Objective To explore the growing development and community succession of main sarcos-aphagous insects on pig carcasses in summer indoor and outdoor environment in Shenzhen area and to estimate the postmortem interval (PMI). Methods From early May to August in 2013, in Forensic Med-ical Examination Center of Shenzhen Public Security Bureau, the main insect species and the decomposi-tion process were observed in two adult pig carcasses of simulative indoor and outdoor environment. The different decomposition stages and the community succession of insects were recorded. Results The indoor and outdoor pig carcasses showed skeleton 412.5 and 325 hours after death, respectively. The main species of flies on pig carcasses were Chrysomya megacephala, Chrysomya rufifacies and Chrysomya chani. The main species of beetles were Crecphilus maxillosus, Necrobia ruficollis, Saprinus splendens and Dermestes maculatu. The dominant species of flies in the outdoor pig carcasses obviously produced the second generations due to the effect of mass rainfall, nor in the indoor pig carcasses. Conclusion There are regular patterns on the community succession of insects on pig carcasses in summer indoor and out-door environment in Shenzhen area. The activity patterns of seven typical insects and their larva show important value for estimating PMI.

Objective To detect the changes of microbial community functional diversity of corpses with different postmortem interval(PMI)and to evaluate forensic application value for estimating PMI. Methods The cultivation of microbial community from the anal swabs of aSusscrofaand a human corpse placed in field environment from 0 to 240 h after death was performed using the Biolog-Eco Mi-croplate and the variations of the absorbance values were also monitored. Combined with the technology of forensic pathology and flies succession, the metabolic characteristics and changes of microbial commu-nity on the decomposed corpse under natural environment were also observed.Results The diversity of microbial metabolism function was found to be negatively correlated with the number of maggots in the corpses. The freezing processing had the greatest impact on average well color development value at 0 h and the impact almost disappeared after 48 h. The diversity of microbial metabolism of the samples be-came relatively unstable after 192 h. The principal component analysis showed that 31 carbon sources could be consolidated for 5 principal components(accumulative contribution ratio >90%). The carbon source tsquare-analysis showed thatN-acetyl-D-glucosamine andL-serine were the dominant carbon sources for estimating the PMI(0=240 h)of theSusscrofaand human corpse.Conclusion The Biolog-Eco method can be used to reveal the metabolic differences of the carbon resources utilization of the microbial community on the corpses during 0-240 h after death, which could provide a new basis for estimating the PMI.

Objective:To establish the normal reference range of the ratio of fetal umbilical venous flow rate to umbilical artery pulsatility index (VAI).Methods:A total of 816 normal fetuses underwent prenatal examination and delivery were randomly selected from October 2018 to December 2020 in Maternal and Child Health Hospital of Guangxi Zhuang Autonomous Region. Fetal weight was obtained by measuring fetal biparietal diameter, head circumference, abdominal circumference, and femoral length.Umbilical venous flow (Quv) was measured. Umbilical artery pulsatility index (UA-PI) was obtained in the free segment of amniotic fluid. Quv was standardized according to fetal size to calculate the umbilical venous flow rate (nQuv) and VAI. The association between Quv, nQuv, UA-PI, VAI and the fetal gestational week were analyzed using correlation analysis. VAI was presented as ± s, the upper limit of 95% reference value and the lower limit of 5% reference value were taken as the standards of VAI increase and decrease, respectively. Twenty-six fetuses whose VAI were lower than limit of 5% and 20 fetuse whose VAI were than limit of 95% were chosed as the case group. Results:①Fetal Quv was positively correlated with gestational week ( r=0.893, P<0.001), nQuv and UA-PI were negatively correlated with gestational week ( r=-0.552, -0.827; all P<0.001), and VAI had no significant correlation with gestational week ( r=0.000, P=0.758); ②The mean, standard deviation, lower 5% reference value, and upper 95% reference value of VAI were 195.81, 55.61, 105.95, and 293.33, respectively; ③In the cases with abnormal VAI, 26 fetuses with reduced VAI, of whom there were 16 cases of maternal hypertension, and 13 cases complicated by severe preeclampsia; 1 case with 40 turns of umbilical cord torsion, 3 cases of stillbirth, 16 cases of preterm delivery, 19 cases of low neonatal birth body weight, 4 cases of 1-min Apgar score ≤7, 6 cases of umbilical artery blood pH<7.2, and 1 case without abnormalities in fetus during pregnancy and follow-up newborn. Among the 20 fetuses with increased VAI, there were 10 cases of fetal severe thalassemia, 2 cases of thalassemia, 1 case of sacrococcygeal teratoma, 1 case of portal venous shunt, 3 cases of placental chorioangioma, and 3 cases without abnormalities in fetus during pregnancy and follow-up newborn. Conclusions:The measurement and calculation of fetal VAI is simple and easy to perform. As a comprehensive index, fetal VAI remains constant in mid and late pregnancy, facilitates the follow-up of abnormal fetuses, and has potential clinical application.