• Bulletin of the Korean Chemical Society
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• v.34 no.10
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• pp.2995-3004
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• 2013

The structural, electronic, and optical properties of poly(3-hexylthiophene) (P3HT) have been comprehensively studied by density functional theory (DFT) to rationalize the experimentally observed properties. Rather, we employed periodic boundary conditions (PBC) method to simulate the polymer block, and calculated effective charge mass from the band structure calculation for describing charge transport properties. The simulated results of P3HT are consistent with the experimental results in band gaps, absorption spectra, and effective charge mass. Based on the same calculated methods as P3HT, a series of polymers have been designed on the basis of the two types of building blocks, furofurans and furofurans substituted with cyano (CN) groups, to investigate suitable polymers toward polymer solar cell (PSC) materials. The calculated results reveal that the polymers substituted with CN groups have good structural stability, low-lying FMO energy levels, wide absorption spectra, and smaller effective masses, which are due to their good rigidity and conjugation in comparison with P3HT. Besides, the insertion of CN groups improves the performance of PSC. Synthetically, the designed polymers PFF1 and PFF2 are the champion candidates toward PSC relative to P3HT.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.05a
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• pp.84-87
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• 2005

본 논문에서는 p-type 고분자 물질인 P3HT (Poly-3-hexylthiophene)를 잉크젯 프린팅 방식으로 활성화층을 적층함으로써 Organic thin film transistor를 제작하여 이에 대한 특성을 연구하였다. Piezoelectric 방식의 잉크젯 프린팅을 이용하여 P3HT single drop jetting 시 두께 $150{\sim}200{\AA}$, 직경 약 70 ~ 80 um정도의 drop profile을 얻을 수 있었다. P3HT의 solvent로서 Chlorobenzene을 사용하여 농도 약 0.5 wt.%의 Ink-jet용 ink를 제작하여 이를 Channel Width 37, 236 um 크기의 Au 전극 위에 jetting 하여 각각의 특성을 측정하였다. 상기 실험은 상온의 외부환경에서 실시되었으며 실험 결과 최대 ${\mu}=1{\times}10^{-2}\;cm^2/Vsec$, $I_{on}/I_{off}=10^3{\sim}10^4$ 정도로서 off current가 높은 편이나 이동도 측면에서는 다른 방법의 박막 증착 실험결과와 비교할 때 동등 수준의 결과를 얻을 수 있었다.

• Transactions on Electrical and Electronic Materials
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• v.13 no.2
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• pp.98-101
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• 2012

I studied the stability of organic photovoltaic cells in terms of P3HT:PCBM-71 blend ratio as a function of storage time. I obtained the best cell performance by optimizing the blend ratio of electron donor and electron acceptor within the active layer. In this study, I found that the more the P3HT:PCBM ratio increases within the active layer, the more the cell efficiency decreases as the storage time increases. As a result, the best optimized blend ratio was the 1:0.6 ratio of P3HT:PCBM-71, and cell efficiency of the device with the 1:0.6 blend ratio was 4.49%. The device with the best cell efficiency showed good stability.

• Natural Product Sciences
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• v.15 no.1
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• pp.32-36
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• 2009

Glutamate causes neurotoxicity through formation of reactive oxygen species and activation of mitogen-activated protein kinase (MAPK) pathways. MAPK phosphatase-1 (MKP-1) is one of the phosphatases responsible for dephosphorylation/deactivation of three MAPK families: the extracellular signal-regulated kinase-1/2 (ERK-1/2), the c-Jun N-terminal kinase-1/2 (JNK-1/2), and the p38 MAPK. In this report, the potential involvement of MKP-1 in neuroprotective effects of curcumin, the active ingredient of turmeric (Curcuma longa), was examined using HT22 cells. Glutamate caused cell death and activation of ERK-1/2 but not p38 MAPK or JNK-1/2. Blockage of ERK-1/2 by its inhibitor protected HT22 cells against glutamate-induced toxicity. Curcumin attenuated glutamate-induced cell death and ERK-1/2 activation. Interestingly, curcumin induced MKP-1 activation. In HT22 cells transiently transfected with small interfering RNA against MKP-1, curcumin failed to inhibit glutamate-induced ERK-1/2 activation and to protect HT22 cells from glutamate-induced toxicity. These results suggest that curcumin can attenuate glutamate-induced neurotoxicity by activating MKP-1 which acts as the negative regulator of ERK-1/2. This novel pathway may contribute to and explain at least one of the neuroprotective actions of curcumin.

