Cs4Sn5S12的溶剂热合成与表征

利用溶剂热法合成了硫代锡酸铯Cs4Sn5S12,单晶X-射线衍射结果表明Cs4Sn5S12属正交晶系,Pbca空间群,a=1.4232(4)nm,b=1.3161(4)nm,c=1.6372(5)nm,α=90°,Z=4。化合物Cs4Sn5S12中含有由八面体Sn S6和三角双锥Sn S5连接形成的层状阴离子[Sn5S12]4-∞。[Sn5S12]4-∞结构中有两种类型硫原子:连接六配位锡原子和五配位锡原子的硫原子以及只与两个五配位锡原子相连的硫原子。紫外-可见漫反射光谱表明Cs4Sn5S12为半导体,禁带宽度为2.3 e V。     

Femtosecond laser time-of-flight mass spectrometry of labile molecular analytes: laser-desorbed nitro-aromatic molecules.

Femtosecond laser time-of-flight mass spectra of solid samples of trinitrobenzene (TNB), trinitrotoluene (TNT) and trinitrophenol (TNP) have been recorded. Desorption of the solid samples was enacted by the fourth harmonic output (266 nm) of a 5 ns Nd:YAG laser. Subsequent femtosecond post-ionisation of the plume of neutral molecules was achieved using 800 nm laser pulses of 80 fs duration. Mass spectra have been recorded for desorption laser intensities from 2-6 x 10(9) W cm(-2) with ionisation laser intensities between 2 x 10(14) and 6 x 10(15) W cm(-2). Femtosecond laser ionisation has been shown to be capable of generating precursor and characteristic high-mass fragment ions for labile nitro-aromatic molecules commonly used in high-explosive materials. This feature is critical in the future development of femtosecond laser-based analytical instruments that can be used for complex molecular identification and quantitative analysis of environmentally important labile molecules. Furthermore, a comparison of femtosecond post-ionisation mass spectra with standard 70 eV electron impact data has revealed similarities in the spectra and hence the fragmentation processes.     

聚呲咯的研究

本文研究了不同电化学氧化聚合条件下所得聚吡咯的红外光谱,X射线光电子能谱、元素分析、X射线衍射图及扫描电子显微镜图等。对聚吡咯的电导性、电导率的依赖性、化学结构及结晶性等进行了讨论。     

高效液相色谱二氮杂冠醚键合相的合成及性能研究

本文报道在硅胶表面进行固－液相反应，合成硅胶键合二氮杂冠醚高效液相色谱固定相。采用有机元素分析、热分析、红外光谱、金属离子的络合容量测定等对键合材料进行鉴定和表征，并对其色谱性能进行了研究。     

Interaction mechanism of some alkyl iodides with femtosecond laser pulses

The interaction of 1-iodopropane, 2-iodopropane, 1-iodobutane, 2-iodobutane, and 1-iodopentane with (5 x 10(13-)5 x 10(15) W/cm2) femtosecond laser fields is studied by means of a time-of-flight mass spectrometer. It is found that multiphoton ionization (MPI) and field ionization (FI) processes are involved in the molecular ionization. The contribution of these processes can be distinguished using the peak profile of the ions in the mass spectra. Thus, from the mass spectra of 2-iodoropane and 2-iodobutane, it is concluded that MPI processes are taking place even for Keldysh parameter values gamma approximately 0.3. The field ionization process depends on the characteristics of the molecular binding potential well and leads to an asymmetric charge distribution of the transient multiply charged parent ions. In the case of 1-iodobutane, the MPI processes lead to a stable doubly charged parent ion production with a laser intensity threshold higher than that found for I2+ ions. In addition, the isomers studied exhibit distinct differences in their mass spectra and their origin is discussed in detail.     

5-甲基-[(2E,6E)-3,7,11-三甲基-9-氧代十二碳二烯]苯醌和氢醌的首次全合成

以2-甲基对苯二酚和香叶基溴为起始原料, 经过酚羟基保护, 溴代, Li₂CuCl₄催化的芳基溴与Grignard试剂的偶联以及Julia偶联等一系列反应, 完成了裸鳃亚动物的代谢产物, 5-甲基-[(2E,6E)-3,7,11-三甲基-9-氧代十二碳二烯]苯醌(1)和氢醌(2)的首次全合成, 将1用NaBH₄还原, 得到(±)-3, (±)-3也是此类天然产物之一.     

(-)-（3S, 6R）-3, 6-羟基-10-甲基十一酸及其三聚体的全合成

以廉价易得的异戊基溴为起始原料,以烯丙基二异松莰烷基硼烷参与的不对称烯丙基化反应和Yamaguchi酯化反应为关键步骤,实现了对(-)-(3S,6R)-3,6-二羟基-10-甲基十一酸(总收率27.5％)及其三聚体(总收率24.5％)的不对称全合成。     

An analytical approach to reconstruction of axisymmetric defects in pipelines using T(0, 1) guided waves

Torsional guided waves have been widely utilized to inspect the surface corrosion in pipelines due to their simple displacement behaviors and the ability of longrange transmission. Especially, the torsional mode T (0, 1), which is the first order of torsional guided waves, plays the irreplaceable position and role, mainly because of its non-dispersion characteristic property. However, one of the most pressing challenges faced in modern quality inspection is to detect the surface defects in pipelines with a high level of accuracy. Taking into account this situation, a quantitative reconstruction method using the torsional guided wave T (0, 1) is proposed in this paper. The methodology for defect reconstruction consists of three steps. First, the reflection coefficients of the guided wave T (0, 1) scattered by different sizes of axisymmetric defects are calculated using the developed hybrid finite element method (HFEM). Then, applying the boundary integral equation (BIE) and Born approximation, the Fourier transform of the surface defect profile can be analytically derived as the correlative product of reflection coefficients of the torsional guided wave T (0, 1) and the fundamental solution of the intact pipeline in the frequency domain. Finally, reconstruction of defects is precisely performed by the inverse Fourier transform of the product in the frequency domain. Numerical experiments show that the proposed approach is suitable for the detection of surface defects with arbitrary shapes. Meanwhile, the effects of the depth and width of surface defects on the accuracy of defect reconstruction are investigated. It is noted that the reconstructive error is less than 10%, providing that the defect depth is no more than one half of the pipe thickness.     

基于球形压电陶瓷的耐压水听器

利用球形压电陶瓷自身所具有的耐压能力,采用径向极化空气背衬压电球壳换能器作为声学接收敏感元件,设计并制作了一种球形耐压水听器。首先对其低频开路接收灵敏度和谐振频率等声学特性进行了分析和有限元仿真,然后对其强度和稳定性等耐压性能进行了分析和有限元仿真,最后对其声学性能和耐压能力进行了测试。测试表明,该球形耐压水听器的直径为36 mm,工作频段为50 Hz～10 kHz,低频接收灵敏度为-198.4 dB (0 dB=1 V/μPa),等效自噪声谱级为46.5 dB@1 kHz,其耐压深度可达3000 m。该耐压水听器为大深度水听器设计提供了参考,在深水声学领域具有重要的应用价值。