High-speed solar-blind short wavelength ultraviolet radiation detectors based onκ(ε)-Ga_(2)O_(3)layers with Pt contacts were demonstrated and their properties were studied in detail.Theκ(ε)-Ga_(2)O_(3)layers were ...High-speed solar-blind short wavelength ultraviolet radiation detectors based onκ(ε)-Ga_(2)O_(3)layers with Pt contacts were demonstrated and their properties were studied in detail.Theκ(ε)-Ga_(2)O_(3)layers were deposited by the halide vapor phase epitaxy on patterned GaN templates with sapphire substrates.The spectral dependencies of the photoelectric properties of struc-tures were analyzed in the wavelength interval 200-370 nm.The maximum photo to dark current ratio,responsivity,detectiv-ity and external quantum efficiency of structures were determined as:180.86 arb.un.,3.57 A/W,1.78×10^(12) Hz^(0.5)∙cm·W^(-1) and 2193.6%,respectively,at a wavelength of 200 nm and an applied voltage of 1 V.The enhancement of the photoresponse was caused by the decrease in the Schottky barrier at the Pt/κ(ε)-Ga_(2)O_(3)interface under ultraviolet exposure.The detectors demon-strated could functionalize in self-powered mode due to built-in electric field at the Pt/κ(ε)-Ga_(2)O_(3)interface.The responsivity and external quantum efficiency of the structures at a wavelength of 254 nm and zero applied voltage were 0.9 mA/W and 0.46%,respectively.The rise and decay times in self-powered mode did not exceed 100 ms.展开更多
The development of a nanosecond discharge in a pin-to-pin gap filled with air at atmospheric pressure has been studied with high temporal and spatial resolutions from a breakdown start to the spark decay.Positive and ...The development of a nanosecond discharge in a pin-to-pin gap filled with air at atmospheric pressure has been studied with high temporal and spatial resolutions from a breakdown start to the spark decay.Positive and negative nanosecond voltage pulses with an amplitude of tens of kilovolts were applied.Time-resolved images of the discharge development were taken with a fourchannel Intensified Charge Coupled Device(ICCD)camera.The minimum delay between the camera channels could be as short as≈0.1 ns.This made it possible to study the gap breakdown process with subnanosecond resolution.It was observed that a wide-diameter streamer develops from the high-voltage pointed electrode.The ionization processes near the grounded pin electrode started when the streamer crossed half of the gap.After bridging the gap by the streamer,a diffuse discharge was formed.The development of spark leaders from bright spots on the surface of the pointed electrodes was observed at the next stage.It was found that the rate of development of the spark leader is an order of magnitude lower than that of the wide-diameter streamer.Long thin luminous tracks were observed against the background of a discharge plasma glow.It has been established that the tracks are adjacent to brightly glowing spots on the electrodes and are associated with the flight of small particles.展开更多
Location awareness in wireless networks is essential for emergency services,navigation,gaming,and many other applications.This article presents a method for source localization based on measuring the amplitude-phase d...Location awareness in wireless networks is essential for emergency services,navigation,gaming,and many other applications.This article presents a method for source localization based on measuring the amplitude-phase distribution of the field at the base station.The existing scatterers in the target area create unique scattered field interference at each source location.The unique field interference at each source location results in a unique field signature at the base station which is used for source localization.In the proposed method,the target area is divided into a grid with a step of less than half the wavelength.Each grid node is characterized by its field signature at the base station.Field signatures corresponding to all nodes are normalized and stored in the base station as fingerprints for source localization.The normalization of the field signatures avoids the need for time synchronization between the base station and the source.When a source transmits signals,the generated field signature at the base station is normalized and then correlated with the stored fingerprints.The maximum correlation value is given by the node to which the source is the closest.Numerical simulations and results of experiments on ultrasonic waves in the air show that the ultrasonic source is correctly localized using broadband field signatures with one base station and without time synchronization.The proposed method is potentially applicable for indoor localization and navigation of mobile robots.展开更多
In mmWave massive multiple-input multiple-output(MIMO)communication systems,the extension of low-complexity narrowband precoding schemes to be operated on wideband systems under frequency-selective channels remains an...In mmWave massive multiple-input multiple-output(MIMO)communication systems,the extension of low-complexity narrowband precoding schemes to be operated on wideband systems under frequency-selective channels remains an important challenge at the current time.This paper investigates a low complexity wideband hybrid precoding scheme for mmWave massive MIMO multicarrier systems under a single-user,fully-connected hybrid architecture.We show that the radio frequency(RF)precoding/combining vectors can be directly derived from the eigenvectors of the optimal fully-digital covariance matrix over all subcarriers in order to maximize the sum rate of spectral efficiency.We also suggest a new method that iteratively reduces the residual error between the covariance matrix and the sum of products of precoding matrices over all the subcarriers to improve the performance in the case where the number of RF chains is higher than the number of streams.The results of the simulation show that the proposed schemes’complexity is low compared to the present methods,and their performance can almost reach the upper bound achieved by the optimal full-baseband design.展开更多
