厌氧氨氧化应用于城市主流污水处理工艺的研究进展

厌氧氨氧化(Anammox)技术作为近年来新兴的自养脱氮工艺,具有无需外加碳源、低污泥产量、低能耗等优势.文中总结了厌氧氨氧化应用于主流污水处理工艺时面临的困难挑战,分析了厌氧氨氧化处理污水的最新研究进展,阐述了厌氧氨氧化菌(AnAOB)的截留、硝酸盐氧化菌(NOB)的抑制、有机物的不利影响等问题的具体解决方案.在节能...     

FeCoCrNiZr x 高熵合金的磁性和电化学性能

采用真空电弧熔炼法制备了不同Zr含量的FeCoCrNiZr_x（x=0.5,0.75,1）高熵合金。研究了Zr含量对合金组织、磁性能和电化学腐蚀性能的影响。采用X射线衍射仪、扫描电镜、振动样品磁力计和电化学工作站对合金的磁性能和电化学腐蚀能力进行了研究。结果表明：FeCoCrNiZr_x合金具有典型的共晶组织,由面心立方固溶体和C15 Laves相组成。随着Zr含量的增加,合金硬度呈先增大后减小的趋势。根据合成的静态滞回曲线可以看出,FeCoCrNiZr_0.5合金具有顺磁性和铁磁性的混合型特征,FeCoCrNiZr_0.75合金表现为顺磁性,FeCoCrNiZr₁合金表现为典型的铁磁性。同时,FeCoCrNiZr_x合金在3.5%（质量分数）NaCl溶液中经历活化与钝化转变。当合金中的Zr含量为0.75%（原子分数）时,合金极化电阻具有最大的阻抗电容半径,钝化膜的耐腐蚀能力最强。     

Conceptual Design and Finite Element Analysis of STR-3 Feeder for ITER

The three structure (STR) cooling feeders of the international thermonuclear experimental reactor play an important role in removing heat loads from the coils cases of the superconducting magnets system. In this paper, the materials choice and conceptual design of STR-3 feeder are presented, then the structural analyses are performed based on the finite element method, which is used to evaluate the mechanical characteristics of STR-3 feeder. The results show that the structural design is basically reasonable, but the U bend or S bend structure near terminal box is necessary. Furthermore, the further structural optimization, reducing the heat leakage to cryopipes, radiation of composite insulation materials, overpressure protection and seismic analysis proposals are put forward.     

纳米材料及其三维结构修饰电极检测多巴胺的研究进展

纳米材料构建的化学修饰电极用于多巴胺电化学检测已经被广泛研究。当前电极研究策略主要为采用复合材料并构建三维结构以增大吸附表面积。本综述总结了目前常用的纳米碳修饰材料与纳米金属修饰材料,比较分析了其表面结构形貌对多巴胺吸附的影响及吸附机制,总结了目前常用的构建三维修饰电极的方法。分析结果表明,相对于一维形貌,三维形貌结构的修饰电极往往具有更好的检测能力,三维结构不仅能显著增大表面积,提供更多的吸附位点,还可能产生“薄膜效应”,该效应在一定程度上能提高响应灵敏度,但超过一定限度会减缓响应时间,第一性原理分析表明,多巴胺在纳米修饰电极材料表面的吸附机制是化学吸附。最后指出了在改进修饰电极结构设计合理性、增强抗干扰性和提高选择性,以及新的检测控制机制分析方面需要进一步研究。     

Low thermal expansion material Bi0·5Ba0·5FeO3-δ in application for proton-conducting ceramic fuel cells cathode

The cobalt-free material of Bi³⁺-doped BaFeO_3-δ (BBFO) is synthesized and applied as a cathode material for intermediate-temperature solid oxide fuel cells (IT-SOFCs) with proton conducting electrolyte Ba(Zr_0·1Ce_0·7Y_0.2)O₃ (BZCY). The as-prepared BBFO demonstrates a tetragonal structure with sufficient chemical compatibility, high thermal stability and low thermal expansion coefficient. BBFO exhibits higher electrical conductivity of 4.1 S cm⁻¹compared to the parent material BaFeO_3-δ (BFO) of 3.5 S cm⁻¹. The composite cathode BBFO-BZCY with the mass ratio of 7:3 presents a relatively low R_p of 0.128 Ω cm² at 700 °C in air. According to the oxygen reduction reaction process, the rate-determining step is transformed from charge transfer to oxygen gas (O₂) adsorption-dissociation with the rising temperature. In addition, the performance of the anode-supported cell NiO-BZCY∣BZCY∣BBFO-BZCY is 120 mW cm⁻² as the thickness of electrolyte is 150 μm. It thus promises BBFO as a novel cathode for proton-conducting ceramic fuel cells.     

