[en] Highlights: • The PANI/Fe"3"+ films were synthesized by CV on stainless steel wire mesh. • The growth rate of PANI/Fe"3"+ films were greatly increased. • The PANI/Fe"3"+ films show a larger specific capacitance and lower resistance. • The relationship between electrochemical properties of a serious of transition metal ions doped PANI and the ratio of electronic affinity and ionic radius (Ea/r) has also been researched. - Abstract: H"+ and Fe"3"+ ions co–doped polyaniline were synthesized by cyclic voltammetry onto the stainless steel mesh with various concentration of ferric chloride (FeCl_3·6H2O) in electrolyte. The structure and morphology of PANI and PANI/Fe"3"+ films were characterized by Fourier transform infrared (FT–IR), X-ray diffraction (XRD), Scanning electron microscopy (SEM), Energy dispersive X-ray spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS) techniques. The electrochemical properties of PANI and PANI/Fe"3"+ films were investigated by cyclic voltammetry, galvanostatic charge–discharge test and electrochemical impedance spectroscopy (EIS) in 0.5 mol L"−"1 H2SO4 electrolyte in three–electrode system. The PANI/0.2 M Fe"3"+ film shows a larger specific capacitance of 602 F g"−"1 at a current density of 3 mA/cm"2 and lower resistance compared with the pure PANI film. The relationship between electrochemical properties of a serious of transition metal ions doped PANI/M"n"+ (M"n"+ = Mn"2"+, Co"2"+, Ni"2"+, Cu"2"+, Zn"2"+ and Fe"3"+) films and the ratio of electronic affinity and ionic radius (Ea/r) has also been researched

[en] Highlights: • Maximum isolator pressure ratio confines the operating boundary of scramjet. • There exists minimum freestream Mach number at each equivalent ratio. • The minimum freestream Mach number increases with equivalence ratio. • The minimum freestream Mach number increases with inlet compression ratio. • The scramjet operating boundary can be expanded by adding a divergent section. The maximum pressure ratio of the isolator is important for studying the operating boundary of the dual mode scramjet. In this paper, the pressure rise mechanism of the dual mode scramjet engine and the characteristic of the isolator maximum pressure rise are analyzed. The operating range and performance of scramjet under the pressure rise limit are investigated using the constant cross-sectional area combustor. The maximum pressure ratio of the isolator confines the back pressure from the combustor so that the scramjet engine has a minimum freestream Mach number of each equivalence ratio. When the freestream Mach number is smaller than the minimum freestream Mach number, an expansion section may be arranged between the combustor and the isolator to balance the pressure of the combustor and that of the isolator. The expression of the minimum freestream Mach number is derived and it is found that the minimum freestream Mach number of the dual mode scramjet in both modes increases with the increase of equivalence ratio and compression ratio of the inlet. A variable divergent section is suggested to balance the pressure under different freestream Mach numbers and equivalence ratios.

[en] The effects of solution treatment on microstructure transformation and tensile properties of 7136 aluminum alloys were investigated by means of scanning electron microscopy, electron backscatter diffraction, differential scanning calorimeter, x-ray diffraction and tensile test, electrochemical evaluations, exfoliation corrosion tests, respectively. The results indicate that solution treatment had a significant effect on the microstructure transformation and tensile properties. Soluble constituents of 7136 aluminum alloys were more likely to form the η(MgZn₂) phase rather than the S(Al₂CuMg) phase. With increasing the solution temperature, the η phase was re-dissolved into the α(Al) matrix gradually. After solution treatment of 475 °C/1 h, the η phase was completely dissolved into the matrix, with insoluble Fe-rich phases remained. The dissolution of η phase would increase the strength and the corrosion resistance of the alloys. When continuing to increase the solution temperature, the recrystallized fraction increased obviously, resulting in the decrease in the strength and the corrosion resistance. Consequently, the strength and the corrosion resistance of the alloys increased firstly and then decreased with the increase in solution temperature. After solution treatment of 475 °C/1 h, the tensile strength and yield strength of the aged alloy reached their peaks, 738  and 715 MPa, respectively. The elongation of the alloy solution treated at 475 °C/1 h reached 11.2%, and its exfoliation corrosion rating got EB level. Furthermore, after the double-stage solution treatment of 450 °C/1 h + 475 °C/1 h, the recrystallized fraction decreased, resulting in a slight increase to 12.6% of the elongation, a slight increase in the corrosion resistance and a slight decrease in the strength.

