Weyl fermions, Fermi arcs, and minority-spin carriers in ferromagnetic CoS ₂

Abstract

Magnetic Weyl semimetals are a newly discovered class of topological materials that may serve as a platform for exotic phenomena, such as axion insulators or the quantum anomalous Hall effect. Here, we use angle-resolved photoelectron spectroscopy and ab initio calculations to discover Weyl cones in CoS2, a ferromagnet with pyrite structure that has been long studied as a candidate for half-metallicity, which makes it an attractive material for spintronic devices. We directly observe the topological Fermi arc surface states that link the Weyl nodes, which will influence the performance of CoS2 as a spin injector by modifying its spin polarization at interfaces. In addition, we directly observe a minority-spin bulk electron pocket in the corner of the Brillouin zone, which proves that CoS2 cannot be a true half-metal.

Emerging roles of non-histone protein crotonylation in biomedicine

“…1 ). Yu et al [ 52 ] reported that CDYL can negatively regulate the Kcr of RPA1 on multiple lysine sites, which is a reaction to DNA-damaging insults.…”

“…Crotonylation of some protein sites cannot be detected in wild types cells. In order to find out which lysine sites may be crotonylated, some studies use drugs that promote crotonylation or knock down the expression of “modulators” of crotonylation during cell culture, such as sodium crotonate (NACR) which promotes non-histone crotonylation by conversion to crotonyl-coenzyme A [ 49 ], and HDAC inhibitor SAHA [ 21 ] or crotonyl-CoA hydrolase CDYL [ 52 ] which negatively regulate Kcr. But more researchers collect biological samples under interested conditions for modification (Table 3 ).…”

“…Its advantage is the high efficiency for protein labeling, while its disadvantage is time consuming. Metabolic labeling has been successfully used to reveal the relative changes of crotonylation of non-histone proteins in homologous recombination-mediated DNA repair [ 52 ].…”

“…To reduce the complexity of samples, after digestion, the trypsin polypeptides can be divided into several components by high-pH reversed-phase fractionation (RPF), known as sample fractionation. To increase the depth of the crotonylation analysis, immunoaffinity purification is usually used, in which the pan-Kcr antibody is immobilized to a resin bead and selectively bound to the crotonylated tryptic peptides and is then eluted [ 17 , 52 , 60 , 61 ]. Enrichment of crotonylated peptides is usually combined with sample fractionation to improve the efficiency of the next mass spectrometry (MS).…”

“…Crotonylation was initially found to occur mainly in histones. However, a significant conclusion from recent proteomic studies is that most crotonylation events occur on non-histone proteins [ 17 , 52 , 56 , 61 , 68 ]. MS-based proteomics methods are now used in a variety of organisms not limited to humans, resulting in the identification of thousands of new crotonylation sites (Table 3 ).…”