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Sample records for rmn calculos teoricos

  1. De la minus-valia a la diversidad funcional: un nuevo marco teorico-metodologico

    National Research Council Canada - National Science Library

    Ferreira, Miguel A.V

    2010-01-01

    En el presente texto, a partir de las propuestas del modelo social de la discapacidad, se propone un marco teorico que pretende abrir una via de investigacion que vaya mas alla de sus propuestas iniciales...

  2. Review of the Magnetocaloric Effect in RMnO3 and RMn2O5 Multiferroic Crystals

    Directory of Open Access Journals (Sweden)

    Mohamed Balli

    2017-02-01

    Full Text Available It is known that some of RMnO3 and RMn2O5 (R = rare earth multiferroic crystals reveal a strong interplay between their magnetic and electric order parameters, paving the way for applications in spintronic technologies. Additionally, recent works have also pointed out their potential utilization as refrigerants in magnetocaloric cooling systems for cryogenic tasks. In this paper, recent advances regarding the magnetocaloric properties of both RMnO3 and RMn2O5 families of multiferroics are reviewed. With the aim of understanding the RMnO3 and RMn2O5 magnetocaloric features, their structural and magnetic properties are discussed. The physics behind the magnetocaloric effect as well as some of its key thermodynamic aspects are also considered.

  3. I conflitti multiculturali e il diritto: un paradigma teorico

    Directory of Open Access Journals (Sweden)

    Carlotta Caldiroli

    2015-11-01

    Full Text Available Tra quelli che la letteratura in argomento chiama “conflitti multiculturali” ve ne sono alcuni il cui studio non può prescindere da una dimensione giuridica: si tratta dei cosiddetti “reati culturalmente motivati” e dei “diritti culturali”. Nel presente articolo non si prenderanno in considerazione le molteplici questioni sollevate dai due concetti nella filosofia politica e nella riflessione giuridica; l’analisi condotta riguarderà, piuttosto, una loro definizione minima. Appurato quali fenomeni si è soliti indicare come conflitti multiculturali con imprescindibili ripercussioni legali, ci si chiederà, infatti, cosa essi siano. Per rispondere, si proporrà un paradigma teorico all’interno del quale possano essere sussunte le diverse occorrenze tanto dei “reati culturalmente motivati” quanto dei “diritti culturali”; il paradigma è valido nell’alveo della tradizione liberale, alla quale mostrano di aderire gli stati interessati dai conflitti. Questi ultimi si configurano come situazioni in cui i soggetti coinvolti ritengono di non poter operare la distinzione, apparentemente non problematica, tra il conformare il proprio comportamento a quanto prescrivono le norme giuridiche e l’aderire alle valutazioni che in esse trovano riscontro e/o il derogare alle valutazioni della propria cultura di origine. Nel paragrafo conclusivo, infine, si accennerà al tema della risoluzione dei conflitti multiculturali; senza entrare nel merito dei diversi espedienti tecnici utilizzati per risolvere i singoli casi, si segnaleranno, sempre muovendo dal paradigma delineato, almeno due argomentazioni in base alle quali uno stato liberale può legittimamente respingere l’argomento culturale in sede giuridica.

  4. Sentidos y significados del trabajo: un analisis con base en diferentes perspectivas teorico-epistemologicas en Psicologia

    National Research Council Canada - National Science Library

    Chalfin Coutinho, Maria; Baasch, Davi; da Rosa Tolfo, Suzana; Soares Cugnier, Joana

    2011-01-01

    .... Este articulo presenta y analiza los principales abordajes teoricos identificados en las literaturas internacional y brasilena en el campo de la Psicologia, que tratan de los significados y de los sentidos...

  5. Caracterizacion del avance teorico, investigativo y/o de intervencion en resiliencia desde el ambito de las universidades en Colombia

    National Research Council Canada - National Science Library

    Rodriguez Arenas, Maria Stella; Munoz Ortega, Liliana; Trujillo Garcia, Sergio; Ospina S.J., Luis Fernando Granados; Campo Vasquez, Rafael

    2012-01-01

    Este articulo presenta los resultados de la investigacion realizada con el fin de caracterizar los avances teoricos, investigativos y/o de intervencion en resiliencia desde el ambito de las universidades en Colombia...

  6. First-Principles Modeling of Multiferroic RMn2O5

    Science.gov (United States)

    Cao, Kun; Guo, Guang-Can; Vanderbilt, David; He, Lixin

    2009-12-01

    We investigate the phase diagrams of RMn2O5 via a first-principles effective-Hamiltonian method. We are able to reproduce the most important features of the complicated magnetic and ferroelectric phase transitions. The calculated polarization as a function of temperature agrees very well with experiments. The dielectric-constant step at the commensurate-to-incommensurate magnetic phase transition is well reproduced. The microscopic mechanisms for the phase transitions are discussed.

  7. A neutron diffraction study of RMn2O5 multiferroics

    Science.gov (United States)

    Radaelli, P. G.; Chapon, L. C.

    2008-10-01

    The magnetic properties of RMn2O5 multiferroics as obtained by unpolarized and polarized neutron diffraction experiments are reviewed. We discuss the qualitative features of the magnetic phase diagram in both zero magnetic field and in field and analyze the commensurate magnetic structure and its coupling to an applied electric field. The origin of ferroelectricity is discussed based on calculations of the ferroelectric polarization predicted by different microscopic coupling mechanisms (exchange-striction and cycloidal spin-orbit models). A minimal model containing a small set of parameters is also presented in order to understand the propagation of the magnetic structure along the c-direction.

  8. Magnetic and ferroelectric properties of multiferroic RMn2O5

    Science.gov (United States)

    Noda, Y.; Kimura, H.; Fukunaga, M.; Kobayashi, S.; Kagomiya, I.; Kohn, K.

    2008-10-01

    The magnetic and ferroelectric properties of multiferroic RMn2O5 (R = Y, Tb, Ho, Er, Tm) are reviewed based on recent neutron diffraction and dielectric measurements. Successive phase transitions of magnetic and dielectric ordering were found to occur simultaneously in this system. The characteristic magnetic ordering of the system exhibits an incommensurate-commensurate phase transition, and again transitions to an incommensurate phase. Special attention is given to the magnetic structure in order to discuss the mechanism for the introduction of ferroelectric polarization. For all the compounds examined, the spin configuration for Mn4+ and Mn3+ ions in the commensurate magnetic phase, where spontaneous electric polarization occurs, was determined to be a transverse spiral spin structure propagating along the c-axis. By contrast, the alignment of the induced 4f moment of R3+ ions showed variation, depending on the character of each of the elements. Corresponding responses to external fields such as a magnetic field, hydrostatic pressure etc at low temperature are strongly dependent on the rare earth element present in the RMn2O5 system. The so-called colossal magnetoelectric effect in this system can be easily interpreted by the phase transition from the magnetic incommensurate and weak ferroelectric phase to the commensurate and ferroelectric phase.

  9. Cloverleaf domain patterns in multiferroic RMnO3 (R = Ho, Er, and Lu)

    Science.gov (United States)

    Horibe, Y.; Chae, S. C.; Lee, N.; Cheong, S.-W.

    2011-03-01

    Hexagonal RMn O3 (R=rare earths) exhibits a unique improper ferroelectricity induced by structural trimerization. Intriguing domain pattern associated with ferroelectricity and trimerization, so-called ``cloverleaf'' domain pattern, has been reported in YMn O3 In this talk, we will report the domain structures in a series of RMn O3 with different rare earth elements, obtained from the results of our transmission electron microscopy. Characteristic cloverleaf domain patterns are clearly observed in RMn O3 (R = Ho, Er, and Lu). The results imply that the cloverleaf domain pattern is a common domain feature in the hexagonal manganites.

  10. Electromagnons in multiferroic RMn2O5 compounds and their microscopic origin

    Science.gov (United States)

    Sushkov, A. B.; Mostovoy, M.; Valdés Aguilar, R.; Cheong, S.-W.; Drew, H. D.

    2008-10-01

    We summarize the existing experimental data on electromagnons in multiferroic RMn2O5 compounds, where R denotes a rare earth ion, Y or Bi, and discuss a realistic microscopic model of these materials based on the assumption that the microscopic mechanism of magnetically induced ferroelectricity and electromagnon absorption relies entirely on the isotropic Heisenberg exchange and magnetostrictive coupling of spins to a polar lattice mode and does not involve relativistic effects. This model explains many magnetic and optical properties of RMn2O5 manganites, such as the spin re-orientation transition, magnetically induced polarization, appearance of the electromagnon peak in the non-collinear spin state and the polarization of light for which this peak is observed. We compare experimental and theoretical results on electromagnons in RMn2O5 and RMnO3 compounds.

  11. Delirium and dementia in acute hospitals: assessing the impact of RMN input.

    Science.gov (United States)

    Law, Emma

    2008-11-01

    There is evidence that provision for the mental health needs of older people in acute hospitals is generally poor. This article describes a study undertaken over a nine-month period at Perth Royal Infirmary, a 317-bed district general hospital. The study sought to measure the impact of input from an RMN in an acute hospital setting and within a multidisciplinary liaison model. The article examines the implications, preparation, implementation and evaluation of RMN input, and the baseline knowledge and expectations of acute hospital staff when caring for patients with dementia and delirium.

  12. Studies of novel deuterides RMn2D6 (R — rare earth) compressed in DAC up to 30 GPa

    Science.gov (United States)

    Filipek, S. M.; Sugiura, H.; Paul-Boncour, V.; Wierzbicki, R.; Liu, R. S.; Bagkar, N.

    2008-07-01

    The exposure of RMn2 (C15 or C14 cubic Laves phase, where R = Y; Dy; Ho or Er) to high deuterium pressure leads to formation of novel, unique YMn2D6, DyMn2D6, HoMn2D6 and ErMn2D6 deuterides with cubic Fm-3m symmetry. In spite of different structures and molecular volumes of parent RMn2 compounds, the molar volumes of RMn2D6 deuterides are almost identical. In this paper, we present results of studies on RMn2Dx (where R = Y, Dy, Ho and Er) submitted to compression up to 30 GPa in diamond anvil cell (DAC) combined with energy dispersive X-ray diffraction. The EOS (equation of state) parameters of the above four RMn2D6 samples and YMn2Dx, with x RMn2D6 but very different than those of interstitial deuterides YMn2Dx (x RMn2D6 up to 30 GPa.

  13. I concetti di "materia", "forma" e "ordine" nel pensiero teorico musicale medievale e contemporaneo

    Directory of Open Access Journals (Sweden)

    Cecilia Panti

    2011-01-01

    Full Text Available La dimensione teorica della musica occidentale, nella sua evoluzione storica, ha inevitabilmente fatto uso di concetti essenziali alla definizione di come il suono è musicalmente organizzato o organizzabile. Fra questi, risultano imprescindibili le nozioni di materia, forma e ordine, che implicano rispettivamente, nei pur diversi ambiti linguistici e contesti storico-filosofici di riferimento, ciò di cui è fatta la musica, ciò a cui la materia sonora tende, e come tale tensione è realizzata. Scopo di questo contributo è una valutazione d’insieme sulla valenza filosofica e l’uso di tali concetti nel pensiero musicale occidentale altomedievale e in quello del Novecento, che nonostante la distanza cronologica presentano convergenze significative. Nel Medioevo, un lungo processo di elaborazione teorico-pratica permise la matematizzazione dello spazio (e, più tardi, anche del tempo musicale, attraverso l’adattamento di moduli melodici, trasmessi oralmente, alle strutture scalari desunte dalla teoria greco-boeziana. La forma e l’ordo musicali furono quindi riferiti ai criteri fisico-matematici atti a distinguere nella materia sonora, in sé disorganica e indefinita, ciò che è musicale da ciò che non lo è. Tale concezione sparisce con l’affermarsi del sistema tonale, ove il suono fisico è concepito come “pre-formato” e “pre-ordinato” nella gamma scalare e nei vincoli attrattivi “naturali” degli armonici. In conseguenza, i concetti di forma e ordine abbandonano il contesto acustico, andando a definire i criteri teorici della composizione artistica, in linea con l’idea filosofica del loro esprimere la coerenza logico-sintattica dell’“insieme organico” (la Formenlehre teorizzata da Widmann. Nell’ambito del pensiero musicale del Novecento, la crisi del sistema tonale e la messa a punto di nuove modalità e tecniche di produzione del suono hanno riorientato la valenza significante e l’uso di questi tre concetti

  14. Spin structure and magnetic frustration in multiferroic RMn2O5 (R=Tb,Ho,Dy)

    NARCIS (Netherlands)

    Blake, G.R.; Chapon, L.C.; Radaelli, P.G.; Park, S.; Hur, N.; Cheong, S-W.; Rodríguez-Carvajal, J.

    2005-01-01

    We have studied the crystal and magnetic structures of the magnetoelectric materials RMn2O5 (R=Tb,Ho,Dy) using neutron diffraction as a function of temperature. All three materials display incommensurate antiferromagnetic ordering below 40 K, becoming commensurate on further cooling. For R=Tb,Ho, a

  15. Refurbishment of the power supply and NMR systems; Renovation des alimentations et du systeme RMN

    Energy Technology Data Exchange (ETDEWEB)

    Dugay, G. [Grand Accelerateur National d`Ions Lourdes (GANIL), 14 - Caen (France)] [and others

    1998-12-31

    This paper summarises some of the first renovation performed on GANIL power converters, their control system and on magnetic field measurements. Among numerous actions undertaken the most important four, mentioned in the report are: remote control interfaces; current catchers; pulsed supplies; RMN system renovation 4 refs., 2 figs.

  16. Utilización de espectros de RMN bidimensionales en la deducción

    Directory of Open Access Journals (Sweden)

    Juan C. Martínez Valderrama

    2010-06-01

    Full Text Available Se ilustra la metodología para la deducción total de la estructura de una molécula orgánica desconocida, del tipo piranocoumarina (5-metoxiseselin, utilizando espectros de RMN bidimensionales de diferentes clases: COSY H-H, NOESY y HETCOR C-H a un enlace y a larga distancia.

  17. Correlation between magnon and magnetic symmetries of hexagonal RMnO3 (R = Er, Ho, Lu)

    Science.gov (United States)

    Nguyen, Thi Minh Hien; Nguyen, Thi Huyen; Chen, Xiang-Bai; Park, Yeonju; Jung, Young Mee; Lee, D.; Noh, T. W.; Cheong, Sang-Wook; Yang, In-Sang

    2016-11-01

    The correlation between the magnon scattering and the magnetic symmetries of hexagonal RMnO3 (R = Er, Ho) thin films and LuMnO3 single crystal was studied through the 2D Correlation Spectroscopy (2D COS) and Perturbation-Correlation Moving Window 2D (PCMW2D) Correlation Spectroscopy which were performed on the temperature-dependent Raman spectra of RMnO3 (R = Er, Ho, Lu). From the Raman spectra, we observed much stronger intensity and more asymmetrical magnon peak in LuMnO3 single crystal than in ErMnO3 and HoMnO3 thin films. While the ratio between magnon and phonon's linewidth of LuMnO3 and HoMnO3 display an anomalous behavior, that ratio of ErMnO3 is almost stable. The result from PCMW2D also supports these results. In addition, our 2D COS analysis showed that there are more overlap peaks in broad four-spin flipping magnon peak in LuMnO3 than that in ErMnO3 and HoMnO3. The differences of hexagonal RMnO3 (R = Er, Ho, Lu) in magnon scattering are very similar to the actual differences of the magnetic symmetries of these compounds. Therefore, we suggest that the magnon scattering of hexagonal RMnO3 is strongly correlated with the magnetic symmetries of these materials.

  18. NDLS-3000配接GR-DEV-Rmg-Rmn-CAL组合仪%NDLS 3000 Combination Instrument matched with GR-DEV-Rmg-Rmn-CAL

    Institute of Scientific and Technical Information of China (English)

    陈金宏; 刘素洁; 刘国权; 徐涛

    2003-01-01

    首先简单介绍NDLS-3000的特点和华北油田砂泥岩剖面测井项目,分析其他组合测井所存在的问题.再详细说明在NDLS-3000网络双测井系统上配接GR_DEV_Rmg_Rmn_CAL组合仪的方法,包括井下仪器的连接方法和组合测井软件的编制与使用方法.

  19. Spiral Spin Structure in the Commensurate Magnetic Phase of Multiferroic RMn2O5

    Science.gov (United States)

    Kimura, Hiroyuki; Kobayashi, Satoru; Fukuda, Yoshikazu; Osawa, Toshihiro; Kamada, Youichi; Noda, Yukio; Kagomiya, Isao; Kohn, Kay

    2007-07-01

    Crystal and magnetic structure analyses have been performed for single crystals of multiferroic materials RMn2O5 (R = Y, Ho, Er) using the neutron diffraction technique. For all the compounds, the magnetic structure in the commensurate magnetic phase, where spontaneous electric polarization occurs, was determined to be a transverse spiral spin structure propagating along the c-axis. The results demonstrate that the spin configuration for Mn4+ and Mn3+ ions is essentially the same in all three materials, suggesting that the ferroelectricity of the commensurate magnetic phase originates from the spin configurations of Mn ions. By contrast, the alignment of the induced 4 f-moment of Ho3+ ions is quite different from that of Er3+ ions, which might give a rich variety of magnetic field response for magnetic and dielectric properties in the RMn2O5 system.

  20. Measurement of complicated temperature-dependent polarization of multiferroic RMn2O5

    Science.gov (United States)

    Fukunaga, Mamoru; Noda, Yukio

    2011-09-01

    We have measured the temperature-dependent electric polarization P(T) of multiferroic rare-earth (R) manganese oxides RMn2O5 using both typical pyroelectric measurements and hysteresis loops with the double-wave method (DWM), and revealed the complicated behavior of the P(T). RMn2O5 single crystal samples often exhibit a tendency to macroscopically polarize without applying an external electric field. We have found that the tendency appeared in P(T) by the pyroelectric measurement can be measured by the DWM loops. The tendency to polarize is equivalent to asymmetric non-hystersis loops obtained by the DWM. We clarify the relationship between P(T) by pyroelectric measurement and that by the DWM loops, which can warrant the measured P(T).

  1. An effective model of magnetoelectricity in multiferroics RMn2O5

    Science.gov (United States)

    Fang, Chen; Hu, Jiangping

    2008-06-01

    An effective model is developed to explain the phase diagram and the mechanism of magnetoelectric coupling in multiferroics, RMn2O5. We show that the nature of magnetoelectric coupling in RMn2O5 is a coupling between two Ising-type orders, namely, the ferroelectric order in the b-axis, and the.coupled magnetic order between two frustrated antiferromagnetic chains. The frustrated magnetic structure drives the system to a commensurate-incommensurate phase transition, which can be understood as a competition between a collinear order stemming from the "order by disorder" mechanism and a chiral symmetry order. The low-energy excitation is calculated and it quantitatively matches experimental results. Distinct features and the effects of external magnetic field in the electromagnon spectra in the incommensurate phase are predicted.

  2. Evidence for room temperature electric polarization in RMn(2)O(5) multiferroics.

    Science.gov (United States)

    Balédent, V; Chattopadhyay, S; Fertey, P; Lepetit, M B; Greenblatt, M; Wanklyn, B; Saouma, F O; Jang, J I; Foury-Leylekian, P

    2015-03-20

    It is established that the multiferroics RMn(2)O(5) crystallize in the centrosymmetric Pbam space group and that the magnetically induced electric polarization appearing at low temperature is accompanied by a symmetry breaking. However, both our present x-ray study-performed on compounds with R=Pr,Nd,Gd,Tb, and Dy-and first-principles calculations unambiguously rule out this picture. Based on structural refinements, geometry optimization, and physical arguments, we demonstrate in this Letter that the actual space group is likely to be Pm. This turns out to be of crucial importance for RMn(2)O(5) multiferroics since Pm is not centrosymmetric. Ferroelectricity is thus already present at room temperature, and its enhancement at low temperature is a spin-enhanced process. This result is also supported by direct observation of optical second harmonic generation. This fundamental result calls into question the actual theoretical approaches that describe the magnetoelectric coupling in this multiferroic family.

  3. Lattice dynamics and spin-phonon interactions in multiferroic RMn2O5: Shell model calculations

    Science.gov (United States)

    Litvinchuk, A. P.

    2009-08-01

    The results of the shell model lattice dynamics calculations of multiferroic RMn2O5 materials (space group Pbam) are reported. Theoretical even-parity eigenmode frequencies are compared with those obtained experimentally in polarized Raman scattering experiments for R=Ho,Dy. Analysis of displacement patterns allows to identify vibrational modes which facilitate spin-phonon coupling by modulating the Mn-Mn exchange interaction and provides explanation of the observed anomalous temperature behavior of phonons.

  4. Classification and Interpretation of the Polarization of Multiferroic RMn2O5

    Science.gov (United States)

    Fukunaga, Mamoru; Noda, Yukio

    2010-05-01

    We have collected and compared temperature-dependent polarization data of multiferroic RMn2O5 for 11 kinds of rare earths (R) from the literature and our own measurements. Although the reported data are inconsistent, it was found that the maximum polarization values for R=Y, Dy, Ho, Er, and Tm are almost equal above 30 K except for the phase transition temperature where the polarization disappears. The findings suggest a standard polarization value for RMn2O5 of 100-120 nC/cm2 at 30 K in a commensurate magnetic (CM) phase. We discuss the nature and issues of the measured polarization of RMn2O5 from the data and our detailed measurement results for YMn2O5. Temperature-dependent ferroelectric hysteresis loops of YMn2O5 by the double-wave method reveal that an antiferroelectric-like high-temperature incommensurate magnetic (ICM) phase and a ferroelectric low-temperature ICM phase, while the intermediate CM phase is ferrielectric.

  5. Calculo de la Barra Antivuelco de un Vehículo Automotor.

    Directory of Open Access Journals (Sweden)

    Javier García de la Figal

    2005-09-01

    Full Text Available El presente trabajo trata acerca del calculo de la barra antivuelco del FORD modelo A, desarrollado por elInstituto de Desarrollo Automotriz, IDA, teniendo en cuenta las fuerzas que la cinta de seguridad de losautomovilistas, ejerce sobre la citada barra, ante un choque que provoca una aceleración de 20 g en elvehículo. El calculo se hace mediante la confección de un modelo de elementos finitos de la barra y lacarrocería, para lo cual se hace uso de un programa profesional de elementos finitos.Se determinan los esfuerzos máximos y los equivalentes, tanto de las partes metálicas del sistema, queson fundamentalmente tubos de acero, como de las partes de material compuesto (poliéster con fibras devidrio E, propios de la carrocería del vehículo. Todo lo cual permite hacer los cálculos y comprobacionesa resistencia de todo el conjunto. Así mismo, se determinan los desplazamientos en todos los sentidos detodos las partes del sistema, para poder realizar los correspondientes análisis de rigidez.El objetivo final de todos los análisis es determinar lo adecuado o no de las soluciones y materialespropuestos para el sistema, bajo la acción de la citada carga de impacto.

  6. The pseudogap and anisotropic thermal expansion in RMn(4)Al(8) (R = La,Y,Lu and Sc).

    Science.gov (United States)

    Muro, Y; Nakamura, H; Kohara, T

    2006-04-26

    The temperature dependence of the magnetic susceptibility shows a broad maximum at ∼550 and 630 K for LuMn(4)Al(8) and ScMn(4)Al(8), respectively, which can be interpreted as due to the presence of a pseudogap in the effective bands as in LaMn(4)Al(8) and YMn(4)Al(8). The anisotropic thermal expansion observed for RMn(4)Al(8) (R = La, Y, Lu and Sc) and the sensitive volume dependence of the gap width throughout the RMn(4)Al(8) system suggest dominant magnetic coupling in Mn spin chains along the c axis.

  7. Local structure of multiferroic RMn 2O 5: Important role of the R site

    Science.gov (United States)

    Tyson, T. A.; Chen, Z.; DeLeon, M. A.; Yoong, S.; Cheong, S.-W.

    2009-06-01

    The temperature and magnetic field dependent local structure of RMn 2O 5 systems was examined. While no significant displacements of the Mn ions are observed, it is found that the R-O distribution exhibits changes at low temperature which are possibly related to the changes in the electric polarization. Density functional computations are used to explore the system dynamics and to link the local structural measurements with anomalous changes in the infrared absorption spectra. The anomalous R-O distribution and observed coupling to magnetic fields point to the need to properly treat the 4f electrons on the R sites in these systems.

  8. Antiferromagnet-long-period structure phase transition in RMn2O5 oxides

    Science.gov (United States)

    Men'shenin, V. V.; Nikolaev, V. V.; Dmitriev, A. V.

    2011-07-01

    An analysis of the magnetic phase transition from an antiferromagnetic into an incommensurate phase in oxides RMn2O5 has been performed. It has been shown that this is a second-order phase transition and that it can occur through one of complete irreducible representations of the space group Pbam, i.e., without a decrease in the symmetry of the crystal lattice. It has been established that the decrease in the electric polarization of the oxides in this transition is due to the development of long-period magnetic ordering.

  9. Interrelation between the soliton lattice and electric polarization in RMn2O5 oxides

    Science.gov (United States)

    Men'shenin, V. V.

    2009-02-01

    Magnetic transitions from the paramagnetic state to an incommensurate magnetic structure and then to an ordered phase with long-range antiferromagnetic order in RMn2O5 (R is a rare-earth ion) oxides are analyzed. It is shown that a transition from the paramagnetic to the incommensurate phase is associated with exchange as well as relativistic interactions and can be described, apart from the basic magnetic order parameter, by an associated order parameter (viz., electric polarization along the y axis of the crystal). As a result of such a transition, the emergence of electric polarization in the crystal is not accompanied by a change in crystal symmetry.

  10. Insights on Electric Polarization in E-type RMnO3

    Science.gov (United States)

    Wu, Tao; Tyson, Trevor A.; Chen, Haiyan; Chen, Zhiqiang; Tappero, Ryan; Ahn, Keun H.; Kim, Sungbaek; Cheong, Sang-Wook

    2013-03-01

    Orthorhombic perovskite E-type RMnO3 multiferroic systems were prepared by high pressure synthesis and solid state reaction. High pressure synchrotron x-ray diffraction and x-ray absorption spectroscopy measurements were performed to explore the structural changes. The influence of the pressure on the electrical polarization is discussed. Theoretical analysis is used to predict pressure dependence of the polarization from the structural data derived from the refinements. This work is supported by DOE Grant DE-FG02-07ER46402.

  11. Unusual Evolution of the Magnetic Interactions versus Structural Distortions in RMnO3 Perovskites

    Science.gov (United States)

    Zhou, J.-S.; Goodenough, J. B.

    2006-06-01

    We report the refinement of x-ray powder diffraction together with magnetic and thermal conductivity measurements made on the entire family of RMnO3 perovskites prepared by melt growth or under high pressure. Analysis of the data has identified the origin of the transition from type-A to type-E magnetic order as a competition between t-orbital and e-orbital spin-spin interactions within each Mn-O-Mn bond in the (001) planes, the e-orbital interactions decreasing with decreasing R3+-ion size.

  12. Studies of novel deuterides RMn{sub 2}D{sub 6} (R - rare earth) compressed in DAC up to 30 GPa

    Energy Technology Data Exchange (ETDEWEB)

    Filipek, S M; Wierzbicki, R [Institute of Physical Chemistry PAS., ul. Kasprzaka 44, 01-224 Warsaw (Poland); Sugiura, H [Graduate School of Integrated Sci., Yokohama City University, 22-2 Seta, Kanazawa-ku, Yokohama 236-0027 (Japan); Paul-Boncour, V [Chimie Metallurgique des Terres Rares, ICMPE, GLVT, 2-8 rue Henri Dunant, 94320 Thiais Cedex (France); Liu, R S; Bagkar, N [Department of Chemistry, National Taiwan University, Taipei 106, Taiwan (China)], E-mail: smf@ichf.edu.pl

    2008-07-15

    The exposure of RMn{sub 2} (C15 or C14 cubic Laves phase, where R = Y; Dy; Ho or Er) to high deuterium pressure leads to formation of novel, unique YMn{sub 2}D{sub 6}, DyMn{sub 2}D{sub 6}, HoMn{sub 2}D{sub 6} and ErMn{sub 2}D{sub 6} deuterides with cubic Fm-3m symmetry. In spite of different structures and molecular volumes of parent RMn{sub 2} compounds, the molar volumes of RMn{sub 2}D{sub 6} deuterides are almost identical. In this paper, we present results of studies on RMn{sub 2}Dx (where R = Y, Dy, Ho and Er) submitted to compression up to 30 GPa in diamond anvil cell (DAC) combined with energy dispersive X-ray diffraction. The EOS (equation of state) parameters of the above four RMn{sub 2}D{sub 6} samples and YMn{sub 2}D{sub x}, with x {<=} 4 are compared. The EOS parameters of YMn{sub 2}D{sub 6} are very similar to those of other RMn{sub 2}D{sub 6} but very different than those of interstitial deuterides YMn{sub 2}D{sub x} (x {<=} 4). The phase transition or segregation was not detected in RMn{sub 2}D{sub 6} up to 30 GPa.

  13. Molecular-spin dynamics study of electromagnons in multiferroic RMn2O5

    Science.gov (United States)

    Cao, Kun; Guo, G.-C.; He, Lixin

    2012-05-01

    We investigate the electromagnon in magnetoferroelectrics RMn2O5 using combined molecular-spin dynamics simulations. We confirm that the origin of the electromagnon modes observed in the optical spectra is due to the exchange-striction interaction between the magnons and the phonons, and the dielectric step at the magnetic phase transition is due to the appearance of the electromagnon in the low-temperature phase in these materials. The magnetic anisotropy breaks the rotational symmetry of the magnetic structures and, as a result, the electromagnon splits into three modes in RMn2O5. We find that the electromagnon frequencies are very sensitive to the magnetic wavevector along the a direction qx. Therefore, the electromagnon frequencies of TmMn2O5 (qx ˜ 0.467) are expected to be much higher than those of other materials of the family, such as R= Tb, Y, Ho, etc (qx ˜ 0.48). We further calculate the electromagnons in the magnetic field, and find a new mode appearing in the magnetic field. Although the modes’ frequencies change significantly under magnetic field, the total static dielectric constant contributed from the electromagnons does not change much in the magnetic field, suggesting that the colossal magnetodielectric effects in these materials may not be caused by the electromagnons.

  14. Nature of unusual spontaneous and field-induced phase transitions in multiferroics RMn 2O 5

    Science.gov (United States)

    Pyatakov, A. P.; Kadomtseva, A. M.; Vorob'ev, G. P.; Popov, Yu. F.; Krotov, S. S.; Zvezdin, A. K.; Lukina, M. M.

    2009-04-01

    Complex magnetic, magnetoelectric and magnetoelastic studies of spontaneous and field-induced phase transitions in TmMn 2O 5 were carried out. In the vicinity of spontaneous phase transition temperatures (35 and 25 K) the magnetoelectric and magnetoelastic dependences demonstrated the jumps of polarization and magnetostriction induced by the field ˜150 kOe. These anomalies can be attributed to the influence of magnetic field on the conditions of incommensurate-commensurate phase transition at 35 K and the reverse one at 25 K. In b-axis dependences the magnetic field-induced spin-reorientation phase transition was also observed below 20 K. Finally the magnetoelectric anomaly associated with metamagnetic transition is observed below the temperature of rare-earth subsystem ordering at relatively small critical fields of 5 kOe. This variety of spontaneous and induced phase transitions in RMn 2O 5 stems from the interplay of three magnetic subsystems: Mn 3+, Mn 4+, R 3+. The comparison with YMn 2O 5 highlights the role of rare earth in low-temperature region (metamagnetic and spin-reorientation phase transitions), while the phase transition at higher temperatures between incommensurate and commensurate phases should be ascribed to the different temperature dependences of Mn 3+ and Mn 4+ ions. The strong correlation of magnetoelastic and magnetoelectric properties observed in the whole class of RMn 2O 5 highlights their multiferroic nature.

  15. Spin-driven ferroelectricity in the multiferroic compounds of RMn2O5

    Science.gov (United States)

    Kimura, H.; Noda, Y.; Kohn, K.

    2009-04-01

    Neutron diffraction studies under magnetic field as well as under hydrostatic pressure for microscopic magnetism on multiferroic RMn2O5 ( R=rare-earth, Bi, and Y) are reviewed to discuss about the relevance between the magnetic property and dielectric property in detail. Without any external fields, a series of RMn2O5 shows successive magnetic phase transitions of incommensurate-commensurate-incommensurate as temperature decreases, in which the dielectric phase transitions concomitantly occur. At the lowest temperature phase of HoMn2O5, the magnetic transition from the incommensurate phase to the commensurate one is induced by applying both magnetic field and hydrostatic pressure. At this field-induced magnetic transition, a spontaneous electric polarization simultaneously induced, indicating that the ferroelectricity in this material is magnetically controlled. Competition of multiple magnetic ground states due to intensional magnetic frustration in this system can be easily tuned by applying external fields, which give rise to the rich variety of spin-driven dielectric transitions.

  16. Double Double Cation Order in the High-Pressure Perovskites MnRMnSbO6.

    Science.gov (United States)

    Solana-Madruga, Elena; Arévalo-López, Ángel M; Dos Santos-García, Antonio J; Urones-Garrote, Esteban; Ávila-Brande, David; Sáez-Puche, Regino; Attfield, J Paul

    2016-08-01

    Cation ordering in ABO3 perovskites adds to their chemical variety and can lead to properties such as ferrimagnetism and magnetoresistance in Sr2 FeMoO6 . Through high-pressure and high-temperature synthesis, a new type of "double double perovskite" structure has been discovered in the family MnRMnSbO6 (R=La, Pr, Nd, Sm). This tetragonal structure has a 1:1 order of cations on both A and B sites, with A-site Mn(2+) and R(3+) cations ordered in columns and Mn(2+) and Sb(5+) having rock salt order on the B sites. The MnRMnSbO6 double double perovskites are ferrimagnetic at low temperatures with additional spin-reorientation transitions. The ordering direction of ferrimagnetic Mn spins in MnNdMnSbO6 changes from parallel to [001] below TC =76 K to perpendicular below the reorientation transition at 42 K at which Nd moments also order. Smaller rare earths lead to conventional monoclinic double perovskites (MnR)MnSbO6 for Eu and Gd.

  17. Magnetic order and ferroelectricity in RMnO(3) multiferroic manganites : coupling between R- and Mn-spins

    NARCIS (Netherlands)

    Aliouane, N.; Prokhnenko, O.; Feyerherm, R.; Mostovoy, M.; Strempfer, J.; Habicht, K.; Rule, K. C.; Dudzik, E.; Maljuk, A.; Argyriou, D. N.

    2008-01-01

    Combining polarized and unpolarized neutron scattering techniques with x-ray resonant magnetic scattering we have studied the coupling between the Mn- and R- spin- ordering in the multiferroic RMnO(3), R = Tb and Dy. Polarized neutron diffraction reveals the moment orientation associated with the va

  18. (H,T,P) Phase Diagrams in Multiferroics: RMnO3, RMn2O5 (R = Rare Earth) and Ni3V2O8

    Science.gov (United States)

    Chu, Paul C. W.

    2006-03-01

    Recently, great interest has been generated in the class of materials known as multiferroics (MF), which exhibit the simultaneous occurrence of two or more of the following properties, namely, ferro(anti) magnetic, ferro(anti) electric, ferroelastic, ferroacoustic, and ferroplastic. A subset of MF, known as magnetoelectrics (ME), in which the magnetic and ferroelectric orders coexist, can display the ME-effect where their magnetic and dielectric properties can be affected by an electric and a magnetic field, respectively. The attention first generated in the 60's waned due to the smallness of the effect. However, the situation has drastically changed in recent years due to the observation of a giant ME-effect [1]. Complex diagrams have been induced by magnetic field in the hexagonal single-crystalline rare-earth manganites RMnO3 [2] and the Kagome-staircase compound Ni3V2O8 [3], as evidenced by anomalies in their dielectric constant, specific heat, magnetic susceptibility, and thermal expansion coefficients at the phase boundaries. Some of these anomalies occur simultaneously. In this talk, our results of the dielectric, magnetic, calorimetric, and dilatometric properties of RMnO3 (R = Ho, Y, Dy, Er, Tm, and Tb), HoMn2O5 and Ni3V2O8 at ambient pressure in different magnetic fields up to 7 T and some under high pressures up to 2 GPa will be presented. Analysis of the anomalies and examination of the pressure effects on the phase boundaries demonstrate the critical role of strong spin-phonon coupling in the ME-effect and the richness of physics in the study of ME phase diagrams. Possible avenues to further enhance the ME-effect will be discussed. [1] see for example N. Hur et al., PRL 93, 107207 (2004). [2] B. Lorenz et al., PRL 92, 087204 (2004); B. Lorenz et al., PRB 71, 014438 (2005); C. dela Cruz et al., PRB 71, 060407(R) (2005); F. Yen et al., PRB 71, 180407(R) (2005). [3] G. Lawes et al., cond-mat/0503385.

  19. Ferrielectricity in DyMn2O5: A golden touchstone for multiferroicity of RMn2O5 family

    Science.gov (United States)

    Liu, J.-M.; Dong, S.

    2015-06-01

    The RMn2O5 manganite compounds represent one class of multiferroic family with magnetic origins, which has been receiving continuous attention in the past decade. So far, our understanding of the magnetic origins for ferroelectricity in RMn2O5 is associated with the nearly collinear antiferromagnetic structure of Mn ions, while the exchange striction induced ionic displacements are the consequence of the spin frustration competitions. While this scenario may be applied to almost all RMn2O5 members, its limitation is either clear: the temperature-dependent behaviors of electric polarization and its responses to external stimuli are seriously materials dependent. These inconsistences raise substantial concern with the state-of-the-art physics of ferroelectricity in RMn2O5. In this mini-review, we present our recent experimental results on the roles of the 4f moments from R ions which are intimately coupled with the 3d moments from Mn ions. DyMn2O5 is a golden figure for illustrating these roles. It is demonstrated that the spin structure accommodates two nearly collinear sublattices which generate respectively two ferroelectric (FE) sublattices, enabling DyMn2O5 an emergent ferrielectric (FIE) system rarely identified in magnetically induced FEs. The evidence is presented from several aspects, including FIE-like phenomena and magnetoelectric responses, proposed structural model, and experimental check by nonmagnetic substitutions of the 3d and 4f moments. Additional perspectives regarding possible challenges in understanding the multiferroicity of RMn2O5 as a generalized scenario are discussed.

  20. Nuclear quadrupole interaction studies of C15 RMn2 hydrides ( R=Y ,Gd,Tb,Dy)

    Science.gov (United States)

    Forker, M.; Bedi, S. C.; Euler, H.

    2008-09-01

    The nuclear electric quadrupole interaction (QI) of the probe nucleus I111n/C111d in the paramagnetic phase of the C15 rare earth (R) manganese hydrides (deuterides) RMn2H(D)x , with R=Y , Gd, Tb, and Dy, has been investigated by perturbed angular-correlation spectroscopy. The QI between the C111d quadrupole moment and the electric-field gradient (EFG) at the probe nucleus on the Mn site has been measured as a function of temperature in TbMn2H(D)x in the concentration range 0≤x≤4.3 and in RMn2H(D)x , R=Y ,Gd,Dy at the highest H content of xtilde 4.3 . The relative temperature dependence of the EFG in the parent compounds RMn2 is twice as strong as in isostructural RAl2 which can be related to differences in the Debye temperatures resulting from different radius ratios rR/rMn and rR/rAl [Joseph-Gschneidner postulate, Scr. Metall.2, 631 (1968)]. Hydrogenation of RMn2 increases the magnitude of the EFG by a factor of 2 between x=0 and x=4.3 but leaves the relative temperature dependence almost unchanged. Only at concentrations x>3.6 the temperature coefficient of the QI is significantly larger than in uncharged RMn2 . These results are compared with the much stronger concentration dependence and the anomalous temperature dependence of the QI of C111d in the C15 hydrides HfV2Hx . Evidence for an exceptionally high H mobility in TbMn2Hx is presented. The measurements provide information on structural changes and magnetic ordering temperatures at different H concentrations.

  1. Algorithm for the calculation of a steam generator efficiency; Algoritmo para el calculo de la eficiencia de un generador de vapor

    Energy Technology Data Exchange (ETDEWEB)

    Franco, David; Ambriz, Juan Jose; Romero Paredes, Hernando [Universidad Autonoma Metropolitana-Iztapalapa, Mexico, D. F. (Mexico)

    1994-12-31

    The efficiency calculation of steam generators is not always simple. The purpose of this paper is to propose an algorithm for the calculation of steam generators efficiency, easy to understand and carry out, in the form of a series of steps to be followed. It takes as starting point that the person in charge of applying these calculations has knowledge of the combustion processes and thermodynamic principles that rule such processes. [Espanol] El calculo de la eficiencia de los generadores de vapor no siempre es sencillo, el presente trabajo tiene como objetivo el de proponer un algoritmo de calculo de eficiencia de generadores de vapor, el cual sea facil de entender y de llevar a cabo, en forma de una serie de pasos a seguir. Se toma como punto de partida, que la persona encargada de aplicar estos calculos tenga el conocimiento de los procesos de combustion y principios termodinamicos que rigen tales procesos.

  2. Spin chirality and electric polarization in multiferroic compounds RMn2O5 ( R=Ho, Er)

    Science.gov (United States)

    Wakimoto, Shuichi; Kimura, Hiroyuki; Fukunaga, Mamoru; Nishihata, Keisuke; Takeda, Masayasu; Kakurai, Kazuhisa; Noda, Yukio; Tokura, Yoshinori

    2009-09-01

    Polarized neutron diffraction experiments have been performed on multiferroic materials RMn2O5 ( R=Ho, Er) under electric fields in the ferroelectric commensurate (CM) and the low-temperature incommensurate (LT-ICM) phases, where the former has the highest electric polarization and the latter has reduced polarization. It is found that, after cooling in electric fields down to the CM phase, the magnetic chirality is proportional to the electric polarization. Also we confirmed that the magnetic chirality can be switched by the polarity of the electric polarization in both the CM and LT-ICM phases. These facts suggest an intimate coupling between the magnetic chirality and the electric polarization. However, upon the transition from the CM to LT-ICM phase, the reduction of the electric polarization is not accompanied by any reduction of the magnetic chirality, implying that the CM and LT-ICM phases contain different mechanisms of the magnetoelectric coupling.

  3. Double-flat-spiral magnetic structures: Theory and application to the RMn6X6 compounds

    Science.gov (United States)

    Rosenfeld, E. V.; Mushnikov, N. V.

    2008-05-01

    We studied magnetic structure of a layered magnetic material, the lattice of which consists of magnetic layers separated by alternating non-magnetic layers (slabs) of two different types. For such structure, the exchange integrals between the nearest magnetic layers separated by different slabs may have different values, while the next-nearest neighbor exchange integral is the same for all magnetic layers. We developed a model based on three different interlayer exchange integrals. In the framework of this model we analyzed conditions of the appearance of a magnetic structure of the double-flat-spiral type and its distortion in external magnetic field. The results are most obtained in the analytical form. The model was applied to analyze the magnetic structure and magnetization process of the RMn6X6 ( R=Y, Sc, Lu; X=Sn, Ge) compounds with the layered crystal structure.

  4. Multiferroic phase transitions in manganites RMnO3:A two-orbital double exchange simulation

    Institute of Scientific and Technical Information of China (English)

    Tao Yong-Mei; Lin Lin; Dong Shuai; Liu Jun-Ming

    2012-01-01

    The semi-quantum two-orbital exchange model is used to investigate the effect of smal1 rare-earth ion substitution on orthorhombic RMnO3 with A-type antiferromagnetic order,using the Monte Carlo algorithm,exact diagonalization,and zero-temperature optimization approaches.It is revealed that the substitution results in a rich multiferroic phase diagram where the coexisting A-type antiferromagnetic phase and spiral spin phase,pure spiral spin phase,coexisting spiral spin phase,the E-type antiferromagnetic phase,and the pure E-type antiferromagnetic phase emerge in sequence.The multiferroic phase transitions modulate substantially the electric polarization,which is consistent qualitatively with recent experiments.

  5. Model for twin electromagnons and magnetically induced oscillatory polarization in multiferroic RMnO3

    Science.gov (United States)

    de Sousa, Rogério; Stenberg, Markku

    2010-03-01

    We propose a model [1] for the pair of electromagnon excitations observed in the class of multiferroic materials RMnO3 (R is a rare-earth ion). The model is based on a harmonic cycloid ground state interacting with a zone-edge magnon and its twin excitation separated in momentum space by two times the cycloid wave vector. The pair of electromagnons is activated by cross coupling between magnetostriction and spin-orbit interactions. Remarkably, the spectral weight of the twin electromagnon is directly related to the presence of a magnetically induced oscillatory polarization in the ground state. This leads to the surprising prediction that TbMnO3 has an oscillatory polarization with amplitude 50 times larger than its uniform polarization. [4pt] [1] M.P.V. Stenberg and R. de Sousa, Phys. Rev. B 80, 094419 (2009) (Editors' suggestion).

  6. Hexagonal frustrated RMnO3 manganites (R = Y, Lu) under high pressure

    Science.gov (United States)

    Kozlenko, D. P.; Kichanov, S. E.; Lee, S.; Park, J.-G.; Glazkov, V. P.; Savenko, B. N.

    2007-05-01

    The crystalline and magnetic structures of YMnO3 and LuMnO3 hexagonal manganites under pressures of 0 6 GPa and in the temperature range 10 295 K have been investigated by neutron diffraction. Application of pressure leads to a significant decrease in the ordered magnetic moment of Mn ions (at T = 10 K) from 3.27 (0 GPa) to 1.52 μB (5 GPa) for YMnO3 and from 2.48 (0 GPa) to 1.98 μB (6 GPa) for LuMnO3. Under high pressures, spin reorientation of Mn magnetic moments and a change in the symmetry of the antiferromagnetic structure are observed in YMnO3. The relationship between the triangular lattice distortion parameter and the symmetry of the triangular antiferromagnetic state of RMnO3 hexagonal manganites is discussed.

  7. Neutron diffraction studies of nanoparticle RMnO{sub 3} compounds (R=Pr, Nd)

    Energy Technology Data Exchange (ETDEWEB)

    Baran, S., E-mail: stanislaw.baran@uj.edu.pl [M. Smoluchowski Institute of Physics, Jagiellonian University, Reymonta 4, PL-30 059 Kraków (Poland); Dyakonov, V. [Institute of Physics, PAS, Al. Lotników 32/46, PL-02-668 Warszawa (Poland); A. A. Gałkin Donetsk Physico-Technical Institute, National Academy of Sciences of Ukraine, 72 R. Luxembourg Str., Donetsk 83114 (Ukraine); Hofmann, T.; Hoser, A. [Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Hahn-Meitner Platz 1, D-14 109 Berlin (Germany); Penc, B. [M. Smoluchowski Institute of Physics, Jagiellonian University, Reymonta 4, PL-30 059 Kraków (Poland); Kravchenko, Z. [A. A. Gałkin Donetsk Physico-Technical Institute, National Academy of Sciences of Ukraine, 72 R. Luxembourg Str., Donetsk 83114 (Ukraine); Szytuła, A. [M. Smoluchowski Institute of Physics, Jagiellonian University, Reymonta 4, PL-30 059 Kraków (Poland)

    2013-10-15

    The neutron diffraction measurements of the nano-size RMnO{sub 3} (R=Pr, Nd) manganites have been performed. The obtained results indicate that these compounds crystallize in the orthorhombic crystal structure described by the space group Pnma. Low temperature data indicate both the absence of a long-range magnetic order down to 1.5 K in the PrMnO{sub 3} sample annealed at 800 °C and the C{sub x}F{sub y} magnetic structure with a very low value of the Mn magnetic moment as compared with bulk sample in the sample annealed at 900 °C. In the NdMnO{sub 3} samples annealed at 850 °C and 900 °C the magnetic order is described by the C{sub x}F{sub y} mode in the Mn sublattice and the F{sub y} mode in the Nd sublattice. The values of the Mn and Nd magnetic moments are lower that those in a bulk sample. Based on the model proposed in López-Quintela et al. [1] and Balcells et al. [2] the thickness of nonmagnetic shell was determined to be 7.1(4) nm in PrMnO{sub 3} and 4.6(5) nm in both the NdMnO{sub 3} compounds. - Highlights: • Magnetic structures of nanoparticle RMnO{sub 3} (R = Pr, Nd) samples have been determined. • The results have been compared with those obtained for polycrystalline samples. • According to the model in Refs. [1,2] the thickness of nonmagnetic shell has been found.

  8. Large dielectric permittivity in the paraelectric RMn2O5 with R=Tb, Dy, and Er

    Science.gov (United States)

    Han, T. C.; Lin, J. G.; Kuo, K. M.; Chern, G.

    2008-04-01

    The complex dielectric permittivities (ɛ',ɛ″) of RMn2O5 (R =Tb, Dy, and Er) are measured in the temperature range of 78-328 K with frequencies ranging from 100 Hz to 1 MHz. A large real part of the dielectric constant ɛ' (40-140) is observed at room temperature in all three samples studied. These values are higher than the peak value found at the ferroelectric transition of RMn2O5 single crystals. Our results reveal that high dielectric permittivities are related to thermally activated dipolar motions with activation energies of ˜300 meV and a relaxation frequency of ˜3×1012 Hz. The possible relation between the high dielectric permittivity and the size effect of R ions based on the spin-phonon interaction is suggested.

  9. Sintese de prolinas modificadas a partir de enecarbamato endociclico e estudo do equilibrio rotacional da ligação N-C(O) de seus derivados N-metoxicarbonilados por RMN 1H e calculos ab initio

    OpenAIRE

    Italo Jose da Cruz Rigotti

    2003-01-01

    Resumo: Uma série de 4,5-metanoprolinas foi preparada a partir da adição de espécies carbenóides ao N-carbometóxi-4,5-desidroprolinato de metila. Em condições de Simmons-Smith modificadas, obtiveram-se, após, 96 horas, dois produtos na proporção de 1:2 (determinado por CG) em 50% de rendimento. Sendo majoritário o produto que possui o grupamento metileno do ciclopropano cis ao éster do anel pirrolidínico. A adição de diclorocarbeno à olefina forneceu produtos com estereoquímica relativa cis e...

  10. Hexagonal versus perovskite phase of manganite RMnO3 (R=Y,Ho,Er,Tm,Yb,Lu)

    Science.gov (United States)

    Zhou, J.-S.; Goodenough, J. B.; Gallardo-Amores, J. M.; Morán, E.; Alario-Franco, M. A.; Caudillo, R.

    2006-07-01

    The floating-zone method and high-pressure synthesis have been used to obtain the hexagonal and the perovskite RMnO3 (R=Y,Ho,Er,Tm,Yb,Lu) compounds. We have refined the crystal structure and characterized the compounds with measurements of magnetic susceptibility χ(T) and thermal conductivity κ(T) . The systematic change of κ(T) below TN found in all members of the hexagonal RMnO3 family shows that some spin-independent bond-length fluctuation plays an important role in the suppression of κ(T) below TN as well as in the paramagnetic phase. The responsible soft vibrational mode is identified. In contrast, the perovskite RMnO3 shows a phonon-like κ(T) below room temperature, but with an anomalously large critical scattering at TN . A phase diagram of transition temperatures versus the R3+ -ion radius for both hexagonal and perovskite phases is also given.

  11. Modified Heisenberg model for the zig-zag structure in multiferroic RMn2O5

    Science.gov (United States)

    Bahoosh, Safa Golrokh; Wesselinowa, Julia M.; Trimper, Steffen

    2015-08-01

    The class of RMn2O5 (R = Ho, Tb, Y, Eu) compounds offers multiferroic properties where the refined magnetic zig-zag order breaks the inversion symmetry. Varying the temperature, the system undergoes a magnetic and a subsequent ferroelectric phase transition where the ferroelectricity is magnetically induced. We propose a modified anisotropic Heisenberg model that can be used as a tractable analytical model studying the properties of those antiferromagnetic zig-zag spin chains. Based on a finite temperature Green's function method, it is shown that the polarization is induced solely by different exchange couplings of the two different Mn4+ and Mn3+ magnetic ions. We calculate the excitation energy of the spin system for finite temperatures, which for its part determines the temperature dependent magnetization and polarization. The ferroelectric phase transition is manifested as a kink in the excitation energy. The variation of the polarization by an external magnetic field depends strongly on the direction of that field. Whereas, the polarization in b-direction increases with an external magnetic field as well in b-direction it can be switched for strong fields in a-direction. The results based on that modified Heisenberg model are in qualitative agreement with experimental data.

  12. Local structure studies of multiferroic RMn2O5 (R=Bi, Pr, Gd)

    Science.gov (United States)

    Fabbris, G.; Massa, N. E.; Granado, E.; Maciel, G. A.; Souza, J. A.; Alonso, J. A.; Martinez, M. J.; Azevedo, G. M.

    2009-03-01

    EXAFS measurements from 20 K to 300K were used to investigate the local structure of multiferroic RMn2O5 (R = Bi, Pr, Gd, TM TC 40K) in transmission mode at the Mn K- and R L3- edges in the XAFS2-LNLS beamline and analyzed using the IFEFFIT and FEFF codes. For BiMn2O5, Mn K-edge reveals very small temperature dependence of the Debye-Waller factor (DWF) and an Einstein temperature (ET) from Mn-O bonds of 675±22 K, suggesting that MnO polyhedra are rigid. We find structural distortions in the first coordination shell at the Bi L3-edge associated to vibrational anomalies in the Bi-O bonds. The quantitative analysis relates the origin of such distortions to two very distinct values of DWT and ET (294±7K and 462±28K) for these bonds on first shell. Similar behavior is observed for PrMn2O5, and GdMn2O5.

  13. Pressure effect on ferroelectric properties of multiferroics RMn2O5, (R = Gd, Tm)

    Science.gov (United States)

    Poudel, Narayan; Gooch, Melissa; Lorenz, Bernd; Chu, Ching-Wu; Kim, Jaewook; Cheong, Sang-Wook

    The pressure effect on the ferroelectric properties of the multiferroics GdMn2O5 and TmMn2O5 is studied up to 18.2 kbar. Unlike in RMn2O5 (R= Tb, Ho, Y), no significant change in polarization is observed in TmMn2O5 up to 16.6 kbar . However, a new ferroelectric phase is observed in GdMn2O5 above a critical pressure, Pc = 10 kbar at higher temperature. Our result indicates that pressure decouples the Gd moment from the Mn spin system and splits the ferroelectric phase. Thermal expansion data shows a large increase of the c axis at the ambient-pressure ferroelectric transition. The pressure-induced contraction of the c lattice parameter is found to be the cause for splitting of ferroelectric phase by decoupling of two spin systems above Pc. The pressure-temperature phase diagram is derived based on dielectric and ferroelectric properties.

  14. Magnetic behavior of RMn2+xAl10-x (R=La,Gd) crystals

    Science.gov (United States)

    Sefat, Athena S.; Li, Bin; Bud'Ko, Sergey L.; Canfield, Paul C.

    2007-11-01

    The crystallographic and magnetic properties of the solution grown RMn2+xAl10-x ( R=Gd and La) crystals with tetragonal (P4/nmm) structure are investigated. For these, single-crystal x-ray diffraction results have shown the preferential occupation of excess manganese on the aluminum 8i crystallographic site. Due to excess Mn, there is evidence of local-moment magnetism in LaMn2+xAl10-x and their random distribution is thought to be responsible for the magnetic correlations below ˜50K and the spin-glass behavior below ˜3K . For GdMn2+xAl10-x , the extra manganese influences temperature below which the sample enters into a state with a net ferromagnetic component: TC≈16K for GdMn2.21(4)Al9.79(4) and 25.5K for GdMn2.39(2)Al9.61(2) . Assuming a linear dependence between TC and excess Mn concentration, the fully stoichiometric and ordered GdMn2Al10 should have TC≈5K .

