Generative learning facilitated discovery of high-entropy ceramic dielectrics for capacitive energy storage.

Dielectric capacitors offer great potential for advanced electronics due to their high power densities, but their energy density still needs to be further improved. High-entropy strategy has emerged as an effective method for improving energy storage performance, however, discovering new high-entropy systems within a high-dimensional composition space is a daunting challenge for traditional trial-and-error experiments. Here, based on phase-field simulations and limited experimental data, we propose a generative learning approach to accelerate the discovery of high-entropy dielectrics in a practically infinite exploration space of over 1011 combinations. By encoding-decoding latent space regularities to facilitate data sampling and forward inference, we employ inverse design to screen out the most promising combinations via a ranking strategy. Through only 5 sets of targeted experiments, we successfully obtain a Bi(Mg0.5Ti0.5)O3-based high-entropy dielectric film with a significantly improved energy density of 156 J cm-3 at an electric field of 5104 kV cm-1, surpassing the pristine film by more than eight-fold. This work introduces an effective and innovative avenue for designing high-entropy dielectrics with drastically reduced experimental cycles, which could be also extended to expedite the design of other multicomponent material systems with desired properties.

Programming Polarity Heterogeneity of Energy Storage Dielectrics by Bidirectional Intelligent Design.

Dielectric capacitors, characterized by ultra-high power densities, are considered as fundamental energy storage components in electronic and electrical systems. However, synergistically improving energy densities and efficiencies remains a daunting challenge. Understanding the role of polarity heterogeneity at the nanoscale in determining polarization response is crucial to the domain engineering of high-performance dielectrics. Here, a bidirectional design with phase-field simulation and machine learning is performed to forward reveal the structure-property relationship and reversely optimize polarity heterogeneity to improve energy storage performance. Taking BiFeO3-based dielectrics as typical systems, this work establishes the mapping diagrams of energy density and efficiency dependence on the volume fraction, size and configuration of polar regions. Assisted by CatBoost and Wolf Pack algorithms, this work analyzes the contributions of geometric factors and intrinsic features and find that nanopillar-like polar regions show great potential in achieving both high polarization intensity and fast dipole switching. Finally, a maximal energy density of 188 J cm-3 with efficiency above 95% at 8 MV cm-1 is obtained in BiFeO3-Al2O3 systems. This work provides a general method to study the influence of local polar heterogeneity on polarization behaviors and proposes effective strategies to enhance energy storage performance by tuning polarity heterogeneity.

Texture Engineering Modulating Electromechanical Breakdown in Multilayer Ceramic Capacitors.

Understanding the electromechanical breakdown mechanisms of polycrystalline ceramics is critical to texture engineering for high-energy-density dielectric ceramics. Here, an electromechanical breakdown model is developed to fundamentally understand the electrostrictive effect on the breakdown behavior of textured ceramics. Taking the Na0.5 Bi0.5 TiO3 -Sr0.7 Bi0.2 TiO3 ceramic as an example, it is found that the breakdown process significantly depends on the local electric/strain energy distributions in polycrystalline ceramics, and reasonable texture design could greatly alleviate electromechanical breakdown. Then, high-throughput simulations are performed to establish the mapping relationship between the breakdown strength and different intrinsic/extrinsic variables. Finally, machine learning is conducted on the database from the high-throughput simulations to obtain the mathematical expression for semi-quantitatively predicting the breakdown strength, based on which some basic principles of texture design are proposed. The present work provides a computational understanding of the electromechanical breakdown behavior in textured ceramics and is expected to stimulate more theoretical and experimental efforts in designing textured ceramics with reliable electromechanical performances.

Adiponectin Attenuates Streptozotocin-Induced Tau Hyperphosphorylation and Cognitive Deficits by Rescuing PI3K/Akt/GSK-3ß Pathway.

Clinical studies have demonstrated that decreased adiponectin is associated with the development of Type 2 diabetes mellitus (T2DM) and Alzheimer's disease (AD). We focused on determining the neuroprotective effect offered by adiponectin against streptozotocin-induced brain damage in ICV-STZ rat model. We found that adiponectin supplements significantly restored the cognitive deficits in ICV-STZ rat model including shorter escape latency, more crossing times and increased time spent in the target quadrant. Adiponectin supplements also increased number of dendritic branches and mushroom percentage. In addition, adiponectin supplements attenuated tau hyperphosphorylation at multiple AD-related sites through activation of protein Ser9-phosphorylated glycogen synthase kinase-3ß (Ser9-GSK-3ß) with increased the Akt and PI3K activity. Our data suggest that adiponectin supplements have neuroprotective effects on the ICV-STZ rat model, which may be mediated by the activation of the PI3K/Akt/GSK-3ß signaling pathway.

[Effects of tempol on white matter lesions and cognitive impairment in a rat model of chronic cerebral hypoperfusion].