The study focused on the modification with platinum of dark defective titania obtained via pulsed laser ablation. Both the method of Pt introduction and the nature of the Pt precursor were varied. All samples exhibite...The study focused on the modification with platinum of dark defective titania obtained via pulsed laser ablation. Both the method of Pt introduction and the nature of the Pt precursor were varied. All samples exhibited similar phase compositions, specific surface areas, and Pt contents. High-resolution transmission electron microscopy coupled with pulsed CO adsorption revealed increased dispersity when photoreduction and the hydroxonitrate complex (Me _(4) N) _(2) [Pt _(2) (OH) _(2) (NO _(3) ) _(8) ] were used. The sample featured a high content of single-atom species and subnano-sized Pt clusters. The X-ray photoelectron spectroscopy results showed that the photoreduction method facilitated the appearance of a larger number of Pt ^(2+) states, which appeared owing to the strong metal-support interaction (SMSI) eff ect of the transfer of electron density from the electron-saturated defects on the TiO _(2) surface to Pt ^(4+) . In the hydrogen evolution reaction, samples with a significant fraction of the Pt ^(2+) ionic component, capable of generating short-lived Pt^(0) single-atom sites under irradiation due to the SMSI eff ect, exhibited the highest photocatalytic activity. The 0.5Pt(C)/TiO_(2) -Ph sample exhibited the highest hydrogen yield with a quantum efficiency of 0.53, retaining its activity even after 8 h of operation.展开更多
This study investigates the glacial lake outburst flood(GLOF)hazards in the Tsambagarav mountain range in Western Mongolia,focusing on the Khukhnuruu Valley and its interconnected proglacial lakes.Over the last 30 yea...This study investigates the glacial lake outburst flood(GLOF)hazards in the Tsambagarav mountain range in Western Mongolia,focusing on the Khukhnuruu Valley and its interconnected proglacial lakes.Over the last 30 years,significant glacier retreats,driven by rising temperatures and changing precipitation patterns,have led to the formation and expansion of several proglacial lakes.Fieldwork combined with satellite data and meteorological analysis was used to assess the dynamics of glacier and lake area changes,with particular focus on the flood events of July 2021.The research reveals a substantial reduction in glacier area,particularly in the Khukhnuruu E complex,where glacier area decreased by 19.3%.The study highlights the influence of increasing temperatures and summer precipitation,which have accelerated ice melt,contributing to the expansion and eventual breaching of lakes.Additionally,lake area changes were influenced by the steepness of the terrain,with steeper slopes exacerbating peak discharge during floods.Of the studied seven lakes(Lake 1 to Lake 7),Lake 1 experienced the most dramatic reduction,with a decrease in area by 73.51%and volume by 84.84%,followed by Lake 7.This study underscores the region's vulnerability to climate-induced hazards and stresses the need for a comprehensive early warning system and disaster preparedness measures to mitigate future risks.展开更多
Detectors were developed for detecting irradiation in the short-wavelength ultraviolet(UVC)interval using high-quality single-crystallineα-Ga_(2)O_(3) films with Pt interdigital contacts.The films ofα-Ga_(2)O_(3) we...Detectors were developed for detecting irradiation in the short-wavelength ultraviolet(UVC)interval using high-quality single-crystallineα-Ga_(2)O_(3) films with Pt interdigital contacts.The films ofα-Ga_(2)O_(3) were grown on planar sapphire substrates with c-plane orientation using halide vapor phase epitaxy.The spectral dependencies of the photo to dark current ratio,responsivity,external quantum efficiency and detectivity of the structures were investigated in the wavelength interval of 200−370 nm.The maximum of photo to dark current ratio,responsivity,external quantum efficiency,and detectivity of the structures were 1.16×10^(4) arb.un.,30.6 A/W,1.65×10^(4)%,and 6.95×10^(15) Hz^(0.5)·cm/W at a wavelength of 230 nm and an applied voltage of 1 V.The high values of photoelectric properties were due to the internal enhancement of the photoresponse associated with strong hole trapping.Theα-Ga_(2)O_(3) film-based UVC detectors can function in self-powered operation mode due to the built-in electric field at the Pt/α-Ga_(2)O_(3) interfaces.At a wavelength of 254 nm and zero applied voltage,the structures exhibit a responsivity of 0.13 mA/W and an external quantum efficiency of 6.2×10^(−2)%.The UVC detectors based on theα-Ga_(2)O_(3) films demonstrate high-speed performance with a rise time of 18 ms in self-powered mode.展开更多
The Chinese-Russian Workshop on Biophotonics and Biomedical Optics 2023 was held online twice on 18–21 September and 25–26 September 2023.The bilateral workshop brought together both Russian and Chinese scientists,e...The Chinese-Russian Workshop on Biophotonics and Biomedical Optics 2023 was held online twice on 18–21 September and 25–26 September 2023.The bilateral workshop brought together both Russian and Chinese scientists,engineers,and clinical researchers from a variety of disciplines engaged in applying optical science,photonics,and imaging technologies to problems in biology and medicine.During the workshops,two plenary lectures and twenty invited presentations were presented.This special issue selects some papers from both Russian and Chinese sides,consisting of one review and seven original research articles.展开更多
The effect of protons(E = 100 keV,F = 5×10^(15) cm^(-2)) exposure on the diffuse reflectance spectra of the SiO_(2 )with different size particles in wavelength range from 250 to 2500 nm have been investigated.Par...The effect of protons(E = 100 keV,F = 5×10^(15) cm^(-2)) exposure on the diffuse reflectance spectra of the SiO_(2 )with different size particles in wavelength range from 250 to 2500 nm have been investigated.Particles were nanosphere,submicrosphere,microsphere and submacrosphere,as well as solid micro-and nanocrystals.The synthesis of the particles was carried out by the formation of silica shells and dissolution of the polystyrene core particles.The surface morphology,surface area and crystal structure of the particles have been investigated.When evaluating the changes of the solar absorptance,it was found that the radiation stability of the micro-and submacro-hollow particles is higher than that of the other nanostructured particles,except for solid microcrystals.The low radiation stability of the hollow microparticles is due to the large void inside the hollow particles where radiation defects are not formed.展开更多
