Due to the advantages of good scalability, flexibility, low cost, ease of processing, 3D-stacking capability, and large capacity for data storage, polymer-based resistive memories have been a promising alternative or supplementary devices to conventional inorganic semiconductor-based memory technology, and attracted significant scientific interest as a new and promising research field. In this review, we first introduced the general characteristics of the device structures and fabrication, memory effects, switching mechanisms, and effects of electrodes on memory properties associated with polymer-based resistive memory devices. Subsequently, the research progress concerning the use of single polymers or polymer composites as active materials for resistive memory devices has been summarized and discussed. In particular, we consider a rational approach to their design and discuss how to realize the excellent memory devices and understand the memory mechanisms. Finally, the current challenges and several possible future research directions in this field have also been discussed.
The worldwide incidence of bone disorders and conditions has been increasing. Bone is a nanomaterials composed of organic (mainly collagen) and inorganic (mainly nano-hydroxyapatite) components, with a hierarchical structure ranging from nanoscale to macroscale. In consideration of the serious limitation in traditional therapies, nanomaterials provide some new strategy in bone regeneration. Nanostructured scaffolds provide a closer structural support approximation to native bone architecture for the cells and regulate cell proliferation, differentiation, and migration, which results in the formation of functional tissues. In this article, we focused on reviewing the classification and design of nanostructured materials and nanocarrier materials for bone regeneration, their cell interaction properties, and their application in bone tissue engineering and regeneration. Furthermore, some new challenges about the future research on the application of nanomaterials for bone regeneration are described in the conclusion and perspectives part.
SARS‐CoV‐2, a novel emerging coronavirus, has caused severe disease (COVID‐19), and rapidly spread worldwide since the beginning of 2020. SARS‐CoV‐2 mainly spreads by coughing, sneezing, droplet inhalation, and contact. SARS‐CoV‐2 has been detected in saliva samples, making saliva a potential transmission route for COVID‐19. The participants in dental practice confront a particular risk of SARS‐CoV‐2 infection due to close contact with the patients and potential exposure to saliva‐contaminated droplets and aerosols generated during dental procedures. In addition, saliva‐contaminated surfaces could lead to potential cross‐infection. Hence, the control of saliva‐related transmission in the dental clinic is critical, particularly in the epidemic period of COVID‐19. Based on our experience of the COVID‐19 epidemic, some protective measures that can help reduce the risk of saliva‐related transmission are suggested, in order to avoid the potential spread of SARS‐CoV‐2 among patients, visitors, and dental practitioners.
Subunit vaccines generally proceed through a 4-step in vivo cascade—the DUMP cascade—to generate potent cell-mediated immune responses: (1) drainage to lymph nodes; (2) uptake by dendritic cells (DCs); (3) maturation of DCs; and (4) Presentation of peptide-MHC I complexes to CD8+ T cells. How the physical properties of vaccine carriers such as mesoporous silica nanoparticles (MSNs) influence this cascade is unclear. We fabricated 80-nm MSNs with different pore sizes (7.8 nm, 10.3 nm, and 12.9 nm) and loaded them with ovalbumin antigen. Results demonstrated these MSNs with different pore sizes were equally effective in the first three steps of the DUMP cascade, but those with larger pores showed higher cross-presentation efficiency (step 4). Consistently, large-pore MSNs loaded with B16F10 tumor antigens yielded the strongest antitumor effects. These results demonstrate the promise of our lymph node-targeting large-pore MSNs as vaccine-delivery vehicles for immune activation and cancer vaccination.
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