红外光谱结合化学计量学快速鉴别云南重楼不同炮制品

中药炮制是根据中医学理论,改变中药的性味和功效,以达到缓和药性、减毒增效等作用。炮制对中药的活性成分、药效、毒副作用影响甚大,建立一个系统鉴别和评价中药不同炮制品的方法,可为中药质量和临床用药安全提供重要支撑。采用红外光谱法对9种云南重楼不同炮制品进行对比分析,结合化学计量学建立主成分-马氏距离(PCA-MD)判别模型进行鉴别分析。云南重楼不同炮制品的红外光谱经自动基线校正和纵坐标归一化预处理后,取其平均光谱图。九种重楼不同炮制品的平均红外光谱和二阶导数光谱显示：(1)其主要特征吸收峰为3 387,2 923,1 745,1 463,1 338,1 240,1 207,1 158,1 180,1 080,1 048,1 020,988,921,895,859,833,765,708,572和529 cm-1;(2)重楼不同炮制品红外图谱的峰形基本相似,可显示出重楼所特有的红外光谱特征;(3)重楼不同炮制品红外图谱中少数特征吸收峰数目、位置和吸收强度存在差异,表明重楼经不同炮制后化学成分和含量发生了改变。红外光谱经多元散射校正(MSC),标准正态变量(SNV),一阶求导(1st Der),二阶求导(2nd Der)和平滑(SG)优化处理后,采用Kennard-Stone算法筛选训练集和预测集(3∶1),建立PCA-MD判别分析模型。结果显示,重楼不同炮制品的最佳预处理方法为1st Der+SG(11∶3)。提取前5个主成分,变量特征的解释能力为88.2%,以PC1,PC2和PC3为坐标轴建立PCA-MD三维得分图可知,九种炮制品可完全区分;其中重楼I,H,G和F的聚类效果最好,且前三种炮制品距离较近,表明晒干和烘干处理重楼与传统炮制重楼所含化学成分相似;重楼D和E空间距离较近,推测其经过微波和蒸汽高温处理后化学成分变化相似。预测集样本可准确的归属于训练集,PCA-MD判别模型的准确率为100%。红外光谱结合PCA-MD判别分析可准确区分云南重楼的不同炮制品,为云南重楼炮制品的临床应用提供参考,同时为中药炮制品的鉴别提供了借鉴。     

Dilatometric study of β-alumina single crystals

Single crystals of β-alumina exhibit an important dilatometric anisotropy. The anisotropic factor is about three for βNa-alumina. Variations of this factor are followed according to the nature of the conducting ion and the stoichiometry. The dilatometric behaviour of these compounds is explained (up to 800°C) from previous structural results.     

Finite-difference modeling à la Mickens of the distribution of the stopping time in a stochastic differential equation

Departing from a general stochastic differential equation with Brownian diffusion, we establish that the distribution of probability of the stopping time is governed by a parabolic partial differential equation. A particular form of the problem under investigation may be associated to a stochastic generalization of the well-known Paris’ law from structural mechanics, in which case, the solution of the boundary-value problem represents the probability distribution of the hitting time. An implicit, convergent and probability-based discretization to approximate the solution of the boundary-value problem is proposed in this work. Using a convenient vector representation of our scheme, we prove that the method preserves the most relevant properties of a probability distribution function, namely, the non-negativity, the boundedness from above by 1, and the monotonicity. In addition, we establish that our method is a convergent technique, and provide some illustrative comparisons against known exact solutions.     

近红外光谱快速鉴别不同产地药用植物重楼的方法研究

重楼属植物极具药用价值,野生资源主要分布在我国西南省区。应用近红外漫反射光谱,以贵州、广西和云南三个不同产区的70份野生药用植物重楼为研究对象进行产地鉴别。采用多元信号校正、标准正态变量、一阶导数、二阶导数、Norris平滑和Savitzky-Golay滤波六种方法,对训练集(50份样品)原始光谱进行优化处理。结果表明,多元信号校正结合二阶导数和Norris平滑预处理光谱效果最好。采用光谱标准偏差选择光谱波段(7 450~4 050cm-1),结合主成分-马氏距离(principal component analysis-mahalanobis distance,PCA-MD)建立分类模型,前三个主成分累计贡献率、R2、RMSEC和RMSEP分别为89.44%,97.58%,0.179 6,0.266 4,预测正确率90%;采用变量重要性图选择光谱波段(7 135.33~4 007.35cm-1),结合偏最小二乘判别分析法(partial least square discrimination analysis,PLS-DA)建立判别模型,前三个主成分累计贡献率、R2、RMSEC和RMSEP分别为89.28%,95.88%,0.234 8,0.348 2,预测正确率为100%。比较两种方法的结果可知:采用变量重要性图方法选择光谱波段结合偏最小二乘判别分析法建立的判别模型能更准确地鉴别不同产区的重楼,该方法的建立为中药材真伪和品质评价奠定基础。     

