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51.
Tetsuro Fujita 《中国化学快报》2007,18(2):175-177
A new highly conjugated alkaloid of veratramine type, 225,25S,5α-veratramine-7(8),12(14)-diene-3β,13β,23β-triol-6-one (1), was isolated from the bulbs of Fritillaria hupehensis Hsiao et K.C. Hsia. Its structure was determined on the basis of spectroscopic evidences. 相似文献
52.
Ruan Jianmiao Zhu Xiangrong 《高校应用数学学报(英文版)》2005,20(4):448-454
It is shown that the maximal singular integral operator with kernels satisfying Ho rmander＇s condition is of weak type （1,1） and L^p （1〈p〈∞） bounded without assuming that the underlying measure p is doubling. Under stronger smoothness conditions,such estimates can be obtained by using a Cotlar＇s inequality. This inequality is not applicable here and it is noticeable that the Cotlar＇s inequality maybe fails under Hormander＇s condition. 相似文献
53.
In this paper, we study the convergence of Calabi–Yau manifolds under Kähler degeneration to orbifold singularities and complex degeneration to canonical singularities (including the conifold singularities), and the collapsing of a family of Calabi–Yau manifolds. 相似文献
54.
In this article ,we chiefly discuss optical part and photoelectrical part, and analyze the result data to make out the relationship between pinhole and special resolution and the influence of PMT on the result data. 相似文献
55.
Kui Wu Zhe Li Jing Guo Yongchuan Xiao Huajuan Qi Wei Dong Shengping Ruan Weiyou Chen Yu Chen 《Optik》2014
An integrated tunable optical filter (TOF) based on thermo-optic effect in silicon on insulator (SOI) rib waveguide is designed and simulated. The device is comprised of two high refractivity contrast Si/Air stacks, functioning as high reflectivity of DBRs (distributed Bragg reflectors) and separating by a variable refractive index polymer Fabry–Perot (F–P) cavity. The designed device exhibits Q = 24077, FWHM = 0.065 nm and finesse = 566. Wavelength tuning is achieved through thermal modulation of refractive variation of the cavity. As the cavity polymer is heated, the refractive index of the cavity decreases. When the temperature of cavity polymer changes within 105, the central wavelength gets a continuous 35 nm shift from 1530 nm to 1565 nm, which can operate the whole C-band in the WDM (wavelength division multiplexing) networks. Moreover, by calculating, the tuning sensitivity is about 0.33 nm/°C. Owing to the compact size and excellent characteristics of integration, the proposed component has a promising utilization in spectroscopy and optical communication. 相似文献
56.
Shuyi Xie;Wenqi Ruan;Qianqian Liu;Yongfan Zhang;Xiangyu Guo;Kaining Ding; 《International journal of quantum chemistry》2024,124(9):e27379
Production of ammonia (NH3) by electrocatalytic reduction of nitrate (NO3RR) not only eliminates harmful pollution, but also provides a way to reduce the energy consumption associated with predominated Haber-Bosch process. However, realization of this process still faces many challenges because of the complexity of the reaction mechanism. Here we investigated the catalytic activity and selectivity of a series of graphdiyne supported single atom catalysts (SACs), namely TM/GDY, for the reduction of NO3−$$ {mathrm{O}}_3^{-} $$ to NH3 by first-principles calculations. Among the 10 SACs studied, Fe/GDY was found to have good catalytic performance, consistent with the fact that the Fe-doped GDY molecular layer was located near the top of the volcano plot, with a reaction limit potential of −0.44 V and showed excellent selectivity in inhibiting the competitive hydrogen evolution reaction (HER). The formation of the by-products NO2, NO, N2O and N2 on Fe/GDY requires a considerable energy barrier, which ensures high selectivity. Furthermore, detailed electronic property analyses indicate that the GDY can work as an electron repository to effectively balance the charge transfers during the reaction process. This study not only offers an eligible NO3RR electrocatalyst but also provides an atomic understanding of the mechanisms of the NO3RR process behind. 相似文献
57.
