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Microstructures of Thermomechanically Treated Eutectoid Zn-Al Alloy

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Journal of Materials Science & Technology 1994年第2期10卷 121-126页

作者： Y. H.Zhu(Instituto de Investigaciones en Materiales, universidad nacional autonoma de mexico, mexico City, mexico) F.E.Goodwin (Addressed: Instituto de Investigaciones en Materiales, UNAM, Apdo. P70-360, mexico D.F.04510, mexico) (International Lead and Z universidad nacional autonoma de Mexico Mexico City Mexico

A continuously cast eutectoid Zn-Al alloy was extruded at about 250℃ and the complex microstructures of three phases (α. ε and η'E) were observed in the extruded eutectoid Zn-Al *** fcc Al-rich α phase appeared as isolated particles with clear boundaries instead of the α phase occurring with diffuse boundary within the dendrites of the as-cast structure. A new unstable phase η'E was determined to have hexagonal close packed crystal structure. The decomposed β's, phase comprised the matrix. The new phase η'E decompoeed and a four phase transformation α+ε T'+η occurred afterwards during the isothermal holding. The extruded alloy tended to be stable after these two phase transformations. The early shrinkage and the following increase in dimension were related to the decomposition of the new phase η'E and the four phase transformation.

关键词： Zn Al Microstructures of Thermomechanically Treated Eutectoid Zn-Al Alloy Met

Magnetic polarization of a Mn-doped semiconductor nanostructure controlled by an external bias

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Journal of Semiconductors 2015年第7期36卷 22-28页

作者： P.Paradeo Unstituto de Fisica Universidad Nacional Autonoma de Mexico

The interplay between the electric and magnetic properties in a double quantum well heterostructure doped by magnetic ions is theoretically investigated. In this material, the magnetism is mediated by the hole gas. The total magnetic polarization of the system is controllable by an external applied bias. The device has two equilibrium states （symmetric and antisymmetric configurations）. In the stable configuration （anti-ferromagnetic type）, the particle spin distribution is reversed in the adjacent wells. The stability of the system is investigated by simulating the interaction of the hole gas with the light. By using an ab initio method, we estimate the switching time of the device.

关键词： magnetic polarization quantum well stability

Condensed Extended Hyper-Wiener Index

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Chinese Journal of Structural Chemistry 2008年第9期27卷 1134-1140页

作者：李新华 Abraham F.Jalbout 吉智 College of Chemistry and Materials Engineering Wenzhou University Instituto de Quimica Universidad Nacional Autonoma de MexicoMexico D.F Instituto de fisica Universidad Nacional Autonoma de MexicoMexico D.F

According to the definitions of molecular connectivity and hyper-Wiener index, a novel set of hyper-Wiener indexes （Dn, ^mDn） were defined and named as condensed extended hyper-Wiener index, the potential usefulness of which in QSAR/QSPR is evaluated by its correlation with a number of C3-C8 alkanes as well as by a favorable comparison with models based on molecular connectivity index and overall Wiener index.

关键词： hyper-Wiener index (R) condensed extended hyper-Wiener index molecular connectivity index

Multitemporal landslide inventory analysis of an intertropical mountain in west-central mexico——Basis for hazard management

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Journal of Mountain Science 2022年第6期19卷 1650-1669页

作者： Alejandro Cesar VALdeS CARRERA Manuel E.MENDOZA Teodoro CARLÓN ALLENde Jose Luis MACIAS Centro de Investigaciones en Geografia Ambiental Universidad Nacional Autonoma de MexicoMorelia 58190Mexico Consejo nacional de Ciencia y Tecnologia-Instituto de Geofisica-Unidad Michoacan Universidad Nacional Autonoma de MexicoMorelia 58190Mexico Instituto de Geofisica-Unidad Michoacan Universidad Nacional Autonoma de MexicoMorelia 58190Mexico

