Abstract：
The significance of biomechanical analyses for forensic time since death estimations has recently been demonstrated. Previous biomechanical analyses successfully discriminated post-mortem brain tissue from tissue with a post-mortem interval of at least one day when held at 20 °C. However, the practical utility of such analyses beyond day one at 20 °C was limited. This study investigates the storage, loss, and complex shear modulus of various brain regions in sheep stored at 4 °C in 24-hour intervals over four days post-mortem using rheometry tests. The aim is to identify the critical biomechanical tissue property values to predict post-mortem time and assess the temperature sensitivity of the rheometry method by comparing results to recent findings at 20 °C. Thirty sheep brains were examined, including the frontal lobe, parietal lobe, anterior and posterior deep brain, superior colliculi, pons, medulla, and cerebellum. Rheometry tests were conducted, and receiver operator characteristic analyses were employed to establish cut-off values. At 4 °C storage, all investigated biomechanical properties of the examined brain regions remained stable for at least one day post-mortem. Using cerebellar samples stored at 4 °C, a post-mortem interval of at least two days could be determined with excellent diagnostic ability. Complex shear modulus values below 1435 Pa or storage modulus values below 1313 Pa allowed prediction of two or more days post-mortem. Comparisons between 4 °C and 20 °C revealed brain region-specific results. For instance, the complex shear moduli of the anterior deep brain at 4 °C were significantly higher on all individual testing days when compared to 20 °C. In contrast, the combined medulla and pons samples were similar on each day. Rheometry testing of brain tissue consistently stored at 4 °C since death proved valuable for forensic time since death estimations starting from two days after death.
摘要：
自从死亡估计以来，生物力学分析对法医时间的重要性最近得到了证明。先前的生物力学分析成功地将死后脑组织与在20°C下保持至少一天的死后间隔的组织区分开。然而,在20°C下超过第一天的这种分析的实际应用是有限的。这项研究调查了储存，损失,以及使用流变仪测试在宰后四天内以24小时间隔在4°C下储存的绵羊中各个大脑区域的复杂剪切模量。目的是确定关键的生物力学组织特性值以预测死后时间，并通过将结果与20°C的最新发现进行比较来评估流变测定法的温度敏感性。检查了30只绵羊的大脑，包括额叶,顶叶,前脑和后脑深部,上丘，pons,髓质,还有小脑.进行了流变测试，和接收器操作员特征分析被用来建立截止值。在4°C储存时，所有受检脑区的生物力学特性在死后至少1天保持稳定.使用储存在4°C的小脑样本，可以确定至少两天的验尸间隔具有出色的诊断能力。低于1435Pa的复合剪切模量值或低于1313Pa的储能模量值允许预测死后两天或更多天。4°C和20°C之间的比较揭示了大脑区域特定的结果。例如,与20°C相比，在所有单独的测试日中，4°C下前深部大脑的复杂剪切模量均显着较高。相比之下,每天合并的髓质和脑桥样本相似。自从死亡后两天开始的死亡估计以来，一直在4°C下保存的脑组织的流变测试对法医时间很有价值。
