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CO_2 long-term diffusive leakage into biosphere in geological carbon storage

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Chinese Science Bulletin 2014年第28期59卷 3686-3690页

作者： Qin-yi Li qun Chen Xing Zhang Key Laboratory for Thermal Science and Power Engineering of Ministry of Education Department of Engineering MechanicsTsinghua University

Prediction of CO2 leakage into biosphere is very important for risk assessment in geological carbon storage projects. Underground CO2 can be transported into biosphere through short term leakage due to fractures of wellbores or cap rocks, which has been extensively investigated, and long term leakage due to diffusion, which has few relevant studies. This paper presents a diffusive model for CO2 gradual leakage into biosphere during a long period after CO2 injection. First, the paper describes a general diffusive model with long term secondary trapping effects for CO2 fluxes from underground into biosphere. Secondly, a simplified one-dimensional model is presented and solved for the CO2 concentrations in groundwater. The results show that the groundwater CO2 concentration will reach the maximum value at about 50 th year after CO2 injection and then slowly decrease due to secondary trapping ***, the partition coefficient is the dominant parameter for predicting the groundwater CO2 concentration while the convective mass transfer coefficient plays an insignificant role.

关键词： CO2浓度扩散模型生物圈碳储存泄漏地质二氧化碳浓度质量传递系数

Resonance-Enhanced Photon Excitation Spectroscopy of the Even-Parity Autoionizing Rydberg States of Xe

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Chinese Journal of Chemical Physics 2008年第5期21卷 401-406页

作者： Chun-yan Li Ting-ting Wang Jun-feng Zhen qun Zhang yang Chen Hefei National Laboratory for Physical Sciences at Microscale Department of Chemical Physics University of Science and Technology of China Hefei 230026 China

Xenon atoms were produced in their metastable states 5p^56s[3/2]2 and 5p^56s＇[1/2]0 in a pulsed DC discharge in a beam, and subsequently excited to the even-parity autoionizing Rydberg states 5p^5np＇ [3/2] 1,[1/2] 1, and 5p^5nf＇ [5/2] 3 using single photon excitation. The excitation spectra of the even-parity autoionizing resonance series from the metastable 129Xe were obtained by recording the autoionized Xe＋ with time-of-flight ion detection in the photon energy range of 28000-42000 cm-1. A wealth of autoionizing resonances were newly observed, from which more precise and systematic spectroscopic data of the level energies and quantum defects were derived.

关键词： Xe Pulsed DC discharge Resonance-enhanced photon excitation spectroscopy Autoionizing resonance

n-Butyl Pyridinium Nitrate as a Reusable Ionic Liquid Medium for Knoevenagel Condensation

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Chinese Chemical Letters 2003年第5期14卷 448-450页

作者： yi qun LI Xin Ming XU Mei Yun ZHOU Department of Chemistry Jinan UniversityGuangzhou 510632

The Knoevenagel condensation of carbonyl substrates with active methylene compounds proceeds smoothly with ammonium acetate as catalyst in n-butyl pyridinium nitrate to afford the desired products of good purity in mo... 详细信息

关键词： n-Butyl pyridinium nitrate ionic liquid Knoevenagel condensation.

2-D DOAs estimation in impulsive noise environments using joint diagonalization fractional lower-order spatio-temporal matrices

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Science in China(Series F) 2008年第10期51卷 1585-1593页

作者： XIA TieQi WAN qun WANG XueGang ZHENG yi College of Electronic Engineering University of Electronic Science and Technology of China Chengdu 610054 China

A novel joint diagonalization fractional lower-order spatio-temporal （ST） moments DOA matrix method is proposed to estimate the 2-D DOAs of uncorrelated narrowband signals in the presence of impulsive noise. The new method retains the advantage of the original ST-DOA matrix method which can estimate 2-D DOAs with neither peak searching nor pair matching. Moreover, it can handle sources with common 1-D angles. Simulation results show that the proposed method yields to better performance to restrain the strong impulsive noise than ST-DOA matrix method, especially for low signal-to-noise ratio case.

关键词： DOA fractional lower-order moment impulsive noise joint diagonalization

Joint diagonalization DOA matrix method

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Science in China(Series F) 2008年第9期51卷 1340-1348页

作者： XIA TieQi WANG XueGang ZHENG yi WAN qun College of Electronic Engineering University of Electronic Science and Technology of China Chengdu610054 China

A novel joint diagonalization （DOA） matrix method is proposed to estimate the two-dimensional （2-D） DOAs of uncorrelated narrowband signals. The method constructs three subarrays by exploiting the special structure of the array, thereby obtaining the 2-D DOAs of the array based on joint diagonalization directly with neither peak search nor pair matching. The new method can handle sources with common 1-D angles. Simulation results show the effectiveness of the method.

