便携式气相色谱仪共用开发平台中多功能一体化控制器模块的研制

基于整体便携式气相色谱仪共用开发平台的设计理念,研制出了多功能一体化控制器模块.模块包括控制器、功率驱动组件和信号采集组件,直接嵌入到便携式气相色谱仪中.经试验考核,色谱柱温度波动不高于±0.1℃,60℃/min速率升温波动的RSD低于0.15%,进样口和检测器温度波动不高于±0.1℃,柱压不高于±0.16 KPa.以浓度为1 mg/m3的苯标准样品连续6次自动抽取1 m L样品进样分析,定性和定量重复性偏差RSD分别为0.1%和4.6%(峰高),温湿度试验为0~40℃和95%,振动试验(无运输包装)位移为25.4 mm、加速度为1.5 g,以频率5~200~5 Hz正弦波振动与XYZ轴向振动,试验结果正常.模块应用到3种新型仪器中效果理想,满足现场及野外应用要求,具有通用、坚固、体积小和功耗低等特点.     

A semiclassical study of wave packet dynamics in anharmonic potentials

Classical and semiclassical methods are developed to calculate and invert the wave packet motion measured in pump-probe experiments. With classical propagation of the Wigner distribution of the initial wave packet created by the pump pulse, we predict the approximate probe signal with slightly displaced recurrence peaks, and derive a set of first-order canonical perturbation expressions to relate the temporal features of the signal to the characteristics of the potential surface. A reduced dynamics scheme based on the Gaussian assumption leads to the correct center of mass motion but does not describe the evolution of the shape of the wave packet accurately. To incorporate the quantum interference into classical trajectories, we propose a final-value representation semiclassical method, specifically designed for the purpose of computing pump-probe signals, and demonstrate its efficiency and accuracy with a Morse oscillator and two kinetically coupled Morse oscillators. For the case of one-color pump probe, a simple phase-space quantization scheme is devised to reproduce the temporal profile at the left-turning point without actual wave packet propagation, revealing a quantum mechanical perspective of the nearly classical pump-probe signal.     

A simple and sensitive fluorescent sensing platform for Hg²+ ions assay based on G-quenching

In this work, a novel fluorescence biosensor was demonstrated for detection of Hg(2+) ions with relatively high selectivity and sensitivity. The sensing scheme was based on G-quenching induced by Hg(2+) ions. In the presence of Hg(2+) ions, the single-stranded signal probe which has carboxylfluorescein (FAM) and guanine segment at its 5' and 3' ends, respectively, folded into duplex-like structure via the Hg(2+)-mediated coordination of T-Hg(2+)-T base pairs. It brought guannine segment close to the dye and caused a remarkable decrease of fluorescence signal. The sensor showed a sensitive response to Hg(2+) ions in a concentration range from 0.5 to 10 μM, and a detection limit of 0.5 nM was given. This homogeneous system required only a single-labeled oligonucleotide, operated by concise procedures, and possessed comparable sensitivity as previous approaches. Furthermore, the sensor exhibits a great perspective for future practical applications.     

Suppression of Spiral Waves by Generating Self-exciting Target Wave

A new scheme is proposed to suppress stable and meandering spiral waves in excitable media by generating a self-exciting target wave in a local area. An arbitrary selected grid in the media is sampled, and the sampled signal is fed back into a local area in the media. Numerical simulation results confirm its effectiveness when the scheme is introduced into anisotropic (the diffusion coefficient is perturbed vs. time and/or space) and isotropic media. Results also show the scheme's robustness to spatiotemporal noise.     

Wave packet interferometry and quantum state reconstruction by acousto-optic phase modulation

Studies of wave packet dynamics often involve phase-selective measurements of coherent optical signals generated from sequences of ultrashort laser pulses. In wave packet interferometry (WPI), the separation between the temporal envelopes of the pulses must be precisely monitored or maintained. Here we introduce a new (and easy to implement) experimental scheme for phase-selective measurements that combines acousto-optic phase modulation with ultrashort laser excitation to produce an intensity-modulated fluorescence signal. Synchronous detection, with respect to an appropriately constructed reference, allows the signal to be simultaneously measured at two phases differing by 90 degrees. Our method effectively decouples the relative temporal phase from the pulse envelopes of a collinear train of optical pulse pairs. We thus achieve a robust and high signal-to-noise scheme for WPI applications, such as quantum state reconstruction and electronic spectroscopy. The validity of the method is demonstrated, and state reconstruction is performed, on a model quantum system--atomic Rb vapor. Moreover, we show that our measurements recover the correct separation between the absorptive and dispersive contributions to the system susceptibility.     

