Gas absorption in a thin liquid film flow on a horizontal rotating disk

An analytical model for the rate of gas absorption into laminar non-wavy film flow on a horizontal rotating disk is obtained assuming short contact times. Literature data for the oxygen mass transfer coefficient in a wavy film is correlated by means of the dimensionless numbers deriving from the model. The rate enhancement due to waves is found to vary from 6 to 13 times. It is established that the absorption process in the film on the disk as compared to that in a gravitational wavy film flow can be intensified up to 14 times by means of a moderate rotation speed.     

Temperature dependences of the dielectric properties of lithium-titanium ferrite ceramics

Temperature dependences of the real ?′ and imaginary ?″ parts of the complex permittivity of lithium-titanium ferrite ceramics are measured in the frequency range 10²?10⁶ Hz at different test-signal amplitudes and dc bias voltages. It is found that the dielectric characteristics of the ceramic samples drastically change in narrow temperature ranges. The assumption is made that relaxators whose reorientation is due to tunneling transitions of electrons inside “bivalent iron ion-trivalent metal ion” pairs are involved in polarization processes. Under certain conditions, the reorientation of relaxators can have collective character.     

Formation of E4-Centers (E c – 0.76 eV) in Gallium Arsenide

The paper deals with the effects of the bombarding-electron energy on the velocity of E4 center (E _c – 0.76 eV) formation and the temperature dependences of the efficiency of the latter in a neutral volume and the space-charge region of n–type gallium arsenide. The specimens were Schottky diodes manufactured by depositing titanium onto epitaxial layers of n-GaAs with n = (2–4)·10¹⁵ cm³. The defect concentration was obtained by the DLTS spectroscopy method. It is shown that the number of E4 centers in the total amount of irradiation-induced defects sharply increases with increasing the bombarding-electron energy from 1.3 to 2.2 MeV. It is found out that the velocity of introducing E4 centers into the space-charge region does not depend on irradiation temperature and is by far higher than that in a neutral volume. In the latter, however, this velocity is non-linearly increasing with the irradiation temperature. It is assumed that an E4 center is a complex consisting of two unit defects generated in the adjacent sites of the Ga and As sublattices through a single collision. It is noted that its final configuration is formed as a result of interaction of these defects, which depends on the dynamics of transformation of their primary charge states.     

Selective Protein Hyperpolarization in Cell Lysates Using Targeted Dynamic Nuclear Polarization

Nuclear magnetic resonance (NMR) spectroscopy has the intrinsic capabilities to investigate proteins in native environments. In general, however, NMR relies on non‐natural protein purity and concentration to increase the desired signal over the background. We here report on the efficient and specific hyperpolarization of low amounts of a target protein in a large isotope‐labeled background by combining dynamic nuclear polarization (DNP) and the selectivity of protein interactions. Using a biradical‐labeled ligand, we were able to direct the hyperpolarization to the protein of interest, maintaining comparable signal enhancement with about 400‐fold less radicals than conventionally used. We could selectively filter out our target protein directly from crude cell lysate obtained from only 8 mL of fully isotope‐enriched cell culture. Our approach offers effective means to study proteins with atomic resolution in increasingly native concentrations and environments.     

New solvents for the growth of substituted BaFe12O19 single crystals from high-temperature solutions

The solubility of a series of hexaferrite derivatives of BaFe₁₂O₁₉ in solvents of the system Na₂O-B₂O₃ with oxide ratios of 7:3 and 3:2 has been investigated. The temperature dependences of the saturation concentration in these solvents are determined for ferrites with the nominal compositions Ba_0.8Pb_0.2Fe₁₂O₁₉, BaFe₁₀Ga₂O₁₉, BaFe₁₀Al₂O₁₉ and BaFe₈Mn₂ Ti₂O₁₉. Single crystals of BaFe₁₂O₁₉, in which part of the metal ions are replaced by various amounts of Pb²⁺, Ga³⁺, Al³⁺ and Mn²⁺ + Ti⁴⁺ ions, are g rown from the solutions by the slow cooling technique. The distribution coefficients of the substituting ions and the compositions of the crystals obtained are established by microprobe analysis (EPMA). Information on the position of substitution is obtained from the Mössbauer spectra.     

On the integrability of Hamiltonian 1:2:2 resonance

Nonlinear Dynamics - We study the integrability of the Hamiltonian normal form of 1:2:2 resonance. It is known that this normal form truncated to order three is integrable. The truncated to order...