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고리형 α, α-이치환-α -아미노산을 도입한 펩타이드의 합성과 2차 구조 분석
이경,임세진 동덕여자대학교 종합약학연구소 2005 동덕약학연구지 Vol.9 No.-
α-Helix is a typical secondary structure found in many bioactive proteins, peptides, and fibrous polymers. α,α-Disubstituted amino acid, a special amino acid having two alkyl groups at α-carbon, has a restricted structure. Therefore, once incorporated into a peptide it can modify the degree of freedom and promote the formation of α-helix, also it can stabilize α-helical structure. Previously 1-phenyl-piperidine-4-carboxylic acid(Ppi), a cyclic six-membered α,α-disubstituted α-amino acids had been synthesized in our laboratory. The object of this research was to investigate the tendency of Ppi to promote the formation of peptide secondary structure. We selected two pentapeptides, Boc-Val-ΔPhe-Ala-Leu-Gly-OMe and Boc-Leu-Dbg-Val-Ala-Leu_OMe, which were reported to form α-helices as the control and replaced special amino acids (ΔPhe and Dbg) with Ppi. We synthesized two pentapeptides: Boc-Val-Ppi-Ala-l,eu-Gly-OMe [4] and Boc-Leu-Ppi-Val-Ala-Leu-OMe [8] by using solution-Phase peptide synthesis strategy. Their secondary structures were measured by CD spectroscopy analysis. The control peptide Boc-Val-ΔPhe-Ala-Leu-Gly-OMe made a (-) band near 202 nm and 227~228nm, indicating the formation of α-helical structure. Boc-Val-Ppi-Ala-l,eu-Gly-OMe [4] made a (-) band near 205 nm and Boc-Leu-Ppi-Val-Ala-Leu-OMe [8] made a (-) band near 200~205nm. This means these peptides form a random coil structure. In conclusion, Ppi in two pentapeptides (4,8) did not promote the formation of peptide secondary structure.
수분에 의한 페로브스카이트 박막의 분해 및 δ-phase 결정 형성을 억제하기 위한 표면 처리 기술
손경난(Kyung Nan Son),Syed Dildar Haider Naqvi,정인영(In Young Jeong),안세진(SeJin Ahn),장효식(Hyo Sik Chang) 한국태양광발전학회 2021 Current Photovoltaic Research Vol.9 No.2
Perovskite solar cells (PSCs) are currently attracting attention as a promising source of photovoltaic power generation for their rapid increase in efficiency within a short research period. However, the 2-step deposition method, which has been considered as a proper film fabrication route in commercialization point of view of PSC, requires a complicated control of environment to achieve high efficiency because each step of the process are affected by humidity in different manner. It is clearly a large hurdle for this technic to be transferred to industrialization. In this study, we developed a simple surface treatment by which high quality perovskite films can be fabricated through 2-step deposition method in a relatively wide humidity range without complicated humidity control at each step.
이중유화법을 통하여 BSA 수용액을 PLGA 마이크로캡슐 입자에 봉입하는 과정에서의 공정변수의 영향
권세진(Sejin Kwon),구자경(Ja-Kyung Koo) 한국산학기술학회 2018 한국산학기술학회논문지 Vol.19 No.6
이중유화법을 통하여 BSA 수용액을 봉입하는 PLGA 마이크로캡슐 입자를 제조하였다. 마이크로캡슐 입자 외부의 수용액 상에서는 입자 표면의 경화를 위하여 유화제를 금속염으로 대체하였다. 제조한 마이크로캡슐 입자에 대하여서 모폴로지, 입자직경 BSA 봉입효율 및 in-vitro 방출실험을 수행하였다. 전자현미경(SEM) 촬영을 통하여 마이크로캡슐 입자는 l-7㎛ 유화액 내 내부 수용액 대비 고분자 용액의 부피 비 그리고 입자 외부 수용액에서의 금속염의 농도에 직접적인 영향을 받았다. 또한 이러한 요소는 단백질 봉입효율과 in-vitro 방출에도 일부 영향을 미쳤다. 본 실험에서 제조한 마이크로캡슐 입자는 in-vitro 방출 실험에서 초기에 높은 유속의 방출 현상을 보였다. 그렇지만 본 연구에서 제조한 마이크로캡슐 입자는 다른 연구의 결과에 비해 긴 기간 동안의 방출을 보였다. 이상의 결과를 통해 2가의 금속염이 마이크로캡슐 입자의 제조에서 유화제를 대체할 수 있는 좋은 방편이 될 수 있다는 결론을 내릴 수 있었다. PLGA microcapsule particles encapsulating BSA aqueous solutions were prepared using a water-in-oil-in-water emulsion method. The morphology, particle size, BSA encapsulating efficiency, and in-vitro release test were also studied using the microcapsule particles. In the outer aqueous phase, an emulsifier, e.g., PVA, was replaced with metal salts for surface solidification. Scanning electron microscopy (SEM) showed that the microcapsule particles had smooth surfaces and were between 1㎛ and 7㎛ in size. The micro capsule particle morphology was affected directly by the ratio between the polymer solution and inner aqueous solution, and composition of the outer aqueous solution. The factors also partially affected the BSA encapsulation efficiencies and in-vitro release rates. All the micro capsule particles showed an initial burst release through the in-vitro release test. On the other hand, the particles also showed a relatively long release period. Metal salts could be good choices to replace the emulsifier to solidify the microcapsule particle surfaces.
