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Parameter of dielectric loss distribution in the new model for complex conductivity based on Havriliak-Negami formula

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Journal of Advanced Dielectrics 2020年第1期10卷 34-41页

作者： yu.I.yurasov A.v.Nazarenko Federal Research Centre The Southern Scientific Centre of the Russian Academy of Sciences Chekhov av.Rostov-on-DonRussian Federation Research Institute of Physics of Southern Federal University Rostov-on-Don Russian Federation

This paper is focused on the comparison of the results of various approximation models describing the frequency dependences of the dielectric constanε'/ε_(0)(f)andε"/ε_(0)(f),the tangent of the loss angle tgδ(f)T and the electrical conductivityγ'(f)T andγ"(f)T of nonlinear *** classic ferroelectric material of the PZT system with x=0.50 was chosen as the object of *** on the analysis of temperature-frequency dependences of the“empirical”parametersαandβ,a regularity has been revealed that allows them to be calculated.A new relationship has been established through the parameterα,which allows to relate the temperature and frequency dependences of the complex electrical conductivity asω→∞and asω→0 in the Havriliak-Negami approximation models and in the new model for the description of the complex electrical conductivityγ*.It is shown thatαis a parameter of the temperature-frequency distribution of dielectric *** the obtained expressions,a new theoretical description of experimental spectra having a relaxation character was *** has been proven that the use of the new model makes it possible to accurately describe the set of studied spectra,including the high and low frequencies,in the frequency range from 10^(-3) to 10^(8) Hz.

关键词： Nonlinear dielectrics reach-through conductivity relaxation Havriliak-Negami model complex conductivity

Effects of fibers on expansive shotcrete mixtures consisting of calcium sulfoaluminate cement,ordinary Portland cement,and calcium sulfate

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Journal of Rock Mechanics and Geotechnical Engineering 2018年第2期10卷 212-221页

作者： H.yu L.Wu W.v.Liu Y.Pourrahimian School of Mining and Petroleum Engineering Department of Civil and Environmental Engineering University of Alberta

The mining industry often uses shotcrete for ground stabilization. However, cracking within shotcrete is commonly observed, which delays production schedules and increases maintenance costs. A possible crack reduction method is using expansive shotcrete mixture consisting of calcium sulfoaluminate cement(CSA), ordinary Portland cement(OPC), and calcium sulfate(CS) to reduce shrinkage. Furthermore, fibers can be added to the mixture to restrain expansion and impede cracking. The objective of this paper is to study the effects of nylon fiber, glass fiber, and steel fiber on an expansive shotcrete mixture that can better resist cracking. In this study, parameters such as density, water absorption, volume of permeable voids, unconfined compressive strength(UCS), splitting tensile strength(STS), and volume change of fiber-added expansive mixtures were determined at different time periods(i.e. the strengths on the 28 th day, and the volume changes on the 1 st, 7 th, 14 th, 21 st, and 28 th days). The results show that addition of fibers can improve mixture durability, in the form of decreased water absorption and reduced permeable pore space content. Moreover, the expansion of the CSA-OPC-CS mixture was restrained up to50% by glass fiber, up to 43% by nylon fiber, and up to 28% by steel fiber. The results show that the STS was improved by 57% with glass fiber addition, 43% with steel fiber addition, and 38% with nylon fiber addition. The UCS was also increased by 31% after steel fiber addition, 26% after nylon fiber addition, and16% after glass fiber addition. These results suggest that fiber additions to the expansive shotcrete mixtures can improve durability and strengths while controlling expansion.

