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Structural studies of BaTiO_3:Er^(3+) and BaTiO_3:Yb^(3+) powders synthesized by hydrothermal method

Journal of Rare Earths 2014年第11期32卷 1016-1021页

作者： Garrido-hernández A García-murillo A Carrillo-Romo F de J Cruz-Santiago L A Chadeyron G morales-Ramírez A de J Velumani S T.A. Post-graduate Student. Instituto Politécnico nacional CIITEC IPN Cerrada de Cecati S/N. Col. Santa Catarina Azcapotzalco México D.F. C.P. 02250 México D.F México Instituto Politécnico nacional CIITEC IPN Cerrada de Cecati S/N. Col. Santa Catarina Azcapotzalco México D.F. C.P. 02250 México D.F Departament of Engineering materials Tecnológico de Estudios Superiores de Coacalco (TESCo) Av. 16 de Septiembre # 54 Cabecera Municipal C.P. 55700 Coacalco de Berriozábal Estado de México Institut de Chimie de Clermont-Ferrand UMR 6296 CNRS / UBP / ENSCCF 24 avenue des Landais BP 80026 63171 Aubière Cedex – France Department of Electrical Engineering (SEES) Centro de Investigación y de Estudios Avanzados del IPN Av. Instituto Politécnico Nacional 2508 Col. San Pedro Zacatenco C.P. 07360 Mexico D.F. Mexico

Erbium and ytterbium doped barium titanate nanopowders were prepared using the hydrothermal method. A barium titanate structure doped with rare earth ions manifested new characteristics and improved the field of application of optical devices such as trichromatic tubes, LCD displays, lamps, and infrared lasers. In this work, BaTiO3：Er3＋ and BaTiO3：Yb3＋ were prepared using barium chloride [BaCl2], titanium butoxide [C16H36O4Ti], erbium chloride [ErCl3] and ytterbium chloride [YbCl3] as precursors. Anhydrous methanol was employed as a solvent. metallic potassium was used to promote solubility in the system and increase the pH to 13. This method yielded the formation of a predominantly cubic structure in both Er3＋ and Yb3＋ doped BaTiO3 powders. Characteristic bondings of BaTiO3 were observed with FT-IR spectroscopy. The predominantly cubic structure was confirmed by X-ray diffraction and micro-Raman analyses. The particle size（～30 nm） was estimated using the Scherrer equation and X-ray diffraction data. The results were presented and discussed.

关键词： nanopowders hydrothermal BaTiO3:Er3+ BaTiO3:Yb3+ rare earths

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Electrochemical Corrosion Study in H₂SO₄ of niAl with Cu Additions, microstructure and micro-Hardness at Room Temperature

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Journal of minerals and materials Characterization and Engineering 2022年第3期10卷 225-241页

作者： Jesús m. colín de la Cruz Sergio A. Serna Barquera Alvaro Torres-Islas Arturo molina-Ocampo Edgar Valenzuela José G. González Rodríguez Universidad Autónoma del Estado de morelos Facultad de Ciencias Químicas e Ingeniería UAEM-FCQeI. Av. Universidad 1001Colonia Chamilpa Cuernavaca Morelos México Universidad Autónoma del Estado de morelos Centro de Investigación en Ingeniería y Ciencias Aplicadas UAEM-CIICAp Cuernavaca Morelos México UABC Baja California Sur México

For many years, intermetallic materials promise applications in a wide variety of technology areas. niAl intermetallic compound is material that exhibits important characteristics such as high corrosion resistance and low density besides its ability to retain strength and stiffness at elevated temperatures. However niAl intermetallic is too hard, brittle and exhibits very low ductility at room temperature being the reason because this material is not yet available for structural applications. In order to increase the ductility of the niAl intermetallic compound, the addition of a third alloying element has been proved, nevertheless it is important to determine if such additions decrease or increase the hardness and the corrosion resistance of the alloy. So, the present investigation reports the corrosion performance of the niAl intermetallic compound modified with Cu, emphasizing the EIS analysis and the relation between physical parameters and the modelling equations used in the Equivalent Electric Circuit. It was found that the addition of Cu promotes the formation of the γ’-ni3Al phase in Cu contents greater than 15 at. %, in addition to a decrease in micro hardness and an increment in the Icorr values. In this way, the electrochemical characterization evidenced a high corrosion resistance of these intermetallic alloys.

