• Korean Chemical Engineering Research
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• v.61 no.3
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• pp.341-347
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• 2023

In PEMFC, PtCo/C alloy catalysts are widely used because of good performance and durability. However, few studies have been reported on the durability of carbon supports of PtCo/C evaluated at high voltages (1.0~1.5 V). In this study, the durability of PtCo/C catalysts and Pt/C catalysts were compared after applying the accelerated degradation protocol of catalyst support. After repeating the 1.0↔1.5V voltage change cycles, the mass activity, electrochemical surface area (ECSA), electric double layer capacitance (DLC), Pt dissolution and the particle growth were analyzed. After 2,000 cycles of voltage change, the current density per catalyst mass at 0.9V decreased by more than 1.5 times compared to the Pt/C catalyst. This result was because the degradation rate of the carbon support of the PtCo/C catalyst was higher than that of the Pt/C catalyst. The Pt/C catalyst showed more than 1.5 times higher ECSA reduction than the PtCo/C catalyst, but the corrosion of the carbon support of the Pt/C catalyst was small, resulting in a small decrease in I-V performance. In order to improve the high voltage durability of the PtCo/C catalyst, it was shown that improving the durability of the carbon support is essential.

• BMB Reports
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• v.56 no.6
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• pp.359-364
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• 2023

KAI1/CD82, a membrane tetraspanin protein, can prevent various cancers and retinal disorders through its anti-angiogenic and anti-metastatic capacity. However, little is known about its anti-inflammatory effect and molecular mechanism. Therefore, the present study aimed to inLPSvestigate effect of a recombinant protein of the large extracellular domain of human KAI1 (Gly 111-Leu 228, rhKAI1) on lipopolysaccharides (LPS)-stimulated RAW264.7 macrophage-like cells and mouse bone marrow-derived macrophages (BMDM) and to identify its underlying mechanism. Our data showed that rhKAI1 suppressed expression levels of classically macrophages (M1) phenotype-related surface markers F4/80+CD86+ in LPS-stimulated BMDM and RAW264.7 cells. In addition, LPS markedly increased mRNA expression and release levels of pro-inflammatory cytokines and mediators such as interleukin (IL)-1β, IL-6, tumor necrosis factor-α, cyclooxygenase-2, nitric oxide and prostaglandin E2, whereas these increases were substantially down-regulated by rhKAI1. Furthermore, LPS strongly increased expression of NF-κB p65 in the nuclei and phosphorylation of ERK, JNK, and p38 MAPK. However, nuclear translocation of NF-κB p65 and phosphorylation of JNK were greatly reversed in the presence of rhKAI1. Especially, rhKAI1 markedly suppressed expression of toll-like receptor (TLR4) and prevented binding of LPS with TLR4 through molecular docking predict analysis. Importantly, Glu 214 of rhKAI1 residue strongly interacted with Lys 360 of TLR4 residue, with a binding distance of 2.9 Å. Taken together, these findings suggest that rhKAI1 has an anti-inflammatory effect on LPS-polarized macrophages by interacting with TLR4 and down-regulating the JNK/NF-κB signaling pathway.

• Journal of the Society of Naval Architects of Korea
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• v.60 no.4
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• pp.222-230
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• 2023

In the present work, the scale effect on the Boil-Off Rate (BOR) was investigated based on an analytical method to systematically evaluate the thermal performance of a Liquefied Natural Gas (LNG) Cargo Containment System (CCS). A two-dimensional thermal resistance network model was developed to accurately estimate the heat ingress into the CCS from the outside. The analysis was performed for the KC-1 LNG membrane tank under the IGC and USCG design conditions. The ballast compartment of both the LNG tank and cofferdam was divided into six sections and a thermal resistance network model was made for each section. To check the validity of the developed model, the analysis results were compared with those from existing literature. It was shown that the BOR values under the IGC and USCG design conditions were agreed well with previous numerical results with a maximum error of 1.03% and 0.60%, respectively. A SDR, the scale factor of the LNG CCS was introduced and the BOR, air temperature of the ballast compartment, and the surface temperature of the inner hull were obtained to examine the influence of the SDR on the thermal performance. Finally, a correlation for the BOR was proposed, which could be expressed as a simple formula inversely proportional to the SDR. The proposed correlation could be utilized for predicting the BOR of a full-scale LNG tank based on the BOR measurement data of lab-scale model tanks.

