• Journal of Physiology & Pathology in Korean Medicine
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• v.22 no.2
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• pp.422-426
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• 2008

In this study, the preventive effects of Radix Trichosanthis extracts (RTE) against cytokine-induced ${\beta}-cell$ death were assessed. Cytokines generated by immune cells infiltrating pancreatic islets are crucial mediators of ${\beta}-cell$ destruction in insulin-dependent diabetes mellitus. The treatment of RIN cells with $interleukin-1{\beta}$ ($IL-1{\beta}$) and $interferon-{\gamma}$ ($IFN-{\gamma}$) resulted in a reduction of cell viability. RTE protected $IL-1{\beta}$ and $IFN-{\gamma}$-mediated viability reduction in a concentration-dependent manner. Incubation with RTE also induced a significant suppression of $IL-1{\beta}$ and $IFN-{\gamma}$-induced inducible nitric oxide synthase (iNOS) protein expression. The molecular mechanism by which RTE inhibited iNOS protein expression appeared to involve the inhibition of $NF{-\kappa}B$ activation. The $IL-1{\beta}$ and $IFN-{\gamma}$-stimulated RIN cells showed increases in $NF{-\kappa}B$ binding activityand $I{\kappa}B{\alpha}$ degradation in cytosol compared to unstimulated cells. However, pretreatment with RTE inhibited cytokines-induced $I{\kappa}B{\alpha}$ degradation and $NF{-\kappa}B$ activation in RINm5F cells. Furthermore, the protective effects of RTE were verified via protection of impairment in glucose-stimulated insulin secretions in $IL-1{\beta}$ and $IFN-{\gamma}$-treated islets.

• Applied Microscopy
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• v.40 no.2
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• pp.81-88
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• 2010

The fine structural characteristics of the apoptotic cells in the cutaneous epithelium of the anuran tadpole of the black-spotted frog, Rana nigromaculata was examined using the TUNEL (Terminal deoxynucleotidyl transferase-mediated biotinylated d-Uridine triphosphate Nick End Labeling) staining technique and TEM (transmission electron microscopy) observations. The cutaneous epithelium of the tadpole was composed of stratified cuboidal cells and the apoptotic cell death was observed continuously during the tail degeneration stages from the Shumway stage number 31 to 33. The early apoptotic cells shown in the epithelium demonstrated condensation and margination of the chromatin material at the nuclear periphery, and nuclear breakdown and cytoplasmic condensation were followed. Subsequent cytoplasmic degeneration of the apoptotic cell were produced by membrane-bounded cell fragments with relatively well preserved organelles. Following the processes of autophagic degradation, the late apoptotic cells being phagocytosed by other surrounding cells. These nearby cells, presumptive intraepithelial macrophages, contain a variety of lysosomal residual bodies which fuses with other cell organelles or other cytoplasmatic material to form secondary lysosomes. They are soon transformed into lamellar shaped vesicles and finally disappeared during the process of degradation.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.11 no.11
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• pp.5301-5323
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• 2017

Small cell deployment offers a low-cost solution for the boosted traffic demand in heterogeneous cellular networks (HCNs). Besides improved spatial spectrum efficiency and energy efficiency, future HCNs are also featured with the trend of network architecture convergence and feasibility for flexible mobile applications. To achieve these goals, dual connectivity (DC) is playing a more and more important role to support control/user-plane splitting, which enables maintaining fixed control channel connections for reliability. In this paper, we develop a tractable framework for the downlink SINR analysis of DC assisted HCN. Based on stochastic geometry model, the data-control joint coverage probabilities under multi-frequency and single-frequency tiering are derived, which involve quick integrals and admit simple closed-forms in special cases. Monte Carlo simulations confirm the accuracy of the expressions. It is observed that the increase in mobility robustness of DC is at the price of control channel SINR degradation. This degradation severely worsens the joint coverage performance under single-frequency tiering, proving multi-frequency tiering a more feasible networking scheme to utilize the advantage of DC effectively. Moreover, the joint coverage probability can be maximized by adjusting the density ratio of small cell and macro cell eNBs under multi-frequency tiering, though changing cell association bias has little impact on the level of the maximal coverage performance.

