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Regular version of the site
Of all publications in the section: 133
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Article
Safonov G., Palahí M., Pantsar M. et al. Solutions. 2020. Vol. 2. No. 11. P. 1-13.

In the last 50 years, the biosphere, upon which humanity depends, has been altered to an unparalleled degree. The current economic model relying on fossil resources and addicted to “growth at all costs” is putting at risk not only life on our planet, but also the world’s economy. The need to react to the unprecedented COVID-19 crisis is a unique opportunity to transition towards a sustainable wellbeing economy centered around people and nature. After all, deforestation, biodiversity loss and landscape fragmentation have been identified as key processes enabling direct transmission of zoonotic infectious diseases. Likewise, a changing climate has profound implications for human health. Putting forward a new economic model requires transformative policies, purposeful innovation, access to finance, risk-taking capacity as well as new and sustainable business models and markets. But above all we need to address the past failure of our economy to value nature, because our health and wellbeing fundamentally depends on it. A circular bioeconomy offers a conceptual framework for using renewable natural capital to holistically transform and manage our land, food, health and industrial systems with the goal of achieving sustainable wellbeing in harmony with nature. Within the framework of the Sustainable Markets Initiative, under the leadership of His Royal Highness The Prince of Wales, a 10-Point Action Plan to create a circular bioeconomy is proposed below. The Action Plan is a response to The Prince of Wales’ call to invest in nature as the true engine for our economy. The Action Plan, guided by new scientific insights and breakthrough technologies, is articulated around six transformative action points further discussed below and four enabling action points, which mutually reinforce each other.

Added: Jun 20, 2020
Article
Boldyrev K., Молчанова А., Простников М. et al. Physical Review B: Condensed Matter and Materials Physics. 2017. Vol. 96. No. 17. P. 174305-1-174305-11.

Copper borate Cu3(BO3)2 is a complex compound with a layered crystallographic structure in which the Jahn-Teller active and magnetic copper Cu2+ ions occupy 16 nonequivalent positions in the unit cell displaying controversial magnetic behavior. In this paper, we report on the infrared and Raman spectroscopic studies of the lattice dynamics and the electronic structure of 3d9 copper states below the fundamental absorption band. The lattice dynamics is characterized by a large number of phonons due to a low P1 space-group symmetry and a large unit cell with Z = 10. An unusually rich set of phonons was found in the low-energy part of the infrared and Raman spectra below 100 cm−1, which we tentatively assign to interlayer vibrations activated by a crystal superstructure and/or to weak force constants for modes related to some structural groups. Several phonons show anomalous behavior in the vicinity of the magnetic phase transition at TN = 10 K, thus evidencing magnetoelastic interaction. No new phonons were found below TN, which excludes the spin-Peierls type of the magnetic transition. In the region of electronic transitions, a strong broad absorption band centered at ∼1.8 eVis observed, which we assign to overlapping of transitions between the 3d9 states of Cu2+ ions split by the crystal field in nonequivalent positions. The fundamental charge-transfer absorption band edge has a complex structure and is positioned around ∼2.8−3.0 eV.

Added: Feb 8, 2019
Article
Ay A. N., Zumreoglu-Karan, B., Kalinichev A. G. et al. Journal of Porous Materials. 2020. Vol. 27. P. 735-743.

Magnetic nanocomposites involving tetraborate ion (TB)-intercalated Mg–Al-layered double hydroxide (LDH) shell supported on magnesium ferrite core particles are synthesized, characterized, and compared with their non-magnetic analogues. The compositions of the obtained nanocomposites were determined and structural investigations were made by powder X-ray diffraction and Fourier transform infrared spectroscopy. Particle characteristics were examined by size distribution, specific surface area measurements, scanning electron microscopy and transmission electron microscopy. Room-temperature magnetic measurements were performed with a vibrating sample magnetometer. The dynamics and structure of the interlayer water molecules and borate ions were studied by molecular dynamics simulations. Analytical and modeling studies verified that the TB ions were arranged between the LDH layers in oblique positions. The products were found to carry ca. 6% boron (10**17 B atom/μg nanocomposite). The magnetic nanocomposite showed superparamagnetic properties and can potentially find applications in biomedical fields for the site-specific delivery of bio-potent boron agents.

