Tunable Dirac Fermion Dynamics in Topological Insulators

Three-dimensional topological insulators are characterized by insulating bulk state and metallic surface state involving Dirac fermions that behave as massless relativistic particles. These Dirac fermions are responsible for achieving a number of novel and exotic quantum phenomena in the topological insulators and for their potential applications in spintronics and quantum computations. It is thus essential to understand the electron dynamics of the Dirac fermions, i.e., how they interact with other electrons, phonons and disorders. Here we report super-high resolution angle-resolved photoemission studies on the Dirac fermion dynamics in the prototypical Bi2(Te,Se)3 topological insulators. We have directly revealed signatures of the electron-phonon coupling in these topological insulators and found that the electron-disorder interaction is the dominant factor in the scattering process. The Dirac fermion dynamics in Bi2(Te3-xSex) topological insulators can be tuned by varying the composition, x, or by controlling the charge carriers. Our findings provide crucial information in understanding the electron dynamics of the Dirac fermions in topological insulators and in engineering their surface state for fundamental studies and potential applications.Comment: 14 Pages, 4 Figure

Functional and structural analysis of a novel splice site HMBS variant in a Chinese AIP patient

Background: Acute intermittent porphyria (AIP) is a rare metabolic disorder that results from mutations in the gene encoding hydroxymethylbilane synthase (HMBS), an enzyme involved in heme biosynthesis. AIP follows an autosomal dominant inheritance pattern, but most carriers are asymptomatic. The clinical manifestations of AIP include acute attacks of abdominal pain and neuropsychiatric disturbances. The pathogenicity of novel HMBS variants identified in Chinese patients has not been well established.Objective: The article aims to identify the pathogenic mutation in an AIP patient and prove its pathogenicity through in vitro experiments.Methods: A 22-year-old female diagnosed with AIP participated in the study. Variant screening of her HMBS gene was carried out through Sanger sequencing. To ascertain the consequences of the newly discovered variant, we conducted in vitro experimentation targeting HMBS gene expression and enzymatic function. Additionally, protein structure analysis was performed. Cycloheximide treatment and UPF1-specific siRNA knockdown were employed to assess the impact of the mutation on the mechanism of non-sense-mediated mRNA decay (NMD).Results: A novel splice site variant in the HMBS gene (c.648_651+1delCCAGG) was detected in the patient, which caused aberrant mRNA splicing. In vitro experiments demonstrated that this variant significantly decreased the expression of HMBS. Further investigation confirmed that this decrease was due to NMD. Additionally, structural analysis indicated that this variant would destabilize the HMBS protein and impair its catalytic activity. To gain a comprehensive understanding of HMBS mutations in the context of AIP, we conducted a literature search on PubMed using the keywords ‘HMBS’ and ‘Acute intermittent porphyria’ from 2013 to 2023. This search yielded 19 clinical case reports written in English, which collectively described 220 HMBS gene mutations worldwide.Conclusion: The study identified and proved the pathogenicity of a novel splice site HMBS variant for the first time. Our results elucidated the pathological mechanism by which this mutation causes AIP through reducing HMBS expression and activity. These findings provide theoretical guidance for the diagnosis, treatment and genetic counseling of AIP patients

Anomalous High-Energy Waterfall-Like Electronic Structure in 5 \u3cem\u3ed\u3c/em\u3e Transition Metal Oxide Sr\u3csub\u3e2\u3c/sub\u3eIrO\u3csub\u3e4\u3c/sub\u3e with a Strong Spin-Orbit Coupling

The low energy electronic structure of Sr2IrO4 has been well studied and understood in terms of an effective Jeff = 1/2 Mott insulator model. However, little work has been done in studying its high energy electronic behaviors. Here we report a new observation of the anomalous high energy electronic structure in Sr2IrO4. By taking high-resolution angle-resolved photoemission measurements on Sr2IrO4 over a wide energy range, we have revealed for the first time that the high energy electronic structures show unusual nearly-vertical bands that extend over a large energy range. Such anomalous high energy behaviors resemble the high energy waterfall features observed in the cuprate superconductors. While strong electron correlation plays an important role in producing high energy waterfall features in the cuprate superconductors, the revelation of the high energy anomalies in Sr2IrO4, which exhibits strong spin-orbit coupling and a moderate electron correlation, points to an unknown and novel route in generating exotic electronic excitations

Cholesterol-Lowering Effect of Allicin on Hypercholesterolemic ICR Mice

Allicin was discussed as an active compound with regard to the beneficial effects of garlic in atherosclerosis. The aim of this study was to investigate the cholesterol-lowering properties of allicin. In order to examine its effects on hypercholesterolemia in male ICR mice, this compound with doses of 5, 10, or 20 mg/kg body weight was given orally daily for 12 weeks. Changes in body weight and daily food intake were measured regularly during the experimental period. Final contents of serum cholesterol, triglyceride, glucose, and hepatic cholesterol storage were determined. Following a 12-week experimental period, the body weights of allicin-fed mice were less than those of control mice on a high-cholesterol diet by 38.24±7.94% (P<0.0001) with 5 mg/kg allicin, 39.28±5.03% (P<0.0001) with 10 mg/kg allicin, and 41.18±5.00% (P<0.0001) with 20 mg/kg allicin, respectively. A decrease in daily food consumption was also noted in most of the treated animals. Meanwhile, allicin showed a favorable effect in reducing blood cholesterol, triglycerides, and glucose levels and caused a significant decrease in lowering the hepatic cholesterol storage. Accordingly, both in vivo and in vitro results demonstrated a potential value of allicin as a pronounced cholesterol-lowering candidate, providing protection against the onset of atherosclerosis

A path to human‐raccoon dog harmony: Identifying factors influencing the tolerance of urban residents in Shanghai towards a neglected species

Abstract Human‐wildlife interactions become increasingly common in urban areas across all continents and ecosystem types. Depending on the context, human‐wildlife interactions can be categorized as harmonious, neutrality, or in conflict and raises cultural, economic and ecological challenges in maintaining urban biodiversity. Understanding the mechanism behind the tolerance of residents to the presence of wildlife is vital to promoting a harmonious coexistence between humans and wildlife in urban environments. To advance our knowledge of this mechanism, we developed a questionnaire to survey residents in Shanghai, China about their knowledge of and attitude towards raccoon dogs (Nyctereutes procyonoides), a species whose population is increasing in urban areas. Using 281 questionnaires, we conducted structural equation modelling to examine how relational values, including familiarity with raccoon dogs, perceived benefits and risks, together with residents' trust in wildlife management authorities, interactively influence the tolerance for this species. We found that the residents' familiarity with raccoon dogs positively influenced their tolerance, both directly and indirectly through increased perceived benefits and reduced perceived risks. Furthermore, trust in wildlife management authorities contributed to higher tolerance through perceived benefits. Our results suggested that education about the relational values of raccoon dogs to the public can reduce the traditional negative connotation for this species and promote the coexistence of people and raccoon dogs in Shanghai urban environment. Based on our understanding about how raccoon dogs were culturally constructed and the willingness of residents to share landscapes with the species, we advocate that relational values play an important role in future urban biodiversity conservation planning. We also advocate for education programs that familiarize the public with raccoon dogs as well as other species, which can turn urban human‐wildlife conflicts into harmonious relationships in Shanghai and other urban areas. Read the free Plain Language Summary for this article on the Journal blog