Urchin-Like Ni Microspherical Structure with Enhanced Magnetic Loss for Thin Microwave Absorber at Gigahertz

Yuping Sun,Zhengwu Pan,Hongming Long,Siu Wing Or,S. L. Ho,Chao Feng,Xianguo Liu 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2017 NANO Vol.12 No.3

We describe in this report a wet chemical reduction synthetic strategy for synthesizing urchin-like Ni microspherical structures, in which the nanowires self-assembled by Ni nanoparticles with the size of 5–20 nm are assembled in a radial form from the center to the surface of the spherical oriented arrays. Urchin-like Ni microspherical structures exhibit the strong magnetic natural resonance peak at 7.0 GHz and superior magnetic loss at 2–18 GHz, originated from relatively high anisotropy energy of urchin-like shape. Electromagnetic absorption measurements show that the urchin-like Ni microspherical structures possess outstanding microwave absorption performance at 2–18 GHz. An optimal reflection loss of –21.98 dB can be observed at 17.4 GHz with a matching thickness of 1.4 mm and the effective absorption (below –10 dB, 90% absorption) bandwidth is 5 GHz (12–17 GHz) with a thickness of 1.7 mm. The excellent microwave absorption performance may be attributed to the good impedance, large attenuation constant and novel magnetic loss ability.

Effects of Task-Based Intercultural Instruction on EFL Students’ Intercultural Competence and Language Abilities

Yuping Sun,Na-Young Kim 한국영어교과교육학회 2021 영어교과교육 Vol.20 No.4

This study was designed to investigate the effects of Task-Based Intercultural Instruction (TBII) on Chinese EFL students’ intercultural competence and language abilities, focusing on reading and writing. A total of 102 freshmen at a university in China participated in this study. They were randomly divided into one experimental group (n = 50) and one control group (n = 52). During the 16-week experimental period, both groups received Task-Based Language Teaching (TBLT), though the experimental group was integrated with intercultural instruction while the control group did not receive intercultural instruction. Before and after the experimental period, there were pre- and post-surveys on intercultural competence and pre- and post-tests regarding language abilities. Paired sample t-tests between the pre- and post-surveys and pre- and post-tests were administered to determine the effects of TBII. Independent t-tests were also performed to compare the differences between the two groups regarding intercultural competence and reading and writing abilities. The findings revealed statistically significant mean score changes in the participants’ intercultural competence in the experimental group. Furthermore, both groups showed significant improvements regarding reading and writing abilities. Based on these findings, pedagogical suggestions are made for EFL learning.

Computational design towards energy efficient optimization in overconstrained robotic limbs

Gu Yuping,Wang Ziqian,Feng Shihao,Sun Haoran,Lu Haibo,Pan Jia,Wan Fang,Song Chaoyang 한국CDE학회 2023 Journal of computational design and engineering Vol.10 No.5

Legged robots are constantly evolving, and energy efficiency is a major driving factor in their design. However, combining mechanism efficiency and trajectory planning can be challenging. This work proposes a computational optimization framework for optimizing leg design during basic walking while maximizing energy efficiency. We generalize the robotic limb design as a four-bar linkage-based design pool and optimize the leg using an evolutionary algorithm. The leg configuration and design parameters are optimized based on user-defined objective functions. Our framework was validated by comparing it to measured data on our prototype quadruped robot for forward trotting. The Bennett robotic leg was advantageous for omni-directional locomotion with enhanced energy efficiency.

