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Structural evolution, optoelectrical and corrosion properties of electrodeposited WO_3 integration on Zn-TiO_2 electrolyte for defence super application

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Defence Technology（防务技术） 2018年第5期14卷 396-402页

作者： A.A.Daniyan l.E.Umoru O.S.i.Fayomi A.p.i.popoola Department of Materials Science and Engineering Obafemi Awolowo University Department of Chemical Metallurgical and Materials Engineering Tshwane University of Technology Department of Mechanical Engineering Covenant University

Multifunctional nano composite coatings of Zn-TiO_2-WO_3 were deposited electrolytically on mild steel(MS) from Zn bath, having Zn^(2+) ions and uniform dispersion of TiO_2 and WO_3 nano particulates. The electrical, optical and corrosion resistance characteristics of the electrocodeposited coatings were assessed by Keithley 2400 Series Source meter with Multimeters, Newport Solar Simulator and a pGSTAT30 Autolab potentiostat respectively. The morphological characteristics of the composite coatings were characterized by scanning electron microscope(SEM) equipped with energy dispersive spectrometer(EDS). The result revealed that the electrocodeposits showed good stability and Zn-TiO_2-WO_3 nanocomposite deposits displayed enhanced microstructural qualities, good electrical conductivity and exhibited enriched corrosion resistance.

关键词： Nano-composite Electrocodeposition Corrosion Conductivity and resistance

Rietveld refinement and optical properties of SrWO_4:Eu^(3+) powders prepared by the non-hydrolytic sol-gel method

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Journal of Rare Earths 2015年第2期33卷 113-128页

作者： p.F.S.pereira i.C.Nogueira E.longo E.J.Nassar i.l.V.Rosa l.S.Cavalcante Chemistry institute University of the State of Sao Paulo Julio de Mesquita Filho-UNESP Francisco DegniAraraquara-SP 14800-900 Brazil liEC-Chemistry Department Federal University of Sao Carlos Via Washington Luis Km 235Sao Carlos-SP 13565-905 Brazil University of Franca-UNiFRAN Via Dr.Armando Sales de OliveiraNo.201 Franca-SP 14404-600 Brazil CCN-DQ-GERATEC University of the State of Piauí Joao Cabral 2231 P.O.Box 391Terezina PI 64002-150 Brazil

We investigated the effect of annealing time on the structure and optical properties of Sr WO4：Eu^3＋ powders prepared by the non-hydrolytic sol-gel method and heat treated at 800 ℃ for 2,4,8 and 16 *** and differential thermal analyses revealed that Sr WO4：Eu^3＋ powders were obtained at about 800 ℃.X-ray diffraction patterns and Rietveld refinement data confirmed that all powders had a scheelite-type tetragonal ***-Raman and Fourier transform infrared spectra indicated structural order at short range and anti-symmetric stretching vibrations of O-W-O bonds associated with tetrahedral[WO4]*** properties were investigated by ultraviolet-visible（UV-vis）diffuse reflectance,and photoluminescence（pl）data which provided the evolution of quantum efficiency（η）and lifetime（τ）.UV-vis spectroscopy evidenced intermediate energy levels within the band gap of Sr WO4：Eu^3＋ *** properties validated that the Eu^3＋ electric-dipole（^5D0→^7F2）transition in pl emission spectra was dominant which proved that Eu^3＋ ions were positioned in a site without an inversion center.[（^5D0→^7F2）/（^5D0→^7F1）]band ratios showed that Eu^3＋ ions were located in a low symmetry *** pl emission,ηandτproved the dependence on the annealing time in the behavior of Sr WO4：Eu3＋powders with a higher relative emission pl intensity as well as higherηandτvalues related to other samples when heat treated at 800℃ for 8 h.

关键词： SrWO4 Rietveld refinement optical band gap Eu^(3+) +-rare earth luminescence

The first detection of the solar U+Ⅲ association with an antenna prototype for the future lunar observatory

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Research in Astronomy and Astrophysics 2021年第8期21卷 16-22页

作者： l.A.Stanislavsky i.N.Bubnov A.A.Konovalenko p.l.Tokarsky S.N.Yerin institute of Radio Astronomy KharkivUkraine V.N.Karazin Kharkiv National University KharkivUkraine

We report about observations of solar U+Ⅲ bursts on 2020 June 5 by means of a new active antenna designed to receive radiation in 4–70 *** instrument can serve as a prototype of the ultralong-wavelength radio telescope for observations on the farside of the *** analysis of experimental data is based on simultaneous records obtained with the antenna arrays GURT and NDA in high frequency and time resolution,e-Callisto network as well as by using the space-based observatories STEREO and *** results from this observational study confirm the model of Reid and Kontar.

