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Influence of parameters on the microstructure of a duplex stainless steel joint welded by a GMAW welding process

Progress in Natural Science:Materials International 2022年第4期32卷 415-423页

作者： Sandra Chacón-Fernández Antonio Portolés García Gerardo Romaní Labanda Universidad Politécnica de Madrid Escuela Técnica Superior de Ingenieros Industriales UPM

Duplex stainless steels(DSSs) are widely used in industry for their desirable properties. Any fusion welding technique modifies the microstructure and, consequently, the properties of the material. This paper presents a parametric study of the variables that determine the energy contribution(current, voltage and welding speed) and the structural modifications produced during gas metal arc welding. The analysis comprises metallographic study,phase balance, dimensioning of the weld beads and tensile and hardness tests. The influence of the variables studied on the thermal cycles obtained(temperatures reached and cooling rate) was determined by using a finite element model. The results showed that, in addition to the indicated parameters, the parameter power transfer per volume(W/m3) and the geometry in the bead must be controlled due to their influence on the heat flow distribution and phase balance.

关键词： Welding Heat input GMAW Duplex stainless steels (DSS) Finite element model (FEM)

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Refractive errors among children, adolescents and adults attending eye clinics in Mexico

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International Journal of Ophthalmology(English edition) 2017年第5期10卷 796-802页

作者： Francisco Gomez-Salazar Abraham Campos-Romero Humberto Gomez-Campana Cinthia Cruz-Zamudio Mariano Chaidez-Felix Nidia Leon-Sicairos Jorge Velazquez-roman Hector Flores-Villasenor Secundino Muro-Amador Alma Marlene Guadron-Llanos Javier J.Martinez-Garcia Joel Murillo-Llanes Jaime Sanchez-Cuen Alejando Llausas-Vargas gerardo Alapizco-Castro Ana Irineo-Cabrales Enrique Graue-Hernandez Tito Ramirez-Luquin Adrian Canizalez-roman Salud Digna Para Todos I.A.P Culiacan Sinaloa 80000Mexico CIASaP School of Medicine Autonomous University of Sinaloa Culiacan Sinaloa 80246 Mexico Pediatric Hospital of Sinaloa Culiacan Sinaloa 80200Mexico The Women's Hospital Secretariat of Health Culiacan Sinaloa 80127 Mexico Department of Gastroenterology Regional Hospital ISSSTECuliacan 80230 Sinaloa Mexico Education and Research Department Regional general Hospital No. 1 IMSS Culiacan Sinaloa 80220 Mexico Department of Cornea and Refractive Surgery Institute of Ophthalmology 'Conde de Valenciana' Mexico City 06800Mexico

AIM：To assess the proportion of refractive errors in the Mexican population that visited primary care optometry clinics in fourteen states of Mexico. METHODS：Refractive data from 676 856 patients aged 6 to 90 y were collected from optometry clinics in fourteen states of Mexico between 2014 and 2015. The refractive errors were classified by the spherical equivalent（SE）, as follows：sphere＋？ cylinder. Myopia（SE〉-0.50 D）, hyperopia（SE〉＋0.50 D）, emmetropia（-0.50≤SE≤＋0.50）, and astigmatism alone（cylinder≥-0.25 D）. A negative cylinder was selected as a notation.RESULTS：The proportion（95% confidence interval） among all of the subjects was hyperopia 21.0%（20.9-21.0）, emmetropia 40.7%（40.5-40.8）, myopia 24.8%（24.7-24.9） and astigmatism alone 13.5%（13.4-13.5）. Myopia was the most common refractive error and frequency seemed to increase among the young population（10 to 29 years old）, however, hyperopia increased among the aging population（40 to 79 years old）, and astigmatism alone showed a decreasing trend with age（6 to 90y; from 19.7% to 10.8%）. There was a relationship between age and all refractive errors（approximately 60%, aged 50 and older）. The proportion of any clinically important refractive error was higher in males（61.2%） than in females（58.3%; P〈0.0001）. From fourteen states that collected information, the proportion of refractive error showed variability in different geographical areas of Mexico.CONCLUSION：Myopia is the most common refractive error in the population studied. This study provides the first data on refractive error in Mexico. Further programs and studies must be developed to address the refractive errors needs of the Mexican population.

关键词： refractive errors hyperopia myopia astigmatism

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