• YAKHAK HOEJI
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• v.27 no.2
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• pp.169-176
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• 1983

The verification of genuine sesame oil can be examined by determination of the ratio of fatty acid. Fatty acids were extracted from the saponifiable substance of sesame oils. Fatty acids were methylated with the 14% boron trifluoride methanol solution and injected into a gas chromatograph with Unisole 3000 column and finally determined the molecular weight by mass spectrometry. The fatty acids in laboratory prepared sesame oils were composed mainly of oleic acid 36.7-42.8% and linoleic acid 39.0-46.6%, including palmitic acid 7.9-9.l%, stearic acid 4.1-5.6%, linoleic acid 0.1-3.0%, arachidic acid 0.5-1.0% and eicosenoic acid 0.1-0.5%. The above results allow the estimation of genuine sesame oil, mixed with rape seed oil, soybean oil, perilla oil, etc. In 53 samples, 14 samples were estimated as genuine and it was found that erucic acid was contained in 31 samples, linoeic acid was highly contained in 14, high quantity of linolenic acid was in 7 and palmitic and oleic acid were highly involved in 3.

• Corrosion Science and Technology
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• v.21 no.6
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• pp.423-433
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• 2022

The objective of this study was to determine whether Cymbopogon citratus extract as a corrosion inhibitor from natural tropical resources could prevent corrosion of carbon steel in sulfuric acid solution. Inhibitory action of this extract was investigated using electrochemical methods such as potentiodynamic polarization and electrochemical impedance spectroscopy (EIS). Those methods revealed corrosion rate, efficiency of inhibition, and adsorptions isotherm values when the extract was added to the sulfuric acid solution at concentration up to 500 ppm with various immersion time at ambient temperature. Results revealed that higher concentration of the extract and longer immersion time decreased the corrosion rate of carbon steel whereas the inhibition efficiency of the extract was increased up to 97.25%. The value of charge transfer resistance was increased significantly by adding the extract at concentration up to 500 ppm with an immersion time of 60 minutes. The type of the extract was a mixed inhibitor. It could inhibit the corrosion process in both anodic and cathodic sides electrochemically. Results of this study suggest that the mechanism of adsorption on the surface of carbon steel is related to Langmuir adsorption isotherm.

• Mass Spectrometry Letters
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• v.8 no.1
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• pp.14-17
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• 2017

The effect of cationization agent concentration on glycan detection via matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS) was investigated using $Na^+$ ions in the form of NaCl as the cationization agent. NaCl solution concentrations ranging from 1 mM to 1 M were investigated. Glycans from ovalbumin were mixed with the cationization agent solution and the 2,5-dihydroxybenzoic acid (2,5-DHB) matrix solution in a volume ratio of 1:1:1. The resulting mixture was loaded onto the MALDI plate. Two MALDI-TOF MS instruments (Voyager DE-STR MALDI-TOF MS and Tinkerbell RT MALDI-TOF MS) were used for detection of glycans. The best detection, in terms of the number of identified glycans, the peak intensity, and the signal-to-noise (S/N) ratio, was obtained with NaCl concentrations of 0.01-0.1 M for both MALDI-TOF MS instruments.

• Journal of Biomedical Engineering Research
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• v.38 no.1
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• pp.1-8
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• 2017

The successful synthesis of hyaluronic acid micro-threads is very promising approach for the broad application in tissue engineering such as dermal fillers. Because hyaluronic acid has the excellent biocompatibility and ability to maintain the moisture of up to several hundred times its own weight. In order to generate the hyaluronic acid micro-threads in microfluidic system, we employed two-phase flow microfluidic chip to make a rapid synthesis of the hyaluronic acid hydrogel. Hyaluronic acid was mixed with 0.02N NaOH solution and 1, 4-Butanediol diglycidyl ether (BDDE) solution and then injected into core channel. The ethanol was used for the 3-dimensional micro-thread formation in sheath channel. We manipulated the diameter of HA micro-threads using controlling of flow rates in microfluidic chip, and showed the feasibility of immobilization in HA micro-threads with florescent substances. Also, the generated HA micro-threads were evaluated and showed the suitable properties with tensile strength, bending property, and swelling profiles for dermal fillers. As a result, we suggested an innovative method for microfluidic chip-based HA micro-threads which could safely be applied as dermal filler in tissue engineering.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2007.11a
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• pp.485-486
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• 2007

