• Journal of the Korean Society of Manufacturing Process Engineers
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• v.20 no.10
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• pp.72-79
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• 2021

A circular saw is an effective tool for cutting glass and carbon-fiber hybrid composites. This study investigated tool wear and cut quality when reusing saw blades. The carbide saws wear four times faster than the new ones, and polycrystalline diamond (PCD) is very resistant to tool wear, except at the end of its lifespan. The cut cross-section quality is affected by the blade type, tool wear, and spindle speed. Alternate top bevel (ATB)-type blades are suitable for cutting fiber-reinforced plastics, but triple-chip grind (TCG)-type blades are unsuitable because they cause fiber-pullout defects. Tool wear and low spindle speeds increase the occurrence of arc scratches, due to the rear saw blade. A microscopic examination showed that the burr, which is a mixture of fiber chips and epoxy matrix, was bonded on top, and glass-fiber delamination occurred on the bottom glass-fiber-reinforced polymer (GFRP) surface.

• Biomedical Science Letters
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• v.27 no.3
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• pp.134-141
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• 2021

c-Jun N-terminal kinases (JNKs) have a Janus face, regulating both cell apoptosis and survival. The present study focused on understanding the function of JNK in tumor development and the chemoresistance underlying JNK-mediated cancer cell survival. We identified an inhibitor of JNK1, an important regulator of cancer cell survival. Kinase assay data showed that JNK1-dependent c-Jun phosphorylation was inhibited by indirubin derivatives. In particular, indirubin-3-monoxime (I3M) directly inhibited the phosphorylation of c-Jun in vitro, with a half inhibition dose (IC₅₀) of 10 nM. I3M had a significant inhibitory effect on JNK1 activity. Furthermore, we carried out assays to determine the viability, migration, and proliferation of breast cancer cells. Our results demonstrated that cell growth, scratched wound healing, and colony forming abilities were inhibited by the JNK inhibitor SP600125 and I3M. The combination of SP600125 and I3M significantly decreased cancer cell proliferation, compared with either SP600125 or I3M alone. Our studies may provide further support for JNK1-targeting cancer therapy using the indirubin derivative I3M in breast cancer.

• Mass Spectrometry Letters
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• v.9 no.4
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• pp.95-99
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• 2018

An innovative, simple, and rapid assay method based on liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) was developed and validated for the simultaneous determination of eight statin drugs in human urine. A simple sample clean-up procedure using the "dilute and shoot" (DAS) approach enabled a fast and reliable analysis. The influence of the dilution factor was investigated to ensure detectability and reduce the matrix effect. Chromatographic separation was performed on a Phenomenex Kinetex C18 column ($50{\times}3.0mm$ i.d., $2.6{\mu}m$) using an elution gradient of mobile phase A composed of 0.1% acetic acid, and mobile phase B composed of acetonitrile, at a flow rate of 0.35 mL/min. Quantitation was performed on a triple quadrupole mass spectrometer operated in multiple reaction monitoring (MRM) mode using electrospray ionization in positive ion mode. The total chromatographic run time was 15 min. The method was validated for selectivity, sensitivity, recovery, linearity, accuracy, precision, and stability. The present method was successfully applied to the analysis of Rosuvastatin in urine samples after oral administration to healthy human subjects.

• Natural Product Sciences
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• v.25 no.1
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• pp.16-22
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• 2019

Inula helenium L. is rich source of eudesmane-type sesquiterpene lactones, mainly alantolactone and isoalantolactone, which have the various pharmacological functions. In this study, we examined the inhibitory effects of nitric oxide (NO) production of hexane, methylene chloride, ethyl acetate, butanol, and water fractions from I. helenium and investigated the anti-inflammatory effect of hexane fraction of I. helenium (HFIH) in LPS-induced RAW 264.7 cells. Quantification of alantolactone and isoalantolactone from HFIH was carried out for the standardization by multiple reaction monitoring using triple quadrupole mass spectrometer. HFIH significantly inhibited inducible NO synthase (iNOS) and cyclooxygenase-2 (COX-2) protein as well as their downstream products NO and prostaglandin $E_2$ ($PGE_2$) in LPS-stimulated RAW 264.7 cells. Moreover, HFIH suppressed $NF-{\kappa}B$ transcriptional activity by decreasing the translocation of p65 to the nucleus. The in vivo study further confirmed that HFIH attenuated the paw edema induced by carrageenan in an acute inflammation model. These findings suggest that HFIH may be useful as a promising phytomedicine for inflammatory-associated diseases.

• Mass Spectrometry Letters
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• v.11 no.4
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• pp.82-89
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• 2020

A systematic isolation and characterization study for Cassia auriculata (CA) seeds resulted in identifying antidiabetic compounds 1,3,8-trihydroxyanthraquinone and quercetin, quercetin-3-O-rutinoside, gallic acid, caffeic acid, ferulic acid, and ellagic acid. The ultra-high-performance liquid chromatography based triple quadrupole mass spectrometry methodology was developed and validated for simultaneous identification and confirmation of these compounds from CA seeds. Multiple reaction monitoring (MRM) based quantification method was developed with MRM optimizer software for MS1 and MS2 mass analysis. The method was optimized on precursor ions and product ions with the ion ratio of each compound. The calibration curves of seven bioactive analytes showed excellent linearity (r2 ≥ 0.99). The quantitation results found precise (RSD, < 10 %) with good recoveries (84.58 to 101.42%). The matrix effect and extraction recoveries were found within the range (91.66 to 102.11%) for the CA seeds. This is the first MS/MS-based methodology applied to quantifying seven antidiabetic compounds in CA seeds and its extract for quality control purposes.

