오스테나이트계 Fe-25Mn-Al-0.5C 강의 피로성질에 미치는 Al 첨가의 영향

도정호,권숙인,전채홍 한국열처리공학회 1998 熱處理工學會誌 Vol.11 No.4

The effect of Al addition on the fatigue properties of austenitic Fe-25Mn-Al-0.5C steels was studied. When Al was not added to the Fe-25Mn 0.5C steel. the strain induced ε martensites, deformation twins and slip bands were formed during fatigue deformation. When 2wt% of Al was added to the steel, the deformation twins and slip bands were formed during fatigue deformation. When 5wt% of Al was added, only slip bands were formed. In low cycle fatigue test, the alloys containing 0wt% and 2wt%Al showed the cyclic hardening due to ε martensites and deformation twins, resulting in shorter fatigue lives than the alloy containing 5wt%Al. In fatigue crack propagation test, the alloy without Al showed the highest crack propagation rate. The fracture surface of the alloy without Al was flat, whereas that of the alloy with 2% or 5%Al was rough. The ΔK_(th), values of the alloys with 0%, 2% and 5%Al were 16, 17.5, and 20.5 MPam^(1/2), respectively.

Landau-level mixing, floating-up extended states, and scaling behavior in a GaAs-based two-dimensional electron system containing self-assembled InAs dots

Liu, Chieh-Wen,Liu, Chieh-I,Liang, C-T,Kim, Gil-Ho,Huang, C F,Hang, D R,Chang, Y H,Ritchie, D A Institute of Physics 2017 Semiconductor science and technology Vol.32 No.8

<P>Temperature-driven flow lines are studied in the conductivity plane in a GaAs-based two-dimensional electron system containing self-assembled InAs dots when Landau level filling factor <I>ν</I> = 2-4. In the insulator-quantum Hall (I-QH) transition resulting from the floating-up of the extended states, the flow diagram shows the critical behavior and we observed the expected semicircle in the strongest disorder case. By decreasing the effective disorder, we find that such flow lines can leave the I-QH regime and correspond to the plateau–plateau transition between <I>ν</I> = 4 and 2. The evolution of the conductivity curve at low magnetic fields demonstrates the importance of Landau-level mixing to the semicircle when the extended states float up.</P>

C. difficile 톡신이 야기하는 대장상피세포 미세소관 변형에 대한 초산의 억제 효능

윤이나(I Na Yoon ),김호(Ho Kim) 한국생명과학회 2018 생명과학회지 Vol.28 No.8

급성위막성대장염(Pseudomembranous colitis)은 C. difficile 세균이 분비하는 톡신A에 의해 유발되는 것으로 알려져 있다. 톡신A에 의한 점막 상피세포의 장벽기능 감소가 발병 원인으로 알려져 있다. 최근 연구에 의하면 톡신 A는 대장상피세포 속 HDAC-6의 활성을 높여 튜블린의 탈아세틸화를 증가시키는 것으로 알려져 있다. 튜블린 단백질의 탈아세틸화는 미세소관 불 형성을 초래하여 점막 상피세포의 극단적인 세포 형태 변형을 야기하게 되며 결국 상피세포의 고유기능인 장벽 기능이 파괴된다고 알려져 있다. 최근 연구자 등은 potassium acetate가 톡신A에 의한 튜블린 탈아세틸화와 미세소관 불 형성을 회복시켜 장염을 유의하게 억제함을 보고하였다. 따라서 본 연구에서는 아세틸기를 포함하는 또 다른 간단한 화학구조의 초산을 적용하여 톡신A의 세포독성을 억제하는지 확인해보고자 하였다. 인간 대장상피세포에서 초산 자극은 튜블린 단백질의 아세틸화를 유의하게 증가시켰다. 또한 초산은 대장상피세포 속 미세소관 형성과정도 강하게 촉진시킴을 확인하였다. 초산은 톡신A에 의한 튜블린 탈아세틸화와 미세소관 불 형성 그리고 세포독성 모두를 유의하게 회복시켰다. 이상의 결과는 초산에 의한 미세소관 형성 촉진이 톡신A에 의해 초래되는 세포골격계 파괴와 그로 인한 세포독성을 억제할 수 있음을 보여준다. 따라서 초산이 톡신A의 작용을 차단하여 위막성대장염 증상을 완화시킬 수 있는 치료제로서 개발 가치가 있음을 보여준다. Clostridium difficile (C. difficile) toxin A is known to cause acute gut inflammation in humans and animals by triggering cytoskeletal disorganization in gut epithelial cells. In human colonocytes, toxin A blocks microtubule assembly by directly increasing the enzymatic activity of histone deacetylase-6 (HDAC-6), a tubulin-specific deacetylase, thereby markedly decreasing tubulin acetylation, which is essential for microtubule assembly. Microtubule assembly dysfunction-associated alterations (i.e., toxin A-exposed gut epithelial cells) are believed to trigger barrier dysfunction and gut inflammation downstream. We recently showed that potassium acetate blocked toxin A-induced microtubule disassembly by inhibiting HDAC-6. Herein, we tested whether acetic acid (AA), another small acetyl residue-containing agent, could block toxin A-induced tubulin deacetylation and subsequent microtubule assembly. Our results revealed that AA treatment increased tubulin acetylation and enhanced microtubule assembly in an HT29 human colonocyte cell line. AA also clearly increased tubulin acetylation in murine colonic explants. Interestingly, the AA treatment also alleviated toxin A-induced tubulin deacetylation and microtubule disassembly, and MTT assays revealed that AA reduced toxin A-induced cell toxicity. Collectively, these results suggest that AA can block the ability of toxin A to cause microtubule disassembly-triggered cytoskeletal disorganization by blocking toxin A-mediated deacetylation of tubulin.

