RESUMEN
Using a density functional theory-based thermal transport model, which includes the effects of temperature (T)-dependent potential energy surface, lattice thermal expansion, force constant renormalization, and higher-order quartic phonon scattering processes, it is found that the recently synthesized nitride perovskite LaWN3 displays strong anharmonic lattice dynamics manifested into a low lattice thermal conductivity (κL ) and a non-standard κL âT-0.491 dependence. At high T, the departure from the standard κL âT-1 law originates in the dual particle-wave behavior of the heat carrying phonons, which includes vibrations tied to the N atoms. While the room temperature κL =2.98 W mK-1 arises mainly from the conventional particle-like propagation of phonons, there is also a significant atypical wave-like phonon tunneling effect, leading to a 20% glass-like heat transport contribution. The phonon broadening effect lowers the particle-like contribution but increases the glass-like one. Upon T increase, the glass-like contribution increases and dominates above T = 850 K. Overall, the low κL with a weak T-dependence points to a new utility for LaWN3 in energy technology applications, and motivates synthesis and exploration of nitride perovskites.
RESUMEN
Thermal transport characteristics of monolayer trigonal prismatic tantalum disulfide (2H-TaS2) are investigated using first-principles calculations combined with the Boltzmann transport equation. Due to a large acoustic-optical phonon gap of 1.85 THz, the four-phonon (4ph) scattering significantly reduces the room-temperature phononic thermal conductivity (κph). With the further inclusion of phonon-electron scattering, κph reduces to 1.78 W mK-1. Nevertheless, the total thermal conductivity (κtotal) of 7.82 W mK-1 is dominated by the electronic thermal conductivity (κe) of 6.04 W mK-1. Due to the electron-phonon coupling, κe differs from the typical estimation based on the Wiedemann-Franz law with a constant Sommerfeld value. This work provides new insights into the physical mechanisms for thermal transport in metallic 2D systems with strong anharmonic and electron-phonon coupling effects. The phonon scattering beyond three-phonon (3ph) scattering and even κe are typically overlooked in computations, and the constant Sommerfeld value is widely used for separating κe and κph from the experimental thermal conductivity. These conclusions have implications for both the computational and experimental measurements of the thermal properties of transition metal dichalcogenides.
RESUMEN
Iron oxide (Fe3O4), a classical magnetic material, has been widely utilized in the field of biological magnetic resonance imaging Graphene oxide (GO) has also been extensively applied as a drug carrier due to its high specific surface area and other properties. Recently, numerous studies have synthesized Fe3O4/GO nanomaterials for biological diagnosis and treatments, including photothermal therapy and magnetic thermal therapy. However, the biosafety of the synthesized Fe3O4/GO nanomaterials still needs to be further identified. Therefore, this research intended to ascertain the cytotoxicity of Fe3O4/GO after treatment with different conditions in HBE cells. The results indicated the time-dependent and concentration-dependent cytotoxicity of Fe3O4/GO. Meanwhile, exposure to Fe3O4/GO nanomaterials increased reactive oxygen species (ROS) levels, calcium ions levels, and oxidative stress in mitochondria produced by these nanomaterials activated Caspase-9 and Caspase-3, ultimately leading to cell apoptosis.
RESUMEN
BACKGROUND/AIMS: Subjects with chronic hepatitis C who fail treatment with interferon-alpha are generally divided into two groups: "relapsers" who normalized serum aminotransferase activity and have undetectable viral RNA during treatment and "non-responders" who do not achieve these results. The aim of this study was to examine retreatment of such subjects. METHODOLOGY: We studied 117 subjects with chronic hepatitis C who failed treatment with interferon-alpha, 87 of whom were "non-responders" and 30 "relapsers." Retreatment was with either interferon-alpha-2b plus ribavirin for 48 weeks or with interferon-alpha-2b plus placebo for 24 weeks followed by 24 weeks of combined therapy. RESULTS: Sustained response rates, defined as undetectable viral RNA in serum 6 months after retreatment, were 53% in "relapsers" and 10% in "non-responders" (P < 0.005). There was no significant difference if ribavirin was given for 24 or 48 weeks. In "non-responders" infected with genotypes other than type 1, 42% achieved a sustained response compared to 5% infected with genotype 1 (P = 0.027; odds ratio 7.09). CONCLUSIONS: Treatment with interferon-alpha-2b plus ribavirin is effective in approximately 50% of "relapsers" and "non-responders" infected with non-type 1 genotypes of hepatitis C virus. This therapy is only marginally effective in "non-responders" infected with genotype 1a or 1b.