• Earthquakes and Structures
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• v.23 no.1
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• pp.87-100
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• 2022

Limiting the displacement of seismic isolators causes a pounding phenomenon under severe earthquakes. Therefore, the ASCE 7-16 has provided minimum criteria for the design of the isolated building. In this research the seismic response of isolated buildings by Triple Friction Pendulum Isolator (TFPI) under the impact, expected, and unexpected mass eccentricity was evaluated. Also, the effect of different design parameters on the seismic behavior of structural and nonstructural elements was found. For this, a special steel moment frame structure with a surrounding moat wall was designed according to the criteria, by considering different response modification coefficients (RI), and 20% mass eccentricity in one direction. Then, different values of these parameters and the damping of the base isolation were evaluated. The results show that the structural elements have acceptable behavior after impact, but the nonstructural components are placed in a moderate damage range after impact and the used improved methods could not ameliorate the level of damage. The reduction in the RI and the enhancement of the isolator's damping are beneficial up to a certain point for improving the seismic response after impact. The moat wall reduces torque and maximum absolute acceleration (MAA) due to unexpected enhancement of mass eccentricity. However, drifts of some stories increase. Also, the difference between the response of story drift by expected and unexpected mass eccentricity is less. This indicates that the minimum requirement displacement according to ASCE 7-16 criteria lead to acceptable results under the unexpected enhancement of mass eccentricity.

• Advances in Computational Design
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• v.8 no.4
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• pp.273-293
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• 2023

This study evaluated the acoustic performance of two configurations of serial HR arrays and lined HR arrays in the presence of grazing flow using a 3D numerical simulation. The dual, triple, and quad HR arrays were compared to the conventional HR array. The simulation results showed that the number of resonant frequencies increased with the number of serial HR arrays. The C_TL did not significantly change with the number of serial HR arrays. The acoustic performance of the two, three, and four-lined HR arrays was compared to the conventional HR array. The results showed that the resonant frequency and TLmax increased with the number of lined HR arrays. The C_TL also increased with the number of lined HR arrays. The effect of the grazing flow Mach number (M_a) was investigated on the four-lined HR array configuration and compared to the conventional HR configuration. TLmax and C_TL decreased for both configurations with increasing M_a. The four-lined HR array configuration had significantly better acoustic performance than the conventional HR configuration. The TLmax and C_TL increased by more than 300% when the configuration was changed from the conventional HR to the four-lined HR array at M_a = 0.The increment percentage decreased with increasing M_a.

• Microbiology and Biotechnology Letters
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• v.51 no.4
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• pp.507-516
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• 2023

Eradication of Helicobacter pylori infection is an essential strategy to decrease the risk of developing gastric cancer. However, the standard triple therapy has negative aspects associated with side effects and the emergence of antibiotic resistance. Therefore, alternative therapies are required to enhance the management of H. pylori infection effectively. In this study we examined the effect of emodin on the amelioration of inflammatory response due to H. pylori infection. Our results indicated that emodin treatment effectively decreased the expression of virulence genes, including sabA, vacA, cagL, cagA, sabA, and suppressed the adhesion ability of H. pylori to AGS cells. Emodin has been shown inhibitory effects on the inflammasome pathway through reductions in VacA translocation, lowering ROS stress, cleaved Caspase-1, NLRP3, and cleaved Gasdermin D levels, thereby lowered pyroptosis in infected cells. In summary, our study demonstrated that emodin has the ability to attenuate inflammation caused by H. pylori by modulating virulence gene expression and decreasing VacA translocation. Further study is required to evaluate the therapeutic efficacy of emodin in treating H. pylori infection and better understand the underlying mechanisms.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.34 no.4
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• pp.409-416
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• 2010

The use of oxy-fuel combustion and flue gas recirculation (FGR) for $CO_2$ reduction has been studied by many researchers. This study focused on the characteristics of oxy-fuel combustion and the effects of $CO_2$ addition from the point of view of oxygen feeding ratio (OFR) and the position of $CO_2$ addition in order to reproduce an FGR system with a triple concentric multi-jet burner. Oxy-fuel combustion was stable at all OFRs at a fuel flow-rate of 15 lpm, which corresponds to an equivalence ratio of 0.93; however, the structure and length of the flame varied at different OFRs. When $CO_2$ was added in oxy-fuel combustion, various stability modes such as stable, transient, quasistable, unstable, and blow-out were observed. The temperature in the combustion chamber decreased upon $CO_2$ addition in all conditions, and the maximum reduction in temperature was below 1800 K. $CO_2$ concentration with respect to height varied with the volume percent of $CO_2$ at the nozzle tip.

• Journal of the Korean Chemical Society
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• v.40 no.8
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• pp.557-564
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• 1996

FAB CAD MS/MS(Fast Atom Bombardment Collision Activated Dissociation Mass Spectrometry/Mass Spectrometry) was used to study different degree of bond stability according to the linkage positions of alkali cationized $(Na^+, Li^+, K^+, NH_4^+)$ stereoisomeric and synthetic oligosaccharides. The alkali metal cations were much more stable, requiring over -40 eV of collision energy vs. only -10 eV for the protonated forms. Of the cations, the potassium cationized trisaccharides were more stable than the others. They would not yield fragment ions under the conditions of collision available in triple quadrupole. Other cationized species exhibited decreasing stability in the series $Nap^+>Li^+>NH_4^+$ using 0.8 mTorr argon pressure in the collision cell. Metal cations of the oligosaccharides maintained charge principally on the amino sugar as shown by shift of all the fragment ions containing the amino sugar. The reason for the higher stability of the metal cationized form is the formation of crown ether-like bond around metal cations, N-acetyl group on GlcNAc and oxygens on fucose moiety. Depending on the metal sizes and the conformation of linkage-isomeric region, cationized species gave linkage dependent fragment patterns and exhibited stability in the series 1-6 > 1-4 > 1-3 linkage.