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Transition metal oxides (TMOs) have potential as active materials for information storage devices due to their diverse structural–chemical–physical properties. Among the many TMOs, tungsten oxide (WOx) is a promising candidate because the oxygen concentration can control the crystal structure. The 1D atomic defect tunnel structure of oxygen‐deficient WOx is a suitable platform to realize storage devices. Recently, the relationship between the crystal structure and the optical–electrical–thermal transport properties of WOx using high‐quality epitaxial films has been elucidated and an electrochemical redox device using WOx films with a 1D atomic defect tunnel structure has been demonstrated using this relationship. Herein, the 1D atomic defect tunnel structure of oxygen‐deficient WOx epitaxial films and its redox device applications are reviewed based on these efforts. [ABSTRACT FROM AUTHOR]

Since the optoelectronic properties of VO2 are modulated around the critical temperature (Tc) of insulator‐to‐metal transition, VO2 is a promising candidate material for smart window. However, the Tc of bulk VO2 is rather high 341 K (68 °C) and therefore, needs to be decreased down to near temperature for practical applications. Although Tc can be reduced to room temperature if rutile TiO2 crystal is used as the substrate, it is not technologically viable for large‐scale applications because of the size limitation of available TiO2 crystal. Here, this work shows that the Tc can be reduced to near room temperature using M‐plane sapphire as the substrate. VO2/TiO2 bilayer films are fabricated with varied thicknesses on M‐plane sapphire [(101¯0) α‐Al2O3] substrates. The 5.5‐nm‐thick VO2 film on 200‐nm‐thick TiO2 buffered sapphire substrate shows clear insulator‐to‐metal transition at ≈305 K (32 °C). It is also found that the insulator‐to‐metal transition is sensitive to the in‐plane lattice distortion, which induces carrier generation. The systematic study on the effect of in‐plane lattice distortion on the insulator‐to‐metal transition of VO2 will be useful for the practical application of VO2 as an active material of smart window. [ABSTRACT FROM AUTHOR]

Cas2 protein in the CRISPR‐Cas system functions as a scaffold for the acquisition of foreign DNA fragments, and as a nuclease against DNA and RNA substrates. Crystal structures of Cas2 have shown catalytically inactive conformational states that do not explain the mechanism of Cas2 nuclease activity. Here, we report that Xanthomonas albilineans Cas2 (XaCas2) assumes an inactive conformation in solution. Residual dipolar couplings and NMR relaxation, however, provide direct evidence on conformational dynamics at the predicted hinge region. Furthermore, XaCas2 transiently associates with metal ions for nuclease activity via highly mobile Asp8. Taken together, the dual function of Cas2 can be explained by a dynamic equilibrium of conformational states that serve as a scaffold or as a nuclease on demand. [ABSTRACT FROM AUTHOR]

The mannitol transporter enzyme IIMtl of the bacterial phosphotransferase system is a multi-domain protein that catalyzes mannitol uptake and phosphorylation. Here we investigated the domain association between cytosolic A and B domains of enzyme IIMtl, which are natively connected in Escherichia coli, but separated in Thermoanaerobacter tengcongensis. NMR backbone assignment and residual dipolar couplings indicated that backbone folds were well conserved between the homologous domains. The equilibrium binding of separately expressed domains, however, exhibited ∼28-fold higher affinity compared to the natively linked ones. Phosphorylation of the active site loop significantly contributed to the binding by reducing conformational dynamics at the binding interface, and a few key mutations at the interface were critical to further stabilize the complex by hydrogen bonding and hydrophobic interactions. The affinity increase implicated that domain associations in cell could be maintained at an optimal level regardless of the linker. [ABSTRACT FROM AUTHOR]

Exotic electron transport properties such as quasi 1D conductivity are useful to realize advanced electronic devices showing unique properties. Anisotropic electron transport properties are often found in complex metal oxides due to their complicated crystal structures. Although simple metal oxides with distorted crystal structures could also be expected to show anisotropic electron transport properties, it is rarely studied most likely due to the lack of their high‐quality epitaxial films. Here anisotropic electron transport properties, showing "fast electron transport path," in a simple distorted metal oxide, NbO2, is reported. High‐quality NbO2 epitaxial films with different crystallographic orientations on (0001) and (11¯02) α‐Al2O3 single crystal substrates are fabricated, and the electron transport properties at room temperature are measured. Both the resistivity and absolute value of the thermopower along the [112¯] NbO2 is pretty small as compared with other directions. Experimentally obtained electron carrier effective mass in the [112¯] direction is surprisingly small, only 0.051 me, which is similar to that of high‐mobility GaAs. Since simple metal oxides have several advantages against complex oxides in view of easy fabrication, the present results will be beneficial for realizing advanced electronic devices using simple metal oxides. Fast electron transport path of a simple metal oxide with distorted crystal structure is demonstrated by measuring the electron transport properties of the NbO2 epitaxial films grown on α‐Al2O3 substrates. Experimentally obtained electron carrier effective mass in the [112¯] direction is surprisingly small (0.051 me), demonstrating quasi 1D conductivity of NbO2. [ABSTRACT FROM AUTHOR]