Determination of the Biodiesel Content in Diesel/Biodiesel Blends: A Method Based on Fluorescence Spectroscopy

Blends of biodiesel and diesel are being used increasingly worldwide because of environmental, economic, and social considerations. Several countries use biodiesel blends with different blending limits. Therefore, it is necessary to develop or improve methods to quantify the biodiesel level in a diesel/biodiesel blend, to ensure compliance with legislation. The optical technique based on the absorption of light in the mid-infrared has been successful for this application. However, this method presents some challenges that must be overcome. In this paper, we propose a novel method, based on fluorescence spectroscopy, to determine the biodiesel content in the diesel/biodiesel blend, which allows in loco measurements by using portable systems. The results showed that this method is both practical and more sensitive than the standard optical method.     

拉曼光谱中荧光抑制技术的研究新进展综述

拉曼光谱技术反映了物质的结构特征,可用于分析有机或者无机样品的化学组分。但由于某些被测物的荧光背景远远强于拉曼信号,这些物质的拉曼光谱测量有时十分困难,这限制了拉曼光谱的广泛应用。因此有必要在拉曼检测中对荧光采取抑制措施以准确获取高信噪比的拉曼光谱指纹信息。近些年来,很多的相关研究探讨及发展了多种荧光抑制的新方法。在目前的科研活动中,常用的技术有表面增强拉曼光谱技术、傅里叶变换拉曼光谱技术、共焦显微拉曼光谱技术和高温拉曼光谱技术等。这些技术解决了拉曼光谱早期存在的一些问题,如荧光干扰、灵敏度低等,极大地扩展了拉曼光谱技术在各个领域的应用。而这些新方法可大致归类为物理/化学方法,基于光学性质不同衍生的方法,计算处理方法和其他方法。文章概括性的介绍了上述方法的理论、实现方式,并分析比较了各自的特点。     

Characterization of Monoolein-Based Lipoplexes Using Fluorescence Spectroscopy

Lipoplexes are commonly used as delivery systems in vitro and in vivo, the role of a neutral lipid as helper being of extreme importance in these systems. Cationic liposomes composed of dioctadecyldimethylammonium bromide (DODAB) with monoolein (MO) as a helper, at different molar ratios (1:2; 1:1 and 1:0.5) were prepared, and subsequently titrated to DNA. The structural and physicochemical properties of the lipid/DNA complexes were assessed by ethidium bromide (EtBr) exclusion, 90° static light scattering (90° SLS) assays and fluorescence resonance energy transfer (FRET). In EtBr exclusion assays, the steady-state fluorescence spectra of EtBr were decomposed into the sum of two lognormal emissions, emanating from two different environments – H₂O and DNA, and the effect of charge ratio (+/-) was observed. 90° SLS assays gave an important contribution, detecting size variations in systems with different MO fractions on the lipoplexes. In FRET assays, 2-(3-(diphenylhexatrienyl)propanoyl)-1-hexadecanoyl-sn-glycero-3-phosphocholine (DPH-HPC) was used as donor and EtBr as acceptor. The DNA component previously calculated by EtBr exclusion, was used to determine the energy transfer efficiency, as an indirect measurement of the lipoplexes structural and physicochemical properties. Our results demonstrate that the inclusion of monoolein in the cationic liposomes formulation significantly modifies the rate of DNA complexation, being DODAB:MO (1:1) the system with higher DNA condensation efficiency.     

Study of Organized Media Using Time-Resolved Fluorescence Spectroscopy

Many photophysical processes which occur on an ultrafast time scale in ordinary liquids become significantly retarded in organized assemblies, by two to three orders of magnitude. Recently many groups have applied ultrafast laser spectroscopy and theoretical methods to elucidate this dramatic phenomenon. Although the implications of this phenomenon in biology and chemistry are not yet fully understood, it has been demonstrated that ultrafast time-resolved fluorescence spectroscopy is a very powerful tool to study the microscopic properties of the organized assemblies and that water or other liquids confined inside these assemblies are fundamentally different from the corresponding liquid in bulk.     

