• Journal of Electrochemical Science and Technology
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• v.14 no.1
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• pp.96-104
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• 2023

Synergistically increased oxygen evolution reaction (OER) of manganese oxide (MnO₂) catalyst is introduced with surface-modified halloysite nanotube (Fe₃O₄-HNTs) structure. The flake shaped MnO₂ catalyst is attached on the nanotube template (Fe₃O₄-HNTs) by series of wet chemical and hydrothermal method. The strong interaction between MnO₂ and Fe₃O₄-HNTs maximized active surface area and inter-connectivity for festinate charge transfer reaction for OER. The synergistical effect between Fe₃O₄ layer and MnO₂ catalyst enhance the Mn³⁺/Mn⁴⁺ ratio by partial replacement of Mn ions with Fe. The relatively increased Mn³⁺/Mn⁴⁺ ratio on MnO₂@FHNTs induced 𝜎^* orbital (e_g) occupation close to single electron, improving the OER performances. The MnO₂@FHNTs catalyst exhibited the reduced overpotential of 0.42 V (E vs. RHE) at 10 mA/cm² and Tafel slope of (99 mV/dec), compared with that of MnO₂ with unmodified HNTs (0.65 V, 219 mV/dec) and pristine MnO₂ (0.53 V, 205 mV/dec). The present study provides simple and innovative method to fabricate nano fiberized OER catalyst for a broad application of energy conversion and storage systems.

• Journal of Electrochemical Science and Technology
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• v.14 no.2
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• pp.162-173
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• 2023

Aqueous zinc-ion batteries are considered as promising alternatives to lithium-ion batteries for energy storage owing to their safety and cost efficiency. However, their lifespan is limited by the irreversibility of Zn anodes because of Zn dendrite growth and side reactions such as the hydrogen evolution reaction and corrosion during cycling. Herein, we present a strategy to restrict direct contact between the Zn anode and aqueous electrolyte by fabricating a protective layer on the surface of Zn foil via phosphidation method. The Zn₃(PO₄)₂ protective layer effectively suppresses Zn dendrite growth and side reactions in aqueous electrolytes. The electrochemical properties of the Zn₃(PO₄)₂@Zn anode, such as the overpotential, linear polarization resistance, and hydrogen generation reaction, indicate that the protective layer can suppress interfacial corrosion and improve the electrochemical stability compared to that of bare Zn by preventing direct contact between the electrolyte and the active sites of Zn. Remarkably, MnO₂ Zn₃(PO₄)₂@Zn exhibited enhanced reversibility owing to the formation a stable porous layer, which effectively inhibited vertical dendrite growth by inducing the uniform plating of Zn²⁺ ions underneath the formed layer.

• The Bulletin of The Korean Astronomical Society
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• v.46 no.1
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• pp.44.2-45
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• 2021

As implied by the zodiacal light and spacecraft impact measurements, the space between large bodies in our Solar System is filled with interplanetary dust particles (IDPs). IDPs give us deeper insight into the composition and evolution of the Solar System, as well as being a crucial reference for extrasolar research. IDPs can be interpreted as bearers of carbon and organic materials, and thus, their interaction with Earth can be considered as important factors for the birth of terrestrial life. One of the key routes of IDPs entering Earth is via meteoroid streams (Love and Brownlee 1993). The Geminid meteoroid stream is a notable example. Together with its source asteroid (3200) Phaethon, the Phaethon-Geminid stream complex (PGC) (Whipple 1983; Gustafson 1989) can potentially provide information on the properties and evolution of IDPs in near-Earth space. DESTINY+* is a JAXA/ISAS spacecraft planned to launch in 2024 to explore the physical and chemical features of near-Earth IDPs and uncover the dust ejection mechanism of active near-Earth asteroids, especially Phaethon (Arai et al. 2018). Previous studies on the dust ejection mechanism of Phaethon have various degrees of success in explaining the ejection of submillimeter particles and try to recreate the dust replenishment rate of the Geminid stream. However, none of them are satisfactory for explaining the observed Geminid stream, especially for larger particles of a millimeter and centimeter scales. Inspired by the discovery of rotational mass shedding in the Main Belt region (Jewitt et al., 2014), we investigate a dust ejection scenario by rotational instability on Phaethon. Using the N-body integrator MERCURY6 (Chambers 1999; modified by Jeong 2014), we performed a long-term integration of dust particles of various sizes ejected at ~1 m/s. Through this process, we discuss the implications Phaethon's rotation may have on its ejection, the formation and evolution of IDP by this mechanism, and contribute to the DESTINY+ mission.

