Investigation of Lignins by FTIR Spectroscopy

Summary: Applying special computer mathematical treatments to increase resolution of experimental spectra there were established a set of stable characteristic bands for isolated softwood lignins. In the 740–1620 cm⁻¹ spectral range the band maximum positions did not change but values of bandwidths and peak intensities were varied in limits 15% and 32%. After analysis of the infrared spectra of 30 investigated samples a softwood lignin spectral model was constituted. This model allowed to clear discrepancies in the bands parameters of different mild isolated (lignins of Bjorkman, Pepper and Freudenberg), dioxane and technical lignin spectra. It was helpful for studying lignin structure changes during degradation procedures.     

傅里叶变换中红外光谱法检测脑胶质瘤

采用傅里叶变换衰减全反射中红外光谱法检测了19例液氮冻存的脑胶质瘤离体组织样品(星形细胞瘤10例, 少枝-星形细胞瘤9例), 对得到的红外光谱进行分析发现, 恶性程度不同的星形细胞瘤组织的红外光谱存在差异, 并且不同类型的脑胶质瘤组织的红外光谱也表现出较为明显的区别, 因此可以根据各个特征吸收峰的峰位、 峰形及谱峰强度等信息来区分脑胶质瘤, 并初步鉴别脑胶质瘤的性质. 研究结果表明, 通过某些特征吸收峰峰位的变化来鉴别星形细胞瘤和少枝-星形细胞瘤与病理诊断结果的符合率约为80%, 说明傅里叶变换衰减全反射中红外光谱法有望发展成为一种对样品无损伤、 快速的脑肿瘤诊断新方法.     

Development of a Novel Acoustic Spectroscopy Method for Detection of Eggshell Cracks

Non-destructive testing (NDT) for eggshell faults is highly important for the egg industry, as cracked eggs account for around 3% of total production. The most commonly used method at present, candling, is labor intensive, while computer vision systems are expensive and complicated. In this paper, we present a simple, yet efficient, novel method for eggshell crack detection by acoustic spectroscopy. Altogether, 693 sound recordings were evaluated by different classification methods. The results show a cross-validated 2.1% total classification error, with only 0.87% false positive rate, which is the crucial metric for fresh eggs. Adapting the developed method to an industrial setting may lead to a reliable, fast and cost-effective detection method.     

Ensemble Regression Coefficient Analysis for Application to Near-Infrared Spectroscopy

A new variable selection method called ensemble regression coefficient analysis is reported on the basis of model population analysis. In order to construct ensemble regression coefficients, many subsets of variables are randomly selected to calibrate corresponding partial least square models. Based on ensemble theory, the mean of regression coefficients of the models is set as the ensemble regression coefficient. Subsequently, the absolute value of the ensemble regression coefficient can be applied as an informative vector for variable selection. The performance of ensemble regression coefficient analysis was assessed by four near infrared datasets: two simulated datasets, one wheat dataset, and one tobacco dataset. The results showed that this approach can select important variables to obtain fewer errors compared with regression coefficient analysis and Monte Carlo uninformative variable elimination.     

Ultrafast Spectroscopy Studies on Thickness Dependence of Acoustic Phonon Modes in Silver Nanoprisms

Time-resolved transient absorption technique is used to investigate the thickness dependence of acoustic phonon modes of silver nanoprisms with two thicknesses, 7.8 ± 1.2 and 8.5 ± 0.69 nm, and a similar bisector length of 31.4 ∼ 31.6 nm. Coherent acoustic phonon signals are observed. A new acoustic phonon frequency within 7.81 cm⁻¹ ∼ 11.7 cm⁻¹ is found and this phonon mode is associated with the thickness of the nanoprism. Another phonon frequency between 1.95 cm⁻¹ and 1.71 cm⁻¹ is also observed, and its origin can be associated with the bisector length of the nanoprism.     

