• Journal of The Korean Astronomical Society
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• v.52 no.3
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• pp.57-69
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• 2019

We present an analysis of the chemical abundances and kinematics of six low-mass dwarf stars, previously claimed to be candidate hypervelocity stars (HVSs). We obtained moderate-resolution (R ~ 6000) spectra of these stars to estimate the abundances of several chemical elements (Mg, Si, Ca, Ti, Cr, Fe, and Ni), and derived their space velocities and orbital parameters using proper motions from the Gaia Data Release 2. All six stars are shown to be bound to the Milky Way, and in fact are not even considered high-velocity stars with respect to the Galactic rest frame. Nevertheless, we attempt to characterize their parent Galactic stellar components by simultaneously comparing their element abundance patterns and orbital parameters with those expected from various Galactic stellar components. We find that two of our program stars are typical disk stars. For four stars, even though their kinematic probabilistic membership assignment suggests membership in the Galactic disk, based on their distinct orbital properties and chemical characteristics, we cannot rule out exotic origins as follows. Two stars may be runaway stars from the Galactic disk. One star has possibly been accreted from a disrupted dwarf galaxy or dynamically heated from a birthplace in the Galactic bulge. The last object may be either a runaway disk star or has been dynamically heated. Spectroscopic follow-up observations with higher resolution for these curious objects will provide a better understanding of their origin.

• Journal of Technologic Dentistry
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• v.43 no.4
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• pp.168-174
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• 2021

Purpose: This study was conducted to investigate alloys spectrophotometrically including yttrium of nickel-chromium (Ni-Cr) alloys, which are used as substitutes for the regulation of beryllium and provide helpful improvements in Ni-Cr alloys. Methods: Four groups of specimens (ZN, ZY, SN and EM) were prepared for analysis. Color parameters were measured with a spectrophotometer, and color difference (∆E^*) was calculated. The t-test and one-way analysis of variance test were used to determine significant difference, and the Tukey test was used to identify where the differences were. To measure the spectroscopic reflectivity, the spectroscopic reflectance was measured and converted into CIE L^*, a^*, b^* color system. Results: The ∆E^* value of each metal ceramic group after opaque firing of Ni-Cr alloy with and without yttrium was <2, and the total group color difference (∆E^*) was below 1 in the dentin ceramic all experimental group. However, the a^* and b^* values of the metal ceramic groups were higher than that in the lithium disilicate all ceramic group, and the chroma was higher than the natural tooth. The brightness of all experimental groups was similar to that of the shade guide sample. Conclusion: Yttrium added to Ni-Cr alloys showed similar CIE L^*, a^*, b^* values to Ni-Cr alloys that did not contain yttrium, indicating that yttrium had no effect on color in metallic ceramic systems.

• Journal of Ginseng Research
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• v.48 no.4
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• pp.395-404
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• 2024

Background: Ginsenoside Rg₁ (Rg₁) is one of the main active components in Chinese medicines, Panax ginseng and Panax notoginseng. Research has shown that Rg₁ has a protective effect on the cardiovascular system, including anti-myocardial ischemia-reperfusion injury, anti-apoptosis, and promotion of myocardial angiogenesis, suggesting it a potential cardiovascular agent. However, the protective mechanism involved is still not fully understood. Methods: Based on network pharmacology, ligand-based protein docking, proteomics, Western blot, protein recombination and spectroscopic analysis (UV-Vis and fluorescence spectra) techniques, potential targets and pathways for Rg₁ against myocardial ischemia (MI) were screened and explored. Results: An important target set containing 19 proteins was constructed. Two target proteins with more favorable binding activity for Rg₁ against MI were further identified by molecular docking, including mitogen-activated protein kinase 1 (MAPK1) and adenosine kinase (ADK). Meanwhile, Rg₁ intervention on H9c2 cells injured by H₂O₂ showed an inhibitory oxidative phosphorylation (OXPHOS) pathway. The inhibition of Rg₁ on MAPK1 and OXPHOS pathway was confirmed by Western blot assay. By protein recombination and spectroscopic analysis, the binding reaction between ADK and Rg₁ was also evaluated. Conclusion: Rg₁ can effectively alleviate cardiomyocytes oxidative stress injury via targeting MAPK1 and ADK, and inhibiting oxidative phosphorylation (OXPHOS) pathway. The present study provides scientific basis for the clinical application of the natural active ingredient, Rg₁, and also gives rise to a methodological reference to the searching of action targets and pathways of other natural active ingredients.

