RESUMO
Porous carbons prepared using a self-template approach inherit the pore features of template, but they exhibit almost no evenly dispersed mesopores, which is significant for diffusion-limited applications. Herein, N-doped hierarchically porous carbons (NHPCs) with uniform mesopores are prepared using a self-template method. The spherical single-molecule micelle of polystyrene-b-poly(4-vinyl pyridine) (PS-b-P4VP) is turned into a Zn2+-coordinated PS-b-P4VP micelle (CPM) by coordination of Zn2+ with the P4VP shell. Then, the self-template of the CPM is carbonized into a hollow carbon nanosphere. During carbonization, the PS core is decomposed to generate the central mesopore, whereas the Zn2+-coordinated P4VP shell is transformed into a carbonaceous shell. These even hollow carbon nanospheres aggregate to form uniformly mesoporous carbon lumps. Simultaneously, the coordinated Zn2+ of the CPM is reduced to metal zinc at high temperatures and then it is evaporated, thus creating numerous micropores in the carbonaceous shell. These NHPCs with uniform mesopores display a high specific surface area. As a demonstration in diffusion-limited applications, their catalytic performances for the oxygen reduction reaction (ORR) are investigated. Strikingly, NHPCs exhibit outstanding catalytic performances for the ORR. This self-template method paves a facile approach for preparing mesoporous carbons with high performances.
RESUMO
Background: Whether heart rate (HR) fluctuation after admission has an impact on the outcomes of critically ill myocardial infarction (MI) patients in intensive care unit remains unknown. Methods: A total of 2,031 MI patients were enrolled from the Medical Information Mart for Intensive Care (MIMIC-III) database. HR fluctuation was calculated as the maximum HR minus the minimum HR in the initial 24 h after admission. Participants were divided into 3 groups, namely, low HR fluctuation [<30 beats per minute (bpm)], medium HR fluctuation (30-49 bpm), and high HR fluctuation (≥ 50 bpm). The main outcomes were 30-day and 1-year mortality. Cox regression and restricted cubic spline model were used. Results: Each 10-bpm increase in HR fluctuation was associated with a higher risk of 30-day mortality and 1-year mortality, with adjusted hazard ratios of 1.122 (95% CI, 1.083-1.162) and 1.107 (95% CI, 1.074-1.140), respectively. Compared with the low HR fluctuation group, the high HR fluctuation group suffered a significantly higher risk of mortality after adjustment, with hazard ratios of 2.156 (95% CI, 1.483-3.134) for 30-day mortality and 1.796 (95% CI, 1.354-2.381) for 1-year mortality. A typical J-type curve was observed in restricted cubic splines for the association between HR fluctuation and 30-day or 1-year mortality of MI patients, with the lowest risk on the HR fluctuation of 30 bpm. Sensitivity analyses emphasized the robustness of our results. Conclusions: This retrospective cohort study revealed an independent positive association between HR fluctuation and 30-day and 1-year mortality in critically ill MI patients, which warrants further investigation.
RESUMO
OBJECTIVES: We aimed to develop and validate a prognostic nomogram and evaluate the discrimination of the nomogram model in order to improve the prediction of 30-day survival of critically ill myocardial infarction (MI) patients. DESIGN: A retrospective cohort study. SETTING: Data were collected from the Medical Information Mart for Intensive Care (MIMIC)-III database, consisting of critically ill participants between 2001 and 2012 in the USA. PARTICIPANTS: A total of 2031 adult critically ill patients with MI were enrolled from the MIMIC-III database. PRIMARY AND SECONDARY OUTCOME: Thirty-day survival. RESULTS: Independent prognostic factors, including age, heart rate, white blood cell count, blood urea nitrogen and bicarbonate, were identified by Cox regression model and used in the nomogram. Good agreement between the prediction and observation was indicated by the calibration curve for 30-day survival. The nomogram exhibited reasonably accurate discrimination (area under the receiver operating characteristic curve, 0.765, 95% CI, 0.716 to 0.814) and calibration (C-index, 0.758, 95% CI, 0.712 to 0.804) in the validation cohort. Decision curve analysis demonstrated that the nomogram was clinically beneficial. Additionally, participants could be classified into two risk groups by the nomogram, and the 30-day survival probability was significantly different between them (p<0.001). CONCLUSION: This five-factor nomogram can achieve a reasonable degree of accuracy to predict 30-day survival in critically ill MI patients and might be helpful for risk stratification and decision-making for MI patients.