• Journal of the Society of Cosmetic Scientists of Korea
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• v.36 no.4
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• pp.281-288
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• 2010

In this study, we investigated anti-oxidative effects of Duchesnea indica extracts by using Oxygen Radical Absorbance Capacity (ORAC). The extracts were prepared with 0 %, 30 %, 50 %, 70 % and 100 % aqueous ethanol respectively. The 30 % EtOH D. indica extract showed higher ORAC activity than the other extracts. Therefore, we performed in vitro studies on cytotoxicity of NIH-3T3 cells and MMP-8 collagenase inhibition using by the 30 % EtOH extract. The 30 % EtOH extract showed no cytotoxicity and significant inhibition on MMP-8 collagenase. And we performed clinical studies for the anti-wrinkle effect of the Di-Wrinkle Free Cream. The cream formula was prepared with 2 % arbutin and 1 % D. indica extract. Twenty one healthy women volunteers, ages of 35 and 50, applied the cream on their faces twice a day for 8 weeks. The skin was evaluated with PRIMOS (phaseshift rapid in vivo measuring of human skin) system and analyzed by the student's paired t-test. The wrinkles on the eye region were reduced by 13 % based on the PRIMOS system after 8 weeks. In the safety study of the Di-Wrinkle Free Cream, no symptoms were observed such as erythema, edema, scaling, itching, stinging, burning, tightness and prickling by visual observation and medical examination of volunteers for 8 weeks. Moreover, there was no noticeable skin disorder during experience period. These results suggested that D. indica extracts could be applied as cosmeceuticals effective for anti-wrinkle.

• Fire Science and Engineering
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• v.29 no.2
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• pp.84-91
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• 2015

The purpose of this study is to suggest the reasonable model of the caliber in suction nozzle, the pressure of suction nozzle, and the flow rate about foam system of line proportioner type using in the pumpcar. To test this, the experimental study was accomplished on the ground of the standards for the Performance Certification and Product Inspection of Foam Fire-extinguishing Chemical Mixing Machine. Aqueous Film Forming Foam in 3% and pipe type air foam nozzle with line proportioner FE 40 type were used. Test result showed that the pressure of suction nozzle within the limits between 0.25 MPa and 0.35 MPa was appropriate when the caliber in suction nozzle is 4 mm. Also, the pressure of suction nozzle within the limits between 0.45 MPa and 0.60 MPa was appropriate in the higher pressure than 4 mm when the caliber in suction nozzle is 5 mm.

• Korean Chemical Engineering Research
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• v.46 no.1
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• pp.184-188
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• 2008

This study presented simple and efficient fabrication of chemical sensors for the detection of acidic gas using 1,3-bisdicyanovinylindane as an indicator because it can be promising materials having property of the rapid color change according to the variation of pH. The dissociation of proton and dye in acidic condition as changing of ion pairs give rise to dramatically change the absorbance intensity of 1,3-bisdicyanovinylindane, which can be easily applied to the development of chemical sensors. In addition, indicator dyes having negatively charge in aqueous phase can be easily fabricated using layer-by-layer (LBL) methods by way of electrostatic interaction. For the proof of concept, we demonstrated the abrupt presentation of skeleton symbol on the chemical sensor, which could be resulted from the reaction of 1,3-bisdicyanovinylindane as background color with acidic gas. Thus, the rapid appearance of symbol will induce user's caution under the emergency condition. The presented chemical gas sensor using 1,3-bisdicyanovinylindane have strong advantages. First, the fabrication process of gas sensor was very simple and low-cost. Secondly, sensors reacted by acidic gas could be reused for several times. Finally, the chemical gas sensor would be environmentally friend, which can be a basic tool for the realization of eco-organic sensor device.

• KSBB Journal
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• v.22 no.6
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• pp.409-413
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• 2007

Polydiacetylene(PDA)-based sensors possess a number of properties that can be successfully applied for label-free detection system. PDA is one of the most attractive color-generating materials, with growing applications as sensors. Here we introduce various PDA-based devices, used as biosensor, chemosensor, thermosensor, and optoelectronics sensor. In general, PDA liposomes and films are closely packed and properly designed for polymerization via 1,4-addition reaction to form an ene-yne alternating polymer chain. PDA-based two/three dimensional structures have been used for colorimetric or fluorescent devices, sensing biological as well as chemical components. This color-generating material also present a very high charge carrier mobility, allowing its application as field-effect transistor (FET). The immobilized PDA structures or films have distinct advantages for the detection of low concentration target molecules over the aqueous solution-based detection systems. In the present review, reported detection methods by using various PDA structures are summarized with updated references.

