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The state of gold in phases of the Cu-Fe-S system:In situ X-ray absorption spectroscopy study

Geoscience Frontiers 2023年第3期14卷 103-116页

作者： Boris R.Tagirov Olga N.Filimonova Alexander L.Trigub Ilya V.Vikentyev Elena V.Kovalchuk Maximilian S.Nickolsky andrey a.shiryaev Vladimir L.Reukov Dmitry A.Chareev Institute of Geology of Ore Deposits(IGEM RAS) 35Staromonetnyi per119017 MoscowRussia National Research Centre‘Kurchatov Institute’ 1Akademika Kurchatova pl123182 MoscowRussia Institute of Physical Chemistry and Electrochemistry(IPCE RAS) 31Leninsky Prospect119071 MoscowRussia Institute of Experimental Mineralogy(IEM RAS) 142432 ChernogolovkaMoscow RegionRussia

Chalcopyrite and bornite are the main Au-bearing minerals at Cu porphyry deposits,volcanogenic massive sulfide(VMS)deposits,Cu-Ni deposits of the mafic magmatic complexes,and ores of submarine sulfide *** and intermediate solid solutions with wide compositional variations(bnss and iss–high-temperature chalcopyrite,correspondingly),which can scavenge economic concentrations of Au,appear in the Cu-Fe-S system at ore-forming ***,the state of Au in bnss and iss is yet *** solve this conundrum,we synthesized samples with net chemical composition of bnss and iss,studied them by in situ X–ray absorption spectroscopy(XAS),and used the experimental data to explain the Au distribution among natural ore-forming *** sulfide samples were obtained at 495–700℃ in Au-saturated system by means of salt flux *** bnss contained1.2–1.6 log units more Au than iss:up to 18 wt.%Au in bnss vs 0.4 wt.%Au in iss at 700*** increase of temperature resulted in the sharp increase of Au concentration in both phases,1 log unit per 100℃ at f(S2)close to S_((l)) *** of Au L_(3)-edge spectra recorded at 25–675℃ revealed that at 25℃ Au exists mainly in the metallic *** t>500℃ the spectral features of Audisappear,and “chemically bound”Au *** Au form of occurrence in the iss field is interpreted as Au-bearing clusters with a stromeyerite-like(CuAgS)*** Cu_(2–x)S and bnss contain Au in a mixture of stromeyeritelike and petrovskaite-like(Au_(0.8)Ag_(1.2)S)*** chemical composition of both forms is close to CuAuS,where the nearest Au neighbors are two S atoms at R_(Au-S)=2.34–2.36Å.Results of the present study allow to determine the state of Au and its concentration in the main Cu-bearing minerals of sulfide ores as a function of the T-f(S_(2))-compositional *** to the sharp increase of the CuAuS clusters stability with increasing temperature,in high-temperature ores formed at t>350℃ A

关键词： “Invisible”gold Bornite solid solution Intermediate solid solution Digenite Chalcopyrite X-ray absorption spectroscopy

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Early Jurassic Climate Warming in Eastern Siberia: First Macrofloristic Evidence from Irkutsk Basin, Russia

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Acta Geologica Sinica(English Edition) 2024年第4期98卷 1035-1050页

作者： andrey FROLOV Irina MASHCHUK Institute of the Earth's Crust Siberian Branch of the Russian Academy of SciencesIrkutsk664033Russia

Numerous new records of Ferganiella, Podozamites, and Schidolepium, including a new species, Ferganiella ivantsovii sp. nov., are described from the Early Jurassic(Toarcian) Middle Subformation of the Prisayan Formation from the Euro-Sinian paleofloristic region in the Irkutsk Basin, Eastern Siberia, Russia. An analysis of the paleogeographic distribution of Ferganiella and Podozamites shows that both genera were the most diverse and numerous in the East Asian province of the Euro-Sinian region and in the Northern Chinese province of the Siberian region during the Early and Middle Jurassic. These phytochoria were located in the subtropical and temperate subtropical climate zones, which allows us to consider Ferganiella and Podozamites as thermophilic plants, which are important indicators of the Early Toarcian climatic optimum. Their abundance in the Irkutsk Basin thus may indicate Early Toarcian warming;further abundant Schidolepium cones, which produced Araucariacites pollen, typical for Euro-Sinian flora complement the scenario. Thus, the new finds are the first macrofloristic indicators of the Toarcian climatic optimum in the Irkutsk Basin.

