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Thermal catalytic device for toluene decomposition via direct heating
Hyeonjin Eom,Seunghwan Ahn,Na Kyong Kim,Hyun Wook Kang 대한환경공학회 2023 Environmental Engineering Research Vol.28 No.4
A thermal catalytic device that reduces the energy required for the catalytic oxidation of volatile organic compounds (VOCs) was developed. The catalytic oxidation of VOCs is typically performed under indirect heating conditions resulting in high energy consumption. The proposed device drastically decreases the energy consumed and increases the amount of toluene decomposed during catalytic oxidation because the catalysts are heated directly via a carbon nanotube (CNT) element. The proposed device consists of a glass-fiber textile coated in CNTs, α-MnO₂ nanostructures, and Pt nanostructures. The effect of different α-MnO₂ nanostructures (granular and urchin-like) on device performance was investigated. Moreover, the effect of each device component on the toluene decomposition efficiency and energy consumption of the device was explored by determining the toluene concentration of gaseous toluene after the catalytic oxidation process and the associated energy consumption. The device featuring urchin-like α-MnO₂ nanostructures coated in a thin layer of Pt achieves higher toluene decomposition efficiency than the device featuring granular α-MnO₂ nanostructures coated in Pt nanoparticles. Moreover, the device featuring urchin-like α-MnO₂ nanostructures coated in a thin Pt layer achieves higher toluene decomposition efficiency and lower energy consumption under direct heating conditions than under conventional indirect heating conditions.
Youngran Na,Jihye Jeong,Sujin Shin,Sujeong Hwang,Hyeonjin Kim,Yeonghee Kwon,Yonkoung Park 한국식품영양과학회 2021 한국식품영양과학회 학술대회발표집 Vol.2021 No.10
The aim of this study was to determine and analyze probiotic contents, coliform E. coli group of 113 samples of health functional foods containing probiotic bacteria distributed in 2020. In all 113 health functional foods, probiotic contents were detected more than the number of bacteria guaranteed in the product, and all coliforms were also negative. The average of probiotic contents per daily intake was 2.5×10<SUP>10</SUP> CFU. By packaging type, the average content of probiotics was highest in capsule products. The average content of imported products was higher than that of domestic products. The changes due to the preservation methods were also determined and analyzed in six probiotic products. The effects of preservation temperature (4℃, 20℃, and 37℃) and storage period (test once every 4 weeks up to 48 weeks) on probiotic contents. After 48 weeks, the average reduction in probiotic content was by 63.3%; the lowest reduction occurred at 4℃ and the highest reduction occurred at 37℃. In addition, 2 of the 6 products showed a rapid decrease in probiotic content by more than 90% at 37℃ after a storage period of 4 weeks.
Kyong Kim, Na,Hee Kang, Dong,Eom, Hyeonjin,Wook Kang, Hyun Elsevier 2019 APPLIED SURFACE SCIENCE - Vol.470 No.-
<P><B>Abstract</B></P> <P>As water scarcity has become a major global problem, fog-harvesting technologies are considered an effective sustainable solution for water resources. Here, we report a novel approach to the fog-harvesting technology using zinc oxide-silver hierarchical nanostructures to mimic the <I>Stenocara</I> beetle’s back. Vertically aligned zinc oxide nanowires are first fabricated by a cost-effective and scalable hydrothermal method to produce a superhydrophilic surface. Silver nanoparticles are then selectively synthesized by an additional photo-induced synthetic process on the zinc oxide nanowire surfaces to form a hydrophobic surface using the hierarchical nanostructures. The fog-harvesting performance was investigated using an artificial fog flow and by measuring the amount of harvested water for efficient fog harvesting. On the superhydrophilic surface, although the water droplets immediately were captured, they formed a puddle at the bottom of the surface due to the high adhesion between water and the surface. In contrast, on the hydrophobic surface, the capturing rate was very low even though the water droplets easily rolled off the surface. Compared to the non-patterned surface, the captured water film on the patterned hydrophilic region grew rapidly into a spherical shape and separated from the surface due to the surrounding hydrophobic regions. As a result, the patterned surface with 0.5 mm pattern size afforded a higher fog collection rate of 1233 mg/h than those of the superhydrophilic and hydrophobic surfaces of 1105 mg/h and 879 mg/h respectively.