• Applied Science and Convergence Technology
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• 제27권5호
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• pp.95-99
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• 2018

We discuss the structural and optical characteristics of GaN nanowires (NWs) grown on Si(111) substrates by a plasma-assisted molecular-beam epitaxy. The GaN NWs with high crystal quality were formed by adopting a new growth approach, so called Ga pre-deposition (GaPD) method. In the GaPD, only Ga was supplied without nitrogen flux on a SiN/Si surface, resulting in the formation of Ga droplets. The Ga droplets were used as initial nucleation sites for the growth of GaN NWs. The GaN NWs with the average heights of 60.10 to 214.62 nm obtained by increasing growth time. The hexagonal-shaped top surfaces and facets were observed from the field-emission electron microscope images of GaN NWs, indicating that the NWs have the wurtzite (WZ) crystal structure. Strong peaks of GaN (0002) corresponding to WZ structures were also observed from double crystal x-ray diffraction rocking curves of the NW samples. At room temperature, free-exciton emissions were observed from GaN NWs with narrow linewidth broadenings, indicating to the formation of high-quality NWs.

• BMB Reports
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• 제56권11호
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• pp.600-605
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• 2023

Intrahepatic cholangiocarcinoma (ICC) is a bile duct cancer and a rare malignant tumor with a poor prognosis owing to the lack of an early diagnosis and resistance to conventional chemotherapy. A combination of gemcitabine and cisplatin is the typically attempted first-line treatment approach. However, the underlying mechanism of resistance to chemotherapy is poorly understood. We addressed this by studying dynamics in the human ICC SCK cell line. Here, we report that the regulation of glucose and glutamine metabolism was a key factor in overcoming cisplatin resistance in SCK cells. RNA sequencing analysis revealed a high enrichment cell cycle-related gene set score in cisplatin-resistant SCK (SCK-R) cells compared to parental SCK (SCK WT) cells. Cell cycle progression correlates with increased nutrient requirement and cancer proliferation or metastasis. Commonly, cancer cells are dependent upon glucose and glutamine availability for survival and proliferation. Indeed, we observed the increased expression of GLUT (glucose transporter), ASCT2 (glutamine transporter), and cancer progression markers in SCK-R cells. Thus, we inhibited enhanced metabolic reprogramming in SCK-R cells through nutrient starvation. SCK-R cells were sensitized to cisplatin, especially under glucose starvation. Glutaminase-1 (GLS1), which is a mitochondrial enzyme involved in tumorigenesis and progression in cancer cells, was upregulated in SCK-R cells. Targeting GLS1 with the GLS1 inhibitor CB-839 (telaglenastat) effectively reduced the expression of cancer progression markers. Taken together, our study results suggest that a combination of GLUT inhibition, which mimics glucose starvation, and GLS1 inhibition could be a therapeutic strategy to increase the chemosensitivity of ICC.

• Clinical and Experimental Pediatrics
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• 제49권10호
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• pp.1079-1085
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• 2006

목 적 : 본 연구는 다양한 소아 고위험 고형종양에서 이식된 조혈모세포의 수와 조혈기능의 회복속도 나아가 감염과의 상관관계에 대해 분석함으로써 자가 조혈모세포이식에서 안전한 이식을 위해 필요한 최소한의 조혈모세포의 수가 어느 정도인지를 알아보고자 하였다. 방 법 : 2004년 1월부터 2005년 12월까지 2년 동안 삼성서울병원 소아과에서 소아 고형종양을 대상으로 시행된 고용량 화학요법 후 자가 말초혈 조혈모세포이식 72례에서 이식된 조혈모세포의 수와 이식 후 혈액학적 회복속도 및 감염과의 관계를 후향적으로 분석하였다. 결 과 : 중성구 회복속도에 독립적으로 영향을 주는 유일한인자는 이식된 CD34 양성세포의 수였고 혈소판 회복속도에 독립적으로 영향을 주는 인자는 이식된 CD34 양성세포의 수와 이식 전 치료기간이었다. 미생물학적으로 확인된 감염의 빈도는 이식된 CD34 양성세포 수 등 여러 인자와 관련성이 없었다. 나이가 어릴수록, 이식 전 치료기간이 길수록, TBI 혹은 thiotepa가 포함된 고용량 화학요법, 설사가 심한 경우, 이식된 CD34 양성세포의 수가 적은 경우($2{\times}10^6/kg$ 이하) 발열기간이 유의하게 길었다. 그러나 미생물학적으로 확인된 감염의 빈도는 이러한 발열에 영향을 주는 여러 인자와 관련성이 없었다. 이식된 CD34 양성세포의 수를 보다 세분하여 중성구 및 혈소판 회복속도, 고열 지속기간 및 항생제 사용기간을 비교하였을 때 이식된 CD34 양성세포의 수가 적을수록 중성구 및 혈소판 회복속도가 늦어지고 항생제 사용기간이 길어졌으나 고열 지속 기간에는 통계적으로 유의한 차이가 없었다. 결 론 : 이식된 CD34 양성세포의 수에 따라 조혈기능의 회복속도는 분명한 차이가 있지만 미생물학적으로 확인된 감염의 빈도 혹은 임상적으로 유의한 고열 지속기간의 차이는 없었다. 따라서 고용량 화학요법 후 자가 조혈모세포이식 시 가능한 많은 수의 조혈모세포를 이식하는 것이 바람직하지만 임상적으로 충분한 조혈모세포를 채집하지 못한 경우, 1회 이식 시 최소한 $1{\times}10^6/kg$ 이상인 경우에는 임상적으로 수용할 수 있는 생착이 가능하므로 추가적인 조혈모세포 채집을 위해 고용량 화학요법의 적절한 시기를 놓치지 않는 것이 중요할 것으로 사료된다.

