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Vegetable growth requires a relatively stable environment for the root zone. If the temperature in root zone environment is optimal, the aeroponic cultivation will be energy-efficient, and the aeroponic vegetables will grow well at high, normal, or low temperature. By computational fluid dynamics (CFD), this paper numerically simulates the root zone temperature of lettuce in the aeroponic cultivation box, after the box was sprayed with nutrient solutions of different temperatures. Then, the root zone environments of aeroponic lettuce were monitored through experiments at three different temperatures: high temperature, normal temperature, and low temperature. Through comparison, it was learned that the error between the simulated and measured values at each point was smaller than 1.35℃; the maximum error at a single point was within 7.4%; overall, the mean relative error was merely 5.8%. The results prove that the proposed CFD simulation model is reasonable and effective. Our research provides a theoretical reference for optimizing the root zone temperature, regulating the spray of nutrient solutions at different temperatures, and building an energy-efficient efficient aeroponic cultivation system.

Heteroatom-doped porous carbon materials are promising candidates for supercapacitor electrodes, but the simple and low-cost preparation method for heteroatom self-doped carbon, especially derived from biomass, remains a challenge. Herein, we developed a novel strategy that can provide an aerophilic interfacial reaction to produce N, S, P self-doped and oxygen functionalized porous carbon from the outer layer structure of durian peels in facile environment. The obtained porous biochar with N, S, P self-doped and abundant oxygen-containing functional groups can enhance the electrochemical capacitor performance, stability, and hydrophilicity of carbon electrode. When employed into symmetric supercapacitor device, the biochar of functionalization could deliver a specific capacitance of 158.20 F g−1 at 1 A g−1, a high energy density of 21.97 Wh kg−1 at a power density of 500 W kg−1 within a voltage window of 1.0 V and a remarkable cycling durability with 101.35% after 20,000 charge/discharge cycles at 4 A g−1 in 6 M KOH electrolyte. This work provides an effective and economic approach to obtain heteroatom self-doped and highly stable carbon-based electrode materials.

This paper presents an easy-to-use, power-free, and modular pump for portable microfluidic applications. The pump module is a degassed particle desorption polydimethylsiloxane (PDMS) slab with an integrated mesh-shaped chamber, which can be attached on the outlet port of microfluidic device to absorb the air in the microfluidic system and then to create a negative pressure for driving fluid. Different from the existing monolithic degassed PDMS pumps that are generally restricted to limited pumping capacity and are only compatible with PDMS-based microfluidic devices, this pump can offer various possible configures of pumping power by varying the geometries of the pump or by combining different pump modules and can also be employed in any material microfluidic devices. The key advantage of this pump is that its operation only requires the user to place the degassed PDMS slab on the outlet ports of microfluidic devices. To help design pumps with a suitable pumping performance, the effect of pump module geometry on its pumping capacity is also investigated. The results indicate that the performance of the degassed PDMS pump is strongly dependent on the surface area of the pump chamber, the exposure area and the volume of the PDMS pump slab. In addition, the initial volume of air in the closed microfluidic system and the cross-linking degree of PDMS also affect the performance of the degassed PDMS pump. Finally, we demonstrated the utility of this modular pumping method by applying it to a glass-based microfluidic device and a PDMS-based protein crystallization microfluidic device.