表面增强喇曼光谱技术应用于生物体系的最新进展

本文综述了近几年来表面增强喇曼光谱技术应用于以下几个方面的生物体系的最新资料：（１）核酸及其组分，（２）蛋白质及其组分，（３）儿茶酚胺，（４）有色生物质，（５）膜制品。总结了表面增强喇曼光谱技术的一般性结论，并对这一技术应用于生物体系的发展作了展望     

傅里叶变换红外光谱及其联用技术在反应研究中的新进展

综述了傅里叶变换红外光谱（ＦＴＩＲ）及其联用技术在界面与电化学反应、生物反应、催化反应和动力学研究中的最新进展，参考文献５７篇。     

表面增强拉曼光谱应用于标记免疫多组分检测

作为一种新型的免疫检测方法, 表面增强拉曼光谱(SERS)技术被应用于标记免疫多组分检测. 以多种不同的标记分子(苯硫酚, 联吡啶类分子, 氰基吡啶类分子)分别标记多种不同免疫金溶胶, 通过抗体抗原之间所具有的特异吸附性, 进一步组装“固相抗体-待测抗原-标记免疫金溶胶”多组分三明治复合体系. 利用表面增强拉曼光谱谱峰较窄, 具有较强的分辨率及高灵敏度的特点, 对多种标记分子特征谱峰进行分析判断, 从而识别所加入的多种抗原, 实现SERS标记免疫多组分同时检测的目的, 并对其中氰基吡啶类分子的吸附进行了探讨.     

激光光热干涉光谱分析方法研究

本工作设计了一种新的激光光热干涉光谱装置,类似于Mach-Zehnder干涉仪的光路构型,采用探测束聚焦和泵浦束与探测束相交的光学结构,光路容易调整稳定性较好.文章讨论了方法的原理,详细研究了影响光热干涉信号的实验参数,获得结晶紫的检测下限为8.0×10~(-8)mol/L,相应的最小吸光度为3.6×10~(-6)。     

Investigation of Molecular Alkali Tetrafluorido Aurates by Matrix-Isolation Spectroscopy

Molecular alkali tetrafluorido aurate ion pairs M[AuF₄] (M=K, Rb, Cs) are produced by co-deposition of IR laser-ablated AuF₃ and MF in solid neon under cryogenic conditions. This method also yields molecular AuF₃ and its dimer Au₂F₆. The products are characterized by their Au–F stretching bands and high-level quantum-chemical calculations at the CCSD(T)/triple-ζ level of theory. Structural changes in AuF₄⁻ associated with the coordination of the anion to different alkali cations are proven spectroscopically and discussed.     

Vibration Spectroscopy Stability Investigation of 12-Tungstosilicic Acid Solution

Heteropoly acids (HPA) attract the attention of large variety of scientists, due to HPA’s extraordinary interesting properties and possible application fields. 12-tungstosilicic acid (WSiA), the Keggin type HPA, has some promising characteristic to be used in catalytic processes, but with not well-defined stability. Raman spectroscopy was used for in situ analysis of WSiA hydrolysis in detail in a wide pH range of 1–12. Raman spectroscopy is able to give an almost immediate response/spectrum as a representation of the exact profile/composition of the solution. This method and FTIR spectroscopy, as a complementary technique, enabled recording of the solid and liquid phases of the same sample under different conditions. Our results confirm that the decomposition pathways of WSiA in solution proceed via the formation of the lacunary monovacant anion at pH > 6.4. This anion is a major constituent in pH range up to 9.5. With further increases in pH this species convert to the trivacant lacunary anion. The total decomposition of the Keggin anion to silicate and tungstate occurs at pH > 11.0. The results of the performed study contribute to understand the behavior of WSiA in the water–methanol solution, as the model system of aqueous-organic system. It is concluded that addition of methanol in aqueous solution of WSiA leads to expansion of the pH region where Keggin anion is stable up to 8.1 and above this pH value, precipitation occurs. The obtained data clarify the stability range of WSiA in both water and water–methanol solutions, as well.     

近红外反射光谱技术在动物营养研究中的应用进展

介绍了近红外反射光谱(NIRS)技术的基本原理,着重评述了其在动物营养研究中的评价动物饲料及日粮的营养价值、估测动物采食量及消化性能、估测动物的营养健康状况等方面的应用进展(引用文献37篇)。     

Application of Ligand Field Spectroscopy to Problems of Chemical Bonding in Solids

Selected examples (dⁿ systems) are presented to illustrate the interpretation of ligand field spectra (remission spectra) of solid inorganic compounds. In particular, this article demonstrates possible means for the investigation of weak cooperative interactions between transition metal coordination polyhedra and for the determination of the cation distribution in crystal lattices. The information value of the spectroscopic method to the chemist is critically discussed.     

