• The Korean Journal of Physiology and Pharmacology
• /
• 제12권6호
• /
• pp.323-330
• /
• 2008

The properties of voltage dependent $Ca^{2+}$ current (VDCC) were investigated in interstitial cells of Cajal (ICC) distributed in the myenteric layer (ICC-MY) of guinea-pig antrum. In tissue, ICC-MY showed c-Kit positive reactions and produced driving potentials with the amplitude and frequency of about 62 mV and 2 times $min^{-1}$ respectively, in the presence of $1{\mu}M$ nifedipine. Single ICC-MY isolated by enzyme treatment also showed c-Kit immunohistochemical reactivity. These cells were also identified by generation of spontaneous inward current under $K^+$ -rich pipette solution. The voltage clamp experiments revealed the amplitude of - 329 pA inward current at irregular frequency. With $Cs^+$-rich pipette solution at $V_h=-80\;mV$, ICC-MY produced voltage-dependent inward currents (VDIC), and nifedipine ($1{\mu}M$) blocked VDIC. Therefore, we successfully isolated c-Kit positive single ICC from guinea-pig stomach, and found that ICC-MY potently produced dihydropiridine sensitive L-type voltage-dependent $Ca^{2+}$ currents ($VDCC_L$).

• Biomolecules & Therapeutics
• /
• 제24권1호
• /
• pp.85-93
• /
• 2016

We already reported that genetically engineered resveratrol-enriched rice (RR) showed to down-regulate skin melanogenesis. To be developed to increase the bioactivity of RR using calli from plants, RR was adopted for mass production using plant tissue culture technologies. In addition, high-pressure homogenization (HPH) was used to increase the biocompatibility and penetration of the calli from RR into the skin. We aimed to develop anti-melanogenic agents incorporating calli of RR (cRR) and nanoparticles by high-pressure homogenization, examining the synergistic effects on the inhibition of UVB-induced hyperpigmentation. Depigmentation was observed following topical application of micro-cRR, nano-calli of normal rice (cNR), and nano-cRR to ultraviolet B (UVB)-stimulated hyperpigmented guinea pig dorsal skin. Colorimetric analysis, tyrosinase immunostaining, and Fontana-Masson staining for UVB-promoted melanin were performed. Nano-cRR inhibited changes in the melanin color index caused by UVB-promoted hyperpigmentation, and demonstrated stronger anti-melanogenic potential than micro-cRR. In epidermal skin, nano-cRR repressed UVB-promoted melanin granules, thereby suppressing hyperpigmentation. The UVB-enhanced, highly expressed tyrosinase in the basal layer of the epidermis was inhibited by nano-cRR more prominently than by micro-cRR and nano-cNR. The anti-melanogenic potency of nano-cRR also depended on pH and particle size. Nano-cRR shows promising potential to regulate skin pigmentation following UVB exposure.

• 센서학회지
• /
• 제10권2호
• /
• pp.118-124
• /
• 2001

입자들이 용액에 녹아있을 때 pH에 따라서 다른 zeta-potential을 가지게 되며, 이것은 입자의 분산상태에 영향을 주게 된다. NO 센서에서 $WO_3$ 입자의 크기는 감도에 큰 영향을 끼치므로 Sol-Coprecipitation법에 의한 $WO_3$ 센서 제조 시에 $WO_3$ precursor 상태에서의 pH의 영향을 알아보았다. 먼저 $WO_3$ precursor의 전기적 포텐셜을 측정하여 pH가 2에서 7로 변함에 따라 mobility가 증가하여 7일 때에 가장 큰 분산도를 가진 것을 알 수 있었고, 이는 powder 제조 후 입도 분석, 감지막의 XRD peak, 표면사진으로부터 확인 할 수 있었다. 결과적으로 감도 특성에도 영향을 끼쳐 pH=7에서 제조한 센서가 다른 pH에서 제조한 센서보다 감도가 우수한 것으로 나타났다.

• 생명과학회지
• /
• 제21권11호
• /
• pp.1631-1635
• /
• 2011

재조합 아밀로수크라아제의 폴리페놀 배당체를 합성하는 능력을 검사하였다. 이 효소의 효소작용 특성에 근거하여 설탕을 기질로 사용하였으며 21 종류의 각기 다른 폴리페놀 화합물들이 수용체로 사용되었다. 당 전이 반응은 사용한 폴리페놀에 따라 하나 또는 두 개의 주요 폴리페놀 배당체를 합성하였다. 합성된 폴리페놀 배당체들은 박막 크로마토그래피법을 이용하여 확인되었고, 새로이 합성된 배당체의 구조는 당 전이 작용 특성에 근거하여 예측되었다. 수용체로 가능한 폴리페놀의 구조적 특징들이 평가되었으며, 이러한 결과는 Deinococcus geothermalis 유래 아밀로수크라아제가 식품, 화장품, 및 제약산업에서 높은 잠재성을 갖는 폴리페놀 배당체의 효소적 합성에 매우 효율적인 촉매로 활용될 수 있다는 것을 보여준다.

