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Upgradation of bauxite by molecular hydrogen and hydrogen plasma

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International Journal of Minerals,Metallurgy and Materials 2016年第10期23卷 1141-1149页

作者： B.R.Parhi s.K.sahoo s.c.mishra B.Bhoi R.K.Paramguru B.K.satapathy Department of Metallurgical and Materials Engineering National Institute of Technology Rourkela 769008 Odisha India Institute of Minerals and Materials Technology Bhubaneswar 751013 Odisha India Kalinga Institute of Industrial Technology Bhubaneswar 751024 Odisha India National Aluminium company Ltd. Bhubaneswar 751013 Odisha India

An approach was developed to upgrade the bauxite ore by molecular hydrogen and hydrogen plasma. A gibbsite-type bauxite sample was obtained from National Aluminium company（NALcO）, Odisha, India. The obtained sample was crushed and sieved（to 100 μm） prior to the chemical analysis and grain-size distribution study. The bauxite sample was calcined in the temperature range from 500 to 700°c for different time intervals to optimize the conditions for maximum moisture removal. This process was followed by the reduction of the calcined ore by molecular hydrogen and hydrogen plasma. Extraction of alumina from the reduced ore was carried out via acid leaching in chloride media for 2 h at 60°c. X-ray diffraction, scanning electron microscopy, thermogravimetry in conjunction with differential scanning calorimetry, and Fourier transform infrared spectroscopy were used to determine the physicochemical characteristics of the material before and after extraction. Alumina extracted from the reduced ore at the optimum calcination temperature of 700°c and the optimum calcination time of 4 h is found to be 90% pure.

关键词： upgrading bauxite calcination leaching alumina extraction

Anticonvulsant potential of rosuvastatin in combination with carbamazepine and valproate in animal models of epilepsy

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World Journal of Methodology 2025年第2期15卷 137-144页

作者： Vandana Tayal Akash Mandal Ijasul Haque M Akhilesh mishra Bhupinder s Kalra Vandana Roy Department of Pharmacology Maulana Azad Medical CollegeNew Delhi 110002India Department of Pharmacology MES Medical CollegePerintalmanna 679338KeralaIndia Department of central Animal Facility Maulana Azad Medical CollegeNew Delhi 110002India

BAcKGROUND Epilepsy impacts millions of people,with many not responding to existing *** evidence links neuroinflammatory processes to *** exhibit anti-inflammatory and neuroprotective properties,potentially offering antiepileptic *** To evaluate the anticonvulsant effects of rosuvastatin in animal models of *** Ninety-six albino mice were divided into 16 *** the maximal electroshock seizure(MEs)model,eight groups received intraperitoneal vehicle,carbama-zepine,rosuvastatin,or a *** measured included seizure protection[tonic hind limb extension(THLE)],duration of THLE,seizure duration,and *** the pentylenetetrazol(PTZ)model,eight groups were pretreated with vehicle,valproate,rosuvastatin,or a combination,with outcomes measured as seizure latency,seizure duration,and *** In the MEs model,rosuvastatin exhibited protection against THLE in a small percentage of *** shortens the duration of THLE in a dose-dependent ***,none of these were statistically significant com-pared to the control *** combination of rosuvastatin 10 mg/kg with carbamazepine 4 mg/kg resulted in a significant reduction in seizure duration compared to the control group,better than carbamazepine alone at 4 mg/kg and 6 mg/*** the PTZ model,rosuvastatin alone showed no significant effects on latency,duration of seizure,or ***,rosuvastatin 10 mg/kg combined with valproate 100 mg/kg significantly delayed the onset of seizures,seizure duration and mortality percentage,better than valproate alone at 100 mg/*** Rosuvastatin enhanced the anticonvulsant effects of carbamazepine and *** studies are required to explore the antiepileptic potential of rosuvastatin at various doses,durations,dosage forms,routes and models.