Notch ligand Jagged1 promotes mesenchymal stromal cell-based cartilage repair

Junkui Sun,Zhengliang Luo,Guangxi Wang,Yuping Wang,Yisheng Wang,Margaret Olmedo,Massimo Max Morandi,Shane Barton,Christopher G. Kevil,Bing Shu,Xifu Shang,Yufeng Dong 생화학분자생물학회 2018 Experimental and molecular medicine Vol.50 No.-

Placenta-derived mesenchymal stromal cells (PMSCs) provide a promising cell source for tissue regeneration. However, rapid induction of PMSC chondrogenic differentiation during therapeutic transplantation remains extremely challenging. Here we undertook a study to determine if Notch inhibition by soluble Jagged1 (JAG1) peptides could be utilized to accelerate PMSC-induced cartilage regeneration in a mouse post-traumatic osteoarthritis (PTOA) model. Our results showed that treatment of PMSCs with soluble JAG1 significantly enhanced chondrogenesis in culture as shown by increased alcian blue staining and decreased Notch target Hes1 expression when compared to those in lgG-treated control cells. Importantly, significantly enhanced cartilage formation and decreased joint inflammation were observed when JAG1-treated PMSCs were injected into mouse PTOA knee joints. Finally, in vivo cell tracing showed that more JAG1-treated PMSCs remained in knee joint tissues and that JAG1-treated PMSCs exhibited greater PMSC chondrogenic differentiation than lgG-treated control PMSCs at 4 weeks after injection. These data indicate that transient Notch inhibition by soluble JAG1 could be used to enhance PMSC survival and chondrogenic differentiation, thereby increasing the therapeutic potential of PMSCs for cartilage regeneration.

High catalytic performance of CuO nanocrystals with largest defects

Chunfang Zhang,Yuping Sun,Yunxiang Bai,Yanqi Yin,Jin Gu 한국화학공학회 2011 Korean Journal of Chemical Engineering Vol.28 No.2

To improve the calalytic performance of CuO, nanometer-sized CuO particles were prepared with ultrafiltration surface contact method (UMSCM). X-ray powder diffraction (XRD) and scanning electron microscopy (SEM)were used to characterize the crystal structure and morphology of the particles made with UMSCM, hydrothermal method,grounding method as well as a commercial one. SEM results illustrate that UMSCM prepared CuO particles mainly show the form of orthorhombic sliced crystals with the largest amounts of defects compared to CuO particles made by the other three methods. In the oxidation of cumene, CuO prepared with UMSCM also shows better catalytic performance than the other three particles, which can be ascribed to its smaller particle sizes and larger defects so as to accelerate the surface adsorption rate of O_2 molecules and the diffusion of ions and atoms, thus improving the catalytic activity.

Comparative Study on the Effects of D-Psicose and D-Fructose in the Maillard Reaction with β-Lactoglobulin

Yan Zeng,Huan Zhang,Yuping Guan,Lili Zhang,Yuanxia Sun 한국식품과학회 2013 Food Science and Biotechnology Vol.22 No.2

D-Psicose, recognized as a noncaloric sweetener,has shown a great potential in food industry. In the present study, D-psicose and D-fructose were used to modify bovine β-lactoglobulin (β-Lg) through Maillard reaction. The Maillard reaction process and the physicochemical and structural properties of the modified proteins were also investigated. The result showed that compared to Dfructose,D-psicose played a more effective role in the Maillard reaction, especially after the initial stage of the reaction. Moreover, the modified β-Lg with D-psicose had more polymeric compounds, higher antioxidant activity,but lower thermal stability than that with D-fructose. These findings, especially the structural changes of the modified proteins, supplied detail information on the Maillard reaction of D-psicose, and could provide some guidance to the practical applications of this rare sugar on food industry.

Study on the Solid Phase Extraction of Hg(II)-SBDTR Chelate with C18 Disks and Its Application to the Determination of Mercury in Tobacco and Tobacco Additive

Guangyu Yang*,Zhenyuang Xia,Yuping Wu,Handong Sun,Jiayuan Yin 대한화학회 2004 Bulletin of the Korean Chemical Society Vol.25 No.4

Experimental Investigation on Seismic Resistance of RC Shear Walls with CFRP Bars in Boundary Elements

Jun Zhao,Fuqiang Shen,Chenzhe Si,Yuping Sun,Lu Yin 한국콘크리트학회 2020 International Journal of Concrete Structures and M Vol.14 No.1

