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31.
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Syed Farooq Adil Mohamed E. Assal Mohammed Rafi Shaik Mufsir Kuniyil Azhar Hashmi Mujeeb Khan Aslam Khan Muhammad Nawaz Tahir Abdulrahman Al-Warthan Mohammed Rafiq H. Siddiqui 《应用有机金属化学》2020,34(8):e5718
Graphene–metal nanocomposites have been found to remarkably enhance the catalytic performance of metal nanoparticle-based catalysts. In continuation of our previous report, in which highly reduced graphene oxide (HRG)-based nanocomposites were synthesized and evaluated, we present nanocomposites of graphene oxide (GRO) and ZnO nanoparticle-doped MnCO3 ([ZnO–MnCO3/(1%)GRO]) synthesized via a facile, straightforward co-precipitation technique. Interestingly, it was noticed that the incorporation of GRO in the catalytic system could noticeably improve the catalytic efficiency compared to a catalyst (ZnO–MnCO3) without GRO, for aerial oxidation of benzyl alcohol (BzOH) employing O2 as a nature-friendly oxidant under base-free conditions. The impacts of various reaction factors were thoroughly explored to optimize reaction conditions using oxidation of BzOH to benzaldehyde (BzH) as a model substrate. The catalysts were characterized using X-ray diffraction, thermogravimetric analysis, Fourier transform infrared spectroscopy, field-emission scanning electron microscopy, Energy dispersive X-ray spectroscopy (EDX), Brunauer-Emmett-Teller (BET), and Raman spectroscopy. The (1%)ZnO–MnCO3/(1%)GRO exhibited significant specific activity (67 mmol.g−1.hr−1) with full convversion of BzOH and >99% BzH selectivity within just 6 min. The catalytic efficiency of the (1%)ZnO–MnCO3/(1%)GRO nanocomposite was significantly better than the (1%)ZnO–MnCO3/(1%)HRG and (1%)ZnO–MnCO3 catalysts, presumably due to the existence of oxygen-possessing groups on the GRO surface and as well as a very high surface area that could have been instrumental in uniformly dispersing the active sites of the catalyst, i.e., ZnO–MnCO3. Under optimum circumstances, various kinds of alcohols were selectively transformed to respective carbonyls with full convertibility over the (1%)ZnO–MnCO3/(1%)GRO catalyst. Furthermore, the highly effective (1%)ZnO–MnCO3/(1%)GRO catalyst could be successfully reused and recycled over five consecutive runs with a marginal reduction in its performance and selectivity. 相似文献
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Considering the Teichmüller space of a surface equipped with Thurston’s Lipschitz metric, we study geodesic segments whose endpoints have bounded combinatorics. We show that these geodesics are cobounded, and that the closest-point projection to these geodesics is strongly contracting. Consequently, these geodesics are stable. Our main tool is to show that one can get a good estimate for the Lipschitz distance by considering the length ratio of finitely many curves. 相似文献
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37.
Mohd.Rafi Segi Rahmat 《模糊系统与数学》2008,22(3)
In this paper, we obtain some new fixed point theorems in fuzzy-Banach spaces by considering the t-norms of h-type and a linear mapping of weakly demicompact. 相似文献
38.
M. Rafi M. Latif S. Mahmood I. A. Khan M. R. Husain 《Zeitschrift für Physik D Atoms, Molecules and Clusters》1993,25(2):153-156
The absorption spectra of Bi2 molecule has been obtained in the region 3166–3380 Å in the second order of a 3.4 m Ebert Spectrograph with a reciprocal dispersion of 2.6 Å/mm. The bands obtained are found to belong to two new systems named G-X and J-X. Vibrational analysis is performed and computer methods have been used to determine the molecular constants. 相似文献
39.
Peel Christopher S. Fang Xiao Ahmad S. Rafi 《Applied Physics A: Materials Science & Processing》2011,103(4):1131-1138
This paper presents an analysis of the rate of bubble expansion and an estimate of maximum bubble diameter and bubble lifetime
prior to collapse. Such data are needed for the optimization of system parameters for elemental analysis in water by laser-induced
breakdown spectroscopy (LIBS). Two techniques were used for this study: pump-probe beam deflection and high-speed photography.
Plasma in the water bulk was generated by a focussed laser pulse with energy of 140 mJ and pulse duration of 10 ns, operating
at the fundamental Nd:YAG laser wavelength (1064 nm). Reasonable agreement on the value of maximum bubble diameter was obtained
between the photographic and probe beam deflection results. Reasonable agreement for the total duration of the oscillating
cavitation bubble was also obtained for the two techniques, with a mean value of ∼800 μs. A comparison between empirical results
and predictions based on the Rayleigh equation is also presented. 相似文献
40.
We show that both Teichmüller space (with the Teichmüller metric) and the mapping class group (with a word metric) have geodesic divergence that is intermediate between the linear rate of flat spaces and the exponential rate of hyperbolic spaces. For every two geodesic rays in Teichmüller space, we find that their divergence is at most quadratic. Furthermore, this estimate is shown to be sharp via examples of pairs of rays with exactly quadratic divergence. The same statements are true for geodesic rays in the mapping class group. We explicitly describe efficient paths “near infinity” in both spaces. 相似文献