ABSTRACT
Rapid development of smart technologies poses a big challenge for magnetostrictive materials, which should not only permit isotropic and hysteresis-free actuation (i.e., non-hysteretic volume change) in magnetic fields, but also have high strength and high ductility. Unfortunately, the magnetostriction from self-assembly of ferromagnetic domains is volume-conserving; the volume magnetostriction from field-induced first-order phase transition has large intrinsic hysteresis; and most prototype magnetostrictive materials are intrinsically brittle. Here we report a magnetic high-entropy alloy (HEA) Fe35Co35Al10Cr10Ni10 that can rectify these challenges, exhibiting an unprecedented combination of large non-hysteretic volume magnetostriction, high tensile strength and large elongation strain, over a wide working temperature range from room temperature down to 100 K. Its exceptional properties stem from a dual-phase microstructure, where the face-centered-cubic (FCC) matrix phase with nano-scale compositional and structural fluctuations can enable a magnetic-field-induced transition from low-spin small-volume state to high-spin large-volume state, and the ordered body-centered-cubic (BCC) B2 phase contributes to mechanical strengthening. The present findings may provide insights into designing unconventional and technologically-important magnetostrictive materials. This article is protected by copyright. All rights reserved.
ABSTRACT
Metal-based nanocatalysts supported on carbon have significant prospect for industry. However, a straightforward method for efficient and stable nanocatalysts still remains extremely challenging. Inspired by the structure and comptosition of cell walls and membranes, an ion chemical bond anchoring, an in situ carbonization coreduction process, is designed to obtain composite catalysts on N-doped 2D carbon (C-N) loaded with various noble and non-noble metals (for example, Pt, Ru, Rh, Pd, Ag, Ir, Au, Co, and Ni) nanocatalysts. These 2 nm particles uniformly and stably bond with the C-N support since the agglomeration and growth are suppressed by anchoring the metal ions on the cell wall and membrane during the carbonization and reduction reactions. The Pt@C-N exhibits excellent catalytic activity and long-term stability for the hydrogen evolution reaction, and the relative overpotential at 100 mA cm-2 is only 77 mV, which is much lower than that of commercial Pt/C and Pt single-atom catalysts reported recently.
ABSTRACT
The molluscicide niclosamide is found in most of the wetlands of China. The migration and transformation pathways, and degradation kinetics of niclosamide in the plant-soil system was analyzed by with the use of potting experiment. Experimental results showed that degradation of niclosamide in rhizosphere soil fit the first-order kinetics, and microorganisms played an important role in the degradation of niclosamide. It was found that niclosamide degrades to form a series of aromatic intermediate products both in soil and plants. Niclosamide could be absorbed from soil to plant by the root and then migrate to the stem. At an initial concentration of niclosamide of 2.11 mg·kg-1 in soil, the maximum residue of niclosamide in Artemisia somai aerial was 2.47 mg·kg-1 after 10 days of cultivation. This value is close to the pollution maximum residue limit (3 mg·kg-1) in rice, and niclosamide and its intermediates can remain about 43 days in plants. The experimental results demonstrate that the use of niclosamide in wetlands would have some risk in edible plants and was harmful for human health.
ABSTRACT
The purpose of this study was to develop a method to prepare Metoprolol Succinate (MS) sustained release pellets and compress them into pellet-containing tablets without losing sustained release property. The drug layered pellets were coated with Eudragit NE 30D to obtain a sustained release (SR) property. The mechanical properties and permeability of the coating film were tailored by adjusting the proportion of talc in the coating dispersion and the weight gain of the coating film. Pellets with different MS release rates were tested and then mixed together by different ratios to optimize drug release rate. The mixed pellets were compressed into tablets with cushioning excipients. The results showed that when the ratio of talc and coating material was 1:4, the coating operation could be conducted successfully without pellet conglutination and the mechanical property of the coating film was enhanced to withstand the compress force during tableting. Blending SR-coated pellets of 20% weight gain with SR-coated pellets of 40% weight gain at the ratio of 1:5 could produce a constant and desired drug release rate. The formulation and the procedure developed in the study were suitable to prepare MS pellet-containing tablets with selected SR properties.
