• Analytical Science and Technology
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• v.31 no.4
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• pp.171-178
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• 2018

Recently, for successful lactation, many breastfeeding mothers seek various products, including herbal medicine, dietary supplements, and prescribed medicines, to improve milk production. As demand for galactogogues grows, it is highly possible that pharmaceutical galactogogues may be adulterated with illegal products to maximize their efficacy. For continuous control and supervision of illegal products, we developed and validated a simple and sensitive LC-MS/MS method capable of simultaneously determining five galactogogues. Chromatographic separation was conducted using an Agilent Poroshell $120SB-C_{18}$ column with a mobile phase consisting of 20 mM ammonium formate (pH 5.4) and 100 % acetonitrile. The total run time was 13 min per analyte. The proposed method was performed according to the guidelines of the International Conference of Harmonization and it produced reliable results. This method showed high sensitivity and specificity, with a limit of detection (LOD) and limit of quantitation (LOQ) of 0.01-0.82 ng/mL and 0.02-2.45 ng/mL, respectively, for the solid- and liquid-type samples. Specificity was evaluated by analyzing matrix-blank samples spiked with the target compounds at LOQ levels, which provided a good separation of all peaks without interference. Additionally, the repeatability and intermediate precision were typically <15 %, whereas the recovery was 80-120 % of the values obtained using blank samples. Thus, we concluded that this method could be used for the identification and quantification of galactogogues in food or herbal products.

• Journal of Technologic Dentistry
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• v.31 no.1
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• pp.55-61
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• 2009

Passive fitting of meso-structure and super-structures is a predominant requirement for the longevity and clinical success of osseointegrated dental implants. However, precision and passive fitting has been unpredictable with conventional methods of casting as well as for corrective techniques. Alternative to conventional techniques, electro discharge machining(EDM) is an advanced method introduced to dental technology to improve the passive fitting of implant prosthesis. In this technique material is removed by melting and vaporization in electric sparks. Regarding the efficacy of EDM, the application of this technique induces severe surface morphological and elemental alterations due to the high temperatures developed during machining, which vary between $10,000{\sim}20,000^{\circ}C$. The aim of this study was to investigate the morphological and elemental alterations induced by EDM process of casting dental gold alloy and non-precious alloy used for the production of implant-supported prosthesis. A conventional clinical dental casting alloys were used for experimental specimens patterns, which were divided in three groups, high fineness gold alloy(Au 75%, HG group), low fineness gold alloy(Au 55%, LG group) and nonprecious metal alloy(Ni-Cr, NP group). The UCLA type plastic abutment patterns were invested with conventional investment material and were cast in a centrifugal casting machine. Castings were sandblasted with $50{\mu}m\;Al_2O_3$. One casting specimen of each group was polished by conventional finishing(HGCON, LGCON, NPCON) and one specimen of each group was subjected to EDM in a system using Cu electrodes, kerosene as dielectric fluid in 10 min for gold alloy and 20 min for Ni-Cr alloy(HGEDM. LGEDM, NOEDM). The surface morphology of all specimens was studied under an energy dispersive X-ray spectrometer (EDS). The quantitative results from EDS analysis are presented on the HGEDM and LGEDM specimens a significant increase in C and Cu concentrations was found after EDM finishing. The different result was documented for C on the NPEDM with a significant uptake of O after EDM finishing, whereas Al, Si showed a significant decrease in their concentrations. EDS analysis showed a serious uptake of C and Cu after the EDM procedure in the alloys studied. The C uptake after the EDM process is a common finding and it is attributed to the decomposition of the dielectric fluid in the plasma column, probably due to the development of extremely high temperatures. The Cu uptake is readily explained from the decomposition of Cu electrodes, something which is also a common finding after the EDM procedure. However, all the aforementioned mechanisms require further research. The clinical implication of these findings is related with the biological and corrosion resistance of surfaces prepared by the EDM process.

