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The Influence of the Precipitation Heat Treatment Temperature on the Metallurgical, Microstructure, Thermal Properties, and Microhardness of an Alpha Brass

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Materials Sciences and Applications 2018年第4期9卷 440-454页

作者： Ignacio Rojas-Rodríguez Alberto Lara-Guevara Mauricio Salazar-Sicacha Julio Cesar Mosquera-Mosquera Minerva Robles-Agudo Cristian Ramirez-Gutierrez Mario Rodríguez-García División Industrial Universidad Tecnológica de Querétaro Querétaro México División de Posgrado Facultad de Informática Universidad Autónoma de Querétaro Querétaro México Programa de Física Universidad del Quindío Armenia Colombia Catedras Conacyt Universidad Tecnológica de Querétaro Querétaro México Posgrado en ciencia e ingeniería de Materiales Centro de Física Aplicada y Tecnología Avanzada Universidad Nacional Autónoma De México Campus Juriquilla Querétaro México departamento de nanotecnología Centro de Física Aplicada y Tecnología Avanzada Universidad Nacional Autónoma de México Campus Juriquilla Querétaro México

Metals obtain optimum conditions of metallurgical and physical properties through a heat treatment. Brass is one of the copper alloys which has many applications in everyday life and in the industry. Brass is one of the copper alloys which has many applications in everyday life and the industry. In this work, the influence of the precipitation heat treatment temperature on the metallurgical microstructure, structure, thermal properties, and microhardness of an alpha brass is analyzed. Samples were heat treated by precipitation for 2 h at 300°C, 400°C, 500°C, 600°C, and 700°C. The best mechanical properties were found at 500°C of precipitation heat treatment temperature. Specimens were characterized by scanning electron microscopy, X-ray diffraction, Vickers microhardness, photothermal radiometry, and photoacoustic to study the thermal diffusivity and conductivity, as well as the heat capacity. The inverse of the full width at the half maximum analysis showed that the crystallinity decreased as the precipitation heat treatment temperature increased. Metallurgical microstructure and microhardness were correlated to the precipitation heat treatment temperatures to determine the effect on the metallurgical and mechanical properties, as well as the effect on the thermal properties of alpha brass.

关键词： Alpha Brass Kunial Brass Crystallinity Photoacoustic Precipitation Heat Treatment X Ray Diffraction

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Preferential Transport and Metabolism of Glucose in Bergmann Glia over Purkinje Cells:A Multiphoton Study of Cerebellar Slices

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神经损伤与功能重建 2009年第3期4卷 208-216页

作者： L.F.BARROS R.COURJARET P.JAKOBy A.LOAIZA C.LOHR J.W.deITMER centro de Estudios Científicos (CECS) CIn(centro de ingeniería de la Innovación del CECS) Abteilung für Allgemeine Zoologie Fachbaraich BiologieTU Kaiserslautern Universidad Austral de Chile

了解不同类型的细胞如何处理葡萄糖有助于解释能量供应是如何是如何根据大脑能量需求来进行调整的。荧光追踪结合共聚焦显微镜技术已用于研究培养的脑细胞摄取葡萄糖的实时动态过程。本文采用这种技术利用多光子显微镜观察急性制备的大... 详细信息

了解不同类型的细胞如何处理葡萄糖有助于解释能量供应是如何是如何根据大脑能量需求来进行调整的。荧光追踪结合共聚焦显微镜技术已用于研究培养的脑细胞摄取葡萄糖的实时动态过程。本文采用这种技术利用多光子显微镜观察急性制备的大鼠小脑脑片。带荧光的葡萄糖类似物2nBDG和6nBDG在小脑皮质的分子层中的转运速度比其在蒲肯野细胞胞体和颗粒细胞中快若干倍。洗脱游离示踪剂后,可见大部分磷酸化示踪剂都位于Bergmann胶质细胞,用胶质细胞标记物sulforhodamine 101免疫染色后进一步确认这一结果。有效回收荧光光漂白后显示,2nBDG-P可通过Bergmann胶质细胞之间的缝隙连接沿着分子层水平扩散。本文的结果表明在急性小脑切片中,Bergmann胶质细胞对葡萄糖的转运能力和糖酵解率高于蒲肯野细胞若干倍。由于小脑主要由葡萄糖提供能量,蒲肯野神经元被认为比Bergmann胶质细胞更耗能量,这些结果表明,在胶质细胞和神经元之间存在类似乳酸的能量代谢物介导的环路。

