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21.
Anharmonic and harmonic rate constants of the reactions have been calculated with the Rice–Ramsperger–Kassel–Marcus theory, and the anharmonic results are higher than the harmonic ones. The anharmonic effect and isotopic effect on the decomposition reactions have also been examined. The anharmonic effect in all the four reactions is obvious, especially at the high temperatures or energies. Relatively, the anharmonic effect on the reaction trans-acetic acid → TS2 radical is the least obvious among the four reactions. In the microcanonical system, the difference of the rate constants between the deuterated results and the non-deuterated results is not negligible; in other words, the isotopic effect is obvious in all the four reactions. Among these reactions, three of the deuterated results (d, d3 and d4) have a big difference. 相似文献
22.
Dr. Yongguang Li Shanshan Wu Lingling Zhang Xin Xu Yajun Fang Juzhen Yi Dr. Jehan Kim Dr. Bowen Shen Prof. Myongsoo Lee Dr. Liping Huang Liwei Zhang Junhui Bao Prof. Hongbing Ji Prof. Zhegang Huang 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(48):21709-21713
Rapid and selective removal of micropollutants from water is important for the reuse of water resources. Despite hollow frameworks with specific functionalized porous walls for the selective adsorption based on a series of interactions, tailoring a stable shape of nanometer- and micrometer-sized architectures for the removal of specific pollutants remains a challenge. Here, exactly controlled sheets, tubes, and spherical frameworks were presented from the crosslinking of supramolecular colloids in polar solvents. The frameworks strongly depended on the architecture of original supramolecular colloids. As the entropy of colloids increased, the initial laminar framework rolled up into hollow tubules, and then further curled into hollow spheres. These shape-persistent frameworks showed unprecedented selectivity as well as specific recognition for the shape of pollutants, thus contributing to efficient pollutant separation. 相似文献
23.
Dr. Zhenfei Li Dr. Xin Ren Dr. Weichao Tian Dr. Yi Zheng Dr. Jiachen Sun Dr. Liwei An Dr. Lizhi Wen Prof. Li Wang Prof. Guangchuan Liang 《ChemElectroChem》2020,7(9):2174-2183
High tap density and superior electronic conductivity of LiFePO4/KB was synthesized by a combination of wet ball-milling, spray drying, and carbothermal reduction with Ketjen black (KB) as a carbon additive. KB is a conductive carbon black with the special chain-like structure. When KB is used to coat on the surface of primary particles of LiFePO4, the chain-like structure can form a developed 3D network structure between the primary particles of LiFePO4. This special structure can not only provide conductive channels for electrons but also cause the primary particles of LiFePO4 to aggregate tightly. Comparing to the conventional carbon coating materials (only glucose as the carbon source) with a low volumetric energy density of 452.5 Wh L−1 at 1 C rate, we simultaneously increased the electrical conductivity (7.8×10−2 S cm−1) and tap density (1.6 g cm−3) by adding KB, resulting in a higher volumetric energy density of 829.9 Wh L−1 at 1 C rate. When KB is added at 5 % of glucose mass, the LiFePO4/KB composite shows an excellent discharge capacity of 161.6 mAh g−1 at 0.2 C and the 97.7 % retention rate after 500 cycles at 5 C. 相似文献
24.
Dr. Siru Chen Dr. Ming Cui Zehao Yin Qi Zeng Zhenyu Cao Jiabin Xiong Prof. Liwei Mi Yanqiang Li 《ChemElectroChem》2020,7(19):4131-4135
Oxygen reduction reaction (ORR) catalysts with hierarchical pore structures, high specific surface area and multiple heteroatoms doping is very attractive due to the rapid mass transport and abundant active sites. In this work, we reported a facile confined strategy to prepare N, P co-doped hierarchical porous carbon (NPHC) and investigated their catalytic performance for ORR. The strategy greatly simplifies the synthesis procedure of 3D hierarchical carbon templated by SiO2, which can utilize small organic molecules as carbon sources and avoids the pre-polymerization and post-washing process. Moreover, this strategy can be readily extended to synthesis other carbons by simply changing the carbon sources and heteroatom sources, or to synthesize metal compounds/carbon composites by adding metal sources during the synthesis process for energy conversion and storage. 相似文献
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26.
为了优化大化肥中的液氮洗关键流程以提高能量效率、控制CO2排放,在使用Aspen Plus软件对某低温液氮洗工艺进行模拟分析的基础上,结合多目标遗传算法和二次规划法(MOGA-QP)来解决局部极值和大规模优化问题.根据超结构方法,构建了液氮洗工艺流程总结构,即在原流程中加入了一个减压阀和一个分离器,由此可以增补29.546 kJ/kg冷量,使得液氮洗涤塔出口净化气中的CO体积分数为0.55×10-6.利用MOGA-QP求解了超结构,即在进化过程中用二次规划法来模拟流程表单的各个子模块,在最终收敛的环节用二次规划法求解子问题,从而对遗传算法产生的Pareto解做进一步的精细优化.实际应用显示:在满足工艺指标的前提下,优化后的液氮入口流量减至0.131 2 kmol/s,出口CO体积分数降至0.25×10-6,液氮入口流量减少了1.7%,火用损失减少了15.7%,表明改进流程更佳,MOGA-QP算法有效. 相似文献
27.
基于多阈值模糊增强的手指静脉图像分割 总被引：1，自引：0，他引：1
根据手指静脉图像的特点,针对经典阈值方法难以满足图像多属性分割要求的不足,文章在单层次模糊图像增强算法的基础上,提出了一种改进的手指静脉图像分割算法,讨论了该算法的基本原理和具体计算步骤.实验结果表明：与传统的方法相比,该算法方法简单、容易实现,对低质量手指静脉的分割达到了令人满意的效果,分割结果不但准确而且纹路具有明显方向性. 相似文献
28.
For count data, though a zero-inflated model can work perfectly well with an excess of zeroes and the generalized Poisson model can tackle over- or under-dispersion, most models cannot simultaneously deal with both zero-inflated or zero-deflated data and over- or under-dispersion. Ear diseases are important in healthcare, and falls into this kind of count data. This paper introduces a generalized Poisson Hurdle model that work with count data of both too many/few zeroes and a sample variance not equal to the mean. To estimate parameters, we use the generalized method of moments. In addition, the asymptotic normality and efficiency of these estimators are established. Moreover, this model is applied to ear disease using data gained from the New South Wales Health Research Council in 1990. This model performs better than both the generalized Poisson model and the Hurdle model. 相似文献
29.
Lijuan Li Bingdong Li Liwei Feng Xiaoqiu Zhang Yuqian Zhang Qiannan Zhao Guifu Zuo Xianguang Meng 《Molecules (Basel, Switzerland)》2021,26(13)
In this work, Au-modified F-TiO2 is developed as a simple and efficient photocatalyst for H2O2 production under ultraviolet light. The Au/F-TiO2 photocatalyst avoids the necessity of adding fluoride into the reaction medium for enhancing H2O2 synthesis, as in a pure TiO2 reaction system. The F− modification inhibits the H2O2 decomposition through the formation of the ≡Ti–F complex. Au is an active cocatalyst for photocatalytic H2O2 production. We compared the activity of TiO2 with F− modification and without F− modification in the presence of Au, and found that the H2O2 production rate over Au/F-TiO2 reaches four times that of Au/TiO2. In situ electron spin resonance studies have shown that H2O2 is produced by stepwise single-electron oxygen reduction on the Au/F-TiO2 photocatalyst. 相似文献
30.