Sufficient Conditions for Amalgamated 3-Manifolds to be ∂-Irreducible∗

In this paper, the authors give some sufficient conditions for an amalgamated 3-manifold along a compact connected surface F with boundary to be ?-irreducible in terms of distances between some kinds of vertex subsets of the curve complex and the arc complex of F.     

复合材料柔软性对倒金字塔微结构阵列传感器性能的影响

采用模压成型方法制备了2种柔软性不同的热塑性聚氨酯/短切碳纤维/碳纳米管(TPU/SCF-CNT)复合材料复制物, 其表面上具有倒金字塔微结构阵列, 内部有SCF与CNT共同构成的导电通路. 将复合材料复制物和相应的复合材料平整片封装成柔性传感器. 结果表明, 压力作用下传感器内复制物和平整片之间的接触电阻因倒金字塔底棱的形变而显著降低. 对使用柔软性较高的复合材料封装的传感器, 虽然其相对迟滞稍大, 但压力作用下倒金字塔底棱形变量较大, 且复制物和平整片内导电通路增加量较大, 因此其在0~2.5 kPa的线性区内具有较高的灵敏度(0.32 kPa^?1). 制备的2种传感器均具有快速响应特性, 且能在500 s(约1580次)的循环压缩/释放测试(峰值压力约3 kPa)中保持较稳定的电阻响应. 研究表明, 利用模压成型的表面倒金字塔结构复合材料复制物封装成的柔性压力传感器具有良好的传感性能.     

Ru、Rh、Pd掺杂GaSb的电子结构和光学性质

运用第一性原理计算方法研究了过渡族金属TM(TM=Ru、Rh、Pd)掺杂GaSb的电子结构和光学性质,结果表明:TM掺杂GaSb主要以TM替代Ga(TM @Ga)缺陷存在,并可增强GaSb半导体材料对红外光区光子的响应,使体系光学吸收谱的吸收边红移;TM@Ga所引入的杂质能级分布于零点费米能级附近,这极大地增强了体系的介电性能,促进了电子-空穴对的产生和迁移,因而提升了掺杂体系的光电转换效率;Ru 掺杂对GaSb光学性质的改善最为明显,当掺杂浓度为6.25%(原子数分数)且均匀掺杂时,Ru掺杂GaSb体系对红外光区光子的吸收幅度最大,有效提升了GaSb光电转换效率和光催化活性。     

2-氨基嘧啶对铜的缓蚀机理

利用动电位极化曲线、线性极化、X射线光电子能谱(XPS)、X射线俄歇能谱(X-AES)和表面增强拉曼散射(SERS)研究2-氨基嘧啶(2-AP)对金属铜的缓蚀作用。结果表明: 在含Cl~-离子的酸性介质中, 2-AP是铜的有效缓蚀剂; 随着介质pH值的增加, 2-AP的缓蚀能力降低。2-AP缓蚀能力随pH值明显变化的原因在于只有在酸性介质中, 质子化了的2-AP分子、Cl~-离子和铜表面原子(或离子)才可能形成保护作用强的多聚配合物膜。     

Effects of group-delay difference on ultrashort pulse propagation in an active nonlinear LPFG

The effects of group-delay difference in an active nonlinear long-period fiber grating (LPFG) made in an erbium-doped amplifying fiber (EDF) are investigated by proposing a general model that include the effects of detuning, group-delay difference, gain saturation, gain bandwidth and Kerr nonlinearity. In particular, we observe a new feature caused by the interaction between the group-delay difference and the gain bandwidth: the pulse breakup effect due to the group-delay difference can be suppressed by the finite bandwidth of the linear gain.     

When closed graph manifolds are finitely covered by surface bundles over S 1

The problem of deciding whether a graph manifold is finitely covered by a surface bundle over the circle is discussed in this paper. A necessary and sufficient condition in term of the solutions of a certain matrix equation is obtained, as well as a necessary condition which is easy to compute. Our results sharpen and extend the earlier results of J. Leucke-Y. Wu, W. Neumann, and S. Wang-F. Yu in this topic. Supported in part by NSFC     

Unstabilized and uncritical self-amalgamation along essential subsurfaces

Suppose V ∪_S W is a strongly irreducible Heegaard splitting of a compact connected orientable 3-manifold M and F_1 and F_2 are pairwise disjoint homeomorphic essential subsurfaces in ?_V. In this paper,we give a sufficient condition such that the self-amalgamation of V ∪_S W along F_1 and F_2 is unstabilized and uncritical.     

Electronic structure and magnetic properties of metastable SmCo_7 compound

1 Introduction The rare-earth transition-metal intermetallic compounds have been widely investi-gated for many years, among them the Sm-Co series compounds with 1:5 and 2:17 crys-tal structures. These compounds have been used as sintered and bonded permanent magnets since the 1960s[1,2]. Interest recently has been focused on the TbCu7-type struc-ture Sm-Co intermetallic compounds with a strong uniaxial magnetocrytalline anisot-ropy and a low temperature coefficient (β = ?0.11%)[3―6] due t…     

2-Compressible non-Heegaard surfaces in small 3- manifolds

In the present paper, we investigate the non-Heegaard 2-compressible surfaces in small 3-manifolds, and show that such surfaces have some good properties.     

Hydrogenic impurity states in zinc-blende InGaN quantum dot

Within the framework of effective-mass approximation, the binding energy of a hydrogenic donor impurity in a zinc-blende (ZB) InGaN/GaN cylindrical quantum dot (QD) is investigated using a variational procedure. Numerical results show that the donor binding energy is highly dependent on impurity position and QD size. The donor binding energy E_b is largest when the impurity is located at the center of the QD. The donor binding energy is decreased when the dot height (radius) is increased.