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991.
Tai-ran Wang Jian-cong Li Wu Shu Su-lei Hu Run-hai Ouyang Wei-xue Li 《化学物理学报(中文版)》2020,33(6):703-711
Over the last few years, machine learning is gradually becoming an essential approach for the investigation of heterogeneous catalysis. As one of the important catalysts, binary alloys have attracted extensive attention for the screening of bifunctional catalysts. Here we present a holistic framework for machine learning approach to rapidly predict adsorption energies on the surfaces of metals and binary alloys. We evaluate different machine-learning methods to understand their applicability to the problem and combine a tree-ensemble method with a compressed-sensing method to construct decision trees for about 60000 adsorption data. Compared to linear scaling relations, our approach enables to make more accurate predictions lowering predictive root-mean-square error by a factor of two and more general to predict adsorption energies of various adsorbates on thousands of binary alloys surfaces, thus paving the way for the discovery of novel bimetallic catalysts. 相似文献
992.
Xuemin Ye Beibei Ye Jiahui Xu Mei Fang Danqi Dong Congcong Wu Xupin Lin Yehui Hu Xiaoji Cao Weimin Mo 《Journal of separation science》2020,43(17):3546-3554
In this work, a novel quick, easy, cheap, effective, rugged, and safe technique with hydrophobic natural deep eutectic solvent as both extractant and analyte protectant was developed and combined with gas chromatography–tandem mass spectrometry to analyze pyrethroid residues in tomatoes. Eight hydrophobic natural deep eutectic solvents were first evaluated as analyte protectants and those with decanoic acid or lactic acid as hydrogen bond donor were demonstrated to be effective in compensating for the matrix effects of pyrethroids in the gas chromatography system. Hence, they were added to solvent standards for correcting the quantitation errors instead of matrix‐matched calibration standards. Then the abilities of these acid‐based deep eutectic solvents to extract pyrethriods from tomatoes were evaluated. Results showed the recoveries of all pyrethroids reached to over 80% with only 5 mL menthol:decanoic acid (1:1) used, and good phase separation was easily achieved without the addition of inorganic salt in the extraction step, indicating hydrophobic natural deep eutectic solvent could be a green substitute for acetonitrile in the quick, easy, cheap, effective, rugged, and safe extraction. Compared with the conventional method, the proposed protocol improved the recoveries, reduced the matrix effects, and simplified the extraction step, demonstrating to be an effective, fast, and green method. 相似文献
993.
Chen Wu-Hua Xiong Jin-Hua Teng Xue Mi Jin-Xiao Hu Zhi-Biao Wang Haifeng Chen Zuofeng 《中国科学:化学(英文版)》2020,63(12):1825-1836
Science China Chemistry - A novel CoII-Fenton-like heterogeneous catalyst, (H3O)2[CoII(phen)(H2O)2]2[MoVI5O15(PO4)2]·4H2O (phen=1,10-phenanthroline, C12N2H8) (1), is synthesized and utilized... 相似文献
994.
Coupled Electrical Conduction in Coordination Polymers: From Electrons/Ions to Mixed Charge Carriers
The coupled transport of ions and electrons is of great potential for next‐generation sensors, energy storage and conversion devices, optoelectronics, etc. Coordination polymers (CPs) intrinsically have both transport pathways for electrons and ions, however, the practical conductivities are usually low. In recent years, significant advances have been made in electronic or ionic conductive coordination polymers, which also results in progress in mixed ionic‐electronic conductive coordination polymers. Here we start from electronic and ionic conductive CPs to mixed ionic‐electronic conductive CPs. Recent advances in the design of mixed ionic‐electronic conductive CPs are summarized. In addition, devices based on mixed conduction are selected. 相似文献
995.
自1998年发现宇宙的加速膨胀以来,大量的天文观测显示宇宙中存在压强为负的暗能量成分.暗能量已经成为目前宇宙学和理论物理的最重要的研究课题之一.文章介绍了暗能量存在的天文观测证据和理论研究现状与展望. 相似文献
996.
P doped ZnO films were grown on quartz by radio frequency-magnetron sputtering method using a ZnO target mixed with 1.5 at% P2O5 in the atmosphere of Ar and O2 mixing gas. The as-grown P doped ZnO film showed n-type conductivity, which was converted to p-type after 800 °C annealing in Ar gas. The P doped ZnO has a resistivity of 20.5 Ω cm (p∼2.0×1017 cm−3) and a Hall mobility of 2.1 cm2 V−1 s−1. XRD measurement indicated that both the as-grown and the annealed P doped ZnO films had a preferred (0 0 2) orientation. XPS study agreed with the model that the PZn-2VZn acceptor complex was responsible for the p-type conductivity as found in the annealed P-doped ZnO. Temperature-dependent photoluminescence (PL) spectrum showed that the dominant band is located at 3.312 eV, which was attributed to the free electronic radiative transition to neutral acceptor level (FA) in ZnO. The PZn-2VZn acceptor complex level was estimated to be at EV=122 meV. 相似文献
997.
