Hydrogen absorption and desorption kinetics of MgH2 catalyzed by MoS2 and MoO2

The catalytic effect of MoS₂ and MoO₂ on the hydrogen absorption/desorption kinetics of MgH₂ has been investigated. It is shown that MoS₂ has a superior catalytic effect over MoO₂ on improving the hydrogen kinetic properties of MgH₂. DTA results indicated that the desorption temperature decreased from 662.10 K of the pure MgH₂ to 650.07 K of the MgH₂ with MoO₂ and 640.34 K of that with MoS₂. Based on the Kissinger plot, the activation energy of the hydrogen desorption process is estimated to be 101.34 ± 4.32 kJ mol⁻¹ of the MgH₂ with MoO₂ and 87.19 ± 4.48 kJ mol⁻¹ of that with MoS₂, indicating that the dehydriding process energy barrier of MgH₂ can be reduced. The enhancement of the hydriding/dehydriding kinetics of MgH₂ is attributed to the presence of MgS and Mo or MgO and Mo which catalyze the hydrogen absorption/desorption behavior of MgH₂. The detailed comparisons between MoS₂ and MoO₂ suggest that S anion has superior properties than O anion on catalyzing the hydriding/dehydriding kinetics of MgH₂.     

CMIP5气候模式对未来30年太阳辐射变化的预估研究

使用CMIP5中33个全球气候模式的模拟数据,选择中位数集合方案,分别在RCP4.5和RCP8.5情景下对2006～2050年全球所有天气条件下地表接收到的太阳辐射、无云条件下地表接收到的太阳辐射、相对湿度、近地层风速、近地层气温和云量的变化进行预估研究。结果表明:1)在RCP8.5情景下,气温的增温率在50°N以北地区最大,达0.12 K/a。同时北半球增温率大于南半球,陆表气温的增温率大于海表气温;2)在RCP4.5和RCP8.5情景下,中国东南部和欧洲中东部地区的地表太阳直接辐射呈现较大正趋势;3)在所选3个区域中,不同RCP情景下地表太阳辐射均呈现正趋势,其中在RCP8.5情景下法国波尔多地表太阳辐射呈现最大正趋势。     

Nonlinear dynamic characteristics and bifurcation analysis of Ti–Zr–Ni quasicrystal as hydrogen storage material

In this article, the nonlinear dynamic characteristics and bifurcation of a Ti–Zr–Ni quasicrystal impacted by hydrogen atoms are studied. New nonlinear damping terms are proposed to express the delay characteristics of Ti–Zr–Ni quasicrystal, and the accurate natural frequency is obtained by the harmonic balance method. A new method based on the developed largest Lyapunov exponent is proposed to analyze the local stability of any point in the system, and the system's global stability is determined. Finally, a new way to realize the switch between hydrogen storage and release based on stochastic Hopf bifurcation is proposed. The results of theoretical analysis and numerical simulation show that the system's motion can be switched between a periodic orbit and a balanced point near the bifurcation boundary with little energy consumption, which is helpful for hydrogen storage and release.     

Enhanced photo-electrochemical activity of ZnO/Cu2S nanotube arrays photocathodes

ZnO/Cu₂S nanotube arrays are fabricated firstly by a facile and capping-agent-free method, and the photo-electrochemical performance has been studied systematically. The results show that ZnO/Cu₂S nanotube arrays achieve enhanced photo-electrochemical water splitting performance and the photocurrent densities of ZnO/Cu₂S are 7.9 times than that of ZnO at 0 V versus Ag/AgCl. The performance of the ZnO/Cu₂S nanotube arrays can be adjusted by changing the amount of Cu₂S microcrystals. The results confirm that the enhanced photo-electrochemical performance of ZnO/Cu₂S is due to the significantly improved visible light absorption, effective separation of photo-induced carriers due to the well band energy match and the formed p-n junction between ZnO and Cu₂S.     

插值算法在内燃机瞬时转速测量中的应用研究

提出了采样信号的插值计算公式 ;考虑到测量信号中调制现象的影响 ,提出了插值法在瞬时转速计算中的误差公式 ;并针对 6 - 135 G柴油机最高转速对两点插值和三点插值的精度进行了计算 ;最后用实测数据进行了验证。结果表明这是提高瞬时转速测量精度的一种有效方法 ,在 5 0 k Hz的低采样率下即可得到较平滑的瞬时转速波形。     

NPT5型空气压缩机机油乳化的原因及对策

针对NPT5型空气压缩机机油乳化的惯性故障,分析了造成机油乳化的主要原因,提出了拆检空气压缩机出风管路逆止阀、检查气阀和活塞、安装自动排水阀和更换机油等预防措施,并提出了重新界定机油含水量标准、加强油质监控和使用添加剂的建议。     