Landslides in intertropical mountainous areas of mexico are a natural hazard that could potentially generate a disaster. despite this, many areas lack landslide inventories, making it difficult to monitor and efficiently manage the associated risks for local populations. For this reason, the aim of this research was to undertake a multitemporal landslide inventory and analyze its conditioning factors in the Pico de Tancítaro stratovolcano, which, in recent decades, has presented several high-risk geomorphological events with disastrous consequences for nearby localities. The spatial distribution of landslides and its conditioning factors were mapped at a 1:50,000 scale for the 1995-2020 period, through visual interpretation of orthophotos and satellite images(Landsat, SPOT, and SENTINEL). The conditioning factors that link the most to landslides were Quaternary andesite and basaltic andesite rocks;volcanic cones, mountain river valleys, and very steep to steep slopes(30° to >45°), oriented to the South, North, and East;Andosols and Leptosols;and the oyamel fir and mixed forests. 505 landslide events classified into slides and flows that occurred in 1995, 2004, 2010, and 2015 were identified. New scars generated by the reactivation of landslide processes were also observed. The landslides in the study area were triggered by torrential rains caused by hurricanes and tropical storms;such as hurricanes Alex and Patricia. The inventory and analysis of conditioning factors highlighted the distribution and dynamics of slides and flows in the study area. In addition, the most important factors for studies of landslide susceptibility, hazards, and risks in the Pico de Tancítaro stratovolcano were identified, contributing to the management of geomorphological risks in intertropical mountain areas.

关键词： Geomorphology Mass wasting Natural hazards Pico de Tancítaro stratovolcano Risk management

Transcriptional cofactors Ski and SnoN are major regulatorsof the TGF-β/Smad signaling pathway in health and disease

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Signal Transduction and Targeted Therapy 2018年第1期3卷 184-198页

作者： Angeles C.Tecalco-Cruz Diana G.Rios-Lopez Genaro Vazquez-Victorio Reyna E.Rosales-Alvarez Marina Macias-Silva Instituto de Investigaciones Biomedicas at universidad nacional autonoma de mexico Mexico city 04510Mexico Instituto de Fisiologia Celular at universidad nacional autonoma de mexico Mexico city 04510Mexico Facultad de Ciencias at universidad nacional autonoma de mexico Mexico city 04510Mexico

The transforming growth factor-β(TGF-β)family plays major pleiotropic roles by regulating many physiological processes in development and tissue *** TGF-βsignaling pathway outcome relies on the control of the spatial and temporal expression of>500 genes,which depend on the functions of the Smad protein along with those of diverse modulators of this signaling pathway,such as transcriptional factors and ***(Sloan-Kettering Institute)and SnoN(Ski novel)are Smadinteracting proteins that negatively regulate the TGF-βsignaling pathway by disrupting the formation of R-Smad/Smad4 complexes,as well as by inhibiting Smad association with the p300/CBP *** Ski and SnoN transcriptional cofactors recruit diverse corepressors and histone deacetylases to repress gene *** TGF-β/Smad pathway and coregulators Ski and SnoN clearly regulate each other through several positive and negative feedback ***,these cross-regulatory processes finely modify the TGF-βsignaling outcome as they control the magnitude and duration of the TGF-β*** a result,any alteration in these regulatory mechanisms may lead to disease ***,the design of targeted therapies to exert tight control of the levels of negative modulators of the TGF-βpathway,such as Ski and SnoN,is critical to restore cell homeostasis under the specific pathological conditions in which these cofactors are deregulated,such as fibrosis and cancer.

