• Macromolecular Research
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• 제17권7호
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• pp.528-532
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• 2009

The size and shape of free volume (FV) holes available in membrane materials control the rate of gas diffusion and its permeability. Based on this principle, a segmented, thermo-sensitive polyurethane (TSPU) membrane with functional gate, i.e., the ability to sense and respond to external thermo-stimuli, was synthesized. This smart membrane exhibited close-open characteristics to the size of the FV hole and water vapor permeation and thus can be used as smart food packaging materials. Differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA), positron annihilation lifetimes (PAL) and water vapor permeability (WVP) were used to evaluate how the morphological structure of TSPU and the temperature influence the FV holes size. In DSC and DMA studies, TSPU with a crystalline transition reversible phase showed an obvious phase-separated structure and a phase transition temperature at $53^{\circ}C$ (defined as the switch temperature and used as a functional gate). Moreover, the switch temperature ($T_s$) and the thermal-sensitivity of TSPU remained available after two or three thermal cyclic processes. The PAL study indicated that the FV hole size of TSPU is closely related to the $T_s$. When the temperature varied cyclically from $T_s-10{\circ}C$ to $T_s+10^{\circ}C$, the average radius (R) of the FV holes of the TSPU membrane also shifted cyclically from 0.23 to 0.467 nm, exhibiting an "open-close" feature. As a result, the WVP of the TSPU membrane also shifted cyclically from 4.30 to $8.58\;kg/m^2{\cdot}d$, which produced an "increase-decrease" response to the thermo-stimuli. This phase transition accompanying significant changes in the FV hole size and WVP can be used to develop "smart materials" with functional gates and controllable water vapor permeation, which support the possible applications of TSPU for food packaging.

• 청정기술
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• 제13권1호
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• pp.79-84
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• 2007

본 연구에서는 Ag가 포함된 sulfonated poly(ether ether ketone) (SPEEK)를 촉진 수송 분리막으로 사용하여 에틸렌/에탄 그리고 프로필렌/프로판의 분리연구를 수행하였다. SPEEK는 PEEK를 황산과 반응시켜 제조할 수 있는데, 제조 방법에 따라 다양한 설폰화도 (DS)을 나타내었고 약 70시간 반응시켰을 때 0.95의 DS값을 보여주었다. SPEEK의 농도를 변화시켜 제조된 막은 각각 다른 두께로 코팅됨을 SEM으로 확인하였다. SPEEK막에 Ag 염 수용액을 반응시켜 제조한 SPEEK-Ag 막을 이용하여 에틸렌/에탄 그리고 프로필렌/프로판의 분리 실험을 실시한 결과 에틸렌과 프로필렌은 SPEEK 코팅 두께에 따라 $200{\sim}500$의 선택도를 보여 주었고, 투과도는 $5{\sim}50$ GPU값을 보여 주었다. 또한 SPEEK-Ag 촉진 수송막은 막을 제조할 때 사용한 은염의 종류에 따라서도 각기 다른 분리 효율을 나타내었다.

• Journal of Cancer Prevention
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• 제21권2호
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• pp.95-103
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• 2016

Background: Excess energy supply induces chronic low-grade inflammation in association with oxidative stress in various tissues including intestinal epithelium. The objective of this study was to investigate the effect of high-fat diet (HFD) on intestinal cell membrane integrity and intestinal tumorigenesis in $Apc^{Min/+}$ mice. Methods: Mice were fed with either normal diet (ND) or HFD for 12 weeks. The number of intestinal tumors were counted and biomarkers of endotoxemia, oxidative stress, and inflammation were determined. Changes in intestinal integrity was measured by fluorescein isothiocyanate (FITC)-dextran penetration and membrane gap junction protein expression. Results: HFD group had significantly higher number of tumors compared to ND group (P < 0.05). Blood total antioxidant capacity was lower in HFD group, while colonic 8-hydroxy-2'-deoxyguanosine level, a marker of oxidative damage, was higher in HFD group compared to that of ND group (P < 0.05). The penetration of FITC-dextran was substantially increased in HFD group (P < 0.05) while the expressions of membrane gap junction proteins including zonula occludens-1, claudin-1, and occludin were lower in HFD group (P < 0.05) compared to those in ND group. Serum concentration of lipopolysaccharide (LPS) receptor (CD14) and colonic toll-like receptor 4 (a LPS receptor) mRNA expression were significantly higher in HFD group than in ND group (P < 0.05), suggesting that significant endotoxemia may occur in HFD group due to the increased membrane permeability. Serum interleukin-6 concentration and myeloperoxidase activity were also higher in HFD group compared to those of ND group (P < 0.05). Conclusions: HFD increases oxidative stress disrupting intestinal gap junction proteins, thereby accelerating membrane permeability endotoxemia, inflammation, and intestinal tumorigenesis.