각종 버섯류로부터 안지오텐신 전환효소 저해제의 탐색

이대형 ( I Daehyeong ),김재호 ( Kim Jae Ho ),정종천 ( Jeong Jong Cheon ),공원식 ( Gong Won Sig ),유영복 ( Yu Yeong Bog ),박정식 ( Bak Jeong Sig ),유창현 ( Yu Changhyeon ),이종수 ( Lee Jongsu ) 한국균학회 2003 韓國菌學會誌 Vol.31 No.3

Effects of polysaccharide fractions from phellodendron chinese SCHNEID on tumor progression and immunopontentiation

Jun, Kya-I,Lee, Tae-Kyun,Kim, Cheorl-Ho Kyung Hee Oriental Medicine Research Center 2000 International journal of oriental medicine Vol.1 No.1

In the previous paper (Kim et al., Glycoconjugate Journal 16, 247-252, 1999), heteropolysaccharides from Korean medicinal plant, Phellodendri cortex (Hwangbek) showed a poten B-Iymphocyte-stimulating activity in a system using polyclonal antibody forming cells in C57BL/6XC3H mice at dosages of 2-10 mg. In a series of biolgical active polysaccharides from natural medicinal plants, the polysaccharide fractions were isolated and purified from Phellodendron chinese SCHNEID, and antitumor activities were examined at dosages of 2, 5 and 10 mg/100 g. F-7 and F-8 showed the highest tumor inhibitory activities (inhibition ratio 96.4 and 98.2% in 2 mg/100 g), and in dose of 5 mg/100 g, the inhibitory ratios were 95.3 and 97.5%, respectively. Furthermore, 10 mg/100 g of intraperitoneal (i.p.) injection gave 97.3 and 98.7% of inhibition. In oral administration, the inhibitory activities were not markedly observed, indicating that the polysaccharides are directly acting to immune system. When the effects on TS and TK activities were determined, TS activities in the F-2 and F-7-treated mice were markedly suppressed to 73.7% and 79.5% of that in the control (p<0.01), while there was little difference in TK activity with a slight decrease in F-2 only. However, in i.p. injection, TS activities in the F-2, F-5, F-7 and F-8-treated mice were markedly suppressed to 83% to 85% of that in the control (p<0.01). Furthermore, there was also significant differences in TK activities in F-2, F-5, F-7 and F-8-treated mice (p<0.05). Therefore, polysaccharide fraction F-8 was further purified to active fractions of F-9 and F-11 by gel permeation chromatography using TSK Gel HW50S. The purified polysaccharides of F-9 and F-11 were composed of GlcNAc (47.3%), Gal (24.7%) and Man (28.0%). These results clearly indicated that the i.p. injection is much effective to suppress tumor growth than oral administration.