Lihui SunJifan Hu Feng GaoYongjia Zhang Hongwei Qin 《Physica B: Condensed Matter》2011,406(21):4105-4108
The adsorption of NO molecule on the LaFeO3 (0 1 0) surface was studied using first-principle calculations based on density functional theory. The calculated results indicate that the Fe-top site is the most favorable for NO adsorption. The N-O bond length, Mulliken charge, and the N-O vibration frequency of the NO molecule are discussed after adsorption. The analysis results of the density of the states show that when NO is adsorbed with the Fe-NO configuration, the bonding mechanism is mainly from the interaction between the NO and the Fe d orbit. 相似文献
998.
Hu Jianjun Duan Yuping Zhang JiaJing Hui Liu ShunhuaLi Weiping 《Physica B: Condensed Matter》2011,406(10):1950-1955
MnO2/doped polyaniline (PANI) is prepared by an in situ polymerization method using γ-MnO2 as the addition agent and hydrochloric acid as the doping agent. Products are characterized by FT-IR, UV-vis, XRD, and TEM. Conductivity, electromagnetic properties, and microwave absorption properties are first discussed on the basis of structural characterization. The as-prepared products of MnO2/PANI are partially crystalline in nature and spherical in pattern with grain sizes of 50-70 nm. MnO2 particles are successfully decorated with doped PANI. MnO2/PANI displays moderate electric conduction, excellent dielectric losses, and microwave absorption capabilities. Compared to pure MnO2, the dielectric and reflection loss properties of MnO2/PANI composites exhibit significant improvements, with an effective absorption band at 5 GHz under −10 dB and maximum reflection loss of −21 dB at 13.56 GHz. Pure MnO2 shows an effective absorption band of 3 GHz under −10 dB and a maximum reflection loss of −14.20 dB at 11.5 GHz. Thus, MnO2/PANI composites are found to be a promising microwave absorption material. 相似文献
999.
Guomin Hua Lide Zhang Jun Dai Linhua Hu Songyuan Dai 《Applied Physics A: Materials Science & Processing》2011,102(2):275-280
A facile synthesis route is presented to achieve dimension-tunable ZnO nanostructures by the design of zinc hydroxide precursors
under the surfactant-free condition. From three types of zinc hydroxide precursors, namely, crystalline Zn(OH)(NO3)(H2O) nanobelts, amorphous zinc hydroxides microparticles and soluble Zn(OH)2-4\mathrm{Zn}(\mathrm{OH})^{2-}_{4} species, the porous ZnO nanosheets, ZnO nanoparticles and ZnO nanowires can be achieved, respectively. The porous ZnO nanosheets
exhibit large polar surface area. Thermal analysis indicates that the crystalline Zn(OH)(NO3)(H2O) nanobelts were converted to the porous ZnO nanosheets by in situ lattice reconstruction, which was attributed to the unique fibrous structure of Zn(OH)(NO3)(H2O) nanobelts. The as-prepared dimension-tunable ZnO nanostructures have potential applications in solar cells, photocatalysis,
novel chemical and biological sensors, etc. 相似文献
1000.
Q. Ma Y.-g. Zhang C. Xie W.-d. Shen M.-l. Hu S.-n. Zhang Y.-j. Song Y.-h. Li Q.-y. Wang X. Liu 《Applied physics. B, Lasers and optics》2011,105(2):277-284
A Gires?CTournois interferometer (GTI) with large dispersion compensation was designed and fabricated according to the requirement of the Yb-doped photonic crystal fiber laser system. The designed GTI can provide an average group delay dispersion (GDD) of ?1500 fs2 and a high reflectance (>99.7%) from 1030 to 1050 nm. The Ion-assisted Deposition (IAD) technique was utilized to manufacture the mirror. Good agreement between the measured and designed results both for reflectance and GDD was achieved. The reflectance during 1030?C1050 nm was above 99.5% and the GDD ripple was less than ±300 fs2. The GTI was used both in the intracavity dispersion compensation and extracavity pulse compression for the Yb-doped photonic crystal fiber laser system. A mode-locked soliton pulse with a 506-fs duration was recorded. An extracavity pulse compression test showed that the GTI had identical pulse compression capability as the conventional grating pairs while the energy loss was obviously reduced. Our results demonstrated that the HDM, which was able to provide quite a large amount of negative dispersion (???8×104 fs2), could be an ideal alternative to replace the dispersive compensating grating pairs for the dispersion compensation of the Yb-doped photonic crystal fiber laser system. 相似文献