Wang Qi, Zhang Yinming, Lin Hancheng, Zha Shuai, Fang Ruoxi, Wei Xin, Fan Shuanliang, Wang Zhenyuan
Department of Forensic Pathology, College of Forensic Medicine, Xi'an Jiaotong University, Xi'an, Shaanxi, China.
Department of Forensic Pathology, College of Forensic Medicine, Xi'an Jiaotong University, Xi'an, Shaanxi, China.
Forensic Sci Int. 2017 Dec;281:113-120. doi: 10.1016/j.forsciint.2017.10.033. Epub 2017 Nov 8.
Due to a lack of reliable and accurate methods, determining the postmortem interval (PMI) of human skeletal remains is one of the most important and challenging tasks in forensic medicine. In this paper, we studied the changes to bone chemistry with increasing PMI in two different experimental conditions using Fourier transform infrared (FTIR) spectroscopy in conjunction with chemometrics methods Paired bone samples collected from 56 human corpses were buried (placed in soil) and unburied (exposed to the air) for intervals between 76 and 552 days. The results of principle component analysis (PCA) showed the chemical differences of these two cases had a significant influence on the rate of decomposition of the remains. Meanwhile, satisfactory predictions were performed by the genetic algorithm combined with partial least-squares (GA-PLS) with the root mean square errors of prediction (RMSEP) of 50.93days for buried bones and 71.03days for unburied bones. Moreover, the amide I region of proteins and the area around 1390cm, which is associated with fatty acids, were identified with regular changes by GA-PLS and played an important role in estimating PMI. This study illustrates the feasibility of utilizing FTIR spectroscopy and chemometrics as an attractive alternative for estimating PMI of human remains and the great potential of these techniques in real forensic cases with natural conditions.
由于缺乏可靠且准确的方法，确定人类骨骼遗骸的死后间隔时间（PMI）是法医学中最重要且最具挑战性的任务之一。在本文中，我们使用傅里叶变换红外（FTIR）光谱结合化学计量学方法，在两种不同实验条件下研究了随着PMI增加骨骼化学的变化。从56具人类尸体采集的配对骨骼样本被掩埋（置于土壤中）和未掩埋（暴露于空气中）76至552天不等。主成分分析（PCA）结果表明，这两种情况的化学差异对遗骸的分解速率有显著影响。同时，通过遗传算法结合偏最小二乘法（GA-PLS）进行了令人满意的预测，掩埋骨骼的预测均方根误差（RMSEP）为50.93天，未掩埋骨骼为71.03天。此外，GA-PLS识别出蛋白质的酰胺I区域以及与脂肪酸相关的1390cm附近区域有规律的变化，且在估计PMI中发挥重要作用。本研究说明了利用FTIR光谱和化学计量学作为估计人类遗骸PMI的一种有吸引力的替代方法的可行性，以及这些技术在自然条件下实际法医案件中的巨大潜力。
