基于波数校准下傅里叶红外气体分析仪模型传递的研究

傅里叶变换红外光谱仪具有扫描速度快、分辨率高、波数精度高、灵敏度高和光谱范围宽等优点,因而应用于各个领域.但在实际应用中,由于仪器间的差异、仪器自身随时间的变化或者样品特性等问题,导致在一台仪器上建立的校正模型不能推广至其他仪器长期使用,使得傅里叶变换红外光谱法(FTIR)的应用受到了校正模型的限制,因此如何实现整机的...     

基于曲线拟合的形态相似鹅膏菌的傅里叶变换红外光谱研究

利用傅里叶变换红外光谱仪测试了形态相似的灰疣鹅膏菌、灰绒鹅膏菌和灰褶鹅膏菌的光谱,结果显示,它们的傅里叶变换红外光谱主要由蛋白质和多糖的振动吸收带组成,其蛋白质的吸收频率略有差。选择酰胺I带(中心频率1647cm-1)进行傅里叶自去卷积和曲线拟合处理后3种鹅膏菌中蛋白质在酰胺I带的吸收峰都由12个子峰叠加而成,其中在无序(1650cm-1)、α螺旋(1658cm-1)和β转角结构(1666cm-1)的振动吸收峰上,灰褶鹅膏菌吸收峰的面积百分比分别是20.98%、4.47%和17.14%,明显地区别于其它两种鹅膏菌(灰疣鹅膏菌:10.26%、12.58%和7.71%;灰绒鹅膏菌:14.33%、9.76%和8.83%)。在1683cm-1处的β转角吸收峰上,灰绒鹅膏菌吸收峰的面积百分比是1.92%,明显小于其它两种鹅膏菌(灰疣鹅膏菌:8.03%;灰褶鹅膏菌:6.65%)。研究表明:傅里叶变换红外光谱技术能提供大型真菌所含蛋白质二级结构信息。     

基于傅里叶成像网络的全息粒子成像技术研究

数字全息图重建可以获得物体的三维信息,在医疗、环保、化工等需要测量颗粒大小和三维信息的相关研究有着重要的科学意义和使用价值。粒子全息定位通常有计算复杂和重建精度不足等问题,为了解决相关问题,我们采用一种基于傅里叶成像网络的方法,利用傅里叶变换的特性,能够有效提取全息图的频率特征,结合深度学习技术,通过可学习的滤波器和全局感受野处理输入数据的空间频率,实现对全息图快速和准确的处理,不仅提高了数据处理效率,还具备了更强大的特征提取能力,从而实现对粒子的精确定位。本文通过实验和仿真两方面验证,并与Dense＿U＿net网络对比。结果显示,基于傅里叶成像网络的方法在定位精度和速度上都有显著的提升。并通过实验验证了该方法可行性。     

基于Unity 3D的气相色谱仪虚拟仿真实验系统的构建

虚拟仿真技术被广泛认为是一项重大技术进步,可以提供一种新颖的教学方式,能促进化学学习,打破传统教育方法的限制。三维交互式的气相色谱仪虚拟仿真实验系统使用当前主流的Unity 3D软件作为系统的主要开发工具。构建的系统主要包含仪器的动态原理展示、三维结构展示及仿真实验3部分。系统中的模型全部采用三维设计,场景逼真,能够全方位地向使用者展现真实仪器的外形及内部结构,令使用者如同置身于真实实验室中,获得身临其境的操作体验,从而更容易学习和掌握仪器组成、工作原理及相关的实验技能。系统不仅满足了仪器培训和化学实验教学的基本需求,而且对虚拟仿真技术在化学中的应用起了示范效应和推广作用。     

应用小波特征提取肺癌组织FTIR的支持向量机分类方法研究

提出了一种新的基于傅里叶变换红外光谱(Fourier Transform Infrared Spectroscopy, FTIR)的小波特征提取与支持向量机(SVM)分类方法以提高FTIR对早期肺癌的诊断准确率. 对肺正常组织、早期肺癌及进展期肺癌组织的FTIR, 利用连续小波(CW)多分辨率分析法提取9个特征量, 支持向量机把其分为正常组与非正常组(包括早期肺癌和进展期肺癌), 对正常组织、早期肺癌和进展期肺癌的识别, 多项式核函数和径向基函数的识别准确率最高. 多项式核函数对正常组织、早期肺癌和进展期肺癌的识别准确率分别为100%, 95%及100%; 径向基函数分别为100%, 95%和100%. 实验结果表明FTIR-CW-SVM模式分类方法对正常肺癌组织、早期肺癌及进展肺癌的识别具有较好的可行性.     

