Glass-like thermal conductivity and phonon transport mechanism in disordered crystals.

Solid materials with ultra-low thermal conductivity (κ) are of great interest in thermoelectrics for energy conversion or as thermal barrier coatings for thermal insulation. Many low-κ materials exhibit unique properties, such as weak or even insignificant dependence on temperature (T) for κ, i.e., an anomalous glass-like behavior. However, a comprehensive theoretical model elucidating the microscopic phonon mechanism responsible for the glass-like κ-T relationship is still absent. Herein, we take rare-earth tantalates (RE3TaO7) as examples to reexamine phonon thermal transport in defective crystals. By combining experimental studies and atomistic simulations up to 1800 K, we revealed that diffusion-like phonons related to inhomogeneous interatomic bonding contribute more than 70% to the total κ, overturning the conventional understanding that low-frequency phonons dominate heat transport. Furthermore, due to the bridging effects of interatomic bonding, the κ of high-entropy tantalates is not necessarily lower than that of medium-entropy materials, suggesting that attempts to reduce κ through high-entropy engineering are limited, at least in defective fluorite tantalates. The new physical mechanism of multimodal phonon thermal transport in defective structures demonstrated in this work provides a reference for the analysis of phonon transport and offers a new strategy to develop and design low-κ materials by regulating the inhomogeneity of interatomic bonding.

Lymphocyte Membrane- and 12p1-Dual-Functionalized Nanoparticles for Free HIV-1 Trapping and Precise siRNA Delivery into HIV-1-Infected Cells.

Despite the success of small interfering RNA (siRNA) in clinical settings and its potential value in human immunodeficiency virus (HIV) therapy, the rapid clearance and absence of precise delivery to target cells still hinder the therapeutic effect of siRNA. Herein, a new system, which can escape immune recognition, has HIV-1 neutralizing capacity, and the ability to deliver siRNA specifically into HIV-1-infected cells, is constructed by functionalizing siRNA delivery lipid nanoparticles with the lymphocyte membrane and 12p1. The constructed system is shown to escape uptake by the mononuclear phagocyte system. The constructed system exhibits strong binding ability with gp120, thus displaying distinguished neutralizing breadth and potency. The constructed system neutralizes all tested HIV-1 pseudotyped viruses with a geometric mean 80% inhibitory concentration (IC80) of 29.75 µg mL-1 and inhibits X4-tropic HIV-1 with an IC80 of 64.20 µg mL-1 , and R5-tropic HIV-1 with an IC80 of 16.39 µg mL-1 . The new system also specifically delivers siRNA into the cytoplasm of HIV-1-infected cells and exhibits evident gene silencing of tat and rev. Therefore, this new system can neutralize HIV-1 and deliver siRNA selectively into HIV-1-infected cells and may be a promising therapeutic candidate for the precise therapy of HIV.

Advances in Cellulose-Based Hydrogels for Biomedical Engineering: A Review Summary.

In recent years, hydrogel-based research in biomedical engineering has attracted more attention. Cellulose-based hydrogels have become a research hotspot in the field of functional materials because of their outstanding characteristics such as excellent flexibility, stimulus-response, biocompatibility, and degradability. In addition, cellulose-based hydrogel materials exhibit excellent mechanical properties and designable functions through different preparation methods and structure designs, demonstrating huge development potential. In this review, we have systematically summarized sources and types of cellulose and the formation mechanism of the hydrogel. We have reviewed and discussed the recent progress in the development of cellulose-based hydrogels and introduced their applications such as ionic conduction, thermal insulation, and drug delivery. Also, we analyzed and highlighted the trends and opportunities for the further development of cellulose-based hydrogels as emerging materials in the future.

An intrinsic room-temperature half-metallic ferromagnet in a metal-free PN2 monolayer.

In spintronics, the embodiment of abundance availability, long spin relaxation time, complete spin-polarization and high Curie temperature (TC) in intrinsic metal-free half-metallic ferromagnets (MFHMFs) are highly desirable and challenging. In this work, employing density functional theory, we first propose a dynamically, thermally, and mechanically stable two-dimensional (2D) intrinsic MFHMF, i.e. a MoS2-like PN2 monolayer, which possesses not only completely spin-polarized half-metallicity, but also an above-room-temperature TC (385 K). The half-metallic gap is calculated to be 1.70 eV, which can effectively prevent the spin-flip transition caused by thermal agitation. The mechanism of magnetism in the PN2 monolayer is mainly derived from the p electron direct exchange interaction that separates from usual d-state magnetic materials. Moreover, the robustness of the ferromagnetism and half-metallicity is observed against an external strain and carrier (electron or hole) doping. Surprisingly, electron doping can effectively increase the Curie temperature of the PN2 monolayer. The proposed research work provides an insight that PN2 can be a promising candidate for realistic room-temperature metal-free spintronic applications.