• Journal of the Korean Crystal Growth and Crystal Technology
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• v.33 no.6
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• pp.255-260
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• 2023

As demanding the detection of explosive molecules, it is required to develop rapidly and precisely responsive sensors with ultra-high sensitivity. Since two-dimensional semiconductors have an atomically thin body nature where mobile carriers accumulate, the abrupt modulation carrier in the thin body channel can be expected. To investigate the effectiveness of WSe₂ semiconductor materials as a detection material for TNT (Trinitrotoluene) explosives, WSe₂ was synthesized using thermal chemical vapor deposition, and afterward, WSe₂ FETs (Field Effect Transistors) were fabricated using standard photo-lithograph processes. Raman Spectrum and FT-IR (Fourier-transform infrared) spectroscopy reveal that the adsorption of TNT molecules induces the structural transition of WSe₂ crystalline. The electrical properties before and after adsorption of TNT molecules on the WSe₂ surface were compared; as -50 V was applied as the back gate bias, 0.02 μA was recorded in the bare state, and the drain current increased to 0.41 μA with a dropping 0.6% (w/v) TNT while maintaining the p-type behavior. Afterward, the electrical characteristics were additionally evaluated by comparing the carrier mobility, hysteresis, and on/off ratio. Consequently, the present report provides the milestone for developing ultra-sensitive sensors with rapid response and high precision.

• Journal of Life Science
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• v.34 no.5
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• pp.287-295
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• 2024

Hepatocellular carcinoma (HCC) is the second leading cause of cancer-related mortality worldwide, necessitating novel therapeutic strategies. The chemotherapeutic agents used to treat HCC patients are toxic and have serious side effects. Therefore, we investigated the efficacy of anticancer drugs that reduce side effects by targeting tumor cells without causing cytotoxicity in healthy hepatocytes. Berberine, an isoquinoline alkaloid derived from plant compounds, has emerged as a potential candidate for cancer treatment due to its diverse pharmacological properties. The effect of berberine on HepG2 cell viability was determined using the 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium bromide assay. HepG2 cell proliferation was determined through a colony-forming assay. The effects of berberine on HepG2 cell migration were evaluated using a wound-healing assay. Berberine inhibited the proliferation of HepG2 cells, as well as colony formation and migration. Berberine treatment increased the expression of autophagy-related genes and proteins, including Beclin-1 and LC3-II, and elevated the activities and mRNA expression of Caspase-9 and Caspase-3. Additionally, in experiments utilizing the Cell-Derived Xenograft animal model, berberine treatment reduced tumor size and weight in a concentration-dependent manner. These results demonstrate the potential of berberine as a versatile anticancer agent with efficacy in both cellular and animal models of hepatocellular carcinoma. The findings herein shed light on berberine's efficacy against HCC, presenting opportunities for targeted and personalized therapeutic interventions.

• The Journal of the Convergence on Culture Technology
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• v.10 no.3
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• pp.413-420
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• 2024

After Friedrich Nietzsche's advocacy of nihilism, many literary works, dramas, and films have depicted aspects of human psychology associated with nihilism. Animation, too, has been used to convey nihilism, with narratives infused with nihilistic themes produced as both TV series and theatrical animations. Particularly, animation, as a visual medium capable of realizing any imaginative image unlike other media, possesses distinctive characteristics from live-action cinematography and differs from comics in its temporal properties. Hence, this study aims to analyze how Nietzsche's defined three stages of nihilism are represented within animation characters and how they construct various scenarios, using the anime "Attack on Titan" as a case study. The research unfolds by first examining Nietzsche's types of nihilism and the three stages through a review of literature, while also investigating the portrayal of nihilism in mass media and considering the unique attributes of animation. Secondly, building upon the literature review, the analysis interprets the narrative and constructed world of the chosen case study from a nihilistic perspective, examining four major characters through the stages of passive nihilism, active nihilism, and eternal recurrence. The findings demonstrate that the anime conveys two messages regarding negation and affirmation of one's life and existence, thereby offering viewers an opportunity to deeply contemplate human existence. This study is considered significant as it examines how Nietzschean nihilism is portrayed within the popular entertainment medium of animation.

• Korean Chemical Engineering Research
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• v.62 no.2
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• pp.147-152
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• 2024

Most medical sensors are disposable products. In order to reduce inspection and diagnosis costs, it is more important to develop the inexpensive electrode materials. We fabricated the CuO NPs/PANI/E-PGE as an electrode material for disposable electrochemical sensors and applied it to a non-enzymatic glucose sensor. For surface activation of PGE, pretreatment was performed using chemical and electrochemical methods, respectively. Electrochemical properties according to the pretreatment method were analyzed through chronoamperometry (CA), cyclic voltammetry (CV) and electrochemical impedance (EIS). From these analytical results, the electrochemically pretreated PGE (E-PGE) was finally adopted. The non-enzymatic glucose sensor based on CuO NPs/PANI/E-PGE shows sensitivity of 239.18 mA/mM×cm² (in a linear range of 0.282~2.112 mM) and 36.99 mA/mM×cm² (3.75423~50 mM), detection limit of 17.6 μM and good selectivity. Based on the results of this study, it was confirmed that the modified PGE is a high-performance electrode material. Therefore, these electrodes can be applied to a variety of disposable sensors.