Decay angular distributions of ^K* and ^D* vector mesons in pion-nucleon scattering

Kim, Sang-Ho,Oh, Yongseok,Titov, Alexander I. American Physical Society 2017 Physical Review C Vol.95 No.5

<P>The production mechanisms of open strangeness (K*) and open charm (D*) vector mesons in pi(-) p scattering, namely, pi(-) + p -> K*(0) + Lambda and pi(-) + p -> D*(-) + Lambda(+)(c) , are investigated within the modified quark-gluonstring model. To identify the major reaction mechanisms, we consider the subsequent decays of the produced vector mesons into two pseudoscalar mesons, i.e., K* -> K + pi and D* -> D + pi. We found that the decay distributions and density matrix elements are sensitive to the production mechanisms and can be used to disentangle the vector trajectory and pseudoscalar trajectory exchange models. Our results for K* production are compared with the currently available experimental data and the predictions for D* production process are presented as well. Our predictions can be tested at the present or planned experimental facilities.</P>

Modeling Three-Dimensional Groundwater Flows by the Body-Fitted Coordinate (BFC) Method: I. Stationary Biundary Problems

LEAP, DARRELL I,KOO, MIN HO 公州大學校 基礎科學硏究所 1998 自然科學硏究 Vol.7 No.-

Based on the body-fitted coordinate (BFC) method, a three-dimensional finite difference computer'code, BFC3DGW, was developed to simulate groundwater flow problems. Methodology and solution procedures of the BFC method for simulating groundwater flows, particularly when the flow domain is stationary as in the case of confined aquifers, arc described. The code was verified by comparing numerical results with analytical solutions for well-flow problems in an isosceles right-triangular aquifer. An example simulation is made to demonstrate capability of the code for solving flow problems in anisotropic aquifers where directions of anisotropy change continuously. The method differs from the conventional finite difference method (FDM) in the ability to use a flexible, nonorthogonal, and body-fitted grid. The main advantages of the method are the convenience of grid generation, the simplified implementation of boundary conditions, and the capability to construct a generalized computer code which can be consistently applied to problem domains of any shape.

Insertion of Alkali Metals into Open Framework, TaPS₆ by Using Alkali Metal Halide Fluxes: Single Crystal Structures of K_0.18TaPS₆, K_0.28TaPS₆, and Rb_0.09TaPS₆

Do, Jung-Hwan,Dong, Yong-Kwan,Kim, Jung-Wook,Hahn, Song-I,Yun, Ho-Seop Korean Chemical Society 2005 Bulletin of the Korean Chemical Society Vol.26 No.8

Three new quaternary tantalum thiophosphates, $K_{0.18}TaPS_6,\;K_{0.28}TaPS_6,\;and\;Rb_{0.09}TaPS_6$ have been synthesized by using reactive alkali metal halide fluxes and structurally characterized by single crystal X-ray diffraction techniques. The crystal structures of $K_{0.18}TaPS_6,\;K_{0.28}TaPS_6,\;and\;Rb_{0.09}TaPS_6$ contain 3-dimensional open framework anions, $[TaPS_6]^{x-}$(x = 0.09, 0.18, 0.28) with the empty channel which disordered alkali metal cations, $K^+\;and\;Rb^+$ are located in. Crystal data: $K_{0.18}TaPS_6$, tetragonal, space group$I4_1$/acd (no. 142), a=15.874(3) $\AA$, c=13.146(4) $\AA$, V=3312.7(12) ${\AA}^3$, K, Z=16, R1=0.0545. Crystal data: $K_{0.28}TaPS_6$, tetragonal, space group $I4_1$/acd (no. 142), a=15.880(2) $\AA$, c=13.134(3) $\AA$, V=3312.1(10) ${\AA}^3$, Z=16, R1=0.0562. Crystal data: $Rb_{0.09}TaPS_6$, tetragonal, space group I41/acd (no. 142), a=15.893(3) $\AA$, c=13.163(4) $\AA$, V=3324.7(15) ${\AA}^3$, Z=16, R1=0.0432.

