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Three-dimensional Convection in an Inclined Porous Layer Subjected to a Vertical Temperature Gradient

Fluid dynamics & Materials Processing 2024年第9期20卷 1957-1970页

作者： Ivan Shubenkov Tatyana Lyubimova evgeny Sadilov Computational Fluid dynamics Laboratory Institute of Continuous Media Mechanics UB RASPerm614068Russia Theoretical Physics department Perm State UniversityPerm614990Russia

In this paper,we study the onset and development of three-dimensional convection in a tilted porous layer saturated with a *** layer is subjected to a gravitational field and a strictly vertical temperature ***,problems of thermal convection in tilted porous media saturated with a liquid are studied by assuming constant different temperatures at the boundaries of the layer,which prevent these systems from supporting conductive(non-convective)*** boundary conditions considered in the present work allow a conductive state and are representative of typical geological *** an earlier work,we carried out a linear stability analysis of the conductive *** was shown that at any layer tilt angles,the most dangerous type of disturbances are longitudinal ***,a non-zero velocity component exists in *** the present work,threedimensional non-linear convection regimes are *** original three-dimensional problem is reduced to two-dimensional one with an analytical expression for the velocity z-component v_(z)=v_(z)(x,y).It is shown that the critical Rayleigh number values obtained through numerical solutions of the obtained 2d problem by a finite difference method for different layer inclination angles,are in a good agreement with those predicted by the linear *** number of convective rolls realized in nonlinear calculations also fits the linear theory predictions for a given cavity *** carried out at low supercriticalities show that a direct bifurcation takes *** increasing supercriticality,no transitions to other convective regimes are *** situation studied in this problem can be observed in oil-bearing rock formations under the influence of a geothermal temperature gradient,where the ensuing fluid convection can affect the distribution of oil throughout the layer.

关键词： Thermal convection inclined layer porous media vertical temperature gradient

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Elucidating elusive quaternary selenide EuCeCuSe3:Synthesis,crystal structure,properties and theoretical studies

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Journal of Rare Earths 2024年第1期42卷 163-171,I0006页

作者： Maxim V.Grigoriev Anna V.Ruseikina Maxim S.Molokeev Vladimir A.Chernyshev Aleksandr S.Aleksandrovsky Alexander S.Krylov Svetlana N.Krylova Nikolai P.Shestakov dmitriy A.Velikanov Alexander A.Garmonov Alexey V.Matigorov evgeny A.Ostapchuk Thomas Schleid damir A.Safin Laboratory of Theory and Optimization of Chemical and Technological Processes University of TyumenVolodarskogo Str.6625003TyumenRussian Federation Kirensky Institute of Physics Federal Research Center KSC SB RASAkademgorodok 50 Bld.38660036KrasnoyarskRussian Federation department of Physics Far Eastern State Transport UniversitySerysheva Str.47680021KrasnoyarskRussian Federation Institute of Natural Sciences and Mathematics Ural Federal University Named After the First President of Russia B.N.YeltsinMira Str.19620002EkaterinburgRussian Federation department of Photonics and Laser Technology Siberian Federal UniversitySvobodnii Ave.79660079KrasnoyarskRussian Federation Institute of Physics and Technology University of TyumenVolodarskogo Str.6625003 TyumenRussian Federation Institute for Inorganic Chemistry University of StuttgartPfaffenwaldring 55D-70569StuttgartGermany Scientific and Educational and Innovation Center for Chemical and Pharmaceutical Technologies Ural Federal University named after the First President of Russia B.N.YeltsinMira Str.19620002 EkaterinburgRussian Federation University of Tyumen Volodarskogo Str.6625003TyumenRussian Federation

We report on the novel heterometallic quaternary selenide EuCeCuSe3,the fabrication of which has been a challenge until this *** structure of the reported selenide was elucidated from the powder X-ray diffraction data,which revealed the formation of EuCeCuSe3with excellent yield(96.7%)accompanied with a minor fraction of CeSe2(3.3%),and was best solved in orthorhombic space group Pnma with the BaLaCuS3structural ***,the crystal structure of the title compound completes the row of the heterometallic quaternary selenides EuRECuSe3(RE=La,Pr,Nd,Sm,Eu,Gd,Tb,dy,Ho,Er,Tm,Yb,Lu,Y),of which the cerium-based derivative exclusively belongs to the BaLaCuS3structural *** distortion of the CuSe4polyhedron was compared for the whole series of EuRECuSe3compounds using theτ4-descriptor for four coordinated ions,which revealed the highest degree of distortion for the Ce3+-containing selenide,followed by the La3+-based ***,the crystallographic and geometrical parameters of the reported selenide were discussed in comparison to the Ce3+-based sulfides SrCeCuS3and *** initio calculations of the crystal structure,a phonon spectrum and elastic constants for the crystal of EuCeCuSe3were also *** types and wavenumbers of fundame ntal modes were determined and the involvement of ions participating in the phonon modes was *** experimental IR spectrum of the reported selenide was interpreted and found to be in agreement with the calculated *** experimental direct band gap of EuCeCuSe3was measured to be 1.36 eV that is consistent with the concept of its origin due to interband transitions between orbitals emerging mainly from 4f(valence band)and 5d(conduction band)levels of the Eu2+*** dependence of the Young’s modulus on the direction demonstrates the anisotropy of the elastic properties,while the Vickers hardness for EuCeCuSe3was calculated to be 5.2 ***,the title compound is paramagnetic above 4 K.