OBJECTIVE: To assess the neuroprotective effect of Tempol, an antioxidant acting as a superoxide dismutase mimic, on white matter lesions and cognitive impairment in rats with chronic cerebral hypoperfusion. METHODS: Chronic cerebral ischemia was induced by permanent occlusion of bilateral common carotid arteries (2-VO) in male Wistar rats. The animals were divided into sham operation, saline-treated, Tempol (8 mg/kg) and Tempol (30 mg/kg) groups (n = 15 each). Performance of Morris water maze task and Western blot for myelin basic protein (MBP), amyloid precursor protein (APP) and 4-hydroxy-2-nonenal (HNE) modified proteins were analyzed at 6 weeks post-hypoperfusion. RESULTS: Tempol reduced the escape latency of Morris water maze post-hypoperfusion in comparison with the saline-treated rats (P < 0.05). The mean relative optical density of MBP in the white matter was significantly higher in Tempol (8 mg/kg) group (0.82 ± 0.17) and Tempol (30 mg/kg) group (0.91 ± 0.15) than saline-treated group (0.44 ± 0.13, all P < 0.01). The mean relative optical density of APP in white matter was significantly lower in Tempol (8 mg/kg) group (0.55 ± 0.13) and Tempol (30 mg/kg) group (0.46 ± 0.15) than saline-treated group (0.96 ± 0.19, all P < 0.01). The mean relative optical density of HNE-modified protein in white matter was significantly lower in Tempol (8 mg/kg) group (0.20 ± 0.035) and Tempol (30 mg/kg) group (0.18 ± 0.031) than saline-treated group (0.29 ± 0.039, all P < 0.01). CONCLUSION: Tempol ameliorates cognitive impairment by preventing white matter lesions induced by chronic cerebral hypoperfusion in rats. And it may protect white matter lesions in hypoperfused rats through reducing the formation of lipid peroxidation.

Dielectric properties of lead-free BZT-KNN perovskite ceramics for energy storage.

Lead-free (1-x)Ba(Zr0.15Ti0.85)O3-x(K0.5Na0.5)NbO3 ; x=0-0.05) (BZT-KNN) perovskite ceramics, a materials with potential applications for energy storage, are investigated. The samples are prepared by a solid-state reaction method. Powder X-ray diffraction (XRD) and scanning electron microscopy (SEM) are used to study the microstructure of the samples. Their dielectric properties and impedance spectra are reported as functions of temperature and frequency. The addition of 1 mol % (K0.5Na0.5)NbO3 to Ba(Zr0.15Ti0.85)O3 improves the dielectric constant and enhances its diffuseness in a wide temperature range. The small amount of (K0.5Na0.5)NbO3 is found to markedly affect the microstructure of the Ba(Zr0.15Ti0.85)O3 ceramic (grain size and other characteristics) without changing the phase or crystal symmetry. In addition, we report that fine substructures in the grains, so-called sheet structures, are responsible for the dielectric properties (both diffuseness and dielectric constant) of (1-x)Ba(Zr0.15Ti0.85)O3-x(K0.5Na0.5)NbO3 (x=0-0.03; especially x=0.01) ceramics.

Zn2+ mediates ischemia-induced impairment of the ubiquitin-proteasome system in the rat hippocampus.

Abstract Deposition of ubiquitinated protein aggregates is a hallmark of neurodegeneration in both acute neural injuries, such as stroke, and chronic conditions, such as Parkinson's disease, but the underlying mechanisms are poorly understood. In the present study, we examined the role of Zn2+ in ischemia-induced impairment of the ubiquitin-proteasome system in the CA1 region of rat hippocampus after transient global ischemia. We found that scavenging endogenous Zn2+ reduced ischemia-induced ubiquitin conjugation and free ubiquitin depletion. Furthermore, exposure to zinc chloride increased ubiquitination and inhibited proteasomal enzyme activity in cultured hippocampal neurons in a concentration- and time-dependent manner. Further studies of the underlying mechanisms showed that Zn(2+)-induced ubiquitination required p38 activation. These findings indicate that alterations in Zn2+ homeostasis impair the protein degradation pathway.

[IR study of the hardening and maturation of glass ionomer cement].

The set reaction of glass ionomer cement has been investigated by means of IR spectra. It has been found that the band intensity around 1413 cm(-1) due to the vibration of polyacrylate salt increased with aging, and the shoulder band at 950 cm(-1) due to the stretching vibration of Si-OH still appeared during the periods studied. The results are consistent with that of mechanical determination of compressive strength, which suggested that the crosslink density increase resulting from the slow diffusion of Ca2+ and Al3+ is responsible for compressive strength increasing with aging, and forming and maturing of interface layer comprising of silica gel also have a significant effect on the properties of glass ionomer cements.

Altered expression of MAP-2, GAP-43, and synaptophysin in the hippocampus of rats with chronic cerebral hypoperfusion correlates with cognitive impairment.

Chronic cerebral hypoperfusion causes cognitive impairment, but the underlying molecular mechanism is not well understood. We used permanent occlusion of bilateral common carotid arteries (2-VO) to induce chronic cerebral hypoperfusion in male Wistar rats. Cognitive impairment and the expression patterns of MAP-2, GAP-43, and synaptophysin were examined. We found that both learning capacity and memory were gradually impaired in the rats with chronic cerebral hypoperfusion concomitant with increased duration of 2-VO treatment. Four weeks of 2-VO treatment resulted in down-regulation of synaptophysin expression at the protein levels, and a further decrease was observed at 10-20 weeks, although mRNA levels remained the same. Ten weeks of 2-VO treatment lead to down-regulation of MAP-2 expression at both the mRNA and protein levels with a further decrease at 20 weeks. Interestingly, GAP-43 mRNA was significantly up-regulated by 2-VO treatment, although the protein levels were not altered. Therefore, the cognitive impairment caused by chronic cerebral hypoperfusion may be partially explained by reduced expression of synaptophysin and MAP-2 at the protein level. The reduction in MAP-2 expression may be attributed to the inhibition of transcription, while the reduction in synaptophysin expression might be due to the inhibition of translation. Up-regulation of GAP-43 mRNA in the rat hippocampus with 2-VO treatment suggests that a compensatory mechanism may antagonize ischemic challenges.