• Bulletin of the Korean Chemical Society
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• 제27권9호
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• pp.1293-1296
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• 2006

In this study, a solid phase extraction method has been developed for the preconcentration and separation of the elements Cr(III), Fe(III), Co(II) and Pb(II) at trace levels by using a column packed with Amberlite XAD-1180 resin loaded with 4-(2-pyridylazo)-resorcinol (PAR) reagent. After preconcentrating, the metals retained on the column were eluted with 20 mL of 3 mol/L $HNO_3$ and then determined by flame atomic absorption spectrometry (FAAS). The factors affecting the recovery of the elements, such as pH, type and concentration of eluent, volume of sample and elution solution, and matrix components, were also ascertained. The recoveries of Cr(III), Fe(III), Co(II) and Pb(II) were found to be $99\;{\pm}\;4,\;97\;{\pm}\;3,\;95\;{\pm}\;3$ and $98\;{\pm}\;4$%, respectively, under the optimum conditions at 95% confidence level and the relative standard deviations found by analyzing of nine replicates were $\leq4.4$%. The preconcentration factors for Cr(III), Fe(III), Co(II) and Pb(II) were found as 75, 125, 50 and 75 respectively. The detection limits (DL, 3s/b) were 3.0 $\mu g/L$ for Cr(III), 1.25 $\mu g/L$ for Fe(III), 3.3 $\mu g/L$ for Co(II), and 7.2 $\mu g/L$ for Pb(II). The recoveries achieved by adding of metals at known concentrations to samples and the analysis results of Buffalo river sediment (RM 8704) show that the described method has a good accuracy. The proposed method was applied to tap water, stream water, salt and street dust samples.

• Journal of Microbiology and Biotechnology
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• 제26권12호
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• pp.2051-2059
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• 2016

To date, there has been no employment of a magnetoelastic (ME) biosensor method to detect Salmonella enterica serovar Typhimurium in soil. The ME biosensor method needs to be investigated and modified for its successful performance. The filtration method, cation-exchange resin method, and combinations of both methods were employed for the extraction of S. Typhimurium from soil. The number of S. Typhimurium and the resonant frequency shift of the ME sensor were then compared using a brilliant green sulfa agar plate and an HP 8751A network analyzer. A blocking study was performed using bovine serum albumin (BSA), polyethylene glycol (PEG), and casein powder suspension. Finally, the modified ME biosensor method was performed to detect S. Typhimurium in soil. The number of S. Typhimurium was significantly decreased from 7.10 log CFU/soil to 4.45-4.72 log CFU/soil after introduction of the cation-exchange resin method. The greatest resonant frequency shift of the measurement sensor was found when employing centrifugation and filtration procedures. The resonant frequency shift of the PEG-blocked measurement sensor was $3,219{\pm}755Hz$, which was significantly greater than those of the BSA- and casein-blocked ME sensor. The optimum concentration of PEG was determined to be 1.0 mg/ml after considering the resonant shift and economic issue. Finally, the modified ME biosensor method was able to detect S. Typhimurium in soil in a dose-response manner. Although these modifications of the ME biosensor method sacrificed some advantages, such as cost, time effectiveness, and operator friendliness, this study demonstrated a novel approach of the ME biosensor method to detect S. Typhimurium in soil.

• 한국의류학회지
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• 제13권1호
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• pp.59-66
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• 1989

This paper is concerned with formaldehyde release from durable press finished rayon fabrics. $100\%$ rayon fabrics were treated with 3 kinds of commercial N-methylol crosslinking agents using a pad-dry cure technique. Aqueous extractions of fabric samples were carried out at $40^{\circ}C$ under pH's of 4, 7, 10. Formaldehyde release was evaluated for the types of resins, catalyst concentrations and extraction conditions. Results indicated that the higher concentration of catalyst leads to the more fixation of resin on the fabric. Total formaldehyde released to the extract was decreased as the catalyst concentration increased. For the resin types, the amount of formaldehyde released was in the order of DMU>MDMDHEU>DMDHEU. Free formaldehyde content in the extract was in the order of pH10>pH4>pH7. This result proved that resins are least resistant to alkaline hydrolysis and the N-C bond cleavage under alkaline condition. Under acidic condition, however, N-methylol formaldehyde was accumulated before the release of free formaldehyde. This suggested the C·0 bond cleavalge to form carbonium - immonim intermediate.

