• Elastomers and Composites
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• 제51권1호
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• pp.63-67
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• 2016

Poly(ethylene-co-vinyl acetate) (EVA) was pyrolyzed to eliminate acetic acid of VA unit using off-line pyrolysis, and the deacetylated EVA was analyzed infrared spectroscopy (IR) and pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS). EVA film for deacetylation was prepared by solution casting on aluminum foil and it was pyrolyzed at low temperature of $300^{\circ}C$ in the off-line pyrolysis apparatus. After deacetylation, carbon-carbon double bond (C=C) was formed by 1,2-elimination of the VA unit in the EVA backbone. Most of C=C bonds were trans-1,4-unit and 1,2-unit was also observed. Presence of the 1,2-unit in deacetylated EVA indicates that terminal or branch VA units exist in the raw EVA. Py-GC/MS chromatogram of deacetylated EVA displayed much smaller acetic acid and much more abundant other pyrolysis products than that of raw EVA, which means that the pyrolysis efficiency and separation condition were improved.

• IMMUNE NETWORK
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• 제1권1호
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• pp.26-31
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• 2001

Background : Follicular dendritic cells (FDCs) play key roles during T cell-dependent humoral immune responses by allowing antigen-specific B cells to survive, proliferate, and differentiate within the FDC networks of secondary follicles, i.e., germinal centers (GC). Methods: A novel monoclonal antibody, 3C8, was generated by immunizing with an FDC line HK, in order to understand the molecular signals involved in the FDC-B cell interactions in the microenvironment of the GC. Results: The 3C8 antibody did not bind to mononuclear cells, including T cells, B cells, and monocytes. Murine L929 and human skin fibroblasts exhibited no or little reactivity to 3C8. However, 3C8 specifically recognized HK cells by flowcytometry. Furthermore, the antigen recognized by 3C8 was restricted to the GC of the human tonsil. Dendritic networks of the GC were intensely stained by 3C8, but cells outside the GC were not. Conclusion: Our results suggest that the antigen 3C8 may play some unique role on FDCs during the GC reactions.

• 천문학회보
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• 제44권2호
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• pp.49.2-49.2
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• 2019

We present results from our long-term observing campaign, using the NASA IRTF at Maunakea, to obtain 2 - 4 ㎛ spectra of 118 red point sources in the line of sight to the Galactic Center (GC). Our sample is largely composed of point sources selected from near- and mid-infrared photometry, but also includes a number of massive young stellar objects. Many of these sources show high foreground extinction as shown by deep 3.4 ㎛ aliphatic hydrocarbon absorption feature, which is a characteristic of the diffuse ISM and comes from the long line of sight through the diffuse medium toward the Central Molecular Zone (CMZ), the central 300 pc region of the GC. The deep 3.1 ㎛ H₂O ice absorption band coming from the local, dense material in the GC CMZ suggests that most sources are likely located in the GC CMZ. A few of these sources show weak CCH₃OH ice absorption at 3.535 ㎛, which can provide a strong constraint on the CCH₃OH ice formation in the unique environment of the CMZ. From the best-fitting models, the optical depths of these features are determined and used to generate a well-rounded view of the ice composition across the GC CMZ and the spectral characteristics of massive YSOs in the GC.

• Journal of Gastric Cancer
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• 제23권1호
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• pp.207-223
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• 2023

