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161.
Chi Zhang Emiko Kazuma Yousoo Kim 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2019,131(49):17900-17908
Dehalogenative cycloaddition reaction is a powerful strategy to generate new ring scaffolds with π‐conjugated features on a surface, and thus holds great promise toward atomically precise electronic devices or nanomaterials. The ortho‐dihalo substitution provides a good strategy to realize cycloaddition. However, the limited understanding of intermediate states involved hinders mechanistic exploration for further precise design and optimization of reaction products. Now, the evolutions of competing surface‐stabilized radicals and organometallic intermediates in real space were visualized toward the formation of dominant conjugated four‐membered ring connections. From the interplay of scanning tunneling microscopy and density functional theory calculations, the stepwise metal‐mediated dehalogenative cycloaddition pathway is elucidated both experimentally and theoretically. The results provide fundamental insights into the intermediate states involved in on‐surface synthesis. 相似文献
162.
Ohyama K Takemura M 《Proceedings of the Japan Academy. Series B, Physical and biological sciences》2008,84(1):17-23
We here describe in detail the characterization and molecular evolution of group II introns in the mitochondrial genome of the liverwort Marchantia polymorpha. We find that 18 introns of the 25 group II introns can be assigned by their similarities to six clusters, indicating an intra-genomic propagation of one ancestral intron each into the respective clusters in the liverwort mitochondrial genome. Interestingly, the intra-genomic propagation of some of these introns occurred only after the evolutionary separation of the bryophytes from the other clades of plants. Finally we report that the maturase-like sequences in the liverwort group II introns have further evolved by horizontal and independent transposition and substitution by analogous sequences from other fungal introns. 相似文献
163.
164.
Dissipative and Autonomous Square‐Wave Self‐Oscillation of a Macroscopic Hybrid Self‐Assembly under Continuous Light Irradiation 下载免费PDF全文
Tomonori Ikegami Dr. Yoshiyuki Kageyama Kazuma Obara Prof. Sadamu Takeda 《Angewandte Chemie (International ed. in English)》2016,55(29):8239-8243
Building a bottom‐up supramolecular system to perform continuously autonomous motions will pave the way for the next generation of biomimetic mechanical systems. In biological systems, hierarchical molecular synchronization underlies the generation of spatio‐temporal patterns with dissipative structures. However, it remains difficult to build such self‐organized working objects via artificial techniques. Herein, we show the first example of a square‐wave limit‐cycle self‐oscillatory motion of a noncovalent assembly of oleic acid and an azobenzene derivative. The assembly steadily flips under continuous blue‐light irradiation. Mechanical self‐oscillation is established by successively alternating photoisomerization processes and multi‐stable phase transitions. These results offer a fundamental strategy for creating a supramolecular motor that works progressively under the operation of molecule‐based machines. 相似文献
165.
166.
H. Ueno D. Kameda D. Nagae M. Takemura K. Asahi K. Shimada K. Takase T. Sugimoto T. Nagatomo M. Uchida T. Arai T. Inoue A. Yoshimi T. Kawamura K. Narita 《The European physical journal. Special topics》2007,150(1):185-186
Ground-state magnetic-dipole moments (μ) of 30-32Al and
electric quadrupole moments (Q) of 31,32Al have been measured
with the β-NMR method using spin-polarized radioactive-isotope
beams produced in projectile-fragmentation reactions. Beams of
30-32Al were obtained by using RIKEN projectile-fragment
separator RIPS after the fragmentation of 40Ar projectiles at an
energy of E = 95A MeV on a 93Nb target. The obtained
μexp[30-32Al] and
values agree well with shell-model calculations within the sd
shell using the USD interaction. Also, Qexp[31Al]
was found to be small. Thus, we can conclude that these aluminum
isotopes are located outside the island of inversion. 相似文献
167.
The structural phase transition of iodine was observed at about 210 kbar and at room temperature by the high-pressure x-ray diffraction technique using a diamond-anvil cell and a position-sensitive detector. It was found to occur reversibly in both processes of increasing and decreasing pressure. 相似文献
168.
Real-root property of the spectral polynomial of the Treibich–Verdier potential and related problems
Zhijie Chen Ting-Jung Kuo Chang-Shou Lin Kouichi Takemura 《Journal of Differential Equations》2018,264(8):5408-5431
We study the spectral polynomial of the Treibich–Verdier potential. Such spectral polynomial, which is a generalization of the classical Lamé polynomial, plays fundamental roles in both the finite-gap theory and the ODE theory of Heun's equation. In this paper, we prove that all the roots of such spectral polynomial are real and distinct under some assumptions. The proof uses the classical concept of Sturm sequence and isomonodromic theories. We also prove an analogous result for a polynomial associated with a generalized Lamé equation, where we apply a new approach based on the viewpoint of the monodromy data. 相似文献
169.
170.
Triplet-triplet (T-T) energy transfer from acetophenone to naphthalene-d8 has been studied in EPA rigid-glass solution at 77 K by masuring the decay of donor phosphorescence and the rise of acceptor T-T absorption over a wide range of time. The results were analyzed in terms of the theory proposed by Inokuti and Hirayama on the basis of a point molecular model. Two parameters, RO and γ, were determined which are involved in their expression for the rate constant of T-T energy transfer, i.e. n(R) = (1/τD) exp[γ(1?R/RO)], where R and τD denote the donor-acceptor distance and the lifetime of donor triplet in the absence of acceptor, respectively. It was found that, in contrast to the Inokuti-Hirayama theory in which γ is assumed to have a constant value, γ increases significantly as the time (t) after flash excitation of the donor becomes smaller: γ ≈ 25 for t/τD=10-2?1, ≈ 35 for t/τD = 10-3? 10-2, and ≈ 45 for t/τD = 10-4?10-3. This finding suggests that the true rate constant increases with decreasing R value to a greater extent than the n(R) employed by Inokuti and Hirayama. 相似文献