关键词：脑片小脑葡萄糖 nBDG 转运己糖激酶

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Analysing changes in spatial point patterns:A proposal using data from a forest thinning experiment

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Forest Ecosystems 2022年第6期9卷 878-887页

作者： Christian Salas-Eljatib Joaquín Riquelme-Alarcon Pablo J.Donoso Diego Ponce Daniel P.Soto centro de Modelacion y Monitoreo de Ecosistemas Escuela de Ingeniería ForestalUniversidad MayorSantiagoChile Vicerrectoría de investigacion y Postgrado Universidad de La FronteraTemucoChile departamento de Silvicultura y Conservacion de la naturaleza Universidad de ChileSantiagoChile Instituto de Bosques y Sociedad Universidad Austral de ChileValdiviaChile Corporacion nacional Forestal ValdiviaChile departamento de ciencias naturales y Tecnología Universidad de AysenCoyhaiqueChile

Spatial patterns reveal critical features at the individual and community ***,how to evaluate changes in spatial characteristics remains largely *** assess spatial changes in spatial point patterns by augmenting current statistical functions and *** fitted functions to describe unmarked and marked(tree size)spatial patterns using data from a large-scale silvicultural experiment in southern ***,we compute the mingling index to represent spatial tree *** proffer the pair correlation function difference before and after treatment to detect changes in the unmarked-point pattern of trees and the semivariogram-ratio to evaluate changes in the marked-point *** research provides a quantitative assessment of a critical aspect of forest heterogeneity:changes in spatial unmarked and marked-point *** proposed approach can be a powerful tool for quantifying the impacts of disturbances and silvicultural treatments on spatial patterns in forest ecosystems.

关键词： Spatial diversity Marked-point process Spatial heterogeneity Conspecific Variable-density thinning nothofagus

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Effect of the Substitution of Sand by Rubber of Waste Tires on the Mechanical Properties of Hydraulic Concrete and Exposure to Gamma Radiation

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Journal of Minerals and Materials Characterization and Engineering 2021年第3期9卷 245-256页

作者： Jesús M. Colín de la Cruz Carmen Gabriela Guzmán Fermín Castillo Mejía Benjamin Leal Acevedo Osvaldo Flores Cedillo Isabel Gamboa de Buen Arturo Molina Ocampo Horacio Martínez Valencia Facultad de ciencias Químicas e ingeniería Universidad Autónoma del Estado de Morelos Cuernavaca México Laboratorio de Espectroscopia Instituto de Ciencias Físicas Universidad Nacional Autónoma de México Cuernavaca México Instituto de ciencias nucleares Universidad Nacional Autónoma de México México City México centro de investigación en ingeniería y ciencias aplicadas UAEM Cuernavaca México

For a long time and until now, rubber is the most used material for the manufacture of tires for motor vehicles. Unfortunately, once the tire meets its life cycle, the remaining rubber cannot be recycled, so the tires are discarded in collection centers and often in clandestine dumps. This represents a serious environmental problem because, in one case, these waste tires become breeding grounds for insects and wildlife that is harmful to humans. In the second case, the tires are burned, releasing highly damaging gases into the atmosphere. On the other hand, concrete is worldwide the construction material par excellence. It is basically composed of cement, gravel and sand. Mixing these three components in different proportions, their mechanical strength in compression can be increased. However, due to its fragile nature, concrete, once a crack is formed, it rapidly advances by fragmenting the material and producing its rapid collapse. In the present work, in order contribute to the care of the environment as well as to modify the fracture mode of the concrete, rubber particles obtained from waste tires were used as sand substitute in hydraulic concrete. In addition, rubber modified samples concrete were lately exposed to 70 kGy of gamma radiation in order to study the effects of this radiation on the mechanical deformation of concrete. The results showed a decrease in the mechanical properties of the concrete with rubber particles with respect to the traditional concrete itself. However, such decreases were offset by the fact that samples with rubber addition do not collapses as fast as the free rubber samples. The acquired data pave the way for research with great benefits, such as the use of recycled tires in concrete for its fracture mode modification in a beneficial way, as well as a possible decrease in the cost of concrete.

