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Constraining the Hubble constant to a precision of about 1% using multi-band dark standard siren detections

Science China(Physics,Mechanics & Astronomy) 2022年第5期65卷 114-140页

作者： Liang-Gui Zhu Ling-Hua Xie Yi-Ming Hu Shuai Liu En-Kun Li Nicola R.Napolitano Bai-tian Tang Jian-Dong Zhang Jianwei Mei School of Physics and Astronomy Sun Yat-sen University(Zhuhai Campus)Zhuhai 519082China moe key laboratory of tian qin mission Tian Qin Research Center for Gravitational PhysicsFrontiers Science Center for Tian QinCNSA Research Center for Gravitational WavesSun Yat-sen University(Zhuhai Campus)Zhuhai 519082China

Gravitational wave signal from the inspiral of stellar-mass binary black hole can be used as standard sirens to perform cosmological *** inspiral covers a wide range of frequency bands,from the millihertz band to the audio-band,allowing for detections by both space-borne and ground-based gravitational wave *** this work,we conduct a comprehensive study on the ability to constrain the Hubble constant using the dark standard sirens,or gravitational wave events that lack electromagnetic *** acquire the redshift information,we weight the galaxies within the localization error box with photometric information from several bands and use them as a proxy for the binary black hole *** discover that tian qin is expected to constrain the Hubble constant to a precision of roughly 30%through detections of 10 gravitational wave events;in the most optimistic case,the Hubble constant can be constrained to a precision oftian qin I+*** the optimistic case,the multi-detector network of tian qin and LISA is capable of constraining the Hubble constant to within 5%*** is worth highlighting that the multi-band network of tian qin and Einstein Telescope is capable of constraining the Hubble constant to a precision of about 1%.We conclude that inferring the Hubble constant without bias from photo-z galaxy catalog is achievable,and we also demonstrate self-consistency using the P-P *** the other hand,high-quality spectroscopic redshift information is crucial for improving the estimation precision of Hubble constant.

关键词： gravitational wave standard siren Hubble constant stellar-mass binary black hole photometric luminosity multi-band gravitational wave detection

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Potential role of tanycyte-derived neurogenesis in Alzheimer's disease

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Neural Regeneration Research 2025年第6期20卷 1599-1612页

作者： Guibo Qi Han Tang Jianian Hu Siying Kang Song qin Department of Anatomy Histologyand EmbryologySchool of Basic Medical SciencesFudan UniversityShanghaiChina State key laboratory of Medical Neurobiology and moe Frontiers Center for Brain Science Fudan UniversityShanghaiChina

Tanycytes, specialized ependymal cells located in the hypothalamus, play a crucial role in the generation of new neurons that contribute to the neural circuits responsible for regulating the systemic energy balance. The precise coordination of the gene networks controlling neurogenesis in naive and mature tanycytes is essential for maintaining homeostasis in adulthood. However, our understanding of the molecular mechanisms and signaling pathways that govern the proliferation and differentiation of tanycytes into neurons remains limited. This article aims to review the recent advancements in research into the mechanisms and functions of tanycyte-derived neurogenesis. Studies employing lineage-tracing techniques have revealed that the neurogenesis specifically originating from tanycytes in the hypothalamus has a compensatory role in neuronal loss and helps maintain energy homeostasis during metabolic diseases. Intriguingly,metabolic disorders are considered early biomarkers of Alzheimer's disease. Furthermore,the neurogenic potential of tanycytes and the state of newborn neurons derived from tanycytes heavily depend on the maintenance of mild microenvironments, which may be disrupted in Alzheimer's disease due to the impaired blood–brain barrier ***, the specific alterations and regulatory mechanisms governing tanycyte-derived neurogenesis in Alzheimer's disease remain unclear. Accumulating evidence suggests that tanycyte-derived neurogenesis might be impaired in Alzheimer's disease, exacerbating neurodegeneration. Confirming this hypothesis, however, poses a challenge because of the lack of long-term tracing and nucleus-specific analyses of newborn neurons in the hypothalamus of patients with Alzheimer's disease. Further research into the molecular mechanisms underlying tanycyte-derived neurogenesis holds promise for identifying small molecules capable of restoring tanycyte proliferation in neurodegenerative diseases. This line of investigation could pro

关键词： Alzheimer's disease blood–brain barrier ependymoglial cells hypothalamus metabolic diseases neural stem cells neurogenesis neuroinflammatory diseases neurons tanycyte

