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Yuan Lu,Ji-Qiang Gao,Jian-feng Yang 한양대학교 세라믹연구소 2008 Journal of Ceramic Processing Research Vol.9 No.6
In this paper, porous Si3N4 ceramics were fabricated by carbothermal reduction between silicon dioxide and carbon [1]. The influences of α-Si3N4 seeds and sintering additives on the microstructure and mechanical properties of porous Si3N4 ceremics were investigated. XRD analysis proved the complete formation of a single-phase β-Si3N4. SEM analysis showed that the resultant porous Si3N4 ceramics had a fine microstructure and a uniform pore structure. The sintered sample with Lu2O3 as sintering additive showed finer, higher aspect ratio β-Si3N4 grains. The addition of Eu2O3 accelerated the densification of porous Si3N4 ceramics, decreased the porosity and increased the flexural strength. The addition of α-Si3N4 seeds accelerated the formation of the α-Si3N4 phase at a low temperature and the α-β phase transformation process at a high temperature. With an increase in the α-Si3N4 seeds content, the porosity decreased, and the flexural strength increased accordingly. In this paper, porous Si3N4 ceramics were fabricated by carbothermal reduction between silicon dioxide and carbon [1]. The influences of α-Si3N4 seeds and sintering additives on the microstructure and mechanical properties of porous Si3N4 ceremics were investigated. XRD analysis proved the complete formation of a single-phase β-Si3N4. SEM analysis showed that the resultant porous Si3N4 ceramics had a fine microstructure and a uniform pore structure. The sintered sample with Lu2O3 as sintering additive showed finer, higher aspect ratio β-Si3N4 grains. The addition of Eu2O3 accelerated the densification of porous Si3N4 ceramics, decreased the porosity and increased the flexural strength. The addition of α-Si3N4 seeds accelerated the formation of the α-Si3N4 phase at a low temperature and the α-β phase transformation process at a high temperature. With an increase in the α-Si3N4 seeds content, the porosity decreased, and the flexural strength increased accordingly.
Luís F. P. Silva,Valter J. S. Leite,Eugênio B. Castelan,Gang Feng 제어·로봇·시스템학회 2018 International Journal of Control, Automation, and Vol.16 No.3
We propose convex conditions for stabilization of nonlinear discrete-time systems with time-varying delay in states through a fuzzy Takagi-Sugeno (T-S) modeling. These conditions are developed from a fuzzy Lyapunov-Krasovskii function and they are formulated in terms of linear matrix inequalities (LMIs). The results can be applied to a class of nonlinear systems that can be exactly represented by T-S fuzzy models inside a specific region called the region of validity. As a consequence, we need to provide an estimate of the set of safe initial conditions called the region of attraction such that the closed-loop trajectories starting in this set are assured to remain in the region of validity and to converge asymptotically to the origin. The estimate of the region of attraction is done with the aid of two sets: one dealing with the current state, and the other concerning the delayed states. Then, we can obtain the feedback fuzzy control law depending on the current state, xk, and the maximum delayed state vector, xk-d. It is shown that such a control law can locally stabilize the nonlinear discrete-time system at the origin. We also develop convex optimization procedures for the computation of the fuzzy control gains that maximize the estimates of the region of attraction. We present two examples to demonstrate the efficiency of the developed approach and to compare it with other approaches in the literature.
Lu, Feng-Bin,Chen, Da-Zhi,Chen, Lu,Hu, En-De,Wu, Jin-Lu,Li, Hui,Gong, Yue-Wen,Lin, Zhuo,Wang, Xiao-Dong,Li, Ji,Jin, Xiao-Ya,Xu, Lan-Man,Chen, Yong-Ping Korean Society for Molecular and Cellular Biology 2019 Molecules and cells Vol.42 No.12
MicroRNA-223-3p (miR-223-3p) is one of the potential microRNAs that have been shown to alleviate inflammatory responses in pre-clinical investigations and is highly encased in exosomes derived from bone mesenchymal stem cells (MSC-exosomes). MSC-exosomes are able to function as carriers to deliver microRNAs into cells. Autoimmune hepatitis is one of the challenging liver diseases with no effective treatment other than steroid hormones. Here, we examined whether MSC-exosomes can transfer miR-223-3p to treat autoimmune hepatitis in an experimental model. We found that MSC-exosomes were successfully incorporated with miR-223-3p and delivered miR-223-3p into macrophages. Moreover, there was no toxic effect of exosomes on the macrophages. Furthermore, treatments of either exosomes or exosomes with miR-223-3p successfully attenuated inflammatory responses in the liver of autoimmune hepatitis and inflammatory cytokine release in both the liver and macrophages. The mechanism may be related to the regulation of miR-223-3p level and STAT3 expression in the liver and macrophages. These results suggest that MSC-exosomes can be used to deliver miR-223-3p for the treatment of autoimmune hepatitis.