• The Journal of Korean Physical Therapy
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• v.24 no.2
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• pp.134-142
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• 2012

Purpose: This study examined the effect on postural control during the stimulation of haptic touch with fingertip on the stable surface at quiet standing posture, squat flexion stage, 60 degrees squat stage and squat extension stage. Methods: The postural sway was measured on the force platform, while 30 subjects were squatting, under three different haptic touch conditions (No Touch [NT], Light Touch [LT], Heavy Touch [HT]), above the touch pad in front of their body midline. Three different haptic touch conditions were divided into 1) NT condition; squatting as right index fingers held above the touch pad, 2) LT condition (<1N); squatting as the touch pad was in contact with right index fingers pulp with a pressure not exceeding 1N and 3) HT condition; squatting as subjects were allowed to use the touch pad for mechanical support by transmitting onto it with as much force, choosing with their index fingers. Results: There was significant decrease in LT, rather than that of NT (p<0.01), and in HT, rather than that of LT (p<0.01), as the results of the distance and velocity of center of pressure (COP) in mediolateral direction at quiet standing position. In anteroposterior direction, the distance and velocity of COP in LT and HT showed significant decrease, when compared to that of the data of NT (p<0.01). There was no significant difference between the 3 conditions (NT, LT, and HT), with respect to the distance and velocity of COP in mediolateral direction, during dynamic balance (squat flexion stage, squat extension stage) (p>0.05). In anteroposterior direction, the results of the distance and velocity of COP in HT showed significant decrease when compared to that of the data of NT (p<0.05). Conclusion: Light touch, during the task, decreased the postural sway at static balance. The results suggest that haptic touch should be applied, appropriately, because it varies the effects according to different conditions.

• Archives of Pharmacal Research
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• v.27 no.12
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• pp.1253-1257
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• 2004

6-Methoxydihydrosanguinarine (6ME), a benzophenanthridine alkaloid derived from the methanol extracts of Hylomecon hylomeconoides, showed a dose-dependent effect at 1-10 ${\mu}M$ on causing apoptotic cell death in HT29 colon carcinoma cells $(IC_{50} = 5.0{\pm}0.2 {\mu}M)$. Treatment of HT-29 cells with 6ME resulted in the formation of internucleosomal DNA fragmentation. Treatment of the cells with 6ME caused activation of caspase-3, -8 and 9 protease and subsequent proteolytic cleavage of poly(ADP-ribose)polymerase. 6ME increased the expression of p53 and Bax and decreased the expression of Bid. These results indicate that p53 and proapoptotic Bcl-2 family proteins might participate in the antiproliferative activity of 6ME in HT29 cells.

• Korean Journal of Veterinary Research
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• v.34 no.3
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• pp.447-456
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• 1994

In order to elucidate the characterization of receptors involved in inestinal motility of Israeli carp, spontaneously contracting Israeli carp intestinal preperations were prepared and mounted in the organ chambers for contraction traicings using a polygraph. Various contractile agonists were treated and their dose-response curves were constructed. $EC_{50}$ values$(pD_2)$ of each agonist on specific receptors, $pA_2$ values of competitive antagonists against some agonists, and $K_1$, values of noncompetitive antagonists against some agonists were analyzed for characterization of receptors related with the intestinal contraction. Results obtained through the experiments were summarized as follows: 1. Acetylcholine(ACh) exhibited biphasic dose-response curves: initial ACh-induced dose dependent contractions were observed in pM levels but followed by decreased response in in-between concentration levels. Dose dependent contractions reappeared in ${\mu}M$ level. The peaks in pM and ${\mu}M$ levels appeared in $10^{-13}M$ and $3{\times}10^{-5}M$, respectvely. 2. Carbachol(CaCh) exhibited dose dependent contractions from $10^{-9}M$ to $10^{-5}M$, and its $pD_2$ values were higher than those of ACh($5.60{\pm}0.11$). ACh and CaCh exhibited equiactive contractions. Nicotine had no effects on contractile responses of Israeli carp intestine. 3. ACh-induced responses were inhibited by atropine($K_1:7{\times}10^{-8}M$), a muscarinic antagonist, in a non-competitive manner. But CaCh-induced responses were inhibited by both antimuscarinic atropine($pA_2:9.52{\pm}0.14$) and selective $M_2$ antagonistic 4-DAMP($pA_2:8.16{\pm}0.09$), in competitive manners. Nicotine receptor antagonistic decamethonium and hexamethonium had no effects on ACh-and CaCh-induced contractions. Therefore, the cholinergic receptor related to intestinal motility of Israeli carp was assumed as $M_2$ type. 4. In Israeli carp intestine, 5-HT (serotonin) exhibited dose dependent contractions in concentration range from $10^{-8}M$ to $10^{-5}M$. The maximal responses, however, were corresponded to about 50% of those of ACh or CaCh. 5-HT induced contractions were inhibited by $5-HT_2$ antagonistic ketanserin ($K_1: 7.8{\times}10^{-4}M$) in a non-competitive manner, but not by both of anti $5-HT_1$, spiperone and anti $5-HT_3$, MDL-72222. Hence, $5-HT_2$ receptors are suggested to be existed in Isreli carp intestine.

