The Stiffness Behavior of Asphalt Mixtures with Different Compactness under Variable Confinement.

The dynamic modulus is a key property determining the short- and long-term performance of asphalt pavement, and its strong dependence on confining pressure and material density (mixture compactness) has been clearly indicated in the literature. It is always challenging to reproduce three-dimensional in situ stress conditions in the laboratory. To alleviate this difficulty, in this study, a convenient experimental setup was developed, in which the lateral confinement was made present and variable as a concomitant reaction of the surrounding materials to the vertical loading. Three dense-graded mixtures were prepared to a set of four different densities and then subjected to the confined dynamic modulus test. The results indicated a significant dependence of the confined modulus on the three factors of temperature, frequency, and compactness and that the mixture with coarser gradation demonstrated a less sensitivity to these parameters. A mathematical model was developed for the dynamic modulus master curve unifying these factors by means of horizontal shifting due to the time-temperature superposition principle (validated against the variable confinement at different compactness) and the vertical shift factor as a function of reduced frequency and compactness. The adequacy of the model was demonstrated using the experimental data, and its potential application in field pavement compaction was discussed.

Phylogeny and genetic variations of the three genome compartments in haptophytes shed light on the rapid evolution of coccolithophores.

Haptophyte algae, including coccolithophores, play key roles in global carbon cycling and ecosystem. They exhibit exceptional morphological and functional diversity. However, their phylogeny is mostly based on short markers and genome researches are always limited to few species, hindering a better understanding about their evolution and diversification. In this study, by assembling 69 new plastid genomes, 65 new mitochondrial genomes, and 55 nuclear drafts, we systematically analyzed their genome variations and built the most comprehensive phylogenies in haptophytes and Noelaerhabdaceae, with the latter is the family of the model coccolithophore Emiliania huxleyi. The haptophyte genomes vary significantly in size, gene content, and structure. We detected phylogenetic incongruence of Prymnesiales between genome compartments. In Noelaerhabdaceae, by including Reticulofenestra sessilis and a proper outgroup, we found R. sessilis was not the basal taxon of this family. Noelaerhabdaceae strains have very similar genomic features and conserved sequences, but different gene content and dynamic structure. We speculate that was caused by DNA double-strand break repairs. Our results provide valuable genetic resources and new insights into the evolution of haptophytes, especially coccolithophores.