• Advances in nano research
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• v.10 no.3
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• pp.295-312
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• 2021

A new ionic liquid functionalized magnetic silica nanoparticle was synthesized and characterized and tested as an adsorbent. The adsorbent was used for magnetic solid phase extraction on ICP-MS method. Simultaneous determination of precious metal Au has been addressed. The method is simple and fast and has been applied to standard water and surface water analysis. A new method for separation/analysis of trace precious metal Au by Magnetron Solid Phase Extraction (MSPE) combined with ICP-MS. The element to be tested is rapidly adsorbed on CoFe2O4@SiO2@[BMIM]PF6 composite nano-adsorbent and eluted with thiourea. The method has a preconcentration factor of 9.5-fold. This method has been successfully applied to the determination of gold in actual water samples. Hydrophobic Ionic Liquids (ILs) 1-butyl-3-methylimidazole hexafluorophosphate ([BMIM]PF6) coated CoFe2O4@SiO2 nanoparticles with core-shell structure to prepare magnetic solid phase extraction agent (CoFe2O4@SiO2@ILs) and establish a new method of MSPE coupled with inductively coupled plasma mass spectrometry for separation/analysis of trace gold. The results showed that trace gold was adsorbed rapidly by CoFe2O4@SiO2@[BMIM]PF6 and eluanted by thiourea. Under the optimal conditions, preconcentration factor of the proposed method was 9.5-fold. The linear range, detection limit, correlation coefficient (R) and relative standard deviation (RSD) were found to be 0.01~1000.00 ng·mL-1, 0.001 ng·mL-1, 0.9990 and 3.4% (n = 11, c = 4.5 ng·mL-1). The CoFe2O4@SiO2 nanoparticles could be used repeatedly for 8 times. This proposed method has been successfully applied to the determination of trace gold in water samples.

• Composites Research
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• v.35 no.6
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• pp.456-462
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• 2022

Since natural fibers are highly flammable, it is not easy to make them flame retardant. In this study, a liquid flame retardant based on phytic acid, APTES, and Thiourea, which are flame retardant candidates derived from nature, was prepared and its performance was verified through flame retardant treatment and flame retardancy evaluation of bamboo fibers. When a liquid flame retardant is used, it is possible to treat a large amount of natural fibers with flame retardant treatment. Nine types of flame-retardant treated bamboo fibers were prepared according to the Taguchi design of experiment method. Thereafter, vertical burning test and microcalorimeter test were performed for flame retardancy evaluation, and the surface of natural fibers before and after flame-retardant treatment was compared using scanning electron microscope. The results show that phytic acid has a significant effect on improving the flame retardancy of natural fibers. Through microstructure analysis, it was assumed that the phytic acid helps flame retardant to uniformly adhere to the surface of natural fibers. If such research results are utilized, it is possible to make a large amount of natural fibers high flammability in an eco-friendly way, which is expected to be advantageous for the application of prototypes.

• Korean Journal of Materials Research
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• v.32 no.5
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• pp.270-279
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• 2022

In this study, N/S co-doped carbon felt (N/S-CF) was prepared and characterized as an electrode material for electric double-layer capacitors (EDLCs). A commercial carbon felt (CF) was immersed in an aqueous solution of thiourea and then thermally treated at 800 ℃ under an inert atmosphere. The prepared N/S-CF showed a large specific surface area with hierarchical pore structures. The electrochemical performance of the N/S-CF-based electrode was evaluated using both 3-electrode and 2-electrode systems. In the 3-electrode system, the N/S-CF-based electrode showed a good specific capacitance of 177 F/g at 1 A/g and a good rate capability of 41% at 20 A/g. In the 2-electrode system (symmetric capacitor), the freestanding N/S-CF-based electrode showed a specific capacitance of 275 mF/cm² at 2 mA/cm², a rate capability of 62.5 % at 100 mA/cm², a specific power density of ~ 25,000 mW/cm² at an energy density of 23.9 mWh/cm², and a cycling stability of ~ 100 % at 100 mA/cm² after 20,000 cycles. These results indicate the N/S co-doped carbon felts can be a promising candidate as a new electrode material in a symmetric capacitor.

• Archives of Pharmacal Research
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• v.23 no.1
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• pp.26-30
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• 2000

The enantiomers of the bronchodilator terbutaline were separated by reversed-phase high performance liquid chromatograhy after derivatization with 2,3,4,6-tetra-O-acetyl-\beta-D-glucopyranosyl isothiocyanate(GITC) reagent. The derivatization proceeded quantitatively within 1 h at room temperature. The corresponding diastereomeric thiourea derivatives were well resolved on an ODS column with acetonitrile-acetate buffer as a mobile phase. Elution orders of the diastereomers were confirmed by derivatization of R-(-)-terbutaline and S-(+)-terbutaline which were collected by semi-preparative chiral HPLC using Sumichiral OA-4700 column. The native fluorescence of terbutaline was quenched by derivatization with GITC. The detection limit was 25ng when monitored at UV 278 nm.

