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Spontaneous ferroelectricity in strained low-temperature monoclinic Fe3O4： A first-principles study

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Frontiers of physics 2018年第2期13卷 77-83页

作者： Xiang Liu wen-bo Mi Tianjin Key Laboratory of Low Dimensional Materials Physics and Processing Technology School of Science Tianjin University Tianjin 300354 China

As a single-phase multiferroic material, Fe3O4 exhibits spontaneous ferroelectric polarization below 38 K. However, the nature of the ferroelectricity in Fe3O4and effect of external disturbances such as strain on it remains ambiguous. Here, the spontaneous ferroelectric polarization of low-temperature mon- oclinic Fe3O4 was investigated by first-principles calculations. The pseudo-centrosymmetric FeB42- FEB43 pair has a different valence state. The noncentrosymmetric charge distribution results in fer- roelectric polarization. The initial ferroelectric polarization direction is in the -x and -z directions. The ferroelectricity along the y axis is limited owing to the symmetry of the Cc space group. both the ionic displacement and charge separation at the FeB42-FeB43 pair are affected by strain, which further influences the spontaneous ferroelectric polarization of monoclinic Fe3O4. The ferroelectric polarization along the z axis exhibits an increase of 45.3% as the strain changes from 6% to -6%.

关键词： spontaneous ferroelectric polarization charge ordering biaxial strain Berry phase,modern theory of polarization

WD+RG systems as the progenitors of type Ia supernovae

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Research in Astronomy and Astrophysics 2010年第3期10卷 235-243页

作者： bo Wang Zhan-wen Han National Astronomical Observatories/Yunnan Observatory Chinese Academy of Sciences Kunming 650011 China Graduate University of Chinese Academy of Sciences Beijing 100049 China

Type Ia supernovae （SNe Ia） play an important role in the study of cosmic evolution, especially in cosmology. There are several progenitor models for SNe Ia proposed in the past years. By considering the effect of accretion disk instability on the evolution of white dwarf （WD） binaries, we performed detailed binary evolution calculations for the WD ＋ red-giant （RG） channel of SNe Ia, in which a carbon--oxygen WD accretes material from a RG star to increase its mass to the Chandrasekhar mass limit. According to these calculations, we mapped out the initial and final parameters for SNe Ia in the orbital period-secondary mass （log Pi_ M2^i） plane for various WD masses for this channel. We discussed the influence of the variation of the duty cycle value on the regions for producing SNe Ia. Similar to previous studies, this work also indicates that the long-period dwarf novae offer possible ways for producing SNe Ia. Meanwhile, we find that the surviving companion stars from this channel have a low mass after the SN explosion, which may provide a means for the formation of the population of single low-mass WDs （〈0.45 M⊙）.

关键词： stars: evolution -- supernovae: general -- binaries: close -- white dwarfs

A likely candidate of type Ia supernova progenitors: the X-ray pulsating companion of the hot subdwarf HD 49798

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Research in Astronomy and Astrophysics 2010年第7期10卷 681-688页

作者： bo Wang Zhan-wen Han National Astronomical Observatories / Yunnan Observatory Chinese Academy of Sciences Kunming 650011 China Key Laboratory for the Structure and Evolution of Celestial Objects Chinese Academy of Sciences Kunming 650011 China Graduate University of Chinese Academy of Sciences Beijing 100049 China

HD 49798 is a hydrogen depleted subdwarf 06 star and has an X-ray pulsating companion （RX J0648.0-4418）. The X-ray pulsating companion is a massive white dwarf. Employing Eggleton＇s stellar evolution code with the optically thick wind assumption, we find that the hot subdwarf HD 49798 and its X-ray pulsating companion could produce a type Ia supernova （SN Ia） in future evolution. This implies that the binary system is a likely candidate of an SN Ia progenitor. We also discuss the possibilities of some other WD ＋ He star systems （e.g. V445 Pup and KPD 1930＋2752） for producing SNe Ia.

