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171.
Masanori Hara Naomi Hatakeyama Kuniaki Watanabe Katsunori Mori 《Journal of magnetism and magnetic materials》2009,321(5):423-428
The magnetization of GdCu induced by hydrogen uptake was measured within the temperature range of 4.2 to 300 K, occurring phase changes were followed by X-ray diffraction measurements at ambient temperature. The prepared GdCu powder of CsCl-type structure readily absorbed hydrogen at ambient temperature, where hydrogen pressure was below 100 kPa. Hydrogenation changed the magnetism of GdCu in a complex manner from an antiferromagnetic-like type to a paramagnetic-like one. The changes in magnetic properties of GdCu by hydrogenation are governed by hydrogen-induced disproportionation. Within the composition range 0<[H]/[GdCu]<1, GdCu disproportionated according to 2GdCu+H2→GdH2+GdCu2 . The magnetization was evaluated by the expression χtotal=(1-x)χGdCu+(x/2)(χGdH2+χGdCu2). GdCu hydride was not observed. Hydrogenation beyond [H]/[GdCu]>1 gave rise to the disproportionation of GdCu2 causing the change in magnetization. 相似文献
172.
Makoto Tsunoda Masanori Yamagishi Kazuhiro Imai Teruyuki Yanagisawa 《Analytical and bioanalytical chemistry》2009,394(4):947-952
A highly sensitive determination method was established for catecholamines (norepinephrine (NE), epinephrine, and dopamine)
with high-performance liquid chromatography-peroxyoxalate chemiluminescence reaction detection. In this study, the method
was applied to mouse plasma, and it was determined that only 10 μl of mouse plasma was necessary for the selective and reproducible
determination of catecholamines. Studies were then conducted in acute cardiovascular effects of sodium nitroprusside, nicardipine,
captopril (angiotensin-converting enzyme (ACE) inhibitor), candesartan, and olmesartan (type 1 angiotensin receptor antagonists
(AT1 antagonists)) by this method. Sodium nitroprusside and nicardipine elevated plasma NE concentrations significantly, whereas
the ACE inhibitor and the AT1 antagonists did not change plasma NE concentrations in anesthetized mice. These results suggested that angiotensin II-induced
augmentation may be mainly carried through the central baroreflex pathway. 相似文献
173.
Abe M Hattori M Takegami A Masuyama A Hayashi T Seki S Tagawa S 《Journal of the American Chemical Society》2006,128(24):8008-8014
A detailed study of the regioselectivity of 1,2-oxygen migration was conducted using the unsymmetrically substituted singlet 2,2-dialkoxy-1,3-diarylcyclopentane-1,3-diyls 5. The alkoxy group selectively migrates to the electron-donating p-methoxyphenyl-substituted carbon. The regioselective migration of oxygen clearly indicates a hyperconjugative resonance structure, that is, zwitterionic characteristics, in singlet 2,2-dialkoxy-1,3-diyls. This represents the first attempt to experimentally probe the contribution of hyperconjugation to stabilizing the singlet state. 相似文献
174.
Nakamura K Zhang X Kuramitsu Y Fujimoto M Yuan X Akada J Aoshima-Okuda M Mitani N Itoh Y Katoh T Morita Y Nagasaka Y Yamazaki Y Kuriki T Sobel A 《Journal of chromatography. A》2006,1106(1-2):181-189
Two-dimensional gel electrophoresis (2-DE) and tandem mass spectrometry were successfully used for determination of a phosphorylation site of stathmin induced by heat stress to Jurkat cells of a human T lymphoblastic cell line. The cells were incubated for 30 min at 41 degrees C up to 45 degrees C in a serum free 4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid (HEPES) buffered culture medium. The intracellular soluble proteins were separated by 2-DE, and some of the proteins increased their abundance by heat stress. Those proteins were identified to be calmodulin, protein kinase C substrate, thymosin beta-4 and F-actin capping protein beta-subunit by peptide mass fingerprinting (PMF) with matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS). On the contrary, protein phosphatase 2C gamma-isoform, nucleophosmin, translationally controlled tumor protein, Rho GDP-dissociation inhibitor-1, eukaryotic translation initiation factors 5A and 3A subunit 2, ubiquitin-like protein SMT 3B and chloride intracellular channel protein-1 were decreased their abundance. A protein spot of M(r) 18,000 and pI 5.9 was markedly increased at temperatures higher than 43 degrees C at which the cells were led to apoptosis. The spot was identified to be stathmin of a signal relay protein which has a function of sequestering microtubule. MALDI-quadrupole ion trap (QIT)-TOF-MS/MS and immunoblotting with a monoclonal antibody specific for a phosphorylation site of stathmin showed that the spot was a phosphorylated stathmin at serine 37 (Ser 37). The phosphorylation was suppressed by treatment of cells with olomoucine of an inhibitor specific for cyclin dependent kinase (Cdk-1). These results strongly suggest that heat stress activates Cdk-1 which phosphorylates Ser 37 on the stathmin molecule. The phosphorylation may cause the functional loss of stathmin for dynamic microtubule assembly and leads Jurkat cells to cell cycle arrest and apoptosis. 相似文献
175.
Kunishima M Tokaji M Matsuoka K Nishida J Kanamori M Hioki K Tani S 《Journal of the American Chemical Society》2006,128(45):14452-14453
Mere chemical generation of ceramide and related double-chain lipids in the membrane of small unilamellar vesicles (SUVs) induces fusion of the vesicles. The lipids can be successfully prepared by dehydrocondensation between single-chain lipids (fatty acids and sphingosine or its analogues) in a lipid bilayer of the SUV by using a combination of 2-chloro-4,6-dimethoxy-1,3,5-triazine and amphiphilic tertiary amine catalysts, a process that can be compared to a successive enzyme model system for a fatty acyl-CoA synthetase followed by acyltransferase. The SUV spontaneously undergoes membrane fusion upon this internal chemical stimulation by the artificial enzyme system. 相似文献
176.
