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101.
The anti-friction and wear-resistant performances of bonded MoS2 solid lubricating films filled with nano-LaF3 filler were investigated under in drying wear conditions, the corrosion-resistant performances of bonded lubricating films was evaluated according to ASTM-B117, and the characteristics of the bonded lubricating films were examined by TEM and elemental x-ray map. The wear-resistant performance of the bonded lubricating films filled with nano-LaF3 filler increases with increasing content of nano-LaF3 filler within a content range between 0 and 5 wt%, whereas the bonded lubricating films filled with 0.5–1 wt% micro-LaF3 filler exhibit the better wear-resistant performances. The incorporation of both nano-LaF3 and micro-LaF3 filler leads the increase of the coefficient of friction of the bonded lubricating films. The LaF3 filler can improve the corrosion-resistant performance of the bonded MoS2 solid lubricating films, whereas the incorporation of nano-LaF3 filler is more effective to improve the corrosion-resistant performance of the bonded lubricating films than micro-LaF3 filler. The improvement in the wear-resistant and corrosion-resistant performances of the bonded lubricating films by the incorporation of the nano-LaF3 filler is attributed to the strengthened interfacial bonding among the nano-LaF3 and the MoS2 lubricant and the polymeric matrix. However, a too high mass fraction of the nano-LaF3 filler in the bonded lubricating films will increase surface and interface defects, and lead the worsening of corrosion-resistant performance of the bonded lubricating films. 相似文献
102.
Kongkai Zhu Junyan Lu Zhongjie Liang Xiangqian Kong Fei Ye Lu Jin Heji Geng Yong Chen Mingyue Zheng Hualiang Jiang Jun-Qian Li Cheng Luo 《Journal of computer-aided molecular design》2013,27(3):247-256
New Delhi metallo-β-lactamase-1 (NDM-1) has emerged as a major global threat to human health for its rapid rate of dissemination and ability to make pathogenic microbes resistant to almost all known β-lactam antibiotics. In addition, effective NDM-1 inhibitors have not been identified to date. In spite of the plethora of structural and kinetic data available, the accurate molecular characteristics of and details on the enzymatic reaction of NDM-1 hydrolyzing β-lactam antibiotics remain incompletely understood. In this study, a combined computational approach including molecular docking, molecular dynamics simulations and quantum mechanics/molecular mechanics calculations was performed to characterize the catalytic mechanism of meropenem catalyzed by NDM-1. The quantum mechanics/molecular mechanics results indicate that the ionized D124 is beneficial to the cleavage of the C–N bond within the β-lactam ring. Meanwhile, it is energetically favorable to form an intermediate if no water molecule coordinates to Zn2. Moreover, according to the molecular dynamics results, the conserved residue K211 plays a pivotal role in substrate binding and catalysis, which is quite consistent with previous mutagenesis data. Our study provides detailed insights into the catalytic mechanism of NDM-1 hydrolyzing meropenem β-lactam antibiotics and offers clues for the discovery of new antibiotics against NDM-1 positive strains in clinical studies. 相似文献
103.
Wenbo Wu Dr. Guohua Xu Prof. Conggang Li Prof. Gui Yu Prof. Yunqi Liu Prof. Cheng Ye Prof. Jingui Qin Prof. Zhen Li 《Chemistry (Weinheim an der Bergstrasse, Germany)》2013,19(21):6874-6888
Through the combination of the divergent and convergent approaches, coupled with the utilization of the powerful Sharpless “click‐chemistry” reaction, two series of sulfonyl‐based high‐generation NLO dendrimers were conveniently prepared with high purity and in satisfactory yields. Thanks to the perfect three‐dimensional (3D) spatial isolation from the highly branched structure and the isolation effect of the exterior benzene moieties and the interior triazole rings, these dendrimers exhibited large second harmonic generation coefficient (d33) values up to 181 pm V?1, which, to the best of our knowledge, is the highest value so far for polymers containing sulfonyl‐based chromophore moieties. Meanwhile, compared with the nitro‐chromophore‐based analogues, their optical transparency and NLO stability were improved in a large degree, due to the lower dipole moment (μ) and the special main‐chain structure of sulfonyl‐based chromophore in these dendrimers. 相似文献
104.
