Protein dynamics viewed by hydrogen exchange.

Skinner, John J,Lim, Woon K,B?dard, Sabrina,Black, Ben E,Englander, S Walter Cambridge University Press 2012 Protein science Vol.21 No.7

<P>To examine the relationship between protein structural dynamics and measurable hydrogen exchange (HX) data, the detailed exchange behavior of most of the backbone amide hydrogens of Staphylococcal nuclease was compared with that of their neighbors, with their structural environment, and with other information. Results show that H-bonded hydrogens are protected from exchange, with HX rate effectively zero, even when they are directly adjacent to solvent. The transition to exchange competence requires a dynamic structural excursion that removes H-bond protection and allows exposure to solvent HX catalyst. The detailed data often make clear the nature of the dynamic excursion required. These range from whole molecule unfolding, through smaller cooperative unfolding reactions of secondary structural elements, and down to local fluctuations that involve as little as a single peptide group or side chain or water molecule. The particular motion that dominates the exchange of any hydrogen is the one that allows the fastest HX rate. The motion and the rate it produces are determined by surrounding structure and not by nearness to solvent or the strength of the protecting H-bond itself or its acceptor type (main chain, side chain, structurally bound water). Many of these motions occur over time scales that are appropriate for biochemical function.</P>

Divertor Stabilization Experiments in the Hanbit Mirror Device

England, A. C.,Lee, D. K.,Lee, S. G.,Kwon, M.,Yoon, S. W.,Yasaka, Y. Informa UK (TaylorFrancis) 2007 Fusion science and technology Vol.51 No.2

Mirror stabilization experiments in the Hanbit device

England, A.C.,Lee, D.K.,Lee, S.G.,Kwon, M.,Yoon, S.W.,Yasaka, Y.,Sugimoto, N.,Katanuma, I.,Yashiro, K.,Imai, T. International Atomic Energy Agency 2009 Nuclear fusion Vol.49 No.12

<P>The Hanbit magnetic mirror device has been involved in a series of experiments on stabilization of the MHD flute type mode. We undertook investigations to see whether a divertor and the kinetic stabilizer (KS) of Post <I>et al</I> can stabilize the MHD instability. The Hanbit divertor configuration used one of the central cell coils with reversed current as the divertor coil and two other coils with increased current to compensate the field droop. The divertor eliminated the <I>m</I> = −1 instability when the null point was inside the vacuum tank. The KS used microwave produced plasmas on field lines in the cusp tank region. Two coils on the cusp tank were configured to produce expanding field lines with a large positive radius of curvature. A 5 kW 2.45 GHz magnetron was used to produce an electron cyclotron resonance heated plasma pressure in this region. A reduction in instability duration was observed for high power plasmas. However, for low power plasmas that terminate violently with an <I>m</I> = −1 instability, the KS action made the duration of the instability longer.</P>

Preionization in the Hanbit Tandem Mirror

England, A. C.,Hong, J. S.,Kwon, M.,Park, M. K.,Choi, J. H.,Choi, J. W.,Lee, D. K.,Lee, T. G.,Bak, J. G. Informa UK (TaylorFrancis) 2005 Fusion science and technology Vol.47 No.1

Re-assessing the enhanced permeability and retention effect in peripheral arterial disease using radiolabeled long circulating nanoparticles

England, C.G.,Im, H.J.,Feng, L.,Chen, F.,Graves, S.A.,Hernandez, R.,Orbay, H.,Xu, C.,Cho, S.Y.,Nickles, R.J.,Liu, Z.,Lee, D.S.,Cai, W. IPC Science and Technology Press 2016 Biomaterials Vol.100 No.-

