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Semi-oxalate synthesis of (1-x)BaTio3-xM0.5Bi0.5Tio3 (M =Li, Na, K)PTCR materials

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Journal of Advanced Ceramics 2016年第2期5卷 117-125页

作者： T.A.PLUTENKo o.i.V'YUNoV A.G.BELoUS o.Z.YANCHEVSKii Vernadskii institute of General and inorganic Chemistry of the Ukrainian NAS Prospect Palladina 32/34 Kyiv 142 03680 Ukraine

(1?x)BaTio3-xM0.5Bi0.5Tio3 (M = Li, Na, K) solid solutions were prepared using BaTio3 pre-synthesized by oxalate method. The stability limits of (1?x)BaTio3-xLi0.5Bi0.5Tio3 solid solutions have been established. it was shown that increase in M0.5Bi0.5Tio3 concentration results in reduction of ceramic grain size in the (1?x)BaTio3?xM0.5Bi0.5Tio3 (M = Li, Na, K) system. it was found that the positive temperature coefficient of resistance (PTCR) effect in lead-free materials is due to the presence of a semiconductor core, which is formed by sintering under reducing atmosphere, and dielectric grain boundaries, formed on additional oxidation in air. The use of barium titanate, pre-synthesized by oxalate method, in the synthesis of solid solutions reduced the sintering temperature of ceramics compared with solid state reaction technique. By comparing the electrical properties of the synthesized lead-containing and lead-free materials, it has been shown that lead-free materials exhibit better electrical properties for practical use compared with lead-containing materials.

关键词： lead-free ceramic BaTio3 semi-oxalate method positive temperature coefficient of resistance (PTCR) effect

High-Q surface electromagnetic wave resonance excitation in magnetophotonic crystals for supersensitive detection of weak light absorption in the near-infrared

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Photonics Research 2020年第1期8卷 57-64页

作者： o.V.BoRoVKoVA D.o.iGNATYEVA S.K.SEKATSKii A.KARABCHEVSKY V.i.BELoTELoV Russian Quantum Center SkolkovoMoscow 143025Russia Lomonosov Moscow State University Moscow 119991Russia Laboratoire de Physique de la Matiere Vivante IPHYSEPFL1015 LausanneSwitzerland School of Electrical and Computer Engineering Ben-Gurion University of the NegevBeer-Sheva 8410501Israel

The mid-infrared spectrum can be recorded from almost any material,making mid-infrared spectroscopy an extremely important and widely used sample characterization and analysis ***,sensitive photoconductive detectors operate primarily in the near-infrared(NiR),but not in the mid-infrared,making the NiR more favorable for accurate spectral *** the absorption cross section of vibrational modes in the NiR is orders of magnitude smaller compared to the fundamental vibrations in the mid-infrared,different concepts have been proposed to increase the detectability of weak molecular transitions ***,the contribution of magnetophotonic structures in the NiR absorption effect has never been explored so *** we propose high-Q magnetophotonic structures for a supersensitive detection of weak absorption resonances in the *** analyze the contributions of both magnetic and nonmagnetic photonic crystal configurations to the detection of weak molecular transitions *** results constitute an important step towards the development of highly sensitive spectroscopic tools based on high-Q magnetophotonic sensors.

关键词： absorption magneto resonance

Peculiarity of magnetoresistance of discontinuous ferromagnetic thin films

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international Journal of Minerals,Metallurgy and Materials 2017年第12期24卷 1459-1463页

作者： Yu.o. Shkurdoda i.M. Pazukha A.M. Chornous Department of Applied Physics Sumy State UniversitySumy 40007Ukraine

The magnetoresistive properties of discontinuous ferromagnetic Fe and Co thin films deposited by electron-beam sputtering onto glass substrates at room temperature were investigated. Tunnel magnetoresistance(MR) was observed for all of the as-deposited samples. The maximum MR was observed for Fe thin films with an effective thickness of 17 nm. in the case of the Co thin films, the annealing process led to a change of the type of MR to anisotropic at Co film thicknesses(dCo) of 15 ≤ d_(Co) ≤ 25 nm and to positive isotropic at thicknesses of d_(Co) ontrast, the MR type of Fe thin films did not change.