  15. Pressure dependent structural changes and predicted electrical polarization in perovskite RMnO₃.

    Science.gov (United States)

    Wu, T; Chen, H; Gao, P; Yu, T; Chen, Z; Liu, Z; Ahn, K H; Wang, X; Cheong, S-W; Tyson, T A

    2016-02-10

    High pressure x-ray diffraction measurements on perovskite RMnO3 (R  =  Dy, Ho and Lu) reveal that varying structural changes occur for different R ions. Large lattice changes (orthorhombic strain) occur in DyMnO3 and HoMnO3 while the Jahn-Teller (JT) distortion remains stable. Conversely, in the small R-ion system LuMnO3, Mn-O bond distortions are observed between 4 and 8 GPa with a broad minimum in the JT distortion. High pressure infrared measurements indicate that a phonon near 390 cm(-1) corresponding to the complex motion of the Mn and O ions changes anomalously for LuMnO3. It softens in the 4-8 GPa region, which is consistent with the structural change in Mn-O bonds and then hardens at higher pressures. By contrast, the phonons continuously harden with increasing pressure for DyMnO3 and HoMnO3. Density functional theory methods show that E-phase LuMnO3 is the most stable phase up to the 10 GPa pressure examined. Simulations indicate that the distinct structural change under pressure in LuMnO3 can possibly be used to optimize the electric polarization by pressure/strain.

  16. Pressure dependent structural changes and predicted electrical polarization in perovskite RMnO3

    Science.gov (United States)

    Wu, T.; Chen, H.; Gao, P.; Yu, T.; Chen, Z.; Liu, Z.; Ahn, K. H.; Wang, X.; Cheong, S.-W.; Tyson, T. A.

    2016-02-01

    High pressure x-ray diffraction measurements on perovskite RMnO3 (R  =  Dy, Ho and Lu) reveal that varying structural changes occur for different R ions. Large lattice changes (orthorhombic strain) occur in DyMnO3 and HoMnO3 while the Jahn-Teller (JT) distortion remains stable. Conversely, in the small R-ion system LuMnO3, Mn-O bond distortions are observed between 4 and 8 GPa with a broad minimum in the JT distortion. High pressure infrared measurements indicate that a phonon near 390 cm-1 corresponding to the complex motion of the Mn and O ions changes anomalously for LuMnO3. It softens in the 4-8 GPa region, which is consistent with the structural change in Mn-O bonds and then hardens at higher pressures. By contrast, the phonons continuously harden with increasing pressure for DyMnO3 and HoMnO3. Density functional theory methods show that E-phase LuMnO3 is the most stable phase up to the 10 GPa pressure examined. Simulations indicate that the distinct structural change under pressure in LuMnO3 can possibly be used to optimize the electric polarization by pressure/strain.

  17. Jahn-Teller distortion and magnetic transitions in perovskite RMnO3 ( R=Ho , Er, Tm, Yb, and Lu)

    Science.gov (United States)

    Tachibana, Makoto; Shimoyama, Tomotaka; Kawaji, Hitoshi; Atake, Tooru; Takayama-Muromachi, Eiji

    2007-04-01

    The perovskite RMnO3 ( R=Ho , Er, Tm, Yb, and Lu) were prepared under high pressure and studied with heat capacity and synchrotron x-ray powder diffraction measurements. The temperature interval between the antiferromagnetic transition and the first-order transition to the presumably E -type structure narrows with the decreasing ionic radius of R , and almost closes for R=Lu . Combined with the data for the larger rare earth R , the results show intricate relationship between the complex magnetic phase diagram and significant increase of Jahn-Teller distortion found for the smallest members of RMnO3 .

  18. High-pressure structural stability of multiferroic hexagonal RMnO3 (R=Y, Ho, Lu)

    Science.gov (United States)

    Gao, P.; Chen, Z.; Tyson, T. A.; Wu, T.; Ahn, K. H.; Liu, Z.; Tappero, R.; Kim, S. B.; Cheong, S.-W.

    2011-06-01

    Structural changes in RMnO3 (R= Y, Ho, Lu) under high pressure were examined by synchrotron x-ray diffraction methods at room temperature. Compression occurs more readily in the ab plane than along the c axis. With increased pressure, a pressure-induced hexagonal to orthorhombic phase transition was observed starting at ˜22 GPa for Lu(Y)MnO3. When the pressure is increased to 35 GPa, a small volume fraction of Lu(Y)MnO3 is converted to the orthorhombic phase and the orthorhombic phase is maintained on pressure release. High-pressure infrared absorption spectroscopy and Mn K-edge near-edge x-ray absorption spectroscopy confirm that the hexagonal P63cm structure is stable below ˜20 GPa and the environment around the Mn ion is not changed. Shifts in the unoccupied p-band density of states with pressure are observed in the Mn K-edge spectra. A schematic pressure-temperature phase diagram is given for the small ion RMnO3 system.

  19. High-pressure structural stability of multiferroic hexagonal RMnO3 (R=Y, Ho, Lu)

    Energy Technology Data Exchange (ETDEWEB)

    Gao, P.; Tappero, R.; Chen, Z.; Tyson, T.A.; Wu, T.; Ahn, K.H.; Liu, Z.; Kim, S.B. and Cheong, S.W.

    2011-06-27

    Structural changes in RMnO{sub 3} (R= Y, Ho, Lu) under high pressure were examined by synchrotron x-ray diffraction methods at room temperature. Compression occurs more readily in the ab plane than along the c axis. With increased pressure, a pressure-induced hexagonal to orthorhombic phase transition was observed starting at {approx}22 GPa for Lu(Y)MnO{sub 3}. When the pressure is increased to 35 GPa, a small volume fraction of Lu(Y)MnO{sub 3} is converted to the orthorhombic phase and the orthorhombic phase is maintained on pressure release. High-pressure infrared absorption spectroscopy and Mn K-edge near-edge x-ray absorption spectroscopy confirm that the hexagonal P6{sub 3}cm structure is stable below {approx}20 GPa and the environment around the Mn ion is not changed. Shifts in the unoccupied p-band density of states with pressure are observed in the Mn K-edge spectra. A schematic pressure-temperature phase diagram is given for the small ion RMnO{sub 3} system.

  20. High-pressure Structural Stability of Multiferroic Hexagonal RMnO3 (R=Y Ho Lu)

    Energy Technology Data Exchange (ETDEWEB)

    P Gao; Z Chen; T Tyson; T Wu; K Ahn; Z Liu; R Tappero; S Kim; S Cheong

    2011-12-31

    Structural changes in RMnO{sub 3} (R = Y, Ho, Lu) under high pressure were examined by synchrotron x-ray diffraction methods at room temperature. Compression occurs more readily in the ab plane than along the c axis. With increased pressure, a pressure-induced hexagonal to orthorhombic phase transition was observed starting at {approx}22 GPa for Lu(Y)MnO{sub 3}. When the pressure is increased to 35 GPa, a small volume fraction of Lu(Y)MnO{sub 3} is converted to the orthorhombic phase and the orthorhombic phase is maintained on pressure release. High-pressure infrared absorption spectroscopy and Mn K-edge near-edge x-ray absorption spectroscopy confirm that the hexagonal P6{sub 3}cm structure is stable below {approx}20 GPa and the environment around the Mn ion is not changed. Shifts in the unoccupied p-band density of states with pressure are observed in the Mn K-edge spectra. A schematic pressure-temperature phase diagram is given for the small ion RMnO{sub 3} system.

  1. Order Parameters and Phase Diagram of Multiferroic RMn2O5

    Science.gov (United States)

    Harris, A. Brooks

    2009-03-01

    ρ τ λ σ ξ χ 1 2 1 3 1 4 3 4 Recently there has been great interest in systems which display phase transitions at which incommensurate magnetic order and a spontaneous polarization develop simultaneously. Perhaps the most puzzling and seemingly complicated behavior occurs in the series of compounds RMn2O5, where R=Y, Ho, Er, Tb, Tm, and Dy. (For references to experimental data, see [1].) The sequence of magnetoelectric phases of the type I systems R=Tb, Ho, and Dy is slightly different from that of the type II systems R= Y, Tm, and Er. At about 45K both types develop essentially collinear modulated magnetic order into a ``high-temperature ordered" (HTO) phase with a wave vector q = (1/2-δ, 0, 1/4 + ɛ) where δ and |ɛ| are of order 0.01 and the spontaneous polarization is zero. There is a lower-temperature phase transition to a ferroelectric phase in which transverse magnetic order appears and produces a magnetic spiral with δ=ɛ=0. In type I systems, this transition occurs directly from the HTO phase, whereas for type II systems, there is an intervening ferroelectric phase in which ɛ=0, but δ remains nonzero. %At low (<10K) temperature the classification into types I and II %breaks down and each system requires its own specific description. I will discuss a Landau free energy[1] which allows both type I and type II sequences of phase transitions. This theory is couched in terms of the uniform polarization vector P and two complex-valued magnetic order parameters σ1(q) and σ2(q) whose symmetry follows from the magnetic structure analyses.[2] The magnetoelectric coupling and the competition between commensurate and incommensurate phases are analyzed. [4pt] [1] A. B. Harris, A. Aharony, and O. Entin-Wohlman, Phys. Rev. Lett. 100, 217202 (2008) and J. Phys. Condens. Mat. 20, 434202 (2008). [0pt] [2] A. B. Harris, Phys. Rev. 76, 054447 (2007); A. B. Harris, M. Kenzelmann, A. Aharony, and O. Entin-Wohlman, Phys. Rev. B 78, 014407 (2008).

  2. Development of applications in Internet for the calculation of solar control devices; Desarrollo de una aplicacion en Internet para el calculo de dispositivos de control solar

    Energy Technology Data Exchange (ETDEWEB)

    Perez V, Jesus B; Robles G, Saul; Villa M, Hector A; Cabanillas L, Rafael E [Universidad de Sonora, Hermosillo, Sonora (Mexico)

    2000-07-01

    In this work the development of an interactive software, visible over the World Wide Web, is presented to support the basic calculation required to control the solar gain inside buildings and houses. The site has two main parts: one part describes in a very required parameters to design devices for the control of the illumination inside the buildings, like overhangs and wingwalls for shading. The other part has the routines and procedures to calculate the sun position for any date and position over the earth, and the horizontal and vertical protection angles. The part to implement the calculations has been developed as a Java applet which can run on any platform and let the users, in an interactive way, to get the results. This software makes possible that any Internet user can run the application from his/her own computer without having to compile of use sophisticated procedures as it happens with traditional languages. With this web site it is intended to cover the necessity of having simple and reliable means for architects and civil engineers to support the use of solar energy and the saving of energy in bioclimatic design of buildings. [Spanish] En este trabajo se presenta el desarrollo de un sitio interactivo visible en el World Wide Web (WWW) que pretende servir de apoyo para los calculos basicos de control de asoleamiento en viviendas y edificios. El sitio esta conformado por dos partes principales: una parte cubre el aspecto informativo, donde en forma sencilla y clara, se explican los conceptos y parametros necesarios para disenar los dispositivos de control, alerones y parteluces. La otra parte contiene los procedimientos y las rutinas de calculo para la determinacion de la posicion solar para cualquier fecha del ano desde cualquier punto sobre la tierra, asi como los angulos de sombreado vertical y horizontal. Para la realizacion de los calculos se ha construido un applet de Java, el cual puede ejecutarse desde cualquier plataforma de computacion y

  3. Data acquisition system and calculation for the evaluation of polluting emissions in stacks; Sistema de adquisicion de datos y calculo para la evaluacion de emisiones contaminantes en chimeneas

    Energy Technology Data Exchange (ETDEWEB)

    Leon Enriquez, Javier

    1999-06-01

    The present thesis work, was developed in Visual C++5, to replace the present procedure of calculation in Excel and to avoid the manual processing of the data obtained during the evaluation of polluting from stacks, with movable laboratories that make dilutions in the originating gaseous sample of the stack. Six projects in Visual C++5 were designed. The first five include the formulas and procedures of calculation to obtain the total particulate emission suspended originating of stationary sources (stacks), indicated in the Code of Federal Regulations (CFR) part 60, emitted by the Environmental Protection Agency of the United Sates (EPA). The last one, includes the calculations necessary to read archives generated by a card of data acquisition and to consider the factor of dilution of the gaseous sample. A standard business card for the data acquisition is used during the monitoring process of the variables that requires the sixth mentioned project previously. The results of the monitoring of variables and result of the calculations are stored in archives that conform a data base of the made work, which allows future, to compare the results of the measurements and calculations in different evaluations from a same user. The made work can be used by evaluators companies of polluting emissions in stacks that count on dilution equipment during the evaluation. [Spanish] El presente trabajo de tesis, fue desarrollado en visual C++5, para sustituir el procedimiento actual de calculo en Excel y evitar el procesamiento manual de los datos obtenidos durante la evaluacion de emisiones contaminantes en chimeneas, con laboratorios moviles que realizan diluciones en la muestra gaseosa proveniente de la chimenea. Se disenaron 6 proyectos en visual C++5. Los primeros cinco incluyen las formulas y procedimientos de calculo para obtener la emision de particulas suspendidas totales provenientes de fuentes fijas (chimeneas), indicadores en el Codigo de Regulaciones Federales (CFR

  4. Magnetically frustrated behavior in multiferroics RMn2O5 (R =Bi, Eu, and Dy): A Raman scattering study

    Science.gov (United States)

    García-Flores, A. F.; Granado, E.; Martinho, H.; Rettori, C.; Golovenchits, E. I.; Sanina, V. A.; Oseroff, S. B.; Park, S.; Cheong, S.-W.

    2007-05-01

    A temperature dependent Raman scattering study in multiferroic single crystals RMn2O5 (R =Bi, Eu, and Dy) was performed. The Raman spectra were measured in the range from 150to450cm-1 involving mostly Mn-O-Mn bending vibrations, complementing our previous work in a higher frequency range involving Mn-O stretching modes. A number of studied phonons present anomalous frequency behavior below a characteristic temperature, T*˜60-65K, such as that found for the stretching modes. The sign and magnitude of such anomalous behavior appear to be correlated with the ionic radius of R, being softening for R =Bi and hardening for R =Eu and Dy in the range between TC/TN and T*. The anomalous phonon behaviors in both bending and stretching modes are consistent with an interpretation in terms of the spin-phonon coupling in a scenario of strong magnetic correlations.

  5. Role of the apical oxygen in RMnO3 (R = Ho and Lu) low temperature magneto-electric effect

    Science.gov (United States)

    Vermette, Jonathan; Jandl, Serge

    2012-02-01

    Multiferroic materials are promising candidates for new innovative devices, particularly in the field of memory storage. The strong coupling between magnetic ordering and ferroelectricity characterizing these compounds allows the modulation of the electric polarization (magnetic moment) with an external magnetic (electric) field. Hexagonal RMnO3 (Ho to Lu) compounds are type-I multiferroics in which ferroelectricity and magnetism have different sources giving a relative weak magneto-electric coupling with a large polarization. In this case ferroelectricity is induced at a relative high temperature (TC ˜ 800K) following a structural transition, while magnetic ordering of Mn^3+ and R^3+ occurs at lower temperatures (T LuMnO3 under applied magnetic field below THo = 5K. By comparing the renormalized force constants and the Born-effective charges, apical oxygen role in Ho^3+-Mn^3+ superexchange interaction is particularly underlined.

  6. Análisis de biodiesel preparado a partir de residuos de aceite doméstico, mediante RMN.

    OpenAIRE

    Cedron, Torres, Juan Carlos; Universidad de Ingeniería y Tecnología - UTEC; Perú

    2014-01-01

    Publicado en Revista Sociedad Química del Perú el 14/02/2014 Se preparó biodiesel a partir de residuos de aceite doméstico, mediante la reacción de transesterificación usando etanol. El rendimiento de la reacción fue del 78%, y el producto obtenido fue caracterizado por sus propiedades fisicoquímicas. Un análisis detallado del espectro de 1H-RMN permitió calcular que la conversión de triglicéridos en ésteres monoalquilados fue del 98,82%, lo cual indica que el biodiesel tiene la calidad re...

  7. Estudio teorico de las interacciones de dos modelos de ácidos húmicos con los cationes Al3+, Ca2+, Mg2+, Zn2+, K+ y NH4+ a un nivel de calculo DFT y un modelo de solvatación PCM

    Directory of Open Access Journals (Sweden)

    Eduardo Espinosa-Fuentes

    Full Text Available In this paper, two models of humic acids, the Temple-Northeastern-Birmingham (TNB and Kolla models, were studied. Also, the complexation reaction of the structures formed by the interaction of the TNB and Kolla models with Al3+, Ca2+, Mg2+, Zn2+, K+ and NH4+ cations, common in agricultural soils, was studied. These calculations were made for the complexes, at PM6 and DFT / LANL2DZ level of theory, both in vacuum and in aqueous medium. We found a strong affinity between Kolla and TNB models, and Al3+, Ca2+, Mg2+, Zn2+, K+ and NH4+ cations, influenced by the solvent that affected the interaction sites; the solvent increased the rate of reactivity and affinity for the cations in nucleophilic regions and decreased it in electrophilic regions of the structures. Calculations of molecular electronic potential, MEP and atomic charges, the local smoothness, Fukui functions and the HSAB principle adequately described the HA/cations interactions which were affected by the number of hydrogen bonds. The most reactive sites were the hydroxyl, phenolic, carbonyls oxygens and nitrogens at both vacuum and aqueous medium, especially carbonyl oxygens. These results are consistent with the properties of HA that make them attractive as components of agricultural soils.

  8. Neutron diffraction study of the La1-xPrxMn2Si2 ( x=0.4, 0.7 and 1) compounds and the general description of the magnetic behavior of Mn in RMn2Ge2 and RMn2Si2

    Science.gov (United States)

    Dincer, I.; Elerman, Y.; Elmali, A.; Ehrenberg, H.; André, G.

    2007-06-01

    The magnetic structures of the La1-xPrxMn2Si2 ( x=0.4, 0.7 and 1) have been investigated by powder neutron diffraction between 2 and 308 K. According to magnetic measurements, the x=0.4 sample shows a typical SmMn2Ge2-like magnetic behavior. Neutron diffraction indicates a canted antiferromagnetic structure below 130 K and a canted ferromagnetic structure above 240 K. Between 130 and 240 K, the canted ferromagnetic and antiferromagnetic structures coexist. Since the magnetic moments of Mn atoms, the unit cell parameters and the scale parameters of the canted antiferromagnetism and canted ferromagnetism are highly correlated between 130 and 240 K, a special refinement procedure was introduced. The critical Mn-Mn value was determined as 2.87 A˚, and the spontaneous volume change and linear magnetostriction are derived. Neutron diffraction revealed a canted antiferromagnetic structure for La0.3Pr0.7Mn2Si2. A canted antiferromagnetic structure was also detected for PrMn2Si2 by neutron diffraction in contrast to previous reports of a collinear arrangement. The present results are compiled together with previous ones on RMn2Ge2 and RMn2Si2 (R: Y, La and rare-earth) compounds in two magnetic phase diagrams. These two graphics summarize the general magnetic behavior of Mn in the RMn2Ge2 and RMn2Si2 compounds.

  9. Hydrothermal synthesis and magnetic properties of RMn 2O 5 ( R=La, Pr, Nd, Tb, Bi) and LaMn 2O 5+δ

    Science.gov (United States)

    Chen, Yan; Yuan, Hongming; Tian, Ge; Zhang, Ganghua; Feng, Shouhua

    2007-04-01

    RMn 2O 5 ( R=La, Pr, Nd, Tb, Bi) crystallites were prepared by a mild hydrothermal method and characterized by powder X-ray diffraction, scanning electron microscopy, X-ray photoelectron spectroscopy (XPS) and magnetic measurement. The formation of manganates was sensitive to the alkalinities and Mn-containing precursors of the reaction mixtures. This family of manganates is isostructural and has a space group of Pbam. The magnetic measurements for RMn 2O 5 showed an antiferromagnetic transition. The strong irreversibility between the ZFC and FC curves indicated a helicoidally magnetic structure below 40 K. The max d.c. susceptibilities of LaMn 2O 5+δ ( δ=0.01, 0.06, 0.08, 0.16, 0.17) were found to be variable and the excess oxygen ( δ) in the compounds was influenced by the alkalinity used in the hydrothermal synthesis.

  10. Magnetic transition from the paramagnetic to long-period structure in RMn2O5 multiferroics: Renormalization group analysis of critical behavior

    Science.gov (United States)

    Men'shenin, V. V.

    2013-06-01

    A transition from the paramagnetic state to a long-period magnetic structure with an incommensurate wave vector along one crystallographic axis in RMn2O5 multiferroics is considered. An effective Hamiltonian for these oxides is constructed with allowance for spin fluctuations. Critical points are found, and their stability is analyzed using the renormalization group approach. It is shown that critical fluctuations in these compounds admit a second-order phase transition with respect to a multicomponent order parameter.

  11. Electric polarization induced by phase separation in magnetically ordered and paramagnetic states of RMn2O5 (R=Gd, Bi)

    Science.gov (United States)

    Khannanov, B. Kh.; Sanina, V. A.; Golovenchits, E. I.; Scheglov, M. P.

    2017-01-01

    The electric polarization hysteresis loops and remanent polarization were revealed in multiferroics RMn2O5 with R=Gd and Bi at wide temperature interval from 5 K up to 330 K. Until recently, the long-range ferroelectric order having an exchange-striction magnetic nature had been observed in RMn2O5 only at low temperatures (T ≤TC = 30 - 35 K) . We believe that the polarization we observed was caused by the frozen superparaelectric state which was formed by the restricted polar domains resulting from phase separation and charge carriers self-organization. At some sufficiently high temperatures T ≫TC the frozen superparaelectric state was destroyed, and the conventional superparaelectric state occurred. This happened when the potential barriers of the restricted polar domain reorientations become equal to the kinetic energy of the itinerant electrons (leakage). The hysteresis loops were measured by the so-called PUND method which allowed us to correctly subtract the contribution of conductivity from the measured polarization. The correlations between properties of the phase separation domains and polarization were revealed and studied. The high-temperature polarization also had a magnetic nature and was controlled by the magnetic field because the double exchange between pairs of Mn ions with different valences (Mn3+ and Mn4+) in RMn2O5 was the basic interaction resulting in phase separation.

  12. Commensurate magnetic structures of RMn2O5 (R=Y,Ho,Bi) determined by single-crystal neutron diffraction

    Science.gov (United States)

    Vecchini, C.; Chapon, L. C.; Brown, P. J.; Chatterji, T.; Park, S.; Cheong, S.-W.; Radaelli, P. G.

    2008-04-01

    Precise magnetic structures of RMn2O5 , with R=Y,Ho,Bi in the commensurate and/or ferroelectric regime, have been determined by single-crystal neutron diffraction. For each system, the integrated intensities of a large number of independent magnetic Bragg reflections have been measured, allowing unconstrained least-squares refinement of the structures. The analysis confirms the previously reported magnetic configuration in the ab plane, in particular, the existence of zigzag antiferromagnetic chains. For the Y and Ho compounds, additional weak magnetic components parallel to the c axis were detected, which are modulated in phase quadrature with the a-b components. This component is extremely small in the BiMn2O5 sample, therefore supporting symmetric exchange as the principal mechanism inducing ferroelectricity. For HoMn2O5 , a magnetic ordering of the Ho moments was observed, which is consistent with a superexchange interaction through the oxygens. For all three compounds, the point symmetry in the magnetically ordered state is m2m , allowing the polar b axis found experimentally.

  13. Pressure-induced changes in the magnetic and magnetocaloric properties of RMn2Ge2 (R=Sm,Gd)

    Science.gov (United States)

    Kumar, Pramod; Suresh, K. G.; Nigam, A. K.; Magnus, A.; Coelho, A. A.; Gama, S.

    2008-06-01

    We have studied the variation of magnetic and magnetocaloric properties of polycrystalline compounds SmMn2Ge2 and GdMn2Ge2 as a function of applied hydrostatic pressure. The magnetic transition temperatures are found to change considerably with pressure. The temperature regime of existence of antiferromagnetic (AFM) ordering is found to increase with pressure, in both the compounds. In SmMn2Ge2 , the sign of the magnetocaloric effect at the low-temperature ferromagnetic (FM)-AFM transition changes with pressure. The isothermal magnetic entropy change in this compound is found to increase by about 20 times as the pressure is increased from the ambient value to 6.8 kbar. Effect of pressure in GdMn2Ge2 is less compared to that in SmMn2Ge2 . The variations in the magnetic and magnetocaloric properties are attributed to the changes in the magnetic state of the Mn sublattice under pressure. The difference in R-Mn coupling in Sm and Gd compounds is also found to play a role in determining the magnetic and magnetocaloric properties, both at ambient as well as under applied pressures.

  14. Pressure-induced enhancement of ferroelectricity in multiferroic RMn2O5 (R=Tb,Dy,Ho)

    Science.gov (United States)

    Dela Cruz, C. R.; Lorenz, B.; Sun, Y. Y.; Wang, Y.; Park, S.; Cheong, S.-W.; Gospodinov, M. M.; Chu, C. W.

    2007-11-01

    Measurements of ferroelectric polarization and dielectric constant were done on RMn2O5 (R=Tb,Dy,Ho) with applied hydrostatic pressures of up to 18kbar . At ambient pressure, distinctive anomalies were observed in the temperature profile of both physical properties at critical temperatures marking the onset of long range antiferromegnetic order (TN1) and ferroelectricity (TC1) , as well as at temperatures when anomalous changes in the polarization, dielectric constant, and spin wave commensurability have been previously reported. In particular, the step in the dielectric constant at low temperatures (TC2) , associated with both a drop in the ferroelectric polarization and an incommensurate magnetic structure, was shown to be suddenly quenched upon passing an R -dependent critical pressure. This was shown to correlate with the stabilization of the high ferroelectric polarization state, which is coincident with the commensurate magnetic structure. The observation is suggested to be due to a pressure-induced phase transition into a commensurate magnetic structure, as exemplified by the pressure-temperature (p-T) phase diagrams constructed in this work. The p-T phase diagrams are determined for all three compounds.

  15. Magnetic phase transition and the corresponding magnetostriction of intermetallic compounds RMn2Ge2 (R=Sm, Gd)

    Institute of Scientific and Technical Information of China (English)

    Guo Guang-Hua(郭光华); Wu Ye(吴烨); Zhang Hai-Bei(张海贝); D A Filippov; R Z Levitin; V V Snegirev

    2002-01-01

    The temperature dependence of lattice constants a and c of intermetallic compounds RMn2Ge2 (R=Sm, Gd) is measured in the temperature range 10-800K by using the x-ray diffraction method. The magnetoelastic anomalies of lattice constants are found at the different kinds of spontaneous magnetic transitions. The transversal and longitudinal magnetostrictions of polycrystalline samples are measured in the pulse magnetic field up to 25T. In the external magnetic field there occurs a first-order field-induced antiferromagnetism-ferromagnetism transition in the Mn sublattice, which gives rise to a large magnetostriction. The magnitude of magnetostrictions is as large as 10-3. The transversal and longitudinal magnetostrictions have the same sign and are almost equal. This indicates that the magnetostriction is isotropic and mainly caused by the interlayer Mn-Mn exchange interaction. The experimental results are explained in the framework of a two-sublattice ferrimagnet with the negative exchange interaction in one of the sublattices by taking into account the lattice constant dependence of interlayer Mn-Mn exchange interaction.

  16. Modified Heisenberg model for the zig-zag structure in multiferroic RMn{sub 2}O{sub 5}

    Energy Technology Data Exchange (ETDEWEB)

    Bahoosh, Safa Golrokh, E-mail: safa.bahoosh@uni-konstanz.de [Department of Physics, University of Konstanz, D-78457 Konstanz (Germany); Wesselinowa, Julia M., E-mail: julia@phys.uni-sofia.bg [Department of Physics, University of Sofia, 1164 Sofia (Bulgaria); Trimper, Steffen, E-mail: steffen.trimper@physik.uni-halle.de [Institute of Physics, Martin-Luther-University Halle-Wittenberg, D-06099 Halle (Germany)

    2015-08-28

    The class of RMn{sub 2}O{sub 5} (R = Ho, Tb, Y, Eu) compounds offers multiferroic properties where the refined magnetic zig-zag order breaks the inversion symmetry. Varying the temperature, the system undergoes a magnetic and a subsequent ferroelectric phase transition where the ferroelectricity is magnetically induced. We propose a modified anisotropic Heisenberg model that can be used as a tractable analytical model studying the properties of those antiferromagnetic zig-zag spin chains. Based on a finite temperature Green's function method, it is shown that the polarization is induced solely by different exchange couplings of the two different Mn{sup 4+} and Mn{sup 3+} magnetic ions. We calculate the excitation energy of the spin system for finite temperatures, which for its part determines the temperature dependent magnetization and polarization. The ferroelectric phase transition is manifested as a kink in the excitation energy. The variation of the polarization by an external magnetic field depends strongly on the direction of that field. Whereas, the polarization in b-direction increases with an external magnetic field as well in b-direction it can be switched for strong fields in a-direction. The results based on that modified Heisenberg model are in qualitative agreement with experimental data.

  17. Les écoulements par RMN à gradient pulsé Pulsed Gradient Nmr Techniques for Studying Flows

    Directory of Open Access Journals (Sweden)

    Lebon L.

    2006-12-01

    Full Text Available Nous présentons ici les techniques de RMN à gradient pulsé qui permettent d'étudier les écoulements multiphasiques en canalisation ou en milieu poreux. Les principaux avantages sont de pouvoir travailler sur des milieux non transparents et d'accéder à des échelles de longueurs faibles. On montre qu'il est possible d'obtenir des informations locales sur l'écoulement, telles que le profil de vitesse et ses fluctuations dans les écoulements diphasiques, ou les cartes de distribution des probabilités de déplacement dans des échantillons poreux hétérogènes. Pulsed gradient NMR techniques are presented here. They allow the study of multiphase flow in pipes as well as porous media. The main advantages are the possibilities of studying non transparent media at small length scales. We show that it is possible to obtain local information on the fluid flow, such as velocity profiles in two phase systems, or maps of distribution of displacement probabilities in heterogeneous porous media.

  18. Measurement and calculation of dynamic coefficients in hydrodynamic bearings of gas films; Medicion y calculo de coeficientes dinamicos en cojinetes hidrodinamicos de peliculas de gas

    Energy Technology Data Exchange (ETDEWEB)

    Ruiz, Rafael O.; Di Liscia, Marcelo H.; Diaz, Sergio E. [Universidad Simon Bolivar, Sartendejas, Baruta (Venezuela)

    2007-11-15

    dynamic coefficients. [Spanish] La identificacion de los coeficientes dinamicos en cojinetes de aire es fundamental para un adecuado analisis rotodinamico. El presente trabajo muestra el desarrollo de un algoritmo que permite la obtencion directa de los coeficientes dinamicos en cojinetes hidrodinamicos de aire tanto de forma numerica como experimental. El banco de pruebas utilizado consta de dos cojinetes magneticos, los cuales soportan al rotor en sus extremos y a su vez funcionan como actuadores permitiendo inducir orbitas controladas en el rotor. El cojinete de prueba se encuentra ubicado entre los cojinetes magneticos. Las fuerzas dinamicas generadas en el cojinete de aire se registran a partir de tres celdas de carga. El algoritmo fue desarrollado en un codigo comercial de programacion grafica, a traves del cual se pueden colectar, controlar y procesar las senales. El comportamiento no lineal de este tipo de cojinetes dificulta el calculo de los coeficientes dinamicos, por esta razon el procesamiento de las senales en espacio frecuencial facilita de cierta manera su manejo. Por otra parte, el modelo numerico se comparo con los resultados experimentales obteniendo aproximaciones aceptables tanto en magnitud como en comportamiento. El calculo de los coeficientes dinamicos numericos se realizo resolviendo la ecuacion diferencial de Reynolds para un fluido compresible en el espesor de la pelicula de gas, tomando en consideracion el flujo masico del fluido que se introduce, asi como la perdida de presion que sufre el mismo al pasar a traves de los orificios de alimentacion. Los metodos numericos utilizados incluyen la resolucion de la ecuacion diferencial de Reynolds por diferencias finitas, el calculo del perfil de presiones realizando iteraciones sucesivas y el calculo de las fuerzas hidrodinamicas a traves de una integracion numerica de Simpson. Los coeficientes dinamicos numericos fueron hallados aplicando una tecnica de minimos cuadrados a las fuerzas hidrodinamicas

  19. Neutron diffraction study of the La{sub 1-x}Pr{sub x}Mn{sub 2}Si{sub 2} (x=0.4, 0.7 and 1) compounds and the general description of the magnetic behavior of Mn in RMn{sub 2}Ge{sub 2} and RMn{sub 2}Si{sub 2}

    Energy Technology Data Exchange (ETDEWEB)

    Dincer, I. [Department of Engineering Physics, Faculty of Engineering, Ankara University, 06100 Besevler-Ankara (Turkey)]. E-mail: idincer@eng.ankara.edu.tr; Elerman, Y. [Department of Engineering Physics, Faculty of Engineering, Ankara University, 06100 Besevler-Ankara (Turkey); Elmali, A. [Department of Engineering Physics, Faculty of Engineering, Ankara University, 06100 Besevler-Ankara (Turkey); Ehrenberg, H. [Institute for Materials Science, Darmstadt University of Technology, Petersenstrasse 23, D-64287 Darmstadt (Germany); Andre, G. [Laboratoire Leon Brillouin (CEA-CNRS), CEN-Saclay, 91191 Gif-Sur-Yvette (France)

    2007-06-15

    The magnetic structures of the La{sub 1-x}Pr{sub x}Mn{sub 2}Si{sub 2} (x=0.4, 0.7 and 1) have been investigated by powder neutron diffraction between 2 and 308K. According to magnetic measurements, the x=0.4 sample shows a typical SmMn{sub 2}Ge{sub 2}-like magnetic behavior. Neutron diffraction indicates a canted antiferromagnetic structure below 130K and a canted ferromagnetic structure above 240K. Between 130 and 240K, the canted ferromagnetic and antiferromagnetic structures coexist. Since the magnetic moments of Mn atoms, the unit cell parameters and the scale parameters of the canted antiferromagnetism and canted ferromagnetism are highly correlated between 130 and 240K, a special refinement procedure was introduced. The critical Mn-Mn value was determined as 2.87Angst, and the spontaneous volume change and linear magnetostriction are derived. Neutron diffraction revealed a canted antiferromagnetic structure for La{sub 0.3}Pr{sub 0.7}Mn{sub 2}Si{sub 2}. A canted antiferromagnetic structure was also detected for PrMn{sub 2}Si{sub 2} by neutron diffraction in contrast to previous reports of a collinear arrangement. The present results are compiled together with previous ones on RMn{sub 2}Ge{sub 2} and RMn{sub 2}Si{sub 2} (R: Y, La and rare-earth) compounds in two magnetic phase diagrams. These two graphics summarize the general magnetic behavior of Mn in the RMn{sub 2}Ge{sub 2} and RMn{sub 2}Si{sub 2} compounds.

  20. Structural and magnetic properties of RMn 2- xFe xD 6 compounds ( R=Y, Er; x≤0.2) synthesized under high deuterium pressure

    Science.gov (United States)

    Paul-Boncour, V.; Filipek, S. M.; Sato, R.; Wierzbicki, R.; André, G.; Porcher, F.; Reissner, M.; Wiesinger, G.

    2011-02-01

    RMn 2- xFe xD 6 compounds were obtained by applying a deuterium pressure of several kbar to RMn 2- xFe x compounds for x≤0.2 and R=Y, Er. These compounds are isostructural to RMn 2D 6 compounds and crystallize in a K 2PtCl 6 type structure with a random substitution of R and half the Mn atoms in the same 8c site whereas the other Mn atoms are located on the 4a site and surrounded by six D atoms (24e site). According to neutron powder diffraction analysis the Fe atoms are preferentially substituted on the 4a site. YMn 2- xFe xD 6 compounds are paramagnetic and their molar susceptibility follows a modified Curie-Weiss law. ErMn 2- xFe xD 6 compounds display a ferromagnetic behavior at 2 K, but their saturation magnetization ( MS˜4.0 μ B/f.u.) is half that of their parent compounds ( MS˜8.0 μ B/f.u.). The neutron diffraction patterns of ErMn 1.8Fe 0.2D 6 display below 13 K both ferromagnetic and antiferromagnetic short range order, which can be related to a disordered distribution of Er moments. The paramagnetic temperatures of ErMn 2- xFe xD 6 compounds are negative and decrease versus the Fe content whereas they are positive and increase for their parent compounds.

  1. Ab initio study of the structural, electronic, elastic and thermal properties of RMn{sub 2}Ge{sub 2} (R = Ca, Nd and Y) intermetallic compounds

    Energy Technology Data Exchange (ETDEWEB)

    Miloud Abid, O.; Yakoubi, A. [Laboratoire d’Etudes des Matériaux et Instrumentations Expérimentales, Université Djilali Liabes de Sidi Bel-Abbes, 22000 (Algeria); Tadjer, A. [Modeling and Simulation in Materials Science Laboratory, Physics Department, University of Sidi Bel-Abbes, Sidi Bel-Abbes (Algeria); Khenata, R., E-mail: khenata_rabah@yahoo.fr [Laboratoire de Physique Quantique de la Modélisation Mathématique (LPQ3M), Université de Mascara, 29000 (Algeria); Ahmed, R. [Department of Physics, Faculty of Science, Universiti Teknologi Malaysia, UTM Skudai, 81310 Johor (Malaysia); Murtaza, G. [Materials Modeling Laboratory, Department of Physics, Islamia College University, Peshawar (Pakistan); Bin Omran, S. [Department of Physics and Astronomy, College of Science, King Saud University, P.O. Box 2455, Riyadh 11451 (Saudi Arabia); Azam, Sikander [New Technologies – Research Center, University of West Bohemia, Univerzitni 8, 306 14 Pilsen (Czech Republic)

    2014-12-15

    Highlights: • The calculated structural parameters of RMn{sub 2}Ge{sub 2} (R = Ca, Nd and Y) compounds are found in good agreement with the experimental data. • The structural and band structure calculation reveals that these compounds are ferromagnetic brittle metals. • The elastic and thermodynamic properties for the herein studied compounds are investigated for the first time. - Abstract: Intermetallic RMn{sub 2}Ge{sub 2} ternary compounds have attracted considerable attention from researchers in recent years because they show strong indications for novel magnetic characteristics and they have the potential to reveal the mechanism of superlattices. The study of the paramagnetic, ferromagnetic and antiferromagnetic phases affirms the strong dependence to the distance between atomic species in these compounds. In this study, we investigated the structural, elastic, electronic and thermodynamic properties of the intermetallic RMn{sub 2}Ge{sub 2} (R = Ca, Nd and Y) compounds. To carry out this study, we used the full potential (FP) linearized (L) augmented plane wave plus local orbitals (APW + lo), a scheme of calculations developed within the frame work of density functional theory (DFT). To incorporate the exchange correlation (XC) energy and corresponding potential into the total energy calculations, local density approximation (LDA) parameterized by Perdew and Wang is taken into account. Analysis of the density of states (DOS) profile illustrates the conducting nature of these intermetallic compounds; with a predominantly contribution from the R and Mn-d states. At ambient conditions, calculations for elastic constants (C{sub 11}, C{sub 12}, C{sub 13}, C{sub 44}, C{sub 33} and C{sub 66}) are also performed, which point to their brittle character. In addition, the quasi harmonic Debye model was used to predict the thermal properties, together with relative expansion coefficients and heat capacity.

  2. Caracterização de nanocompósitos de poliuretano/montmorilonita organofílica por RMN de baixo campo

    Directory of Open Access Journals (Sweden)

    Marcos Anacleto da Silva

    Full Text Available Poliuretanos são materiais poliméricos importantes e versáteis, principalmente devido a algumas de suas propriedades, como alta resistência à abrasão, resistência ao rasgo, excelente absorção de choques mecânicos, boa flexibilidade e elasticidade. No entanto, existem também algumas desvantagens, como a baixa estabilidade térmica e propriedade de barreira. Para superar essas desvantagens, têm sido produzidos nanocompósitos de poliuretano/montmorilonita organofílica. A investigação da estrutura dos nanocompósitos de poliuretano/argila tem sido realizada principalmente por difração de raios X (DRX e microscopia eletrônica de transmissão (TEM. Neste trabalho, foram estudados filmes de nanocompósitos de PU/argila organofílica obtidos por intercalação por solução. Os nanocompósitos foram caracterizados por DRX e, principalmente, por ressonância magnética nuclear de baixo campo (RMN-BC. As medidas de RMN-BC, com a determinação do tempo de relaxação spin-rede do núcleo de hidrogênio, forneceram informações ímpares e importantes sobre a dinâmica molecular desses nanocompósitos. Para validar esse estudo foram realizadas análises de difração de raios X, que confirmaram os resultados de RMN. A estabilidade térmica dos materiais também foi determinada por análise termogravimétrica em atmosfera de gás inerte, observando-se pequena melhora na estabilidade do nanocompósito quando comparado com o poliuretano.

  3. Infrared-active excitations related to the R^3+ ligand-field splitting in RMn2O5 (R=Ho, Dy, Tb)

    Science.gov (United States)

    Sirenko, A. A.; O'Malley, S. M.; Kang, T. D.; Kahn, K. H.; Carr, C. L.; Mihaly, L.; Park, S.; Cheong, S.-W.

    2009-03-01

    Optical transitions between ligand-field split states of R^3+ ions in RMn2O5 multiferroic single crystals have been studied at the phase transitions in the external magnetic field up to 13 T and uniaxial pressure up to 5 kbar. Spectra of the ligand field excitations change significantly in external magnetic field and correlate with the reversal of electric polarization induced by magnetic field. The oscillator strength and selection rules for ligand field excitations change with external uniaxial pressure. We discuss the connection between the ligand field on R^3+ with the magnetism and dielectric properties of this compounds.

  4. Atribución inequívoca de las señales de RMN de un neolignano arilnaftalénico utilizando espectros bidimensionales

    Directory of Open Access Journals (Sweden)

    Juan C. Martínez V.

    2010-05-01

    Full Text Available La atribución sin ambigüedad de cada una de las señales de los espectros de RMN 1H y 13C del 2,3-dimetil-7-hidroxi-6-metoxi-1-(3', 4' - metilenodioxifenil naftaleno, fue realizada por medio de sus espectros bidimensionales de correlación homonuclear 1H-1H y de correlación heteronuclear 1C y 3H obtenido utilizando en la respectiva secuencia de pulsos tiempos de espera correspondientes

  5. Positive magnetoresistance and large magnetostriction at first-order antiferro ferromagnetic phase transitions in RMn2Si2 compounds

    Science.gov (United States)

    Gerasimov, E. G.; Mushnikov, N. V.; Koyama, K.; Kanomata, T.; Watanabe, K.

    2008-11-01

    The magnetostriction and magnetoresistance associated with the field-induced and spontaneous first-order antiferro-ferromagnetic (AF-F) phase transitions have been studied for quasi-single-crystalline samples of La0.25Sm0.75Mn2Si2, La0.25Y0.75Mn2Si2 and La0.27Y0.73Mn2Si2 compounds with natural layered ThCr2Si2-type structure. It was found that both the spontaneous and field-induced AF-F transitions are accompanied by a large volume magnetostriction ΔV/V≈2 × 10-3 and anisotropic linear changes of the lattice parameters Δa/a≈1.6 × 10-3, Δc/c≈-0.75 × 10-3. The field-induced AF-F magnetic phase transition has been observed in magnetic fields applied both along the c-axis and in the basal plane, and the magnetostriction value is virtually independent of the direction of applied field. It has been found also that the magnetoresistance is positive in these compounds (the value of the electrical resistance in the ferromagnetic state is higher than that in the antiferromagnetic state) for the fields applied both along the c-axis and in the basal plane. The value of the magnetoresistance observed along the c-axis is 30 times as high as that in the basal plane. The obtained results indicate that the electronic band structure changes are likely responsible for the AF-F magnetic phase transitions observed in the RMn2X2 compounds.

  6. Thermal stability of mullite RMn2O5 (R  =  Bi, Y, Pr, Sm or Gd): combined density functional theory and experimental study

    Science.gov (United States)

    Li, Chenzhe; Thampy, Sampreetha; Zheng, Yongping; Kweun, Joshua M.; Ren, Yixin; Chan, Julia Y.; Kim, Hanchul; Cho, Maenghyo; Kim, Yoon Young; Hsu, Julia W. P.; Cho, Kyeongjae

    2016-03-01

    Understanding and effectively predicting the thermal stability of ternary transition metal oxides with heavy elements using first principle simulations are vital for understanding performance of advanced materials. In this work, we have investigated the thermal stability of mullite RMn2O5 (R  =  Bi, Pr, Sm, or Gd) structures by constructing temperature phase diagrams using an efficient mixed generalized gradient approximation (GGA) and the GGA  +  U method. Simulation predicted stability regions without corrections on heavy elements show a 4-200 K underestimation compared to our experimental results. We have found the number of d/f electrons in the heavy elements shows a linear relationship with the prediction deviation. Further correction on the strongly correlated electrons in heavy elements could significantly reduce the prediction deviations. Our corrected simulation results demonstrate that further correction of R-site elements in RMn2O5 could effectively reduce the underestimation of the density functional theory-predicted decomposition temperature to within 30 K. Therefore, it could produce an accurate thermal stability prediction for complex ternary transition metal oxide compounds with heavy elements.

  7. Study of the Mn-Mn exchange interactions in single crystals of RMn{sub 6}Sn{sub 6} compounds with R = Sc, Y and Lu

    Energy Technology Data Exchange (ETDEWEB)

    Matsuo, A. [KYOKUGEN, Osaka University, Toyonaka, Osaka 560-8531 (Japan)]. E-mail: a-matsuo@issp.u-tokyo.ac.jp; Suga, K. [KYOKUGEN, Osaka University, Toyonaka, Osaka 560-8531 (Japan); Kindo, K. [KYOKUGEN, Osaka University, Toyonaka, Osaka 560-8531 (Japan); Zhang, L. [Van der Waals-Zeeman Instituut, Universiteit van Amsterdam, 1018 XE Amsterdam (Netherlands); Brueck, E. [Van der Waals-Zeeman Instituut, Universiteit van Amsterdam, 1018 XE Amsterdam (Netherlands); Buschow, K.H.J. [Van der Waals-Zeeman Instituut, Universiteit van Amsterdam, 1018 XE Amsterdam (Netherlands); Boer, F.R. de [KYOKUGEN, Osaka University, Toyonaka, Osaka 560-8531 (Japan); Van der Waals-Zeeman Instituut, Universiteit van Amsterdam, 1018 XE Amsterdam (Netherlands); Lefevre, C. [Lab. Chim. Sol. Mineral, Universite Henri Poincare-Nancy 1, 54506 Vandoeuvre les Nancy Cedex (France); Venturini, G. [Lab. Chim. Sol. Mineral, Universite Henri Poincare-Nancy 1, 54506 Vandoeuvre les Nancy Cedex (France)

    2006-02-09

    In order to investigate the behaviour of the magnetic anisotropy and the Mn-Mn exchange interaction in RMn{sub 6}Sn{sub 6} (R = rare earth) compounds, magnetic studies have been carried out on single crystals of RMn{sub 6}Sn{sub 6} compounds in which R is one of the non-magnetic elements Sc, Y and Lu. The temperature dependence of the magnetization of these compounds has been measured with the field applied parallel and perpendicular to the crystallographic c-direction. Magnetic isotherms of the three compounds were measured at 4.2 K in magnetic fields up to 50 T, applied parallel and perpendicular to the c-direction, sufficiently high to reach the forced ferromagnetic state and to detect multiple field-induced transitions. For LuMn{sub 6}Sn{sub 6}, magnetic isotherms were measured also at a higher temperature of 150 K. From our results we may conclude that the magnetic anisotropy as well as the antiferromagnetic coupling strength increases in the sequence of ScMn{sub 6}Sn{sub 6}, YMn{sub 6}Sn{sub 6} and LuMn{sub 6}Sn{sub 6}.

  8. Measurement and calculation of dynamic coefficients in hydrodynamic bearings of gas films; Medicion y calculo de coeficientes dinamicos en cojinetes hidrodinamicos de peliculas de gas

    Energy Technology Data Exchange (ETDEWEB)

    Ruiz, Rafael O.; Di Liscia, Marcelo H.; Diaz, Sergio E. [Universidad Simon Bolivar, Sartendejas, Baruta (Venezuela)

    2007-11-15

    dynamic coefficients. [Spanish] La identificacion de los coeficientes dinamicos en cojinetes de aire es fundamental para un adecuado analisis rotodinamico. El presente trabajo muestra el desarrollo de un algoritmo que permite la obtencion directa de los coeficientes dinamicos en cojinetes hidrodinamicos de aire tanto de forma numerica como experimental. El banco de pruebas utilizado consta de dos cojinetes magneticos, los cuales soportan al rotor en sus extremos y a su vez funcionan como actuadores permitiendo inducir orbitas controladas en el rotor. El cojinete de prueba se encuentra ubicado entre los cojinetes magneticos. Las fuerzas dinamicas generadas en el cojinete de aire se registran a partir de tres celdas de carga. El algoritmo fue desarrollado en un codigo comercial de programacion grafica, a traves del cual se pueden colectar, controlar y procesar las senales. El comportamiento no lineal de este tipo de cojinetes dificulta el calculo de los coeficientes dinamicos, por esta razon el procesamiento de las senales en espacio frecuencial facilita de cierta manera su manejo. Por otra parte, el modelo numerico se comparo con los resultados experimentales obteniendo aproximaciones aceptables tanto en magnitud como en comportamiento. El calculo de los coeficientes dinamicos numericos se realizo resolviendo la ecuacion diferencial de Reynolds para un fluido compresible en el espesor de la pelicula de gas, tomando en consideracion el flujo masico del fluido que se introduce, asi como la perdida de presion que sufre el mismo al pasar a traves de los orificios de alimentacion. Los metodos numericos utilizados incluyen la resolucion de la ecuacion diferencial de Reynolds por diferencias finitas, el calculo del perfil de presiones realizando iteraciones sucesivas y el calculo de las fuerzas hidrodinamicas a traves de una integracion numerica de Simpson. Los coeficientes dinamicos numericos fueron hallados aplicando una tecnica de minimos cuadrados a las fuerzas hidrodinamicas

  9. Anisotropic contributions to the Sn119 transferred hyperfine fields in RMn6Sn6-xXx ( R=Y,Tb,Er ; X=In,Ga )

    Science.gov (United States)

    Perry, Laura K.; Ryan, D. H.; Venturini, G.

    2007-04-01

    The anisotropic contribution to the transferred hyperfine fields in YMn6Sn5.42In0.58 has been isolated using a field-driven moment rotation from the ab plane to the c axis in a single crystal. We find that at 12K , the anisotropic contribution is between 3% and 4% of the total field for the Sn2c and Sn2d sites, while it accounts for nearly one-third of the observed field at the Sn2e site. Comparison with data from RMn6Sn6-xXx ( R=Tb,Er ; X=Ga,In ) compounds containing magnetic rare earths shows that the Mn and R contributions to the anisotropic component of the transferred hyperfine fields are similar in magnitude.

  10. Collective phase-like mode and the role of lattice distortions at TN ˜ TC in RMn2O5 (R= Pr, Sm, Gd, Tb, Bi)

    Science.gov (United States)

    Massa, Néstor E.; García-Flores, Ali F.; De Sousa Meneses, Domingos; del Campo, Leire; Echegut, Patrick; Fabbris, Gilberto F. L.; Jesús Martínez-Lope, María; Alonso, José Antonio

    2012-05-01

    We report on electronic collective excitations in RMn2O5 (R =Pr, Sm, Gd, Tb) showing condensation starting at and below ˜ TN ˜ TC ˜ 40-50 K. Their origin is understood as partial delocalized eg electron orbitals in the Jahn-Teller distortion of the pyramid dimer with strong hybridized Mn3+-O bonds. Our local probes, Raman, infrared, and x-ray absorption, back the conclusion that there is no structural phase transition at TN ˜ TC. Ferroelectricity is magnetically assisted by electron localization triggering lattice polarizability by unscreening. We have also found phonon hardening as the rare earth is sequentially replaced. This is understood as a consequence of lanthanide contraction. It is suggested that partially f-electron screened rare earth nuclei might be introducing a perturbation to eg electrons prone to delocalize as the superexchange interaction takes place.

  11. Collective phase-like mode and the role of lattice distortions at TN ~TC in RMn2O5 (R= Pr, Sm, Gd, Tb, Bi).

    Science.gov (United States)

    Massa, Néstor E; García-Flores, Ali F; De Sousa Meneses, Domingos; del Campo, Leire; Echegut, Patrick; Fabbris, Gilberto F L; Martínez-Lope, María Jesús; Alonso, José Antonio

    2012-05-16

    We report on electronic collective excitations in RMn(2)O(5) (R =Pr, Sm, Gd, Tb) showing condensation starting at and below ~T(N) ~T(C)~ 40-50 K. Their origin is understood as partial delocalized e(g) electron orbitals in the Jahn-Teller distortion of the pyramid dimer with strong hybridized Mn(3+)-O bonds. Our local probes, Raman, infrared, and x-ray absorption, back the conclusion that there is no structural phase transition at T(N)~T(C). Ferroelectricity is magnetically assisted by electron localization triggering lattice polarizability by unscreening. We have also found phonon hardening as the rare earth is sequentially replaced. This is understood as a consequence of lanthanide contraction. It is suggested that partially f-electron screened rare earth nuclei might be introducing a perturbation to e(g) electrons prone to delocalize as the superexchange interaction takes place.

  12. Cálculos de parâmetros de RMN de organoestananas e do Benzeno sob ação de campo elétrico

    OpenAIRE

    CRUZ, José Brito da

    2010-01-01

    Compostos organoestanho são importantes intermediários em síntese orgânica, além de possuírem atividade biológica e poderem ser utilizados em química de materiais. Logo, a determinação de suas estruturas moleculares é essencial para a racionalização da reatividade química e na determinação do mecanismo de reação. Cálculos quânticos dos parâmetros de RMN (deslocamentos químicos e constantes de acoplamento) são importantes para a atribuição dos sinais para a determinação estrutur...

  13. Structural properties and charge ordered states in RMnO3 (R=La, Pr, Nd, Ca, Sr) and (La, Sr)2NiO4.

    Science.gov (United States)

    Li, J Q; Chen, H Y; Zhang, H R; Yu, H C; Shi, Y G; Liu, L B; Tian, H F; Zhu, Y; Tranquada, J M

    2004-01-01

    Structural distortions arising from the condensations of two essential kinds of phonon modes: the triply degenerate rotational modes (phix, phiy, phiz) of MnO(6) and the doubly degenerate Jahn-Teller active modes (Q1, Q2) have been systematically investigated in the perovskite manganites. Microstructural features associated with certain types of distortions have been observed by transmission electron microscopy (TEM). In RMnO(3) and La(Sr)(2)NiO(4), we characterize the local structure, charge ordered states and orbital ordering by means of low-temperature TEM. We present direct evidence that the stripe modulation in La(Sr)(2)NiO(4) is indeed one-dimensional within each NiO(2) plane. Several typical kinds of defect structures, including antiphase boundaries and the 90 degrees -twin domains, appear commonly in the charge-ordered states.

  14. DETERMINACIÓN RÁPIDA Y PRECISA DEL CONTENIDO DE HIDRÓGENO EN MEZCLAS DE HIDROCARBUROS POR RMN 1H

    Directory of Open Access Journals (Sweden)

    Eliseo Avella

    2011-12-01

    Full Text Available Se presentan y discuten resultados de ladeterminación de hidrógeno en mezclasde hidrocarburos y de fracciones pesadasde petróleo por integración de las señalesen sus espectros RMN 1H de alta resolución.Los resultados muestran la posibilidadde cuantificar de manera rápida yprecisa el hidrógeno en 37 fragmentosestructurales, además del hidrógeno totalen la muestra, mediante aplicación deintervalos de integración unificados. Adiferencia de los métodos publicados enla literatura, la determinación de hidrógenoes posible con menor cantidad demuestra en disolución, con corto tiempode reciclado, d1, sin ajustes estrictos detemperatura ni adición de agente de relajacióno uso de algún estándar de cuantificaciónexterno.

