Quaternary ammonium cationic polymer as a superior bifunctional binder for lithium – sulfur batteries and effects of counter anion

Bifunctional polymer binders featured with both strong binding and superior polysulfide trapping properties are highly desired for the fabrication of sulfur cathodes with suppressed polysulfide shuttling in Li–S batteries. In this paper, we have explored the potential of a quaternary ammonium cationic polymer, polydiallyldimethylammonium (PDADMA-X; X = T, B, P, and Cl) with different counter anions (TFSI–, BF4−, PF6−, and Cl−, respectively) as the bifunctional binder. We have also revealed the dramatic effects of the counter anion on the performance of the cationic polymer binder. PDADMA-X's containing the former three weakly associating anions have been demonstrated to show polysulfide adsorption capability. In particular, PDADMA-T having the largest, least interacting TFSI– anion shows the optimum performance, with strong binding strength and the best polysulfide adsorption capability. Relative to commercial PVDF and PDADMA-X's of other counter anions, it offers sulfur cathodes with lowered polarization, higher discharge capacity, significantly better capacity retention, and improved cycling stability. With its convenient synthesis from commercially available PDADMA-Cl, cationic PDADMA-T having the TFSI– anion is a promising bifunctioal binder for sulfur cathodes in practical Li-sulfur batteries

Enhanced electrical and thermal conductivities of 3D-SiC(rGO, G x ) PDCs based on polycarbosilane-vinyltriethoxysilane-graphene oxide (PCS-VTES-GO) precursor containing graphene fillers

Abstract(#br)Lightweight 3D-SiC(rGO, G x ) PDCs were fabricated from polycarbosilane-vinyltriethoxysilane-graphene oxide (PCS-VTES-GO) precursor added by different amounts of graphene fillers via direct cold molding and pyrolysis at 1400 °C in an easy manner. Results reveal that SiC(rGO, G x ) PDCs consist of β-SiC nanocrystals homogeneously embedded within amorphous SiO x C y /C free , and graphene is well compatible with SiO x C y /C free for void-free bonded interface, efficiently delaying decomposition of SiO x C y phase into β-SiC. The nanocomposite structure provides an ingenious strategy for constructing complexes with good integrity, high ceramic yield, excellent thermal stability, high electrical and thermal conductivities. This improvement is primarily attributed to the presence of graphene with considerably increasing electric-charge carriers and wider phonon-channel. Such 3D-SiC(rGO, G 20% ) PDCs possess satisfying hardness (12.02 GPa), high electrical conductivity (23.82 S cm −1 ) and thermal conductivity (7.47 W m −1 K −1 ), which make them attractive candidates for microelectromechanical systems (MEMS) devices, energy storage/conversion systems and high precision components, etc

Methylprednisolone as Adjunct to Endovascular Thrombectomy for Large-Vessel Occlusion Stroke

Importance It is uncertain whether intravenous methylprednisolone improves outcomes for patients with acute ischemic stroke due to large-vessel occlusion (LVO) undergoing endovascular thrombectomy. Objective To assess the efficacy and adverse events of adjunctive intravenous low-dose methylprednisolone to endovascular thrombectomy for acute ischemic stroke secondary to LVO. Design, Setting, and Participants This investigator-initiated, randomized, double-blind, placebo-controlled trial was implemented at 82 hospitals in China, enrolling 1680 patients with stroke and proximal intracranial LVO presenting within 24 hours of time last known to be well. Recruitment took place between February 9, 2022, and June 30, 2023, with a final follow-up on September 30, 2023.InterventionsEligible patients were randomly assigned to intravenous methylprednisolone (n = 839) at 2 mg/kg/d or placebo (n = 841) for 3 days adjunctive to endovascular thrombectomy. Main Outcomes and Measures The primary efficacy outcome was disability level at 90 days as measured by the overall distribution of the modified Rankin Scale scores (range, 0 [no symptoms] to 6 [death]). The primary safety outcomes included mortality at 90 days and the incidence of symptomatic intracranial hemorrhage within 48 hours. Results Among 1680 patients randomized (median age, 69 years; 727 female [43.3%]), 1673 (99.6%) completed the trial. The median 90-day modified Rankin Scale score was 3 (IQR, 1-5) in the methylprednisolone group vs 3 (IQR, 1-6) in the placebo group (adjusted generalized odds ratio for a lower level of disability, 1.10 [95% CI, 0.96-1.25]; P = .17). In the methylprednisolone group, there was a lower mortality rate (23.2% vs 28.5%; adjusted risk ratio, 0.84 [95% CI, 0.71-0.98]; P = .03) and a lower rate of symptomatic intracranial hemorrhage (8.6% vs 11.7%; adjusted risk ratio, 0.74 [95% CI, 0.55-0.99]; P = .04) compared with placebo. Conclusions and Relevance Among patients with acute ischemic stroke due to LVO undergoing endovascular thrombectomy, adjunctive methylprednisolone added to endovascular thrombectomy did not significantly improve the degree of overall disability.Trial RegistrationChiCTR.org.cn Identifier: ChiCTR210005172

