Tuning of the Interparticle interactions in ultrafine ferrihydrite nanoparticles

Knyazev, Yuriy V.,Balaev, Dmitry A.,Yaroslavtsev, Roman N.,Krasikov, Aleksandr A.,Velikanov, Dmitry A.,Mikhlin, Yuriy L.,Volochaev, Mikhail N.,Bayukov, Oleg A.,Stolyar, Sergei V.,Iskhakov, Rauf S. Techno-Press 2022 Advances in nano research Vol.12 No.6

We prepared two samples of ultrafine ferrihydrite (FH) nanoparticle ensembles of quite a different origin. First is the biosynthesized sample (as a product of the vital activity of bacteria Klebsiella oxytoca (hereinafter marked as FH-bact) with a natural organic coating and negligible magnetic interparticle interactions. And the second one is the chemically synthesized ferrihydrite (hereinafter FH-chem) without any coating and high level of the interparticle interactions. The interparticle magnetic interactions have been tuned by modifying the nanoparticle surface in both samples. The coating of the FH-bact sample has been partially removed by annealing at 150℃ for 24 h (hereinafter FH-annealed). The FH-chem sample, vice versa, has been coated (1.0 g) with biocompatible polysaccharide (arabinogalactan) in an ultrasonic bath for 10 min (hereinafter FH-coated). The changes in the surface properties of nanoparticles have been controlled by XPS. According to the electron microscopy data, the modification of the nanoparticle surface does not drastically change the particle shape and size. A change in the average nanoparticle size in sample FH-annealed to 3.3 nm relative to the value in the other samples (2.6 nm) has only been observed. The estimated particle coating thickness is about 0.2-0.3 nm for samples FH-bact and FH-coated and 0.1 nm for sample FH-annealed. Mössbauer and magnetization measurements are definitely shown that the drastic change in the blocking temperature is caused by the interparticle interactions. The experimental temperature dependences of the hyperfine field <H_hf>(T) for samples FH-bact and FH-coated have not revealed the effect of interparticle interactions. Otherwise, the interparticle interaction energy E_int estimated from the <H_hf>(T) for samples FH-chem and FH-annealed has been found to be 121k_B and 259k_B, respectively.

On the discovery and study of anthraxolite in Triassic plagiorhyolite on the border of the Ural and western Siberia

Yuriy V. Erokhin,Kirill S. Ivanov 한국지질과학협의회 2019 Geosciences Journal Vol.23 No.2

This paper describes the discovery of the first solid bitumen in the plagiorhyolites of Sinara River (Kataysky District, Kurgan Oblast), which are part of the Early Triassic Turin volcanic-sedimentary series on the border of the Ural and Western Siberia. According to data provided by complex analytical studies, they were classified as low anthraxolites. It was found that the formation of solid bitumen in acidic volcanic rocks of Sinara River occurred during the late stage of establishment of the plagiorhyolite body during the formation of chalcedonic (agate) amygdales and secretions. Solidification and sedimentation of anthraxolite from hydrothermal solutions apparently took place under a radical prevalence of the carbonate ion, i.e., in the amygdales during the crystallization of calcite, while in the edge zones of brecciation of plagiorhyolite – of another carbonate, siderite. The source of the substance for the formation of anthraxolite in plagiorhyolites of Sinara River could be both the enclosing sedimentary rocks and deep (mantle) carbohydrate fluids.

High-temperature oxidation of europium (II) sulfide

Yuriy G. Denisenko,Maxim S. Molokeev,Alexander S. Krylov,Aleksandr S. Aleksandrovsky,Aleksandr S. Oreshonkov,Victor V. Atuchin,Nikita O. Azarapin,Pavel E. Plyusnin,Elena I. Sal’nikova,Oleg V. Andreev 한국공업화학회 2019 Journal of Industrial and Engineering Chemistry Vol.79 No.-

The process of high-temperature oxidation of EuS in the air was explored in the temperature range of500–1000 C. The oxidation reaction enthalpy was determined (DH0exp =1718.5 kJ/mol). The study ofoxidation products allowed to establish the mechanism of EuS oxidation with oxygen. At 500–600 C, EuSis oxidized to a mixture of Eu3+-containing compounds (Eu3S4, Eu2O2S). In the range of 700–1000 C, onlyeuropium oxysulfate Eu2O2SO4 is formed. The structure refinement for Eu2O2SO4 was performed by theRietveld method. The luminescence intensity of europium oxysulfate Eu2O2SO4 with characteristic 4f-4ftransitions from the 5D0 state was investigated as a function of oxidation temperature.

The role of acidification of the medium on the erythrocyte agglutinating and adsorbing properties of blood group-specific monoclonal antibodies

Yuriy Pavlovich Delevsky,Olexandr Anatoliyovich Zinchenko 대한이식학회 2023 Korean Journal of Transplantation Vol.37 No.3

Background: S tudies on the specificity of ABH antigen-antibody interactions at different pH values are rare. Therefore, the aim of this study was to estimate the effect of acidification of the reacting medium on the agglutinating ability of anti-A monoclonal antibodies (mABs) and their inhibition by glycoconjugates of red blood cell membranes. Methods: Anti-A mABs were obtained from the Fourth International Workshop on Monoclonal Antibodies Against Human Red Blood Cell and Related Antigens (on July 19-20, 2002, in Paris, France). The glycoconjugates were isolated from erythrocytes' membranes. The inhibition of the lipid and protein isotypes of the blood group A antigen was assessed. Results: The acidic medium decreased the agglutinating ability of acid immunoglobulin M (IgM) anti-A mABs, in contrast to alkaline immunoglobulin G (IgG) mABs. Meanwhile, at pH 6.5, IgM antibodies exhibited a high adsorption capacity, while IgG antibodies demonstrated a strong adsorption capacity at an alkaline pH. mABs 2-19, 2-28, 2-22, and 2-8 were inhibited by the acidic lipid and protein glycotopes of erythrocyte membranes. However, mAB 2-8 was inhibited by both acidic and alkaline glycotope variants. Conclusions: The agglutinating and adsorbing abilities of mABs, which are revealed at opposing pH values, should be taken into account during studies of antigen-antibody interactions.

