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971.
A Galerkin scheme is presented for a class of conservative nonlinear dispersive equations, such as the Camassa–Holm equation and the regularized long wave equation. The scheme has two advantageous features: first, it is conservative in that it keeps the discrete analogue of the continuous energy conservation property in the original equations; second, it can be formulated only with cheap H1-elements even if the original equations include third derivative uxxx. Numerical experiments confirm the stability and effectiveness of the proposed scheme. 相似文献
972.
973.
Yoshio Kobayashi Satoshi Ishida Kazuaki Ihara Yusuke Yasuda Toshiaki Morita Shinji Yamada 《Colloid and polymer science》2009,287(7):877-880
This paper describes a method for polypyrrole (PPy) coating of metallic Cu nanoparticles in aqueous solution in atmosphere.
Colloid solution of Cu nanoparticles was prepared by reducing Cu ions with the use of hydrazine in an aqueous solution dissolving
citric acid and cetyltrimethylammonium bromide as stabilizers. The PPy coating was performed by polymerizing pyrrole with
the use of hydrogen peroxide as an initiator in an aqueous colloid solution of the Cu nanoparticles. Ultraviolet–visible extinction
measurements, transmission electron microscopy observation, and X-ray diffraction measurements revealed that the metallic
Cu nanoparticles with a size of 27.6 ± 11.1 nm were coated with PPy. The obtained PPy-coated Cu particles were chemically
stable even in atmosphere. 相似文献
974.
975.
Yoshiyuki Ogasawara Sayaka Uchida Dr. Kazuya Yamaguchi Dr. Noritaka Mizuno Prof. Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2009,15(17):4343-4349
Mix and calcinate : The tin–tungsten mixed oxide (Sn–W oxide) prepared by calcination of the Sn–W hydroxide at 800 °C acts as an effective and reusable solid catalyst for C? C bond‐forming reactions, such as the cyclization of citronellal, the Diels–Alder reaction, and the cyanosilylation of carbonyl compounds with trimethylsilyl cyanide (see scheme). The observed catalysis was truly heterogeneous, and the recovered catalyst could be reused without loss of its high catalytic performance.
976.
Michiko Sasaki Dr. Hidaka Ikemoto Masatoshi Kawahata Dr. Kentaro Yamaguchi Prof. Kei Takeda Prof. Dr. 《Chemistry (Weinheim an der Bergstrasse, Germany)》2009,15(18):4663-4666
Don't get trapped : The effect of conjugating electron‐withdrawing groups and α‐anion‐stabilizing heteroatom substituents on configurational stability of chiral carbanions through a double bond was examined on the basis of extent of chirality transfer in intramolecular trapping in [2,3]‐Wittig rearrangement of chiral 3‐substituted 1‐propenyloxy‐1‐phenyl‐2‐propen‐1‐yl carbanions (see scheme).
977.
Satoshi Yamaguchi Tomohiro Uchimura Tomoko Imasaka Totaro Imasaka 《Rapid communications in mass spectrometry : RCM》2009,23(19):3101-3106
Triacetone triperoxide (TATP), which is used as an explosive in acts of terrorism, was measured by means of gas chromatography/multiphoton ionization/time‐of‐flight mass spectrometry using a deep‐ultraviolet (deep‐UV) femtosecond laser as an ionization source. The fragmentation process was investigated by changing the intensity of the laser at the center axis of a molecular beam. A molecular ion was observed using a femtosecond laser, and the ratio of the intensities of the molecular and fragment ions decreased as the intensity of the laser increased. These results suggest that TATP can be efficiently ionized using a deep‐UV, ultrashort optical pulse. Furthermore, fragmentation was accelerated by excess energy supplied through higher‐order multiphoton processes under a strong radiation field. The detection limits obtained using the molecular ion and two dominant fragment ions, C2H3O+ and CH, were determined to be 670, 83 and 150 pg, respectively. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
978.
Channelrhodopsins (ChR1 and ChR2) are directly light‐gated ion channels acting as sensory photoreceptors in the green alga Chlamydomonas reinhardtii. These channels open rapidly after light absorption and both become permeable for cations such as H+, Li+, Na+, K+ and Ca2+. Km for Ca2+ is 16.6 mm in ChR1 and 18.3 mm in ChR2 whereas the Km values for Na+ are higher than 100 mm for both ChRs. Action spectra of ChR1 peak between 470 and 500 nm depending on the pH conditions, whereas ChR2 peaks at 470 nm regardless of the pH value. Now we created two chimeric ChRs possessing helix 1–5 of ChR1 and 6, 7 of ChR2 (ChR1/25/2), or 1, 2 from ChR1 and 3–7 from ChR2 (ChR1/22/5). Both ChR‐chimera still showed pH‐dependent action spectra shifts. Finally, a mutant ChR1E87Q was generated that inactivated only slowly in the light and showed no spectral shift upon pH change. The results indicate that protonation/deprotonation of E87 in helix 1 alters the chromophore polarity, which shifts the absorption and modifies channel inactivation accordingly. We propose a trimodal counter ion complex for ChR1 but only a bimodal complex for ChR2. 相似文献
979.
Nakata Y Honda Y Ninomiya S Seki T Aoki T Matsuo J 《Journal of mass spectrometry : JMS》2009,44(1):128-136
The importance of imaging mass spectrometry (MS) for visualizing the spatial distribution of molecular species in biological tissues and cells is growing. We have developed a new system for imaging MS using MeV ion beams, termed MeV-secondary ion mass spectrometry (MeV-SIMS) here, and demonstrated more than 1000-fold increase in molecular ion yield from a peptide sample (1154 Da), compared to keV ion irradiation. This significant enhancement of the molecular ion yield is attributed to electronic excitation induced in the near-surface region by the impact of high energy ions. In addition, the secondary ion efficiency for biologically important compounds (>1 kDa) increased to more than 10(10) cm(-2), demonstrating that the current technique could, in principle, achieve micrometer lateral resolution. In addition to MeV-SIMS, peptide compounds were also analyzed with cluster-SIMS and the results indicated that in the former method the molecular ion yields increased substantially compared to the latter. To assess the capability of MeV-SIMS to acquire heavy-ion images, we have prepared a micropatterned peptide surface and successfully obtained mass spectrometric imaging of the deprotonated peptides (m/z 1153) without any matrix enhancement. The results obtained in this study indicate that the MeV-SIMS technique can be a powerful tool for high-resolution imaging in the mass range from 100 to over 1000 Da. 相似文献
980.
Hiroaki Kitagishi Dr. Yasuaki Kakikura Hiroyasu Yamaguchi Dr. Koji Oohora Akira Harada Prof. Dr. Takashi Hayashi Prof. Dr. 《Angewandte Chemie (International ed. in English)》2009,48(7):1170-1170
Supramolecular protein polymers consisting of cytochrome b562 monomers with heme covalently attached to the protein surface are presented by T. Hayashi and co‐workers in their Communication on page 1271 ff. Not only one‐dimensional hemoprotein fibers with submicrometer lengths have been prepared, but when a heme triad was added as a pivot molecule, two‐dimensional protein assembly networks resulted, which cover over 100 square micrometers.