Translating particulate hexavalent chromium-induced chromosome instability from human lung cells to experimental animals, human lung tumors and whale cells.

Lung cancer is a major human health problem. While smoking is the most well-known cause of lung cancer, people who never smoked develop the disease. Understanding how non-tobacco environmental carcinogens cause lung cancer is key to combating this disease. Hexavalent chromium [Cr(VI)] is a well-established human lung carcinogen, but its carcinogenic mechanism is uncertain. Chromosome instability (CIN) is a hallmark of lung cancer and a major factor in Cr(VI)-induced lung cancer. Studies in human lung cells show Cr(VI) induces DNA double strand breaks and suppresses homologous recombination (HR) repair by targeting RAD51, resulting in CIN. We translated these outcomes to rats, as this species develops Cr(VI)-induced lung tumors. We exposed 12-week-old Wistar rats to a single dose of zinc chromate for 24 hours or a weekly dose for 90 days via oropharyngeal aspiration. DNA double strand breaks and HR repair increased in a concentration-dependent manner in rat lungs after 24-hour Cr(VI) exposure. After 90-day exposure, DNA double strand breaks increased, but HR repair decreased. These effects were distinct in bronchioles but muted in alveoli, consistent with Cr(VI)-induced human lung tumors originating in bronchial epithelium. We translated these outcomes to Cr(VI)-associated human lung tumors. DNA double strand breaks significantly increased but RAD51 expression decreased in lung tumors; demonstrating Cr(VI)-induced DNA double strand breaks and HR inhibition persist in tumors. Long-lived whales can experience long-term exposure to environmental contaminants but have low cancer rates. We measured the ability of Cr(VI) to induce DNA double strand breaks, HR repair, and chromosome damage in bowhead whale lung cells. Cr(VI) induced DNA strand breaks in whale cells, but the HR repair response remained intact. Thus, whale cells are resistant to Cr(VI)-induced loss of HR repair with no apparent CIN. These results indicate significant differences in the response of human and bowhead whale lung cells to Cr(VI) exposure. Overall, our studies translate Cr(VI)-induced DNA double strand breaks and HR repair impacts to rat lung tissue, human lung tumors and whale lung cells. Cr(VI) induces DNA double strand breaks and inhibits HR repair in vivo, but does not cause HR repair failure and CIN in whale lung cells

Pressure-driven 4f4f localized-itinerant crossover in heavy-fermion compound CeIn3{\mathrm{CeIn}}_{3}: A first-principles many-body perspective

The localized-itinerant nature of Ce−4f valence electrons in heavy fermion compound CeIn3 under pressure is studied thoroughly by means of the combination of density functional theory and single-site dynamical mean-field theory. The detailed evolutions of electronic structures of CeIn3, including total and partial density of states, momentum-resolved spectral functions, and valence state histograms, are calculated in a wide pressure range where the corresponding volume compression V/V0∈[0.6,1.0] (here V0 is the experimental crystal volume) at T≅116 K. Upon increasing pressure, two strong peaks associated with the Ce−4f states emerge near the Fermi level, and the c−f hybridization and valence state fluctuation are enhanced remarkably. Moreover, the kinetic and potential energies rise, while the occupancy, total angular momentum, and low-energy scattering rate of the Ce−4f electrons decline with respect to pressure. All the physical observables considered here exhibit prominent kinks or fluctuations in V/V0∈[0.80,0.90], which are probably the desired fingerprints for the Ce −4f localized-itinerant crossover

Unraveling exotic 5ff states and paramagnetic phase of PuSn3_3

Plutonium-based compounds establish an ideal platform for exploring the interplay between long-standing itinerant-localized 5$f$ states and strongly correlated electronic states. In this paper, we exhaustively investigate the correlated 5$f$ electronic states of PuSn$_3$ dependence on temperature by means of a combination of the density functional theory and the embedded dynamical mean-field theory. It is found that the spectral weight of narrow 5$f$ band grows significantly and remarkable quasiparticle multiplets appear around the Fermi level at low temperature. A striking $c-f$ hybridization and prominent valence state fluctuations indicate the advent of coherence and itinerancy of 5$f$ states. It is predicted that a 5$f$ localized to itinerant crossover is induced by temperature accompanied by the change in Fermi surface topology. Therefore itinerant 5$f$ states are inclined to take in active chemical bonding, suppressing the formation of local magnetic moment of Pu atoms, which partly elucidates the intrinsic feature of paramagnetic ground state of PuSn$_3$. Furthermore, the 5$f$ electronic correlations are orbital selective manifested themselves in differentiated band renormalizations and electron effective masses. Consequently, the convincing results remain crucial to our understanding of plutonium-based compounds and promote ongoing research.Comment: 9 pages, 7 figure

Temperature dependence of correlated electronic states in archetypal kagome metal CoSn

Hexagonal CoSn is a newly-discovered frustrated kagome metal. It shows close-to-textbook flat bands and orbital-selective Dirac fermions, which are largely associated with its strongly correlated Co-3$d$ orbitals. Because correlated electronic states are easily regulated by external conditions (such as chemical doping, pressure, and temperature), the fate of these kagome-derived electronic bands upon temperature becomes an interesting and unsolved question. In this work, we try to study the temperature-dependent electronic structures of hexagonal CoSn by means of the density functional theory in conjunction with the embedded dynamical mean-field theory. We find that hexagonal CoSn is in close proximity to a Mott insulating state at ambient condition. Special attention is devoted to the evolution of its Co-3$d$ electronic states with respect to temperature. At least six different temperatures (or energy scales), namely $T^{*}$, $T_{\text{FL}}$, $T_{\text{S1}}$ (and $T_{\text{S2}}$), $T_{\text{SF}}$, and $\bar{T}$, are figured out. They are related to stabilization of the "pseudogap" state, emergence of the non-Fermi-liquid phase, onset (and completeness) of the intermediate spin state, occurrence of the spin-frozen phase, beginning of the orbital freezing transition, respectively.Comment: 8 pages, 5 figure