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排序方式: 共有290条查询结果,搜索用时 15 毫秒
1.
In this work, we report the preparation and characterization of novel dye doped fluorophore Eosin yellowish silica nanoparticles
(ESNPs). We synthesized ESNPs by the St?ber method via encapsulation of Eosin Yellowish in silica particles by the condensation
of tetraethyl orthosilicate under alkaline condition at room temperature. The resulted ESNPs were characterized by transmission
electron microscopy, atomic force microscopy; UV–Visible, fluorescence and Fourier transform infrared spectroscopy. The sizes
of the nanoparticles have been found to be 300.0 (±1.0), 400.0 (±1.1) and 500.0 (±5.2) nm depending the reaction conditions
under which they were synthesized. Furthermore, because of intense light emission, the ESNPs were used as fluorophore in a
peroxyoxalate chemiluminescence system. The effect of solvent and concentrations of necessary reagents, bis(2,4,6-trichlorophenyl)oxalate,
sodium salicylate, hydrogen peroxide and the effects of size of the ESNP and temperature on the luminescence efficiency of
the system were examined. The activation kinetic parameters of the system were also evaluated from the temperature investigation. 相似文献
2.
Marzieh Peyravi Afshin Montakhab Nematollah Riazi Abdorrasoul Gharaati 《The European Physical Journal B - Condensed Matter and Complex Systems》2009,72(2):269-277
The periodic and step-like solutions of the double-Sine-Gordon equation are investigated, with different initial conditions and for various values of the potential parameter epsilon. We plot energy and force diagrams, as functions of the inter-soliton distance for such solutions. This allows us to consider our system as an interacting many-body system in 1+1 dimension. We therefore plot state diagrams (pressure vs. average density) for step-like as well as periodic solutions. Step-like solutions are shown to behave similarly to their counterparts in the Sine-Gordon system. However, periodic solutions show a fundamentally different behavior as the parameter epsilon is increased. We show that two distinct phases of periodic solutions exist which exhibit manifestly different behavior. Response functions for these phases are shown to behave differently, joining at an apparent phase transition point. 相似文献
3.
Yang Zhao Yue‐Jiao Zhang Jin‐Hui Meng Shu Chen Rajapandiyan Panneerselvam Chao‐Yu Li Sain Bux Jamali Xia Li Zhi‐Lin Yang Jian‐Feng Li Zhong‐Qun Tian 《Journal of Raman spectroscopy : JRS》2016,47(6):662-667
Silver nanoparticles (Ag NPs) enjoy a reputation as an ultrasensitive substrate for surface‐enhanced Raman spectroscopy (SERS). However, large‐scale synthesis of Ag NPs in a controlled manner is a challenging task for a long period of time. Here, we reported a simple seed‐mediated method to synthesize Ag NPs with controllable sizes from 50 to 300 nm, which were characterized by scanning electron microscopy (SEM) and UV–Vis spectroscopy. SERS spectra of Rhodamine 6G (R6G) from the as‐prepared Ag NPs substrates indicate that the enhancement capability of Ag NPs varies with different excitation wavelengths. The Ag NPs with average sizes of ~150, ~175, and ~225 nm show the highest SERS activities for 532, 633, and 785‐nm excitation, respectively. Significantly, 150‐nm Ag NPs exhibit an enhancement factor exceeding 108 for pyridine (Py) molecules in electrochemical SERS (EC‐SERS) measurements. Furthermore, finite‐difference time‐domain (FDTD) calculation is employed to explain the size‐dependent SERS activity. Finally, the potential of the as‐prepared SERS substrates is demonstrated with the detection of malachite green. Copyright © 2016 John Wiley & Sons, Ltd. 相似文献
4.
5.
Alireza Khorsandi Saeed Ghavami Sabouri Somaieh Fathi Marzieh Asadnia-Jahromi 《Optics & Laser Technology》2011,43(5):956-959
We have reported a modified V-shaped external cavity, which is constructed around a commercial diode laser operating at a center wavelength of λ=785 nm by adding a new coated glass plate with about 50% reflectivity to the cavity. This allows simultaneous dual-wavelengths operation in the vicinity of Δνmin=0.18 THz to Δνmax=0.22 THz, which can be used as laser source for terahertz generation either for semiconductor devices or nonlinear schemes. 相似文献
6.