Nontrivial Effects of “Trivial” Parameters on the Performance of Lithium–Sulfur Batteries

A robust lithium-sulfur (Li–S) battery is constituted by a wide range of optimized fundamental parameters (e.g., amount of electrolyte, electrolyte additive, sulfur loading density, and the size of sulfur particles). In this paper, some other often-neglected “trivial” parameters (including assembly pressure of the coil cells, thickness of spring/lithium foil in coin cells, sheet number of separator, and cut-off voltage) of Li–S batteries have been demonstrated to show pronounced effects on the battery performance. Our results indicate that the coin cell assembly pressure and sheet number of the separator play the important roles in suppressing polysulfide shuttling over battery cycling, which improves significantly the cycling life of Li–S batteries. The thickness of springs/lithium foils also affects the battery performance greatly. When switching the cut-off voltage of 1.5–3.0 V to narrower ones (1.7–2.5 V or 1.8–2.6 V), the cycling life of batteries at 0.2 C can be further enhanced to >300 cycles while with no drastic polysulfide shuttling. Adjusting these trivial parameters can thus synergistically improve the cycling performance of Li–S batteries

Prognostic Value of the Red Cell Distribution Width in Patients with Sepsis-Induced Acute Respiratory Distress Syndrome: A Retrospective Cohort Study

Objective. The prognostic value of the red cell distribution width (RDW) in patients with sepsis-induced acute respiratory distress syndrome (ARDS) is still elusive. This study is aimed at determining whether RDW is a prognostic indicator of sepsis-induced ARDS. Methods. This retrospective cohort study included 1161 patients with sepsis-induced ARDS. The datasets were acquired from the Medical Information Mart for Intensive Care III database. The locally weighted scatter-plot smoothing technique, Cox regression, Kaplan-Meier estimator, and subgroup analysis were carried out to evaluate the association between RDW and 90-day mortality. Results. The RDW and mortality had a roughly linear increasing relationship. The Cox regression model results were as follows: for level 2 (14.5%<RDW<16.2%), hazard ratio HR=1.35, 95% confidence interval CI=1.03–1.77, and for level 3 (RDW≥16.2%), HR=2.07, 95% CI=1.59–2.69. The following results were obtained when RDW was treated as a continuous variable: HR=1.11, 95%CI=1.06–1.15. The P values of the interaction between the RDW and covariates were greater than 0.05. Conclusion. RDW is a new independent prognostic marker for patients with sepsis-induced ARDS

Mussel-Inspired Surface Functionalization of AEM for Simultaneously Improved Monovalent Anion Selectivity and Antibacterial Property

A facile membrane surface modification process for improving permselectivity and antimicrobial property was proposed. A polydopamine (PDA) coating was firstly fabricated on pristine anion exchange membrane (AEM), followed by in situ reduction of Ag without adding any extra reductant. Finally, 2,5-diaminobenzene sulfonic acid (DSA) was grafted onto PDA layer via Michael addition reaction. The as-prepared AEM exhibited improved permselectivity (from 0.60 to 1.43) and effective inhibition of bacterial growth. In addition, the result of the long-term (90-h continuous electrodialysis) test expressed the excellent durability of the modified layer on membrane surface, because the concentration of Cl- and SO₄²- in diluted chamber fluctuated ~0.024 and 0.030 mol·L-1 with no distinct decline. The method described in this work makes the full use of multifunctional PDA layer (polymer-like coating, in situ reduction and post-organic reaction), and a rational design of functional AEM was established for better practical application.status: publishe