  15. Movilidad de litio en conductores iónicos rápidos analizada mediante espectroscopia RMN

    Directory of Open Access Journals (Sweden)

    Sanz, J.

    2010-02-01

    -red (T1 y spin-spin (T2 con la temperatura, ha permitido deducir los tiempos de residencia de los iones Li en los sitios estructurales. La comparación de estos valores con los deducidos a partir de las conductividades ac y dc, hace posible describir de un modo más preciso la dinámica de los iones. A temperaturas crecientes, los movimientos se vuelven menos correlacionados, produciéndose una disminución de la energía de activación. El análisis de los movimientos a larga distancia requiere medidas a baja frecuencia (medidas de T2 y conductividad-dc. Desviaciones de la conductividad del comportamiento Arrhenius, a menudo observadas en conductores iónicos rápidos, han sido adscritas a transiciones de orden-desorden en las que el movimiento de los iones se hace menos correlacionado. Una medida directa de los coeficientes de difusión ha sido obtenida con la técnica RMN de gradiente de campo pulsado (PFG. Finalmente se analiza la importancia de los fenómenos de percolación de vacantes en los procesos de conducción.

  16. Applications de la résonance magnétique nucléaire (RMN en milieux poreux Dispositif de diagraphie à RMN de résolution centimétrique Nuclear Magnetic Resonance (Nmr Applications in Porous Media an Nmr Logging Apparatus with Centimeter Resolution

    Directory of Open Access Journals (Sweden)

    Locatelli M.

    2006-12-01

    Full Text Available Après un bref rappel sur le concept des mesures de RMN, nous décrivons un dispositif de mesure de la porosité en puits présentant une résolution verticale centimétrique. Des tests effectués avec un dispositif de laboratoire en confirment les potentialités, en particulier au niveau de la vitesse de déplacement qui peut atteindre 1800 pieds/heure. After a brief review of the concept of NMR measurements, we describe an apparatus, with resolution on a scale of centimeters, for measuring well porosity. Laboratory tests confirm the potential of this apparatus, especially its speed, which can attain 1800 feet/hour.

  17. Carl Rogers reflexiones teorico-practicas

    National Research Council Canada - National Science Library

    Duque Camargo, Judith

    2001-01-01

    ...: Psicoterapia, experiencia existencial. *** Toda nuestra sabiduria esta dentro, esa es mi fiel conviccion. Al iniciar el camino por el sendero de la sicologia humanista, inmediatamente me encuentro con un planteamiento que es congruente con mis necesidades humanas y existenciales pero que tambien significa un cambio de posicion frente a mi misma como persona ...

  18. Applications de la résonance magnétique nucléaire (RMN en milieu poreux Lissage des courbes de relaxation RMN du domaine du temps par une méthode discrète et continue Nuclear Magnetic Resonance (Nmr Applications in Porous Media Time-Dependent Nmr Relaxation Curve Smoothing Using a Discrete Continuous Method

    Directory of Open Access Journals (Sweden)

    Le Botlan D.

    2006-12-01

    Full Text Available Dans un champ magnétique hétérogène, le signal RMN de précession libre (FID suit une évolution gaussienne. Le traitement du signal par une méthode discrète peut donner des composantes qui ne correspondent pas à un état physique réel. Par contre l'utilisation d'une méthode de déconvolution continue nous a donné des résultats quantitatifs tout à fait satisfaisants permettant de déterminer les distributions de temps de relaxation correspondant à des états intermédiaires entre les phases solides et liquides. La RMN du domaine du temps peut ainsi être considérée comme une méthode analytique complémentaire des techniques habituellement utilisées pour l'étude de composés complexes hétérogènes ATD, ACD, isothermes de sorption, etc. In a heterogeneous magnetic field, the freely precessing NMR signal (FID describes a Gaussian curve. Processing the signal using a discrete method can give rise to components that do not correspond to a real physical state. However, with a continuous deconvolution method, which gives quite satisfactory quantitative results, it is possible to determine the distributions of relaxation times that correspond to intermediate states between solid and liquid phases. Time-dependent NMR can thus be used to supplement the usual analytical methods, such as DTA, DCA and sorption isotherms, for studying complex heterogeneous compounds.

  19. Theoretical model to determine the energy behavior of test modules at scale of constructions for the efficient use of energy; Modelo teorico para determinar el comportamiento energetico de modulos de prueba a escala de edificaciones para el uso eficiente de la energia

    Energy Technology Data Exchange (ETDEWEB)

    Acoltzi, Higinio; Alvarez, Gabriela [Instituto de Investigaciones Electricas, Cuernavaca, Morelos (Mexico)

    2001-07-01

    In this work a theoretical model of the energy behavior of test modules and its experimental verification is presented. The model determines the history of electrical energy consumption to maintain the comfort conditions in the interior of the modules, with respect to the variation of the materials of ceilings and windows with the purpose of establishing criteria of application of these materials in the construction industry. The measured results of the consumption of the accumulated energy are presented. [Spanish] En este trabajo se presenta un modelo teorico del comportamiento energetico de modulos de prueba y su verificacion experimental. El modelo determina la historia del consumo de energia electrica para mantener las condiciones de confort al interior de los modulos, respecto a la variacion de los materiales de los techos y ventanas, con el objeto de establecer criterios de aplicacion de dichos materiales en la industria de la edificacion. Se presentan los resultados medidos del consumo de energia acumulada.

  20. Thickness calculation software of the thermal insulation in facilities using thermal solar energy; Software para el calculo de espesores del aislante termico en instalaciones de aprovechamiento de energia solar termica

    Energy Technology Data Exchange (ETDEWEB)

    Portillo Jimenez, Canek [Universidad Autonoma de Sinaloa, Culiacan, Sinaloa (Mexico)]. E-mail: cnk@uas.uasnet.mx

    2010-11-15

    It is presented a software application for calculating the thickness of the thermal insulation used in various facilities where there are thermal systems using solar energy. The software facilitates the calculation of the thermal cover thickness over components such as pipes (flat or round), storage and other devices that require thermal protection, installed in outdoors or indoors. The software was programmed in Visual Basic by following the technical specifications of the current regulations in the field. Application examples are performed, obtaining certain results that are discussed briefly. [Spanish] Se presenta un software de aplicacion para el calculo de los espesores de los aislantes termicos, utilizados en diferentes instalaciones donde existen sistemas de aprovechamiento termico de energia solar. El software facilita el calculo del grosor del recubrimiento termico en componentes tales como: tuberias (planas o circulares), depositos acumuladores y otros aparatos que necesiten proteccion termica, instalados en exteriores o en interiores. El software fue programado en Visual Basic siguiendo las especificaciones tecnicas de la normatividad vigente en la materia. Se realizan ejemplos de aplicacion, donde se obtienen ciertos resultados de los cuales se hace una breve discusion.

  1. Critical behavior of RMn2O5 oxides near the magnetic phase transition to a structure incommensurate in two spatial directions

    Science.gov (United States)

    Men'shenin, V. V.

    2013-10-01

    A phase transition from the paramagnetic state to the long-period magnetic structure in RMn2O5 oxides with the star of the wave vector determining the incommensurability of long-range magnetic order in two spatial directions has been investigated. An effective Hamiltonian of the system that allows one to describe this transition in the framework of the renormalization group approach has been constructed. It has been shown that there is a stable critical point of transformations of this group at which there occurs a second-order phase transition. The critical indices have been found. The obtained results have been compared with the results for phase transitions occurring in these oxides in accordance with the star of the wave vector, which provides incommensurability in one of the spatial directions. It has been found that fluctuations of the four-component order parameter due to the low spatial symmetry of these compounds do not change the order of the phase transition, which was found in terms of the Landau theory.

  2. Magnetic and transport properties of R(Mn, In)2 (R—rare-earth metals) with AlB2-structure type

    Science.gov (United States)

    Dzevenko, M.; Havela, L.; Prokleška, J.; Svoboda, P.; Miliyanchuk, K.; Kalychak, Y.

    2007-04-01

    We studied the crystal structure and magnetic properties of ternary rare-earth R(Mn,In) 2 compounds (R=Y, La, Ce, Tb-Tm, Lu), which crystallize in the AlB 2-structure type with approximate stoichiometry RMn 0.67In 1.33, but adopting a variable Mn deficiency. YMn 0.92In 1.08 orders antiferromagnetically below TN ≈ 247 K, CeMn 0.65In 1.35 is ferromagnetic with TC=134 K. The compounds with magnetic rare earths tend to a glassy magnetic state, presumably due to the disorder in the Mn/In sublattice together with competing exchange interactions. The disorder has also a dramatic impact on the temperature dependence of the electrical resistivity, which is rather flat due to a strong scattering. The absence of long-range order was proved also by specific-heat measurements. Hydrogen absorption, tested for several compounds, led to the synthesis of LaMn 0.49In 1.51H 0.75(5).

  3. Exchange interactions in the perovskites Ca1-xSrxMnO3 and RMnO3 (R=La,Pr,Sm)

    Science.gov (United States)

    Zhou, J.-S.; Goodenough, J. B.

    2003-08-01

    Measurement of the variation of the Néel temperature TN with pressure P and the compressibility κ of the orbitally ordered Mn(III)O3 array of the RMnO3 family (R=La,Pr,Sm) and of the Mn(IV)O3 array of the Ca1-xSrxMnO3 system have enabled the determination for each of a systematic increase in κ, the magnitude of the Bloch parameter αB≡d ln TN/d ln V, and TN with decreasing bending of the (180°-φ) Mn-O-Mn bond angles. The data demonstrate that the anomalously high value of -αB=5.5 reported previously for LaMnO3 is not due to orbital order and its attendant anisotropic magnetic order. A higher |αB| than 3.3 and an increasing compressibility characterize a system on the approach from the localized-electron side to a first-order transition from localized to itinerant electronic behavior. Moreover, the puzzling empirical relationship TN˜ for the π-bonding Mn(IV)O3 array is rationalized by dominance of a semicovalent exchange term over the superexchange term in the perturbation theory for the spin-spin interatomic interactions. The data also provide indirect evidence for a transition from in-phase to out-of-phase stacking along the c axis of the (001)-plane orbital ordering that has been predicted by Mizokawa, Khomskii, and Sawatzky.

  4. Computer program for the calculation of stresses in rotary equipment discs; Programas de computo para el calculo de esfuerzos en discos de equipo rotatorio

    Energy Technology Data Exchange (ETDEWEB)

    Gutierrez Delgado, Wilson; Kubiak, Janusz; Serrano Romero, Luis Enrique [Instituto de Investigaciones Electricas, Cuernavaca (Mexico)

    1990-12-31

    In the preliminary design and diagnosis of rotary machines is very common to utilize simple calculation methods for the mechanical and thermal stresses, dynamic and thermodynamic analysis and flow of fluids in this machines (Gutierrez et al., 1989). The analysis with these methods provides the necessary results for the project initial stage of the machine. Later on, more complex tools are employed to refine the design of some machine components. In the Gutierrez report et al., (1989) 34 programs were developed for the preliminary design and diagnosis of rotating equipment; in this article, one of them is presented in which a method for the analysis of mechanical and thermal stresses is applied in discs of uniform or variable thickness that are normally found in turbomachines and rotary equipment. [Espanol] En el diseno preliminar y diagnostico de maquinas rotatorias es muy comun emplear metodos de calculo sencillos para el analisis de esfuerzos mecanicos y termicos, analisis dinamico y termodinamico y de flujo de fluidos en estas maquinas (Gutierrez et al., 1989). El analisis con estos metodos proporcionan los resultados necesarios para la etapa del proyecto inicial de la maquina. Posteriormente, para refinar el diseno de algunos componentes de la maquina, se aplican las herramientas mas complejas. En el informe de Gutierrez et al., (1989) se desarrollan 34 programas para el diseno preliminar y diagnostico de equipo rotatorio; en este articulo, se presenta uno de ellos, en el que se emplea un metodo para el analisis de esfuerzos mecanicos y termicos en discos de espesor constante o variable que se encuentran comunmente en turbomaquinas y en equipos rotatorios.

  5. PCRELAP5: data calculation program for RELAP 5 code; PCRELAP5: programa de calculo dos dados de entrada para o codigo RELAP5

    Energy Technology Data Exchange (ETDEWEB)

    Silvestre, Larissa Jacome Barros

    2016-07-01

    Nuclear accidents in the world led to the establishment of rigorous criteria and requirements for nuclear power plant operations by the international regulatory bodies. By using specific computer programs, simulations of various accidents and transients likely to occur at any nuclear power plant are required for certifying and licensing a nuclear power plant. Based on this scenario, some sophisticated computational tools have been used such as the Reactor Excursion and Leak Analysis Program (RELAP5), which is the most widely used code for the thermo-hydraulic analysis of accidents and transients in nuclear reactors in Brazil and worldwide. A major difficulty in the simulation by using RELAP5 code is the amount of information required for the simulation of thermal-hydraulic accidents or transients. The preparation of the input data requires a great number of mathematical operations to calculate the geometry of the components. Thus, for those calculations performance and preparation of RELAP5 input data, a friendly mathematical preprocessor was designed. The Visual Basic for Application (VBA) for Microsoft Excel demonstrated to be an effective tool to perform a number of tasks in the development of the program. In order to meet the needs of RELAP5 users, the RELAP5 Calculation Program (Programa de Calculo do RELAP5 - PCRELAP5) was designed. The components of the code were codified; all entry cards including the optional cards of each one have been programmed. In addition, an English version for PCRELAP5 was provided. Furthermore, a friendly design was developed in order to minimize the time of preparation of input data and errors committed by users. In this work, the final version of this preprocessor was successfully applied for Safety Injection System (SIS) of Angra 2. (author)

  6. Structure par RMN d'un complexe AlcR(1-60)-ADN: Reconnaissance du petit sillon par la partie N-terminale

    Science.gov (United States)

    Cahuzac, B.; Félenbok, B.; Guittet, E.

    1999-10-01

    Aspergillus nidulans is a filamentous fungus able to use ethanol as sole energy source. The activation of the ethanol regulon genes expression is mediated by the AlcR protein. Its DNA-binding domain is located in the N-terminus (residues 1 to 60), and its NMR solution structure shows a global zinc binuclear cluster fold, with two helices in addition to the basic binuclear motif. A small number of crystallographic structures of DNA complexes of binuclear cluster proteins is yet known, and points out the major groove and the first helix as the principal sites of interaction on the DNA and the protein respectively. In this article we show evidences that the N-terminus of the protein is involved in binding to the minor groove. Aspergillus nidulans est un champignon filamenteux capable d'utiliser l'éthanol comme source unique d'énergie. La protéine AlcR est responsable de l'activation de l'expression des gènes du régulon éthanol. Le domaine de liaison à l'ADN est situé dans la partie N-terminale de la protéine (a.a. 1 à 60), et sa structure déterminée par RMN en solution montre un repliement global en bouquet binucléaire à zinc, avec deux hélices supplémentaires par rapport au motif de base. Alors que les structures déjà connues de complexes ADN - bouquets binucléaires permettent de situer dans le grand sillon la quasi-totalité des interactions, nous montrons dans la présente étude l'implication du début de la séquence dans la reconnaissance du petit sillon de l'ADN (a.a. 5 et 6).

  7. Positive magnetoresistance and large magnetostriction at first-order antiferro-ferromagnetic phase transitions in RMn{sub 2}Si{sub 2} compounds

    Energy Technology Data Exchange (ETDEWEB)

    Gerasimov, E G; Mushnikov, N V [Institute of Metals Physics, Ural Division of the Russian Academy of Science, Sofia Kovalevskaya Street, 18, 620041 Ekaterinburg (Russian Federation); Koyama, K; Watanabe, K [High Field Laboratory for Superconducting Materials HFLSM, Institute for Materials Research, Tohoku University, Sendai 980-8577 (Japan); Kanomata, T [Department of Applied Physics, Faculty of Engineering, Tohoku Gakuin University, Tagajo, Miyagi 985 (Japan)], E-mail: gerasimov@imp.uran.ru

    2008-11-05

    The magnetostriction and magnetoresistance associated with the field-induced and spontaneous first-order antiferro-ferromagnetic (AF-F) phase transitions have been studied for quasi-single-crystalline samples of La{sub 0.25}Sm{sub 0.75}Mn{sub 2}Si{sub 2}, La{sub 0.25}Y{sub 0.75}Mn{sub 2}Si{sub 2} and La{sub 0.27}Y{sub 0.73}Mn{sub 2}Si{sub 2} compounds with natural layered ThCr{sub 2}Si{sub 2}-type structure. It was found that both the spontaneous and field-induced AF-F transitions are accompanied by a large volume magnetostriction {delta}V/V{approx}2 x 10{sup -3} and anisotropic linear changes of the lattice parameters {delta}a/a{approx}1.6 x 10{sup -3}, {delta}c/c{approx}-0.75 x 10{sup -3}. The field-induced AF-F magnetic phase transition has been observed in magnetic fields applied both along the c-axis and in the basal plane, and the magnetostriction value is virtually independent of the direction of applied field. It has been found also that the magnetoresistance is positive in these compounds (the value of the electrical resistance in the ferromagnetic state is higher than that in the antiferromagnetic state) for the fields applied both along the c-axis and in the basal plane. The value of the magnetoresistance observed along the c-axis is 30 times as high as that in the basal plane. The obtained results indicate that the electronic band structure changes are likely responsible for the AF-F magnetic phase transitions observed in the RMn{sub 2}X{sub 2} compounds.

  8. Torque calculation in the induction motor with the finite element method; Calculo del par en el motor de induccion con el metodo del elemento finito

    Energy Technology Data Exchange (ETDEWEB)

    Castillo Diaz, Ramon

    2002-06-15

    In this work the method of the finite element is applied to the bi-dimensional analysis of the induction motor in operation in steady state, excited by sine sources of laminar currents and sine sources of voltage. The analysis is focused mainly in the calculation of the electromagnetic torque. The topics of electromagnetic theory are covered and in an idealized model of the induction motor, analytically and numerically with the method of the finite element, in the variant method of Galerkin, the vectorial potential and the torque are calculated. The results obtained with the analytical and numerical methods are compared. Three formulations are developed to calculate the torque with the method of the finite element, using triangular elements of first order, based in the equation of force of Lorentz, the Maxwell tensor and the principle of the virtual work. Finally, a motor of induction of real characteristics is simulated, assuming it is connected to a three-phase voltage source. In this motor it is analyzed the convergence and the evolution in the results obtained of the torque with different discretions, and the torque-velocity performance curve is calculated. [Spanish] En este trabajo se aplica el metodo del elemento finito al analisis bidimensional del motor de induccion en operacion en estado estable, excitado por fuentes de corriente laminar senoidales y fuentes de voltaje senoidales. El analisis se enfoca principalmente en el calculo del par electromagnetico. Se tratan los topicos de teoria electromagnetica involucrados y en un modelo idealizado del motor de induccion, se calculan analitica y numericamente con el metodo del elemento finito, en la variante metodo de Galerkin, el potencial vectorial y el par. Se comparan resultados obtenidos con los metodos analiticos y numericos. Se desarrollan tres formulaciones para calcular el par con el metodo del elemento finito, utilizando elementos triangulares de primer orden, basadas en la ecuacion de fuerza de

  9. Large electric polarization in high pressure synthesized orthorhombic manganites RMnO3 (R=Ho,Tm,Yb and Lu) by using the double-wave PE loop measurements

    Science.gov (United States)

    Chai, Y. S.; Oh, Y. S.; Manivannan, N.; Yang, Y. S.; Kim, Kee Hoon; Feng, S. M.; Wang, L. J.; Jin, C. Q.

    2009-03-01

    The magnitude of electric polarization via the conventional pyroelectric current and/or PE loop measurements often is ambiguous due to resistive components of the sample. To avoid this, a new technique called the double-wave method has been recently developed [1], in which only hysteretic PE components can be measured. Using this technique, we have measured the ferroelectric polarization of the orthorhombic RMnO3 (R=Ho, Tm, Yb, and Lu) synthesized under high pressure. Large remnant polarization Pr up to 920 μC/m^2 is observed at 10 K for LuMnO3. Furthermore, the Pr vs. temperature data from the PE loop has shown consistency with that measured through the pyroelectric current measurements, supporting a theoretical prediction of large polarization in the E-type spin structure in this system [2]. We also discuss the influence of thermal histories on the ferroelectric domain dynamics and possible internal bias field effects originating from oxygen vacancies in RMnO3. [1] M. Fukunaga, et al. J. Phys. Soc. Jpn. 77, 064706 (2008). [2] I. A. Sergienko, et al. Phys. Rev. Lett., 97, 227204 (2006)

  10. Calculation of economic viability of alternative energy sources considering its environmental costs for small communities of Northeast Brazil; Calculo de viabilidade economica de fontes alternativas de energia considerando seus custos ambientais para pequenas comuidades da regiao nordeste brasileira

    Energy Technology Data Exchange (ETDEWEB)

    Stecher, Luiza Chourkalo

    2014-09-01

    There has been an increasing concern about current environmental issues caused by human activity, as the world searches for development. The production of electricity is an extremely relevant factor in this scenario since it is responsible for a large portion of the emissions that cause the greenhouse effect. Due to this fact, a sustainable development with alternative energy sources, which are attractive for such purpose, must be proposed, especially in places that are not supplied by the conventional electricity grid such as many communities in the Northeast Brazil. This work aims to calculate the environmental cost for the alternative sources of energy - solar, wind and biomass - during electricity generation, and to estimate the economic feasibility of those sources in small communities of Northeast Brazil, considering the avoided costs. The externalities must be properly identified and valued so the costs or benefits can be internalized and reflect accurately the economic feasibility or infeasibility of those sources. For this, the method of avoided costs was adopted for the calculation of externalities. This variable was included in the equation developed for all considered alternative energy sources. The calculations of economic feasibility were performed taking the new configurations in consideration, and the new equation was reprogrammed in the Programa de Calculo de Custos de Energias Alternativas, Solar, Eolica e Biomassa (PEASEB). The results demonstrated that the solar photovoltaic energy in isolated systems is the most feasible and broadly applicable source for small communities of Northeast Brazil. (author)

  11. PREPARO DE SEMENTES PARA DETERMINAÇÃO DO TEOR DE ÓLEO PELO MÉTODO DE RMN EM SEIS VARIEDADES DE ALGODOEIRO SEED PREPARE FOR OIL CONTENT DETERMINATION BY NMR METHOD IN SIX COTTON VARIETIES

    Directory of Open Access Journals (Sweden)

    ROSE MARRY ARAÚJO GONDIM-TOMAZ

    1998-01-01

    Full Text Available No presente trabalho, foram realizados estudos comparativos de métodos de preparação de sementes de algodoeiro, com a finalidade de selecionar aquele com melhores condições para determinação do teor de óleo por ressonância magnética nuclear (RMN. Os métodos estudados foram os seguintes: o deslintamento químico com ácido sulfúrico concentrado, o da flambagem e o da semente com línter, que foi utilizada como parâmetro sem tratamento. Dos três, optou-se pelo tratamento químico, por eliminar a interferência do línter. Por esse método, determinaram-se os teores de óleo em sementes de seis variedades do algodoeiro herbáceo - obtidas do Ensaio Nacional de Variedades, sendo doze realizados no ano agrícola de 1994/95 e doze, em 1995/96: CNPA Precoce 2, IAPAR 71 PR3, CNPA 7H, CS 50, IAC 20 e IAC 22. O teor de óleo foi determinado pela técnica de RMN. As variedades estudadas apresentaram valores médios decrescentes no teor de óleo, na seguinte ordem: IAPAR71 PR3, IAC 20, CNPA 7H, CS 50, IAC 22 e CNPA Precoce 2.Three comparative methods (chemical seed-delinting with sulphuric acid solution, flaming and seed with linter to prepare cotton seeds for oil determination by the Nuclear Magnetic Resonance (NMR technique were considered. The chemical treatment with sulphuric acid was the best as long the linter interference was eliminated. The seed oil contents were determined by the NMR method in six cotton varieties from the national variety test. The IAPAR 71 PR3 and IAC 20 varieties presented the highest oil content followed by the CNPA 7H, CS 50, IAC 22 and CNPA Precoce 2.

  12. COMUNICACIÓN EN SALUD: CONCEPTOS Y MODELOS TEORICOS

    Directory of Open Access Journals (Sweden)

    Iván Ríos Hernández

    2011-01-01

    Full Text Available A través de este artículo de revisión de tema se analiza el concepto comunicación en salud y algunas de las definiciones esbozadas hasta el momento por organismos internacionales y expertos del tema. Se presenta una mirada crítica y reflexiva sobre algunos de los principales modelos teóricos desarrollados en el campo de la comunicación en salud. Se esboza un análisis del paradigma de la Comunicación para el Cambio Social y se compara con las otras teorías y modelos de comunicación en salud discutidos en el escrito. Luego del análisis reflexivo se concluye que el apoderamiento de las comunidades en las estrategias de prevención de enfermedades, representa un reto para los estudios concernientes a las teorías y modelos que tratan de explicar de forma simplificada los elementos inmersos en un proceso de comunicación en salud.

  13. PROPIEDADES ELECTRONICAS Y ESTRUCTURALES DE NANOCINTAS DE FLUOROGRAFENO; ESTUDIO TEORICO

    OpenAIRE

    RUIZ-TAGLE GUTIERRES, IGOR ALBERTO

    2013-01-01

    Los nanomateriales basados en grafeno y grafano han adquirido gran relevancia últimamente. Hoy se les sindica como los sustitutos del silicio en el diseño de nanoestructuras para computación cuántica, autómatas celulares o compuertas lógicas. Para desarrollar este tipo ele aplicaciones es importante el identificar y caracterizar estructuras que se comporten como arreglos de puntos cuánticos o que puedan ser utilizados como filtros ele espín. Esta investigación tiene por objeto, estudiar...

  14. 误诊为急性结石性胆囊炎31例病例分析%The analysis of misdiagnosed as acute calculos cholecystitis in 31 cases.

    Institute of Scientific and Technical Information of China (English)

    陈永友

    2012-01-01

    Objective To analyze and explore the causes of misdiagnosed as acute calculos cholecystitis. Methods Thirty - one cases misdiagnosed as acute calculous cholecystitis in our hospital from July 2000 to May 2012 were retrospectively analyzed and summarized. Results Thirty - one patients with cholecystolithiasis were misdiagnosed as acute calculous cholecystitis, The final diagnosis of misdiagnosis cases: 6 cases of acute myocardial infarction , 5 cases of herpes zoster, 4 cases of carcinoma of gallbladder, 3 cases of high - position appendicitis, 2 cases of pancreatitis, 2 cases of pneumonia, 2 cases of colon tumor, 2 cases of upper digestive tract perforation, 2 cases of renal calculus, 1 case of dissection of aorta, 1 case of pleuritis, 1 case of ascariasis of biliary tract. Conclusion Dont detailed inquest the case history, examine the body carelessly, lack of relevant knowledge and experience, ignoring the other disease diagnosis while gallstones found were the main causes of misdiagnosis.%目的 分析、总结其他疾病误诊为急性结石性胆囊炎的原因,积累经验.方法 对2000年7月至2012 年5月收治的31例临床误诊为急性结石性胆囊炎病例进行回顾性分析、总结.结果 31例患者均因原有胆囊结石而误诊为急性结石性胆囊炎.误诊疾病的最终诊断为:急性心肌梗死6例(19.35%),带状疱疹5例(16.13%),胆囊癌4例(12.9%),高位阑尾炎3例(9.68%),胰腺炎2例(6.45%),肺炎2例(6.45%),结肠肿瘤2例(6.45%),上消化道穿孔2例(6.45%),右肾结石2例(6.45%),主动脉夹层1例(3.22%),胸膜炎1例(3.22%),胆道蛔虫1例(3.22%).结论询问病史不详细、查体不仔细、缺少对相关疾病鉴别诊断的知识和经验、发现胆囊结石而忽略其它疾病诊断是造成误诊的主要原因.

  15. Calculation of the temperature distribution and thermal stresses in a gas turbine nozzle cooled by air film; Calculo de la distribucion de temperaturas y esfuerzos termicos en una tobera de turbina de gas enfriada por pelicula de aire

    Energy Technology Data Exchange (ETDEWEB)

    Hernandez R, Alejandro; Garcia I, Rafael; Mazur C, Zdislaw [Instituto de Investigaciones Electricas, Cuernavaca, Morelos (Mexico)

    2004-07-01

    temperaturas. Con las temperaturas correctamente importadas, se realizaron las simulaciones para el calculo de los esfuerzos termicos en la tobera.

  16. Validation of Hiriart equation to compute steam production by the lip pressure method; Validacion de la ecuacion de Hiriart para calculo de gasto de vapor por el metodo de presion de labio

    Energy Technology Data Exchange (ETDEWEB)

    Flores Armenta, Magaly [Gerencia de Proyectos Geotermoelectricos de la Comision Federal de Electricidad, Morelia (Mexico)

    1996-09-01

    Mainly in new geothermal wells, it is necessary to evaluate the production in a very fast, simple and not expensive way, to know the convenience to install surface equipment, such as silencers and separators, to drive the steam to the commercial gathering system. In practice, one of the most known methods is the lip pressure one, which requires a simple set of installations. The objective of this paper is to validate the steam flow rate calculated by the lip pressure method, with respect to the ASME method. The ASME method is known for its accuracy, and is done by measuring the steam and liquid after a high pressure separator, by an orifice plate of known diameter and a triangular weir. Results of the validation show up the feasibility of application of the lip pressure method by using a simple adjustment equation. Percentage of mistake results less than 1%, without any notable influence of the production enthalpy. That equation to be applied in a general case, is as follows: Q{nu} =(20642)(F*P*D{sup 2}/{radical}h-2000). For the particular case of the Los Azufres geothermal field, the equation is: Q{nu}= 810*P*D{sup 2} [Espanol] En los pozos geotermicos, principalmente en los nuevos, es necesario evaluar su produccion de manera rapida, sencilla y economica, para determinar la conveniencia de instalar equipo superficial, como separadores, silenciadores, etc., que permita la integracion del vapor al sistema comercial de generacion electrica. Para fines practicos uno de los metodos mas conocidos es el de presion de labio, que solo requiere un arreglo sencillo de instalaciones superficiales. En este documento se validan y ajustan los calculos de produccion de vapor por ese metodo de presion de labio, con respecto a las mediciones exactas efectuadas con el metodo ASME. Este ultimo es reconocido internacionalmente por su precision, y se lleva a cabo separando la mezcla obtenida en superficie en un recipiente a presion para medir el vapor a traves de una placa de orificio

  17. Características estruturais de ácidos húmicos isolados de solos com adição de resíduos orgânicos de origem urbana: composição elementar, análise de RMN 13C e Pi-CG/EM

    Directory of Open Access Journals (Sweden)

    L. P. Canellas

    2002-06-01

    Full Text Available Foram avaliadas as alterações nas características estruturais de ácidos húmicos (AH decorrentes da adição de matéria orgânica de resíduos urbanos. Os AH foram extraídos da camada superficial (0-20 cm de um Argissolo Vermelho-Amarelo (Seropédica, RJ e de um Latossolo Vermelho Amarelo (Piraí, RJ, ambos tratados com o equivalente a 80 t ha-1 (em base seca de composto de lixo urbano e lodo de estação de tratamento de esgotos. O tempo de incubação em laboratório foi de 24 semanas à temperatura ambiente e umidade mantida na capacidade de campo. Para caracterizar os AH, foram utilizadas a análise elementar, a ressonância magnética nuclear (RMN de 13C e Pirólise acoplada à cromatografia gasosa e a espectrometria de massas (Pi-CG/EM. A análise de RMN 13C permitiu observar alterações na composição molecular dos AH de forma clara, principalmente, pelo aumento do teor de C mono e di oxigenados (δC 50-110 e pela diminuição dos teores de grupos CH2 e CH3 (δC 50-110. O aumento no teor de carboidratos evidencia a presença de estruturas mais lábeis nos AH com adição dos resíduos. Em adição, a técnica de Pi-CG/EM permitiu verificar diferenças qualitativas significativas nos compostos orgânicos, provenientes da fragmentação térmica dos AH com incorporação de novas estruturas, sobretudo da fração lipídica e de derivados de carboidratos (furanos, nas amostras de solos tratados com ambos os resíduos orgânicos. O uso em conjunto das técnicas analíticas de RMN 13C e de Pi-CG/EM foi eficiente para avaliar as mudanças na composição molecular de ácidos húmicos decorrentes da adição de resíduos orgânicos de origem urbana.

  18. Avaliação de características de ácidos húmicos de resíduos de origem urbana: I. métodos espectroscópicos (UV-Vis, IV, RMN 13C-CP/MAS e microscopia eletrônica de varredura

    Directory of Open Access Journals (Sweden)

    L. P. Canellas

    2000-12-01

    Full Text Available Foram caracterizados fisico-quimicamente ácidos húmicos, obtidos de composto de resíduos sólidos urbanos (AH-CRSU e de lodo de estação de tratamento de esgoto (AH-LETE, ambos produzidos na cidade do Rio de Janeiro, por meio da análise da composição elementar, acidez total, de dados espectroscópicos (UV-Vis; IV, RMN de 13C-CP/MAS e microscopia eletrônica de varredura (MEV. A análise das características estruturais revelou diferenças entre os AHs estudados. A presença de sistemas aromáticos foi observada por meio da espectroscopia de UV-Vis, indicando sistemas mais substituídos nos AH-LETE. A espectroscopia na região do infravermelho (IV mostrou a presença de estruturas alifáticas nos AHs e maior complexidade nos sinais de absorção devida a polissacarídeos nos AH-CRSU. Além disso, foram observados grupos OH, COOH, COO-, CO2NH2, e confirmada a presença de sistemas aromáticos. Com a análise de RMN de 13C-CP/MAS, foi possível verificar as diferenças quantitativas nos diferentes tipos de carbono. Os AH-LETE apresentaram maior quantidade de grupos aromáticos e de COOH. A análise de RMN de 13C-CP/MAS também mostrou presença de polissacarídeos, N em aminoácidos e grupamentos OCH3. O conjunto de propriedades avaliadas permitiu indicar que a fração ácidos húmicos dos resíduos é "do tipo" ou "análoga" aos ácidos húmicos de origem pedogênica.

  19. Systems for the calculation of electrical parameters and energy efficiency for high-capacity hydroelectric generators; Sistemas para el calculo de parametros electricos y eficiencia energetica para generadores hidroelectricos de gran capacidad

    Energy Technology Data Exchange (ETDEWEB)

    Reyes Martinez, Oscar Alfonso; Pascacio de los Santos, Alberth; Perez Abad, Carlos Alberto [Instituto de Investigaciones Electricas, Cuernavaca, Morelos (Mexico); Leon Rivera, Nicolas [CFE-LAPEM, Irapuato, Guanajuato (Mexico)

    2012-07-01

    construccion es la Central Hidroelectrica La Yesca, el cual concluira a finales de 2012 y consiste en dos generadores electricos de 375 MW, 17 kV. Sera el segundo en potencia y el tercero en generacion electrica en el sistema. De acuerdo con las normas nacionales e internacionales, debe efectuarse un conjunto de pruebas estaticas y dinamicas en estos generadores antes de la puesta en servicio, para asegurar su operacion apropiada. La prueba de resistencia de alto voltaje del devanado del estator, la prueba de corto circuito subito trifasico y el calculo de eficiencia energetica son algunas de las pruebas mas importantes por realizar en un nuevo generador electrico. Estas pruebas son dificiles de efectuar en sitio debido a la capacidad del equipo requerido, por lo que muy pocas companias en el mundo pueden conducirlas.

  20. Calculation of attenuation by rain using the DAH model and diameter of antennas for the Ka Band in Mexico; Calculo de atenuacion por lluvia usando el modelo DAH y diametro de antena para Banda Ka en Mexico

    Energy Technology Data Exchange (ETDEWEB)

    Landeros-Ayala, S.; Neri-Vela, R; Cruz-Sanchez, H.; Hernandez-Bautista, H. [Universidad Nacional Autonoma de Mexico, Mexico, D.F. (Mexico)

    2002-03-01

    Fatim Haidara), combinado con los mapas globales de distribucion de lluvia de Crane, para el calculo de la atencion por lluvia en sistema de comunicacion por satelite que operen en la Banda Ka. Ademas, se proponen diametros de antena para los sistemas de comunicaciones en Banda Ka en diferentes localidades de la Republica Mexicana, empleando para ello, los margenes de atencion por lluvia obtenidos a trav del Modelo DAH, y usando como referencia las caracteristicas del satelite de comunicaciones ANIK F2 y de una estacion terrena VSAT.Se muestra una fig. de la atenuacion por lluvia a 27.5 gHz y de los diametros de antena para banda Ka en Mexico. Se da una tabla de la atenuacion por lluvia a 29.5 GHz y a 20.2 GHz.

  1. Avaliação de características de ácidos húmicos de resíduos de origem urbana: I. métodos espectroscópicos (UV-Vis, IV, RMN 13C-CP/MAS) e microscopia eletrônica de varredura

    OpenAIRE

    L. P. Canellas; Santos,G. A.; Moraes,A. A.; V. M. Rumjanek; Olivares,F. L.

    2000-01-01

    Foram caracterizados fisico-quimicamente ácidos húmicos, obtidos de composto de resíduos sólidos urbanos (AH-CRSU) e de lodo de estação de tratamento de esgoto (AH-LETE), ambos produzidos na cidade do Rio de Janeiro, por meio da análise da composição elementar, acidez total, de dados espectroscópicos (UV-Vis; IV, RMN de 13C-CP/MAS) e microscopia eletrônica de varredura (MEV). A análise das características estruturais revelou diferenças entre os AHs estudados. A presença de sistemas aromáticos...

  2. Efeito de Diferentes Métodos de Cálculo de Propriedades Magnéticas na Atribuição Inequívoca dos Sinais de RMN e da Estereoquímica Relativa dos Epóxidos de -Pineno e Carvona

    OpenAIRE

    QUEIROZ JUNIOR, L. H. K.

    2009-01-01

    O trabalho aqui abordado visa utilizar cálculos teóricos de tensores de blindagem () e constantes de acoplamento spin-spin (J) através de diferentes métodos teóricos (GIAO, CSGT, IGAIM e SGO), com o intuito tanto de efetuar um estudo comparativo dos métodos em questão, quanto de utilizar os dados obtidos através destes como suporte para a atribuição inequívoca dos sinais de RMN de 1H e de 13C e da estereoquímica relativa de epóxidos. Em foco neste estudo estão dois compostos: o ep...

  3. Optimisation d'une nanotechnologie liée à la post combustion automobile : étude par EXAFS, RMN & DRX de catalyseurs industriels Zn/Al2O3

    Science.gov (United States)

    Bazin, D.; Revel, R.; Klur, I.; Pourpoint, A.

    2002-07-01

    In this paper, we report a structural characterisation of an industrial catalyst conducted through the combined use of different characterisation techniques i.e. ^{27}Al Nuclear Magnetic Resonance (NMR), X-Ray Diffraction (XRD) and High Resolution Transmission Electronic Microscopy (HRTEM). The usual characterisation techniques help to restrict the problem but do not precisely show the structure of the supported system "Zn"/Al2O3. For example, ^{27}Al NMR shows the occupation of tetrahedral site by zinc through a modification of the occupation of tetrahedral and octahedral site by aluminium atoms. Unfortunately this technique is not able to determine the size of the zinc based metal oxide cluster. A more appropriate technique, such as X-ray absorption spectroscopy is thus necessary. In fact, we show that only the complete set of data leads to major information regarding the cation distribution as well as the electronic state of the metal atoms. Nous présentons une étude de matériaux nanodivisés industriels initiée à l'aide de techniques de caractérisation classiques (Microscopie électronique haute résolution, Résonance Magnétique Nucléaire, Diffraction des rayons X) et affinée par une technique spécifique au rayonnement synchrotron, la spectroscopie d'absorption X. Le catalyseur industriel est obtenu par dispersion à l'échelle atomique d'atomes de zinc à la surface d'une yc alumine de grande surface spécifique (> 200m^2/g). Le fait qu'une similarité structurale existe entre le support et le composé défini obtenu par insertion du cation dans la matrice rend quasi-inopérante la DRX classique. La RMN de l'aluminium par contre constitue une technique de choix puisque l'occupation par le zinc de sites tétraédriques se traduit par l'occupation plus conséquente de sites octaédriques par l'aluminium. Néanmoins, la taille des cristallites de "ZnAl2O4", les possibilités d'inversion (limitées ici car le zinc occupe préférentiellement les sites t

  4. Fósforo num Cambissolo cultivado com cana-de-açúcar por longo tempo: II - análise de ácidos húmicos por RMN 31P Phosphorus in an Inceptsoil under long-term sugarcane: II - humic acid analysis by NMR 31P

    Directory of Open Access Journals (Sweden)

    Jader Galba Busato

    2005-12-01

    Full Text Available Sistemas de manejo da lavoura de cana-de-açúcar que favoreçam a matéria orgânica do solo podem aumentar o conteúdo de nutrientes disponíveis e diminuir a necessidade de aplicação de fertilizantes industriais. Apesar da importância dos componentes orgânicos no fornecimento de P, pouco se conhece sobre a sua dinâmica em ambientes tropicais. O objetivo deste trabalho foi identificar, por meio da ressonância magnética nuclear (RMN 31P, as espécies de P nos ácidos húmicos de um Cambissolo Háplico Ta eutrófico vértico, localizado no Município de Campos dos Goytacazes, norte do Estado do Rio de Janeiro, e cultivado com cana-de-açúcar com preservação do palhiço e adição de vinhaça por longo tempo. Por meio da análise de RMN 31P foi possível observar acúmulo de P orgânico em formas mais facilmente mineralizadas nas áreas com preservação de matéria orgânica, tal como P em ligações diésteres. Nas áreas de cana queimada, houve maior participação de espécies orgânicas mais estáveis, como o ortofosfato em ligações monoésteres. Os resultados da espectroscopia de RMN 31P mostram que, nas áreas com maior aporte de resíduo orgânico (i.e., cana crua e cana queimada com adição de vinhaça, os ácidos húmicos constituem uma reserva importante de P orgânico prontamente disponível. Já, nas áreas de cana queimada, o acúmulo de P orgânico recalcitrante nos ácidos húmicos indica utilização do P-lábil das substâncias húmicas como fonte importante para nutrição das plantas.Crop management systems that favor soil organic matter can improve the available nutrient content for plants and reduce the use of industrial fertilizer. Despite the importance of organic compounds as a P source, little is known about its dynamics in tropical environments. The objective of this study was to identify organic P species present in humic acids by NMR 31P analysis in a fine clay Fluventic Eutrochrepts in Campos dos

  5. Neutron diffraction study on PrMn{sub 2-x}Fe{sub x}Ge{sub 2} and general magnetic phase diagram for RMn{sub 2-x}Fe{sub x}Ge{sub 2} (R: La-Sm)

    Energy Technology Data Exchange (ETDEWEB)

    Dincer, I. [Department of Engineering Physics, Faculty of Engineering, Ankara University, TR-06100 Besevler, Ankara (Turkey)]. E-mail: idincer@eng.ankara.edu.tr; Elmali, A. [Department of Engineering Physics, Faculty of Engineering, Ankara University, TR-06100 Besevler, Ankara (Turkey); Elerman, Y. [Department of Engineering Physics, Faculty of Engineering, Ankara University, TR-06100 Besevler, Ankara (Turkey); Ehrenberg, H. [Institute for Materials Science, Darmstadt University of Technology, Petersenstrasse 23, D-64287 Darmstadt (Germany); Fuess, H. [Institute for Materials Science, Darmstadt University of Technology, Petersenstrasse 23, D-64287 Darmstadt (Germany); Andre, G. [Laboratoire Leon Brillouin (CEA-CNRS), CEN-Saclay, 91191 Gif-Sur-Yvette (France)

    2006-06-08

    We have investigated the magnetic structures and phase transitions of PrMn{sub 2-x}Fe{sub x}Ge{sub 2} (0-bar x-bar 1) by the temperature dependence of weak-field magnetization and powder neutron diffraction. For the x=0.6 sample, a typical SmMn{sub 2}Ge{sub 2}-like magnetic behavior is observed. The magnetic structures of the samples with x=0.6, 0.8 and 1 have been determined between 1.5 and 305K. Above T{sub C}{sup inter} (x=0.6) and T{sub N}{sup inter} (x=0.8 and 1) up to T{sub N}{sup inter}, these samples exhibit an intralayer antiferromagnetic structure in (001) Mn planes. For x=0.6 sample, the magnetic structure is canted ferromagnetic along the c-axis between T{sub N}{sup inter} and T{sub C}{sup inter} and below T{sub C}{sup Pr}. For the samples with x=0.8 and 1, the magnetic structure is canted antiferromagnetic along the c-axis below T{sub N}{sup inter}. Pr moments order ferromagnetically along the c-axis for the x=0.6 sample below T{sub C}{sup Pr}. The results are summarized in the PrMn{sub 2-x}Fe{sub x}Ge{sub 2} magnetic phase diagram. The general magnetic phase diagram for RMn{sub 2-x}Fe{sub x}Ge{sub 2} (R: La, Ce, Pr, Nd and Sm) is also constructed from previous and present works. For these compounds, the magnetic phase transition from ferromagnetic to antiferromagnetic occurs at different intralayer Mn-Mn distances for each system. These critical distances are larger than the corresponding threshold value d{sub Mn-Mn}{sup a}=2.87A for the ternary end-member RMn{sub 2}X{sub 2} compounds.

  6. Use of Pulsed Nmr Spectroscopy to Measure the Amount of Solid Deposits As a Function of Temperature in Waxy Crudes Utilisation de la spectroscopie RMN pulsée pour mesurer la quantité de dépôts solides en fonction de la température dans les bruts paraffiniques

    Directory of Open Access Journals (Sweden)

    Ruffier-Meray V.

    2006-12-01

    Full Text Available Paraffin crystallization in crude oils and in gas condensates is a major problem for petroleum exploitation. Thermodynamic models are used to evaluate the risk. With them, one calculates the Wax Appearance Temperature (WAT as well as the crystallized fraction as a function of temperature, for temperatures below the WAT. During development, these models are tested against experimental data. Although different methods for measuring the WAT are available in the literature and at petroleum companies, such methods unfortunately do not exist for measuring the crystallized fraction as a function of temperature. In this work, we have developed a low resolution NMR method for measuring the crystallized fraction as a function of temperature. The method was first evaluated using pure samples and was then applied to crude oils. The results were compared to those obtained both from differential calorimetry and from the model. La cristallisation des paraffines dans les pétroles bruts et même dans les gaz à condensat est un problème majeur dans le domaine de l'exploitation pétrolière. Afin d'évaluer ce risque, on utilise des modèles thermodynamiques. Ils permettent de calculer la température de cristallisation commençante (TCC ou Wax Appearance Temperature (WAT ainsi que la fraction cristallisée en fonction de la température (pour des températures inférieures à la TCC. Lors de leur développement, ces modèles doivent être évalués sur des données expérimentales. Il existe dans la littérature et chez les pétroliers différentes méthodes pour mesurer la TCC, malheureusement il n'en est pas de même pour la fraction cristallisée en fonction de la température. Dans cet article, nous avons développé une méthode de RMN basse résolution afin de mesurer la fraction cristallisée en fonction de la température. Elle a d'abord été évaluée sur des mélanges de corps purs puis elle a été appliquée à des pétroles bruts. Les r

  7. Caracterização dos constituintes poliméricos da Maytenus ilicifolia por relaxação nuclear de ¹H por RMN no estado sólido Characterization of Maytenus ilicifolia Samples by ¹H NMR relaxation in the solid state

    Directory of Open Access Journals (Sweden)

    Mônica S. de M. Preto

    2011-01-01

    Full Text Available A Maytenus ilicifolia, conhecida como espinheira-santa, é uma planta popular de uso diverso, como chá é empregada no combate a problemas de doenças gástricas e da diabetes, por exemplo. As plantas possuem em sua constituição polímeros naturais como polissacarídeos, politerpenoides, celulose e fibras. O estudo dos constituintes poliméricos nesse tipo de material tem importância fundamental tanto na identificação, ou seja, qualificação quanto na adulteração da planta. É sabido que podem ser encontrados diversos produtos rotulados como sendo originário da mesma planta, entretanto, muitas das vezes a origem da planta é similar, mas não a mesma, o que pode gerar algum desconforto ou não atividade biológica dos chás quando da ingestão destes. Na literatura não são encontrados muitos trabalhos que envolvam a caracterização comparativa dos constituintes poliméricos, como polissacarídeos e fibras presentes em amostras de origens distintas, para comprovação de adulteração destes produtos. Uma técnica que pode ser promissora para este tipo de estudo é a Ressonância Magnética Nuclear (RMN em estado sólido, já que permite analisar a amostra in natura não sendo um método destrutivo ou invasivo. Esta espectroscopia analisa amostras em campos magnéticos de diferentes potências ou forças. Neste trabalho é apresentado um estudo de caracterização dos constituintes poliméricos majoritários presentes na M. ilicifolia. Três amostras foram estudadas: uma amostra denominada controle e duas comerciais. O estudo envolveu a determinação dos tempos de relaxação spin-rede (T1 do ¹H utilizando a técnica de campo cíclico rápido (FFC, numa gama de frequências que variou de 100 kHz a 10 MHz. Assim, o principal objetivo deste trabalho foi estudar a possibilidade de utilização da RMN de baixo campo magnético na elaboração de um método expedito de análise que permita realizar a caracterização estrutural

  8. UN MODELLO TEORICO PER LA VALORIZZAZIONE DEL PAESAGGIO CULTURALE DELLA DIETA MEDITERRANEA

    Directory of Open Access Journals (Sweden)

    Tiziana Meduri

    2015-12-01

    Full Text Available The study aims to identify guidelines for defining a model of cultural planning oriented to the development of the emerging sector of the territory of Reggio Calabria’s metropolitan city, specifically rural areas, to provide an integrated plan of development of cultural identity. The methodology consisted of a preliminary fact-finding investigation. This has lead to, in theory, an operating model where it is proved that the first action to be performed is the accurate identification of an effective tool that can be applied to the province towed to the emergence and local development: the Mediterranean diet. The second step involved the selection of municipalities able to apply the best practices in the area for the promotion of the Mediterranean Diet. Through a checklist, formulated ad hoc, is checked for quality valorization plans that each municipality must prepare. What you intend to prove is that a careful and participatory cultural program could be the possible way out from the narrow vision of culture as a marginal aspect of economic life and in fact placed in the policies of socio-economic development of the territory.

  9. Sobre el potencial teorico de las representaciones sociales en el campo de la comunicacion

    National Research Council Canada - National Science Library

    Rodriguez Salazar, Tania

    2009-01-01

    En este articulo se desarrollan algunas reflexiones teoricas y metodologicas sobre como la teoria de las representaciones sociales podria ser utilizada en el campo de los estudios sobre comunicacion...

  10. Frontera México-Estados Unidos. Reflexiones para un marco teorico

    Directory of Open Access Journals (Sweden)

    Jorge A. Bustamante

    1991-01-01

    Full Text Available From an perspective inspired in Max Weber´s concepts of social interaction and asymmetries of power, the author leads us through a theoretical reflexion on the specific situation of the borderline regions. He underlines the construction of concepts like extension and intensity of the interaction, degree of internationality , and action and reaction between countries with common borders. His proposal is that the specificity of the relations between Mexico and the US, both micro and macrosocially, can be understood as a complex interaction which starts with (generally economic actions by the US and (generally politicocultural responses by Mexico given her structural incapability of responding in the same way and with the same intensity.

  11. Teorias implicitas del liderazgo, LMX y bienestar laboral: generalizacion de un modelo teorico

    National Research Council Canada - National Science Library

    Nader, Martin; Castro Solano, Alejandro

    2010-01-01

    .... Participaron 1009 personas (440 hombres y 569 mujeres) residentes en cuatro regiones. Se analizo si existian diferencias en la variable valores en el trabajo para confirmar si las regiones eran culturalmente diferentes entre si...

  12. ESTUDIO TEORICO DE TRANSFERENCIAS PROTONICAS EN BASES DE ADN Y EN SISTEMAS MODELO.

    OpenAIRE

    HERRERA PISANI, BARBARA ANDREA

    2005-01-01

    Uno de los objetivos principales de este trabajo de Tesis ha sido caracterizar reacciones de transferencia protónica en sistemas modelo, tales como, el ácido nitrosos y la serie de sus derivados azufrados HXNY (X,Y=O,S) y en sistema de interés biológico c 133p.

  13. Aspectos teoricos sobre la salud como un determinante del crecimiento economico

    OpenAIRE

    Juan Miguel Gallego

    2001-01-01

    Las nuevas teorías del crecimiento económico y los desarrollos en la economía de la salud han planteado, de forma paralela, una relación recíproca entre la salud y el crecimiento. Interrogantes como ¿cuáles son los aportes de la salud al crecimiento económico? son recientes en la agenda de investigación. El reto está en unir estos esfuerzos y construir un cuerpo teórico que incluya a la salud como un determinante del crecimiento. Este documento es una síntesis teórica que muestra los aportes ...

  14. Estudo teorico dos aspectos prosturais e da plasticidade muscular frente ao alongamento

    OpenAIRE

    Fabio Chagas Leoni

    1996-01-01

    Resumo: Este estudo teve como objetivo analisar o comportamento e os processos adaptativos musculares frente ao alongamento. Procurou também, observar quais interferências, esta atividade (o alongamento) teria sobre a postura. A atividade de alongamento foi considerada sob a perspectiva de Lê Boulch (1983), como parte integrante de uma educação fundamental pelo movimento, buscando construir a aresta central da personalidade, constituída pelo Esquema Corporal. Trata-se de uma pesquisa bibliogr...

  15. Um estudo teorico das propriedades estruturais e oticas de derivados de Eumelanina

    OpenAIRE

    Luz Elena Bolivar Marinez

    1997-01-01

    Resumo: Melaninas são uma classe de pigmentos biológicos largamente presentes na natureza dos fungos ao homem. Elas são classificadas em três grandes subclasses: eumelaninas, feomelaninas e alomelaninas. Neste trabalho nós investigamos compostos de eumelanina, o tipo de pigmento mais presente no reino animal em tecidos pigmentados como o cabelo, pele, etc. Acredita-se que a função básica destes pigmentos é a fotoproteção contra a devastação bioquímica produzida pela exposição à radiação so...

  16. ESTUDIO TEORICO DE LA CATALISIS DE ORO EN SUSTRATOS CON SISTEMA ORGANICO PI

    OpenAIRE

    BURGOS CARRASCO, DARWIN ANDRES

    2014-01-01

    En esta tesis se presenta un estudio teórico de la catálisis de especies de oro para adiciones electrofílicas a sustratos con sistemas orgánico pi no aromáticos en alquenos y alquinos. Debido a que el oro presenta una actividad catalítica muy alta en comparación a otros metales de transición, principalmente en el ámbito de la catálisis homogénea, y más aún si se contempla que generalmente se utiliza al mismo precursor químico, el AuCI3, todo esto para reacciones de adición electrofíl...

  17. Sullo statuto teorico dell'offerta di moneta: un dibattito con Augusto Graziani

    OpenAIRE

    cavalieri, duccio

    1996-01-01

    In this article the debate between Prof. Augusto Graziani and the author on the monetary theory of production is carried further on. The main purpose of the paper is to delineate - along Keynesian lines and in opposition to the theory of the credit money circuit - a consistent and realistic view of the nature of the supply of money, general enough to embrace as limit-cases both a strictly endogenous and a strictly exogenous money supply. The interdependence of the supply and demand for money ...