• 자원리싸이클링
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• 제7권2호
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• pp.9-15
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• 1998

석유 탈황 폐촉매 중의 바나듐을 습식법으로 회수한 후의 라피네이트로부터 몰리브덴을 회수하기 위한 연구를 수행하였다. 이 라피네이트의 조성은 Mo 1,100 ppm, V150ppm, Al 19 ppm, Ni 33 ppm으로 이루어져 있으며, 이 수용액 중의 몰리브덴을 효율적으로 분리.회수하기 위하여, 킬레이트수지에 의한 흡착 또는 3급 아민에 의한 용매추출법에 의하여 분리하는 방법을 적용하였다. 킬레이트수지에 의한 Mo의 흡착은 폴리에틸렌 아민형 킬레이트수지에 의하여 몰리브덴을 선택 흡착시킨 후, $3.0mol/{dm}^{3}$-$NH_4$OH을 용리제로 사용하여 $60g/{dm}^{3}$의 몰리브덴으로 농축할 수 있었다. 한편, 용매추출법으로는 2N-HCl으로 접촉시켜 전처리한 10vol%-Alamine 336에 의하여 몰리브덴이온은 전 pH 범위에서 100%의 추출율을 나타내었다.

• 한국가구학회지
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• 제22권3호
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• pp.174-182
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• 2011

Over the last decade, Sick Building Syndrome has become a significant social issue in Korea and many methods have been considered to maintain comfortable indoor air quality. To reduce toxic substances emitted from wood composite products, the source control is an efficient method through the reduction of formaldehyde content by using natural material-based adhesives for composite wood products production. Among alternative materials, soybean protein is considered an appropriate natural material to replace formaldehyde-based resin and many efforts have been made to produce new products, such as soap, shampoo, ink, resin, adhesive and textile through changing the chemical or physical properties of soybean. To process soybeans into these useful products, the beans are dehulled and the oil is removed by crushing at very high pressure or by solvent extraction. For use soybean as an adhesive, it is processed at temperatures below $70^{\circ}C$ to preserve the alkaline solubility of the proteins. In addition, soybean-based adhesive is undergone treatment process to improve mechanical properties using urea, urease inhibitor N-(n-butyl) thiophosphoric triamide and sodium dodecyl sulfate. The modified soybean-based adhesive exhibited sufficient mechanical properties to use as an adhesive for composite wood products. This paper is a review article to discuss the possibilities of soybean-based adhesive for environment-friendly furniture materials.

• Journal of the Korean Wood Science and Technology
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• 제24권1호
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• pp.95-99
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• 1996

The bending and compression strength properties of two types Rhus verniciflua specimens, which made of no heat-treated wood and heat-treated wood for urushiol extraction, were measured. The heat-treated specimens were finger-jointed with either resorcinol-phenol or polyurethane resin adhesives, and the vertical type bending strength property was also measured in these specimens. The results obtained are as follows ; 1. The correlation coefficient between the compression strength and specific gravity in the specimens of no heat-treated and heat-treated wood was high. However there was no difference in compression strength property as affected by heat treatment. 2 The correlation coefficient between the bending strength and specific gravity in the specimens of no heat-treated and heat-treated wood was also high. However, there was no difference in bending strength property as affected by heat treatment. 3 The bending test showed high correlation between modulus of elasticity and modulus of rupture for the specimens made of no heat-treated and heat-treated wood. However, there was no difference in bending strength property between the specimens made of heat-treated and no heat-treated wood. 4. The efficiencies of bending strength test on the finger-jointed specimens of heat-treated wood with resorcinol-phenol and polyurethane resin adhesives were 0.85, 0.81. respectively.

• Restorative Dentistry and Endodontics
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• 제45권2호
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• pp.15.1-15.7
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• 2020

This clinical report describes designing and fabricating a single-retainer resin-bonded fixed dental prosthesis with a chair-side computer-aided design/computer-aided manufacturing system. The whole procedure, from tooth extraction to final placement of the prosthesis, was completed in one day, and a single clinic visit. No clinical complications were found at the 2-year follow-up after placement of the restoration, and satisfactory functional and esthetic results were achieved.

