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Synapsing with NG2 cells(polydendrocytes),unappreciated barrier to axon regeneration?

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Neural Regeneration Research 2015年第3期10卷 346-348页

作者： Young-Jin son Shriners Hospitals Pediatric Research Center and Department of Anatomy and Cell Biology Temple University School of Medicine

Have you heard of NG2 cells or NG2 glia or polydendro- cytes~. These are new names for the precursor cells that used to be referred to as oligodendrocyte precursor cells （OPCs）, which become the oligodendrocytes that myelinate central nervous system （CNS） axons. Evidence suggests, however, that they have other functions, besides differentiating into oligodendrocytes. Most notably, the OPCs/NG2 cells are uni- formly distributed in grey matter as well as in white matter, which matches poorly with the distribution of myelinating oligodendrocytes. Furthermore, not every NG2 cell is fated to become an oligodendrocyte. Hence the term OPC can be fairly applied only when discussing the role of these cells in the oligodendrocyte lineage.

关键词： NG cell Synapsing with NG2 cells polydendrocytes unappreciated barrier to axon regeneration

Determination of the solvation film thickness of dispersed particles with the method of Einstein viscosity equation

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Journal of University of Science and Technology Beijing 2005年第4期12卷 370-375页

作者： changsheng Peng Shaoxian son Shouci Lu College of Environmental Science and Engineering Ocean University of China Qingdao 266003 China Instituto de Metalurgia Universidad Autónoma de San Luis Potosí Av. Sierra Leona 550 San Luis Potosí C.P. 78210 Mexico Civil and Environmental Engineering School University of Science and Technology Beijing Beijing 100083 China

The dispersion of a solid particle in a liquid may lead to the formation of solvation film on the particle surface, which can strongly increase the repulsive force between particles and thus strongly affect the stability of dispersions. The solvation film thickness, which varies with the variation of the property of suspension particles and solutions, is one of the most important parameters of the solvation film, and is also one of the most difficult parameters that can be measured accurately. In this paper, a method, based on the Einstein viscosity equation of dispersions, for determining the solvation film thickness of particles is developed. This method was tested on two kinds of silica spherical powders （namely M1 and M2） dispersed in ethyl alcohol, in water, and in a water-ethyl alcohol mixture （1：1 by volume） through measuring the relative viscosity of dispersions of the particles as a function of the volume fraction of the dry particles in the dispersion, and of the specific surface area and the density of the particles. The calculated solvation film thicknesses on M1 are 7.48, 18.65 and 23.74 nm in alcohol, water and the water-ethyl alcohol mixture, 12.41, 12.71 and 13.13 nm on M2 in alcohol, water and the water-ethyl alcohol mixture, respectively.

关键词： solvation film viscosity film thickness Einstein viscosity equation

Dislocation characteristics and dynamic recrystallization in hot deformed AM30 and AZ31 alloys

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Journal of Magnesium and Alloys 2022年第12期10卷 3495-3505页

作者： Hyeon-Woo son Soong-Keun Hyun Metallic Materials Division Korea Institute of Materials ScienceChangwon 51508Republic of Korea Department of Materials Science and Engineering Inha UniversityIncheon 22212Republic of Korea

Zn addition to Mg alloys activates non-basal slip or twinning with solute softening *** the other hand,the effects of the Zn solute on the macroscopic dislocation behavior and dynamic recrystallization are not completely ***,it is unclear ifslip can be affected by changes in the c/a ratio of solute *** study was conducted to understand the solute strengthening of Zn addition and its effects on the dislocation characteristics and dynamic recrystallization.A hot torsion test was performed on both AM30 and AZ31 alloys up to a high strain to investigate the Zn solute effect on the dislocation characteristics and dynamic *** dislocation components of the hot torsioned alloys were evaluated by X-ray line profile analysis and electron backscatter *** results showed that the Zn solutes slightly accelerate strain accumulation at the initial stages of hot deformation,which accelerated recrystallization at high *** dislocation characteristics were changed dynamically by Zn addition:fortified-type slip,dislocation arrangement and strain anisotropy *** most important point was that the dislocation characteristics were changed dramatically at the critical strain for recrystallization and high strain *** addition of Zn also acted greatly in these strain *** indicates that the rapid formation of-type slip at the serrated grain boundaries occurs at the initiation of dynamic recrystallization and the increase in the grain triple junction because grain refinement has a great influence on the dislocation characteristics at high strain.