关键词： Sun:corona Sun:radio radiation methods:data analysis telescopes

Enhanced acetone sensing performance of nanostructured Sm2O3 doped SnO2 thick films

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Journal of Rare Earths 2017年第8期35卷 813-823页

作者： F.i.Shaikh l.p.Chikhale J.Y.patil i.S.Mulla S.S.Suryavanshi School of physical Sciences Solapur University Solapur 413255 (M.S.) lndia Council of Scientific and industrial Research Pashan Pune 411008 India

in the present work, we synthesized Sm2O3 doped SnO2 in order to prepare a selective acetone sensor with fast response, quick recovery and good repeatability. pure as well as 2 mol.%, 4 mol.%, 6 mol.% and 8 mol.% Sm2O3 doped SnO2 nanostructured samples were synthesized by using a co-precipitation method. The characterization of the samples was done by thermogravimetric and differential thermo-gravimetric analysis（TG-DTA）, X-ray diffraction（XRD）, field emission gun-scanning electron microscopy（FEG-SEM）, energy dispersive analysis by X-rays（EDAX）, high resolution scanning electron microscopy（HR-TEM）, selected area X-ray diffraction（SAED）, Brunauer-Emmet-Teller（BET） and ultraviolet-visible-near infrared（UV-Vis-NiR） spectroscopy techniques. The gas response studies of liquid petroleum gas, ammonia, ethanol and acetone vapor were carried out. The results showed that Sm doping systematically lowered operating temperature and enhanced the gas response and selectivity for acetone. The response and recovery time for 6 mol.% Sm2O3 doped SnO2 thick film at the operating temperature of 250 °C were 15 and 24 s, respectively.

关键词： tin oxide samarium oxide screen printing thick film acetone sensor rare earths

Exact solutions for magnetohydrodynamic nanofluids flow and heat transfer over a permeable axisymmetric radially stretching/shrinking sheet

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Chinese physics B 2024年第2期33卷 108-114页

作者： U.S.Mahabaleshwar G.p.Vanitha l.M.pérez Emad H.Aly i.pop Department of Studies in Mathematics Davangere UniversityShivagangothriDavangereIndia Departamento de F´ısica FACIUniversidad de Tarapac´aCasilla 7DAricaChile Department of Mathematics Faculty of EducationAin Shams UniversityRoxyCairoEgypt Department of Mathematics Babes-Bolyai University400084 Cluj-NapocaRomania

We report on the magnetohydrodynamic impact on the axisymmetric flow of Al_(2)O_(3)/Cu nanoparticles suspended in H_(2)O past a stretched/shrinked *** the use of partial differential equations and the corresponding thermophysical characteristics of nanoparticles,the physical flow process is *** resultant nonlinear system of partial differential equations is converted into a system of ordinary differential equations using the suitable similarity *** transformed differential equations are solved *** of the magnetic parameter,solid volume fraction and stretching/shrinking parameter on momentum and temperature distribution have been analyzed and interpreted *** skin friction and Nusselt number were also *** addition,existence of dual solution was deduced for the shrinking sheet and unique solution for the stretching ***,Al_(2)O_(3)/H_(2)O nanofluid flow has better thermal conductivity on comparing with Cu/H_(2)O ***,it was found that the first solutions of the stream are stable and physically realizable,whereas those of the second ones are unstable.

关键词： magnetohydrodynamic nanofluid stretching/shrinking sheet axisymmetric flow analytical solution suction/injection

Formation of a cerium conversion coating on magnesium alloy using ascorbic acid as *** and anticorrosive properties of the formed films

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Journal of Magnesium and Alloys 2016年第4期4卷 278-285页

作者： A.p.loperena i.l.lehr S.B.Saidman instituto de ingeniería Electroquímica y Corrosión(iNiEC) Departamento de Ingeniería QuímicaUniversidad Nacional del SurAv.Alem 12538000 Bahía BlancaArgentina

Cerium-based conversion coatings were formed on AZ91D magnesium alloy by immersion of the substrate in solutions containing Ce(NO_(3))_(3),H_(2)O_(2) and ascorbic acid(HAsc).The characterisation of the films was performed by electrochemical and surface analysis techniques such as SEM,EDS,X-ray diffraction and X-ray photoelectron spectroscopy(XpS).The degree of corrosion protection achieved was evaluated in simulated physiological solution by the open circuit potential monitoring,polarisation techniques and electrochemical impedance spectroscopy(EiS).The presence of HAsc in the conversion solution causes changes in the morphology,adherence and anticorrosive performance of the *** improvement in the corrosion resistance is closely associated with the corrosion inhibition properties of HAsc.