This systematic review and meta-analysis aimed to consolidate information about(1)Pb and Hg concentrations in reindeer(Rangifer tarandus)meat from different Arctic regions and the factors affecting the concentrations ...This systematic review and meta-analysis aimed to consolidate information about(1)Pb and Hg concentrations in reindeer(Rangifer tarandus)meat from different Arctic regions and the factors affecting the concentrations and(2)the effects of Pb and Hg on human health in the Arctic.The study was performed following guidelines outlined in Preferred Reporting Items for Systematic Reviews and Meta-Analyses statements.We performed literature searches using the databases Cochrane Library,CrossRef,CyberLeninka,eLibrary,Embase,Medline,PubMed,and Scopus.A total of 3614publications from January 1980 to November 2023 were scrutinized.Thirty-four relevant studies from Canada,Finland,Greenland(Denmark),Norway,Russia(covering six high latitude regions),Sweden,and the United States were selected for synthesis.The highest Hg concentrations in reindeer meat from Arctic regions were found in samples from Alaska(USA),Canada,Greenland(Denmark),the Nenets Autonomous Okrug(Russia),and Sweden,and the highest Pb concentrations were found in samples from Greenland(Denmark),the Nenets Autonomous Okrug(Russia),Norway,and the Taimyr Peninsula(Russia).The Pb and Hg concentrations in reindeer meat from Finland and the Yamal-Nenets Autonomous Okrug(Russia)were relatively low.The results indicated that extractive industries in Arctic regions are important sources of toxic metals such as Pb and Hg in reindeer meat.展开更多
This study aims to formulate a steady-state mathematical model for a three-dimensional permeable enclosure(cavity)to determine the oil extraction rate using three distinct nanoparticles,SiO_(2),Al_(2)O_(3),and Fe_(2)O...This study aims to formulate a steady-state mathematical model for a three-dimensional permeable enclosure(cavity)to determine the oil extraction rate using three distinct nanoparticles,SiO_(2),Al_(2)O_(3),and Fe_(2)O_(3),in unconventional oil reservoirs.The simulation is conducted for different parameters of volume fractions,porosities,and mass flow rates to determine the optimal oil recovery.The impact of nanoparticles on relative permeability(kr)and water is also investigated.The simulation process utilizes the finite volume ANSYS Fluent.The study results showed that when the mass flow rate at the inlet is low,oil recovery goes up.In addition,they indicated that silicon nanoparticles are better at getting oil out of the ground(i.e.,oil reservoir)than Al_(2)O_(3)and Fe_(2)O_(3).Most oil can be extracted from SiO_(2),Al_(2)O_(3),and Fe_(2)O_(3)at a rate of 97.8%,96.5%,and 88%,respectively.展开更多
Due to the push for carbon neutrality in various human activities,the development of methods for producing electricity without relying on chemical reaction processes or heat sources has become highly significant.Also,...Due to the push for carbon neutrality in various human activities,the development of methods for producing electricity without relying on chemical reaction processes or heat sources has become highly significant.Also,the challenge lies in achieving microwatt-scale outputs due to the inherent conductivity of the materials and diverting electric currents.To address this challenge,our research has concentrated on utilizing nonconductive mediums for water-based low-cost microfibrous ceramic wools in conjunction with a NaCl aqueous solution for power generation.The main source of electricity originates from the directed movement of water molecules and surface ions through densely packed microfibrous ceramic wools due to the effect of dynamic electric double layer.This occurrence bears resemblance to the natural water transpiration in plants,thereby presenting a fresh and straightforward approach for producing electricity in an ecofriendly manner.The generator module demonstrated in this study,measuring 12×6 cm^(2),exhibited a noteworthy open-circuit voltage of 0.35 V,coupled with a short-circuit current of 0.51 mA.Such low-cost ceramic wools are suitable for ubiquitous,permanent energy sources and hold potential for use as self-powered sensors and systems,eliminating the requirement for external energy sources such as sunlight or heat.展开更多
Fluorine containing oxidizers, primarily polymers, are extensively used in pyrotechnic compositions.Fluorinated oxidizers are less explored for metalized propellants and explosives despite a potential advantage of sub...Fluorine containing oxidizers, primarily polymers, are extensively used in pyrotechnic compositions.Fluorinated oxidizers are less explored for metalized propellants and explosives despite a potential advantage of substantial heat release combined with gaseous combustion products. This review summarizes different types of fluorinated oxidizers used in energetic formulations or of potential interest for such systems, including gases, polymers, and inorganic compounds. Types of energetic formulations employing metals and fluoropolymers are discussed in more detail, including methods used to prepare composites and resulting salient features of the obtained materials. Laboratory experiments characterizing such materials, in particular, electron microscopy and thermal analysis, are discussed, showing characteristic morphologies and reaction sequences observed in different metal-fluorinated oxidizer composites. Striking similarities are noted in reaction sequences for diverse compositions hinting at possible similarities in the respective reaction mechanisms. Experiments probing ignition and combustion of metal-fluorinated oxidizer composites in laboratory conditions are also reviewed, including impact, flash heating and shock ignition. Finally, some practical performance tests for energetic formulations are described following by a brief discussion of the reaction mechanisms expected to govern ignition and combustion in various metal-fluorinated oxidizer composites. The conclusions are combined with recommendation for future research in the area of reactive metal-fluorinated oxidizer composites.展开更多
The influence of annealing cycles up to 650 °C on the specific conductivity and hardness（HV） of hot-rolled sheets of Al alloys containing up to 0.5% Zr（mass fraction） was studied.Using analytical calculations...The influence of annealing cycles up to 650 °C on the specific conductivity and hardness（HV） of hot-rolled sheets of Al alloys containing up to 0.5% Zr（mass fraction） was studied.Using analytical calculations of phase composition and experimental methods（scanning electron microscopy,transmission electron microscopy,electron microprobe analysis,etc）,it is demonstrated that the conductivity depends on the content of Zr in the Al solid solution which is the minimum after holding at 450 °C for 3 h.On the other hand,the hardness of the alloy is mainly caused by the amount of nanoparticles of the L12（Al3Zr） phase that defines the retention of strain hardening.It is shown that the best combination of electrical conductivity and hardness values can be reached within an acceptable holding time at the temperature about 450 °C.展开更多
