影响TiO2薄膜光催化降解亚甲基蓝的因素

 用中频交流反应磁控溅射技术制备了具有良好光催化性能的TiO2薄膜,考察了紫外光源、反应器和溶液浓度对亚甲基蓝溶液光催化降解特性的影响. 结果表明,紫外光源对TiO2薄膜光催化降解性能有较大的影响; 在计算光催化降解速率时应充分考虑光解和光氧化的影响. 低压汞灯TUV为光催化降解的较好选择. 动态反应系统可以有效避免光解,显著提高光催化反应速度. TiO2薄膜具有很好的光催化性能,且性能稳定.     

时均流驱动热声制冷研究进展

时均流驱动热声制冷是热声领域的全新方向,依据该原理工作的热声制冷系统能够利用风能获得制冷效应,完全没有运动部件,为风能利用提供了一种新思路。文中详细介绍了时均流诱导声振荡的工作机理以及时均流驱动热声制冷的最新研究进展,并对该领域的研究进行了展望。     

PVK/C_(60)组合体系薄膜的拉曼光谱和荧光光谱研究

我们采用物理喷束淀积技术制备了Ｃ６０、Ｃ７０及聚乙烯咔唑ＰＶＫ／Ｃ６０的混合和分层薄膜，拉曼光谱的测量表明，这种技术所制备的富勒烯薄膜中，富勒烯的笼型结构仍保持完整，而在ＰＶＫ／Ｃ６０组合薄膜中，拉曼光谱及荧光光谱测量表明：在ＰＶＫ和Ｃ６０分子之间存在激发传递过程，在混合膜中，这种激发传递过程要明显强于分层组合薄膜。     

A novel method of high speed frequency shift keying modulation in mm waves

To place a high speed switching diode in the cavity of the mm wave scillator has the behavior equivalent to an inductive post. The on-and-off switching of the diode will give rise to the change of inductance, hence the change of parameters of the cavity, and the osaillating frequency. In this article, the basic principle and the measured result are given. It is found that this is an efficient method in high speed frequency shift keying (FSK) modulation for a mm wave transmitter in communication.     

Cumulative yields of127gSn and128Sn in the spontaneous fission of252Cf

The potteries found on the Tremiti Isles (Italy, Adriatic Sea) have been characterized through their trace elements content. The goal of the work was to find out the number of ore deposits that supplied the clay used to manufacture the pottery. Neutron activation analysis has been employed for trace elements content determinations; the results have been statistically evaluated, clusterized and discussed.     

水溶性β-内酰胺对映体在β-环糊精键合固定相上的手性分离

本文介绍在β-环糊精键合固定相上水溶性单环β-内酰胺类化合物对映体的手性分离,考查了流动相组成和色谱柱温度对容量因子k′,对映体选择性α和峰分离度P的影响,比较了具有不同取代基的β-内酰胺样品的对映体的分离。     

Single-atom nickel terminating sp2 and sp3 nitride in polymeric carbon nitride for visible-light photocatalytic overall water splitting

Polymeric carbon nitride (PCN) has been widely used as a metal-free photocatalyst for solar hydrogen generation from water. However, rapid charge carrier recombination and sluggish water catalysis kinetics have greatly limited its photocatalytic performance for overall water splitting. Herein, a single-atom Ni terminating agent was introduced to coordinate with the heptazine units of PCN to create new hybrid orbitals. Both theoretical calculation and experimental evidence revealed that the new hybrid orbitals synergistically broadened visible light absorption via a metal-to-ligand charge transfer (MLCT) process, and accelerated the separation and transfer of photoexcited electrons and holes. The obtained single-atom Ni terminated PCN (PCNNi), without an additional cocatalyst loading, realized efficient photocatalytic overall water splitting into easily-separated gas-product H₂ and liquid-product H₂O₂ under visible light, with evolution rates reaching 26.6 and 24.0 μmol g⁻¹ h⁻¹, respectively. It was indicated that single-atom Ni and the neighboring C atom served as water oxidation and reduction active sites, respectively, for overall water splitting via a two-electron reaction pathway.

Single-atom Ni terminating agent is introduced to coordinate with sp² or sp³ N atoms in the heptazine units of PCN, realizing visible-light photocatalytic overall water splitting to H₂O₂ and H₂ without additional cocatalyst.     

Measurement of the half-life of79Se using a radiochemical method

The half-life of⁷⁹Se, a long-lived fission product nuclide, has never been measured accurately. The value quoted in the literature is an upper limit, 6.5·10⁴ y, measured in 1949. In the present work we measured accurately the half-life of⁷⁹Se to be (4.8±0.4)·10⁵ y using a radiochemical method.     

对甲苯磺酸催化合成乳酸异戊酯

报道了对甲苯磺酸在异戊醇和乳酸酯化反应中的应用 ,讨论了合成条件。实验表明其催化活性良好。     

A polynomial algorithm to compute the minimum degree spanning trees of directed acyclic graphs with applications to the broadcast problem

In this paper, we focus on the directed minimum degree spanning tree problem and the minimum time broadcast problem. Firstly, we propose a polynomial time algorithm for the minimum degree spanning tree problem in directed acyclic graphs. The algorithm starts with an arbitrary spanning tree, and iteratively reduces the number of vertices of maximum degree. We can prove that the algorithm must reduce a vertex of the maximum degree for each phase, and finally result in an optimal tree. The algorithm terminates in O(mnlogn) time, where m and n are the numbers of edges and vertices of the graph, respectively. Moreover, we apply the new algorithm to the minimum time broadcast problem. Two consequences for directed acyclic graphs are: (1) the problem under the vertex-disjoint paths mode can be approximated within a factor of of the optimum in O(mnlogn)-time; (2) the problem under the edge-disjoint paths mode can be approximated within a factor of O(Δ^*/logΔ^*) of the optimum in O(mnlogn)-time, where Δ^* is the minimum k such that there is a spanning tree of the graph with maximum degree k.