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effects of manganese doping on magnetocaloric effect in Ge-rich Gd_5Ge_(2.05)Si_(1.95) alloy

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Journal of Rare earths 2012年第3期30卷 217-221页

作者： e.Yüzüak i.Dincer Y.elerman Department of engineering Physics Faculty of EngineeringAnkara University

The structure, magnetic and magnetocaloric properties of the Ge-rich Gd5Ge2.05-xSi1.95-xMn2x （x=0.01 and 0.03） alloys were investigated by scanning electron microscopy, X-ray powder diffraction, differential scanning calorimeter （DSC） and magne.i.a.ion measurements. The results of energy dispersive X-ray analysis （eDX） and X-ray diffraction analyses showed that the composition and crystal structure of the alloys were desired. DSC measurements were performed to determine the transformation temperatures for each alloy. Both alloys exhibited the first order phase transition around room temperature. The alloys showed an anti-ferromagnetic transition around 60 K. The isothermal magnetic entropy changes of the alloys were determined from the isothermal magne.i.a.ion measurements by using the Maxwell relation. The maximum values of isothermal magnetic entropy change of the Gd5Ge2.05-xSi1.95-xMn2x alloy with x=0.01 was found to be -12.1 and -19.8 J/（kg·K） using Maxwell equation around 268 K in applied fields of 2 and 5 T, respectively.

关键词： magnetocaloric effect entropy change magnetic materials rare earths

Magnetocaloric properties of the Gd_5Si_(2.05-x)Ge_(1.95-x)Mn_(2x) compounds

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Journal of Rare earths 2010年第3期28卷 477-480页

作者： e.Yüzüak i.Dincer Y.elerman Ankara University Faculty of EngineeringDepartment of Engineering Physics

The influence of the manganese-alloying on the structure and magnetocaloric properties of the Gd5Si2.05Ge1.95 compound was studied by X-ray powder diffraction and magne.i.a.ion *** Gd5Si2.05-xGe1.95-xMn2x(2x=0,0.03 and 0.08) compounds crystallized in the Gd5Si2Ge2-type monoclinic *** all X-ray powder diffraction patterns,a minor hexagonal Gd5Si3 phase was observed as a second *** increasing Mn content,the unit cell volume *** the compounds with x=0,0.03 and 0.08,the fi...

关键词： magnetic materials heat treatments intermetallics rare earths

experiments Design for Hardness Optimization of the Ni-Cr Alloy electrodeposited by Pulse Plating

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Acta Metallurgica Sinica(english Letters) 2013年第5期26卷 558-564页

作者： i.imanieh e.Youse.i.a.Dolati M.R.Mohammadi Department of Materials Science and engineering Sharif University of Technology

The hardness of the Ni-Cr alloy which is electrodeposited in chloride solution, is optimized by design of experiment method（central composite design）. Various parameters were evaluated in order to find significant factors in this process. Frequency, duty cycle, current density and temperature were selected as efective factors. Analyses of variance（ANOVA） were performed on the results of the designed experiments. The best model which can predict the hardness of the Ni-Cr alloy electrodeposits was found whereas the frequency and quadratic behaviour of the current density were the most significant model terms. Serious interaction of the current density with frequency and duty cycle also were found in this model. Finally the optimum conditions of the factors for obtaining the maximum hardness of the Ni-Cr alloy were found. Ni-Cr alloy with hardness 828 HV（electrodeposited with frequency 63 Hz, current density 1800 A/m2, duty cycle 75% and temperature 31℃ bath） were assessed as the optimum deposit. The deposit under the optimum condition was investigated by scanning electron microscopy（SeM）, eDX analysis, polarization method and microhardness.