关键词： antenna array DOA joint diagonalization pair matching

Continuous mechanical tuning of plasmonic nanoassemblies for tunable and selective SERS platforms

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Nano Research 2021年第1期14卷 275-284页

作者： Xiunan yan Qing Chen qun Song Ziyu Huo Ning Zhang Mingming Ma CAS Key Laboratory of Soft Matter Chemistry Hefei National Laboratory for Physical Sciences at the MicroscaleUniversity of Science and Technology of ChinaHefei 230026China Department of Biological and Environmental Engineering Hefei UniversityHefei 230601China

The continuous tuning of plasmonic nanoassembly's structure is the key to manipulate their optical and catalytic ***,we report a strategy of using macroscopic deformation to continuously tune the structure and optical activity of massive plasmonic nanoassemblies that are embedded in elastic polymer *** gold nanoparticles(Au NPs)are assembled to nanochains(Au NCs)with defined length and further embedded into polyvinylpyrrolidone(PVP)*** nanostructure and plasmonic properties of massive Au NCs in this Au NCs-PVP film can be simultaneously and continuously tuned,simply by reversible mechanical deformation of this elastic *** this way,the surface-enhanced Raman scattering(SERS)enhancement factor of this film as a SERS substrate can be mechanically modulated in the range of 10^(0)to 6.8×10^(7).Meanwhile,the PVP matrix also serves as a selective diffusion barrier to eliminate the fluorescence interference of large biomolecules,which enables the Au NCs-PVP film as a convenient SER S substrate for quick and direct analysis of small molecule analytes in biological samples and food,avoiding the complicate and time-consuming sample pretreatment process.

关键词： surface-enhanced Raman scattering(SERS) plasmonic hotspots nanoassembly gold nanoparticles bioanalysis

Modified MUSIC estimation for correlated signals with compressive sampling arrays

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Journal of Systems Engineering and Electronics 2014年第5期25卷 755-760页

作者： yan Jing Naizhang Feng yi Shen School of Astronautics Harbin Institute of Technology School of Information and Electrical Engineering Harbin Institute of Technology in Weihai

This paper addresses the issue of the direction of arrival （DOA） estimation under the compressive sampling （CS） framework. A novel approach, modified multiple signal classification （MMUSIC） based on the CS array （CSA-MMUSIC）, is proposed to resolve the DOA estimation of correlated signals and two closely adjacent signals. By using two random CS matrices, a large size array is compressed into a small size array, which effectively reduces the number of the front end circuit. The theoretical analysis demonstrates that the proposed approach has the advantages of low computational complexity and hardware structure compared to other MMUSIC approaches. Simulation results show that CSAMMUSIC can possess similar angular resolution as MMUSIC.

关键词： direction of arrival (DOA) compressive sampling array (CSA) modified multiple signal classification (MMUSIC) correlated signal.

CO_(2)-Induced Modulation of Si-O Bonds for Low Temperature Plastic Deformation of Amorphous Silica Nanoparticles with Enhanced Photoluminescence

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Energy & Environmental Materials 2024年第4期7卷 404-412页

作者： Kang Huang Wenzhuo Wu Song Xu Pengfei yan Zhongming Wei qun Xu Henan Institute of Advanced Technology Zhengzhou UniversityZhengzhou 450001China College of Materials Science and Engineering Zhengzhou UniversityZhengzhou 450001China State Key Laboratory of Superlattices and Microstructures Institute of Semiconductors Chinese Academy of SciencesBeijing 100083China

Modulation of Si-O bonds under mild conditions has been a challenging issue in the field of material science,which is critical to manufacture highperformance silica-based optical and photonic ***,we introduce a nondestructive technique to achieve Si-O bond rearrangement,leading to plastic deformation and photoluminescence enhancement of amorphous silica nanoparticles using supercritical carbon dioxides in EtOH/H_(2)O solution under mild ***,plastic deformation is achieved by treating hollow mesoporous silica nanospheres using supercritical CO_(2)at 40°C under 20 *** and theoretical studies revealed the critical role of supercritical CO_(2)in the plastic deformation process,which can be intercalated into the hollow mesoporous silica nanospheres with anisotropic stresses and induces the rearrangement of Si-O bonds and transformation of ring *** work suggests a novel approach to engineer high-performance nano-silica glass components for numerous optical and photonic devices under mild condition.

关键词： amorphous silica anisotropic stress photoluminescence plastic deformation supercritical CO_(2)

The critical role of energetic fluctuations in charge separation for efficient molecular doping of organic semiconductors

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Science China Chemistry 2024年第11期67卷 3675-3680页

作者： yan Zeng Guangchao Han Yuanping yi Beijing National Laboratory for Molecular Sciences CAS Key Laboratory of Organic SolidsInstitute of ChemistryChinese Academy of SciencesBeijing 100190China University of Chinese Academy of Sciences Beijing 100049China

Molecular doping is essential to improve the electrical conductivity of organic semiconductors for high-performance organic electronic devices. However, the doping efficiency is influenced by several factors, such as the energy levels, energetic fluctuations, dielectric properties, and molecular packing structures of the doped films, and the underlying mechanisms for highefficiency doping are still unclear. Here, through multi-level theoretical simulations on a series of fullerene derivatives, we identify that the energetic fluctuations can play a decisive role in activating charge separation for molecular doping. In particular,the doping efficiency appears to be exponentially increased with the fluctuation of charge polarization energies. Therefore,although the charge mobility is somewhat decreased, the experimental electrical conductivity is improved with the increased energetic fluctuation. Moreover, it has been found that polarization energy fluctuation can be effectively enhanced by simply introducing side chains with greater flexibility into organic semiconductors. This article paves the way towards high-efficiency molecular doping of organic semiconductors.

关键词： doping efficiency polarization energies energetic fluctuations organic semiconductors