Study of the hexagonal to monoclinic celsian phase transition induced by magnetic phase nucleation in barium aluminosilicate glass-ceramics

The inert hexagonal to monoclinic celsian (H-M) phase transition extremely restricts the formation of celsian. In this study, Fe³⁺ dopants were incorporated into nonmagnetic barium aluminosilicate (BAS) glass-ceramics using Fe(NO₃)₃.9 H₂O as raw material for preparing the celsian phase. As the Fe-Ba mole ratio reached 0.238, the celsian phase can be obtained in magnetic BAS glass-ceramics. It implied that some magnetic reaction products facilitated the H-M phase transition. To examine the above inference, magnetic barium ferrite (BFO) additions were externally incorporated into a pure BAS glass matrix. Results suggested that BFO additions can significantly promote the H-M phase transition. When the addition of BFO was increased to 5 wt %, almost all of the hexacelsian phase was converted into the celsian phase. And the reason was that barium ferrite can act as a nucleation agent to induce the distorted hexacelsian phase decreasing the H-M phase transition barrier.     

Carbon nitride photocatalyst with internal electric field induced photogenerated carriers spatial enrichment for enhanced photocatalytic water splitting

Photocatalytic water splitting is a cost-effective way to convert sustainable solar energy into chemical energy. Among various photocatalytic systems, coupling the H₂- and O₂- evolving photocatalysts has been widely used in photocatalytic water splitting. However, due to the close spatial distance between surface electrons and surface holes, this heterogeneous material easily catalyzes the unwanted reverse reaction, limiting the solar energy conversion efficiency. Here we present a carbon nitride nanosheet (CNN) homojunction which possesses electrons-enriched region and holes-enriched region induced by the interfacial internal electric field. The reverse reactions are significantly suppressed by benefiting from the spatial separation of the oxidation (+2.21 V) and reduction (-1.19 V) regions. The homojunction exhibits efficient photocatalytic activity for H₂ and O₂ evolution (1270.5 and 36.0 μmol h⁻¹) with the scavenger. Meanwhile, the solar-to-hydrogen efficiency of overall water splitting was improved to 0.14%. This research provides a new way for semiconductor design in solar energy conversion applications.     

融合SMCF与加权直方图的视频人脸快速匹配方法

在视频流环境下,提出了一种融合序列蒙特卡罗滤波(SMCF)与加权直方图的快速人脸匹配方法,该方法以目标人脸在HSV空间下的加权直方图作为匹配特征,利用SMCF的采样和权值化处理技术预测人脸可能的匹配区域,通过最大后验估计实现目标的快速相似匹配。实验表明,采用在HSV下具有聚类特性的加权直方图特征可有效地适应复杂背景的干扰,同时SMCF的区域预测和最大化估计有效地减小了计算开销,增加了匹配的可靠性,可应用于人脸跟踪、视频监控及数字娱乐等领域。     

Self-assembled nanocotton-like Co–B–P/bacterial cellulose based carbon nanofiber as highly efficient electrocatalyst for oxygen evolution reaction

It is urgent and challenging to exploit highly efficient oxygen evolution reaction (OER) catalysts for water splitting. Bacterial cellulose based carbon nanofiber (BCCNF) is highlighted for its 3D network structure, abundant surface functional groups and good conductivity. Herein, based on the different molar ratio of P/B precursor, a series of nanocotton-like Co–B–P/BCCNF electrocatalysts have been designed and prepared via a simple electroless deposition. When the molar ratio of P/B precursor is 3/7, nanocotton-like Co–B–P/BCCNF catalyst exhibits prominent catalytic performances, delivering the current density of 10 and 50 mA cm^?2 at low overpotentials of only 262 and 391 mV, respectively. Besides, it exhibits long-term stability for durative OER in alkaline solution. This result indicates that nanocotton-like Co–B–P/BCCNF catalyst has great potential as OER catalysts for large-scale hydrogen production via water splitting.