Low-temperature constrained sintering of YSZ electrolyte with Bi2O3 sintering sacrificial layer for anode-supported solid oxide fuel cells

Solid oxide fuel cells (SOFCs) have strong potential for next-generation energy conversion systems. However, their high processing temperature due to multi-layer ceramic components has been a major challenge for commercialization. In particular, the constrained sintering effect due to the rigid substrate in the fabrication process is a main reason to increase the sintering temperature of ceramic electrolyte. Herein, we develop a bi-layer sintering method composed of a Bi₂O₃ sintering sacrificial layer and YSZ main electrolyte layer to effectively lower the sintering temperature of the YSZ electrolyte even under the constrained sintering conditions. The Bi₂O₃ sintering functional layer applied on the YSZ electrolyte is designed to facilitate the densification of YSZ electrolyte at the significantly lowered sintering temperature and is removed after the sintering process to prevent the detrimental effects of residual sintering aids. Subsequent sublimation of Bi₂O₃ was confirmed after the sintering process and a dense YSZ monolayer was formed as a result of the sintering functional layer-assisted sintering process. The sintering behavior of the Bi₂O₃/YSZ bi-layer system was systematically analyzed, and material properties including the microstructure, crystallinity, and ionic conductivity were analyzed. The developed bi-layer sintered YSZ electrolyte was employed to fabricate anode-supported SOFCs, and a cell performance comparable to a conventional high temperature sintered (1400 °C) YSZ electrolyte was successfully demonstrated with significantly reduced sintering temperature (<1200 °C).     

Effect of sintering conditions on structural and morphological properties of Y- and Co-doped BaZrO3 proton conductors

BaZrO₃-based materials doped with a trivalent cation have excellent chemical stability and relatively high proton conductivity which makes them potential proton conducting oxide materials for various electrochemical device applications such as hydrogen processing, high-temperature electrolysis, and solid electrolyte in fuel cells. However, BaZrO₃ showed poor sinterability, requiring high sintering temperatures (1700–2100 °C) with longtime sintering (20–100 h) to achieve the desired microstructure and grain growth. This sintering problem can be solved by slightly doping BaZrO₃ with a sintering aid element. Therefore, in this study, two different zirconate proton conductors: BaZr_0·9Y_0·1O_3-α (BZY) and BaZr_0·955Y_0·03Co_0·015O_3-α (BZYC) were sintered in an air atmosphere and an oxygen atmosphere for 20 h in the temperature range of 1500–1640 °C. The sinterability was evaluated by analyzing the XRD diffraction patterns, lattice constant, lattice strain, crystallite size, relative density, open porosity, closed porosity, surface morphology, grain size, and grain boundary distribution, using the XRD, SEM, EDX, and Archimedes density measurement methods. It is concluded that in an oxygen atmosphere, sintering aid Co not only improves the relative density but also produces highly dense fine particles with clear grain boundaries which are promising for electrochemical hydrogen device applications.     

Effect of sintering aids on the densification and electrical properties of SiO2 –containing Ce0.8Sm0.2O1.9 ceramic

In this work, five different metal-oxide additives (metal?=?Ba, Co, Fe, Li, and Mn) were examined as sintering aids and SiO₂ impurity scavengers for Ce_0.8Sm_0.2O_1.9 (SDC). 2?mol% additives were loaded into the SDC with ～150?ppm (moderately impure) and ～2000?ppm (highly impure) SiO₂. Ba-, Co-, Fe- and Mn-oxides showed comparative sintering-aid effect on both moderately- and highly-impure SDC specimens, but the sintering-assisting effect of Li-oxide was completely neutralized in highly impure SDC. Regarding electrical property, the deleterious effect of 2000?ppm SiO₂ impurity on the grain-boundary conduction of SDC can be effectively alleviated by adding Ba-, Co-, Fe-, or Mn-oxides. Microstructure analysis revealed that Ba-oxide reacted directly with SiO₂ and consequently enhanced grain-boundary conduction. By contrast, with the addition of Co-, Fe-, and Mn-oxides, the improved grain-boundary conductions of impure SDC were related to the scavenging reactions between Si, Ca (another original impurity) and Sm components.     

Invasion and Defense Interactions between Enzyme‐Active Liquid Coacervate Protocells and Living Cells

The design and construction of mutual interaction models between artificial microsystems and living cells have the potential to open a wide range of novel applications in biomedical and biomimetic technologies. In this study, an artificial form of invasion‐defense mutual interactions is established in a community of glucose oxidase (GOx)‐containing liquid coacervate microdroplets and living cells, which interact via enzyme‐mediated reactive oxygen species (ROS) damage. The enzyme‐containing coacervate microdroplets, formed via liquid–liquid phase separation, act as invader protocells to electrostatically bind with the host HepG2 cell, resulting in assimilation. Subsequently, the glucose oxidation in the liquid coacervates initiates the generation of H₂O₂, which serves as an ROS resource to block cell proliferation. As a defense strategy, introduction of catalase (CAT) into the host cells is exploited to resist the ROS damage. CAT‐mediated decomposition of H₂O₂ leads to the ROS scavenging and results in the recovery of cell viability. The results obtained in the current study highlight the remarkable opportunities for the development of mutual interacting communities on the interface of artificial protocells/living cells. They also provide a new approach for engineering cellular behaviors through exploiting artificial nonliving microsystems.     

