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A class of transient acceleration models consistent with Big Bang cosmology

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Research in Astronomy and Astrophysics 2014年第2期14卷 129-138页

作者： Tian-Long Zu jie-wen chen Yang Zhang Key Laboratory for Researches in Galaxies and Cosmology Department of AstronomyUniversity of Science and Technology of China

Is it possible that the current cosmic accelerating expansion will turn into a decelerating one？ Can this transition be realized by some viable theoretical model that is consistent with the standard Big Bang cosmology？ We study a class of phenomeno- logical models with a transient acceleration, based on a dynamical dark energy with a very general form of equation of state Pde = αPde -- βpdem. It mimics the cosmolog- ical constant αde → const for a small scale factor a, and behaves as a barotropic gas with pde → α-3（α＋1） with α 〉 0 for large a. The cosmic evolution of four models in the class has been examined in detail, and all yield a smooth transient acceleration. Depending on the specific model, the future universe may be dominated by either dark energy or by matter. In two models, the dynamical dark energy can be explicitly real- ized by a scalar field with an analytical potential V（O）. Moreover, a statistical analysis shows that the models can be as robust as ACDM in confronting the observational data of Type Ia supernovae, cosmic microwave background （CMB） and baryon acoustic os- cillation. As improvements over previous studies, our models overcome the problem of over-abundance of dark energy during early eras, and satisfy the constraints on dark energy from WMAP observations of CMB.

关键词： cosmology: theory -- methods: analytical

Dual-polarization two-dimensional valley photonic crystals

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Science China(Physics,Mechanics & Astronomy) 2022年第8期65卷 102-109页

作者： Xin-Tao He Jian-Wei Liu Fu-Long Shi Ke Shen wen-jie chen Xiao-Dong chen Jian-wen Dong School of Physics State Key Laboratory of Optoelectronic Materials and TechnologiesSun Yat-sen UniversityGuangzhou510275China

The recent realization of valley physics in photonic systems has enriched the topological phases of light with protected edge modes and shown applications in designing high-performance photonic devices. However, the widely reported valley Hall effect of light in two-dimensional systems is limited to one single polarization. Here, we present dual-polarization two-dimensional valley photonic crystals by simultaneously opening two frequency accidental degenerate Dirac cones. Two band gaps with different polarizations are characterized by opposite-valley Chern numbers, which are confirmed by the opposite-phase vortex distributions of bulk modes and opposite Berry curvatures. This situation results in the polarization-dependent refraction of bulk and edge modes, which locate in opposite valleys. The polarization-independent topological valley transport is also demonstrated. Our work shows the flexible control of light in topological photonic systems with a polarization degree of freedom and has applications in polarization multiplexing photonic devices.

关键词： topological photonics valley photonic crystals polarization

Ideal nodal rings of one-dimensional photonic crystals in the visible region

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Light(Science & Applications) 2022年第6期11卷 1178-1185页

作者： Wei-Min Deng Ze-Ming chen Meng-Yu Li Chao-Heng Guo Zhong-Tao Tian Ke-Xin Sun Xiao-Dong chen wen-jie chen Jian-wen Dong School of Physics&State Key Laboratory of Optoelectronic Materials and Technologies Sun Yat-sen University510275 GuangzhouChina

Three-dimensional(3D)artificial metacrystals host rich topological phases,such as Weyl points,nodal rings,and 3D photonic topological *** topological states enable a wide range of applications,including 3D robust waveguides,one-way fiber,and negative refraction of the surface ***,these carefully designed metacrystals are usually very complex,hindering their extension to nanoscale photonic ***,we theoretically proposed and experimentally realized an ideal nodal ring in the visible region using a simple 1D photonic *** TT-Berrry phase around the ring is manifested by a 2π reflection phase's winding and the resultant drumhead surface *** breaking the inversion symmetry,the nodal ring can be gapped and the n-Berry phase would diffuse into a toroidal-shaped Berry flux,resulting in photonic ridge states(the 3D extension of quantum valley Hall states).Our results provide a simple and feasible platform for exploring 3D topological physics and its potential applications in nanophotonics.

