Oxygen Plasma-Assisted Defect Engineering of Graphene Nanocomposites with Ultrasmall Co3O4 Nanocrystals for Monitoring Toxic Nitrogen Dioxide at Room Temperature.

Functional adjustment of graphene with metal oxide can in fact progress the affectability of graphene-based gas sensors. However, it could be a huge challenge to upgrade the detecting execution of nitrogen dioxide (NO2) sensors at room temperature. The ultrasmall size of nanocrystals (NCs) and copious defects are two key variables for moving forward gas detecting execution. Herein, we provide an effective strategy that the hydrothermal reaction is combined with room-temperature oxygen plasma treatment to prepare Co3O4 NCs and reduced graphene oxide (RGO) nanohybrids (Co3O4-RGO). Among all of Co3O4-RGO nanohybrids, Co3O4-RGO-60 W exhibits the most superior NO2 sensing properties and achieves the low-concentration detection of NO2. The sensitivity of Co3O4-RGO-60 W to 20 ppm NO2 at room temperature is the highest (72.36%). The excellent sensing properties can mainly depend on the change in the microstructure of Co3O4-RGO. Compared with Co3O4-RGO, Co3O4-RGO-60 W with oxygen plasma treatment shows more favorable properties for NO2 adsorption, including the smaller size of Co3O4 NCs, larger specific surface area, pore size, and more oxygen vacancies (OVs). Especially, OVs make the surface of NCs have a unique chemical state, which can increase active sites and improve the adsorption property of NO2. Besides, the agreeable impact of the p-p heterojunction (Co3O4 and RGO) and the doping of N molecule contribute to the improved NO2 detecting properties. It is demonstrated that the Co3O4-RGO-60 W sensor is expected to monitor NO2 at room temperature sensitively.

[Chemical constituents from fruits of Aristolochia mollissima and their nematicidal activity against root-knot nematode].

In the present study, in vitro nematicidal activity of chemical compositions from the methanol extract of Aristolochia mollissima fruits against the second stage juvenile (J2) of Meloidogyne javanica have been investigated. By using silica gel column chromatography, Sephadex LH-20 gel column chromatography methods, fourteen compounds were isolated from methanol extract of A. mollissima fruits. On the basis of spectral data, their structures were identified as aristolochic acid I (1), aristololactam I (2), aristololactam W (3), manshurolide (4), aristolactone (5), saropeptate (6), 2-(1-oxononadecyl)aminobenzoic acid (7), ß-sitosterol (8), sitostanetriol (9), daucosterol (10), formosolic acid (11), 5-ethyl-8,8-dimethyl nonanal (12), tetracosanoic acid,2,3-dihydroxypropyl ester (13) and tetracosanoic acid (14), respectively. It is the first time that compounds 2-4, 6-7, 9-14 are separated from A. mollissima. Furthermore, nematicidal activity of fourteen monomer compounds against J2 Meloidogyne javanica in vitro were analyzed. The compounds 1-3, 6-7 exhibited different degrees toxic effects on J2 M. javanica in vitro, especially for aristolochic acid I (1), aristololactam I (2), aristololactam W (3) with the LC50 values of 45.25, 36.56, 119.46 mg·L⁻¹ after 96 h. So, A. mollissima have the potential value of developing new plant source to control root nematodes.

Flexible, non-contact and multifunctional humidity sensors based on two-dimensional phytic acid doped co-metal organic frameworks nanosheets.

The development of high-performance humidity sensors is of great significance to explore their practical applications in the fields of environment, energy saving and safety monitoring. Herein, a flexible, non-contact and multifunctional humidity sensor based on two-dimensional Co-metal organic frameworks (Co-MOF) nanosheets is proposed, which is fabricated by simple bottom-up synthesis method. Furthermore, environmentally friendly, renewable and abundant biomass phytic acid (PA) is modified on the surface of Co-MOF nanosheets, which releases free protons being capable of etching the framework of MOF to improve the hydrophilicity and conductivity of MOF. Compared with Co-MOF-based sensor, the Co-MOF@PA-based sensor exhibits significantly enhanced sensitivity and broadened response range within 23-95% relative humidity (RH). The humidity sensor has an excellent humidity sensing response over 2 × 103. The Co-MOF@PA-based sensor shows good flexibility and humidity sensing properties, endowing it with multifunctional applications in real-time facial respiration monitoring, skin humidity perception, cosmetic moisturizing evaluation and fruit freshness testing. Four respiration patterns, including slow breath, deep breath, normal breath and fast breath are wirelessly monitored in real time by Co-MOF@PA-based sensor and recorded by mobile phone software. The research work presents potential applications in human-machine interactions (HMI) devices in future.

Recent Advances in Natural Functional Biopolymers and Their Applications of Electronic Skins and Flexible Strain Sensors.

In order to replace nonrenewable resources and decrease electronic waste disposal, there is a rapidly rising demand for the utilization of reproducible and degradable biopolymers in flexible electronics. Natural biopolymers have many remarkable characteristics, including light weight, excellent mechanical properties, biocompatibility, non-toxicity, low cost, etc. Thanks to these superior merits, natural functional biopolymers can be designed and optimized for the development of high-performance flexible electronic devices. Herein, we provide an insightful overview of the unique structures, properties and applications of biopolymers for electronic skins (e-skins) and flexible strain sensors. The relationships between properties and sensing performances of biopolymers-based sensors are also investigated. The functional design strategies and fabrication technologies for biopolymers-based flexible sensors are proposed. Furthermore, the research progresses of biopolymers-based sensors with various functions are described in detail. Finally, we provide some useful viewpoints and future prospects of developing biopolymers-based flexible sensors.

Aristololactam derivatives from the fruits of Aristolochia contorta Bunge.

Three new aristololactam derivatives, aristololactam W-Y (1-3), and three known compounds (4-6) were isolated from the fruits of Aristolochia contorta Bunge. Compounds 1 and 2 represent the first example of an N-CH2OCH3 aristololactam derivative from natural products. Their structures were elucidated by 1D/2D NMR and HRESIMS spectra. All of the isolated compounds were evaluated for their insecticidal activity against 4th instar larvae of Aedes aegypti. Compound 4 displayed insecticidal activity with LC50 value of 3.54 µg/mL.