Gastric cancer (GC) is the fourth leading cause of cancer-related deaths worldwide. Under the standard of care, patients with advanced GC (AGC) have a median survival time of approximately 12-15 months. With the emergence of immunotherapy as a key therapeutic strategy in medical oncology, relevant changes are expected in the systemic treatment of GC. In the phase III ATTRACTION-2 trial, nivolumab, a monoclonal anti-programmed cell death 1 (PD-1) antibody, as a third- or later-line treatment improved overall survival (OS) compared with placebo in patients with AGC. Furthermore, nivolumab in combination with 5-fluorouracil and platinum as a first-line treatment improved OS in patients with human epidermal growth factor receptor-2 (HER2)-negative AGC in the global phase III CheckMate-649 study. Another anti-PD-1 antibody, pembrolizumab, in combination with trastuzumab and cytotoxic chemotherapy as a first-line treatment, significantly improved the overall response rate in patients with HER2-positive AGC. Therefore, immune checkpoint inhibitors (ICIs) are essential components of the current treatment of GC. Subsequent treatments after ICI combination therapy, such as ICI rechallenge or combination therapy with agents having other modes of action, are being actively investigated to date. On the basis of the success of immunotherapy in the treatment of AGC, various clinical trials are underway to apply this therapeutic strategy in the perioperative and postoperative settings for patients with early GC. This review describes recent progress in immunotherapy and potential immunotherapy biomarkers for GC.

• 한국대기환경학회지
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• 제21권1호
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• pp.107-118
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• 2005

In this study, the concentrations of major odorous compounds including reduced sulfur compounds (OMS, CS$_2$, and DMDS) and aromatic VOC (benzene, toluene, xylene, etc.) were measured continuously using an on-line GC analytical system. Our measurements were made from a residential area of Ansan sity during about two week period of October, 2004. The highest mean concentrations of Sand VOC were found as 56.9 pbb of DMS and 21.7 ppb of toluene, respectively. The results of this study generally show that the pollution levels for both types of chemicals are significant relative to previous measurement results reported from comparable sites, if the results are compared simply in terms of the magnitude of the measured concentration data. Moreover, when the relative importance of different compounds is compared in terms of the odor strength, it indicated that the contribution of reduced S compounds may be much more important than that of VOC in the study area.

• 한국대기환경학회지
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• 제25권6호
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• pp.523-538
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• 2009

Recently, there has been a keen demand for real-time automatic monitoring of VOCs not only in Korea but other developed countries. We carried out this study to evaluate and to optimize the performance of a continuous automatic monitoring system for hazardous VOCs (HVOCs) in the ambient atmosphere, using an on-line GC system. The online system normally consisted of a Nafion dryer prior to a cold trap of an automatic thermal desorption apparatus and a GC system equipped with two detectors, i.e. PID and ECD. Preliminary tests conducted to check out any contamination of the system revealed an evidence of significant artifact formation of benzene, and it was found that the Nafion dryer (even brand new one) is the source of the benzene artifact. Thus, all the subsequent experiments in this study was carried out inevitably by removing the Nafion dryer. The on-line GC method was investigated with a variety of QC/QA performance criteria such as repeatability, linearity, lower detection limits, and accuracy. In order to find out the best operating condition for the on-line GC system, three different types (in terms of adsorption strength) of cold trap combinations were tested, i.e. (i) Tenax-TA and Carbopack-B combination (weak and hydrophobic); (ii) Tenax-TA, Carbopack-X and Carboxen-1000 combination (strong and hydrophilic); and (iii) Tenax-TA and Carbopack-X combination (medium and hydrophobic/hydrophilic). The USEPA TO-17 manual method was selected as a reference method to evaluate the performance of the on-line method. A series of experiments revealed that the system performance was superior to others when a cold trap packed with hydrophilic adsorbents (Tenax-TA/Carbopack-X/Carboxen-1000 combination) was used and operated at $25^{\circ}C$. However, the system with a cold trap packed with a combination of Tenax-TA and Carbopack-X is more recommended for field applications since the carboxen-1000 adsorbent is too sensitive to water vapor, and hence the performance of the system might be very unstable to humid samples or during rainy days. Furthermore, the precision and accuracy criteria of the Tenax-TA/ Carbopack-X combination were generally compatible with the triple adsorbents cold trap. The continuous automatic monitoring method is, thus, considered very useful to real-time monitoring to understand the variations of VOCs concentrations in ambient air, as it adopts much simpler procedures in sampling, analysis, and data integration steps than manual monitoring methods. However, it should be noted that there is a high possibility of benzene artifacts formation through the Nafion dryer, which is often installed to remove water vapor in air samples before being adsorbed onto the cold trap. Therefore, if a Nafion dryer is used in any studies of monitoring VOCs, the benzene contamination should be carefully examined before carrying out obtaining the data.