• Journal of the Korean Society of Food Science and Nutrition
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• v.43 no.12
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• pp.1827-1834
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• 2014

Colon cancer is the third highest cause of death in Korea. Known dietary causes of colon cancer include a diet rich in fat and red meat as well as inadequate intake of dietary fiber, fruits, and vegetables. Therefore, recent research has focused on the anticancer effects of natural products. Opuntia humifusa is a type of prickly pear that is known to contain biologically active compounds that can be used in the treatment of diabetes mellitus, arteriosclerosis, and hyperglycemia. The aim of this study was to determine whether or not O. humifusa extract affects proliferation, cell death, and DNA fragmentation in human carcinoma HT-29 cells. O. humifusa is rich in carbohydrates, minerals (Mg, K, and Ca), and total phenolics. HT-29 cells were treated with extracts of O. humifusa at concentrations of 0, 0.25, 0.5, 1, and 2 mg/mL for 24 or 48 hours. O. humifusa extracts inhibited HT-29 cell growth in a dose-dependent manner. Hoechst 33342/PI double staining and Comet assay were performed to observe changes in nuclei of cancer cells undergoing cell death. The results of both tests showed that O. humifusa extract induced cell shrinkage, DNA fragmentation, and chromatin condensation dose-dependently in HT-29 cells. The results of this study suggest that O. humifusa extract inhibits the growth of HT-29 via induction of DNA fragmentation and chromatin condensation.

• Toxicological Research
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• v.12 no.2
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• pp.171-179
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• 1996

To investigate the involvement of $5-HT_{2A}/ 5-HT_{2C} receptors in the developmental toxicity of cocaine in rats, mianserin (2.5 mg/kg), a $5-HT_{2A}/5-HT_{2C}$ receptor antagonist, and/or cocaine HCl (45 mg/kg) were administered intraperitoneally (i.p.), during postnatal days (PND) 7-13. Behavioral assessments for the rat pups were done after 100 days of age by using the progressive ratio schedule of reinforcement (FR 1-FR 128, doubled everyday) and cocaine challenge (5, 15 or 30 mg/kg i.p.) upon established FR 32 behavior. Cocaine injected just prior to the FR 32 session suppressed the established FR 32 responding in a dose-dependent manner. The low dose of cocaine did not affect the FR 32 responding, while the high dose of cocaine suppressed it in all experimental groups. However, by the middle dose of cocaine, rats previously received water-cocaine in their early life showed a marked resistance to cocaine-induced behavioral suppression, and this resistance was not observed in rats received both mianserin and cocaine in their early life. These results suggest that $5-HT_{2A}/ 5-HT_{2C}$ receptors may have an important role for the persistently altered behavioral sensitivity to cocaine caused by exposure to cocaine during development.

• Korean Chemical Engineering Research
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• v.49 no.1
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• pp.95-100
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• 2011

During the development of low band-gap organic materials(p-type semiconducting organic compounds) for organic solar cells, an oligomer consisting of 2,5-dioctyloxyphenylene(OP), 3-hexylthiophene(HT), and 2,3-dimethylthieno[ 3,4-b]pyrazine(TP) as repeat units, oligo(OP-HT-TP), was synthesized. The oligomer was amorphous in nature in the temperature range studied, and well soluble in common organic solvents such as chloroform. The maximum absorption wavelength was 716 nm in solid state. The band-gap and HOMO/LUMO energy levels of oligo(OP-HT-TP) were measured to be 1.20 eV and -5.27/4.04 eV, respectively. However, the absorbance of the oligomer at maximum absorption wavelength was less than one fifth of that of poly(3-hexylthiophene) which has been most frequently used in fabrication of organic solar cells.