• 멤브레인
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• 제17권1호
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• pp.44-53
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• 2007

본 연구에서는 나노여과막과 역삼투막의 표면 개질을 통하여 유량의 향상 및 내오염성을 향상시키는 제조 방법을 개발하였다. 실란 화합물이 코팅된 복합막의 표면 성질이 막 오염 지수 MFI 값에 미치는 영향을 살펴보았다. 상용화된 역삼투막(RE1812-LP)과 나노여과막(ESNA 4040-LF) 복합막을 기저막으로 사용하여 실란 커플링제의 농도를 달리하여 개질 복합막을 제조하였다. 실란 커플링제 aminopropylmethoxydiethoxysilane은 아민 관능기와 3개의 알콕시 관능기를 가지며 아민 관능기가 가지는 친수성 특성이 개질막의 투과 수량 및 내오염성에 미치는 영향을 조사하였다. 개질막의 실란층의 안정적인 형성을 확인하기 위하여 FE-SEM, 접촉각 측정 및 제타 전위값 등의 표면 특성 변화를 살펴보았다. 특히 개질된 나노여과막의 2가 이온 수용액을 공급수로 할 경우 염제거율에 대한 영향 없이 내오염성이 현저히 증가함을 확인하였다.

• 보존과학회지
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• 제26권3호
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• pp.325-334
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• 2010

이 연구에서는 석조문화재 강화제의 처리 효과를 정량적으로 규명하기 위해 화강석분과 포틀랜드시멘트를 이용하여 강도가 낮은 인공 다공질 시료를 제작하고, 여기에 4종의 알콕시실란계 강화제와 아크릴수지, 에폭시수지 등 상업화 된 6종의 강화제를 적용하여 처리 전과 후의 특성을 비교 분석하였다. 실험 결과, Silres BS OH 100은 밀도 및 표면 경도 향상에 효과적이며, 발수성의 SS-101과 친수성의 Site SX-RO는 염풍화에 대해 향상된 내구성을 보였다. Araldite 2020은 물리적 기능 향상에 가장 효과적이나, Syton HT-50 및 Paraloid B72는 낮은 침투율로 인해 표면 일부에 처리효과가 집중되어 전체적으로는 풍화에 취약한 것으로 나타났다.

• Korean Chemical Engineering Research
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• 제43권1호
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• pp.176-180
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• 2005

방향족 Schiff base 메소제닉 단위와 폴리메틸렌 유연격자로 이루어진 한 계열의 주사슬 액정중합체와 네 계열 화합물의 액정성을 살펴보았다. 이들의 열적 성질과 액정성은 시차 주사 열분석기와 가열판이 부착된 편광현미경에 의하여 조사하였다. 중합체와 화합물 액정상의 성질은 중앙 폴리메틸렌 유연격자와 말단 알콕시기의 길이에 크게 의존하였다. 중합체 I과 계열 III 화합물은 녹는점과 등방성액체화 전이온도에서 짝수-홀수 효과를 보여 주었으나 계열 II와 IV 화합물은 등방성액체화 전이온도에서만 짝수-홀수 효과를 나타내었다. 편광현미경을 통하여 이들의 광학구조를 관찰하였을 때 네마틱과 스멕틱 액정상을 형성하였다.

• Archives of Pharmacal Research
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• 제27권3호
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• pp.273-277
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• 2004

In previous studies for the development of new anticonvulsants, we found that N-Cbz-$\alpha$-amino-N-alkylsuccinimides exhibited significant anticonvulsant activities in the Maximal electroshock seizure (MES) and Pentylenetetrazole induced seizure (PTZ) tests, and also their anticonvulsant activities were dependent on the N-alkyl substituents existent in their structures. Based on these estimations, N-Cbz-$\alpha$-amino-N-hydroxysuccinimide and various N-Cbz-$\alpha$-amino-N-alkoxysuccinimides were prepared in order to develop more active anticonvulsants and to examine the effects of N-hydoxy or N-alkoxy groups on their anticonvulsant activities. The (R)-or (S)-N-Cbz-$\alpha$-amino-N-hydroxysuccinimide and N-Cbz-$\alpha$-amino-N-alkoxysuccinimides were prepared from the corresponding (R)-or (S)-N-Cbz-aspartic acid through the known synthetic procedures. Their anticonvulsant activities in the MES and PTZ test were evaluated. All of these compounds except 3a showed significant anticonvulsant activities against the PTZ test, but these compounds were not active in the MES test. The most active compound in the PTZ test was (R)-N-Cbz-$\alpha$-amino-N-benzyloxysuccinimide (ED$_{50}$=62.5 mg/kg). In addition, the anti-convulsant activities of these compounds were dependent on their N-substited groups. The order of anticonvulsant activity against the PTZ test, as judged from the ED50 values for (R) series was N-benzyloxy > N-hydroxy > N-isopropoxy > N-methoxy > N-ethoxy; for the (S) series N-ethoxy > N-benzyloxy > N-methoxy > N-isopropoxy.y.

