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991.
仪器分析实验是化学及相关专业的重要实验课程。结合课程特点和培养目标,提出了将比较教学法融入课堂的教学方法,指出了意义和作用,介绍了教学中开展比较教学的实践与应用。该方法加强了学生对仪器功能特点的掌握,激发其实验兴趣和创新精神,学生的认知能力在比较过程中不断建构、丰富、提高和发展,取得了较好的效果。 相似文献
992.
Three 1D/2D HgII coordination polymers (CPs), namely {[Hg3(L)2Cl6](H2O)}n ( 1 ), [Hg(L)Br2]n ( 2 ), and [Hg(L)I2]n ( 3 ) were prepared by assembly of 3,4-bis(3-pyridyl)-5-(4-pyridyl)-1,2,4-triazole (L) with different inorganic HgII salts (i.e. HgCl2, HgBr2 or HgI2). Single-crystal X-ray diffraction analysis reveals two types of bimetallic subunits [(Hg)2C6N4] and [(Hg)2C12N6] in CP 1 , which are further extended to a 2D coordination network. Both of CPs 2 and 3 show 1D zigzag arrays bridged by L ligands. Notably, the L ligands take the (η4, μ4) coordination fashion in 1 but (η2, μ2) binding mode in 2 and 3 . The structural differences of CPs 1 – 3 indicate that the L ligand can adjust its coordination fashions to meet the requirements of HgII centers, relying on the presence of distinct halide anions. In addition, 1 can be applied to fabricate an electrochemical biosensor for the detection of penicillin. 相似文献
993.
Lei Jiang Haizhen Ding Prof. Dr. Siyu Lu Dr. Ting Geng Prof. Dr. Guanjun Xiao Prof. Dr. Bo Zou Prof. Dr. Hong Bi 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(25):10072-10077
Photoactivation in CdSe/ZnS quantum dots (QDs) on UV/Vis light exposure improves photoluminescence (PL) and photostability. However, it was not observed in fluorescent carbon quantum dots (CDs). Now, photoactivated fluorescence enhancement in fluorine and nitrogen co-doped carbon dots (F,N-doped CDs) is presented. At 1.0 atm, the fluorescence intensity of F,N-doped CDs increases with UV light irradiation (5 s–30 min), accompanied with a blue-shift of the fluorescence emission from 586 nm to 550 nm. F,N-doped CDs exhibit photoactivated fluorescence enhancement when exposed to UV under high pressure (0.1 GPa). F,N-doped CDs show reversible piezochromic behavior while applying increasing pressure (1.0 atm to 9.98 GPa), showing a pressure-triggered aggregation-induced emission in the range 1.0 atm–0.65 GPa. The photoactivated CDs with piezochromic fluorescence enhancement broadens the versatility of CDs from ambient to high-pressure conditions and enhances their anti-photobleaching. 相似文献
994.
Linwen Zhang Dr. Ran Long Dr. Yaoming Zhang Delong Duan Prof. Yujie Xiong Dr. Yajun Zhang Prof. Yingpu Bi 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(15):6283-6288
Single-atom catalysts are promising platforms for heterogeneous catalysis, especially for clean energy conversion, storage, and utilization. Although great efforts have been made to examine the bonding and oxidation state of single-atom catalysts before and/or after catalytic reactions, when information about dynamic evolution is not sufficient, the underlying mechanisms are often overlooked. Herein, we report the direct observation of the charge transfer and bond evolution of a single-atom Pt/C3N4 catalyst in photocatalytic water splitting by synchronous illumination X-ray photoelectron spectroscopy. Specifically, under light excitation, we observed Pt−N bond cleavage to form a Pt0 species and the corresponding C=N bond reconstruction; these features could not be detected on the metallic platinum-decorated C3N4 catalyst. As expected, H2 production activity (14.7 mmol h−1 g−1) was enhanced significantly with the single-atom Pt/C3N4 catalyst as compared to metallic Pt-C3N4 (0.74 mmol h−1 g−1). 相似文献
995.
Beibei Zhang Xiaojuan Huang Yan Zhang Prof. Gongxuan Lu Prof. Lingjun Chou Prof. Yingpu Bi 《Angewandte Chemie (Weinheim an der Bergstrasse, Germany)》2020,132(43):19152-19157
Understanding the origin of formation and active sites of oxygen evolution reaction (OER) cocatalysts is highly required for solar photoelectrochemical (PEC) devices that generate hydrogen efficiently from water. Herein, we employed a simple pH-modulated method for in situ growth of FeNi oxyhydroxide ultrathin layers on BiVO4 photoanodes, resulting in one of the highest currently known PEC activities of 5.8 mA cm−2 (1.23 VRHE, AM 1.5 G) accompanied with an excellent stability. More importantly, both comparative experiments and density functional theory (DFT) studies clearly reveal that the selective formation of Bi−O−Fe interfacial bonds mainly contributes the enhanced OER activities, while the construction of V−O−Ni interfacial bonds effectively restrains the dissolution of V5+ ions and promotes the OER stability. Thereby, the synergy between iron and nickel of FeNi oxyhydroxides significantly improved the PEC water oxidation properties of BiVO4 photoanodes. 相似文献
996.
