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91.
Songhan Hu Zhangwen Long Yugeng Wen Jianbei Qiu Dacheng Zhou Jun’an Lai Dazhao Wang Jiacheng Pi Xizheng Li Qi Wang 《Journal of the American Ceramic Society》2020,103(11):6075-6080
It has been an urgent need for developing a new bright long-wave emitting phosphor to improve the color rendering index (CRI) of white light-emitting diodes (WLEDs). Here, based on the concept of oxygen vacancy-induced long-wave emission by Bi3+ doping, we selected BaSrGa4O8 as the matrix, which has a low-dimensional chain structure that can produce enough oxygen vacancies. After the introduction of Bi3+, orange emission was successfully achieved. To further improve the luminescence efficiency, the system of BaSrGa4O8:Bi3+,K+ was designed. Interestingly, although significant emission enhancement was obtained, the material showed reduced absorption with increased oxygen vacancies. More detailed experimental evidences confirm that oxygen vacancies can activate Bi3+ to achieve long-wave emission. Our results provide a new way to design Bi3+-based long-wave emitting phosphors with low-dimensional crystal structure. Finally, a WLED device containing BaSrGa4O8:Bi3+,K+ was fabricated and exhibited an enhanced CRI, which shows a promising application in WLEDs. 相似文献
92.
Katarzyna Krawczyk Jakub Sawicki 《International journal of molecular sciences》2013,14(6):11376-11391
RNA polymerase type I (plastid-encoded polymerase, PEP) is one of the key chloroplast enzymes. However, the rpo genes that encode its subunits (rpoA, rpoB, rpoC1 and rpoC2) are relatively rapidly evolving sequences. The aim of this study was to investigate the rate of the molecular evolution of rpo genes and to evaluate them as phylogenetic markers on the example of the genus Lamium L. (Lamiaceae). The analyzed genes were shown to differ in the level of variation, rate of intragenic mutations, phylogenetic informativeness, and in the impact of these mutations on the properties of encoded peptides. Destabilizing effects of the positive pressure were observed in all genes examined coding for PEP enzyme. We have demonstrated the relationship between mutations fixed by positive selection and the separation of phylogenetic lines within the genus Lamium. The study showed also that the rpo genes were reliable phylogenetic markers, useful in the reconstruction of interconnections of species belonging to the same genus. Of the four tested genes, the most promising phylogenetic marker was rpoA gene, while the least useful gene appeared to be rpoC1. 相似文献
93.
This paper presents a fully automatic system intended to detect leaks of dielectric fluid in underground high-pressure, fluid-filled (HPFF) cables. The system combines a number of artificial intelligence (AI) and data processing techniques to achieve high detection capabilities for various rates of leaks, including leaks as small as 15 l per hour. The system achieves this level of precision mainly thanks to a novel auto-tuning procedure, enabling learning of the Bayesian network – the decision-making component of the system – using simulated leaks of various rates. Significant new developments extending the capabilities of the original leak detection system described in [1] and [2] form the basis of this paper. Tests conducted on the real-life HPFF cable system in New York City are also discussed. 相似文献
94.
How to apply the global optimization technique, simulated annealing, and to explore the operation of batch reactors is addressed in this study. Based on the operating purposes and the imposed constraints, the batch reactor operations are first formulated as two optimal control problems: the maximal yield (or conversion) problem and the minimal operating time problem. The problems are then converted into non‐linear programming problems by the concept of control vector parameterization. The converted problems are solved by the algorithm derived from simulated annealing to determine the optimal operating policy and the performance index. These results are useful in assessing design and operation of batch reactors. In this article, the CSTR model is used to demonstrate the convenience and robustness of the proposed algorithm. Two typical reaction models are used to discuss the operations based on the optimal solutions. 相似文献
95.
96.
采用超音速火焰喷涂技术沉积含3种不同(Mo+B)/(Ni+Cr)质量比(1:1,2:1和3:1)的Mo-B-Ni-Cr球磨复合粉末以原位反应制备获得MoB/NiCr涂层。采用扫描电子显微镜(SEM)和X射线衍射仪(XRD)分析了MoB/NiCr涂层的组织结构和物相。同时讨论了不同(Mo+B)/(Ni+Cr)质量比对涂层的组织结构、硬度、结合强度和耐腐蚀性能的影响。研究结果表明,(Mo+B)/(Ni+Cr)质量比为1:1的MoB/NiCr涂层孔隙率最低及涂层厚度最大。在3种涂层中均原位反应生成了Mo2NiB2三元硼化物,且随着(Mo+B)/(Ni+Cr)质量比的增加,涂层中三元硼化物含量随之增加,涂层的硬度值增加,结合强度反而随之降低;由于涂层中三元硼化物的原位生成,MoB/NiCr涂层的硬度值均高于316L不锈钢基体。通过能谱和XRD分析发现,经过360 h熔融锌腐蚀试验后,涂层表层中没有发现锌元素及其金属间化合物,然而随着(Mo+B)/(Ni+Cr)质量比的增加,涂层的孔隙率增加及厚度降低。最后,综合分析可得,相比其他涂层,(Mo+B)/(Ni+Cr)质量比为1:1的MoB/NiCr涂层具有更好的耐熔融锌腐蚀能力。 相似文献
97.
挠性摆式微硅加速度计的有限元分析 总被引:4,自引:1,他引:4
】微硅加速度计是近年来发展起来的新型器件,在结构设计阶段必须对其进行力学分析,以期对使用条件下的摆片位移、应力等作到心中有数。本文采用有限元分析方法对挠性摆式微硅加速度计进行有限元分析,其中包括对未封装及封装后实体单元进行敏感轴位移、侧向位移、横向灵敏度、受力情况等分析。分析结果表明所设计的微硅加速度计符合仪表性能要求。 相似文献
98.
99.
100.
高亲水性聚(苯乙烯-二乙烯基苯)多孔微球的制备及亲水性研究 总被引:1,自引:0,他引:1
以环状马来酸酐为改性剂,分别采用改进的二步种子溶胀法和悬挂双键接枝法制得了高亲水性的聚(苯乙烯-二乙烯苯)/马来酸酐共聚多孔微球(PSt-DVB-co-MAH)及聚(苯乙烯-二乙烯苯)接枝马来酸酐多孔微球(PSt-DVB-g-MAH)。用FT-IR证明了改性产物中马来酸酐的存在;用TEM、SEM观察了改性前后微球的内、外部形貌;酸碱滴定法考查了MAH加入量对微球孔径的影响;用极性熊果苷的吸附对比实验验证了改性效果。结果表明,两种方法制得的改性微球在形态上与没改性前的微球略有差别,但当共聚法St∶DVB∶MAH=10∶8∶2及接枝法P(St-DVB)微球∶MAH=5∶3时,所得亲水微球均保持了较好的多孔形貌且亲水性比未改性的增大5倍以上。 相似文献