H-index of the most cited co-author from among TPU scientists is 55. The IF of the most rated journal, were TPU scientists published their articles, makes 8.462 (StrAU Ecoenergy).
In October, fellows from the Department of Heat and Power Process Automation published 10 articles in the Q1 journal with IF?3.
The article by Prof. Sergey Gnyusov from the Department of Equipment and Technology of Welding, which was published in the Journal of Alloys and Compounds (IF 3.133; Q1) became the most popular in media. Its altimetry indicators exceed the output of other TPU publications.
Oleg Kabov, professor of the Department of Theoretical and Industrial Heat System Engineering.
Journal: Physical Review Letters (IF 8.462; Q1)
Levitating droplets of liquid condensate are known to organize themselves into ordered arrays over hot liquid-gas interfaces. We report experimental observation of similar behavior over a dry heated solid surface. Even though the lifetime of the array is shorter in this case, its geometric characteristics are remarkably similar to the case of droplets levitating over liquid-gas interfaces. A simple model is developed that predicts the mechanisms of both droplet levitation and interdroplet interaction leading to pattern formation over a dry surface; the model is shown to be in good agreement with the experimental data. Using the insights from the new experiments, we are able to resolve some long-standing controversies pertaining to the mechanism of levitation of droplets over liquid-gas interfaces.
Dmitrii Glushkov, associate professor of the Department of Heat and Power Process Automation, Pavel Strizhak, head of the Department of Heat and Power Process Automation.
Journal: Journal of Cleaner Production (IF 5.715; Q1)
To expand the resource base of fuels and methods of hydrocarbon waste recovery, this paper presents the study of the ignition features and conditions of composite fuel slurries based on wastes from coal, chemical, petrochemical, energy, and transport industries. Composite liquid fuels have been prepared using basic components: filter cakes of low-caking, nonbaking, and bituminous coal; engine, turbine, and transformer oil waste; plasticizer. According to a well-known experimental approach, the investigations of the ignition processes have been performed for single fuel droplets (with a radius ranging from 0.5 mm to 1.5 mm) covering a fast-response thermocouple junction.
Finally, the minimum temperatures were specified sufficient for the sustainable ignition of composite liquid fuel. The established ranges of minimum temperatures show the possibility of burning fuel slurries based on coal and oil processing wastes in heat and power boilers of different capacity. The temperature modes can be adjusted to the required environmental, economic and energy performance indicators. The maximum temperature of a droplet during the combustion process is more than 1100 K. This result confirms the high combustion heat of fuel slurries, even those based on typical industrial wastes, and shows great prospects of their application in the thermal power engineering. The wide use of abundant industrial wastes as the main fuel components of coal water slurries containing petrochemicals is a high-potential solution to the global problem of their recovery and the reduction of the environmental load of coal-based thermal power engineering on the nature and humankind.
Geniy Kuznetsov, head of the Department of Theoretical and Heat Systems Engineering, Maxim Piskunov, assistant at the Department of Heat and Power Process Automation, Pavel Strizhak, head of the Department of Heat and Power Process Automation.
Journal: International Journal of Thermal Sciences (IF 3.615; Q1)
The study reports results of the experimental research on the explosive breakup of heterogeneous water drops in high-temperature (800–1200 K) conditions typical for fires. The temperature of heating conforms to mean values for large forest fires. We use water drops containing special-purpose inclusions, such as 1–3 mm solid opaque particles (natural graphite). Laboratory experiments enable us to define conditions for the intensive fragmentation of such the drops. This process is characterized by formation of droplets of smaller size. The number of fragments can be from several ones to several hundreds. As a result, the evaporation surface area of liquid increases 3–15-fold during such the fragmentation. This effect is important for the most complete water evaporation in a flame during the fire extinguishing process. In such a case, the maximum temperature reduction in a flame zone becomes possible by absorption of heat of phase change. Field tests show that the usage of suspensions based on water facilitates a dramatic drop in temperature in a flame zone by 40–70 K as compared to water without additives. Consequently, fire extinguishing occurs during shorter time and by using smaller volume of water. Both the characteristics can decrease by 30–40% as compared to water without additives.
Sergey Misyura, senior research fellow of the Department of Heat and Power Process Automation.
