Positive- and negative-ion matrix-assisted laser desorption/ionization mass spectrometry of saccharides

Matrix-assisted laser desorption/ionization (MALDI) mass spectrometry (MS) of oligosaccharides and polysaccharides has been investigated in detail, It is demonstrated that cationized species of oligosaccharides, [M+Na](+) and [M+K](+), are dominant products under the MALDI condition, and negative ions of oligosaccharides are not formed to any significant extent in this process, The molecular masses of polysaccharides are similarly determined by positive- and negative-ion MALDI-MS with the help of column chromatography. The distinction between positive- and negative-ion MALDI mass spectra of oligo-and polysaccharides indicates that the MALDI processes for saccharides vary with molecular mass. The matrix plays a more important role in the ionization process for oligosaccharides, while in the desorption process for polysaccharides. (C) 1998 John Wiley & Sons, Ltd.

Matrix-assisted laser desorption/ionization of ginsenosides

Molecular weight of 8 ginsenosides and the component of total saponions in American ginseng have been determined by matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS). The average error of the molecular weight of each ginsenoside was found less than 0.05%. The results demonstrate that MALDI-MS is a very simple and useful method to measure the molecular weight of some high polar, thermal unstable small molecules with high sensitivity and reproducibility.

Behavior of silver cluster on laser desorption/ionization time-of-flight mass spectrometry

A successful analysis of silver was reported utilizing laser desorption/ionization time-of-flight mass spectrometry (LDI/TOF-MS) in this paper, The silver cluster ions Ag-n(+) and AgnO+ (n=2 similar to 5) were formed during laser desorption/ionization. In the presence of I-, K+ and Na+, the peaks corresponding, to the cluster ions [AgnIn-1](+) (n=2 similar to 6) and the adduct ions [AgI](+), [AgI]Na+ and [AgI]K+ were observed in the positive ion spectrum; the peaks corresponding to [AgnIn+1](-) (n=1 similar to 3) were found in the negative ion spectrum, all of which accompanied by sliver isotope distribution, The formation of silver cluster ions was accomplished through two-stage reaction: the first step was the generation of clusters, which was followed by the processes of photoionization and ion/molecule reaction.

3种羧酸类基质的基质辅助激光解吸/电离质谱行为

引言基质辅助激光解吸/电离质谱(MALDI-MS)这种新的“软电离”质谱技术，能够在短短10年间，得到广泛应用与迅速发展，很大程度上要归功于基质的辅助效应。基质在样品的解吸/电离过程中，起着关键作用。对基质本身MALDI-MS的研究，不仅可以、刻认识M

人参皂苷的基质辅助激光解吸质谱研究

利用MALDI-TOFMS测定了八种人参皂苷的分子量,并分析了西洋参总皂苷的组成.同时,进行了灵敏度实验,并探讨了基质及碱金属离子的影响,证明该方法灵敏度高,重复性好,结果准确.是测定极性小分子分子量的有效方法.

Formation and special solubility of endohedral thulium metallofullerenes

Endohedral metallofullerenes Tm@C-2n were synthesized with the carbon-arc discharge method of activating the Tm2O3-containing graphite anode in situ and back-burning technique, Toluene soxhlet extraction, toluene and pyridine high-temperature and high-pressure extraction technique were employed for the effective extraction of Tm@C-2n. The formation of Tm@C-2n was confirmed by LD-TOF and DEIMS characterization. The mass spectrometric results indicate that Tm@C-2n have a better solubility in toluene and worse solubility in pyridine than other metallofullerenes.

