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RNA methylation preserves ES cell identity by chromatin silencing of retrotransposons

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Signal Transduction and Targeted Therapy 2021年第8期6卷 2259-2260页

作者： Zhaofa Xu Annabel ma Yongchao c.ma Departments of Pediatrics Neurology and PhysiologyNorthwestern University Feinberg School of MedicineAnn&Robert H.Lurie Children’s Hospital of ChicagoChicagoILUSA

RNA methylation on N6-methyladenosine(m6A)and histone methylation are critical mechanisms regulating gene expression at epitranscriptomic and epigenetic levels,***,how RNA methylation modulates histone methylation,and in which biological processes,is *** a recent study published in Nature,Liu et al.1 identified the critical roles of m6A and its reader YTHDc1 in mediating histone methylation and chromatin silencing of retrotransposon genes to preserve embryonic stem(ES)cell identity.

关键词： preserve identity.

Reversed－Phase　High－Performance　Liquid　　chromatographic　Determination　of　Drugs　of　Abuse

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chinese chemical Letters 1996年第11期7卷 1027-1028页

作者： ma, c Duan, HJ Xu, YQ Zhou, TH cHINESE AcAD MED ScI INST MAT MEDBEIJING 100050PEOPLES R CHINA BEIJING UNION MED cOLL BEIJING 100050PEOPLES R CHINA

A high-performance liquid chromatographic method using uv detection for thedetermination of 10 drugs of abuse is described. The method is sample and sensitive. The linear rangesare 20￣100ng/ml with relative standard ... 详细信息

关键词： Determination Drugs Abuse chromatographic

X-ray Multiple Diffraction Topographic Imaging Technique For Growth History Study of Habit Modifying Impurity Doped crystals

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chemical Research in chinese Universities 2004年第4期20卷 411-416页

作者： LAI X. ma c. K. J. Robert M. c. Miller Institute of Particle Science and Engineering Department of Chemical Engineering University of LeedsInstitute of Particle Science and Engineering Department of Chemical Engineering University of LeedsInstitute of Particle Science and Engineering Department of Chemical Engineering University of LeedsCCLRC Daresbury Laboratory Daresbury Leeds LS2 9JT UKLeeds LS2 9JT UKLeeds LS2 9JT UKWarrington Cheshire WA4 4AD UK

A novel crystal characterization instrument has been built up in which a combination of X-ray multiple diffraction and X-ray topography is applied to enabling the cross-correlation between micro-crystallographic symmetry and its spatial dependence in relation to lattice defects. This facility is used to examine, in a self-consistent manner, growth sector-dependant changes to both the crystallographic structure and the lattice defects associated with the action of habit-modifying additives in a number of representative crystal growth systems. In addition, the new instrument can be used to probe micro-crystallographic aspects(such as distortion to crystal symmetry) and relate these in a spatially resolved manner to the crystal defect structure in crystals doped with known habit modifiers.

关键词： X-ray diffraction X-ray multiple diffraction X-ray topography Habit modification crystal growth Growth defects

Influence of wall slip on the hydrodynamic behavior of a two-dimensional slider bearing

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Acta Mechanica Sinica 2007年第6期23卷 655-661页

作者： G. J. ma c. W. Wu P. Zhou State Key Laboratory of Structural Analysis for Industrial Equipment Department of Engineering Mechanics Dalian University of Technology Dalian 116024 China

In the present paper, a multi-linearity method is used to address the nonlinear slip control equation for the hydrodynamic analysis of a two-dimensional （2-D） slip gap flow. Numerical analysis of a finite length slider bearing with wall slip shows that the surface limiting shear stress exerts complicated influences on the hydrodynamic behavior of the gap flow. If the slip occurs at either the stationary surface or the moving surface （especially at the stationary surface）, there is a transition point in the initial limiting shear stress for the proportional coefficient to affect the hydrodynamic load support in two opposite ways： it increases the hydrodynamic load support at higher initial limiting shear stresses, but decreases the hydrodynamic load support at lower initial limiting shear stresses. If the slip occurs at the moving surface only, no fluid pressure is generated in the case of null initial limiting shear stress. If the slip occurs at both the surfaces with the same slip property, the hydrodynamic load support goes off after a critical sliding speed is reached. A small initial limiting shear stress and a small proportionality coefficient always give rise to a low friction drag.

关键词： Wall slip Slider beating Multi-linearity method Quadratic programming

Kinetics of Al Evaporation from Liquid U-Al Alloys in Vacuum Induction Melting

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Journal of materials Science & Technology 2015年第4期31卷 423-426页

作者： Y.J.Duan B.chen Y.c.ma K.Liu materials for Special Environment Division Institute of Metal ResearchChinese Academy of Sciences

A research on kinetics of Al evaporation from liquid U—Al alloys was made in a vacuum induction melting（VIM） furnace at 1673—1843 *** evaporation rate of Al was found to be first order with respect to Al content in the *** overall mass transfer coefficient of Al was determined and it was found that the evaporation rate of Al increased with increasing *** apparent activation energy of Al evaporation at 1673-1843 K was 171.5 kJ *** value of mass transfer coefficient of Al in the liquid phase was estimated to be 3.77 × 10-6,7.41×10-6,and 9.40 × 10-6m s-1at 1673,1753,and 1843 K,***,rate determining steps were discussed and it was concluded that the evaporation rate of Al is mainly controlled by liquid phase mass transfer.