• Applied Science and Convergence Technology
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• 제26권5호
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• pp.118-128
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• 2017

The scope of this work is to determine and compare the effect of electron temperature ($T_e$) and number density ($N_e$) on the yield rate and concentration of reactive chemical species ($^{\bullet}OH$, $H_2O_2$ and $O_3$) in an argon, air and oxygen injected negative DC (0-4 kV) capillary discharge with water flow(0.1 L/min). The discharge was created between tungsten pin-to pin electrodes (${\Phi}=0.5mm$) separated by a variable distance (1-2 mm) in a quartz capillary tube (2 mm inner diameter, 4 mm outer diameter), with various gas injection rates (100-800 sccm). Optical emission spectroscopy (OES) of the hydrogen Balmer lines was carried out to investigate the line shapes and intensities as functions of the discharge parameters such as the type of gas, gas injection rate and inter electrode gap distances. The intensity ratio method was used to calculate $T_e$ and Stark broadening of Balmer ${\beta}$ lines was adopted to determine $N_e$. The effects of $T_e$ and $N_e$ on the reactive chemical species formation were evaluated and presented. The enhancement in yield rate of reactive chemical species was revealed at the higher electron temperature, higher gas injection rates, higher discharge power and larger inter-electrode gap. The discharge with oxygen injection was the most effective one for increasing the reactive chemical species concentration. The formation of reactive chemical species was shown more directly related to $T_e$ than $N_e$ in a flowing water gas injected negative DC capillary discharge.

• Applied Science and Convergence Technology
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• 제27권1호
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• pp.9-13
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• 2018

Samples of anodic oxide film used in semiconductor and display manufacturing processes were prepared at different electrolyte temperatures to investigate the corrosion resistance. The anodic oxide film was grown on aluminum alloy 6061 by using a sulfuric acid ($H_2SO_4$) electrolyte of 1.5 M at $0^{\circ}C$, $5^{\circ}C$, $10^{\circ}C$, $15^{\circ}C$, and $20^{\circ}C$. The insulating properties of the samples were evaluated by measuring the breakdown voltage, which gradually increased from 0.43 kV ($0^{\circ}C$) to 0.52 kV ($5^{\circ}C$), 1.02 kV ($10^{\circ}C$), and 1.46 kV ($15^{\circ}C$) as the electrolyte temperature was increased from $0^{\circ}C$ to $15^{\circ}C$, but then decreased to 1.24 kV ($20^{\circ}C$). To evaluate the erosion of the film by fluorine plasma, the plasma erosion and the contamination particles were measured. The plasma erosion was evaluated by measuring the breakdown voltage after exposing the film to $CF_4/O_2/Ar$ and $NF_3/O_2/Ar$ plasmas. With exposure to $CF_4/O_2/Ar$ plasma, the breakdown voltage of the film slightly decreased at $0^{\circ}C$, by 0.41 kV; however, the breakdown voltage significantly decreased at $20^{\circ}C$, by 0.83 kV. With exposure to $NF_3/O_2/Ar$ plasma, the breakdown voltage of the film slightly decreased at $0^{\circ}C$, by 0.38 kV; however, the breakdown voltage significantly decreased at $20^{\circ}C$, by 0. 77 kV. In addition, for the entire temperature range, the breakdown voltage decreased more when sample was exposed to $NF_3/O_2/Ar$ plasma than to $CF_4/O_2/Ar$ plasma. The decrease of the breakdown voltage was lower in the anodic oxide film samples that were grown slowly at lower temperatures. The rate of breakdown voltage decrease after exposure to fluorine plasma was highest at $20^{\circ}C$, indicating that the anodic oxide film was most vulnerable to erosion by fluorine plasma at that temperature. Contamination particles generated by exposure to the $CF_4/O_2/Ar$ and $NF_3/O_2/Ar$ plasmas were measured on a real-time basis. The number of contamination particles generated after the exposure to the respective plasmas was lower at $5^{\circ}C$ and higher at $0^{\circ}C$. In particular, for the entire temperature range, about five times more contamination particles were generated with exposure to $NF_3/O_2/Ar$ plasma than for exposure to $CF_4/O_2/Ar$ plasma. Observation of the surface of the anodic oxide film showed that the pore size and density of the non-treated film sample increased with the increase of the temperature. The change of the surface after exposure to fluorine plasma was greatest at $0^{\circ}C$. The generation of contamination particles by fluorine plasma exposure for the anodic oxide film prepared in the present study was different from that of previous aluminum anodic oxide films.