Interaction of amorphous and crystalline nickel nanoparticles with hydrogen

Nickel nanoparticles were deposited on the surface of highly oriented pyrolytical graphite by laser electrodispersion and precipitation from a solution of reverse micelles. The particles were studied using scanning tunneling microscopy and spectroscopy as well as Auger spectroscopy. The elemental composition of the nanoparticles and specific features of the electronic structure of their surface were determined. Adsorption of molecular hydrogen was also studied.     

Laser generation and electromagnetic detection of normal acoustic waves in ferromagnetic metals

Noncontact generation and detection of normal acoustic waves in a ferromagnetic metal sheet made of the 32NKD alloy are experimentally studied. The main relationships of the parameters of such processes are determined.     

Mirrors in optical schemes of ellipsometers

Expressions for Mueller matrices describing how the reflection from plane mirrors with an arbitrary orientation of the surface affects the polarization are obtained. The expressions can be useful in considering new ellipsometers’ optical schemes containing plane mirrors, as well as mirrors with a nonzero curvature of the surface.     

The new frozen spin target at MAMI

The new frozen spin polarized target for experiments at the polarized beam of the real photon facility A2 of the MAMI accelerator is described. The A2-collaboration at the Mainz Microtron MAMI is measuring photon absorption cross section using circularly and linearly polarized photons up to the energy of 1.5 GeV. The photons are produced in the’ Bremsstrahlungs’ process. In the years 2005/2006 the Crystal Ball detector with its unique capability to cope with multi photon final states was set up in Mainz. Since 2010 the experimental apparatus has been completed by a polarized target. The horizontal dilution refrigerator of the Frozen-Spin Target has been constructed and is operated in close cooperation with the Joint Institute for Nuclear Research in Dubna, Russia. The system offers the opportunity to provide longitudinally and transversely polarized protons and deuteron. In this paper the operation experience of this new Frozen-Spin Target and first results from the runs in 2010 and 2011 are presented.     

The status of MCU-5

The software developed within the framework of the MCU project which implements the Monte Carlo method for solving the transport equations for various kinds of radiation is widely used for calculating nuclear reactors of different types. The final version of MCU-5 is described. The developed libraries of constants are briefly described, and the potentialities of the MCU-5 package modules and the executable codes compiled from them are characterized. Examples of important problems of reactor physics solved with the codes from the MCU family are presented.     

Modification of epoxy binders using cycloaliphatic epoxy imides

The influence of epoxy imide cycloaliphatic epoxy resin EPOX-01 on the rheological properties of the epoxy amine system was investigated. The effect of the amount of amine hardener for solidification process of modified system is evaluated. It is shown that the use of epoxy imide cycloaliphatic resin allows one to obtain materials with improved technological characteristics of film technology (RFI).     

The Dynamics of the Neuropeptide Y Receptor Type 1 Investigated by Solid-State NMR and Molecular Dynamics Simulation

We report data on the structural dynamics of the neuropeptide Y (NPY) G-protein-coupled receptor (GPCR) type 1 (Y1R), a typical representative of class A peptide ligand GPCRs, using a combination of solid-state NMR and molecular dynamics (MD) simulation. First, the equilibrium dynamics of Y1R were studied using ¹⁵N-NMR and quantitative determination of ¹H-¹³C order parameters through the measurement of dipolar couplings in separated-local-field NMR experiments. Order parameters reporting the amplitudes of the molecular motions of the C-H bond vectors of Y1R in DMPC membranes are 0.57 for the Cα sites and lower in the side chains (0.37 for the CH₂ and 0.18 for the CH₃ groups). Different NMR excitation schemes identify relatively rigid and also dynamic segments of the molecule. In monounsaturated membranes composed of longer lipid chains, Y1R is more rigid, attributed to a higher hydrophobic thickness of the lipid membrane. The presence of an antagonist or NPY has little influence on the amplitude of motions, whereas the addition of agonist and arrestin led to a pronounced rigidization. To investigate Y1R dynamics with site resolution, we conducted extensive all-atom MD simulations of the apo and antagonist-bound state. In each state, three replicas with a length of 20 μs (with one exception, where the trajectory length was 10 μs) were conducted. In these simulations, order parameters of each residue were determined and showed high values in the transmembrane helices, whereas the loops and termini exhibit much lower order. The extracellular helix segments undergo larger amplitude motions than their intracellular counterparts, whereas the opposite is observed for the loops, Helix 8, and termini. Only minor differences in order were observed between the apo and antagonist-bound state, whereas the time scale of the motions is shorter for the apo state. Although these relatively fast motions occurring with correlation times of ns up to a few µs have no direct relevance for receptor activation, it is believed that they represent the prerequisite for larger conformational transitions in proteins.     

Gamma-ray emission from thunderstorm discharges

Fine features of gamma-ray radiation registered during a thunderstorm at Tien-Shan Mountain Cosmic Ray Station are presented. Long duration (100-600 ms) gamma-ray bursts are found. They are for the first time identified with atmospheric discharges (lighting). Gamma-ray emission lasts all the time of the discharge and is extremely non-uniform consisting of numerous flashes. Its peak intensity in the flashes exceeds the gamma-ray background up to two orders of magnitude. Exclusively strong altitude dependence of gamma radiation is found. The observation of gamma radiation at the height 4-8 km could serve as a new important method of atmospheric discharge processes investigation.     

Parabolic problems with the Preisach hysteresis operator in boundary conditions

Parabolic initial boundary-value problems coupled (via the boundary condition) with ordinary differential equations whose right-hand side contains the Preisach hysteresis operator are considered. In particular, these problems model thermocontrol processes in chemical reactors, climate-control systems, biological cells, etc. For the Preisach operator with and without time delay, solvability, periodicity of solutions, and global B-attractors are studied.     

Cap representations of G2 and the spin L-function of PGSp6

We give a construction of a family of CAP representations of the exceptional group G ₂, whose existence is predicted by Arthur’s conjecture. These are constructed by lifting certain cuspidal representations of PGS _p6. To show that the lifting is non-zero, we establish a Rankin-Selberg integral for the degree 8 Spin L-function of these cuspidal representations of PGS _p6.