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Improved ethane conversion to ethylene and aromatics over a Zn/ZSM-5 and CaMnO^(3-δ) composite catalyst

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Journal of Energy Chemistry 2020年第12期29卷 161-166页

作者： Yan Zhang Xia Xu Heqing Jiang Key Laboratory of Biofuels Qingdao Institute of Bioenergy and Bioprocess TechnologyChinese Academy of SciencesQingdao 266101ShandongChina University of Chinese Academy of Sciences Beijing 100049China

Ethane conversion to ethylene and aromatics over Zn/zeolite catalysts is a promising technology for efficient exploitation of light alkanes. However, the reaction faces two major hurdles including the limited ethane conversion due to thermodynamics and the drastic catalyst deactivation by kinetical coke accumulation. Here we present a route to improve ethane conversion using a composite catalyst, involving Zn/HZSM-5 for ethane dehydroaromatization and CaMnO3-δperovskite for in situ selective hydrogen oxidation. The in situ H2 consumption shifts ethane dehydrogenation equilibrium to the desired side and can obviously increase the yield of target product. Furthermore, it is found that the in situ generated H2 O through H2 combustion can significantly suppress the coke formation and consequently enhance the stability of the composite catalyst. After 400 min reaction, a product yield of 23% was retained over the composite catalyst, almost a threefold increase with respect to the Zn/HZSM-5 reference(8%). It is anticipated that this novel composite catalyst combined with an efficient reactor technology may improve the viability of ethane aromatization in utilization.

关键词： Ethane aromatization Composite catalyst Zn/HZSM-5 CaMnO^(3-δ) Hydrogen consumption

Exact mobility edges and topological phase transition in two-dimensional non-Hermitian quasicrystals

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Science China(Physics,Mechanics & Astronomy) 2022年第2期65卷 82-90页

作者： Zhi-Hao xu xu xia Shu Chen Institute of Theoretical Physics and State Key Laboratory of Quantum Optics and Quantum Optics Devices Shanxi UniversityTaiyuan 030006China Beijing National Laboratory for Condensed Matter Physics Institute of PhysicsChinese Academy of SciencesBeijing 100190China Collaborative Innovation Center of Extreme Optics Shanxi UniversityTaiyuan 030006China Chern Institute of Mathematics and LPMC Nankai UniversityTianjin 300071China School of Physical Sciences University of Chinese Academy of SciencesBeijing 100049China Yangtze River Delta Physics Research Center Liyang 213300China

The emergence of the mobility edge(ME)has been recognized as an important characteristic of Anderson localization.The difficulty in understanding the physics of the MEs in three-dimensional(3 D)systems from a microscopic image encourages the development of models in lower-dimensional systems that have exact MEs.While most of the previous studies are concerned with one-dimensional(1 D)quasiperiodic systems,the analytic results that allow for an accurate understanding of two-dimensional(2 D)cases are rare.In this work,we disclose an exactly solvable 2 D quasicrystal model with parity-time(PT)symmetry displaying exact MEs.In the thermodynamic limit,we unveil that the extended-localized transition point,observed at the PT symmetry breaking point,is topologically characterized by a hidden winding number defined in the dual space.The coupling waveguide platform can be used to realize the 2 D non-Hermitian quasicrystal model,and the excitation dynamics can be used to detect the localization features.

关键词： quasicrystals mobility edges non-Hermitian systems localization properties

Assembled Photosensitizers Applied for Enhanced Photodynamic Therapy

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CCS Chemistry 2023年第5期5卷 1043-1060页

作者： Jie Zhao Xia Xu Yang Yang Junbai Li Beijing National Laboratory for Molecular Sciences(BNLMS) CAS Key Lab of ColloidInterface and Chemical ThermodynamicsInstitute of ChemistryChinese Academy of SciencesBeijing 100190 University of Chinese Academy of Sciences Beijing 100049 CAS Key Laboratory for Biomedical Effects of Nanomaterials and Nanosafety National Center for Nanoscience and TechnologyBeijing 100190

Photodynamic therapy(PDT)has emerged as an efficient method for cancer therapy.However,traditional photosensitizers(PSs)always have low bioavailability.For example,hydrophobic PSs tend to aggregate in cells and lead to aggregation-induced quenching;while hydrophilic PSs that have good solubility in water systems can hardly penetrate into cells whose membranes are lipophilic.To overcome these drawbacks,suitable PSs that meet the requirements of PDT are needed.Numerous investigations have been introduced,especially the molecular-assembly technique that can increase the bioavailability of PSs during the tumor therapy process.Besides,increasing the quantum yield of reactive oxygen species(ROS)by adjusting the PS triplet state lifetime as well as developing aggregation-induced emission(AIE)agents can also improve the PDT effect.This review summarizes the molecular-assembly technique to obtain intelligent PSs to achieve high PDT efficiency.First,increasing the quantum yield of ROS by decreasing the energy gap between S_(1)and T_(1)states or increasing the spin–orbit coupling Hamiltonian are introduced.Second,we present the bioavailability of traditional PSs by improving the amphiphilicity of the PSs or using intelligent nanostructures.Then,the AIE PSs that can form ROS in the aggregated state under irradiation are described.Finally,the perspective and challenges of PDT are discussed.

