蛛丝和蚕丝化学元素X射线荧光光谱分析及其应用

采用X射线荧光光谱(XRF)方法研究蛛丝和蚕丝的化学元素组成,探讨成丝机制中金属离子的作用及生物丝性能优良的元素基础。XRF分析蚕丝中C含量是47.10%、O为29.92%、N是16.52%;金属元素包括：Ca含量0.166 2%、Mg含量0.104 0%和K含量0.039 5%,而Na,Zn,Ni,Fe和Cr是微量元素。Ca和Mg元素含量高,在桑蚕吐丝机制中起着重要的作用。在蛛丝中,主要的非金属元素是：C含量44.09%、O含量26.64%和N含量22.34%。高含量的N元素可能是蛛丝优异的刚性和韧性性能的元素基础。在蛛丝中,Na含量0.268 0%、K含量0.081 4%和Mg含量0.011 6%,而Ca,Zn,Fe,Cu和Cr则是微量元素。蛛丝中Na和K元素含量高,在蜘蛛吐丝机制中可能起重要作用。运用数学统计方法研究生物丝元素组成与XRF元素分析结果吻合。     

太空诱变桔梗的X射线荧光光谱的测定分析

选用X射线荧光光谱法(XRF),对我国独创的第4代太空诱变育种桔梗、地面组桔梗和桔梗对照品的元素种类和含量进行测定与分析。结果表明,太空组桔梗中与桔梗理气、化痰功效相关的Zn,Mn,Fe等元素分别比地面组提高了1.9,2.4,0.6倍,其中Zn和Mn元素比对照品分别提高了0.6和1.9倍。即与地面组相比,太空组桔梗更趋近于或优于对照品桔梗。太空组桔梗中多种元素指标得到了大幅度的提升和优化。XRF方法具有方便快捷、灵敏度高、元素和含量范围广以及再现性好等特点,可用于一切能制成粉末样品的其他中药的测定分析。     

X射线荧光光谱法同时测定煤灰中的12种成分

采用熔融制样法,用X射线荧光光谱法同时测定煤灰中的常量、少量和微量成分SiO₂,Al₂O₃,Fe₂O₃,CaO,SO₃,TiO₂,K₂O,Na₂O,P₂O₅,Mg_O,MnO,BaO。选用混合熔剂并加入氧化剂的方式降低熔融温度,解决了硫的准确测量问题。同时通过选用土壤等标准样品解决了煤灰成分标准样品不足的问题。应用可变理论α系数及固定α系数法进行基体效应校正,所得结果与化学法的分析结果相符合。     

第4代太空防风的X射线荧光研究

利用我国发射的神舟三号飞船搭载防风种子,回收后在地面上筛选繁育,定向培育成新品种获得优良的种质资源。本文用X射线荧光光谱法（XRF）对枝叶和产量等方面占优势的第4代太空及地面组防风药用部分的元素含量进行测定和对比分析。两组样品的元素种类基本相同, 但多种矿质元素含量是太空组＞地面组。尤其是太空防风中与性味功效和归经相关的Zn,Fe,Mn和Cu含量比地面组分别提高到4.39,1.23,0.84和0.90倍。太空防风矿质元素指标明显优化。XRF方法可以从整体上对中药材的元素进行测定分析和研究。利用太空搭载防风种子可以筛选出多种元素优化的防风药材新品种。     

X射线荧光光谱压片法测定六种花瓣粉末的成分

利用X射线荧光光谱法对白玫瑰花、红玫瑰花,白康乃馨、红康乃馨,白蝴蝶兰、红蝴蝶兰3个品种6个粉末样品中元素的种类和含量进行测定,并就每组样品的测定结果进行分析比对。结果表明,3个品种的花瓣粉末中均未检测出有毒元素的存在,且花瓣粉末中元素含量丰富;除含有常量元素外,还含有如Fe,Cu,Zn,Mn,Ni,Si,Sr,Rb等多种微量元素,但3个品种的微量元素的种类及含量有所差异;同一品种的花瓣粉末中元素的种类大致相同,而元素含量却各有差异,白色比红色中元素含量高。     

