From Squaric Acid Amides (SQAs) to Quinoxaline-Based SQAs─Evolution of a Redox-Active Cathode Material for Organic Polymer Batteries.

The search for new redox-active organic materials (ROMs) is essential for the development of sustainable energy-storage solutions. In this study, we present a new class of cyclobuta[b]quinoxaline-1,2-diones or squaric acid quinoxalines (SQXs) as highly promising candidates for ROMs featuring exceptional stability and high redox potentials. While simple 1,2- and 1,3-squaric acid amides (SQAs), initially reported by Hünig and coworkers decades ago, turned out to exhibit low stability in their radical cation oxidation states, we demonstrate that embedding the nitrogen atoms into a quinoxaline heterocycle leads to robust two-electron SQX redox systems. A series of SQX compounds, as well as their corresponding radical cations, were prepared and fully characterized, including EPR spectroscopy, UV-vis spectroscopy, and X-ray diffraction. Based on the promising electrochemical properties and high stability of the new ROM, we developed SQX-functionalized polymers and investigated their physical and electrochemical properties for energy-storage applications. These polymers showed remarkable thermal stability well above 200 °C with reversible redox properties and potentials of about 3.6 V vs Li+/Li. By testing the galvanostatic cycling performance in half-cells with lithium-metal counter electrodes, a styrene-based polymer with SQX redox side groups showed stable cycling for single-electron oxidation for more than 100 cycles. These findings render this new class of redox-active polymers as highly promising materials for future energy-storage applications.

Locally Concentrated Ionic Liquid Electrolytes Enabling Low-Temperature Lithium Metal Batteries.

Lithium metal is a promising anode material for next-generation high-energy-density batteries but suffers from low stripping/plating Coulombic efficiency and dendritic growth particularly at sub-zero temperatures. Herein, a poorly-flammable, locally concentrated ionic liquid electrolyte with a wide liquidus range extending well below 0 °C is proposed for low-temperature lithium metal batteries. Its all-anion Li+ solvation and phase-nano-segregation solution structure are sustained at low temperatures, which, together with a solid electrolyte interphase rich in inorganic compounds, enable dendrite-free operation of lithium metal anodes at -20 °C and 0.5 mA cm-2 , with a Coulombic efficiency of 98.9 %. As a result, lithium metal batteries coupling thin lithium metal anodes (4 mAh cm-2 ) and high-loading LiNi0.8 Co0.15 Al0.05 O2 cathodes (10 mg cm-2 ) retain 70 % of the initial capacity after 100 cycles at -20 °C. These results, as a proof of concept, demonstrate the applicability of locally concentrated ionic liquid electrolytes for low-temperature lithium metal batteries.

Association between short-term changes in serum magnesium and in-hospital mortality following acute myocardial infarction: a cohort study based on the MIMIC database.

The association between short-term changes in serum magnesium level and risk of in-hospital mortality was investigated in patients with acute myocardial infarction (AMI). In this retrospective cohort study, data of 2,716 patients with AMI were extracted from the Medical Information Mart for Intensive Care (MIMIC-III and MIMIC-IV) database for 2001-2012. Univariate and multivariate Cox proportional hazards models were used to explore the association between serum magnesium level and short-term change and in-hospital mortality in patients with AMI. In addition, subgroups according to age, gender, Sequential Organ Failure Assessment (SOFA) score, and Simplified Acute Physiology Score (SAPS-II) were also analysed. In total, 504 (18.6%) patients died in hospital. After adjusting for covariates, all AMI patients with high magnesium levels at ICU admission (HR=1.03, 95% CI: 0.83-1.27) or 48 hours after ICU admission (all p<0.05), or those demonstrating a change in magnesium level within the first 48 hours of ICU stay (all p<0.05) were shown to have a high risk of in-hospital mortality. Moreover, this correlation was retained irrespective of age, gender, SOFA score, and SAPS-II (all p<0.05). Serum magnesium levels at different time points after ICU admission and change in serum magnesium level during the first 48 hours were associated with in-hospital mortality in patients with AMI, indicating that clinical attention should be paid to short-term changes in serum magnesium levels regarding treatment adjustment, which may further reduce the risk of mortality.

Biphenyl-Bridged Organosilica as a Precursor for Mesoporous Silicon Oxycarbide and Its Application in Lithium and Sodium Ion Batteries.

Silicon oxycarbides (SiOC) are an interesting alternative to state-of-the-art lithium battery anode materials, such as graphite, due to potentially higher capacities and rate capabilities. Recently, it was also shown that this class of materials shows great prospects towards sodium ion batteries. Yet, bulk SiOCs are still severely restricted with regard to their electrochemical performance. In the course of this work, a novel and facile strategy towards the synthesis of mesoporous and carbon-rich SiOC will be presented. To achieve this goal, 4,4'-bis(triethoxysilyl)-1,1'-biphenyl was sol-gel processed in the presence of the triblock copolymer Pluronic P123. After the removal of the surfactant using Soxhlet extraction the organosilica material was subsequently carbonized under an inert gas atmosphere at 1000 °C. The resulting black powder was able to maintain all structural features and the porosity of the initial organosilica precursor making it an interesting candidate as an anode material for both sodium and lithium ion batteries. To get a detailed insight into the electrochemical properties of the novel material in the respective battery systems, electrodes from the nanostructured SiOC were studied in half-cells with galvanostatic charge/discharge measurements. It will be shown that nanostructuring of SiOC is a viable strategy in order to outperform commercially applied competitors.

High-density lipoprotein ameliorates palmitic acid-induced lipotoxicity and oxidative dysfunction in H9c2 cardiomyoblast cells via ROS suppression.

BACKGROUND: High levels circulating saturated fatty acids are associated with diabetes, obesity and hyperlipidemia. In heart, the accumulation of saturated fatty acids has been determined to play a role in the development of heart failure and diabetic cardiomyopathy. High-density lipoprotein (HDL) has been reported to possess key atheroprotective biological properties, including cellular cholesterol efflux capacity, anti-oxidative and anti-inflammatory activities. However, the underlying mechanisms are still largely unknown. Therefore, the aim of the present study is to test whether HDL could protect palmitic acid (PA)-induced cardiomyocyte injury and explore the possible mechanisms. RESULTS: H9c2 cells were pretreated with HDL (50-100 µg/ml) for 2 h followed by PA (0.5 mM) for indicated time period. Our results showed that HDL inhibited PA-induced cell death in a dose-dependent manner. Moreover, HDL rescued PA-induced ROS generation and the phosphorylation of JNK which in turn activated NF-κB-mediated inflammatory proteins expressions. We also found that PA impaired the balance of BCL2 family proteins, destabilized mitochondrial membrane potential, and triggered subsequent cytochrome c release into the cytosol and activation of caspase 3. These detrimental effects were ameliorated by HDL treatment. CONCLUSION: PA-induced ROS accumulation and results in cardiomyocyte apoptosis and inflammation. However, HDL attenuated PA-induced lipotoxicity and oxidative dysfunction via ROS suppression. These results may provide insight into a possible molecular mechanism underlying HDL suppression of the free fatty acid-induced cardiomyocyte apoptosis.