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Journal of Rare Earths 2016年第4期34卷 420-427页

作者： R.Pérez-Bustamante A.Reyna-cruz D.c.Acosta-Pena c.R.Santillán-Rodríguez J.A.matutes-Aquino F.Pérez-Bustamante m.c.maldonado-orozco J.Aguilar-Santillán R.martínez-Sánchez Research center in Advanced materials(cImA V) National Laboratory of NanotechnologyMiguel de Cervantes No.120C.P.31109ChihuahuaChih.Mexico Faculty of Engineering Autonomous University of Chihuahua(UACH)Circuito No.1 Nuevo Campus UniversitarioC.P.31 125ChihuahuaChih.Mexico Faculty of chemical Sciences Autonomous University of Chihuahua(UACH)Circuito No.1 Nuevo Campus UniversitarioC.P.31125ChihuahuaChih.Mexico materials&Tools LLc 4118 E Washington CtGilbertAZUSA 85234

The effect of the Al-6ce-3La（AcL） on the microstructural behavior of the Al7075 was investigated. materials were synthesized by mechanical alloying with variation in the AcL content and milling time. Products were characterized and studied in the as-milled condition and mechanically evaluated after sintering. The synergetic effect of milling time and AcL content in the modified materials led to a reduction in the particle size. Results from electron microscopy showed a homogeneous dispersion of ce/La phases up to 20 wt.% of AcL content after 10 h of milling. mechanical evaluation under compressive test showed an improved performance for those alloys reinforced with 0.2 wt.% and 0.5 wt.% of AcL.

关键词： mechanical alloying rare earths aluminum microstructure sintering

Predicting grain size-dependent superplastic properties in friction stir processed ZK30 magnesium alloy with machine learning methods

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Journal of magnesium and Alloys 2024年第5期12卷 1931-1943页

作者： Farid Bahari-Sambran Fernando carreno c.m.cepeda-Jiménez Alberto orozco-caballero Physical metallurgy Department CENIM-CSICAv.Gregorio del Amo 828040 MadridSpain Department of mechanical Engineering Chemistry and Industrial DesignPolytechnic University of MadridRonda de Valencia 328012MadridSpain

The aim of this work is to predict,for the first time,the high temperature flow stress dependency with the grain size and the underlaid deformation mechanism using two machine learning models,random forest(RF)and artificial neural network(ANN).With that purpose,a ZK30 magnesium alloy was friction stir processed(FSP)using three different severe conditions to obtain fine grain microstructures(with average grain sizes between 2 and 3μm)prone to extensive superplastic *** three friction stir processed samples clearly deformed by grain boundary sliding(GBS)deformation mechanism at high *** maximum elongations to failure,well over 400% at high strain rate of 10^(-2)s^(-1),were reached at 400℃ in the material with coarsest grain size of 2.8μm,and at 300℃ for the finest grain size of 2μ***,the superplastic response decreased at 350℃ and 400℃ due to thermal instabilities and grain coarsening,which makes it difficult to assess the operative deformation mechanism at such *** work highlights that the machine learning models considered,especially the ANN model with higher accuracy in predicting flow stress values,allow determining adequately the superplastic creep behavior including other possible grain size scenarios.

关键词： machine learning Artificial intelligence magnesium alloys Superplasticity Friction stir processing Grain coarsening

Influence of the Accumulative Roll Bonding Process Severity on the microstructure and Superplastic Behaviour of 7075 Al Alloy

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Journal of materials Science & Technology 2016年第8期32卷 774-782页

作者： R Hidalgo-manrique A.orozco-caballero c.m.cepeda-Jimenez O.A.Ruano, F.carreno Department of Physical metallurgy CENIM CSIC Av. Gregorio del Amo 8 28040 Madrid Spain School of materials The University of ManchesterManchester M1 7SH UK. ImDEA materials Institute. c/Eric Kandel 2 28906 Getafe MadridSpain

The 7075 Al alloy was processed by accumulative roll bonding （ARB） at 350 ℃ using 2：1, 3：1 and 4：1 thickness reductions per pass （Rp） up to 8, 6 and 3 passes, respectively. microstructural examinations of the processed samples revealed that ARB leads to a microstructure composed of equiaxed crystallites with a mean size generally lower than 500 nm. It was found that, due to both the stored energy through- out the processing and the particle pinning effect, the alloy is affected by discontinuous recrystallisation during the inter-pass heating stages, the precise microstructural evolution being dependent on Rp. me- chanical testing of the ARBed samples revealed that the main active deformation mechanism in the ARBed samples in the temperature range from 250 to 350 ℃ at intermediate and high strain rates is grain bound- ary sliding, the superplastic properties being determined by both the microstructure after ARB and its thermal stability.