  18. Magnetism instability under pressure in RMn sub 2 compounds

    Energy Technology Data Exchange (ETDEWEB)

    Voiron, J.; Ballou, R.; Deportes, J.; Galera, R.M.; Lelievre, E. (Laboratoire Louis Neel, C.N.R.S., 166 X, 38042 Grenoble Cedex, France (FR))

    1991-04-15

    Magnetic properties of the Nd-, Gd-, Y-, TbMn{sub 2} intermetallic cubic Laves phases have been studied under applied pressure. Large effects of pressure are observed on the ordering temperatures and on the magnetization curves. In all cases the ordering temperatures decrease and the Mn magnetic moment tends to be suppressed with increasing pressure. Results confirm the existence of a critical distance between Mn atoms, for the appearance of a Mn magnetic moment.

  19. Magnetism of manganese in RMn sub 2 and RMn sub 4 Al sub 8 (R=Y, Gd, Er) intermetallics

    CERN Document Server

    Talik, E; Winiarski, A; Neumann, M; Mydlarz, T; Gilewski, A; Böhm, H

    1998-01-01

    The XPS electronic structure was measured for YMn sub 2 , GdMn sub 2 , ErMn sub 2 , YMn sub 4 Al sub 8 and GdMn sub 4 Al sub 8 single crystals and pure Mn. Exchange splitting of Mn 3d and 3s states was found for the compounds with magnetic manganese. The electrical resistivity of the GdMn sub 2 single crystal shows an antiferromagnetic transition at 108 K and the second transition at 32 K. The lattice parameter against temperature of GdMn sub 2 exhibits a large spontaneous magnetostriction at T sub N. The anisotropic character of the GdMn sub 2 magnetization was found. The results were discussed using the Yamada and Shimizu model. (author)

  20. Analisis del rendimiento y consumo de programas orientados al calculo

    OpenAIRE

    Ruiz Ramírez, Marcos

    2016-01-01

    Estudio que pretende crear una implementación de computación paralela/vectorial a las funciones y rutinas de cálculo del primer nivel del BLAS, recogida en una librería (estática o dinámica), analizando su impacto energético.

  1. Sobre o calculo diferencial paraconsistente de da Costa

    OpenAIRE

    2004-01-01

    Resumo: O objetivo deste trabalho é desenvolver alguns principios básicos de um Cálculo Diferencw Paraconsistente. Como elementos motivadores para isso, apresentamos, na Introdução, alguns dados sobre o desenvolVuI1ento do cálculo diferencial, desde suas origens ao advento da anãlise não-standard, bem como relativos à história da lógica e à da teoria de conjuntos, focalizando os sistemas lógicos paraconsistentes e as teorias paraconsistentes de conjuntos. Apresentamos, no Capítulo 1, propried...

  2. Calculo diferencial en funciones de una variable para la universalizacion

    OpenAIRE

    Sabín Rendón, Yolanda; Toledo Dieppa, Vilma; Albelo Martínez, Mercedes Caridad; Pino Roque, José Antonio; García Gutiérrez, Lázaro

    2005-01-01

    La Tarea Álvaro Reinoso de la Universalización enfrenta en múltiples ocasiones escasez de bibliografía básica, por lo que un grupo de profesores de la Universidad Agraria de La Habana, elaboró un libro electrónico, para el trabajo con el tema “Cálculo Diferencial en Funciones de una Variable”. Aparecen desarrollados ejemplos que ilustran algoritmos de trabajo en las temáticas abordadas y se concibe un grupo de ejercicios para ser resueltos de manera independiente. Este material tiene la venta...

  3. Analisis del rendimiento y consumo de programas orientados al calculo

    OpenAIRE

    Ruiz Ramírez, Marcos

    2016-01-01

    Estudio que pretende crear una implementación de computación paralela/vectorial a las funciones y rutinas de cálculo del primer nivel del BLAS, recogida en una librería (estática o dinámica), analizando su impacto energético.

  4. Dosimetry in intravascular brachytherapy; Calculos dosimetricos em braquiterapia intravascular

    Energy Technology Data Exchange (ETDEWEB)

    Campos, Laelia Pumilla Botelho

    2000-03-01

    Among the cardiovascular diseases responsible for deaths in the adult population in almost all countries of the world, the most common is acute myocardial infarction, which generally occurs because of the occlusion of one or more coronary arteries. Several diagnostic techniques and therapies are being tested for the treatment of coronary artery disease. Balloon angioplasty has been a popular treatment which is less invasive than traditional surgeries involving revascularization of the myocardium, thus promising a better quality of life for patients. Unfortunately, the rate of restenosis (re-closing of the vessel) after balloon angioplasty is high (approximately 30-50% within the first year after treatment).Recently, the idea of delivering high radiation doses to coronary arteries to avoid or delay restenosis has been suggested. Known as intravascular brachytherapy, the technique has been used with several radiation sources, and researchers have obtained success in decreasing the rate of restenosis in some patient populations. In order to study the radiation dosimetry in the patient and radiological protection for the attending staff for this therapy, radiation dose distributions for monoenergetic electrons and photons (at nine discrete energies) were calculated for blood vessels of diameter 0.15, o,30 and 0.45 cm with balloon and wire sources using the radiation transport code MCNP4B. Specific calculations were carried out for several candidate radionuclides as well. Two s tent sources (metallic prosthesis that put inside of patient's artery through angioplasty) employing {sup 32} P are also simulated. Advantages and disadvantages of the various radionuclides and source geometries are discussed. The dosimetry developed here will aid in the realization of the benefits obtained in patients for this promising new technology. (author)

  5. Estimation of hydraulic conductivity on clay content in soil determined from resistivity data

    Energy Technology Data Exchange (ETDEWEB)

    Shevnin, Vladimir; Delgado-Rodriguez, Omar; Mousatov, Aleksandr [Mexican Petroleum Institute, Mexico, D.F. (Mexico); Ryjov, Albert [Moscow State Geological Prospecting Academy, Geophysical Faculty, Moscow (Russian Federation)

    2006-07-15

    The influence of clay content in sandy and clayey soils on hydraulic conductivity (filtration coefficient) is considered. A review of published experimental data on the relationship of hydraulic conductivity with soil lithology and grain size, as dependent on clay content is presented. Theoretical calculations include clay content. Experimental and calculated data agree, and several approximation formulas for filtration coefficient vs clay content are presented. Clay content in soil is estimated from electric resistivity data obtained from 2D VES interpretation. A two-step method is proposed, the first step including clay content calculating from soil resistivity and groundwater salinity, and the second step including filtration coefficient estimating from clay content. Two applications are presented. [Spanish] El contenido de arcilla en suelos areno-arcillosos influye sobre la permeabilidad hidraulica (coeficiente de filtracion). Se presenta una revision de datos experimentales publicados que relacionan el coeficiente de filtracion con el tipo litologico del suelo y el tamano de las particulas. A partir de calculos teoricos, se modifican las conocidas formulas que relacionan el coeficiente de filtracion con el contenido de arcilla. Se estima el contenido de arcilla a partir de los datos interpretados por el metodo SEV, y se propone un procedimiento para la estimacion del coeficiente de filtracion: (a) calculo del contenido de arcilla a partir de la resistividad del suelo y de la salinidad del agua subterranea, (b) estimacion del coeficiente de filtracion a partir del contenido de arcilla. Se presentan algunos ejemplos de la aplicacion de esta metodologia.

  6. ESTUDIO TEORICO DE LA ESTRUCTURA ELECTRONICA Y DE LOS MECANISMOS DE TAUTOMERIA LACTAMA-LACTIMA EN BILINAS DE FITOCROMO

    OpenAIRE

    MATUTE MORALES, RICARDO ANDRES

    2010-01-01

    El fitocromo es un fotoreceptor de plantas que también se encuentra en bacterias y hongos. En plantas, el fitocromo regula respuestas fotomorfogénicas de la planta como, por ejemplo, el desarrollo y crecimiento del tallo, regulación en el periodo de dormancia y de germinación de las semillas, floración, fototaxis, mecanismos de evasión de la sombra, etc. Todos ellos activados o desactivados en forma diferencial mediante longitudes de onda específicas en la región UV-Visible del espectro...

  7. Teorizando acerca del Conocimiento Productivo para Entender la Educacion Teorico Profesional (Theorizing about Productive Knowledge To Understand Professional Technical Education).

    Science.gov (United States)

    Hidalgo, Abelardo Castro; Carrasco, Decler Martinez

    2000-01-01

    States that, internationally, Professional Technical Education emerges as a method of providing educational solutions for poor sectors of the population. Cites University of Chalmer (Sweden) and University of Bio-Bio (Chile) as institutions transformed into technological universities. Discusses what is productive knowledge and conditions under…

  8. Enfoques teoricos y estrategias metodologicas en la investigacion empirica de audiencias televisivas en America Latina: 1992-2007

    National Research Council Canada - National Science Library

    Lozano, Jose Carlos; Frankenberg, Lorena

    2008-01-01

    El articulo reporta los avances de una revision documental de estudios empiricos de audiencias de television realizados en America Latina y publicados entre 1992 y 2007 en las principales revistas cientificas del campo...

  9. ESTUDIO TEORICO DE SELECTIVIDAD ANIONICA Y MECANISMO DE APERTURA Y CIERRE (GATING) EN CANALES DE CLORURO DE LA FAMILIA CLC.

    OpenAIRE

    BRIONES JARA, RODOLFO CESAR

    2006-01-01

    CIC es una familia de proteínas de membrana que transportan cloruros y desempeñan funciones como canales de cloruro o intercambiadores protón/cloruro. Estas proteínas, conservadas desde bacterias a humanos, son importantes para la fisiología celular y est 115p.

  10. FILOSOFIA DE LA MENTE; APORTES TEORICOS Y EXPERIMENTALES A LA VISIÓN EMERGENTISTA DEL VINCULO MENTE-CEREBRO.

    Directory of Open Access Journals (Sweden)

    Paul Ruiz Santos

    2011-01-01

    Full Text Available El presente trabajo intenta sumar alprograma emergentista dentro del mapa teórico referido a la Filosofía de la Mente, tomando como referentes a disciplinas y teorías naturalizadas. Algunos puentes vinculantes desde la naturalización pueden ser por ejemplo el neuro-psicoanálisis, las neuronas espejo, la psicosomática, entre otros. Dichos puentes son posibles de ser tendidos a través de la naturalización de los procesos psicológicos vinculándolos a diferentes procesos biológicos. El objetivo del trabajo no pretende obturar los procesos psicológicos a través de la simplificación y reduccionismo de los mismos, ni biologizar la psicología a través de planteos cartesianos. Sino, de la mano de la neuro-fenomenología, acceder a más y nuevas evidencias sobre el vínculo mente-cerebro y sus implicancias aportando a una visión interaccionista y emergentista del vínculo.

  11. Los conflictos ambientales en Cuba, solucion dentro del derecho interno. Su tratamiento teorico doctrinal en otros sistemas de derecho comparado

    National Research Council Canada - National Science Library

    Antunez Sanchez, Alcides Francisco; Bruzon Viltres, Carlos Justo

    2012-01-01

    ...; el problema cientifico se enfoca en demostrar la inaccion por parte de los entes y agentes que con jurisdiccion y competencia estan facultados para aplicar la legislacion en materia de medio ambiente...

  12. ESTUDIO TEORICO EXPERIMENTAL DEL FENOMENO DE MIGRACION ESPECIFICA EN MATERIALES POLIMERICOS UTILIZADOS EN EL ENVASADO DE ALIMENTOS

    OpenAIRE

    TORRES MEDIANO; ALEJANDRA

    2011-01-01

    El proceso de transferencia de masa de componentes desde los envases hacia los alimentos determina la calidad sensorial y el grado de inocuidad del producto envasado. El presente estudio está enfocado a un análisis teórico-experimental del fenómeno de migración específica, utilizando diferentes tipos de simulantes de alimentos, considerando además el efecto de la concentración de migrante, el espesor de los films plásticos y la temperatura. La metodología del estudio comprende anális...

  13. Fundamentos teoricos de la creacion de un modelo de adquisicion corporativa internacional: Caso de las principales empresas de Nuevo Leon

    Directory of Open Access Journals (Sweden)

    Cabeza, L.

    2008-07-01

    Full Text Available The importance to propose a success Model in the international corporate acquisitions consists of offering to the important Mexican firms the factors that will allow having greater success with the international investments. In this research we selected four of the most important firms of Nuevo Leon that have important experience with international acquisitions and present them the questionnaire that was designed to validate the variables of the Model. In this paper we present the theories that give the theoretical foundations to the variables of the proposed Model that consist of 6 variables or key success factors that need to be considered for an international acquisitions, which are: Country Knowledge, Industry Knowledge, Customer relationship, Supplier relationship, Technology and Market.

  14. Constructos teoricos para abordar, de un modo investigativo, problemas entre marketing, produccion y logistica en las empresas colombianas

    National Research Council Canada - National Science Library

    Varon Sandoval, Alexander

    2013-01-01

    .... La poblacion objeto de estudio estuvo representada por los colaboradores de los departamentos de marketing, produccion y logistica, de algunas empresas de manufactura en Colombia indistintamente...

  15. Las multiples violencias de la "violencia" en la escuela: desarrollo de un enfoque teorico y metodologico integrativo

    Directory of Open Access Journals (Sweden)

    María Inés Bringiotti

    2004-12-01

    Full Text Available Foram investigados diversos tipos de violência, no âmbito escolar, que ocasionam aumento do risco para a ocorrência de maltrato infantil. Na primeira etapa a amostra ficou composta por quatro escolas de Buenos Aires, duas de educação inicial e duas primárias, selecionadas ao acaso, em dois distritos predominantemente com classes sociais diferentes (média e baixa. Foram encontradas correlações entre o potencial de maltrato, a História da Educação, nível sócio econômico e educacional da mãe, problemas comportamentais e emocionais da criança. Mediante a análise de regressão foram obtidos modelos específicos para os dois grupos da amostra e encontrados aspectos de violência social, institucional e na interação com os pares (infantil. Na segunda etapa foram encontradas correlações entre o potencial de maltrato, depressão, apoio social. Foram implementados programas de intervenção para pais e, para docentes e autoridades de um jardim da infância, analisando as variáveis de cambio e as que resistiram a uma modificação.

  16. Marxismo como referencial teorico-metodologico em saude coletiva: implicacoes para a revisao sistematica e sintese de evidencias

    Directory of Open Access Journals (Sweden)

    Cassia Baldini Soares

    2013-12-01

    Full Text Available O objeto deste estudo é a incorporação em revisões sistemáticas de resultados de pesquisas desenvolvidas na vertente marxista de produção do conhecimento, como evidências em saúde. Os objetivos são: rever os pressupostos do materialismo histórico e dialético (MHD e discutir as implicações da dialética para a revisão da literatura e síntese de evidências. O MHD constitui um referencial potente para geração de conhecimento e transformação das políticas e práticas em saúde, a partir da explicação de que as contradições sociais estão na base do processo saúde-doença, construção teórica fundamental no campo da saúde coletiva. Atualmente observa-se considerável influência do paradigma crítico, de origem marxista, na construção do conhecimento em saúde. Pesquisas no paradigma crítico apresentam métodos complexos de apreensão do objeto, inerentes às diretrizes da dialética, oferecendo resultados que constituem evidências em saúde. Revisões sistemáticas devem enfrentar a dificuldade metodológica de integrar esses resultados plenamente ao cuidado em saúde.

  17. Theoretical study of excitonic complexes in semiconductors quantum wells; Estudo teorico de complexos excitonicos em pocos quanticos de semicondutores

    Energy Technology Data Exchange (ETDEWEB)

    Dacal, Luis Carlos Ogando

    2001-08-01

    A physical system where indistinguishable particles interact with each other creates the possibility of studying correlation and exchange effect. The simplest system is that one with only two indistinguishable particles. In condensed matter physics, these complexes are represented by charged excitons, donors and acceptors. In quantum wells, the valence band is not parabolic, therefore, the negatively charged excitons and donors are theoretically described in a simpler way. Despite the fact that the stability of charged excitons (trions) is known since the late 50s, the first experimental observation occurred only at the early 90s in quantum well samples, where their binding energies are one order of magnitude larger due to the one dimensional carriers confinement. After this, these complexes became the subject of an intense research because the intrinsic screening of electrical interactions in semiconductor materials allows that magnetic fields that are usual in laboratories have strong effects on the trion binding energy. Another rich possibility is the study of trions as an intermediate state between the neutral exciton and the Fermi edge singularity when the excess of doping carriers is increased. In this thesis, we present a theoretical study of charged excitons and negatively charged donors in GaAs/Al{sub 0.3}Ga{sub 0.7}As quantum wells considering the effects of external electric and magnetic fields. We use a simple, accurate and physically clear method to describe these systems in contrast with the few and complex treatments s available in the literature. Our results show that the QW interface defects have an important role in the trion dynamics. This is in agreement with some experimental works, but it disagrees with other ones. (author)

  18. Teorizando acerca del Conocimiento Productivo para Entender la Educacion Teorico Profesional (Theorizing about Productive Knowledge To Understand Professional Technical Education).

    Science.gov (United States)

    Hidalgo, Abelardo Castro; Carrasco, Decler Martinez

    2000-01-01

    States that, internationally, Professional Technical Education emerges as a method of providing educational solutions for poor sectors of the population. Cites University of Chalmer (Sweden) and University of Bio-Bio (Chile) as institutions transformed into technological universities. Discusses what is productive knowledge and conditions under…

  19. A teorico-analitica array for policy studies: the case of the education and training of political cadres in Argentina

    OpenAIRE

    2015-01-01

    This paper describes the methodological process by which an analytical matrix for the study of political rank and file in democracy training policies was built, implemented by the Argentine State. The study covers the successive periods of Government 1994-2011, through which it seeks to identify and analyze what have been State policies formulated and implemented from the sanction of article 38 of the Constitution, which recognizes the political parties as central institutions of the democrat...

  20. A teorico-analitica array for policy studies: the case of the education and training of political cadres in Argentina

    Directory of Open Access Journals (Sweden)

    María Melina Guardamagna Pesciullesi

    2015-08-01

    Full Text Available This paper describes the methodological process by which an analytical matrix for the study of political rank and file in democracy training policies was built, implemented by the Argentine State. The study covers the successive periods of Government 1994-2011, through which it seeks to identify and analyze what have been State policies formulated and implemented from the sanction of article 38 of the Constitution, which recognizes the political parties as central institutions of the democratic system. The Matrix allowed to collect and systematize the existing documentation and analyze and interpret the process of formulation and implementation of these policies. The study concludes that in the case of Argentina repeated successive confusion between the roles and needs of the State with those of Government, that has prevented the stabilisation of a model of education and political training as prescribed by the constitutional mandate.

  1. Creation and design of a test for the Evaluation of Upper Limb Apraxia (EULA) based on a cognitive model: a pilot study.

    Science.gov (United States)

    Perez-Marmol, José Manuel; Lopez-Alcalde, Samuel; Carnero-Pardo, Cristóbal; Canadas-De la Fuente, Guillermo A; Peralta-Ramirez, M Isabel; Garcia-Rios, M Carmen

    2015-01-16

    Introduccion. La apraxia es un trastorno neurologico caracterizado por la dificultad en la ejecucion de habilidades gestuales aprendidas a pesar de tener preservados los sistemas motores y sensoriales, la coordinacion y la comprension, asi como de una adecuada colaboracion. Actualmente, existen pocas herramientas validadas que evaluen este sindrome de manera global. En el presente estudio, se ha creado y diseñado un test para la evaluacion de la apraxia de los miembros superiores (EULA), basado en modelos teoricos. Sujetos y metodos. Se selecciono una poblacion de 57 pacientes con quejas subjetivas de deterioro cognitivo y 39 personas sin quejas ni deterioro cognitivo, a las cuales se les administro el test EULA, entre otros tests. Se realizo un analisis factorial de componentes principales y un calculo tanto de la fiabilidad como de la validez de dicho instrumento. Resultados. El analisis factorial agrupo en nueve factores todos los items de la prueba, con una varianza total explicada del 69,91%. El test ha mostrado una alta fiabilidad, con un alfa de Cronbach de 0,929 y un coeficiente de Guttman de 0,870 con el metodo de las dos mitades. El test tambien mostro tener una adecuada validez de constructo, al existir correlacion significativa entre seis factores del test y dos subtests de apraxia. Conclusiones. El test EULA, surgido de las propuestas de evaluacion a nivel teorico desarrolladas por diferentes autores, muestra una puntuacion superior en personas sanas respecto a personas con manifestaciones subjetivas de deterioro cognitivo, ademas de tener una alta fiabilidad y validez de constructo.

  2. Conceptuaciones de los estudiantes de las facultades de educacion y ciencias naturales de la Universidad de Puerto Rico, recinto de Rio Piedras, acerca de la ciencia y la pseudociencia

    Science.gov (United States)

    Reyes Medina, Hector A.

    Esta investigacion describe las conceptuaciones de los estudiantes de tercer ano o mas a nivel de bachillerato de los programas de Educacion en Ciencia y Ciencias Naturales de la Universidad de Puerto Rico, Recinto de Rio Piedras, acerca de lo establecido en la literatura para distinguir el conocimiento cientifico de las creencias pseudocientificas. Este estudio se guio por un diseno tipo encuesta transversal que permitio conocer de manera consistente las conceptuaciones de los estudiantes encuestados acerca de la Ciencia y la Pseudociencia. Ademas, permitio desarrollar inferencias estadisticas relacionadas a la poblacion de estudio, sus conceptuaciones y su inclinacion teorica en torno al Realismo y al Racionalismo cientifico moderados. El instrumento utilizado fue el Cuestionario acerca de las concepciones de la ciencia y la pseudocienca en estudiantes universitarios, Reyes (2015). Este cuestionario fue validado mediante la recopilacion de diversas fuentes de evidencias, entre estas se encuentran las evidencias basadas en el contenido, el proceso de respuesta, la estructura interna y de constructo. Tambien, se calculo el Alfa de Crombach para la escala total y para cada componente y se realizo un analisis de factores que demostro la presencia de seis componentes claramente definidos de acuerdo a lo esperado sobre las caracteristicas originales del instrumento. Las estadisticas utilizadas fueron descriptivas. Participaron 302 alumnos, de las facultades de educacion y ciencias naturales. Se encontro que las conceptuaciones de los estudiantes de ambas facultades se inclinan en un 66.2% a favor con lo establecido en el modelo teorico en torno al Realismo y al Racionalismo cientifico moderados. Sin embargo, aun hay un 33.8% de los estudiantes de ambas facultades que poseen conceptuaciones distintas al modelo teorico propuesto.

  3. N.M.R. study of organo-phosphorus compounds: non equivalence of methylenic protons in the {alpha} position of an asymmetric phosphorus atom. Application to study of coupling constants J{sub P,H} and J{sub H,H}; R.M.N. de composes organo-phosphores: non equivalence de protons methyleniques en {alpha} d'un phosphore asymetrique. Application a l'etude des constantes de couplage J{sub P,H} et J{sub H,H}

    Energy Technology Data Exchange (ETDEWEB)

    Albrand, J.P. [Commissariat a l' Energie Atomique, Grenoble (France). Centre d' Etudes Nucleaires

    1969-07-01

    Non-equivalent methylenic protons, with respect to an asymmetric center, have been observed in the n.m.r. spectra of some three- and tetra-coordinated phosphorus compounds. The analysis of these spectra yield the following results: in the studied secondary phosphines, the inversion rate at the phosphorus atom is slow on the n.m.r. time scale; the geminal coupling constant, for a free-rotating methylene group attached to a phosphorus atom, is negative; in phosphines the non equivalence of methylenic protons reveals two {sup 2}J{sub P-C-H} coupling constants which differ by about 5 Hz. This result is in agreement with previous studies on cyclic phosphines. In phosphine oxides, the {sup 2}J{sub P-C-H} values are negative. The {sup 3}J{sub H-P-C-H} coupling constant is positive in both phosphines and phosphine oxides. In phosphines, the non-equivalent methylenic protons exhibit two nearly equal values for this coupling constant. (author) [French] La non-equivalence de protons methyleniques observee dans quelques composes phosphores tricoordines et tetracoordines a apporte les resultats suivants, concernant la stereochimie et les constantes de couplage dans ces composes: dans les phosphines secondaires, la structure pyramidale des liaisons issues du phosphore est fixe a l'echelle de temps de mesure de la R.M.N.; la constante de couplage {sup 2}J{sub H-C-H}, pour un methylene en libre rotation en {alpha} d'un atome de phosphore, est negative; dans les phosphines etudiees, la non-equivalence. observee pour les protons methyleniques s'accompagne d'une difference importante (5 Hz) entre les deux constantes de couplage {sup 2}J{sub P-C-H} determinees par l'analyse; ce resultat est en accord avec la stereospecificite deja observee pour ce couplage dans les phosphines cycliques. Les valeurs observees pour {sup 2}J{sub P-C-H} dans les oxydes de phosphines sont negatives. Les valeurs de la constante de couplage {sup 3}J{sub H-P-C-H}, dans les phosphines

  4. Contribution to the study of the {sup 31}P, {sup 1}H spin spin coupling constant N. M. R. in three co-ordinated phosphorus compounds. Influence of the bond orientation and of the nature of the substituent around the phosphorus atom; Contribution a l'etude des constantes de couplage {sup 31}P, {sup 1}H en R.M.N. dans les composes organo-phosphores tricoordines. Influence des facteurs geometriques et de la nature des substituants au niveau du phosphore

    Energy Technology Data Exchange (ETDEWEB)

    Robert, J.B. [Commissariat a l' Energie Atomique, Grenoble (France). Centre d' Etudes Nucleaires

    1969-07-01

    substituants au niveau du phosphore. Les constantes de couplage sont du type {sup 3}J{sub PH} au travers des fragments P-C-C-H et P-O-C-H, et {sup 2}J{sub PH} au travers du fragment P-CH. Les resultats montrent que, pour les temps d'observation de la RMN, la disposition des liaisons au niveau du phosphore dans l'ensemble des composes etudies (dioxaphospholanes-1,3,2, dioxaphosphorinanes-1,3,2, phosphacyclopentenes-3, phosphorinanones-4) qui portent des substituants varies au niveau du phosphore, est pyramidale et fixe. Ce resultat s'applique egalement aux phosphines secondaires. Le couplage depend tres peu des substituants fixes sur le phosphore sauf dans le cas d'un azote. Pour les couplages {sup 3}J, les resultats montrent que la dependance attendue, basee uniquement sur l'angle diedre de type ''Karplus'', ne suffit pas. La direction du doublet libre donne lieu a une variation supplementaire sur J. Dans le cas des couplages {sup 2}J{sub P-C-H} cette influence est le facteur principal, les variations de J allant de + 25 cps a -6 cps: les valeurs peuvent etre traduites par une loi J = f({alpha}) (0 {<=} {alpha} {<=} 180) {alpha} etant l'angle diedre des plans H-C-P et C-P-X, X representant la direction du doublet libre (axe ternaire de la pyramide passant par le phosphore). (auteur)

  5. The chemical equilibrium under non-ideal conditions: industrial applications; El equilibrio quimico bajo condiciones no ideales: aplicaciones industriales

    Energy Technology Data Exchange (ETDEWEB)

    Silva Martinez, Susana; Alvarez Gallegos, Alberto; Quere, Alain [Instituto de Investigaciones Electricas, Cuernavaca (Mexico)

    1993-05-01

    In this paper is described the application of a computer program to the chemical equilibrium in non-ideal conditions (aqueous solutions of multicomponent electrolytes in the ionic forces interval: 0 < 1 < 6 mol/Kg H{sub 2}O and temperatures close to 25 celsius degrees), and its importance at industrial scale. The calculation of the thermodynamic properties of the solution (activity coefficients, osmotic coefficient, and water activity) is based in one of the most modern theories of the electrolytes; the theoretical results, compared with the experimental ones have an error of 10% or better. [Espanol] En este trabajo se describe la aplicacion de un programa de computo al equilibrio quimico en condiciones no ideales (soluciones acuosas de electrolitos multicomponentes en el intervalo de fuerzas ionicas: 0 < 1 < 6 mol/Kg H{sub 2}O y temperaturas cercanas a 25 grados celsius) y su importancia a escala industrial. El calculo de las propiedades termodinamicas (coeficientes de actividad, coeficiente osmotico y actividad del agua) de la solucion, esta basado en una de las teorias mas modernas de los electrolitos; los resultados teoricos comparados con los experimentales tienen un error del 10% o mejor.

  6. Power factor correction at the Miguel Hidalgo refinery; Correccion del factor de potencia en la refineria Miguel Hidalgo

    Energy Technology Data Exchange (ETDEWEB)

    Dominguez Gonzalez, Gustavo [Petroleos Mexicanos, Refineria Miguel Hidalgo, Tula de Allende (Mexico)

    1992-12-31

    In this paper the theoretical fundament and formulae of the power factor are analyzed and a relationship among kilowatts, kilovars and power factor, is shown; also it deals with power factor in combination with load groups, as well as the numerical calculation of the required kvar for the desired improvement of the power factor. Additionally the technical and economical aspects of the capacitors and synchronous motors are contemplated, as well as their location in the electric system in order to achieve the maximum benefits. Finally, the savings obtained with the installation of capacitors in the electric power system of the Miguel Hidalgo refinery, are explained. [Espanol] En el presente trabajo se analizan los fundamentos teoricos y formulas del factor de potencia y se muestra la relacion entre kilowatts, kilovars y factor de potencia; tambien trata al factor de potencia combinado de grupos de cargas, asi como el calculo numerico de los KVAR necesarios para la mejora deseada del factor de potencia. Ademas se contemplan aspectos tecnicos y economicos de los capacitores y los motores sincronos, asi como la ubicacion de los mismos en el sistema electrico para lograr los maximos beneficios. Finalmente se explican las ganancias economicas que se obtuvieron al instalarse capacitores en el sistema electrico de potencia de la refineria Miguel Hidalgo.

  7. Pressure induced magneto-structural phase transitions in layered RMn2X2 compounds (invited)

    Science.gov (United States)

    Kennedy, Shane; Wang, Jianli; Campbell, Stewart; Hofmann, Michael; Dou, Shixue

    2014-05-01

    We have studied a range of pseudo-ternaries derived from the parent compound PrMn2Ge2, substituting for each constituent element with a smaller one to contract the lattice. This enables us to observe the magneto-elastic transitions that occur as the Mn-Mn nearest neighbour distance is reduced and to assess the role of Pr on the magnetism. Here, we report on the PrMn2Ge2-xSix, Pr1-xYxMn2Ge2, and PrMn2-xFexGe2 systems. The pressure produced by chemical substitution in these pseudo-ternaries is inherently non-uniform, with local pressure variations dependent on the local atomic distribution. We find that concentrated chemical substitution on the R or X site (e.g., in Pr0.5Y0.5Mn2Ge2 and PrMn2Ge0.8Si1.2) can produce a separation into two distinct magnetic phases, canted ferromagnetic and canted antiferromagnetic, with a commensurate phase gap in the crystalline lattice. This phase gap is a consequence of the combination of phase separation and spontaneous magnetostriction, which is positive on transition to the canted ferromagnetic phase and negative on transition to the canted antiferromagnetic phase. Our results show that co-existence of canted ferromagnetic and antiferromagnetic phases depends on chemical pressure from the rare earth and metalloid sites, on local lattice strain distributions and on applied magnetic field. We demonstrate that the effects of chemical pressure bear close resemblance to those of mechanical pressure on the parent compound.

  8. Magnetoelectric and antiferromagnetic photogalvanic effects in RMn2O5 oxides: A symmetric approach

    Science.gov (United States)

    Men'shenin, V. V.

    2012-10-01

    Possible magnetic states of the commensurate antiferromagnetic manganate phase with a nonzero wave vector of the structure have been analyzed within the group-theoretical approach using only the space symmetry group. A phenomenological description of the magnetoelectric effect has been performed and the possibility of the existence of the antiferromagnetic photogalvanic effect in this phase has been established using the magnetic states obtained in this study.

  9. Phonon excitations and magnetoelectric coupling in multiferroic RMn2O5

    Science.gov (United States)

    Golrokh Bahoosh, Safa; Wesselinowa, Julia M.; Trimper, Steffen

    2013-05-01

    Multiferroic rare-earth manganites are theoretically studied by focusing on the coupling to the lattice degrees of freedom. We demonstrate analytically that the phonon excitations in the multiferroic phase are strongly affected by the magnetoelectric coupling, the spin-phonon interaction and the anharmonic phonon-phonon interaction. Based on a microscopic model, the temperature dependence of the phonon dispersion relation is analyzed. It offers an anomaly at both the ferroelectric and the magnetic transition indicating the mutual coupling between multiferroic orders and lattice distortions. Depending on the sign of the spin-phonon coupling the phonon modes become softer or harder in accordance with experimental observations. We show that the phonon spectrum can be also controlled by an external magnetic field. The phonon energy is enhanced by increasing that field. The applied Green's function technique allows the calculation of the macroscopic magnetization depending on both the phonon-phonon and the spin-phonon couplings.

  10. Interrelation between electronic structure and interatomic distances for RMn2X2 compounds

    Science.gov (United States)

    Gerasimov, E. G.; Kanomata, T.; Gaviko, V. S.

    2007-03-01

    The heat capacity was studied for LaMn2Si2, La0.75Y0.25Mn2Si2, La0.7Y0.3Mn2Si2, YMn2Si2 and LaFe2Si2 isostructural intermetallic compounds in the temperature range 1.8-360 K. The electronic, magnetic and lattice contributions to the heat capacity of the compounds were determined and analyzed. The interrelation was found between values of the electronic contribution to the heat capacity (density of states at the Fermi level) and crystal lattice parameters of R(Mn,Fe,Ni)2Si2 compounds. The electronic contribution and the density of states at Fermi level increase with increasing lattice parameters of the compounds. The change of interlayer Mn-Mn exchange interactions with change of Y concentration in La1-xYxMn2Si2 compounds is not accompanied by considerable changes in the electronic contribution to the heat capacity and density of states at the Fermi level. The performed analysis of the magnetic contribution shows that no essential differences exist between the behavior of the heat capacity of the compounds with d⩾dc and with d

  11. NMR study of Corynebacterium melassecola metabolism; Etude du metabolisme de corynebacterium melassecola par RMN

    Energy Technology Data Exchange (ETDEWEB)

    Rollin, C.; Morgant, V.; Guyonvarch, A. [Centre ORSAN, 91 - Les Ulis (France); Guerquin Kern, J.L. [Institut Curie, 91 - Orsay (France)

    1994-12-31

    Corynebacterium melassecola is a microorganism producing glutamic acid, an aminate acid used as food additive. Knowledge of its metabolism is essential for improving the phyla. A study is carried out on intracellular extracts with NMR spectrometry in order to determine certain glucose catabolism pathways using a partial isotopic enrichment with (1-{sup 13}C) or (6-{sup 13}C) glucose. Results demonstrate the particular metabolism of Corynebacteria. 2 tabs., 3 refs.

  12. Analysis of goyazensolide, in solution, by NMR; Analise do goiazensolideo, em solucao, por RMN

    Energy Technology Data Exchange (ETDEWEB)

    Perry, Katia S.P.; Boaventura, Maria Amelia D. [Minas Gerais Univ., Belo Horizonte, MG (Brazil). Dept. de Quimica; Oliveira, Alaide B. de [Minas Gerais Univ., Belo Horizonte, MG (Brazil). Dept. de Produtos Farmaceuticos; Silva, Eduardo M.B. da; Silva, Antonio Jorge R. da [Universidade Federal, Rio de Janeiro, RJ (Brazil). Nucleo de Pesquisas de Produtos Naturais

    1995-12-31

    The identification and characterization of goyazensolide, a sesquiterpenic lactone, from Lychnophora passerina, was made based on comparative study of its spectral data. The methods used in this work include {sup 1} H and {sup 13} C NMR besides IR and UV spectroscopies. Data on chemical shifts as well as coupling constants were presented and analysed, furthermore the results were discussed 3 refs., 1 fig., 2 tabs.

  13. Temperature Dependent Properties of Perovskite Small R-Ion RMnO3 Systems

    Science.gov (United States)

    Chen, Haiyan; Yu, Tian; Gao, Peng; Tyson, Trevor; Ahn, Keun Hyuk

    2013-03-01

    Perovskite small ion E-type systems with radii smaller than that of Lu have been synthesized. The structure, heat capacity and magnetic measurements have been used to compare them with standard E-type systems such as LuMnO3 and HoMnO3. Analysis of the structure is combined with theoretical estimates to relate the electronically driven polarization with the atomic structure. This work is supported by DOE Grant DE-FG02-07ER46402.

  14. Direct observation of interlocked domain walls in hexagonal RMnO3 (R=Tm, Lu)

    Science.gov (United States)

    Zhang, Q. H.; Wang, L. J.; Wei, X. K.; Yu, R. C.; Gu, L.; Hirata, A.; Chen, M. W.; Jin, C. Q.; Yao, Y.; Wang, Y. G.; Duan, X. F.

    2012-01-01

    Using state-of-the-art aberration-corrected annular-bright-field and high-angle annular-dark-field scanning transmission electron microscopy, we investigated domain wall structures in multiferroic hexagonal TmMnO3 and LuMnO3 ceramics at the atomic scale. Two types of 180° domain walls (DWs), i.e., the transverse and the longitudinal DWs with uniform displacements of a/3 and 2a/3, respectively, were identified along the b direction, which is in agreement with the interlock between the ferroelectric and structural translation domain walls that had been predicted previously. Across the domain wall the arrangement of MnO5 polyhedra was not found to be inversed, indicating that (i) it has negligible effects on the polarization and (ii) the structures of the neighbor domains with opposite polarizations are not exactly the same. These wall structures are different from the polarization inversion in conventional ferroelectrics and may be used to explain the unusual transport properties and magnetoelectic effects.

  15. Estudio mediante RMN de la estructura y estabilidad de ácidos nucleicos con furanosas modificadas

    OpenAIRE

    Martín-Pintado, N.

    2013-01-01

    El objetivo general de la tesis es determinar el efecto que tienen algunas modificaciones químicas en la posición C2´ de la furanosa en la estructura y estabilidad de los ácidos nucleicos. Nos hemos centrado en modificaciones aparentemente menores, como son introducir átomos de fluor en C2´ (2´F-ANA, 2´F-RNA y dFdC*) y sus correspondientes análogos hidroxilados (ANA y RNA*), pero que tienen un notable impacto en las propiedades del oligonucleótido resultante

  16. Instrumentation in NMR/NMR imaging; Instrumentation en RMN/IRM

    Energy Technology Data Exchange (ETDEWEB)

    Favre, B.; Desgoutte, P.; Marguet, Ch. [Universite Claude Bernard, Lab. de Resonance Magnetique Nuleaire, 69 - Villeurbanne (France)

    1999-07-01

    Nuclear Magnetic Resonance (NMR) is largely used in medical imaging and in spectroscopy for the chemistry. The equipment is complex and explosive, and is not easily accessible for teaching. The didactic machine presented here allows, thanks to an extreme simplification, to approach essential notions of NMR with a cost and a space-factor reduced. It allows to visualize the phenomenon of NMR, to illustrate its main applications, and to measure main parameters concerning the magnetic field or the sample. In addition, it can be used to study signal acquisition and processing, fundamental digital and analog electronic circuits, programming... (authors)

  17. Temperature controller for NMR probes; Controlador de temperatura para sondas de RMN

    Energy Technology Data Exchange (ETDEWEB)

    Ferraz, L.F.M.; Bonagamba, T.J.; Silva, J.G. [Sao Paulo Univ., Sao Carlos, SP (Brazil). Inst. de Fisica e Quimica

    1993-12-31

    A temperature controller for NMR probes was developed. In order to control the temperature, a nitrogen gas flow was used, which may be heated by an electric resistance or cooled by passing by a transmission line submerged in liquid nitrogen. The association of liquid nitrogen cooling and electric heating enabled the sample temperature variation from -196 C to several hundred Celsius accordingly to the material of the probe. Due the dynamics of the process, a Proportional Integral and Differential (PID) controller is used. The equipment is described 3 figs.

  18. Développement de nouvelles méthodes analytiques dans l'agroalimentaire par RMN

    OpenAIRE

    Heude, Clément

    2015-01-01

    Most of the current analytical and quality control methods in the food industry are based on a targeted approach, with an upstream definition of the intended contaminants, and may fail to detect some frauds or contaminations of genuine products. It is around this issue that the Agrifood GPS (Global Protection System), of which this thesis is part of, has been initiated. This project aims at developing new holistic analytical methods (untargeted) in order to ensure the integrity of the foodstu...

  19. Caracterização estrutural de vidros fluorofosfatos utilizando metodologias de RMN

    OpenAIRE

    2014-01-01

    O presente trabalho aborda o estudo de correlações entre estrutura e propriedade de uma nova composição de vidros fluorofosfato. O trabalho compreende na síntese e caracterização de vidros fluorofosfatos com a seguinte composição: [80Ba(PO3)2 - 20Al(PO3)3]1-x[80BaF2 - 20AlF3]x(0 ≤ x ≤ 40 - mol%).Ressonância Magnética Nuclear e Espalhamento Raman são técnicas indicadas no estudo estrutural de materiais amorfos, como por exemplo, os vidros. Através dos resultados obtidos por difração de r...

  20. Estudio mediante RMN de la estructura y estabilidad de ácidos nucleicos con furanosas modificadas

    OpenAIRE

    Martín-Pintado, N.

    2013-01-01

    El objetivo general de la tesis es determinar el efecto que tienen algunas modificaciones químicas en la posición C2´ de la furanosa en la estructura y estabilidad de los ácidos nucleicos. Nos hemos centrado en modificaciones aparentemente menores, como son introducir átomos de fluor en C2´ (2´F-ANA, 2´F-RNA y dFdC*) y sus correspondientes análogos hidroxilados (ANA y RNA*), pero que tienen un notable impacto en las propiedades del oligonucleótido resultante

  1. Pressure Dependence of the Phonon Modes of Hexagonal-RMnO3

    Science.gov (United States)

    Gao, Peng; Tyson, Trevor A.; Liu, Zhenxian; Kim, Sung Baek; Cheong, Sang-Wook

    2008-03-01

    We present high pressure IR measurements of the phonon spectra of HoMnO3 and YMnO3. Measurements were conducted over the pressure range ambient to ˜20 GPa. No phase changes were observed over this broad range of hydrostatic pressures. A strong non-linear variation of frequency with pressure is observed suggesting saturation at higher pressures. A discussion of the effect of hydrostatic pressure on the ferroelectric properties of these systems will be given based on comparisons with density functional calculations.

  2. Pressure Dependence of Structure Stability of Multiferroic Hexagonal-RMnO3

    Science.gov (United States)

    Chen, Zhiqiang; Gao, Peng; Tyson, Trevor. A.; Liu, Zhenxian; Hu, Jinzhu; Zhang, Chenglin; Kim, Sung-Baek; Cheong, Sang-Wook

    2009-03-01

    We present high pressure IR and X-ray diffraction measurements of the hexagonal multiferroic systems HoMnO3, YMnO3 and LuMnO3. Measurements were conducted over the pressure range ambient to ˜20 GPa. No phase changes were observed over this broad range of hydrostatic pressures. These suggest that the hexagonal structure is stable at higher pressures. The thermal treatment is necessary to overcome the barrier (breaking and reconnection of bonds) to achieve the hexagonal to orthorhombic phase change. A discussion of the effect of hydrostatic pressure on the ferroelectric properties of these systems will be given based on comparisons with density functional calculations.

  3. NMR of amino-guanidine and derivates; RMN de aminoguanidina e derivados

    Energy Technology Data Exchange (ETDEWEB)

    Tinoco, L.W.; Figueroa Villar, Jose Daniel; Borges, M.N.; Messeder, J.C. [Instituto Militar de Engenharia (IME), Rio de Janeiro, RJ (Brazil). Secao de Quimica

    1993-12-31

    The parasitic disease known in Brazil as `Doenca de Chagas` affects millions of Brazilians and its cure is not known yet. In the search for new drugs it was discovered that bi-cationic compounds such as pentamidine compounds are active against similar diseases, however, preliminary tests for Trypanosoma cruzi (the causing agent of Doenca de Chagas) were negative. However, our preliminary studies indicate that such compounds do have active role against Trypanosoma cruzi. This work presents the preliminary NMR spectra of these compounds in order to contribute to the above mentioned issue 1 refs., figs., 5 tabs.

  4. In vivo NMR spectroscopy of the liver. Spectroscopie RMN du foie in vivo

    Energy Technology Data Exchange (ETDEWEB)

    Jehenson, P.; Cuenod, C.A.; Syrota, A. (CEA, 91 - Orsay (FR). Service Hospitalier Frederic Joliot)

    1989-01-01

    The application of in vivo MR spectroscopy to the study of the liver is currently an expanding field of research. Owing to technical difficulties, the results obtained thus far were mainly those of animal observations. Several nuclei have been considered: hydrogen, phosphorus, carbon or fluorine. This non-traumatic method allows following and quantifying the various metabolic pathways, especially during hepatic diseases. The major metabolic pathways, i.e. neoglycogenesis, glycogenolysis, Krebs' cycle, etc., are studied, as well as their alterations during diseases such as ischemia, diabetes or alcoholism. The development of this promising technique requires the cooperation of various clinical and fundamental disciplines.

  5. RMN 13C de chalcones protonées: Factorisation des interactions intramoléculaires

    Science.gov (United States)

    Membrey, François; Doucet, Jean-Pierre

    13C study of protonated para, para' disubstituted chalcones XC 6H 4CHCHC(OH) +C 6H 4Y, shows for the chemical shift of the carbenium center important deviations from a strict additivity of Substituent Induced Shifts observed in the corresponding monosubstituted ions. By collecting the experimental data into sub-populations where only one substituent (X or Y) varies—the other remaining fixed—a network of linear homogeneous correlations (δ/δ) is obtained. Their largely variable slopes indicate that the susceptibility of the carbenium site to the perturbations induced by one of the substituent groups depends on the nature of the other substituent group. The definition of 'Intrinsic Substituent Parameters' (derived from the SCS observed, in these ions, on the aromatic para positions) allows to separate the action of a substituent group on the electronic interaction mechanism and the global perturbation detected on the observation site. For a quantitative evaluation of these interactions, a Factorization Model is proposed, where deviations to additivity of the SCS are expressed as a product of the intrinsic parameters of X and Y groups. This model is successfully applied to 13C spectra of protonated chalcones and benzophenones. The parallelism between these intrinsic group effects and the SCS observed in monosubstituted benzenes points out the prime importance in these cationic systems, of π polarisation effects modulating the electron transfer toward the carbenium center within a concerted π-inductive mesomeric action.

  6. Shielding calculations using computer techniques; Calculo de blindajes mediante tecnicas de computacion

    Energy Technology Data Exchange (ETDEWEB)

    Gonzalez Portilla, M. I.; Marquez, J.

    2011-07-01

    Radiological protection aims to limit the ionizing radiation received by people and equipment, which in numerous occasions requires of protection shields. Although, for certain configurations, there are analytical formulas, to characterize these shields, the design setup may be very intensive in numerical calculations, therefore the most efficient from to design the shields is by means of computer programs to calculate dose and dose rates. In the present article we review the codes most frequently used to perform these calculations, and the techniques used by such codes. (Author) 13 refs.

  7. Demand calculations for transformer dimensioning; Calculo de demanda para dimensionamento de transformadores

    Energy Technology Data Exchange (ETDEWEB)

    Villela, Anderson Goncalves; Carvalho, Valdivino Alves de [AES Eletropaulo, SP (Brazil)

    2010-10-15

    The calculation algorithm adopted by the AES Eletropaulo, Brazil, for the dimensioning of LV transformers did not represent the real grid conditions, being necessary the development of a new method. This paper presents the new procedure, based on the application of typical load curves and the consumption of energy calculation based on the load information supplied by clients and designers. (author)

  8. Soil pro consolidation load and settlement computation; Preconsolidacion de los suelos y calculo de asentamiento

    Energy Technology Data Exchange (ETDEWEB)

    Delgado Martinez, D. E.

    2009-07-01

    It is estimated that cohesive soils are present in about in about 80% of the Cuban territory. Most of these soils are pre consolidated as a result of the country's geo-environmental conditions. That's why it is important, in the Cuban context, to determine accurately the soil pre consolidation load, correct the oedometric curve and apply these concepts to settlement computation. In this paper, a study is presented to define how to estimate the pre consolidation pressure by using several methods. A database was created. It consisted of 102 pre consolidated soils, which are typical from the central region of Cuban. These soil we analyzed by several Cuban geotechnical research centers. (Author) 12 refs.

  9. Characteristic parameters of drift chambers calculation; Calculo de los parametros caracteristicos de camaras de deriva

    Energy Technology Data Exchange (ETDEWEB)

    Duran, I.; Martinez-Laso, L.

    1989-07-01

    We present here the methods we used to analyse the characteristic parameters of drift chambers. The algorithms to calculate the electric potential in any point for any drift chamber geometry are presented. We include the description of the programs used to calculate the electric field, the drift paths, the drift velocity and the drift time. The results and the errors are discussed. (Author) 7 refs.

  10. Sugarcane exergy calculation; Calculo de la exergia de la cana de azucar

    Energy Technology Data Exchange (ETDEWEB)

    Fernandez P, Maria I.; Nebra P, Silvia A. [Universidade Estadual de Campinas, SP (Brazil). Faculdade de Engenharia Mecanica. Dept. de Energia]. E-mails: mariai@fem.unicamp.br.; sanebra@fem.unicamp.br; Martinez R, Arnaldo [Universidade de Oriente, Santiago de Cuba (Cuba). Facultad de Ingenieria Mecanica. Centro de Estudios de Refrigeracion Luis Fernando Brossard Perez]. E-mail: arnaldo@fim.ceefe.uo.edu.cu

    2000-07-01

    This paper presents a sugarcane exergy calculation, carried out considering the material as constituted by dry fiber and juice, being the last one that includes all the sucrose and water present in sugarcane. The variation intervals of sugarcane chemical composition and consequently the chemical composition of fibre and juice were obtained from a bibliography research. the finals results show that, the fibre exergy, as was considered totally dry and without sucrose, is a function of it chemical composition only. The quotient between the exergy and low calorific value has a middle value of 1,14 and the middle value of it exergy was 2329 kJ/kg of cane. Based on the environmental reference proposed by Szargut for the sugarcane juice exergy determination, it was obtained that the mixture component of the juice exergy has no piratical influence in the total exergy juice value, being the value of the reactive exergy component the determining of a middle value of sugarcane juice exergy of 2814,25 kJ/kg of juice and 2380Kj/Kg of cane. The sugarcane exergy value obtained for 8-18% of fiber, 75-82% of water and 14.5-22% of sucrose was 4709Kj/kg of cane. (author)

  11. Subcritical calculation of the nuclear material warehouse;Calculo de subcriticidad del almacen del material nuclear

    Energy Technology Data Exchange (ETDEWEB)

    Garcia M, T.; Mazon R, R., E-mail: teodoro.garcia@inin.gob.m [ININ, Carretera Mexico-Toluca s/n, 52750 Ocoyoacac, Estado de Mexico (Mexico)

    2009-07-01

    In this work the subcritical calculation of the nuclear material warehouse of the Reactor TRIGA Mark III labyrinth in the Mexico Nuclear Center is presented. During the adaptation of the nuclear warehouse (vault I), the fuel was temporarily changed to the warehouse (vault II) and it was also carried out the subcritical calculation for this temporary arrangement. The code used for the calculation of the effective multiplication factor, it was the Monte Carlo N-Particle Extended code known as MCNPX, developed by the National Laboratory of Los Alamos, for the particles transport. (Author)

  12. Calculation of reactivity without Lagrange interpolation; Calculo de la reactividad sin interpolacion de Lagrange

    Energy Technology Data Exchange (ETDEWEB)

    Suescun D, D.; Figueroa J, J. H. [Pontificia Universidad Javeriana Cali, Departamento de Ciencias Naturales y Matematicas, Calle 18 No. 118-250, Cali, Valle del Cauca (Colombia); Rodriguez R, K. C.; Villada P, J. P., E-mail: dsuescun@javerianacali.edu.co [Universidad del Valle, Departamento de Fisica, Calle 13 No. 100-00, Cali, Valle del Cauca (Colombia)

    2015-09-15

    A new method to solve numerically the inverse equation of punctual kinetics without using Lagrange interpolating polynomial is formulated; this method uses a polynomial approximation with N points based on a process of recurrence for simulating different forms of nuclear power. The results show a reliable accuracy. Furthermore, the method proposed here is suitable for real-time measurements of reactivity, with step sizes of calculations greater that Δt = 0.3 s; due to its precision can be used to implement a digital meter of reactivity in real time. (Author)

  13. La Vision que tienen del Calculo los Diplomados en Empresariales: Un Test Final

    Directory of Open Access Journals (Sweden)

    Seijas Macías, J. Antonio

    2008-01-01

    Full Text Available Como docentes de Matemáticas Aplicadas a la Economía y Empresa somos conscientes de las a veces difíciles relaciones entre ambas disciplinas. ¿En qué sentido se diluyen las matemáticas en la economía? ¿Qué queda de ellas en los alumnos de empresa al acabar la carrera? ¿El lenguaje matemático sigue teniendo significado para ellos? Este trabajo pretende responder a estas preguntas tomando como referencia un test pasado a los alumnos del último año de la diplomatura de Ciencias Empresariales de la Universidad de A Coruña.

  14. Shield calculations, optimization vs. paradigm; Calculos de blindajes, optimizacion vs. paradigma

    Energy Technology Data Exchange (ETDEWEB)

    Cornejo D, N.; Hernandez S, A.; Martinez G, A. [Centro de Proteccion e Higiene de las Radiaciones, Calle 20 No. 4113 e/41 y 47 Playa C.P. 11300 LaHabana (Cuba)]. e-mail: nestor@cphr.edu.cu

    2006-07-01

    Many shieldings have been designed under the criteria of 'Maximum dose rates of project'. It has created the paradigm of those 'low dose rates', for the one which not few specialists would consider unacceptable levels of dose rate superior to the units of {mu}Sv.h{sup -1}, independently of the exposure times. At the present time numerous shieldings are being designed considering dose restrictions in real times of exposure. After these new shieldings, the dose rates could be notably superior to those after traditional shieldings, without it implies inadequate designs or constructive errors. In the work significant differences in levels of dose rates and thickness of shieldings estimated by both methods for some typical facilities. It was concluded that the use of real times of exposure is more adequate for the optimization of the Radiological Protection, although this method demands bigger care in its application. (Author)

  15. Equations for calculating pressure loss; Ecuaciones para el calculo de perdida de carga

    Energy Technology Data Exchange (ETDEWEB)

    Cifre Vicens, B. [Hospital Son dureta, Plama de Mallorca, (Spain)

    1995-12-31

    Friction`s factor calculation is necessary for the determination of pressure loss, generally relied on the Colebrook equation which, since it is implicit, is difficult to apply using computers. A thorough review of the literature published since 1939 on the most commonly used equations is provided, establishing the validity range and relative error according to each author. The Churchill equation is recommended for use with computers as it allows calculations to be made in laminar and eddying flow areas. (Author) 17 refs.

  16. O ambiente e a modelagem matematica no ensino do calculo numerico

    OpenAIRE

    Nilson Sergio Peres Stahl

    2003-01-01

    Resumo: Este trabalho de pesquisa trata da utilização da Modelagem Matemática Aplicada a fenômenos Ambientais como meio de transformação de atitudes docentes e discentes no processo aprendizagem/ensino da disciplina de Cálculo Numérico. A pesquisa se desenvolveu numa instituição privada em que os alunos do quarto ano do curso de licenciatura em Matemática, em 1999, participaram como atores do processo. Foram aplicados 7 projetos enfocando o meio...

