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Most self-healing hydrogels always exhibited poor mechanical property which largely limited the applications in many fields. In this work, g-C3N4nanosheets were introduced to the PVA-borax hydrogel to reinforce the network without sacrificing the self-healing ability. The obtained hydrogel displayed remarkable tensile strength (0.98 MPa), Young’s modulus (1.54 MPa) and toughness (4.43 MJ m−3), of which the self-healing efficiency reached to 99 % in 10 min at room temperature. Overall, the strategy proposed in this work provides a simple, operatable and moderate approach to hydrogel with both excellent mechanical property and self-healing ability.

Excess phosphate in water can cause eutrophication, resulting in the destruction of water ecosystems. Phosphate removal has become one of the most important issues in wastewater treatment, and the adsorption is one of the important methods. Bentonite has been widely used for phosphate-containing wastewater treatment due to its low cost and large reserve. However, the unmodified benton-ite usually has a relatively weak phosphate removal ability because of its negatively charge. Here, the lanthanum-modified bentonites were prepared by three methods (impregnation, acidification– impregnation, and ion exchange) in order to improve the phosphate removal capacity. The structures of the lanthanum-modified adsorbents were characterized and the effects of the modification method and adsorption conditions on the phosphate removal were investigated. The results show that the phosphate removal efficiency of the bentonite was increased after the lanthanum modification. In particular, the lanthanum-modified bentonite prepared by impregnating 0.1 mol·L–1La3+solution has the largest pore size and pore volume, which are 7.4 nm and 0.423 cm3·g–1, respectively. This lanthanum-modified bentonite also has the highest phosphate adsorption capacity, which is about 24.9 mg·g–1at the optimal working conditions (initial phosphate concentration of 50 mg·L–1, adsorbent dosage of 2 g·L–1, temperature of 30°C, and pH of 6). The corresponding removal rate is as high as 99.5% in 30 min, while that of the raw bentonite is only about 26.8% in 60 min. The results show that the lanthanum-modified bentonite prepared by impregnation method could be a promising adsorbent for efficient phosphate removal.

With the increasing requirements for the shooting accuracy of the sniper rifle, steel combined with excellent high-temperature strength, low-temperature toughness, and extraordinary corrosion resistance is desirable for the barrel material of the sniper rifle with high accuracy and a long lifespan. In this study, martensitic stainless steel 2Cr11Ni2Mo2WV (MPS700A) was developed by introducing Mo, W, and V into the currently used 2Cr13 steel. The 600 °C tensile tests demonstrated that the ultimate tensile strength of MPS700A reached 767 MPa, which was 46.4 and 97.2 % higher than those of 2Cr13 and 30SiMn2MoV, respectively. Meanwhile, the −40 °C impact toughness of MPS700A reached 88 ± 4 J/cm2, which was 20.5% higher than that of 2Cr13 and comparable to that of 30SiMn2MoV. The intralath precipitation of ellipsoidal M2C nano carbides was observed in MPS700A after tempering, which followed a Dyson orientation relationship (OR) of (01¯12)M2C//(200)αwith the martensitic matrix. After deformation at 600 °C, such a Dyson orientation relationship (OR) was maintained, and the M2C in MPS700A exhibited higher thermal stability than the M3C in 2Cr13, which hinders the dislocation movement and contributes to the higher strength of MPS700A at 600 °C. The fine martensitic laths and homogeneously dispersed M2C nano carbides also contributed to the higher impact toughness of MPS700A than that of 2Cr13. Additionally, the salt spray test indicated that the mass loss of MPS700A was 1.72 ± 0.24 g m−2at 72 h, which was 95.6% lower than that of Cr-plated 30SiMn2MoV and comparable to that of 2Cr13. Based on these results, we demonstrate that MPS700A exhibits high strength up to 600 °C, excellent impact toughness at low temperatures, and outstanding corrosion resistance, making it a promising gun barrel material for sniper rifles with long lifespans and high shooting accuracy.