Coherent phase control of the photodissociation reaction of the dimethylsulfide has been achieved by means of quantum-mechanical interference between one- and three-photon transitions. Dimethylsulfide was irradiated by fundamental and frequency-tripled outputs of a visible laser (600.5-602.5 nm), simultaneously to yield CH3S+ and CH3SCH2+ fragment ions. The branching ratio of the two product channels could be modulated with variation of the phase difference between the light fields. This accounted for the difference between the molecular phases of the two product channels. The phase lag was observed to have a maximum value of 8 degrees at 601.5 nm. This is the first result of a selective bond breaking in a polyatomic molecule by the coherent phase control. 相似文献
177.
Sakamoto M Tachikawa T Fujitsuka M Majima T 《Langmuir : the ACS journal of surfaces and colloids》2006,22(14):6361-6366
Gold nanoparticles (AuNps) were fabricated in a poly(vinyl alcohol) (PVA) film using the photochemically generated benzophenone ketyl radical and PVA radical by laser irradiation as a reducing agent. The measurements of the surface plasmon band of AuNps indicated that AuNps continued growing in the PVA film for several hours or days after the laser irradiation. The formation process of AuNps in the PVA film was investigated by using laser flash photolysis and UV-vis absorption spectroscopy. Additive doping (formic acid or sodium 2-mercaptoethanesulfonate) in the PVA film dramatically accelerated or inhibited the formation rate of the AuNps, respectively. The doping of formic acid accelerated the formation rate of the AuNps by a factor of 10-20. On the contrary, doping of 2-mercaptoethanesulfonate inhibited the formation of AuNps. The mechanisms of the acceleration and inhibition were investigated by using laser flash photolysis. The effects of additives on the formation process of AuNps are discussed. 相似文献
178.
Koumura N Wang ZS Mori S Miyashita M Suzuki E Hara K 《Journal of the American Chemical Society》2006,128(44):14256-14257
We designed and synthesized new alkyl-functionalized organic dyes, MK-1 and MK-2, for dye-sensitized solar cells (DSSCs). Based on the MK-2 dye, a high performance of efficiency (eta, 7.7%; short-circuit current density Jsc = 14.0 mA cm-2, open-circuit voltage Voc = 0.74 V, and fill factor FF = 0.74) was achieved under AM 1.5 G irradiation (100 mW cm-2). Remarkably, the relatively higher Voc for DSSCs based on MK-1 and MK-2 dyes, which have long alkyl chains, were observed among the organic dyes caused by the increasing of the electron lifetime in the conduction band of TiO2. Our molecular design of alkyl-functionalized dyes strongly suggests the promising performance of molecular photovoltaics based on organic dyes. 相似文献
179.
In order to investigate the HD isotope effect on a dihydrogen bonded cation system, we have studied NH+4...BeH2 and its isotopomers by ab initio path integral molecular dynamics. It is found that the dihydrogen bond can be exchanged by NH+(4) rotation. The deuterated isotopomer (ND+(4)...BeD(2); DD) can exchange the dihydrogen bond more easily than other isotopomers such as (NH+4...BeH2; HH). This unusual isotope effect is ascribed to the "quantum localization" which occurs when the effective energy barrier for the rotational mode becomes higher by the zero point energy of other modes. We also found that the binding energy of dihydrogen bonds for DD species is the smallest among the isotopomers. 相似文献
180.
Uchiyama S Matsushima E Tokunaga H Otsubo Y Ando M 《Journal of chromatography. A》2006,1116(1-2):165-171
A new method is described for the determination of orthophthalaldehyde in air which is used for the disinfection of various instruments (e.g. endoscopes) in hospital. Orthophthalaldehyde in air was collected with a silica gel cartridge impregnated with acidified 2,4-dinitrophenylhydrazine (DNPH-cartridge) and derivatives were analyzed by high-performance liquid chromatography (HPLC). In this study, the derivatization was examined by comparing the process with three phthalaldehyde isomers (ortho-, iso- and tere-). In the case of iso- and tere-phthalaldehyde, derivatives synthesized with excess of aldehyde consisted mainly of mono-derivatives, and derivatives synthesized with excess of DNPH consisted mainly of bis-derivative. In the case of orthophthalaldehyde, derivative consisted of only bis-derivative and mono-derivative was never observed under any conditions. Orthophthalaldehyde was completely retained by the DNPH-cartridge during air sampling, however, the derivatization reaction was incomplete and unreacted orthophthalaldehyde was flushed from the cartridge during the subsequent solvent extraction process. Unreacted orthophthalaldehyde and DNPH reacted again in the extraction solvent solution. Immediately after the solvent extraction, both mono- and bis-DNPhydrazone derivatives of orthophthalaldehyde were present in the solution. However, over time, the mono-derivative decreased and bis-derivative increased until only the bis-derivative was left allowing accurate determination of the orthophthalaldehyde concentration. The transformation of mono-derivative to bis-derivative was faster in polar aprotic solvents such as acetonitrile, dimethyl sulfoxide and ethyl acetate. Transformation was found to occur most quickly in acetonitrile solvent and was completed in 4 h in this case. It was possible to measure orthophthalaldehyde in air as bis-derivative using a DNPH impregnated silica cartridge and HPLC analysis. 相似文献