• Bulletin of the Korean Chemical Society
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• 제23권1호
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• pp.81-85
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• 2002

A new di-N-cyanoethylated 14-membered tetraaza macrocycle 1,8-bis(2-cyanoethyl)-3,5,7,7,10,12,14,14-octamethyl-1,4,8,11-tetraazacyclotetradecane $(L^2)$ and its nickel(II) complex $[NiL^2(OAc)]^+$ have been prepared. The square-planar complex $[NiL^2](C IO_4)_2$ can be prepared by addition of $HClO_4$ to a hot aqueous solution of $[NiL^2(OAc)]^+$ The Ni-N (tertiary amino group) bond distances $(2.008{\AA})$ of $[NiL^2](C IO_4)_2$ are relatively long, and the complex exhibits a d-d transition band at unusually long wavelength (ca. 515 nm). The complex $[NiL^2](C IO_4)_2$ rapidly reacts with acetate ion or ethylenediamine (en) to produce $[NiL^2(OAc)]^+$ or [Ni(en)_3]^{2+}$, respectively, and is readily decomposed in NaOH (0.01 M) solution. The chemical properties of $[NiL^2]^{2+}$ as well as its synthetic procedure are quite different from those for other related 14-membered tetraaza macrocyclic complexes. Effects of the N-cyanoethyl and C-methyl groups on the properties of $L^2$.

• 상하수도학회지
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• 제31권4호
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• pp.281-287
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• 2017

Mill scale, an iron waste, was used to separate magnetite particles for the adsorption of phosphate from aqueous solution. Mill scale has a layered structure composed of wustite (FeO), magnetite ($Fe_3O_4$), and hematite ($Fe_2O_3$). Because magnetite shows the highest magnetic property among these iron oxides, it can be easily separated from the crushed mill scale particles. Several techniques were employed to characterize the separated particles. Mill scale-derived magnetite particles exhibited a strong uptake affinity to phosphate in a wide pH range of 3-7, with the maximum adsorptive removal of 100%, at the dosage of 1 g/L, pH 3-5. Langmuir isotherm model well described the equilibrium data, exhibiting maximum adsorption capacities for phosphate up to 4.95 and 8.79 mg/g at 298 and 308 K, respectively. From continuous operation of the packed-bed column reactor operated with different EBCT (empty bed contact time) and adsorbent particle size, the breakthrough of phosphate started after 8-22 days of operation. After regeneration of the column reactor with 0.1N NaOH solution, 95-98% of adsorbed phosphate could be detached from the column reactor.

• Bulletin of the Korean Chemical Society
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• 제20권5호
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• pp.535-538
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• 1999

Five coordinated water-soluble iridium(l) complex, IrH(CO)(TPPTS)3 (1) (TPPTS = P(m-C6H4SO3Na)3-xH2O) has been prepared from the reaction of IrCl3·3H2O with TPPTS and HCHO in H2O/EtOH solution. Complex 1 catalyzes the hydration of nitrites (RC ≡ N, R = CH3, CICH2, CH3(CH2)4, Ph) in aqueous solution to give the corresponding amides (RCONH2) at 100℃. The hydration of unsaturated nitrites (R'C ≡ N, R'=CH3CH=CH, CH3OCH=CH, trans-PhCH=CH, CH2=C(CH3)) takes place regioselectively on-C ≡ N group to give unsaturated amides (R'CONH2) leaving the olefinic group intact. The yields of the amides seem to be depending on the electrophilicity of the carbon of nitrile: The more the electron withdrawing ability of the substituents on nitrites, the more amides are obtained. The hydration of dinitriles (NC-R-CN, R=(CH2)4, (CH2)6) with complex 1 initially gives mono-hydration products (NC-R-CONH2) which are slowly hydrated further to give dihydration products (H2NCO-R-CONH2). The hydration of 1,4-dicyanobutane has been found to be somewhat faster than that of 1,6-dicyanohexane.

