A Low-Cost Nano/Micro Structured-Silicon-MWCNTs from Nano-Silica for Lithium Storage

Xuejiao Feng,Tengda Ding,Hongmin Cui,Nanfu Yan,Fei Wang 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2016 NANO Vol.11 No.3

Despite the fact that silicon material can be synthesized from various sources, deriving them from silica resources is of strategic significance for the industrial processing. Here a low-cost nano/ micro structure of Si–CNT was derived from nano-SiO2 and multiwall carbon nanotubes (MWCNTs) with simple methods. By employing table salt (NaCl) as a heat scavenger for the magnesiothermic reduction, the nano/micro structure of the material was remained effective. Comparing to ball milling, a combination of SiO2, MWCNTs and NaCl by spray drying achieved the long cycle life for Si–CNT composite. This material presented a stable capacity above 968.1 mAh g-1 with excellent capacity retention of 85.4% at the 150th cycle versus the 2nd one. The Si nanoparticles, very small particle size in 10–20 nm, homogenously dispersed in electronically conductive network of MWCNTS, which accommodate the volume change of Si and reinforce highly conductivity of the Si–CNT composite during repeated cycles. Combined with its low-cost and up-scaling technologies, Si–CNT composite is a promising anode material in rechargeable lithium batteries with high electrochemical performance.

Photoluminescence properties and concentration quenching of Dy3+ doped YAG phosphors for domestic lighting

Xuejiao Niu 한양대학교 세라믹연구소 2015 Journal of Ceramic Processing Research Vol.16 No.5

Y3Al5O12 : xDy3+ (x = 0.02, 0.04, 0.06, 0.08, 0.1) phosphors were synthesized by sol-gel method. The strongest excitation peak at 352 nm was attributed to the 6 H15/2→ 6 P7/2 transition of Dy3+. Under the excitation of 352 nm, the emission spectra showed three peaks at about 483 nm (4 F9/2→ 6 H15/2), 582 nm (4 F9/2→ 6 H13/2) and 669 nm (4 F9/26→ H11/2), respectively. The critical quenching concentration of Dy3+ in YAG : Dy3+ phosphors was about 6mol%, which was associated to the cross-relaxation processes. The CIE chromatic coordinate of YAG : 0.02Dy3+ phosphor was located at (0.385, 0.384) under 352 nm excitation, which was close to the National standard white light chromaticity (0.380, 0.380) for Energy Saving Lamp. Thus, white LED based on an UV LED chip and YAG : Dy phosphor has potential application for domestic lighting

Design and Prediction of Three Dimensional Flows in a Low Speed Highly Loaded Axial Flow Fan

Xuejiao Liu,Liu Chen,Ren Dai,Ailing Yang 한국유체기계학회 2013 International journal of fluid machinery and syste Vol.6 No.2

This paper describes the design to increase the blade loading factor of a low speed axial flow fan from normal 0.42 to highly loaded 0.55. A three-dimensional viscous solver is used to model the flows in the highly-loaded and normal loaded stages over its operation range. At the design point operation the static pressure rise can be increased by 20 percent with a deficit of efficiency by 0.3 percent. In the highly loaded fan stage, the rotor hub flow stalls, and separation vortex extends over the rotor hub region. The backflow, which occurs along the stator hub-suction surface, changes the exit flow from the prescribed axial direction. Results in this paper confirm that the limitation of the two dimensional diffusion does not affect primarily on the fan's performance. Highly loaded fan may have actually better performance than its two dimensional design. Three dimensional designing approaches may lead to better highly loaded fan with controlled rotor hub stall.

Ontology-based Privacy Preserving Digital Forensics Framework

Xuejiao Wan,Jingsha He,Na Huang,Yonghao Mai 보안공학연구지원센터 2015 International Journal of Security and Its Applicat Vol.9 No.4

Along with the rapid growth of the number of intelligent mobile devices as well as applications in recent years owing to the development of network information and telecommunication technologies, personal privacy faces a unprecedented level of risk. This seems to be especially inevitable in digital forensic investigations. Consequently, there is an urgent need to balance the desire for privacy preservation and information extraction in the process of digital forensic investigations. This paper focuses on the issues related to personal privacy protection by proposing a digital forensics framework based on the theory of ontology. In addition to introducing the basic concepts that will lead to the establishment of the framework, we will also present some experiments that can be viewed as the demonstration of the effectiveness of the framework in privacy protection in the process of digital forensic investigations. The framework can thus serve as the foundation in the design of digital forensic tools and systems that can respect the privacy of individuals.

Performance investigation of MHD micro-mixers with different pumping capabilities for two different miscible fluids

Xuejiao Xiao,김창녕 한국공업화학회 2018 Journal of Industrial and Engineering Chemistry Vol.60 No.-

In this study, a magnetohydrodynamic (MHD) micro-mixer with differential pumping capabilities for two different miscible fluids is newly proposed and numerically investigated. Lorentz-force can be created with different potentials applied to different electrodes, producing a differential pumping for the two fluids, and inducing a cross-sectional fluid circulation for mixing. The results show that the micro-mixer proposed can achieve high mixing performance for electrolytes. Here, the effect of the ratio of the potential difference in pumping section on the ratio of the mass flow rate of the two fluids is obtained in the form of an exponential function.

