Micro-structural study and Rietveld analysis of fast reactor fuels: U–Mo fuels

International Nuclear Information System (INIS)

Chakraborty, S.; Choudhuri, G.; Banerjee, J.; Agarwal, Renu; Khan, K.B.; Kumar, Arun

2015-01-01

U–Mo alloys are the candidate fuels for both research reactors and fast breeder reactors. In-reactor performance of the fuel depends on the microstructural stability and thermal properties of the fuel. To improve the fuel performance, alloying elements viz. Zr, Mo, Nb, Ti and fissium are added in the fuel. The first reactor fuels are normally prepared by injection casting. The objective of this work is to compare microstructure, phase-fields and hardness of as-cast four different U–Mo alloy (2, 5, 10 and 33 at.% Mo) fuels with the equilibrium microstructure of the alloys. Scanning electron microscope with energy dispersive spectrometer and optical microscope have been used to characterize the morphology of the as-cast and annealed alloys. The monoclinic α'' phase in as-cast U-10 at.% Mo alloy has been characterized through Rietveld analysis. A comparison of metallographic and Rietveld analysis of as-cast (dendritic microstructure) and annealed U-33 at.% Mo alloy, corresponding to intermetallic compound, has been reported here for the first time. This study will provide in depth understanding of microstructural and phase evolution of U–Mo alloys as fast reactor fuel. - Highlights: • U–Mo alloys in as-cast as well as in annealed conditions have been studied using Optical Microscope, SEM, XRD. • The monoclinic α'' phase in as-cast U-10 at.% Mo alloy has been characterized through Rietveld analysis. • The dendritic microstructure of γ-(U,Mo) and B.C.C. ‘Mo’ phase of 33 at.% U–Mo alloy have been analysed. • Rietveld analysis has been done to optimize lattice parameters and calculate phase fractions in annealed alloys. • The Vickers microhardness of U_2Mo phase shows lower hardness than two phase microstructures in annealed alloys.

Micro-structural study and Rietveld analysis of fast reactor fuels: U–Mo fuels

Energy Technology Data Exchange (ETDEWEB)

Chakraborty, S., E-mail: sibasis@barc.gov.in [Radiometallurgy Division, Bhabha Atomic Research Centre, Mumbai, 400085 (India); Choudhuri, G. [Atomic Fuels Division, Bhabha Atomic Research Centre, Mumbai, 400085 (India); Banerjee, J. [Radiometallurgy Division, Bhabha Atomic Research Centre, Mumbai, 400085 (India); Agarwal, Renu [Product Development Division, Bhabha Atomic Research Centre, Mumbai, 400085 (India); Khan, K.B.; Kumar, Arun [Radiometallurgy Division, Bhabha Atomic Research Centre, Mumbai, 400085 (India)

2015-12-15

U–Mo alloys are the candidate fuels for both research reactors and fast breeder reactors. In-reactor performance of the fuel depends on the microstructural stability and thermal properties of the fuel. To improve the fuel performance, alloying elements viz. Zr, Mo, Nb, Ti and fissium are added in the fuel. The first reactor fuels are normally prepared by injection casting. The objective of this work is to compare microstructure, phase-fields and hardness of as-cast four different U–Mo alloy (2, 5, 10 and 33 at.% Mo) fuels with the equilibrium microstructure of the alloys. Scanning electron microscope with energy dispersive spectrometer and optical microscope have been used to characterize the morphology of the as-cast and annealed alloys. The monoclinic α'' phase in as-cast U-10 at.% Mo alloy has been characterized through Rietveld analysis. A comparison of metallographic and Rietveld analysis of as-cast (dendritic microstructure) and annealed U-33 at.% Mo alloy, corresponding to intermetallic compound, has been reported here for the first time. This study will provide in depth understanding of microstructural and phase evolution of U–Mo alloys as fast reactor fuel. - Highlights: • U–Mo alloys in as-cast as well as in annealed conditions have been studied using Optical Microscope, SEM, XRD. • The monoclinic α'' phase in as-cast U-10 at.% Mo alloy has been characterized through Rietveld analysis. • The dendritic microstructure of γ-(U,Mo) and B.C.C. ‘Mo’ phase of 33 at.% U–Mo alloy have been analysed. • Rietveld analysis has been done to optimize lattice parameters and calculate phase fractions in annealed alloys. • The Vickers microhardness of U{sub 2}Mo phase shows lower hardness than two phase microstructures in annealed alloys.

The Rietveld method applied to the quantitative mineralogical analysis of some soil samples from Argentina Aplicación del método de Rietveld al análisis mineral��gico cuantitativo de algunas muestras de suelos de la Argentina

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Stella M Zabala

2007-07-01

Full Text Available The mineralogical quantification of soils species is mainly obtained by analysis of X-ray diffraction (XRD patterns. The classic method, for these analyses, is limited to semi quantitative determinations due to the overlapping of different specie's peaks and processes of absorption of the constituents, the wide range of particle size distribution, etc. The use of the Rietveld method for XRD quantitative analysis, in mixtures of minerals, has allowed to improve the accuracy of the quantitative results and to extend it to complex systems, as soils, transforming it in a meaningful tool for soils investigation. In this work, quantitative results obtained by the application of classic and Rietveld methods, are compared in different soils samples from Argentina. A set of mixtures of minerals with similar composition to three studied samples, was also quantified by Rietveld method, with absolute error lower than 3%. Obtained results indicate that quantitative analysis by Rietveld method, can improve the results found by XRD classic method and may be used for the quantitative determination of soil minerals.La cuantificación mineralógica de componentes del suelo es obtenida principalmente por análisis de espectros de difracción de rayos X (DRX. El método clásico aplicado para dicho análisis está limitado a determinaciones semi-cuantitativas debido a la superposición de picos de las distintas especies y procesos de absorción de los constituyentes, el amplio rango de distribución de tamaño de partícula, etc. El uso del método de Rietveld para el análisis cuantitativo por DRX, en mezclas de minerales, ha permitido mejorar la exactitud de los resultados cuantitativos y extenderlo a sistemas complejos, como lo son los suelos, transformándose en una herramienta significativa para su investigación. En este trabajo se comparan los resultados cuantitativos obtenidos por la aplicación del método clásico y de Rietveld, a diferentes muestras de

Possibilities and limitations of parametric Rietveld refinement on high pressure data. The case study of LaFeO{sub 3}

Energy Technology Data Exchange (ETDEWEB)

Etter, Martin; Mueller, Melanie; Dinnebier, Robert E. [Max-Planck-Institut fuer Festkoerperforschung, Stuttgart (Germany); Hanfland, Michael [European Synchrotron Radiation Facility (ESRF), Grenoble (France)

2014-04-01

Parametric Rietveld refinement is a powerful technique to apply directly physical or empirical equations to the refinement of in situ powder diffraction data. In order to investigate the possibilities and limitations of parametric Rietveld refinements for high pressure data four competitive crystallographic approaches were used to carry out a full structural investigation of the orthoferrite LaFeO{sub 3} (Pbnm at ambient conditions) under high pressure up to 47 GPa. Approach A with traditional Rietveld refinement using atomic coordinates, Approach B where the Rietveld refinement was done by using the rigid body method, Approach C where symmetry modes were used and Approach D where the newly developed method of the rotational symmetry mode description for a rigid body was used. For all approaches sequential as well as parametric refinements were carried out, confirming a second order phase transition of LaFeO{sub 3} to a higher symmetric phase (space group Ibmm) at around 21.1?GPa and an isostructural first order phase transition at around 38 GPa. Limitations due to non-hydrostatic conditions as well as the possibilities of a direct modeling of phase transitions with parametric Rietveld refinement are discussed in detail. (orig.)

Estilos de liderança de professores: aplicando o modelo de estilos parentais

Directory of Open Access Journals (Sweden)

Ana Priscila Batista

Full Text Available Professores orientam os comportamentos das crianças estabelecendo diferentes climas emocionais no uso das estratégias educativas em sala de aula. Esse trabalho busca delinear uma análise dos estilos de liderança de professores aplicando o modelo de estilos parentais. Inicialmente, foi feita uma análise de literatura realizando uma busca nas bases de dados: Scielo, Science Direct e Scopus, utilizando os descritores: teachers' leadership styles, teachers' teaching styles e school leadership. Com essa busca constatou-se que existem diversas definições, formas de análise e variáveis estudadas, conforme a teoria adotada. Posteriormente, foi realizada a análise da relação professor-aluno aplicando o modelo de estilos parentais, que apresenta uma análise do sistema das relações a partir de duas dimensões: responsividade e exigência. Assim, foram categorizados quatro estilos de liderança: autoritário, permissivo, negligente e participativo. Conclui-se que o modelo de estilo parental fornece uma boa base teórica para pautar a análise dos estilos de liderança de professores.

Determination of Cation Distributions in Mineral Structures by use of the Rietveld Full-Profile Refinement Technique

International Nuclear Information System (INIS)

Nord, A.G.

1986-01-01

Use of the Rietveld full-profile refinement technique with X-ray or neutron powder diffraction data for the determination of divalent-metal cation distributions in three mineral structure types (farringtonite, grafonite, sarcopside) is demonstrated. The accuracy of the conventional cation distribution coefficient Ksub(D) is about 5-10 percent with 24-46 parameters to be refined, and the averaged metal-oxygen distances are reliable and well correlated to the observed cation distribution pattern. In particular the usefulness of the Rietveld technique in combination with Moessbauer spectroscopy is stressed. Some concluding remarks are also given

Characterization of barium titanate powder doped with sodium and potassium ions by using Rietveld refining; Caracterizacao do po de titanato de bario dopado com ions sodio e potasio com o refinamento de Rietveld

Energy Technology Data Exchange (ETDEWEB)

Andrade, M.C.; Assis, J.T.; Pereira, F.R., E-mail: mcalixto@iprj.uerj.b [Universidade do Estado do Rio de Janeiro (IPRJ/UERJ), Nova Friburgo, RJ (Brazil). Instituto Politecnico; Araujo, J.C. [Universidade do Estado do Rio de Janeiro (FFP/UERJ), Sao Goncalo, RJ (Brazil). Fac. de Formacao de Professores; Moreira, E.L.; Moraes, V.C.A.; Lopes, A.R. [Centro Brasileiro de Pesquisas Fisicas (CBPF/MCT), Rio de Janeiro, RJ (Brazil)

2009-07-01

A solid-reaction synthesis of doped barium titanate was done by employing barium carbonates, sodium, potassium and titanium oxides with classic procedures. Rietveld refining of X ray diffraction data of perovskite samples with tetragonal symmetry was applying and show good agreement. Besides, the treatment performed from 600 deg C produces nanocrystals of barium titanate with average size of 33 nm. The presence of endothermic peaks related to BaTiO{sub 3} formation at relatively low temperatures was determined by thermal analysis. A pseudo-Voigt Thompson-Cox-Hastings function was used to fit the standard samples of barium titanate. The Rietveld method has showed be efficient to detect the influences of temperature and doping on barium titanate microstructures. (author)

Study the oxidation kinetics of uranium using XRD and Rietveld method

Science.gov (United States)

Zhang, Yanzhi; Guan, Weijun; Wang, Qinguo; Wang, Xiaolin; Lai, Xinchun; Shuai, Maobing

2010-03-01

The surface oxidation of uranium metal has been studied by X-ray diffraction (XRD) and Rietveld method in the range of 50~300°C in air. The oxidation processes are analyzed by XRD to determine the extent of surface oxidation and the oxide structure. The dynamics expression for the formation of UO2 was derived. At the beginning, the dynamic expression was nonlinear, but switched to linear subsequently for uranium in air and humid oxygen. That is, the growth kinetics of UO2 can be divided into two stages: nonlinear portion and linear portion. Using the kinetic data of linear portion, the activation energy of reaction between uranium and air was calculated about 46.0 kJ/mol. However the content of oxide as a function of time was linear in humid helium ambience. Contrast the dynamics results, it prove that the absence of oxygen would accelerate the corrosion rate of uranium in the humid gas. We can find that the XRD and Rietveld method are a useful convenient method to estimate the kinetics and thermodynamics of solid-gas reaction.

Characterization of barium titanate powder doped with sodium and potassium ions by using Rietveld refining

International Nuclear Information System (INIS)

Andrade, M.C.; Assis, J.T.; Pereira, F.R.

2009-01-01

A solid-reaction synthesis of doped barium titanate was done by employing barium carbonates, sodium, potassium and titanium oxides with classic procedures. Rietveld refining of X ray diffraction data of perovskite samples with tetragonal symmetry was applying and show good agreement. Besides, the treatment performed from 600 deg C produces nanocrystals of barium titanate with average size of 33 nm. The presence of endothermic peaks related to BaTiO 3 formation at relatively low temperatures was determined by thermal analysis. A pseudo-Voigt Thompson-Cox-Hastings function was used to fit the standard samples of barium titanate. The Rietveld method has showed be efficient to detect the influences of temperature and doping on barium titanate microstructures. (author)

Application of the Rietveld method to assess chromium(VI) speciation in chromite ore processing residue

International Nuclear Information System (INIS)

Chrysochoou, Maria; Dermatas, Dimitris

2007-01-01

The Rietveld method allows the quantification of crystalline phases and amorphous material identified by X-ray powder diffraction (XRPD) and other diffraction methods. The method assists in determining the speciation of contaminants in solid matrices both qualitatively and quantitatively in a statistically defensible approach, as it does not focus on a microscale. Rietveld was applied to chromite ore processing residue (COPR), a cementitious waste containing hexavalent chromium. Calcium aluminum chromium oxide hydrates (CACs) were the crystalline phases identified by XRPD that bind Cr 6+ in COPR according to their chemical formula. Rietveld quantification, combined with mass balances on Cr 6+ , showed that CACs may bind Cr 6+ in variable percentages, ranging from 25% to 85%. Analysis of duplicate samples showed that material variability is the predominant factor of uncertainty in evaluating the role of CACs in Cr 6+ speciation, provided that a consistent quantification strategy is pursued. The choice of strategy was performed on the basis of the pertinent literature, preliminary analyses of the equipment and the software settings, and mass balances. The correlation between the average CAC-bound Cr 6+ concentration and the total Cr 6+ for five samples (R 2 = 0.94), extracted from different zones and soil borings, suggests that CACs are a primary sink for Cr 6+ in COPR

Profile agreement indices in Rietveld and pattern-fitting analysis

International Nuclear Information System (INIS)

Hill, R.J.; Fischer, R.X.

1990-01-01

Two definitions of profile agreement indices are now in common use for estimating the degree of fit in Rietveld refinement and in structure-independent pattern-fitting methods of powder diffraction analysis. In the original program written by Rietveld, the background was subtracted and the 'non-peak' regions of the pattern were removed from further consideration in a preliminary data-reduction stage prior to structure refinement. However, the agreement indices used in many of the more recent programs retain the background counts in the observed step intensities and include all portions of the pattern in the sums. These latter definitions are strongly dependent on the signal-to-noise ratio and on the relative amount of 'background-only' regions and do not, therefore, provide a sound basis for comparing the degree of fit of peak profile and crystal structure model refinements in the general case. The extent of this dependence is illustrated quantitatively using conventional and synchrotron X-ray and constant-wavelength and time-of-flight neutron data sets with different inherent background levels and peak densities. The unweighted background-corrected peak-only profile agreement index R' p =Σ i vertical strokeY io -Y ic vertical stroke/Σ i vertical strokeY io -Y ib vertical stroke (and, to a lesser extent, its weighted equivalent) is recommended as the most appropriate criterion of fit for comparative work between diffraction patterns of all kinds. (orig.)

Study the oxidation kinetics of uranium using XRD and Rietveld method

Energy Technology Data Exchange (ETDEWEB)

Zhang Yanzhi; Guan Weijun; Wang Qinguo; Wang Xiaolin; Lai Xinchun; Shuai Maobing, E-mail: yanzhizh@163.com [China Academy of Engineering Physics, PO Box 919-71, Mianyang, Sichuan, 621900 (China)

2010-03-15

The surface oxidation of uranium metal has been studied by X-ray diffraction (XRD) and Rietveld method in the range of 50{approx}300deg. C in air. The oxidation processes are analyzed by XRD to determine the extent of surface oxidation and the oxide structure. The dynamics expression for the formation of UO{sub 2} was derived. At the beginning, the dynamic expression was nonlinear, but switched to linear subsequently for uranium in air and humid oxygen. That is, the growth kinetics of UO{sub 2} can be divided into two stages: nonlinear portion and linear portion. Using the kinetic data of linear portion, the activation energy of reaction between uranium and air was calculated about 46.0 kJ/mol. However the content of oxide as a function of time was linear in humid helium ambience. Contrast the dynamics results, it prove that the absence of oxygen would accelerate the corrosion rate of uranium in the humid gas. We can find that the XRD and Rietveld method are a useful convenient method to estimate the kinetics and thermodynamics of solid-gas reaction.

Tailoring diffraction technique Rietveld method on residual stress measurements of cold-can oiled 304 stainless steel plates

International Nuclear Information System (INIS)

Parikin; Killen, P.; Anis, M.

2003-01-01

Tailoring of diffraction technique-Rietveld method on residual stress measurements of cold-canailed stainless steel 304 plates assuming the material is isotopic, the residual stress measurements using X-ray powder diffraction is just performed for a plane lying in a large angle. For anisotropic materials, the real measurements will not be represented by the methods. By Utilizing of all diffraction peaks in the observation region, tailoring diffraction technique-Rietveld analysis is able to cover the limitations. The residual stress measurement using X-ray powder diffraction tailored by Rietveld method, in a series of cold-canailed stainless steel 304 plates deforming; 0, 34, 84, 152, 158, 175, and 196 % reduction in thickness, have been reported. The diffraction data were analyzed by using Rietveld structure refinement method. Also, for all cold-canailed stainless steel 304 plates cuplikans, the diffraction peaks are broader than the uncanailed one, indicating that the strains in these cuplikans are inhomogeneous. From an analysis of the refined peak shape parameters, the average root-mean square strain, which describes the distribution of the inhomogeneous strain field, was calculated. Finally, the average residual stresses in cold-canailed stainless steel 304 plates were shown to be a combination effect of hydrostatic stresses of martensite particles and austenite matrix. The average residual stresses were evaluated from the experimentally determined average lattice strains in each phase. It was found the tensile residual stress in a cuplikan was maximum, reaching 442 MPa, for a cuplikan reducing 34% in thickness and minimum for a 196% cuplikan

Quantitative study of Portland cement hydration by X-ray diffraction/Rietveld analysis and independent methods

International Nuclear Information System (INIS)

Scrivener, K.L.; Fuellmann, T.; Gallucci, E.; Walenta, G.; Bermejo, E.

2004-01-01

X-ray diffraction (XRD) is a powerful technique for the study of crystalline materials. The technique of Rietveld refinement now enables the amounts of different phases in anhydrous cementitious materials to be determined to a good degree of precision. This paper describes the extension of this technique to a pilot study of the hydration of a typical Portland cement. To validate this XRD-Rietveld analysis technique, its results were compared with independent measures of the same materials by the analysis of backscattered electron images (BSE/IA) and thermogravimetric analysis (TGA). In addition, the internal consistency of the measurements was studied by comparing the XRD estimates of the amounts of hydrates formed with the amounts expected to form from the XRD estimates of the amounts of anhydrous materials reacted

Quantitative determination of the crystalline phases of the ceramic materials utilizing the Rietveld method

International Nuclear Information System (INIS)

Kniess, C.T.; Prates, P.B.; Lima, J.C. de; Kuhnen, N.C.; Riella, H.G.; Maliska, A.M.

2009-01-01

Ceramic materials have properties defined by their chemical and micro-structural composition. The quantification of the crystalline phases is a fundamental stage in the determination of the structure, properties and applications of a ceramic material. Within this context, this study aims is the quantitative determination of the crystalline phases of the ceramic materials developed with addition of mineral coal bottom ash, utilizing the X ray diffraction technique, through the method proposed by Rietveld. For the formulation of the ceramic mixtures a {3,3} simplex-lattice design was used, giving ten formulations of three components (two different types of clays and coal bottom ash). The crystalline phases identified in the ceramic materials after sintering at 1150 deg C during two hours are: quartz, tridimite, mullite and hematite. The proposed methodology utilizing the Rietveld method for the quantification relating to crystalline phases of the materials was shown to be adequate and efficient. (author)

A research of the mineralogy phases of clinker in a spanish cement using the method of Rietveld

International Nuclear Information System (INIS)

Castanon Ana M; Garcia Granda Santiago; Guerrero Ana M; Gomez Fernandez Fernando

2012-01-01

In order to introduce continuously a quality control method in a Spanish cement factory to improve the final product feature new research methodology is being developed. The Rietveld method [1] has been successfully used to analyze the composition of the main phases of clinker. Using this methodologies, research has been carried out to quantize appropriately the minor phase of free lime which is extremely important in the clinker quality. This method leads to satisfactory results on samples with contents in CaO from 3%. These results are possible combining X- ray diffraction and fluorescence techniques as well as the chemical analysis data. Clinker, the Rietveld method, free lime.

Profex: a graphical user interface for the Rietveld refinement program BGMN

OpenAIRE

Doebelin, Nicola; Kleeberg, Reinhard

2015-01-01

Profex is a graphical user interface for the Rietveld refinement program BGMN. Its interface focuses on preserving BGMN’s powerful and flexible scripting features by giving direct access to BGMN input files. Very efficient workflows for single or batch refinements are achieved by managing refinement control files and structure files, by providing dialogues and shortcuts for many operations, by performing operations in the background, and by providing import filters for CIF and XML crystal str...

The use of the Rietveld method as an evaluation tool in the stages of production of nanostructured hard metal

International Nuclear Information System (INIS)

Batista, A.C.; Perpetuo, G.J.; Oliveira, H.C.P. de; Silva, T.R.G. da

2014-01-01

The processing of the composite WC-10% Co, with nanometric grain size was analyzed aiming at identifying changes undergone by the material during mixing and compaction steps. Use the X-ray diffraction and the Rietveld method to obtain accurate data on the behavior of powders before these steps. This paper describes the use of the Rietveld method as an evaluation tool to obtain information about the behavior of powders of WC and Co steps during mixing and compaction prior to sintering of the composite. (author)

Combined PDF and Rietveld studies of ADORable zeolites and the disordered intermediate IPC-1P

Czech Academy of Sciences Publication Activity Database

Morris, S. A.; Wheatley, P. S.; Položij, M.; Nachtigall, P.; Eliášová, Pavla; Čejka, Jiří; Lucas, T. C.; Hriljac, J. A.; Pinar, A. B.; Morris, R. E.

2016-01-01

Roč. 45, č. 36 (2016), s. 14124-14130 ISSN 1477-9226 R&D Projects: GA ČR GBP106/12/G015 Institutional support: RVO:61388955 Keywords : Distribution functions * Rietveld refinement * Zeolites Subject RIV: CF - Physical ; Theoretical Chemistry Impact factor: 4.029, year: 2016

Micro-structural study and Rietveld analysis of fast reactor fuels: U-Mo fuels

Science.gov (United States)

Chakraborty, S.; Choudhuri, G.; Banerjee, J.; Agarwal, Renu; Khan, K. B.; Kumar, Arun

2015-12-01

U-Mo alloys are the candidate fuels for both research reactors and fast breeder reactors. In-reactor performance of the fuel depends on the microstructural stability and thermal properties of the fuel. To improve the fuel performance, alloying elements viz. Zr, Mo, Nb, Ti and fissium are added in the fuel. The first reactor fuels are normally prepared by injection casting. The objective of this work is to compare microstructure, phase-fields and hardness of as-cast four different U-Mo alloy (2, 5, 10 and 33 at.% Mo) fuels with the equilibrium microstructure of the alloys. Scanning electron microscope with energy dispersive spectrometer and optical microscope have been used to characterize the morphology of the as-cast and annealed alloys. The monoclinic α'' phase in as-cast U-10 at.% Mo alloy has been characterized through Rietveld analysis. A comparison of metallographic and Rietveld analysis of as-cast (dendritic microstructure) and annealed U-33 at.% Mo alloy, corresponding to intermetallic compound, has been reported here for the first time. This study will provide in depth understanding of microstructural and phase evolution of U-Mo alloys as fast reactor fuel.

Quantitative phase analysis of uranium carbide from x-ray diffraction data using the Rietveld method

International Nuclear Information System (INIS)

Singh Mudher, K.D.; Krishnan, K.

2003-01-01

Quantitative phase analysis of a uranium carbide sample was carried out from the x-ray diffraction data by Rietveld profile fitting method. The method does not require the addition of any reference material. The percentage of UC, UC 2 and UO 2 phases in the sample were determined. (author)

Aplicación de tratamiento electroquímico a baja intensidad de corriente para la extracción de cloruros en objetos arqueológicos de hierro de procedencia subacuática. Observación de la evolución de fases mineralógicas mediante XRD-Rietveld

Directory of Open Access Journals (Sweden)

Bethencourt, M.

2004-12-01

Full Text Available With the purpose of optimising a suitable methodology for the conservation of an archaeological object of iron, a low current intensities electrolytic treatment has been applied, to a piece of cast iron, proving to be effective in the extraction of chloride ions from the structure of akaganeite, principal corrosion product of iron in the marine medium. The monitoring of the electrolytic treatment has been proven by applying the "Rietveld" method to the patterns XRD of samples extracted from the corroded surface before and after the treatment. This method has permitted the unequivocal determination of the akaganeite and its chemical composition. This identification has been corroborated by means of SEM and EDS. After the electrolytic treatment, akaganeite was not present in the sample.

Con objeto de optimizar una metodología adecuada para la conservación de una pieza de hierro arqueológico de fundición, se ha aplicado un tratamiento electrolítico a bajas intensidades de corriente, demostrando su efectividad en la extracción de iones cloruro de la estructura de akaganeita, principal producto de corrosión del hierro en medio marino. La monitorización del proceso se ha comprobado aplicando el método Rietveld a los patrones XRD de muestras extraídas de la superficie corroída antes y después del tratamiento. Este método ha permitido la determinación inequívoca de la akaganeita y la composición química de este oxihidróxido de hierro no estequiométrico. Dicha identificación se corrobora mediante SEM y EDS. Después del tratamiento electrolítico la akaganeita no está presente en la muestra.

Crystal structure analysis of LaMnO_3 with x-ray diffraction technique using the Rietveld method

International Nuclear Information System (INIS)

Engkir Sukirman; Wisnu Ari Adi; Yustinus Purwamargapratala

2010-01-01

Crystal structure analysis of LaMnO_3 using the Rietveld method has been carried out. The LaMnO_3 sample was synthesized with high energy mechanical milling from the raw materials of La_2O_3 and MnO_2 with the appropriate mol ratio. Milling were performed for 10 hours, pelletized and hereinafter sintered at 1350 °C for 6 hours. The sample characterizations covered the crystal structure and electric-magnetic properties of the materials by X-ray diffraction technique using the Rietveld method and the four point probe, respectively. The Rietveld refinement results based on the X-rays diffraction data indicate that the sample of LaMnO_3 is single phase with the crystal system: orthorhombic, the space group: Pnma No. 62 and the lattice parameters: a = 55.4405(9) Å; b = 7.717(1) Å dan c = 5.537(1) Å. The material owns Magnetic Resonance (MR) respond of 7 %, the mean value of crystallite size, D = 17 nm and lattice strain, e = - 0.5 %. So, the material go through a compressive strain, and according to the Nanda's strain model, it becomes a type G antiferromagnetic insulator. Because the insulator properties of the material does not change although being hit by the external magnetic field, hence the MR respond is only caused by the order of electron spin. Therefore at room temperature, LaMnO_3_._0 just exhibits a small MR respond. (author)

Investigation on the evolution of microstructure and texture of electroplated Ni–Ti composite coating by Rietveld method

Energy Technology Data Exchange (ETDEWEB)

Zhao, Yuantao, E-mail: zhaoyuantao@sjtu.edu.cn; Cai, Fei, E-mail: caifei32@126.com; Wang, Chengxi, E-mail: sjtucxw@sjtu.edu.cn; Chai, Ze, E-mail: zechaisjtu@163.com; Zhu, Kaiyuan, E-mail: xrd125@163.com; Xu, Zhou, E-mail: xuzhou@sjtu.edu.cn; Jiang, Chuanhai, E-mail: chjiang-sjtu@hotmail.com

2015-10-30

Highlights: • Ni–Ti composite coatings were prepared by electroplating. • Morphology and Ti content of Ni–Ti coatings were studied upon SEM and EDXS. • Microstructures of Ni–Ti coatings were studied upon the Rietveld method. • The texture of Ni–Ti coatings was studied upon the pole figure. - Abstract: Rietveld refinement was utilized to investigate the evolution of microstructure and texture of the Ni–Ti composite coatings electroplated at different applied current densities. Scanning Electron Microscope and Energy Dispersive Spectroscopy were utilized to investigate the morphology and chemical composition of the coatings. Relative texture coefficients (RTC) and measured pole figures were utilized to investigate the texture evolution of the coatings. The results showed that the surface morphology of the coatings changed from a colonial structure to a polyhedral one. And the incorporated Ti content decreased with increasing applied current density. As the applied current density increased, the crystallite sizes increased and their distribution got less uniform, and the microstrain and dislocation density decreased. The results of simulated pole figures obtained from Rietveld refinement illustrated that the texture of the coatings changed from no obvious texture to a strong [2 0 0] fiber texture with increasing applied current density. The texture evolution obtained from simulated pole figures was confirmed by the result of RTC and the measured pole figures. The evolutions of the microstructure and texture were derived from the change of the applied current density and incorporated Ti content in the Ni–Ti composite coatings.

Rietveld refinement of the structures of 1.0 C-S-H and 1.5 C-S-H

KAUST Repository

Battocchio, Francesco; Monteiro, Paulo J.M.; Wenk, Hans-Rudolf

2012-01-01

Low-Q region Rietveld analyses were performed on C-S-H synchrotron XRD patterns, using the software MAUD. Two different crystal structures of tobermorite 11 Å were used as a starting model: monoclinic ordered Merlino tobermorite, and orthorhombic

Structural Rietveld refinement and vibrational study of MgCr{sub x}Fe{sub 2−x}O{sub 4} spinel ferrites

Energy Technology Data Exchange (ETDEWEB)

Sabri, K. [Laboratoire des Sciences et technique de l’Environnement et de la Valorisation, département de Génie des Procédés, Université de Mostaganem, Mostaganem (Algeria); Rais, A., E-mail: amrais@yahoo.com [Laboratoire des Sciences et technique de l’Environnement et de la Valorisation, département de Génie des Procédés, Université de Mostaganem, Mostaganem (Algeria); Taibi, K. [Laboratoire de Science et Génie des Matériaux, USTHB, Alger, Algéria (Algeria); Moreau, M.; Ouddane, B. [Laboratory of LASIR Spectrochemistry, University of Science and Technology, 59650 Villeneuve d’Ascq (France); Addou, A. [Laboratoire des Sciences et technique de l’Environnement et de la Valorisation, département de Génie des Procédés, Université de Mostaganem, Mostaganem (Algeria)

2016-11-15

Spinel ferrites with the general formula MgCr{sub x}Fe{sub 2−x}O{sub 4} (0≤x≤1) were synthesized by the standard ceramic technique and characterized by X-ray diffraction. The XRD patterns confirmed that the mixed ferrite samples are in the cubic spinel structure which is further validated by Rietveld refinement in the space group Fd3m. The crystal structure and cell parameters were refined by Rietveld analysis. The vibrational study was achieved using Fourier Transform-InfraRed (FT-IR) and Raman spectroscopy. From FT-IR band frequencies, the force constants K{sub t} and K{sub o} , for tetrahedral (A) and octahedral (B) sites respectively, have been calculated and discussed with the trend of bond lengths obtained from Rietveld refinement. For all compositions, Raman spectra revealed the five active modes showing the vibration of O{sup 2−} ions at both the A-site and B-site ions. The frequencies trend with chromium content of both FT-IR and Raman spectra showed a shift toward higher values for all modes.

Quantitative determination of phases in ZrO2 (MgO) (Y2O3) using the Rietveld method

International Nuclear Information System (INIS)

Castro, Antonio Carlos de

2007-01-01

The key objective of this work is the crystallographic characterization of the zircon co-doped with Yttria and magnesium with the application of the Rietveld method for quantitative phase analysis of zircon polymorph (zircon monoclinic, tetragonal, and cubic). Samples of zircon polymorph were obtained from zircon doped with Yttria and magnesium at defined molar concentrations. The zircon polymorph stability during subeutetoid aging at 1350 deg C were investigated to determine ZrO 2 - MgO - Y 2 0 3 phases degradation and to define the solid solutions stability environment. ZrO 2 powders doped with 8 mol por cent of MgO and 1 mol por cent of Y 2 O 3 , and 9 mol por cent of MgO and 0 mol por cent of Y 2 O 3 have been prepared by chemical route using the co-precipitation method. These samples have been calcinate at 550 deg C, sintered at 1500 deg C and characterized by the Rietveld method using the X-ray diffraction data. The variation of the lattice parameter, changes in the phase composition and their microstructures are discussed. The application of the Rietveld method for quantitative phase analysis of zircon polymorph (zircon tetragonal and cubic) reveals no formation of tetragonal phase and indicating that the matrix is the cubic phase with low concentration of monoclinic phase.(author)

Determination of phases of {alpha} - Fe{sub 2}O{sub 3}: SiO{sub 2} compound by the Rietveld refinement

Energy Technology Data Exchange (ETDEWEB)

Palomares S, S.A. [Istituto Materiali Speciali per Elettronica e Magnetismo (MASPEC), Parco Area delle Scienze 37A-43010 Loc. Fontanni, Parma (Italy); Ponce C, S.; Martinez, J.R. [Facultad de Ciencias, Universidad Autonoma de San Luis Potosi, 78000 San Luis Potosi (Mexico); Ruiz, F. [Instituto Potosino de Investigacion Cientifica y Tecnologica, Av. V. Carranza 2025, San Luis Potosi (Mexico)

2002-07-01

We use a variation of the Rietveld refinement method to calculate the amorphous content of composites formed by a silica xerogel amorphous matrix and iron particles embedded into. In order to apply the Rietveld refinement to amorphous structures an initial crystalline model is assumed with the same composition as the material to be modelled. In this work we try to refine the structure of compounds using the program MAUD. It is shown how this program can be used to determine the amorphous and crystalline fractions in composites consisting of an amorphous matrix and incorporated iron oxide particles. The analysed compounds underwent different thermal treatments. (Author)

Análisis de las poblaciones de microorganismos fijadores de nitrógeno del suelo aplicando procedimientos metagenómicos

OpenAIRE

Calderoli, Priscila Anabel

2016-01-01

En este trabajo de tesis doctoral se llevó a cabo el análisis de las poblaciones de microorganismos fijadores de nitrógeno del suelo aplicando análisis independientes del cultivo. Se analizaron suelos de la principal región agrícola de la Argentina, la región pampeana.

Rietveld refinement of magnetic structures from pulsed-neutron-source powder-diffraction data

International Nuclear Information System (INIS)

Robinson, R.A.; Lawson, A.C.; Larson, A.C.; Von Dreele, R.B.; Goldstone, J.A.

1994-01-01

The General Structure Analysis System, GSAS, has recently been modified to include magnetic neutron- scattering cross-sections. Low-temperature diffraction data have been taken on the hexagonal noncollinear antiferromagnet UPdSn on both the HIPD and the NPD powder diffractometers ail LANSCE. The low-resolution data reveal that the magnetic structure has orthorhombic symmetry (magnetic space group P c m'c2 1 ) between 25K and 40K, and monoclinic symmetry (magnetic space group PC 1121 ) below 25K. The high-resolution data reveal that there are structural distortions with corresponding symmetry changes in each of these phases, to give chemical space groups Cmc2 1 and P2 1 , respectively, while the paramagnetic phase above 40K has space group P6 3 mc. Using GSAS, we have refined data sets from both diffractometers simultaneously, including both magnetic and structural cross-sections. Magnetoelastic coefficients for the distortions have been extracted and we have determined the sign of the coupling between the structural monoclinicity and the magnetic monoclinicity. The magnetic results from Rietveld refinement are in good agreement with model fitting to the integrated intensities of seven independent magnetic reflections and these, in turn, agree with measurements made on the same sample using the constant-wavelength reactor technique. Our results therefore validate, to some level, both the technique of using spallation sources for complicated magnetic structures and the specifics of the GSAS Rietveld code

Study of crystallite size of yttria-stabilized zirconia powders by Rietveld method

International Nuclear Information System (INIS)

Leite, Wellington Claiton; Brinatti, Andre Mauricio; Ribeiro, Mauricio Aparecido; Andrade, Andre Vitor Chaves de; Chinelatto, Adriana Scoton Antonio; Chinelatto, Adilson Luiz

2009-01-01

The yttria-stabilized zirconia (YSZ) is used in a great variety of applications, for example, electrolytes of solid oxide fuel cells and oxygen sensors. In the study of YSZ, the particle size powders and sintering processes are important to define the final properties of the zirconia products. The objectives of this work were to determine the phases and the crystalline size using X-Ray Diffraction (XRD) data and the Rietveld Method (RM) of the YSZ powders obtained by chemical synthesis based on the Pechini method. It was used ZrOCl 2.8 H 2 O and Y(NO 3 ) 3.5 H 2 O as precursors reagents. After calcination at 550 deg C during 24 hours, the powder was analyzed by XRD and scanning electronic microscopy (SEM). From XRD and using Rietveld method were verified that there is only cubic phase with lattice parameter a = 5.1307(1) Å and the space group Fm3m. Due to substitution of the Zr atoms in the Y atoms sites, there were vacancies in 17.72 % of O atoms sites. However, the percentage of substitution of Zr atoms in Y atoms sites in the structure not was determinate because the curves of atomic scattering of them are very similar. Using Scherrer equation and considering anisotropy effect, the average crystalline size was determinate: 10,43 nm (c axis) and 10,39 (b axis). This spherical symmetry also observed for SEM. (author)

Análisis de las poblaciones de microorganismos fijadores de nitrógeno del suelo aplicando procedimientos metagenómicos

OpenAIRE

Calderoli, Priscila Anabel

2016-01-01

En este trabajo de tesis doctoral se llevó a cabo el análisis de las poblaciones de microorganismos fijadores de nitrógeno del suelo aplicando análisis independientes del cultivo. Se analizaron suelos de la principal región agrícola de la Argentina, la región pampeana. Facultad de Ciencias Exactas

Quantitative determination of phases in ZrO{sub 2} (MgO) (Y{sub 2}O{sub 3}) using the Rietveld method; Determinacao quantitativa de fases em ZrO{sub 2} - MgO - Y{sub 2}O{sub 3} utilizando o metodo de Rietveld

Energy Technology Data Exchange (ETDEWEB)

Castro, Antonio Carlos de

2007-07-01

The key objective of this work is the crystallographic characterization of the zircon co-doped with Yttria and magnesium with the application of the Rietveld method for quantitative phase analysis of zircon polymorph (zircon monoclinic, tetragonal, and cubic). Samples of zircon polymorph were obtained from zircon doped with Yttria and magnesium at defined molar concentrations. The zircon polymorph stability during subeutetoid aging at 1350 deg C were investigated to determine ZrO{sub 2} - MgO - Y{sub 2}0{sub 3} phases degradation and to define the solid solutions stability environment. ZrO{sub 2} powders doped with 8 mol por cent of MgO and 1 mol por cent of Y{sub 2}O{sub 3}, and 9 mol por cent of MgO and 0 mol por cent of Y{sub 2}O{sub 3} have been prepared by chemical route using the co-precipitation method. These samples have been calcinate at 550 deg C, sintered at 1500 deg C and characterized by the Rietveld method using the X-ray diffraction data. The variation of the lattice parameter, changes in the phase composition and their microstructures are discussed. The application of the Rietveld method for quantitative phase analysis of zircon polymorph (zircon tetragonal and cubic) reveals no formation of tetragonal phase and indicating that the matrix is the cubic phase with low concentration of monoclinic phase.(author)

Separation of the overlapping effects in spectra for WDXRF using the Rietveld method

International Nuclear Information System (INIS)

Salvador, Vera Lucia Ribeiro

2005-01-01

This work presents a new methodology for the overlapping spectra separation obtained by the technique of wavelength dispersion X-ray fluorescence (WDXRF). This methodology allows to improve the conventional analytic results and to facilitate the determination of chemical species of a same element without chemical separation, by means of the separation of coming spectra of electronic transitions of valence electrons or chemical effects in internal electrons. With the software 'GSAS-EXPGUI' and the method of Rietveld overcomes the problem of overlapping lines of the present species in the sample and it facilitates the determination of the same ones simultaneously, without the need of samples patterns and calibration curves, what means an expressive gain in relation to other techniques. The preparation of the surface of the sample for the collection of the spectrum represents a critical stage for the acting of the analysis whose effects can be minimized being used the refinement of Rietveld, that allows the determination of the relationships of the intensities of the lines put upon by means of mathematical models, what establishes the basic conditions for obtaining of more precise results in the quantitative analysis. In the case of the determination of chemical species it can separate, for example Cr (III), Cr (VI) and Fe (II), Fe(III) that present overlapping of almost 100%. (author)

Rietveld and impedance analysis of cold and hot rolled duplex and lean duplex steels for application in paper and pulp industry

Energy Technology Data Exchange (ETDEWEB)

Esteves, Luiza; Lins, Vanessa de Freitas Cunha, E-mail: luizaeq@yahoo.com.br [Universidade Federal de Minas Gerais (UFMG), Belo Horizonte, MG (Brazil). Departamento de Engenharia Quimica; Paiva, Paulo Renato Perdigao [Centro Federal de Educacao Tecnologica de Minas Gerais (CEFET), Belo Horizonte, MG (Brazil); Viana, Adolfo Kalergis do Nascimento [APERAM South America, Timoteo, MG (Brazil)

2017-01-15

In this study, X-Ray Diffraction (XRD) and Rietveld Refinement were performed to identify and quantify the ferrite and austenite phase of cold and hot rolled duplex stainless steels (UNS S31803) and lean duplex stainless steels (UNS S32304). Electrochemical impedance spectroscopy (EIS) was applied to evaluate the chemical behavior of duplex and lean duplex stainless steels in white, green, and black liquors of paper and pulp industry. Rietveld analysis results showed a higher austenite content than the standard limit for duplex steels in the hot rolled condition. The hot rolling condition plays a major role in improving corrosion resistance in white liquor mainly for the lean duplex steel. (author)

Rietveld and impedance analysis of cold and hot rolled duplex and lean duplex steels for application in paper and pulp industry

International Nuclear Information System (INIS)

Esteves, Luiza; Lins, Vanessa de Freitas Cunha; Viana, Adolfo Kalergis do Nascimento

2017-01-01

In this study, X-Ray Diffraction (XRD) and Rietveld Refinement were performed to identify and quantify the ferrite and austenite phase of cold and hot rolled duplex stainless steels (UNS S31803) and lean duplex stainless steels (UNS S32304). Electrochemical impedance spectroscopy (EIS) was applied to evaluate the chemical behavior of duplex and lean duplex stainless steels in white, green, and black liquors of paper and pulp industry. Rietveld analysis results showed a higher austenite content than the standard limit for duplex steels in the hot rolled condition. The hot rolling condition plays a major role in improving corrosion resistance in white liquor mainly for the lean duplex steel. (author)

PLANEACIÓN DE UN SISTEMA SILVOPASTORIL EN LADERA EN HUATUSCO, VERACRUZ APLICANDO EL MÉTODO NEZAHUALCÓYOTL

Directory of Open Access Journals (Sweden)

L. Quinto

2009-01-01

Full Text Available El estudio describe el diseño e implementación de un módulo silvopastoril en ladera aplicando el método Nezahualcóyotl para establecer el componente arbóreo compuesto por: Swietenia macrophylla King (caoba, Tabebuia rosea (Bertol DC. (roble y Cedrela odorata L. (cedro rojo. El terreno se ubicó en la zona de Huatusco; en él se construyeron a nivel cinco bordos-zanjas, sobre los bordos se plantaron cada 4 m e intercalados, los árboles con dos meses de crecimiento en vivero. A cuatro meses de la plantación la supervivencia fue similar (a=0.05 entre especies y superior a 80 %. El componente ganadero no se implementó en campo sólo se describió su diseño y planeación, este componente consistió de pradera de Brachiaria brizantha y bovinos a media ceba. Se describe el establecimiento de la pradera mediante cultivo de maíz en aparcería. Se identifican los principales rubros de egresos para el establecimiento del módulo silvopastoril aplicando el método Nezahualcóyotl estimando como costo $ 44,347.00 por cada tercio de hectárea. Se concluyó que el método Nezahualcóyotl es una opción para el establecimiento del componente arbóreo de un sistema silvopastoril en terrenos con pendiente.

Ahorro de consumo de agua, aplicando técnicas de riego en jardines de la UNAC

OpenAIRE

Sánchez Hernández, Jaime Eloy

2013-01-01

La implementación del Proyecto "AHORRO DE CONSUMO DE AGUA, APLICANDO TECNICAS DE RIEGO EN JARDINES DE LA UNAC, con un sistema tecnificado de riego, específicamente por aspersión, se lograría ahorrar agua aproximadamente en un 50%. Además de personal de jardinería provista de mangueras (sistema de inundación) se dedicarían a otras labores que mejoren los jardines de la UNAC. Como corolario se tiene que no solo se ahorraría agua (pago de consumo a la empresa SEDAPAL), sino que al personal se...

Gerrit Rietveld. Casas después de la Schroeder

Directory of Open Access Journals (Sweden)

Rafael García

1997-07-01

Full Text Available Las historias de la arquitectura moderna han incidido una y otra vez en un reducido número de obras que por su insistente atención, han llegado a convertirse en hitos imprescindibles. Entre estos edificios canónicos y prácticamente obligados, está la célebre casa Schröder-Schräder (1924' del arquitecto holandés Gerrit Rietveld. Ampliamente conocida por el público interesado, su gran popularidad ha tenido sin embargo, el efecto de dejar en segundo plano el resto de su obra arquitectónica. A ello se debe añadir además, el hecho de que su trayectoria está fundamentalmente asociada al movimiento neoplasticista, lo que ha tenido por resultado desviar la atención de una obra posterior, más difícilmente clasificable. Sin embargo, ello no significa que dicha obra sea en absoluto carente de atractivo.

Evaluación de los efectos clínicos del blanqueamiento dental aplicando dos técnicas diferentes

OpenAIRE

Lahoud Salem, Victor; Mendoza Zapata, Janet; Uriarte Mora, Carlos; Munive Degregori, Arnaldo

2014-01-01

El objetivo del estudio fue evaluar los efectos clínicos del blanqueamiento dental aplicando dos técnicas diferentes. Técnica aplicada en consultorio. Técnica aplicada en Hogar. Fueron seleccionados 10 pacientes divididos en 2 grupos de 5 pacientes para cada técnica. Los criterios de evaluación fueron: duración de color, sensibilidad post operatoria, estado de salud gingival. Los resultados de la evaluación clínica a los 08 meses presentan 100% de estabilidad del color en los casos tratados c...

Magnesium substitution in carbonated hydroxyapatite: Structural and microstructural characterization by Rietveld's refinement

Energy Technology Data Exchange (ETDEWEB)

Lala, S. [Materials Science Division, Department of Physics, The University of Burdwan, Golapbag, Burdwan 713104, West Bengal (India); Ghosh, M.; Das, P.K. [Department of Biological Chemistry, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700 032 (India); Das, D. [UGC-DAE Consortium for Scientific Research, Kolkata 700098 (India); Kar, T. [Department of Materials Science, Indian Association for the Cultivation of Science, Jadavpur, Kolkata 700032 (India); Pradhan, S.K., E-mail: skpradhan@phys.buruniv.ac.in [Materials Science Division, Department of Physics, The University of Burdwan, Golapbag, Burdwan 713104, West Bengal (India)

2016-02-15

Four stoichiometric compositions of nanocrystalline Mg doped carbonated hydroxyapatite (cHAp) powders are synthesized by mechanical alloying (ball milling) the powder mixtures of CaCO{sub 3}, CaHPO{sub 4}.2H{sub 2}O and MgO in open air at room temperature. FTIR analysis confirms the A-type carbonation in all milled HAp powder samples (A-cHAp). Microstructure characterization in terms of lattice imperfections and phase quantification of ball milled samples are made by analyzing XRD patterns employing Rietveld's structure refinement method. Transmission electron microscopy (TEM) study of 15 mol % Mg doped A-cHAp sample reveals microstructure similar to that obtained from XRD pattern analysis. Cumulative effect of Mg substitution and mechanical alloying results in amorphization of a major part of crystalline A-cHAp, analogous to native bone mineral. Rietveld analysis reveals that the Ca2 vacancy site is energetically more favorable for occupation of Mg substitution. MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide] assay test reveals sufficiently high percentage cell viability confirming the cytocompatibility of the sample. - Graphical abstract: Mg substitution for Ca2 site. - Highlights: • Single phase Mg doped A-cHAp synthesized by mechanical alloying (MA). • FTIR analysis confirms A-type carbonation in HAp. • Amorphization of a part of crystalline A-cHAp due to MA and Mg insertion. • Mg{sup 2+} ions substitute the Ca2 vacancy site. • High cell viability under MTT assay.

The role of iron in tetrahedrite and tennantite determined by Rietveld refinement of neutron powder diffraction data

DEFF Research Database (Denmark)

Andreasen, Jens Wenzel; Makovicky, Emil; Lebech, Bente

2008-01-01

Rietveld refinement of neutron powder diffraction data on four samples of synthetic, iron-bearing tetrahedrite (Cu12-xFexSb4S13) with x = 0.28, 0.69, 0.91, 2.19 and four samples of synthetic tennantite (Cu12-xFexAs4S13) with x = 0.33, 0.38, 0.86, 1.5 indicate unambiguously that iron is incorporated...

Structural studies of TiC1−xOx solid solution by Rietveld refinement and first-principles calculations

International Nuclear Information System (INIS)

Jiang, Bo; Hou, Na; Huang, Shanyan; Zhou, Gege; Hou, Jungang; Cao, Zhanmin; Zhu, Hongmin

2013-01-01

The lattice parameters, structural stability and electronic structure of titanium oxycarbides (TiC 1−x O x , 0≤x≤1) solid solution were investigated by Rietveld refinement and first-principles calculations. Series of TiC 1−x O x were precisely synthesized by sintering process under the vacuum. Rietveld refinement results of XRD patterns show the properties of continuous solid solution in TiC 1−x O x over the whole composition range. The lattice parameters vary from 0.4324 nm to 0.4194 nm decreasing with increasing oxygen concentration. Results of first-principles calculations reveal that the disorder C/O structure is stable than the order C/O structure. Further investigations of the vacancy in Ti 1−Va (C 1−x O x ) 1−Va solid solution present that the structure of vacancy segregated in TiO-part is more stable than the disorder C/O structure, which can be ascribed to the Ti–Ti bond across O-vacancy and the charge redistributed around Ti-vacancy via the analysis of the electron density difference plots and PDOS. - Graphical abstract: XRD of series of titanium oxycarbides (TiC 1−x O x , 0≤x≤1) solid solution prepared by adjusting the proportion of TiO in the starting material. Highlights: • Titanium oxycarbides were obtained by sintering TiO and TiC under carefully controlled conditions. • Rietveld refinement results show continuous solid solution with FCC structure in TiC 1−x O x . • The disorder C/O structure is stable than the order C/O structure. • Introduction of vacancy segregated in TiO-part is more stable than disorder C/O structure. • Ti–Ti bond across O-vacancy and the charge redistributed around Ti-vacancy enhance structural stability

Detección automática de grietas de pavimento asfáltico aplicando características geométricas y descriptores de forma

Directory of Open Access Journals (Sweden)

Hernán Porras

2012-01-01

Full Text Available Las grietas son el principal daño en la superficie del pavimento, porque de estas se derivan los demás tipos de deterioros. La mayoría de grietas en imágenes de pavimento se encuentran con objetos no deseados y desconectadas. Para resolver este problema, se aplica el filtro mediana, para el suavizado de la imagen; el ajuste de contraste, para realzar la grieta; la segmentación, aplicando la media y la desviación estándar de los niveles de gris, para delimitar las grietas; el procesamiento morfológico, para fusionar separaciones estrechas; la eliminación de grietas falsas, aplicando características geométricas y descriptores de forma; y la conexión de grietas, para obtener grietas continuas. Los resultados experimentales fueron obtenidos de las imágenes de pavimento captadas por el sistema semiautomático y el algoritmo generador implementado. Las pruebas demostraron que las grietas fueron detectadas, con una sensibilidad de 81,72% y una especificidad de 99,96% para las imágenes captadas.

Effect of powder sample granularity on fluorescent intensity and on thermal parameters in x-ray diffraction Rietveld analysis

International Nuclear Information System (INIS)

Sparks, C.J.; Specht, E.D.; Ice, G.E.; Kumar, R.; Zschack, P.; Shiraishi, T.; Hisatsune, K.

1991-01-01

The effect of sample granularity on diffracted x-ray intensity was evaluated by measuring the 2θ dependence of x-ray fluorescence from various samples. Measurements were made in the symmetric geometry on samples ranging from single crystals to highly absorbing coarse powders. A characteristic shape for the absorption correction was observed. A demonstration of the sensitivity of Rietveld refined site occupation parameters is made on CuAu and Cu 50 Au 44 Ni 6 alloys refined with and without granularity corrections. These alloys provide a good example of the effect of granularity due to their large linear x-ray absorption coefficients. Sample granularity and refined thermal parameters obtained from the Rietveld analysis were found to be correlated. Without a granularity correction, the refined thermal parameters are too low and can actually become negative in an attempt to compensate for granularity. A general shape for granularity correction can be included in refinement procedures. If no granularity correction is included, data should be restricted to above 30 degrees 2θ, and thermal parameters should be ignored unless extreme precautions are taken to produce >5 μm particles and high packing densities

Synthesis and structural characterisation using Rietveld and pair distribution function analysis of layered mixed titanium-zirconium phosphates

International Nuclear Information System (INIS)

Burnell, Victoria A.; Readman, Jennifer E.; Tang, Chiu C.; Parker, Julia E.; Thompson, Stephen P.; Hriljac, Joseph A.

2010-01-01

Crystalline metal (IV) phosphates with variable zirconium-to-titanium molar ratios of general formula (Ti 1-x Zr x )(HPO 4 ) 2 .H 2 O have been prepared by precipitation of soluble salts of the metals with phosphoric acid and heating the amorphous solids in 12 M H 3 PO 4 in an autoclave. The new materials are structurally characterised by Rietveld analysis of synchrotron X-ray powder diffraction data and pair distribution function (PDF) analysis of high energy synchrotron X-ray total scattering data. A broad range of zirconium-titanium phosphate solid solutions were formed showing isomorphous substitution of titanium by zirconium in the α-titanium phosphate lattice and vice versa for titanium substitution into the α-zirconium phosphate lattice. In both cases the solubility is partial with the coexistence of two substituted phases observed in samples with nominal compositions between the solubility limits. - Graphical abstract: Layered phosphates of general formula (Ti 1-x Zr x )(HPO 4 ).H 2 O have been prepared by the hydrothermal treatment of amorphous gels in phosphoric acid and characterised by Rietveld analysis of high resolution synchrotron X-ray powder diffraction data and pair distribution function analysis of high energy synchrotron X-ray total scattering data.

Rietveld analysis and electronic bands structure on Tc superconductors systems

International Nuclear Information System (INIS)

Aldea, N.; Tiusan, C. V.; Sandu, V.

1999-01-01

A procedure for simultaneous refinement of structural and micro-structural disorder parameters for polycrystalline YBa 2 Cu 3 O 7-x system is proposed. It is based on Rietveld method combined with Fourier analysis for broadened peaks Another purpose of this paper consists in electronic structure determination studied by using the self-consistent Tight Binding Linear Muffin-Tin Orbital Atomic Spheres Approximation TB-LMTO-ASA methods. The Rietveld method uses an analytical function that describes the profiles, usually pseudo-Voigt (pV) or Pearson VII (PVII). The parameters of the analytical profiles describe its amplitude, position and peak shape. The full width at half maximum (FWHM) is supposed to vary with the diffraction angle in agreement with the Caglioti, Paoletti and Ricci's relationship. The best structural parameters are determined in the least squares sense by the minimisation a classical residual using the Marquardt method. In this case, the peak profiles were modelled by the pseudo-Voigt function corrected by the instrumental asymmetry. The physical information obtained are: scale factor, lattice parameters, atomic position and displacements, atomic occupation numbers, temperature factor (isotropy or anisotropy), preferred orientation parameter, crystalline size and micro-strain along different crystallographic directions, distributions of crystallite size and micro-strain functions. This procedure was implemented on computer code and it has a friendly graphical interface based on pull down menus technique. From the experimental point of view the X-ray diffraction data were collected using a horizontal powder diffractometer in the Bragg-Brentano (BB) geometry with a Ni filtered CuKα, λ = 1.54178 A, at room temperature using a DRON 2 set-up. The diffraction profiles were measured with a proportional gas detector, a single channel pulse-height discrimination and a standard associated counting circuit. The electronic band calculations are based on the TB

A Study on the quantification of hydration and the strength development mechanism of cementitious materials including amorphous phases by using XRD/Rietveld method

International Nuclear Information System (INIS)

Yamada, Kazuo; Hoshino, Seiichi; Hirao, Hiroshi; Yamashita, Hiroki

2008-01-01

X-ray diffraction (XRD)/Rietveld method was applied to measure the phase composition of cement. The quantative analysis concerning the progress of hydration was accomplished in an error of about the maximum 2-3% in spite of including amorphous materials such as blast furnace slag, fly ash, silica fume and C-S-H. The influence of the compressive strength on the lime stone fine powder mixture material was studied from the hydration analysis by Rietveld method. The two stages were observed in the strength development mechanism of cement; the hydration promotion of C 3 S in the early stage and the filling of cavities by carbonate hydrate for the longer term. It is useful to use various mixture materials for the formation of the resource recycling society and the durability improvement of concrete. (author)

Profex: a graphical user interface for the Rietveld refinement program BGMN.

