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11.
Mitsuhiko Miyazaki Ryuhei Ohara Kota Daigoku Kenro Hashimoto Jonathan R. Woodward Claude Dedonder Christophe Jouvet Masaaki Fujii 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2015,127(50):15304-15308
Hydrogen‐release by photoexcitation, excited‐state‐hydrogen‐transfer (ESHT), is one of the important photochemical processes that occur in aromatic acids and is responsible for photoprotection of biomolecules. The mechanism is described by conversion of the initial state to a charge‐separated state along the O(N)‐H bond elongation, leading to dissociation. Thus ESHT is not a simple H‐atom transfer in which a proton and a 1s electron move together. Here we show that the electron‐transfer and the proton‐motion are decoupled in gas‐phase ESHT. We monitor electron and proton transfer independently by picosecond time‐resolved near‐infrared and infrared spectroscopy for isolated phenol–(ammonia)5, a benchmark molecular cluster. Electron transfer from phenol to ammonia occurred in less than 3 picoseconds, while the overall H‐atom transfer took 15 picoseconds. The observed electron‐proton decoupling will allow for a deeper understanding and control of of photochemistry in biomolecules. 相似文献
12.
A. Tokuhiro M. Maekawa K. Iizuka K. Hishida M. Maeda 《International Journal of Multiphase Flow》1998,24(8):1383-1406
An experimental investigation on flow around an oscillating bubble and solid ellipsoid with a flat bottom was conducted. A single air bubble (equivalent diameter De=9.12 mm) was attached to a small disk (1 mm) at the end of a needle and suspended across a vertical square channel (100 mm) by wire wherein water flowed downward at a constant flowrate. The solid ellipsoid (De9.1 mm) was suspended across the square channel in the same manner. The equivalent diameter-based Reynolds and Eotvos number range, 1950<Re<2250 and 11<Eo<11.5, placed the bubble in the ‘wobbly’ regime while the flow in its wake was turbulent. A constant flowrate and one bubble size was used such that flow in the wake was turbulent. Velocity measurements of the flow field around the bubble or solid were made using a one CCD camera Digital Particle Image Velocimetry (DPIV) system enhanced by Laser Induced Fluorescence (LIF). The shape of the bubble or solid was simultaneously recorded along with the velocity using a second CCD camera and an Infrared Shadow Technique (IST). In this way both the flow-field and the boundary of the bubble (solid) were measured. The velocity vector plots of flow around and in the wake of a bubble/solid, supplemented by profiles and contours of the average and root-mean-square velocities, vorticity, Reynolds stress and turbulent kinetic energy, revealed differences in the wake flow structure behind a bubble and solid. One of the significant differences was in the inherent, oscillatory motion of the bubble which not only produced vorticity in the near-wake, but as a result of apparent vorticity stretching distributed the turbulent kinetic energy associated with this flow more uniformly on its wake, in contrast to the solid. 相似文献
13.
T. Sato T. Majima Kenro Hashimoto Kouhei Hashimoto Y. Zama J. Matsumoto H. Shiromaru K. Okuno H. Tanuma T. Azuma 《The European Physical Journal D - Atomic, Molecular, Optical and Plasma Physics》2011,63(2):189-194
Microhydrated methylene blue cations,
MB+(H2O)
n
, are produced in an
electrospray ion source and their size-distributions are measured as a function of the
source temperature. A series of
MB+(H2O)
n
ions is observed up to
n ≃ 60. A striking feature observed in the mass spectra is that the
series of hydrated ions starts at n = 4; intensities of
n = 1–3 are extremely suppressed. The absence of
n = 1–3 ions is well explained by the energetics concerning evaporation
processes of water molecules, based on stable structures and the binding energies of
MB+(H2O)
n
ions calculated by DFT
calculations up to n = 5.
MB+(H2O)
n
ions for
n > 4 evaporate a single water molecule
sequentially, while MB+(H2O)4 tends to fragment into
MB+ and (H2O)4 rather than
MB+(H2O)3 and an H2O molecule. We have
observed a clear magic peak at n = 24, which strongly suggests that the
MB+(H2O)24 ion is formed by attaching a neutral
(H2O)20 cage onto an MB+(H2O)4
ion. 相似文献
14.