关键词： Hydraulic Concrete Scrap Tire Rubber Strength Gamma Radiation Mechanical Properties

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Two-Dimensional Continuous Model in Bimolecular Reactive Transport

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Open Journal of Fluid Dynamics 2023年第1期13卷 47-60页

作者： Daniel A. Cuch Diana Rubio Claudio D. El Hasi Instituto de ciencias Universidad Nacional de General Sarmiento Buenos Aires Argentina ITECA (COnICET-UnSAM)-centro de Matemática aplicada ECyT-Universidad Nacional de San Martín Buenos Aires Argentina departamento de ciencias Básicas Facultad de Ingeniería Universidad Argentina de la Empresa Buenos Aires Argentina

In this work, a continuum 2D model is proposed to study the interaction at the interface of reactive transport processes in porous media. The analysis of the segregation produced by poor reactant homogenization at the poral scale is addressed by a parametric heuristic model that considers the relative gradient of the reacting species involved in the process. The micro inhomogeneities are incorporated by means of longitudinal and transversal mechanical dispersion coefficients. A two-dimensional continuous model for the bimolecular reactive transport is considered where modelling parameters are estimated numerically from experimental data. A competitive effect between segregation and dispersion is observed that is analyzed by means of numerical experiments. The two-dimensional model reproduces properly both the total mass of the product as well as its increase with the velocity of flow and the inhomogeneity of the advanced front. The methodology used is simple and fast, and the numerical results presented here indicate its effectiveness.

关键词： Bidimensional Model Transverse Dispersion Segregation Parameter Estimation

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nonlinear optical properties in n-type quadrupleδ-doped GaAs quantum wells

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Chinese Physics B 2022年第4期31卷 348-351页

作者： Humberto noverola-Gamas Luis Manuel Gaggero-Sager Outmane Oubram Division Academica de ingenierıa y Arquitectura Universidad Juarez Autonoma de TabascoCarretera Cunduacan-Jalpa de Mendez Km.1 Col.La EsmeraldaCunduacan8660Mexico centro de investigacion en ingenierıa y ciencias aplicadas Universidad Autonoma del Estado de MorelosAv.Universidad 1001 Col.ChamilpaCuernavaca62209Mexico Facultad de ciencias Quımicas e ingenierıa Universidad Autonoma del Estado de MorelosAv.Universidad 1001 Col.ChamilpaCuernavaca62209Mexico

The effects of the interlayer distance on the nonlinear optical properties of n-type quadrupleδ-doped GaAs quantum well were theoretically ***,the absorption coefficient and the relative refraction index change were *** the effective mass approach and within the framework of the Thomas-Fermi theory,the Schrodinger equation was ***,the subband energy levels and their respective wave functions were *** variations in the nonlinear optical properties were determined by using the density matrix *** achieved results demonstrate that the interlayer distance causes optical red-shift on nonlinear optical ***,it can be deduced that the suitably chosen interlayer distance can be used to tune optical properties within the infrared spectrum region in optoelectronic devices such as far-infrared photo-detectors,high-speed electronic-optical modulators,and infrared lasers.

