高效液相色谱-质谱联用法测定烟草中茉莉酸

采用高效液相色谱-质谱(HPLC-MS)联用法检测烟草中茉莉酸(JA)含量。样品研磨均质后经丙酮和柠檬酸萃取,离心分离,取上清液,氮气吹去丙酮后用乙醚萃取。经氨丙基固相萃取柱净化,吹干后用色谱流动相溶解,过0.45μm有机滤膜。利用高效液相色谱-质谱联用电喷雾负离子,选择离子监测模式进行检测,内标法定量。结果表明,待测样品JA浓度范围在5～1 000ng/mL之间,标准曲线具有良好的线性关系。方法检出限(S/N≥3)是2.0ng/mL。平均回收率为80.6%～101.1%,相对标准偏差为3.5%～14.6%。应用该方法检测烟草打顶与不打顶植株之间JA含量的差异,结果比较理想。     

含乙酰氧肟酸配体的席夫碱钒配合物的合成、结构及其抑制幽门螺旋杆菌脲酶研究

本文合成了2个新的含乙酰氧肟酸配体的席夫碱钒配合物,[V^ⅢL¹(HAHA)](1)和[V^ⅤOL²(AHA)](2),其中L¹为N,N’-二(5-甲基水杨基)乙烷-1,2-二胺的二价阴离子,L²为2-{[2-(2-羟乙基氨基)乙亚胺基]甲基}-6-甲基苯酚的一价阴离子,HAHA和AHA分别为乙酰氧肟酸的一价和二价阴离子,通过物理-化学方法以及单晶X-射线衍射表征了它们的结构。在每个化合物中,V原子都采取八面体配位构型。本文还研究了配合物的热稳定性以及其对幽门螺旋杆菌脲酶的抑制活性。在浓度为100μmol·L^-1时,配合物1和2对脲酶的抑制率分别为37.2%和81.5%,其中配合物2的IC₅₀值为21.5μmol·L^-1。分子对接研究表明配合物2与脲酶活性中心存在有效的作用力。     

北魏墓彩绘陶俑颜料的显微拉曼光谱分析

利用拉曼光谱对洛阳地区两座北魏墓出土陶俑的彩绘颜料进行了分析, 与标准颜料样品的拉曼光谱相比较, 识别出了陶俑所使用的红色、黑色、白色和蓝色颜料的显色成分。研究结果表明, 显微拉曼光谱分析技术非常适合对古墓葬彩绘陶俑进行成分分析。     

Al原子在Pb基底上的沉积过程研究

利用分子动力学方法模拟了Al原子在Pb基底上的沉积过程. 对Al原子在Pb基底(001)面上沉积的形态与Pb原子在Al(001)基底上沉积的形态做了比较. 由于界面间势垒的不同, 两个体系界面间的形态有明显的差异. 分析了基底温度、基底晶面指向、沉积原子的入射动能对界面间原子混合的影响. 模拟结果显示: 随着基底温度升高, 基底原子的可移动性大大增加, 与沉积原子发生较大程度的混合; 入射能的改变对界面间原子的混合影响很小; 基底表面取不同的晶格指向时, 基底与沉积原子间的混合行为也有明显的不同. 利用径向分布函数分析了沉积原子的入射能对薄膜中原子排列有序性的影响. 较高入射能对应更有序的薄膜结构; 由径向分布函数的结构可以推测Al原子在Pb(001)基底表面沉积时界面间可能有金属间化合物生成. 关键词： Pb/Al体系 沉积过程 分子动力学 入射能     

用扩散蒙特卡罗方法研究BH2, B(OH)2, BCl2和BCl的键离解能

采用扩散蒙特卡罗(DMC)方法计算了BH₂, B(OH)₂, BCl₂和BCl的HB-H和HOB-OH的键离解能, 同时也研究了轨道选择和Backflow变换对DMC计算结果的影响． 在Slater-Jastrow DMC(SJ-DMC)计算方法中,当采用B3PW91轨道时得到的HB-H和HOB-OH键离解能分别是359.1±0.12和98.2±0.12 kJ/mol;用B3LYP SJ-DMC计算键离解能得到了与用B3PW91 SJ-DMC方法类似的结果．通过BF-DMC(即在DMC中引入backflow修正)计算得到的HB?H键离解能为369.6±0.12 kJ/mol,也得到了更加接近实验值的HOB-OH键离解能为446.0±1.84 kJ/mol．由DMC的计算结果可以断定HB?H的键离解能的实验值为375.8 kJ/mol．另外还给出了BCl2和BCl的键离解能的计算结果.     

