Experimental setup for ground-based measurements in preparing cosmic experiments to study nuclear planetology

An experimental laboratory setup combining various gamma spectrometers and neutron generators that is intended for operating at the experimental nuclear-planetology facility deployed at the Joint Institute for Nuclear Research (Dubna, Russia) in order to perform physical calibrations of active gamma and neutron spectrometers is described.     

Microstructural Features and Electrophysical Characteristics of Ceramic–Crystal Matrix Composites

The electrophysical properties of ceramic–crystal matrix composites are studied. Piezoelectrically active PZT/LiNbO₃ ceramic matrix composites with LiNbO₃ concentrations of 0–20 vol % are fabricated. Complex elastic, dielectric, and piezoelectric parameters are measured, and the microstructural characteristics of the obtained samples are studied experimentally. It is found that the extreme electrophysical properties of ceramic–crystal matrix composites depend on the properties and structure of the piezoceramic matrix and crystalline filler, and on the matrix microporosity produced during sintering. The electrophysical parameters of ceramic–crystal matrix composites as functions of crystalline filler content are established through the competing microporosity growth effects of the ceramic matrix and the increase in crystalline filler content.     

New Techniques and Designs of Focusing Piezoelectric Transducers for Ultrasonic Diagnostics and Therapy

New techniques of forming high intensity focused ultrasound (HIFU) fields using dynamic focusing and harmonic multifrequency excitation are developed for ultrasonic diagnostics and therapy. New designs of HIFU transducers based on high-performance composite materials are developed and studied. Finite-element and finite-difference simulations of HIFU transducers and processes of ultrasonic wave propagation in biological tissues are performed. The parameters of piezoceramic materials, piezoelements, and the acoustic fields of focusing ultrasonic transducers are measured. Experiments are performed on biological tissues ex vivo that confirm the efficiency, selectivity, and safety of the developed HIFU transducers and techniques of forming acoustic fields.     

Elemental Analysis of Engine Parts of the Proton Rocket Carrier with Resonance Neutrons

At the JINR Laboratory of Nuclear Physics, neutron–nucleus interactions are investigated for fundamental and applied purposes using the IREN pulsed neutron source. The applied research includes an elemental analysis of constituent materials of various devices. This paper describes the elemental-analysis techniques employed and reports the measurement of palladium abundances in the engine components of the Proton rocket carrier. The elemental-analysis technique involving resonance neutrons, currently implemented with the Romashka apparatus, is shown to be sensitive to palladium abundances at a level of 2 mg/g for samples with masses on the order of 60 g. Further developing the method will boost its sensitivity and allow for elemental analyses of larger samples and their assemblies.     

Light-induced orientation of the molecules of nematic liquid crystals doped with comb-shaped polymers with different spatial distributions of chromophores

The orienting effect of light on nematic liquid crystals (NLCs) doped with comb-shaped polymers with different spatial distributions of side absorbing azobenzene fragments, i.e., a homopolymer (containing only azofragments), a block copolymer (containing additionally a block of non-absorbing fragments), and a statistical copolymer (containing randomly arranged absorbing and non-absorbing fragments) is experimentally studied. The light-induced Freedericksz transition threshold for the block copolymer is two times lower than that for the homopolymer. For NLC with statistical copolymer dopant, the first-order orientation transition with an extremely wide optical bistability region is observed.     

The LUE-200 accelerator at the IREN facility: Current status and development

The general scheme and current status of an electron linear accelerator with an S-band travelling wave (f = 2856 MHz) accelerating structure—a driver for a pulsed neutron source (the Intense Resonance Neutron source (IREN)) at the Frank Laboratory of Neutron Physics of the Joint Institute for Nuclear Research—are presented. The parameters of the accelerating system and the measured parameters of the electron beam—pulse-beam current, duration of the current pulse, repetition rate, electron-energy spectrum, and loading characteristics of the accelerating structure—are given. The beginning of the implementation of the project of the second stage of the IREN facility, which forms the basis for the development of the accelerator aimed at increasing its beam power, is reported. Technical solutions underlying the modernization of the accelerator’s electrophysical systems are discussed: accelerating system, RF power supplies, and modulators.     

Effect of the shape of metal solids on the rate of their joule heating in electromagnetic rail launchers

This paper presents a method and results of numerical simulations of current-density, magnetic-field, and temperature distributions in rail launchers of conducting solids for armatures of various shapes. A comparison is made of the results of calculations using two-dimensional and three-dimensional models. It is shown that for cylindrical and saddle-shaped armatures, Joule heating calculations performed by two-dimensional simulation of electromagnetic and thermal phenomena are in good agreement with calculations for the three-dimensional model. __________ Translated from Prikladnaya Mekhanika i Tekhnicheskaya Fizika, Vol. 50, No. 2, pp. 205–216, March–April, 2009.     

Supramolecular Complexes of Tetrapeptides Capable of Inducing the Human α-Lactalbumin β-Domain Conformational Transitions

Crystallography Reports - It is shown using small-angle X-ray scattering (SAXS) that the tetrapeptide, which is an inductor of fibrillogenesis for a fragment of α-human lactalbumin...     

Transamination of aminohydroxypyrimidines

Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 4, p. 975, April, 1989.     

Improvement of the control of analytical work in the chemical sampling of gold ore deposits

A procedure for the control of analytical work in the chemical sampling of gold ore deposits is proposed to increase the efficiency of the control of analytical work.