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Second-Harmonic Response in Magnetic Nodal-Line Semimetal Fe_(3)GeTe_(2)

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Chinese Physics Letters 2022年第9期39卷 62-66页

作者： v.D.esin A.A.Avakyants A.v.Timonina N.N.Kolesnikov e.v.Deviatov Institute of Solid State Physics of the Russian Academy of Sciences ChernogolovkaMoscow District2 Academician Ossipyan Str.142432Russia

We experimentally investigate second-harmonic transverse voltage response to ac electrical current for a magnetic nodal-line semimetal Fe_(3)GeTe_(2)(FGT).For zero magnetic field,the observed second-harmonic voltage behaves as a square of the longitudinal current,as it should be expected for nonlinear Hall *** magnetic field behavior is found to be sophisticated:while the first-harmonic response shows the known anomalous Hall hysteresis in FGT,the second-harmonic Hall voltage is characterized by the pronounced high-field hysteresis and flat(B-independent)region with curves touching at low *** high-field hysteresis strongly depends on the magnetic field sweep rate,so it reflects some slow relaxation *** the lowest rates,it is also accomplished by multiple crossing *** shape of the second-harmonic hysteresis is known for skyrmion spin textures in nonlinear *** skyrmions have been demonstrated for FGT by direct visualization techniques,we can connect the observed high-field relaxation with deformation of the skyrmion ***,the second-harmonic Hall voltage response can be regarded as a tool to detect spin textures in transport experiments.

关键词： harmonic relaxation hysteresis

Modular next generation fast-neutron detector for portal monitoring

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Nuclear Science and Techniques 2022年第1期33卷 140-148页

作者： e.Aboud S.Ahn G.v.Rogachev v.e.Johnson J.Bishop G.Christian e.Koshchiy C.e.Parker D.P.Scriven Cyclotron Institute Texas A&M UniversityCollege StationTX 77843USA Department of Physics and Astronomy Texas A&M UniversityCollege StationTX 77843USA Department of Statistics Texas A&M UniversityCollege StationTX 77843USA

Nuclear nonproliferation is of critical importance for global *** fissile materials including highly enriched uranium and weapons-grade plutonium are especially important to *** interrogation techniques may result in much better sensitivity but are difficult with conventional portal monitors that rely on detecting thermal ***,most conventional portal monitoring systems rely on ^(3)He,which has a finite and continually decreasing *** designing a highly segmented array of organic scintillators,we posit that we can accurately and quickly identify fissile materials,including weapons-grade plutonium and highly enriched uranium,being *** propose a new design for a fast-neutron detector that overcomes the limitations of the current generation of portal ***6 simulations have been performed in conjunction with the UMPBT statistical model to determine the sensitivity limitations of the proposed *** suggest that the proposed detector may be 10 times more efficient than current-generation thermal neutron detectors and may be able to positively identify a 81 mg 235U source in as little as 192 seconds utilizing active interrogation techniques.

关键词： Fast-neutron detection Portal monitoring Nonproliferation

MgCo2-D2 and MgCoNi-D2 systems synthesized at high pressures and interaction mechanism during the HDDR processing

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Progress in Natural Science:Materials International 2017年第1期27卷 74-80页

作者： Chubin Wan v.e.Antonov R.v.Denys v.I.Kulakov v.A.Yartys University of Science and Technology Beijing Institute for energy Technology Institute of Solid State Physics Russian Academy of Sciences HYSTORSYS AS Norwegian University of Science and Technology

MgCo2and MgNiCo crystallize with hexagonal Laves type intermetallic structures of the C14 type and do not form hydrides at ambient hydrogen pressures. However, applying high hydrogen pressures in the GPa range forces the hydrogen absorption and leads to the formation of multi-phase compositions, which contain approximately 2.5 atoms H per formula unit of MgCo2or MgNiCo and remain thermally stable under normal *** hydrogenation of MgCo2resulted in its decomposition to a ternary Mg2CoD5deuteride and metallic cobalt. Phase-structural transformations accompanying the vacuum desorption of deuterium in the temperature range of 27–500 °C were studied using in situ neutron powder diffraction. The investigation showed a complete recovery of the initial MgCo2intermetallic via a Hydrogenation-Disproportionation-Desorption-Recombination process. At 300°C, the Mg2CoD5deuteride first decomposed to elementary Mg and hexagonal Co. At 400°C, a MgCo phase was formed by interaction between Mg and Co. At the highest processing temperature of 500°C, a solid-state interaction of MgCo and Co resulted in the recovery of the initial *** interaction of MgNiCo with deuterium under the synthesis conditions of 2.8 GPa and 200 °C proceeded in a more complex way. A very stable ternary deuteride MgNi2D3was leached away while Co was separated in the form of Mg2CoD5and the remaining nickel formed a solid solution with Co with the approximate composition *** thermal desorption of deuterium from MgCo2D2.5and from MgNiCoD2.5has been studied by Thermal Desorption Spectroscopy with deuterium released into a closed volume. The observed effects nicely correlate with changes in the phase structural composition of the hydrides ***2is a new example of the hydrogen storage alloy, in which a successful HDDR processing results in the reversible formation of the initial intermetallic at much lower temperatures than in the equilibrium phase diagram of the Mg-Co system.

