Kerosene is an ideal endothermic hydrocarbon. Its pyrolysis plays a significant role in the thermal protection for high-speed aircraft. Before it reacts, kerosene experiences thermal decomposition in the heat exchanger and produces cracked products. Thus, to use cracked kerosene instead of pure kerosene, knowledge of their ignition properties is needed. In this study, ignition delay times of cracked kerosene/air and kerosene/air were measured in a heated shock tube at temperatures of 657-1333 K, an equivalence ratio of 1.0, and pressures of 1.01 × 10 5 -10.10 × 10 5 Pa. Ignition delay time was defined as the time interval between the arrival of the reflected shock and the occurrence of the steepest rise of excited-state CH species (CH*) emission at the sidewall measurement location. Pure helium was used as the driver gas for high-temperature measurements in which test times needed to be shorter than 1.5 ms, and tailored mixtures of He/Ar were used when test times could reach up to 15 ms. Arrhenius-type formulas for the relationship between ignition delay time and ignition conditions (temperature and pressure) were obtained by correlating the measured high-temperature data of both fuels. The results reveal that the ignition delay times of both fuels are close, and an increase in the pressure or temperature causes a decrease in the ignition delay time in the high-temperature region (> 1000 K). Both fuels exhibit similar high-temperature ignition delay properties, because they have close pressure exponents (cracked kerosene: τign∝P −0.85 ; kerosene: τign∝P −0.83 ) and global activation energies (cracked kerosene: Ea = 143.37 kJmol −1 ; kerosene: Ea = 144.29 kJmol −1 ). However, in the low-temperature region (< 1000 K), ignition delay characteristics are quite different. For cracked kerosene/air, while the decrease in the temperature still results in an increase in the ignition delay time, the negative temperature coefficient (NTC) of ignition delay does not occur, and the low-temperature ignition data still can be correlated by an Arrhenius-type formula with a much smaller global activation energy compared to that at high temperatures. However, for kerosene/air, this NTC phenomenon was observed, and the Arrhenius-type formula fails to correlate its low-temperature ignition data. At temperatures ranging from 830 to 1000 K, the cracked kerosene ignites faster than the kerosene; at temperatures below 830 K, kerosene ignition delay times become much shorter than those of cracked kerosene. Surrogates for cracked kerosene and kerosene are proposed based on the H/C ratio and average molecular weight in order to simulate ignition delay times for cracked kerosene/air and kerosene/air. The simulation results are in fairly good agreement with current experimental data for the two fuels at high temperatures (> 1000 K). However, in the low-temperature NTC region, the results are in very good agreement with kerosene ignition delay data but disagree with cracked kerosene ignition delay data. The comparison between experimental d...

e16140 Background: Gallbladder neuroendocrine neoplasm (GB-NEN) is an extremely rare type of gallbladder neoplasm and the prognosis of patients with GB-NENs varies widely. The focus of this study was to construct and validate a prognostic model of GB-NENs based on the data from a nationwide retrospective multicenter registry cohort. Methods: The Chinese Research Group of Gallbladder Cancer (CRGGC) study is a multicenter retrospective registry cohort study reviewing the electronic medical records from 76 tertiary and secondary hospitals across 28 provinces in China. We assembled patients with GB-NEN diagnosed between 2010 and 2017 in 24 tertiary hospitals from CRGGC study. Influential factors of recurrence free survival (RFS) and overall survival (OS) were identified using Least absolute shrinkage and selection operator (LASSO) regression and Cox predicting model was constructed for predicting RFS and OS. The prognostic model was validated both internally and externally. Performance of the model was assessed by concordance index (C-index) and calibration curves stratified by risk categories. Results: A total of 84 patients with GB-NEN was extracted from CRGGC study, among which 3 were diagnosed with GB-NEN Grade 1, 8 were diagnosed with GB-NEN Grade 2 and 35 with GB-NEN Grade 3. Of the 35 patients with GB-NEN Grade 3, 3 had poorly differentiated small-cell neuroendocrine carcinomas (SC-NECs) and 8 patients had Mixed neuroendocrine–non‐neuroendocrine neoplasms (MiNENs). 53 patients were included in the training group (median survival, 21.1 months; 95% confidence interval (CI), 13.8-37.6 months) and 31 patients in the validation cohort (median survival, 34.3 months; 95% CI, 9.63-58.97months). A Cox predicting model was built, including 5 variables (age, TNM stage, surgery, metastasis at liver, proportion of positive lymph nodes examined). The C-index was 78.1 (95% CI, 63.9-92.3), with a good calibration, and these results were confirmed in the internal validation cohorts. Conclusions: We have built a clinical model for GB-NEN patients and clinical doctors for prognosis prediction based on age, TNM stage, surgery, metastasis at liver, proportion of positive lymph nodes examined which can be easily obtained in one’s case history. It can be used to determine subgroups of patients who may have poorer prognosis and assist individualized and precise treatment for GB-NEN.

e16119 Background: Gallbladder Neuroendocrine Neoplasm (GB-NEN) is an extremely rare type of gallbladder neoplasms and its characteristics and prognosis varies widely. The focus of this study was to analyze and compare the clinical pathological features, surgical treatments and prognosis of patients with GB-NEN between Chinese and American population. Methods: The Chinese Research Group of Gallbladder Cancer (CRGGC) study is a multicenter retrospective registry cohort study reviewing the electronic medical records from 76 tertiary and secondary hospitals across 28 provinces in China. Patients diagnosed with GB-NEN according to the 2019 WHO classification between 2010 and 2017 were assembled from CRGGC study and National Cancer Institute's Surveillance, Epidemiology, and End Results (SEER) database. Chi-square test for categorical variables and the overall survival outcomes were analyzed by the Kaplan–Meier method in the two groups before and after a propensity score matching (PSM) with 1:1 ratio. Results: In this study, we assembled totally 84 patients from CRGGC study and there were 217 patients with GB-NEN diagnosed during the same period from National Cancer Institute's Surveillance, Epidemiology, and End Results (SEER) database. After the PSM using sex, age, American Joint Committee on Cancer stage 7th Edition, liver invasion status and types of surgical treatment, 19 pairs of patients were included. Chinese patients from the CRGGC with GB-NENs presents more liver invasion (c²= 22.621, P = 0.000), higher diagnosed age (c²= 37.313, P = 0.000) and cancer stage (c²= 13.298, P = 0.021) totally than those from the SEER database. Radical surgical treatments were performed in 51(60.714%) and 96(44.240%) patients among patients from the CRGGC study and the SEER database respectively and the surgical treatment model shows a difference between these two groups (c²= 85.729, P = 0.000). Compared with propensity score matched American patients with GB-NENs from SEER database, Chinese patients from the CRGGC study had similar overall survival(c²= 0.480, P = 0.489) instead of longer overall survival than patients from the SEER database before PSM(c²= 6.408, P = 0.011). Conclusions: Chinese and American patients with GB-NEN form the CRGGC study and the SEER database present no difference in overall survival after PSM. However, heterogeneity of pathological features, surgical treatments between those groups of GB-NEN patients prompt that different methods could be referred for the improvement in the survival of GB-NEN patients.