• Polymer(Korea)
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• v.29 no.6
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• pp.593-598
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• 2005

This work studied the loading capabilities and release behaviors of poly(ethylene-alt-maleic anhydride) (PEMAh)/poly(4-vinyl pyridine) (P4VP) multilayer films formed by the layer-by-layer(LbL) sequential self-assembly method, using Rodamine 6G(R6G) as an indicator. Thickness of the multilayer, and loading and subsequent release behavior of R6G from the multilayer were studied using UV-visible spectroscopy. The amount of R6G loaded in multilayer film increased linearly with increasing film thickness. pH-Sensitive permeability was observed, where lower pH environments increased both release rate and release amount. By additional assembling of PEMAh/poly(ethyleneimine) (PEI) capping layers on top of (PEMAh/P4VP)n multilayers, the release of R6G was better controlled.

• Journal of the Mineralogical Society of Korea
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• v.22 no.4
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• pp.289-295
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• 2009

The characteristics of phosphate desorption on kaolinite was studied by batch adsorptiondesorption experiments. Desorption procedure was carried out through sequential extraction method at pH 4. The phosphorous contents were measured using UV-VIS-IR spectrophotometer with 820 nm wavelength. The adsorption-desorption reaction of P on kaolinite was irreversible, and most of adsorbed P on kaolinite were not easily dissolved to aqueous solution, but may might be fixed on kaolinite surface. The desorption isotherms were well fitted with the Freundlich and Temkin equations in the case of short reaction and long reaction time, respectively. The desorption reaction was divided into the early fast reaction and the later slow reaction. The percentage of desorption generally decreased with increasing adsorbed P concentration and increasing desorption reaction time.

• Polymer(Korea)
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• v.37 no.6
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• pp.736-743
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• 2013

Novel carbazole based copolymers were synthesized by Suzuki coupling polymerization. (Diphenylene)vinylene and n-octyl was introduced to carbazole as pendants for reducing band gap and improving solubility, respectively. Thermal, photoluminescence and electro-luminescence of copolymers were studied for applying the emitting layer of polymer light emitting diode (PLED). Maximum UV-vis absorption and photoluminescence (PL) emission wavelength of copolymers showed 333~340 nm and 409~464 nm in solution state, respectively. The relative quantum yield using 9,10-diphenylanthracene as a reference was 25.8%. These copolymers exhibited high thermal stability ($T_d$ = $350^{\circ}C$) and good film forming ability. Good luminance was obtained at voltages lower than 8 V and the onset voltage was observed at 4.0 V.

• Journal of the Korean Chemical Society
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• v.55 no.3
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• pp.444-453
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• 2011

VO(II), ZrO(II), Hf(IV), $UO_2$(II), Sn(II), V(V)$O_3$, Ru(III), Cd(II), Ho(III) and Yb(III) complexes of N'-(2-hydroxybenzyl)-2-(phenylamino)acetohydrazide ($H_2L^1$, 1) and N'-((3-hydroxy-naphthalen-2-yl)methylene)-2-(phenylamino)-acetohydrazide ($H_2L^2$, 13) have been synthesized and characterized by elemental analyses, $^1H$ NMR, IR, UV-Vis, conductance, thermal analyses (DTA and TG). The spectral data showed that the ligands behave as neutral bidentate, monobasic bidentate, monobasic tridentate or bibasic tridentate ligand bonded to the metal ions through the azomethine nitrogen atoms, phenolic hydroxyl group in protonated or deprotonated form and enolic or ketonic carbonyl group. The ligands and their metal complexes exhibit higher antifungal and antibacterial inhibitory effects than parent ligands and the solution of metal ions. Most of metal complexes exhibit higher antifungal activity than standard antifungal drug (amphotricene B). It is also clear that the ligands and their metal complexes have higher antifungal activity than antibacterial activity.

• Journal of the Korean Chemical Society
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• v.66 no.2
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• pp.86-91
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• 2022

The manure made of chaff and sawdust as litter was collected separately at a cowshed of a livestock farm in Andondg city. The fermentation efficiency of excreta is greatly influenced by the type and characteristics of litter and a factor to be considered for reducing N and P, the causes of eutrophication. Changes in weight with temperature and constituents of sample were examined using TG-DTA and XRF, respectively. NO₂^-, NO₃^-, and PO₄^3- ions and NH₄⁺, T-P and T-N eluted from manure by rain were analyzed using ion chromatograph and UV/Vis spectrometry, respectively. As a result, the fermentation efficiency of excreta in sawdust manure is three times higher as compared with chaff manure. The higher the fermentation efficiency, ammonia nitrogen was highly de-nitrogenated and organic phosphorous were also changed into phosphorous ions. Furthermore, phosphorous ions can be removed by transforming insoluble salts such as calcium phosphate (CaHPO₄·3H₂O) and struvite (NH₄MgPO₄·6H₂O) with addition of Ca and Mg.

• Korean Chemical Engineering Research
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• v.61 no.3
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• pp.407-411
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• 2023

The urease is covalently immobilized on the surface of the magnetic particles to catalyze the conversion of urea to bicarbonate anion. The conversion was confirmed qualitatively using high-pressure liquid chromatography and UV/Vis spectrometry, and analyzed quantitatively with cyclic voltammetry. The amount of conversion with respect to time was measured and analyzed by the reaction rate equation to calculate a reaction rate constant of 0.0474 min-1. In the 1 to 3 cycles, a conversion percentage of over 90% was found, and it was possible to reuse the urease 8 times up to the percentage of 50%. It was also observed that the stability evaluated for storage for 30 days was maintained. As a result of this study, it can be seen that the urease covalently immobilized on the scaffold can be used for urea removal for the purpose of producing ultrapure water.

