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Mechanism of reduction-diffusion reaction in Sm-Fe binary system at low temperature using molten salts

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Journal of Rare Earths 2024年第10期42卷 1889-1894页

作者： Jungryang Kim Shusuke Okada Kenta Takagi Kimihiro Ozaki Innovative Functional Materials Research institute National Institute of Advanced Industrial Science and Technology (AIST)

In this study,the mechanism of the reduction-diffusion reaction in a Sm-Fe binary system at low temperature was studied to investigate the possibility of synthesis of a Fe-rich TbCu7-type SmFex（x>9）by the low-temperature diffusion-reduction（LTRD） process using LiCl-KCl eutectic molten ***,the Sm-Fe phase transformation depending on the Sm-Fe composition,the LTRD temperature,and time was investigated,and it is found that the obtained metastable phase is only TbCu7-type SmFe～8.5,which is not a Fe-rich *** Fe content does not change even after an expended LTRD process,and the metastable TbCu7-type SmFe～8.5tends to transform to the stable *** addition,it is found that the Sm-Fe phase starts to synthesize from the Sm-rich phase in the order of SmFe2,SmFe3,and SmFe8.5as the LTRD temperature increases（when the time was 10 h） or the LTRD time increases（when the temperature was 550℃）.Core-shell-like particles are observed in the case of a short LTRD time,and the core and the shell are Fe and the Sm-rich Sm-Fe phase,respectively,indicating that the Sm-rich phase begins to produce on the surface of the Fe *** is difficult to synthesize a Fe-rich TbCu7-type SmFex（x>9） phase with the Sm-Fe binary system,suggesting that a different approach,such as addition of other elements,will be necessary.

关键词： Low-temperature synthesis Molten salts Rare earths Reduction-diffusion process Sm–Fe compounds Synthesis mechanism

Effect of distribution shape on the melting transition, local ordering,and dynamics in a model size-polydisperse two-dimensional fluid

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Chinese Physics B 2024年第7期33卷 419-428页

作者： Jackson Pame Lenin SShagolsem Department of Physics National Institute of Technology ManipurImphalIndia

We study the effect of particle size polydispersity(δ) on the melting transition(T*), local ordering, solid–liquid coexistence phase and dynamics of two-dimensional Lennard–Jones fluids up to moderate polydispersity by means of computer simulations. The particle sizes are drawn at random from the Gaussian(G) and uniform(U) distribution *** these systems, we further consider two different kinds of particles, viz., particles having the same mass irrespective of size, and in the other case the mass of the particle scales with its size. It is observed that with increasing polydispersity,the value of T*initially increases due to improved packing efficiency(φ) followed by a decrease and terminates at δ ≈8%(U-system) and 14%(G-system) with no significant difference for both mass types. The interesting observation is that the particular value at which φ drops suddenly coincides with the peak of the heat capacity(CP) curve, indicating a transition. The quantification of local particle ordering through the hexatic order parameter(Q_6), Voronoi construction and pair correlation function reveals that the ordering decreases with increasing δ and T. Furthermore, the solid–liquid coexistence region for the G-system is shown to be comparatively wider in the T –δ plane phase diagram than that for the U system. Finally, the study of dynamics reveals that polydisperse systems relax faster compared to monodisperse systems;however, no significant qualitative differences, depending on the distribution type and mass polydispersity, are observed.

关键词： polydispersity ordering phase diagram dynamics

Influence of variable viscosity and double diffusion on the convective stability of a nanofluid flow in an inclined porous channel

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Applied Mathematics and Mechanics(English Edition) 2024年第3期45卷 563-580页

作者： N.HUMNEKAR D.SRINIVASACHARYA Department of Mathematics National Institute of TechnologyWarangal 506004TelanganaIndia

The influence of variable viscosity and double diffusion on the convective stability of a nanofluid flow in an inclined porous channel is *** DarcyBrinkman model is used to characterize the fluid flow dynamics in porous *** analytical solutions are obtained for the unidirectional and completely developed *** on a normal mode analysis,the generalized eigenvalue problem under a perturbed state is *** eigenvalue problem is then solved by the spectral ***,the critical Rayleigh number with the corresponding wavenumber is evaluated at the assigned values of the other flow-governing *** results show that increasing the Darcy number,the Lewis number,the Dufour parameter,or the Soret parameter increases the stability of the system,whereas increasing the inclination angle of the channel destabilizes the ***,the flow is the most unstable when the channel is vertically oriented.

