Fabrication and properties of machinable SiC/h-BN Nano-composites

Hai-yun Jin,Nai-kui Gao,Zong-ren Peng,Guan-jun Qiao,Ji-qiang Gao 한양대학교 세라믹연구소 2008 Journal of Ceramic Processing Research Vol.9 No.6

SiC/BN ceramic nano-composites powders were synthesized by an in-situ recation method and the composites were sintered by hot pressing in a N2 atmosphere. The microstructure, secondary phase and grain boundaries were characterized using a range of analytical techniques including TEM, SEM and XRD. The mechanical properties were determined, when the BN content is increaed because the nano-sized h-BN crystals were homogeneously dispersed around the SiC grains of the matrix, the fracture strength of the nano-composites decreased more slowly than that of the SiC/h-BN micro-composites, but the hardness of the composites decreased sharply and the machinability properites were improved noticeably. SiC/BN ceramic nano-composites powders were synthesized by an in-situ recation method and the composites were sintered by hot pressing in a N2 atmosphere. The microstructure, secondary phase and grain boundaries were characterized using a range of analytical techniques including TEM, SEM and XRD. The mechanical properties were determined, when the BN content is increaed because the nano-sized h-BN crystals were homogeneously dispersed around the SiC grains of the matrix, the fracture strength of the nano-composites decreased more slowly than that of the SiC/h-BN micro-composites, but the hardness of the composites decreased sharply and the machinability properites were improved noticeably.

Corrosion behavior and creepage discharze character for machinable AlN/h-BN ceramic composites

Hai-yun Jin,Bo He,Nai-kui Gao,Zong-ren Peng,Ji-qiang Gao 한양대학교 세라믹연구소 2008 Journal of Ceramic Processing Research Vol.9 No.5

AlN particles coated with nano-BN were synthesized. The AlN/BN ceramic composites were sintered by Plasma Active Sintering (PAS). Because the nano-BN crystals were homogeneously dispersed around the AlN grains of the matrix, the chemical corrosion resistance of AlN/nano-sized h-BN ceramic composites was higher than that of AlN/micro-sized h-BN ceramic composites and monolithic AlN ceramics. Due to the better hydrophobic property of h-BN, the AlN/BN composites had a better hydrophobic property than the monolithic AlN ceramic, at the same time, because of the homogeneous dispersion of the nano-BN, the creepage discharze voltage of AlN/nano-sized BN composites was the highest. AlN particles coated with nano-BN were synthesized. The AlN/BN ceramic composites were sintered by Plasma Active Sintering (PAS). Because the nano-BN crystals were homogeneously dispersed around the AlN grains of the matrix, the chemical corrosion resistance of AlN/nano-sized h-BN ceramic composites was higher than that of AlN/micro-sized h-BN ceramic composites and monolithic AlN ceramics. Due to the better hydrophobic property of h-BN, the AlN/BN composites had a better hydrophobic property than the monolithic AlN ceramic, at the same time, because of the homogeneous dispersion of the nano-BN, the creepage discharze voltage of AlN/nano-sized BN composites was the highest.

Association Between EGF, TGF-β1 and TNF-α Gene Polymorphisms and Hepatocellular Carcinoma

Shi, Hai-Zhou,Ren, Peng,Lu, Qing-Jun,Niedrgethmnn, Marco,Wu, Guo-Yang Asian Pacific Journal of Cancer Prevention 2012 Asian Pacific journal of cancer prevention Vol.13 No.12

Introduction: Up to present, EGF $61^*A$/G, TGF-${\beta}1$-$509^*T$/C and TNF-${\alpha}$-$308^*A$/G gene polymorphisms have been analysed in other cancer entities than hepatocellular carcinoma (HCC). We here investigated the frequency of these gene polymorphisms among HCC patients. Materials and Methods: A total of 73 HCC patients and 117 cancer-free healthy people were recruited at the Surgical Department of Zhongshan Hospital. Genomic DNA was isolated from peripheral blood and gene polymorphisms were analyzed by PCR-RFLP. Results: The distribution of EGF $61^*G$/G homozygotes among HCC patients was more frequent than that in the control group (24.7% vs 11.1%, OR=2.618, 95%CI=1.195-5.738). In parallel, the frequency of the "G" allele in the HCC patient group was also higher than that in the control group (45.9% vs 33.3%, OR= 1.696, 95%CI=1.110-2.592). No difference could be found for the TGF-${\beta}1$-509 and TNF-${\alpha}$-308 genotypes. Conclusion: EGF $61^*G$/G genotype and G allele are significantly increased among patients with HCC. TGF-${\beta}1$-$509^*T$/C and TNF-${\alpha}$-$308^*A$/G gene polymorphisms are not related to this cancer entity.

