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Publications
Publications (370)
Based on some recent experimental evidence, kinetics of cluster growth in a fullerene C60 low-polar solution are considered within a model based on oxides C60Ox as aggregation initializers. A system of equations for the time-evolution of the cluster-size distribution function is developed. First stage of clusters growth consists in formation of pac...
Fullerene and fullerene like nanostructures play a main role in various research areas. Theamount of investigations of fullerene C60 and C70 has grown up considerably due to their several unique properties [1-2, 6]. In this report we present theoretical models for cluster growth, the modeling of small angle neutron scattering curves, and the result...
Nanodiamonds combine unique mechanical, thermodynamic and optical properties of diamond with the peculiarities of colloidal dimensions and wide possibilities of chemical modification of their surface. Of particular practical interest is the presence of a branched porous structure inside detonation nanodiamond agglutinates in powders. Application of...
The IBR-2 (JINR) pulsed reactor is used in the field of solid state physics for experiments on extracted beams. It is predicted that the IBR-2 reactor will reach resource limits in 2032–2037. To keep and develop beam research at JINR, the development of a new pulsed neutron source has begun. According to estimates, the reactor will have average the...
Thin films of polystyrene-fullerene C60 and C70 nanocomposites are investigated by X-ray, neutron reflectometry and AFM. These films were prepared by spin coating from toluene solutions with fullerene content of 1, 3, and 5 wt % relative to polystyrene mass. The concomitant to spin-coating formation of aggregates, larger for C70, was observed. Stil...
Neutron reflectometry is a method for measuring the spatial profile of the neutron interaction potential with the medium. The interaction potential is the sum of neutron interaction potentials with separate isotopes of the medium. To determine the neutron interaction potential with the structure units, secondary radiation is simultaneously register...
The heating effect in the temperature interval of 20―70 °C on the aggregate structure in aqueous ferrofluids is analyzed basing on the data of small-angle X-ray (SAXS) and neutron (SANS) scattering. Samples prepared according to the same stabilization procedure (double-layer surfactant coating) but with different dispersed magnetic materials (magne...
Fullerenes tend to form clusters in different solutions. In this work, a brief survey and some results in the field of investigations of the structure and kinetics of clusters growing in C60 solutions are presented. The general character of this phenomenon for fullerenes is emphasized, and the considerations of mechanisms responsible for the format...
Conventional small-angle neutron scattering (SANS) and ultrasmall-angle neutron scattering (USANS) are applied in the combined analysis of aggregated silica particles formed in basic tetraethoxysilane/ethanol/water solutions. The scattering is followed for different water/TEOS molar ratios to make a self-consistent description of fractal and size c...
The structure of detonation nanodiamond aqueous dispersions grafted by europium or gadolinium atoms was investigated by small-angle neutron scattering over a wide size scale from 1 to 3000 nm. Similar to the previous studies of nanodiamond suspensions, a strong association of the particle into developed aggregates was revealed. While the characteri...
The work presents the results of studying the structure of binary liquid nanocarbon systems obtained by mixing hydrosol of detonation nanodiamond and aqueous dispersions of single layer graphene oxide flakes. We studied size and space distribution of nanocarbon clusters formed upon interaction of the components in aqueous media by mutually compleme...
Neutron reflectometry is a method for measuring of the spatial dependence (profile) of the potential interaction between neutron and medium. At interface of media the interaction potential is the sum of the elements potentials. For definition of potentials of separate elements (isotopes) a secondary radiation is recorded. Recording channels of seco...
We performed a comparative study of magnetic proximity effects in [Gd(5nm)/Nb(25nm)] 12 and [Cu 30 Ni 70 (6nm)/Nb(27nm)] 12 superlattices of S/F type by means of transport measurements and neutron scattering. Transport measurements have shown that Gd/Nb and CuNi/Nb superlattices shows 3D and 2D type of superconductivity respectively. In the case of...
The influence of the concentration of components in a tetraethyl orthosilicate (TEOS)–water–ethanol mixture on the growth of silicate aggregates in a basic environment is studied with small-angle neutron scattering. There is a general increase in the size of aggregates with an increase in the amount of both water and TEOS. At the same time, when th...
Investigations of aggregation and associated kinetic effects, proceeding in various solutions of fullerenes C60 present a general interesting subject of research for the last 20–30 years. Since the discovery of fullerene solubility in liquids of different polarity, and also proposition of several methods for their dispersion in water media, these s...
