• 분석과학
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• 제34권1호
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• pp.23-35
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• 2021

In order to measure the volatile organic compounds (VOCs) of a sample which is too large to use commercially available chamber, a stainless steel vacuum chamber (VC) (with an internal diameter of 205 mm and a height of 50 mm) was manufactured and the temperature of the chamber was controlled using an oven. After concentrating the volatiles of the sample in the chamber by helium gas, it was made possible to remove residual volatile substances present in the chamber under reduced pressure ((2 ± 1) × 10-2 mmHg). The chamber was connected to a purge & trap (P&T) using a 6 port valve to concentrate the VOCs, which were analyzed by gas chromatography-mass spectrometry (GC-MS) after thermal desorption (VC-P&T-GC-MS). Using toluene, the toluene recovery rate of this device was 85 ± 2 %, reproducibility was 5 ± 2 %, and the detection limit was 0.01 ng L-1. The method of removing VOCs remaining in the chamber with helium and the method of removing those with reduced pressure was compared using Korean drinking water regulation (KDWR) VOC Mix A (5 μL of 100 ㎍ mL-1) and butylated hydroxytoluene (BHT, 2 μL of 500 ㎍ mL-1). In case of using helium, which requires a large amount of gas and time, reduced pressure ((2 ± 1) × 10-2 mmHg) only during the GC-MS running time, could remove VOCs and BHT to less than 0.1 % of the original injection concentration. As a result of analyzing volatile substances using VC-P&T-GC-MS of six types of cell phone case, BHT was detected in four types and quantitatively analyzed. Maintaining the chamber at reduced pressure during the GC-MS analysis time eliminated memory effect and did not affect the next sample analysis. The volatile substances in a cell phone case were also analyzed by dynamic headspace (HT3) and GC-MS, and the results of the analysis were compared with those of VC-P&T-GC-MS. Considering the chamber volume and sample weight, the VC-P&T configuration was able to collect volatile substances more efficiently than the HT3. The VC-P&T-GC-MS system is believed to be useful for VOCs measurement of inhomogeneous large sample or devices used inside clean rooms.

• Journal of Ginseng Research
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• 제39권1호
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• pp.46-53
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• 2015

Background: Glucocorticoids (GCs) are commonly used in many chemotherapeutic protocols and play an important role in the normal regulation of bone remodeling. However, the prolonged use of GCs results in osteoporosis, which is partially due to apoptosis of osteoblasts and osteocytes. In this study, effects of Korean Red Ginseng (KRG) on GC-treated murine osteoblastic MC3T3-E1 cells and a GC-induced osteoporosis mouse model were investigated. Methods: MC3T3-E1 cells were exposed to dexamethasone (Dex) with or without KRG and cell viability was measured by the 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) assay. Realtime polymerase chain reaction was performed to evaluate the apoptotic gene expression; osteogenic gene expression and alkaline phosphatase (ALP) activity were also measured. Western blotting was performed to evaluate the mitogen-activated protein kinase (MAPK) proteins. A GC-induced osteoporosis animal model was used for in vivo study. Results and conclusion: The MTT assay revealed that Korean Red Ginseng (KRG) prevents loss of cell viability caused by Dex-induced apoptosis in MC3T3E1 cells. Real-time polymerase chain reaction data showed that groups treated with both Dex and KRG exhibited lower mRNA levels of caspase-3 and -9, whereas the mRNA levels of Bcl2, IAPs, and XIAP increased. Moreover, groups treated with both Dex and KRG demonstrated increased mRNA levels of ALP, RUNX2, and bone morphogenic proteins as well as increased ALP activity in MC3T3-E1 cells, compared to cells treated with Dex only. In addition, KRG increased protein kinase B (AKT) phosphorylation and decreased c-Jun N-terminal kinase (JNK) phosphorylation. Moreover, microcomputed tomography analysis of the femurs showed that GC implantation caused trabecular bone loss. However, a significant reduction of bone loss was observed in the KRG-treated group. These results suggest that the molecular mechanism of KRG in the GC-induced apoptosis may lead to the development of therapeutic strategies to prevent and/or delay osteoporosis.

• 동의생리병리학회지
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• 제19권1호
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• pp.81-86
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• 2005

The purpose of this study is to examine the antioxidant activity in the germ cells of the extract of Psoraleae fructus. The extract was studied for dipheny-picryl-hydrazyl (DPPH) radical scavenging activity, GC-1 cell viability by a modified MTT assay, the effects on $H_2O_2$-induced cytotoxicity by MTT assay and lipid perixidation by malondialdehyde (MDA) formation, respectively. The results showed that the extract scavenged DPPH radical with the IC50 being 0.427 mg/mL. The extract was dose-dependent in growth of GC-1 cell. $H_2O_2$-induced cytotoxicity (67.7 %) was blocked by the extract concentration- dependently. Furthermore, the extract also displayed a dose-dependent reduction of MDA formation on $H_2O_2$-induced lipid peroxidation. In conclusion, the extract of Psoraleae fructus has potent antioxidant activity.