土壤重金属铅元素的X射线荧光光谱测量分析

在实验室条件下,利用NITON XLt793型便携式X射线荧光光谱重金属分析仪测量并分析土壤中铅元素的X射线荧光光谱特性。分别以铅的L_α(10.55 keV)和L_β(12.61 keV)特征谱线作为分析线,分析了不同基体元素对分析线的影响;测定在不同铅浓度下的特征谱线强度变化。结果表明铅的质量分数在10×10-6～1 800×10-6范围内,元素的光谱强度与浓度之间呈现较好的线性关系;建立了铅元素的定标曲线,并计算得到铅的检出限为7.89×10-6。     

Spectroscopic Application of Realgar Using X-ray Fluorescence and Raman Spectroscopy

ABSTRACT

Samples of realgar ore were collected from the hydrothermal products of the Eocene volcanic material of the Erzurum region in Turkey. The prepared samples were analyzed by polarized energy dispersive X-ray fluorescence (PEDXRF) and by confocal Raman spectroscopy (CRS). The goal of this study was to figure out the chemical composition of realgar and its properties through PEDXRF and CRS and the optical characteristic features under the polarized microscope. The result of the XRF analysis shows the collected realgar samples are mainly composed of As, S, Si, and Mg in different proportions. The contents of As in realgar change from 36.55% through 31.49% to 5.97% in the analyzed samples. The strong peak of the realgar samples is at 352 cm^?1, and a weaker peak exists around 190 cm^?1. The accuracy and precision of the technique for chemical analysis is demonstrated by analyzing CRM 2126-81. The realgar ores were studied by use of CRS and polarized microscopy.     

基于三维荧光光谱技术的食用油快速分析研究

利用F7000荧光分光光度计测得橄榄油等几种食用油及其煎炸油的三维荧光光谱,并用提高峰值阈值等算法进行分析.分析发现:不同品种食用油的三维荧光等高线图差异明显,具有指纹特征性;同一种食用油经过不同时间高温加热后的三维荧光光谱存在荧光等高圈中心波长红移、峰值强度减弱趋势.利用吸收光谱法测得同一种油加热不同时长油样的透射光谱并进行比对,发现差异性不明显.实验表明:食用油的三维荧光光谱指纹特征可用于食用油品种的鉴定,根据其荧光峰值强度大小、中心波长位置可以实现食用油品质的定性分析.     

近红外激发荧光光谱与拉曼光谱快速鉴别马铃薯品种

马铃薯是世界上最重要的食物之一,快速无损的进行马铃薯品种鉴别对其在应用中更好的发挥品种优势具有重要作用。研究了以近红外荧光光谱和近红外拉曼光谱的土豆品种鉴别,并对两者进行了比较。实验采用3个品种共98个土豆样本,随机将其分成校正集(74个)和预测集(24个)。首先使用785nm近红外激光激发,采集所有样本的荧光和拉曼混合光谱,然后从混合光谱中分别提取荧光光谱和拉曼光谱,最后对荧光光谱和拉曼光谱进行偏最小二乘判别分析(PLS-DA),PLS-DA模型采用留一法和全交互验证。结果显示,荧光光谱与拉曼光谱都能够对三个马铃薯品种进行鉴别,其中荧光光谱的PLS-DA模型预测Favorita品种效果较好(灵敏度为1,特异性0.86,准确性0.92),但Diamant品种(灵敏度为0.75,特异性0.75,准确性0.75)和Granola品种(灵敏度为0.16,特异性0.89,准确性0.71)预测的效果较差,而拉曼光谱图很好的解释了马铃薯中的主要营养成分,基于拉曼光谱的PLSDA模型的预测效果(三个品种预测灵敏度,特异性,准确性均为1)比荧光光谱判别效果显著提高。     

Electron-Impact Fragmentographic Fluorescence Spectroscopy of Ethanol,Acetaldehyde, 1- and 2-Propanol and Acetone

Abstract

Gaseous ethanol, acetaldehyde, 1-propanol, 2-propanol and acetone at pressures of 2 × 10^?5 to 5 × 10^?4 torr were irradiated with electrons of energies 0-1000 eV. The visible-region fluorescence of the excited fragments was then measured. Studies included pressure dependence, electron energy dependence, threshold energy measurements, and excitation curve measurements. The aim of the research was to ascertain if molecules of similar structure could be differentiated by their spectra.     

Fluorescence Quantum Yield Determination of Propylparaben Using Flow Injection Spectroscopy

The determination of the fluorescence quantum yield of Propylparaben is introduced and applied to L-tyrosine as a standard by a new approach that can be applied to the pharmaceutical compound utilised in this study. The quantum yield is a critical figure of quality for the optical nature of a fluorophore. Numerous investigations have considered the glitter in both pharmaceutical and nature compounds for its medical and industrial significance. A straightforward method is detailed here to decide the quantum yield of Propylparaben in solution as an element of the fluorescence concentration. For this reason, L-Tyrosine is chosen as a fluorescence standard perspective to gauge the Propylparaben fluorescence quantum yield. The impacts of pH, solvents and flow rate on the assessment of quantum yield and quantum efficiency, for the reference and the solutions of Propylparaben, have been investigated. The results indicated that these parameters significantly influence the accuracy of the method. Diverse methods are concentrated on to represent distinctive quantum yield advancements with the quantum efficiency. The impact of these parameters was likewise considered. In this study, the application of the single method may be taken into consideration to compute quantum yield of Propylparaben, which was 0.36, and this is an exceptionally basic and general technique to solve the imperative issue of luminescence quantum yield assurance of other fluorescence compounds.     