The general interest in carbon nanomaterials is related to the wide possibilities of their functionalization for a variety of practical, including biomedical, applications. This class of substances includes ultra-fine nanodiamonds of detonation synthesis, which are formed as a result of the explosion of oxygen-unbalanced explosives in an inert medi...
The toxicity of C60(OH)30, C70(OH)30, and C120O(OH)n fullerenols, prepared by a new original method, has been studied. This method allowed us to obtain high-purity fullerenols and eliminate the risks of synthesis of preparations containing insoluble fractions contaminated with impurities such as fullerenes not completely reacted by hydroxylation. A...
The structure of aqueous solutions of the Phospholipovit medicine, intended for transport of water-insoluble molecular drugs, has been investigated by small-angle neutron scattering. Phospholipovit can also be used alone, for example, in case of acute poisoning. When processing experimental data, neutron reflectometry was additionally applied to de...
An ionization chamber is installed to the REMUR neutron spectrometer, situated at channel no. 8 of the IBR-2. A layered structure containing a layer of the isotope under study with a thickness of several nanometers is placed into the chamber. A neutron beam enters the chamber and is incident on the structure. The reflected neutron beam and the neut...
We have used spin-polarized neutron reflectometry to investigate the magnetization profile of superlattices composed of ferromagnetic Gd and superconducting Nb layers. We have observed a partial suppression of ferromagnetic (F) order of Gd layers in [Gd(dF)/Nb(25 nm)]12 superlattices below the superconducting (S) transition of the Nb layers. The am...
An inevitable consequence of the growth of applications and corresponding production of fullerenes is the accumulation of these molecules in natural aquatic environments and biological systems. This raises the issue of evaluating toxicity of fullerenes and its relation to physical characteristics of fullerene solutions under various conditions. The...
We have used spin-polarized neutron reflectometry to investigate the magnetization profile of superlattices composed of ferromagnetic Gd and superconducting Nb layers. We have observed a partial suppression of ferromagnetic (F) order of Gd layers in [Gd($d_F$)/Nb(25nm)]$_{12}$ superlattices below the superconducting (S) transition of the Nb layers....
A theoretical description is presented for the critical effect of decrease of average cluster size in solutions when diluting with water. This effect, found experimentally for C60 solutions in N-methylpyrrolidone, consists in an abrupt decrease in the size of clusters, when the volume fraction of added water is greater than a certain threshold valu...
Small-angle X-ray scattering (SAXS) is used to characterize the vesicular structure of the phospholipid transport nanosystem (PTNS) at PTNS concentrations in water of 25, 31.25, and 37.5% (w/w). The average vesicle radius, size polydispersity, bilayer thickness, and internal structure are determined from the experiment using two models for the phot...
We propose a method for calculating the evolution of the cluster-size distribution functions of fullerene C60 aggregates in polar solutions within the previously developed limited growth model. This method allows calculation of the distribution function f(r,t) at arbitrary moments of time for the given parameters of the system. As an example, we ca...
A physical model of a high-flux neutron source based on a deep subcritical (keff = 0.96) two-stage booster driven by a proton accelerator with the energy of 600 MeV and beam power of 0.3 MW is proposed. It is shown that the thermal neutron flux density will be comparable to the flux density at the European Spallation Source (ESS) with the proton be...
The design principles and parameters of a promising neutron source, based on the fission reaction of the isotope ²³⁷Np, for use in research in extracted beams are presented. Such a source can operate as a pulsing reactor or super-booster or as a super-booster multiplying the neutrons from the target of a proton accelerator by using a reactivity mod...
The impact of the addition of a polymer (polyethylene glycol) with a molecular weight of 20 kDa on the structure of micellar systems of an anionic surfactant (sodium oleate) in aqueous solutions is investigated via small-angle neutron scattering. The structure and interaction parameters of micelles (micelle aggregation number, degree of ionization,...
The parallel Asynchronous Differential Evolution (ADE) method with adaptive correlation matrix (ACM) is utilized for numerical solution of the global minimization problem within the Separated Form Factors model (SFF) for analysis of structure of the drug-delivering phospholipid transport nanosystem (PTNS). In this framework, parameters of the SFF m...