• Journal of Life Science
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• v.34 no.4
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• pp.279-285
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• 2024

The zonula occludens (ZO) protein serves as a scaffolding protein, providing structural support at the junctions between cells and the cytoplasmic surface. It acts as a bridge between integral membrane proteins and the cytoskeleton. Besides its structural role, it also participates in regulating cell growth and proliferation. Recent studies have highlighted the involvement of ZO protein in various diseases, including cancer. Specifically, research has indicated that ZO protein influences the cancer microenvironment surrounding cancer cells, thereby facilitating their growth and development. ZO proteins exert diverse functions in the cancer microenvironment, impacting processes such as angiogenesis, inflammatory responses, the epithelial-mesenchymal transition, and interactions with mesenchymal stem cells. The specific mechanisms vary depending on the type of cancer and environmental conditions. Recent research unveiled several signaling pathways involving ZO protein, which could potentially impede cancer progression in the tumor microenvironment. Consequently, these insights open avenues for novel treatment strategies. While the numerous physiological, structural, and morphological roles of ZO protein have been observed at the cellular and in vivo levels, understanding the signaling mechanisms it operates in vivo and how these mechanisms influence the cancer microenvironment remains a challenge. In this review, we delineate the characteristics and regulatory mechanisms of ZO protein in the context of the cancer microenvironment. Additionally, we propose leveraging the properties of ZO protein to devise defense mechanisms within the cancer cell environment and provide an overview of its in vivo role.

• IMMUNE NETWORK
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• v.20 no.5
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• pp.41.1-41.11
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• 2020

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV2) is a positive-sense single-stranded RNA (+ssRNA) that causes coronavirus disease 2019 (COVID-19). The viral genome encodes twelve genes for viral replication and infection. The third open reading frame is the spike (S) gene that encodes for the spike glycoprotein interacting with specific cell surface receptor - angiotensin converting enzyme 2 (ACE2) - on the host cell membrane. Most recent studies identified a single point mutation in S gene. A single point mutation in S gene leading to an amino acid substitution at codon 614 from an aspartic acid 614 into glycine (D614G) resulted in greater infectivity compared to the wild type SARS-CoV2. We were interested in investigating the mutation region of S gene of SARS-CoV2 from Korean COVID-19 patients. New mutation sites were found in the critical receptor binding domain (RBD) of S gene, which is adjacent to the aforementioned D614G mutation residue. This specific sequence data demonstrated the active progression of SARS-CoV2 by mutations in the RBD of S gene. The sequence information of new mutations is critical to the development of recombinant SARS-CoV2 spike antigens, which may be required to improve and advance the strategy against a wide range of possible SARS-CoV2 mutations.

• Journal of Periodontal and Implant Science
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• v.53 no.5
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• pp.347-361
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• 2023