一种新型阻性板室（RPC）探测器的研制

气体探测器在核物理及粒子物理领域有着广泛的应用，尤其是阻性板室探测器，以其低廉的造价、优异的性能在各个大型实验室中都发挥着重要的作用。日本国家高能物理实验室(KEK)的Belle探测器，斯坦福大学斯坦福直线加速器中心(SLAC)的BaBar大型探测器，欧洲核子中心(CERN)的大型强子对撞机(LHC)的CMS与ATLAS谱仪，北京高能物理研究所(IHEP)的BESⅢ谱仪都使用阻性板室作为触发系统或缪子探测器。 随着HIRFL-CSR项目的完工。RIBLL2开展高能放射性束物理实验成为可能，而为了鉴别高能重离子碰撞实验中出射的高能轻粒子，有必要测量粒子的飞行时间(TOF)。为此，我们研制了单隙定时RPC，并作了简单性能测试。在CSR实验终端上，它可以作为传统塑料闪烁晶体+PMT时间探测器的替代，成为反应出射产物测量的大型探测器系统(4π)中的重要成员。 本论文对RPC的发展历史以及被广泛应用的原因做了深入而详细的研究，并对RPC的结构、性能、工作模式、特点、气体系统等进行了深入探讨。研制了一套单气隙RPC探测器样机，测设了一些相关性能，并对所遇到问题的产生原因以及解决方案进行了分析。为了测试RPC的需要，搭建了一套多组分工作气体配气系统，论文中还对包括质量流量计的选定，相关配件的选择，以及后期整个配气系统的组装与调试进行了详细描述

Biochemical and electron microscopic characterization of the F1F0 ATP Synthase from the hyperthermophilic eubacterium Aquifex aeolicus

The F1F0 ATP synthase has been purified from the hyperthermophilic eubacterium Aquifex aeolicus and characterized. Its subunits have been identified by MALDI-mass spectrometry through peptide mass fingerprinting and MS/MS. It contains the canonical subunits alpha, beta, gamma, delta and epsilon of F-1 and subunits a and c of F-0. Two versions of the b subunit were found, which show a low sequence homology to each other. Most likely they form a heterodimer. An electron microscopic single particle analysis revealed clear structural details, including two stalks connecting F-1 and F-0. In several orientations the central stalk appears to be tilted and/or kinked. It is unclear whether there is a direct connection between the peripheral stalk and the 6 subunit. (c) 2006 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.

