Pure Ultraviolet Emission from ZnO Quantum Dots-Based/GaN Heterojunction Diodes by MgO Interlayer

Cheng Chen,Renli Liang,Jingwen Chen,Jun Zhang,Shuai Wang,Chong Zhao,Wei Zhang,Jiangnan Dai,Changqing Chen 대한금속·재료학회 2017 ELECTRONIC MATERIALS LETTERS Vol.13 No.4

We demonstrate the fabrication and characterization of ZnO/GaNbasedheterojunction light-emitting diodes (LEDs) by using air-stableand solution-processable ZnO quantum dots (QDs) with a thin MgOinterlayer acting as an electron blocking layer (EBL). The ZnO QDs/MgO/p-GaN heterojunction can only display electroluminescence(EL) characteristic in reverse bias regime. Under sufficient reversebias, a fairly pure ultraviolet EL emission located at 370 nm derivingfrom near band edge of ZnO with a full width at half maximum(FWHM) of 8.3 nm had been obtained, while the deep-level emissionhad been almost totally suppressed. The EL origination andcorresponding carrier transport mechanisms were investigatedqualitatively in terms of photoluminescence (PL) results and energyband diagram.

Fabrication and Characterization of Vertically Aligned ZnO Nanorod Arrays via Inverted Monolayer Colloidal Crystals Mask

Cheng Chen,Taotao Ding,Zhiqiang Qi,Wei Zhang,Jun Zhang,Juan Xu,Jingwen Chen,Jiangnan Dai,Changqing Chen 대한금속·재료학회 2018 ELECTRONIC MATERIALS LETTERS Vol.14 No.4

The periodically ordered ZnO nanorod (NR) arrays have been successfully synthesized via a hydrothermal approach on thesilicon substrates by templating of the TiO2ring deriving from the polystyrene (PS) nanosphere monolayer colloidal crystals(MCC). With the inverted MCC mask, sol–gel-derived ZnO seeds could serve as the periodic nucleation positions for thesite-specific growth of ZnO NRs. The large-scale patterned arrays of single ZnO NR with good side-orientation can be readilyproduced. According to the experimental results, the as-integrated ZnO NR arrays showed an excellent crystal quality andoptical property, very suitable for optoelectronic applications such as stimulated emitters and ZnO photonic crystal devices.

Acupotomy for Lumbar disc herniation

Chen Xilin,Fu Xinyi,Luo Zhichao,Xin Wenshan,Wang Quangui,Lee Mira,Guo Changqing 대한침구의학회 2020 대한침구의학회지 Vol.37 No.3

Background: The aim of this study was to examine whether the effects of acupotomy therapy were beneficial for the treatment of protrusion of lumbar intervertebral disc. Methods: The number of patients (n = 80) were equally assigned into treatment group and control group. Treatment group was given acupotomy therapy twice a week, and control group was given acupuncture 3 times a week, for 4 weeks. The beneficial effect and changes in score of the Japan Orthopedic Association (JOA) for low back pain were observed. Results: Among 40 cases in the treatment group, there were 25 (62.5%) with an excellent effect, 13 (32.5%) with good effect, 1 (2.5%) with a medium effect and 1 (2.5%) with poor effect, with the total experiencing an excellent/good effect of 95.0%. Among 40 cases in the control group, there were 11 (27.5%) with an excellent effect, 17 (42.5%) with good effect, 10 (25.0%) with a medium effect, and 2 (5.0%) with poor effect, with an excellent/good rate of 70.0%. The result of the rank sum test showed Z = -4.923, p < 0.05 in the comparison, indicating a significantly better outcome following acupotomy compared with acupuncture. JOA scores increased in both groups after treatment (p < 0.05), which was more significant in the acupotomy treatment group (p < 0.05). Conclusion: Acupotomy therapy has a beneficial effect on protrusion of lumbar intervertebral disc.

A Transverse Load Sensor with Reconfigurable Measurement Accuracy Based on a Microwave Photonic Filter

Chen, Han,Li, Changqing,Min, Jing Optical Society of Korea 2018 Current Optics and Photonics Vol.2 No.6

We propose a transverse load sensor with reconfigurable measurement accuracy based on a microwave photonic filter in the $K_u$ band, incorporating a polarization-maintaining fiber Bragg grating. A prototype sensor with a reconfigurable measurement accuracy tuning range from 6.09 to 9.56 GHz/(N/mm), and corresponding minimal detectable load range from 0.0167 to 0.0263 N/mm, is experimentally demonstrated. The results illustrate that up to 40% manufacturing error in the grating length can be dynamically calibrated to the same corresponding measurement accuracy for the proposed transverse load sensor, by controlling the semiconductor optical amplifier's injection current in the range of 154 to 419 mA.