基于动态散斑干涉的数字全息成像技术研究

基于干涉测量原理的定量相位显微镜(QPM)在生物医学成像领域中得到了重要应用,在QPM中使用传统光源(如白光和激光)干涉的理论非常成熟。最近,在QPM中使用动态散斑照明(DSI)因其具备优于传统光源的优势而备受关注。本文基于DSI搭建了两套离轴全息成像系统(DSI-DHM),分别对USAF1951(表面镀铑高度为110 nm)标准分辨率版和人体红细胞进行了相位成像,实验结果初步验证了基于DSI数字全息系统具有高时间相干性与较低的空间相干性、高空间相位灵敏度、可扩展的视场和分辨率等优势。     

基于科学探究活动资源的化学虚拟实验系统设计研究

国内已有的化学虚拟实验系统综合性不强, 满足不了科学探究活动的设计要求。结合科学探究过程的理论基础, 设计完成了支持科学探究过程的综合性化学虚拟实验系统, 并阐述了每个模块的设计思想与过程以及其支持下的科学探究活动的实施。     

基于小波和小波包变换的苯丙酮尿症傅里叶变换衰减全反射红外光谱筛查模型的研究

应用小波和小波包变换对傅里叶变换衰减全反射红外光谱(FTIR/ATR)进行去噪处理,以提高苯丙酮尿症(PKU)筛查模型的性能。首先优化小波和小波包变换的参数,然后分别对原始光谱(OS)、9点平滑光谱(9S)和一阶微分9点平滑光谱(1D9S)进行去噪处理,以均方根误差(RMSE)、平均相对误差(MRE)、预测准确率(Acc)等为指标,考察小波和小波包变换对模型性能的影响。结果与变换前相比,模型性能均有所提高,其中小波变换以1D9S+sym12处理结果为最优,而小波包变换以1D9S+sym1为最优;Acc全部提高为100%。     

基于化学模式识别的大蒜傅里叶变换红外光谱指纹图谱多样性

以不同地理居群的大蒜为研究对象,采用傅里叶变换红外光谱法获取各样品的红外谱图及不同波数下各样品的透过率数据,运用主成分分析及聚类分析等统计学方法对谱图数据进行了比较分析。结果发现,不同地理居群大蒜的红外指纹图谱存在差异,统计学分析结果显示25个品种大致可分为4大类(其中2个样品,4号及25号与这4类间有较大差异),此现象一定程度上反映了大蒜种植地居群环境对大蒜理化性质的影响。     

多种谱学方法研究环氧乙烷/四氢呋喃共聚醚的热氧降解

采用电子自旋共振（ESR）、傅里叶变换红外光谱（FT－IR）和多种核磁共振（NMR）技术研究了环氧乙烷／四氢呋喃共聚醚的热氧降解,表 征了近20种产物结构碎片,并对EO和THF两种链节的降解作了定量讨论。共聚醚的氧化降解发生在醚键氧碳上,遵循自由基氧化机理,最后形成大量的甲酸酯、碳酸酯等酯类以及甲基、亚甲二氧基和醇,此外还检测到过氧化氢和半缩甲醛结构。分析表明共聚醚中THF链节的降解程度明显大于EO链节,而且降解容易发生在两种链节交替连接处。抗氧剂2,6－二叔丁基－4－甲基酚（BHT）不仅降低了共聚醚的氧化降解程度,还改变了降解产物的结构分布,显著抑制了碳酸酯和亚甲二氧基结构的生成,相对增加了羟基和端甲基结构。     

Infrared Chemical Sensor for Detection of Chlorinated Phenols in Aqueous Solutions Based on a ATR Waveguide Coated with Structural Designed Polymers

