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排序方式: 共有183条查询结果,搜索用时 15 毫秒
61.
62.
Rajasekhar?MedapalliEmail author Ilya?Razdolski Matteo?Savoini Ali Reza?Khorsand Alexandra?M.?Kalashnikova Arata?Tsukamoto Akiyoshi?Itoh Andrei?Kirilyuk Alexey?V.?Kimel Theo?Rasing 《The European Physical Journal B - Condensed Matter and Complex Systems》2013,86(4):183
The ability of a femtosecond laser pulse to manipulate and reverse the magnetization in a ferrimagnetic Gd24Fe66.5Co9.5 thin film was studied experimentally as a function of temperature. For a fixed energy of the laser pulse, the dynamics of magnetization showed different behavior depending on whether the sample temperature was below or above the magnetization compensation point (T M ). The conditions for full ultrafast demagnetization and magnetization reversal were easily achieved below T M , while the same laser excitation caused just 50% demagnetization above T M . This interesting change in magnetization dynamics is qualitatively explained in terms of effective changes in the magnitudes of magnetizations of atomic sublattices. 相似文献
63.
Nakazawa J Ogiwara H Kashiwazaki Y Ishii A Imamura N Samejima Y Hikichi S 《Inorganic chemistry》2011,50(20):9933-9935
The nickel(II) complex [Ni(Tp(Me2)) (SC(6)H(4)NO(2))] [1a; Tp(Me2) = hydrotris(3,5-dimethylpyrazol-1-yl)borate] reacts with O(2) to form the ligand oxygenation product ArSO(2)(-) in MeCN, and also 1a catalyzes the oxygenation of external substrates such as triphenylphosphine. The reactivity may correlate to the unique quinoid-like resonance structure of the thiophenolate ligand. The structure is stabilized by a p-nitro group and induced by coordination of MeCN. 相似文献
64.
Matsuda A Fushitani M Takahashi EJ Hishikawa A 《Physical chemistry chemical physics : PCCP》2011,13(19):8697-8704
The visualization of ultrafast isomerization of deuterated acetylene dication (C(2)D(2)(2+)) is demonstrated by time-resolved Coulomb explosion imaging with sub-10 fs intense laser pulses (9 fs, 0.13 PW cm(-2), 800 nm). The Coulomb explosion imaging monitoring the three-body explosion process, C(2)D(2)(3+)→ D(+) + C(+) + CD(+), as a function of the delay between the pump and probe pulses revealed that the migration of a deuterium atom proceeds in a recurrent manner; One of the deuterium atoms first shifts from one carbon site to the other in a short timescale (~90 fs), and then migrates back to the original carbon site by 280 fs, in competition with the molecular dissociation. Correlated motion of the two deuterium atoms associated with the hydrogen migration and structural deformation to non-planar geometry are identified by the time-resolved four-body Coulomb explosion imaging, C(2)D(2)(4+)→ D(+) + C(+) + C(+) + D(+). 相似文献
65.
Direct synthesis of cup-stacked carbon nanofiber microspheres by the catalytic pyrolysis of poly(ethylene glycol) 总被引:1,自引:0,他引:1
Ko S Takahashi Y Sakoda A Sakai Y Komori K 《Langmuir : the ACS journal of surfaces and colloids》2012,28(23):8760-8766
Uniformly sized microspheres tangled with cup-stacked carbon nanofibers (CSCNFs) were directly synthesized by the pyrolysis of poly(ethylene glycol) (PEG) with a nickel catalyst. A PEG/Ni membrane was prepared on a silicon wafer surface by heating it to 750 °C at a heating rate of 15 °C min(-1). The wafer was heated to a temperature of 400 °C and was held at that temperature for 1 h before raising the temperature to 750 °C for 10 min to form the CSCNF microspheres. The final CSCNF microspheres and the intermediates were evaluated using scanning electron microscopy, transmission electron microscopy, X-ray diffractometry, and Raman spectroscopy to elucidate the growth mechanism. Furthermore, the CSCNF microspheres were successfully dispersed and maintained their spherical shape in an aqueous solution containing 0.5% Nafion. The CSCNF microspheres have the potential to work as a sophisticated carrier with high adsorption and fast electron-transfer exchange properties based on the graphene edges of the nanofiber surface. 相似文献
66.
