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The electronic, catalytic, and optical properties of transition metal dichalcogenides (TMDs) are significantly affected by oxidation, and using oxidation to tune the properties of TMDs has been actively explored. In particular, because transition metal oxides (TMOs) are promising hole injection layers, a TMD−TMO heterostructure can be potentially applied as a p-type semiconductor. However, the oxidation of TMDs has not been clearly elucidated because of the structural instability and the extremely small quantity of oxides formed. Here, we reveal the phases and morphologies of oxides formed on twodimensional molybdenum disulfide (MoS 2 ) using transmission electron microscopy analysis. We find that MoS 2 starts to oxidize around 400 °C to form orthorhombic-phase molybdenum trioxide (α-MoO 3 ) nanosheets. The α-MoO 3 nanosheets so formed are stacked layer-by-layer on the underlying MoS 2 via van der Waals interaction and the nanosheets are aligned epitaxially with six possible orientations. Furthermore, the band gap of MoS 2 is increased from 1.27 to 3.0 eV through oxidation. Our study can be extended to most TMDs to form TMO−TMD heterostructures, which are potentially interesting as p-type transistors, gas sensors, or photocatalysts.

Adipose tissue secretes many adipokines which contribute to various metabolic processes, such as blood pressure, glucose homeostasis, inflammation and angiogenesis. The biology of adipose tissue in an obese individual is abnormally altered in a manner that increases the body’s vulnerability to immune diseases, such as psoriasis. Psoriasis is considered a chronic inflammatory skin disease which is closely associated with being overweight and obese. Additionally, secretion of leptin, a type of adipokine, increases dependently on adipose cell size and adipose accumulation. Likewise, high leptin levels also aggravate obesity via development of leptin resistance, suggesting that leptin and obesity are closely related. Leptin induction in psoriatic patients is mainly driven by the interleukin (IL)-23/helper T (Th) 17 axis pathway. Furthermore, leptin can have an effect on various types of immune cells such as T cells and dendritic cells. Here, we discuss the relationship between obesity and leptin expression as well as the linkage between effect of leptin on immune cells and psoriasis progression.

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Two-dimensional (2D) materials have received much attention in view of their superior properties and their exotic behavior both of which result from their atomic scale thickness 1,2 .To further improve and modulate these properties, various methods including substitutional doping, functionalization, and defect engineering have been explored [3][4][5] . Among these, intercalation has numerous advantages in that new optical, magnetic, electronic or even