Thermal conductivity of Fe-Si alloys and thermal stratification in Earth's core.

Light elements in Earth's core play a key role in driving convection and influencing geodynamics, both of which are crucial to the geodynamo. However, the thermal transport properties of iron alloys at high-pressure and -temperature conditions remain uncertain. Here we investigate the transport properties of solid hexagonal close-packed and liquid Fe-Si alloys with 4.3 and 9.0 wt % Si at high pressure and temperature using laser-heated diamond anvil cell experiments and first-principles molecular dynamics and dynamical mean field theory calculations. In contrast to the case of Fe, Si impurity scattering gradually dominates the total scattering in Fe-Si alloys with increasing Si concentration, leading to temperature independence of the resistivity and less electron-electron contribution to the conductivity in Fe-9Si. Our results show a thermal conductivity of ∼100 to 110 W⋅m-1⋅K-1 for liquid Fe-9Si near the topmost outer core. If Earth's core consists of a large amount of silicon (e.g., > 4.3 wt %) with such a high thermal conductivity, a subadiabatic heat flow across the core-mantle boundary is likely, leaving a 400- to 500-km-deep thermally stratified layer below the core-mantle boundary, and challenges proposed thermal convection in Fe-Si liquid outer core.

Evolution of Structural and Electronic Properties in NbTe2 under High Pressure.

Transition metal dichalcogenides (TMDs) have attracted wide attention due to their quasi-two-dimensional layered structure and exotic properties. Plenty of efforts have been done to modulate the interlayer stacking manner for novel states. However, as an equally important element in shaping the unique properties of TMDs, the effect of intralayer interaction is rarely revealed. Here, we report a particular case of pressure-tuned re-arrangement of intralayer atoms in distorted 1T-NbTe2, which was demonstrated to be a new type of structural phase transition in TMDs. The structural transition occurs in the pressure range of 16-20 GPa, resulting in a transformation of Nb atomic arrangement from the trimeric to dimeric structure, accompanied by a dramatic collapse of unit cell volume and lattice parameters. Simultaneously, a charge density wave (CDW) was also found to collapse during the phase transition. The strong increase in the critical fluctuations of CDW induces a significant decline in the electronic correlation and a change of charge carrier type from hole to electron in NbTe2. Our finding reveals a new mechanism of structure evolution and expands the field of pressure-induced phase transition.

ApoL1 induces kidney inflammation through RIG-I/NF-κB activation.

The genetic variations of the apolipoprotein L1 (APOL1) gene are associated with non-diabetic kidney diseases. However, very little is known about the role of ApoL1 in glomerular damage. Here, we aimed to identify the function and mechanism of ApoL1 in glomerular damage. The mice were randomly divided into two groups: one group was intraperitoneally injected with phosphate buffer saline (PBS), while the other group was intraperitoneally injected with recombinant ApoL1 every other day for 3 months. Hematoxylin and eosin (HE) and periodic acid Schiff (PAS) staining were used to demonstrate the effects of ApoL1 on kidney inflammation and injury. Furthermore, quantitative real-time polymerase chain reaction (qRT-PCR) and enzyme-linked immunosorbent assay (ELISA) analyses revealed that ApoL1-treated mice exhibited enhanced expression of various inflammation markers in the kidney and serum compared to the PBS-treated mice. Immunofluorescence staining revealed that ApoL1 accumulated in kidney podocytes. Treatment with ApoL1 dose-dependently increased the expression of inflammation markers and apoptotic markers. The abnormal gene expression associated with ApoL1-mediated podocyte inflammation was evaluated using microarray analysis. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) analyses revealed that the upregulated genes were enriched in the inflammation-related processes, such as the RIG-I/NF-κB signaling pathway. Consistently, the knockdown of RIG-I significantly mitigated the ApoL1-induced upregulation of inflammatory and apoptotic markers in the human podocytes. Additionally, the ApoL1-induced glomerular damage was attenuated in AAV-shRIG-I mice. Therefore, the effects of ApoL1 on glomerular damage may be, at least partially, through inducing abnormal expression of inflammatory molecules, which may have important implications for treatment of kidney diseases.

Reconciliation of Experiments and Theory on Transport Properties of Iron and the Geodynamo.

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.

Cepharanthine inhibits migration, invasion, and EMT of bladder cancer cells by activating the Rap1 signaling pathway in vitro.

