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Reduced non-cpG methylation is a potential epigenetic target after spinal cord injury

Neural Regeneration Research 2023年第11期18卷 2489-2496页

作者： Zhourui Wu chen Li Ran Zhu Yiqiu cao Thomas C.Chen Liming cheng Key Laboratory of Spine and Spinal cord Injury Repair and Regeneration(Tongji University) Ministry of EducationShanghaiChina Division of Spine Department of OrthopedicsTongji HospitalTongji University School of MedicineShanghaiChina Institute of Spinal and Spinal cord Injury Tongji University School of MedicineShanghaiChina Department of Neurosurgery Keck School of MedicalUniversity of Southern CaliforniaLos AngelesCAUSA

DNA methylation is a critical epigenetic regulator in the occurrence and development of diseases and is closely related to various functional responses in relation to spinal cord injury.To investigate the role of DNA methylation in spinal cord injury,we constructed a library with reduced-representation bisulfite sequencing data obtained at various time points(day 0-42)after spinal cord injury in mice.Global DNA methylation levels,specifically non-cpG(cHG and cHH)methylation levels,decreased modestly following spinal cord injury.Stages post-spinal cord injury were classified as early(day 0-3),intermediate(day7-14),and late(day 28-42)based on similarity and hie rarchical cluste ring of global DNA methylation patterns.The non-cpG methylation level,which included cHG and cHH methylation levels,was markedly reduced despite accounting for a minor proportion of total methylation abundance.At multiple genomic sites,including the 5’untranslated regions,promoter,exon,intron,and 3’untranslated regions,the non-cpG methylation level was markedly decreased following spinal cord injury,whereas the cpG methylation level remained unchanged at these locations.Approximately one-half of the differentially methylated regions were located in intergenic areas;the other differentially methylated regions in both cpG and non-cpG regions were cluste red in intron regions,where the DNA methylation level was highest.The function of genes associated with differentially methylated regions in promoter regions was also investigated.From Gene Ontology analysis results,DNA methylation was implicated in a number of essential functional responses to spinal cord injury,including neuronal synaptic connection creation and axon regeneration.Notably,neither cpG methylation nor non-cpG methylation was implicated in the functional response of glial or inflammatory cells.In summary,our work elucidated the dynamic pattern of DNA methylation in the spinal co rd following injury and identified reduced noncpG methylation as an epigenetic target after spinal cor

关键词： cpG methylation cytosine fraction differentially methylated regions DNA methylation DNA methyltransferases dynamic signatures Gene Ontology non-cpG methylation single-cell RNA-Seq spinal cord injury

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A new localization theory of adaptive machining of near-net-shape blades

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chinese Journal of Aeronautics 2021年第6期34卷 18-32页

作者： Neng WAN Xiaogang SHEN Zhiyong cHANG Zezhong C.Chen Department of Mechanical Engineering Northwestern Polytechnical UniversityXi'an 710072China Department of Mechanical Industrial and Aerospace EngineeringConcordia UniversityMontrealQuebec H3G IMSCanada

In the fabrication of aero-engine blades,a great deal is gained when massive material removal is avoided at the end of the process,and as little as possible material is left on the blade billet.Due to the uncertainty of pre-process,the billet shapes are inconsistent.Sometimes,the near-net-shape billet doesn’t cover the blade design surface to be cut.Therefore,blade localization is necessary for these billets before the machining.In conventional localization methods,the design surface’s location focused on guaranteeing enough material to be cut.However,because the to-becut surface is in near-net and free-form shape,it is difficult to find a valid localized surface model to generate the tool path.Different from the localized surface is taken as rigid in previous investigation,it is allowed to deviate from the design surface no more than the tolerance band.In term of this principle,the tolerance band is utilized to promote localization ability.A series of optimization models with different priorities is established to avoid the abandonment expensive blade billet.Finally,with the experiments performed on the near-net-shape blades,the blade localization theory and the promotion of localization ability are verified.

关键词： Blade localization curvature constraint Machining surface Near-net-shape blade Tolerance constraint

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An automated approach to calculating the maximum diameters of multiple cutters and their paths for sectional milling of centrifugal impellers on a 4_(1/2)-axis cNc machine

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chinese Journal of Aeronautics 2019年第4期32卷 1030-1039页

作者： Baohai WU Zezhong C.Chen Ming LUO Dinghua ZHANG Feiyan HAN School of Mechanical Engineering Northwestern Polytechnical University Department of Mechanical Industrial and Aerospace EngineeringConcordia University college of Mechanical Engineering Xi'an University of Science and Technology