关键词： Accumulative roll bonding (ARB) Al-Zn-mg-cn alloys Grain refining Precipitate coarsening Recrystallisation Superplastic deformation

A renewal theory based performance and configuration framework of the IEEE 802.11ah RAW mechanism

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Digital communications and Networks 2023年第1期9卷 236-251页

作者： Hamid Taramit Luis orozco-Barbosa Abdelkrim Haqiq Hassan First University of Settat Faculty of Sciences and TechniquesComputerNetworksMobility and Modeling Laboratory:IR2M26000 SettatMorocco Albacete Research Institute of Informatics Universidad de Castilla-La Mancha02006 AlbaceteSpain

IEEE 802.11ah is a new Wi-Fi standard for sub-1Ghz communications,aiming to address the challenges of the Internet of Things(IoT).Significant changes in the legacy 802.11 standards have been proposed to improve the network performance in high contention scenarios,the most important of which is the Restricted Access Window(RAW)*** mechanism promises to increase the throughput and energy efficiency by dividing stations into different *** this scheme,only the stations belonging to the same group may access the channel,which reduces the collision probability in dense ***,the standard does not define the RAW grouping *** this paper,we develop a new mathematical model based on the renewal theory,which allows for tracking the number of transmissions within the limited RAW slot contention period defined by the *** then analyze and evaluate the performance of RAW *** also introduce a grouping scheme to organize the stations and channel access time into different groups within the ***,we propose an algorithm to derive the RAW configuration parameters of a throughput maximizing grouping *** additionally explore the impact of channel errors on the contention within the time-limited RAW slot and the overall RAW optimal *** presented analytical framework can be applied to many other Wi-Fi standards that integrate periodic channel *** simulations using the mATLAB software validate the analytical model and prove the effectiveness of the proposed RAW configuration scheme.

关键词： IEEE 802.11ah Performance evaluation Renewal theory RAW mechanism Internet of things

Serological surveillance for SARS-coV-2 antibodies among students,faculty and staff within a large university system during the pandemic

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World Journal of Virology 2025年第1期14卷 99-107页

作者： marcos G Pinheiro Gabriela G O Alves maria Eduarda R conde Sofia L costa Regina c S Sant’Anna Isa m F Antunes mônica c carneiro Fabio S Ronzei Julia c Scaffo Felipe R Pinheiro Lialyz S Andre Helvecio c Povoa Valéria T Baltar Fabíola Giordani Eduarda S Hemerly Gisele c Alexandre Karla c de Paula márcio Watanabe Antonio claudio L da Nóbrega Jackeline christiane P Lobato Fabio Aguiar-Alves Laboratory of molecular Epidemiology and Biotechnology Rodolpho Albino University LaboratoryFluminense Federal UniversityNiterói 24241000Rio de JaneiroBrazil Estácio de SáUniversity Nova Friburgo 28611135Rio de JaneiroBrazil Pathology Program Medicine schoolFluminense Federal UniversityNiterói 24070090Rio de JaneiroBrazil Department of Pharmaceutical Sciences Lloyd L.Gregory School of PharmacyPalm Beach Atlantic UniversityWest Palm BeachFL 33401United States Health Institute of Nova Friburgo Fluminense Federal UniversityNova Friburgo 28613001Rio de JaneiroBrazil Department of Epidemiology and Biostatistics Institute of Collective Health(ISC)Fluminense Federal UniversityNiterói 24033900Rio de JaneiroBrazil Institute of Physical Education Fluminense Federal UniversityNiterói 24020005Rio de JaneiroBrazil Department of Statistics Fluminense Federal UniversityNiterói 24210200Rio de JaneiroBrazil Department of Physiology and Pharmacology Fluminense Federal UniversityNiterói 24210130Rio de JaneiroBrazil

BAcKGROUND At the end of December 2019,the world faced severe acute respiratory syndrome-coronavirus 2(SARS-coV-2),which led to the outbreak of coronavirus disease 2019(cOVID-19),associated with respiratory *** virus has shown significant challenges,especially for senior citizens,patients with other underlying illnesses,or those with a sedentary *** tests conducted early on have helped identify how the virus is transmitted and how to curb its *** study hypothesis was that the rapid serological test for SARS-coV-2 antibodies could indicate the immunoreactive profile during the cOVID-19 pandemic in a university *** To conduct active surveillance for serological expression of anti-SARS-coV-2 antibodies in individuals within a university setting during the cOVID-19 *** This sectional study by convenience sampling was conducted in a large university in Niteroi-RJ,Brazil,from march 2021 to July *** study population consisted of students,faculty,and administrative staff employed by the university.A total of 3433 faculty members,60703 students,and 3812 administrative staff were invited to *** were gathered through rapid serological tests to detect immunoglobulin(Ig)m and IgG against ***χ²or Fisher's exact test was used to conduct statistical analysis.A 0.20 significance level was adopted for variable selection in a multiple logistic regression model to evaluate *** A total of 1648 individuals were enrolled in the *** proportion of cOVID-19 positivity was 164/1648(9.8%).The adjusted logistic model indicate a positive association between the expression of Igm or IgG and age[odds ratio(OR)=1.16,95%cI:1.02-1.31](Pcontact with a cOVID-19-positive case(OR=3.49,95%cI:2.34-5.37)(Pceived the cOVID-19 vaccine(OR=2.33,95%cI:1.61-3.35)(Pcial isolation(OR=0.59,95%cI:0.41-0.84)(P<0.004).The likelihood of sho

