No abstract

Using ionic liquid (IL) [C 2 MIM][PF 6 ] as an additive could remarkably improve the performance of the acetonitrile (CAN) process, which is the most widely used distillation process to produce 1,3-butadiene (1,3-BT). In this work, a rigorous simulation of a new IL process to produce 1,3-BT was carried out to evaluate the performance of IL additive on an industrial scale, using UNIFAC as the global thermodynamic model. Based on the simulation models, some key operation parameters, such as solvent ratio and reflux ratio, were determined by sensitivity analysis. Furthermore, a multi-objective optimization was proposed and performed considering both the energy consumption and environmental impact (green degree) of the new process. A nonlinear mathematical model was established to express this multi-objective optimization problem, which includes six decision variables and involves maximizing the green degree of the process, the purity and the recovery of 1,3-BT, and minimizing the energy consumption of the process. The optimization results showed that the energy consumption of the IL-containing process could be reduced by 22 % and that its green degree could be improved by 9.2 %.

No abstract

No abstract

No abstract

Multi‐phase DC/DC converter is widely used in fuel cell vehicles to adjust the voltage. Single phase mode of converter is adopted to increase efficiency when current ripple meets requirement. Therefore, it is necessary to commutate between different phases at low frequency, due to the temperature rising of each phase‐leg. However, narrow pulse current occurs during the phase commutation. Pulse current can cause variations in water and gas content inside the proton exchange membrane fuel cell (PEMFC), which is the driving force for degradation. To analyze the effect of low frequency narrow pulse current on fuel cell, an isothermal 1D‐PEM fuel cell model is presented to characterize the transient changes of these parameters: gas stoichiometry, relative humidity, water content and pressure difference. After comparing the influence on fuel cell of four types of pulse current, the results reveal that the 4 ms narrow pulse current cannot affect fuel cell lifetime, since no gas shortage occurred, the change of relative humidity and membrane water content are less than 1‰ and the pressure difference varies within specified range. Besides, the membrane lifetime reduces to 4,166 h as the width of narrow pulse current increased from 4 ms to 0.8 s.

The interaction between chloramphenicol (CHL) and neuroglobin (Ngb) has been investigated by using fluorescence, synchronous fluorescence, UV-Vis and circular dichroism (CD) spectroscopy. It has been found that CHL molecule can quench the intrinsic fluorescence of Ngb in a way of dynamic quenching mechanism, which was supported by UV-Vis spectral data. Their effective quenching constants (KSV) are2.2×104,2.6×104,and 3.1×104 L⋅mol−1at 298 K, 303 K, and 308 K, respectively. The enthalpy change (ΔH) and entropy change (ΔS) for this reaction are 26.42 kJ⋅mol−1and 171.7 J⋅K−1, respectively. It means that the hydrophobic interaction is the main intermolecular force of the interaction between CHL and Ngb. Synchronous fluorescence spectra showed that the microenvironment of tryptophan and tyrosine residues of Ngb has been changed slightly. The fluorescence quenching efficiency of CHL to tyrosine residues is a little bit more than that to tryptophan residues of Ngb. Furthermore, CD spectra indicated that CHL can induce the formation of α-helix of Ngb.

No abstract