关键词： Antiepileptic Anticonvulsant statins Rosuvastatin Maximal electroshock seizure Pentylenetetrazol

Open charm mesons and charmonia in magnetized strange hadronic matter

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chinese Physics c 2022年第8期46卷 91-113页

作者： Amal Jahan c.s. Amruta mishra Department of Physics Indian Institute of TechnologyNew Delhi-110016India

We investigate the in-medium masses of open charm mesons(D(D^(0),D^(+)),■(■^(0),D^(-)),D_(s)(D_(s)^(+),D_(s)^(-)))and charmonium states(J/ψ,ψ(3686),ψ(3770),χ_(c0),χ_(c2)) in strongly magnetized isospin asymmetric strange hadronic matter using a chiral effective *** the presence of a magnetic field,the number and scalar densities of charged baryons have contributions from Landau energy *** mass modifications of open charm mesons result from their interactions with nucleons,hyperons,and the scalar fields(the non-strange field σ,strange field c and isovector field δ) in the presence of a magnetic *** mass modifications of the charmonium states result from the modification of gluon condensates in a medium simulated by the variation in the dilaton field(χ) in the chiral effective *** effects of finite quark masses are also incorporated in the trace of the energy-momentum tensor in quantum chromodynamics to investigate the mass shifts of charmonium *** in-medium masses of open charm mesons and charmonia are observed to decrease with an increase in baryon *** charged D^(+),D^(-),Z_(s)^(+),and D_(s)^(-)mesons have additional positive mass shifts due to Landau quantization in the presence of a magnetic *** effects of the strangeness fraction are observed to be more dominant for ■ mesons compared with D *** mass shifts of charmonia are observed to be larger in hyperonic media compared with nuclear media when the effect of the finite quark mass term is *** medium mass modifications can have observable consequences on the production of the open charm mesons and charmonia in high-energy asymmetric heavy-ion collision experiments.

关键词： open charm mesons charmonium states strange hadronic matter magnetic field heavy-ion collision chiral effective model

Effect of friction stir processing on mechanical properties and heat transfer of TIG welded joint of AA6061 and AA7075

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Defence Technology（防务技术） 2021年第3期17卷 715-727页

作者： Husain Mehdi R.s.mishra Department of Mechanical Engineering Delhi Technological UniversityDelhiIndia

Tungsten inert gas(TIG) welding is the most commonly used joining process for aluminum alloy for AA6061 and AA7075 which are highly demanded in the aerospace engineering and the automobile sector, but there are some defects occur during TIG welding like micro-crack, coarse grain structure, and porosity. To improve these defects, the TIG welded joint is processed using friction stir processing(FsP).This paper presents the effect of friction stir processing on TIG welding with filler ER4043 and ER 5356 for dissimilar aluminum alloy AA6061 and AA7075. The mechanical characterization, finite element formulation and mathematical equations of heat transfer of TIG + FsP welded joints are investigated using ANsYs Fluent software by adjusting process parameters of FsP. The results show that the maximum compressive residual stress 73 MPa was obtained at the fusion zone(FZ) of the TIG weldment with filler ER4043, whereas minimum compressive residual stress 37 MPa was obtained at stir zone(sZ) of the TIG+ FsP with filler 5356. The maximum heat flux 5.33 × 106 W/m2 and temperature 515c have observed at tool rotation 1600 rpm with a feed rate of 63 mm/min. These results give a satisfactory measure of confidence in the fidelity of the simulation。

关键词： Residual stress TIG+FsW Heat transfer Micro-hardness Tensile strength

MHD flow of a visco-elastic fluid through a porous medium between infinite parallel plates with time dependent suction

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Journal of Hydrodynamics 2015年第5期27卷 738-747页

作者： BAAG s. AcHARYA M.R. DAsH G.c. mishra s.R. Department of Physics College of Basic Science and HumanitiesOUAT Department of Mathematics ITER SOA University

This work provides a comprehensive theoretical analysis of MHD unsteady free convection viscoelastic fluid flow through a porous medium. The medium is treated as incompressible and optically transparent. The flow of the fluid is initiated by shearing action of the moving wall with time dependent suction. Radiative heat flow is considered in temperature equation. The coupled nonlinear problem has been solved asymptotically. Approximate solutions have been obtained for the mean velocity, mean temperature using multi parameter perturbation technique. The originality of the present study is to investigate the effect of viscoelastic property of the fluid（Walters B？ model） on the flow and heat transfer phenomena when the flow is permeated through a porous medium with uniform porous matrix subject to transverse magnetic field and time dependent fluctuative suction at the boundary surface. The case of viscous flow has been discussed as a particular case on comparison with the result reported earlier and it is in good agreement. Flow reversal is indicated incase of viscoelastic fluid with high heat capacity in the presence of magnetic field. The higher cooling of the plate in case of viscoelastic flow also causes a flow reversal.

