Average‐atom model calculations of dense‐plasma opacities: Review and potential applications to white‐dwarf stars

Methods using average‐atom models in order to calculate dense‐plasma opacities and conductivities are reviewed. Dense plasmas at moderate temperatures, of interest in white‐dwarf modelling, are considered. Due to their relative simplicity of implementation, compared to more detailed models (detailed‐level accounting, detailed configuration accounting, etc.), average‐atom models are a privileged framework for the application of the most involved dense‐plasma statistical modelling. Moreover, the average‐atom models are well suited to the calculation of some thermodynamic properties, such as the equation of state. They can also be used in order to estimate broadband radiative properties of dense plasmas. After an introduction to the opacity issue in the modelling of white dwarfs, we make a short review of average‐atom models. We then address the methods of calculating the opacity starting from the average‐atom model, see some of their limitations, and briefly discuss some problems that remain open, such as the modelling of fluctuations, or the accounting for channel mixing and collective phenomena in the photoabsorption.     

不同微波条件对蛋清蛋白糖基化产物不均匀性的影响

实验研究微波对蛋清蛋白粉与葡萄糖干样混合体系的影响,构建微波条件下蛋清蛋白-葡萄糖圆柱体反应模型。通过改变微波的功率,时间和位置,采用红外热像仪、荧光、紫外,高效液相色谱等方法研究微波场中蛋清蛋白糖基化产物不均匀性。将蛋清蛋白粉末与葡萄糖等质量混合,手工震荡和研钵充分研磨后在平皿表面铺一薄层粉末,放置于微波炉中心反应。将反应后的样品按左、中、右分成三个规则区域均匀采样。热像图表明微波功率越高,样品表面温度越高。凝胶电泳图表明240 W微波加热30 min样品边缘已经发生了反应,而且样品中间部分几乎还未反应;自由氨基含量测定表明高功率长时间微波作用才会观测到明显糖基化反应而低功率短时间条件下反应不明显,且边缘部分的样品反应总是比中间部分的样品剧烈;通过荧光光谱可知,蛋清蛋白和葡萄糖发生了反应,而样品边缘部分荧光强度降低得比样品中间部分多说明样品边缘反应更加剧烈;紫外光谱测定表明越剧烈的微波条件样品紫外吸收越多,边缘部分紫外吸收最高。液相结果也证实了这一点,糖基化样品边缘部分5-羟甲基糠醛(HMF)含量明显高于样品中间部分,且随时间和功率逐渐增加。     

多个(重)强峰压制与白酒的核磁共振分析

利用激发塑型（excitation sculpting）方法,结合多频率选择性激发的形状脉冲（shapedpulse）、13^C CPD去偶和修整脉冲（trimpulse）等手段进行多个（重）强峰的压制,测试了市售白酒的各种1^H核磁共振谱图,并根据样品性质对脉冲序列中的各种参数进行了优化。在压制了其中水和乙醇峰后得到的一维、二维谱图中,清晰地呈现了各个微量组分的谱峰以及反映各组：分化学结构的相关峰,据此对图谱中各个谱峰进行了指认。实验表明这种方法对酒类产品的分析研究非常有效,可以应用于酒类生产和储存过程的质量控制、产品的真假及产地的鉴别等。     

红色荧光粉Na8.33 La1.67(SiO4)6 O2:Eu3+的制备及发光特性

采用高温固相法制备了Na_(8. 33)La_(1. 67)(SiO_4)_6O_2∶Eu~(3+)红色发光材料,利用X射线衍射仪测定其晶体结构,利用Hitachi F4600表征其发光光谱。在紫外光激发下,样品Na_(8. 33)La_(1. 67)(SiO_4)_6O_2∶Eu~(3+)呈多峰发射,分别对应于Eu~(3+)的~5D_0-~7F_j(j=0,1,2,3,4)能级跃迁,主峰是位于615 nm的~5D_0-~7F_2跃迁发射。研究了Eu~(3+)掺杂浓度对材料发光性质的影响,改变Eu~(3+)掺杂浓度,样品的发射强度随之改变,Na_(8. 33)La_(1. 67)(SiO_4)_6O_2∶Eu~(3+)材料的Eu~(3+)浓度为15%时,发光强度最大。讨论了浓度猝灭的机理,理论计算表明引起Eu~(3+)离子能量弥散的主要原因是离子间交换相互作用。     

