Thermodynamic modeling of oxygen dissolution in uranium mononitride at 900–1400 K

Thermodynamic modeling of oxygen dissolution in uranium mononitride in relation to temperature showed that the solubility limit of oxygen in uranium mononitride monotonically increases from 0.0008 to 0.0092 at. % as the temperature is increased from 900 to 1400 K. The presence of a carbon impurity increases the oxygen solubility in uranium mononitride by a factor of 4–5. The oxygen solubility increases by 20–30% as the stoichiometric coefficient in uranium mononitride containing a carbon impurity is decreased by 0.005.     

Aurora Kinase A Is Involved in Controlling the Localization of Aquaporin-2 in Renal Principal Cells

The cAMP-dependent aquaporin-2 (AQP2) redistribution from intracellular vesicles into the plasma membrane of renal collecting duct principal cells induces water reabsorption and fine-tunes body water homeostasis. However, the mechanisms controlling the localization of AQP2 are not understood in detail. Using immortalized mouse medullary collecting duct (MCD4) and primary rat inner medullary collecting duct (IMCD) cells as model systems, we here discovered a key regulatory role of Aurora kinase A (AURKA) in the control of AQP2. The AURKA-selective inhibitor Aurora-A inhibitor I and novel derivatives as well as a structurally different inhibitor, Alisertib, prevented the cAMP-induced redistribution of AQP2. Aurora-A inhibitor I led to a depolymerization of actin stress fibers, which serve as tracks for the translocation of AQP2-bearing vesicles to the plasma membrane. The phosphorylation of cofilin-1 (CFL1) inactivates the actin-depolymerizing function of CFL1. Aurora-A inhibitor I decreased the CFL1 phosphorylation, accounting for the removal of the actin stress fibers and the inhibition of the redistribution of AQP2. Surprisingly, Alisertib caused an increase in actin stress fibers and did not affect CFL1 phosphorylation, indicating that AURKA exerts its control over AQP2 through different mechanisms. An involvement of AURKA and CFL1 in the control of the localization of AQP2 was hitherto unknown.     

Dynamic transitions from smooth to rough to twinning in dislocation motion

The motion of dislocations in response to stress dictates the mechanical behaviour of materials. However, it is not yet possible to directly observe dislocation motion experimentally at the atomic level. Here, we present the first observations of the long-hypothesized kink-pair mechanism in action using atomistic simulations of dislocation motion in iron. In a striking deviation from the classical picture, dislocation motion at high strain rates becomes rough, resulting in spontaneous self-pinning and production of large quantities of debris. Then, at still higher strain rates, the dislocation stops abruptly and emits a twin plate that immediately takes over as the dominant mode of plastic deformation. These observations challenge the applicability of the Peierls threshold concept to the three-dimensional motion of screw dislocations at high strain rates, and suggest a new interpretation of plastic strength and microstructure of shocked metals.     

Electrochemical properties and dissolution of URu<Subscript>3</Subscript> in nitric acid solutions

The electrochemical properties of URu₃ intermetallic compound (IMC) in 0.5–8 M HNO₃ solutions were studied by linear voltammetry and galvanostatic electrolysis. In 0.5–2 M HNO₃, URu₃ occurs in the passive state at potentials lower than +1.3 V (here and hereinafter, vs. SHE), and in 4–8 M HNO₃, an anodic oxidation peak is observed at potentials from +1.0 to +1.2 V. This process, however, leads to IMC passivation and not to its dissolution. At potentials higher than +1.4 V, URu₃ passes into the transpassive state and starts to actively dissolve. The principal possibility of electrochemical dissolution of IMC at potentials exceeding the transpassivation potential was demonstrated by galvanostatic electrolysis. The rate of uranium leaching during electrolysis depends to a greater extent on the current density than on the HNO₃ concentration and reaches 35 mg cm^–2 h^–1 in 6 M HNO₃ at a current density of 182 mA cm^–2.     

The effect of fullerene C60 on the thermooxidative degradation of a free-radical PMMA studied by thermogravimetry and calorimetry

Thermogravimetric and calorimetric study of the effect of fullerene C₆₀ on the thermooxidative degradation of free-radical poly(methyl methacrylate) revealed three stages in the process.