Preparation and characterization of ZrCO/C composite aerogels 总被引:1,自引:0,他引:1
Li Ye Wenfeng Qiu Hao Li Aijun Zhao Tao Cai Tong Zhao 《Journal of Sol-Gel Science and Technology》2013,65(2):150-159
Zr-containing organic aerogels were synthesized by ligand substitution reaction of polyzirconoxone and 2, 4-dihydroxybenzoic acid, followed by polymerization with formaldehyde, and then supercritical drying using CO2. After carbonization and carbothermal reduction under an argon atmosphere, ZrCO/C composite aerogels with controllable zirconium content (47.8–78.6 wt%) were obtained. The carbothermal reduction was substantially completed at 1,500 °C, and the obtained ZrCO/C composite aerogels exhibit low oxygen contents (9.4–6.7 wt%) and high surface areas (589–147 m2/g). Pore morphologies of the ZrCO/C composite aerogels were investigated in detail by nitrogen sorption measurements, scanning electron microscopy and its associated energy-dispersive X-ray microanalysis measurements. The results show that the aerogels are composed of carbon framework and Zr-conglomerations, and the surface area of aerogel is severely affected by its zirconium content. The presence of reductive ZrC crystals can greatly enhance the oxidation resistance ability of amorphous carbon framework and prevent collapse. 相似文献
105.
Microscopic structures of Zn(II) adsorbed on anatase TiO2 surface with different densities were studied using extended X-ray absorption fine structure (EXAFS) spectroscopy and density functional theory (DFT) calculation. Quantitative analysis of the EXAFS spectra showed that microscopic structures of Zn(II) were fourfold coordinated complexes, and different microscopic structures were present of the solid surface. Three modes of corner–corner/sharing-corner/sharing-edge adsorptions on anatase (101) face cluster were calculated by the DFT method. The results from DFT method were consistent with the EXAFS fittings. The optimized Zn–O average distance of the Zn–O tetrahedron was determined as about 2.00 Å. The Zn–Ti distance was 3.69 Å for the corner–corner adsorption, 3.35 Å for the sharing-corner adsorption, and 3.02 Å for the sharing-edge adsorption. According to the adsorption energies calculated by the DFT method, the microscopic structure of corner–corner adsorption was less stable than those of the other adsorption modes. With the increasing adsorption density, the corner–corner adsorption mode would be enhanced more intensively than the other adsorption modes. 相似文献
106.
New methallylsilanated phosphorylcholine (MASPCs) were synthesized via a copper-catalyzed ‘click’ reaction and demonstrated excellent moisture stability. Hydroxylated silicon compounds, silanol, and silica were grafted or modified by MASPCs in the presence of triflic acid (TfOH) and they possessed a good grafting efficiency and high loading rate. 相似文献
107.
A silver-catalyzed reaction of 2-alkynylbenzaldoxime with arylsulfonyl chloride proceeds smoothly at room temperature to afford 4-tosyloxyisoquinolines in moderate to good yields. Additionally, the resulting 4-tosyloxyisoquinolines could be further elaborated through palladium-catalyzed coupling reactions leading to diverse isoquinolines. 相似文献
108.
109.
Ye F Fernandez-Baca JA Fishman RS Ren Y Kang HJ Qiu Y Kimura T 《Physical review letters》2007,99(15):157201
The spin-wave excitations of the geometrically frustrated triangular lattice antiferromagnet CuFeO2 have been measured using high resolution inelastic neutron scattering. Antiferromagnetic interactions up to third nearest neighbors in the ab plane (J1, J2, J3, with J{2}/J{1} approximately 0.44 and J{3}/J{1} approximately 0.57), as well as out-of-plane coupling (J{z}, with J{z}/J{1} approximately 0.29) are required to describe the spin-wave dispersion relations, indicating a three-dimensional character of the magnetic interactions. Two energy dips in the spin-wave dispersion occur at the incommensurate wave vectors associated with multiferroic phase and can be interpreted as dynamic precursors to the magnetoelectric behavior in this system. 相似文献
110.
We report on the dynamics of photodegradation and subsequent recovery of two-photon fluorescence in a dye-doped polymer. The energy dependence suggests that photodegradation is a linear process, while recovery is entropic. Such recovery could be useful to high-intensity devices such as two-photon absorbers, which can be used in many applications. 相似文献