• Applied Chemistry for Engineering
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• v.5 no.2
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• pp.223-229
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• 1994

The effect of agitation speed on mass transfer coefficient in the extraction of citric acid from mixed aqueous solutions of citric and acetic acid with n-butylacetate solutions of di-isotridecylamine(DITDA) and 50% mixture of tri-n-octyl and try-n-hexyl phosphine oxide(MOHPO), were studied in batch extractor. Experimental results showed that the degree of extraction was higher with increasing agitation speed, and was best at 200rpm and 30 minutes in batch extractor. The higher degree of extraction was obtained in mixed solution of citric-acetic acid by using DITDA than MOHPO as an carrier. Mass transfer coefficient was proportional to the degree of extraction, and $K_r=1.254{\times}10^{-3}Re^{0.536}$ was found for she extraction of citric acid by DITDA.

• Journal of the Mineralogical Society of Korea
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• v.23 no.3
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• pp.183-189
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• 2010

It is of importance to separate Ni(II) and Co(II) from Mg(II) in solution which was leached from nickel laterite ore. In order to investigate the possibility of separating Ni(II) and Co(II) from Mg(II), adsorption behavior of the three metals from individual and mixed sulfate solutions was investigated by using Diphonix resin. The concentration of each metal in solution was fixed at 100 ppm and the pH of the sulfuric acid solution was changed from 5 to 7. At ambient temperature, the adsorption behavior of the three metal ions followed Langmuir adsorption isotherm. The loading capacity of Diphonix resin for the three metal ions was obtained from the Langmuir isotherm. Since adsorption behavior of the three metal ions from the mixed solution was similar to each other, it was found to be difficult to separate Ni(II) and Co(II) from Mg(II) by using Diphonix resin.

• Textile Coloration and Finishing
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• v.3 no.4
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• pp.17-21
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• 1991

A rigid polymer, cellulose triacetate (CTA) dissolved in a combination of trifluoroacetic acid (TFA) and methylene chloride (MC) solution are liguid crystalline above a certain concentration. A flexible polymer, polyethylene terephthalate (PET) also dissolves in TFA/MC, but does not form liguid crystal phase. Ternary solutions, CTA/PET/TFA-MC which CTA and PET were mixed in a same solvent TFA/MC (6/4 : v/v) showed phase separation and mesophase formation.

• Applied Chemistry for Engineering
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• v.20 no.5
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• pp.557-560
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• 2009

In this study, a new wet etching method and the solution for thinning the glass with the thickness below $100{\mu}m$ were investigated. For the preparation of etching solution with low hydrofluoric acid, it was effective to use $NH_4F$ or $NH_4HF_2$ as a main ingredient with the addition of sulfuric acid or nitric acid. Influence of the composition of mixed acid solution and the temperature on the etching rate was investigated. The addition of anionic surfactant provides the function to prevent the adhesion of sludge generated by the etching reaction. A new wet etching pilot device equipped with streaming generation parts was used to test etching of commercial non-alkali glass and soda lime glass. The non-alkali glass with the thickness of 640 ${\mu}m$ and soda lime glass with the thickness of $500{\mu}m$ were etched to $45{\mu}m$ and $100{\mu}m$, respectively, by using the pilot device. After the etching by pilot device, the roughness degree of the glass surface was maintained at $0.01{\sim}0.02{\mu}m$.

• Korean Journal of Materials Research
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• v.27 no.2
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• pp.113-118
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• 2017

Natural and expandable graphites were chemically treated in acidic aqueous solutions such as acetic acid or mixtures of acetic acid and nitric acid. Structures and thermal conductivities of the as-treated graphites were characterized in detail. Both graphites were significantly oxidized in the mixed acidic solution of $H_2SO_4$ and $HNO_3$, which condition was generally used for the oxidation of carbon nanotubes. This considerable oxidation of graphites caused a depression of their thermal conductivity. The structural characteristics, obtained by XRD and XPS, show that the graphites treated in the relatively weak acidic conditions (acetic acid or mixture of acetic acid and nitric acid) were quite similar to the untreated graphites. However, the thermal conductivities of both acidic-treated graphites were remarkably increased.