Antiproliferative Activities of Parthenolide and Golden Feverfew Extract Against Three Human Cancer Cell Lines

Changqing Wu,Feng Chen,James W. Rushing,Xi Wang,김현진,George Huang,Vivian Haley-Zitlin,Guoqing He 한국식품영양과학회 2006 Journal of medicinal food Vol.9 No.1

The medicinal herb feverfew [Tanacetum parthenium (L.) Schultz-Bip.] has long been used as a folk remedyfor the treatment of migraine and arthritis. Parthenolide, a sesquiterpene lactone, is considered to be the primary bioactivecompound in feverfew having anti-migraine, anti-tumor, and anti-inflammatory properties. In this study we determined, throughin vitrobioassays, the inhibitory activity of parthenolide and golden feverfew extract against two human breast cancer celllines (Hs605T and MCF-7) and one human cervical cancer cell line (SiHa). Feverfew ethanolic extract inhibited the growthof all three types of cancer cells with a half-effective concentration (EC50) of 1.5 mg/mL against Hs605T, 2.1 mg/mL againstMCF-7, and 0.6 mg/mL against SiHa. Among the tested constituents of feverfew (i.e., parthenolide, camphor, luteolin, andapigenin), parthenolide showed the highest inhibitory effect with an EC50 against Hs605T, MCF-7, and SiHa of 2.6 .g/mL,2.8 .g/mL, and 2.7 .g/mL, respectively. Interactions between parthenolide and flavonoids (apigenin and luteolin) in fever-few extract also were investigated to elucidate possible synergistic or antagonistic effects. The results revealed that apigeninand luteolin might have moderate to weak synergistic effects with parthenolide on the inhibition of cancer cell growth ofHs605T, MCF-7, and SiHa.

Analysis for Stress Characteristics and Structural Parameters Optimization in Orthotropic Steel Box Girders based on Fatigue Performance

Meiling Zhuang,Changqing Miao,Rongfeng Chen 대한토목학회 2019 KSCE Journal of Civil Engineering Vol.23 No.6

A fatigue design method for the orthotropic steel deck bridges is proposed. The stress characteristics of welded details are analyzed using the finite element method. Based on the fatigue performance, the structural parameters of the orthotropic steel decks (OSDs) are optimized using the combination BP (back propagation) neural network and genetic algorithms (GA). The calculated results demonstrate that the weld stresses at the deck plate-to-rib, deck plate-to-rib-to-diaphragm welded details are mainly bending stress while those at the rib-to-rib welded details are mainly membrane stress. The fatigue stress of each weld is deeply affected by the transverse and longitudinal direction positions. The local effect of stress distribution of all welded details is remarkable. The calculated results obtained using the proposed model are in good agreement with those obtained using ANSYS and the errors are within 5%. The optimal structural results are highly influenced by the applied wheel loadings, while the optimal results for the deck thickness and the U-rib opening size are highly influenced by temperature. Especially on the ordinary lane, temperature has a great effect on the fatigue performance for all welded details.

A Summary of Multicast Routing Algorithms in Wireless Mesh Networks

Liang Zhao,Changqing Gong,Xianwei Li,Guolong Chen 보안공학연구지원센터 2015 International Journal of Multimedia and Ubiquitous Vol.10 No.6

Wireless Mesh Network (WMN) presents us a key emerging technology which can construct the next generation wireless multi-hop network. It combines the advantages of both mobile ad-hoc network (MANET) and traditional fixed network. The applications of WMNs also attract significant industrial and academic attentions. As a vital function of network communication, multicast is normally applied to transmit data for high-definition video and gaming in WMNs. Therefore, the multicast routing algorithms are very important to the performance of group communication in WMNs. In this paper, we review a list of existing multicast routing algorithms in WMNs. Based on the findings, we also point out the open issues of multicast routing algorithms.

