Biomass Inspired Nitrogen Doped Porous Carbon Anode with High Performance for Lithium Ion Batteries

Ginkgo leave, a naturally abundant resource, has been successfully employed as the raw material to prepare nitrogen doped porous carbon (NDPC) materials. The preparation of the porous carbon does not involve assistance of any activation or template technique. The as‐obtained NDPC shows favorable features for electrochemical energy storage, which can not only provide multiple sites for the storage and insertion of Li ions, but also facilitate rapid mass transport of electrons and Li ions. As a result, the NDPC when evaluated as an anode material for lithium ion batteries delivers high reversible capacity (505 mAh·g^?1 at 0.1 C), excellent rate capability (190 mAh·g^?1 at 10 C). These favorable properties suggest that the NDPC can be a promising anode material for lithium ion batteries (LIBs).     

一种用于多叶准直器适形放疗的剂量算法研究

描述了一种用于多叶准直器适形放疗的剂量计算方法。 在不同大小的方野和非规则野照射情况下, 将此方法得到的剂量分布与微分卷积法计算得到的剂量分布进行了精度验证。 结果表明， 这种算法具有较高的剂量精度和较快的计算速度, 因此可在适形放疗中用作MLC适形野的自动生成。 A dose calculation algorithm for MLC based conformal radiotherapy is described in this paper. The algorithm is formulated by the coordinate of MLC leaves. Verification on the algorithm is made by comparing the dose distributions generated by this algorithm with that generated by a Differential Convolution Superposition algorithm for various regular and irregular fields. The results demonstrate that the present algorithm has suitable accuracy and high computational efficiency, thus it could be useful for the treatment planning process in MLC based conformal radiotherapy, where the workload for interactively or automatically designing the shapes of MLC is heavy.     

Group divisible ‐packings with any minimum leave

A decomposition of , the complete n‐partite equipartite graph with a subgraph L (called the leave) removed, into edge disjoint copies of a graph G is called a maximum group divisible packing of with G if L contains as few edges as possible. We examine all possible minimum leaves for maximum group divisible ‐packings. Necessary and sufficient conditions are established for their existences.     

Neutron diffraction evidence for anion sublattice disordering in alkali earth fluorides at high temperatures

High temperature powder neutron diffraction studies of calcium, strontium and barium fluorides indicate that there are large thermal motions associated with the anions. This suggests that the anion sublattice in these compounds with the fluoride structure may disorder at temperatures below the melting points. In S:F₂ this disordering appears at about 1370 K and for BaF₂ at about 1300 K. This is in good agreement with transitions of 1440 K and 1240 K, predicted from thermodynamic data.     

人参茎叶挥发油中含氧化合物的分离与结构鉴定

组成鉴定;人参茎叶挥发油中含氧化合物的分离与结构鉴定     

Electric field gradients in EuScFe garnets

The electric quadrupole interactions at the octahedral, tetrahedral, and dodecahedral sites in the Eu_3?ySc_2+yFe₃O₁₂ (0 ≤ y ≤ 0.5) garnet system were studied with ⁵⁷Fe and ¹⁵¹Eu Mössbauer spectroscopy. The electric field gradient tensor at the three sites was calculated using a monopole-point-dipole model. It is shown that the dipole contribution to the electric field gradient tensor is not negligible even for very small values of the oxygen dipole polarizability. The importance of the overlap and second-order 4f contributions is discussed.