Experimental investigation on seismic performance of RC shear walls reinforced with CFRP bars in boundary elements to enhance the resilience was presented which is expected for stable resistance capacity and small residual deformation. Six RC shear walls reinforced with CFRP bars as longitudinal tensile materials in boundary elements were tested under reversed cyclic lateral loading while subjected to constant axial compression with different axial load ratios of 0.17, 0.26 and 0.33, respectively. Two forms of stirrups were used for each axial load ratio, which were rectangular and circular stirrups in boundary elements. A reference specimen, ordinary RC shear walls, was also introduced to certify the excellence of CFRP bars. The test results indicated that the walls utilizing CFRP bars had small residual deformations and residual crack widths. Lower crack propagation height and larger concrete crushing region, bearing capacity and equivalent viscous damping coefficient (EVDC) could be observed with the increase of axial load ratios. The effects of stirrup forms on experimental results had a relation to the axial load ratio. When the axial load ratio was small, the shear walls with circular stirrups had better energy dissipation than that with rectangular stirrups at a given drift level, while the cumulative energy dissipation (CED) were similar. With the increase of axial load ratio, the walls exhibited similar energy dissipation at the same drift level, however, the shear walls with rectangular stirrups had larger CED.

Indium doping effect on the magnetic properties of Y-type hexaferrite Ba0.5Sr1.5Zn2(Fe1-xInx)12O22

Min Zhang,Lihua Yin,Qiangchun Liu,Zhenfa Zi,Jianming Dai,Yuping Sun 한국물리학회 2018 Current Applied Physics Vol.18 No.9

The effect of indium doping on structural and magnetic properties of Y-type hexaferrite Ba0.5Sr1.5Zn2(Fe1- xInx)12O22 (x=0, 0.02, 0.04, 0.06, 0.08 and 0.1) prepared by the solid state reaction method was investigated. The Rietveld refinement method was used to analyze the X-ray diffraction patterns. The magnetic transition temperatures associated with the proper-screw spin phase to the collinear ferrimagnetic spin phase transition can be efficiently modulated by varying indium content. The magnetic transition temperature increases to a maximum with indium content x=0.04 and then decreases with x, suggesting the possibility that electrically controlled magnetization reversal can be can be effectively tailored by varying indium content. The saturation magnetization at room temperature was decreased as increasing indium content, which can be explained as the metal ions occupation. It is worthy to note that the coercivity of In-doped samples was decreased drastically compared that of undoped sample, which is probably resulted from the reduction in anisotropy field with substitution of In3+ for Fe3+. The In-doped hexaferrite Ba0.5Sr1.5Zn2(Fe1-xInx)12O22 may be potential candidates for application in magnetoelectric devices.

Magnetic properties and enhanced thermoelectric performance in Cu-doped Ca3Co2O6 single crystals

Jiyue Song,Bangchuan Zhao,Yanan Huang,Yanfeng Qin,Wenhai Song,Yuping Sun 한국물리학회 2017 Current Applied Physics Vol.17 No.5

The effect of Cu doping on the structural, magnetic, electrical and thermal transport properties of Ca3Co2- xCuxO6 single crystals has been investigated systematically. Based on the analysis of the structural parameter and x-ray photoelectron spectroscopy spectra, the valence state of Cu is considered to be þ2. All samples undergo a long-range spin density wave (SDW) transition at TN and a glass-like magnetic transition at Tf with decreasing temperature. Both TN and Tf decrease monotonously with increasing Cudoping content. A series of magnetization steps can be observed in the M(H) curve of Ca3Co2O6, and the magnetization steps are sensitive to the sample cooling magnetic field and Cu doping content x. With the increase of x, the resistivity along c-axis decreases while the thermopower increases. As a result, the figure of merit (ZT) increases considerably and the room-temperature ZT value of the sample with x ¼ 0.6 is nearly 60 times larger than that of the un-doped crystal.