Experimental Investigation on Interface Performance of UHPC-Strengthened NC Structure through Push-Out Tests.

Strengthening concrete structures with ultra-high performance concrete (UHPC) can both improve the bearing capacity of the original normal concrete (NC) structure and prolong the service life of the structure due to the high strength and durability of UHPC. The key to the synergistic work of the UHPC-strengthened layer and the original NC structures lies in the reliable bonding of their interfaces. In this research study, the shear performance of the UHPC-NC interface was investigated by the direct shear (push-out test) test method. The effects of different interface preparation methods (smoothing, chiseling, and planting straight and hooked rebars) and different aspect ratios of planted rebars on the failure mode and shear performance of the pushed-out specimens were studied. Seven groups of push-out specimens were tested. The results show that the interface preparation method can significantly affect the failure mode of the UHPC-NC interface, which is specifically divided into interface failure, planted rebar pull-out, and NC shear failure. The critical aspect ratio for the pull-out or anchorage of planted rebars in UHPC is around 2. The interface shear strength of straight-planted rebar interface preparation is significantly improved compared with that of the chiseled and smoothened interfaces, and as the embedding length of the planted rebar becomes longer, it first increases greatly and then tends to be stable when the rebar planted in UHPC is fully anchored. The shear stiffness of UHPC-NC increases with the increase of the aspect ratio of planted rebars. A design recommendation based on the experimental results is proposed. This research study supplements the theoretical basis of the interface design of UHPC-strengthened NC structures.

Complete chloroplast genome sequence of Nicotiana tabacum TN90 (Solanaceae).

This study reported the complete nucleotide sequence of the Nicotiana tabacum TN90 chloroplast (cp) genome. The cpDNA was 155 992 bp in length and contained 133 individual genes (79 protein encoding genes, 30 tRNA genes and four rRNA genes). Maximum-likelihood (ML) phylogenetic tree for 17 species with Arabidopsis thaliana, Oryza sativa, and Anomochloa marantoidea as an outgroup resulted in a single tree with - lnL =542 222.71, where the Nicotiana tabacum TN90 plastid was clustered with three previous reported Nicotiana species: N. tomentosiformis, N. undulata and N. tabacum. The TN90 variety of tobacco cp genome sequence reported in this study will accelerate tobacco improvement in the future.