X衍射指纹图谱及相似度分析用于鉴别野生和栽培天麻

用X射线粉末衍射法建立了野生和栽培天麻及伪品羊角天麻的指纹图谱。通过数字信号处理技术提取天麻样品的特征信息,按2θ进行相似度计算和分析。天麻的XRD指纹图谱呈多峰重叠的弥散性峰,识别图谱的整体轮廓能区分真伪天麻。野生与栽培天麻的差异主要是2θ在5～10°和30～50°间,通过数字信号处理技术提取低频信号,能有效鉴别野生和栽培天麻。相似度的计算结果进一步表明方法的可行性。     

粉末X射线衍射结构分析的进展

粉末X射线衍射结构分析自Rietveld 1967. 1969年在中子粉末衍射结构分析中问世后,又经Wiles and Young 1981、1982年介绍到X射线衍射技术中来,近几年来取得了显著的进展。特特是同步辐射光源的建成和应用,取得了和单晶结构分析几乎同样等级的拟合程度和极为相似的结构参数。本文就近几年来粉末X射线衍射对晶体结构分析方面的进展进行综述,着重讨论Bragg衍射的峰形函数,择优取向校正和光学系统改善等方面对结构精化的影响,介绍在某些方面中的应用。     

原位磁场下粉末样品的X射线衍射图谱

To obtain more crystal and magnetic structural information of powder crystals,magnetic field is introduced into X'Pert-MPD XRD apparatus with the strength of 0. 42 T and two different directions:one direction of magnetic field is vertical to the sample holder and another is parallel. XRD patterns in situ magnetic field are obtained for six samples which are representative of paramagnetic,diamagnetic,ferromagnetic,ferrimagnetic,antiferromagnetic substances and reduction product of FeCl2 by NaBH4 respectively. Compared with XRD patterns obtained in the zero magnetic field,there are some diffraction peaks disappear,some occur,or some diffraction angles and counts change. In addition,the patterns are different under the different direction of magnetic field. The cause is that magnetic dipoles in crystals are oriented along with the direction of magnetic field. The oriented magnetic dipoles produce stress in crystals and make crystal lattice changed（such as magnetostriction）or even turn particles aligned along with the direction of magnetic field to form preferred orientation of particles.     

L-精氨酸·氟硼酸加合物的X射线粉末衍射分析

采用X射线粉末衍射法对L-精氨酸·氟硼酸加合物进行了分析.数据收集范围在2θ角从7°到80°(共64个观测点).采用最小二乘法对该加合物粉末衍射的晶胞参数进行了计算,实验表明:该加合物为正交晶系,空间群P212121,晶胞参数a=0.50702(6)nm,b=1.37288(12)nm,c=1.64880(15)nm,V=1.147713nm3;Z=4;ρ=1.52g/cm3,粉末衍射分析的结果与单晶结构数据相吻合.     

面粉中滑石粉的X射线衍射分析

通过四氯化碳分离或高温灰化,X射线衍射分析测定面粉中掺入的滑石粉。其中灰化处理适宜温度为500~750℃。该方法简便、快速,灵敏度高,样品用量少,准确可靠,可推广为检测面粉质量的一种较理想的手段。     

中药板蓝根的化学振荡指纹图谱研究

采用振荡技术,研究了中草药及中成药板蓝根-丙酮-溴酸钾-硫酸锰-硫酸的振荡反应新体系的振荡指纹图谱.测定了不同浓度,不同温度下板蓝根的振荡反应图谱,得到了不同温度、浓度下的反应诱导期、振荡周期及振荡寿命,得出诱导期表观活化能Ein=135.054kJ/mol,振荡周期平均活化能Ep=71.802kJ/mol;初步研究此...     

