Thermal Effect and Mechanism Analysis of Flame-Retardant Modified Polymer Electrolyte for Lithium-Ion Battery.

In recent years, the prosperous electric vehicle industry has contributed to the rapid development of lithium-ion batteries. However, the increase in the energy density of lithium-ion batteries has also created more pressing safety concerns. The emergence of a new flame-retardant material with the additive ethoxy (pentafluoro) cyclotriphosphazene can ameliorate the performance of lithium-ion batteries while ensuring their safety. The present study proposes a new polymer composite flame-retardant electrolyte and adopts differential scanning calorimetry (DSC) and accelerating rate calorimetry to investigate its thermal effect. The study found that the heating rate is positively correlated with the onset temperature, peak temperature, and endset temperature of the endothermic peak. The flame-retardant modified polymer electrolyte for new lithium-ion batteries has better thermal stability than traditional lithium-ion battery electrolytes. Three non-isothermal methods (Kissinger; Kissinger-Akahira-Sunose; and Flynn-Wall-Ozawa) were also used to calculate the kinetic parameters based on the DSC experimental data. The apparent activation energy results of the three non-isothermal methods were averaged as 54.16 kJ/mol. The research results can provide valuable references for the selection and preparation of flame-retardant additives in lithium-ion batteries.

Thermal Stability Analysis of Lithium-Ion Battery Electrolytes Based on Lithium Bis(trifluoromethanesulfonyl)imide-Lithium Difluoro(oxalato)Borate Dual-Salt.

Lithium-ion batteries with conventional LiPF6 carbonate electrolytes are prone to failure at high temperature. In this work, the thermal stability of a dual-salt electrolyte of lithium bis(trifluoromethanesulfonyl)imide (LiTFSI) and lithium difluoro(oxalato)borate (LiODFB) in carbonate solvents was analyzed by accelerated rate calorimetry (ARC) and differential scanning calorimetry (DSC). LiTFSI-LiODFB dual-salt carbonate electrolyte decomposed when the temperature exceeded 138.5 °C in the DSC test and decomposed at 271.0 °C in the ARC test. The former is the onset decomposition temperature of the solvents in the electrolyte, and the latter is the LiTFSI-LiODFB dual salts. Flynn-Wall-Ozawa, Starink, and autocatalytic models were applied to determine pyrolysis kinetic parameters. The average apparent activation energy of the dual-salt electrolyte was 53.25 kJ/mol. According to the various model fitting, the thermal decomposition process of the dual-salt electrolyte followed the autocatalytic model. The results showed that the LiTFSI-LiODFB dual-salt electrolyte is significantly better than the LiPF6 electrolyte in terms of thermal stability.

A survey of ventilation strategies during cardiopulmonary resuscitation.

BACKGROUND: Many controversies still exist regarding ventilator parameters during cardiopulmonary resuscitation (CPR). This study aimed to investigate the CPR ventilation strategies currently being used among physicians in Chinese tertiary hospitals. METHODS: A survey was conducted among the cardiac arrest team physicians of 500 tertiary hospitals in China in August, 2018. Surveyed data included physician and hospital information, and preferred ventilation strategy during CPR. RESULTS: A total of 438 (88%) hospitals completed the survey, including hospitals from all 31 mainland Chinese provinces. About 41.1% of respondents chose delayed or no ventilation during CPR, with delayed ventilations all starting within 12 minutes. Of all the respondents who provided ventilation, 83.0% chose to strictly follow the 30:2 strategy, while 17.0% chose ventilations concurrently with uninterrupted compressions. Only 38.3% respondents chose to intubate after initiating CPR, while 61.7% chose to intubate immediately when resuscitation began. During bag-valve-mask ventilation, only 51.4% of respondents delivered a frequency of 10 breaths per minute. In terms of ventilator settings, the majority of respondents chose volume control (VC) mode (75.2%), tidal volume of 6-7 mL/kg (72.1%), PEEP of 0-5 cmH2O (69.9%), and an FiO2 of 100% (66.9%). However, 62.0% of respondents had mistriggers after setting the ventilator, and 51.8% had high pressure alarms. CONCLUSION: There is a great amount of variability in CPR ventilation strategies among cardiac arrest team physicians in Chinese tertiary hospitals. Guidelines are needed with specific recommendations on ventilation during CPR.