关键词： paleobotany Ferganiella Podozamites Schidolepium Toarcian climatic optimum paleobiogeography Siberian paleofloristic region Irkutsk

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On Differential Equations of Integrable Billiard Tables

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Acta Mathematica Sinica,English Series 2024年第1期40卷 417-424页

作者： Vladimir DRAGOVIC andrey E.MIRONOV Department of Mathematical Sciences The University of Texas at DallasRichardson TXUSA Mathematical Institute SANU BelgradeSerbia Novosibirsk State University NovosibirskRussia Sobolev Institute of Mathematics of the Siberian Branch of the Russian Academy of Sciences NovosibirskRussia

We introduce a method to find differential equations for functions which define tables,such that associated billiard systems admit a local first *** illustrate this method in three situations:the case of(locally)integrable wire billiards,for finding surfaces in R^(3)with a first integral of degree one in velocities,and for finding a piece-wise smooth surface in R^(3)homeomorphic to a torus,being a table of a billiard admitting two additional first integrals.

关键词： Polynomial first integrals wire billiards piece-wise smooth surfaces

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Comparison of extraction abilities of deep eutectic solvents and aqueous acid solutions for extraction of rare earths and transition metals

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Journal of Rare Earths 2024年第6期42卷 1157-1164,I0006页

作者： Svetlana Drogobuzhskaya Margarita Frolova andrey Shishov Nikita Tsvetov Tananaev Institute of Chemistry-Subdivision of the Federal Research Centre《Kola Science Centre of the Russian Academy of Sciences》 18420926a AcademgorodokApatityRussia Murmansk State Technical University 183010Sportivnaja str.13MurmanskRussia Department of Analytical Chemistry Institute of ChemistrySaint Petersburg State UniversitySpbSU.1990347/9 Universitetskaya embSt.Petersburg Russia

In recent years,deep eutectic solvents have attracted increasing interest as effective extractants for the separation of both organic substances and metals from various ***-based deep eutectic solvents are most often used as extractants for the extraction of *** this work,for the first time,the extraction efficiency of transition metals and rare earth elements(Y,Zr,Nb,La,Ce,Pr,Nd,Sm,Eu,Gd,Tb,Dy,Ho,Er,Tm,Yb,Lu,Hf and Ta)from mining tailings and Na,K,Ca,Mg,Cu,Fe,Mn,Pb,Ba,Ni and Sr from biodiesel samples using acidic deep eutectic solvents and saturated aqueous solutions of the same acids(malonic,malic,tartaric and citric)is *** this,deep eutectic solvents based on acids and their aqueous saturated solutions were prepared and *** prepared mixtures were analyzed by IR spectroscopy to confirm the formation of eutectic *** such as the density and viscosity of the resulting mixtures were also investigated,as this can be of key importance for the efficiency of metal *** extraction of rare earth metals from mining tailings took a long time(up to several days),while the extraction of metals from fuel took no more than 30 *** emission spectral methods were used as an analysis *** is shown that the extraction efficiency with aqueous solutions is better than that with eutectic solvents,which casts doubt on the need for deep eutectic solvents use in this area.

关键词： Deepeutectic solvent Metal separation Elemental analysis Rare earth metals Biodiesel

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Modeling of Leachate Propagation in a Municipal Solid Waste Landfill Foundation

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Fluid Dynamics & Materials Processing 2024年第6期20卷 1407-1424页

作者： Nadezhda Zubova andrey Ivantsov Institute of Continuous Media Mechanics of the Ural Branch Russian Academy of SciencePerm614013Russia

The study deals with the numerical modeling of leachate distribution in the porous medium located under a municipal solid waste disposal landfill(MSWLF).The considered three-layer system is based on geological data obtained from field *** simplicity,the problem is investigated by assuming a two-component ***,the heat produced by landfills due to biological and chemical processes and the thermal diffusion mechanism contributing to pollution transport are taken into *** numerical modeling of the propagation of leachate in the considered layered porous medium is implemented for parameters corresponding to natural soil and for the case where disruption of the porous medium structure is due to cracks formation or *** latter is accompanied by an increase in rock *** this case,the emergence of multi-vortex flow in the layer of high permeability is observed to substantially influence the bottom layers and cause intensification of the leachate *** effects should be taken into account when estimating the parameters and properties of materials required for the construction of solid waste disposal facilities.