The two-level organization of C60 fullerene clusters in solutions of C60 in pure toluene and toluene/N-methyl-2-pyrrolidone solvent mixtures is studied by small-angle X-ray scattering (SAXS). The SAXS data for freshly prepared solutions are compared with the data obtained by dynamic light scattering, a technique we use to assess the temporal stabil...
The aim – to review and analyze the data on the long-term population-based efficiency of the screening procedures and other measures implemented according to Stage 1 periodical health checkup in the Russian Federation (by Order №36ан of 2015).
Material and methods. This systematic search was carried out independently by two authors who used four da...
Structural aspects of powders containing magnetic nanoparticles Fe3O4/CoFe2O4 with the anticipated “core-shell” structure are considered by means of comparative analysis with individual particles of Fe3O4, CoFe2O4 in accordance of data obtained from X-ray powder diffraction and small-angle scattering of X-ray (synchrotron) radiation and neutrons. I...
The principles of designing a subcritical neutron-multiplying system with reactivity modulation, which can be used as the target in a superbooster with a linear proton accelerator, are described. Calculations demonstrate that the output neutron-flux density of a pulse can be expected to reach 10¹⁷ cm–2 s–1 at maximum and 2 × 10¹⁴ cm–2 s–1 on averag...
The small-angle neutron scattering technique (SANS) is employed for investigation of structure of the phospholipid transport nanosystem (PTNS) elaborated in the V.N.Orekhovich Institute of Biomedical Chemistry (Moscow, Russia). The SANS spectra have been measured at the YuMO small-angle spectrometer of IBR-2 reactor (Joint Institute of Nuclear Rese...
We report on a study of the structural, magnetic and superconducting properties of Nb(25nm)/Gd($d_f$)/Nb(25nm) hybrid structures of a superconductor/ ferromagnet (S/F) type. The structural characterization of the samples, including careful determination of the layer thickness, was performed using neutron and X-ray scattering with the aid of depth s...
We report on a study of the structural, magnetic and superconducting properties of Nb(25nm)/Gd($d_f$)/Nb(25nm) hybrid structures of a superconductor/ ferromagnet (S/F) type. The structural characterization of the samples, including careful determination of the layer thickness, was performed using neutron and X-ray scattering with the aid of depth s...
We present a theoretical approach based on nonequilibrium thermodynamics and used to describe the kinetics of the transition from the liquid to the glassy state (glass transition). In the framework of this approach, we construct kinetic equations describing the time and temperature evolution of the structural parameter. We discuss modifications of...
Small-angle neutron scattering has been applied to observe a cluster structure and specify its growth in ethanol-based solutions of hydrolyzed silicon tetraethoxide. The contrast variation has been used to reveal the inner structure of the clusters and compare it with the data of the previous analogous experiments. The presence of hydroxyl groups i...
A new time-of-flight neutron reflectometer GRAINS with a horizontal sample plane (vertical scattering plane) has recently been put into operation at the pulsed reactor IBR-2 (JINR, Dubna). The scattering geometry applied makes it possible to carry out complex studies of nanostructured interfaces in solid and liquid states by measuring the specular...
The upper limit of the density of the thermal neutron flux from pulsed sources based on the fission reaction is established. Three types of sources for research on ejected beams are considered: a multiplying target of the proton accelerator (a booster), a booster with the reactivity modulation (a superbooster), and a pulsing reactor. Comparison wit...
We have proposed a real-time method of neutron reflectometry. The magnetic state of the Ta/V/FM/Nb/Si ferromagnetic–superconducting system has been analyzed. Relaxation of the inhomogeneous magnetic state with a characteristic time of several hours, which depends on the magnetic field magnitude and temperature, has been observed. The relaxation of...
The improved X-ray optical scheme, the system of registration, and the measurement procedure of the multifunctional synchrotron radiation spectrometer in the dispersive EXAFS mode are described. The results of the spectrometer energy resolution measurements are given. The advantages and disadvantages of traditional and dispersive EXAFS spectrometer...
The influence of superconductivity on ferromagnetism in the layered Ta/V/Fe1–xVx/V/Fe1–xVx/Nb/Si structures consisting of ferromagnetic and superconducting layers is studied using polarized neutron reflection and scattering. It is experimentally shown that magnetic structures with linear sizes from 5 nm to 30 μm are formed in these layered structur...