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Detection of astrophysical gravitational wave sources by tianqin and LISA

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Science China(Physics,Mechanics & Astronomy) 2024年第5期67卷 123-163页

作者： Alejandro Torres-Orjuela Shun-Jia Huang Zheng-Cheng Liang Shuai Liu Hai-tian Wang Chang-qing Ye Yi-Ming Hu Jianwei Mei moe key laboratory of tian qin mission Tian Qin Research Center for Gravitational PhysicsSchool of Physics and AstronomyFrontiers Science Center for Tian QinGravitational Wave Research Center of CNSASun Yat-Sen University(Zhuhai Campus)Zhuhai 519082China Department of Physics The University of Hong KongHong Kong 999077China Kavli Institute for Astronomy and Astrophysics Peking UniversityBeijing100871China

tianqin and LISA are space-based laser interferometer gravitational wave(GW)detectors planned to be launched in the *** detectors will detect low-frequency GWs around 10^(-2)Hz;however,tian qin is more sensitive to frequencies above this common sweet-spot while LISA is more sensitive to frequencies below 10^(-2)***,tian qin and LISA will be able to detect the same sources but with different accuracy depending on the source and its *** consider some of the most important astrophysical sources—massive black hole binaries,stellar-mass black hole binaries,double white dwarfs,extreme mass ratio inspirals,light and heavy intermediate mass ratio inspirals,as well as the stochastic gravitational background of astrophysical origin—that tian qin and LISA will be able to *** each of these sources,we analyze how far they can be detected(detection distance)and how well their parameters can be measured(detection accuracy)using a Fisher Matrix *** compare the results obtained by the three detection scenarios(tian qin alone,LISA alone,and joint detection by LISA and tian qin)highlighting the gains from joint detection as well as the contribution of tian qin and LISA to a combined study of astrophysical *** particular,we consider the different orientations,lifetimes,and duty cycles of the two detectors to explore how they can give a more complete picture when working together.

关键词： wave extreme stochastic

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Precision measurement of the Newtonian gravitational constant

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National Science Review 2020年第12期7卷 1803-1817页

作者： Chao Xue Jian-Ping Liu qing Li Jun-Fei Wu Shan-qing Yang Qi Liu Cheng-Gang Shao Liang-Cheng Tu Zhong-Kun Hu Jun Luo tian qin Research Center for Gravitational Physics & School of Physics and Astronomy Sun Yat-sen University(Zhuhai Campus) moe key laboratory of Fundamental Physical Quantities Measurement & Hubei key laboratory of Gravitation and Quantum Physics PGMF and School of PhysicsHuazhong University of Science and Technology

The Newtonian gravitational constant G,which is one of the most important fundamental physical constants in nature,plays a significant role in the fields of theoretical physics,geophysics,astrophysics and *** G was the first physical constant to be introduced in the history of science,it is considered to be one of the most difficult to measure accurately so *** the past two decades,eleven precision measurements of the gravitational constant have been performed,and the latest recommended value for G published by the Committee on Data for Science and Technology(CODATA) is(6.674 08 ±0.000 31) × 10m~3 kgswith a relative uncertainty of 47 parts per *** uncertainty is the smallest compared with previous CODATA recommended values of G;however,it remains a relatively large uncertainty among other fundamental physical *** this paper we briefly review the history of the G measurement,and introduce eleven values of G adopted in CODATA 2014 after 2000 and our latest two values published in 2018 using two independent methods.

关键词： precision measurement Newtonian gravitational constant CODATA

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Analysis of solid-liquid-gas interactions in landfilled municipal solid waste by a bio-hydro-mechanical coupled model

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Science China(Technological Sciences) 2012年第1期55卷 81-89页

作者： CHEN YunMin XU XiaoBing ZHAN LiangTong moe key laboratory of Soft Soils and Geoenvironmental Engineering Zhejiang University Hangzhou 310058 China tian Hua Architecture Planning Engineering Limited Shanghai 200233 China

Based on first-order kinetics of hydrolysis process, biodegradation of municipal solid waste （MSW） is assumed to obey a first-order decay equation which can take the direct effect of water content on biodegradation into account. Hydraulic model is an unsaturated-saturated flow model using mass conservation equations for fluids. Mechanical compression of MSW is ex- pressed by a stress-age coupled compression model. Through above models, a one-dimensional （I-D） bio-hydro-mechanical coupled model is established to analyze solid-liquid-gas interactions in landfilled MSW. Values of all the model parameters for current typical Chinese MSW are determined. Numerical analysis of a hypothetical waste sample in a closed system shows that gas pressure and gas concentration is extremely large which might cause severe gas explosion problem. Total gas production is about 267.0 m3 per wet ton of fresh wastes. For another hypothetical landfilled MSW layer, the coupled model predicts a dis- sipation of gas pressure during passive gas collection process. Annual gas production is large at the beginning of biodegradation, and then decreases with time. Surface settlement of the wastes increases quickly initially and then becomes stable with a compression strain of about 0.32 after 20 years.