Bi Peng Xie Duan Lin Wei Wang Kai Liu Jiang-Ping Tang Yong-Jian Yang Xiang-Dong Lei Hai-Le 《中国物理 B》2013,22(3):34401-034401
A specific-wavelength infrared (IR) light (λ=3140 nm) was irradiated into a solid D2 ice prepared in a cylinder target cell. The temperature in the solid D2 ice oscillated periodically with a high amplitude when irradiated by the IR light. The temperature oscillation has been well explained based on the two-dimensional heat transfer theory plus the IR-irradiation effect. The transmission optical imaging reveals that such a temperature oscillation is favorable to recrystallize the solid D2 ice from multicrystal to quasi single crystal. This suggests an efficient method to layer the solid hydrogen-isotope ice for the inertial-confinement-fusion (ICF) experiments. 相似文献
997.
Shi Zhou Chuan‐Bi Li Qing‐Wei Wang Seik Weng Ng 《Acta Crystallographica. Section C, Structural Chemistry》2011,67(7):m224-m226
In the title cadmium(II) complex, [Cd(C8H4O5)(C14H14N4)(H2O)]n, the 5‐hydroxybenzene‐1,3‐dicarboxylate (5‐OH‐1,3‐bdc) and 1,4‐bis(imidazol‐1‐ylmethyl)benzene (1,4,‐bix) ligands bridge water‐coordinated CdII atoms to generate a three‐dimensional network. Two carboxylate groups from different ligands function as O,O′‐chelates, while two imidazole N atoms from different ligands coordinate in a monodentate fashion, and one water molecule completes the seven‐coordinate pentagonal bipyramid around the CdII atom, in which the N atoms occupy the axial sites and the O atoms occupy the equatorial sites. The overall architecture is a twofold interpenetrated CdSO4‐type framework. The two crystallographically equivalent frameworks are linked by O—H...O hydrogen bonds between the water, hydroxy and carboxylate groups. 相似文献
998.
In this paper, we consider an insurance company which has the option of investing in a risky asset and a risk-free asset, whose price parameters are driven by a finite state Markov chain. The risk process of the insurance company is modeled as a diffusion process whose diffusion and drift parameters switch over time according to the same Markov chain. We study the Markov-modulated mean-variance problem for the insurer and derive explicitly the closed form of the efficient strategy and efficient frontier. In the case of no regime switching, we can see that the efficient frontier in our paper coincides with that of [10] when there is no pure jump. 相似文献
999.
The paper proposes methodology for resource allocation and target setting based on DEA (data envelopment analysis). It deals with organization can be modeled as consisting of several production units, each of which has parallel production lines. The previous studies in the DEA literature only deal with reallocating/allocating organizational resources to production units and set targets for them. In their researches, the production unit is treated as a black box. In such circumstances, how to arrange the production at production unit level is not clear. This paper serves to generate resource allocation and target setting plan for each production unit by opening the black box. The proposed model exploits production information of production lines in generating production plans. The resulting plan has following characteristics: (1) the performance of each production lines are evaluated under common weights; (2) the weights chose for evaluation keep the efficiency of the entire unit not worse off; (3) the worst behaved production line in the production unit under evaluation are improved as much as possible. Finally, the real data of a production system extracted from extant literature are used to demonstrate the proposed method. 相似文献
1000.
研究了基于结构性改变的光子晶体光纤光栅的热激法制备工艺,理论分析了此种工艺的成栅原理,采用热传导理论和有限元法研究了制备过程中光子晶体光纤中的温度场分布,以及包层空气孔结构和激光参数对成栅效果的影响.研究结果表明,利用光子晶体光纤包层空气孔周期性塌缩可以形成光栅;采用两点热激法时,能够实现能量在光纤径向均匀分布,轴向近似于高斯分布;包层气孔结构加速了成栅过程,相同光斑尺寸下,光纤塌缩所需激光功率随气孔层数和气孔半径的增大而减小;最后,对包层空气孔结构为1层到7层的光子晶体光纤热激过程进行仿真,得到了空气填
关键词:
光纤光栅
光子晶体光纤
热激法
有限元法 相似文献