关键词： discontinuous thin films ferromagnetic structure magnetoresistance peculiarity

CFD evaluation of pressure drop across a 3-D filter housing for industrial gas turbine plants

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Frontiers in Energy 2016年第2期10卷 192-202页

作者： Fidelis i. ABAM Samuel o. EFFioM olayinka S. oHUNAKiN Department of Mechanical Engineering Michael Okpara University ofAgriculture Umudike Umuahia 02155 Nigeria Department of Mechanical Engineering Cross River University ofTechnology Calabar 540252 Nigeria Department of Mechanical Engneering Covenant Universiy Ota 11 O01Nigeria

This paper investigated the flow distribution and total pressure drop across a designed 3-D filter housing integrated with a 3-stage filtration system using computa- tional fluid dynamics （CFD）. The filter housing model was proposed for a heavy-duty industrial gas turbine plant operating at an average ambient temperature of 20℃.The pressure drops across the classes of filters were 652.8 Pa, 2692.2 Pa, 887.8 Pa, 776.2 Pa and 2304.2 Pa for i-GB, GB-GA, GA-FA, FA-HA, and HA-o, respectively. The results obtained indicated an acceptable total pressure drop of 7.2% for the entire filter housing before filter clean-up. Although the CFD simulation result shows that small outlet flow velocity and transonic flows exist at the outlet of the filter housing, the designed filter housing was proved compatible with the studied GT, for inlet flow conditions between 600≤ Wair≤610 kg/s and 60≤Vair≤70 m/s for the air flow rate and velocity, respectively. Furthermore, the designed filter housing could be adopted for the studied GT and locations of Usan and Maiduguri in Nigeria, and other locations with similar environmental conditions.

关键词： computational fluid dynamics (CFD) pressure drop flow distribution filter housing gas turbine

Measurement of mass attenuation coefficients,effective atomic numbers,and electron densities for different parts of medicinal aromatic plants in low-energy region

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Nuclear Science and Techniques 2018年第10期29卷 200-209页

作者： M.i.Sayyed F.Akman i.H.Geccbesler H.o.Tekin Department of Physics University of TabukTabuk 009662Saudi Arabia Department of Electronic Communication Technology Vocational School of Technical SciencesBingo¨l University12000 Bingo¨lTurkey Department of occupational Health and Safety Faculty of Health ScienceLaboratory of Natural Product ResearchBingo¨l University12000 Bingo¨lTurkey Department of Radiotherapy Uskdar University34662 I stanbulTurkey

The mass attenuation coefficients(l/q) for different parts(root, flower, stem, and leaf) of three medicinal aromatic plants(Teucrium chamaedrys L. subsp. sinuatum,Rheum ribes, and Chrysophthalmum montanum) were measured using an ^(241)Am photon source in a stable geometry and calculated using the Monte Carlo N-Particle Transport Code System-extended(MCNPX) code and the WinXCoM program. The experimental and theoretical MCNPX and WinXCoM values exhibited good *** measured mass attenuation coefficient values were then used to compute the effective atomic number(Z_(eff))and electron density(N_E) of the samples. The results reveal that S1-S(stem of Teucrium chamaedrys L. subsp. sinuatum) has the highest values of l/q and Zeff.

