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Effects of Hf Incorporation on Indium Zinc Oxide Thin-Film Transistors using Solution Process
Xifeng Li,Enlong Xin,Jianhua Zhang 대한금속·재료학회 2015 ELECTRONIC MATERIALS LETTERS Vol.11 No.1
Thin-film transistors (TFTs) were fabricated by employing amorphoushafnium indium zinc oxide (HIZO) thin films as the active channellayer by the solution process. Thermogravimetry-differential thermalanalysis, transmittance measurements, atomic force microscopy,scanning electron microscopy, x-ray diffraction, and Fourier transforminfrared analysis were used to study the formation, structure, andoptical properties of the HIZO films. The results showed that theaddition of Hf to the IZO system resulted in suppression of carriergeneration. The HIZO TFTs exhibited lower off-currents and higher onoffcurrent ratios than IZO TFTs without Hf doping. HIZO TFTs with aHf doping content of 5 at. % obtained a threshold voltage of 3.7 V, amobility of 0.27 cm2 V−1 s−1, a subthreshold swing of 1.2 V/dec, and anon-off current ratio of 106.
${\gamma}-Pyrone$ Derivatives, Kojic Acid Methyl Ethers from a Marine-Derived Fungus Altenaria sp.
Li, Xifeng,Jeong, Jee-Hean,Lee, Kang-Tae,Rho, Jung-Rae,Choi, Hong-Dae,Kang, Jung-Sook,Son, Byeng-Wha The Pharmaceutical Society of Korea 2003 Archives of Pharmacal Research Vol.26 No.7
Kojic acid dimethyl ether (1), and the known kojic acid mono methyl ether (2), kojic acid (3) and phomaligol A (4) have been isolated from the organic extract of the broth of the marine-derived fungus Altenaria sp. collected from the surface of the marine green alga Ulva pertusa. The structures were assigned on the basis of comprehensive spectroscopic analyses. Each isolate was tested for its tyrosinase inhibitory activity. Kojic acid (3) was found to have significant tyrosinase inhibitory activity, but compounds 1, 2, and 4 were found to be inactive.
Li, Xifeng,Kim, Min Kyung,Lee, Uk,Kim, Se-Kwon,Kang, Jung Sook,Choi, Hong Dae,Son, Byeng Wha The Pharmaceutical Society of Japan 2005 Chemical & pharmaceutical bulletin Vol.53 No.4
<P>New 3-amino-5-ethenylcyclopentenones, myrothenones A (4) and B (5), were isolated together with known 6-<I>n</I>-pentyl-α-pyrone (1), trichodenone A (2), and cyclonerodiol (3) from the marine algicolous fungus of genus of <I>Myrothecium</I>. The structure and absolute stereochemistry of the new compounds were established by spectral interpretation and X-ray analysis. Compounds 1 and 4 exhibited a tyrosinase inhibitory activity with IC<SUB>50</SUB> value of 0.8 and 6.6 μ<SMALL>M</SMALL>, respectively, which are more active than kojic acid (IC<SUB>50</SUB>, 7.7 μ<SMALL>M</SMALL>) currently being used as a functional personal-care compound.</P>
Yong Li,Xifeng Li,Byeng Wha Son 한국생약학회 2005 Natural Product Sciences Vol.11 No.3
Bioassay-guided fractionation of an organic extract of the broth from the marine-derived fungus of thegenus Aspergillus led to the isolation of the polyketides, (+)-epoxydon (1), (+)-epoxydon monoacetate (2),gentisyl alcohol (3), 3-chlorogentisyl alcohol (4), and methylhydroquinone (5). Compounds 1-5 showed a potentantibacterial activity against the methicillin-resistant and multidrug-resistant Staphylococcus aureus (MRSA andMDRSA) with MIC (minimum inhibitory concentration) values of 12.5, 12.5, 12.5, 50.0, and 6.2g/mL,respectively. Compounds 1-4 also exhibited a significant radical scavenging activity against 1,1-diphenyl-2-picrylhydrazyl (DPPH) with IC50 values of 6.0, 15.0, 7.0, and 1.0 µM, respectively.
MODELING AND CONTROL OF A HIGH SPEED ON/OFF VALVE ACTUATOR
Jigen Fang,Xifeng Wang,Jinjun Wu,Shuai Yang,Liang Li,Xiang Gao,Yue Tian 한국자동차공학회 2019 International journal of automotive technology Vol.20 No.6
Accurate electromagnetic force control in a high speed on/off valve actuator (HSVA) can improve the performance of a vehicle braking system, and an accurate theoretical model is the key to smoothly controlling the high speed on/off valve. Therefore, a nonlinear model of an HSVA is proposed in this paper. Three subsystems are modeled as a spring/ mass/damper system, a nonlinear resistor/inductor system and a multiwall heat transfer system, respectively. Then, a slidingmodel controller combined with a sliding-model observer is designed to adjust the electromagnetic force for an accurate HSVA state control, taking the effect of the coil heating into account. The feasibility of the three submodels and the slidingmodel controller are verified by comparing the simulation results with the experimental results obtained on a test bench. Our study shows that the three subsystems are coupled to one another through resistance, displacement, and temperature. When the excitation voltage exceeds 9 V, the coil temperature can reach more than 150 degrees Celsius within 300 s, and the electromagnetic force decreases by approximately 30 %. However, by applying the above control strategy, the electromagnetic force can also be stable, fluctuating within 5 % even if the temperature of the coil rises to the thermal equilibrium temperature.
Application of Marine Biomaterials for Nutraceuticals and Functional Foods
Chen Zhang,Xifeng Li,김세권 한국식품과학회 2012 Food Science and Biotechnology Vol.21 No.3
Recently, a great deal of interest has been paid by the consumers towards natural bioactive compounds as functional ingredients in the diets due to their various health beneficial effects. Hence, it can be suggested that bio-processed marine products are alternative sources for synthetic ingredients that can contribute to consumer’s well-being, as a part of nutraceuticals and functional foods. The ultra filtration membrane bioreactor is a novel technology to bio-process marine products. This review presents an overview of bio-processing and perspectives of bioprocessed marine products for use as nutraceuticals and functional foods.