Added: Feb 26, 2020
Article
Boldyrev K., Молчанова А., Ерофеев А. et al. Journal of Physics: Conference Series. 2017. Vol. 917. No. 072003. P. 1-4.

The work presents a study of manganese-doped copper metaborate (Cu, Mn) B2O4 using optical spectroscopy. The temperature of the antiferromagnetic phase transition T-N = 19 K has been defined according to the absorption spectra. Polarization studies (Cu, Mn) B2O4 in isotropic ab-plane show the presence of linear antiferromagnetic dichroism in the magnetically ordered state previously observed in pure copper metaborate CuB2O4. This measurement allows to find the magnetic phase transition into an elliptical structure at the temperature T* = 7.0 K.

Added: Feb 8, 2019
Article
Nefedov V. N. Measurement Techniques. 2019. Vol. 62. No. 5. P. 449-454.

A method for the construction of microwave devices with longitudinal interaction is proposed. Devices of the present type create uniform cross-sectional distribution of temperature of rods made of polymer composite materials. Results from theoretical and experimental investigations of the cross-sectional distribution of the temperature of the material of the rod as well as the parameters of the microwave device are presented.

Added: Dec 2, 2019
Article
Volfkovich Y. M., Gryzlov D., Sosenkin V. et al. Electrochimica Acta. 2019. Vol. 319. P. 552-560.

Charge-discharge processes of supercapacitor with carbon black KJEC 600/Li in non-aqueous electrolyte: 1 M LiPF6 in a mixture of ethylene carbonate (1/3), diethyl carbonate (1/3), dimethyl carbonate (1/3) are investigated. Galvanostatic cycling was carried out in the range from 1 to 4 V with currents from 100 to 5000 mA/g of carbon black. The maximum discharge capacity of 196 F/g has been reached. The porous structure and hydrophilic-hydrophobic properties of carbon black KJEC 600 were investigated by the standard contact porosimetry method (MSCP). The following values were obtained: total specific surface area of 2500 m2/g, total porosity of 7.8 cm3/g, hydrophilic porosity of 4.9 cm3/g, hydrophobic porosity of 2.9 cm3/g. The obtained experimental dependence of the energy efficiency has a maximum (80%) at a current of 250 mA/g. Mathematical modeling of charge-discharge processes of the supercapacitor is developed with taking into account the charging of the double electric layer (EDL) and adsorption of lithium ions according to the Butler-Volmer equation and the Frumkin isotherm for the carbon electrode are taken into account. From the comparison of the calculated and measured charge-discharge curves it follows that these curves are satisfactorily consistent with each other, which indicates the correctness of the model. The density of the exchange current and the specific capacitance of the EDL refereed to the true surface found by the fitting are equal to i0,ad = 2.8 × 10−29A/сm2 and Cdl = 3.5 μF/сm2 respectively.

On the basis of the developed model for different specific currents the energy efficiency dependences on the exchange current density of the adsorption reaction were calculated. Interestingly, these dependencies have a minimum. Based on the model, the profiles of the potential the surface coverage of lithium ions were also calculated.

Added: Dec 5, 2019
Article
Bondarenko G.G., Fisher M. R., Kristya V. I. et al. Приборы и методы измерений. 2019. Vol. 10. No. 1. P. 7-13.

In this work, a model of the low-current discharge in the argon–mercury mixture at the existence of a thin insulating film on the cathode surface is developed. It takes into account, besides of the ion-electron emission from the cathode surface, the field electron emission from the cathode metal substrate into the film, caused by the strong electric field generated in it in the discharge.

Added: Mar 31, 2019
Article
Andreev D. V., Bondarenko G.G., Andreev V. V. et al. Journal of Physics: Conference Series. 2021. Vol. 1740.

