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111.
《中国化学会会志》2017,64(9):1041-1047
Activated carbons with a high mesoporous structure were prepared by a one‐stage KOH activation process without the assistance of templates and further used as adsorbents for CO2 capture. The physical and chemical properties as well as the pore structures of the resulting mesoporous carbons were characterized by N2 adsorption isotherms, scanning electron microscopy (SEM ), X‐ray diffraction (XRD ), Raman spectroscopy, and Fourier transform infrared (FTIR ) spectroscopy. The activated carbon showed greater specific surface area and mesopore volume as the activation temperature was increased up to 600°C, showing a uniform pore structure, great surface area (up to ~815 m2/g), and high mesopore ratio (~55%). The activated sample exhibited competitive CO2 adsorption capacities at 1 atm pressure, reaching 2.29 and 3.4 mmol/g at 25 and 0°C, respectively. This study highlights the potential of well‐designed mesoporous carbon as an adsorbent for CO2 removal and widespread gas adsorption applications. 相似文献
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Femtosecond optical pulse is used to generate narrow-band terahertz pulses depending on a quasi-phase-matched condition in periodically poled lithium niobate (PPLN) and stoichiometric lithium tantalate (PPSLT) crystals by difference frequency generation. The origin of narrow-band THz generation proved that the two frequency components of the fs pulse contribute to the frequency mixing. By cryogenic cooling, the absorption of THz waves in the crystal is significantly reduced which results in efficient THz generation. Simultaneously generated forward and backward THz pulses were 1.38 and 0.65 THz with as narrow as the bandwidth of 32 GHz in the PPSLT sample. Temperature dependence of the generated THz waveforms had good agreement with the simulation result using one dimensional plane-wave propagation model. 相似文献
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为解决基于雷达高度表探测的地形匹配导航系统探测精度不高、易受电子干扰影响而失效、且在跨海飞行时无法导航的难题,设计了一种激光高度计来代替雷达高度表进行地形探测。采用二极管泵浦固体激光器技术设计激光发射装置,输出近红外/蓝绿双波长激光,既可以测量陆地地形高度,又可以穿透海水探测海底地形;并根据激光高度计拟达到的性能指标选择合适的光电探测器,优化设计了光学系统、扫描系统和信号处理系统。所设计的激光高度计具有体积小、重量轻、高重频、探测灵敏度高、抗电磁干扰能力强等特点。 相似文献
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Lin J Griffin RG Khaneja N 《Journal of magnetic resonance (San Diego, Calif. : 1997)》2011,212(2):402-411
The paper describes two-dimensional solid state NMR experiments that use powdered dephased antiphase coherence (γ preparation) to encode chemical shifts in the indirect dimension. Both components of this chemical shift encoded gamma-prepared states can be refocused into inphase coherence by a recoupling element. This helps to achieve sensitivity enhancement in 2D NMR experiments by quadrature detection. The powder dependence of the gamma-prepared states allows for manipulating them by suitable insertion of delays in the recoupling periods. This helps to design experiments that suppress diagonal peaks in 2D spectra, leading to improved resolution. We describe some new phase modulated heteronuclear and homonuclear recoupling pulse sequences that simplify the implementation of the described experiments based on γ prepared states. Recoupling in the heteronuclear spin system is achieved by matching the difference in the amplitude of the sine/cosine modulated phase on the two rf-channels to the spinning frequency while maintaining the same power on the two rf-channels. 相似文献
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Shape verification aimed for manufacturing process control 总被引:1,自引:0,他引:1