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Single cell tells the developmental story

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Science Bulletin 2016年第17期61卷 1355-1357页

作者： Zhengyan Zhan Xin Xu yu.v.Fu State Key Laboratory of Microbial Resources Institute of MicrobiologyChinese Academy of Sciences

Stem cells are undifferentiated cells that retain the ability to self-renew and differentiate into specialized cells,offering a promising resource to generate requisite cell types in regenerative medicine[1,2].Haematopoietic stem cells(HSCs)can differentiate into entire mature blood lineages,sitting at the apex of the haematopoietic hierachy and playing a key role in the long-term maintenance and stabilization of mammalian blood system functions[3,4].HSCs are mostly found in embryo and bone marrow,but also with small amounts in peripheral ***

关键词： maintenance differentiate specialized stabilization embryo mature story retain offering developmental

Ignition Process Evolution at High Supersonic velocities in Channel

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Journal of Thermal Science 2009年第2期18卷 166-172页

作者： M.A.Goldfeldl A.v.Starov K.yu.Timofeev v.A.vinogradov Institute of Theoretical and Applied Mechanics Central Institute of Aviation Motors

The results of experimental research of multi-injector combustors in the regime of the attached pipe are *** a source of high-enthalpy working gas (air), hot shot wind tunnel IT-302M of ITAM, the Siberian Branch ofthe Russian Academy of Sciences was used. Tests have been carried out at Mach numbers 3,4 and 5, in a range ofchange of total temperature from 2000K up to 3000K and static pressure from 0.08MPa up to 0.23MPa. Injectorsection has been manufactured in two versions with a various relative height of wedge-shaped injectors with parallelfuel injection. Influence of conditions on the entrance of the combustion chamber on ignition and a stablecombustion of hydrogen was investigated. Intensive combustion of hydrogen has been received only at Machnumbers 3 and 4. Advantage of injector section with the greater relative height of injectors is revealed. Themechanism of fuel ignition in the combustion chamber of the given configuration was investigated: two-step ignitionprocess including 'kindling' and intensive combustion over all channel volume.

关键词： supersonic combustor ignition stable combustion.

Fermionized Dual vortex Theory for Magnetized Kagome Spin Liquid

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Chinese Physics Letters 2024年第11期41卷 202-207页

作者： Si-yu Pan Gang v.Chen International Center for Quantum Materials School of PhysicsPeking UniversityBeijing 100871China Collaborative Innovation Center of Quantum Matter Beijing 100871China

Inspired by the recent quantum oscillation measurement on the kagome lattice antiferromagnet in finite magnetic fields,we raise the question about the physical contents of the emergent fermions and the gauge fields if the U(1)spin liquid is relevant for the finite-field kagome lattice ***,the magnetic field is non-perturbative in this regime,and the finite-field state has no direct relation with the U(1)Dirac spin liquid proposal at zero *** here consider the fermionized dual vortex liquid state as one possible candidate theory to understand the magnetized kagome spin *** the dual vortex theory,the S^(z) magnetization is the emergent U(1)gauge flux,and the fermionized dual vortex is the emergent *** magnetic field polarizes the spin component that modulates the U(1)gauge flux for the fermionized vortices and generates the quantum *** the mean-field theory,we discuss the gauge field correlation,the vortex–antivortex continuum and the vortex thermal Hall effect.

关键词： oscillation. effect. field.

Dreicer Electric Field Definition and Runaway Electrons in Solar Flares

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Research in Astronomy and Astrophysics 2024年第2期24卷 180-184页

作者： yu.T.Tsap A.v.Stepanov yu.G.Kopylova Crimean Astrophysical Observatory of the Russian Academy of Sciences Nauchny298409Russia Pulkovo Observatory of the Russian Academy of Sciences Pulkovskoje Shosse65/1St.Petersburg196140Russia

We analyze electron acceleration by a large-scale electric field E in a collisional hydrogen plasma under the solar flare coronal conditions based on approaches proposed by Dreicer and Spitzer for the dynamic friction force of *** Dreicer electric field EDr is determined as a critical electric field at which the entire electron population runs *** regimes of strong(E≲E_(Dr))and weak(E≪E_(Dr))electric field are *** is shown that the commonly used formal definition of the Dreicer field leads to an overestimation of its value by about five *** critical velocity at which the electrons of the"tail"of the Maxwell distribution become runaway under the action of the sub-Dreiser electric fields turns out to be underestimated by√3 times in some works because the Coulomb collisions between runaway and thermal electrons are not taken into *** electron acceleration by sub-Dreicer electric fields generated in the solar corona faces difficulties.