• Proceedings of the Korean Society of Dyers and Finishers Conference
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• 2012.03a
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• pp.48-48
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• 2012

화학센서는 분석물질과 감응물질간의 화학적 반응을 통해 분석물질을 선택적으로 인지하고 이를 통하여 특정물질을 실시간으로 분석할 수 있는 기술이다. 최근 화학센서로 색소를 이용하여 음이온을 진단/감응하는 기술이 각광 받고 있으며, 더불어 음이온을 선택적으로 인지함에 있어 검출하고자 하는 특정 음이온에 대한 민감도를 높이기 위한 노력이 계속되고 있다. 감응물질로 이용되는 색소는 주로 분자 내 전하 이동형 색소(intramolecular charge transfer dye)로 주위 환경 변화에 민감하게 반응하며, 자극에 따른 변화를 흡수와 발광, 굴절률의 변화 등으로 나타낸다. 또한 다양한 음이온 중 분석물질로써 연구 가치가 큰 음이온에는 플루오린화물(fluoride)이 있다. 이는 플루오린화물이 치아 보호와 골다공증에 중요한 역할을 하는 순기능을 가지는 반면 고농도 상태에서는 불소증(fluorosis)을 비롯한 악영향을 잠재적으로 가지기 때문에 그 양을 인지하는 것이 중요하게 여겨지기 때문이다. 따라서 본 연구에서는 2-(3,5,5-trimethylcyclohex-2-enylidene)-malononitirle과 indole-3-carboxaldehyde를 통하여 분자 내 전하 이동형 색소를 합성하고, $^1H$ NMR, GC-mas, EA로 합성된 색소의 물성을 분석하였다. 우선 반응물인 2-(3,5,5-trimethylcyclohex-2-enylidene)-malononitirle을 합성하기 위해 dimethylfor mamide(DMF) 용매 하에서 isophorone과 malononitrile을 12시간 반응시키고, 얻어진 결과물을 정제한다. 이후 indole-3-carboxaldehyde와 10시간 환류시켜 색소를 얻는다. 합성된 색소는 F 이온 검출에 이용되며, UV-vis 분광법을 이용하여 분석물질에 따른 흡수 정도와 강도 변화를 살펴본다. 연구의 최종적인 목적은 비단 진단/감응 색소의 합성이 아니라 나노 섬유 소재와 색소의 접합을 통해 진단/감응형 나노 섬유를 개발하는 것으로 이를 위해 전기방사법이 이용된다.

• Korean Chemical Engineering Research
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• v.51 no.4
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• pp.513-517
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• 2013

This study focused on the synthesis of $Nb_xSrTi_{1-x}O_3$ photocatalysts which partially inserted Nb ions with excellent ability of fluorescence into the perovskite structured $SrTiO_3$ frameworks and their photocatalytic hydrogen productions from methanol/water splitting corresponding to the molar ratios of Ti and Nb. The characteristics of the synthesized $SrTiO_3$ and $Nb_xSrTi_{1-x}O_3$ powders were analyzed by X-ray diffraction (XRD), energy dispersive X-ray spectrometer (EDS), and UV-Visible spectrometer. The hydrogen evolution from methanol/water photo-splitting was enhanced over $Nb_{0.05}SrTi_{0.95}O_3$ compared to those over $SrTiO_3$ and another $Nb_xSrTi_{1-x}O_3$; 4.9 mL of hydrogen gases was collected after 8 h when 0.5g of $Nb_{0.05}SrTi_{0.95}O_3$ catalyst was used in pH 10.

• Journal of Conservation Science
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• v.31 no.3
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• pp.299-308
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• 2015

Aim of this study is to identify dyestuff of the Dallryeong(official's robe in Joseon Dynasty, 16th century) excavated from Yuryang-dong, Cheonan, in 1996. For this purpose, extracted dyestuffs from Dallryeong fabric and from natural dyestuffs for red color(safflower, Sapanwood, Madder) which are presumed to have been used in the Dallryeong, are analyzed and compared by high performance liquid chromatography(HPLC). As a result, HPLC chromatogram of extracts of the Dallryeong's dyestuff and safflower are showed a peak at 17.5 minutes. The UV/Vis spectra of the samples are showed the maximum absorption wavelength at 519nm. This result is identical with the analysis of the previous studies on red dyestuff of safflower. In addition, the analysis of Mass Spectrometry(MS) showed the identical result of the peak with m/z 910. Following these results, excavated pink Dallryeong were considered to have been dyed with safflower.

• Korean Journal of Plant Resources
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• v.30 no.2
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• pp.152-159
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• 2017

The purpose of this study was to obtain basic data for using Aronia as a functional food material. The composition of anthocyanin was characterized and quantitated by LC-MS/MS, HPLC, and UV-VIS spectrophotometer techniques, respectively. The anthocyanin content was analyzed by temperature, time, pH, and the addition of citric acid. The UV-VIS spectrophotometer used for analysis of anthocyanin is less accurate than the LC-MS/MS method used in recent years. In the past, cyanidin-3-Glucoside was reported to be a major anthocyanin that contains Aronia. However, LC-MS/MS analysis in this study confirmed cyanidin-3-galactoside to be the major compound. The anthocyanin content of the Aronia powder began to decrease sharply at a temperature of $65^{\circ}C$ or higher when heated for 24 hours. In an aqueous solution of Aronia, the anthocyanin content was reduced by 50% at $65^{\circ}C$ for 10 hours and decreased by 85% at $85^{\circ}C$ within 10 hours. Above pH 8, the anthocyanin content was reduced by more than 50%. The results of this study will provide useful information to maintain anthocyanin content in the manufacturing process of Aronia. It could also be used to ensure the stability of anthocyanins in similar species of berries.