[en] Highlights: ► The PANI/Ni²⁺ films was synthesized by CV on stainless steel substrates. ► The growth rate of PANI/Ni²⁺ films was greatly increased. ► The PANI/Ni²⁺ films show a larger specific capacitance and lower resistance. -- Abstract: Polyaniline (PANI) films doped with Ni²⁺ (PANI/Ni²⁺) were synthesized by cyclic voltammetry (CV) on stainless steel (SS) substrates in 0.2 mol/L aniline (An) and 0.5 mol/L sulfuric acid (H₂SO₄) electrolyte with various concentration of nickel sulfate (NiSO₄). The structure and morphology of PANI/Ni²⁺ films were characterized by Fourier transform infrared (FTIR), X-ray diffraction (XRD), Scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS) techniques. The electrochemical properties of PANI/Ni²⁺ films were investigated by cyclic voltammetry, galvanostatic charge–discharge test and electrochemical impedance spectroscopy (EIS) in 0.5 mol/L H₂SO₄ electrolyte in three-electrode system. The results suggest that the growth rate of PANI was greatly increased, which may arise from the interactions between PANI chain and Ni²⁺. The PANI/Ni²⁺ films show a larger specific capacitance of 658.3 F/g at a current density of 5 mA/cm² and lower resistance compared with the pure PANI film. The results indicate that the PANI/Ni²⁺ films are promising material for supercapacitors

[en] Highlights: • Simulated devices are built to simulate the tidal cycle. • Tidal cycle has significant effect on the release of DOM, N and P. • Tidal cycle changes the microbial richness and diversity. • Microbial diversity explains the mechanism of nutrient release. • A model is introduced to predict the short-term release of N and P. Tide drives salt mixing processes, erosion, deposition, and nutrient circulation in sediments, which is critical to the estuarine systems. This study aims to investigate the effects of tidal cycle intensity on sediment dissolved organic matter (DOM), nitrogen and phosphorus release. In this study, the effects of tide are investigated by simulating different intensity of tidal disturbance with tidal simulator devices. The microbial community changes under different tidal cycle are disclosed to explain the mechanism of nutrient release. In addition, the short-term release of nitrogen and phosphorus under simulated tidal cycle is predicted by stepwise regression method. Results show that the higher the tidal cycle intensity, the stronger the DOM mineralization in sediments and diffusion into overlying water, leading to a sustained increase of fluorescence intensity in DOM. Besides, the tidal disturbance promotes the NH₄⁺-N and NO₃⁻-N release and the tidal disturbance is helpful for ammonification. While the greater the tidal intensity, the lower the NO₃⁻-N release. Content of released total phosphorus (TP) maintains at a low level and fluctuates over time under different simulated tidal intensity. In addition, tidal cycle greatly changes the microbial richness and diversity. Gammaproteobactere has the ability of denitrification and can reduce nitrate to nitrite. Besides, tidal environment greatly affects the abundance of Marinobacter which can enhance the N, P, and C migration transformation ability. The research on microbial community further explains the mechanism of nutrient release. The model of nitrogen and phosphorus release contributes to providing basic data for predicting the short-term release of nutrients under different simulated tidal intensity.

[en] In this study, a multi-level-factorial risk-inference-based possibilistic-probabilistic programming (MRPP) method is proposed for supporting water quality management under multiple uncertainties. The MRPP method can handle uncertainties expressed as fuzzy-random-boundary intervals, probability distributions, and interval numbers, and analyze the effects of uncertainties as well as their interactions on modeling outputs. It is applied to plan water quality management in the Xiangxihe watershed. Results reveal that a lower probability of satisfying the objective function (θ) as well as a higher probability of violating environmental constraints (q_i) would correspond to a higher system benefit with an increased risk of violating system feasibility. Chemical plants are the major contributors to biological oxygen demand (BOD) and total phosphorus (TP) discharges; total nitrogen (TN) would be mainly discharged by crop farming. It is also discovered that optimistic decision makers should pay more attention to the interactions between chemical plant and water supply, while decision makers who possess a risk-averse attitude would focus on the interactive effect of q_i and benefit of water supply. The findings can help enhance the model’s applicability and identify a suitable water quality management policy for environmental sustainability according to the practical situations.