海洋环境中有机锡的形态分析及其代谢降解研究

有机锡化合物被广泛用作塑料制品中的稳定剂、船舶油漆的防污剂、工业催化剂、农林业杀虫杀菌剂以及用于木材的防腐保存等，已经引起严重的环境污染。世界上许多国家纷纷制定相应的法规对其使用加以禁止或限制。我国目前还没有明确的限制有机锡使用的法律法规，缺少有机锡污染的第一手资料，更没有长期的控制、监测与研究计划。由于有机锡的种类繁多，理化性质存在差别，所以在提取、分离和测定中均存在较大的困难。从我国这方面己有的工作来看，缺乏各种高选择性的分离方法和高灵敏度的检测方法是制约这项研究广泛开展的原因之一。有机锡的痕量与超痕量分析技术是当今环境和食品安全分析领域的前沿技术。 本论文利用高效液相色谱和电感耦合等离子体质谱联用技术建立了海洋环境中多种有机化合物的同时快速检测方法；发展了多种海洋环境样品中有机锡的前处理技术；研究了有机锡在海洋生物中的分布、代谢及降解过程中化学形态的变化；同时发展了海洋环境中多种痕量元素的快速检测方法。所建立的高效液相色谱和电感耦合等离子体质谱联用技术可同时、快速分析5种有机锡的形态(三甲基锡TMT、二苯基锡DPhT、二丁基锡DBT、三丁基锡TBT和三苯基锡TPhT)，其检出限均低于0.3μg/L。 用所建立方法对南海海洋生物样品中的有机锡污染进行了研究，利用SPSS软件对检测结果进行了探讨，发现在所研究海洋生物样品的97.2%中可检出丁基锡和苯基锡化合物，其浓度分布处于该化合物检出限～1487.8ng/g范围内。其中，贝类样品中总有机锡的平均浓度为416.9ng/g，远远高于鱼类样品中总有机锡的平均浓度（211.9ng/g）。海洋生物中存在高浓度的有机锡说明本海域有机锡污染严重，已经对生态环境造成了严重影响，危害到人类生活。其主要的污染源是防污涂料的应用，目前紧迫的问题是采取必要的措施来控制有机锡的使用。 本工作建立了海水样品和沉积物样品中五种有机锡的简单快速萃取方法。采用加入2%的环庚三烯酚（tropolone）的二氯甲烷CH2Cl2对海水中的有机锡进行萃取，大大提高了有机锡的萃取率，减少了萃取的时间，二苯基锡（DPhT）、二丁基锡（DBT）、三丁基锡（TBT）和三苯基锡（TPhT）的萃取率均在80%以上，仅三甲基锡（TMT）的萃取率较低（在50%左右），究其原因，可能是因为在萃取的过程中三甲基锡（TMT）产生了降解。采用流动相和0.2%环庚三烯酚酮（tropolone）对沉积物国际标准物质PACS-2进行超声萃取及高速离心后，用所建方法进行了分析。结果表明，测定值与标准值吻合。研究表明，所建立的方法可用于实际环境沉积物中有机锡的形态分析。 本文建立了流动注射与电感耦合等离子体质谱联用技术直接同时测定海水中多种痕量元素的方法。该方法采用痕量进样技术，能够有效地减少海水中Na，Mg, Ca和Cl等大量基体元素对待测痕量元素测定的干扰，减少这些元素在电感耦合等离子体采样锥上的盐沉积，可以同时测量海水中的V、Cr、Mn、Fe、Co、Ni、Cu、Zn、As、Mo、Cd、Pb，Hg和U等痕量级元素。用所建的方法测定南海海域海水中的重金属元素，发现Cd，Cr，As等有毒有害元素的污染很轻，均符合Ⅰ级海水的限量。 在海洋沉积物样品处理研究中，本工作改进了不需要赶走HF酸就可以对沉积物消解完全的密闭容器消解法，由于减少了赶走HF酸的步骤，使消解的时间由原来的二十个小时降低为十个小时，大大降低了消解的时间。采用该样品消解方法，并用ICP-MS测定了南黄海海域沉积物中锡及其他重金属元素的含量。建立了微波消解-ICP-MS测定海洋生物中锡、砷、镉、汞及铅等有害重金属元素的分析方法，并用于南黄海7个及南海海域29个海产品中的测定。测定结果表明海洋生物中上述有毒有害元素有不同程度的超标问题；不同种类，不同产地的海洋生物中重金属元素的含量有一定的差别，这些研究结果为海产品安全质量控制提供了有价值的科学信息。 在上述各章工作的基础上，本文研究了有机锡在海洋生物中的分布、代谢及降解过程，并初步建立了高效液相-电喷雾-飞行时间质谱（LC-APCI-TOF-MS）测定有机锡的方法，可对未知的有机锡化合物进行结构表征。有机锡在贝类中不同的组织显示，其内脏中有机锡的含量高于肌肉中有机锡含量。常规的煮、炸、蒸及微波的烹饪方式并不能降解海产品中的有机锡化合物。