Purpose: Exosomes are membrane vesicles that are present in body fluids and contain proteins, lipids, and microRNA (miRNA). Periodontal tissue examinations assess the degree of periodontal tissue destruction according to the probing depth (PD), clinical attachment loss (CAL), bleeding on probing, and X-ray examinations. However, the accurate evaluation of the prognosis of periodontitis is limited. In this study, we collected saliva from patients before and after initial periodontal therapy (IPT) and compared changes in the clinical parameters of periodontitis with changes in the components of salivary exosomes. Methods: Saliva was collected from patients with stage III and IV periodontitis at the first visit and post-IPT. Exosomes were purified from the saliva, and total protein and RNA were extracted. Changes in expression levels of C6, CD81, TSG101, HSP70, and 6 kinds of miRNA were analyzed by western blots and real-time polymerase chain reaction. Results: Patients with increased C6 expression after IPT had significantly higher levels of periodontal inflamed surface area (PISA), miR-142, and miR-144 before and after IPT than patients with decreased C6 expression after IPT. Patients with decreased and unchanged CD81 expression after IPT showed significantly higher PD, CAL, and PISA before IPT than after IPT. Patients with decreased and unchanged TSG101 expression after IPT had significantly higher PD before IPT than after IPT. Patients with increased HSP70 expression after IPT had significantly higher PD and PISA before and after IPT than patients with unchanged HSP70 after IPT. The expression levels of miR-142, miR-144, miR-200b, and miR-223 changed with changes in the levels of C6, CD81, TSG101, and HSP70 in the salivary exosomes of periodontitis patients before and after IPT. Conclusions: The expression levels of proteins and miRNAs in salivary exosomes significantly changed after IPT in periodontitis patients, suggesting that the components of exosomes could serve as biomarkers for periodontitis.

• Journal of the Korea Organic Resources Recycling Association
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• v.18 no.1
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• pp.57-65
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• 2010

Two types of microbial fuel cells(MFC) were continuously operated using synthetic wastewater. One was conventional two-chambered MFC using proton exchange membrane(PEM-MFC), the other was upflow type membraneless MFC(ML-MFC). Graphite felt was used as a anode in PEM-MFC. In membraneless MFC, two MFCs were operated using porous RVC(reticulated vitreous carbon) as a anode. Graphite felt was used as a cathode in all experiments. In experiment of PEM-MFC, the COD removal rate based on the surface area of anode was about $3.0g/m^2{\cdot}d$ regardless of organic loading rate. And the coulombic efficiency amounted to 22.4~23.4%. The acetic acid used as a fuel was transferred through PEM from the anodic chamber to cathodic chamber. The COD removal rate in ML-MFC were $9.3{\sim}10.1g/m^2{\cdot}d$, which indicated the characteristics of anode had no significant effects on COD removal. Coulombic efficiency were 3.6~3.7 % in both cases of ML-MFC experiments, which were relatively small. It was also observed that the microbial growth in cathodic chamber had an adverse effects on the electricity generation in membraneless MFC.

• The Korean Journal of Malacology
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• v.24 no.1
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• pp.41-50
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• 2008

The histochemical characteristics and ultrastructure of the mantle in the spiny top shell, Batillus cornutus were described using light and electron microscopy. The simple epidermal layer wrapped on the top and bottom of the centrally located connective tissue. And then the epidermal layer were divided into the outer epidermal layer near a shell and the inner epidermal layer closed to the visceral mass. The connective tissue layer was composed of the collagen fiber muscularfiber bundle and hemolymph sinus. Mucous cells in the apical mantle contained acid and neutral mucopolysaccaride, and acidic carboxylated mucopolysaccaride in the mid and marginal mantle. The mantle thickness, epidermal layer thickness and hemolymph sinus area displayed a trend of reduction from the marginal zone to the apical zone. From TEM observation, it was possible to distinguish epithelium, ciliated cell, absorptive cell and secretory cell in the epidermal layer. The epithelia were columnar and the nucleus was elliptical. The free surface were covered with microvilli. The lateral membranes of epithelium was con nected with neighboring cells by the zonular occludens, zonular adherens and membrane interdigitation. Ciliated cell on free surface had cilia and microvilli, and numerous mitochondria in the apical cytoplasm. In the epidermal layer, it observed 2 type cells having absorptive function. The absorptive cells were columnar in shape, and contained microvilli, pinocytotic vesicles, mitochondria and lysosomes of various electron density. Secretory cells can be divided into four types (A, B, C, D) depending on the cell shape and characteristics of secretory granules. These cells were unicellular glands and had similar characteristics to previously reported on the mantle of the gastropod and bivalves.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.31 no.6
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• pp.469-477
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• 2009