关键词： niAl-Cu Corrosion Behavior Electrochemical Impedance Spectrum Vickers micro Hardness microstructure

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Assessing above-ground biomass-functional diversity relationships in temperate forests in northern mexico

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Forest Ecosystems 2021年第1期8卷 95-108页

作者： Benedicto Vargas-Larreta Jorge Omar López-martínez Edgar J.González JoséJavier Corral-Rivas Francisco Javier hernández Tecnológico nacional de méxico/Instituto Tecnológico de El Salto 34942 El SaltoDurangoMexico Cátedras CONACYT1582Av.Insurgentes SurCiudad de MéxicoMexico El colegio de la Frontera Sur 77014ChetumalQuintana RooMexico Departamento de Ecología y Recursos naturales Facultad de CienciasUniversidad Nacional Autónoma de MéxicoCiudad de MéxicoMexico Facultad de Ciencias Forestales Universidad Juárez del Estado de DurangoRío Papaloapan y Blvd.Durango s/nCol.Valle del Sur34120 DurangoMexico

Background:Studies on the relationship between biodiversity and ecosystem productivity have suggested that species richness and functional diversity are the main drivers of ecosystem *** patterns on this relationship have been found,including positive,unimodal,negative,and neutral trends,keeping the issue *** this study,taxonomic diversity and functional diversity as drivers of above-ground biomass(AGB)were compared,and the mechanisms that influence biomass production were investigated by testing the complementarity and the mass-ratio ***:Using data from 414 permanent sample plots,covering 23%of temperate forest in the Sierra madre Oriental(méxico),we estimated the above-gound biomass(AGB),taxonomic and functional diversity indices,as well as community weighted mean values(CWm)for three functional traits(maximum height,leaf size and wood density)for trees≥7.5 cm DBH,in managed and unmanaged *** compare taxonomic diversity differences between managed and unmanaged stands we carried out a rarefaction ***,we evaluated the relationship between AGB and taxonomic and functional diversity metrics,as well as CWm traits throught spatial autoregressive ***:We found a hump-shaped relationship between AGB and species richness in managed and unmanaged *** of maximum height was the most important predictor of AGB in both stands,which suggested that the mechanism underlaying the AGB-diversity relationship is the dominance of some highly productive species,supporting the mass-ratio ***-ground biomass was significantly correlated with three of the five functional diversity metrics,CWm maximum height and species *** results show the importance of taking into account spatial autocorrelation in the construction of predictive models to avoid spurious patterns in the AGBdiversity ***:Species richness,maximum height,functional richness,functional dispersion and Rao

关键词： Taxonomic diversity Functional diversity Complementarity hypothesis mass-ratio hypothesis

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Implications of Cytogenetic Abnormalities and Azoospermia Factor microdeletions in Assisted Procreation

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Journal of Reproduction and Contraception 2007年第3期18卷 231-235页

作者： Rima Dada R Kumar m Bilal Shamsi Sarabpreet Singh col R K Sharma A Varshney Laboratory of molecular Reproduction and Genetics Department of AnatomyAIIMS N Delhi 110029 India Anatomy Department AIIMSN Delhi 110029 India ART centre Obstretics and Gynaecology Department Army Research and Referral hospitalNew Delhi India AIImS N Delhi 110029 India

Assisted procreation techniques have revolutionized the management of infertility and have offered hope to millions of infertile couples. The main aim of these procedures is to produce healthy offspring. However recent studies on short term outcome of ART have reported a higher incidence of low birth weight, development delay, imprinting defects, sex and autosomal structural abnormalities, major and minor congenital malformation and certain cancers in babies conceived via ART. Further the health of ART conceived children beyond the neonatal period have been less well evaluated. A large number of infertile couples opting for ART have an underlying genetic aetiology. These genetic aberrations are iatrogenitically transmitted via ART. Thus it is important that all couples undergo a detailed and comprehensive genetic evaluation prior to ART.

