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Effect of hemin and zinc on experimental colon carcinogenesis in mice
최효석,김준호,남상윤,윤영원,정재황,이범준 한국예방수의학회 2019 예방수의학회지 Vol.43 No.1
Excessive intake of red meat has been associated with colon carcinogenesis. The effect of hemin and zinc on colon carcinogenesis was investigated in male ICR mice. After acclimation for 1 week, five-week-old mice received three s.c. injections (0-2nd weeks of the experiment) of azoxymethane (AOM; 10 mg/kg b.w.) weekly and were treated by 2% dextran sodium sulfate (DSS) in drinking water for the next 1 week to induce aberrant crypt foci (ACF). Mice were fed on AIN-76A purified rodent diet for 6 weeks. There were three experimental groups; control, hemin, and hemin + zinc groups. The daily oral doses of hemin and zinc were 534 mg/kg and 55 mg/kg b.w., respectively. After staining colonic mucosa with 0.2% methylene blue, the ACF, aberrant crypts (AC), and polyps were counted. Lipid peroxidation in liver was evaluated by thiobarbituric acid-reactive substances (TBARS) assay. The numbers of AC, ACF, large ACF (i.e., ≥4 AC/ACF), and polyps in the hemin group were higher than those in the control group. In hemin + zinc group, the numbers of AC, ACF, large ACF were significantly lower compared to the hemin or control groups (p < 0.05), and the number of polyps was also significantly lower compared to that in the hemin group (p < 0.05). The TBARS level in the livers of the hemin + zinc group was significantly lower than that of the hemin group (p < 0.05). These results suggest that hemin enhances colon carcinogenesis and that co-treatment with zinc can protect against the induction of colon carcinogenesis.
최효석,이중명 한국펄프·종이공학회 2018 펄프.종이技術 Vol.50 No.6
Pine organosolv residues containing 13.0% residual lignin was prepared by the LAS (low temperature, atmospheric pressure, and short reaction time) pulping method. In order to produce a series of LAS micronized-residues with different residual lignin contents from 3.0% to 9.0%, the LAS micronized-residues was treated by sodium chlorite. Each LAS micronized-residues was subjected to dissolution treatments in a urea/NaOH/water solution to investigate the effect of lignin content. With the decrease of residual lignin content of the LAS micronized-residues from 13.0% to 3.0%, the dissolution yield of residues was increased by only 2.5%, suggesting that the removal of residual lignin in the residues did not significantly affect the dissolution yield. This result indicated that the combination effects of DP (degree of polymerization), hemicellulose and lignin contents in the residues on dissolutions were involved in a complex way.
반구형 나노구조의 Si(111) 기판 위에 성장된 GaN 나노막대 특성평가
최효석,이상태,김문덕,김송강,우용득 한국물리학회 2012 새물리 Vol.62 No.12
In this study, we investigated the structural and the optical properties of GaN nanorods grown on Si(111) substrates with a dome nanostructure by using plasma-assisted molecular beam epitaxy. We found that the GaN nanorods grown on Si(111) substrates with a dome nanostructure showed (0002) diffraction, indicating a c-axis direction, but the number density of GaN nanorods was lower and the width of the GaN nanorods was wider than they were without the dome nanostructure. Also, by using photoluminescence measurements, we found a strong emission peak at 3.42 eV that was related to stacking faults in the GaN nanorods grown on a substrate with dome nanostructure substrate. The activation energy of the 3.42 eV peak was smaller than and the activation energy of the D^oX peak was two times larger than those of the nanorod deposited on a substrate with a dome nanostructure. These behaviors can be explained by defects in the nanorods being related to stacking faults that have a role as nonradiative recombination centers at elevated measurement temperatures, so that excitons are strongly bound to those defects. The properties of the peaks will provide fruitful information for understanding the origin of stacking fault defects. 본 연구에 사용된 GaN 나노막대는 반구형 덮게 구조를 갖는 Si(111)기판위에 plasma-assisted molecular beam epitaxy 법으로 성장되었다. 반구형 위에 성장된 GaN 나노막대는 c축 성장을 나타내는 GaN(0002)회절신호를 확인하였으며, 평탄면에 성장된 나노선보다 나노막대의밀도는 낮았지만 폭은 오히려 큼을 확인 하였다. PL 관측에서 반구형덮게 모양의 기판위에 성장된 나노막대의 경우 3.42 eV에서 적층결함과관계된 강한 발광을 보였으며 이 신호의 활성화 에너지는 평탄면기판위에 성장된 나노선의 활성화 에너지보다 작았으며, D^oX 의활성화 에너지 또한 약 2배 큰 값을 보였다. 이는 나노막대 내 적층결함관련된 결함들이 온도가 높아지면서 비발광재결합센터 작용하고 이들에엑시톤들이 강하게 구속되기 때문으로 나타나는 현상으로 여겨진다. 나노막대에서 이들 신호에 대한 이해는 적층결함관련 중요한 정보를제공할 것으로 보인다.