Search

The supercritical carbon dioxide (S-CO2) power cycle is widely applicable to the utilization of multigrade heat sources due to its high efficiency and compact structure, in which the turbine is critical to the performance of the system. In this study, the operation pattern and output performance of an S-CO2 axial turbine with a design power scale of 10 kW power are investigated by experiments and numerical simulations. The loss mechanisms and distributions are analyzed using numerical simulations and loss models. The results show that the turbine output power and efficiency are at 9.66 kW and 36.6% at the designed condition and the output performance depends on the pressure ratio and rational speed. In addition, the flow field distribution reveals that the flow separation phenomenon occurs leading to loss, with the tip clearance loss being the most significant. Furthermore, the loss model validated in this paper is proven to be competent enough to fulfill the prediction of the loss distribution under different operational conditions, which could be very promising in the design of an S-CO2 axial turbine.

In recent years, stimuli-responsive polymers, a kind of functional material, have drawn increasing attention. In this paper, acrylamide azobenzene was introduced into the molecularly imprinted polymer by copolymerization with acrylic acid in the presence of template molecules methylene blue, crosslinker N,N '‑methylene bisacrylamide, and initiator azobisisobutyronitrile, which makes the imprinting material have the effect of light-operated and further expand the application range of imprinting materials. Detailed studies of the photo-regulated uptake and release process suggested that the binding affinity of imprinted recognition sites in imprinting materials could be changed under the alternating irradiation of ultraviolet and visible light. The adsorption isotherm experiments and adsorption kinetic experiments showed that the adsorption of methylene blue by the imprinted material conforms to the monolayer chemical adsorption and quasi-second-order kinetic model. Additionally, the relevant thermodynamic parameters were calculated. These thermodynamic parameters proved that the adsorption process was spontaneous, endothermic and entropy-increasing.

Cadmium (Cd) contamination in paddy soils means that the rice produced there may be unsafe for human consumption. A hydroponic study was conducted to enrich rice seedlings with zinc (Zn) or manganese (Mn), and the uptake and transport characteristics of Cd in these Zn- and Mn-rich seedlings were subsequently investigated using a greenhouse pot trial. The results showed that hydroponic cultivation in 10–50 µmol L–1 Zn (ZnSO4·7H2O) or 50–250 µmol L–1 Mn (MnSO4·H2O) for 30 d had no significant impact on rice growth, while the accumulation of Zn and Mn was 7.31–18.5 and 25.4–47.7 times higher, respectively, than in the control (no Zn or Mn addition). The accumulation of Cd in the Zn- and Mn-rich rice plants was 26.3%–38.6% and 34.4%–44.5% lower than that in the control, respectively, and the translocation factors of Cd from roots to shoots also decreased by 23.3%–41.3% and 25.3%–37.0%, respectively, after transplanting to Cd-contaminated soils. Furthermore, the relative expression levels of OsIRT1 (Oryza sativa iron-regulated transporter 1) were downregulated by 40.1%–59.3% and 16.0%–25.9%, respectively, in the Zn- and Mn-rich seedling roots. This downregulation may indicate a possible mechanism contributing to the reductions in Cd absorption. Field experiments confirmed that the Zn- and Mn-rich seedlings produced brown rice (unpolished rice grains) with significantly decreased concentrations of Cd (34.2%–44.4%). This study provides an innovative method for reducing the food safety risks from rice grown on slightly to moderately Cd-contaminated paddy soils.