关键词： municipal solid waste solid-liquid-gas interaction gas generation settlement

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Reducing surficial and interfacial defects by thiocyanate ionic liquid additive and ammonium formate passivator for efficient and stable perovskite solar cells

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Nano Research 2023年第5期16卷 6849-6858页

作者： Mengfei Zhu Yuren Xia Lina qin Kaiqiang Zhang Junchuan Liang Cheng Zhao Daocheng Hong Minghang Jiang Xinmei Song Jie Wei Pengbo Zhang Yuxi tian Zhong Jin State key laboratory of Coordination Chemistry MOE Key Laboratory of Mesoscopic ChemistryMOE Key Laboratory of High Performance Polymer Materials and TechnologyJiangsu Key Laboratory of Advanced Organic MaterialsSchool of Chemistry and Chemical EngineeringNanjing UniversityNanjingJiangsu 210023China

Organic–inorganic metal halide perovskites have attained extensive attention owing to their outstanding photovoltaic performances,but the existence of numerous defects in crystalline perovskites is still a serious constraint for the further development of perovskite solar cells(PSCs).In particular,the rapid crystallization guided by anti-solvents leads to plenty of surficial and interfacial defects in perovskite ***,we report the adoption of a pseudo-halide anion based ionic liquid additive,1-butyl-3-methylimidazolium thiocyanate(BMIMSCN)for growing ternary cation(CsFAMA,where FA=formamidinium and MA=methylammonium)perovskites with large-scale crystal grains and strong preferential orientation via the enhanced Ostwald ***,a novel halide-free passivator,benzylammonium formate(BAFa),was employed as a buffering layer on the perovskite films to suppress surface-dominated charge *** a result,the cooperative effects of BMIMSCN additive and BAFa passivator lead to significant enhancements on fluorescence lifetime(from 79.41 to 201.01 ns),open-circuit voltage(from 1.13 to 1.19 V),photoelectric conversion efficiency(from 18.90%to 22.33%).Moreover,the BMIMSCN/BAFa-CsFAMA PSCs demonstrated greatly improved stability against moisture and *** work suggests a promising strategy to improve the quality of perovskite materials via reducing the surficial and interfacial defects by the synergistic effects of lattice doping and interface engineering.

关键词： organic–inorganic perovskite solar cells pseudo-halide ion liquid additive non-halide ammonium formate passivator crystalline and interface engineering efficiency and stability improvements

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Optomechanical soft metamaterials

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Acta Mechanica Sinica 2017年第3期33卷 575-584页

作者： Xiangjun Peng Wei He Yifan Liu Fengxian Xin tian Jian Lu State key laboratory for Strength and Vibration of Mechanical Structures Xi'an Jiaotong University moe key laboratory for Multifunctional Materials and Structures Xi'an Jiaotong University

We present a new type of optomechanical soft metamaterials, which is different from conventional mechanical metamaterials, in that they are simple isotropic and homogenous materials without resorting to any complex nano/microstructures. This metamaterial is unique in the sense that its responses to uniaxial forcing can be tailored by programmed laser inputs to manifest different nonlinear constitutive behaviors, such as monotonic, S-shape, plateau, and non-monotonic snapping performance. To demonstrate the novel metamaterial, a thin sheet of soft material impinged by two counterpropagating lasers along its thickness direction and stretched by an in-plane tensile mechanical force is considered. A theoretical model is formulated to characterize the resulting optomechanical behavior of the thin sheet by combining the nonlinear elasticity theory of soft materials and the optical radiation stress theory. The optical radiation stresses predicted by the proposed model are validated by simulations based on the method of finite elements. Programmed optomechanical behaviors are subsequently explored using the validated model under different initial sheet thicknesses and different optical inputs, and the first- and second-order tangential stiffness of the metamaterial are used to plot the phase diagram of its nonlinear constitutive behaviors. The proposed optomechanical soft metamaterial shows great potential in biological medicine, microfluidic manipulation, and other fields.