• Bulletin of the Korean Chemical Society
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• v.31 no.2
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• pp.351-354
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• 2010

Nickel nanoparticles (Ni NPs) appeared to exhibit the catalytic activity in one-pot cyclocondensation reaction for the preparation of 3,4-dihydropyrimidine-2(1H)-ones via Biginelli reaction from aromatic/heteroaromatic/aliphatic aldehydes, urea/thiourea and ethyl acetoacetate under microwave irradiation has been described. The UV absorbance spectra showed metallic Ni characteristics and appreciate with the particle size determined by Transmission electron microscopy (TEM). After reaction course the Ni NPs can be re-covered and reused without any apparent loss of activity.

• Journal of the Korean Chemical Society
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• v.58 no.5
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• pp.445-449
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• 2014

A convenient and efficient method has been developed for the one-pot synthesis of dihydropyrimidinones (DHPMs) compounds. Dihydropyrimidinone derivatives were synthesized in good yields using ethyl acetoacetate, aldehyde (aromatic and aliphatic) and urea or thiourea in the presence of ZnO nanoparticles as a catalyst in $H_2O$ as solvent at $80^{\circ}C$. This green chemistry procedure applied to the Biginelli reaction using ZnO nanoparticles as catalyst and illustrated as a rapid preparation of DHPMs in water as solvent. The products were identified by physical data (mp) by comparison with those reported in the literatures.

• BMB Reports
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• v.36 no.5
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• pp.488-492
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• 2003

Neurofilament-L (NF-L) is a major element of neuronal cytoskeletons and known to be important for neuronal survival in vivo. Since oxidative stress might play a critical role in the pathogenesis of neurodegenerative diseases, we investigated the role of copper and peroxide in the modification of NF-L. When disassembled NF-L was incubated with copper ion and hydrogen peroxide, then the aggregation of protein was proportional to copper and hydrogen peroxide concentrations. Dityrosine crosslink formation was obtained in copper-mediated NF-L aggregates. The copper-mediated modification of NF-L was significantly inhibited by thiol antioxidants, N-acetylcysteine, glutathione, and thiourea. A thioflavin-T binding assay was performed to determine whether the copper/$H_2O_2$ system-induced in vitro aggregation of NF-L displays amyloid-like characteristics. The aggregate of NF-L displayed thioflavin T reactivity, which was reminiscent of amyloid. This study suggests that copper-mediated NF-L modification might be closely related to oxidative reactions which may play a critical role in neurodegenerative diseases.

• Journal of Power System Engineering
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• v.4 no.2
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• pp.31-39
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• 2000

Relationships between the plating condition and the plating rate of the deposition film for the electroless plating of Co-Cu-P alloy were discussed in this report. The result obtained from this experiment were summarized as follow ; The optimum bath composition was consisted of 0.8 ppm thiourea as a stabilizing agent. Composition of the deposit was found to be uniform after two hours of electroless plating. Plating rates of nickel-catalytic surface and zincate-catalytic surface were found to be very closely equal, but the plating time of nickel-catalytic surface took longer than that of the zincated-catalytic surface.

• The Korean Journal of Food And Nutrition
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• v.12 no.2
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• pp.142-149
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• 1999

Moisture absorption rate of rice according to the soaking time was higher at $25^{\circ}C$ than 4$^{\circ}C$ and the op-timum soaking time was 1hr at $25^{\circ}C$. When the ratios of added water for rice cooking were 1.3 in an elec-tric cooker and pressure cooker and 1.7 in an Dookbaeki sensory an mechanically evaluation of cooked rice were highly evaluated. The total number of peak on gas chromatography profile were 89 in an press-ure cooker 56 in an electric cooker and 83 in an Dookbaeki and major volatile compounds of cooked rice were aliphatic hydrocarbons cyclic hydrocarbons aromatic hydrocarbons aldehydes alcohols ketones and thiourea. Furan that is in sweety was not detected in volatile components of cooked rice of electric cooker.

• Environmental Mutagens and Carcinogens
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• v.10 no.2
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• pp.119-126
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• 1990

본 최기형시험은 엘라스타제가 임신토끼와 태자에 미치는 영향을 조사할 목적으로 수행되었다. 시험은 임신된 New Zealand White 종의 토끼를 2개의 대조군 (제 1, 제 2대조군)과 3개의 투여군 (제 1, 제 2, 제 3투여군)으로 나누어 실시되었다. 제 1, 제 2, 제 3투여군에는 각각 엘라스타제 1, 2, 12, 120mg/kg을 임신 6일부터 18일까지 연일 경구투여하였으며, 같은 기간동안 제 1대조군과 제 2대조군에는 각각 10% skim milk 수용액과 ethylene thiourea 40mg/kg을 경구투여하였다. 임신 29일에 모든 모동물을 도살하여 모체와 태자를 검색하였다. 시험기간중 제 2대조군에서는 사료섭취량이 유의성있게 감소되었다 (P<0.01). 시험결과 황체수, 착상수, 생존태자수, 태자의 성비, 태자 및 태반중량에 있어서 각 군간 유의성있는 변화가 관찰되지 않았으며 태자의 외형검사, 애부장기 및 골격 검사에서도 군간 유의성있게 변화가 관찰되지 않았다. 이상의 결과로 미루어 본 시험에서 채택한 엘라스타제의 용량은 토기에 있어서 최기형 유발능이 없는 것으로 판단된다.