Science.gov (United States)

Doebelin, Nicola; Kleeberg, Reinhard

2015-10-01

Profex is a graphical user interface for the Rietveld refinement program BGMN . Its interface focuses on preserving BGMN 's powerful and flexible scripting features by giving direct access to BGMN input files. Very efficient workflows for single or batch refinements are achieved by managing refinement control files and structure files, by providing dialogues and shortcuts for many operations, by performing operations in the background, and by providing import filters for CIF and XML crystal structure files. Refinement results can be easily exported for further processing. State-of-the-art graphical export of diffraction patterns to pixel and vector graphics formats allows the creation of publication-quality graphs with minimum effort. Profex reads and converts a variety of proprietary raw data formats and is thus largely instrument independent. Profex and BGMN are available under an open-source license for Windows, Linux and OS X operating systems.

Reducción de costo total de inventario aplicando un modelo de control de inventario del tipo (s,S).

OpenAIRE

Matos Quispe, Cesar Anibal; Matos Quispe, Cesar Anibal; Matos Quispe, Cesar Anibal

2012-01-01

El presente informe de suficiencia propone un modelo de control de inventario para minimizar los costos totales de inventario, aplicando una política de inventario de tipo (s, S) que es un modelo de control de inventario de clase estocástica. Explica cómo se desarrolla el modelo mediante el uso de la simulación Monte Cario tanto para simular el modelo de inventario, así como también la metodología de optimización para obtener los valores de decisión. Para el modelo de simulación se conside...

Refinement of the crystal structure of lead titanate with different degrees of imperfection of cationic and anionic sublattices by the Rietveld method

International Nuclear Information System (INIS)

Akimov, A.I.; Savchuk, G.K.; Rubtsov, V.A.; Letko, A.K.

2003-01-01

The parameters of the crystal structure of lead titanate with different degrees of imperfection of the anionic and cationic sublattices are refined by the Rietveld method. The experiments are carried out on a DRON-4 diffractometer (CuK α radiation; 20 deg. d 5.0-6.0%

Effect of data quality on quantitative phase analysis (QPA) using the Rietveld method

International Nuclear Information System (INIS)

Scarlett, N.; Madsen, I.; Lwin, T.

1999-01-01

Full text: Quantitative phase analysis using the Rietveld method has become a valuable tool in modern X-ray diffraction. XRD is a recognised research tool and has been successfully employed in the developmental stages of many industrial processes. It is now becoming increasingly important as a means of process control either (i) in site quality control laboratories or (ii) even on-line. In on-line applications, the optimisation of data collection regimes is of critical importance if rapid turn-around, and hence timely process control, is to be achieved. This paper examines the effect of data quality on the quantification of phases in well characterised suites of minerals. A range of data collection regimes has been systematically investigated with a view to determining the minimum data required for acceptable quantitative phase analyses. Data has been collected with variations in the following process factors: 1st step, width ranging from 0.01 to 0.3 deg 2θ ;2nd step, counting time ranging from 0.0125 to 4 sec/step 3rd step, upper limit in the scan range varying from 40 to 148 deg 2θ. The data has been analysed using whole-pattern (Rietveld) based methods using two distinctly different analytical approaches: (i) refinement of only pattern background and individual scale factors for each phase; (ii) refinement of unit cell dimensions, overall thermal parameters, peak width and shape in addition to the background and scale factors. The experimental design for this work included a ternary design of the three component phases (fluorite, CaF 2 ; zincite, ZnO; corundum, Al 2 O 3 ) to form seven mixtures of major and minor phases of different scattering powers and the combination of the three process factors (variables) to form a factorial plan. The final data generation plan is a combination/crossing of the three process variable factorial plan with the three component mixture plan. It allows a detailed data analysis to provide information on the effect of the process

Rietveld refinement and FTIR analysis of bulk ceramic Co3-xMnxO4 compositions

Science.gov (United States)

Meena, P. L.; Kumar, Ravi; Sreenivas, K.

2013-02-01

Co3-xMnxO4 (x = 0.0, 0.6, 1.2) prepared by solid state reaction method and characterized by powder X-ray diffraction (XRD) and Fourier transform infrared (FTIR). Lattice parameters (a), oxygen parameter (u), and ionic radii of cations have been determined through Rietveld analysis. Both a and u parameters are related to expansion of octahedral site as Mn content in Co3O4. Analysis of XRD data show that Mn (x ≤ 1.2) is accommodated at the octahedral site, while retaining the cubic spinel structure. FTIR results also confirm the same and signify strong interactions due to overlapping of Co and Mn octahedra.

Crystal structures of iron bearing tetrahedrite and tennantite at 25 and 250 degrees C by means of Rietveld refinement of synchrotron data

DEFF Research Database (Denmark)

Friese, K.; Grzechnik, A.; Makovicky, E.

2008-01-01

Rietveld refinement of X-ray synchrotron data was performed for two synthetic tetrahedrite samples, with 0.61 and 1.83 Fe atoms, and two synthetic tennantite samples with 0.10 and 1.23 Fe atoms p.f.u. M-12(Sb,As)(4)S-13. Measurements were performed at 25 and 250 degrees C. For both the phases...

PETROGRAPHY AND APPLICATION OF THE RIETVELD METHOD TO THE QUANTITATIVE ANALYSIS OF PHASES OF NATURAL CLINKER GENERATED BY COAL SPONTANEOUS COMBUSTION

Directory of Open Access Journals (Sweden)

Pinilla A. Jesús Andelfo

2010-06-01

Full Text Available

Fine-grained and mainly reddish color, compact and slightly breccious and vesicular pyrometamorphic rocks (natural clinker are associated to the spontaneous combustion of coal seams of the Cerrejón Formation exploited by Carbones del Cerrejón Limited in La Guajira Peninsula (Caribbean Region of Colombia. These rocks constitute remaining inorganic materials derived from claystones, mudstones and sandstones originally associated with the coal and are essentially a complex mixture of various amorphous and crystalline inorganic constituents. In this paper, a petrographic characterization of natural clinker, aswell as the application of the X-ray diffraction (Rietveld method by mean of quantitative analysis of its mineral phases were carried out. The RIQAS program was used for the refinement of X ray powder diffraction profiles, analyzing the importance of using the correct isostructural models for each of the existing phases, which were obtained from the Inorganic Crystal Structure Database (ICSD. The results obtained in this investigation show that the Rietveld method can be used as a powerful tool in the quantitative analysis of phases in polycrystalline samples, which has been a traditional problem in geology.

Study of the superconducting compound Hg,Re-1223 by X-Ray diffraction with application of Rietveld method

International Nuclear Information System (INIS)

Putvinskis, Rodrigo

2008-01-01

The objective of this work was to study the crystal structure of the superconductor compound of nominal composition Hg 0,82 Re 0,18 Ba 2 Ca 2 Cu 3 O 8+δ and general formula Hg,Re- 1223 and different oxygen contents, by the X-ray diffraction technique, by using the Rietveld method. The studied samples present different oxygen stoichiometry because during the synthesis process, had been heat treated under different oxygen/argon gas mixtures in the ratios: 5:95, 10:90 and 15:85. The results of structural refinement for the samples show that different oxygen contents imply in different cell parameters, atomic positions and distances for the main phase of each sample. The segregation of two superconducting phases with the same crystal structure, but slightly different cell parameters was confirmed for the studied samples both by Rietveld analysis and anomalous X-ray diffraction experiments. It was also confirmed that one of the segregated phases does not incorporate Re cations its composition. The main phase, who incorporates the Re cations, is here called Hg,Re-1223 and the Re-free secondary phase is called Hg- 1223. It was found that the superconducting phases present different crystallite sizes and the sample treated under gas flow composed of 10% oxygen and 90% argon presents the highest fraction of superconducting phases. From these results it was possible to conclude that the sample produced from the precursor compound treated under flow of O 2 /Ar gas at the ratio 10/90 presents the better results for the synthesis of this superconducting compound. (author)

A research of the mineralogy phases of clinker in a spanish cement using the method of Rietveld

International Nuclear Information System (INIS)

Castanon, Ana M; Garcia, Granda Santiago; Guerrero, Ana M; Gomez Fernandez, Fernando

2012-01-01

In order to introduce continuously a quality control method in a Spanish cement factory to improve the final product feature new research methodology is being developed. The Rietveld method [1] has been successfully used to analyze the composition of the main phases of clinker. Using this methodologies, research has been carried out to quantize appropriately the minor phase of free lime which is extremely important in the clinker quality. This method leads to satisfactory results on samples with contents in CaO from 3%. These results are possible combining X- ray diffraction and fluorescence techniques as well as the chemical analysis data.

Neutron irradiated uranium silicides studied by neutron diffraction and Rietveld analysis

International Nuclear Information System (INIS)

Birtcher, R.C.; Mueller, M.H.; Richardson, J.W. Jr.; Faber, J. Jr.

1989-11-01

Uranium silicides have been considered for use as reactor fuels in both high power and low enrichment applications. However, U 3 Si was found to become amorphous under irradiation and to become mechanically unstable to rapid growth by plastic flow. U 2 Si 2 appears to be stable against amorphization at low displacement rates, but the extent of this stability is uncertain. Although the mechanisms responsible for plastic flow in U 3 Si and other amorphous systems are unknown, as is the importance of crystal structure for amorphization, it may not be surprising that these materials amorphize, in light of the fact that many radioactive nuclide - containing minerals are known to metaminctize (lose crystallinity) under irradiation. The present experiment follows the detailed changes in the crystal structures of U 3 Si and U 3 Si 2 introduced by neutron bombardment and subsequent uranium fission at room temperature. U-Si seems the ideal system for a neutron diffraction investigation since the crystallographic and amorphous forms can be studied simultaneously by combining conventional Rietveld refinement of the crystallographic phases with Fourier-filtering of the non-crystalline scattering component

Rietveld refinement of Y2O3 using the pearson VII profile shape function

International Nuclear Information System (INIS)

Smrcok, L.

1989-01-01

Very good agreement between the observed and the calculated intensities was obtained using the Pearson VII profile shape function. The variable exponent m could be refined only in the damped iterations involving exclusively the profile parameters. Simultaneous refinement of the m with the positional and/or thermal parameters has led to large oscillations of the shifts of almost all parameters. Precision of the refined atomic coordinates is better than those from previously published Rietveld refinement and is comparable with single crystal results. The degree of serial correlation in residuals has been determined by the use of the Durbin-Watson d statistic. Normal probability plot based on δR i has been almost linear with the slope greater than one. The weighting scheme with w i = 1/y oi has proved to be good first approximation. (author)

Crystal phase analysis of SnO2-based varistor ceramic using the Rietveld method

International Nuclear Information System (INIS)

Moreira, M.L.; Pianaro, S.A.; Andrade, A.V.C.; Zara, A.J.

2006-01-01

A second addition of l mol% of CoO to a pre calcined SnO 2 -based ceramic doped with 1.0 mol% of CoO, 0.05 mol% of Nb 2 O 5 and 0.05 mol% of Cr 2 O 3 promotes the appearance of a secondary phase, Co 2 SnO 4 , besides the SnO 2 cassiterite phase, when the ceramic was sintered at 1350 deg. C/2 h. This was observed using X-ray powder diffraction, scanning electron microscopy and energy dispersive X-ray techniques. Rietveld refinement was carried out to quantify the phases present in the ceramic system. The results of the quantitative analysis were 97 wt.% SnO 2 and 3 wt.% Co 2 SnO 4 . The microstructural analysis showed that a certain amount of cobalt ion remains into cassiterite grains

Refinement by Rietveld method of a rolled sheet Al-Mg-Si 6063 alloy with preferential orientation

International Nuclear Information System (INIS)

Carrio, J.A.G.; Hattori, C.S.; Miranda, L.F.; Domingues Junior, N.I.; Lima, N.B.; Couto, A.A.; Aguiar, A.A.

2010-01-01

The Rietveld refinement of a sample with preferential orientation was accomplished using data of X ray diffraction of a rolled 6063 aluminum alloy. The refinement of the preferential orientation by spherical harmonic was accomplished using a symmetry of sample mmm (rolling) until the order of 8 and was compared with experimental pole figures. The four pole figures presented indicate a sharp texture of the planes (111), (200), (220) and (311). The calculated pole figures obtained from the refinement of the X ray diffraction spectrum can incur in mistakes of preferential orientation. This happens because the measure is restricted to the planes parallel to the surface without inference to the symmetry of the sample. (author)

Rietveld quantitative phase analysis of high surface area commercial alumina doped with niobia

International Nuclear Information System (INIS)

Gomes, L.B.; Pereira, A.S.; Pokorny, A.; Bergmann, C.P.

2014-01-01

The quantification of crystalline phases present in a given material can provide important information about the phenomena related to the diffusion of new elements in a ceramic matrix, as well as the formation and precipitation of minority phases and their microstructural evaluation. In this work, a high content of niobia (16 and 32 %w.t)was added to a high specific surface commercial alumina powder. The specimens were uniaxially pressed (200 MPa) and sintered in two stages: a first step at 1100°C for 3, 6 or 9 hours followed by a second step at 1350°C for 3 hours. The crystalline phases were analyzed by X-ray Diffraction (XRD) and quantified by the Rietveld method. The morphology of the samples was evaluated by Scanning Electron Microscopy (SEM). From the results obtained, some aluminum niobates phases expected for the Al_2O_3-Nb_2O_5 system could be identified as an intergranular phase and their relative fraction was quantified. (author)

Dirección del proyecto para la construcción del casco habitable del edificio multifamiliar Pramin, aplicando estándares del PMI

OpenAIRE

Cabrejos Canevaro, Omar; Garrido Lovón, Johan; Herrera Stoll, Alberto; Ramírez Apón, Ernesto

2017-01-01

La presente tesis tiene como objetivo principal el desarrollo de la Dirección de un proyecto para la construcción del Casco Habitable del Edificio Multifamiliar Pramin, ejecutado por la empresa Construcciones Corbus S.A., aplicando los estándares de la Guía del PMBOK, quinta edición, se busca lograr una ventaja competitiva sostenible en el tiempo a través de un modelo de dirección eficiente en sus procesos que sirva como base actualizable para la ejecución de cada proyecto de la empresa a fin...

EVALUACIÓN DEL DESEMPEÑO HIDRAULICO DE TRES GOTEROS APLICANDO AGUA RESIDUAL DE PORCICULTURA

Directory of Open Access Journals (Sweden)

RAFAEL OLIVEIRA BATISTA

2012-01-01

Full Text Available La realización de este trabajo tuvo por objetivo, analizar el desempeño hidráulico de tres goteros aplicando agua residual de porcicultura tratada. Fue montada una estructura hidráulica de evaluación constituida de tres tipos de goteros (G1, G2 y G3. Se mantuvo la presión del servicio en el inicio de las líneas laterales en 105 kPa y se cuantificaron en intervalo de 20 h, el caudal de los goteros hasta la obtención de un tiempo total de 160 h de operación del sistema. El nivel de taponamiento de los goteros fue obtenido por medio del coeficiente de variación del caudal (CVQ. Con la aplicación de agua residual de porcicultura, hubo un aumento del CVQ a lo largo del tiempo de funcionamiento, solamente en la sub-unidad con gotero G2. Los goteros de mayor caudal e menor largura de laberinto son menos susceptibles al taponamiento. La formación de biofilme fue resultado de la interacción entre sólidos suspendidos, azufre y bacterias, consistiendo en el principal factor de taponamiento parcial y total de los goteros.

Mineralogical analysis of clays in hardsetting soil horizons, by X-ray fluorescence and X-ray diffraction using Rietveld method

International Nuclear Information System (INIS)

Prandel, L.V.; Saab, S.C.; Brinatti, A.M.; Giarola, N.F.B.; Leite, W.C.; Cassaro, F.A.M.

2014-01-01

Diffraction and spectroscopic techniques have been shown to be suitable for obtaining physical and mineralogical properties in polycrystalline soil samples, and also in their precursor compounds. For instance, the X-ray fluorescence (XRF) spectroscopy allows obtaining the elemental composition of an investigated sample, while the X-ray diffraction (XRD) technique permits obtaining qualitative and quantitative composition of the soil minerals through the Rietveld method (RM). In this study Yellow Latosol (Oxisol), Yellow Argisol (Ultisol) and Gray Argisol (Ultisol) soil samples, classified as “hardsetting soils”, extracted from areas located at Northeast and Southeast of Brazilian coast were investigated. The soils and their fractions were analyzed in an EDX-700 and an XRD-6000 (Cu K α radiation). XRF results indicate high percentages of Si and Al, and small percentage of Fe and Ti in the investigated samples. The DRX data and RM indicate that there was a predominance of kaolinite and halloysite minerals (kaolin group minerals) in the clay fractions, which are presumably responsible for the formation of kaolinitic plasma in these soils. Also, the obtained results showed that the XRF, XRD techniques and RM were very helpful for investigating the mineralogical composition of a hardsetting soil. - Highlights: ► Elemental composition of soil samples through X-Ray fluorescence. ► Mineralogical quantification through X-ray diffraction and Rietveld method. ► Oxisol and Ultisol, Brazil ‘Barreiras’ formation. ► High amounts of Si and Al oxides and low amounts of Fe and Ti oxides. ► Predominance of kaolinite in the clay fraction

Assessment of firing conditions in old fired-clay bricks. The contribution of X-ray powder diffraction with the Rietveld method and small angle neutron scattering

Czech Academy of Sciences Publication Activity Database

Viani, Alberto; Sotiriadis, Konstantinos; Len, A.; Šašek, Petr; Ševčík, Radek

2016-01-01

Roč. 116, June (2016), s. 33-43 ISSN 1044-5803 R&D Projects: GA MŠk(CZ) LO1219 Keywords : fired- clay brick * Rietveld method * small angle neutron scattering * X-ray diffraction * firing temperature Subject RIV: AL - Art, Architecture, Cultural Heritage Impact factor: 2.714, year: 2016 http://www.sciencedirect.com/science/article/pii/S1044580316300870

REMOCION DE LA MATERIA ORGANICA Y TOXICIDAD EN AGUAS RESIDUALES HOSPITALARIAS APLICANDO OZONO

Directory of Open Access Journals (Sweden)

DAYANA GRISALES PENAGOS

2012-01-01

Full Text Available Las aguas residuales hospitalarias se consideran como una de las principales fuentes de contaminantes emergentes, resultado de las diferentes actividades que allí se realizan y la excreción de las sustancias por los pacientes. Estudios han demostrado que estos componentes no son fácilmente removidos por medio de procesos de tratamiento convencionales como las plantas de tratamiento que emplean procesos biológicos. En este sentido el propósito de este trabajo consistió en evaluar la degradación de la materia orgánica presente en aguas hospitalarias reales aplicando ozono en diferentes condiciones de pH (3,0, 6,7, 10. Para esto se analizaron los valores de la UV254, la relación de biodegradabilidad DQO/DBO5 y el color (VIS436. Adicional a esto, se realizó un ensayo de toxicidad aguda, utilizando bulbos de cebolla común (Allium cepa L. Los resultados mostraron que con una dosis aplicada de ozono de 187 mgO3/h y valores de pH=10 la biodegradabilidad se aumento en un 70% y la toxicidad aguda se redujo en 62%, mientras que para valores de pH =3,0, se favoreció la remoción de la UV254 y el color. La aplicación de ozono demostró ser una alternativa viable para tratar efluentes hospitalarios como pretratamiento de un proceso biológico.

Rietveld profile analysis of calcined AlPO/sub 4/-11 using pulsed neutron powder diffraction

Energy Technology Data Exchange (ETDEWEB)

Richardson, J.W. Jr.; Pluth, J.J.; Smith, J.V.

1988-08-01

Aluminium phosphate, AlPO/sub 4/, M/sub r/=121.95, orthorhombic, Icmm (disordered Al, P), Icm2 (ordered Al, P), a=13.5333(8), b=18.4845(10), c=8.3703(4) A, V=2094 A/sup 3/, Z=20, D/sub x/=1.93 g cm/sup -3/, T approx. = 295 K, R/sub wp/=0.031, R/sub F//sup 2/=0.109 (Icmm) and R/sub wp/=0.027, R/sub F//sup 2/=0.058 (Icm2) for 1017 independent reflections. Sample calcined at 873 K and dehydrated at 573 K. Time-of-flight neutron powder diffraction data were taken on the GPPD diffractometer at the Argonne National Laboratory Intense Pulsed Neutron Source. The structure was refined by Rietveld profile analysis in the range d=0.86-3.91 A in two space groups: Icmm assuming no ordering of Al and P, and Icm2 assuming strict alternation of Al and P on tetrahedral nodes. (orig./BHo).

Ambientes Virtuales Para la enseñanza de la Mecánica de Fluidos: Algunos ejemplos simplificados aplicando ANSYS

Directory of Open Access Journals (Sweden)

Watson L. Vargas

2005-01-01

Full Text Available Para que un ambiente de enseñanza virtual pueda soportar un aprendizaje real, dichos ambientes deben proveer interacciones enseñanza-aprendizaje de alto nivel. En este artículo, se muestra como una herramienta computacional como ANSYS puede proveer un ambiente virtual para el aprendizaje de la mecánica de fluidos no sólo a nivel de pregrado si no también a niveles superiores. Las simulaciones computacionales, --aplicando ANSYS/FLOTRAN-CFD o cualquiera otro software de capacidades similares--, en el contexto de la enseñanza de la mecánica de fluidos son de interés fundamental dado que soportan un ambiente de simulación poderoso que puede aplicarse no sólo a la comprensión de ideas y conceptos fundamentales sino tambien al diseño y optimización de procesos de aplicación práctica

Homogeneity characterisation of (U,Gd)O2 sintered pellets by X-ray diffraction powder analysis applying Rietveld method

International Nuclear Information System (INIS)

Leyva, Ana G.; Vega, Daniel R.; Trimarco, Veronica G.; Marchi, Daniel E.

1999-01-01

The (U,Gd)O 2 sintered pellets are fabricated by different methods. The homogeneity characterisation of Gd content seems to be necessary as a production control to qualify the process and the final product. The micrographic technique is the most common method used to analyse the homogeneity of these samples, this method requires time and expertise to obtain good results. In this paper, we propose an analysis of the X-ray diffraction powder patterns through the Rietveld method, in which the differences between the experimental data and the calculated from a crystalline structure model proposed are evaluated. This result allows to determine the cell parameters, that can be correlated with the Gd concentration, and the existence of other phases with different Gd ratio. (author)

Presence of a monoclinic (Pm) phase in the morphotropic phase boundary region of multiferroic (1 − x)Bi(Ni{sub 1/2}Ti{sub 1/2})O{sub 3}-xPbTiO{sub 3} solid solution: A Rietveld study

Energy Technology Data Exchange (ETDEWEB)

Pandey, Rishikesh, E-mail: akhilesh-bhu@yahoo.com, E-mail: aksingh.mst@itbhu.ac.in; Singh, Akhilesh Kumar, E-mail: akhilesh-bhu@yahoo.com, E-mail: aksingh.mst@itbhu.ac.in [School of Materials Science and Technology, Indian Institute of Technology (Banaras Hindu University), Varanasi 221005 (India)

2014-07-28

We present here the results of structural studies on multiferroic (1 − x)Bi(Ni{sub 1/2}Ti{sub 1/2})O{sub 3}-xPbTiO{sub 3} solid solution using Rietveld analysis on powder x-ray diffraction data in the composition range 0.35 ≤ x ≤ 0.55. The stability region of various crystallographic phases at room temperature for (1 − x)Bi(Ni{sub 1/2}Ti{sub 1/2})O{sub 3}-xPbTiO{sub 3} is determined precisely. Structural transformation from pseudo-cubic (x ≤ 0.40) to tetragonal (x ≥ 0.50) phase is observed via phase coexistence region demarcating the morphotropic phase boundary. The morphotropic phase boundary region consists of coexisting tetragonal and monoclinic structures with space group P4mm and Pm, respectively, stable in composition range 0.41 ≤ x ≤ 0.49 as confirmed by Rietveld analysis. The results of Rietveld analysis completely rule out the coexistence of rhombohedral and tetragonal phases in the morphotropic phase boundary region reported by earlier workers. A comparison between the bond lengths for “B-site cations-oxygen anions” obtained after Rietveld refinement, with the bond length calculated using Shannon-Prewitt ionic radii, reveals the ionic nature of B-O (Ni/Ti-O) bonds for the cubic phase and partial covalent character for the other crystallographic phases.

Application of the Rietveld method in powders of strontium-doped lanthanum manganite calcined in different temperatures

International Nuclear Information System (INIS)

Chiba, R.; Vargas, R.A.; Martinez, L.G.; Andreoli, M.; Seo, E.S.M.

2010-01-01

The strontium-doped lanthanum manganite (LSM) is a ceramic material used as cathode in device called High Temperature Solid Oxide Fuel Cell. In this work, the LSM was synthesized by the citrate technique with the objective to get powders without the formation of secondary phases, such as lanthanum oxide and the lanthanum hydroxide, harmful for the functional performance of the device. The definitive calcination temperatures had been 700, 900 and 1100 deg C, due the decomposition of the polymeric precursors to present stabilization from 480 deg C. The analysis by X-ray diffraction of the calcined powders in different temperatures shows the formation only of phase LSM of hexagonal crystalline structure, type pseudo-perovskite. Using the refinement of Rietveld was determined the parameters and volumes of unity cells, atomic positions and occupations. These results confirm that the chemical compositions obtained are similar to the nominal. (author)

Rietveld refinement and dielectric relaxation of a new rare earth based double perovskite oxide: BaPrCoNbO{sub 6}

Energy Technology Data Exchange (ETDEWEB)

Bharti, Chandrahas, E-mail: bharti.chandrahas@gmail.com [Sensor and Actuator Division, CSIR-Central Glass and Ceramic Research Institute, 196, Raja SC Mullick Road, Kolkata 700032 (India); Das, Mrinmoy K.; Sen, A. [Sensor and Actuator Division, CSIR-Central Glass and Ceramic Research Institute, 196, Raja SC Mullick Road, Kolkata 700032 (India); Chanda, Sadhan; Sinha, T.P. [Department of Physics, Bose Institute, 93/1, Acharya Prafulla Chandra Road, Kolkata-700009 (India)

2014-02-15

A new rare earth based double perovskite oxide barium praseodymium cobalt niobate, BaPrCoNbO{sub 6} (BPCN) is synthesized by solid-state reaction technique. Rietveld analysis of X-ray diffraction (XRD) data shows that the compound crystallizes in a perovskite like tetragonal structure which belongs to the I4/mmm space group with lattice parameters a=b=5.6828(9) Å, c=8.063(2) Å. Structural analysis reveals 1:1 ordered arrangement for the Co{sup 2+} and Nb{sup 5+} cations over the six-coordinate B-sites of BPCN. The superlattice line (1 0 1) at 2θ=19.10° arising from the alternate ordering of Co{sup 2+} and Nb{sup 5+} sites is observed in the XRD pattern which confirms the presence of cation ordering in BPCN. Fourier transform infrared spectrum shows two phonon modes of the sample due to the antisymmetric NbO{sub 6} stretching vibration. The relaxation dynamics of the conductive process in BPCN is investigated in the temperature range 303 to 503 K and in the frequency range 100 Hz to 1 MHz using impedance spectroscopy. The relaxation mechanism of the sample in the framework of electric modulus formalism is modeled by Davidson–Cole model (DCM). The values of α (distribution of relaxation time) for the DCM varies from 0.1 to 0.3 which suggests the asymmetric distribution of relaxation time for BPCN. The activation energy of the sample, calculated from both conductivity and modulus spectra, are found to be almost the same ∼0.4 eV, which indicates that the conduction mechanism for BPCN is polaron hopping. The scaling behaviour of the imaginary part of electric modulus suggests that the relaxation follows the same mechanism at various temperatures. - Graphical abstract: Rietveld refinement plot for BPCN. Inset shows the schematic presentation of the BPCN tetragonal unit cell. The Co{sup 2+} atoms are located at the centers of the CoO{sub 6} (blue) octahedra. The Nb{sup 5+} atoms are located at the centers of the NbO{sub 6} (green) octahedra. Display Omitted

Integración de procesos de negocio aplicando servicios web

Directory of Open Access Journals (Sweden)

Darío Picón

2014-09-01

Full Text Available La Integración de Procesos de Negocio (Business Process Integration – BPI, utiliza una gran cantidad de servicios distribuidos, por lo que la comunicación entre estos servicios es clave para el buen funcionamiento del sistema. En este modelo de cooperación, la arquitectura Cliente-Servidor tradicional ya no es suficiente para la implementación de soluciones que soporten comunicación entre aplicaciones distribuidas, independientemente de la plataforma y del lenguaje de programación que utilizan estas aplicaciones. Por su parte, las Arquitecturas Orientadas a Servicios (Service Oriented Architectures - SOA proveen una estructura que posibilita el modelado de procesos y conexiones interorganizacionales. Mientras que la Gestión de Procesos de Negocio (Business Process Management - BPM es el conjunto de sistemas de software, herramientas y metodologías para gestionar tales requerimientos y, el Lenguaje de Ejecución de Procesos de Negocio (Business Process Execution Language - BPEL, es un lenguaje de orquestación de servicios que permite definir la forma en que cooperan entre sí los Servicios Web para alcanzar la lógica de negocio. En este escenario, existen buenas herramientas para asistir desde lo conceptual y desde lo práctico a la Integración de Procesos de Negocio aplicando Servicios Web. Entonces, la problemática se plantea al momento de vincular estas herramientas de manera apropiada para facilitar el proceso de definición e implementación de este tipo de sistemas y en particular, en el ámbito de las pequeñas y medianas empresas (PyMEs.En este trabajo se propone un modelo que hace posible el BPI mediante Servicios Web de una manera ágil y practica, facilitando su implementación. El mismo será aplicado metodológicamente a un Caso de Estudio en el dominio de las PyMEs, con el propósito de evaluar su eficiencia, evidenciar sus beneficios y hallar oportunidades de mejora.

In-situ high-energy X-ray diffraction and batch Rietveld refinement of phase changes in titanium aluminides

International Nuclear Information System (INIS)

Whitfield, R.

2007-01-01

Full text: We have used the Rietveld refinement method for the analysis of high-energy X-ray power diffraction for quantitatve phase analysis. This method has the advantage of being able to model the multiple phases appearing in the diffraction pattern and tell us about the composition of the phases of a sample as we change the temperature. It has been applied to various TiAl compounds allowing us to follow in detail the phase transitions of the intermetallics when heated to around 1400 0 Cand subsequently cooled. Small amounts of additives like V, Cr and Gd as well as signatures from different production processes can be seen to have an effect on the phase transitions. With increasing temperature we can see the evolution of the unit cell due to thermal expansion, chemical segregation and the relative proportion of phase changes

Propuesta de mejora para la reducción de productos defectuosos en una planta de producción de neumáticos aplicando la metodología Six Sigma

OpenAIRE

Reinoso Vásquez, George

2016-01-01

La tesis se enfoca en desarrollar una propuesta de mejora para la reducción de productos defectuosos en una planta de producción de neumáticos aplicando la metodología Six Sigma desde el punto de vista de un sistema de mejora. Los expectativas de los clientes y el nivel de exigencia respecto a la calidad de los productos son cada vez mayores, esto obliga a las empresas busquen aumentar el valor percibido de sus productos como un elemento diferenciador y a la vez orienten sus...

Application of the Rietveld method in structural analysis of catalysts based on CuO/CeO{sub 2}; Aplicacao do metodo de Rietveld na analise estrutural de catalisadores a base de CuO/CeO{sub 2}

Energy Technology Data Exchange (ETDEWEB)

Neiva, L.S.; Ribeiro, M.A.; Bispo, A.; Simoes, A.N.; Gama, L., E-mail: lsoutoneiva@yahoo.com.br [Universidade Federal de Campina Grande (UFCG), PB (Brazil). Departamento de Engenharia de Materiais

2011-07-01

This work has as aim to synthesize catalysts composed by CuO/CeO{sub 2} by means two distinct methods of synthesis, they are: combustion synthesis and Pechini. The catalysts composed by CuO/CeO{sub 2} were synthesized with CuO in condition of dopant element. The value of the CuO concentration ranged between 0 and 0.5 mol. Has been done a structural analysis related to how the kind of synthesis method used influences over physical characteristic of the catalytic material. The obtained catalysts were characterized by X-ray diffraction with refinement by Rietveld method. According to results, the synthesized catalysts showed crystalline structures formed mostly by CeO{sub 2} phase, as expected, since this is the host matrix for the dopant element. The catalysts obtained by the Pechini method presented structures with a smaller amount of segregated phases formed by CuO, according to the results of the structural analysis. (author)

Analysis of Polymorphic Nanocrystals of TiO2 by X-Ray Rietveld Refinement and High-Resolution Transmission Electron Microscopy: Acetaldehyde Decomposition

Directory of Open Access Journals (Sweden)

R. Carrera

2008-01-01

Full Text Available In this work, TiO2 nanocrystals were synthesized by the sol-gel method. These materials were annealed at 200 and 500∘C; and characterized by the XRD-Rietveld refinement; and by BET and TEM. As for the low-temperature-treated sample (200∘C, nanocrystals with small crystallite sizes (7 nm and high abundance of anatase, coexisting with the brookite phase, were obtained. Meanwhile, the sample annealed at 500∘C showed an increased crystallite size (22 nm and an important polymorphic increment. The sample annealed at 200∘C showed a high activity in the photocatalytic decomposition of acetaldehyde.

Rietveld analysis using powder diffraction data with anomalous scattering effect obtained by focused beam flat sample method

International Nuclear Information System (INIS)

Tanaka, Masahiko; Katsuya, Yoshio; Sakata, Osami

2016-01-01

Focused-beam flat-sample method (FFM) is a new trial for synchrotron powder diffraction method, which is a combination of beam focusing optics, flat shape powder sample and area detectors. The method has advantages for X-ray diffraction experiments applying anomalous scattering effect (anomalous diffraction), because of 1. Absorption correction without approximation, 2. High intensity X-rays of focused incident beams and high signal noise ratio of diffracted X-rays 3. Rapid data collection with area detectors. We applied the FFM to anomalous diffraction experiments and collected synchrotron X-ray powder diffraction data of CoFe_2O_4 (inverse spinel structure) using X-rays near Fe K absorption edge, which can distinguish Co and Fe by anomalous scattering effect. We conducted Rietveld analyses with the obtained powder diffraction data and successfully determined the distribution of Co and Fe ions in CoFe_2O_4 crystal structure.

Assessment of firing conditions in old fired-clay bricks: The contribution of X-ray powder diffraction with the Rietveld method and small angle neutron scattering

Energy Technology Data Exchange (ETDEWEB)

Viani, Alberto, E-mail: viani@itam.cas.cz [Institute of Theoretical and Applied Mechanics AS CR, Centre of Excellence Telč, Batelovská 485, CZ-58856 Telč (Czech Republic); Sotiriadis, Konstantinos [Institute of Theoretical and Applied Mechanics AS CR, Centre of Excellence Telč, Batelovská 485, CZ-58856 Telč (Czech Republic); Len, Adél [Wigner Research Centre for Physics HAS, Konkoly-Thege 29-33, 1121 Budapest (Hungary); Šašek, Petr; Ševčík, Radek [Institute of Theoretical and Applied Mechanics AS CR, Centre of Excellence Telč, Batelovská 485, CZ-58856 Telč (Czech Republic)

2016-06-15

Full characterization of fired-clay bricks is crucial for the improvement of process variables in manufacturing and, in case of old bricks, for restoration/replacement purposes. To this aim, five bricks produced in a plant in Czech Republic in the past have been investigated with a combination of analytical techniques in order to derive information on the firing process. An additional old brick from another brickyard was also used to study the influence of different raw materials on sample microstructure. The potential of X-ray diffraction with the Rietveld method and small angle neutron scattering technique has been exploited to describe the phase transformations taking place during firing and characterize the brick microstructure. Unit-cell parameter of spinel and amount of hematite are proposed as indicators of the maximum firing temperature, although for the latter, limited to bricks produced from the same raw material. The fractal quality of the surface area of pores obtained from small angle neutron scattering is also suggested as a method to distinguish between bricks produced from different raw clays. - Highlights: • Rietveld method helps in describing microstructure and physical properties of bricks. • XRPD derived cell parameter of spinel is proposed as an indicator of firing temperature. • SANS effectively describes brick micro and nanostructure, including closed porosity. • Fractal quality of pore surface is proposed as ‘fingerprint’ of brick manufacturing.

Synthesis of Zr-Si-O-N phases by carbonitriding reaction. Characterization of crystalline phases using the Rietveld method

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Mazzoni A.D.

2001-01-01

Full Text Available Zirconium compounds are of great interest for ceramic application due to their excellent thermal and mechanical properties. Zirconium phases of the system Zr-O-C-N were obtained using carbonitriding reactions of zircon mineral (ZrO2.SiO2, under different reaction conditions. The reaction products were studied by X-ray diffraction (XRD using the Rietveld method. Silicon was employed as internal standard. Zirconium compounds formed were m-ZrO2 (monoclinic, beta"-zirconium oxynitride and a cubic Zr(C,N,O phase whose lattice parameter a o depends on the composition. The crystallite sizes of the three zirconium phases were determined also by XRD. The minority phases present are the ones of the Si-O-N-C system. The reaction conditions employed allows to obtain reaction products with low or without silicon content.

Rietveld structure refinement and elastic properties of MgAlxCrxFe2-2xO4 spinel ferrites

Science.gov (United States)

Thummer, K. P.; Tanna, Ashish R.; Joshi, Hiren H.

2017-05-01

MgAlxCrxFe2-2xO4 (x = 0.1, 03 & 0.6) ferrites are synthesized by solid state reaction method. The Rietveld refinement of X-ray diffraction (XRD) data confirms the cubic spinel structure with Fd3m space group. The Fourier Transform Infrared Transmission Spectroscopy (FTIR) is employed to study elastic properties of present systems at 300K. The force constants for tetrahedral (A) and octahedral (B) sites of the spinel lattice are determined by infrared spectral and X-ray diffraction analysis. The elastic constants like bulk modulus, rigidity modulus, Young's modulus, Poisson's ratio and Debye temperature are determined. The vibrational frequency of both the interstitial sites increases as Al-Cr content increases hence the force constant and elastic moduli for all the samples are found to increase for the present ferrite system.

Rietveld refinement and electronic structure studies for the Sm2FeMnO6 new complex perovskite

International Nuclear Information System (INIS)

Landinez Tellez, D.A.; Munevar, J.A.; Arbey Rodriguez, J.M.; Fajardo, F.; Roa-Rojas, J.

2008-01-01

We report synthesis and crystalline structure study of the Sm 2 FeMnO 6 new complex perovskite, by X-ray diffraction experiments and through the application of Rietveld refinement. Results revealed the crystallization of system in a structure given by Pmn21 (no. 31) space group and lattice parameters a=7.621(1) A, b=5.675(3) A and c=5.378(3) A. Ab initio calculations of density of states (DOS) and electronic structure were carried out for this perovskite-like system by the density functional theory (DFT) and using the full-potential linearized augmented plane waves (FP-LAPW) method. All calculations were carried out using spin polarization. Material evidences a conductor-like character, predominantly due to d-xy Fe orbital of the spin down channel. Magnetic response of system has contributions of Fe and Mn spin up orientation. The calculated magnetic moment in cell was 34.48 μ B and the magnetic moment in interstitial was 1.54 μ B

Rietveld analysis using powder diffraction data with anomalous scattering effect obtained by focused beam flat sample method

Energy Technology Data Exchange (ETDEWEB)

Tanaka, Masahiko, E-mail: masahiko@spring8.or.jp; Katsuya, Yoshio, E-mail: katsuya@spring8.or.jp; Sakata, Osami, E-mail: SAKATA.Osami@nims.go.jp [Synchrotron X-ray Station at SPring-8, National Institute for Materials Science 1-1-1 Kouto, Sayo, Hyogo 679-5198 (Japan)

2016-07-27

Focused-beam flat-sample method (FFM) is a new trial for synchrotron powder diffraction method, which is a combination of beam focusing optics, flat shape powder sample and area detectors. The method has advantages for X-ray diffraction experiments applying anomalous scattering effect (anomalous diffraction), because of 1. Absorption correction without approximation, 2. High intensity X-rays of focused incident beams and high signal noise ratio of diffracted X-rays 3. Rapid data collection with area detectors. We applied the FFM to anomalous diffraction experiments and collected synchrotron X-ray powder diffraction data of CoFe{sub 2}O{sub 4} (inverse spinel structure) using X-rays near Fe K absorption edge, which can distinguish Co and Fe by anomalous scattering effect. We conducted Rietveld analyses with the obtained powder diffraction data and successfully determined the distribution of Co and Fe ions in CoFe{sub 2}O{sub 4} crystal structure.

Application of the Rietveld method in structural analysis of catalysts based on CuO/CeO2

International Nuclear Information System (INIS)

Neiva, L.S.; Ribeiro, M.A.; Bispo, A.; Simoes, A.N.; Gama, L.

2011-01-01

This work has as aim to synthesize catalysts composed by CuO/CeO 2 by means two distinct methods of synthesis, they are: combustion synthesis and Pechini. The catalysts composed by CuO/CeO 2 were synthesized with CuO in condition of dopant element. The value of the CuO concentration ranged between 0 and 0.5 mol. Has been done a structural analysis related to how the kind of synthesis method used influences over physical characteristic of the catalytic material. The obtained catalysts were characterized by X-ray diffraction with refinement by Rietveld method. According to results, the synthesized catalysts showed crystalline structures formed mostly by CeO 2 phase, as expected, since this is the host matrix for the dopant element. The catalysts obtained by the Pechini method presented structures with a smaller amount of segregated phases formed by CuO, according to the results of the structural analysis. (author)

Crystal structures of new cuprates containing CO3 analyzed by the Rietveld method of neutron powder diffraction

International Nuclear Information System (INIS)

Miyazaki, Y.; Yamane, H.; Kajitani, T.; Hiraga, K.; Hirai, T.; Morii, Y.; Funahashi, S.

1993-01-01

New compounds containing CO 3 groups, Sr 2 CuO 2 (CO 3 ), (C 0.4 Cu 0.6 )Sr 2 (Y 0.86 Sr 0.14 )Cu 2 O 7 and (C 0.35 Cu 0.65 )Sr 2 (Y 0.73 Ce 0.27 ) 2 Cu 2 O 9 , were prepared as stable phases at 1273-1303 K in a flowing gas of O 2 -CO 2 . The crystal structures of these compounds were refined by means of the Rietveld analysis for neutron powder diffraction data collected using a high resolution powder diffractometer (HRPD) in the JRR-3M reactor hall of the Japan Atomic Energy Research Institute (JAERI). Positions of CO 3 groups were satisfactorily determined. The distances of C-O bonds in the CO 3 groups were around 1.3A and the O-C-O angles were almost equal to the ideal bond angle of 120deg. (author)

Rietveld refinement of the crystal structures of Rb2XSi5O12 (X = Ni, Mn

Directory of Open Access Journals (Sweden)

Anthony M. T. Bell

2016-02-01

Full Text Available The synthetic leucite silicate framework mineral analogues Rb2XSi5O12 {X = Ni [dirubidium nickel(II pentasilicate] and Mn [dirubidium manganese(II pentasilicate]} have been prepared by high-temperature solid-state synthesis. The results of Rietveld refinements, using X-ray powder diffraction data collected using Cu Kα X-rays, show that the title compounds crystallize in the space group Pbca and adopt the cation-ordered structure of Cs2CdSi5O12 and other leucites. The structures consist of tetrahedral SiO4 and XO4 units sharing corners to form a partially substituted silicate framework. Extraframework Rb+ cations sit in channels in the framework. All atoms occupy the 8c general position for this space group. In these refined structures, silicon and X atoms are ordered onto separate tetrahedrally coordinated sites (T-sites. However, the Ni displacement parameter and the Ni—O bond lengths suggest that for the X = Ni sample, there may actually be some T-site cation disorder.

Rietveld refinement and dielectric studies of Bi{sub 0.8}Ba{sub 0.2}FeO{sub 3} ceramic

Energy Technology Data Exchange (ETDEWEB)

Kaswan, Kavita, E-mail: kaswan.kavita@gmail.com; Agarwal, Ashish; Sanghi, Sujata; Rangi, Manisha; Jangra, Sandhaya; Singh, Ompal [Department of Applied Physics, Guru Jambheshwar University of Science and Technology, Hisar 125001, Haryana (India)

2016-05-23

Polycrystalline Bi{sub 0.8}Ba{sub 0.2}FeO{sub 3} ceramic has been synthesized via conventional solid state reaction technique. The Rietveld refinement of x-ray powder diffraction revealed that the sample has a rhombohedral crystal structure (space group R3c). With increase in temperature, the values of dielectric constant (ϵ′) and dielectric loss (tan δ) are found to be increase at different frequencies which may be the result of increase in the number of charge carriers and their mobilities due to the thermal activation. Further the ac conductivity data is analyzed by using Jonscher’s universal power law. The values of frequency exponent ‘s’ lies in the range 0.2 ≤ s ≤ 0.7 and decreases with increase in temperature which can be explained on the basis of CBH (Correlated Barrier Height) model.

Synthesis and refinement of ferroelectric ceramic BaBi4Ti4O15 (BBT) using Rietveld Methods

International Nuclear Information System (INIS)

Silva, P.M.O.; Sales, A.J.M.; Carneiro, J.C.S.; Sancho, E.O.; Sales, J.C.; Sombra, A.S.B.

2012-01-01

The lead zirconate titanate (PZT) has potential application in nonvolatile ferroelectric memory and capacitors, however this material is linked to environmental pollution. In order to remedy this problem, we propose the synthesis of the compound, BaBi 4 TI 4 O 15 (BBT) because of similarity to PZT. The phase of the BBT has been prepared by the method of solid state. Reagents (BaCO 3 , Bi 2 O 3 and TiO 2 ) were ground for 6 hours at 360 rpm in a planetary ball mill and suffered high energy heat treatment for 2 hours at temperatures of 850, 900, 950 and 1000 ° C. The calcined powder was characterized by X-ray diffraction (XRD) and refined by the program DBWSTools 2.3 Beta based on the Rietveld method. The results obtained confirmed the refinement of the single-phase with tetragonal structure BaBi 4 TI 4 O 15 for all samples. The sample calcined at 950 °C presented the best densification (7.508 g/cm³). (author)

Rietveld refinement of the structures of 1.0 C-S-H and 1.5 C-S-H

KAUST Repository

Battocchio, Francesco

2012-11-01

Low-Q region Rietveld analyses were performed on C-S-H synchrotron XRD patterns, using the software MAUD. Two different crystal structures of tobermorite 11 Å were used as a starting model: monoclinic ordered Merlino tobermorite, and orthorhombic disordered Hamid tobermorite. Structural modifications were required to adapt the structures to the chemical composition and the different interlayer spacing of the C-S-H samples. Refinement of atomic positions was done by using special constraints called fragments that maintain interatomic distances and orientations within atomic polyhedra. Anisotropic crystallite size refinement showed that C-S-H has a nanocrystalline disordered structure with a preferred direction of elongation of the nanocrystallites in the plane of the Ca interlayer. The quality of the fit showed that the monoclinic structure gives a more adequate representation of C-S-H, whereas the disordered orthorhombic structure can be considered a more realistic model if the lack of long-range order of the silica chain along the c-direction is assumed. © 2012 Elsevier Ltd. All rights reserved.

Rietveld refinement, dielectric and magnetic properties of Nb modified Bi0.80Ba0.20FeO3 ceramic

Science.gov (United States)

Jangra, Sandhaya; Sanghi, Sujata; Agarwal, Ashish; Rangi, Manisha

2018-05-01

Bi0.80Ba0.20Fe0.95Nb0.05O3 ceramic has been prepared via conventional solid state reaction method. Structure analysis was carried out by X-ray diffraction (XRD) technique at room temperature. XRD pattern confirmed the crystalline nature of prepared sample. Rietveld analysis used for further structural investigations and confirmed the existence of rhombohedral symmetry (R3c space group). The dielectric response shows dispersion at lower frequency range and becomes frequency independent at high frequency. The approximation of conduction mechanism is determined by the temperature dependent behavior of frequency exponent `s'. Fitting results suggests the applicability of small polaron conduction mechanism at lower temperatures and CBH model at higher temperature. Room temperature magnetic measurements give the evidence of significant enhancement in magnetic properties with remanent magnetization (Mr = 0.1218 emu/g) and coercive field (Hc = 3.5342 kOe).

Influence of diopside: feldspar ratio in ceramic reactions assessed by quantitative phase analysis (X-ray diffraction - Rietveld method)

International Nuclear Information System (INIS)

Kuzmickas, L.; Andrade, F.R.D.; Szabo, G.A.J.; Motta, J.F.M.; Cabral Junior, M.

2013-01-01

White ceramics were produced with raw mixtures prepared with varying proportions of diopside-rich rock (0 to 20 wt.%) and potassic feldspar (40 to 20 wt.%), and fixed proportions of kaolinite (40 wt.%) and quartz (20 wt.%), fired in a temperature range from 1170 to 1210 deg C. The phases identified in the experimental ceramics were quartz, anorthite, mullite and glass, and their relative mass proportions were determined by X-ray diffraction (Rietveld method). The addition of diopside as a partial substitute for potassic feldspar causes the formation of a calcium silicate, analogous of the natural anorthite (CaSi 2 Al 2 O 8 ) in the ceramics, with proportional reduction in its glass and mullite contents. Water absorption and porosity of the ceramic bodies clearly decrease with increasing firing temperature, while the effect of the raw mixture composition on the physical and mechanical properties of the ceramics is less evident. Diopside-rich rock has low iron content (1.5 wt.% Fe 2 O 3 ) and, therefore, promotes white burning. (author)

Influence of diopside: feldspar ratio in ceramic reactions assessed by quantitative phase analysis (X-ray diffraction - Rietveld method)

Energy Technology Data Exchange (ETDEWEB)

Kuzmickas, L.; Andrade, F.R.D.; Szabo, G.A.J. [Universidade de Sao Paulo (IGc/USP), SP (Brazil). Inst. de Geociencias. Dept. de Mineralogia e Geotecnia; Motta, J.F.M.; Cabral Junior, M., E-mail: lukuzmickas@gmail.com, E-mail: dias@usp.br, E-mail: gajszabo@usp.b, E-mail: motta.jf@gmail.com, E-mail: marsis@ipt.br [Instituto de Pesquisas Tecnologicas (IPT), Sao Paulo, SP (Brazil). Secao de Recursos Minerais e Tecnologia Ceramica

2013-04-15

White ceramics were produced with raw mixtures prepared with varying proportions of diopside-rich rock (0 to 20 wt.%) and potassic feldspar (40 to 20 wt.%), and fixed proportions of kaolinite (40 wt.%) and quartz (20 wt.%), fired in a temperature range from 1170 to 1210 deg C. The phases identified in the experimental ceramics were quartz, anorthite, mullite and glass, and their relative mass proportions were determined by X-ray diffraction (Rietveld method). The addition of diopside as a partial substitute for potassic feldspar causes the formation of a calcium silicate, analogous of the natural anorthite (CaSi{sub 2}Al{sub 2}O{sub 8}) in the ceramics, with proportional reduction in its glass and mullite contents. Water absorption and porosity of the ceramic bodies clearly decrease with increasing firing temperature, while the effect of the raw mixture composition on the physical and mechanical properties of the ceramics is less evident. Diopside-rich rock has low iron content (1.5 wt.% Fe{sub 2}O{sub 3}) and, therefore, promotes white burning. (author)

Preparation and Crystal Structures of Some AIVB2IIO4 Compounds: Powder X-Ray Diffraction and Rietveld Analysis

Directory of Open Access Journals (Sweden)

K. Jeyadheepan

2014-01-01

Full Text Available The AIVB2IIO4 compounds such as cadmium tin oxide (Cd2SnO4 or CTO and zinc tin oxide (Zn2SnO4 or ZTO are synthesized by solid state reaction of the subsequent binary oxides. The synthesized powders were analyzed through the powder X-ray diffraction (PXRD. Cell search done on the PXRD patterns shows that the Cd2SnO4 crystallizes in orthorhombic structure with space group Pbam and the cell parameters as a=5.568(2 Å, b=9.894(3 Å, and c=3.193(1 Å and the Zn2SnO4 crystallizes as cubic with the space group Fd3 -m and with the cell parameter a=8.660(2 Å. Rietveld refinement was done on the PXRD patterns to get the crystal structure of the Cd2SnO4 and Zn2SnO4 and to define the site deficiency of atoms which causes the electrical properties of the materials.

Study of effect of sintering time on the 2223 phase growth Bi-Pb-Sr-Ca-Cu-O superconductor by Rietveld method

International Nuclear Information System (INIS)

Parikin; Prasuad, W; Gunawan

1996-01-01

It has been reported that the sintering time is as important for the preparation of superconductor as the sintering temperature and method. This paper reports on the finding of the optimum sintering time in the preparation of the 2223 phase bismuth (Bi) superconductor. The samples were synthesized with nominal composition 1.84 : 0.34 : 1.91 : 2.03 : 3.06 from raw materials by solid state reaction and sintered at 860 o C for five days. The resintering were done three times, i.e. 24, 48 and 96 hours. The Rietveld analysis shows that the 2223 phase grows continuously as a function of the sintering time. The highest percentage of the 2223 phase (80.64%) were obtained at 96 hours sintering time. The result suggests that the 2223 phase can be obtained effectively by sintering with sufficiently long time

ESTUDIO DE LAS FASES MINERALÓGICAS DEL CLÍNKER EN UNA CEMENTERA ESPAÑOLA, UTILIZANDO EL MÉTODO DE RIETVELD

Directory of Open Access Journals (Sweden)

ANA M. CASTAÑÓN

2012-01-01

Full Text Available Con el objetivo de implantar un método de control de calidad de forma continua en una fábrica de cementos española, para mejorar las características del producto final, se están desarrollando nuevas metodologías de caracterización. El método de Rietveld [1] se ha utilizado con éxito para analizar la composición de las fases principales del clínker. Utilizando esta metodología, se ha llevado a cabo un estudio para cuantificar adecuadamente la fase minoritaria de Cal Libre, de gran importancia en la calidad del clínker. El método ha permitido obtener unos resultados satisfactorios en muestras cuyos contenidos superan el 3% de CaO. Estos resultados son posibles combinando adecuadamente las técnicas de difracción y fluorescencia de rayos-X, así como los resultados del análisis por vía química.

Influence of the milling time in the microstructural parameters of TA2O5-Al powder refined by Rietveld method

International Nuclear Information System (INIS)

Brito, R.A.; Mendes, M.W.D.; Alves Junior, C.; Costa, F.A. da; Gomes, U.U.

2009-01-01

Mechanical alloying (MA) is a solid-state powder processing technique involving repeated welding, fracturing, and re-welding of powder particles in a high energy mill. This process is used for producing of fine powders containing unique microstructures. The process starts with mixing of the powders in the desired proportion. Then, the mixture is milled using the established time in the high-energy mill. The powder particles are submitted to repeated cycles of cold working and fracture, and the final product correspond to a composite powder, containing characteristics different of the initial constituents. Ta 2 O 5 -Al powders were milled in a planetary ball mill for different times in order to evaluate the influence of the milling time in their microstructural parameters like crystallite size and micro deformation. The microstructural parameters were obtained by the Rietveld Method. The results showed that the microstructural parameters were influenced by the increase of the milling time. (author)

Crystal structure refinement of Ba5Nb4O15 and Ba5Nb4O15-x by Rietveld analysis of neutron and X-ray diffraction data

International Nuclear Information System (INIS)

Pagola, S.; Leyva, G.; Casais, M.T.; Alonso, J.A.; Rasines, I.; Carbonio, R.E.

1996-01-01

Both X-ray and neutron diffraction data were analyzed by the Rietveld method, taking as starting structural model that of the Ba 5 Ta 4 O 15 structure. The results of such an analysis show that the progressive elimination of oxygen ions produce only small changes in the structure. A decrease in the unit-cell parameters as the number of oxygen vacancies increases has been observed, which can be correlated with a gradual loss of oxygen ions in the close-packed layers. No ordering of the oxygen vacancies was found even in the sample with the highest x value, x=0.56. (orig.)

Study of selection and purification of Brazilian bentonite clay by elutriation: a XRF, SEM and Rietveld analysis

Energy Technology Data Exchange (ETDEWEB)

Alves, J.L.; Zanini, A.E.; Souza, M.E. de; Nascimento, M.L.F., E-mail: jeff_eq@yahoo.com.br, E-mail: mlfn@ufba.br [Universidade Federal da Bahia (UFBA/PROTEC/PEI), Salvador, BA (Brazil). Departamento de Engenharia Quimica

2016-01-15

Clays obtained from nature have a lot of impurities. Therefore, for best using of these materials, it is necessary its selection and purification. Thus, the aim of this work is to separate and to purify the smectite fractions using water as a solvent at a low flux mixed with a bentonite clay extracted from a mine in Vitoria da Conquista - Bahia / Brazil. For this a separation method of fractions of expandable clays based on the Stokes' Law was applied - this process is called elutriation, in order to ensure and to expand possible industrial applications of this material. The samples were characterized by analysis of X-ray diffraction, X-ray fluorescence and scanning electron microscopy. The Rietveld method enabled the quantification of main phase minerals: montmorillonite, kaolinite, nontronite and quartz, reaching 85% in mass of montmorillonite phase at the end of the process. Results showed that the method used was efficient to remove almost all quartz, carbonates and organic matter from the sample. It was also observed a monomodal grain size distribution of elutriated materials with thinner grains, around (18.1 ± 1.8) μm at the end of the process. It has been concluded that the method developed and applied showed promising characters to be applied to elutriate kilograms of clays and could be used in industrial scale. (author)

Study of selection and purification of Brazilian bentonite clay by elutriation: a XRF, SEM and Rietveld analysis

Directory of Open Access Journals (Sweden)

J. L. Alves

2016-03-01

Full Text Available Abstract Clays obtained from nature have a lot of impurities. Therefore, for best using of these materials, it is necessary its selection and purification. Thus, the aim of this work is to separate and to purify the smectite fractions using water as a solvent at a low flux mixed with a bentonite clay extracted from a mine in Vitória da Conquista - Bahia / Brazil. For this a separation method of fractions of expandable clays based on the Stokes' Law was applied - this process is called elutriation, in order to ensure and to expand possible industrial applications of this material. The samples were characterized by analysis of X-ray diffraction, X-ray fluorescence and scanning electron microscopy. The Rietveld method enabled the quantification of main phase minerals: montmorillonite, kaolinite, nontronite and quartz, reaching 85% in mass of montmorillonite phase at the end of the process. Results showed that the method used was efficient to remove almost all quartz, carbonates and organic matter from the sample. It was also observed a monomodal grain size distribution of elutriated materials with thinner grains, around (18.1 ± 1.8 μm at the end of the process. It has been concluded that the method developed and applied showed promising characters to be applied to elutriate kilograms of clays and could be used in industrial scale.

