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21.
飞行时间质量分离器是飞行时间质谱仪的主要组成部分。飞行时间质谱(TOF MS)具有分析质量范围宽、分析速度快、仪器结构简单等优点,但离子初始动能和初始位置容易分散是影响其分辨率的核心因素。本综述根据本课题组多年的研制经验,着重介绍离子束垂直引入方式的反射式有栅网飞行时间质谱的离子光学以及相关电子学控制的核心技术原理。离子光学核心技术涉及到离子加速场和离子反射场的机械加工控制和精密装配控制等,电子学控制核心技术主要包括高压电源和高压脉冲电源的精密制作。 相似文献
22.
时间数字转换器(Time-to-Digital Converter,TDC)是一种将连续时间信号转换为数字信号输出的器件,是飞行时间(TOF)激光雷达中的关键部件.在利用计数器粗采样和多相位内插细采样的传统结构上,设计了一种基于相位内插的双级粗细结合型时间数字转换电路,并增加了双回波接收通路来接收多脉冲回波信号,在此基础上设计了一款17通道多路TDC系统芯片.芯片采用CMOS 0.11 μm工艺设计,版图面积为0.6 mm×3 mm.后仿真结果显示,在1.2 V电源下其功耗小于100 mW,单输入精度平均值为51.7 ps,动态范围为3.4 μm,且线性度良好.该TDC芯片适用于飞行时间脉冲激光雷达的信号计时. 相似文献
23.
利用不平衡三维磁光阱(3D-MOT)技术,制备了低速、高通量的连续型原子束。通过使一束冷却光沿着光传播方向形成"中空光束",在MOT中形成一对具有不平衡光辐射压力的对射光束,压力将MOT中冷却与陷俘的87 Rb原子云团从"中空光束"通道中推出产生连续出射的原子。形成的原子束具有一定的速度和速度分布,可反映原子束的相干性。对所制备原子束的相干性进行了测量和分析,结果表明,所产生的原子束的最可几速度约为12m/s,纵向速度分布约为3m/s,对应的德布罗意波波长约为0.4nm,带宽为0.1nm。通过光电倍增管(PMT)收集的荧光强度推算得原子束通量为108~109 atoms/s。 相似文献
24.
Nadine Jaeckels Stefan Tenzer Susanne Rosfa Hansjoerg Schild Heinz Decker Petra Wigand 《Food chemistry》2013
Lipid transfer proteins (LTP) play a major role in plant defence and are of particular interest due to their known ability to cause allergic reactions. These proteins are expressed in grapes and also remain detectable after vinification, especially in red wine. However, it remains unknown whether the protein undergoes any changes during the vinification process. Here, we present a purification method for LTPs from Dornfelder grapes and wine. By liquid-chromatography–mass spectroscopy (LC–MS/MS) we identified LTPs from two different species (Vitis vinifera and Vitis aestivalis). Additionally, the purified LTPs were characterised using spectrometric methods, confirming their high purity and structural stability during vinification. We conclude that LTPs are resistant to the alcohol content (13.5 vol%), acidic milieu of wine and other ingredients present during the vinification process, indicating that the allergenic potential of grape LTP is not diminished by the vinification process. 相似文献
25.
Investigating the chlorination of acidic pharmaceuticals and by-product formation aided by an experimental design methodology 总被引:1,自引:0,他引:1
José Benito Quintana Rosario Rodil Purificación López-Mahía Soledad Muniategui-Lorenzo 《Water research》2010,44(1):243-255
The degradation of seven acidic drugs and two metabolites during chlorination was investigated by liquid chromatography-mass spectrometry (LC-MS). A triple-quadrupole (QqQ) system was used to follow the time course of the pharmaceuticals and by-products, while a quadrupole time-of-flight (Q-TOF) system was also used for the identification of the by-products. Under strong chlorination conditions (10 mg/L Cl2, 24 h), only four of the target compounds were significantly degraded: salicylic acid, naproxen, diclofenac and indomethacine. The degradation kinetics of these four compounds were investigated at different concentrations of chlorine, bromide and pH by means of a Box-Behnken experimental design. Depending on these factors, measured pseudo-first order half-lives were in the ranges: 23-573 h for salicylic acid, 13-446 min for naproxen, 5-328 min for diclofenac and 0.4-13.4 min for indomethacine. Also, it was observed that chlorine concentration was the overall most significant factor, followed by the bromide concentration (except for indomethacine), resulting in increased degradation kinetics as they are increased. The degradation path of salicylic acid, naproxen and diclofenac consisted of aromatic substitution of one or two hydrogens by chlorine and/or bromide. Moreover, for diclofenac, two other by-products corresponding to a decarboxylation/hydroxylation pathway from the monohalogenated products were also identified. On the other hand, indomethacine degradation did not lead to halogenation products but to oxidation ones. The investigation of these by-products in real samples by LC-MS/MS (QqQ) showed that the halogenated derivates of salicylic acid occurred in all the drinking water and wastewater samples analysed. 相似文献
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28.
针对目前基于飞行时间(TOF)原理的3维相机实现物体完整表面的3维点云重建过程中,多视角散乱点云配准精度低的问题,提出一种优化配准方法。该方法通过构建一个目标功能函数,并结合相邻点云的转换矩阵对该目标函数进行最小化求解,直接获取任意位置的点云到基准点云所处坐标系的绝对转换矩阵,避免了对连续点云之间的配准而引起误差的累加。对不同的物体进行实验,实验结果表明,该方法在保证点云配准速度的同时,提高了多视角点云配准的精度,物体点云模型重建效果较好,有利于实现后期3维曲面网格的重建。 相似文献
29.
吴国松 《中国图象图形学报》2013,18(11)
针对目前基于飞行时间(TOF)原理的三维相机实现物体完整表面的三维点云重建过程中,多视角散乱点云配准精度低的问题,本文提出了一种多视角散乱点云优化配准方法。该方法通过构建一个目标功能函数,并结合相邻点云的变换矩阵对该目标函数进行最小化求解,直接获取任意位置的点云到基准坐标系的绝对变换矩阵,避免了对相邻点云的变换矩阵进行累积而引起误差的累加。实验结果表明,该方法提高了多视角点云配准的精度,同时增强了物体点云模型重建的效果,在三维曲面重建中具有较强的实用性。 相似文献
30.
Ming Chang Qingzhe Jin Yuanfa Liu Ruijie Liu Xingguo Wang 《International Journal of Food Science & Technology》2013,48(12):2474-2479
A photodegradation study of Aflatoxin B1 (AFB1) on peanut surface was performed under UV irradiation at different UV irradiation intensities. With an initial quantity of 10 ng of AFB1, it can be degraded thoroughly within 80 min under the intensity of 800 μw cm?2. The photodegradation pathway of AFB1 on the peanut surface was proposed. Mutagenesis and cytotoxicity were assessed after exposure to different concentrations of AFB1 and the mixtures of photodegradation products on the peanut surface. The results of the Ames and in vitro cytotoxicity assay, providing clues to the assessment of safety issues of UV method applied in AFB1 decontamination, indicate that photodegradation products on the peanut surface has no toxicity, which can be explained by the differences in the chemical nature of the test compounds before and after UV irradiation. 相似文献