(La0.7-xCex)Sr0.3MnO3 세라믹스의 구조적, 전기적 특성

인태연,임정은,박병준,이삼행,이명규,박주석,이성갑 한국전기전자재료학회 2023 전기전자재료학회논문지 Vol.36 No.3

La0.7-xCexSr0.3MnO3 specimens were fabricated by a solid state reaction method and structural and electrical properties with variation of Ce4+ contents were measured. All specimens exhibited a polycrystalline rhombohedral crystal structure, and the (110) peaks were shifted to low angle side with increasing the amount of Ce4+ contents. As Ce4+ ions with different ion radii and charges are substituted with La3+ ions, electrical properties are thought to be affected by changes in the double exchange interaction between Mn3+-Mn4+ ions due to distortion of the unit lattice, a decrease in oxygen vacancy concentration, and an increase in lattice defects. Resistivity gradually decrease as the amount of Ce4+ added increased, and negative temperature coefficient of resistance (NTCR) properties were shown in all specimens. In the La0.5Ce0.2Sr0.3MnO3 specimens, electrical resistivity, TCR and B-value were 31.8 Ω-cm, 0.55%/℃ and 605 K, respectively.

Effect of Different Light Sources and Intensities on the Growth of Astaxanthin-producing Microalgae Haematococcus lacustris (Chlorophyceae)

인태연,윤은영,김태훈 한국생물공학회 2023 KSBB Journal Vol.38 No.4

The green microalga Haematococcus lacustris is a source of astaxanthin, a natural pigment additive with commercial value in functional food, cosmetic, and pharmaceutical industries. Although conventional light sources are being increasingly replaced with light-emitting diodes (LEDs), their applications in microalgal biotechnology remain limited. In this study, we investigated the effects of monochromatic light types, light intensities, and different ratios of mixed light on the growth of two H. lacustris strains, UTEX 2505 and UTEX 16. The maximum cell concentrations of UTEX 2505 (944,000 cells mL−1) and UTEX 16 (653,000 cells mL−1) were obtained under blue LED at a light intensity of 100 µmol m−2 s−1. The concentrations of UTEX 2505 and UTEX 16 cells decreased by 43.7% and 53.3%, respectively, under red LED compared with those under blue LED of the same intensity. In monochromatic light experiments, cell concentrations under different light sources decreased in the following order: blue LED > green LED > fluorescent light > red LED. Growth under monochromatic light yielded a higher cell concentration than that under mixed light ratios. Blue LED was the most effective light source for the growth of H. lacustris. The growth of UTEX 2505 and UTEX 16 was the highest under red:blue LED mixing ratios of 2 : 1 and 1 : 1, respectively. In this study, we optimized the light source and intensity for cultivating H. lacustris, providing basic data for further studies on the complex and condition-dependent photosynthetic reactions of H. lacustris, as well as for mass-culture of microalgae for commercial applications.

Inhibition of cytochrome P450 and uridine 50-diphosphoglucuronosyltransferases by MAM-2201 in human liver microsomes

공태연,김주현,권순상,정재철,김희승,인문교,이혜숙 대한약학회 2017 Archives of Pharmacal Research Vol.40 No.6

MAM-2201, a synthetic cannabinoid, is a potentagonist of the cannabinoid receptors and is increasinglyused as an illicit recreational drug. The inhibitory effects ofMAM-2201 on major drug-metabolizing enzymes such ascytochrome P450s (CYPs) and uridine 50-diphospho-glucuronosyltransferases(UGTs) have not yet been investigatedalthough it is widely abused, sometimes incombination with other drugs. We evaluated the inhibitoryeffects of MAM-2201 on eight major human CYPs (CYPs1A2, 2A6, 2B6, 2C8, 2C9, 2C19, 2D6, and 3A4) and sixUGTs (UGTs 1A1, 1A3, 1A4, 1A6, 1A9, and 2B7) ofpooled human liver microsomes; we thus explored potentialMAM-2201-induced drug interactions. MAM-2201potently inhibited CYP2C9-catalyzed diclofenac 40-hydroxylation,CYP3A4-catalyzed midazolam 10-hydroxylation,and UGT1A3-catalyzed chenodeoxycholic acid24-acyl-glucuronidation, with Ki values of 5.6, 5.4 and5.0 lM, respectively. MAM-2201 exhibited mechanismbasedinhibition of CYP2C8-catalyzed amodiaquine N-deethylationwith Ki and kinact values of 1.0 lM and0.0738 min-1, respectively. In human liver microsomes,MAM-2201 (50 lM) negligibly inhibited CYP1A2,CYP2A6, CYP2B6, CYP2C19, CYP2D6, UGT1A1,UGT1A4, UGT1A6, UGT1A9, and UGT2B7. Based onthese in vitro results, we conclude that MAM-2201 has thepotential to trigger in vivo pharmacokinetic drug interactionswhen co-administered with substrates of CYP2C8,CYP2C9, CYP3A4, and UGT1A3.