关键词： molecular assembly photosensitizers bioavailability improved therapeutic effect photodynamic therapy

Astrocytic Gap Junctions Contribute to Aberrant Neuronal Synchronization in a Mouse Model of MeCP2 Duplication Syndrome

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Neuroscience Bulletin 2022年第6期38卷 591-606页

作者： Shengnan xia Hua-Tai xu Institute of Neuroscience and State Key Laboratory of Neuroscience CAS Center for Excellence in Brain Science and Intelligence TechnologyChinese Academy of SciencesShanghai 200031China University of Chinese Academy of Seciences Beijing 100049.China Shanghai Center for Brain Science and Brain-Inspired Intelligence Technology Shanghai 201210China

Abnormal synchronous neuronal activity has been widely detected by brain imaging of autistic patients,but its underlying neural mechanism remains unclear.Compared with wild-type mice,our in vivo two-photon imaging showed that transgenic(Tgl)mice over-expressing human autism risk gene MeCP2 exhibited higher neuronal synchrony in the young but lower synchrony in the adult stage.Whole-cell recording of neuronal pairs in brain slices revealed that higher neuronal synchrony in young postnatal Tgl mice was atributed mainly to more prevalent giant slow inward currents(SICs).Both in vivo and slice imaging further demonstrated more dynamic activity and higher synchrony in astrocytes from young Tgl mice.Blocking astrocytic gap junctions markedly decreased the generation of SICs and overall cell synchrony in the Tgl brain.Furthermore,the expression level of Cx43 protein and the coupling efficiency of astrocyte gap junctions remained unchanged in Tgi mice.Thus,astrocytic gap junctions facilitate but do not act as a direct trigger for the abnormal neuronal synchrony in young Tgl mice,revealing the potential role of the astrocyte network in the pathogenesis of MeCP2 duplication syndrome.

关键词： Autism spectrum disorder Astrocyte Gap junction Neuronal synchrony MeCP2-Slow inward current Neuronal development

Structural insights into the Oryza sativa cation transporters HKTs in salt tolerance

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Journal of Integrative Plant Biology 2024年第4期66卷 700-708页

作者： Ran Gao Yutian Jia Xia Xu Peng Fu Jiaqi Zhou Guanghui Yang State Key Laboratory of Plant Environmental Resilience Frontiers Science Center for Molecular Design BreedingCollege of Biological SciencesChina Agricultural UniversityBeijing 100193China

The high-affinity potassium transporters(HKTs),selectively permeable to either Na^(+)alone or Na^(+)/K^(+),play pivotal roles in maintaining plant Na^(+)/K^(+)homeostasis.Although their involvement in salt tolerance is widely reported,the molecular underpinnings of Oryza sativa HKTs remain elusive.In this study,we elucidate the structures of OsHKT1;1 and OsHKT2;1,representing two distinct classes of rice HKTs.The dimeric assembled OsHKTs can be structurally divided into four domains.At the dimer interface,a half-helix or a loop in the third domain is coordinated by the C-terminal region of the opposite subunit.Additionally,we present the structures of OsHKT1;5 salt-tolerant and salt-sensitive variants,a key quantitative trait locus associated with salt tolerance.The salt-tolerant variant of OsHKT1;5 exhibits enhanced Na^(+)transport capability and displays a more flexible conformation.These findings shed light on the molecular basis of rice HKTs and provide insights into their role in salt tolerance.

关键词： HKT salt-tolerant structure

An Optimal Stability Matching Algorithm for DAG Blockchain Based on Matching Theory

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Chinese Journal of Electronics 2021年第2期30卷 367-377页

作者： Xia Xu HUANG Jianhua ZHENG Hong TANG Ruicong East China University of Science and Technology

IOTA is a typical blockchain designed for IoT applications. The Markov chain monte carlo algorithm(MCMC) used in IOTA may lead to a large number of unverified blocks, which increases transaction delay to a certain extent. We propose a Stable matching algorithm(SMA) based on matching theory to stimulate nodes to verify blocks, thereby reducing the number of unverified blocks and the consensus delay. The structure of our Io T blockchain uses the Directed acyc1 ic graph(DAG)to improve the transaction processing capability. The nodes in the network are abstracted as transaction issuers and transaction verifiers. A verification service scheduling system is used to assign transactions to the verifiers and achieve the optimal matching. We designed a trust evaluation mechanism which offers verifiers references and awards to check transactions. The simulation results show that SMA can significantly reduce the number of orphan blocks and improve the transaction throughput, which helps to improve the reliability of the Io T blockchain.

