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dielectric behavior of CaCu_(3)Ti_(4)O_(12) electro-ceramic doped with La,Mn and Ni synthesized by modified citrate-gel route

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Journal of Advanced Ceramics 2013年第2期2卷 119-127页

作者： Laxman SINGH U.S.RAI Alok kumar RAI k.d.mandal department of Chemistry Centre of Advanced StudyFaculty of ScienceBanaras Hindu UniversityVaranasi 221005U.P.India department of Materials Science and Engineering Chonnam National University300 Yongbong-dongBukguGwangju 500-757Republic of Korea department of Applied Chemistry Indian Institute of TechnologyBanaras Hindu UniversityVaranasi 221005U.P.India

The effect of La^(3+),Mn^(2+)and Ni^(2+)doped calcium copper titanate,CaCu_(3)Ti_(4)O_(12)(CCTO),at higher concentrations(CR1 and CR2 with 5 mol%and 10 mol%,respectively),has been examined by semi-wet route at relatively lower *** semi-wet route employs citrate-nitrate gel chemical method using TiO_(2) solid powders.X-ray diffraction(XRd)analysis confirms the formation of single phase in the doped samples sintered at 900℃for 8 *** electron micrographs(SEM)show that the average grain size for CR2 is larger than that of CR1 *** energy dispersive X-ray spectroscopy(EdX)is used to study the percentage compositions of different ions present in both *** constant(εr)and dielectric loss(tanδ)values of CR1 are comparatively higher than those of CR2 ceramic at all measured frequencies and *** nature of temperature-dependent relaxation behavior of the ceramics is also studied by impedance,modulus spectroscopic analysis and confirms Maxwell-Wagner relaxation.

关键词： oxide materials chemical synthesis dielectric properties grain boundaries X-ray diffraction(XRd)

dIELECTRIC PROPERTIES OF ULTRAFINE Zn-dOPEd CaCu_(3)Ti_(4)O_(12) CERAMIC

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Journal of Advanced dielectrics 2012年第1期2卷 92-97页

作者： LAXMAN SINGH U.S.RAI k.d.mandal MAdHU YASHPAL department of Chemistry Banaras Hindu University Varanasi 221005U.P.India department of Applied Chemistry Institute of Technology Banaras Hindu UniversityVaranasi 221005U.P.India Electron Microscope Facility Department of Anatomy Institute of Medical ScienceBanaras Hindu University Varanasi 221005U.P.India

Ultrafine powder of CaCu_(2.80)Zn_(0.20)Ti_(4)O_(12)ceramic was prepared using a novel semi-wet ***/TG analysis of dry powder gives pre-information about formation offinal product around 800℃.The formation of single phase was confirmed by X-ray diffraction *** average particle size of sintered powder of the ceramic obtained from XRd and Transmission electron microscopy was found 59 nm and 102 nm,*** dispersive X-ray studies confirm the stoichiometry of the synthesized *** constant of the ceramic was found to be 2617 at room temperature at 1 kHz.

关键词： Oxide ceramic XRd EdX chemical synthesis dielectric properties

Impedance spectroscopic and dielectric properties of nanosized Y_(2/3)Cu_(3)Ti_(4)O_(12)ceramic

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Journal of Advanced dielectrics 2014年第4期4卷 24-31页

作者： Sunita Sharma Shiv Sundar Yadav M.m.Singh k.d.mandal department of Chemistry Indian Institute of Technology (Banaras Hindu University)Varanasi 221005Uttar PradeshIndia

Yttrium Copper Titanate(Y_(2/3)Cu_(3)Ti_(4)O_(12))nanoceramic is structurally analogous to CaCu_(3)Ti_(4)O_(12)(CCTO).X-ray diffraction(XRd)of Y_(2/3)Cu_(3)Ti_(4)O_(12)(YCTO)shows the presence of all normal peaks of *** micrograph exhibits the presence of bimodal grains of size ranging from 1–2*** field TEM image clearly displays nanocrystalline particle which is supported by presence of a few clear rings in the corresponding selected area electron diffraction(SAEd)*** exhibits a high value of dielectric constant("0?8434)at room temperature and 100 Hz frequency with characteristic relaxation *** and modulus studies revealed the presence of temperature-dependent Maxwell–Wagner type of relaxation in the ceramic.

关键词： Ceramic chemical synthesis dielectric grain boundary impedance spectroscopy.