<P>As peripheral arterial disease (PAD) results in muscle ischemia and neovascularization, it has been claimed that nanoparticles can passively accumulate in ischemic tissues through the enhanced permeability and retention (EPR) effect. At this time, a quantitative evaluation of the passive targeting capabilities of nanoparticles has not been reported in PAD. Using a murine model of hindlimb ischemia, we quantitatively assessed the passive targeting capabilities of Cu-64-labeled PEGylated reduced graphene oxide iron oxide nanoparticles (Cu-64-RGO-IONP-PEG) through the EPR effect using positron emission tomography (PET) imaging. Serial laser Doppler imaging was performed to monitor changes in blood perfusion upon surgical induction of ischemia. Nanoparticle accumulation was assessed at 3, 10, and 17 days post-surgery and found to be highest at 3 days post-surgery, with the ischemic hindlimb displaying an accumulation of 14.7 +/- 0.5% injected dose per gram (%ID/g). Accumulation of Cu-64-RGO-IONP-PEG was lowest at 17 days post-surgery, with the ischemic hindlimb displaying only 5.1 +/- 0.5%ID/g. Furthermore, nanoparticle accumulation was confirmed by photoacoustic imaging (PA). The combination of PET and serial Doppler imaging showed that nanoparticle accumulation in the ischemic hindlimb negatively correlated with blood perfusion. Thus, we quantitatively confirmed that Cu-64-RGO-IONP-PEG passively accumulated in ischemic tissue via the EPR effect, which is reduced as the perfusion normalizes. As Cu-64-RGO-IONP-PEG displayed substantial accumulation in the ischemic tissue, this nanoparticle platform may function as a future theranostic agent, providing both imaging and therapeutic applications. (C) 2016 Elsevier Ltd. All rights reserved.</P>

Experiments in the Hanbit Mirror Device with the Kinetic Stabilizer

England, A. C.,Lee, D. K.,Lee, S. G.,Kwon, M.,Yoon, S. W. Informa UK (TaylorFrancis) 2007 Fusion science and technology Vol.51 No.2

First Results of the Kinetic Stabilizer in the Hanbit Tandem Mirror

A. C. England,B. H. Park,D. C. Seo,D. K. Lee,K. I. You,M. Kwon 한국물리학회 2006 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.49 No.III

R. F. Post [1.4] has proposed the Kinetic Stabilizer (KS) to be used to stabilize mirror machines against MHD interchange instabilities. Briefly, the concept is that by locating a stabilizing plasma pressure on the field lines at a critical region in an expanding field region with good field line curvature outside the mirrors, the plasma in the central cell (CC) in regions of unfavorable curvature can be stabilized. The original concept proposed low energy ion beams injected along field lines in the expanding field region. The injected ion beams would stagnate and reflect, thus producing a stabilizing pressure on the field lines. We applied the KS concept to the Hanbit tandem mirror [5] by using a 2.45 GHz microwave source. Such a source should be able to supply a stabilizing KS plasma by electron cyclotron resonant heating (ECRH) on the expanding field lines in the cusp section. We have calculated the coil currents for the present Hanbit coil system such that the KS concept is optimized for 2.45 GHz. The cusp plasma electron temperature, Te, rises about an order of magnitude when the ECRH is applied in the presence of stable CC plasmas. The cusp plasma electron density, ne, also rises. There is some variation of Te near the ECRH position as determined by probe and field scans. New drift-wave-like fluctuations appear in the CC plasma when the ECRH power is turned on. It appears that the ECRH-produced KS plasma produces turbulence in the CC plasma. To date, we have been unable to produce an m = .1 instability, and hence we have not been able to attempt flute stabilization.at