关键词： binaries close -- stars individual (HD 49798) -- stars evolution -- supernovae general -- white dwarfs

Physical layer security strategies for downlink heterogeneous cloud radio access networks

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The Journal of China Universities of Posts and Telecommunications 2014年第5期21卷 47-54,60页

作者： YAN Shi WANG wen-bo Key Laboratory of Universal Wireless Communication Beijing University of Posts and Telecommunications

Cloud radio access networks （C-RANs） were proposed as promising solutions to increase both spectrum and energy efficiency performance in next generation wireless communication systems. Much works discussed the concrete implementation technology to justify the huge development potential of C-RAN. However, only a few litterateurs focused on characterizing the physical layer security in the downlink. The authors studied the physical layer security in downlink heterogeneous C-RAN systems in the article. To characterize the random deployment of remote radio units （RRUs） with single antenna configuration, the stochastic geometry is based to evaluate the proposals＇ secrecy transmission capacity performances, where the closed-form expressions are derived. Furthermore, two security strategies based on eavesdropper neutralization region to protect the target RRU user against eavesdropping were presented and analyzed. Simulation illustrates the secrecy transmission capacity performance limits on different system parameters. The presented security strategies show a significant enhancement on the secrecy performance.

关键词： C-RAN Poisson point process (PPP) physical layer security heterogeneous

Service behavior modeling and service behavior convergence-based radio resource scheduling in wireless systems

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The Journal of China Universities of Posts and Telecommunications 2011年第4期18卷 52-58,88页

作者： CAI wen-qi ZHANG Xing WANG wen-bo School of Information and Communication Engineering Beijing University of Posts and Telecommunications Beijing 100876 China

With the development of wireless networks, the amount of multiple services increased sharply in recent years. High quality multiple services with low price are urgently needed especially in new generation mobile communication systems, e.g., 3G/LTE networks. It is important to enhance the availability of data service resources. Services have strong association which are used by clients with similar behavior habits in networks. Such feature results in service behavior convergence （SBC） and its utilization will enhance resource efficiency. This paper proposes two applications of service behavior： service prediction and a scheduling algorithm which enhances bandwidth efficiency. Convergence cells are classified according to SBC and hot-spot services are broadcasted separately in each convergence cell. It is demonstrated by stimulation that the bandwidth is saved 80% more than classical cellular system and nearly 20% more than traditional broadcasting system.

关键词： service behavior service prediction improved Apriori algorithm service behavior convergence

Stochastic Variational Inference-Based Parallel and Online Supervised Topic Model for Large-Scale Text Processing

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Journal of Computer Science & Technology 2018年第5期33卷 1007-1022页

作者： Yang Li wen-Zhuo Song bo Yang College of Computer Science and Technology Jilin University Changchun 130012 China Key Laboratory of Symbolic Computation and Knowledge Engineering Ministry of Education Jilin University Changchun 130012 China Aviation University of Air Force Changchun 130062 China

Topic modeling is a mainstream and effective technology to deal with text data, with wide applications in text analysis, natural language, personalized recommendation, computer vision, etc. Among all the known topic models, supervised Latent Dirichlet Allocation （sLDA） is acknowledged as a popular and competitive supervised topic model. How- ever, the gradual increase of the scale of datasets makes sLDA more and more inefficient and time-consuming, and limits its applications in a very narrow range. To solve it, a parallel online sLDA, named PO-sLDA （Parallel and Online sLDA）, is proposed in this study. It uses the stochastic variational inference as the learning method to make the training procedure more rapid and efficient, and a parallel computing mechanism implemented via the MapReduce framework is proposed to promote the capacity of cloud computing and big data processing. The online training capacity supported by PO-sLDA expands the application scope of this approach, making it instrumental for real-life applications with high real-time demand. The validation using two datasets with different sizes shows that the proposed approach has the comparative accuracy as the sLDA and can efficiently accelerate the training procedure. Moreover, its good convergence and online training capacity make it lucrative for the large-scale text data analyzing and processing.

关键词： topic modeling, large-scale text classification, stochastic variational inference, cloud computing online learning

A novel long non-coding RNA, DIR, increases drought tolerance in cassava by modifying stress-related gene expression

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Journal of Integrative Agriculture 2022年第9期21卷 2588-2602页

作者： DONG Shi-man XIAO Liang LI Zhi-bo SHEN Jie YAN Hua-bing LI Shu-xia liao wen-bin PENG Ming Key Laboratory of Biology and Genetic Resources of Tropical Crops Institute of Tropical Bioscience and BiotechnologyChinese Academy of Tropical Agricultural SciencesHaikou 571101P.R.China Key Laboratory for Biology and Genetic Resources of Tropical Crops of Hainan Province Hainan Institute for Tropical Agricultural ResourcesHaikou 571101P.R.China Cash Crops Research Institute Guangxi Academy of Agricultural SciencesNanning 530007P.R.China College of Tropical Crops Hainan UniversityHaikou 570228P.R.China

