• Bulletin of the Korean Chemical Society
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• 제33권8호
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• pp.2523-2528
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• 2012

Green phosphors $(Zn_{1-a-b}M_aM^{\prime}_b)_xGa_yS_{x+3y/2}:Eu^{2+}$ (M, M' = alkali earth ions) with x = 2 and y = 2-5 were prepared, starting from ZnO, MgO, $SrCO_3$, $Ga_2O_3$, $Eu_2O_3$, and S with a flux $NH_4F$ using a conventional solidstate reaction. A phosphor with the composition of $(Zn_{0.6}Sr_{0.3}Mg_{0.1})_2Ga_2S_5:Eu^{2+}$ produced the strongest luminescence at a 460-nm excitation. The observed XRD patterns indicated that the optimized phosphor consisted of two components: zinc thiogallate and zinc sulfide. The characteristic green luminescence of the $ZnS:Eu^{2+}$ component on excitation at 460 nm was attributed to the donor-acceptor ($D_{ZnGa_2S_4}-A_{ZnS}$) recombination in the hybrid boundary. The optimized green phosphor converted 17.9% of the absorbed blue light into luminescence. For the fabrication of light-emitting diode (LED), the optimized phosphor was coated with MgO using magnesium nitrate to overcome their weakness against moisture. The MgO-coated green phosphor was fabricated with a blue GaN LED, and the chromaticity index of the phosphor-cast LED (pc-LED) was investigated as a function of the wt % of the optimized phosphor. White LEDs were fabricated by pasting the optimized green (G) and the red (R) phosphors, and the commercial yellow (Y) phosphor on the blue chips. The three-band pc-WLED resulted in improved color rendering index (CRI) and corrected color temperature (CCT), compared with those of the two-band pc-WLED.

• 한국생물공학회:학술대회논문집
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• 한국생물공학회 2000년도 추계학술발표대회 및 bio-venture fair
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• pp.579-582
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• 2000

(R,S)-3-amino-n-butanoic acid에 대한 광학분할 능력이 우수한 균주 Alcaligenes denitrificans Y2k-2를 토양으로부터 분리하였다. 광학분할 반응에 관계하는 효소는 트랜스아미나제로 추정되며, 아민 수용체에 대한 특이성에서 크기가 작을수록 반응성이 높아지는 경향이 있다. pyruvate에 의한 기질저해 현상이 나타나는데, 효율적인 생산 체계를 갖추기 위해서 이 문제를 해결할 필요가 있으며 현재 효소의 정확한 특성을 파악하기 위한 실험을 진행 중이다.

• 한국미생물·생명공학회지
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• 제5권3호
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• pp.141-151
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• 1977

Nocardia sp의 tellurite 및 tellurate 환원효소의 세포내 분포 및 이의 정제법에 대한 실험과 효소 화학약 성질에 대한 연구를 요약하면 다음과 같다. Nocardia sp의 tellurite 및 tellurate 환원효소는 세포질중에 존재하며 T.T.C.의 환원부위와는 세포내에서의 존재양식이 서로 다르다. 세포용성 성분을 균체로부터 조제하여 이것을 재료로 해서 유안여석법, DEAE-Cellulose column chromatography등을 병용함에 따라, tellurite및 tellurate 환원순서의 정제가 가능하다. 이상의 정제효소를 사용하여 이의 낙소 화학적 성질에 대하여 검토한 결과, 수소공여체로는 NADH, NADPH 환원형(methylene blue)의 어느 것이든 작용한다는 것을 알았지마는 아마 생리적 수소공여체는 NADH, NADPH의 양자이든가 또는 이들 양자중에서 어느 하나일 것이다. 한편 이들 수소공여체에 대한 수소수용기는 본 효소에 있어서는 tellurite가 균체의 기질이 되지마는 tellurite 및 tellurate와 화학구조가 유사한 selenite, selenate를 환원하여 각각의 기질화합물중에 함유되어 있는 금속을 석출한다는 것도 알게 되었다.

• Bulletin of the Korean Chemical Society
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• 제35권2호
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• pp.587-596
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• 2014

A new ${\pi}$-stacked donor-acceptor (D-A) system, [Ru(1-([2,2'-bipyridine]-6-yl-methyl)-3-(2-cyclohexa-2',5'-diene-1,4-dionyl)-1H-imidazole)(2,2':6',2"-terpyridine)]$[PF_6]_2$ (ImQ_T), has been synthesized and characterized. Similar to its precedent, [Ru(6-(2-cyclohexa-2',5'-diene-1,4-dione)-2,2':6',2"-terpyridine)(2,2':6',2"-terpyridine)]$[PF_6]_2$ (TQ_T), this system has a cofacial alignment of terpyridine (tpy) ligand and quinonyl (Q) group, which facilitates an electron transfer through ${\pi}$-stacked manifold. Despite the presence of lowest-energy charge transfer transition from the Ru-based-HOMO-to-Q-based-LUMO (MQCT) predicted by theoretical calculations by using time-dependent density functional theory (TD-DFT), the experimental steady-state absorption spectrum does not exhibit such a band. The selective excitation to the Ru-based occupied orbitals-to-tpy-based virtual orbital MLCT state was thus possible, from which charge separation (CS) reaction occurred. The photo-induced CS and thermal charge recombination (CR) reactions were probed by using ultrafast visible-pump/mid-IR-probe (TrIR) spectroscopic method. Analysis of decay kinetics of Q and $Q^-$ state CO stretching modes as well as aromatic C=C stretching mode of tpy ligand gave time constants of <1 ps for CS, 1-3 ps for CR, and 10-20 ps for vibrational cooling processes. The electron transfer pathway was revealed to be Ru-tpy-Q rather than Ru-bpy-imidazol-Q.