关键词： Serological surveillance SARS-coV-2 antibodies cOVID-19 Serological rapid test Risk factors for cOVID-19

Effect of retained austenite and nonmetallic inclusions on the thermal/electrical properties and resistance spot welding nuggets of Si-containing TRIP steels

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International Journal of minerals,metallurgy and materials 2019年第1期26卷 52-63页

作者： V.H.Vargas I.mejía V.H.Baltazar-Hernández c.maldonado metallurgy and materials Research Institute Universidad Michoacana de San Nicolás de Hidalgo Edificio "U" Ciudad Universitaria materials Science and Engineering Program Autonomous University of Zacatecas

Five advanced high-strength transformation-induced plasticity(TRIP) steels with different chemical compositions were studied to correlate the retained austenite and nonmetallic inclusion content with their physical properties and the characteristics of the resistance spot welding nuggets. Electrical and thermal properties and equilibrium phases of TRIP steels were predicted using the JmatPro? software. Retained austenite and nonmetallic inclusions were quantified by X-ray diffraction and saturation magnetization techniques. The nonmetallic inclusions were characterized by scanning electron microscopy. The results show that the contents of Si, c, Al, and mn in TRIP steels increase both the retained austenite and the nonmetallic inclusion contents. We found that nonmetallic inclusions affect the thermal and electrical properties of the TRIP steels and that the differences between these properties tend to result in different cooling rates during the welding process. The results are discussed in terms of the electrical and thermal properties determined from the chemical composition and their impact on the resistance spot welding nuggets.

关键词： transformation-induced plasticity steel retained austenite non-metallic inclusions magnetic saturation electrical properties thermal properties resistance spot welding nugget

mesoscopic model for binary fluids

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Frontiers of physics 2017年第5期12卷 231-239页

作者： c. Echeverria K. Tucci O. Alvarez-Llamoza E. E. orozco-Guillén5 m. morales m. G. cosenza ceSimo Universidad de Los Andes Mérida 5251 Mérida Venezuela Grupo de caos y Sistemas complejos Centro de Fisica Fundamental Universidad de Los Andes Mérida Venezuela Departamento de Fisica FACYT Universidad de Carabobo Valencia Venezuela Facultad de Ingenierla Universidad Católica de Cuenca Ecuador programa Académico de Ingenierla en Energla Universidad Politécnica de Sinaloa 82199 Mazatldn Mexico Programa Académico de Ingenierla en Nanoteenologla Universidad Politécnica de Sinaloa 82199 Mazatldn Mexico

We propose a model for studying binary fluids based on the mesoscopic molecular simulation technique known as multiparticle collision, where the space and state variables are continuous, and time is discrete. We include a repulsion rule to simulate segregation processes that does not require calculation of the interaction forces between particles, so binary fluids can be described on a mesoscopic scale. The model is conceptually simple and computationally efficient; it maintains Galilean invariance and conserves the mass and energy in the system at the micro- and macro-scale, whereas momentum is conserved globally. For a wide range of temperatures and densities, the model yields results in good agreement with the known properties of binary fluids, such as the density profile, interface width, phase separation, and phase growth. We also apply the model to the study of binary fluids in crowded environments with consistent results.

