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21.
Monitoring the aggregation processes of amyloid-β using a spin-labeled, fluorescent nitroxyl radical
Mito F Yamasaki T Ito Y Yamato M Mino H Sadasue H Shirahama C Sakai K Utsumi H Yamada K 《Chemical communications (Cambridge, England)》2011,47(17):5070-5072
Amyloid nitroxyl radical (nitroxide) ligands were used to detect amyloid-β fibrils, the main constituents of senile plaques in Alzheimer's disease, using anisotropic ESR spectra, and were found to affect the aggregation process due to the radical functionality. These compounds have great potential as novel and multifunctional probes, combining spin labels, spin probes, and fluorescence probes. 相似文献
22.
Control of very low oxygen partial pressures was performed in the range of 10−21-10−24 Pa at 750°C by pumping oxygen into the purified hydrogen stream with a stabilized zirconia cell. The oxygen partial pressures were monitored by a stabilized zirconia sensor. The stabilized zirconia oxygen sensor was calibrated by H2-CO2 gas buffer mixture in the range of oxygen pressure from 10−17 to 10−21 Pa, and oxygen partial pressures below 10−21 Pa were measured by extrapolating the calibration line to very low oxygen partial pressures. The lowest oxygen partial pressure controlled was 10−24 Pa at 750°C, which was limited by gas leaks in the system and also by the reduction of the ionic transference number in solid electrolyte used as the oxygen pump. 相似文献
23.
T. Takagahara 《Solid State Communications》1983,47(5):345-347
Recently Kuwata and Nagasawa observed the correlation between the upper and lower branch polaritons in the experiments of two-photon polarization rotation via the excitonic molecule level in CuCl crystals. An interpretation will be presented that the correlation is not intrinsic but is caused by the change of state of the sample due to the four polariton parametric scattering under a rather strong excitation. This interpretation can explain the decrease of the signal of two-photon polarization rotation and the reflectivity if an appropriate amount of the population change is assumed to occur under the two-photon resonance of excitonic molecules. 相似文献
24.
Konstantin?Kogan Eugene?KhmelnitskyEmail author Toshihide?Ibaraki 《Journal of Global Optimization》2005,31(1):17-43
The assignment problem is a well-known operations research model. Its various extensions have been applied to the design of distributed computer systems, job assignment in telecommunication networks, and solving diverse location, truck routing and job shop scheduling problems.This paper focuses on a dynamic generalization of the assignment problem where each task consists of a number of units to be performed by an agent or by a limited number of agents at a time. Demands for the task units are stochastic. Costs are incurred when an agent performs a task or a group of tasks and when there is a surplus or shortage of the task units with respect to their demands. We prove that this stochastic, continuous-time generalized assignment problem is strongly NP-hard, and reduce it to a number of classical, deterministic assignment problems stated at discrete time points. On this basis, a pseudo-polynomial time combinatorial algorithm is derived to approximate the solution, which converges to the global optimum as the distance between the consecutive time points decreases. Lower bound and complexity estimates for solving the problem and its special cases are found. 相似文献
25.
Our aim in this note is to deal with boundary limits of monotone Sobolev functions with ▽u∈ Lp(·)logLq(·)(B) for the unit ball BRn. Here p(·) and q(·) are variable exponents satisfyingthe log-Hlder and the log log-Hlder conditions, respectively. 相似文献
26.
T. Takagahara 《Phase Transitions》2013,86(1):281-363
In this article, the fundamental physics of multi-exciton states in semiconductor nano-crystals is reviewed focusing on the mesoscopic enhancement of the excitonic radiative decay rate and the excitonic optical nonlinearity and the mechanism of their saturation with increase of the nanocrystal size. In the case of the radiative decay rate the thermal excitation of excited exciton states having small oscillator strength within the homogeneous linewidth of the exciton ground state is essential in determining the saturation behavior. The weakly correlated exciton pair states are found to cause a cancellation effect in the third-order nonlinear optical susceptibility at the exciton resonance, providing the first consistent understanding of the experimentally observed saturation of the mesoscopic enhancement of the excitonic optical nonlinearity. The presence of the weakly correlated exciton pair states is confirmed convincingly from the good correspondence between theory and experiments on the induced absorption spectra from the exciton state in CuCl nanocrystals. Furthermore, ultrafast relaxation processes of biexcitons are discussed in conjunction with the observed very fast rise of the biexciton gain in nanocrystals. In prospect of future progress in research, the theoretical formulation to calculate the triexciton states as one of the multi-exciton states beyond the biexciton is presented for the first time including the electron-hole exchange interaction. 相似文献
27.
Masami Kumagai Akihito Taguchi Toshihide Takagahara Takahisa Ohno Kousuke Yakubo 《Solid State Communications》2008,145(3):154-158
The exciton properties of thin nanotube structures are investigated theoretically. Anisotropic size dependencies have been found in the exciton binding energy, the kinetic energy for the relative motions of an electron and a hole, and the wavefunction. These anisotropies arise from the different boundary conditions in the tube-length and circumferential directions, namely, the topological features of nanotubes. We also found that it is possible to change the topology of exciton wavefunctions by varying the tube-length and the tube-radius. These findings suggest that the optical properties of nanotubes such as oscillator strength or nonlinear susceptibilities can be controlled by tuning the structural parameters, thus yielding a novel guiding principle for designing optical functional materials. 相似文献
28.
Direct Estimation of the Surface Location of Immobilized Functional Groups for Concerted Catalysis Using a Probe Molecule 下载免费PDF全文
Hiroto Noda Dr. Ken Motokura Prof. Dr. Yusuke Wakabayashi Kaori Sasaki Dr. Hiroo Tajiri Dr. Akimitsu Miyaji Dr. Sho Yamaguchi Prof. Dr. Toshihide Baba 《Chemistry (Weinheim an der Bergstrasse, Germany)》2016,22(15):5113-5117
The location of active sites during concerted catalysis by a metal complex and tertiary amine on a SiO2 surface is discussed based on the interaction between the functionalized SiO2 surface and a probe molecule, p‐formyl phenylboronic acid. The interactions of the probe molecule with the surface functionalities, diamine ligand, and tertiary amine, were analyzed by FT‐IR and solid‐state 13C and 11B MAS NMR. For the catalyst exhibiting high 1,4‐addition activity, the diamine ligand and tertiary amine base exist in closer proximity than in the catalyst with low activity. 相似文献
29.
Demizu Y Kubo Y Miyoshi H Maki T Matsumura Y Moriyama N Onomura O 《Organic letters》2008,10(21):5075-5077
The first catalytic process for protection of hydroxyl groups in sugars has been developed. Highly regioselective protection was accomplished along with high chemical yield. The regioselectivity of the benzoylation was realized as an intrinsic character of sugars based on a stereorelationship among their hydroxyl groups. Furthermore, complete protection of alpha-methyl glucoside and beta-methyl xyloside was accomplished. 相似文献
30.
Ohyama K Oyamada K Kishikawa N Ohba Y Wada M Maki T Nakashima K Kuroda N 《Journal of chromatography. A》2008,1208(1-2):242-245
Three new chiral stationary phases with different lengths of l-phenylalanine peptide were prepared by solid-phase synthesis with tert-butoxycarbonyl (Boc)-l-phenylalanine on silica. The effect of phenylalanine peptide length on enantioselectivity was studied. The best separation of R/S-warfarin was achieved by the chiral stationary phase with intermediate peptide length. These stationary phases were found to exist mainly in alpha-helical conformation by using FT-IR spectra. The end-capping reagents for the N-terminus of the peptide were also evaluated. 相似文献