We have modeled the charge effects in radiation MOS sensors functioning in a wide range of electric fields including high-field injection of electrons into the dielectric film. In order to study the charge effects taking place in MOS sensors, we use an extended model suggested by us previously. The extended model, besides the accumulation of positive charge in the dielectric and the generation of the surface states at the interface, takes into consideration the accumulation of negative charge in the bulk of dielectric film caused by the electron capturing on traps. We demonstrate that the accumulation of the negative and positive charges in the bulk of the gate dielectric under high fields can significantly influence on the redistribution of electric fields inside the dielectric and, as a sequence, on change of the charge state of MOS structure which describes the sensor characteristics.

Added: Jan 26, 2021
Article
Andreev D. V., Bondarenko G.G., Andreev V. V. et al. Acta Physica Polonica A . 2019. Vol. 36. No. 2. P. 263-266.

The paper considers an influence of different kinds of radio-frequency plasma treatments onto modification of MIS structures with a thermal SiO2 film which is aimed at improvement of electro-physical parameters of the film. It was found that for the modification of MIS structures it is more preferable to utilize the oxygen plasma radio-frequency plasma treatment performed by a setup with the parallel-plate-type reactor. This is due to the fact that setup allows to have lesser degradation of charge characteristics of the gate dielectric in comparison with a setup with the cylindrical quartz reactor. The radio-frequency plasma treatment stimulates restructuring of SiO2 film and, as a result, diminishes possibility of sample breakdown and raises injection and radiation stability of the samples.

Added: Nov 5, 2019
Article
Androniuk I., Kalinichev A. G. Applied Geochemistry. 2020. Vol. 113. P. 104496.

Due to their high durability and immobilization properties, cementitious materials have found a considerable application in the design and construction of radioactive waste repositories in the last decades. During cement paste production, organic additives are introduced to modify various properties of cement. The presence of such organic complexants may negatively affect the immobilizing properties of cement with respect to radionuclides. For better understanding and prediction of the effects of interactions between organic molecules and cementitious materials with radionuclides, we have developed several representative models consisting of three principal components: (i) calcium silicate hydrate (C-S-H) phase - the main binding phase of cement; (ii) gluconate, a simple well-described molecule, as a representative of organic additives; (iii) U(VI), as one of the most studied radionuclides of the actinide series. The C-S-H phase with low Ca/Si ratio (~0.83) typical for “low-pH” and degraded cement pastes has been selected for this modelling study. Structural, and energetic aspects of the sorption processes of uranyl, gluconate, and their mutual correlations on the surface of cement were quantitatively modeled by classical molecular dynamics (MD) and potential of mean force (PMF) calculations. The ternary surface complex formation between uranyl hydroxides and Ca2+ cations at the C-S-H aqueous interfaces is shown to have an important role in the overall sorption process. In the presence of gluconate, U(VI) sorption on C-S-H is facilitated by weakening the Ca2+ binding with the surface. Additionally, Na+ is proven to be an important competitor for certain surface sorption sites and can potentially affect the equilibrium properties of the interface.

Added: Feb 26, 2020
Article
Chichkov V., Shamrai A., IIl’ichev I. et al. Materials Letters. 2020. Vol. 260. P. 1-4.

We report a study of epitaxial superconductive NbN films on vicinal to the X-cut of single crystal LiNbO3 substrates grown using reactive magnetron sputtering of Nb target in Ar -N2 atmosphere. It is found that the NbN films reveal sharp superconductive transition at TC= 15.2 K and anisotropy of critical current. Critical current measured along the Z direction exceeds JC along the Y direction regardless of the orientation of step edges of the vicinal surfaces. The anisotropy effect is attributed to NbN film uniaxial stress due to the lattice mismatch of NbN (0 0 1) layer along the Z direction of LiNbO3.

Added: Dec 13, 2019
Article
Boldyrev K., Gutsenko D., Klimin S. et al. Optics and Spectroscopy. 2020. Vol. 128. No. 9. P. 1374-1378.

We have studied high-resolution low-temperature IR luminescence and absorption spectra of undoped high-quality SiC single crystals of the 4H and 6H hexagonal modifications. Narrow lines with a width of smaller than 0.2 cm–1 have been revealed, with some of which being observed for the first time. We have found that some of the lines in the 4H and 6H modifications have similar structures; however, the lines in SiC-4H are shifted to the high-energy part of the spectrum by ~180 cm–1. For the most intense quartet in the range of 1.3 μm, we have succeeded in constructing the energy structure of levels for both the 4H modification and the 6H modification based on their luminescence and absorption spectra.