BACKGROUND: Cepharanthine, a bioactive constituent of Stephania japonica (Thunb.) Miers, is known for its potent anti-tumor properties. Nevertheless, the precise impact of this substance on bladder cancer remains poorly comprehended. The aim of this study was to demonstrate the effect and mechanism of cepharanthine on the metastasis of human bladder cancer cells. METHODS: The application of network pharmacology was utilized to ascertain the possible targets and signaling pathways of cepharanthine in the treatment of bladder cancer. The antiproliferative effects of cepharanthine were evaluated using Cell Counting Kit-8 and colony formation assays. The migration and invasion capabilities were assessed using Transwell assays and wound healing experiments. Proteins related to the Rap1 signaling pathway, cellular migration, cellular invasion, and Epithelial-Mesenchymal Transition (EMT) were quantified by western blotting. RESULTS: Through database screening, 313 cepharanthine-acting targets, 277 candidate disease targets in bladder cancer, 22 intersecting targets, and 12 core targets were confirmed. The involvement of the Rap1 signaling system was revealed by the Kyoto Encyclopedia of Genes and Genomes' pathway enrichment study. Cepharanthine was shown to decrease bladder cancer cell proliferation, migration, and invasion in vitro. Cepharanthine activated the Rap1 signaling pathway by upregulating Epac1 and downregulating E-cadherin and C3G protein expression, leading to increased expression of Rap1 GTP protein and decreased expression of protein kinase D1 and integrin α5. Rap1 signalling pathway activation resulted in the downregulation of migration and invasion-related proteins, matrix metallopeptidase MMP2, MMP9, as well as EMT-related proteins, N-cadherin and Snail, without affecting vimentin expression. CONCLUSION: Cepharanthine inhibits migration, invasion, and EMT of bladder cancer cells by activating the Rap1 signalling pathway. The results offer helpful insights regarding the possible therapeutic use of cepharanthine for treating bladder cancer.

Mid-mantle water transportation implied by the electrical and seismic properties of ε-FeOOH.

Water in the mantle transition zone and the core-mantle boundary plays a key role in Earth's stratification, volatile cycling, and core formation. If water transportation is actively running between the aforementioned layers, the lower mantle should contain water channels with distinctive seismic and/or electromagnetic signatures. Here, we investigated the electrical conductivity and sound velocity of ε-FeOOH up to 71 GPa and 1800 K and compared them with global tomography data. An abrupt three-order jump of electrical conductivity was observed above 50 GPa, reaching 1.24(12) × 103 S/m at 61 GPa. Meanwhile, the longitudinal sound velocity dropped by 16.8% in response to the high-to-low spin transition of Fe3+. The high-conductivity and low-sound velocity of ε-FeOOH match the features of heterogenous scatterers in the mid-lower mantle. Such unique properties of hydrous ε-FeOOH, or possibly other Fe-enriched phases can be detected as evidence of active water transportation in the mid-lower mantle.

Temperature-induced amorphization in CaCO3 at high pressure and implications for recycled CaCO3 in subduction zones.

Calcium carbonate (CaCO3) significantly affects the properties of upper mantle and plays a key role in deep carbon recycling. However, its phase relations above 3 GPa and 1000 K are controversial. Here we report a reversible temperature-induced aragonite-amorphization transition in CaCO3 at 3.9-7.5 GPa and temperature above 1000 K. Amorphous CaCO3 shares a similar structure as liquid CaCO3 but with much larger C-O and Ca-Ca bond lengths, indicating a lower density and a mechanism of lattice collapse for the temperature-induced amorphous phase. The less dense amorphous phase compared with the liquid provides an explanation for the observed CaCO3 melting curve overturn at about 6 GPa. Amorphous CaCO3 is stable at subduction zone conditions and could aid the recycling of carbon to the surface.

Reversible switching between pressure-induced amorphization and thermal-driven recrystallization in VO2(B) nanosheets.

Pressure-induced amorphization (PIA) and thermal-driven recrystallization have been observed in many crystalline materials. However, controllable switching between PIA and a metastable phase has not been described yet, due to the challenge to establish feasible switching methods to control the pressure and temperature precisely. Here, we demonstrate a reversible switching between PIA and thermally-driven recrystallization of VO2(B) nanosheets. Comprehensive in situ experiments are performed to establish the precise conditions of the reversible phase transformations, which are normally hindered but occur with stimuli beyond the energy barrier. Spectral evidence and theoretical calculations reveal the pressure-structure relationship and the role of flexible VOx polyhedra in the structural switching process. Anomalous resistivity evolution and the participation of spin in the reversible phase transition are observed for the first time. Our findings have significant implications for the design of phase switching devices and the exploration of hidden amorphous materials.

Solvent effects on geometrical structures and electronic properties of metal Au, Ag, and Cu nanoparticles of different sizes.

Study of the geometrical structures and electronic properties of metal nanoparticles is a very interesting topic. In this work we studied the effects of cyclohexane, benzene, ethanol, and water on bond lengths, Mulliken charge distributions, binding energy (BE), energy gap between highest occupied molecular orbital (HOMO) and the lowest unoccupied molecular orbital (LUMO) (Δ(HL)), ionization potential (IP) and electron affinity (EA) of Au20, Ag20, Cu20, Au38, Ag38, and Cu38 nanoparticles by using density functional theory (DFT). The results indicated that the properties of the solvents influence the geometrical structures and electronic properties of the metallic nanoparticles considerably, and the solvent effect depends on the properties of the solvents, the size of the metal particles, and the category of the metals. Generally, the properties of smaller particles are more sensitive to the change of the solvents, and the polar solvents have larger effect on the properties.