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21.
22.
Makoto Minato Takefumi Kaneko Shogo Masauji Takashi Ito 《Journal of organometallic chemistry》2006,691(11):2483-2488
We describe the synthesis of a new asymmetric P,N,N′-tridentate ligand (bis(pyrid-2-ylethyl) menthylphosphine, BPEMP), containing two pyridyl rings and (1S,2R,5S)-menthylphosphino group. The ligand is obtained in five steps from natural abundant l-menthol. The coordination behavior of the ligand toward cationic (allylic)Pd(II) moiety and its first application in palladium-catalyzed asymmetric allylic alkylation are presented. Crystallographic and spectroscopic analyses reveal that [(η3-allylic)Pd(BPEMP)]+ complex forms only one isomer in the solid state as well as in solution. 相似文献
23.
This paper describes the photochemical surface modification of polystyrene (PS) substrates using vacuum ultraviolet (VUV) light 172 nm in wavelength. We have particularly focused on the effects of atmospheric pressure during VUV irradiation on the obtained surface's wettability and the stability of the wettability, in addition to its chemical structure, morphology, and photooxidation rate. Samples were photoirradiated with VUV light under pressures of 10, 10(3), or 10(5) Pa. Although, in each case, the originally hydrophobic PS surface became highly hydrophilic, the final water-contact angle and photooxidation rate depended on the atmospheric pressure. The samples treated at 10 Pa were less wettable than those prepared at 10(3) and 10(5) Pa due to the shortage of oxygen molecules in the atmosphere. The minimum water-contact angles of the samples treated at 10, 10(3), and 10(5) Pa were about 8 degrees, 0 degrees, and 0 degrees, respectively. With the samples prepared at 10 and 10(3) Pa, photooxidation reactions proceeded in the topmost region closest to the surface, while at 10(5) Pa photooxidation was found to be greatly enhanced in the deeper regions, as evidenced by angle-resolved X-ray photoelectron spectroscopy. Photoetching rates were determined through atomic force microscope observation of microstructured PS samples prepared by a simple mesh-contact method. As estimated from AFM images of the latticed microstructures obtained, the rates of samples prepared at 10(3) and 10(5) Pa were about 1.5 and 1.3 nm/min, respectively. However, no photoetched features were observable on the sample surface prepared at 10 Pa. Hydrophilic stability also varied greatly depending on atmospheric pressure. The hydrophilicity of samples treated at 10 and 10(3) Pa gradually decreased as they were exposed to air. On the other hand, the sample surface prepared at 10(5) Pa showed excellent hydrophilicity even after being left in air for 30 days. 相似文献
24.
Summary The ion exchange selectivity of trivalent metal ions has been determined on titanium antimonate cation exchanger prepared by coprecipitation of antimony to titanium at different mole ratios. The selectivity sequence Al3+<Cr3+<Ga3+<In3+<Fe3+ was found for trivalent metal ions at an initial concentration of 10–4 mol dm–3 in nitric acid media. A high separation factor Ga/Al = KdGa/KdAl, 4.8×103, was observed for the Ga3+–Al3+ pair on titanium antimonate with an antimony to titanium ratio of 0.34. The effective separation of Ga3+ and In3+ from Al3+ was achieved using a 3 cm×0.5 cm i.d. column containing titanium antimonate with an antimony to titanium ratio of 0.34. 相似文献
25.
Mass spectra of ginsenoside-Rg1 deca-acetate 1 Siehe Lit.2. and the related dammaran-type triterpene saponin acetates have been studied and a comment is given on the structure of panaxoside A (=ginsenoside-Rg1) proposed by Elyakov, et al . 相似文献
26.