  17. Modelizando el calculo de varias variablEEES en el aula

    OpenAIRE

    Aragón Ángel, María Ángeles; Cubarsí Morera, Rafael

    2011-01-01

    La implantaci on de la modelizaci on matem atica en el ambito del Espacio Europeo de Educaci on Superior (EEES) necesita de una revisi on y adaptaci on de los contenidos y estrategias para abordar las asignaturas, en particular, aquellas m as te oricas y abstractas, para fomentar su car acter interdisciplinario. Se presenta una nueva propuesta metodol ogica para la asignatura de An alisis Vectorial (c alculo multivariable) ofertada durante los ultimos a~nos por l'Escola T ecn...

  18. Methodology for the calculation of load limits; Metodologia para o calculo de limites de carregamento

    Energy Technology Data Exchange (ETDEWEB)

    Ramos, Dorel Soares [Companhia Energetica de Sao Paulo, SP (Brazil); Bezerra, Luis Roberto [FURNAS Centrias Eletricas S.A., Rio de Janeiro, RJ (Brazil); Gesualdi Junior, Luis Carlos [Light Servicos de Eletricidade SA, Rio de Janeiro, RJ (Brazil); Portela, Carlos Medeiros

    1987-10-01

    The maximization of the usage of the equipment and therefore, the reduction in the investments in the expansion of electric power transmission systems has been a great worry to the Brazilian electric power system. This work describes a digital simmulation methodology to the evaluation of load limits in transformers 16 refs.

  19. Validation in life for dosimetric calculations in PET; Validacion de vida para calculos dosimetricos en PET

    Energy Technology Data Exchange (ETDEWEB)

    Ocampo ramos, J. C.; Petoussi-Henss, N.; Zankl, M.

    2015-07-01

    The LIFE program (VOXEL-PHANTOM-BASED SOFTWARE FOR INTERNAL DOSE ASSESSMENT) is developing new software for dose assessment in patients undergoing nuclear medicine examinations. This paper shows some of the validation and comparison tests that have been carried out for the case of the F-18 FDG. Unlike current programs (eg. OLINDA) using phantoms stylized size reference, the new developed software uses the pre calculated library Specific Absorption Fractions (SAF) of photons and electrons based on different anthropomorphic phantoms voxelized and the SAF new computational phantoms of the ICRP for photons, electrons, neutrons and alphas. In addition, the software uses the latest information from nuclear decay of the ICRP 107 (2008). The software is being widely put on trial and comparison with other methods of calculation available. (Author)

  20. Computational program to neutron flux calculation; Programa computacional para calculo de fluxo de neutrons

    Energy Technology Data Exchange (ETDEWEB)

    Souza, Maria Ines Silvani; Furieri, Rosanne Cefaly de Aranda Amado [Instituto de Engenharia Nuclear (IEN), Rio de Janeiro, RJ (Brazil)

    2000-07-01

    The absolute value of the neutron flux is of paramount importance in reactor physics and other application on the nuclear field. Due to several corrections which should be done, such as radioactive decay of the produced nuclides, normalization factors between different irradiations, neutron spectrum perturbation, cross section behaviour and growing of the reactor power, among other factors, make the calculation of the neutron flux very cumbersome. the software FLUXO was developed to overcome these inconveniences. It is programmed in FORTRAN language, and was written to calculate the absolute flux of thermal, epithermal and fast neutrons, through the foil activation technique. The magnitude of this activation can be measured by a 4{pi} {beta}-{gamma} coincidence measurement or by gamma spectroscopy alone. The software calculates as well, the absolute activity of radioactive sources, and reactor-irradiated samples. (author)

  1. Modelizando el calculo de varias variablEEES en el aula

    OpenAIRE

    Aragón Ángel, María Ángeles; Cubarsí Morera, Rafael

    2011-01-01

    La implantaci on de la modelizaci on matem atica en el ambito del Espacio Europeo de Educaci on Superior (EEES) necesita de una revisi on y adaptaci on de los contenidos y estrategias para abordar las asignaturas, en particular, aquellas m as te oricas y abstractas, para fomentar su car acter interdisciplinario. Se presenta una nueva propuesta metodol ogica para la asignatura de An alisis Vectorial (c alculo multivariable) ofertada durante los ultimos a~nos por l'Escola T ecn...

  2. Un error en los calculos matematicos destroza el acelerador de particulas del CERN

    CERN Multimedia

    Cernuda, Olalla

    2007-01-01

    The most famous particle accelerator in the world, who is at CERN, has suffered a catastrophic damage after a great explosion took place in its depths. This explosion has an absolutely scientific explanation: a mathematical mistake in the design of the anchorages of great magnets. (1 page)

  3. BASIC Program for the calculation of radioactive activities; Programa BASIC para el calculo de actividades radiactivas

    Energy Technology Data Exchange (ETDEWEB)

    Cortes P, A.; Tejera R, A.; Becerril V, A

    1990-04-15

    When one makes a measure of radioactive activity with a detection system that operates with a gamma radiation detector (Ge or of NaI (Tl) detector), it is necessary to take in account parameters and correction factors that making sufficiently difficult and tedious those calculations to using a considerable time by part of the person that carries out these measures. Also, this frequently, can to take to erroneous results. In this work a computer program in BASIC language that solves this problem is presented. (Author)

  4. Calculo de volúmenes en modelos remallados de elementos finitos

    Directory of Open Access Journals (Sweden)

    Andrés Lapuebla-Ferri

    2011-06-01

    Full Text Available El Método de los Elementos Finitos asistido por ordenador es una herramienta muy extendida en ingeniería. En ciertas aplicaciones, se precisa modificar la malla del modelo a lo largo del proceso de simulación, lo que se conoce como remallado. En estos casos, además, suele ser necesario realizar mediciones en el modelo de elementos finitos, como por ejemplo calcular el volumen de ciertas regiones del mismo. Los paquetes comerciales disponibles en la actualidad permiten satisfacer algunas de estas necesidades, aunque adolecen de ciertas limitaciones. En este trabajo se presenta una aplicación desarrollada en el código propio de MatlabQc, que permite el cálculo aproximado del volumen de una región del espacio comprendida entre una malla de elementos finitos cuadriláteros lineales y otra malla topológicamente equivalente a la anterior, esta última obtenida a través de un proceso de remallado.

  5. ESTUDIO TEÓRICO DE LA MOLÉCULA DE HIDROGENO CALCULO AB-INITIO

    Directory of Open Access Journals (Sweden)

    N. Quitián

    2010-09-01

    Full Text Available Utilizando la técnica LCGO-SCF-MO (Combinación Lineal de los Orbitales Moleculares en Orbitales Gausianos, en el método del Campo Auto-Coherente, se determinaron las energías de orbital, la energía electrónica total, la energía de repulsión nuclear y la energía de Hartree-Fock de la molécula de hidrógeno en su estado fundamental, mediante un cálculo ab initio y utilizando una base de funciones gausianas. Los orbitales moleculares fueron desarrollados en términos de una función Is contraída por átomo de hidrógeno, obtenida por la minimización de los coeficientes y de los exponentes de los orbitales gausianos para el átomo aislado. Los resultados obtenidos nos permiten afirmar que la base molecular mejora sensiblemente los resultados, acercándose más al límite de Hartree-Fock.

  6. Calculo de Parámetros Electrónicos Para el Grafito Bernal

    Directory of Open Access Journals (Sweden)

    Claudia Villaquirán

    2002-06-01

    Full Text Available Using ab-initio calculation, we have computed different electronic parameters associated with the transport coefficients of graphite Bernal. Software CRYSTAL¹ was used with a Pople standard STO- 21G* basis set. Different hamiltonians were tested, choosing a restricted Hartree-Fock one, because it generated the best qualitative results. All graphites studied present a valence bandwidth near 0.60 a.u., in agreement with the literature. In hexagonal Bernal graphite the splitting of the valence P band was accentuated, and E F = -0.00140 a.u. The surface Fermi is located around the HKH edge of the first Brillouin zone. In general such surfaces present a central electron orbit of maximal size in the plane, which diminish in size when the z component of the vector moves in KH direction. Integrating on the surface Fermi calculates the time relaxation parallel and the time relaxation perpendicular and finally we evaluate the parallel and perpendicular resistivity.

  7. Propriedad intelectual en el marco del acuerdo Mercosur – Union Europea de 1995: apuntes teoricos para las negociaciones intercontinentales (1999-2002

    Directory of Open Access Journals (Sweden)

    Astrid Uzcátegui

    2002-09-01

    Full Text Available El presente artículo buscapresentar consideraciones científicas sobrela propiedad intelectual que pueden ser utilizadaspor los negociadores intercontinentalesdel Mercado Común del Sur convistas a alcanzar mejores resultados en elcomplejo proceso de negociación con laUnión Europea que resultará en la primeraZona de Libre Comercio entre dos unionesaduaneras a escala intercontinental. En estesentido, la superación de las eventualestrabas por los dos bloques regionales daráal mundo una verdadera prueba de lavalidez de un regionalismo abierto.Abstract: The present article presentsscientific considerations on intellectualproperty which may be used by intercontinentalnegotiators of the Mercosur, with theaim of accomplishing better results in thecomplex negotiation process whose resultwill be the first Free Trade Zone betweentwo customs unions in an intercontinentalscale. In this sense, overcoming eventualobstacles between these two regional blockswill offer the world a true evidence of thevalidity of an open regionalism.

  8. Theoretical study on air flow in a solar chimney with real insulation conditions; Estudo teorico do escoamento de ar em uma chamine solar com condicoes reais de insolacao

    Energy Technology Data Exchange (ETDEWEB)

    Ferreira, Andre Guimaraes; Cortez, Marcio Fonte-Boa; Molina Valle, Ramon; Brasil, Cristiana Santiago [Minas Gerais Univ., Belo Horizonte, MG, (Brazil). Dept. de Engenharia Mecanica]. E-mail: ferreira@demec.ufmg.br

    2000-07-01

    This paper presents a theoretical analysis of the turbulent air flow with real conditions of insulation inside a solar chimney. The flow is described by the mass, momentum and energy conservation equations, besides the transport equations of the quantities in the turbulence model (k and epsilon). Dimensionless parameters are presented at way out the device, as function of time and the insulation conditions, represented by the soil and the roof heating.

  9. Development of a monoenergetic neutron beam (Theoretical aspects, experimental developments and applications); Desarrollo de un haz de neutrones monoenergeticos (Aspectos teoricos, desarrollos experimentales y aplicaciones)

    Energy Technology Data Exchange (ETDEWEB)

    Varela G, A

    2003-07-01

    By the use of a neutron time of flight system at the Tandem Accelerator of the National Nuclear Research Institute; with neutrons provided by means of the {sup 2} H(d, n) {sup 3} He we intend to use the associated particle technique in order to have monoenergetic neutrons. This neutron beam will be used both in basic and applied research. (Author)

  10. {sup 137}Cs applicability to soil erosion assessment: theoretical and empirical model; Aplicabilidade do {sup 137}Cs para medir erosao do solo: modelos teoricos e empiricos

    Energy Technology Data Exchange (ETDEWEB)

    Andrello, Avacir Casanova

    2004-02-15

    The soil erosion processes acceleration and the increase of soil erosion rates due to anthropogenic perturbation in soil-weather-vegetation equilibrium has influenced in the soil quality and environment. So, the possibility to assess the amplitude and severity of soil erosion impact on the productivity and quality of soil is important so local scale as regional and global scale. Several models have been developed to assess the soil erosion so qualitative as quantitatively. {sup 137}Cs, an anthropogenic radionuclide, have been very used to assess the superficial soil erosion process Empirical and theoretical models were developed on the basis of {sup 137} Cs redistribution as indicative of soil movement by erosive process These models incorporate many parameters that can influence in the soil erosion rates quantification by {sup 137} Cs redistribution. Statistical analysis was realized on the models recommended by IAEA to determinate the influence that each parameter generates in results of the soil redistribution. It was verified that the most important parameter is the {sup 137} Cs redistribution, indicating the necessity of a good determination in the {sup 137} Cs inventory values with a minimum deviation associated with these values. After this, it was associated a 10% deviation in the reference value of {sup 137} Cs inventory and the 5% in the {sup 137} Cs inventory of the sample and was determinate the deviation in results of the soil redistribution calculated by models. The results of soil redistribution was compared to verify if there was difference between the models, but there was not difference in the results determinate by models, unless above 70% of {sup 137} Cs loss. Analyzing three native forests and an area of the undisturbed pasture in the Londrina region, can be verified that the {sup 137} Cs spatial variability in local scale was 15%. Comparing the {sup 137} Cs inventory values determinate in the three native forest with the {sup 137} Cs inventory value determinate in the area of undisturbed pasture in the Londrina region, was verified that there was not difference in the values, so that the {sup 137} Cs inventory determinate in area of native forest can be used to represent the reference value of {sup 137} Cs inventory. Comparing the {sup 137}Cs inventory values determinate to Londrina region with the {sup 137} Cs inventory value determinate in an area of the native pasture in the Porto Alegre region, the {sup 137} Cs spatial variability in the regional scale was 15%, but when was compared with the {sup 137} Cs inventory determinate in the Piracicaba region, the {sup 137} Cs spatial variability was 37%. Utilizing soil erosion plots in the experimental area of the IAPAR (Londrina), can be verified that the proportional model is a good approximation to determine the soil redistribution, but when were utilized soil erosion plots in the experimental area of the UFRGS, it was not so evident. Although there was influence of the parameters incorporated in the models on the results, due to 137 Cs spatial variability that gives deviation in the results of models, there was not difference between the results of models. So, it is convenient to utilize the proportional model, the most simple and easy to use, to assess the soil redistribution, which gives similar results to the most sophisticated models when the deviation is taking to account. (author)

  11. La Contribución de Louk Hulsman a un Modelo Crítico de la Justicia Restaurativa: Breves Apuntamentos Teoricos

    Directory of Open Access Journals (Sweden)

    Daniel Silva Achutti

    2016-06-01

    Full Text Available Se pretende en este trabajo abordar las principales críticas de Louk Hulsman al sistema penal, para después comprobar si pueden ser considerados importantes también para la creación de un modelo crítico de la justicia restaurativa. El objetivo es apuntar así a la importancia estratégica del pensamiento y la obra de Hulsman para la estructuración de la justicia restaurativa desde una perspectiva crítica, consciente de los conocidos problemas del sistema penal

  12. Exhaustion of the Brazilian electric sector regulatory model: theoretical versus practical aspects; Esgotamento do modelo regulatorio do setor eletrico brasileiro: aspectos teoricos versus aspectos praticos

    Energy Technology Data Exchange (ETDEWEB)

    Pereira, Marcio Giannini; Carpio, Lucio Guido Tapia [Universidade Federal, Rio de Janeiro, RJ (Brazil). Coordenacao dos Programas de Pos-graduacao de Engenharia. Programa de Planejamento Energetico]. E-mails: marciogiannini@hotmail.com; guido@ppe.ufrj.br

    2002-07-01

    The recent Brazilian regulatory experience demonstrates that it is no easy the changing for a new performance and behaviour model in the electric sector, mainly when it is observed the distance among initial objectives of the reform and the obtained results. The reforms introduction in the sector, which in ultimate analysis aimed the efficiency increasing in the sector, supported by a fragile institutional structure and regulatory collapse, obtained as unfolding the crisis of the electric power in 2001. (author)

  13. Biomass gasification in fixed bed type down draft: theoretical and experimental aspects; Gasificacao de biomassa em leito fixo tipo concorrente: aspectos teoricos e experimentais

    Energy Technology Data Exchange (ETDEWEB)

    Martinez, Juan Daniel; Andrade, Rubenildo Vieira; Lora, Electo Eduardo Silva [Universidade Federal de Itajuba (UNIFEI), MG (Brazil). Inst. de Engenharia Mecanica. Nucleo de Excelencia em Geracao Termeletrica e Distribuida

    2008-07-01

    Actually are recognizing the advantages of biomass in reducing dependence on fossil fuels and significant reduction in emissions of greenhouse effect gases such as Co2. Also are known the different conversion of biomass routes for their use or exploitation, such as thermochemical process (gasification, pyrolysis and combustion), the biological process (fermentation and transesterification) and the physical process (densification, reducing grain and mechanical pressing). In this sense, the gasification is regarded as the most promising mechanism to obtain a homogeneous gaseous fuel with sufficient quality in the small scale distributed generation. This work presents some aspects of biomass gasification in fixed bed, as well as some preliminary results in the evaluation and operation of fixed bed down draft gasifier with double stage air supply of the NEST, identifying the adequate air supply quantity (equivalence ratio in the range of 0,35 to 0,45) for obtaining a fuel gas with lower heating value around 4 MJ/N m3. (author)

  14. Theoretical aspects of the Semkow fractal model in the radon emanation in solids; Aspectos teoricos del modelo fractal de Semkow en la emanacion de radon en solidos

    Energy Technology Data Exchange (ETDEWEB)

    Cruz G, H.S. [Instituto Nacional de Investigaciones Nucleares, A.P. 18-1027, 11801 Mexico D.F. (Mexico)

    1997-07-01

    The basic elements of the Fractals theory are developed. The physical basis of radon emission in solids are described briefly. It is obtained that the emanation power E{sub R} of mineral grains is scaled as r{sub 0} {sup D-3} (r{sub 0} : grain radius). From a logarithmic graph E{sub R} versus grain size is deduced the fractal dimension of the emanation surface. The experimental data of different materials give an interval in the fractal dimension D between 2.1 and 2.8 (Author)

  15. Proceedings of the 7. Brazilian meeting on magnetic resonance. Workshop 'RMN Applications'. Abstracts; Anais da 7. Jornada brasileira de ressonancia magnetica. Workshop 'Aplicacoes da RMN'. Resumos

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2002-07-01

    These proceedings contains the abstracts of the papers presented during the 7. Brazilian meeting on Magnetic Resonance. The main objective of this event was the dissemination of the scientific research and exchange of ideas in the different fields of the Magnetic Resonance: Electron Spin Resonance, Nuclear Quadrupole Resonance, Electron Double Resonance, Moessbauer Effect and Nuclear Magnetic Resonance (NMR), including all theoretical and experimental aspects of theses techniques, as well as their applications in the study of natural products, radiopharmaceuticals, biomolecules, polymers and catalyzers and inquiries in the areas of petrochemical, material sciences, organic and inorganic chemistry, biochemistry, physics, physiology, geology and medicine.

  16. The Norm NOM-008-ENER-2001 offers an important saving option; La Norma NOM-008-ENER-2001 ofrece una importante opcion de ahorro

    Energy Technology Data Exchange (ETDEWEB)

    Lalana, Emiliano Ramiro [Fideicomiso para el Ahorro de la Energia Electrica (Mexico)

    2006-01-15

    The Norm NOM-008-ENER-2001 no longer commands the efficient handling of energy from functional equipment or apparatuses but from a well planned architectural design that allows diminishing the energy use for cooling purposes, consequently this Norm refers to the conduction and radiation principles regulating the heat gain through the cover portions of a building. The Norm defines a reference theoretical building that will dictate the propitious heat gain for the projected buildings. Here the functioning logic of the Norm in respect to both principles is mathematically explained as well as an application example is developed considering the calculations made for the Norm's reference building and for the projected one, the final revision of the fulfillment of the norm, proposals of solutions and the conclusions. [Spanish] La Norma NOM-008-ENER-2001 comanda el manejo eficiente de energia electrica ya no a partir de equipos o aparatos funcionales sino a partir de un bien planeado diseno arquitectonico que permita disminuir el uso de energia para fines de enfriamiento. Por ende, esta norma se refiere a los principios de conduccion y radiacion regulando la ganancia de calor a traves de la envolvente y porciones de un edificio. La Norma define un edificio teorico de referencia que dictara la ganancia de calor propicia para los edificios proyectados. Aqui se explica matematicamente la logica de funcionamiento de la Norma respecto a ambos principios asi como se desarrolla un ejemplo de aplicacion que considera los calculos realizados para el edificio de referencia de la Norma y para el proyectado, la revision final del cumplimiento de la Norma, propuestas de solucion y conclusiones.

  17. Implementing a system of structured clinical supervision with a group of DipHE(nursing) RMN students.

    Science.gov (United States)

    Markham, V; Turner, P

    1998-01-01

    Clinical supervision is to become an integral part of mental health nursing, and the United Kingdom Central Council for Nursing, Midwifery & Health Visiting has recommended that it be incorporated in pre-registration education. This paper describes teachers' experiences of delivering a programme of clinical supervision education within the mental health branch of a diploma in nursing course. It outlines the implementation and evaluation of the programme, including discussion of the process and difficulties encountered. The programme appears to have provided a positive first experience for the students and to have given them the enthusiasm to adopt clinical supervision as part of their future roles as qualified practitioners.

  18. Simulação de sinais de RMN através das equações de Bloch

    Directory of Open Access Journals (Sweden)

    Tiago Bueno Moraes

    2014-01-01

    Full Text Available The aim of this paper was to present a simple and fast way of simulating Nuclear Magnetic Resonance signals using the Bloch equations. These phenomenological equations describe the classical behavior of macroscopic magnetization and are easily simulated using rotation matrices. Many NMR pulse sequences can be simulated with this formalism, allowing a quantitative description of the influence of many experimental parameters. Finally, the paper presents simulations of conventional sequences such as Single Pulse, Inversion Recovery, Spin Echo and CPMG.

  19. Effect of inversion symmetry on the incommensurate order in multiferroic RMn2O5 ( R=rare earth)

    Science.gov (United States)

    Harris, A. B.; Kenzelmann, M.; Aharony, Amnon; Entin-Wohlman, O.

    2008-07-01

    Starting from the irreducible representations of the group of the wave vector, we construct the spin-wave functions consistent with inversion symmetry, neglected in the usual representation analysis. We obtain the relation between the basis functions of different members of the star of the wave vector. We introduce order parameters and determine their transformation properties under the operations of the space group of the paramagnetic crystal. The results are applied to construct terms in the magnetoelectric interaction, which are quadratic and quartic in the magnetic order parameters. The higher-order magnetoelectric interactions can in principle induce components of the spontaneous polarization, which are not allowed by the lowest-order magnetoelectric interaction. We also obtain the relation between the spin-wave functions of the incommensurate phase and those of the commensurate phase, which lead to analogous relations between the order parameters of these two phases.

  20. [mu]SR magnetic response in frustrated antiferromagnets of type RMn[sub 2] (R = rare earth)

    Energy Technology Data Exchange (ETDEWEB)

    Weber, M. (Physics Dept., TU Munich, Garching (Germany)); Asch, L. (Physics Dept., TU Munich, Garching (Germany)); Kratzer, A. (Physics Dept., TU Munich, Garching (Germany)); Kalvius, G.M. (Physics Dept., TU Munich, Garching (Germany)); Muench, K.H. (Physics Dept., TU Munich, Garching (Germany)); Ballou, R. (Lab. Louis Neel, CNRS, 38 Grenoble (France)); Deportes, J. (Lab. Louis Neel, CNRS, 38 Grenoble (France)); Waeppling, R. (Dept. of Physics, Univ. of Uppsala (Sweden)); Litterst, F.J. (Inst. for Metal Physics, TU Braunschweig (Germany)); Klauss, H.H. (Inst. for Metal Physics, TU Braunschweig (Germany)); Niedermayer, C. (Faculty for Physics, Univ. Konstanz (Germany)); Chappert, J. (CEA/DRFMC, CEN Grenoble, 38 (France))

    1994-07-01

    Zero, longitudinal and transverse field [mu]SR was carried out in the antiferromagnets YMn[sub 2], Y[sub 0.95] Tb[sub 0.15] Mn[sub 2], Y[sub 0.9]Tb[sub 0.1]Mn[sub 2], Y[sub 0.99] Sc[sub 0.01] Mn[sub 2], Y[sub 0.98]Sc[sub 0.02]Mn[sub 2] and TbMn[sub 2]. The dynamics of Mn magnetic moments above T[sub N] is typical for an itinerant antiferromagnet. Within a certain temperature range above T[sub N] part of the material enters a randomly ordered (spin glass like) magnetic state as an out-come of frustration. At temperatures above [approx] 150 K the muon spin relaxation rate indicates that the muon has become mobile. (orig.)

  1. NMR studies of chalcones isolated from Neoraputia magnifica; Estudos por RMN de chalconas isoladas de Neoraputia magnifica

    Energy Technology Data Exchange (ETDEWEB)

    Tomazela, Daniela M.; Rodrigues Filho, Edson; Silva, M. Fatima das G. F. da; Fernandes, Joao B.; Vieira, Paulo C. [Sao Carlos Univ., SP (Brazil). Dept. de Quimica

    1997-12-31

    From Neoraputia magnifica (Rutaceae) we isolated two chalcones belonging to the 1,3-diarylprop-2-en-1-one group. The two chalcones presented two or three methoxyl groups at ring B; a dimethychromene between C-5`and O-6`and also an additional methoxyl at ring A. It has been noted that H-{beta} and C-{beta} of a chalcone are more deshielded than H-{alpha}. However, HMOC and HMBC experiments of the chalcones described here showed the opposite situation where H-{alpha} is more deshielded than H-{beta}. (author) 5 refs., 4 figs., 7 tabs.

  2. Evaluation of PHB nanocomposite by low field NMR;Avaliacao de nanocompositos de PHB por RMN de baixo campo

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Mariana Bruno Rocha e; Tavares, Maria Ines Bruno, E-mail: mibt@ima.ufrj.b [Universidade Federal do Rio de Janeiro (IMA/UFRJ), RJ (Brazil). Inst. de Macromoleculas Eloisa Mano

    2009-07-01

    Poly(3-hydroxybutyrate) (PHB) based on nanocomposites containing different amounts of a commercial organically modified clay (viscogel B8) were prepared employing solution intercalation method. The relationship among the processing conditions; molecular structure and intermolecular interaction, between both nanocomposite components, were investigated using a nuclear magnetic resonance (NMR), as a part of characterization methodology, which has been used by Tavares et al. It involves the proton spin-lattice relaxation time, T1 H, by solid state nuclear magnetic resonance, employing low field NMR. X-ray diffraction was also employed because it is a conventional technique, generally used to obtain the first information on nanocomposite formation. Changes in PHB crystallinity were observed after the organophilic nanoclay had been incorporated in the polymer matrix. These changes, in the microstructure, were detected by the variation of proton nuclear relaxation time values and by X-ray, which showed an increase in the clay interlamellar space due to the intercalation of the polymer in the clay between lamellae. (author)

  3. Estudio cinético de la interconversión de Astilbina mediante espectroscopia de 1H-rmn

    Directory of Open Access Journals (Sweden)

    Omar Estrada

    2012-12-01

    Full Text Available The interconversion kinetics of astilbin to a mixture of their respective diasteroisomers was studied by nuclear magnetic resonance spectroscopy using selective irradiation experiments (TOCSY in dimethylsulfoxide. It is proposed a model which allowed establishing a trend to equilibrium for H-3 (astilbin interconversion to neoisoastilbin

  4. Evidencias de hidrógenos metilénicos gemínales no equivalentes en RMN

    OpenAIRE

    2009-01-01

    Se estudian los espectros de RMP para compuestos del tipo PcSi [OCH(CH2Y2)]2 en donde Y = NME2, QEt, NH2 y SH. En cuatro de estas ftalocianinas los protrones metilénicos no son equivalentes. Se demuestra que la agrupación YCH2 CH en los primeros dos derivados constituyen nítidamente un sistema de acoplamiento de espines AMX.

  5. NMR study of hydrated calcium silicates; Etude par RMN de la structure des silicates de calcium hydrates

    Energy Technology Data Exchange (ETDEWEB)

    Klur, I

    1996-02-26

    Radioactive wastes storage methods are developed by the CEA. As cements are important materials as well for hours living radioisotopes than for years living radioisotopes, a better knowledge of this material will allow to anticipate its behaviour and to obtain safer storage methods. The structure of calcium silicates (C-S-H) (main constituent of cements) have then been determined in this thesis by nuclear magnetic resonance. This method has allow to explain in structural terms, the different calcium rates that can be measured in the C-S-H too. (O.M.) 101 refs.

  6. DADOS ESPECTROSCÓPICOS DE DITERPENOS LABDÂNICOS: UMA ANÁLISE TEÓRICA VIA RMN E DFT

    Directory of Open Access Journals (Sweden)

    Fabrine S. de Souza

    2015-05-01

    Full Text Available Labdane diterpenes exhibit important bioactivities such as cardiovascular effects in rats as well as effects in the treatment of autoimmune diseases and Alzheimer syndrome. Recently, the labdane diterpenes ent-13-epi-manoil oxide, ribenone and ribenol were isolated from Croton palanostigma. The computational method DFT/B3LYP/cc-pVDZ was used to optimize the structures of these diterpenes and to calculate infrared data. Chemical shifts (δH and δC of the minimum energy structures (local minimum were calculated and compared with the experimental data. Comparison of the NMR data by simple linear regression (SLR showed satisfactory statistical results with a correlation coefficient (R2 and predictive ability (Q2 of over 98%. The predicted NMR data were used to confirm the δH values that have not been published.

  7. Evidencias de hidrógenos metilénicos gemínales no equivalentes en RMN

    Directory of Open Access Journals (Sweden)

    Jaime Bernal Castillo

    2009-07-01

    Full Text Available Se estudian los espectros de RMP para compuestos del tipo PcSi [OCH(CH2Y2]2 en donde Y = NME2, QEt, NH2 y SH. En cuatro de estas ftalocianinas los protrones metilénicos no son equivalentes. Se demuestra que la agrupación YCH2 CH en los primeros dos derivados constituyen nítidamente un sistema de acoplamiento de espines AMX.

  8. Spin fluctuations and structural modifications in frustrated multiferroics RMnO3 (R=Y, Lu) at high pressure

    Science.gov (United States)

    Kozlenko, D. P.; Kichanov, S. E.; Lukin, E. V.; Lee, S.; Park, J.-G.; Savenko, B. N.

    2010-06-01

    The crystal and magnetic structures of hexagonal manganites YMnO3 and LuMnO3 have been studied by powder neutron diffraction up to 6 GPa in the temperature range of 10-300 K. At ambient pressure, a triangular antiferromagnetic (AFM) state of a Γ1 irreducible representation is stable below T N=70 K in YMnO3. Upon application of high pressure, a spin-reorientation was observed and the triangular AFM structure evolves from Γ1 to Γ1+Γ2 representation symmetry. In LuMnO3, the triangular AFM state of a Γ2 symmetry with T N ≈ 95 K remains stable in the investigated pressure range. The ordered Mn magnetic moment is suppressed at high pressure and low temperature, with much more pronounced effects for YMnO3, indicating enhanced spin fluctuations due to stronger magnetic frustration of the triangular lattice under higher pressure. The relationship between the evolution of spin fluctuations and in-plane Mn-O bonds under pressure is analyzed.

  9. X-ray resonant magnetic scattering investigations of hexagonal multiferroics RMnO3 (R = Dy, Ho, Er)

    Energy Technology Data Exchange (ETDEWEB)

    Nandi, Shibabrata [Iowa State Univ., Ames, IA (United States)

    2009-01-01

    Electricity and magnetism were unified into a common subject by James Clerk Maxwell in the nineteenth century yielding the electromagnetic theory. Four equations govern the dynamics of electric charges and magnetic fields, commonly known as Maxwell's equations. Maxwell's equations demonstrate that an accelerated charged particle can produce magnetic fields and a time varying magnetic field can induce a voltage - thereby linking the two phenomena. However, in solids, electric and magnetic ordering are most often considered separately and usually with good reason: the electric charges of electrons and ions are responsible for the charge effects, whereas the electron spin governs magnetic properties.

  10. Use of NMR as an online sensor in industrial processes; Uso da RMN como um sensor online em processos industriais

    Energy Technology Data Exchange (ETDEWEB)

    Andrade, Fabiana Diuk de [Universidade de Sao Paulo (IQSC/USP), Sao Carlos, SP (Brazil). Inst. de Quimica; Colnago, Luiz Alberto, E-mail: colnago@cnpdia.embrapa.br [Embrapa Instrumentacao, Sao Carlos, SP (Brazil)

    2012-07-01

    Nuclear magnetic resonance (NMR) is one of the most versatile analytical techniques for chemical, biochemical and medical applications. Despite this great success, NMR is seldom used as a tool in industrial applications. The first application of NMR in flowing samples was published in 1951. However, only in the last ten years Flow NMR has gained momentum and new and potential applications have been proposed. In this review we present the historical evolution of flow or online NMR spectroscopy and imaging, and current developments for use in the automation of industrial processes. (author)

  11. Study on radiographic and minerals characteristics of renal calculus; Estudo das caracteristicas radiograficas e minerais de calculos renais

    Energy Technology Data Exchange (ETDEWEB)

    Fernandes, Marco A.R., E-mail: mfernandes@fmb.unesp.b [Universidade Estadual Paulista Julio de Mesquita Filho (FMB/UNESP), Botucatu, SP (Brazil). Fac. de Medicina. Dept. de Dermatologia e Radioterapia; Goldberg, Jose [Universidade Estadual Paulista Julio de Mesquita Filho (FMB/UNESP), Botucatu, SP (Brazil). Fac. de Medicina. Dept. de Urologia; Sakate, Makoto [Universidade Estadual Paulista Julio de Mesquita Filho (FMB/UNESP), Botucatu, SP (Brazil). Fac. de Medicina. Dept. de Doencas Tropicais e Diagnostico por Imagem; Louzada, Mario J.Q. [Universidade Estadual Paulista Julio de Mesquita Filho (UNESP), Aracatuba, SP (Brazil). Curso de Medicina Veterinaria; Fernandes, Marco F.S. [Santa Casa de Misericordia de Sao Jose do Rio Preto, SP (Brazil). Dept. de Cirurgia Geral

    2010-07-01

    Radiological Images of kidneys stones were analyzed, quantifying the optical density (D.O.) and the blackening degree in the radiographic film of the samples. Studies of the literature, analyses of samples and interviews with specialists of the Center of Sciences and Technologies of Materials (CCTM) of the Institute of Energy and Nuclear Researches (IPEN/CNEN-SP), after crystallographic analysis for absorption techniques and diffraction of ray-X, showed that D.O. of the stones it is more directly dependent of their dimensions of what of their contents concentration. It is the researchers' consensus that as larger D.O. of the radiographic image of the calculation renal, larger her density (g/cm{sup 3}) and therefore larger the importance of the application of an appropriate energy for the fragmentation of the calculation. This energy, supplied by the equipment extracorporeal shock wave lithotripsy (ESWL) it depends on several parameters inside the ones which the anatomy and the patient's position and of the own limitations of the lithotripsy equipment. This interpretation, at least for the analyzed samples, it disappoints a simplistic correlation among the parameters of the shock waves used in the lithotripsy procedures and the measures of D.O. and characteristics minerals. Another restriction factor is the discrepancy of the radiological image the kidneys stones camped in the patient, surrounded by the organs and interposed bone structures, and gotten her through the analysis of the fragments expelled after the accomplishment of ESWL, which present great variety of granulations. (author)

  12. Efecto de la concentracion de hidrogeno en la red de hierro bcc por calculos ab-initio

    OpenAIRE

    Sánchez, Javier; Andres, P.L. de; Fullea, J., Linares, P.,; Andrade, C

    2008-01-01

    Utilizando cálculos mecano-cuánticos de primeros principios hemos estudiado la interacción del hidrógeno con la red cúbica centrada en el cuerpo del hierro. El hidrógeno intersticial puede ocupar dos posiciones de alta simetría en la red: el hueco octaédrico y el tetraédrico. Nuestros cálculos nos proporcionan barreras de difusión entre ambos huecos, que analizamos para entender la propagación del hidrogeno a través de la red de hierro. Se ha estudiado el efecto de la concentración de hidróge...

  13. Calculation of the Doppler broadening function using Fourier analysis;Calculo da funcao de alargamento Doppler utilizando analise de Fourier

    Energy Technology Data Exchange (ETDEWEB)

    Goncalves, Alessandro da Cruz

    2010-07-01

    An efficient and precise method for calculation of Doppler broadening function is very important to obtain average group microscopic cross sections, self shielding factors, resonance integrals and others reactor physics parameter. In this thesis two different methods for calculation of Doppler broadening function and interference term will be presented. The main method is based on a new integral form for Doppler broadening function {psi}(x,{zeta}) which gives a mathematical interpretation of the approximation proposed by Bethe and Placzek, as the convolution of the Lorentzian function with a Gaussian function. This interpretation besides leading to a new integral form for {psi}(x,{zeta}), enables to obtain a simple analytic solution for the Doppler broadening function. (author)

  14. RAMA Methodology for the Calculation of Neutron Fluence; Metodologia RAMA para el Calculo de la Fluencia Neutronica

    Energy Technology Data Exchange (ETDEWEB)

    Villescas, G.; Corchon, F.

    2013-07-01

    he neutron fluence plays an important role in the study of the structural integrity of the reactor vessel after a certain time of neutron irradiation. The NRC defined in the Regulatory Guide 1.190, the way must be estimated neutron fluence, including uncertainty analysis of the validation process (creep uncertainty is ? 20%). TRANSWARE Enterprises Inc. developed a methodology for calculating the neutron flux, 1,190 based guide, known as RAMA. Uncertainty values obtained with this methodology, for about 18 vessels, are less than 10%.

  15. Calculo Preliminar de la Tasa de Meteorización del Batolito Antioqueño, Cordillera Central, Colombia

    Directory of Open Access Journals (Sweden)

    Carolina Garcia

    2004-12-01

    Full Text Available Este trabajo es una estimación preliminar del tiempo necesario para generar la espesa capa de saprolito que caracteriza el perfil de meteorización actual de un batolito cuarzodiorítico cretácico que aflora en altiplanos de la Cordillera Central de Colombia, entre 5º50' y 7º00' de latitud Norte y 74º50' y 75º35' de longitud Oeste y a alturas entre 750 y 2700 m.Se utilizan datos obtenidos previamente mediante el análisis de la composición química de las aguas superficiales de cuatro cuencas con áreas diferentes, ubicadas sobre el Batolito Antioqueño, al este de Medellín. Los cáculos se hicieron con el método basado en la pérdida de componentes en solución utilizando diferentes valores de solutos. Al utilizar la pérdida de sílice se obtiene un tiempo de meteorización de unos 6 x 10 6 años, comparable con el obtenido mediante la datación de las cenizas volcánicas mas antiguas que recubren la topografía actual y que indican la fecha mínima de configuración de la superficie de erosión.A pesar de resultar de una serie de suposiciones simplificadoras, este resultado es interesante y justifica la realización de determinaciones mas detalladas. Confirma la larga preservación de superficies de erosión antiguas conformadas sobre un saprolito que desde hace varios millones de años no ha sido sometido a una erosión profunda, fenómeno poco común en una zona tectónicamente activa como la estudiada.

  16. Estimations of internal dosimetry: practical calculations of incorporated activity; Estimaciones de dosimetria interna: calculos practicos de actividad incorporada

    Energy Technology Data Exchange (ETDEWEB)

    Cortes C, A. [CNSNS, Dr. Barragan 779, 03020 Mexico D.F. (Mexico)

    2003-07-01

    The National Commission of Nuclear Security and Safeguards (CNSNS) carries out periodically measurements of corporal activity to Occupationally Exposed Personnel (POE) to determine that the received doses are in according to that settled down in the General Regulation of Radiological Security. In this work the results of the incorporated activity estimates starting from the results of the measurements that were carried out in the one CNSNS laboratory are presented, with which it should be determine lastly the internal dose. Its were used different methodologies to estimate the incorporated activity: estimate with isolated data, estimate with global data and method of the best estimate, demonstrating this last to be the more appropriate to determine the internal dose. (Author)

  17. Elements for the calculation of reactive power compensation (I); Elementos para o calculo de compensacao de energia reativa (I)

    Energy Technology Data Exchange (ETDEWEB)

    Braun, Mathias [Lippstadt (Germany)

    2010-07-15

    This paper presents a resume of the practical experiences for use in technical calculations. The author intends to avoid that the trainee professionals be oriented to the extensive of the tables, dispensing the electrotechnical fundamentals. The calculation is step by step developed and followed by conceptual explanation. This article will be published into two parts, being this part the first one to be presented.

  18. Manual method for dose calculation in gynecologic brachytherapy; Metodo manual para o calculo de doses em braquiterapia ginecologica

    Energy Technology Data Exchange (ETDEWEB)

    Vianello, Elizabeth A.; Almeida, Carlos E. de [Instituto Nacional do Cancer, Rio de Janeiro, RJ (Brazil); Biaggio, Maria F. de [Universidade do Estado, Rio de Janeiro, RJ (Brazil)

    1998-09-01

    This paper describes a manual method for dose calculation in brachytherapy of gynecological tumors, which allows the calculation of the doses at any plane or point of clinical interest. This method uses basic principles of vectorial algebra and the simulating orthogonal films taken from the patient with the applicators and dummy sources in place. The results obtained with method were compared with the values calculated with the values calculated with the treatment planning system model Theraplan and the agreement was better than 5% in most cases. The critical points associated with the final accuracy of the proposed method is related to the quality of the image and the appropriate selection of the magnification factors. This method is strongly recommended to the radiation oncology centers where are no treatment planning systems available and the dose calculations are manually done. (author) 10 refs., 5 figs.

  19. Componentes Principales (C.P. de los sistemas de calculo del IPC base 92 y sistema IPC base 2001

    Directory of Open Access Journals (Sweden)

    Julio Pallas González

    2002-01-01

    Full Text Available Nueve años después de que se adoptara un cambio de base en el cálculo del IPC para el Estado Español, asistimos a un cambio de sistema en el cálculo del mismo, naciendo el sistema de índices de precios, base 2001. A lo largo de este trabajo y utilizando el programa estadístico SPSS, se tratará de realizar un análisis multivariante, sobre las distintas variables que componen el IPC base 92, del estado español, y las del índice, atendiendo al nuevo sistema base 2001, que entró en vigor en enero de 2002. De todas las técnicas multivariantes susceptibles de ser aplicadas en este trabajo, se utilizaran el análisis de componentes principales y el análisis factorial, con el fin de obtener factores no observables que permitan explicar, perdiendo la mínima información, las variables originales que representan.

  20. NAVEGABILIDAD Y CAPACIDAD DE CARGA DE UN NAVÍO PESQUERO: CALCULOS POR MEDIO DE COMPUTADORAS PERSONALES

    OpenAIRE

    Murillo B, Luis Manuel

    2011-01-01

    Se introducen procedimientos nu,éricos para el cálculo de algunas de las curvas hidrostáticas del diseño naval. Los procedimientos usan dibujo ayudado por computadora (CAD) y ho9jas de cálculo modernas. El uso de las computadoras agiliza grandemente los procedimientos tradicionales y permite al diseñador concentrarse en los principios del diseño más que en los detalles del cálculo tedioso. Los procedimientos son aplicables a pequeños de pesaca comunmente observados en las costas centroamerica...

  1. Aplicação de metodos de otimização para o calculo do equilibrio termodinamico

    OpenAIRE

    Alexandre Teixeira de Souza

    2004-01-01

    Resumo: O conhecimento do equilíbrio de fases, com ou sem reações químicas simultâneas, é de grande importância no projeto e análise de uma grande variedade de operações de processos químicos, incluindo reatores e unidades de separação. Devido à natureza nãoconvexa e não-linear de modelos termodinâmicos, necessários para descrever o problema do equilíbrio químico e/ou de fases, há um grande interesse na aplicação de técnicas de otimização mais seguras e robustas para descrever o comportamento...

  2. Elementary computation of radiation doses and shieldings for radiochemical laboratories; Calculo Elemental de dosis y blindajes para laboratorios radioquimicos

    Energy Technology Data Exchange (ETDEWEB)

    Jimeno de Osso, F.

    1971-07-01

    Simple procedures for the calculation of radiation exposition, half thickness, shield thickness, etc. are described and equations and graphs are included for those gamma-emitting radionuclides, that are more often used in radiochemical laboratories. Application is made of these procedures to three radionuclides, bromine-82, sodium-24 and cobalt-60 which cover a rather wl.de energy range; theoretical results are compared with those obtained from experimental measurements. (Author) 23 refs.

  3. Introduction to energy balance of biomass production; Introduccion al calculo del balance energetico de la produccion de Biomasa

    Energy Technology Data Exchange (ETDEWEB)

    Manzanares, P.

    1997-11-01

    During last years, energy crops have been envisaged as an interesting alternative to biomass residues utilization as renewable energy source. In this work, main parameters used in calculating the energy balance of an energy crop are analyzed. The approach consists of determining energy equivalents for the different inputs and outputs of the process, thus obtaining energy ratios of the system, useful to determine if the energy balance is positive, that is, if the system generates energy. Energy costs for inputs and assessment approaches for energy crop yields (output) are provided. Finally, as a way of illustration, energy balances of some representative energy crops are shown. (Author) 15 refs.

  4. The cost calculus model for the hull roughness; Um modelo para calculo do custo da rugosidade do casco

    Energy Technology Data Exchange (ETDEWEB)

    Marco, Antonino Di [International Paint (Akzo Nobel Ltda.), Sao Paulo, SP (Brazil)

    2004-07-01

    The economic importance of the condition of the immersed hull cannot be underestimated; any increase of the roughness may result in a significant increase in the operational costs of a ship. There are two main types of roughness, biological and physical, each one with its proper characteristics of macro and micro roughness; when an increase in the roughness of the underwater hull occurs, the frictional resistance of the ship or .drag. also increases, resulting in additional power and consequent increase of the fuel consumption to keep the speed of the ship. Keeping the power constant will result in lower speed and greater voyage times. Aiming the better understanding of the effect of the roughness in the performance, costs and operational efficiency of a ship, International Paint developed a new model called 'Hull Roughness Penalty Calculator', a program that predicts the increase of the hull roughness during in service time specified service and combines it with the fouling risk associated with different types of antifoulings. The model compares fuel consumptions and costs of different types of TBT free antifoulings to derive the potential benefit, and also can be used to compare the emissions of carbon dioxide and sulphur oxides. (author)

  5. Calculation of sensitivities in electrical systems with SIFLETCA devices; Calculo de sensibilidades en sistemas electricos con dispositivos SIFLETCA

    Energy Technology Data Exchange (ETDEWEB)

    Rubio Marroquin, Gabriel Omar

    2004-03-15

    With the purpose of avoiding the installation of new transmission lines, some researches have proposed the installation of SIFLETCA devices. Therefore in this thesis, different models in steady state of diverse SIFLETCA devices are described, such as: compensator variable series (VSC), static compensator of VArs (SCV), transformer phase shifter (TPS), transformer with changer under load (TWCL) and the universal controller of power flows (UCPF). In addition, it is developed in this thesis the equations used in the Jacobean of the method Newton-Raphson, to solve power flows including SIFLETCA devices. The different applications that are obtained when installing a device, such as prevention of flows in ring, electronic barrier, increment in the transmission capacity and specification of the power flow in transmission lines. On the other hand in the thesis, an analysis of sensitivities of a power system in steady state is developed. Also the control parameters are proposed in the thesis for which the sensitivities are calculated. Also, a performance index is used to measure the degree of congestion of an electrical system. In calculating the sensitivities the obtained results of the power flows are utilized. Four electrical networks are used to find where each SIFLETCA device must be located to reduce the congestion in the system. Also, the method developed in the thesis is compared with a method of sensitivities that uses DC flows, for validation and to show the advantages of using the Newton method in power flows. [Spanish] Con el fin de evitar instalar nuevas lineas de transmision, algunos investigadores han propuesto la instalacion de los dispositivos SIFLETCA. Por lo tanto en esta tesis, se describe diferentes modelos en estado estacionario de diversos dispositivos SIFLETCA, siendo: compensador serie variable (CSV), compensador estatico de VArs (CEV), transformador desfasador (TD), transformador con cambiador bajo carga (TTC) y el controlador universal de flujos de potencia (CUFP). Ademas, se desarrolla en esta tesis las ecuaciones utilizadas en el Jacobiano del metodo Newton-Raphson, para resolver flujos de potencia incluyendo los dispositivos SIFLETCA. Se muestra diferentes aplicaciones que se tienen al instalar un dispositivo, tales como prevencion de flujos en anillo, barrera electronica, incremento en la capacidad de transmision y especificacion del flujo de potencia en lineas de transmision. Por otra parte, se desarrolla en la tesis un analisis de sensibilidades de un sistema de potencia en estado estacionario. Tambien se proponen en la tesis los parametros de control para los cuales se calcula las sensibilidades. Asimismo, se utiliza un indice de desempeno para medir el grado de congestion de un sistema electrico. Al calcular las sensibilidades se utiliza los resultados obtenidos de los flujos de potencia. Se usa 4 redes electricas para encontrar donde se debe situar cada dispositivo SIFLETCA para reducir la congestion en el sistema. Tambien, se compara el metodo desarrollado en la tesis con un metodo de sensibilidades que emplea flujos de CD para validacion y mostrar las ventajas de usar el metodo Newton en flujos de potencia.

  6. Criticality calculation of the nuclear material warehouse of the ININ; Calculo de criticidad del almacen del material nuclear del ININ

    Energy Technology Data Exchange (ETDEWEB)

    Garcia, T.; Angeles, A.; Flores C, J., E-mail: teodoro.garcia@inin.gob.mx [ININ, Carretera Mexico-Toluca s/n, 52750 Ocoyoacac, Estado de Mexico (Mexico)

    2013-10-15

    In this work the conditions of nuclear safety were determined as much in normal conditions as in the accident event of the nuclear fuel warehouse of the reactor TRIGA Mark III of the Instituto Nacional de Investigaciones Nucleares (ININ). The warehouse contains standard fuel elements Leu - 8.5/20, a control rod with follower of standard fuel type Leu - 8.5/20, fuel elements Leu - 30/20, and the reactor fuel Sur-100. To check the subcritical state of the warehouse the effective multiplication factor (keff) was calculated. The keff calculation was carried out with the code MCNPX. (Author)

  7. Estudo e comparação de tres diferentes metodos para calculo de pressão de vapor

    OpenAIRE

    Themis Coelho Borges Lima

    1997-01-01

    Resumo: São estudados neste trabalho, três métodos para cálculo de pressão de vapor. O primeiro procedimento consiste em ajustar os parâmetros das equações de Antoine, de Wagner e do DIPPR, calculadas por regressão de pressões de vapor experimentais, utilizando o método de minimização não-linear de Marquardt. Na equação de Wagner, a pressão crítica é considerada um parâmetro ajustável, obtendo seus valores para algumas substâncias, a partir de dados experimentais. As pressões de vapor calcula...

  8. Method to calculate failure rate of submarine flexible pipes; Metodo para calculo da taxa de falha de dutos flexiveis submarinos

    Energy Technology Data Exchange (ETDEWEB)

    Simoes Filho, Salvador [PETROBRAS S.A., Rio de Janeiro, RJ (Brazil)

    2003-07-01

    This report presents calculation method for failure rate of submarine flexible pipes in PETROBRAS using the distribution of Weibull in comparison with the traditional method of PARLOC that uses the exponential distribution. PARLOC - Pipeline and Riser Loss of Containment Study - Pipeline Offshore Reliability Data - database of pipes of the North Sea. (author)

  9. Methods of calculus for neutron spectrometry in proportional counters; Metodos de calculo para espectrometria de neutrones en contadores proporcionales

    Energy Technology Data Exchange (ETDEWEB)

    Butragueno, J. L.; Blazquez, J. B.; Barrado, J. M.

    1976-07-01

    Response functions for cylindrical proportional counters with hydrogenated gases have been determined, taking in account only wall effect, by means of two independent calculus methods. One of them is a Monte Carlo application and the other one analytica at all. Results of both methods have been compared. (Author)

  10. Elementary computation of radiation doses and shieldings for radiochemical laboratories; Calculo Elemental de dosis y blindajes para laboratorios radioquimicos

    Energy Technology Data Exchange (ETDEWEB)

    Jimeno de Osso, F.

    1971-07-01

    Simple procedures for the calculation of radiation exposition, half thickness, shield thickness, etc. are described and equations and graphs are included for those gamma-emitting radionuclides, that are more often used in radiochemical laboratories. Application is made of these procedures to three radionuclides, bromine-82, sodium-24 and cobalt-60 which cover a rather wl.de energy range; theoretical results are compared with those obtained from experimental measurements. (Author) 23 refs.

  11. CALCULO DE PARAMETROS DETERMINANTES EN LA PREPARACION DE UN CIRCUITO DE VENTILACION EN MINERIA SUBTERRANEA DE CARBON USANDO PROGRAMACION ESTRUCTURADA

    National Research Council Canada - National Science Library

    JORGE LUIS KERGUELEN BENDECK; VICTOR ALFONSO GONZÁLEZ MARTÍNEZ; JOVANI ALBERTO JIMÉNEZ BUILES

    2013-01-01

    ... energética y por encontrarse de forma abundante en la corteza terrestre, sino por los riesgos que ponen en peligro la vida y el bienestar de los trabajadores en la explotación subterránea del mineral...

  12. Precise magnetostatic field using the finite element method; Calculo de campos magnetostaticos com precisao utilizando o metodo dos elementos finitos

    Energy Technology Data Exchange (ETDEWEB)

    Nascimento, Francisco Rogerio Teixeira do

    2013-07-01

    The main objective of this work is to simulate electromagnetic fields using the Finite Element Method. Even in the easiest case of electrostatic and magnetostatic numerical simulation some problems appear when the nodal finite element is used. It is difficult to model vector fields with scalar functions mainly in non-homogeneous materials. With the aim to solve these problems two types of techniques are tried: the adaptive remeshing using nodal elements and the edge finite element that ensure the continuity of tangential components. Some numerical analysis of simple electromagnetic problems with homogeneous and non-homogeneous materials are performed using first, the adaptive remeshing based in various error indicators and second, the numerical solution of waveguides using edge finite element. (author)

  13. Equações de estado não cubicas : aplicação em calculos de processo

    OpenAIRE

    Rita Maria de Brito Alves

    1998-01-01

    Resumo: Este trabalho apresenta a avaliação de duas equações de estado não cúbicas, as equações PHCT e SUZUKI, em relação aos seus desempenhos em cálculos de equili'brio líquido-vapor (EL V) para projeto e simulação de processo. A complexa equação PHCT original é adequada para representar EL V de misturas binárias e multicomponentes de hidrocarbonetos leves e pesados na faixa de temperatura e pressão normalmente encontrada em processos petroquímicos. Entretanto, a escassez de extensas tabelas...

  14. Experimental method for calculation of effective doses in interventional radiology; Metodo experimental para calculo de dosis efectivas en radiologia intervencionista

    Energy Technology Data Exchange (ETDEWEB)

    Herraiz Lblanca, M. D.; Diaz Romero, F.; Casares Magaz, O.; Garrido Breton, C.; Catalan Acosta, A.; Hernandez Armas, J.

    2013-07-01

    This paper proposes a method that allows you to calculate the effective dose in any interventional radiology procedure using an anthropomorphic mannequin Alderson RANDO and dosimeters TLD 100 chip. This method has been applied to an angio Radiology procedure: the biliary drainage. The objectives that have been proposed are: to) put together a method that, on an experimental basis, allows to know dosis en organs to calculate effective dose in complex procedures and b) apply the method to the calculation of the effective dose of biliary drainage. (Author)

  15. Nueva formula matemática para el calculo de la proteinuria de 24 horas en niños

    Directory of Open Access Journals (Sweden)

    José R. Salabarría

    1996-08-01

    Full Text Available Se elaboró una fórmula matemática para la cuantificación de la excreción urinaria de proteínas en 24 horas en niños y adolescentes, derivada de la relación proteinuria creatinuria (RPC. Se procesaron 104 muestras de orina de 24 horas, las cuales se dividieron en 2 grupos de acuerdo con la excreción diaria de creatinina. La proteinuria de 24 horas se determinó en cada grupo por el método tradicional y mediante la fórmula propuesta. Se obtuvo una excelente correlación (r = 0,994 y una elevada concordancia en el grupo con recolecciones adecuadas de orina, no así en el grupo con recolecciones inadecuadas (r = 0,896. Al comparar las RPC en 30 muestras de orina obtenidas en 3 diferentes períodos, con la RPC de 24 horas correspondiente se obtuvo una elevada correlación (r 0,99; no obstante la que guardó mayor identidad fue la del período comprendido entre las 7:00 a.m. y 12:00 m.A mathematical formula for the quantification of 24-hour urinary protein excretion in children and adolescents, derived from the proteinuria-creatinuria relation (PCR was elaborated. 104 urine specimens were processed and divided into two groups according to daily creatinine excretion. 24-hour proteinuria was determined in each group by the traditional method and by the formula proposed. An excelent correlation (r=0,994 and an elevated correspondence in the group with adequate urine collections were obtained, but it was not so in the group with inadequate collections (r=0,896. On comparing the PCR in 30 urine specimens collected at three different periods with the corresponding 24-hour PCR, an elevated correlation (r 0,99 was obtained; however, the one with the greatest identity was that collected between 7:00 a.m. and 12:00 m.