Study of selection and purification of Brazilian bentonite clay by elutriation: a XRF, SEM and Rietveld analysis

International Nuclear Information System (INIS)

Alves, J.L.; Zanini, A.E.; Souza, M.E. de; Nascimento, M.L.F.

2016-01-01

Clays obtained from nature have a lot of impurities. Therefore, for best using of these materials, it is necessary its selection and purification. Thus, the aim of this work is to separate and to purify the smectite fractions using water as a solvent at a low flux mixed with a bentonite clay extracted from a mine in Vitoria da Conquista - Bahia / Brazil. For this a separation method of fractions of expandable clays based on the Stokes' Law was applied - this process is called elutriation, in order to ensure and to expand possible industrial applications of this material. The samples were characterized by analysis of X-ray diffraction, X-ray fluorescence and scanning electron microscopy. The Rietveld method enabled the quantification of main phase minerals: montmorillonite, kaolinite, nontronite and quartz, reaching 85% in mass of montmorillonite phase at the end of the process. Results showed that the method used was efficient to remove almost all quartz, carbonates and organic matter from the sample. It was also observed a monomodal grain size distribution of elutriated materials with thinner grains, around (18.1 ± 1.8) μm at the end of the process. It has been concluded that the method developed and applied showed promising characters to be applied to elutriate kilograms of clays and could be used in industrial scale. (author)

Application of low current intensity electrolytic treatment for the chlorides extraction in underwater archaeological objects of iron. Observation of the mineralogical phases evolution through XRD-Rietveld

International Nuclear Information System (INIS)

Bethencourt, M.; Gil, M. L. A.; Fernandez-Lorenzo, C.; Santos, A.

2004-01-01

With the purpose of optimising a suitable methodology for the conservation of an archaeological object of iron, a low current intensities electrolytic treatment has been applied, to a piece of cast iron, proving to be effective in the extraction of chloride ions from the structure of akaganeite, principal corrosion product of iron in the marine medium. The monitoring of the electrolytic treatment has been proven by applying the Rietveld method to the patterns XRD of samples extracted from the corroded surface before and after the treatment. This method has permitted the unequivocal determination of the akaganeite and its chemical composition. This identification has been corroborated by means of SEM and EDS. After the electrolytic treatment, akaganeite was not present in the sample. (Author) 9 refs

Measurements of Residual Stresses In Cold-Rolled 304 Stainless Steel Plates Using X-Ray Diffraction with Rietveld Refinement Method

International Nuclear Information System (INIS)

Parikin; Killen, P; Rafterry, A.

2009-01-01

The determination of the residual stresses using X-ray powder diffraction in a series of cold-rolled 304 stainless steel plates, deforming 0, 34, 84, 152, 158, 175 and 196 % reduction in thickness has been carried out. The diffraction data were analyzed using the Rietveld structure refinement method. The analysis shows that for all specimens, the martensite particles are closely in compression and the austenite matrix is in tension. Both the martensite and austenite, for a sample reducing 34% in thickness (containing of about 1% martensite phase) the average lattice strains are anisotropic and decrease approximately exponential with an increase in the corresponding percent reduction (essentially phase content). It is shown that this feature can be qualitatively understood by taking into consideration the thermal expansion mismatch between the martensite and austenite grains. Also, for all cold-rolled stainless steel specimens, the diffraction peaks are broader than the unrolled one (instrumental resolution), indicating that the strains in these specimens are inhomogeneous. From an analysis of the refined peak shape parameters, the average root-mean square strain, which describes the distribution of the inhomogeneous strain field, was predicted. The average residual stresses in cold-rolled 304 stainless steel plates showed a combination effect of hydrostatic stresses of the martensite particles and the austenite matrix. (author)

Valoración de los Proyectos de Grado sobre Educación Ambiental en la Universidad, Aplicando la Hipótesis de Progresión

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Alba Leonilde Suárez Arias

2015-12-01

Full Text Available Este trabajo  aplica la hipótesis de progresión como metodología para  la valoración de los proyectos de grado de los estudiantes en Educación Ambiental en la Universidad. Se han analizado, los proyectos realizados por los  alumnos de  la licenciatura en Biología y Educación Ambiental, en la Universidad del Quindío, Colombia. Cuyo objetivo  tiene la  formación de profesores para los diferentes niveles educativos. La hipótesis de progresión permite valorar  el cambio conceptual  presentado en los proyectos de grado no como un proceso puntual sino como un proceso de evolución de los contenidos. La investigación  muestra que los Proyectos fin de grado de los estudiantes de Biología y educación Ambiental  valorados aplicando la hipótesis de progresión tienen una visión aditiva y poco fundamentada   sobre la  incorpora ración de  la educación ambiental  en el currículo

Desempenho hidráulico de sistema de irrigação por gotejamento aplicando água residuária de suinocultura

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Rafael Oliveira Batista

2012-11-01

Full Text Available Normal 0 21 false false false PT-BR X-NONE X-NONE A realização deste trabalho objetivou analisar o desempenho hidráulico de sistema de irrigação por gotejamento aplicando água residuária de suinocultura tratada. Foi montada uma estrutura hidráulica de avaliação, constituída de três tipos de gotejadores (G1, G2 e G3. Manteve-se a pressão de serviço no início das linhas laterais em 105 kPa, e quantificaram-se a intervalos de 20 h, as vazões dos gotejadores, até a obtenção de um tempo total de 160 h de operação do sistema. O nível de entupimento dos gotejadores foi obtido por meio do coeficiente de variação de vazão (CVQ. Com a aplicação da água residuária da suinocultura houve aumento do CVQ, ao longo do tempo de funcionamento, somente na subunidade com gotejador G2. Os gotejadores de maior vazão e menor comprimento de labirinto são menos suscetíveis ao entupimento. A formação de biofilme foi resultante da interação entre sólidos suspensos, enxofre e bactérias, consistindo no principal fator de entupimento parcial e total dos gotejadores.

Quantitative phase analysis of alumina/calcium-hexaluminate composites using neutron diffraction data and the Rietveld method

International Nuclear Information System (INIS)

Asmi, D.; Low, I.M.; O'Connor, B.H.; Kennedy, S.J.

2000-01-01

Full text: The Al 2 O 3 -CaO system is the basis of an important class of high-temperature refractories in the steel industry. It contains a number of stable intermediate compounds which include C 3 A, C 12 A 7 , CA, CA 2 , and CA 6 . These calcium aluminates are also important constituents of high alumina cement and have been used to produce high-strength and high-toughness ceramic-polymer composite materials. More recently, alumina composites containing 30 wt% CA 6 platelets have been developed by An et al which show characteristics of self-reinforcement and enhanced toughening through crack-bridging. In this paper, we describe the use of high-temperature neutron diffraction to monitor the in-situ phase formation and abundances of calcium aluminates (CA, CA 2 , and CA 6 ) in alumina composites containing 5-50 wt % CA 6 .at temperatures in the range 1000 - 1600 deg C. These composites were produced using reaction sintering of alumina and calcium oxide. For comparison purposes, control samples of pure α-alumina and CA 6 were also produced. Determination of relative phase abundances in these materials has been performed using the standardless Rietveld refinement method. Results show that the relative phase abundance of calcium aluminates in the composites increased with temperature and in proportion with the amount of calcium oxide present. The formation temperatures of CA, CA 2 , and CA 6 have been observed to occur at 1000 deg , 1200 deg, and ∼1350 deg C respectively, which agree well with results obtained from x-ray diffraction, synchrotron radiation diffraction and differential thermal analysis

Detección De Patrones De Deserción En Los Programas De Pregrado De La Universidad Mariana De San Juan De Pasto, Aplicando El Proceso De Descubrimiento De Conocimiento Sobre Base De Datos (Kdd) Y Su Implementación En Modelos MatemáTicos De Predicción

OpenAIRE

Argote, Ivan; Jimenez, Robinson

2016-01-01

La investigación titulada: “Detección de Patrones de Deserción en los Programas de Pregrado de la Universidad Mariana de San Juan de Pasto, aplicando el proceso de descubrimiento de conocimiento sobre base de datos (KDD) y su implementación en modelos matemáticos de predicción”. Es un proyecto que tiene como objetivo primordial Aportar al Proceso de Toma de Decisiones para disminuir los niveles Deserción Estudiantil en los programas de pregrado de la Universidad Mariana, mediante el descubrim...

Structural determination of new solid solutions [Y2-x Mx ][Sn2-x Mx ]O7-3x/2 (M = Mg or Zn by Rietveld method

Directory of Open Access Journals (Sweden)

Mohamed Douma

2010-12-01

Full Text Available New [Y2-x Mx][Sn2-x Mx]O7-3x/2 (0 ≤x≤ 0.30 for M = Mg and 0 ≤x≤ 0.36 for M = Zn solid solutions with the pyrochlore structure were synthesized via high-temperature solid-state reaction method. Powder X-ray diffraction (PXRD patterns and Fourier transform infrared (FT-IR spectra showed that these materials are new non-stoichiometric solid solutions with the pyrochlore type structure. The structural parameters for the solids obtained were successfully determined by Rietveld refinement based on the analysis of the PXRD diagrams. Lattice parameter (a of these solid solutions decreases when x increases in both series. All samples obtained have the pyrochlore structure Fd-3m, no. 227 (origin at center -3m with M2+ (M = Mg2+ or Zn2+ cations in Y3+ and Sn4+ sites, thus creating vacancies in the anionic sublattice.

Descontaminación microbiana de la maca (Lepidium meyenii aplicando el sistema de esterilización orgánica (OSS para preservar sus propiedades nutricionales y sensoriales

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Américo Guevara Pérez

2016-01-01

Full Text Available La investigación tuvo como objetivo aplicar el sistema de esterilización orgánica (OSS en maca, determinando los parámetros del proceso: tiempo y temperatura de inyección de vapor saturado que reduzcan el recuento de microorganismos aerobios, mohos, levaduras, E. Coli, salmonella y coliformes totales, y evaluando la influencia del proceso en el contenido total de glucosinolatos. La máxima descontaminación microbiana de la maca se logró aplicando una carga de 5 kg/saquillo, por 6 min. Con una temperatura de inyección de vapor saturado de 100 °C. Bajo estas condiciones, la reducción de la carga microbiana fue de 99,9% (< 10 UFC/g, 50% (< 10 UFC/g y 93,3% (< 10 UFC/g para aerobios, mohos, y levaduras, respectivamente; el comportamiento de patógenos fue muy similar al de la materia prima: E. coli < 3 UFC/g, ausencia de salmonella (25 g y < 3 UFC/g para coliformes totales. El contenido de glucosinolatos se mantuvo durante el proceso en 1,5 μmol/g, lo que evidenció que al aplicar la tecnología OSS se logra conservar la calidad nutricional, sensorial y funcional de la maca.

X-ray diffraction analysis of stan nite, wurtz-stan nite and pseudo-cubic quaternary compounds by Rietveld method

Energy Technology Data Exchange (ETDEWEB)

Quintero, M.; Quintero, E.; Moreno, E.; Alvarez, S.; Rincon, C.; Grima, P.; Bocaranda, P.; Rivero, D. [Universidad de Los Andes, Centro de Estudios de Semiconductores, 5101 Merida (Venezuela, Bolivarian Republic of); Marquina, J. [Universidad de Los Andes, Centro de Estudios Avanzados en Optica, 5101 Merida (Venezuela, Bolivarian Republic of); Henao, J. A.; Macias, M. A., E-mail: mquinterg@gmail.com [Universidad Industrial de Santander, Facultad de Ciencias, Escuela de Quimica, Grupo de Investigacion en Quimica Estructural, Apdo. Aereo 678, Bucaramanga (Colombia)

2014-07-01

Room temperature X-ray powder diffraction measurements were carried out on nine polycrystalline samples of the Cu{sub 2}B{sup II}C{sup IV}X{sub 4} (B=Mn, or Fe, or Co; C=Si, or Ge, or Sn; X=S, or Se or Te) magnetic semiconductor compounds. The diffraction patterns were used to show the equilibrium conditions and to derive crystalline parameters values. The results showed that four of these compounds have a tetragonal stan nite structure with space group 142 m(N{sup o} 121), two and orthorhombic wurtz-stan nite structure with space group Pmn2{sub 1}(N{sup o} 31) and three of them and orthorhombic pseudo-cubic structure with space group F222 (N{sup o} 22). In each case, the structure was refined using the Rietveld method. When the obtained atomic parameter values for the tetragonal compounds were plotted as a function of molecular weight W, it was found that the values of the atomic positions, the cation-anion bond distances, tetragonal distortion and internal distortion of the compounds containing S and /or Se lay on different lines. Also, it was found that when the experimental points of the cation-anion bond distances d{sub Cu-VI}, d{sub II-VI} and d{sub IV-VI} were plotted against the effective lattice parameter a{sub c} = (V/N){sup 1/3}, a linear variation of these distances with a{sub c} was obtained. Values of the ionic energy gap C{sub i} and homopolar energy gap E{sub h} using the Phillips-Van Vechten scheme, with the present experimental crystallographic results as well as using the atomic data, were determined. It was found that the observed and predicted values of C{sub i} and E{sub h} lie on the same straight line. (Author)

Rietveld refinement of the crystal structure of perovskite solar cells using CH3NH3PbI3 and other compounds

Science.gov (United States)

Ando, Yuji; Ohishi, Yuya; Suzuki, Kohei; Suzuki, Atsushi; Oku, Takeo

2018-01-01

The crystal structures of perovskite thin films including CH3NH3PbI3, CH3NH3Pb1-xSbxI3, and CH3NH3PbI3-yCly in the solar cell configuration were studied by using Rietveld refinement. For the CH3NH3PbI3 and CH3NH3Pb1-xSbxI3 samples, satisfactory agreement with the measured profiles was obtained with a weighted profile R-factor (Rwp) of as low as 3%. It was shown that the site occupancy of methylammonium (MA) was decreased in the antimonized cell due to the compensation effect of an increased positive charge brought about by replacing Pb2+ with Sb3+. Photovoltaic measurements showed that the power conversion efficiency was enhanced by adding a small amount of Sb to the CH3NH3PbI3 cell, but it was monotonically decreased as the mole fraction of Sb exceeded 0.03. This variation of the conversion efficiency was considered as a result of suppressed crystallization of PbI2 and carrier recombination via MA vacancies in the antimonized cells. In the case of CH3NH3PbI2.88Cl0.12 sample, the agreement with the measured profile with an Rwp of as high as 7% suggested the co-existence of cubic and tetragonal phases in the chlorinated cell.

Rietveld refinement and dielectric properties of (Na{sub 0.5}Bi{sub 0.5}TiO{sub 3})-(Bi{sub 0.8}Ba{sub 0.2}FeO{sub 3}) ceramics

Energy Technology Data Exchange (ETDEWEB)

Kaswan, Kavita, E-mail: kaswan.kavita@gmail.com; Agarwal, Ashish; Sanghi, Sujata; Singh, Ompal [Department of Applied Physics, Guru Jambheshwar University of Science and Technology, Hisar-125001 (India)

2015-06-24

(1-x)(Na{sub 0.5}Bi{sub 0.5}TiO{sub 3})-x(Bi{sub 0.8}Ba{sub 0.2}FeO{sub 3}) lead free ceramics (NBT, NBT-BBFO; x = 0.0, 0.1 respectively) have been synthesized by conventional solid state reaction method. Crystalline phase of sintered ceramics was investigated at room temperature using X-ray diffraction. Rietveld refinement of XRD data performed by FullProf revealed that both the samples exhibited rhombohedral structure with R3c space group. Dielectric properties of these ceramics were studied at different temperatures in a wide frequency range using impedance analyzer. Dielectric constant and dielectric loss were found to be increase with increase of BBFO content. The prepared ceramics exhibit a broad maximum in dielectric permittivity at 593K and dispersive permittivity at high temperatures. The NBT-BBFO sample shows a relaxor ferroelectric behavior at different frequencies.

In situ X-ray Rietveld analysis of Ni-YSZ solid oxide fuel cell anodes during NiO reduction in H2

International Nuclear Information System (INIS)

Reyes Rojas, A; Esparza-Ponce, H E; Fuentes, L; Lopez-Ortiz, A; Keer, A; Reyes-Gasga, J

2005-01-01

A synthesis and characterization of solid oxide fuel cell (SOFC) anodes of nickel with 8%mol yttrium stabilized zirconia (Ni-YSZ) is presented. Attention was focused on the kinetics and phase composition associated with the transformation of NiO-YSZ to Ni-YSZ. The anodes were prepared with an alternative synthesis method that includes the use of nickel acetylacetonate as an inorganic precursor to obtain a highly porous material after sintering at 1400 deg. C and oxide reduction (NiO-YSZ → Ni-YSZ) at 800 deg. C for 8 h in a tubular reactor furnace using 10% H 2 /N 2 . The obtained material was compressed by unidirectional axial pressing into 1 cm-diameter discs with 15-66 wt% Ni and calcinated from room temperature to 800 deg. C. A heating rate of 1 deg. C min -1 showed the best results to avoid any anode cracking. Their structural and chemical characterization during the isothermal reduction were carried out by in situ time-resolved X-ray diffraction, refined with the Rietveld method (which allowed knowing the kinetic process of the reduction), scanning electron microscopy and X-ray energy dispersive spectroscopy. The results showed the formation of tetragonal YSZ 8%mol in the presence of nickel, a decrement in the unit cell volume of Ni and an increment of Ni in the Ni-YSZ anodes during the temperature reduction. The analysis indicated that the Johnson-Mehl-Avrami equation is unable to provide a good fit to the kinetics of the phase transformation. Instead, an alternative equation is presented

Cuantificación de plaguicidas residuales en granos de maíz (Zea mays L. aplicando técnicas de evaluación residual

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Dante Rojas

2014-07-01

Full Text Available El empleo de plaguicidas en la producción agrícola ha tomado marcada importancia para muchos sectores de la sociedad. Los productores agropecuarios necesitan realizar un tratamiento fitoterapeútico efectivo y la utilización de estos agroquímicos es una alternativa rentable. Sin embargo, la toxicidad de estas sustancias presenta un riesgo para la salud humana durante su fabricación y empleo. El objetivo del presente trabajo fue obtener información de los niveles y frecuencia de los principales residuos de pesticidas presentes en granos de maíz aplicando técnicas de evaluación multiresidual. El muestreo (basado en la Norma ISO 950:1979 fue realizado en cintas de embarque y terminales portuarias del Río Paraná y del sur de la Provincia de Buenos Aires (Argentina, dado que manejan más del 80 % de las exportaciones del país (Ingeniero White, Rosario/General San Martín/San Lorenzo, Villa Constitución y Quequén. Sobre un total de 192 muestras, 94 presentaron residuos de plaguicidas, siendo el orden de frecuencia de aparición de los mismos: fenitrotión (n = 40 > cipermetrina (n = 31 > pirimifós metil (n = 27 > deltametrina (n = 24 > clorpirifós metil (n = 23 > diclorvós (n = 18 > permetrina (n = 15 > clorpirifós etil (n = 12 > fenvalerato (n = 3 > malatión (n = 2 > endosulfán (n = 0; suma de alfa endosulfán, beta endosulfán y endosulfán sulfato. No se hallaron organoclorados. Considerando la legislación Argentina, solo 4 muestras presentaron niveles superiores a los Límites Máximos de Residuos (LMR, siendo cipermetrina el plaguicida involucrado. Sin embargo, según los LMR del Codex Alimentarius, todas las muestras presentaron niveles permitidos.

Cuantificación de plaguicidas residuales en granos de maíz (Zea mays L. aplicando técnicas de evaluación residual

Directory of Open Access Journals (Sweden)

Dante Rojas

2014-06-01

Full Text Available El empleo de plaguicidas en la producción agrícola ha tomado marcada importancia para muchos sectores de la sociedad. Los productores agropecuarios necesitan realizar un tratamiento fitoterapeútico efectivo y la utilización de estos agroquímicos es una alternativa rentable. Sin embargo, la toxicidad de estas sustancias presenta un riesgo para la salud humana durante su fabricación y empleo. El objetivo del presente trabajo fue obtener información de los niveles y frecuencia de los principales residuos de pesticidas presentes en granos de maíz aplicando técnicas de evaluación multiresidual. El muestreo (basado en la Norma ISO 950:1979 fue realizado en cintas de embarque y terminales portuarias del Río Paraná y del sur de la Provincia de Buenos Aires (Argentina, dado que manejan más del 80 % de las exportaciones del país (Ingeniero White, Rosario/General San Martín/San Lorenzo, Villa Constitución y Quequén. Sobre un total de 192 muestras, 94 presentaron residuos de plaguicidas, siendo el orden de frecuencia de aparición de los mismos: fenitrotión (n = 40 > cipermetrina (n = 31 > pirimifós metil (n = 27 > deltametrina (n = 24 > clorpirifós metil (n = 23 > diclorvós (n = 18 > permetrina (n = 15 > clorpirifós etil (n = 12 > fenvalerato (n = 3 > malatión (n = 2 > endosulfán (n = 0; suma de alfa endosulfán, beta endosulfán y endosulfán sulfato. No se hallaron organoclorados. Considerando la legislación Argentina, solo 4 muestras presentaron niveles superiores a los Límites Máximos de Residuos (LMR, siendo cipermetrina el plaguicida involucrado. Sin embargo, según los LMR del Codex Alimentarius, todas las muestras presentaron niveles permitidos.

Formação de biofilme em gotejadores aplicando água residuária da despolpa dos frutos do cafeeiro = Formation of biofilm in drippers applying wastewater from pulping of the coffee fruits

Directory of Open Access Journals (Sweden)

Rafael Oliveira Batista

2007-07-01

Full Text Available Este trabalho teve por objetivo analisar a formação de biofilme em sistemas de irrigação por gotejamento aplicando água residuária da despolpa dos frutos do cafeeiro (ARC submetidas ou não à passagem em filtro orgânico. Para isso, foi montada uma estrutura hidráulica de avaliação, constituída de fitas gotejadores, não autocompensantes e posicionados no espaçamento de 0,3 m. Diante dos resultados obtidos, pode-se concluir que: águas residuárias da despolpa de frutos do cafeeiro apresentaram severo risco de entupimento de gotejadores, mesmo quando submetidas a tratamento prévio em filtros orgânicos.This work objectified to analyze the formation of biofilm in drip irrigation systems applying wastewater from pulping of the coffee fruits (ARC with and without ticket in organic filter. For that, a hydraulic structure of evaluation, constituted of drip tape, non pressure compensating, positioned in the spacing of 0,3 m. In accordance with the results obtained can be concluded that: wastewater from pulping of the coffee fruits presented severe risk of clogging of emitters, same when submitted the treatment in organic filters.

Structure of the new Tl(Ba sub 1.0 Sr sub 1.0) PrCu sub 2 O sub 7-x by Rietveld analysis

International Nuclear Information System (INIS)

Yang, P.; Fun, H. K.; Lee, T.J.; Ku, H.C.; Lai, C.C.

1994-01-01

The crystalline structure of Tl(Ba sub 1.0 Sr sub 1.0)PrCu sub 2 O sub 7-x was obtained at room temperature from x-ray powder diffraction with CuK sub α radiation using Rietveld analysis. Tl(Ba sub 1.0 Sr sub 1.0)PrCu sub 2 O sub 7-x isomorphous at both room temperature (300 K) and low temperature (100 K) with TlBa sub 2 ca Cu sub 2 O sub 7-x type (1212) structure, crystallized with space group P4/mmm and one formula in the unit cell. At 300 K, cell parameters a=3.8892(2) A, c=12.3099(6) A, the structure was refined with 25 parameters to R sub WP = 6.30%, R sub P = 4.38% for 3551 step intensities and R sub b = 5.01%, R sub f = 4.20% for 156 reflections. The goodness of fitting S=3.18. At 100K, cell parameters a=3.8866(4) A, c= 12.289(1) A, the structure was refined with 26 parameters to R sub WP = 8.42%, R sub P = 6.21% for 2676 step intensities and R sub b = 6.72%, R sub f = 5.28% for 120 reflections. The goodness of fitting S=2.32. Reasonable anisotropic thermal parameters were obtained. The compositions of Ba and Sr atoms were refined to about Ba sub 1.1 Sr sub 0.9 compared with the stoichiometric Ba sub 1.0 Sr sub 1.0

The new insight into the structure-activity relation of Pd/CeO2-ZrO2-Nd2O3 catalysts by Raman, in situ DRIFTS and XRD Rietveld analysis.

Science.gov (United States)

Yang, X; Yang, L; Lin, J; Zhou, R

2016-01-28

Pd/CeO2-ZrO2-Nd2O3 (CZN) catalysts with different CeO2/ZrO2 molar ratios were synthesized and have been characterized by multiple techniques, e.g. XRD in combination with Rietveld refinement, UV-Raman, XPS and in situ DRIFTS. The XRD pattern of CZN with CeO2/ZrO2 molar ratios ≥1/2 can be indexed satisfactorily to the fluorite structure with a space group Fm3̄m, while the XRD patterns of CZ12 only display diffraction peaks of the tetragonal phase (S.G. P42/nmc). Nd addition can effectively stabilize the cubic structure of the CZN support and increase the enrichment of defect sites on the surface, which may be related to the better catalytic activity of Pd/CZN12 catalysts compared with Pd/CZ12. The presence of moderate ZrO2 can increase the concentration of O* active species, leading to accelerate the formation of nitrate species and thus enhance the catalytic activity of NOx and HC elimination. The Pd-dispersion decreases with the increasing Zr content, leading to the decreased CO catalytic activity, especially for the aged catalysts. The change regularity of the OSC value is almost the same with the in situ dynamic operational window, demonstrating that the in situ dynamic operational window is basically affected by the OSC value.

Aplicación de diversos métodos químicos para determinar actividad antioxidante en pulpa de frutos Aplicação de diversos métodos químicos para determinar atividade antioxidante em polpa de frutas

Directory of Open Access Journals (Sweden)

E. Marta Kuskoski

2005-12-01

Full Text Available El Brazil es considerado un de los principales países productores de zumos de frutos, ocupando en concreto la tercera posición respecto a esto. La diversidad de frutos en el mercado es cada vez mayor, introduciéndose diariamente nuevos frutos tropicales cuyas propiedades y actividades no están aún totalmente determinadas. El gobierno brasileño apoya el comercio exterior de frutos, invirtiendo fondos en exposiciones que promueven y sitúan a los nuevos productos en los países de la Unión Europea, tal como la "Brazilian Fruit Festival" que promociona frutos in natura, pulpas congeladas y zumos procesados. Se publican cada vez en mayor número nuevas investigaciones que asocian el consumo de frutas con efectos beneficiosos para la salud humana. Este trabajo tiene por objeto la determinación del índice de fenoles totales (FT, antocianos totales (AT y la capacidad antioxidante de las pulpas de frutos comerciales congelados, aplicando los métodos espectrofotométrico químicos mas en boga para la determinación de la actividad antioxidante (ABTS, DPPH y DMPD. Se ha determinado la capacidad antioxidante de las pulpas de los frutos tropicales de mayor consumo en el mercado del sur de Brazil (mora, uva, açaí, guayaba, fresa, acerola, piña, mango, graviola, cupuaçu y maracuyá aplicando el método ABTS con medidas a dos tiempos (1 y 7 minutos, DPPH (30 y 60 minutos y DMPD (10 minutos. Los valores TEAC (capacidad antioxidante equivalente al Trolox obtenidos de las pulpas oscilan entre mínimos y máximos de 2,0 y 67,2 µmol/g aplicando el ensayo ABTS, 1,02 y 67,0 µmol/g aplicando DPPH y 4,2 y 46,6 µmol/g aplicando DMPD. La capacidad antioxidante obtenida por los métodos ABTS y DPPH se encuentra correlacionada con el contenido de compuestos fenólicos y antocianos.Considerado um dos principais paises produtores de sucos de frutas, o Brasil é o terceiro maior produtor de frutas tropicais. A diversidade de frutas no mercado é cada vez

The analysis of powder diffraction data

International Nuclear Information System (INIS)

David, W.I.F.; Harrison, W.T.A.

1986-01-01

The paper reviews neutron powder diffraction data analysis, with emphasis on the structural aspects of powder diffraction and the future possibilities afforded by the latest generation of very high resolution neutron and x-ray powder diffractometers. Traditional x-ray powder diffraction techniques are outlined. Structural studies by powder diffraction are discussed with respect to the Rietveld method, and a case study in the Rietveld refinement method and developments of the Rietveld method are described. Finally studies using high resolution powder diffraction at the Spallation Neutron Source, ISIS at the Rutherford Appleton Laboratory are summarized. (U.K.)

Rietveld refinement of the orthorhombic Pbca structures of Rb2CdSi5O12, Cs2MnSiO5O12, Cs2CoSi5O12 and Cs2NiSi5O12 leucites by synchrotron X-ray powder diffraction

International Nuclear Information System (INIS)

Bell, A.M.T.; Henderson, C.M.B.

1996-01-01

Analysis of high-resolution synchrotron X-ray powder diffraction patterns for hydrothermally synthesized Rb 2 CdSi 5 O 12 and Cs 2 MnSi 5 O 12 leucite analogues, and dry-synthesized Cs 2 CoSi 5 O 12 and Cs 2 NiSi 5 O 12 leucite analogues showed that they have an orthorhombic Pbca structure. The structures have been refined by the Rietveld method, showing that the tetrahedrally coordinated atoms (Si, Cd, Mn, Co and Ni) are ordered on separate sites. The Cs 2 MnSi 5 O 12 , Cs 2 CoSi 5 O 12 and Cs 2 NiSi 5 O 12 leucite samples are unusual in containing SiO 4 tetrahedra which are more distorted, on average, than the larger MnO 4 , CoO 4 and NiO 4 tetrahedra. The JCPDS file numbers for Rb 2 CdSi 5 O 12 , Cs 2 MnSi 5 O 12 and Cs 2 CoSi 5 O 12 are 46-1491, 46-1492 and 46-1493, respectively. (orig.)

Implementation of GASBOL advanced functions; Implantacao do sistema de funcoes avancadas do GASBOL

Energy Technology Data Exchange (ETDEWEB)

Valeriano, Alexsander; Frota, Cristiane Souto [TBG - Transportadora Brasileira Gasoduto Bolivia Brasil S.A., Rio de Janeiro, RJ (Brazil); Frisoli, Caetano [TRANSPETRO - PETROBRAS Transporte S.A., Rio de Janeiro, RJ (Brazil)

2003-07-01

Real time simulation tools for gas pipelines are already a reality in control central rooms, providing safer and more efficient operations, complementing SCADA functionalities for gas pipeline supervision and monitoring. Different modules can compose this set of tools, also named Advanced Functions, for example: real time monitoring module; predictive module, used for operational strategies, planning for future operations and what if sceneries simulation; look ahead module, used to warn the operator for operational situations that might occur in the future; training simulator, used for operators training and qualification, among others. The application of these tools by natural gas transporter companies, seen as an important tool of decision and support to the operation team, increases the quality of services and creates a differential against market competitors. (author)

Efeitos do período e volume de aplicação na segurança dos tratoristas aplicando herbicidas na cultura de cana-de-açúcar (Saccharum spp. Effects of herbicide spraying period and volume on the safety of tractor drivers spraying herbicides on sugarcane (Saccharum spp. crop

Directory of Open Access Journals (Sweden)

J.C. Momesso

2003-12-01

Full Text Available O objetivo deste trabalho foi avaliar os efeitos do período e volume de aplicação na segurança da atividade de tratoristas aplicando herbicidas na cultura de cana-de-açúcar com o pulverizador de barra montado em trator e a eficiência de equipamentos de proteção individual (EPIs e de uma cabina acoplada ao trator. As exposições dérmicas de 13 condições de trabalho foram avaliadas e analisadas estatisticamente por meio do delineamento inteiramente ao acaso e do esquema fatorial 3 x 2 x 2 + 1. O fator A foi a condição de exposição: 1 exposição dérmica potencial (EDP - sem nenhuma medida de segurança; 2 exposição com cabina no trator (Cabina; e 3 exposição com as vestimentas (EPI. O fator B foi o volume de aplicação: 1 200 L ha-1 e 2 100 L ha-1; e o fator C foi o período de aplicação: 1 diurno e 2 noturno. Como testemunha foi avaliada a EDP do tratorista aplicando na atividade usual de 300 L de calda ha-1, no período diurno. As exposições dérmicas (EDs aos herbicidas considerados nessas condições de trabalho foram estimadas por meio de dados substitutos das EDs avaliadas ao cátion Cu+2 adicionado como traçador nas caldas aplicadas. O pulverizador utilizado foi do modelo PJ 600, com barra de 12 m de comprimento e 24 bicos de jato plano TT 110 04 ou TT 110 02. As 13 condições de trabalho avaliadas foram classificadas como seguras (MS>1 para o tratorista aplicando os herbicidas glyphosate (48% i.a., MSMA (48%, diuron (46,8% + hexazinone (13,2%, clomazone (50%, sulfentrazone (50%, ametryne (50%, diuron (50%, isoxaflutole (75%, metribuzin (48%, 2,4-D (80,6%, ametryne (30% + clomazone (20%, ametryne (73,25% + trifloxysulfuron (1,85% e tebuthiuron (80 % e inseguras para o herbicida atrazine (50%, nos dois períodos e nos três volumes de aplicação, e ametryne (50%, na aplicação diurna e 100 L de calda ha-1. As aplicações noturnas e os volumes de aplicação reduzidos tornaram as condições de trabalho mais

The formation and structure of mechano-synthesized nanocrystalline Sr{sub 3}Fe{sub 2}O{sub 6.4}: XRD Rietveld, Mössabuer and XPS analyses

Energy Technology Data Exchange (ETDEWEB)

Al-Rawas, A.D., E-mail: arawas@squ.edu.om [Department of Physics, Sultan Qaboos University, P.O. Box 36, 123 Al-Khoud, Muscat (Oman); Widatallah, H.M.; Al-Harthi, S.H. [Department of Physics, Sultan Qaboos University, P.O. Box 36, 123 Al-Khoud, Muscat (Oman); Johnson, C. [Chemistry Department, Open University, Walton Hall, Milton Keynes MK7 6AA (United Kingdom); Gismelseed, A.M.; Elzain, M.E.; Yousif, A.A. [Department of Physics, Sultan Qaboos University, P.O. Box 36, 123 Al-Khoud, Muscat (Oman)

2015-05-15

Highlights: • The formation of mechano-synthesized nanocrystalline Sr{sub 3}Fe{sub 2}O{sub 7−δ} is investigated. • Pre-milling the reactants substantially lowers the formation temperature. • The core and surface structures were studied. • XRD and {sup 57}Fe Mössbauer spectroscopic analyses indicate the δ-value to be 0.60. • XPS shows a complex surface structure for the mechanosynthesized Sr{sub 3}Fe{sub 2}O{sub 7−δ} nanoparticles. - Abstract: The influence of ball milling and subsequent sintering of a 3:1 molar mixture of SrCO{sub 3} and α-Fe{sub 2}O{sub 3} on the formation of Sr{sub 3}Fe{sub 2}O{sub 7−δ} double perovskite is investigated with different analytical techniques. Milling the mixture for 110 h leads to the formation of SrCO{sub 3}-α-Fe{sub 2}O{sub 3} nanocomposites and the structural deformation of α-Fe{sub 2}O{sub 3} via the incorporation of Sr{sup 2+} ions. Subsequent sintering of the pre-milled reactants’ mixture has led to the partial formation of an SrFeO{sub 3} perovskite-related phase in the temperature range 400–600 °C. This was followed by the progressive development of an Sr{sub 3}Fe{sub 2}O{sub 7−δ} phase that continued to increase with increasing sintering temperature until a single-phased nanocrystalline Sr{sub 3}Fe{sub 2}O{sub 7−δ} phase was attained at 950 °C (12 h). This temperature is ∼350 °C lower than the temperature at which the material is prepared conventionally using the ceramic method. The evolution of different structural phases during the reaction process is discussed. Rietveld refinement of the X-ray diffraction data shows a value of 0.60 for the oxygen deficiency δ, in consistency with the Fe{sup 3+}/Fe{sup 4+} ratio derived from the {sup 57}Fe Mössbauer data recorded at both 300 K and 78 K. The Mössbauer data suggests that the Sr{sub 3}Fe{sub 2}O{sub 6.4} nanoparticles are superparamagnetic with blocking temperatures below 78 K. The surfaces of the Sr{sub 3}Fe{sub 2}O{sub 6

Aplicando recomendações da Escala de Braden e prevenindo úlceras por pressão: evidências do cuidar em enfermagem Aplicando las recomendaciones de la Escala de Braden y previniendo las úlceras por presión: evidencias en la atención de enfermería Applying recommendations of the Braden's Scale and preventing pressure ulcers: evidences for nursing care

Directory of Open Access Journals (Sweden)

Cristina Albuquerque de Sousa

2006-06-01

Full Text Available Questiona-se o risco de acometimento de úlcera de pressão (UP no cliente, e a validade do cuidado de enfermagem aplicando a escala de Braden para verificar as evidências desse cuidado na incidência da UP. Utilizou-se o método de medidas biofisiológicas em clientes de UTI. Encontrou-se 11 clientes com UP, numa incidência de 26,83%. A maioria (57,1% de úlcera encontra-se no estágio I. Clientes com UP têm escores menores que os sem UP mostrando sensibilidade para predizer o risco de UP. Concluiu-se que: a evidência dos cuidados de enfermagem foi demonstrada pela densidade de 47,12 % para os clientes sem UP; a incidência das UP foi menor que as encontradas em outras UTIs; os cuidados de enfermagem preventivos reduzem as UP.El riesgo del acometimento de la úlcera por presión en paciente es cuestionable así como la validez de la atención de enfermería al aplicar la escala de Braden para verificar las evidencias de este cuidado y la incidencia de UP. El método de las medidas biofisiológicas en pacientes de UTI fue utilizado. La UP fué encontrada en 11 pacientes en una incidencia de 26.83%. La mayoría (57.1% de las úlceras estavan en el estágio I. Los pacientes con UP tienen scores más bajos que los que no las tenían, demonstrando sensibilidad para predecir lo riesgo para UP. Se ha concluydo que: la evidencia de la atención de enfermería fue demonstrada por la densidad de 47,12% para los pacientes sin UP; la incidencia de la UP fue menor que las encontradas en otras UTIs; la atención preventiva de enfermería reducen las UP.The occurence risk of pressure ulcer (PU by the patient is questioned as well as the validity of nursing care applying the Braden's scale to verify the evidences of this care in the incidence of the PU. The method of biophysiologic measures in ICU patients was used. It was found 11 patients with PU, in a 26,83% incidence. The majority (57,1% of ulcer was in stage I. Patients with PU have lower scores than

Phase quantification of mullite-zirconia and zircon commercial powders using PAC and XRD techniques

Energy Technology Data Exchange (ETDEWEB)

Rendtorff, Nicolas M.; Conconi, Maria S.; Aglietti, Esteban F. [Centro de Tecnologia de Recursos Minerales y Ceramica (CETMIC: CONICET-CIC) (Argentina); Chain, Cecilia Y.; Pasquevich, Alberto F. [Universidad Nacional de La Plata, Departamento de Fisica, IFLP, Facultad de Ciencias Exactas (Argentina); Rivas, Patricia C. [CONICET (Argentina); Martinez, Jorge A., E-mail: toto@fisica.unlp.edu.ar; Caracoche, Maria C. [Universidad Nacional de La Plata, Departamento de Fisica, IFLP, Facultad de Ciencias Exactas (Argentina)

2010-06-15

The short range technique of the Perturbed Angular Correlation (PAC) and x-ray diffraction (Rietveld) methods have been employed to determine the phase content in commercial mullite-zirconia and zircon raw materials that are ordinarily used to produce ceramic materials. The PAC technique, which probes zirconium-containing compounds at nanoscopic level, showed that zircon contains crystalline ZrSiO{sub 4} and an important amount of a structurally distorted zircon, which is also observed accompanying monoclinic zirconia in mullite-zirconia. This particular zircon phase was not detected by the long range x-ray diffraction-Rietveld technique. After an annealing treatment, important changes in crystalline contents of the powders allow confirming, by the x-ray diffraction-Rietveld method, the preexistence of this particular zircon phase. This fact must be taken into account when preparing multicomposites based on the present raw materials.

Sistema Kaizen en la administracion

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Gallegos, H.

2007-01-01

Full Text Available En este artículo presentaremos la importancia que tiene el área de administración como factor de reducción de costos para la empresa aplicando el sistema kaizen. Analizaremos en forma general la administración de las empresas, enfocándonos en las áreas de oportunidad que pueden existir, así como la posible solución a esto, utilizando el sistema kaizen, obteniendo como resultado una reducción de costos, tiempos o mejoras en los procesos administrativos. También se anexa un caso practico en el cual se muestra como aplicando la metodología kaizen en las actividades administrativas podemos lograr una reducción de tiempos y/o costos todo esto causado por la reingeniería de los procesos.

Crystallite Size and Microstrain Measurement of Cathode Material after Mechanical Milling using Neutron Diffraction Technique

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A. Fajar

2010-12-01

Full Text Available The measurements of neutron diffraction patterns of commercially product and 10 hour mechanically milled cathode material lithium cobaltites (LiCoO2 have been performed. Rietveld analysis using FullProf does not show the change of crystal structure due to milling process, but the diffraction pattern has a lower intensity and the diffraction-line was broadening. The results of line-broadening study on milled sample using Rietveld methods detected that the microstrain was occurred in the sample with value 0.127080(35 % and the average crystallite size was 424.78(20 Å.

Aplicación de técnicas de minería de datos a los log generados por CATEDU

OpenAIRE

Buera Corchón, Ricardo

2012-01-01

Extracción de conocimiento de los log generados por un servidor web aplicando técnicas de minería de datos. Extracció de coneixement dels log generats per un servidor web aplicant tècniques de mineria de dades.

Estructura de autocorrelación espacial de la actividad comercial en los municipios de la Región de Murcia.

Directory of Open Access Journals (Sweden)

Juana María Vivo Molina

2004-01-01

Full Text Available En este trabajo, se realiza una aproximación al estudio de la dependencia entre variable económica y localización espacial aplicando la metodología de la Teoría de las Variables Regionalizadas (TVR. En particular, nos centraremos en la localización de actividades económico-comerciales de los municipios de la Comunidad Autónoma de la Región de Murcia (CARM. Aplicando métodos estadísticos para la reducción de datos que nos permiten eliminar información redundante, detectamos estructuras latentes en el desarrollo económico-comercial dentro de los municipios de la CARM. La metodología TVR nos permite constatar la presencia de correlación espacial, considerando los municipios de la Región de Murcia georeferenciados dentro del plano topográfico, en las estructuras latentes detectadas.

Rietveld refinement, impedance spectroscopy and magnetic properties of Bi{sub 0.8}Sr{sub 0.2}FeO{sub 3} substituted Na{sub 0.5}Bi{sub 0.5}TiO{sub 3} ceramics

Energy Technology Data Exchange (ETDEWEB)

Kumari, Rekha [Department of Applied Physics, Guru Jambheshwar University of Science & Technology, Hisar 125001, Haryana (India); Ahlawat, Neetu, E-mail: neetugju@yahoo.co.in [Department of Applied Physics, Guru Jambheshwar University of Science & Technology, Hisar 125001, Haryana (India); Agarwal, Ashish; Sanghi, Sujata [Department of Applied Physics, Guru Jambheshwar University of Science & Technology, Hisar 125001, Haryana (India); Sindhu, Monica [Department of Physics, MKJK College, Rohtak 124001, Haryana (India); Ahlawat, Navneet [Matu Ram Institute of Engineering and Management, Rohtak 124001, Haryana (India)

2016-09-15

We herein presented the investigation on the structural, electrical and magnetic properties of (1−x)(Na{sub 0.5}Bi{sub 0.5}TiO{sub 3})–x(Bi{sub 0.8}Sr{sub 0.2}FeO{sub 3}) polycrystalline ceramic samples, with x=0.1, 0.3, 0.5 and 0.7. These samples were prepared by conventional solid state reaction method and the crystalline phase of prepared ceramics was identified with the help of X-ray diffraction pattern. Rietveld analysis of the obtained XRD data confirmed that all the synthesized samples adopt the rhombohedral crystal structure with R3c space group. Impedance spectroscopic measurements were performed on all the compositions in the frequency range 10 Hz–5 MHz to probe the electrical microstructure of polycrystalline (1−x)(Na{sub 0.5}Bi{sub 0.5}TiO{sub 3})–x(Bi{sub 0.8}Sr{sub 0.2}FeO{sub 3}) ceramics, which changes significantly as a function of x (content of BSFO). A significant increase in dielectric constant has been observed with increase in BSFO concentration, which was attributed to enhancement of oxygen vacancies. Detailed study of impedance complex plane plots revealed the presence of non-Debye type relaxation for all the prepared systems and enabled us to separate the contribution from grains and grain boundaries. Equivalent circuit model (R{sub g}CPE{sub g})(R{sub gb}CPE{sub gb})(R{sub e}CPE{sub e}) was employed to explain the impedance data for all the prepared samples. The activation energies obtained from electric modulus as well as dc conductivity increase with increase in BSFO content, which approaches the value 1 eV and indicates an Arrehenius type thermally activated process. Remnant magnetization (M{sub r}) and coercive field (H{sub c}) are found to be increase with BSFO concentration. - Highlights: • (1−x)NBT–xBSFO (x=0.1, 0.3, 0.5, 0.7) ceramics were prepared. • There is no change in crystal structure. • These can be used as data storage materials.

Structural refinement, photoluminescence and Raman spectroscopy of wurtzite Mn-doped Zn O pellets

Energy Technology Data Exchange (ETDEWEB)

Marquina, J.; Martin, J.; Luengo, J.; Vera, F.; Roa, L. [Centro de Estudios Avanzados en Optica, Universidad de los Andes, Merida 5101 (Venezuela, Bolivarian Republic of); Gonzalez, J. [Centro de Estudios de Semiconductores, Universidad de los Andes, Merida 5101 (Venezuela, Bolivarian Republic of); Rodriguez, F.; Renero L, C.; Valiente, R. [Malta-Consolider Team, CITIMAC, Facultad de Ciencias, Universidad de Cantabria, Santander 69005 (Spain); Delgado, G. E., E-mail: marquinajesus@gmail.com [Laboratorio de Cristalografia, Facultad de Ciencias, Universidad de los Andes, Merida 5101 (Venezuela, Bolivarian Republic of)

2017-11-01

We report the results of the Rietveld refinement, photoluminescence and Raman spectroscopy of Mn-doped Zn O ceramic pellets. Rietveld refinement shows that samples crystallize in the wurtzite structure and for the Mn-doped sample indicated that the Mn atoms substitute the Zn tetrahedral crystallographic sites in the Zn O host lattice. The emission and absorption spectra of Mn-doped Zn O have been investigated in the visible-UV region and the data have been interpreted in terms of the wurtzite Zn O electronic structure. Two broad bands, one due to superposition between donor bound excitons (DX) and free excitons (FX) and other due free-to bond excitonic recombination (FB) dominates the low-temperature photoluminescence spectra of Mn-doped Zn O bulk. In the Raman spectrum, an extra mode at ∼520 cm{sup -1} has been observed in agreement with earlier works, and it is an indicator for the incorporation of Mn{sup +2} ions into the Zn O host matrix since it is not is observed in Zn O pristine. Rietveld refinement of the X-ray diffraction patterns, energy-dispersive X-ray spectroscopy (EDS) technique, and Raman spectroscopies were performed to study these effects. (Author)

Grain size dependent phase stabilities and presence of a monoclinic (Pm) phase in the MPB region of (1-x)Bi(Mg_1_/_2Ti_1_/_2)O_3_-_xPbTiO_3

International Nuclear Information System (INIS)

Upadhyay, A.; Singh, A.K.

2016-01-01

The results of the room temperature structural studies on (1-x)Bi(Mg_1_/_2Ti_1_/_2)O_3_-_xPbTiO_3 ceramics using Rietveld analysis of the powder X-ray diffraction data in the composition range 0.28≤x≤0.45 are presented. The morphotropic phase boundary region exhibits coexistence of monoclinic (space group Pm) and tetragonal (space group P4mm) phases in the composition range 0.33≤x≤0.40. The structure is nearly single phase monoclinic (space group Pm) in the composition range 0.28≤x≤0.32. The structure for the compositions with x≥0.45 is found to be predominantly tetragonal with space group P4mm. Rietveld refinement of the structure rules out the coexistence of rhombohedral and tetragonal phases in the morphotropic phase boundary region reported by earlier authors. The Rietveld structure analysis for the sample x=0.35 calcined at various temperatures reveals that phase fraction of the coexisting phases in the morphotropic phase boundary region varies with grain size. The structural parameters of the two coexisting phases also change slightly with changing grain size. (author)

El marketing político

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Alvaro H. Cifuentes G.

2015-04-01

Full Text Available RESUMEN Si un candidato desea ser elegido, las técnicas de marketing aplicadas a la política, le son imprescindibles. El marketing político (Politing es el análisis  metódico de los diferentes segmentos que integran el ámbito político de una sociedad y de los factores que puedan modificarlos. Se aplican al candidato, a los votantes, al análisis de la publicidad política, a los simpatizantes, a desconocedores  del partido y a los indecisos. Los candidatos colombianos lo están aplicando, y compañías nuestras exportan servicios  de asesoría de países suramericanos.Promocionar  un candidato implica estructurar una compañía tal como una empresa, aplicando técnicas de ventas, de fijación de cuotas y de planeación estratégica.

Tin-Platinum catalysts interactions on titania and silica

International Nuclear Information System (INIS)

Nava, N.; Del Angel, P.; Salmones, J.; Baggio-Saitovitch, E.; Santiago, P.

2007-01-01

Pt-Sn was supported on titania and silica, and the resulting interactions between the components in prepared samples and the resulting interactions between the components before and after treatment with hydrogen were characterized by Moessbauer spectroscopy, X-ray diffraction, Rietveld refinement, high-resolution transmission electron microscopy (HRTEM) and catalytic tests data. Results show the presence of Pt and SnO 2 after calcinations, and Pt 3 Sn, PtSn and PtSn 3 after reduction. Rietveld analysis shows that some Ti 4+ are replaced by Sn 4+ atoms in the titania structure. Finally, HRTEM and the practically absence of activity observed confirms that metallic platinum is encapsulated

Implementación del proceso de canal verde en la aduana marítima de Guayaquil

OpenAIRE

Celi Chamba, Johanna Paola

2008-01-01

propone un nuevo proceso para facilitar el comercio exterior y de manera en especial las actividades de importación; este proceso denominado Canal Verde o Aforo Automático está siendo aplicando en la mayoría de las aduanas del mundo logrando crear aduanas eficientes

El deporte y la podología: tendencias actuales en ortopodología (primera parte)

OpenAIRE

Dorca Coll, Adelina; Céspedes Céspedes, Tomás; Cuevas Gómez, Rafael; Sacristán Valero, Sergi

1993-01-01

Se pretende revisar los conceptos y criterios que se venían aplicando en ortopodología y exponer las tendencias actuales tanto en la valoración de los parámetros previos al diseño ortopodológico como en la confección del tratamiento.

Analysis of the zirconia structure by `ab initio` and Rietveld methods; Analise da estrutura da zirconia por metodos `Ab initio` e de Rietveld

Energy Technology Data Exchange (ETDEWEB)

Bechepeche, A.P.; Nasar, R.S.; Longo, E. [Sao Carlos Univ., SP (Brazil). Dept. de Quimica; Treu Junior, O.; Varela, J.A. [UNESP, Araraquara, SP (Brazil). Inst. de Quimica

1995-12-31

The zirconia was doped with 0,113 mol of Mg O e 0,005 mol of Ti O{sub 2}, and it was calcined in 1550{sup d}eg C and it was analyzed by XRD. The results shows that pure zirconia contains 96,19% of monoclinic phase and 3,18% of cubic. However, the doping magnesia stabilizes the zirconia in 17,24 of monoclinic; 29,63 of tetragonal and 53,13% of cubic phase. The addition of titanium in zirconia gives 25,85% of tetragonal phase and 37,66% of cubic, and this shows the no stabilizing action of this transition metal. By the other side, the results with ab-initio calculating shows the same tendency resulting in the next values of total energy: pure zirconia - monoclinic -11.316,86ua; tetragonal -8742,09 ua and cubic -8742,80 ua and Zr O{sub 2} Ti O{sub 2} system - monoclinic -9463,02 ua, tetragonal -9459,39 ua and cubic -9459,97 ua (author) 3 figs., 2 tabs.

Correlação entre dados estruturais e bandas de vibração no infravermelho para a fase espinélio Zn7-xNi xSb2O12 Correlation between structural data and infraved vibrational bands of the Zn7-xNi xSb2O12 spinel phase

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L. Gama

2000-12-01

Full Text Available A fase espinélio Zn7-xNi xSb2O12 tem apresentado propriedades magnéticas importantes, comportando-se como spin-glass. Desde que estas propriedades são fortemente dependentes da configuração precisa dos átomos nesta estrutura, foram utilizados neste trabalho, com o intuito de clarificar essa configuração, a espectroscopia de infravermelho, aliada ao refinamento de estruturas pelo método de Rietveld. O espectro de infravermelho mostra nas condições de contorno estudadas a presença de três das quatro bandas ativas comuns aos espinélios. Conforme resultados do refinamento pelo método de Rietveld, o níquel substitui o zinco primeiramente no sítio octaédrico e, em altas concentrações (x > ou = 3, migra para o sítio tetraédrico. Essa migração é indicada pelo "splitting", em torno de 520 cm-1, para (x > ou = 3, apresentado no espectro de infravermelho quando a banda n2 é afetada pela mudança do cátion bivalente.The Zn7-xNi xSb2O12 spinel phase shows important magnetic properties with a spin-glass behavior. As these properties are strongly dependent on the atomic configuration in the spinel structure, infrared spectroscopy and the structure refining by the Rietveld analysis have been studied. The infrared spectrum presents three to four of the common spinel active modes. The Rietveld analysis shows that Ni firstly substitutes for Zn in the octahedral site and, for large (x > or = 3 concentrations, migrates to the tetrahedral site. The indication of that migration is the splitting at approximately 520 cm-1, shown in the infrared spectrum when the nu 2 band is modified by the substitution of the divalent cation.

Transformation of Goethite to Hematite Nanocrystallines by High Energy Ball Milling

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O. M. Lemine

2014-01-01

Full Text Available α-Fe2O3 nanocrystallines were prepared by direct transformation via high energy ball milling treatment for α-FeOOH powder. X-ray diffraction, Rietveld analysis, TEM, and vibrating sample magnetometer (VSM are used to characterize the samples obtained after several milling times. Phase identification using Rietveld analysis showed that the goethite is transformed to hematite nanocrystalline after 40 hours of milling. HRTEM confirm that the obtained phase is mostly a single-crystal structure. This result suggested that the mechanochemical reaction is an efficient way to prepare some iron oxides nanocrystallines from raw materials which are abundant in the nature. The mechanism of the formation of hematite is discussed in text.

Tin-Platinum catalysts interactions on titania and silica

Energy Technology Data Exchange (ETDEWEB)

Nava, N. [Instituto Mexicano del Petroleo Lazaro Cardenas 152, 07730 Mexico, D.F. (Mexico)], E-mail: tnava@imp.mx; Del Angel, P. [Instituto Mexicano del Petroleo Lazaro Cardenas 152, 07730 Mexico, D.F. (Mexico); Salmones, J. [Instituto Politecnico Nacional-ESIQIE UPALM, 07738 Mexico, D.F. (Mexico); Baggio-Saitovitch, E. [Centro Brasileiro de Pesquisas Fisicas, Rua Dr. Xavier Sigaud 150, 22290-180 Rio de Janeiro, Brasil (Brazil); Santiago, P. [Instituto de Fisica, UNAM, Mexico, D. F., 04510 Mexico (Mexico)

2007-09-30

Pt-Sn was supported on titania and silica, and the resulting interactions between the components in prepared samples and the resulting interactions between the components before and after treatment with hydrogen were characterized by Moessbauer spectroscopy, X-ray diffraction, Rietveld refinement, high-resolution transmission electron microscopy (HRTEM) and catalytic tests data. Results show the presence of Pt and SnO{sub 2} after calcinations, and Pt{sub 3}Sn, PtSn and PtSn{sub 3} after reduction. Rietveld analysis shows that some Ti{sup 4+} are replaced by Sn{sup 4+} atoms in the titania structure. Finally, HRTEM and the practically absence of activity observed confirms that metallic platinum is encapsulated.

Local and average structures of 0.7Pb(Mg1/3Nb2/3)O3 - 0.3PbZrO3

International Nuclear Information System (INIS)

Krishna, P.S.R.; Shinde, A.B.; Narasimhan, S.L.; Tiwari, V.S.; Singh, G.

