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The self-healing materials have become more and more popular due to their active capacity of repairing the (micro-) damages, such as the (micro-) cracks, the (micro-) voids and the other defects. In this paper, the thermodynamic based damage-healing framework is presented for the hydration induced self-healing composite with a compatible healing variable. The new variable is incorporated to consider the time-dependent properties of the hydration products, with which a new damage healing law is proposed. The hydration kinetics are employed to describe the healing process. The properties of the hydration products are arrived with the multiscale and multilevel homogenization scheme. The presented damage-healing model is applied to an isotropic cementitious composite under the tensile loading histories. The presented framework is compared with the classic continuum damage-healing theory and the experimental data. The results show that the presented damage-healing model is capable of describing the hydration induced self-healing of the cementitious composite. It can describe the behavior of the partially and fully healed concrete material. The effects of the healing time and the compatible healing variables on the damage-healing results are investigated based on our proposed framework.

The excellent performance of PMN–PT has received increasing attention and applications in high-frequency (>20 MHz) ultrasonic array transducers. However, due to its brittleness and low phase-transition temperature of PMN–PT, a decrease of piezoelectric properties in the fabrication of small-scale array elements is still an urgent problem and would substantially determine the performance of transducers. Here, in this study, ultrashort pulse laser technique is proposed to fabricate PMN–PT array transducers with outstanding performance. The effect of the laser parameters on domain structures has been studied systematically, and it was found that the ultrahigh piezoelectric properties of micro-sized elements still maintained after optimizing the laser parameters. A Fresnel array transducer with center frequency of 40.84 MHz and −6dB bandwidth as high as 122.28% was also designed and fabricated. This work demonstrates that it is feasible and promising to fabricate superior PMN–PT and other piezoelectric ultrasonic array transducers based on ultrashort pulse laser techniques.

Biodegradation of wood by fungi and termites is recognized as one of the most serious problems for wooden structures. In this study, we analyzed the antitermitic and antifungal activities of flower buds essential oil from Syzygium aromaticum and its dominant constituents. Essential oil components were analyzed by gas chromatography and the major compound of essential oil was eugenol (90.6%). The results demonstrated that at the dosage of 50 μg/g, clove essential oil had 100% mortality to Reticulitermes chinensis after testing for 5 d. Furthermore, we found eugenol killed all termites after testing for 3 d, with an LC 50 value of 12.1 μg/g. Meanwhile, we also found clove essential oil and eugenol displayed activity against three fungi, Trametes hirsuta , Schizphylhls commne , and Pycnoporus sanguineus . We found eugenol was principal antifungal constituent of clove oil. The IC 50 values of eugenol against T. hirsuta , S. commne , and P. sanguineus were 83.6, 116.1, and 102.4 μg/mL, respectively. In addition, comparisons of the termite mortality and antifungal indices of eugenol and its congeners proved that eugenol exhibited the strongest antitermitic and antifungal activities. The clove oil and eugenol have potential for the development of natural wood preservatives.