关键词： acceleration of particles-Sun flares-Physical Data and Processes

A Model of Irregular Impurity at the Surface of Nanoparticle and Catalytic Activity

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Communications in Theoretical Physics 2012年第7期58卷 55-58页

作者： I.v.Blinova v.v.Gusarov I.yu.Popov St.Petersburg National Research University of Information Technologies Mechanics and OpticsKronverkskiy49St.Petersburg 197101Russia St.Petersburg State Technological Institute (Technical University) Moskovskiy26St.Petersburg 190013Russia

A problem of nanocatalyst improvement is considered. The existence of irregularities at the surface of nanoparticle leads to the increasing of the surface/volume ratio and, correspondingly, to the improvement of the catalytic activity. But this impurity gives one an additional effect due to the change of the electronic density at the surface. We suggest simple model for the description of this effect. The model allows one to find the discrete spectrum of the Schrdinger operator for nanoparticle. Due to this impurity induced bound states the electron density increases near the surface. It leads to the increase of the catalytic activity of nanoparticles with surface impurities.

关键词： semi-infinite crystal operator spectrum impurity catalytic activity nanoparticle

v2551 Cyg:a pulsating star with enigmatic peculiarities

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Research in Astronomy and Astrophysics 2017年第7期17卷 57-66页

作者： Diana P.Kjurkchieva velimir A.Popov Dragomir v.Marchev Kenneth T.Menzies Nikola I.petrov Department of Physics Shumen University IRIDA Observatory Rozhen NAO Tigh Speuran Observatory Institute of Astronomy and NAO Bulgarian Academy of Sciences

Intensive photometric and spectral observations of the variable star v2551 Cyg are *** light curve shape reveals that the target is a pulsating star, contrary to its previous classification as an eclipsing binary. The period and amplitude of the light curve, the amplitudes of color changes and the radial velocity curve of v2551 Cyg are similar to those of a high-amplitude δ Scuti variable. The target seems to pulsate with the fundamental mode. However, v2551 Cyg exhibits several important peculiarities：（i） the decreasing branch of its light curve is steeper than the increasing one;（ii） the radial velocity curve has a flat section in the phase range 0.7-1.2 and short increase of the negative radial velocity at phase 0.7;（iii） the rotational velocity is quite big for a HADS star;（iv） the Fourier coefficients of v2551 Cyg are quite different from those of HADS stars. The target classification is difficult due to these peculiarities.

关键词： stars variables delta Scuti - stars variables RR Lyrae - stars individual (v2551 Cyg)

Evolution of ionization waves in a multi-pulsed plasma jet:the role of memory charges

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Plasma Science and Technology 2023年第3期25卷 95-103页

作者： N yu BABAEvA G v NAIDIS v F TARASENKO D A SOROKIN Cheng ZHANG Tao SHAO Joint Institute for High Temperatures Russian Academy of Sciences Institute of High Current Electronics Siberian BranchRussian Academy of Sciences Institute of Electrical Engineering Chinese Academy of Sciences University of Chinese Academy of Sciences

In this paper,we discuss the properties of ionization waves(IWs)in a multi-pulsed plasma jet while using the two-dimensional computational *** IWs are generated by application of three short negative pulses with a repetition frequency 12.5 *** simulations are performed continuously during a single run while accounting for charges accumulated inside(surface charges)and outside(space charges)the *** plasma forming gas mixture(He/O2=99.8%/0.2%)is injected through the discharge tube into the surrounding humid *** show that an IW can emerge from the tube exit at a pulse rising edge(as a negative IW)and at a falling edge of the same pulse(as a positive IW).It is demonstrated that remnants of the negative and positive charges play an essential role in the discharge *** first pulse travels the shortest distance as it propagates through the initially non-ionized *** IWs developing during the second pulse essentially enlarge the plasma plume *** the same time,the IWs generated by the third pulse eventually decay due to the remnants of charges accumulated during the previous *** memory charges can lead to the IW extinction.