关键词： delta-doping n-type GaAs layers electronic structure non-linear optical properties

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Health Risk Assessment in Children by Arsenic and Mercury Pollution of Groundwater in a Mining Area in Sonora, Mexico

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Journal of Geoscience and Environment Protection 2019年第6期7卷 90-105页

作者： José Leopoldo Mendoza-Lagunas Diana María Meza-Figueroa Marco Antonio Martínez-Cinco Mary Kay O’Rourke Elena Centeno-García Francisco Martin Romero Leticia García-Rico María Mercedes Meza-Montenegro Programa de Doctorado en ciencias en Biotecnologia Instituto Tecnológico de Sonora Ciudad Obregón México División de ciencias Exactas y naturales Departamento de Geología Universidad de Sonora Rosales y Encinas Hermosillo México División de Estudios de Posgrado Facultad de Ingeniería Química Universidad Michoacana de San Nicolás de Hidalgo (UMSNH) Morelia México Mel & Zuckerman College of Public Health University of Arizona Tucson AZ USA Instituto de Geología Universidad Nacional Autónoma de México Ciudad Universitaria Delegación Coyoacán Ciudad de México México centro de investigación en Alimentos y desarrollo Hermosillo México Dirección de Recursos naturales InstitutoTecnológico de Sonora Obregón México

A highly acidic spill from one of the most important copper mines in the Americas (Buenavista del Cobre) occurred in Sonora, Mexico in August, 2014. 40,000 m3 of metals-enriched sulphate solution escaped into the Sonora River representing the worst ecological disaster in Mexican history. The spill affected the economy, water accessibility and the health of residents near the river. despite the economic importance of mining in this area, no environmental assessment was undertaken. There is no information about the health impact of this event on the local population. The study assesses the health risk among children exposed to arsenic and mercury via groundwater in five communities located in a mining area into the Sonora River Basin, Mexico. Local drinking water from the localities was sampled one year after the spill and it was analyzed for arsenic and mercury by Atomic Absorption Spectrometry coupled with Hydride Generation (AAS/HG). Further, some of the traditional local foods were sampled and analyzed for the same elements. Results indicate that levels of arsenic in drinking water did not exceed the Mexican norm (25 μg As/L) or the EPA Guideline (10 μg As/L). The concentrations of mercury exceeded the WHO and Mexican Legislation value (1.0 μg Hg/L). The Hazard Quotient (HQ) values for arsenic were >1 in 42% of children exposed and for mercury in 67% of the children. Foods concentrations contained in the ranges of 9.2 to 62.0 μg As/Kg and 0.28 to 42 μg Hg/Kg for arsenic and mercury respectively. These values are below the Codex Alimentarius limits. Children affected by mining activities are at risk of developing chronic diseases associated with low arsenic and mercury exposure via groundwater consumption, without consideration of the contribution from these metals by other important exposures routes.

关键词： Hazard Quotient Mining Mercury Arsenic Children

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Benzyl Amino Purine and Gibberellic Acid Coupled to nitrogen-Limited Stress Induce Fatty Acids,Biomass Accumulation,and Gene Expression in Scenedesmus Obliquus

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Phyton-International Journal of Experimental Botany 2021年第2期90卷 515-531页

作者： Hans Christian Correa-Aguado Gloria Viviana Cerrillo-Rojas Alejandro Rocha-Uribe Ruth Elena Soria-Guerra JoséFrancisco Morales-Domínguez departamento de Química Centro de Ciencias BásicasUniversidad Autónoma de AguascalientesAguascalientes20131México Facultad de ciencias Químicas Universidad Autónoma de San Luis PotosíSan Luis Potosí78210México Instituto Politécnico nacional Unidad Profesional Interdisciplinaria de Ingeniería Campus ZacatecasBlvd.del Bote 202Cerro del Gato Ejido La EscondidaCol.Ciudad AdministrativaZacatecasZAC 98160Mexico