  16. Calculation of absorbed dose in water by chemical Fricke dosimetry; Calculo de dose absorvida na agua por dosimetria quimica Fricke

    Energy Technology Data Exchange (ETDEWEB)

    Rodrigues, Adenilson Paiva, E-mail: adenilson-fisica@hotmail.com.br [Universidade do Estado do Rio de Janeiro (UERJ), Rio de Janeiro, RJ (Brazil); Meireles, Ramiro Conceicao [Fundacao do Cancer, Rio de Janeiro, RJ (Brazil)

    2016-07-01

    This work is the result of a laboratory activity performed in Radiological Sciences Laboratory (CRL), linked to the State University of Rio de Janeiro (UERJ). This practice aimed to determine the absorbed dose to water, through the primary calibration method called dosimetry Fricke, which consists of ferrous ions (Fe + 2) to ferric (Fe + 3), generated by water radiolysis products which is the structural change of water molecule caused by ionizing radiation. A spectrophotometer was used to extract data for analysis at a wavelength (λ) 304 and 224 nm with function of measuring the absorbance using bottles with irradiated and nonirradiated Fricke solution. (author)

  17. Consideraciones respecto al calculo de empalmes atornillados de perfiles estructurales de GFRP sometidos a flexión

    Directory of Open Access Journals (Sweden)

    Serna, Eduardo

    2003-06-01

    Full Text Available A composite material can be defined as the combination of two or more materials with the aim of obtaining a new product with improved properties. Composite materials, composed of a polymer matrix reinforced with fibers, are currently used as structural elements, in spite of the uncertainties on strength, deformability and durability. The use of pultruded profiles in shapes similar to those used in metallic construction, results in an interesting solution for this material when high resistance. protection against chemical attacks and lightness are required. The structural key point of those materials are the joints. The present paper is focused on joints composed of bolted plates on the wings of IPN pultruded profiles. Different tests conducted in LABEIN are described. Likewise, this paper deals with tests carried out with the purpose of analysing the feasibility of joints with high resistance bolts.Se entiende como material compuesto la combinación de dos o más materiales para obtener un nuevo producto que mejore las propiedades individuales de cada uno ellos. Se está comenzando a emplear el material compuesto. formado por una matriz de tipo polimérico o resina reforzada con fibras. como elementos estructurales. pero con reticencias originadas por las incertidumbres existentes en la actualidad relativas a su resistencia, deformabilidad y durabilidad. Este material aporta un importante interés cuando se quieren obtener elementos estructurales de alta resistencia . protección frente a ataques químicos y ligereza. utilizando perfiles a la manera de la estructura metálica. fabricados por pultrusión, Debido a que el punto crítico estructural se encuentra en las uniones. el presente artículo se centrará en los empalmes atornillados con cubrejuntas de alas de perfiles pultruídos IPN, describiendo los ensayos de diferente naturaleza realizados en las instalaciones del Centro Tecnológico LABEIN. A su vez se recogen los ensayos previos desarrollados para analizar la viabilidad de ejecutar uniones por rozamiento con tornillos de alta resistencia.

  18. Reação peritoneal tardia ao calculo biliar humano, de colesterol, deixado na cavidade abdominal de ratos

    Directory of Open Access Journals (Sweden)

    Luiz Carlos Bertges

    Full Text Available Foram avaliados os resultados tardios da colocação de cálculos biliares humanos, de colesterol, na cavidade peritoneal de ratos. Constituíram-se cinco grupos: cinco ratos foram apenas laparotomizados com manuseio da cavidade; cinco foram laparotomizados e receberam um ponto com fio monofilamentar cinco zeros no sulco paracólico direito e mesentério; dez receberam cálculos que foram deixados livres na cavidade peritoneal; em dez, os clculos foram fixados no sulco paracólico direito e, finalmente, dez tiveram clculos fixados no mesentério. Os animais foram mortos após cinco meses de pós-operatório quando se observou a cavidade abdominal e foi coletado material para estudo histopatológico. Concluiu-se que os cálculos não foram absorvidos, desenvolveram uma reação peritoneal do tipo corpo estranho com formação de plastrão e foram envolvidos por tecido fibroso e células inflamatórias.

  19. Calculo de tanque de PRFV de 200 000 litros de capacidad. // 200 000 liters capacity PRFV tank calculation.

    Directory of Open Access Journals (Sweden)

    J. García de la Figal Costales

    2002-01-01

    Full Text Available La tarea que se acomete es el cálculo a resistencia y rigidez de un tanque para el almacenamiento de agua, de 200 000 litrosde capacidad, construido de plástico reforzado con fibras de vidrio, PRFV. El mismo es cilíndrico vertical, de 8 metros dediámetro por 4.2 metros de altura. Los materiales seleccionados para la conformación de las láminas con las que se haránlos laminados de PRFV, fueron: resina poliéster isosftálica, y fibras de vidrio E.La carga fundamental a soportar por el tanque será la presión debida a la columna de agua en su interior, pero por estar a laintemperie y en zona de playa, se considerará también la acción de las dilataciones debidas a la temperatura, así como laacción de un ciclón.Palabras claves: resistencia, recipiente, composites, elementos finitos._____________________________________________________________________________Abstract.The stress and strains calculation of a water reinforced fiber glass container is carried out by means of a modern FiniteElement program, because the high complexity of calculus. The soported main load is the pressure caused by the column ofwater.Key words: Resistance, vessels, composites, finite elements.

  20. Contextualizacion y conceptualización de la planificación estratégica de la comunicación de marca aplicada al internal branding: propuesta de un modelo teorico

    OpenAIRE

    de la Guardia, Carlos

    2015-01-01

    Propósito de esta investigación: Saber cómo se está aplicando la planificación estratégica de la comunicación de marca a los empleados en los programas de internal branding y proponer un modelo teórico y una herramienta para facilitar su aplicación. Metodología: Se ha realizado, en primer lugar, una revisión documental retrospectiva y exploratoria de fuentes secundarias y, posteriormente, se han realizado catorce entrevistas en profundidad a expertos en Marketing y Recursos Humanos c...

  1. Theoretical thermodynamics analysis of cooling cycle bu advanced gas absorption using solar energy; Analisis teorico-experimental de un ciclo de refrigeracion por absorcion avanzado gax, operando con energia solar

    Energy Technology Data Exchange (ETDEWEB)

    Gomez, V. E.; Vidal, A. S.; Garcia, C. A.; Garcia-Valladares, O.; Best, R. B.; Hernandez, J. G.; Velazquez, N. L.

    2004-07-01

    In this article a solar system of refrigeration by absorption with heat exchange generator absorber (GAX) was analyzed. A theoretical thermodynamic analysis of the energetic behavior of the GAX absorption system was made. Experimental results were obtained with generation temperatures of 190 and 220 C, the evaporation temperature was set at 9 C and temperatures of cooling fluids (air and water) were set at 30 C and 28 C, respectively. It was possible to appreciate that the GAX effect decrease whether absorber, type falling film, is operated in option of parallel flow and it was increased when the absorber was operated in option of counterflow. (Author)

  2. Stability analysis of a recycling circuit of a BWR type reactor. Theoretical study; Analisis de estabilidad de un circuito de recirculacion de un reactor del tipo BWR. Estudio teorico

    Energy Technology Data Exchange (ETDEWEB)

    Salinas H, J.G.; Espinosa P, G. [Universidad Autonoma Metropolitana-Iztapalapa, 09000 Mexico D.F. (Mexico); Gonzalez M, V.M. [Comision Nacional de Seguridad Nuclear y Salvaguardias, 04000 Mexico D.F. (Mexico)

    2000-07-01

    The Technology, Regulation and Services Management of the National Commission of Nuclear Safety and Safeguards financed and in coordinate form with the I.P.H. Department of the Metropolitan Autonomous-Iztapalapa University developed the present project with the purpose of studying the effect of the recycling system on the linear stability of a BWR reactor whose reference central is the Laguna Verde power station. The present project forms part of a work series focused to the linear stability of the nuclear reactor of the Unit 1 at Laguna Verde power station. The components of the recycling system considered for the study of stability are the recycling external circuit (recycling pumps, valves) and the internal circuit (downcomer, jet pumps, lower full, driers, separators). The mathematical model is obtained applying mass balances and movement quantity in each one of the mentioned circuits. With respect to the nucleus model two regions are considered, the first one is made of a flow in one phase and the second one of a flow in two phases. For modelling the biphasic region it is considered homogenous flow. Generally it is studied the system behavior in the frequency domain starting from the transfer function applied to four operational states which correspond to the lower stability zone in the map power-flow of the Unit 1 of Laguna Verde power station. The Nyquist diagrams corresponding to each state as well as their characteristic frequency were determined. The results show that exists a very clear dependence of the power-flow relation on the stability of the system. It was found that the boiling length is an important parameter for the linear stability of the system. The obtained results show that the characteristic frequencies in unstability zones are similar to the reported data of the Unit 1 of the Laguna Verde power station in the event of power oscillations carried out in January 1995. (Author)

  3. RESGATANDO A MEMÓRIA DE AURORA DE AFONSO COSTA: UMA ABORDAGEM DE SUAS CONTRIBUIÇÕES TEORICO-PRÁTICAS PARA A ÁREA DA ENFERMAGEM

    OpenAIRE

    sabbadini da silva, lorena; UFF; soraia cavalcanti valente, Geilsa; UFF

    2010-01-01

    Autores: Lorena Sabbadini da Silva, Geilsa Soraia Cavalcanti Valente. Descritores: Enfermagem; História da enfermagem; Biografia. INTRODUÇÃO Entre o corpo acadêmico da Escola de Enfermagem Aurora de Afonso Costa é comum o sentimento de admiração pela personagem que lhe dá nome. Porém, ao tentarmos recuperar sua atuação profissional são encontradas diversas lacunas, sendo esta a motivação para este trabalho, conhecer mais sobre a história de Aurora e sobre o legado que construiu e que perman...

  4. L’esperienza della lettura in ottica cognitiva: un inquadramento teorico e un saggio di lettura di Mrs. Dalloway fra simulazione incarnata (embodied simulation e teoria della mente (theory of mind

    Directory of Open Access Journals (Sweden)

    Sara Boezio

    2014-05-01

    Full Text Available Scopo del presente lavoro è indagare il processo esperito da lettori di testi narrativi letterari in prosa. Ci si muoverà nell’ambito della narratologia cognitiva e, attingendo a recenti ricerche neuroscientifiche, ci si soffermerà in particolare su due nozioni: la nozione di ‘simulazione incarnata’, così come definita dal neurofisiologo Vittorio Gallese, membro dell’équipe che ha individuato i neuroni specchio, e la nozione di ‘teoria della mente’, elaborata in ambito filosofico e psicologico, di cui ha già cominciato a essere sondato il potenziale applicativo in campo letterario – seppur con alcuni limiti – da diversi narratologi, fra cui Lisa Zunshine e Alan Palmer. Verranno illustrati i capisaldi teorici di queste due nozioni, se ne mostreranno le divergenze e, infine, ne verrà testata l’efficacia attraverso l’analisi di alcuni brani tratti dal romanzo di Virginia Woolf Mrs. Dalloway. Emergerà come il meccanismo di simulazione incarnata alla base dell’‘embodied narratology’ si riveli uno strumento euristico fondamentale e necessario per integrare e completare la teoria della mente che, per quanto utile, non si dimostra in grado di spiegare la complessità dell’esperienza della lettura perché non rende conto del coinvolgimento corporeo che gli studi neuroscientifici hanno mostrato essere una componente di primaria importanza del nostro modo di interagire con gli altri nella realtà e, similmente, con le menti dei personaggi in un contesto finzionale.

  5. Estudo teorico das relações estrutura-atividade biologica de uma serie de derivados de chalcona (1,3-difenil-2propen-1-ona) como agentes anti-plasmodium falciparum (agentes antimalaricos)

    OpenAIRE

    Luiz Frederico Motta

    2004-01-01

    Resumo: O presente trabalho teve como objetivo investigar teoricamente as relações quantitativas entre estrutura química e atividade biológica (QSAR) de uma série de derivados de Chalcona (1,3-difenil-2-propen-1-ona). Os dados observados de atividade biológica correspondem à inibição in vitro da parasitemia ocasionada pelas cepas cloroquina-resistente de Plasmodium falcíparum, agente causador da malária. A primeira etapa da investigação consistiu em determinar a geometria molecular das estrut...

  6. Seguridad del paciente en Radioterapia Intraoperatoria: Impacto de los elementos controlados por el Radiofisico

    Science.gov (United States)

    Tarjuelo, Juan Lopez

    tambien se uso para estudiar la estabilidad de las camaras de ionizacion mencionadas. Se realizo la dosimetria in vivo en 45 pacientes con MOSFET reforzados mobile TN-502RDM-H, pelicula radiocromica Gafchromic MD-55-2, y se elaboro un modelo teorico para explicar los datos. Por ultimo, al precisarse el uso en RIO de la simulacion virtual y del calculo de la dosis absorbida en el paciente virtual, se ha ilustrado este apartado con la aceptacion y el estado de referencia inicial del planificador de tratamientos modulados con calculo de Monte Carlo Elekta Monaco. Para ello se utilizaron la camara de ionizacion TW31016-0104 y la matriz seven29 de PTW-Freiburg, pelicula radiocromica Gafchromic EBT-2, y diferentes maniquies. Resultados: El FMEA identifico 57 modos de fallo y efectos potenciales. No se experimentaron sucesos relativos a una administracion inadecuada de la dosis absorbida. Se identificaron las revisiones dobles y por un par como claves para reducir los riesgos asociados al equipo de profesionales involucrado en la RIO. Se identificaron tambien oportunidades de mejora con el uso de la automatizacion y el enclavamiento. En cuanto al SPC, los indices de capacidad del proceso abarcaron de 1,6 a 9,3 para un nivel de especificaciones del +/-2%. Las intervenciones simuladas alcanzaron del 2% al 34% de las sesiones de medida. Las camaras de ionizacion Farmer derivaron en direcciones opuestas en un periodo de 6 anos; aunque ello no se aprecio en los informes de calibracion del laboratorio acreditado. No derivo la camara PPC-40. En la dosimetria in vivo, las medidas de los MOSFET no se desviaron significativamente de las medidas con pelicula. Los valores centrales de las dosis absorbidas quedaron entre la dosis absorbida prescrita y la maxima, con lo que indicaron un tratamiento correcto del lecho tumoral. Las anchuras de los intervalos de confianza de las dosis absorbidas esperadas segun el modelo teorico al nivel del 95% abarcaron del 8,6% al 14,7%. Las verificaciones de

  7. Influencia de la infraestructura bibliotecaria en el desarrollo de produccion cientifica en universidades mexicanas inmersas en procesos de acreditacion

    National Research Council Canada - National Science Library

    Murguia Jaquez, Laura Patricia; Tarango Ortiz, Javier; Romo Gonzalez, Jose Refugio; Ascencio Baca, Gerardo

    2013-01-01

    .... Este artfculo, a partir de la integracion de un modelo teorico simplificado, analiza el comportamiento que observan docentes e investigadores de 33 universidades mexicanas que han experimentado algun...

  8. La pedagogia critica y las competencias de emprededurismo en estudiantes universitarios

    National Research Council Canada - National Science Library

    Viera, Aixa; Perez, Ariene; Paredes, Maria

    2008-01-01

    .... Los aportes realizados desde la empiria mediante la ejecucion de procesos de intervencion asistida durante cuatro semestres son contrastados con los referentes teoricos de la pedagogia critica...

  9. La adaptacion como atributo esencial en el fomento de sistemas agropecuarios resilientes ante las perturbaciones

    National Research Council Canada - National Science Library

    Nahed Toral, Jose; Palma Garcia, Jose Manuel; Gonzalez Garcia, Eliel

    2014-01-01

    El presente trabajo tuvo como objetivo documentar algunos fundamentos teoricos del enfoque de sistemas y de la adaptacion como atributo primordial para conseguir sistemas agropecuarios resilientes y sostenibles...

  10. Flow Resistance in Open Channels and Limits of Applicability of Manning's Formula; Resistencia al flujo en canales y limites de aplicabilidad de la formula de manning

    Energy Technology Data Exchange (ETDEWEB)

    Aldama, Alvaro A; R Ocon, Afredo [Instituto Mexicano de Tecnologia del Agua, Jiutepec, Morelos (Mexico)

    2002-03-01

    The concepts involved in the estimation of flow resistance in open channels are reviewed. In particular, of expressions for the friction factor that allow the derivation of expressions for the friction factor that appears in Darcy-Weisbach's formula for circular channels flowing full or at a depth equal half the diameter, and for wide channels, conveying hydraulically rough, fully turbulent flow. The results of such analyses show that it is possible to avoid adjustments to the numerical values that appear in Colebrook's formula, in order to reproduce experimental data. They also make it possible to explain the empirical dispersion observed in the values of the parameters of an expression used to estimate the Darcy-Weisbach friction coefficient for wide channels. On the basis of these results, the range of validity for Manning's formula is determined. Finally, additional evidence is provided in the estimation of flow resistance in open channels, being well represented by the hydraulic radius alone. This observation allows to foresees the possibility of developing a universally valid formula for the Darcy-Weisbach friction factor, applicable to flow in open channels. [Spanish] Se revisan los conceptos involucrados en la estimacion de la resistencia al flujo en canales. En particular, se senalan los inconvenientes de la popular formula de Manning. Tambien se presentan analisis teoricos que permiten determinar expresiones para el factor de friccion de la formula de Darcy-Weisbach para canales circulares trabajando llenos a la mitad, y para canales anchos conduciendo flujo hidraulicamente rugoso con turbulencia desarrollada. Se demuestra que los resultados de dichos analisis permiten evitar hacer ajustes en los valores numericos que aparecen en la formula de Colebrook, a fin de reproducir observaciones experimentales. Asimismo, hacen posible explicar la dispersion experimental en los valores de los parametros que aparecen en una expresion para el calculo

  11. NMR study of quasi-one-dimensional itinerant-electron magnets RMn4Al8 ( R=Y, Lu and Sc)

    Science.gov (United States)

    Muro, Y.; Nakamura, H.; Kohara, T.

    2008-04-01

    55Mn-NMR measurements, which revealed previously the presence of spin pseudogap in YMn 4Al 8, have been extended to LuMn 4Al 8 and ScMn 4Al 8. Temperature ( T) dependences of the Knight shift, K, and the nuclear spin-lattice relaxation rate, 1/T1, are well explained by the same pseudogap model used to explain a broad maximum observed in the T-dependence of the susceptibility, indicating common nature in the spin excitation spectrum in the quasi-one-dimensional itinerant-electron compounds.

  12. YMn2Hx and RMn(2-y)Fe(y)H6 (R = Y, Er) studied by Raman, infrared and inelastic neutron scattering spectroscopies.

    Science.gov (United States)

    Paul-Boncour, V; Parker, S F; Hagemann, H; Filipek, S M; Wierzbicki, R; Latroche, M

    2011-01-01

    YMn2 forms either interstitial YMn2Hx hydrides for x < or = 4.5 or a complex YMn2H6 hydride when submitted to high hydrogen pressure. These compounds have been studied by inelastic neutron scattering (INS) in order to clarify the different modes of H vibration. The INS spectra of YMn2Hx hydrides are strongly dependent on the H content. YMn2H6 and YMn2D6 show broad bands, also observed by Raman and IR spectroscopy, assigned to H-Mn-H (or D) and Mn-H bending and stretching modes. Both ErMn2D6 and ErMn1.8Fe0.2D6 show, in addition to the H vibration mode, an intense band at 215 cm(-1) which has been attributed to a magnetic excitation of Er3+ in view of its momentum transfer dependence.

  13. USO DA RMN DE BAIXA RESOLUÇÃO NA AVALIAÇÃO DA DINÂMICA MOLECULAR DO Origanum vulgare

    Directory of Open Access Journals (Sweden)

    Vanessa Cristina dos Santos Peixoto de Oliveira

    2015-03-01

    Full Text Available In this work, proton NMR relaxometry was used to measure the behavior of spin-lattice relaxation time with T1H as the time constant, and also of spin-spin relaxation time with the time constant T2H. These relaxometry parameters were determined to better understand the changes in the main structures present in commercial and in nature forms of origanum. The T1H relaxation data showed that the structures which had higher molecular mass were more sensitive to degradation with increased temperature treatment. According to the values of the T2H parameter, up to 150 degrees no significant change in the mobility and organization of water was observed. These data infer that the ideal cooking temperature and tea preparation mode for this herb should be around 100 degrees for the sample not to lose its characteristics. Also, it is not advisable to cook this herb at higher than 150 degrees but better to consume it at room temperature, especially give commercial herb has already been dehydrated.

  14. Identification de filtres solaires dérivés de l'acide para-aminobenzoique par spectroscopie RMN et par CPG/SM.

    Science.gov (United States)

    Masse, M O; Delporte, C; Bervelt, E

    2001-10-01

    Gas chromatography coupled with mass spectrometry and protonic nuclear magnetic resonance used directly or on fractions obtained by preparative thin layer chromatography, allow identification of the main molecule in commercial samples of PABA (Cas RN 150-13-0), PEG-25 PABA (Cas RN 116242-27-4), glyceryl PABA (Cas RN136-44-7), ethyl dihydroxypropyl PABA (Cas RN 58882-17-0) or octyl dimethyl PABA (Cas RN 21245-02-3).

  15. Aplicación y nuevos desarrollos de la espectroscopía por RMN para el estudio de procesos de reconocimiento molecular entre carbohidratos y sus receptores

    OpenAIRE

    Berbís Moreno, Manuel Álvaro

    2016-01-01

    Los carbohidratos constituyen uno de los tipos de biomoléculas más complejos y ubicuos, cuyo reconocimiento por parte de receptores proteicos pertenecientes a diversas familias (lectinas, anticuerpos, enzimas y virus) determina una variedad de respuestas relacionadas con procesos fisiológicos y patológicos. El conocimiento, a nivel atómico, de la estructura de los carbohidratos y de sus interacciones con proteínas es esencial para una completa comprensión de muchos procesos vitales, así como ...

  16. Multilinear relations between {sup 13} C NMR chemical shifts of aliphatic halides; Relacoes lineares multiplas entre deslocamentos quimicos em RMN {sup 13} C de haletos alifaticos

    Energy Technology Data Exchange (ETDEWEB)

    Doyama, Julio Toshimi [UNESP, Botucatu, SP (Brazil). Inst. de Biociencias. Dept. de Quimica e Bioquimica; Tornero, Maria Teresinha Trovarelli [UNESP, Botucatu, SP (Brazil). Inst. de Biociencias. Dept. de Bioestatistica; Yoshida, Massayoshi [UNESP, Araraquara, SP (Brazil). Inst. de Quimica. Dept. de Quimica Organica

    1999-07-01

    The {sup 13} C NMR chemical shifts of the {alpha}, {beta}, {gamma} and {delta} carbons of 17 sets of aliphatic halides (F, Cl, Br and I), including mono, bi and tricyclic compounds, can be reproduced by a linear equation composed with two constants and two variables: {delta}{sub RX} = A{sup *} {delta}{sub R-X2}, where A and B are constants derived from multilinear regression of {sup 13} C chemical shifts observed; {delta}{sub R-X}, the chemical shifts of aliphatic halide (R-X); and {delta}{sub R-X1}, {delta}{sub R-X2} the chemical shifts of other halides. It was observed a better correlation for aliphatic bromides (R-X) by using data of aliphatic fluorides (R-X 1) and aliphatic iodides (R-X 2), resulting R{sup 2} of 0.9989 and average absolute deviation (AVG) of 0.39 ppm. For the chlorides (R-X), the better correlation was observed by using data of bromides (R-X 1) was observed better correlation with data of bromides (R-X 1) and iodides (R-X 2), R{sup 2} of 0.997 and AVG of 1.10 ppm. For the iodides (R-X) was observed better correlation with data of fluorides (R-X 1) and bromides (R-X 2), R{sup 2} of 0.9972 and AVG of 0.60 ppm. (author)

  17. NMR of proteins (4Fe-4S): structural properties and intramolecular electron transfer; RMN de proteines (4Fe-4S): proprietes structurales et transfert electronique intramoleculaire

    Energy Technology Data Exchange (ETDEWEB)

    Huber, J.G.

    1996-10-17

    NMR started to be applied to Fe-S proteins in the seventies. Its use has recently been enlarged as the problems arising from the paramagnetic polymetallic clusters ware overcome. Applications to [4Fe-4S] are presented herein. The information derived thereof deepens the understanding of the redox properties of these proteins which play a central role in the metabolism of bacterial cells. The secondary structure elements and the overall folding of Chromatium vinosum ferredoxin (Cv Fd) in solution have been established by NMR. The unique features of this sequence have been shown to fold as an {alpha} helix at the C-terminus and as a loop between two cysteines ligand of one cluster: these two parts localize in close proximity from one another. The interaction between nuclear and electronic spins is a source of additional structural information for (4Fe-AS] proteins. The conformation of the cysteine-ligands, as revealed by the Fe-(S{sub {gamma}}-C{sub {beta}}-H{sub {beta}})Cys dihedral angles, is related to the chemical shifts of the signals associated with the protons of these residues. The longitudinal relaxation times of the protons depend on their distance to the cluster. A quantitative relationship has been established and used to show that the solution structure of the high-potential ferredoxin from Cv differs significantly from the crystal structure around Phe-48. Both parameters (chemical shifts and longitudinal relaxation times) give also insight into the electronic and magnetic properties of the [4Fe-4S] clusters. The rate of intramolecular electron transfer between the two [4FE-4S] clusters of ferredoxins has been measured by NMR. It is far slower in the case of Cv Fd than for shorter ferredoxins. The difference may be associated with changes in the magnetic and/or electronic properties of one cluster. The strong paramagnetism of the [4Fe-4S] clusters, which originally limited the applicability of NMR to proteins containing these cofactors, has been proven instrumental in affording new information about the structural and kinetic properties of such proteins. (author).

  18. NMR study of the 1-{sup 13}C glucose colon bacterial metabolism; Etude du metabolisme bacterien colique du 1-{sup 13}C glucose par RMN

    Energy Technology Data Exchange (ETDEWEB)

    Briet, F.; Flourie, B.; Pochart, P.; Rambaud, J.C.; Desjeux, J.F. [Hopital Saint-Lazare, 75 - Paris (France); Dallery, L. [Conservatoire National des Arts et Metiers (CNAM), 75 - Paris (France); Grivet, J.P. [Centre National de la Recherche Scientifique (CNRS), 45 - Orleans-la-Source (France)

    1994-12-31

    The aim of the study is to examine in-vitro and by nuclear magnetic resonance the biological pathways for the fermentation of the 1-{sup 13}C labelled glucose (99 atoms percent) by human colon bacteria. The preparation of the bacterial suspension and the glucose degradation kinetics are presented; the NMR analysis sensitivity and quantification features are discussed and results are presented. 2 figs., 1 ref.

  19. [sup 13]C NMR on C[sub 60] single-crystal. RMN du [sup 13]C sur un monocristal de C[sub 60

    Energy Technology Data Exchange (ETDEWEB)

    Kerkoud, R.; Auban-Senzier, P.; Godard, J.; Jerome, D. (Paris-11 Univ., 91 - Orsay (France). Lab. de Physique des Solides); Lambert, J.M.; Bernier, P. (Montpellier-1 Univ., 34 (France))

    1994-01-01

    The authors report a [sup 13]C NMR study performed on a C[sub 60] single crystal (8% enriched in [sup 13]C) grown by sublimation. Molecular motions are tested by spin-lattice relaxation data and spectral shapes below and above the structural transition at T[sub c] = 262 K. The sharpness of this transition and the long relaxation times at low temperature, compared to previous data on powdered samples, confirm the high purity of the crystal.

  20. Far- and mid-infrared emission and reflection of magnetoelectric RMnO3 and RCrO3 (R =Rare Earth)

    Science.gov (United States)

    Massa, Nestor E.; Del Campo, Leire; de Sousa Meneses, Domingos; Echegut, Patrick; Martinez-Lope, Maria Jesus; Alonso, Jose Antonio

    2013-03-01

    Far- and mid-infrared emission and reflection spectra of ferrielectric hexagonal TmMnO3 show that small polarons, a paramagnetic collective electronic mode, and lower than TN soft hybrid modes are in concomitant relation. CO2 laser heating in dry air triggers oxidation and Mn3+- Mn4+ double exchange hopping conductivity. A collective excitation in the paramagnetic phase is assigned to eg electrons in THz low energy d-orbital fluctuations. It locks-in at the E-type antiferromagnetic onset (TN ~ 80K) into soft bands that harden simultaneously down to 4 K with temperature dependence given by the magnetic long range order coupling of the collective electric dipole. They have TN as critical temperature and critical exponents suggesting a second order phase transition. They also match zone center spin wave modes measured in isomorphous LuMnO3 (Lewtas et al, Phys. Rev. B 82, 184420 (2010)). Both excitations, magnons y electric dipoles, are generated by electrons eg in deformed d-orbitals. Sharing this behavior with orthorhombic NdMnO3 there is no evidence of new phonons in a structural deformation down to 4K Preliminary results in ErCrO3 (TN ~ 130 K) show the emerging soft bands in an order-disorder scenario. Overall, we conclude that magnetoelastic deformations in an orbital fluctuating environment are close related to magnetoelectric couplings.

  1. Absence of significant structural changes near the magnetic ordering temperature in small-ion rare earth perovskite RMnO3

    Science.gov (United States)

    Yu, T.; Tyson, T. A.; Chen, H. Y.; Abeykoon, A. M. M.; Chen, Y.-S.; Ahn, K. H.

    2014-12-01

    Detailed structural measurements on multiple length scales were conducted on a new perovskite phase of ScMnO3, and on orthorhombic LuMnO3 as a benchmark. Complementary density functional theory (DFT) calculations were carried out, and predict that ScMnO3 possesses E-phase magnetic order at low temperature with displacements of the Mn sites (relative to the high temperature state) of ˜0.07 Å, compared to ˜0.04 Å predicted for LuMnO3. However, detailed local, intermediate and long-range structural measurements by x-ray pair distribution function analysis, single crystal x-ray diffraction and x-ray absorption spectroscopy, find no local or long-range distortions on crossing into the low temperature E-phase of the magnetically ordered state. The measurements place upper limits on any structural changes to be at most one order of magnitude lower than DFT predictions and suggest that this theoretical approach does not properly account for the spin-lattice coupling in these oxides and may possibly predict the incorrect magnetic order at low temperatures. The results suggest that the electronic contribution to the electrical polarization dominates and should be more accurately treated in theoretical models.

  2. Magnetic and electronic orderings in orthorhombic RMnO3 (R=Tm, Lu) studied by resonant soft x-ray powder diffraction

    Science.gov (United States)

    Garganourakis, M.; Bodenthin, Y.; de Souza, R. A.; Scagnoli, V.; Dönni, A.; Tachibana, M.; Kitazawa, H.; Takayama-Muromachi, E.; Staub, U.

    2012-08-01

    Resonant soft x-ray powder diffraction experiments on orthorhombic TmMnO3 and LuMnO3 are presented. Experiments were performed in the vicinity of the Tm M5 and the Mn L2,3 edges to study the Tm and Mn magnetic moments, respectively. These experiments show that for the heavy rare-earth perovskite with an E-type ordered ground state, the Tm magnetic moments order already in the nonferroelectric incommensurate magnetic phase. Additionally, deviations from the collinear E-type Mn magnetic structure at low temperatures are found for both compounds. These experiments show the power of resonant soft x-ray diffraction, extended to polycrystalline 4f materials.

  3. Role of the apical oxygen in the low-temperature magnetoelectric effect in RMnO3 (R = Ho and Lu)

    Science.gov (United States)

    Vermette, J.; Jandl, S.; Orlita, M.; Gospodinov, M. M.

    2012-04-01

    Infrared active phonons of HoMnO3 and LuMnO3 single crystals are studied under an applied magnetic field below Ho3+ spin ordering at T=4.2 K. Interestingly, relatively strong mode energy shifts, induced by the magnetic field, are observed in HoMnO3 but are absent in the nonmagnetic rare-earth compound LuMnO3. We associate the large magnetoelectric effects in HoMnO3 with a mechanism of charge transfer between Ho3+ and apical oxygen. Also, the exact values of the published polarization change under the applied magnetic field are predicted with no adjustable parameters.

  4. Characterization of polyurethane/organophilic montmorillonite nanocomposites by low field NMR; Caracterizacao de nanocompositos de poliuretano/montmorilonita organofilica por RMN de baixo campo

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Marcos Anacleto da [Universidade Federal do Rio de Janeiro (UFRJ), RJ (Brazil). Laboratorio de Nanocompositos Polimericos; Tavares, Maria I.B.; Nascimento, Suelen A.M.; Rodrigues, Elton J. da R [Universidade Federal do Rio de Janeiro (NUCAT/PEQ/COPPE/UFRJ), RJ (Brazil). Laboratorio de Nanocompositos Polimericos

    2012-07-01

    Polyurethanes are important and versatile materials, mainly due to some of their properties, such as high resistance to abrasion and tearing, excellent absorption of mechanical shocks and good flexibility and elasticity. However, they have some drawbacks as well, such as low thermal stability and barrier properties. To overcome these disadvantages, various studies have been conducted involving organophilic polyurethane/montmorillonite nanocomposites. The investigation of the structure of polyurethane/clay nanocomposites has mainly been done by X-ray diffraction (XRD) and transmission electron microscopy (TEM). In this work, PU/clay nanocomposite films obtained by solution intercalation were studied. The nanocomposites were characterized by XRD and low-field nuclear magnetic resonance (LF-NMR). The LF-NMR measurements, with determination of the spin-lattice relaxation time of the hydrogen nucleus, supplied important information about the molecular dynamics of these nanocomposites. The X-ray diffraction measurements validated the results found by NMR. The thermal stability of the material was also determined by thermogravimetric analysis (TGA) under an inert atmosphere. A slight improvement in this stability was observed in the nanocomposite in comparison with polyurethane (author)

  5. NMR study of materials for immobilisation of nuclear waste; Etude par RMN de materiaux pour l'immobilisation de dechets nucleaires

    Energy Technology Data Exchange (ETDEWEB)

    Emery, J. [Universite du Maine, Lab. de Physique de l' Etat Condense, UMR 6087, 72 - Le Mans (France); Dacheux, N.; Clavier, N.; Genet, M.; Brandel, V. [Paris-11 Univ., Inst. de Physique Nucleaire, Groupe de Radiochimie, 91 - Orsay (France); Quarton, M. [Paris-6 Univ. Pierre et Marie Curie, Institut des Materiaux de Paris-Centre, CNRS-FR 2482, Lab. de Cristallochimie du Solide, 75 (France)

    2004-07-01

    We present an NMR investigation on thorium phosphate hydrogen phosphate (TPHP), which is a precursor for thorium phosphate diphosphate (TPD), that is one of the four retained matrix for the study of the actinide immobilisation. As XRD cannot work, it is particularly difficult to define the TPHP chemical formula: Th{sub 2}(PO{sub 4}){sub 2}HPO{sub 4}.H{sub 2}O or Th{sub 4}(PO{sub 4}){sub 4}P{sub 2}O{sub 7}.3 H{sub 2}O. In this contribution, we show that a local technique as NMR can bring an answer to this problem. (authors)

  6. The TMS34010 graphic processor - an architecture for image visualization in NMR tomography; O processador grafico TMS34010 - uma arquitetura para visualizacao de imagem em tomografia por RMN

    Energy Technology Data Exchange (ETDEWEB)

    Slaets, Jan Frans Willem; Paiva, Maria Stela Veludo de; Almeida, Lirio O.B

    1989-12-31

    This abstract presents a description of the minimum system implemented with the graphic processor TMS34010, which will be used in the reconstruction, treatment and interpretation f images obtained by NMR tomography. The project is being developed in the LIE (Electronic Instrumentation Laboratory), of the Sao Carlos Chemistry and Physical Institute, S P, Brazil and is already in operation 4 refs., 7 figs.

  7. Aplicación y nuevos desarrollos de la espectroscopía por RMN para el estudio de procesos de reconocimiento molecular entre carbohidratos y sus receptores

    OpenAIRE

    Berbís Moreno, Manuel Álvaro

    2014-01-01

    Los carbohidratos constituyen uno de los tipos de biomoléculas más complejos y ubicuos, cuyo reconocimiento por parte de receptores proteicos pertenecientes a diversas familias (lectinas, anticuerpos, enzimas y virus) determina una variedad de respuestas relacionadas con procesos fisiológicos y patológicos. El conocimiento, a nivel atómico, de la estructura de los carbohidratos y de sus interacciones con proteínas es esencial para una completa comprensión de muchos procesos vitales, así como ...

  8. Cânfora: um bom modelo para ilustrar técnicas de RMN Camphor: a good model for illustrating NMR techniques

    Directory of Open Access Journals (Sweden)

    Julliane Diniz Yoneda

    2007-01-01

    Full Text Available The use of Nuclear Magnetic Resonance spectroscopy to establish the three-dimensional structures of molecules is an important component of modern Chemistry courses. The combination of techniques that can be used for this purpose is conveniently illustrated by their application to the camphor molecule. This paper presents applications of several techniques used in NMR spectral interpretation in an increasing order of complexity. The result of individual experiments is illustrated in order to familiarize the user with the way connectivity through bonds and through space is established from 1D/2D-NMR spectra and molecular stereochemistry is determined from different NMR experiments.

  9. Análise do teor e da qualidade dos lipídeos presentes em sementes de oleaginosas por rmn de baixo campo

    Directory of Open Access Journals (Sweden)

    André F. Constantino

    2014-01-01

    Full Text Available To choose among the variety of oleaginous plants for biodiesel production, the oil content of several matrices was determined through different low-field ¹H nuclear magnetic resonance (NMR experiments with varied pulse sequences, namely single-pulse, spin-echo, CPMG, and CWFP. The experiments that involved the first three sequences showed high correlation with each other and with the solvent extraction method. The quality of the vegetable oils was also evaluated on the basis of the existing correlation between the T2 values of the oils and their properties, such as viscosity, iodine index, and cetane index. These analyses were performed using HCA and PCA chemometric tools. The results were sufficiently significant to allow separation of the oleaginous matrices according to their quality. Thus, the low-field ¹H NMR technique was confirmed as an important tool to aid in the selection of oleaginous matrices for biodiesel production.

  10. Solid NMR characterization of hydrogen solid storage matrices; Caracterisation par RMN du solide des matrices de stockage solide de l'hydrogene

    Energy Technology Data Exchange (ETDEWEB)

    Pilette, M.A.; Charpentier, T.; Berthault, P. [CEA Saclay, Dept. de Recherche sur l' Etat Condense, les Atomes et les Molecules, Lab. de Structure et Dynamique par Resonance Magnetique Lab. Claude Frejacques - CEA/CNRS URA 331, DSM/DRECAM/SCM, 91 - Gif sur Yvette (France)

    2007-07-01

    The aim of this work is to develop and validate characterization tools by NMR imagery and spectroscopy of the structure of materials for hydrogen storage, and of their evolution during load/unload cycles. The two main topics of this work are in one hand the analysis of the local structure of the materials and the understanding of their eventual modifications, and in another hand, the in-situ analysis of the distribution and diffusion of hydrogen inside the storage material. (O.M.)

  11. Magnetism and electronic structure for RMn{sub 2} (R=Y and lanthanoids) with the cubic Laves phase (C15) structure

    Energy Technology Data Exchange (ETDEWEB)

    Terao, Kiyosi E-mail: terk005@gipac.shinshu-u.ac.jp; Yamada, Hideji

    2004-05-01

    Ab initio calculations for the electronic structure are carried out by means of LMTO-ASA with and without the GGA correction. The observed antiferromagnetic state with complicated spin configuration has slightly higher energy than that with the layered spin configuration near the observed volume and slightly lower than that for larger volume. In ferromagnetic configuration, Mn moment shows complicated dependence on volume and magnetic field.

  12. Propiedades Físico-químicas por RMN de 1H y Constituyentes en el Aceite de Carapa guianensis por ESI-MS

    Directory of Open Access Journals (Sweden)

    Elson Farias Silva

    2015-01-01

    Full Text Available The Andiroba belongs to the botanical family Meliaceae, found in the Amazon mainly two varieties, Carapa guianensis and C. procera. They are species with large logging utility and extracted oil has many uses, especially in lighting, such as healing use, insecticide and anti-inflammatory. In this paper the physico-chemical properties of oil of C. guianensis in São João da Beacon, Roraima through calculations from 1H NMR spectrum using the computer program PROTÓLEOS properties are studied by ESI-MS technique to determine the constituents of said oil are linolenic acid (9.99%, linoleic acid (13.14%, oleic acid (47.32%, unsaturated (70.45% fatty acid and saturated fatty acids (29.55%. The extracted oil of andiroba oil has a yield of 67.03% being the physicochemical properties of the oil as follows: 48.4 mg I2 / g of iodine; 161.67 mg KOH / g of saponification; 1.84% of acid; 1004.02 g / mol average molecular weight; 159.83 mg KOH / g of ester value; 98.87% percent of ester and 0.9166 g / cm3 for the density at 25 ° C. Constituents determined by ESI-MS include: 1,1'-methyl-2,2'-dicarboxylate diantraquinona, dimethyl pirofosfatosantoninate, 2,4,6-tris- (3,5-di-butyl-4-tec -hidroxibencil styrene, (2,3,7,8,12,13,17,18-octanoilporfirinate -Mg (II.

  13. Study of crystalline morphology and phase structure in poly(styrene-b-ethylene oxide-b-styrene) triblock copolymers bu solid state RMN spin diffusion

    Energy Technology Data Exchange (ETDEWEB)

    Mantovani, Gerson L., E-mail: gerson.mantovani@ufabc.edu.b [Universidade Federal do ABC (UFABC), Santo Andre, SP (Brazil). Centro de Engenharia, Modelagem e Ciencias Sociais Aplicadas; Bonk, Fabio A. [Universidade Estadual de Campinas (IQ/UNICAMP) SP (Brazil). Inst. de Quimica; Caldarelli, Stefano Caldarelli [Aix-Marseille Universite ISm2, Site de Saint Jerome, Marseille (France); Phan, Trang; Bertin, Denis [Universite de Provence, Site de Saint Jerome, Marseille (France); Azevedo, Eduardo R. de; Bonagamba, Tito J. [Universidade de Sao Paulo (IF/USP), Sao Carlos, SP (Brazil). Inst. de Fisica

    2009-07-01

    The phase structure and crystalline morphology of a series of polystyrene-b-polyethylene oxide-b-polystyrene (PS-b- PEO-b-PS) triblock copolymers, with different compositions and molecular weights, has been studied by solid-state NMR. WAXS and DSC measurements were used to detect the presence of crystalline domains of polyethylene oxide (PEO) blocks at room temperature as a function of the copolymer composition. {sup 1}H NMR spin diffusion analyses provided an estimation of the size of the dispersed phases of the nano structured copolymers. (author)

  14. Determinación de las constantes de acidez del 2-(aminometil) bencimidazol por RMN de 13C, Espectrofotometría y potenciometría

    OpenAIRE

    Sierra Zenteno, Araceli

    2013-01-01

    En el presente trabajo se reporta la determinación de las constantes de equilibrio ácido-base del 2-(aminometil) bencimidazol en medio acuoso, refinadas mediante los programas computacionales HypNMR, SQUAD y SUPERQUAD a partir de información experimental obtenida por resonancia magnética nuclear de 13C, espectrofotometría UV/Vis y potenciometría respectivamente. Los pka’s obtenidos con las técnicas empleadas, son consistentes entre si y con la información publicada anteriormente. Así mismo se...

  15. NMR study of electrode materials for lithium ion-batteries; Etude par RMN de materiaux d'electrode pour batteries lithium-ion

    Energy Technology Data Exchange (ETDEWEB)

    Chazel, C.

    2006-01-15

    This work is devoted to the study of LiMO{sub 2} et LiM{sub 2}O{sub 4} (M: transition metal) intercalation compounds used as electrode material for lithium-ion batteries. Solid state NMR allows one to characterise the local environment of the lithium ions present in these phases by the use of the hyperfine interactions due to the presence of some electron spin density coming from localised electrons (Fermi-contact shift) or itinerant electrons (Knight shift) on the lithium nucleus. By following the transformation of the LiNiO{sub 2} layered phase into the LiNi{sub 2}O{sub 4} spinel material using lithium NMR, we studied the nature of the asymmetric signal observed for LiNiO{sub 2}, and the influence of the departure from the ideal stoichiometry; we showed a coupled ion/electron hopping in Li{sub X}NiO{sub 2} phases linked to Li/vacancy and Ni{sup 3+}/Ni{sup 4+} ordering, and finally showed the existence of structural defects within the LiNi{sub 2}O{sub 4} spinel phase obtained by thermal treatment of Li{sub 0.5}NiO{sub 2}. Lithium NMR of the intercalated materials obtained from the LiTi{sub 2}O{sub 4} and Li{sub 4}Ti{sub 5}O{sub 12} spinels showed a metallic behaviour for Li{sub 2}Ti{sub 2}O{sub 4} with a Knight shift of the NMR signal similar to that of LiTi{sub 2}O{sub 4}, and signals intermediate in nature between Knight and Fermi-contact shifts for Li{sub 7}Ti{sub 5}O{sub 12}. (author)

  16. Determination of collisional quenching rate coefficient of {{\\rm{N}}}_{2}({{\\rm{A}}}^{3}{{\\rm{\\Sigma }}}_{{\\rm{u}}}^{+}) by H2O

    Science.gov (United States)

    Suzuki, S.; Itoh, H.

    2017-06-01

    The measurement of the effective lifetime of {{{N}}}2({{{A}}}3{{{Σ }}}{{u}}+) in mixtures of nitrogen and small amounts of H2O (10.2 and 103 ppm) was carried out while observing the transient ionization current after turning off the ultraviolet (UV) light illuminating the cathode in a non-self-sustained Townsend discharge region. The transient current was formed by the emitted current sustained by the γ m action of metastable excited molecules {{{N}}}2({{{A}}}3{{{Σ }}}{{u}}+), which were produced by the impact of electrons with nitrogen molecules in the gap, and returned to the cathode by diffusion. Then, the collisional quenching rate coefficient of {{{N}}}2({{{A}}}3{{{Σ }}}{{u}}+) by H2O, the diffusion coefficient of {{{N}}}2({{{A}}}3{{{Σ }}}{{u}}+), and the reflection coefficient of {{{N}}}2({{{A}}}3{{{Σ }}}{{u}}+) at the cathode surface were determined from the observed effective lifetime of {{{N}}}2({{{A}}}3{{{Σ }}}{{u}}+) by an analytical procedure based on solving the diffusion equation. The obtained collisional quenching rate coefficient of {{{N}}}2({{{A}}}3{{{Σ }}}{{u}}+,{v}=0) by H2O was (5.7 ± 0.6) × 10-13 cm3 s-1.

  17. 12. Brazilian meeting on magnetic resonance; mini-course in NMR. Abstracts and program; 12. Jornada brasileira de ressonancia magnetica; mini-curso em RMN

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2012-07-01

    Theoretical and experimental papers are presented in these proceedings comprehending the following subjects: nuclear magnetic resonance, organic and non organic compounds, polymers, petroleum, physical chemistry, chemical structures, molecular biology, molecular structures and proteins.

  18. High - pressure synchrotron x-ray diffraction study of RMnO3 (R = Eu, Gd, Tb and Dy) upto 50 GPa

    Science.gov (United States)

    Muthu, D. V. S.; Midgley, A. E.; Scott, P. R.; Kruger, M. B.; Sahu, J. R.; Sood, A. K.; Rao, C. N. R.

    2012-07-01

    We have carried out synchrotron based high-pressure x-ray diffraction study of orthorhombic EuMnO3, GdMnO3, TbMnO3 and DyMnO3 up to 54.4, 41.6, 47.0 and 50.2 GPa, respectively. The diffraction peaks of all the four manganites shift monotonically to higher diffraction angles and the crystals retain the orthorhombic structure till the highest pressure. We have fitted the observed volume versus pressure data with the Birch-Murnaghan equation of state and determined the bulk modulus to be 185 ± 6 GPa, 190 ± 16 GPa, 188 ± 9 GPa and 192 ± 8 GPa for EuMnO3, GdMnO3, TbMnO3 and DyMnO3, respectively. The bulk modulus of EuMnO3 is comparable to other manganites, in contrast to theoretical predictions.

  19. Evaluation of thermoplastic starch/MMT nanocomposites by nuclear magnetic resonance (NMR); Avaliacao de nanocompositos de amido termoplastico e argila por RMN

    Energy Technology Data Exchange (ETDEWEB)

    Schlemmer, D.; Rodrigues, Tiago C.A.F.; Resck, I.S.; Sales, M.J.A., E-mail: danielas@unb.b [Universidade de Brasilia (LabPol/UnB), DF (Brazil). Inst. de Quimica. Lab. de Pesquisa em Polimeros

    2010-07-01

    Starch has been studied for replace petrochemical plastics for short shelf life. However, the starch films have limitations: sensitivity to moisture and poor mechanical strength. This can be improved by incorporating loads such as montmorillonite, forming nanocomposites. Nanocomposites were prepared with 1, 3, 5 and 10% of montmorillonite, using vegetable oils of Brazilian Cerrado as plasticizers. The NMR spectra of oils are similar, but the intensities of the signals varying with the proportion of fatty acids. The molar mass of the oils was also calculated by NMR. The spectrum of CP/MAS {sup 13}C NMR for starch presented a duplet in 97 and 98 ppm, on the amorphous domains of C-1, indicating a crystal type A. The spectra of the nanocomposites are similar to those of starch and oils. No new peaks appear, suggesting that there are no strong chemical bonds between components. (author)

  20. Time domain NMR study of Agar-gelatin blends; Estudo por RMN no dominio do tempo de blendas de Agar- gelatina

    Energy Technology Data Exchange (ETDEWEB)

    Mattos, Ritamara; Pericini, H.A.; Tambelli, Caio E., E-mail: tambelli@usp.br [Universidade de Sao Paulo (USP), Pirassununga, SP (Brazil). Faculdade de Zootecnia e Engenharia de Alimentos; Raphael, Ellen [Universidade Federal de Sao Joao del Rei (UFSJ), MG (Brazil). Departamento de Ciencias Naturais; Magon, Claudio J.; Donoso, P. [Universidade de Sao Paulo (USP), Sao Carlos, SP (Brazil). Instituto de Fisica

    2015-07-01

    This communication presents results of {sup 1}H time domain nuclear magnetic resonance of Agar-Gelatin blends plasticised with glycerol, cross-linked with formaldehyde and containing acetic acid. The spin-spin relaxation decay curves of samples obtained from CPMG experiments were inverted into corresponding distributions of relaxation times using NNLS (Non Negative Least Square) algorithm. The continuous distributions reveals up to four components of spin-spin relaxation times (T{sub 2}). The two components at short T{sub 2} were associated with protons in different environments of Agar and gelatin polymer chain. The two components at longer T{sub 2} can be associated with the glycerol that is the responsible to promote the proton conduction in the blend. (author)

  1. Time domain NMR and conductivity study of apple pectin biopolymers; Estudo por RMN no dominio do tempo e condutividade em filmes biopolimericos de pectina de maca

    Energy Technology Data Exchange (ETDEWEB)

    Mattos, Ritamara I.; Souto, Sergio; Tambelli, Caio E., E-mail: cristal_br@yahoo.com.br [Universidade de sao Paulo (USP), Pirassununga, SP (Brazil). Faculdade de Zootecnia e Engenharia de Alimentos

    2015-07-01

    This communication presents results of {sup 1}H nuclear magnetic resonance of continuous distributions of spin-spin relaxation time (T{sub 2}) and A.C. conductivity of apple pectin biopolymers plasticized with glycerol and containing acetic acid. The continuous distributions reveals up to three components of spin-spin relaxation times (T{sub 2}). The two short T{sub 2} components were associated with protons of pectin polymer chain and the longer T{sub 2} can be attributed with the protons of the glycerol. The conductivity values increase with glycerol concentration with maximum at 7.9 x 10{sup -4} S cm{sup -1} for sample with 3.0 g of glycerol at 83 deg C. The behavior of activation energy and T{sub 2} continuous distribution indicate an increase of proton mobility due the structural changes caused by glycerol addition. (author)

  2. Time domain NMR and conductivity study of apple pectin biopolymers; Estudo por RMN no dominio do tempo e condutividade em filmes biopolimericos de pectina de maca

    Energy Technology Data Exchange (ETDEWEB)

    Mattos, Ritamara; Souto, Sergio; Tambelli, Caio E., E-mail: cristal_br@yahoo.com.br [Universidade de Sao Paulo (USP), Pirassununga, SP (Brazil). Faculdade de Zootecnia e Engenharia de Alimentos

    2013-07-01

    This communication presents results of {sup 1}H nuclear magnetic resonance of continuous distributions of spin-spin relaxation time (T{sub 2}) and A.C. conductivity of apple pectin biopolymers plasticised with glycerol and containing acetic acid. The continuous distributions reveals up to three components of spin-spin relaxation times (T{sub 2}). The two short T{sub 2} components were associated with protons of pectin polymer chain and the longer T{sub 2} can be attributed with the protons of the glycerol. The conductivity values increase with glycerol concentration with maximum at 7.9 x 10{sup -4} S cm{sup -1} for sample with 3.0 g of glycerol at 83 deg C. The behavior of activation energy and T{sub 2} continuous distribution indicate an increase of proton mobility due the structural changes caused by glycerol addition. (author)

  3. Three-dimensional calculation of the electromagnetic fields produced by power transmission lines; Calculo tridimensional de los campos electromagneticos producidos por lineas electricas

    Energy Technology Data Exchange (ETDEWEB)

    Fernandez, Juan C.; Bisceglia, Mateo; Acosta, Eduardo O. [Universidad de Buenos Aires (Argentina). Facultad de Ingenieria. Lab. de Electrooptica]. E-mail: jcfernan@fi.uba.ar

    2001-07-01

    The used methods for calculation of produced electromagnetic fields by power transmission lines, assumes straight power transmission lines working in parallel to a plane soil. The influence of the associated curvature to its weight is depreciated, or it is introduced by means of a horizontal line of a intermediate height among the maximum and minimum heights of the power line. In this work it is compared the created values by horizontal and catenary lines. By means of investigations, it has been found a situation where for larger arrows there are great differences between the exact calculation and the approximation of horizontal line, and also the situation which shows that the better approximation is obtained by means of placing the horizontal line something above the minimum height.