Added: Oct 22, 2020
Article
Dmitrii Demin, Ivan Zakhariev, Taisia Labutina et al. Journal of Chemical Technology and Metallurgy. 2018. Vol. 53. No. 2. P. 380-385.

In this study the process of a hot laboratory rolling of a round bar on the flat rolls was studied by laboratory

experiments and numerical modelling in order to evaluate the effect of boundary conditions and simulation techniques

on the model predictions. The computer simulations of rolling process were performed by two different techniques

based on Finite Element Method (FEM). The first technique solves three dimensional problems. The second one is

based on the sequential solution of a series of generalized plane problems. Each technique was used for solving of

isothermal forming task and non-isothermal one. The results were compared with laboratory rolling performed with

different reductions and at different temperatures. It was found that the difference of initial temperature is incon-

sequential to the prediction of strain and strain-rate distributions. This observation was confirmed experimentally.

Added: Jul 3, 2018
Article
Zakhariev I. Y. Journal of Physics: Conference Series. 2021. Vol. 1740. P. 1-6.

Superplastic blow forming is a technology of shell parts production. The development of these processes requires computer simulation which cannot be realized without accurate parameters of the applied material. This characterization can be based on results of free bulging tests. Characterization techniques utilize the models of the dome growth during the bulging test. This study is devoted to the assessing of friction coefficient effect on the linear behavior of normalized thickness - normalized height relation.

Added: Jan 27, 2021
Article
Jarrar F., Sorgente D., Aksenov S. A. et al. Materials Science Forum. 2018. Vol. 941. P. 2343-2348.

Superplastic forming has already been proven as a practical solution for manufacturing lightweight components in niche applications such as the aerospace and luxury cars industries. The demand to produce such components will continue with the limited nature of the energy resources available today. Therefore, superplastic materials are expected to stay as potential candidates in such applications.  In addition, superplastic forming offers many unique advantages over conventional forming techniques including greater design flexibility, relatively low tooling cost, and no spring back. However, the full potential of the process has not yet been fulfilled due to concerns about the nonuniformity of the produced parts thickness profiles and the need for heating to achieve the superplastic properties of the material. In this paper the authors address the main challenges that hinder the wide spread of the process. It is of great practical importance, for example, to develop accurate simulations of the superplastic forming process. Such simulations are required for identifying the optimum process parameters for high quality components. The results of any such simulations or experimental investigations should be translated into simple and clear industrial guidelines. In addition, they discuss the current trends and the prospects of this process.

Added: Dec 26, 2019
Article
Rumyantsev B., Guk I., Kozachuk A. et al. Acta Astronautica. 2020. Vol. 176. P. 609-612.

The authors investigate aluminum shaped charge jet (SCJ) penetration into an aluminum alloy target at 8–11 km/s velocities. The analysis of kinetics, penetration parameters and structures of cavern surfaces formed after the penetration show that at velocities exceeding 9–11 km/s, the hydrodynamic character of the penetration changes due to the melting of the interacting materials. When during the penetration process SCJ velocity exceed 9 km/s, porous layer of aluminum nanospheres with 20–100 nm in diameter form in the penetration region. The results obtained are appropriate for developing spacecraft shield protections against most dangerous space fragments.

Added: Sep 19, 2020
Article
Pavlenko V. I., Bondarenko G.G., Cherkashina N. I. Inorganic Materials: Applied Research. 2020. Vol. 11. No. 2. P. 304-311.