基于互信息和PID神经网络的SCR脱硝扰动补偿控制

针对火电厂选择性催化还原(Selective Catalytic Reduction，SCR)烟气脱硝系统机理复杂，工况变化时呈现的不确定性、强扰动等特点，提出了一种基于互信息和PID神经网络的SCR烟气脱硝扰动补偿控制方法。利用PID前向神经网络的学习性能逼近被控对象的逆构成扰动观测器对系统进行反馈补偿，以达到超前消除系统扰动的目的。选取观测扰动和系统扰动的互信息为目标函数，采用改进的帝国竞争算法实现PID神经网络权值的优化调整。设计鲁棒PID控制器来进一步克服被控对象存在的不确定性。仿真实验表明，该方法具有突出的抗干扰能力和较好的鲁棒性，控制品质优于常规的PID控制。     

Role of MgO on densification and mechanical properties in spark plasma sintered Os0.9Re0.1B2 ceramic

To promote the densification and therefore the mechanical properties of boride-based ceramics, MgO was added as sintering aid into Os_0.9Re_0.1B₂ powders for densification by using spark plasma sintering (SPS). The Os_0.9Re_0.1B₂ powders were synthesized by mechanochemical method from powder mixture of Os, Re and amorphous B. The role of MgO on densification, phase composition, microstructure and mechanical properties (hardness, fracture toughness and wear behavior) were studied by using X-ray diffraction (XRD), scanning electron microscope (SEM) with energy-dispersive spectroscopy (EDS), micro indentation and ball-on-disk tribometer. The results show that, with the introduction of MgO as sintering aid, the relative density of the Os_0.9Re_0.1B₂ ceramic samples increased. When the MgO content reached 9 wt%, the as-sintered sample is almost fully dense. No obvious regularity was found from the samples with the addition of different content of MgO. Vickers hardness values of the samples with 0, 3 wt% and 9 wt% MgO are found to be very close with each other within the experimental error (~30 GPa), while the sample with the addition of 6 wt% MgO exhibits the highest hardness of ~35 GPa. The fracture toughness of the samples is decreased slightly with the addition of MgO. The friction coefficient and wear rate of the sample with the addition of 6 wt% MgO was also found to be the lowest among all samples, which indicate best wear resistance. As a whole, with the addition content of 6 wt% MgO, the Os_0.9Re_0.1B₂ ceramic sample performs relatively excellent mechanical properties among four groups of samples.     

某校化工院一级学生实验室急救知识调查干预

了解化学与化工院大学生实验室安全和急救知识掌握现状,探讨提高大学生实验室安全和急救知识水平的有效途径。整群随机抽样法抽取湖南某校263名化工学院一年级学生,随机分为实验组和对照组,向实验组大学生发放实验室安全和急救知识速查手册并进行讲解,对照组则不进行任何干预,每组均于干预前和干预后发放实验室安全和急救知识问卷进行测试。结果表明:第一次调查发现2个组大约有12个题目(占总题目的 48%)的回答正确率低于60%;干预后,实验组有21个题目的回答正确率高于干预前。第一次调查时2个组有4个问题的回答正确率在80%以上,且实验组的干预无法提高其正确率。大学生实验室安全和急救知识水平亟待提高,进行有效的干预可以提高他们这方面的知识水平。     

基于最大边缘分配算法的雷达博弈波形设计

实战背景下雷达目标先验信息有较大的不确定性,基于先验信息设计的波形不能满足参数估计的需要。为解决该问题,提出了一种博弈条件下的雷达波形设计方法。考虑到雷达与干扰机在电子对抗中的非同时性,采用Stackelberg博弈框架进行建模。该方法以优化雷达能量谱分布为策略,采用最大互信息准则建立效用函数。博弈过程中,雷达与干扰机各自根据对手策略优化发射波形,经过多次迭代,双方达到纳什均衡。仿真实验对比了均衡策略与maxmin策略与随机策略,证实了所提算法的有效性。     

“数字电子技术”课程思政教学改革研究

落实立德树人,实现三全育人,将思政融入到《数字电子技术》这门专业课程中,培养学生专业知识的同时,引导学生树立良好的人生观和价值观。通过重构本校的数字电子技术课程内容,挖掘思政元素,并润物细无声般融入到数字电子技术的教学改革中,并通过实际的案例讲解具体融入过程。     

助磨剂对钢渣粉磨效率及钢渣粉产品性能的影响

从钢渣粉产品质量特性及工艺参数等方面研究多种助磨剂对钢渣粉磨的影响.结果表明:所选择的助磨剂对钢渣的粉磨均有一定的助磨作用,表现在钢渣粉比表面积有所增加,钢渣粉活性指数有所提高,同时其初凝时间有所延长,终凝时间不变或缩短.掺助磨剂磨细钢渣的实际生产稳定可控,收到良好的降低能耗或提高产量的效果.