关键词： Optomechanics Soft metamaterial Optical radiation stress Programmable constitutive relation

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Acoustomechanical constitutive theory for soft materials

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Acta Mechanica Sinica 2016年第5期32卷 828-840页

作者： Fengxian Xin tian Jian Lu State key laboratory for Strength and Vibration of Mechanical Structures Xi’an Jiaotong University moe key laboratory for Multifunctional Materials and Structures Xi’an Jiaotong University

Acoustic wave propagation from surrounding medium into a soft material can generate acoustic radiation stress due to acoustic momentum transfer inside the medium and material, as well as at the interface between the two. To analyze acoustic-induced deformation of soft materials, we establish an acoustomechanical constitutive theory by combining the acoustic radiation stress theory and the nonlinear elasticity theory for soft materials. The acoustic radiation stress tensor is formulated by time averaging the momentum equation of particle motion, which is then introduced into the nonlinear elasticity constitutive relation to construct the acoustomechanical constitutive theory for soft *** a specified case of soft material sheet subjected to two counter-propagating acoustic waves, we demonstrate the nonlinear large deformation of the soft material and analyze the interaction between acoustic waves and material deformation under the conditions of total reflection, acoustic transparency, and acoustic mismatch.

关键词： Acoustomechanical constitutive theory Acoustic radiation stress Soft material

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High-throughput computational material screening of the cycloalkane-based two-dimensional Dion–Jacobson halide perovskites for optoelectronics

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Chinese Physics B 2022年第3期31卷 52-59页

作者： Guoqi Zhao Jiahao Xie Kun Zhou Bangyu Xing Xinjiang Wang Fuyu tian Xin He Lijun Zhang State key laboratory of Integrated Optoelectronics Key Laboratory of Automobile Materials of MOECollege of Materials Science and EngineeringJilin UniversityChangchun 130012China

Two-dimensional(2D) layered perovskites have emerged as potential alternates to traditional three-dimensional(3D)analogs to solve the stability issue of perovskite solar cells. In recent years, many efforts have been spent on manipulating the interlayer organic spacing cation to improve the photovoltaic properties of Dion–Jacobson(DJ) perovskites. In this work, a serious of cycloalkane(CA) molecules were selected as the organic spacing cation in 2D DJ perovskites, which can widely manipulate the optoelectronic properties of the DJ perovskites. The underlying relationship between the CA interlayer molecules and the crystal structures, thermodynamic stabilities, and electronic properties of 58 DJ perovskites has been investigated by using automatic high-throughput workflow cooperated with density-functional(DFT) *** found that these CA-based DJ perovskites are all thermodynamic stable. The sizes of the cycloalkane molecules can influence the degree of inorganic framework distortion and further tune the bandgaps with a wide range of 0.9–2.1 *** findings indicate the cycloalkane molecules are suitable as spacing cation in 2D DJ perovskites and provide a useful guidance in designing novel 2D DJ perovskites for optoelectronic applications.

关键词： first-principle calculations two-dimensional halide perovskites electronic structures Dion–Jacobson phaseperovskites optoelectronic applications

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Sound absorption coefficient optimization of gradient sintered metal fiber felts

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Science China(Technological Sciences) 2016年第5期59卷 699-708页

作者： MENG Han REN Shu Wei XIN Feng Xian LU tian Jian moe key laboratory for Multifunctional Materials and Structures Xi'an Jiaotong University State key laboratory for Strength and Vibration of Mechanical Structures Xi'an Jiaotong University

An optimization method for sound absorption of gradient(multi-layered) sintered metal fiber felts is presented. The theoretical model based on dynamic flow resistivity is selected to calculate the sound absorption coefficient of the sintered metal fiber felts since it only requires three key morphological parameters: fiber diameter, porosity and layer thickness. The model predictions agree well with experimental measurements. Objective functions and constraint conditions are then set up to optimize separately the distribution of porosity, fiber diameter, and simultaneous porosity and fiber diameter in the metal fiber. The optimization problem for either a sole frequency or a pre-specified frequency range is solved using a genetic algorithm method. Acoustic performance comparison between optimized and non-optimized metal fibers is presented to confirm the effectiveness of the optimization method. Gradient sintered metal fiber felts hold great potential for noise control applications particularly when stringent restriction is placed on the total volume and/or weight of sound absorbing material allowed to use.

关键词： sound absorption optimization sintered metal fiber felts

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