Method for registration of solar cosmic rays by detecting neutrons

We consider a method of detecting the ionizing component of solar cosmic rays (SCRs) with energy from tens of MeV to tens of GeV by measuring the energy loss of SCR protons and light nuclei in scintillators and the multiplicity of the local neutron generation in a converter. Scintillation detectors based on stilbene, lithium glass, and solid-state photomultiplier tubes are capable of detecting fast neutrons with a temporal resolution of 10 ns and rejecting the gamma-ray background in the measuring system. The method will allow investigating the nucleon components of primary SCRs in circumterrestrial space.     

A neutron activation study of DNA-Gd nanocrystals

The properties of the cholesteric liquid-crystal dispersion containing deoxyribonucleic acid (DNA) molecules and gadolinium ions are investigated using the neutron activation analysis. The cholesteric structure of the DNA-Gd complex is formed by double-stranded DNA molecules and Gd³⁺ cations in nanoparticles. The DNA concentration in nanoparticles reaches 350 mg/ml. The gadolinium concentration in the DNA-Gd complex is determined using the neutron activation analysis. It is found that the DNA-Gd complex contains approximately 1.5 gadolinium atoms per phosphate group of the DNA molecule. The local gadolinium concentration in the nanoparticle reaches 250 mg/ml.     

Autonomous xenon γ-ray spectrometer for radioecology

A new autonomous xenon γ-ray spectrometer for radiative monitoring is proposed. This instrument has a number of advantages over the semiconductor and scintillation spectrometers that are used in radioecology. The main advantages are simplicity in use and temperature, mechanical, and radiation stability.     

Possibility of radionuclide production for PET diagnostics and brachyteraphy on the INR RAS linac

The technology of radionuclide production for positron-emission tomography on the proton linac of the Institute for Nuclear Research, Russian Academy of Sciences, is considered. A prototype of a combined target unit for production of positron-emitting radionuclides ¹¹C, ¹³N, and ¹⁸F in the proton linac beam is presented. The production of medical isotopes ¹⁰³Pd, ^{124, 125}I, and ¹³¹Cs is briefly discussed.     

New evidence for supernarrow dibaryons production in pd interactions

The analysis of new experimental data, obtained at the Proton Linear Accelerator of INR, with the aim to search for supernarrow dibaryons in the pd↦ppX ₁ and pd↦pdX ₂ reactions is presented. Narrow peaks with an experimental width of 5 MeV at masses of 1904±2, 1926±2, and 1942±2 MeV have been observed in missing mass M _pX1 spectra. In the missing mass M _X1 spectra, the peaks at M _X1 = 966±2, 986±2, and 1003±2 MeV have been found. The analysis of the data obtained leads to the conclusion that the observed peaks in M _pX1 spectra are most likely supernarrow dibaryons, the decay of which into two nucleons is forbidden by the Pauli exclusion principle. An alternative interpretation of the spectra by assuming a decay of the supernarrow dibaryons in “exotic baryon states” with masses M _X1 is discussed. Received: 22 October 2001 / Accepted: 15 November 2001     

Molecular Recognition and Catalysis: from Macrocyclic Receptors to Molecularly Imprinted Metal Complexes

Summary: The results of studying a number of reactions catalyzed by several types of soluble macromolecular catalytic systems capable of selectively binding organic substrates, namely, modified cyclodextrins, calixarenes and dendrimers are presented. The use of modified cyclodextrins as components of a catalytic system in the phenol and benzene hydroxylation by hydrogen peroxide allows one both to increase the catalytic activity and to change significantly the chemical selectivity. Phosphorilated calixarene – Rh catalytic systems was found to be catalytically active in hydroformylation of linear alkenes C₇–C₁₂. The results of experiments on the oxidation of C₇–C₁₆ alkenes show that, when the ligand is the dendrimer molecule, the fraction of forming methyl ketones substantially increases for the substrates C₇–C₉. For the higher alkenes, this effect is not observed.     

Problem of a piston in a plastic medium with cultivation

The article discusses the self-similar problem of the motion of a spherical piston in a medium with dry friction and the differential connection between the first invariant of the stress tensor and the second invariant of the tensor of the deformation rates. For the case of flow with a shock wave, the method of a stationary wave is used to obtain the required relationships at a strong discontinuity. It is disclosed that the velocity of the piston, as well as the relationship between the cultivation coefficients and the dry friction, are determined by the smoothness of the friction.Translated from Prikladnoi Mekhaniki i Tekhnicheskoi Fiziki, No. 5, 86–93, September–October, 1974.     

Design of supramolecular metal complex catalytic systems for petrochemical and organic synthesis

Specific features of the behavior of the supramolecular metal complex catalysts based on calixarenes, cyclodextrins, and dendrimers in the reactions of hydroformylation, Wacker oxidation, hydroxylation of aromatics, 2-naphthol coupling, and oxidative coupling of styrenes and benzene were studied. The factors affecting the catalytic activity and selectivity are discussed. Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 4, pp. 766–778, April, 2008.     

Quantum approach to the description of amplification of radiation from an array of nanotubes

The mechanism of generating terahertz radiation by zigzag-type nanotubes is considered using the two-point unit phase cell. The nanotubes are oriented along the radiation field. The radiation gain factor is estimated and the mechanism of excitation of a nonlinear medium based on a nanotube array is discussed.     

A system for monitoring the radiation effects of a proton linear accelerator

The system for real-time monitoring of radioactivity of a high-current proton linear accelerator detects secondary neutron emission from proton beam losses in transport channels and measures the activity of radionuclides in gas and aerosol emissions and the radiation background in the environment affected by a linear accelerator. The data provided by gamma, beta, and neutron detectors are transferred over a computer network to the central server. The system allows one to monitor proton beam losses, the activity of gas and aerosol emissions, and the radiation emission level of a linear accelerator in operation.