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아크릴로니트릴-4비닐피리딘 공중합체의 전기 전도성에 관한 연구
전재완,송해영,김동철,이래연 忠南大學校 産業技術硏究所 1987 산업기술연구논문집 Vol.2 No.2
Conducting Polymer was obtained by the modification of PAN4VP-Cu(Ⅱ) complex with iodine in acetone. The properties such as morphology, IR-spectrum, thermal degradation, catalytic activity, moisture regain, dye adsorption, tensile strength and favorable conditions for preparing the conducting polymer complex were investigated. Electrical conductivity was measured by changing the concentration of cupric salts and reation time. The experimental results are as follows: 1) The pH condition for the formation of PAN4VP complex was in the range from 10 to 11. 2) The morphology of PAN4VP-Cu(Ⅱ) complex and Cu S-PAN4VP was more compact than that of PAN4VP. 3) The catalytic activity of PAN4VP-Cu(Ⅱ) complex in dicomposition of hydrogen peroxide was affected by concentration of CuCl₂and reaction time, and was increased with their rises. 4) Maximum value of electrical condustivity of PAN4VP-Cu(Ⅱ) complex was 5.5×10Ω㎝ When modified with iodine in acetone, and that of CuxS-PAN4VP was 1.2×10Ω㎝ at the 40g/ℓ concentration of cupric sulfate. 5) Moisture regain of Cu S-PAN4VP was decreased by the introducing of Cu S, but dye adsorption was not decreased.
Lee, Ju-Yeon,Jung, Kyung Hee,Morgan, Michael J.,Kang, Yi-Rae,Lee, Hee-Seung,Koo, Gi-Bang,Hong, Soon-Sun,Kwon, Sung Won,Kim, You-Sun American Association for Cancer Research 2013 Molecular cancer therapeutics Vol.12 No.3
<P>The TRAIL pathway is a potential therapeutic target for anticancer drugs due to selective cytotoxicity in cancer cells. Despite considerable promise, TRAIL or TRAIL receptor agonists have been used thus far with limited success in multiple clinical trials, in part due to acquired TRAIL resistance during chemotherapeutic treatment. Hepatocellular carcinoma (HCC) is a common solid tumor and the third leading cause of cancer-related death worldwide. Classical chemotherapy is not effective for HCC treatment and targeted therapy is limited to sorafenib. Isolated from <I>Panax ginseng</I> CA Meyer, 20(S)-ginsenoside Rg<SUB>3</SUB> is a steroidal saponin with high pharmacologic activity that has been shown to sensitize cells to some chemotherapeutic agents. We investigated the sensitizing effect of Rg<SUB>3</SUB> on TRAIL-induced cell death in HCC cells. We show Rg<SUB>3</SUB> is capable of promoting TRAIL-induced apoptosis in a number of HCC cell lines, including HepG2, SK-Hep1, Huh-7, and Hep3B, but not in normal HL-7702 hepatocytes, indicating that Rg<SUB>3</SUB> sensitization to TRAIL may be specific to cancer cells. Mechanistically, we found that Rg<SUB>3</SUB> upregulates DR5 expression at the transcriptional level. DR5 upregulation in this case is mediated by C/EBP homology protein (CHOP), an important endoplasmic reticulum stress responsive protein. Furthermore, Rg<SUB>3</SUB> is well tolerated and enhances the therapeutic efficacy of TRAIL in mouse xenograft models, suggesting that chemosensitization also occurs <I>in vivo</I>. Taken together, our study identifies Rg<SUB>3</SUB> as a novel anticancer therapeutic agent and supports the further development of Rg<SUB>3</SUB> as a chemosensitizer in combined therapy with TRAIL. <I>Mol Cancer Ther; 12(3); 274–85. ©2012 AACR</I>.</P>
Lee, Eung-Pill,Lee, Soo-In,Jeong, Heon-Mo,Han, Young-Sub,Lee, Seung-Yeon,Park, Jae-Hoon,Jang, Rae-Ha,Hong, Youg-Sik,Jung, Young-Ho,Kim, Eui-Joo,Lee, Sang-Hun,You, Young-Han The Ecological Society of Korea 2019 Journal of Ecology and Environment Vol.43 No.4
Background: Standing biomass, litter production, rate of litter decomposition, amount of litter on forest floor, and amount of soil organic carbon distribution were investigated from March 2016 to November 2018 in order to evaluate the ecosystem value through organic carbon distribution in the Pinus densiflora forest at Namsan, Seoul Metropolitan City. Results: The amount of organic carbon in the Pinus densiflora forest was 261.09 ton C ha<sup>-1</sup> during the research period, and fixed organic carbon in plant through net photosynthesis was 3.2 ton C ha<sup>-1</sup> year<sup>-1</sup>. The organic carbon in plant was 62.77 ton C ha<sup>-1</sup> (24.04%), in litter on the forest floor was 3.65 ton C ha<sup>-1</sup> (1.40%), and in soil was 194.67 ton C ha<sup>-1</sup> (74.56%). The value of plant, litter on forest floor, and soil organic carbon distribution were each 6,277,000 won ha<sup>-1</sup>, 365, 000 won ha<sup>-1</sup>, and 19,467,000 won ha<sup>-1</sup>. The value per ton of fixed organic carbon in plant through net photosynthesis was 320,000 won ha<sup>-1</sup> year<sup>-1</sup> and the value of ecosystem services stored in carbon in the Namsan forest ecosystem was about 26.1 million won ha<sup>-1</sup> for 3 years. Conclusions: The results of this study suggest that the pine forests of Namsan rapidly decompose leaves due to the high atmospheric temperature and accumulate a large amount of organic carbon in the soil to provide climate control regulatory service function.