关键词： Magnesium alloy X-ray line profile Solid solution Dislocation density Dynamic recrystallization

Genetic Algorithm to Optimize the Design of Main Combustor and Gas Generator in Liquid Rocket Engines

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Journal of Thermal Science 2014年第3期23卷 259-268页

作者： Min son Sangho Ko Jaye Koo Graduate Student Korea Aerospace University School of Aerospace and Mechanical Engineering Korea Aerospace University

A genetic algorithm was used to develop optimal design methods for the regenerative cooled combustor and fuel-rich gas generator of a liquid rocket engine. For the combustor design, a chemical equilibrium analysis was applied, and the profile was calculated using Rao's method. One-dimensional heat transfer was assumed along the profile, and cooling channels were designed. For the gas-generator design, non-equilibrium properties were derived from a counterflow analysis, and a vaporization model for the fuel droplet was adopted to calculate residence time. Finally, a genetic algorithm was adopted to optimize the designs. The combustor and gas generator were optimally designed for 30-tonf, 75-tonf, and 150-tonf engines. The optimized combustors demonstrated superior design characteristics when compared with previous non-optimized results. Wall temperatures at the nozzle throat were optimized to satisfy the requirement of 800 K, and specific impulses were maximized. In addition, the target turbine power and a burned-gas temperature of 1000 K were obtained from the optimized gas-generator design.

关键词： Liquid Rocket Engine Main Combustor Gas Generator Optimization Genetic Algorithm

Kinematic Analysis of the Neck and Upper Extremities During Walking in Healthy Young Adults

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Journal of Bionic Engineering 2011年第3期8卷 305-312页

作者： Kwon son Junghong Park Seonghun Park School of Mechanical Engineering Pusan National University Busan 609-735 Republic of Korea

The objective of this paper is to quantify the local stabilities of the neck and upper extremities （right/left shoulders and right/left elbows）, and investigate differences between linear and nonlinear measurements of the associated joint motions and differences in the local stability between the upper and lower extremities. This attempt involves the calculation of a nonlinear parameter, Lyapunov Exponent （LE）, and a linear parameter, Range of Motion （ROM）, during treadmill walking in conj unction with a large population of healthy subjects. Joint motions of subjects were captured using a three-dimensional motion-capture system. Then mathematical chaos theory and the Rosenstein algorithm were employed to calculate LE of joints as the extent of logarithmic divergence between the neighboring state-space trajectories of flexion-extension angles. LEs computed over twenty males and twenty females were 0.037~0.023 for the neck, 0.043＋0.021 for the right shoulder, 0.045i0.030 for the left shoulder, 0.032i0.021 for the right elbow, and 0.034~0.026 for the left elbow. Although statistically significant difference in the ROM was observed between all pairs of the neck and upper extremity joints, differences in the LE between all pairs of the joints as well as between males and females were not statistically significant. Between the upper and lower extremities, LEs of the neck, shoulder, and elbow were significantly smaller than those of the hip （-0.064） and the knee （-0,062）. These results indicate that a statistical difference in the local stability between the upper extremity joints is not significant. However, the different result between the ROM and LE gives a strong rationale for applying both linear and nonlinear tools together to the evaluation of joint movement. The LEs of the joints calculated from a large population of healthy subjects could provide normative values for the associated joints and can be used to evaluate the recovery progress of patients with joint rel

关键词： kinematic analysis Lyapunov exponent range of motion chaos theory upper extremities

The Immersed Interface Hybridized Difference Method for Parabolic Interface Problems

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Numerical Mathematics(Theory,Methods and Applications) 2022年第2期15卷 336-359页

作者： Youngmok Jeon son-Young Yi Department of Mathematics Ajou UniversitySuwon 16499Republic of Korea Department of Mathematical Sciences The University of Texas at El PasoEl PasoTX 79968USA

We propose several immersed interface hybridized difference methods(IHDMs),combined with the Crank-Nicolson time-stepping scheme,for parabolic interface *** IHDM is the same as the hybrid difference method away from the interface cells,but the finite difference operators on the interface cells are modified tomaintain the same accuracy throughout the entire *** themodification process,we consider virtual extensions of two sub-solutions in the interface cells in such a way that they satisfy certain jump equations between *** propose several different sets of jump equations and their resulting discrete methods for one-and two-dimensional *** numerical results are presented to demonstrate the accuracy and robustness of the proposed methods.