中国茜草与欧茜草的X射线粉末衍射分析

对植物中国茜草（ＲｕｂｉａｃｏｒｄｉｆｏｌｉａＬ．）和欧茜草（Ｒ．ｔｉｎｃｔｏｒｕｍ）首次采用Ｘ射线粉末衍射分析方法进行了鉴定研究,获得令人满意的结果。该法快速、准确、重现性好,样品前处理简单易行     

高效液相色谱指纹图谱应用于板蓝根的鉴定

利用高效液相色谱建立了板蓝根的色谱指纹图谱。采用反相C18柱，流动相为水：甲醇（V/V=96：4），检测波长为260nm；流速1.0mL/min进行试验。根据相对保留值a和相对面积Sr对色谱指纹图谱进行分析对比研究，建立了一个快速、简易鉴别板蓝根样品的色谱指纹图谱分析方法。该法为中药样品的鉴定提供了较全面的信息，并为HPLC在复杂组分的样品分析和鉴别领域开拓了新的应用。     

X射线衍射定量相分析新方法

在基体清洗法的基础上提出一种新的X射线衍射定量分析方法，该方法是利用混合样品X射线衍射谱图中的全部衍射峰数据，把清洗剂同样品中所包含的所有待测物相的纯相按比例混合，在同一水平下同时测定各物相与清洗剂对应的几个K值，结合JCPDS卡中的各相标准谱峰的相对强度分布数据进行最小二乘方程组的抛弃平均法回归分析，求得混合物样品中各相间的全谱峰匹配强度比，用于混合物样品的X射线衍射定量相分析，有利于提高定量相分析的精度，通过对四组分混合物样品的分析，实验结果和理论完全一致。     

X-Ray Diffraction Study of Piperidine Octamolybdate

Piperidine octamolybdate [C₅H₅NH₂]₄[Mo₈O₂₆]·4H₂O (I) has been synthesized and characterized by X-ray diffraction analysis. Crystals I are monoclinic, space group P2₁/n, a=12.892(3), b=9.283(2), c=19.184(4) , =92.50(3)°, V=2293.7(9) ³, Z=2,_calc = 2.317 g/cm³.     

Short-Range Ordering in Liquid Bicyclohexyl by X-Ray Diffraction

Abstract

The paper reports results of the X-ray diffraction structural studies of liquid bicyclohexyl, C₆H₁₁—C₆H₁₁ at room temperature, using CuK _α radiation. Angular distribution of X-ray scattered intensity was measured, and the electron-density radial-distribution function was calculated. Computer techniques were used to minimize the effects of experimental errors, uncertainties in the scattering factors, and termination errors. Good agreement between the theoretical and experimental functions was obtained on assuming the statistically most probable model of this molecule. The structural data obtainable by X-ray analysis for liquid bicyclohexyl were discussed. The mean distances between the neighbouring molecules and the radii of coordination spheres were found. The maxima in the differential radial distribution function were at: r ₁ = 4.68, r ₂ = 5.57, r ₃ = 6.62, r ₄ = 8.05 Å. X-ray structural analysis was applied to determine the packing coefficient of bicyclohexyl molecules. A simple model of short-range arrangement of the molecules in liquid bicyclohexyl was proposed.     

Identification of Composite Cement Hydration Products by Means of X-Ray Diffraction

 In this paper the effect of limestone, fly ash, slag and natural pozzolana on the cement hydration products is studied. Four composite cements containing limestone, natural pozzolana from the Milos Island, slag and fly ash have been produced by intergrinding clinker (85%), the above main constituent (15%) and gypsum. The grinding process was designed in order to produce cements of the same 28d compressive strength. The hydrated products, formed after 1–28 days, were studied by means of X-ray diffraction. Unhydrated calcium silicate compounds of clinker and hydration products such as C*H, C*S*H and ettringite are clearly observed. Although there is not significant differentiation among samples hydrated for the same period of time, modifications of calcium aluminate hydrates as well as sulfoaluminate hydrates, are indicated by the XRD patterns. In samples of limestone cement, monocarboaluminate is formed in the first 24 hours and is still present after 28 days.     