Rapid analysis of drugs of abuse and their metabolites in human urine using dilute and shoot liquid chromatography–tandem mass spectrometry

공태연,김주현,김진영,인문교,최경호,김희승,이혜숙 대한약학회 2017 Archives of Pharmacal Research Vol.40 No.2

Liquid chromatography-tandem mass spectrometricmethod for analysis of 113 abuse drugs and theirmetabolites in human urine was developed and validated. Asimple sample clean-up procedure using the ‘‘dilute andshoot’’ approach, followed by reversed phase separation,provided a fast and reliable method for routine analysis. Drugs were separated in a Capcell Pak MG-III C18 columnusing a gradient elution of 1 mM ammonium formate with0.1% formic acid in water and acetonitrile. The total timefor analysis was 32 min. The multiple reaction monitoringmode using two transitions (e.g., quantifier and qualifier)was optimized for both identification and determination. The calibration curves for each analyte were linear over theconcentration ranges of 1–100, 5–100, or 10–100 ng/mLusing 400 lL of human urine sample with the coefficient ofdetermination above 0.9921. The coefficient of variationand accuracy for the intra- and inter-assays of the testeddrugs at three QC levels were 1.1–14.6 and 86.7–106.8%,respectively. The present method was successfully appliedto the analysis of forensic urine samples obtained from 17drug abusers. This method is useful for the rapid andaccurate determination of multiple drug abuse with a smallamount of urine in forensic and clinical toxicology.

산화 및 알칼리 후처리의 땅콩 껍질 바이오차를 이용한 철과 크롬 제거에 미치는 영향

서혜린(Hye-Lin Seo),인태연(Tae-Yeon Yin),권오인(Oh-In Kwon),전강민(Kangmin Chon) 대한환경공학회 2020 대한환경공학회지 Vol.42 No.2

