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Digital Earth: decadal experiences and some thoughts

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International Journal of Digital Earth 2010年第1期3卷 31-46页

作者： H.D.Guo z.liu L.W.zhu Center for Earth Observation and Digital Earth Chinese Academy of SciencesNo.9 Beiyitiao RoadZhongguancunHaidian DistrictBeijing 100190China

The understanding that mankind should reasonably exploit and utilize earth resources and effectively protect the planet on which we live,is now widely ***,effective actions can only be conducted if we better understand and visualize the *** meet this need,digital earth science and technology have been put forward and *** paper introduces the evolution and development process of digital earth,and presents an overview by reviewing and analyzing the 1999 and 2009 Beijing Declaration on Digital Earth,the scientific and commercial digital earth systems,global and regional digital earth research,and some existing platforms of digital earth *** also presents some thoughts about digital earth’s future development.

关键词： Beijing Declaration digital earth system global change

Differentiation renders susceptibility to excitotoxicity in HT22 neurons

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Neural Regeneration Research 2013年第14期8卷 1297-1306页

作者： Minchao He Jun liu haowu Cheng Yigang Xing William z Suo Department of Neurology Sun Yat-sen Memorial HospitalSun Yat-sen University Laboratory for Alzheimer's Disease & Aging Research Veterans Affairs Medical Center Department of Neurology University of Kansas Medical Center Molecular & Integrative Physiology University of Kansas Medical Center

HT22 is an immortalized mouse hippocampal neuronal cell line that does not express cholinergic and glutamate receptors like mature hippocampal neurons in vivo. This in part prevents its use as a model for mature hippocampal neurons in memory-related studies. We now report that HT22 cells were appropriately induced to differentiate and possess properties similar to those of mature hippocampal neurons in vivo, such as becoming more glutamate-receptive and excitatory. Results showed that sensitivity of HT22 cells to glutamate-induced toxicity changed dramatically when comparing undifferentiated with differentiated cells, with the half-effective concentration for differentiated cells reducing approximately two orders of magnitude. Moreover, glutamate-induced toxicity in differentiated cells, but not undifferentiated cells, was inhibited by the N-methyi-D- aspartate receptor antagonists Mk-801 and memantine. Evidently, differentiated HT22 cells expressed N-methyI-D-aspartate receptors, while undifferentiated cells did not. Our experimental findings indicated that differentiation is important for immortalized cell lines to render post-mitotic neuronal properties, and that differentiated HT22 neurons represent a better model of hippocampal neurons than undifferentiated cells.

关键词： neural regeneration brain injury HT22 differentiation N-methyI-D-aspartate receptor glutamateexcitatory neurotoxicity mitosis hippocampus neurons Mk-801" memantine grants-supportedpaper neuroregeneration

Designing Electronic Structures of Multiscale Helical Converters for Tailored Ultrabroad Electromagnetic Absorption

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Nano-Micro Letters 2025年第1期17卷 439-455页

作者： zhaobo Feng Chongbo liu Xin Li Guangsheng Luo Naixin zhai Ruizhe Hu Jing Lin Jinbin Peng Yuhui Peng Renchao Che key Laboratory of Jiangxi Province for Persistent Pollutants Control and Resources Recycle School of Environmental and Chemical EngineeringNanchang Hangkong UniversityNanchang 330063People’s Republic of China School of Physics and Materials Nanchang UniversityNanchang 330031People’s Republic of China key Laboratory of Nondestructive Testing Ministry of EducationNanchang Hangkong UniversityNanchang 330063People’s Republic of China Laboratory of Advanced Materials Shanghai Key Lab of Molecular Catalysis and Innovative MaterialsAcademy for Engineering and TechnologyFudan UniversityShanghai 200438People’s Republic of China

Atomic-scale doping strategies and structure design play pivotal roles in tailoring the electronic structure and physicochemical property of electromagnetic wave absorption(EMWA)***,the relationship between configuration and electromagnetic(EM)loss mechanism has remained ***,drawing inspiration from the DNA transcription process,we report the successful synthesis of novel in situ Mn/N co-doped helical carbon nanotubes with ultrabroad EMWA *** calculation and EM simulation confirm that the orbital coupling and spin polarization of the Mn–N4–C configuration,along with cross polarization generated by the helical structure,endow the helical converters with enhanced EM *** a result,HMC-8 demonstrates outstanding EMWA performance,achieving a minimum reflection loss of−63.13 dB at an ultralow thickness of 1.29 *** precise tuning of the graphite domain size,HMC-7 achieves an effective absorption bandwidth(EAB)of 6.08 GHz at 2.02 mm ***,constructing macroscale gradient metamaterials enables an ultrabroadband EAB of 12.16 GHz at a thickness of only 5.00 mm,with the maximum radar cross section reduction value reaching 36.4 dB *** innovative approach not only advances the understanding of metal–nonmetal co-doping but also realizes broadband EMWA,thus contributing to the development of EMWA mechanisms and applications.

