[Melatonin alleviates autophagy in cortical neurons of neonatal rats with hypoxic- ischemic brain damage via the PI3K/AKT pathway]. / è¤ªé»‘ç´ é€šè¿‡PI3K/AKTé€šè·¯å‡è½»ç¼ºæ°§ç¼ºè¡€æ€§è„‘æŸä¼¤æ–°ç”Ÿå¤§é¼ å¤§è„‘çš®å±‚ç¥žç»ç»†èƒžè‡ªå™¬çš„ç ”ç©¶.

OBJECTIVES: To observe the effects of melatonin on autophagy in cortical neurons of neonatal rats with hypoxic-ischemic brain damage (HIBD) and to explore its mechanisms via the PI3K/AKT signaling pathway, aiming to provide a basis for the clinical application of melatonin. METHODS: Seven-day-old Sprague-Dawley neonatal rats were randomly divided into a sham operation group, an HIBD group, and a melatonin group (n=9 each). The neonatal rat HIBD model was established using the classic Rice-Vannucci method. Neuronal morphology in the neonatal rat cerebral cortex was observed with hematoxylin-eosin staining and Nissl staining. Autophagy-related protein levels of microtubule-associated protein 1 light chain 3 (LC3) and Beclin-1 were detected by immunofluorescence staining and Western blot analysis. Phosphorylated phosphoinositide 3-kinase (p-PI3K) and phosphorylated protein kinase B (p-AKT) protein expression levels were measured by immunohistochemistry and Western blot. The correlation between autophagy and the PI3K pathway in the melatonin group and the HIBD group was analyzed using Pearson correlation analysis. RESULTS: Twenty-four hours post-modeling, neurons in the sham operation group displayed normal size and orderly arrangement. In contrast, neurons in the HIBD group showed swelling and disorderly arrangement, while those in the melatonin group had relatively normal morphology and more orderly arrangement. Nissl bodies were normal in the sham operation group but distorted in the HIBD group; however, they remained relatively intact in the melatonin group. The average fluorescence intensity of LC3 and Beclin-1 was higher in the HIBD group compared to the sham operation group, but was reduced in the melatonin group compared to the HIBD group (P<0.05). The number of p-PI3K+ and p-AKT+ cells decreased in the HIBD group compared to the sham operation group but increased in the melatonin group compared to the HIBD group (P<0.05). LC3 and Beclin-1 protein expression levels were higher, and p-PI3K and p-AKT levels were lower in the HIBD group compared to the sham operation group (P<0.05); however, in the melatonin group, LC3 and Beclin-1 levels decreased, and p-PI3K and p-AKT increased compared to the HIBD group (P<0.05). The correlation analysis results showed that the difference of the mean fluorescence intensity of LC3 and Beclin-1 protein in the injured cerebral cortex between the melatonin and HIBD groups was negatively correlated with the difference of the number of p-PI3K+ and p-AKT+ cells between the two groups (P<0.05). CONCLUSIONS: Melatonin can inhibit excessive autophagy in cortical neurons of neonatal rats with HIBD, thereby alleviating HIBD. This mechanism is associated with the PI3K/AKT pathway.

Ultrathin MXene Nanosheets Decorated with TiO2 Quantum Dots as an Efficient Sulfur Host toward Fast and Stable Li-S Batteries.

Being conductive and flexible, 2D transition metal nitrides and carbides (MXenes) can serve in Li-S batteries as sulfur hosts to increase the conductivity and alleviate the volume expansion. However, the surface functional groups, such as OH and F, weaken the ability of bare MXenes in the chemisorption of polysulfides. Besides, they create numerous hydrogen bonds which make MXenes liable to restack, resulting in substantial loss of active area and, thus, inaccessibility of ions and electrolyte. Herein, a facile, one-step strategy is developed for the growth of TiO2 quantum dots (QDs) on ultrathin MXene (Ti3 C2 Tx ) nanosheets by cetyltrimethylammonium bromide-assisted solvothermal synthesis. These QDs act as spacers to isolate the MXene nanosheets from restacking, and preserve their 2D geometry which guarantees larger electrode-electrolyte contact area and higher sulfur loading. The stronger adsorption energy of polysulfides with TiO2 (than with Ti3 C2 Tx ), as proven by density functional theory calculations, is essential for better on-site polysulfide retention. The ultrathin nature and protected conductivity ensure rapid ion and electron diffusion, and the excellent flexibility maintains high mechanical integrity. In result, the TiO2 QDs@MXene/S cathode exhibits significantly improved long-term cyclability and rate capability, disclosing a new opportunity toward fast and stable Li-S batteries.

A hierarchically porous TiO2@C membrane with oxygen vacancies: a novel platform for enhancing the catalytic conversion of polysulfides.

In cases involving high levels of sulfur loading or high levels of current discharge, constructing sulfur composite cathodes via traditional coating preparation processes is an unsuitable way to overcome intractable problems relating to cathodes for use in lithium-sulfur batteries, such as poor conductivity, severe volume expansion, and the detrimental shuttle effect. Herein, a novel three-dimensional self-supported TiO2@C membrane with hierarchical interlinked porosity and oxygen vacancies was prepared via a phase-inversion method to act as a sulfur host. The procured TiO2-x@C membrane facilitates the infiltration of electrolyte, provides fast lithium-ion and electron transport channels and abundant sulfur loading sites, and shows superb structural buffering against the large volume changes during the conversion process between sulfur and lithium sulfide. More importantly, the introduction of oxygen vacancies not only enhances the conductivity of the original TiO2, but it also improves the corresponding adsorption abilities toward polysulfides and the subsequent transformation dynamics. Therefore, the TiO2-x@C membrane can significantly inhibit the polysulfide shuttle effect through polar chemisorption and conversion catalysis. Based on the above superiorities, the TiO2-x@C/S membrane electrode exhibits an impressive lifespan of more than 500 cycles at 2 C with a prominent ultimate specific discharge capacity of 715.2 mA h g-1.

MXene-supported Co3O4 quantum dots for superior lithium storage and oxygen evolution activities.

A novel hybrid, composed of Co3O4 quantum dots supported on Ti3C2Tx (MXene) nanosheets, exhibits a strong synergetic effect, and shows superior lithium storage (capacity = 766.5 mA h g-1 at 2 A g-1 after 400 cycles) and oxygen evolution (overpotential = 340 mV at 10 mA cm-2) activities.

Smartly Designed Hierarchical MnO2 @Fe3 O4 /CNT Hybrid Films as Binder-free Anodes for Superior Lithium Storage.

Nowadays, the development of advanced anode materials is highly desirable for the increasing demand for high-performance lithium-ion batteries (LIBs). Nanostructured MnO2 has received utmost attention due to high theoretical capacity (1230 mA h g-1 ), abundant resources, environmental benignity, and shortened electron and ion diffusion paths. Unfortunately, poor electronic conductivity and strong aggregation inclination of MnO2 nanostructures result in disappointing electrochemical performances, which restrict their practical application as sole institute. Here, we propose smartly designed MnO2 @Fe3 O4 /CNT hybrid films, in which MnO2 nanosheets, Fe3 O4 nanoparticles and CNTs are hierarchically assembled in a unique stage of nanosheets-nanoparticles-nanotubes. The resulting MnO2 @Fe3 O4 /CNT hybrid films can be directly used as anodes without any polymer binders, and exhibit significant synergistic interactions among three components, achieving excellent reversible capacity and rate performance.