Theoretical analysis of Y-shape bridge and application

Lu Peng-zhen,Zhang Jun-ping,Zhao Ren-da,Huang Hai-yun 국제구조공학회 2009 Structural Engineering and Mechanics, An Int'l Jou Vol.31 No.2

Mechanic behavior of Y-shape thin-walled box girder bridge structure is complex, so one can not exactly hold the mechanical behavior of the Y-shape thin-walled box girder bridge structure through general calculation theory and analytical method. To hold the mechanical behavior better, based on elementary beam theory, by increasing the degree of freedom analytical method, taking account of restrained torsiondistortion angledistortion warp and shearing lag effect at the same time, authors obtain a thin-walled box beam analytical element of 10 degrees of freedom of every node, derive stiffness matrix of the element, and code a finite element procedure. In addition, authors combine the obtained procedure with spatial grillage analytical method, meanwhile, they build a new analytical method that is the spatial thin-walled box girder element grillage analysis method. In order to validate the precision of the obtained analysis method, authors analyze a type Y-shape thin-walled box girder bridge structure according to the elementary beam theory analytical method, the shell theory analytical method and the spatial thin-walled box girder element grillage analysis method respectively. At last, authors test a type Y-shape thin-walled box girder bridge structure. Comparisons of the results of theory analysis with the experimental text show that the spatial thin-walled box girder element grillage analysis method is simple and exact. The research results are helpful for the knowledge of the mechanics property of these Y-shape thin-walled box girder bridge structures.

Polyvinylidene Fluoride Electrospun Fibers Loaded TiO2 for Photocatalytic Degradation and Oil/Water Separation

Fei Sun,Hai-Tao Ren,Shih-Yu Huang,Ting-Ting Li,Hao-Kai Peng,Qi Lin,Ching-Wen Lou,Jia-Horng Lin 한국섬유공학회 2020 Fibers and polymers Vol.21 No.7

In this study, electrospun polyvinylidene fluoride (PVDF)-based nanofibrous membranes embedding TiO2 wereprepared and used for photocatalytic degradation and oil/water separation. The nanofibrous membranes were characterizedby scanning electron microscopy (SEM), transmission electronic microscope (TEM), X-ray diffraction (XRD), Fouriertransform infrared spectroscopy (FTIR) spectroscopy, thermal performance analysis, and oil/water separation analysis. Andthe degradation of rhodamine B dye was also investigated. Results showed that the fiber diameter and thermal stability of themembranes decreased with the increasing of TiO2. Meanwhile, the fiber surface roughness and specific surface areaincreased. The analysis of TEM, XRD and FTIR indicated that TiO2 existed in the PVDF membranes. When the TiO2 contentwas 12 %, the fiber diameter of the membranes was about 110 nm, and the photocatalytic degradation of rhodamine B dyeefficiency was up to 97 %. The reaction rate constant was 0.02057 min-1. At 0.01 MPa vacuum, oil separated from watereffectively, which proves that separation can be easily conducted with a low energy cost. Thus, the prepared membranes havea very high application prospect in the purification of reclaimed water and separation of oil and water.

An Optimized PI Controller Design for Three Phase PFC Converters Based on Multi-Objective Chaotic Particle Swarm Optimization

Guo, Xin,Ren, Hai-Peng,Liu, Ding The Korean Institute of Power Electronics 2016 JOURNAL OF POWER ELECTRONICS Vol.16 No.2

The compound active clamp zero voltage soft switching (CACZVS) three-phase power factor correction (PFC) converter has many advantages, such as high efficiency, high power factor, bi-directional energy flow, and soft switching of all the switches. Triple closed-loop PI controllers are used for the three-phase power factor correction converter. The control objectives of the converter include a fast transient response, high accuracy, and unity power factor. There are six parameters of the controllers that need to be tuned in order to obtain multi-objective optimization. However, six of the parameters are mutually dependent for the objectives. This is beyond the scope of the traditional experience based PI parameters tuning method. In this paper, an improved chaotic particle swarm optimization (CPSO) method has been proposed to optimize the controller parameters. In the proposed method, multi-dimensional chaotic sequences generated by spatiotemporal chaos map are used as initial particles to get a better initial distribution and to avoid local minimums. Pareto optimal solutions are also used to avoid the weight selection difficulty of the multi-objectives. Simulation and experiment results show the effectiveness and superiority of the proposed method.

