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Transactions of Nonferrous Metals Society of China 2018年第8期28卷 1679-1686页

作者： o.l.rocha T.A.CoSTA M.DIAS A.GARCIA Federal hlstitute of Education Science and technology of Para - IFPA 66093-020 Belem-Para Brazil Faculty of mechanical Engineering Federal University of Para - UFPA 66075-110 Belem-Para Brazil Department of Manufacturing and Materials Engineering University of Campinas-UNICAMP 13083-860 Campinas-Sao Paulo Brazil

Horizontal directional solidification experiments were carried out with a monophasic Sn-2%Sb（mass fraction） alloy to analyze the influence of solidification thermal parameters on the morphology and length scale of the microstructure. Continuous temperature measurements were made during solidification at different positions along the length of the casting and these temperature data were used to determine solidification thermal parameters, including the growth rate（Vl） and the cooling rate（TR）. High cooling rate cells and dendrites are shown to characterize the microstructure in different regions of the casting, with a reverse dendrite-to-cell transition occurring for TR5.0 K/s. Cellular（λc） and primary dendrite arm spacings（λ1） are determined along the length of the directionally-solidified casting. Experimental growth laws relating λc and λ1 to Vl and TR are proposed, and a comparative analysis with results from a vertical upward directional solidification experiment is carried out. The influence of morphology and length scale of the microstructure on microhardness is also analyzed.

关键词： Sn-Sb monophasic alloy directional solidification thermal paIameters inicrostructure reverse cellular/dendritictransition

Effect of solidification process parameters on dry sliding wear behavior of AlNiBi alloy

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Transactions of Nonferrous Metals Society of China 2020年第3期30卷 582-594页

作者： T.M.BoTElHo H.M.AZEVEDo G.H.MACHADo C.R.BARBoSA F.S.rocha T.A.CoSTA o.l.rocha Federal Institute of Education Science and Technology of ParáIFPAAlmirante Barroso Avenue 115566093-020 BelémPABrazil Institute of Technology Federal University of ParáUFPAAugusto Correa Avenue 166075-110 BelémPABrazil

As-cast samples of the Al-3wt.%Ni-lwt.%Bi alloy resulting from the horizontal directional solidification process were subjected to the micro-abrasive wear *** effects of the solidification thermal and microstructural parameters,such as the growth and cooling rates and the cellular and primary dendritic spacings(Vl and TR;λ1 and λc;respectively),were evaluated in the wear resistance of the investigated *** tribological parameters analyzed were the wear volume and rate(Vw and Rw).The solidification experiments and the wear tests were carried out by means of a water-cooled horizontal directional solidification device and a rotary-fixed ball wear machine,*** results show lower Vw and Rw values correspond to finer microstructures and the Vw dependence on λ1 is characterized by an experimental mathematical equation.A better distribution of Bi soft droplets and Al3Ni hard intermetallic particles is observed within the finer interdendritic region and,in consequence,the better wear resistance is achieved in as-cast samples with dendritic morphology rather than cellular morphology.A transition of wear mechanism from adhesive to abrasive is observed.

关键词： unsteady-state horizontal solidification dry sliding wear cellular/dendrite arm spacing microhardness Bi particle Al_(3)Ni particle

Microstructural evolution during unsteady-state horizontal solidification of Al-Si-Mg(356) alloy

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Transactions of Nonferrous Metals Society of China 2018年第6期28卷 1073-1083页

作者： J.o.lIMA C.R.BARBoSA I.A.B.MAGNo J.M.NASCIMENTo A.S.BARRoS M.C.olIVEIRA F.A.SoUZA o.l.rocha Federal Institute of Education Science and Technology of Para IFPA 66093-220 Belem PA Brazil Federal University of Para Institute of Technology UFPA 66075-110 Belem PA Brazil

