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831.
Hwangseo Park 《Journal of computational chemistry》2010,31(5):897-903
Backbone–backbone hydrogen bonds (BBHBs) are one of the most abundant interactions at the interface of protein–protein complex. Here, we propose an angle‐dependent potential energy function for BBHB based on density functional theory (DFT) calculations and the operation of a genetic algorithm to find the optimal parameters in the potential energy function. The angular part of the energy funtion is assumed to be the product of the power series of sine and cosine functions with respect to the two angles associated with BBHB. Two radial functions are taken into account in this study: Morse and Leonard‐Jones 12‐10 potential functions. Of these two functions under consideration, the former is found to be more accurate than the latter in terms of predicting the binding energies obtained from DFT calculations. The new HB potential function also compares well with the knowledge‐based potential derived by applying Boltzmann statistics for a variety of protein–protein complexes in protein data bank. © 2009 Wiley Periodicals, Inc. J Comput Chem, 2010 相似文献
832.
Hwan-Seo Park In-Tae Kim Yong-Jun Cho Mi-Sook Son Hee-Chul Eun 《Journal of Radioanalytical and Nuclear Chemistry》2010,283(2):267-272
Radioactive molten salt generated from a pyrochemical process to separate reusable U and TRU elements is one of problematic
wastes to manage for a final disposal. For the minimization of final waste, it is desirable to selectively remove radionuclides
from the waste salts. In this paper, structural change of some zeolites in a series of molten salt systems and its removal
behavior of CsCl was investigated. Zeolite-4A(LTA) was transformed into LiAlSiO4 and Li-sodalite with the mol-fraction of LiCl in LiCl–KCl system at 650 °C while it was not changed in NaCl–KCl at 750 °C,
regardless of mol-fraction of metal chloride. Other commercial zeolite with specific structure (FAU) had the same trends on
the structural stability in molten salt system. From the Cs removal experiments, the decomposed zeolitic materials in molten
salt lost their removal ability of Cs. In conclusion, a new selective material or method should be investigated or developed
for obtaining the validity on the separation of group I and II radionuclides from a molten waste salt because the zeolite
4A is unstable in the LiCl system and it also showed a low capacity in the LiCl–KCl phase. This paper gives basic information
on the removal of radionuclides from molten systems by using zeolitic materials. 相似文献
833.
Chang Yeon Lee Dr. Jae Kwon Jang Chul Hoon Kim Dr. Jaehoon Jung Bo Keun Park Dr. Jihee Park Wonyong Choi Prof. Young‐Kyu Han Dr. Taiha Joo Prof. Joon T. Park Prof. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2010,16(19):5586-5599
A new artificial photosynthetic triad array, a [60]fullerene–triosmium cluster/zinc–porphyrin/boron–dipyrrin complex ( 1 , Os3C60/ZnP/Bodipy), has been prepared by decarbonylation of Os3(CO)8(CN(CH2)3Si(OEt)3)(μ3‐η2:η2:η2‐C60) ( 6 ) with Me3NO/MeCN and subsequent reaction with the isocyanide ligand CNZnP/Bodipy ( 5 ) containing zinc porphyrin (ZnP) and boron dipyrrin (Bodipy) moieties. Triad 1 has been characterized by various spectroscopic methods (MS, NMR, IR, UV/Vis, photoluminescence, and transient absorption spectroscopy). The electrochemical properties of 1 in chlorobenzene (CB) have been examined by cyclic voltammetry; the general feature of the cyclic voltammogram of 1 is nine reversible one‐electron redox couples, that is, the sum of those of 5 and 6 . DFT has been applied to study the molecular and electronic structures of 1 . On the basis of fluorescence‐lifetime measurements and transient absorption spectroscopic data, 1 undergoes an efficient energy transfer from Bodipy to ZnP and a fast electron transfer from ZnP to C60; the detailed kinetics involved in both events have been elucidated. The SAM of triad 1 ( 1 /ITO; ITO=indium–tin oxide) has been prepared by immersion of an ITO electrode in a CB solution of 1 and diazabicyclo‐octane (2:1 equiv), and characterized by UV/Vis absorption spectroscopy, water contact angle, X‐ray photoelectron spectroscopy, and cyclic voltammetry. The photoelectrochemical properties of 1 /ITO have been investigated by a standard three‐electrode system in the presence of an ascorbic acid sacrificial electron donor. The quantum yield of the photoelectrochemical cell has been estimated to be 29 % based on the number of photons absorbed by the chromophores. Our triad 1 is unique when compared to previously reported photoinduced electron‐transfer arrays, in that C60 is linked by π bonding with little perturbation of the C60 electron delocalization. 相似文献
834.
Jookeun Park Gun Woong Bahng JongOh Choi Jongseon Park 《Accreditation and quality assurance》2010,15(8):445-450
Technical barrier to trade (TBT) has become one of the significant non-tariff measures with the advent of the WTO system in
1995. The key issue in TBT is that technical regulations, standards, and conformity assessment should not be used as barriers
to trade. Regarding conformity assessment, the WTO/TBT Agreement recommends members to enter into negotiations for the mutual
recognition of results of each other’s conformity assessment, as well as to permit participation of conformity assessment
bodies located in other members. In this paper, it will be reviewed why the role of measurement science is important in terms
of international effort to eliminate technical barriers to trade particularly in the area of conformity assessment. 相似文献
835.
