19F-NMR进展

19F-NMR技术由于其化学位移范围大、不易出现峰重叠及灵敏度高等优点,自上个世纪50年代出现以来,在分析光学异构体,生命科学等研究中有其特殊意义.在体内核磁共振技术中,19F-NMR与其他方法相比,在不损伤样品的条件下,就可进行实时定量监测.近30年,引人氟代指示剂进行体内19F-NMR的研究,含氟生物活性物质以及含氟材料的研究受到很大的重视,19F-NMR技术及其应用发展起来.从近10年的情况来看,含氟生物活性物质的研究以及在医药、农药和具有优异性能的含氟材料的研究应用受到很大的重视,这是近期19F-NMR研究发展的一个主要特点.     

Waiting times of entangled electrons in normal–superconducting junctions

We consider a normal–superconducting junction in order to investigate the effect of new physical ingredients on waiting times. First, we study the interplay between Andreev and specular scattering at the interface on the distribution of waiting times of electrons or holes separately. In that case the distribution is not altered dramatically compared to the case of a single quantum channel with a quantum point contact since the interface acts as an Andreev mirror for holes. We then consider a fully entangled state originating from splitting of Cooper pairs at the interface and demonstrate a significant enhancement of the probability to detect two consecutive electrons in a short time interval. Finally, we discuss the electronic waiting time distribution in the more realistic situation of partial entanglement.     

Coherent electron transport in a helical nanotube

The quantum dynamics of carriers bound to helical tube surfaces is investigated in a thin-layer quantization scheme. By numerically solving the open-boundary Schrödinger equation in curvilinear coordinates, geometric effect on the coherent transmission spectra is analysed in the case of single propagating mode as well as multimode. It is shown that, the coiling endows the helical nanotube with different transport properties from a bent cylindrical surface. Fano resonance appears as a purely geometric effect in the conductance, the corresponding energy of quasibound state is obviously influenced by the torsion and length of the nanotube. We also find new plateaus in the conductance. The transport of double-degenerate mode in this geometry is reminiscent of the Zeeman coupling between the magnetic field and spin angular momentum in quasi-one-dimensional structure.     

氢化物发生—原子荧光法测定不同产地绞股蓝及其根际土壤中As,Hg,Se

通过优化了的氢化物发生—原子荧光法测定了7个省产绞股蓝及其根际土壤中As,Hg,Se三种元素的含量,研究结果表明:7个省产绞股蓝中As,Hg,Se的含量存在较大差异,但As和Hg两种重金属元素含量均低于《药用植物及制剂进出口绿色行业标准》中As和Hg的限量标准。Se元素含量同根际土壤中Se元素含量显示极显著相关性,故湖北恩施富硒区产绞股蓝中Se含量明显高于其他6省产绞股蓝。研究结果可以初步判定,绞股蓝中Se元素主要来源于土壤,而As和Hg元素的积累则不同于Se元素,还可能受到大气气溶胶的干、湿沉降等因素的影响。     

一种对于接收者更优的三能级两粒子态控制隐形传态方案

建立了一个基于非最大纠缠量子信道的三能级两粒子的概率隐形传态的方案.在本方案中概率隐形传态的实现应用了新的正交完备测量基来代替传统的Bell基,我们用三能级量子纠缠态作为通道.这是和前人的隐传方案所不同的.我们所提出的方案对于接受者来说更加方便、简洁,使用者能够通过较少的操作来实现通信.     

流动注射化学发光法测定盐酸曲普利啶

在碱性溶液中,N-氯代丁二酰亚胺可以氧化二氯荧光素产生化学发光。盐酸曲普利啶的存在可以显著地增强这一反应的化学发光信号。基于此,结合流动注射技术,优化了实验条件,建立了测定盐酸曲普利啶的流动注射化学发光新方法。该方法测定盐酸曲普利啶的线性范围1.0×10^-9—1.0×10^-7g/mL,检出限为5.0×10^-10g/mL。对浓度为7.0×10^-9g/mL盐酸曲普利啶溶液进行11次平行测定的相对标准偏差为4.1%。该方法已用于药物制剂中盐酸曲普利啶的含量测定,结果令人满意。     

化学成键的元素中的退化费米气体中的束缚电子对

Cooper考虑一对电子在一个安稳的费米球面上相互作用着,指出这种相互作用是由声子和屏蔽库仑场导致的,在电子间存在一种净的吸引作用,结果这对电子能够形成一个束缚态.我们给出的是对于元素之中有化学键的形成,甚至电了发生了转移,电负性高的元素得到了电子,电负性低的元素失去了电子时退化费米气体中的束缚电子对的描述.     

Simultaneous chromatic dispersion monitoring,extinction ratio enhancement and wavelength conversion using four-wave mixing

This paper presents a multi-functional all-optical device performs simultaneous chromatic dispersion (CD) monitoring, extinction ratio (ER) improvement and tunable wavelength conversion using four-wave mixing (FWM) in a single piece of highly nonlinear optical fiber (HNLF). The multi-functional ability arises from the nonlinear power transfer function (PTF) between the input signal and the output idler wave, which not only maps the CD information of the signal onto the average power of idler wave, but also transfers the data information to the idler wave with ER enhancement, making the device compact and cost effective. Furthermore within the wavelength tuning range the monitoring sensitivity and output ER can be much higher compared to all optical monitors and regenerators proposed before. Numerical simulations are then used to demonstrate the efficiency of this method.     

Preparation of Nd-doped BiFeO3 films and their electrical properties

The Nd-doped BiFeO₃ thin films were prepared on SnO₂(FTO) substrates spin-coated by the sol–gel method using Nd(NO₃)₃·6H₂O, Fe(NO₃)₃·9H₂O and Bi(NO₃)₃·5H₂O as raw materials. The microstructure and electric properties of the BiFeO₃ thin films were characterized and tested. The results indicate that the diffraction peak of the Nd-doped BiFeO₃ films is shifted towards right as the doping amounts are increased. The structure is transformed from the rhombohedral to pseudotetragonal phase. The crystal grain is changed from an elliptical to irregular polyhedron. Structure transition occurring in the Bi_0.85Nd_0.15FeO₃ films gives rise to the largest Pr of 64 μC/cm². The leakage conductance of the Nd doped thin films is reduced. The dielectric constant and dielectric loss of Bi_0.85Nd_0.15FeO₃ thin film at 10 kHz are 190 and 0.017 respectively.     

凤党脂溶性成分的GC-MS分析

采用索氏提取法提取凤党脂溶性成分,甲酯化后,气相色谱-质谱联用（GC-MS）进行分析,计算机检索结合人工解析进行成分分析和鉴定,共分离得到48个峰,鉴定了其中39种成分。在凤党脂溶性成分中主要含有亚油酸（29.73%）、棕榈酸（12.94%）、油酸（3.14%）、亚麻酸（1.83%）、硬脂酸（1.64%）和角鲨烯（12.00%）等。