• Food Science and Preservation
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• v.22 no.2
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• pp.275-280
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• 2015

Among the naturally occurring antioxidants, polyphenols are widely distributed in various fruits, vegetables, wines, juices, and plant-based dietary sources and divided into several subclasses that included phenolic acid, flavonoids, stilbenes, and lignans. As part of our continuing search for bioactive food ingredients, the antioxidant and ${\alpha}$-glucosidase inhibitory activities of the aqueous ethanolic extract from the aerial parts of Ainsliaea acerifolia were investigated in vitro. The antioxidant properties were evaluated via radical scavenging assays using 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulphonic acid) ($ABTS^+$) radicals. In addition, the anti-diabetic effect of A. acerifolia extracts was tested via ${\alpha}$-glucosidase inhibitory assay. Furthermore, the total phenolic contents were determined using a spectrophotometric method. All the tested samples showed dose-dependent radical scavenging and ${\alpha}$-glucosidase inhibitory activities. In particularly, the ${\alpha}$-glucosidase inhibitory and radical scavenging properties of the ethyl acetate (EtOAc)-soluble portion from the aerial parts of the A. acerifolia were higher than those of the other solvent-soluble portions. These results suggest that A. acerifolia could be considered a new potential source of natural antioxidants and antidiabetic ingredients. More systematic investigation of the aerial parts of A. acerifolia will be performed for the further development of anti-oxidative and antidiabetic drugs.

• Journal of the Korean Recycled Construction Resources Institute
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• v.5 no.3
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• pp.267-274
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• 2017

This study discusses the applicability of environmental friendly EVA based butyl rubber self-adhesive waterproof sheet designed to prevent corrosion of large scale pipes used in the water treatment facilities during th water treatment process. The experiments conducted tested the waterproofing sheet's adhesion strength on the steel surface of the pipes and checked for whether the material has the proper response properties against the various environmental conditions. In addition, it the sheet adhered to the steel pipe was to see if the adhesion hold against the water pressure due to the ingress of inflow water. Finally, the waterproofing sheet's adhesion strength was tested on a rusted steel surface to confirm whether the material has the necessary properties to secure stable adhesion strength and prevent corrosion of steel pipes at the same time during the process of installation or maintenance. As a result, the self-adhesive waterproof sheets showed that all attachments in the untreated, long term pressuring, immersion in chemical substance (hydrochloric acid, hypochlorous acid, sodium hydroxide), low temperature ($-20^{\circ}C$) conditions showed a adhesion performance of higher than 1.5N/mm, which is the performance standard of KS F 4934. Also, in the testing to check for the adhesion property against inverse water pressure, it was observed that the adhesion failure did not occur even up to $3.0N/mm^2$ pressure. Also, in the process of assessing the adhesion performance on rusted steel surface, specimens after 12 hours of corrosion treatment was shown to have 2.1N/mm, and specimens after 168 hours of corrosion treatment was shown to have 2.0N/mm adhesion strength performance.

• Food Science and Preservation
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• v.22 no.3
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• pp.437-442
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• 2015

In a continuing screening of selected medicinal plants native to South Korea, the antioxidant and pancreatic lipase inhibitory activities of an aqueous methanolic extract from the heartwood of Aquilaria agallocha were investigated. Eighty percent of the methanolic extract of A. agallocha was further divided into $CH_2Cl_2$, EtOAc and n-BuOH in order to yield four solvent-soluble portions, namely $CH_2Cl_2$-soluble, EtOAc-soluble, n-BuOH-soluble and $H_2O$ residue. The antioxidant properties were evaluated by employing radical scavenging assays using 1,1-diphenyl-2-picrylhydrazyl (DPPH) and 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulphonic acid) ($ABTS^+$) radicals, while the anti-obesity efficacy of A. agallocha extracts and solvent-soluble portions were tested by porcine pancreatic lipase assay. All tested samples showed dose-dependent radical scavenging and pancreatic lipase inhibitory activities. Among the tested extracts and solvent-soluble portions, the $CH_2Cl_2$-soluble portion showed much higher radical scavenging activity and pancreatic lipase inhibitory properties when compared with other solvent-soluble portions. This result suggested that there was a significant relationship between the total phenolic content and biological efficacies, and A. agallocha extract might be considered as a new potential source of natural antioxidants and as a pancreatic lipase inhibitory source. A more systematic investigation of this biomass will be performed for further investigation of activity against antioxidative and anti-obesity effects.