The presented work continues the investigation of the problems connected with modeling of the kinetics of polymers glass transition in a wide range of temperature change rates. In our previous work Tropin et al. (2015) , an attempt to model a big set of heat capacity curves of polystyrene glass transition has been made, and the inability of the com...
The C60 and C70 fullerene-cluster size distribution in aqueous solutions and a physiological medium is studied via dynamic light scattering. The initial aqueous solutions of fullerenes obtained via different methods are found to contain clusters with a characteristic size of about 100 nm. The additional aggregation of fullerenes is observed after t...
An overview of the main scientific areas of condensed matter research, which are extended with the use of the IBR-2 high-flux research reactor, is presented. It is demonstrated that the spectrometer facility of the upgraded reactor has great potential for studying the structural, magnetic, and dynamical properties of novel functional materials and...
Experimental data on the small angle synchrotron X-ray scattering (SAXS) are analyzed on a basis of Separated form factors method (SFF) for a study of the drug delivery Phospholipid Transport Nano System (PTNS). Basic parameters of polydispersed population of PTNS nanoparticles (average radius of PTNS-particles, polydispersity of radius, thickness...
The current capabilities of and major scientific problems solved by time-of-flight neutron diffraction are reviewed. The reasons for the rapid development of the method over the last two decades have been mainly the emergence of thirdgeneration pulsed sources with a megawatt time-averaged power and advances in neutron optical devices and detector s...
The kinetics for the dissolution of fullerene C 60 in N-methyl-2-pyrrolidone (NMP) solvent are investigated through measurements of the stirring speed and temperature dependence of the UV-Vis absorption spectra. We develop a model for the kinetics of simultaneously occurring processes in the solution, employing a system of simple kinetic equations...
This paper reviews glass transition kinetics models that are developed to describe the formation of structural (for example, covalent and metallic) glasses, as well as to account for the transition of a polymer to a solid glassy state. As the two approaches most frequently used over the last decade to model the glass transition, the Tool-Narayanasw...
Abstract—The structures of ferrofluids (FFs) based on nonpolar solvent decahydronaphthalene, stabilized by saturated monocarboxylic acids with hydrocarbon chains of different lengths, C16 (palmitic acid) and С12 (lauric acid), with an excess of acid molecules, have been studied by small-angle neutron scattering. It is found that the addition of aci...
Peculiarities of the formation of a neutron enhanced standing wave in the
structure with a thin highly absorbing layer of gadolinium are considered in
the article. An analogue of the poisoning effect well known in reactor physics
was found. The effect is stronger for the Nb/Gd/Nb system. Despite of this
effect, for a Nb/Gd bilayer and a Nb/Gd/Nb tr...
A review of neutron scattering researches of various magnetic fluids (ferrofluids) is made. Advantages and disadvantages of other complementary methods for the structure characterization of ferrofluids are discussed. The small-angle neutron scattering (SANS) method with a wavelength of 0.1–1 nm is a classic example of applying radiation to the dete...
The results of researches concerning the cluster state in a number of disperse carbonic materials that are widely used in modern applications, including fullerenes and detonation nanodiamonds, are reported. With the help of the small-angle neutron scattering (SANS) method, some basic aspects of clustering in such systems are elucidated. At the same...
The possibilities of an isotope-indentifying study of layered structures in different regimes of a neutron wave field are considered. The detection of specularly reflected neutrons and secondary radiation (caused by neutron capture) in the form of charged particles, γ quanta, and nuclear fission fragments, as well as neutrons spin-flipped in a nonc...
The dissolution kinetics of fullerene C60 in solvents with different polarities, including toluene, benzene, and N-methylpyrrolidone (NMP), at varying concentrations and temperatures of the solution, and conditions of preparation, is studied by UV-Vis spectroscopy. For a polar C60/NMP solution, stable peaks in the absorption spectrum were not found...
In this paper, two types of fullerene C60 solutions are compared with respect to their structural features and toxic properties. The results are discussed in terms of their potential in medical and biological applications. The fullerene cluster state at the nanoscale in these solutions is analyzed by small-angle neutron scattering. Experiments on t...
The structure of a polydispersed population of unilamellar dimyristoylphosphatidylcholine (DMPC) vesicles in sucrose solutions has been investigated by small-angle neutron scattering (SANS) and small-angle X-ray scattering (SAXS). Calculations within the model of separated form factors (SFF) show that the structure of the vesicle system depends str...