목적 : 본 연구의 주요 목적은 단순 열분해를 통해 생산된 땅콩 껍질 바이오차(PB), KMnO₄ 후처리를 한 바이오차(PB-Ox), KMnO₄와 KOH 후처리를 한 바이오차(PB-Ox-A)에 의한 3가 철과 6가 크롬의 제거효율을 비교하는 것이다. 방법 : PB, PB-Ox, PB-Ox-A에 의한 3가 철과 6가 크롬의 제거기작을 알아보기 위하여 반응 동역학 모델과 흡착등온식 모델을 적용하였다. 또한, 다양한 변수들이 3가 철과 6가 크롬 흡착에 미치는 영향을 알아보기 위하여 투입량(0.8 - 2.4 g/L), 온도(15 - 35℃) 및 이온강도(0.05 - 0.2 M NaNO₃) 조건을 변화시키면서 흡착실험을 수행하였다. 결과 및 토의 : PB-Ox-A는 PB와 PB-Ox보다 중금속 흡착에 연관된 표면 작용기(O/C of PB = 0.064; O/C of PB-Ox= 0.058; O/C of PB-Ox-A = 0.188)가 잘 발달되었고, 더 넓은 표면적(PB = 351.5 m²/g; PB-Ox = 344.0 m²/g; PB-Ox-A = 2121.5 m²/g)과 공극(PB = 0.15 cm³/g; PB-Ox = 0.15 cm³/g; PB-Ox-A = 0.96 cm³/g)으로 인해 3가 철과 6가 크롬의 제거율이 높았다. PB, PB-Ox, PB-Ox-A의 투입량이 증가할수록 대상 중금속들에 대한 높은 제거율을 나타냈고, PB-Ox-A가 PB와 PB-Ox보다 높은 제거율을 나타내었다. PB, PB-Ox, PB-Ox-A에 의한 3가 철과 6가 크롬 제거는 유사 1차 속도모델보다 유사 2차 속도모델에 적합한 것으로 보아 화학적 흡착에 대한 특성을 따르는 것으로 나타났으며, PB, PB-Ox, PB-Ox-A를 이용한 3가 철과 6가 크롬의 제거는 모두 Freundlich 등온흡착모델에 적합한 것으로 보아 다층 흡착을 따르는 것으로 판단된다. 온도변화에 따른 PB, PB-Ox, PB-Ox-A에 의한 3가 철과 6가 크롬의 제거율의 변화는 크지 않는 것으로 나타났다. 바이오차에 의한 3가 철의 제거는 이온강도변화에 크게 영향을 받지 않았지만, 6가 크롬의 경우 이온강도가 증가할수록 제거율이 감소하였다. PB, PB-Ox, PB-Ox-A를 비교하였을 때 3과 철과 6가 크롬의 제거에 대해 PB-Ox-A가 가장 좋은 흡착제라는 것을 확인할 수 있었다. 결론 : 본 연구는 KMnO₄(산화)및 KOH(알칼리) 후처리가 표면특성 개선을 통하여 땅콩 껍질 바이오차의 중금속 흡착효율을 향상시킬 수 있다는 것을 입증하였다. 또한, 다양한 조건에서 PB, PB-Ox, PB-Ox-A에 의한 중금속 흡착 메커니즘을 조사한 결과 중금속의 물리화학적 특성과 흡착제의 표면 특징들이 PB, PB-Ox, PB-Ox-A의한 3가 철과 6가 크롬의 흡착에 중요한 역할을 하는 것으로 나타났다. Objectives : The main goal of this study was to compare the removal efficiency of trivalent iron and hexavalent chromium by peanut shell biochars (i.e., PB), post-treated peanut shell biochars using KMnO₄ (i.e., PB-Ox), and secondary post-treated peanut shell biochars using KOH (i.e., PB-Ox-A). Methods : The adsorption mechanisms of trivalent iron and hexavalent chromium by PB, PB-Ox, and PB-Ox-A were investigated using two types of adsorption kinetic and isotherm models. Furthermore, the adsorption experiments were performed under different adsorbent dosages (0.8 - 2.4 g/L), temperatures (15 - 35℃) and ion strengths (0.05 - 0.2 M NaNO₃) to identify their effects on the adsorption of trivalent iron and hexavalent chromium by PB, PB-Ox, and PB-Ox-A. Results and Discussion : Trivalent iron and hexavalent chromium could be more effectively removed by PB-Ox-A than PB and PB-Ox because of its higher contents of oxygen containing functional groups (O/C of PB = 0.064; O/C of PB-Ox = 0.058; O/C of PB-Ox-A = 0.188), higher surface area (PB = 351.5 m²/g; PB-Ox = 344.0 m²/g; PB-Ox-A = 2121.5 m²/g), and greater pore volume (PB = 0.15 cm³/g; PB-Ox = 0.15 cm³/g; PB-Ox-A = 0.96 cm³/g). The removal efficiencies of trivalent iron and hexavalent chromium by PB, PB-Ox and PB-Ox-A were increased with increasing the adsorbent dosages (PB-Ox-A > PB-Ox > PB). The adsorption kinetic experiments demonstrated that the pseudo second order rate model was suitable for the removal of trivalent iron and hexavalent chromium by PB (R² of Fe<SUP>3+</SUP> = 0.99; R² of Cr<SUP>6+</SUP> = 0.99), PB-Ox (R² of Fe<SUP>3+</SUP> = 0.98; R² of Cr<SUP>6+</SUP> = 0.98), PB-Ox-A (R² of Fe<SUP>3+</SUP> = 0.99; R² of Cr<SUP>6+</SUP> = 0.99). Furthermore, the removal of trivalent iron and hexavalent chromium using PB, PB-Ox and PB-Ox-A was well fitted to the Freundlich isotherm absorption model (R² of Fe<SUP>3+</SUP> = 0.997 - 0.999;R² of Cr<SUP>6+</SUP> = 0.995 - 0.998). The changes of temperature did not show significant effects on the removal of trivalent iron and hexavalent chromium by PB, PB-Ox, and PB-Ox-A. The removal efficiency of trivalent iron by PB, PB-Ox and PB-Ox-A was not influenced by the ionic strength whereas the removal efficiency of hexavalent chromium by PB, PB-Ox and PB-Ox-A was considerably decreased with increasing the ionic strength. These observations are evident that PB-Ox-A is the most effective adsorbent for the removal of trivalent iron and hexavalent chromium. Conclusions : The proposed post-treatment procedures might improve the surface properties of peanut shell biochars intimately associated with the removal of trivalent iron and hexavalent chromium. The physicochemical properties of the heavy metals and the biochars were found to be key factors governing the adsorption mechanisms of trivalent iron and hexavalent chromium by PB, PB-Ox and PB-Ox-A.