Mechanistic Insights and Photodegradation of Heterostructure Graphene Oxide/Titanium Dioxide

Topics in Catalysis - In this study, the electrospinning method was used to prepare graphene oxide/titanium dioxide (GO/TiO2) nanofibers with different contents of GO as photocatalysts used to...     

新型装配式冰场受力性能试验与模拟分析

为在2022年冬奥会期间将国家游泳中心泳池场地改造为冰壶场地,结合临时场地的新型制冰方式,提出了一种全装配式的冰壶场地及支承结构体系的构造作法.对此装配式冰场进行了现场试验测试和有限元受力性能分析,研究了装配式冰场的自振频率和振型特点,分析了冰场在使用荷载作用下的整体变形和各组件的应力水平,探讨了极端荷载作用下冰面受力、变形及开裂等关键问题.研究表明,所提装配式冰场方案具有较大刚度和承载力,能够满足冬奥会冰壶比赛对冰面的要求；此类冰场宜使用轻型浇冰车作业,大型浇冰车轮压引起的弯矩和剪力作用下冰面存在开裂的可能.     

城市街道峡谷单侧自然通风研究进展

自然通风广泛存在于城市之中，了解城市自然通风建筑室内环境质量现状及存在的问题，是改善城市建筑室内环境质量的基础. 通过文献整理，首先研究城市街道峡谷中单侧自然通风的驱动因素，其次从建筑几何特征、通风能力、污染率、颗粒物浓度以及街谷设施等方面综述单侧自然通风的相关研究，最后提出建议. 研究表明，合理的展弦比、更好的城市布局以及精心的街谷设施设计能够最大限度地利用单侧自然通风，提升城市街道峡谷的室内环境品质.     

Fabrication of direct Z-scheme FeIn2S4/Bi2WO6 hierarchical heterostructures with enhanced photocatalytic activity for tetracycline hydrochloride photodagradation

A series of direct Z-scheme FeIn₂S₄/Bi₂WO₆ hierarchical heterostructures with intimate interface contacts were synthesized by in-situ growth route and characterized by systematical analyses. All as-prepared FeIn₂S₄/Bi₂WO₆ nanocomposites showed significantly enhanced photocatalytic activity towards photodegradation for the removal of tetracycline hydrochloride (TCH) in comparison with individual FeIn₂S₄ and Bi₂WO₆. Meanwhile, the highest photocatalytic degradation activity can be achieved by modulating adding amount of FeIn₂S₄ in FeIn₂S₄/Bi₂WO₆ nanocomposites and the optimized component ratio of FeIn₂S₄ to Bi₂WO₆ is determined to be 10 wt%. The enhanced photocatalytic activity could be ascribed to efficient separation between photogenerated holes and electrons based on the construction of direct Z-scheme system. The high photocatalytic stability of resultant 10 wt% FeIn₂S₄/Bi₂WO₆ nanocomposites was revealed through six successive recycling reactions. The main intermediate generated during TCH photodegradation was explored by HPLC-MS. Besides, the direct Z-scheme photocatalytic mechanism was confirmed by band position analysis, electron spin resonance (ESR) and active species capture experiment.     

Absorption effect of pure nickel on the corrosion behaviors of the GH3535 alloy in tellurium vapor

In this study,pure Ni was demonstrated to pro-tect the GH3535 alloy from Te vapor corrosion because of its strong absorption capacity.Severe Te corrosion of a single GH3535 alloy sample occurred in Te vapor at 700℃,which manifested as complex surface corrosion products and deep intergranular cracks.However,when pure Ni and the GH3535 alloy were put together in the vessel,the GH3535 alloy was completely protected from Te corrosion at the expense of the pure Ni.Thermody-namic calculations proved that the preferential reaction between pure Ni and Te vapor reduced the activity of Te vapor considerably,preventing the corrosion of the GH3535 alloy.Our study reveals one potential approach for protecting the alloys used in molten-salt reactors from Te corrosion.     

