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DNA mismatch repair in trinucleotide repeat instability

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Science China(life Sciences) 2017年第10期60卷 1087-1092页

作者： Jinzhen guo Luping Chen guo-min li Department of Radiation Oncology University of Texas Southwestern Medical Center Department of Biochemistry and Molecular Medicine Norris Comprehensive Cancer Center University of Southern California Keck School of Medicine

Trinucleotide repeat expansions cause over 30 severe neuromuscular and neurodegenerative disorders, including Huntington's disease, myotonic dystrophy type 1, and fragile X syndrome. Although previous studies have substantially advanced the understanding of the disease biology, many key features remain unknown. DNA mismatch repair(MMR) plays a critical role in genome maintenance by removing DNA mismatches generated during DNA replication. However, MMR components,particularly mismatch recognition protein MutSβ and its interacting factors MutLα and MutLγ, have been implicated in trinucleotide repeat instability. In this review, we will discuss the roles of these key MMR proteins in promoting trinucleotide repeat instability.

关键词： DNA mismatch repair trinucleotide repeat instability neurodegenerative diseases MutSβ

Activity Model and Its Application in Quarternary System CaO-FeO-SiO_2-WO_3

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Journal of Iron and Steel Research International 2010年第1期17卷 12-17页

作者： guo Pei-min li Zheng-bang ZHAO Pei State Key Laboratory for Advanced Iron and Steel Processes and Materials Central Iron andSteel Research Institute Beijing 100081 China

The activity model of CaO-FeO-SiO2-WO3 quarternary system is built according to the coexistence theory of slag structure and the reduction thermodynamics of scheelite is discussed by using this model. The activities of SiO2 and WO3 decrease, while the activity of CaO increases with increasing the basicity of slag. Among SiC, carbon and silicon reactants, the reducing capability of SiC is the strongest, while that of carbon is the poorest at high temperature （about 1 873 K）. Increasing the content of silicon or carbon is beneficial for increasing the yield of tungsten. Oxidizability of slag has a significant effect on the yield of tungsten. Controlling basicity and oxidizability of slag can decrease the oxidation loss of tungsten.

关键词： activity model scheelite thermodynamics direct reduction

Synthesis and Properties of Novel Polyimide Fibers Containing Phosphorus Groups in the Side Chain (DATPPO)

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Chinese Journal of Polymer Science 2017年第3期35卷 372-385页

作者： Yong Zhao guo-min li Fang-fang liu Xue-min Dai 董志鑫邱雪鹏 Polymer Composites Engineering Laboratory Changchun Institute of Applied Chemistry Chinese Academy of Sciences Changchun 130022 China University of Chinese Academy of Sciences Beijing 100049 China

A series of polyamic acid copolymers(co-PAAs) containing phosphorous groups in the side chains were synthesized from [2,5-bis(4-aminophenoxy) phenyl] diphenylphosphine oxide(DATPPO) and 4,4′-oxydianiline(ODA) with 3,3′,4,4′-biphenyltetracarboxylic dianhydride(s-BPDA) through the polycondensation in N,N′-dimethyacetamide(DMAc). The co-PAA solutions were spun into fibers by a dry-jet wet spinning process followed by thermal imidization to obtain co-polyimide(co-PI) fibers. FTIR spectra and elemental analysis confirmed the chemical structure of PI fibers. SEM results indicated that the resulting PI fibers had a smooth and dense surface, a uniform and circle-shape diameter. The thermogravimetric measurements showed that with the increase of DATPPO content, the resulting PI fibers possessed high decomposition temperature and residual char yield, indicating that the PI fibers had good thermal stability. The corresponding limiting oxygen index(LOI) values from the experiment results showed that the co-PI fibers possessed good flame-retardant property. Furthermore, the mechanical properties of the co-PI fibers were investigated systematically. When the DATPPO content increased, the tensile strength and initial modulus of the co-PI fibers decreased. However, the mechanical properties were improved by increasing the draw ratio of the fibers. When the draw ratio was up to 2.5, the tensile strength and initial modulus of the co-PI fibers reached up to 0.64 and 10.02 GPa, respectively. The WAXD results showed that the order degree of amorphous matter increased with increased stretching. In addition, the SAXS results displayed that valuably drawing the fibers could eliminate the voids inside and lead to better mechanical property. WAXD revealed that the orientation of the amorphous polymer influenced the mechanical properties of the fibers.