2005-01-01

The local and average structure of 0.7Pb(Mg 1/3 Nb 2/3 )O 3 - 0.3PbZrO 3 (PMN-PZ) was studied by neutron diffraction. The Rietveld refinement was carried out to determine the average, long-range crystallographic structure, while the pair density function (PDF) analysis was used in studying the local atomic structure. The local atomic structure determined by the PDF analysis, was found to be significantly different from the average crystallographic structure determined by the Rietveld analysis. These results show that the conflict between the local structural preference and the average structure is not limited to relax or ferroelectric oxides, but may be widely prevalent in mixed-ion ferroelectrics. (author)

Grain size dependent phase stabilities and presence of a monoclinic (Pm) phase in the morphotropic phase boundary region of (1−x)Bi(Mg{sub 1/2}Ti{sub 1/2})O{sub 3}-xPbTiO{sub 3} piezoceramics

Energy Technology Data Exchange (ETDEWEB)

Upadhyay, Ashutosh; Singh, Akhilesh Kumar, E-mail: akhilesh-bhu@yahoo.com, E-mail: aksingh.mst@itbhu.ac.in [School of Materials Science and Technology, Indian Institute of Technology (Banaras Hindu University), Varanasi 221005 (India)

2015-04-14

Results of the room temperature structural studies on (1−x)Bi(Mg{sub 1/2}Ti{sub 1/2})O{sub 3}-xPbTiO{sub 3} ceramics using Rietveld analysis of the powder x-ray diffraction data in the composition range 0.28 ≤ x ≤ 0.45 are presented. The morphotropic phase boundary region exhibits coexistence of monoclinic (space group Pm) and tetragonal (space group P4 mm) phases in the composition range 0.33 ≤ x ≤ 0.40. The structure is nearly single phase monoclinic (space group Pm) in the composition range 0.28 ≤ x ≤ 0.32. The structure for the compositions with x ≥ 0.45 is found to be predominantly tetragonal with space group P4 mm. Rietveld refinement of the structure rules out the coexistence of rhombohedral and tetragonal phases in the morphotropic phase boundary region reported by earlier authors. The Rietveld structure analysis for the sample x = .35 calcined at various temperatures reveals that phase fraction of the coexisting phases in the morphotropic phase boundary region varies with grain size. The structural parameters of the two coexisting phases also change slightly with changing grain size.

Vulnerabilidad y riesgo por inundación en San Cristóbal de las Casas, Chiapas

Directory of Open Access Journals (Sweden)

Guillermo Montoya Gómez

2008-01-01

en las colonias localizadas en los márgenes de los ríos utilizando un modelo digital de elevación y aplicando encuestas. Se determinaron las características de las viviendas, el nivel de ingresos de sus pobladores y los grados de vulnerabilidad y riesgo a que están expuestos.

Žena jako tvůrkyně

Czech Academy of Sciences Publication Activity Database

Hnídková, Vendula

2012-01-01

Roč. 91, č. 9 (2012), s. 542-544 ISSN 0042-4544 Institutional support: RVO:68378033 Keywords : Dutch architecture * modern architecture * Gerrit Rietveld Subject RIV: AL - Art, Architecture, Cultural Heritage

High-pressure studies of a ThMn sub 1 sub 2 -type actinide compound: UFe sub 5 Al sub 7

CERN Document Server

Halevy, I; Kimmel, G; Atzmony, U; Pereira, L C J; Goncalves, A P; Schäfer, W

2002-01-01

The ternary inter-metallic compound, UFe sub 5 Al sub 7 , crystallize in a tetragonal ThMn sub 1 sub 2 type structure. In the as-cast samples a residual phase of FeAl (approx 2% wt) was identified in the grain boundaries. The amount of the residual cubic phase of FeAl was determined by Rietveld analysis and reduced by the annealing process. UFe sub 5 Al sub 7 maintains the tetragonal symmetry as a function of pressure, while FeAl keeps the cubic structure as was determined by the Rietveld analysis. The volume-pressure curve calculated from the x-ray analysis is V/V sub 0 = 0.87 for UFe sub 5 Al sub 7 at 26.0 GPa.

Temperature-Induced Desorption of Methyl tert-Butyl Ether Confined on ZSM-5: An In Situ Synchrotron XRD Powder Diffraction Study

Directory of Open Access Journals (Sweden)

Elisa Rodeghero

2017-02-01

Full Text Available The temperature-induced desorption of methyl tert-butyl ether (MTBE from aqueous solutions onto hydrophobic ZSM-5 was studied by in situ synchrotron powder diffraction and chromatographic techniques. This kind of information is crucial for designing and optimizing the regeneration treatment of such zeolite. The evolution of the structural features monitored by full profile Rietveld refinements revealed that a monoclinic (P21/n to orthorhombic (Pnma phase transition occurred at about 100 °C. The MTBE desorption process caused a remarkable change in the unit-cell parameters. Complete MTBE desorption was achieved upon heating at about 250 °C. Rietveld analysis demonstrated that the desorption process occurred without any significant zeolite crystallinity loss, but with slight deformations in the channel apertures.

Synthesis, magnetic properties and Moessbauer spectroscopy for the pyrochlore family Bi{sub 2}BB Prime O{sub 7} with B=Cr and Fe and B Prime =Nb, Ta and Sb

Energy Technology Data Exchange (ETDEWEB)

Blanco, Maria C. [INFIQC (CONICET), Dpto. de Fisicoquimica, Fac. de Ciencias Quimicas, U.N.C., Cordoba (X5000HUA) (Argentina); Franco, Diego G. [INFIQC (CONICET), Dpto. de Fisicoquimica, Fac. de Ciencias Quimicas, U.N.C., Cordoba (X5000HUA) (Argentina); Centro Atomico Bariloche - CNEA, Av. E. Bustillo 9500, S.C. de Bariloche (8500), R.N. (Argentina); Jalit, Yamile; Pannunzio Miner, Elisa V. [INFIQC (CONICET), Dpto. de Fisicoquimica, Fac. de Ciencias Quimicas, U.N.C., Cordoba (X5000HUA) (Argentina); Berndt, Graciele; Paesano, Andrea [Departamento de Fisica, Universidade Estadual de Maringa, Parana (Brazil); Nieva, Gladys [Centro Atomico Bariloche - CNEA, Av. E. Bustillo 9500, S.C. de Bariloche (8500), R.N. (Argentina); Carbonio, Raul E., E-mail: carbonio@mail.fcq.unc.edu.ar [INFIQC (CONICET), Dpto. de Fisicoquimica, Fac. de Ciencias Quimicas, U.N.C., Cordoba (X5000HUA) (Argentina)

2012-08-15

The samples Bi{sub 2}BB Prime O{sub 7}, with B=Cr and Fe and B Prime =Nb, Ta and Sb were prepared by solid state method. The crystallographic structure was investigated on the basis of X-ray powder diffraction data. Rietveld refinements show that the crystal structure is cubic, space group Fd-3m. The Bi{sup 3+} cation on the eight-coordinate pyrochlore A-site shows displacive disorder, as a consequence of its lone pair electron configuration. There is also a considerable A-site disorder shown by Rietveld Analysis and confirmed in the case of the iron containing samples with Moessbauer spectroscopy. The magnetic measurements show paramagnetic behavior at all temperatures for the Cr oxides. The Fe pyrochlores show antiferromagnetic order around 10 K.

X-ray and electron diffraction studies of the structures of pseudo-perovskite compounds Pb2(Sc,Ta)O6 and Pb2(Mg,W)O6

International Nuclear Information System (INIS)

Baba-Kishi, K.Z.; Cernik, R.J.

1992-01-01

Electron diffraction patterns, X-ray precession patterns and synchrotron Rietveld powder diffraction profiles were used to study the crystal structure of the pseudo-perovskite compound Pb 2 (Sc, Ta)O 6 (PST). The results of a Rietveld refinement and single-crystal X-ray precession studies showed that PST has a lower symmetry than the cubic Fm3m in the paraelectric state. The remarkable similarities between the crystal structures of the antiferroelectric Pb 2 (Mg, W)O 6 (PMW) and ferroelectric PST are studied in detail by electron diffraction and it is suggested that PST is a weak or frustrated antiferroelectric oxide. The influence of the degree of structural long-range order on the existence of an antiferroelectric phase transition in PST and PMW is discussed. (orig.)

On the use of a composite moderator at the IBR-2 reactor: Advantages for the neutron-diffraction texture analysis of rocks

Czech Academy of Sciences Publication Activity Database

Bulavin, M. V.; Vasin, R.N.; Kulikov, S.A.; Lokajíček, Tomáš; Levin, D.M.

2016-01-01

Roč. 10, č. 4 (2016), s. 677-686 ISSN 1027-4510 Institutional support: RVO:67985831 Keywords : cold moderator * neutron-diffraction texture analysis * phase analysis * Rietveld method Subject RIV: DB - Geology ; Mineralogy

Rietveld analysis, dielectric and impedance behaviour of Mn /Fe ion ...

Indian Academy of Sciences (India)

Figure 1 compares X-ray diffraction patterns of pow- ders calcined at temperature .... ground, absorption coefficient, atomic positions, two theta zero error, thermal ... attributed to segregation of Mn and Fe at grain boundaries. (Dai et al 1995).

Structure of Pigment Yellow 181 dimethylsulfoxide N-methyl-2-pyrrolidone (1:1:1) solvate from XRPD + DFT-D

International Nuclear Information System (INIS)

Streek, Jacco van de

2015-01-01

The relatively complex structure of a triclinic disolvate was solved from low-resolution laboratory powder diffraction data through the intermediate use of dummy atoms and the combination with quantum-mechanical calculations. With only a 2.6 Å resolution laboratory powder diffraction pattern of the θ phase of Pigment Yellow 181 (P.Y. 181) available, crystal-structure solution and Rietveld refinement proved challenging; especially when the crystal structure was shown to be a triclinic dimethylsulfoxide N-methyl-2-pyrrolidone (1:1:1) solvate. The crystal structure, which in principle has 28 possible degrees of freedom, was determined in three stages by a combination of simulated annealing, partial Rietveld refinement with dummy atoms replacing the solvent molecules and further simulated annealing. The θ phase not being of commercial interest, additional experiments were not economically feasible and additional dispersion-corrected density functional theory (DFT-D) calculations were employed to confirm the correctness of the crystal structure. After the correctness of the structure had been ascertained, the bond lengths and valence angles from the DFT-D minimized crystal structure were fed back into the Rietveld refinement as geometrical restraints (‘polymorph-dependent restraints’) to further improve the details of the crystal structure; the positions of the H atoms were also taken from the DFT-D calculations. The final crystal structure is a layered structure with an elaborate network of hydrogen bonds

Layered B-site cation ordering: A key factor in ferrimagnetism of Y{sub 2}MnCrO{sub 6}

Energy Technology Data Exchange (ETDEWEB)

Hao, Lin [Department of Physics, University of Science and Technology of China, Hefei, Anhui (China); Yang, Lei [Collaborative Innovation Center for Magnetoelectric Industry, China Three Gorges University, Yichang, Hubei (China); Lee, Ming-Hsien; Lin, Tseh-Hsing [Department of Physics, Tamkang University, Taipei, Taiwan (China); Zhang, ZhongFeng; Xie, XiangNan [Department of Physics, University of Science and Technology of China, Hefei, Anhui (China); Zhu, Hong, E-mail: zhuh@ustc.edu.cn [Department of Physics, University of Science and Technology of China, Hefei, Anhui (China)

2014-07-15

Highlights: • Rietveld refinement and first-principles calculations are performed for Y{sub 2}MnCrO{sub 6}. • The layered B-site cation ordering is a more reliable structure for Y{sub 2}MnCrO{sub 6}. • Y{sub 2}MnCrO{sub 6} has an insulating ferrimagnetism (0 0 1)-ordered ground state. • The layered ordered pattern plays a key role for the ferrimagnetism in Y{sub 2}MnCrO{sub 6}. - Abstract: We report the Rietveld refinement of powder X-ray diffraction (XRD) pattern and first-principles calculations for the half-Cr{sup 3+} doped YMnO{sub 3} compound. The Rietveld refinement results suggest that the compound has a monoclinic structure with the Mn{sup 3+}/Cr{sup 3+} layers alternately stacking along the [0 0 1] direction. The first-principles calculations show that the structure with layered B-site cation ordering has the lowest total energy; meanwhile, the insulating ferrimagnetic state is more favored compared to the ferromagnetic state, which is in agreement with the reported experimental results. Based upon Goodenough’s model of semi-covalent exchange, we argue that the anisotropic magnetic couplings between the Mn{sup 3+}/Cr{sup 3+} cations ordered in layered pattern play an important role for the ferrimagnetism in the compound.

Analysis and interpretation of diffraction data from complex, anisotropic materials

Science.gov (United States)

Tutuncu, Goknur

Most materials are elastically anisotropic and exhibit additional anisotropy beyond elastic deformation. For instance, in ferroelectric materials the main inelastic deformation mode is via domains, which are highly anisotropic crystallographic features. To quantify this anisotropy of ferroelectrics, advanced X-ray and neutron diffraction methods were employed. Extensive sets of data were collected from tetragonal BaTiO3, PZT and other ferroelectric ceramics. Data analysis was challenging due to the complex constitutive behavior of these materials. To quantify the elastic strain and texture evolution in ferroelectrics under loading, a number of data analysis techniques such as the single peak and Rietveld methods were used and their advantages and disadvantages compared. It was observed that the single peak analysis fails at low peak intensities especially after domain switching while the Rietveld method does not account for lattice strain anisotropy although it overcomes the low intensity problem via whole pattern analysis. To better account for strain anisotropy the constant stress (Reuss) approximation was employed within the Rietveld method and new formulations to estimate lattice strain were proposed. Along the way, new approaches for handling highly anisotropic lattice strain data were also developed and applied. All of the ceramics studied exhibited significant changes in their crystallographic texture after loading indicating non-180° domain switching. For a full interpretation of domain switching the spherical harmonics method was employed in Rietveld. A procedure for simultaneous refinement of multiple data sets was established for a complete texture analysis. To further interpret diffraction data, a solid mechanics model based on the self-consistent approach was used in calculating lattice strain and texture evolution during the loading of a polycrystalline ferroelectric. The model estimates both the macroscopic average response of a specimen and its hkl

Accurate quantitative XRD phase analysis of cement clinkers

International Nuclear Information System (INIS)

Kern, A.

2002-01-01

Full text: Knowledge about the absolute phase abundance in cement clinkers is a requirement for both, research and quality control. Traditionally, quantitative analysis of cement clinkers has been carried out by theoretical normative calculation from chemical analysis using the so-called Bogue method or by optical microscopy. Therefore chemical analysis, mostly performed by X-ray fluorescence (XRF), forms the basis of cement plan control by providing information for proportioning raw materials, adjusting kiln and burning conditions, as well as cement mill feed proportioning. In addition, XRF is of highest importance with respect to the environmentally relevant control of waste recovery raw materials and alternative fuels, as well as filters, plants and sewage. However, the performance of clinkers and cements is governed by the mineralogy and not the elemental composition, and the deficiencies and inherent errors of Bogue as well as microscopic point counting are well known. With XRD and Rietveld analysis a full quantitative analysis of cement clinkers can be performed providing detailed mineralogical information about the product. Until recently several disadvantages prevented the frequent application of the Rietveld method in the cement industry. As the measurement of a full pattern is required, extended measurement times made an integration of this method into existing automation environments difficult. In addition, several drawbacks of existing Rietveld software such as complexity, low performance and severe numerical instability were prohibitive for automated use. The latest developments of on-line instrumentation, as well as dedicated Rietveld software for quantitative phase analysis (TOPAS), now make a decisive breakthrough possible. TOPAS not only allows the analysis of extremely complex phase mixtures in the shortest time possible, but also a fully automated online phase analysis for production control and quality management, free of any human interaction

The study of disorder and nanocrystallinity in C–S–H, supplementary cementitious materials and geopolymers using pair distribution function analysis

KAUST Repository

Meral, Cagla; Benmore, C.J.; Monteiro, Paulo J.M.

2011-01-01

Significant progress was achieved with the application of Rietveld method to characterize the crystalline phases in portland cement paste. However, to obtain detailed information on the amorphous or poorly crystalline phases, it is necessary

Expanding the structural landscape of niclosamide: a high Z ' polymorph, two new solvates and monohydrate H_A

DEFF Research Database (Denmark)

Sovago, Ioana; Bond, Andrew D.

2015-01-01

to be twinned by twofold rotation around that axis. The acetonitrile molecules occupy channels in the structure. A complete structure is provided for niclosamide monohydrate, C13H8Cl2N2O4·H2O, polymorph HA, obtained by Rietveld refinement against laboratory powder X-ray diffraction data. It has been suggested...... that this compound is related to the methanol solvate of niclosamide [Harriss, Wilson & Radosevljevic Evans (2014). Acta Cryst. C70, 758-763], but it is found that the two are not fully isostructural: they contain isostructural two-dimensional layers, but the layers are arranged differently in the two structures....... This suggests that HA may have the potential for polytypism, and features in the Rietveld difference curve indicate that a polytype fully isostructural with the methanol solvate might be present....

In Situ High Resolution Synchrotron X-Ray Powder Diffraction Studies of Lithium Batteries

DEFF Research Database (Denmark)

Amri, Mahrez; Fitch, Andy; Norby, Poul

2015-01-01

allowing diffraction information to be obtained from only the active material during battery operation [2]. High resolution synchrotron x-ray powder diffraction technique has been undertaken to obtain detailed structural and compositional information during lithiation/delithiation of commercial LiFePO4...... materials [3]. We report results from the first in situ time resolved high resolution powder diffraction experiments at beamline ID22/31 at the European Synchrotron Radiation Facility, ESRF. We follow the structural changes during charge of commercial LiFePO4 based battery materials using the Rietveld...... method. Conscientious Rietveld analysis shows slight but continuous deviation of lattice parameters from those of the fully stoichiometric end members LiFePO4 and FePO4 indicating a subsequent variation of stoichiometry during cathode delithiation. The application of an intermittent current pulses during...

Effect of titania on the characteristics of a Tin-Platinum catalyst

Energy Technology Data Exchange (ETDEWEB)

Morales-Gil, P., E-mail: moralesp@imp.mx; Nava, N. [Instituto Mexicano del Petróleo (Mexico); Baggio-Saitovitch, E. [Centro Brasileiro de Pesquisas Físicas (Brazil)

2015-06-15

Pt-Sn bimetallic catalysts dispersed on alumina are commonly used for reforming and dehydrogenation reactions. In this research work, Pt and Sn were supported on titania. The resulting interactions between the components in the prepared samples, before and after treatment with hydrogen, were studied by Mössbauer spectroscopy, X-ray diffraction and Rietveld refinement. The results show the presence of Pt and SnO{sub 2} after calcinations. After the reduction process, metallic Pt, PtSn, and Pt{sub 3}Sn alloys were identified. The Rietveld refinement analysis shows that some Ti{sup 4+} atoms were replaced by Sn{sup 4+} atoms in the titania structure. Finally, the Mössbauer spectroscopy and X-ray diffraction results indicate that metallic platinum and SnO{sub 2} are encapsulated by a TiOx layer.

Microstructural studies on variation of defect parameters in Zr–Sn

Indian Academy of Sciences (India)

... modified Rietveld method and Warren–Averbach method taking silicon as standard. ... This analysis confirms that the growth fault, , is totally absent or negligibly ... faulting tendency abruptly drops to a level of negligible presence or zero.

Preferred orientation of ettringite in concrete fractures

KAUST Repository

Wenk, Hans-Rudolf; Monteiro, Paulo J. M.; Kunz, Martin; Chen, Kai; Tamura, Nobumichi; Lutterotti, Luca; Del Arroz, John

2009-01-01

distribution of ettringite crystals. Diffraction images are analyzed using the Rietveld method to obtain information on textures. The analysis reveals that the c axes of the trigonal crystallites are preferentially oriented perpendicular to the fracture

Effect of an electrolyte flow on electrochemical hydrogen permeation

Directory of Open Access Journals (Sweden)

Ana María Pérez-Ceballos

2014-01-01

Full Text Available Se ha estudiado el efecto de la aplicación de un flujo de elect rolito sobre la superficie de detección de una membrana de hier ro puro en ensayos de permeación electroquímica de hidrógeno. Para la real ización de los ensayos se usó una celda del tipo Devanathan mod ificada, de tal manera que un flujo de electrolito fue inyectado directa mente sobre la superficie de salida de hidrógeno. La generación de hidrógeno se realizó aplicando una corriente catódica de 2,85mA y se usó una solución de NaOH 0,1M + 2mgL-1 As2O3. La celda de detección fue mantenida bajo control potenciostático y se usó u na solución buffer de borato de sodio (pH=8,4. No se observó u na variación significativa de la corriente de permeación en los en sayos realizados aplicando flujo de electrolito.

Kunst voorbij identiteit en differentiatie

NARCIS (Netherlands)

F.D.R. Maet (Frank)

2005-01-01

textabstractFrank Maet heeft opleidingen gevolgd in theater (Kleine Academie Brussel) en beeldende kunst (Rietveld Academie Amsterdam) en vervolgens filosofie gestudeerd (V.U.Brussel). Zijn eindverhandeling zocht naar invloeden van de esthetica op de wetenschapsfilosofie (met voornamelijk aandacht

Eficacia de la acupuntura en la espasticidad del paciente que ha padecido un ictus. Revisión sistemática

Directory of Open Access Journals (Sweden)

Juan Rodríguez-Mansilla

2016-04-01

Conclusión: Aunque se muestran mejoras respecto a la reducción de la espasticidad, la eficacia de la técnica no ha podido demostrarse para esta enfermedad. Son necesarios estudios que calculen el tamaño de los efectos reportados, aplicando procedimientos homogéneos en el diseño así como en la duración, frecuencia e instrumentos de medida utilizados.

Plan de mercadeo para una promotora de eventos corporativos

OpenAIRE

Burbano Zhindon, Andrea Cristina; Chavez Lopez, Maria Cecilia; Orlando Haro, Sofia Pierina; Miranda, Jorge Luis

2009-01-01

Este proyecto presenta una alternativa para todas aquellas empresas que realizan eventos frecuentemente, ofreciéndoles un servicio personalizado para la coordinación de cada uno de los detalles que conlleva la organización de un evento. El objetivo fundamental de este estudio es desarrollar un plan de mercadeo para el servicio antes mencionado, aplicando los principios del marketing para su correcta implementación.

Applicability of empirical correlations for estimating global solar radiation

International Nuclear Information System (INIS)

Gopinathan, K.K.; Baholo, M.

1987-01-01

Three empirical models suggested by different investigators, for estimating monthly mean daily global radiation on a horizontal surface, are compared statistically to test their universal applicability. The models thus compared are those suggested by Rietveld, Glover and McCulloch and Gopinathan. The models are compared by calculating the root mean square error, mean bias error and mean relative percentage error values. The model suggested by Gopinathan yields the best results in terms of root mean square, mean bias and mean percentage errors. The model by Rietveld is the second best and the model by Glover and McCulloch comes at third place. However, the differences in the magnitude of errors among the three models are very small and all the three models can be considered to be accurate for global radiation estimation for any location in the world

Synthesis and crystal structure of the quaternary compound AgFe{sub 2}GaTe{sub 4}

Energy Technology Data Exchange (ETDEWEB)

Delgado, Gerzon E., E-mail: gerzon@ula.ve [Laboratorio de Cristalografía, Departamento de Química, Facultad de Ciencias, Universidad de Los Andes, Mérida 5101 (Venezuela, Bolivarian Republic of); Quintero, Eugenio; Tovar, Rafael; Grima-Gallardo, Pedro; Quintero, Miguel [Centro de Estudio de Semiconductores, Departamento de Física, Facultad de Ciencias, Universidad de Los Andes, Mérida 5101 (Venezuela, Bolivarian Republic of)

2014-11-15

Highlights: • New quaternary compound. • Synthesis from solid state reaction. • Crystal structure. • Rietveld refinement. - Abstract: The crystal structure of the quaternary compound AgFe{sub 2}GaTe{sub 4}, belonging to the system I–II{sub 2}–III–VI{sub 4}, was characterized by Rietveld refinement using X-ray powder diffraction data. The powder pattern was composed by 84.5% of the principal phase AgFe{sub 2}GaTe{sub 4} and 15.5% of the secondary phase FeTe. This material crystallizes with stannite structure in the tetragonal space group I-42m (N° 121), Z = 2, unit cell parameters a = 6.3409(2) Å, c = 12.0233(4) Å, V = 483.42(3) Å{sup 3}, and is isostructural with CuFe{sub 2}InSe{sub 4}.

Applying the X-ray diffraction analysis for estimating the height and width of nanorods in low symmetry crystal multiphase materials

Science.gov (United States)

Mokhtari, Ali; Soleimanian, Vishtasb; Dehkordi, Hamed Aleebrahim; Dastafkan, Kamran

2017-11-01

In this work the potential of Rietveld refinement procedure is used to study the shape and size of non-spherical nanocrystallites. The main advantages of this approach are that not only it can successfully extend to all nanomaterials with different crystal symmetries but also it can evaluate the various phases of multiple materials comparing to electron microscopy methods. Therefore, between seven crystal systems, the formulation of monoclinic and hexagonal crystals is developed. This procedure is applied for the mixture of sodium carbonate and zinc oxide nanocrystallites at different fractions of doped gadolinium oxide. It is found that the crystallites of sodium carbonate and zinc oxide have the rod and ellipsoidal shapes, respectively. The microstructure results are compared with the results of scanning electron microscopy imaging. Good agreement is achieved between the results of scanning electron microscopy and Rietveld methods.

Neutron diffraction studies on Ca1− xBaxZr4P6O24 solid solutions

Indian Academy of Sciences (India)

P6O24 compositions from combined Rietveld refinements of powder X-ray and neutron diffraction data. All the studied compositions crystallize in rhombohedral lattice (space group R-3 No. 148). A continuous solid solution is concluded from ...

Minimization of absorption contrast for accurate amorphous phase quantification: application to ZrO.sub.2./sub. nanoparticles

Czech Academy of Sciences Publication Activity Database

Suzuki-Muresan, T.; Deniard, P.; Gautron, E.; Petříček, Václav; Jobic, S.; Grambow, B.

2010-01-01

Roč. 43, Part 5 (2010), 1092-1099 ISSN 0021-8898 Institutional research plan: CEZ:AV0Z10100521 Keywords : x-ray diffraction * Rietveld refinement * nanoparticles Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 3.794, year: 2010

Multiscale Biological Materials

DEFF Research Database (Denmark)

Frølich, Simon

of multiscale biological systems have been investigated and new research methods for automated Rietveld refinement and diffraction scattering computed tomography developed. The composite nature of biological materials was investigated at the atomic scale by looking at the consequences of interactions between...

Synthesis of nano intermetallic Nb{sub 3}Sn by mechanical alloying and annealing at low temperature

Energy Technology Data Exchange (ETDEWEB)

López, M., E-mail: marlope@udec.cl [Department of Materials Engineering, Universidad de Concepción, Edmundo Larenas 270, Concepción (Chile); Jiménez, J.A. [Department of Physical Metallurgy, Centro Nacional de Investigaciones Metalúrgicas, C.S.I.C., Av. Gregorio del Amo 8, 28040 Madrid (Spain); Ramam, K.; Mangalaraja, R.V. [Department of Materials Engineering, Universidad de Concepción, Edmundo Larenas 270, Concepción (Chile)

2014-11-05

Highlights: • Intermetallic Nb{sub 3}Sn nano grains were synthesized by powder metallurgy route. • Structure analysis was studied using a multiphase Rietveld refinement fit. • The presence of Nb{sub 3}Sn 86% and NbO 8% was identified. • More tin content in the equilibrium Nb–Sn diagram was obtained. • Magnetic properties show Nb{sub 3}Sn powders are soft super paramagnetic materials. - Abstract: In this study, intermetallic Nb{sub 3}Sn of nanometer-sized grains was synthesized by powder metallurgy route. Elemental powders of Nb and Sn in the stoichiometric proportions were mechanically alloyed for 3 h in a high-energy mill under a protective atmosphere of argon. X-ray diffraction patterns of milled powders confirmed the formation of a Nb(Sn) solid solution evidenced by the presence of Nb peaks only, which are shifted to higher angles. Rietveld refinements used to analyze this XRD pattern indicated a better fit when a tetragonal structure with the space group I4/mmm is used instead the Nb cubic lattice with space group Im−3m. Size-strain analysis from line-broadening of peak profiles by using “double-Voigt” approaches showed that the broadening is due to both a small crystallite size (around 6 nm) and microstrains. Subsequent heat treatment of the Nb(Sn) powder mixture was required for the formation of the Nb{sub 3}Sn ordered phase. X-ray diffraction patterns obtained after a thermal treatment at 700 °C for 1 h were fitted using a multiphase Rietveld refinement. Although the resulting powders are composed mainly by Nb{sub 3}Sn (up to 87 weight%), certain amount of other intermetallic phases like Nb{sub 6}Sn{sub 5}, NbSn{sub 2} and Nb and Sn oxides were also determined. In agreement with the Rietveld refinement analysis, microprobe analysis also revealed that changes in chemical composition at different sites of powder particles are preserved even after annealing at 700 °C. Magnetic properties measured at 300 K on resulted Nb{sub 3}Sn powders

Analysis of the zirconia structure by 'ab initio' and Rietveld methods

International Nuclear Information System (INIS)

Bechepeche, A.P.; Nasar, R.S.; Longo, E.; Treu Junior, O.; Varela, J.A.

1995-01-01

The zirconia was doped with 0,113 mol of Mg O e 0,005 mol of Ti O 2 , and it was calcined in 1550 d eg C and it was analyzed by XRD. The results shows that pure zirconia contains 96,19% of monoclinic phase and 3,18% of cubic. However, the doping magnesia stabilizes the zirconia in 17,24 of monoclinic; 29,63 of tetragonal and 53,13% of cubic phase. The addition of titanium in zirconia gives 25,85% of tetragonal phase and 37,66% of cubic, and this shows the no stabilizing action of this transition metal. By the other side, the results with ab-initio calculating shows the same tendency resulting in the next values of total energy: pure zirconia - monoclinic -11.316,86ua; tetragonal -8742,09 ua and cubic -8742,80 ua and Zr O 2 Ti O 2 system - monoclinic -9463,02 ua, tetragonal -9459,39 ua and cubic -9459,97 ua (author)

Magnetic and ferroelectric characteristics of Gd 3 + and Ti 4 + co ...

Indian Academy of Sciences (India)

The crystallographicsite occupancies of Gd and Ti were confirmed by Rietveld refinement of XRD data,Mössbauer spectroscopy and magnetization measurements. An enhancement in ferromagnetic properties along with moderate ferroelectricproperties have been observed after co-doping. There was an increasing trend in ...

The iron member of the CPO-27 coordination polymer series: Synthesis, characterization, and intriguing redox properties

DEFF Research Database (Denmark)

Märcz, Matthias; Johnsen, Rune; Dietzel, Pascal D.C.

2012-01-01

The microporous coordination polymer CPO-27-Fe was synthesized from iron salts and 2,5-dihydroxyterephthalic acid by microwave assisted solvothermal synthesis. The crystal structures of the as-synthesized compounds were determined by Rietveld refinement from powder X-ray diffraction data using...

'The End of Sitting' : An Empirical Study on Working in an Office of the Future

NARCIS (Netherlands)

Withagen, Rob; Caljouw, Simone R.

Background Inspired by recent findings that prolonged sitting has detrimental health effects, Rietveld Architecture Art Affordances (RAAAF) and visual artist Barbara Visser designed a working environment without chairs and desks. This environment, which they called The End of Sitting, is a sculpture

RAAAF's office landscape The End of Sitting : Energy expenditure and temporary comfort when working in non-sitting postures

NARCIS (Netherlands)

Caljouw, Simone R.; de Vries, Rutger; Withagen, Rob

2017-01-01

An earlier study suggested that the activity-inviting office landscape called "The End of Sitting", designed by Rietveld Architecture Art Affordances (RAAAF), should be considered as an alternative working environment to prevent sedentary behavior. The End of Sitting lacks chairs and tables but

Quantitative analysis of retained austenite in laser melted martensitic stainless steel

CSIR Research Space (South Africa)

Seleka, T

2007-11-01

Full Text Available of this study was to determine if X-ray diffraction (XRD) was sufficient for quantifying the volume percentage of retained austenite. After a preliminary qualitative analysis, a Rietveld full pattern refinement program was used to quantify the volume percentage...

Interstitial positions of tin ions in alpha-(FerichSn)(2)O-3 solid solutions prepared by mechanical alloying

DEFF Research Database (Denmark)

Jiang, Jianzhong; Lin, Rong; Nielsen, Kurt

1997-01-01

The microstructure of samples of 91, 85, and 71 mol % alpha-Fe-2-O-3-SnO2. prepared by mechanical alloying, has been studied by x-ray diffraction with Rietveld structure refinements, On the basis of the structure refinements to the whole x-ray diffraction patterns for the four as-milled samples, ......, it is found that tin ions do not substitute iron ions in the solid solution, although this model is generally assumed in the literature. The Sn4+ ions occupy the empty octahedral holes in the lattice of the alpha-Fe2O3 phase.......The microstructure of samples of 91, 85, and 71 mol % alpha-Fe-2-O-3-SnO2. prepared by mechanical alloying, has been studied by x-ray diffraction with Rietveld structure refinements, On the basis of the structure refinements to the whole x-ray diffraction patterns for the four as-milled samples...

The peak in neutron powder diffraction

International Nuclear Information System (INIS)

Laar, B. van; Yelon, W.B.

1984-01-01

For the application of Rietveld profile analysis to neutron powder diffraction data a precise knowledge of the peak profile, in both shape and position, is required. The method now in use employs a Gaussian shaped profile with a semi-empirical asymmetry correction for low-angle peaks. The integrated intensity is taken to be proportional to the classical Lorentz factor calculated for the X-ray case. In this paper an exact expression is given for the peak profile based upon the geometrical dimensions of the diffractometer. It is shown that the asymmetry of observed peaks is well reproduced by this expression. The angular displacement of the experimental profile with respect to the nominal Bragg angle value is larger than expected. Values for the correction to the classical Lorentz factor for the integrated intensity are given. The exact peak profile expression has been incorporated into a Rietveld profile analysis refinement program. (Auth.)

The Embodied Brain: Towards a Radical Embodied Cognitive Neuroscience

Directory of Open Access Journals (Sweden)

Julian eKiverstein

2015-05-01

Full Text Available In this programmatic paper we explain why a radical embodied cognitive neuroscience is needed. We argue for such a claim based on problems that have arisen in cognitive neuroscience for the project of localizing function to specific brain structures. The problems come from research concerned with functional and structural connectivity that strongly suggests that the function a brain region serves is dynamic, and changes over time. We argue that in order to determine the function of a specific brain area, neuroscientists need to zoom out and look at the larger organism-environment system. We therefore argue that instead of looking to cognitive psychology for an analysis of psychological functions, cognitive neuroscience should look to an ecological dynamical psychology. A second aim of our paper is to develop an account of embodied cognition based on the inseparability of cognitive and emotional processing in the brain. We argue that emotions are best understood in terms of action readiness (Frijda 1986, 2007 in the context of the organism’s ongoing skillful engagement with the environment (Rietveld 2008; Bruineberg & Rietveld 2014; Kiverstein & Rietveld 2015. States of action readiness involve the whole living body of the organism, and are elicited by possibilities for action in the environment that matter to the organism. Since emotion and cognition are inseparable processes in the brain it follows that what is true of emotion is also true of cognition. Cognitive processes are likewise processes taking place in the whole living body of an organism as it engages with relevant possibilities for action.

Facile synthesis of B-type carbonated nanoapatite with tailored microstructure

Energy Technology Data Exchange (ETDEWEB)

Gualtieri, Magdalena Lassinantti, E-mail: magdalena.gualtieri@unimore.it [Dipartimento Ingegneria “Enzo Ferrari”, Università degli studi di Modena e Reggio Emilia, I-41125 Modena (Italy); Romagnoli, Marcello, E-mail: marcello.romagnoli@unimore.it [Dipartimento Ingegneria “Enzo Ferrari”, Università degli studi di Modena e Reggio Emilia, I-41125 Modena (Italy); Hanuskova, Miriam, E-mail: Miriam.hanuskova@unimore.it [Dipartimento Ingegneria “Enzo Ferrari”, Università degli studi di Modena e Reggio Emilia, I-41125 Modena (Italy); Fabbri, Elena, E-mail: Elena.fabbri@unimore.it [Dipartimento Ingegneria “Enzo Ferrari”, Università degli studi di Modena e Reggio Emilia, I-41125 Modena (Italy); Gualtieri, Alessandro F., E-mail: Alessandro.gualtieri@unimore.it [Dipartimento di Scienze Chimiche e Geologiche, Università degli studi di Modena e Reggio Emilia, I-41121 Modena (Italy)

2014-12-15

Nanolime and a phosphate-based chelating agent were used to synthesize B-type carbonated apatite. Developed Rietveld refinement strategies allowed one to determine process yield, product crystallinity as well as structural (unit cell) and microstructural (size, strain) parameters. The effect of synthesis temperature (20–60 °C) as well as Ca/P ratio (1.5–2.5) and solid content (10–30 wt%) of the starting batch on these properties were investigated. FTIR, TEM and gas adsorption data provided supporting evidence. The process yield was 42–60 wt% and found to be governed by the Ca/P ratio. The purified products had high specific surface area (107–186 m{sup 2}/g) and crystallinity (76–97%). The unit cell parameters, correlated to the degree of structural carbonate, were sensitive to the Ca/P ratio. Instead, temperature governed the microstructural parameters. Less strained and larger crystals were obtained at higher temperatures. Long-term aging up to 6 months at 20 °C compensated for higher crystal growth kinetics at higher temperature. - Graphical abstract: Controlled synthesis of carbonated apatite at moderate temperatures using nanolime and sodiumhexametaphosphate as starting reagent. - Highlights: • Chemical synthesis of nano-sized apatite with tailored microstructure was performed. • Colloidal Ca(OH){sub 2} and a phosphorus-based chelating agents were used as reagents. • The method is simple and reproducible which facilitate industrial process scale-up. • Rietveld refinement strategies for product characterization were developed. • Rietveld analyses provided yield, microstructural and structure information.

Facile synthesis of B-type carbonated nanoapatite with tailored microstructure

International Nuclear Information System (INIS)

Gualtieri, Magdalena Lassinantti; Romagnoli, Marcello; Hanuskova, Miriam; Fabbri, Elena; Gualtieri, Alessandro F.

2014-01-01

Nanolime and a phosphate-based chelating agent were used to synthesize B-type carbonated apatite. Developed Rietveld refinement strategies allowed one to determine process yield, product crystallinity as well as structural (unit cell) and microstructural (size, strain) parameters. The effect of synthesis temperature (20–60 °C) as well as Ca/P ratio (1.5–2.5) and solid content (10–30 wt%) of the starting batch on these properties were investigated. FTIR, TEM and gas adsorption data provided supporting evidence. The process yield was 42–60 wt% and found to be governed by the Ca/P ratio. The purified products had high specific surface area (107–186 m 2 /g) and crystallinity (76–97%). The unit cell parameters, correlated to the degree of structural carbonate, were sensitive to the Ca/P ratio. Instead, temperature governed the microstructural parameters. Less strained and larger crystals were obtained at higher temperatures. Long-term aging up to 6 months at 20 °C compensated for higher crystal growth kinetics at higher temperature. - Graphical abstract: Controlled synthesis of carbonated apatite at moderate temperatures using nanolime and sodiumhexametaphosphate as starting reagent. - Highlights: • Chemical synthesis of nano-sized apatite with tailored microstructure was performed. • Colloidal Ca(OH) 2 and a phosphorus-based chelating agents were used as reagents. • The method is simple and reproducible which facilitate industrial process scale-up. • Rietveld refinement strategies for product characterization were developed. • Rietveld analyses provided yield, microstructural and structure information

Effect of Cu{sup 2+} and Ni{sup 2+} substitution at the Mn site in (La{sub 0.63}Ca{sub 0.37})MnO{sub 3}: A neutron powder diffraction investigation

Energy Technology Data Exchange (ETDEWEB)

Martinelli, A., E-mail: alberto.martinelli@spin.cnr.it [CNR-SPIN, C.so Perrone 24, 16152 Genova (Italy); Ferretti, M. [CNR-SPIN, C.so Perrone 24, 16152 Genova (Italy); Dipartimento di Chimica e Chimica Industriale, Università di Genova, Via Dodecaneso 31, 16146 Genova (Italy); Castellano, C. [Università degli Studi di Milano, Dipartimento di Chimica Strutturale e Stereochimica Inorganica, Via G. Venezian 21, 20133 Milano (Italy); Cimberle, M.R. [IMEM-CNR, Via Dodecaneso 33, 16146 Genova (Italy); Ritter, C. [Institute Laue—Langevin, 6 rue Jules Horowitz, 38042 Grenoble Cedex 9 (France)

2013-04-15

The crystal and magnetic structures of the (La{sub 0.63}Ca{sub 0.37})(Mn{sub 1−x}TM{sub x})O{sub 3} compounds (x=0.00, 0.03, 0.08; TM=Cu{sup 2+}, Ni{sup 2+}) were investigated between 5 K and 300 K by means of dc magnetic measurements and neutron powder diffraction analysis followed by Rietveld refinement. Both substituting cations lead to a reduction of the long range ferromagnetic ordering temperature; ferromagnetism is strongly suppressed in the 8% Cu-substituted sample, where long- and short-range FM magnetic orders coexist together with short-range A-type AFM order. This particular feature can be related to the Jahn–Teller character of Cu{sup 2+}, absent in Ni{sup 2+}, and suggests the occurrence of a quantum critical point in the (La{sub 0.63}Ca{sub 0.37})(Mn{sub 1−x}Cu{sub x})O{sub 3} system. - Graphical abstract: Rietveld refinement plot of (La{sub 0.63}Ca{sub 0.37})(Mn{sub 0.92}Cu{sub 0.08})O{sub 3} showing in the inset the coexistence of broad A-type AFM peaks with FM ones. Highlights: ► (La{sub 0.63}Ca{sub 0.37})MnO{sub 3} was substituted with Ni and Cu. ► Neutron powder diffraction and Rietveld refinement were carried out. ► A quantum critical point possibly occurs in the (La{sub 0.63}Ca{sub 0.37})(Mn{sub 1−x}Cu{sub x})O{sub 3} system.

Computation of X-ray powder diffractograms of cement components ...

Indian Academy of Sciences (India)

Computation of X-ray powder diffractograms of cement components and its application to phase analysis and hydration performance of OPC cement. Rohan Jadhav N C Debnath. Volume 34 Issue 5 August 2011 pp 1137- ... Keywords. Portland cement; X-ray diffraction; crystal structure; characterization; Rietveld method.

Aproximación a un modelo de indicadores de alerta temprana considerando la función de pérdida del Banco Central

OpenAIRE

Armagno, Daniel; García Fronti, Javier; Rey, Sebastián

2004-01-01

Nuestro interés en este trabajo es estudiar las causas que llevan al debilitamiento de las entidades bancarias. Para ello incluiremos en el análisis, al responsable de la toma de decisiones del Banco Central que tiene en consideración una función de pérdida del tipo desarrollada en Dermirgüç–Kunt, A. and E. Detragiache (1999). Aplicando un modelo logit y evaluamos los resultados obtenidos.

On the Stress-Induced Formation of R-Phase in Ultra-Fine-Grained Ni-Rich NiTi Shape Memory Alloys

Czech Academy of Sciences Publication Activity Database

Olbricht, J.; Yawny, A.; Pelegrina, J.L.; Dlouhý, Antonín

42A, č. 9 (2011), s. 2556-2574 ISSN 1073-5623 R&D Projects: GA ČR GA106/09/1913 Institutional research plan: CEZ:AV0Z20410507 Keywords : martensitic transformations * rietveld method * single-crystals Subject RIV: JG - Metallurgy Impact factor: 1.545, year: 2011

Electronic structure and magnetic properties of FeWO{sub 4} nanocrystals synthesized by the microwave-hydrothermal method

Energy Technology Data Exchange (ETDEWEB)

Almeida, M.A.P. [INCTMN-DQ-Universidade Federal de Sao Carlos, Sao Carlos, P.O. Box 676, 13565-905, SP (Brazil); Cavalcante, L.S., E-mail: laeciosc@bol.com.br [INCTMN-Universidade Estadual, Paulista, P.O. Box 355, 14801-907, Araraquara, SP (Brazil); Morilla-Santos, C.; Filho, P.N. Lisboa [MAv-Universidade Estadual, Paulista, P.O. Box 473, 17033-360, Bauru, SP (Brazil); Beltran, A.; Andres, J.; Gracia, L. [Department de Quimica Fisica i Analitica, Universitat Jaume I, E-12071 Castello (Spain); Longo, E. [INCTMN-DQ-Universidade Federal de Sao Carlos, Sao Carlos, P.O. Box 676, 13565-905, SP (Brazil); INCTMN-Universidade Estadual, Paulista, P.O. Box 355, 14801-907, Araraquara, SP (Brazil)

2012-11-15

This communication reports that FeWO{sub 4} nanocrystals were successfully synthesized by the microwave-hydrothermal method at 443 K for 1 h. The structure and shape of these nanocrystals were characterized by X-ray diffraction, Rietveld refinement, and transmission electron microscopy. The experimental results and first principles calculations were combined to explain the electronic structure and magnetic properties. Experimental data were obtained by magnetization measurements for different applied magnetic fields. Theoretical calculations revealed that magnetic properties of FeWO{sub 4} nanocrystals can be assigned to two magnetic orderings with parallel or antiparallel spins in adjacent chains. These factors are crucial to understanding of competition between ferro- and antiferromagnetic behavior. Highlights: Black-Right-Pointing-Pointer Monophasic FeWO{sub 4} nanocrystals were synthesized by the microwave-hydrothermal method. Black-Right-Pointing-Pointer Rietveld refinement and clusters model for monoclinic structure Black-Right-Pointing-Pointer Magnetic properties of FeWO{sub 4} nanocrystals at different temperatures.

Crystal structure and magnetic properties of La2−x(Sr0.5Ca0.5)1+xMn2O7 (x=0.6, 0.8 and 1.0) Ruddlesden–Popper manganites

International Nuclear Information System (INIS)

Raju, K.; Song, M.S.; Lee, J.Y.

2014-01-01

Double layer perovskite (Ruddlesden–Popper) manganites with the nominal composition of La 2−x (Sr 0.5 Ca 0.5 ) 1+x Mn 2 O 7 (x=0.6, 0.8 and 1.0) were synthesized via a solid state reaction route. X-ray and neutron diffraction were performed at room temperature and the crystal structure was refined using the Rietveld method based on the space group, I4/mmm. The temperature variation of the susceptibility revealed a spin glass transition at 28 K for x=0.6, a charge ordering transition at 245 K and a Neel transition at 170 K for x=1.0. - Highlights: • Lanthanum based double layered manganites were prepared by doping with the same amounts of Sr and Ca. • X-ray and neutron diffraction were performed and the crystal structure was refined using the Rietveld method. • Different magnetic transitions were observed depending upon the doping concentration. • Qualitative explanation for the various observed phenomena was given

Structures and solid solution mechanisms of pyrochlore phases in the systems Bi2O3-ZnO-(Nb, Ta)2O5

International Nuclear Information System (INIS)

Tan, K.B.; Khaw, C.C.; Lee, C.K.; Zainal, Z.; Miles, G.C.

2010-01-01

Research highlights: → Combined XRD and ND Rietveld structural refinement of pyrochlores. → Structures and solid solution mechanisms of Bi-pyrochlores. → Bi and Zn displaced off-centre to different 96g A-site positions. → Summary of composition-structure-property of Bi-pyrochlores. - Abstract: The crystal structures of two pyrochlore phases have been determined by Rietveld refinement of combined X-ray and neutron powder diffraction data. These are stoichiometric, Bi 1.5 ZnTa 1.5 O 7 and non-stoichiometric Bi 1.56 Zn 0.92 Nb 1.44 O 6.86 . In both structures, Zn is distributed over A- and B-sites; Bi and Zn are displaced off-centre, to different 96g A-site positions; of the three sets of oxygen positions, O(1) are full, O(2) contain vacancies and O(3) contain a small number of oxygen, again in both cases. Comparisons between these structures, those of related Sb analogues and literature reports are made.

First-principles calculation on electronic properties of zinc oxide by zinc–air system

Directory of Open Access Journals (Sweden)

Ahmad Azmin Mohamad

2017-07-01

Full Text Available First-principles calculations are performed to study the electronic properties of zinc oxide (ZnO formed on an anode after discharging a Zn–air system. Prior to calculation, the ZnO is characterised by X-ray diffraction using Rietveld refinement. Diffracted patterns proved the formation of single phase ZnO, while Rietveld analysis shows that the ZnO has a hexagonal wurtzite structure with lattice parameters, a = 3.244 and c = 5.199 Å. Geometry optimisation of the hexagonal wurtzite structure of the ZnO is performed using various exchange–correlation energy functionals. The local density approximation functional method is used to explain the structure, electronic band structure and density of state properties of hexagonal ZnO. The calculated energy band gap was 0.75 eV while the density of states reveals that the O 2p (the top valence band and Zn 4s (the bottom conduction band states domination.

Synthesis, structural and electrical characterizations of DySr.sub.5./sub.Ni.sub.2.4./sub.Cu.sub.0.6./sub.O.sub.12-δ./sub..

Czech Academy of Sciences Publication Activity Database

Hamdi, S.; Ouni, S.; Chaker, H.; Rohlíček, Jan; Ben Hassen, R.

2011-01-01

Roč. 184, č. 11 (2011), s. 2897-2901 ISSN 0022-4596 Institutional research plan: CEZ:AV0Z10100521 Keywords : Rietveld refinement * K 2 NiF 4 -type structure * electrical resistivity * oxygen vacancies * iodometric titration Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.159, year: 2011

Structural and electrical properties of Nd.sub.1.7./sub.Ba.sub.0.3./sub.Ni.sub.0.9./sub.Cr.sub.0.1./sub.O.sub.4+δ./sub. compound

Czech Academy of Sciences Publication Activity Database

Jammali, M.; Hassen, R.B.; Rohlíček, Jan

2012-01-01

Roč. 27, č. 3 (2012), s. 184-188 ISSN 0885-7156 Institutional research plan: CEZ:AV0Z10100521 Keywords : X-ray diffraction * sol-gel * Rietveld refinement * adiabatic small polaron hopping model * semi-conductive behaviour Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 0.544, year: 2012

Assessment of the potential hazard represented by natural raw materials containing mineral fibres -The case of the feldspar from Orani, Sardinia (Italy)

Czech Academy of Sciences Publication Activity Database

Gualtieri, A. F.; Gandolfi, N. B.; Pollastri, S.; Rinaldi, R.; Sala, O.; Martinelli, G.; Bacci, T.; Paoli, F.; Viani, Alberto; Vigliaturo, R.

2018-01-01

Roč. 350, May (2018), s. 76-87 ISSN 0304-3894 R&D Projects: GA MŠk(CZ) LO1219 Keywords : feldspar * tremolite * Rietveld * SEM * EMPA Subject RIV: DB - Geology ; Mineralogy OBOR OECD: Mineralogy Impact factor: 6.065, year: 2016 https://www.sciencedirect.com/science/article/pii/S0304389418300888

Methane storage mechanism in the metal-organic framework Cu3(btc)2: An in situ neutron diffraction study

NARCIS (Netherlands)

Getzschmann, J.; Senkovska, I.; Wallacher, D.; Tovar, M.; Fairen-Jimenez, D.; Düren, T.; van Baten, J.M.; Krishna, R.; Kaskel, S.

2010-01-01

The adsorption of deutero-methane (CD4) in Cu3(btc)2 (HKUST-1) was investigated at 77 K using high-resolution neutron powder diffraction. Rietveld refinement of the neutron data revealed a sequential filling of the rigid framework at distinct preferred adsorption sites, and showed the importance of

Thermoelastic and structural properties of ionically conducting cerate perovskites: (II) SrCeO3 between 1273 K and 1723 K

DEFF Research Database (Denmark)

Knight, Kevin S.; Haynes, Richard; Bonanos, Nikolaos

2015-01-01

The temperature dependence of the crystal structure and the thermoelastic properties of SrCeO3 have been determined from Rietveld refinement of high resolution, neutron time-of-flight powder diffraction data collected in 5 K intervals between 1273 K and 1723 K. No evidence was found for critical ...

Investigation on the formation of Cu-Fe nano crystalline super-saturated solid solution developed by mechanical alloying

Energy Technology Data Exchange (ETDEWEB)

Mojtahedi, M., E-mail: m.mojtahedi@gmail.com [School of Materials Science and Engineering, Iran University of Science and Technology, Narmak, Tehran 16846-13114 (Iran, Islamic Republic of); Goodarzi, M.; Aboutalebi, M.R. [School of Materials Science and Engineering, Iran University of Science and Technology, Narmak, Tehran 16846-13114 (Iran, Islamic Republic of); Ghaffari, M. [Department of Electrical and Electronics Engineering, UNAM-Institute of Materials Science and Nanotechnology, Bilkent University, Ankara 06800 (Turkey); Soleimanian, V. [Department of Physics, Faculty of Science, Shahrekord University, P.O. Box 115, Shahrekord (Iran, Islamic Republic of)

2013-02-15

Highlights: Black-Right-Pointing-Pointer The deformation of the mechanically alloyed Cu-Fe powder is anisotropic. Black-Right-Pointing-Pointer The Rietveld method is more proper and results in smaller crystallite size than the Scherer and Williamson-Hall methods. Black-Right-Pointing-Pointer A dual phase super saturated solid solution achieved after 96 h of milling of the mixtures with 30, 50 and 70 wt.% of Iron. Black-Right-Pointing-Pointer A final proportion of approximately 85% FCC and 15% BCC structure obtained in all of the applied compositions. - Abstract: In this study, the formation of super saturated solid solution in the binary Cu-Fe system was investigated. Three powder blends with 30, 50 and 70 wt.% of Fe were milled for different times to 96 h. The variations of lattice parameter and inter-planar spacing were calculated and analyzed using X-ray diffraction analysis (XDA). The anisotropy of lattice deformation in the FCC phase was studied and the obtained results were compared to milled pure Cu powder. Furthermore, crystallite size was calculated using Scherer formula in comparison with Rietveld full profile refinement method. Considering the previous studies about the formation of non-equilibrium FCC and BCC phases, the phase evolution has been discussed and the proportion of each phase was calculated using Rietveld refinement method. Supplementary studies on the evolution of microstructure and formation of solid solution were carried out using high resolution transmission electron microscopy (HRTEM). Finally, high angle annular dark field (HAADF) imaging was utilized to find out the level of homogeneity in the resulting phases. While true alloying takes place in each phase, the final structure consists of both FCC and BCC nano-crystallites.

Estudio y desarrollo de procesos de soporte de negocio en una empresa española perteneciente al sector de las infraestructuras, servicios, ingeniería y sistemas.

OpenAIRE

Porcar Tremps, Víctor

2010-01-01

El presente proyecto tiene como objetivo principal estudiar y desarrollar procesos de soporte de negocio de una multinacional española, cuya actividad principal es el negocio de las infraestructuras. Las empresas llevan tiempo trabajando para alcanzar la máxima excelencia en la gestión de sus procesos, y para ello han ido aplicando progresivamente los diferentes avances tecnológicos que han ido surgiendo. En este caso la herramienta utilizada es un sistema BPM (Business Process...

Análisis de la estabilidad actual de la ermita sur en la Hidroeléctrica Mazar

OpenAIRE

Almache Sánchez, Luis Mario

2014-01-01

La Hidroeléctrica Mazar presenta varios problemas relacionados con taludes inestables que afectan su normal funcionamiento y representan un riesgo para la represa construida. El presente trabajo analiza la estabilidad de la ladera La Ermita Sur ubicado aguas arriba de la presa en el que diferentes factores desencadenaron un movimiento de esta masa. Se realizó una modelación por medios computacionales del talud, analizando como factor primordial desencadenante el agua. Aplicando el mét...

Análisis, diseño, desarrollo e implementación de políticas y procedimientos para la gestión de los servidores. Caso de estudio: Centro de Investigación IDE-GEOCA.

OpenAIRE

Jiménez Erazo, Darwin Ramiro; Osorio Duque, Marcelo Paúl

2016-01-01

This project is a case study, where we do an analysis of security by opensource tools, applying OSSTMM and ethical hacking methodology, allowing to identify vulnerabilities in the infrastructure and showing corresponding to each mitigations, defining a scheme basis for the implementation of security policies for the IDE-IA-GEOCA..research..center. El presente proyecto, es un caso de estudio, donde realizamos un análisis de seguridad informática mediante herramientas opensource, aplicando m...

Control borroso para la valoración del impacto ambiental generado por contaminantes emergentes en aguas residuales hospitalarias

OpenAIRE

Leadina Sánchez Barboza

2015-01-01

La valoración de impactos ambientales está sujeta a imprecisión, vaguedad y subjetividad. Estas características son extensivas al impacto generado por la presencia de contaminantes emergentes -fármacos- en aguas residuales hospitalarias, por lo que este trabajo propone valorar el impacto de dichos contaminantes mediante un sistema de inferencia borrosa, utilizando el toolbox fuzzy logic de MATLAB®, aplicando el sistema experto Mamdani. Los conjuntos borrosos de entrada se establecieron a part...

Structural and compositional stability of the mechanically alloyed (Fe,Mo)-Al at elevated temperatures

Czech Academy of Sciences Publication Activity Database

Jirásková, Yvonna; Buršík, Jiří; Roupcová, Pavla; Jančík, D.; Čížek, J.

2015-01-01

Roč. 168, NOV (2015), s. 108-116 ISSN 0254-0584 R&D Projects: GA MŠk(CZ) ED1.1.00/02.0068 Institutional support: RVO:68081723 Keywords : Magnetic properties * Electron microscopy * Rietveld analysis * Phase transitions Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 2.101, year: 2015

HgO-added YBa2Cu3O7− δ superconductors

Indian Academy of Sciences (India)

The structural studies were carried out by neutron scattering and Rietveld analysis. The neutron scattering revealed that Hg is not incorporated in the Y-123 system and has shown optimum oxygen concentration. The significant role played by the HgO is to provide oxygen ambient through its decomposition, thus changing ...

Magnetic ordering in the rare earth iron germanates HoFeGe2O7 and ErFeGe2O7

DEFF Research Database (Denmark)

Cascales, C.; Puebla, E.G.; Klimin, S.

1999-01-01

RFeGe2O7 (R = Ho, Er) have been prepared in polycrystalline form, and their crystal structures have been refined from room-temperature high-resolution neutron diffraction data by the Rietveld method. Both materials are isostructural, space group P2(1)/m (no. 11), Z = 4. The most interesting feature...

Quantitative X-ray diffraction analysis of development of Z phase in 12%Cr–Nb–V–N steel

DEFF Research Database (Denmark)

Di Nunzio, P. E.; Cipolla, L.; Vipraio, S. Tiberi

2010-01-01

. A quantitative determination of the volume fractions of the extracted nitrides that had formed after aging treatments at 650uC for up to 10 000 h was carried out by an X-ray diffraction procedure, based on the Rietveld approach. The investigation of the Z phase evolution by the Johnson...

Synthesis, structure and thermoelectric properties of La1 ...