• Korean Journal of Environmental Agriculture
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• v.20 no.4
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• pp.269-276
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• 2001

Several experiments including persistence, distribution, leaching, and terminal residue trials were carried out to investigate the behavior of cyclosulfamuron in rice paddies. Cyclosulfamuron was gradually dissipated in two different soils showing the first-order kinetics. Half-lives of the herbicide were calculated to be $17{\sim}30$ and $14{\sim}16$ days under field and laboratory conditions, respectively. In the paddy soil/water system, the residue tended to reside more in the soil phase as time elapsed. Cyclosulfamuron was less persistent in paddy water than in soil with half-lives of 10 and 19 days, respectively. No cyclosulfamuron was leached below 20 cm-deep soil during water percolation with 50 cm hydraulic head, while some downward mobility was observed within the soil column. When EC and SC formulations of cyclosulfamuron were applied to the paddy field at 120 or 150-day pre-harvest intervals, its terminal residues in hulled rice were all less than 0.01 mg/kg, irrespective of formulation type and application timing. In rice straw, however, some residues were found at $<0.02{\sim}0.05$ mg/kg as SC formulation was applied. Rapid dissipation, restricted mobility, and low terminal residues of cyclosulfamuron in rice paddies suggest that no significant residues would be transported or carried over to the non-target environment.

• Korean Journal of Microbiology
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• v.43 no.1
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• pp.19-22
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• 2007

Acetohydroxyacid synthase (E.C.2.2.1.6., AHAS) is the enzyme that catalyses the first step in the synthesis of the branched-chain amino acids valine, leucine and isoleucine. The AHAS gene (TIGR access code HI2585) from Heamophilus influenzae was cloned into the bacterial expression vector pET-28a and expressed in the Escherichia coli strain BL21(DE3). The expressed enzyme was purified by $Ni^{2+}-charged$ HiTrap chelating HP column. The purified enzyme appears as a single band on SDS-PAGE with a molecular mass of about 63.9 kDa. The enzyme exhibits absolute dependence on the three cofactors FAD, $MgCl_{2}$ and thiamine diphosphate for activity. Specific activity of purified enzyme has 3.22 unit/mg and optimum activity in the pH 7.5 at $37^{\circ}C$. This enzyme activity has an effect on the buffer. When comparing the enzyme activity against the organic solvent, it followed in type and the difference it is but even from the aqueous solution where the organic solvent is included with the fact that the enzyme activity is maintained.

• The Korean Journal of Pesticide Science
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• v.14 no.4
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• pp.371-380
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• 2010

This study was performed to develop a precise single residue analytical method of fungicide cyprodinil in representative crops for using as general residue analytical methods which could be applied to most of crops. Apple, mandarin, Korean cabbage and green pepper were selected as representative crops, and they were macerated, extracted with acetonitrile, concentrated and partitioned with n-hexane. Then the extracts were concentrated and cleaned-up through silica gel column with ethyl acetate:n-hexane (15:85, v/v) before concentration and analysis with HPLC. LOQ (limit of quantitation) of cyprodinil was 5 ng (S/N>10) and MQL (method qnantitation limit) was 0.05 mg/kg. Recoveries were measured at three fortification levels (MQL, 10MQL and 100MQL) on crop samples and ranged from 82.0 to 108.2% and coefficients of variation were less than 10% regardless of sample type.

• The Korean Journal of Malacology
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• v.26 no.4
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• pp.267-273
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• 2010

From January to December 2007, we have investigated sediment types, environmental factors and density of clam Ruditapes philippinarum inhabited at Oeri, Naeri, Jonghyeon and Bangmiri tidal flats in Gyeonggi Bay off the west coast of Korea. Sediment types of Oeri and Jonghyeon were characterized with well sorted muddy sand. In contrast, Bangmiri tidal flat was mainly composed of poorly sorted gravelly muddy silt and Naeri was characterized with very poorly sorted muddy-sandy gravel. During the course of study, the surface water temperature, salinity, dissolved oxygen and pH ranged 3.2 to $27.0^{\circ}C$, 21.7 to 33.3 ‰, 5.6 to 12.7 mg/l and 7.36 to 8.82, respectively. The suspended solid (SS) ranged from 3.2 to 1,266.0 mg/l and chlorophyll-a level in the water column ranged $0.3-36.1{\mu}g/l$, respectively. The density of clam in the study areas was mainly determined by the harvesting activities rather than the types of substrate. Relatively higher density of clam was observed in Oeri and Bangmiri where the clam seeds were sowed by the villagers. Condition factor of clams were found to be higher in Oeri where the substrate sorting was better with higher level of chlorophyll a. It was believed that sediment types and the level of available food the two governing factors controlling the density and growth of clam in Gyeonggi Bay.

