| RESEARCH HIGHLIGHTS |


acid inhibits proper development of these cells into mature, functional fat cells. Visceral fat cells are compromised in their proper fat functions, though they can expand in size by gobbling up excessive lipids. The researchers went on to demonstrate that the high levels of retinoic acid were due to its upregulation by a developmental factor called WT1, and that blocking WT1 or retinoic acid signaling reversed the developmental defect in visceral fat stem cells.


“Our findings imply that the developmental


origin of visceral fat is different from that of subcutaneous fat, and that this difference results in retinoic-acid-mediated differences in fat cell quality,” says Sugii. Owing to the relationship between


retinoic acid and visceral obesity, Sugii says that his team needs to now look closely at whether excessive intake of vitamin A increases the risk of visceral obesity. He also suggests that their findings could lead to


new treatments to prevent visceral obesity and its associated complications, such as metabolic diseases. “A potential therapeutic approach that targets


the retinoic acid signaling pathway would be worth testing for counteracting visceral obesity in animal models,” says Sugii.


1. Takeda, K., Sriram, S., Chan, X. H. D., Ong, W. K., Yeo, C. R. et al. Retinoic acid mediates visceral- specific adipogenic defects of human adipose- derived stem cells. Diabetes 65, 1164–1178 (2016).


Materials science:


UNDERSTANDING HOW FLAT PHOSPHORUS GROWS


MODELING THE GROWTH OF TINY FLAKES OF A TWO-DIMENSIONAL FORM OF PHOSPHORUS COULD HELP RESEARCHERS ONE DAY PRODUCE BETTER ELECTRONICS


The door to developing superior electronic devices, such as flexible circuits, has been nudged open by A*STAR researchers’ modeling of possible methods to manufacture one of the crucial ingredients. Phosphorene is a two-dimensional (2D)


form of the element phosphorus. Despite having electronic properties superior to other 2D materials such as graphene (2D carbon) and silicene (2D silicon), phosphorene’s potential for application in high-performance devices has been limited by how difficult it is to reliably produce commercially viable quantities of it in large, thin, high-quality nanosheet form. At present, phosphorene can only be obtained


by mechanical and chemical exfoliation of black phosphorus, which is costly and produces low yields of uneven films. Other 2D materials such as graphene and molybdenum disulfide can be directly grown using chemical vapor deposition


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and physical vapor deposition, but no such methods exist for growing phosphorene. The new model developed by Junfeng Gao


and colleagues from the A*STAR Institute of High Performance Computing will make it possible for researchers to tackle this challenging technical problem by choosing the best process conditions for the growth of large-size, high- quality phosphorene directly on a surface1. Gao and the team tried to find the best way


to grow high-quality single layers of phophorene directly on a surface by modeling the effect of different substrates on the growth of a phos- phorene flake containing just 27 atoms. “The stability of the growing nanof lake is


highly sensitive to the substrate and crucial to its continued growth,” explains Gao. “If the interaction strength is too weak, the substrate causes the flake to buckle; but if the interaction is too strong, the inner bonds


Black phosphorene (depicted above) nanoflakes are only dynamically stable on a moderate interaction substrate, leading to continuous growth of single layer phosphorene.


A*STAR RESEARCH 39


Reprinted with permission from Ref 1. Copyright (2016) American Chemical Society.


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