• Journal of Microbiology and Biotechnology
• /
• 제30권6호
• /
• pp.893-902
• /
• 2020

Propolis is a resinous substance that is collected by Apis mellifera from plant sources and is used in traditional medicine. To study the phytochemical constituents and apoptotic potential of Jordanian propolis extract against different cancer cell lines, propolis was extracted using methanol, hexane, and ethyl acetate and was fractionated using chromatographic methods. Cytotoxicity was assessed using MTT and LDH assays. The apoptotic potential was investigated using florescence microscopy, multicaspase assay, Annexin-V and dead cell assay, and cell cycle assay. The phytochemical constituents were analyzed using GC-MS. The methanol extract of propolis exhibited cytotoxic potential against all cell lines tested. The IC₅₀ values of the methanol extract were 47.4, 77.8, 91.2, and 145.0 ㎍/ml for HepG2, LoVo, MDAMB231, and MCF7 cell lines, respectively. The IC₅₀ values of the F1 fraction were 31.6 (MDAMB231), 38.9 (HepG2), 36.7 (LoVo) and 75.5 (MCF7) ㎍/ml. On further purification using thin-layer chromatography, the IC₅₀ values of the F1-3 fraction were found to be 84.31(HepG2), 79.2 (MCF7), 70.4 (LoVo), and 68.9 (MDAMB231) ㎍/ml, respectively. The anticancer potential of the F1 fraction was confirmed through the induction of apoptosis and cell cycle arrest at the G0/G1 phase. The GC-MS analysis of the F1 fraction revealed the presence of 3-methyl-4-isopropylphenol (29.44%) as a major constituent. These findings indicate the potential of propolis extract as a cancer therapy. However, further investigation is required to assess the acute and subacute toxicity of the most active fraction.

• Journal of Microbiology and Biotechnology
• /
• 제28권5호
• /
• pp.679-687
• /
• 2018

Korean red pine (Pinus densiflora) is one of the major Pinus species in Korea. Red pine bark is removed prior to the chipping process in the wood industry and discarded as waste. However, red pine bark contains a considerable amount of naturally occurring phenolics, including flavonoids, and therefore may have a variety of biological effects. In this study, we investigated if Korean red pine bark extract (KRPBE) could protect neuronal PC-12 cells from oxidative stress and inhibit cholinesterase activity. Analysis of reversed-phase high-performance liquid chromatography results revealed four phenolics in KRPBE: vanillin, protocatechuic acid, catechin, and taxifolin. The total phenolic and flavonoid contents of KRPBE were 397.9 mg gallic acid equivalents/g dry weight (DW) and 248.7 mg catechin equivalents/g DW, respectively. The antioxidant capacities of KRPBE measured using ABTS, DPPH, and ORAC assays were 697.3, 521.8, and 2,627.7 mg vitamin C equivalents/g DW, respectively. KRPBE and its identified phenolics protected against $H_2O_2$-induced oxidative cell death in a dose-dependent manner. Acetylcholinesterase and butyrylcholinesterase, which degrade the neurotransmitter acetylcholine to terminate neurotransmission in synaptic clefts, were inhibited by treatment with KRPBE and its identified phenolics. Taken together, these results suggest that KRPBE and its constituent antioxidative phenolics are potent neuroprotective agents that can maintain cell viability under oxidative stress and inhibit cholinesterase activity.

• 한국분말재료학회지
• /
• 제27권1호
• /
• pp.37-43
• /
• 2020

The Fe-22wt.%Cr-6wt.%Al foams were fabricated via the powder alloying process in this study. The structural characteristics, microstructure, and mechanical properties of Fe-Cr-Al foams with different average pore sizes were investigated. Result of the structural analysis shows that the average pore sizes were measured as 474 ㎛ (450 foam) and 1220 ㎛ (1200 foam). Regardless of the pore size, Fe-Cr-Al foams had a Weaire-Phelan bubble structure, and α-ferrite was the major constituent phase. Tensile and compressive tests were conducted with an initial strain rate of 10^-3/s. Tensile yield strengths were 3.4 MPa (450 foam) and 1.4 MPa (1200 foam). Note that the total elongation of 1200 foam was higher than that of 450 foam. Furthermore, their compressive yield strengths were 2.5 MPa (450 foam) and 1.1 MPa (1200 foam), respectively. Different compressive deformation behaviors according to the pore sizes of the Fe-Cr-Al foams were characterized: strain hardening for the 450 foam and constant flow stress after a slight stress drop for the 1200 foam. The effect of structural characteristics on the mechanical properties was also discussed.

