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101.
Ilko K. Ilev Hiroshi Kumagai Koichi Toyoda Deepak Uttamchandani Brian Culshaw 《Optical Review》1997,4(1):A58-A60
An alternative and simple fiber-optic backreflectance sensor method for accurate measurement of either effective focal lengths
of optical elements and short distances using a single-mode optical fiber and cw laser is presented. The method is based on
the intensity sensing of focused backreflectance laser emission and the spatial location of three specific points: the focal
point of the focusing optical element and two object points. The single-mode fiber is a key optical element and serves simultaneously
as a point laser source for testing, an object for projecting and a highly sensitive point receiver of the focused backreflectance
emission. The experimental and analytical results demonstrate the potential of the method for locating the spatial points
and determining the effective focal length with accuracies exceeding 1 μm and 0.5%, respectively, as well as for short distance
measurement with submicron accuracy. 相似文献
102.
103.
104.
[reaction: see text] The direct catalytic enantio- and diastereoselective aldol reaction with 2-hydroxy-2'-methoxyacetophenone proceeded smoothly using as little as 1 mol % of a dinuclear zinc catalyst, Zn-Zn-linked-BINOL complex 2, to afford alpha,beta-dihydroxy ketones in a highly syn-selective manner (up to syn/anti 97/3) and in excellent yields (up to 95%) and ees (up to 99%). Efficient transformations of the alpha,beta-dihydroxy ketone into an alpha,beta-dihydroxy ester and an alpha,beta-dihydroxy amide via regioselective rearrangements are also described. 相似文献
105.
Naoaki Kumagai Nobuko Kumagai K. Tanno 《Applied Physics A: Materials Science & Processing》1989,49(1):83-89
The electrochemical characteristics and structural changes associated with discharge and charge of several tungstic acids such as H2WO4 and H2WO4 · H2O have been investigated. The suitability of these substances as new cathode materials for nonaqueous lithium batteries has been assessed. H2WO4, having only coordinated water molecules, showed a discharge capacity of about 410 Ah kg–1 of acid weight and a discharge potential around 2 V vs. Li/Li+. This capacity was much higher than the 40 180 Ah kg–1 of anhydrous WO3. H2WO4 showed a good charge-discharge cycling behavior at a capacity below 1e
–/W. However, the formation of a stable phase such as Li2WO4 during the cyclings limited the cycling number. In addition, the crystal structure of H2WO4 changed from orthorhombic to tetragonal during discharge, but the original layered lattice was kept on discharge to 1.5e
–/W. On the other hand, a significant decrease in the layer spacing of H2WO4 · H2O took place with discharge, due to the direct interaction between the interlayer water molecule and the lithium inserted between the layers. In this paper, in particular, the effect of the coordinated and hydrated water molecules in the acid structure on the electrochemical behavior is discussed. 相似文献
106.
T. Kambara R. Schuch Y. Awaya T. Mizogawa H. Kumagai Y. Kanai H. Shibata K. Shima 《Zeitschrift für Physik D Atoms, Molecules and Clusters》1992,22(2):451-456
We have measured the target thickness dependence ofK-vacancy production probabilities and total cross sections for 40.6 MeV Ar ions hitting Ca and Cu targets. The probabilities were measured as a function of the scattering angle between 0.13° and 1.4° by means of aK x-ray-particle coincidence. By integrating the measured probabilities over the impact parameter a significantly lower total cross section was obtained than the directly measured value. The maximum seen in the impact parameter dependent probability varies with decreasing target thickness towards the results obtained with molecular and atomic gas targets. From these observations a multiple collisionL-vacancy process prior to 2pπ-2pσ rational coupling is concluded. 相似文献
107.
108.
Interaction of heptakis (2,3,6-tri-O-methyl)-beta-cyclodextrin with cholesterol in aqueous solution 总被引:1,自引:0,他引:1
Nishijo J Moriyama S Shiota S Kamigauchi M Sugiura M 《Chemical & pharmaceutical bulletin》2004,52(12):1405-1410
The interaction of cholesterol with heptakis (2,3,6-tri-O-methyl)-beta-cyclodextrin (TOM-beta-CyD) was investigated in water using solubility method. It was found that TOM-beta-CyD forms two kinds of soluble complexes, with molar ratios of 1:1 and 1:2 (cholesterol:TOM-beta-CyD). The thermodynamic parameters for 1:1 and 1:2 complex formation of cholesterol with TOM-beta-CyD were: DeltaG0(1:1)=-11.0 kJ/mol at 25 degrees C (K1:1=7.70 x 10 M(-1)); DeltaH0(1:1)=-1.28 kJ/mol; TDeltaS0(1:1)=9.48 kJ/mol; DeltaG0(1:2)=-27.8 kJ/mol at 25 degrees C (K1:2)=7.55 x 10(4) M(-1)); DeltaH0(1:2)=-0.57 kJ/mol; TDeltaS0(1:1)=27.3 kJ/mol. The formation of the 1:2 complex occurred much more easily than that of the 1:1 complex. The driving force for 1:1 and 1:2 complex formation was suggested to be exclusively hydrophobic interaction. Based on the measurements of proton nuclear magnetic resonance spectra and studies with Corey-Pauling-Koltun atomic models, the probable structures of the 1:2 complex were estimated. In addition, the interaction of TOM-beta-CyD with cholesterol was compared with that of heptakis (2,6-di-O-methyl)-beta-CyD (DOM-beta-CyD). The interaction of TOM-beta-CyD is more hydrophobic than that of DOM-beta-CyD, and the life time of the complexed TOM-beta-CyD is sufficiently long to give separated signals, at the NMR time scale, which differs from that of complexed DOM-beta-CyD. 相似文献
109.
110.
Miyoko Kamigauchi Kinuko Iwasa Narao Takao Toshimasa Ishida Masatoshi Inoue 《Helvetica chimica acta》1987,70(6):1482-1486
The crystal structure of corycavine, a protopine-type alkaloid, has been determined by X-ray analysis. A conformational feature observed is the existence of a strong electrostade interaction between the N- and C-atom at a distance of 2.618 Å. Such an interaction stabilizes the 10-membered ring conformation of the structure. Analyses of NMR spectra indicate that corycavine has the same conformation in solution as in the crystal state. 相似文献