• Applied Biological Chemistry
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• v.9
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• pp.29-33
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• 1968

Through an experiment with gas chromatography carried out using diethylene glycol succinate(DEGS) as the packing material of the column, we have obtained the correction factor between the weight ratio and the peak dimension of the saturated fatty acid methyl esters of C10, C12, C14, C16, and C18 and unsaturated fatty acid methyl esters of oleic acid, linoloic acid, and linolenic acid, employing the detector of thermal conductivity type. Quantitative analysis of the fatty acids contained in rice Bran oil was performed with the above correction factor and the results are as follows; 1. Main components were found to be palmitic acid, oleic acid sand linolenic acid. No trases of capric acid (C10) lauric acid (C10) were found. 2. It was confirmed that there were straight line relation between the logarism retention time of each fatty acid and the number of carbon of saturated fatty acid or the number of double bond of other fatty acids having the same number of carbon. 3. The correction factor became larger as to the number of carbon increased up to C18 in case of saturated fatty acids, end as for other fatty acids, and as for other fatty acids of the same carbon number, it became larger according as the number of double bond increased.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.11
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• pp.1180-1185
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• 2005

Iron sand, having iron as a major component, was applied in the treatment of synthetic wastewater containing Cu(II) or Pb(II). To investigate the stability of iron sand at acidic condition, dissolution of Fe and Al was studied with variation of solution pH ranging from 2 to 4.5. Iron concentration in the extracted solution was below the emission regulation of wastewater even at a strong acidic condition, pH 2. Although an important concentration of aluminum was extracted at pH 2, the dissolution greatly decreased above pH 3. This stability test suggests that application of iron sand has little problem in the treatment of wastewater above pH 3. Adsorption capacity of Cu(II) and Pb(II) onto iron sand was investigated in a batch and a column test. In case of Cu(II), rapid adsorption was noted, showing 50% removal within 2 hrs, and then reached a near complete equilibrium after 24 hrs. Adsorption was favorable at higher pH in each metal ion and showed a near complete removal above pH 6, indicating a typical cationic-type adsorption. From the adsorption isotherm obtained with variation of the concentration of each metal ion, the maximum adsorption capacity of Cu(II) and Pb(II) was identified as 2,170 mg/kg 및 3,450 mg/kg, respectively.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.11
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• pp.747-754
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• 2017

The Concrete-Filled Tube (CFT) system was developed for its excellent structural performance, such as its good stiffness, stress and ductility, which is derived from the mechanical advantages of its composite structure. However, it is known that the flat type of reinforcing plates need stiffeners placed at a certain distance from each other to avoid buckling failure, which increases the cost accordingly. This paper investigates the contribution of the rib elements placed inside the steel tube for the purpose of increasing the bond strength between the steel and concrete and fire performance with no additional protection. The test results also demonstrate the effectiveness of the corrugated rib's shape against fire. The results of this study showed that the buckling prevention and fire resistance performance criteria were satisfied by the application of the inner surface attachment rib, due to the resulting increase in the strength of the CFT column. Therefore, it is considered that the CFT method using the corrugated rib structure reinforcement developed through this study satisfies the structural and fire resistance performance criteria without the need for a refractory coating. Future studies will be needed to make the process efficient and economical for factory production.

• The Korean Journal of Pesticide Science
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• v.13 no.4
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• pp.223-231
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• 2009

This study was performed to develop a precise single residue analytical method of fungicide fenhexamid in representative crops for general residue analytical method which could be applied to most of crops. Korean cabbage, mandarin, apple and green pepper were selected, macerated, extracted with acetone, concentrated and partitioned with dichloromethane. Then the extracts were concentrated and cleaned-up through Florisil column with ethyl acetate/0.1% acetic acid in hexane [15:85, (v/v)] before concentration and analysis with HPLC. LOQ (Limit of Quantitation) of fenhexamid was 1 ng (S/N>10) and MQL (Method Quantitative Limit) was 0.01 mg/kg. Recoveries were measured at two fortification levels (10 MQL and 50 MQL) on crop samples and ranged from 85.2% to 94.8% (mean recoveries) and coefficients of variation were <10% regardless of sample type.