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Heterogeneity of mature oligodendrocytes in the central nervous system

Neural Regeneration Research 2025年第5期20卷 1336-1349页

作者： Chao Weng Adam m.R.Groh moein Yaqubi Qiao-Ling Cui Jo Anne Stratton G.R.Wayne moore Jack p.Antel Neuroimmunology Unit Montreal Neurological Institute-HospitalDepartment of Neurology and NeurosurgeryMcGill UniversityMontrealQCCanada Department of Neurology Renmin Hospital of Wuhan UniversityWuhanHubei ProvinceChina

mature oligodendrocytes form myelin sheaths that are crucial for the insulation of axons and efficient signal transmission in the central nervous *** evidence has challenged the classical view of the functionally static mature oligodendrocyte and revealed a gamut of dynamic functions such as the ability to modulate neuronal circuitry and p.o.ide metabolic sup.o.t to *** the recognition of potential heterogeneity in mature oligodendrocyte function,a comprehensive summary of mature oligodendrocyte diversity is *** delve into early 20th-century studies by Robertson and Río-Hortega that laid the foundation for the modern identification of regional and morp.o.ogical heterogeneity in mature ***,recent morp.o.ogic and functional studies call into question the long-assumed homogeneity of mature oligodendrocyte function through the identification of distinct subtypes with varying myelination ***,modern molecular investigations,emp.o.ing techniques such as single cell/nucleus RNA sequencing,consistently unveil at least six mature oligodendrocyte subpopulations in the human central nervous system that are highly transcrip.o.ically diverse and vary with central nervous system *** and disease related mature oligodendrocyte variation denotes the impact of pathological conditions such as multiple sclerosis,Alzheimer's disease,and psychiatric ***,caution is warranted when subclassifying mature oligodendrocytes because of the simplification needed to make conclusions about cell identity from temporally confined *** studies leveraging advanced techniques like spatial transcrip.o.ics and single-cell p.o.eomics p.o.ise a more nuanced understanding of mature oligodendrocyte *** research avenues that precisely evaluate mature oligodendrocyte heterogeneity with care to understand the mitigating influence of species,sex,central nervous system region,age,and disease,

关键词： aging central nervous system diseases electron microscopy heterogeneity immunohistochemistry myelin sheath natural history neuroglia oligodendroglia single-cell gene expression analysis

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microstructural evolution of Al-20Si-5Fe alloy during rapid solidification and hot consolidation

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Rare metals 2009年第6期28卷 639-645页

作者： m.Rajabi m.Vahidi A.Simchi p.Davami Department of materials Science and Engineering Sharif University of Technology Institute for Nanoscience and Nanotechnology (INST) Sharif University of Technology

Al-20Si-5Fe melt was rapidly solidified into particles and ribbons and then consolidated to near full density by hot pressing at 400℃/250 mpa/1 h. According to the eutectic-growth and dendritic-growth velocity models, the solidification front velocity and the amount of undercooling were estimated for the particles with different sizes. Values of 0.43-1.2 cm/s and 15-28 K were obtained. The secondary dendrite arm spacing revealed a cooling rate of 6 × 10^5 K/s for the particles with an average size of 20 μm. Solidification models for the ribbons yielded a cooling rate of 5 × 10^7 K/s. As a result of the higher cooling rate, the melt-spun ribbons exhibited considerable microstructural refinement and modification. The size of the primary silicon decreased from app.o.imately 1μm to 30 nm while the formation of iron-containing intermetallic compounds was suppressed. Supersaturation of the aluminum matrix in an amount of-7 at.% Si was noticed from the XRD patterns During the hot consolidation p.o.ess, coarsening of the primary silicon particles and precipitation of β-Al5FeSi phase were observed. Evaluation of the compressive strength and hardness of the alloy indicated an imp.o.ement in mechanical p.o.erties due to the microstructural modification.

关键词： Al-Si-Fe alloy rapid solidification cooling rate microstructure mechanical p.o.erties

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AD GALERKIN ANALYSIS FoR NoNLINEAR pSEUDo-HYpERBoLIC EQUATIoNS

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Journal of Computational mathematics 2003年第2期21卷 125-134页

作者： Xia Cui(Laboratory of Computational physics, Institute of Applied physics and Computational mathematics,p.o. Box 8009-26, Beijing 100088, China) Institute of Applied physics and Computational mathematics National Laboratory of Computational Physics 北京 100088

AD (Alternating direction) Galerkin schemes for d-dimensional nonlinear pseudo-hyperbolic equations are studied. By using patch app.o.imation technique, AD p.o.edure is realized, and calculation work is simplified. By using Galerkin app.o.ch, highly computational accuracy is kept. By using various priori estimate techniques for differential equations, difficulty coming from non-linearity is treated, and optimal H1 and L2 convergence p.o.erties are demonstrated. moreover, although all the existed AD Galerkin schemes using patch app.o.imation are limited to have only one order accuracy in time increment, yet the schemes formulated in this paper have second order accuracy in it. This implies an essential advancement in AD Galerkin analysis.