A combination of solid phase micro‐extraction (SPME) with attenuated total reflection (ATR) infrared spectrometry provides a fast and sensitive way to detect organic compounds in aqueous solutions. It is especially useful for detection of chlorinated organic compounds in environmental samples. Currently, analyses of organic compounds in aqueous solutions are limited to low‐polarity compounds by the SPME/ATR‐IR sensing method. This limitation was mainly caused by the low polarity nature of the SPME phase. To increase the capability of this method to detect more polar compounds and also to increase the sensitivity in detection of organic compounds, the principle of “like‐dissolve‐like” was used to design a specific SPME phase for a certain class of chlorinated compounds. To demonstrate this concept, chlorinated phenols were used as probe molecules and polyvinyl chloride was chemically modified with phenol, ‐naphthol and ‐naphthol to provide SPME phases with a similar chemical structure to chlorinated phenols. These polymers were used as SPME phases and their performance were compared with the commonly used SPME phases (i.e., polystyrene and polyisobutylene). Results indicated that naphthols attached to PVCs provided much lower compactness, which allows fast speed in absorption of phenols. Meanwhile, due to the structural similarity between naphthols attached to PVCs and phenols, much higher partition coefficients were found for these chemically modified PVCs than conventionally used polymers. To further increase the sensitivity for analysis of chlorinated phenols, the common influencing factors, such as pH values and salt effect were also investigated. Apparently, pH values of the solutions did not influence the structure of the modified PVCs significantly. In absorption of chlorinated phenols in aqueous solutions with different pH values, the observed IR signals were decreased greatly in pH higher than 6 due to the charged form of chlorinated phenols that were presented. Results of the salt effect indicated that three times stronger of IR signals can be obtained if 20% (w/vol) of NaCl was added.     

Atomic Level Characterization Based on Focus Modulation Electron Microscopy

Defocus image modulation processing and three-dimensional Fourier filtering methods are compared from the viewpoint of application to high-resolution phase transmission electron microscopy. Both methods can successfully correct the spherical aberration in TEM by image processing using through-focus images resulting in resolution improvement from the Scherzer resolution limit to the information limit. Comparing the processed images demonstrates that the potential to determine localized atomic structures between the two methods is at the same level when the sample thickness is thin. However, the achieved signal-to-noise ratio is better in images processed by the three-dimensional Fourier filtering method because the filtering process in Fourier space effectively reduces quantum noises involved in the original images. Spherical aberration-free phase observation by the latter method clearly shows the existence of individual gadolinium atoms in C₈₂ molecules encapsulated in single wall carbon nanotubes. It is demonstrated that the three-dimensional Fourier filtering method works effectively for atomic level characterization even when a sample consisting of light atoms is observed under the condition of a low electron dose.     

A Validated Chiral LC Method for the Enantiomeric Separation of Repaglinide on Amylose Based Stationary Phase

A simple, isocratic, normal phase chiral HPLC method was developed and validated for the enantiomeric separation of repaglinide, (S)-(+)-2-ethoxy-4-N [1-(2-piperidinophenyl)-3-methyl-1-butyl] aminocarbonylmethyl] benzoic acid, an antidiabetic in bulk drug substance. The enantiomers of repaglinide were resolved on a ChiralPak AD-H (amylose based stationary phase) column using a mobile phase consisting of n-hexane: 2-propanol:trifluoroacetic acid (95:5:0.2 v/v/v) at a flow rate of 1.0 mL min⁻¹. The resolution between the enantiomers was found to be not >3.5 in optimized method. The presence of trifluoroacetic acid in the mobile phase played an important role, in enhancing chromatographic efficiency and resolution between the enantiomers. The developed method was extensively validated and proved to be robust. The calibration curve for (R)-enantiomer showed excellent linearity over the concentration range of 900 ng mL⁻¹ (LOQ) to 6,000 ng mL⁻¹. The limit of detection and limit of quantification for (R)-enantiomer were 300 and 900 ng mL⁻¹, respectively. The percentage recovery of the (R)-enantiomer ranged between 98.3 and 101.05% in bulk drug samples of repaglinide. Repaglinide sample solution and mobile phase were found to be stable up to 48 h. The developed method was found to be enantioselective, accurate, precise and suitable for quantitative determination of (R)-enantiomer in bulk drug substance.