Power generators and chemical engineering compressors include heavy and large centrifugal impellers. To produce these impellers in high-speed machining, a 4?-axis milling machine(or a 4-axis machine plus an indexing table) is often used in the industry, which is more rigid than a5-axis milling machine. Since impeller blades are designed with complex B-spline surfaces and impeller channels spaces vary significantly, it is more efficient to use multiple cutters as large as possible to cut a channel in sections and a blade surface in patches, instead of only using a small cutter to machine a whole blade and a channel. Unfortunately, no approach has been established to automatically calculate the largest diameters of cutters and their paths, which include the indexing table angles. To address this problem, an automated and optimization approach is proposed. Based on the structure of a 4?-axis machine, a geometric model for a cutter gouging/interfering the impeller is formulated, and an optimization model of the cutter diameter in terms of the indexing table angle is established at a cutter contact(cc) point on a blade surface. Then, the diameters of the tools,their orientations, and the indexing table angles are optimized, and each tool's paths are generated for machining its corresponding impeller section. As a test, an impeller is efficiently machined with these tools section by section; thus, this approach is valid. It can be directly used in the industry to improve efficiency of machining centrifugal impellers.

关键词： Automated path generation 4_(1/2)-Axis cNc machining centrifugal impeller machining cutter diameter optimization Sectional machining

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为什么要发展教育研究型卫生系统?

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中国循证医学杂志 2013年第5期13卷 520-521页

作者： Lincoln C.Chen 蒋茜(译) 美国中华医学基金会主席不详

2012年11月，美国中华医学基金会（china Medical Board，cMB）联合复旦大学在上海共同主办了以加强中国教育研究型卫生系统（academichealthsystem，AHS）为主题的第四届西湖论坛。近200位学术界与政界领导出席了本届论坛，在其所提供... 详细信息

2012年11月，美国中华医学基金会（china Medical Board，cMB）联合复旦大学在上海共同主办了以加强中国教育研究型卫生系统（academichealthsystem，AHS）为主题的第四届西湖论坛。近200位学术界与政界领导出席了本届论坛，在其所提供的平台上，推出了强化和协调中国教育系统与卫生系统的概念基础和运作规则。

关键词：教育研究型卫生系统(AHS)

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Uni-axial and multi-axial Electromechanical couple behavior of PZT53

Uni-axial and multi-axial Electromechanical Couple behavior ...

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2012年海峡两岸破坏科学/材料试验学术会议

作者： Q.Wan C.Chen Y.P.Shen Institute of Structural Mechanics China Academy of Engineering Physics Key Laboratory School of Astronautics and AeronauticsXi'an Jiaotong University

The uni-axial and multi-axial electric-mechanical behavior are measured in the investigation.The results under two uni-axial loading mode show that when the loading parallel to the polarization and electric field,the compression has obvious effect on the remanent polarization, coercive field and strain magnitude,however when the loading perpendicular to the polarization and electric field,the loading has little effect on the remanent polarization,coercive field,the tension has obvious effected the strain magnitude.The multi-axial constitutive behavior of poled and unpoled PZT5 is measured under different proportional tension-torsion loading and compression-torsion loading until destroy.Deformation is measured using strain gauges.These results are used to map out "Switching" and "destroy" surfaces.The two surfaces are found to be a function of the polarization.Switching surface is similar to Drucker-Prager yield surface.Destroy behavior corresponds to maximal principal normal stress rule.For poled PZT53,the effect of bias electric field on its multiaxial behavior has also been exploited.The results indicated that the "Switching" surface disappear with the increased bias electric.The ultimate goal is to develop an experimentally validated micromechanics based phenomenological constitutive model for ferroelectric materials.

关键词： Uni-axial Multi-axial Electromechanical couple constitutive Switching Surface Destroy Surface

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A sinusoidal method for time-resolved quantification of dynamic brain extracellular space and diffusion tortuosity

A sinusoidal method for time-resolved quantification of dyna...

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中国神经科学学会第四次会员代表大会暨第八届全国学术会议

作者： Kevin C.Chen Multidisciplinary Research center Shantou University

A sinusoidal iontophoresis method was proposed to determine the dynamic modulations of two important parameters for characterizing extracellular diffusion,the brain extracellular volume and diffusion tortuosity,during shortlived pathological events.This method improved the commonly used step-release protocol in better characterization of the time-resolved diffusion tortuosity by measuring the phase lags and sinusoidal amplitudes of the sampled tetramethyl ammonium(TMA) concentration waveform.To validate the sinusoidal method,we tested whether the dynamic diffusion properties in the brain extracellular space can be extracted reliably from the TMA sinusoidal waveform through computersimulated experiments.The TMA mass balance equation was first modified to accommodate temporal changes of the brain extracellular space,followed by solving the mass balance equation numerically to model the in vitro and in vivo experimental situations incorporating a sinusoidal TMA point source.Simulations showed that the sinusoidal method can accurately capture the dynamic behaviors of the simulated brain extracellular volume and tortuosity both in vitro and in vivo,as long as no abrupt changes of the two parameters were encountered.The sinusoidal method also proved to be more accurate in inferring the relative extracellular volume changes man the traditional method of monitoring the TMA background concentration in vitro,which produced significant TMA undershoot artifacts following pathological events.