关键词： Parabolic interface problem hybrid difference method immersed interface

Effects of land-use types and the exotic species,Hypochaeris radicata,on plant diversity in human-transformed landscapes of the biosphere reserve,Jeju Island,Korea

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Plant Diversity 2023年第6期45卷 685-693页

作者： Deokjoo son Bruce Waldman Uhram song College of Education Department of Science Education Dankook UniversityGyeonggi-do16890Republic of Korea Department of Integrative Biology Oklahoma State UniversityStillwaterOK 74078USA Department of Biology Jeju National UniversityJeju 63243Republic of Korea

Land-use and plant invasion influence *** the effects of land-use types and invasive plants on the ecosystem is crucial for better management and the development of strategic plans for increasing biodiversity in Jeju Island,Korea,a designated Biosphere Reserve by the United Nations Education,Scientific,and Cultural *** effect of the most dominant invasive exotic species,Hypochaeris radicata,on the four land-use types of Jeju Island was *** composition,soil characteristics,and plant diversity among four land-use types(cropland,green space,neglected land,and residential)were *** the land-use types,croplands had the most diverse plant composition and the highest richness in exotic and native plant ***,such as tangerine orchards,which are widely distributed throughout Jeju Island,showed the highest plant diversity because of medium intensity disturbance caused by weed *** relative cover of *** did not differ between land-use ***,*** invasion was negatively related with plant species richness,making this invasive species a threat to the biodiversity of native herbs present in land-use *** adapts to areas with a broad range of soil properties and a variety of land-use ***,it is crucial to monitor land-use types and patterns of plant invasion to guide the implementation of consistent management and conservation strategies for maintaining ecosystem integrity of the transformed habitat in Jeju Island.

关键词： Biosphere reserve Cropland Invasive exotic plant Plant richness Intermediate disturbance hypothesis

Effects of Melandrium firmum methanolic extract on testosterone-induced benign prostatic hyperplasia in Wistar rats

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Asian Journal of Andrology 2012年第2期14卷 320-324页

作者： Mee-Young Lee In-Sik Shin chang-Seob Seo Nam-Hun Lee Hye-Kyung Ha Jong-Keun son Hyeun-Kyoo Shin Herbal Medicine EBM Research Center Korea institute of Oriental MedicineExporo 483Yusung-guDaejeon 305-811Koreaand Coilege of Pharmacy Yeungnam UniversityGyonsan 712-749Korea

Benign prostatic hyperplasia （BPH） is an age-related disease of unknown aetiology characterized by prostatic enlargement coincident with distinct alterations in tissue histomorphology. Instead of therapeutic agents that can cause severe side effects, plant extracts are frequently used to treat BPH. In this study, we investigated whether the Melandrium firmum methanolic extract （MFME） improves BPH, using the testosterone propionate （TP）-induced BPH rat model. Castration was performed via the scrotal route under sodium pentobarbital anaesthesia. BPH in castrated rats was generated via daily subcutaneous injections of TP （3 mg kg-1） dissolved in corn oil, for 4 weeks. MFME was administered daily by oral garage at a dose of 200 mg kg-1 for 4 weeks, along with the TP injections. The control group received injections of corn oil subcutaneously. At the scheduled termination of the experiment, all rats were killed and their prostates weighed; the relative prostate weight （prostate/body weight ratio） was calculated, and histomorphological changes in the prostate were examined. Additionally, we measured the levels of testosterone and dihydrotestosterone （DHT） in the serum and the prostate. Experimentally induced BPH led to marked decreases in the relative prostate weight and the DHT levels in the serum and the prostate. Histologically, BPH was evident in the ventral lobe of the prostate, and MFME treatment suppressed the severity of the lesions. These results indicate that MFME effectively inhibits the development of BPH induced by testosterone in a rat model. Further studies will be needed to identify the compound（s） responsibility for inducing the protective effect against BPH and determine its mechanism of action,

关键词： benign prostatic hyperplasia dihydrotestosterone Melandrium firmum (S. et Z.)RoHRB prostate testosterone

A survey of free space optical networks

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Digital Communications and Networks 2017年第2期3卷 67-77页

作者： In Keun son Shiwen Mao Department of Electrical and Computer Engineering Auburn University Auburn AL USA Defense Acquisition Program Administration (DAPA) Republie of Korea

Free Space Optical （FSO） networks, also known as optical wireless networks, have emerged as viable candidates for broadband wireless communications in the near future. The range of the potential application of FSO networks is extensive, from home to satellite. However, FSO networks have not been popularized because of insufficient availability and reliability. Researchers have focused on the problems in the physical layer in order to exploit the properties of wireless optical channels. However, recent technological developments with successful results make it practical to explore the advantages of the high bandwidth. Some researchers have begun to focus on the problems of network and upper layers in FSO networks. In this survey, we classify prospective global FSO networks into three subnetworks and give an account of them. We also present state-of- the-art research and discuss what kinds of challenges exist.

关键词： Wireless access networks Free space optical networks Free space optical communications Network architecture Optical wireless networks Satellite networks