• 멤브레인
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• 제17권4호
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• pp.311-317
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• 2007

Poly(vinyl alcohol-co-ethylene) (PVA-co-PE)와 poly(styrene sulfonic acid-co-maleic acid) (PSSA-co-PMA)을 고분자 블렌딩 방법으로 50 : 50의 무게비율로써 수소이온 전도성 가교형 전해질막을 제조하였다. PSSA와 PMA이 3 : 1과 1 : 1의 몰 구성비로 되이 있는 두 가지 종류의 PSSA-co-PMA 고분자를 수소이온 전도성 고분자로 사용하였으며, PVA-co-PE 고분자는 에틸렌의 함량이 0, 27 그리고 44 mol%인 고분자를 사용하였다. 전해질 막은 PVA의 히드록실 그룹과 PMA의 카르복시릭 그룹 사이의 에스테르화 반응을 통한 열가교를 통해 제조하였고, FT-IR을 통하여 이를 확인하였다. PSSA-co-PMA의 몰비율이 3 : 1로 구성되어 제조된 전해질막은 몰비율 1 : 1로 구성되어 제조된 막보다 더 낮은 이온교환용량과 더 높은 함수율, 수소이온 전도도를 나타내었다. 또한, 전해질막에서 PE의 함량이 증가할수록 이온교환용량, 함수율, 수소이온 전도도가 계속해서 감소하는 경향성을 보였다. 전해질막의 이러한 물성들은 술폰산기의 함량과 친수성, 막의 가교구조 사이의 경쟁적인 효과로써 설명하였다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1997년도 하계학술대회 논문집 C
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• pp.1252-1254
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• 1997

Direct methanol fuel cell based on a proton-exchange membrane electrolyte was investigated. 60% Pt-Ru/C and 60%Pt/C catalysts were employed for methanol oxidation and oxygen reduction, respectively. Morphologies of the catalysts were investigated by x-ray power diffraction, energy dispersive x-ray spectroscopy, and transmission microscopy. Electrochemical characteristics of the catalysts were tested by using cyclic voltametry technique. I-V characteristics of the fuel cell were tested by changing methanol concentration, temperature, and Nafion type as a proton-exchange membrane electrolyte. AC impedance technique was used to investigate the electrochemical performance of the fuel cell. The performance of single cell was enhance with increasing cell temperature. High operation temperature attributed to the combined effects of the reduction of ohmic resistance and polarization. High cell voltage was obtained from the concentration of 205M methanol. With Nafion 112, a current density of $230mA/cm^2$ at 0.55V was obtained from the concentration of 2.5M methanol.

• Korean Chemical Engineering Research
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• 제54권5호
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• pp.587-592
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• 2016

휴대용 고분자전해질 연료전지의 수소발생용으로써 $NaBH_4$는 많은 장점을 갖고 있다. 본 연구에서는 고농도 $NaBH_4$ 용액에서 비담지 Co-P-B, Co-B 촉매의 $NaBH_4$ 가수분해 특성에 대해 연구하였다. 고농도에서 수소 발생 수율을 높이기 위해 $NaBH_4$ 가수분해 반응의 수소 발생 수율에 미치는 촉매 형태, $NaBH_4$ 농도, 응축수 회수 등의 영향에 대해 실험하였다. Co-P-B 제조과정에서 붕소의 비가 높아질수록 수소 발생 수율이 증가하였다. Co-P:B = 1:5 촉매를 사용해 $NaBH_4$ 수용액 농도를 20 wt%에서 25 wt%로 증가시켰을 때 수소 발생 수율이 감소하였다. Co-P-B와 Co-B 촉매를 같이 사용한 반응기에서 촉매 팩의 두께를 감소시키고 응축수를 회수하여, $NaBH_4$ 25 wt% 수용액으로 최고 수소 발생수율 96.4%를 얻었다.