비알코올성 지방간의 중증도에 따른 혈중 Ghrelin 농도 변화

유태우 ( Tae Woo Yoo ),조용균 ( Yong Kyun Cho ),강문수 ( Mun Su Kang ),오세용 ( Se Yong Oh ),박정호 ( Jung Ho Park ),김홍주 ( Hong Joo Kim ),박동일 ( Dong Il Park ),손정일 ( Chong Il Sohn ),전우규 ( Woo Kyu Jeon ),김병익 ( Byung I 대한내과학회 2006 대한내과학회지 Vol.71 No.1

목적: ghrelin은 주로 위에서 분비되는 새로운 peptide로서 음식물 섭취 및 식욕을 증가시키고 최근 인슐린 저항성 및 대사 증후군과의 관련성에 대해 많은 연구 결과가 보고되고 있다. 비알코올성 지방간은 인슐린 저항성 및 대사 증후군이 그 원인으로 잘 알려져 있는바 저자들은 비알코올성 지방간의 중증도에 따른 혈중 ghrelin 농도의 변화를 관찰하여 그들의 관련성에 대해 알아 보고자 하였다. 방법: 정상 성인 남성 65명(나이: 54.3±6.3세, 범위 42~70세)을 대상으로 하여 간 초음파 및 공복 혈중 ghrelin 농도를 측정하였다. 간 초음파 소견상 지방간의 유무 및 중증도에 따라 대상자를 세 군(Group I: 정상 27명, Group II: 경증: 24명, Group III: 중등도 이상의 지방간: 14명)으로 분류하였고, 세 군 간의 혈중 ghrelin 농도의 차이를 ANOVA test로 검정하였다. 또한 인슐린 저항성 지표인 HOMA 및 체질량 지수, 허리 둘레, 엉덩이 둘레, 허리-엉덩이 둘레비 등 인슐린 저항성 관련 인자와 혈중 ghrelin 농도와의 독립적인 상관성을 다중 회귀 분석으로 검정하였다. 결과: 간 초음파 소견상 지방간의 정도가 심해짐에 따라 혈중 ghrelin 농도가 낮아지는 경향을 보였으나 (Group I: 정상 230.9±94.3, Group II: 경증 195.2±97.2, Group III: 중등도 이상 지방간 164.3±71.4 pmol/L) 통계적으로 의미있는 결과를 얻지는 못하였으며(p=0.081), 인슐린 저항성 지표인 HOMA 및 체질량 지수, 허리 둘레, 엉덩이 둘레, 허리-엉덩이 둘레비 등 인슐린 저항성 관련 인자는 혈중 ghrelin 농도와 독립적인 관련성을 관찰할 수 없었다. 결론: 본 연구의 결과로 인슐린 저항성과 혈중 ghrelin 농도의 관련성을 증명하지는 못하였다. 하지만 간 초음파 소견상 지방간의 중증도가 심해질수록 혈중 ghrelin 농도가 낮아지는 경향을 관찰할 수 있었다. 따라서 향후 추가적인 연구로 이들의 관련성에 대한 증명이 필요할 것으로 생각한다. Background: Recently, ghrelin has been reported to be associated with insulin resistance. Nonalcoholic fatty liver disease (NAFLD) is a condition in which insulin resistance relatively plays a pivotal role. The aim of this study was to evaluate the change of serum ghrelin concentration according to severity of hepatosteatosis. Methods: Sixty five apparently normal male adults who underwent health screen examinations were classified into three groups, Group I: normal (27 subjects), Group II: mild (24 subjects) and Group III: moderate to severe fatty liver (14 subjects), according to ultrasonographic findings of liver. We analyzed the association between serum ghrelin concentration and severity of hepatosteatosis by ANOVA test. And the independent correlation between serum ghrelin concentration and insulin resistance related factors, HOMA (homeostatic model assessment), BMI (body mass index), WC (waist circumference), HC (hip circumference), WHR (waist to hip circumference ratio) were analyzed by multiple linear regression analysis. Results: Serum ghrelin concentration tended to decrease according to severity of hepatosteatosis (Group I: 230.9±94.3, Group II: 195.2±97.2, Group III: 164.3±71.4 pmol/L). But this was statistically insignificant (p=0.081). The independent correlation between serum ghrelin concentration and insulin resistance related factors were not observed. Conclusions: Our study did not prove the correlation between insulin resistance related factors and serum ghrelin concentration in NAFLD according to severity of hepatosteatosis. However, we found a tendency to decrease serum ghrelin concentration according to severity of hepatosteatosis. So, further studies are required for certification these correlations.(Korean J Med 71:45-51, 2006)

A study on the diatomaceous earth filtr’ation of recycling basin supernatant in the water treatment plant

Dae-Yewn Shin,Young-Ho Chol,Ok-Ran Moon,Hymg-I1 Choi,Kyung- Hoon Chung,Chin-Surk ko 한국환경보건학회 2003 한국환경보건학회 학술대회 자료집 Vol.2003 No.-