Novel adamantane-based periodic mesoporous organosilica film with ultralow dielectric constant and high mechanical strength

Journal of Sol-Gel Science and Technology - In this work, a novel bridged organosilane precursor, adamantane-bridged organosilane (ADBO), was synthesized successfully which was employed to prepare...     

带负顾客的Geom/Geom/1单重休假排队(英文)

本文研究了正负顾客到达均服从几何分布,服务台在工作休假期以较低的服务速率运行的 Geom/Geom/1休假排队.运用嵌入马尔科夫链和矩阵分析法,得到了系统中等待队长和稳态队长的概率母函数,并从证明过程和结果中,分别得到了服务台在闲期、忙期、工作休假期、正规忙期的概率.     

江西湖田窑古代瓷器中稀土元素的分析及产地的研究

古陶瓷的年代和产地的研究一直是考古学的重要内容之一。古陶瓷中微量和痕迹的稀土元素在指示古陶瓷原料的产地和年代方面具有决定性的作用。本文用中子活化分析方法研究了江西湖田窑出土的398片不同釉色的古代瓷胎中La,Sm,Ce,Nd,Eu,Tb,Yb和Lu 8种稀土元素的含量并对分析数据进行了处理。分析结果表明:江西湖田窑从五代到明代中期600多年的制瓷工艺和配方,既有连续性,又有创新性;五代、宋代、元和明四个不同历史时期烧制的瓷胎中稀土元素含量有明显的差异,同朝代不同历史时期烧制的瓷胎在轻重稀土的富集上又有所差异。这些差异揭示了其胎料的来源和配方既有同源性,又有差异性。另一方面,瓷胎中稀土元素的含量和差异又体现了江西湖田窑瓷器的年代和产地的特征。     

Amorphizing of Ag Nanoparticles under Bioinspired One‐step Assembly of Fe3O4‐Ag/rGO Hybrids via Self‐redox Process with Enhanced Activity

Efficient and reusable nanocatalysts fabricated via a facile assembly are highly desirable for the cost‐effective hydrogenation reduction. Inspired by a fishing process with a fishnet, multifunctional nanostructured catalysts are rationally designed to combine interesting features via the self‐redox assembly of Fe₃O₄‐Ag composites on reduced graphene oxide (rGO) (Fe₃O₄‐Ag/rGO). In detail, Fe₃O₄ nanoparticles (NPs) endow the ternary hybrids with superparamagnetism (21.42 emu g^?1), facilitating catalysts to be separated from the reaction system. rGO could provide electron transfer pathways, enhancing catalytic activity. More interestingly, GO and Ag⁺ could behave as oxidants to oxidize Fe²⁺ for the in situ assembly of Fe₃O₄‐Ag/rGO without any addition of reductant/oxidant or organic solvents, and AgNPs endow the ternary hybrids with excellent catalytic behaviour. Meaningfully, the bioinspired process enables the ternary hybrids to possess more abundant micro?/nanopores, larger surface area, and more amorphization. They exhibit exceptional catalytic performance, and could be recycled with excellent activity by means of convenient magnetic separation (at least 7 times). Moreover, the ternary hybrids could degrade methylene blue under UV light due to different valence states of Fe in Fe₃O₄. Therefore, the proposed bioinspired assembly and structure design for hierarchical catalysts would pave a promising way to assemble other catalysts.