• Nutrition Research and Practice
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• 제12권1호
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• pp.41-46
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• 2018

BACKGROUND/OBJECTIVES: Exposure of the normal lung tissue around the cancerous tumor during radiotherapy causes serious side effects such as pneumonitis and pulmonary fibrosis. Radioprotectors used during cancer radiotherapy could protect the patient from side effects induced by radiation injury of the normal tissue. Delphinidin has strong antioxidant properties, and it works as the driving force of a radioprotective effect by scavenging radiation-induced reactive oxygen species (ROS). However, no studies have been conducted on the radioprotective effect of delphinidin against high linear energy transfer radiation. Therefore, this study was undertaken to evaluate the radioprotective effects of delphinidin on human lung cells against a proton beam. MATERIALS/METHODS: Normal human lung cells (HEL 299 cells) were used for in vitro experiments. The 3-[4,5-dimethylthiazol-2-yl]-2,5 diphenyl tetrazolium bromide (MTT) assay assessed the cytotoxicity of delphinidin and cell viability. The expression of radiation induced cellular ROS was measured by the 2'-7'-dicholordihydrofluorescein diacetate assay. Superoxide dismutase activity assay and catalase activity assay were used for evaluating the activity of corresponding enzymes. In addition, radioprotective effects on DNA damage-induced cellular apoptosis were evaluated by Western blot assay. RESULTS: Experimental analysis, including cell survival assay, MTT assay, and Western blot assay, revealed the radioprotective effects of delphinidin. These include restoring the activities of antioxidant enzymes of damaged cells, increase in the levels of pro-survival protein, and decrease of pro-apoptosis proteins. The results from different experiments were compatible with each to provide a substantial conclusion. CONCLUSION: Low concentration ($2.5{\mu}M/mL$) of delphinidin administration prior to radiation exposure was radioprotective against a low dose of proton beam exposure. Hence, delphinidin is a promising shielding agent against radiation, protecting the normal tissues around a cancerous tumor, which are unintentionally exposed to low doses of radiation during proton therapy.

• 폴리머
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• 제38권6호
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• pp.801-808
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• 2014

광경화 아크릴고분자 필름에서 이온이동에 관한 연구를 하였다. 고분자에 결합된 아민기와 카르복실산 작용기의 함량을 조절하여 수소이온과 수산화이온의 이동에 적합한 필름을 제조하였다. 수소이온 이동 검출을 위해 p-methylred(PMR) 유도체를 사용하였고 수산화이온 검출을 위해 페놀프탈레인 유도체를 합성하여 각각 고분자에 도입하였다. 수소이온의 이동은 아민기의 함량이 많을수록 빠르게 진행되었고 수산화이온은 카르복실산의 함량이 높을수록 빠르게 이동하였다. 수소이온 이동은 필름표면과 내부로 빠르게 진행하였고 PMR 포함 필름의 흡수스펙트럼을 통해 관찰되었다. 산 용액에 감응하는 필름을 사용하여 색상변화의 가역성을 관찰하였고 연속 50회를 실시하는 동안 정확히 재현되었다. 구리(II) 이온은 카르복실산 작용기의 함량이 높은 필름에서 빠르게 이동하였다. 로다민이 도입된 필름에서 구리이온의 배위로 로다민의 고리열림 반응이 진행되었고 광흡수 및 발광특성 측정을 통해 구리이온의 이동을 추적하였다.

• Journal of Korean Academy of Oral Health
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• 제42권4호
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• pp.224-228
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• 2018

Objectives: As a first step to study the anticaries effect of ethanol alone, we investigated the effects of ethanol on the expression levels of the atpB gene and proton permeability of Streptococcus mutans in suspension cultures. Methods: S. mutans UA159 was grown in brain heart infusion medium at either pH 4.8 or 6.8. The total extracted RNA was reverse-transcribed into cDNA using a $Superscript^{TM}$ First-Strand Synthesis System. The resulting cDNA and negative controls were amplified by ABI PRISM 7700 real-time PCR system with SYBR Green PCR Master Mix. For proton flux assay, bacterial suspensions were titrated to pH 4.6 with 0.5 M HCl, and then additional 0.5 M HCl was added to decrease the pH values by approximately 0.4 units. The subsequent increase in pH was monitored using a glass electrode. Ten percent (v/v) butanol was added to the suspensions at 80 min to disrupt the cell membrane. Results: In a concentration-dependent manner, ethanol alone not only decreased the growth rate of S. mutans and the expression of the atpB gene but also increased the proton permeability at both pH 4.8 and 6.8. Conclusions: These findings suggest that ethanol has the potential for an anticaries ingredient. We believe that ethanol may be used together with fluoride and/or other cariostatic agents in order to develop better anticaries toothpastes and/or mouthrinses.