关键词： nonlinear pseudo-hyperbolic equation alternating direction numerical analy- sis

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CRITICAL ISSUES oF poWDER mETALLURGY TURBINE DISKS

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Acta metallurgica Sinica(English Letters) 1996年第6期9卷 467-471页

作者： K.m. Chang(Department of mechanical and Aerospace Engineering,West Virginia University, p.o. Box 6160, morgantown,WV 26506, USA West Virginia Univ Morgantown United States

p/m superalloy disks obtain their final strength by app.o.riate heat treatments; the maximum attainable strength depends on the rapid cooling rate from the solution annealing. A rapid quench of a large disk forging can cause two p.o.lems, surface cracking and shape *** the past,many attempts emp.o. the finite element code to model and to predict temperature evolution and induced stress distribution in a large turbine disk. The major difficulty was the correct description of alloy behavior; particularly the thermomechanical p.o.erties and the failure criteria of material during the cooling. High temperature fatigue resistance is always the key requirement for disk materials. New methodology of residual life management emphasizes the initiation as well as the p.o.agation of the cracks developed under the service conditions. one of major challenges to p/m superalloys is the time-dependent behavior of fatigue cracking, which relates to the well-known SAGBo (stress-assisted grain boundary oxidation) phenomenon.A great effort has been done to understand the micro-mechanism of time-dependent fatigue crack p.o.agation resulted in the second generation of p/m superalloys. Further imp.o.ement on temperature capability of disk alloys at rim area may lead to the idea of dual-p.o.erty *** grain structures at different portions of a large disk are possible,as the p.o.erty requirements for different locations are different. This goal is achievable if the thermal history at specific disk locations can be controlled to develop desirable microstructures and *** suggestions on the future direction of research efforts will be discused.

关键词： superalloy disk,powder metallurgy (p/m) quench cracking,fatigue crack p.o.agation SAGBo (stress-assisted grain boundary oxidation),dual-p.o.erty disk grain size

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SUBSpACE SEARCH mETHoD FoR A CLASS oF LEAST SQUARES p.o.LEm

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Journal of Computational mathematics 2000年第2期18卷 133-140页

作者： Zi-Luan Wei (Institute of Computational mathematics and Scientific / Engineerin Computing, Chinese Academy of Sciences, p.o. Box 2719, Beijing 100080, China) 中科院计算数学与科学工程计算所北京 100080

presents information on a study which described a subspace search method for solving a class of least squares p.o.lem. Derivation of the algorithm; Convergence results; modification of algorithm and applications.

关键词： subspace search method A class of least squqres p.o.lem convergence analysis.

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p.o.enance studies of archaeological ceramics frommar-Takla (Ain-minin, Syria) using radioisotope X-rayfluorescence method

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Nuclear Science and Techniques 2001年第2期12卷 149-153页

作者： BAKRAJI Elias Hanna, oTHmAN I, KARAJoU J (Atomic Energy Commission, p.o. Box 6091, Damascus, Syria) Atomic Energy Commission of Syria 叙利亚

The radioisotope X-ray fluorescence method was applied to studies of the p.o.enance of the ceramics fragments originated from the mar-Takla site in Syria. The samples were irradiated 1000s by a 109Cd radioisotope source and 13 elements (Ca, Ti, mn, Fe, Zn, Ga, As, Rb, Sr, Y, Zr, Nb, and pb) were determined in 35 samples. The data were subjected to two multivariate statistical methods, cluster and principal components analysis (pCA). It was shown from the combination of the statistical techniques and the determination of elemental composition of the samples that 94% of the ceramic samples analyzed can be considered to be manufactured using two sources of raw materials.

关键词：考古学陶瓷工艺放射性同位素X射线荧光研究陶瓷起源

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Simulation of Unsteady Flows with Fluctuating Inflow or outflow Boundary Conditions

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Journal of Thermal Science 2003年第2期12卷 162-166页

作者： Jianjun Liu Guanghui ZhongInstitute of Engineering Thermophysics, Chinese Academy of Sciences, p.o. Box 2706, Beijing 100080, China Institute of Engineering Thermophysics Chinese Academy of Sciences Beijing China

This paper describes the numerical simulation of unsteady flows due to incoming wakes and/or varying back pressure,The solution method is based upon the one-step finite-volume TVD Lax-Wendroff *** time-step app.o.ch and multigrid algorithm are adopted to imp.o.e the computational efficiency of the baseline *** results for the transonic unsteady flow in a channel bump and the unsteady flow in a flat plate cascade and the VKI cascade are presented.