关键词： Shotcrete Restrained expansion Fibers Calcium sulfoaluminate cement(CSA) Ordinary Portland cement(OPC) Calcium sulfate(CS)

Understanding the mechanisms of friction stir welding based on computer simulation using particles

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Defence Technology（防务技术） 2018年第6期14卷 643-656页

作者： A.yu.Smolin E.v.Shilko S.v.Astafurov E.A.Kolubaev G.M.Eremina S.G.Psakhie Institute of Strength Physics and Materials Science SB RAS Tomsk634055Russia Tomsk State University Tomsk634050Russia Skolkovo Institute of Science and Technology Skolkovo143025Russia

Friction stir welding(FSW) is a novel technique for joining different materials without melting. In FSW the welded components are joined by stirring the plasticized material of the welded edges with a special rotating pin plunged into the material and moving along the joint line. From the scientific point of view,the key role of the FSW processes belongs to formation of the special plasticized conditions and activation of physical mechanisms of mixing the materials in such conditions to produce the strong homogeneous weld. But it is still a lack of complete understanding of what are these conditions and *** paper is devoted to understanding the mechanisms of material mixing in conditions of FSW based on a computer simulation using particles. The movable cellular automaton method(MCA), which is a representative of the particle methods in mechanics of materials, was used to perform all ***, material flow including material stirring in FSW is simulated using computational fluid mechanics or smoothed particle hydrodynamics, which assume that the material is a continuum and does not take into account the material structure. MCA considers a material as an ensemble of bonded particles. Breaking of inter-particle bonds and formation of new bonds enables simulation of crack nucleation and healing, as well as mass mixing and *** paper consists of two main parts. In the first part, the simulations in 2 D statements are performed to study the dynamics of friction stir welding of duralumin plates and influence of different welding regimes on the features of the material stirring and temperature distribution in the forming welded joints. It is shown that the ratio of the rotational speed to the advancing velocity of the tool has a dramatic effect on the joint quality. A suitable choice of these parameters combined with additional ultrasonic impact could considerably reduce the number of pores and microcracks in the weld without significa

关键词： Friction stir welding Plastic flow Deformation mechanisms Simulation Particle method

Passive vectoring of entomopathogenic fungus Beauveria bassiana among the wax moth Galleria mellonella larvae by the ectoparasitoid Habrobracon hebetor females

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Insect Science 2018年第4期25卷 643-654页

作者： vadim yu. Kryukov Natalia A. Kryukova Maksim v. Tyurin Olga N. Yaroslavtseva viktor v. Glupov Institute of Systematics and Ecology of Animals Siberian Branch of Russian Academy of Science Novosibirsk Russia

Females of the ectoparasitoid Habrobracon hebetor attack and envenomate numerous host individuals during oviposition. The vectoring of the entomopathogenic fungus Beauveria bassiana during the adhesion stage by ectoparasitoid females among the wax moth larvae Galleria mellonella was explored under laboratory conditions. vectoring occurred both from infected parasitoids to wax moth larvae and from infected to healthy wax moth larvae by parasitoids. The efficacy of vectoring in both cases was dose dependent. Parasitoid females were unable to recognize infected larvae in a labyrinth test. In addition, the presence of H. hebetor females significantly （1.5-13 fold） increased the mycoses level in clusters of G. mellonella, with 40% of the larvae infected with ftmgal conidia. Envenomation by H. hebetor increased conidia germination on the cuticles of the wax moth larvae by 4.4 fold. An enhanced germination rate （2 fold） was registered in the n- hexane epicuticular extract of envenomated larvae compared to that of healthy larvae. Both envenomation and mycoses enhanced the phenoloxidase （PO） activity in the integument of G. mellonella and, in contrast, decreased the encapsulation rate in hemolymphs. We hypothesize that changes in the integument property and inhibition of cellular immunity provide the highest infection efficacy of entomopathogenic fungi with H. hebetor.

关键词： Galleria mellonella immunity integuments mycoses parasitoid vectoring

Decomposition of carbon dioxide hydrate in the samples of natural coal with different degrees of metamorphism

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Chinese Journal of Chemical Engineering 2020年第2期28卷 492-501页

作者： vyacheslav G. Smirnov valeriy v. Dyrdin Andrey yu. Manakov Zinfer R. Ismagilov Kuzbass State Technical University Vesennaya str.28Kemerovo 650000Russian Federation Nikolaev Institute of Inorganic Chemistry SB RAS Ac.Lavrentiev ave.3Novosibirsk 630090Russian Federation Novosibirsk State University Pirogov Str.2Novosibirsk 630090Russian Federation Institute of Coal Chemistry and Material Science SB RAS Sovetsky ave.18Kemerovo 650000Russian Federation