Electrically Conductive Graphene-Based Biodegradable Polymer Composite Films with High Thermal Stability and Flexibility

Xuejiao Liu,Qinfeng Zou,Tianhao Wang,Liping Zhang 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2018 NANO Vol.13 No.3

Cellulose nanofibril (CNF) and graphene (GR) powder were added into polylactic acid (PLA)/ polypyrrole (PPy) composite films via a low-cost, eco-friendly, low-temperature, and in-situ polymerization synthesis, which obtain novel flexible and conductive polylacticacid-cellulose nanofibril-graphene/polypyrrole (PLA–CNF–GR/PPy) composite films. The CNF was embedded in the PLA matrix to enhance the mechanical properties. Remarkably, when a few GR (1%) powder was added, the tensile strength of composite films increased by 5.6%, respectively, compared with pure PLA–CNF, and increased by 17.6% compared with the PLA. The GR and CNF had a positive influence on mechanical properties of composite films. In addition, the PLA–CNF–GR/PPy composite films exhibited many unique properties when GR powder was introduced, including high thermal stability, and especially electrical conductivity. The electrical conductivity of the PLA–CNF–GR/PPy composite films increased from 0.12 to 1.06 S/cm as the content of GR powder increased from 0 to 10%. The PLA–CNF–GR-10/PPy also demonstrated excellent flexible stability, only 7.5% deviation after over 100 bending cycles. Furthermore, we designed and found that the exploration of a flexible solid-state supercapacitor assembled with PLA–CNF–GR-10/PPy composite electrodes had a capacitance of 30 F/g at a current density of 0.5 A/g. Although it was not quite as prominent as the capacitance, it provided an innovative means for preparing the conductive composite films. Based on these advantages the PLA–CNF–GR/PPy could be considered as sensors, flexible electrodes, and flexible displays. It also opens a new field of potential applications of biodegradable materials.

Numerical analysis of an MHD micro-device with simultaneous mixing and pumping capability

Xuejiao Xiao,김창녕 한국공업화학회 2016 Journal of Industrial and Engineering Chemistry Vol.38 No.-

In this study, a new magneto-hydrodynamic (MHD) micro-device with simultaneous mixing andpumping capability is proposed, and a numerical investigation for the performance of the device isperformed. The present MHD micro-device utilizes the arrays of electrodes deposited on duct walls. Byjudiciously applying different potentials to different electrode pairs, the Lorentz-force can be created,directing the liquid to move in a desired path for pumping without a need of separate pumps, andsimultaneously inducing complex flows for mixing. The results show that the micro-device proposed inthis study can achieve highly-efficient, simultaneous mixing and pumping for electrolytes.

Effect of the magnetic field direction on the mass-imbalance of MHD flows in a multi-channel conduit with spatially non-uniform electric conductivity

Xuejiao Xiao,Shangjing Yang,김창녕 대한기계학회 2020 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.34 No.9

In this study, numerically analyzed is the effect of the orientation of the applied transverse magnetic field on the mass-imbalance of MHD flows in a multi-channel conduit consisting of three parallel channels with spatially non-uniform electric conductivity, by using CFX. In the multi-channel conduit, co-flows are driven by the constant pressure gradient in the three channels so that the mass-imbalance among the three channels may be observed in the above situations. Here, the mechanism leading to the mass flow imbalance caused by the orientation of magnetic field and by the spatial difference in the electric conductivity is discussed specifically. The results show that when the channels have spatially different electric conductivity the mass flow imbalance becomes more significant with an increasing of the angle of the applied magnetic field with respect to the plane parallel to the three channels (α).

CRM1 inhibitor S109 suppresses cell proliferation and induces cell cycle arrest in renal cancer cells

Xuejiao Liu,Yulong Chong,Huize Liu,Yan Han,Mingshan Niu 대한생리학회-대한약리학회 2016 The Korean Journal of Physiology & Pharmacology Vol.20 No.2

Abnormal localization of tumor suppressor proteins is a common feature of renal cancer. Nuclear export of these tumor suppressor proteins is mediated by chromosome region maintenance-1 (CRM1). Here, we investigated the antitumor effects of a novel reversible inhibitor of CRM1 on renal cancer cells. We found that S109 inhibits the CRM1-mediated nuclear export of RanBP1 and reduces protein levels of CRM1. Furthermore, the inhibitory effect of S109 on CRM1 is reversible. Our data demonstrated that S109 significantly inhibits proliferation and colony formation of renal cancer cells. Cell cycle assay showed that S109 induced G1-phase arrest, followed by the reduction of Cyclin D1 and increased expression of p53 and p21. We also found that S109 induces nuclear accumulation of tumor suppressor proteins, Foxo1 and p27. Most importantly, mutation of CRM1 at Cys528 position abolished the effects of S109. Taken together, our results indicate that CRM1 is a therapeutic target in renal cancer and the novel reversible CRM1 inhibitor S109 can act as a promising candidate for renal cancer therapy.

A Graph Neural Network for Spatiotemporal Dynamics Prediction

Xuejiao Li,He Li,Jongtae Lim,Jaesoo Yoo 한국콘텐츠학회 2023 한국콘텐츠학회 ICCC 논문집 Vol.2023 No.12