A Nomogram Model for Predicting Type-2 Myocardial Infarction Induced by Acute Upper Gastrointestinal Bleeding

Objective To examine the independent risk factors of type-2 myocardial infarction(T2MI)elicited by acute upper gastrointestinal bleeding(AUGIB),and to establish a nomogram model for the prediction of AUGIB-induced T2MI.Methods A nomogram model was established on the basis of a retrospective study that involved 533 patients who suffered from AUGIB in the Department of Critical Care Medicine(CCM)or Emergency Intensive Care Unit(EICU)of Renmin Hospital of Wuhan University,Wuhan,China,from January 2017 to December 2020.The predictive accuracy and discriminative power of the nomogram were initially evaluated by internal validation,which involved drawing the receiver operating characteristic(ROC)curve,calculating the area under the curve(AUC),plotting the calibration curve derived from 1000 resampled bootstrap data sets,and computing the root mean square error(RMSE).The predictive ability of the nomogram was further validated through the prospective and multicenter study conducted by the investigators,which enrolled 240 AUGIB patients[including 88 cases from Renmin Hospital of Wuhan University,73 cases from Qilu Hospital of Shandong University(Qingdao),and 79 cases from Northern Jiangsu People’s Hospital)],who were admitted to the Department of CCM or EICU,from February 2021 to July 2021.Results Among the 533 patients in the training cohort,78(14.6%)patients were assigned to the T2MI group and 455(85.4%)patients were assigned to the non-T2MI group.The multivariate analysis revealed that age>65,hemorrhagic shock,cerebral stroke,heart failure,chronic kidney disease,increased blood urea nitrogen,decreased hematocrit,and elevated D-Dimer were independent risk factors for AUGIB-induced T2MI.All these factors were incorporated into the nomogram model.The AUC for the nomogram for predicting T2MI was 0.829(95%CI,0.783-0.875)in the internal validation cohort and 0.848(95%CI,0.794-0.902)in the external validation cohort.The calibration curve for the risk of T2MI exhibited good consistency between the prediction by the nomogram and the actual clinical observation in both the internal validation(RMSE=0.016)and external validation(RMSE=0.020).Conclusion The nomogram was proven to be a useful tool for the risk stratification of T2MI in AUGIB patients,and is helpful for the early identification of AUGIB patients who are prone to T2MI for early intervention,especially in emergency departments and intensive care units.

Secondary electron emission yield from vertical graphene nanosheets by helicon plasma deposition

The secondary electron emission yields of materials depend on the geometries of their surface structures.In this paper,a method of depositing vertical graphene nanosheet(VGN)on the surface of the material is proposed,and the secondary electron emission(SEE)characteristics for the VGN structure are studied.The COMSOL simulation and the scanning electron microscope(SEM)image analysis are carried out to study the secondary electron yield(SEY).The effect of aspect ratio and packing density of VGN on SEY under normal incident condition are studied.The results show that the VGN structure has a good effect on suppressing SEE.

Synthesis of SiC/graphene nanosheet composites by helicon wave plasma

We report an approach to the rapid, one-step, preparation of a variety of wide-bandgap silicon carbide/graphene nanosheet(Si C/GNSs) composites by using a high-density helicon wave plasma(HWP) source. The microstructure and morphology of the Si C/GNSs are characterized by using scanning electron microscopy(SEM), Raman spectroscopy, x-ray diffraction(XRD), x-ray photoelectron spectroscopy(XPS), and fluorescence(PL). The nucleation mechanism and the growth model are discussed. The existence of Si C and graphene structure are confirmed by XRD and Raman spectra.The electron excitation temperature is calculated by the intensity ratio method of optical emission spectroscopy. The main peak in the PL test is observed at 420 nm, with a corresponding bandgap of 2.95 e V that indicates the potential for broad application in blue light emission and ultraviolet light emission, field electron emission, and display devices.