• Journal of Life Science
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• v.20 no.8
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• pp.1201-1206
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• 2010

We performed a comparative analysis using a Real-time PCR (Polymerase Chain Reaction) and LC/MS (Liquid-Chromatograph/Mass Spectrometer) method in order to detect microcystin in environmental sources. Among the three different primer sets tested for microcystin using three positive strains of Microcystis aeruginosa by Real-time PCR assay, only TOX2P/TOX2M primer pairs were able to detect Microcystis aeruginosa. According to the results of a survey carried out from June 2009 to September 2009, 11 out of 11 (100%) raw water samples were were found to have microcystin when the Real-Time PCR and LC/MS method was used, with total microcystin concentration ranging from 5.98~219.0 ${\mu}g/l$. A microcystin removal treatment process was used to ensure entire removal, by passing it through a BAC filtration step. It was concluded that real-time PCR assay can be used to estimate micrucystin detection more rapidly and easily than the LC/MS method.

• The Korean Journal of Pesticide Science
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• v.2 no.3
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• pp.79-84
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• 1998

Tandem HPLC and atmospheric pressure chemical ionization(APcI) LC/MS method was used for the determination and confirmation of carbendazim residues in soybean sprout. Fluorescence(FL) detector was connected in tandem with the ultraviolet(UV) detector for dual detection of the carbendazim residue at the excitation and emission wavelength of 280 nm and 310 nm, respectively. The limit of detection for carbendazim was $0.1{\mu}g/kg$ sample. Recoveries of carbendazim from fortified soybean sprout at 0.5, 1.0 and 2.0 ppm were averaged 89.1%. Mass spectrometry using a APcI source confirmed the carbendazim residue in the soybean sprout sample. Fragmentation pattern on the APcI LC/MS spectrum of carbendazim was simpler than that from electron impact(EI) mass spectrum. Carbendazim produced 3 major ions including m/z 133, m/z 159 and m/z 191($M^{+}$). This method was sensitive enough to provide reliable and reproducible results for practical applications.

• The Journal of Korean Obstetrics and Gynecology
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• v.26 no.4
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• pp.48-65
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• 2013

Objectives: We took breast milk samples and analyzed them using HPLC and LC/MS/MS, to evaluate the effects of taking Saenghwa-tang during breastfeeding on breast milk. Methods: The study participants were 20 lactating women who admitted in Korean medical postpartum care center. Breast milks were collected from paticipants who have been administrated Saenghwa-tang for more than 3 days. We used HPLC and LC/MS/MS for the determinations of amygdalin, liquiritins, 6-gingerol, decursin and decursinol angelate in Saenghwa-tang. Results: 1. Participants' $Mean{\pm}S.D$ (standard deviation) of age is $31.05{\pm}1.96$, and 15 participants had normal delivery and 5 participants had cesarean delivery. 12 participants were primipara and 8 participants were multipara. $Mean{\pm}S.D$ of lactating date is $9.4{\pm}0.94$. 2. Using HPLC, we learned LOQ level peak that matches the peak retention time of standard components of Saenghwa-tang was not detected from 20 breast milk samples. 3. Using LC/MS/MS, decursin of Angelicae Gigantis Radix was detected from HMSP 02, HMSP 04, HMSP 06, HMSP 11, and the each concentrations are 16, 2, 64, 11 ppb. Liquiritin of Glycyrrhizae Radix was not detected from HMSP 13~HMSP 18. Conclusions: Data obtained by this approach shows that this method is reliable and suitable for determining the safety of taking Saenghwa-tang during breastfeeding.

• Journal of Educational Research in Mathematics
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• v.14 no.3
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• pp.239-266
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• 2004

This article presents new perspectives for analysing and diagnosing students' mathematical errors on the basis of Pascaul-Leone's neo-Piagetian theory. Although Pascaul-Leone's theory is a cognitive developmental theory, its psychological mechanism gives us new insights on mathematical errors. We analyze mathematical errors in the domain of proof problem solving comparing Pascaul-Leone's psychological mechanism with mathematical errors and diagnose misleading factors using Schoenfeld's levels of analysis and structure and fuzzy cognitive map(FCM). FCM can present with cause and effect among preconceptions or misconceptions that students have about prerequisite proof knowledge and problem solving. Conclusions could be summarized as follows: 1) Students' mathematical errors on proof problem solving and LC learning structures have the same nature. 2) Structures in items of students' mathematical errors and misleading factor structures in cognitive tasks affect mental processes with the same activation mechanism. 3) LC learning structures were activated preferentially in knowledge structures by F operator. With the same activation mechanism, the process students' mathematical errors were activated firstly among conceptions could be explained.