Electrochemical Investigation of some Flavonoids in Aprotic Media

Cyclic voltammerty data for the oxidation of 15 flavonoids in acetonitrile have been presented. Up to three peaks in different potential regions appear in the CV curves, depending on the structure of a flavonoid. The peak in the first potential region (+0.79÷+1.03 V vs SCE) occurs when a flavonoid molecule has an o-dihydroxy moiety in the ring A or B. From the data in the literature, the formation of o-quinone is responsible for the occurrence of the peak. When the o-dihydroxy moiety is in ring B and the hydroxyl group is at position 3, the second peak in the potential region+1.08÷+1.32 V, is present. It is an agreement that the peak is due to oxidation of benzofuranone derivative formed in reaction of o-quinone with water. Molecules with an o-quinone moiety located in ring A seem to be less reactive, and the peak in the second potential region does not occur. However, the existence of an o-quinone in the ring B is not necessary for the peak in the second potential region to be present. The oxidation of kaempferol and morin, which have hydroxyl groups at positions 3 and 4’, takes place at 0.98 V and 0.97 V, respectively, and leads to the formation of p-quinone methide. We have shown that the peak in the second potential region also appears when the hydroxyl group in the flavonoid molecule is only at position 3 or at position 4’. For 3-hydroxyflavone and apigenin, which are oxidized at +1.10 V and 1.49 V respectively, p-quinone methide was detected after controlled potential bulk electrolysis. A mechanism which includes the reaction of the carbon radical with a trace of water has been proposed. For flavonoids that have an o-dihydroxy moiety in ring B and the hydroxyl group at position 3, two oxidation peaks are observed in the CV curves in the second potential region for low scan rates (below 0.1 V s⁻¹). An explanation of this behavior has been proposed.     

离子液体酸性的红外光谱探针法研究

以吡啶和乙腈分子为探针, 使用红外光谱法研究了常用室温离子液体的酸性. 采用吡啶为探针分子时, 出现的～1450 cm^－1、～1540 cm^－1吸收带可以分别指示离子液体的Lewis、Brønsted酸性；采用乙腈为探针分子时, ～2253 cm^－1的C≡N伸缩振动向高波数移动并伴有新峰的出现，可以指示离子液体的Lewis酸性。可以通过比较吡啶探针～1450 cm^－1吸收带的峰位置对离子液体的Lewis酸强度进行排序，并且可以用乙腈探针更灵敏地区分出不同离子液体的Lewis酸的强度，使用该方法研究了离子液体的结构对其Brønsted / Lewis酸性的影响。     

红外光谱法在双亲性化合物水溶液体系研究中的应用

浓度，温度，压力，体系组分及不同分子间相互作用等因素对双亲性化合物分子在水溶液体系中的聚集状态及相变过程均有影响。本文综述了富里叶变换红外光谱方法在这一研究领域内应用十余年间的研究进展。     

比较红外光谱法与拉曼光谱法在聚氯乙烯鉴定中的应用

聚氯乙烯(polyvinyl chloride, 简称PVC)是五大通用塑料之一,自20世纪70年代就开始得到了大量的工业生产[1].相比于其它品种的塑料,PVC具有难燃、抗化学药品性、优良的电绝缘性和较高的强度等特点,在建筑材料、食品包装和农用材料等领域具有非常广泛的用途.目前工业及日常生活对高分子化合物的依赖越来越大,因此,对聚合物类型的快速鉴别成为许多用户及厂家所迫切需要解决的问题.     

强度调制光电流谱/光电压谱及其应用

本文介绍了强度调制光电流谱/光电压谱(IMPS/IMVS)的基本原理和测试方法,综述了IMPS/IMVS在各个领域中的研究进展,特别是在染料敏化太阳电池和半导体电极中电子传输动力学的应用,评述了研究过程中的问题和存在的争议,并对IMPS/IMVS的未来应用进行了展望。     

Investigation of Temperature Effects on Cyclodextrin Compounds Through FT-IR Spectroscopy

Abstract

The infrared spectra of inclusion compounds of terephthalaldehyde and two aromatic esters with α- or β- cyclodextrin are studied. A wide range of temperatures provides significant modifications of the spectra which are explained by rotational isomerism of the guest molecule.