Filtration of Amplitude Spectra for Reducing the Background Level in X-Ray Fluorescence Analysis

The formation of a background signal in the X-ray fluorescence equipment based on the Soller and Johansson X-ray optics was considered. It was noted that the loss peak arising in the detector should be taken into account. It was proposed that the filtration of the amplitude spectrum coming from the detector to the recording system be used in the scheme with the Johansson crystal. In this method, the intensity of the analytical background can be reduced by several times at a constant level of the analytical signal.     

Integrated isotachophoretic stacking and gel electrophoresis on a plastic substrate and variations in detection dynamic range

In this study, we demonstrated an integrated ITP-gel electrophoresis (GE) device on a plastic substrate, in which 50 nL of samples could be hydrodynamically or electrokinetically injected and enriched by ITP into narrow bands and then subsequently introduced into a homogeneous GE channel for separation and detection. This microchip design rendered a simple introduction scheme for creating sandwiched stacking buffer system and flexibilities in choosing separation and stacking buffers independently. We used gel sieving buffers which compositions were different from those for stacking buffers to separate DNA and protein molecules based on sizing mechanism. Compared to conventional microchip GE, the sensitivity of microchip ITP-GE was estimated to increase by one to two orders of magnitude based on the dilution factor of the injected sample and the S/N ratio detected from the electropherogram. Moreover, it is interesting to note that ITP stacking leads to a preferential enhancement for analytes with lower concentrations compared to those with higher concentrations. Therefore, a reduction in the detection dynamic range for ITP-GE was gained. We demonstrated that ITP-GE could lead to 2-4-folds of reduction in the signal dynamic range for two PCR products in a mixture. Such advantage is demonstrated to be useful for the detection of two products amplified from a multiplex PCR in which one product is poorly amplified compared to the other.     

Near-infrared tetra-substituted aluminum 2, 3-naphthalocyanine dyes for optical fiber applications

The synthesis and spectral characterization of several tetra-substituted aluminum 2, 3-naphthalocyanine dyes for the determination of metal ions is reported. The synthesis is done by means of a homogeneous phase reaction, replacing the previously used heterogeneous method. The new scheme allows for improved product yields, higher purity, better product reproducibility and can be monitored at different stages using UV-Vis-near-infrared spectroscopy. The incorporation of electron-donating or -withdrawing groups was found to influence the product yield and to cause a shift in the absorbance maximum. The typical shift in the excitation maximum (of up to 27 nm) enables the dye to match the output of semiconductor laser diodes. In addition the tetra-substituted groups were capable of undergoing an ion-exchange process with the metal ions which produced a change in the fluorescence signal of the dye. Similar results were achieved using an optical fiber metal probe. The detection of metal ions using the near-infrared dyes was accomplished via steady-state fluorescence using both a commerically available instrument and a fiber optic system and also via the fluorescence lifetime technique.     

Biosensors using integrated optical devices

Summary A label-free, homogeneous immunoassay can be realised using surface single-mode wave guide structures. The evanescent field of the guided mode penetrates the adjacent vicinity of the wave guide, the biochemical layer. Thus, changes in its thickness and refractive index during an antigen-antibody interaction cause a change in the effective refractive index of the wave guide itself. Such small changes can be transformed into intensity modulations using an interferometric set-up. Investigations are described using an integrated optical Mach-Zehnder interferometer (IO-MZ-chip) and the experimental results are compared with model calculations. The theoretical sensitivity of the IO-MZ-chips used was determined applying Maxwell's equations to the propagation of light in stripe wave guides. For the experimental formation of a protein adlayer a three-step biotinavidin protocol for the immobilisation of biotinylated immunoglobulins was employed.Dedicated to Professor Dr. Wilhelm Fresenius on the occasion of his 80th birthday     

Free energy decomposition analysis of bonding and nonbonding interactions in solution

A free energy decomposition analysis algorithm for bonding and nonbonding interactions in various solvated environments, named energy decomposition analysis-polarizable continuum model (EDA-PCM), is implemented based on the localized molecular orbital-energy decomposition analysis (LMO-EDA) method, which is recently developed for interaction analysis in gas phase [P. F. Su and H. Li, J. Chem. Phys. 130, 074109 (2009)]. For single determinant wave functions, the EDA-PCM method divides the interaction energy into electrostatic, exchange, repulsion, polarization, desolvation, and dispersion terms. In the EDA-PCM scheme, the homogeneous solvated environment can be treated by the integral equation formulation of PCM (IEFPCM) or conductor-like polarizable continuum model (CPCM) method, while the heterogeneous solvated environment is handled by the Het-CPCM method. The EDA-PCM is able to obtain physically meaningful interaction analysis in different dielectric environments along the whole potential energy surfaces. Test calculations by MP2 and DFT functionals with homogeneous and heterogeneous solvation, involving hydrogen bonding, vdW interaction, metal-ligand binding, cation-π, and ionic interaction, show the robustness and adaptability of the EDA-PCM method. The computational results stress the importance of solvation effects to the intermolecular interactions in solvated environments.