自适应拉曼光谱成像数据去噪及其在植物细胞壁光谱分析中的应用

拉曼光谱成像数据存在基线漂移与宇宙射线干扰峰两类噪声信号,无法直接用于光谱分析研究,必须去除。现有单光谱去噪方法处理结果不稳定、可重复性差。针对这一问题,本研究提出了一种自适应拉曼光谱成像数据新型去噪法,采用优化的自适应迭代惩罚最小二乘法( Adaptive iteratively reweighted penalized least-squares,airPLS)和基于主成分分析( PCA)的干扰峰消除算法修正光谱基线漂移和宇宙射线干扰峰,具有输入参数少、光谱失真小、处理速度快、去噪结果稳定等优点。利用本方法去除了芒草( Miscanthus sinensis)细胞壁拉曼光谱成像数据(9010条光谱)中的噪声信号,并对去噪后数据进行PCA和聚类分析(CA),成功区分非植物光谱与植物光谱,分类结果优于未去噪数据。预期本方法可应用于其它光谱成像数据去噪,为光谱的解译和定量分析提供可靠的研究基础。     

基于拉曼光谱技术的联苯苄唑药物有效成分的快速鉴定和生产溯源研究

有效成分的定性和定量分析是药物分析的核心。实际样品测定中,通常需要进行样品前处理,以消除复杂辅料成分的干扰,此过程耗时长,且难度较大。因此,发展快速定性筛查技术,提高药物分析的工作效率非常必要。本研究以联苯苄唑药品作为模型药物,将拉曼光谱技术和主成分分析(Principal components analysis, PCA)和支持向量机(Support vector machine, SVM)等机器学习算法联用,探讨了其用于药物有效成分快速定性分析的可行性。针对不同药品中辅料成分复杂、组成不一,并且其拉曼光谱谱图与低含量(1%)的联苯苄唑分子的谱图存在明显交叠的问题,以原料药的拉曼光谱为基准,利用PCA方法精准定位和提取成品药拉曼谱图中联苯苄唑分子的特征拉曼光谱信息,实现了准确定性分析。本研究无需获得每一种辅料的特征拉曼光谱谱图,根据拉曼谱图中1600和1650 cm^-1等处谱峰的细微差异,采用PCA方法结合SVM分类器策略,实现了药物生产溯源的准确区分和鉴定。本研究为药物分析研究提供了一种无损快速溯源的分析方法。     

拉曼光谱技术结合主成分分析-支持向量机对砷类矿物药的分类识别研究

为了快速检测砷类矿物药,建立了拉曼光谱技术结合主成分分析(PCA)-支持向量机(SVM)分类识别砷类矿物药的新方法.首先对雄黄、雌黄、信石和砒霜的拉曼光谱进行了归属,并进行了 PCA-SVM分类识别.然后分别测定了五个批次雄黄的拉曼光谱,并进行了 PCA-SVM分类识别,最后对其拉曼光谱的差异进行了分析.该方法快速、方...     

基于显微共聚焦拉曼光谱技术快速检测3种梭菌中肉毒梭菌

提出了一种基于显微共聚焦拉曼光谱技术的肉毒梭菌快速鉴别方法.利用共聚焦显微拉曼光谱技术(CRM)采集了肉毒梭菌、艰难梭菌和产气荚膜梭菌的拉曼光谱,比较了3种梭菌的平均拉曼光谱,采用基线校正、标准正态变换、Savitzky-Golay 5点平滑和最大最小值归一化预处理后,借助主成分分析(PCA)降维并提取特征变量,对样本...     

单根(7,5)蛇形单壁碳纳米管的拉曼光谱(英文)

研究了单根(7,5)蛇形单壁碳纳米管的拉曼光谱特征,观察到了环呼吸振动峰(RBM)、环呼吸振动的倍频峰(2RBM)、介于中间频率的振动峰(IMF)、无规振动峰(D)、剪切振动峰(G)、中间频率振动峰(M)、剪切振动和环呼吸振动的和频峰(G+RBM)、面内横向光学声子和纵向声学声子的和频峰(iTOLA)、无规振动的二次共振峰(G′或者2D)以及其它一些归属不清楚的拉曼峰.不同激发波长和不同激发偏振拉曼光谱研究表明,这些拉曼光谱峰显示出了非常强的激发能量和激发偏振的选择性.     