Cassava is an important tropical cash crop. Severe drought stresses affect cassava productivity and quality, and cause great economic losses in agricultural production. Enhancing the drought tolerance of cassava can effectively improve its yield. Long non-coding RNAs(lncRNAs) are present in a wide variety of eukaryotes. Recently, increasing evidence has shown that lncRNAs play a critical role in the responses to abiotic stresses. However, the function of cassava lncRNAs in the drought response remains largely unknown. In this study, we identified a novel lncRNA, DROUGHT-INDUCED INTERGENIC lncRNA(DIR). Gene expression analysis showed that DIR was significantly induced by drought stress treatment, but did not respond to abscisic acid(ABA) or jasmonic acid(JA) treatments. In addition, overexpression of the DIR gene enhanced proline accumulation and drought tolerance in transgenic cassava. RNA-seq analysis revealed that DIR preferentially affected drought-related genes that were linked to transcription and metabolism. Moreover, RNA pull-down mass spectrometry analysis showed that DIR interacted with 325 proteins. A protein–protein interaction(PPI)analysis found a marked enrichment in proteins associated with the mRNA export and protein quality control ***, these results suggest that DIR and its interacting proteins that regulate mRNA or protein metabolism are involved in mediating the drought stress response. Thus, regulating DIR expression has potential for improving cassava yield under drought conditions.

关键词： lncRNA RNA-seq drought stress cassava DIR

Solvation chemistry of electrolytes for stable anodes of lithium metal batteries

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Nano Research 2023年第6期16卷 8072-8081页

作者： Yaohui Huang bo wen Zhuoliang Jiang Fujun Li Key Laboratory of Advanced Energy Materials Chemistry(Ministry of Education) Renewable Energy Conversion and Storage Center(RECAST)College of ChemistryNankai UniversityTianjin 300071China Haihe Laboratory of Sustainable Chemical Transformations Tianjin 300192China

Lithium metal batteries(LMBs)have gained increasing attention owing to high energy density for large-scale energy storage ***,serious side reactions between Li anodes and organic electrolytes lead to low Columbic efficiency and Li *** progress has been achieved in constructing electrode structures,the interfacial instability of Li anodes is still *** chemistry significantly affects the electrolyte properties and interfacial reactions,but the reaction mechanisms and the roles of each component in electrolytes are still *** review spotlights the recent development of electrolyte regulation with concentration and composition adjustments,aiming to understanding the correlation between solvation structures and Li anode *** perspectives on the solvation design are provided in light of anode interfacial stability in LMBs.

关键词： Li metal batteries solvation structures electrolyte engineering concentration adjustments composition formulations

Enhancement on the ammonia oxidation capacity of ammonia-oxidizing archaeon originated from wastewater:Utilizing low-density static magnetic field

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Frontiers of Environmental Science & Engineering 2021年第5期15卷 67-74页

作者： Zeshen Tian bo Wang Yuyang Li bo Shen Fengjuan Li Xianghua wen State Key Joint Laboratory of Environmental Simulation and Pollution Control School of EnvironmentTsinghua UniversityBeijing100084China

Ammonia-oxidizing archaeon(AOA)could play important roles for nitrogen removal in the bioreactors under conditions such as low pH and low dissolved ***,enhancing ammonia oxidation capability of AOA has great significance for water and wastewater treatment,especially under conditions like low dissolved oxygen *** a novel AOA strain SAT1,which was enriched from a wastewater treatment plant by our group,the effect of magnetic field on AOA’s ammonia oxidation capability,its magnetotaxis and heredity were investigated in this *** with control experiment,AOA’s maximum nitrite-N formation rate during the cultivation increased by 56.8%(0.65 mgN/(L·d))with 20 mT magnetic ***,it was testified that AOA possessed a certain ***,results manifested that the enhancement of AOA’s ammonia oxidation capability was not heritable,that is,lost once the magnetic field was ***,the possible mechanism of improving AOA’s ammonia oxidation capability by magnetic field was owing to the promotion of AOA single cells’growth and fission,rather than the enhancement of their ammonia oxidation *** results shed light on the application of AOA and methods to enhance AOA’s ammonia oxidation capability,especially in wastewater treatment processes under certain conditions.

关键词： Ammonia-oxidizing archaeon Ammonia oxidation Magnetic field Magnetotaxis Heredity