Evaluation of Self-Healing Efficiency of Microcapsule-Based Self-Healing Cementitious Composites Based on Acoustic Emission

Microcapsule self-healing technology is one of the effective methods to solve the durability problem of cementbased composites.The evaluation method of the self-healing efficiency of microcapsule self-healing cement-based composites is one of the difficulties that limits the self-healing technology.This paper attempts to characterize the self-healing efficiency of microcapsule self-healing cement-based composites by acoustic emission(AE)parameters,which provides a reference for the evaluation of microcapsule self-healing technology.Firstly,a kind of self-healing microcapsules were prepared,and the microcapsules were added into the cement-based composites to prepare the compression samples.Then,the specimen with certain pre damage was obtained by compression test.Secondly,the damaged samples were divided into two groups.One group was directly used for compression tests to obtain the damage failure process.The other group was put into water for healing for 30 days,and then compression tests were carried out to study the influence of self-healing on the compression failure process.During the experiments,the AE signals were collected and the AE characteristics were extracted for the evaluation of self-healing efficiency.The results show that the compression pre damage test can trigger the microcapsule,and the compression strength of the self-healing sample is improved.The failure mechanism of microcapsule selfhealing cement-based composites can be revealed by the AE parameters during compression,and the self-healing efficiency can be quantitatively characterized by AE hits.The research results of this paper provide experimental reference and technical support for the mechanical property test and healing efficiency evaluation of microcapsule self-healing cement-based composites.

Chemical constituents from the fruit of Schisandra Chinensis

A new 18-norschiartane bisnortriterpenoid,12-angeloyl wuweizidilactone I(1)and nine known compounds,wuweizidilactone I(2),wuweizidilactone G(3),deoxychizandrin(4),sasanquin(5),orcinol-O-β-D-glucopyranoside(6),okanin-4-methyl ether-3’-O-β-Dglucopyranoside(7),evemic acid(8),juglansol A(9)and 2-acetoxybenzyl benzoate(10),were isolated from the fruits of Schisandra Chinensis.Their structures were established by a combination of spectroscopic data analysis in addition to comparison with literature data.Compound 1 was new,and compounds 6–10 were isolated from Schisandrae Chinensis for the first time.

Soft X-ray in-line holographic experiment

Water window" soft X-ray has some advantages in the microimaging of biological specimens. Soft X-ray holography can give us three-dimensional images of biological cells in their natural condition. Quasi-monochromatic soft X-ray from the polymonochromatic synchrotron radiation is obtained by a zone plate-pinhole linear monochromator at National Synchrotron Radiation Laboratory (NSRL) at Hefei. The pinhole is used to increase the temporal coherence of the soft X-ray, and also to increase the spatial coherence of it. An in-line holographic experiment has been finished with soft X-ray of main wavelength 4.5 nm and pinhole of diameter 0.03 mm. The magnified hologram is reconstructed with He-Ne laser. A smaller pinhole is wanted to be used to improve the coherence of the soft X-ray so as to improve the quality of the hologram.