• 분석과학
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• 제28권5호
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• pp.341-346
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• 2015

In order to understand the counter anionic effects in a non-aqueous vanadium redox flow battery (VRFB), we synthesized four types of electrolyte salts (1-ethyltriethamine tertafluoroborate, [E-TEDA]⁺[BF₄]⁻, 1-ethyltriethamine hexafluorophosphate, [E-TEDA]⁺[PF₆]⁻, 1-butyltriethylamine tertafluoroborate, [B-TEDA]⁺[BF₄]⁻, and 1-buthyltriethamine hexafluorophosphate [B-TEDA]⁺[PF₆]⁻) by counter anion exchange reaction after the SN₂ reaction. We confirmed the successful synthesis of the electrolyte salts [E-TEDA]⁺[Br]⁻ and [B-TEDA]⁺[Br]⁻ via ¹H-NMR spectroscopy and GC-mass analysis before the counter anion exchange reaction. The electric potential of the vanadium acetylacetonate, V(acac)₃, as an energy storage chemical was shown to be 2.2 V in the acetonitrile solvent with each of the [E-TEDA]⁺[BF₄]⁻, [E-TEDA]⁺[PF₆]⁻, [B-TEDA]⁺[BF₄]⁻, and [B-TEDA]⁺[PF₆]⁻ electrolyte salts. In a non-aqueous VRFB with a commercial Neosepta AFN membrane, the maximum voltages reached 1.0 V and 1.5 V under a fixed current value of 0.1 mA in acetonitrile with the [E-TEDA]⁺[BF₄]⁻ and [E-TEDA]⁺[PF₆]⁻ electrolyte salts, respectively. The maximum voltage was 0.8 V and 1.1 V under a fixed current value of 0.1 mA in acetonitrile with the [B-TEDA]⁺[BF₄]⁻ and [B-TEDA]⁺[PF₆]⁻ electrolyte salts, respectively. From these results, we concluded that in the non-aqueous VRFB more of the [PF₆]⁻ counter anion than the [BF₄]⁻ counter anion was transported onto the commercial Neosepta AFN anion exchange membrane.

• 멤브레인
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• 제16권3호
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• pp.221-229
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• 2006

본 연구는 불소관능기인 perfluorocyclobutane (PFCB), fluorenyl, sulfonyl계 방향족 화합물을 동시에 포함하는 술폰화된 랜덤 고분자 전해질 막의 제조 및 그 특성에 관한 것이다. 이러한 고분자 전해질 막은 세단계의 합성, 즉 trifluorovinyloxy그룹을 양말단에 포함하는 단량체의 합성, 중부가반응 형태의 열중합, 그리고 chlorosulfonic acid를 이용한 후술폰화를 통하여 얻어졌다. 후술폰화 반응은 고분자 내에 포함된 fluorenyl기의 함량에 따라 일정한 몰비의 술폰화제 비율로 고정하여 진행되었으며, 이에 따라 다양한 이온교환 능력(IEC)을 가지는 고분자를 쉽게 합성할 수 있었다. 제조된 단량체 및 고분자들의 구조와 순도는 각각 FT-IR과 NMR 그리고 질량분석기를 통하여 확인되었다. 술폰화된 fluorenyl기가 많아질수록 술폰화도와 이온교환 능력이 증가하는 것을 확인할 수 있었고 그에 따른 함수율도 역시 증가하는 거동을 보였다. 술폰화된 고분자들의 이온전도도를 측정한 결과 술폰화도가 증가할수록 이온 전도도가 증가하는 것을 관찰할 수 있었다, 이렇게 제조된 전해질막 중 S-1과 S-2의 경우 다양한 온도범위($25{\sim}80^{\circ}C$)에서 상용 전해질막인 Nafion-115를 능가하는 우수한 이온전도도를 나타냈다.

