Phase-Modulated Elastic Properties of 2D Magnetic FeTe: Hexagonal and Tetragonal Polymorphs.

2D layered magnets, such as iron chalcogenides, have emerged these years as a new family of unconventional superconductors and provided the key insights to understand the phonon-electron interaction and pairing mechanism. Their mechanical properties are of strategic importance for the potential applications in spintronics and optoelectronics. However, there is still a lack of efficient approach to tune the elastic modulus despite the extensive studies. Herein, the modulated elastic modulus of 2D magnetic FeTe and its thickness-dependence is reported via phase engineering. The grown 2D FeTe by chemical vapor deposition can present various polymorphs, that is tetragonal FeTe (t-FeTe, antiferromagnetic) and hexagonal FeTe (h-FeTe, ferromagnetic). The measured Young's modulus of t-FeTe by nanoindentation method shows an obvious thickness-dependence, from 290.9 ± 9.2 to 113.0 ± 8.7 GPa when the thicknesses increased from 13.2 to 42.5 nm, respectively. In comparison, the elastic modulus of h-FeTe remains unchanged. These results can shed light on the efficient modulation of mechanical properties of 2D magnetic materials and pave the avenues for their practical applications in nanodevices.

Effect of Dahuang Danpi Decoction on Lactobacillus bulgaricus growth and metabolism: In vitro study.

Gut flora plays an essential role in disease and health. A traditional Chinese herb formula, Dahuang Danpi Decoction (DDD) can alleviate several gastrointestinal diseases.In the present study, we assessed the effect of DDD on the growth and metabolism of Lactobacillus bulgaricus. L bulgaricus was cultured in MRS with 40 mg/ml (high), 10 mg/ml (medium), and 2.5 mg/ml (low) of DDD, Ceftriaxone and blank (control). The growth of L bulgaricus was measured by optical density. The levels of L-lactic acid and D-lactic acid were also measured.Compared to the control group, the concentrations of L bulgaricus in the medium and the high concentrations DDD groups were significantly higher (P < .001 for all), while the concentrations of L bulgaricus in the ceftriaxone groups were significantly lower. In the 3 DDD groups, the L- lactic acid levels were significantly higher than those in the control group and the ceftriaxone groups (P < .001 for all), and the L-lactic acid level was the highest in the high DDD group. Similarly, the D-lactic acid level in the high concentration DDD group was significantly higher than those in the medium and low concentration DDD groups, the control group and the ceftriaxone groups. Both the L-lactic acid and D-lactic acid levels were lower than those in the control group and the DDD groups.DDD could dose-dependently promote the growth of L bulgaricus and enhance the secretion of L-lactic acid and D-lactic acid, which suggests DDD may be able to interact with the probiotics, improve the gut microbiota, and serve in the prevention and treatment of dysbiosis.