用热重分析与X-射线衍射法探究中国花鲈耳石的微结构

为表征中国花鲈耳石的微结构,应用数码照相机、热重分析仪与X-射线衍射仪对中国花鲈耳石的外观形貌、化学组成与晶体结构进行记录及表征。结果显示:中国花鲈耳石为较厚的宽叶形,表面有不同大小的晶状突,边缘有叶形晶状突,内弯面有中央突,弯曲背面有嵴突及几乎贯穿整个耳石的主凹槽;TGA曲线分为晶体间隙水的挥发,有机质和无机盐的灰化与分解,碳酸钙热分解为氧化钙等三个平台,化学组成中碳酸钙含量为97.92%,水、有机质和其它无机盐含量为2.08%;XRD晶体结构属于稳定性较差的含很少量第二相的霰石。组成与结构的表征有助于鱼类耳石的化学生物学分类数据库的建立,也丰富了耳石的研究内涵。     

Statistical Inference of Distribution of Crystal Size by X-Ray Powder Diffraction

We describe a method to calculate the distribution of sizes of fine crystals from pure powder-diffraction profile using a method of maximum entropy (MAXENT). We apply a Monte-Carlo technique of simulated annealing to seek a global minimum of the error surface in fitting this diffraction profile. We consider pure diffraction profile (instrument de-convoluted) of a powder specimen without lattice imperfection to a significant extent. Under these circumstances, the distribution of the pure diffraction profile can be attributed to the distribution of crystallite size. We applied this method to three cases of crystal sizes having a highly inhomogeneous distribution with certain noise-tolerance. The results agree well with synthetic data of diffraction.     

PA6／PET共混体系的X射线衍射分析

用宽角Ｘ射线衍射分析,考察尼龙６／ＰＥＴ共混体系的结晶态,表明在共混物中尼龙６和ＰＥＴ是各自结晶的,即晶相分离的。研究了结晶条件,组份比等对晶态结构的影响,发现共混体系相对结晶度低于纯组份的算术加和,说明共混体系的结晶相分离过程中,由于存在相互作用导致的干扰,使结晶度下降。     

长链脂肪酸LB膜的X射线衍射研究

利用Langmuir-Blodgett技术制备了硬脂酸、花生酸及其混合酸的多层LB膜。用低角X射线衍射研究了它们的周期结构,硬脂酸和花生酸的LB膜在2θ=0.8°～23°的范围内分别出现13个和12个布拉格衍射峰,由此计算了它们的等同周期。用模型计算了它们衍射峰的强度,得到了与实验一致的衍射强度奇偶起伏的结果。在混合酸的LB膜中,可以观察到等同周期随混合比变化的规律。     

X-Ray Diffraction Study of Some Liquid Naphthalene Derivatives

Abstract

The structure of the liquids 1-Methylnaphthalene C₁₀H₇—CH₃ and 1-Chloronaphthalene C₁₀H₇—Cl was investigated using X-ray diffraction at 293 K. Monochromatic radiation MoK_α (λ = 0.7107Å) enabled determination of the scattered radiation inteasity between S₀ = 4pi sin υ₀/λ = 0.430 Å^?1 and S _max = 14.311 Å-1. Angular distributions of X-ray scattered intensity were measured, and differential radial distribution functions of electron density (DRDFs) were calculated. The mean distances between the neighbouring molecules and the ranges of the spheres of intermolecular ordering were found. X-ray structural analysis was applied for determination of the packing coefficient of molecules of the liquids studied. A simple model of short-range arrangement of the molecules was proposed, which seems to be valid for other weakly polar monosubstituted naphthalene derivatives in the liquid phase.     

Picosecond Time Resolved Hard X-Ray Diffraction from Laser Heated Metallic Crystals

We report the development of a novel hard X-ray diffraction system with picosecond time resolution. Picosecond X-ray pulses are produced by excitation of an X-ray diode with picosecond ultraviolet light pulses at a repetition rate of 300 Hz. The X-ray pulses are synchronized to the optical pulses with picosecond accuracy. The system has been utilized in picosecond time resolved X-ray diffraction of laser pulse heated gold and platinum single crystals.