• Journal of Korean Tunnelling and Underground Space Association
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• v.21 no.6
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• pp.875-885
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• 2019

This paper is aimed to suggest the coefficient of variation of the total load on the segment lining and the coefficient of variation of earth pressure in reliability based design of shield tunnel. For this purpose, the statistical characteristics of weathered soil and weathered rock were calculated by analyzing the site survey data of the domestic urban section. The coefficient of variation could be estimated by applying these values to Terzaghi's theory using MCS technique. As a result, the coefficient of variation of rock load for weathered soil and weathered rock was 0.08~0.14. The coefficient of variation for the total load acting on the tunnel was LC1 = 0.38, LC2 = 0.33, and LC3 = 0.37. The proposed coefficients of variation can be used in the reliability-based design of shield tunnel segments.

• Journal of Microbiology and Biotechnology
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• v.29 no.7
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• pp.1155-1164
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• 2019

Lichens contain diverse bioactive secondary metabolites with various chemical and biological properties, which have been widely studied. However, details of the inhibitory mechanisms of their secondary metabolites against influenza A virus (IAV) have not been documented. Here, we investigated the antiviral effect of lichen extracts, obtained from South Korea, against IAV in MDCK cells. Of the lichens tested, Nipponoparmelia laevior (LC24) exhibited the most potent inhibitory effect against IAV infection. LC24 extract significantly increased cell viability, and reduced apoptosis in IAV-infected cells. The LC24 extract also markedly reduced (~ 3.2 log-fold) IAV mRNA expression after 48 h of infection. To understand the antiviral mechanism of LC24 against IAV, proteomic (UPLC-$HDMS^E$) analysis was performed to compare proteome modulation in IAV-infected (V) vs. mock (M) and LC24+IAV (LCV) vs. V cells. Based on Ingenuity Pathway Analysis (IPA), LC24 inhibited IAV infection by modulating several antiviral-related genes and proteins (HSPA4, HSPA5, HSPA8, ANXA1, ANXA2, $HIF-1{\alpha}$, AKT1, MX1, HNRNPH1, HNRNPDL, PDIA3, and VCP) via different signaling pathways, including $HIF-1{\alpha}$ signaling, unfolded protein response, and interferon signaling. These molecules were identified as the specific biomarkers for controlling IAV in vitro and further confirmation of their potential against IAV in vivo is required. Our findings provide a platform for further studies on the application of lichen extracts against IAV.

• Annals of Hepato-Biliary-Pancreatic Surgery
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• v.26 no.2
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• pp.159-167
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• 2022

Backgrounds/Aims: The optimal timing of percutaneous transhepatic gallbladder drainage (PTGBD) and subsequent laparoscopic cholecystectomy (LC) according to the severity of acute cholecystitis (AC) has not been established yet. Methods: This single-center, retrospective study included 695 patients with grade I or II AC without common bile duct stones who underwent PTGBD and subsequent LC between January 2010 and December 2019. Difficult surgery (DS) (open conversion, subtotal cholecystectomy, adjacent organ injury, transfusion, operation time ≥ 90 minutes, or estimated blood loss ≥ 100 mL) and poor postoperative outcome (PPO) (postoperative hospital stay ≥ 7 days or Clavien-Dindo grade ≥ II postoperative complication) were defined to comprehensively evaluate intraoperative and postoperative outcomes, respectively. Results: Of 695 patients, 403 had grade I AC and 292 had grade II AC. According to the receiver operating characteristic curve and multivariate logistic regression analyses, an interval from symptom onset to PTGBD of > 3.5 days and an interval from PTGBD to LC of > 7.5 days were significant predictors of DS and PPO, respectively, in grade I AC. In grade II AC, the timing of PTGBD and subsequent LC were not statistically related to DS or PPO. Conclusions: In grade I AC, performing PTGBD within 3.5 days after symptom onset can reduce surgical difficulties and subsequently performing LC within 7.5 days after PTGBD can improve postoperative outcomes. In grade II AC, early PTGBD cannot improve the surgical difficulty. In addition, the timing of subsequent LC is not correlated with surgical difficulties or postoperative outcomes.