关键词： [2,5-Bis(4-aminophenoxy) phenyl] diphenylphosphine oxide Dry-jet wet spinning process Phosphorous Polyimide fibers

AO-resistant Properties of Polyimide Fibers Containing Phosphorous Groups in Main Chains

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Chinese Journal of Polymer Science 2016年第12期34卷 1469-1478页

作者： Yong Zhao guo-min li Xue-min Dai Fang-fang liu 董志鑫邱雪鹏 Polymer Composites Engineering Laboratory Changchun Institute of Applied ChemistryChinese Academy of SciencesChangchun 130022China University of Chinese Academy of Sciences Beijing 100049China

A series of polyimide fibers containing phosphorus element derived from （3-aminophenyl） methyl phosphine oxide （DAMPO） diamine was exposed to an artificial atomic oxygen environment which simulated the space environment in low earth orbit （LEO）. The mass loss, surface morphology, chemical composition, and mechanical properties of the fibers before and after atomic oxygen （AO） exposure were compared in detail with a blank sample. Results showed that the phosphor-containing fibers demonstrated lower mass change and less tensile strength reduction. SEM results showed that the fibers with phosphorous element had relatively dense surface after AO exposure. Meanwhile, XPS results indicated that a passivated phosphate layer, which could protect the following under-layer from attacking by AO, was formed on the surface of the fibers. These results indicated that the incorporation of diamine （DAMPO） into the main chains could protect the fibers for avoiding further erosion from AO exposure. Hence, the phosphor-containing PI fibers exhibits potential application in space fields.

关键词： Atomic oxygen Phosphorous Polyimide Fibers LEO environment.

Direct electrodeposition of ionic liquid-based template-free Sn Co alloy nanowires as an anode for li-ion batteries

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International Journal of minerals,Metallurgy and Materials 2018年第9期25卷 1027-1034页

作者： Le-ping Wang Gang Chen Qi-xin Shen guo-min li Shi-you Guan Bing li School of Materials science and Engineering East China University of Science and Technology Institute for Sustainable Energy Shanghai University

Sn Co alloy nanowires were successfully electrodeposited from Sn Cl2-Co Cl2-1-ethyl-3-methylimidazolium chloride(EMIC) ionic liquid without a template. The nanowires were obtained from the molar ratio of 5:40:60 for Sn Cl2(25)Co Cl2(25)EMIC at-0.55 V and showed a minimum diameter of about 50 nm and lengths of over 20 μm. The as-fabricated SnCo nanowires were about 70 nm in diameter and featured a Sn/Co weight ratio of 3.85:1, when used as an anode for a li-ion battery, they presented respective specific capacities of 687 and 678 m Ah·g^(-1) after the first charge and discharge cycle and maintained capacities of about 654 m Ah·g^(-1) after 60 cycles and 539 m Ah·g^(-1) after 80 cycles at a current density of 300 m A·g^(-1). Both the nanowire structure and presence of elemental Co helped buffer large volume changes in the Sn anode during charging and discharging to a certain extent, thereby improving the cycling performance of the Sn anode.

关键词： SnCo alloy nanowires template electrodeposition ionic liquid

Synthesis and AO Resistant Properties of Novel Polyimide Fibers Containing Phenylphosphine Oxide Groups in Main Chain

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Chinese Journal of Polymer Science 2019年第1期37卷 59-67,1-3页

作者： Yong Zhao Hong Gao guo-min li Fang-Fang liu Xue-min Dai Zhi-Xin Dong Xue-Peng Qiu Polymer Composites Engineering Laboratory Changchun Institute of Applied Chemistry Chinese Academy of Sciences University of Chinese Academy of Sciences China Academy of Space Technology

A series of co-polyimide(PI)fibers containing phenylphosphine oxide(PPO)group were synthesized by incorporating the bis(4-aminophenoxy)phenyl phosphine oxide(DAPOPPO)monomer into the PI molecular chain followed by dry-jet wet *** effects of DAPOPPO molar content on the atomic oxygen(AO)resistance of the fibers were investigated *** the AO fluence increased from 0to 3.2×1020the mass loss of the fibers showed the dependence on DAPOPPO molar content in co-PI *** PI fiber containing 40%DAPOPPO showed lower mass loss compared to those containing 0%and 20%*** higher AO fluence,the higher DAPOPPO content gave rise to dense carpet-like surface of *** results indicated that the passivated phosphate layer was deposited on the fiber surface when exposed to AO,which effectively prevented fiber from AO *** the DAPOPPO content increasing from 0%to 40%,the retentions of tensile strength and initial modulus for the fibers exhibited obvious growth from 44%to 68%,and 59%to 70%,after AO exposure with the fluence of 3.2×1020The excellent AO resistance benefits the fibers for application in low Earth orbit as flexible construction components.

