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Complex physical–chemical interactions between clay particles including the van der Waals force control the macroscopic behaviors of clay. The calculation of van der Waals force is essential in the discrete element method (DEM) that has been widely used to enhance the understanding of the behavior of clay. Due to its high computational efficiency, a plate-wall model developed in the literature was adopted to obtain the van der Waals force between the neighboring clay particles approximately in the published DEM simulations. However, different choices of the ideal wall result in different magnitudes as well as directions of total van der Waals forces. To investigate the effect, a new rigorous plate-plate model was put forward and solved using an optimized Cotes integration method. Based on the comparison between the calculated results based on plate-wall and plate-plate model, the above effect was analyzed for the cases of face-face, edge-edge and edge-face contact types. Then, necessary advice for the reasonable use of the ideal-wall model was given accordingly.

Optimal reinsurance problems under the risk measures, such as Value-at-Risk (VaR) and Tail-Value-at-Risk (TVaR), have been studied in recent literature. However, losses based on VaR may be underestimated and TVaR allows us to account better for catastrophic losses. In this paper, we propose a new family of flexible risk measures denoted by LVaR , which is a weighted combination of VaR and TVaR. Based on the new risk measures, we deal with the optimal reinsurance problem by minimizing the LVaR of the total risks of an insurer when two types of constraints for reinsurer's risk exposure are considered. The results indicate that the two-layer reinsurance is always an optimal reinsurance policy with both types of constraints. Also, we find that the optimal reinsurance policy depends on the confidence level, the weight coefficient, the safety loading, the tolerance level, as well as the relations between them. Finally, we illustrate the results by numerical examples and compare them with the results in Lu et al. [ABSTRACT FROM AUTHOR]

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The order Oedogoniales comprises three genera, Oedogonium, Oedocladium and Bulbochaete, which were classified based on traditional morphological criteria, and includes more than 600 described species. This group is economically important in astaxanthin production and the energy sector. However, only one mitochondrial genome (mitogenome) has been reported so far. This study determined the mitochondrial genomes of seven Oedogoniales species, including six Oedogonium species and Oedocladium prescottii. Comparative analyses between the newly determined mitogenomes and the previously reported Bulbochaete rectangularis var. hiloensis mitogenome showed that all eight mitogenomes comprised 12 protein-coding genes (PCGs) and two rRNAs; however, the mitogenomes differed in their genome sizes, GC content, tRNAs, non-coding regions and introns. Synteny analysis of the eight mitogenomes revealed a high degree of syntenic conservation in general, with some rearrangements and inversions. The average nucleotide identity (ANI) analysis of the eight mitogenomes indicated Oedogonium dentireticulatum showed high similarity with Oedogonium sp3 (ANI of 96.32%). Most of the PCGs of the eight mitogenomes presented the conventional start codon ATG and stop codon TAR (TAA/TAG/TGA), and the synonymous codon preferences were conserved. Phylogenetic results indicated that Oedogonium was polyphyletic, and species of Oedocladium clustered with Oedogonium, while the position of B. rectangularis var. hiloensis was uncertain for the incongruent phylogenetic results. Statistical analyses of substitution rates demonstrated no significant differences among the three genera, and the dN/dS ratios based on branch model showed that cob, cox1 and nad4 of Oedocladium prescottii and B. rectangularis var. hiloensis were putative fast-evolving genes. These findings suggested that the traditional taxonomy of Oedogoniales did not define natural groups, and that species of Oedocladium and Bulbochaete may have undergone rapid evolution. [ABSTRACT FROM AUTHOR]