Indian Academy of Sciences (India)

Structural parameters for all the compounds were confirmed by the Rietveld refinement method usingpowder X-ray diffraction (XRD) data and exhibit the rhombhohedral crystal structure with space group R-3c (No. 167). Thescanning electron microscopy study reveals that the particles are spherical in shape and sizes, in the ...

Quantitative Mineralogical Analysis of Mars Analogues Using CHEMIN Data and Rietveld Refinement

Science.gov (United States)

Bish, D. L.; Sarrazin, P.; Chipera, S. J.; Vaniman, D. T.; Blake, D.

2004-01-01

Mineralogical analysis is a critical component of planetary surface exploration. Chemical data alone leave serious gaps in our understanding of the surfaces of planets where complex minerals may form in combination with H, S, and halogens. On such planets (e.g., Mars) a single chemical composition may represent a range of mineral assemblages. For example, Viking chemical analyses of excavated duricrust indicate that Mg and S are correlated and 10% MgSO4 (anhydrous weight) is a likely cementing agent. Pathfinder chemical data support a similar abundance of MgSO4 in the most altered materials. However, there are many possible Mg-sulfates with widely varying hydration states (including dehydrated and 1-, 2-, 3-, 4-, 5-, 6-, and 7-hydrates). In addition, other sulfate minerals such as gypsum (CaSO4 .2H2O) and other salts containing Cl may also exist. X-ray diffraction (XRD) has the ability to decipher mixtures of these phases that would be difficult, if not impossible to unravel using only chemical or spectral data.

Rietveld refinement of KLaTiO4 from X-ray powder data

Directory of Open Access Journals (Sweden)

Bai-Chuan Zhu

2011-04-01

Full Text Available Potassium lanthanum titanate(IV, KLaTiO4, has been synthesized by conventional solid-state reaction. It crystallizes isotypically with the NaLnTiO4 (Ln = La, Pr, Nd, Sm, Eu, Gd, Y and Lu family. Five of the six atoms in the asymmetric unit (one K, one La, one Ti and two O atoms are situated on sites with 4mm symmetry, whereas one O atom has 2mm. site symmetry. The crystal structure can be described as being composed of single layers of distorted corner-sharing TiO6 octahedra extending parallel to (001. The layers are alternately separated by K+ and La3+ cations along [001]. The coordination number of both K+ and La3+ cations is nine, resulting in distorted KO9 and LaO9 polyhedra.

Implementar Balanced Scorecard en una entidad financiera aplicando tecnologías Business Intelligence

OpenAIRE

Mendoza Villegas, María Milagros; Mendoza Villegas, María Milagros

2008-01-01

Hoy en día las organizaciones necesitan mantener la excelencia estratégica y operativa, para sobrevivir y enfrentar futuros desafíos. La presión de la competencia, las necesidades de obtener mejores resultados obligan a las organizaciones a asegurarse que las estrategias trazadas estén ejecutándose correctamente y que alcancen los niveles de eficiencia operativa para asegurar el éxito. Un aliado importante para lograr alcanzar el éxito es el Balanceé Scorecard (BSC), la herramienta de plan...

Arquitectura software para robots móviles aplicando la metodología mdasr

OpenAIRE

Londoño Ospina, Nelson de J.

2011-01-01

Se aplica la Metodología de Desarrollo de Arquitecturas Software para Robots –MDASR, como herramienta de especificación, análisis y diseño de una Arquitectura de Control Reactiva. La metodología se apoya en métodos y lenguajes ampliamente adoptados como el P U (Proceso Unificado de Desarrollo de Software) y UML (Lenguaje Unificado de Modelado), apropiando conceptos y métodos empleados en Ingeniería Software

Chemical and structural characterization of natural phosphate of ...

African Journals Online (AJOL)

Powder X-ray diffraction fitting results confirm that compound belongs to the apatite family crystallising in the hexagonal system, space group P63/m. The cell parameters are: a = 9.3547(5) Å; c = 6.8929(4) Å. KEY WORDS: Natural phosphate, Fluoroapatite, Infrared, X-Ray diffraction, Rietveld structure refinement. Bull. Chem ...

Synthesis, structural and ferromagnetic properties of La1–x Kx ...

Indian Academy of Sciences (India)

2016-08-26

Aug 26, 2016 ... Synthesis, structural and ferromagnetic properties of La1–KMnO3 (0.0≤ 0.25) phases by solution combustion method ... Structural parameters were determined by the Rietveld refinement method using powder XRD data. Parent ... The ratio of the Mn3+/Mn4+ was determined by the iodometric titration.

Bulletin of Materials Science | Indian Academy of Sciences

Indian Academy of Sciences (India)

Finally microstructural defect parameters such as domain size (), r.m.s. microstrain 〈 2 〉1/2, twin fault ('), spacing fault () and deformation stacking fault () were evaluated in these alloys by Fourier line shape analysis using Rietveld method in which the X-ray diffraction profiles of these alloys were described by the ...

Diseño de un prototipo de volante para un vehículo tipo formula SAE mediante técnicas de optimización estructural

OpenAIRE

Picón Mejía, Jaime Andrés

2016-01-01

En este proyecto técnico se presenta una metodología para el diseño y construcción de un prototipo de volante de dirección para un vehículo tipo formula SAE, aplicando técnicas de optimización estructural considerando procesos de manufactura aditiva. In this technical project, a methodology is presented for the design and construction of a prototype steering wheel for a Formula SAE vehicle, using structural optimization techniques considering additive manufacturing processes.

Perfil psicosocial de la persona emprendedora

OpenAIRE

Trejo López, Enrique Alberto

2015-01-01

El objeto de la tesis es estudiar el perfil psicosocial de la persona emprendedora y de la emprendedora que continúa a pesar de la crisis, constatando las diferencias respecto al resto de los grupos laborales. Se realiza un estudio multidimensional, psicosocial, de nivel descriptivo y analítico, con un carácter longitudinal, aplicando instrumentos y metodologías cualitativas y cuantitativas y aportando datos disgregado por sexo En el marco teórico recogemos los estudios e investigacion...

Estudio del riesgo de los suelos contaminados con metales pesados para las infraestructuras de hormigón y valorización de dichos suelos mediante fabricación de morteros con aditivos calizos : aplicación en la Bahía de Portman

OpenAIRE

Meseguer Serrano, Fernando

2016-01-01

El potente desarrollo experimentado por los paises a nivel mundial durante el siglo pasado, ha generado una fuerte competencia por los recursos naturales que ha hecho insostenible el uso actual del suelo. A nivel europeo se pretende aliviar estas tensiones reintroduciendo en el proceso productivo los residuos susceptibles de ser valorizados, aplicando políticas que tienden a buscar un equilibrio entre prevenir la contaminación actual y recuperar la pasada, y están basadas en los principio...

¡Te lo creíste! Sobre cómo la información falsa se introduce en nuestra memoria

OpenAIRE

Malen Migueles; Karlos Luna

2008-01-01

La incorporación de información falsa en la memoria de un suceso delictivo puede alterar el subsiguiente testimonio. Para estudiar la aceptación de tres tipos diferentes de información falsa se realizaron tres experimentos aplicando el paradigma de la información engañosa. Los resultados señalan que los detalles (vs. acciones), los contenidos periféricos (vs. centrales) y la información de tipicidad alta (vs. baja) se aceptan con mayor facilidad.

Absorción de soluciones preservantes de nueve especies de maderas, mediante procesos de impregnación a vacío - presión e inmersión

OpenAIRE

R. Machuca-Velasco; M. Fuentes-Salinas; A. Borja-de la Rosa

2006-01-01

El presente trabajo se realizó con la finalidad de conocer la capacidad de absorción de preservadores de las maderas de Pinus arizonica (pino blanco), Pinus engelmanni (pino real), Pinus patula (pino colorado), Ceiba pentandra (ceiba), Manilkara zapota (chicozapote), Spondias mombin (jobo), Quercus insignis (chicalaba), Quercus laurina (laurelillo) y Quercus oleoides (tesmol), aplicando los procesos de impregnación vacío-presión e inmersión con sales CCA (cobre, cromo, arsénico) tipo...

Evaluación de destinos turísticos mediante la tecnología de la ciencia de datos

OpenAIRE

Amaya Molinar, Carlos Mario; Magaña Espinoza, Pedro; Ochoa Llamas, Ileana

2017-01-01

Se presentan resultados de un estudio exploratorio aplicando una metodología de Big Data a dos destinos turísticos mexicanos, utilizando la modalidad de análisis de sentimientos y opiniones en comentarios publicados en línea sobre cuatro modalidades de servicios turísticos: atractivos turísticos, hospedaje, alimentos y bebidas y transporte. La metodología emite evaluaciones positivas, negativas y neutrales sobre cada uno de los establecimientos y servicios analizados; los datos se tomaron de ...

Local structure and disorder in crystalline Pb9Al8O21

International Nuclear Information System (INIS)

Hannon, Alex C.; Barney, Emma R.; Holland, Diane; Knight, Kevin S.

2008-01-01

Crystalline Pb 9 Al 8 O 21 is a model compound for the structure of non-linear optical glasses containing lone-pair ions, and its structure has been investigated by neutron powder diffraction and total scattering, and 27 Al magic angle spinning NMR. Rietveld analysis (space group Pa3-bar (No. 205), a=13.25221(4) A) shows that some of the Pb and O sites have partial occupancies, due to lead volatilisation during sample preparation, and the non-stoichiometric sample composition is Pb 9-δ Al 8 O 21-δ with δ=0.54. The NMR measurements show evidence for a correlation between the chemical shift and the variance of the bond angles at the aluminium sites. The neutron total correlation function shows that the true average Al-O bond length is 0.8% longer than the apparent bond length determined by Rietveld refinement. The thermal variation in bond length is much smaller than the thermal variation in longer interatomic distances determined by Rietveld refinement. The total correlation function is consistent with an interpretation in which AlO 3 groups with an Al-O bond length of 1.651 A occur as a result of the oxygen vacancies in the structure. The width of the tetrahedral Al-O peak in the correlation function for the crystal is very similar to that for lead aluminate glass, indicating that the extent of static disorder is very similar in the two phases. - Graphical abstract: Combined neutron powder diffraction and total scattering, and 27 Al NMR on crystalline Pb 9 Al 8 O 21 shows it to be a non-stoichiometric compound with vacancies due to PbO volatilisation. A detailed consideration of the thermal and static disorder is given, showing that glass and crystal phases have very similar disorder at short range

Structures and solid solution mechanisms of pyrochlore phases in the systems Bi{sub 2}O{sub 3}-ZnO-(Nb, Ta){sub 2}O{sub 5}

Energy Technology Data Exchange (ETDEWEB)

Tan, K.B., E-mail: tankb@science.upm.edu.m [Department of Chemistry, Faculty of Science, Universiti Putra Malaysia, 43400 Serdang, Selangor (Malaysia); Khaw, C.C. [Department of Engineering, Universiti Tunku Abdul Rahman, 53300 Setapak, Kuala Lumpur (Malaysia); Lee, C.K. [Academic Science Malaysia, 902-4 Jalan Tun Ismail, 50480 Kuala Lumpur (Malaysia); Zainal, Z. [Department of Chemistry, Faculty of Science, Universiti Putra Malaysia, 43400 Serdang, Selangor (Malaysia); Miles, G.C. [Department of Engineering Materials, The University of Sheffield, Mappin Street, Sheffield, S1 3JD (United Kingdom)

2010-10-22

Research highlights: {yields} Combined XRD and ND Rietveld structural refinement of pyrochlores. {yields} Structures and solid solution mechanisms of Bi-pyrochlores. {yields} Bi and Zn displaced off-centre to different 96g A-site positions. {yields} Summary of composition-structure-property of Bi-pyrochlores. - Abstract: The crystal structures of two pyrochlore phases have been determined by Rietveld refinement of combined X-ray and neutron powder diffraction data. These are stoichiometric, Bi{sub 1.5} ZnTa{sub 1.5}O{sub 7} and non-stoichiometric Bi{sub 1.56}Zn{sub 0.92}Nb{sub 1.44}O{sub 6.86}. In both structures, Zn is distributed over A- and B-sites; Bi and Zn are displaced off-centre, to different 96g A-site positions; of the three sets of oxygen positions, O(1) are full, O(2) contain vacancies and O(3) contain a small number of oxygen, again in both cases. Comparisons between these structures, those of related Sb analogues and literature reports are made.

Dielectric and magnetic characterization of the electroceramic Ba2Co2Fe12O22 doped with Bi2O3 for applications in electronics components

International Nuclear Information System (INIS)

Pires Junior, G.F.M.; Sales, A.J.M.; Rodrigues, H.O.; Sombra, A.S.B.

2012-01-01

The objective of this work is to study the dielectric and magnetic properties of electroceramics (Ba 2 Co 2 Fe 12 O 22 - Co 2 Y) doped with (3; 5 and 10 wt%) of Bi 2 O 3 in order to promote better dielectric and magnetic properties for applications in electronics. Phase Co 2 Y was obtained through the method of solid-state reaction. The structural characterization was performed by X-ray Diffraction using the Rietveld refinement. Magnetic hysteresis curves of the samples were obtained at room temperature. The Impedance Spectroscopy was used in the study of the dielectric function of frequency in the range 100-100 MHz, at room temperature. It follows that the Rietveld refinement confirmed the structure to the hexagonal crystalline phase obtained. The curve analysis confirmed the magnetic hysteresis behavior of the ferrimagnetic samples. Furthermore, the samples showed large values of dielectric permittivity (30.8) and small dielectric loss (3,66 x10 -1 ) at 100 MHz for the sample B1, making them passive miniaturization. (author)

Crystal structure and magnetic properties of La{sub 2−x}(Sr{sub 0.5}Ca{sub 0.5}){sub 1+x}Mn{sub 2}O{sub 7} (x=0.6, 0.8 and 1.0) Ruddlesden–Popper manganites

Energy Technology Data Exchange (ETDEWEB)

Raju, K.; Song, M.S.; Lee, J.Y., E-mail: jylee@yu.ac.kr

2014-05-01

Double layer perovskite (Ruddlesden–Popper) manganites with the nominal composition of La{sub 2−x}(Sr{sub 0.5}Ca{sub 0.5}){sub 1+x}Mn{sub 2}O{sub 7} (x=0.6, 0.8 and 1.0) were synthesized via a solid state reaction route. X-ray and neutron diffraction were performed at room temperature and the crystal structure was refined using the Rietveld method based on the space group, I4/mmm. The temperature variation of the susceptibility revealed a spin glass transition at 28 K for x=0.6, a charge ordering transition at 245 K and a Neel transition at 170 K for x=1.0. - Highlights: • Lanthanum based double layered manganites were prepared by doping with the same amounts of Sr and Ca. • X-ray and neutron diffraction were performed and the crystal structure was refined using the Rietveld method. • Different magnetic transitions were observed depending upon the doping concentration. • Qualitative explanation for the various observed phenomena was given.

Analysis of neutron diffraction spectra acquired in situ during stress-induced transformations in superelastic NiTi

International Nuclear Information System (INIS)

Vaidyanathan, R.; Bourke, M.A.; Dunand, D.C.

1999-01-01

Neutron diffraction spectra were obtained during various stages of a reversible stress-induced austenite to martensite phase transformation in superelastic NiTi. This was accomplished by neutron diffraction measurements on bulk polycrystalline NiTi samples simultaneously subjected to mechanical loading. Analysis of the data was carried out using individual lattice plane (hkl) reflections as well as by Rietveld refinement. In the Rietveld procedure, strains in austenite were described in terms of an isotropic (hkl independent) and an anisotropic (hkl dependent) component. At higher stresses, austenite lattice plane reflections exhibited nonlinear and dissimilar elastic responses which may be attributed to the transformation. The texture evolution is significant in both austenite and martensite phases during the transformation and two approaches were used to describe this evolving texture, i.e., an ellipsoidal model due to March - Dollase and a generalized spherical-harmonic approach. The respective predictions of the phase fraction evolution as a function of applied stress were compared. A methodology is thus established to quantify the discrete phase strains, phase volume fractions, and texture during such transformations. copyright 1999 American Institute of Physics

Advanced functions using VBA for the Yacuiba Rio Grande (GASYRG) gas pipeline; Funcoes avancadas usando VBA no gasoduto Yacuiba Rio Grande

Energy Technology Data Exchange (ETDEWEB)

Torres Vega, Raul [TRANSIERRA S.A., Santa Cruz (Bolivia)

2005-07-01

The Yacuiba - Rio Grande Gas Pipeline is remote operated from the Supervision and Control Center (CSC) located in the offices of Transierra S.A. in Santa Cruz de la Sierra, Bolivia. This operation is made by means of a SCADA system based on satellite communication, it starts off at Yacuiba and finishes in Rio Grande, where it deliveries the export gas to Brazil. An Advanced Functions application was developed at the Transierra's CSC, This application runs under Intellution's iFix (HMI of the SCADA) in a Windows platform. It gathers transportation data in real time and by means of a mathematical process and a steady state simulation it makes the following on line calculations: Line Pack, Leak Detection, Transport Efficiency, Pressure Estimate in intermediate points and gas real velocity in the pipeline. The application was developed using Visual BASIC for Applications (VBA) (included in Intellution's iFix) and by means of an interphase to a historical server (iHistorian, Intellution) it is possible to store the obtained results, this integration also allows for the creation of graphs and trends with a great flexibility and to activate alarm points. With a practically null investment, this application replaces high cost specialized packages that are accessories to simulation or SCADA applications. (author)

Magnetic phase transitions in strongly chained semiconductor compounds TIFeS2 and TIFeSe2

International Nuclear Information System (INIS)

Asgerov, E.B.; Madadzada, A.I.; Beskropvniy, A.I.; Asgerov, E.B.; Mehdiyeva, R.N.; Madadzada, A.I.; Ismayilov, D.I.; Kerimova, E.M.

2014-01-01

Full text: The analysis of diffraction data was carried out by the Rietveld method using the programs VMRIA and FullProf, using as a starting model for the calculations of neutron diffraction profile of X-ray data. The neutron data showed that over the entire temperature range of these compounds have a monoclinic crystal structure symmetry

Bulletin of Materials Science | Indian Academy of Sciences

Indian Academy of Sciences (India)

We have studied for the first time the effect of Ag addition (0–15 wt%) to the superconducting system, Nd 1.85 Ce 0.15 CuO 4 , on its crystal structure and local structural features, using synchrotron X-ray diffraction(SXRD) and Raman spectroscopy, respectively. SXRD and subsequent Rietveld refinement studies on powders ...

Characterization of vaterite synthesized at various temperatures and stirring velocities without use of additives

Czech Academy of Sciences Publication Activity Database

Ševčík, Radek; Pérez-Estébanez, Marta; Viani, Alberto; Šašek, Petr; Mácová, Petra

2015-01-01

Roč. 284, November (2015), s. 265-271 ISSN 0032-5910 R&D Projects: GA ČR(CZ) GP14-20374P; GA MŠk(CZ) LO1219 Keywords : synthesis * vaterite * Rietveld method * morphology * nanoindentation Subject RIV: AL - Art, Architecture, Cultural Heritage Impact factor: 2.759, year: 2015 http://www.sciencedirect.com/science/article/pii/S0032591015005239

Structural behaviour of AgNO3 at low temperatures by neutron ...

Indian Academy of Sciences (India)

[4] F El-Kabbany, Y Badr, G Said and S Taha, Appl. Phys. A43, 65 (1987). [5] Z Shen, W F Sherman and G R Wilkinson, J. Mol. Struct. 175, 395 (1988). [6] R Rodriguez-Carvajal, FULLPROF: A Program for Rietveld Refinement, profile matching and integrated intensity, version 3.1 (LLB, France) (1995). [7] R Feyerherm, M F ...

Characterisation and development of fine porosity in magnesium potassium phosphate ceramics

Czech Academy of Sciences Publication Activity Database

Viani, Alberto; Radulescu, A.; Pérez-Estébanez, Marta

2015-01-01

Roč. 161, December (2015), s. 628-630 ISSN 0167-577X R&D Projects: GA MŠk(CZ) LO1219 Keywords : amorphous materials * chemically-bonded ceramics * microstructure * Rietveld-RIR method * small-angle neutron scattering * specific surface area Subject RIV: AL - Art, Architecture, Cultural Heritage Impact factor: 2.437, year: 2015 https://juser.fz-juelich.de/record/255737

Eficacia de programas de intervención para el desarrollo de habilidades psicológicas en jóvenes con discapacidad mental

Directory of Open Access Journals (Sweden)

Dalia Ma. Aguirre Pérez

2002-01-01

Full Text Available Se muestra el desempeño de personas adolescentes y adultas con daño cerebral, después de haber participado en programas de intervención para el desarrollo de habilidades psicológicas, que permitan promover su integración social e independencia personal. El estudio se llevó acabo aplicando la escala de Rogers y D?Eugenio, la evaluación psicológica breve en español (neuropsi y el test guestáltico visomotor de Bender.

Determinantes para la estructura de financiamiento de las empresas no financieras: un análisis con datos de panel para Ecuador 2004 y 2006

OpenAIRE

Ulloa Mendez, Carmen Isabel; Barrios Villon, Raquel Delcarmen

2008-01-01

La presente tesis hace referencia al análisis de los Determinantes para la Estructura de Financiamiento de las empresas ecuatorianas no financieras que cotizan en el mercado bursátil, aplicando la metodología de datos de panel para el periodo comprendido entre 2004 y 2006, para determinar, mediante un recorrido por la literatura teórica, empírica y la posterior aplicación descriptiva y econometrica, los factores explicativos del nivel de endeudamiento, los cuales manifestarán de forma impo...

Arquitectura para sistemas de memoria organizacional en instituciones de educación superior

OpenAIRE

Quilca Condori, Alexander Edwin

2014-01-01

El presente trabajo de investigación tiene como objetivo definir una arquitectura para sistemas de Memoria Organizacional en Instituciones de Educación Superior. El objetivo surge del problema identificado, en el cual la construcción de sistemas de gestión del conocimiento es tratada como construcción de sistemas típicos, aplicando métodos iterativos que si bien proporcionan versiones tempranas del sistema, no permiten predecir y gestionar adecuadamente el desarrollo del sistema. Además, d...

Análisis estructural de la gestión de la convivencia escolar en centros de buenas prácticas de Andalucía (España)

OpenAIRE

Tirado Morueta, Ramón; Conde Vélez, Sara

2016-01-01

Este artículo presenta un estudio cuyo objetivo es comprobar desde una perspectiva estructural la influencia de un conjunto de medidas en la reducción de problemas de convivencia. Se toma una muestra de centros con amplia experiencia en la gestión de la convivencia en Andalucía (España), aplicando escalas de medida sometidas a análisis de fiabilidad y validez de constructo. Los resultados permiten corroborar la influencia del liderazgo, la educación en el conflicto, la elabo...

Sistema agropecuario integrado usando labranza cero

OpenAIRE

Pedro Paneque Rondón

2003-01-01

En el trabajo se muestra una tecnología de punta con vistas a desarrollar la explotación de las actividades agrícolas y pecuarias en una misma finca, para la producción de granos, cahe y leche, simultáneamente de forma programada, aplicando la tecnología denominada "Integración Agricultura-Pecuaria", con el propósito de obtener mejor apro v echamiento de los bienes de producción, mano de obra, maquinaria, instalaciones y principalmente el suelo

Estudio para un Modelo de Gestión de un Acuífero Costero, mediante Metodologías Participativas y Análisis Geoestadístico en el marco del Desarrollo Local. Manglaralto, Ecuador

OpenAIRE

Herrera Franco, Gricelda América

2016-01-01

El presente estudio se fundamenta en la investigación-acción-participativa (IAP), para buscar alternativas que tiendan al desarrollo local de un territorio. Se centra en la cuenca hidrográfica del rio Manglaralto-Santa Elena-Ecuador, aplicando un sistema metodológico participativo que considera las características peculiares del territorio, que se analizan geoespacialmente reconociendo la influencia de la dinámica de sus cambios y observando los móviles que la propiciaban. A través de mecani...

Diseño y Construcción de un Electroimán Tipo Solenoide

OpenAIRE

Raúl Vargas Alba; Pedro Juárez Molina

2013-01-01

Se presenta el desarrollo de un p rototipo experimental aplicando los principios básicos de ele ctromagnetismo mediante la conceptualización de un electroimán simple con su correspondiente diseño, con éste se pretende propiciar que el estudiante de ingeniería en sistemas computacionales del Instituto Tecnológico de Querétaro que cursa el 2º semestre visualice los diversos orígenes de física clásica y una de sus aplicaciones.

Equilibrio entre fases para la aplicación de solventes verdes en tecnología de alimentos

OpenAIRE

Hernández, Elvis J.

2010-01-01

[ES]: En este trabajo se presentan los resultados obtenidos del estudio (experimental y teórico) del equilibrio entre fases de compuestos alimentarios y solventes verdes, aportando nuevos resultados a los fundamentos de los procesos de separación por contacto en equilibrio de la tecnología de alimentos. Se obtuvieron nuevos datos de equilibrio entre fases, aplicando métodos experimentales a altas presiones (equilibrio líquido – fluido supercrítico, para el disolvente dióxido de carbono) y ...

Aplicación de la metodología de intervención psicosocial de la Asociación de Expertos en Psicosociología Aplicada - AEPA en una empresa siderometalúrgica

OpenAIRE

López-Barón, Francisco; Carrión García, M. Ángeles

2014-01-01

Peer-reviewed Estudio de caso de la intervención psicosocial en una empresa siderometalúrgica aplicando la metodología de intervención psicosocial de la Asociación de Expertos enb Psicosociología Aplicada - AEPA. A case study of psycho-social intervention in an iron and steel company applying the methodology of psychosocial intervention of the Association of Applied Psychology Experts - AEPA. Estudi de cas de la intervenció psicosocial en una empresa siderometal·lúrgica aplicant la m...

¡Te lo creíste! Sobre cómo la información falsa se introduce en nuestra memoria

Directory of Open Access Journals (Sweden)

Malen Migueles

2008-11-01

Full Text Available La incorporación de información falsa en la memoria de un suceso delictivo puede alterar el subsiguiente testimonio. Para estudiar la aceptación de tres tipos diferentes de información falsa se realizaron tres experimentos aplicando el paradigma de la información engañosa. Los resultados señalan que los detalles (vs. acciones, los contenidos periféricos (vs. centrales y la información de tipicidad alta (vs. baja se aceptan con mayor facilidad.

Riesgo psicosocial de los trabajadores inmigrantes en España

OpenAIRE

Sanchis-Ruiz, A.; Varela-Hall, C.; Martins-Muñoz, G.; Díaz-Sotero, M.

2013-01-01

Introducción: España en las últimas décadas ha sido un receptor de un intenso flujo migratorio, sin embargo, por la crisis financiera actual, se está evidenciando un gran descenso. La inmigración está ligada al trabajo y búsqueda de mejores condiciones de vida. El trabajador inmigrante presenta una serie de riesgos psicosociales. Metodología: Se realiza búsqueda en principales bases de datos bibliográficas mediante palabras clave y se descriptores, aplicando posteriormente criterios de pertin...

Violencia de género y procesos de empobrecimiento: estudio de la violencia contra las mujeres por parte de su pareja o ex-pareja sentimental

OpenAIRE

Espinar-Ruiz, Eva

2003-01-01

El objetivo de esta investigación ha sido analizar las posibles relaciones entre la violencia de la que puede ser objeto una mujer por parte de su pareja o ex-pareja sentimental y diferentes procesos de empobrecimiento. Para ello, aplicando un enfoque de género, se atiende a dos perspectivas: los procesos de empobrecimiento como contexto en el que pueden tener lugar situaciones de violencia y la propia violencia como factor de empobrecimiento. La estrategia metodológica seguida es básic...

Videojuegos en redes sociales: aprender desde experiencias óptimas

OpenAIRE

Esnaola Horacek, Graciela; Levis, Diego

2009-01-01

Desarrollaremos conceptos de interés académico acerca de las posibilidades educativas que actualmente ofrecen los entornos lúdicos en la Web 2.0, capturando el interés generalizado de los estudiantes. Destacaremos una definición particular de videojuego aplicando determinadas categorías de análisis a las propuestas lúdicas que ofrecen las redes sociales, en especial el caso Facebook. La línea que destacamos durante nuestra trayectoria de investigación se ubica en los entrecruzamientos que ...

Análisis multivariado y QFD como herramientas para escuchar la voz del cliente y mejorar la calidad del servicio

OpenAIRE

Gutiérrez Pulido,Humberto; Gutiérrez González,Porfirio; Garibay López,Cecilia; Díaz Caldera,Lizbeth

2014-01-01

Las organizaciones del sector servicios contribuyen con un alto porcentaje del producto interno bruto de las principales economías del mundo, esto genera la necesidad de buscar alternativas para mejorar los procesos de este sector. Es reconocido que escuchar la voz del cliente es un buen punto de partida para evaluar la calidad de un servicio. Es frecuente que se busque escuchar al cliente aplicando algún cuestionario o encuestas. Sin embargo, debido a los múltiples ítems de las encuestas, es...

DETECCION Y RECONOCIMIENTO DE ROSTROS

OpenAIRE

Tinoco Martínez, Sergio Rogelio

2012-01-01

En el presente trabajo se revisa el algoritmo propuesto por Moghaddam et al. en [Moghaddam95a] para la detección automática de rostros y para el proceso complementario de reconocimiento facial en [Moghaddam96]. Aunque no se proporciona una aportación nueva se pudo comprobar en una implementación propia, aplicando varias simplificaciones al desarrollo original de Moghaddam, el desempeño reportado en cuanto al reconocimiento facial se trata. Sin embargo, en cuanto a la combinación de detecci...

Propuesta de implementación de una guía de procedimientos para mejorar la eficiencia en los procesos de la Central de Esterilización del Hospital "Dr. Teodoro Maldonado Carbo" de la ciudad de Guayaquil.

OpenAIRE

Payez Freire, Eva Cristina

2015-01-01

La presente investigación se desarrolló en la central de esterilización del Hospital Teodoro Maldonado Carbo de la ciudad de Guayaquil, perteneciente al Instituto Ecuatoriano de Seguridad Social, con la finalidad de evaluar el nivel de aplicación de los procedimientos obligatorios de esterilización y su relación con el nivel de eficiencia en los resultados obtenidos. Para el logro de los objetivos planteados se desarrolló una investigación de campo aplicando encuestas y entrevistas al...

Estudio de viabilidad de financiamiento a través de un contrato forward de tasas de interés en Empresas del Sector Industrial - metálico en el Ecuador

OpenAIRE

Aguayo Yépez, Andrés Gustavo

2007-01-01

El presente estudio; orientado a determinar la viabilidad de obtener financiamiento utilizando un mecanismo alterno de endeudamiento a través de contratos derivados, y específicamente aplicando y suscribiendo un “Contrato forward de tasas de interés” (FRA). En cada uno de los fundamentos planteados en el estudio de investigación se ha enfatizado en aspectos tanto de forma como de fondo, esto es, determinando claramente el sector al cual esta dirigido, los participantes en el mercado, las c...

A vueltas con la alfabetización visual: lenguaje y significado en las películas de Wes Anderson

OpenAIRE

Ferreras Rodríguez, José Gabriel; Leite, Lucimeire Virgilio

2008-01-01

El presente artículo tiene por objetivo discutir algunos elementos del concepto de la alfabetización visual, aplicando, luego, las herramientas de análisis de imágenes a las películas de Wes Anderson, como ejemplos del manejo intencional de las imágenes para transmitir determinados significados. The present article aims to discuss, firstly, some elements encompassed in the definition of visual literary and, secondly, to apply some image analysis tools to Wes Anderson’s movies, as examples ...

A vueltas con la alfabetización visual: lenguaje y significado en las películas de Wes Anderson

OpenAIRE

José Gabriel Ferreras Rodríguez; Lucimeire Vergilio Leite

2008-01-01

El presente artículo tiene por objetivo discutir algunos elementos del concepto de la alfabetización visual, aplicando, luego, las herramientas de análisis de imágenes a las películas de Wes Anderson, como ejemplos del manejo intencional de las imágenes para transmitir determinados significados. The present article aims to discuss, firstly, some elements encompassed in the definition of visual literary and, secondly, to apply some image analysis tools to Wes Anderson’s movies, as examples of...

Evaluación de los contenidos de información de medicamentos en un grupo de agencias reguladoras de medicamentos

OpenAIRE

Gil Rojas, Yaneth

2016-01-01

OBJETIVO: Evaluar las diferencias de información publicada por el Invima y otras Autoridades Reguladoras de Medicamentos en relación a un grupo de variables seleccionadas y analizar las diferencias aplicando estrategias de visualización de datos. METODOLOGÍA: Estudio descriptivo de corte transversal, en el cual se comparan las diferencias en la información de medicamentos publicada en las agencias reguladoras de medicamentos. Para la definición de los criterios de comparación, más relevantes ...

Efecto de extractos vegetales de polygonum hydropiperoides, solanum nigrum y calliandra pittieri sobre el gusano cogollero (spodoptera frugiperda)

OpenAIRE

Lizarazo H., Karol; Mendoza F., Cristina; Carrero S., Rocío

2009-01-01

El gusano cogollero Spodoptera frugiperda es una de las plagas que más afectan los cultivos en la región de Sumapaz (Cundinamarca, Colombia). En la actualidad se controla principalmente aplicando productos de síntesis química, sin embargo la aplicación de extractos vegetales surge como una alternativa de menor impacto sobre el ambiente. Este control se emplea debido a que las plantas contienen metabolitos secundarios que pueden inhibir el desarrollo de los insectos. Por tal motivo, la present...

Clima y compromiso organizacional en una mediana empresa manufacturera de San Luis Potosí, S.L.P.

OpenAIRE

Crespo Bravo, Carolina

2016-01-01

Este trabajo tiene como objetivo principal analizar la relación que existe entre clima y compromiso organizacional y de estos con las características personales. La muestra se integró con 80 trabajadores de una mediana empresa manufacturera ubicada en la ciudad de San Luis Potosí. Se realizó un estudio empírico transversal aplicando cuestionarios para clima organizacional de Araujo et al. (2011), el cual se construyó con características inherentes a las dimensiones: a) estilo de geren...

Sistemas de Recomendaciones: Una herramienta para mejorar la gestión de la información en las PYMES

Directory of Open Access Journals (Sweden)

Gladys Patricia Guevara Albán

2018-02-01

Full Text Available La aparición de los sitios web, el crecimiento de las redes sociales, la búsqueda de formas más eficiente de recaudar información y analizarlas para la toma decisiones en tiempo real y la forma de como las personas se agrupan y planean consumir productos y/o servicios como parte de una actividad conjunta nacen los sistemas de recomendadores (SR siendo este objeto de nuestro estudio y cuyo objetivo principal es incrementar el nivel de confianza en la gestión de la información y la toma de decisiones en las PYMES aplicando SR. La línea de investigación en recomendadores, que se encuentra actualmente en auge, sufre una serie de de ciencias, radicadas en un incorrecto modelado de los comportamientos sociales de los usuarios, que reducen su e ciencia. El presente estudio es de tipo documental, descriptivo y de campo. En cuanto a las técnicas se aplicó revisión documental, cuestionario y la entrevista para así tener una noción global del espectro de estudio. En cuanto a los resultados obtenidos, microempresarios que son objeto de este estudio manifestaron la necesidad de disponer de un sitio que mejore la búsqueda ordenada de información por recomendaciones aplicando un modelo de búsqueda específico mejorado el proceso de la toma de decisiones y los servicios al cliente.

APLICACIÓN DE UN MODELO ARIMA PARA PRONOSTICAR LA PRODUCCIÓN DE LECHE DE BOVINO EN BAJA CALIFORNIA, MÉXICO

Directory of Open Access Journals (Sweden)

Eduardo Sánchez

2013-11-01

Full Text Available El objetivo fue aplicar un modelo de series de tiempo univariado tipo ARIMA en la descripción y pronóstico del comportamiento de la producción lechera de bovino en el estado, aplicando para ello la metodología de Box y Jenkins. La serie de producción mensual de litros leche de enero del 2000 a diciembre del 2009 fue utilizada en el estudio. El análisis  del  correlograma  y la aplicación de la prueba de Dickey y Fuller aumentada indicaron que la producción lechera presentaba un comportamiento estacional. Del análisis de diversas combinaciones AR(p y MA(q, dos modelos fueron propuestos y evaluados: ARMA (1,1 y ARMA (2,2. Los parámetros fueron estimados por mínimos cuadrados. Con base a éstos y aplicando los criterios de Akaike y Schwarz (18.06, 18.13 y 18.20, 18.27, respectivamente se definió el mejor modelo. Adicionalmente se analizaron los residuales y la capacidad predictiva de cada modelo a través de los estadísticos de calidad de ajuste, resultando como mejor el ARMA (1,1. Se concluye que este tipo de modelos son de utilidad tanto para describir como para predecir el comportamiento de la producción lechera.

Direct observations of the MOF (UiO-66) structure by transmission electron microscopy

KAUST Repository

Zhu, Liangkui

2013-01-01

As a demonstration of ab initio structure characterizations of nano metal organic framework (MOF) crystals by high resolution transmission electron microscopy (HRTEM) and electron diffraction tomography methods, a Zr-MOF (UiO-66) structure was determined and further confirmed by Rietveld refinements of powder X-ray diffraction. HRTEM gave direct imaging of the channels. © 2013 The Royal Society of Chemistry.

Incident spectrum determination for time-of-flight neutron powder diffraction data analysis

International Nuclear Information System (INIS)

Hodges, J. P.

1998-01-01

Accurate characterization of the incident neutron spectrum is an important requirement for precise Rietveld analysis of time-of-flight powder neutron diffraction data. Without an accurate incident spectrum the calculated model for the measured relative intensities of individual Bragg reflections will possess systematic errors. We describe a method for obtaining an accurate numerical incident spectrum using data from a transmitted beam monitor

Neutron scattering study of combustion-synthesized Ce1− xCuxO2− x

Indian Academy of Sciences (India)

Powder neutron diffraction and Hi- neutron diffraction data have been recorded and analysed in order to obtain the local and long range order of Cu in Cu-doped CeO2 with three doping levels of Cu. Rietveld method and MCGR techniques of data analysis for the two types of data reveal that the Cu ion is in the 2+ ...

Structural and spectroscopic investigation of lanthanum-substituted ...

Indian Academy of Sciences (India)

Administrator

and one Y atom form two alternated equilateral triangles at level 1/4 and 3/4 centred on ..... Carpena et al observed that the localization of Nd. 3+ ions in the cationic sites depended ... Atomic coordinates, occupancy factors and thermal parameters after Rietveld refinement of Sr10–xLax(PO4)6–x. (SiO4)xO samples. Wyckoff.

Efecto de la fisioterapia en un paciente con cuadriplejia por ependimoma medular

Directory of Open Access Journals (Sweden)

Julio César Granados-Carrera

2014-07-01

Full Text Available La fisioterapia en pacientes con problemas neurológicos, mejora la capacidad funcional identificando limitaciones provocadas por la lesión aplicando técnicas kinésicas. Se describe los efectos de la fisioterapia en un paciente con cuadriplejía secundaria a ependimoma medular que no recibió tratamiento quirúrgico. La regulación del tono postural favoreció el control postural y el equilibrio en actividades en sedente y en cama. Se obtuvo independencia funcional en actividades básicas de la vida diaria.

Implementación de miniproyectos de investigación: una forma no convencional en los trabajos prácticos de práctica profesional bioquímica

OpenAIRE

Pawluk, Diana Beatriz

2013-01-01

En la presente tesis, se implementó y evaluó un trabajo práctico innovador, no estructurado, mediante el desarrollo de pequeños proyectos de investigación o “miniproyectos” con finales abiertos, aplicando técnicas de Biología Molecular. Se evaluó el impacto sobre las actitudes que experimentaron los alumnos al realizar una actividad práctica tradicional (Grupo Control), en comparación con la de aquellos que hicieron una actividad práctica no estructurada (Grupo Ensayo), de la Sección Parasi...

Interface Móvil para el Sitio Web de la UACO

Directory of Open Access Journals (Sweden)

Agustin Moyano

2016-04-01

En este trabajo nos enfocamos en desarrollar un prototipo para el sitio Web móvil de la Unidad Académica Caleta Olivia (UACO de la Universidad Nacional de la Patagonia Austral (UNPA considerando al usuario como el centro del diseño y desarrollo. Con esta filosofía en mente, se define un marco de trabajo para el desarrollo del prototipo incorporando recomendaciones de Usabilidad y Accesibilidad Web de referentes internacionales y aplicando herramientas para el diseño inclusivo dirigido a dispositivos móviles.

Factores de éxito de las alianzas estratégicas: el caso de las empresas integradoras mexicanas

Directory of Open Access Journals (Sweden)

Francisco Camargo Mireles, Ph.D

2011-07-01

Full Text Available El propósito de este trabajo fue explorar los factores de desempeño en las empresas integradoras mexicanas (una forma de alianza estratégica, aplicando un modelo teórico integral derivado de una revisión exhaustiva de la literatura del periodo 1985-2010. Los resultados obtenidos muestran que el desempeño de las alianzas está en función de dos actores: el socio y la alianza, y que cada uno de ellos tiene sus propios factores determinantes.

Evaluación de la modificación del contenido de nitrógeno en una fórmula de fertirriego usada en el cultivo de miniclavel variedad Rony cultivado en sustrato

OpenAIRE

Casas Ortiz, Nathalia Rocío

2015-01-01

El sector floricultor ocupa un lugar privilegiado en la economía colombiana. En la Sabana de Bogotá se encuentra aproximadamente el 85% del total del área cultivada por flores en nuestro país. El nivel de producción de flores se caracteriza por presentar altos consumos de agua. Esta actividad tiene un gran impacto sobre el ambiente y los costos de producción del cultivo, en especial, cuando las labores de fertirriego se realizan de manera convencional, aplicando dosis de fertirriego uniformes...

Modelo de simulación dinámica para la evaluación de la viabilidad financiera de un negocio y la estimación de su probabilidad de éxito

OpenAIRE

Robert Hernández Martínez

2013-01-01

Un problema típico que enfrentan los pequeños negocios es estimar - con razonable probabilidad – si su empresa tendrá éxito o no. El presente modelo computacional permite evaluar el riesgo de invertir en un proyecto de negocio; aplicando herramientas financieras, estadísticas y de simulación, para responder a preguntas de interés para el futuro emprendedor de un negocio.El modelo está diseñado para solicitar algunos datos de entrada (INPUTS), información clave para procesar el análisis de via...

ABSTRACT IMPLEMENTATION OF A KIND TO MANAGE DATA SETS USING PROGRAMMING LANGUAGE C + +

OpenAIRE

Ruiz L., Edgar; Hinojosa L., Hilmar

2014-01-01

This article presents the implementation of a data abstract type to represent the Set Theory Mathematical Concept, The program has been written in C++ Program Language applying the Object Oriented Programming Paradigm through a Dev C++ v.4.1 Compiler, a GNU compiler with GPL licence. El artículo presenta la implementación de un tipo abstracto de datos para representar el concepto matemático de la teoría de conjuntos. El programa ha sido escrito en lenguaje de programación C++ aplicando el ...

APLICACIÓN DE INGENIERÍA DIRIGIDA POR MODELOS (MDA, PARA LA CONSTRUCCIÓN DE UNA HERRAMIENTA DE MODELADO DE DOMINIO ESPECÍFICO (DSM Y LA CREACIÓN DE MÓDULOS EN SISTEMAS DE GESTIÓN DE APRENDIZAJE (LMS INDEPENDIENTES DE LA PLATAFORMA

Directory of Open Access Journals (Sweden)

CARLOS ENRIQUE MONTENEGRO MARÍN

2011-01-01

Full Text Available El objetivo general es realizar un modelado específico de dominio para la construcción de módulos en sistemas de gestión del aprendizaje (LMS independientes de la plataforma. Para esto, el punto de partida es un metamodelo para la construcción de un lenguaje específico de dominio (DSL que con ingeniería dirigida por modelos (MDE y aplicando las debidas transformaciones se consiga de un modelo independiente de la plataforma, el despliegue de este modelo se realizara en varias plataformas LMSs.

Los Mapas Contables de Gestión de las Empresas Cotizadas Chilenas: Análisis Cualitativo

OpenAIRE

Pérez-Benedito, Miguel A; Porcuna-Enguix, Luis; Porcuna-Enguix, Rubén

2017-01-01

El artículo analiza las clases de gestión realizadas por las empresas cotizadas chilenas localizadas en los espacios administrativos de Chile. La orientación del análisis realizado considera que el factor cultural de la región donde están localizadas las empresas chilenas condiciona la clase de gestión desarrollada por dichas empresas. El desarrollo de esta hipótesis se realiza aplicando la metodología contable de los gráficos radiales. Las tensiones existentes entre los periodos medios de ma...

Progreso Técnico y Poder de Mercado en la Industria Textil: Evidencia Empírica para Colombia, 1975-2006

OpenAIRE

José B. Gallego-Alzate; Jaime A. Osorio-Usuga; Juan D. Lora-Restrepo

2011-01-01

Este trabajo presenta los resultados de un estudio relacionado con la existencia de poder de mercado en la industria textil colombiana desde 1975 hasta 2006. Se utiliza como indicador de poder de mercado el índice de Lerner, obtenido a partir de la generalización del residuo de Solow. La estimación se realiza utilizando series de tiempo obtenidas de la Encuesta Anual Manufacturera y aplicando el método de los mínimos cuadrados ordinarios. La conclusión fundamental es la confirmación de la exi...

Las nuevas tecnologías : un enfoque real sobre su aplicación en la creación de comunidades virtuales basadas en la fidelización de clientes a través de estrategias de venta personalizada

OpenAIRE

Cutropía Fernández, Carlo

2002-01-01

Esta tesis doctoral tiene una finalidad no sólo teórica, de investigación relativa a estrategias de venta personalizada mediante la creación de comunidades virtuales aplicando para ello nuevas tecnologías, sino también práctica, puesto que los resultados de la citada investigación se han desarrollado de hecho y están funcionando con éxito en una comunidad virtual de aproximadamente dieciséis mil personas y el presente trabajose ocupa de presentar y analizar dichos resultados. Este doble enfoq...

La vegetación del peñón de Gibraltar

OpenAIRE

Sánchez García, Iñigo; Galán de Mera, Antonio; Cortés, John E.

2000-01-01

La vegetación del Peñón de Gibraltar. En el presente trabajo, presentamos un estudio de la vegetación de Gibraltar según la metodología de Braun-Blanquet. Como resultado, proponemos los nuevos sintáxones que aparecen en el resumen en inglés. La principal característica del paisaje vegetal de Gibraltar es que la vegetación natural está muy alterada con la presencia de comunidades fragmentarias. Estas son comentadas aplicando los conceptos de 'comunidad basal' (BC), 'comunidad derivada' (DC) y ...

Estrategias para la competitividad en la agroexportación de alcachofa

OpenAIRE

Fernández J., Leoncio; Facultad de Economía y Planificación, Universidad Nacional Agraria La Molina (Perú).

2009-01-01

Esta investigación tuvo como objetivo definir la estrategias para la competitividad en la agroexportación de alcachofa, aplicando para ello el modelo de Michael porter referida a las estrategias genéricas o generales; pero complementando el análisis con el modelo de Cliff Bowman, que sitúa mas apropiadamente en el entorno la definición de la estrategia. El resultado fue definir el “liderazgo en costos” como estrategia para la competitividad, complementado con una estrategia de diferenciación....

Aumento do Acesso à Internet em Banda Larga no Brasil e Sua Possível Relação com o Crescimento Econômico: Uma Análise de Dados em Painel

OpenAIRE

Hildebrando Rodrigues Macedo; Alexandre Xavier Ywata de Carvalho

2010-01-01

Aplicando-se modelos econométricos sobre dados em painel, analisou-se o possível relacionamento entre aumento da densidade de acessos de banda larga por habitantes no Brasil e o crescimento do Produto Interno Bruto (PIB) e PIB per capita. Utilizaram-se dados, desagregados por Unidades da Federação (UFs), das densidades de acessos de banda larga, PIB, PIB per capita e escolaridade da população, e dados agregados nacionalmente dos investimentos em telecomunicações. Os dados de densidade de aces...

ANÁLISIS COMPARATIVO DE FRAMEWORKS PARA EL DESARROLLO DE APLICACIONES WEB EN JAVA

OpenAIRE

Sánchez Acosta, Carlos; Universidad Señor de Sipán; Tuesta Monteza, Victor; Universidad Señor de Sipán; Mejía Cabrera, Iván

2015-01-01

En éste documento se presenta un análisis comparativo de frameworks en Java para el desarrollo de aplicaciones web, aplicando una matriz de un modelo de evaluación. Para analizar los frameworks y seleccionarlos se realizó en base a criterios de madurez y documentación, obteniendo como resultado los Frameworks Spring, Struts, JSF, Angular JS para su evaluación.  Asimismo para el análisis teórico de frameworks se formuló un método QSOS, concebido para definir características comparativas del so...

Efecto de la adición de carragenina kappa i.ii y goma tara sobre características de calidad del jamón de cerdo picado y cocido.

OpenAIRE

Restrepo Molina, Diego Alonso; Molina Cote, Fabio Alexander; Cabrera Torres, Kenneth Roy

2011-01-01

Se evaluaron sinéresis, color y dureza instrumental y, sensorialmente las características de olor, sabor, color y dureza en jamones inyectados, cocidos y picados de cerdo, los cuales se habían elaborado aplicando en la salmuera de inyección una mezcla de hidrocoloides compuesta por carragenina kappa I.II y goma tara en una proporción de 79:21, en niveles del 1% y 1,2%, usando tres repeticiones para el estudio. Los jamones así elaborados se compararon contra un jamón testigo, elaborado sin el ...

EFECTO DE LA ADICIÓN DE CARRAGENINA KAPPA I.II Y GOMA TARA SOBRE CARACTERÍSTICAS DE CALIDAD DEL JAMÓN DE CERDO PICADO Y COCIDO EFFECT OF THE ADDITION OF KAPPA I.II CARRAGEENAN AND TARA GUM ON QUALITY CHARACTERISTICS OF COOKED AND CHOPPED PORK HAMS

OpenAIRE

Diego Alonso Restrepo Molina; Fabio Alexander Molina Cote; Kenneth Roy Cabrera Torres

2010-01-01

Se evaluaron sinéresis, color y dureza instrumental y, sensorialmente las características de olor, sabor, color y dureza en jamones inyectados, cocidos y picados de cerdo, los cuales se habían elaborado aplicando en la salmuera de inyección una mezcla de hidrocoloides compuesta por carragenina kappa I.II y goma tara en una proporción de 79:21, en niveles del 1% y 1,2%, usando tres repeticiones para el estudio. Los jamones así elaborados se compararon contra un jamón testigo, elaborado sin el ...

An exploratory study regarding the hypothetical human embryo donation in Peru

OpenAIRE

Álvarez Díaz, Jorge Alberto

2013-01-01

Objetivo: Explorar opiniones de pacientes que han acudido a técnicas de reproducción asistida (TRA) complejas, respecto a la donación de gametos y embriones, así como las razones para hacerlo o no. Diseño: Estudio transversal de bioética descriptiva, con metodología cualitativa etnográfica, mediante entrevista semiestructurada, aplicando análisis del discurso al texto resultante. Lugar: Clínica privada, en Lima, Perú. Participantes: Veinte mujeres y 12 hombres, quienes habían acudido por lo m...

Influencia de la asimetría de información de mercado en el nivel de ventas de los productores de aguaymanto distrito, Bambamarca, 2013 - 2015

OpenAIRE

Vásquez Montenegro, Ellard Eric

2017-01-01

La presente investigación desarrollada trata de determinar ¿Cuál es la Influencia de la asimetría de información de mercado en el nivel de ventas del aguaymanto (Phisalis peruviana L.) en productores? del Distrito de Bambamarca, específicamente en los caseríos de Lucmacucho, Cashapampa Bajo y Alto, Nogalpampa y Hualanga pertenecientes al Centro Poblado de Llaucan. El método que se utilizó para resolverlo es el método científico, aplicando la encuesta por tratarse de una ciencia social, con la...

Articulación de la participación ciudadana y de las autoridades del cantón Puebloviejo (Prov. De los Ríos) en la gestión del manejo integral de los residuos sólidos, en función del desarrollo local.

OpenAIRE

Quinaloa Sisa, Darwin Michael

2015-01-01

La presente investigación cuyo enfoque orienta a demostrar mediante una adecuada gestión de residuos, aplicando como herramienta de acción el reciclaje. La problemática medio-ambiental en lo relacionado a los RSU en las comunidades pequeñas tiene varios grados de complejidad articular con la comunidad. Otro aspecto importante es el mejoramiento de la calidad de vida mediante la generación de puestos de trabajo y por consiguiente obtención de beneficios económicos. This research approach...

Optimización del desempeño de un sistema de recomendación de documentos de texto basado en la configuración de los servidores.

OpenAIRE

Rodrigo Vences Nava; Víctor Hugo Menéndez Domínguez; Alfredo Zapata González

2016-01-01

Cuando se habla de sistemas informáticos en la Web, una de las configuraciones más utilizadas por los desarrolladores es la combinación de Apache y MySql, independientemente del sistema operativo sobre el cuál se desarrolle. En este trabajo se muestra cómo optimizar los tiempos de procesamiento y despliegue de información en el navegador Web de un Sistema de Recomendación de trabajos de titulación, aplicando sencillas configuraciones en el servidor Apache y siguiendo algunas buenas prácticas ...

El nexo entre cambio climático y energía renovable en el Mercosur. Un análisis comparativo de las legislaciones de Argentina y Brasil

OpenAIRE

Casola, Laura; Freier, Alexander

2017-01-01

El sector energético es uno de los principales contribuyentes al cambio climático debido a la combustión de hidrocarburos, por lo que la energía renovable se presenta como una alternativa para promover el desarrollo sustentable. En ese sentido, aplicando una metodología comparativa, este artículo analiza las regulaciones sobre cambio climático y energía renovable en Argentina y Brasil, considerados los dos Estados política y económicamente más fuertes del Mercosur, los cuales están especialme...

Aplicación de la Teoría de Restricciones y su Incidencia en los Costos de Producción en la Empresa MIVIRN, de la ciudad de Riobamba provincia de Chimborazo.

OpenAIRE

Guananga Díaz, Freddy Román

2017-01-01

El presente proyecto de investigación tuvo como objetivo la elaboración una propuesta de mejora para la empresa MIVIRN aplicando la Metodología de la Teoría de Restricciones (TOC), para minimizar los costos de producción. En el desarrollo de la investigación se logra establecer la demanda histórica y en base a esta se proyecta la demanda futura, que permite evaluar y determinar los tiempos estándar, se costea los centros de producción mediante el costeo directo, con estos ...

Responsabilidad civil por accidentes en espectáculos taurinos

OpenAIRE

Caballero Moreno, María Araceli

2016-01-01

El trabajo versa sobre la responsabilidad civil aplicada al campo de los espectáculos taurinos, explicando el régimen de responsabilidad aplicable, regulado en el art. 1.902 de nuestro Código Civil, centrándose especialmente en quién debe asumir la responsabilidad en caso de producirse daños a los espectadores del festejo por los propios animales, si la propia víctima por haber llevado a cabo una conducta imprudente aplicando la teoría de la asunción del riesgo o los organizadores del festejo...

Aplicación de la metodología de solución de problemas para aumentar la productividad en una empresa textil

OpenAIRE

Paredes Sánchez, Luis Carlos; Paredes Sánchez, Luis Carlos

2014-01-01

El objetivo del presente informe de suficiencia profesional es presentar la mejora de la productividad en una empresa textil dedicada a la fabricación de cierres aplicando los conceptos de mejora continúa representados en la metodología de solución de problemas los cuales son utilizados en los círculos de calidad. Se inició con un diagnostico funcional de la empresa para conocer sus principales clientes, proveedores y procesos. Después se continuó con la descripción de su pensamiento estra...

Un marco de trabajo para la Integración de Arquitecturas de Software con Metodologías Ágiles de Desarrollo

OpenAIRE

Vivas, Luis; Cambarieri, Mauro; García Martínez, Nicolás; Petroff, Marcelo; Muñoz Abbate, Horacio

2013-01-01

La construcción de software dentro de un marco metodológico ágil ofrece la posibilidad de contar con procesos livianos y simples, aplicando técnicas de programación que permiten expresar el concepto de agilidad, garantizando código de calidad desde el inicio del proceso de desarrollo. Algunas técnicas que han sido probadas en metodologías tradicionales de desarrollo de software son usualmente utilizadas en metodologías ágiles, como por ejemplo las pruebas de unidad. En este trabajo propone...

Factores de contaminación ambiental por el desarrollo de proyectos petroleros en el Caño el Ingeniero, municipio de Puerto Gaitán Meta

OpenAIRE

Martínez Gómez, Sonia Janneth

2017-01-01

Tesis (Maestría en Desarrollo Sostenible y Medio Ambiente). Universidad de Manizales. Facultad de Ciencias Contables, Económicas y Administrativas. CIMAD, 2016 Con esta investigación se quiere realizar un estudio en el caño el ingeniero para determinar los principales factores y causas de contaminación, aplicando métodos de recolección de muestras para análisis y/o determinación de los valores de las fuentes de agua y posteriormente obtener unos resultados para realizar un análisis de lo q...

MODELOS REALISTAS EN LA VERIFICACIÓN DEL ESFUERZO CORTANTE EN ELEMENTOS DE HORMIGÓN ARMADO

Directory of Open Access Journals (Sweden)

Francisco Aguirre

2015-07-01

En este artículo se proponen modelos basados en la TCCM y TCCMS y se muestra resultados de ejemplos aplicando estos modelos comparándolos con las normas ACI 318-11 y CAN23.3-04. En el cálculo de la armadura transversal, la variación entre la TCCM y las normas ACI 318-11 y CAN23.3-04 fue de 33% y 64% respectivamente y la variación entre la TCCMS y las normas ACI 318-11 y CAN23.3-04 fue de 2% y 25% respectivamente.

Autoría de aplicaciones móviles para el análisis de datos

OpenAIRE

Person Montero, Tatiana

2018-01-01

La incorporación de aplicaciones móviles en diversos entornos genera una gran cantidad de información resultante de la interacción de los usuarios con estas aplicaciones. El análisis de esta información puede ser de gran utilidad para el profesional, ya que le puede facilitar la toma de decisiones o la valoración del proceso que esté aplicando, permitiendo mejorar los resultados o detectar determinados patrones. La información recogida se puede definir siguiendo una serie de características: ...