Flexible piezoelectric energy harvesters with graphene oxide nanosheets and PZT-incorporated P(VDF-TrFE) matrix for mechanical energy harvesting

Flexible piezoelectric energy harvesters (PEHs) have attracted extensive interest because of their ability to transform mechanical energy into electric power. Here, PEHs were fabricated using P(VDF-TrFE)-based piezoelectric composite films containing lead zirconate titanate (PZT) powder and –OH-functionalized graphene (HOG) nanosheets (HOG-P/P). Among all composites, a high open-circuit voltage (Voc) of approximately 50 V_p-p and a maximum power density of 1.4 μW/cm² were obtained from a HOG-P/P PEH with 0.10 wt% HOG nanosheets and 15 wt% PZT under bending–releasing mode. Moreover, the PEH exhibited a stable voltage output after 3000 bending–releasing cycles. In addition, the PEH harvested mechanical energy from human body movements and generated an output voltage and current of 60 V and 8 μA during the finger bending–releasing process, lighting up 30 commercial white LEDs. The enhanced piezoelectric performance can be attributed to the introduction of HOG nanosheets and PZT powder. This work provides an effective strategy for improving the output performance of P(VDF-TrFE)-based PEHs.     

Hemodynamic Forces Regulate Cardiac Regeneration-Responsive Enhancer Activity during Ventricle Regeneration

Cardiac regenerative capacity varies widely among vertebrates. Zebrafish can robustly regenerate injured hearts and are excellent models to study the mechanisms of heart regeneration. Recent studies have shown that enhancers are able to respond to injury and regulate the regeneration process. However, the mechanisms to activate these regeneration-responsive enhancers (RREs) remain poorly understood. Here, we utilized transient and transgenic analysis combined with a larval zebrafish ventricle ablation model to explore the activation and regulation of a representative RRE. lepb-linked enhancer sequence (LEN) directed enhanced green fluorescent protein (EGFP) expression in response to larval ventricle regeneration and such activation was attenuated by hemodynamic force alteration and mechanosensation pathway modulation. Further analysis revealed that Notch signaling influenced the endocardial LEN activity as well as endogenous lepb expression. Altogether, our work has established zebrafish models for rapid characterization of cardiac RREs in vivo and provides novel insights on the regulation of LEN by hemodynamic forces and other signaling pathways during heart regeneration.     

Assessment of Effective Monitoring Sites in a Reservoir Watershed by Support Vector Machine Coupled with Multi-Objective Genetic Algorithm for Sediment Flux Prediction during Typhoons

Water Resources Management - Effectively assessing crucial monitoring sites with suspended sediment concentration (SSC) is a vital challenge for achieving accurate prediction of sediment flux on...     

钢筋UHPC梁正截面抗弯承载力计算方法

超高性能混凝土(ultra-high-performance concrete，UHPC)是一种高强、高韧性和高耐久性的新型水泥基复合材料，具有广阔的应用前景。由于UHPC内的钢纤维能有效控制裂缝开展并提高UHPC的抗拉强度，因此，UHPC构件抗弯承载力分析时，一般计入截面受拉区UHPC的抗拉作用，但对于如何考虑受拉区UHPC的抗弯贡献，国内外相关研究结果间存在较大分歧，因此值得进一步研究。首先，编制钢筋UHPC梁正截面抗弯承载力分析程序，分析不同设计参数对截面受拉区UHPC抗弯贡献的影响。结果表明：配筋率、梁高、钢纤维长度、截面形状和预应力水平是影响受拉区UHPC抗弯贡献的主要参数。基于参数分析结果的回归分析，提出截面受拉区UHPC的均匀分布应力折减系数k的计算公式；通过引入受拉翼缘面积折减系数kf，考虑不同截面形状的影响。在此基础上，提出不同弯曲破坏模式下钢筋UHPC梁抗弯承载力的简化计算方法，并以国内外115根钢筋UHPC梁抗弯承载力试验结果验证所提方法的适用性。