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排序方式: 共有46条查询结果,搜索用时 15 毫秒
1.
Kabir-ud-Din P. Ajmal Koya Ziya Ahmad Khan 《Journal of Dispersion Science and Technology》2013,34(4):558-567
Effects of three organic solvents, viz. methyl cellosolve, acetonitrile, and formamide, on the micellization process of Gemini surfactant pentamethylene-1,5-bis(tetradecyldimethylammonium bromide) aqueous solutions, with the volume percentages of the organic solvents up to 50%, have been investigated conductometrically. The studies were made at different temperatures and the data were used to find out different micellization parameters. From the study, it was observed that, although an increment in the amount of the organic solvents delays the micellization, the increase in the critical micelle concentration (cmc) is comparatively less below 20%(v/v) showing the predominance of water character in the bulk phase at lower compositions of the organic solvents. Applying equilibrium model for micelle formation, various thermodynamic parameters were also calculated from the temperature dependence of the cmc values and the results show that the micellization process becomes less spontaneous as the volume % of the organic solvent increases in the system due to the action of water-organic solvent mixed media as better solvent than pure water (solvophobic effect) for the studied Gemini molecules. 相似文献
2.
Abe K Abe K Abe T Adam I Akimoto H Aston D Baird KG Baltay C Band HR Barklow TL Bauer JM Bellodi G Berger R Blaylock G Bogart JR Bower GR Brau JE Breidenbach M Bugg WM Burke D Burnett TH Burrows PN Calcaterra A Cassell R Chou A Cohn HO Coller JA Convery MR Cook V Cowan RF Crawford G Damerell CJ Daoudi M de Groot N de Sangro R Dong DN Doser M Dubois R Erofeeva I Eschenburg V Fahey S Falciai D Fernandez JP Flood K Frey R Hart EL Hasuko K Hertzbach SS Huffer ME Huynh X Iwasaki M Jackson DJ 《Physical review letters》2003,90(14):141804
We present an improved direct measurement of the parity-violation parameter A(b) in the Z boson-b-quark coupling using a self-calibrating track-charge technique applied to a sample enriched in Z-->bb events via the topological reconstruction of the B hadron mass. Manipulation of the Stanford Linear Collider electron-beam polarization permits the measurement of A(b) to be made independently of other Z-pole coupling parameters. From the 1996-1998 sample of 400,000 hadronic Z decays, produced with an average beam polarization of 73.4%, we find A(b)=0.906+/-0.022(stat)+/-0.023(syst). 相似文献
3.
Yamaguchi K Ueki R Nonaka H Sugihara F Matsuda T Sando S 《Journal of the American Chemical Society》2011,133(36):14208-14211
Monoamine oxidase (MAO) A is a flavoenzyme that catalyzes the oxidation of biologically important monoamines and is thought to be associated with psychiatric disorders. Here, we report a strategy for rationally designing a (19)F magnetic resonance imaging probe for the specific detection of human MAO-A (hMAO-A) activity. Our designed (19)F probe was oxidized expeditiously by hMAO-A to produce 2-fluoro-4-nitrophenol via a spontaneous β-elimination mechanism. Concomitant with the structural change of the probe to the product, the (19)F chemical shift changed by 4.2 ppm, which was enough to visualize the probe and enzymatic product separately. Importantly, our probe achieved excellent discrimination of hMAO-A from its isoform hMAO-B. 相似文献
4.
To deal with the radiation from an axially symmetric pillbox resonator embedded in LiNbO3 substrate, an eigenvalue equation is derived from the expression of the finite-element beam propagation method in a cylindrical coordinate system. By solving the eigenvalue equation iteratively, the field distributions and the angular phase constants of the pillbox resonator are evaluated. The iterative scheme of solving the eigenvalue equation is an extension of our previous direct solution method which was described for a lossless case. The results obtained by this method are compared with those obtained analytically, and excellent agreement is found. 相似文献
5.
Koji Inui Tomokazu Urakawa Koya Yamashiro Naofumi Otsuru Makoto Nishihara Yasuyuki Takeshima Sumru Keceli Ryusuke Kakigi 《BMC neuroscience》2010,11(1):80
Background
The detection of any abrupt change in the environment is important to survival. Since memory of preceding sensory conditions is necessary for detecting changes, such a change-detection system relates closely to the memory system. Here we used an auditory change-related N1 subcomponent (change-N1) of event-related brain potentials to investigate cortical mechanisms underlying change detection and echoic memory. 相似文献6.
Kawakita M Sasaki H Arai J Okano F Suehiro K Haino Y Yoshimura M Sato M 《Optics letters》2008,33(7):684-686
In projection-type integral imaging, positional errors in elemental images and elemental lenses affect three-dimensional (3D) image quality. We analyzed the relationships between the geometric distortion in elemental images caused by a projection lens and the spatial distortion in the reconstructed 3D image. As a result, we clarified that 3D images that were reconstructed far from the lens array were largely affected, and that the reconstructed images were significantly distorted in the depth direction at the corners of the displayed images. 相似文献
7.