Methane and carbon dioxide hydrates are one of the possible forms in which these gases exist in natural coal(for more detailed discussion see Refs [1,2]). In this work, the decomposition of carbon dioxide hydrate in five samples of natural coal differing from each other in metamorphism degree was investigated experimentally. Carbon dioxide hydrate dispersed in coals was synthesized from water adsorbed in these coals. During a linear temperature rise in an autoclave with the coal + hydrate sample the hydrate decomposition manifests itself as a step of increase in gas pressure, accompanied by a decrease/stabilization of the temperature of coal sample. The dependencies of the amount of hydrate formed on initial coal humidity and on gas pressure during hydrate formation were studied. It was demonstrated that each coal sample is characterized by its own humidity threshold below which hydrate formation in natural coal is impossible. With an increase in gas pressure, the amount of water transformed into hydrate increases. For the studied coal samples, the decomposition of carbon dioxide hydrates proceeds within a definite temperature and pressure range, and this range is close to the curve of phase equilibrium for bulk hydrate.

关键词： Gas hydrate Carbon dioxide Coal Coal rank Phase transformation Coal bed gas

Effect of Ta_(2)O_(5)nanoparticles on bioactivity,composition,structure,in vitro and in vivo behavior of PEO coatings on Mg-alloy

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Journal of Magnesium and Alloys 2024年第6期12卷 2360-2379页

作者： D.v.Mashtalyar I.M.Imshinetskiy v.v.Kashepa K.v.Nadaraia M.A.Piatkova A.I.Pleshkova K.A.Fomenko A.yu.Ustinov S.L.Sinebryukhov S.v.Gnedenkov Institute of Chemistry Far Eastern BranchRussian Academy of SciencesVladivostok690022Russia Far Eastern Federal University Vladivostok690950Russia Regional Clinical Dermatovenerological Dispensary Vladivostok690033Russia

The present study investigates the physical and chemical characteristics,behavior in vitro and in vivo,and biocompatibility of coatings containing Ta_(2)O_(5),which are obtained by plasma electrolytic oxidation(PEO)on MA8 magnesium *** obtained coatings demonstrate in vivo biocompatibility and in vitro *** to the base PEO coating,the layers containing Ta_(2)O_(5)facilitate the development of apatite in simulated body fluid,suggesting that the inclusion of nanoparticles improves bioactivity of the *** was found that incorporation of Ta_(2)O_(5)nanoparticles increases roughness and porosity of the formed layers by increasing particle concentration in electrolytes for the PEO process contributing to sufficient soft tissue ingrowth in *** on in vivo studies,these coatings also provide favorable tissue response and minimal inflammatory reaction in comparison with the bare magnesium alloy due to protection of living tissues from deleterious corrosion events of magnesium implant such as local alkalization and intense hydrogen *** results obtained in the present study concluded biocompatibility,tissue integration of the PEO coatings containing Ta_(2)O_(5)nanoparticles making them a promising protective layer for biodegradable magnesium implants.

关键词： Plasma electrolytic oxidation Bioactive coatings Tantalum pentoxide Simulated body fluid(SBF) Apatite formation Histology

Expansion of Juniperus sibirica *** a response to climate change and associated effect on mountain tundra vegetation in the Northern Urals

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Journal of Mountain Science 2020年第10期17卷 2339-2353页

作者： Andrey A.GRIGORIEv yulia v.SHALAUMOvA Olga v.EROKHINA Svetlana yu.SOKOvNINA Elizaveta I.vATOLINA Martin WILMKING Institute of Plant and Animal Ecology UB RAS Laboratory of Geoinformation TechnologyEkaterinburgRussia Institute of Industrial Ecology UB RAS Laboratory of Mathematical Modeling in Ecology and MedicineEkaterinburgRussia Institute of Plant and Animal Ecology UB RAS Laboratory of Vegetation and Mycobiota BiodiversityEkaterinburgRussia Institute of Plant and Animal Ecology UB RAS Laboratory of Dynamics of Arctic EcosystemsLabytnangiRussia Department of Forest Taxation and Forest Management Institute of Forest and Nature ManagementUral state Forest Engineering UniversityEkaterinburgRussia Institute for Botany and Landscape Ecology Greifswald UniversityGreifswaldGermany

