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분자선 에피탁시로 Si 기판 위에 성장한 GaAs/Ge 에피층의 특성
우용득,이해익 우석대학교 부설 기초과학연구소 1997 기초과학연구소 논문집 Vol.2 No.-
Properties of GaAs/Ge epilayers grown using two step growth method on Si substrates by molecular beam epitaxy(MBE) are investigated using scanning electron microscopy(SEM), transmission electron microscopy(TEM), double crystal X-ray diffraction(DCXD), photolumin escence(PL) spectroscopy and Raman spectroscopy. PL. Raman and DCXD results show that the GaAs epilayer grown by two step growth method has best crystallinites. Because of the high temperature growth in two step growth method has an annealing effect upon the inital prelayer and the Ge buffer layer, resulting in the suppressed dislocatin initation.
Deuk-Yeong Lee,Geun-Hyoung Choi,Jin-Ho Rho,Hyo-Sup Lee,Sang-Won Park,Kyeong-Yeol Oh,김진효 한국응용생명화학회 2020 Journal of Applied Biological Chemistry (J. Appl. Vol.63 No.3
The long-chained perfluoroalkyl acids (PFAAs), perfluorooctanoic acid (PFOA) and perfluorooctanesulfonic acid (PFOS), are a potential exposure risk in the environment, specifically for humans due to high levels of bioaccumulation, persistence, and toxicity. In the current study, the plant uptake factors (PUFs) of spinach and Welsh onion were investigated on the three different concentration levels of PFOA and PFOS in soil. Spinach and Welsh onion were divided into three residue groups, a control group and two levels of PFOA and PFOS. The PFAAs spiked soils were aged for six months and the extractable residue of PFOS in the aged soil was reduced to 30-59% of the initial spiked concentrations for PFOS, while PFOA showed almost the same initial spiked concentrations. The PUFs for PFOA and PFOS were 0.111-2.821 and 0.047-3.175 for spinach, and 0.203-0.738 and 0.035-0.181 for Welsh onion, respectively. The highest PUF values in both vegetable were displayed when the residual concentration of PFAAs were part-per-billion (ppb) or sub-ppb in soil.
Deuk-Yeong Lee,Kyeong-Yeol Oh,Yeong-Hun Song,Jin-Hyo Kim 한국농약과학회 2021 한국농약과학회 학술발표대회 논문집 Vol.2021 No.11
Perfluoroalkyl acids (PFAAs) such as perfluorooctanoic acid (PFOA) and perfluorooctanoic acid (PFOS) are emerging persistent organic pollutants (POPs), and used globally as consumer and industrial products. PFOA and PFOS are accumulated to crops from soil and irrigation water, and this is the entering point to human food chain. Thus, the crop contamination of PFAAs should be supervised and assessed the exposure risk. In this study, firstly, the residue of PFAAs was investigated in the agricultural environment and in the locally cultivated crops in the downstream of Nakdong River. Secondly, the dietary exposure risk and the cancer risk of PFAAs were assessed in the food crops. The average concentration of PFOA and PFOS in the downstream of Nakdong River were detected 0.042μg L<SUP>-1</SUP> and 0.027μg L<SUP>-1</SUP> in the irrigation water, and 0.377μg kg<SUP>-1</SUP> and 0.763μg kg<SUP>-1</SUP> in the soil, respectively. The residue concentration of PFOA and PFOS in locally cultivated crops were ranged from <0.001 to 0.746μg kg<SUP>-1</SUP> and <0.001 to 0.115μg kg<SUP>-1</SUP>, respectively. The hazard quotient (HQ) of PFOA and PFOS the locally cultivated 12 crops were 0.668 and 0.080, respectively. The exceed cancer risk of PFOA from the food crops was estimated to 7.6×10-6. Therefore, the futher study for reducing dietary exposure risk of PFAA should be needed.