Publications by authors named "Chang'an Li"

We propose helical topological superconductivity away from the Fermi surface in three-dimensional time-reversal-symmetric odd-parity multiband superconductors. In these systems, pairing between electrons originating from different bands is responsible for the corresponding topological phase transition. Consequently, a pair of helical topological Dirac surface states emerges at finite excitation energies.

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The non-Hermitian skin effect is a unique phenomenon in which an extensive number of eigenstates are localized at the boundaries of a non-Hermitian system. Recent studies show that the non-Hermitian skin effect is significantly suppressed by magnetic fields. In contrast, we demonstrate that the second-order skin effect (SOSE) is robust and can even be enhanced by magnetic fields.

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Fluctuations in planar magnetotransport are ubiquitous in topological HgTe structures, in both tensile (topological insulator) and compressively strained layers (Weyl semimetal phase). We show that the common reason for the fluctuations is the presence of tilted Dirac cones combined with the formation of charge puddles. The origin of the tilted Dirac cones is the mix of the Zeeman term due to the in-plane magnetic field and quadratic contributions to the dispersion relation.

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The global spread of colistin or carbapenem-resistant Enterobacteriaceae (CRE) has been a pressing threat to public health. Members of Enterobacteriaceae, especially and have been prevalent foodborne pathogens and such pathogens from fresh vegetables have triggered foodborne illness in China. However, reports about CRE, especially from fresh vegetables, are still lacking.

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Crude electronic waste (e-waste) recycling has been banned due to the serious environmental pollution it caused, leaving many abandoned e-waste sites. However, information on the current levels and associated ecological risks of e-waste-derived contaminants such as polychlorinated biphenyls (PCBs) in e-waste site is limited. Wild fish, because they can accumulate high pollutant levels, are suitable indicators for environmental pollution monitoring and has been widely employed as biomonitoring.

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Article Synopsis
  • Tracheal stents can help relieve airway obstruction in patients with malignant tracheoesophageal fistula (MTEF) following immunotherapy, as demonstrated in a case study with a 58-year-old male.
  • The patient experienced airway obstruction due to advanced esophageal cancer, and after receiving stents and immunotherapy, his condition remained stable despite the fistula's progression.
  • The study suggests that using properly sized stents with immune therapies may enhance patient quality of life and potentially increase survival rates in those suffering from MTEF.
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We study the higher-order topological spin phases based on a spin analogue of Benalcazar-Bernevig-Hughes model in two dimensions using large-scale quantum Monte Carlo simulations. A continuous Néel-valence bond solid quantum phase transition is revealed by tuning the ratio between dimerized spin couplings, namely, the weak and strong exchange couplings. Through the finite-size scaling analysis, we identify the phase critical points, and consequently, map out the full phase diagrams in related parameter spaces.

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Magnetic oscillations of Dirac surface states of topological insulators are typically expected to be associated with the formation of Landau levels or the Aharonov-Bohm effect. We instead study the conductance of Dirac surface states subjected to an in-plane magnetic field in the presence of a barrier potential. Strikingly, we find that, in the case of large barrier potentials, the surface states exhibit pronounced oscillations in the conductance when varying the magnetic field, in the absence of Landau levels or the Aharonov-Bohm effect.

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Background: Since 2020 COVID-19 pandemic became an emergent public sanitary incident. The epidemiology data and the impact on prognosis of secondary infection in severe and critical COVID-19 patients in China remained largely unclear.

Methods: We retrospectively reviewed medical records of all adult patients with laboratory-confirmed COVID-19 who were admitted to ICUs from January 18th 2020 to April 26th 2020 at two hospitals in Wuhan, China and one hospital in Guangzhou, China.

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We propose an intrinsic three-dimensional Fabry-Pérot type interferometer, coined "higher-order interferometer," that is based on the chiral hinge states of second-order topological insulators and cannot be mapped to an equivalent two-dimensional setting because of higher-order topological obstructions. Quantum interference patterns in the two-terminal conductance of this interferometer are controllable not only by tuning the strength but also, particularly, by rotating the direction of the magnetic field applied perpendicularly to the transport direction. Remarkably, the conductance exhibits a characteristic beating pattern with multiple frequencies depending on the field strength and direction in a unique fashion.

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We investigate disorder-driven topological phase transitions in quantized electric quadrupole insulators in two dimensions. We show that chiral symmetry can protect the quantization of the quadrupole moment q_{xy}, such that the higher-order topological invariant is well defined even when disorder has broken all crystalline symmetries. Moreover, nonvanishing q_{xy} and consequent corner modes can be induced from a trivial insulating phase by disorder that preserves chiral symmetry.

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There is little question that the "electronic revolution" of the 20th century has impacted almost every aspect of human life. However, the emergence of solid-state electronics as a ubiquitous feature of an advanced modern society is posing new challenges such as the management of electronic waste (e-waste) that will remain through the 21st century. In addition to developing strategies to manage such e-waste, further challenges can be identified concerning the conservation and recycling of scarce elements, reducing the use of toxic materials and solvents in electronics processing, and lowering energy usage during fabrication methods.

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As the three-dimensional analogs of graphene, Weyl semimetals display signatures of chiral anomaly which arises from charge pumping between the lowest chiral Landau levels of the Weyl nodes in the presence of parallel electric and magnetic fields. In this work, we study the pseudo chiral anomaly and its transport signatures in graphene ribbon with zigzag edges. Here 'pseudo' refers to the case where the inverse of width of zigzag graphene ribbon plays the same role as magnetic field in three-dimensional Weyl semimetals.

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Rapid urbanization significantly changes vegetation coverage and heat distribution, which threatens the sustainable development and the quality of life. As the largest developing city in Central China, Wuhan was chosen as the experimental region. This study investigated the urbanization process of Wuhan from 1989 to 2917 based on Landsat data.

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A novel Eu-TiO₂ nanocomposite prepared by a sol-gel method is used for the degradation of rhodamine B (RhB) present in dyes wastewater. The X-ray diffraction (XRD), Raman spectroscopy and transmission electron microscopy (TEM) show the anatase phase and globular shape of Eu- TiO₂ nanocomposite, UV-vis diffuse reflectance spectroscopy and low temperature N₂ adsorption (BET) indicate Eu-TiO₂ possesses a narrow band gap (2.98 eV) and a high specific surface area (112.

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A linear trinuclear ferrous complex [FeII3(pymp)4(MeOH)2][BPh4]2·2MeOH (1) (Hpymp = 2-[(pyridine-2-ylimine)-methyl]phenol) was isolated and characterized both structurally and magnetically. A magnetic study revealed the ferromagnetic coupling (J = +3.54 cm-1) within the [FeII3] units and uniaxial magnetic anisotropy (D = -1.

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Objective: To characterize the class I integron in Acinetobacter baumannii and to analyze the correlation between integron and drug resistance.

Methods: In total 187 strains were collected between 2008 and 2009. All strains were tested by Kirb-Bauer disk diffusion test for drug resistance.

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