Shrub expansion into arctic and alpine tundra is one of the prominent vegetation changes currently *** studied the expansion of shrub vegetation into high elevation tundra in the Kvarkush Range of the Northern Ural mountains,*** structure analysis of the dominant shrub Juniperus sibirica *** to support ongoing upslope advance of shrubs,a process particularly active in the second half of the 20 th *** found a close connection between the expansion of shrub vegetation and the general change in climatic conditions of the cold season(months with mean airtemperature below 0°Сfrom November to March).In general,the greatest influence on the distribution of *** is exerted by the climate conditions of the beginning(November-January)and the end(March)of the cold *** increasing elevation,the correlation coefficients between the establishment of *** shrubs and the precipitation of the beginning of the cold season increased,and reached maximum values at the top elevation level of the study ***,the upwards shift of *** into typical mountain tundra does not lead to changes in the ecological structure of vegetation at this stage,but simply a decrease in the area of mountain tundra.

关键词： Juniperus sibirica Expansion Tundra vegetation Plant communities Climate changes Northern Ural mountains

Introduction to the Special Issue on Advances in Biophotonics and Biomedical Optics:Part II

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Journal of Innovative Optical Health Sciences 2022年第1期15卷 29-31页

作者： Polina Dyachenko(Timoshina) Tingting yu Dan Zhu valery v.Tuchin Research-Educational Institute of Optics and Biophotonics Saratov State University Saratov 410012Russia Britton Chance Center for Biomedical Photonics Wuhan National Laboratory for Optoelectronics Huazhong University of Science and Technology Wuhan 430074 P.R.China MoE Key Laboratory for Biomedical Photonics School of Engineering Sciences Huazhong University of Science and Technology Wuhan 430074 P.R.China

The 9th Chinese–Russian Workshop on Biophotonics and Biomedical Optics was held online on 28–30 September *** 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 *** the workshop,2 plenary lectures,35 invited presentations,5 oral presentations,and 8 internet reports were *** special issue selects some papers from the attendees and includes both research and review articles.

关键词： photonics Russian Biomedical

Karite-diamond fossil:A new type of natural diamond

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Geoscience Frontiers 2020年第4期11卷 1163-1174页

作者： T.G.Shumilova v.v.Ulyashev v.A.Kazakov S.I.Isaenko S.A.Svetov S.yu.Chazhengina N.S.Kovalchuk Institute of Geology of Komi Scientific Centre of the Ural Branch of the Russian Academy of Sciences Pervomayskaya St.54Syktyvkar167982Russia Hawaii Institute of Geophysics and Planetology University of Hawaii at Manoa1680 East-West RoadHonoluluHI96822USA SSC FSUE Keldysh Research Centre Onezhskaya8125438MoscowRussia Institute of Geology of the Karelian Research Centre of the Russian Academy of Sciences Petrozavodsk11 Pushkinskaya StreetRussia

Impact diamond is one of perspective natural type of superhard carbon materials,forming huge resources sometimes,such as Popigai impact structure counting the largest diamond storage on the *** present,there are two known types of impact diamonds-after-graphitic and after-coal varieties formed from different carbon *** we present for the first time a new impact diamond type-diamond fossils,named by "karite",formed about 70 Ma from unmetamorphosed organics in the giant Kara impact crater(Pay-Khoy,Russia).A full complex of the diamond fossil characteristics is described proving its nature and phase *** is presented with supernanocrystalline diamond aggregates,nicely preserves tiny cell morphology and relict features of lignin and *** diamond fossils are spread widely through the Kara impactites,point to possible wider distribution of impact diamonds within large impact occurrences around the world,can be used for impact modeling,astrobiological and material studies.

关键词： Astroblemes Impact diamonds Fossils Diamond paramorphs Astrobiology