积雪草总黄酮提取工艺和含量测定研究

确定积雪草总黄酮最佳提取工艺和含量测定方法,采用微波辅助法提取积雪草中的黄酮类化合物,通过正交实验确定了最佳提取工艺.分别以槲皮素和山奈酚为对照,采用紫外分光光度法在320nm处测定积雪草全草中的总黄酮.最佳工艺条件:提取次数3次,辐射时间20s,固液比1:10,功率480W.按最佳工艺条件提取总黄酮含量为8.40mg/g.回归方程为(槲皮素):y=29.993C+0.027,相关系数r2=0.9982,精密度和稳定性试验RSD分别为0.265%和0.172%(n≥6),平均加样回收率为99%,RSD=1.51%(n=5).回归方程为(山奈酚):y=36.928C+0.0178,相关系数rz=0.9991,精密度和稳定性试验的RSD分别为0.231%和0.190%(n≥6),平均加样回收率为99%,RSD=0.714%(n=5),样品的稳定性试验RSD为0.218%(60min).选择的最佳工艺对提取积雪草全草总黄酮确为最佳.用槲皮素或山奈酚标准品,采用紫外分光光度法,操作简便,结果准确,灵敏度高,重复性好,为积雪草全草中总黄酮含量测定的一种切实可行的方法.     

偏振光激发的Sr原子电偶极辐射

原子与激光场相互作用产生的自发辐射可以用经典电偶极辐射理论很好的描述.通过改变与Sr原子束相互作用激光的偏振方向,分析探测Sr原子束荧光强度的变化,测定了在远场区的电偶极辐射特性.Sr原子电偶极子在远场区辐射能量的空间方向分布满足sin2θ关系,利用这一规律可以有效地探测到最强的荧光光谱.     

Gravitational radiation of the Lemaître primordial atom

A non-traditional secondary quantizing of a strong gravitational field is realized. Using an earlier developed gravitational analog of the non-stationary perturbation theory it is shown that the Lema?tre primordial atom can generate hard gravitational radiation under spontaneous transitions of an effective Planckian particle in its discrete energy spectrum. Thus, the Lema?tre atom can be considered as a regular Big Bang model. Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 2, pp. 59–65, February, 2009.     

Influence of laser radiation on the Mössbauer absorption spectra of CdS (Fe<Superscript>57</Superscript>) single crystal

Influence of laser radiation on the resonant absorption of gamma radiation from Fe⁵⁷ nuclei in cadmium sulphide is investigated. It is shown that under action of laser radiation the shape of the Mössbauer spectrum of the sample is modified. The observed modification of the spectrum is explained by the presence in the sample of acoustic vibrations arising as a result of photoacoustic effect.     

Modification of Mössbauer reflection spectra of group AIIBVI single crystals with Fe<Superscript>57</Superscript> nuclei under influence of infrared radiation

Interaction of Mössbauer gamma radiation with ultrasound vibrations in group AIIBVI single crystals of CdS and CdSe with Fe⁵⁷ impurity nuclei under action of infrared radiation is investigated. It is shown that the infrared irradiation excites a phonon field in single crystals. Similar to the case of optical irradiation of single crystals the shape of their Mössbauer spectrum is modified. The effect of double modulation of resonant gamma radiation by infrared radiation has been observed.     

Investigation of nanostructured Fe3O4 polypyrrole core-shell composites by X-ray absorbtion spectroscopy and X-ray diffraction using synchrotron radiation

In this article, we focus on the structural peculiarities of nanosized Fe₃O₄ in the core-shell nanocomposites obtained by polymerization of conducting polypyrrole shell around Fe₃O₄ nanoparticles. The local structure of Fe atoms was determined from the Extended X-ray Absorption Fine Structure analysis using our own package computer programs. An X-ray diffraction method that is capable to determine average particle size, microstrains, as the particle size distribution of Fe₃O₄ nanoparticles is presented. The method is based on the Fourier analysis of a single X-ray diffraction profile using a new fitting method based on the generalized Fermi function facilities. The crystallites size obtained by X-ray diffraction spectra analysis was estimated between 3.2 and 10.3 nm. Significant changes in the first and the second Fe coordination shell in comparison with standard bulk were observed. The global and local structure of the nanosized Fe₃O₄ are correlated with the synthesis conditions of the core-shell polypyrrole nanocomposites.     

MOS结构电离辐射效应模型研究

基于氧化层空穴俘获和质子诱导界面陷阱电荷形成物理机制的分析,分别建立了MOS结构电离辐射诱导氧化层陷阱电荷密度、界面陷阱电荷密度与辐射剂量相关性的物理模型.由模型可以得到,在低剂量辐照条件下辐射诱导产生的两种陷阱电荷密度与辐射剂量成线性关系,在中到高辐射剂量下诱导陷阱电荷密度趋于饱和,模型可以很好地描述这两种陷阱电荷与辐射剂量之间的关系.最后讨论了低剂量辐照下,两种辐射诱导陷阱电荷密度之间的关系,认为低辐射剂量下两者存在线性关系,并用实验验证了理论模型的正确性.该模型为辐射环境下MOS器件辐射损伤提供了更 关键词： MOS结构 辐射 界面陷阱 氧化层陷阱     

论FeCr合金辐照损伤的多尺度模拟

铁素体/马氏体钢具有优异的抗辐照肿胀和抗腐蚀能力,是聚变堆、ADS和四代堆结构材料重要候选者之一.多尺度模拟在核武器自辐照损伤、压力容器辐照脆化、医学材料辐照损伤等方面有着广泛的应用.国际上围绕F/M FeCr合金辐照损伤开展了大量的多尺度模拟工作.论文概述了F/M FeCr合金辐照损伤多尺度模拟研究现状及进展,并针对目前存在的某些问题提出了解决建议. 关键词： 铁素体/马氏体FeCr合金 辐照损伤 多尺度模拟     

超强脉冲激光辐照固体靶背表面的渡越辐射

 在超强脉冲激光与固体靶相互作用中,利用光学CCD相机和光学多道分析仪,分别在固体薄膜靶背表面法线方向测量了渡越辐射（TR）积分成像图案和光谱。测量结果显示：TR空间分布图案呈圆环状,而辐射区域有发散角和光强分布;TR光谱在800 nm附近出现尖峰,是激光的基频波,这一现象归因于超热电子束在输运的过程中产生的微束团而引起的相干渡越辐射;如果考虑超热电子的产生和加热机制,共振吸收和真空加热对超热电子都有贡献,其中占主导地位的加热机制则是共振吸收对电子的加热。     

关节测量臂在上海光源元件标定中的应用

 关节测量臂以便携、高精度的小尺寸测量性能在上海光源的元件标定过程中得到了广泛应用。介绍了上海光源元件标定的方案设计,操作工艺以及质量保证措施等,着重探讨了关节测量臂的合理使用。在仪器使用过程中,利用软件的学习功能有效地提高了工作效率;通过将温度变化控制在2 ℃范围内,并利用标准尺及不同仪器的标定结果相互比较来控制、监测系统误差等,从而保证高精度的测量结果。