Kirkendall effect induced ultrafine VOOH nanoparticles and their transformation into VO2(M) for energy-efficient smart windows.

Vanadium dioxide (VO2) has received widespread attention for application in energy-efficient smart windows because of its distinct thermochromic property in the near-infrared region during the reversible metal-insulator phase transition. In this study, lepidocrocite VOOH ultrafine nanoparticles (NPs) with a diameter less than 30 nm were prepared by a mild and efficient hydrothermal method, and the Kirkendall effect played a vital role in the growth of the VOOH NPs. It was found that VOOH could be transformed into VO2via a subsequent annealing treatment during which the size and morphology of VOOH are well preserved even though the annealing temperature is up to 500 °C. The ultrafine VO2 NPs are crucial for achieving excellent nanothermochromic performance with a luminous transmittance (Tlum) up to 56.45% and solar modulation ability (ΔTsol) up to 14.95%. The environmental durability is well improved by coating VO2 NPs with an SiO2 shell as confirmed via progressive oxidation and acid corrosion experiments. Meanwhile, the Tlum of the VO2@SiO2 film is further increased from 56.45% to 62.29% while the ΔTsol remained unchanged. This integrated thermochromic performance presents great potential for the development of VO2-based smart windows.

Facile Synthesis of Two Dimensional (2D) V2O5 Nanosheets Film towards Photodetectors.

Most of the studies focused on V2O5 have been devoted to obtaining specific morphology and microstructure for its intended applications. Two dimensional (2D) V2O5 has the most valuable structure because of its unique planar configuration that can offer more active sites. In this study, a bottom-up and low-cost method that is hydrothermal combined with spin-coating and subsequent annealing was developed to prepare 2D V2O5 nanosheets film on quartz substrate. First, VOOH nanosheets were prepared by the hydrothermal method using V2O5 powders and EG as raw materials. Further, V2O5 nanosheets with an average lateral size over 500 nm and thickness less than 10 nm can be prepared from the parent VOOH nanosheets by annealing at 350 °C for 15 min in air. The prepared V2O5 nanosheets film was assembled of multiple nanosheets. The structural, morphological, microstructural and optical properties of the films were respective investigated by XRD, SEM, TEM and UV-Vis. The photodetector based on V2O5 nanosheets film shows good photoresponse with a response time of 2.4 s and a recovery time of 4.7 s.

A Thermal-Switchable Metamaterial Absorber Based on the Phase-Change Material of Vanadium Dioxide.

This article presents a thermal-switchable metamaterial absorber (TSMA) based on the phase-change material of vanadium dioxide (VO2). VO2 thin film was deposited on sapphire substrate by magnetron sputtering followed by vacuum annealing treatment. Then, the prepared VO2 film was sliced into tiny chips for thermal-switchable elements. The surface structure of TSMA was realized by loading four VO2 chips into a square metallic loop. The absorption frequency of TSMA was located at 7.3 GHz at room temperature and switched to 6.8 GHz when the temperature was heated above the critical phase transition temperature of VO2. A VO2-based TSMA prototype was fabricated and measured to verify this design. The design is expected to be used in metasurface antennas, sensors, detectors, etc.

A Submicrosecond-Response Ultraviolet-Visible-Near-Infrared Broadband Photodetector Based on 2D Tellurosilicate InSiTe3.

2D material (2DM) based photodetectors with broadband photoresponse are of great value for a vast number of applications such as multiwavelength photodetection, imaging, and night vision. However, compared with traditional photodetectors based on bulk material, the relatively slow speed performance of 2DM based photodetectors hinders their practical applications. Herein, a submicrosecond-response photodetector based on ternary telluride InSiTe3 with trigonal symmetry and layered structure was demonstrated in this study. The InSiTe3 based photodetectors exhibit an ultrafast photoresponse (545-576 ns) and broadband detection capabilities from the ultraviolet (UV) to the near-infrared (NIR) optical communication region (365-1310 nm). Besides, the photodetector presents an outstanding reversible and stable photoresponse in which the response performance remains consistent within 200 000 cycles of switch operation. These significant findings suggest that InSiTe3 can be a promising candidate for constructing fast response broadband 2DM based optoelectronic devices.

Pd-Catalyzed ß-C-H Arylation of Aldehydes and Ketones Based on a Transient Directing Group.

The direct Pd-catalyzed ß-C-H arylation of aldehydes and ketones was developed by using 2-amino-N,N'-diisopropylsuccinamide as a novel transient directing group (TDG). The TDG showed good versatility in functionalizing unactivated ß-C-H bonds of aldehydes and ketones. It was effective not only for aliphatic aldehydes and ketones but also for aromatic aldehydes and ketones. Besides, it was applicable to o-methylbenzaldehydes.

Palladium-Catalyzed ß-C-H Arylation of Aliphatic Aldehydes and Ketones Using Amino Amide as a Transient Directing Group.

This paper describes a new amino-amide-based transient directing group (TDG). The TDG can exhibit better performance in the Pd-catalyzed arylation of aliphatic aldehydes and ketones. This reaction showed good substrate compatibility and regioselectivity. The results indicated that 3-amino- N-isopropylpropionamide was more beneficial to the ß-arylation of aliphatic aldehydes than other TDGs under relatively mild conditions.

[Preparation of sustained release microspheres containing oxymatrine and their release characteristics in vitro].

OBJECTIVE: To prepare poly(lactide-co-glycolide) (PLGA) microspheres containing Oxymatrine (OMT-PLGA-MS) and study their release characteristics in vitro. METHODS: OMT-PLGA-MS was prepared with PLGA as carriers using double emulsion solvent evaporation method (W/O/W). The preparation technology of microspheres was optimized by orthogonal design, and the microspheres were characterized in terms of morphology, the rate of drug loading, encapsulation efficiency, and in vitro drug release. RESULTS: The formed microspheres were spherical with smooth surfaces and the average size was (98.3 +/- 3.4) microm. The encapsulation efficiency and rate of drug loading were (70.14 +/- 3.47)% and (21.59 +/- 1.07)%, respectively. In vitro release study revealed that 84.63% of OMT was released from OMT-PLGA-MS in 240 hours, and the Higuchi model fitted OMT release pattern best. CONCLUSION: OMT-PLGA-MS is prepared successfully and shows good sustained release characteristics.