单颗粒气溶胶实时在线监测飞行时间质谱仪的研制

介绍国内第一台采用空气动力学透镜进样系统的质谱仪。这种系统有效地提高进样效率和检测效率。本仪器优化双光束测径装置和激光解析电离装置的空间结构,缩短气溶胶漂移空间从而提高小颗粒的检测极限。     

Mass spectrometry of atmospheric aerosols--recent developments and applications. Part I: Off-line mass spectrometry techniques

Many of the significant advances in our understanding of atmospheric particles can be attributed to the application of mass spectrometry. Mass spectrometry provides high sensitivity with a fast response time to probe chemically complex particles. This review focuses on recent developments and applications in the field of mass spectrometry of atmospheric aerosols. In Part I of this two-part review, we concentrate on off-line mass spectrometry techniques, which require sample collection on filters but can provide detailed molecular speciation. In particular, off-line mass spectrometry techniques utilizing tandem mass spectrometry experiments and high resolution mass analyzers provide improved insight into secondary organic aerosol formation and heterogeneous reaction pathways through detailed structural elucidation at the molecular level.     

Mass spectrometry of atmospheric aerosols--recent developments and applications. Part II: On-line mass spectrometry techniques

Many of the significant advances in our understanding of atmospheric particles can be attributed to the application of mass spectrometry. Mass spectrometry provides high sensitivity with fast response time to probe chemically complex particles. This review focuses on recent developments and applications in the field of mass spectrometry of atmospheric aerosols. In Part II of this two-part review, we concentrate on real-time mass spectrometry techniques, which provide high time resolution for insight into brief events and diurnal changes while eliminating the potential artifacts acquired during long-term filter sampling. In particular, real-time mass spectrometry has been shown recently to provide the ability to probe the chemical composition of ambient individual particles <30 nm in diameter to further our understanding of how particles are formed through nucleation in the atmosphere. Further, transportable real-time mass spectrometry techniques are now used frequently on ground-, ship-, and aircraft-based studies around the globe to further our understanding of the spatial distribution of atmospheric aerosols. In addition, coupling aerosol mass spectrometry techniques with other measurements in series has allowed the in situ determination of chemically resolved particle effective density, refractive index, volatility, and cloud activation properties.     

Aerosol laser time-of-flight mass spectrometer for the on-line measurement of secondary organic aerosol in smog chamber

An aerosol laser time of flight mass spectrometer (ALTOFMS) that can be used for real-time measurement of the size and composition of individual aerosol particles has been designed and utilized to provide on-line measurement of secondary organic aerosol (SOA) particles resulted from Cl-initiated oxidation of toluene in smog chamber. Both the size and chemical compositions of individual aerosol particles were obtained in real-time. According to a large number of single aerosol diameters and mass spectra, the size distribution and chemical composition of aerosol were determined statistically. Experimental results indicate that aerosol particles produced from Cl-initiated oxidation of toluene were predominantly in the form of PM 2.5 particles, and nine positive laser desorption/ionization mass spectra peaks: m/z 18, 29, 30, 44, 46, 52, 65, 77, and 94 may come from the fragment ions of the products of the SOA: aromatic aldehydes, aromatic acids, phenolic compounds, and nitrogenated organic compounds. These results were in good agreement with those ones from previous Cl-initiated oxidation of toluene. These were demonstrated that ALTOFMS is a useful tool to reveal the formation and transformation processes of SOA particles in smog chamber.     

微脉冲激光雷达反演气溶胶的水平分布

城市近地面气溶胶的分布随时空快速变化,常用的地基定点监测只能获取区域内有限位置的气溶胶质量浓度,大致反映区域内气溶胶的分布情况。为确定气溶胶和污染物在城市近地面水平路径上的分布情况,利用微脉冲激光雷达(MPL)、粒子计数器、能见度仪和颗粒物质量浓度监测仪获得的气溶胶数据,根据Mie散射理论建立了气溶胶消光系数、粒子谱分布和质量浓度等参数的数学模型,反演得到了水平路径上的气溶胶质量浓度分布。该方法可以以测量点为中心进行0~6km的360°的水平扫描,具有监测范围大、分辨率高的优点。最后开展了气溶胶水平分布的实际测量,获得了距离6km长的水平路径上近地面气溶胶质量浓度的实时分布。这为研究城市气溶胶的污染来源和动态变化提供了有效的数据支持。     

Chemical ionization tandem mass spectrometer for the in situ measurement of methyl hydrogen peroxide

A new approach for measuring gas-phase methyl hydrogen peroxide [(MHP) CH(3)OOH] utilizing chemical ionization mass spectrometry is presented. Tandem mass spectrometry is used to avoid mass interferences that hindered previous attempts to measure atmospheric CH(3)OOH with CF(3)O(-) clustering chemistry. CH(3)OOH has been successfully measured in situ using this technique during both airborne and ground-based campaigns. The accuracy and precision for the MHP measurement are a function of water vapor mixing ratio. Typical precision at 500 pptv MHP and 100 ppmv H(2)O is ±80 pptv (2 sigma) for a 1 s integration period. The accuracy at 100 ppmv H(2)O is estimated to be better than ±40%. Chemical ionization tandem mass spectrometry shows considerable promise for the determination of in situ atmospheric trace gas mixing ratios where isobaric compounds or mass interferences impede accurate measurements.     