基于激光诱导时间分辨荧光的原油识别方法研究

在柴油、汽油、重质燃料油等成品油和原油等溢油油源的区分方面,荧光光谱结合模式识别手段得到了广泛的应用。传统的三维荧光光谱分析方法虽然能够获得溢油样品丰富的成分信息,但难以适应现场应用的要求,目前还停留在实验室检测的阶段。发展适用于现场应用的原油识别方法,对于海洋溢油污染的快速响应与处理意义重大。面向激光雷达的需要,发展了一种基于激光诱导时间分辨荧光手段、结合支持向量机（SVM）模型的原油识别方法,从时间和波长两个不同维度出发,通过对时间窗口和波长范围的选取进行优化,获得了理想的油种识别准确率。实验结果表明通过选取ICCD探测延时为54～74 ns可以将分类正确率从全谱线数据的83.3%提高到88.1%。通过选取波长范围为387.00～608.87 nm的谱线数据,可将疑似油种的分类正确率从全谱线数据的84%提高到100%。激光荧光雷达在实际工作中,受波浪、运载平台晃动等因素的影响,探测延时会出现一定的波动。本文介绍的分类识别方法通过时间和波长两个维度的筛选,更加适用于现场探测数据的识别,并进一步凸显了原油时间分辨荧光光谱特征,为疑似油种分类识别过程中数据量的压缩提供了重要依据。     

Multi-Photon Fluorescence Correlation Spectroscopy: a Quantification of Tryptophan Methylester Solutions by Visible Emission

A multi-photon excitation fluorescence correlation system has been developed. The emission from tryptophan methylester solution was observed by this system and analyzed by the intensity correlation function of the visible emission, which originates from the two-photon excitation of photo products generated through a five-photon process. The intensity and the product concentration were proportional to the concentration of tryptophan methylester at a lower concentration range and thus the generation process is a single molecular reaction. The correlation analysis determined the concentration of tryptophan methylester down to 5 μM. The photo product generation from tryptophan solution was enhanced by a potassium iodide addition. These results suggest a new quantification method of tryptophan derivatives.     

利用同步荧光光谱快速鉴别潲水油

为快速鉴别潲水油,采用三维同步荧光光谱结合平行因子法解析潲水油的特征波长差(Δλ),并利用支持向量机建立潲水油鉴别模型。结果表明,潲水油的特征Δλ为60 nm;特征Δλ下的样品原始同步荧光光谱经过主成分分析提取5个主成分,以径向基函数(RBF)为核函数,利用网格搜索和6-fold交叉验证优化建模参数,得到惩罚因子C=512、核参数g=0.5,该条件下建立的模型对训练集和预测集的判别率均达到100%。采用同步荧光光谱可以快速、准确地鉴别潲水油。     

Detection and Evaluation of Normal and Malignant Cells Using Laser-Induced Fluorescence Spectroscopy

The aim of this research is to study the normalized fluorescence spectra (intensity variations and area under the fluorescence signal), relative quantum yield, extinction coefficient and intracellular properties of normal and malignant human bone cells. Using Laser-Induced Fluorescence Spectroscopy (LIFS) upon excitation of 405 nm, the comparison of emission spectra of bone cells revealed that fluorescence intensity and the area under the spectra of malignant bone cells was less than that of normal. In addition, the area ratio and shape factor were changed. We obtained two emission bands in spectra of normal cells centered at about 486 and 575 nm and for malignant cells about 482 and 586 nm respectively, which are most likely attributed to NADH and riboflavins. Using fluorescein sodium emission spectrum, the relative quantum yield of bone cells is numerically determined.     

基于拉曼光谱和多元统计分析技术的结肠癌早期诊断

为了寻找结肠癌的病理发展规律在拉曼光谱属性上的体现,采用共聚焦显微拉曼光谱仪对60例离体的正常结肠组织、腺瘤性息肉和腺癌组织的近红外拉曼光谱进行对比检测,初步探讨了三类组织的拉曼光谱特征及其改变的规律。结果表明:三类组织拉曼光谱的差异明显存在于830,855,1 032,1 210,1 323,1 335,1 445,1 450,1 655 cm^-1处,腺瘤性息肉的光谱大体位于正常组织与腺癌组织之间。以组织病理诊断为金标准,主成分分析结合线性判别分析技术建立的诊断算法区分3类组织的灵敏度分别为96.9%、85.7%和97.3%,特异性分别为82.8%、90%和92.3%。因此,拉曼光谱有潜力在分子水平上区分正常结肠组织、腺瘤性息肉和腺癌组织,有望成为结肠癌早期诊断的一种有效方法。     