The Role of Kif4A in Doxorubicin-Induced Apoptosis in Breast Cancer Cells

Hui Wang,Changqing Lu,Qing Li,Jun Xie,Tongbing Chen,Yan Tan,Changping Wu,Jingting Jiang 한국분자세포생물학회 2014 Molecules and cells Vol.37 No.11

This study was to investigate the mechanism and role of Kif4A in doxorubicin-induced apoptosis in breast cancer. Using two human breast cancer cell lines MCF-7 (with wild-type p53) and MDA-MB-231 (with mutant p53), we quantitated the expression levels of kinesin super-family protein 4A (Kif4A) and poly (ADP-ribose) Polymerase-1 (PARP-1) by Western blot after doxorubicin treatment and examined the apoptosis by flow cytometry after treatment with doxorubicin and PARP-1 inhibitor, 3-Aminobenzamide (3-ABA). Our results showed that doxorubicin treatment could induce the apoptosis of MCF-7 and MDA-MB-231 cells, the down-regulation of Kif4A and upregulation of poly(ADP-ribose) (PAR). The activity of PARP-1 or PARP-1 activation was significantly elevated by doxorubicin treatment in dose- and time-dependent manners (P < 0.05), while doxorubicin treatment only slightly elevated the level of cleaved fragments of PARP-1 (P > 0.05). We further demonstrated that overexpression of Kif4A could reduce the level of PAR and significantly increase apoptosis. The effect of doxorubicin on apoptosis was more profound in MCF-7 cells compared with MDA-MB-231 cells (P < 0.05). Taken together, our results suggest that the novel role of Kif4A in doxorubicin-induced apoptosis in breast cancer cells is achieved by inhibiting the activity of PARP-1.

Performance Evaluations of Four MAF-Based PLL Algorithms for Grid-Synchronization of Three-Phase Grid-Connected PWM Inverters and DGs

Han, Yang,Luo, Mingyu,Chen, Changqing,Jiang, Aiting,Zhao, Xin,Guerrero, Josep M. The Korean Institute of Power Electronics 2016 JOURNAL OF POWER ELECTRONICS Vol.16 No.5

The moving average filter (MAF) is widely utilized to improve the disturbance rejection capability of phase-locked loops (PLLs). This is of vital significance for the grid-integration and stable operation of power electronic converters to electric power systems. However, the open-loop bandwidth is drastically reduced after incorporating a MAF into the PLL structure, which makes the dynamic response sluggish. To overcome this shortcoming, some new techniques have recently been proposed to improve the transient response of MAF-based PLLs. In this paper, a comprehensive performance comparison of advanced MAF-based PLL algorithms is presented. This comparison includes HPLL, MPLC-PLL, QT1-PLL, and DMAF-PLL. Various disturbances, such as grid voltage sag, voltage flicker, harmonics distortion, phase-angle and frequency jumps, DC offsets and noise, are considered to experimentally test the dynamic performances of these PLL algorithms. Finally, an improved positive sequence extraction method for a HPLL under the frequency jumps scenario is presented to compensate for the steady-state error caused by non-frequency adaptive DSC, and a satisfactory performance has been achieved.

Influence of Polyurethane Polymer on the Strength and Mechanical Behavior of Sand-root Composite

Jin Liu,Zhihao Chen,Zhaojun Zeng,Debi Prasanna Kanungo,Fan Bu,Yuxia Bai,Changqing Qi,Wei Qian 한국섬유공학회 2020 Fibers and polymers Vol.21 No.4

Vegetation has good application in slope stabilization, but its beneficial effects on reinforcing topsoil are generallylimited by the soil properties it was cultivated in. This study aims at evaluating the strength improvements of sand-rootcomposite by treating with polyurethane polymer and hence investigating the mechanism of polymer-root-soil interactions. Vegetation roots were selected and mixed with dry sand and polymer solution to prepare remolded specimens. A series ofexperimental tests were then performed at different percentages of root content (0, 0.4, 0.8, 1.2, and 1.6 % by weight of drysand) and polymer content (1, 2, and 4 % by weight of dry sand) to evaluate the shear parameters and unconfinedcompressive strength (UCS). The combined mechanism was studied by scanning electron microscopy (SEM) images. Theresults showed that the strengthening effect has greater efficiency with higher polymer content. Through varying contents ofvegetation root, it was found that low root content induced an undesirable weakening effect on the strength of the treated soil. However, this situation was somewhat improved with the increase in root content. The good flexibility of polymers not onlypromote the capacity of soil to energy absorption, but also impart good ductility to soil. The presence of polymers greatlystrengthens soil stability due to its special network structure, by which the improved shear resistance at the root-soil interfaceprovides sufficient anchorage effect for the tensile strength of roots to be fully mobilized. Overall, the synergistic effect ofroot reinforcement and polymer treatment has the potential for its use in soil stabilization.