Na Li Honggang Nie Liping Jiang Guihua Ruan Fuyou Du Huwei Liu 《Journal of separation science》2020,43(15):3146-3163
The structural information and spatial distribution of molecules in biological tissues are closely related to the potential molecular mechanisms of disease origin, transfer, and classification. Ambient ionization mass spectrometry imaging is an effective tool that provides molecular images while describing in situ information of biomolecules in complex samples, in which ionization occurs at atmospheric pressure with the samples being analyzed in the native state. Ambient ionization mass spectrometry imaging can directly analyze tissue samples at a fairly high resolution to obtain molecules in situ information on the tissue surface to identify pathological features associated with a disease, resulting in the wide applications in pharmacy, food science, botanical research, and especially clinical research. Herein, novel ambient ionization techniques, such as techniques based on spray and solid‐liquid extraction, techniques based on plasma desorption, techniques based on laser desorption ablation, and techniques based on acoustic desorption were introduced, and the data processing of ambient ionization mass spectrometry imaging was briefly reviewed. Besides, we also highlight recent applications of this imaging technology in clinical researches and discuss the challenges in this imaging technology and the perspectives on the future of the clinical research. 相似文献
58.
Zhiguo Chen Prof. Xiaoli Fan Zihan Shen Xiaopeng Ruan Lan Wang Hanghang Zeng Jiahui Wang Yurong An Yan Hu 《ChemCatChem》2020,12(16):4059-4066
MXenes have attracted great attention in the fields of energy conversion and catalysis, and have proved to be an effective supporting material for single atom catalysts (SACs). In the present study, we investigated the catalytic activity of a series mono-atomic transition-metal atoms supported by MXenes M2NO2 for oxygen evolution reaction (OER) via first principle calculation. Particularly, single atom Cu site on Ti2NO2 having the lowest overpotentials of 0.24 V and bonding with the reaction intermediates moderately, is the most active SAC for OER. Energetically, Cu atom prefers to be mono-atomically anchored on Ti2NO2 instead of aggregating. Plus, Cu anchoring enhance the electronic states around Fermi level. Additionally, ab-initio molecular dynamics simulations show that Cu atom is anchored on Ti2NO2, stable and isolatable at 300 K. Studies on the small molecule adsorption on Cu-Ti2NO2 further prove the potential applications of Cu−Ti2NO2 as active SACs for OER. Our results broaden the perception of MXenes and guide the exploration of non-noble metal based OER electrocatalysts. 相似文献
59.
Zhichao Hao Dr. Zhengang Guo Dr. Mengnan Ruan Prof. Jing Ya Yong Yang Dr. Xiangfeng Wu Prof. Zhifeng Liu 《ChemCatChem》2021,13(1):271-280
The enhanced separation and injection efficiencies of photogenerated carriers is essential to improve the photoelectrochemical (PEC) performance of WO3 photoanode. In this work, we firstly synthesized WO3/NiCo2O4 heterojunction through simple hydrothermal-annealing method as well as investigate the effect and mechanism of NiCo2O4 on WO3 for PEC performances. The measurements demonstrate that the nano-needle NiCo2O4 grown on the surface of WO3 induces the bimetallic Ni/Co redox reaction sites extensively exposed to the electrolyte, which is beneficial to enhance the PEC performances of WO3 photoanode, such as photocurrent density improved by four times (0.84 mA/cm2 at 1.23 V vs. RHE) as well as more negative initial potential (∼280 mV) in contrast to bare WO3. Further investigation shows the remarkable enhancement of PEC performances is attributed to improved surface reaction kinetics, the enhanced injection efficiency and separation efficiency of photogenerated carriers due to the co-catalyst effect of NiCo2O4 and the formation of WO3/NiCo2O4 heterojunction. This work provides reference for application of heterojunction with co-catalyst function, which is beneficial to the development and application of similar structures. 相似文献
60.
Peng Liu Hui Ruan Tiantian Li Jiaqi Chen Fuqiu Ma Duoqiang Pan Wangsuo Wu 《Molecules (Basel, Switzerland)》2021,26(4)
The low cost β-zeolite and ethylenediamine modified β-zeolite (EDA@β-zeolite) were prepared by self-assembly method and used for Cu(II) removal from contaminated aqueous solution. Removal ability of β-zeolite toward Cu(II) was greatly improved after ethylenediamine (EDA) modification, the removal performance was greatly affected by environmental conditions. XPS results illustrated that the amide group played important role in the removal process by forming complexes with Cu(II). The EDA@β-zeolite showed desirable recycling ability. The finding herein suggested that the proposed composite is a promising and suitable candidate for the removal of Cu(II) from contaminated natural wastewater and aquifer. 相似文献