Effect of ionic liquids on the microstructure and combustion performance of Shengli lignite.

To ensure the safe transportation and efficient utilisation of lignite, it is important to inhibit its spontaneous combustion. In this study, Shengli lignite (SL+) was used as the research object and ionic liquids (ILs) were used to pretreat the lignite to investigate their effect on the combustion performance of lignite. On this basis, the relationship between the structure and combustion performance of lignite with different structures (heat treatment, oxidation) after ILs treatment was investigated. Results indicated that the combustion of lignite treated with ILs shifted towards higher temperatures. The most pronounced effect was observed in coal samples treated with [BMIM]Cl (1-butyl-3-methylimidazolium chloride), with the maximum combustion rate corresponding to a temperature increase of approximately 57 °C compared to that of the untreated lignite. For the heat-treated lignite, the temperature corresponding to the maximum combustion rate was approximately 38 °C higher than that of the untreated lignite. After [BMIM]Cl treatment, the combustion performance of the heat-treated lignite changed very slightly. In contrast, for oxidised lignite, the temperature corresponding to the maximum combustion rate decreased by approximately 54 °C compared with that of the untreated lignite and increased by approximately 135 °C after treatment with [BMIM]Cl. The characterisation results show that the content of aliphatic hydrogen and oxygen-containing functional groups decreased in the heat-treated lignite, while the content of hydroxyl and carboxyl groups increased in the oxidised lignite. The microstructure of the heat-treated lignite after [BMIM]Cl treatment changed slightly. In contrast, in the oxidised lignite after [BMIM]Cl treatment, the content of hydroxyl and carboxyl groups decreased, whereas the content of ether (C-O-) structures increased. The increased content of ether (C-O-) structures improved the stability of the coal samples. It is believed that the inhibition of lignite combustion is mainly attributed to the high stability of the ether (C-O-) structures. The kinetic analysis demonstrated that the ILs treatment increased the activation energy of lignite combustion.

The incidence and risk factors of perioperative cardiac complications in noncardiac major surgery in high-altitude areas: A prospective trial in Tibet autonomous region, China.

Background: The risk of perioperative cardiac complications (PCCs) in patients living in high-altitude areas may increase with more adverse clinical outcomes due to the special geographical environment, which has not yet been studied. We aimed to determine the incidence and analyze risk factors for PCCs in adult patients undergoing major noncardiac surgery in the Tibet Autonomous Region. Methods: This prospective cohort study enrolled resident patients from high-altitude areas receiving major noncardiac surgery in Tibet Autonomous Region People's Hospital in China. Perioperative clinical data were collected, and the patients were followed up until 30 days after surgery. The primary outcome was PCCs during the operation and within 30 days after the surgery. Logistic regression was used to build the prediction models for PCCs. A receiver operating characteristic (ROC) curve was used to evaluate the discrimination. A prognostic nomogram was constructed to generate a numerical probability of PCCs for patients undergoing noncardiac surgery in high-altitude areas. Results: Among the 196 patients living in high-altitude areas involved in this study, 33 (16.8%) suffered PCCs perioperatively and within 30 days after surgery. Eight clinical factors were identified in the prediction model, including older age (P = 0.028), extremely high altitude above 4,000 m (P = 0.442), preoperative metabolic equivalent (MET) < 4 (P = 0.153), history of angina within 6 months (P = 0.037), history of great vascular disease (P = 0.073), increased preoperative high sensitivity C-reactive protein (hs-CRP) (P = 0.072), intraoperative hypoxemia (P = 0.025) and operation time >3 h (P = 0.043). The area under the curve (AUC) was 0.766 (95% confidence interval: 0.785-0.697). The score calculated from the prognostic nomogram predicted the risk of PCCs in high-altitude areas. Conclusion: The incidence of PCCs in resident patients living in high-altitude areas who underwent noncardiac surgery was high, and the risk factors included older age, high altitude above 4,000 m, preoperative MET < 4, history of angina within 6 months, history of great vascular disease, increased preoperative hs-CRP, intraoperative hypoxemia, and operation time >3 h. The prognostic nomogram of this study could help to assess the PCCs for patients in high-attitude areas undergoing noncardiac surgery. Clinical Trial Registration: ClinicalTrials.gov ID: NCT04819698.

Preoperative Transthoracic Echocardiography Predicts Cardiac Complications in Elderly Patients with Coronary Artery Disease Undergoing Noncardiac Surgery.

Purpose: Guidelines have not recommended routine transthoracic echocardiography (TTE) for elderly patients prior to noncardiac surgery. We aimed to evaluate the significance of preoperative TTE to predict perioperative cardiac complications (PCCs) for elderly patients with coronary artery disease (CAD) undergoing noncardiac surgery. Patients and methods: We retrospectively reviewed 2204 patients over 65 years of age with CAD who underwent TTE before intermediate- or high-risk noncardiac surgery in a teaching hospital in China between September 2013 and August 2019. The revised cardiac risk index (RCRI) was assessed. PCCs comprised acute coronary syndrome, heart failure, new-onset severe arrhythmia, nonfatal cardiac arrest, and cardiac death. Logistic regression was used to build the prediction model for PCCs. Discrimination was evaluated using receiver operating characteristic curves, and a nomogram of the predictive model was constructed. Results: PCCs occurred in 189 (8.6%) patients. Multivariable analysis showed that eight clinical risk factors (age, history of myocardial infarction, insulin therapy for diabetes, New York Heart Association classification, preoperative serum creatinine, preoperative electrocardiogram ST-T abnormality and pathological Q wave, and American Society of Anesthesiologists classification) and five TTE parameters (left atrial anteroposterior dimension, left ventricular ejection fraction, left ventricular diastolic dysfunction, pulmonary hypertension, and regional ventricular wall motion abnormality) were associated with PCCs. The receiver operating characteristic curve for the clinical plus TTE model provided better discrimination for PCCs compared with the RCRI model (area under the curve: 0.731 vs 0.564; P < 0.001) and the clinical model (area under the curve: 0.731 vs 0.697, P = 0.001), respectively. The clinical plus TTE model was presented as a prognostic nomogram. Conclusion: Preoperative TTE may help predict PCCs in elderly patients with CAD undergoing noncardiac surgery, and the prognostic nomogram from this study appeared to be useful for the assessment of perioperative cardiac risk.