An Optimized PI Controller Design for Three Phase PFC Converters Based on Multi-Objective Chaotic Particle Swarm Optimization

Xin Guo,Hai-Peng Ren,Ding Liu 전력전자학회 2016 JOURNAL OF POWER ELECTRONICS Vol.16 No.2

The compound active clamp zero voltage soft switching (CACZVS) three-phase power factor correction (PFC) converter has many advantages, such as high efficiency, high power factor, bi-directional energy flow, and soft switching of all the switches. Triple closed-loop PI controllers are used for the three-phase power factor correction converter. The control objectives of the converter include a fast transient response, high accuracy, and unity power factor. There are six parameters of the controllers that need to be tuned in order to obtain multi-objective optimization. However, six of the parameters are mutually dependent for the objectives. This is beyond the scope of the traditional experience based PI parameters tuning method. In this paper, an improved chaotic particle swarm optimization (CPSO) method has been proposed to optimize the controller parameters. In the proposed method, multi-dimensional chaotic sequences generated by spatiotemporal chaos map are used as initial particles to get a better initial distribution and to avoid local minimums. Pareto optimal solutions are also used to avoid the weight selection difficulty of the multi-objectives. Simulation and experiment results show the effectiveness and superiority of the proposed method.

Interval Observer-based Robust Trajectory Tracking Control for Quadrotor Unmanned Aerial Vehicle

Kun Yan,Jing-Rong Zhang,Hai-Peng Ren 제어·로봇·시스템학회 2024 International Journal of Control, Automation, and Vol.22 No.1

In this work, a robust trajectory tracking control strategy is developed for the quadrotor unmanned aerial vehicle (QUAV) with unknown external disturbance. The nonlinear dynamic model of QUAV is established. Different from the traditional disturbance observer and adaptive estimation method, this paper adopts the interval observer technique to approximate the upper and lower bounds of the unknown disturbance. In this way, the proposed interval observer can cover its all possible values and show its scope in real time, especially before the disturbance error estimation converges. Combining with the backstepping approach, a robust tracking control approach is proposed to ensure that the desired trajectory can be successfully followed. Finally, comparative numerical simulation results are provided to evaluate the presented robust tracking controller.

Molecular Beam Epitaxy of Highly Crystalline Monolayer Molybdenum Disulfide on Hexagonal Boron Nitride

Fu, Deyi,Zhao, Xiaoxu,Zhang, Yu-Yang,Li, Linjun,Xu, Hai,Jang, A-Rang,Yoon, Seong In,Song, Peng,Poh, Sock Mui,Ren, Tianhua,Ding, Zijing,Fu, Wei,Shin, Tae Joo,Shin, Hyeon Suk,Pantelides, Sokrates T.,Zho American Chemical Society 2017 JOURNAL OF THE AMERICAN CHEMICAL SOCIETY - Vol.139 No.27

<P>Atomically thin molybdenum disulfide (MoS2), a direct-band-gap semiconductor, is promising for applications in electronics and optoelectronics, but the scalable synthesis of highly crystalline film remains challenging. Here we report the successful epitaxial growth of a continuous, uniform, highly crystalline monolayer MoS2 film on hexagonal boron nitride (h-BN) by molecular beam epitaxy. Atomic force microscopy and electron microscopy studies reveal that MoS2 grown on h-BN primarily consists of two types of nucleation grains (0 aligned and 60 degrees antialigned domains). By adopting a high growth temperature and ultralow precursor flux, the formation of 60 degrees antialigned grains is largely suppressed. The resulting perfectly aligned grains merge seamlessly into a highly crystalline film. Large-scale monolayer MoS2 film can be grown on a 2 in. h-BN/sapphire wafer, for which surface morphology and Raman mapping confirm good spatial uniformity. Our study represents a significant step in the scalable synthesis of highly crystalline MoS2 films on atomically flat surfaces and paves the way to large-scale applications.</P>

ZD1839 and Cisplatin Alone or in Combination for Treatment of a Nasopharyngeal Carcinoma Cell Line and Xenografts

Gu, Wei-Guang,Huang, Yan,Yuan, Zhong-Yu,Peng, Rou-Jun,Luo, Hai-Tao,He, Zhi-Ren,Wang, Shu-Sen Asian Pacific Journal of Cancer Prevention 2013 Asian Pacific journal of cancer prevention Vol.14 No.3

This study evaluated the effects of ZD1839, an orally active, selective epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor, on nasopharyngeal carcinoma (NPC) both in vitro and in vivo. Influence of ZD1839 alone or combined with cisplatin on the NPC cell line CNE2 was detected by MTT assay with flow cytometry assessment of cell cycle distribution and apoptosis rates. Nude mice NPC xenografts were also used to evaluate the effects of ZD1839 alone or combined with cisplatin. The Student's t test evaluated statistical significance. ZD1839 alone or combined with cisplatin inhibited CNE2 cell line proliferation. ZD1839 induced CNE2 cell cycle arrest in the G1 phase, and higher concentrations induced apoptosis. Xenograft tumors were significantly smaller when treated with 200 mg/kg ZD1839, cisplatin, or cisplatin combined with 100 mg/kg ZD1839 than untreated controls. ZD1839 (200 mg/kg) alone showed good tumor inhibition effects, reduction of tumor weights, and smaller tumor volume without loss of body weight. ZD1839 (200 mg/kg) might provide a good and effective therapeutic reagent for NPC.