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Measure Estimates of Nodal Sets of Polyharmonic Functions

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Chinese Annals of Mathematics,Series B 2018年第5期39卷 917-932页

作者： Long tian Department of Applied Mathematics Nanjing University of Science and Technology

This paper deals with the function u which satisfies△k_u = 0, where k≥2 is an integer. Such a function u is called a polyharmonic function. The author gives an upper bound of the measure of the nodal set of u, and s... 详细信息

关键词： Polyharmonic function Nodal set Frequency Measure estimate Growthproperty

Graphdiyne(C_(n)H_(2n-2)based CuI-GDY/ZnAl LDH double S-scheme heterojunction proved with in situ XPS for efficient photocatalytic hydrogen production

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Journal of Materials Science & Technology 2023年第24期155卷 132-141页

作者： tian Wang Zhiliang Jin School of Chemistry and Chemical Engineering Ningxia Key Laboratory of Solar Chemical Conversion TechnologyKey Laboratory for Chemical Engineering and TechnologyState Ethnic Affairs CommissionNorth Minzu UniversityYinchuan 750021China

The photocatalytic performance can be significantly improved by constructing suitable heterojunction *** is well known that graphdiyne possesses a unique conjugated carbon network nanostructure,which gives it ample active sites on its surface and facilitates the reduction of *** this study,a unique new double S-scheme heterojunction photocatalyst was constructed by simple self-assembly of GDY prepared via organic synthesis methods and *** to the study,an internal electric field controlling the transfer direction of the electron hole is formed between the interface of CuI-GDY and ZnAl-LDH,which broadens the light absorption range of the catalyst and improves the redox ability of the photocatalytic ***-GDY and ZnAl-LDH are tightly bound together,which helps to separate the photogenerated carriers while preserving the strong reduction electrons in the GDY conduction band and the strong oxidation holes in the ZnAl-LDH valence band so that they can fully participate in the redox *** charge-transfer paths on the S-scheme heterojunction interface were analyzed by in situ irradiation *** work provides an effective strategy for the construction of double S-scheme heterojunction photocatalysts.

关键词： Conjugated carbon network Graphdiyne S-scheme heterojunction Hydrogen evolution

Occupant Restraint System Simulation and Optimization Based on TESW

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Transactions of Nanjing University of Aeronautics and Astronautics 2016年第2期33卷 224-230页

作者： tian Sheng School of Civil Engineering and Transportation South China University of Technology Guangzhou 510640 P. R. China

Integrated into the development process of a chinese independent brand class sedan,optimization about occupant restraint system associated with dummy chest deceleration is *** on this simulated vehicle deceleration and the target vehicle′s chest deceleration,tipped equivalent square wave(TESW)is calculated by combining the average stiffness kof occupant restraint system and the average free flight time t*from the existant CNCAP(China new car assessment program)tested *** proposing modeling regulations of occupant restraint system and establishing mathematical dynamic modelling(MADYMO)for occupant restraint system of the target vehicle,four optimization design parameters namely vent area A,load limit L,seat belt extension ratio Band pretension force Fare selected by weighted injury criteria(WIC)rule and the first-order response surface *** four parameters have been optimized by using orthogonal test design of four factors with five levels and the optimum combination A5L1B1F5 has been chosen by range and variance *** results show that occupant restraint system performance has been optimized and improved,while meeting the chest deceleration calculation peak based on TESW.