Marketing relacional en el sistema financiero español

OpenAIRE

Casariego Mogo, Diego

2013-01-01

Por lo tanto, nos planteamos en este trabajo conocer cómo un entorno de crisis económica ha afectado a las empresas bancarias en cuanto a sus políticas de marketing de relaciones, tratando de relacionar la situación económica de la entidad con sus estrategias de marketing relacional a través de análisis de casos concretos. Además, presentaremos una aproximación empírica que nos permita determinar aquellas entidades que están aplicando un mayor enfoque relacional.

COSTES SANITARIOS DIRECTOS DE LAS NEOPLASIAS DE PULMÓN Y VEJIGA DE ORIGEN LABORAL EN ESPAÑA EN 2008

OpenAIRE

Montserrat García Gómez; Rosa Urbanos Garrido; Rosario Castañeda López; Patricia López Menduiña

2012-01-01

Fundamentos: La falta de reconocimiento del origen laboral de algunos tumores malignos conlleva que el coste de su asistencia sanitaria recaiga sobre el Sistema Nacional de Salud. El objetivo de nuestro estudio es conocer el número de procesos atendidos por cáncer de pulmón y vejiga atribuibles al trabajo en España en el Sistema Nacional de Salud (SNS) en 2008, así como los costes sanitarios derivados de su atención. Métodos: El número de procesos se estimó aplicando las fracciones atribuible...

Generación de políticas para la gestión de riesgos de seguridad en el desarrollo de software.

OpenAIRE

Montalvo Armijos, Renny Geovanny

2017-01-01

El objetivo fue generar políticas para la gestión de riesgos de seguridad en el desarrollo de software en el Consejo de la Judicatura, la investigación empieza al generar un ambiente de pruebas en el que se encuentran configurados en el mismo servidor dos aplicaciones prototipo, los mismos que se configuran, una aplicando las políticas generadas, y otra sin aplicar las políticas. Como resultado de la investigación, al aplicar las políticas y utilizarlas durante la etapa de desa...

Demostraciones algebraicas de las ecuaciones cuadráticas en SHARḤ AL-URJŪZA AL-YĀSMĪNIYYA de IBN AL-HĀ'IM

OpenAIRE

Fadil, Abdelaziz; Puig, Luis

2014-01-01

El álgebra árabe es operar con cantidades desconocidas aplicando las mismas reglas aritméticas que operan con los números conocidos. Esta conceptualización, junto con la definición de las especies de números, ha facilitado el desarrollo del cálculo algebraico de las expresiones algebraicas. En particular, ha permitido la denominación, enunciación, clasificación y formulación de seis ecuaciones cuadráticas. Se han propuesto demostraciones ingenuas, geométricas y algebraicas de lo...

Deficiencia de Vitamina A y Estado Nutricional Antropométrico en niños MarginalesUrbanos y Rurales en el Estado Zulia, Venezuela

OpenAIRE

Amaya-Castellanos, Daisy; Viloria-Castejón, Haydée; Ortega, Pablo; Gómez, Gisela; Urrieta, Jesús R; Lobo, Pablo; Estévez, Jesús

2002-01-01

El presente estudio transversal fue realizado para estimar la prevalencia de deficiencia de vitamina A (DVA) y desnutrición proteico-energética en una población infantil (24 a 85 meses) de tres barrios marginales urbanos de Maracaibo Estado Zulia, Venezuela (n=173) y de una zona rural (n=34), vecina a Maracaibo, por medio del análisis del retinol sérico y mediciones antropométricas, aplicando puntuación Z a los indicadores Talla//Edad (ZT//E); Peso//Edad (ZP//E) y Peso//Talla (ZP//T), compara...

Tipos de redes personales de los inmigrantes y adaptación psicológica

OpenAIRE

Maya Jariego, Isidro

2002-01-01

Elaboramos una tipología de redes de apoyo en un colectivo de inmigrantes marroquíes (n=81), filipinos (n=69) y senegaleses (n=23) residentes en Marbella, aplicando la entrevista Mannheim de apoyo social (MISS) (Veiel, 1990, 1993). Primero realizamos tres análisis de conglomerados exploratorios utilizando como variables-criterio indicadores de (1) composición familiar y étnica, (2) funciones de apoyo, y (3) tamaño y estructura de la red. Los análisis de chi-cuadrado entre las tres clasificaci...

Biblioteca 2.0, nuevas estrategias de comunicación y marketing : el caso de la Biblioteca Universitaria de Huelva

OpenAIRE

Carvajal Cantero, María de los Ángeles; Escribano Loza, Juan Manuel; Gómez Boullosa, Juan José; González Parra, Inmaculada; Lara Díaz, Isabel; Moyar Godino, Lourdes; Ruiz Fernández, Mar; Yuste Álvarez, José Manuel

2013-01-01

La Biblioteca Universitaria de Huelva apuesta por ser una biblioteca 2.0. Aplica sus herramientas y filosofía para mejorar la comunicación con sus usuarios, conocer sus necesidades de información, difundir sus servicios y recursos y mejorar su visibilidad aplicando técnicas de marketing y branding. La BUH está presente en Facebook, Twitter, Tuenti y Flickr, además de tener dos blogs, uno interno (Oberón), y otro abierto (La Buhardilla). Se describen las pautas del grupo de trab...

Gobierno y modelado de la seguridad de la información en las organizaciones

OpenAIRE

Ontoria Gonzalo, Sandra

2011-01-01

En este proyecto se estudia el entorno de Gobierno de Seguridad de la Información, con la finalidad de establecer un análisis y diseño de un Sistema de Gobierno de Seguridad de la Información. El entorno de Gobierno se centra en la normativa ISO 27000, aplicando modelos de procesos como Cobit e ITIL, modelos de madurez y métricas para garantizar la Seguridad de la Información a alto nivel, bajo la normativa legal vigente. Asimismo, se van a analizar las herramientas de mercado orientada...

The element of leadership in the validation of a model of quality management for schools

OpenAIRE

Alfaro, Pablo López

2010-01-01

A medida que el país alcanza mejor estado de desarrollo, las organizaciones no educacionales han incorporado paulatinamente a su quehacer, elementos de liderazgo, planificación estratégica, de desarrollo organizacional y evaluaciones de la calidad de su gestión, aplicando planes sistemáticos de mejoramiento. Este acento en la gestión también se ha manifestado en el ámbito de las instituciones educativas, siendo el liderazgo uno de los factores de mayor incidencia en la gestión de estas organi...

El componente liderazgo en la validación de un modelo de gestión escolar hacia la calidad

OpenAIRE

Alfaro,Pablo López

2010-01-01

A medida que el país alcanza mejor estado de desarrollo, las organizaciones no educacionales han incorporado paulatinamente a su quehacer, elementos de liderazgo, planificación estratégica, de desarrollo organizacional y evaluaciones de la calidad de su gestión, aplicando planes sistemáticos de mejoramiento. Este acento en la gestión también se ha manifestado en el ámbito de las instituciones educativas, siendo el liderazgo uno de los factores de mayor incidencia en la gestión de estas organi...

Aplicación de dos pruebas estadísticas de bondad de ajuste en muestras complejas: un caso práctico en el campo forestal

OpenAIRE

Quintero-Méndez, María A.; Durán-Núñez, Mariano J.

2008-01-01

En esta investigación se comparan dos pruebas de bondad de ajuste en términos de su error tipo I: ji-cuadrada de Pearson y Rao-Scott con corrección de segundo orden, aplicadas a datos recolectados mediante técnicas de muestreo que no cumplen los supuestos de independencia e igual probabilidad de inclusión de las observaciones, llamadas muestras complejas. Ambas pruebas se usaron para ajustar categorías diamétricas en una plantación de gmelina (Gmelina arborea), aplicando muestreo sistemático ...

EVALUACIÓN DE ALTERNATIVAS PARA CLIMATIZACIÓN DE ESTANQUES CON ENERGÍA SOLAR PARA CULTIVO DE TILAPIA ROJA (Oreochromis sp), LOCALIZADOS EN LA ZONA FRÍA DEL VALLE DEL CAUCA, COLOMBIA EVALUATION OF ALTERNATIVES FOR AIR CONDITIONING OF PONDS WITH SOLAR ENERGY FOR CULTIVATION OF RED TILAPIA (Oreochromis sp), LOCATED IN THE COLD AREA OF THE CAUCA VALLEY, COLOMBIA

OpenAIRE

Francisco Javier Borja Gallardo; Luis Octavio González Salcedo; Victoria Eugenia Quintero de Vallejo

2006-01-01

La investigación fue desarrollada para que la tilapia roja (Oreochromis sp), especie de pez mÁs producida en Colombia, pueda ser explotada en lugares donde las condiciones óptimas para su normal desarrollo no son las adecuadas, como son las regiones altas con temperaturas por debajo de los 24 °C, aplicando metodologías relacionadas con el aprovechamiento de la energía solar. Las técnicas evaluadas fueron: climatización por medio de colectores solares, climatización por medio de manta térmica,...

Análisis del Método Leader (2007-2013) en Extremadura mediante técnicas SIG y Análisis Multivariado

OpenAIRE

Ana Nieto Masot; Gema Cárdenas Alonso

2017-01-01

Durante los últimos 25 años se vienen aplicando en las zonas rurales europeas, y más concretamente en Extremadura, unas estrategias territoriales con la que activar el desarrollo económico de las mismas y disminuir, en lo posible, sus diferencias respecto a las urbanas mediante la diversificación económica del territorio de actuación a través de la puesta en marcha de proyectos cofinanciados por los fondos europeos, las administraciones nacionales y la población local a través del denominado ...

Análisis cuantitativo de cuarzo-alfa en mezclas de cemento portland anhidro y calcita sintética por difracción de rayos X con equipo Philips PW-1700

Directory of Open Access Journals (Sweden)

Sagrera-Moreno, J. L.

1985-09-01

Full Text Available In this article there are explained the necessary steps to make up a quantitative analysis of alpha-quartz applying the technique of rays X diffraction, in artificial mixtures of anhydrous portland cement and synthetic calcite, which contents are known.

En el presente artículo se explican los pasos necesarios para realizar un análisis cuantitativo de cuarzo-alfa aplicando la técnica de difracción de rayos X en mezclas artificiales de cemento portland anhidro y calcita sintética, cuyos contenidos son conocidos.

Ambientes de aprendizaje para el desarrollo de habilidades metacognitivas durante la resolución de problemas: estudio longitudinal en estudiantes de los últimos semestres de ingeniería química de la UDLAP

OpenAIRE

Ramírez Apud López, Zaira

2013-01-01

En la actualidad, se ha demostrado que los profesionistas del área de las ingenierías, son contratados, retenidos y remunerados por la capacidad que muestran en la resolución de problemas del área laboral (Jonassen et al, 2006) Con base en lo anterior, el presente trabajo propone el desarrollo de Ambientes de Aprendizaje Basados en la Solución de Problemas, en estudiantes1 de la Licenciatura en Ingeniería Química durante sus últimos tres semestres de la Carrera, aplicando los procesos de s...

Lean Six Sigma Startup Methodology (L6SSM): una metodología general de innovación de la calidad aplicada a los sectores de la producción y servicios

OpenAIRE

García Camús, Juan Manuel

2015-01-01

Tesis Doctoral leída en la Universidad Rey Juan Carlos de Madrid en 2015. Director de la Tesis: Javier Martínez Moguerza La calidad, eficiencia, flexibilidad y rapidez en la entrega de un determinado producto o servicio se ha vuelto prioridad en la gestión, lo que ha provocado la necesidad de implementar las llamadas metodologías ágiles. Desde hace pocos años, surge Lean Startup como una nueva tecnología conjunto de éstas y de otras que tradicionalmente se venían aplicando. Las principa...

Investigação sobre a satisfação do usuário dos serviços prestados pelo Metrô de São Paulo: um estudo exploratório, descritivo e ilustrativo com a utilização do modelo de equações estruturais User satisfaction with the Metro of Sao Paulo: an exploratory, descriptive and illustrative study using structural equation modeling

OpenAIRE

André Castilho Ferreira da Costa; Saulo Soares de Souza; Letticia Caruso Thomaz da Silva

2008-01-01

O objetivo desta pesquisa foi discutir a aplicabilidade da metodologia do American Customer Satisfaction Index (ACSI) a situações da realidade brasileira, com base no modelo de equações estruturais. Para tanto, foi realizada uma verificação empírica do comportamento do modelo, aplicando-o à amostra de dados colhida entre usuários dos serviços prestados pela Companhia do Metropolitano de São Paulo - Metrô. Os resultados confirmaram apenas em parte as relações do modelo, sugerindo, principalmen...

Aceptabilidad a suplementos nutricios en mujeres embarazadas o lactando y niños menores de cinco años

OpenAIRE

Martínez Homero; Campero Lourdes; Rodríguez Guadalupe; Rivera Juan

1999-01-01

OBJETIVO. Se llevó a cabo un estudio exploratorio para profundizar en aspectos relativos a la aceptabilidad y el apego al consumo de suplementos nutricios que forman parte de un programa gubernamental de apoyo a la nutrición, dirigido a grupos vulnerables. MATERIAL Y MÉTODOS. Se entrevistó a mujeres embarazadas o en lactancia, así como a madres de niños lactantes, niños destetados y niños menores de dos años con desnutrición. Los datos se recolectaron mediante visitas al hogar, aplicando una ...

Atividade residual de diuron, oxyfluorfen e prometryne no controle de Euphorbia heterophylla Residual activity of diuron, oxyfluorfen, and prometryne for Euphorbia heterophylla control

OpenAIRE

R.S. Oliveira Jr.; J.C. Carneiro; J. Constantin; G. Santos; A.C. Francischini; A.M. Oliveira Neto

2012-01-01

As aplicações de herbicidas em pré-emergência têm por finalidade a obtenção da atividade residual no início do ciclo das culturas. Assim, o objetivo deste trabalho foi avaliar a atividade residual dos herbicidas diuron, oxyfluorfen e prometryne, aplicados isoladamente ou em misturas, no controle de Euphorbia heterophylla. Oito experimentos foram conduzidos em casa de vegetação, aplicando-se doses dos herbicidas ou das misturas aos 30, 20, 10 e 0 dias antes da semeadura da planta daninha (DAS)...

La comunicación de las emociones

OpenAIRE

García Fernández, José-Lorenzo

1991-01-01

Revisión histórica de las aportaciones más significativas de la filosofía, antropología, etología, psicología, etc. acerca de la emoción en sus aspectos expresivo y comunicativo. Identifica, asimismo, las estructuras y regiones del cerebro relacionadas con las emociones e investiga en profundidad el lenguaje del rostro humano. En la segunda parte, la tesis realiza un análisis de algunas obras cinematográficas aplicando las categorías del "análisis transaccional" y de las disciplinas que estud...

Guía de Aplicación de la Técnica de Calidad Seis Sigma en el Proceso de Desarrollo de Software

OpenAIRE

Hinojosa, C.; Monge, D.; Mosquera, V.

2016-01-01

El objetivo del presente proyecto, ha sido desarrollar una guía que permita mejorar el nivel de eficiencia en el control de calidad del proceso de desarrollo de software, aplicando la técnica Seis Sigma, en base a un análisis situacional que evidencie la realidad de las prácticas de calidad en la industria del software ecuatoriano. Los fundamentos sobre el proceso de desarrollo de software, certificaciones de calidad, y Seis Sigma, fueron obtenidos mediante una metodología de investigación ti...

Amor y enamoramiento en personas con discapacidad intelectual. Un campo por explorar

OpenAIRE

Morentin, R.; Arias, B.; Verdugo Alonso, Miguel Ángel; Rodríguez Mayoral, José Manuel

2006-01-01

El amor es considerado uno de los fenómenos interpersonales más importantes, relacionándose además con la salud, la felicidad y el bienestar general. Sin embargo, el acercamiento científico al amor como objeto de estudio no se ha ampliado a las personas con discapacidad intelectual, aun cuando sí se estén desarrollando programas y actuaciones centradas en la educación afectivo-sexual. En este estudio, se pretende iniciar este camino (aún desconocido), aplicando la conocida Escala Triangular d...

Dificultades conceptuales para predecir equilibrios químicos homogéneos y heterogéneos

OpenAIRE

López González, W.

2009-01-01

En este trabajo quedan evidenciados los errores conceptuales en una muestra a la que se aplicó un instrumento, en el que se le planteó distintas situaciones para predecir el desplazamiento de un sistema en equilibrio. Se presentaron dificultades aplicando el principio de LeChatelier en cuanto a: comparaciones masa-concentración, inyección de un gas inerte al sistema, a volumen (V) y temperatura (T) constantes, inyección de uno de los gases intervinientes en el equilibrio a presión (P) y T con...

Estudio bioquímico-clínico en personas ocupacionalmente expuestas a la acción de Agroquímicos y efectos de su uso frecuente sobre la salud

OpenAIRE

Sarabia Nuñez, Consuelo; Negrón Ballarte, Luisa; Meléndez Serrano, María del Carmen; Pérez González, Rocío Milagros

2014-01-01

Con el fin de evaluar las alteraciones con riesgo para la salud que parecen ocasionar algunos compuestos químicos usados en la agricultura, se ha investigado a 68 agricultores ocupacionalmente expuestos de la zona de Huando - Huaral (Lima).Se determinó importantes enzimas de función hepática: la Colinesterasa plasmática (CHE), aplicando el método cinético adaptado por Wierner, la Glutamil transpeptidasa (yGT), según el método de Szasz y las transaminasas (GOT y GPT) mediante el método UV opti...

Medidas preventivas, correctoras y compensatorias del impacto ecológico de carreteras

OpenAIRE

Aizpurúa Giráldez, Nerea

2011-01-01

Las medidas preventivas, correctoras y compensatorias empleadas en los proyectos de carretera son uno de los elementos clave para conseguir la integración ambiental de estas infraestructuras. De ellas dependerá que los posibles impactos ambientales generados durante su construcción y explotación no supongan un detrimento inadmisible de la calidad ambiental. La tipología de medidas que se vienen aplicando desde hace más de veinte años en durante el proceso de Evaluación de Impacto Ambiental (E...

Amortización de Intangibles con cargos variables y gradiente aritmético predeterminado

OpenAIRE

Zans Arimana, Walter

2014-01-01

En este trabajo el objetivo general de la investigación ha sido construir un método que permita amortizar un activo intangible con un procedimiento nuevo, basado en cargos anuales que varían con un gradiente aritmético previamente establecido por la gerencia. La metodología ha sido numérica, aplicando las propiedades de las progresiones aritméticas. Los resultados han llevado a la construcción del mencionado método, concluyendo dicho procedimiento cumple con la definición de amortización que ...

La mortalidad feto-infantil y de menores de 5 años en Cuba: período 2000-2010. The fetal- infant mortality and under 5 years in Cuba: 2000-2010

OpenAIRE

Lorenzo I. Herrera León

2015-01-01

La etapa fetal es vital para el desarrollo y bienestar del futuro ser humano, de ahí que el presente trabajo se haya propuesto como objetivo analizar la evolución de la mortalidad feto-infantil y de menores de 5 años durante el decenio 2000-2010, en Cuba. Para el logro de este se realizaron estimaciones de los eventos vitales que acompañan al proceso del embarazo (abortos e interrupciones, embarazos, mortinatos y nacimiento). A raíz de dichas estimaciones y aplicando técnicas estadísticas de ...

La mortalidad feto-infantil y de menores de 5 años en Cuba: período 2000-2010

OpenAIRE

Herrera León, Lorenzo I.

2015-01-01

La etapa fetal es vital para el desarrollo y bienestar del futuro ser humano, de ahí que el presente trabajo se haya propuesto como objetivo analizar la evolución de la mortalidad feto-infantil y de menores de 5 años durante el decenio 2000-2010, en Cuba. Para el logro de este se realizaron estimaciones de los eventos vitales que acompañan al proceso del embarazo (abortos e interrupciones, embarazos, mortinatos y nacimiento). A raíz de dichas estimaciones y aplicando técnicas estadísticas de ...

Epidemiología y caracterización de los factores de riesgo de diarrea viral bovina y neosporosis en bovinos del valle del Mantaro – región Junín

OpenAIRE

Arauco Villar, Fernando

2015-01-01

Se realizó un estudio epidemiológico de Diarrea viral bovina (DVB) y neosporosis en 425 vacas en producción de 37 hatos del Valle del Mantaro-Región Junín, Perú, mediante ELISA e identificando sus factores de riesgo aplicando una encuesta. Para DVB se encontraron prevalencias: muestral 66.33%, predial 97.3% (36/37) y promedio/hato 64.78%, Concepción tuvo las prevalencias promedio/hato y muestral más altas, luego Jauja, Chupaca y Huancayo; la prevalencia de animales persistentement...

LA GIMNASIA CEREBRAL Y LA CREATIVIDAD DE LOS NIÑOS Y LAS NIÑAS DE 4 A 5 AÑOS DE EDAD DE LA UNIDAD EDUCATIVA LUIS A MARTINEZ DEL CANTÓN AMBATO PROVINCIA DEL TUNGURAHUA

OpenAIRE

Salazar Garcés, María Cristina

2016-01-01

El mundo actual requiere seres humanos con formación integral que fusione conocimientos, habilidades, destrezas, valores, la presente investigación sobre la gimnasia cerebral y la creatividad de los niños y las niñas de 4 a 5 años de edad de la Unidad Educativa Luis A. Martínez del Cantón Ambato, Provincia de Tungurahua, tiene como finalidad investigar el nivel de desarrollo de la creatividad de los niños mencionados, aplicando para ello encuestas dirigidas a los docentes, entrevistas a las a...

Diferencias comportamentales en gallinas ponedoras con y sin el "Método Llovera" durante el período primaveral.

OpenAIRE

Mentzel, Rubén

2009-01-01

Recibido: Dic.2008 | Aceptado: Abr.2009 En trabajos anteriores se demostraron las ventajas del control de moscas en galpones de gallinas ponedoras, aplicando el “Método Llovera”. El mismo consiste en colocar gallinas de descarte en el piso, sin alimentación propia, en una cantidad correspondiente al 10% de los animales del galpón.1 De esta forma se logra disminuir la cantidad de moscas, y aumentar la producción de huevos mejorando la calidad y la rentabilidad. Un ambiente sin moscas es mu...

Aplicación de la filosofía lean management a Merkamueble

OpenAIRE

López Díez, Javier

2015-01-01

RESUMEN: El objetivo de este trabajo es analizar los procesos clave de Merkamueble aplicando los principios de la filosofía Lean Management, los cuales están orientados a la mejora de la gestión actual de la empresa. Para conseguir el objetivo, en primer lugar, se ha realizado la representación de un mapa de procesos de la empresa clasificando los procesos en estratégicos, clave y de apoyo. Posteriormente, se han analizado en mayor profundidad los procesos clave (recepción del cliente, tr...

Cálculo de secciones de cable en baja tensión en una planta de oil & gas

OpenAIRE

Cabeza Sánchez, Álvaro

2014-01-01

Frecuentemente, cuando se afronta el problema del cálculo de las secciones mínimas de cable en baja tensión mediante el criterio de la intensidad máxima admisible y de la caída de tensión, resulta complicado encontrar alguna herramienta que, de una forma sencilla y rápida, proporcione una estimación realista de los diferentes tipos de cable y sus secciones para confeccionar la lista de cables. En este Proyecto Fin de Carrera se desarrolla una hoja de cálculo que, aplicando normati...

Resultados do Grupo de Trabalho de Tecnologias Avançadas IDE do Projecto OTALEX C

OpenAIRE

Vivas, Pedro; Álvarez, Rafael; Mateus, Júlio; Pavo, Marcos; Rubio, J.M.; González, Julián; Soriano, Marcos; Caballero, Carmen; Aparício, Alberto; Batista, T.; Carriço, Cristina; Cabezas, José; Fernández, Luis; Jiménez, Alberto; Gamero, Ulises

2013-01-01

Apresentam-se os resultado do Grupo de Trabalho de Tecnologias Avançadas IDE do projeto OTALEX-C, sendo estes: a geração de dados interligados de elementos geográficos do território OTALEX-C para a publicação de uma Web Semântica, e a captura e publicação de dados ambientais através de serviços padronizados de registo de observações com recurso a sensores, aplicando a standard SOS definida pela OGC. POCTEP 2007-2013

Análisis de los convertidores electrónicos de potencia necesarios para un sistema de iluminación fotovoltaico semi-autónomo.

OpenAIRE

ZAMBRANO PARRA, BRAYAN LEONARDO

2018-01-01

[EN] In this project is expected to analize the main conversors to be used on a solar energy panel converter, this is focused in theorical analysis and a simulation of them applying knowledge accuired all along the degree. [ES] En el presente proyecto se espera realizar el conjunto de convertidores necesario para el funcionamiento de un sistema fotovoltáico, se concentra en el análisis teórico y una simulación de los mismos, aplicando así los conocimientos adquiridos a lo largo de la titul...

Localización probabilística del humanoide Nao en el campo de la RoboCup

OpenAIRE

García Sierra, Juan Felipe; Fernández Llamas, Camino; Matellán Olivera, Vicente; Rodríguez Lera, Francisco Javier

2010-01-01

Una de las habilidades fundamentales que debe poseer un robot para definirse como autónomo es la de autolocalizarse en un entorno dado. En este artículo abordaremos el problema de la localización aplicando técnicas probabilísticas combinando representaciones topológicas y métricas sobre un terreno acotado como es el campo de fútbol de la RoboCup. El artículo presenta también el funcionamiento y resultados obtenidos sobre un conjunto de pruebas simuladas y reales utilizando el humanoide Nao...

Investigación de microorganismos promotores del crecimiento vegetal en cultivos de interés agronómico mediante análisis metagenómico y microbiológico

OpenAIRE

Ramos Cabrera, Efrén Venancio

2018-01-01

La ocurrencia de una amplia diversidad de microorganismos endófitos diazotróficos asociados a cultivares de importancia agronómica ha sido descripta en varias publicaciones aplicando técnicas de secuenciación masiva, huella dactilar y cultivo dependientes. El análisis de las secuencias nifH sugiere que una importante proporción de estos endófitos se corresponden con microorganismos aún sin identificación taxonómica y/o no han sido cultivados in vitro. En estos estudios se encuentra rasgos int...

Rietveld analysis of phase separation in annealed and leach tested Cm-doped perovskite

International Nuclear Information System (INIS)

White, T.J.

1995-01-01

A quantitative powder X-ray diffraction study was made of actinide doped perovskite of bulk composition Ca 0.98919 An 0.98919 Al 0.01081 O 3 where An corresponded to approximately equimolar proportions of Cm-244 and Pu-240. Sections of this sample accumulated irradiation doses up to 7.51 x 10 17 alpha decay events per gram (α/g). The damaged samples were treated in two ways. First, to establish the critical temperature for structural recovery under the reducing conditions of geological repositories, isochronal annealing was carried out at 600, 800, 1,000 and 1,100 C for 12 hours in graphite crucibles. Two groups of perovskites that had previously sustained doses of 4.5 x 10 17 and 7.4 x 10 17 α/g were tested in this way. For the former group, these conditions resulted in up to 9 weight percent (wt%) of available actinide separating as a fluorite-type dioxide near the perovskite surface. In the latter group, calcium was reduced to the metal which vaporized, leaving an excess of refractory titanium that crystallized as rutile. Second, material which has sustained doses of 1.6--4.0 x 10 17 alpha decays per gram was subjected to an MCC-1 leach test for two months at 90 C using a pH ∼ 2 solution. Under these conditions surficial perovskite dissolved congruently to release calcium into solution while the titanium reprecipitated as anatase. The implications of these results for the ultimate disposal of perovskite-bearing polyphase nuclear waste ceramics are considered

Aplicando minería de datos para descubrir rutas de aprendizaje frecuentes en Moodle

OpenAIRE

Alejandro Bogarín Vega; Cristóbal Romero Morales; Rebeca Cerezo Menéndez

2016-01-01

En este artículo, aplicamos técnicas de minería de datos para descubrir rutas de aprendizaje frecuentes. Hemos utilizado datos de 84 estudiantes universitarios, seguidos en un curso online usando Moodle 2.0. Proponemos agrupar a los estudiantes, en primer lugar, a partir de los datos de una síntesis de uso de Moodle y/o las calificaciones finales de los alumnos en un curso. Luego, usamos los datos de los logs de Moodle sobre cada cluster/grupo de estudiantes separadamente con el fin de poder ...

Mejoramiento de cimentaciones en suelos y rocas aplicando las técnicas de grouting

OpenAIRE

Ampuero Cayo, Salomón Edgard; Ampuero Cayo, Salomón Edgard

2012-01-01

Las técnicas de inyecciones de grouting, se conocen desde el año 1802 en Francia, desde entonces se ha recopilado información y se practica esta técnica mejorando cada vez. Los diseños, procedimientos de inyección, están orientados hacia los objetivos básicos, que son el control de agua subterránea y el tratamiento de los macizos rocosos fracturados y suelos sin cohesión. La aplicación de las técnicas de grouting en rocas; reducen el flujo de agua, refuerzan las rocas y mitigan la formaci...

Aplicando minería de datos para descubrir rutas de aprendizaje frecuentes en Moodle

Directory of Open Access Journals (Sweden)

Alejandro Bogarín Vega

2016-01-01

Full Text Available En este artículo, aplicamos técnicas de minería de datos para descubrir rutas de aprendizaje frecuentes. Hemos utilizado datos de 84 estudiantes universitarios, seguidos en un curso online usando Moodle 2.0. Proponemos agrupar a los estudiantes, en primer lugar, a partir de los datos de una síntesis de uso de Moodle y/o las calificaciones finales de los alumnos en un curso. Luego, usamos los datos de los logs de Moodle sobre cada cluster/grupo de estudiantes separadamente con el fin de poder obtener más específicos y precisos modelos de procesos del comportamiento de los estudiantes.

“Prototipo de control de riego tecnificado aplicando la tecnología del arduino”

OpenAIRE

CAYO CABRERA, GUIDO HUMBERTO; UNIVERSIDAD NACIONAL DEL ALTIPLANO

2015-01-01

El riego por aspersión se aplica el agua en suelo asperjado, o fraccionando el caudal en gotas las mismas que humedecen el terreno al tiempo que alcanzan la superficie del mismo. Se trata de un método de riego mecanizado, que asegura un preciso control de la lámina de agua aplicada en función de las condiciones edafo-climáticas y de cultivo y además permite una adecuada tecnificación de la práctica del riego. La metodología propuesta es mediante el riego automatizado y controlado vía web, que...

Desarrollo de un sistema de recogida de datos en Facebook aplicando gamificación

OpenAIRE

Castaño Chillarón, Diego

2015-01-01

El surgimiento del Big Data unido al auge de las redes sociales en los últimos años ha propiciado que éstas almacenen cada vez más datos de los usuarios, en un intento de rentabilizar su modelo de negocio, explotándolos principalmente a través de la publicidad dirigida. Facebook se encuentra a la cabeza en esta carrera por los datos, almacenando información de 1.44 billones de usuarios (datos personales, gustos, relaciones, etc.). Con este creciente ecosistema surgen nuevas oportunidades p...

INCLUSIÓN SOCIAL Y EL RECICLAJE EN LAS INSTITUCIONES EDUCATIVAS APLICANDO LAS TIC’S

OpenAIRE

Juan Calderón Cisneros; Ingrid León Baquerizo; Zoveida Zurita Murillo

2013-01-01

Se propone este trabajo investigativo de carácter ambiental y educativo, como una herramienta para disminuir el elevado volumen de basura que existe en los entornos de la Universidad de Guayaquil. Hay quienes desechan desperdicios, que sin embargo podrían ser de alguna manera recuperados, teniendo en cuenta que la  basura debe estar ubicada en sus respectivos recipientes, siendo separados, clasificados y distinguidos. Las necesidades educativas específicas que presentan los estudiantes con al...

Tomada de Decisão Financeira: Aplicando o Processo Orçamentário

Directory of Open Access Journals (Sweden)

Filipe Prado Macedo da Silva

2014-07-01

Full Text Available Este artigo aborda a dinâmica da decisão financeira e o processo orçamentário no âmbito das empresas. Em vista da globalização e liberalização financeira, a tomada de decisão financeira ganhou importância dentro do processo de gestão empresarial, sobretudo quando afeta o fluxo de caixa e os relatórios contábeis. Algumas empresas – como a M&S Comercial – utilizam o processo orçamentário como ferramenta de apoio na gestão financeira. O orçamento serve de “guia” para os gestores da empresa. No estudo de caso, constatamos que a empresa melhorou seu desempenho econômico-financeiro ao integrar o processo orçamentário na dinâmica da tomada de decisão financeira.

INCLUSIÓN SOCIAL Y EL RECICLAJE EN LAS INSTITUCIONES EDUCATIVAS APLICANDO LAS TIC’S

Directory of Open Access Journals (Sweden)

Juan Calderón Cisneros

2013-12-01

Full Text Available Se propone este trabajo investigativo de carácter ambiental y educativo, como una herramienta para disminuir el elevado volumen de basura que existe en los entornos de la Universidad de Guayaquil. Hay quienes desechan desperdicios, que sin embargo podrían ser de alguna manera recuperados, teniendo en cuenta que la  basura debe estar ubicada en sus respectivos recipientes, siendo separados, clasificados y distinguidos. Las necesidades educativas específicas que presentan los estudiantes con alguna discapacidad visual. Docentes, personal técnico y administrativo, ven en la implementación de una batería de reciclaje con tachos inteligentes, lograr una mejor clasificación, comenzando por difundir la importancia  de combinar  la tecnología con el reciclaje y por mantener el entorno universitario limpio, de tal manera que se proyecte a lo largo del tiempo y tenga un impacto en la conciencia de la comunidad, en relación al cuidado del medio ambiente. Esto generará que se tomen medidas y sistemas para manejar los desechos y sobre todo se motive a  utilizar los recursos necesarios para fomentar nuevas propuestas y generar alternativas para seguir con la cultura del reciclaje y su combinación con la tecnología.

Effect of laser welding parameters on the austenite and martensite phase fractions of NiTi

Energy Technology Data Exchange (ETDEWEB)

Oliveira, J.P., E-mail: jp.oliveira@campus.fct.unl.pt [CENIMAT/i3N, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa (Portugal); Braz Fernandes, F.M. [CENIMAT/i3N, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa (Portugal); Miranda, R.M. [UNIDEMI, Faculdade de Ciências e Tecnologia, Universidade Nova de Lisboa (Portugal); Schell, N. [Institute of Materials Research, Helmholtz-Zentrum Geesthacht, Max-Planck-Str. 1, D-21502 Geesthacht (Germany); Ocaña, J.L. [Centro Láser UPM, Universidad Politécnica de Madrid, Edificio “La Arboleda”, Ctra. Valencia, km 7,300, Campus Sur UPM, 28031 Madrid (Spain)

2016-09-15

Although laser welding is probably the most used joining technique for NiTi shape memory alloys there is still a lack of understanding about the effects of laser welding parameters on the microstructural induced changes: in both the heat affected and fusion zones martensite may be present, while the base material is fully austenitic. Synchrotron X-ray diffraction was used for fine probing laser welded NiTi joints. Through Rietveld refinement the martensite and austenite phase fractions were determined and it was observed that the martensite content increases towards the weld centreline. This is related to a change of the local transformation temperatures on these regions, which occurs due to compositional variation in those regions. The martensite phase fraction in the thermally affected regions may have significant implications on functional properties on these joints. - Highlights: •Synchrotron X-ray diffraction was used for fine probing of the microstructure in laser welded NiTi joints. •Rietveld refinement allowed to determine the content of martensite along the heat affected and fusion zones. •The martensite content increases from the base material towards the weld centreline.

Crystallographic parameters of magnetic Pr{sub 2}Fe{sub 14−x}Co{sub x}B-type alloys determined using anomalous x-ray diffraction with synchrotron radiation

Energy Technology Data Exchange (ETDEWEB)

Galego, E., E-mail: egalego@ipen.br; Serna, M.M.; Ramanathan, L.V.; Faria, R.N.

2017-02-15

Anomalous x-ray synchrotron diffraction was used to determine the crystallographic parameters of PrFeCoB-based magnetic alloys. The effect of cobalt concentration on the crystallographic parameters of the magnetically hard Pr{sub 2}Fe{sub 14−x}Co{sub x}B phase was studied. The results indicate that addition of cobalt has a marked effect on crystal structure. Variation of the c parameter decreased twice as much as the a parameter with increase in Co content. The positions of inequivalent atoms of the magnetically hard matrix phase ϕ in the Pr-based alloys were determined using Rietveld refinement. This permitted determination of the relative distance of each inequivalent atom from its nearest neighbors. Cobalt occupied the 16k{sub 2} site and Fe had a tendency to occupy the 8j{sub 2} sites located between the Kagomé layers. - Highlights: • Good magnetics properties can be achieved with addition of 4% and 8% Co. • Rietveld refinement is proposed for crystallographic parameters studies. • Co has preference to substitute Fe in 16k{sub 2} site and avoid the 8j{sub 2} site.

Effect of vanadium doping on structural and magnetic properties of defective nano-nickel ferrite

Science.gov (United States)

Heiba, Zein K.; Mohamed, Mohamed Bakr; Wahba, Adel Maher; Almalowi, M. I.

2018-04-01

Nano-nickel ferrites defected by vanadium doping (NiV x Fe2-1.67 x O4, 0 ≤ x ≤ 0.25) were prepared using a simple sol gel method. Rietveld analysis revealed a nonmonotonic change in lattice parameter, oxygen parameter and magnetization upon doping with vanadium. Cation distributions suggested from either Rietveld analysis or from experimental magnetic moments were in a good agreement. For low doping values ( x = 0.05), vanadium was residing mainly in octahedral sites, while for samples with vanadium content ( x ≥ 0.1) a significant part of vanadium ions resided at tetrahedral sites; a result which has been confirmed by the analysis of Fourier-transform infrared (FTIR) spectrums obtained for the samples. The transmission electron microscope (TEM) image showed fine spherical particles with size of ˜ 11 nm. All samples showed a superparamagnetic nature with a nonmonotonic change of either magnetization ( M S) or coercivity (H C) with the content of nonmagnetic V5+. The cation occupancies indicated presence of an enormous number of vacancies through doping with high valence cation V5+, making present samples potential electrodes for Li- or Na-ion batteries.

Mn"4"+-activated BaSiF_6 red phosphor: Hydrothermal synthesis and dependence of its luminescent properties on reaction conditions

International Nuclear Information System (INIS)

Zhou, Qiang; Zhou, Yayun; Lu, Fengqi; Liu, Yong; Wang, Qin; Luo, Lijun; Wang, Zhengliang

2016-01-01

In this work, a series of BaSiF_6:Mn"4"+ red phosphors were synthesized through a hydrothermal route. The crystal structure and morphology were characterized by powder X-ray diffraction (XRD) with Rietveld refinement, scanning electron microscopy (SEM), and energy dispersive spectrometer (EDS) in detail. The influence of reaction conditions, including the concentration of KMnO_4 and HF, reaction temperature and time, on the photoluminescence properties were investigated systematically. It can emit intense red light (∼636 nm) under blue light (∼458 nm) illumination. The white LED device based on YAG:Ce–BaSiF_6:Mn"4"+ mixture shows warm white light with low color temperature and high correlated color index, which reveals its potential application in WLED. - Highlights: • The crystal structure of BaSiF_6:Mn"4"+ has been verified using Rietveld refinement. • The optimum hydrothermal reaction condition for BaSiF_6:Mn"4"+ has been confirmed. • The white LED based on YAG:Ce–BaSiF_6:Mn"4"+ mixture presents warmer white light than that only with YAG:Ce.

Mn{sup 4+}-activated BaSiF{sub 6} red phosphor: Hydrothermal synthesis and dependence of its luminescent properties on reaction conditions

Energy Technology Data Exchange (ETDEWEB)

Zhou, Qiang; Zhou, Yayun [Key Laboratory of Comprehensive Utilization of Mineral Resources in Ethnic Regions, Joint Research Centre for International Cross-border Ethnic Regions Biomass Clean Utilization in Yunnan, School of Chemistry & Environment, Yunnan Minzu University, Kunming, 650500 (China); Lu, Fengqi [MOE Key Laboratory of New Processing Technology for Nonferrous Metals and Materials, College of Materials Science and Engineering, Guilin University of Technology, Guilin, 541004 (China); Liu, Yong [Key Laboratory of Comprehensive Utilization of Mineral Resources in Ethnic Regions, Joint Research Centre for International Cross-border Ethnic Regions Biomass Clean Utilization in Yunnan, School of Chemistry & Environment, Yunnan Minzu University, Kunming, 650500 (China); Wang, Qin [College of Chemistry and Chemical Engineering, Yunnan Normal University, Kunming, Yunnan, 650500 (China); Luo, Lijun [Key Laboratory of Comprehensive Utilization of Mineral Resources in Ethnic Regions, Joint Research Centre for International Cross-border Ethnic Regions Biomass Clean Utilization in Yunnan, School of Chemistry & Environment, Yunnan Minzu University, Kunming, 650500 (China); Wang, Zhengliang, E-mail: wangzhengliang@foxmail.com [Key Laboratory of Comprehensive Utilization of Mineral Resources in Ethnic Regions, Joint Research Centre for International Cross-border Ethnic Regions Biomass Clean Utilization in Yunnan, School of Chemistry & Environment, Yunnan Minzu University, Kunming, 650500 (China)

2016-02-15

In this work, a series of BaSiF{sub 6}:Mn{sup 4+} red phosphors were synthesized through a hydrothermal route. The crystal structure and morphology were characterized by powder X-ray diffraction (XRD) with Rietveld refinement, scanning electron microscopy (SEM), and energy dispersive spectrometer (EDS) in detail. The influence of reaction conditions, including the concentration of KMnO{sub 4} and HF, reaction temperature and time, on the photoluminescence properties were investigated systematically. It can emit intense red light (∼636 nm) under blue light (∼458 nm) illumination. The white LED device based on YAG:Ce–BaSiF{sub 6}:Mn{sup 4+} mixture shows warm white light with low color temperature and high correlated color index, which reveals its potential application in WLED. - Highlights: • The crystal structure of BaSiF{sub 6}:Mn{sup 4+} has been verified using Rietveld refinement. • The optimum hydrothermal reaction condition for BaSiF{sub 6}:Mn{sup 4+} has been confirmed. • The white LED based on YAG:Ce–BaSiF{sub 6}:Mn{sup 4+} mixture presents warmer white light than that only with YAG:Ce.

Solvothermal growth of a ruthenium metal-organic framework featuring HKUST-1 structure type as thin films on oxide surfaces.

Science.gov (United States)

Kozachuk, Olesia; Yusenko, Kirill; Noei, Heshmat; Wang, Yuemin; Walleck, Stephan; Glaser, Thorsten; Fischer, Roland A

2011-08-14

Phase-pure crystalline thin films of a mixed-valence Ru(2)(II,III) metal-organic framework with 1,3,5-benzenetricarboxylate (btc) as a linker were solvothermally grown on amorphous alumina and silica surfaces. Based on the Rietveld refinement, the structure of Ru-MOF was assigned to be analogous to [Cu(3)(btc)(2)] (HKUST-1). This journal is © The Royal Society of Chemistry 2011

A novel LaFeO3−XNX oxynitride. Synthesis and characterization

International Nuclear Information System (INIS)

Sierra Gallego, G.; Marín Alzate, N.; Arnache, O.

2013-01-01

Highlights: ► LaFeO 3 perovskite synthesized by auto combustion method. ► LaFeO 3−X N X oxynitride produced by ammonolysis reaction. ► Oxynitride characterized by XRD, Rietveld, SEM, EDX, BET, Raman, TGA and FTIR. ► Partial replacement of oxygen by nitrogen increases slightly the cell parameters. ► TGA shows that oxynitride start to decompose in air above 550 °C. Evolution of N 2 and NO was detected. - Abstract: A perovskite LaFeO 3 was synthesized by auto combustion method and then LaFeO 3−X N X oxynitride was produced by ammonolysis reaction. The synthesized LaFeO 3−X N X oxynitride was characterized by X-ray diffraction (XRD), Rietveld refinement, scanning electron microscopy (SEM), energy dispersive X-ray (EDX), Brunauer–Emmett–Teller (BET) nitrogen adsorption, particle size distribution, Raman spectroscopy, thermogravimetric analysis (TGA) and Fourier transform infrared spectroscopy (FTIR). Nitrogen effect into the perovskite structure was confirmed by DRX. The structure refinement using the Rietveld method indicates that partial replacement of oxygen by nitrogen increases slightly the cell parameters of the LaFeO 3 perovskite. FTIR analysis show that bands at 995 and 1070 cm −1 in the oxynitrides spectra could be assigned to the stretching vibration modes of Fe–N bonds in the FeO 6−X N X octahedral. Thermogravimetric analysis (TGA) showed that LaFeO 3−X N X oxynitride series start to decompose in air above 550 °C. During the decomposition it was found that some amount of nitrogen stays retained in the structure forming intermediate compounds. MS analysis of the gaseous products reveals the evolution of N 2 and NO, suggesting a complex reaction mechanism. To our knowledge, there are no reports on the synthesis and characterization of the LaFeO 3−X N X oxynitrides.

Terra-cotta figurines from the Roman theatre of Malaga (Spain: An archaeometric study

Directory of Open Access Journals (Sweden)

Compaña, J. M.

2014-06-01

Full Text Available A series of 22 figured Phoeno-Punic and Roman terra-cottas, of high relevant archaeological and patrimonial values, have been studied. The samples were recovered in the Roman Theatre of Malaga (Spain. A thorough analysis including stereomicroscopy, elemental analysis by WDXRF, mineralogical analysis by XRPD coupled with the Rietveld method, and SEM, has been carried out. Highly diluted fused glass beads probed to be enough for the X-ray fluorescence analyses, minimizing the damage to the samples. For selected samples, in addition to the classical use of the Rietveld method, the G-factor external-standard approach has been employed to get full quantitative crystalline and amorphous phase analysis. The analytical results allow proposing a local regional provenance for the main part of the samples, being a relevant data for several artifacts, not contextualized due to stratigraphic alterations in the site. In addition, some relevant samples, for instance a theatrical mask fragment (TRC005, are likely foreign. The overall amorphous is not negligible in phase quantification, accounting for up to 50 wt %. Technologically, all terra-cotta samples are similar, made of calcareous clays, fired at ~700-950 ºC.Se han estudiado 22 terracotas figuradas feno-púnicas y romanas, de alto valor arqueológico y patrimonial. Las muestras proceden de las excavaciones del Teatro romano de Málaga (España. El análisis realizado incluye estereomicroscopía, análisis elemental mediante WDXRF, análisis mineralógico cuantitativo mediante el método de Rietveld de los datos de XRPD y SEM. Para minimizar el daño realizado a las muestras, se prepararon perlas muy diluidas, que han demostrado ser suficientes para los análisis de fluorescencia de rayos-X. Para muestras selectas, además del análisis usual mediante el método de Rietveld, se ha utilizado el método del estándar externo mediante el factor-G para obtener análisis cuantitativos de fases cristalinas y

Estudio comparativo de la pérdida de vitamina C en chalarina (Casimiroa edulis por cuatro métodos de deshidratación

Directory of Open Access Journals (Sweden)

Judith Castañeda

2010-01-01

Full Text Available El objetivo de este estudio fue comparar la pérdida de vitamina C de la chalarina después de aplicar cuatro métodos de deshidratación: deshidratación osmótica a vacío combinada con secado convectivo, secado convectivo, deshidratación osmótica a vacío combinada con liofilización, y liofilización. La chalarina fresca fue acondicionada en forma de cubos de 1 cm de arista; se determinó el contenido de vitamina C y otras propiedades químicas de la pulpa. Los polvos obtenidos fueron caracterizados: contenido de vitamina C, contenido de humedad, aw, densidad, ángulo de fluencia y compresibilidad. La pulpa de chalarina fresca presentó un contenido de vitamina C de 29.75 mg/100g. La deshidratación osmótica a vacío redujo este contenido hasta 15.75 mg/100g, que combinado con secado convectivo se llega a 9.31 mg/100g; en tanto, combinado con liofilización se obtuvo 14.98 mg/100g. Aplicando sólo secado convectivo se obtuvo 7.05 mg de vitaminaC/100g de polvo de chalarina, mientras que aplicando sólo liofilización se obtuvo 23.63 mg/100g. Se concluye que el polvo obtenido por deshidratación osmótica a vacío-secado convectivo presenta mejores características fisicoquímicas que los polvos obtenidos con los otros métodos de deshidratación.

Prevalencia y caracterización de la población en condición de discapacidad del municipio de Los Santos (Santander, Colombia, 2011

Directory of Open Access Journals (Sweden)

Martha Liliana Hijuelos Cárdenas

2012-01-01

Full Text Available Objetivo: Determinar la prevalencia y caracterizar la población en condición de discapacidad del municipio de Los Santos (Santander, Colombia, durante 2010 y 2011. Materiales y métodos: Se realizó un estudio descriptivo aplicando el instrumento de registro "Encuesta a Personas con Discapacidad y su cuidador". Estudiantes de último año de fisioterapia y bacteriología de la Universidad de Santander (UDES, previamente entrenados, recogieron la información mediante entrevista. Se realizó un análisis estadístico descriptivo aplicando medidas de tendencia central y frecuencias absolutas y relativas. Resultados: Se encontraron 108 Personas con Discapacidad (PCD, la prevalencia de discapacidad de esta población fue de 1,3% (IC 95% 1,1-1,6, la vereda con mayor prevalencia fue Los Teres (9,4%; IC95% 5,1-15,5. De las 108 PCD, el 48% corresponde a género femenino y el 47,2% se encuentra entre 15 y 44 años. La estructura corporal con mayor deficiencia fue el sistema nervioso, con un 64,8%, y las actividades de demanda general fueron las más afectadas (57,4%. Los problemas con servicios, sistemas y políticas de transporte, seguro social, salud y educación constituyen el principal facilitador (57, 4%. Conclusión: La discapacidad como problema de salud pública afecta las actividades, participación y desempeño de las PCD, lo cual disminuye su desarrollo individual y sus oportunidades de integración a la sociedad.

Important stages in the development of Romanian accounting profession (from 1800 up to now

Directory of Open Access Journals (Sweden)

Adriana Tiron Tudor

2007-07-01

contables quedaron destruidos; en el último período, desde 1990 hasta nuestro días, Rumania comenzó a mejorar la convergencia de su sistema contable, aplicando en una primera etapa el modelo francés, para continuar luego en nuestros días con su aproximación a los IFRS. El papel jugado por la profesión contable en las últimas décadas es crucial, debido a su motivación y los deseos de implantar “el mejor” sistema contable, así como su actividad diaria, desarrollada en provecho de sus miembros.

La Contabilidad Pública en América Latina y el Devengo en Ecuador

OpenAIRE

Jazmín Sánchez; David Pincay

2013-01-01

Por una parte, muchos países de Latinoamérica vienen aplicando la Contabilidad Pública bajo el Método de Acumulación o Devengo. Por otra, el Internacional Federation Of Accountants (IFAC), a través de la Junta de Normas Internacionales de Contabilidad para el Sector Público (ISPASB), busca armonizar la información contable y financiera de las entidades públicas a nivel mundial. ¿Cuál podría ser la relación entre la práctica actual de la Contabilidad Pública en los países de Latinoamérica y la...

Política Social Comparada entre países de la Alianza del Pacífico y de la Unión Europea: México, Finlandia y España

OpenAIRE

Vidal Figueroa, Carla

2014-01-01

En la actualidad no existen estudios comparativos que midan de forma global la política social como input de los gobiernos. Una alternativa es la inclusión de diversos indicadores relevantes para la política social en un solo índice, que permita realizar un análisis estadístico y comparativo de diferentes países. El objetivo de este estudio es conocer la factibilidad de medir la política social basándonos en sus input y aplicando el Social Policy Index (SPI) en tres países de diferente régime...

Implementación de trazados viales, según el uso y ocupación del suelo (COS – CUS), en ciudades del Ecuador con menos 260.000 habitantes

OpenAIRE

Ayabaca Cazar, Fabián Ramiro

2014-01-01

El objetivo de esta investigación es establecer un esquema básico de procedimientos para la implementación de un estudio que permita el desarrollo de una red vial aplicando la reglamentación de uso y ocupación del suelo, en relación con las nuevas leyes vigentes, así como, facilitar al técnico municipal con una guía para establecer los estudios necesarios previos a la aplicación de un diseño de un trazado vial. En la parte inicial de investigación permitió identificar las estructuras legal...

Identificación y caracterización sindromológica desde la medicina tradicional china (MTC) del cuadro clínico de mujeres ingresadas al Hospital Gíneco-Obstétrico Isidro Ayora (HGOIA) y al Hospital Carlos Andrade Marín (HCAM) con diagnóstico biomédico de preeclampsia CIE10 O14

OpenAIRE

Mena Echeverría, Fabián Eduardo

2017-01-01

Se estudiaron 30 casos de mujeres ingresadas con diagnóstico de preeclampsia en los hospitales Gíneco Obstétrico Isidro Ayora (HGOIA) y Carlos Andrade Marín (HCAM) de Quito, entre los meses de junio y septiembre de 2016, aplicando la historia clínica de medicina tradicional china ACUMOX, con el fin de identificar los síndromes de la medicina tradicional china (MTC) en estas 30 mujeres. El cuadro clínico de estas mujeres corresponde a 12 síndromes diferentes, desde la óptica de la MTC, de los ...

Causas Jurídicas de la Contaminación Sonora por Ruido, en las principales zonas de la Ciudad de Arequipa, entre los años 2009 al 2013

OpenAIRE

Villagómez Riveros, Álvaro Jesús

2017-01-01

RESÚMEN El presente trabajo de investigación sobre las Causas Jurídicas de la Contaminación Sonora o también conocido como Ruido Ambiental, parte de la hipótesis por la cual la población arequipeña percibe un gran malestar debido a que siente que no se está aplicando de manera adecuada las correspondientes leyes y normativas para atenuar esta, planteándose como objetivos en el presente trabajo, el explicar las causas jurídicas que tiene la contaminación sonora en la ciudad de Arequipa, det...

Supervisión pedagógica y estrés laboral de docentes en IEE, Red 10, UGEL 06, Ate, 2015

OpenAIRE

Aliaga Pongo, Yolanda

2015-01-01

El presente trabajo de investigación titulado Supervisión pedagógica y estrés laboral de docentes en IEE Red 10, UGEL 06, Ate, 2015, tuvo como objetivo determinar la relación que existe entre la supervisión pedagógica con el estrés laboral. La población de estudio estuvo constituída por 171 docentes y la muestra fue de 120 aplicando la fórmula de Arkin y Colton. Esta investigación se desarrolló bajo un diseño no experimental de nivel correlacional de corte transeccional, con...

TELECONTROL DE GESTIÓN DE ALARMAS EXTERNAS EN UNA RADIO BASE

OpenAIRE

Lizano Bravo, Xavier Gonzalo

2015-01-01

El “Telecontrol de Gestión de alarmas externas en una radio base” permite administrar y controlar de maneraremota la posición del mástil telescópico de una radio base móvil de telecomunicaciones, además el sistema de la radio base provee la seguridad necesaria de los equipos dentro la misma, aplicando hardware y software libre lo que permitirá disminuir el coste para las empresas de telecomunicaciones. Para poder administrar la posición del mástil telescópico de la radio base móvil...

RESPUESTA DE 12 VARIEDADES DE TRIGO A LA SALINIDAD EN LAS ETAPAS INICIALES DEL CRECIMIENTO

OpenAIRE

L. Argentel; L. M. González; R. Plana

2006-01-01

Con el objetivo de analizar la respuesta varietal del cultivo de trigo a la salinidad en las etapas iniciales del crecimiento de las plántulas, se montó un experimento con 12 variedades, aplicando dos niveles de NaCl en la solución. Las variables evaluadas fueron la absorción de agua por las semillas, altura de las plantas y longitud de la raíz, y la acumulación de biomasas fresca y seca. Mediante un análisis de componentes principales, se establecieron los indicadores de mayor contribución a...

Estudio de los Tweens y las Redes Sociales, Tacna, 2016.

OpenAIRE

Mamani Mamani, Deysi Gaby; Gonzalo Jara, Gustavo Richard; Yufra Tozo, Wilfredo Renato

2016-01-01

La tesis propuesta en las siguientes páginas: “Estudio de los Tweens y las Redes Sociales, Tacna, 2016”, busca poner en evidencia las preferencias, razones de uso, y uso, de las redes sociales por parte del grupo etario conformado por los tweens o pre adolescentes (Niños entre 8 y 12 años). La investigación presentada es de carácter descriptivo, de diseño no experimental y transversal, y se llevó a cabo aplicando un cuestionario (Asistido), conformado por 11 preguntas, a 146 niños entre la...

Clusters de religiosidade da juventude universitária portuguesa

OpenAIRE

Coutinho, José Pereira

2014-01-01

Este artigo apresenta resultados da tese de doutoramento do autor, baseados nas crenças e práticas religiosas e nas atitudes em relação ao casamento, vida e sexualidade. A amostra incluiu 500 estudantes universitários das universidades públicas de Lisboa. Aplicando análise de correspondências múltiplas e análise de clusters a estas crenças, práticas e atitudes, foram produzidos três clusters ou tipos de religiosidade: católicos nucleares, católicos intermédios e não católicos. Estes clusters ...

Direct piezoelectric effect d33 non-linearity in PZT ceramics

OpenAIRE

Pérez Pérez, Rafael; Albareda Tiana, Alfonso; Pérez Codina, Estel; García García, José Eduardo; Tiana Alsina, Jordi; Gorri Ochoa, José Antonio

2006-01-01

Se ha implementado una nueva técnica de medida aplicando un esfuerzo uniaxial sobre la muestra y midiendo la carga generada. Se aplica un esfuerzo suficientemente intenso para producir efectos no lineales, y se analiza la respuesta no sólo en función de la amplitud del esfuerzo sino de su valor instantáneo. Se ha observado que el coeficiente d33 aumenta siempre linealmente con la amplitud, tanto en las cerámicas PZT comerciales blandas como en las duras, en este último caso al revés de lo qu...