The need for renewable energy sources makes microalgae an essential feedstock for biofuels *** molecular aspects and the response to nitrogen(n)-limited conditions with a phytohormone stimulus in microalgae have been slightly *** this work,Scenedesmus obliquus was used as a study model to analyze the effect of benzyl amino purine(BAP)and gibberellic acid(GA)coupled to nitrogen limitation on cell growth,biomass and fatty *** selected 10^(-5)M BAP increased the biomass by 1.44-fold,and 10^(-6)M GA by *** total lipids also increased by 2.8 and 1.11-fold,*** 10^(-5)M BAP and 10^(-6)M GA addition to *** cultures at different initial nitrogen percentages(n-0,n-25,and n-50)showed a significant increase in cell growth and biomass productivity compared to the unstimulated *** n-0 and GA n-0 produced the highest lipid yields with 55%and 50%,*** lipid profile analysis revealed an increase,particularly in C18:1 and C16:0 fatty *** expression analysis showed an over-expression of acyl carrying protein(ACP),stearoyl-ACP desaturase(SAD),fatty acid acyl-ACP thioesterase(FATA),and diacylglycerol acyltransferase(DGAT)genes,which were mainly induced by nitrogen ***,BAP and GA produced a significant over-expression on these genes in the n-replete *** study shows that BAP and GA,coupled to n limitation stress,can be used to increase the biomass and lipid production in *** for sustainable biofuels.

关键词： Biodiesel gene expression lipids microalgae nitrogen deficiency phytohormones

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Isolation and Characterization of Mercury Resistant Trichoderma Strains from Soil with High Levels of Mercury and Its Effects on Arabidopsis thaliana Mercury Uptake

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Advances in Microbiology 2018年第7期8卷 600-613页

作者： JoséLuis Hernández-Flores JoséGerardo Bernal Melo Andrés Cruz Hernández Miguel A.Ramos López Carlos Saldana Gutiérrez Sergio Romero Gomez Victor Pérez Moreno Rosa P.Calvillo Medina JoséHumberto Valenzuela Soto Sergio Pacheco Hernández George H.Jones Sergio Casas Flores Juan Campos-Guillen Laboratorio de Bioseguridad y Análisis de Riesgo Departamento de Ingeniería Genética de PlantasCentro de Investigación y de Estudios Avanzados del IPNIrapuatoGto.México Facultad de Química Universidad Autónoma de QuerétaroCerro de las Campanas s/nQuerétaroQro.México Escuela de Agronomía Universidad De La Salle Bajíocampus Campestre.LeónGto.México Facultad de ciencias naturales Universidad Autónoma de QuerétaroAv.De las Ciencias S/NQuerétaroQro.México centro de investigación en Química aplicada Blvd.Enrique Reyna Hermosillo No.140SaltilloCoahuilaMéxico department of Biology Emory UniversityAtlantaGeorgiaUSA IPICyT División de Biología Molecular.Camino a la presa San JoséNo.2055Colonia Lomas 4a sección.C.P.San Luis PotosíMexico

Traditional mining activities are usually correlated with high levels of soil pollution, which is a major environmental concern. Extensive mining activities have taken place in the San Joaquin region in the State of Querétaro, México resulting in high levels of mercury soil pollution (up to 1532 ± 300 mg/kg). We isolated mercury-resistant fungal strains from the San Joaquin region soils and identified them through morphologic characteristics and ITS rDnA region sequence analysis. We determined that fungi isolated belong to the genus Trichoderma. All the isolates selected showed the ability to catalyze the volatilization of Hg. For air sampling, an active sampling device was constructed and using acid KMnO4 as an absorbent, the concentration of mercury in solution was determined through the cold vapor atomic absorption method. The results show mercury volatilization from the fungal species assay, with a maximum of 213.04 ± 32.6 μg/m3 while mycelium accumulation ranged from less than 17.5 ± 2.9 to 20.0 ± 3.4 μg/g. The fungal isolates were also evaluated for their ability to reduce mercury uptake in Arabidopsis thaliana. These observations suggest the utility of Trichoderma for the mobilization of mercury in those contaminated soils.

关键词： Volatilization Mercury Trichoderma Soil Bioremediation

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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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