Although alien and invasive plant species have been researched extensively in the European part of Russia,the situation in Siberia is another matter.Hitherto,alien and invasive species in Siberia have not received muc...Although alien and invasive plant species have been researched extensively in the European part of Russia,the situation in Siberia is another matter.Hitherto,alien and invasive species in Siberia have not received much attention because this problem was not especially acute in Siberia.The lack of attention on alien and invasive species in Siberia is attributed to three major reasons：1） Low vegetative productivity and sparse human populations in the Siberian territory have limited botanical research interest in the area.2） Severe Siberian climate likely prevents many alien and invasive species from increasing their distribution into Siberia.3） Most Siberian plant communities have not been human-transformed and thus may be resistant to newcomers.Nevertheless,recent increased economic activities have resulted in increasing plant migration to Siberia,and this process should be monitored.Furthermore,global environmental changes may also have made Siberia more favorable for more alien and invasive species.Currently,research on alien and invasive species has begun in the Altai-Sayan region（Western Siberia） and the Magadan region （Northeastern Asia）.展开更多
Altai (also named Altay in China) Mountain Country (Mountain System) is a unique natural region,located on the border between different floristic regimes of the Boreal and ancient Mediterranean sub-kingdoms,where dist...Altai (also named Altay in China) Mountain Country (Mountain System) is a unique natural region,located on the border between different floristic regimes of the Boreal and ancient Mediterranean sub-kingdoms,where distribution of plant species is actually limited. It is known to have sufficient endemic floral biodiversity in the Northern Asia. Many plants of Altai Mountain System need effective care and proper conservation measures for their survival and longer-term protection. Important Plant Area identified as the IUCN (the International Union for Conservation of Nature),specified criteria attract global attention for protection of floral biodiversity across the world. The records of 71 plant species from the Chinese Altai Mountains attributed to the criterion A and the dark conifer forests of Chinese Altai Mountains satisfied the criterion C,which may help qualify to fulfill the national obligation of the Convention on Biological Diversity.展开更多
An essential stage of mine design is an estimation of the steps of the first and periodic roof caving in longwall mines.Generally,this is carried out using the field experience and can be much enhanced by numerical si...An essential stage of mine design is an estimation of the steps of the first and periodic roof caving in longwall mines.Generally,this is carried out using the field experience and can be much enhanced by numerical simulation.In this work,the finite-difference method was applied coupled with the continuum damage mechanics(CDM)approach to simulate the stress-strain evolution of the rock mass with the underground opening during coal extraction.The steps and stages of roof caving were estimated relying on the numerical simulation data,and they were compared with the field data from several operating mines in the south of the Kuznetsk Basin,Russia.The dependence of the first roof caving step in simulation linearly correlates with field data.The results correspond to the actual roofs of longwall panels of the flat-dipping coal seams and the average rate of face advancement is approximately 5 m/day.展开更多
It is not well known how low temperatures, like a subarctic steppe–tundra climate, influence reproductive traits of ectothermic vertebrates. To begin answering this question, we studied male and female reproductive s...It is not well known how low temperatures, like a subarctic steppe–tundra climate, influence reproductive traits of ectothermic vertebrates. To begin answering this question, we studied male and female reproductive systems of Salamandrella keyserlingii inhabiting a Tomsk population（southeast of Western Siberia）, Russia, in ecological and physiological terms. In males, before spermiation, the testicular size and weight in late April–early May were greatest of all. Spermiation occurred during breeding immigration in spring when mean air temperature was above 10°С, and at the same time rain fell. After spermiation, the testicular size and weight decreased sharply, and the diameter of the vasa deferentia increased. ＂Spawning＂（i.e., simultaneous extrusion of sperm and oviposition） occurred from late April to late May, and this duration fluctuated in temperature and humidity. The testicular size and weight increased in summer. Sperm mass was detected in the testes by the smear method in April–September, except in June when single fragmented unrealized sperm was detected and in July when spermatids were detected. In females, ovarian weight was greatest in spring before ovulation. From late June, vitellogenesis began in ovarian follicles, in which mint green yolks accumulated. Melanin deposited in the surface of the ovary from July when oviducts were hypertrophying. In contrast, some large-sized females did not show any sexual maturity shortly before hibernation（although these females may be subadults）. These results suggest that low temperatures in Siberia induce early timing of gamete maturation in females, but the females＇ reproductive cycle might also be biennial. A reproductive cycle in males was annual with the completion of the gamete maturation process in August.展开更多
The influence of ischemia-reperfusion(I/R)action on pancreatic blood flow(PBF)and the development of acute pancreatitis(AP)in laboratory rats is evaluated in vivo by using the laser speckle contrast imaging(LSCI).Addi...The influence of ischemia-reperfusion(I/R)action on pancreatic blood flow(PBF)and the development of acute pancreatitis(AP)in laboratory rats is evaluated in vivo by using the laser speckle contrast imaging(LSCI).Additionally,the optical properties in norm and under condition of AP in rats were assessed using a modied integrating sphere spectrometer and inverse Monte Carlo(IMC)software.The results of the experimental study of microcirculation of the pancreas in 82 rats in the ischemic model are presented.The data obtained conrm the fact that local ischemia and changes in the blood°ow velocity of the main vessels cause and provoke acute pancreatitis.展开更多
基金Research of the photoelectric properties of theκ(ε)-Ga_(2)O_(3)films was supported by the Russian Science Foundation,grant number 20-79-10043-P.Fabrication of the ultraviolet detectors based on theκ(ε)-Ga_(2)O_(3)layers was supported by the grant under the Decree of the Government of the Rus-sian Federation No.220 of 09 April 2010(Agreement No.075-15-2022-1132 of 01 July 2022)Research of the structural prop-erties of theκ(ε)-Ga_(2)O_(3)was supported by the St.Petersburg State University,grant number 94034685.