湖田窑宋代青白瓷的组成及呈色特征

景德镇宋代以生产青白瓷而闻名,其中湖田窑又是景德镇宋代窑址中最典型的一处,其生产的青白瓷精巧细致,有“假玉器”和“饶玉”之称。研究采用能量色散X荧光光谱分析仪和色差计,分析了湖田窑宋代青白瓷的胎、釉化学组成和色度值,初步探讨了不同时期青白瓷的组成、配方和呈色特征。研究表明,湖田窑北宋和南宋青白瓷胎体组成特征基本一致,均与当地瓷石原料较为接近,极有可能采用了附近的三宝瓷石原料制胎。瓷釉组成结果显示釉中含有较高的CaO和一定量的MnO和P₂O₅,表明湖田窑青白瓷釉为“钙釉”,且釉料配方中引入了一定量的草木灰。色度分析结果显示,湖田窑北宋和南宋青白瓷釉主波长分别为500和496 nm左右,均落在可见光波的绿色波段。但对比北宋和南宋瓷釉组成和色度结果发现,北宋青白瓷釉无论是组成还是色度数据结果均较南宋更为分散,且南宋青白瓷釉层呈色相较北宋样品b值更小,釉色更为偏蓝。研究认为,湖田窑青白瓷从北宋至南宋,釉料配方经历了从探索逐渐走向成熟、稳定的过程。研究结果不仅为景德镇湖田窑青白瓷的断源断代提供了数据支撑,也为湖田窑青白瓷制瓷技艺的传承和传播提供了一定的科学素材。     

Interacting Fock Expansion of Lévy White Noise Functionals

Consider the Lévy white noise space (S ^*,(S ^*),), where S ^* is the Schwartz distributions over R ^d and is a Lévy white noise measure lifted from a 1-dimensional infinitely divisible distribution with finite moments. We give explicit forms and recursion formulas of moment and renormalization kernels for the Lévy white noise measure. By defining inner products (,)_[n] in n-particle spaces, we establish an interacting Fock space _n=0 ⁽ⁿ⁾ and the interacting Fock expansions for Lévy white noise functionals. The usual Fock space (H)= _n=0 can be viewed as a quotient space of the interacting Fock space. As a particular case, we give the interacting Fock expansion for gamma white noise functionals.     

White Noise of Poisson Random Measures

We develop a white noise theory for Poisson random measures associated with a pure jump Lévy process. The starting point of this theory is the chaos expansion of Itô. We use this to construct the white noise of a Poisson random measure, which takes values in a certain distribution space. Then we show, how a Skorohod/Itô integral for point processes can be represented by a Bochner integral in terms of white noise of the random measure and a Wick product. Further, based on these concepts we derive a generalized Clark–Haussmann–Ocone theorem with respect to a combination of Gaussian noise and pure jump Lévy noise. We apply this theorem to obtain an explicit formula for partial observation minimal variance portfolios in financial markets, driven by Lévy processes. As an example we compute the closest hedge to a binary option.     

Exact constants for pointwise adaptive estimation under the Riesz transform

We consider nonparametric estimation of a multivariate function and its partial derivatives at a fixed point when the Riesz transform of the function is observed in Gaussian white noise. We assume that the unknown function belongs to some Sobolev class and construct an estimation procedure which achieves the best asymptotic minimax risk when the smoothness of the function is unknown.Writing of this article was financed by Deutsche Forschungsgemeinschaft under project MA1026/6-2 and Rolf Nevanlinna Institute.Mathematics Subject Classification (2000): 62G05, 62G20     

基于WLI原理K9基片的亚表层损伤检测

在现代激光技术的应用发展中，光学元件在其制造过程中形成的亚表层损伤是导致激光损伤的主要根源之一。光学元件亚表层的检测方法已成为光学加工领域的一个新的热点问题。利用非接触式白光干涉原理对K9基片进行亚表层损伤检测，获得基片表面至亚表面200μm深的三维立体图和纵向截切图，并精确地确定其亚表层损伤深度，以及在不同深度范围内的损伤密度。该方法与现阶段国内常用的亚表层损伤检测方法相比，具有非破坏性、纵向检测结果精确、检测过程简单快捷等特点。     

Chaos Expansion of Heat Equations with White Noise Potentials

The asymptotic behavior as t of the solution to the following stochastic heat equations