对裂纹扩展规律Paris公式物理本质的探讨

首先讨论了著名力学家K.Krausz和A.S.Krausz关于Paris公式物理本质研究的成果，从材料的微观结构和裂纹尖端的应力场出发，应用位错动力学理论，热激活能理论和速率过程理论对疲劳裂纹扩展规律进行了微观到宏观的探讨。最终推导出疲劳裂纹扩展速率的一个解析表示式，该式严格地定了Paris公式的两个试验常数，赋予了Paris公式明确的物理意义，从而真实地揭示了Paris公式的物理本质，为这一经验的普遍规律奠定了理论基础。     

A new spirostanol saponin from the rhizomes of Paris mairei

A new spirostanol steroidal saponin,named maireioside A(1),together with three known steroidal saponins,hypoglaucin G(2), parisaponin I(3),and diosgenin-3-O-α-L-rhamnopyranosyl(1→4)-[α-L-rhamnopyranosyl(1→2)]-β-D-glucopyranoside(4),were isolated from the rhizomes of Paris mairei.The structure elucidation was accomplished by 1D and 2D NMR methods,HR-ESI-MS, and hydrolysis.     

Heat distribution in Paris–Edinburgh press assemblies through finite element simulations

Knowledge on the temperature distribution in high pressure and temperature devices is important for the interpretation of data and can often not be obtained from experiments. Here, we report on the thermal characteristics of the most employed Paris–Edinburgh press assemblies for in-situ X-ray purposes using finite element calculations. The maximal horizontal T variations in the sample are found to be small and amount maximal 50?K at 2500?K. Temperature differences between the sample and the calibrant material are in the same order of magnitude only if the latter is placed well centred on the sample capsule. The present (pure thermal) calculations can only partly reproduce the discrepancies between experimentally determined input power to T relations (1000?K at 350?W) indicating that different deformation behaviours of assemblies may play a crucial role. Based on the obtained results we present an optimized assembly in terms of sample temperature and gradients.     

A classification of rapidly growing Ramsey functions

Let be a number-theoretic function. A finite set of natural numbers is called -large if . Let be the Paris Harrington statement where we replace the largeness condition by a corresponding -largeness condition. We classify those functions for which the statement is independent of first order (Peano) arithmetic . If is a fixed iteration of the binary length function, then is independent. On the other hand is provable in . More precisely let where denotes the -times iterated binary length of and denotes the inverse function of the -th member of the Hardy hierarchy. Then is independent of (for ) iff .

     

Evidence for the Bφ decay mode of the ω(1670)

Backward production of ω(1670) is observed in the reactions K^?p→φ⁺φ^?ω⁰Λ⁰ and K^?p→φ⁺φ^?φ⁰φ⁰ for |U'_Λ|<1.0 GeV². The cross section for the ω(1670) →φ⁺φ^?ω⁰ decay mode is 1.90±0.35 μb for 8.25 GeV/c incident K^?. Evidence is presented for the importance of the sequential decay, ω(1670) → Bφ → ωφφ with a branching ratio ω(1670) → Bφ/all ω(1670) → ωφφ=1.0±_0.25^0.00.     

Separation and identification of steroidal compounds with cytotoxic activity against human gastric cancer cell lines <Emphasis Type="Italic">in vitro</Emphasis> from the rhizomes of <Emphasis Type="Italic">Paris polyphylla</Emphasis> var. <Emphasis Type="Italic">chinensis</Emphasis>

A novel steroidal saponin, along with 12 known steroidal compounds, was isolated from the rhizomes of Paris polyphylla var. chinensis. Spectral data, including two-dimensional NMR, showed that the structure of the novel saponin was 3β,21-dihydroxypregnane-5-en-20S-(22,16)-lactone-1-O-α-L-rhamnopyranosyl(1→2)-[β-D-xylopyranosyl(1→3)]-β-D-glucopyranoside. The isolated steroidal compounds were evaluated for their cytotoxic activity on human gastric cancer cell line HepG₂, SGC7901, BxPC3. Diosgenin-3-O-α-L-rhamnopyranosyl(1→2)[α-L-rabinofuranosyl(1→4)]-β-D-glucopyranoside exhibited the most potent cytotoxic activity among the isolated steroids. Published in Khimiya Prirodnykh Soedinenii, No. 6, pp. 556–560, November–December, 2007.