Purpose: This study was performed to evaluate the effect of various graft materials used with a titanium cap on the ability of new bone formation in the rabbit calvarium. Materials and Methods: A total of 32 sites of artificial bony defects were prepared on the calvaria of sixteen rabbits by using a trephine bur 8 mm in diameter. Each rabbit had two defect sites. 0.2 mm deep grooves were formed on the calvaria of sixteen rabbits by using a trephine bur 8 mm in diameter for the fixation of a titanium cap. The treatments were performed respectively as follows: without any graft for the control group (n=8), autogenous iliac bone graft for experimental group 1 (n=8), alloplastic bone graft ($SynthoGraft^{(R)}$, USA) for experimental group 2 (n=8), and xenogenic bone graft ($NuOss^{(R)}$, USA) for experimental group 3 (n=8). After the treatments, a titanium cap (8 mm in diameter, 4 mm high, and 0.2 mm thick) was fixed into the groove. At the third and sixth postoperative weeks, rabbits in each group were sacrificed for histological analysis. Results: 1. In gross examination, the surgical sites showed no signs of inflammation or wound dehiscence, and semicircular-shaped bone remodeling was shown both in the experimental and control groups. 2. In histological analysis, the control group at the third week showed bone remodeling along the inner surface of the cap and at the contact region of the calvarium without any specific infiltration of inflammation tissue. Also, there was no soft tissue infiltration. Bone remodeling was observed around the grafted bone and along the inner surface of the titanium cap in experimental group 1, 2, and 3. 3. Histologically, all groups at the sixth week showed the increased area of bone remodeling and maturation compared to those at the third week. In experimental group 2, the grafted bone was partially absorbed by multi nucleated giant cells and new bone was formed by osteoblasts. In group 3, however, resorption of the grafted bone was not observed. 4. Autogenous bone at the third and sixth week showed the most powerful ability of new bone formation. The size of newly formed bone was in decreasing order by autogenous, alloplastic, and heterogenous bone graft. There was no statistically significant difference among autogenous, alloplastic, and heterogenous bones(p>0.05). Summary: This result suggests that autogenous bone is the best choice for new bone formation, but when autogenous bone graft is in limited availability, alloplastic and xenogenic bone graft also can be an alternative bone graft material to use with a suitably guided membrane.

• Korean Journal of Ichthyology
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• v.2 no.2
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• pp.169-181
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• 1990

The development of eggs and larvae, and minute scale-like tubercles on the skin surface of larval Acantlaorhodeus gracilis from Korea were observed. They spawned from late March through the middle of June. A fish spawned at least 5 times and the number of eggs averaged 304 per oviposition. Unfertilized eggs are nearly ovoid-shaped(mean$\pm$SD=$2.09{\pm}0.04\;mm$ in length with range of 2.05 to 2.13 mm and mean$\pm$SD=$1.26{\pm}0.02\;mm$ in breadth with range of 1.24 to 1.30 mm measured for the 50 eggs) and opaque yellow color. The tip of egg membrane at the animal pole side swelled and formed a few hilly projections. The shape of the eggs was just like a loquat. Most of embryos began to hatch out in thirty-eight hours after insemination at $22{\pm}1^{\circ}C$ in water temperature. As regards the morphological characters of the eggs and larval development, Acan. gracilis was similar to Acan. asmussi, Acheilognathus rhombeus, A. longipinnis and Pseudoperilampus typus. The larvae of this species is unique particularly in the following two characters, i.e., 1) scale-like tubercles ellipsoided in a diagonal cross section on the whole body and 2) incessant wiggly movement pattern as that of fly maggot, with the larvae of the above mentioned species. These characters seem to reflect the phylogenetic relationships among acheilognathine fishes. On the other hand, this species and Acan. asmussi are spring-summer spawning bitterlings. And also these species never retard the larval growth in such larval stage as the duration from Stage B to Stage D.