烟煤的拉曼光谱分析

为了分析煤的化学结构及性质,本文对大同塔山矿的煤样进行拉曼光谱测试。结果表明:在拉曼光谱一级模内存在两个明显的振动峰,分别为1 367cm~(-1)的D峰与1 593cm~(-1)的G峰,通过峰强度比(I_D/I_G=0.72)和半峰宽等信息可以确定出样品中芳香层排列有序化程度较高,侧链及杂原子含量较低。除此之外,在拉曼光谱中还发现方解石、白云石、金红石、锐钛矿、磁铁矿等无机矿物质的特征峰。对煤样进行X-射线衍射(XRD)和X-射线荧光光谱(XRF)测试,在XRD光谱中发现了金红石、锐钛矿及磁铁矿的衍射峰,在XRF测试中发现Al、Si、P、S、Ca、Ti、Fe、Sr等元素类型,证实了上述矿物质的存在。     

差分拉曼光谱结合聚类分析对塑料牙刷柄的检验研究

应用差分拉曼光谱技术对39个不同品牌的塑料牙刷柄样本进行检验,得到的塑料牙刷柄差分拉曼光谱无干扰峰,只保留纯净的拉曼峰,并且其特征峰差异显著,采集其特征峰的光谱数据并将其定量化,选择离差平方和法(ward)作为其类间距离,采用平方欧氏距离作为测量区间描述样本间的亲疏程度,对定量化的光谱数据进行系统聚类分析,成功将39个...     

三(4-硝基苯基)甲烷衍生物的结构和振动光谱的理论研究（英文）

用密度泛函理论优化了三苯甲烷(1)和一系列三(4-硝基苯基)甲烷衍生物2,3和4的几何结构,并计算了其红外光谱和拉曼光谱;通过与实验光谱的对比,对实验光谱中的谱峰进行了指认,并从理论上纠正了部分对3和4红外光谱谱峰不合适的实验指认;同时预测了2,3和4的拉曼光谱.结果表明,几种化合物的振动光谱计算结果与相应的实验结果吻合良好;且化合物2,3和4的拉曼光谱具有相似性.     

表面等离激元增强金属光致发光助力表面增强拉曼光谱获取表界面分子的本征化学信息

<正>表面增强拉曼光谱(SERS)因其具有单分子的检测灵敏度和特异的分子指纹信息,在表面科学和分析检测领域得到广泛关注~1。拉曼光谱研究中除了利用谱峰频率外,还利用不同谱峰间的相对强度,以获得吸附分子的吸附构象、分子与金属界面电荷转移、材料局域化学性质等多种重要物理化学信息。然而在SERS中,贵金属纳米结构的局域表面等离激元共振(LSPR)不仅增强了样品的拉曼信号的绝对强度,也改变了SERS谱图中不同谱峰的相对强度,即不同频率的拉曼信号受到的增强作用不同,从而导致用SERS峰的相对强度所获得的样品的物理化学信息变得不可靠。虽     

拉曼光谱在石墨烯结构表征中的应用

石墨烯是sp2碳原子紧密堆积形成的二维原子晶体结构,因其独特的结构与性质引起了科学家们的广泛关注.拉曼光谱是一种快速而又简洁的表征物质结构的方法.主要综述了拉曼光谱技术在石墨烯结构表征中应用的一些最新进展.首先,在系统分析石墨烯声子色散曲线的基础上介绍了石墨烯的典型拉曼特征(G'峰、G峰和D峰),讨论了G'峰、G峰和D峰在石墨烯层数的指认和石墨烯边缘与缺陷态分析中的应用;然后,通过对石墨烯拉曼G峰和G'峰的峰位、峰型以及强度的分析,讨论了石墨烯的层间堆垛方式、掺杂、基底、温度和应力等对石墨烯的电子能带结构的影响;最后,介绍了石墨烯中的二阶和频与倍频拉曼特征以及石墨烯的低频拉曼特征(剪切和层间呼吸振动模),并讨论了其对石墨烯结构的依赖性.     

Trichomonads under Microscopy.

