The exploration of novel long lasting red phosphors is still of importance due to expected commercial applications and scientific interests. In this work, we reported the red long lasting ...phosphorescence（LLP） from Eu^3＋ doped BiOCl semiconductor polycrystals. The LLP property of the red phosphor is relatively weak due to less trap density, but the excitation band of LLP stems from the energy gap transition of semiconductor, offering experimental evidence for energy transfer between BiOCl semiconductor and Eu^3＋ ions. Although the afterglow duration of Eu^3＋ doped BiOCl was short temporarily, this work may open a novel kind of red LLP phosphors.
Praseodymium （Pr） was impregnated to CeO2-ZrO2 solid solution by an impregnation method. The as-obtained Pr modi- fied CeO2-ZrO2 was impregnated with 1 wt.% Pd to prepare the catalysts. The structure ...and reducibility of the fresh and hydrother- really aged catalysts were characterized by X-ray diffraction （XRD）, Raman, X-ray photoelectron spectroscopy （XPS）, CO chemi- sorption and H2 temperature-programmed reduction （H2-TPR）. The oxygen storage capacity （OSC） was evaluated with CO serving as probe gas. Effects of impregnated Pr on the structure and oxygen storage capacity of catalysts were investigated. The results showed that the aged Pr-impregnated samples had much higher OSC and better reducibility than the unmodified ones. The scheme of structural evolutions of the catalysts with and without Pr was also established. Partial of the impregnated Pr diffused into the bulk of CeO2-ZrO2 during ageing, which inhibited the sintering, and increased the amount of oxygen vacancies in CeO2-ZrO2 support. Furthermore, those impregnated Pr species which covered on the surface of the support obstructed the strong metal-support interaction between Pd and Ce so as to reduce the encapsulation of Pd as well as the back spill-over of the oxygen during the catalytic process.
The exploration of novel long lasting red phosphors is still of importance due to expected commercial applications and scientific interests. In this work, we reported the red long lasting ...phosphorescence（LLP） from Eu3+ doped BiOCl semiconductor polycrystals. The LLP property of the red phosphor is relatively weak due to less trap density, but the excitation band of LLP stems from the energy gap transition of semiconductor, offering experimental evidence for energy transfer between BiOCl semiconductor and Eu3+ ions. Although the afterglow duration of Eu3+ doped BiOCl was short temporarily, this work may open a novel kind of red LLP phosphors.
Road horizontal alignment contains three elements: straight line, circular arc, and clothoid. In AutoCAD, clothoid can only be fitted by polyline or spline, and the graphics which are separated from ...the road data are independent of each other. Therefore, it is necessary to develop a new curve for road horizontal alignment. Firstly, the differential approximation and series integration methods for clothoid were discussed. Secondly, the geometric formulae for road line which contain the three elements were derived as a whole. Then, the advantages and feasibility of customizing a road line class, which was derived from the curve base class, were analyzed based on ObjectARX (AutoCAD Runtime eXtension) techniques. Finally, the data structure and operations for the road line class were stressed. The experimental results show that the road line can integrate the road elements, graphics and data to implement the graphics-oriented design, which can be widely used in road alignment design.
Recently, Wang et al. presented a new construction of attribute-based signature with policy-and-endorsement mechanism. The existential unforgeability of their scheme was claimed to be based on the ...strong Diffie-Hellman assumption in the random oracle model. Unfortunately, by carefully revisiting the design and security proof of Wang et alfs scheme, we show that their scheme cannot provide unforgeability, namely, a forger, whose attributes do not satisfy a given signing predicate, can also generate valid signatures. We also point out the flaws in Wang et al.＇s proof.
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