MAT261数据采集时离子流强度的底限探测

The researched experiment of the limit ion intensity is finished in collecting data of isotope analysis on the MAT261.When ion intensity is more than 1.0 mV, a precise isotope ratio is gained if maintaining the stability of isotope ion current by strictly controlling electric current of vaporized strip and ionization strip. When ion intensity is between 1.0 mV and 0.5 mV, a reliable isotope ratio can be gained if maintaining the stability of isotope ion current by strictly controlling each step, increasing integral time and collecting data degree .When ion intensity is less than 0.5 mV, a accurate measure can not be done.     

千米桥古潜山岩溶岩及其地球化学特征

千米桥地区古岩溶岩的形态多种多样，根据国外岩溶角砾岩的分类三角图及鄂尔多斯盆地奥陶系岩溶岩分类方案，将其划分为岩溶残积岩、岩溶塌积岩、岩溶填积岩、岩溶淀积岩、岩溶溶蚀岩、岩溶交代岩、岩溶冲积岩和岩溶张裂岩等8类。在此基础上，通过微量元素、碳氧同位素分析及矿物流体包裹体的采样分析，认为：该地区古岩溶岩的形成过程极其复杂，是多期叠加的结果；在地质历史演化过程中，古岩溶岩先后经历了裸露期的风化壳岩溶、深埋藏期的热液岩溶和压释水岩溶。     

Accurate and precise determination of isotopic ratios by MC‐ICP‐MS: A review

For many decades the accurate and precise determination of isotope ratios has remained a very strong interest to many researchers due to its important applications in earth, environmental, biological, archeological, and medical sciences. Traditionally, thermal ionization mass spectrometry (TIMS) has been the technique of choice for achieving the highest accuracy and precision. However, recent developments in multi‐collector inductively coupled plasma mass spectrometry (MC‐ICP‐MS) have brought a new dimension to this field. In addition to its simple and robust sample introduction, high sample throughput, and high mass resolution, the flat‐topped peaks generated by this technique provide for accurate and precise determination of isotope ratios with precision reaching 0.001%, comparable to that achieved with TIMS. These features, in combination with the ability of the ICP source to ionize nearly all elements in the periodic table, have resulted in an increased use of MC‐ICP‐MS for such measurements in various sample matrices. To determine accurate and precise isotope ratios with MC‐ICP‐MS, utmost care must be exercised during sample preparation, optimization of the instrument, and mass bias corrections. Unfortunately, there are inconsistencies and errors evident in many MC‐ICP‐MS publications, including errors in mass bias correction models. This review examines “state‐of‐the‐art” methodologies presented in the literature for achievement of precise and accurate determinations of isotope ratios by MC‐ICP‐MS. Some general rules for such accurate and precise measurements are suggested, and calculations of combined uncertainty of the data using a few common mass bias correction models are outlined. © 2009 Crown in the right of Canada. Published by Wiley Periodicals, Inc., Mass Spec Rev 28:990–1011, 2009     

溶解无机碳在地下水中的应用

碳同位素广泛分布于自然界水体中,在降水、地表水、地下水相互转化过程中,同位素分馏作用导致不同水体中具有不同的同位素含量。本文就以位于不同碳酸盐地形的泉为例进行研究,确定区域所处的环境。     

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有机烷烃气碳同位素系列发生倒转的成因有:1.有机烷烃气和无机烷烃气的混合;2.煤成气和油型气的混合;3.“同型不同源”气或“同源不同期”气的混合;4.烷烃气中某一或某些组分被细菌氧化;5.地温增高。     

Parallel dynamic and kinetic regular triangulation in three dimensions

A parallel algorithm for regular triangulations is presented. For the purpose of fully dynamic and kinetic particle simulations it allows vertex insertion, deletion, movement, and weight changes. We describe new algorithms for incremental construction of regular triangulations, parallel vertex deletion and insertion. Finally, a parallel Lawson flip algorithm for vertex displacements is presented. The performance analysis demonstrates a significant parallel efficiency for various system sizes and performed changes.     