The Coulomb explosion dynamics of H2S, H2S3+-->H+ +S+ + H+, in ultrashort intense laser fields (12 fs, approximately 2 x 10(14) W/cm2) is studied by the coincidence momentum imaging of the three fragment ions. Different electronic and nuclear responses are identified depending on the direction of laser polarization epsilon in the molecular frame. The dependence can be interpreted in terms of the electronic and bonding characters of charge transfer states of H2S coupled to the electronic ground state. 相似文献
67.
The surface design used for reducing nonspecific biofouling is one of the most important issues for the fabrication of medical devices. We present here a newly synthesized a carbohydrate-immobilized phosphorylcholine polymer for surface modification of medical devices to control the interface with living cells. A random copolymer composed of 2-methacryloyloxyethyl phosphorylcholine (MPC), n-butyl methacrylate (BMA), and 2-lactobionamidoethyl methacrylate (LAMA) was synthesized by conventional radical polymerization. The monomer feeding ratio in the copolymer was adjusted to 24/75/1 (MPC/BMA/LAMA). The copolymer (PMBL1.0) could be coated by solvent evaporation from an ethanol solution.Cells of the human hepatocellular liver carcinoma cell line (HepG2) having asialoglycoprotein receptors (ASGPRs) were seeded on PMBL1.0 or poly(BMA) (PBMA)-coated PET plates. On PBMA, many adherent cells were observed and were well spread with monolayer adhesion. HepG2 adhesion was observed on PMBL1.0 because the cell has ASGPRs. Furthermore, some of the cells adhering to PMBL1.0 had a spheroid formation and similarly shaped spheroids were scattered on the surface. According to confocal laser microscopic observation after 96 h cultivation, it was found that albumin production preferentially occurred in the center of the spheroid. The albumin production of the cells that adhered to PBMA was sparse. The amount of albumin production per unit cell that adhered to PMBL1.0 was determined by ELISA and was significantly higher than that which adhered to PBMA.Long-term cultivation of HepG2 was also performed using hollow fiber mini-modules coated with PMBL1.0. The concentration of albumin produced from HepG2 increased continuously for one month. In the mini-module, the function of HepG2 was effectively preserved for that period. On the hollow fiber membrane, spheroid formation of HepG2 cells was also observed.In conclusion, PMBL1.0 can provide a suitable surface for the cultivation of hepatocytes and has great potential for producing reliable bioartificial liver (BAL) devices. 相似文献
68.
Tsuru Kanji Hayakawa Satoshi Ohtsuki Chikara Osaka Akiyoshi 《Journal of Sol-Gel Science and Technology》1998,13(1-3):237-240
An ethanol (EtOH) solution of polymerized vinyltrimethoxysilane (VTMS), about 20-mers, was mixed with an aqueous solution of calcium acetate (Ca(OAc)2) and refluxed in N2 for 1 h to give sols of a typical composition VTMS : H2O : EtOH : Ca(OAc)2 = 1 : 9 : 8 : 0.05 (mol). Homogeneous films could be produced, by dip-coating, on Nylon6® and soda-lime glass, but not on polypropylene or polytetrafluoroethylene. The gel films did not deposit apatite within 14 days of soaking in a simulated body fluid whereas films abraded with emery paper as well as bulk gels deposited apatite on the surfaces within 7 days, indicating the present gel was suitable for bioactive coatings on Nylon6® 相似文献
69.
Kin-ya Akiba Akiyoshi Shimizu Hideyuki Ohnari Katsuo Ohkata 《Tetrahedron letters》1985,26(27):3211-3214
Tributylstibine is an efficient reagent for debromination of phenacyl and arylmethyl bromides. The mechanistic difference between stibine and phosphine is discussed briefly. 相似文献
70.
Seiji Isoda Akiyoshi Kawaguchi Ken-Ichi Katayama 《Journal of Polymer Science.Polymer Physics》1984,22(4):669-679
The crystal structure of poly(p-xylylene), as polymerized, is the α form. This transforms irreversibly to the β from by annealing or drawing. To clarify the mechanism of this transition, structural changes of the α and β crystals were examined with a high-temperature stage in the electron microscope. Two high-temperature phases, β1 and β2, were found and their structures were analyzed. In these structures lattice distortions due to rotational and translational motions of chains are in troduced, especially in the β2 form. The α → β transition is induced through such a disordered phase. The statistical arrangement of a molecule in the β-form unit cell results from freezing the disorder in the high-temperature phases. 相似文献