关键词： Quaternary selenide Synthesis Crystal structure Ab initio calculations Magnetic measurements Spectroscopy

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device-based neuromodulation for cardiovascular diseases and patient’s age

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Journal of Geriatric Cardiology 2022年第11期19卷 876-893页

作者： evgeny N Mikhaylov Nigar Z Gasimova Natalia N Belyaeva Heber Ivan Condori Leandro Aleksandr d Vakhrushev evgeny V Shlyakhto Almazov National Medical Research Centre Saint-PetersburgRussia

The autonomic nervous system plays an important role in the pathogenesis of cardiovascular *** aging,autonomic activity changes,and this impacts the physiological reactions to internal and external *** sympathetic and parasympathetic responses seem to decline,reflecting functional and structural changes in nervous *** some investigators suggested that both the sympathetic and parasympathetic activities were suppressed,others found that only the parasympathetic activity was suppressed while the sympathetic activity *** addition,cardiac innervation progressively diminishes with ***,one may suggest that neuromodulation interventions may have different effects,and older age groups can express an attenuated *** article aims to discuss the effect of device-based neuromodulation in different cardiovascular diseases,depending on the patient’s ***,we cover renal denervation,pulmonary artery denervation,baroreceptor activation therapy,vagus nerve stimulation,spinal cord stimulation,ganglionated plexi ablation for the management of arterial and pulmonary hypertension,heart failure,angina and *** results of many clinical studies appeared to be *** view of the low rate of positive findings in clinical studies incorporating neuromodulation approaches,we suggest the underestimation of advanced age as a potential contributing factor to poorer *** of outcomes between different age groups in clinical trials may shed more light on the true effects of neuromodulation when neutral/ambiguous results are obtained.

关键词： stimulation cardiovascular diseases

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Predictive modelling of ferroelectric tunnel junctions

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npj Computational Materials 2016年第1期2卷 150-162页

作者： Julian P Velev John d Burton Mikhail Ye Zhuravlev evgeny Y Tsymbal department of Physics and Astronomy University of NebraskaLincolnNEUSA department of Physics and Astronomy University of Puerto RicoSan JuanPuerto RicoUSA Nebraska Center for Materials and Nanoscience University of NebraskaLincolnNEUSA Kurnakov Institute for General and Inorganic Chemistry Russian Academy of SciencesMoscowRussia Faculty of Liberal Arts and Sciences St Petersburg State UniversitySt PetersburgRussia

Ferroelectric tunnel junctions combine the phenomena of quantum-mechanical tunnelling and switchable spontaneous polarisation of a nanometre-thick ferroelectric film into novel device *** the ferroelectric barrier polarisation direction produces a sizable change in resistance of the junction—a phenomenon known as the tunnelling electroresistance *** a fundamental perspective,ferroelectric tunnel junctions and their version with ferromagnetic electrodes,i.e.,multiferroic tunnel junctions,are testbeds for studying the underlying mechanisms of tunnelling electroresistance as well as the interplay between electric and magnetic degrees of freedom and their effect on *** a practical perspective,ferroelectric tunnel junctions hold promise for disruptive device *** a very short time,they have traversed the path from basic model predictions to prototypes for novel non-volatile ferroelectric random access memories with non-destructive *** remarkable progress is to a large extent driven by a productive cycle of predictive modelling and innovative experimental *** this review article,we outline the development of the ferroelectric tunnel junction concept and the role of theoretical modelling in guiding experimental *** discuss a wide range of physical phenomena that control the functional properties of ferroelectric tunnel junctions and summarise the state-of-the-art achievements in the field.