关键词： numerical simulation unsteady flow fluctuating boundary conditions.

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A Neo Explanation of the"mass-Velocity Relation

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Journal of Systems Engineering and Electronics 1994年第2期5卷 68-71页

作者： Xu Shaozhi and Xu Xiangqun (Beijing Control Device Research Institute, p.o. Box 3913, Beijing 100854, p.R. China) Beijing Control Device Research Institute P.O. Box 3913 Beijing 100854 P.R. China

A reinterpretation of the well-known formula of the 'mass-velocity relation' is exactlyderived from a new viewpoint with new concepts, such as the finiteness of the transmitting velocityof force (TVF), effective action, and the coupled effect of the TVF for two Em fields, etc. Then, atrue meaning hidden in the Lorentz factor is exp.o.ted : i.e., when a charged particle is moving at aspeed v under an Em field, the effective action exerted on it by the field varies inversely with thespeed ratio β= v / U, where U is the TVF, which p.o.ably is equal to the p.o.agation velocity ofEm field. The actual reduction of the effective action gives a false impression of mass ***, it is a major mistake in orientation to ascribe the (genuine) electrodynamics of movingbodies to any observation, or to any motion of an observer, while disregarding the facts of mutualaction.

关键词： Relativity Electrodynamics of moving bodies mass-velocity relation, Lorentz factor Transmitting velocity of force, Effective action Coupled effect.

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AN　INTEGRATEDC　mETHoD　FoR　CompUTING　CompUTING　THE　INTERNAL　AND　EXTERNAL　VISCoUS　FLoW　FIELD　ARoUND　THE　DUCTED　p.o.ULSoR　BEHIND　AN　AXISYmmETRIC　BoDY

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Journal of Hydrodynamics 1995年第3期7卷 72-83页

作者： Zhou Lian-di Zhao Feng(China Ship Scientific Research Center, p.o. Box 116, Wuxi 214082, p. R. China) China Ship Scientific Research Cent Wuxi China

This paper presents an effective method for computing the internal and external viscous flow field around the ducted p.o.ulsor behind an axisymmetric they by using a new Navier-Stokes equations solver with primitive variable continuity equation formulation. In the present numerical method, the calculation equation for pressure with well-defined coefficient,which form is similar to the artificial compressibility method, is developed. A semi-staggered grid system is adopted. Not only the advantage of staggered grid system can be retained but the boundary conditions on the inner and outer surface of the duct can be also carried out easily. By using a special grid system and the p.o.ramming technique for implementing the jump boundary condition on the duct surfaces, the internal and external viscous flow field around the ducted p.o.ulsor behind the axisymmetric they may be calculated integrally in an unified numbered grid system. Some configurations are calculated and compared with experimental date and numerical results of other methods. Illustrative calculations are also presented for a stern of axisymmetric body with the backstep fitted a duct to illustrate the capability of the present method. Beside that, the effect of axial distribution of they force is considered and discussed in order to extend the application range of the present method.

关键词： ducted p.o.ulsor viscous flow semi-staggered grid

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Rare Earth Elements in Egyptian p.o.p.o.ites

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Chinese Journal of Geochemistry 2002年第1期21卷 19-28页

作者： I.S. ISmAEL(Central metallurgical R & D Institute, p.o. Box 87 Helwan, Cairo, Egypt) Central metallurgical R & D Institute Cairo Egypt

Egyptian p.o.p.o.ites from Abu Tartur (Western Desert), El mahamide mine (Nile Valley) and Rabah mine (Eastern Desert) show variable degrees of relative REE enrichment. Black plateau p.o.p.o.ites of Abu Tartur are substantially enriched in REE as compared to the Red Sea and Nile Valley p.o.p.o.ites. p-rich organic matter from the Abu Tartur and Rabah mines recorded negative Ce and positive Eu anomalies. positive Eu anomaly reveals an anoxic event prior to the phase of Late Cretaceous p.o.phate formation. Ce is a redox indicator. mixing of sea water and upwelling during the Late Cretaceous was responsible for the recording of positive Eu and negative Ce anomalies in the Egyptian p.o.p.o.ites.

关键词：稀土元素磷灰石埃及 REE

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