Visible Light-Catalyzed Reactions of Polysulfide (DBSPS) with Aryldiazonium

A visible light-catalyzed radical coupling reaction of polysulfide reagents with aryldiazonium was developed, which gave thiosulfonates under mild conditions. In this reaction, the thiosulfonates were isolated in good yields with a broad tolerance to functional groups. And the synthesis of diaryl monosulfides were achieved through a step-by-step reaction of two molecular aryldiazonium with DBSPS, where the sulfur source was provided by DBSPS. It was worth noting that the reaction of this monosulfides could also be achieved by a one pot two-step process. The described polysulfide reagents were able to produce three new radicals: sulfonyl radicals, sulfur-sulfonyl radicals and sulfur-sulfur-sulfonyl radicals.

Uracil Induced Simultaneously Strengthening Grain Boundaries and Interfaces Enables High-Performance Perovskite Solar Cells with Superior Operational Stability

The operational stability is a huge obstacle to further commercialization of perovskite solar cells. To address this critical issue, in this work, uracil is introduced as a "binder" into the perovskite film to simultaneously improve the power conversion efficiency (PCE) and operational stability. Uracil can efficiently passivate defects and strengthen grain boundaries to enhance the stability of perovskite films. Moreover, the uracil also strengthens the interface between the perovskite and the Tin oxide (SnO2 ) electron transport layer to increase the binding force. The uracil-modified devices deliver a champion PCE of 24.23% (certificated 23.19%) with negligible hysteresis at active area of 0.0625 cm2 . In particular, the optimal device exhibits over 90% of its initial PCE after tracking for ≈6000 h at its maximum power point under continuous light, indicating its superior operational stability. Moreover, the devices also show great reproducibility in both PCE and operational stability.

Synthesis of Azoxy Compounds: from Copper Compounds to Mesoporous Silica-Encaged Ultrasmall Copper Catalysts

Azoxy compounds have aroused extensive attention due to their unique biological activities, but the chemical synthesis of these compounds often suffers from limitations due to their requirement for stoichiometric oxidants, high costs, and restricted substrate range. Herein, a series of azoxy compounds were constructed via facile coupling reactions by using cost-effective N-methoxyformamide and nitroso compounds over Cu-based catalysts, affording high product yields with excellent tolerance of functional groups. Significantly, the mesoporous silica nanosphere-encapsulated ultrasmall Cu (Cu@MSN) catalyst was developed via a one-pot synthetic method and first used for the synthesis of azoxy compounds. As compared with copper salt catalysts, the Cu@MSN catalyst exhibited remarkably enhanced catalytic activity and superior recycling stability. Such a Cu@MSN catalyst overcame the inherent drawbacks of low activity, fast deactivation, and difficult recycling of traditional metal salt catalysts in organic reactions. This work provides a green and efficient method for the construction of azoxy compounds and also creates new prospects for the application of nanoporous materials confined metal catalysts in organic synthesis.

A novel Bacillus sp. with antagonistic activity against a plant pathogen, Fusarium graminearum, and its potential antagonistic mechanism

Fusarium head blight (FHB) is a wheat disease caused by the plant pathogen Fusarium graminearum, which leads to crop yield losses and agricultural economic losses, as well as poses a threat to the environment and human health. Effective biocontrol of F. graminearum is urgent. An antagonistic strain HZ-5 with 59.2% antagonistic activity against F. graminearum in vitro had been isolated from sea mud of Haizhou Bay using a dual-culture assay, which was highly homologous with Bacillus halosaccharovorans according to the 16S rRNA sequence. The antagonistic activity of HZ-5 had been further studied. HZ-5 had a broad range of antagonistic activity against another six plant pathogenic fungi and was effective in controlling FHB of wheat in pot experiment. The substances with antagonistic activity were temperature insensitive, and had been purified by HPLC (High Performance Liquid Chromatography) to prove to be secreted lipopeptides. The antagonistic substances induced the biosynthesis of chitin and glycerol, while ergosterol , cholesterol, and phosphatidylcholine reduced their inhibitory effects on F. graminearum. These data would be helpful to provide a better biocontrol strain against FHB, and to provide important basis to elucidate the antagonistic mechanism of biocontrol.

A Direct-Writing Approach for Fabrication of CNT/Paper-Based Piezoresistive Pressure Sensors for Airflow Sensing

Airflow sensor is a crucial component for monitoring environmental airflow conditions in many engineering fields, especially in the field of aerospace engineering. However, conventional airflow sensors have been suffering from issues such as complexity and bulk in structures, high cost in fabrication and maintenance, and low stability and durability. In this work, we developed a facile direct-writing method for fabricating a low-cost piezoresistive element aiming at high-performance airflow sensing, in which a commercial pen was utilized to drop solutions of single-walled carbon nanotubes onto tissue paper to form a piezoresistive sensing element. The encapsulated piezoresistive element was tested for electromechanical properties under two loading modes: one loading mode is the so-called pressure mode in which the piezoresistive element is pressed by a normal pressure, and another mode is the so-called bending mode in which the piezoresistive element is bended as a cantilever beam. Unlike many other developed airflow sensors among which the sensing elements are normally employed as cantilever beams for facing winds, we designed a fin structure to be incorporated with the piezoresistive element for airflow sensing; the main function of the fin is to face winds instead of the piezoresistive element, and subsequently transfer and enlarge the airflow pressure to the piezoresistive element for the normal pressure loading mode. With this design, the piezoresistive element can also be protected by avoiding experiencing large strains and direct contact with external airflows so that the stability and durability of the sensor can be maintained. Moreover, we experimentally found that the performance parameters of the airflow sensor could be effectively tuned by varying the size of the fin structure. When the fin sizes of the airflow sensors were 20 mm, 30 mm, and 40 mm, the detection limits and sensitivities of the fabricated airflow sensors were measured as 8.2 m/s, 6.2 m/s, 3.2 m/s, 0.0121 (m/s)-2, 0.01657 (m/s)-2, and 0.02264 (m/s)-2, respectively. Therefore, the design of the fin structure could pave an easy way for adjusting the sensor performance without changing the sensor itself toward different application scenarios.