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《Arabian Journal of Chemistry》2022,15(8):104012
A catalyst based on MoO3 was synthesized by a simple and fast pilot-scale combustion reaction method and applied to the conversion of soybean oil to biodiesel via transesterification. For that, the statistical analysis of the catalyst amount and temperature, factors that influence the process, was evaluated by means of central composite design 22. MoO3 was characterized in terms of structure by X-ray diffraction (XRD), textural characterization Brunauer-Emmett-Teller (BET), density by helium pycnometry (DE), particle size analysis (DG) and acidity tests by temperature-programmed desorption of ammonia (NH3-TPD), chemical analysis by X-ray fluorescence (EDX), morphology by scanning electron microscopy (SEM) and catalytic properties. The transesterification products were characterized by gas chromatography (GC), acidity index (AI) and kinematic viscosity (KV). The results indicate the catalyst formation with a surface area of 1.36 m2g?1, and density of 4.5 g/cm3 which consists of a single crystalline phase of orthorhombic configuration, with total NH3 acidity of 33.61 μ.mol/g. Morphological characterization revealed that the catalyst is formed by irregular plates of various sizes and shapes, with a wide sizes range of agglomerated particles. In the soybean oil transesterification reactions, the catalyst was active showing 96.9% conversion to ethyl esters. The experimental design was meaningful and predictive, with a reliability level of 95%. The statistical analysis identified temperature as a significant variable for the adopted planning. To conclude, a new single-phase catalyst (α-MoO3) has been developed and successfully applied to the biodiesel Synthesis from soybean oil. These results have a positive and promising impact for biodiesel production by transesterification of soybean oil against ethanol. 相似文献
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Theoretical study on the mechanism for the excited-state double proton transfer process of an asymmetric Schiff base ligand 下载免费PDF全文
Zhengran Wang 《中国物理 B》2022,31(4):48202-048202
Excited-state double proton transfer (ESDPT) in the 1-[(2-hydroxy-3-methoxy-benzylidene)-hydrazonomethyl]-naphthalen-2-ol (HYDRAVH2) ligand was studied by the density functional theory and time-dependent density functional theory method. The analysis of frontier molecular orbitals, infrared spectra, and non-covalent interactions have cross-validated that the asymmetric structure has an influence on the proton transfer, which makes the proton transfer ability of the two hydrogen protons different. The potential energy surfaces in both S0 and S1 states were scanned with varying O-H bond lengths. The results of potential energy surface analysis adequately proved that the HYDRAVH2 can undergo the ESDPT process in the S1 state and the double proton transfer process is a stepwise proton transfer mechanism. Our work can pave the way towards the design and synthesis of new molecules. 相似文献
4.
Majorana fermions induced fast-and slow-light in a hybrid semiconducting nanowire/superconductor device 下载免费PDF全文
We investigate theoretically Rabi-like splitting and Fano resonance in absorption spectra of quantum dots(QDs)based on a hybrid QD-semiconducting nanowire/superconductor(SNW/SC)device mediated by Majorana fermions(MFs).Under the condition of pump on-resonance and off-resonance,the absorption spectrum experiences the conversion from Fano resonance to Rabi-like splitting in different parametric regimes.In addition,the Fano resonances are accompanied by the rapid normal phase dispersion,which will indicate the coherent optical propagation.The results indicate that the group velocity index is tunable with controlling the interaction between the QD and MFs,which can reach the conversion between the fast-and slow-light.Fano resonance will be another method to detect MFs and our research may indicate prospective applications in quantum information processing based on the hybrid QD-SNW/SC devices. 相似文献
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Here we propose and analyze a mathematical model that aims to describe the marble sulphation process occurring in a given material. The model accounts for rugosity as well as for damaging effects. This model is characterized by some technical difficulties that seem hard to overcome from a theoretical viewpoint. Therefore, we introduce some physically reasonable modifications in order to establish the existence of a suitable notion of solution on a given time interval. Numerical simulations are presented and discussed, also in view of further research. 相似文献
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Baoquan Zhou Daqing Jiang Bingtao Han Tasawar Hayat 《Mathematical Methods in the Applied Sciences》2022,45(1):423-455
Considering the effect of stochasticity including white noise and colored noise, this paper aims to study a hybrid stochastic cholera epidemic model with waning vaccine-induced immunity and nonlinear telegraph perturbations. First, we derive a critical value related to the basic reproduction number of the deterministic model. The key aim of this paper is to generalize the θ-stochastic criterion method proposed by the recent work (Han et al. in Chaos Solit Fract 140:110238, 2020) to eliminate nonlinear telegraph perturbations. Next, via constructing several θ-stochastic Lyapunov functions and using the generalized method, we further prove that the stochastic model have a unique ergodic stationary distribution under . Results show that the prevention and control of cholera epidemic depend on low transmission rate and small telegraph perturbations. Finally, the corresponding numerical simulations are performed to illustrate our analytical results and a practical application on the Somalia cholera outbreak is shown at the end of this paper. 相似文献
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Dariusz Marek Adam Domaski Joanna Domaska Jakub Szygua Tadeusz Czachrski Jerzy Klamka 《Entropy (Basel, Switzerland)》2021,23(5)
In this article, a way to employ the diffusion approximation to model interplay between TCP and UDP flows is presented. In order to control traffic congestion, an environment of IP routers applying AQM (Active Queue Management) algorithms has been introduced. Furthermore, the impact of the fractional controller and its parameters on the transport protocols is investigated. The controller has been elaborated in accordance with the control theory. The TCP and UDP flows are transmitted simultaneously and are mutually independent. Only the TCP is controlled by the AQM algorithm. Our diffusion model allows a single TCP or UDP flow to start or end at any time, which distinguishes it from those previously described in the literature. 相似文献
10.
利用平面动力系统方法的分支理论,研究了Boussinesq方程,通过对Boussinesq方程进行行波变换,得到了相应行波系统的首次积分和平衡点,给出了不同参数条件下的相图,证实了Boussinesq方程存在孤立波解和周期波解。 相似文献