• Membrane Journal
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• v.33 no.3
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• pp.127-136
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• 2023

In this study, the electrochemical performance of a 5-layer fuel cell stack using silica composite membranes as polymer electrolyte membranes was evaluated. It was observed that the flow rate of the fuel gases plays a crucial role in stack performance, particularly being mainly dependent on the flow rate of hydrogen. Increasing the flow rate of oxygen resulted in negligible changes in performance, whereas an increase in the flow rate of hydrogen demonstrated performance improvements. However, this led to an imbalance in the ratio of hydrogen to oxygen flow rates, causing significant degradation in stack performance and durability. A decline in stack performance was also observed over time due to the degradation of stack components. This phenomenon was consistently observed in individual unit cells. Based on these findings, it was emphasized that, in addition to optimizing the performance of each component during stack operation, it is important to optimize design and operating conditions for uniform flow rate control. Lastly, the developed silica composite membrane was assessed to have sufficient performance for application in actual fuel cell systems, exhibiting a performance of over 25 W based on maximum power.

• Journal of the Microelectronics and Packaging Society
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• v.27 no.4
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• pp.55-60
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• 2020

The PERC photovoltaic (PV) modules installed in PV power plant are still reports potential-induced degradation (PID) degradation due to high voltage potential differences. This is because Na+ ions in the cover glass of PV modules go through the encapsulant (EVA) and transferred to the surface of solar cells. As positive charges are accumulated at the ARC (SiOx/SiNx) interface where many defects are distributed, shunt-resistance (Rsh) is reduced. As a result, the leakage current is increased, and decrease in solar cell's power output. In this study, to prevent of this phenomenon, a Moth-eye nanostructure was deposited on the rear surface of an optical film using Nano-Imprint Lithography method, and a solar mini-module was constructed by inserting it between the cover glass and the EVA. To analyze the PID phenomenon, a cell-level PID acceleration test based on IEC 62804-1 standard was conducted. Also analyzed power output (Pmax), efficiency, and shunt resistance through Light I-V and Dark I-V. As a result, conventional solar cells were decreased by 6.3% from the initial efficiency of 19.76%, but the improved solar cells with the Moth-eye nanostructured optical film only decreased 0.6%, thereby preventing the PID phenomenon. As of Moth-eye nanostructured optical film, the transmittance was improved by 4%, and the solar module output was improved by 2.5%.

• Journal of Microbiology and Biotechnology
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• v.33 no.9
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• pp.1206-1212
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• 2023

The Wnt/β-catenin pathway plays essential roles in regulating various cellular behaviors, including proliferation, survival, and differentiation [1-3]. The intracellular β-catenin level, which is regulated by a proteasomal degradation pathway, is critical to Wnt/β-catenin pathway control [4]. Normally, casein kinase 1 (CK1) and glycogen synthase kinase-3β (GSK-3β), which form a complex with the scaffolding protein Axin and the tumor suppressor protein adenomatous polyposis coli (APC), phosphorylate β-catenin at Ser45, Thr41, Ser37, and Ser33 [5, 6]. Phosphorylated β-catenin is ubiquitinated by the β-transducin repeat-containing protein (β-TrCP), an F-box E3 ubiquitin ligase complex, and ubiquitinated β-catenin is degraded via a proteasome pathway [7, 8]. Colorectal cancer is a significant cause of cancer-related deaths worldwide. Abnormal up-regulation of the Wnt/β-catenin pathway is a major pathological event in intestinal epithelial cells during human colorectal cancer oncogenesis [9]. Genetic mutations in the APC gene are observed in familial adenomatous polyposis coli (FAP) and sporadic colorectal cancers [10]. In addition, mutations in the N-terminal phosphorylation motif of the β-catenin gene were found in patients with colorectal cancer [11]. These mutations cause β-catenin to accumulate in the nucleus, where it forms complexes with transcription factors of the T-cell factor/lymphocyte enhancer factor (TCF/LEF) family to stimulate the expression of β-catenin responsive genes, such as c-Myc and cyclin D1, which leads to colorectal tumorigenesis [12-14]. Therefore, downregulating β-catenin response transcription (CRT) is a potential strategy for preventing and treating colorectal cancer. Plant cytokinins are N⁶-substituted purine derivatives; they promote cell division in plants and regulate developmental pathways. Natural cytokinins are classified as isoprenoid (isopentenyladenine, zeatin, and dihydrozeatin), aromatic (benzyladenine, topolin, and methoxytopolin), or furfural (kinetin and kinetin riboside), depending on their structure [15, 16]. Kinetin riboside was identified in coconut water and is a naturally produced cytokinin that induces apoptosis and exhibits antiproliferative activity in several human cancer cell lines [17]. However, little attention has been paid to kinetin riboside's mode of action. In this study, we show that kinetin riboside exerts its cytotoxic activity against colon cancer cells by suppressing the Wnt/β-catenin pathway and promoting intracellular β-catenin degradation.

