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Subnatural-linewidth fluorescent single photons

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Photonics Research 2024年第4期12卷 625-637页

作者： HE-BIN ZHANG GAO-XIANG LI yong-chun liu State Key Laboratory of Low-Dimensional Quantum Physics Department of PhysicsTsinghua UniversityBeijing 100084China Department of Physics Huazhong Normal UniversityWuhan 430079China Frontier Science Center for Quantum Information Beijing 100084China

Subnatural-linewidth single photons are of vital importance in quantum optics and quantum information science.According to previous research, it appears difficult to utilize resonance fluorescence to generate single photons with subnatural linewidth. Here we propose a universally applicable approach to generate fluorescent single photons with subnatural linewidth, which can be implemented based on Λ-shape and similar energy structures.Further, the general condition to obtain fluorescent single photons with subnatural linewidth is revealed.The single-photon linewidth can be easily manipulated over a broad range by external fields, which can be several orders of magnitude smaller than the natural linewidth. Our study can be easily implemented in various physical platforms with current experimental techniques and will significantly facilitate the research on the quantum nature of resonance fluorescence and the technologies in quantum information science.

关键词： quantum utilize optics

Pb induced dislocation defects of PtCo systems: Strain-triggered oxygen reduction reaction for PEMFC

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Nano Research 2024年第4期17卷 2462-2472页

作者： chun Jin Qiheng Wang Jingjun liu Beijing Key Laboratory of Electrochemical Process and Technology for Materials Beijing 100029China Beijing University of Chemical Technology Beijing 100029China

Design and development of advanced electrocatalysts with high performance and low Pt consumption are crucial for reducing the kinetic energy barrier of the cathode oxygen reduction reaction(ORR)and improving the efficiency of proton exchange membrane fuel cells(PEMFC).In this study,we demonstrate a Pb-modulated PtCo system for efficient ORR,in which the inclusion of Pb in ternary alloys induces dislocation defects due to the significant difference in atomic radius.Dislocation-PtCoPb was confirmed to exhibit significantly higher ORR activity and stability in acidic ORR.In practical PEMFC applications,it outperforms the corresponding commercial Pt/C with a mass activity of 0.58 A·mgPt^(-1),making it a promising alternative to state-of-the-art Pt-based catalysts.The combination of experimental results and density functional theory(DFT)calculations offers valuable atomic-level insights into the dislocation structures.Pb with a larger atomic radius is located in the lattice stretching region below the dislocation slip plane,forming a structure similar to a Cottrell atmosphere,which reduces the dislocation energy and puts the system in a lower energy state.The Cottrell atmosphere pins the dislocation structure and stabilizes the ternary alloy.By adjusting the amount of added Pb,a moderate level of dislocation density induces a tuned strain effect,thereby enhancing the electrocatalytic mechanism by optimizing the electronic structure of the alloy surface and the adsorption and desorption of oxygen species.This work provides valuable insights into the design and development of lattice dislocation defect structures to trigger strain effects for improving ORR performance.

关键词： dislocation defect strain effect Pb-modulated oxygen reduction reaction

Relation Between the Eventual Continuity and the E-property for Markov-Feller Semigroups

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Acta Mathematicae Applicatae Sinica 2024年第1期40卷 1-16页

作者： yong liu Zi-yu liu LMAM School of Mathematical SciencePeking UniversityBeijing100871China

We investigate some relations between two kinds of semigroup regularities, namely the e-property and the eventual continuity, both of which contribute to the ergodicity for Markov processes on Polish spaces.More precisely, we prove that for Markov-Feller semigroup in discrete time and stochastically continuous MarkovFeller semigroup in continuous time, if there exists an ergodic measure whose support has a nonempty interior,then the e-property is satisfied on the interior of the support. In particular, it implies that, restricted on the support of each ergodic measure, the e-property and the eventual continuity are equivalent for the discrete-time and the stochastically continuous continuous-time Markov-Feller semigroups.

关键词： Markov-Feller semigroup ergodicity e-property eventual continuity

Effect of post rolling stress on phase transformation behavior of microalloyed dual phase steel

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Journal of Iron and Steel Research(International) 2024年第3期31卷 688-699页

作者： Wen-quan Sun Sheng-yi yong Tie-heng Yuan Ting-song Yang An-rui He Chao liu Rui-chun Guo National Engineering Research Center for Advanced Rolling and Intelligent Manufacturing University of Science and Technology BeijingBeijing 100083China

The slow phase transformation of microalloyed dual phase steel makes the nonuniform stress and temperature fields during the post rolling cooling process have a significant impact on the phase transformation process.Given the relatively slow phase transformation of DP780 steel within the microalloyed dual phase steel series,the influence of stress on the phase transformation behavior of DP780 steel was investigated.To quantify the nonuniform thermal and stress conditions in the steel coil,a thermo-mechanical coupled finite element model of the hot-rolled strip cooling process was established.Based on the simulation data,DP780 steel was chosen as the research material,and Gleeble 3500 thermal simulation equipment was used for experimental validation.The thermal expansion curves were analyzed through regression to establish the dynamic model of DP780 steel phase transformation under stress.Subsequently,metallographic analysis was conducted to determine phase transformation type and grain size of DP780 steel.The results confirmed that the stress promotes the occurrence of semi-diffusion-type bainite transformation.Furthermore,an appropriate level of stress facilitates the growth of bainitic grains,while the increased stress inhibits the growth of ferritic grains.