• The Journal of Advanced Prosthodontics
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• 제7권1호
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• pp.21-26
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• 2015

PURPOSE. To evaluate the cytotoxicity of temporary luting cements on bovine dental pulp-derived cells (bDPCs). MATERIALS AND METHODS. Four different temporary cements were tested: Rely X Temp E (3M ESPE), Ultratemp (Ultradent), GC Fuji Temp (GC), and Rely X Temp NE (3M ESPE). The materials were prepared as discs and incubated in Dulbecco's modified eagle's culture medium (DMEM) for 72 hours according to ISO 10993-5. A real-time cell analyzer was used to determine cell vitality. After seeding $200{\mu}L$ of the cell suspensions into the wells of a 96-well plate, the bDPCs were cured with bioactive components released by the test materials and observed every 15 minutes for 98 hours. One-way ANOVA and Tukey-Kramer tests were used to analyze the results of the proliferation experiments. RESULTS. All tested temporary cements showed significant decreases in the bDPCs index. Rely X Temp E, GC Fuji Temp, and Rely X Temp NE were severely toxic at both time points (24 and 72 hours) (P<.001). When the cells were exposed to media by Ultratemp, the cell viability was similar to that of the control at 24 hours (P>.05); however, the cell viability was significantly reduced at 72 hours (P<.001). Light and scanning electron microscopy examination confirmed these results. CONCLUSION. The cytotoxic effects of temporary cements on pulpal tissue should be evaluated when choosing cement for luting provisional restorations.

• Nuclear Engineering and Technology
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• 제53권3호
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• pp.927-931
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• 2021

In this work, an attempt is made to improve the electrochemical corrosion resistance of Zircaloy-4 by helium ions implantation. For this purpose, the Zircaloy-4 was implanted with 300 keV helium ions of fluences 1 × 10¹³, 1 × 10¹⁵, and 1 × 10¹⁶ ions-cm^-2 by using Pelletron Accelerator. Electrochemical tests of pristine and ion-implanted samples were performed in NaCl solution and their potentiodynamic polarization curves were obtained. The results showed enhancement of the corrosion resistance of Zircaloy-4 after helium ions implantation. The corrosion rate and current density of the material were significantly reduced by the helium implantation. The decrease in corrosion parameters was attributed to helium ions diffusion inside Zircaloy-4 that reduced the electrons flow from the samples.

• 한국주조공학회지
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• 제7권1호
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• pp.53-59
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• 1987

In order to study the infuence of Sb addition on the compacted vermicular graphite cast iron(C/V) and gray cast iron(GC), these specimen which had different Sb content(0-0, 1wt.%) were prepared. these specimen were tested for microstructure and mechanical properties. The result from this study are as follows. For C/V and GC, the microstructure of graphite appeared to be finer with increasing Sb content more than 0.06wt.% Ferrite disappeared from the matrix with addition of Sb more than 0.06wt.% in GC and more than 0.08wt.% in C/V. The size of the eutectic cell in GC was 4.5 to 7 times larger than that in C/V, but the decreasing tendancy of its size was more remarkable in GC than in C/V with increasing Sb content. The abrasion speed corresponding to the maximum amount of abrasion in the nabrasion test was found to be 1.37m/sec. GC sample weared 3.6 to 21 times faster than those of C/V did. the amount of abrasion demeased remarkably with Sb addition, and the abrasion rate was constant with Sb content over 0.04wt.%

• 동의생리병리학회지
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• 제19권6호
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• pp.1541-1545
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• 2005

The purpose of this study is to examine the antioxidant activity in the germ cells of the extract of Corm fructus. The extract was studied for diphenyl-picryl-hydrazyl (DPPH) radical scavenging activity, GC-1 cell viability by a modified MTT assay, the effects on $H_2O_2$-induced cytotoxicity by MTT assay and lipid perixidation by malondialdehyde (MDA) formation, respectively. The results showed that the extract scavenged DPPH radical with the IC50 being $200{\mu}g/mL$. The extract at concentrations of $10-500{\mu}g/ml$ showed dose-dependent in growth of GC-1 cell. $H_2O_2$-induced cytotoxicity (63.0%) was blocked by the extract (10, 50, 100, 250 and $500{\mu}g/ml$) concentration-dependently. Furthermore, the extract (50, 100 and $250{\mu}g/ml$) also displayed a dose-dependent reduction of MDA formation on $H_2O_2$-induced lipid peroxidation. In conclusion, the extract of Corm fructus has potent antioxidant activity.

