摘要：我们设计了一种不含金属的二维双层异质结构BC_(4)N/aza-CMP,该体系可在水溶液中将N2分子通过光催化作用还原为氨.通过密度泛函理论和非绝热分子动力学方法,我们发现该异质结构中的光生载流子遵循直接Z型迁移机制.这将有效分离光生电荷并使氮还原反应和氧发生反应分别在BC_(4)N层和aza-CMP层上进行,实现反应位点的空间分离.值得一提的是,BC_(4)N上的B原子可以有效吸附N2分子并激活N≡N键,这将降低氮还原反应的过电势并促进随后的质子化进程,且该异质双层具有适宜的带隙和带边位置,能够有效吸收太阳光并提供充足的驱动力来触发氧化还原反应,实现无任何牺牲剂辅助的光催化氨合成.本工作将为直接Z型固氮光催化剂的设计提供重要借鉴,并促进太阳能驱动的氨合成的发展.

摘要：Two-dimensional(2 D)van der Waals materials have been widely adopted as photocatalysts for water splitting,but the energy conversion efficiency remains *** the basis of first-principles calculations,we demonstrate that the 2 D Janus group-Ⅲchalcogenide multilayers:In Ga XY,M2XY and In GaX2(M=In/Ga;X,Y=S/Se/Te),are promising photocatalysts for highly-efficient overall water *** intrinsic electric field enhances the spatial separations of photogenerated carriers and alters the band alignment,which is more pronounced compared with the Janus *** solar-to-hydrogen(STH)efficiency with the upper limit of 38.5%was predicted in the Janus *** excitingly,the Ga vacancy of In Ga SSe bilayer effectively lowers the overpotentials of hydrogen evolution reaction(HER)and oxygen evolution reaction(OER)to the levels provided solely by the photogenerated *** theoretical results suggest that the 2 D Janus group-III chalcogenide multilayers could be utilized as highly efficient photocatalysts for overall water splitting without the needs of sacrificial reagents.

摘要：In this paper, we rewrote the equation of algebraic curve segmentswith the geometric informationonboth ends. The optimal or nearly optimal rationalparametric equation is determinedbythe principle that parametricspeedsat both endsareequal. Comparing withotherliteratures, the methodofthis paper has advantage in efficiency andiseasy to realize. The equation of optimal rational parameterization can be obtained directly by the information of both ends. Large numbers ofexperimental data show that our method hasbeen given withmore self-adaptability and accuracy than that ofotherliteratures, and if the parametricspeedat any end reaches its maximum or minimum value, the parameterization is optimal; otherwise itis close tooptimal rational parameterization.

摘要：Optimal parameterization of specified segment on the algebraic curves is a hot issue in CAGD and CG. Take the optimal approximation of arc-length parameterization as the criterion of optimal parameterization, and the optimal or close to optimal rational parameterization formula of any specified segment on the conic curves is obtained. The new method proposed in this paper has ad- vantage in quantity of calculation and has strong self-adaptability. Finally, a experimental comparison of the results obtained by this method and by the traditional parametric algorithm is conducted.

摘要：本文运用实验经济学分析方法,设计了生产企业、认证机构、监管机构之间博弈实验,探讨影响生产企业与认证机构行为选择的因素。实验结果表明:相比普通水产品,较高的市场溢价率能够促进生产企业选择生产地理标志水产品;以政府为代表的监管机构能够约束生产企业与认证机构共谋行为;关键可追溯信息真实完整性有利于促进认证机构对生产企业的有效监管。因此,应激发消费者地理标志水产品支付意愿,增强地理标志溢价效应;加大以政府为代表的监管机构抽查力度,坚决打击滥用、冒用地理标志现象;积极完善水产品可追溯体系建设,保证关键可追溯信息真实完整。