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101.
Reduction of Dimerization Tendency Due to the Decrease in Hybridization Index by Inclusion of 4s and 4p Semicore States as Valence States in Mon (n=2-18) Clusters: A First-Principles Study 下载免费PDF全文
Zhao-ye Gong Zhi-qiang Sun Yan-wen Ding Shuai Zhang Zhen-long Lv Xiao-fei Wang Li-ben Li Hai-sheng Li 《化学物理学报(中文版)》2021,34(5):639-648
Owing to the unique structural, electronic, and physico-chemical properties, molybdenum clusters are expected to play an important role in future nanotechnologies. However, their ground states are still under debate. In this study, the crystal structure analysis by particle swarm optimization (CALYPSO) approach is used for the global minimum search, which is followed by first-principles calculations, to detect an obvious dimerization tendency in Mo\begin{document}$ _n $\end{document} (\begin{document}$ n $\end{document} = 2\begin{document}$ - $\end{document} 18) clusters when the 4s and 4p semicore states are not regarded as the valence states. Further, the clusters with even number of atoms are usually magic clusters with high stability. However, after including the 4s and 4p electrons as valence electrons, the dimerization tendency exhibits a drastic reduction because the average hybridization indices \begin{document}$ H_{ \rm{sp}} $\end{document} , \begin{document}$ H_{ \rm{sd}} $\end{document} , and \begin{document}$ H_{ \rm{pd}} $\end{document} are reduced significantly. Overall, this work reports new ground states of Mo\begin{document}$ _n $\end{document} (\begin{document}$ n $\end{document} = 11, 14, 15) clusters and proves that semicore states are essential for Mo\begin{document}$ _n $\end{document} 相似文献
102.
Cheng Fei Xu Yunfei Lv Zhenfei Huang Zhaohui Fang Minghao Liu Yan’gai Wu Xiaowen Min Xin 《Journal of Thermal Analysis and Calorimetry》2021,146(5):2089-2099
Journal of Thermal Analysis and Calorimetry - In this study, we focus on important global issue containing both environmental pollution control and energy saving. High density polyethylene (HDPE)... 相似文献
103.
Zhen-Yu Wang Guang-Qiang Xu Li Zhou Cheng-Dong Lv Ru-Lin Yang Bing-Zhe Dong Qing-Gang Wang 《高分子科学》2021,39(6):709-715
The isoselective ring-opening polymerization of racemic lactide was achieved by combining N-heterocyclic olefin(NHO) with mono(thio)ureas or bis(thio)ureas as catalytic systems. The polymerization process shows high stereoselectivity, controllability and reactivity,delivering multi-block isotactic polylactides with high chain-end fidelity and narrow molecular weight distributions. The enhancement of catalytic performance was observed in the following order: bisthiourea(DTU) monothiourea(TU) bisurea(DU) urea(U). The highest Pm(probability of forming a meso dyad) = 0.91 was observed at-70 °C when using NHO/U1 catalytic system and the high stereoselectivity was attributed to chain-end control mechanism. 相似文献
104.
Cellulose - In this study, a biomass pretreatment strategy with a recyclable cosolvent (toluene sulfonic acid/ethanol) was developed. The low boiling point solvent (78.15 °C),... 相似文献
105.
Mubashir Hussain Zhen Chen Mu Lv Jingyi Xu Xiaohan Dong Jingzhou Zhao Song Li Yan Deng Nongyue He Zhiyang Li Bin Liu 《中国化学快报》2021,31(12):3163-3167
The rapid identification of pathogens is crucial in controlling the food quality and safety. The proposed system for the rapid and label-free identification of pathogens is based on the principle of laser scattering from the bacterial microbes. The clinical prototype consists of three parts: the laser beam, photodetectors, and the data acquisition system. The bacterial testing sample was mixed with 10 mL distilled water and placed inside the machine chamber. When the bacterial microbes pass by the laser beam, the scattering of light occurs due to variation in size, shape, and morphology. Due to this reason, different types of pathogens show their unique light scattering patterns. The photo-detectors were arranged at the surroundings of the sample at different angles to collect the scattered light. The photodetectors convert the scattered light intensity into a voltage waveform. The waveform features were acquired by using the power spectral characteristics, and the dimensionality of extracted features was reduced by applying minimal-redundancy-maximal-relevance criterion (mRMR). A support vector machine (SVM) classifier was developed by training the selected power spectral features for the classification of three different bacterial microbes. The resulting average identification accuracies of E. faecalis,E. coli and S. aureus were 99%, 87%, and 94%, respectively. The overall experimental results yield a higher accuracy of 93.6%, indicating that the proposed device has the potential for label-free identification of pathogens with simplicity, rapidity, and cost-effectiveness. 相似文献
106.
107.
Development of Two‐Channel Phosphorescent Core–Shell Nanoprobe for Ratiometric and Time‐Resolved Luminescence Imaging of Intracellular Oxygen Levels 下载免费PDF全文
108.
采用溶胶凝胶法与等体积浸渍相结合制备了一系列以粘土为载体的K-Co-Mo催化剂. 采用XRD、N2等温吸脱附、H26+的还原,但对Mo4+和Co2+的还原没有明显的影响. 催化剂经还原后,在其表面生成了一种更低价态的Moδ+(1<δ<4)物种,被认为是合成醇的活性中心. 与非负载催化剂相比,粘土担载的K-Co-Mo具有更高的合成醇性能. 负载型催化剂具有较高的活性物种分散度,并且其介孔结构在一定程度上延长了合成醇反应中间体的滞留时间,从而促进了低碳醇的生成. 经773 K还原的催化剂具有较高的活性,其原因可为催化剂表面具有较高含量的Moδ+物种. 相似文献
109.
Qing Wang Bo Liu Yangyang Xia Yonghui Zheng Ruru Huo Min Zhu Sannian Song Shilong Lv Yan Cheng Zhitang Song Songlin Feng 《固体物理学:研究快报》2015,9(8):470-474
Phase‐change memory (PCM) is regarded as one of the most promising candidates for the next‐generation nonvolatile memory. Its storage medium, phase‐change material, has attracted continuous exploration. Along the traditional GeTe–Sb2Te3 tie line, the binary compound Sb2Te3 is a high‐speed phase‐change material matrix. However, the low crystallization temperature prevents its practical application in PCM. Here, Cr is doped into Sb2Te3, called Cr–Sb2Te3 (CST), to improve the thermal stability. We find that, with increase of the Cr concentration, grains are obviously refined. However, all the CST films exhibit a single hexagonal phase as Sb2Te3 without phase separation. Also, the Cr helps to inhibit oxidation of Sb atoms. For the selected film CST_10.5, the resistance ratio between amorphous and crystalline states is more than two orders of magnitude; the temperature for 10‐year data retention is 120.8 °C, which indicates better thermal stability than GST and pure Sb2Te3. PCM cells based on CST_10.5 present small threshold current/voltage (4 μA/0.67 V). In addition, the cell can be operated by a low SET/RESET voltage pulse (1.1 V/2.4 V) with 50 ns width. Thus, Cr–Sb2Te3 with suitable composition is a promising novel phase‐change material used for PCM with high speed and good thermal stability performances. (© 2015 WILEY‐VCH Verlag GmbH &Co. KGaA, Weinheim) 相似文献
110.