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Facile, low-cost, and easy to operate method for the fabrication of mimetic <I>Stenocara</I> beetle’s back. </LI> <LI> Controlling a Surface wettability by the silver nanoparticles on the zinc oxide nanowires. </LI> <LI> Selectively synthesizing the silver nanoparticles and zinc oxide nanowires hierarchical nanostructure. </LI> <LI> Efficient water collection by hydrophobic surface with patterned hydrophilic regions. </LI> <LI> Application to multifunctional surface for water collection and desalination. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>
Effects of Sangju Honey on Oral Squamous Carcinoma Cells
Nangwon Yee,Hyeonjin Kim,Eungyung Kim,Yong Ho Cha,Lei Ma,Na Eun Cho,Dongwook Kim,Chae Yeon Kim,Sung-Hyun Kim,Zaeyoung Ryoo,이준구,김명옥 대한암예방학회 2022 Journal of cancer prevention Vol.27 No.4
Since ancient times, honey has been used in traditional medicine owing to its pharmacological effects. It possesses anticancer properties. However, the therapeutic implications of Sangju honey in cancer remains unknown. Therefore, we aimed to demonstrate the potential anticancer effects of Sangju honey on human oral squamous cell carcinoma (OSCC), particularly focusing on epithelial–mesenchymal transition (EMT) and apoptotic and mitogen-activated protein kinase (MAPK) signaling pathways. Ca9- 22 and YD-10B human OSCC cells were treated with 0.25% or 0.5% Sangju honey, and the cell viability was examined using the Cell Counting Kit-8 assay. Cell morphology studies were conducted to observe morphological changes, and the wound-healing assay was performed to evaluate the proliferation of honey-treated OSCC cells. Western blot analysis was conducted to investigate protein expression related to EMT and apoptotic and MAPK signaling pathways. Sangju honey reduced cell viability, induced morphological changes, and significantly suppressed the proliferation and migration of Ca9-22 and YD-10B cells. The expression of E-cadherin and N-cadherin was increased and decreased, respectively, in both OSCC cell lines. Moreover, Sangju honey stimulated apoptosis by increasing the expression of p21, p53, cleaved caspase 3, and caspase 9. Furthermore, it downregulated the expression of phospho (p)-extracellular signal-regulated kinases 1 and 2, p-c-Jun amino-terminal kinase, and p-p38 in Ca9-22 and YD-10B cells. Sangju honey inhibits Ca9-22 and YD-10B cell proliferation by regulating EMT, inducing apoptosis, and suppressing the MAPK signaling pathway. Thus, it is a potential anticancer agent for human OSCC.
Synaptic Device based on Resistive Switching Memory using Single-walled Carbon Nanotubes
Dong Jun Jang,Hyunwoo Ryu,Hyeonjin Cha,Na-Young Lee,Younglae Kim,Min-Woo Kwon 대한전자공학회 2022 Journal of semiconductor technology and science Vol.22 No.5
Recently, research has been conducted on a biomimetic system called artificial neural networks (ANNs) to overcome the limits of Von Neumann’s system. Spiking neural networks (SNNs) in ANNs are hardware systems that implement NNs’ low-power parallel processing. The electrical characteristics of synaptic devices, which affect learning and memory, are important in SNN construction. Synaptic devices based on resistive switching are called memristors and have sufficient learning capabilities, such as spike-timing-dependent plasticity gradual switching [1]. However, memristors require high switching voltages and currents, resulting in high power consumption. To reduce the operation voltage of the synapse, new materials must be developed for the switching oxide and metal electrode. The conventional memristor structure comprises metal-oxide-metal (MOM) or metal-oxide-N+Si (MOS). This study proposes a synaptic device with single-walled carbon nanotubes (SWCNTs) with excellent electrical and mechanical properties to lower the switching voltage and fabricate a metal-oxide-SWCNTs-N+Si (MOCS)-structured synaptic device using SWCNTs as a metal electrode, as shown in Fig. 1 [2]. Finally, the electrical characteristics of MOM, MOS, and MOCS structures are analyzed and compared.