关键词： Medicinal Aromatic plant MCNPX code Mass attenuation coefficient Photon WinXCoM

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

Systematic experimental study of the temperature dependence of viscosity and rheological behavior of water-based drilling fluids with nano-additives

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Petroleum 2023年第4期9卷 534-544页

作者： A.V.Minakov M.i.Pryazhnikov E.i.Mikhienkova Y.o.Voronenkova Siberian Federal University KrasnoyarskRussia Kutateladze institute of Thermophysics SB RASNovosibirskRussia

The paper presents the results of a systematic study of the influence of nano-additives of various concentrations,average sizes and composition on the temperature dependence of the viscosity and rheological behavior of water-based drilling *** compositions of drilling fluids,such as water suspensions of various clay solutions and gammaxan-based polymer solutions,were *** nanoparticles of silicon and aluminum oxides were used as nano-additives at concentrations ranging from 0.25 to 3 wt%.The average nanoparticle size varied from 10 to 151 *** temperature of drilling fluids varied from 25℃ to 80℃.it is shown that the addition of nanoparticles to drilling fluids leads to a significant change in their rheological properties depending on the *** was found that with increasing temperature,the yield stress and consistency index of drilling fluids with nanoparticles increase,while the behavior index,on the contrary,*** behavior depends on the size of the *** the particle size increases,their influence on the temperature dependence of the drilling fluids’viscosity *** general,it is shown that the addition of nanoparticles makes the viscosity of drilling fluid more stable with regard to the *** is an essential fact for practical application.

关键词： Drilling fluid Nano-additive Viscosity Rheology Temperature

Seasonal variations and the influence of geomembrane liners on the levels of PBDEs in landfill leachates,sediment and groundwater in Gauteng Province,South Africa

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Emerging Contaminants 2017年第2期3卷 76-84页

作者： i.V.Sibiya o.i.olukunle o.J.okonkwo Tshwane University of Technology Department of EnvironmentalWater and Earth SciencesPrivate Bag X680PretoriaSouth Africa

in the present study,the seasonal concentrations of polybrominated diphenyl ethers(PBDEs)in leachate and sediment samples,and the influence of geomembrane liners on PBDE levels and the extent of their infiltration into groundwater on selected landfill sites in Gauteng Province,South Africa were *** and sediment samples were collected from seven operational landfill sites namely:Goudkoppies,Robinson Deep,Marie Louis,Soshanguve,onderstepoort,Hatherly and Garankuwa from Johannesburg and Pretoria,in winter and *** samples were collected from monitoring boreholes from two landfill ***-liquid and Soxhlet extraction techniques were employed for the extraction of leachate and groundwater,and sediment respectively using *** extracted samples were subjected to column clean up and,thereafter,analysed using gas chromatographyemass spectroscopy(GC-MS).PBDEs selected for the study were:BDE-17,-28,-47,-100,-99,-153,-154,-183 *** P9PBDE concentrations in leachate samples for winter and summer ranged from 0.316e1.36 ng L-1 and 0.560e1.08 ng L-1 *** P9 PBDE concentrations obtained for sediment in winter and summer were 3.00e4.91 ng g-1 and 2.50e3.71 ng g-1 *** samples exhibited higher(poncentrations for both leachate and sediment samples compared to summer *** trend was attributed to high precipitation rate in summer which may have infiltrated into the landfills,subsequently diluting the leachate and sediment *** contrast,the winter period is generally dry and PBDEs are,therefore,more likely to be *** concentrations of PBDEs in leachate and sediment samples were higher in landfill sites with geomembrane liners compared to those without *** samples taken from the vicinity of selected landfill sites without geomembrane liners exhibited high concentrations of P9PBDEs,indicating possible migration of PBDEs from landfill site into ***

关键词： Seasonal trend PBDEs concentrations Landfill leachates Sediment Groundwater Geomembrane liners

on a Subordination Result of a Subclass of Analytic Functions

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Advances in Pure Mathematics 2017年第11期7卷 641-646页

作者： Risikat ayodeji Bello Department of Mathematics and Statistics College of Pure and Applied Science Kwara State University Malete Nigeria

in this paper, we investigate a subordination property and the coefficient inequality for the class M(1, b), The lower bound is also provided for the real part of functions belonging to the class M(1, b).

关键词： Analytic Function Univalent Function Hadamard Product Subordination