Journal: International Journal of Thermal Sciences (IF 3.615; Q1)
Experimental data on nonisothermal evaporation of sessile droplets of water-salt solutions (LiBr + H2O; CaCl2+H2O) were obtained. Evaporation of droplets of volatile liquids occurs with almost constant evaporation rate, and the problem is solved in a stationary approximation. High-temperature evaporation of water-salt solutions leads to significant difficulties at modeling the heat and mass transfer. In this case, the evaporation rate substantially decreases with time. With the growth of salt concentration in the solution from 11% to 60%, the partial pressure of water vapor at the interface falls by an order of magnitude. In this work, we have performed simulation, considering diffusion in solutions, a non-isothermal character, and the Stefan flow, and proposed a simple method for calculating the mass flow. The resulting technique can qualitatively and quantitatively predict the solution behavior with a significant change in the external boundary conditions in time.
Olga Vysokomornaya, senior engineer of the Department of Heat and Power Process Automation, Maxim Piskunov, assistant of the Department of Heat and Power Process Automation, Pavel Strizhak, head of the Department of Heat and Power Process Automation.
Journal: Applied Thermal Engineering (IF 3.444; Q1)
The enhancement of the evaporation rate of a heterogeneous water drop is experimentally investigated. A water drop encapsulating a solid graphite inclusion is instantaneously placed in the very hot air. Under action of the high ambient temperature and due to different thermal properties between water and solid inclusion, the initial drop explodes and creates numerous very small droplets. The vaporization rate of the water drop is strongly increased leading to a short time life of the drop. High speed video recording is used to detail the explosive breakup mechanism of a drop immersed in hot air when its temperature varies in the range between 1073 K and 1373 K. The target of the study is to determine the possible conditions for the increase of the water/air surface of the drop after breakup, i.e., the ratio of the final to initial surface, Sout/Sin, and to verify that this enlargement is responsible of the evaporation rate enhancement. For this purpose, we investigate drops of different initial volumes (5–15 µl) with graphite solid inclusions of different shapes and volumes: 2 × 2 × 1 mm, 2 × 2 × 2 mm, or 2 × 2 × 3 mm. The water surface ratio Sout/Sin is given as function of Vw/Vinc, which is the ratio of initial volume of water drop Vw to the volume of solid graphite inclusion Vinc. The study has shown that the maximum value of the ratio Sout/Sin ≈ 15 can be reached when Vw ∼ Vinc. When, the ratio of Sout/Sin varies in the range 1 to 15. The increase of the evaporating surface is of the highest interest to improve the heat transport and to be used and developed in heat technologies.
Unconventional Natural Resources
Alexander Charkin, junior research fellow of the Arctic Sea’s Carbon Research International Laboratory, Natalia Shakhova, senior research fellow of the Arctic Sea’s Carbon Research International Laboratory, Gustafsson O. (h-index: 55), Oleg Dudarev, research fellow of the Arctic Sea’s Carbon Research International Laboratory, Maxim Cherepnev, engineer of the Radiation Safety Office, Alexey Ruban, assistant of the Department of Geology and Minerals Prospecting, Igor Semiletov, professor of the Department of Geology and Minerals Prospecting.
Journal: Cryosphere (IF 4.803; Q1)
It has been suggested that increasing terrestrial water discharge to the Arctic Ocean may partly occur as submarine groundwater discharge (SGD), yet there are no direct observations of this phenomenon in the Arctic shelf seas. This study tests the hypothesis that SGD does exist in the Siberian Arctic Shelf seas, but its dynamics may be largely controlled by complicated geocryological conditions such as permafrost. The field-observational approach in the southeastern Laptev Sea used a combination of hydrological (temperature, salinity), geological (bottom sediment drilling, geoelectric surveys), and geochemical (224Ra, 223Ra, 228Ra, and 226Ra) techniques. Active SGD was documented in the vicinity of the Lena River delta with two different operational modes. In the first system, groundwater discharges through tectonogenic permafrost talik zones was registered in both winter and summer. The second SGD mechanism was cryogenic squeezing out of brine and water-soluble salts detected on the periphery of ice hummocks in the winter. The proposed mechanisms of groundwater transport and discharge in the Arctic land-shelf system is elaborated. Through salinity vs. 224Ra and 224Ra / 223Ra diagrams, the three main SGD-influenced water masses were identified and their end-member composition was constrained. Based on simple mass-balance box models, discharge rates at sites in the submarine permafrost talik zone were 1.7 × 106?m3?d−1 or 19.9?m3?s−1, which is much higher than the April discharge of the Yana River. Further studies should apply these techniques on a broader scale with the objective of elucidating the relative importance of the SGD transport vector relative to surface freshwater discharge for both water balance and aquatic components such as dissolved organic carbon, carbon dioxide, methane, and nutrients.
