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61.
Thermodynamics and dynamics of metallic glass formers: their correlation for the investigation on potential energy landscape 总被引:3,自引:0,他引:3
Great progress has been made in basic features of the potential energy landscape (PEL) theoretically. The present work, however, attempts to cast new light on it from experimental aspects. By a survey of experimental data related to thermodynamics or dynamics of metallic glass-forming liquids, it is found that the increased rate of excitation of vibrational entropy at glass transition tends to increase the rate of generation of configurational part. Although for the type of metallic materials a generally positive relationship exists between the density of the energy minima at glass transition and the liquid fragility strength, just as expected, our main attention is paid to the phenomenon of the scattering of the slopes. Analysis shows that the phenomenon results from the different average height of energy barriers between minima near glass transition. Investigation on the PdNiP metallic system indicates that the mismatch entropy is a dominant factor in the barrier height: a large value of it results in low energy barriers. Our previous work on the AlNiCe system gives the support to this finding. 相似文献
62.
神经网络的函数逼近能力分析 总被引:12,自引:0,他引:12
本文综述了多层前传网络(MLP)及径向基函数网络(RBF)对函数任意精度逼近的能力,比较了两种网络的最佳逼近特性。对激活函数类的扩充作了介绍,并说明有限数值精度对函数逼近能力实现的影响。 相似文献
63.
Li-an Bian Peiguo Liu Qihui Zhou Chenxi Liu Hanqing Liu Song Zha 《Optical and Quantum Electronics》2018,50(5):220
Total absorption is realized theoretically in a graphene-outside-cavity resonator. The structure is composed of the FP-Fano hybrid resonance cavity. Changing the thickness of grating exciting Fano resonance, the absorption-mode number can be tuned effectively. For the focused double-mode absorption, the resonances behave insensitively with the variation of chemical potential of graphene. Varying the geometry of grating can control the coupling extent of two modes. Also, by manipulating the period number of two-side multilayers around graphene, the absorption, shift and number of modes are governed. 相似文献
64.
Xiaolong Shi Xiaoru Zhao Libing Duan Huinan Sun Jinming Liu Xiaojun Bai Mengmeng Guan Mengmeng Cao Jinru Liu 《Journal of Sol-Gel Science and Technology》2013,66(2):301-305
Sn-doped ZnO (SZO) thin films are deposited by sol–gel dip-coating method with Sn content at 0 at.% and 1–15 at.% with an increment of 2 at.%. The structure and luminescence of the films are investigated. X-ray diffraction results indicate that all the SZO samples show preferential orientation along the (002) direction, and the scanning electron microscope exhibits that the surface morphology of the films change from nanoparticles to nanorods with increasing Sn concentration. X-ray photoelectron spectroscopy reveals that Sn exists as valence of +4 in the matrix. The photoluminescence peaks at 381 and 398 nm are observed in all the samples. The ratio of intensity of peak at 381 nm to that of peak at 398 nm differed markedly. The intensity of peak at 398 nm might be due to the response for the Sn atoms, while the intensity of peak at 381 nm is probably related to the quantum size effect. 相似文献
65.
66.
Wang Kang Xingqiong Du Lanzhi Wang Lijuan HU Yuhuan Dong Yanqing Bian Yuan Li 《中国化学》2013,31(10):1305-1314
Our studies examined the structural features responsible for the antifungal activity of 2-ethoxycarbonyl-1,5- benzothiazepine (7a). Three series of 1,5-benzothiazepine derivatives were synthesized and screened for their antifungal activity. The results suggested that the ethoxycarbonyl group at the 2 position and the imine moiety on the seven-membered ring are essential for activity. The most potent of the synthesized analogues (7a, 7b) were further studied by evaluating their cytotoxicity and mode of action (for 7a). The results showed that compounds 7a and 7b were relatively safe for BV2 cells, but compound 7a interfered with Cryptococcus neoformans cell wall integrity by increasing the chitinase activity. Therefore, compound 7a was considered safe as an antifungal agent for animal cells. 相似文献
67.
68.
An easily prepared tetraphosphine N,N,N′,N′‐tetra(diphenylphosphinomethyl)‐1,2‐ethylenediamine (1) combined with PdCl2 affords an efficient catalytic system for Suzuki cross‐coupling of aryl and heteroaryl bromides. A high turnover number of 750 000 is obtained with the catalyst loading as low as 1 ppm. This catalyst system exhibits good stability and longevity. In this study, a broad scope of substrates is investigated and satisfactory yields are obtained. Copyright © 2012 John Wiley & Sons, Ltd. 相似文献
69.
Under certain conditions on co-dimension and curvature tensors, the image of some CR or holomorphic maps are proved to be totally geodesic. 相似文献
70.
Dr. Ruisong Tian Dr. Chao Wang Dr. Weijie Chi Prof. Dr. Jiangli Fan Prof. Dr. Jianjun Du Dr. Saran Long Prof. Dr. Lianying Guo Prof. Dr. Xiaogang Liu Prof. Dr. Xiaojun Peng 《Chemistry (Weinheim an der Bergstrasse, Germany)》2021,27(67):16707-16715
Upconversion luminescent (UCL) triggered photodynamic therapy (PDT) affords superior outcome for cancer treatment. However, conventional UCL materials which all work by a multiphoton absorption (MPA) process inevitably need extremely high power density far over the maximum permissible exposure (MPE) to laser. Here, a one-photon absorption molecular upconversion sensitizer Cy5.5-Br based on frequency upconversion luminescent (FUCL) is designed for PDT. The unusual super heavy atom effect (SHAE) in Cy5.5-Br strongly enhances its spin-orbit coupling (0.23 cm−1), triplet quantum yield (11.1 %) and triplet state lifetime (18.8 μs) while the potential hot-band absorption of Cy5.5-Br is well maintained. Importantly, Cy5.5-Br can efficiently target the tumour site and kill cancer cells by destroying mitochondria under a biosafety MPE to 808 nm laser. The photostability and antitumor results are obviously superior to that of a Stokes process. This work provides a design criterion for FUCL dyes to realize effective PDT upon a biosafety optical density, possibly bringing more clinical benefits than conventional MPA materials. 相似文献