• 한국주조공학회지
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• 제17권6호
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• pp.560-568
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• 1997

The dissolution behavior of secondary solidification phases in squeeze cast Al-3.9wt%Cu-1.5wt%Si-1.0wt%Mg has been studied using a combination of optical microscope, image analyzer, scanning electron microscope(SEM), energy dispersive spectrometer(EDS), X-ray diffractometer(XRD) and differential thermal analyzer (DTA). Special emphasis was placed on the investigation of the effects of the nonequilibrium heat treatment on the dissolution of the second solidification phases. Ascast microstructure consisted of primary solidification product of ${\alpha}-Al$ and secondary solidification products of $Al_2Cu$, $Mg_2Si$ and $Al_2CuMg$. Equilibrium and non-equilibrium solution treatments were carried out at the temperatures of $495^{\circ}C$, $502^{\circ}C$ and $515^{\circ}C$ for 3 to 5 hours. The amount of the dissolved secondary phases increased with increasing solution treatment temperature, for example, area fractions of $Al_2Cu$, $Mg_2Si$ and $Al_2CuMg$ were approximately 0%, 1.6% and 4.2% after solution treatment at $495^{\circ}C$ for 5hours, and were approximately 0%, 0.36% and 2% after solution treatment at $515^{\circ}C$ for 5hours. The best combination of tensile properties was obtained when the as-cast alloy was solution treated at $515^{\circ}C$ for 3hours followed by aging at $180^{\circ}C$ for 10 hours. Detailed DTA and TEM study showed that the strengthening behavior during aging was due to enhanced precipitation of the platelet type fine ${\theta}'$ phase.

• 대한약침학회지
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• 제8권2호
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• pp.23-28
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• 2005

Objective : It has long been known about the osteogenic effect of CTF-HAS on bone tissues. However, it has not been determined the effect of CTF-HAS on cancer cells. The purpose of this study is to screen the CTF-HAS mediated differentially expressed genes in cancer cells such as HepG2 hepatoma cells lines. Methods : CTF-HAS was prepared by boiling and stored at $-70^{\circ}C$ until use. For proteomic analysis, total protein was analyzed by 2D gel electrophoresis and Q-TOF mass spectrometer. Results : In proteomic analysis, three spots were identified by 2D-gel electrophoresis and Q-TOF analysis. One down-regulated protein was heat shock 70kDa protein 5 and up-regulated proteins were chaperonin and 2-phospho -pyruvate-hydratase ${\alpha}-enolase$ by 1.5mg/ml of CTF-HAS. Discussion : Proteomic analysis approach were performed to screen the differential expression genes. The screened genes will be used for the better understanding in therapeutic effect of CTF-HAS on cancer field.

• 한국발생생물학회:학술대회논문집
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• 한국발생생물학회 2003년도 제3회 국제심포지움 및 학술대회
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• pp.90-90
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• 2003

체세포 핵이식에 의한 복제기술은 매우 낮은 성공률 나타내고 있어 실용화에 지장을 초래하고 있다. 이것은 후생적인 유전현상인 reprogramming이 불완전하게 이루어지기 때문인 것으로 추측되어지고 있다(Reik et al., Theriogenology 2003, 59: 21-32; Han et al, Theriogenology 2003, 59: 33-44). 체세포 핵이식 후에 태아사망의 원인이 태반의 비정상적인 기능과 관계가 있는 것으로 추정되는데 복제시 태아사망의 원인을 찾기 위해 본 연구를 시행하였다. 한우에서 체세포 복제 후 임신 말기에 태아가 사망한 태반조직 3개와 IVF 수정란 이식 후 동일한 시기에 제왕절개술을 실시한 태반조직 2개를 실험에 이용하였다. 태반 protein을 Two-Dimensional electrophoresis와 Mass spectrometer를 이용하여 분석 비교하였다. IPG-system을 이용하여 pH 4~7, pH 6~9에서 1차 전기영동을 한 후, 8~l6%의 SDS-PAGE gel에 2차 전기영동을 실시하였고 G-250 Coomassie로 염색하였다. gel 이미지는 Malanie III program을 이용하여 분석하였다. 전체 gel에서 약 1800개의 구분 가능한 protein spot이 나타났다. pH 4~7 범위에서 양적으로 차이나는 것 15개 중 복제한우 태반에서 증가되는 protein spot 5개와 감소하는 protein spot 10개를 골라 protein identification을 실시하였다. MALDI-TOF-MS를 이용하여 동정한 결과 phosphatidylinositol transfer protein-$\alpha$와 interleukin-18 등의 protein이 복제태반에서 발현이 증가되었고, 복제한우에서 발현이 감소되는 것으로는 vimentin, Rho-GDI-$\beta$, TRAST $\beta$-chain, ovarian sterol carrier protein 2, triosephosphate isomerase, tropemyosin beta chain, Aldose reductase 등으로 나타났다. 이러한 protein들은 inositol 지질 신호전달과 면역시스템, 세포분열, 산소 운반, steroidogenic 세포에서의 콜레스테롤 이동, 촉매 작용, 대사 작용 등에 중요한 역할을 하는 것으로 알려져 체세포 복제에 의한 태아사망 원인은 태반에서 이러한 protein들의 비정상적인 발현에 기인된 것으로 추정된다.