• Journal of Photoscience
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• v.9 no.2
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• pp.213-216
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• 2002

Skin pigmentation, also known as complexion coloration, results from the biosynthesis of melanin within the melanocytes of the Stratum basalum and the subsequent transfer, translocation, and degradation of this pigment to, in, and by the neighboring keratinocytes respectively, Melanins are produced and retained in melanosomes synthesized in the cell body that are translocated along the dendrites using microtubules via motor proteins. Melanosomes are eventually captured and retained at the tips of dendrites by attachment to the peripherally localized actin. Melanosomes reaching the dendritic tips are transferred to keratinocytes, primarily via phagocytosis of released melanosomes by keratinocytes. Molecules responsible for cell/cell recognition and interaction that regulate transfer are being identified. Some of these putative mediators appear to be affected by ultraviolet radiation. After the keratinocytes receive melanosomes, the granules are distributed individually or as clusters in dark versus light skin respectively. These melanosomes are then aggregated over the nucleus for photoprotection ofkeratinocyte DNA and eventually degraded.

• Current Photovoltaic Research
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• v.4 no.3
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• pp.98-107
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• 2016

Third-generation photovoltaics are of low cost based on solution processes and are targeting a high efficiency. To meet the commercial demand, however, significant improvements of both efficiency and stability are required. In this sense, interfacial engineering can be useful key to solve these issues because trap sites and interfacial energy barrier and/or chemical instability at organic/organic and organic/inorganic interfaces are critical factors of efficiency and stability degradation. Here, we thoroughly review the interfacial engineering strategies applicable to three representative third-generation photovoltaics - organic, perovskite, colloidal quantum dot solar cell devices.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1997.04a
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• pp.249-252
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• 1997

Electroluminescence(EL) devices based on organic thin layers have attracted lot of interests because of their possible application as large-area display-emitting display. One of the problems of such devices is lifetime of the cell, where the degradation of the cell is partially due to the crystalliyzation of organic layers. In large part, this problem can be solved by using a multilayer device structure prepared by vapor deposition technique. In this study, blue light-emitting multilayer organic electroluminescence devices were fabricated vsing Poly (9-vinylcarbaEole) (PVK) and 2- (4-tert-butylphenyl)-5-(4$^{#}$-bis-phenyl) 1,3,4-oxadiazole (PBO) as hole trasport and electron transport material, respectively, where trim(8-hyd roxyquinolinate) aluminum (Al $q_3$) was used as a luminescenct material. A cell structure of glass sub- strate/indume-tin-oxide(ITO)/PCK/Al $q_3$/PBD/Mg:In was employed. Blue emission peak at 510nm was observed with this cell structure.e.

• CELLMED
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• v.7 no.1
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• pp.3.1-3.2
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• 2017

The efficient removal of dead cells is an evolutionarily conserved process essential for homeostasis in multicellular organisms. The phagocytosis involves a series of steps that ultimately leads the detection of apoptotic cell by the phagocytes and the subsequent engulfment and degradation of corpse. The uptake of apoptotic cells by phagocytes not only removes debris from tissues but also generates an anti-inflammatory signal that blocks tissue inflammation. Conversely, impaired clearance of dead cells can cause loss of immune tolerance and the development of various inflammation-associated diseases such as autoimmunity, but can also affect cancer development. This review will discuss current understanding of the molecular mechanism of apoptotic cell phagocytosis and how they may be related to human diseases.