• Archives of Pharmacal Research
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• 제12권2호
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• pp.143-147
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• 1989

The urea effect on skin permeation of clonidine was investigated to reduce a log time and to increase a permeability. ICR mouse skin and human skin were used and were assumed to be a two-layer membrane consisted of stratum corneum and viable epidermis. The urea acted as a skin denaturant and humectant in the whole epidermis. Also it enhanced the skin permeability of clonidine about 3.5 times. On the other hand, it enhanced the skin permeability by acting as a humectant in the viable epidermis. But the urea effect on the whole epidermis was shown to be greater than that on the viable epidermis. Therefore, it was found that the effect of urea was greater on the stratum corneum than the viable epidermis. Variation of enhancing effect according to the concentration of urea was not found in the range of 1% to 20%.

• Macromolecular Research
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• 제12권6호
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• pp.593-597
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• 2004

A new ionomeric polymer-metal composite (IPMC) was prepared using a cast membrane of acrylic copolymer, which was synthesized by radical copolymerization of fluoroalkyl acrylate and acrylic acid (AA). To examine its performance as a new electroactive polymer, the current and displacement responses to a step voltage applied across the IPMC were measured. The largest responses were observed when the AA content in the copolymer was $10.6\;wt\%$.

• Bulletin of the Korean Chemical Society
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• 제25권7호
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• pp.1055-1060
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• 2004

A new inhibitor for peptidylprolyl cis-trans isomerase (PPIase) has been isolated from Ganoderma lucidum and purified to homogeneous state by organic solvent extraction. The purified PPIase inhibitor (GPI) is assumed to be a membrane-associated glycoprotein. GPI inhibits specifically the bovine brain PPIase, a cyclophilin, and has no effect on the FKBP activity. The results of our chemical modification study of GPI indicate the presence of Lys residue(s) at or near its binding site. Like CsA-cyclophilin complex, GPI-bovine brain PPIase complex strongly inhibits the calcineurin activity in vitro, suggesting the possible involvement of GPI in immunomodulating pathway by the formation of PPIase-inhibitor-calcineurin complex.

• 한국섬유공학회:학술대회논문집
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• 한국섬유공학회 2002년도 봄 학술발표회 논문집
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• pp.459-461
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• 2002

A new class of materials based on organic and inorganic species combined at a molecule level has obtained more attention recently[1]. HPA(heteropolyacid) shows unmatched applied perspective in terms of synthesis chemistry, analysis chemistry, biology, medicine and materials science[2]. As a potential photochemical material, the hybrid system of HPA and polymer has been investigated. However, the design and synthesis of heteropolyacid-based hybrids, which are at the forefront of the materials chemistry research, is still in its infancy. (omitted)

• BMB Reports
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• 제30권3호
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• pp.229-233
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• 1997

Indolicidin has been known to have a broad spectrum of antimicrobial activities against Gram negative and positive bacteria. Its eight analogues were chemically synthesized. The analogue design was based on the analysis of sequence to elucidate the role of some residues in the antibacterial mechanism of indolicidin. Bactericidal activities were assayed against Escherichia coli and Proteus vulgaris, and the membrane perturbing abilities of the peptides were assayed using a dye containing liposome. Among the eight analogues, $[Gly^4, Gly^6]-Indo,\;[Ile^6,Ile^8]-Indo,\;[Lys^{12}]-Indo$ and $[Thr^2,Tyr^9]-Indo$ showed enhanced antibacterial activities. These results suggest that proline and cationic residues are important in the bactericidal activity of indolicidin. We tried to describe the antimicrobial mechanism of indolicidin with these results.