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141.
Guanshi Qin Tatsuya Yamashita Yusuke Arai Yasutake Ohishi 《Optics Communications》2007,279(2):298-302
We demonstrate a 22 dB all-fiber amplifier at 546 nm using Er3+-doped fluoride fiber by forward upconversion pumping of a 974 nm laser diode. The gain saturation effects and the power conversion efficiency of this amplifier are investigated in detail based on gain characteristics and numerical simulations. 相似文献
142.
In applying Pressure-Sensitive Paint (PSP) to low-speed flow wind tunnel testing, it is important to minimize any measurement
uncertainties. There are various error sources such as camera noise, misalignment of images due to model displacement and
temperature distribution over the model. Among these factors, the effects of temperature distribution change during tests
on pressure measurement accuracies were studied in the present paper. Pressure and temperature distributions over a simplified
car model (1/10 scale Ahmed model) were measured using PSP and Temperature-Sensitive Paint (TSP). Sequential images were acquired
at the same intervals over the entire test period, including for the conditions before and after the tunnel run. As a result,
it was found that the measurement error caused by temperature distribution over the model could be reduced using a single-point
temperature measurement. In addition, by measuring surface temperature distributions on the model using TSP, it was proved
that the most accurate pressure measurement could be made by rationing the wind-off image acquired immediately after shutting
down the tunnel to the wind-on image acquired immediately before shutting down the tunnel. Using the present measurement technique,
complicated pressure fields over the Ahmed model were successfully visualized. 相似文献
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147.
T Suzuki S Miyanari Y Tsubata T Fukushima T Miyashi Y Yamashita K Imaeda T Ishida T Nogami 《The Journal of organic chemistry》2001,66(1):216-224
N,N'-Dicyanonaphthoquinodiimines fused with a pyrazine ring 1 were prepared from the corresponding quinones 4. The new acceptors 1 have a planar pi-system and undergo reversible two-stage 1e-reduction. Quaternization of the pyridyl substituent in 1d-f gave pyridinium derivatives 2d+, 2e+, and R-3+, respectively, which are stronger acceptors that undergo three-stage 1e-reduction. Upon electrochemical reduction of these cations, novel radicals 2d., 2e., and R-3. were generated and isolated as stable solids. The molecular geometries determined by X-ray analysis indicated that these radicals adopt a zwitterionic structure, in which the unpaired electron is located on the quinodiimine unit but not on the pyridyl group. These novel radicals undergo facile and reversible 1e-oxidation as well as two-stage 1e-reduction. The observed amphotericity endows the radicals with electrical conductivities (10(-5) to 10(-9) S cm-1), and these thus represent a new motif for single-component organic semiconductors. 相似文献
148.
The palladium‐catalyzed reaction of acid anhydrides with silacyclobutane gives a mixture of cyclic silyl enol ether, carboxy(propyl)silane, and 3‐(carboxysilyl)ketone. In the presence of N,N‐dicyclohexylcarbodiimido (DCC), the reaction preferentially provides a cyclic silyl enol ether in a good yield. In addition, the palladium‐catalyzed reaction of benzoic acid with silacyclobutane in the presence of two equivalents of DCC also affords a cyclic silyl enol ether in a moderate yield. Copyright © 2001 John Wiley & Sons, Ltd. 相似文献
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150.
Shuji Kodama Atsushi Morikawa Kazuya Nakagomi Atsushi Yamamoto Atsushi Sato Kentaro Suzuki Tomohisa Yamashita Tomoko Kemmei Atsushi Taga 《Electrophoresis》2009,30(2):349-356
Nicotine (NC) and its related compounds (cotinine (CN), nornicotine (NN), anatabine (AT) and anabasine (AB)) were simultaneously enantioseparated by CE using a capillary with amino groups and sulfated β‐CD as a chiral selector. The optimum running conditions were found to be 30 mM acetate buffer (pH 5.0) containing 8% sulfated β‐CD with an applied voltage of +15 kV at 30°C using direct detection at 260 nm. Using a capillary coated with amino groups, the EOF migrates toward the positive pole. However, when sulfated β‐CD was added to the BGE, it was found that the EOF migrated toward the negative pole due to ionic adsorption of sulfated β‐CD to amino groups on the capillary inner wall. All the cationic analytes migrated as anions, suggesting that they formed stable anionic complexes with sulfated β‐CD. With this system and a simple pretreatment with mini‐cartridges, NC alkaloids in five cigarette samples were enantioseparated. As a result, each of the compounds except for CN was detected. In the case of NC, only (S)‐NC was detected (more than 99.9%), but in the case of NN, AT and AB, the ratios of (S)‐isomer to total isomers were in the ranges 58–70, 81–85 and 59–65%, respectively. On the other hand, only NC was detected in cigarette smoke and the ratio of (S)‐ and (R)‐NCs was 96:4. The amounts of NC alkaloids in cigarettes suggest that the production of (R)‐NC resulted from racemization due to the high temperature/burning of the cigarette. 相似文献