Enthalpy of mixing in the propylene oxide–dimethylformamide and propylene oxide–ethylene glycol systems

Heat of mixing of propylene oxide with N,N-dimethylformamide and ethylene glycol has been determined by means of microcalorimetry. Theoretically suggested choice of the aprotic solvent as a selective separating agent for the propylene oxide–methanol binary mixture has been experimentally justified.     

Giant intrinsic carrier mobilities in graphene and its bilayer

We have studied temperature dependences of electron transport in graphene and its bilayer and found extremely low electron-phonon scattering rates that set the fundamental limit on possible charge carrier mobilities at room temperature. Our measurements show that mobilities higher than 200 000 cm2/V s are achievable, if extrinsic disorder is eliminated. A sharp (thresholdlike) increase in resistivity observed above approximately 200 K is unexpected but can qualitatively be understood within a model of a rippled graphene sheet in which scattering occurs on intraripple flexural phonons.     

Efficiency of a planar diode with an explosive emission cathode under the conditions of delayed plasma formation

The energy and current balances in the diode unit of a high-current pulsed electron accelerator (350–500 keV, 60 ns, 250 J per pulse) are compared for an explosive emission cathode (made of graphite, copper, or carbon felt) and a multipoint (graphite or copper) cathode. The planar diode with the continuous cathode is shown to be more efficient in terms of conversion of the applied energy to electron energy (more than 90%) despite a delay in the plasma surface formation. With the impedance of the planar diode matched to the output resistance of the nanosecond generator, the efficiency of the diode does not depend on the time of plasma formation on the cathode. In the case of the graphite cathode, the plasma formation delay reduces the fraction of slow electrons in the forming electron beam and reduces electron losses in anode foil when the beam is extracted from the vacuum space of the diode chamber into the reactor.     

Orbital Selective Localization Enhancement in Ca2 – xSrxRuO4

JETP Letters - The combination of density functional theory with dynamic mean field theory (DFT + DMFT) was applied for the investigation of the magnetic properties of Ca2 – xSrxRuO4. We...     

Development and Study of Composite Acoustic Resonators with Al/(Al,Sc)N/Mo/Diamond Structure with a High Q Factor in the UHF Range

Acoustical Physics - The paper demonstrates for the first time the possibility of using aluminum nitride–scandium as an effective piezoelectric material in composite acoustic resonators on...     

Synthesis of a Water Dispersion of the PEDOT:PSS/Pd Composite and Its Use for the Fabrication of an Electrochemical Sensor for Hydrazine

Conditions are studied for the synthesis of water dispersions of polymer composites containing palladium and the possibility of their use for the fabrication of modified electrodes is estimated. Water dispersions of the polymer poly(3,4-ethylenedioxythiophene), including a polystyrene sulfate polyanion (PEDOT:PSS) and Pd particles, were obtained by the redox reaction of Pd(II) with the polymer. The electrochemical behavior of composite PEDOT:PSS/Pd films in the medium of a phosphate buffer solution with pH 6.86 is studied. It is shown that, in the presence of hydrazine in a phosphate buffer solution, one wave of hydrazine oxidation on metal inclusions, Pd particles, is observed on the electrode. Specific features of the process of hydrazine oxidation are studied and a possibility using the obtained material for the creation of an electrochemical sensor for hydrazine is demonstrated.     

Phase formation in the ScPO4-Na3PO4-Li3PO4 ternary system

The 950°C isothermal section of the ScPO₄-Na₃PO₄-Li₃PO₄ three-component system was plotted and studied; one-, two-, and three-phase fields were bounded. Three solid solution fields exist in the title system: one based on LiNa₅(PO₄)₂ complex phosphate (olympite structure), another on scandium-stabilized high-temperature Na₃PO₄ phase Na_{3(1 − x)}Sc _x/3□_2/3x PO₄ (space group Fm3m), and the third on Na₃Sc₂(PO₄)₃ (NASICON structure). All phases found in the title system are derivatives of phases that exist in its subsystems. Lithium-for-sodium isovalent substitutions in Na₃Sc₂(PO₄)₃ considerably increase the NASICON-type solid solution field but negatively influence the conductivity of the phase.     

Femtosecond laser writing of subwave one-dimensional quasiperiodic nanostructures on a titanium surface

One-dimensional quasiperiodic structures whose period is much smaller than the wavelength of exciting radiation have been obtained on a titanium surface under the multipulse action of linearly polarized femtosecond laser radiation with various surface energy densities. As the radiation energy density increases, the one-dimensional surface nanorelief oriented perpendicularly to the radiation polarization evolves from quasiperiodic ablation nanogrooves to regular lattices with subwave periods (100–400 nm). In contrast to the preceding works for various metals, the period of lattices for titanium decreases with increasing energy density. The formation of the indicated surface nanostructures is explained by the interference of the electric fields of incident laser radiation and a surface electromagnetic wave excited by this radiation, because the length of the surface electromagnetic wave for titanium with significant interband absorption decreases with an increase in the electron excitation of the material.     

Dirac Quantum Geometrodynamics

Russian Physics Journal - With the help of the Dirac procedure for extracting the root from the Hamiltonian operator of the free gravitational field in flat superspace-time, we have constructed a...