关键词： genetics chromosomal abnormality AZF Yq microdeletion assisted reproduction ART

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Determination of the Sound Absorption Capacity of Hydraulic Concrete mixtures Added with Waste Tire Rubber

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Journal of minerals and materials Characterization and Engineering 2023年第5期11卷 197-211页

作者： maría Luisa moguel Pacheco Fermín Castillo mejía Yamilet Rodríguez Lazcano Andrés Aguilar negrete Arturo molina Ocampo Jesús mario colín de la Cruz Universidad Autónoma del Estado de morelos Facultad de Ciencias Químicas e Ingeniería Programa Educativo de Ingeniería Industrial Cuernavaca México Universidad nacional Autónoma de méxico Instituto de Ciencias Físicas Cuernavaca México Universidad Autónoma de nayarit Unidad Académica de Ciencias Básicas e Ingeniería Tepic México Universidad Autónoma del Estado de morelos Centro de Investigación en Ingeniería y Ciencias Aplicadas Cuernavaca México

There are different types of pollutants that are harmful to the environment, including smog, chemicals that are dumped into rivers, scrap tires, etc. The latter have the particularity that it is not possible to recycle them to manufacture new tires. In the present work, hydraulic concrete plates added with waste tire rubber were manufactured to modify their sound absorption capacity. It was found that the rubber additions produce changes in the density of the material and in the sound absorption capacity. When the material is exposed to high-frequency sounds that correspond to high-pitched sounds, its absorption capacity increases. On the contrary, when the test frequency is low, that is, bass sounds, the sound absorption capacity decreases. The results obtained in this work suggest that the proposed mixtures are suitable for the possible manufacture of acoustic insulating shields.

关键词： Hydraulic Concrete Waste Tire Rubber Sound Absorption noise Reduction Coefficient

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Plant Growth-Promoting Traits in Rhizobacteria of Heavy metal-Resistant Plants and Their Effects on Brassica nigra Seed Germination

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Pedosphere 2017年第3期27卷 511-526页

作者： Brenda ROmn-POnCE Diana miryel REZA-VZQUEZ Sonia GUTIRREZ-PAREDES maría de Jesús DE HARO-CRUZ Jessica mALDOnADO-hernnDEZ Yanely BAHEnA-OSORIO Paulina ESTRADA-DE LOS SAnTOS En Tao WAnG maría Soledad VSQUEZ-mURRIETA Instituto Politécnico nacional Escuela Nacional de Ciencias Biológicas Prolongación Carpio y Plan de Ayala s/n Col.Santo Tomás Del.Miguel Hidalgo Ciudad de México

Phytoremediation is an emerging technology that uses plants and their associated microbes to clean up pollutants from the soil, water, and air. In order to select the plant growth-promoting rhizobacteria （PGPR） for phytoremediation of heavy metal contamination, 60 bacterial strains were isolated from the rhizosphere of two endemic plants, Prosopis laevigata and Spharealcea angustifolia, in a heavy metal-contaminated zone in mexico. These rhizobacterial strains were characterized for the growth at different pH and salinity, extracellular enzyme production, solubilization of phosphate, heavy metal resistance, and plant growth-promoting （PGP） traits, including production of siderophores and indol-3-acetic acid （IAA）. Overall, the obtained rhizobacteria presented multiple PGP traits. These rhizoba^teria were also resistant to high levels of heavy metals （including As as a metalloid）（up to 480 mmol L-1 As（V）, 24 mmol L-1 Pb（II）, 21 mmol L-1 Cu（II）, and 4.5 mmol L-1 Zn（II））. Seven rhizobacterial strains with the best PGP traits were identified as members of Alcaligenes, Bacillus, Curtobacterium, and microbacterium, and were selected for further bioassay. The inoculation of Brassica nigra seeds with microbacteriurn sp. CE3R2, microbacterium sp. nE1R5, Curtobacterium sp. nm1R1, and microbacterium sp. nm3E9 facilitated the root development; they significantly improved the B. nigra seed germination and root growth in the presence of heavy metals such as 2.2 mmol L-1 Zn（II）. The rhizobacterial strains isolated in the present study had the potential to be used as efficient bioinoculants in phytorremediation of soils contaminated with multiple heavy metals.