Inverse Analysis of Inconel 718 Laser-Assisted Milling to Achieve Machined Surface Roughness
Yixuan Feng,Tsung-Pin Hung,Yu-Ting Lu,Yu-Fu Lin,Fu-Chuan Hsu,Chiu-Feng Lin,Ying-Cheng Lu,Xiaohong Lu,Steven Y. Liang 한국정밀공학회 2018 International Journal of Precision Engineering and Vol.19 No.11
This manuscript proposes an inverse analysis method for the machined surface roughness in laser-assisted milling on Inconel 718. The method solves the forward problem considering the tool profile and the elastic recovery of machined surface and applies the variance-based recursive method to guide the updating mechanism of process parameters to match the measurements. Subsequently, the inverse analysis identifies four process parameters of feed per tooth, tool tip radius, minimum cutting thickness, and tool tip angle, and finds the optimal solution for target performance, the surface roughness. The measurements are collected under the single beam coaxial laser-assisted milling spindle. The proposed modified Kalman filter algorithm introduces the gain coefficient G when updating the process parameters to improve robustness and accuracy. The inverse analysis is conducted on all measurements, and the average error of target performance is 0.460% when the laser is on and 0.394% when the laser is off. The average difference of process parameters is less than 5%, and the selection process is done in 50 loops within a minute. Therefore, the proposed inverse analysis model is robust, adaptive to different initial guesses and measurements, highly accurate, and saves computation time.
Prevalence of Drug Resistance-Associated Gene Mutations in Plasmodium vivax in Central China
Feng Lu,Bo Wang,Jun Cao,Jetsumon Sattabongkot,Huayun Zhou,Kwonkee Kim,Qi Gao,Eun-Taek Han 대한기생충학열대의학회 2012 The Korean Journal of Parasitology Vol.50 No.4
Resistance of Plasmodium spp. to anti-malarial drugs is the primary obstacle in the fight against malaria, and molecular markers for the drug resistance have been applied as an adjunct in the surveillance of the resistance. In this study, we investigated the prevalence of mutations in pvmdr1, pvcrt-o, pvdhfr, and pvdhps genes in temperate-zone P. vivax parasites from central China. A total of 26 isolates were selected, including 8 which were previously shown to have a lower susceptibility to chloroquine in vitro. For pvmdr1, pvcrt-o, and pvdhps genes, no resistance-conferring mutations were discovered. However, a highly prevalent (69.2%), single-point mutation (S117N) was found in pvdhfr gene. In addition, tandem repeat polymorphisms existed in pvdhfr and pvdhps genes, which warranted further studies in relation to the parasite resistance to antifolate drugs. The study further suggests that P. vivax populations in central China may still be relatively susceptible to chloroquine and sulfadoxine-pyrimethamine.
Free vibration of orthotropic functionally graded beams with various end conditions
Lu, Chao-Feng,Chen, W.Q. Techno-Press 2005 Structural Engineering and Mechanics, An Int'l Jou Vol.20 No.4
Free vibration of orthotropic functionally graded beams, whose material properties can vary arbitrarily along the thickness direction, is investigated based on the two-dimensional theory of elasticity. A hybrid state-space/differential quadrature method is employed along with an approximate laminate model, which allows us to obtain the semi-analytical solution easily. With the introduction of continuity conditions at each fictitious interface and boundary conditions at the top and bottom surfaces, the frequency equation for an inhomogeneous beam is derived. A completely exact solution of an FGM beam with material constants varying in exponential way through the thickness is also presented, which serves a benchmark to verify the present method. Numerical results are performed and discussed.
Lu, Feng,Ahmed, Md Atique,Xu, Simin,Xu, Sui,Han, Jin-Hee,Liu, Qianyan,Chen, Jing,Zhu, Guoding,Zhou, Huayun,Cao, Jun,Han, Eun-Taek ELSEVIER 2019 INFECTION GENETICS AND EVOLUTION Vol.70 No.-
<P><B>Abstract</B></P> <P>Imported malaria due to <I>Plasmodium ovale curtisi</I> and <I>P</I>. <I>ovale wallikeri</I> infections from African countries has increased recently (2011–2014) in Chinese travelers. We report novel genotypes, their prevalence and the predominant haplotypes of <I>P</I>. <I>ovale curtisi</I> and <I>P</I>. <I>ovale wallikeri</I> circumsporozoite protein (CSP) from 20 African countries in Chinese travelers. These genotypes should be considered while designing a CSP-based vaccine against <I>P</I>. <I>ovale</I> malaria.</P> <P><B>Highlights</B></P> <P> <UL> <LI> This is the first to report the <I>csp</I> genotypes and their heterogeneity for <I>P. ovale curtisi</I> and <I>P. ovale wallikeri</I> parasites from African countries. </LI> <LI> Ten <I>csp</I> genotypes of <I>P</I>. <I>ovale curtisi</I> and 13 <I>csp</I> genotypes of <I>P</I>. <I>ovale wallikeri</I> based on the arrangement of central repeat motifs were found. </LI> <LI> Fifteen <I>csp</I> haplotypes of <I>P</I>. <I>ovale curtisi</I> and 10 <I>csp</I> haplotypes of <I>P</I>. <I>ovale wallikeri</I> on central repeat motifs were identified. </LI> <LI> These genotypes should be considered while designing a CSP-based vaccine against <I>P</I>. <I>ovale</I> malaria. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
Nonlinear tribo-dynamic model of helicopter mid-reducer system under light loss of lubrication
Feng-xia Lu,Xuechen Cao,He-yun Bao,Rupeng Zhu 대한기계학회 2022 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.36 No.11
When the helicopter tail transmission system loses oil due to damage, the system needs to persist for 30 minutes. Therefore, the nonlinear tribo-dynamics model of the helicopter intermediate reducer (HIR) is established, which is coupled with the loss of oil lubrication. To simulate condition of the HIR system under the loss of lubrication (LOL), this study begins by establishing a complete HIR system CFD model, and analyse the lubrication of the gear tooth surface and the oil churning/windage under different lubrication conditions. Then, a coupled model based on the result of the CFD is proposed to calculate the coefficient of friction (COF) under the condition of light loss of lubrication (LLOL). The results show that COF gradually decreases first and then increases rapidly.