Influence of Annealing in Zinc Vapor on the Microstructure and Activator Radiation of ZnSe : Fe

Crystallography Reports - The effect of thermal treatment in zinc vapor on the stoichiometry, defect and impurity structure, and activator cathodoluminescence of ZnSe doped with iron by the thermal...     

Properties of Langmuir and immobilized layers of betulin diphosphate on aqueous solutions of zinc sulfate and on the surface of zinc oxide nanoparticles

Russian Chemical Bulletin - This work examines the specific features of interaction of betulin diphosphate (BDP), exhibiting antitumor and wound-healing properties, with zinc cations during its...     

Present Status of the Experiment on the Search for Dark Photons by Multi-Cathode Counter

Physics of Atomic Nuclei - We describe the apparatus used in this experiment and the procedure of data treatment. We give the latest experimental results and discuss the possibility to observe...     

High-Intensity-Laser–Matter Interactions: the Energy-Control System of the Pico Laser Facility

We consider the requirements of the energy-control system of the PICO laser facility and describe a design of the calorimeter based on the proposed method of laser-radiation-energy measurements using the calorimeter–sensor thermal response. We present the results of an experimental study of the calorimeter temporal parameters and dynamic analog memory.     

Low-voltage scanning electron microscopy of multilayer polymer systems

The possibilities of low-voltage scanning electron microscopy for visualization of specific features of the microstructure in internal layers of multilayer polymer films are demonstrated by the example of “chitosan–polyelectrolyte complex–alginic acid” composite. The process of electron beam interaction with a sample at low electron energies is considered. The key parameters of low-voltage electron microscopy, which make it possible to increase the resolution of SEM images of polymer systems, are discussed.     

Sensory Rhodopsin I and Sensory Rhodopsin II Form Trimers of Dimers in Complex with their Cognate Transducers

Archaeal photoreceptors consist of sensory rhodopsins in complex with their cognate transducers. After light excitation, a two‐component signaling chain is activated, which is homologous to the chemotactic signaling cascades in enterobacteria. The latter system has been studied in detail. From structural and functional studies, a picture emerges which includes stable signaling complexes, which assemble to receptor arrays displaying hexagonal structural elements. At this higher order structural level, signal amplification and sensory adaptation occur. Here, we describe electron microscopy data, which show that also the archaeal phototaxis receptors sensory rhodopsin I and II in complex with their cognate transducers can form hexagonal lattices even in the presence of a detergent. This result could be confirmed by molecular dynamics calculations, which revealed similar structural elements. Calculations of the global modes of motion displayed one mode, which resembles the “U”‐”V” transition of the NpSRII:NpHtrII complex, which was previously argued to represent a functionally relevant global conformational change accompanying the activation process [Ishchenko et al. (2013) J. Photochem. Photobiol. B 123, 55‐58]. A model of cooperativity at the transmembrane level is discussed.     

Characterization of divinyl benzene aerogels with density gradient using X-ray tomography technique

Production of density gradient aerogels with predetermined density steps or gradient is challenging, particularly when the experiments would demand a prescribed gradient in density along the axis of cylindrical shaped aerogel. In order to achieve this, it is vital to characterize and accurately measure the density gradient in order to “design” synthetic routes to achieve the desired density gradient that can be used in plasma physics experiments using high-energy lasers. X-ray tomography was used for the characterization of these aerogels and it is demonstrated that it is the most reliable and quick method for characterization of gradient density aerogels. Divinyl benzene aerogels samples were synthesized by Lewis acid catalysis and samples were supercritically dried, characterized and their parameters measured to realize that the necessary properties were achieved. The change in density from solid density to 100 mg/cm³ is registered and the accuracy is evaluated.     

Properties of solvate shells and the mobility of ions,according to molecular dynamics data

The solvate shells of an ion, its velocity autocorrelation function, and diffusion coefficient D are found, and the interrelations between them are analyzed. A single ion in the system of atoms of a liquid is considered a model system. The interaction between the ion and atoms of the liquid is described by polarization potential U(r); the interaction between atoms of the liquid alone is described by the Lennard–Jones potential. A classical molecular dynamics method is used. Five solvate shells around the ion are found, and the lifetimes of atoms on each shell are calculated. It is found that the velocity autocorrelation function is of a vibrating nature. The spectrum of the autocorrelator and the frequency of cluster vibrations in a linear approximation are compared. Dependences D on parameters of potential U(r) are found. No dependence D on the ion mass is found; this is explained by solvation. The Einstein–Stokes formula and the HSK approximation are used in discussing the results. It is shown that at small radii of the ion, dependence D on parameters U(r) is described by such a model. When the ion radius is increased, the deviation from this dependence and an increase in D are observed. The results are compared to experimental mobilities of O₂^- and Ar₂⁺ ions in liquid argon.     

Quasi-two-dimensional diamond crystals: Deposition from a gaseous phase and structural–morphological properties

Diamond films predominantly consisting of plane micrometer-size crystallites with a thickness of several dozen nanometers have been deposited from a methane–hydrogen gas mixture activated by a dc gas discharge. The crystallite structure has been studied by scanning and transmission electron microscopy and diffraction. A possible mechanism of formation of plane crystallites during deposition of diamond from the gas phase has been discussed. It has been shown that the results agree with the theoretical concepts of formation of crystals with a face-centered cubic lattice.     

Experience on using titanium as a structural material for a solar neutrino lithium detector

Data obtained by the radiotracer method on a specially designed test bench show that a lithium oxide film serves as a trap for beryllium extracted from lithium. No tangible chemisorption of beryllium on the titanium surface is observed. These finding are used to design and fabricate a lithium detector for solar neutrinos. They will also find application in designing power nuclear facilities with liquid-metal heat carriers.