X射线荧光光谱分析方法的检出限测量方法研究

X荧光光谱仪器发展迅速,应用领域广泛,由于其能够快速、准确分析样品,不需要繁琐的前处理和耗材,已能替代部分传统AAS, ICP和ICP-MS等分析仪器。如何准确地评价其应用性能,以更便捷地使用,常用检出限作为评价方法的重要指标。检出限计算方法和形式较多,一般等于空白样品的3倍标准偏差,在实际样品分析时,小于检出限的含量,不可检出;大于检出限、小于定量限的含量,可定性分析;大于定量限的含量,可准确分析。XRF计算方法和分析领域中常用的检出限计算方法不同,传统分析方法测量值符合正态分布,是连续分布;XRF测量值属于泊松分布,是离散分布,只有在计数足够大的时候才能接近正态分布。在实际分析中,往往不会耗时去积累足够大的计数。介绍了7种检出限的计算方法：X荧光泊松分布法、 K倍标准偏差法、线性校准法、 RSD法、 SD直线外推法、环境监测分析法、海洋监测规范法。以X荧光重金属检测仪的检测数据为例,测试6个大米粉参考样品中Pb, As和Cd元素含量,详细对比了各方法的计算过程和考虑因素。由于实际样品中很难找到绝对不含被测元素的空白,以近似空白样品替代。泊松分布方法测试次数最少,测2次即可快速准确计...     

阿胶真伪品的X射线荧光光谱的鉴别研究

建立了快速鉴别阿胶真伪的新方法.收集6个不同产地的阿胶样品,采用X射线荧光光谱法(XRF)测定了各样品元素种类、含量并作出了元素特征谱,与阿胶对照品的元素特征谱作对比分析.结果表明:6个样品中共有的主要元素为Ca,Na,Cl,K,Fe,Zn,Al和Mg等,但其中Cl,Ca,Na和K元素的含量却与对照品有着显著的差异,且部分特有微量元素只存在于个别样品中.依据这些不同点可以准确地对阿胶的真伪及伪劣品中有害元素的引入来源作出识别和判断.基于XRF法所作的元素特征谱可简捷快速、直观有效的鉴别阿胶真伪,有望应用于其他中药的鉴定.     

针孔相机全场X射线荧光成像的模拟研究

为解决全场X射线荧光(XRF)成像中针孔形状和尺寸的选取问题,采用Geant4软件,模拟了6种不同类型针孔和4种不同的针孔孔径,分析了这些参数对点扩散函数和调制传递函数的影响;模拟了不同能量X射线荧光平面源的成像过程,并用均值滤波和Richardson迭代法对图像进行处理,分析了图像处理的效果。模拟结果表明：对于能量小于20 keV的荧光X射线,双锥孔结合直孔模型的点扩散函数尖锐性和等晕性更好,调制传递函数的截止频率更大,空间分辨更好,更适合做全场XRF成像的针孔;均值滤波结合Richardson迭代法的图像处理算法对全场XRF图像处理的效果较好。     

超细粉末压片制样X射线荧光光谱测定碳酸岩样品中多种元素及CO_2

粉末压片X射线荧光光谱分析碳酸岩的误差主要来自粒度效应和矿物效应。为消除粒度效应影响,采用超细粉末压片制样准确测定了碳酸岩中的多种元素和CO2。使用德国FRITSCH行星式球磨机,碳化钨研磨介质将碳酸岩进行超细粉碎,为了克服团聚效应,采用了湿法研磨。随颗粒度的减小,样品表面形态更平整、光滑,康普顿散射效应减小。研究了粒度变化对各元素分析线强度的影响,通常荧光强度随粒度减小而增加。当多个组分的颗粒度减小时,S,Si,Mg的强度将增加,Ca,Al,Ti,K的强度将减小,这取决于各自的质量吸收系数。研究了粒度变化对矿物物相组成的影响。计算了各分析元素分析线的穿透厚度,当样品的粒度碎至元素分析线的穿透厚度以下时,荧光强度受粒度的影响减小。实验发现当样品碎至d95≤8μm时,基本消除了颗粒度效应影响,压片法制样,理论α系数、经验系数法结合校正基体效应,可准确测定碳酸岩样品中14个元素,方法的精密度大大改善,除Na2O外,RSD2%。C是超轻元素,荧光产额低且干扰严重。实验采用PX4人工多层膜晶体,粗准直器,X射线荧光光谱可定量测定碳酸岩中的CO2。试验发现C的测量强度随测量次数的增加而增加,且随放置时间的增加而增加(即使在干燥器中存放),因此建议使用新制的样片测定CO2。     