• 한국염색가공학회지
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• 제29권4호
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• pp.256-267
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• 2017

The purpose of this study was to analyze the functional ingredients of Perilla Frutescens L. Britt extracts and to confirm the possibility of producing PVA nanofibers using extracts. Distilled water, 3% aqueous sodium hydroxide solution and ethanol were used as extraction solvents. The electrospinning was carried out at a PVA concentration of 12%, an applied voltage of 10 kV and a tip to collector distance of 15cm. The contents of volatile substances, essential oils, total polyphenols and flavonoids of the extracts were measured to examine the constituents of functional materials. Flavor components and esters were identified in 3% sodium hydroxide and ethanol extracts. The content of polyphenols and flavonoids in ethanol extracts was higher than that of medicinal plants. 1wt.% of Tween 20 was added to disperse the essential oil components of the ethanol extract. Addition of a dispersant made it possible to produce a homogeneous mixture by having some compatibility with the ethanol extracts and the PVA molecule. When the concentration of the ethanol extract was 0.25 and 0.5wt%, relatively uniform PVA nanofiber having an average diameter of 350 to 365nm could be produced. The results of FT-IR, XRD and DSC analysis confirmed that Perilla Frutescens L. Britt ethanol extract was well mixed with PVA molecules and was electrospun.

• 한국염색가공학회지
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• 제18권6호
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• pp.16-24
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• 2006

The purpose of this study is to improve the defects of chitosan crosslinked viscose rayon by ECH and to describe the change of hand of chitosan crosslinked viscose rayon fabrics. The chitosan crosslinked viscose rayon were manufactured by crosslinking process using ECH as crosslinking agent, 2 wt% aqueous acetic acid as a solvent of chitosan and ECH, and 20 wt% aqueous sodium hydroxide as crosslinking catalyst. Viscose rayon were first immersed in the pad bath of the mixed solution of chitosan and ECH, padded up to 100 wt% wet pick-up on weight of fiber(owf), precured on pin frames at $130^{\circ}C$ for 2 minutes, immersed in NaOH solution and finally wash and dry. Antimicrobial properties of the viscose rayon treated with chitosan were measured by the shake flask C.T.M. 0923 test method with staphylococcus aureus(ATCC 6538) as the microorganism. When the concentration of chitosan was increased chitosan crosslinked viscose rayon's LT, WT, B, 2HB and MIU were increased and G, 2HG, SMD, T and $T_m$ were decreased. On the other hand, WT, EM were decreased and RT was increased at $1{\times}10^{-2}M$ ECH. The optimum condition for crosslinking was that ECH concentration was between $1{\times}10^{-2}M\;and\;5{\times}10^{-2}M$. Antimicrobial effects of rayon fabric treated with chitosan was excellent.

• 한국수소및신에너지학회논문집
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• 제16권2호
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• pp.130-135
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• 2005

Cadmium selenide is one of the group IIb-VI compounds, which is the promising semiconductor material due to its wide range of technological applications in optoelectronic devices such as photoelectrochemical cells, solid state solar cells, thin film photoconductors etc. CdSe has optical band gap of 1.7-1.8eV and proper conduction band edge for water splitting. CdSe films are coated with small thickness(20-50nm) nanocrystalline $TiO_2$ film by electrodeposition or chemical bath deposition methods and PEC properties of CdSe and CdSe/$TiO_2$ sandwich structure are studied. The photoactivity of CdSe and CdSe/$TiO_2$ films deposited on titanium substrate is studied in aqueous electrolyte of 1M NaOH solution. Photocurrent and photovoltage obtained were of the order of 2-4 mA/$cm^2$ and 0.5V, respectively, under the intensity of illumination of 100 mW/$cm^2$.

• 한국전기전자재료학회논문지
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• 제25권1호
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• pp.58-61
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• 2012

In our report a relatively simple process for fast nano-texturing of p-type(100) CZ- silicon surface using silver catalyzed wet chemical etching in aqueous hydrofluoric acid (HF) and hydrogen peroxide solution($H_2O_2$) at room temperature. The wafers were saw-damaged by NaOH(6 wt%) at $60^{\circ}C$ for 150s. To obtain a nano-structured black surface, a thin layer of silver with thickness of 1 - 10 nm was deposited on the surfaces by evaporation system. After this process the samples were etched in HF : $H_2O_2$ : $H_2O$ = 1:5:10 at room temperature for 80s - 220s. Due to the local catalytic of the Ag clusters, this treatment results in the nano-scale texturing on the surface. This resulted in average reflectance values less than 9% after the silver on the surface of the wafers were removed.