High-strength carbon nanotube/carbon composite fibers via chemical vapor infiltration
Lee, Jaegeun,Kim, Teawon,Jung, Yeonsu,Jung, Kihoon,Park, Junbeom,Lee, Dong-Myeong,Jeong, Hyeon Su,Hwang, Jun Yeon,Park, Chong Rae,Lee, Kun-Hong,Kim, Seung Min The Royal Society of Chemistry 2016 Nanoscale Vol.8 No.45
<P>In this study, we have developed an efficient and scalable method for improving the mechanical properties of carbon nanotube (CNT) fibers. The mechanical properties of as-synthesized CNT fibers are primarily limited by their porous structures and the weak bonding between adjacent CNTs. These result in inefficient load transfer, leading to low tensile strength and modulus. In order to overcome these limitations, we have adopted chemical vapor infiltration (CVI) to efficiently fill the internal voids of the CNT fibers with carbon species which are thermally decomposed from gas phase hydrocarbon. Through the optimization of the processing time, temperature, and gas flow velocity, we have confirmed that carbon species formed by the thermal decomposition of acetylene (C2H2) gas successfully infiltrated into porous CNT fibers and densified them at relatively low temperatures (650-750 degrees C). As a result, after CVI processing of the as-synthesized CNT fibers under optimum conditions, the tensile strength and modulus increased from 0.6 GPa to 1.7 GPa and from 25 GPa to 127 GPa, respectively. The CVI technique, combined with the direct spinning of CNT fibers, can open up a route to the fast and scalable fabrication of high performance CNT/C composite fibers. In addition, the CVI technique is a platform technology that can be easily adapted into other nano-carbon based yarn-like fibers such as graphene fibers.</P>
Lee, Ilmin,Kang, Won Tae,Shin, Yong Seon,Kim, Young Rae,Won, Ui Yeon,Kim, Kunnyun,Duong, Dinh Loc,Lee, Kiyoung,Heo, Jinseong,Lee, Young Hee,Yu, Woo Jong American Chemical Society 2019 ACS NANO Vol.13 No.7
<P>Piezoelectricity of transition metal dichalcogenides (TMDs) under mechanical strain has been theoretically and experimentally studied. Powerful strain sensors using Schottky barrier variation in TMD/metal junctions as a result of the strain-induced lattice distortion and associated ion-charge polarization were demonstrated. However, the nearly fixed work function of metal electrodes limits the variation range of a Schottky barrier. We demonstrate a highly sensitive strain sensor using a variable Schottky barrier in a MoS<SUB>2</SUB>/graphene heterostructure field effect transistor (FET). The low density of states near the Dirac point in graphene allows large modulation of the graphene Fermi level and corresponding Schottky barrier in a MoS<SUB>2</SUB>/graphene junction by strain-induced polarized charges of MoS<SUB>2</SUB>. Our theoretical simulations and temperature-dependent electrical measurements show that the Schottky barrier change is maximized by placing the Fermi level of the graphene at the charge neutral (Dirac) point by applying gate voltage. As a result, the maximum Schottky barrier change (ΔΦ<SUB>SB</SUB>) and corresponding current change ratio under 0.17% strain reach 118 meV and 978, respectively, resulting in an ultrahigh gauge factor of 575 294, which is approximately 500 times higher than that of metal/TMD junction strain sensors (1160) and 140 times higher than the conventional strain sensors (4036). The ultrahigh sensitivity of graphene/MoS<SUB>2</SUB> heterostructure FETs can be developed for next-generation electronic and mechanical-electronic devices.</P> [FIG OMISSION]</BR>
이래민(Rae-Min Lee),구자춘(Ja-Choon Koo),최연선(Yeon-Sun Choi),이상원(Sang Won Lee) 한국철도학회 2010 한국철도학회 학술발표대회논문집 Vol.2010 No.7
This paper discusses the numerical study on the stability of the high-speed EMU by developing its lumped parameter model including the effect of the creepage. The 6, 10 and 14 degrees-of-freedom (DOF) lumper parameter dynamic models are developed and the critical hunting speeds calculated from each model via Matlab software are analyzed and compared . It is demonstrated that the critical hunting speeds decrease while the degrees-of-freedom increase. In addition, the parametric study is conducted to extract major design parameters to influence on the stability of the high-speed EMU.