[The timing of infusion of hypertonic saline to exert protective effect on intestinal barrier function in the rabbit with intestinal ischemia/reperfusion injury].

OBJECTIVE: To study the timing of infusion of hypertonic saline solution (HTS) to exert its protective effect on intestinal barrier function in rabbits with intestinal ischemia/reperfusion (I/R) injury. METHODS: Seventy-two rabbits were randomly divided into four groups (each n=18): sham operation group, I/R group, HTS pretreatment group and HTS delayed treatment group. The intestinal I/R models were produced by blocking the superior mesenteric artery (SMA) for 1 hour followed by release of the SMA. 7.5% HTS (6 ml/kg) was infused in HTS pretreatment group 5 minutes before release of SMA, and HTS was infused in delayed treatment group 2 hours after reperfusion and finished in 5 minutes. Levels of D-lactic acid (D-Lac), lipopolysaccharide (LPS), tumor necrosis factor-α (TNF-α), interleukin-10 (IL-10) were determined before ischemia and 2, 4, 6 hours after reperfusion. The levels of malonaldehyde (MDA), superoxide dismutase (SOD), myeloperoxidase (MPO) in intestinal tissues of 8 rabbits in each group were measured at 6 hours after reperfusion. Meanwhile the intestinal morphological changes were observed, and the Chin score, which reflected the degree of injury to intestinal mucosa was calculated. RESULTS: Compared with sham operation group, D-Lac, LPS, TNF-α and IL-10 in I/R group were significantly increased from 2 hours after reperfusion (D-Lac: 18.91 ± 3.46 mg/L vs. 3.92 ± 0.61 mg/L, LPS: 869 ± 85 EU/L vs. 422 ± 27 EU/L, TNF-α: 23.80 ± 4.22 µg/L vs. 3.65 ± 0.51µg/L, IL-10: 8.90 ± 2.75 µg/L vs. 2.53 ± 0.80 µg/L, all P<0.05); MDA, MPO and Chiu score were significantly increased (MDA: 398 ± 28 nmol/mg vs. 173 ± 20 nmol/mg, MPO: 465 ± 52 mU/mg vs. 183 ± 25 mU/mg, Chiu score: 4.36 ± 0.52 vs. 0.38 ± 0.22, all P<0.05), while SOD decreased significantly (35 ± 9 U/mg vs. 52 ± 8 U/mg, P<0.05). Compared with I/R group, the levels of D-Lac, LPS, TNF-α, MDA, MPO and Chiu score in HTS pretreatment group were lower (D-Lac: 11.45 ± 0.92 mg/L vs. 18.91 ± 3.46 mg/L, LPS: 455 ± 114 EU/L vs. 869 ± 85 EU/L, TNF-α: 10.32 ± 2.11 µg/L vs. 23.80 ± 4.22 µg/L, MDA: 221 ± 21 nmol/mg vs. 398 ± 28 nmol/mg, MPO: 271 ± 20 mU/mg vs. 465 ± 52 mU/mg, Chiu score: 1.69 ± 0.24 vs. 4.36 ± 0.52, all P<0.05), while IL-10 and SOD were significantly increased (IL-10: 14.54 ± 2.02 µg/L vs. 8.90 ± 2.75 µg/L, SOD: 90 ± 14 U/mg vs. 35 ± 9 U/mg, both P<0.05). The levels of the above indexes in HTS delayed treatment group were similar to I/R group, and the effect was lower than that in HTS pretreatment group. CONCLUSIONS: HTS had the protective effect on intestine suffering from I/R injury. But the protective effect was time dependent, and early treatment shows protective effect.

Modified shock index and mortality rate of emergency patients.