关键词： multiparticle collision dynamics mesoscopic models phase separation interface dynamics

Gastric infiltration of diffuse large B-cell lymphoma: Endoscopic diagnosis and improvement of lesions after chemotherapy

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World Journal of Gastroenterology 2008年第27期14卷 4407-4409页

作者： Sergio Zepeda-Gómez Jesús camacho Edgar Oviedo-cárdenas carmen Lome-maldonado Department of Gastrointestinal Endoscopy Instituto Nacional de Ciencias Médicas y Nutrición "Salvador Zubirán" Department of Pathology Instituto Nacional de Ciencias Médicas y Nutrición "Salvador Zubirán"

Diffuse large B-cell lymphoma (DLBcL) is the most common histologic subtype of the non-Hodgkin’s lymphoma (NHL) accounting for about 40% of all NHLs. This is a case report about the endoscopic appearance of a DLBcL with infiltration to the stomach in a 39-year-old female. She had a 6-mo history of lumbar and left upper quadrant pain with intermittent episodes of melena. A computer tomograghy (cT) scan showed mural thickening of the gastric antrum. Endoscopic examination revealed multiple gastric ulcers. Definite diagnosis could be made by endoscopic biopsies and the patient had a good response to chemotherapy. This response correlated well with a further endoscopic follow-up. A follow-up endoscopic examination could be considered to evaluate a good response to chemotherapy in DLBcL patients with secondary gastric dissemination.

关键词： Diffuse large B-cell lymphoma Non-Hodgkin's lymphoma Gastric infiltration

Superplasticity of a friction stir processed overaged WE54 magnesium alloy

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Journal of magnesium and Alloys 2022年第11期10卷 3156-3166页

作者： Oscar A.Ruano marta Alvarez-Leal Alberto orozco-caballero Fernando carreño Physical metallurgy Department CENIM-CSICAv.Gregorio del Amo 828040 MadridSpain Department of R&D and programmes Technology Centre of Metal-Mechanical and Transport(CETEMET).Avda.1°de Mayos/n.LinaresJaén2370Spain Department of mechanical Engineering Chemistry and Industrial DesignPolytechnic University of MadridRonda de Valencia 328012MadridSpain

The coarse-grained WE54 magnesium alloy was heat treated in order to have minimum hardness minimizing the effects of precipitates and solid solution. Friction stir processing(FSP) was applied in severe conditions to obtain fine, equiaxed and highly misoriented grains, with grain sizes even less than 1 μm. The high severity of processing demonstrated to have a strong impact in the microstructure. consequently,the processed materials exhibited excellent superplasticity at the high strain rate 10^(-2)s^(-1), and temperatures between 300 and 400 ℃. The maximum tensile superplastic elongation of 756% was achieved at 400 ℃ thanks to the operation of grain boundary sliding mechanism(GBS). Besides the new data obtained through tensile testing, the paper deals with a transcendental question regarding the large differences in strain rate values at a given stress in the superplastic regime at maximum elongation compared to other magnesium-based alloys. With this is mind, 19 magnesium alloys from 22 different investigations were analyzed to give some light to this behavior that never was treated before. It is proposed that this behavior has to be attributed to the accommodation process, necessary for GBS to occur, which is hindered by reinforcing solutes.

关键词： WE54 magnesium alloy Friction stir processing Processing severity Superplasticity Grain boundary sliding Solutes

microstructural evaluation and nanohardness of an AlcocucrFeNiTi high-entropy alloy

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International Journal of minerals,metallurgy and materials 2019年第5期26卷 634-641页

作者： c.D.Gómez-Esparza R.Peréz-Bustamante J.m.Alvarado-orozco J.mu?oz-Salda?a R.martínez-Sánchez J.m.Olivares-Ramírez A.Duarte-moller centro de Investigación en materiales Avanzados (cImAV) Laboratorio Nacional de Nanotecnología cONAcYT-corporación mexicana de Investigación en materiales S.A.de c.V.(cOmImSA) centro de Ingeniería y Desarrollo Industrial Querétaro Campus centro de Investigación y de Estudios Avanzados del IPN Unidad Querétaro Universidad Tecnológica de San Juan del Río Escuela de Ingeniería civil Industrialy Mecánica Universidad De La Salle Bajío

An AlcocucrFeNiTi high-entropy alloy(HEA) was prepared by mechanical alloying and sintering to study the effect of Ti addition to the widely studied AlcocucrFeNi system. The structural and microstructural characteristics were investigated by X-ray diffraction(XRD), scanning electron microscopy(SEm), and transmission electron microscopy(TEm). The formation of four micrometric phases was detected: a cu-rich phase with a face-centered cubic(fcc) structure, a body-centered cubic(bcc) solid solution with cu-rich plate-like precipitates(fcc), an ordered bcc phase, and a tetragonal structure. The XRD patterns corroborate the presence of a mixture of bcc-, fcc-, and tetragonal-structured phases. The Vickers hardness of the alloy under study was more than twice that of the AlcocucrFeNi alloy. Nanoindentation tests were performed to evaluate the mechanical response of the individual phases to elucidate the relationship between chemical composition, crystal structure, and mechanical performance of the multiphase microstructure of the AlcocucrFeNiTi HEA.

关键词： high-entropy alloys mechanical alloying microstructure nanoindentation