펄스레이저 증착법에 의한 Al₂O₃ 입자 표면 위 TiO₂ 나노입자의 코팅

최봉근,김소연,박철우,박재화,홍윤표,심광보,Choi, Bong Geun,Kim, So Yeon,Park, Cheol Woo,Park, Jae Hwa,Hong, Yoon Pyo,Shim, Kwang Bo 한국결정성장학회 2013 한국결정성장학회지 Vol.23 No.4

Titanium dioxides nanoparticles coated aluminum oxide powders were fabricated by pulsed laser deposition (PLD) with Nd : YAG laser at 266 nm. The Pulse laser energy is 100 mJ/pulse. During the irradiation of the focused laser on the $TiO_2$ target, Ar gas is supplied into the chamber. The gas pressure is varied in a range of $1{\times}10^{-2}$ to 100 Pa. Titanium dioxides nanoparticles deposited aluminum oxide powders were characterized by using energy dispersive X-ray spectroscopy (EDX), high resolution transmission electron microscopy (HR-TEM), in order to understand the effect of Ar background gas on surface morphology and properties of the powders. The coated $TiO_2$ nanoparticles had nanosized spherical shape and the crystallite sizes of 10~30 nm. The morphology of coated $TiO_2$ nanoparticles is not affected by gas pressure. However, the particle size and crystallinity slightly increased with the increase of gas pressure. According to this technique, the size and crystallinity of nanoparticles can be easily controlled by controlling pressure during the laser irradiation.

미성숙 희쥐 해마에서 열성경련에 의한 신경흥분성의 증가

최봉근,배혜란*,황규근 대한소아청소년과학회 2004 Clinical and Experimental Pediatrics (CEP) Vol.47 No.9

Purpose:To determine whether febrile seizure enhances neuroexcitability by altering synaptic transmission and whether febrile seizure-induced hyperexcitability leads to long-lasting neuronal death. Methods:We investigated the expression of synaptic and postsynaptic proteins and the apoptosis of neuronal cells in rat pup hippocampus after hyperthermic seizure using immunoblotting and confocal microscopy. Results:Hyperthermic seizure enhanced the long-term expressions of presynaptic proteins such as syntaxin, VAMP, SNAP-25 and nSec1, whereas that of NSF was decreased. The expressions of postsynaptic NMDA receptors 1, 2a and 2b were up-regulated. The expression of postsynaptic AMPA glutamate receptors 1 month after hyperthermic seizures altered by way of increasing the ratio of GluR1 to GluR2 and decreasing NSF-GluR2 interaction, which leads to the formation of Ca2+ permeable AMPA receptors and enhanced toxicity. However, in spite of enhanced neuroexcitability, there was a transient increase of neuronal death in hipocampus one week after hyperthermic seizure, but returned to baseline one month later. Conclusion:These results demonstrate both presynaptic and postsynaptic forms of long-term enhancement of glutamate synaptic transmission after hyperthermic seizure and support the idea that early-life febrile seizure might have persistent effects on neuronal excitability in the hippocampus. 목 적:열성경련은 영유아에서 가장 흔한 경련이다. 열성경련이 지속적인 신경 흥분성을 유발하는지와 열성경련이 측두엽 간질과 연관성이 있는지가 중요한 관심사이다. 이에 미성숙 쥐 모델을 이용하여 열성경련이 해마의 시냅스 단백질 및 glutamate 수용체 발현에 미치는 효과를 관찰하여 신경 흥분성과 신경세포 손상을 유발하는지 알아보고자 이 연구를 시도하였다. 방 법:실험동물로는 생후 10일된 Sprague-Dawley계의 rat pups 흰쥐를 사용하였다. 열성경련은 더운물 (47℃)로 유발시켰다. 경련 유발 후 생후 1일째, 1주째, 1개월째 뇌를 적출하여 western blot를 이용하여 해마에서 시냅스 단백의 발현을 조사하였으며 tunel study로 해마 신경세포의 세포사를 관찰하였다. 결 과:열성경련을 유발시킨 쥐의 해마에서 고체온만 유발시킨 대조군에 비해 신경 연접부 세포막과 연접소포의 융합에 관여하는 시냅스 단백질인 VAMP, SNAP-25, syntaxin 및 nSec1의 발현이 경련 한달 후까지 증가되었으나, NSF의 발현은 감소되었다. 열성경련 후 시냅스 후 신경막에 있는 NMDA 수용체 1, 2a 및 2b의 발현은 증가하였다. AMPA 수용체 중 GluR1의 발현은 열성경련 후 증가된 반면 GluR2의 발현은 감소되었다. 시냅스 후 신경막의 GluR2의 수를 증가시키는 것으로 알려진 NSF와 GluR2의 수를 증가시키는 것으로 알려진 NSF와 GluR2 복합체의 형성이 열성경련 한 달 후까지 현저히 감소되어 있는 것을 관찰하였다. TUNEL 염색으로 관찰한 신경세포의 손상은 열성경련 일주일 후에는 유의한 증가를 보였으나 한 달 후에는 유의한 차이가 없었다 결 론:열성경련은 시냅스 전 시냅스단백질의 발현을 증가시키고, 시냅스 후 신경막에서 GluR1/GluR2 발현비를 증가시킬 뿐만 아니라, GluR2와 NSF의 결합을 감소시킴으로써 Ca2+ permeable AMPA 수용체 형성을 증가시킴으로써 신경흥분성이 유발되는 것으로 보인다.

