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Bit Chan Kim,Ki Woong Chae,천채일 한국물리학회 2020 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.76 No.3
BaTiO3 ceramics were fabricated at various sintering temperatures by using a conventional solid-oxide reaction method. The ferroelectric properties and the electro-caloric effect (ECE) were investigated as functions of the sintering temperature. The sample had a low density (< 80% of the theoretical value) and a small grain size of about 1.5 μm when the sintering temperature was 1320 °C or lower whereas abnormal grain growth was observed at sintering temperatures above 1320 °C. The density and the matrix grain size increased significantly with increasing sintering temperature above 1320 °C. The P-E hysteresis loop of the sample showed a poor slanted-shape at 1320 °C and was well-saturated at sintering temperatures of 1350 °C and higher. The improvement in the P-E loop, which was obtained by increasing in the sintering temperature, might be caused by an increase in the matrix grain size or the appearance of abnormal grains. The maximum and the remanent polarizations decreased continuously with increasing measurement temperature from 60 °C to 160 °C. A constricted double-hysteresis P-E loop was observed at temperatures just above the Curie temperature (~ 120 °C) due to an electric-field-induced phase transition. The adiabatic temperature change due to the ECE (ΔT_EC) was obtained using an indirect method. The maximum ΔT_EC was obtained just above T_C where the double P-E loop was observed. The sample sintered at 1365 °C showed the highest ΔT_EC and EC strength (|Δ T|/|Δ E|), which were 1.30 °C at 2 kV/mm and 0.65 K·mm/kV, respectively.
Electro-caloric eff ects in the BaTiO 3 -based solid solution ceramics
Bit Chan Kim,Chae Il Cheon 한국세라믹학회 2020 한국세라믹학회지 Vol.57 No.5
Electro-caloric eff ect (ECE) was investigated in BaTiO 3 (BT)-based solid solution ceramics, Ba(Zr,Ti)O 3 (BZT), Ba(Sn,Ti)O 3 (BST) and (Ba,Ca)(Zr,Ti)O 3 (BCZT) with the composition near an invariant critical point (ICP). The samples were fabricated by the solid-state reaction method and the ECE was obtained by an indirect measurement. The 12BZ–88BT, 9BS–91BT, and 32BCT–68BZT samples showed the best polarization–electric fi eld (P–E) hysteresis characteristics at room temperature and displayed dielectric peaks at 46, 58, and 66 °C, which are the Curie temperatures. With increasing temperature, the P–E loops changed from typical ferroelectric square shapes to paraelectric slanted shapes in the BT-based solid solution ceramics. The adiabatic temperature change due to the ECE (Δ T ECE ) showed the maximum values of 0.46 °C at 80 °C, 0.5 °C at 65 °C, and 0.47 °C at 75 °C, respectively, in the 12BZ–88BT, 9BS–91BT, and 32BCT–68BZT samples. The BT-based solid solution ceramics showed smaller maximum ΔT ECE , but broader Δ T ECE peaks at nearer room temperature than the BT ceramic. The enhancement of the ECE due to the multi-phase coexistence was not observed in BT-based solid solutions with the compositions near an invariant critical point (ICP) at which several phases coexist.
( Chan Kwon Park ),( Nahyeon Kang ),( Su Yeon Choi ),( Bit Na Kim ),( Chang Dong Yeo ),( Jin Woo Kim ),( Sang Haak Lee ),( Young Kyoon Kim ),( Dong Soo Lee ),( Tae-jung Kim ),( Seong-beom Lee ),( Sug 대한결핵 및 호흡기학회 2017 대한결핵 및 호흡기학회 추계학술대회 초록집 Vol.124 No.-
A hypoxic microenvironment leads to increase the invasiveness and the metastatic potential of cancer cells within tumors via epithelial- mesenchymal transition (EMT) and cancer stemness acquisition in multiple cancers. However, hypoxia-induced changes in expression and function of candidate stem cell markers and their possible molecular mechanism has not well been understood. Normal and cancerous lung cell lines (BEAS-2B, A549, H292, H226 and H460) were analyzed in normoxic or hypoxic (less than 1% O2) conditions. For screening of changes in expression among stem cell markers, transcriptome analysis using next-generation sequencing was performed by HiSeq 2500 system. For validation, stem cell characteristics were analyzed with RT-PCR, western blotting, immunofluorescence staining, soft agar colony and sphere formation assays, and an in vivo mouse tumor model. EMT was assessed with western blotting, as well as wound healing and Matrigel invasion assays. To determine whether epigenetic mechanism is involved, cell lines were treated with a DNA methyltransferase inhibitor (AZA), and methylation-specific PCR and bisulfite sequencing were performed. Next-generation sequencing revealed CXCR4 expression was significantly increased after hypoxic condition which functionally resulted in EMT and cancer stemness acquisition. The acquisition of EMT and stemness properties was inhibited by treatment with CXCR4 siRNA. CXCR4 was activated by either hypoxic condition and treatment with AZA.