文摘High-speed solar-blind short wavelength ultraviolet radiation detectors based onκ(ε)-Ga_(2)O_(3)layers with Pt contacts were demonstrated and their properties were studied in detail.Theκ(ε)-Ga_(2)O_(3)layers were deposited by the halide vapor phase epitaxy on patterned GaN templates with sapphire substrates.The spectral dependencies of the photoelectric properties of struc-tures were analyzed in the wavelength interval 200-370 nm.The maximum photo to dark current ratio,responsivity,detectiv-ity and external quantum efficiency of structures were determined as:180.86 arb.un.,3.57 A/W,1.78×10^(12) Hz^(0.5)∙cm·W^(-1) and 2193.6%,respectively,at a wavelength of 200 nm and an applied voltage of 1 V.The enhancement of the photoresponse was caused by the decrease in the Schottky barrier at the Pt/κ(ε)-Ga_(2)O_(3)interface under ultraviolet exposure.The detectors demon-strated could functionalize in self-powered mode due to built-in electric field at the Pt/κ(ε)-Ga_(2)O_(3)interface.The responsivity and external quantum efficiency of the structures at a wavelength of 254 nm and zero applied voltage were 0.9 mA/W and 0.46%,respectively.The rise and decay times in self-powered mode did not exceed 100 ms.
基金performed within the framework of the State assignment of the IHCE SB RAS,project No.FWRM-2021-0014.
文摘The development of a nanosecond discharge in a pin-to-pin gap filled with air at atmospheric pressure has been studied with high temporal and spatial resolutions from a breakdown start to the spark decay.Positive and negative nanosecond voltage pulses with an amplitude of tens of kilovolts were applied.Time-resolved images of the discharge development were taken with a fourchannel Intensified Charge Coupled Device(ICCD)camera.The minimum delay between the camera channels could be as short as≈0.1 ns.This made it possible to study the gap breakdown process with subnanosecond resolution.It was observed that a wide-diameter streamer develops from the high-voltage pointed electrode.The ionization processes near the grounded pin electrode started when the streamer crossed half of the gap.After bridging the gap by the streamer,a diffuse discharge was formed.The development of spark leaders from bright spots on the surface of the pointed electrodes was observed at the next stage.It was found that the rate of development of the spark leader is an order of magnitude lower than that of the wide-diameter streamer.Long thin luminous tracks were observed against the background of a discharge plasma glow.It has been established that the tracks are adjacent to brightly glowing spots on the electrodes and are associated with the flight of small particles.
基金supported by the Tomsk State University Competitiveness Improvement Program under Grant No.2.4.2.23 IG.
文摘Location awareness in wireless networks is essential for emergency services,navigation,gaming,and many other applications.This article presents a method for source localization based on measuring the amplitude-phase distribution of the field at the base station.The existing scatterers in the target area create unique scattered field interference at each source location.The unique field interference at each source location results in a unique field signature at the base station which is used for source localization.In the proposed method,the target area is divided into a grid with a step of less than half the wavelength.Each grid node is characterized by its field signature at the base station.Field signatures corresponding to all nodes are normalized and stored in the base station as fingerprints for source localization.The normalization of the field signatures avoids the need for time synchronization between the base station and the source.When a source transmits signals,the generated field signature at the base station is normalized and then correlated with the stored fingerprints.The maximum correlation value is given by the node to which the source is the closest.Numerical simulations and results of experiments on ultrasonic waves in the air show that the ultrasonic source is correctly localized using broadband field signatures with one base station and without time synchronization.The proposed method is potentially applicable for indoor localization and navigation of mobile robots.
文摘In mmWave massive multiple-input multiple-output(MIMO)communication systems,the extension of low-complexity narrowband precoding schemes to be operated on wideband systems under frequency-selective channels remains an important challenge at the current time.This paper investigates a low complexity wideband hybrid precoding scheme for mmWave massive MIMO multicarrier systems under a single-user,fully-connected hybrid architecture.We show that the radio frequency(RF)precoding/combining vectors can be directly derived from the eigenvectors of the optimal fully-digital covariance matrix over all subcarriers in order to maximize the sum rate of spectral efficiency.We also suggest a new method that iteratively reduces the residual error between the covariance matrix and the sum of products of precoding matrices over all the subcarriers to improve the performance in the case where the number of RF chains is higher than the number of streams.The results of the simulation show that the proposed schemes’complexity is low compared to the present methods,and their performance can almost reach the upper bound achieved by the optimal full-baseband design.
