Hospital-acquired infections are a serious threat to the recovery of patients. To prevent such infections, an antibacterial coating is an effective method to eliminate bacterial colonization on healthcare-related surfaces. Herein, we report an antibacterial hydrogel composed of silver-containing polyoxometalate (AgP5W30 POM) and carboxymethyl chitosan (CMC). The silver ion is encapsulated inside the POM cage and demonstrates long-lasting bacteriostasis after repeated exposure to both Gram-positive and Gram-negative bacteria. The chemical structure of chitosan derivatives, as well as the concentration and pH, is studied to tune the mechanical properties of the hydrogel. The hydrogel undergoes a gel–sol transition above the critical temperature and possesses self-healing ability. This hydrogel can be readily coated on the surface of versatile bulk materials, which is especially convenient for porous objects and resists the growth of Staphylococcus aureus, Escherichia coli, and methicillin-resistant S. aureus (MRSA). In summary, we envision that the AgP5W30-CMC hydrogel has great potential to serve as an antibacterial coating to decrease the prevalence of hospital-acquired infections.

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The phase transformation behavior of anatase and rutile titanium dioxide with particle sizes of 60 nm and 150 nm under shock compression have been investigated. To increase the shock pressure and reduce the shock temperature, copper powder and a small amount of paraffin were mixed with the TiO powder. The shock recovered samples were characterized by x-ray diffraction, Raman spectroscopy, and transmission electron microscope. The results indicate that both anatase and rutile TiO can transform to α-PbO phase TiO through shock-induced phase transition. The transformation rate of α-PbO phase TiO for anatase TiO under shock compression is 100% and pure α-PbO phase TiO can be obtained, while the transformation rate for rutile TiO is over 90%. The influence of the particle size on the yield of α-PbO phase TiO is not noticeable. The thermal stability of the recovered pure α-PbO phase TiO was characterized by high temperature x-ray diffraction, thermogravimetric analysis and differential scanning calorimetry. The results show that α-PbO phase TiO transforms to rutile TiO when heated to temperature higher than 560 °C. The mechanisms of the phase transition of TiO under shock compression are discussed.

Abstract. The TiSi 2 and Ti 5 Si 3 compounds with different Ti/Si ratios were synthesized by shockinduced reaction arisen from the flyer impact driven by detonation of the main charge of nitromethane. The phase composition and particle morphology of the recovered samples were characterized by XRD and SEM. It is found that TiSi 2 is formed while flyer velocity is at 3.37km/s and exhibits certain photocatalytic activity of splitting water into hydrogen compared with the unreacted Ti+Si precursor shocked at 3.07km/s. Consequently, Ti 5 Si 3 synthesized at 3.37km/s has much better photocatalytic activity of splitting water into hydrogen than that of TiSi 2 synthesized by shock wave at identical condition. The coupled photocatalyst of Ti 5 Si 3 and Ti 8 O 15 were shocksynthesized by adding oxidant of NH 4 ClO 4 (wt.5%) and exhibits superior photocatalytic activity. The experimental results suggest that shock-induced reaction of Ti and Si with different ratios or other reagent may get novel functional materials for photocatalytic or photovoltaic application.