关键词： Three-layer porous medium binary mixture diffusion thermal diffusion

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Energy-efficient joint UAV secure communication and 3D trajectory optimization assisted by reconfigurable intelligent surfaces in the presence of eavesdroppers

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Defence Technology（防务技术） 2024年第1期31卷 537-543页

作者： Huang Hailong Mohsen Eskandari andrey V.Savkin Wei Ni The Department of Aeronautical and Aviation Engineering The Hong Kong Polytechnic UniversityHong KongChina School of Electrical Engineering and Telecommunications University of New South WalesSydney2052Australia Data61 CSIROAustralia

We consider a scenario where an unmanned aerial vehicle(UAV),a typical unmanned aerial system(UAS),transmits confidential data to a moving ground target in the presence of multiple *** friendly reconfigurable intelligent surfaces(RISs) help to secure the UAV-target communication and improve the energy efficiency of the *** formulate an optimization problem to minimize the energy consumption of the UAV,subject to the mobility constraint of the UAV and that the achievable secrecy rate at the target is over a given *** present an online planning method following the framework of model predictive control(MPC) to jointly optimize the motion of the UAV and the configurations of the *** effectiveness of the proposed method is validated via computer simulations.

关键词： Unmanned aerial systems(UASs) Unmanned aerial vehicle(UAV) Communication security Eaves-dropping Reconfigurable intelligent surfaces(RIS) Autonomous navigation and placement Path planning Model predictive control

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Preface to the Special Issue on Modeling and Data Analysis Methods for the SMILE mission

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Earth and Planetary Physics 2024年第1期8卷 1-4页

作者： TianRan Sun Hyunju Connor andrey Samsonov National Space Science Center Chinese Academy of SciencesBeijing 100190China NASA Goddard Space Flight Center US Mullard Space Science Laboratory University College LondonUK

The SMILE(Solar wind Magnetosphere Ionosphere Link Explorer)project(http://***/smile/,https://***/web/smile/mission)is a joint spacecraft mission of the European Space Agency(ESA)and the Chinese Academy of Sciences(CAS)with an expected launch in *** aims to study the global interactions of solar wind–magnetosphere–ionosphere innovatively by imaging the Earth’s magnetosheath and cusps in soft X-rays and the northern auroral region in ultraviolet(UV)while simultaneously measuring plasma and magnetic field parameters in the solar wind and magnetosheath along a highly-elliptical and highly-inclined *** special issue is composed of 22 articles,presenting recent progress in modeling and data analysis techniques developed for the SMILE *** this preface,we categorize the articles into the following seven topics and provide brief summaries:(1)instrument descriptions of the Soft X-ray Imager(SXI),(2)numerical modeling of the X-ray signals,(3)data processing of the X-ray images,(4)boundary tracing methods from the simulated images,(5)physical phenomena and a mission concept related to the scientific goals of SMILE-SXI,(6)studies of the aurora,and(7)ground-based support for SMILE.

关键词： SMILE X-ray imaging magnetosphere auroral ionosphere

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Optimal rejection of bounded perturbations in linear leader-following consensus protocol: invariant ellipsoid method

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Science China(Information Sciences) 2024年第8期67卷 24-34页

作者： Siyuan WANG andrey POLYAKOV Min LI Gang ZHENG Driss BOUTAT INSA Centre Val de Loire INRIA

The objective of the invariant ellipsoid method is to minimize the smallest invariant and attractive set of a linear control system operating under the influence of bounded external disturbances. This study extends the application of this method to address the leader-following consensus problem. Initially, a linear control protocol is designed for the multi-agent system in the absence of disturbances. Subsequently, in the presence of bounded disturbances, by employing a similar linear control protocol, a necessary and sufficient condition is introduced to derive the optimal control parameters for the multi-agent system such that the state of followers converges to and remains in a minimal invariant ellipsoid around the state of the leader.

