Detection of fresh palm oil adulteration with recycled cooking oil using fatty acid composition and FTIR spectral analysis

There is a growing concern over the food safety issue related to increased incidence of cooking oil adulteration with recycled cooking oil (RCO). The objective of this study was to detect fresh palm olein (FPO) adulteration with RCO using fatty acid composition (FAC) and Fourier-transform infrared spectroscopy (FTIR) spectral analyses combined with chemometrics. RCO prepared in the laboratory was mixed with FPO in the proportion ranged from 1% to 50% (v/v) to obtain the adulterated oil samples (AO). FACs for FPO, RCO, and AO were determined using gas chromatography equipped with a flame ionization detector (GC-FID). The compositions of most fatty acids in RCO lied within the normal ranges of Codex standard, except for C8:0, C10:0, C11:0, C15:0, trans C18:1, and polyunsaturated fatty acids (PUFAs), C20:5. PUFAs showed a consistent decreasing trend with increasing magnitude of change with respect to increasing adulteration level and thus might be a good indicator for detecting FPO adulteration with RCO. The evaluation parameters (coefficient of determination, root mean standard error) of the FTIR-partial least square (PLS) model of palm oil adulteration with recycled oil are R² = 0.995 and 3.25, respectively. For FTIR spectral analysis, the distinct variations in spectral regions and aberrations in characteristic bands between FPO and RCO were observed. The optimized PLS calibration model developed from normal spectral of the combined region at 3602–3398, 3016–2642, and 1845–650 cm^?1 overpredict the adulteration level. On the other hand, the discriminant analysis classification model was able to classify the FPO and AO into two distinct groups. Improvement of the principles of combined techniques in authenticating AO from fresh oil is beneficial as a guideline to detect adulteration in cooking oil.     

基于光谱分类模型的保险杠物证无损研究

采用中红外光谱结合化学计量学的方法对车用保险杠碎片进行鉴别，分别对52个车用保险杠碎片样本的全波段光谱数据、指纹区光谱数据和主成分分析降维后的光谱数据建立Fisher判别分析和K近邻算法2种分类模型，并对分类结果进行比较。结果表明，主成分分析提取特征变量后构建的分类模型，分类的准确率更高，对聚丙烯（PP）、PP/滑石粉、PP/滑石粉/碳酸钙（CaCO₃）3种类型的样本分类准确率达到92.3 %，对PP/滑石粉类型中的10种品牌样本分类准确率达到88.9 %，分类结果理想；在构建的2种分类模型中，Fisher判别分析模型的分类率远高于K近邻算法模型，分析认为K近邻算法模型受到样本不均衡的影响；中红外光谱结合化学计量学可以实现对车用保险杠碎片的准确区分，且满足快速、无损的检验要求。     

Properties of starch–cellulose fiber films produced by tape casting coupled with infrared radiation

Tape casting is a suitable process for large-scale production of biodegradable films. This study presents a comparison of three drying procedures of starch–cellulose films: i) conduction drying, ii) infrared drying (42.3?W?m^?2, higher infrared heating power damaged the films), and iii) conduction-infrared drying. All the drying procedures were performed at approximately 60°C. Drying times from the second and third methods were close to 1?h, half the time observed for conduction drying. Films from the second and third methods showed similar hygroscopicity (0.15?g.?g^?1, RH 43%), tensile strength (31.3?MPa, RH 58%), and glass transition temperature (?12.13°C, RH 43%).     

透明红外硫系薄膜非均匀性检测及影响因素

薄膜非均匀性的无损检测对于制备大面积高质量的红外透明薄膜尤为重要。针对红外薄膜光学均匀性难以获取的困难,提出了一种同时获得单层透明红外薄膜厚度和折射率均匀性的无损检测方法。实验上,通过磁控溅射法在二氧化硅衬底上制备了厚度约1.4μm红外透明Ge-Sb-Se硫系薄膜,然后在该薄膜上标定出36个80μm×80μm区域,利用显微傅里叶红外光谱仪测得该36个区域的透射谱,通过分段滤波的方法滤除背景噪声,运用改进的Swanepoel方法计算得到了薄膜每一个区域的厚度和折射率,进而精确获得该薄膜的厚度和折射率均匀性,结果表明精度优于0.5%。     

TG-FTIR and Py-GC/MS study of the pyrolysis mechanism and composition of volatiles from flash pyrolysis of PVC