海拉尔盆地舒1井低蜡稠油成因及其意义

海拉尔盆地巴彦呼舒凹陷舒1井原油密度达0．932g／cm^3，但含蜡量仅为6％，属于低蜡稠油。原油中饱和烃含量仅30％左右，而非烃含量达30％以上；全油碳同位素组成很轻，δ^13C值分布为-34‰～-31‰；原油中类异戊二烯烷烃丰富，且以植烷占明显优势，Pr／Ph值小于0．9；甾烷组成中以ααα-20R构型甾烷为主，αββ构型异胆甾烷低，没有重排甾烷；萜烷组成以五环萜烷为主，三环萜烷含量低；含有丰富的伽马蜡烷和β-胡萝卜烷。原油的各种地球化学参数表明其属于低成熟原油，其成烃母质属于沉积于成水强还原环境的水生藻类有机质，是下白垩统南屯组烃源岩在低成熟阶段形成的产物。图4表1参8     

折叠波导行波管铪栅极退火温度及其性能

在充分考虑电子枪栅极的工作环境后,对铪(Hf)栅极进行了800、900和1000℃的真空退火处理,对其组织、织构特点进行了分析,并利用离子束辅助沉积技术在Ba-W阴极表面分别沉积金属钼膜和铪膜,以模拟栅控行波管中钼栅极和铪栅极表面吸附阴极蒸发物质时的表面状态,测试了这两种栅极表面“热电子发射”能力和“二次电子发射”系数.结果表明,随着退火温度的升高,铪(Hf)栅极的结晶度、晶粒尺寸增加,织构减少,铪的最佳退火温度为900℃,铪栅极表面吸附的阴极发射物质要远少于钼栅极,用金属铪作栅极材料能有效抑制栅电子发射.     

Revisiting the Mechanism of β-O-4 Bond Cleavage During Acidolysis of Lignin. Part 6: A Review

ABSTRACT

This paper reviews our results on the acidolysis of dimeric non-phenolic β-O-4-type lignin model compounds in aqueous 82% 1,4-dioxane containing an acid at 85°C. It was shown that the mechanism of a C₆-C₂-type model compound, 2-(2-methoxyphenoxy)-1-(3,4-dimethoxyphenyl)ethanol IX, is fairly different from that of a C₆-C₃ analogue, 2-(2-methoxyphenoxy)-1-(3,4-dimethoxyphenyl)propane-1,3-diol XX, suggesting the significance of the presence of the γ-hydroxymethyl group. It was confirmed that the hydride transfer mechanism exists as a reaction route of the benzyl-cation-type intermediates derived from both compounds, and the contribution of this mechanism is greater than expected in the acidolysis of compound XX. An enol ether compound, 2-(2-methoxyphenoxy)-3-(3,4-dimethoxyphenyl)prop-2-en-1-ol, was first detected in the acidolysis of compound XX using the DBr/D₂O/1,4-dioxane system. It was confirmed in the acidolysis of compound XX using HBr that the mechanism is different from that in the system using either HCl or H₂SO₄ and an unknown mechanism contributes to the reaction. This unknown mechanism surprisingly contributed more with decreasing concentration of HBr or Br^?, provided that Br^? still existed in the system.     

稳定同位素标记妥布特罗-D9的合成

以自制的叔丁胺-D9为同位素标记前体,以邻氯苯乙酮为起始原料,溴化后,再与叔丁胺-D9经胺化、硼氢化钠还原后得到稳定同位素标记布特罗-D9。采用均匀设计对胺化步骤进行研究,实验数据通过多元回归分析,得出了优化的工艺条件:反应温度59℃,反应时间5 h,三氯甲烷为25 m L,n(溴代酮)∶n(叔丁胺-D9)=1∶2。目标产物结构经质谱(MS)、核磁(NMR)、高效液相色谱(HPLC)表征,产物纯度高于98.0%,同位素丰度高于97.5%(atom D),可作为食品安全领域检测用同位素内标试剂。