The dehydrogenation kinetics and reversibility improvements of Mg(BH4)2 doped with Ti nano-particles under mild conditions

Magnesium borohydride, Mg(BH₄)₂, is ball-milled with Ti nano-particles. Such catalyzed Mg(BH₄)₂ releases more hydrogen than pristine Mg(BH₄)₂ does during isothermal dehydrogenation at 270, 280, and 290 °C. The catalyzed Mg(BH₄)₂ also exhibits better dehydrogenation kinetics than the pristine Mg(BH₄)₂. Based on kinetics model fitting, the activation energy (E_a) of the catalyzed Mg(BH₄)₂ is calculated to be lower than pristine Mg(BH₄)₂. During partial dehydrogenation, the catalyzed Mg(BH₄)₂ releases 4.23 wt % (wt%) H₂ for the second dehydrogenation at 270 °C, comparing to 4.05, and 3.75 wt% H₂ at 280, and 290 °C. The reversibility of 4.23 wt% capacity is also one of the highest for Mg(BH₄)₂ dehydrogenation under mild conditions such as 270 °C as reported. 4 cycles of Mg(BH₄)₂ dehydrogenation are conducted at 270 °C. The capacities degrade during 4 cycles and tend to be stable at about 3.0 wt% for the last two cycles. By analyzing the hydrogen de/absorption products of the catalyzed sample, Mg(BH₄)₂ is found to be regenerated after rehydrogenation according to Fourier Transform Infrared (FTIR) spectroscopy. Ti nano-particles can react with Mg(BH₄)₂ during ball-milling and de/rehydrogenation. The products include TiH_1.924, TiB, and TiB₂, which can improve the dehydrogenation properties of Mg(BH₄)₂ from a multiple aspect.     

Method for Analyzing Copula-Based Water Shortage Risk in Multisource Water Supply Cities

Water Resources Management - Based on the data series location water, Yellow River water, and the South-to-North Water Diversion water which were obtained from 1985 to 2017 in Zhengzhou, China, a...     

一种远程控制智能防坠楼窗户设计

针对传统窗户和现有的智能窗户进行分析,设计了一种远程控制智能防坠楼窗户,包括基本窗体、电动控制中心、电磁锁、压力传感器、雨滴传感器、烟雾传感器、温湿度传感器等作为系统的信号收集与处理源.电动控制中心通过电机控制窗户左右平移开合,电机作用使窗户停止;通过压力传感器和电磁锁的控制使安全防护网张开;结合App控制窗户开合及环境信息反馈;按下紧急按钮有警示灯光并自动报警.这些对于高空防坠楼、提高生活品质等都有重要意义.     

Study on the flow features of lead-lithium MHD splitting flows under an external magnetic field with arbitrary orientation

Journal of Mechanical Science and Technology - The understanding of magnetohydrodynamic phenomena associated with the flow of electrically-conducting fluid in complex ducts is important and...     

In vitro potential of flavonoids from tartary buckwheat on antioxidants activity and starch digestibility

The effects of various flavonoids of Tartary buckwheat (rutin-enhanced flavonoid extract [REFE and quercetin-enhanced flavonoid extract [QEFE]) and individual flavonoids (rutin, quercetin and kaempferol) on the antioxidant activity, inhibition of α-glucosidases and α-amylase and starch digestibility were evaluated. Quercetin possessed the highest antioxidant activity and inhibition of α-glucosidases and α-amylase activity followed by kaempferol and rutin. REFE and QEFE have similar antioxidant and inhibition of α-amylase activities, but QEFE has much higher α-glucosidases inhibition than REFE. Tartary buckwheat flour has the lowest content of rapidly digestible starch and predicted glycaemic index (pGI) compared to maize flour, wheat flour and rice flour. Addition of rutin and quercetin to wheat flour showed a weak or no effect on digestion inhibition, but they inhibited starch digestion under solid complex conditions. Our results may help explain the benefits of supplementing the diet with food rich in flavonoids.     

Low-temperature synthesis of CdCu3Ti4O12 powders with high dielectric permittivities

The molten salt method was adopted in this work to synthesize CdCu₃Ti₄O₁₂ precursor powders and was found capable of notably reducing the sintering temperature. It was also found that the grain size gradually increases and the grain shape changes from spherical to cubic with increasing proportions of molten salt. The optimal sintering conditions were found to be at approximately 730?°C with the addition of 20% molten salt. After further sintering at 975?°C, the obtained perovskite ceramics exhibited a high dielectric constant at low frequencies.