• Journal of the Society of Cosmetic Scientists of Korea
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• v.48 no.2
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• pp.135-146
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• 2022

In order to prevent microbial contamination and safely use cosmetics, it is essential to possess preservative power. In this study, the antifungal effect was confirmed by improving the preservative system of the aqueous dispersion formulation, which has a weak preservative power against fungi, and various preservative systems were established to strengthen the preservative power against fungi. Five kinds of raw materials (sodium anisate, p-anisic acid, caprylhydroxamic acid, o-cymen-5-ol, hydroxyacetophenone) that have a benzene ring structure having a hydroxyl group and exist as protonated form in cosmetic formulations expected to improve antifungal activity in cosmetics were selected, and the minimum growth inhibitory concentration of the raw materials was determined through MIC assay. It was confirmed that the preservative power against mold was improved through the preservative efficacy test of 4 types of water dispersion formulations (cream, lotion, toner, and sun cream) in which 4 types of raw materials showing antimicrobial activity against mold were added to the preservative system. When p-anisic acid was used, it was confirmed that the preservative activity against mold was strengthened without the effect of inhibiting the preservative power against bacteria and yeast in all four formulations.

• Clean Technology
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• v.28 no.3
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• pp.232-237
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• 2022

Biorefineries, in which renewable resources are utilized, are an eco-friendly alternative based on biomass feedstocks. Alginic acid, a major component of brown algae, which is a type of marine biomass, is widely used in various industries and can be converted into value-added chemicals such as sugars, sugar alcohols, furans, and organic acids via catalytic hydrothermal decomposition under certain conditions. In this study, ruthenium-supported activated carbon and magnesium oxide were mixed and applied to the depolymerization of alginic acid in a batch reactor. The addition of magnesium oxide as a basic promoter had a strong influence on product distribution. In this heterogeneous catalytic system, the separation and purification processes are also simplified. After the reaction, low molecular weight alcohols and organic acids with 5 or fewer carbons were produced. Specifically, under the optimal reaction conditions of 30 mL of 1 wt% alginic acid aqueous solution, 100 mg of ruthenium-supported activated carbon, 100 mg of magnesium oxide, 210 ℃ of reaction temperature, and 1 h of reaction time, total carbon yields of 29.8% for alcohols and 43.8% for a liquid product were obtained. Hence, it is suggested that this catalytic system results in the enhanced hydrogenolysis of alginic acid to value-added chemicals.

• Applied Chemistry for Engineering
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• v.33 no.4
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• pp.431-435
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• 2022

The reduction of nitrogen-containing compounds (NC) containing the model crude methylnaphthalene oil (CMNO) of 5 compounds system was experimentally studied by solvent extraction. The model CMNO consisting of 3 kinds of NC including quinolone (QU), iso-quinoline (IQU), indole(IN) and 2 kinds of bicyclic aromatic compounds such as 1-methylnaphthalene (1MNA), 2-methylnaphthalene (2MNA) as raw materials, as well as the aqueous solution of formamide as a solvent, were used. The increase in the volume fraction of water to the solvent at the initial state (y_w,0) sharply decreased, but the distribution coefficient and the yield of NC conversely increased the selectivity of NC based on 2MNA, and an increase in the volume fraction of solvent to feed (S/F) simultaneously increased the distribution coefficient, yield and selectivity of NC. The yields of QU, IQU and IN under constant conditions (y_w,0 = 0.1, S/F = 1, equilibrium temperature 303 K) were 30%, 31% and 10%, respectively, and selectivity was 15, 15 and 20, respectively. From the excellent yield and selectivity of NC, the formamide extraction method of this study was expected as a method for reducing the NC contained in the model CMNO.

