Fabrication of Photopolymer Hierarchical Micronanostructures by Coupling Electrospinning and Photolithography for SERS Substrates

Wen-Yi Zhang,Xin-Ze Xiao,Chao Lv,Jia Zhao,Gong Wang,Xuan Gu,Ran Zhang,Bin-Bin Xu,Dan-Dan Zhang,Ai-Wu Li,Yong-Lai Zhang,Hong-Bo Sun 한국고분자학회 2013 Macromolecular Research Vol.21 No.3

Reported here is the fabrication of photopolymer hierarchical micronanostructures through a combinative process of electrospinning and subsequent photolithography. Electrospun SU-8 (epoxy-based negative photoresist)nanofiber films have been patterned into gratings with periods of 100, 200, 300, and 400 μm, respectively. Deposition of a silver nanolayer on these interlaced nanofiber films would lead to the formation of various plasmonic nanostructures,and therefore, giving rise to abundant surface-enhanced Raman scattering (SERS) “hot spots”. In the detection of Rhodamine 6G (R6G), probing molecule, the resultant SERS substrates show both high sensitivity and good reproducibility. The SERS enhancement factor could reach as high as ~108, indicating high efficiency. The fabrication of patterned, highly efficient SERS substrates may hold a great promise for the integration of SERS substrates in various microdevices such as microfluidic chips.

Magnesium isoglycyrrhizinate inhibits L-type Ca2+ channels, Ca2+ transients, and contractility but not hERG K+ channels

Yue Lin,Yuanyuan Zhang,Qiongtao Song,Tao Song,Xue Han,Ying Zhang,Xuan Zhang,Xi Chu,Fenghua Zhang,Li Chu,Jianping Zhang 대한약학회 2017 Archives of Pharmacal Research Vol.40 No.10

To explore the cardiovascular protective effectsof Magnesium isoglycyrrhizinate (MI), especially theunderlying cellular mechanisms related to L-type calciumchannels and myocardial contractility, and to examine theeffects of MI on hERG K? current expressed in HEK293cells. We used the whole-cell patch clamp technique,video-based edge detection and dual excitation fluorescencephotomultiplier systems to explore the effect of MIon L-type Ca2? currents (ICa-L) and cell contraction in ratcardiomyocytes. We also examined the rapidly activatingdelayed rectifier potassium current (IKr) expressed inHEK293 cells using a perforated patch clamp. MI inhibitedICa-L in a dose-dependent manner, with a half-maximalinhibitory concentration (IC50) of 0.22 mg/ml, and themaximal inhibitory effect was 61.10 ± 0.59%. MI at aconcentration of 0.3 mg/ml reduced cell shortening by24.12 ± 3.97% and the peak value of the Ca2? transient by36.54 ± 4.96%. MI had no significant influence on hERGK? channels expressed in HEK293 cells at all testpotentials. MI exerts protective effects on the heart via theinhibition of ICa-L and cell shortening in rat cardiomyocytes. However, MI had no significant influence on IKr;thus, MI may exert cardioprotective effects without causingdrug-induced long QT syndrome.

Physiological Races of Phytophthora infestans in Korea

Zhang, Xuan-Zhe,Kim, Byung-Sup The Korean Society of Plant Pathology 2007 Plant Pathology Journal Vol.23 No.3

A total of the 261 Phytophthora infestans isolates collected from 2003 to 2005 in Korea were investigated for their physiological race composition. Among the isolates, we detected 18 physiological races and the dominant races were R0.1.3.5.6.10.11 and R0.1.3.5.6.7.10.11 with frequencies of 18.4% and 11.4%, respectively. All of the P. infestans races carried multiple virulence genes and showed virulence to the potato resistance genes R1, R3, R5, R6, R7, R10 and R11, but not to R8 and R9. Therefore, it is likely that the physiological races of P. infestans were diverse in Korea.

Changes in the Sensitivity to Metalaxyl, Dimethomorph and Ethaboxam of Phytophthora infestans in Korea

Zhang, Xuan-Zhe,Ryu, Kyoung-Yul,Kim, Jeom-Soon,Cheon, Jung-Uk,Kim, Byung-Sup The Korean Society of Plant Pathology 2005 Plant Pathology Journal Vol.21 No.1

Changes of control efficacy of chemical to potato late blight caused by Phytophthora infestans in potato fields from 2001 to 2004 were examined. Control efficacy of metalaxyl was suddenly decreased from 100% in 2002 to 50% in 2004 and that of dimethomorph also was similar to those of metalaxyl. However, the control efficacy of ethaboxam no great change. Both A1 and A2 mating type isolates were isolated from 2001 to 2004 in several areas in Korea. The majority of the P. infestans isolates were A1 mating type. Total 939 isolates of P. infestans obtained from several areas in Korea from 2001 to 2004 were examined for changes of sensitivity to metalaxyl. Frequencies of metalaxyl resistance isolates were gradually increased from 17% in 2001 to 84.2% in 2004, but isolation frequencies of metalaxyl sensitive and intermediate resistant isolate were decreased. Cause of decreasing control efficacy of metalaxyl was thought by increase of resistance isolates in A1 mating type population according to increasing metalaxyl use. Most isolates were grown at 0.5 ${\mu}g/ml of dimethomorph and isolates grown at 1 ${\mu}g/ml of dimethomorph were approximately 10.2-22.9%. However, no isolate was able to grow at 5.0 ${\mu}g/ml. Based on these results, minimum inhibitory concentrations (MIC) of dimethomorph to P. infestans were determined to be 0.5-1.0 ${\mu}g/ml. Our results indicated that the reason decreasing control efficacy of dimethomorph was not caused by occurrence of resistant isolates. About 5% and 12.1% isolates among the total isolates collected in 2003 and 2004 were grown on V-8 juice rye agar containing 1.0 ${\mu}g/ml ethaboxam. The 2.1 and 25.4% isolates had MICs of 0.2-0.4 ${\mu}g/ml, and MIC values of 87.9% and 74.3% isolates were less than 0.2 ${\mu}g/ml concentrations of ethaboxam. Therefore, resistance development by P. infestans to ethaboxam is not likely to occur in the natural condition.