关键词： Intermetallics Hydrogen storage materials Neutron powder diffraction High pressure synthesis Phase-structural transformations Magnesium Cobalt Nickel

emission colour tuning in KLnF_(4):Yb^(3+),er^(3+)/Ho^(3+)phosphor

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Journal of Rare earths 2024年第1期42卷 57-65,I0002页

作者： Janani K Gayathri e vijayatha v Ramasubramanian S Thiyagarajan P Department of Science and Humanities Nehru Institute of TechnologyKaliapuramThirumalayampalayamCoimbatoreIndia Department of Sciences Amrita School of Physical SciencesAmrita Vishwa VidyapeethamCoimbatoreIndia Department of Physics Anna UniversityChennaiIndia

KLnF_(4):Yb^(3+),er^(3+)/Ho^(3+)(Ln=Y,Yb,Gd)phosphors were prepared by solid-state reaction *** each of the Yb^(3+)/er^(3+)and Yb^(3+)/Ho^(3+)co-doped phosphors independently,phase confirmation and morphological examination were accomplished using the X-ray diffraction technique and scanning electron microscope analysis.X-ray photoelectron spectroscopy analysis shows the charge state and existence of lanthanides and *** luminescence emissions of green and red colour were detected for the synthesized *** changes in the upconverted emission intensities and colour output pertaining to the change of the lanthanide host matrix along with dopants were investigated for the prepared *** the upconversion luminescence,erbium-doped samples exhibit a predominance of red emission while holmium-doped samples display a prevalence of green *** rare-earth er/Ho doped KYbF4shows strong red emission compared to other ***_(4):Yb,er/Ho exhibits relatively significant green upconve rsion emissions,while Yb,er-doped KGdF_(4)host displays a 10-fold increase in green/red emission ratio with an increase in the input power of 20-780 *** photoluminescence studies and decay curve analysis were carried out using Uv light excitation for the developed phosphors.A higher lifetime of 2.2 ms was measured for the downshifting red emission in the Ho doped KYbF_(4)*** study suggests a potential for colour tunability in the upconversion and downshifting emissions through host modifications to the fluoride phosphor.

关键词： Rare earths energy transfer upconversion Downshifting Colour coordinates

Thermal effects and evolution of the defect concentration based on shear modulus relaxation data in a Zr-based metallic glass

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Chinese Physics B 2020年第8期29卷 133-136页

作者： Qi Hao Ji-Chao Qiao e v Goncharova G v Afonin Min-Na Liu Yi-Ting Cheng v A Khonik School of Mechanics Civil Engineering and ArchitectureNorthwestern Polytechnical UniversityXi'an 710072China Department of General Physics Voronezh State Pedagogical UniversityLenin Street 86Voronezh 394043Russia

A relationship between thermal effects and relaxation of the high-frequency shear modulus upon heat treatment of bulk Zr48(Cu5/6Ag1/6)44Al8 metallic glass is *** relationship is attributed to the relaxation of a interstitial-type defect system frozen-in from the melt upon glass *** data show that thermal effects occurring on heating include heat release below the glass transition temperature,heat absorption above it and heat release caused by *** equation derived within the Interstitialcy theory can be used to calculate the shear modulus relaxation using the calorimetric *** obtained results are used to trace the defect concentration as functions of temperature and thermal prehistory.

