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%。     

电化学谱学表征方法的应用与发展

经历两个多世纪的发展,电化学表征方法的理论和实验研究不断完善,在表界面精细结构表征、电化学反应机理研究等方面起到重要作用。电化学谱学表征技术的出现,填补了传统电化学表征方法在分子水平上鉴定电化学反应活性位点及中间物种的空白。本文总结了近年来红外光谱(IR)、表面增强拉曼光谱(SERS)及和频振动光谱(SFG)三种经典分子振动光谱电化学表征技术的研究进展。首先介绍了三种光谱的基本原理和电化学联用电解池的设计,然后从基础电化学理论出发,介绍其在模型单晶体系及界面水机理研究中的应用,进一步重点介绍了其在锂离子电池和燃料电池领域的相关研究进展,最后展望了电化学谱学表征技术的未来发展方向。     

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。     

基于加权相位分离的二维互相关弹性成像方法研究

弹性成像能够检测组织的弹性信息,进而描述组织生理、病理状态,对疾病的检测和诊断具有重要的应用价值。为了改善二维弹性算法的轴向分辨率,本文对一维和二维弹性成像算法进行了比较研究,提出一种基于加权相位分离和二维互相关的混合位移估计算法,首先利用二维时域互相关技术进行粗估计,然后再利用加权相位分离技术(WPS)对结果进行精估计。同时,通过仿真和仿体实验对算法的精确性和效率进行了验证。结果表明,算法具有较好的鲁棒性,能够有效地提高运行效率和图像信噪比,上述研究对高性能弹性成像系统的研究与设计具有重要的指导意义。     

基于内扩散有效因子测定实验的3D虚拟仿真实验预习系统设计

催化剂内扩散有效因子测定实验是大学基础实验之一,传统的实验预习方法注重理论介绍,不能给学生以直观的感受和操作体验,导致学生对实验设备、操作步骤比较陌生。针对此问题,设计出一种基于3D虚拟仿真技术的实验预习系统,用操作3D虚拟仿真实验模型的方式来提高学生的实验预习效果。此系统还能基于一种惩罚扣分评分模型进行考核,能够对操作数据进行统计分析,不仅帮助学生加深对实验的理解,而且有利于提高教学质量。     

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.     

基于气液相化学发光技术的臭氧在线检测方法

基于鲁米诺(luminol) 化学发光体系,采用自主研发的在线臭氧浓度检测仪,建立了一种实时在线检测臭氧浓度的方法,用于分析测定痕量浓度水平的臭氧气体。 考察了鲁米诺、氢氧化钾、部分醇类化合物和表面活性剂等因素对化学发光强度的影响。 结果表明,在鲁米诺(0.005 mol/L)、氢氧化钾(0.05 mol/L)体系中加入乙二醇(体积分数1.5%)、甲醇(体积分数1.5%)、乙醇(体积分数1.0%)、丙三醇(体积分数3.0%)能显著增强鲁米诺体系检测O₃的化学发光信号,而甲醛溶液 (体积分数3.0%)能有效抑制NO₂信号的干扰。 同时,测得检测臭氧的检出限为1.26 μg/m³、相对标准偏差为0.32%,相对误差为0.75%。 利用该体系测定臭氧,具有信号稳定、精密度好、准确度高、检出限低等优点,适用于大气中微量O₃的在线连续检测。     

基于PLA的形状记忆聚酯嵌段聚氨酯的相分离行为

以2,4-甲苯二异氰酸酯(TDI)为封端剂,乙二醇(EG)为扩链剂通过2步法合成了一系列具有不同聚丙交酯(PLA)分子量和不同TDI-EG链段长度的聚丙交酯嵌段聚氨酯(PLA-PU)。其中,PLA的分子量从1 500到9 500,PLA、TDI和EG的摩尔比从1:2:1至l:7:6。通过DSC和WAXD等测试技术对材料的两相分离程度进行了研究。结果发现,PLA-PU的相分离程度与样品的热历史具有密切的关系,样品中PLA的分子量和TDI-EG长度对于材料的相分离速率和相分离结构的完善程度具有较大的影响。     

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.     

A Method of Orthogonal Oligosaccharide Synthesis Leading to a Combinatorial Library Based on Stationary Solid‐Phase Reaction

A new, efficient synthesis of oligosaccharides, which involves solid‐phase reactions without mixing in combination with an orthogonal‐glycosylation strategy, is described. Despite a great deal of biological interest, the combinatorial chemistry of oligosaccharides is an extremely difficult subject. The problems include 1) lengthy synthetic protocols required for the synthesis and 2) the variety of glycosylation conditions necessary for individual reactions. These issues were addressed and solved by using the orthogonal‐coupling protocol and the application of a temperature gradient to provide appropriate conditions for individual reactions. Furthermore, we succeeded in carrying out solid‐phase reactions with neither mechanical mixing nor flow. In this report, the synthesis of a series of trisaccharides, namely, α/β‐L ‐Fuc‐(1→6)‐α/β‐D ‐Gal‐(1→2/3/4/6)‐α/β‐D ‐Glc‐octyl, is reported to demonstrate the eligibility of the synthetic method in combinatorial chemistry.     

Enantiomer Separation of α—Dimethyl Dicarboxylate Biphenyl and Related Biphenyl Compounds by Normal Phase HPLC on Polysaccharide Based Chiral Stationary Phases

Cellulose tris(4-methylphenylcarbamate),amylose tris(3,5-dimethylphenylcarbamate) and amylose tris (phenylcarbamate) were prepared by the method reported by Okamoto and were coated onto an aminopropylated mesoporous spherical silica gel.These final products were used as chiral stationary phases of high performance liquid chromatography for the eighteen structurally related biphenyl compounds.The resolution was made using normal-phase methodology with a mobile phase consisting of n-hexane-alcohol(ethanol,1-propanol,2-propanol or 1-butanol).The effects of various aliphatic alcohols in the mobile phase were studied.The structural features of the solutes that influence their k′ were discussed.A dominant effects of trifluoroacetic acid on chiral separation of acidic solutes was noted.