关键词： SnoN homeostasis Smad

Kinetics of the H＋-ATPase from Dry and 5-Hours- Imbibed Maize Embryos in Its Native, Solubilized, and Reconstituted Forms

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Molecular Plant 2011年第3期4卷 505-515页

作者： Sobeida Sanchez-Nieto Consuelo Enriquez-Arredondo Fernando Guzmbn-Chavez Rolando Hern&ndez-Munoz Jorge Ramirez Marina Gavilanes-Ruiz departamento de Bioquimica Facultad de Quimica Conjunto E. Universidad Nacional Autonoma de Mexico Cd Universitaria 04360 Mexico DF Mexico Instituto de Fisiologfa Celular Universidad Nacional Autonoma de Mexico Cd Universitaria 04360 Mexico DF Mexico

Membranes undergo recovery upon rehydration in seed germination. Previous work has described that the plasma membrane H＋-ATPase from maize embryos adopts two different forms at 0 and 5 h of imbibition. We investigated how the kinetics of these two forms could be affected by alterations in the plasma membrane （PM）. In comparison to the O-h, PMs from the 5-h imbibed embryos showed changes in glycerophospholipid composition, decrease in leakage, and increase in fluidity. Kinetics of the PM H^-ATPase from 0 and 5-h imbibed embryos showed negative cooperativity, With the removal of the membrane environment, the activity of the enzymes shifted to a more complex kinetics, displaying two enzyme components. Lipid reconstitution produced one component with positive cooperativity. In all cases, enzymes from 0 and 5-h imbibed embryos presented similar kinetics with some quantitative differences. These results indicate that the two enzyme forms have the potential ability to respond to changes in the membrane enyiror^rpent, but the fact that they do not show differences in the native membranes at 0 or 5 h implies that modifications in the membrane are not drastic enough to alter their kinetics, or that they are able to preserve their boundary lipids or associated proteins and thus retain the same kinetic behavior.

关键词： ATPase activity H^-ATPase maize germination plasma membrane H+-ATPase plasma membrane Zea mays.

Pulsatile electroosmotic flow of a Maxwell fluid in a parallel flat plate microchannel with asymmetric zeta potentials

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Applied Mathematics and Mechanics(English Edition) 2018年第5期39卷 667-684页

作者： M.PERALTA O.BAUTISTA F.MENdeZ E.BAUTISTA Seccion de Estudios de Posgrado e Investigacion ESIME Azcapotzalco Instituto Politecnico NacionalCiudad de Mexico 02250Mexico Facultad de Ingeniería Universidad Nacional Autonoma de MexicoCiudad de Mexico 04510Mexico

The pulsatile electroosmotic flow （PEOF） of a Maxwell fluid in a parallel flat plate microchannel with asymmetric wall zeta potentials is theoretically analyzed. By combining the linear Maxwell viscoelastic model, the Cauchy equation, and the electric field solution obtained from the linearized PoissomBoltzmann equation, a hyperbolic par- tial differential equation is obtained to derive the flow field. The PEOF is controlled by the angular Reynolds number, the ratio of the zeta potentials of the microchannel walls, the electrokinetic parameter, and the elasticity number. The main results obtained from this analysis show strong oscillations in the velocity profiles when the values of the elas- ticity number and the angular Reynolds number increase due to the competition among the elastic, viscous, inertial, and electric forces in the flow.

关键词： pulsatile electroosmotic flow (PEOF) flat plate microchannel asymmetric zeta potential Maxwell fluid

The role of the TrkB-T1 receptor in the neurotrophin-4/5 antagonism of brain-derived neurotrophic factor on corticostriatal synaptic transmission

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Neural Regeneration Research 2020年第11期15卷 1973-1976页

作者： Elizabeth Hernandez-Echeagaray Unidad de Investigacion en Biomedicina FES-Iztacala Universidad Nacional Autonoma de MexicoMexicoMexico

