The smart precursors of energetic–energetic cocrystals from eutectic precursors

The selected 18 energetic compounds were theoretically investigated by using the density functional theory（DFT） quantum mechanical code,DMol3,and the Hansen solubility parameters（HSPs） analyses.The results showed that 4-nitrotoluene,4-nitrophenol,N N0-dimethyl-N N0-diphenylurea and N N0-diethyl-N N0-diphenylurea contain relatively electron-rich aromatic rings.Four satisfactory energetic precursors with electron-rich rings were quickly and effectively found by electrostatic potential（ESP）surfaces and HSPs analyses.The results also indicated that the absolute value of the lowest unoccupied molecular orbital（LUMO） of the energetic precursors with electron-rich rings often was less than3.00 eV,and the absolute value of LUMO of the energetic precursors with electron deficient rings was often more than 3.00 eV.Additionally,we found that with at least two eutectic points was a prerequisite for two precursors to form a cocrystal.     

基于Nafion膜的柱层析纯化过程的电化学在线检测器

电化学检测一般需加入电解质以降低溶液电阻,为解决天然药在层析纯化检测中无支持电解质的问题,研制了一种以液体石蜡石墨为工作电极的电化学在线检测器,利用了Nafion N-324膜固体酸的性质,在不额外添加电解质的情况下,直接获得了杨梅素80％乙醇溶液(V/V)的循环伏安图.在恒电位0.53 V下,实现了对层析液中有效物质的电化学在线检测.在2×10-5～1×10-2 mol/L范围内,峰面积(A)与杨梅素浓度(C)存在线性关系.线性方程为A=2.7227C+0.4341.r=0.9976.在恒电位0.62 V无支持电解质的80％乙醇溶液中,对30％竹叶黄酮粗提品纯化过程的在线检测,获得了时间-电流信号的流出曲线,可用于实际样品分析.     

100MeV强流质子回旋加速器高频腔公差研究

针对中国原子能科学研究院正在设计的100MeV强流质子回旋加速器, 研究并提出高频腔公差. 高频腔的误差包括加工安装的误差和重力引起的D板变形. 加工安装误差的存在干扰束团的径向和轴向运动, 用理论分析和数值模拟相结合的方法给出加工安装的公差; D板的重力变形引起加速间隙的轴向错位从而使束团产生轴向的相干振荡, 计算结果表明目前结构的D板变形在允许范围内.     

100MeV强流质子回旋加速器高频腔公差研究

针对中国原子能科学研究院正在设计的IOOMeV强流质子回旋加速器,研究并提出高频腔公差.高频腔的误差包括加工安装的误差和重力引起的D板变形.加工安装误差的存在干扰束团的径向和轴向运动,用理论分析和数值模拟相结合的方法给出加工安装的公差;D板的重力变形引起加速间隙的轴向错位从而使束团产生轴向的相干振荡,计算结果表明目前结构的D板变形在允许范围内     

硝基咪唑化合物结构与性质的理论研究

采用密度泛函理论B3LYP方法在6-311G(d,p)水平上, 对10种硝基咪唑化合物进行了理论计算: 几何优化结果显示所有化合物均无虚频, 为势能面上的稳定结构. 基于自然键轨道理论和三维静电势图, 分析了稳定结构的成键情况、咪唑环上的共轭性及硝基咪唑化合物的反应性. 理论估算了10种化合物的标准气态生成热和密度, 最后采用VLW方程计算了这些化合物的爆速、爆压, 其爆速在8.7和9.5 km/s之间. 结果表明: 咪唑环上有一定的芳香性, 所设计的系列硝基咪唑化合物能量高, 其中三硝基咪唑化合物是最有潜力的含能材料候选物.     