• International Journal of Automotive Technology
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• 제8권1호
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• pp.119-126
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• 2007

Because of the low temperature operation, proton exchange membrane (PEM) fuel cell has a water phase transition. Therefore, water management is an important operation issue in a PEM fuel cell because the liquid water in the fuel cell causes electrode flooding that can lower the cell performance under high current density conditions. In this study, in order to understand the reactant distributions in the cathode channels of the PEM fuel cell, an experimental technique that can measure the species concentrations of reactant gases by using gas chromatograph (GC) is applied for an operating PEM fuel cell. The oxygen distribution along the cathode flow channels of PEM fuel cell is mainly investigated with various operating conditions. Also, the relations between cathode flooding and oxygen concentrations and oxygen consumption pattern along the cathode channel configurations of the unit cell adopted for this study are discussed using GC measurement and visualization experiment of cathode flooding. It is found that the amount of oxygen consumption is very sensitive to various operating conditions of the fuel cell and was much affected by the flooding occurrence in cathode channels.

• Clinical and Experimental Reproductive Medicine
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• 제24권2호
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• pp.267-271
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• 1997

Apoptosis, programmed cell death, is posulated to occur in granulosa cells in ovarian follicular atresia. bcl-2 gene serves as protector from apoptosis and, thus, is associated with increased cell survival. TRPM-2 gene expression has been implicated as a trigger of apoptosis in rat prostate, uterus and mammary gland. Our objective was to determine if bcl-2 and TRPM-2 are expressed in luteinized human GC and, therefore, have regulatory functions for apoptosis in GC. Human GC were obtained via oocyte retrival from the infertile patients stimulated with exogeneous gonadotropins while undergoing IVF. GC were isolated from follicular fluid using Percoll gradient centrifugation. The GC were further purified with anti-CD45 magnetic beads to remove contaminating WBC's. RT-PCR were performed to analyze the mRNA expression of bcl-2 and TRPM-2 in the GC. The PCR primers were designed to amplify a 195 bp fragment of bcl-2 and a 174 bp fragment of TRPM-2. The PCR products were electrophoresed on 4% agarose gel. Three separate experiments indicated that both bcl-2 and TRPM-2 are concurrently expressed in human GC. We cultured granulosa cells with FSH (1 ng/ml) for 1 day to investigate the relative changes of TRPM-2 mRNA level with RNAse protection assay. When we cultured GC with serum free medium for 1 day TRPM-2 mRNA level increased with 1.3 fold, however it was decreased 0.64 fold with FSH. Therefore we conclude that bcl-2 and TRPM-2 are concurrently expressed and that the interaction of their products may be involved in GC apoptosis. And TRPM-2 may be regulated with FSH.

• 한국미생물·생명공학회지
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• 제41권3호
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• pp.272-277
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• 2013

본 연구에서는 gas chromatography/mass spectrometry (GC/MS)와 gas chromatography (GC)를 이용하여 주목 식물세포 Taxus chinensis 유래 타르 성분을 최초로 동정/정량하였다. 또한 식물세포배양으로부터 항암물질 paclitaxel 정제를 위한 전처리 과정에서 이들 타르 성분들의 제거 양상을 확인하였다. GC/MS 분석을 통하여 체류시간을 비교한 결과, 5종류의 타르성분이 체류시간 6.374, 8.208, 15.209, 20.045, 24.474분에서 각각 2-picoline, o-xylene, 2,5-xylenol, 1-methylnaphthalene, acenaphthene이 동정되었다. 또한 표준물질을 이용한 spike testing을 수행한 결과 동일 물질임을 재확인 하였다. GC 분석을 통하여 동정된 5종류 타르성분을 정량한 결과, 메탄올 추출물에 총 0.6805 wt% (2-picoline: 0.2512 wt%, 2,5-xylenol: 0.1586 wt%, acenaphthene: 0.1240 wt%, 1-methylnaphthalene: 0.0942 wt%, o-xylene: 0.0525 wt%) 타르 성분이 존재하였다. 액-액 추출을 수행한 결과, 메탄올 추출물 시료 내 총 타르 성분의 양 대비 42%의 타르 성분이 제거됨을 확인할 수 있었다. 1-Methylnaphthalene, acenaphthene, 2,5-xylenol, 2-picoline의 경우에는 각각 75.90, 59.92, 35.94, 29.74%로 높은 제거율을 보인 반면 oxylene의 경우에는 10.86%의 제거율로 상대적으로 적게 제거됨을 알 수 있었다. 흡착제 처리 후 2-picoline과 o-xylene의 양도 상당히 줄었지만 이들 2 종류의 타르 성분을 제외한 나머지 세 종류의 타르 성분(2,5-xylenol, 1-methylnaphthalene, acenaphthene)은 완전히 제거됨을 확인할 수 있었다. 흡착제 처리 공정에서 제거되지 않은 두 종류의 타르 성분(2-picoline, o-xylene)은 헥산 침전 공정에 의해 완전히 제거 가능하였다.