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Background Chloroplast (cp) genomes are generally considered to be conservative and play an important role in population diversity analysis in plants, but the characteristics and diversity of the different germplasm populations in Japanese apricot are still not clear. Results A total of 146 cp genomes from three groups of wild, domesticated, and bred accessions of Japanese apricot were sequenced in this study. The comparative genome analysis revealed that the 146 cp genomes were divided into 41 types, and ranged in size from 157,886 to 158,167 bp with a similar structure and composition to those of the genus Prunus. However, there were still minor differences in the cp genome that were mainly caused by the contraction and expansion of the IR region, and six types of SSR in which mono-nucleotide repeats were the most dominant type of repeats in the cp genome. The genes rpl33 and psbI, and intergenic regions of start-psbA, rps3-rpl22, and ccsA-ndhD, showed the highest nucleotide polymorphism in the whole cp genome. A total of 325 SNPs were detected in the 146 cp genomes, and more than 70% of the SNPs were in region of large single-copy (LSC). The SNPs and haplotypes in the cp genome indicated that the wild group had higher genetic diversity than the domesticated and bred groups. In addition, among wild populations, Southwest China, including Yunnan, Tibet, and Bijie of Guizhou, had the highest genetic diversity. The genetic relationship of Japanese apricot germplasm resources in different regions showed a degree of correlation with their geographical distribution. Conclusion Comparative analysis of chloroplast genomes of 146 Japanese apricot resources was performed to analyze the used to explore the genetic relationship and genetic diversity among Japanese apricot resources with different geographical distributions, providing some reference for the origin and evolution of Japanese apricot.

In this paper, we investigated the unstable periodic orbits of a nonlinear chaotic generalized Lorenz-type system. By means of the variational method, appropriate symbolic dynamics are put forward, and the homotopy evolution approach, which can be used in the initialization of the cycle search, is introduced. Fourteen short unstable periodic orbits with different topological lengths, under specific parameter values, are calculated. We also explored the continuous deformation for part of the orbits while changing the parameter values, which provides a new approach to observe various bifurcations. The scale transformation of the generalized Lorenz-type system leads to a single parameter system known as the diffusionless Lorenz equations. By systematically calculating the periodic orbits in the diffusionless Lorenz equations, our research shows the efficiency of this topological classification method for the periodic solutions in the variants of a classical Lorenz system.

In this work, the characteristics of 2νββ decays for six nuclei ( Ar, Ca, Ca, Cr, Zn, and Xe) in a mass range from to are studied within the nuclear shell model (NSM) framework. Calculations are presented for the half-lives, nuclear matrix elements (NMEs), phase space factors ( ), and convergence of the NMEs. The theoretical results agree well with the experimental data. In addition, we predict the half-lives of decays for four nuclei. We focus on the convergence of the NMEs by analyzing the number of contributing intermediate states ( ) for the nuclei of interest. We assume that is safely determined when the accumulated NMEs saturate 99.7% of the final calculated magnitude. From the calculations of the involved nuclei, we discover a connection between and the total number of intermediate states ( ). According to the least squares fit, we conclude that the correlation is .