关键词： Metal-nonmetal co-doping 3d-2p orbital coupling Spin polarization Helical structure Broadband EM wave absorption

Mechanisms of eutectic lamellar destabilization upon rapid solidification of an undercooled Ag-39.9 at.% Cu eutectic alloy

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Journal of Materials Science & Technology 2020年第24期59卷 173-179页

作者： H.Dong Y.z.Chen z.R.zhang G.B.Shan W.X.zhang F.liu State key Lab.of Solidification Processing Northwestern Polytechnical UniversityXi’an 710072China Yangtze River Delta Research Institute of NPU Taicang 215400China

The eutectic Ag-Cu alloys exhibiting fine Ag-Cu lamellar eutectic structure formed upon rapid solidification have great potentials being used in various engineering ***,the desired fine primary lamellar eutectic structure(PLES)is usually replaced by a coarse anomalous eutectic structure(AES)when the undercooling prior to solidification exceeds a certain *** forming mechanism of AES in the undercooled eutectic Ag-Cu alloy has been a controversial *** this work,the undercooled Ag-39.9 at.% Cu eutectic alloy is solidified under different cooling conditions by using techniques of melt fluxing and copper mold *** results show that the coupled eutectic growth of this alloy undergoes a transition from a slow eutectic-cellular growth(ECG)to a rapid eutectic-dendritic growth(EDG)above a undercooling of 72 k,accompanying with an abrupt change of the distribution and amount of AES in as-solidified *** kinds of primary lamellar eutectic structures are formed by ECG and EDG during recalescence,*** destabilization of PLES that causes the formation of AES is ascribed to two different mechanisms based on the microstructural examination and theoretical *** 72 k,the destabilization of PLES formed by slow ECG is caused by the mechanism of"termination migration"driven by interfacial *** above 72 k,the destabilization of PLES formed by rapid EDG is attributed to the unstable perturbation of interface driven by interfacial energy and solute supersaturation.

关键词： Ag-Cu alloys Rapid solidification Undercooling Eutectics Destabilization

Harmonic balance-based approach for optimal time delay to control unstable periodic orbits of chaotic systems

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Acta Mechanica Sinica 2020年第4期36卷 918-925页

作者： Y.M.Chen Q.X.liu J.k.liu Department of Mechanics Sun Yat-sen UniversityGuangzhou 510275China

As a classical technique for chaos suppression,the time-delayed feedback controlling strategy has been widely developed by stabilizing unstable periodic orbits(UPOs)embedded in chaotic systems.A critical issue for achieving high controlling precision is to search for an appropriate time *** paper proposes a simple yet effective approach,based on incremental harmonic balance method,to determine the optimal time delay in the delayed feedback *** time delay is adjusted within the iterative scheme provided by the proposed method,and finally converges to the period of the target *** long as the optimal time delay is fixed,moreover,the attained solution makes it quite convenient to analyze its stability according to the Floquet theory,which further provides the effective interval of the feedback gain.

关键词： Chaos control Unstable periodic orbit Delayed feedback Optimal time delay Incremental harmonic balance method

Effects of Three-Dimensional Platform Stiffness and Layer Dimensions on Separation of Carcinoma Cells

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Engineering 2021年第10期7卷 1424-1433页

作者： W.G.zhang z.Y.liu S.W.Pang Department of Electrical Engineering Center for BiosystemsNeuroscienceand NanotechnologyCity University of Hong KongHong Kong 999077China

Cancer cell separation is highly desirable for cancer diagnosis and *** biochemical methods,engineered platforms are effective alternatives for sorting carcinoma cells from normal cells based on their unique properties in responding to the physical changes of the surrounding *** this work,three-dimensional(3D)biomimetic scaffold platforms were developed to separate nasopharyngeal carcinoma 43(NPC43)cells from immortalized nasopharyngeal epithelial 460(NP460)cells based on precisely controlled design parameters including stiffness,number of layers,and structural *** migration characteristics of NPC43 and NP460 cells on the scaffold platforms revealed that NPC43 cells could squeeze into 10 lm wide,15 lm deep trenches while NP460 cells could *** different migration behavior was mainly due to cells having different interactions with the surrounding ***43 cells had filopodia-like protrusions,while NP460 cells exhibited a sheet-like *** these 3D biomimetic platforms,89%separation efficiency of NPC43 cells from NP460 cells was achieved on stiffer two-layer scaffold platforms with a 40/10 lm ridge/trench(R/T)grating on the top layer and a 20/10 lm R/T grid on the bottom ***,the separation efficiency was further increased to 93%by adding an active conditioned medium(ACM)that caused the cells to have higher motility and *** results demonstrate the capability to apply biomimetic engineered platforms with appropriate designs to separate cancer cells from normal cells for potential cancer diagnosis and treatment.

