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671.
Natalya V. Likhanova Diego Guzmán-Lucero Eugenio A. Flores Paloma García Marco A. Domínguez-Aguilar Jorge Palomeque Rafael Martínez-Palou 《Molecular diversity》2010,14(4):777-787
Seventy five ionic liquids (ILs) were tested as a sequestering agent of sulfured compounds in natural gasoline (NG). Desulphurization
of NG was performed by means of liquid–liquid extraction method at room temperature and atmospheric pressure. Experimental
ILs containing imidazolium, pyridinium, and ammonium cations along with organic and inorganic anions were synthesized conventionally
and under microwave and sonochemical conditions. The effect of the molecular structure of ILs on the desulfurization efficiency
of NG with high sulfur content was evaluated. Analysis indicated that the anion type played a more important role than the
cation on the desulphurization process. ILs based on halogen–ferrates and halogen–aluminates exhibited the highest efficiency
in sulfur removal, and their efficiency is further improved when there is an excess of metallic salt in a ratio of at least
1:1.3 during the synthesis of the corresponding IL. An explanation for the ability of metallic ILs to remove sulfur-containing
compounds from natural gasoline based on the ratio of the ionic charge to the atomic radius is proposed. Furthermore, a method
to recover and reuse water-sensitive to halogenated precursors is described. 相似文献
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673.
Eugenio Costamagna 《Nonlinear dynamics》2018,93(1):119-132
This study is concerned with forced damped purely nonlinear oscillators and their behaviour at different excitation frequencies. First, their dynamics is considered numerically for the response determined in the vicinity of a backbone curve with the aim of detecting coexisting responses that have not been found analytically so far. Both the cases of low and high excitation amplitudes are investigated. Second, the angular excitation frequency is lowered significantly for different powers of nonlinearity, and the system’s behaviour is examined qualitatively, which has not been considered previously related to a general class of purely nonlinear oscillators. It is illustrated that the response at a low-valued angular excitation frequency has a form of bursting oscillations, consisting of fast oscillations around a slow flow. Finally, approximate analytical solutions are presented for the slow and fast flow for a general class of purely nonlinear oscillators. 相似文献
674.
C. Herz introduced in [Hr] some new spaces to study properties of functions. An Interesting account, with many applications, of some particular cases of the generalized Herz spaces is given in [BS]. In this paper we first identify the duals of the generalized Herz spaces. Then, we characterize their intermediate spaces when the complex method of interpolation for families of spaces Is used. Applications are given that show the bounded ness of many operators on the generalized Herz spaces. 相似文献
675.
Lourdes Santana Marta Teijeira Eugenio Uriarte 《Journal of heterocyclic chemistry》1999,36(1):293-295
(±)-trans-1-[2-(Hydroxymethyl)cyclopentylmethyl]uracil ( 1 ) was prepared in two steps and 56% yield from 2-hydroxymethylcyclopentylmethylamine (7) and 3-methoxy-2-propenoylisocyanate ( 6 ). Isocyanate 6 was prepared from methyl 3-methoxy-2-propenoate in four steps and 38% overall yield. 相似文献
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