BACKGROUND: This study aimed to determine whether modified shock index (MSI) is associated with mortality that is superior to heart rate, blood pressure, or the shock index (SI) in emergency patients. METHODS: A retrospective database review was performed on 22 161 patients who presented to Peking Union Medical College Hospital Emergency Department and received intravenous fluids from January 1 to December 31, 2009. We gathered data of the patients on age, gender, vital signs, levels of consciousness, presenting complaints, and SI and MSI were calculated for all patients. RESULTS: Multivariate regression analysis was performed to determine the correlation between risk factors and outcome. There is a significant correlation between emergency patient mortality rate and patient's vital signs obtained at the triage desk (HR>120 beats/min, systolic BP<90 mmHg, diastolic BP<60 mmHg). MSI is a stronger predictor of emergency patient mortality compared to heart rate and blood pressure alone, whereas SI does not have a significant correlation with emergency patient mortality rate. CONCLUSION: MSI is a clinically significant predictor of mortality in emergency patients. It may be better than using heart rate and blood pressure alone. SI is not significantly correlated with the mortality rate of the emergency patient.

Role of corticotrophin releasing hormone in cerebral infarction-related gastrointestinal barrier dysfunction.

BACKGROUND: Corticotrophin releasing hormone (CRH) is believed to mediate stress-induced behaviors, implying a broader, integrative role for the hormone in the psychological stress response, and studies on CRH in physical stress are few. This study was undertaken to investigate whether CRH plays an important role in cerebral infarction-related gastrointestinal barrier dysfunction. METHODS: Thirty male Wistar rats were randomly divided into a pseudo-operation group (group C, n=10), a cerebral infarction group (group I, n=10), and a cerebral infarction + ic α-helical-CRH (9-41) group (group Aic, n=10). Urine samples were collected to determine the levels of epinephrine, norepinephrine, cortisol, and sucrose. At 24 hours after establishment of the models, blood samples were taken to determine the activity of diamine oxidase (DAO) and the concentration of D-lactic acid (D-lac). The stomach was taken to determine gastric Guth score, and the hypothalamus was also taken to determine tissue CRH protein expression using Western blotting. RESULTS: The hypothalamus CRH protein, the indicators of stress, the plasma DAO activity and plasma D-lac, urine sucrose exertion and gastric Guth score in group I were higher than those in groups Aic and C. CONCLUSIONS: After cerebral infarction, CRH in the hypothalamus was increased, the hypothalamic-pituitary-adrenal axis and the sympathetic nervous system were activated, gastrointestinal permeability was increased, and gastrointestinal barrier function was destroyed. CRH receptor antagonist alleviated the gastrointestinal barrier function.

[Apoptosis of gastric mucosa and gastric barrier dysfunction in acute ischemic stroke].

OBJECTIVE: To evaluate the role of gastric mucosa apoptosis in the stress of ischemic stroke, and to discuss the relationship between gastric mucosa apoptosis and gastric barrier. METHODS: Ten dogs were artificially made ischemic stroke by operation (IS group), and another 10 shamly-operated dogs were served as control group. Sucrose permeability were measured after the operation. All dogs were sacrificed 24 hours after operation to measure the gastric mucosal apoptosis index, gastric gross classification, and histological score. RESULTS: The gastric mucosal apoptosis index in the IS group were significantly higher than in the control group (14.83 +/- 4.41 vs. 5.60 +/- 2.61, P < 0.05). The gastric mucosal apoptosis index were correlated with the sucrose permeability (r = 0. 89, P < 0.05) , gastric gross classification (r = 0. 87, P < 0.05), and histological score (r = 0.92, P < 0.05). CONCLUSIONS: Although ischemic stroke will not cause the obvious damage in the respiratory and circulatory system, it is responsible for the apoptosis of epithelial cell in the gastric mucosa and gastric barrier dysfunction. The apoptosis index is closely correlated with the damage of the function and morphology of the gastric barrier, indicating that the epithelial cell apoptosis acceleration in the gastric mucosa may result in the damage of gastric barrier function.