• 한국재료학회지
• /
• 제23권11호
• /
• pp.638-642
• /
• 2013

Chalcopyrite $CuInSe_2$(CIS) is considered to be an effective light-absorbing material for thin film photovoltaic solar cells. CIS thin films have been electrodeposited onto Mo coated and ITO glass substrates in potentiostatic mode at room temperature. The deposition mechanism of CIS thin films has been studied using the cyclic voltammetry (CV) technique. A cyclic voltammetric study was performed in unitary Cu, In, and Se systems, binary Cu-Se and In-Se systems, and a ternary Cu-In-Se system. The reduction peaks of the ITO substrate were examined in separate $Cu^{2+}$, $In^{3+}$, and $Se^{4+}$ solutions. Electrodeposition experiments were conducted with varying deposition potentials and electrolyte bath conditions. The morphological and compositional properties of the CIS thin films were examined by field emission scanning electron microscopy (FE-SEM) and energy dispersive spectroscopy (EDS). The surface morphology of as-deposited CIS films exhibits spherical and large-sized clusters. The deposition potential has a significant effect on the film morphology and/or grain size, such that the structure tended to grow according to the increase of the deposition potential. A CIS layer deposited at -0.6 V nearly approached the stoichiometric ratio of $CuIn_{0.8}Se_{1.8}$. The growth potential plays an important role in controlling the stoichiometry of CIS films.

• Bulletin of the Korean Chemical Society
• /
• 제30권10호
• /
• pp.2371-2376
• /
• 2009

Three phenoxazine-based conjugated polymers, namely, the aryl substituted phenoxazine homopolymer (P1) as well as the dimeric phenoxazine-fluorene (P2) and phenoxazine-bithiophene (P3) copolymers, were synthesized via the Ni(0) mediated Yamamoto reaction and the palladium-catalyzed Suzuki coupling reaction. The weight-averaged molecular weights ($M_w$) of P1, P2, and P3 were found to be 27,000, 22,000, and 15,000, respectively, and their polydispersity indices were 3.6, 1.8, and 2.1. All the polymers were soluble in common organic solvents such as chloroform, toluene, and so on. The UV-visible absorption maxima for P1, P2, and P3 in the film state were located at 421, 415 and 426 nm, respectively, and the ionization potentials of the polymers ranged between 4.90 and 5.12 eV. All the studied phenoxazine-based polymers exhibited amorphous behavior, as confirmed by X-ray diffraction (XRD) and atomic force microscopy (AFM) studies. Thin film transistors were fabricated using the top-contact geometry. P1 showed much better thin-film-transistor performance than P2 or P3: A thin film of P1 gave a saturation mobility of 0.81 ${\times}\;10^{-3}\;cm^2V^{-1}s^{-1}$ and an on/off ratio of about $10^2$.

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

• 청정기술
• /
• 제12권4호
• /
• pp.211-216
• /
• 2006

단면이 직사각형 형태를 갖는 마이크로채널에서 이론적인 퍼텐셜의 분포변화를 제타퍼텐셜과 수력학적 지름을 변수로 조사하였다. 그리고 종/횡(Height-Width) 비를 1, 1/2, 1/3로 변화시켜서 형태의 변화에 따른 퍼텐셜의 분포변화를 조사하였다. 이를 위하여 Comsol 사의 FEMLAB 3.0을 이용하여 전산 무사를 실시하였다. 그 결과 단면의 수력학적 지름이 감소함에 따라서 높이방향 표면이 퍼텐셜 분포에 미치는 영향이 일정한 영역까지 나타났다. 또한 단면의 중앙을 지나는 가상의 선상에서 퍼텐셜 값은 제타퍼텐셜에 정비례하여 증가하였으며, 퍼텐셜 값은 단면의 종/횡 비가 증가함에 따라서 그 기울기가 증가하였다. 그렇지만 전체적으로 보았을 때, 단면의 종/횡 비가 감소함에 따라서 전기이중층이 표면방향으로 압축되는 형태를 나타내었으며, 이는 제타퍼텐셜의 증가를 가져올 것으로 사료된다.

• Bulletin of the Korean Chemical Society
• /
• 제25권12호
• /
• pp.1822-1828
• /
• 2004

Electrochemical, in situ electrochemical scanning tunneling microscope (EC-STM), and attenuated total reflectance-FTIR (ATR-FTIR) spectroscopic methods were employed to investigate the preparation of atomically flat Si(111)-H surface in ammonium fluoride solutions. Electrochemical properties of atomically flat Si(111)-H surface were characterized by anodic oxidation and cathodic hydrogen evolution with the open circuit potential (OCP) of ca. -0.4 V in concentrated ammonium fluoride solutions. As soon as the natural oxide-covered Si(111) electrode was immersed in fluoride solutions, OCP quickly shifted to near -1 V, which was more negative than the flat band potential of silicon surface, indicating that the surface silicon oxide had to be dissolved into the solution. OCP changed to become less negative as the oxide layer was being removed from the silicon surface. In situ EC-STM data showed that the surface was changed from the initial oxidecovered silicon to atomically rough hydrogen-terminated surface and then to atomically flat hydrogenterminated surface as the OCP moved toward less negative potentials. The atomically flat Si(111)-H structure was confirmed by in situ EC-STM and ATR-FTIR data. The dependence of atomically flat Si(111)-H terrace on mis-cut angle was investigated by STM, and the results agreed with those anticipated by calculation. Further, the stability of Si(111)-H was checked by STM in ambient laboratory conditions.

• 한국진공학회지
• /
• 제19권2호
• /
• pp.105-113
• /
• 2010

일차원 나노튜브는 구조는 높은 비표면적, 내부의 빈 공간 및 특유의 물리적 특징을 제공한다. 1차원 산화물 나노튜브 구조물의 합성 방법에 따라 나누어 정리하여 논의하였다. 나노 기판을 이용한 나노튜브 합성은 고른 물리적 구조를 가지는 나노튜브를 대량으로 합성하는데 있어서 이상적인 방법으로서 기판의 형태를 상대적으로 용의하게 조절함으로써 1차원 나노튜브 구조물의 특성을 극대화하였다. 극대화된 특성을 이용한 여러 응용 분야에 대한 연구를 정리하여 제시하였다.