Mechanism of Electrospinning for Poly(amic acid)/Polyacrylonitrile Fiber Fabrication
Choi, Sejin,Kim, Hye Ri,Jeong, Yu Kyung,Bang, Ju Yup,Kim, Han Seong Taylor & Francis 2018 Journal of Macromolecular Science. Part B Vol.57 No.3
<P>A poly(amic acid) (PAA) solution in xylene was prepared for electrospinning in order to fabricate fibers. However, jet breaking occurred at the point of the occurrence of whipping instability, resulting in forming micro-particles. This was an exceptional jet behavior compared with the general electro-spraying process that occurs directly from the surface of the polymer droplet. It is important to understand the mechanism of electrospinning and the instability of PAA in order to form fibers for mat deposition. Thus, the behavior of the jet breaking was clearly observed by a high-speed camera and the dynamic behavior of the jet was explored by an image analysis technique. Furthermore, polyacrylonitrile (PAN) was added to the PAA/xylene solution with various concentrations to change the elongation viscosity. Uniform diameter fibers were obtained by increasing the content of PAN to the level that the drag force between the polymer chains increased enough to overcome the drawing force. As a result the optimum content ratio of the PAA/PAN mixed solution to obtain the desired fiber spinning and deposition was determined as being 5:5.</P>
Effectiveness of full spectrum light soaking on solar cell degradation analysis
박상현,SeJin Ahn,곽지혜,Keeshik Shin,Seoung Kyu Ahn,Kyung Hoon Yoon,Yunae Cho,김동욱,Jae Ho Yun 한국물리학회 2013 Current Applied Physics Vol.13 No.8
This study examined the effect of UV-spectrum light soaking on solar cell degradation tests. An indoor light soaking test was evaluated over three different spectral ranges: “UV only”, “UV blocked” and “Full spectrum”. a-Si:H and poly-crystalline silicon solar cell technologies were studied by light soaking tests with the same optical filter configurations. The IeV measurement results demonstrated that “UV only” irradiated solar cells exhibited the smallest output power degradation, which was only half of a percent variation compared with the full spectrum light soaking case. Using a filter that excluded the effect of the UV spectral range on light soaking, the “UV blocked” case also exhibited a significant output power degradation of the solar cells. A comparative analysis of the solar cell response, based on the IeV characteristics and the diode ideality factor under these different light soaking spectra, demonstrated the importance of the full spectrum light soaking test in the evaluation of the long-term performance of solar cells.
Chanwoo Kim,Geunyoung Yeom,Sejin Kyung,Yonghyuk Lee 한국물리학회 2005 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.46 No.4
(DBD)-type atmospheric-pressure plasma-enhanced chemical vapor deposition (AP-PECVD) system at a low temperature of 400 C, and their growth characteristics were investigated. The CNTs grown using He (6 slm)/C2H2 (90 sccm) AP-PECVD with additive gases (NH3, N2) for 5 minutes at 400C after a pretreatment were multi-layer CNTs with diameter of 20 – 50 nm and uniform lengths of 1.5 – 2 μm. FT-Raman spectroscopy showed that the grown CNTs were multi-wall CNTs with a D-band/G-band intensity ratio of 0.9. Transmission electron microscopy of the AP-PECVDgrown CNTs showed that the CNT had a 30-nm outer diameter and a 7-nm hollow inner diameter with a Ni particle on the top of the tube.