• 생명과학회지
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• 제27권10호
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• pp.1145-1151
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• 2017

세제에 의하여 대장균의 periplasm에서 penicillin G amidase (PGA)를 방출하는 방법을 연구하였다. 결과적으로 세제와 lysozyme의 혼합 작용이 효과적인 것으로 나타났다. 세포 투과성의 최적 조건을 알아보기 위하여 세제의 종류, 농도, pH, 반응 시간, 온도 등의 영향을 살펴보았다. 그리하여 대장균에서 재조합 PGA를 periplasm에서 방출하는 모델을 만들 수 있었고 방출된 PGA를 농축할 수 있었다. 실리카 구슬을 이용한 고정화 시스템으로 PGA 용액을 농축할 수 있었으며, 더 이상의 정제 과정 없이 순수하게 추출 할 수 있었다. 고정화된 PGA는 penicillin G 생성의 원료인 6-APA를 생산하는데 사용할 수 있었다. 이 방법은 대장균으로부터 재조합 단백질을 추출하는 간단한 방법이며 고정화 PGA를 이용하여 ${\beta}-lactam$ 항생물질의 산업적 생산 이용될 수 있을 것으로 사료된다.

• 분석과학
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• 제35권2호
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• pp.53-59
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• 2022

Mugwort (Artemisia montana), which is a perennial plant mainly distributed throughout Northeast Asian regions, has been used as a preferred source of various foods and traditional medicines in Korea. In particular, as essential oils extracted from mugwort were reported to be biologically active, its steam distillate has been widely used to treat various conditions, such as itching, hemorrhoids, and gynecological inflammation. Therefore, efforts have been devoted to develop effective methods for the collection of bioactive essential oils from mugwort. In this study, five mugwort extracts were obtained using different extraction conditions, namely, 6 % ethanol at room temperature and at 80 ℃, pure ethanol, n-hexane, and an adsorbent resin. To evaluate the five extracts of mugwort, area-under-the-curve values (AUCs), chemical profiles, and major bioactive essential oil contents were investigated using gas chromatography-mass spectrometry (GC-MS). An overall assessment of the volatile components, including essential oils, in the five extracts was conducted using AUCs, and the individual essential oil in each extract was identified. Furthermore, the four major essential oils (1,8-cineole, camphor, borneol, and α-terpineol), which are known to possess anti-microbial and anti-inflammatory activities, were quantified using authentic chemical standards. Based on the evaluation results, pure ethanol was the best extractant out of the five used in this study. This study provides evaluation results for the five different mugwort extracts and would be helpful for developing extraction methods to efficiently collect the bioactive oil components for medical purposes using chemical profiles of the extracts.

• 분석과학
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• 제16권2호
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• pp.102-109
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• 2003

오줌시료 중 미량 알루미늄을 혹연로 원자흡수 분광광도법 정량하기 위한 마이크로파삭힘 및 고체상 추출에 관하여 연구하였다. 시료에 질산과 과산화수소를 가하고 가정용 전자레인지로 유기물을 파괴시킨 다음 오븐에서 건조시킨다. 건조된 찌기를 황산으로 녹이고, 이를 8-hydroxyquinoline (Oxine, HQ)이 흡착된 XAD-4 수지의 칼럼에 통과시켜 Al(III)-8-hydroxyquinolinate 착물을 형성시켜 흡착시킨다. 칼럼으로부터 0.5 M 질산으로 용리한 Al(III)을 정량하였다. 이 실험과정에서 찌기를 녹이기 위한 산의 종류, 수지에 흡착시키는 HQ의 양, 녹인 시료용액의 pH, 칼럼에 고정된 착물의 용리를 위한 산의 종류와 농도 등의 실험조건을 검토하여 최적화 시켰다. 인공 오줌 시료를 바탕으로 최적화 실험을 하였으며 검정곡선을 작성하였다. 실제 시료 중 알루미늄을 정량하였고, 표준용액을 일정량 첨가한 시료에서 구한 회수율은 94~101% 이였다. 바탕 세기에 대한 표준 편차의 3배 세기에 해당하는 검출한계는 0.05 ng/mL 이었다. 이로서 본 방법이 오줌시료 중 알루미늄을 분리하여 정량하는데 응용될 수 있음을 알 수 있다.