关键词： ferroelectric tunnel resistance

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Reversal of the magnetoelectric effect at a ferromagnetic metal/ferroelectric interface induced by metal oxidation

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npj Computational Materials 2021年第1期7卷 1890-1896页

作者： Zhaojin Chen Qiong Yang Lingling Tao evgeny Y.Tsymbal School of Materials Science and Engineering Xiangtan UniversityXiangtanHunan 411105China department of Physics and Astronomy University of NebraskaLincolnNE 68588USA

Multiferroic materials composed of ferromagnetic and ferroelectric components are interesting for technological applications due to sizable magnetoelectric coupling allowing the control of magnetic properties by electric *** to being compatible with the silicon-based technology,HfO2-based ferroelectrics could serve as a promising component in the composite ***,a strong charge-mediated magnetoelectric coupling has been predicted for a Ni/HfO_(2) multiferroic ***,using density functional theory calculations,we systematically study the effects of the interfacial oxygen stoichiometry relevant to experiments on the magnetoelectric effect at the Ni/HfO_(2) *** demonstrate that the magnetoelectric effect is very sensitive to the interface stoichiometry and is reversed if an oxidized Ni monolayer is formed at the *** reversal of the magnetoelectric effect is driven by a strong Ni−O bonding producing exchange-split polarization-sensitive antibonding states at the Fermi *** argue that the predicted reversal of the magnetoelectric effect is typical for other 3d ferromagnetic metals,such as Co and Fe,where the metal-oxide antibonding states have an opposite spin polarization compared to that in the pristine ferromagnetic *** results provide an important insight into the mechanism of the interfacial magnetoelectric coupling,which is essential for the physics and application of multiferroic heterostructures.

关键词： ferromagnetic ferroelectric bonding

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In-plane ferroelectric tunnel junctions based on 2d α-In_(2)Se_(3)/ semiconductor heterostructures

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npj Computational Materials 2023年第1期9卷 2286-2292页

作者： Zifang Liu Pengfei Hou Lizhong Sun evgeny Y.Tsymbal Jie Jiang Qiong Yang Hunan Provincial Key Laboratory of Thin Film Materials and devices School of Materials Science and EngineeringXiangtan UniversityXiangtan 411105 HunanChina department of Physics and Astronomy University of NebraskaLincolnNE 68588USA

Ferroelectric tunnel junctions(FTJs)have great potential for application in high-density non-volatile ***,α-In_(2)Se_(3) was found to exhibit robust in-plane and out-of-plane ferroelectric polarizations at a monolayer thickness,which is ideal to serve as a ferroelectric component in miniaturized electronic *** this work,we design two-dimensional van der Waals heterostructures composed of anα-In_(2)Se_(3) ferroelectric and a hexagonal IV–VI semiconductor and propose an in-plane FTJ based on these *** first-principles calculations show that the electronic band structure of the designed heterostructures can be switched between insulating and metallic states by ferroelectric *** demonstrate that the in-plane FTJ exhibits two distinct transport regimes,tunneling and metallic,for OFF and ON states,respectively,leading to a giant tunneling electroresistance effect with the OFF/ON resistance ratio exceeding 1×*** results provide a promising approach for the high-density ferroelectric memory based on the 2d ferroelectric/semiconductor heterostructures.

关键词： ferroelectric plane tunneling

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Asymmetry ratio as a parameter of Eu^3＋ local environment in phosphors

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Journal of Rare Earths 2018年第5期36卷 474-481页

作者： Ilya E. Kolesnikov Alexey V. Povolotskiy daria V. Mamonova evgeny Yu. Kolesnikov Alexey V. Kurochkin Erkki Lahderanta Mikhail d. Mikhailov Saint Petersburg State University 7/9 Universitetskaya nab. 199034 St.petersburg.Russia Lappeenranta University of Technology LUT Skinnarilankatu 34 53850 Lappeenranta Finland Scientific and Technological Institute of Optical Material Science VNTs S. I. Vavilov State Optical Institute Babushkina 36-1 192171 St. Petersburg Russia Volga State University of Technology Lenin Sq. 3 424000 Yoshkar-Ola Russia

Study of the local environment of certain ion is quite a complex problem. due to the unique luminescent properties, Eu^3＋ ions can be used as a structural probe. In this paper, effect of doping concentration,excitation wavelength and excitation mechanism on asymmetry ratio was systematically studied using Y3Al5O12：Eu^3＋, YVO4：Eu^3＋ and Y2O3：Eu^3＋nanophosphors. The asymmetry ratio gives information about the local surrounding and environmental changes around the Eu^3＋ ions. Asymmetry ratios of YAG：Eu^3＋and YVO4：Eu^3＋ nanopowders were calculated using standard technique and the obtained average values were found to be 0.75 and 8.2, respectively. However, it is found that standard method of asymmetry ratio calculation is suitable only for samples where all Eu^3＋ ions occupy one site. The ＂multisite model＂ of asymmetry ratio calculation was developed and used for Y2O3：Eu^3＋ nanocrystalline powders. Average value of asymmetry ratio for Eu^3＋ ions occupied ＂normal＂ sites is 6.0 and for Eu^3＋ ions occupied ＂defect＂sites is 2.3.