关键词： Cell separation Cell migration Nasopharyngeal carcinoma(NPC) 3D scaffold platform

Microstructure and Mechanical Properties of X80 Pipeline Steel Joints by Friction Stir Welding Under Various Cooling Conditions

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Acta Metallurgica Sinica(English Letters) 2020年第1期33卷 88-102页

作者： G.M.Xie R.H.Duan P.Xue z.Y.Ma H.L.liu z.A.Luo State key Laboratory of Rolling and Automation Northeastern UniversityShenyang 110819China Shenyang National Laboratory for Materials Science Institute of Metal ResearchChinese Academy of SciencesShenyang 110016China

X80 pipeline steel plates were friction stir welded(FSW)under air,water,liquid CO2+water,and liquid CO2 cooling conditions,producing defect-free *** microstructural evolution and mechanical properties of these FSW joints were *** granular bainite was observed in the nugget zone(Nz)under air cooling,and lath bainite and lath martensite increased signifi cantly as the cooling medium temperature *** particular,under the liquid CO2 cooling condition,a dual phase structure of lath martensite and fi ne ferrite appeared in the *** to the case under air cooling,a strong shear texture was identifi ed in the Nzs under other rapid cooling conditions,because the partial deformation at elevated temperature was retained through higher cooling *** liquid CO2 cooling,the highest transverse tensile strength and elongation of the joint reached 92%and 82%of those of the basal metal(BM),respectively,due to the weak tempering softening.A maximum impact energy of up to 93%of that of the BM was obtained in the Nz under liquid CO2 cooling,which was attributed to the operation of the dual phase of lath martensite and fi ne ferrite.

关键词： Friction stir welding Pipeline steel Microstructure Mechanical properties Cooling

MECHANICAL STABILIzATION OF DEFORMED AUSTENITEDURING CONTINUOUS COOLING TRANSFORMATION IN AC-Mn-Cr-Ni-Mo PLASTIC DIE STEEL

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Acta Metallurgica Sinica(English Letters) 1998年第2期11卷 93-99页

作者： D.S.liu G.D.Wang X.H.liu G.z.Cui Northeastern Univ Shenyang China

The influence of prior austenite deformed at different temperature on the subsequent continuous cooling bainitic transformation has been investigated in an C-Ma-Cr-Ni-Mo plastic die steel. The results show that the prior deformation in low temperature region of austenite retards significantly the bainitic transformation. For the same continuous cooling schedule, as austenite deformed at lower temperature, the quantity of the classical sheaf-like bainite becomes less. The present results show that severe deformation leads to mechanical stabilization of austenite and causes the difficulty of bainitic ferrite propagation into the austenite.

关键词： plastic die steel deformed austenite continuous cooling bainitic transformation mechanical stabilization of austenite

DAMPING BEHAVIOR OF ULTRAFINE-GRAINED PURE ALUMINUM L2 AND THE DAMPING MECHANISM

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Acta Metallurgica Sinica(English Letters) 2006年第3期19卷 223-227页

作者： z.M. zhang C.J. Xu J.C. Wang H.z. liu School of Materials Science ＆ Engineering Xi＇an University of Technology Xi＇an 710048 Ghina State key Laboratory of Solidification Processing Northwestern Polytechnical University Xi＇an 710072 Ghina

Ultrafine-grained pure aluminum L2 with a mean grain size of 1.01μm was produced by equal channel angular pressing （ECAP） and annealing at 150℃ for 2h. Damping behavior of the alloy was measured using a dynamic mechanical thermal analyzer. The alloy had an excellent damping capacity Q^-1 with the ambient value being 9.8×10^-3 at 1.0Hz when the strain amplitude was 2.0×10^-5. The damping behavior of the alloy showed a non-linear damping variation tendency, that is, with an increase in temperature and a decrease of frequency, the damping capacity of the alloy increased. The damping capacity increased with the strain amplitude when the strain amplitude was less than 4.6×10^-5. When the strain amplitude was higher than 4.6×10^-5, the damping capacity became a constant and independent of strain amplitude. The high damping capacity was attributed to dislocation unpinning and a drag of dislocation on pinning points.

关键词： ECAP ultrafine grain damping capacity aluminum alloy