关键词： helium plasma jet multiple pulses positive and negative ionization waves

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中国北方盆地大规模铀成矿作用:地层篇

地质学报 2024年第7期98卷 1953-1976页

作者：程银行金若时 Michel CUNEY v.A.petrov 苗培森中国地质调查局天津地质调查中心(华北地质科技创新中心) 天津300170 中国地质调查局铀矿地质重点实验室天津300170 法国洛林大学资源学院法国NancyF54500 俄罗斯科学院矿床地质、岩石学、矿物学和地球化学研究所俄罗斯Moscow119017

“红黑”耦合沉积建造是中国北方中—新生代盆地(简称北方盆地)砂岩型铀矿的重要控矿要素之一,在勘查实践中得到了广泛证实和应用,指导发现找矿靶区和矿产地300余处,在成矿理论方面取得重要进展。本文系统总结了北方产铀盆地的60万余米... 详细信息

“红黑”耦合沉积建造是中国北方中—新生代盆地(简称北方盆地)砂岩型铀矿的重要控矿要素之一,在勘查实践中得到了广泛证实和应用,指导发现找矿靶区和矿产地300余处,在成矿理论方面取得重要进展。本文系统总结了北方产铀盆地的60万余米铀矿岩芯钻探成果,通过典型矿床赋矿层沉积学、地球化学等对比研究,系统分析了北方盆地侏罗系、白垩系、新近系等赋矿层形成的沉积环境、物质组成等,进一步明确了制约成矿流体运移、铀矿物沉淀的赋矿层条件。结果显示:①北方盆地自侏罗纪以来,发育了Ⅰ中侏罗世—晚侏罗世早期(Bathonian-Oxfordian)、Ⅱ早白垩世早期(valanginian)、Ⅲ早白垩世晚期(Aptian)、Ⅳ晚白垩世早期(Cenomanian)、Ⅴ晚白垩世晚期—早古近纪(Campanian-Thanetian)、Ⅵ早新近纪(Aquitanian-Burdigalian)和Ⅶ晚新近纪(ZancleanPiacenzian)7期红层,与下伏富还原性组分的黑色层构成了典型的对偶沉积建造,为北方盆地大规模成矿奠定了赋矿层基础。②地球化学指标显示:红层中Fe^(2+)/Fe^(3+)比值介于0.29~1.47(n=78),黑层Fe^(2+)/Fe^(3+)比值介于0.57~53.96(n=223),赋矿层Fe^(2+)/Fe^(3+)比值介于1.00~26.45(n=52)。赋矿层、黑层Fe^(2+)/Fe^(3+)比值一般大于1,以发育黄铁矿、炭屑、油斑为特征,为相对较还原的环境。红层Fe^(2+)/Fe^(3+)比值一般小于1,以发育钙质结核为特征,为相对较强氧化的环境。③总有机碳含量显示红层为0~0.16%(n=107),含矿层为0.01%~2.65%(n=137),黑层为0.01%~2.66%(n=339),含矿层总有机碳含量略低于黑层,与铀矿的富集沉淀有密切关系。④砂岩型铀矿体呈“板状”或“楔状”产出于黑层顶部的灰色、灰绿色砂岩和细砂岩,甚至泥岩,红层为含氧含铀流体的运移通道,黑层为含氧含铀流体的富集沉淀的化学屏障。因此,北方盆地红层和黑层对偶沉积、旋回充填是大规模铀成矿必要的地层条件,这些认识打破常规思维,“红黑”旋回叠加导致了北方盆地多层成矿的现象,矿体一般呈板状就位于红层和黑层的过渡带,这对深入理解砂岩型铀矿成矿环境、成矿规律及成矿机理等工作和勘查工作部署具有重要实践意义。

关键词：北方中—新生代盆地砂岩型铀矿大规模成矿沉积环境赋矿层

Electric field distributions along helium plasma jets

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High voltage 2020年第6期5卷 650-653页

作者： George v.Naidis Natalia yu Babaeva Joint Institute for High Temperatures RAS 125412 MoscowRussia

Results of simulations of streamers propagating along the atmospheric-pressure helium plasma jets ejected from a thin tube into ambient air are presented. The computational model includes the equations governing the helium-air mixture composition along and across the jet, as well as the equations, describing streamer propagation in the mixture, for the electric field and the charged species densities. Streamer velocity and spatial-temporal profiles of plasma parameters are obtained for various values of the helium flow rate. It is shown, in agreement with available experimental data, that the electric field values in the heads of streamers increase nearly linearly with the distance from the tube exit and that the slope of this dependence decreases with the growth of the helium flow rate.

关键词： field mixture ambient