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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. PACS numbers: 73.22.-f, 71.15.Mb, 64.70.Nd Since the successful exfoliation of various two dimensional (2D) crystals in 2005 1 , the layered materials in a single layer as well as bulk forms have attracted serious attention owing to their versatile physical properties 2,3. Among them, the layered transition metal dichalco-genides (TMDs) show various interesting electronic properties such as type-II Weyl semimetallic (WSM) energy bands 4 , gate dependent collective phenomena 5,6 , and quantum spin Hall (QSH) insulating state 7 to name a few. 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 octa-hedral (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 three-dimensional bulk with the monoclinic structure (β-phase, P 2 1 /m) or the orthorhombic one (γ-phase, P mn2 1) (see Fig. 1) 15-17. 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 ...

DNA methylation is an essential epigenetic modification in the human genome. For the investigation of DNA methylation patterns, bisulfite conversion and DNA sequencing is a method of choice, because it provides detailed information on the methylation pattern of individual DNA molecules at single CG site resolution. The method is based on the deamination of cytosine residues to uracils in the presence of NaOH and sodium bisulfite. Since methylcytosine is not converted under these conditions, the original methylation state of the DNA can be analyzed by sequencing of the converted DNA. After the conversion reaction, the DNA sequence under investigation is amplified by polymerase chain reaction (PCR) with primers specific for one strand of the bisulfite-converted DNA. The PCR product is cloned and individual clones are sequenced. Here, we describe an advanced protocol for bisulfite conversion, protocols for cloning, and tools for primer design (Methprimer, Bisearch). In addition, we present tools for the web display of primary data and data analysis (BiQ Analyzer, BDPC) and describe the setup of a sequencing and analysis pipeline for medium to high throughput.

We present a detailed description of a classification scheme for phase transitions in finite systems based on the distribution of Fisher zeros of the canonical partition function in the complex temperature plane. We apply this scheme to finite Bose-systems in power law traps within a semi-analytic approach with a continuous one-particle density of states Ω(E) ∼ E d−1 for different values of d and to a three dimensional harmonically confined ideal Bose-gas with discrete energy levels. Our results indicate that the order of the Bose-Einstein condensation phase transition sensitively depends on the confining potential.