关键词： full frontal impact tipped equivalent square wave occupant restraint system

Innate lymphocytes:pathogenesis and therapeutic targets of liver diseases and cancer

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Cellular & Molecular Immunology 2021年第1期18卷 57-72页

作者： Yongyan Chen Zhigang tian Hefei National Laboratory for Physical Sciences at Microscale the CAS Key Laboratory of Innate Immunity and Chronic DiseaseSchool of Basic Medical SciencesDivision of Life Sciences and MedicineUniversity of Science and Technology of ChinaHefeiChina Institute of Immunology University of Science and Technology of ChinaHefeiChina

The liver is a lymphoid organ with unique immunological properties,particularly,its predominant innate immune *** balance between immune tolerance and immune activity is critical to liver physiological functions and is responsible for the sensitivity of this organ to numerous diseases,including hepatotropic virus infection,alcoholic liver disease,nonalcoholic fatty liver disease,autoimmune liver disease,and liver cancer,which are major health problems *** the past decade,with the discovery of liver-resident natural killer cells,the importance of innate lymphocytes with tissue residency has gradually become the focus of *** this review,we address the current knowledge regarding hepatic innate lymphocytes with unique characteristics,including NK cells,ILC1/2/3s,NKT cells,γδ T cells,and MAIT cells,and their potential roles in liver homeostasis maintenance and the progression of liver diseases and cancer.A better understanding of the immunopathogenesis of hepatic innate lymphocytes will be helpful for proposing effective treatments for liver diseases and cancer.

关键词： Innate lymphocyte Liver disease Liver cancer Innate lymphoid cell Innate-like T lymphocyte

Probing the solar transition region： current status and future perspectives

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Research in Astronomy and Astrophysics 2017年第11期17卷 1-18页

作者： Hui tian School of Earth and Space Sciences Peking University Beijing 100871 China

The solar transition region （TR） is the temperature regime from roughly 0.02 MK to 0.8 MK in the solar atmosphere. It is the transition layer from the collisional and partially ionized chromosphere to the collisionless and fully ionized corona. The TR plays an important role in the mass and energy transport in both the quiet solar atmosphere and solar eruptions. Most of the TR emission lines fall into the spectral range of far ultraviolet and extreme ultraviolet （~400/^-1600/~）. Imaging and spec- troscopic observations in this spectral range are the most important ways to obtain information about the physics of the TR. Static solar atmosphere models predict a very thin TR. However, recent high- resolution observations indicate that the TR is highly dynamic and inhomogeneous. I will summarize some major findings about the TR made through imaging and spectroscopic observations in the past 20 years. These existing observations have demonstrated that the TR may be the key to understanding coronal heating and origin of the solar wind. Future exploration of the solar TR may need to focus on the upper TR, since the plasma in this temperature regime （0.1 MK-0.8 MK） has not been routinely imaged before. High-resolution imaging and spectroscopic observations of the upper TR will not only allow us to track the mass and energy from the lower atmosphere to the corona, but also help us to understand the initiation and heating mechanisms of coronal mass ejections and solar flares.

关键词： Sun: transition region -- Sun: corona -- Sun: flares -- Sun: coronal mass ejections --instrumentation: spectrographs

Recent advances in development of devices and probes for sensing and imaging in the brain

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Science China Chemistry 2021年第6期64卷 915-931页

作者： Zhichao Liu Yang tian Shanghai Key Laboratory of Green Chemistry and Chemical Processes School of Chemistry and Molecular EngineeringEast China Normal UniversityShanghai 200241China

As the most important part of the central nervous system,the brain is extremely complex in structure and *** vivo analysis of chemical signals is an essential way to investigate brain activity and *** functional magnetic resonance imaging(fMRI)or electrophysiology can be used to record brain activity,they are usually limited by low spatiotemporal fidelity or the difficulty of distinguishing the contributions of various *** addition,the development of in vivo biosensors with high selectivity and accuracy is essential to understand the roles that neurochemicals play in the *** this review,we focus on the development of instruments and devices for recording chemical signals in the live ***,the strategies for development of electrochemical and fluorescent probes with high selectivity,high accuracy and good stability are also *** particular,this review highlighted the contributions of our research group to this *** development of techniques and probes enable us to understand the brain structure and function,and the mechanism of brain diseases,providing the solution for preventing and treating brain diseases.