关键词： nanofluid inclined channel variable viscosity linear stability double dif-fusion porous medium

Geochemistry of volcanic glass from Mahanadi offshore region,eastern continental margin of India:Constraints on the contribution of latest Toba super-eruption

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Acta Oceanologica Sinica 2024年第2期43卷 111-119页

作者： Muralidhar Kocherla Durbar Ray Manavalan Satyanarayanan Hilda Joao Virsen Gaikwad PB Ramamurty CSIR-national institute of Oceanography Dona Paula 403004GoaIndia CSIR-national Geophysical Research institute Uppal RoadHyderabad 500007India

The tephra layers in multiple sediment cores from the offshore region of the Mahanadi basin in the northern Bay of Bengal were investigated for possible volcanic sources. The glass shards from those tephra layers were studied for size distribution, texture, and elemental geochemistry to establish chronostratigraphic markers for regional and global Quaternary correlation. The textural features of fine-grained(silty) volcanic glasses suggest the distal source of these tephra deposits. Major element composition with elevated SiO_(2) contents ranging between75%–76% and dominance of K_(2)O(> 4.5%) over CaO(< 0.9%) suggest ashes have originated from siliceous rhyolitic melts, similar to the petrographic composition of tephra from the Toba volcano. The bulk trace element compositions of the same glass shards were comparable with those reported in the youngest Toba tephra reported elsewhere. Likewise, the LREE-dominated chondrite normalized REE profiles of tephra from the Mahanadi basin closely resemble the characteristic REE patterns in Toba ash from other parts of the Indian Ocean and thus confirmed the contribution of the youngest Toba super-eruption for this ash layers.

关键词： Mahanadi basin Bay of Bengal volcanic glass glass morphology glass-chemistry

Electroluminescence from pure resonant states in hBN-based vertical tunneling junctions

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Light(Science & Applications) 2024年第8期13卷 1557-1564页

作者： Magdalena Grzeszczyk Kristina Vaklinova Kenji Watanabe Takashi Taniguchi Konstantin SNovoselov Maciej Koperski institute for Functional Intelligent Materials National University of SingaporeSingapore 117544Singapore Research Center for Functional Materials National Institute for Materials ScienceTsukuba 305-0044Japan International Center for Materials Nanoarchitectonics National Institute for Materials ScienceTsukuba 305-0044Japan Department of Materials Science and Engineering National University of SingaporeSingapore 117575Singapore

Defect centers in wide-band-gap crystals have garnered interest for their potential in applications among optoelectronic and sensor ***,defects embedded in highly insulating crystals,like diamond,silicon carbide,or aluminum oxide,have been notoriously difficult to excite electrically due to their large internal *** address this challenge,we realized a new paradigm of exciting defects in vertical tunneling junctions based on carbon centers in hexagonal boron nitride(hBN).The rational design of the devices via van der Waals technology enabled us to raise and control optical processes related to defect-to-band and intradefect *** fundamental understanding of the tunneling events was based on the transfer of the electronic wave function amplitude between resonant defect states in hBN to the metallic state in graphene,which leads to dramatic changes in the characteristics of electrons due to different band structures of constituent *** our devices,the decay of electrons via tunneling pathways competed with radiative recombination,resulting in an unprecedented degree of tuneability of carrier dynamics due to the significant sensitivity of the characteristic tunneling times on the thickness and structure of the *** enabled us to achieve a high-efficiency electrical excitation of intradefect transitions,exceeding by several orders of magnitude the efficiency of optical excitation in the sub-band-gap *** work represents a significant advancement towards a universal and scalable platform for electrically driven devices utilizing defect centers in wide-band-gap crystals with properties modulated via activation of different tunneling mechanisms at a level of device engineering.

关键词： carbide tunneling defect

Kinetics of dense plasma in the field of short laser pulses:A generalized approach

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Matter and Radiation at Extremes 2024年第5期9卷 87-92页

作者： V.A.Astapenko V.S.Lisitsa Moscow institute of Physics and Technology(national Research University) Institutskii per.9141701 DolgoprudnyiRussia national Research Centre“Kurchatov institute ”123182 MoscowRussia national Research Nuclear University MEPhI 115409 MoscowRussia

A generalized kinetic model of atomic level populations in an optically dense plasma excited by laser pulses of arbitrary duration is formulated and *** model is based on a nonstationary expression for the probability of excitation of an atomic transition and takes into account the effects of laser pulse penetration into an optically dense medium.A universal formula for the excitation probability as a function of time and propagation length is derived and applied to the case of a Lorentzian spectral profile of an atomic transition excited by a laser pulse with a Gaussian *** features of nonstationary excitation probabilities are presented for different optical depths of the plasma,laser pulse durations,and carrier *** formulas derived here will be useful for the description of atomic populations excited by laser pulses under realistic conditions of dense plasmas.

