To achieve clean and high-quality spinach production, the effects of daily light integral (DLI) and light spectrum on growth, nutritional quality, and energy yield of hydroponic spinach (Spinacia oleracea L.) were investigated in a closed plant factory under light-emitting diode (LED) lighting. The hydroponic spinach plants were grown under 16 combinations of four levels of DLI (11.5, 14.4, 17.3, and 20.2 mol m⁻² day⁻¹) with four light spectra: LED lamps with ratio of red light to blue light (R:B ratio) of 0.9, 1.2, and 2.2 and fluorescent lamps with R:B ratio of 1.8 as control. The results show that total fresh and dry weights, energy yield, and light energy use efficiency (LUE) of harvested spinach were higher under D17.3-L1.2 treatment compared to other treatments. The higher net photosynthetic rates were shown at DLI of 17.3 mol m⁻² day⁻¹ regardless of light quality. Higher vitamin C contents of spinach in all LED treatments were obtained compared with the control. L1.2 treatments with higher fraction of blue light led to more vitamin C content, lower nitrate content, and higher LUE independent of DLI. L2.2 treatment with more fraction of red light was beneficial to reduce oxalate accumulation. Power consumption based on increased total fresh weight under LED lamps with R:B ratio of 1.2 in different DLIs was over 38% lower than that under the fluorescent lamps and 1.73 kWh per 100 g FW at DLI of 17.3 mol m⁻² day⁻¹. In conclusion, lighting environment in DLI of 17.3 mol m⁻² day⁻¹ using LED lamps with R:B ratio of 1.2 is suggested for the design of a LED plant factory for hydroponic spinach production.

Effects of light intensity and LED spectrum on the medicinal component accumulation of hydroponic Hypericum perforatum L. under controlled environments

Simultaneous recovery of waste heat and water from stripped gas streams in CO ₂ chemical absorption is vital for lowering energy penalties. This study reports a novel class of wettability patterned ceramic membranes fabricated via spray-coating commercial hydrophilic substrates with geometrically tailored “window-lattice” hydrophobic patterns and multi-segment wettability gradients. Topological optimization revealed that increasing the pattern count of hydrophobic domains, extending the hydrophilic-hydrophobic boundary length, and tailoring the hydrophobic pattern geometry were beneficial for enhancing heat recovery performance. The tailored membranes achieved a peak heat recovery flux of 22.1 MJ/(m ² ·h) and a specific heat recovery potential of 853.2 kJ/kg, outperforming the initial hydrophilic membrane by 15.6% and 14.2%, respectively. Furthermore, developing stepwise two-segment and three-segment surface wettability gradients imparted a continuous driving force for directional condensate pumping, delivering a water flux of 18.8 kg/(m ² ·h), representing a 42.1% enhancement over the hydrophilic membrane. However, the wettability gradient also introduces additional interfacial thermal resistance and promotes gas-filled pore states, thereby constraining overall heat recovery performance. The design of “window-lattice” ceramic membranes offers new strategies and guidelines for efficient water and heat recovery in membrane condensers, which can be applied to humid gases such as stripped gas, flue gas and biogas, thereby offering sustainable pathways for low energy CO ₂ separation, water reclamation, and energy savings.