关键词： Eu3+ Oxide powders Luminescence Asymmetry ratio Structural probe Rare earths

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Predicting the propensity for thermally activated β events in metallic glasses via interpretable machine learning

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npj Computational Materials 2020年第1期6卷 46-57页

作者： Qi Wang Jun ding Longfei Zhang evgeny Podryabinkin Alexander Shapeev Evan Ma department of Materials Science and Engineering Johns Hopkins UniversityBaltimoreMD 21218USA Center for Advancing Materials Performance from the Nanoscale(CAMP-Nano) State Key Laboratory for Mechanical Behavior of MaterialsXi’an Jiaotong UniversityXi’an 710049China department of Computer Science Johns Hopkins UniversityBaltimoreMD 21218USA Center for Energy Science and Technology Skolkovo Institute of Science and Technology3 Nobel StreetMoscow 143026Russia

The elementary excitations in metallic glasses(MGs),i.e.,β processes that involve hopping between nearby sub-basins,underlie many unusual properties of the amorphous alloys.A high-efficacy prediction of the propensity for those activated processes from solely the atomic positions,however,has remained a daunting ***,employing well-designed site environment descriptors and machine learning(ML),notable progress has been made in predicting the propensity for stress-activated β processes(i.e.,shear transformations)from the static structure.

关键词： structure glasses metallic

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Increased paracellular permeability of tumor-adjacent areas in 1,2-dimethylhydrazine-induced colon carcinogenesis in rats

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Cancer Biology & Medicine 2018年第3期15卷 251-259页

作者： Viktoria V.Bekusova evgeny L.Falchuk Larisa S.Okorokova Natalia M.Kruglova AlexANder d.Nozdrachev AlexANder G.Markov department of Physiology St.Petersburg State University I.P.Pavlov Institute of Physiology Russian Academy of Sciences

Objective: The morphology and functions of the proximal and distal large intestine are not the same. The incidence of colorectal cancer in these regions is also different, as tumors more often appear in the descending colon than in the ascending *** bowel disease and colorectal cancer can increase transepithelial permeability, which is a sign of reduced intestinal barrier function. However, there is not enough evidence to establish a connection between the difference in colorectal cancer incidence in the proximal and distal colon and intestinal permeability or the effects of carcinogenesis on the barrier properties in various areas of the colon. The aim of the study was to assess the permeability of different segments of the large intestine according to a developed mapping methodology in healthy rats and rats with 1,2-dimethylhydrazine(dMH)-induced colon ***: The short circuit current, the transepithelial electrical resistance and the paracellular permeability to fluorescein of large intestine wall of male Wistar rats were examined in the Ussing chambers. The optical density of the solution from the serosa side to assess the concentration of the diffused fluorescein from mucosa to serosa was analyzed by spectrophotometry. The morphometric and histological studies were performed by optical ***: Rats with dMH-induced colon adenocarcinomas showed elevated transepithelial electrical resistance in the areas of neoplasm development. In contrast, there was no change in the electrophysiological properties of tumor adjacent areas, however,the paracellular permeability of these areas to fluorescein was increased compared to the control rats and was characterized by sharply reduced barrier ***: The barrier properties of the colon vary depending on tumor location. The tumors were less permeable than the intact intestinal wall and probably have a negative influence on tumor-adjacent tissues by disrupting their bar

关键词： Rat 1,2-dimethylhydrazine colorectal cancer Ussing chamber short circuit current transepithelial electrical resistance intestinal permeability

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Numerical 3d-modeling of spall and shear fractures in shells of austenitic 12Kh18N10T steel and 30KhGSA steel under their spherical and quasi-spherical explosive loading

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International Journal of Modeling, Simulation, and Scientific Computing 2015年第1期6卷 173-211页

作者： evgeny A.Kozlov Oleg V.Ol’khov Ekaterina V.Shuvalova Russian Federal Nuclear Center–Zababakhin Research Institute of Technical Physics Snezhinsk Russia Russian Federal Nuclear Center–Research Institute of Experimental Physics Sarov Russia

To pursue VNIIEF–VNIITF joint investigations,this paper briefly describes the experimental setup and provides numerical 3d-computation results(LEGAK-3d technique)on special features in the convergence dynamics of steel shells under their quasi-spherical explosive loading in the system with the 40-mm outer radius of the explosive *** computation results were compared with the data experimentally registered for shells of the 30KhGSA steel,both as-received and quenched to HRC 35...40,and the austenitic 12Kh18N10T stainless *** comparison was also made with laserinterferometry results obtained directly under explosive loading,as well as with gammatomography and scanning electron microscopy investigations of the recovered shells.

关键词： Convergence dynamics of shell spall and shear damages explosive loading

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