关键词： topological nodal visible

Second Chern crystals with inherently non-trivial topology

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National Science Review 2023年第8期10卷 148-155页

作者： Xiao-Dong chen Fu-Long Shi Jian-Wei Liu Ke Shen Xin-Tao He C.T. Chan wen-jie chen Jian-wen Dong School of Physics and State Key Laboratory of Optoelectronic Materials and Technologies Sun Yat-sen University Department of Physics The Hong Kong University of Science and Technology

Chern insulators have been generalized to many classical wave systems and thereby lead to many potential applications such as robust waveguides, quantum computation and high-performance lasers. However, the band structure of a material can be either topologically trivial or non-trivial, depending on how the crystal structure is designed. Here, we propose a second Chern crystal in a four-dimensional parameter space by introducing two extra synthetic translation dimensions. Since the topology of the bulk bands in the synthetic translation space is intrinsically non-trivial, our proposed four-dimensional crystal is guaranteed to be topologically non-trivial regardless of the crystal’s detailed configuration. We derive the topologically protected modes on the lower dimensional boundaries of such a crystal via dimension ***, we observe the one-dimensional gapless dislocation modes and confirm their robustness in experiments. Our findings provide novel perspectives on topologically non-trivial crystals and may inspire designs of classical wave devices.

关键词： topological photonics synthetic dimension photonic crystals dislocation mode

Exercise combined with administration of adipose-derived stem cells ameliorates neuropathic pain after spinal cord injury

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Neural Regeneration Research 2023年第8期18卷 1841-1846页

作者： Xing cheng Gu-Ping Mao wen-jie Hu Zheng-Ran Yu Yi-Yang Xu Wei chen Xiang Li Xiao-Lin Zeng wen-Wu Zhang jie-wen chen Yong Wan Le Wang Department of Spine Surgery Orthopedic Research InstituteThe First Affiliated Hospital of Sun Yat-sen UniversityGuangdong Provincial Key Laboratory of Orthopedics and TraumatologyGuangzhouGuandong ProvinceChina Department of Joint Surgery and Sport Medicine Orthopedic Research InstituteThe First Affiliated Hospital of Sun Yat-sen UniversityGuangdong Provincial Key Laboratory of Orthopedics and TraumatologyGuangzhouGuandong ProvinceChina Department of Rehabilitation Medicine The Sixth Affiliated Hospital of Sun Yat-sen UniversityGuangzhouGuandong ProvinceChina Department of Spine Surgery Orthopedics Center of Guangdong Provincial People’s Hospital and Guangdong Academy of Medical SciencesGuangzhouGuandong ProvinceChina State Key Laboratory of Ophthalmology Zhongshan Ophthalmic CenterSun Yat-sen UniversityGuangzhouGuandong ProvinceChina

Experimental studies have shown that exercise and human adipose-derived stem cells(ADSCs)play positive roles in spinal cord injury(SCI).However,whether ADSCs and/or exercise have a positive effect on SCI-induced neuropathic pain is still ***,there is a need to explore the effects of exercise combined with administration of ADSCs on neuropathic pain after *** this study,a thoracic 11(T11)SCI contusion model was established in adult C57BL/6 *** was initiated from 7 days post-injury and continued to 28 days post-injury,and approximately 1×105 ADSCs were transplanted into the T11 spinal cord lesion site immediately after *** function and neuropathic pain-related behaviors were assessed weekly using the Basso Mouse Scale,von Frey filament test,Hargreaves method,and cold plate *** studies(Eriochrome cyanine staining and immunohistochemistry)were performed at the end of the experiment(28 days post-injury).Exercise combined with administration of ADSCs partially improved early motor function(7,14,and 21 days postinjury),mechanical allodynia,mechanical hypoalgesia,thermal hyperalgesia,and thermal *** of ADSCs reduced white and gray matter loss at the lesion *** addition,fewer microglia and astrocytes(as identified by expression of ionized calcium-binding adapter molecule 1 and glial fibrillary acidic protein,respectively)were present in the lumbar dorsal horn in the SCI+ADSCs and SCI+exercise+ADSCs groups compared with the sham *** findings suggest that exercise combined with administration of ADSCs is beneficial for the early recovery of motor function and could partially ameliorate SCIinduced neuropathic pain.

