N’-苄基酰腙分子的氮-氮键旋转位阻及分子构象

采用动态核磁共振波谱(DNMR)和密度泛函理论(DFT)对N'-苄基酰腙化合物进行构象研究. 实验和理论计算表明, 1H NMR图谱中三组不同质子的双峰裂分是由N—N键旋转位阻造成的, 而这三个双峰裂分的化学位移差异随温度升高而减小. 通过模拟化学位移差异与温度的关系, 得到了交换速率常数, 采用Eyring方程计算出N—N键旋转位阻. 提出顺式和反式共存的模型来分析酰胺质子信号分裂的原因, 并利用DFT计算得出优化的异构体构象及其最低能量. 端甲基质子和次甲基质子信号裂分也来源于N—N键旋转受阻. N'-苄基酰腙通过缩合反应转变成1,3,4-二唑化合物, 消除了甲基空间取向的差异, 其信号变为单峰.     

Fluorescence properties in a single driven four-level atomic system

The spontaneous emission decay dynamics of a tripod configuration four-level atom driven by a single laser field is studied.Under different initial conditions,we discuss the effects of quantum interference and detuning of external driving field on atomic spontaneous emission properties.For the larger detuning,the interesting phenomena of the spectral line narrowing are found which stem from the contribution of external driving field.     

HPLC-MS结合多元统计分析区分人参产地及筛选皂苷类标志物

利用高效液相色谱-质谱联用(HPLC-MS)技术结合多元统计分析方法, 区分中国人参主产区5个不同产地的45个人参样本, 筛选出差异性皂苷类标志物. 根据人参总皂苷在反相C₁₈色谱柱中的洗脱顺序, 结合串联质谱分析和标准品比对, 在提取的人参总皂苷中鉴定出15种原人参三醇型、 24种原人参二醇型和2种齐墩果酸型共41种皂苷. 对人参总皂苷的HPLC-MS全扫描数据进行了多元统计分析. 正交偏最小二乘-判别分析(OPLS-DA)结果表明, 所建立的分析模型具有良好的数据描述能力和预测能力. 所有人参样本能够根据产地被区分, 并筛选得到同时区分5个产地的差异性皂苷类组分18种; 能够区分任意2个产地人参样本的差异性组分主要为在人参中含量较高的人参皂苷Rb1, Rg1, Re, Rc, Rd, Ro和m-Rb1等. 分层聚类分析(HCA)结果显示, 黑龙江和吉林两省的样本能够独自聚类, 但是绥化市的样本更接近于吉林省. 初步推断原因为绥化市地理位置较接近吉林省, 两地人参生长环境相似并可能存在种质资源交换.     

Multi-Party Quantum Key Agreement Protocol with Bell States and Single Particles

International Journal of Theoretical Physics - Liu et al. [Quantum Inf. Process. 12, 1797–1805 (2013)] proposed a multi-party quantum key agreement (QKA) protocol based on single particles....     

Multiparty Quantum Key Agreement with Four-Qubit Symmetric W State

Based on four-qubit symmetric W state, the delayed measurement, decoy photos method, block transmission technique and the dense coding method, a multi-party quantum key agreement protocol is proposed. By utilizing the delayed measurement and decoy photos method, the fairness and security of the protocol are ensured. That is, the final generation key can be got fairly by m participants and the outside eavesdropper (includes Trojan-horse attacks, Measure-resend attack, Intercept-resend attack and Entangle-measure attack) and the dishonest participants attacks can be resisted in this protocol. By utilizing block transmission technique and the dense coding method, the efficiency of the protocol is improved. The efficiency analysis shows that the proposed protocol is more efficient than other multi-party QKA protocols.     

应用经验模态分解和独立成分分析解译岩矿光谱

岩矿光谱由多种矿物光谱混合而成,解译岩矿光谱能够得到岩矿的组分信息,且该方法具有快速、方便、不损坏样品的特点。经验模态分解(empirical mode decomposition, EMD)不能直接分离出混合信号中的源信号,独立成分分析(independent component analysis, ICA)要求混合信号数目不小于其所包括的源信号数目。将EMD和ICA两种方法相融合,首先用EMD分解混合信号得到本征模态函数(intrinsic mode function, IMF),再选择一定数目的IMF与混合信号一起组成ICA的输入数据矩阵,经过ICA运算可以获取单一混合信号中的源信号信息,克服了EMD和ICA两种方法各自的缺陷。研究表明,综合应用EMD和ICA方法可以获取单一混合信号中的源信号信息,混合信号中源信号含量越大,得到的源信号近似值越理想。参与ICA分离的IMF数目决定了分离得到的源信号近似值的数目,并且选择的IMF与混合信号相关系数越大,得到的源信号近似值越理想。运用该方法定量分析岩矿光谱,可以获取组成岩矿的矿物信息,比较适用于野外作业岩矿的快速分析鉴定及成分初步分析。     

Quantum Secure Communication Using a Class of Three-Particle W State

A theoretical scheme of quantum secure communication using a class of three-particle W states is proposed. In the scheme, two communicators may communicate after they test the security of the quantum channel. The receiver can obtain the secret message determinately if the quantum channel is safe. The present scheme can be realized without using teleportation.     

Synthesis of [100] Wurtzite InN Nanowires and [011] Zinc-Blende InN Nanorods

One-dimensional wurtzite InN nanowires and zincblende InN nanorods are prepared by chemical vapour deposition （CVD） method on natural cleavage plane （110） of GaAs. The growth direction of InN nanowires is [100], with wurtzite structure. The stable crystal structure of InN is wurtzite （w-InN）, zincblende structure （z-InN） is only reported for 2D InN crystals before. However, in this work, the zincblende InN nanorods [011] are synthesized and characterized. The SEM and TEM images show that every nanorod shapes a conical tip, which can be explained by the anisotropy of growth process and the theory of Ehrlich Schwoebel barrier.     

Structural and Optical Properties of Nonpolar m-Plane GaN and GaN-Based LEDs on γ-LiAlO_2

We report the structural and optical properties of nonpolar m-plane GaN and GaN-based LEDs grown by MOCVD on a 7-LiAlO2 （100） substrate. The TMGa, TMIn and NH3 are used as sources of Ga, In and N, respectively. The structural and surface properties of the epilayers are characterized by x-ray diffraction, polarized Raman scattering and atomic force microscopy （AFM）. The films have a very smooth surface with rms roughness as low as 2nm for an area of 10×10μm^2 by AFM scan area. The XRD spectra show that the materials grown on 7-LiAl02 （100） have （1 - 100） m-plane orientation. The EL spectra of the m-plane InGaN/GaN multiple quantum wells LEDs are shown. This demonstrates that our nonpolar LED structure grown on the 7-LiAlO2 substrate is indeed free of internal electric field. The current voltage characteristics of these LEDs show the rectifying behaviour with a turn on voltage of 1-3 V.     

一维Ni0.5Zn0.5Fe2O4/SiO2复合纳米结构的制备及其磁性能

采用溶胶-凝胶法结合静电纺丝技术制备了Ni_0.5Zn_0.5Fe₂O₄/SiO₂复合纳米纤维.利用热重-差热分析、X射线衍射、场发射扫描电镜、高分辨透射电镜和振动样品磁强计研究了前驱体纤维的热分解及相转化过程以及焙烧温度和SiO₂含量对目标纳米纤维的相组成、微观结构、形貌及磁性能的影响.结果表明,在450 ℃焙烧时,立方尖晶石结构已基本形成.随着焙烧温度由450 ℃升高到100