关键词： Cerium coatings AZ91D alloy Ascorbic acid Anticorrosive properties

Electrolytic deposition of super-smart composite coating of Zn-V2O5-NbO2 on low carbon steel for defence application

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Defence Technology（防务技术） 2018年第5期14卷 446-450页

作者： O.S.i.Fayomi l.R.Kanyane A.p.i.popoola S.O.Oyedepo Department of Chemical Metallurgical and Materials EngineeringTshwane University of TechnologyP.M.B.X680PretoriaSouth Africa Department of Mechanical Engineering Covenant UniversityP.M.B 1023OtaNigeria

Despite the massive usages of low carbon steel in automobile for engineering components, its corrosion and high friction coefficient in aggressive environment make it limited in service. This paper is aimed at modifying low carbon steel structural component with thin film composite for enhanced mechanical and corrosion properties. The steel structure was electrodeposited with Zn-V_2 O_5 and embedded with varied NbO_2 weight concentration of 6-12 wt % based electrolyte. Scanning electron microscope(SEM) and high optical microscope was used to study the microstructural evolution of the fabricated coatings. The thermal stability of the fabricated coatings was studied in an isothermal furnace at 300 ℃ and 600 ℃ and further characterized using a high tech optical microscope. potentiodynamic polarization technique was used to investigate the corrosion behavior of the composites in 3.65% NaCl. From the result, the effect of NbO_2 on Zn-V_2 O_5-NbO_2 was massive with improved crystal grain within the coatings lattices. The coating possesses strong metallurgical bonding and good corrosion resistance properties of about 0.315 mm/yr corrosion rate compare to 4.1 mm/yr of as-received sample. No doubt the impact of thermal shock on the resilient characteristics of the composite coating was moderate owing to the stable adherent properties of the deposited coatings.

关键词： Electrodeposition low carbon steel Micro-hardness Thermal stability corrosion behavior Rare earth metal(REM)

Soil carbon characterization along the profile of two forest soils under Quercus pyrenaica

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Journal of Forestry Research 2020年第2期31卷 591-600页

作者： A.p.Fernandez-Getino J.l.Alonso-prados M.i.Santin-Montanya UpF-DTEVpF Instituto Nacional de Investigacion y Tecnologia Agraria y AlimentariaINIACtra.A Corunakm 7.528040 MadridSpain Dpto.proteccion Vegetal Instituto Nacional de Investigacion y Tecnologia Agraria y AlimentariaINIACtra.A Corun akm 7.528040 MadridSpain

in light of concerns over climate change and increasing levels of CO2 in the atmosphere,it is of importance to investigate soil organic matter in Mediterranean forests at a profile ***-depth studies of the organic fraction are also of interest to improve understanding of carbon balance and to facilitate modelling of carbon fixation in forest *** research evaluates the relationships between diverse parameters such as colour,content,and form of soil organic matter(SOM).Two Quercus pyrenica ecosystems with soils classified as inceptisols with a xeric or dry moisture regime,and developed under a Mediterranean climate in Spain,were used to characterize SOM through the complete sequence of layers of the soil *** differentiating factor between the two ecosystems was slope *** was done using characteristics of humic substances(HS)as indicators of SOM turnover in *** analysis was used to further characterize the humic *** soil colour measurements are a tool for soil type classification and soil organic carbon prediction,the relation between HS colour measured by reflection and by transmission was determined in order to establish a relationship between measurement *** analysis and colour provided evidence of a different level of stabilization of HS from both soils,and between the different *** of humic acids was found to be greater in deeper horizons than in the surface *** inverse relationship between HS colour measured by reflection and by transmission was *** soils showed a clear trend in which horizons presenting lower absorbance numbers showed higher figures of hue and value.A more marked accumulation of humified compounds was found in pedons,(the smallest unit or volume of soil that contains all the soil types),in the less steep *** might be explained in terms of the physiographic position affecting infiltration behavior and exposure to runoff.

关键词： Organic matter turnover Colour humic substance(HS)by reflection Colour HS by transmission Humification index Mediterranean Quercus species

Extensions of 2-Homogeneous polynomials on c_0

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Acta Mathematica Sinica,English Series 2008年第5期24卷 877-880页

作者： pi-Kee liN Department of Mathematics University of MemphisMemphis TNUSA 38152

We prove that every 2-homogeneous polynomial on the complex co has a unique normpreserving extension to its bidual l∞.

关键词： Hahn-Banach extension homogeneous polynomial