Intermittent synchronization in a network of bursting neurons 总被引:1,自引:0,他引:1
Synchronized oscillations in networks of inhibitory and excitatory coupled bursting neurons are common in a variety of neural systems from central pattern generators to human brain circuits. One example of the latter is the subcortical network of the basal ganglia, formed by excitatory and inhibitory bursters of the subthalamic nucleus and globus pallidus, involved in motor control and affected in Parkinson's disease. Recent experiments have demonstrated the intermittent nature of the phase-locking of neural activity in this network. Here, we explore one potential mechanism to explain the intermittent phase-locking in a network. We simplify the network to obtain a model of two inhibitory coupled elements and explore its dynamics. We used geometric analysis and singular perturbation methods for dynamical systems to reduce the full model to a simpler set of equations. Mathematical analysis was completed using three slow variables with two different time scales. Intermittently, synchronous oscillations are generated by overlapped spiking which crucially depends on the geometry of the slow phase plane and the interplay between slow variables as well as the strength of synapses. Two slow variables are responsible for the generation of activity patterns with overlapped spiking, and the other slower variable enhances the robustness of an irregular and intermittent activity pattern. While the analyzed network and the explored mechanism of intermittent synchrony appear to be quite generic, the results of this analysis can be used to trace particular values of biophysical parameters (synaptic strength and parameters of calcium dynamics), which are known to be impacted in Parkinson's disease. 相似文献
836.
Culver RL Park JD Leighton TG Coles DG 《The Journal of the Acoustical Society of America》2011,130(6):3812-3826
The coherent processing of signals from multiple hydrophones in an array offers improvements in angular resolution and signal-to-noise ratio. When the array is steered in a particular direction, the signals arriving from that direction are added in phase, and any signals arriving from other directions are not. Array gain (AG) is a measure of how much the signal arriving from the steering direction is amplified relative to signals arriving from all other directions. The subject of this paper is the manner in which the AG of an acoustic array operating in water that contains air bubbles is affected by scattering from nearby bubbles. The effects of bubbles on acoustic attenuation and dispersion are considered separately from their effects on AG. Acoustic measurements made in bubbly water using the AB Wood tank at the Institute of Sound and Vibration Research, University of Southampton, in June 2008 show that as bubble density increases, relative phase shifts in individual hydrophone signals increase and signal correlation among the hydrophones is reduced. A theory and numerical simulation linking bubble density at the hydrophone to the AG is in good agreement with the measurements up to the point where multiple scattering becomes important. 相似文献
837.
Lenka Dubcova Pavel Solin Glen Hansen HyeongKae Park 《Journal of computational physics》2011,230(4):1182-1197
Multiphysics solution challenges are legion within the field of nuclear reactor design and analysis. One major issue concerns the coupling between heat and neutron flow (neutronics) within the reactor assembly. These phenomena are usually very tightly interdependent, as large amounts of heat are quickly produced with an increase in fission events within the fuel, which raises the temperature that affects the neutron cross section of the fuel. Furthermore, there typically is a large diversity of time and spatial scales between mathematical models of heat and neutronics. Indeed, the different spatial resolution requirements often lead to the use of very different meshes for the two phenomena. As the equations are coupled, one must take care in exchanging solution data between them, or significant error can be introduced into the coupled problem. We propose a novel approach to the discretization of the coupled problem on different meshes based on an adaptive multimesh higher-order finite element method (hp-FEM), and compare it to popular interpolation and projection methods. We show that the multimesh hp-FEM method is significantly more accurate than the interpolation and projection approaches considered in this study. 相似文献
838.
The authors introduce frequency selective beam splitters for surface plasmon polaritons (SPPs) in a metal-insulator-metal (MIM) structure. In the splitters, a part of SPPs keeps propagating straight along the initial direction, while the other part is split into the arm attached at right angle. The splitting ratio can be controlled by varying the width and the electric permittivity of the dielectric layer in the MIM, and by varying the width of the attached arm. 相似文献
839.
A double lambda four-level system could be implemented with biexcitonic transitions on GaAs quantum well. We observed that the phase dependent biexcitonic transition could be explained by interference between one-photon and three-photon transition in a double lambda four-level system. An ultralow-light switch pulse could control 80% of biexcitonic absorption, which demonstrated all-optical switching with biexcitonic double lambda system. 相似文献
840.
Vossen A Seidl R Adachi I Aihara H Aushev T Balagura V Bartel W Bischofberger M Bondar A Bračko M Browder TE Chang MC Chen A Chen P Cheon BG Cho K Choi Y Eidelman S Feindt M Gaur V Gabyshev N Garmash A Golob B Perdekamp MG Haba J Hayasaka K Horii Y Hoshi Y Hou WS Hyun HJ Inami K Ishikawa A Iwabuchi M Iwasaki Y Iwashita T Joshi NJ Kichimi H Kim HO Kim MJ Ko BR Kumita T Lange JS Lee MJ Lee SH Leitgab M Li Y Liu C Liventsev D Louvot R McOnie S Miyata H Miyazaki Y Mizuk R Mohanty GB Nakano E 《Physical review letters》2011,107(7):072004
The interference fragmentation function translates the fragmentation of a quark with a transverse projection of the spin into an azimuthal asymmetry of two final-state hadrons. In e(+)e(-) annihilation the product of two interference fragmentation functions is measured. We report nonzero asymmetries for pairs of charge-ordered π(+)π(-) pairs, which indicate a significant interference fragmentation function in this channel. The results are obtained from a 672 fb(-1) data sample that contains 711 × 10(6) π(+)π(-) pairs and was collected at and near the Υ(4S) resonance, with the Belle detector at the KEKB asymmetric-energy e(+)e(-) collider. 相似文献