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Atherosclerotic plaque formation is largely attributed to the impaired efferocytosis, which is known to be associated with the pathologic upregulation of cluster of differentiation 47 (CD47), a key antiphagocytic molecule. By gene expression omnibus (GEO) datasets analysis, we identified that four miRNAs are aberrantly downregulated in atherosclerosis, coronary artery disease, and obesity. Of them, hsa‐miR‐299‐3p (miR‐299‐3p) was predicted to target the 3′UTR of human CD47 mRNA by bioinformatics analysis. Further, we demonstrated that miR‐299‐3p negatively regulates CD47 expression by binding to the target sequence "CCCACAU" in the 3′UTR of CD47 mRNA through luciferase reporter assay and site‐directed mutagenesis. Additionally, we found that miR‐299‐3p was downregulated by ~32% in foam cells in response to oxidized low‐density lipoprotein (ox‐LDL) stimulation, thus upregulating CD47 and contributing to the impaired efferocytosis. Whereas, restoration of miR‐299‐3p reversed the ox‐LDL‐induced upregulation of CD47, thereby facilitating efferocytosis. In high‐fat diet (HFD) fed ApoE−/− mice, we discovered that miR‐299‐3p was downregulated thus leading to upregulation of CD47 in abdominal aorta. Conversely, miR‐299‐3p restoration potently suppressed HFD‐induced upregulation of CD47 and promoted phagocytosis of foam cells by macrophages in atherosclerotic plaques, thereby reducing necrotic core, increasing plaque stability, and mitigating atherosclerosis. Conclusively, we identify miR‐299‐3p as a negative regulator of CD47, and reveal a molecular mechanism whereby the ox‐LDL‐induced downregulation of miR‐299‐3p leads to the upregulation of CD47 in foam cells thus contributing to the impaired efferocytosis in atherosclerosis, and propose miR‐299‐3p can potentially serve as an inhibitor of CD47 to promote efferocytosis and ameliorate atherosclerosis. [ABSTRACT FROM AUTHOR]

SiBCN ceramics have a wide range of applications in the field of high temperature electromagnetic wave (EMW) absorption owing to their excellent EMW attenuation and oxidation resistance. However, excessive SiC and insufficient Si3N4 in the SiBCN ceramics deteriorate the impedance matching characteristics, and weaken the absorption ability for EMW. In this paper, the amount of SiC and Si3N4 is balanced by a competitive reaction strategy, in which HfZr atoms are introduced to modulate the dielectric phases in the SiBCN ceramics. The formation of a HfZrCN compound produces a cage-like structure around Si3N4, inhibiting the reaction of Si3N4 with carbon to form SiC. The appropriate amounts of SiC and Si3N4, and the abundant interfaces and defects jointly enhance the EMW absorption capability by simultaneously improving the impedance matching and attenuation capability. Thus, an effective absorption band of 4.96 GHz (11.20–16.16 GHz) is reached with a thickness of 1.7 mm for the HfZr-SiBCN ceramics. This work provides a new strategy for simultaneously improving the impedance matching and EMW attenuation capability of polymer-derived ceramics by introducing difficult-to-migrate atoms to regulate the content of the dielectric phase. [ABSTRACT FROM AUTHOR]

So far, developed microwave absorbers exhibit significant changes in absorption with temperature, which hinder their operation within a wide temperature range. In this paper, a microwave absorber based on SiBCN ceramics was prepared. Due to the excellent high‐temperature stability of SiBCN ceramics, its permittivity changes less with temperature, avoiding the issue of performance deterioration or even failure that traditional refractory absorbers face at high temperatures. The experiment proves the absorption bandwidth for –15 dB of the SiBCN metamaterials absorber (SMA) is 12 GHz at 800°C, with a maximum absorptivity of 99.99%. According to the computed data, the resonance loss contributes 81.9 to 94.5% of the microwave absorption of SMA. This work demonstrates significant potential for applications in radar stealth under harsh conditions. [ABSTRACT FROM AUTHOR]

Although human pluripotent stem cell (PSC)‐derived brain organoids have enabled researchers to gain insight into human brain development and disease, these organoids contain solely ectodermal cells and are not vascularized as occurs during brain development. Here it is created less complex and more homogenous large neural constructs starting from PSC‐derived neuroprogenitor cells (NPC), by fusing small NPC spheroids into so‐called concentroids. Such concentroids consisted of a pro‐angiogenic core, containing neuronal and outer radial glia cells, surrounded by an astroglia‐dense outer layer. Incorporating PSC‐derived endothelial cells (EC) around and/or in the concentroids promoted vascularization, accompanied by differential outgrowth and differentiation of neuronal and astroglia cells, as well as the development of ectodermal‐derived pericyte‐like mural cells co‐localizing with EC networks. Single nucleus transcriptomic analysis revealed an enhanced neural cell subtype maturation and diversity in EC‐containing concentroids, which better resemble the fetal human brain compared to classical organoids or NPC‐only concentroids. This PSC‐derived "vascularized" concentroid brain model will facilitate the study of neurovascular/blood‐brain barrier development, neural cell migration, and the development of effective in vitro vascularization strategies of brain mimics. [ABSTRACT FROM AUTHOR]