• Korean Journal of Pharmacognosy
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• v.25 no.3
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• pp.214-220
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• 1994

From the Viticis Fructus n-hydrocarbons, ${\beta}-sitosterol$ $3-O-{\beta}-_D-glucoside$ and hesperidin along with the known polyoxygenated flavonoids such as vitexicarpin, artemetin and luteolin, and vanillic acid were isolated and identified by means of spectroscopic methods. HPLC analysis of the flavonoid components from the MeOH extract was established. Phytochemical analyses of the domestic plant sample and the imported ones were conducted and the flavonoid compositions of the domestic samples were greatly different from those of the imported ones.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.45 no.1
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• pp.27-34
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• 2013

Quantitative analysis of 5-hydroxymethylfufural (5-HMF) conversion from fructose by dehydration and rearrangement was investigated by $^1H$-NMR spectroscopic method. Fructose was converted to 5-HMF in dimethylsulfoxide (DMSO)-$d^6$ or acidic deuterium hydroxide at controlled reaction temperature and time. With addition of internal standards (biphenyl for DMSO-$d^6$ solvent, and 2,5-dihydroxybenzoic acid for deuterium oxide solvent), conversion from fructose to 5-HMF was analyzed by $^1H$-NMR spectroscopy. Quantitative analysis was run by comparison with peak area integration between of 5-HMF and internal standard. In DMSO solvent, 5-HMF was stable end product but part of 5-HMF was converted to formic and levulinic acid at acidic aqueous medium.

• Korean Journal of Pharmacognosy
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• v.32 no.1 s.124
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• pp.43-48
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• 2001

Epimedii Herba has been used for tonic, cardiotonic, impotency, amnestic and diuretic. Icariin, a main component was isolated from the Epimedii Herba and identified by the spectroscopic methods. In order to evaluate the quality of Epimedii Herba purchased from various regions of Korea, quantitative determination of icariin in Epimedii Herba using HPLC method has been conducted. Quantitative analysis showed the average amount of icariin in commercial 42 samples was 0.34% on the dry weight basis.

• Journal of the Korean Ceramic Society
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• v.54 no.1
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• pp.28-32
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• 2017

The degradation of methyl blue (MB) catalyzed by platinum (Pt)-graphene/$TiO_2$ in dark ambiance was studied. Pt-graphene/$TiO_2$ composites were prepared by simple hydrothermal method. Characterizations of composites were studied by X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), specific surface area (BET) analysis, and energy dispersive X-ray (EDX) analysis. UV-spectroscopic analysis of the dyes was performed by measuring the change in absorbance. The degradation of the organic dyes was calculated based on the decrease in concentration of the dyes with respect to regular time intervals. Rate coefficients for the catalytic process were successfully established and reusability tests were performed to test the stability of the used catalysts.

• Korean Journal of Pharmacognosy
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• v.33 no.4 s.131
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• pp.277-284
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• 2002

For the quality control of Kalopanacis Cortex, saponin compound, kalopanax-saponin B was isolated from the MeOH extract of Kalopanacis Cortex, and identified by the spectroscopic evidences. A quantitative analysis of kalopanaxsapo-nits B using HPLC method showed that the average contents was $1.010{\pm}0.212%$, respectively, in 22 samples collected through-out the regions of Korea.

• Korean Journal of Pharmacognosy
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• v.33 no.4 s.131
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• pp.272-276
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• 2002

This study was carried out to establish the quantitative analysis of lignans for the quality evaluation of fruit from Schizandra chinensis. Five lignans, gomisin N, schizandrin, gomisin C, schisantherin C, and gomisin A were isolated from the fruits of S. chinensis and identified by the spectroscopic methods. Quantitative determination of three lignans, schizandrin, gomisin A, gomisin N, was conducted using HPLC. Average contents of three lignans in collected lines were 0.70% of schizandrin, 0.20% of gomisin A, 0.57% of gomisin N, and 1.47% of total lignans.

• Korean Journal of Pharmacognosy
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• v.33 no.2 s.129
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• pp.100-104
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• 2002

Sanguisorbae Radix has hemostatic, analgesic and astrigent properties and it has been used for the treatment of burns, scalds and internal hemorrhage. Ziyuglycoside I was isolated from Sanguisorbae Radix and identified by the spectroscopic methods. In order to evaluate the quality of it, quantitative determination of Ziyuglycoside I in Sanguisorbae Radix using HPLC method has been conducted. Quantitative analysis of Ziyuglycoside I showed average 3.005% in 30 samples collected throughout the regions of Korea.