Humborg c. (h-index: 34), Anderson L. (h-index: 34), Bjork G. (h-index: 23), Morth C. M. (h-index: 29), Gustafsson B.G. (h-index: 27), Igor Semiletov, professor of the Department of Geology and Minerals Prospecting, et al.
Journal: Global Biogeochemical Cycles (IF 4.655; Q1)
This large-scale quasi-synoptic study gives a comprehensive picture of sea-air CO2 fluxes during the melt season in the central and outer Laptev Sea (LS) and East Siberian Sea (ESS). During a 7 week cruise we compiled a continuous record of both surface water and air CO2 concentrations, in total 76,892 measurements. Overall, the central and outer parts of the ESAS constituted a sink for CO2, and we estimate a median uptake of 9.4 g C m−2 yr−1 or 6.6 Tg C yr−1. Our results suggest that while the ESS and shelf break waters adjacent to the LS and ESS are net autotrophic systems, the LS is a net heterotrophic system. CO2 sea-air fluxes for the LS were 4.7 g C m−2 yr−1, and for the ESS we estimate an uptake of 7.2 g C m−2 yr−1. Isotopic composition of dissolved inorganic carbon (δ13CDIC and δ13CCO2) in the water column indicates that the LS is depleted in δ13CDICcompared to the Arctic Ocean (ArcO) and ESS with an offset of 0.5‰ which can be explained by mixing of δ13CDIC-depleted riverine waters and 4.0 Tg yr−1 respiration of OCter; only a minor part (0.72 Tg yr−1) of this respired OCter is exchanged with the atmosphere. Property-mixing diagrams of total organic carbon and isotope ratio (δ13CSPE-DOC) versus dissolved organic carbon (DOC) concentration diagram indicate conservative and nonconservative mixing in the LS and ESS, respectively. We suggest land-derived particulate organic carbon from coastal erosion as an additional significant source for the depleted δ13CDIC.
Space Materials Science
Rashid Valiev, assistant of the Department of Chemistry and Chemical Technology, Sundholm D. (h-index: 11) et al.
Journal: Physical Chemistry Chemical Physics (IF 4.123; Q1)
Magnetic and spectroscopic properties of a number of formally antiaromatic carbaporphyrins, carbathiaporphyrins and isophlorins with 4n π electrons have been investigated at density functional theory and ab initio levels of theory. The calculations show that the paratropic contribution to the magnetically induced ring-current strength susceptibility and the magnetic dipole-transition moment between the ground and the lowest excited state are related. The vertical excitation energy (VEE) of the first excited state decreases with increasing ring-current strength susceptibility, whereas the VEE of the studied higher-lying excited states are almost independent of the size of the ring-current strength susceptibility. Strong antiaromatic porphyrinoids, based on the magnitude of the paratropic ring-current strength susceptibility, have small energy gaps between the highest occupied and lowest unoccupied molecular orbitals and a small VEE of the first excited state. The calculations show that only the lowest S0 → S1 transition contributes signficantly to the magnetically induced ring-current strength susceptibility of the antiaromatic porphyrinoids. The decreasing optical gap combined with a large angular momentum contribution to the magnetic transition moment from the first excited state explains why molecules III–VII are antiaromatic with very strong paratropic ring-current strength susceptibilities. The S0 → S1 transition is a magnetic dipole-allowed electronic transition that is typical for antiaromatic porphyrinoids with 4n π electrons.
Nuclear Technologies for Oncology
Roman Surmenev, associate professor of the Department of Experimental Physics, Maria Surmeneva, senior research fellow of the Laboratory of Plasmonic Hybrid Systems, Irina Grubova, engineer of the Laboratory of Plasmonic Hybrid Systems, Roman Chernozem, engineer of the Laboratory of Plasmonic Hybrid Systems, Baumbach T. (h-index:31), Epple M. (h-index: 48) et al.