Efficient entanglement purification in quantum repeaters

We present an efficient entanglement purification protocol (EPP) with controlled-not (CNOT) gates and linear optics. With the CNOT gates, our EPP can reach a higher fidelity than the conventional one. Moreover, it does not require the fidelity of the initial mixed state to satisfy F>1/2. If the initial state is not entangled, it still can be purified. With the linear optics, this protocol can get pure maximally entangled pairs with some probabilities. Meanwhile, it can be used to purify the entanglement between the atomic ensembles in distant locations. This protocol may be useful in long-distance quantum communication.     

First-principles investigation on the elastic stability and thermodynamic properties of Ti2SC

Using Vanderbilt-type plane-wave ultrasoft pseudopotentials within the generalized gradient approximation（GGA） in the frame of density functional theory（DFT）,we have investigated the crystal structures,elastic,and thermodynamic properties for Ti2SC under high temperature and high pressure.The calculated pressure dependence of the lattice volume is in excellent agreement with the experimental results.The calculated structural parameter of the Ti atom experienced a subtle increase with applied pressures and the increase suspended under higher pressures.The elastic constants calculations demonstrated that the crystal lattice is still stable up to 200 GPa.Investigations on the elastic properties show that the c axis is stiffer than the a axis,which is consistent with the larger longitudinal elastic constants（C 33,C 11） relative to transverse ones（C 44,C 12,C 13）.Study on Poisson＇s ratio confirmed that the higher ionic or weaker covalent contribution in intra-atomic bonding for Ti2SC should be assumed and the nature of ionic increased with pressure.The ratio（B/G） of bulk（B） and shear（G） moduli as well as B/C 44 demonstrated the brittleness of Ti2SC at ambient conditions and the brittleness decreased with pressure.Moreover,the isothermal and adiabatic bulk moduli displayed opposite temperature dependence under different pressures.Again,we observed that the Debye temperature and Gru篓neisen parameter show weak temperature dependence relative to the thermal expansion coefficient,entropy,and heat capacity,from which the pressure effects are clearly seen.     

变截面微小通道传热特性的研究

为研究变截面微小通道的流动和传热特性,设计了9种不同微小尺度的变截面通道。采用实验研究的方法,得出了流体在变截面微小通道中的传热特性以及与常规尺度通道的差异。分别比较了通道的进出口宽度比、通道的高宽比对变截面、微小尺度通道传热特性的影响。根据实验结果,得到了描述水在变截面微小通道中的流动及传热特性的无量纲关联式。     

敏锐的科学思想和崇高的人文精神——纪念劳厄诞辰130周年

简要地介绍了劳厄的卓越科学贡献及其产生的深远影响，以及他爱憎分明的崇高品德等，并由此揭示了这位伟大的科学大师所留给后人的深刻启示．     

A New One-dimensional Dicyanamide Bridged Zinc(II) Complex Containing Nitronyl Nitroxide Radicals:Synthesis,Crystal Structure and Magnetic Properties

A new one-dimensional dicyanamide bridged zinc(II) complex containing nitronyl nitroxide radicals Zn(NO3)(NIT-1'-MeBzIm)(dca)n·(H2O)n(NIT-1'-MeBzIm = 2-{2'-(l'-me-thyl)benzimidazolyl}-4,4,5,5-tetramethylimidazoline-1-oxyl-3-oxide, dca = dicyanamide anion) has been prepared and structurally characterized by single-crystal X-ray diffraction.The complex crystallizes in triclinic, space group P1, with a = 7.428(3), b = 9.839(3), c = 16.708(6), α = 93.270(4), β = 101.642(4), γ = 100.632(4)°, C17.5H21N8O5.5Zn, Mr = 496.79, V = 1169.7(7) 3, Dc = 1.411 g/cm3, μ(MoKα) = 1.096 mm-1, Z = 2, F(000) = 512, R = 0.0583 and wR = 0.1663 for 4295 observed reflections with I > 2σ(I).X-ray analysis reveals that the zinc(II) ion is six-coordinated with a distorted octahedral geometry.These units develop as 1D species where dicyanamide ligands bridge zinc(II) ions.In addition, molecules are linked by π-π piling interactions to form 1-D double-chains.Magnetic investigation indicates that the weak intramolecular interactions are antiferromagnetic with J =-0.27 cm?1, where the spin Hamitonian is defined as H =-2∑i,jJi,jSiS within the complex.