关键词： shear modulus metallic glass structural relaxation interstitialcy theory

Main Directions and Recent Test Modeling Results of Lithium Capillary-Pore Systems as Plasma Facing Components

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Plasma Science and Technology 2004年第3期6卷 2291-2295页

作者： v.A.evtikhin I.e.Lyublinski A.v.vertkov e.A.Azizov S.v.Mirnov v.B.Lazarev S.M.Sotnikov v.M.Safronov A.S.Prokhorov v.M.Korzhavin FSUe "Red Star"-"Prana-Center" Co Moscow Russian FSUe TRINITI Troitsk Moscow region Russian Federation RF Ministry for Atomic energy Moscow

At present the most promising principal solution of the divertor problemappears to be the use of liquid metals and primarily of lithium Capillary-Pore Systems (CPS) as ofplasma facing materials. A solid CPS filled with liquid lithium will have a high resistance tosurface and volume damage because of neutron radiation effects, melting, splashing and thermalstress-induced cracking in steady state and during plasma transitions to provide the normaloperation of divertor target plates and first-wall protecting elements. These materials will not bethe sources of impurities inducing an increase of Z_(eff) and they will not be collected as dust inthe divertor area and in ducts. experiments with lithium CPS under simulating conditions of plasmadisruption on a hydrogen plasma accelerator MK-200 [~ (10 - 15) MJ/m^2, ~ 50 μs] have beenperformed. The formation of a shielding layer of lithium plasma and the high stability of thesesystems have been shown. The new lithium limiter tests on an up-graded T-11M tokamak (plasma currentup to 100 kA, pulse length ~0.3 s) have been performed. Sorption and desorption of plasma-forminggas, lithium emission into discharge, lithium erosion, deposited power of the limiter areinvestigated in these experiments. The first results of experiments are presented.

关键词： lithium divertor plasma facing material

PARAMeTRIC OPTIMIZING ANALYSIS OF UNSTeADY STRUCTUReS AND vISUALIZATION OF MULTIDIMeNSIONAL DATA

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International Journal of Modeling, Simulation, and Scientific Computing 2013年第S1期4卷 115-127页

作者： A.e.BONDARev v.A.GALAKTIONOv Computer Graphics Department Keldysh Institute for Applied Mathematics Russian Academy of Sciences Moscow 125047Russia

The paper presents an approach to fast approximate estimation of conditions for spacetime structures appearing in the *** approach is based on combination of optimization problem computation with methods of data visual *** visual presentation methods are applied for analysis of multidimensional array containing discrete result *** problem solution is implemented by parallel computation in a multitask *** some cases,the approach allows to obtain for control parameter of considered problem the sought-for approximate dependence on characteristic parameters in a quasi-analytical form.

关键词： Optimization visualization parallel computations.

Adsorption and photo-catalytic properties of layered lepidocrocite-like quasi-amorphous compounds based on modified potassium polytitanates

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Particuology 2014年第6期12卷 22-28页

作者： e.v.Tretyachenko A.v.Gorokhovsky G.Y.Yurkov F.S.Fedorov M.A.vikulova D.S.Kovaleva e.e.Orozaliev Department of Chemistry Saratov State Technical University

TiO2 compounds possess relatively high adsorption abilities and exhibit high photocatalytic activities that exhibit potential for the destruction of organic pollutants in natural and waste *** potassium polytitanates modified using transition metals and their oxides/hydroxides generate new nanomaterials that operate in the visible spectral *** study presents the synthesis and investigation of the structure,composition and photocatalytic activity of powdered nanoscale quasi-amorphous potassium polytitanates particles modified with iron,zinc,copper,cobalt and nickel sulfate in aqueous *** of the powders investigated in this work exhibit a high adsorption capacity for methylene blue dye（15-20mg/g） related to the welldeveloped surface of the layered potassium polytitanate *** transition metals and their oxides/hydroxides influences the electronic structure of the obtained systems.A high photocatalytic activity was observed for systems containing iron,zinc,nickel and their oxides/hydroxides in the ultraviolet and visible ranges.

关键词： Layered potassium titanate Chemical modification Heterostructured particles Photocatalytic activity Adsorption

Two Classes of New exact Solutions to （2＋1）-Dimensional Breaking Soliton equation

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Communications in Theoretical Physics 2005年第5X期44卷 807-809页

作者： PeNG Yan-Ze e.v. Krishnan Department of Mathematics Huazhong University of Science and Technology Wuhan 430074 China Department of Mathematics and Statistics Sultan Qaboos University P.O. Box 36 A1-Khod 123 Muscat Sultanate of Oman

The singular manifold method is used to obtain two general solutions to a (2+1)-dimensional breaking soliton equation, each of which contains two arbitrary functions. Then the new periodic wave solutions in terms of the Jacobi elliptic functions are generated from the general solutions. The long wave limit yields the new types of dromion and solitary structures.

关键词： (2+1)-dimensional breaking soliton equation exact solutions singular manitold method