• 공업화학
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• 제28권6호
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• pp.626-631
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• 2017

투명 플라스틱 소재를 광학용으로 적용하기 위해서는 표면경도 및 내열성과 같은 물성의 개선이 필요하다. 본 연구에서는 이러한 물성의 개선을 위하여 자외선 경화형 유기/무기 하이브리드를 합성하였다. 유기소재 안에 무기 성분이 균일하게 최적상태로 분산되도록 하기 위하여 졸-겔 반응을 기초로 하여 동시에 반응이 진행되도록 하였다. 이러한 졸-겔 반응과 빠른 자외선 경화반응을 적절히 조합하여 우레탄 아크릴레이트 유기소재 안에 무기 성분의 분산성이 향상되도록 하여 투명성이 우수한 코팅층을 형성시킬 수 있었다. 자외선 경화형 유기/무기 하이브리드의 경화도와 코팅 물성을 변화시키기 위하여 다양한 종류의 알콕시 실란을 사용하였다. 이러한 자외선 경화형 유기/무기 하이브리드 코팅에서의 무기 성분의 함량에 따라 표면 경도와 내열성을 조절할 수 있었다.

• Archives of Pharmacal Research
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• 제27권2호
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• pp.151-155
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• 2004

In our previous studies for the development of new anticonvulsant of broad spectrum, we found that N-cbz-$\alpha$-aminoglutarimides showed significant anticonvulsant activities of broad spectrum enough to be recommended for the new anticonvulsants and their anticonvulsant activities were dependent on their imide substituent groups. Based on these results, various N-cbz--$\alpha$-amino-N-alkoxyglutarimides, where the imide N-H was substituted with the hydroxy and alkoxy group, were prepared and evaluated for their anticonvulsant activities using the Maximal electroshock seizure (MES) and Pentylenetetrazole induced seizure (PTZ) tests and also the rotorod test. A series of (R) or (S)-N-cbz--$\alpha$-amino-N-alkoxyglutarimides could be prepared from the corresponding (R) or (S)-N-cbz-glutamic acid following the usual synthetic procedure. Among them, (R)-N-cbz--$\alpha$-amino-N-hydroxyglutarimide ($ED_{50}$=86.25 mg/kg) was most active in the MES test. In the case of the PTZ test, (R)-N-cbz--$\alpha$-amino-N-benzyloxyglutarimide ($ED_{50}$= 62.5 mg/kg) was most active. Among the tested compounds, 2a-c, 3a, and 3b showed anticonvulsant activities in the MES and PTZ test. All of the tested compounds, except 2f and 3f, showed significant anticonvulsant activities in the MES or PTZ test. In addition, the neurotoxicities of these compounds were comparable to other anticonvulsant drugs.

• Bulletin of the Korean Chemical Society
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• 제35권10호
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• pp.3052-3058
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• 2014

In this article, we have designed and synthesized a novel donor-${\pi}$-acceptor (D-${\pi}$-A) type porphyrin-based sensitizer (denoted UI-5), in which a carboxyl anchoring group and a 9,9-dimethyl fluorene were introduced at the meso-positions of porphyrin ring via phenylethynyl and ethynyl bridging units, respectively. Long alkoxy chains in ortho-positions of the phenyls were supposed to reduce the degree of dye aggregation, which tends to affect electron injection yield in a photovoltaic cell. The cyclic voltammetry was employed to determine the band gap of UI-5 to be 1.41 eV based on the HOMO and LUMO energy levels, which were estimated by the onset oxidation and reduction potentials. The incident monochromatic photon-to-current conversion efficiency of the UI-5 DSSC assembled with double-layer (20 nm-sized $TiO_2$/400 nm-sized $TiO_2$) film electrodes appeared lower upon overall ranges of the excitation wavelengths, but exhibited a higher value over the NIR ranges (${\lambda}$ = 650-700 nm) compared to the common reference sensitizer N719. The UI-5-sensitized cell yielded a relatively poor device performance with an overall conversion efficiency of 0.74% with a short circuit photocurrent density of $3.05mA/cm^2$, an open circuit voltage of 0.54 mV and a fill factor of 0.44 under the standard global air mass (AM 1.5) solar conditions. However, our report about the synthesis and the photovoltaic characteristics of a porphyrin-based sensitizer in a D-${\pi}$-A structure demonstrated a significant complex relationship between the sensitizer structure and the cell performance.