关键词： multi-agent system leader-following consensus invariant ellipsoid disturbance

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Consideration of the influence of supports in modeling the electromagnetic fields of 25 kV traction networks under emergency conditions

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Global Energy Interconnection 2024年第4期7卷 528-540页

作者： Konstantin Suslov andrey Kryukov Ekaterina Voronina Pavel Ilyushin Department of Hydropower and Renewable Energy National Research UniversityMoscow Power Engineering InstituteMoscow 11250Russia Department of Power Supply and Electrical Engineering Irkutsk National Research Technical UniversityIrkutsk 664074Russia Department of Transport Electric Power Irkutsk State Transport UniversityIrkutsk 664074Russia Department of Research on the Relationship between Energy and the Economy Energy Research Institute of the Russian Academy of SciencesMoscow 117186Russia

Single-phase 25 kV traction networks of electrified alternating current(AC)railways create electromagnetic fields(EMFs)with significant levels of *** most intense magnetic fields occur when short circuits exist between the contact wire and rails or *** the short duration of exposure,they can adversely affect electronic devices and induce significant voltages in adjacent power lines,which is dangerous for operating *** numerous investigations have focused on modeling the EMF of traction networks and power lines,the challenge of determining the three-dimensional electromagnetic fields near metal supports during the flow of a short-circuit current through them is yet to be *** this case,the field has a complex spatial structure that significantly complicates the calculations of *** study proposes a methodology,algorithms,software,and digital models for determining the EMF in the described emergency *** the modeling process,the objects being studied were represented by segments of thin wires to analyze the distribution of the electric charge and calculate the intensities of the electric and magnetic *** approach was implemented in the Fazonord software,and the modeling results show a substantial increase in EMF levels close to the support,with a noticeable decrease in the levels as the distance from it *** procedure implemented in the commercial software Fazonord is universal and can be used to determine electromagnetic fields at any electrical power facility that includes live parts of limited *** on the proposed procedure,the EMF near the supports of overhead power lines and traction networks of various designs could be determined,the EMF levels at substations can be calculated,and the influence of metal structures located near traction networks,such as pedestrian crossings at railway stations,can be considered.

关键词： Power supply systems AC railways Emergency conditions Electromagnetic fields near supports Modeling Electromagnetic safety

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Juvenile survival curves in a solitary ground squirrel with a prolonged hibernation:effects of individual characteristics,environment,and maternal investment

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Current Zoology 2024年第1期70卷 13-23页

作者： Nina A.Vasilieva Liudmila E Savinetskaya andrey V.Tchabovsky A.N.Severtsov Institute of Ecology and Evolution Russian Academy of SciencesMoscow 119071Russia

Juvenile survival is a key life-history influence on population dynamics and adaptive *** analyzed the effects of individual chara-cteristics,early environment,and maternal investment on juvenile survival in a large solitary hibernating rodent-yellow ground squirrel Spermophilus fulvus using Cox mixed-effects *** 48%of weaned pups survived to dispersal and 17%survived to *** life expectancy was primarily determined by individual characteristics and,to a lesser extent,by the early *** strongest and pos-itive predictor of juvenile survival was body mass which crucially affected mortality immediately after *** suffered higher mortality than females after the onset of dispersal;however,the overall difference between sexes was partly masked by high rates of mortality in the first days after emergence in both *** emerged juveniles had lower life expectancy than the earliest *** overall effect of local juvenile density was *** lactation did not enhance juvenile survival:Pups nursed longer survived shorter than the young nursed for a shorter *** findings support the hypothesis that females of *** cannot effectively regulate maternal expenditures to mitigate the effects of unfavorable conditions on their *** strategy to deal with seasonal time constraints on life history in female *** suggests an early termination of maternal care at the cost of juvenile quality and *** female reproductive strategy corresponds to a"fast-solitary"life of folivorous desert-dwelling *** and other solitary ground squirrels with prolonged hibernation.

关键词： early-life conditions ground squirrels hibernation juvenile mortality maternal investment survival curves

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