Sucesos estresantes y sus impactos en mujeres y jóvenes de la comunidad de cuitzeo, Michoacán: El ciclo de la migración México-EUA en sus familias

Directory of Open Access Journals (Sweden)

Nydia Obregón-Velasco

Full Text Available El presente trabajo describe algunos sucesos de vida estresantes y los impactos que tienen en la salud de las mujeres y sus hijos jóvenes, a partir de la migración hacia EUA de algunos de sus familiares directos, lo cual favorece el ciclo de migración en la familia. Se utilizó la metodología cualitativa con un enfoque de participación-acción, aplicando grupos focales, entrevistas y observación participante durante diferentes actividades realizadas en la comunidad de Cuitzeo, Michoacán, tales como conferencias y talleres.

Optimización de un nuevo proceso electroquímico para descontaminación de residuos finos de escombrera de mina

OpenAIRE

Nogueira Henriques-Rosa, Manuel Alberto

2016-01-01

[ES]La falta de un proceso de descontaminación de residuos de escombreras de mina fue el problema a superar en este trabajo conducente a la obtención del título de doctor. Los estudios iniciales se basaron en la caracterización física y química de los residuos de la mina de wolframio de Barruecopardo (provincia de Salamanca) y sirvieron como base para el posterior estudio sobre la eliminación del arsénico, el hierro y el manganeso presentes en esos residuos aplicando el nuevo método de tr...

Diseño de un modelo de descripción, valoración, clasificación y remuneración de puestos para la empresa Novacero S.A., planta Lasso

OpenAIRE

Cajas Garzón, Alexandra Maribel

2012-01-01

208 hojas : ilustraciones, 29 x 21 cm El presente proyecto de titulación tiene por objetivo diseñar un Modelo de Descripción, Valoración, Clasificación y Remuneración de Puestos, aplicando la Metodología HAY de Valoración de Cargos por Perfiles y Escalas, para la Empresa NOVACERO S.A. Planta Lasso. Se definió un Mapa de Procesos, considerando los que están orientados a satisfacer las necesidades del cliente interno y externo lo cual es un insumo básico para proceder con la identificación ...

Aplicación de la nueva plataforma virtual (Moodle) en el proceso de enseñanza/aprendizaje del Análisis de estados financieros en la UCM

OpenAIRE

Rodríguez Paredes, Mercedes; Rodríguez López, Ángel; Fidalgo Cerviño, Esther

2011-01-01

El objetivo principal de este proyecto es el diseño y desarrollo de metodologías en la enseñanza/aprendizaje universitaria del Análisis de estados financieros, aplicando la filosofía y utilizando las herramientas de la nueva plataforma (Moodle), con el objetivo de contrastar la hipótesis de que la enseñanza a través de la plataforma virtual motivará mucho más a los discentes, de forma que los conocimientos y competencias en el área de referencia se verán ampliamente potenciados. Así, el desar...

Diseño de una línea piloto htst para el laboratorío de operaciones unitarias de la carrera de ingeniería en alimentos (ESPOL)

OpenAIRE

Cornejo Z., Fabiola

2009-01-01

El objetivo del presente trabajo fue el de obtener el diseño de una línea de pasteurización HTST para leche y jugos de baja viscosidad, que será utilizada como unidad didáctica de enseñanza. Primeramente se realizó un análisis a las Industrias de Alimentos de la Costa ecuatoriana para determinar las operaciones de mayor aplicación y se determinó, aplicando el diagrama de Pareto, que estas son Congelación-Refrigeración, Esterilización y Pasteurización, justificando así el objetivo principal. L...

COMPETITIVIDAD DE LA PEQUEÑA EMPRESA DEL SECTOR ORNAMENTALES EN ATLIXCO, MÉXICO

OpenAIRE

Vlashskiv Mosquera Aldana

2010-01-01

El objetivo principal de esta investigación es presentar el perfil competitivo de las pymes del sector ornamentales. Para este análisis se hizo una evaluación de once pymes, aplicando el modelo porteriano. Con las tablas que se presentan en los resultados, es posible realizar una comparación de los factores con los ideales del modelo de medición; dicha comparación permite a los empresarios percatarse de su posición competitiva. Derivado del análisis y la evaluación de la muestra se concluye q...

Análisis de nuevas perspectivas de innovación en el sector de la automoción. Reducción de peso en elementos móviles con bajo coste

OpenAIRE

Morón Morte, Juan Carlos

2011-01-01

El aumento del precio del petróleo, y las nuevas normativas de contaminación, así como la necesidad de crear un vehículo eléctrico de mayor autonomía, ha provocado que las firmas que desarrollan y fabrican automóviles hayan tenido que intensificar sus esfuerzos en reducir el peso de los mismos. Y las puertas de los automóviles, son unos de los elementos en los que se trabaja con empeño para reducir su peso, garantizando siempre su resistencia mecánica y estética, aplicando dife...

Preparación Física con niños y jóvenes. Una perspectiva metodológica

OpenAIRE

Los Santos i Poquet, Carles

2000-01-01

La gran mayoría de los profesionales y no profesionales del entrenamiento deportivo nos movemos o trabajamos sobre todo con niños y niñas de diversas edades y no tanto con categorías de adultos. La infancia y la adolescencia son unas etapas muy delicadas en la vida de la persona y esto me hace pensar si trabajamos con ellos correctamente desde un punto de vista pedagógico, aplicando una metodología adecuada para ellos y si buscamos lo que les corresponde para su edad, a nivel físico y deporti...

Protocol synchronization of estrus and ovulation in sheep

OpenAIRE

Almeida, Marcelo Ferreira de

2009-01-01

Objetivou-se testar o protocolo hormonal para IATF (inseminação artificial em tempo fixo) com progesterona por 6 dias aplicando-se eCG (gonadotrofina Coriônica Eqüina) ou BE (Benzoato de Estradiol) e indução de estros utilizando-se: esponjas vaginais impregnadas com MAP (acetato de medroxiprogesterona) por 6, 9 e 14 dias ou dose única de PGF2a ou efeito macho. Experimento 1: No D0 cada ovelha (n=31) recebeu CIDR sendo divididas aleatoriamente em 3 grupos: G-C (controle) CIDR por 9 dias e na r...

Prevención primaria

OpenAIRE

Henao Gaviria, Luis Fernando

1989-01-01

Pretende este trabajo sobre "Prevención primaria" brindar en forma general una seria de conceptos sobre la salud y la enfermedad, las diferentes barreras que se pueden interponer para que esta no se presente o si se presenta sea lo menos virulenta posible, si deja secuelas buscar que el paciente las trate de superar y evitar la muerte, se logra lo anterior aplicando los niveles de prevención de Leavell y Clark, se hará enfasis en el 1° y 2° nivel que corresponden al fomento o promoción de la ...

Seguridad y salud ocupacional en una empresa maderera peruana: 2007-2008

OpenAIRE

Fartolino Ushinahua, Gabriela

2010-01-01

Objetivo: Conocer la situación de la seguridad y salud ocupacional en una empresa maderera ubicada en la provincia de Loreto, Amazonía peruana, a fin de generar información para tomar medidas correctivas. Método: Para conocer la percepción de los trabajadores se utilizó la técnica de la en-cuesta, aplicando 157 cuestionarios al personal de planta. La información de casos de accidentes y enfermedades fue tomada de las fichas de accidentes de trabajo y los descansos médicos de la oficina de per...

Estandarización de la PCR para el diagnóstico del virus de la Hepatitis B en el Perú

OpenAIRE

Hijar, G; Carrillo, C; Padilla, C; Cabezas, C; Suárez, M; Romero, G; Montoya, Y

1998-01-01

La detección del ADN del virus de la Hepatitis B, (VHB) es el marcador más sensible para determinar la replicación activa e infectividad del virus circulante. Por esta razón la Reacción en Cadena de la Polimerasa (PCR) fue aplicada satisfactoriamente usando primers específicos para gen del antígeno de superficie (HBsAg). Un fragmento de 260 bp fue amplificado in vitro a partir de 200 µl. de sueros de pacientes aplicando PCR. La tecnología de PCR está siendo aplicada en el diagnóstico de pacie...

Criminología biológica: Una mirada desde la genética forense/Biological criminology: a view from the forensic genetics

OpenAIRE

Rosa Elizabeth Carrera Palao

2017-01-01

El presente artículo tiene como objeto establecer el estado del arte en neurobiología en torno a la predisposición genética que determina la conducta agresiva, en el ámbito de las neurociencias, y etiopatogenia de la anatomía patológica en los trastornos de personalidad antisocial, que caracteriza la conducta violenta del comportamiento delictivo, de interés a la criminología biológica. Aplicando el método de búsqueda selectiva no sistemática de información relevante de investigaciones ci...

Burnout y problemas de salud mental en docentes: diferencias segun características demográficas y sociolaborales

OpenAIRE

Marenco-Escuderos, Alled Damela; Ávila-Toscano, José Hernando

2016-01-01

Resumen A través de este estudio se evaluó la existencia de diferencias entre las manifestaciones de burnout y los problemas de salud mental en docentes de acuerdo con sus características demográficas y sociolaborales. La evaluación se cumplió con 235 docentes del nivel medio académico de cuatro instituciones oficiales en Colombia, aplicando el MBI-Ed y el GHQ-28 a través de un estudio empírico de diseño comparativo. Se observó mayor agotamiento y baja realización profesional entre las mujere...

PROGRAMA DE INTERVENCION PARA ELEVAR LOS NIVELES DE AUTOESTIMA EN ALUMNAS DE SEXTO AÑO BASICO

OpenAIRE

Valdés G, Lídice

2001-01-01

Este trabajo corresponde a un estudio de medición de los Niveles de Autoestima en las escalas General, Social, Escolar y Hogar, a través del Inventario de Autoestima de Coopersmith (1984), en niñas de sexto año básico, Escuela México de Valdivia, con rasgos de inmadurez en la interacción social. Se realizaron dos mediciones, aplicando el diseño preexperimental de pretest y postest al mismo grupo-curso. Los resultados de las mediciones, efectuadas el primer semestre de los años 1999 y 2000, mu...

Evaluación de riesgos ergonómicos del puesto de auxiliar de topografía en las empresas de construcción

OpenAIRE

Gros, Joaquín

2012-01-01

El Fundamento Básico objeto del trabajo, es adquirir la destreza suficiente en el manejo de los métodos de evaluación de riesgos ergonómicos, aplicando y desarrollando de manera práctica los conocimientos teóricos vistos en la fase anterior del máster. Para ello, en el desarrollo de este trabajo se va a proceder a realizar la evaluación de los riesgos ergonómicos a los que está expuestos los trabajadores que ocupan el puesto de Auxiliar de Topografía en las obras de construcción.

Hacia el establecimiento de un nuevo ethos de la actividad física

OpenAIRE

Andrade Patarroyo, Johny Leandro

2013-01-01

Tesis (Magister en Educación). Universidad Católica de Manizales, Facultad de Educación, 2013 Esta obra de conocimiento da cuenta de una experiencia de vida, en conjunción con la realidad de los formadores que han puesto en escena su desinterés por los paradigmas contemporáneos de la Actividad Física, en lo referente a su desarrollo formativo. Es decir, aplicando las nuevas tendencias de actividad física como las clases grupales a través de juegos lúdicos, rumba terapia o danza aeróbica;si...

Un modelo para la valuación de intangibles. Aplicación a las franquicias de la industria restaurantera en México

OpenAIRE

RODRÍGUEZ BATRES, AXEL

2010-01-01

La presente Tesis Doctoral se enmarca dentro del campo de la valoración de empresas, aplicando la metodología de valoración analógica a las empresas franquiciadas en el sector de la hostelería en México. El principal objetivo es el desarrollo de un modelo de valoración para el conjunto de las empresas franquiciadas restauranteras que operan en todo el país, con el fin de brindar a los empresarios de este modelo de negocios, una herramienta para la estimación del valor comercial y facilit...

A vueltas con la alfabetización visual: lenguaje y significado en las películas de Wes Anderson

Directory of Open Access Journals (Sweden)

José Gabriel Ferreras Rodríguez

2008-01-01

Full Text Available El presente artículo tiene por objetivo discutir algunos elementos del concepto de la alfabetización visual, aplicando, luego, las herramientas de análisis de imágenes a las películas de Wes Anderson, como ejemplos del manejo intencional de las imágenes para transmitir determinados significados. The present article aims to discuss, firstly, some elements encompassed in the definition of visual literary and, secondly, to apply some image analysis tools to Wes Anderson’s movies, as examples of intentional pictorial organization so as to convey specific meanings.

Exploración de la violencia sexual en la ciudad de Bogotá: una aplicación de técnicas de minería de datos

OpenAIRE

Nelson J. Garnica; Ángela Marcela Olaya Murillo

2011-01-01

Este estudio ofrece una aproximación a la violencia sexual utilizando datos de fuente secundaria y aplicando algunas técnicas de minería de datos. La fuente de datos utilizada es el Instituto Nacional de Medicina Legal y Ciencias Forenses, y los algoritmos aplicados son Selección por Características, C5.0 y K-Means. Antes de la aplicación de dichas técnicas se hace una aproximación teórica a la violencia sexual, para apreciar la forma como se ha abordado este tipo de violencia y la manera com...

Utilidad de la relación estratégica comunitaria y el marketing en el sector de bebidas alcohólicas

OpenAIRE

Mendieta Pinzón, Waldo Alejandro; Navarro Duque, Francisco José; Romero Sierra, Edisson Alejandro

2014-01-01

El estudio busca demostrar la utilidad que tiene la relación estratégica comunitaria en el sector de bebidas alcohólicas en Colombia y cómo la utilizan a través del marketing. Cómo estas funcionan en el sector y si las organizaciones las están aplicando; si lo hacen qué tipo de estrategias emplean para adentrarse y relacionarse con su entorno. Se identifica la efectividad de estas estrategias; si en realidad están promoviendo el desarrollo de la comunidad como el de la organización y paso a s...

MÉTODO MULTIRRESÍDUO PARA DETERMINAÇÃO DE MICOTOXINAS EM VINHO POR UPLC-MS/MS

OpenAIRE

Laís Weber Righi

2013-01-01

Um método rápido usando cromatografia líquida de ultra eficiência acoplada a espectrometria de massas (UPLC-MS/MS) foi implementado e otimizado para proporcionar a determinação completa de 36 micotoxinas em amostras de vinhos. A extração foi realizada com acetonitrila, aplicando o método QuEChERS (Quick, Easy, Cheap, Effective, Rugged, Safe; em português: Rápido, Fácil, Barato, Efetivo, Robusto e Seguro) modificado. Tradicionalmente, o método QuEChERS é muito conhecido na determinação de múlt...

Alterações do desenvolvimento de crianças prematuras nascidas de mães com malária no periodo gestacional

OpenAIRE

Simões, Maria da Conceição Ribeiro

2012-01-01

Objetivo : O estudo buscou avaliar as alterações no desenvolvimento de crianças prematuras nascidas de mães com malária no periodo gestacional, em Porto Velho, Rondônia. O objetivo principal é descrever as alterações encontradas nessas crianças aplicando um teste preditivo para alterações no desenvolvimento e compará-las à um grupo controle de crianças prematuras nascidas de mães que não apresentaram malária no periodo gestacional. Métodos : Por ser um estudo do tipo transvers...

Selección de materiales para la fabricación de equipamiento en plantas productoras de ácido fosfórico.

OpenAIRE

SCHORR, MICHAEL; VALDEZ, BENJAMíN; OCAMPO, JUAN DE DIOS

2011-01-01

El ácido fosfórico (AF) es un importante ácido industrial utilizado en la industria química, agroquímica, incluyendo fertilizantes, agua. energia, bioingenierla. aceros, alimentos, bebidas, etc. Se produce de roca fosfórica (RF) aplicando dos procesos: Via húmeda, por ataque con ácido sulfürico y por reacción con ácido clorhídrico y posterior extracción con solventes orgánicos. Estas plantas muestran un alto riesgo de corrosión puesto que manejan y procesan ácidos corrosivos, operan bajo seve...

Aplicación del Software MAT6 y su influencia en el rendimiento académico en el área de matemática del sexto grado de la I.E. 6020 Villa María del Triunfo, 2012

OpenAIRE

Rojas Vargas, Jesús Luis Alberto; Chuquihuamaní Aguilar, Wilder José

2015-01-01

El bajo rendimiento académico en matemática de los escolares es un problema que muchos docentes tratan de superar aplicando variadas estrategias en la enseñanza de matemática. En ese sentido, esta investigación busca responder el problema general: ¿Cómo influye la aplicación del software Mat6 en el rendimiento académico en el área de matemática de los estudiantes de sexto grado de primaria de la I.E. 6020. Villa maría del Triunfo, 2012? y como objetivo general: Explicar la i...

Riscos ocupacionais autorreferidos por trabalhadores de uma indústria de produção de fertilizantes – RS – Brasil

OpenAIRE

Liane Silveira da Rosa; Leticia Machado Pereira; Leticia Silveira Cardoso; Marta Regina Cezar-Vaz; Valdecir Zavarese da Costa

2016-01-01

Objetivo: descrever a exposição a riscos ocupacionais autorreferida por trabalhadores de uma indústria de fertilizantes sólido e líquido no Extremo Sul do Rio Grande do Sul – Brasil. Método: estudo descritivo, realizado com 78 trabalhadores, dos quais 49 atuavam no setor de produção e 29 no de movimentação e ensaque. Produziu-se uma análise quantitativa, aplicando-se a estatística descritiva para apresentar as características dos trabalhadores e a exposição aos riscos ocupacionais autorreferi...

A new approach to texture measurements: Orientation distribution function (ODF) determination by Rietveld refinement

International Nuclear Information System (INIS)

Vondreele, R.; Larson, A.; Lawson, A.; Sheldon, R.; Wright, S.

1996-01-01

The preferred orientation of crystal grains within a manufactured part is described most fully by its orientation distribution function (ODF), which is a mapping of the probability of each of the possible grain orientations with respect to the exterior dimensions. Traditionally, an ODF is determined from pole figures for a relatively small number of reflections. These pole figures are measured with x-rays or neutrons using short detector scans over the center of an individual diffraction peak for a large number of different sample orientations. This is efficient if the selected diffraction peaks are reasonably strong (relative to background) and well separated, such as in pure fcc and bcc metals. It is also appropriate for constant wavelength sources where collection of individual diffraction peak intensities is a reasonably efficient use of the source. However, the traditional method is not very efficient for neutron diffraction at a spallation source such as LANSCE where the entire diffraction pattern is accessible for each sample setting. Moreover, a different approach is necessary for complicated diffraction patterns, such as from composite materials, intermetallic compounds, high T c ceramics, polyphasic minerals and polymers where there is expected to be heavy overlap of adjacent diffraction peaks. In addition, the large number of settings normally collected for an individual pole figure may not be necessary, since the entire pattern is obtained at each setting. Thus, a new method of ODF analysis needs to be developed to handle the more complex diffraction patterns obtained from modern technological materials as well as take advantage of the particular characteristics of spallation neutron sources. This project sought to develop the experimental procedures and the mathematical treatment needed to produce an orientation distribution function (ODF) directly from full diffraction patterns from a sample in a limited number of orientations

Structure and decomposition of the silver formate Ag(HCO{sub 2})

Energy Technology Data Exchange (ETDEWEB)

Puzan, Anna N., E-mail: anna_puzan@mail.ru; Baumer, Vyacheslav N.; Mateychenko, Pavel V.

2017-02-15

Crystal structure of the silver formate Ag(HCO{sub 2}) has been determined (orthorhombic, sp.gr. Pccn, a=7.1199(5), b=10.3737(4), c=6.4701(3)Å, V=477.88(4) Å{sup 3}, Z=8). The structure contains isolated formate ions and the pairs Ag{sub 2}{sup 2+} which form the layers in (001) planes (the shortest Ag–Ag distances is 2.919 in the pair and 3.421 and 3.716 Å between the nearest Ag atoms of adjacent pairs). Silver formate is unstable compound which decompose spontaneously vs time. Decomposition was studied using Rietveld analysis of the powder diffraction patterns. It was concluded that the diffusion of Ag atoms leads to the formation of plate-like metal particles as nuclei in the (100) planes which settle parallel to (001) planes of the silver formate matrix. - Highlights: • Silver formate Ag(HCO{sub 2}) was synthesized and characterized. • Layered packing of Ag-Ag pairs in the structure was found. • Decomposition of Ag(HCO{sub 2}) and formation of metal phase were studied. • Rietveld-refined micro-structural characteristics during decomposition reveal the space relationship between the matrix structure and forming Ag phase REPLACE with: Space relationship between the matrix structure and forming Ag phase.

Phase relations and crystal structures in the systems (Bi,Ln)2WO6 and (Bi,Ln)2MoO6 (Ln=lanthanide)

International Nuclear Information System (INIS)

Berdonosov, Peter S.; Charkin, Dmitri O.; Knight, Kevin S.; Johnston, Karen E.; Goff, Richard J.; Dolgikh, Valeriy A.; Lightfoot, Philip

2006-01-01

Several outstanding aspects of phase behaviour in the systems (Bi,Ln) 2 WO 6 and (Bi,Ln) 2 MoO 6 (Ln=lanthanide) have been clarified. Detailed crystal structures, from Rietveld refinement of powder neutron diffraction data, are provided for Bi 1.8 La 0.2 WO 6 (L-Bi 2 WO 6 type) and BiLaWO 6 , BiNdWO 6 , Bi 0.7 Yb 1.3 WO 6 and Bi 0.7 Yb 1.3 WO 6 (all H-Bi 2 WO 6 type). Phase evolution within the solid solution Bi 2- x La x MoO 6 has been re-examined, and a crossover from γ(H)-Bi 2 MoO 6 type to γ-R 2 MoO 6 type is observed at x∼1.2. A preliminary X-ray Rietveld refinement of the line phase BiNdMoO 6 has confirmed the α-R 2 MoO 6 type structure, with a possible partial ordering of Bi/Nd over the three crystallographically distinct R sites. - Graphical abstract: A summary of phase relations in the lanthanide-doped bismuth tungstate and bismuth molybdate systems is presented, together with some additional structural data on several of these phases

Structure and decomposition of the silver formate Ag(HCO2)

International Nuclear Information System (INIS)

Puzan, Anna N.; Baumer, Vyacheslav N.; Mateychenko, Pavel V.

2017-01-01

Crystal structure of the silver formate Ag(HCO 2 ) has been determined (orthorhombic, sp.gr. Pccn, a=7.1199(5), b=10.3737(4), c=6.4701(3)Å, V=477.88(4) Å 3 , Z=8). The structure contains isolated formate ions and the pairs Ag 2 2+ which form the layers in (001) planes (the shortest Ag–Ag distances is 2.919 in the pair and 3.421 and 3.716 Å between the nearest Ag atoms of adjacent pairs). Silver formate is unstable compound which decompose spontaneously vs time. Decomposition was studied using Rietveld analysis of the powder diffraction patterns. It was concluded that the diffusion of Ag atoms leads to the formation of plate-like metal particles as nuclei in the (100) planes which settle parallel to (001) planes of the silver formate matrix. - Highlights: • Silver formate Ag(HCO 2 ) was synthesized and characterized. • Layered packing of Ag-Ag pairs in the structure was found. • Decomposition of Ag(HCO 2 ) and formation of metal phase were studied. • Rietveld-refined micro-structural characteristics during decomposition reveal the space relationship between the matrix structure and forming Ag phase REPLACE with: Space relationship between the matrix structure and forming Ag phase.

Prioridades de conservación aplicando información filogenética y endemicidad: un ejemplo basado en Carabidae (Coleoptera de América del Sur austral Conservation priorities using phylogenetic information and endemicity: an example based on Carabid beetles from Southern South America

Directory of Open Access Journals (Sweden)

Sergio Roig-Juñent

2004-12-01

Full Text Available Sobre la base de la información distribucional de las especies de Carabidae (Coleoptera de América del Sur austral, se reconocieron 17 áreas de endemismo. Para cada una de ellas se estimó la diversidad gamma, el porcentaje de endemismo, el valor filogenético y la complementariedad, exceptuando Juan Fernández del cual no se pudo obtener ningún valor filogenético. El cálculo del valor filogenético se realizó a través del uso de cuatro índices, el valor filogenético sin ninguna modificación (W, considerando la endemicidad (We, y sus respectivas estandarizaciones (Ws y Wes. Los resultados muestran que la estandarización del valor filogenético (Ws produce un sesgo cuando los cladogramas difieren en tamaño y que el complemento entre áreas es una herramienta secundaria de gran utilidad. Sin embargo, los resultados muestran que para determinar la importancia de las áreas, el complemento debe ser usado en conjunto con la diversidad específica y la endemicidad. Las comparaciones de los resultados obtenidos usando W, We y análisis de complementariedad estrictos y modificados muestran que el valor filogenético que admite endemicidad (We puede ser aplicado como único valor para determinar la importancia de cada área. Aplicando We, las seis primeras áreas seleccionadas acumulan el 72 % del valor filogenético y el 74 % de la diversidad gamma de los carábidos de América del Sur austral, mientras que ninguno de los otros parámetros usados acumula el 70 % de las especies antes de sumar la séptima área. Las seis áreas seleccionadas son la Selva valdiviana, las Sierras pampeanas, Coquimbo, Patagonia occidental, Chile central y La Araucanía. Es de hacer notar que las Sierras pampeanas y la Patagonia occidental son ambientes de pastizales, Coquimbo y Chile central son ambientes áridos y semiáridos, y solo la Selva valdiviana y Araucanía son típicos bosques australesBased on information of the Southern South American carabid

CARACTERIZACIÓN Y EVALUACIÓN DE LA SUSTENTABILIDAD DE FINCAS EN ALTO URUBAMBA, CUSCO, PERÚ*

OpenAIRE

Merma, Isaías; Universidad Nacional San Antonio Abad del Cusco (Perú).; Julca, Alberto; Universidad Nacional Agraria La Molina (Perú).

2012-01-01

El estudio se llevó a cabo en la provincia de La Convención, Cusco – Perú, en la región geográfica de selva alta conocida como Alto Urubamba. Tiene como objetivo evaluar las características prediales y medir la sustentabilidad de fincas a través de indicadores adaptados al lugar. Se recogió información de campo tanto en términos biofísicos y socio-económicos y se analizó en variables seleccionadas, a partir de una base de datos aplicando programas como SPSS, MINITAB y Análisis Cluster. Los re...

CARACTERIZAÇÃO DE ROCHAS RESERVATÓRIO POR MICROTOMOGRAFIA DE RAIOS X

Directory of Open Access Journals (Sweden)

Leandro Palombo

2015-10-01

Este estudo propõe um procedimento para aquisição e processamento de imagens tridimensionais de amostras de rochas reservatório obtidas por MRX. A natureza 3D dos dados obtidos proporciona novas perspectivas para a avaliação da heterogeneidade das rochas e simulação do fluxo no meio poroso. A partir da análise digital de rochas, novos estudos poderão ser realizados aplicando-se a MRX como uma ferramenta para estudos de investigação sedimentológica/diagenética, caracterização da rocha reservatório e análise/modelagem de porosidade e permeabilidade.

Implementação de Cidades Inteligentes em Países em Vias de Desenvolvimento - Estudo sobre o Papel da Tecnologia no Desenvolvimento de Serviços de Cidades Inteligentes em Maputo

OpenAIRE

Gil Barroca, Jean Paulo

2015-01-01

O estudo de Cidades Inteligentes centra-se frequentemente na aplicação de tecnologias de informação e comunicação para a melhoria dos serviços urbanos e para a resolução de problemas de sustentabili-dade das cidades. Desta visão algo redutora do tema, surge literatura que apenas explora a possibilidade de implementação de soluções e estratégias de Cidades Inteligentes em países cujo contexto facilite a aplicação e adopção dessas soluções. Aplicando a visão da Cidade Inteligente que resu...

Compostaje de residuos orgánicos y de lenteja de agua (Lemna SP.) con aplicación microorganismos eficaces

OpenAIRE

Suaña Quispe, María Elena

2013-01-01

El estudio se realizó en el Departamento de Puno, Perú; en las instalaciones del laboratorio de Biología de la Facultad de Ciencias Biológicas durante los meses de Octubre a Diciembre del 2012, con el fin de elaborar compost a partir de residuos orgánicos domésticos y Lenteja de agua (Lemna spp.) aplicando microorganismos eficaces (EM) a tres dosis (0, 100 y 200 mi) se evaluó el tiempo de descomposición y granulometría, temperatura, pH, nitrógeno, fósforo, potasio y sodio. Se utilizó el análi...

Salud nutricional y saneamiento ambiental en el centro poblado menor "el milagro" de Trujillo - Perú

OpenAIRE

Aldabe Boyd, María Susana

2006-01-01

Se describe y analiza la condición de salud nutricional y de saneamiento ambiental en el Centro poblado Menor El Milagro. La muestra estuvo constituida por el 30 % (3838) de la población total de habitantes del Centro Poblado menor El Milagro, de los cuales 2,025 fueron escolares de mayores de 5 años y menores de 18 años de edad, y 1813 adultos mayores de 18 años de edad. La evaluación del estado nutricional del niño, se realizó aplicando la metodología de Waterloo, y para el caso de los...

Subcontratación en microempresas y pequeñas empresas de Baja California

Directory of Open Access Journals (Sweden)

Natanael Ramírez Angulo

2004-01-01

Full Text Available Este artículo demuestra que la subcontratación es un elemento fundamental para incrementar la competitividad de las microempresas y pequeñas empresas cuando favorece dos condiciones: 1 la generación de mayor valor agregado en sus productos, y 2 la capitalización de sus ganancias en un mayor nivel de inversión (subcontratación activa. Asimismo, aplicando un ejercicio de teoría de juegos, se discute un modelo conceptual sobre el proceso mediante el cual los beneficios se transforman en ingresos a través de una relación de subcontratación.

Eficacia de la radiofrecuencia pulsada (RFP) aplicada en la proximidad del ganglio espinal de la raíz dorsal (GD) en radiculopatía lumbar durante 120S VS 480S

OpenAIRE

Bedmar Cruz, Dolores

2016-01-01

Tesis Doctoral leída en la Universidad Rey Juan Carlos de Madrid en 2016. Directores de la Tesis: José Olarra y Carlos Goicoechea Primero comprobar si la mejoría de los índices de intensidad de dolor y calidad de vida de los pacientes a los que se le aplica la radiofrecuencia pulsada durante 8 minutos es mayor que la mejoría obtenida aplicando solo 2 minutos así como si la duración de esta mejoría es más prolongada en el tiempo. Segundo comprobar si se reduce el consumo de fármacos tras...

Necesidad de una Norma Internacional de Información Financiera para Pymes en el Perú

Directory of Open Access Journals (Sweden)

Guillermo Humire Delgado

2008-12-01

Full Text Available El proyecto de Norma Internacional de Información Financiera (NIIF para entidaes privadas restringe las normas a aplicar para entidades que no tienen responsabilidad pública en la emisión de información contable. En el Perú, desde 1994, se aplican las NIIF completas y, según nuestra opinión, se deben seguir aplicando sin tener que modificar las normas relativas a entidades privadas. Lo que debe hacerse es implementar un intenso plan de capacitación para contadores, asistentes de contabilidad y gerentes de las entidades, y asegurar así la adecuada aplicación de las NIIF completas.

Valoración económica del uso recreativo de lugares turísticos: el caso de las bahías de Santa Marta, El Rodadero y Taganga (Colombia)

OpenAIRE

Pupo García, Luis Carlos

2012-01-01

Este documento presenta la valoración económica que realizan los turistas que visitan las playas de la ciudad de Santa Marta, con base cálculos de modelos econométricos, aplicando el método de costo de viaje; el cual es empleado para estimar valores de uso económicos de ecosistemas. La investigación revela que el costo promedio diario en las bahías es de $42.969,67. Además se encontró que el 47% de los turistas consideran que se debe erradicar de la bahía el vertimiento de aguas lluvias, fact...

Una propuesta de comercialización para las exportaciones menores y nuevas con destino al mercado Japonés

Directory of Open Access Journals (Sweden)

Victoria Eugenia Orbes Algarra

2010-05-01

Full Text Available Mediante la utilización de los canales de comercialización que tienen México y Chile con el Japón, se propone promover las exportaciones de frutas, aplicando el sistema de Tercer Socio Comercial (Third Country Trade, utilizado exitosamente por las comercializadoras japonesas. En particular, la propuesta está basada en las ventajas que ofrece la complementariedad existente entre las cosechas de mango de Colombia y México, así como de las frutas exóticas entre Colombia y Chile.Una propuesta de comercialización para las exportaciones menores y nuevas con destino al mercado Japonés

Anglicisms in CREA: a Quantitative Analysis in Spanish Newspapers

OpenAIRE

Núñez Nogueroles, Eugenia Esperanza

2016-01-01

El uso de anglicismos en la lengua española hoy en día es perceptible en diversos ámbitos. En este artículo se analizará uno de ellos: la prensa contemporánea. Se realizará una búsqueda de un total de 2198 anglicismos en el Corpus de Referencia del Español Actual (CREA), aplicando filtros de fecha (2001 – 2004), medio (prensa) y localización geográfica (España). Los resultados se ordenarán de acuerdo con la fuente en la que se hayan obtenido (i.e. el periódico) para así establecer una clasifi...

Ruedas vinculantes como espacio de inclusion en el contexto universitario: la experiencia de la Universidad Estatal Amazónica, Puyo, Pastaza, Ecuador

Directory of Open Access Journals (Sweden)

Rosaura Gutiérrez Valerio de May

2016-06-01

Full Text Available En la Universidad Estatal Amazónica (UEA, en la Amazonía Ecuatoriana, se inició un programa de Desarrollo Humano Integral, aplicando la metodología de la TCI. Como primeros resultados de las Ruedas Vinculantes (término utilizado en el contexto universitario para la TCI, se presentan las apreciaciones de los participantes, que resaltan que los temas tratados les sirven como aporte para mejorar sus propios problemas, que sienten alivio y mayor autoconfianza, así como mayor confianza y solidaridad con los compañeros de curso. Esto confirma que las sesiones contribuyen a la creación de redes solidarias.

Prevalencia del virus de la hepatitis C en las unidades de hemodiálisis de la región occidental cubana

OpenAIRE

Santana Hernández, Rita Rosa; Martínez Córdova, Zuzet; Martínez Echeverría, María Teresa; Mato Luis, Jorge

2009-01-01

La población de hemodiálisis constituye un grupo de alto riesgo en el caso de la infección por el virus de la hepatitis C. Se realizó un análisis multicéntrico de la prevalencia de la infección por el virus de la hepatitis C en las unidades de diálisis de la región occidental aplicando las técnicas serológicas y moleculares, y se observó si existían diferencias significativas en cuanto a la aplicación de ambas técnicas. Se obtuvieron valores elevados de prevalencia de anticuerpos anti-VHC en ...

Acessibilidade e aglomerações na Região Norte do Brasil sob o enfoque da Nova Geografia Econômica

Directory of Open Access Journals (Sweden)

Renilson Rodrigues da Silva

2014-08-01

estimadas aplicando o método de econometria espacial. Constatou-se que os municípios mais pobres da Região Norte têm no fator isolamento geográfico um dos determinantes da sua condição econômica. As dificuldades de acesso impedem esses municípios de escoar sua produção, basicamente oriunda da agropecuária, aos mercados potenciais. Confirmou-se também que houve redução nos custos de transportes, que culminou na melhoria da acessibilidade e na formação das aglomerações populacionais.

Elaboración de una nueva línea de negocio a través del modelo CANVAS para una empresa dedicada a la agricultura de precisión

OpenAIRE

FERNÁNDEZ SANZ, ELOÍSA

2018-01-01

Para el presente trabajo de fin de grado se elaborará una nueva línea de negocio para la empresa Bynse, dedicada a la agricultura de precisión aplicando tecnología big data. Esta nueva línea de negocio consistirá en aplicar la información obtenida a través de la tecnología de la empresa a seguros agrarios. Fernández Sanz, E. (2017). Elaboración de una nueva línea de negocio a través del modelo CANVAS para una empresa dedicada a la agricultura de precisión. http://hdl.handle.net/10251/98536...

Determination of the stoichiometric rate in UO2 samples

International Nuclear Information System (INIS)

Moura, Sergio C.; Lima, Nelson B. de; Sassine, Andre; Bustillos, Jose Oscar Vega

2000-01-01

The gravimetric and voltammetric methods for determination of non-stoichiometric O/U ratio in uranium dioxide used as nuclear fuel are discussed in this work. The oxidation of uranium oxide is very complex due to many phase changes. Gravimetric and voltammetric methods do not detect phase changes. The results of this work shown that, to evaluate both methods is requiring to be done Rietveld methods by X-ray diffraction data to identify the uranium oxide phase changes. (author)

Study of non stoichiometric uranium dioxide samples (UO2)

International Nuclear Information System (INIS)

Moura, Sergio C.; Lima, Nelson B. de; Bustillos, Jose O.V.

1999-01-01

The gravimetric and voltammetric methods for determination of non-stoichiometric O/U ratio in uranium dioxide used as nuclear fuel are discussed in this work. The oxidation of uranium oxide is very complex due to many phase changes. gravimetric and voltammetric methods do not detect phase changes. The results of this work shown that, to evaluate both methods is requiring to be done Rietveld methods by x-ray diffraction data to identify the uranium oxide phase changes. (author)

Compaction of lithium-silicate ceramics using spark plasma sintering

Czech Academy of Sciences Publication Activity Database

Kubatík, Tomáš František; Lukáč, František; Mušálek, Radek; Brožek, Vlastimil; Stehlíková, K.; Chráska, Tomáš

2017-01-01

Roč. 61, č. 1 (2017), s. 40-44 ISSN 0862-5468 R&D Projects: GA ČR GB14-36566G Institutional support: RVO:61389021 Keywords : Li2Si2O5 * Li2SiO3 * Spark plasma sintering (SPS) * Quantitative Rietveld refinement * X-ray diffraction (XRD) Subject RIV: JG - Metallurgy OBOR OECD: Materials engineering Impact factor: 0.439, year: 2016 http://www.ceramics-silikaty.cz/index.php?page=cs_detail_doi&id=789

Neutron powder diffraction studies of Hydrogen and Denterium in Palladium Phosphides

International Nuclear Information System (INIS)

Andersson, Y.

1986-01-01

The use of the Rietveld-type profile refinements on neutron powder diffraction intensity data for determining crystallographic positions of hydrogen and deuterium in metal hydrides is illustrated by results obtained on some hydrogenated and deuterated palladium phosphides. The structural features of the solid solutions of hydrogen and deuterium in Pd/sb15/P/sb2/ Pd/sb6/P and Pd/sb3/P/sb1-u/ (0< u<0.28) are briefly presented and discussed

Modelling of critical functions of nuclear reactors using Fild Programmable Gate Array; Modelagem de funcoes criticas de reatores nucleares utilizando Fild Programmable Gate Array

Energy Technology Data Exchange (ETDEWEB)

Teixeira, Pamela Iara Nolasco

2016-07-01

This paper proposes the development of a method using FPGA for critical security functions of a nuclear reactor. It was implemented two critical safety functions in VHDL, which is a way to describe, through a program, the behavior of a circuit or digital component. Two critical security functions, FCS Core Cooling, responsible for cooling the reactor core in the charts of the plant and also in the event of accidents involving loss of coolant and FCS Heat Transfer, responsible for cooling the reactor core in the event an accident with loss of coolant were implemented. In this Dissertation it was chosen the use of FPGA, because - due to the effects of aging, obsolescence issues, environmental degradation and mechanical failures - nuclear power plants need to replace their older systems by new ones based on digital technology. The technologies obtained using a system described in hardware language can be implemented in a programmable device, having the advantage of changing the code at any time. (author)

Influence of milling time on microstructure and magnetic properties of Fe{sub 80}P{sub 11}C{sub 9} alloy produced by mechanical alloying

Energy Technology Data Exchange (ETDEWEB)

Taghvaei, A.H. [Department of Materials Science and Engineering, Shiraz University of Technology, Shiraz (Iran, Islamic Republic of); Ghajari, F., E-mail: fati.ghajari@gmail.com [Department of Materials Science and Engineering, Shiraz University, Shiraz (Iran, Islamic Republic of); Markó, D. [IFW Dresden, Institute for Complex Materials, Helmholtzstr. 20, 01069 Dresden (Germany); Prashanth, K.G. [IFW Dresden, Institute for Complex Materials, Helmholtzstr. 20, 01069 Dresden (Germany); Additive manufacturing Center, Sandvik AB, 81181 Sandviken (Sweden)

2015-12-01

Fe{sub 80}P{sub 11}C{sub 9} alloy with amorphous/nanocrytalline microstructure has been synthesized by mechanical alloying of the elemental powders. The microstructure, thermal behavior and morphology of the produced powders have been studied by X-ray diffraction (XRD), differential scanning calorimetry (DSC) and scanning electron microscopy (SEM), respectively. The crystallite size, lattice strain and fraction of the amorphous phase have been calculated by Rietveld refinement method. The results indicate that the powders microstructure consists of α-Fe(P,C) nanocrystals with an average diameter of 9 nm±1 nm dispersed in the amorphous matrix after 90 h of milling. Moreover, the fraction of amorphous phase initially increases up to 90 h of milling and then decreases after 120 h of milling, as a result of mechanical crystallization and formation of Fe{sub 2}P phase. The magnetic measurements show that while the saturation magnetization decreases continuously with the milling time, the coercivity exhibits a complicated trend. The correlation between microstructural changes and magnetic properties has been discussed in detail. - Highlights: • Glass formation was investigated in Fe{sub 80}P{sub 11}C{sub 9} by mechanical alloying. • Structural parameters were calculated by Rietveld refinement method. • Milling first increased and then decreased the fraction of amorphous phase. • Magnetic properties were significantly changed upon milling.

Understanding the formation and growth of Ag nanoparticles on silver chromate induced by electron irradiation in electron microscope: A combined experimental and theoretical study

International Nuclear Information System (INIS)

Fabbro, Maria T.; Gracia, Lourdes; Silva, Gabriela S.; Santos, Luís P.S.; Andrés, Juan; Cordoncillo, Eloisa; Longo, E.

2016-01-01

Ag 2 CrO 4 microcrystals were synthesized using the co-precipitation method. These microcrystals were characterized through X-ray diffraction (XRD) with Rietveld analysis, field-emission scanning electron microscopy (FE-SEM), transmission electron microscopy (TEM) with energy-dispersive spectroscopy (EDS), micro-Raman (MR). XRD patterns and Rietveld refinement data showed that the material exhibits an orthorhombic structure without any deleterious phases. FE-SEM and TEM micrographs revealed the morphology and the growth of Ag nanoparticles on Ag 2 CrO 4 microcrystals during electron beam irradiation. These events were directly monitored in real-time. Their optical properties were investigated using ultraviolet-visible (UV–vis) diffuse reflectance spectroscopy that allowed the calculation of the optical band gap energy. Theoretical analyses based on the density functional theory level indicate that the incorporation of electrons is responsible for structural modifications and formation of defects on the [AgO 6 ] and [AgO 4 ] clusters, generating ideal conditions for the growth of Ag nanoparticles. - Graphical abstract: Theoretical representation of the Ag 2 CrO 4 orthorhombic structure. Display Omitted - Highlights: • The Ag 2 CrO 4 microcrystals indicate an orthorhombic structure. • The formation of Ag 0 promotes Ag-nanoparticle growth on the surface of the Ag 2 CrO 4 . • Electron irradiation of the material induces the formation of Ag vacancies.

Effect of laser irradiation on Ag4In12Sb56Te28

Science.gov (United States)

Chinnusamy, Rangasami

2018-04-01

Ag4In12Sb56Te28 has been synthesized by melt-quench method. Phase homogeneity, crystal structure and effect of laser irradiation have been investigated using X-ray diffraction (XRD) and Raman spectroscopy. Rietveld refinement of crystal structure revealed that Ag4In12Sb56Te28 is a multiphase system with AgIn3Te5, Sb8Te3 and Sb phases. Combined optical microscopy and Raman spectroscopy have been used to understand the distribution of different phases on the surface of the samples, which substantiated the results of Rietveld analysis. Interaction of 20 mW laser beam with samples has been investigated using Raman measurements. The results have shown that regions with large phase fraction of AgIn3Te5 become amorphous during laser-sample interaction, but the starting phase remains nearly same after the interaction. Regions with AgIn3Te5 and nearly equal or larger amount of Sb8Te3 have shown significant growth of α-Sb2O3 during and after laser-sample interaction. Regions rich in Sb have shown formation of AgIn3Te5 and growth of α-Sb2O3 during and after interaction. These observations have been explained based on the maximum temperature rise at different regions during laser-sample interaction.

Deriving Quantitative Crystallographic Information from the Wavelength-Resolved Neutron Transmission Analysis Performed in Imaging Mode

Directory of Open Access Journals (Sweden)

Hirotaka Sato

2017-12-01

Full Text Available Current status of Bragg-edge/dip neutron transmission analysis/imaging methods is presented. The method can visualize real-space distributions of bulk crystallographic information in a crystalline material over a large area (~10 cm with high spatial resolution (~100 μm. Furthermore, by using suitable spectrum analysis methods for wavelength-dependent neutron transmission data, quantitative visualization of the crystallographic information can be achieved. For example, crystallographic texture imaging, crystallite size imaging and crystalline phase imaging with texture/extinction corrections are carried out by the Rietveld-type (wide wavelength bandwidth profile fitting analysis code, RITS (Rietveld Imaging of Transmission Spectra. By using the single Bragg-edge analysis mode of RITS, evaluations of crystal lattice plane spacing (d-spacing relating to macro-strain and d-spacing distribution’s FWHM (full width at half maximum relating to micro-strain can be achieved. Macro-strain tomography is performed by a new conceptual CT (computed tomography image reconstruction algorithm, the tensor CT method. Crystalline grains and their orientations are visualized by a fast determination method of grain orientation for Bragg-dip neutron transmission spectrum. In this paper, these imaging examples with the spectrum analysis methods and the reliabilities evaluated by optical/electron microscope and X-ray/neutron diffraction, are presented. In addition, the status at compact accelerator driven pulsed neutron sources is also presented.

Room temperature neutron diffraction and magnetic studies of multiferroic Pb{sub 0.9}Bi{sub 0.1}Fe{sub 0.55}Nb{sub 0.45}O{sub 3} solid solution

Energy Technology Data Exchange (ETDEWEB)

Dadami, S. T.; Matteppanavar, S.; Shivaraja, I.; Angadi, B., E-mail: brangadi@gmail.com [Department of Physics, Bangalore University, Bangalore-560056 (India); Rayaprol, S.; Deshpande, S. K. [UGC-DAE-CSR, Mumbai Centre, BARC, Mumbai-400085 (India)

2016-05-23

The Pb{sub 0.9}Bi{sub 0.1}Fe{sub 0.55}Nb{sub 0.45}O{sub 3} (PBFNO) solid solution was synthesized by single step solid state reaction method and the optimized parameters are 700°C for 2hr (calcination) and 800°C for 3hr (sintering). The formation of desired material was confirmed using X-Ray Diffraction (XRD) and Neutron Diffraction (ND) studies. The structural and magnetic properties of the sintered pellets were investigated at room temperature (RT) through XRD, ND and Magnetic (M-H) studies. The structural analysis was carried out by Rietveld refinement through the Full Prof program. Rietveld refined XRD and ND patterns confirms the monoclinic structure with Cm space group and obtained cell parameters from the ND data are a = 5.651(2) Å, b = 5.658(2) Å, c = 4.005(1) Å and α = 90°, β = 89.98(1)°, γ = 90°. RT M-H curve studies have been carried out. It shows the clear opening of hysteresis (M–H) loop, is evidenced as the existence of weak ferromagnetism at RT. The M-H data shows existence weak ferromagnetism embedded in an antiferromagnetic matrix structure. The dielectric constant with frequency shows the formation of barrier layers at the grain and grain boundary interfaces gives rise to interfacial space charge polarization.

Aplicando la Metodología PSP para el Desarrollo de un Sistema de Reconocimiento de Gestos

Directory of Open Access Journals (Sweden)

Erik Ramos Pérez

2015-12-01

Full Text Available MUDI es un sistema reconocedor de gestos, capaz de detectar el acercamiento, rotación y cambiar de pieza arqueológica modeladas en 3D existentes en el MureH. El sistema está contextualizado para un museo interactivo en el que los usuarios puedan descubrir las características de las piezas de una forma entretenida y divertida. Para desarrollar el sistema se utilizó PSP, el cual es una metodología encaminada al proceso personal, establecido y regido por etapas bien establecidas, una de ellas es el diseño que permite tener una buena estructura del sistema traduciéndose en una fácil implementación y control de los errores de codificación, así como el manejo de los requerimientos. Para medir la interacción, efectividad y facilidad de uso de MUDI se usaron técnicas de usabilidad, obteniendo resultados favorables, específicamente el acercamiento tuvo una calificación de 4.8, rotación de 4.0 y cambiar pieza de 4.4 en una escala del 0 al 5. Los usuarios manifestaron gran aceptación y buenos comentarios puesto que con MUDI se olvidaban de las visitas tradicionales.

Obtención de carmín de cochinilla aplicando hidrólisis enzimática

OpenAIRE

Inga Cueva, Tula Norma; Inga Cueva, Tula Norma

2012-01-01

El consumo de colorantes sintéticos como aditivos en la industria alimentaria, está siendo cada vez restringido, por las entidades reguladoras en aseguramiento, saneamiento en alimentos, debido a sus efectos toxicológicos, entre los que se encuentra el colorante rojo sintético azoico FD&C Red No. 2, conocido como Amaranto o E 123, (código alimentario según la Unión Europea), utilizados para dar color rojo a alimentos y cosméticos, siendo prohibido su consumo desde 1976 por la Administración d...

Optimización de la Gestión de Recursos Humanos (GRH) aplicando las soluciones SAP.

OpenAIRE

Arribas Martinez, Montserrat Ana

2017-01-01

Transformation of the HR function through technologies such as SAP HCM that facilitates the configuration of shared service centers (centralization) and which favors the digital transformation of their employees. Transformación de la Función de Recursos Humans mediante tecnología SAP HCM que facilita la configuración de centros de servicio compartidos (centralitzación) y que favorece la transformación digital de sus empleados. Transformació de la Funció de Recursos Humans mitjançant tec...

Aplicando instrumentos metodológicos: alimentación en hogares urbanos de S. S. de Jujuy

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Quintana, Sonia B.

2005-01-01

Full Text Available En el marco del proyecto "Auxología humana, nivel socioeconómico familiar y hábitos alimentarios en Jujuy (Argentina" y luego de estimar con técnicas antropométricas el estado nutricional de los alumnos concurrentes a la escuela Nº 430 del Barrio Norte de la capital jujeña, decidimos profundizar la investigación, buscando la interrelación con aspectos socioeconómicos y efectivas prácticas alimentarias. Para cumplir con este objetivo, recurrimos a instrumentos y técnicas de investigación que metodológicamente dieran cuenta de la complejidad del fenómeno. De este modo, se realizaron -en hogares seleccionados- entrevistas semiestructuradas dirigidas principalmente a aspectos sociodemográficos y socioeconómicos, y a continuación se aplicó anamnesis alimentaria a los/as encargados/as de la alimentación familiar. Luego del diseño, se efectuaron dos pruebas piloto, con la correspondiente adecuación de los instrumentos, surgiendo: a la conveniencia de aplicar primero la entrevista para facilitar el diálogo con el informante, y luego la encuesta al permitir repreguntar y corroborar respuestas antes dadas; y b la importancia de tener en cuenta la representación que el informante construye de su interlocutor y el rol que le asigna.

Generación de un geoportal con análisis espacial aplicando operaciones geométricas

OpenAIRE

Torre Gordón, Nelson David de la

2017-01-01

The present project seeks to apply the acquired knowledge for the construction of a GeoPortal that allows basic geometric operations with spatial data stored in any previously loaded database. Selection of information is dynamic, allowing to assemble queries so finally encoded in GeoJSON format that can be copied or transmitted to another system in a light and fast way. In the first chapter is the theoretical framework necessary for understanding the construction of the GeoPortal. In...

Firework Madness: aplicando los métodos de un ingeniero de software al desarrollo de videojuegos

OpenAIRE

Pérez Alonso, Rubén

2016-01-01

Este trabajo se basa en la aplicación de métodos de desarrollo estructurado de software aprendidos durante la carrera en el ámbito del desarrollo de videojuegos, el cual por su juventud escasea de éstos. Idioma castellano.

Quantitative study of Portland cement hydration by X-Ray diffraction/Rietveld analysis and geochemical modeling

Science.gov (United States)

Coutelot, F.; Seaman, J. C.; Simner, S.

2017-12-01

In this study the hydration of Portland cements containing blast-furnace slag and type V fly ash were investigated during cement curing using X-ray diffraction, with geochemical modeling used to calculate the total volume of hydrates. The goal was to evaluate the relationship between the starting component levels and the hydrate assemblages that develop during the curing process. Blast furnace-slag levels of 60, 45 and 30 wt.% were studied in blends containing fly ash and Portland cement. Geochemical modelling described the dissolution of the clinker, and predicted quantitatively the amount of hydrates. In all cases the experiments showed the presence of C-S-H, portlandite and ettringite. The quantities of ettringite, portlandite and the amorphous phases as determined by XRD agreed well with the calculated amounts of these phases after different periods of time. These findings show that changes in the bulk composition of hydrating cements can be described by geochemical models. Such a comparison between experimental and modelled data helps to understand in more detail the active processes occurring during cement hydration.

Structural characterization of two new quaternary chalcogenides: CuCo{sub 2}InTe{sub 4} and CuNi{sub 2}InTe{sub 4}

Energy Technology Data Exchange (ETDEWEB)

Delgado, Gerzon E.; Grima-Gallardo, Pedro; Nieves, Luis, E-mail: gerzon@ula.ve [Universidad de Los Andes, Merida (Venezuela, Bolivarian Republic of); Cabrera, Humberto [Centro Multidisciplinario de Ciencias, Instituto Venezolano de Investigaciones Cientificas (IVIC), Merida (Venezuela, Bolivarian Republic of); Glenn, Jennifer R.; Aitken, Jennifer A. [Department of Chemistry and Biochemistry, Duquesne University, Pittsburgh, PA (United States)

2016-11-15

The crystal structure of the chalcogenide compounds CuCo{sub 2}InTe{sub 4} and CuNi{sub 2}InTe{sub 4} , two new members of the I-II{sub 2}-III-VI{sub 4} family, were characterized by Rietveld refinement using X-ray powder diffraction data. Both materials crystallize in the tetragonal space group I4-bar 2m (No. 121), Z = 2, with a stannite-type structure, with the binaries CoTe and NiTe as secondary phases. (author)

Site-selective fluorescence spectroscopy investigations of LnPO{sub 4} xenotime ceramics for radioactive waste disposal

Energy Technology Data Exchange (ETDEWEB)

Hirsch, A.; Peters, L. [RWTH Aachen Univ. (Germany). Inst. of Crystallography; Holthausen, J.; Neumeier, S. [Forschungszentrum Juelich (Germany); Huittinen, Nina [Helmholtz-Zentrum Dresden-Rossendorf e.V., Dresden (Germany). Surface Processes; Loesch, Henry

2017-06-01

Europium incorporation in different LnPO{sub 4} (Ln=Tb, Lu and Gd{sub 1-x}Lu{sub x}) phases crystallizing in the xenotime structure was investigated with site-selective TRLFS, PXRD and Rietveld analyses. Based on recorded emission spectra and diffraction patterns, the formation of three different crystal systems (xenotime, anhydrite, and monazite) could be identified. Aging of the ceramic samples and a second sintering step led to an accumulation of europium in the grain boundaries and on the surface.

Synthesis and characterization of nanosized ceria powders by microwave-hydrothermal method

International Nuclear Information System (INIS)

Bonamartini Corradi, A.; Bondioli, F.; Ferrari, A.M.; Manfredini, T.

2006-01-01

Nanocrystalline ceria powders (CeO 2 ) have been prepared by adding NaOH to a cerium ammonium nitrate aqueous solution under microwave-hydrothermal conditions. In particular the effect of the synthesis conditions (time, pressure and concentration of both the precursor and the precipitant agent solutions) on the physical properties of the crystals have been evaluated. Microwave-hydrothermal treatment of 5 min at 13.4 atm allows to obtain almost crystallized powders (amorphous phase 4%) as underlined by Rietveld-reference intensity ratio (RIR) results

Characterization of UO22+ exchanged Y zeolite

International Nuclear Information System (INIS)

Olguin, M.T.; Bosch, P.; Bulbulian, S.; Duque, J.; Pomes, R.; Villafuerte-Castrejon, M.E.; Sansores, L.E.; Bosch, P.

1997-01-01

The present study discusses the incorporation of uranyl ion into Y-zeolite framework. The UO 2 2+ sorption was measured by neutron activation analyses. The Y-zeolite framework distorts in response to the cations present in the structure. Hence, depending on the amount and the location of the exchanged cations, the features of the X-ray diffraction pattern may vary. From the Rietveld analysis of these patterns, the positions occupied by the UO 2 2 + cations in the zeolite network were determined. (author)

VALORACIÓN GERIÁTRICA DE ANCIANOS DE MUY BAJOS RECURSOS SOCIO-ECONÓMICOS EN LA ARGENTINA

Directory of Open Access Journals (Sweden)

José Ricardo Jáuregui

2011-01-01

Full Text Available Objetivos: Describir el estado funcional, socio-económico y la situación ambiental de una población muy pobre de ancianos (mayores de 65 años de Argentina, y su relación con su autonomía. Métodos: Se trata de un estudio descriptivo y prospectivo. El instrumento empleado fue la escala de la Cruz Roja en español. La evaluación arriba mencionada fue completada aplicando un segundo instrumento para evaluación social descripto por Marin y colaboradores en Chile en 1994. Además, se recolectó información general de la población estudiada, como: condiciones ambientales, familiares y sociales. La comparación estadística se realizó mediante prueba de Chi-cuadrado, mientras que el test de Student o un test no paramétrico fue empleado según la distribución de los datos. Resultado: De una muetra de 219 personas, con una edad media 69 ± 6 años, se obtuvo la evaluación funcional de cada uno de ellos aplicando la escala de la Cruz Roja, clasificando los datos según la edad (mayor o menor de 75 años, educación, ingreso económico y género. No se hallo diferencia estadísticamente significativa entre los grupos etareos comparados, en ninguna de las escalas aplicadas (p=NS, ANOVA-Bonferroni. Conclusion: No se hallo diferencia estadísticamente significativa entre las personas estudiadas ni en los estados funcionales, habilidad para realizar tareas de la vida diaria, ni estado cognitivo en función de su edad, género, nivel educativo y económico.