关键词： Ni-Cr electrodeposition Hardness Optimization

Formation of Nanoscale intermetallic Phases in Ni Surface Layer at High intensity implantation of Al ions

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Journal of Materials Science & Technology 2004年第5期20卷 583-586页

作者： i.A.Bozhko S.V.Fortuna i.A.Kurzina i.B.Stepanov e.V.Kozlov Yu.P.Sharkeev Tomsk State University of Architecture & Building 2 Solyanaya pl.Tomsk 634003RussiaTomsk State University of Architecture & Building2 Solyanaya pl.Tomsk 634003RussiaTomsk State University of Architecture & Building2 Solyanaya pl.Tomsk 634003RussiaNuclear Physics InstituteTomsk Polytechnic University2a Lenin Str.Tomsk 634050RussiaTomsk State University of Architecture & Building2 Solyanaya pl.Tomsk 634003.RussiaInstitute of Strength Physics and Materials ScienceRussian Academy of Sciences2/1 Pr.AkademicheskiiTomsk 634021Russia

The results of experimental study of nanoscale intermetallic formation in surface layer of a metal target at ion implantation are presented. To increase the thickness of the ion implanted surface layer the high intensive ion implantation is used. Compared with the ordinary ion implantation, the high intensive ion implantation allows a much thicker modified surface layer. Pure polycrystalline nickel was chosen as a target. Nickel samples were irradiated with Al ions on the vacuum-arc ion beam and plasma flow source 'Raduga-5'. it was shown that at the high intensity ion implantation the fine dispersed particles of Ni3Ai, NiAl intermetallic compounds and solid solution Al in Ni are formed in the nickel surface layer of 200 nm and thicker. The formation of phases takes place in complete correspondence with the Ni-Ai phase diagram.

关键词： High intensive ion implantation ion-plasma source intermetallic nanophases

Heavy metal concentrations in soils and plants in the vicinity of Arufu lead-zinc mine, Middle Benue Trough, Nigeria

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Chinese Journal Of Geochemistry 2010年第2期29卷 167-174页

作者： Nganje T.N. Adamu C.i. Ukpong e.e. Department of Geology University of Calabar Formerly Department of Geology University of Calabar

This study focused on the influence of base metal mining on heavy metal levels in soils and plants in the vicinity of Arufu lead-zinc mine, Nigeria. Soil samples (0-15 cm depth) and plant samples were collected from cul-tivated farmlands in and around the mine, the unmineralized site and a nearby forest (the control site). The samples were analyzed for heavy metals (Fe, Zn, Mn, Cu, Pb, Cr and Cd) by Atomic Absorption Spectrophotometry (AAS). The physical properties of soils (pH and LOi) were also measured. Results showed that soils from cultivated farm-lands have neutral pH values (6.5-7.5), and low organic matter contents (evels of Zn, Pb and Cd in culti-vated soils were higher than the concentrations obtained from the control site. These heavy metals are most probably sourced from mining and agricultural activities in the study area. Heavy metal concentrations measured in plant parts decreased in the order of rice leaves>cassava tubers>peelings. in the same plant species, metal levels decreased in the order of Zn>Fe>Mn>Cu>Pb>Cr>Cd. Most heavy metals were found in plant parts at average concentrations normally observed in plants grown in uncontaminated soil, however, elevated concentrations of Pb and Cd were found in a few cassava samples close to the mine dump. A stepwise linear regression analysis identified soil metal contents, pH and LOi as some of the factors influencing soil-plant metal uptake.

关键词：土壤重金属含量土壤样品植物样本铅锌矿尼日利亚原子吸收光谱法线性回归分析 amp

environmental performance assessments of different methods of coal preparation for use in small-capacity boilers: experiment and theory

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international Journal of Coal Science & Technology 2023年第5期10卷 57-71页

作者： A.N.Kozlov e.P.Maysyuk i.Yu.ivanova Melentiev energy Systems institute of Siberian Branch of the Russian Academy of Sciences Irkutsk130Lermontov664033Russia

The purpose of this article is to receive environmental assessments of combustion of different types of coal fuel depending on the preparation(unscreened,size-graded,briquetted and heat-treated)in automated boilers and boilers with manual *** assessments were made on the basis of data obtained from experimental methods of coal preparation and calculated methods of determining the amount of pollutant and greenhouse gas emissions,as well as the mass of ash and slag *** main pollutants from coal combustion are calculated:particulate matter,benz(a)pyrene,nitrogen oxides,sulfur dioxide,carbon *** the greenhouse gases carbon dioxide is *** a result of conducted research it is shown that the simplest preliminary preparation(size-graded)of coal significantly improves combustion efficiency and environmental performance:emissions are reduced by 13%for hard coal and up to 20%for brown *** introduction of automated boil-ers with heat-treated coal in small boiler facilities allows to reduce emissions and ash and slag waste by 2-3 *** best environmental indicators correspond to heat-treated lignite,which is characterized by the absence of sulfur dioxide emissions.