水汽分子对CO_2谱线加宽的影响

报道了以高分辨力连续可调谐中红外差频激光为探测光源,结合可调长光程怀特池,利用直接吸收的方法探测了CO2的10011←10002带R支以及部分P支在室温下的水汽加宽吸收光谱。在2422cm-1到2457cm-1范围内共有26条吸收谱线被探测到,采用Voigt线型对吸收谱线进行拟合,得到了CO2光谱的水汽加宽系数,结果显示CO2的水汽加宽系数平均比干燥空气的加宽系数大52%。利用实验测得的CO2的水汽加宽系数与HITRAN04数据库中CO2谱线的线位置、线强和干燥的空气加宽系数进行比较,分析了在实际大气中(海平面,10km光程)不存在水汽和存在水汽(含有2.0kPa水汽)时该波段CO2的大气透过率,结果表明潮湿空气与干燥空气之间的最大透过率差约为0.5‰。     

波长色散X射线荧光结合元素分析仪分析金华佛手14种元素

以VarioⅢ元素分析仪分析金华佛手C,H,O,N含量,以PW2400波长色散X射线荧光光谱仪定性扫描佛手样品,采用IQ+分析法分析Mg,Al,P,S,Cl,K,Ca,Mn,Fe,Sr元素含量。结果表明,将C,H,O,N元素含量作为固定项处理,结果较为理想;为防止样品表面脱落而采用Mylar膜将样品包裹技术,通过对膜系数的校准,分析结果比较理想。     

Qualitative and quantitative analysis of pathological and non-pathological human bone using radioisotope X-ray fluorescence technique

Pathological and non-pathological human elbow bone samples were collected from one male human patient and one female human patient who were undergoing treatment in our University Research Hospital. Pathological and non-pathological human elbow bone samples were analyzed by means of energy-dispersive X-ray fluorescence spectrometry by using standard additions method. Experimental results are presented and discussed in this work.     

Evaluation of the dose received in the tissues of the neck during quantification of iodine in the thyroid by X-ray fluorescence spectrometry

The determination of the iodine content in the thyroid is of great interest for many investigations of this gland. The conventional scintigraphic method, using radionuclides, is efficient but delivers a significant dose to the patient. The X-ray fluorescence spectrometry could give information about the iodine content in the thyroid. The measured signal is obtained after stimulation of the stable iodine contained in the gland by X-rays. The advantage of this technique is the complete absence of radioactive isotope injected into the patient body. By applying this, a decrease in effective dose to the patient should be obtained. In this work, the study of the dose received by a thyroid phantom (surrounded by the different tissues of the neck) was performed. The phantom is made of PLA. The dose is measured in optimised conditions defined for the analytical technique. A total head-neck phantom was also used in order to consider the absorbed dose in each different tissues and organs as spinal cord or eyes. Thermo-luminescence dosimeters were chosen for their small size, their sensitivity and the easy positioning on the surface of the phantom but also inside of it to evaluate dose to internal organs. Those LiF 100 dosimeters have been calibrated within the X-ray beam also used for the analysis of iodine. The repeatability and reproducibility of the method has been evaluated. The influence of parameters as concentration of iodine in the thyroid, distance between the X-ray generator and the neck, thickness of the tissues surrounding the thyroid, has been investigated in terms of modifying parameters of the dose received by different tissues situated in the neck and the head.     

