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We measure the electrical resistivity of hcp iron up to ∼170  GPa and ∼3000  K using a four-probe van der Pauw method coupled with homogeneous flattop laser heating in a DAC, and compute its electrical and thermal conductivity by first-principles molecular dynamics including electron-phonon and electron-electron scattering. We find that the measured resistivity of hcp iron increases almost linearly with temperature, and is consistent with our computations. The results constrain the resistivity and thermal conductivity of hcp iron to ∼80±5  μΩ cm and ∼100±10  W m^{-1} K^{-1}, respectively, at conditions near the core-mantle boundary. Our results indicate an adiabatic heat flow of ∼10±1  TW out of the core, supporting a present-day geodynamo driven by thermal and compositional convection.

ObjectiveTo investigate the resistance level of adult Aedes albopictus to commonly used insecticides in urban areas of Huzhou City， and analyze the trend of insecticide resistance.MethodsAedes albopictus larvae were collected from different urban areas of Huzhou City in 2019 and 2020. The larvae were reared to adults for determining resistance using the WHO standard test kits by contact tube method.ResultsThe mortality was 97.06%‒100.00% in adult Aedes albopictus mosquitoes exposed to 0.4% beta-cypermethrin， 0.1% deltamethrin， 0.5% malathion， 0.05% propoxur and 3% permethrin in 2019. While the adult mosquitoes exposed to 0.4% beta Cypermethrin， 0.08% beta Cypermethrin， 0.03% deltamethrin， 0.4% permethrin， 0.5% malathion and 0.02% propoxur in 2020， the adjusted mortality were 98.58%， 89.09%， 85.64%， 91.34%， 91.43% and 100% respectively . When the insecticide doses on medicated paper were high， the Huzhou populations of Aedes albopictus were sensitive to beta-cypermethrin， deltamethrin， malathion and propoxur， and showed suspected resistance to permethrin. While the Aedes albopictus were exposed to low testing dose， they showed suspected resistance to beta-cypermethrin， deltamethrin， permethrin and malathion， but remained to be sensitive to propoxur.ConclusionThe adult Aedes albopictus in Huzhou City from 2019 to 2020 was still sensitive to propoxur， but their resistance to malathion changes from sensitive to resistant. When the contact tube method is used for insecticide resistance， it is suggested that the accurate diagnostic dose should be obtained first before conducting further insecticide resistance tests.

Purpose: The resurgence of pertussis has occurred around the world. However, the epidemiological profiles of pertussis cannot be well understood by current diseases surveillance. This study was designed to understand the seroepidemiological characteristics of pertussis infection in the general population of Huzhou City, evaluate the prevalence infection of pertussis in the population, and offer insights to inform adjustments in pertussis prevention and control strategies. Methods: From September to October 2023, a cross-sectional serosurvey was conducted in Huzhou City, involving 1015 permanent residents. Serum samples were collected from the study subjects, and pertussis toxin IgG antibodies (Anti-PT-IgG) were quantitatively measured using enzyme-linked immunosorbent assay (ELISA). The analysis included the geometric mean concentration (GMC) of Anti-PT-IgG, rates of GMC≥40IU/mL, ≥100IU/mL, and <5IU/mL. Stratified comparisons were made based on age, vaccination history, and human categories. Results: Among the 1015 surveyed individuals, the geometric mean concentration (GMC) of Anti-PT-IgG was 10.52 (95% CI: 9.96–11.11) IU/mL, with a recent infection rate of 1.58%, a serum positivity rate of 11.43%, and a proportion with <5IU/mL of 40.49%. Among 357 children with clear vaccination history, susceptibility decreased with an increasing number of vaccine doses (Z = -6.793, P < 0.001). The concentration of Anti-PT-IgG exhibited a significant post-vaccination decline over time (Z = -5.143, P < 0.001). In women of childbearing age, the GMC of Anti-PT-IgG was 7.71 (95% CI: 6.90–8.62) IU/mL, with no significant difference in susceptibility among different age groups (χ2 = 0.545, P = 0.909). The annual pertussis infection rate in individuals aged ≥3 years was 9321 (95%CI: 3336–16039) per 100,000, with peak infection rates in the 20–29, 40–49, and 5–9 age groups at 34363 (95%CI: 6327–66918) per 100,000, 22307.72 (95%CI: 1380–47442) per 100,000, and 18020(95%CI: 1093–37266) per 100,000, respectively. Conclusions: In 2023, the actual pertussis infection rate in the population of Huzhou City was relatively high. Vaccine-induced antibodies exhibit a rapid decay, and the estimated serum infection rate increases rapidly from post-school age, peaking in the 20–29 age group. It is recommended to enhance pertussis monitoring in adolescents and adults and refine vaccine immunization strategies. [ABSTRACT FROM AUTHOR]