Measurement of trace atmospheric species by chemical ionization mass spectrometry: speciation of reactive nitrogen and future directions

Chemical ionization mass spectrometry (CIMS) has proven to be a powerful method for sensitive, fast time response (t approximately 1 sec) measurements of various atmospheric compounds with limits of detection (LOD) of the order of tens of pptv and lower. The rapid time response of CIMS is particularly well suited for airborne measurements and its application has largely grown out of airborne measurements in the stratosphere and upper troposphere. This work reviews some of the advances in CIMS technology that have occurred in the past decade. In particular, CIMS methods for selective measurement of reactive nitrogen species (e.g., HNO3, HO2NO2, PAN, and NH3) in the lower atmosphere (altitudes approximately 0-8 km) are described. In addition, recent developments in CIMS technology for the selective measurement of gas-phase hydroperoxides and aerosol chemical composition are briefly described.     

Analytical affective design with ambient intelligence for mass customization and personalization

The fulfillment of individual customer affective needs may award the producer extra premium in gaining a competitive edge. This entails a number of technical challenges to be addressed, such as the elicitation, evaluation, and fulfillment of affective needs, as well as the evaluation of affordability of producers to launch the planned products. Mass customization and personalization have been recognized as an effective means to enhance front-end customer satisfaction while maintaining back-end production efficiency. This paper proposes an affective design framework to facilitate decision-making in designing customized product ecosystems. In particular, ambient intelligence techniques are applied to elicit affective customer needs. An analytical model is proposed to support affective design analysis. Utility measure and conjoint analysis are employed to quantify affective satisfaction, while the producer affordability is evaluated using an affordability index. Association rule mining techniques are applied to model the mapping of affective needs to design elements. Configuration design of product ecosystems is optimized with a heuristic genetic algorithm. A case study of Volvo truck cab design is reported with a focus on the customization of affective features. It is demonstrated that the analytical affective design framework can effectively manage the elicitation, analysis, and fulfillment of affective customer needs. Meanwhile, it can account for the manufacturer’s capabilities, which is vital for ensuring a profit margin in the mass customization and personalization endeavor.     

Modulus characterization of cells with submicron colloidal probes by atomic force microscope

Colloidal probes have been increasingly demanded for the characterization of cellular modulus in atomic force microscope because of their well-defined geometry and large contact area with cell. In this work, submicron colloidal probes are prepared by scanning electron microscope/focused ion beam and compared with sharp tip and micron colloidal probe, in conjunction with loading velocity and indentation depth on the apparent elastic modulus. NIM and cartilage cells are used as specimens. The results show that modulus value measured by sharp tip changes significantly with loading velocity while remains almost stable by colloidal probes. Also, submicron colloidal probe is superior in characterizing the modulus with increasing indentation depth, which could help reveal the mechanical details of cellular membrane and the modulus of the whole cell. To test the submicron colloidal probe further, the modulus distribution map of cell is scanned with submicron colloidal probe of 50 nm radius during small and large indentation depths with high spatial resolution. The outcome of this work will provide the effective submicron colloidal probe according to the effect of loading velocity and indentation depth, characterizing the mechanical properties of the cells.     

四极质谱检测中复合放大器的低噪声高带宽设计

四极质谱峰信号是10-11A到10-6A级的微弱电流,并且快速变化,所以在大动态范围内实现低噪声和高带宽是设计关键。设计一种开环增益(ac)可调整的同相输入复合跨阻抗放大器,分析ac对信号和噪声的作用。在较低放大倍率时,改变ac后同相输入复合放大器会降低自身产生的噪声,实现低噪声;在较高放大倍率时,改变ac后同相输入复合放大器能扩展被极高阻值的反馈电阻和寄生电容降低的信号带宽。实验结果表明：与反相输入复合放大器相比,同相输入复合放大器在106-107V/A放大时能降低5-30%噪声,在108V/A放大时扩展带宽1.8倍并提高10-15%质谱峰强度,提高了质谱峰的信噪比。     

三重四级杆质谱仪的安装应用和维护

质谱技术已经成为一种重要的现代分析鉴定技术,三重四级杆质谱,采用空间串联四级杆分析器,对选择离子分析具有较高灵敏度,应用广泛.建议专人负责质谱的安装,管理,应用及维护.维持稳定的电源,充足的液氮和氮气,及时清洗和维护,以保证质谱仪正常,稳定的工作.     