• Journal of Radiation Protection and Research
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• 제21권2호
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• pp.91-98
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• 1996

알파방출핵종 존재하에 베타방출핵종인 $^{241}Pu$ 최적 분석조건을 검토하였다. 펄스파고 분석기법을 이용하여 PSA 준위를 설정하였다. $^{241}Pu$ 표준선원을 이용하여 figure of merit가 최대가 되도록 $^{241}Pu$ counting channel를 조정하였고 계측효율이 최대가 되도록 형광체 부피를 설정하였다. 최적화된 $^{241}Pu$ 분석법을 토양과 이끼등의 환경시료에 적용하여 $^{241}Pu$ 방사능농도를 측정하였고. $^{241}Pu/^{239,\;240}Pu$ 방사능 비율로부터 우리나라의 일부 토양 및 이끼에 침적된 Pu의 근원을 규명하였다.

• Toxicological Research
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• 제29권2호
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• pp.115-120
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• 2013

To investigate the effects of short-term exposure of beryllium on the human immune system, the proportion of T-lymphocytes such as CD3+, CD4+, CD8+, CD95, and NK cells, and the proportion of B cells and $TNF{\alpha}$ level in peripheral blood and immunoglobulins in the serum of 43 exposed workers and 34 healthy control subjects were studied. External exposure to beryllium was measured by atomic absorption spectrometer as recommended by the NIOSH analytical method 7300. T lymphocyte subpopulation analysis was carried out with flow cytometer. The working duration of exposed workers was less than 3 months and the mean ambient beryllium level was $3.4{\mu}g/m^3$, $112.3{\mu}g/m^3$, and $2.3{\mu}g/m^3$ in molding (furnace), deforming (grinding), and sorting processes, respectively (cited from Kim et al., 2008). However, ambient beryllium level after process change was non-detectable (< $0.1{\mu}g/m^3$). The number of T lymphocytes and the amount of immunoglobulins in the beryllium-exposed workers and control subjects were not significantly different, except for the total number of lymphocytes and CD95 (APO1/FAS). The total number of lymphocytes was higher in the beryllium-exposed individuals than in the healthy control subjects. Multiple logistic regression analysis showed lymphocytes to be affected by beryllium exposure (odd ratio = 7.293; p<0.001). These results show that short-term exposure to beryllium does not induce immune dysfunction but is probably associated with lymphocytes proliferation.

• 한국약용작물학회지
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• 제19권2호
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• pp.77-82
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• 2011

The antioxidative activity of various enzymatic extracts from Sarcodon aspratus (S. aspratus) was evaluated by measuring 1,1-diphenyl-2-picrylhydrazyl (DPPH), and alkyl radical scavenging activity using an electron spin resonance (ESR) spectrometer. For this study, the S. aspratus were enzymatically hydrolyzed by seven carbohydrases (Viscozyme, Celluclast, Dextrozyme, AMG, Promozyme, Maltogenase, and Termamyl) and eight proteases (${\alpha}$-chymotrypsin, Alcalase, Flavourzyme, Neutrase, papain, pepsin, Protamax, and trypsin). The DPPH radical scavenging activities of Viscozyme and pepsin extracts were the highest, and the half maximal inhibitory concentration ($IC_{50}$) values were 0.896 and 0.734mg/mL, respectively. The Celluclast and trypsin extracts showed the highest scavenging activities on alkyl radical, and their $IC_{50}$ values were 0.278 and 0.575mg/mL, respectively. The Celluclast extracts was decreased cell apoptosis in PC-12 cells against $H_2O_2$-induced oxidative damage. The findings of the present study suggest that enzymatic extracts of S. aspratus exhibit antioxidative activity against oxidative stress on PC-12 cells.

• Journal of Microbiology and Biotechnology
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• 제19권10호
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• pp.1206-1212
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• 2009

