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Journal of Materials Science & Technology 2022年第22期117卷 8-22页

作者： Young-Kyun Kim kee-Ahn Lee Department of Materials Science and Engineering Inha UniversityIncheon 22212Republic of Korea Korea Institute of Materials Science(KIMS) Changwon 51508Republic of Korea

High-entropy alloys(HEAs)with interstitial atoms that are produced by additive manufacturing have gained intensive interest in the materials science community because of their suitability for constructing high-strength net-shape ***,a strategy to additionally enhance the strength of selective laser melted carbon-containing HEAs was *** as-built carbon-containing HEAs(C_(x)(Cr_(20)Mn_(20)Fe_(20)Co_(20)Ni_(20))_(100-x)(x=0.5 at.%,1.0 at.%,and 1.5 at.%))contain supersaturated carbon,and the extent of supersaturation increases as the carbon content *** subjected to aging treatment at 650°C for 1 h,the microstructure of the three alloys did not change at the grain ***,the microstructure at the sub-grain scale changed markedly,and these changes influenced the tensile properties and deformation *** particular,the tensile strength of aged 1.5C-HEA at 650°C was∼1.2 GPa at room temperature,which is higher than those reported for CrMnFeCoNi ***,the main deformation mechanism changed from deformation twinning to dislocation-mediated slip,resulting in much higher strain hardening capacity after the aging *** work led to the development of an alternative promising method that involves tailoring the microstructure,to enhance the mechanical properties of additively manufactured metallic materials that contain interstitial atoms.

关键词： Selective laser melting High-entropy alloy Carbon contents Aging Microstructure evolution Tensile property Deformation mechanism

Insights into female germ cell biology： from in vivo development to in vitro derivations

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Asian Journal of Andrology 2015年第3期17卷 415-420页

作者： Dajung Jung Kehkooi kee Department of Basic Medical Sciences Center for Stem Cell Biology and Regenerative Medicine School of Medicine Tsinghua University Beijing 100084 China

Understanding the mechanisms of human germ cell biology is important for developing infertility treatments. However, little is known about the mechanisms that regulate human gametogenesis due to the difficulties in collecting samples, especially germ cells during fetal development. In contrast to the mitotic arrest of spermatogonia stem cells in the fetal testis, female germ cells proceed into meiosis and began folliculogenesis in fetal ovaries. Regulations of these developmental events, including the initiation of meiosis and the endowment of primordial follicles, remain an enigma. Studying the molecular mechanisms of female germ cell biology in the human ovary has been mostly limited to spatiotemporal characterizations of genes or proteins. Recent efforts in utilizing in vitro differentiation system of stem cells to derive germ cells have allowed researchers to begin studying molecular mechanisms during human germ cell development. Meanwhile, the possibility of isolating female germline stem cells in adult ovaries also excites researchers and generates many debates. This review will mainly focus on presenting and discussing recent in vivo and in vitro studies on female germ cell biology in human. The topics will highlight the progress made in understanding the three main stages of germ cell developments： namely, primordial germ cell formation, meiotic initiation, and folliculogenesis.

关键词： embryonic stem cell female germline stem cell folliculogenesis in vitro derivations meiotic initiation primordial germ cell

Effect of asymmetrical channel chirping on field intensity patterns of supermodes and modal discrimination in index guided laser arrays

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Journal of Central South University 2014年第9期21卷 3513-3517页

作者： kee-Young Kwon College of Engineering Kongju National University

The effect of channel-width chirping on near- and far-field intensity patterns of the six supermodes was investigated. The supermode discrimination was evaluated in various channel-chirped index guided laser arrays. The results show that the linearly channel-chirped laser array has very good supermode discrimination which is better than that of a uniform laser array, the V channel-chirped laser array has the smallest radiation angle of the fundamental supermode among the calculated arrays, and the asymmetrically V channel-chirped array has a very small radiation angle of the fundamental supermode, which is smaller than that of the uniform array and also allows for very good fundamental supermode discrimination against the higher-order supermodes, which is better than that of the V channel-chirped laser array.

关键词： laser array channel-width chirping field pattern modal gain

Exotic structures arising from fake projective planes

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Science China Mathematics 2013年第1期56卷 43-54页

作者： YEUNG Sai-kee Department of Mathematics Purdue University

We present examples of exotic structures on pPC2#qPC2 for some small p and q obtained naturally from quotients of fake projective planes in complex geometry,which are classified by the work of Prasad-Yeung and Cartwri... 详细信息

关键词： exotic four-folds fake projective planes

Extensions of 2-Homogeneous Polynomials on c_0

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Acta Mathematica Sinica,English Series 2008年第5期24卷 877-880页

作者： Pi-kee LIN Department of Mathematics University of MemphisMemphis TNUSA 38152

We prove that every 2-homogeneous polynomial on the complex co has a unique normpreserving extension to its bidual l∞.