Trichomonads are flagellate protists, and among them Trichomonas vaginalis and Tritrichomonas foetus are the most studied because they are parasites of the urogenital tract of humans and cattle, respectively. Microscopy provides new insights into the cell biology and morphology of these parasites, and thus allows better understanding of the main aspects of their physiology. Here, we review the ultrastructure of T. foetus and T. vaginalis, stressing the participation of the axostyle in the process of cell division and showing that the pseudocyst may be a new form in the trichomonad cell cycle and not simply a degenerative form. Other organelles, such as the Golgi and hydrogenosomes, are also reviewed. The virus present in trichomonads is discussed.     

Raman spectroscopy based analysis of milk using random forest classification

The development of a classification system based on the Raman spectra of milk samples is proposed in present study. Such development could be useful for nutritionists in suggesting healthy food to infants for their proper growth. Previously, molecular structures in milk samples have been exploited by Raman spectroscopy. In the current study, Raman spectral data of milk samples of different species is utilized for multi-class classification using a dimensionality reduction technique in combination with random forest (RF) classifier. Quantitative and experimental analysis is based on locally collected milk samples of different species including cow, buffalo, goat and human. This classification is based on the variations (different concentrations of the components present in milk such as proteins, milk fats, lactose etc.) in the intensities of Raman peaks of milk samples. Principal component analysis (PCA) is used as a dimensionality reduction technique in combination with RF to highlight the variations which can differentiate the Raman spectra of milk samples from different species. The proposed technique has demonstrated sufficient potential to be used for differentiation between milk samples of different species as the average accuracy of about 93.7%, precision of about 94%, specificity of about 97% and sensitivity of about 93% has been achieved.     

Characterization of Mononuclear Non‐heme Iron(III)‐Superoxo Complex with a Five‐Azole Ligand Set

Reaction of O₂ with a high‐spin mononuclear iron(II) complex supported by a five‐azole donor set yields the corresponding mononuclear non‐heme iron(III)–superoxo species, which was characterized by UV/Vis spectroscopy and resonance Raman spectroscopy. ¹H NMR analysis reveals diamagnetic nature of the superoxo complex arising from antiferromagnetic coupling between the spins on the low‐spin iron(III) and superoxide. This superoxo species reacts with H‐atom donating reagents to give a low‐spin iron(III)–hydroperoxo species showing characteristic UV/Vis, resonance Raman, and EPR spectra.     

Molecular Targets Implicated in the Antiparasitic and Anti-Inflammatory Activity of the Phytochemical Curcumin in Trichomoniasis

Trichomoniasis, is the most prevalent non-viral sexually transmitted disease worldwide. Although metronidazole (MDZ) is the recommended treatment, several strains of the parasite are resistant to MDZ, and new treatments are required. Curcumin (CUR) is a polyphenol with anti-inflammatory, antioxidant and antiparasitic properties. In this study, we evaluated the effects of CUR on two biochemical targets: on proteolytic activity and hydrogenosomal metabolism in Trichomonas vaginalis. We also investigated the role of CUR on pro-inflammatory responses induced in RAW 264.7 phagocytic cells by parasite proteinases on pro-inflammatory mediators such as the nitric oxide (NO), tumor necrosis factor α (TNFα), interleukin-1beta (IL-1β), chaperone heat shock protein 70 (Hsp70) and glucocorticoid receptor (mGR). CUR inhibited the growth of T. vaginalis trophozoites, with an IC₅₀ value between 117 ± 7 μM and 173 ± 15 μM, depending on the culture phase. CUR increased pyruvate:ferredoxin oxidoreductase (PfoD), hydrogenosomal enzyme expression and inhibited the proteolytic activity of parasite proteinases. CUR also inhibited NO production and decreased the expression of pro-inflammatory mediators in macrophages. The findings demonstrate the potential usefulness of CUR as an antiparasitic and anti-inflammatory treatment for trichomoniasis. It could be used to control the disease and mitigate the associated immunopathogenic effects.     

