Phonon promoted charge density wave in topological kagome metal ScV6Sn6.

Charge density wave (CDW) orders in vanadium-based kagome metals have recently received tremendous attention, yet their origin remains a topic of debate. The discovery of ScV6Sn6, a bilayer kagome metal featuring an intriguing [Formula: see text] CDW order, offers a novel platform to explore the underlying mechanism behind the unconventional CDW. Here, we combine high-resolution angle-resolved photoemission spectroscopy, Raman scattering and density functional theory to investigate the electronic structure and phonon modes of ScV6Sn6. We identify topologically nontrivial surface states and multiple van Hove singularities (VHSs) in the vicinity of the Fermi level, with one VHS aligning with the in-plane component of the CDW vector near the [Formula: see text] point. Additionally, Raman measurements indicate a strong electron-phonon coupling, as evidenced by a two-phonon mode and new emergent modes. Our findings highlight the fundamental role of lattice degrees of freedom in promoting the CDW in ScV6Sn6.

Spectroscopic signature of obstructed surface states in SrIn2P2.

The century-long development of surface sciences has witnessed the discoveries of a variety of quantum states. In the recently proposed "obstructed atomic insulators", symmetric charges are pinned at virtual sites where no real atoms reside. The cleavage through these sites could lead to a set of obstructed surface states with partial electronic occupation. Here, utilizing scanning tunneling microscopy, angle-resolved photoemission spectroscopy and first-principles calculations, we observe spectroscopic signature of obstructed surface states in SrIn2P2. We find that a pair of surface states that are originated from the pristine obstructed surface states split in energy by a unique surface reconstruction. The upper branch is marked with a striking differential conductance peak followed by negative differential conductance, signaling its localized nature, while the lower branch is found to be highly dispersive. This pair of surface states is in consistency with our calculational results. Our finding not only demonstrates a surface quantum state induced by a new type of bulk-boundary correspondence, but also provides a platform for exploring efficient catalysts and related surface engineering.

Allium vegetable intake associated with the risk of incident gastric cancer: a continuous follow-up study of a randomized intervention trial.

BACKGROUND: Allium vegetable components have antibacterial, antioxidative, and immune modulation properties, thus potentially exhibiting antitumor effects. Despite evidence from case-control studies, prospective studies linking allium vegetables with gastric cancer (GC) have been sparse. OBJECTIVE: In a prospective study, we examined whether allium vegetable intake would change the risk of GC occurrence and whether the associations would be modified by vitamin supplementation, garlic supplementation, and Helicobacter pylori (H. pylori) treatment. METHODS: The study was conducted on the basis of the Shandong Intervention Trial, a randomized, placebo-controlled, factorial-designed trial (1995-2003) in a well-recognized high-risk area for GC in China. Participants were continuously followed up to December 2017 for 22.3 y (1995-2017). A total of 3229 subjects were included, with information on the intake of allium vegetables (garlic vegetables and scallions), collected by structured questionnaires in 1994. The associations of total and individual allium vegetable intake with the risk of GC were examined, respectively. RESULTS: During the follow-up, 144 incident cases of GC were identified. Garlic vegetable intake was associated with a decreased risk of incident GC (P-trend = 0.02; OR: 0.83; 95% CI: 0.70, 0.98, per 1 kg/y increment), whereas scallion intake showed no association (P-trend = 0.80). An inverse association of the risk of GC with total allium vegetable and garlic vegetable intake was particularly stronger among those receiving the placebo for vitamin supplementation or garlic supplementation, indicating potential effect modifications by nutritional supplementation on allium vegetable intake and the risk of developing GC. Similar findings were found for analyses of the combined prevalence of dysplasia or GC. CONCLUSIONS: We found a significant reduction in the risk of developing GC with increasing dietary intake of allium vegetables, particularly garlic vegetables. The findings add to the literature on the potential inverse association of garlic vegetable intake with the risk of GC, therefore holding public health implications for dietary recommendations. This trial was registered at clinicaltrials.gov as NCT00339768.