关键词： Hahn-Banach extension homogeneous polynomial

Comparative Optical Separation of Racemic Ibuprofen by Using Chiral Stationary Phase

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Chinese Journal of Chemical Engineering 2002年第6期10卷 681-685页

作者： Dalkeun PARK Joong kee LEE 等 Nano-EcoResearchCenter KISTSeoul136-791Korea ChemicalEngineeringDepartment HongikUniversitySeoul121-791Korea

Ibuprofen is widely used as a non-steroidal anti-inflammatory drug and produced as racemic mixture. Its pharmacological activity resides only in S-(+)-enantiomer, and R-()-enantiomer is not only inactive but also has many side effects. Thus it is necessary to separate R-enantiomer from racemic ibuprofen. We studied optical separation of racemic Ibuprofen with chiral high performance liquid chromatography (HPLC). Out of three different chiral stationary phases, which were selected on the basis of structure and availability, two were found to be ef-fective. There was optimum eluent composition for each stationary phase for good resolution in optical separation. Resolution decreased with increase of eluent flow rate, but effect of injection volume on resolution was insignificant at high eluent flow rate.

关键词： ibuprofen enantiomer separation high performance liquid chromatography chiral stationary phase

Numerical Analysis of Secondary Cooling in Continuous Slab Casting

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Journal of Materials Science & Technology 2008年第3期24卷 389-390页

作者： kee-Hyeon Cho Byung-Moon Kim Research Institute of Industrial Science & Technology GyeongBuk Regional Stragetic Agency for Innovation

In the present study, a numerical optimization program has been developed for predicting the optimal secondary cooling patterns in a continuous slab caster. Optimization strategy using Broydon-Fletcher-Goldfarb-Shanno （13FGS） method is carried out by determining the constant heat transfer coefficients in each spray zone, which could satisfy the casting conditions and metallurgical criteria specified by the engineer. From the present results, it is found that even a slight variation in the pouring temperature, allowable surface temperature, and casting speed could give rise to the changes in the cooling pattern throughout the spray zones.

关键词： Continuous casting Secondary cooling Optimization

Addendum to:Exotic structures arising from fake projective planes(Sci China Math,2013,56:43-54)

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Science China Mathematics 2015年第11期58卷 2473-2476页

作者： YEUNG Sai-kee Department of Mathematics Purdue University

The goal of this addendum is to generalize the argument of the original article [5] to handle the case of Cartwright-Steger surface, and to correct misprints in the tables in [5].

关键词：射影平面数学科学中国结构表面

Optical Code Generating Device Using 1×N Asymmetric Hollow Waveguide Couplers

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光子学报 2008年第5期37卷 849-854页

作者： Abang Annuar EHSAN Sahbudin SHAARI Mohd Kamil ABD. RAHMAN kee Mohd Rafique kee ZAINAL ABIDIN Institute of Microengineering and Nanoelectronics Universiti Kebangsaan Malaysia 43600 UKM Bangi Selangor Malaysia Faculty of Applied Science Universiti Teknologi MARA 40450 Shah Alam Selangor Malaysia Kulliyyah of Science International Islamic University Malaysia P. 0 t3oJ＂ 141 25710 Kuantan Pahang Darul Makmur Malaysia)

An optical code generating device for security access system application is presented. The code generating device constructed using asymmetric hollow optical waveguide coupler design provides a unique series of output light intensities which are successively used as an optical code. The design of the waveguide is made using two major components which are asymmetric Y-junction splitter and a linear taper. Waveguiding is done using a hollow waveguide structure. Construction of higher level 1×N hollow waveguide coupler is done utilizing a basic 1×2 asymmetric waveguide coupler design together with a cascaded design scheme. Non-sequential ray tracing of the asymmetric hollow optical waveguide couplers is performed to predict the optical transmission properties of the waveguide. A representation of the code combination that can be generated from the device is obtained using combinatory number theory.

关键词：光代码光子波导耦合器安全接入系统

Novel manganese(Ⅱ)-based deep eutectic solvents: Synthesis and physical properties analysis

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Chinese Chemical Letters 2015年第10期26卷 1311-1314页

作者： Koon-kee Kow Kamaliah Sirat Department of Chemistry Faculty of Science Universiti Putra Malaysia

Type IV deep eutectic solvent（DES） involves the formation of metal-based eutectics from metal salts or metal salt hydrate in combination with various hydrogen-bond donors（HBDs） such as urea, ethylene glycol or acetamide. In current study, two distinguished approaches were used to synthesize potential DESs, given as the direct heating and the evaporating methods. Successful synthesized DESs were subjected for physical properties characterization by Fourier Transform Infrared（FTIR） Spectroscopy, thermal stability, viscosity,and conductivity analyses. Five novel manganese（II）-based DESs were successfully synthesized as reported in this study. Data obtained indicated that the Mn Cl2á4H2Oáacetamide DES exhibits the lowest freezing point（27.5℃）, highest thermal stability（193℃ point of dehydration）, lowest viscosity（E = 112.8cP） and the highest conductivity（0.12723 mS/cm）. The findings obtained reveal the characteristics, nature or features of synthesized DESs as potential industrial solvents.

关键词： Ionic liquid Deep eutectic solvents Manganese Solvent synthesis Physical properties