• 약학회지
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• 제33권2호
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• pp.80-86
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• 1989

2,6-Dimethyl-4-(3'-nitrophenyl)-1,4-dihydropyridine-3,5-dicarboxylic acid 3-methyl 5-(2'-phenylsulfinyl) ethyl ester (10) or 2,6-Dimethyl-4-(2' or 3'-nitrophenyl)-1,4-dihydropyridine-3,5-dicarboxylic acid 3-alkyl 5-(2-methylsulfonyl) ethyl ester (14a, b, c) were hydrolyzed by treatment with NaOH in aqueous EtOH solution to give 2,6-Dimethyl-4-(3'-nitrophenyl)-1,4-dihydropyridine-3,5-dicarboxylic acid monomethyl ester (4b), 2,6-Dimethyl-4-(2'-nitrophenyl)-1,4-dihydropyridine-3,5-dicarboxylic acid monomethyl ester (4c) and 2,6-Dimethyl-4-(2'-nitrophenyl)-1,4-dihydropyridine-3,5-dicarboxylic acid monoisopropyl ester (4d) in 80 -90% yield. By the same procedure, 2,6-Dimethyl-4-(3'-nitrophenyl)-1,4-dihydropyridine-3,5-dicarboxylic acid 3,5-bis (2'-methylsulfonyl) ethyl ester (15) gave 2,6-Dimethyl-4-(3'-nitrophenyl)-1,4-dihydropyridine-3,5-dicarboxylic acid (4e) in 96% yield.

• 공업화학
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• 제5권3호
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• pp.443-450
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• 1994

Polyacrylic acid를 NaOH와 $NH_4OH$로 중화시켜 중화도가 다른 polyelectrolyte를 만든 후, 수용액 상에서 ethylene glycol diglycidyl ether(EGDE)로 가교시켜 안정한 상태의 젤을 얻었다. 안정한 젤이 얻어지는 가장 작은 polyelectrolyte의 농도인 $C_{gel}$은 polyelectrolyte의 extended from에도 불구하고 비슷한 분자량의 중성 고분자의 간과 비슷하였다. 전해질 고분자에 대한 scaling이론에 의하면 semi-dilute영역에서의 전해질 고분자용액은 분자량 의존성이 없어야 함에도 불구하고 gelation결과는 중성 고분자와 흡사한 분자량 의존성을 보이며 entanglement 농도인 $C^{**}$와 비교했을 때에도 $C_{gel}$은 훨씬 큰 값을 갖는다. 이는 고분자 전해질의 농도가 진해질수록 용액의 이온세기가 증가하여 extended from에서 coil form으로 변화되기 때문으로 보인다. 고분자 전해질의 중화도에 따른 gelation은 100% 중화된 시료의 $C_{gel}$값과 분자량 의존성에 있어 거의 비슷한 경향을 보이며 이는 고분자 전해질의 conformation변화가 이온세기에 상당히 민감함을 보여 준다. 고분자 전해질 수용액에 추가로 저분자량의 염을 가하면 고분자의 용액 속에서의 크기가 더욱 축소하여 더 큰 $C_{gel}$값을 보인다.

• 한국식품과학회지
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• 제26권6호
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• pp.665-669
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• 1994

고체상 추출법을 이용하여 우유와 cheese에 존재하는 유기산들을 분리 농축한 후 test-butyldimethylsilyl (TBDMS) 유도체화하여 GC와 GC-MS로 분석하였다. 치이즈에 존재하는 유기산들을 고체상추출하기 위해서는 먼저 치이즈를 중류수에 용해시킨 후 산성화시켜 용매 추출함으로써 염을 제거할 수 있었으며 이어 $NaHCO_3$ 포화 용액으로 추출해 낸 수용액총은 Chrocosorb P컬럼으로 고체상 추출하여 유기산들만을 선택적으로 얻을수 있었다. TBDMS 유도체화하기 전 유기산들을 triethylammonium 염으로 만들어 줌으로써 휘발성 유기산외 손실도 막을 수 있었다. 우유 및 4종류의 치이즈에서는 모두 31가지 유기산들이 동정되었는테 이 중 21가지가 지방산이었으며 나머지는 hydroxy 와 dioic acid류였다. 특히 치이즈의 향을 좌우하는 휘발성 지방산들이 다수 발견되었는데 치이즈외 종류에 따라 그 양적인 차이를 나타내어 특징적 GC 프로파일들을 나타내었다. 각 치이즈의 GC 프로파일외 유기산 조성만을 나타내도록 단순화시킨 Rl spectra로 표현한 결과, 각 치이즈의 패턴분별이 용이하였으며, Direct Comparison 법을 시도해 본결과, 999 ppt의 match quality를 나타내어 맹검시료가 Gouda 치이즈임을 알 수 있었다.