关键词： Al evaporation Kinetics Liquid U-Al alloys mass tr

High-Temperature Oxidation Behavior of a Ni-cr-W-Al Alloy

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Journal of materials Science & Technology 2011年第9期27卷 841-845页

作者： Y.c. ma X.J. Zhao M. Gao K. Liu Institute of Metal Research Chinese Academy of Sciences Shenyang 110016 China

A study was conducted to examine the isothermal oxidation behavior of a new Ni-cr-W-AI alloy in air at 1250℃ with different time. Oxidation kinetics was determined from weight-change measurements. The microstructure and composition of the oxide scale were investigated by means of scanning electron microcopy and X-ray diffraction. The results showed that the oxide scales of the alloy were a compact and continuous outer cr2O3 and Nicr2O4 layer and an inner Al2O3 layer that was in dendrite shape. Oxides scales with good adherence were formed on the surface of the alloy, which made the alloy perform excellent high-temperature oxidation resistance.

关键词： Oxidation kinetics Oxide scale High-temperature oxidation resistance

Determination of Vapor Pressure of Liquid copper by carrier Gas Method

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Journal of materials Science & Technology 2013年第12期29卷 1209-1213页

作者： Y.J.Duan B.chen Y.c.ma M.Gao K.Liu Institute of Metal Research Chinese Academy of Sciences

The relationship between the vapor pressure of liquid copper and the flow rate of carrier gas argon was discussed, when the carrier gas method was used to determine the vapor pressure of liquid copper at 1892 K. The proper argon flow rate range obtained was 150-500 mL/min and enough evidence was provided to verify the vapor pressure-flow rate of carrier gas relationship at the target temperature. Based on the proper flow rate range, the vapor pressure of liquid copper was measured at 1609-1892 K. The relationship of vapor pressure-temperature obtained by the method of regression analysis can be expressed as： In（p/Pa） = （25.470 -I- 0.903） - （39099.8 -4- 1574.5）/T, Further, the thermodynamic properties including the heat of vaporization and the Gibbs free energy of the cu （I） = cu （g） reaction were calculated by the vapor pressiJre obtained over the temperature range covered.

关键词： carrier gas method Liquid copper vapor pressure Thermodynamic property of copper

Solidification pathway and phase transformation behavior in a beta-solidified gamma-TiAl based alloy

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Journal of materials Science & Technology 2019年第11期35卷 2652-2657页

作者： H.Xu X.B.Li W.W.Xing L.Shu Y.c.ma K.Liu Institute of Metal Research Chinese Academy of SciencesShenyang 110016China MIIT Key Laboratory of Advanced Metallic and Intermetallic materials Technology Engineering Research Center of Materials Behavior and DesignMinistry of EducationNanjing University of Science and TechnologyNanjing 210094China

The phase transformation behavior of an as-cast Ti-42Al-5 Mn(at.%)alloy after subsequent quenching from 1380℃to 1000℃was investigated based on the differential thermal analysis(DTA),electron probe micro analyzer-backscattered electrons(EPma-BSE),transmission electron microscope(TEM)and X-ray diffraction(XRD).The results show that,the solidification path can be summarized as follows:Liquid→Liquid+β→β→β→α→β+α+γ→βo+α2+γ→βo+γ+α2/γ→βo+γ+α2/γ+βo,sec,with the phase transformationα→βtemperature(Tβ)=1311℃,phase transformationγ→βtemperature of(Tγsolv)=1231℃,phase transformationα2→αorβo→βtemperature(Tα2→α/Tβo→β)=1168 c,eutectoid temperature(Teut)=1132℃and T(α2/γ→βo,sec)≈1120℃.In comparison with Ti-42 Al alloy,the Teut and Tγsolv are slightly increased while both the Tp is decreased obviously by 5%Mn *** quenched from the temperature of 1380-1260℃,the martensitic transformationβ→α'could occur to form the needlelike martensite structure inβ*** kind of martensitic structure is much obvious with the increase of temperature from 1260℃to 1380℃.When the temperature is below Tγsolv(1231℃),theγgrains would nucleate directly from theβ*** the temperature slightly lower than T(eut)(1132℃),the dottedβ(o,sec)phases could nucleate in the lamellar colonies besides theγlamellae precipitated withinα2 ***,at room-temperature(RT),the alloy exhibits(po+α2+γ)triple phase with microstructure ofβo+lamellae+γ,of which the lamellar structure consists ofα2,γandβo,sec *** phase transformation mechanisms in this alloy,involvingβ→α',β→γ,α2→α2/γandα2→βo,sec were discussed.

关键词： Titanium aluminides Quenching Phase transformation Microstructure βphase

Translating codex Guidelines Into Application

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Biomedical and Environmental Sciences 2001年第1期14卷 149-149页

作者： ma cONcEPcION c.Lizada BureauofAgricultureandFisheriesProductStandards

condex texts include commodity and general standards, as well as texts of an advisory nature. The General Principles for codex Alimentarius define the ways in which commodity or general standards are accepted: (a) full, (b) with specified deviations, or (c) with a declaration of free distribution. The degree of acceptance partly defines the manner in which these texts are translated into application.

关键词： Developing countries Guideline Adherence Food Additives Food contamination Food Industry Humans Public Policy World Health Organization