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981.
Abstract Energy loss spectra of 1000 keV electrons transmitted by [111]-: riented thin silicon crystals were observed by an energy analyzer attached to the HVEM. The crystals were set to the systematic 220 Bragg reflection. Measurements were made for crystal thickness ranging from 1000 to 10,000 Å, which were determined by observations of pendellösung fringes. Results were analyzed with Landau's transport equation, giving the : onclusion that the loss probability, which is the reciprocal of the mean free path, is 0.52 ± 0.02 × 10?3 A?1 for plasmon excitation and 1.50 ± 0.02 × 10?3 A?1 for L-electron excitation. 相似文献
982.
Hiroshi Nagase 《代数通讯》2013,41(10):4561-4577
We count the number of isomorphism classes of hom-orthogonal partial tilting modules over path algebras of Dynkin quiver of type 𝔸 n , 𝔻 n , 𝔼 n . This number is independent on the choice of an orientation of the arrows, and the number for 𝔸 n or 𝔻 n -type can be expressed as a special value of a hypergeometric function. As a consequence of our theorem, we obtain a minimum value of the number of basic relative invariants of corresponding regular prehomogeneous vector spaces. 相似文献
983.
984.
This paper discusses an alternative criterion for estimating the baseband transfer function of multimode optical fibers. The optical fibers having little mode conversions show that the baseband frequency characteristics are affected strongly by the launching condition of an input optical pulse. In the criterion presented here, the baseband transfer function in such fibers is estimated by considering the launching condition that excites all fiber modes uniformly in amplitudes. In order to obtain such a transfer function, the actual responses affected by the launching conditions are measured together with the modal power distributions for different kinds of launching conditions. A numerical procedure is then presented that enables us to derive the baseband transfer function independently of modal power distributions. Experimental results at λ x= 633 nm and 856 nm are presented for step index fibers (0.1 and 0.2 km long) having a core radius of 30 pm (its refractive index is 1.452) and a refractive index difference of 0.7%. 相似文献
985.
A method for engineering the global behavior of populations of rhythmic elements is presented. The framework, which is based on phase models, allows a nonlinear time-delayed global feedback signal to be constructed which produces an interaction function corresponding to the desired behavior of the system. It is shown theoretically and confirmed in numerical simulations that a polynomial, delayed feedback is a versatile tool to tune synchronization patterns. Dynamical states consisting of one to four clusters were engineered to demonstrate the application of synchronization engineering in an experimental electrochemical system. 相似文献
986.
Development and testing of a CW-EPR apparatus for imaging of short-lifetime nitroxyl radicals in mouse head 总被引:1,自引:1,他引:0
Sato-Akaba H Fujii H Hirata H 《Journal of magnetic resonance (San Diego, Calif. : 1997)》2008,193(2):191-198
This article describes a method for reducing the acquisition time in three-dimensional (3D) continuous-wave electron paramagnetic resonance (CW-EPR) imaging. To visualize nitroxyl spin probes, which have a short lifetime in living organisms, the acquisition time for a data set of spectral projections should be shorter than the lifetime of the spin probes. To decrease the total time required for data acquisition, the duration of magnetic field scanning was reduced to 0.5 s. Moreover, the number of projections was decreased by using the concept of a uniform distribution. To demonstrate this faster data acquisition, two kinds of nitroxyl radicals with different decay rates were measured in mice. 3D EPR imaging of 4-hydroxy-2,2,6,6-tetramethylpiperidine-d17-1-15N-1-oxyl in mouse head was successfully carried out. 3D EPR imaging of nitroxyl spin probes with a half-life of a few minutes was achieved for the first time in live animals. 相似文献
987.
