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Southward Migration of Magmatic Activity in the Colima Volcanic Complex, Mexico: An Ongoing Process

International Journal of Geosciences 2015年第9期6卷 1077-1099页

作者： Román Alvarez Vsevolod Yutsis instituto de Investigaciones en matemáticas aplicadas y en Sistemas Universidad Nacional Autónoma de México Ciudad Universitaria México DF México instituto Potosino de Investigación Científica y Tecnológica San Luis Potosí México

The Colima Volcanic Complex trends in a nearly N-S direction in western Mexico, and one of its?structures, Colima volcano, is the most historically active volcano in the country. Immediately to the?N, there is another volcanic center called El Cántaro volcano, whose activity started around 1.7 Ma in its N portion and migrated to the S in various episodes. Volcanic activity migrated further south, from El Cántaro to the Colima Volcanic Complex where the southernmost manifestation, Hijos del Volcán domes, is located on the south slope of Fuego volcano. The above date appears to mark initiation of the rather continuous volcanic activity in the area. It has been noted that these volcanic manifestations lie on, or near the Rivera-Cocos inland plate boundary. Colima’s Fuego volcano is also the closest to the Middle America Trench, among the polygenetic volcanoes in Mexico. We submit that the anomalous location of volcanism in this area originates in an anomalous subduction process of the Rivera and Cocos plates and evoke a tectonic model, proposed elsewhere, to support the idea. Modeling gravimetric and aeromagnetic data we locate the magma chambers of the Fuego (active) and Nevado (extinct) volcanoes within a 65 mGals negative Bouguer anomaly elongated in a nearly N-S direction. The corresponding aeromagnetic map displays a magnetic high over the southern portion of the Fuego volcano edifice. We found two additional, associated structures whose anomalies have not been previously reported, which appear to follow the southward magmatic migration pattern. One of them is a collapse structure with a circular topographic expression, and the southernmost is a low-density intrusion ~1 km below sea level, associated with a moderate topographic bulge at the surface that we interpret as a magma body. Five lines cross the anomalies;gravimetric and magnetic fields are concurrently modeled along them to locate the magmatic bodies. In addition to the 2-D models we perform 3-D gravimetric and magnetic inversions. For each field a 3-D

关键词： Colima Volcanic Complex Magma Chambers Colima Volcanoes Gravimetric Modeling Magnetic Modeling

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Reiterated homogenization of a laminate with imperfect contact:gain-enhancement of effective properties

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Applied Mathematics and Mechanics(English Edition) 2018年第8期39卷 1119-1146页

作者： F.E.ALVAREZ-BORGES J.BRAVO-CASTILLERO M.E.CRUZ R.GUINOVART-DIAZ L.D.PEREZ-FERNANdeZ R.RODRIGUEZ-RAMOS F.J.SABINA Facultad de matematica y Computacion Departamento de MatematicaUniversidad de La HabanaSan Lazaro y LHabana 4La HabanaCP 10400Cuba departamento de matematicas y Mecanica Universidad Nacional Autonoma de MexicoInstituto de Investigaciones en Matematicas Aplicadas y en Sistemas01000 CDMXAP 20-126M′exico departamento de Engenharia Mecanica Universidade Federal do Rio de JaneiroPolitecnica/COPPECaixa Postal 68503Rio de JaneiroRJCEP 21941-972Brasil departamento de matematica e Estatistica Universidade Federal de PelotasCaixa Postal 354PelotasRio Grande do SulCEP 96010-900Brasil

A family of one-dimensional(1D) elliptic boundary-value problems with periodic and rapidly-oscillating piecewise-smooth coefficients is considered. The coefficients depend on the local or fast variables corresponding to two different structural scales. A finite number of imperfect contact conditions are analyzed at each of the scales. The reiterated homogenization method(RHM) is used to construct a formal asymptotic solution. The homogenized problem, the local problems, and the corresponding effective coefficients are obtained. A variational formulation is derived to obtain an estimate to prove the proximity between the solutions of the original problem and the homogenized problem. Numerical computations are used to illustrate both the convergence of the solutions and the gain of the effective properties of a three-scale heterogeneous 1D laminate with respect to their two-scale counterparts. The theoretical and practical ideas exposed here could be used to mathematically model multidimensional problems involving multiscale composite materials with imperfect contact at the interfaces.

关键词： reiterated homogenization method(RHM) imperfect contact variational formulation effective coefficient gain

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Rare-Earth Doped GdVO₄ by Sol-Gel Method: Structural and Luminescence Properties

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World Journal of Engineering and Technology 2022年第4期10卷 907-922页

作者： D. Y. Medina-Velázquez A. D. J. Morales-Ramírez A. A. Morales-Hernández B. Gonzalez L. Ramírez-García E. Garfías-García J. Oliva C. R. Garcia J. Reyes-Miranda M. A. Barron E. Osorio-de-la-Rosa Universidad Autónoma Metropolitana-Azcapotzalco Ciencias Básicas e Ingeniería Reynosa México instituto Politécnico Nacional CIITEC IPN Cerrada de CECATI S/N Col. México City México instituto Politécnico Nacional ESIQIE IPN México City México CONACyT-División de Materiales Avanzados Instituto Potosino de Investigación Científica y Tecnológica A. C. San Luis Potosí México Facultad de Ciencias Físico matemáticas Universidad Autónoma de Coahuila Edif. A Unidad Camporredondo Saltillo México Comonfort Col. del Bosque. C.P. 77019 Chetumal Quintana Roo México.6 CONACYT-Universidad Autónoma del Estado de Quintana Roo Boulevard Bahía s/n esq. Ignacio Chetumal México

