ICP-AES测量指甲中5种微量元素

本文采用原子发射光谱法对人指甲中微量元素铜、钙、锰、铁、锌的含量测定进行了研究，本方法简单、快速、测定结果准确.相对标准偏差RSD＜2．51％。     

Einstein-aether theory with a Maxwell field: General formalism

We extend the Einstein-aether theory to include the Maxwell field in a nontrivial manner by taking into account its interaction with the time-like unit vector field characterizing the aether. We also include a generic matter term. We present a model with a Lagrangian that includes cross-terms linear and quadratic in the Maxwell tensor, linear and quadratic in the covariant derivative of the aether velocity four-vector, linear in its second covariant derivative and in the Riemann tensor. We decompose these terms with respect to the irreducible parts of the covariant derivative of the aether velocity, namely, the acceleration four-vector, the shear and vorticity tensors, and the expansion scalar. Furthermore, we discuss the influence of an aether non-uniform motion on the polarization and magnetization of the matter in such an aether environment, as well as on its dielectric and magnetic properties. The total self-consistent system of equations for the electromagnetic and the gravitational fields, and the dynamic equations for the unit vector aether field are obtained. Possible applications of this system are discussed. Based on the principles of effective field theories, we display in an appendix all the terms up to fourth order in derivative operators that can be considered in a Lagrangian that includes the metric, the electromagnetic and the aether fields.     

有限可修备件条件下系统计划更换策略

在现有的计划更换模型的基础上 ,研究了一种备件有限及部件可修的更换策略问题。利用在更换周期点上具有的马尔可夫性质 ,以系统首次故障前平均工作时间最大为目标建立了确定最佳更换周期的模型。     

LLT polynomials,chromatic quasisymmetric functions and graphs with cycles

We use a Dyck path model for unit-interval graphs to study the chromatic quasisymmetric functions introduced by Shareshian and Wachs, as well as unicellular LLT polynomials, revealing some parallel structure and phenomena regarding their $\mathrm{e}$-positivity.The Dyck path model is also extended to circular arc digraphs to obtain larger families of polynomials, giving a new extension of LLT polynomials. Carrying over a lot of the non-circular combinatorics, we prove several statements regarding the $\mathrm{e}$-coefficients of chromatic quasisymmetric functions and LLT polynomials, including a natural combinatorial interpretation for the $\mathrm{e}$-coefficients for the line graph and the cycle graph for both families. We believe that certain $\mathrm{e}$-positivity conjectures hold in all these families above.Furthermore, beyond the chromatic analogy, we study vertical-strip LLT polynomials, which are modified Hall–Littlewood polynomials.     

基于微区LIBS菊石化石中钙元素分布的研究

化石的研究可帮助科学家了解生物的演化进程,并帮助地质学家确定地层年代等地质信息,其中不同年代地层地质元素的变化是地质研究的热门课题。为研究不同年代地层地质元素的变化,搭建了一套微区LIBS实验系统,研究菊石化石中Ca元素的分布情况。采用非对称最小二乘法去除光谱数据的基线,并确定了最优的拟合参数。采用平均值归一化算法以减小光谱强度的相对标准偏差,多元线性回归算法计算模型的回归方程。首先,通过前期实验确定微区LIBS实验系统的最佳测试参数：激光波长为1 064 nm,激光脉冲频率为30 Hz,光谱仪采集延时为700 ns。其次,选取12块经过定量标定的天然岩石样品,从中随机抽取9块样品（闪长岩、闪长玢岩、辉长辉绿岩、粗玄岩、碱长粗面岩、角闪闪长岩、黑色浮岩、斑状角闪石花岗岩、玄武玻璃）作为测试集,其余3块样品（辉石闪长岩、辉石岩、斜长花岗岩）作为预测集。选取Ca Ⅱ 393.186 nm,Ca Ⅰ 422.856 nm,Ca Ⅰ 445.572 nm,Ca Ⅱ 559.031 nm,Ca Ⅰ 616.61 nm五个特征峰的谱线强度作为自变量,测试样品的实际Ca元素含量为因变量,利用多元线性回归算法建立Ca元素的定量分析模型,经预测集检验后得平均预测精度为92.9%。对表面经打磨的菊石化石进行5×5点阵扫描,得到一系列原子光谱数据。根据Ca元素的定量分析模型,计算后得到菊石化石Ca元素的横向分布图,其横向分辨率优于100 μm。作为纵向对比,选取每个测试点的第6,11和16组光谱数据进行处理,分别得到Ca元素的横向分布图。对比可以得到菊石化石Ca元素的纵向分布情况,结果表明菊石化石在平面和空间内均呈现不均匀分布的状态, 推测实验所选取的菊石化石在形成的过程中所处周围地层地质的元素及其含量是动态变化的。菊石化石不仅可以作为判定地层年代的证据,还可以通过对菊石化石的元素分布及含量的研究推测该化石所处地层的元素信息。研究工作对于浅海地层地质的演变、环境的变化具有一定指导意义。     

黄花倒水莲与六月雪中6种金属元素的测定

本文采用火焰原子吸收光谱法对中草药黄花倒水莲、六月雪中茎部的Ca、Zn、Mn、Mg、Fe、Cu的含量进行了测定,方法简单、精密度好,回收率在93%—100%之间,结果令人满意。     

胃康灵胶囊中15种元素含量分析

微波消解法制备供试品,电感耦合等离子体-质谱(ICP-MS)法测定中成药胃康灵胶囊中15种元素的含量,探讨其宏量、微量元素与疗效的关系。胃康灵胶囊中常量元素含量丰富,微量元素含量差别较大,Fe含量最多,Se含量最少,有害元素含量不高。胃康灵胶囊中元素与胃炎及胃溃疡的治疗密切相关。     

微波消解-火焰原子吸收光谱法测定蕨麻中8种矿物元素

利用微波消解,空气-乙炔火焰原子吸收光谱法对蕨麻中钾、钠、钙、镁、铜、锌、铁、锰8种人体必需矿物元素进行了测定。对样品的预处理方法、仪器的测定条件、共存元素的干扰及消除进行了研究,并对各测定元素进行了加标回收率实验。结果表明,在选定的实验条件下,该法的相对标准偏差均小于2.5%(n=8),各元素加标回收率为96.5%—103.2%。     

微波消解ICP-MS测定鲜竹笋中7种微量元素

建立同时检测鲜竹笋中铬、铜、锌、砷、镉、汞、铅等7种元素的分析方法。竹笋样品在硝酸介质中经微波消解,用电感耦合等离子体质谱(ICP-MS)检测,全定量法采集数据。校准曲线线性良好,相关系数在0.9937—1.0000之间;检出限为0.005—0.202μg/L;加标回收率在88.96%—110.5%;精密度RSD小于6.09%;国家标准样品西红柿叶(GSBZ51001-94)中几种元素的测定值都在标准范围内。该方法具有灵敏、可靠、快速、准确等优点,适用于竹笋中微量元素的分析测定。