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Acta Mathematica Sinica,English Series 2012年第3期28卷 561-580页

作者： rafael parra Manuel SAORIN Departamento de Clculo. Escuela Bsica Facultad de Ingeniería Universidad de los Andes Departamento de Matemticas Universidad de Murcia

Given a significative class F of commutative rings, we study the precise conditions under which a commutative ring R has an S-envelope. A full answer is obtained when F is the class of fields, semisimple commutative rings or integral domains. When .F is the class of Noetherian rings, we give a full answer when the Krull dimension of R is zero and when the envelope is required to be epimorphic. The general problem is reduced to identifying the class of non-Noetherian rings having a monomorphic Noetherian envelope, which we conjecture is the empty class.

关键词： Noetherian ring envelope local ring artinian ring Krull dimension

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Enhancement of Corrosion Resistance of NiCrFeBSi Coatings Obtained by Flame Thermal Spray Process Adding an Electroless Nickel Coating Ni-P

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Journal of Surface Engineered Materials and Advanced Technology 2017年第4期7卷 86-97页

作者： Arturo Barba-Pingarrón Raúl Valdez-Navarro Félix Sánchez-De Jesus Ana María Bolarín-Miró rafael González-parra Alba Covelo-Villar Miguel ángel Hernández-Gallegos Carlos Domínguez-Ríos Centro de Ingeniería de Superficies y Acabados (CENISA) Facultad de Ingeniería Universidad Nacional Autónoma de México 2 Nivel Edificio “T” (Bernardo Quintana) Circuito Exterior Ciudad Universitaria Ciudad de México México área Académica de Ciencias de la Tierra y Materiales Universidad Autónoma del Estado de Hidalgo Pachuca México Centro de Investigación en Materiales Avanzados Chihuahua México

Flame Thermal Spray (FTS) coatings frequently show some porosity and reduced adherence to substrate, which affect its properties, especially its corrosion resistance. In this work, the corrosion resistance of AISI 1018 carbon steel coated by different methods is compared: electroless nickel (EN) coating, NiCrFeBSi obtained by FTS, duplex coatings of an EN deposit on a layer of NiCrFeBSi obtained by FTS and a layer of NiCrFeBSi on an EN deposit. The coatings were characterized using optical microscopy and scanning electron microscopy techniques, EDS microprobe microanalysis, roughness as well as electrochemical polarization tests to obtain the corrosion rate. The results show the enhancement in the corrosion resistance in saline medium of the duplex coatings, especially of the EN coating on FTS layer.

关键词： Flame Thermal Spray Coatings Electroless Nickel Plating Duplex Coatings Corrosion Resistance

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Mathematical modeling for estimating influenza vaccine efficacy:A case study of the Valencian Community,Spain.

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Infectious Disease Modelling 2024年第3期9卷 744-762页

作者： Carlos Andreu-Vilarroig rafael J.Villanueva Gilberto González-parra Instituto de Matemática Multidisciplinar Universitat Politècnica de ValènciaValenciaSpain Department of Mathematics New Mexico TechSocorroNMUSA

Vaccine efficacy and its quantification is a crucial concept for the proper design of public health vaccination *** this work we proposed a mathematical model to estimate the efficacy of the influenza vaccine in a real-word *** particular,our model is a SEIR-type epidemiological model,which distinguishes vaccinated and unvaccinated ***,its dynamics is governed by a nonlinear system of ordinary differential equations,where the non-linearity arises from the effective contacts between susceptible and infected *** key aspects of this study is that we use a vaccine distribution over time that is based on real data specific to the elderly people in the Valencian Community and the calibration process takes into account that over one influenza season a specific proportion of the population becomes infected with *** consider the effectiveness of the vaccine,the model incorporates a parameter,the vaccine attenuation factor,which is related with the vaccine efficacy against the influenza *** this framework,in order to calibrate the model parameters and to obtain an influenza vaccine efficacy estimation,we considered the 2016–2017 influenza season in the Valencian Community,Spain,using the influenza reported cases of vaccinated and *** order to ensure the model identifiability,we choose to deterministically calibrate the parameters for different scenarios and we find the one with the minimum error in order to determine the vaccine *** calibration results suggest that the influenza vaccine developed for 2016–2017 influenza season has an efficacy of approximately 76.7%,and that the risk of becoming infected is five times higher for an unvaccinated individual in comparison with a vaccinated *** estimation partially agrees with some previous studies related to the influenza *** study presents a new integrated mathematical approach to study the influenza vaccine efficacy and gives f

关键词： Mathematical modeling Epidemiology SEIR Vaccine efficacy Influenza Valencian community

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Ayahuasca:Uses,Phytochemical and Biological Activities

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Natural Products and Bioprospecting 2019年第4期9卷 251-265页

作者： Edgar Antonio Estrella‑parra Julio Cesar Almanza‑Pérez Francisco Javier Alarcón‑Aguilar Laboratorio de Farmacología.Dpto.Ciencias de la Salud.Div.C.B.S.Universidad Autónoma Metropolitana Unidad Iztapalapa.Av.San Rafael Atlixco No.186Col.Vicentina09340 Mexico CDMXMexico Laboratorio de Fitoquímica Laboratorio de FarmacognosiaLaboratorio de Fisiología VegetalUnidad UBIPROFES-IztacalaUNAMTlalnepantla de Baz54090 Mexico CDMXMexico

Ayahuasca(caapi,yajé),is a psychoactive brew from the Amazon Basin region of South America traditionally considered a“master plant.”It is prepared as a decoction from Banisteriopsis caapi and Psychotria viridis,which it is thought that it stimulates creative thinking and visual *** healers of the Orinoco and Amazon basins have used traditionally ayahuasca as a healing tool for multiple purposes,particularly to treat psychological disorders in the patients,with some beneficial effects experimentally and clinically ***,several syncretic religions,as the“Uniao de Vegetal”(UDV)group in Brazil,have been spread around the *** use of ayahuasca has been popularized by internet and smart-shops,bringing the psychoactive substance to new highs,emerging new“ayahuasqueros.”Ayahuasca has alkaloids asβ-carbolines and dimethyltryptamines,which inhibit the monoamine oxidase and active the 5-HT_(2A)(5-hydroxytryptamine)receptor,respectively,resulting in hallucinations in the *** induces a psychedelic change in the anteroposterior coupling of the electrophysiological brain oscillations in *** ayahuasca beverage is generating pharmacological,commercial and spiritual interest among the scientific community,government people,and different populations *** goal of this article is to report about the uses,chemistry and biological activities of ayahuasca.

关键词： Ayahuasca Banisteriopsis caapi Psychotria viridis-dimethyltryptamine β-carbolines Psychotherapy

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