Study of the time-differentiated particle flux density at various distances from EAS axis

The EAS time structure is studied using the enlarged EAS array of the Moscow State University. The time measurements are made using 22 scintillators which form 13 rectanges of 180x190 sq m size covering the entire array area. The array is triggered by a signal of 4-fold coincidences of the pulses from the detectors forming each of the rectangles. The data were obtained during 2200 hours of the array operation in 1984. A total of 816 showers, to which at least 14 of 22 scintillator detectors responded, were selected among all those detected. The coordinates of the EAS axis in the observation plane and the EAS sizes were determined by the maximum likelihood method using a computer on the assumption that the electron LDF is the NKG form. A total of 492 showers in the interval of EAS size Ne = 5x10 to the 6th power - 2x10 to the 8th power (N bar e = 1.7x 10 to the 7th power) with zenith angles theta or = 45 deg and axes within the array are analyzed

Spin Crossover [Fe(qsal)2]X (X = Cl, SCN, CF3SO3) Complexes: EPR and DFT Study

The compounds [Fe(qsal)2]X (X = Cl, SCN, CF3SO3) were synthesized and investigated by electron paramagnetic resonance (EPR). The dependence of the Fe(III) spin state on the type of counterion X and on the temperature was established. On the basis of the density functional calculations, the geometrical parameters of compounds in high- and low-spin states were optimized and the difference in their internal energies was calculated. A correlation between the experimental EPR data and the theoretically calculated energy difference between the high-spin and the low-spin states of the compounds with different anions was obtained. © 2010 Springer-Verlag

The current status of orbital experiments for UHECR studies

Two types of orbital detectors of extreme energy cosmic rays are being developed nowadays: (i) TUS and KLYPVE with reflecting optical systems (mirrors) and (ii) JEM-EUSO with high-transmittance Fresnel lenses. They will cover much larger areas than existing ground-based arrays and almost uniformly monitor the celestial sphere. The TUS detector is the pioneering mission developed in SINP MSU in cooperation with several Russian and foreign institutions. It has relatively small field of view (+/-4.5 deg), which corresponds to a ground area of 6.4x10^3 sq.km. The telescope consists of a Fresnel-type mirror-concentrator (~2 sq.m) and a photo receiver (a matrix of 16x16 photomultiplier tubes). It is to be deployed on the Lomonosov satellite, and is currently at the final stage of preflight tests. Recently, SINP MSU began the KLYPVE project to be installed on board of the Russian segment of the ISS. The optical system of this detector contains a larger primary mirror (10 sq.m), which allows decreasing the energy threshold. The total effective field of view will be at least +/-14 degrees to exceed the annual exposure of the existing ground-based experiments. Several configurations of the detector are being currently considered. Finally, JEM-EUSO is a wide field of view (+/-30 deg) detector. The optics is composed of two curved double-sided Fresnel lenses with 2.65 m external diameter, a precision diffractive middle lens and a pupil. The ultraviolet photons are focused onto the focal surface, which consists of nearly 5000 multi-anode photomultipliers. It is developed by a large international collaboration. All three orbital detectors have multi-purpose character due to continuous monitoring of various atmospheric phenomena. The present status of development of the TUS and KLYPVE missions is reported, and a brief comparison of the projects with JEM-EUSO is given.Comment: 18 pages; based on the rapporteur talk given by M.I. Panasyuk at ECRS-2014; v2: a few minor language issues fixed thanks to the editor; to be published in the proceeding

Time-resolved EPR study of radicals from 2,2-dimethoxy-2-phenylacetophenone in ethylene glycol after flash photolysis

The dynamic behaviour of transient free radicals generated by laser pulse photolysis (with λ = 351 nm) of 2,2-dimethoxy-2-phenylacetophenone (DMPA) in ethylene glycol solutions have been studied by time-resolved EPR at room temperature. A main result of the study is a suitable evaluation method for radical systems with CIDEP in the case of very close hyperfine lines and hence with a overlap of several signals. The evaluation of single EPR time-profile signals requires in this case to take in account also the influence of the near resonance positions, what successfully has been done. The formation and decay of the two spin polarized radicals, 7,7-dimethoxy-benzyl (R1) and benzoyl radical (R2), has been observed. For R1 the relaxation time T2 was determined with a good accuracy and the rate constants k1 and k2 were estimated by fitting the time evolution of the EPR signal at resonance and near resonance positions of the field using the Bloch equations and direct Fourier transform analysis. Radicals from DMPA in the high viscous solvent ethylene glycol have been proved to be an excellent model system for this study however the treatment is applicable also for other systems. © 2002 Elsevier Science B.V. All rights reserved

Seasonal changes of free-radical initiated processes in cyprinids from the middle Volga river basin

The purpose of this research was to study the free radical induced lipid oxidation in the commonest fish species inhabiting the Volga river, in the Middle Volga region of the Russian Federation, de-pending on the seasons of the year. The commonest fish species in the Volga river basin: European carp Cyprinus carpio (L., 1758), sabrefish Pelecus cultratus (L., 1758), common bream Abramis brama (L., 1758), tench Tinca tinca (L., 1758), and common roach Rutilus rutilus (L., 1758) were studied. The level of malondialdehyde and the activity of catalase were investigated in gills, liver, muscles and gonads. The values of molecular oxidative biomarkers in the studied fish species were significantly higher in the summer, suggestinga more active lipid peroxidation. The increase in cata-lase activity in the studied organs may indicate activation of the antioxidant defense system that can positively affect the growth and development of fish

Time-resolved ESR studies on transient radicals photogenerated in solutions of melamine in ethylene glycol

Chemically Induced Dynamic Electron Polarization (CIDEP) spectra of transient radicals generated by laser pulse with λ = 248 nm in solutions of melamine in ethylene glycol have been studied by means of time-resolved (TR) ESR at room temperature. The main products are radicals of the solvent molecules formed through abstraction of hydrogen from ethylene glycol by excited melamine molecules and a melamine radical with attached hydrogen atom on melamine. Parameters obtained from well resolved TR ESR spectra coincide with parameters of radical of ethylene glycol HOC{radical dot}HCH2OH and methylol {radical dot}CH2OH, and an unresolved ESR spectrum was attributed to the melamine radical. The electron spin polarization results from the radical pair mechanism (RPM) involving S-T0 mixing (ST0M) and additionally from a small part of triplet mechanism (TM). In order to establish the possible structure and nature of melamine radical quantum-chemical calculations by the DFT B3LYP method using several different basis sets have been done. The reaction pathway and mechanisms of alcohol and melamine radicals formation are proposed and supported by DFT calculations within B3LYP and CIS(D) methods. Melamine and ethylene glycol free radicals relaxation time T2 was estimated as 1.5 and 0.5 μs, respectively. © 2005 Elsevier B.V. All rights reserved