Rare earths have been extensively developed in recent years, however, new hosts allow high excitation and emission efficiency, in this sense, gadolinium vanadate has been extensively studied and in previous works it has been widely used in down conversion systems. Because of the strong absorption of the VO4 groups and efficient energy transfer from GdVO4 to lanthanide ions, in this work its up-conversion properties were studied when is co-doped with Yb3+, X3+ where X = Tm, Er and Ho. The powders synthesized presented a high crystallinity and a rounded morphology and exhibit a high luminescence when are excited with IR radiation.

关键词： Gadolinium Rare Earths Up Convertion

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Study of the (Ca1–xSrx) RuO3System with Nano-Crystals Prepared by the Solid-State Reaction Method

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Materials Sciences and Applications 2015年第1期6卷 16-22页

作者： Adolfo Quiroz Elizabeth Chavira José Eduardo Espinosa Rodolfo Palomino-Merino Ernesto Esteban Marinero Masaya Nishioka Valentín García-Vázquez Facultad de Ciencias Fí sico-matemá ticas Postgrado en F&iacute sica aplicada Benem&eacute rita Universidad Autónoma Puebla Ciudad Universitaria Puebla M&eacute xico instituto de Investigaciones en Materiales Universidad Nacional Autónoma de M&eacute xico M&eacute xico D.F. M&eacute xico Purdue University West Lafayette IN USA Hitachi san José Research Center San Jos&eacute California USA instituto de Fí sica LRT Benem&eacute rita Universidad Autónoma de Puebla Puebla M&eacute xico

We present a study of their structure, morphology, electrical and magnetic properties on the (Ca1–xSrx) RuO3 system for x = 0.0, 0.07, 0.10, 0.15 and 1.0. The samples were prepared by the solidstate reaction method in air at ambient pressure and heat in the 700℃ - 800℃ range for 48 h. By X-ray powder diffraction (XRD), we determine a solid solution until x = 0.15. Scanning electron microscopy (SEM) indicates that the particle size is 77 - 266 nm. The resistance measurements, as a function of temperature measurements from 7 to 300 K the (Ca1–xSrx) RuO3 system for x = 0.0, 0.07, 0.10, 0.15 and 1.0 show a metallic behaviour. We can even observe that the resistance of the samples is due to the partial substitution of Sr2+ ions and Ru ion valence. Finally, the sample x = 0.07 has a magnetization applied high field to 10 K, whereas that to 300 K does not have a magnetization.

关键词： Solid-State Reaction XRD SEM Electric Resistivity Magnetic Properties

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Structural and Magnetic Properties of Monophasic Maghemite (γ-Fe2O3) Nanocrystalline Powder

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Advances in Nanoparticles 2014年第3期3卷 114-121页

作者： Juan Adrián Ramos Guivar Arturo Isaías Martínez Ana Osorio Anaya luis de Los santos Valladares Lizbet León Félix Angel Bustamante Dominguez Cavendish Laboratory Department of Physics University of Cambridge Cambridge UK Centro de Investigación y Estudios Avanzados del instituto Politécnico Nacional Cinvestav Unidad Saltillo Ciudad de México México Ciudad de México México Laboratorio de Cerámicos y Nanomateriales Facultad de Ciencias Físicas Universidad Nacional Mayor de San Marcos Lima Perú Laboratorio de Nanotecnología e Innovación Tecnológica Departamento de Química e Ingeniería Química Universidad Nacional Mayor de San Marcos Lima Perú Núcleo de Física aplicada Instituto de Física Universidade de Brasília Brasília Brasil

Structural and magnetic studies of monophasic maghemite (γ-Fe2O3) magnetic nanocrystallites (MNCs) synthesized by the co-precipitation chemical route are reported in this paper. For the synthesis, a starting precursor of magnetite (Fe3O4) in basic medium was oxidized at room temperature by adjusting the pH = 3.5 at 80°C in an acidic medium without surfactants. X-ray diffraction (XRD) pattern shows widened peaks indicating nanometric size and Rietveld Refinement confirms only one single-phase assigned to γ-Fe2O3 MNCs. High Resolution Transmission Electron Microscopy (HR-TEM) demonstrates the formation of nanoparticles with diameter around D ≈ 6.8 ± 0.1 nm which is in good agreement with Rietveld Refinement (6.4 ± 1 nm). A selected area electron diffraction pattern was carried out to complement the study of the crystalline structure of the γ-Fe2O3 MNCs. M(H) measurements taken at different temperatures show almost zero coercivity and remanence indicating superparamagnetic domain and high magnetic saturation.

关键词： Monophasic Nanomaghemite Rietveld Refinement TEM SAED M-H Loops ZFC

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