• The Bulletin of The Korean Astronomical Society
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• v.45 no.1
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• pp.38.2-38.2
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• 2020

Horizon Run 5 (HR5) is a cosmological hydrodynamical simulation which captures the properties of the Universe on a Gpc scale while achieving a resolution of 1 kpc. This enormous dynamic range allows us to simultaneously capture the physics of the cosmic web on very large scales and account for the formation and evolution of dwarf galaxies on much smaller scales. Inside the simulation box. we zoom-in on a high-resolution cuboid region with a volume of 1049 × 114 × 114 Mpc3. The subgrid physics chosen to model galaxy formation includes radiative heating/cooling, reionization, star formation, supernova feedback, chemical evolution tracking the enrichment of oxygen and iron, the growth of supermassive black holes and feedback from active galactic nuclei (AGN) in the form of a dual jet-heating mode. For this simulation we implemented a hybrid MPI-OpenMP version of the RAMSES code, specifically targeted for modern many-core many thread parallel architectures. For the post-processing, we extended the Friends-of-Friend (FoF) algorithm and developed a new galaxy finder to analyse the large outputs of HR5. The simulation successfully reproduces many observations, such as the cosmic star formation history, connectivity of galaxy distribution and stellar mass functions. The simulation also indicates that hydrodynamical effects on small scales impact galaxy clustering up to very large scales near and beyond the baryonic acoustic oscillation (BAO) scale. Hence, caution should be taken when using that scale as a cosmic standard ruler: one needs to carefully understand the corresponding biases. The simulation is expected to be an invaluable asset for the interpretation of upcoming deep surveys of the Universe.

• Analytical Science and Technology
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• v.37 no.2
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• pp.123-129
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• 2024

We present a rapid method for the determination of Cs, Sr, and Ba, heat generators found in highly active liquid wastes, by gas-pressurized extraction chromatography (GPEC) using a column containing a cation-exchange resin. GPEC is a microscale column chromatographic technique that uses a constant flow rate of solvent (0.07 mL/min) with pressurized nitrogen gas supplied through a valve. In particular, because this method uses a small sample volume (a few hundred microliters), it produces less chemical waste and allows for faster separation compared to traditional column chromatography. In this study, we evaluated the separation of Cs, Sr, and Ba using GPEC. The eluate from the column (GPEC or conventional column chromatography) was quantitatively analyzed using inductively coupled plasma-mass spectrometry to measure the column recovery and precision. The column reproducibility of the proposed GPEC system (RSDs of recoveries) ranged from 2.7 to 4.1 %, and the column recoveries for the three elements ranged from 72 to 98% when aqueous HCl was used as the eluent. The GPEC results are slightly different in efficiency and separation resolution compared to those of conventional column chromatography because of the differences in the eluent flow rate as well as the internal diameter and length of the column. However, the two methods had similar recoveries for Cs and Sr, and the precision of GPEC was improved by two-fold. Remarkably, the solvent volume required for GPEC analysis was five times lower than that of the conventional method, and the total analysis time was 11 times shorter.

• Food Science and Preservation
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• v.31 no.1
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• pp.1-14
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• 2024

The utilization of coatings composed of bio-based materials in the processing and preservation of meat presents an environmentally conscious, secure, cost-effective, and superior method for prolonging the storage life of meat while also preserving its nutritional value. In this study, changes in physical, chemical, and microbiological characteristics of freshly cut beef coated with distilled water (control) and keratin-starch composites (K-S) functionalized with 0.0-, 0.2-, 0.6-, and 1.0-mL avocado peel polyphenolic-rich extract (APPPE) kept at 4℃ for 12 days were evaluated periodically at 3-day interval using standard techniques. Keratin was extracted from waste feathers, while starch was obtained from ginger rhizomes. Following a 12-day storage period, beef coated with APPPE-enriched K-S composites exhibited a significant (p<0.05) improvement in shelf life by minimizing deteriorative changes in pH and color (as determined by metmyoglobin level) in addition to inhibiting oxidative changes in lipids (as determined by TBARS level) and proteins (protein carbonyl level) in comparison to control and K-S composite without APPPE. Furthermore, microbial growth was significantly (p<0.05) suppressed in meat coated with K-S composite functionalized with APE at 0.6 and 1.0 mL compared to the control. The study suggested that APPPE-enriched K-S composite could offer an eco-friendly and safe food preservation technique for fresh meat.

• Industry Promotion Research
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• v.9 no.1
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• pp.13-20
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• 2024

In this study, we conducted a compositional analysis of five darkening shampoos available in the South Korean market and evaluated their active ingredients and safety based on the analysis results. GC-MS analysis was employed to identify the main components of each shampoo, revealing discrepancies between the detected compounds and the ingredient lists provided by the manufacturers. These differences are interpreted as being due to the limitations of the GC-MS analysis and the volatility of certain compounds. Further investigations were carried out to explore compounds potentially contributing to hair darkening. However, it was not definitively concluded that these compounds are directly involved in the hair darkening process. It is speculated that they may enhance hair care product performance and offer additional benefits to hair, or improve product texture, stability, or preservation. Additionally, the GC-MS analysis identified several compounds with potential safety concerns, necessitating caution when used as cosmetic ingredients.

