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Polymeric dielectrics have garnered significant interest worldwide due to their excellent comprehensive performance. However, developing polymeric dielectric films with high permittivity (εr) and breakdown strength (Eb) and low dielectric loss (tanδ) presents a huge challenge. In this study, amorphous aluminum oxide (Al2O3, AO) transition interfaces with nanoscale thickness were constructed between titanium oxide (TiO2, TO) nanosheets and polyvinylidene fluoride (PVDF) to manufacture composites (PVDF/TO@AO). TO@AO nanosheets showed favorable dispersion in the polymer-based composites. Improved permittivity, suppressed dielectric loss, and enhanced breakdown strength were achieved by introducing AO coating with intermediate permittivity onto TO nanosheets to build a transition interface. The transition interface efficiently depressed the mobility of the charge carrier and electric conduction of the PVDF/TO@AO composites. As a result, the PVDF-based composite with 1 wt% TO@AO showed superior comprehensive performance, including high εr of ~12.7, low tanδ of ~0.017, and exceptional Eb of ~357 kV/mm. This strategy supplies a novel paradigm for the application of fabricating dielectric films with excellent comprehensive performance. [ABSTRACT FROM AUTHOR]

In the dynamic fields of information science and electronic technology, there is a notable trend towards leveraging carbon materials, favored for their ease of synthesis, biocompatibility, and abundance. This trend is particularly evident in the development of memristors, benefiting from the unique electronic properties of carbon to enhance device performance. This study utilizes sensitized chemical evaporation and spin-coating carbonization techniques to fabricate nickel-cobalt coated carbon composite nanofibers (SC-NCMNTs). Novel polyimide (PI) matrix composite memory devices were fabricated using in situ polymerization technology. Transmission electron microscopy (TEM) and micro-Raman spectroscopy analyses validated the presence of dual interface structures located between the Ni-Co-MWNTs, carbon composite nanofibers, and PI matrix, revealing a significant number of defects within the SC-NCMNTs/PI composite films. Consequently, this results in a tunable charge trap-based ternary resistive switching behavior of the composite memory devices, exhibiting a high ON/OFF current ratio of 104 and a retention time of 2500 s at an operating voltage of less than 3 V. The mechanism of resistive switching is thoroughly elucidated through a comprehensive charge transport model, incorporating molecular orbital energy levels. This study provides valuable insights for the rational design and fabrication of efficient memristors characterized by multilevel resistive switching states. [ABSTRACT FROM AUTHOR]

Polymer matrix composite memristors exhibit exceptional performances, including a straightforward structure, rapid operational speed, high density, good scalability, cost-effectiveness, and superior mechanical flexibility for wearable applications. This study utilizes sensitized chemical evaporation and spin coating carbonization techniques to fabricate composite nanofibers doped with Nickel-Cobalt coated multi-walled carbon nanotubes (SC-NCMTs). A novel polyimide matrix composite memory device was fabricated using in-situ polymerization technology. The transmission electron microscopy (TEM) and micro-Raman spectroscopy analyses validate the presence of dual interfaces structure locating between the Ni-Co-MWNTs, carbon nanofibers and PI matrix and a large number of defects in the SC-NCMTs/PI composite films, resulting in tunable ternary resistive switching behaviors of the composite memory device, exhibiting good ON/OFF current ratio of 104 and a retention time of 2500 s under operating voltages V onset ≤ 3 V. Based on the interface layer distribution and the defects in the composites, different physical models are comprised to investigate the charge transmission mechanism underlying the multilevel resistive switching behaviors. The studies on the impact of tunable multi-interfaces trap structures on multilevel resistive switching could enhance the data storage capabilities of polymer matrix memristors. [ABSTRACT FROM AUTHOR]

Polymer-based energy storage media are widely used in electrical and electronic applications due to their high power density and excellent charge and discharge efficiency. In this paper, thermoplastic polyurethane elastomer (TPU) organic fillers were doped with polyetherimide (PEI) by the solution blending method to prepare PEI composite films with excellent energy storage properties. The effects of different TPU contents on the dielectric properties, leakage current density, and energy storage performance of the composite films were explored. The results showed that the flexible TPU fillers, which could improve the inter-chain interactions and spatial structure of PEI, reduced the chain spacing of the polymer, effectively hindered the input of charge carriers, and mitigated the electric field distortion, thus improving the insulation and dielectric properties of PEI. When the mass fraction of the added TPU elastomer reaches 0.75%, the energy storage density of the composite film reaches 11.51 J/cm3, which is 2.88 J/cm3 higher than that of the pure polyetherimide, while maintaining a high charge/discharge efficiency (87.32%), and the energy storage performance has been significantly improved under an applied electric field strength of 600 MV/m. The results show that the composite film is more efficient than the pure polyetherimide, and the energy storage performance has been significantly improved. [ABSTRACT FROM AUTHOR]

Introduction T follicular helper (Tfh) cells are a subset of specialized effector [CD4.sup.+] T cells mediating B cell selection, proliferation, and differentiation in germinal centers (GCs) (1). Aberrant activation of [...], T follicular helper (Tfh) cells are indispensable for the formation of germinal center (GC) reactions, whereas T follicular regulatory (Tfr) cells inhibit Tfh-mediated GC responses. Aberrant activation of Tfh cells contributes substantially to the pathogenesis of autoimmune diseases, such as systemic lupus erythematosus (SLE). Nonetheless, the molecular mechanisms mitigating excessive Tfh cell differentiation are not fully understood. Herein we demonstrate that the adenovirus E4 promoter-binding protein (E4BP4) mediates a feedback loop and acts as a transcriptional brake to inhibit Tfh cell differentiation. Furthermore, we show that such an immunological mechanism is compromised in patients with SLE. Establishing mice with either conditional knockout (cKO) or knockin (cKI) of the E4bp4 gene in T cells reveals that E4BP4 strongly inhibits Tfh cell differentiation. Mechanistically, E4BP4 regulates Bcl6 transcription by recruiting the repressive epigenetic modifiers HDAC1 and EZH2. E4BP4 phosphorylation site mutants have limited capability with regard to inhibiting Tfh cell differentiation. In SLE, we detected impaired phosphorylation of E4BP4, finding that this compromised transcription factor is positively correlated with disease activity. These findings unveiled molecular mechanisms by which E4BP4 restrains Tfh cell differentiation, whose compromised function is associated with uncontrolled autoimmune reactions in SLE.