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31.
Organocatalytic direct asymmetric aldol reactions in water 总被引:2,自引:0,他引:2
Mase N Nakai Y Ohara N Yoda H Takabe K Tanaka F Barbas CF 《Journal of the American Chemical Society》2006,128(3):734-735
We have developed direct asymmetric cross-aldol reactions that can be performed in water without addition of organic solvents. A bifunctional catalyst with a long hydrophobic alkyl chain efficiently catalyzed the reactions and afforded the desired aldol products in excellent yield with high enantiomeric excess, even when only an equal molar ratio of the donor and acceptor was used. These results reveal an effective design strategy for the development of aqueous organocatalytic systems. 相似文献
32.
We investigate the dynamics of probability distributions of an initially one-mode coherent field interacting with a four-state molecular system, which is a single magnet with a tunneling across an anisotropic barrier, using a numerically exact approach. The population for each state, the phase properties of and
, and
), the entropy are calculated for a model system. The model predicts that the molecule and field become asymptotically disentangled at half of the revival time, and that optical Schrödinger-cat and magnetic Schrödinger-cat states are generated.This paper was originally presented at the 5th International Conference on NEAR FIELD OPTICS and RELATED TECHNOLOGIES (NFO-5), which was held on December 6–10, 1998 at Coganoi Bay Hotel, Shirahama, Japan, in cooperation with the Japan Society of Applied Physics and Mombusho Grant-in Aid for Scientific Research on Priority Areas “Near-field Nano-optics” Project, sponsored by Japan Society for the Promotion of Science. 相似文献
33.
From the viewpoint that thermodynamic study is essential to elucidate the structure and properties of thin liquid films, thermodynamic equations based on a new convention and employing pressure as a thermodynamic variable are developed for adsorption at film interfaces of a plane-parallel film. The equations together with quasi-thermodynamic ones correlate the dependence of film tension on concentration, temperature, pressure, and disjoining pressure to film density, entropy and volume changes associated with adsorption, and thermodynamic film thickness, respectively. Based on the formulation adopting pressure as a variable, equations are also derived for the differences in thermodynamic quantity between the film and the bulk interfaces coexisting at equilibrium.This revised version was published online in October 2004.Due to an unfortunate error Figure 1 has been omitted in the first version of the article which was published online first on April 23, 2004. 相似文献
34.
Inelastically tunneled electrons from a scanning tunneling microscope (STM) were used to induce vibrationally mediated motion of a single cis-2-butene molecule among four equivalent orientations on Pd(110) at 4.8 K. The action spectrum obtained from the motion clearly detects more vibrational modes than inelastic electron tunneling spectroscopy with a STM. We demonstrate the usefulness of the action spectroscopy as a novel single molecule vibrational spectroscopic method. We also discuss its selection rules in terms of resonance tunneling. 相似文献
35.
Tsuchida H 《Optics letters》2011,36(5):681-683
I propose and demonstrate the use of the recirculating delayed self-heterodyne (DSH) method for measuring FM noise power spectral densities (PSDs), which are the most fundamental measure characterizing the spectral purity of laser sources. By analyzing the DSH beat signals with 1, 10, and 160?km delays, the FM noise PSD of a narrow-linewidth fiber laser is evaluated for Fourier frequency range between 10?Hz and 100?kHz, which exhibits flicker noise as the dominant contribution. 相似文献
36.
Yasuhito Ohta J. Maki Hidemi Nagao Kiyoshi Nishikawa 《International journal of quantum chemistry》2004,97(5):891-895
The ionization process of the hydrogen atom in two-color laser field is investigated based on non–Born-Oppenheimer one-dimensional model. In this model, both electron and nucleus are described by the time-dependent Hartree equations. By numerically solving the equations, the influence of the relative phase ϕ of the laser field with the spatial distribution of electron and nucleus is investigated. For ϕ = 0, the electron is moved to the direction in which the maximum of the asymmetric combined electric field pointed. For ϕ = π/2, the electron is shown to be pulled in the opposite direction. © 2003 Wiley Periodicals, Inc. Int J Quantum Chem, 2004 相似文献
37.
Tsuruoka T Takahashi R Nakamura T Fujii M Akamatsu K Nawafune H 《Chemical communications (Cambridge, England)》2008,(14):1641-1643
The significant fluorescence enhancement of immobilized CdTe nanocrystals through chemical surface modifications is described, enabling us to fabricate stable, highly luminescent thin films and patterns of nanocrystal mono- and mutilayers. 相似文献
38.
Atomic beam-induced fluorination of polyimide and its application to site-selective Cu metallization
Tagawa M Maeda K Kajita T Yokota K Akamatsu K Nawafune H 《Langmuir : the ACS journal of surfaces and colloids》2007,23(23):11351-11354
Metallization methods of polyimide by hyperthermal atomic oxygen and atomic fluorine beams were developed. An atomic fluorine beam with a translational energy of 6.2 eV modified the wettability of polyimide surfaces to provide an advancing water contact angle of 132 degrees. It was confirmed that in-air storage for 2 months did not alter the hydrophobic property created by the atomic fluorine beam. This stable beam-induced surface fluorination technique was then applied to site-selective electroless Cu plating on polyimide. It was demonstrated that changing the exposure sequence could create both positive- and negative-type plating processes. 相似文献
39.
We report an ultrafast cross phase modulation (XPM) effect in intersubband transition (ISBT) of InGaAs/AlAs/AlAsSb coupled quantum wells, where the ISBT absorption of a transverse-magnetic mode pump signal induces phase modulation of a transverse-electric mode probe signal. Using waveguide-type ISBT devices, we have achieved XPM-based 10 Gbit/s wavelength conversion with a power penalty of 2.53 dB. Also, we propose XPM-based signal processing circuits for gate switching and modulation format conversion. 相似文献
40.
Akamatsu K Fukumoto Y Taniyama T Tsuruoka T Yanagimoto H Nawafune H 《Langmuir : the ACS journal of surfaces and colloids》2011,27(19):11761-11766
We report a fully additive-based electrochemical approach to the site-selective deposition of silver on a polyimide substrate. Using a cathode coated with ion-doped precursor polyimide layers, patterns of metal masks used as anodes were successfully reproduced at the cathode-precursor interface through electrochemical and ion-exchange reactions, which resulted in the generation of silver patterns on the polyimide films after subsequent annealing and removal from the substrate. Excellent interfacial adhesion was achieved through metal nanostructures consisting of interconnecting silver nanoparticles at the metal-polymer interface, which are electrochemically grown "in" the precursor layer. This approach is a resist- and etch-free process and thus provides an effective methodology toward lower-cost and high-throughput microfabrication. 相似文献