2-取代-5,5-二硝基嘧啶-4,6-二酮的合成和反应

研究了2-取代嘧啶-4,6-二酮的硝化反应, 产物为2-取代-5,5-二硝基嘧啶-4,6-二酮(3), 收率＞80%, 3与亲核试剂反应形成开环产物. 2-位取代基为烷基时, 嘧啶环5-位和侧链的α-位都发生反应, 当取代基为甲基时, 硝化产物为2-(二硝基亚甲基)-5,5-二硝基嘧啶-4,6-二酮(1), 1的水解产物为1,1-二氨基-2,2-硝基乙烯 (FOX-7) 和二硝基甲烷(2). 2-位取代基为羟基时, 硝化产物为5,5-二硝基巴比妥酸(7b), 7b水解可制得偕二硝基乙酰基脲(9b), 9b与KOH作用生成偕二硝基乙酰基脲钾盐(10b)和二硝基甲烷钾盐(11). 2-位取代基为氨基时, 硝化开环生成偕二硝基乙酰基胍(9a), 9a与KOH作用生成偕二硝基乙酰基胍钾盐(10a)和11. 当2-位无取代基时, 硝化产物无法分离, 结构推测为7c. 考察了亲核试剂对FOX-7收率的影响并对FOX-7的三种合成方法进行了评价, 对反应机理进行了探讨.     

1,1-二氨基-2,2-二硝基乙烯的合成与性能研究

以2-甲基嘧啶-4,6-二酮为原料, 通过硝化和水解过程合成出FOX-7 (1,1-二氨基-2,2-二硝基乙烯), 经IR, MS, NMR和元素分析鉴定了其结构, 并对影响得率的主要因素进行了简要分析. 重结晶提纯后培养合成产物的单晶, 用四圆衍射仪对其进行了结构解析, 得到了合成产物的晶体学数据. 测试了FOX-7的电火花感度和落锤感度, 并同RDX (1,3,5-三硝基-1,3,5-三氮杂环己烷)、HMX(环四甲撑四硝胺)以及TATB(三氨基三硝基苯)进行了对比, 结果表明FOX-7的感度要低于RDX, 但较TATB差. 同时对原始样品和重结晶FOX-7的外观形貌和热性质进行了测试, 并对变化情况进行了说明, 发现FOX-7的外观形貌和热性质可以进一步改善和优化.     

Influence of temperature on strain-induced polarization Coulomb field scattering in AIN/GaN heterostructure field-effect transistors

Electron mobility scattering mechanism in AlN/GaN heterostuctures is investigated by temperature-dependent Hall measurement, and it is found that longitudinal optical phonon scattering dominates electron mobility near room temperature while the interface roughness scattering becomes the dominant carrier scattering mechanism at low temperatures （~ 100 K）. Based on measured current-voltage characteristics of prepared rectangular AlN/GaN heterostructure field-effect transistor under different temperatures, the temperature-dependent variation of electron mobility under different gate biases is inves- tigated. The polarization Coulomb field （PCF） scattering is found to become an important carrier scattering mechanism after device processing under different temperatures. Moreover, it is found that the PCF scattering is not generated from the thermal stresses, but from the piezoelectric contribution induced by the electrical field in the thin A1N barrier layer. This is attributed to the large lattice mismatch between the extreme thinner AlN barrier layer and GaN, giving rise to a stronger converse piezoelectric effect.     

Performance analysis of GaN-based high-electron-mobility transistors with postpassivation plasma treatment

AlGaN/GaN high-electron-mobility transistors(HEMTs)with postpassivation plasma treatment are demonstrated and investigated for the first time.The results show that postpassivation plasma treatment can reduce the gate leakage and enhance the drain current.Comparing with the conventional devices,the gate leakage of Al Ga N/Ga N HEMTs with postpassivation plasma decreases greatly while the drain current increases.Capacitance-voltage measurement and frequencydependent conductance method are used to study the surface and interface traps.The mechanism analysis indicates that the surface traps in the access region can be reduced by postpassivation plasma treatment and thus suppress the effect of virtual gate,which can explain the improvement of DC characteristics of devices.Moreover,the density and time constant of interface traps under the gate are extracted and analyzed.     

Roles of Electron Hopping on Orbital Ordering for Vanadium Spinels

We investigate the orbital ordering quantitatively for the spinel systems RV₂O₄ (R=Mg, Zn, Cd) in the viewpoint of single-ion physics through the method of diagonalization. Through the quantitative calculation, it is found that the spin-orbit (SO)coupling and the Jahn-Teller (JT) effect enable the orbital ordering under the conditions of negligible electron hopping among different V³⁺ sites. For the systems RV₂O₄, the electron hopping is implied to be observable from the energy gap in conductivity, so the orbital ordering of RV₂O₄ cannot be induced by the SO coupling and JT effect at definite temperature, which is on contrary to the conclusions in [Phys. Rev. Lett. 93 (2004) 157206].