A loop resonator for slice-selective in vivo EPR imaging in rats 总被引:2,自引:1,他引:1
Hirata H He G Deng Y Salikhov I Petryakov S Zweier JL 《Journal of magnetic resonance (San Diego, Calif. : 1997)》2008,190(1):124-134
A loop resonator was developed for 300 MHz continuous-wave electron paramagnetic resonance (CW-EPR) spectroscopy and imaging in live rats. A single-turn loop (55 mm in diameter) was used to provide sufficient space for the rat body. Efficiency for generating a radiofrequency magnetic field of 38 microT/W(1/2) was achieved at the center of the loop. For the resonator itself, an unloaded quality factor of 430 was obtained. When a 350 g rat was placed in the resonator at the level of the lower abdomen, the quality factor decreased to 18. The sensitive volume in the loop was visualized with a bottle filled with an aqueous solution of the nitroxide spin probe 3-carbamoyl-2,2,5,5-tetramethyl-3-pyrrolin-1-yloxy (3-CP). The resonator was shown to enable EPR imaging in live rats. Imaging was performed for 3-CP that had been infused intravenously into the rat and its distribution was visualized within the lower abdomen. 相似文献
988.
Yuki Matsumoto Takafumi Yamamoto Kousuke Nakano Hiroshi Takatsu Taito Murakami Kenta Hongo Ryo Maezono Hiraku Ogino Dongjoon Song Craig M. Brown Cdric Tassel Hiroshi Kageyama 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(3):766-769
Square‐planar coordinate Ni2+ ions in oxides are exclusively limited to a low‐spin state (S=0) owing to extensive crystal field splitting. Layered oxychalcogenides A2NiIIO2Ag2Se2 (A=Sr, Ba) with the S=1 NiO2 square lattice are now reported. The structural analysis revealed that the Ni2+ ion is under‐bonded by a significant tensile strain from neighboring Ag2Se2 layers, leading to the reduction in crystal field splitting. Ba2NiO2Ag2Se2 exhibits a G‐type spin order at 130 K, indicating fairly strong in‐plane interactions. The high‐pressure synthesis employed here possibly assists the expansion of NiO2 square lattice by taking the advantage of the difference in compressibility in oxide and selenide layers. 相似文献
989.
Zhaoma Shu Iku Tanaka Azumi Ota Daichi Fushihara Naoko Abe Saki Kawaguchi Kosuke Nakamoto Fumiaki Tomoike Seiichi Tada Yoshihiro Ito Yasuaki Kimura Hiroshi Abe 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(20):6683-6687
Development of intracellular delivery methods for antisense DNA and siRNA is important. Previously reported methods using liposomes or receptor‐ligands take several hours or more to deliver oligonucleotides to the cytoplasm due to their retention in endosomes. Oligonucleotides modified with low molecular weight disulfide units at a terminus reach the cytoplasm 10 minutes after administration to cultured cells. This rapid cytoplasmic internalization of disulfide‐modified oligonucleotides suggests the existence of an uptake pathway other than endocytosis. Mechanistic analysis revealed that the modified oligonucleotides are efficiently internalized into the cytoplasm through disulfide exchange reactions with the thiol groups on the cellular surface. This approach solves several critical problems with the currently available methods for enhancing cellular uptake of oligonucleotides and may be an effective approach in the medicinal application of antisense DNA and siRNA. 相似文献
990.
Naoki Ogiwara Hirokazu Kobayashi Patricia Concepcin Fernando Rey Hiroshi Kitagawa 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(34):11857-11862
We first studied the reactivity of H2O vapor in metal–organic frameworks (MOFs) with Pt nanocrystals (NCs) through the water–gas shift (WGS) reaction. A water‐stable MOF, UiO‐66, serves as a highly effective support material for the WGS reaction compared with ZrO2. The origin of the high catalytic performance was investigated using in situ IR spectroscopy. In addition, from a comparison of the catalytic activities of Pt on UiO‐66, where Pt NCs are located on the surface of UiO‐66 and Pt@UiO‐66, where Pt NCs are coated with UiO‐66, we found that the competitive effects of H2O condensation and diffusion in the UiO‐66 play important roles in the catalytic activity of Pt NCs. A thinner UiO‐66 coating further enhanced the WGS reaction activity of Pt NCs by minimizing the negative effect of slow H2O diffusion in UiO‐66. 相似文献