• 한국방사선학회논문지
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• 제10권3호
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• pp.153-159
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• 2016

방사선과 상호작용으로 단일 금 나노입자로부터 나타나는 2차 전자의 발생과 입자 크기, 입사 에너지 간의 관계를 확인하였으며, 금 나노입자를 이용한 선량 증가 효과에 대한 기초 자료를 제공하고자 하였다. MCNPX MC code를 이용하여 Monte Carlo 시뮬레이션 기법을 적용하였으며, X선 에너지는 50, 100, 150 kV와 6, 15 MV를 사용하였다. 물 팬텀 내부에 30, 50, 70, 90, 110 nm 직경의 단일 금 나노입자를 위치시켜 10 nm 간격으로 계수 체적을 지정하였다. 금 나노입자로부터 발생하는 전자의 차이는 입자가 없을 때를 기준으로 표준화하여 나타내었으며, X선의 에너지가 낮을수록, 금 입자의 직경이 클수록 많은 전자의 발생을 보였다. 에너지가 낮을수록 나노입자의 크기와 전자 발생 간 선형식에서 높은 기울기 값을 나타내었으며, MV X선에 비해 kV X선에서 현저히 많은 전자의 발생을 보였다. 금 나노입자를 이용한 선량 증가 현상을 이해하기 위한 자료로 활용할 수 있을 것으로 생각되며, 추후 금 나노입자를 포함한 다양한 선량 증가 물질에 대한 추가 연구가 필요할 것으로 사료된다.

• 한국지진공학회논문집
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• 제26권5호
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• pp.191-202
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• 2022

Markov envelope as a theoretical solution of the parabolic wave equation with Markov approximation for the von Kármán type random medium is studied and approximated with the convolution of two probability density functions (pdf) of normal and gamma distributions considering the previous studies on the applications of Radiative Transfer Theory (RTT) and the analysis results of earthquake records. Through the approximation with gamma pdf, the constant shape parameter of 2 was determined regardless of the source distance r_o. This finding means that the scattering process has the property of an inhomogeneous single-scattering Poisson process, unlike the previous studies, which resulted in a homogeneous multiple-scattering Poisson process. Approximated Markov envelope can be treated as the normalized mean square (MS) envelope for ground acceleration because of the flat source Fourier spectrum. Based on such characteristics, the path duration is estimated from the approximated MS envelope and compared to the empirical formula derived by Boore and Thompson. The results clearly show that the path duration increases proportionately to r_o^1/2-r_o², and the peak value of the RMS envelope is attenuated by exp (-0.0033r_o), excluding the geometrical attenuation. The attenuation slope for r_o≤100 km is quite similar to that of effective attenuation for shallow crustal earthquakes, and it may be difficult to distinguish the contribution of intrinsic attenuation from effective attenuation. Slowly varying dispersive delay, also called the medium effect, represented by regular pdf, governs the path duration for the source distance shorter than 100 km. Moreover, the diffraction term, also called the distance effect because of scattering, fully controls the path duration beyond the source distance of 300 km and has a steep gradient compared to the medium effect. Source distance 100-300 km is a transition range of the path duration governing effect from random medium to distance. This means that the scattering may not be the prime cause of peak attenuation and envelope broadening for the source distance of less than 200 km. Furthermore, it is also shown that normal distribution is appropriate for the probability distribution of phase difference, as asserted in the previous studies.

• 대한한의학방제학회지
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• 제31권1호
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• pp.1-10
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• 2023

Objectives : The main aim of this study was to examine the LC-MS/MS used to identify phenolic compounds of CRE(Coptidis Rhizoma 70% EtOH Extract). Also, we investigated antioxidative activities and Anti-inflammatory activities. Methods : LC-MS/MS Analysis HPLC and LC-MS/MS were performed on a 1260 series HPLC system (Agilent Technologies, Inc., California, USA) and 3200 QTrap tandem mass system (Sciex LLC) operated in positive ion mode (spray voltage set at -4.5 kV). The solvent used was DW and Acetonitrile containing 0.1% formic acid, a gradient system was used at a flow rate of 0.5 mL/min for analysis, and a Prontosil C18 column (length, 250 mm; inner diameter, 4.6 mm; particle size, 5 ㎛; Phenomenex Co., Ltd., California, USA, Biochoff Chromatography) was used. The solvent conditions used in the mobile phases were 0-10 min at 10-15% B, 10-20 min at 20% B, 20-30 min at 25%, 30-40 min at 40%, 40-50 min at 70%, 50-60 min at 95%, and 60-70 min at 95%. The analysis was performed at a wavelength of 284 nm and a temperature of 35℃. The cell viability was measured using a 3-(4,5-dimethyethiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity. We examined the effects of CRE on the lipopolysaccharide (LPS)-induced production of nitric oxide (NO) in a RAW 264.7 cells Results : The chemical analysis CRE by Liquid chromatography-tandem mass spectrometry (LC-MS/MS) confirmed that Rosmarinic acid, Ferrulic acid, 3-O-feruloylquinic acid, and 5-O-feruloylquinic acid as phenolic components. DPPH radical scavenging activity was the inhibitory activity of CRE showed at 200 ㎍/mL a statistically significant level. MTT assay demonstrated that the CRE did not have a cytotoxic effect in RAW 264.7 and LPS-induced RAW264.7 cells. Also, CRE reduced NO production in RAW 264.7 cells stimulated with LPS. Conclusions : Based on these findings, The chemical analysis 4 major components CRE such as Rosmarinic acid, Ferrulic acid, 3-O-feruloylquinic acid, and 5-O-feruloylquinic acid. Moreover, we confirmed that CRE has effects antioxidant and anti-inflammatory. The results demonstrate that CRE can be used as an antioxidant and a powerful chemopreventive ingredient against inflammatory diseases.