色谱分析中的串联技术

样品中物质信息的获取离不开分离和检测,对于复杂样品的分析,简单的一维色谱方法常常难以完成所有组分的分离和鉴定。为此,多种色谱串联技术引起了人们的广泛关注。色谱串联技术包括柱串联技术、检测器串联技术、多维色谱等。该文详细介绍了以上3种串联技术（不包括色谱-质谱联用技术）自2010年以来的最新研究进展,以及这些技术在获取样品中更加全面和精准的信息方面的典型应用。最后对色谱串联分析技术的发展进行了总结和展望。     

基于光谱和成像技术的果蔬质量检测研究进展

为保证食品安全和消费者健康,无损检测技术广泛应用于果蔬质量检测中。光谱和图像技术可分别获取果蔬的内部和外部信息,成为质量检测的有效工具。为跟踪国内外研究进展并分析研究现况,从果蔬外部品质(尺寸、形状、表面缺陷、颜色、纹理等)、内部品质(内部缺陷、可溶性固形物、可滴定酸、水分、类胡萝卜素等单一品质及综合品质)、成熟度、货架期/贮藏期、产品溯源、生长监测、安全(农药残留、病虫和细菌侵染、转基因产品等)检测及光学系统设计等方面综述了光谱和成像技术的应用,分析了存在的图谱库不完善、解混处理算法复杂、高精度和便携式的光学系统开发力度不够、校正模型的影响因素复杂等问题。然后,归纳了发展趋势,指出了各组分可视化分析及交互作用机理解析、光与果蔬组织的交互作用机理分析和光学特性参数反演等光学特性分析、科学合理的综合评价体系的建立、新算法的应用和多种算法的联合使用、不同算法的可靠性和稳定性的提高、稳定和普适模型的建立、低成本和便携式等光学分析仪器的商品化开发和商业化应用等成为进一步探索的方向,为基于光谱和成像技术的果蔬质量检测发展提供了参考。     

连续推扫计算光谱成像技术

计算光谱成像技术具有高通量、快照成像等优点,但快照成像采样数据量不足,导致利用压缩感知方法重构图谱精度很低。通过对计算光谱成像技术各个环节进行系统研究,提出一种新型的连续推扫计算光谱成像技术,利用正交循环编码孔径代替传统的随机编码孔径,通过逐行扫描方式及正交变换可完整重构图谱数据。仿真和实际成像结果表明,连续推扫计算光谱成像技术可消除图谱混叠影响,理论上可完全重构图谱信息,重构图谱精度明显优于传统的计算光谱成像技术。相比国际上提出的多次曝光计算光谱成像技术,连续推扫计算光谱成像技术不需要改变编码孔径与探测器间的相对位置,也不需要凝视成像,系统中没有活动元件,稳定性高,适用于常规航空航天遥感推扫成像。     

宽光谱干涉显微术快速提取内指纹

指纹识别是一种广泛应用的生物特征识别技术,但现有指纹身份识别装置由于容易被指纹膜欺骗而存在安全问题,手指表面弄脏、太湿或者磨损也会导致识别失效,存在鲁棒性差的问题。手指内部220～550 μm的皮肤层,具有表面(外部)指纹相同的拓扑特征。这些内部层,充当“主模板”导致外部指纹按照它的形状生长,另外,手指内部的汗腺和微血管结构也和指纹有跟随形状。这些皮下指纹,和对应层面的汗腺等组织结构,具有终生不变性,我们称之为内指纹。内指纹难以仿制,可以用于准确而高度鲁棒的生物身份识别。但是目前报道的用扫频层析术获得内指纹图像,由于对二维正面图像提取需要扫描,并最终从三维指纹结构中重构正面图像,数据量大,提取速度太慢,限制了其实用性。提出一种基于宽光谱干涉显微术的手指皮肤下内部指纹成像系统,以宽光谱弱相干白光激光实现3.5 μm轴向分辨率,采用低数值孔径的光路提高了穿透深度,利用光源空间非相干性和阵列探测器无需扫描一次性获得6.14 mm×6.14 mm的内指纹图像,实现了0.4 s每帧的快速读取,并以三维分层图像展示了手指内部指纹,及其汗腺结构等特征,该工作确认了宽广谱干涉显微术快速提取内指纹用于生物识别的可行性,为高安全度生物识别提供了新方法。     

基于地理探测器的浙江省空气质量风险因子分析

随着经济改革和城市化建设进程的加快,我国的空气质量正面临着空前的压力.识别城市化过程中影响空气质量的风险因子,探究不同城市化与空气质量耦合协调阶段的风险因子及其决定力的差异,有助于政府在发展城市经济的同时合理预防、控制和治理空气污染.根据2015年浙江省各市城市化与空气质量耦合协调度计算结果,将全省划分为协调发展、转型过渡和不协调发展3种区域,运用地理探测器揭示全省不同耦合协调分区的空气质量风险因子.研究表明：（1）不同耦合协调分区的主要风险因子不完全相同;（2）城市化因子通常与年均AQI值正相关,与自然、气象因子负相关;（3）风险因子的两两共同作用加强了对空气质量空间分布的解释力.     