内标法在土壤重金属镍元素X荧光分析中的应用研究

利用能量色散型XRF重金属实验平台,在实验室自然大气环境下获取土壤的X射线荧光,通过X射线荧光光谱法定量分析了国家标准土壤样品中元素Ni的含量。实验研究了土壤中Ni元素的X荧光特征分析谱线,采用加入内标法测定了Ni元素定标曲线,并依据实验结果分析了内标元素选取方法。实验结果表明,对土壤样品进行内标法分析时,可选取基体中适宜元素作为内标元素;使用Pb的Lα线,Cu和Fe的Kα线作内标线时相对标准偏差(RSD)分别为6.24%,5.24%和5.22%,说明选择合适基体主量元素的特征谱线作为内标线,可有效提高测量结果的准确性。     

Application of X-ray fluorescence spectrometry in plant science: Solutions,threats, and opportunities

X-ray fluorescence (XRF) spectrometry is a nondestructive, rapid, simultaneous multi-elemental imaging methodology for plant materials. Its applications are broad and cover most of the elements with varying concentration below the parts per million (ppm). XRF is a well-established atomic spectrometric technique that is also being used as a field portable instrumentation. In recent decades, XRF has been considered a very versatile tool for plant nutrition diagnosis due to its fast and multi-elemental analytical imaging response directly from a solid sample. In this review, we have mainly focused on the recent developments and advancements in XRF spectrometry to analyze plant materials. We have also included the fundamental aspects and instrumentation for XRF spectrometry for its use in plants imaging. We have also covered the use of XRF for vegetal tissues and plant leaves. Mainly, we have briefly focused on some features of sampling procedures and calibration strategies regarding the use of XRF for plant tissues. Microchemical imaging applications by XRF, μ-XRF, μ-SRXRF, and TXRF have been covered for a wide variety of plant tissues such as leaves, roots, stems, and seeds.     

Quantification via X-ray fluorescence analysis of oxygen in the surface layer of a Si-sphere used as a new mass standard

The distribution of oxygen present in the surface layer of the Si-sphere used as new mass standard is measured and quantified using the combined X-ray fluorescence (XRF)/X-ray photoelectron spectroscopy (XPS) surface analysis system in the Center for Measurement Standards, Industrial Technology Research Institute (CMS/ITRI). A radiometric calibration of the X-ray source is not possible because the spectral distribution of the X-ray tube used is complex and not stable over the long term. Hence, the quantification of oxygen on the Si-sphere is based on a calibration curve that establishes a correlation between the mass deposition of oxygen from the calibration samples qualified by PTB and the ratio of the oxygen fluorescence to silicon RRS (resonant Raman scattering) intensities in the in-house system. This paper presents the methodology for and the results of an oxygen quantification performed using the combined XRF/XPS surface analysis system. With a relative uncertainty of less than 10%, the average mass deposition of oxygen on the Si-sphere was 133 ± 12 ng/cm². The oxygen quantified via XRF is treated as a reference for the quantification of other elements on the surface layer. The quantification of carbon mass deposition in the surface layer in relation to the oxygen mass deposition is also described in this paper. The surface analysis system is part of our contribution to the realization and dissemination of the unit of the kilogram (based on its new definition) via the XRCD method.     

Phase transition and chemical decomposition of liquid carbon dioxide and nitrogen mixture under extreme conditions

Thermodynamic and chemical properties of liquid carbon dioxide and nitrogen(CO_(2~–)N_2) mixture under the conditions of extremely high densities and temperatures are studied by using quantum molecular dynamic(QMD) simulations based on density functional theory including dispersion corrections(DFT-D). We present equilibrium properties of liquid mixture for 112 separate density and temperature points, by selecting densities ranging from ρ = 1.80 g/cm~3 to 3.40 g/cm~3 and temperatures from T = 500 K to 8000 K. In the range of our study, the liquid CO_(2~–)N_2 mixture undergoes a continuous transition from molecular to atomic fluid state and liquid polymerization inferred from pair correlation functions(PCFs)and the distribution of various molecular components. The insulator–metal transition is demonstrated by means of the electronic density of states(DOS).