• 천문학회보
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• 제38권2호
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• pp.36-36
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• 2013

Globular clusters (GCs) are among the oldest stellar objects in the universe and provide valuable constraints on many aspects of galaxy evolution. GC systems typically exhibit bimodal color distributions the phenomenon of which has been a major topic in the area of GC research. GC color bimodality established a paradigm where scenarios to explain its origin require two GC groups with different formation origins. The GC division, asserted mainly by photometric color bimodality so far, has been viewed as the presence of two distinct metallicity subgroups within individual galaxies. In this study, we make use of spectroscopy of GC systems associated with two giant galaxies, M31 (the Andromeda) and M87 (NGC 4486), to investigate the GC bimodality and the underlying metallicity distributions. Recent spectroscopy on the globular cluster (GC) system of M31 with unprecedented precision witnessed a clear bimodality in absorption-line index distributions of old GCs. Given that spectroscopy is a more detailed probe into stellar population than photometry; the discovery of index bimodality may point to the very existence of dual GC populations. However, here we show that the observed spectroscopic dichotomy of M31 GCs emerges due to the nonlinear nature of metallicity-to-index conversion and thus one does not necessarily have to invoke two separate GC subsystems. We present spectra of 130 old globular clusters (GCs) associated with the Virgo giant elliptical galaxy M87, obtained using the Multi-Object Spectrography (MOS) mode of Faint Object Camera and Spectrograph (FOCAS) on the Subaru telescope. M87 GCs with reliable metallicity measurements exhibit significant inflection along the color-metallicity relations, through which observed color bimodality is reproduced from a broad, unimodal metallicity distribution. Our findings lend further support to this new interpretation of the GC color bimodality, which could change much of the current thought on the formation of GC systems and their host galaxies.

• 한국대기환경학회:학술대회논문집
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• 한국대기환경학회 2005년도 추계학술대회 논문집
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• pp.356-358
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• 2005

• 보존과학회지
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• 제33권5호
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• pp.345-354
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• 2017

전남 진도군 소재 사찰의 보수 공사 중 벽화가 발견되어 제작기법 파악을 위해 교착제로 사용된 물질을 확인하고자 하였다. 이에 해당 벽화 시편에 대해 열분해/GC/MS와 IR 분석을 실시하였으며, 열분해/GC/MS분석은 직접 열분해와 온라인 메틸화법을 도입하였다. IR 분석에서 아교, 옻, 황칠 등 전통 교착제와 초산아크릴계 수지의 스펙트럼을 벽화시편과 비교했을 때 유사하지 않았으며, 건성유인 아마인유와 비교했을 때도 유사도가 낮았다. 벽화시편의 열분해/GC/MS 분석 결과를 옻, 황칠, 아교, 초산아크릴수지와 비교했을 때 이들 물질이 아닌 것으로 나타났다. 한편, 벽화시편에서 팔미트산, 옥타데칸산, nonanedioic acid, 옥타데센산 등 건성유에 특징적인 물질이 검출되었고, 경화 건성유와 유사한 열분해/GC/MS 크로마토그램이 관찰되었다. 따라서, 벽화는 건성유를 교착제로 사용하여 제작된 것으로 판단되었다.

• Journal of Nutrition and Health
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• 제31권4호
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• pp.799-808
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• 1998

To investigate the antitumor activity of mugwort (Artemisia princeps Pampan), petroleum ether extract of mugwork was partially purified by a silica gel chromatography. Among several fractions, the fraction which was obtained under the elution with acetone, showed potent cytotoxicity against mouse leukemia cell line(Ll210), human colon cancer cell line (HCT-48) and human hepatoma cell line (Hep G2) , but was less effective with normal cell line(mouse embryo cell). Acetone fraction appeared to be glycolipid by Benedict test and the major fatty acids of the lipid were C16 ; 0 , C 18: 3by GC/MS analysis.