关键词： bioinoculants endemic plants mine railings pH phytoremediation salinity

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Evaluation of Stress Corrosion Cracking Damage to an API 5L X52 Pipeline Transporting Ammonia: A Case Study

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materials Sciences and Applications 2016年第10期7卷 610-622页

作者： José Luis mora-mendoza mónica Jazmín hernández-Gayosso Daniel Antonio morales-Serrat Octaviano Roque-Oms Digna Alejandra Del Angel Gerardo Zavala-Olivares Petróleos mexicanos Marina Nacional 329 Col. Petróleos Mexicanos CDMX Ciudad de México México Instituto mexicano del Petróleo Eje Central Lázaro Cárdenas Norte 152 Col. San Bartolo Atepehuacan CDMX Ciudad de México México

The high number of leak events that took place in recent years at a 25.4 cm (10”)Øpipeline transporting anhydrous liquid ammonia, located in the Southeast of mexico, was the main reason to carry out a number of field studies and laboratory tests that helped establish not only the failure causes but also mitigation and control solutions. The performed activities included direct evaluation at failure sites, total repair programs, metallographic studies and pipeline flexibility analyses. The obtained results were useful to conclude that the failures obeyed a cracking mechanism by Stress Corrosion Cracking (SCC) which was caused by the combined effect of different factors: high stress resistance, high hardness of the base metal with a microstructure prone to brittleness and residual strains originated during the pipeline construction. From the operative, logistic and financial standpoints, it is not feasible to release the stress of approximately 22 km of pipeline. Therefore, the only viable solution is to install a new pipeline with suitable fabrication, construction and installation specifications aimed at preventing the SCC phenomenon.

关键词： Stress Corrosion Cracking Residual Stress Ammonia Transporting Pipeline

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A system for calculating the merchantable volume of oak trees in the northwest of the state of Chihuahua, mexico

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Journal of Forestry Research 2009年第4期20卷 293-300,I0004页

作者： marín POmPA-GARCíA José Javier CORRAL-RIVAS José Ciro hernánDEZ-DíAZ Juan Gabriel ALVAREZ-GOnZáLEZ Universidad Juárez del Estado de Durango Río Papaloapan y Blvd. Durango S/N Col. Valle del Sur Instituto de Silvicultura e Industria de la madera. Universidad Juárez del Estado de Durango. Km 5.5 Carretera a Mazatlán Departamento de Ingeniería Agroforestal Universidad de Santiago de Compostela. Escuela Politécnica Superior Campus universitario

The taper functions of Kozak （1988）, Bi （2000） and Fang et al. （2000） were comparatively analyzed in the present paper to develop a system for calculating the merchantable volume of oaks in the northwestern region of the state of Chihuahua （mexico）. Taper data corresponding to 298 trees were collected in mixed and uneven-aged pine-oak stands located throughout the study area, and covering the cxisting range of ages, stand densities and sites. Results show that the compatible segmented model developed by Fang et al. （2000） best described the experimental data and is therefore recommended for estimating tree diameter at a specific height, height to a specific diameter, merchantable volume, and total volume for oaks. The equation developed in this study is a fundamental tool for use in forest surveys in the study region and is simple enough to ensure its operational implementation. The results of the statistical analysis show that the equation can be recommended for other regions, although some local adaptations may be needed.

关键词： commercial volume Quercus taper function variable inflexion point

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Effect of human disturbance on the structure and regeneration of forests in the nevado de Toluca national Park, mexico

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Journal of Forestry Research 2012年第1期23卷 39-44页

作者： Angel Rolando Endara Agramont Sergio Franco maass Gabino nava Bernal Juan Ignacio Valdez hernández Todd S.Fredericksen Instituto de Ciencias Agropecuarias y Rurales(ICAR) Universidad Autónoma del Estado de MéxicoInstituto Literario N°100Col.Centro.PO.Box 50000.TolucaMéxico colegio de Posgraduados Carretera México-TexcocoKm.36.5Montecillo.PO.Box 56230TexcocoMéxico School of natural Sciences and mathematics Ferrum CollegeP.O.Box 1000Ferrum VA 24088USA

Sample plots were established in the principal forest types in the the nevado de Toluca national Park, mexico including those domi- nated by Pinus hartwegii, Abies religiosa, Quercus laurina and Alnus jorullensis. The vertical structure was defined by three strata in the coniferous forests and two strata in the broadleaved forests. Timber harvesting in Abies religiosa and Quercus laurina forests and fires generated by humans in Pinus hartwegii forests impeded the recruitment of saplings. mature trees were also heavily impacted by logging in Pinus hartwegii forests. On the contrary, Alnusjorullensis forests were increas- ing due to the disturbance of Pinus and Quercus forests, as well aban- doned crop lands within the park. A combination of logging, uncon- trolled fire, and grazing appears to be compromising the recruitment of important tree species in this national park. These factors, together with human settlements, have also increased the proportion of early succes- sional species. Changes in forest structure from human disturbance indicate a need to control these activities if conservation goals are not to be compromised.

