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61.
采用超高效液相色谱-四极杆飞行时间高分辨质谱(UPLC-QTOFMS)联用技术, 对血清前处理进行了考察和优化, 并对液-质联用分析条件进行了优化, 旨在建立用于血清中广谱小分子代谢物分析的高通量强耐用代谢组学方法, 以期满足大批次生物样本数代谢组学研究的要求(样本数≥400个). 通过考察不同有机溶剂沉淀蛋白对血清中蛋白的去除程度及38个代表性标准品化合物的提取效果, 确定采用甲醇/乙腈(体积比1: 9)沉淀蛋白法. 血清和有机溶剂的体积比不小于1: 4时, 达到最佳的沉淀蛋白处理效果, 符合大批量样本测试的要求; 预先冷藏沉淀蛋白的有机溶剂, 涡旋2 min, 超声1 min, 加入有机溶剂后冷冻静置10 min, 可以进一步提高前处理沉淀蛋白和化合物提取的效果. 通过对不同流动相体系和梯度条件的考察, 对液-质联用分析条件进行了优化. 方法学考察结果表明, 本方法重现性、 精密度及稳定性均良好. 对重现性和48 h稳定性数据进行变异系数分析和主成分分析法的多维分析, 证明本方法在代谢组学研究中的可重复性及所得数据的可靠性. 本方法高通量强耐用, 每天可测定100多个血清样本(13 min测定1个样本), 适用于代谢组学研究, 特别是大批次生物样本的代谢组学研究. 相似文献
62.
The influences of thickness of spacing layer and the elastic anisotropy on the strain fields and band edges of InAs/GaAs conical shaped quantum dots 下载免费PDF全文
Based on the continuum elastic theory, this paper presents a finite
element analysis to investigate the influences of elastic anisotropy
and thickness of spacing layer on the strain field distribution and
band edges (both conduction band and valence band) of the InAs/GaAs
conical shaped quantum dots. To illustrate these effects, we give
detailed comparisons with the circumstances of isolated and stacking
quantum dot for both anisotropic and isotropic elastic
characteristics. The results show that, in realistic materials
design and theoretical predication performances of the
optoelectronic devices, both the elastic anisotropy and thickness of
the spacing layer of stacked quantum dot should be taken into
consideration. 相似文献
63.
Approximate calculation of electronic energy levels of axially symmetric quantum dot and quantum ring by using energy dependent effective mass 下载免费PDF全文
Calculations of electronic structures about the semiconductor
quantum dot and the semiconductor quantum ring are presented in this
paper. To reduce the calculation costs, for the quantum dot and the
quantum ring, their simplified axially symmetric shapes are utilized
in our analysis. The energy dependent effective mass is taken into
account in solving the Schr?dinger equations in the single band
effective mass approximation. The calculated results show that the
energy dependent effective mass should be considered only for
relatively small volume quantum dots or small quantum rings. For
large size quantum materials, both the energy dependent effective
mass and the parabolic effective mass can give the same results. The
energy states and the effective masses of the quantum dot and the
quantum ring as a function of geometric parameters are also
discussed in detail. 相似文献
64.
This paper presents a detailed analysis of the dependence of
degree of strain relaxation of the self-organized InAs/GaAs quantum
dot on the geometrical parameters. Differently shaped quantum dots
arranged with different transverse periods are simulated in this
analysis. It investigates the total residual strain energy that
stored in the quantum dot and the substrate for all kinds of quantum
dots with the same volume, as well as the dependence on both the
aspect ratio and transverse period. The calculated results show that
when the transverse period is larger than two times the base of the
quantum dots, the influence of transverse periods can be ignored.
The larger aspect ratio will lead more efficient strain relaxation.
The larger angle between the faces and the substrate will lead more
efficient strain relaxation. The obtained results can help to
understand the shape transition mechanism during the epitaxial
growth from the viewpoint of energy, because the strain relaxation
is the main driving force of the quantum dot's self-organization. 相似文献
65.
多工序制造过程通常包含串联和并联两种结构,具有串并联混合结构的多工序制造过程是实践中最为常见的形式,而不同模式的并联结构其上游工序质量波动对下游工序及总过程能力的影响不同。针对多工序制造过程并联结构特点,本文从波动减少的角度重点对多工序并联制造过程中并行、分散和收敛三种基本模式进行过程能力分析,研究多工序制造过程中各子过程波动对整体过程能力的影响,并根据各子过程质量波动减少的“困难度”和“效用比”评价质量改进的效果,给出多工序并联过程能力改进策略选择依据。通过实例表明,本方法能较好地识别各工序质量波动减少对本工序过程能力和总过程能力的不同影响,确定质量改进的优先顺序,实现多工序制造过程的经济性质量改进和优化。 相似文献
66.
We theoretically analyze the steady state emission spectrum and transient temporal dynamics in a coupled biexciton quantum dot(QD)–cavity system. For steady state, a phonon-assisted biexciton–exciton cascade model under continuous wave(CW) excitation is presented to explain the asymmetric QD–cavity emission spectrum intensities(intensities of cavity,exciton, and biexciton emission peak) in off-resonance condition. Results demonstrate that the electron–phonon process is crucial to the asymmetry of emission spectrum intensity. Moreover the transient characteristics of the biexciton–exciton cascade system under pulse excitation show abundant nonlinear temporal dynamic behaviors, including complicated oscillations which are caused by the four-level structure of QD model. We also reveal that under off-resonance condition the cavity outputs are slightly reduced due to the electron–phonon interaction. 相似文献
67.
We present equilibrium composition maps in InGaAs/GaAs conic strained quantum dots, using the finite element method and quadratic programming optimization method. The axis-symmetric model is adopted. We compare the steep islands with the shallow islands and determine the influence of entropie energy. The difference of equilibrium composition maps between the single dot and the quantum dot stacks is also discussed. 相似文献
68.
69.
变量选择控制图是高维统计过程监控的重要方法。针对传统变量选择控制图较少考虑高维过程空间相关性而造成监控效率低的问题,提出一种基于Fused-LASSO的高维空间相关过程监控模型。首先,利用Fused LASSO算法对似然比检验进行改进;然后,推导出基于惩罚似然比的监控统计量;最后,通过仿真模拟和真实案例分析所提监控模型的性能。仿真实验和真实案例均表明:在高维空间相关过程中,当相邻监控变量同时发生异常时,利用所提监控方法能够准确识别潜在异常变量,取得较好的监控效果。 相似文献
70.