• Journal of Astronomy and Space Sciences
• /
• 제26권4호
• /
• pp.511-520
• /
• 2009

이 연구에서는 GPS(Global Positioning System) 정밀단독측위 기법을 이용하여 해양조석하 중(Ocean Tide Loading, OTL) 분조성분을 검출하고, 그 결과를 조석모델에 의한 예측값과 비교하였다. 고정밀 GPS 자료처리 프로그램인 GIPSY를 사용하여 인천, 서산, 제주 GPS 상시관측소를 대상으로 10분 단위의 수직좌표 시계열을 산출하였으며, 시계열의 조석조화분해를 통해 OTL 지각변위를 일으키는 주요 4대 분조($M_2$, $S_2$, $K_1$, $O_1$)의 진폭과 위상을 검출하였다. 조석모델의 예측값을 기준으로 GPS로 산출한 OTL 분조의 정확도를 평가한 결과 진폭은 제주관측소, 위상은 인천관측소에서 가장 높은 정확도를 나타내었다. 주요 11개 분조 중 최대비율을 차지하는 $M_2$분조의 경우 진폭성분에서 평균 23.8%의 상대오차를 보였다.

• 한국주조공학회지
• /
• 제26권2호
• /
• pp.77-84
• /
• 2006

The effect of alloy composition on the glass forming ability (GFA) of the Ca-rich Ca-Mg-Zn alloys has been investigated in $Ca_{65}Mg_{5+x}Zn_{30-x}$ and $Ca_{55+x}Mg_{15}Zn_{30-x}$ (x=0, 5, 10, 15, 20) alloys. In a wide composition range of 15-25% Zn and 10-20% Mg bulk metallic glass (BMG) samples with the diameter larger than 6 mm are fabricated by conventional copper mold casting method in air atmosphere. Among the alloys investigated, the $Ca_{65}Mg_{15}Zn_{20}$ alloy exhibits the highest GFA enabling to form BMG sample with the diameter of at least 15 mm. The crystalline phase formed during solidification of $Ca_{65}Mg_{15}Zn_{20}$ ($D_{max}=15\;mm$) could be identified as a mixture of $Ca_3Zn$ and $CaMg_2$ cause by the redistribution of the constituent elements on long-range scale. The compressive fracture strength and fracture elongation of the $Ca_{65}Mg_{15}Zn_{20}$ BMG are 602 MPa and 2.08% respectively. The ${\sigma}$ parameter which has been recently proposed for evaluating GFA exhibits better correlation with GFA of Ca-Mg-Zn alloys than other parameters suggested so far such as ${\Delta}T_x$, $T_{rg}$, K, ${\gamma}$, and ${\Delta}T^*$ parameters.

• 한국수자원학회논문집
• /
• 제39권7호
• /
• pp.627-636
• /
• 2006

본 논문에서는 금강수계 오염총량관리 기본계획에서 제시된 오염부하량 자료를 기반으로 공시된 목표수질을 달성하기 위한 적정방류량을 산정하였다. 오염총량관리의 1단계로 BOD를 대상으로 총량관리가 이루어질 계획이며 향후 질소 및 인 계열로 확대될 전망이다. 총량구역별 및 행정구역별로 산정된 BOD와 TN, TP 부하량을 GIS를 활용하여 10개의 지류수계에 대하여 재분배하였고 지류수계에 해당되지 않는 구역에 대해서는 15개의 소구간으로 처리하여 반영하였다. Qual2E를 사용하여 수질모의를 실시한 결과 2010년에 대하여 산정된 장래수질에 대하여 기준부하량의 경우 약 30 CMS의 유량이 본류구간에 대하여 제시된 수질기준을 만족하기에 적절한 것으로 모의되었다.

