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We have performed an angle-resolved photoemission spectroscopy study of the BiS2-based superconductor Nd(O,F)BiS2. Two small electronlike Fermi surfaces around X(π,0) are observed, which enclose 2.4% and 1.1% of the Brillouin zone area, respectively, corresponding to an electron doping of 7% per Bi site. The Fermi surface topology is far from the nesting scenario proposed in most of the theoretical models for the BiS2-based superconductors. The conduction bands show significant anisotropic splitting along XM and Γ X, which is attributed to the cooperative effects of large spin-orbit coupling and interlayer coupling. The low-energy spectrum exhibits a weakly dispersing broad hump near the bottom of the conduction bands. This hump is drastically suppressed with increasing temperature, while the spectral weight at the Fermi level is essentially unaffected. These anomalous spectral features indicate that the electrons could be strongly coupled with the lattice in the low-temperature normal state of this superconductor. [ABSTRACT FROM AUTHOR]

We performed an angle-resolved photoemission spectroscopy study of the Ni-based superconductor SrNi2As2. Electron and hole Fermi surface pockets are observed, but their different shapes and sizes lead to very poor nesting conditions. The experimental electronic band structure of SrNi2As2 is in good agreement with first-principles calculations after a slight renormalization (by a factor 1.1), confirming the picture of Hund's exchange-dominated electronic correlations decreasing with increasing filling of the 3d shell in the Fe-, Co-, and Ni-based compounds. These findings emphasize the importance of Hund's coupling and 3d-orbital filling as key tuning parameters of electronic correlations in transition-metal pnictides. [ABSTRACT FROM AUTHOR]

We demonstrate, using first-principles calculations, that the electronic structure of FeSe1-xTex (x = 0.5) is topologically nontrivial and characterized by an odd Z2 invariant and Dirac cone type surface states, in sharp contrast to the end member FeSe (x = 0). This topological state is induced by the enhanced three-dimensionality and spin-orbit coupling due to Te substitution (compared to FeSe), and characterized by a band inversion at the Z point of the Brillouin zone, which is confirmed by our ARPES measurements. The results suggest that the surface of FeSe0.5Te0.5 may support a nontrivial superconducting channel in proximity to the bulk. [ABSTRACT FROM AUTHOR]

The electronic structure of the iron-based superconductor Ba2Ti2Fe2As4O (Tonsetc = 23.5 K) has been investigated by using angle-resolved photoemission spectroscopy and combined local density approximation and dynamical mean field theory calculations. The electronic states near the Fermi level are dominated by both the Fe 3d and Ti 3d orbitals, indicating that the spacer layers separating different FeAs layers are also metallic. By counting the enclosed volumes of the Fermi surface sheets, we observe a large self-doping effect; i.e., 0.25 electrons per unit cell are transferred from the FeAs layer to the Ti2As2O layer, leaving the FeAs layer in a hole-doped state. This exotic behavior is successfully reproduced by our dynamical mean field calculations, in which the self-doping effect is attributed to the electronic correlations in the 3d shells. Our work provides an alternative route of effective doping without element substitution for iron-based superconductors. [ABSTRACT FROM AUTHOR]

Objective: To summarize the clinical features and genetic characteristics of Zellweger spectrum disorder caused by PEX6 gene variation. Methods: This was a case series research. Clinical date and genetic results of 2 neonatal cases of Zellweger syndrome caused by PEX6 gene variation in Wuhan Children's Hospital, Tongji Medical College, Huazhong University of Science & Technology and Affiliated Hospital of Guangdong Medical University from July 2021 to July 2022 were retrospectively collected and analyzed. Literature up to August 2023 was searched from electronic databases of China National Knowledge Infrastructure (CNKI), Wanfang Data and PubMed with the combined keywords of "Zellweger syndrome" "Zellweger spectrum disorder", and "PEX6 gene" both in Chinese and English. The main clinical features and genetic characteristics of Zellweger spectrum disorder caused by PEX6 gene variation were summarized. Results: The 2 male neonates both developed clinical manifestations as dyspnea, hypotonia, feeding difficulties, enlarged fontanelle, and high palatine arch after birth. Biochemical parameters indicated elevated bile acids, and the cranial ultrasound showed the enlarged bilateral ventricles and subependymal cyst in both 2 neonates. Zellweger syndrome was confirmed by whole exome sequencing, and the results revealed PEX6 gene variation in the 2 neonates, including compound heterozygous variants c.315G>A and c.2095-3T>G, and homozygous variant c.506_507del. Case 1 was hospitalized for 5 days, and case 2 for 32 days; they both died shortly after being discharged (the specific time is unknown). Literature review found 26 patients, including 2 neonates in this study, with Zellweger spectrum disorder caused by PEX6 gene defect reported in 1 Chinese article and 11 English articles. Clinical features included hearing loss (19 cases), developmental delay (19 cases), vision impairment (19 cases), elevated very long chain fatty acids (17 cases), brain malformations (15 cases), hypotonia (12 cases), hepatic insufficiency (12 cases), distinctive facies (10 cases), and dental impairment (9 cases). Compound heterozygous variations dominated the variation types (15 cases), and the frameshift variations (16 cases) were the main pathogenic variations. Conclusions: Zellweger spectrum disorder should be considered when neonates show hypotonia, feeding difficulty, distinctive facial appearance, brain malformations and failure of hearing screening, or when older children show retinitis pigmentosa, sensorineural hearing loss, amelogenesis imperfecta and developmental delays. Detection of genetic variation in the PEX gene is crucial for definitive diagnosis.

Objective: To investigate the application of pulmonary ultrasound in the diagnosis of neonatal COVID-19. Methods: In this retrospective study, the clinical data of 5 infants, who were admitted to the Department of Neonatology in Wuhan Children's Hospital from 31(st) January to 25(th) February 2020, were collected. Bedsides pulmondary ultrasound was conducted on admission, during the hospitalization, and before discharge, the result were compared with the chest X-ray or CT done at the same time. Results: Among the 5 cases who aged 1-18 days, 3 were male. The main clinical manifestations were respiratory and gastrointestinal symptoms. The pulmonary ultrasonography on admission showed abnormal pleural line and pulmonary edema of different severity in all 5 cases, presented as increase and fusion of B-line, and pulmonary interstitial syndrome; among them, one case also had a small-range consolidation. The chest CT on admission showed no obvious parenchymal infiltration in 2 cases, small strip or patchy high-density shadow in 2 cases, and ground glass change in one case. The re-examination of ultrosound during the hospitalization and at discharge showed improvement in all cases and were consistent with the chest X-ray taken at the same time. Conclusions: The main changes on the pulmonary ultrasonography in neonates with COVID-19 pneumonia are increase and fusion of B-line, abnormal pleural line, and alveolar interstitial syndrome, and may coexist with small range of pulmonary consolidation. The sensitivity of pulmonary ultrasound is higher than that of chest X-ray and CT in the diagnosis of pulmonary edema, and could be used in monitoring and evaluation of the disease.