超选择性肾动脉碘油－无水乙醇乳化液栓塞术治疗肾肿瘤

目的探讨肾动脉内碘油－无水乙醇混合物栓塞治疗肾肿瘤的效果。方法收集２０例肾脏恶性肿瘤和良性肿瘤,采用同轴微导管超选择性肾动脉插管,以容积比为２∶１的碘油－无水乙醇乳化液栓塞肾肿瘤供血血管各分支,术后４周复查肾动脉造影,酌情重复治疗,定期随访。结果１８例经一次栓塞肿瘤坏死彻底,栓塞后４周,肿瘤供血中断。其中肾癌及肾转移癌体积减小在５０％以上１３例,占８１．３％,碘油聚集良好;２例重复治疗１次,临床症状明显减轻。结论超选择性肾动脉碘油－无水乙醇乳化液栓塞术,可以在最大限度保护肾功能的前提下,在毛细血管水平栓塞肿瘤所有供血血管,达到永久性栓塞的效果,疗效肯定,值得推广。     

植入式给药装置对比外周静脉穿刺中心静脉置管应用于肿瘤患者长期静脉给药的卫生经济学分析

【摘要】 目的 对植入式给药装置（PORT）和外周静脉穿刺中心静脉置管（PICC）应用于肿瘤患者长期静脉给药的卫生成本和健康产出进行综合分析,阐述PORT相比PICC的卫生经济性。方法 采用回顾性文献研究和肿瘤患者问卷调查,基于社会视角,对PORT和PICC应用于患者长期静脉给药的成本和健康产出进行测算,并将质量调整生命年（QALYs）转换为货币单位,进行成本-效益分析。结果 由于价格差异,肿瘤患者静脉给药初期PORT的费用明显高于PICC,当全面计算各项卫生成本和健康产出时,给药3.9个月时两者净收益将持平,之后PORT的净收益都高于PICC且随着给药时间延长而不断提高。结论 肿瘤患者长期静脉给药中应用PORT的经济性优于应用PICC。

     

太阳能中温闪蒸海水淡化系统产水性能研究

为提高系统产水性能并降低内部结垢,提出一种由非跟踪复合抛物面聚光器加热导热油至100 ℃以上作为供能热源,采用喷雾辅助闪蒸的海水淡化系统。实验研究实际天气中,不同太阳辐照度下进水口温度、进水流量对系统产淡水性能的影响。采用密封压力桶可将进水口温度升至沸点以上,最高可达123 ℃。太阳辐照度波动较大时,进水口温度保持稳定,系统可稳定运行。进水口温度对产水速率影响显著,平均进水口温度从100 ℃升至120 ℃时,产水速率提高47.61%。当进水流量为50 kg/h,压力维持在0.045 MPa时,系统产水速率最大,日累计淡水产量可达11.14 kg/（d·m²）,小时效率为81.45%,单级生产率为9.15%。     

Mechanism of Hg<Superscript>0</Superscript> oxidation in the presence of HCl over a CuCl<Subscript>2</Subscript>-modified SCR catalyst

CuCl₂-SCR catalysts prepared by an improved impregnation method were examined to evaluate the catalytic activity for gaseous elemental mercury (Hg⁰) oxidation in the presence of HCl at the typical SCR reaction temperature of 350 °C. It was found that Hg⁰ oxidation activity of commercial SCR catalyst was significantly improved by the introduction of CuCl₂. The X-ray fluorescence and Hg⁰ temperature-programmed desorption (Hg⁰-TPD) methods were employed to characterize the catalysts. The results indicated that CuCl₂ on CuCl₂-SCR catalyst could release active Cl species in the presence of O₂ at 350 °C, and the released active Cl species could be replenished in the presence of gas-phase HCl. CuCl₂-SCR catalyst possessed the appropriate active sites for the adsorption of NH₃ and HCl, which could scavenge the inhibiting effect of NH₃ on Hg⁰ oxidation. Hg⁰-TPD results suggested that the oxidized mercury compounds mainly exited as HgCl₂ once HCl was present. The Hg⁰ oxidation mechanism over CuCl₂-SCR catalyst in the presence of HCl could be explained as follows: The adsorbed Hg⁰ reacted with active Cl species released by CuCl₂ to form HgCl₂. The reduced CuCl was re-chlorinated to CuCl₂ via the intermediate copper oxychloride (Cu₂OCl₂) formation by being exposed to the gas-phase HCl.