关键词： Microalloyed dual phase steel Stress Bainitic transformation Grain Finite element method

Relationship Between Short-chain Fatty Acids and Parkinson’s Disease:A Review from Pathology to Clinic

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Neuroscience Bulletin 2024年第4期40卷 500-516页

作者： Wen-Xiang Duan Fen Wang Jun-Yi liu chun-Feng liu Department of Neurology and Clinical Research Center of Neurological Disease The Second Affiliated Hospital of Soochow UniversitySuzhou215004China Department of Neurology Dushu Lake Hospital affiliated to Soochow UniversitySuzhou215125China Jiangsu Key Laboratory of Neuropsychiatric Diseases and Institute of Neuroscience Soochow UniversitySuzhou215123China

Parkinson’s disease(PD)is a complicated neurodegenerative disease,characterized by the accumulation ofα-synuclein(α-syn)in Lewy bodies and neurites,and massive loss of midbrain dopamine neurons.Increasing evidence suggests that gut microbiota and microbial metabolites are involved in the development of PD.Among these,short-chain fatty acids(SCFAs),the most abundant microbial metabolites,have been proven to play a key role in brain-gut communication.In this review,we analyze the role of SCFAs in the pathology of PD from multiple dimensions and summarize the alterations of SCFAs in PD patients as well as their correlation with motor and non-motor symptoms.Future research should focus on further elucidating the role of SCFAs in neuroinflammation,as well as developing novel strategies employing SCFAs and their derivatives to treat PD.

关键词： Parkinson’s disease Short-chain fatty acids Microbial metabolites Brain-gut-microbiota axis

Mechanism and control of nonuniform phase transformation of microalloyed dual-phase steel during cooling process after hot rolling

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Journal of Iron and Steel Research(International) 2024年第2期31卷 428-441页

作者： Wen-quan Sun Sheng-yi yong Tie-heng Yuan Chao liu San-bao Zhou Rui-chun Guo Meng-xia Tang National Engineering Research Center for Advanced Rolling and Intelligent Manufacturing University of Science and Technology BeijingBeijing100083China Strip Production Plant Xichang Steel and Vanadium Corporation of Pangang GroupXichang615000SichuanChina

After cooling in the hot rolling process,the metallographic structure of microalloyed dual-phase steel is nonuniform along the rolling direction,while the thickness fluctuation of microalloyed dual-phase steel with a nonuniform metallographic structure will occur during cold rolling.The mechanism of nonuniform phase transformation of microalloyed dual-phase steels was studied during the cooling process after hot rolling,and the nonuniform phase transformation of microalloyed dual-phase steel was regulated during the cooling process after hot rolling through process optimization.First,the empirical equation of phase transformation temperature was measured by a dilatometer considering thermal expansion.Then,the phase field and temperature field of laminar cooling process were calculated to provide initial boundary conditions for the finite element model.After that,the coupling finite element model of the temperature phase transformation of the strip steel in coiling transportation process was established.The simulation results show that the different thermal contact conditions of the microalloyed dual-phase steel during coil transportation lead to uneven cooling of the coil,which leads to nonuniform transformation of the coil along the rolling direction.In addition,by prolonging the time interval from coiling to unloading,the phenomenon of nonuniform phase transformation of microalloyed dual-phase steel can be effectively controlled.The simulation results are applied to industrial production.The application results show that prolonging the time interval from coiling to unloading can effectively improve the nonuniform phase transformation of microalloyed dual-phase steel in the cooling process after hot rolling.