건강한 젖소, 발굽건강부터 챙기자

최봉근,Choe, Bong-Geun 한국낙농육우협회 2017 낙농·육우 Vol.37 No.4

Polymorphisms of TGFBR2 contribute to the progression of papillary thyroid carcinoma

최봉근,김수강,박해정,박현경,권기환,임성훈,임성빈 대한독성 유전단백체 학회 2012 Molecular & cellular toxicology Vol.8 No.1

Transforming growth factor, beta receptor II (70/80 kDa) (TGFBR2) is a tumor suppressor. Mutations in the TGFBR2 gene appear to have an increased risk of developing several cancers. To investigate whether TGFBR2 polymorphisms are associated with the development of papillary thyroid carcinoma (PTC),three single nucleotide polymorphisms (SNPs) of TGFBR2 (rs764522, -1444C/G; rs3087465, -834G/A;rs2228048, Asn389Asn) were selected and genotyped by direct sequencing in 92 PTC patients and 330 control subjects. We also assessed the relationships between three SNPs of TGFBR2 and clinicopathologic characteristics of PTC such as size (⁄1 cm and ›1cm), number (unifocality and multifocality), location (one lobe and both lobe), extrathyroidal invasion, and lymph node metastasis. SNPStats and Haploview version 4.2 were used to analyze genetic data. Multiple logistic regression models (codominant1, codominant2,dominant, recessive, overdominant, and log-additive)were performed to calculate odds ratios (ORs), 95%confidence intervals (CIs), and P values. The three examined SNPs were not associated with PTC. In clinicopathologic characteristics, two promoter SNPs (rs3087465 and rs764522) were associated with lymph node metastasis (rs3087465, P=0.009 in the codominant1model, P=0.043 in the dominant model, P=0.003 in the overdominant model; rs764522, P=0.021in the codominant1 model, P=0.044 in the dominant model, P=0.016 in the overdominant model). The synonymous SNP rs2228048 was associated with extrathyroidal invasion (P=0.024 in the dominant model,P=0.015 in the log-additive model). The allele frequency of rs2228048 was significantly different between PTC with extrathyroidal invasion and PTC without extrathyroidal invasion (P=0.018, OR=0.46, 95% CI=0.24-0.88). These results suggest that TGFBR2 may be associated with the progression of PTC in Korean population.