关键词： viscoelastic liquid porosity radiation parameter time dependent suction

Dielectric, piezoelectric, and ferroelectric properties of lanthanum-modified PZTFN ceramics

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International Journal of Minerals,Metallurgy and Materials 2014年第10期21卷 1019-1027页

作者： Arvind Kumar s.K.mishra Research and Technology Development centre Sharda University Dr. Harisingh Gour University

specimens of Pb1-1.5xLax（Zr0.53 Ti0.47）1-y-zFeyNb2O3 （x = 0, 0.004, 0.008, 0.012, and 0.016, y = z = 0.01）（PZTFN） ceramics were synthesized by a semi-wet route. In the present study, the effect of La doping was investigated on the structural, microstructural, dielectric, piezoelectric, and ferroelectric properties of the ceramics. The results show that, the tetragonal （space group P4mm） and rhombohedral （space group R3c） phases are observed to coexist in the sample at x = 0.012. Microstructural investigations of all the samples reveal that La doping inhibits grain growth. Doping of La into PZTFN improves the dielectric, ferroelectric, and piezoelectric properties of the ceramics. The hys- teresis loops of all specimens exhibit nonlinear behavior. The dielectric, piezoelectric and ferroelectric properties show a maximum response atx 〉 0.012, which corresponds to the morphotropic phase boundary （MPB）.

关键词： ceramics lanthanum doping dielectric properties piezoelectricity ferroelectricity Rietveld refinement hysteresis loops

Nonsmooth semi-Infinite Minmax Programming Involving Generalized(Φ, ρ)-Invexity

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Journal of systems science & complexity 2015年第4期28卷 857-875页

作者： UPADHYAY B B mishra s K Department of Basic sciences & Humanities National Institute of Technology

This paper introduces some new generalizations of the concept of （~, p）-invexity for non- differentiable locally Lipschitz functions using the tools of clarke subdifferential. These functions are used to derive the necessary and sufficient optimality conditions for a class of nonsmooth semi-infinite minmax programming problems, where set of restrictions are indexed in a compact set. Utilizing the sufficient optimality conditions, the authors formulate three types of dual models and establish weak and strong duality results. The results of the paper extend and unify naturally some earlier results from the literature.

关键词： Duality, generalized invexity locally Lipschitz functions, minmax programming, semi-infinite programming.

Impedance and ferroelectric properties of sr^(2+) modified PZT-PMN ceramics

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International Journal of Minerals,Metallurgy and Materials 2014年第6期21卷 595-603页

作者： Arvind Kumar s.K.mishra Research and Technology Development centre Sharda University Dr. Harisingh Gour University

sr^2＋ modified polycrystalline PZT-PMN ceramics were synthesized by a semi-wet route. Impedance spectroscopy studies indicate the bulk and grain boundary effects of PZT-PMN material along with the negative temperature coefficient of resistance. The bulk conductiv-ity exhibits an Arrhenius-type thermally activated hopping process which is supported by the Ac conductivity behavior as a function of fre-quency and temperature. It is observed that the remnant polarization increases with an increase in the sr2＋content in PZT-PMN.

关键词： piezoelectric ceramics ferroelectric materials ferroelectricity electrochemical properties strontium

Effects of sr^(2+) substitution on the structural, dielectric, and piezoelectric properties of PZT-PMN ceramics

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International Journal of Minerals,Metallurgy and Materials 2014年第2期21卷 175-180页

作者： Arvind Kumar s.K. mishra Research and Technology Development centre Sharda University

This study described the structural, dielectric, and piezoelectric behavior of Pb1-xsrx[（Zr0.52Ti0.48）0.95（Mn1/3Nb2/3）0.05]O3 ceramics （PsZT-PMN, x=0, 0.025, 0.050, and 0.075）, prepared by a semi-wet route. X-ray diffraction, dielectric, and piezoelectric investigations were carried out to analyze the crystal structure. The relative dielectric constant and dielectric loss were both calculated as the functions of temperature. The room-temperature dielectric constant reaches a maximum for a sr2＋-modified PZT-PMN ceramic with an x value of 0.050, which corresponds to the morphotropic phase boundary （MPB）. Raman spectroscopy studies also confirm the existence of this MPB for x=0.050. The piezoelectric strain coefficients （d33） value shows a maximum response for this composition. In addition, the phase transition temperature decreases significantly when the sr2＋concentration increases in the PZT-PMN ceramics.

关键词： ceramic materials strontium substitution structural properties dielectric properties piezoelectricity