An Empirical Study on the Success Factors for e-Business Development in Russian Enterprises

Yuriy Kim,Ho Kyun Shin 한국로고스경영학회 2012 로고스경영연구 Vol.10 No.3

Design and Hardware Implementation of Fractal Comb-Structured Signals

Yuriy Bobalo,Andriy Veryha,Mykhailo Klymash,Bohdan Mandziy,Ruslan Politanskyi 한국산학기술학회 2014 SmartCR Vol.4 No.6

Currently, wireless communications networks are developing very quickly and are utilizing more spectral resources. Despite all the efforts to improve wireless network performance and energy-efficiency, spectrum is still overloaded. This problem results in decreasing signal strength and increasing influence of interference. Therefore, it is highly important to develop new methods of data transmission in wireless networks, providing better energy- and spectral-efficiency. In this paper, we propose new types of fractional comb-structured signals. We developed signal models for different types of fractional signals. We also developed hardware for fractional signal generation and transmission based on the PIC16F873 microcontroller. Finally, we conducted experimental analysis of the obtained signals via oscilloscope. Results show that the proposed signal model can be implemented in wideband wireless communications networks, providing good characteristics.

Ukraine's revolution of dignity: The dynamics of Euromaidan

Yuriy Shveda,Joung Ho Park 한양대학교 아태지역연구센터 2016 Journal of Eurasian Studies Vol.7 No.1

This paper analyzes the civil revolution in Ukraine, which is also known as the Euromaidan Revolution. It is regarded as the Revolution of Dignity by Ukrainian citizens. In this respect, this paper focuses on a clarification of the dynamics of the Ukrainian civil revolution. The authors will try to trace the essential causes, processes, and historical implications of the Euromaidan Revolution. In addition, we plan to assess the nature of civil revolution. This study not only was based on the primary sources in Ukrainian language but also was described from the perspective of the participants of the revolution.

Moment of Inertia of Gas as a Source of Added Gravitational Field in Galaxies

Yuriy A. Portnov 한국우주과학회 2022 Journal of Astronomy and Space Sciences Vol.39 No.2

In this paper we propose a new perspective for explaining galaxy rotation curves. We conjecture that there is a gravitational moment of inertia which, together with gravitational mass, contributes to the gravitational potential. We substantiate a formula for the potential created by the moment of inertia. We validate our model by computing orbital rotation velocities for several galaxies and showing that computed rotation velocities correspond to the observed ones. Our proposed approach is capable of accounting for constant gas velocities outside of a galactic disc without relying on the dark matter hypothesis. Furthermore, it addresses several problems faced by the application of the dark matter hypothesis, e.g., the absence of inward collapse of dark matter into a galaxy, the spherical distribution of dark matter around galaxies, and absence of traces of the effect of dark matter in two ultra-diffuse galaxies, NGC 1052-DF2, and NGC 1052-DF4.

State filling dependent luminescence in hybrid tunnel coupled dot-well structures.

Mazur, Yuriy I,Dorogan, Vitaliy G,Ware, Morgan E,Marega, Euclydes,Benamara, Mourad,Zhuchenko, Zoryana Ya,Tarasov, Georgiy G,Lienau, Christoph,Salamo, Gregory J RSC Pub 2012 Nanoscale Vol.4 No.23

<P>A strong dependence of quantum dot (QD)-quantum well (QW) tunnel coupling on the energy band alignment is established in hybrid InAs/GaAs-In(x)Ga(1-x)As/GaAs dot-well structures by changing the QW composition to shift the QW energy through the QD wetting layer (WL) energy. Due to this coupling a rapid carrier transfer from the QW to the QD excited states takes place. As a result, the QW photoluminescence (PL) completely quenches at low excitation intensities. The threshold intensities for the appearance of the QW PL strongly depend on the relative position of the QW excitonic energy with respect to the WL ground state and the QD ground state energies. These intensities decrease by orders of magnitude as the energy of the QW increases to approach that of the WL due to the increased efficiency for carrier tunneling into the WL states as compared to the less dense QD states below the QW energy.</P>

On the Influence of the Moment of Inertia of Gas on the Galactic Rotation Curves

Portnov, Yuriy A. The Korean Space Science Society 2022 Journal of Astronomy and Space Sciences Vol.39 No.3

There are two models that explain the rotation curves of galaxies: dark matter, which gives the missing contribution to the gravitational potential of the standard theory of gravity, and modified theories of gravity, according to which the gravitational potential is created by ordinary visible mass. Both models have some disadvantages. The article offers a new look at the problem of galactic rotation curves. The author suggests that the moment of inertia creates an additional gravitational potential along with the mass. The numerical simulation carried out on the example of fourteen galaxies confirms the validity of such an assumption. This approach makes it possible to explain the constancy of gas velocities outside the galactic disk without involving the hypothesis of the existence of dark matter. At the same time, the proposed approach lacks the disadvantages of modified theories of gravity, where the gravitational potential is created only by the mass of visible matter.