Processing digital images and calculation of beam emittance (pepper-pot method for the Krion source)

Programs for the pre-processing of photographs of beam images on the mask based on Wolfram Mathematica and Origin software are described. Angles of rotation around the axis and in the vertical plane are taken into account in the generation of the file with image coordinates. Results of the emittance calculation by the Pep_emit program written in Visual Basic using the generated file in the test mode are presented.     

Flux line lattice symmetries in the borocarbide superconductor LuNi2B2C

We compare the results of small angle neutron scattering on the flux line lattice (FLL) obtained in the borocarbide superconductor LuNi₂B₂C with the applied field along the c- and a-axes. For H‖c the temperature dependence of the FLL structural phase transition from square to hexagonal symmetry was investigated. Above 10 K the transition onset field. H ₂(T), rises sharply, bending away from H _c2(T) in contradiction to theoretical predictions of the two merging. For H‖a a first order FLL reorientation transition is observed at H _tr=3–3.5 kOe. Below H _tr the FLL nearest neighbor direction is parallel to the b-axis, and above H _tr to the c-axis. This transition cannot be explained using nonlocal corrections to the London model.     

Problems of Constructing the Nuclotron Virtual Model

Problems connected with the Nuclotron virtual simulation model within MADX are considered. The main objective of the study is a more precise specification of the exiting accelerator model, so that the numerical results obtained using MADX are as close as possible to the experimental data obtained in the last Nuclotron runs. The groups of parameters that bring theoretical calculations closer to the experimental data are found via analyzing the impact of the model characteristics on the numerical results.     

Changes in the secondary structure of highly polymeric DNA and CC(GCC)n-type oligonucleotides under the action of steroid hormones and their complexes with apolipoprotein A I

A small-angle X-ray scattering study showed that the action of tetrahydrocortisol (THC) in complex with apolipoprotein A I (ApoA-I) on DNA leads to local melting of DNA. The most probable site of interaction between this complex and DNA is the (GCC)n-type sequence. Oligonucleotides (duplexes) of this type have been synthesized. It was demonstrated that the interaction of this oligonucleotide with the THC-ApoA-I complex leads to dissociation into complementary oligonucleotides. The latter ones also interact with the THC-ApoA-I complex. The kinetics of this multistep process is presented. The mechanism of interaction between hormones or their ApoA-I complexes and duplex CC(GCC)5.GG(CGG)5Li2 was studied using IR spectroscopy. It was shown that the interaction with THC or the THC-ApoA-I complex leads to the formation of hydrogen bonds between the OH group of the hormone A-ring and the C=O group of cytosine or guanine. Interaction with cortisol or the cortisol-ApoA-I complex leads to the formation of a hydrogen bond with the NH group of cytosine; in addition, THC and cortisol form hydrogen bonds with the PO2 group of the duplex and with the OH group of the monosaccharide. The interaction of ApoA-I with the duplex is accompanied by the formation of hydrogen bonds between the protein NH2 group and the C=O group of cytosine and the P=O group. The order-to-order structural transition takes place in the duplex under the action of THC or cortisol, with THC causing a higher ordering as compared to cortisol. The order-to-disorder structural transition occurs in the duplex under the action of the THC-ApoA-I, cortisol-ApoA-I, or ApoA-I complexes. Shifting the pH of the medium from 7.2 to 6.0 also leads to an order-to-disorder-type structural transition.     

Sas_analyzer software for small-angle X-ray scattering data treatment

New approaches to the analysis of small-angle X-ray scattering data from nanoscale systems based on the optimization and direct multiple shooting methods are presented. A program is developed, which bears on these new approaches and allows a user to model small-angle X-ray diffraction data, introduce collimation corrections, and analyze dispersions in the samples. The program results for a number of typical nanosized systems (sols, catalysts) are reported and the comparison with currently available programs for small-angle data processing is presented.     

Cyclization of unsaturated aldehydes catalyzed by (PPh3)2Co(Ph2PCH2CH2PPh2)

Catalytic cyclization of ,-unsaturated aldehydes (intramolecular hydroacylation) in the presence of (PPh₃)₂Co(Ph₂PCH₂CH₂PPh₂) gives four-membered and five-membered cycloalkanones. Depending on aldehyde structure the selectivity is 90–97% at 10–100% aldehyde conversion.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 11, pp. 2565–2568, November, 1989.     

Correctors’ Magnets for the NICA Booster and Collider

Physics of Particles and Nuclei Letters - The NICA accelerator complex will consist of two injector chains, a new 600 MeV/u superconducting booster synchrotron, the existing superconducting...