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301.
The BF3-catalyzed reactions of diphenyl-substituted and endo-monophenyl-substituted homobenzoquinone epoxides proceeded through a regioselective oxirane ring opening followed by participation of a pi-aryl transannular cyclization to give the tricyclic diketo alcohols. The conformationally semirigid ethano-bridged diphenyl-substituted homologues also provided similar diketo alcohols and the subsequent ring-expanded cycloheptenedione (via a subsequent 1,2-acyl migration associated with cyclopropane ring opening), depending on the methyl-substitution pattern of the quinone frame. However, the exo-monophenyl-substituted and the rigid biphenyl-2,2'-diyl-substituted homobenzoquinone epoxides essentially remained unchanged. 相似文献
302.
Polydimethylsiloxane‐coated partitioning sample collection device for the precise quantification of polycyclic aromatic hydrocarbons in air 下载免费PDF全文
Ikuo Ueta Moe Onikata Koji Fujimura Tomotaka Yoshimura Shoji Narukami Suguru Mochizuki Tomohiro Sasaki Tsuneaki Maeda 《Journal of separation science》2016,39(21):4202-4208
A novel partitioning collection device comprising a glass cartridge packed with poly(dimethylsiloxane)‐coated macroporous silica particles was developed for the precise quantification of polycyclic aromatic hydrocarbons in air. The analyte collection and elution performances achieved using different amounts of poly(dimethylsiloxane) coating were quantitatively evaluated. The sample retention power increased with increasing the coating, and more than 250 L of air could be collected without analyte breakthrough at a sampling temperature of 35°C. During the air collection, the moisture in the air was not retained on the particles due to the hydrophobic surface of the sorbent. A complete and rapid elution of the collected analytes from the device was accomplished by the passage of only 10 mL of acetone with ultrasonication for 1 min. The proposed method was successfully applied for the determination of airborne polycyclic aromatic hydrocarbons in tunnel air. 相似文献
303.
Kiriyama H Mori M Nakai Y Shimomura T Tanoue M Akutsu A Kondo S Kanazawa S Okada H Motomura T Daido H Kimura T Tajima T 《Optics letters》2008,33(7):645-647
We report a high-contrast, high-intensity Ti:sapphire chirped-pulse amplification system that incorporates a nonlinear preamplifier based on optical parametric chirped-pulse amplification (OPCPA). By cooling the Ti:sapphire crystal in the final amplifier down to 77 K, the chirped-pulses are amplified to 2.9 J at a 10 Hz repetition rate without a thermal lensing effect. Pulse compression down to 19 fs duration obtained after amplification indicates a peak power of 80 TW. With the OPCPA, the temporal contrast is significantly improved to better than 7x10(-9) in a few picoseconds interval prior to the main laser pulse. 相似文献
304.
The design and test results for a capillary pumped loop (CPL) for thermal management of up to 210 W at the source and heat transfer over a distance of 1 m are discussed. The design configuration of the CPL evaporator consists of an internally grooved aluminum evaporator, 31.70-mm outer diameter and 500-mm long, fitted with a porous ultra-high molecular weight polyethylene wick, 8- to 15-μm pore radius, and 38% porous volume. Heat was transferred using a stainless steel tube of 4.5-mm internal diameter for vapor and liquid lines. High-grade acetone (99.99% pure) was used as the heat transfer fluid inside the loop. In the tests, thermal characteristics of the CPL were specifically studied with respect to the temperature control capability using an active thermal device on the reservoir and to the start-up process through pressure priming of the capillary evaporator. The loop was able to start-up successfully at both low and high heat loads, although proper priming of the wick structure before start-up was necessary to attain low evaporator temperatures during steady-state operation. While maintaining constant reservoir temperature through active means, the loop was able to control evaporator temperature within 55 ± 3°C, even with changing input heat from 30 to 210 W. Total thermal resistance from the evaporator surface to the surroundings was 0.19° to 1.15° C/W with the minimum value achieved at the maximum heat load of 210 W. This study is intended to illustrate the thermal potential of the CPL as an effective temperature control device in automotive applications. 相似文献
305.
Takeshi Asai Shichio Kawai Ryo Nagai Shoji Mochizuki 《Journal of Physics and Chemistry of Solids》1984,45(2):173-179
From 1H and 7LiNMR relaxation times T1, T2 and T1ρ in Li5NI2 and the solid solution Li5NI2?0.77LiOH, the diffusive motion of the Li+ ion was studied to make clear the role of the OH? ion in improving the Li+ ionic conduction. At temperatures as low as 140 K, each Li+ ion jumps among four available positions. Its activation energies are 9.26 and 11.8 kJ mol?1 for Li5NI2 and Li5NI2?0.77LiOH, respectively. Diffusive motion was observed in T2 and T1ρ above 240 K. The mode of the cation distribution and the diffusion mechanism are not affected by the presence of the OH? anion. The most noticeable fact is that the OH? ion is substituted selectively for the N3? ion that is the nearest neighbour of the Li+ ion. This selective substitution increases the concentration of the Li+ vacancy most effectively up to 4.2% of the total Li positions. At the same time it diminishes the strong attractive force of the N3? anion binding the Li+ ion to the position, and thus the activation energy. For the diffusion, an anomalously low attempt frequency of 3̃ × 109Hz was obtained from T1ρ, while the normal value of 4.8 × 1012Hz was obtained from the ionic conductivity. The large discrepancy was attributed to the collective nature of the Li+ diffusive motion. 相似文献
306.
Theoretical modelling of miniature loop heat pipe 总被引:1,自引:0,他引:1
Randeep Singh Aliakbar Akbarzadeh Chris Dixon Masataka Mochizuki 《Heat and Mass Transfer》2009,46(2):209-224
Development in the design and thermal performance of the loop heat pipes (LHPs) demands the corresponding improvement in the
theoretical modeling capabilities of these devices. In this paper, mathematical model for assessing the thermal performance
of the miniature LHPs (mLHPs) on the basis of the operating temperature and thermal resistance of the loop has been discussed
in detail. In order to validate the theoretical model, a mLHP with the flat disk shaped evaporator, 30 mm in diameter and
10 mm thick, was developed and tested with nickel and copper wick structure. By comparison with experimental results, it was
found that the theoretical model was able to predict the evaporator temperature and loop thermal resistance very well and
within the uncertainties imposed by the underlying assumptions. The mathematical model can be used to validate the design
of the mLHP and verify whether the proposed design is consistent with the maximum heat load capacity required for the intended
application. In addition to this, the model can assists in understanding and refining the outcomes of the experimental studies. 相似文献