Tribological behavior studies of chemically bonded phosphate ceramic coatings reinforced with modified multi-walled carbon nanotubes (MWCNTs)

To improve the wear resistance of the chemically bonded phosphate ceramic coatings, MWCNTs are selected as the reinforcement after the modification. The high temperature wear experiment is carried out to investigate the wear behavior of the coatings with different temperatures. The results suggest that, when the temperature is below 500℃, MWCNTs can decrease friction coefficient, and the lowest friction coefficient is about 0.28, but MWCNTs lose the lubricant function at 500℃ and the friction coefficient keeps at the level of ~ 0.68. In addition, the wear resistance of coatings is improved with the introduction of MWCNTs at 100℃ and 300℃ (the wear rate is below 15X10^-3mm³/Nm), but keeps similar level at 500℃ (the wear rate is ~ 22 × 10⁻³mm³/Nm). Besides, the wear mechanism of the coatings reinforced by MWCNTs is also investigated based on the wear behavior and microstructural characterizations. MWCNTs improve the fracture toughness by preventing the crack generation and forming the bridge when crack occurs, which leads to smooth wear tracks and good wear resistance of coatings. The coatings with MWCNTs achieve poor wear resistance at 500℃ because MWCNTs lose their strength and resistance to fatigue by oxidizing.     

Relaxor behavior and energy storage density induced by B-sites substitutions in (Ca0.28Ba0.72)2.1Na0.8Nb5O15 Tungsten bronze ceramics

Lead-free relaxor ferroelectrics (Ca_0.28Ba_0.72)_2.1Na_0.8Nb_5-xSb_xO₁₅ (CBNNS) and (Ca_0.28Ba_0.72)_2.1Na_0.8Nb_5-yTa_yO₁₅ (CBNNT) with tungsten bronze structure were fabricated via solid-state reactions. The obtained CBNNS and CBNNT ceramics showed different dielectric behaviors. Only the CBNNS ceramics revealed an intensified diffusion and relaxor-like characteristics, which could be verified by the modified Curie–Weiss law. The relaxor behaviors in CBNNS were attributed to the radii difference between Sb⁵⁺ and Nb⁵⁺ ions co-occupying in B-sites. For the substitution of Nb⁵⁺ by Sb⁵⁺ in CBNNS ceramics, the change from macroscopic polarization to local polarization could also give rise to the obvious relaxor behavior. The Raman spectra verified a larger off-centering of the cation and a higher distortion degree for BO₆ octahedron in the ab plane for CBNNS ceramics when compared with those of CBNNT. In addition, the ferroelectric properties of CBNNS ceramics further indicated the relaxor ferroelectric nature, and also confirmed that the relaxor behavior helped to improve the energy-storage performance.     

浮世绘《水浒人物》的“中国想象”——解析江户日本浮世绘画师歌川国芳的中国人物样式

日本浮世绘是诞生于江户时期市民文化下的一种民俗画形式。随着明清时期《水浒传》等文学作品传入日本,并在日本广泛传播,浮世绘画师开始对中国古典小说中的人物进行绘画创作。其中以歌川国芳为首,根据文学作品《水浒传》一百零八梁山好汉创作的《水浒人物英雄图》,引起了强烈反响。其人物样式在还原中国味道的同时,也透露出浓烈的日本风格。文章从文学形象的内涵误解、日本本土英雄范式的移植,及本土化创作这三方面解析,探究影响歌川国芳所绘制水浒人物样式的重要因素,并归纳出明清时期中国文化输出对日本所产生的影响。     

Influence of aluminum phosphate on the tribocorrosion performance of chemically bonded phosphate ceramic coatings

In this study, chemically bonded phosphate ceramic coatings (CBPCCs) with different contents of aluminum phosphate (AP) are prepared on stainless steel (AISI 304L). Differential scanning calorimetry, X-ray diffraction, contact angle test, and a tribocorrosion experiment are carried out to clarify the role of AP in the tribocorrosion performance of CBPCCs. The results show that, with the increase in the AP content, the enthalpy of curing increases because of the greater formation of the bonding phase AlPO₄. Both in static corrosion and in tribocorrosion, the corrosion current density of CBPCCs achieves the lowest value when the weight ratio of AP to polytetrafluoroethylene is about 0.78. Additionally, the influence mechanism of AP on tribocorrosion is clarified. AlPO₄ from the reaction between AP and Al₂O₃ has excellent mechanical properties and can enhance the wear resistance of CBPCCs by reducing the mechanical wear and the increased wear due to corrosion. The alumina particles wrapped by AlPO₄ can form a dense and smooth surface and change the direction of electrolyte propagation, which leads to the increase in the tribocorrosion resistance of CBPCCs.     

