No abstract

Summary Dipterocarpaceae are typical tropical plants (dipterocarp forests) that are famous for their high economic value because of their production of fragrant oleoresins, top‐quality timber and usage in traditional Chinese medicine. Currently, the lack of Dipterocarpaceae genomes has been a limiting factor to decipher the fragrant oleoresin biosynthesis and gain evolutionary insights into high‐quality wood formation in Dipterocarpaceae. We generated chromosome‐level genome assemblies for two representative Dipterocarpaceae species viz. Dipterocarpus turbinatus Gaertn. f. and Hopea hainanensis Merr. et Chun. Our whole‐genome duplication (WGD) analysis revealed that Dipterocarpaceae underwent a shared WGD event, which showed significant impacts on increased copy numbers of genes related to the biosynthesis of terpene, BAHD acyltransferases, fatty acid and benzenoid/phenylpropanoid, which probably confer to the formation of their characteristic fragrant oleoresin. Additionally, compared with common soft wood plants, the expansion of gene families was also found to be associated with wood formation, such as in CESA (cellulose synthase), CSLE (cellulose synthase‐like protein E), laccase and peroxidase in Dipterocarpaceae genomes, which might also contribute to the formation of harder, stronger and high‐density timbers. Finally, an integrative analysis on a combination of genomic, transcriptomic and metabolic data from different tissues provided further insights into the molecular basis of fragrant oleoresins biosynthesis and high‐quality wood formation of Dipterocarpaceae. Our study contributes the first two representative genomes for Dipterocarpaceae, which are valuable genetic resources for further researches on the fragrant oleoresins and superior‐quality timber, genome‐assisted breeding and improvement, and conservation biology of this family.

No abstract

Superabsorbent polymers (SAPs) can effectively reduce the risk of concrete cracks by acting as an internal curing material. In this study, 1 H low-field NMR was used to investigate the influence of the pre-absorbed water amount and the water-cement ratio of paste on the water absorption-release behavior of SAPs in fresh cement paste. Results show that when the water-cement ratio was 0.30, the SAPs without pre-absorption absorbed water from fresh cement paste and retained them with relative stability. The SAPs with pre-absorption would rapidly release the pre-absorbed water into a paste, and the water releasing speed increased with the amount of pre-absorbed water. Additionally, the water amount absorbed by the SAPs without pre-absorption increased with the water-cement ratio from 0.30 to 0.40. However, the water absorption of SAPs from the paste was also found to be severely inhibited when the water-cement ratio reached 0.50. SAP swelling in fresh cement paste is affected by the synergistic effects of multiple ions.

No abstract