关键词： Microalloyed dual-phase steel Thickness fluctuation Cooling Heat conduction Nonuniform phase transition Finite element method

Molecular analyses display the increasing diversity of Podostemaceae in China

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Plant Diversity 2024年第3期46卷 421-424页

作者： Zhi-Zhong Li Zhun Xu Shuang Wu Lang-Xing Yuan chun-Yu Zou Yan liu Jian-yong Lin Shi-Chu Liang Key Laboratory of Ecology of Rare and Endangered Species and Environmental Protection(Guangxi Normal University) Ministry of EducationGuilin 541006China Wuhan Botanical Garden Chinese Academy of SciencesWuhan 430074China Sino-Africa Joint Research Center Chinese Academy of SciencesWuhan 430074China Guangxi Association for Science and Technology Nanning 530023China Tropical Crops Genetic Resources Institute Chinese Academy of Tropical Agricultural SciencesHaikou 571101China Guangxi Institute of Botany Chinese Academy of SciencesGuilin 541006China Guangxi Forestry Research Institute Nanning 530028China

Podostemaceae(riverweed family),one of the largest aquatic plant families in the world,comprises about 350 species in 51 genera placed in three subfamilies,Podostemoideae,Weddellinoideae,and Tristichoideae(Koi et al.,2022).Most Podostemaceae genera(~38)are monotypic or oligotypic,with a high level of endemism(Koi et al.,2018,2022).Members of Podostemaceae adhere to rocks in fast-flowing rivers,streams,or waterfalls in the subtropics and tropics(Koi et al.,2018).As an adaptation to fastrunning currents,the morphological structure of river-weeds tends to be extremely reduced,including a loss or reduction of primary shoots or roots(Koi and Kato,2007).The vegetative mass of these plants resembles lichens or bryophytes,and are thus known commonly as“dream bryophytes”(Philbrick and Retana,1998).Podostemaceae plants flower when the water level drops during the dry season.In recent years,anthropogenic factors and climate change have severely affected river weed habitats,decreasing populations of these plants.

关键词： roots season habitat

B cell development and antibody responses in human immune system mice:current status and future perspective

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Science China(Life Sciences) 2024年第4期67卷 645-652页

作者： Tao Zhang Wentao liu yong-Guang Yang Key Laboratory of Organ Regeneration&Transplantation of the Ministry of Education The First Hospital of Jilin UniversityChangchun 130061China National-Local Joint Engineering Laboratory of Animal Models for Human Diseases Jilin UniversityChangchun 130061China International Center of Future Science Jilin UniversityChangchun 130061China

Humanized immune system(HIS)mice have been developed and used as a small surrogate model to study human immune function under normal or disease conditions.Although variations are found between models,most HIS mice show robust human T cell responses.However,there has been unsuccessful in constructing HIS mice that produce high-affinity human antibodies,primarily due to defects in terminal B cell differentiation,antibody affinity maturation,and development of primary follicles and germinal centers.In this review,we elaborate on the current knowledge about and previous attempts to improve human B cell development in HIS mice,and propose a potential strategy for constructing HIS mice with improved humoral immunity by transplantation of human follicular dendritic cells(FDCs)to facilitate the development of secondary follicles.

关键词： humanized immune system mouse humoral immunity germinal center B cell follicular dendritic cell

Predictive factors for percutaneous nephrolithotomy bleeding risks

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Asian Journal of Urology 2024年第1期11卷 105-109页

作者： U Phun Loo chun Hou yong Guan Chou Teh Urology Department Sarawak General HospitalKuchingMalaysia

Objective:This study aimed to identify predictive factors for percutaneous nephrolithotomy(PCNL)bleeding risks.With better risk stratification,bleeding in high-risk patient can be anticipated and facilitates early identification.Methods:A prospective observational study of PCNL performed at our institution was done.All adults with radio-opaque renal stones planned for PCNL were included except those with coagulopathy,planned for additional procedures.Factors including gender,co-morbidities,body mass index,stone burden,puncture site,tract dilatation size,operative position,surgeon's seniority,and operative duration were studied using stepwise multivariate regression analysis to identify the predictive factors associated with higher estimated hemoglobin(Hb)deficiency.Results:Overall,4.86%patients(n=7)received packed cells transfusion.The mean estimated Hb deficiency was 1.3(range 0-6.5)g/dL and the median was 1.0 g/dL.Stepwise multivariate regression analysis revealed that absence of hypertension(p=0.024),puncture site(p=0.027),and operative duration(p=0.023)were significantly associated with higher estimated Hb deficiency.However,the effect sizes are rather small with partial eta-squared of 0.037,0.066,and 0.038,respectively.Observed power obtained was 0.621,0.722,and 0.625,respectively.Other factors studied did not correlate with Hb difference.Conclusion:Hypertension,puncture site,and operative duration have significant impact on estimated Hb deficiency during PCNL.However,the effect size is rather small despite adequate study power obtained.Nonetheless,operative position(supine or prone),puncture number,or tract dilatation size did not correlate with Hb difference.The mainstay of reducing bleeding in PCNL is still meticulous operative technique.Our study findings also suggest that PCNL can be safely done by urology trainees under supervision in suitably selected patient,without increasing risk of bleeding.

关键词： Percutaneous nephrolithotomy Predictive factor Risk factor Bleeding Blood loss