关键词： Extracellular Space Diffusion Ion-Selective Microelectrode Spreading Depression

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chemogenetic stimulation of nigrostriatal and mesolimbic projections affects sleep-wake behavior in rat

Chemogenetic stimulation of nigrostriatal and mesolimbic pro...

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中国神经科学学会第十二届全国学术会议

作者： Mei-Hong Qiu Michael C.Chen Jun Lu Department of Neurobiology School of Basic Medical Science Fudan University Department of Neurology Beth Israel Deaconess Medical Center and Harvard Medical School Department of Pharmacology School of Basic Medical Science Fudan University

Dopamine plays a complex role in sleep-wake systems. The exact effect of dopamine on these behaviors may depend on the downstream target of dopamine pathways. Using selective chemogenetic stimulation in rats, we dissected midbrain dopaminergic nigrostriatal and mesolimbic pathways and their effects on sleep. chemogenetic stimulation of nigrostriatal pathways increased sleep and cortical EEG delta power, while chemogenetic stimulation of mesolimbic pathways decreased sleep and cortical EEG power. These results indicate that midbrain dopamine（DA） in the basal ganglia has distinct roles in sleep-wake regulation.

关键词： dopamine sleep-wake mesolimbic pathway nigrostriatal pathway chemogenetic

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controlled buckling of thin film on elastomeric substrate in large deformation

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Theoretical & Applied Mechanics Letters 2011年第2期1卷 8-11页

作者： C.Chen W.Tao Z.J.Liu Y.W.Zhang J.Song Department of Mechanical and Aerospace Engineering University of MiamiCoral GablesFL 33146 Institute of Applied Mechanics Zhejiang UniversityHangzhou 310027China Institute of High Performance computing 1 Fusionopolic Way#16-16 Connexis138632Singapore

Electronic systems with large stretchability have many applications.A precisely controlled buckling strategy to increase the stretchability has been demonstrated by combining lithographically patterned surface bonding chemistry and a buckling process.The buckled geometry was assumed to have a sinusoidal form,which may result in errors to determine the strains in the film.A theoretical model is presented in this letter to study the mechanics of this type of thin film/substrate system by discarding the assumption of sinusoidal buckling geometry.It is shown that the previous model overestimates the deflection and curvature in the thin film.The results from the model agree well with finite element simulations and therefore provide design guidelines in many applications ranging from stretchable electronics to micro/nano scale surface patterning and precision metrology.

关键词： thin film buckling large deformation

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The Ductile to Brittle Transition Behavior of the Modified 9cr-1Mo Steel and Its Laser Welds

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材料导报 2004年第8期18卷 121-123页

作者： H.c.Wu R.K.Shiue C.Chen DepartmentofMaterialsScienceandEngineering TaiwanUniversityTaipei106ChinaTaiwan DepartmentofMaterialsScienceandEngineering DongHwaUniversityHualien974ChinaTaiwan

The ductile to brittle transition temperature (DBTT) of the modified 9cr-1Mo steel and its laser welds was studied. The increase in grain size of the weld structure ascended the DBTT of the steel significantly. The transformation of retained austenite at martensite interlath boundaries into untempered and/or twinned martensite could also contribute to increased DBTTs of the steel and its welds tempered at 540℃.

关键词： 9cr-1Mo钢激光焊接 DBTT 冲击韧性

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Nanoscale strain engineering of graphene and graphene-based devices

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Acta Mechanica Sinica 2016年第3期32卷 497-509页

作者： N.-c.Yeh c.-c.Hsu M.L.Teague J.-Q.Wang D.A.Boyd c.-C.Chen Department of Physics Institute for Quantum Information and Matter and Kavli Nanoscience InstituteCalifornia Institute of Technology Department of Physics Fudan University Department of Physics California Institute of Technology

Structural distortions in nano-materials can induce dramatic changes in their electronic properties. This situation is well manifested in graphene, a two-dimensional honeycomb structure of carbon atoms with only one atomic layer thickness. In particular, strained graphene can result in both charging effects and pseudo-magnetic fields, so that controlled strain on a perfect graphene lattice can be tailored to yield desirable electronic properties. Here, we describe the theoretical foundation for strain-engineering of the electronic properties of graphene, and then provide experimental evidence for strain-induced pseudo-magnetic fields and charging effects in monolayer graphene. We further demonstrate the feasibility of nano-scale strain engineering for graphene-based devices by means of theoretical simulations and nano-fabrication technology.

关键词： Graphene Strain-engineering Nanostructures Dirac fermions Pseudo-magnetic field Valleytronics

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