Raman spectroscopic identification of single bacterial cells at different stages of their lifecycle

Early, rapid, and reliable bacterial identification is of great importance in natural environments and in medical situations. Numerous studies have shown that Raman spectroscopy can be used to differentiate between different bacteria under controlled laboratory conditions. However, individual bacteria within a population exhibit macromolecular and metabolic heterogeneity over their lifetime. Therefore it is important to be able to identify and classify specific bacteria at different time points of the growth cycle. In this study, four species of bacteria were used to explore the capability of confocal Raman spectroscopy as a tool for the identification of (and discrimination between) diverse bacterial species at various growth time points. The results show that bacterial cells from different growth time points (as well as from a random growth phase) can be discriminated among the four species using principal component analysis (PCA). The results also show that bacteria selected from different growth phases can be classified with the help of a prediction model based on principal component and linear discriminant analysis (PC-LDA). These findings demonstrate that Raman spectroscopy with the application of a PC-LDA model rooted in chemotaxonomic analysis has potential for rapid sensing of microbial cells in environmental and clinical studies.     

Discrimination of Human and Nonhuman Blood by Raman Spectroscopy and Partial Least Squares Discriminant Analysis

A novel method is reported to discriminate human and animal blood by Raman spectroscopy without complex sample preparation. A partial least squares discriminant analysis model was constructed from a calibration set of Raman spectra from three species of animal blood using 785-nm laser excitation. The discrimination between human and nonhuman blood was calculated by three sigma. Various performance measures, including a blind test and external validation, confirmed the discriminatory performance of the chemometric model. The model provided 100% accuracy in its differentiation between human and nonhuman blood. These results demonstrate that Raman spectroscopy is a promising tool for the discrimination of animal and human blood.     

Discrimination of natural gas-related bacteria by means of micro-Raman spectroscopy

Methane-oxidizing bacteria (MOB) are a unique group of gram-negative bacteria that are proved to be biological indicator for gas prospecting since they utilize methane as a sole source of carbon and energy. Herein the feasibility of a novel and efficient gas prospecting method using Raman spectroscopy is studied. Confocal Raman spectroscopy is utilized to establish a Raman database of 11 species of methanotrophs and other closely related bacteria with similar morphology that generally coexist in the upper soil of natural gas. After strict and consistent spectral preprocessing, Raman spectra from the whole cell area are analyzed using the combination of principal component analysis (PCA) and Mahalanobis distance (MD) that allow unambiguous classification of the different cell types with an accuracy of 95.91%. The discrimination model based on multivariate analysis is further evaluated by classifying Raman spectra from independently cultivated bacteria, and achieves an overall accuracy of 94.04% on species level. Our approach using Raman spectroscopy in combination with statistical analysis of various gas reservoirs related bacteria provides rapid distinction that can potentially play a vital role in gas exploration.     

Hydrogen-bonding between pyrimidine and water: a vibrational spectroscopic analysis

We present an experimental and a theoretical study on hydrogen-bonding between pyrimidine and water as the H-donor. The degree of hydrogen-bonding in this binary system varies with mixture composition. This was monitored experimentally by polarization-resolved linear Raman spectroscopy with the pyrimidine ring breathing mode nu1 as a marker band. A subsequent quantitative line shape analysis of the isotropic Raman intensity for 24 pyrimidine/water mixtures clearly revealed a splitting into three spectral components upon dilution with water. The two additional peaks have been assigned to distinct groups of hydrogen-bonded species that differ in the number of pyrimidine nitrogen atoms (N) involved in hydrogen-bonding to water hydrogen atoms (H). From the integrated Raman intensities for "free" and "hydrogen-bonded" pyrimidine, a concentration profile for these species was established. Our assignments and interpretations are supported by quantum mechanical calculations of structures and by vibrational spectra for pyrimidine and 10 pyrimidine/water complexes with increasing water content. Also, accurate structure-spectra correlations for different cluster subgroups have been determined; within each particular cluster subgroup the water content varies, and a perfect negative correlation between NH hydrogen-bond distances and nu1 wavenumbers was observed.     

Discrimination of herbal medicines by molecular spectroscopy and chemical pattern recognition

The molecular spectroscopy (including near infrared diffuse reflection spectroscopy, Raman spectroscopy and infrared spectroscopy) with OPUS/Ident software was applied to clustering ginsengs according to species and processing methods. The results demonstrate that molecular spectroscopic analysis could provide a rapid, nondestructive and reliable method for identification of Chinese traditional medicine. It's found that the result of Raman spectroscopic analysis was the best one among these three methods. Comparing with traditional methods, which are laborious and time consuming, the molecular spectroscopic analysis is more effective.