Fujihara A Miyata C Maekawa A Fuke K Daigoku K Murata N Hashimoto K 《The journal of physical chemistry. A》2007,111(31):7364-7373
Photoelectron spectroscopy (PES) of Na2- (H2O)n (n < or = 6) was investigated to examine the solvation of sodium aggregates in small water clusters. The PES bands for the transitions from the anion to the neutral ground and first excited states derived from Na2 (1(1)Sigmag+) and Na2 (1(3)Sigmau+) shifted gradually to the blue, and those to the higher-excited states correlated to the 3(2)S + 3(2)P asymptote dropped down rapidly to the red and almost degenerated on the 1(3)Sigmau+-type band at n = 4. Quantum chemical calculations for n up to 3 showed that the spectra can be ascribed to structures where one of the Na atoms is selectively hydrated. From the electron distributions, it is found that the Na- -Na+(H2O)n- -type electronic state grows with increasing cluster size, which can be regarded as a sign of the solvation of Na2- with ionization of the hydrated Na. 相似文献
15.
We explain the bundle structures of the Determinant line bundle and the Quillen determinant line bundle considered on the connected component of the space of Fredholm operators including the identity operator in an intrinsic way. Then we show that these two are isomorphic and that they are non-trivial line bundles and trivial on some subspaces. Also we remark a relation of the Quillen determinant line bundle and the Maslov line bundle. 相似文献
16.
Frequency dependence of intermolecular proton spin-lattice relaxation rate [(1/T1)inter(ω)] in neat acetonitrile-d2 was studied. From (1/T1)inter(ω) pair-diffusion constants were determined to be 0.281 × 10?5 and 0.237 × 10?5 cm2 s?1 at 22 and ?32.6°C, respectively. These values differ greatly from the self-diffusion constants. 相似文献
17.
Furumoto H Arai H Kuramitsu Y Saeki Y Gondo T Ishihara T Shimizu T Fujimoto M Nakamura K 《Electrophoresis》2002,23(2):161-166
The effects of various lipoproteins on the growth and the differentiation of cultured normal human keratinocytes were investigated. Primary cultures of human epidermal keratinocytes were obtained from neonatal foreskin, and then added with lipoproteins, very low density lipoprotein (VLDL), low density lipoprotein (LDL), and high density lipoprotein (HDL). Cell growth potential was examined using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) assay. VLDL and LDL enhanced keratinocytes growth and LDL receptor expression at the plasma membrane level. These effects were more remarkably observed in cells cultured with VLDL than in cells cultured with LDL. Apolipoprotein E (ApoE) was highly increased in VLDL treated cells. These results suggest that VLDL binds with high affinity to cell surface receptors and induces cell proliferation. 相似文献
18.
Akihiro Ohta Fusako Yamamoto Yasuhiko Arimura Tokuhiro Watanabe 《Journal of heterocyclic chemistry》1982,19(4):781-784
Some 3,6-dialkyl-1,4-dihydroxy-2,5-dioxopiperazines were conveniently prepared from the corresponding 3,6-dialkyl-2,5-dichloropyrazines via their 1,4-dioxides and 3,6-dialkyl-2,5-dihydroxypyrazine 1,4-dioxides. On the basis of the examination of pmr, tlc, and glc of the 2,5-dioxopiperazines derived from the products, it was clarified that all the products were cis-diastereomers. 相似文献
19.
We examine a class of Grushin type operators Pk where k∈N0 defined in (1.1). The operators Pk are non-elliptic and degenerate on a sub-manifold of RN+?. Geometrically they arise via a submersion from a sub-Laplace operator on a nilpotent Lie group of step k+1. We explain the geometric framework and prove some analytic properties such as essential self-adjointness. The main purpose of the paper is to give an explicit expression of the fundamental solution of Pk. Our methods rely on an appropriate change of coordinates and involve the theory of Bessel and modified Bessel functions together with Weber's second exponential integral. 相似文献
20.
Kimoto T Tanaka K Kawahata M Yamaguchi K Otsubo S Sakai Y Ono Y Ohno A Kobayashi K 《The Journal of organic chemistry》2011,76(12):5018-5025
5,12-Bis(methylthio)tetracene (2) and 5,11-bis(methylthio)tetracene (3) were synthesized. DFT calculations indicate that the HOMO and LUMO energy levels of 2 and 3 are lowered by 0.13-0.24 eV and their HOMO-LUMO energy gaps are reduced by 0.1 eV relative to those of tetracene. X-ray crystallographic data revealed that 2 is arranged as a result of a 1-D slipped-cofacial π-stacking with S-S and S-π interactions, similar to the packing arrangement of 6,13-bis(methylthio)pentacene (1), whereas 3 exhibits a herringbone packing arrangement without S-S interactions. The OFET devices fabricated using spin-coated films of soluble 1 and 2, with a bottom-contact device configuration, exhibited hole mobilities as high as 1.3 × 10(-2) and 4.0 × 10(-2) cm(2) V(-1) s(-1) with current on/off ratios of over 10(5) and 10(4), respectively. 相似文献