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51.
Tetrachlorosilane was found to be a mild as well as selective catalyst for dithioacetalization of the carbonyl compounds. 相似文献
52.
A k-regular bipartite graph is said to be 2-factor hamiltonian if each of its 2-factor is hamiltonian. It is well known that if a k-regular bipartite graph is 2-factor hamiltonian, then k?Q3. In this paper, we give a new proof of this fact. 相似文献
53.
Rafa? Janus Piotr Natkański Anna Wach Marek Drozdek Zofia Piwowarska Pegie Cool Piotr Ku?trowski 《Journal of Thermal Analysis and Calorimetry》2012,110(1):119-125
Thermogravimetry, diffuse reflectance infrared Fourier transform spectroscopy, and X-ray photoelectron spectroscopy (XPS) were used for the studying of thermally induced structural changes of polyacrylonitrile (PAN) deposited on the surface of SBA-15 type mesoporous silica. Polymer was introduced onto the support by the precipitation polymerization of acrylonitrile in aqueous suspension of SBA-15. Low temperature transformation (to 723?K) of the deposited PAN was analyzed. It was found that at about 523?K, exothermic cyclization of polymer chains to the so-called ladder form of PAN occurred. However, the total cyclization of PAN required higher carbonization temperatures, at which gradual dehydrogenation followed by graphitization was initiated. XPS revealed that the cyclic form of PAN and a relatively large amount of carbonyl species, formed during the carbonization of the PAN/SBA-15 composite at 623?K, were responsible for the high sorption capacity in the methyl?Cethyl ketone (MEK) vapor elimination. The efficiency in the MEK adsorption was also influenced by the content of PAN-derived carbon deposited on the SBA-15 surface. 相似文献
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This paper proposes a switchable wavelength fiber laser (SWFL) based on an arrayed waveguide grating (AWG) and a gain-saturated
reflective semiconductor optical amplifier (RSOA). The SWFL was experimentally implemented in the C- and L-bands. In order
to achieve narrow-linewidth oscillation, the SWFL was driven by bidirectional injection-locked RSOAs. The RSOA was operated
in the gain-saturated region, using gain compression properties to obtain uniform power over a wide bandwidth. Based on this
configuration, we obtained 40 C-band international telecommunication unit (ITU) wavelengths with 100-GHz channel spacing.
The SWFL displayed a narrow 3-dB bandwidth (<0.06 nm), a high and uniform peak power (P
max > 0.22 dB, ΔP
max < 0.26 dB), and a high and uniform side mode suppression ratio (SMSR > 66 dB, ΔSMSR < 1 dB). The peak-power and wavelength
stabilities were ±0.24 dB and ±0.01 nm, respectively, at room temperature over a 1 h period. 相似文献
57.
Xiang Hao Cuifang Kuang Yanghui Li Xu Liu Yulong Ku Yunshan Jiang 《Optics Communications》2012,285(20):4130-4133
By increasing the hydrophilicity of microsphere, the evaporation of liquid around the microsphere will be evidently eliminated, so that the droplet can remain stable, and it is more feasible to introduce the liquid immersed MMM system in practical utilizations that require long-time observation. Compared with the non-immersed one, the liquid immersed MMM system performs better in various aspects, and it is convenient to choose microspheres on a wider scale. 相似文献
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This paper deals with the problem of active vibration suppression using the concept of delayed resonator (DR) absorber with acceleration feedback. A complete dynamic analysis of DR and its coupling with a single degree of freedom mechanical system are performed. Due to the presence of a delay in the acceleration feedback, the dynamics of the resonator itself, as well as the dynamics of combined system are of ‘neutral’ character. On this system, spectral methods are applied to perform a complete stability analysis. Particularly, the method of cluster treatment of characteristic roots is used to determine stability boundaries in the space of the resonator parameters. Based on this analysis, a methodology to select the resonator parameters is proposed in order to guarantee desirable suppression characteristics and to provide safe stability margins. An example case study is included to demonstrate these analytical results. 相似文献