关键词： laser excitation excited

Extending microwave-frequency electric-field detection through single transmission peak method

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Chinese Physics B 2024年第5期33卷 417-423页

作者：刘青陈进湛王赫张杰阮伟民伍国柱郑顺元罗景庭宋振飞 College of Physics and Optoelectronic Engineering Shenzhen UniversityShenzhen 518060China Shenzhen institute for Technology Innovation National Institute of MetrologyShenzhen 518107China Center for Advanced Measurement Science National Institute of MetrologyBeijing 100029China

The strength of microwave(MW)electric field can be observed with high precision by using the standard electromagnetically induced transparency and Aulter–Towns(EIT-AT)technique,when its frequency is resonant or nearly-resonant with the Rydberg transition *** the detuning of MW field increases,one of the transmission peaks(single peak)is easier to measure due to its increased *** can be found that the central symmetry point of the two transmission peaks f_(1/2)is only related to the detuning of MW field△_(MW)and central symmetry point f_(0)of resonant MW field,satisfying the relation f_(1/2)=△_(MW)/2+f_(0).Thus,we demonstrate a single transmission peak method that the MW E-field can be determined by interval between the position of single peak and f_(1/2).We use this method to measure continuous frequencies in a band from-200 MHz to 200 MHz of the MW *** experimental results and theoretical analysis are presented to describe the effectiveness of this *** 50 MHz<△_(MW)<200 MHz,this method solves the problem that the AT splitting cannot be measured by using the standard EIT-AT techniques or multiple atomic-level Rydberg atom schemes.

关键词： microwave electric field Rydberg atom electromagnetically induced transparency(EIT) Aulter-Towns splitting

Heterogeneous crystallization of Chlorzoxazone for modulating the physicochemical properties of crystals Author links open overlay panel

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Particuology 2024年第8期91卷 249-259页

作者： Dhayananth Natarajan Kalaichelvi Ponnusamy Radhakrishnan Thota Karunakaran Department of Chemical Engineering National Institute of TechnologyTiruchirappalli620015TamilnaduIndia

The polymer on modulating the crystal's habit is an evolving research in pharmaceutical *** study demonstrates the crystal habit modification of chlorzoxazone(CHZ)by heterogeneous crystallization(HC)in the binary solvent acetonitrile-ethanol(A-E(1:1))in the presence of polyvinylpyrrolidine(PVP)at concentrations of 0.50,0.75,and 1.00 wt%.The A-E(1:1)and PVP in HC experiments influenced to change the shape of crystals from needle to plate shape and reduced the crystal size producing a lower aspect ratio(in the range of 1.5-2.3).In the presence of PVP,the CHZ size distribution is 65-78μm which tends to enhance the powder flow-ability of CHZ crystals and as the PVP concentration increases,the nucleation rate *** solubility of size-reduced CHZ crystals at different pH is found to be improved by 1.2-1.4 ***,HC is deemed effective in modifying the physicochemical attributes of CHZ.

关键词： Chlorzoxazone Polyvinylpyrrolidine Heterogeneous crystallization Crystal habit modification Aspect ratio

Callus proliferation-induced hypoxic microenvironment decreases shoot regeneration competence in Arabidopsis

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Molecular Plant 2024年第3期17卷 395-408页

作者： Dohee Koo Hong Gil Lee Soon Hyung Bae Kyounghee Lee Pil Joon Seo Department of Chemistry Seoul National UniversitySeoul 08826Korea Plant Genomics and Breeding institute Seoul National UniversitySeoul 08826Korea Research institute of Basic Sciences Seoul National UniversitySeoul 08826Korea

Plants are aerobic organisms that rely on molecular oxygen for respiratory energy *** conditions,with oxygen levels ranging between 1%and 5%,usually limit aerobic respiration and affect plant growth and ***,we demonstrate that the hypoxic microenvironment induced by active cell proliferation during the two-step plant regeneration process intrinsically represses the regener-ation competence of the callus in Arabidopsis *** showed that hypoxia-repressed plant regener-ation is mediated by the RELATED TO APETALA2.12(RAP2.12)protein,a memberof the Ethylene Response Factor VIl(ERF-Vll)*** found that the hypoxia-activated RAP2.12 protein promotes salicylic acid(SA)biosynthesis and defense responses,thereby inhibiting pluripotency acquisition and de novo shoot regeneration in *** and genetic analyses revealed that RAP2.12 could bind directly to the SALICYLIC ACID INDUCTION DEFICIENT 2(SID2)gene promoter and activate SA biosynthesis,repressing plant regeneration possibly via a PLETHORA(PLT)-dependent ***,the rap2.12 mutant calli exhibits enhanced shoot regeneration,which is impaired by SA *** together,these find-ings uncover that the cell proliferation-dependent hypoxic microenvironment reduces cellular pluripotency and plant regeneration through the RAP2.12-SID2 module.

关键词： callus cell proliferation-induced hypoxia SID2 plant regeneration salicylic acid RAP2.12