关键词： Polyimide fibers Bis(4-aminophenoxy)phenyl phosphine oxide(DAPOPPO) Dry-jet wet spinning AO resistance

Mechanical Properties of Polyimide/Multi-walled Carbon Nanotube Composite Fibers

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Chinese Journal of Polymer Science 2016年第11期34卷 1386-1395页

作者： Zhi-xin Dong Tao Feng Chao Zheng guo-min li Fang-fang liu 邱雪鹏 Polymer Composites Engineering Laboratory Changchun Institute of Applied ChemistryChinese Academy of SciencesChangchun 130022China Academy of Space Electronic Information Technology Xi'an 710100China

A series of polyimide（PI）/multi-walled carbon nanotube（MWCNT） composite fibers were prepared by copolymerizing a mixture of monomers and carboxylic-functionalized MWCNTs, followed by dry-jet wet spinning, thermal imidization, and hot-drawing process. The content of the carboxylic groups of MWCNTs significantly increased when treated with mixed acid, whereas their length decreased with treatment time. Both the carboxylic content and length of MWCNTs influenced the mechanical properties of the composite fibers. Fiber added with 0.1 wt% MWCNTs treated for 4 h exhibited the best mechanical properties, i.e., 1.4 GPa tensile strength and 14.30% elongation at break, which were 51% and 32% higher than those of pure PI fibers, respectively. These results indicated that a suitable MWCNT content strengthened and toughened the resultant PI composite fibers, simultaneously. Moreover, raising draw ratio resulted in the increase of tensile strength and tensile modulus of the composite fibers.

关键词： walled nanotube tensile modulus resultant carboxylic length spinning elongation dispersed

RESEARCH OF MICRO ELECTRO DISCHARGE MACHINING EQUIPMENT AND PROCESS TECHNIQUES

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Chinese Journal of Mechanical Engineering 2002年第2期15卷 177-181页

作者： li Yong guo min li Fang Zhou Zhaoying Department of Precision Instruments and Mechanology, Tsinghua University, Beijing 100084, China Department of Precision Instruments and Mechanology Tsinghua University 北京 100084

Micro electro discharge machining (micro EDM) is a feasible way tomanufacture micro structures and has potential application in advanced industrial fields. For therealization of micro EDM, it is necessary to pay careful attention to its equipment design and thedevelopment of process techniques. The present status of research and development of micro EDMequipment and process techniques is overviewed. A micro electro discharge machine incorporated withan inchworm type of micro feed mechanism is introduced, and a micro electro discharge machine fordrilling micro holes suitable to industrial use is also introduced. Some of the machiningexperiments carried out on the micro EDM prototypes are shown and the feasibility of the micro EDMtechnology to practical use is discussed.

关键词： Micro electro discharge machining Inchworm mechanism Friction drivemechanism Micro electrode Micro hole Micro structure

Novel carbon nanohybrids as highly efficient magnetic resonance imaging contrast agents

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Nano Research 2015年第4期8卷 1259-1268页

作者： Rongli Cui Juan li Huan Huang mingyi Zhang Xihong guo Yanan Chang min li Jinquan Dong Baoyun Sun Gengmei Xing CAS Key Laboratory for Biomedical Effects of Nanomaterial & Nanosafety Institute of High Energy Physics Chinese Academy otScience (CAS) Beijing 700049 China

Novel carbon nanohybrids based on unmodified metallofullerenes have been successfully fabricated for use as a new magnetic resonance imaging （MRI） contrast agent. The nanohybrids showed higher R1 relaxivity and better brightening effect than Gd@C82（OH）x, in Tl-weighted MR images in vivo. This is a result of the proton relaxivity from the original gadofullerenes, which retained a perfect carbon cage structure and so might completely avoid the release of Gd^3＋ ions. A ＂secondary spin-electron transfer＂ relaxation mechanism was proposed to explain how the encaged Gd^3＋ ions of carbon nanohybrids interact with the surrounding water molecules. This approach opens new opportunities for developing highly efficient and low toxicity MRI contrast agents.

关键词： graphene oxide metallofullerene magnetic resonanceimaging (MRI) nanohybrids