355 nm纳秒激光作用下荧蒽的时间分辨荧光光谱特征

多环芳烃由于具有三致(致癌、致畸、致突变)特性,其在环境中的检测受到人们广泛关注。利用时间分辨光谱技术,研究了荧蒽乙醇溶液的荧光光谱随延时时间和门宽改变的特性。研究了不同浓度荧蒽的时间分辨荧光光谱特性,以原始浓度的荧蒽为初始溶液,通过逐级稀释的方式,最终将原始溶液稀释16倍,拟合了不同稀释倍数下的荧蒽荧光强度衰减随延时时间变化的动力学曲线,得到了不同浓度荧蒽的拟合荧光寿命。研究结果表明,荧蒽的荧光光谱特性与光谱仪探测器延时时间和门宽宽度密切相关。固定延时时间,随着光谱仪门宽宽度的变化,荧蒽的荧光强度随着门宽的增大而逐渐增强。固定门宽,改变延时时间的过程中,荧蒽的荧光强度随延时时间呈现先增大,后减小的趋势。荧蒽的荧光强度随延时时间的衰减过程符合指数衰减过程,将荧蒽乙醇溶液进行逐级稀释,荧蒽荧光强度与延时时间的衰减进行指数拟合后,得到不同稀释倍数的荧蒽乙醇溶液的衰减动力学参数,随着稀释倍数的增大,拟合得到的荧蒽荧光寿命增大。多环芳烃时间分辨光谱特征的研究,可以为环境中多环芳烃的检测提供技术基础,由于不同荧光物质具有特征的荧光寿命,因此,可以利用多环芳烃与环境中其他荧光物质的不同荧光寿命特性,准确识别环境中的多环芳烃污染物。     

Quantification of Hydroxyacetaldehyde in a Biomass Pyrolysis Liquid Using 13C NMR Spectroscopy

We report on a method that allows direct identification and quantitative determination of hydroxyacetaldehyde using ¹³C NMR spectroscopy. The quantitative procedure was checked and validated with commercially available hydroxyacetaldehyde and then applied to the carbohydrate fraction of a biomass pyrolysis liquid (bio‐oil).     

荧光光谱法研究抗癌药物与DNA的相互作用

荧光探针技术可以用来测定药物-核酸相互作用的强度。通过药物与核酸相互作用,使DNA与探针键合的程度减小,反映在探针荧光光谱的改变,从而可以了解药物和核酸的作用机理。相互作用常数D为DNA 探针中加入药物后探针的荧光强度相对于DNA 探针荧光强度减去纯探针荧光强度的下降百分数。文章利用盐酸小檗碱(Berberine)作为探针,测定几种抗癌药物加入DNA与荧光探针(盐酸小檗碱)混合溶液的荧光谱,探讨它们与DNA的相互作用。并根据相同浓度的不同药物与核酸相互作用的常数D确定作用强弱。     

基于近红外漫反射光谱的农田原位表层土壤含水量定量建模方法比较

在农田尺度下,土壤表层因理化性状、粗糙度、作物根系和秸秆残茬等引起的空间异质性较为明显,样点间含水量差别相对较小,这对基于近红外漫反射光谱技术的表层土壤含水量原位测定带来极大的挑战。本研究分别利用基于单一波长(1 200,1 400,1 450,1 820,1 940,2 000和2 250 nm)反射率构建的指数衰减模型、基于归一化土壤湿度指数(NSMI)和相对吸收深度(RAD)构建的线性模型、基于土壤含水量高斯模型(SMGM)所得的拐点宽度(σ)、函数中心振幅(R_d)和高斯曲线面积(A)三个参数构建的线性或二次模型,以及基于波长区间反射率构建的偏最小二乘模型(PLS),对土壤体积含水量(VMC)进行定量分析。结果表明：(1)在单一波长反射率构建的所有指数衰减模型中,2 000 nm波长显示出最佳验证效果,RMSEp最低(2.463),RPD最大(1.06);(2)与RAD相比,NSMI的验证精度更令人满意,R2(0.312)和RPD(1.224)更高,RMSEp(2.133)更低;(3)在SMGM模型参数以及PLS模型拟合VMC的验证结果中,R_d具有最佳拟合精度,其R2(0.253)和RPD(1.175)最高,RMSEp(2.222)最低;(4)总的来看,NSMI指标构建的线性模型是所有方法中精度最高的,而且计算过程简单,易于操作,可作为表层土壤含水量原位测定的首选方法。