文摘The study focused on the modification with platinum of dark defective titania obtained via pulsed laser ablation. Both the method of Pt introduction and the nature of the Pt precursor were varied. All samples exhibited similar phase compositions, specific surface areas, and Pt contents. High-resolution transmission electron microscopy coupled with pulsed CO adsorption revealed increased dispersity when photoreduction and the hydroxonitrate complex (Me _(4) N) _(2) [Pt _(2) (OH) _(2) (NO _(3) ) _(8) ] were used. The sample featured a high content of single-atom species and subnano-sized Pt clusters. The X-ray photoelectron spectroscopy results showed that the photoreduction method facilitated the appearance of a larger number of Pt ^(2+) states, which appeared owing to the strong metal-support interaction (SMSI) eff ect of the transfer of electron density from the electron-saturated defects on the TiO _(2) surface to Pt ^(4+) . In the hydrogen evolution reaction, samples with a significant fraction of the Pt ^(2+) ionic component, capable of generating short-lived Pt^(0) single-atom sites under irradiation due to the SMSI eff ect, exhibited the highest photocatalytic activity. The 0.5Pt(C)/TiO_(2) -Ph sample exhibited the highest hydrogen yield with a quantum efficiency of 0.53, retaining its activity even after 8 h of operation.
基金funded by the National University of Mongolia under grant agreement P2023(grant number P2023-4578)。
文摘This study investigates the glacial lake outburst flood(GLOF)hazards in the Tsambagarav mountain range in Western Mongolia,focusing on the Khukhnuruu Valley and its interconnected proglacial lakes.Over the last 30 years,significant glacier retreats,driven by rising temperatures and changing precipitation patterns,have led to the formation and expansion of several proglacial lakes.Fieldwork combined with satellite data and meteorological analysis was used to assess the dynamics of glacier and lake area changes,with particular focus on the flood events of July 2021.The research reveals a substantial reduction in glacier area,particularly in the Khukhnuruu E complex,where glacier area decreased by 19.3%.The study highlights the influence of increasing temperatures and summer precipitation,which have accelerated ice melt,contributing to the expansion and eventual breaching of lakes.Additionally,lake area changes were influenced by the steepness of the terrain,with steeper slopes exacerbating peak discharge during floods.Of the studied seven lakes(Lake 1 to Lake 7),Lake 1 experienced the most dramatic reduction,with a decrease in area by 73.51%and volume by 84.84%,followed by Lake 7.This study underscores the region's vulnerability to climate-induced hazards and stresses the need for a comprehensive early warning system and disaster preparedness measures to mitigate future risks.
基金support of the Russian Science Foundation,grant number 20-79-10043-P.
文摘Detectors were developed for detecting irradiation in the short-wavelength ultraviolet(UVC)interval using high-quality single-crystallineα-Ga_(2)O_(3) films with Pt interdigital contacts.The films ofα-Ga_(2)O_(3) were grown on planar sapphire substrates with c-plane orientation using halide vapor phase epitaxy.The spectral dependencies of the photo to dark current ratio,responsivity,external quantum efficiency and detectivity of the structures were investigated in the wavelength interval of 200−370 nm.The maximum of photo to dark current ratio,responsivity,external quantum efficiency,and detectivity of the structures were 1.16×10^(4) arb.un.,30.6 A/W,1.65×10^(4)%,and 6.95×10^(15) Hz^(0.5)·cm/W at a wavelength of 230 nm and an applied voltage of 1 V.The high values of photoelectric properties were due to the internal enhancement of the photoresponse associated with strong hole trapping.Theα-Ga_(2)O_(3) film-based UVC detectors can function in self-powered operation mode due to the built-in electric field at the Pt/α-Ga_(2)O_(3) interfaces.At a wavelength of 254 nm and zero applied voltage,the structures exhibit a responsivity of 0.13 mA/W and an external quantum efficiency of 6.2×10^(−2)%.The UVC detectors based on theα-Ga_(2)O_(3) films demonstrate high-speed performance with a rise time of 18 ms in self-powered mode.
文摘The Chinese-Russian Workshop on Biophotonics and Biomedical Optics 2023 was held online twice on 18–21 September and 25–26 September 2023.The bilateral workshop brought together both Russian and Chinese scientists,engineers,and clinical researchers from a variety of disciplines engaged in applying optical science,photonics,and imaging technologies to problems in biology and medicine.During the workshops,two plenary lectures and twenty invited presentations were presented.This special issue selects some papers from both Russian and Chinese sides,consisting of one review and seven original research articles.
基金Sponsored by the Ministry of Science and Higher Education of the Russian Federation(Grant No.FZMU-2022-0007 (122082600014-6))the National Key Laboratory of Materials Behavior and Evaluation Technology in Space Environment Fund(Grant No.6142910210208)the Stability Support Fund(Grant No. WDZC-HGD-2022-05)of Harbin Institute of Technology of PR China。
文摘The effect of protons(E = 100 keV,F = 5×10^(15) cm^(-2)) exposure on the diffuse reflectance spectra of the SiO_(2 )with different size particles in wavelength range from 250 to 2500 nm have been investigated.Particles were nanosphere,submicrosphere,microsphere and submacrosphere,as well as solid micro-and nanocrystals.The synthesis of the particles was carried out by the formation of silica shells and dissolution of the polystyrene core particles.The surface morphology,surface area and crystal structure of the particles have been investigated.When evaluating the changes of the solar absorptance,it was found that the radiation stability of the micro-and submacro-hollow particles is higher than that of the other nanostructured particles,except for solid microcrystals.The low radiation stability of the hollow microparticles is due to the large void inside the hollow particles where radiation defects are not formed.
