The microbial impact on waterlogged wooden cultural relics fromXiaobaijiao No. 1shipwreck was investigated by means of a high-throughput sequencing technology, while the focus was on the composition of prokaryotic microorganisms in 10 wood samples collected from different parts of the shipwreck. A total of 28 501 different operational taxonomic units (OTUs) were obtained based on 97% sequence similarity. The α-diversity index is for the bacterial diversity, which was the highest and the lowest in the samples SS8 and SS5, respectively. Proteobacteria was the largest category of bacterial abundance (47.3%) followed by Bacteroidetes (10%). α-Proteobacteria was the first largest bacteria class with the maximum abundance (21.0%) followed by γ-Proteobacteria (16.9%). Other groups rich in the following species were found: Bacteroidales (13.3%), Thiotrichales (5.0%), Rhodobacterales (4.2%), Rhizobiales (4.0%), Chromatiales (3.5%), Oceanospirillales (3.3%), Flavobacteriales (2.9%) and Sphingomonadales (2.8%). At the level of the bacterial genus,Marinomonaswas the most abundant one. Phylogenetic analysis revealed that there are some differences in the composition of bacterial communities from different wood samples. The species number of bacteria in the relics of this shipwreck was far more than that reported in those found in Europe, and in which species composition was similar to the benthic bacteria in the corresponding sea area. The coexistence of anaerobic and aerobic bacteria is remarkable.
Tabia is one of the most widely used construction materials in ancient China. In this work, the tabia samples from three coastal defense fort sites at Zhejiang Province, China, we analyzed to determine their component composition and physiochemical properties. The results show that these tabia samples exhibited high compressive strength, which could be as high as 4–9 MPa. Furthermore, the systematic analysis demonstrated that the high compressive strength was related to the following factors: (1) a suitable mass ratio of sand, lime, and clay; (2) an appropriate sand particle size ratio; and (3) the formation of hydrated calcium silicate (C-S-H). Moreover, sticky rice was also detected in the tabia samples. These findings are fundamentally important, which could be beneficial to further study of the craftsmanship of the coastal defense forts and could further provide essential guidance for the protection and restoration of the tabia relics.
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