Polyoxometalates (POM) supported on zirconia, H3PW12O40/ZrO2, were prepared by incorporating polyphosphotungstate into a zirconia matrix via sol-gel technique that involving the hydrolysis of zirconium (IV) n-butoxide, Zr (n-OBu)4, as the ZrO2 source. This insoluble and readily separable catalyst was characterized by using XRD, FT-IR, SEM, and UV diffuse reflectance spectroscopy (UV-DRS), indicating that the polyphosphotungstate was chemically attached to the zirconia supports, and primary Keggin structure remained intact. The photocatalytic and sonocatalytic activity of the supported polyphosphotungstate was tested via degradation of different dyes in aqueous solutions. The POM-ZrO2 nanocomposite showed higher photocatalytic and sonocatalytic activity than pure polyoxometalate or pure ZrO2. 相似文献
7.
Abdul Aleem Jamali Bernd Witzigmann Rodica Morarescu Thomas Baumert Frank Träger Frank Hubenthal 《Applied Physics A: Materials Science & Processing》2013,110(4):743-749
In this contribution we present recent experimental and theoretical results on local near-field assisted laser ablation. Along these lines, we have generated sub-diffraction sized nanostructures on fused silica substrates, exploiting the local near fields of highly ordered triangular gold nanoparticle arrays generated by nanosphere lithography. After preparation, the nanoparticle arrays were irradiated with a single 35 fs long laser pulse with a central wavelength of λ=790 nm. The pulse energy was set to E=3.9 μJ, resulting in a fluence well below the ablation threshold of the fused silica substrates. In addition, 3D electromagnetic simulations using a finite integration technique in time domain have been performed. The simulations demonstrate that indeed the local field in the vicinity of the tips of the triangular nanoparticles overcome the ablation threshold and easily explain the generated nanostructures. Most importantly, the simulations show, that higher order modes contribute to the ablation process. These modes cause ablation along the side edges of the nanoparticles. Finally, we demonstrate, that the optical properties of the triangular nanoparticles, which can be tuned by their morphology, are crucial parameters for the generation of the ablation structures. 相似文献
8.
In part 1 of this series of two extensive overviews of multi-component polymerization case studies, we present mathematical modelling results with experimental confirmations. The case studies are from free-radical, bulk and/or solution polymerizations, covering the range from homo- to hexa-polymerization at both regular and elevated temperature levels, i.e., without and with possible depropagation steps. The model eventually tackles complex polymerization features, ranging from conversion-time histories to more esoteric multi-component composition and/or sequence length profiles. Part 2 of the series will describe more complicated situations with depropagation and composition control policies, all relying solely on a unique monomer/polymer database of physico-chemical properties and other characteristics, with no further parameter adjustment. These database items will be cited in tables in part 2 of the series. 相似文献
9.
Yaghoubi-berijani Marzieh Bahramian Bahram Zargari Solmaz 《Research on Chemical Intermediates》2020,46(1):197-213
Research on Chemical Intermediates - The bismuth oxybromide (BiOBr) photocatalyst was first synthesized via a simple co-precipitation method. To improve the visible light photocatalytic activity of... 相似文献
10.
Genetic algorithm (GA) and singular value decomposition (SVD) are deployed for the optimal design of both Gaussian membership
functions of antecedents and the vector of linear coefficients of consequents, respectively, of adaptive neurofuzzy inference
systems (ANFIS) networks that are used for fatigue life modelling and prediction of unidirectional GRP Composites. The aim
of such modelling is to show how the fatigue life varies with the variation of important parameters namely, maximum stress,
stress ratio, fiber angle. It is demonstrated that SVD can be effectively used to optimally find the vector of linear coefficients
of conclusion parts in ANFIS models and their Gaussian membership functions in premise parts are determined by GA. 相似文献