The structural evolution of lone-pair compounds under high-pressure and high-temperature conditions has been a subject of fundamental interest in revealing modulated polymorphs. As one of the archetypal lone-pair compounds, selenium dioxide (SeO2) has attracted much attention due to the pressure modulation of its one-dimensional infinite W-shaped chain arrangement. Here, through swarm intelligence algorithm in conjunction with the first-principles simulation, we propose the existence of an orthorhombic Pnma-SeO2 structure, characterized by V-shaped chains interconnected via vertex-sharing SeO3 pyramids. These V-shaped chains demonstrate reduced compressibility along their chain direction compared to the W-shaped chains. Calculations indicate that Pnma-SeO2 is a semiconductor with a large indirect bandgap of 2.39 eV. Remarkably, we synthesized the predicted Pnma-SeO2 in a laser-heated diamond anvil cell at a pressure of 48.5 or 87 GPa as identified by in situ synchrotron x-ray diffraction data. Our findings lead to a significant extension of the phase diagram and transition path of SeO2 and provide key insights into understanding the pressure modulation in lone-pair compounds. [ABSTRACT FROM AUTHOR]

Layered trihalides have attracted significant interest due to their potential applications in optical and spintronic devices. Herein, we report a combined experimental and theoretical investigation of antimony tribromide (SbBr3) under high pressure (up to 30 GPa) using synchrotron x-ray diffraction, Raman spectroscopy, alternating current (AC) impedance measurements, and first-principles calculations. The results indicate that SbBr3 transforms from a molecular phase (space group Pbnm) to an eight-coordinated layered phase (space group P21/a) at 7.6 GPa. A partial density of states analysis reveals that the eight-coordinated layered geometry of SbBr3 is rooted in the electron transfer from the Sb p orbital to the Br p orbital. Furthermore, based on AC impedance measurements, the resistance decreases with increasing pressure due to the gradual narrowing of the bandgap of SbBr3 in the Pbnm phase. The positive resistance–pressure relationship in the P21/a phase is attributed to the low carrier mobility caused by lattice distortion. Our current findings not only provide information on the phase diagram and electronic transport of SbBr3 but also expand the realm of layered functional materials in molecular trihalides. [ABSTRACT FROM AUTHOR]

Iron difluoride (FeF2) has attracted considerable attention for its physical characteristics and practical applications, and its compression behaviors usually play a key role in the in-depth understanding of this compound. Since its high-pressure crystal structure evolution determining a more profound comprehension remains disputable, we carried out extensive experiments to focus on the pressure-induced structural phase transitions of FeF2. Through in situ high-pressure synchrotron x-ray diffraction measurements, we not only confirmed a reported high-pressure orthorhombic Pbca phase at 11 GPa but also identified an interesting two-dimensional structure with hexagonal close packed symmetry (P-3m1) that appears above 25 GPa at room temperature. Furthermore, the spontaneous strain fitting and electronic transport measurements suggest that its ambient rutile-type structure (P42/mnm) evolves into an orthorhombic structure (Pnnm) through a second-order phase transition at 5 GPa. These experimental results elaborate on the pressure-induced phase transitions of FeF2 on the order of P42/mnm → Pnnm → Pbca → P-3m1, shedding light on a rare three-dimensional to two-dimensional configuration transition in difluorides. [ABSTRACT FROM AUTHOR]

Hydrogen-abundant compounds, as highly potential candidates of near- or room-temperature superconductors, have recently attracted substantial attention. It is noted that metal-rich hydrides may exhibit unique electride feature, together with potential superconductivity, which indicates that they could be regarded as electride superconductor (ESC) hydrides. Herein, we performed the first-principles structure searches of calcium-rich hydrides for designing ESC hydrides. Strikingly, unprecedented calcium-based hydride Ca2H with robust stability and excellent metallicity is identified under compression, where it possesses the zero-dimensional distribution feature of interstitial electrons serving as interstitial quasiatoms (ISQs), mainly originating from the donation of calcium atoms. Interestingly, cubic Fm3¯m Ca2H, with antifluorite-type configuration, consists of a host Ca sublattice and guests H and ISQs confined in the center of Ca8 cubes. Furthermore, Ca2H is predicted to have a superconducting critical temperature Tc of 6 K at 100 GPa and exhibit significantly enhanced superconductivity up to 11 K when dynamically stabilized to 30 GPa, which is predominantly attributed to the remarkable softening of low-frequency acoustic phonon modes involving Ca-dominated vibrations, accompanied by the strong coupling with Ca 3d states near the Fermi energy. Additionally, the yielded electride Na2H via substituting Ca with Na in Ca2H is found to have a notably high Tc of 46 K at 30 GPa. Our current work improved the understanding of structures and properties of electrides, as well as paving the way for exploring emergent ESCs in hydride systems. [ABSTRACT FROM AUTHOR]