• Bulletin of the Korean Chemical Society
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• v.33 no.11
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• pp.3727-3734
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• 2012

An analytical method has been developed for the rapid determination of perfluorinated compounds (PFCs) in human serum samples. The extraction and purification of PFCs from human serum were performed by the modified method of previous report. Ten PFCs were rapidly separated within 3.3 min by C18-monolithic column liquid chromatography (LC) and detected by electrospray ionization (ESI) tandem mass spectrometry (MS/MS) in negative ion mode. The runtime of PFCs on monolithic column LC was up to 4-fold faster than that on conventional column LC. The effect of triethylamine (TEA) to the mobile phase has investigated on the overall MS detection sensitivity of PFCs in ESI ionization. Quantification was performed by LC-MS/MS in multiple-ion reaction monitoring (MRM) mode, using $^{13}C$-labeled internal standards. Method validation was performed to determine recovery, linearity, precision, and limits of quantification, followed by, the analysis of a standard reference material (SRM 1957 from NIST). The overall recoveries ranged between 81.5 and 106.3% with RSDs of 3.4 to 16.2% for the entire procedure. The calibration range extended from 0.33 to 50 $ng\;mL^{-1}$, with a correlation coefficient ($R^2$) greater than 0.995 and the limits of quantification with 0.08 to 0.46 $ng\;mL^{-1}$. This approach can be used for rapid and sensitive quantitative analysis of 10 PFCs in human serum with high performance and accuracy.

• Korean Journal of Veterinary Service
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• v.42 no.3
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• pp.127-133
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• 2019

The purpose of this study was to investigate the contamination level of representative mycotoxins that have adverse effects on livestock by using LC-MS/MS method and to utilize the results as basic data for the establishment of quality control system for feed, and to provide information on production and storage. A total of nine mycotoxins, including aflatoxin $B_1$, aflatoxin $B_2$, aflatoxin $G_1$, aflatoxin $G_2$, ochratoxin A, fumonisin $B_1$, fumonisin $B_2$, deoxynivalenol (DON), zearalenone (ZEN) were simultaneously analyzed in LC-MS/MS under ESI positive mode. Fumonisin $B_1$ and fumonisin $B_2$ were detected from 3 cases of 75 forage produced in Incheon area, the detection rate was 4.0%. The detection concentration was 0.01~0.02 mg/kg, which was lower than the domestic recommended limit. Fumonisins were detected in a slightly different manner from the results of mycotoxin studies reported in Korea, which is attributed to the high temperature and dry summer weather of the year. The result of LC-MS/MS method performance of 9 mycotoxins, the recovery of DON was quite low as $41.53{\pm}3.91%$ that is not suitable for simultaneous analysis. This is probably due to that the extract solution used in this study was not suitable for the extraction of DON, along with the characteristics of a very dry forage. For the study of mycotoxins in Incheon area forage for the first time, further investigation is needed for the safe supply of livestock products.

• Restorative Dentistry and Endodontics
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• v.24 no.2
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• pp.416-425
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• 1999

The purpose of this study was to evaluate shear bond strength of glass ionomer cements and compomer according to dentin surface treatment method. The materials used in this study were dentin conditioner and cavity conditioner for dentin treatment: Ketacfil, Fuji II LC, and Dyract for restoration. In this study, 90 sound bovine teeth were selected and then the teeth were embeded in improved stone and were grounded with 400 to 600 grit silicon carbide paper to create a flat dentin surfaces. The teeth were divided into nine groups as follows ; Group 1A : Samples bonded to dentin surface with Ketacfil after no treatment Group 1B : Samples bonded to dentin surface with Ketacfil after applicating dentin conditioner Group 1C : Samples bonded to dentin surface with Ketacfil after applicating cavity conditioner Group 2A : Samples bonded to dentin surface with Fuji II LC after no treatment Group 2B : Samples bonded to dentin surface with Fuji II LC after applicating dentin conditioner Group 2C : Samples bonded to dentin surface with Fuji II LC after applicating cavity conditioner Group 3A : Samples bonded to dentin surface with Dyract after no treatment Group 3B : Samples bonded to dentin surface with Dyract after applicating dentin conditioner Group 3C : Samples bonded to dentin surface with Dyract after applicating cavity conditioner Treated dentin surfaces were observed under SEM. After filling of each materials, shear bond strenth was evaluated and then debonded surfaces were observed under SEM. The following results were obtained; 1. The shear bond strengths obtained were decreased as Fuji II LC, Dyract, Ketacfil in that order and there was statistically significant difference(p<0.05). 2. About Group 1. the shear bond strengths were decreased as 1C, 1B and 1A in that order. But there was no significant difference between group 1B and 1C (p<0.05). 3. About Group 2, the shear bond strengths were decreased as group 2B, 2A and 2C in that order. And there was significant difference between group 2B and 2C (p<0.05). 4. About Group 3, the shear bond strengths were decreased as group 3A, 3C and 3B in that order. And there was signicant difference between group 3A and 3B (p<0.05). 5. As a result of observation under SEM, the fracture patterns of Fuji II LC and Dyract were adhesive failures, but those of Ketacfil were cohesive failure of material and mixture of cohesive and adhesive failure.