Due to their low operating voltage, high on/off ratio, and tunable band gap, Cs2AgBiBr6–xClx halide double perovskites (DPs) are being considered as promising materials for lead-free resistive switching (RS) memory devices. However, while the performance of conventional halide DP-based RS memory devices can be significantly improved by changing composition of halide materials, the mechanisms behind materials composition and its effects on performance are often insufficiently understood. This study reports on the effects of halide composition in DP-based RS memory devices. The Cs2AgBiBr4Cl2 device demonstrates enhanced properties, with an endurance of 6500 cycles at room temperature and a retention of 10000 s at 100 °C. The thermal ion activation energy and time-of-flight secondary-ion-mass spectrometry revealed that the halide DP-based RS memory devices operate via an electrochemical metallization mechanism due to the migration of Cu ions. Additionally, studies on cohesive energies through first-principles simulations and thermal stability via thermogravimetric analysis demonstrate that the improved stability of halide DPs effectively increases the formation voltage by retarding Cu ion migration, thereby leading to enhanced endurance and retention properties. This report proposes a relationship between the change in halide composition and endurance and retention properties of lead-free DP-based RS memory devices.
Dendritic cell (DC)-based cancer immunotherapies have been studied extensively. In cancer immunotherapy, the initial key step is the delivery of tumor-specific antigens, leading to the maturation and activation of DCs. To promote effective antigen delivery, liposome-based delivery systems for tumor-specific antigens have been investigated, and although promising, a triggered release of the antigen from the liposome is required to attain an optimum immune response. In this study, we developed CO2-bubble-generating thermosensitive liposomes (BG-TSLs) that encapsulate whole tumor cell lysates (TCLs). The release of the lysate from BG-TSLs can be triggered using near-infrared (NIR) irradiation. We also developed BG-TSLs able to encapsulate doxorubicin (DOX) for combination therapy. The DOX-BG-TSLs and TCL-BG-TSLs have a mean particle size of 114.17 ± 8.28 nm and 123.8 ± 10.2 nm and a surface charge of -22.56 ± 1.3 mV and -28.9 ± 0.8 mV, respectively. CO2 bubble generation within TCL-BG-TSLs and DOX-BG-TSLs by NIR irradiation led to the burst release of TCL or DOX. TCL release from TCL-BG-TSLs promoted dendritic cell maturation and activation, leading to the emergence of antigen-specific cytotoxic CD8+ T cells. The combination of TCL-BG-TSLs with DOX-BG-TSLs showed a significantly greater antitumor efficacy in B16F10 tumor-bearing mice compared to that seen in the control mice (P < 0.001). Taken together, our liposomal delivery system, combined with NIR irradiation, could enhance the therapeutic efficacy of cancer immunotherapies.
Bioinspired yarn/fiber structured hydro-actuators have recently attracted significant attention. However, most water-driven mechanical actuators are unsatisfactory because of the slow recovery process and low full-time power density. A rapidly recoverable high-power hydro-actuator is reported by designing biomimetic carbon nanotube (CNT) yarns. The hydrophilic CNT (HCNT) coiled yarn was prepared by storing pre-twist into CNT sheets and subsequent electrochemical oxidation (ECO) treatment. The resulting yarn demonstrated structural stability even when one end was cut off without the possible loss of pre-stored twists. The HCNT coiled yarn actuators provided maximal contractile work of 863 J/kg at 11.8 MPa stress when driven by water. Moreover, the recovery time of electrically heated yarns at a direct current voltage of 5 V was 95% shorter than that of neat yarns without electric heating. Finally, the electrothermally recoverable hydro-actuators showed a high actuation frequency (0.17 Hz) and full-time power density (143.8 W/kg).
Photoelectrochemical (PEC) water splitting with metal oxides photoelectrodes is a promising renewable technology because of their good performance for light harvesting and stability as well as good properties such as naturally earth-abundant, harmless and economical. BiVO4 has been regarded as a major metal oxide material in the PEC photoanode due to the suitable band gap for efficient light absorption and advantage of solar-to-hydrogen conversion efficiency. However, the PEC performance of this single absorber material is limited due to its charge recombination in bulk, interface and surface derived by poor carrier diffusion property, electrical conductivity and water oxidation kinetics. Until now, many attempts of junction of two materials such as BiVO 4 /WO 3 , BiVO 4 /ZnO or BiVO 4 /Bi 2 WO 6 to form a type-II heterojunction has been introduced to be a feasible mean to improve the charge separation and transport efficiencies. In this study, we have modified the BiVO 4 single absorber with Zn and Mo doping and introduced the type-II homojunction BiVO 4 photoanode for efficient PEC water splitting via a facile solution method. Interestingly, the Zn and Mo doping treatment let BiVO 4 thin-film change the Fermi level and form the staggered band alignment. It is helpful to enhance the charge separation in bulk and charge transfer in surface of BiVO 4 due to the interference of surface trapping of photogenerated charge carriers with type-II homojunction followed by the enhancement of PEC water splitting performances.
Electrically tunable focusing microlens arrays based on polarization independent optical phase of nano liquid crystal droplets dispersed in polymer matrix are demonstrated. Such an optical medium is optically isotropic which is so-called an optically isotropic liquid crystals (OILC). We not only discuss the optical theory of OILC, but also demonstrate polarization independent optical phase modulation based on the OILC. The experimental results and analytical discussion show that the optical phase of OILC microlens arrays results from mainly orientational birefringence which is much larger than the electric-field-induced birefringence (or Kerr effect). The response time of OILC microlens arrays is fast~5.3ms and the tunable focal length ranges from 3.4 mm to 3.8 mm. The potential applications are light field imaging systems, 3D integrating imaging systems and devices for augment reality.
The structures of 19 single crystals of ZIF-8 that were subjected to different thermal treatments have been determined. Crystal 1 was as-synthesized from an in situ synthetic batch. Crystals 2–12 were thermally treated at various temperatures under dynamic vacuum for 48 h. A dehydrated ZIF-8 was rehydrated by flowing distilled water at 293 K for 1 h (crystal 13). Crystals 14–19 were thermally treated at 798 K under dynamic vacuum for 1, 2, 3, 4, 5, and 6 h, respectively. Their crystal structures were completely determined by single-crystal synchrotron X-ray diffraction techniques in the cubic space group I4̅3m at 100(1) K. In the structures of crystals 1 and 2, about 20 and 0.8 water molecules per unit cell occupied two crystallographic sites at O1 (opposite 4-ring) and O2 (center of 6-ring plane). Unlike the crystals 1 and 2, a trace amount of water molecules found only one crystallographic site at O2 in the structures of crystals 3–10. The crystals 11, 12, and 14 were completely dehydrated. In the structure of crystal 13, about 33 water molecules were readsorbed not only at O1 and O2 sites but also at the new site O3. In the structures of crystals 15–19, partial demethylation of 2-methylimidazolate ligands in ZIF-8 occurred, and the remaining methyl group of 2-methylimidazolate ligands were found with the occupancies of 22.4(3), 21.8(3), 20.7(5), 20.6(4), and 16.6(13), respectively.
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