-
Hess Albrechtsen posted an update 6 months, 4 weeks ago
These measurements reveal an important shift in the nature of OC, with implications for biogeochemical cycling within estuaries and for regional environmental changes.Overcharge is a hazardous abuse condition that has dominant influences on cell performance and safety. This work, for the first time, comprehensively investigates the impact of different overcharge degrees on degradation and thermal runaway behavior of lithium-ion batteries. The results indicate that single overcharge has little influence on cell capacity, while it severely degrades thermal stability. Triptolide Degradation mechanisms are investigated by utilizing the incremental capacity-differential voltage and relaxation voltage analyses. During the slight overcharge process, the conductivity loss and the loss of lithium inventory always occur; the loss of active material starts happening only when the cell is overcharged to a certain degree. Lithium plating is the major cause for the loss of lithium inventory, and an interesting phenomenon that the arrival time of the dV/dt peak decreases linearly with the increase of the overcharge degree is found. The cells with different degrees of overcharge exhibit a similar behavior during adiabatic thermal runaway. Meanwhile, the relationship between sudden voltage drop and thermal runaway is further established. More importantly, the characteristic temperature of thermal runaway, especially the self-heating temperature (T1), decreases severely along with overcharging, which means that a slight overcharge severely decreases the cell thermal stability. Further, post-mortem analysis is conducted to investigate the degradation mechanisms. The mechanism of the side reactions caused by a slight overcharge on the degradation performance and thermal runaway characteristics is revealed.Accelerating the redox reaction of polysulfides via catalysis is an effective way to suppress the shuttling effect in lithium-sulfur (Li-S) cells. However, recent studies have mainly focused on the singular function of the catalyst, i.e., either oxidation or reduction of polysulfides. As such, the goal of rapid cycling of sulfur species remains to be highly desired. Herein, a Pt-carbide composite as a bifunctional catalyst was developed to simultaneously accelerate both the reduction of soluble polysulfides and the oxidation of insoluble Li2S/Li2S2. Typically, a Pt-NbC composite was synthesized by growing Pt nanoparticles on the surface of NbC, and the resultant intimate interface in the hybrid is a key component for the bifunctional catalysis. During the reduction process, polysulfides could be grabbed on the surface of NbC via strong adsorption, and then these trapped polysulfides could be catalytically converted by Pt nanoparticles. During the oxidation process, both NbC and Pt exhibited catalytic activities for the dissolution of Li2S. This process could lead to the renewal of the surface of the catalyst. By combining the sulfur cathode with a Pt-NbC-CNT (Pt-NbC anchored on a carbon nanotube)-coated separator, the cell was able to demonstrate a high initial capacity of 1382 mAh g-1 at a current density of 0.2C. Furthermore, the cell was able to achieve an exceptional rate capability of 795 mAh g-1 at 5C, and it was also able to show significantly inhibited self-discharge behavior. Thus, this work explores the catalyst design and the mechanism of a bifunctional catalyst for the performance enhancement in Li-S cells.Glass-ceramic sulfide solid electrolytes like Li7P3S11 are practicable propellants for safe and high-performance all-solid-state lithium-sulfur batteries (ASSLSBs); however, the stability and conductivity issues remain unsatisfactory. Herein, we propose a congener substitution strategy to optimize Li7P3S11 as Li7P2.9Sb0.1S10.75O0.25 via chemical bond and structure regulation. Specifically, Li7P2.9Sb0.1S10.75O0.25 is obtained by a Sb2O5 dopant to achieve partial Sb/P and O/S substitution. Benefiting from the strengthened oxysulfide structural unit of POS33- and P2OS64- with bridging oxygen atoms and a distorted lattice configuration of the Sb-S tetrahedron, the Li7P2.9Sb0.1S10.75O0.25 electrolyte exhibits prominent chemical stability and high ionic conductivity. Besides the improved air stability, the ionic conductivity of Li7P2.9Sb0.1S10.75O0.25 could reach 1.61 × 10-3 S cm-1 at room temperature with a wide electrochemical window of up to 5 V (vs Li/Li+), as well as good stability against Li and Li-In alloy anodes. Consequently, the ASSLSB with the Li7P2.9Sb0.1S10.75O0.25 electrolyte shows high discharge capacities of 1374.4 mAh g-1 (0.05C, 50th cycle) at room temperature and 1365.4 mAh g-1 (0.1C, 100th cycle) at 60 °C. The battery also presents remarkable rate performance (1158.3 mAh g-1 at 1C) and high Coulombic efficiency (>99.8%). This work provides a feasible technical route for fabricating ASSLSBs.Multiple biological barriers in solid tumors severely restrict the penetration of nanomedicines, which is a main cause for therapeutic failure in traditional tumor treatment. Here, a tumor-specific nanogenerator of peroxynitrite (ONOO-), prepared by loading cisplatin and sodium nitroprusside into poly(d,l-lactide-co-glycolide) polymersomes, was designed to improve drug delivery and enhance tumor chemotherapy. After a cascade of nicotinamide adenine dinucleotide phosphate oxidases catalysis and glutathione reduction, the nanogenerator, namely, PMCS, could selectively induce the generation of ONOO- in tumor. The generated ONOO- could not only strengthen vascular permeability significantly but also improve the accumulation and penetration of PMCS in tumor by activating matrix metalloproteinases-mediated degradation of extracellular matrix. Along with endocytosis, PMCS released cisplatin to induce tumor cell apoptosis. Moreover, free cisplatin liberated from dead cells infected neighboring tumor cells quickly via ONOO–mediated up-regulated copper transporter 1, further amplifying chemotherapeutic efficacy. This study advances ONOO- as a potent modality to address the main issues of therapeutic delivery, including but not limited to chemotherapy.Pantetheinase (also known as Vanin-1) is highly expressed in the liver, kidneys, and intestine and is closely associated with a number of diseases. Vanin-1 can hydrolyze pantetheine to pantothenic acid (vitamin B5) and cysteamine and participate in the synthesis of glutathione (GSH). GSH is highly expressed in tumor cells and plays a major role in the resistance of tumor cells to cisplatin. Therefore, we urgently need a method to monitor the activity level of Vanin-1 in tumor cells and tissues and elucidate the relationship between the role of Vanin-1 in GSH synthesis and tumor resistance. Herein, we report a Cy-Pa fluorescent probe for imaging Vanin-1 in cells and in vivo that can qualitatively and quantitatively detect the fluctuation of Vanin-1 concentrations in HepG2 and HepG2/DDP cells or tumor tissues of tumor-bearing mice. This probe shows excellent potential in in situ real-time monitoring of endogenous Vanin-1. Moreover, we proved that Vanin-1 can inhibit GSH synthesis using the probe. When the Vanin-1 inhibitor RR6 was used in combination with cisplatin, HepG2 and HepG2/DDP cells showed increased resistance to cisplatin, while the therapeutic efficiency of cisplatin was reduced in HepG2 and HepG2/DDP xenografts.
Please follow & like us :)
All content contained on CatsWannaBeCats.Com, unless otherwise acknowledged,is the property of CatsWannaBeCats.Com and subject to copyright.