关键词： Blockchain Consensus algorithm Game theory Directed acyc1ic graph (DAG)

Peroxymonosulfate enhanced photoelectrocatalytic oxidation of organic contaminants and simultaneously cathodic recycling of silver

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Journal of Environmental Sciences 2022年第10期34卷 74-83页

作者： Huixin Shao xia Li Juanjuan Zhang xu Zhao Key Laboratory of Drinking Water Science and Technology Research Center for Eco-Environmental SciencesChinese Academy of SciencesBeijing 100085China University of Chinese Academy of Sciences Beijing 100049China State Key Laboratory of Pollution Control and Resources Reuse College of Environmental Science and EngineeringTongji UniversityShanghai 200092China Beijing Capital Co.Ltd. Beijing 100028China

Degradation of organic contaminants with simultaneous recycling of Ag+from silvercontaining organic wastewater such as photographic effluents is desired. Although photoelectrocatalysis(PEC) technology is a good candidate for this type of wastewater, its reaction kinetics still needs to be improved. Herein, peroxymonosulfate(PMS) was employed to enhance the PEC kinetics for oxidation of phenol(PhOH) at the anode and reduction of Ag^(+) at the cathode. The degradation efficiency of phenol(PhOH, 0.1 mmol/L) was increased from 42.8% to 96.9% by adding 5 mmol/L PMS at a potential of 0.25 V. Meanwhile, the Ag(by wt%)deposited on the cathode was 28.1%(Ag_(2)O) in PEC process, while that of Ag(by wt%) was 69.7%(Ag^(0)) by adding PMS. According to the electrochemistry analysis, PMS, as photoelectrons acceptor, enhances the separation efficiency of charges and the direct hoxidation of Ph OH at the photoanode. Meantime, the increasing cathode potential avoided Hevolution and strongly alkaline at the surface of cathode, thus enabling the deposition of Ag+in the form of metallic silver with the help of PMS. In addition, PMS combined with PEC process was effective in treating photographic effluents.

关键词： Peroxymonosulfate Photoelectrocatalysis Organic contaminants degradation Silver recycling Photographic effluents

Distributed Robust Energy and Reserve Dispatch for Coordinated Transmission and Active Distribution Systems

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Journal of Modern Power Systems and Clean Energy 2023年第5期11卷 1494-1506页

作者： Yongli Ji Qingshan xu Yuanxing xia Smart Grid Research Institute Nanjing Institute of TechnologyNanjing 211167China School of Electrical Engineering Southeast UniversityNanjing 210096China

The increasing penetration of renewable energy sources introduces higher requirements for the operation flexibility of transmission system(TS) and connected active distribution systems(DSs). This paper presents an efficient distributed framework for the TS and DSs to work cooperatively yet independently. In addition to conventional power interaction, upward and downward reserve capacities are exchanged to form the feasible access regions at the boundaries that apply to different system operation situations. A distributed robust energy and reserve dispatch approach is proposed under this framework. The approach utilizes the supply-and demand-side resources in different systems to handle various uncertainties and improve overall efficiency and reliability. In particular, integrated as aggregated virtual energy storage(AVES) devices, air-conditioning loads are incorporated into the optimal dispatch. In addition, a reserve model with charging/discharging-state elasticity is developed for AVESs to enhance system flexibility and provide additional reserve support. Different cases are compared to verify the effectiveness and superiority of the proposed approach.

关键词： Air-conditioning load distributed coordination feasible access region interregional energy and reserve support transmission and active distribution system

Risk factors and maternal-fetal outcomes of pregnancies complicated by pre-eclampsia, following cesarean section after a trial vaginal birth

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Chinese Medical Journal 2021年第18期134卷 2249-2251页

作者： Xia Xu Jian-Ying Yan Li-Chun Chen Department of Obstetrics and Gynecology Fujian Maternity and Child Health HospitalAffiliated Hospital of Fujian Medical UniversityFuzhouFujian 350001China

To the Editor:Pre-eclampsia is a leading cause of maternal morbidity and mortality.Although the etiology and progression of pre-eclampsia are not fully understood,it has been demonstrated that delivery is the definitive treatment.The clinician is then faced with the decision of when,and how,to proceed with the delivery.According to the guidelines,pre-eclampsia is not an indication of cesarean section,as expected with some serious complications.This means that pregnant women with pre-eclampsia can have a vaginal trial.However,most pregnant women with pre-eclampsia select to have a direct cesarean section at present.Whether having a cesarean section after trialing a vaginal delivery affects the outcomes of mother and child,and its related risk factors,are still unclear.The purpose of this study was to investigate the risk factors and maternal-neonatal outcomes in severe pre-eclampsia patients who underwent a transfer-cesarean section during vaginal labor.

关键词： vaginal mother fetal