关键词： adipose-derived stem cells allodynia exercise glial fibrillary acidic protein hyperalgesia hypoalgesia ionized calcium-binding adapter molecule 1 motor function spinal cord injury

Coalition formation based on a task-oriented collaborative ability vector

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Frontiers of Information Technology & Electronic Engineering 2017年第1期18卷 139-148页

作者： Hao FANG Shao-lei LU jie chen wen-jie chen School of Automation Beijing Institute of Technology State Key Laboratory of Intelligent Control and Decision of Complex Systems

Coalition formation is an important coordination problem in multi-agent systems, and a proper description of collaborative abilities for agents is the basic and key precondition in handling this problem. In this paper, a model of task-oriented collaborative abilities is established, where five task-oriented abilities are extracted to form a collaborative ability vector. A task demand vector is also described. In addition, a method of coalition formation with stochastic mechanism is proposed to reduce excessive competitions. An artificial intelligent algorithm is proposed to compensate for the difference between the expected and actual task requirements, which could improve the cognitive capabilities of agents for human commands. Simulations show the effectiveness of the proposed model and the distributed artificial intelligent algorithm.

关键词： Collaborative vector Task allocation Multi-agent system Coalition formation Artificial intelligence

Rational design and energy catalytic application of high-loading single-atom catalysts

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Rare Metals 2024年第10期43卷 4844-4866页

作者： Zi-Wei Deng Yue Liu jie Lin wen-Xing chen Energy and Catalysis Center School of Materials Science and EngineeringBeijing Institute of Technology Ningbo Institute of Materials Technology and Engineering Chinese Academy of Science

It is well known that single-atom catalysts(SACs)have become a hot topic in the field of catalysis due to their advantages such as 100% metal atom utilization efficiency,high catalytic activity and selectivity compared with conventional catalysts and nanocatalysts. However, the isolated metal atoms on SACs have thermodynamic instability and tend to agglomerate, which limit their catalytic ***, it is of great significance to synthesize stable and high-loading single-atom catalysts(HLSACs). In this paper,we review the research progress of HLSACs from two aspects:design and application. Firstly, we comprehensively introduce the synthesis strategies of HLSACs, namely, top-down and bottom-up methods. Secondly, we overview the application status of HLSACs in three fields: electrocatalysis, thermal catalysis and photocatalysis. Finally, we summarize the development prospects and challenges of HLSACs.

关键词： Design Electrocatalysis High-loading single-atom catalysts Photocatalysis Thermal catalysis

Rapamycin combined with allogenic immature dendritic cells selectively expands CD4^+CD25^+Foxp3^+ regulatory T cells in rats

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Hepatobiliary & Pancreatic Diseases International 2012年第2期11卷 203-208页

作者： Guo-Ying Wang Qi Zhang Yang Yang wen-jie chen Wei Liu Nan Jiang Gui-Hua chen chgh1955@*** Liver Transplantation Center Third Affiliated Hospital Transplantation Research Institute Sun Yat-Sen University Organ Transplantation Research Center of Guangdong Province Guangzhou 510630 China

