusts of the Jinsha River area north of 29°N are in an entire expanding state,probably caused by the escape-drag effect of *** presence of a large,low-viscosity region south of 29°N may not enable the entire escape of the crust,but instead result in a differential escape of the lower crust faster than the upper crust.

关键词： strain rate differential escape ABIC GPS southeastern Tibet

Boron removal from metallurgical grade silicon by slag refining based on GA-BP neural network

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Rare Metals 2021年第1期40卷 237-242页

作者： shi-Lai Yuan Hui-Min Lu pan-pan Wang Chen-Guang Tian Zhi-Jiang Gao School of Materials Science and Engineering.Beijing University of Aeronautics and Astronautics Beijing 100191China

In order to investigate the boron removal effect in slag refining process,intermediate frequency furnace was used to purify boron in SiO2-CaO-Na3 AlF6-CaSiO3 slag system at 1,550℃,and back propagation(BP)neural network was used to model the relationship between slag compositions and boron content in SiO2-CaO-Na3 AlF6-CaSiO3 slag *** BP neural network predicted error is below 2.38%.The prediction results show that the slag composition has a significant influence on boron *** the basicity of slag by adding CaO or Na3 AlF6 to CaSiO3-based slag could contribute to the boron removal,and the addition of Na3 AlF6 has a better removal effect in comparison with the addition of *** oxidizing characteristic of CaSiO3 results in the ineffective removal with the addition of *** increase of oxygen potential(pO2)in the CaO-Na3 AlF6-CaSiO3 slag system by varying the SiO2 proportion can also contribute to the boron removal in silicon *** best slag composition to remove boron was predicted by BP neural network using genetic algorithm(GA).The predicted results show that the mass fraction of boron in silicon reduces from 14.0000×10-6 to0.4366×10-6 after slag melting using 23.12%SiO2-10.44%CaO-16.83%Na3 AlF6-49.61%CaSiO3 slag system,close to the experimental boron content in silicon which is below 0.5×10-6.

关键词： Metallurgical grade silicon Boron removal Slag system Genetic algorithm-back propagation neural network