边坡动力响应分析及应用研究

As a marginal subject, dynamic responses of slopes is not only an important problem of engineering geology (Geotechnical problem), but also of other subjects such as seismology, geophysics, seismic engineering and engineering seismic and so on. Owning to the gulf between different subjects, it is arduous to study dynamic responses of slopes and the study is far from ripeness. Studying on the dynamic responses of slopes is very important in theories as well as practices. Supported by hundreds of bibliographies, this paper systemically details the development process of this subject, introduces main means to analyze this subject, and then gives brief remarks to each means respectively. Engineering geology qualitative analysis is the base of slopes dynamic responses study. Because of complexity of geological conditions, engineering geology qualitative analysis is very important in slopes stability study, especially to rock slopes with complex engineering geology conditions. Based on research fruits of forerunners, this paper summarizes factors influencing slopes dynamic stability into five aspects as geology background, stratums, rock mass structure, and topography as well as hydrogeology condition. Based on rock mass structure controlling theory, engineering geology model of the slope is grouped into two typical classes, one is model with obvious controlling discontinuities, which includes horizontal bedded slope, bedding slope, anti-dip slope, slide as well as slope with base rock and weathered crust; the other is model without obvious controlling discontinuities, which includes homogeneous soil slope, joint rock mass slope. Study on slope failure mechanism under dynamic force, the paper concludes that there are two effects will appear in slope during strong earthquake, one is earthquake inertia force, the other is ultra pore pressure buildup. The two effects lead to failure of the slope. To different types of slope failure, the intensity of two effects acting on the slope is different too. To plastic flow failure, pore pressure buildup is dominant; to falling rock failure and toppling failure, earthquake inertia force is dominant in general. This paper briefly introduces the principle of Lagrangian element method. Through a lot of numerical simulations with FLAC3D, the paper comprehensively studies dynamic responses of slopes, and finds that: if the slope is low, displacement, velocity and acceleration are linear enlarging with elevation increasing in vertical direction; if the slope is high enough, displacement, velocity and acceleration are not linear with elevation any more, on the other hand, they fluctuate with certain rhythm. At the same time, the rhythm appears in the horizontal direction in the certain area near surface of the slope. The distribution form of isoline of displacement, velocity and acceleration in the section of the slope is remarkably affected by the slope angle. In the certain area near the slope surface, isoline of displacement, velocity and acceleration is parallel to the surface of the slope, in the mean time, the strike direction of the extreraum area is parallel to the surface of the slope too. Beyond this area, the isoline direction and the strike direction of the extremum area turn to horizontal with invariable distance. But the rhythm appearing or not has nothing to with the slope angle. The paper defines the high slope effect and the low slope effect of slopes dynamic responses, discusses the threshold height H^t of the dynamic high slope effect, and finds that AW is proportional to square root of the dynamic elastic moduli El P , at the same time, it is proportional to period Tof the dynamic input. Thus, the discriminant of H^t is achieved. The discriminant can tell us that to a slope, if its height is larger than one fifth of the wavelength, its response regular will be the dynamic high slope effect; on the other hand, its response regular will be the dynamic low slope effect. Based on these, the discriminant of different slopes taking on same response under the same dynamic input is put forward in this paper. At the same time, the paper studies distribution law of the rhythm extremum point of displacement, velocity and acceleration, and finds that there exists relationship of N = int among the slope height H, the number of the rhythm extremum VHlhro) point N and ffthre- Furthermore, the paper points out that if N^l, the response of the slope will be dynamic high slope effect; \fN

Photodissociation of o-bromotoluene at 266 nm

The photodissociation of o-bromotoluene at 266 nm has been investigated using the universal crossed laser-molecular beam technique. The angle-resolved time-of-flight (TOF) spectra corresponding to Br photofragment are measured at different lab angles. The observed translational energy distribution and anisotropy parameters of the Br photofragment indicate that o-bromotoluene dissociates via two channels. In the first channel, the anisotropy parameter beta is determined to be 0.5 +/- 0.2 and the average translational energy is only 9% of the available energy. In the other photofragmentation channel, beta is determined to be - 0.4 +/- 0.2 and 44% of the available energy is assigned to translational energy. Possible mechanisms are discussed. (C) 1999 Elsevier Science B.V. All rights reserved.