Behavior of an indigenously fabricated transferred arc plasma furnace for smelting studies

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Plasma Science and Technology 2018年第3期20卷 136-145页

作者： A k mandal R k dISHWAR O P SINHA department of Metallurgical Engineering IIT(BHU)

The utilization of industrial solid waste for metal recovery requires high-temperature tools due to the presence of silica and alumina, which is reducible at high temperature. In a plasma arc furnace, transferred arc plasma furnace（TAP） can meet all requirements, but the disadvantage of this technology is the high cost. For performing experiments in the laboratory, the TAP was fabricated indigenously in a laboratory based on the different inputs provided in the literature for the furnace design and fabrication. The observed parameters such as arc length, energy consumption, graphite electrode consumption, noise level as well as lining erosion were characterized for this fabricated furnace. The nitrogen plasma increased by around 200 k（200 ℃） melt temperature and noise levels decreased by ~10 d B compared to a normal *** plasma offered 100 k（100 ℃） higher melt temperature with ~5 d B higher sound level than nitrogen plasma. Nitrogen plasma arc melting showed lower electrode and energy consumption than normal arc melting, whereas hydrogen plasma showed lower energy consumption and higher electrode consumption in comparison to nitrogen plasma. The higher plasma arc temperature resulted in a shorter meltdown time than normal arc with smoother arcing. Hydrogen plasma permitted more heats, reduced meltdown time, and lower energy consumption, but with increased graphite consumption and crucible wear. The present study showed that the fabricated arc plasma is better than the normal arc furnace with respect to temperature generation, energy consumption, and environmental friendliness. Therefore, it could be used effectively for smelting-reduction studies.

关键词： smelting transferred arc plasma furnace characterization hydrogen and nitrogen plasma hollow electrode graphite and magnesite lining

Gravastar in the framework of symmetric teleparallel gravity

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Chinese Physics C 2023年第5期47卷 221-231页

作者： Sneha Pradhan Sanjay mandal P.k.Sahoo department of Mathematics Birla Institute of Technology and Science-PilaniHyderabad CampusHyderabad 500078India

We present a novel gravastar model based on the Mazur-Mottola(2004)method with an isotropic matter distribution in f(Q)*** gravastar,which is a hypothesized substitute for a black hole,is built using the Mazur-Mottola *** approach allows us to define the gravastar as having three *** first one is an inner region with negative pressure;the next region is a thin shell that is made up of ultrarelativistic stiff fluid,and we studied the proper length,energy,entropy,and surface energy density for this ***,we demonstrated the possible stability of our suggested thin shell gravastar model through the graphical study of the surface *** exterior Schwarzschild geometry describes the outer region of the *** the context of f(Q)gravity,we discovered analytical solutions for the interior of gravastars that are free of any type of singularity and the event horizon.

关键词： gravastar modified gravity non-metricity kuchowicz metric potential

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Theoretical study of differential cross sections for the ionization of helium by fast proton impact

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Chinese Physics B 2024年第11期33卷 255-264页

作者： M Mondal B mandal T Mistry d Jana M Purkait department of Physics Ramakrishna Mission Residential CollegeNarendrapurKolkata-700103India

We present the angular distribution of the ejected electron for single ionization of He by fast proton impact.A fourbody formalism of the three-Coulomb wave is applied to calculate the triple differential cross sections at several impact energies in the scattering,perpendicular and azimuthal ***,the three-body formalism of three-Coulomb,two-Coulomb and first Born approximation models has also been used to study the many-body effect on electron emission and the validity of the *** the three-Coulomb wave model,the final state wave function incorporates distortion due to the three-body mutual Coulombic *** this formalism,we use an uncorrelated and correlated Born initial state,which consists of a plane wave for the incoming projectile times a two-electron bound state wavefunction of the helium atom representing the 1s2(1S)***,in the case of the three-body formalism,the initial state wavefunction consists of a long-range Coulomb distortion for the incoming projectile and one active electron of the He atom described by the Roothaan–Hartree–Fock *** structure with a single or two peaks with unequal intensity is observed in the angular distributions of the triple differential cross sections for the different kinematic *** addition,the influence of static electron correlations is investigated using different bound state wavefunctions for the ground state of the He *** the four-body formalism,the present computations are very fast by reducing a nine-dimensional integral to a two-dimensional real *** the simplicity and speed of the proposed quadrature,the comparison shows that the obtained results are in reasonable agreement with the experiment and are compatible with those of other theories.