• Journal of Physiology & Pathology in Korean Medicine
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• v.38 no.1
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• pp.22-26
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• 2024

The purpose of this study was to identify the applicability, main compounds, and target genes of Cnidii Fructus (CF) in the treatment of gastritis using network pharmacology. The compounds in CF were searched in Traditional Chinese Medicine Systems Pharmacology Database and Analysis Platform (TCMSP) and a database of medicinal materials and chemical compounds in Northeast Asian traditional medicine (TM-MC). The target gene information of the compounds was collected from pubchem and cross-compared with the gastritis-related target gene information collected from Genecard to derive the target genes. Gene ontology (GO) analysis and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis were performed on the derived target genes. Afterwards, network analysis between compounds and disease target genes was performed using cytoscape. We identified 121 active compounds and 139 target genes associated with gastritis. Pathways derived from the GO biological process and KEGG pathway DB primarily focus on target genes related to inflammation (IL-6, IL-8, TNF production, NF-κB transcription factor activity, and NF-κB signaling pathway) and cell death (PI3K-Akt, FoxO). Major targets for CF treatment of gastritis include TP53, TNF, BCL2, EGFR, NFKB1, ABCB1, PPARG, PTGS2, IL6, IL1B, and SOD1, along with major compounds such as coumarin, osthol, hexadecanoic acid, oleic acid, linoleic acid, and stigmasterol. This study provided CF's applicability for gastritis, related compounds, and target information. Evaluating CF's effectiveness in a preclinical gastritis model suggests its potential use in clinical practice for digestive system diseases.

• Annals of Occupational and Environmental Medicine
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• v.35
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• pp.10.1-10.10
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• 2023

The purpose of this paper was to review the problems relating to Korea's occupational health services and suggest ways to improve them. Korea can be classified as a welfare state type of conservative corporatism partially interwoven with liberalism. While experiencing compressed economic growth, the economic sectors of developed (excess areas) and developing (deficient areas) countries are interwoven. Therefore, it is necessary to perfect conservative corporatism along with a complementary reinforcement of liberal contents and to apply a multilayered approach focusing on complementing the deficient areas. It is essential to form a national representative indicator related to occupational health, and a strategy for selection and concentration is needed. The proposed central indicator is the occupational health coverage rate (OHCR), which is the number of workers who have applied for mandatory occupational health services under the Occupational Safety and Health Act in the numerator with the total working population in the denominator. This paper proposes ways to raise the OHCR, which is currently at the level of 25%-40%, to 70%-80%, which is the level of Japan, Germany, and France. To achieve this target, it is necessary to focus on small businesses and vulnerable workers. This is an area of market failure and requires the active input of community-oriented public resources. For access to larger workplaces, the marketability of services should be strengthened and personal intervention using digital health resources should be actively attempted. Taking a national perspective, work environment improvement committees with tripartite (labor, management, and government) participation for improvement of the working environment need to be established at the center and in the regions. Through this, prevention funds linked to industrial accident compensation and prevention could be used efficiently. A national chemical substance management system must be established to monitor the health of workers and the general public.

• Herbal Formula Science
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• v.32 no.1
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• pp.39-49
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• 2024

Objectives : The purpose of this study was to investigate the molecular targets and pathways of anti-inflammatory effects of Jakyakgamchotang with corydalis tuber (JC) using network pharmacology. Methods : The compounds in constituent herbal medicines of JC were searched in TCM systems pharmacology (TCMSP). Target gene informations of the components were collected using chemical-target interactions database provided by Pubchem. Afterwards, network analysis between compounds and inflammation-related target genes was performed using cytoscape. Go enrichment analysis and Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis were performed on inflammation-related targets using DAVID database. Results : 70 active compounds related to inflammation were identified, and 295 target genes related to the anti-inflammatory activity of the compound of JC were identified. In the Go biological process DB and KEGG pathway DB, "inflammatory response", "cellular response to lipopolysaccharide", "positive regulation of interleukin-6 production", and "positive regulation of protein kinase B. signaling", "positive regulation of ERK1 and ERK2 cascade", "positive regulation of I-kappaB kinase/NF-kappaB signaling", "negative regulation of apoptotic process", and "PI3K-Akt signaling pathway" were found to be mechanisms related to the anti-inflammatory effects related to the target genes of JC. The main compounds predicted to be involved in the anti-inflammatory effect of JC were quercetin, licochalcone B, (+)-catechin, kaempferol, and emodin. Conclusions : This study provides the molecular targets and potential pathways of JC on inflammation. It can be used as a basic data for using JC for various inflammatory disease in traditional korean medicine clinic.