基于ATR-FTIR和PAC微损快速鉴别颜料层中的蛋白质粘合剂

相较于气相色谱-质谱(GC-MS)和高效液相色谱(HPLC),衰减全反射傅里叶变换红外光谱(ATR-FTIR)能实现绘画颜料中蛋白质种类的“不分离即分析”,从而简化分析步骤和减小文物样品的消耗。这项研究验证了ATR-FTIR用于颜料中蛋白质种类鉴别的可行性。以石青和白垩为矿物颜料,牛奶、明胶和鸡蛋为蛋白质粘合剂制备了新鲜样品和经紫外光老化的模拟文物样品,运用二阶导数光谱和主成分分析建立了模式识别模型。结果表明模拟文物样品中蛋白质的种类能通过新鲜样品建立的模型进行识别。因此,ATR-FTIR在文化遗产领域中蛋白质种类的微损和快速鉴别具有巨大的潜力。     

Molybdenum(VI) Oxide-Modified Silica Gel as a Novel Sorbent for the Simultaneous Solid-Phase Extraction of Eight Metals with Determination by Flame Atomic Absorption Spectrometry

A silica-based inorganic sorbent was synthesized by the thermal decomposition of ammonium heptamolybdate on silica and applied for the preconcentration and simultaneous determination of Cd, Co, Cr, Cu, Fe, Mn, Ni, and Pb in river water samples using a column system with flame atomic absorption spectrometry. Attenuated total reflection-Fourier transformation infrared spectroscopy, scanning electron microscopy, and electron dispersive spectroscopy were used for sorbent characterization. The effects of pH, sample volume, eluent type, eluent concentration, eluent volume, sample flow rate, and matrix ions (Al, Bi, Ca, Mg, and Zn) on the recovery of the metals in model solutions were investigated. The adsorption capacities (µmol g^?1) of SiO₂-MoO₃ were 88.96 (Cd), 169.69 (Co), 153.85 (Cr), 188.88 (Cu), 179.05 (Fe), 163.81 (Mn), 136.31 (Ni), and 38.61 (Pb). The detection limits of the method were 9.09, 10.82, 10.77, 49.57, 31.64, 6.40, 8.86, 19.15?µg L^?1 for Cd, Co, Cr, Cu, Fe, Mn, Ni, and Pb, respectively, with a preconcentration factor of 25. The developed method was used for the determination of the target metals in real samples and the recoveries for spiked samples were found to be from 91.2% to 102.9%.     

薰衣草精油的衰减全反射红外光谱辨别分析

为建立薰衣草精油品种品质的快速辨别分析模型,采用衰减全反射红外光谱法测定三个品种共96个薰衣草精油样品,对原始光谱数据求二阶导数,通过方差计算,确定1 750～900 cm-1波长段为判别分析用数据。分析结果表明,主成分分析(PCA)基本能实现精油品种区分,前三个主成分主要代表着酯、醇和萜类物质。使用68个样品的校正集建立正交偏最小二乘判别分析(OPLS-DA)模型,三个品种薰衣草精油的回归曲线测定系数分别为0.959 2, 0.976 4, 0.958 8,验证集中三个品种精油预测均方根误差(RMSEP)分别为0.142 9, 0.127 3, 0.124 9,OPLS-DA法建立的模型对校正集和验证集的判别率和预测率都达到100%,模型对薰衣草精油品种品质有很好的识别能力。为薰衣草精油品种品质提供一个快速、直观的方法。     

中国人头发纤维在UVA紫外光老化中的光谱学研究

生活中,日光中的紫外辐射是导致头发光老化/光损伤的重要环境因素。长时间光照可使染发和天然发出现包括颜色褪变在内的退行性变化。以中老年人的自然灰发为样本来源,通过分离和人工漂染处理,获得了包括自然发色、漂白和染黑的六种头发类型,经过UVA(320～400 nm)紫外光老化,采用漫反射光谱、三维荧光光谱和衰减全反射傅里叶变换红外光谱对头发纤维的老化特征进行无损分析,结合头发中光产生过氧化氢的定量分析,探讨了不同发色和漂染处理对头发耐光性的影响。结果表明,UVA辐照可通过Ⅱ型电子转移机制诱导头发中的光敏基团产生过氧化氢,导致纤维表面蛋白和色素分子的光氧化降解。自然发色与漂染发在光老化中的颜色变化不同： 灰发和白发主要发生光黄化,人工染发和漂白发分别发生光褪色和光漂白。高湿度环境能加速头发的光降解。化学漂染处理会使头发中的光致过氧化氢水平升高,使纤维处于较高的氧化压力从而影响头发的光稳定性;而头发中的黑色素分子,包括天然黑色素和染发剂的人工黑色素,可能具有自由基产生与清除双重性。研究结果为建立中国人头发光损伤的光谱学评价方法和进一步研发针对国人发质的染护发产品提供了重要的实验基准数据。     

Low-Carbohydrate,High-Protein,and Gluten-Free Bread Supplemented with Poppy Seed Flour: Physicochemical,Sensory, and Spectroscopic Properties

Background: This study aimed to determine the effect of poppy seed flour (PF) on the physicochemical and spectroscopic properties of low-carbohydrate, high-protein, and gluten-free bread. Methods: The changes at the molecular level were assessed in bread using attenuated total reflectance Fourier transform infrared spectroscopy (ATR-FTIR). Bread prepared with buckwheat, flaxseed, and pea protein was enriched with PF at a concentration of 5–15%. Results: The results showed that the pasting parameters of dough supplemented with PF were significantly decreased compared to the control sample. The obtained bread samples were characterized by good quality and had 14.6% of carbohydrate, 16.3% of protein, 10.2% of fiber, and 4.0% of fat, with a caloric value of 177 kcal/100 g. The addition of PF had little influence on crumb mechanical properties. The ATR-FTIR analyses revealed spectral changes in the region related to protein and carbohydrate structures, as well as changes in band intensity characteristic of α-1,4-glycoside and α-1,6-glycoside bonds. The analyses showed that the main starch skeleton remained clearly visible. Conclusions: PF up to 10% can be potentially applied as a functional ingredient in the production of bread based on buckwheat and linseed flour. Such low-carbohydrate bread can be particularly useful to diabetics.     