The phenomenon of neutron channeling in layered structures is considered. Experimental data for the neutron channeling length in layered Cu/Ti/Cu structures obtained in Dubna (Russia) and Grenoble (France) in 2000–2002 are presented. A conclusion about the necessity of further studies of neutron channeling in multilayer structures is drawn.
Particles with a diffusive surface, characterized by a deviation from the Porod power-law asymptotic behavior in small-angle scattering towards an exponent below −4, are considered with respect to the polydispersity problem. The case of low diffusivity is emphasized, which allows the description of the scattering length density distribution within...
The aggregate growth in a C60/N-methylpyrrolidone (NMP) solution has been considered in the framework of the approach developed earlier for describing the cluster growth kinetics in fullerene polar solutions. The final cluster size distribution functions in model solutions have been estimated for two fullerene aggregation models including the influ...
Structural parameters of the magnetite-oleic acid-decalin magnetic fluid at various excesses of oleic acid (up to 25 vol %) have been determined using small-angle neutron scattering. Based on the comparison of the behavior of oleic acid in the magnetic fluid and in the pure solvent (decalin), it has been concluded that the interaction between the m...
The structure of filament amyloid aggregates of hen egg white lysozyme in water has been investigated by the small-angle X-ray scattering method. The experimental data are described by different cylindrical models, among which the best agreement is reached with the long helix model. A comparison of the results with the small-angle neutron scatterin...
Non-polar magnetic fluid systems with an excess of surfactants have been studied with the use
of the small-angle neutron scattering technique. Two types of highly stable ferrofluids, magnetite/
oleic acid/decalin and magnetite/myristic acid/decalin, with a low (of about 1 vol.%)
magnetite content and various acid fractions (up to 25 vol.%) are exam...
![Schematic view of a developed DND cluster (as concluded in [21]) in...](profile/Leonid-Bulavin/publication/256929781/figure/fig1/AS:11431281208268521@1701391951927/Schematic-view-of-a-developed-DND-cluster-as-concluded-in21-in-liquid-dispersions_Q320.jpg)
A spatial transition of the carbon state in detonation nanodiamond (DND) from crystalline diamond inside the particle to a graphite-like state at the DND surface is proposed on the basis of small-angle neutron scattering (SANS) analysis. The SANS contrast variation from concentrated (5 wt%) dispersions of DND in liquids (water, dimethylsulfoxide) r...
The capabilities of the small-angle neutron scattering (SANS) method for the research of various magnetic fluids with low magnetite concentrations (~0.1 vol.%), when the structural factor effect is absent, have been considered. The structural parameters of nanoparticles (the magnetic coherent scattering length density, thickness of a nonmagnetic la...
Here we report on a feasibility study aiming to explore the potential of
Polarized Neutron Reflectometry (PNR) for detecting the inverse proximity
effect in a single superconducting/ferromagnetic bilayer. Experiments,
conducted on the V(40nm)/Fe(1nm) S/F bilayer, have shown that experimental spin
asymmetry measured at T = 0.5TC is shifted towards h...
Factors affecting the determination of the structural parameters of polydisperse particles of typical magnetic fluids (MFs) from small-angle neutron scattering data (SANS), including the possible anisotropy of the particle shape and the residual incoherent background, are analyzed. It is shown that the effect of particle anisotropy on scattering mu...
Non-reversible changes in the UV–Vis spectra (solvatochromism) of C60 fullerene in the binary solvent N-methyl-2-pyrrolidone/toluene are observed when varying the mixture composition. The solvatochromism strongly depends on the order of the mixture preparation. We attribute the effect to a great difference in the polarity of the liquid components,...
The helical structure of amyloid protofilaments of hen egg white lysozyme was analyzed by small-angle neutron scattering (SANS) and atomic force microscopy (AFM). The structure of these formations in bulk solutions was adequately described by SANS in terms of a simplified model of a helix with spherical structural units. The found main helix parame...
Powders of magnetic nanoparticles coated by biocompatible block copolymers (substituted pyrroles) are investigated by small-angle neutron scattering. It is found that the structure of the final precipitates depends on the type of stabilizing shell in the initial magnetic fluids. When dodecylbenzene sulfonic acid is used, separate polydisperse parti...