GROSOR DEL FRUTO DE LA ÚLTIMA Y SEGUNDA MANO COMO CRITERIO DE COSECHA EN BANANO

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Alfonso Vargas-Calvo

2012-01-01

Full Text Available Grosor del fruto de la última y segunda mano como criterio de cosecha en banano. El objetivo de este trabajo fue determinar la relación entre el grosor del fruto central de las manos última y segunda, como criterio de cosecha en el banano. Las mediciones se efectuaron semanalmente (mm de la segunda a la décima semana después de la fl oración y fueron transformadas a treintaidosavos de pulgada (tdp donde 1 tdp= 0,7914 mm, para la generación de ecuaciones de regresión para ambas manos, considerando, o ignorando, el tamaño del racimo. El grosor del fruto central de la última mano fue estimado a partir del grosor del fruto central de la segunda mano, y viceversa para el grosor del fruto de la segunda mano. Los valores de grosor del fruto central de la última mano (valores Y obtenidos aplicando los grosores mínimos preestablecidos de cosecha para el fruto central de la segunda mano (valores x: 43; 44 y 45 tdp fueron superiores a 40 tdp, independientemente del tamaño del racimo, e inclusive superó en la mayoría de las veces, a 41 tdp. Inversamente, aplicando los valores mínimos de grosor de la última mano, predefi nidos para la cosecha (valores x: 39; 40 y 41 tdp, se obtuvieron valores de grosor del fruto central de la segunda mano (valores Y, que no superaron el valor de 43 tdp excepto para x=41 en los racimos de siete a nueve manos. Los racimos cosechados con la exigencia mínima de empaque aplicada para la última mano, tuvieron menos peso, por estar conformados de frutos con menor grosor, que aquellos que se cosecharían mediante la medición en la segunda mano.

Otra forma de evaluar: Análisis de resultados.

Directory of Open Access Journals (Sweden)

Segovia González, Mª Manuela

2007-01-01

Full Text Available Desde el curso 2002-2003 se viene aplicando en la asignatura de Matemáticas de primer curso de la Diplomatura de Ciencias Empresariales en la Universidad Pablo de Olavide un método de evaluación especial (llamado Plan de Calidad debido al elevado número de no presentados y suspensos en la citada asignatura.En la primera parte de este trabajo se describe el método de evaluación aplicado y la innovación docente que se ha hecho en la asignatura. En la segunda parte se ha realizado un análisis para ver si con esta nueva metodología los resultados obtenidos por los alumnos son mejores.

Quantitative analysis by X ray fluorescence

Directory of Open Access Journals (Sweden)

Sagrera, José Luis

1966-06-01

Full Text Available Not availableSe describe en el presente trabajo el método operatorio para realizar un análisis cuantitativo rutinario de muestras naturales en estado pulverulento, determinando sus contenidos en calcio, silicio, aluminio, hierro, azufre y magnesio, expresados, todos ellos, en forma de óxidos. Dentro de la misma publicación se hace referencia a trabajos en los cuales se explican teórica y prácticamente, los procedimientos de preparación de muestras para el análisis de rayos X y eliminación de interferencias, aplicando la discriminación por altura de impulsos. Las ventajas del método se especifican en un apartado del presente trabajo.

Estimativa do potencial de degradação do solo antes e depois de um grande incêndio florestal numa bacia elementar de Alfândega da Fé

OpenAIRE

Costa, Rui; Figueiredo, Tomás de; Fonseca, Felícia

2016-01-01

Os grandes incêndios florestais expõem o solo, em extensas áreas e por largo tempo, à degradação por erosão hídrica. O local de estudo, uma pequena bacia elementar em Alfândega da Fé, NE Portugal, apresenta ainda marcas do grande incêndio de Picões (Julho de 2013), que afetou cerca de 14000 ha. Este trabalho propos-se, através da avaliação das caraterísticas biofísicas e morfológicas da bacia e aplicando o modelo de erosão USLE (Equação Universal de Perda de Solo), estimar o risco potencial d...

Unidades de transformación multifuncional: un reto del futuro próximo en el desarrollo de la ingeniería química

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Luis M. Carballo

1997-01-01

Full Text Available Las unidades de transformación multifuncional se han convertido, en años recientes, en un nuevo paradigma dentro de La Ingeniería Química. Aplicando el principio fundamental de remoción selectiva de productos, estas técnicas han permitido obtener beneficios extraordinarios en cuanto a conversión de reactantes, calidad de productos, ahorros de energía y disminución del impacto ambiental causado por algunos procesos. En el presente documento se efectúa una breve discusión de los principios que fundamentan algunos de tales procesos de transformación y se ilustran, igualmente, algunas aplicaciones actuales y futuras.

Luces entre sombras de la Orientación

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Benito Echeverría Samanes

2015-01-01

Full Text Available El papel estratégico que desempeña la orientación permanente en el triángulo educacion‐formacion‐empleo obliga a reconsiderar la viabilidad y sentido de los muchos y variados tipos de intervención desarrollados hasta ahora. El monográfico ofrece una muestra patente de algunas de ellas, resumidas en este artículo. Tras analizarlas, los autores plantean la necesidad de un Sistema Integrado de Información y Orientación (SIO capaz de poner orden, interrelacionar y conjuntar múltiples iniciativas desperdigadas, que podrían ser más funcionales, eficientes y eficaces, aplicando el principio de “más vale sumar que restar”.

mediante aprendizaje de maquina con interfaz a usuario

Directory of Open Access Journals (Sweden)

Leonardo Ramírez López

2006-01-01

Full Text Available Este trabajo presenta el desarrollo de un modelo de clasificación de arritmias cardiacas, basado en la duración de las ondas de registros electrocardiográficos, utilizando técnicas de clasificación supervisada. Los clasificadores desarrollados se basaron en técnicas de aprendizaje de máquina, Se implementaron metaclasificadores para los diferentes clasificadores. El desempeño de los diferentes clasificadores se probó aplicando criterios objetivos de comparación, y se obtuvieron resultados prometedores. Para presentar los resultados al usuario final, se diseñó una interfaz para ser usada por el especialista como ayuda a la clasificación de arritmias.

Evaluación de un modelo de formación inicial de profesores para su adaptación al EEES. Incidencia del Portafolio

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María Luisa OLIVERAS CONTRERAS

2012-01-01

Full Text Available Tras la elaboración de un Programa innovador para adecuar un curso de enseñanza universitaria, de Formación Inicial de Maestros, al EEES, aplicando nuestro Modelo Didáctico Emergente, MED, que incluye nuevas metodologías y tareas de aprendizaje para lograr nuevos objetivos, mostramos parte de los resultados de investigación, relativos a la evaluación del MED por un grupo de alumnos que participó en la aplicación del modelo. La metodología es cualitativa, incluyendo datos cuantitativos. Los resultados indican éxito del MED para las competencias profesionales: profesional reflexivo, trabajo cooperativo y creatividad interdisciplinar, objetivos para la integración del EEES.

A new method of Debye-Scherrer pattern integration on two-dimensional detectors, demonstrated for the new structure powder diffractometer (SPODI) at the FRM-II in Garching

CERN Document Server

Elf, F; Artus, G R J; Roth, S

2002-01-01

The expected diffraction patterns of the new powder diffractometer SPODI, currently under construction at the FRM-II in Garching, will be smeared Debye-Scherrer rings as depicted by Monte Carlo (MC) simulations. To overcome this disadvantage, a concept based on the combination of MC simulations and empirical approximation methods is developed to reverse the smearing by deconvolution and then summing up along the rings, including corrections for different arc lengths, resulting in conventional one-dimensional diffraction patterns suitable for Rietveld-refinement programs without further processing. (orig.)

Preparation and X-ray diffraction characterization of Th1-xBixO2-0.5x (where x= 0 to 0.5) solid solutions

International Nuclear Information System (INIS)

Kanrar, Buddhadev; Misra, N.L.

2015-01-01

Solid solutions of ThO 2 and Bi 2 O 3 were prepared by solid state reactions of these oxides. X-ray diffraction studies indicated that Bi +3 up to 50 at% can be dissolved in ThO 2 lattice. Rietveld refinement of the XRD patterns indicated single phase solid solutions up to 50 atom% of Bi +3 in ThO 2 lattice. The cell parameters of the solid solutions were found to decrease with increasing amount of Bi +3 in the lattice. (author)

Mechanism of superconductivity in Yb sub 1 sub - sub x Ca sub x (Ba sub 0 sub . sub 8 Sr sub O sub . sub 2) sub 2 Cu sub 3 O sub 6 sub + subdelta

CERN Document Server

Anvekar, T S; Sarode, P R; Kamat-Dalal, V N; Narlikar, Anant V

2002-01-01

EXAFS, X-ray Rietveld refinement and infra-red absorption measurements have been made on Yb sub 1 sub - sub x Ca sub x (Ba sub 0 sub . sub 8 Sr sub 0 sub . sub 2) sub 2 Cu sub 3 O sub 6 sub + subdelta in order to understand the effect of Ca doping on the local structure of planar Cu ion. The study indicates that restoration of superconductivity is due to oxidation of copper ions in the CuO sub 2 planes. (author)

Solid-state structural properties of 2,4,6-trimethoxybenzene derivatives, determined directly from powder X-ray diffraction data in conjunction with other techniques

International Nuclear Information System (INIS)

Pan Zhigang; Xu Mingcan; Cheung, Eugene Y.; Platts, James A.; Harris, Kenneth D.M.; Constable, Edwin C.; Housecroft, Catherine E.

2006-01-01

Structural properties of 2,4,6-trimethoxybenzaldehyde, 2,4,6-trimethoxybenzyl alcohol and 2,4,6-trimethoxyacetophenone have been determined directly from powder X-ray diffraction data, using the direct-space Genetic Algorithm (GA) technique for structure solution followed by Rietveld refinement. Structural similarities and contrasts within this family of materials are elucidated. The work illustrates the value of utilizing information from other sources, including spectroscopic data and computational techniques, as a means of augmenting the structural knowledge established from the powder X-ray diffraction data

Smaller calcite lattice deformation caused by occluded organic material in coccoliths than in mollusk shell

DEFF Research Database (Denmark)

Frølich, Simon; Sørensen, Henning Osholm; Hakim, Sepideh Sadat

2015-01-01

The growth and nucleation of biominerals are directed and affected by associated biological molecules. In this paper, we investigate the influence of occluded biomolecules on biogenic calcite from the coccolithophorid Pleurochrysis carterae and from chalk, a rock composed predominantly of fossil....... Two heating cycles allow us to differentiate the effects of thermal agitation and organic molecules. Single peak analysis and Rietveld refinement were combined to show significant differences resulting from the occluded biomolecules on the mineral phase in biogenic calcite in the mollusk shell...

Structure of Pigment Yellow 181 dimethylsulfoxide N-methyl-2-pyrrolidone (1:1:1) solvate from XRPD plus DFT-D

DEFF Research Database (Denmark)

van de Streek, Jacco

2015-01-01

With only a 2.6 Å resolution laboratory powder diffraction pattern of the phase of Pigment Yellow 181 (P.Y. 181) available, crystal-structure solution and Rietveld refinement proved challenging; especially when the crystal structure was shown to be a triclinic dimethylsulfoxide N-methyl-2...... of commercial interest, additional experiments were not economically feasible and additional dispersion-corrected density functional theory (DFT-D) calculations were employed to confirm the correctness of the crystal structure. After the correctness of the structure had been ascertained, the bond lengths...

Application of compartmental metabolic models for determination of retention and excretion functions; Aplicacao de modelos metabolicos para a determinacao de funcoes de excrecao e retencao

Energy Technology Data Exchange (ETDEWEB)

Rodrigues, Junior, O

1994-07-01

After an intake of radioactive material, its behaviour in the human body can be described by mathematical models, where organs, tissues or regions of the body are treated as a chain of linked compartments. The mathematical approach for such metabolic models is usually done through a system of differential equations of first order with constant coefficients. The solutions of this system of equations associates the radionuclide intake, with the fraction excreted or retained in the organ of interest. A computer program - called INCORP and for running in PC compatible microcomputers - was developed in order to find the solutions of such system of equations, using an analytical method based on expansion of series of exponential matrices. The metabolic model presented in the ICRP-30 publication was simulated using the INCORP program, in order to find the respective retention and excretion curves for selected radionuclides. (author)

Anomalies in Ward identities revisited. Explicit calculation of the three point functions; Anomalias em identidades de Ward revisitadas. Calculo explicito das funcoes de tres pontos

Energy Technology Data Exchange (ETDEWEB)

Dalmolin, Fabricio Tronco

2007-07-01

The occurrence of unavoidable violations in symmetry properties of physical amplitudes is certainly one of the most intriguing problems in the context of Quantum Field Theory (QFT). These violations, which are called anomalies, play a crucial role in the construction of such theories due to the requirement of renormalizability. These phenomena can be established through very general mathematical arguments which are valid also for eventual exact solutions of the associated equations of motion. Exact exact solutions, however, are rarely possible, in this context. Given this limitation, the explicit verification of the violations in symmetry properties of physical amplitudes needs to be done within the context of perturbative solutions. The complication of this task is the occurrence of divergences in the perturbative physical amplitudes and all well known problems such as ambiguities associated to the internal momenta routing in loops, which, due to the divergence degree involved, invariably plague the anomalous amplitudes. Due to this fact, anomalies are commonly presented in the literature in a way associated to the referred ambiguities. This traditional association has been questioned in the light of a new strategy for manipulations and calculations involving divergent amplitudes in QFT. Within the context of the referred technique the mentioned ambiguities can be consistently eliminated and all the amplitudes of all the theories and models are dealt in an identical way. The symmetry properties, of non anomalous amplitudes, are simultaneously satisfied for the consistently regularized (ambiguities free) version of the amplitudes. It is also possible to obtain an adequate description of the anomalous amplitudes in a simultaneous way, i.e., by using absolutely the same prescription adopted for the treatment of those non anomalous, which we will show in details along the present work. The investigation which we will report here, in certain sense are complementary to others already performed within the same issue. In particular, in one of such investigation a pioneer and traditional reference has been revisited by using the alternative strategy mentioned above. In such study, a systematic treatment of purely fermionic one, two and three point functions, associated to scalar, pseudo-scalar, vector and axial-vector densities, has done. There, however, only the explicit expressions for one and two point functions were developed. The conclusions pointed out, in a very clear way, that the association between intrinsic ambiguities of the perturbative calculation and violations in symmetry properties is not consistent. At the same time, it was concluded that only in an investigation where the explicit forms for the three point functions involved are considered clean and sound conclusions can be extracted. This is due to the fact that, in the relevant symmetry properties, it is involved three ward identities and a low energy limit. This is precisely the main purpose of the present work: to promote a detailed investigation of the relations among green functions and ward identities, within the context of a model having only one specie of 1/2 spin fermionic field, that consider all the amplitudes having superficial degree of divergence higher than the logarithmic one, in a similar way as that made in the work of Gerstein and Jackiw, taking however the explicit form for the three point functions. This is one to get in the analysis, simultaneously, the ward identities and the low energy limits involved in the anomalous amplitudes as required by the Sutherland-Veltman theorem, in order to get an adequate understanding of the anomaly phenomena. We will show that our final results can be mapped in those found with the use of the Dimensional Regularization, in situation where this technique can be applied, or in those of Gerstein and Jackiw, however with conflicting interpretations. Finally, we will show that in the context of the adopted technique the desired results emerge, in a natural way, within the context of an universal interpretation for the amplitudes where the ambiguities are automatically eliminated. (author)

Symmetry breaking and electrical conductivity of La0.7Sr0.3Cr0.4Mn0.6O3-δ perovskite as SOFC anode material

International Nuclear Information System (INIS)

Reyes-Rojas, A.; Alvarado-Flores, J.; Esparza-Ponce, H.; Esneider-Alcala, M.; Espitia-Cabrera, I.; Torres-Moye, E.

2011-01-01

Research highlights: → Perovskite-type La 0.7 Sr 0.3 Cr 0.4 Mn 0.6 O 3-δ -NiO nucleation kinetics. Symmetry-breaking by introducing Ni 2+ cations at 1050 deg. C. Phase transition from high temperature aristotype R3-bar c to hettotype I4/mmm. At low Ni concentration ρ resistivity decreases when increasing the temperature. For Ni concentration higher than 25% ρ resistivity increases. - Abstract: This work is focused on nanocrystalline solid oxide fuel cell synthesis and characterization (SOFC) anodes of La 0.7 Sr 0.3 Cr 0.4 Mn 0.6 O 3-δ (perovskite-type) with Nickel. Perovskite-type oxide chemical reactivity, nucleation kinetics and phase composition related with La 0.7 Sr 0.3 Cr 0.4 Mn 0.6 O 3-δ -NiO to La 0.7 Sr 0.3 Cr 0.4 Mn 0.6 O 3-δ -Ni transformation have been analyzed. SOFC anode powders were obtained by sol-gel synthesis, using polyvinyl alcohol as an organic precursor to get a porous cermet electrode after sintering at 1365 deg. C and oxide reduction by hydrogen at 800 deg. C/1050 deg. C for 8 h in a horizontal tubular reactor furnace under 10% H 2 /N 2 atmosphere. Composite powders were compressed into 10-mm diameter discs with 25-75 wt% Ni. Electrical and structural characterization by four-point probe method for conductivity, scanning electron microscopy (SEM), X-ray energy dispersive spectroscopy (EDS), X-ray diffraction (XRD), and Rietveld method were carried out. Symmetry-breaking by phase transition from high temperature aristotype R3-bar c to hettotype I4/mmm has been identified and confirmed by XRD and Rietveld method which can be produced by introducing Ni 2+ cations in the perovskite solid solution. Rietveld analysis suggests that Ni contents are directly proportional to La 0.7 Sr 0.3 Cr 0.4 Mn 0.6 NiO 3.95 tetragonal structure cell volume and inversely proportional to Ni cubic structure cell volume after reduction at 1050 deg. C. Kinetic analysis indicated that the Johnson-Mehl-Avrami equation is able to provide a good fit to phase

Mineralogical and chemical characterization of iron-, manganese-, and copper-containing synthetic hydroxyapatites

Science.gov (United States)

Sutter, B.; Ming, D. W.; Clearfield, A.; Hossner, L. R.

2003-01-01

The National Aeronautics and Space Administration's (NASA) Advanced Life Support (ALS) Program is evaluating the use of Fe-, Mn-, and Cu-containing synthetic hydroxyapatite (SHA) as a slow release fertilizer for crops that might be grown on the International Space Station or at Lunar and Martian outposts. Separate Fe-, Mn-, and Cu-containing SHA materials along with a transition-metal free SHA (pure-SHA) were synthesized using a precipitation method. Chemical and mineralogical analyses determined if and how Fe, Mn, and Cu were incorporated into the SHA structure. X-ray diffraction (XRD), Rietveld refinement, and transmission electron microscopy (TEM) confirmed that SHA materials with the apatite structure were produced. Chemical analyses indicated that the metal containing SHA materials were deficient in Ca relative to pure-SHA. The shift in the infrared PO4-mu 3 vibrations, smaller unit cell parameters, smaller particle size, and greater structural strain for Fe-, Mn-, and Cu-containing SHA compared with pure-SHA suggested that Fe, Mn, and Cu were incorporated into SHA structure. Rietveld analyses revealed that Fe, Mn, and Cu substituted into the Ca2 site of SHA. An Fe-rich phase was detected by TEM analyses and backscattered electron microscopy in the Fe-containing SHA material with the greatest Fe content. The substitution of metals into SHA suggests that metal-SHA materials are potential slow-release sources of micronutrients for plant uptake in addition to Ca and P.

Effect of molybdenum on structure, microstructure and mechanical properties of biomedical Ti-20Zr-Mo alloys.

Science.gov (United States)

Kuroda, Pedro Akira Bazaglia; Buzalaf, Marília Afonso Rabelo; Grandini, Carlos Roberto

2016-10-01

Titanium has an allotropic transformation around 883°C. Below this temperature, the crystalline structure is hexagonal close-packed (α phase), changing to body-centered cubic (β phase). Zirconium has the same allotropic transformation around 862°C. Molybdenum has body-centered cubic structure, being a strong β-stabilizer for the formation of titanium alloys. In this paper, the effect of substitutional molybdenum was analyzed on the structure, microstructure and selected mechanical properties of Ti-20Zr-Mo (wt%) alloys to be used in biomedical applications. The samples were prepared by arc-melting and characterized by x-ray diffraction with subsequent refinement by the Rietveld method, optical and scanning electron microscopy. The mechanical properties were analyzed by Vickers microhardness and dynamic elasticity modulus. X-ray measurements and Rietveld analysis revealed the presence of α' phase without molybdenum, α'+α″ phases with 2.5wt% of molybdenum, α″+β phases with 5 and 7.5wt% of molybdenum, and only β phase with 10wt% of molybdenum. These results were corroborated by microscopy results, with a microstructure composed of grains of β phase and lamellae and needles of α' and α″ phase in intra-grain the region. The hardness of the alloy was higher than the commercially pure titanium, due to the action of zirconium and molybdenum as hardening agents. The samples have a smaller elasticity modulus than the commercially pure titanium. Copyright © 2016 Elsevier B.V. All rights reserved.

Room temperature mechanosynthesis and microstructure characterization of nanocrystalline Si{sub 0.9}Al{sub 0.1}C

Energy Technology Data Exchange (ETDEWEB)

Bandyopadhyay, S. [Department of Physics, The University of Burdwan, Golapbag, Burdwan, 713104, West Bengal (India); Dutta, H. [Department of Physics, Vivekananda College, Burdwan, 713103, West Bengal (India); Kar, T. [Department of Materials Science, Indian Association for the Cultivation of Science, Jadavpur, Kolkata, 700032, West Bengal (India); Pradhan, S.K., E-mail: skp_bu@yahoo.com [Department of Physics, The University of Burdwan, Golapbag, Burdwan, 713104, West Bengal (India)

2016-02-01

This article reports the synthesis and microstructure characterization of nanocrystalline Si{sub 0.9}Al{sub 0.1}C powder obtained by mechanical milling the mixture of Si, Al and graphite powders at room temperature under inert atmosphere. XRD patterns of ball-milled powders clearly reveal the nucleation of Si{sub 0.9}Al{sub 0.1}C phase after 5 h of milling and the stoichiometric cubic Si{sub 0.9}Al{sub 0.1}C is formed after 10 h of milling with crystallite size of ∼3 nm. Microstructure of ball-milled powders in terms of different lattice imperfections is characterized by employing both Rietveld's method of structure refinement using XRD data and high resolution transmission electron microscope (HRTEM). HRTEM micrographs of 10 h milled powder substantiate the formation of nanocrystalline Si{sub 0.9}Al{sub 0.1}C compound without any contamination and confirm the findings of Rietveld analysis using XRD data. - Highlights: • Cubic Si{sub 0.9}Al{sub 0.1}C is formed after 5 h of milling of Si, Al and graphite powders. • Nanocrystalline Si{sub 0.9}Al{sub 0.1}C with particle size ∼3 nm is obtained after 10 h milling. • Average particle size of Si{sub 0.9}Al{sub 0.1}C from XRD analysis and HRTEM is very close.

Compressive strain-dependent bending strength property of Al2O3-ZrO2 (1.5 mol% Y2O3) composites performance by HIP

International Nuclear Information System (INIS)

Reyes-Rojas, A.; Esparza-Ponce, H.; De la Torre, S.D.; Torres-Moye, E.

2009-01-01

Nanometric powders and sintered ceramics of Al 2 O 3 -ZrO 2 (1.5 mol% Y 2 O 3 ) prepared by hot isostatic pressing HIP have been studied. A detailed crystallographic study has been performed through X-ray diffraction, Williamson-Hall method, Rietveld method and high-resolution electron microscopy HREM analysis. The crystallographic structure data, such as domain size, lattice parameters, wt% phase, and micro-strain direction have been obtained using Rietveld refinement and Williamson-Hall methods. The results revealed that the compressive strain (ε) increased from 0.56 to 1.18 (10 -3 ) as the t-ZrO 2 content increased too. The HREM interface study conducted along the [0 0 0 1]Al 2 O 3 ||[0 0 1]ZrO 2 zone axis revealed a micro-strain lattice distortion accumulated at the grain boundary due to the ZrO 2 martensitic phase transformation on cooling, t-ZrO 2 grains coalescence and to the grain growth of α-Al 2 O 3 which cause elongated tetragonal crystals. Micro-strain lattice distortion is adjusted by the shear displacements of the planes (1 1 0) and (11-bar0) along [1-bar10] and [1-bar1-bar0] crystallographic directions, respectively; these planes are arrested by the (101-bar0) alumina plane. In this case, semi-coherent interfaces were observed along the grain boundary. It is verified that the bending strength increased in connection with the strain accumulation and amount of tetragonal structure

Synthesis, structural characteristics and dielectric properties of a new K{sub 2}NiF{sub 4}-type phase Sr{sub 2}Mn{sub 0.5}Ti{sub 0.5}O{sub 4}

Energy Technology Data Exchange (ETDEWEB)

Chupakhina, T.I., E-mail: chupakhina@ihim.uran.ru [Institute of Solid State Chemistry of the Ural Branch of the Russian Academy of Sciences, 91, Pervomaiskaya Str., Ekaterinburg (Russian Federation); Melnikova, N.V. [Ural Federal University, 19, Mira Str., Ekaterinburg (Russian Federation); Gyrdasova, O.I. [Institute of Solid State Chemistry of the Ural Branch of the Russian Academy of Sciences, 91, Pervomaiskaya Str., Ekaterinburg (Russian Federation)

2016-06-15

A new K{sub 2}NiF{sub 4}-type phase Sr{sub 2}Mn{sub 0,5}Ti{sub 0,5}O{sub 4} have been synthesized by a sol–gel procedure and characterized by X-ray powder diffraction, thermogravimetric analysis and scanning electron microscopy. There are no oxide ion vacancies in these materials; oxidation states of manganese and titanium were estimated as +4. Rietveld profile analysis shows that the phase crystallizes with tetragonal unit cell in the space group I4/mmm. Substitution of Ti{sup 4+} for Mn{sup 4+} does not affect the distortion of coordination polyhedra (Mn,Ti)O{sub 6} and SrO{sub 9}. The dielectric properties of the ceramic samples are caused by structural and charge characteristics, regular coordination polyhedra SrO{sub 9} and lack of charge ordering, which can lead to significant permittivity. Increase of the dielectric constant at temperatures above 453 K is caused mainly by the grain boundary processes explained in terms of the Maxwell–Wagner polarization model. - Highlights: • The new complex oxide Sr{sub 2}Mn{sub 0,5}Ti{sub 0,5}O{sub 4} was prepared. • The structures of the compound were analyzed by Rietveld refinement. • Distortions of SrO{sub 9} and (Mn,Ti)O{sub 6} polyhedra are not strong. • Dielectric properties are determined by regular structure and lack of charge ordering. • Permittivity increase under heat is associated with processes at the grain boundaries.

Tunable-color luminescence via energy transfer in NaCa13/18Mg5/18PO4:A (A = Eu2+/Tb3+/Mn2+, Dy3+) phosphors for solid state lighting.

Science.gov (United States)

Li, Kai; Fan, Jian; Mi, Xiaoyun; Zhang, Yang; Lian, Hongzhou; Shang, Mengmeng; Lin, Jun

2014-11-17

A series of NaCa13/18Mg5/18PO4(NCMPO):A (A = Eu(2+)/Tb(3+)/Mn(2+), Dy(3+)) phosphors have been prepared by the high-temperature solid-state reaction method. The X-ray diffraction (XRD) and Rietveld refinement, X-ray photoelectron spectroscopy (XPS), photoluminescence (PL), cathodoluminescence (CL), decay lifetimes, and PL quantum yields (QYs) were utilized to characterize the phosphors. The pure crystalline phase of as-prepared samples has been demonstrated via XRD measurement and Rietveld refinements. XPS reveals that the Eu(2+)/Tb(3+)/Mn(2+) can be efficiently doped into the crystal lattice. NCMPO:Eu(2+)/Tb(3+)/Mn(2+) phosphors can be effectively excited under UV radiation, which show tunable color from purple-blue to red including white emission based on energy transfer from Eu(2+) to Tb(3+)/Mn(2+) ions. Under low-voltage electron beam bombardment, the NCMPO:A (A = Eu(2+)/Tb(3+)/Mn(2+), Dy(3+)) display their, respectively, characteristic emissions with different colors, and the CL spectrum of NCMPO:0.04Tb(3+) has the comparable intensity to the ZnO:Zn commercial product. In addition, the calculated CIE coordinate of NCMPO:0.04Tb(3+) (0.252, 0.432) is more saturated than it (0.195, 0.417). These results reveal that NCMPO:A (A = Eu(2+)/Tb(3+)/Mn(2+), Dy(3+)) may be potential candidate phosphors for WLEDs and FEDs.

Evaluation of the phase composition of (NH4)2SO4 + (NH4)H2PO4 mixtures by X-ray diffractometry

International Nuclear Information System (INIS)

Ortiz, Angel L.; Cumbrera, Francisco L.; Perez, Jose; Vas, Beatriz del; Perez, Eduardo

2009-01-01

The phase composition of standard (NH 4 ) 2 SO 4 + (NH 4 )H 2 PO 4 mixtures was investigated by X-ray diffractometry (XRD) using the internal-standard, reference-intensity-ratio, and Rietveld methods. It was found that the Rietveld method yields the most accurate phase-composition measurements, with an average error of ∼2 wt.%. It was also found that the internal-standard method is only effective in determining the phase composition if the calibration curve for (NH 4 )H 2 PO 4 is used, giving an average error of ∼6.5 wt.%. On the contrary, the internal-standard method with the calibration curve of the (NH 4 ) 2 SO 4 phase and the reference-intensity-ratio method are not valid. The inappropriateness of these two methods was attributed to graininess in the (NH 4 ) 2 SO 4 phase, with the attendant deviation of its diffracted intensities from the theoretical values. Direct scanning electron microscopy observations of the morphology of the powder particles in the mixtures showed clear evidence of the large agglomerates formed because the individual powder particles are partially sintered together during milling, thus corroborating the graininess determined by the XRD analyses. Finally, the implications of the present study for the quantitative phase-composition analysis of (NH 4 ) 2 SO 4 + (NH 4 )H 2 PO 4 mixtures, which are of great technological importance for the fire prevention industry, are discussed.

CZTS nanoparticle absorber layer for thin film solar cells

DEFF Research Database (Denmark)

Symonowicz, Joanna; Jensen, Kirsten M. Ørnsbjerg; Engberg, Sara Lena Josefin

a pure CZTS kesterite phase without secondary phases as they result in structural inhomogeneity, local fluctuation of open circuit voltage and high carrier recombination [3]. This leads to poor device performance and repeatability issues. Here, we present how the synthesis parameters affect the resulting...... CZTS nanoparticles. The product is characterized by XRD, EDS, and Raman spectroscopy in order to fully detect possible secondary phases and characterize the CZTS phase. By combining Rietveld refinement of the XRD data with X-ray total scattering with PDF analysis, the nanoscale atomic structure...

Neutron diffraction studies on Ca1-xBaxZr4P6O24 solid solutions

International Nuclear Information System (INIS)

Achary, S.N.; Jayakumar, O.D.; Patwe, S.J.; Kulshreshtha, S.K.; Tyagi, A.K.; Shinde, A.B.; Krishna, P.S.R.

2008-01-01

Herein we report the results of detailed crystallographic studies of Ca 1-x Ba x Zr 4 P 6 O 24 compositions from combined Rietveld refinements of powder X-ray and neutron diffraction data. All the studied compositions crystallize in rhombohedral lattice (space group R-3 No. 148). A continuous solid solution is concluded from the systematic variation of unit cell parameters. The variation of unit cell parameters with the composition indicates decreasing trend in α parameter with increasing Ba 2+ concentration contrast to an increasing trend in c parameter. (author)

Characteristic length scale dependence on conductivity for La2-xErxMo2O9 (0.05 ≤ x ≤ 0.3) oxide ion conductors

Science.gov (United States)

Paul, T.; Ghosh, A.

2016-05-01

Structural property of polycrystalline La2-xErxMo2O9 has been investigated. Rietveld refinements at room temperature of the materials suggest a single phase nature with cubic symmetry (space group P213). The electron density contour plot confirms the nature of different cation-oxygen bonds. Time dependent mean square displacement (√) and the spatial extent of the sub-diffusive motion (√) are evaluated using the linear response theory. The localized hop at O2 and O3 sites is found to be favorable for oxygen ion migration for these systems.

Characterization of superconducting coil for fault current limitation

International Nuclear Information System (INIS)

Polasek, Alexander; Dias, Rodrigo; Niedu, Daniel Brito; Ogasawara, Tsuneharu; Oliveira Filho, Orsino Borges de; Serra, Eduardo Torres; Gomes Junior, George; Amorim, Helio Salim

2010-01-01

The increasing power demand has been raising fault currents up to dangerous levels. Superconducting fault current limiters are a promising solution for this problem. In the present work, we studied a superconducting Bi-2212 coil that is used for fault current limitation. Samples were analyzed by XRD, SEM/EDS and measurement of critical temperature (Tc). The Rietveld method was employed for phase quantification. Relatively high Bi-2212 fractions were found. However, Tc varies from a sample to another one. Variations of local Tc are attributed to variations of oxygen content in Bi- 2212 phase. (author)

Synthesis and characterization of K{sub 2}Ln{sub 2/3}Ta{sub 2}O{sub 7}·nH{sub 2}O (Ln= La, Pr, Nd), layered tantalates photo catalysts for water splitting

Energy Technology Data Exchange (ETDEWEB)

Valencia S, H.; Tavizon, G. [UNAM, Instituto de Quimica, Ciudad Universitaria, 04510 Ciudad de Mexico (Mexico); Pfeiffer, H. [UNAM, Instituto de Investigaciones en Materiales, Ciudad Universitaria, 04510 Ciudad de Mexico (Mexico); Acosta, D. [UNAM, Instituto de Fisica, Ciudad Universitaria, 04510 Ciudad de Mexico (Mexico); Negron M, A., E-mail: hvalencia@utp.edu.co [UNAM, Instituto de Ciencias Nucleares, Ciudad Universitaria, 04510 Ciudad de Mexico (Mexico)

2015-07-01

Three compounds of the K{sub 2}Ln{sub 2/3}Ta{sub 2}O{sub 7} (Ln = La, Nd, Pr) cation-deficient Ruddlesden-Popper series were prepared by the Pechini (polymeric complex) method. The crystal structures of the hydrated form of these compounds were determined by Rietveld analysis of the X-ray power diffraction data and High Resolution Transmission Electron Microscopy (HRTEM). The samples were also analyzed to determine specific area (Bet), degree of hydration (Thermogravimetric analysis), and photo catalytic activity for hydrogen evolution from water and aqueous methanol solution. (Author)

Barium strontium titanate powders prepared by spray pyrolysis

International Nuclear Information System (INIS)

Brankovic, G.; Brankovic, Z.; Goes, M.S.; Paiva-Santos, C.O.; Cilense, M.; Varela, J.A.; Longo, E.

2005-01-01

Ultasonic spray pyrolysis (SP) has been investigated for the production of the barium strontium titanate (BST) powders from the polymeric precursors. The processing parameters, such as flux of aerosol and temperature profile inside the furnace, were optimized to obtain single phase BST. The powders were characterized by the methods of X-ray diffraction analysis, SEM, EDS and TEM. The obtained powders were submicronic, consisting of spherical, polycrystalline particles, with internal nanocrystalline structure. Crystallite size of 10 nm, calculated using Rietveld refinement, is in a good agreement with results of HRTEM

Position-sensitive detector system OBI for High Resolution X-Ray Powder Diffraction using on-site readable image plates

International Nuclear Information System (INIS)

Knapp, M.; Joco, V.; Baehtz, C.; Brecht, H.H.; Berghaeuser, A.; Ehrenberg, H.; Seggern, H. von; Fuess, H.

2004-01-01

A one-dimensional detector system has been developed using image plates. The detector is working in transmission mode or Debye-Scherrer geometry and is on-site readable which reduces the effort for calibration. It covers a wide angular range up to 110 deg. and shows narrow reflection half-widths depending on the capillary diameter. The acquisition time is in the range of minutes and the data quality allows for reliable Rietveld refinement of complicated structures, even in multi-phase samples. The detector opens a wide field of new applications in kinetics and temperature resolved measurements

Crystal structure refinement and microwave dielectric properties of new low dielectric loss AZrNb2O8 (A: Mn, Zn, Mg and Co) ceramics

International Nuclear Information System (INIS)

Ramarao, S.D.; Murthy, V.R.K.

2013-01-01

Graphical abstract: -- The effects of substituting different cations (Mn, Zn, Mg and Co) at the A-site of AZrNb 2 O 8 compounds on structural parameters such as packing fraction and B-site octahedral distortion were studied using X-ray powder diffraction in conjunction with Rietveld refinement. Variations in the dielectric constant (ε r ) were explained by the ionic polarizability of the compositions. The quality factor (Q × f) and temperature coefficient of resonant frequency (τ f ) were correlated with the packing fraction and B-site octahedral distortions (δ) in these compositions, respectively

Determination of the electronic, dielectric, and optical properties of sillenite Bi12TiO20 and perovskite-like Bi4Ti3O12 materials from hybrid first-principle calculations

KAUST Repository

Lardhi, Sheikha F.; Noureldine, Dalal; Harb, Moussab; Ziani, Ahmed; Cavallo, Luigi; Takanabe, Kazuhiro

2016-01-01

Density functional theory calculation was conducted to determine the optoelectronic properties of bismuthtitanate sillenite (Bi12TiO20) and perovskite-like (Bi4Ti3O12) structures. The lattice parameters were experimentally obtained from Rietveld analysis. The density functional perturbation theory approach was used with the standard Perdew–Burke–Ernzerhof functional and screened Coulomb hybrid Heyd–Scuseria–Ernzerhof functional to investigate the electronic structure and absorption coefficient. Both compounds have good carrier transport properties, low effective hole and electron masses, high dielectric constant, and low exciton binding energy.

Synthesis and structural investigation of new Co1-xNixTeO4 (x = 0, 0.2, 0.5, 0.8 and 1) compounds

Science.gov (United States)

Patel, Akhilesh K.; Singh, Harishchandra; Suresh, K. G.

2018-05-01

The new polycrystalline compounds Co1-xNixTeO4 (x = 0, 0.2, 0.5, 0.8 and 1) were prepared by sol-gel method and their structural properties have been studied. Structural investigation through Rietveld method shows monoclinic structure with space group P21/c for all compounds. All compounds polyhedral structure found to be in octahedral form with cations (M) at the center and six oxygen atoms at corner of octahedral structure. The lattice parameters variation with Ni substitution are found to be decreasing with Ni substitution.

Structural, dielectric and magnetic studies of Ba and Nb codoped BiFeO{sub 3} multiferroics

Energy Technology Data Exchange (ETDEWEB)

Jangra, Sandhaya, E-mail: sndh17@gmail.com; Sanghi, Sujata; Agarwal, Ashish; Kaswan, Kavita; Rangi, Manisha; Singh, Ompal [Department of Applied Physics, Guru Jambheshwar University of Science and Technology, Hisar, Haryana-125001 (India)

2016-05-23

Polycrystalline materials with composition Bi{sub 0.8}Ba{sub 0.2}Fe{sub 1-x}Nb{sub x}O{sub 3} (x= 0.07, 0.10) were prepared via solid state reaction method. Preliminary analysis of structure was performed by XRD technique and confirmed formation of single phase crystalline materials. Rietveld refinement reveled that these materials have rhombohedral phase with R3c space group. Dielectric constant increased with temperature and Nb concentration. Ba and Nb co-doping suppress the spiral spin structure and produce net magnetization.

Validation of the method of quantitative phase analysis by X-ray diffraction in API: case of Tibolone

International Nuclear Information System (INIS)

Silva, R P; Ambrósio, M F S; Epprecht, E K; Avillez, R R; Achete, C A; Kuznetsov, A; Visentin, L C

2016-01-01

In this study, different structural and microstructural models applied to X-ray analysis of powder diffraction data of polymorphic mixtures of known concentrations of Tibolone were investigated. The X-ray data obtained in different diffraction instruments were analysed via Rietveld method using the same analytical models. The results of quantitative phase analysis show that regardless of the instrument used, the values of the calculated concentrations follow the same systematics with respect to the final errors. The strategy to select a specific analytical model that leads to lower measurement errors is here presented. (paper)

Determination of the electronic, dielectric, and optical properties of sillenite Bi12TiO20 and perovskite-like Bi4Ti3O12 materials from hybrid first-principle calculations

KAUST Repository

Lardhi, Sheikha F.

2016-04-05

Density functional theory calculation was conducted to determine the optoelectronic properties of bismuthtitanate sillenite (Bi12TiO20) and perovskite-like (Bi4Ti3O12) structures. The lattice parameters were experimentally obtained from Rietveld analysis. The density functional perturbation theory approach was used with the standard Perdew–Burke–Ernzerhof functional and screened Coulomb hybrid Heyd–Scuseria–Ernzerhof functional to investigate the electronic structure and absorption coefficient. Both compounds have good carrier transport properties, low effective hole and electron masses, high dielectric constant, and low exciton binding energy.

Characterization of Structural Disorder in γ-Ga2O3

OpenAIRE

Playford, Helen. Y.; Hannon, Alex C.; Tucker, Matthew G.; Dawson, Daniel M.; Ashbrook, Sharon E.; Kastiban, Reza J.; Sloan, Jeremy; Walton, Richard I.

2014-01-01

The authors thank the STFC for provision of beam time at ISIS and for part-funding a studentship for H.Y.P. through its Centre for Materials Physics and Chemistry (Grant CMPC08104). H.Y.P. also thanks the EPSRC for providing a Postdoctoral Prize Award (Grant EP/P50578X/1). Solvothermal oxidation of metallic gallium in monoethanolamine for 72 h at 240 degrees C yields a crystalline sample of gamma-Ga2O3 (similar to 30 nm crystallites). While Rietveld refinement (cubic spinel structure, Fd (...

Comparação estrutural entre amostras de materiais tipo hidrotalcita obtidas a partir de diferentes rotas de síntese

Directory of Open Access Journals (Sweden)

Luciano H. Chagas

2012-01-01

Full Text Available Three samples of hydrotalcite-like materials (HTC were synthesized and their structural characteristics were compared with two HTCs obtained commercially. Thermal analyses, FT-IR, PXRD and textural analyses were used to investigate the structural differences between commercial and synthetic samples. Particularly, the memory effect was observed at temperature higher than 600 ºC. The Rietveld refinements were obtained with expressive accuracy and the statistical parameters of goodness of fit are quite satisfactory. In conclusion, the procedures adopted in synthesis of HTC produced crystalline materials with high surface area materials.

Magnetic structure evolution in mechanically milled nanostructured ZnFe2O4 particles

DEFF Research Database (Denmark)

Jiang, Jianzhong; Wynn, P.; Mørup, Steen

1999-01-01

Nanostructured partially-inverted ZnFe2O4 particles have been prepared from bulk ZnFe2O4 by high-energy ball milling in an open container. The grain size reduction, cation site distributions, and the evolution of magnetic structures have been studied by x-ray diffraction with Rietveld structure...... refinements, transmission electron microscopy, and Mossbauer spectroscopy. It is found that a change of magnetic structure from an antiferromagnetic to a ferrimagnetic (or ferromagnetic) structure occurs in the milled samples. This change is correlated with the redistribution of the cations, Zn and Fe...

スクッテルド鉱型化合物LnRu4P12(Ln=ランタニド)の構造と電子物性

OpenAIRE

内海, 貴徳; 関根, ちひろ; 木村, 繁之; 井上, 雅士; 城谷, 一民

1999-01-01

Ternary ruthenium phosphides LnRu4P12 (Ln=La,Ce,Pr,Nd,Sm,Eu,Gd and Tb) with the filled skutterudite-type structure have been prepared at high temperatures and high pressures. The crystal structure of a new compound TbRu4P12 is refined by the Rietveld analysis of the powder X-ray diffraction data. The physical properties of LnRu4P12 have been studied by means of electrical resistivity, magnetic susceptibility, magnetization and specific-heat measurements at low temperatures. LaRu4P12 is a supe...

Structural study of the semimagnetic semiconductor Zn{sub 0.5}Mn{sub 0.5}In{sub 2}Te{sub 4}

Energy Technology Data Exchange (ETDEWEB)

Delgado, G.E. [Laboratorio de Cristalografia, Departamento de Quimica, Facultad de Ciencias, Universidad de Los Andes, Merida (Venezuela); Sagredo, V. [Laboratorio de Magnetismo en Solidos, Departamento de Quimica, Facultad de Ciencias, Universidad de Los Andes, Merida (Venezuela)

2009-02-15

The semimagnetic semiconductor alloy Zn{sub 0.5}Mn{sub 0.5}In{sub 2}Te{sub 4} was refined from an X-ray powder diffraction pattern using the Rietveld method. This compound crystallizes in the space group I anti 42m (N {sup circle} 121), Z=2, with unit cell parameters a=6.1738(1)A, c=12.3572(4)A, V=471.00(2)A3, c/a=2.00. This material crystallizes in a stannite-type structure. (copyright 2009 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

High-temperature elastic properties of in situ-reinforced Si3N4

International Nuclear Information System (INIS)

Swift, Geoffrey A.; Uestuendag, Ersan; Clausen, Bjoern; Bourke, Mark A.M.; Lin, H.-T.

2003-01-01

A high-temperature tensile stress study of a monolithic silicon nitride (Si 3 N 4 ) was performed with time-of-flight neutron diffraction. A dedicated engineering diffractometer was employed at temperatures reaching 1375 deg. C. Rietveld refinements of diffraction spectra allowed the determination of (1) the coefficient of thermal expansion tensor during heating and (2) lattice strains during loading. The stress-strain response of individual lattice reflections was used to calculate the single-crystal elastic stiffness tensor of Si 3 N 4 at 1375 deg. C via a self-consistent model

Synthesis and characterization of K2Ln2/3Ta2O7·nH2O (Ln= La, Pr, Nd), layered tantalates photo catalysts for water splitting

International Nuclear Information System (INIS)

Valencia S, H.; Tavizon, G.; Pfeiffer, H.; Acosta, D.; Negron M, A.

2015-01-01

Three compounds of the K 2 Ln 2/3 Ta 2 O 7 (Ln = La, Nd, Pr) cation-deficient Ruddlesden-Popper series were prepared by the Pechini (polymeric complex) method. The crystal structures of the hydrated form of these compounds were determined by Rietveld analysis of the X-ray power diffraction data and High Resolution Transmission Electron Microscopy (HRTEM). The samples were also analyzed to determine specific area (Bet), degree of hydration (Thermogravimetric analysis), and photo catalytic activity for hydrogen evolution from water and aqueous methanol solution. (Author)

Comment on 'Pressure-induced changes in transport properties of layered La1.2Ca1.8Mn2O7'

International Nuclear Information System (INIS)

Ganguly, R.; Siruguri, V.; Gopalakrishnan, I.K.; Yakhmi, J.V.

2000-01-01

We show that the compound La 1.2 Ca 1.8 Mn 2 O 7 does not form with layered Sr 3 Ti 2 O 7 -type structure as reported by Kamenev et al. [Phys. Rev. B 56, R12 688 (1997)]. Detailed analysis of the powder x-ray diffraction pattern of this compound (synthesized by using the solid-state method) by Rietveld method shows that it forms a multiphase mixture comprising hole-doped perovskite manganates (La 1-x Ca x MnO 3 ) as the majority phases and CaO as the minority phase

In Situ Observation of Antisite Defect Formation during Crystal Growth

International Nuclear Information System (INIS)

Kramer, M. J.; Napolitano, R. E.; Mendelev, M. I.

2010-01-01

In situ x-ray diffraction (XRD) coupled with molecular dynamics (MD) simulations have been used to quantify antisite defect trapping during crystallization. Rietveld refinement of the XRD data revealed a marked lattice distortion which involves an a axis expansion and a c axis contraction of the stable C11b phase. The observed lattice response is proportional in magnitude to the growth rate, suggesting that the behavior is associated with the kinetic trapping of lattice defects. MD simulations demonstrate that this lattice response is due to incorporation of 1% to 2% antisite defects during growth.

Crystal structures and electronic properties of UTixNb3-xO10 (x=0,1/3,1) and of the intercalation compound Li0.9UTiNb2O10

International Nuclear Information System (INIS)

Dickens, P.G.; Flynn, G.J.; Patat, S.; Stuttart, G.P.

1997-01-01

Complete crystal structures of the related phases UTi x Nb 3-x O 10 (x=0,1/3,1) and of the intercalation compound Li 0.9 UTiNb 2 O 10 have been determined by Rietveld analysis of room-temperature powder neutron diffraction data. The new structural data combined with magnetic susceptibility measurements made in the range 5 y 1 U V 1+y-x U VI x-y Ti IV x Nb V 3-x O 10 (y≤ x ≤1) with U V (f 1 ) being the only paramagnetic species present. (Author)

Estudo de caso aplicando modelo para identificação de potenciais geradores de intangíveis

Directory of Open Access Journals (Sweden)

Rodney Wernke

2003-12-01

Full Text Available Relata estudo de caso em que foi aplicado o modelo Mapa para Identificação de Potenciais Geradores de Intangíveis. Após mencionar resumidamente a ferramenta utilizada, apresentam-se os procedimentos seguidos para implementar tal modelo numa empresa industrial, evidenciando os passos seguidos, as análises realizadas, os resultados alcançados e as limitações inerentes.This article reports on a case study which applied the model called Map for the Identification of Potential Intangible Asset Generators. After a summarized description of the applied tool, we present the procedures followed to implement such a model in an industrial company, disclosing the steps that were taken, the analyses carried out, obtained results and inherent limitations.

Conformación de equipos de proyectos de software aplicando algoritmos metaheurísticos de trayectoria multiobjetivo

Directory of Open Access Journals (Sweden)

Ana Lilian Infante

2014-12-01

Full Text Available La inadecuada conformación de equipos de proyecto de software es un problema que afecta a la industria de software a nivel mundial. Este proceso resulta complejo, teniendo en cuenta que debe considerar varios factores, como son, asignar a los roles del equipo las personas con las competencias apropiadas, considerar las incompatibilidades entre los miembros y la carga de trabajo, entre otros. Esta situación se torna más compleja en organizaciones medianas y grandes, debido a la gran cantidad de combinaciones de asignaciones posibles, por lo que esta etapa es prácticamente imposible de abordar de manera eficiente, sin la ayuda de modelos matemáticos que representen el problema a resolver lo más objetivamente posible. Este trabajo toma como antecedente un modelo que incluye tanto factores individuales como factores de equipo y plantea: maximizar las competencias de los trabajadores, minimizar las incompatibilidades entre los miembros del equipo y balancear la carga de trabajo. Incluye además, en una versión ampliada del modelo, minimizar el costo de desarrollar software a distancia. El modelo citado responde a un problema de optimización combinatorio multiobjetivo, por lo que para su solución se utilizaron algunas variantes multiobjetivo de los algoritmos metaheurísticos: Búsqueda Tabú, Recocido Simulado y Escalador de Colinas. El estudio experimental realizado ha llevado a identificar que las variantes multiobjetivo del Escalador de Colinas: Escalador de Colinas Estocático Multiobjetivo, Escalador de Colinas Multiobjetivo por mayor distancia y Escalador de Colinas Multiobjetivo con Reinicio, así como el algoritmo Recocido Simulado Multiobjetivo Multicaso son los que mejores resultados obtienen en este problema.

Eficiencia técnica y ambiental de la camaronicultura en Nayarit aplicando el índice de Malmquist

Directory of Open Access Journals (Sweden)

Francisco Javier Martínez-Cordero

2015-01-01

Full Text Available A partir de una base de datos no homogénea de 32 granjas de camarón en Nayarit para el periodo 2008-2011, el presente estudio aplica el índice de Malmquist para analizar su eficiencia técnica ET y ambientalmente ajustada EAA de una empresa o industria acuícola sostenible. Los resultados indican que los niveles de ET y EAA se han mantenido arriba de 0.80 y 0.75 en promedio, respectivamente. En general, los resultados confirman estudios regionales previos del cultivo de camarón, en función de que los rendimientos (kg/ha/año pueden ser decrecientes por causa de las enfermedades virales. Se recomienda aplicar estos indicadores de manera continua para asistir la planificación y toma de decisión tanto a nivel empresa como industria.

Strain and stress tensors of rolled uranium plate by Rietveld refinement of TOF neutron-diffraction data

International Nuclear Information System (INIS)

Balzar, D.; Popa, N.C.; Vogel, S.

2010-01-01

We report the complete macroscopic average strain and stress tensors for a cold-rolled uranium plate, based on the neutron TOF measurements. Both tensors were determined by the least-squares refinement of the interplanar spacings of 19 Bragg reflections. Based on the pole figures, as determined by GSAS, a triclinic sample symmetry of the uranium plate was assumed. Strain and stress are tensile in both the transverse and rolling directions and very small in the normal direction (through the thickness of the plate). Shear strain and stress components are compressive and of significant magnitude.

PERCEPCIÓN INDUSTRIA-AMBIENTE DE ESTUDIANTES UNIVERSITARIOS DE INGENIERÍA INDUSTRIAL

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Quetzalli Aguilar-Virgen

2015-01-01

Full Text Available El objetivo del presente estudio fue analizar la percepción de estudiantes universitarios sobre su papel en la minimización de impactos ambientales, aplicando la filosofía de CPS (consumo y producción sustentable. Se diseñó y validó un cuestionario; el cual se aplicó a 288 estudiantes con un nivel de confianza 95% y un error del 10%. Los estudiantes están conscientes de que es necesario optimizar sus procesos y hacer rentables sus empresas. Sin embargo, les falta mayor conocimiento en las herramientas de CPS para hacer los procesos más eficaces, eficientes y ambientalmente amigables. Es necesario que se cambien los paradigmas industria-ambiente para lograr sistemas productivos más sostenibles.

Estudos conformocionais de diversas proteínas em solução utilizando a técnica de espalhamento de raios-X à baixo ângulo-saxs

OpenAIRE

Viçoti, Magno Massolino [UNESP

2011-01-01

A técnica de espalhamento de raios-X a baixo ângulo – SAXS é uma poderosa ferramenta para a caracterização de macromoléculas biológicas em solução. Aplicando-a de forma correta podemos obter parâmetros físicos à respeito do material de estudo, como raio de giração, máxima dimensão, volume e superfície. Neste trabalho caracterizou-se em solução aquosa a macromolécula heterodimérica crotoxina com a variação do pH em ácido, básico e neutro. Esta proteína foi isolada da serpente sul-americana Cro...

Impacto de la conquista inca en la metalurgia de Los Amarillos (Quebrada de Humahuaca, Jujuy

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Carlos I. Angiorama

2011-01-01

Full Text Available En este trabajo analizamos el impacto de la conquista inca en la producción y circulación de objetos metálicos en el asentamiento conocido como Los Amarillos, uno de los más complejos de los localizados en la Quebrada de Humahuaca (Jujuy. Luego comparamos los resultados de nuestras investigaciones con los obtenidos por arqueometalurgos en otros lugares del país, demostrando que las repercusiones de la conquista incaica no han sido las mismas en todos los centros metalúrgicos de la región. Por el contrario, el Imperio reorganizó la producción y la circulación de objetos metálicos aplicando estrategias diferentes en los diversos casos estudiados.

Determinantes de las relaciones reales de intercambio de España con Alemania (1970-2010. Un análisis econométrico de la ventaja absoluta de costo intrasectorial

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Fahd Boundi Chraki

2017-07-01

Full Text Available El presente trabajo tiene como objeto analizar los determinantes de las relaciones reales de intercambio de España con Alemania, tomando como período 1970-2010. Para tal propósito, se lleva a cabo un análisis de series temporales aplicando pruebas de raíces unitarias y un test de cointegración, siendo el marco teórico de referencia el enfoque de Anwar Shaikh de la ventaja absoluta de costo intrasectorial. Finalmente, el análisis econométrico constata que el tipo de cambio real efectivo entre España y Alemania se encuentra sujeto en el largo plazo a los costos laborales unitarios reales relativos de la industria manufacturera de ambos países.

The Virtue of Knowing-How = A virtude do saber-como

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Santos, Felipe Rocha Lima

2015-01-01

Full Text Available Intelectualistas sobre o conhecimento-como afirmam que o conhecimento-como é um tipo de conhecimento proposicional. Antiintelectualistas procuram demonstrar que existem casos em que o agente possui conhecimento-como, mas não possuem conhecimento proposicional. Este artigo se concentra nos recentes argumentos antiintelectualistas propostos por Carter e Pritchard. Procuro mostrar que os argumentos de Carter e Pritchard não são bem sucedidos e que, aplicando a epistemologia das virtudes ao debate, pode-se concluir que o conhecimento-como compartilha as mesmas propriedades epistêmicas que o conhecimento proposicional. Se isso é o caso, então é possível afirmar que o conhecimento-como é um tipo de conhecimento proposicional, deixando a salvo novamente o intelectualismo

Calidad de servicio de la gestión de procura de Petróleos de Venezuela, S. A.

Directory of Open Access Journals (Sweden)

María Cristina Useche Aguirre

2013-04-01

Full Text Available El propósito de este trabajo es la calidad del servicio en la gestión de procura de PDVSA. Elestudio se aborda desde la teoría de la gerencia de valor al cliente (Albretch, 1998, empleandoun tipo descriptivo, con diseño de investigación no experimental transaccional. La poblaciónse encuentra conformada por todas (doce las empresas mixtas que requieren los servicios deprocura de PDVSA en la región zuliana. El análisis de la información se realizó aplicando los 92 procedimientos de la estadística descriptiva. Se concluye que el nivel de calidad del servicio es bajo, debido a las significativas discrepancias entre las expectativas y percepciones del servicio.