基金partly funded within the framework of project no. NU 2.2.1.24 ONGpart of the Priority 2030 Program。
文摘This systematic review and meta-analysis aimed to consolidate information about(1)Pb and Hg concentrations in reindeer(Rangifer tarandus)meat from different Arctic regions and the factors affecting the concentrations and(2)the effects of Pb and Hg on human health in the Arctic.The study was performed following guidelines outlined in Preferred Reporting Items for Systematic Reviews and Meta-Analyses statements.We performed literature searches using the databases Cochrane Library,CrossRef,CyberLeninka,eLibrary,Embase,Medline,PubMed,and Scopus.A total of 3614publications from January 1980 to November 2023 were scrutinized.Thirty-four relevant studies from Canada,Finland,Greenland(Denmark),Norway,Russia(covering six high latitude regions),Sweden,and the United States were selected for synthesis.The highest Hg concentrations in reindeer meat from Arctic regions were found in samples from Alaska(USA),Canada,Greenland(Denmark),the Nenets Autonomous Okrug(Russia),and Sweden,and the highest Pb concentrations were found in samples from Greenland(Denmark),the Nenets Autonomous Okrug(Russia),Norway,and the Taimyr Peninsula(Russia).The Pb and Hg concentrations in reindeer meat from Finland and the Yamal-Nenets Autonomous Okrug(Russia)were relatively low.The results indicated that extractive industries in Arctic regions are important sources of toxic metals such as Pb and Hg in reindeer meat.
基金The APC of this article is covered by Research Grant YUTP 015LCO-526。
文摘This study aims to formulate a steady-state mathematical model for a three-dimensional permeable enclosure(cavity)to determine the oil extraction rate using three distinct nanoparticles,SiO_(2),Al_(2)O_(3),and Fe_(2)O_(3),in unconventional oil reservoirs.The simulation is conducted for different parameters of volume fractions,porosities,and mass flow rates to determine the optimal oil recovery.The impact of nanoparticles on relative permeability(kr)and water is also investigated.The simulation process utilizes the finite volume ANSYS Fluent.The study results showed that when the mass flow rate at the inlet is low,oil recovery goes up.In addition,they indicated that silicon nanoparticles are better at getting oil out of the ground(i.e.,oil reservoir)than Al_(2)O_(3)and Fe_(2)O_(3).Most oil can be extracted from SiO_(2),Al_(2)O_(3),and Fe_(2)O_(3)at a rate of 97.8%,96.5%,and 88%,respectively.
基金supported by JSPS Kakenhi program(program number 16H06364)and JST CRESTThe authors extend their appreciation to the Deputyship for Research and Innovation,“Ministry of Education”in Saudi Arabia for funding this research(IFKSUOR3-615-5)O.M.also thank the support of Tomsk State University Development Programme(priority-2030)for this work.
文摘Due to the push for carbon neutrality in various human activities,the development of methods for producing electricity without relying on chemical reaction processes or heat sources has become highly significant.Also,the challenge lies in achieving microwatt-scale outputs due to the inherent conductivity of the materials and diverting electric currents.To address this challenge,our research has concentrated on utilizing nonconductive mediums for water-based low-cost microfibrous ceramic wools in conjunction with a NaCl aqueous solution for power generation.The main source of electricity originates from the directed movement of water molecules and surface ions through densely packed microfibrous ceramic wools due to the effect of dynamic electric double layer.This occurrence bears resemblance to the natural water transpiration in plants,thereby presenting a fresh and straightforward approach for producing electricity in an ecofriendly manner.The generator module demonstrated in this study,measuring 12×6 cm^(2),exhibited a noteworthy open-circuit voltage of 0.35 V,coupled with a short-circuit current of 0.51 mA.Such low-cost ceramic wools are suitable for ubiquitous,permanent energy sources and hold potential for use as self-powered sensors and systems,eliminating the requirement for external energy sources such as sunlight or heat.
基金supported in parts by Defense Threat Reduction Agency(HDTRAl-15-1-00240)Air Force Office of Scientific Research(FA9550-16-1-0266)
文摘Fluorine containing oxidizers, primarily polymers, are extensively used in pyrotechnic compositions.Fluorinated oxidizers are less explored for metalized propellants and explosives despite a potential advantage of substantial heat release combined with gaseous combustion products. This review summarizes different types of fluorinated oxidizers used in energetic formulations or of potential interest for such systems, including gases, polymers, and inorganic compounds. Types of energetic formulations employing metals and fluoropolymers are discussed in more detail, including methods used to prepare composites and resulting salient features of the obtained materials. Laboratory experiments characterizing such materials, in particular, electron microscopy and thermal analysis, are discussed, showing characteristic morphologies and reaction sequences observed in different metal-fluorinated oxidizer composites. Striking similarities are noted in reaction sequences for diverse compositions hinting at possible similarities in the respective reaction mechanisms. Experiments probing ignition and combustion of metal-fluorinated oxidizer composites in laboratory conditions are also reviewed, including impact, flash heating and shock ignition. Finally, some practical performance tests for energetic formulations are described following by a brief discussion of the reaction mechanisms expected to govern ignition and combustion in various metal-fluorinated oxidizer composites. The conclusions are combined with recommendation for future research in the area of reactive metal-fluorinated oxidizer composites.