ReferencesReferencesBackgroundDendritic cells (DCs) can initiate the expansion of regulatory T cells (Tregs), which play an indispensable role in inducing transplantation tolerance. Some studies have investigated the effect of the immunosuppressant rapamycin (Rapa) on Tregs in vitro. However, the in vivo effect of Rapa combined with immature DCs (iDCs) on Tregs is unknown. This study was undertaken to determine whether allogenic iDCs combined with a short course of Rapa have the ability to selectively expand the CD4+CD25+Foxp3+ Tregs in a rat *** Norway rats were injected intravenously with 2×106 Lewis iDCs followed by 1 mg/kg per day Rapa intraperitoneally for 7 consecutive days. On day 8, the levels of CD4+CD25+Foxp3+ Treg cells in peripheral blood and spleen cells were analyzed by flow cytometry. IL-2, IL-4, TGF-β1, and IFN-γ levels in serum were assessed by ELISA. The experimental animals were divided into four groups: control, Rapa-treated, iDC-treated, and ***4+CD25+Foxp3+ Tregs comprised 7%-8%of CD4+ T cells in control rats. Rapa combined with iDCs enhanced this percentage in the peripheral blood and spleen. However, the levels of Tregs did not significantly change after treatment with Rapa or iDCs alone. The levels of CD4+CD25?/sup>Foxp3+ T cells and CD4+ CD25+Foxp3?/sup> T cells in CD4+ T cells did not significantly change in the combined group. The TGF-β1 level in serum from the combined group increased significantly compared with the other *** significantly higher percentage of CD4+ CD25+ Foxp3+ Tregs was found in rats treated with allogenic iDCs and a short course of Rapa, along with an increase in the TGF-β1 level in serum. This improved protocol may be a promising therapeutic strategy to increase Tregs, which are beneficial to the induction of peritransplant tolerance.

关键词： dendritic cells regulatory T cells rapamycin

Quantitative prediction model for the depth limit of oil accumulation in the deep carbonate rocks:A case study of Lower Ordovician in Tazhong area of Tarim Basin

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Petroleum Science 2024年第1期21卷 115-124页

作者： wen-Yang Wang Xiong-Qi Pang Ya-Ping Wang Zhang-Xin chen Fu-jie Jiang Ying chen State Key Laboratory of Lithospheric Evolution Institute of Geology and GeophysicsChinese Academy of SciencesBeijing100029China State Key Laboratory of Petroleum Resources and Prospecting China University of Petroleum(Beijing)Beijing102249China College of Geosciences China University of Petroleum(Beijing)Beijing102249China Research Institute of Exploration and Development PetroChina Southwest Oil&Gas Field CompanyChengdu610041SichuanChina Chemical and Petroleum Engineering Schulich School of EngineeringUniversity of CalgaryCalgaryT2N 1N4Canada

With continuous hydrocarbon exploration extending to deeper basins,the deepest industrial oil accumulation was discovered below 8,200 m,revealing a new exploration ***,the extent to which oil exploration can be extended,and the prediction of the depth limit of oil accumulation(DLOA),are issues that have attracted significant attention in petroleum *** it is difficult to characterize the evolution of the physical properties of the marine carbonate reservoir with burial depth,and the deepest drilling still cannot reach the ***,the DLOA cannot be predicted by directly establishing the relationship between the ratio of drilling to the dry layer and the *** this study,by establishing the relationships between the porosity and the depth and dry layer ratio of the carbonate reservoir,the relationships between the depth and dry layer ratio were obtained *** depth corresponding to a dry layer ratio of 100%is the *** on this,a quantitative prediction model for the DLOA was finally *** results indicate that the porosity of the carbonate reservoir,Lower Ordovician in Tazhong area of Tarim Basin,tends to decrease with burial depth,and manifests as an overall low porosity reservoir in deep *** critical porosity of the DLOA was 1.8%,which is the critical geological condition corresponding to a 100%dry layer ratio encountered in the *** depth of the DLOA was 9,000 *** study provides a new method for DLOA prediction that is beneficial for a deeper understanding of oil accumulation,and is of great importance for scientific guidance on deep oil drilling.

关键词： Deep layer Tarim Basin Hydrocarbon accumulation Depth limit of oil accumulation Prediction model