监控软件对小型流程质谱分析系统的性能优化

小型流程质谱计是一种以四极质谱计为分析器、对工业过程中的气体成分进行监控和分析的仪器。其广泛应用于现代化工、制药、建材、食品等工业,对生产流程、质量进行精确控制,小型流程质谱计分析系统性能的高低直接影响这些产品的生产和质量,其性能指标主要指分析系统的稳定性和精度。本文从监控软件设计的数学建模、分析方法等方面探讨如何提高分析系统的性能。     

A porous carbon film for the collection of atmospheric aerosol for transmission electron microscopy

This paper describes a method of direct sampling of fine urban aerosol using porous carbon films, to increase collection efficiency and retain the structural integrity of the aerosol. A nuclepore membrane filter was coated with carbon and washed with chloroform to leave a clean porous carbon film on a 200-mesh transmission electron microscope copper grid. The grid was attached to a clean nuclepore filter using carbon cement. Sampling was conducted for 1 h at 1.9 L min⁻¹ flow rate. The porous carbon grid with sample was then assayed using transmission electron microscopy, and negatives were suitable for image analysis. The collection of fine airborne particles using this method is appropriate for electron microscopy, with a minimum of interference to the structure of collected particles.     

微流控芯片与电喷雾质谱联用接口的制作与应用

介绍了自制玻璃微流控芯片与电喷雾离子化质谱(ESI-MS)联用接口的制作方法。在芯片边缘直接将外接管路与管道相连，通过芯片上的旁路引入辅助液体，通过电场或压力驱动将样品送入质谱仪，实现稳定电喷雾。以芯片作为预进样平台，利用质谱检测了蛋白混合物、兴奋剂类药物混合物和中药提取物。在接口制作中，使用CB胶和保护性盖片，解决了机械加工步骤(切割、打磨和打孔等)中对微型结构的保护封装问题；在外接管路中的金属双通上施加高压电场地电势，实现了芯片管道中液体的电渗泵驱动。     

利用APS实现大气气溶胶数密度和质量浓度的测量

利用自行研制的空气动力学粒谱仪(APS:aerodynam ic particle sizer)测量北京地区大气气溶胶不同粒径段的粒子数密度与质量浓度。对二者进行相关性分析的基础上,运用多元回归方法,得出利用粒子数密度谱获取颗粒物(PM10)质量浓度谱的经验公式,并对公式进行实验验证。同时分析北京市初春大气气溶胶粒子不同空气动力学直径的质量浓度谱特征,以期对北京市大气污染总量控制方案及对策提供科学依据。     

厦门市大气颗粒物中水溶性离子分布特征及其对酸雨的影响研究

为研究厦门市大气颗粒物的污染特征及其对酸雨的影响,于2012年12月至2013年7月在厦门市各区分别采集大气中TSP、PM10、PM2.5颗粒物样品,利用离子色谱法分析了其中的水溶性离子成分含量。结果表明,厦门市大气颗粒物中水溶性离子成分分布特征为：Na＋和Ca2＋离子主要主要分布在TSP、PM10中,而SO42-离子则主要分布在PM10和PM2.5中。说明Na＋和Ca2＋离子更容易富集在粗颗粒物粒子上,而SO42-离子主要存在于细颗粒物粒子中。厦门市大气颗粒物中对雨水酸度有重要缓冲作用的Ca2＋、Mg2＋离子浓度处于较低水平,说明厦门市大气颗粒物对雨水酸度缓冲作用较低,这是厦门地区酸雨发生率较高的原因之一。     

Application of the focused ion beam technique in aerosol science: detailed investigation of selected, airborne particles

The focused ion beam technique was used to fabricate transmission electron microscope lamellas of selected, micrometre‐sized airborne particles. Particles were sampled from ambient air on Nuclepore polycarbonate filters and analysed with an environmental scanning electron microscope. A large number of particles between 0.6 and 10 µm in diameter (projected optical equivalent diameter) were detected and analysed using computer‐controlled scanning electron microscopy. From the resulting dataset, where the chemistry, morphology and position of each individual particle are stored, two particles were selected for a more detailed investigation. For that purpose, the particle‐loaded filter was transferred from the environmental scanning electron microscope to the focused ion beam, where lamellas of the selected particles were fabricated. The definition of a custom coordinate system enabled the relocation of the particles after the transfer. The lamellas were finally analysed with an analytical transmission electron microscope. Internal structure and elemental distribution maps of the interior of the particles provided additional information about the particles, which helped to assign the particles to their sources. The combination of computer‐controlled scanning electron microscopy, focused ion beam and transmission electron microscopy offers new possibilities for characterizing airborne particles in great detail, eventually enabling a detailed source apportionment of specific particles. The particle of interest can be selected from a large dataset (e.g. based on chemistry and/or morphology) and then investigated in more detail in the transmission electron microscope.     

在线质谱仪在工业发酵过程优化与放大中的应用

本文主要介绍了在线质谱仪的特点以及在工业发酵过程优化与放大中的应用。在线质谱仪测量精度高、漂移小、分析速度快,可实现长期连续监测,在生物过程领域具有巨大的应用潜力。