This manuscript reviews the function and fundamental characteristics of the neurotrophins and their receptors to introduce the reader to the differential effects exhibited by the neurotrophins;brain-derived neurotrophic factor and neurotrophin 4/5 when acted together after sequential *** neurotrophin 4/5 exhibits an inhibitory action on the modulatory effect of brain-derived neurotrophic factor in corticostriatal synapses when they are administered sequentially(brain-derived neurotrophic factor to neurotrophin 4/5).This inhibitory effect has not been previously documented and is relevant for these neurotrophins as both of them stimulate the TrkB *** additive effect of these neurotrophins is also discussed and occurs when neurotrophin 4/5 exposure is followed by brain-derived neurotrophic factor in a mouse model of striatal *** and additive effects of both neurotrophins are accompanied by changes in the expression of the TrkB receptor isoforms,specifically TrkB-T1 and TrkB-FL,as well as differences in phosphorylation levels of the TrkB *** results of the experiments described raise several questions to inquire about the role that TrkB-T1 receptor plays in striatal physiology,as well as the functional relevance of the interaction of brain-derived neurotrophic factor and neurotrophin 4/5 in the brain and more specifically at the striatal circuits in normal as well as pathological conditions.

关键词： brain-derived neurotrophic factor neurotrophin 4/5 occlusive striatum synergic TrkB-FL TrkB-T1

Phase equilibrium modelling of the amphibolite facies metamorphism in the Yelapa-Chimo Metamorphic Complex, mexico

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Geoscience Frontiers 2021年第1期12卷 293-312页

作者： Fabian Gutierrez-Aguilar Peter Schaaf Gabriela Solís-Pichardo Gerardo F.Arrieta-García Teodoro Hernandez-Trevino Carlos Linares-Lopez Posgrado en Ciencias de la Tierra Instituto de GeofísicaUniversidad Nacional Autonoma de MexicoAv.Universidad 3000Ciudad de Mexico04510Mexico Laboratorio Universitario de Geoquímica Isotopica(LUGIS) Instituto de GeofísicaUniversidad Nacional Autonoma de MexicoAv.Universidad 3000Ciudad de Mexico04510Mexico Laboratorio Universitario de Geoquímica Isotopica(LUGIS) Instituto de GeologíaUniversidad Nacional Autonoma de MexicoAv.Universidad 3000Ciudad de Mexico04510Mexico Instituto de Geofísica Universidad Nacional Autonoma de MexicoAv.Universidad 3000Ciudad de Mexico04510Mexico

The Yelapa-Chimo Metamorphic Complex forms part of the Jalisco Block in western mexico and exposes a wide range of Early Cretaceous metamorphic rocks;such as paragneiss,orthogneiss,amphibolites,and ***,the pressure-temperature(P-T)conditions of metamorphism and partial melting remain poorly studied in the *** elucidate metamorphic P-T conditions,phase equilibrium modelling was applied to two sillimanite-garnet paragneisses,one amphibole-orthogneiss,and one ***-garnet paragneisses exhibit a lepidoblastic texture with a biotite+sillimanite+kyanite+garnet+quartz+plagioclase+K-feldspar mineral ***-orthogneiss and amphibolite display a nematoblastic texture with an amphibole+(1)plagioclase+quartz+(1)titanite assemblage and an amphibole+(2)plagioclase+(2)titanite+ilmenite retrograde mineral *** calculated for the two sillimanite-garnet paragneiss samples show P-T peak conditions at~6-7.5 kbar and~725-740℃.The results for amphibole-orthogneiss and the amphibolite yield P-T peak conditions at~8.5-10 kbar and~690-710℃.The mode models imply that metasedimentary and metaigneous units can produce up to~20 vol%and~10 vol%of melt,*** within a closed system during isobaric heating suggests that melt compositions of metasedimentary and metaigneous units are likely to have direct implications for the petrogenesis of the Puerto Vallarta *** new data indicate that the Yelapa-Chimo Metamorphic Complex evolved through a metamorphic gradient between~23-33℃km^-1and the metamorphic rocks formed at depths between~22 km and~30 km with a burial rate of~2.0 km Ma^-***,the P-T data for both metasedimentary and metaigneous rocks provide new constraints on an accretionary framework,which is responsible for generating metamorphism and partial melting in the YelapaChimo Metamorphic Complex during the Early Cretaceous.

关键词： Phase equilibrium modelling Yelapa-Chimo Metamorphic Complex Amphibolite facies Partial melting