8 research outputs found
Observation of Flat Band and Van Hove Singularity in Non-superconducting Nitrogen-doped Lutetium Hydride
Hydrogen-rich materials offer a compelling avenue towards room temperature
superconductivity, albeit under ultra-high pressure. However, the experimental
investigation of the electronic band structure remains elusive, due to the
inherent instability of most of the hydrogen-rich materials upon pressure
release. Very recently, nitrogen-doped lutetium hydride was claimed to host
room temperature superconductivity under near ambient pressure but was
disproven by following works. Upon decompression, nitrogen doped lutetium
hydride manifests a stable metallic phase with dark blue color. Moreover, high
temperature superconductivity has been reported in lutetium hydrides Lu4H23
(~71 K) under around 200 GPa. These properties engender an unprecedented
opportunity, allowing for the experimental investigation of the electronic band
structure intrinsic to hydrogen-rich material. In this work, using angle
resolved photoemission spectroscopy to investigate the non-superconducting
nitrogen doped lutetium hydride, we observed significant flat band and Van Hove
singularity marginally below the Fermi level. These salient features,
identified as critical elements, proffer potential amplifiers for the
realization of heightened superconductivity, as evidenced by prior research.
Our results not only unveil a confluence of potent strong correlation effects
and anisotropy within the Lu-H-N compound, but also provide a prospect for
engineering high temperature superconductivity through the strategic
manipulation of flat band and the VHS, effectively tailoring their alignment
with the Fermi energy.Comment: 26 pages, 9 figure
The aging lung: microenvironment, mechanisms, and diseases
With the development of global social economy and the deepening of the aging population, diseases related to aging have received increasing attention. The pathogenesis of many respiratory diseases remains unclear, and lung aging is an independent risk factor for respiratory diseases. The aging mechanism of the lung may be involved in the occurrence and development of respiratory diseases. Aging-induced immune, oxidative stress, inflammation, and telomere changes can directly induce and promote the occurrence and development of lung aging. Meanwhile, the occurrence of lung aging also further aggravates the immune stress and inflammatory response of respiratory diseases; the two mutually affect each other and promote the development of respiratory diseases. Explaining the mechanism and treatment direction of these respiratory diseases from the perspective of lung aging will be a new idea and research field. This review summarizes the changes in pulmonary microenvironment, metabolic mechanisms, and the progression of respiratory diseases associated with aging