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logy of the People's Republic of China, which positively contributes to the development of basic research and the improvement of overall level in forensic genetics in China.

Objective To assess the feasibility of the rbcL sequence of chloroplast DNA as a genetic marker to identify Cannabis sativa L. Methods The rbcL sequences in 62 Cannabis sativa L. samples, 10 Humulus lupulus samples and 10 Humulus scandens DNA samples were detected, and 96 rbcL sequences of the Cannabaceae family were downloaded from Genbank. Sequence alignment was performed by MEGA X software, the intraspecific and interspecific Kimura-2-Parameter （K2P） genetic distances were calculated, and the system clustering tree was constructed. Results The rbcL sequence length acquired by sequencing of Cannabis sativa L. and Humulus scandens were 617 bp and 649 bp, respectively, and two haplotypes of Cannabis sativa L. were observed in the samples. The BLAST similarity search results showed that the highest similarity between the sequences acquired by sequencing and Cannabis sativa L. rbcL sequences available from Genbank was 100%. The genetic distance analysis showed that the maximum intraspecific genetic distance （d system cluster analysis could be a reliable and effective detection method for Cannabis sativa L. Avelumab chemical structure identification in forensic investigation.

Objective To study the accuracy of Nolla method for age estimation of Northern Chinese Han children aged between 5.00 and 14.99 years based on original transformation tables and multiple regression model. Methods A total of 2 000 orthopantomographs （OPGs） were collected from the Hospital of Stomatology, Xi'an Jiaotong University, including 1 000 males and 1 000 females. Development stage of 7 left mandibular permanent teeth （except third molars） was assessed based on Nolla method, then age estimation was conducted through transformation tables and multiple regression model, respectively. Firstly, the development stage results of 7 permanent teeth were added up and the estimated age was obtained through the original transformation tables. Secondly, 80% of the samples （80 males and 80 females in each age group） were randomly selected from 2 000 OPGs as the train set. The chronological age of the selected patients was taken as the dependent variable, while gender and the development stage results of 7 permanenr age estimation.

Objective To establish the basic data for estimating minimum postmortem interval （PMImin） of heavily decayed and skeletonized remains by studying the development of Dermestes maculatus DeGeer （Coleoptera Dermestidae）. Methods The developmental stages of Dermestes maculatus were observed at four constant temperatures of 20 ℃, 24 ℃, 28 ℃ and 32 ℃, and the changes in body length were also examined as the biological indicator to estimate larval day-age and instar. Results The total developmental time from egg to adult at 20 ℃, 24 ℃, 28 ℃ and 32 ℃ were （126.7±10.6） d, （69.4±8.2） d, （50.4±8.4） d and （49.6±6.5） d, respectively. The body length increased gradually, but changed irregularly as a whole. Conclusion The study provides basic data on the development and growth of Dermestes maculatus, especially on its developmental duration as a significant value for estimating PMImin of heavily decayed and skeletonized remains. Nevertheless, the change of body length is not found to be the best biological indicator for ical indicator for instar determination.

Objective To study the changes of metabolites in serum and tissues （kidney, liver and heart） of mice died of acute tetracaine poisoning by metabolomics, to search for potential biomarkers and related metabolic pathways, and to provide new ideas for the identification of cause of death and research on toxicological mechanism of acute tetracaine poisoning. Methods Forty ICR mice were randomly divided into control group and acute tetracaine poisoning death group. The model of death from acute poisoning was established by intraperitoneal injection of tetracaine, and the metabolic profile of serum and tissues of mice was obtained by ultra-high performance liquid chromatography-electrostatic field orbitrap high resolution mass spectrometry （UPLC-Orbitrap HRMS）. Multivariate statistical principal component analysis （PCA） and orthogonal partial least square-discriminant analysis （OPLS-DA） were used, combined with t-test and fold change to identify the differential metabolites associated with death from acute tetracisoning are expected to be candidate biomarkers for this cause of death. The results can provide research basis for the mechanism and identification of acute tetracaine poisoning.

Objective To observe the skin ultrastructure change of electric shock death rats and to test the expression changes of hypoxia-inducible factor-2α （HIF-2α） and heart type-fatty acid-binding protein （H-FABP） of myocardial cells, in order to provide basis for forensic identification of electric shock death. Methods The electric shock model of rats was established. The 72 rats were randomly divided into control group, electric shock death group and postmortem electric shock group. Each group was divided into three subgroups, immediate （0 min）, 30 min and 60 min after death. The skin changes of rats were observed by HE staining, the changes of skin ultrastructure were observed by scanning electron microscopy, and the expression of HIF-2α and H-FABP in rats myocardium was tested by immunohistochemical staining. Results The skin in the electric shock death group and postmortem electric shock group had no significant difference through the naked eye or by HE staining. Under the scanning electron microscope, a largn and decrease H-FABP expression in the myocardium, which may be of forensic significance for the determination of electric shock death and identification of antemortem and postmortem electric shock.

Objective To observe the metabolomics changes of serum after skin incision of rats and to determine the wound age of skin incision. Methods A rat skin incision model was established, 21 SD rats were divided into 1 h, 2 h, 4 h, 8 h, 16 h, 24 h after skin incision groups and the control group, then blood was taken from rats in the experimental groups at the corresponding time points after injury, and taken from the control group directly. Gas chromatography-mass spectrometry （GC-MS） technology was used to detect serum metabolites and screen marker metabolites, then orthogonal partial least square-discriminant analysis （OPLS-DA） model was used to establish a regression model for the relationship between marker metabolite content and wound age to determine wound age of skin. Results GC-MS was used to detect the serum collected, and 21 marker metabolites were obtained through initial screening, and 4 marker metabolites were further analyzed and screened using multivariate statistical analysis methods. There was no correspondence between the change rule of the serum content and wound age, therefore it cannot be used directly to determine wound age.