Growth rates, photosystem II photosynthesis, and the levels of chlorophyll $\alpha$ and secondary metabolites of Chlorella ovalis were estimated to determine if they were enhanced by the addition of swine urine (BM) or cow compost water (EP) that had been fermented by soil bacteria to deep seawater (DSW) in an attempt to develop media that enabled batch mass culture at lower costs. Growth of C. ovalis in f/2, f/2-EDTA+BM60%, DSW+BM30%, and DSW+EP60% was enhanced and maintained in the log phase of growth for 16 days. The cell densities of C. ovalis in DSW+EP60% ($4.1{\times}10^6$ Cells/ml) were higher than those of f/2 ($2.9{\times}10^6$ Cells/ml), f/2-E+BM60% ($3.7{\times}10^6$ Cells/ml), and DSW+BM30% ($2.7{\times}10^6$ Cells/ml). The growth rate was also more favorable for C. ovalis cultured in DSW+EP60% ($0.15\;day^{-1}$) than that of C. ovalis cultured in the control medium (f/2) ($0.12\;day^{-1}$). Furthermore, the chlorophyll a concentration of C. ovalis cultured in DSW+EP60% (4.56 mg/l) was more than 2-fold greater than that of C. ovalis cultured in f/2 (2.35 mg/l). Moreover, the maximal quantum yields of photo system II at 470 nm (Fv/Fm) were significantly higher in organisms cultured at f/2-E+BM60% (0.53) and DSW+EP60% (0.52) than in the other treatment groups. Finally, Fourier transformation infrared (FT-IR) spectroscopy revealed that C. ovalis grown in DSW+EP60% had more typical peaks and various biochemical pool shifts than those grown in other types of media. Taken together, the results of this study indicate that the use of DSW+EP60% to culture C. ovalis can reduce maintenance expenses and promote higher yields.

• Mass Spectrometry Letters
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• 제4권2호
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• pp.30-33
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• 2013

Chalcones are naturally occurring, biologically active molecules generating interest from a wide range of research applications including synthetic methodology development, biological activity investigation and studying fragmentation patterns. In this article, a series of chalcones has been synthesized and their fragmentation behavior was studied using modern ambient ionization technique Direct Analysis in Real Time (DART). DART ion source connected with an ion trap mass spectrometer was used for the fragmentation of various substituted chalcones. The chalcones were introduced to the DART source using a glass capillary without sample preparation step. All the chalcones showed prominent molecular ion peaks $[M]^{{\cdot}+}$ corresponding to the structures. Multistage mass spectral data $MS^n$ ($MS^2$ and $MS^3$) were collected for all the chalcones studied. The chalcones with substitutions at 3, 4 or 5 positions gave product ion peaks with the loss of a phenyl radical ($Ph^{\cdot}$) by radical initiated ${\alpha}$-cleavage, while substitution at 2 position of chalcone in the A-ring gave a product ion peak with the loss of substituted styryl radical (PhCH = $CH^{\cdot}$). In case of the chalcones with the substituent at 4 positions in A and B rings gave both types of fragmentation patterns. In conclusion, chalcones can be easily characterized using modern DART interface in very short time and efficiently without any cumbersome sample pretreatment.

• Journal of Radiation Protection and Research
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• 제24권1호
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• pp.1-7
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• 1999

기존의 TBP 용매 추출법을 토대로 간단하고 정밀한 환경시료중 우라늄 동위원소 분석법을 개발했다. 질산-불화수소를 가해 토양시료를 분해하였고 TBP와 $CCl_4$등의 유기용매 혼합비율을 조절하여 우라늄을 수층에서 유기 층으로 추출하였으며 8 M HCl를 사용하여 토륨성분을 제거한 후 1 M HCl로 우라늄성분을 유기 층에서 수층으로 역 추출하여 우라늄만을 순수분리하였다. 기존의 전기전착 용액에 DTPA 착화제를 첨가한 새로운 전기전착 용액을 개발하여 최적의 우라늄 전착조건을 설정하였다. 수립된 우라늄 동위원소 분석법을 IAEA Reference 시료에 적용하여 개발된 분석법에 대한 신뢰성을 검증하였다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2011년도 제41회 하계 정기 학술대회 초록집
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• pp.183-183
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• 2011

Multiferroic materials have been widely studied in recent years, because of their abundant physics and potential applications in the sensors, data storage, and spintronics. $BiFeO_3$ is one of the well-known single-phase multiferroic materials with $ABO_3$ structure and G-type antiferromagnetic behavior below the Neel temperature $T_N$ ~ 643 K, but the ferroelectric behavior below the Curie temperature $T_c$~1,103 K. In this study, the $BiFe_{1-x}Ni_xO_3$ (x=0 and 0.05) bulk ceramics were prepared by solid-state reaction and rapid sintering with high-purity $Bi_2O_32$, $Fe_3O_4$ and NiO powders. The powders of stoichiometric proportions were mixed, as in the previous investigations, and calcined at 450$^{\circ}C$ for $BiFe_{1-x}Ni_xO_3$ for 24 h. The obtained powders were grinded, and pressed into 5-mm-thick disks of 1/2-inch diameter. The disks were directly put into the oven, which has been heated up to 800$^{\circ}C$ and sintered in air for 20 min. The sintered disks were taken out from the oven and cooled to room temperature within several min. The phase of samples was checked at room temperature by powder x-ray diffraction using a Rigaku Miniflex diffractometer with Cu K${\alpha}$ radiation. The Raman measurements were carried out by employing a hand-made Raman spectrometer with 514.5-nm-excitation $Ar^+$ laser source under air ambient condition on a focused area of 1-${\mu}m$ diameter. The field-dependent magnetization measurements were performed with a superconducting quantum-interference-device magnetometer.