Ammonia synthesis over Ru/C catalysts with different carbon supports promoted by barium and potassium compounds

Ammonia synthesis over ruthenium catalysts supported on different carbon materials using Ba or K compounds as promoters has been investigated. Ba(NO3)(2), KOH, and KNO3 are used as the promoter or promoter precursor, and activated carbon (AC), activated carbon fiber (ACF). and carbon molecular sieve (CMS) are used as the support. The activity measurement for ammonia synthesis was carried out in a flow micro-reactor under mild conditions: 350-450 degreesC and 3.0 MPa. Results show that KOH promoter was more effective than KNO3. and that Ba(NO3)(2) was the most effective promoter among the three. The roles of promoters can be divided into the electronic modification of ruthenium, the neutralization of surface functional groups on the carbon support and the ruthenium precursor. The catalyst with AC as the support gave the highest ammonia concentration in the effluent among the supports used, while the catalyst with ACF as the support showed the highest turnover-frequency (TOF) value. It seems that the larger particles of Ru on the carbon supports are more active for ammonia synthesis in terms of TOF value. (C) 2001 Elsevier Science B.V. All rights reserved.

Study on synthesis of azo-coupling products of 3-aminotropolone

3-Acetamidotropolone 1 reacted with p-substitutedbenzenediazonium chloride in pyridine to afford 3-acetamido-5-(4-substitutedphenylazo)tropolones 2a similar tof. Hydrolysis of compounds 2a similar tof gave 3-amino-5-(4-substitutedphenylazo)tropolanes 3a similar tof which could not be obtained directly from reactions of 3-aminotropolone with p-substitutedbenzenediazonium chloride. The structure of these new compounds 2a, 2c similar tof, 3a, 3c similar tof were confirmed from the elemental analysis and spectral data.

Carbon nanotubes as adsorbent of solid-phase extraction and matrix for laser desorption/ionization mass spectrometry

A method with carbon nanotubes functioning both as the adsorbent of solid-phase extraction (SPE) and the matrix for matrix assisted laser desorption/ ionization mass spectrometry (MALDI-MS) to analyze small molecules in solution has been developed. In this method, 10 muL suspensions of carbon nanotubes in 50% (vol/vol) methanol were added to the sample solution to extract analytes onto surface of carbon nanotubes because of their dramatic hydrophobicity. Carbon nanotubes in solution are deposited onto the bottom of tube with centrifugation. After removing the supernatant fluid, carbon nanotubes are suspended again with dispersant and pipetted directly onto the sample target of the MALDI-MS to perform a mass spectrometric analysis. It was demonstrated by analysis of a variety of small molecules that the resolution of peaks and the efficiency of desorption/ ionization on the carbon nanotubes are better than those on the activated carbon. It is found that with the addition of glycerol and sucrose to the dispersant, the intensity, the ratio of signal to noise (S/N), and the resolution of peaks for analytes by mass spectrometry increased greatly. Compared with the previously reported method by depositing sample solution onto thin layer of carbon nanotubes, it is observed that the detection limit for analytes can be enhanced about 10 to 100 times due to solid-phase extraction of analytes in solution by carbon nanotubes. An acceptable result of simultaneously quantitative analysis of three analytes in solution has been achieved. The application in determining drugs spiked into urine has also been realized. (C) 2004 American Society for Mass Spectrometry.

Quantitative determination of compounds in tobacco essential oils by comprehensive two-dimensional gas chromatography coupled to time-of-flight mass spectrometry

A quantitative analysis of the individual compounds in tobacco essential oils is performed by comprehensive two-dimensional gas chromatography (GC x GC) combined with flame ionization detector (FID). A time-of-flight mass spectrometer (TOF/MS) was coupled to GC x GC for the identification of the resolved peaks. The response of a flame ionization detector to different compound classes was calibrated using multiple internal standards. In total, 172 compounds were identified with good match and 61 compounds with high probability value were reliably quantified. For comparative purposes, the essential oil sample was also quantified by one-dimensional gas chromatography-mass spectrometry (GC/MS) with multiple internal standards method. The results showed that there was close agreement between the two analysis methods when the peak purity and match quality in one-dimensional GC/MS are high enough. (c) 2005 Elsevier B.V. All rights reserved.