Iron-doped cobalt nitride nanoparticles (Fe–Co3N): An efficient electrocatalyst for water oxidation

The exploration of efficient, low-cost and earth-abundant oxygen-evolution reaction (OER) electrocatalysts and the understanding of the intrinsic mechanism are important to advance the clean energy conversion technique based on electrochemical water oxidation. In this work, Fe-doping Co₃N catalysts were successfully synthesized by a simple nitridation reaction of the Co_3-xFe_xO₄ precursor. This material exhibited a low overpotential of 294 mV at a current density of 10 mA cm^?2, and a small Tafel slope of 49 mV dec^?1 in 1 M KOH solution, superior to the performance of Co₃N and IrO₂. As revealed by the spectroscopic and electrochemical analyses, the enhanced OER performance mainly originates from the electronic modulation induced by the incorporation of Fe into Co₃N, benefitting the formation of CoOOH as active surface species and thus facilitating the OER process. These findings also demonstrate the introduction of heterogeneous element is a simple and effective strategy to regulate the OER property of the cobalt nitrides (Co₃N) catalysts.     

A numerical study on the performance of PEMFC with wedge-shaped fins in the cathode channel

The gas flow field design has a significant influence on the overall performance of a proton exchange membrane fuel cell (PEMFC). A single-channel PEMFC with wedge-shaped fins in the cathode channel was proposed, and the effects of fin parameters such as volume (0.5 mm³, 1.0 mm³, and 1.5 mm³), number (3, 5, and 9), and porosity of the gas diffusion layer (GDL) (0.2, 0.4, 0.6, and 0.8) on the performance of PEMFC were numerically examined based on the growth rate of power density (GRPD) and polarization curve. It was shown that wedge-shaped fins could effectively improve the PEMFC performance. With an increase in fin volume, the distributions of oxygen mass fraction in the outlet area of the cathode channel were lower, the drainage effect of the PEMFC improved, and GRPD also increased accordingly. Similar results were obtained as the number of fins increased. The GDL porosity had a greater effect than the wedge-shaped fins on the improvement in PEMFC performance, but the influence of GDL porosity weakened and the GRPD of porosity decreased as the porosity increased. This study provides an effective guideline for the optimization of the cathode channel in a PEMFC.     

产细菌素屎肠球菌SC-Y112的体外益生性及安全性评价

屎肠球菌SC-Y112是一种具有广谱抗菌性质的产细菌素乳酸菌，为更深入了解其菌株性质，本研究通过模拟胃肠液耐受实验、胆盐耐受实验、抗氧化活性测定、溶血活性测定、明胶液化实验、有害代谢物质检测、耐药性评价及肠球菌毒力基因检测对屎肠球菌SC-Y112的体外益生性质与安全性质进行分析评价。结果表明：屎肠球菌SC-Y112对模拟胃肠液耐受性强，在模拟胃液培养3 h存活率达73.66%，在0.3 g/100 mL的胆盐质量浓度下培养3 h后存活率达56.38%，其发酵24 h上清液总抗氧化能力达35.21 U/mL；此外，屎肠球菌SC-Y112不产生物胺、吲哚以及偶氮还原酶等有害代谢物质，无溶血现象，不溶解明胶，不携带常见肠球菌毒力基因，且对万古霉素敏感。研究结果可为菌株的进一步开发与应用提供科学依据。     

Failure mechanism of gently inclined shallow landslides along the soil-bedrock interface on ring shear tests

Bulletin of Engineering Geology and the Environment - There were many gently inclined shallow landslides along the soil-bedrock interface at a depth of 3–5 m in Nanjiang County, Sichuan...     

未开发历史保护街区更新提升设计环境行为研究——以哈尔滨花园街为例

花园街目前最无法解决的问题就是确定历史保护和改造的重点方向.研究使用者在旧街道空间中的行为以及与现有物理环境的互动,可作为未来改造和发展道路空间的一项参考.根据行为环境和空间关系学,采用行为映射法和视觉观察法、主成分分析和聚类法等,对街道使用者的行为和空间物理特征进行收集和处理.分析表明共三组行为,包括:(1)各种行为频繁发生路段;(2)各种行为较低频发生路段;(3)以通行和停滞为主的交叉口.对每类模式分别提出改善建议,并对花园街未来保护和发展提出相关策略.     

Transparent niobate glass-ceramics for optical limiting

The construction of nonlinear optical materials featuring asymmetric transmission of light is of great technological importance for various applications, including optical switching and optical power limiting. A significant challenge is the scalable fabrication of material candidates with good photochemical stability, high optical transmittance, and excellent optical limiting performance. Here, we present a nanocrystallization avenue for constructing hybrid optical limiting materials that exhibit ultrafast and robust optical limiting performance. The experimental results show that the controllable relaxation of a niobate glass may lead to the clustering of Nb-O units and contracting of the bandgap. It results in the notable improvement in nonlinear optical properties, including the enhanced saturation irradiance (380 GW/cm²), doubly increased nonlinear coefficient, and decreased limiting threshold (200 GW/cm²). Our results suggest a promising material that exhibits promising applications for protecting eyes and sensitive components from laser-induced damage.     

Interactions between dislocations and twins in deformed titanium aluminide crystals

Using scanning, transmission electron microscopy and aberration-corrected scanning transmission electron microscopy, we have studied the interactions between dislocations and twins in impact deformed polysynthetic twinned TiAl crystal. The 1/3?<?1$\overline{1}\overline{1}$] and 1/6?<?211] step dislocations on coherent twin boundaries reveal the interactions of glissile 1/2?<?101> dislocations with the coherent twin boundaries. An abnormal stacking fault was found adjacent to the coherent twin boundary. It has the same stacking sequence but different atom species in the [$\overline{1}$10] direction with an additional displacement of 1/4[$\overline{1}$10] in two neighboring {111} layers, and is likely induced by the slip of a 1/12[112] (i.e. 1/4[$\overline{1}$10] + 1/6[2$\overline{1}$1]) dislocation.