Koya Sakakibara 《BIT Numerical Mathematics》2016,56(4):1369-1400
This paper presents a stability and error estimate of the dipole simulation method applied to Dirichlet problems in Jordan regions. Specifically, it is proved that the error decays exponentially when the boundary data is analytic, and it decays algebraically when the boundary data is not analytic but belongs to some Sobolev space. Moreover, some numerical results and conjectures are presented. 相似文献
8.
Koya Shibano Shiro Kubuki Kazuhiko Akiyama Zoltán Homonnay Ernő Kuzmann Stjepko Krehula Mira Ristić Tetsuaki Nishida 《Hyperfine Interactions》2014,226(1-3):489-497
Nanoparticles (NPs) of Fe3O4 and γFe2O3 synthesized by hydrothermal reaction were characterized by X-ray diffractometry (XRD), 57Fe-Mössbauer spectroscopy and field emission scanning electron microscopy (FE-SEM). A decrease in concentration of methylene blue (MB) aqueous solution due to bulk Fe0-NP γFe2O3 mixture with the mass ratio of 3:7 was measured by ultraviolet-visible light absorption spectroscopy (UV-Vis). The Mössbauer spectrum of NP Fe3O4 prepared from hydrothermal reaction was composed of two sextets with absorption area (A), isomer shift (δ) and internal magnetic field (H int) of 56.3 %, 0.34±0.03 mm s???1 and 49.0±0.30 T for tetrahedral (T d) FeIII, and 43.7 %, 0.66±0.11 mm s???1 and 44.0±0.71 T for octahedral (O h) FeII?+?III. The FeII/FeIII ratio was determined to be 0.280 for NP Fe3O4, giving ‘x’ of 0.124 in Fe3???xO4. These results show that NP Fe3O4 prepared by hydrothermal reaction was not regular but nonstoichiometric Fe3O4. Consistent results were observed for XRD patterns of NP Fe3???xO4 indicating sharp intense peaks at 2Θ of 30.2, 35.7 and 43.3° with a large linewidth of 0.44°, yielding the crystallite size of 29–37 nm from the Scherrer’s equation. Iso-thermal annealing of NP Fe3???xO4 at 250 °C for 30 min resulted in the precipitation of NP γFe2O3 with δ of 0.33±0.03 mm s???1 and H intof 46.4±0.27 T due to magnetic tetrahedral FeIII. The Debye temperature of NP Fe3???xO4 was respectively estimated to be 267±5.45 K for Fe $^{\mathrm{III}}(T_{\mathrm{d}})$ and 282±7.17 K for Fe $^{\mathrm{II+III}}(O_{\mathrm{h}})$ , both of which were smaller than that obtained for bulk Fe3O4 of 280±4.15 K and 307±5.70 K, indicating that the chemical environment of iron of NPs is less rigid than that of the bulk compounds. A leaching test using methylene blue (MB) and mixture of bulk Fe0-NP γFe2O3 (3:7) showed a remarkable decrease in MB concentration from 1.90 × 10???2 to 9.49 × 10???4 mM for 24 h with the first order rate constant (k MB) of 2.1 × 10???3 min???1. This result verifies that MB decomposing ability is enhanced by using NP γFe2O3 compared with the k MB of 1.1 × 10???4 min???1 previously obtained from the leaching test using MB and bulk mixture of Fe0???γFe2O3 (3:7). 相似文献
9.
R Ueki K Yamaguchi H Nonaka S Sando 《Journal of the American Chemical Society》2012,134(30):12398-12401
Dopamine (DA) is a monoamine neurotransmitter that plays important roles in the brain, and whose levels in the brain are associated with several neurological and psychiatric disorders. Therefore, DA metabolism inhibitors have been used as therapeutic agents. Here, we report a (1)H NMR probe for the in situ analysis of DA metabolism, and its application to DA inhibitor screening. We designed doubly (13)C-labeled DA ((13)C(2)-DA) as the probe. The combination of the (13)C(2)-DA and (1)H-{(13)C-(13)C'} NMR technique allowed the selective and thus in situ monitoring of DA metabolism. Using (13)C(2)-DA, we successfully measured the efficacies of different inhibitors in a tissue sample, allowing us to improve the in situ inhibitory efficacy of the known DA metabolism inhibitor, clorgyline. 相似文献
10.
The effect of the addition of 2-methoxyethanol on the critical micelle concentration (cmc) and on the degree of counterion dissociation (??) of butanediyl-1,4-bis(tetradecyldimethylammonium bromide) gemini surfactant, [C14H29N+(CH3)2?C(CH2)4?CN+(CH3)2C14H29,2Br?] (referred as 14?C4?C14,2Br?), has been studied by varying the compositions of the 2-methoxyethanol + water mixed solvent media (0 to 50?%). To determine various thermodynamic parameters of micellization, on the basis of the mass?Caction model for micelle formation, the experiments were performed at selected compositions of the mixed solvent at four temperatures ranging between 25?°C and 50?°C. Furthermore, the air/bulk surface tensions of the pure and mixed media were determined, and a successful attempt was made to correlate the cohesive energy density described through the Gordon parameter with the values of Gibbs energy of micellization. 相似文献