• 약학회지
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• 제52권5호
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• pp.376-383
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• 2008

Chungkookjang (CKJ) is a fermented soybean product and one of favorite traditional foods in Korea. In this study, the alcoholic extract from Korean fermented soybean (CKJ) and its one of major flavonoids, genistein were evaluated for their protective effect against B(a)P induced cytotoxicity and DNA damage in HepG2 cells. CKJ extract and genistein decreased B(a)P-induced cell cytotoxicity. CKJ extract inhibited DNA single strand breaks evaluated by single cell gel electrophoresis. From RT-PCR study, it was revealed that CKJ extract decrease DNA damage induced in HepG2 cells expressing CYP1A1 and 1A2 by B(a)P. The metabolizing activities of CYP1A1 and CYP1A2, as measured by the 7-alkoxy resorufin O-deethylation (AROD) assay, showed that CKJ extract and genistein inhibited CYP1A1 and CYP1A2 activities. Genistein may contribute to these biological effects of CKJ extract at least in part. All these results indicate that CKJ extract and genistein may be useful for protection against B(a)P-induced cytotoxicity and DNA damage. Therefore, the alcoholic extract of Korean fermented soybean (CKJ) is suggested to be promising functional food which can prevent the cellular genotoxicity of dietary and lifestyle related carcinogens.

• Elastomers and Composites
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• 제55권1호
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• pp.51-58
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• 2020

In this study, the thermal oxidation of raw natural rubber (NR) was investigated under controlled conditions by optical image and fourier transform infrared (FT-IR) analysis. The thermal oxidation was performed on a transparent thin film of raw NR coated on a KBr window in a dark chamber at 80℃ under low humidity conditions to completely exclude moisture and restrict light oxidation. Images of the thin film of raw NR were obtained before and after thermal oxidation. FT-IR absorption spectra were measured in the transmission mode at different thermal exposure times. The thermal oxidation of NR was examined by the changes in the absorption peaks at 3449, 1736, 1447, 1377, 1242, 1072, and 833 cm^-1, which corresponded to a hydroxyl group (-OH), a carbonyl group (-C=O) from an aldehyde and a ketone, a methylene group (-CH₂-), a methyl group (-CH₃), a carbon-oxygen single bond (-C-O) from an epoxide, a carbon-oxygen bond (-C-O) from an ether, an alcohol, a peroxide, or a cyclic peroxide, and a cis-methine group (cis-CCH₃=CH-), respectively. In the initial stage of thermal oxidation, two different types of free radicals were produced quickly and randomly by the homolytic cleavage of a double bond and allylic hydrogen abstraction. Aldehydes and ketones were formed from chain scissions of the double bonds and alcohols were produced from allylic hydrogen abstraction at the methylene or methyl groups. Two reactions seemed to proceed competitively with each other. At a later stage, oxidative crosslinks seemed to dominate through the combination of free radicals such as an allyl radical (CH=CHCH₂·), alkoxy radical (RO·), and peroxy radical (ROO·) and the reaction of a hydroperoxide (-ROOH) with a double bond. The image obtained after thermal oxidation showed hardening without cracks. Based on these observations, a plausible two-step mechanism was suggested for chain hardening caused by the thermal oxidation.

• 대한화학회지
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• 제17권4호
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• pp.275-285
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• 1973

유기화합물의 선택환원에 필요한 자료를 얻기 위하여 수소화붕소나트륨과 염화알루미늄의 3:1 혼합물의 테트라히드로푸란 용액에서의 환원성을 규명하였다. 49개의 대표적 유기화합물을 골라 이시약과 실온에서 작용하여 대략의 반응속도와 정량관계를 알아보았다. 테트라히드로푸란 용액에서 염화알루미늄 1몰에 수소화붕소나트륨 3몰을 가하면 현탁용액이 생기는데 수소화붕소나트륨 보다는 훨씬 환원성이 강하다. 알데히드와 케톤은 한시간 이내에 빨리 환원되고 아실유도체는 서서히 그러나 카르복시산은 매우 느리게 환원되었다. 에스테르, 락톤, 에폭시드는 수소화붕소나트륨이나 보란보다 훨씬 빨리 환원되었다. 삼차 아미드는 서서히 환원되었으나 일차 아미드는 수소는 발생하지만 환원은 거의 일어나지 않았다. 벤조니트릴은 30분에 환원이 완결되었으나 카프로니트릴은 느리게 환원되었다. 니트로화합물, 이황화물, 술폰등은 이 시약과 반응하지 않으나 아조, 아족시, 옥심기는 서서히 반응하고 이소시안산페닐은 도중단계까지만 환원되었다 올레핀은 쉽게 수소화붕소화 반응을 하였다.