关键词： Coal preparation Automated and hand-fed coal boilers environmental performance metrics

Processes underlying the laser photochromic effect in colloidal plasmonic nanoparticle aggregates

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Chinese Physics B 2020年第3期29卷 412-419页

作者： A e ershov V S Gerasimov i L isaev A P Gavrilyuk S V Karpov institute of Computational Modeling SB RAS 660036KrasnoyarskRussia Siberian Federal University Krasnoyarsk660041Russia Kirensky institute of Physics Federal Research Center KSC SB RAS660036KrasnoyarskRussia Siberian State University of Science and Technology Krasnoyarsk 660014Russia

We have studied the dynamic and static processes occurring in disordered multiparticle colloidal Ag aggregates with natural structure and affecting their plasmonic absorption spectra under pico-and nanosecond pulsed laser radiations, as well as the physical origin responsible for these processes. We have shown that depending on the duration of the laser pulse,the mechanisms of laser modification of such aggregates can be associated both with changes in the resonant properties of the particles due to their heating and melting(picosecond irradiation mode) and with the particle shifts in the resonant domains of the aggregates(nanosecond pulses) which depend on the wavelength, intensity, and polarization of the *** mechanisms result in formation of a narrow dip in the plasmonic absorption spectrum of the aggregates near the laser radiation wavelength and affect the shape and position of the dip. The effect of polydispersity of nanoparticle aggregates on laser photochromic reaction has been studied.

关键词： nanoparticle surface plasmon resonance photochromic process pulsed laser radiation

Microstructure and mechanical properties of new Mg-Zn-Y-Zr alloys with high castability and ignition resistance

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international Journal of Minerals,Metallurgy and Materials 2024年第12期31卷 2714-2726页

作者： T.A.Koltygina V.e.Bazhenov A.V.Koltygin A.S.Prosviryakov N.Y.Tabachkova i.i.Baranov A.A.Komissarov A.i.Bazlov National University of Science and Technology MiSiS Moscow 119049Russia A.M.Prokhorov General Physics institute Russian Academy of SciencesMoscow 119991Russia Moscow State University of Medicine and Dentistry Moscow 127473Russia

Complex studies of new Mg-Zn-Y-Zr system alloys have been carried *** content range for the formation of the two-phase structure MgSS(Mg solid solution)+LPSO(long-period stacking ordered)in alloys of the Mg-Zn-Y-Zr system was determined by thermodynamic *** effect of heat treatment regimes on microstructure,mechanical,and corrosion properties was *** fluidity,hot tearing tendency,and ignition temperature of the alloys were *** best combination of castability,mechanical,and corrosion properties was found for the Mg-2.4Zn-4Y-0.8Zr *** alloys studied are superior to their industrial counterparts in terms of technological properties,while maintain high corrosion and mechanical *** increased level of pro-perties is achieved by a suitable heat treatment regime that provides a complete transformation of the 18R to 14H modification of the LPSO phase.

关键词： metals and alloys liquid-solid reactions microstructure fluidity mechanical properties corrosion transmission electron mi-croscopy

NMS Flows on Three-Dimensional Manifolds with One Saddle Periodic Orbit

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Acta Mathematica Sinica,english Series 2004年第1期20卷 47-56页

作者： B.campos A.CORDeRO J.Martinez ALFARO P.ViNDeL Department Matemàtiques Universitat Jaume I.CastellóSpain Department Matemàtica Aplicada Universitat Politècnica de ValènciaSpain Department Matemàtica Aplicada Facultat MatemàtiquesUniversitat de ValènciaSpain

The simplest NMS flow is a polar flow formed by an attractive periodic orbit and a repulsive periodic orbit as limit sets. in this paper we show that the only orientable, simple, compact, 3-dimensional manifolds without boundary that admit an NMS flow with none or one saddle periodic orbit are lens spaces. We also see that when a fattened round handle is a connected sum of tori, the corresponding flow is also a trivial connected sum of flows.

关键词： NMS systems Links of periodic orbits Round handle decomposition Lens spaces