Uniform-fiber-Bragg-grating-based Fabry-Perot Cavity for Passive-optical-network Fault Monitoring

Xuan Zhang,Ning Ning,Tianfeng Yang 한국광학회 2023 Current Optics and Photonics Vol.7 No.1

Study on the Influence of Distribution Lines to Parallel Inverter Systems Adopting the Droop Control Method

Zhang, Xuan,Liu, Jinjun,You, Zhiyuan,Liu, Ting The Korean Institute of Power Electronics 2013 JOURNAL OF POWER ELECTRONICS Vol.13 No.4

This paper takes into account the influence of the different impedances of distribution lines on power distribution among inverters when the inverters are paralleled with the droop control method. The impact of distribution lines on the power distribution of inverters can be divided into two aspects. Firstly, since the distributed generators are in low voltage grids, there is resistive impedance in the distribution lines, which will cause control coupling and reduce system stability. The virtual negative resistive impedance of inverters is adopted in this paper to neutralize the resistive element of distribution lines and thus make the distribution line impedance purely inductive. Secondly, after solving the resistive impedance problem, the difference in the inductive impedance value of distribution lines due to the low density of distributed generators will cause an unequal share of reactive power. With regards to this problem, modification is put forward for the droop control strategy to share the reactive power equally. The feasibility of the design is validated by simulation and experimental results.

Formation of Magnetic Graphene Nanosheets for Rapid Enrichment and Separation of Methyl Orange from Water

Zhang, Feng-Jun,Zhang, Zhuo,Xie, Fa-Zhi,Xuan, Han,Xia, Hong-Chen,Zhu, Lei,Oh, Won-Chun The Korean Ceramic Society 2014 한국세라믹학회지 Vol.51 No.6

Magnetic-graphene nanosheets have been synthesized via a simple effective chemical precipitation method followed by heat treatment. The composite nanosheets are super paramagnetic at room temperature and can be separated by an external magnetic field. The prepared magnetic-graphene nanosheets were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), Raman spectroscopy, and BET surface area analysis. The results demonstrated the successful attachment of iron oxide nanoparticles to graphene nanosheets. It was found that the attached nanoparticles were mainly $Fe_3O_4$. The magnetic-graphene nanosheets showed near complete methyl orange removal within 10 mintues and would be practically usable for methyl orange separation from water.

Electro-optic Coefficient Measurement of the Double Electro-Optic Molecules Polymer based on Terahertz Application

Zhang Ying,Qiu Chengjun,Li You,Zhang Wenlong,Wang Xuan 보안공학연구지원센터 2014 International Journal of Control and Automation Vol.7 No.10

In the terahertz (THz) science research field, electro-optic (EO) polymer possesses many superior characters compared with mineral crystal. Two kinds of the side group EO polymer, polyphosphazene with plmaol grained by 2, 4-dinitroaniline and polyphenylacrylate containing p-nitro bisazo group, are synthesized and characterized. For higher EO coefficient, the double EO molecules polymer thin films are prepared by mixing a small nonlinear optical (NLO) molecule into the side group EO polymer. The principles of preparation are given and the EO coefficients are tested. The effect on the EO coefficients by different mixing proportion and different poling temperature are analyzed in details. Experiments results show that the double EO molecules polymer has fine stability, higher EO coefficient and can be easily processed. This kind of material has the potential to be widely applied in the emission and detection of THz radiation.

Small gas adsorption on Co–N4 porphyrin-like CNT for sensor exploitation: a first-principles study

Zhang Xuanning,Wang Yongjie,Wang Zhenhua,Ma Shouxiao 한국탄소학회 2020 Carbon Letters Vol.30 No.2

Using frst-principles theory, we investigated the adsorption performance of CoN4-CNT towards six small gases including NO, O2, H2, H2S, NH3, and CH4, for exploiting its potential application for chemical gas sensors. The frontier molecular orbital theory was conducted to help understand the conductivity change of the proposed material at the presence of gas molecules. The desorption behavior of gas molecules from CoN4-CNT surface at ambient temperature was analyzed as well to determine its suitability for sensing application. Results show that CoN4-CNT is a promising material for O2 and NH3 sensing due to their desirable adsorption and desorption behaviors while not appropriate for sensing NO due to the poor desorption ability and for sensing CH4 and H2 given the poor adsorption behavior. Our calculation would provide a frst insight into the CoN4-embedded efect on the structural and electronic properties of single-walled CNT, and shed light on the application of CoN4-CNT towards sensing of small gases.

Construct optimized overlay multicast via preferential random walk

Xuan Zhang,Xing Li,Chongrong Li 보안공학연구지원센터 2008 International Journal of Multimedia and Ubiquitous Vol.3 No.2

Tree depth and load balancing are two main metrics in overlay multicast network. Optimizing the two metrics with lightweight overhead is important for live media streaming. This paper proposes one scheme to construct optimized overlay multicast with short tree depth and load balancing via short random walk. The key idea is the preferential random walk based on fitness function in which the tree depth and load balancing metrics are defined as parameters with weighted coefficients. Simulations and experiments show that the fitness function is valid and optimized overlay network could be constructed via preferential random walk. We also find the local and global optimized results occur at some middle value of coefficient between 0 and 1, which is not consist with our intuitions that optimized result with single metric should occur at the boundary of coefficient(0 or 1.0).