Surface modification of polypropylene under argon and oxygen-RF-plasma conditions

Polypropylene fabrics samples were surface functionalized under Ar and O₂ RF plasma conditions. Survey and high resolution photoelectron spectroscopy and attenuated total reflectance FTIR comparative evaluation of virgin and plasma treated substrat surfaces, and their pentafluorophenyl hydrazine-derivatized correspondents, indicate that both Ar and O₂-discharge treated PP surfaces undergo intense oxidation. C=O, O−C=O, and C−O linkages were identified on both inert and reactive gas plasma exposed surfaces. It was found that the relative surface atomic concentrations and the relative ratios of newly created functionalities are controlled by the external plasma parameters (RF power and treatment time). The oxidation of Ar-plasma treated surfaces has been related toex situ post plasma mechanisms. Dynamic contact angle measurements from unmodified and plasma exposed substrates demonstrated the presence of increased surface polarity, and its dependence on plasma parameters. AFM evaluations of plasma treated samples indicate the presence of rough surface morphologies. Paper based on the results presented during the workshop of the Engineering Research Center for Plasma-Aided Manufacturing held in Madison, Wisconsin, in Spring 1996.     

Effect of silica nanofillers on isothermal crystallization of poly(vinyl alcohol): In-situ ATR-FTIR study

Isothermal crystallization behavior of poly(vinyl alcohol) (PVA) in the presence and absence of silica nanoparticles was systematically investigated using in-situ attenuated total reflectance Fourier-transform infrared (ATR-FTIR) spectroscopy. The content, size, and surface characteristics of silica nanoparticles were considered as main factors affecting the crystallization behavior, and the effect of annealing time and temperature was also examined. First, very low concentrations of silica nanoparticles (less than 0.5 wt%) could accelerate the crystallization process, whereas higher silica loadings reduced the degree of crystallization. In the PVA/silica (0.5 wt%) nanocomposites, 22-nm silica nanoparticles provided the most suitable interparticle space for nucleation and crystal growth. Compared with hydrophobic silica nanoparticles, hydrophilic silica nanoparticles are favorable to achieve higher crystallinity due to the increased chemical affinity in the nanocomposites. The degree of crystallization became higher with increasing annealing time and it was also enhanced in a high-temperature region. When 0.5 wt% of 22-nm silica nanoparticles was used as a nucleating agent for the crystallization of PVA, the crystallinity of nanocomposites was ca. 20% higher than that of pristine PVA.     

ATR-FTIR法在皮革产品中的应用

目前市售皮革分为动物皮革和人造革两类.皮革是动物皮经加工后制成,具有动物皮肤特点.人造革也称假皮革是指合成革或外观貌似真皮实际上由化工原料人工合成的产品,其本身不是动物皮.怎样鉴别真皮与人造革方法有很多,如手摸法、眼看毛孔花纹等.在日常消费中,由于市场上有的皮革产品在生产过程中在表面涂了一层有机材料以及其它处理,普通消费者单凭借手感和经验目测来判断,往往不容易辨别真假.随着人们消费皮革制品的需求增加以及市售皮革制品.在有大量难辨真伪的仿皮革的人造革制品,因此鉴别各行业中的皮革受到越来越多的关注.本文运用ATR-FTIR技术对皮革材料的结构成分进行分析,依据不同物质所得到的谱图不同,就能准确、快速地分辨真皮革和人造革.     

Transport of Propylene Carbonate-LiTFSI Electrolytes in P(VDF-HFP) Using Time-resolved ATR-FTIR Spectroscopy: Diffusion Coefficients and Molecular Interactions

The time-resolved attenuated total reflectance-Fourier transform infrared(ATR-FTIR) spectroscopy is employed to investigate the transport mechanism of gel electrolytes by monitoring the diffusion behavior of propylene carbonate-lithium bis(trifluoromethylsulfonyl)imide(PC-LiTFSI) solution through poly(vinylidene fluoride-co-hexafluoropropylene)(P(VDF-HFP)) films. Fickian behavior has been observed for both TFSI-and PC. Higher temperature leads to faster diffusion of TFSI~-and PC, which could be related to the increased free volume in P(VDF-HFP)matrix and rapid molecular movements upon heating. Various molecular interactions among LiTFSI, PC and P(VDF-HFP) have been recognized.During the diffusion process, PC molecules, in the form of small clusters, can firstly diffuse through the P(VDF-HFP) film and interact with P(VDFHFP) by dipole-dipole interaction, acting as the plasticizer. Then, Li~+ diffuses into P(VDF-HFP) with the help of ion-dipole interactions between Li~+and C=O of PC. Meanwhile, TFSI-diffuses through the polymer matrix in solvation states. In addition, slight ion-dipole interactions between Li~+and P(VDF-HFP) have been observed as well. Results in this work contribute to a better understanding of transport process in gel polymer electrolytes for lithium-ion batteries and support the development of improved gel polymer electrolytes by rationally regulating molecular interactions.