Al 용탕 중의 수소함량이 주물의 미세기공에 미치는 영향

최봉근,박순 울산대학교 2002 공학연구논문집 Vol.33 No.1

Al 주물의 기공발생 원인을 이론적으로 규명하고, Al 용탕 중의 수소함량을 직접 측정하여 탈가스의 효과와 주물품의 미세조직변화를 관찰하였다. 그 결과, 다이캐스팅용 합금으로 많이 사용되는 Al-7.5%Si-0.4%Mg 합금에서 기공이 전혀 발생하지 않을 용탕 중의 최소수소농도는 0.1㎤/100g이며, 용탕 중의 수소는 장입물 속의 수분에 의해서라기 보다는 주로 용해 중의 분위기로부터 침투한다는 사실을 알았다. 또한 탈가스 효과는 초기 수소농도가 높을수록, 용탕의 온도가 낮을수록 더 좋다는 결론을 얻었다. We studied theoretically the formation of porosities in Al castings, and observered by experimentally the hydrogen contents in Al melts and the changes of microstructures in Al castings. As results, we know that the minimun hydrogen content which will not generate the porosity in Al-7.5%Si-0.4%Mg diecasting alloy is 0.1㎤/100g and, the hydrogen penetrates into the Al melts by the melting atmospheres rather than by the moistures in Al scrap. Also, we know the facts that the initial hydrogen contents are higher and the temperature of melts are lower, the effect of degassing is supenor.

RF-PECVD법에 의해 증착된 DLC 박막의 결합구조와 기계적 특성에 관한 보조가스의 영향

최봉근,Choi, Bong-Geun 한국결정성장학회 2015 한국결정성장학회지 Vol.25 No.4

In this work, we were investigated the effect of the additive gases on the relationship between bonding structure and mechanical properties of the deposited films when the DLC films were deposited on Si-wafer by the rf-PECVD method with the addition of small amounts of carbon dioxide and nitrogen to the mixture gas of methane and hydrogen. The deposition rate of the films increased as the rf-power increased, while it decreased with increasing the amount of additive gases. Also, as the carbon dioxide gas increased, the hydrogen content in the films decreased but the $sp^3/sp^2$ ratio of the films increased. In case of nitrogen gas, the hydrogen content decreased, however the $sp^3/sp^2$ ratio and nitrogen gas flow rate did not show a specific tendency.

알쯔하이머의 고찰

최봉근,Choe, Bong-Keun 한국생명보험의학회 2004 保險醫學會誌 Vol.23 No.-

너만을 위한 1000일 이벤트, 기다려~봐!

최봉근 샘터사 2003 월간 샘터 Vol.34 No.12

Downregulation of regenerating islet-derived 3 alpha (REG3A)in primary human gastric adenocarcinomas

최봉근,Woo-Ho Kim,Laurence Christa,Paris Descartes),Joobae Park,Chang-Dae Bae 생화학분자생물학회 2007 Experimental and molecular medicine Vol.39 No.6

Gastric carcinoma is considered to be one of the most prevalent cancers worldwide. We have performed differential- display polymerase chain reaction (DD-PCR) in order to compare the gene expression profile of gastric carcinoma and that of a normal stomach, in an attempt to identifiy differentially expressed genes associated with primary human gastric cancers. One of the down-regulated genes in gastric cancers was identified as regenerating islet-derived 3 alpha (REG3A), also known as hepatocarcinoma-intestine-pancreas/ pancreatitis-associated protein (HIP/PAP). REG3A exhibited relatively high expression levels in normal gastric mucosa. However, REG3A was found to be down-regulated in 67% (20 out of 30 samples) of primary human gastric cancers, as determined by RT-PCR. In addition, REG3A mRNA expression was not detected in stomach cancer cell lines, SNU cells. Immunohistochemical analysis further confirmed the down-regulation of REG3A expression in primary human gastric cancers. Treatment with the demethylating agent, 5-aza-2'-deoxycytidine (5-Aza-dC) resulted in the restoration of REG3A mRNA expression in the gastric cancer cell line, indicating that the transcriptional silencing of REG3A in SNU cell lines was caused by DNA methylation. Taken together, these data indicate that REG3A is down-regulated in most primary human gastric cancer cells, and might be useful in the diagnosis of gastric cancer. Further characterization of the differentially expressed gene, REG3A, should lead to a better understanding of the changes occurring at the molecular level during the development and progression of primary human gastric cancer.

막접촉기 개발을 위한 DIPA, MDEA 혼합 아민 수용액의 이산화탄소 용해도 실험 및 모델링

최봉근,김승모,신범주,문지훈,문종호 한국막학회 2020 한국막학회 총회 및 학술발표회 Vol.2020 No.08