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81.
Rajca A Shiraishi K Vale M Han H Rajca S 《Journal of the American Chemical Society》2005,127(25):9014-9020
Hydrocarbon diradical 1, a new stable, 3-fold symmetric analogue of trimethylenemethane (TMM) with no heteroatom perturbation, is prepared and studied. Such diradicals should provide new building blocks for high-spin hydrocarbon polyradicals with very strong net ferromagnetic coupling. Magnetic studies (SQUID) and EPR spectroscopy indicate that 1 in tetrahydrofuran-d8 (THF-d8) possesses a triplet (S = 1) ground state, with strong ferromagnetic coupling. After annealing at room temperature, the EPR spectra of 1 (approximately 0.02 M in frozen THF-d8) consist of a single narrow resonance (deltaH(pp) < 1 G), and intermolecular antiferromagnetic coupling is increased by 1 order of magnitude. This behavior is consistent with the presence of exchange narrowing, thus suggesting aggregation of 1 in THF-d8. Blue solutions of 1 in THF-d8 possess a strong UV-vis absorption band at lambda(max) approximately 640 nm. Diradical 1 in THF-d8 is stable (or persistent) at room temperature, with no detectable decomposition for at least 2 days. 相似文献
82.
Yokoyama K Teranishi Y Toya Y Shirai T Fukuda Y Aoyama M Akahane Y Inoue N Ueda H Yamakawa K Yokoyama A Yamada H Yabushita A Sugita A 《The Journal of chemical physics》2004,120(20):9446-9449
Optimal laser control for ultrafast selection of closely lying excited states whose energy separation is smaller than the laser bandwidth is reported on the two-photon transition of atomic cesium; Cs(6S-->7D(J), J=5/2 and 3/2). Selective excitation was carried out by pulse shaping of ultrashort laser pulses which were adaptively modulated in a closed-loop learning system handling eight parameters representing the electric field. Two-color fluorescence from the respective excited states was monitored to measure the selectivity. The fitness used in the learning algorithm was evaluated from the ratio of the fluorescence yields. After fifty generations, a pair of nearly transform-limited pulses were obtained as an optimal pulse shape, proving the effectiveness of the "Ramsey fringes" mechanism. The contrast of the selection ratio was improved by approximately 30% from the simple "Ramsey fringes" experiment. 相似文献
83.
The RBCC (RING finger, B-box type zinc finger, coiled-coil domain) motif family contains a large number of proteins implicated in many cellular processes, including vesicle exocytosis. The acrosome reaction, the sperm exocytotic event that is required for fertilization, involves essentially the same process of intracellular membrane fusions as vesicular exocytosis in somatic cells. We have previously isolated a haploid-germ-cell-specific gene designated haprin, which encodes a RBCC motif protein that plays a role in the acrosome reaction of sperm by mediating protein complex formation via the RBCC motif. In this review, we describe the potential role of Haprin in the molecular mechanisms of acrosome reaction, as compared with some other RBCC proteins. The conserved structure and localization of the Haprin protein in human and mouse suggest an indispensable role for Haprin in the functioning of mammalian sperm. 相似文献
84.
Tomoya Kitazume Kouichi Kawai Takashi Nihei Noriaki Miyake 《Journal of fluorine chemistry》2005,126(1):59-62
Synthetic utility of microreactors and highly stereoselective isomerization (>99:<1) of terminal difluoromethylated alkenes to (E)-difluoromethylated alkenes with TBAF in DMF, are described. 相似文献
85.
Jens R. Stellhorn Shinya Hosokawa Naohisa Happo Hiroo Tajiri Tomohiro Matsushita Kenichi Kaminaga Tomoteru Fukumura Tetsuya Hasegawa Koji Kimura Kouichi Hayashi 《Surface and interface analysis : SIA》2019,51(1):70-73
We report on the characterization of a thin film of yttrium oxide by X-ray fluorescence holography. The sample has a layered structure with an YO base layer and an oxidized Y2O3 surface. Both layers are clearly observed in the atomic image reconstructions, and their local structure is analyzed. We show that by using incident energies close to the absorption edge of the fluorescing atom, it becomes possible to observe the thin surface layer clearly, even next to a base layer containing the same fluorescing element. 相似文献
86.
Kouichi Kawashima Jin Zhu Ding Hideo Hosono Yoshihiro Abe 《Phosphorus, sulfur, and silicon and the related elements》2013,188(1-4):157-160
Abstract Effects of photodoping and thermal doping of silver into sputtered amorphous red phosphorus films (a-Pred) on the electrical properties are studied. The d. c. efectrical conductivity of the photodoped a-pred at room temperature is about 1×10?5 Scm?1 which is a very high value comparing with that of the undoped a-pred (1×10?14 Scm?1). The activation energy for the conduction of the photodoped a-Pred is lower than that of the a-pred. In contrast, the activation energy of the thermally doped a-pred is essentially the same as that of the undoped a-pred. SEM-EDX analyses show that colloidal silver was deposited in the thermally doped a-pred but not in the photodoped a-pred. It seems that the photo-doping involves the ionization process of silver by illumination, i.e., Ago → Ag+ + e?. 相似文献
87.
The effect of the polarization electric field on helix-unwinding in a thin planar chiral smectic C liquid-crystal cell is studied by using the nematic-like expression for the elastic deformation free-energy density. It is found that the elongation of the helical pitch when the cell thickness decreases is greater when the spontaneous polarization is larger. This is due to the Coulomb repulsion between polarization charges concentrated at ± 2π disclinations. 相似文献
88.
The possibility of multi-valued optical disk memory by using a convex-shaped recording mark fabricated by two-photon absorption is investigated. We fabricate a numerical model for convex-shaped recording marks and evaluate the signal characteristics in terms of the signal-to-noise ratio (SNR). The numerical results show that 6 bit data can be realized when the acceptable average SNR is 2 and a length of the mark is 4T. 相似文献
89.
Matsunaga T Kojima R Yamada N Kifune K Kubota Y Tabata Y Takata M 《Inorganic chemistry》2006,45(5):2235-2241
GeTe(1-x)-Sb2Te3(x) sputtered amorphous film was crystallized into a simple NaCl-type structure through instantaneous laser irradiation over a wide composition range from x = 0 to at least 2/3. When the ratio of Sb2Te3 increases, a vacancy is generated at every Na site for two Sb atoms. The fraction of vacancies, v(x), changes according to x/(1 + 2x), and the cubic root unit cell volume varies with a strong correlation to v(x). Through these created vacancies, valence electrons provided by adjacent Ge/Sb and Te atoms remain constant regardless of the composition, ensuring that these electrons occupy predominantly the bonding molecular orbitals. This results in crystal chemical stability, with the closed shell p-p bondings in the valence electrons arranging the crystal's atomic configuration into an NaCl-type structure. 相似文献
90.
Teranishi Y Ohtsuki Y Hosaka K Chiba H Katsuki H Ohmori K 《The Journal of chemical physics》2006,124(11):114110
We numerically propose a way to perform quantum computations by combining an ensemble of molecular states and weak laser pulses. A logical input state is expressed as a superposition state (a wave packet) of molecular states, which is initially prepared by a designed femtosecond laser pulse. The free propagation of the wave packet for a specified time interval leads to the specified change in the relative phases among the molecular basis states, which corresponds to a computational result. The computational results are retrieved by means of quantum interferometry. Numerical tests are implemented in the vibrational states of the B state of I2 employing controlled-NOT gate, and 2 and 3 qubits Fourier transforms. All the steps involved in the computational scheme, i.e., the initial preparation, gate operation, and detection steps, are achieved with extremely high precision. 相似文献