The increasing demand for reducing vehicle weight in the automotive and aerospace industries has raised the need to develop improved structural aluminum-based alloys. Thus, horizontal solidification experiment with the Al-7%Si-0.3%Mg（mass fraction） alloy was carried out. A water-cooled horizontal directional solidification device was developed and used. Microstructural characterization was carried out using traditional techniques of metallography, optical microscopy and SEM microscopy. The Thermo-Calc software was used to generate the solidification path of the investigated alloy with addition of 0.17% Fe（mass fraction）. The effects of the thermal parameters such as the growth rate（Vl）, cooling rate（TC） and solidification local time（tSl） on the formation of the macrostructure and on the dendritic microstructure evolution were evaluated. A columnar to equiaxed transition（CET） was found for Vl and TC values from 0.82 to 0.98 mm/s and from 1.71 to 2.55 ℃/s, respectively. The microstructure was characterized by the measurement of the primary and secondary dendrite arm spacings（λ1 and λ2, respectively）. Experimental laws of λ1 =f（Vl, TC） and λ2 =f（tSl） were proposed. It is observed that the interdendritic region is composed of the following eutectic mixture： a（Al）＋Si＋p-Al8 Mg3 Fe Si6＋q-Mg2 Si.

关键词： Al-Si-Mg alloy microstructural transition dendrite arm spacing transient heat flow

Investigation of the effects of radial clearance on the screw conveyor performances for different inclinations

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Particuology 2024年第9期92卷 72-80页

作者： Berna Bolat Birgül Aşçıoğlu Temiztaş Enes Sezer Department of Mechanical Engineering Yıldız Technical University34349BeşiktaşİstanbulTurkey

Screw conveyors are widely used for bulk material *** study investigates the critical role of radial clearance,the gap between the screw and the conveyor body,on performance across various inclination *** Discrete Element Method(DEM)is employed to analyze the effects of different radial clearances on conveyor performance for concrete aggregate and sand as bulk *** efficiencies and capacity losses serve as key performance indicators,quantitatively assessed for each radial clearance and inclination *** validation is conducted to corroborate the *** the study,the optimal radial clearance was identified as 1.5 to 3 times of the particle *** optimal clearance minimizes the material jamming and increases the performance for screw conveyors with different inclinations and bulk material types as a result.

关键词： Screw conveyors Radial clearance Discrete element method(DEM) Volumetric efficiency Conveyor performance

Rheological and stability analysis of cement pastes incorporating silica-based wastes

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Particuology 2024年第6期89卷 144-152页

作者： Julia da Rosa Martins Janaíde Cavalcante rocha Dachamir Hotza luciano Senff Graduate Program in Materials Science and Engineering(PPGMAT) Federal University of Santa Catarina(UFSC)Florianópolis88040-900SCBrazil Graduate Program in Civil Engineering(PPGEC) Federal University of Santa Catarina(UFSC)Florianópolis88040-900SCBrazil Graduate Program in Chemical Engineering(PoSENQ) Federal University of Santa Catarina(UFSC)Florianópolis88040-900SCBrazil Department of Mobility Engineering Federal University of Santa Catarina(UFSC)Joinville89219-600SCBrazil

This study investigates the influence of waste characteristics,especially zeta potential,on the properties of cement pastes and *** focus is to evaluate the impact of the zeta potential of cement particles and waste materials on the sedimentation speed,rheology,and hardening time of stabilized cement *** Cement II F 40,retarder additive,silica,and fly ash were used in the *** pastes were prepared,and during the stabilization period,their rheological properties and pH were *** zeta potential and sedimentation speed of the cement and waste particles were measured at the pH that the pastes presented during the entire stabilization *** the stabilization period,the pastes were subjected to the hardening time *** zeta potential analyses revealed diverse values for the different powder types,with the cement particles exhibiting a zeta potential of−3.0 mV,the silica particles exhibiting−10.5 mV,and the fly ash particles exhibiting−20.3 *** influence of the high zeta potential modulus was observed on the sedimentation speed,with the solution containing fly ash exhibiting a speed of 40.01μm/s,whereas the solution containing only cement exhibited a speed of 99.38μm/*** the pastes,the results indicate that the presence of fly ash particles with a significantly negative zeta potential led to a 16%reduction in hardening time compared to particles with a lower modulus of zeta *** tests showed that the inclusion of fly ash particles prevented the formation of *** the zeta potential influenced agglomerate formation and hardening time,it was found to have no effect on yield stress or viscosity.

