The intestinal microbiota affect various physiological traits of host animals such as brain development, obesity, age, and the immune system. In the swine industry, understanding the relationship between intestinal microbiota and growth stage is essential because growth stage is directly related to the feeding system of pigs, thus we studied the intestinal microbiota of 32 healthy pigs across five sows at 10, 21, 63, 93, and 147 d of ages. The intestinal microbiota were altered with growth of pigs and were separated into three distinct clusters. The relative abundance of several phyla and genera were significantly different between growth stages. We observed co-occurrence pattern of the intestinal microbiota at each growth stage. In addition, we predicted the functions of the intestinal microbiota and confirmed that several KEGG pathways were significantly different between growth stages. We also explored the relationship between the intestinal microbiota and innate factors such as the maternal effect and gender. When pigs were young, innate factors affected on construction of intestinal microbiota, however this tendency was disappeared with growth. Our findings broaden the understanding of microbial ecology, and the results will be used as a reference for investigating host-microbe interactions in the swine industry.

Layered transition metal dichalcogenides MoTe2 and WTe2 share almost similar lattice constants as well as topological electronic properties except their structural phase transitions. While the former shows a first-order phase transition between monoclinic and orthorhombic structures, the latter does not. Using a recently proposed van der Waals density functional method, we investigate structural stability of the two materials and uncover that the disparate phase transitions originate from delicate differences between their interlayer bonding states near the Fermi energy. By exploiting the relation between the structural phase transitions and the low energy electronic properties, we show that a charge doping can control the transition substantially, thereby suggesting a way to stabilize or to eliminate their topological electronic energy bands. Because of the layered structures of TMDs, several polymorphs can exist and show characteristic physical properties depending on their structures 8 . A typical TMD shows the trigonal prismatic (2H) or the octahedral (1T ) structures 9-12 . For MoTe 2 and WTe 2 , the 2H structure (α-phase, P 6 3 /mmc) is a stable semiconductor while the 1T form is unstable 7,13 . The unstable 1T structure turns into the distorted octahedral one (1T ′ ) 7,14 . The stacked 1T ′ single layer forms a threedimensional bulk with the monoclinic structure (β-phase, P 2 1 /m) or the orthorhombic one (γ-phase, P mn2 1 ) (see Fig. 1) [15][16][17] . Interestingly, the β phase with a few layers is a potential candidate of QSH insulator 7 and the bulk γ phase shows type-II Weyl semimetalic energy bands 4,18,19 , respectively. Since the structural differences between β and γ phases are minute (∼4• tilting of axis along out-of-plane direction in β phase with respect to one in γ phase), the sensitive change in their topological low energy electronic properties is remarkable and the transition between different structures can lead to alternation of topological properties of the system.A phase transition between the β-and γ-phase in the layered TMDs has been known for a long time 16,20 . MoTe 2 shows a first-order transition from the β-to γ-structure at around 250 K 20 when temperature decreases. WTe 2 , however, does not show any transition and stays at the γ-phase 21,22 . Since the structural parameters of a single layer of 1T ′ -MoTe 2 and 1T ′ -WTe 2 are almost the same 15,17,23 and Mo and W belong to the same group in the periodic table, the different phase transition behaviors are intriguing and origins of the contrasting features are yet to be clarified. To understand the phase transition, the proper treatment of long and short range interlayer interaction in TMDs is essential. Most of the theoretical studies, however, fail to reproduce the experimental crystal structures of the two phases of MoTe 2 and WTe 2 so do their topological electronic structures using crystal structures obtained from ab initio calculations [24][25][26][27][28][29][30] . Instead, the atomic structures from experiment data are r...

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