To facilitate the reuse and recycling of polyvinyl chloride (PVC) to achieve sustainable development and new industrialization, the composition and mechanism of formation of volatiles during the flash pyrolysis of PVC were studied by thermogravimetry-Fourier transform infrared (TG-FTIR) and pyrolysis-gas chromatography/mass spectrometry (Py-GC/MS). TG and derivative thermogravimetry (DTG) analyses indicated two main degradation stages during flash pyrolysis of PVC, namely dehydrochlorination of PVC and decomposition of dechlorinated-PVC. Simultaneously, the FTIR results revealed that the main functional groups in the pyrolysis process were H–Cl, -C-Cl, C–H, CH, and aromatic groups. The relative content of main volatiles was determined by Py-GC/MS, and decreased in the following order: aromatics > alkenes > hydrogen chloride (HCl) > chlorinated hydrocarbons. Specifically, the relative content of aromatics was as high as 76.790–81.809%, while that of HCl was in the range of 3.016–3.096%. The carbon number distribution and the relative content of main products obtained from the flash pyrolysis of PVC at different final temperatures were also analysed. According to the experimental results, the mechanism of formation of the main volatiles based on free-radical reactions was deduced in detail. Therefore, this study provides further details for deepening the understanding of the PVC pyrolysis process.     

煤红外快速热解过程中床层对二次反应的影响

针对煤快速热解研究中样品添加量少(mg级)、焦油收集难等问题，本研究利用压片法制备微薄厚度(mm级)的煤层，并采用红外加热装置考察大添加量(g级)、微薄煤层的快速热解特性。对比堆积煤样和不同煤压片厚度(1.5~3 mm)与个数(1~2)的压片煤样热解特性发现，压片煤层热解过程的二次反应受到明显抑制，焦油产率急剧增加，在1000℃时达9.96%，为格金分析的1.5倍，实现油气产量的同步增长。模拟蒸馏分析发现，堆积状态下焦油以沥青质为主，而微薄煤层制焦油含大量轻油、酚油、萘油、洗油和蒽油。GC-MS和FTIR分析表明，随煤层厚度和个数的减少，焦油组分和含量提高，芳香烃类和含氧官能团吸收增加，进一步验证煤快速热解过程中煤层厚度对焦油产率和品质的影响，揭示在二次反应充分抑制下煤高温热解的初级反应特性。     

Investigation into eddy current pulsed thermography for rolling contact fatigue detection and characterization

This paper reports on the use of eddy current pulsed thermography (ECPT) for detection and characterization of rolling contact fatigue (RCF). Detection mechanisms with eddy currents and heat propagation effects were discussed with RCF modeled as a simple angled defect. Two different angled defects were studied through numerical simulations and experimentally by using uniform magnetic field (UMF) excited by Helmholtz coils. Finally, a rail sample with RCF defects was inspected using UMF excitation. It is shown that ECPT with UMF excitation provides an efficient and robust method to detect angled defects, compared with nonuniform magnetic field (NUMF) excitation.     

Review of pulsed thermal NDT: Physical principles,theory and data processing

This paper summarizes the basics of pulsed thermal nondestructive testing (TNDT) including theoretical solutions, data processing algorithms and practical implementation. Typical defects are discussed along with 1D analytical and multi-dimensional numerical solutions. Special emphasis is focused on defect characterization by the use of inverse solutions. A list of TNDT terms is provided. Applications of active TNDT, mainly in the aerospace industry, are discussed briefly, and some trends in the further development of this technique are described.     

The effect of maturity and tissue on the ability of mid infrared spectroscopy to predict the geographical origin of banana (Musa Cavendish)

The objective of this study was to evaluate the effect of sample presentation (tissue type) and maturity (ripe and unripe) on the classification of banana (Musa Cavendish) samples sourced from two different geographical regions and analysed using mid infrared (MIR) spectroscopy. The coefficient of determination (R²) and the standard error of cross-validation (SECV) obtained using partial least squares discriminant analysis were 0.83 (0.33), 0.75 (0.25) and 0.94 (0.19) for the prediction of maturity, geographical origin and tissue type, respectively. No effect of either of type of tissue (e.g. pulp or peel) or maturity was observed. The results of this study demonstrated that MIR spectroscopy might be used to classify the origin of the banana samples at different degrees of ripeness. However, one of the limitations of this study is on the number of samples analysed and further validation must be recommended using samples from other sources, regions and harvest seasons.     

面源红外诱饵对抗红外制导导弹干扰策略研究

面源红外诱饵使用的过程中,合理有效的干扰策略是干扰红外制导导弹的关键,针对这一问题,通过理论分析与仿真模拟相结合得到面源红外诱饵对抗红外制导导弹的干扰策略。首先以红外成像制导导弹为例,介绍红外制导导弹的仿真模型,然后将攻击过程分为锁定前与锁定后,以命中率为评价指标,得到两个阶段下的最佳干扰策略,包括诱饵的最佳释放时机、释放间隔以及载机应采取的机动动作等。