Personal Value Systems of Korean Managers

George W. England 고려대학교 아세아문제연구소 1968 亞細亞硏究 Vol.11 No.2

Bulletin 17C의 새로운 빈도해석 기법을 적용한 국내 다목적댐의 설계홍수량 재산정

손찬영,이태삼,John F. England,박무종 한국방재학회 2016 한국방재학회논문집 Vol.16 No.6

Flooding is one of the costliest natural disasters in terms of loss of human life and property. Accurate flood frequency and magnitude estimation is essential to prevent natural disasters. In the United States, a new version of Bulletin 17C, which is the practical guideline of flood frequency analysis, is prepared about to come out soon with significant methodological developments. It might be beneficial to the scientific community how much difference can be made with the current design flood in South Korea compared to the estimates through Bulletin 17C. Therefore, we applied the Bulletin 17C in estimating a flood quantiles of eight multi-purpose dams using the enhanced methods of MGBT and EMA for flood frequency analysis and compared to the flood quantiles estimated by the existing estimation. According to the results of flood quantiles, flood quantiles in most dams estimated by Bulletin 17C presented reasonable values except for those in Imha and Hapcheon dams when the sample size was large. The results indicate that flood frequency analysis proposed Bulletin 17C might be comparable to the existing estimate for rehabilitation of dams, disasters management, and estimation of design flood. 홍수범람은 경제적인 측면에서 인명 및 재산 피해의 형태로 막대한 피해규모 및 피해액을 야기시키는 자연재해 중 하나이다. 자연재해에 대한 대비 및 대응을 위해서는 정확한 홍수의 빈도와 규모산정은 필수적이다. 미국의 경우 새로운 홍수빈도해석기법을 포함한 Bulletin 17C를 준비 중에 있으며 곧 출간될 예정이다. 기존 국내에서 산정된 설계홍수량과 Bulletin 17C에서 제시한 방법을 통해 계산된 값에 대해서 정량적인 차이를 검토한다면 국내에서 산정된 댐의 설계홍수량 값들에 대한 고찰이 이루어질 것으로 판단된다. 따라서 본 연구에서는 국내 적용성 검토를 위해 치수적으로 중요한 역할을 하고 있는 8개 다목적 댐을 대상으로 Bulletin 17C에서 보완된 두 가지 기법(MGBT, EMA)을 적용하여 홍수빈도해석을 수행하였고 기존의 결과와 비교하였다. 분석결과, Bulletin 17C에 의해 산정한 홍수량의 경우 상대적으로 유입량 자료가 부족한 임하댐, 합천댐을 제외하고는 현실적인 확률홍수량 값이 도출됨을 확인하였다. Bulletin 17C에서 제안하는 홍수빈도해석은 댐 재개발, 자연재해관리, 설계홍수량산정 등에 활용가능할 것으로 판단된다.

Study on Pre-Ionization Using Second-Harmonic Electron Cyclotron Waves for the KSTAR First Plasma

Young Soon Bae,Alan England 한국물리학회 2007 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.51 No.II

Korea Superconducting Tokamak Advanced Research (KSTAR) is adopting electron cyclotron heating (ECH)-assisted startup for the flexibility and reliability of KSTAR operation through pre-ionization by using EC waves. An 84-GHz ECH system is being installed on the KSTAR tokamak, and the maximum available ECH power is presently 500 kW with a maximum duration of 2 s. A plasma breakdown voltage (or loop voltage) in the range of 4 V to 5 V is needed when fundamental harmonic EC power is used. Currently, second-harmonic ECH-assisted start-up is under consideration because a low toroidal field of $B_T$ $\sim$ 1.5 T is desirable for safety and because the high-beta experiments will be done in the initial operation phase. There have been limited studies of the efficacy of plasma breakdown by second-harmonic pre-ionization. The studies reported in this paper address the effectiveness of second-harmonic pre-ionization by 84-GHz EC-waves and alternatives to it for KSTAR. The optimum and threshold conditions for its successful start-up are calculated using a 0-dimentional time-dependent plasma-evolution code. The feasibility of second-harmonic breakdown of the KSTAR plasma is studied based on the recent experimental results in DIII-D tokamak on second-harmonic breakdown where 60 GHz and 110 GHz EC power was used. In this feasibility study, the ionization growth rate in G. L. Jackson's theoretical model, which was used for the comparison with International Thermonuclear Experimental Reactor (ITER) second-harmonic pre-ionization, is also compared with KSTAR second-harmonic pre-ionization based on the DIII-D experimental results.