• Macromolecular Research
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• 제13권4호
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• pp.314-320
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• 2005

Crosslinked poly(vinyl alcohol) (PVA) membranes were prepared at various crosslinking temperatures using poly(acrylic acid-co-maleic acid) (PAM) containing different PAM contents. The thermal properties of these PVA/PAM membranes prepared at various reaction temperatures were characterized using differential scanning calorimetry (DSC). The proton conductivity and methanol permeability of PVA/PAM membranes were then investigated as PAM content was varied from 3 to 13 wt%. It was found that the proton and methanol transport were dependent on PAM content in their function both as crosslinking agent and as donor of hydrophilic -COOH groups. Both these properties decreased monotonously with increasing PAM concentration. The proton conductivities of these PVA/PAM membranes were in the range from $10^{-3}\;to\;10^{-2}S/cm$ and the methanol permeabilities from $10^{-7}\;to\;10^{-6}cm^{2}/sec$. In addition, the effect of operating temperature up to $80^{\circ}C$ on ion conductivity was examined for three selected membranes: 7, 9 and 11 wt% PAM membranes. Ion conductivity increased with increasing operating temperature and showed and S/cm at $80^{\circ}C$, respectively. The effects of crosslinking and ionomer group concentration were also examined in terms of water content, ion exchange capacity (IEC), and fixed ion concentration. In addition, the number of water molecules per ionomer site was calculated using both water contents and IEC values. With overall consideration for all the properties measured in this study, $7{\sim}9\;wt%$ PAM membrane prepared at $140^{\circ}C$ exhibited the best performance. These characteristics of PVA/PAM membranes are desirable in applications related to the direct methanol fuel cell (DMFC).

• 멤브레인
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• 제14권2호
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• pp.117-125
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• 2004

본 연구는 직접메탄을 연료전지(Direct Methanol Fuel Cell)에 적용가능한 양이온교환막 개발에 관한 것으로 PVA/PAM/ZrP 막을 제조하여 PAM, ZrP의 함량 및 농도 변화에 따른 막의 특성을 연구하였다. PVA/PAM/ZrP 막은 PVA에 가교제인 PAM의 함량을 7∼11 wt%로 증가시켜 제조하였으며 그 각각의 막에 8$0^{\circ}C$에서 zirconyl chloride와 Phosphoric acid solution에 침적시켜 제조하였다. ZrP의 농도를 1, 2 M로 변화시켜 메탄을 투과도, 이온전도도, 함수율 및 이온교환용량을 측정하였다. PVA/PAM/ZrP 막의 메탄올 투과도는 10/^{-8}∼l0^{-6}$ $\textrm{cm}^2$/sec, 이온전도도는 $10^{-3}~10^{-2}$ S/cm 정도 나타내었으며 함수율은 0.26∼l.17 g $H_2O$/g membrane, 이온교환용량은 2.59∼5.1 meq/g membrane의 결과를 보였는데 이는 PVA/PAM 막과 비교하여 메탄을 투과도, 이온전도도는 각각 18%, 23% 정도 증가한 것으로 관찰되었다.

• 대한화학회지
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• 제19권4호
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• pp.233-239
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• 1975

세개의 二重結合에 衣하여 conjugate된 비대칭화합물 cis-2-bitenedialdioxime의 두 oxime group의 configuration을 溶媒, 溫度 및 濃度의 影響에 대한 NMR 硏究로서 決定하였다. 溶液狀態에서의 이 化合物은 $-35^{circ}$∼$-95^{\circ}C$의 溫度條件下에서는 항상 "syn-syn" configuration으로 存在함을 알았다. 또한 이 化合物의 oxime group과 溶媒사이의 水素結合의 相對的强度와 溫度 및 濃度에 의 피리딘의 考察하고 몇가지 水素結合의 모델을 提示하였다. 特히 피리딘溶媒 속에서는 水素結合은 한 영향을 窒素가 갖고 있는 非共有電子雙에 衣해서 일어나지 않고, oxime 의 hydroxyl proton과 피리딘의 $\pi$軌道函數 사이에 形成되는 $\pi$-착물의 結果임을 알았다.

• 한국수소및신에너지학회논문집
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• 제24권4호
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• pp.288-294
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• 2013

This gas analysis data come from the hydrogen which is produced by proton exchange membrane. Main impurities of hydrogen are methane, oxygen, nitrogen, carbon monoxide, and carbon dioxide. The concentration of impurities is ranged between 0.0191 to $315{\mu}mol/mol$ for each impurity. Methane contamination is believed from the electrode reaction between carbon doped electrode and produced hydrogen. Nitrogen contamination should take place the sampling process error, not from PEM hydrogen Production system.