• 약학회지
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• 제42권3호
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• pp.257-264
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• 1998

5-Methylthebaine was obtained by treating thebaine with n-butyllithium and methylfluorosulfonate. Hetero Diels-Alder reaction of thebaine and 5-methylthebaine with trifluoroacet aldehyde afforded 14-${\beta}$-(triflu-oro-2-hydroxyethyl)codeine (2) and 14-${\beta}$-(trifluoro-2-hydroxyethyl)-5-methylcodeinone (9). 6-${\alpha}$-OH compound (4) was obtained by employing $CeCl_2$ and $NaBH_4$. After synthesized a derivative substituted for 3-OH (5), using boron tribromied, We synthesized a new derivative that make double bond in C-7, C-8 into epoxode (6), (10). Through inspecting an influence on structure-activity and analgetic action, we are going to examine which opiold acceptor has a selectivity.

• 한국고분자학회:학술대회논문집
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• 한국고분자학회 2006년도 IUPAC International Symposium on Advanced Polymers for Emerging Technologies
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• pp.165-165
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• 2006

We prepared nonlinear optical (NLO) polymers possessing thermal and temporal stability, which were based on the polyimides appended with NLO chromophores. NLO chromophores with a terminal hydroxyl group have been synthesized by coupling between aminobenzene or julolidine donor and phenylene bridge, and then subsequent coupling between the resulting product and tricyanofuran acceptor. The chromophores were chemically bonded to the polyimides backbone through Mitsunobu reaction. The NLO polymers showed $160-170^{\circ}C$ of Tgs and were thermally stable up to $200^{\circ}C$. We obtained optical quality films by spincoating and evaluated their electro-optical properties and temporal stability.

• 한국재료학회지
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• 제12권6호
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• pp.476-481
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• 2002

In this work, we report on the synthesis of the GaN powders from gallium oxide hydroxide (GaOOH) powders and on the structural and optical properties of them. Simple heat treatment of GaOOH in the flow of $NH_3$ gas leads to the formation of submicron hexagonal GaN powders even at the low reaction temperature of $800^{\circ}C$. XRD measurements show that the powders obtained are the single phase GaN. EDS, FTIR, and PL measurements indicate the oxygen-associated characteristics. It is shown from the low temperature PL measurement on GaN powders synthesized at $1000^{\circ}C$ that the shallow donor-acceptor recombination induced emission is more intense than the near band-edge excitonic emission.

• 한국추진공학회:학술대회논문집
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• 한국추진공학회 1998년도 제11회 학술강연회논문집
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• pp.23-23
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• 1998

Michael Reaction을 이용하여 상업적으로 이용 가능한 APS(3-aminopropyltrime thoxysilane)과 AEAPS(N-[3-(trimethoxysilyl)propy1] ethylenediamine)을 다수의 Michael acceptor(ethyl acrylate, acrylonitrile, acrylamide, 2-cyanoethyl acrylate, 2-hydroxyethyl acrylate 그리고 3-(trimethoxysilyl)propylmethacrylate)와 반응시켜 10종류의 aminosilane ([3-｛N-2-carboethoxyethyl)aminopropyl]triethoxysilane, [3-(N-2-cyanoethyl)aminopropyl] triethoxysilane, [3-(N-di-2-carboethoxyethyl) aminopropyl]triethoxysilane, [3-(N-di-2-cyanoethyl)aminopropyl]triethoxysilane, [3-(N-2-cyanoethoxypropionyl)aminopropyl] triethoxysilane, [3-(N-di-2-cyanoethoxypropionyl)aminopropyl] triethoxysilane, [3-(N-di-2-hydroxyethoxypropionyl) aminopropyl]-triethoxysilane, [3-(N-2-amidoethyl aminopropyl]triethoxysilane, ｛3-[N-(N-di-2-cyanoethyl)ethyl]aminopropyl)triethoxysilane, ｛3-[N-(3-trimethoxy-silylpropyl)-2-methylpropionyl]aminopropyl)triethoxysilane 등을 35-70% 수율로 제조하였으며, 이들의 구조는 $^1$H-NMR과 FT-IR spectroscopy를 이용하여 확인하였다.

• Bulletin of the Korean Chemical Society
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• 제28권12호
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• pp.2369-2376
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• 2007

N2O has been found from experimental and theoretical considerations to bind on-top to the Pd(110) surface in a tilted end-on fashion via its terminal N atom. We use a frontier orbital description of the bonding interactions in the Pd-N2O system to obtain molecular insight into the catalytic mechanism of the activation of N2O by the Pd(110) surface giving rise to the formation of N2 and O on the surface. For the tilted end-on N2O binding mode, the LUMO 3π of N2O has good overlap with the Pd dσ and dπ orbitals which can serve as the electron donors. The donor-acceptor orbital overlap is favorable for electron transfer from Pd to N2O and is expected to dominate the surface reaction pathway of N2O decomposition.

• 한국세라믹학회지
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• 제44권12호
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• pp.683-689
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• 2007

Grain-boundary conduction in the fluorite-structure solid oxide electrolytes such as acceptor-doped zirconia and ceria were reviewed. The siliceous impurity, even several hundreds ppm, affects the ionic conduction across grain boundary to a great extent. Various approaches to improve grain-boundary conduction in fluorite-structure oxide electrolytes have been investigated, which include (1) the scavenging of siliceous phase by the reaction with second phase, (2) the gathering of intergranular siliceous phase into a discrete configuration and (3) the dewetting of intergranular liquid phase by post-sintering heat treatment.