• Resources Recycling
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• v.32 no.1
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• pp.21-32
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• 2023

Because the application of lithium has gradually increased for the production of lithium ion batteries (LIBs), more research studies about recycling using solvent extraction (SX) should focus on Li⁺ recovery from the waste solution obtained after the removal of the valuable metals nickel, cobalt and manganese (NCM). The raffinate obtained after the removal of NCM metal contains lithium ions and other impurities such as Na ions. In this study, we optimized a selective SX system using di-(2-ethylhexyl) phosphoric acid (D2EHPA) as the extractant and tri-n-butyl phosphate (TBP) as a modifier in kerosene for the recovery of lithium from a waste solution containing lithium and a high concentration of sodium (Li⁺ = 0.5 ~ 1 wt%, Na⁺ = 3 ~6.5 wt%). The extraction of lithium was tested in different solvent compositions and the most effective extraction occurred in the solution composed of 20% D2EHPA + 20% TBP + and 60% kerosene. In this SX system with added NaOH for saponification, more than 95% lithium was selectively extracted in four extraction steps using an organic to aqueous ratio of 5:1 and an equilibrium pH of 4 ~ 4.5. Additionally, most of the Na⁺ (92% by weight) remained in the raffinate. The extracted lithium is stripped using 8 wt% HCl to yield pure lithium chloride with negligible Na content. The lithium chloride is subsequently treated with high purity ammonium bicarbonate to afford lithium carbonate powder. Finally the lithium carbonate is washed with an adequate amount of water to remove trace amounts of sodium resulting in highly pure lithium carbonate powder (purity > 99.2%).

• Journal of the korean academy of Pediatric Dentistry
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• v.26 no.2
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• pp.262-274
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• 1999

Several alternatives for increasing the fluoride concentration in the mouth, such as water fluoridation, ingestion of fluoride supplements, fluoride paste, fluoride mouthrinse, application of fluoride gel are available. There is an impressive body of evidence that the topically deliverd fluorides are clinically effective in inhibiting the progression of dental caries. Recent studies on the cariostatic action of fluoride have indicated the importance of fluoride in the fluid environment of the teeth. The fluoride levels in unstimulated whole saliva can be considered indicative of F in the aqueous phase available for interaction with the tooth surface at a given time. The retention of F in the mouth after topical fluoride treatment is considered to be an important factor in the clinical efficacy of F. The aim of this study was to determine the elevation and clearance of fluoride in whole saliv after the following topical flouride treatments using HMDS-diffusion technique and fluoride ion electrode. The obtained results were as follow: 1. Average salivary fluoride concentration in the unstimulated whole saliva was $0.0152ppm{\pm}0.0091ppm$. Unstimulated salivary flow rate was between 0.34-0.36ml/min and there was no statistically significant difference among the groups(p>0.05). 2. Except for the immediate time after treatment, fluoride levels followed as APF gel>neutral gel>F-rinse>F-paste. There was no statistical difference between the salivary F concentration of F-paste group and that of control group after 2 hours. In case of F-rinse group, after 3 hours the concentration had dropped to baseline value. But there was statistically significant difference among the F concentraion of F gel groups and that of control group(p<0.05). 3. The mean $AUC_{0-120min}$ values were followed as neutral gel>APF gel>F-rinse>F-paste, and the values of the two former groups were significantly higher than those of the two latter groups(p<0.05).

• Journal of the Korean Chemical Society
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• v.37 no.11
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• pp.951-960
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• 1993

$Hg^{2+}$-induced aquation trans-[Co(3,2,3-tet)$X_2]^+$(3,2,3-tet = 4,7-diazadecane-1,10-diamine, $X_2\;=\;Cl_2,\;(NO_2)Cl,\;Br_2,\;(NO_2)Br,\;(NO_3)_2)$ complexes was investigated in aqueous solution. The products and the reaction mechanism were confirmed by chromatography, UV/Vis. spectrum, and circular dichroism (CD) spectrum. From the results, $Hg^{2+}$-induced aquation of 3,2,3-tet system has been produced cis-${\beta}$ complex via trans complex. The kinetic studies on $Hg^{2+}$-induced aquation of trans-[Co(3,2,3-tet)$Cl_2]^+$ complex and trans-[Co(3,2,3-tet)$(NO_2)Cl]^+$ complex were also carried out to study the reaction mechanism. The results show that trans-[Co(3,2,3-tet)$Cl_2]^+$ complex undergoes the D(dissociative)-mechanism and trans-[Co(3,2,3-tet)$(NO_2)Cl]^+$ complex $I_d$(interchange dissociavite)-mechanism. In order to confirm steric course for the reaction mechanism, $Hg^{2+}$-induced aquation on trans-[Co(R,R-3,2,3-tet)$Cl_2]^+$ complex to which chiral R,R-3,2,3-tet was coordinated instead of the racemic(R,R:S,S) 3,2,3-tet was used has been examined by CD spectrum. From the results, the final complex was confirmed to be ${\Delta}-cis-{\beta}$-[Co(R,R-3,2,3-tet)$(OH_2)_2]^{3+}$ complex indicating the chirality was retained through whole process.