硫酸盐侵蚀溶液pH值对硅酸盐水泥浆体C-(A)-S-H凝胶结构的影响

C-（A）-S-H凝胶的结构不仅受水泥基材料自身组成的影响,更受其所处环境的影响。本文利用固体核磁共振（NMR）并结合去卷积技术,探究硫酸盐侵蚀溶液pH值对硅酸盐水泥浆体中C-（A）-S-H凝胶结构的影响。结果表明:硫酸盐侵蚀过程中,前期进入凝胶中的Al3+后期又会脱出,使凝胶中四配位铝（Al[4]）/Si比值降低。侵蚀溶液pH值的降低促进了凝胶中Al[4]的脱出,使Al[4]的峰位向负值移动;同时也促进了[SiO₄]（[AlO₄]）四面体间的聚合,使C-（A）-S-H凝胶平均分子链长（MCL）增加。此外,侵蚀溶液pH值的降低,促进了浆体的水化,但抑制了浆体中钙矾石（AFt）的生成。      

Deformation and fracture of Cu-SiO2 bicrystals with [011] twist boundaries

Several kinds of Cu-SiO₂ bicrystals having [011] twist boundaries with different misorientation angles were tensile tested at various temperatures from 473–1023 K at strain rates from 4.2 × 10⁻⁵–4.2 × 10⁻³ s⁻¹ in vacuum. Most of bicrystals fractured intergranularly. The grain-boundary strength and fracture behavior of the Cu-SiO₂ bicrystals strongly depended on the grain-boundary character, temperature and strain rate. As the misorientation angle or grain-boundary energy increases, grain-boundary fracture takes place more easily at lower temperatures with lower fracture stresses. Furthermore, fracture stress and elongation to fracture decrease almost monotonically with increasing temperature and decreasing strain rate. The observed grain-boundary character and test condition dependence of grain-boundary strength can be understood reasonably by considering the occurrence of stress-concentration sites around the grain-boundary SiO₂ particles to form voids and cracks caused by grain-boundary sliding.     

Liquid crystalline polymers and elastomers

The results of experiments and theory correlate increasingly well in the investigation of liquid crystalline polymers. Current work focuses on rheology and the behavior of blends of thermotropic LC polymers, due to reemerging economic interest in these materials. Research on liquid crystalline elastomers concentrates on potential applications such as artificial muscles and lasing.     

Systematical study on the roles of transition alloying substitutions on anti-disproportionation reaction of ZrCo during charging and releasing hydrogen

Intermetallic alloy ZrCo is believed to be a good substitution for uranium to store tritium. Nevertheless, disproportionation reaction often happens during the hydriding and dehydriding processes, and hydrogen storage property of ZrCo is therefore degraded. Alloying elements are often used to substitute Zr or Co in ZrCo to restrain disproportionation reaction. However, many experimental results do not agree with each other, and it lacks overall tendency for all transition metal elements. In this work, systematical ab initio calculations are performed to study more than 20 transition alloying elements to substitute Co and Zr in ZrCoH₃ to study the anti-disproportionation effects. It is found that substitution of Co by transition metal elements on anti-disproportionation reaction is unconspicuous, and only Ni can enlarge Zr–H bond length and decrease the volume of 8e site, presenting anti-disproportionation effect, which qualitatively agrees with the previous experiments. In contrast, all transition alloying elements considered except Fe, Co, Ni, Ru, Rh, Pd, Os and Ir replacing Zr can both enlarge the length of Zr–H bond and decrease the volume of 8e site, and thus restrain the disproportionation effects. At last, two-dimensional charge density and density of states are calculated to analyze the underlying mico-mechanisms affecting the effects of transition alloying elements on anti-disproportionation reaction.     

基于高分一号遥感卫星的渤海湾悬浮泥沙时空分布反演

悬浮泥沙是评价II类水体水质的重要参数之一,近海岸水域悬浮泥沙对重金属、营养盐等具有一定的吸附作用,悬浮泥沙的分布特征在一定程度上反映着污染物的迁移和循环,因此研究悬浮泥沙对渤海湾建设和环境保护具有重要意义。为探究渤海湾水域悬浮泥沙浓度 和分布的变化特征,利用高分一号多光谱卫星影像,通过采用波段组合的方式对悬浮泥沙含量指数反演提取,反演得到2019年9个月的渤海湾悬浮泥沙指数,分析发现渤海湾悬浮泥沙含量在冬季受季风影响较高,春季和夏季的时候渤海湾高浓度悬浮泥沙向近岸收缩,秋季 悬浮泥沙分布格局有正在向冬季过渡的趋势,本文研究可为渤海湾的生态环境保护和工业开发提供重要的科学依据和参考价值。