Highly conductive anion exchange membranes with low water uptake and performance evaluation in electrodialysis

© 2018 Elsevier B.V. The present work reports the preparation of a series of novel highly durable imidazolium-decorated anion exchange membranes (AEMs), with 3D network structure, via ultraviolet crosslinking reaction between 1-vinylimidazole and 1,6-hexanedithiol. AEM modified with trimethylamine (TMA) groups (no crosslinking, 45.7%) showed a significantly reduced water uptake within a range of 14.4–23.6% at 80 °C. Due to relatively good alkali-resistant of imidazolium groups and the compact structure stemmed from crosslinking network, the optimum cross-linked AEM (BPPO-Im 0.3) can retard the degradation and exhibits superior alkaline stability in 1.0 M NaOH at 60 °C for over 15 days, compared with TMA modified AEM. In ED application, BPPO-Im 0.3 AEM has a higher NaCl removal ratio of 77.82% than that of commercial AEM-Type II (74.13%) within 3 h experimental time. Accordingly, it shows higher current efficiency (67.43%) and lower energy consumption (1.94 kWh kg−1 NaCl), compared to commercial one (62.83%; 2.05 kWh kg−1). The facile fabrication process and the better-performance are suggestive of that BPPO-Im 0.3 is potentially applicable in ED.status: publishe

Mussel-Inspired Surface Functionalization of AEM for Simultaneously Improved Monovalent Anion Selectivity and Antibacterial Property

A facile membrane surface modification process for improving permselectivity and antimicrobial property was proposed. A polydopamine (PDA) coating was firstly fabricated on pristine anion exchange membrane (AEM), followed by in situ reduction of Ag without adding any extra reductant. Finally, 2,5-diaminobenzene sulfonic acid (DSA) was grafted onto PDA layer via Michael addition reaction. The as-prepared AEM exhibited improved permselectivity (from 0.60 to 1.43) and effective inhibition of bacterial growth. In addition, the result of the long-term (90-h continuous electrodialysis) test expressed the excellent durability of the modified layer on membrane surface, because the concentration of Cl&minus; and SO42&minus; in diluted chamber fluctuated ~0.024 and 0.030 mol&middot;L-1 with no distinct decline. The method described in this work makes the full use of multifunctional PDA layer (polymer-like coating, in situ reduction and post-organic reaction), and a rational design of functional AEM was established for better practical application

Effect of Tetramethylpyrazine on Neuroplasticity after Transient Focal Cerebral Ischemia Reperfusion in Rats

Tetramethylpyrazine (TMP) has been widely used in ischemic stroke in China. The regulation of neuroplasticity may underlie the recovery of some neurological functions in ischemic stroke. Middle cerebral artery occlusion (MCAO) model was established in this study. Rats were divided into three groups: sham group, model group, and TMP group. The neurological function was evaluated using modified neurological severity score (mNSS). Following the neurological function test, expression of synaptophysin (SYP) and growth-associated protein 43 (GAP-43) were analyzed through immunohistochemistry at 3 d, 7 d, 14 d, and 28 d after MCAO. Finally, the synaptic structural plasticity was investigated using transmission electron microscopy (TEM). The TMP group showed better neurological function comparing to the model group. SYP levels increased gradually in ischemic penumbra (IP) in the model group and could be enhanced by TMP treatment at 7 d, 14 d, and 28 d, whereas GAP-43 levels increased from 3 d to 7 d and thereafter decreased gradually from 14 d to 28 d in the model group, which showed no significant improvement in the TMP group. The results of TEM showed a flatter synaptic interface, a thinner postsynaptic density (PSD), and a wider synaptic cleft in the model group, and the first two alterations could be ameliorated by TMP. Then, a Pearson’s correlation test revealed mNSS markedly correlated with SYP and synaptic ultrastructures. Taken together, TMP is capable of promoting functional outcome after ischemic stroke, and the mechanisms may be partially associated with regulation of neuroplasticity