Site occupation and energy transfer in full color emitting phosphor Ba2Ca(BO3)2:Ce3+(K+),Eu2+,Mn2+

White light-emitting diodes (WLEDs) fabricated by single-phase full color emitting phosphor are an emerging solution for health lighting. The crystallographic site occupation of activators in a proper host lattice is crucial for sophisticated design of such phosphor. Here, we report a high quality white light-emitting phosphor Ba₂Ca(BO₃)₂:Ce³⁺(K⁺),Eu²⁺,Mn²⁺ with spectral distribution covering whole visible region. Blue light emission originates from Ce³⁺ ions occupying preferentially Ba²⁺ site by controlling synthesis conditions. Green and red lights are obtained from Eu²⁺ occupying Ba²⁺ (and Ca²⁺) site and Mn²⁺ occupying Ca²⁺ site, respectively. In this triple-doped phosphor, strong red emission with a low concentration of Mn²⁺ is realized by the efficient energy transfer from Ce³⁺ and Eu²⁺ to Mn²⁺. Furthermore, high quality white light is accomplished by properly tuning the relative doping amount of Ce³⁺(K⁺)/Eu²⁺/Mn²⁺ based on efficient simultaneous energy transfer. The results indicate that Ba₂Ca(BO₃)₂:Ce³⁺(K⁺),Eu²⁺,Mn²⁺ is a promising white light-emitting phosphor in WLEDs application.     

Growth of yolk-shell CuCo2S4 on NiO nanosheets for high-performance flexible supercapacitors

A poor electrical conductivity and short cycle life limits the wide application of transition metal oxides in energy storage applications. In this study, yolk-shell structured CuCo₂S₄ was grown on NiO nanosheets (NiO@CuCo₂S₄) via a hydrothermal method and vulcanization, which combined the synergistic interactions between Ni, Co, and Cu. The effect of varying the amount of the vulcanizing agent (thiourea) on the electrochemical performance of NiO@CuCo₂S₄ was also investigated. Moreover, the amount of thiourea not only tuned the morphology of the composite, but significantly influenced its electrochemical performance. When the Cu²⁺: Co²⁺: thiourea molar ratio in the precursor solution was 1:2:6, the obtained NiO@CuCo₂S₄ exhibited the best electrochemical performance of the various systems examined, with a specific capacitance of 1658 F g^?1 being achieved at 1 A g^?1. Density functional theory calculations further confirmed the excellent synergistic effect between NiO and CuCo₂S₄. In addition, the asymmetric supercapacitor composed of a NiO@CuCo₂S₄ positive electrode reached an ultrahigh energy density of 73 Wh kg^?1 at a power density of 802 W kg^?1, as well as excellent cycling stability (i.e., 91% capacitance retention after 5000 cycles). These results suggest that NiO@CuCo₂S₄ is a promising candidate for use in energy storage applications.     

老年人肠道乳酸菌的分离与鉴定及其来源发酵乳杆菌的遗传进化分析

首先对湖北襄阳和恩施地区的健康老年人肠道乳酸菌进行分离与鉴定，然后从中选择发酵乳杆菌（Lactobacillus fermentum）进行多位点序列分型（multilocus sequence typing，MLST）分析。结果显示，基于可培养方法，湖北襄阳与恩施地区老年人肠道乳酸菌可以鉴定为以乳杆菌属（Lactobacillus）为主的5 个菌属，15 个种。总的来说，发酵乳杆菌和唾液乳杆菌（L. salivarius）占老年人肠道源乳酸菌分离株总量的55%左右，表明人体肠道可以作为发酵乳杆菌的重要分离来源。基于8 个持家基因的MLST分析表明，25 株来源于肠道的发酵乳杆菌可以划分为25 个序列型，具有极高的遗传多样性；基于选择压力分析与phi-test，选用的8 个持家基因均受到纯化选择作用，且其中仅基因rpoB显著经历了基因重组事件；另外，基于Prim’s和goeBURST的进化分析表明，一半左右的肠道源发酵乳杆菌倾向于形成单独的分支，表明它们具有一定的宿主特异性，可能的原因是为适应肠道环境，这些发酵乳杆菌经历了有异于发酵食品生境的进化历程。     

羧酸盐配合物的热分解研究进展

羧酸盐配合物具有非常广泛的用途,热稳定性作为其非常重要的一种性质而被深入研究。本文对稀土、碱土和过渡金属羧酸盐配合物的热分解反应过程,以及芳香族羧酸盐配合物的热分解过程的动力学分析方面的研究进展进行了综述,以期为该类物质的实际应用提供更全面的参考数据。     

Response characteristics and mechanism of the strength and energy of schist to the schistosity orientation and water

Bulletin of Engineering Geology and the Environment - In this study, uniaxial compression testing was carried out to investigate the response of quartz mica schist to water in terms of strength and...     

Water pricing in Tunisia: Can an original rate structure achieve multiple objectives?

In the context of anthropic pressures, the Tunisian Water Utility tries to achieve three objectives: financial (achieving full-cost recovery), social (ensuring access for all), and environmental (incentivizing users to save a scarce resource). After a theoretical review of water pricing, the paper presents how successive reforms in Tunisia have gradually set up an original pricing structure that has become the main instrument of the sector's policy. Using different data and methods, we investigate how each of the three objectives is reached through pricing. We conclude that this pricing policy has led to a relatively stable but partial equilibrium.     

符合阿贝原则的数控机床几何误差建模

为提高现有数控机床空间误差分析方法的准确度,本文基于阿贝原则对齐次转换矩阵(HTM)几何误差补偿模型进行优化。首先,推导出XYFZ型三轴机床适用的HTM几何误差补偿模型并给出模型正确使用的前提条件;然后,基于阿贝原则分析了三轴机床的空间误差传递机理,指出阿贝误差对机床定位精度的影响,给出理论计算公式并在机床运动轴上进行实验验证;最后,基于阿贝原则和布莱恩原则对现有的HTM几何误差补偿模型进行优化,采用该模型拟合体对角线空间误差,并与实测机床体对角线误差进行对比验证。现有HTM几何补偿模型可将机床空间误差由41.15μm补偿至16.37μm,补偿率为60.22%;优化后的补偿模型可将机床空间误差补偿至5.32μm,补偿率为87.07%,提高了26.85%。实验结果表明,优化后的补偿模型更加合理,进一步改善了空间误差的补偿精度。     

新型糠酮呋喃树脂的研究

以聚乙烯醇、三聚氰胺为改性剂,改性由环己酮、尿素、甲醛和糠醇缩合而成的糠酮呋喃树脂,该树脂是一种新型铸造用的呋喃树脂。反应分三步：酮醛缩合、脲醛缩合、合成树脂。改性呋喃树脂氮含量、游离甲醛含量都明显降低,树脂强度高,粘度小,附着力好,且该工艺具有生产能耗低,工艺简单,产品耐酸耐碱性能好等优点。文章介绍用新型催化剂合成糠...     

校企合作模式培养应用型本科人才的探讨

校企合作培养模式是提高理工类应用型本科教育阶段的教育质量,加快教学改革的步伐,满足经济社会快速发展需要的有效途径,实现学校、学生、企业三方的友好沟通合作。文中简明阐述了实现校企合作模式培养的主要途径,其中包括充分资源共享互换交流模式和深度介入定向培养模式。     

电子招投标制度的应用研究

阐述了电子招投标的系统结构及其使用方法,通过研究电子招投标在建设工程招投标中的应用,分析了我国电子招投标系统建设的现状以及电子招投标在普及实行中存在的问题,并针对问题提出了具体的解决方案。