关键词： Wastes Zeta potential Setting time Rheometry

Nickel sulfate solution fluoride separation with hydrous zirconium oxide

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Tungsten 2024年第2期6卷 367-381页

作者： Elbert M.Nigri Ummul K.Sultana André l.A.Santos James W.Vaughan Sonia D.F.rocha Department of Mining Engineering Federal University of Minas GeraisBelo Horizonte 31270-901Brazil School of Chemical Engineering University of QueenslandSt Lucia 4072Australia

Fluoride is an impurity in nickel sulfate production,which is required for electric vehicle *** zirconium oxide(HZo)was evaluated for removing fl uoride from nickel sulfate *** fluoride removal occurred at pH value 4 and optimal pH value is 4–5,considering Zr *** availability decreases with pH due to hydrogen fluoride and zirconium fluoride aqueous *** removal is initially rapid,with 50 wt.%removal in 7 min,followed by slow removal up to 68 wt.%after 72 h and follows second order rate *** removal was dominated by an ion exchange mechanism and resulting Zr–F bonds were observed using Fourier-transform infrared *** presence of nickel sulfate decreased loading capacity compared to a salt-free *** maintained adsorption capacity through five cycles of loading and regeneration.

关键词： Hydrous zirconium oxide Nickel sulfate Fluoride Adsorption Anion exchange

Black hole shadows in Einstein-Bel-Robinson gravity

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Chinese Physics C 2024年第5期48卷 272-283页

作者： B.Hamil B.C.lütfüoğlu laboratoire de Physique Mathématique et Subatomique Facultédes Sciences ExactesUniversitéConstantine 1ConstantineAlgeria Department of Physics University of Hradec KrálovéRokitanského 6250003 Hradec KrálovéCzechia

Gravity models given by higher-order scalar curvature corrections are believed to bear important consequences. Einstein-Bel-Robinson (EBR) gravity with quartic curvature modification motivated Sajadi et al. to explore static spherically symmetric black hole solutions using perturbative methods. In this study, inspired by their work, we investigate AdS black hole shadows in EBR gravity and demonstrate how the gravity parameter alters the energy emission rate. Finally, we address the same problem in the presence of plasma, because the black holes are thought to be surrounded by a medium that changes the geodesic of photons.

关键词： black hole shadows Einstein-Bel-Robinson gravity plasma

Effect of radiative loss mechanisms on FIR thermometric parameters of Nd^(3+)-doped lithium tellurite glasses

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Journal of Rare Earths 2024年第7期42卷 1250-1257,I0002页

作者： C.Y.Morassuti A.P.l Silva l.A.o.Nunes S.M.lima l.H.C.Andrade optical and Photothermal Spectroscopy Group(GEoF) Center for Studies in Natural Resources(CERNA)State University of Mato Grosso do Sul(UEMS)C.P.351DouradosMSBrazil Renato Archer Information Technology Center Dom Pedro I Highway(SP-65)Km 1436-Chácaras Campos dos AmaraisCampinasSPBrazil Institute of Physics of São Carlos University of São PauloSão CarlosSPBrazil

Nd^(3+)-doped tellurite glasses are promising materials for thermometers based on the fluorescence intensity ratio(FIR)***,at high Nd^(3+)concentrations,energy transfer(ET)processes such as optical reabsorption and cross-relaxation can affect the Nd^(3+)emission,which has been little explored in the ***,the present work investigated the use of Nd^(3+)-doped tellurite glass(samples doped with Nd^(3+)at 0.2 mol%,0.5 mol%,2.0 mol%,and 4.0 mol%)in fluorescence thermometers,in the temperature range from 299 to 371 *** results indicate a strong dependence of the FIR parameters on the Nd^(3+)concentration,due to changes in the emission band profiles caused by optical reabsorption of the Nd^(3+)emissions and cross-relaxation processes.A decrease of the relative sensitivity of the ratio^(4)F_(5/2)→^(4)I_(9/2)/^(4)F_(3/2)→^(4)I_(9/2)is observed for samples doped with higher amounts of Nd^(3+).The maximum relative sensitivity at 299 K is 3.00%/K,which is the highest value among the reported Nd^(3+)ions.

