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991.
Bin Li Bin Wang Xiayang Huang Lu Dai Lei Cui Jian Li Xueshun Jia Chunju Li 《Angewandte Chemie (International ed. in English)》2019,58(12):3885-3889
Herein, two new classes of macrocyclic compounds, terphen[n]arenes (TPns) (n=3–6) and quaterphen[n]arenes (QPns) (n=3–6), were designed and synthesized by a one‐step condensation reaction in relatively high yields. They comprise 2,2′′‐dimethoxy terphenyl and 2,2′′′‐dimethoxy quaterphenyl monomers, respectively, linked by methylene bridges. Given their long and rigid monomers, TPns and QPns have much larger cavities and better self‐assembly properties than classic macrocycles. More interestingly, the cyclic pentamers and hexamers TP5, TP6, QP5, and QP6 formed supramolecular organogels, which were composed of interwoven fibers, nanosheets, or entangled macropore networks formed by multiple face‐to‐face and edge‐to‐face π???π stacking interactions. The xerogel materials effectively captured volatile iodine, not only in aqueous media but also in the gaseous state, and could be recycled multiple times without obvious loss in performance. 相似文献
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Two new sesquiterpenes (1–2), along with one known sesquiterpene (3), were isolated from cultures of the higher fungus Pholiota nameko. The structures of new compounds were elucidated by extensive spectroscopic methods. The known compound was identified by comparing its spectroscopic data with those reported in the literature. All compounds were evaluated for their cytotoxicities against five human cancer cell lines. 相似文献
996.
Vibration mechanism of a mistuned bladed-disk 总被引:1,自引:0,他引:1
For coupling vibration of the mistuned bladed-disk in aeroengine, the vibration differential equation of the system is established using component-mode synthesis methods. Experimental mode analysis and mode correction are used to calculate some low-order modes of tuned blade and the disk with cone-flange. The models of actual mistuned bladed-disk is constructed by exerting some small perturbation on the mode stiffness of blades. The forced vibration experimentation of an actual mistuned bladed-disk in non-rotating status is carried out to verify the vibration model and calculation formulae. The results show that excessive vibration response of a single blade is caused by blade mistuning, and the random mistuning distribution of a small frequency difference is more profitable than other arrangements for depressing the maximal vibration level of the hapless blade. In this study, the better natural frequency difference amplitude of blades and the right working frequency range of aeroengine are also suggested according to the result analysis of several numerical calculations. 相似文献
997.
Tingjian Jia Tingchao He Pengwei Li Yujun Mo Yuting Cui 《Optics & Laser Technology》2008,40(7):936-940
The nonlinear optical properties of metal Au and Ag colloidal solutions prepared by the chemical reaction method were investigated by a single beam Z-scan technique. Under CW 633 nm excitation, the Au and Ag colloidal solutions exhibited a large thermal-induced refractive index n2. At the same time, the thermo-optic coefficients dn/dT of the Au and Ag colloidal solutions were obtained. The mechanism responsible for the process of nonlinear refraction was discussed in term of laser heating effect. 相似文献
998.
Effects of distributed birefringence on fiber Bragg grating under non-uniform transverse load 总被引:1,自引:0,他引:1
Yiping Wang Na Chen Binfeng Yun Zhuyuan Wang Changgui Lu Yiping Cui 《Optics & Laser Technology》2008,40(8):1037-1040
Many theoretical and experimental studies have been developed to characterize the spectral response of an optical fiber Bragg grating (FBG) in axial strain fields in recent years. However, comparatively few works were devoted to the evolution of the spectrum when a FBG is subjected to non-uniform transverse load. In this paper, the effects of distributed birefringence on FBG under non-uniform transverse load are analyzed and a numerical simulation based on the piecewise-uniform approach is also discussed to simulate the responses of FBG under some typical non-uniform transverse strain fields. Experiment was carried out using different loads applied at different locations of the FBG. Good agreements between experimental results and numerical simulations have been obtained. 相似文献
999.
The interaction of cobalt atoms with silicon (1 1 1) surface has been investigated by means of scanning tunneling microscopy (STM) and low-energy electron diffraction (LEED). Besides the Co silicide islands, we have successfully distinguished two inequivalent Co-induced reconstructions on Si(1 1 1) surface. Our high-resolution STM images provide some structural properties of the two different derived phases. Both of the two phases seem to form islands with single domain. The new findings will help us to understand the early stage of Co silicide formations. 相似文献
1000.
Chengyun Cui 《Applied Surface Science》2008,254(20):6537-6542
The effects of laser surface irradiation on microstructure of AISI 304 stainless steel were investigated. The stainless steel surface was characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM). XRD patterns indicated that different oxides, such as chromium oxides and manganese oxides were fabricated successfully on the surface of the stainless steel by Nd:YAG pulsed laser irradiation. The effects of the growth conditions such as the laser power density on the morphologies of the different oxides have been investigated. From the FESEM, EDS (energy-dispersive spectrum) and TEM observations, the oxides with triangle-like, quadrangular and hexagonal morphologies have been fabricated successfully. The XPS was used to verify the formed oxides which had been detected by the XRD patterns. It was considered that laser power density had a critical role in the formation of different oxides. 相似文献