The article presents the possibility of obtaining polymer composite materials based on thermoplastic polyimide and tungsten oxide (WO3) modified with a hydrophobic silicone fluid. Data on surface microscopy, Vickers microhardness, density, and thermal stability of composites with different tungsten oxide contents are presented. As a result of modifying tungsten oxide, its surface becomes hydrophobic, and the contact angle increases from 31° to 101°. The microstructure of the surface of composites has a fine-grained structure without microcracks and chips. The lowest density material has no filler. With increasing filler content, the density increases. When the content of the filler is 80 wt %, the density is 4.35 g/cm3. The optimum content of tungsten oxide filler is 60 wt % as measured by the surface microhardness. The work shows that the introduction of the proposed filler significantly increases the heat resistance of polyimide. Pure polyimide is stable up to 425°С, and at a temperature of 680°С, its full thermal decomposition takes place. With increasing content of modified tungsten oxide in the composite, the rate of mass loss decreases. In the composite containing 60 wt % filler at 680°C, the mass loss is 38%.

Added: Apr 2, 2020
Article
Kiselyova N., Dudarev V., Ryazanov V. et al. Inorganic Materials: Applied Research. 2021. Vol. 12. No. 2. P. 328-336.

New chalcospinels of the most common compositions were predicted: AIBIIICIVX4 (X = S or Se) and AIIBIIICIIIS4 (A, B, and C are various chemical elements). They are promising for the search for new materials for magneto-optical memory elements, sensors, and anodes in sodium-ion batteries. The parameter “a” values of their crystal lattice are estimated. When predicting, only the values of the properties of chemical elements were used. The calculations were carried out using machine learning programs that are part of the information-analytical system developed by the authors (various ensembles of algorithms of the binary decision trees, the linear machine, the search for logical regularities of classes, the support vector machine, Fisher linear discriminant, the k-nearest neighbors, the learning a multilayer perceptron, and a neural network) for predicting chalcospinels not yet obtained, as well as an extensive family of regression methods, presented in the scikit-learn package for the Python language, and multilevel machine learning methods that were proposed by the authors for estimation of the lattice parameter value of new chalcospinels. The prediction accuracy of new chalcospinels according to the results of the cross-validation is not lower than 80%, and the prediction accuracy of the parameter of their crystal lattice (according to the results of calculating the mean absolute error when cross-validation in the leave-one-out mode) is ±0.1 Å. The effectiveness of using multilevel machine learning methods to predict the physical properties of substances is shown.

Added: Apr 2, 2021
Article
Boldyrev K., Романов А., Хаула Е. et al. Journal of the American Ceramic Society. 2019. Vol. 102. No. 5. P. 2745-2751.

Single crystal of TlCl was doped with NIR photoluminescent univalent bismuth cations by prolonged immersion in liquid bismuth metal. The ion exchange Tl+ + Bi0 ↔ Tl0 + Bi+ at the crystal surface with subsequent Bi+ migration to the bulk are expected to drive the doping process. Contrary with Bi‐doped TlCl crystals, grown by Bridgman method, the ion exchange does not produce the additional nonluminescent bismuth‐containing centers. The investigation of photoluminescence emission and excitation spectra lead to the conclusion, that Bi+ is the main NIR emissive center in Bi‐doped TlCl.

Added: Feb 8, 2019
Article
Trainov K., Salikov R., Luponosov Y. et al. Mendeleev Communications. 2019. Vol. 29. No. 3. P. 304-306.

First representatives of a novel class of compounds containing an electron-accepting hydrazonocyclopentadiene moiety, π-conjugated phenylene spacer, and electron-donating triphenylamine moiety have been synthesized. Investigation of their optical, electrochemical and photovoltaic properties revealed a high potential of the hydrazonocyclopentadiene acceptor moiety in the design of donor-acceptor compounds for organic photovoltaics.

Added: Oct 14, 2020
Article
Яшкардин Р. В., Sorokin K. IEEE NW Russia Young Researchers in Electrical and Electronic Engineering Conference. 2016. P. 736-739.

a brief description of the principles of functioning of the device for producing an ultradispersive metal powders under the affection of powerful electrically charged energy streams is presented in the article. A method of creating a mathematical model of a device components for producing an ultrsadispersive particles is explained. A comparison of the results of numeric modeling of the processes to take place in the device to an experimental received data is showing the adequacy of the mathematical model. Basing the received data, the abrupt change of a plasma arc resistance while the device working is being demonstrated.

Added: Oct 15, 2021