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To evaluate influence of blast vibrations on the long-term mechanical deterioration and damage anisotropy of fresh concrete, blast vibration tests were conducted by preparing concrete test blocks at different curing ages. On this basis, the internal relationships of factors including the curing age during vibrations, vibration blast velocity, and number of blast vibrations with the damage evolution were investigated. The results show that fresh concrete is more susceptible to blasting vibration in the initial setting stage, which changes the bonding performance between cementing materials and aggregates. Then irreversible damage is generated along the main direction of vibration, and cumulative damage occurs with the increasing number of blast vibrations. Fresh concrete was affected most by blasting vibration at an age of 1 day, and the compressive strength at 28 days was reduced by 44.17% under a single vibration event. The damage increased slowly in the concrete at curing ages from 1 to 7 day. Blast vibrations with a velocity of less than 96.2 mm/s had a slight influence on changes in the compressive strength of concrete cured for 28 days. As the blast vibration velocity increased from 96.2 to 180.6 mm/s , the decrease rate of compressive strength in various directions accelerated and the strength decreased by as much as 40.59%. Therefore, it is suggested that the influence of the blast vibration velocity and the number of blast vibrations should be considered in alternating and parallel construction of blasting and concrete pouring work. Furthermore, blast vibration velocity, number of blast vibrations, and maximum attenuation coefficients of longitudinal wave velocities of vibrated concrete test blocks with the same curing age during vibrations differed along three directions, showing anisotropic characteristics. As the velocity and number of blast vibrations increased, the damage anisotropy became more significant. Therefore, the influence of anisotropy of cumulative damage evolution should be considered when establishing the safety criteria for fresh concrete subjected to blast vibrations. [ABSTRACT FROM AUTHOR]

To improve the secretion mass fraction of tobacco glandular trichomes, a homozygous mutant plant TTB-1 (tobacco trichome bioreactor-1) was obtained by using gene editing technology to remove NtCycB2, a negative regulatory gene of glandular trichome development, in T.I.1068 germplasm. The results showed that TTB-1 plants grew vigorously and developed normally. Unlike the flue-cured tobacco cv. K326, the surface fur of TTB-1 and T.I.1068 was composed of glandular trichomes without protection. The glandular trichome density of TTB-1 was 53.41% higher than that of T.I.1068 and 7 times higher than that of K326. Compared to K326, the TTB-1 glandular head was fuller and Rhodamine staining was darker. The test results of the chemical components on the leaf surface of the middle leaves of tobacco plants at the bud stage indicated that the components in TTB-1 and T.I.1068 secretions were consistent, but the content of secretions was significantly higher in TTB-1, and its total secretion amount was 63.11% higher than that of T.I.1068. The secretions of TTB-1 differed from those of K326. In addition to cembranoid diterpene and type I-II sucrose esters, TTB-1 also contained labdane diterpene and type III-V sucrose esters, and its total secretion amount was 7.95 times of that of K326. The mature upper, middle and lower leaves were harvested in batches and the chemical components on the leaf surfaces were extracted. The concrete yield was 0.61%, 0.43%, and 0.30% of the fresh upper, middle, and lower leaf weights, respectively, and the average concrete yield per plant was 8.90 g. The concrete yield was 0.45% of the fresh leaf weight, and the average concrete yield per plant was 8.06 g when harvesting by one-priming at flowering stage. [ABSTRACT FROM AUTHOR]