Simultaneous degradation of RhB and reduction of Cr(VI) by MIL-53(Fe)/Polyaniline (PANI) with the mediation of organic acid

MIL-53(Fe)/polyaniline (PANI) composite was prepared by in situ depositing PANI on the surface of MIL-53(Fe) and their catalytic performances on the simultaneous removal of RhB and Cr(VI) were investigated. The elimination efficiency of both RhB and Cr(VI) reached more than 98% under pH=2 where hydrochloric acid and citric acid were used to adjust the pH. The results indicated that MIL-53(Fe)/PANI revealed an obvious pH response to the degradation of RhB, while citric acid promoted the Cr(VI) photoreduction. UV-Vis spectra, EIS, and photocurrent response experiments showed that MIL-53(Fe)/PANI had a better light response and carrier migration ability than MIL-53(Fe). The transient absorption spectra also exhibited that the lifetimes of photo-generated carriers were prolonged after the conductive polymer deposition on the MIL-53(Fe) surface. Scavenger experiments demonstrated that the main active species were ·O₂^- and OH. Combined with activity evaluation results, and the possible photocatalytic mechanism of MIL-53(Fe)/PANI on RhB oxidation and Cr(VI) reduction was proposed. The addition of conductive polymer can effectively improve the light response of the catalyst under acidic conditions, and meanwhile citric acid also provided a new mediation for the synergistic degradation of multiple pollutants. Good activity and stability of the catalysts made the scale-up purification of acid water feasible under UV-Vis light.     

Quantitatively exploring the relationship between eye movement and driving behavior under the effect of different complex diagrammatic guide signs

Complex diagrammatic guide signs (DGSs) are widely used. To study the influence of DGSs with different complexities on drivers’ cognition, four types     

Techno-economic analysis of hydrogen energy for renewable energy power smoothing

With the increasing proportion of renewable energy (mainly wind power and photovoltaic) connected to the grid, the fluctuation of renewable energy power brings great challenges to the safe and reliable operation of power grid. As a clean, low-carbon secondary energy, hydrogen energy is applied in renewable energy (mainly wind power and photovoltaic) grid-connected power smoothing, which opens up a new way of coupling hydrogen storage energy with renewable energy. This paper focuses on the optimization of capacity of electrolyzers and fuel cells and the analysis of system economy in the process of power output smoothing of wind/photovoltaic coupled hydrogen energy grid-connected system. Based on the complementary characteristics of particle swarm optimization (PSO) and chemical reaction optimization algorithm (CROA), a particle swarm optimization-chemical reaction optimization algorithm (PSO-CROA) are proposed. Aiming at maximizing system profit, the capacity of electrolyzers and fuel cells are constrained by wind power fluctuation, and considering environmental benefits, government subsidies and time value of funds, the objective function and its constraints are established. According to the simulation analysis, by comparing the calculated results with PSO and CROA, it shows that PSO-CROA effectively evaluates the economy of the system, and optimizes the optimal capacity of the electrolyzers and fuel cells. The conclusion of this paper is of great significance for the application of hydrogen energy storage in the evaluation of power smoothness and economy of renewable energy grid connection and the calculation of economic allocation of hydrogen energy storage capacity.     

复合蛋白酶水解黑豆粕制备多肽的工艺优化

为充分利用黑豆粕中的蛋白质资源,研究了复合蛋白酶水解黑豆粕制备多肽的工艺路线。从蛋白酶的筛选入手,考察了不同蛋白酶对黑豆粕水解效果的差异,并通过复配比例优化了最佳复合蛋白酶的组成。采用单因素试验及响应面试验确定了复合蛋白酶水解黑豆粕的最佳工艺条件。结果表明:最佳复合蛋白酶为胰蛋白酶、碱性蛋白酶与桔青霉蛋白酶按酶活比1∶3∶2复配;最佳工艺条件为加酶量5 670 U/g,底物蛋白质量浓度40 g/L,pH 9.55,水解温度50℃,水解时间6 h。在优化的工艺条件下水解黑豆粕,多肽得率可以达到82.44%。水解液中多肽的相对分子质量均在7.8 kDa以下,大部分多肽的相对分子质量小于3.3 kDa;多肽基本上保持了黑豆粕蛋白的氨基酸组成,具有较高的营养价值。     

井下通风、排水及压缩空气设备选型设计

依据井下通风方式及瓦斯含量对井下通风设备进行了选型设计,给出了进行反风时的通风机工作特性以及通风机的电控形式;对井下排水设备和压缩空气设备进行了选型设计。井下工程实践表明,所选用的设备可满足矿井的正常生产需要。