[en] In order to explore effects of cadmium stress on the growth and development of pecan seedling, pecan seedling was used as testing material, nutrient solution culture method was adopted and the physiological indexes of pecan seedlings were measured under different concentration of cadmium [0 (CK), 5, 10, 20, 40, 80 mg · L^-1]. The results showed that cadmium stress has a significant inhibitory effect on the growth and development of pecan. The inhibitory effect is more obvious with higher concentration of cadmium. With the increase of the cadmium concentration, biomass and root length decreased significantly, which decreased by 40.11% and 56.64% compared with the control group at the concentration of 80 mg · L^-1. The cadmium content in roots, stems and leaves of seedlings rose significantly, and reached 5582 mg · kg^-1, 2235 mg · kg^-1, 479 mg · kg^-1 at the concentration of 80 mg · L^-1. The contents of Mn, Zn, Mg and K in roots and stems were inhibited, but the contents of K and Mg in leaves increased significantly. When the concentration of cadmium was 20 mg · L^-1, the activity of POD and CAT in leaves reached the highest level, and increased by 726.62%, 86.47% compared with the control group. At the concentration of 20 mg · L^-1, the net photosynthetic rate (Pn), stomatal conductance (Gs) and transpiration rate (Tr) of leaves dropped dramatically by 81.44%, 81.59% and 75.22% compared with the control group, respectively. And leaf fluorescence parameters-efficiency of primary conversion of light energy (ΦPSII), apparent electron transfer rate (ETR) and photochemical quenching (qP) decreased significantly while non-photochemical quenching (qN) increased significantly, and photosynthesis was severely inhibited. To sum up, cadmium stress inhibited the biomass accumulation of pecan seedlings and affected the absorption of elements in roots and stems, and significantly reduced the photosynthesis intensity of leaves, causing serious damage to seedling growth. This study laid the foundation for revealing the cadmium tolerance and cadmium enrichment mechanism of pecan. (authors)

[en] Highlights: • Li atoms prefer to be adsorbed at the V-site in both pure monolayer P and SWBPNT. • Compared with the outside, the inside of SWBPNT is a fast diffusion channel for Li. • As the number of Li atoms increases, they still prefer to be adsorbed inside SWBPNT. • The study suggest that SWBPNT can be used in Li-ion batteries as anode base material. Based on first principles calculations, the possibility of zigzag single-walled blue phosphorene nanotube (SWBPNT) as anode materials for high-performance lithium-ion batteries is studied. We calculate the adsorption, diffusion properties and cell voltages of lithium intercalation on the inside and outside of SWBPNT and compare them with those in carbon nanotube (CNT) and single-walled Si nanotube (SWSiNT). The results show that the inside of SWBPNT is a fast diffusion channel of lithium compared with the outside of SWBPNT. By calculating the structure parameters, adsorption energy and charge transfer, we study the adsorption of multiple lithium atoms in SWBPNT. The results show that lithium is easier to diffuse and adsorb inside the tubes, which will help to improve the lithium storage capacity of the system. Therefore, SWBPNT has great potential as anode materials for Li-ion batteries.

[en] Rod-shaped active micro/nano-particles, such as bacterial and bipolar metallic micro/nano-motors, demonstrate novel collective phenomena far from the equilibrium state compared to passive particles. We apply a simulation approach --dissipative particle dynamics (DPD)-- to explore the collectively ordered states of self-propelled rods (SPRs). The SPRs are confined in a finite circular zone and repel each other when two rods touch each other. It is found that for a long enough rods system, the global vortex patterns, dynamic pattern oscillation between hedgehog pattern and vortex pattern, and hedgehog patterns are observed successively with increasing active force F_a. For the vortex pattern, the total interaction energy between the rods U is linear with active force F_a, i.e., U ∼ F_a . While the relation U ∼ F_a² is obtained for the hedgehog structure. It is observed that a new hedgehog pattern with one defect core is created by two ejections of polar cluster in opposite directions from the original hedgehog pattern, and then merges into one through the diffusion of the two aggregates, i.e., the creation and annihilation of topological charges. Graphical abstract:

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