一维位置敏感探测器位置准确度和线性度的改进

在常规的条状一维位置敏感探测器（PSD）中,光敏区和位置电阻区是结合在一起的,器件的欧姆接触电极难以做得比较理想,因此器件的位置准确度和线性度也受到了不利的影响。而在梳状一维位置敏感探测器中,光敏区和位置电阻区被分成了梳齿区和梳脊区两部分,并且位置电阻区被设计成很窄的长条,即使掺杂浓度比较高,位置电阻也能做得相当大。这样条状一维位置敏感探测器接触电极上的缺陷就可消除。用两种不同的一维位置敏感探测器所测量的位置特性曲线证实了理论分析的正确性。测量结果还表明,梳状一维位置敏感探测器的位置准确度和线性度比条状一维位置敏感探测器有了显著的提高,梳状一维位置敏感探测器的平均位置误差从条状一维位置敏感探测器的55μm减小到了26μm,梳状一维位置敏感探测器的均方根非线性度从条状一维位置敏感探测器的0．94％减小到了0．09％。     

Gamma-ray tracking: Utilizing new concepts in the detection of gamma-radiation

Gamma-ray tracking in a closed array of highly segmented HPGe detectors is a new concept for the detection of γ-radiation. Each of the interacting γ-rays is identified and separated by measuring the energies and positions of individual interactions and by applying tracking algorithms to reconstruct the scattering sequences, even if many γ-rays hit the array at the same time. The three-dimensional position and the energy of interactions are determined by using two-dimensionally segmented Ge detectors along with pulse-shape analysis of the signals. Such a detector will have new and much improved capabilities compared to current γ-ray spectrometer. One implementation of this concept, called GRETA (Gamma-Ray Energy Tracking Array), is currently being under development at LBNL. Received: 21 March 2002 / Accepted: 16 May 2002 / Published online: 31 October 2002 RID="a" ID="a"e-mail: kvetter@lbl.gov     

Magnetic resonance imaging of isolated single liposome by magnetic resonance force microscopy

Magnetic resonance imaging (MRI) is very useful spectroscopy to visualize a three-dimensional (3D) real structure inside the sample without physical destruction. The spatial resolution of the readily available MRI spectrometer is, however, limited by a few ten to hundreds of microns due to a technological boundary of generating larger magnetic field gradient and to the insensitivity inherent to the inductive signal detection. Magnetic resonance force microscopy (MRFM) is new alternative MRI spectroscopy which is anticipated to significantly surpass the conventional MRI in both resolution and sensitivity. We report two imaging experiments on our MRFM spectrometer operated at room temperature and in vacuum approximately 10(-3)Pa. One is for approximately 20 microm liposome membrane labeled entirely by a nitroxide imaging agent and the other for approximately 15 microm DPPH particles, both are nearly the same size as that of human cell. The reconstructed images at spatial resolution approximately 1 microm were in satisfactory agreement with the scanning electron microscope images. The potential capability of visualizing intrinsic radicals in the cell is suggested to investigate redox process from a microscopic point of view.     

Optical metrology for massive detectors of gravitational waves

The high level reached in the stability of laser sources and in the quality of optical components makes interferometric metrology appealing to those involved in the search for detection of gravitational waves (GWs). In this paper we present a readout for massive detectors of GWs, based on laser interferometry with high finesse Fabry–Pérot cavities, and describe the frequency stability of the laser source. The achievable sensitivity at the quantum limit level inherent to this technique requires a careful design, in order to reduce other sources of extra noise. In particular, we focus on the local effects of thermal and radiation pressure fluctuations and present an optical configuration that can reduce these effects below the quantum limit level.     

Diverse imaging of photonic crystal by the effects of channeling and partial band gap

Diverse imaging of point source by a two-dimensional photonic crystal slab with square lattice is studied by the finite-difference time-domain method. Given proper frequencies, there seems to be some special directions like channels guiding the light propagation inside the photonic crystal, along which some images will be created. It is suggest that except negative refraction there should be other mechanisms making point image by two dimensional photonic crystal slab.