Search

Catalytic reduction of 4-nitrophenol (4-NP) into 4-aminophenol (4-AP) is an important method for treating toxic nitroaromatic pollutant. In this work, amorphous CoSn(OH)6 nanocubes were synthesized by coprecipitation and calcination methods for 4-NP photocatalytic reduction. The crystal structure, morphology and optical property of the samples were characterized by XRD, SEM, TEM, XPS, and UV–vis DRS. The amorphous CoSn(OH)6 nanocubes showed excellent photocatalytic performance in 4-NP reduction. The effects of catalyst dosage, 4-NP concentration, and sodium borohydride concentration on the conversion rate of 4-NP were investigated. The results showed that the conversion rate of 4-NP could reach 98.38% in 15 min at room temperature under visible light irradiation. After five cycles of experiments, the conversion rate of 4-NP remained above 90%, indicating the good catalytic stability of the amorphous CoSn(OH)6 nanocubes. Finally, the mechanisms of photocatalytic reduction on amorphous CoSn(OH)6 nanocubes are also discussed. The successful preparation of amorphous CoSn(OH)6 nanocubes may enable the widespread use of amorphous polymetallic oxides for the removal of nitrophenols from wastewater in the future. Highlights: Amorphous CoSn(OH)6 nanocubes were synthesized without using any surfactant after calcining in argon at 300 °C; Amorphous CoSn(OH)6 nanocubes show the narrower bandgap than that of CoSn(OH)6 nanocrystals. Amorphous CoSn(OH)6 nanocubes exhibit superior photocatalytic reduction 4-NP to 4-AP performance. [ABSTRACT FROM AUTHOR]

Ginseng rusty root symptoms (GRS) is a primary disease of ginseng, which seriously decreases the yield and quality of ginseng and causes enormous losses to ginseng production. GRS prevention and control is still challenging due to its unclear etiology. In this study, the phloem tissue of healthy Panax ginseng (AG), the nonred tissue of the phloem epidermis around the lesion (BG), and the red lesion site tissue of GRS (CG) were extracted for mRNA transcriptomic analysis; 35,958 differentially expressed genes (DEGs) were identified and were associated with multiple stress resistance pathways, reactive oxygen species (ROS), and iron ion binding. Further study showed that the contents of O2•‐, H2O2, and malondialdehyde (MDA) were significantly increased in BG and CG tissues. Under anaerobic conditions caused by excessive soil moisture, the overproduction of ROS destroys cell membranes, simultaneously converting Fe2+ to Fe3+ and depositing it in the cell wall, which results in GRS, as evidenced by the success of the GRS induction test. [ABSTRACT FROM AUTHOR]

The problem of robust, angular velocity-free control and fault-tolerant control for liquid-filled flexible spacecraft attitude maneuver subject to unknown external disturbances is investigated. Moreover, state variables measurement uncertainty and actuator failures are explored. The liquid sloshing effect of spacecraft fuel is equivalent to a two-order spring-mass model, and the flexible attachments are equivalent to the Euler–Bernoulli beams. The external disturbance, multiple failures of the output actuator, and the coupled interference caused by liquid sloshing and vibrations of flexible attachments are distinguished as continuous and percussive disturbances. First, a fault-tolerant control method against the percussive disturbances is proposed, and the robustness performance and characteristics of this method are analyzed. Then, both continuous and percussive disturbances are considered to propose a new fault-tolerant control method based on a nonlinear disturbance observer, which is used to estimate the integrated disturbance. The Lyapunov stability theory proves that the proposed control strategy can make the state variables converge to a small neighborhood of the origin in finite time. Finally, the numerical simulation is used to verify the effectiveness and robustness of the proposed control strategy. [ABSTRACT FROM AUTHOR]

Currently, the predominant thermal insulation materials in the construction industry are primarily derived from inorganic sources. While these materials demonstrate commendable thermal insulation capabilities, their widespread use raises significant environmental concerns. The utilization of wood fiber materials presents a promising solution to mitigate these drawbacks. This study focuses on the fabrication of biodegradable fiber insulation board (BFIB) using camphor branches. The manufacturing process avoids the use of chemical additives, employing a physical method that utilizes hot pressing and relies on the formation of intermolecular hydrogen and hydroxide bonds between the fibers. The study evaluates the influence of applied pressure on the properties of BFIB. SEM images reveal that, with an increase in applied pressure, the fibers exhibit a more regular pattern, subsequently enhancing the mechanical properties, hygric behavior, and fire resistance properties of BFIB. As an environmentally friendly and renewable material, BFIB holds the potential to substitute conventional insulation materials. It is particularly intriguing for energy-saving purposes when applied as building insulation for walls or ceilings. [ABSTRACT FROM AUTHOR]