( Chan Kwon Park ),( Sang Hoon Jeon ),( Hyung Woo Kim ),( Nahyeon Kang ),( Bit Na Kim ),( Su Yeon Choi ),( Young Kyoon Kim ),( Seung Joon Kim ),( Mi Sun Park ),( Hyeon Woo Yim ) 대한결핵 및 호흡기학회 2017 대한결핵 및 호흡기학회 추계학술대회 초록집 Vol.124 No.-
Introduction: Recently, target therapy for cancer patients should be considered according to the individual mutational status. Therefore, detection of mutations is clinically important for patients’ outcome. Molecular testing of lung cancer is one of the most important standard of care and treatment. However, it is not always easy to get enough tumor tissue from patients. There is a promising novel mutation detection technology, which is PANA Mutyper. We compared effectiveness of both methods for the detection of KRAS mutation using tumor tissues, cell blocks and pleural effusions with patients with malignant pleural effusion. Methods: KRAS mutations were assessed by PANA Mutyper and PNA clamping using tumor tissues, cell blocks and pleural effusions. The diagnostic usefulness of two methods were analyzed. Results: A total of 104 patients with malignant pleural effusion were enrolled which includes 56 adenocarcinoma of lung, 11 squamous carcinoma of lung, 17 small cell lung cancer, 3 large cell lung cancer, 3 stomach cancer, 2 ovary cancer, etc. PANA Mutyper showed more superior detection rate than PNA clamping through tumor tissues, cell blocks and pleural effusions. Conclusion: PANA Mutyper had a diagnostic superiority for the detection of KRAS mutations in patients with malignant pleural effusion. This method can be used as more sensitive and accurate detection of KRAS mutations.
( Chang Dong Yeo ),( Nahyeon Kang ),( Su Yeon Choi ),( Bit Na Kim ),( Chan Kwon Park ),( Jin Woo Kim ),( Young Kyoon Kim ),( Seung Joon Kim ) 대한내과학회 2017 The Korean Journal of Internal Medicine Vol.32 No.4
A hypoxic microenvironment leads to cancer progression and increases the metastatic potential of cancer cells within tumors via epithelial-mesenchymal transition (EMT) and cancer stemness acquisition. The hypoxic response pathway can occur under oxygen tensions of < 40 mmHg through hypoxia-inducible factors (HIFs), which are considered key mediators in the adaptation to hypoxia. Previous studies have shown that cellular responses to hypoxia are required for EMT and cancer stemness maintenance through HIF-1α and HIF-2α. The principal transcription factors of EMT include Twist, Snail, Slug, Sip1 (Smad interacting protein 1), and ZEB1 (zinc finger E-box-binding homeobox 1). HIFs bind to hypoxia response elements within the promoter region of these genes and also target cancer stem cell-associated genes and mediate transcriptional responses to hypoxia during stem cell differentiation. Acquisition of stemness characteristics in epithelial cells can be induced by activation of the EMT process. The mechanism of these phenotypic changes includes epigenetic alterations, such as DNA methylation, histone modification, chromatin remodeling, and microRNAs. Increased expression of EMT and pluripotent genes also play a role through demethylation of their promoters. In this review, we summarize the role of hypoxia on the acquisition of EMT and cancer stemness and the possible association with epigenetic regulation, as well as their therapeutic applications.
Choi Wook Jin,Cho Young Soon,Ha Young Rock,Oh Je Hyeok,Lee Heekyung,Kang Bo Seung,Kim Yong Won,Koh Chan Young,Lee Ji Han,Jung Euigi,Sohn Youdong,Kim Han Bit,Kim Su Jin,Kim Hohyun,Suh Dongbum,Lee Dong 대한응급의학회 2023 Clinical and Experimental Emergency Medicine Vol.10 No.4
Point-of-care ultrasound (POCUS) is a rapidly developing technology that has the potential to revolutionize emergency and critical care medicine. The use of POCUS can improve patient care by providing real-time clinical information. However, appropriate usage and proper training are crucial to ensure patient safety and reliability. This article discusses the various applications of POCUS in emergency and critical care medicine, the importance of training and education, and the future of POCUS in medicine.