基金Project(RMEF157814X0004)supported by the Ministry of Education and Science of the Russian Federation
文摘The influence of annealing cycles up to 650 °C on the specific conductivity and hardness（HV） of hot-rolled sheets of Al alloys containing up to 0.5% Zr（mass fraction） was studied.Using analytical calculations of phase composition and experimental methods（scanning electron microscopy,transmission electron microscopy,electron microprobe analysis,etc）,it is demonstrated that the conductivity depends on the content of Zr in the Al solid solution which is the minimum after holding at 450 °C for 3 h.On the other hand,the hardness of the alloy is mainly caused by the amount of nanoparticles of the L12（Al3Zr） phase that defines the retention of strain hardening.It is shown that the best combination of electrical conductivity and hardness values can be reached within an acceptable holding time at the temperature about 450 °C.
基金funded by the International Science & Technology Cooperation Program of China(2010DFA92720-06)the Visiting Professorship for Senior International Scientists,Chinese Academy of Sciences(2012T1Z0023)+2 种基金the USDA National Institute of Food and Agriculture(2010-51160-21061)supported by the Chinese Academy of Sciencesin part by the Nevada Agricultural Experiment Station
文摘Although alien and invasive plant species have been researched extensively in the European part of Russia,the situation in Siberia is another matter.Hitherto,alien and invasive species in Siberia have not received much attention because this problem was not especially acute in Siberia.The lack of attention on alien and invasive species in Siberia is attributed to three major reasons：1） Low vegetative productivity and sparse human populations in the Siberian territory have limited botanical research interest in the area.2） Severe Siberian climate likely prevents many alien and invasive species from increasing their distribution into Siberia.3） Most Siberian plant communities have not been human-transformed and thus may be resistant to newcomers.Nevertheless,recent increased economic activities have resulted in increasing plant migration to Siberia,and this process should be monitored.Furthermore,global environmental changes may also have made Siberia more favorable for more alien and invasive species.Currently,research on alien and invasive species has begun in the Altai-Sayan region（Western Siberia） and the Magadan region （Northeastern Asia）.
基金supported by the Xinjiang Committee of Science and Technology (200933122)
文摘Altai (also named Altay in China) Mountain Country (Mountain System) is a unique natural region,located on the border between different floristic regimes of the Boreal and ancient Mediterranean sub-kingdoms,where distribution of plant species is actually limited. It is known to have sufficient endemic floral biodiversity in the Northern Asia. Many plants of Altai Mountain System need effective care and proper conservation measures for their survival and longer-term protection. Important Plant Area identified as the IUCN (the International Union for Conservation of Nature),specified criteria attract global attention for protection of floral biodiversity across the world. The records of 71 plant species from the Chinese Altai Mountains attributed to the criterion A and the dark conifer forests of Chinese Altai Mountains satisfied the criterion C,which may help qualify to fulfill the national obligation of the Convention on Biological Diversity.
基金This work was supported by the Russian Science Foundation,under grant 19-71-00083.Authors also would like to express gratitude to an anonymous reviewer whose comments helped to improve the quality of paper,and editors of the journal.
文摘An essential stage of mine design is an estimation of the steps of the first and periodic roof caving in longwall mines.Generally,this is carried out using the field experience and can be much enhanced by numerical simulation.In this work,the finite-difference method was applied coupled with the continuum damage mechanics(CDM)approach to simulate the stress-strain evolution of the rock mass with the underground opening during coal extraction.The steps and stages of roof caving were estimated relying on the numerical simulation data,and they were compared with the field data from several operating mines in the south of the Kuznetsk Basin,Russia.The dependence of the first roof caving step in simulation linearly correlates with field data.The results correspond to the actual roofs of longwall panels of the flat-dipping coal seams and the average rate of face advancement is approximately 5 m/day.
文摘It is not well known how low temperatures, like a subarctic steppe–tundra climate, influence reproductive traits of ectothermic vertebrates. To begin answering this question, we studied male and female reproductive systems of Salamandrella keyserlingii inhabiting a Tomsk population（southeast of Western Siberia）, Russia, in ecological and physiological terms. In males, before spermiation, the testicular size and weight in late April–early May were greatest of all. Spermiation occurred during breeding immigration in spring when mean air temperature was above 10°С, and at the same time rain fell. After spermiation, the testicular size and weight decreased sharply, and the diameter of the vasa deferentia increased. ＂Spawning＂（i.e., simultaneous extrusion of sperm and oviposition） occurred from late April to late May, and this duration fluctuated in temperature and humidity. The testicular size and weight increased in summer. Sperm mass was detected in the testes by the smear method in April–September, except in June when single fragmented unrealized sperm was detected and in July when spermatids were detected. In females, ovarian weight was greatest in spring before ovulation. From late June, vitellogenesis began in ovarian follicles, in which mint green yolks accumulated. Melanin deposited in the surface of the ovary from July when oviducts were hypertrophying. In contrast, some large-sized females did not show any sexual maturity shortly before hibernation（although these females may be subadults）. These results suggest that low temperatures in Siberia induce early timing of gamete maturation in females, but the females＇ reproductive cycle might also be biennial. A reproductive cycle in males was annual with the completion of the gamete maturation process in August.
基金the nancial sup-port of the Project No.13.2251.21.0009 of the Ministry of Science and Higher Education of the Russian Federation.
文摘The influence of ischemia-reperfusion(I/R)action on pancreatic blood flow(PBF)and the development of acute pancreatitis(AP)in laboratory rats is evaluated in vivo by using the laser speckle contrast imaging(LSCI).Additionally,the optical properties in norm and under condition of AP in rats were assessed using a modied integrating sphere spectrometer and inverse Monte Carlo(IMC)software.The results of the experimental study of microcirculation of the pancreas in 82 rats in the ischemic model are presented.The data obtained conrm the fact that local ischemia and changes in the blood°ow velocity of the main vessels cause and provoke acute pancreatitis.