关键词： brain chemistry neurochemicals instruments and devices bioimaging biosensing

Coherent variations of the obliquity components in global ice volume and ocean carbon reservoir over the past 5 Ma

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Science China Earth Sciences 2013年第12期56卷 2160-2172页

作者： tian Jun State Key Laboratory of Marine Geology Tongji University

The Milankovid theory stresses that the summer insolation in the high northern latitudes that is dominated by the precession cycle controls the glacial/interglacial cycles in global climate change. If the climate system responds linearly to the external insolation forcing, the precession cycle of 23 or 19 ka should dominate the variations in the climatic proxy records. I per- formed spectral and evolutive cross spectral analyses on the high resolution benthic ~80 and oa3C records from the South China Sea and the North Atlantic, the proxies of global ice volume and ocean carbon reservoir respectively. I found that the obliquity instead of the eccentricity or the precession is the most marked cycle in the global ice volume and ocean carbon res- ervoir variations over the past 5 Ma. The analysis further reveals that only at the obliquity band instead of the eccentricity or the precession band does the global ice volume and ocean carbon reservoir display consistently high coherency and stable phase relationship over the past 5 Ma. The consistently positive or near-zero phases of the benthic -o^SO relative to the benthic ff3C at the obliquity band suggest that the global carbon cycle is involved in the polar ice sheet growth as an important internal feedback, not a determinative driving factor. The obliquity instead of the precession or the eccentricity takes the dominant role of driving the global climate change during the Pliocene and Pleistocene.

关键词： global ice volume ocean carbon reservoir obliquity 5 Ma

Relationship between δ D and δ18O in precipitation on northand south of the Tibetan Plateau and moisture recycling

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Science China Earth Sciences 2001年第9期44卷 789-807页

作者： tian Lide 1. Laboratory of Ice Core and Cold Regions Environment Cold and Arid Regions Environmental and Engineering Research Institute Chinese Academy of Sciences 730000 Lanzhou China 2. Laboratoire de Modélisation du Climat et de I’Environnement Sur-Yvette 91190 Saclay France

The local meteoric water line (MWL) has been established from north to south of the Tibetan Plateau based on the measured results of δD and δ18O in precipitation and river water, and the relationship between MWL and moisture origins discussed. The spatial and seasonal variations ofd in precipitation and river water on the Tibetan Plateau have been studied. Results show that the spatial and seasonal variations ofd between north and south of the Tanggula Mountains are related to different moisture origins and water recycling.

关键词： Tibetan Plateau MWL deuterium excess

Development of an ultrahard nanotwinned cBN micro tool for cutting hardened steel

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Science China(Technological Sciences) 2016年第6期59卷 876-881页

作者： CHEN Jun Yun JIN tian Ye tian Yong Jun College of Vehicles and Energy Yanshan University College of Mechanical Engineering Yanshan University State Key Laboratory of Metastable Materials Science & Technology Yanshan University

Binderless nanotwinned cubic boron nitride(nt-cBN) synthesized from onion-structured BN precursors under high pressure and high temperature shows a very fine microstructure consisting of densely lamellar nanotwins(average thickness of 4 nm) within nanograins. The unique nanotwinned microstructure offers high hardness, wear resistance, fracture toughness, and thermal stability which are essential for advanced cBN tool materials. Thus, a circular micro tool of nt-cBN was fabricated using femtosecond laser contour machining followed by focused ion beam precision milling. Thereafter turning tests were performed on hardened steel using the studied micro tool. To evaluate the cutting performance, the machined surface quality and subsurface damage of the hardened steel were characterized. The wear mechanism of the nt-cBN micro tool was also investigated. It is found that the fabricated nt-cBN micro tool can generate high quality surface with surface roughness less than 7 nm and nanograin subsurface of about 500 nm deep. In addition, abrasive wear is found to be the dominant wear mechanism of the nt-cBN micro tool in turning hardened steel. These results indicate that nt-cBN has outstanding potential for ultra-precision cutting hardened steel.

关键词： nanotwinned cBN tool fabrication cutting tool micro machining hardened steel