Physicotechnological principles of the development of biocompatible magnetic nanoparticles for medicine

Nanodispersive powder of a zinc-substituted magnetite was developed. Functional characteristics (biocompatibility, dispersity, magnetic state) allow us to recommend it for approbation in medical and biological applications. The nature of the investigated field dependencies of magnetization indicates that for particles of 3–13 nm, a superparamagnetic state is realized at room temperature, reflecting the specificity of the small particles’ magnetism.     

Synthesis and stability of sulfur-35 labelled 4-ethylbicyclothiophosphate

Different synthetic routes to the preparation of 4-ethyl-2,6,7-trioxa-1-phosphabicyclo[2,2,2]octane-1-thioxide labelled with sulfur-35 have been investigated since it is of considerable interest as radioligand for neurochemistry. The thiophosphate was successfully synthesized by sulfuration of the corresponding bicyclophosphite by elemental sulfur-35, however the radiochemical purity of the material obtained in this way proves to be low. Convenient methods for synthesis of the thioxide from [³⁵S] thiourea, based on the results of the autoradiolysis of the starting [³⁵S] thiourea, has been discovered giving rise to thioxide with high radiochemical purity. The autoradiolytic stability of the labelled thiophosphate has been studied.M. V. Lomonosov Moscow State University, Moscow 119899, Russia Translated from Khimiya Geterotsiklicheskikh Soedinenii, No 8, pp. 1107–1111, August, 1999.     

Thallium-based high-temperature 2212 superconductor with partial substitution of oxygen by fluorine and of calcium by cerium

Fluorine-and cerium-substituted thallium-based high-temperature 2212 superconductors are synthesized, the limits of solubility of the substitutes are investigated, the critical temperatures of the superconducting transitions are measured, and the local structure is refined using the Mössbauer technique.     

The Korteweg-de Vries equation in a cylindrical pipe

A mathematical model of nonlinear wave propagation in a pipeline is constructed. The Korteweg-de Vries equation is derived by determining asymptotic solutions and changing variables. A particular solution to the model equations is found that has the fluid velocity function in the form of a solitary wave. Thus, the class of nonlinear fluid dynamics problems described by the KdV equation is expanded.     

New Universal Cosmic-Ray Knee near a Magnetic Rigidity of 10 TV with the NUCLEON Space Observatory

Data from the NUCLEON space observatory give a strong indication of the existence of a new universal cosmic ray “knee”, which is observed in all groups of nuclei, including heavy nuclei, near a magnetic rigidity of about 10 TV. Universality means the same position of the knee in the magnetic rigidity scale for all groups of nuclei. The knee is observed by both methods of measurement of particles energy implemented in the NUCLEON observatory—the calorimetric method and the kinematic method Kinematic Lightweight Energy Meter. This new cosmic ray knee is probably connected with the limit of acceleration of cosmic rays by some generic or nearby source of cosmic rays.     

Investigations of the mega-ampere multiwire X pinch

The results of experimental investigations into the dynamics of a plasma produced in the multiwire X pinch at currents up to 2.3 MA are presented. The materials, diameters, and the number of wires are varied. At such currents, the power of the soft x-ray radiation with the photon energy from 1 to 2 keV increases to 120 GW, and, since the size of a hot spot is less than 20 μm, it corresponds to a source brightness of ～10¹⁵ W/(cm² sr). The energy recorded in lines of neon-like molybdenum (in the range of 2.5–3 keV) is higher than 10 J. Hard x-ray radiation detected in experiments with tungsten and molybdenum X pinches has the photon energy ≥800 keV.