关键词： Nd^(3+)-doped tellurite glass Fluorescence intensity ratio optical thermometry Judd-ofelt Rare earths

Design,simulation,and testing of a tunable MEMS multi-threshold inertial switch

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Microsystems & Nanoengineering 2024年第2期10卷 37-46页

作者： Qiu Xu Rodrigo T.rocha Yousef Algoos Eric Feron Mohammad I.Younis Faculty of Electronic Information Engineering Huaiyin Institute of TechnologyHuai’an223003PR China Computer Electrical and Mathematical Science and Engineering DivisionKing Abdullah University of Science and TechnologyThuwal23955-6900Saudi Arabia Piezoelectric Microsystem Technologies Silicon Austria LabsVillach9524Austria Physical Sciences and Engineering Division King Abdullah University of Science and TechnologyThuwal23955Saudi Arabia Mechanical Engineering Department State University of New YorkBinghamtonNY13902USA

This paper presents a tunable multi-threshold micro-electromechanical inertial switch with adjustable threshold *** demonstrated device combines the advantages of accelerometers in providing quantitative acceleration measurements and g-threshold switches in saving power when in the inactive state upon experiencing acceleration below the *** designed proof-of-concept device with two thresholds consists of a cantilever microbeam and two stationary electrodes placed at different positions in the sensing *** adjustable threshold capability and the effect of the shock duration on the threshold acceleration are analytically investigated using a nonlinear beam *** are shown for the relationships among the applied bias voltage,the duration of shock impact,and the tunable *** fabricated prototypes are tested using a shock-table *** analytical results agree with the experimental *** designed device concept is very promising for the classification of the shock and impact loads in transportation and healthcare applications.

关键词： tunable acceleration testing

Inflammatory markers,oxidative stress,and mitochondrial dynamics:Repercussions on coronary artery disease in diabetes

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World Journal of Diabetes 2024年第9期15卷 1853-1857页

作者： JoséCarlos Tatmatsu-rocha luan Santos Mendes-Costa College of Medicine Postgraduate Program in Physiotherapy and FunctionalityFederal University of Ceará-UFCFortaleza 60430-450CearáBrazil Physical Therapy Federal University of CearáFortaleza 60000-000CearáBrazil

Inflammatory markers and mediators that affect the development of cardiovascular diseases have been the focus of recent scientific ***,the purpose of this editorial is to promote a critical debate about the article titled“Nε-carboxymethyl-lysine and inflammatory cytokines,markers,and mediators of coronary artery disease progression in diabetes”,published in the World Journal of Diabetes in *** work directs us to reflect on the role of advanced glycation end products,which are pro-inflammatory products arising from the metabolism of fatty acids and sugars whose main marker in tissues is Nε-carboxymethyllysine(NMl).Recent studies have linked high levels of pro-inflammatory agents with the development of coronary artery disease(CAD),especially tumor necrosis factor alpha,interleukins,and C-reactive *** inflammatory agents increase the production of reactive oxygen species(RoS),of which people with diabetes are known to have an increased *** increase in RoS promotes lipid peroxidation,which causes damage to myocytes,promoting myocardial ***,oxidative stress induces the binding of NMl to its receptor RAGE,which in turn activates the nuclear factor-kB,and consequently,inflammatory *** inflammatory cytokines induce endothelial dysfunction,with increased expression of adhesion molecules,changes in endothelial permeability and changes in the expression of nitric *** this sense,the therapeutic use of monoclonal antibodies(inflammatory reducers such as statins and sodium-glucose transport inhibitors)has demonstrated positive results in the regression of atherogenic plaques and consequently *** the other hand,many studies have demonstrated a relationship between mitochondrial dynamics,diabetes,and cardiovascular *** link occurs since RoS have their origin in the imbalance in glucose metabolism that occurs in the mitochondrial matrix,and this imbalance can have its origin in inadequate diet as well as

关键词： Mitochondrial dynamics Diabetes oxidative stress Coronary artery disease Nε-carboxymethyl-lysine