  4. Calculations of the actinide transmutation with HELIOS for fuels of light water reactors; Calculos de la transmutacion de actinidos con HELIOS para combustibles de reactores de agua ligera

    Energy Technology Data Exchange (ETDEWEB)

    Francois L, J.L.; Guzman A, J.R. [UNAM-FI, Laboratorio de Analisis en Ingenieria de Reactores Nucleares, Paseo Cuauhnahuac 8532, Jiutepec, Morelos (Mexico)]. e-mail: jlfl@fi-b.unam.mx

    2006-07-01

    In this work a comparison of the obtained results with the HELIOS code is made and those obtained by other similar codes, used in the international community, respect to the transmutation of smaller actinides. For this the one it is analyzed the international benchmark: 'Calculations of Different Transmutation Concepts', of the Nuclear Energy Agency. In this benchmark two cell types are analyzed: one small corresponding to a PWR standard, and another big one corresponding to a PWR highly moderated. Its are considered two types of burnt of discharge: 33 GWd/tHM and 50 GWd/tHM. The following types of results are approached: the k{sub eff} like a function of the burnt one, the atomic densities of the main isotopes of the actinides, the radioactivities in the moment in that the reactor it is off and in the times of cooling from 7 up to 50000 years, the reactivity by holes and the Doppler reactivity. The results are compared with those obtained by the following institutions: FZK (Germany), JAERI (Japan), ITEP (Russia) and IPPE (Russian Federation). In the case of the eigenvalue, the obtained results with HELIOS showed a discrepancy around 3% {delta}k/k, which was also among other participants. For the isotopic concentrations: {sup 241}Pu, {sup 242} Pu and {sup 242m} Am the results of all the institutions present a discrepancy bigger every time, as the burnt one increases. Regarding the activities, the discrepancy of results is acceptable, except in the case of the {sup 241} Pu. In the case of the Doppler coefficients the discrepancy of results is acceptable, except for the cells with high moderation; in the case of the holes coefficients, the discrepancy of results increases in agreement with the holes fraction increases, being quite high to 95% of holes. In general, the results are consistent and in good agreement with those obtained by all the participants in the benchmark. The results are inside of the established limits by the work group on Plutonium Fuels and Innovative Fuel Cycles of the Nuclear Energy Agency. (Author)

  5. Theory and control calculations. Application to BWR and PWR; Teoria y calculo de elementos de control, Aplicacion a PWR y BWR

    Energy Technology Data Exchange (ETDEWEB)

    Velarde, G.; Guerra, J.

    1972-07-01

    A theoretical method to extend the applicability of P{sub 1} approximation to strong absorbers is given. Tables of effective diffusion parameters for slab and cylindrical geometry as well as a summary of expressions for obtaining the extrapolation length in cases of interest, are included. (Author) 21 refs.

  6. DIMCO. A new system for mechanical and bidimensional, of nuclear fuel pins; DIMCO un nuevo sistema de calculo mecanico de combustibles nucleares

    Energy Technology Data Exchange (ETDEWEB)

    Moreno, A.

    1977-07-01

    The system developed in JEN, for: the mechanical analysis uni and bidimensional, of nuclear fuels is presented. The mathematical and numerical foundations used, are here described. And so the models developed for effects such as swelling, cracking, clad growth etc. Numerical results for several cases are presented. a) Numerical test in one and two dimensions. b) Applicability range, c) Interaction effects. d) Influence of the power history. (Author) 17 refs.

  7. Validation of analytical method to calculate the concentration of conjugated monoclonal antibody; Validacao de metodo analitico para calculo de concentracao de anticorpo monoclonal conjugado

    Energy Technology Data Exchange (ETDEWEB)

    Alcarde, Lais F.; Massicano, Adriana V.F.; Oliveira, Ricardo S.; Araujo, Elaine B. de, E-mail: lais_alcarde@hotmail.com [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2013-07-01

    The objective of this study was to develop a quantitative analytical method using high performance liquid chromatography (HPLC) to determine the antibody concentration in conjunction with bifunctional chelator. Assays were performed using a high performance liquid chromatograph, and the following conditions were used: flow rate of 1 mL / min, 15 min run time, 0.2 M sodium phosphate buffer pH 7.0 as the mobile phase and column of molecular exclusion BioSep SEC S-3000 (300 x 7.8 mm, 5 μM - Phenomenex). The calibration curve was obtained with AcM diluted in 0.2 M sodium phosphate buffer pH 7.0 by serial dilution, yielding the concentrations: 400 μg/mL, 200 μg/mL, 100 μg/mL, 50 μg/mL, 25 μg/mL and 12.5 μg/mL. From the calibration curve calculated the equation of the line and with it the concentration of the immunoconjugate. To ensure the validity of the method accuracy and precision studies were conducted. The accuracy test consisted in the evaluation of 3 samples of known concentration, being this test performed with low concentrations (50 μg/mL), medium (100 μg/mL) and high (200 μg/mL). The precision test consisted of 3 consecutive measurements of one sample of known concentration, subject to the conditions set forth above for the other tests. The correlation coefficient of the standard curve was greater than 97%, the accuracy was satisfactory at low concentrations as well as accuracy. The method was validated by showing it for the accurate and precise determination of the concentration of the immunoconjugate. Furthermore, this assay was found to be extremely important, because using the correct mass of the protein, the radiochemical purity of the radioimmunoconjugate was above 95% in all studies.

  8. ORBITALES. A program for the calculation of wave functions with an analytical central potential; ORBITALES. Programa de calculo de Funciones de Onda para una Potencial Central Analitico

    Energy Technology Data Exchange (ETDEWEB)

    Yunta Carretero; Rodriguez Mayquez, E.

    1974-07-01

    In this paper is described the objective, basis, carrying out in FORTRAN language and use of the program ORBITALES. This program calculate atomic wave function in the case of ths analytical central potential (Author) 8 refs.

  9. Mathematical model for heat loss calculation through a window; Modelo para el calculo de la perdida de calor por una ventana

    Energy Technology Data Exchange (ETDEWEB)

    Fissore Sch, Adelqui; Cuevas B, Cristian [Universidad de Concepcion (Chile). Facultad de Ingenieria. Dept. de Ingenieria Mecanica]. E-mail: afissore@udec.cl; ccuevas@udec.cl

    2000-07-01

    In the present work a semi-empirical model for heat loss by convection at an indoor window surface with curtain or blind is given. With this model, the convection heat transfer coefficient and temperature of the air at confined space between the curtain and the glass can be calculated. The curtain was modeled with a paper due to the low thermal inertia that it has. The model is based on experimental data obtained for four separations between the paper and the window. Data from numerical simulation program are also used. (author)

  10. Criteria for calculation of effective dose from the individual monitoring; Criterios para calculo de dose efetiva a partir da monitoracao individual

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2005-11-15

    This Regulation refers to the requirements of the Regulation CNEN-NN.3.01. 'Basic Act of Radiological Protection', as expressed in the section 5.9, and its application to the effective dose calculation for individual occupationally exposed. from the internal and external individual monitoring data

  11. Calculation methods of reactivity using derivatives of nuclear power and Filter fir; Metodos para o calculo da reatividade usando derivadas da potencia nuclear e o filtro FIR

    Energy Technology Data Exchange (ETDEWEB)

    Diaz, Daniel Suescun

    2007-07-01

    This work presents two new methods for the solution of the inverse point kinetics equation. The first method is based on the integration by parts of the integral of the inverse point kinetics equation, which results in a power series in terms of the nuclear power in time dependence. Applying some conditions to the nuclear power, the reactivity is represented as first and second derivatives of this nuclear power. This new calculation method for reactivity has special characteristics, amongst which the possibility of using different sampling periods, and the possibility of restarting the calculation, after its interruption associated it with a possible equipment malfunction, allowing the calculation of reactivity in a non-continuous way. Apart from this reactivity can be obtained with or without dependency on the nuclear power memory. The second method is based on the Laplace transform of the point kinetics equations, resulting in an expression equivalent to the inverse kinetics equation as a function of the power history. The reactivity can be written in terms of the summation of convolution with response to impulse, characteristic of a linear system. For its digital form the Z-transform is used, which is the discrete version of the Laplace transform. In this method it can be pointed out that the linear part is equivalent to a filter named Finite Impulse Response (Fir). The Fir filter will always be, stable and non-varying in time, and, apart from this, it can be implemented in the non-recursive way. This type of implementation does not require feedback, allowing the calculation of reactivity in a continuous way. The proposed methods were validated using signals with random noise and showing the relationship between the reactivity difference and the degree of the random noise. (author)

  12. Calculation methodology of the thermal margin in the CAREM 25 reactor; Metodologia de calculo del margen termico en el reactor CAREM 25

    Energy Technology Data Exchange (ETDEWEB)

    Mazufri, Claudio M. [Investigacion Aplicada SE (INVAP), San Carlos de Bariloche (Argentina)

    1995-12-31

    According to the nuclear reactors characteristics, can be found different methodologies to appraise the thermal margin available in the core. In the particular case of the CAREM (25 MWe) reactor, where the core is cooled by low mass flux and there are zones with positive steam quality, such evaluation is critical. Due to these characteristics, it was necessary to develop one proper methodology. In the present work, the different steps of that development are described: the election of figures of merit for measure the thermal margin, the hypothesis to use, the election of the critical heat flux prediction model, model qualification and the specification of the core wide procedure. In each step assume criteria are discussed. (author). 9 refs, 1 tab, 1 fig.

  13. Adjusting of the power-factor correction. Technical, economic and financial implications; Calculo de correccion del factor de potencia. Implicaciones tecnicas, economicas y financieras

    Energy Technology Data Exchange (ETDEWEB)

    Eficiencia Energetica aplicada (Energiza) [Ciudad Juarez, Chihuahua (Mexico)

    2005-07-01

    A power-factor is a device formed by a dielectric set and electrodes within a container with terminals, able to contribute with capacitance to an electrical circuit, such as: transformers, induction motors, regulators, air conditioning, welding machines, induction furnaces and ballasts. This document also tells us about the location of capacitors in their system, the electrical conductor, the monthly consumption electricity bill, of the benefits when adjusting the power-factor, the liberation of power of the transformer, the reduction of current in feeders, the reduction of losses in feeders, the diminution of the tension fall and the approximate average sale price. [Spanish] Un factor de potencia es un dispositivo formado por un conjunto de dielectrico y electrodos dentro de un recipiente con terminales, capaz de aportar capacitancia a un circuito electrico, como lo son: transformadores, motores de induccion, reguladores, aire acondicionado, maquinas soldadoras, hornos de induccion y balastros. Este documento tambien nos habla acerca de la localizacion de capacitores en su sistema, del conductor electrico, del recibo de consumo mensual de energia, de los beneficios al corregir factor de potencia, la liberacion de potencia del transformador, la reduccion de corriente en alimentadores, la reduccion de perdidas en alimentadores, la disminucion de la caida de tension y el precio de venta promedio aproximado.

  14. Calculation of modification to the toroidal magnetic field of the Tokamak Novillo. Part II; Calculo de modificacion al campo magnetico toroidal del Tokamak nivillo. Parte II

    Energy Technology Data Exchange (ETDEWEB)

    Melendez L, L.; Chavez A, E.; Colunga S, S.; Valencia A, R.; Lopez C, R.; Gaytan G, E

    1992-03-15

    In a cylindrical magnetic topology. the confined plasma experiences 'classic' collisional transport phenomena. When bending the cylinder with the purpose of forming a toro, the magnetic field that before was uniform now it has a radial gradient which produces an unbalance in the magnetic pressure that is exercised on the plasma in the transverse section of the toro. This gives place to transport phenomena call 'neo-classicist'. In this work the structure of the toroidal magnetic field produced by toroidal coils of triangular form, to which are added even of coils of compensation with form of half moon is analyzed. With this type of coils it is looked for to minimize the radial gradient of the toroidal magnetic field. The values and characteristics of B (magnetic field) in perpendicular planes to the toro in different angular positions in the toroidal direction, looking for to cover all the cases of importance are exhibited. (Author)

  15. El papel de sistemas de calculo formal en la comprensión de las matemáticas: el caso de la integral definida

    Directory of Open Access Journals (Sweden)

    Vicente D. Estruch

    2010-06-01

    Full Text Available Este estudio forma parte de una investigación más amplia que pretende estudiar la incidencia de la tecnología de la información y de la comunicación (Tic en la comprensión de nociones básicas del cálculo. En concreto, en este artículo mostraremos una serie de actividades diseñadas con un asistente matemático (MatlabQc y bajo el marco teórico constructivista Acción-Proceso-Objeto y eSquema (Apos, que pretenden mejorar la comprensión de la integral definida en alumnos de ingenierías relacionadas con el medio ambiente y la naturaleza. Estas prácticas se diseñaron pensando en estudiantes con un conocimiento básico del programa; no obstante pueden plantarse actividades que requieran un mayor conocimiento del asistente.

  16. Paradigm shift in LUNG SBRT dose calculation associated with Heterogeneity correction; Cambio de paradigma en SBRT pulmonar asociada al calculo de dosis con correccion de heterogeneidad

    Energy Technology Data Exchange (ETDEWEB)

    Zucca Aparicio, D.; Perez Moreno, J. M.; Fernandez Leton, P.; Garcia Ruiz-Zorrilla, J.; Pinto Monedero, M.; Marti Asensjo, J.; Alonso Iracheta, L.

    2015-07-01

    Treatment of lung injury SBRT requires great dosimetric accuracy, the increasing clinical importance of dose calculation heterogeneities introducing algorithms that adequately model the transport of particles narrow beams in media of low density, as with Monte Carlo calculation. (Author)

  17. Calculation of the magnetic vector potential in the TJ-II; Calculo del Potencial Magnetico Vector en el TJ-II

    Energy Technology Data Exchange (ETDEWEB)

    Lopez Fraguas, A.; Lopez Bruna, D.; Romero, J. A.

    2005-07-01

    The properties of the vector magnetic potential and its usefulness to calculate magnetic fluxes in both stationary and time-dependent conditions are p revised in this report. We have adapted to the TJ-II Flexible Heliac efficient numerical expressions to calculate the vector potential, calculating in addition the magnetic flux with this formalism in circumstances whose complexity makes very convenient the use of the vector potential. The result on induced voltages offer theoretical support to the measurements of induced voltage due to the OH coils in the plasma, like the measurements provided by the loop voltage diagnostic installed in the TJ-II, as well as to the cylindrical approximation of the plasma often used to interpret experimental data. (Author) 11 refs.

  18. GIS (Geographic Information Systems) based calculation on hydrocarbon generated volume: Amazon Basin example; O uso de SIG no calculo de hidrocarbonetos gerados: exemplo da Bacia do Amazonas

    Energy Technology Data Exchange (ETDEWEB)

    Pedrinha, Saulo; Simoes, Leonardo; Goncalves, Felix T.T.; Carneiro, Jason T.G. [Petroleum Geoscience Technology Ltda. (PGT), Rio de Janeiro, RJ (Brazil)

    2008-07-01

    The calculation of the volume of hydrocarbons generated from a particular source rock a sedimentary basin provides numerical data that help to better describe the petroleum system, and evaluate its potential. Among the various methodologies developed for calculating the volume of oil there is a proposal by Schmoker (1994), which has the advantage to take into account the occurrence of the source rock area in the basin, and the spatial variations in the main geological parameters. Using the tools of a GIS, through the manipulation of georeferred maps, it is possible to calculate the volume of oil generated in a way that would be virtually impossible by using punctual data, only. Even the discretiation maps in minors areas allows, via attribute table in the GIS, the application of a Monte Carlo simulation, which allows to incorporate all the uncertainties related to the input data in the calculation, obtaining distributions of volumes associated with various parts of the final map being integrated throughout the basin. Isopac and maturation maps (Gonzaga et al., 2000), along with TOC data from Barreirinha formation, Amazon Basin, have been scanned and georeferred and, once in the GIS database, were treated in order to spatially distribute the geological properties of the source rock. Then, such maps were handled in accordance with Schmoker (1994) method, leading to a map of mass and distribution of oil generated in the basin at the regional scale. (author)

  19. SYSMOD: user-interface for data processing, calculation codes and analysis of PWR lattices; SYSMOD: una interfase-usuario para el procesamiento, calculo y analysis de redes PWR

    Energy Technology Data Exchange (ETDEWEB)

    Gonzalez, Alejandro; Milian, Daniel [Instituto Superior de Ciencias y Tecnologias Nucleares (ISCTN), La Habana (Cuba). E-mail: agg@ctn.isctn.edu.cu

    2000-07-01

    The task of the physical calculation of the reactor demand of the management of a great volume of information and inclose the stages for processing of data, calculations and analysis of their results. These stages are highly sensible to human mistakes, that's why is imprescindible that them undergo automatization, doing tracked all the process against mistake or unexpected result. The user-interface SYSMOD was developed over the platform IDE Delphi 3.0, visual language driven to events. It to consist in of the principal menu, which inclose between its options the preparation of the input data (File and Edit) to the pre-processors for the calculation codes of reactors. The output information may be showed in graphic and/or alphanumeric format (Data-Process). SYSMOD endures two applications for the management of the data base for the data during the preparation of the input for the pre-processors of the spectral calculation, so as for the organization, conservation and presentation for the obtained results. The carried out of the lattices and global codes, takes place from this application, over the platform MS-DOS (Run). SYSMOD regards the possibility for the debugging of the codes (Debugging), so as the benchmarks qualified to so effect (Benchmark). SYSMOD has been applied for the analysis of te WWER-440 of the first unity of Juragua Nuclear Power Plant. (author)

  20. Renewability emergy index calculation in the evaluation of the sustainability of a national economy; Calculo do indice de renovabillidade emergetica na avaliacao da sustentabilidade de uma economia nacional

    Energy Technology Data Exchange (ETDEWEB)

    Siche Jara, Raul Benito [Universidad Nacional de Trujillo, La Libertad (Peru). Fac. de Ciencias Agropecuarias. Escuela de Ingenieria Agroindustrial], e-mail: Siche.J.R@gmail.com; Ortega Rodriguez, Enrique [Universidade Estadual de Campinas (DEA/FEA/UNICAMP), SP (Brazil). Lab. de Engenharia Ecologica e Informatica Aplicada], e-mail: ortega@fea.unicamp.br

    2006-07-01

    In this study, the emergy methodology was used to analyze the sustainability of the Peruvian economic system. The resources (natural and not natural) and importations had been accounting in units of solar emergy using data of the Peruvian economy for the year 2004. Emergy is an energy measure based in the contribution of the resources and its influence, defined as the energy of a type required producing a flow or storage of another type. The focus of this study is the calculation of the emergy index call 'renewability' (REN), considered as a general measure of the ecological sustainability. In a long period, only systems or processes with high REN are sustainable. This index is calculated by the accounting of the resources renewed used in the economy in emergy units (2.17E+23 seJ) and divided by emergy total that enters to the economic system (6.93E+23 seJ), resulting a REN of 0.31. The renewable resources that use Peru almost represent 20% of the total of renewable resources available in the system. The great amount of renewable resources that Peru can potentially use was calculated in 11.44E+23 seJ, meaning that the system can be more sustainable if the economy is based on increasing the use of renewable resources and to diminish the use of non-renewable resources and imported resources. These data show that Peru has a relatively sustainable economy that can improve or get worse, depending of its politics in the use of resources. (author)

  1. Development of a computer code for shielding calculation in X-ray facilities; Desenvolvimento de um codigo computacional para calculos de blindagem em salas radiograficas

    Energy Technology Data Exchange (ETDEWEB)

    Borges, Diogo da S.; Lava, Deise D.; Affonso, Renato R.W.; Moreira, Maria de L.; Guimaraes, Antonio C.F., E-mail: diogosb@outlook.com, E-mail: deise_dy@hotmail.com, E-mail: raoniwa@yahoo.com.br, E-mail: malu@ien.gov.br, E-mail: tony@ien.gov.br [Instituto de Engenharia Nuclear (IEN/CNEN-RJ), Rio de Janeiro, RJ (Brazil)

    2014-07-01

    The construction of an effective barrier against the interaction of ionizing radiation present in X-ray rooms requires consideration of many variables. The methodology used for specifying the thickness of primary and secondary shielding of an traditional X-ray room considers the following factors: factor of use, occupational factor, distance between the source and the wall, workload, Kerma in the air and distance between the patient and the receptor. With these data it was possible the development of a computer program in order to identify and use variables in functions obtained through graphics regressions offered by NCRP Report-147 (Structural Shielding Design for Medical X-Ray Imaging Facilities) for the calculation of shielding of the room walls as well as the wall of the darkroom and adjacent areas. With the built methodology, a program validation is done through comparing results with a base case provided by that report. The thickness of the obtained values comprise various materials such as steel, wood and concrete. After validation is made an application in a real case of radiographic room. His visual construction is done with the help of software used in modeling of indoor and outdoor. The construction of barriers for calculating program resulted in a user-friendly tool for planning radiographic rooms to comply with the limits established by CNEN-NN-3:01 published in September / 2011.

  2. Development of a computational code for calculations of shielding in dental facilities; Desenvolvimento de um codigo computacional para calculos de blindagem em instalacoes odontologicas

    Energy Technology Data Exchange (ETDEWEB)

    Lava, Deise D.; Borges, Diogo da S.; Affonso, Renato R.W.; Guimaraes, Antonio C.F.; Moreira, Maria de L., E-mail: deise_dy@hotmail.com, E-mail: diogosb@outlook.com, E-mail: raoniwa@yahoo.com.br, E-mail: tony@ien.gov.br, E-mail: malu@ien.gov.br [Instituto de Engenharia Nuclear (IEN/CNEN-RJ), Rio de Janeiro, RJ (Brazil)

    2014-07-01

    This paper is prepared in order to address calculations of shielding to minimize the interaction of patients with ionizing radiation and / or personnel. The work includes the use of protection report Radiation in Dental Medicine (NCRP-145 or Radiation Protection in Dentistry), which establishes calculations and standards to be adopted to ensure safety to those who may be exposed to ionizing radiation in dental facilities, according to the dose limits established by CNEN-NN-3.1 standard published in September / 2011. The methodology comprises the use of computer language for processing data provided by that report, and a commercial application used for creating residential projects and decoration. The FORTRAN language was adopted as a method for application to a real case. The result is a programming capable of returning data related to the thickness of material, such as steel, lead, wood, glass, plaster, acrylic, acrylic and leaded glass, which can be used for effective shielding against single or continuous pulse beams. Several variables are used to calculate the thickness of the shield, as: number of films used in the week, film load, use factor, occupational factor, distance between the wall and the source, transmission factor, workload, area definition, beam intensity, intraoral and panoramic exam. Before the application of the methodology is made a validation of results with examples provided by NCRP-145. The calculations redone from the examples provide answers consistent with the report.

  3. Activation calculation of steel of the control rods of TRIGA Mark III reactor; Calculo de activacion del acero de las barras de control del reactor TRIGA Mark III

    Energy Technology Data Exchange (ETDEWEB)

    Garcia M, T.; Cruz G, H. S.; Ruiz C, M. A.; Angeles C, A., E-mail: teodoro.garcia@inin.gob.mx [ININ, Carretera Mexico-Toluca sn, 52750 Ocoyoacac, Estado de Mexico (Mexico)

    2014-10-15

    In the pool of TRIGA Mark III reactor of the Instituto Nacional de Investigaciones Nucleares (ININ), there are control rods that were removed from the core, and which are currently on shelves of decay. These rods were part of the reactor core when only had fuel standard (from 1968-1989). To conduct a proper activation analysis of the rods, is very important to have well-characterized the materials which are built, elemental composition of the same ones, the atomic densities and weight fractions of the elements that constitute them. To determine the neutron activation of the control rods MCNP5 code was used, this code allows us to have well characterized the radionuclides inventory that were formed during irradiation of the control rods. This work is limited to determining the activation of the steel that is part of the shielding of the control rods, the nuclear fuel that is in the fuel follower does not include. The calculation model of the code will be validated with experimental measurements and calculating the activity of fission products of the fuel follower which will take place at the end of 2014. (Author)

  4. SHIELD 1.0: development of a shielding calculator program in diagnostic radiology; SHIELD 1.0: desenvolvimento de um programa de calculo de blindagem em radiodiagnostico

    Energy Technology Data Exchange (ETDEWEB)

    Santos, Romulo R.; Real, Jessica V.; Luz, Renata M. da [Hospital Sao Lucas (PUCRS), Porto Alegre, RS (Brazil); Friedrich, Barbara Q.; Silva, Ana Maria Marques da, E-mail: ana.marques@pucrs.br [Pontificia Universidade Catolica do Rio Grande do Sul (PUCRS), Porto Alegre, RS (Brazil)

    2013-08-15

    In shielding calculation of radiological facilities, several parameters are required, such as occupancy, use factor, number of patients, source-barrier distance, area type (controlled and uncontrolled), radiation (primary or secondary) and material used in the barrier. The shielding design optimization requires a review of several options about the physical facility design and, mainly, the achievement of the best cost-benefit relationship for the shielding material. To facilitate the development of this kind of design, a program to calculate the shielding in diagnostic radiology was implemented, based on data and limits established by National Council on Radiation Protection and Measurements (NCRP) 147 and SVS-MS 453/98. The program was developed in C⌗ language, and presents a graphical interface for user data input and reporting capabilities. The module initially implemented, called SHIELD 1.0, refers to calculating barriers for conventional X-ray rooms. The program validation was performed by the comparison with the results of examples of shielding calculations presented in NCRP 147.

  5. Aspects of the transmissibility calculation for corner point grids; Aspectos sobre o calculo de transmissibilidades em malhas formadas por contatos parciais

    Energy Technology Data Exchange (ETDEWEB)

    Cemin Junior, Angelo; Maliska, Clovis R.; Cordazzo, Jonas [Santa Catarina Univ., Florianopolis, SC (Brazil). Dept. de Engenharia Mecanica. Lab. de Simulacao Numerica em Mecanica dos Fluidos e Transferencia de Calor (SINMEC)]. E-mail: cemin@sinmec.ufsc.br, maliska@sinmec.ufsc.br; jonas@sinmec.ufsc.br

    2003-07-01

    The present work analyzes important aspects in the transmissibility calculation used by most commercial software in petroleum reservoir simulation. Initially, the transmissibility calculation formula, according to the literature is presented. Using this definition, it is described the transmissibility calculation for corner point grids, the most general case. Following, the present work analyzes how the commercial software, especially IMEX (IMplicit EXplicit Black Oil Simulator, of CMG), performs the transmissibility determination in non-matching grids. Based on those calculations, it is demonstrated that most commercial software do not use expressions which gives the exact transmissibility, even for refined grids. (author)

  6. Calculi and comparison of efficiency of solar thermal collector for some applications; Calculo y comparacion de rendimientos de captadores solares termicos para distintas aplicaciones

    Energy Technology Data Exchange (ETDEWEB)

    Lopez-Rodriguez, F.; Segador, C.; Marcos, C.; Cuadros, F.

    2004-07-01

    This paper deals with simple procedure, applicable in any part of the world where climatic variables can be estimated, comparing the efficiency of solar collector for designing of specific installations for domestic hot water and general heating. The values of the climatic variables; average daily solar radiation, the max. and min. average monthly temperatures and average monthly hours of sunshine went obtained from the Climwat FAO database. The process, although not taking into account the dynamic evolution of the variables, and using approximate values, is accurate and overall is manageable for its simplicity, comparing rapid the efficiency of the collectors and size the installations. (Author)

  7. Calculation of shielding of X rays in radiotherapy facilities with computer aid; Calculo de blindagem para instalacoes de radioterapia por raios X com auxilio de computador

    Energy Technology Data Exchange (ETDEWEB)

    Pedrosa, Paulo Sergio; Farias, Marcos Santana [Instituto de Engenharia Nuclear (IEN), Rio de Janeiro, RJ (Brazil)]. E-mail: pedrosa@ien.gov.br; msantana@ien.gov.br; Gavazza, Sergio [Instituto Militar de Engenharia (IME), Rio de Janeiro, RJ (Brazil). Dept. das Ciencias Fundamentais, Radiacao e Meio Ambiente]. E-mail: gavazza@ugf.br

    2005-07-01

    This work presents a methodology for calculation of shielding of X rays in radiotherapy facilities with computer aid. A friendly program, called RadTeraX, was developed in programming language Delphi that, through manual data input of a basic project of architecture and of some parameters, interprets the geometry and calculates the shielding of the walls, ground and roof of a radiotherapy installation for X rays. As a final product, this program supplies a graphic screen in the computer with all the input data and the calculation of the shielding, besides the respective calculation memory. Still today, in Brazil, the calculation of the shielding for radiotherapy facilities with X rays has been made based on recommendations of NCRP-49, that establishes a necessary calculation methodology to the elaboration of a shielding project. However, in high energies, where it is necessary the construction of a maze, NCRP-49 is insufficient, so that in this field, studies were made originating an article that proposes a solution for the problem and this solution was implemented in the program. The program can be applied in the practical execution of shielding projects for radiotherapy facilities and in didactic way in comparison with NCRP-49 and has been registered under number 00059420 at INPI - Instituto Nacional da Propriedade Industrial (National Institute of Industrial Property). (author)

  8. Considerations on the calculation of volumes in two planning systems; Consideraciones sobre el calculo de volumenes en dos sistemas de planificacion

    Energy Technology Data Exchange (ETDEWEB)

    Gomez-Tenedor Alonso, S.; Rincon Perez, M.; Penedo Cobos, J. M.; Garcia Castejon, M. A.

    2011-07-01

    The discrepancies in the calculation of the same volume between different planning systems impact on dose-volume histograms and therefore clinical assessment of dosimetry for patients. The transfer, by a local network, tomographic study (CT) and contours of critical organs of patients, between our two planning systems allows us to evaluate the calculation of identical volumes.

  9. Calculation engine of the planning system for radiotherapy with microbeams; Motor de calculo del sistema de planificacion para la radioterapia con microhaces

    Energy Technology Data Exchange (ETDEWEB)

    Martinez-Rovira, I.; Sempau, J.; Bravin, A.; Prezado, Y.

    2011-07-01

    The TPS calculation engine includes a full modeling of the synchrotron source (energy spectrum, phase space and polarization of the incident photons) and transport through 42 m of optical elements to position the patient, where generating a phase space file (PSF) with the state of the particles. This PSF is used as input for the calculation of doses in a model of the patient, based on computed axial tomography (CT).

  10. Operating Cell Temperature Determination in Flat-Plate Photovoltaic Modules; Calculo de la Temperature de Operacion de Celulas Solares en un Panel Fotovoltaico Plano

    Energy Technology Data Exchange (ETDEWEB)

    Chenlo, F.

    2002-07-01

    Two procedures (simplified and complete) to determine the operating cell temperature in photovoltaic modules operating in real conditions assuming isothermal stationary modules are presented in this work. Some examples are included that show the dependence of this temperature on several environment (sky, ground and ambient temperatures, solar irradiance, wind speed, etc.) and structural (module geometry and size, encapsulating materials, antirreflexive optical coatings, etc) factors and also on electrical module performance. In a further step temperature profiles for non-isothermal modules are analysed besides transitory effects due to variable irradiance and wind gusts. (Author)

  11. User's and Programmer's Guide for HPC Platforms in CIEMAT; Guia de Utilizacion y programacion de las Plataformas de Calculo del CIEMAT

    Energy Technology Data Exchange (ETDEWEB)

    Munoz Roldan, A.

    2003-07-01

    This Technical Report presents a description of the High Performance Computing platforms available to researchers in CIEMAT and dedicated mainly to scientific computing. It targets to users and programmers and tries to help in the processes of developing new code and porting code across platforms. A brief review is also presented about historical evolution in the field of HPC, ie, the programming paradigms and underlying architectures. (Author) 32 refs.

  12. Counting efficiency for radionuclides decaying by beta and gamma-ray emission; Calculo de la eficiencia de recuento de nucleidos que experimentan desintegracion beta y desexcitacion gamma simple

    Energy Technology Data Exchange (ETDEWEB)

    Grau, A.; Garcia-Torano, E.

    1988-07-01

    In this paper, counting efficiency vs figure of merit for beta and gamma-ray emitters has been computed. It is assumed that the decay scheme has only a gamma level and the beta-ray emission may be coincident with the gamma-rays or the internal-conversion electrons. The radionuclides tabulated are: 20 {sub 0}, 20{sub p}, 28{sub A}l, 35{sub p}, 41{sub A}r, 42{sub K}, 47{sub S}e, 62{sub F}e, 66{sub C}u, 81{sub G}e, 86{sub B}b, 108{sub R}u, 112{sub p}d, 121{sub S}n(Ni), 122{sub I}n, 129{sub I}, 141{sub C}e 171{sub T}m, 194{sub O}s, 2O3{sub H}g, 205{sub H}g, 210{sub p}b, 225{sub R}a, 142{sub p}r, 151{sub S}m, 244{sub A}m(m). It has been assumed that the liquid is a toluene based scintillator solution in standard glass vials containing 10 cm''3. (Author) 8 refs.

  13. Preliminary shielding calculation for the system of CyberKnife robotic radiosurgery; Calculo de blindagem preliminar para o sistema de radiocirurgia robotica CyberKnife

    Energy Technology Data Exchange (ETDEWEB)

    Toreti, Dalila; Xavier, Clarice; Moura, Fabio, E-mail: clarice.xavier@rem.ind.b, E-mail: fabio.moura@rem.ind.b [REM Industria e Comercio Ltda., Sao Paulo, SP (Brazil)

    2011-10-26

    The CyberKnife robotic system uses a manipulator with six grade of freedom for positioning a 6 MV Linac accelerator for treatment of lesions. This paper presents calculations for a standard room, with 200 cm of thickness walls primary, build for a CyberKnife system, and calculations for a room originally designed for a Linac conventional (with gantry), with secondary barriers of 107 cm thickness. After the realization of shielding for both rooms, the results shown that walls of standard room with 200 cm thickness are adequate for the secondary shield, and for a room with a conventional Linac, from all six evaluated points, two would require additional shielding of nine cm and four cm of concrete with 2.4 g/cubic cm. This shows that the CyberKnife system can be installed in a originally designed room for a conventional Linac with neither restrict nor any shielding, since no incidence of beams on the secondary barriers is existent

  14. Calculation about a modification to the toroidal magnetic field of the Tokamak Novillo. Part I; Calculo sobre una modificacion al campo magnetico toroidal del Tokamak Novillo. Parte I

    Energy Technology Data Exchange (ETDEWEB)

    Chavez A, E.; Melendez L, L.; Colunga S, S.; Valencia A, R.; Lopez C, R.; Gaytan G, E

    1991-07-15

    The charged particles that constitute the plasma in the tokamaks are located in magnetic fields that determine its behavior. The poloidal magnetic field of the plasma current and the toroidal magnetic field of the tokamak possess relatively big gradients, which produce drifts on these particles. These drifts are largely the cause of the continuous lost of particles and of energy of the confinement region. In this work the results of numerical calculations of a modification to the 'traditional' toroidal magnetic field that one waits it diminishes the drifts by gradient and improve the confinement properties of the tokamaks. (Author)

  15. Analyse of the international recommendations on the calculation of absorbed dose in the biota; Analise das recomendacoes internacionais sobre calculo de dose absorvida na biota

    Energy Technology Data Exchange (ETDEWEB)

    Pereira, Wagner de S.; Py Junior, Delcy de A., E-mail: wspereira@inb.gov.b, E-mail: delcy@inb.gov.b [Industrias Nucleares do Brasil (UTM/INB), Pocos de Caldas, MG (Brazil). Unidade de Tratamento de Minerios; Universidade Federal Fluminense (LARARA/UFF), Niteroi, RJ (Brazil). Lab. de Radiobiologia e Radiometria; Kelecom, Alphonse [Universidade Federal Fluminense (UFF), Niteroi, RJ (Brazil). Programa de Pos-Graduacao em Ciencia Ambiental

    2011-10-26

    This paper evaluates the recommendations of ICRP which has as objective the environmental radioprotection. It was analysed the recommendations 26, 60, 91, 103 and 108 of the ICRP. The ICRP-103 defined the concept of animal and plant of reference (APR) to be used in the RAP based on the calculation of absorbed dose based on APR concept. This last view allows to build a legal framework of environmental protection with a etic, moral and scientific visualization, more defensible than the anthropomorphic concept

  16. Approximate calculus of the auto transformers and power transformers capacitances; Calculo aproximado de las capacitancias de autotransformadores y transformadores de potencia

    Energy Technology Data Exchange (ETDEWEB)

    Carrasco, Gustavo [C.V.G. Electrificacion del Caroni, C.A. (EDELCA), Caracas (Venezuela)]. E-mail: gcarrasco@edelca.com.ve

    2001-07-01

    This paper develops a mathematical relation for the approximated calculus of the capacitances of the EDELCA power transformers and auto transformers. This mathematical relation is based on the type of transformers construction (Nucleus and shell type), the dielectric properties of the internal insulation material and the electric parameters (Voltage and power)

  17. Parameter calculation tool for the application of radiological dose projection codes; Herramienta de calculo de parametros para la aplicacion de codigos de proyeccion de dosis radiologicas

    Energy Technology Data Exchange (ETDEWEB)

    Galindo G, I. F.; Vergara del C, J. A.; Galvan A, S. J. [Instituto Nacional de Electricidad y Energias Limpias, Reforma 113, Col. Palmira, 62490 Cuernavaca, Morelos (Mexico); Tijerina S, F., E-mail: francisco.tijerina@cfe.gob.mx [CFE, Central Nucleoelectrica Laguna Verde, Carretera Federal Cardel-Nautla Km 42.5, 91476 Municipio Alto Lucero, Veracruz (Mexico)

    2016-09-15

    The use of specialized codes to estimate the radiation dose projection to an emergency postulated event at a nuclear power plant requires that certain plant data be available according to the event being simulated. The calculation of the possible radiological release is the critical activity to carry out the emergency actions. However, not all of the plant data required are obtained directly from the plant but need to be calculated. In this paper we present a computational tool that calculates the plant data required to use the radiological dose estimation codes. The tool provides the required information when there is a gas emergency venting event in the primary containment atmosphere, whether well or dry well and also calculates the time in which the spent fuel pool would be discovered in the event of a leak of water on some of the walls or floor of the pool. The tool developed has mathematical models for the processes involved such as: compressible flow in pipes considering area change and for constant area, taking into account the effects of friction and for the case of the spent fuel pool hydraulic models to calculate the time in which a container is emptied. The models implemented in the tool are validated with data from the literature for simulated cases. The results with the tool are very similar to those of reference. This tool will also be very supportive so that in postulated emergency cases can use the radiological dose estimation codes to adequately and efficiently determine the actions to be taken in a way that affects as little as possible. (Author)

  18. Development of computer programme for the use of empirical calculation of mining subsidence; Desarrollo informatico para utilizacion de los metodos empiricos de calculo de subsidencia minera

    Energy Technology Data Exchange (ETDEWEB)

    1999-09-01

    The fundamental objective of the project is the elaboration of a user friendly computer programme which allows to mining technicians an easy application of the empirical calculation methods of mining subsidence. As is well known these methods use, together with a suitable theoretical support, the experimental data obtained during a long period of mining activities in areas of different geological and geomechanical nature. Thus they can incorporate to the calculus the local parameters that hardly could be taken into account by using pure theoretical methods. In general, as basic calculation method, it has been followed the procedure development by the VNIMI Institute of Leningrad, a particularly suitable method for application to the most various conditions that may occur in the mining of flat or steep seams. The computer programme has been worked out on the basis of MicroStation System (5.0 version) of INTERGRAPH which allows the development of new applications related to the basic aims of the project. An important feature, of the programme that may be quoted is the easy adaptation to local conditions by adjustment of the geomechanical or mining parameters according to the values obtained from the own working experience. (Author)

  19. Code Betal to calculation Alpha/Beta activities in environmental samples; Programa de ordenador Betal para el calculo de la actividad Beta/Alfa de muestras ambientales

    Energy Technology Data Exchange (ETDEWEB)

    Romero, L.; Travesi, A.

    1983-07-01

    A codes, BETAL, was developed, written in FORTRAN IV, to automatize calculations and presentations of the result of the total alpha-beta activities measurements in environmental samples. This code performs the necessary calculations for transformation the activities measured in total counts, to pCi/1., bearing in mind the efficiency of the detector used and the other necessary parameters. Further more, it appraise the standard deviation of the result, and calculus the Lower limit of detection for each measurement. This code is written in iterative way by screen-operator dialogue, and asking the necessary data to perform the calculation of the activity in each case by a screen label. The code could be executed through any screen and keyboard terminal, (whose computer accepts Fortran IV) with a printer connected to the said computer. (Author) 5 refs.

  20. Modelo para calculo estimación del carbono en Tipo Forestal Roble-Raulí-Coigüe en la Reserva Nacional Malleco: Chile

    OpenAIRE

    Norman Moreno Garcia; Miguel Angel Herrera Machuca; Rinaldo Luiz Caraciolo Ferreira

    2011-01-01

    El objetivo de este trabajo es la selección de un modelo para estimación de carbono en Tipo Forestal Roble-Raulí y Coigüe. La recolección de datos se realizo en la Reserva Nacional Malleco. Cada sitio fue representado por un grupo de 5 parcelas (cuadradas, de lado 35m, superficie 1225m2), ubicadas en un transecto según la pendiente más fuerte. Fueron estimados los volúmenes de madera con y sin corteza de la totalidad de los individuos por medio de funciones para cada especie del tipo forestal...

  1. Calculation of electromagnetic field in electric machines through the finite element: Electromagnetic modeling; Calculo de campos electromagneticos en maquinas electricas mediante elemento finito: Modelacion electromagnetica

    Energy Technology Data Exchange (ETDEWEB)

    Rosales, Mario F. [Instituto de Investigaciones Electricas, Cuernavaca (Mexico)

    1987-12-31

    In this article are presented the general characteristics of the electromagnetic phenomena that can be described by means of the software CALIIE-2D of the Instituto de Investigaciones Electricas (IIE) derived from a modeling based in the magnetic and electric potentials, always using the MKS rationalized units system. Closed regions are considered with axial or moving symmetry to incorporate the bi-dimensional behavior of the electromagnetic fields. The possibility of means with movement is also included. [Espanol] En este articulo se presentan las caracteristicas generales de los fenomenos electromagneticos que pueden describirse mediante el programa de computo CALIIE-2D, del Instituto de Investigaciones Electricas (IIE), que provienen de una modelacion basada en los potenciales magnetico y electrico, en esta se utiliza sistema MKS racionalizado de unidades. Se consideran regiones cerradas con simetria axial o traslacional para incorporar el comportamiento bidimensional de los campos electromagneticos, se incluye tambien la posibilidad de medios con movimiento.

  2. Calculate the high solar radiation for photovoltaic panels in Chile; Aproximacio al calculo de la oferta de energia por paneles fotovoltaicos en Chile

    Energy Technology Data Exchange (ETDEWEB)

    Cancino, Beatriz; Roth, Pedro; Stolz, German [Universidad Tecnica Federico Santa Maria, Valparaiso (Chile); Bonneschky, Alexis [Cottbus University, Cottbus (Germany)

    2000-07-01

    The aim of this work was to develop a method which permits to calculate and predict the theoretically possible electrical energy which can be obtained in different places in Chile with photovoltaic panels used in solar home systems. Chile is a country with a high solar radiation, specially in its northern part, between parallels 18 degrees with a daily mean energy of 4600 Wh/m{sup 2} over the year and 37 degrees, with 3700 Wh/m{sup 2}. Therefore, the use of photovoltaic power is an interesting alternative to be studied and used. Nevertheless, the photovoltaic possibilities have not been studied and no evaluation of real possibilities exist. In a previous paper, the absence of an installation guide for solar home systems have been mentioned. And also the lack of information regarding the real electrical energy needs of people. This work pretends to be the first approximation to a detailed chart and list of possible electric supplies using photovoltaic panels in different locations of Chile. It is made with a computer program which permits to calculate the solar radiation on a tilted surface, on a hourly bases. It uses geographical data and the daily average of monthly radiation. Therefore, the hourly energy, harnessed by the panel can be established and the total energy for some place calculated. [Spanish] El objetivo de este trabajo, es el de mostrar a traves de un listado y un mapa nacional, la cantidad teorica de energia electrica que puede ser obtenida a traves del uso de paneles fotovoltaicos principalmente destinados a Solar Home System (SHS) en Chile. Chile es un pais con una alta oferta de energia solar ubicada principalmente en la zona norte y centro del pais, aproximadamente entre los paralelos 18 grados (sobre 4600 Wh/m{sup 2} dia promedio anual) y 37 grados Sur (sobre 3700 Wh/m{sup 2} dia promedio anual). Por lo que el uso de paneles fotovoltaicos representa una alternativa interesante de ser estudiada y aprovechada. Sin embargo, no existe una evaluacion del potencial solar fotovoltaico en Chile. En un trabajo previo, se detecto la falta de una guia obligatoria y general para la instalacion de los SHS, ademas de la falta de informacion en relacion al potencial electrico real para lograr satisfacer el consumo de las personas. Este trabajo pretende ser la primera aproximacion a una carta detallada de la oferta electrica para el uso de paneles fotovoltaicos en Chile. El mapa de oferta electrica se realiza con la ayuda de un programa computacional el que contiene las ecuaciones necesarias a fin de obtener la radiacion solar para superficie inclinada hora a hora a partir de los datos geograficos y de radiacion solar global promedio mensual sobre superficie horizontal del lugar. Ademas el programa contiene las ecuaciones de un panel fotovoltaico con las que es posible obtener la energia en un lapso de una hora, utilizando como dato de entrada la radiacion a traves de un dia tipico de cada mes y la curva de oferta de energia electrica o curva de energia electrica proporcionada por el panel fotovoltaico escogido.

  3. La aplicacion del Sistema Europeo de Transferencia y Acumulacion de Creditos. Consideraciones sobre la nocion de carga de trabajo y los procedimientos de calculo

    National Research Council Canada - National Science Library

    Menendez Varela, Jose Luis

    2009-01-01

    .... Sin embargo, el consenso sobre el sistema y lo avanzado del proceso no excluyen la existencia de dificultades, incertidumbres e incluso riesgos que atanen principalmente a su aplicacion practica...

  4. Calculation of oil bubble point pressure: fit sensitivity studies; Calculo da pressao de bolha de oleos: estudo de sensibilidade no seu ajuste

    Energy Technology Data Exchange (ETDEWEB)

    Rocha, P.S. [PETROBRAS, Salvador, BA (Brazil). Unidade de Negocios da Bahia]. E-mail: psrocha@petrobras.com.br; Alves, D.C.R.; Fontes, C.H.O.; Costa, G.M.N. [Universidade Salvador (UNIFACS), Salvador, BA (Brazil). Centro de Estudos em Petroleo e Gas Natural (CEPGN)]. E-mail: gloria.costa@unifacs.br

    2003-07-01

    Equations of state (EOS) are widely used in phase equilibrium calculations of hydrocarbon mixtures. The matching of the bubble point pressure is often used for the description of the mixture's properties. To study the sensitivity of the matching, a database, containing 50 experimental measurements of bubble point pressures, was built from several references. >From the data, we have obtained a new correlation to estimate the bubble point pressure of an oil. This correlation, unlike the usual ones, uses as independent variables the oil composition. For the calculation of the bubble point pressures we have used Soave's EOS and the SPECS simulator. The objective of this study was to develop a heuristic (rules) of the sensitivity of the adequacy between the calculated and measured bubble point pressure, related to the EOS's parameters. For each oil, the parameters of the EOS are correlated to the bubble point pressure. We selected the linear fit (usually preferred) and performed a statistical analysis relating the fitted angular and linear coefficients with the oil characteristics. This procedure allows us to consider any other kind of oil outside our database. (author)

  5. Comparative studies of empirical correlations for calculation of minimum miscibility pressure; Estudo comparativo de correlacoes empiricas para o calculo da pressao minima de miscibilidade

    Energy Technology Data Exchange (ETDEWEB)

    Rocha, P.S. [PETROBRAS, Salvador, BA (Brazil). Unidade de Negocios da Bahia]. E-mail: psrocha@petrobras.com.br; Meirelles, C.P.; Santos, R.B.; Costa, G.M.N. [Universidade Salvador (UNIFACS), Salvador, BA (Brazil). Centro de Estudos em Petroleo e Gas Natural (CEPGN)]. E-mail: gloria.costa@unifacs.br

    2003-07-01

    The miscible recovery of oil can be obtained by displacing it using CO{sub 2} at a pressure greater than a minimum level, called minimum miscibility pressure. In this study we used three correlations for the calculation of the minimum miscibility pressure in multiple contact: Yellig and Metcalfe method; Alston, Kokolis and James method; and Enick, Holden and Morsi method. For a carefully evaluation of the range of application and restrictions, a data base from the literature containing 125 combinations of oils, temperatures and solvents, for which the minimum miscibility pressures were available using pure or impure CO{sub 2} from experiments in slim tube apparatus. This study revealed that the best method is the Alston, Kokolis and James one, although the average relative error and the standard deviation are greater than the values cited by the authors. An evaluation of the correlation coefficient revealed that the number of independent variables in each method is insufficient. Although the second and third methods consider the impurities in the CO{sub 2}, the error obtained in the calculation of the minimum miscibility pressure using pure CO{sub 2} is lower than the one for impure CO{sub 2}, showing that the effects of the contaminants are not well described by the correlations as the authors say. (author)

  6. Algorithm approach for wear calculation of friction pairs of metallic materials; Enfoque algoritmico para el calculo del desgaste en pares de friccion de materiales metalicos

    Energy Technology Data Exchange (ETDEWEB)

    Martinez Perez, F.

    2000-07-01

    Tribological properties of since materials for friction pairs are nowadays part of the technological requirements they have a decisive influence on the useful life of these pairs. An essential parameter to be measured is the wear undergone by materials that is caused during their performance. These measures can be taken in both lab or field testing, but they can be also calculated. For this, the wear mechanism must be taken into account. In the present paper, an algorithm for the calculation of wear based on the main disperse recommendations from the specialized literature is given. (Author) 16 refs.

  7. Developing a verification tool for calculations dissemination through COBAYA; Desarrollo de una herramienta de verificacion para calculos de difusion mediante COBAYA

    Energy Technology Data Exchange (ETDEWEB)

    Sabater Alcaraz, A.; Rucabado Rucabado, G.; Cuervo Gomez, D.; Garcia Herranz, N.

    2014-07-01

    The development of a software tool that automates the comparison of results with previous versions of the code and results using models of accuracy is crucial for implementing the code new functionalities. The work presented here has been the generation the mentioned tool and the set of reference cases that have set up the afore mentioned matrix. (Author)

  8. Multi-user software of radio therapeutical calculation using a computational network; Software multiusuario de calculo radioterapeutico usando una red de computo

    Energy Technology Data Exchange (ETDEWEB)

    Allaucca P, J.J.; Picon C, C.; Zaharia B, M. [Departamento de Radioterapia, Instituto de Enfermedades Neoplasicas, Av. Angamos Este 2520, Lima 34 (Peru)

    1998-12-31

    It has been designed a hardware and software system for a radiotherapy Department. It runs under an Operative system platform Novell Network sharing the existing resources and of the server, it is centralized, multi-user and of greater safety. It resolves a variety of problems and calculation necessities, patient steps and administration, it is very fast and versatile, it contains a set of menus and options which may be selected with mouse, direction arrows or abbreviated keys. (Author)

  9. An approximated method of calculation of neutron spectra in reactor cells; Um metodo aproximado de calculo do espectro de neutrons em celulas de reatores

    Energy Technology Data Exchange (ETDEWEB)

    Caldeira, Alexandre D. [Centro Tecnico Aeroespacial (CTA-IEAv), Sao Jose dos Campos, SP (Brazil). Inst. de Estudos Avancados

    2000-07-01

    This work deals with the cell neutron spectra calculated with the transport equation for an infinite medium applied to the homogenized cell. Considering a radioisotope production reactor fuel cell, as a sample case, the maximum deviation found between the approximated and the S{sub N} methods was 13%. (author)

  10. Measurements of neutron streaming energy spectra in shielding ducts; Medidas e calculos de espectro de energia de neutrons emergentes de um duto em uma blindagem

    Energy Technology Data Exchange (ETDEWEB)

    Angioletto, Elcio; Abe, Alfredo Y. [Centro Tecnologico da Marinha em Sao Paulo (CTMSP), SP (Brazil). E-mail: angiolet@net.ipen.br; Coelho, Rogerio P. [Instituto de Pesquisas Energeticas e Nucleares (IPEN), Sao Paulo, SP (Brazil)

    2000-07-01

    This work presents the measurements of neutron streaming, for different energy ranges, in shielding ducts. The shielding is composed of plates of different materials (borate polyethylene and paraffin). The two ducts are conceived as labyrinths in order to (a three-legged duct) minimize the radiation streaming. A 37 GBq Americium-Beryllium neutron source type was used for the experimental measurements. The fast neutron energy spectra were measured using a detection system with a liquid organic scintillator, NE-213 detector, and appropriate electronic equipment. The results are in good agreement with the literature. The measurements of thermal neutrons intensity were performed with a BF{sub 3} counter. The MCNP-4B code was used to simulate the experiment. The simulation was performed with success, obtaining a small discrepancy (9.0%) between the calculated results and the measurements with the BF{sub 3} counter, at the duct third leg. From the results it was possible to observe the thermal neutron streaming through the duct, the effects of neutron flux moderation, the attenuation in the shielding and also the neutron energy spectra modifications emerging from the shielding. (author)

  11. MCNP - transport calculations in ducts using multigroup albedo coefficients; Calculos de transporte em dutos utilizando coeficientes de albedo multigrupo no codigo MCNP

    Energy Technology Data Exchange (ETDEWEB)

    Ono, Shizuca; Vieira, Wilson J.; Garcia, Roberto D.M. [Centro Tecnico Aeroespacial (CTA-IEAv), Sao Jose dos Campos, SP (Brazil). Inst. de Estudos Avancados

    2000-07-01

    In this work, the use of multigroup albedo coefficients in Monte Carlo calculations of particle reflection and transmission by ducts is investigated. The procedure consists in modifying the MCNP code so that an albedo matrix computed previously by deterministic methods or Monte Carlo is introduced into the program to describe particle reflection by a surface. This way it becomes possible to avoid the need of considering particle transport in the duct wall explicitly, changing the problem to a problem of transport in the duct interior only and reducing significantly the difficulty of the real problem. The probability of particle reflection at the duct wall is given, for each group, as the sum of the albedo coefficients over the final groups. The calculation is started by sampling a source particle and simulating its reflection on the duct wall by sampling a group for the emerging particle. The particle weight is then reduced by the reflection probability. Next, a new direction and trajectory for the particle is selected. Numerical results obtained for the model are compared with results from a discrete ordinates code and results from Monte Carlo simulations that take particle transport in the wall into account. (author)

  12. Syrio. A program for the calculation of the inverse of a matrix; Syrio. Programa para el calculo de la inversa de una matriz

    Energy Technology Data Exchange (ETDEWEB)

    Garcia de Viedma Alonso, L.

    1963-07-01

    SYRIO is a code for the inversion of a non-singular square matrix whose order is not higher than 40 for the UNIVAC-UCT (SS-90). The treatment stands from the inversion formula of sherman and Morrison, and following the Herbert S. Wilf's method for special matrices, generalize the procedure to any kind of non-singular square matrices. the limitation of the matrix order is not inherent of the program itself but imposed by the storage capacity of the computer for which it was coded. (Author)

  13. A new model for induced voltage calculations in power transmission lines; Novo modelo para calculo de tensao induzida em LT's

    Energy Technology Data Exchange (ETDEWEB)

    Silveira, Fernando Henrique; Schroeder, Marco Aurelio de O.; Visacro Filho, Silverio; Soares Junior, Amilton [Minas Gerais Univ., Belo Horizonte, MG (Brazil). Lightning Research Center - Nucleo de Desenvolvimento Cientifico e Tecnologico em Descargas Atmosfericas]. E-mail: lrc@cpdee.ufmg.br

    2001-07-01

    In this document the authors present the previous results of accomplished simulations through a brand new model to calculate the induced voltage by atmospheric discharges on power transmission lines. Through geometric data variation from the transmission line and discharge parameters, it is executed a sensibility analysis concerning to the relevant factors in order to define the levels of induced voltage in the transmission line. Finally, the work aims to evaluate this phenomenon importance in connection with 138 kv transmission lines.

  14. Orintsol. Surfaces with assorted inclination: software to calculate the solar radiation; Orientsol. Superficies con distinta inclinacion Software para el calculo de la radiacion solar

    Energy Technology Data Exchange (ETDEWEB)

    Rus, C.; Almonacid, F.; Hontoria, L.; Perez, P. J.; Munoz, F. J.