Kowalczyk P Jaroniec M Kaneko K Terzyk AP Gauden PA 《Langmuir : the ACS journal of surfaces and colloids》2005,21(23):10530-10536
In a previous work, we proposed an improvement of the Derjaguin-Broekhoff-de Boer (DBdB) theory for capillary condensation/evaporation in open-ended cylindrical mesopores. In this paper, we report a further extension of this approach to the capillary condensation/evaporation of nitrogen in siliceous spherical cavities. The main idea of this improvement is to employ the Gibbs-Tolman-Koenig-Buff equation to predict the variation of the surface tension in spherical mesopores. In addition, the statistical film thickness (the so-called t-curve), which is evaluated accurately on the basis of adsorption isotherms measured for MCM-41 materials, is used instead of the originally proposed t-curve to take into account the excess chemical potential due to the surface forces. It is shown that the aforementioned modifications of the original DBdB theory that was refined by Ravikovitch and Neimark have significant implications for the pore size analysis of cagelike mesoporous silicas. To verify the proposed improvement of the DBdB pore size analysis (IDBdB), two series of FDU-1 samples, which are well-defined cagelike mesoporous materials (composed of siliceous spherical cavities interconnected by short necks), were used for the evaluation of the pore size distributions (PSDs). The correlation between the spinodal condensation point in the spherical pores predicted by the nonlocal density functional theory (NDFT) developed by Ravikovitch and Neimark and that predicted by the IDBdB theory is very good in the whole range of mesopores. This feature is mirrored to the realistic PSD characterized by the bimodal structure of pores computed from the IDBdB theory. As in the case of open-ended cylindrical pores, the improvement of the classical DBdB theory preserves its simplicity and simultaneously ensures a significant improvement of the pore size analysis, which is confirmed by the independent estimation of the average pore size by the NDFT and the powder X-ray diffraction method. 相似文献
27.
M Kaneko T Kobayashi H Takano T Ohnishi T Kaku T Nishi C Kawase K Kaneko 《Radioisotopes》1989,38(8):344-346
Thyroid scintigraphy in rats and mice with 99mTc and 123I was attempted to examine whether this modality might be used in small animals and to describe the possibilities of its application in examining experimentally produced thyroid diseases. A human gamma camera with a pinhole collimator improved for small animals was used for imaging. Thyroid images with 99mTc were obtained 20 minutes after injection and those with 123I were 24 hours after administration. All the scintigrams, although those obtained from mice with 99mTc displayed overlapped salivary gland images, demonstrated sufficiently clear images in size and shape, which showed that thyroid scintigraphy in small animals should be applicable in examining experimentally produced thyroid diseases. 相似文献
28.
Kô Kaneko Mikako Tanaka Kimiaki Haruki Nobuaki Naruse Hiroshi Mitsuhashi 《Tetrahedron letters》1979,20(39):3737-3740
The 13C-NMR spectra of seven cavanine alkaloids isolated from Veratrum and Fritillaria plants were measured and their signals were assigned, and these results were applicated for structure elucidation of two new cevanine alkaloids, baimonidine and isoverticine, isolated from mature Fritillaria verticillata. 相似文献
29.
Akiba Y Beavis D Beery P Britt HC Budick B Chasman C Chen Z Chi CY Chu YY Cianciolo V Cole BA Costales JB Crawford HJ Cumming JB Debbe R Engelage J Fung SY Gonin M Gushue S Hamagaki H Hansen O Hayano RS Hayashi S Homma S Kaneko H Kang J Kaufman S Kehoe WL Kurita K Ledoux RJ Levine MJ Miake Y Morrison DP Morse RJ Moskowitz B Nagamiya S Namboodiri MN Nayak TK Olness J Parsons CG Remsberg LP Roehrich D Rothschild P Sakurai H Sangster TC Seto R Soltz R Stankus P Steadman SG Stephans GS Sung T 《Physical review letters》1996,76(12):2021-2024
30.
Asymmetric monobenzoylation reactions of cyclic meso-1,3- and 1,4-diols were catalyzed by a phosphinite derivative of quinidine to afford the corresponding monobenzoylated diol with good yield and enantioselectivity. [reaction: see text] 相似文献