关键词： forest structure human disturbance mountain forests

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Effect of tibolone pretreatment on kinases and phosphatases that regulate the expression and phosphorylation of Tau in the hippocampus of rats exposed to ozone

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neural Regeneration Research 2018年第3期13卷 440-448页

作者： Rodolfo Pinto-Almazán Julia J. Segura-Uribe marvin A. Soriano-Ursúa Eunice D. Farfán-García Juan m. Gallardo Christian Guerra-Araiza Unidad de Investigación Hospital Regional de Alta Especialidad Ixtapaluca Carretera Federal México-Puebla km 34.5 C.P. 56530. Ixtapaluca State of Mexico Mexico Institute for the Developing mind Children's Hospital Los Angeles Los Angeles CA USA Department of Pediatrics Keck School of Medicine University of Southern California Los Angeles CA USA Unidad de Investigación médica en Enfermedades neurológicas Hospital de Especialidades Centro Médico Nacional Siglo XXI Instituto Mexicano del Seguro Social Av. Cuauhtémoc 330 Col. Doctores. C. P. 06720. Mexico City Mexico Escuela Superior de medicina Instituto Politécnico Nacional Plan de San Luis y Diaz Mirón Col. Casco de Santo Tomis. C. P. 11340. Mexico City Mexico Unidad de Investigación médica en Enfermedades nefrológicas Hospital de Especialidades Centro Médico Nacional Siglo XXI Instituto Mexicano del Seguro Social Av. Cuauhtémoc 330 Col. Doctores. C. P. 06720. Mexico City Mexico Unidad de Investigación médica en Farmacologia Hospital de Especialidades Centro Médico Nacional Siglo XXI Instituto Mexicano del Seguro Social Av. Cuauhtémoc 330 Col. Doctores. C. P. 06720. Mexico City Mexico

Oxidative stress （OS） is a key process in the development of many neurodegenerative diseases, memory disorders, and other pathological processes related to aging. Tibolone （TIB）, a synthetic hormone used as a treatment for menopausal ymptoms, decreases lipoperoxidation levels, prevents memory impairment and learning disability caused by ozone （O3） exposure. However, it is not clear if TIB could prevent the increase in phosphorylation induced by oxidative stress of the microtubule-associated protein Tau. In this study, the effects of TIB at different times of administration on the phosphorylation of Tau, the activation of glycogen synthase kinase-3β （GSK3β）, and the inactivation of Akt and phosphatases PP2A and PTEn induced by O3 exposure were assessed in adult male Wistar rats. Rats were divided into 10 groups： control group （ozone-free air plus vehicle [C]）, control ＋ TIB group （ozone-free air plus TIB 1 mg/kg [C ＋ TIB]）; 7,15, 30, and 60 days of ozone exposure groups [O3] and 7, 15, 30, and 60 days of TIB 1 mg/kg before ozone exposure groups [O3 ＋ TIB]. The effects of O3 exposure and TIB administration were assessed by western blot analysis of total and phosphorylated Tau, GSK3β, Akt, PP2A, and PTEn proteins and oxidative stress marker nitrotyrosine, and superoxide dismutase activity and lipid peroxidation of malondialdehyde by two different spectrophotometric methods （marklund and TBARS, respectively）. We observed that O3 exposure increases Tau phosphorylation, which is correlated with decreased PP2A and PTEn protein levels, diminished Akt protein levels, and increased GSK3β protein levels in the hippocampus of adult male rats. The effects of O3 exposure were prevented by the long-term treatment （over 15 days） with TIB. malondialdehyde and nitrotyrosine levels increased from 15 to 60 days of exposure to O3 in comparison to C group, and superoxide dismutase activity decreased. Furthermore, TIB administration limited the changes induced by O3 exposure. Our results

关键词： tibolone oxidative stress ozone exposure Tau GSK3 hippocampus neuroprotection

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