Journal: Applied Surface Science (IF 3.387; Q1)
A pure hydroxyapatite (HA) target was used to prepare the biocompatible coating of HA on the surface of a polytetrafluorethylene (PTFE) substrate, which was placed on the same substrate holder with technically pure titanium (Ti) in the single deposition runs by radio-frequency (RF) magnetron sputtering. The XPS, XRD and FTIR analyses of the obtained surfaces showed that for all substrates, instead of the HA coating deposition, the coating of a mixture of calcium carbonate and calcium fluoride was grown. According to SEM investigations, the surface of PTFE was etched, and the surface topography of uncoated Ti was preserved after the depositions. The FTIR results reveal no phosphate bonds; only calcium tracks were observed in the EDX-spectra on the surface of the coated PTFE substrates. Phosphate oxide (V), which originated from the target, could be removed using a vacuum pump system, or no phosphate-containing bonds could be formed on the substrate surface because of the severe substrate bombardment process, which prevented the HA coating deposition. The observed results may be connected with the surface re-sputtering effect of the growing film by high-energy negatively charged ions (most probably oxygen or fluorine), which are accelerated in the cathode dark sheath.
Tatiana Fursa, senior research fellow of the Research Laboratory of Electronics, Dielectrics and Semiconductors, Denis Dann, research fellow of the Research Laboratory of Electronics, Dielectrics and Semiconductors, Maxim Petrov, junior research fellow of the Research Laboratory of Electronics, Dielectrics and Semiconductors.
Journal: Construction and Building Materials (IF 3.169; Q1)
The article examines damage caused to steel and fiberglass reinforcement concrete by freeze-thaw cycles in saline medium conditions. After 12 freeze-thawing cycles, the concrete-rebar bond strength decreases by 30% for steel and by 40% for fiberglass. A method of evaluating the concrete-rebar bond strength is proposed. The evaluation procedure is based on measuring electric response to mechanical impact. Energy attenuation coefficient and the signals' spectrum centroid could be used as the diagnostic criteria for the evaluation of concrete-rebar bond strength. After 12 FT cycles the electric signal's energy attenuation coefficient increases by about 40–45%, and the maximum signals' spectrum centroid increasing reaches about 8 kHz. The proposed method can be used to monitor the evolution of concrete-rebar bond strength in complex climate testing conditions.
Sergey Gnyusov, professor of the Department of Welding Engineering, Rostov V.V. (h-index: 26) et al.
Journal: Journal of Alloys and Compounds (IF 3.133; Q1)
We present the results of a comparative study of the shock-wave hardening regularities and mechanisms revealed for bulk (thickness h = 6 and 9.3 mm) targets made of austenitic 304L stainless steel and Hadfield steel. A high-current relativistic electron beam (45 ns, 1.35 MeV, 34 GW/cm2) produced by the SINUS-7 accelerator was used for generation of a shock wave. It is revealed by 2D-computer simulation for type 304 steel that the direct ablation of the target material leads to generation of shock wave with duration of ∼0.1 μs and amplitude of ∼20 GPa, and the strain rate during its direct propagation and reflection from the free rear surface decreases from ∼2 down to ∼0.4 μs−1. It is found experimentally that in the absence of a rear spall (h = 9.3 mm) the shock-wave loading of both steels leads to formation of three hardened layers: a front layer with a maximum microhardness at a depth of 0.5–1 mm from the bottom of ablation hole, which is in a reasonable agreement with the predictions of the heat-transfer calculations, as well as intermediate and rear-side layers. In case of 304L stainless steel, the depth distributions of microhardness and fraction of twinned grains are consistent with each other, while in the Hadfield steel, the correlation is within the front and intermediate hardened layers only. It is shown by microstructural characterization and analysis of hardening mechanisms that in the case of 304L stainless steel, both front and rear-side hardening are significantly associated with the formation of new intra-phase boundaries by deformation twinning. In the Hadfield steel, unlike the 304L stainless steel, the unusual rear-side hardening is mainly due to increasing the dislocation density under submicrosecond single cycle of compression followed by tension with peak stress of ∼3 GPa.