• 한국세라믹학회지
• /
• 제28권9호
• /
• pp.667-674
• /
• 1991

In this study, Kaolin was carbonized at 1300~175$0^{\circ}C$ and its constituent mineral change was investigated. Carbonized kaolin at 1$650^{\circ}C$ was mixed with metallic silicon, formed and nitrified at 135$0^{\circ}C$ in N2-NH3 atmosphere. Properties of this product such as porosity, bulk density, MOR, nitrization rate and oxidation resistence were measured, and its mineralogical changes were investigated by XRD. The results were as follows; 1) $\beta$-SiC was initially synthesized at 150$0^{\circ}C$, and its amount was continuously increased with reaction temperature to 1$700^{\circ}C$. 2) At 1$600^{\circ}C$, mullite was rapidly decomposed and the amounts of $\beta$-SiC and $\alpha$-Al2O3 were increased simultaneously. 3) By adding alkali to kaolin, the decomposition temperature of mullite was dropped approximately 10$0^{\circ}C$, but the amount of $\alpha$-SiC was increased. 4) The highest values of their nitrization rate and MOR were obtained at the specimen of 35 wt% metallic silicon in nitrization reaction. 5) It seems that increment of $\alpha$-Si3N4 and $\alpha$-Al2O3 phase during nitrization was due to the decomposition of Al4SiC4 existed in carbonized kaolin. 6) Si3N4 bonded SiC-Al2O3 composite were fabricated from kaolin at relatively low temperature (135$0^{\circ}C$).

• 공업화학
• /
• 제4권2호
• /
• pp.349-357
• /
• 1993

Hydroxy-difunctional polyarylate(PAR) 올리고머와 toluene diisocyanate를 반응시켜 합성한 고분자 활성체를 사용하여 ${\varepsilon}$-caprolactam을 음이온 중합하여 다양한 블록길이의 PAR-nylon 6 블록공중합체들을 합성하였다. 합성한 블록공중합체들의 열적성질을 differential scanning calorimeter(d.s.c.)로 측정한 결과, 블록공중합체를 구성하는 PAR 블록과 nylon 6 블록은 부분적 상용성을 가졌으며, 그 정도는 블록의 길이가 짧을수록 컸다. PAR-nylon 6 블록공중합체와 PAR 혹은 nylon 6 homopolymer와의 이원블렌드에서 PAR homopolymer와 PAR 블록, nylon 6 homopolymer와 nylon 6 블록 사이의 분자수준의 섞임을 시사하는 거동을 d.s.c.로 관찰할 수 있었다.

• 한국해안·해양공학회논문집
• /
• 제23권3호
• /
• pp.205-214
• /
• 2011

정밀조석모의를 위한 유한요소 격자가 황해 영역에서 절점밀집도 14 K, 52 K 및 211 K 등으로 세련화되어 구축되었으며, 북서태평양을 포함하는 광역에 대해 57K의 절점을 갖는 격자체계가 구축되었다. 수치실험은 32개의 병렬프로세서에서 pADCIRC v 49.21 모형을 이용하여 수행하였다. 조석모의는 YS-G52K, YS-G211K 격자에서 KorBathy30s와 ETOPO1 수심자료를 적용하고, FES2004로부터 추출된 4 분조를 개방경계에 적용하여 모의한 결과 관측치와는 진폭에서 RMS오차 0.138 m, 위상은 RMS오차 14.80 deg로 이전 황해 연구에 비해 개선된 결과가 나타났다. 북서태평양으로 확장된 영역인 NWP-G57K 격자의 개방경계에서 8 분조를 정의하여 모의한 결과 황해 조석모의 결과와 유사한 매우 만족스러운 결과가 도출되었다.

• 자원리싸이클링
• /
• 제16권4호
• /
• pp.40-46
• /
• 2007

본 연구에서는 건설오니를 이용하여 부가가치가 높은 건설자재로써의 활용을 위한 특성분석 및 고화제의 첨가 재료로 활용하기 위한 슬러지의 재료적 특성 분석에 대해 기술하였다. 본 연구에 사용된 시료는 4개사의 현장에서 다량 발생되는 오니로서 현장에서 발생한 여과 케이크 4종과 여과 전의 슬러리 3종을 사용하였다. 슬러지의 pH, 입도분석, 주사전자현미경 관찰을 수행하였으며, 화학성분은 X선 형광분석기로, 광물상은 X선 회절분석기로 각각 분석 및 동정하였으며 슬러지의 열적 특성 및 가열 중의 휘발 성분의 양은 시차열/중량분석을 실시하여 고찰하였다.