关键词： ionization cross sections collision atoms ions

Effect of blast inside tunnel on surrounding soil mass,tunnel lining,and superstructure for varying shapes of tunnels

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Underground Space 2021年第6期6卷 619-635页

作者： M.d.Goel Shivani Verma Jagriti mandal Sandeep Panchal department of Applied Mechanics Visvesvaraya National Institute of Technology(VNIT)Nagpur 440010MaharashtraIndia department of Mining Engineering Visvesvaraya National Institute of Technology(VNIT)Nagpur 440010MaharashtraIndia

In this study,a finite element(FE)analysis of shallow tunnels exposed to a blast inside the tunnel,with soil as surrounding medium and a structure at ground level,was *** ConWep program,developed by the US Army,was used to simulate blast loading using ABAQUS/Explicit■.drucker-Prager(d-P)plasticity model,concrete damage plasticity(CdP),and Johnson-Cook(J-C)plasticity models were used to define the behavior of the soil,concrete,and reinforcement,*** analysis was carried out to compare the damages to the superstructure with variation in the cross-sectional shapes of the tunnel under internal blast *** tunnel shapes(circular,rectangular,and horseshoe cross-sections)were considered in the FE *** explosive of 100 kg TNT was located at the center of the cross-section of the *** response of the tunnel in terms of displacement and stress at critical locations was *** results showed that changes in the cross-section of the tunnel affect the stability of the tunnel,even when keeping all other factors *** was observed that the intensity of the stresses was the highest for a rectangular tunnel and lowest for a circular ***,it was also determined that the tunnel with a rectangular cross-section experienced the maximum displacement in the reinforced concrete(RC)lining compared with the horseshoe and circular *** displacement measured at critical structural members of the superstructure was found to be the highest for the tunnel with a rectangular cross-section and lowest for the tunnel with a circular cross-section.

关键词： Blast loading Numerical simulation ConWep Framed superstructure FE analysis ABAQUS/Explicit■

Biochemical dissection of STAT3 signaling in amyotrophic lateral sclerosis

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Neural Regeneration Research 2025年第11期20卷 3229-3230页

作者： Savina Apolloni Nadia d’Ambrosi department of Biology University of Rome Tor VergataRomeItaly

Amyotrophic lateral sclerosis(ALS)is a progressive neurodegenerative disease characterized by the loss of upper and lower motor neurons,clinically marked by muscle atrophy and *** the clinical course is highly variable,the average time from the onset of symptoms to the need for respiratory support or death is 3-5 *** is the most prevalent motor neuron disease in adults,occurring at a rate of 2 per 100,000 individuals and affecting 5.4 per 100,000 individuals overall.

关键词： STAT3 dissection sclerosis

Influence of in-flight particle state diagnostics on properties of plasma sprayed YSZ-CeO_(2) nanocomposite coatings

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International Journal of Smart and Nano Materials 2014年第3期5卷 207-216页

作者： S.Mantry B.B.Jha A.mandal d.k.Mishra B.k.Mishra M.Chakraborty CSIR-Institute of Minerals&Materials Technology Bhubaneswar 751013OdishaIndia School of Minerals Metallurgical and Materials EngineeringIndian Institute of Technology BhubaneswarBhubaneswar 751007OdishaIndia department of Physics Institute of Technical Education and ResearchSiksha‘O’Anusandhan UniversityKhandagiri SquareBhubaneswar 751030OdishaIndia department of Physics College of ScienceEngineering and TechnologyUniversity of South AfricaJohannesburgSouth Africa

This article describes the influence of controlling in-flight hot particle characteristics on properties of plasma sprayed nanostructured yttria stabilized zirconia(YSZ)*** article depicts dependence of adhesion strength of as-sprayed nanostructured YSZ coatings on particle temperature,velocity and size of the splat prior to impact on the metallic *** temperature measurement is based on two-color pyrometry and particle velocities are measured from the length of the particle traces during known exposure *** microstructure and adhesion strength of as-sprayed nano-YSZ coatings were *** emission scanning electron microscopy results revealed that morphology of coating exhibits bimodal microstructure consisting of nano-zones reinforced in the matrix of fully melted *** coating adhesion strength is noticed to be greatly affected by the melting state of *** adhesion strength of 42.39 MPa has been experimentally found out by selecting optimum levels of particle temperature and *** enhanced bond strength of nano-YSZ coating may be attributed to higher interfacial toughness due to cracks being interrupted by adherent nano-zones.

关键词： CeYSZ nano-zones spray diagnostics adhesion plasma spraying