高压下氢化锂晶体中的离子间力与结合能公式的原子分子设计

本文提出一种利用材料Hugoniot数据研究高压下离子晶体中微观离子状态及其离子间排斥作用势的新方法。对氢化锂晶体进行研究时,我们得到Li~+和H~-离子之间排斥作用势函数,结果表明文献〔1〕中提出的离子压缩效应具有客观性。     

氯化钠团簇的形成规律与结合能计算

当离子蒸气冷凝形成团簇时，其结构表现出特定的规律。文中对不同大小不同形状的氯化钠团簇结构与结合能进行了计算，以求揭示离子蒸气冷凝形成团簇的一些规律，并与实验结果进行对照。     

Manganese(I)-Catalyzed Regioselective C−H Allenylation: Direct Access to 2-Allenylindoles

A Mn^I-catalyzed regioselective C−H allenylation is reported that allows a broad range of 2-allenylindoles to be synthesized regioselectively on a gram scale under simple conditions. Notably, a highly efficient chirality transfer was observed (up to 93 % ee) in this transformation. This procedure was further found to allow, for the first time, the direct preparation of ketones by Mn^I-catalyzed C−H activation. Mechanistic investigations revealed that the precoordination of the oxygen atom to the manganese center as well as the congested tertiary carbon atom in the propargylic carbonates play a crucial role.     

Effects of graft length and density of well‐defined graft polymers on the thermoresponsive behavior and self‐assembly morphology

A series of well‐defined thermoresponsive graft polymers with different lengths and graft densities, poly(glycidyl methacrylate)‐graft‐poly(N‐isopropylacrylate) (PGMA‐g‐PNIPAM), were successfully prepared by combination of controlled/living free radical polymerization and click chemistry. Effects of grafting length and density on the thermoresponsive behavior, aggregating mean diameter, and self‐assembly morphology are systematically investigated. The thermosensitive characteristics of graft polymers in aqueous solution prove that the length and graft density had positive co‐relationship with the lower critical solution temperature value and mean diameter of micelles as well as the size distribution, while the effect of graft length of polymers is more significant than that of density. Transmission electron microscopy analysis shows that the conformations of PGMA₄₅‐g‐PNIPAM₂₀ and PGMA₄₅‐g‐PNIPAM₄₆ with longer length and bigger grafting density in aqueous solutions are spherical nanoparticles with the increasing trend of the diameters, while that of PGMA₄₅‐g‐PNIPAM_{(73, 50%)} shows a spherical‐like morphology, which indicates that the graft length and density have a significant effect on the mean diameter of micelle but not on the self‐assembly morphology. These results reveal that to obtain desired thermoresponsive behavior and self‐assembly morphology of functional polymers, it is essential to design and fabricate the structure of graft polymers with proper length and graft density. © 2014 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2014 , 52, 2442–2453     

梯级溃坝洪水洪峰增强机制

我国在多条河流上修建了大量梯级水库, 梯级坝溃决诱发洪水大大超过单坝溃决洪水洪峰, 因此亟需加深对梯级坝溃决洪水洪峰增强机制的认识. 本文建立了梯级坝溃决洪水演进过程的一维浅水动力学模型, 发展了一套能捕捉激波、干湿边界和保平衡结构的数值求解方法, 通过大量算例, 系统研究了梯级坝溃决洪水演进过程的质量转化和能量转化机制. 研究结果表明, 梯级溃决中, 上游溃决诱发的洪水大大增大下游水库的质量和动量, 形成一个带动量的水塔, 同时在尾部残留一个动量较大的射流, 不断补充下游坝体溃决后水塔的质量和动量, 持续维持洪峰高度. 根据该射流-水塔机制, 建立了梯级坝溃决洪水演进过程对应的射流-水塔单坝溃决洪水过程等效模型, 该等效模型基本反映了梯级坝溃决诱发洪水的洪峰过程, 并成功预测了多个坝间距为百公里量级的梯级坝溃决洪水洪峰高程和流量, 可望为流域防洪和梯级坝设计提供理论依据.      

聚合物纳米复合电介质

聚合物纳米复合材料能够发挥纳米材料在电、磁、光等方面的优越性,也具有聚合物的易成型等方面的优点,正成为电介质领域研究的热点.本文综述了聚合物纳米复合材料在介电性能方面的研究概况,主要涉及了电导、介电强度与空间电荷、介电常数、介电损耗以及局部放电等方面的研究.最后展望了今后的研究方向.     

Mo掺杂Mn4Si7的光电性质的第一性原理计算

采用基于密度泛函理论(DFT)的第一性原理计算方法,计算了Mn4Si7及Mo掺杂Mn4Si7的电子结构和光学性质.计算结果表明Mn4 Si7的禁带宽度Eg=0.804 eV,Mo掺杂Mn4Si7的禁带宽度Eg=0.636 eV.掺杂使得Mn4 Si7费米面附近的电子结构发生改变,导带底由Γ点转移为Y点向低能方向下偏移,价带顶向高能方向上偏移,带隙变窄.计算还表明Mo掺杂Mn4Si7使介电函数、折射率、吸收系数及光电导率等光学性质增加.     

重氢原子进入钛晶体中引起的晶体结构转变与电解重水过程中“过热”现象的关系

对重氢原子进入钯或钛晶体中可能引起常温核聚变的机理探讨与实验研究结果，已在文献［１］中作了报导。后来又对钛阴极材料，在使用前后进行了Ｘ射线结构分析。发现在电解过程中发生过“过热”现象的钛阴极材料的晶体结构由原来的密排六方结构转变为立方结构，而没有发生“过热”现象的钛阴极材料的晶体仍然保持电解前的密排六方结构     

Smallest g -supersolution with constraint

In this paper the existence and uniqueness of the smallest g-supersolution for BSDE is discussed in the case without Lipschitz condition imposing on both constraint function and drift coefficient in the different method from the one with Lipschitz condition. Then by considering (ξ, g) as a parameter of BSDE, and (ξ ^α, g ^α) as a class of parameters for BSDE, where α belongs to a set , for every there exists a pair of solution {Y ^a, Z^a} for the BSDE, the properties of which is also a solution for some BSDE is studied. This result may be used to discuss optimal problems with recursive utility. This work was supported by NSFC (79790130)     

The Tunneling Radiation Characteristics of Kerr-Newman de Sitter Black Hole

The strictly thermal spectrum in dragging coordinate system and the tunneling radiation characteristics of stationary axisymmetry Kerr-Newman de Sitter black hole is studied. The result shows that the tunneling rates at the event and cosmological horizon are related to the change of Bekenstein-Hawking entropy and that the factual radiation spectrum is not strictly pure thermal. Thus an exact correction to the Hawking thermal spectrum is present.