• Food Science and Preservation
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• v.22 no.3
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• pp.428-436
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• 2015

Five extraction conditions (AE, autoclave extraction; OE, oven extraction; HWSE, hot water and sonication extraction; HWASE, hot water acidified with 0.5% (v/v) acetic acid and sonication extraction; and BE, boiling extraction) were examined to compare the effects of different hot water extraction methods on the antioxidant properties of blueberries. The extraction yields of the AE, OE, HWSE, HWASE, and BE were 7.94%, 8.35%, 8.55% 9.15%, and 8.50%, respectively. The polyphenol and flavonoid contents of AE were 3.47 mg GAE/g and 1.59 mg RE/g, respectively, which were highest centents among others. Those of OE were ranked second to the highest. The total anthocyanin content of HWSE (5.29 mg/g) was significantly higher than that of others whereas that of AE showed the lowest content (0.96 mg/g). The order of ABTS radical and alkyl radical scavenging activities was as follows: AE > BE > OE > HWSE > HWASE. The antioxidant properties were considerably correspondent with the total polyphenol and flavonoid content. DPPH radical scavenging activity was quite high in HWSE, AE, and BE extraction, however, there were no significant differences among the five extraction methods in the aspect of $Fe^{2+}$ ion chelating activities. Moreover, AE showed the highest SOD activity, and protected the dermal fibroblast the best against $H_2O_2$-induced cytotoxicity. In conclusion, it was suggested that the autoclave extraction (AE) would be the most effective method for preparing blueberry hot water extracts with relatively high antioxidant activities.

• Journal of the Korean Vacuum Society
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• v.17 no.4
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• pp.359-364
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• 2008

We have investigated optical and structural properties of $Al_{0.3}Ga_{0.7}N$/GaN and $Al_{0.3}Ga_{0.7}N/GaN/Al_{0.15}Ga_{0.85}N/GaN$ heterostructures (HSs) grown by metal-organic chemical vapor deposition, by means of Hall measurement, high-resolution X-ray diffraction, and temperature- and excitation power-dependent photoluminescence (PL) spectroscopy. A strong GaN band edge emission and its longitudinal optical phonon replicas were observed for all the samples. At 10 K, a 2DEG-related PL peak located at ${\sim}\;3.445\;eV$ was observed for $Al_{0.3}Ga_{0.7}N$/GaN HS, while two 2DEG peaks at ${\sim}\;3.42$ and ${\sim}\;3.445\;eV$ were observed for $Al_{0.3}Ga_{0.7}N/GaN/Al_{0.15}Ga_{0.85}N/GaN$ HS due to the additional $Al_{0.15}Ga_{0.85}N$ layers. Moreover, the emission intensity of the 2DEG peak was higher in $Al_{0.3}Ga_{0.7}N/GaN/Al_{0.15}Ga_{0.85}N/GaN$ HS than in $Al_{0.3}Ga_{0.7}N$/GaN HS probably due to an effective confinement of the photo-excited holes by the additional $Al_{0.15}Ga_{0.85}N$ layers. The 2DEG-related emission intensity decreased with increasing temperature and disappeared at temperatures above 150 K. To investigate the origin of the new 2DEG peaks, the energy-band structure for multiple AlGaN/GaN HSs were simulated and compared with the experimental data. As a result, the observed high- and low-energy peaks of 2DEG can be attributed to the spatially-separated 2DEG emissions formed at different AlGaN/GaN heterointerfaces.

• Korean Journal of Microbiology
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• v.51 no.3
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• pp.231-240
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• 2015

In this study, a total of 16 conjugated linoleic acid (CLA) producing lactic acid bacteria (LAB) were isolated from fermented foods. Among those strains, the S48 and P1201 strains were capable of producing higher CLA contents than other LABs. The two strains were classified as Lactobacillus plantarum based on morphological, physiological, chemotaxonomic, and molecular-genetic properties. The survival rates of these strain appeared to be 59.57% and 62.22% under artificial gastric conditions after 4 h at pH 2.5, respectively. These strains produced the cis-9, trans-11, and trans-10, cis-12 CLA isomers from 8% skim milk medium supplemented with the different free LA concentration at $37^{\circ}C$ for 48 h and the production of two CLA isomers constantly increased in the growth until 48 h of incubation. After 48 h of fermentation, the levels of CLA appeared highest in steamed soy-powder milk than fresh and roasted soy-powder milks. In particular, the CLA contents were produced $183.57{\mu}g/ml$ and $198.72{\mu}g/ml$ from steamed soy-powder milk after fermentation (48 h) with S48 and P1201 strains, respectively.