    2009-07-01

    The Universidad de Jaen, conscious of the importance of using energy sources respectful with the environment, offers in its Technical Industry Engineer degree, in the specialties of: Mechanics, Electricity and Industrial electronics the optional subjects Solar electricity and Photovoltaic Facilities. With these matters is intended that the students acquire the capability of design, calculate, analyze their different applications. A fundamental aspect in solar facilities is how to know the incident radiation in the plant which we want to analyze or the size. Orintsol software tool, with a didactic aim, facilitates so teaching as learning about solar radiation received on inclined surfaces. (Author) 8 refs.

  15. Monte Carlo applied to calculation of shields of facilities used in industrial radiography; Monte Carlo aplicado al calculo de blindajes de instalaciones usadas en radiografia industrial

    Energy Technology Data Exchange (ETDEWEB)

    Martinez Ovalle, S. A.; Olaya Davila, H.; Reyes Caballero, F.

    2013-07-01

    The main objective of this work is to verify through Monte Carlo, the dimensions most appropriate in the shielding of an installation designed for Industrial radiography with a Co-60 Irradiator. (Author)

  16. Incertidumbre en los valores de la fuerza de oscilador de las lineas espectrales y su influencia en el calculo de abundancias

    Science.gov (United States)

    Marchiano, P. E.; Di Rocco, H. O.; Cruzado, A.

    In this paper; we compare oscillator strengths values from XeII lines theoretically obtained with values obtained via experimentation. We put forward a working hypothesis aimed at reaching the best possible agreement; and applying it to the study of abundances of other elements in the atmospheres of chemically peculiar stars. FULL TEXT IN SPANISH

  17. Calculation of electromagnetic fields in electric machines by means of the finite element. Computational aspects; Calculo de campos electromagneticos en maquinas electricas mediante elemento finito. Aspectos computacionales

    Energy Technology Data Exchange (ETDEWEB)

    Rosales, Mario; De la Torre, Octavio [Instituto de Investigaciones Electricas, Cuernavaca (Mexico)

    1989-12-31

    In this article are described the computational characteristics of the Package CALIIE 2D of the Instituto de Investigaciones Electricas (IIE), for the calculation of bi-dimensional electromagnetic fields. The computational implementation of the package is based in the electromagnetic and numerical statements formerly published in this series. [Espanol] En este articulo se describen las caracteristicas computacionales del paquete CALIIE 2D del Instituto de Investigaciones Electricas (IIE), para calcular campos electromagneticos bidimensionales. La implantacion computacional del paquete se basa en los planteamientos electromagneticos y numericos antes publicados en esta serie.

  18. Comparison between calculation methods of dose rates in gynecologic brachytherapy; Comparacion entre metodos de calculo de tasa de dosis en braquiterapia ginecologica8

    Energy Technology Data Exchange (ETDEWEB)

    Vianello, E.A.; Biaggio, M.F.; Dr, M.F.; Almeida, C.E. de [Laboratorio de Ciencias Radiologicas- (L.C.R.)-D.B.B.- UERJ- R. Sao Francisco Xavier, 524- Pav. HLC- sala 136- CEP 20550-013 Rio de Janeiro (Brazil)

    1998-12-31

    In treatments with radiations for gynecologic tumors is necessary to evaluate the quality of the results obtained by different calculation methods for the dose rates on the points of clinical interest (A, rectal, vesicle). The present work compares the results obtained by two methods. The Manual Calibration Method (MCM) tri dimensional (Vianello E., et.al. 1998), using orthogonal radiographs for each patient in treatment, and the Theraplan/T P-11 planning system (Thratonics International Limited 1990) this last one verified experimentally (Vianello et.al. 1996). The results show that MCM can be used in the physical-clinical practice with a percentile difference comparable at the computerized programs. (Author)

  19. Personal dosimetry calculations by means of radio pharmacokinetic and gamma graphic studies; Calculos de dosimetria personalizada por medio de estudios radiofarmacocineticos y gammagraficos

    Energy Technology Data Exchange (ETDEWEB)

    Arteaga de Murphy, C.; Ferro F, G.; Pedraza L, M.; Montoya M, C.E. [Departamento de Medicina Nuclear, Instituto Nacional de Ciencias Medicas y Nutricion, Vasco de Quiroga 15, 14000 Mexico D.F. (Mexico)

    2000-07-01

    The determination of the absorbed radiation dose is an essential factor to assess the risk to patient with a diagnostic study of nuclear medicine but over all it is indispensable for predicting the efficiency of individualized radio pharmacotherapy and weighting up the risk/benefit of the treatment. In studies for diagnostic or/and treatment of nuclear medicine generally the absorbed radiation dose is not determined for each patient since the methods for estimating it are laborious and include complex models such biological as mathematical, therefore is very important to have a relatively easy method. The obtained data with {sup 99m} Tc-Abp., a new radiopharmaceutical for osseous gammagraphy, were used with the purpose of exemplifying a practical method. The radio pharmacokinetic parameters were determined during 24 hours in 10 health voluntaries and serial gamma grams were taken during two hours to another voluntaries. The obtained data were used to estimate, with the MIRDOSE3 computer program, the absorbed radiation dose in an osseous dragging with {sup 99m} Tc-Abp. is low: 0.00472 m Gy/MBq to osseous marrow, mainly to the vertebral column and femur, and 0.00169 m Gy/ MBq to whole body. These data are lower than those informed in the medical literature for other bis phosphonates. (Author)

  20. Calculation of dose equivalents in organs due to photoneutrons from clinical accelerators; Calculo de dose equivalente em orgaos devido a fotoneutrons provenientes de aceleradores clinicos

    Energy Technology Data Exchange (ETDEWEB)

    Castro, Robson C. de; Silva, Ademir X. da; Crispim, Verginia R. [Universidade Federal, Rio de Janeiro, RJ (Brazil). Coordenacao dos Programas de Pos-graduacao de Engenharia. Programa de Engenharia Nuclear]. E-mail: rcastro@con.ufrj.br; Facure, Alessandro; Falcao, Rossana C. [Comissao Nacional de Energia Nuclear (CNEN), Rio de Janeiro, RJ (Brazil)]. E-mail: afsoares@cnen.gov.br; Lima, Marco A.F. [Universidade Federal Fluminense (UFF), Niteroi, RJ (Brazil). Dept. de Biologia Geral. Lab. de Radiobiologia e Radiometria]. E-mail: egbakel@vm.uff.br

    2005-07-01

    Radiotherapy with photon and electron beams still represents the most technique to control and treat tumour diseases. To increase the treatment efficiency of this technique is linked to the increase of beam energy, resulting in fast neutrons in the radiotherapic beams that contribute with an undesired dose to the patient. In this work has been calculated, using the MCNP4B computer code radiation of transport and an mathematical anthropomorphic phantom, the equivalent doses in organs originated from generated photoneutrons from heads of linear accelerators of medical use, that operates in the 15 MV, 18 MV, 20 MV and 25 MV. The calculated values for the equivalent doses in organs established by the 74 publication of ICRP has show variations between 0.11 mSv.n Gy{sup -1} and 7.03 mSv.n Gy{sup -1}, for the accelerator that uses 18 MV therapic beams, showing good agreement with existing values in the literature. (author)

  1. Calculating the movement speed of a contaminated material in soil; Calculo de la velocidad de movimiento de un material contaminado en suelo

    Energy Technology Data Exchange (ETDEWEB)

    Lopez G, D.

    2014-07-01

    The present work describes the project which consisted in the development of an application to facilitate and display a graphic where the displacement and behavior of radioactive contaminants in soil could be observed. Once the data are introduced to the system, this makes the necessary calculations to display a graphic where the displacement of the substance is displayed in a given time. Through the graphs resulting from the program, we can quickly see the behavior and movement of a contaminant substance, but by numerical simulation, it can determine the possible impact caused by a supposition spills of a radioactive substance in soil and thus able to take the appropriate measures to control or avoid an impact resulting highly harmful to health and the environment, so as to determine the distance and time in which the substance already change or transform into another. (Author)

  2. Calculo y comparacion de la prima de un reaseguro de salud usando el modelo de opciones de Black-Scholes y el modelo actuarial

    Directory of Open Access Journals (Sweden)

    Luis Eduardo Giron

    2015-12-01

    Full Text Available La presente investigación pretende calcular y comparar la prima de un reaseguro  usando el modelo de opciones de Black-Scholes y el modelo clásico actuarial tradicional. El período de análisis va desde enero de 2011 hasta diciembre de 2012. Los resultados obtenidos muestran que el modelo de Black-Scholes, que se utiliza normalmente para valorar opciones financieras, puede ser también usado para la estimación de primas de reaseguros de salud; y que la prima neta estimada a partir de este modelo se aproxima a las establecidas por el método actuarial, excepto cuando el deducible del reaseguro es muy alto (por encima de $200.000.000.

  3. Calculating seismic of slabs ITA NNP Garona; Calculo sismico de las losas del ATI de C.N. Santa maria de Garona

    Energy Technology Data Exchange (ETDEWEB)

    Ezeberry, J. I.; Guerrero, A.; Gamarra, J.; Beltran, F.

    2014-07-01

    This article describes the methodology that Idom has employed to perform the seismic evaluation of slabs within the ITA project of the NPP Santa Maria de Garona. Seismic calculations that have been conducted include consideration of the effects of the interaction of soil structure as well as the possible take-off containers with respect to slab during the earthquake. Therefore, the main contribution of the work is the study of the coupling of rolling containers with the flexibility of the whole ground-slab For calculations has been used ABAQUS/Explicit program, allowing to solve effectively the nonlinearities listed above using explicit integration algorithms over time. The results of the calculations reflect the importance of jointly analyse the seismic responses of slab and containers. (Author)

  4. Calculation of neutron fluence to dose equivalent conversion coefficients using GEANT4; Calculo de coeficientes de fluencia de neutrons para equivalente de dose individual utilizando o GEANT4

    Energy Technology Data Exchange (ETDEWEB)

    Ribeiro, Rosane M.; Santos, Denison de S.; Queiroz Filho, Pedro P. de; Mauricio, CLaudia L.P.; Silva, Livia K. da; Pessanha, Paula R., E-mail: rosanemribeiro@oi.com.br [Instituto de Radioprotecao e Dosimetria (IRD/CNEN-RJ), Rio de Janeiro, RJ (Brazil)

    2014-07-01

    Fluence to dose equivalent conversion coefficients provide the basis for the calculation of area and personal monitors. Recently, the ICRP has started a revision of these coefficients, including new Monte Carlo codes for benchmarking. So far, little information is available about neutron transport below 10 MeV in tissue-equivalent (TE) material performed with Monte Carlo GEANT4 code. The objective of this work is to calculate neutron fluence to personal dose equivalent conversion coefficients, H{sub p} (10)/Φ, with GEANT4 code. The incidence of monoenergetic neutrons was simulated as an expanded and aligned field, with energies ranging between thermal neutrons to 10 MeV on the ICRU slab of dimension 30 x 30 x 15 cm{sup 3}, composed of 76.2% of oxygen, 10.1% of hydrogen, 11.1% of carbon and 2.6% of nitrogen. For all incident energy, a cylindrical sensitive volume is placed at a depth of 10 mm, in the largest surface of the slab (30 x 30 cm{sup 2}). Physic process are included for neutrons, photons and charged particles, and calculations are made for neutrons and secondary particles which reach the sensitive volume. Results obtained are thus compared with values published in ICRP 74. Neutron fluence in the sensitive volume was calculated for benchmarking. The Monte Carlo GEANT4 code was found to be appropriate to calculate neutron doses at energies below 10 MeV correctly. (author)

  5. The role of advanced calculation and simulation tools in the evolution of fuel; El papel de las herramientas avanzadas de calculo y simulacion en la evolucion del combustible

    Energy Technology Data Exchange (ETDEWEB)

    Munoz-Reja, C.; Cerracin, A.; Corpa, R.

    2015-07-01

    This article is focused on the role of the advanced calculation/simulation tools on the development of the fuel designs as well as in the assessment of the effect of the changes in the operation. With this purpose, the article describes and shows some examples of the use by ENUSA of some of these tools in the fuel engineering. To conclude, the future on the evolution of the advanced tools is also presented. (Author)

  6. Modelo para calculo estimación del carbono en Tipo Forestal Roble-Raulí-Coigüe en la Reserva Nacional Malleco: Chile

    Directory of Open Access Journals (Sweden)

    Norman Moreno Garcia

    2011-12-01

    Full Text Available El objetivo de este trabajo es la selección de un modelo para estimación de carbono en Tipo Forestal Roble-Raulí y Coigüe. La recolección de datos se realizo en la Reserva Nacional Malleco. Cada sitio fue representado por un grupo de 5 parcelas (cuadradas, de lado 35m, superficie 1225m2, ubicadas en un transecto según la pendiente más fuerte. Fueron estimados los volúmenes de madera con y sin corteza de la totalidad de los individuos por medio de funciones para cada especie del tipo forestal en estudio. La cantidad de carbono almacenado a nivel de fuste de las parcelas fue estimada aplicando la función universal de carbono. En cada parcela se contabilizaron los árboles por clase diamétrico de DAP, siendo definidas las clases a partir del DAP mínimo de 3 cm y con una amplitud de 5 cm. Fueron ajustados los modelos de Spurr, Meyer, Stoate, Naslund y Schumacher-Hall. El modelo Schumacher-Hall presento el mejor ajuste de acuerdo a los indicadores estadísticos considerados, además de una mejor distribución de residuales.

  7. Independent dose calculation of the Tps Iplan in radiotherapy conformed with MLC; Calculo independiente de dosis del TPS Iplan en radioterapia conformada con MLC

    Energy Technology Data Exchange (ETDEWEB)

    Adrada, A.; Tello, Z.; Medina, L.; Garrigo, E.; Venencia, D., E-mail: jorge.alberto.adrada@gmail.com [Instituto Privado de Radioterapia, Obispo Oro 423, X5000BFI Cordoba (Argentina)

    2014-08-15

    The systems utilization of independent dose calculation in three dimensional-Conformal Radiation Therapy (3D-Crt) treatments allows a direct verification of the treatments times. The utilization of these systems allows diminishing the probability of errors occurrence generated by the treatment planning system (Tps), allowing a detailed analysis of the dose to delivering and review of the normalization point (Np) or prescription. The independent dose calculation is realized across the knowledge of dosimetric parameters of the treatment machine and particular characteristics of every individual field. The aim of this work is develops a calculation system of punctual doses for isocentric fields conformed with multi-leaf collimation systems (MLC), where the dose calculation is in conformity with the suggested ones by ICRU Report No. 42, 1987. Calculation software was realized in C ++ under a free platform of programming (Code::Blocks). The system uses files in format Rtp, exported from the Tps to systems of record and verification (Lantis). This file contains detailed information of the dose, Um, position of the MLC sheets and collimators for every field of treatment. The size of equivalent field is obtained from the positions of every sheet; the effective depth of calculation can be introduced from the dosimetric report of the Tps or automatically from the DFS of the field. The 3D coordinates of the isocenter and the Np for the treatment plan must be introduced manually. From this information the system looks the dosimetric parameters and calculates the Um. The calculations were realized in two accelerators a NOVALIS Tx (Varian) with 120 sheets of high definition (hd-MLC) and a PRIMUS Optifocus (Siemens) with 82 sheets. 705 patients were analyzed for a total of 1082, in plans made for both equipment s, the average uncertainty with regard to the calculation of the Tps is-0.43% ± 2.42% in a range between [-7.90 %, 7.50 %]. The major uncertainty was in Np near of the MLC. The software checks the dose in any Np, helps to detect mistakes in the planning. Therefore, concludes that the calculation point should not be in semidarkness zones (near the MLC), because it is what causes the most uncertainty in the independent calculation. (author)

  8. HADES. A computer code for fast neutron cross section from the Optical Model; HADES. Un programa numerico para el calculo de seccciones eficaces neutronicas mediante el modelo optico

    Energy Technology Data Exchange (ETDEWEB)

    Guasp, J.; Navarro, C.

    1973-07-01

    A FORTRAN V computer code for UNIVAC 1108/6 using a local Optical Model with spin-orbit interaction is described. The code calculates fast neutron cross sections, angular distribution, and Legendre moments for heavy and intermediate spherical nuclei. It allows for the possibility of automatic variation of potential parameters for experimental data fitting. (Author) 55 refs.

  9. Calculation of the frequency of excedence in Full Spectrum LOCA by FSR; Calculo de la Frecuencia de excedencia en Full Spectrum LOCA mediante metodologia ISA

    Energy Technology Data Exchange (ETDEWEB)

    Gomez Magan, J. J.; Queral Salazar, C.; Sanchez Perea, M.

    2012-07-01

    In this application LOCA sequences was taken into account the uncertainty in the size of rupture and the operator action times as cooling and depressurization through steam generators. The simulations were performed using the tool SCAIS, dynamically coupled with MAAP code.

  10. Calculation of the backscattering in water and compared to the values in air; Calculo del factor de retrodispersion en agua y comparativa con los valores en aire

    Energy Technology Data Exchange (ETDEWEB)

    Minano Herrero, J. A.; Sarasa Rubio, A.; Roldan Arjona, J. M.

    2011-07-01

    The purpose of this paper is to calculate values of BSF in water and comparison with data on air 11SF found in the literature. For this simulations have been performed by the Monte Carlo method for calculating values ??kerma water in the presence of a manikin of this material and in the absence thereof. The simulations were performed for monoenergetic beams in order to facilitate the calculation of the BSF for any spectral distribution of those found in the field of radiology.

  11. 76 FR 21078 - Self-Regulatory Organizations; NASDAQ OMX PHLX LLC; Notice of Filing and Immediate Effectiveness...

    Science.gov (United States)

    2011-04-14

    ... assessing an Options Surcharge Fee for RMN.\\3\\ \\3\\ RMN represents options on the one-tenth value Russell 2000 Index (the ``Reduced Value Russell Index'' or ``RMN''). The Exchange also proposes to remove... captioned, ``Equity Options Fees (Includes options overlying equities, ETFs, ETNs, HOLDRS, BKX, RUT,...

  12. Interaction and transport of cysteamine (MEA) through membrane models. {sup 15}N-NMR et {sup 1}H-NMR; Interaction et transport de la cysteamine (MEA) a travers des membranes modeles. Etude par {sup 15}N-RMN et {sup 1}H-RMN

    Energy Technology Data Exchange (ETDEWEB)

    Lagoueyte, C.; Subra, G.; Bonnet, P.A.; Chapat, J.P.; Debouzy, J.C.; Fauvelle, F.; Berleur, F.; Roman, V.; Fatome, M.; Fernandez, J.P.

    1995-12-31

    We investigated by {sup 15}N-NMR the interactions of [{sup 15}N]-MEA, a radio-protecting aminothiol, with model membranes (SUVs and LUVs) of egg yolk phosphatidylcholine and phosphatidic acid. We prepared LUVs with a pH gradient between the intravesicular space and the bulk medium. Even though the external pH was low, MEA penetrates into the vesicles. With SUVs, {sup 1}H-NMR revealed that the interactions of unlabeled MEA within the hydrophobic core of the bilayer vary with external pH value. (author). 5 refs.

  13. Etude par RMN de composés organiques contenant des chalcogènes—VIII. RMN du 13C dans la chromannone, la chromone, la coumarannone-3 et la coumarine et leurs analogues soufrés, séléniś et tellurés

    Science.gov (United States)

    Baiwir, Marcel; Llabrès, Gabriel; Christiaens, Léon; Luxen, André; Piette, Jean-Louis

    13C NMR spectra of the title compounds have been fully assigned. The results have been compared with those relative to other chalcogenated compounds, such as anisole, phenyl benzoate, benzofuran,… and their analogs. In chalcogenochromones and -coumarines, the heteroatom lone pair delocalization spreads to some extent over the heterocyclic part of the molecules, while in chalcogenochromanones and -indoxyles, it only extends to the homocycle. This electronic effect seems also to affect the heavy atom effect exhibited by Te-containing compounds.

  14. Cannabinoid antagonist in nanostructured lipid carriers (NLCs): design, characterization and in vivo study

    Energy Technology Data Exchange (ETDEWEB)

    Esposito, Elisabetta; Ravani, Laura [Department of Life Sciences and Biotechnology, University of Ferrara, I-44121 Ferrara (Italy); Drechsler, Markus [BIMF/Soft Matter Electron Microscopy, University of Bayreuth (Germany); Mariani, Paolo [Department of Life and Environmental Sciences and CNISM, Università Politecnica delle Marche, I-60100 Ancona (Italy); Contado, Catia [Department of Chemical and Pharmaceutical Sciences, University of Ferrara, I-44121 Ferrara (Italy); Ruokolainen, Janne [Department of Applied Physics, Aalto University, 00076 Aalto (Finland); Ratano, Patrizia; Campolongo, Patrizia [Department of Physiology and Pharmacology, Sapienza University of Rome, 00185 Roma (Italy); Trezza, Viviana [Department of Science, Roma Tre University, 00146 Roma (Italy); Nastruzzi, Claudio, E-mail: nas@unife.it [Department of Life Sciences and Biotechnology, University of Ferrara, I-44121 Ferrara (Italy); Cortesi, Rita [Department of Life Sciences and Biotechnology, University of Ferrara, I-44121 Ferrara (Italy)

    2015-03-01

    This study describes the preparation, characterization, and in vivo evaluation in rats of nanostructured lipid carriers (NLCs) encapsulating rimonabant (RMN) as prototypical cannabinoid antagonist. A study was conducted in order to optimize NLC production by melt and ultrasonication method. NLCs were prepared by alternatively adding the lipid phase into the aqueous one (direct protocol) or the aqueous phase into the lipid one (reverse protocol). RMN-NLCs have been characterized by cryogenic transmission electron microscopy (cryo-TEM), X-ray, photon correlation spectroscopy (PCS) and sedimentation field flow fractionation (SdFFF). Reverse NLCs were treated with polysorbate 80. RMN release kinetics have been determined in vitro by dialysis method. In vivo RMN biodistribution in rats was evaluated after intranasal (i.n.) administration of reverse RMN-NLC. The reverse protocol enabled to prevent the lost of lipid phase and to achieve higher RMN encapsulation efficacy (EE) with respect to the direct protocol (98% w/w versus 67% w/w). The use of different protocols did not affect NLC morphology and dimensional distribution. An in vitro dissolutive release rate of RMN was calculated. The in vivo data indicate that i.n. administration of RMN by reverse NLC treated with polysorbate 80 increased RMN concentration in the brain with respect to the drug in solution. The nanoencapsulation protocol presented here appears as an optimal strategy to improve the low solubility of cannabinoid compounds in an aqueous system suitable for in vivo administration. - Highlights: • Rimonabant (RMN) can be encapsulated in nanostructured lipid carriers (NLCs). • Nanoencapsulation improves RMN solubility in a stable physiologic aqueous formulation. • RMN is released in vitro from NLC by a controlled dissolutive release modality. • I.n. administration leads to higher RMN concentration in the brain with respect to plasma. • NLC increases RMN concentration in the brain with respect to

  15. Survey of shielding calculation parameters in radiotherapy rooms used in the country and its impact in the existing calculation methodologies; Levantamento de parametros de calculos de blindagem de salas de radioterapia utilizados no pais e seu impacto nas metodologias de calculo existentes

    Energy Technology Data Exchange (ETDEWEB)

    Japiassu, Fernando Parois

    2013-07-01

    When designing radiotherapy treatment rooms, the dimensions of barriers are established on the basis of American calculation methodologies specifically; NCRP Report N° 49, NCRP Report N° 51, and more recently, NCRP Report N° 151. Such barrier calculations are based on parameters reflecting predictions of treatments to be performed within the room; which, in tum, reftect a specific reality found in a country. There exists, however, a variety of modern radiotherapy techniques, such as Intensity Modulated Radiation Therapy (IMRT); Total Body Irradiation (TBl) and radiosurgery (SRS); where patierits are treated in a much different way than during more conventional treatrnents, which are not taken into account the traditional shielding calculation methodology. This may lead to a faulty design of treattnent rooms. In order to establish a comparison between the methodology used to calculate shielding design and the reality of treatments performed in Brazil, two radiotherapy facilitie were selected, both of them offering traditional and modern treatment techniqued as described above. Data in relation with reatments perfotmed over a period of six (6)months of operations in both institutions were collected. Based on tlis informaton, a new set of realistic parameters required for shielding design was estãblished, whicb in turn allowed for a nwe caculation of barrier thickness for both facilities. The barrier thickness resultaing from this calculation was then compared with the barrier thickness propose as part of the original shielding design, approved by the regulatory authority. First, concerning the public facility, the thickness of all primary barriers proposed in the shielding design was actually larger than the thickness resulting from calculations based on realistic parameters. Second, concerning the private facility, the new data show that the thickness of three out of the four primary barriers described in the project is larger than the thickness oresulting from calculation based on current operating conditions. When it comes to thickness of secondary barriers, calculations based on averages of treatments over six months show results below the proposed thicknesses in the shielding design of the public facility. However, data reflecting the most extreme situations observed in routine operations how that the thickness proposed in the design project does not meet hielding requirements. In the private facility, more conservative estimates were used in the shielding design, which resultedin suitable barrier thickness in both normal and extreme operation conditions. In fact, the actual barrier thicknesis in average 31 cm greater than the ehickness required by the reality-based data. The primary barrier thickness resulting from reality-based calculations supports the assumption than smaller primary barrier thickness is required in facilities using modern techniques of radiation therap, as opposed to thickness requirements in facilities that only uses conventional treatment techniques. The hypothesis of increased thickness requirements for secondary barriers of installations using IMRT was confirmed by data obtained from the public facility. The results obtained from the private facility denote that the addition of conservative factors in the calculation method will produce barriers suitable for both average and extreme conditions of accelerator usage. However, corresponding increased costs must also be considered. (author)

  16. Analysis of uncertainties, associated to the calculating hypothesis, in discharge tables for high flows estimating, based on mathematics models for calculating water surface profiles fore steady gradually varied flow; Analisis de las incertidumbres, asociadas a las hipotesis de calculo, en la estimacion de curvas de gasto para crcidas, basada en el empleo de modelo matematico de calculo hidraulico en regimen permanente

    Energy Technology Data Exchange (ETDEWEB)

    Aldana Valverde, A. L.; Gonzalez Rodriguez, J. C.

    1999-08-01

    In this paper are analyzed some of the most important factors which can influence on the results of calculating water surface profiles for steady gradually varied flow. In this case, the objective of this kind of modeling, has been the estimation of discharges tables for high flows of river station gages connected to the hydrologic automatic information system (SAIH) of the Confederacion Hidrografica del Sur de Espana, system named red Hidrosur. (Author) 3 refs

  17. The use of stochastic method for the calculation of liquid-vapor multicomponent equilibrium and the contribution of groups theory for the evaluation of fugacity coefficient; Uso de um metodo estocastico para calculo do equilibrio liquido-vapor de sistemas multicomponentes e avaliacao de uma abordagem por contribuicao de grupos para o calculo do coeficiente de fugacidade

    Energy Technology Data Exchange (ETDEWEB)

    Cavalcanti, Rafaelly L.; Oliveira, Jackson A. [Universidade Federal do Rio Grande do Norte (UFRN), Natal, RN (Brazil). Dept. de Engenharia Quimica; Rojas, Leopoldo O.A. [Centro de Tecnologias do Gas (CTGAS), Natal, RN (Brazil)

    2008-07-01

    This work has the main objective of evaluating the mathematical model developed by Jaubert e Mutelet (2004) in terms of the prediction capacity for the calculation of the vapor-liquid equilibrium (VLE). This model is based on Peng-Robinson equation of state (EOS) and it considers the binary interaction parameters (Kij(T)) estimated by a contribution group method and dependent of the temperature. The model proposed by Jaubert e Mutelet (2004), named PPR78 (Predictive Peng-Robinson), was implemented in this work by using the Fortran language. An optimization approach based on the stochastic algorithm of Particle Swarm Optimization (PSO) was used in order to calculate the vapor-liquid equilibrium. Simulations were accomplished for several binary systems and the results were concordant with some experimental data of the investigated systems. However, for some systems different from those presented by Jaubert and Mutelet (2004), the model presented low prediction capacity. In spite of the great demand of computational performance, the algorithm PSO demonstrated robustness during the calculation of VLE and it assured convergence in most of the cases. (author)

  18. Over-expression of corticotropin-releasing factor mRNA in inferior olivary neurons of rolling mouse Nagoya.

    Science.gov (United States)

    Sawada, Kazuhiko; Kawano, Michihiro; Tsuji, Hiroshi; Sakata-Haga, Hiromi; Hisano, Setsuji; Fukui, Yoshihiro

    2003-10-01

    Expression of corticotropin-releasing factor (CRF) mRNA was examined in the inferior olivary nucleus (ION) of an ataxic mutant, rolling mouse Nagoya (RMN) by semi-quantitative in situ hybridization. The most marked difference in the level of CRF mRNA signals between RMN and non-ataxic littermates (control mice) was observed in the beta-subnucleus and ventrolateral protrusion of the ION. The level of signals in these subnuclei was about twofold higher in RMN than in the controls. Signal levels in the dorsal nucleus, principal nucleus and subnucleus A were slightly but significantly higher in RMN than in the controls. In the other subnuclei, there were no differences in signal level between RMN and controls. These results suggest a region-related over-expression of CRF mRNA in the ION of RMN. This may be responsible for the increased sensitivity of some Purkinje cells to glutamate, resulting in ataxic symptoms of RMN.

  19. Scattering and Propagation in Random Media

    Science.gov (United States)

    1988-01-01

    analyasur do front Wondo. Lintenait6 a2,(r) data la pupill* 3o calculo & partir des danukea issues Vun aaaalysour do Hartmsar-Shack come Ie moyonnne des...harmoniques apatileux at 1cmn suppose done lax calculo quo Is ,-ugositli d, la, surface eat intdrleurea Isb imgueur d’ando do champ, dlectromaqndtique in’ýLdent...k 10 An(P.z)dx (3) an eat Is fluctuation do lindico du milieu caus~o par Ion variations do I& donsito Glectroniquo ANg. an so calculo do I& faqon

  20. Theorical and experimental study of the induced forces by the mixed, divergent, convergent and straight labyrinth of seal systems on the steam turbines, gas turbines and compressor rotors; Estudio teorico-experimental de las fuerzas inducidas por los sistemas de sellos de laberinto rectos, convergentes, divergentes y mixtos sobre los rotores de turbinas de vapor, turbinas de gas y compresores

    Energy Technology Data Exchange (ETDEWEB)

    Salazar San Andres, Octavio Ramon

    1991-12-31

    A theoretical and experimental research is conducted in order to determine the labyrinth seal forces, as well as the stiffness and damping coefficients for straight, convergent, divergent, and combined shapes on turbine and compressor rotors. The mathematical model is deduced on the basis of the single volume method and its solution is obtained by the perturbation procedure. The validation is achieved with published results. Experimental work carried out on a test bench is described in the text. This involved labyrinth seals with straight, convergent, and divergent profiles, as the published information relating to mixed type is sufficient to perform the evaluation. The conclusions demonstrate that the model is able to predict and determine the performance of labyrinth seals based on forces and rotordynamic coefficients for static and dynamic motions. Finally, tests on real steam turbines of 300 MW are recommended. In this case the high pressures and use of wheels with strips on the periphery and supported by the upper part of blades, increase the susceptibility of self excited subsynchronous vibrations. [Espanol] Se presenta una investigacion teorica-experimental relacionada con la obtencion y validacion de un modelo matematico capaz de predecir las fuerzas y los coeficientes de rigidez y amortiguamiento de los sellos de laberinto de tipo recto, convergente, divergente y mixto que se emplean en turbinas y compresores tanto terrestres como aereos. El modelo matematico propuesto se deduce a partir del metodo de un solo volumen y su solucion se obtiene a traves de metodos perturbatorios. La validacion del mismo se consigue al comparar con resultados experimentales publicados en revistas especializadas y con los datos medidos en un banco de pruebas cuya descripcion se incluye en el trabajo, cualculado para sellos rectos, convergentes y divergentes, ya que la informacion publicada respecto al tipo mixto o combinado es suficiente. Las conclusiones de la investigacion demuestran que el modelo es capaz de dar una vision cualitativa y cuantitativa de las fuerzas y los coeficientes de rigidez y amortiguamiento de los sellos de laberinto con las geometrias antes mencionadas, tanto para el rotor estatico como en operacion. Por otra parte se recomienda llevar a cabo mas experimentacion con equipo instalado en plantas termoelectricas y en especial en turbinas de vapor con capacidades iguales o superiores a los 300 MW, donde las altas presiones y los sellos localizados en la parte superior de los alabes, vuelven mas susceptibles a las maquinas para autoinducir vibraciones subsincronas.

  1. A theoretical quantum study on the distribution of electrophilic and nucleophilic active sites on Cu(100) surfaces modeled as finite clusters; Un estudio teorico cuantico sobre la distribucion de sitios activos electrofilicos y nucleofilicos sobre superficies de Cu(100) modeladas como cumulos finitos

    Energy Technology Data Exchange (ETDEWEB)

    Rios R, C.H.; Romero R, M. [Universidad Autonoma Metropolitana-Azcapotzalco, Departamento de Materiales, Av. San Pablo 180, Col. Reynosa Tamaulipas, 02200 Mexico D.F. (Mexico); Ponce R, A.; Mendoza H, L.H. [Universidad Autonoma del Estado de Hidalgo, Centro de Investigaciones Quimicas, Carretera Pachuca-Tulancingo km. 4.5, 42181 Pachuca, Hidalgo (Mexico)]. e-mail: clara_hrr@yahoo.es

    2008-07-01

    In this work, it is shown a theoretical quantum study of the active sites distribution on a monocrystalline surface of Cu(100). The copper surface was modeled as finite clusters of 14, 23, 38 and 53 atoms. We performed Hartree-Fock and Density Functional Theory (B3LYP) ab initio calculations employing the pseudopotentials of Hay and Wadt (LANLlMB y LANL2DZ). From calculations, we found a work function value of 4.1 eV. The mapping of the HOMO and LUMO in the frozen core approximation, allowed us finding the electrophilic and nucleophilic active sites distribution, respectively. The results indicated that electrophilic sites on the Cu(100) surface were located on hollow position and its numerical density was 8.6 x 10{sup 16} sites cm{sup -2}. From the nucleophilic local softness study, it was found that the nucleophilic sites were formed by a group of atoms and it had a numerical density of 2.4x 10{sup 16} sitescm{sup -2} . Last results indicated that adsorptions with 2 x 2 and 3 x 3 distributions can be favored onto a Cu(100) surface for the electrophilic and nucleophilic cases, respectively. (Author)

  2. Community and corporate social responsibility in sector of oil, gas and mining: short approach considering practice and theory aspects; Responsabilidade social corporativa e comunitaria nos setores de petroleo, gas e mineracao no Brasil: breve reflexao sobre a evolucao teorico-pratica

    Energy Technology Data Exchange (ETDEWEB)

    Carvalho, Edison D.R.; Danciguer, Lucilene; Macarini, Samuel; Pereira, Maira de S.; Lopes, Luciano E. [GAIA - Grupo de Aplicacao Interdisciplinar a Aprendizagem (GAIA), Campinas, SP (Brazil)

    2008-07-01

    The evolution of the debate about corporate and community social responsibility has been happening, in Brazil, with the implementation of programs for the quality of services and products; the improvement of the performance of activities related to environmental conservation, the increase in security and health of workers and communities; the intensification of communication and relationship with workers, communities, and other stakeholders. This work discusses the evolution of this culture in petroleum, gas and mining sectors in Brazil during the last 20 years. It was based on the experience of the Interdisciplinary Learning Application Group (GAIA) with both, the internal public (including all employees) and the communities directly or indirectly affected by old or new activities. The cases analyzed are good examples of this cultural change, which prioritizes the development of humanist and progressive approaches to corporate education. The results GAIA obtained actuating during the last 15 years in partnership with corporations from several sectors evidenced that the incorporation of social responsibility objectives and targets as part of corporation's business brought benefits for all stakeholders. To the managers it brought an improvement in administration considering the stakeholders. To the workers it helped developing their self-esteem and citizenship. To the communities it enhanced their capacity to dialogue and created sustainable initiatives that improve their quality of life. (author)

  3. Analysis of the principal factors preventing the reaching of optimal theoretical values in the working of some coalfields in N. E. Spain. Analisis de los principales factores que impiden alcanzar el optimo teorico en la explotacion de algunas cuencas carboniferas del N. O. de Espana

    Energy Technology Data Exchange (ETDEWEB)

    Garcia Garcia, M. (Universita de Oviedo, Oviedo (Spain). Dpto. de Explotacion y Prospeccion de Minas)

    1988-01-01

    With the Spanish admission to the E.E.C. the Spanish coal mines need to improve their competitivity with a more perfect planning removing several opposite factors. A analysis of these factors is made: (1) The distribution and size of the mining property. (2) The economical capacity of the mining companies. (3) The economic policy of the companies. (4) The limited information. (5) The bureaucratic difficulties. The first factor is the most important and the reason for the second and third, and the two last have not too much influence. 2 figs., 1 tab.

  4. Reaction of 5-amino-8-hydroxy-1,4 naphthoquinone with aliphatic and aromatic amines. Theoretical study of its tantomeric equilibria and reactivity; Reaccion de la 5-amino-8-hidroxi-1,4-naftoquinona con aminas alifaticas y aromaticas. Estudio teorico de su equilibrio tantomerico y reactividad

    Energy Technology Data Exchange (ETDEWEB)

    Franceschini, F.C. [Departamento de Quimica Organica, Instituto de Quimica UFRGS Porto Alegre (Brazil); Sanchez Alonso, F.; Stefani, V. [Instituto de Quimica Organica General, CSIC, Madrid (Spain)

    1995-12-31

    The reaction of 5-amino-8-hydroxy-1,4-naphthoquinone (1) with aliphatic and aromatic amines have been studied, in absence or present of copper (II) salts, in order to prepare diamino hydroxy-1,4-naphthoquinones. Also a quantum mechanics calculation on 1 have been done for studying its tautomeric equilibria and rationalizing its behaviour in the reaction with amines. (Author) 32 refs.

  5. Balance del referendo sobre el TLC en Costa Rica a la luz de la teoria de la democracia

    National Research Council Canada - National Science Library

    Raventos, Ciska

    2008-01-01

    ...) realizado en Costa Rica el 7 de octubre de 2007. En terminos teoricos busco situar los aportes de la teoria de la democracia participativa para enriquecer la perspectiva de la democracia representativa...

  6. Inversion en entrenamiento en el empleo: una revision de la literatura

    National Research Council Canada - National Science Library

    Yanez Contreras, Martha; Acevedo Gonzalez, Karina

    2012-01-01

    ...: el entrenamiento en el empleo. El analisis de la literatura sobre entrenamiento en el empleo permite evidenciar que los mayores desarrollos teoricos se han adelantado en el analisis de quien asume los costos del entrenamiento...

  7. Lo politico de las politicas de salud sexual y reproductiva para jovenes en Colombia

    National Research Council Canada - National Science Library

    Morales-Borrero, Maria Carolina

    2010-01-01

    En este articulo se presenta el enfoque teorico-metodologico construido para el analisis de las politicas de salud sexual y reproductiva para jovenes en Colombia, como resultado de una tesis doctoral sobre el tema...

  8. Vivienda, teoria y practica. Treinta anos de experiencia academica en La Habana

    National Research Council Canada - National Science Library

    Gonzalez Couret, Dania

    2012-01-01

    ..., en el presente trabajo se valora la evolucion del pensamiento academico sobre el tema de la vivienda, materializado en los enfoques teoricos y metodologicos desarrollados en la Facultad de Arquitectura...

  9. Fundamentos hipoteticos para investigar la crisis economica contemporanea

    National Research Council Canada - National Science Library

    Soto, Sergio Reuben

    2012-01-01

    El articulo pretende integrar los desarrollos teoricos en el campo de los mercados imperfectos y monopolicos, y el funcionamiento de la firma en tales condiciones, con las teorias de la distribucion del ingreso...

  10. La practica de la arquitectura como racionalizacion sistemica

    National Research Council Canada - National Science Library

    Villate, Camilo; Tamayo, Brando

    2010-01-01

    ... de diseno con relacion a los multiples requerimientos implicitos de la arquitectura. Para contrarrestar este reduccionismo es preciso recurrir a la construccion de modelos teoricos que permitan evidenciar el significada de disenar un edificio...

  11. Cartografias del campo politico afrodescendiente en America Latina

    National Research Council Canada - National Science Library

    Lao-Montes, Agustin

    2009-01-01

    .... Luego de establecer una serie de criterios teoricos, metodologicos para el analisis historico de los movimientos negros en la modernidad y de los movimientos afroamericanos en particular, el articulo...

  12. Como integrar las nuevas tecnologias en educacion inicial?

    National Research Council Canada - National Science Library

    Martinez, Jeanette

    2011-01-01

    .... El presente ensayo busca contribuir al analisis tematico del mismo, exponiendo una serie de ideas y reflexiones teorico-practicas para lograr una integracion adecuada de las nuevas tecnologias al...

  13. De la apologia al triste cantar: la evaluacion de la Conquista de Mexico en las piezas teatrales de John Dryden y Fernando de Zarate

    National Research Council Canada - National Science Library

    Nunez-Ronchi, Ana

    2012-01-01

    .... Recurriendo al aparato teorico-metodologico de la semantica interpretativa, este trabajo se propone comparar la vision inglesa y la espanola de la conquista de Mexico en dos piezas de teatro europeas...

  14. La gestion por la innovacion tecnologica desde las patentes universitarias

    National Research Council Canada - National Science Library

    Zaldivar-Castro, Antonio Bernabe; Oconnor-Montero, Lierli

    2012-01-01

    ... productivo de las invenciones gestadas. El trabajo tiene como objetivo elaborar una propuesta teorico-metodologica en la generacion de innovaciones hacia los sectores economicos, desde el analisis de las invenciones protegidas...

  15. Caracterizacion morfometrica de un sistema fluviolacustre tropical, Antioquia, Colombia

    National Research Council Canada - National Science Library

    Montoya Moreno, Yimmy

    2008-01-01

    Se describen las caracteristicas batimetricas y morfometricas de un lago tropical somero y las predicciones de caracter teorico derivadas de los analisis de los parametros morfometricos y de los elementos de forma...

  16. Ser o estar "queer" en Latinoamerica? El devenir emancipador en: Lemebel, Perlongher y Arenas

    National Research Council Canada - National Science Library

    Arboleda Rios, Paola

    2011-01-01

    ... rebeldes para re-imaginar el proyecto queer latinoamericano. Sus creaciones contestan los modelos importados tanto de analisis teorico como de formas de ser disidente y reivindican la importancia social del amor...

  17. Factores que influyen en el consumo sustentable de productos organicos en el Noroeste de Mexico

    National Research Council Canada - National Science Library

    Salgado-Beltran, L; Beltran-Morales, L.F

    2011-01-01

    ... en el consumo sustentable de productos organicos en el noroeste de Mexico. Para ello, el modelo teorico fue definido por medio de la revision de literatura y se diseno un instrumento de medicion...

  18. Como predecir la perpetracion adolescente del ciberacoso escolar: aplicacion de la Teoria de la Conducta Planificada

    National Research Council Canada - National Science Library

    Heirman, Wannes; Walrave, Michel

    2012-01-01

    El objetivo de este estudio es contribuir al campo de investigacion del ciberacoso escolar mediante un marco teorico exhaustivo que ayude a predecir la perpetracion del ciberacoso escolar en adolescentes. Participaron...

  19. Vision general de las practicas de capacitacion en Peru

    National Research Council Canada - National Science Library

    Hernandez Pozas, Olivia; Lourdes Jauregui, Kety

    2012-01-01

    .... Este articulo tambien ayuda a establecer prioridades de investigacion futura. La Teoria de Capital Humano y contribuciones de evaluacion de necesidades, planeacion, implantacion y evaluacion de la capacitacion sirvieron como marco teorico...

  20. La Didactica de la Lengua y la Literatura orientada a la inclusion: el desarrollo de una prueba de evaluacion de la disfemia

    National Research Council Canada - National Science Library

    Lopez Valero, Amando; Veas Iniesta, Francisco; Lopez Lopez, Maria

    2008-01-01

    .... Dentro del marco teorico que supone la educacion inclusiva se trata de realizar un planteamiento adecuado para, desde la Didactica de la Lengua y la Literatura, tratar de desarrollar una prueba...

  1. Estrategias economicas y politicas de las grandes empresas alimenticias privadas venezolanas y sus efectos en trabajadores, consumidores y pequenas empresas

    National Research Council Canada - National Science Library

    Gamboa Caceres, Teresa; Melean Romero, Rosana; Lopez Valladares, Mirtha

    2008-01-01

    A partir de un estudio teorico-practico, con base en analisis de documentos, entrevistas y observacion directa, se exploran las estrategias economicas y politicas de grandes empresas alimenticias en Venezuela...

  2. Pensar a la audiencia transnacional: comunicacion de masas en la etapa posnacional

    National Research Council Canada - National Science Library

    Moreno Esparza, Gabriel Alberto

    2011-01-01

    El articulo argumenta que las categorias de analisis de la era de la comunicacion de masas permanecen vigentes --pese a la descalificacion de aportes teoricos sobre los nuevos medios--, para explicar...

  3. Argumentacion o demostracion en la decision judicial? Una mirada en el Estado constitucional

    National Research Council Canada - National Science Library

    Aguirre Roman, Javier Orlando, Garcia Obando, Pedro Antonio, Pabon Mantilla, Ana Patricia

    2009-01-01

    .... Para orientar la solucion del problema se revisara un marco teorico con el que se pretende sustentar la tesis segun la cual la argumentacion en las decisiones judiciales, mas que la demostracion, es...

  4. An increased expression of Ca(2+) channel alpha(1A) subunit immunoreactivity in deep cerebellar neurons of rolling mouse Nagoya.

    Science.gov (United States)

    Sawada, K; Sakata-Haga, H; Ando, M; Takeda, N; Fukui, Y

    2001-12-01

    Rolling mouse Nagoya (RMN) is an ataxic mutant and carries a mutation in the gene coding for the alpha(1A) subunit of the P/Q-type Ca(2+) channel. We examined the immunohistochemical expression of the alpha(1A) subunit in deep cerebellar nuclei of RMN. The antibody used recognized residues 865-883 of the mouse alpha(1A) subunit not overlapping the altered sequences in RMN. In RMN, many neurons exhibited definite alpha(1A) subunit-staining in the medial nucleus, interposed nucleus, and lateral nucleus of deep cerebellar nuclei. The number of positive neurons in these nuclei was significantly higher in RMN than in controls. Increased expression of the alpha(1A) subunit in deep cerebellar neurons might compensate for the altered function of the P/Q-type Ca(2+) channel of RMN.

  5. Energy efficiency study of the domestic refrigerators inside of a controlled environment laboratory; Estudio de la eficiencia energetica de refrigeradores domesticos dentro de un laboratorio de ambiente controlado

    Energy Technology Data Exchange (ETDEWEB)

    Arroyo Cabanas, Fernando Gabriel

    2004-04-15

    The evaluation of the energy saving potential is looked for that exists in the park of domestic refrigerators of the country when replacing them by refrigerators of higher power efficiency, through a comparative analysis of the results obtained in experimental tests applied to domestic refrigerators, in agreement with Official Norm NOM 015-2002 and with the theoretical values reported by the manufacturers. Initially the park of domestic refrigerators used in Mexico (brand names, efficiency and electrical consumption) was studied with the objective of evaluating the electric energy consumption in the refrigerators at national level. Once with the consumption determined, a governmental program for the accelerated substitution of the park of domestic refrigerators of greater antiquity is proposed, for models of better power efficiency. Next, the characterization of the Laboratorio de Ambiente Controlado is made (preliminary tests of thermal stability and heat losses) to obtain the thermal conditions marked by Norm NOM-015-2002. Also relevant points for the experimental energy analysis are established in domestic refrigerators according to norm NOM-015-2002. Finally, a test protocol for domestic refrigerators applied in the LAC with base in this norm will be proposed and a validation of this by means of the necessary experimental tests and the required calculations will be carried out. Finally the obtained results of the tests of power efficiency applied to different models from domestic refrigerators, as well as conclusions are presented. [Spanish] Se busca evaluar el potencial de ahorro de energia que existe en el parque de refrigeradores domesticos del pais al sustituirlos por refrigeradores de mayor eficiencia energetica, a traves de un analisis comparativo de los resultados obtenidos de pruebas experimentales aplicadas a refrigeradores domesticos, de acuerdo con la Norma Oficial NOM.015-2002 y con los valores teoricos reportados por los fabricantes. Primeramente

  6. Current shaper: a new topology; Conformador de corriente: una nueva topologia

    Energy Technology Data Exchange (ETDEWEB)

    Lopez Salcedo, Josue

    2003-03-15

    el puente rectificador -en lugar de tener una conexion en serie con el puente-, denominado Conformadores de Corriente Tipo Paralelo. Se describe la teoria de la operacion y el analisis matematico de las formas de onda de la topologia de este nuevo conformador de corriente junto con el analisis teorico que determina la eficacia del sistema y las consideraciones en el diseno de la topologia. En lo referente al diseno de la etapa de potencia se presenta el filtro EMI empleado, el calculo del capacitor voluminoso, el convertidor flyback y del transformador, asi como el tipo de compensador utilizado en la parte de la etapa de control. Para corroborar el analisis de la forma de onda de la corriente de entrada se implemento un prototipo a una potencia de salida de 50W, cuyos resultados experimentales se muestran a la par del contenido armonico de la corriente de entrada necesaria para cumplir con la norma de calidad y los resultados a la respuesta dinamica del convertidor.

  7. A determination of the greenhouse parameter for dry and unpolluted air

    Energy Technology Data Exchange (ETDEWEB)

    Penaloza M, Marcos A. [Universidad de Los Andes, Facultad de Ciencias, Departamento de Fisica, Merida, (Venezuela)

    1996-04-01

    The relative extinction of solar and infrared radiation by dry and clean air molecules, has been estimated through a theoretical determination of the ratio referred ordinarily as the Greenhouse Parameter (GP). In a first approach, it was calculated assuming that terrestrial air only consists of a simple mixture of oxygen and nitrogen. The method used here is based on the application, in an inverse procedure, of an homogeneous, plane-parallel, and time-independent grey model, which employs the Eddington approximation as a solution to the radiative transfer equation, both in the solar and the infrared spectral regions and, which has the GP value as an input free parameter. The best value of the GP was estimated calibrating the local temperature profile for four types of uniform surface (snow, desert, vegetation and ocean), with average albedos known in these spectral regions, adopting air surface temperature values which were chosen for an assumed micro or local climatological environment according to an average radiative criterion. With this result, it was possible for an estimation of the infrared opacity for the air layer implicated in this model and also the mean extinction coefficient in this spectral range to be calculated. The results predicted are compared with results obtained indirectly from the data provided by other authors. Although its validation is constrained solely to the radiative model applied it seems that the value of the GP obtained is more accurate than the one initially available. [Spanish] La extincion relativa de radiacion por moleculas de aire limpio y seco, tanto en la region espectral solar como en la infrarroja, ha sido estimada a traves del calculo teorico de un parametro conocido en general como Parametro de Invernadero (PI). En una primera aproximacion, este parametro fue calculado considerando el aire terrestre como una mezcla simple de oxigeno y nitrogeno solamente. El metodo usado aqui se baso en la aplicacion, bajo un

  8. Characterization of the billow applied to Tuxpan, Veracruz; Caracterizacion del oleaje aplicada a Tuxpan, Veracruz

    Energy Technology Data Exchange (ETDEWEB)

    Rosales Sierra, Victor

    1999-07-01

    In this work, the criteria for the wave temporal and spectral statistical analysis were reviewed. These analysis are applied to the site Tuxpan, Veracruz, in the Mexican Gulf coast. In the temporal statistic analysis, the high (Rayleigh, Tayfun and Carter) and period (Bretchneider, Cavanie and Longuet-Higgins) theoretic probability distributions are compared with field data from Tuxpan. In the other hand, in the frequency domain analysis, the theoretic spectrums (Bretchneider-Mitsuyasu, Jonswap-Hasselmann, Pierson-Moscowitz, Neumann, ITTC, ISSC, TMA and Ochi-Hubble) are compared with the one obtained from Tuxpan measurements, then changes are made to some spectrums in order to better couple to field data. Finally, some recommendations are made to improve the wave data acquisition and analysis methods. From the study results, it's important to mention that the Tayfun high probability distribution and the Cavanie period probability distribution better fit Tuxpan field data. In the spectral analysis, the Bretchneider spectrum, modified by Mitsuyasu, better coupled to the spectrum obtained from Tuxpan field data. In the temporal statistical analysis, correct the mean level using the parabolic approximation, in order to eliminate the tidal and long period wave effects, it is recommended. For the registered individual wave calculus the zero up cross method was used. [Spanish] En este trabajo se revisan los criterios para el analisis estadisticos temporal y espectral del oleaje, mismos que son aplicados para la caracterizacion del oleaje en Tuxpan, Veracruz. En cuanto al analisis estadistico temporal, se comparan las distribuciones teoricas de probabilidad de altura de Rayleigh, Tayfun y Carter; y las de periodo de Bretchneider, Cavanie y Longuet-Higgins contra las resultantes de las mediciones en campo. Por otro lado y concerniente al analisis en el dominio de la frecuencia, se comparan los espectros teoricos de Bretchneider- Mitsuyasu, Jonswap-Hasselmann, Pierson

  9. Determination of unreacted monomers in restorative dental resins based on dimethacrylate by NMR hydrogen; Determinacao do teor de monomero residual em resinas restauradoras a base de dimetacrilatos por RMN de hidrogenio

    Energy Technology Data Exchange (ETDEWEB)

    Correa, Ivo Carlos; Miranda Junior, Walter G. [Sao Paulo Univ., SP (Brazil). Faculdade de Odontologia. Dept. de Materiais Dentarios]. E-mail: ivo@fo.usp.br; Tavares, Maria Ines B. [Universidade Federal, Rio de Janeiro, RJ (Brazil). Inst. de Macromoleculas]. E-mail: mibt@ima.ufrj.br

    2001-07-01

    The presence of unreacted monomers after photo-activation of dental composites causes mechanical and biological properties to decrease and could be detected by NMR analysis. The aim of this study was to evaluate the percentage of leachable monomers of light-cured composites under the effect of variations of exposure time of photo activation by nuclear magnetic resonance of hydrogen in solution (NMR{sup 1}H). The composite resins tested Z250 and Fill Magic obtained similar values of unreacted monomers (%) at photo curing time suggested by the manufacturer and values were also lower than Durafill and A110 concentrations. From the NMR results, one day extractable time was efficient to quantify the amount of residual monomers in the dental composites tested, unless for Durafill composite. (author)

  10. Evaluation of natural rubber from IAC series clones by solid state {sup 13}C NMR; Avaliacao da borracha natural de clones da serie IAC por {sup 13}C RMN no estado solido

    Energy Technology Data Exchange (ETDEWEB)

    Martins, Maria A.; Moreno, Rogerio M.B.; Goncalves, Paulo S. [Instituto Agronomico de Campinas, SP (Brazil). Centro de Cafe e Plantas Tropicais. Programa Seringueira]. E-mails: paulog@iac.sp.gov.br; mariaalice@cnpdia.embrapa.br; Forato, Lucimara A.; Colnago, Luiz A.; Mattoso, Luiz H.C. [EMBRAPA Instrumentacao Agropecuaria, Sao Carlos, SP (Brazil)]. E-mail: colnago@cnpdia.embrapa.br; forato@cnpdia.embrapa.br; rogerio@cnpdia.embrapa.br; mattoso@cnpdia.embrapa.br; Job, Aldo E. [Universidade Estadual Paulista (UNESP), Presidente Prudente, SP (Brazil). Departamento de Fisica, Quimica e Biologia

    2005-07-01

    Agronomic Institute (IAC) and EMBRAPA Agricultural Instrumentation (EMBRAPA/CNPDIA) have been studied Hevea species in order to increase the production of the natural rubber and to develop new clones more appropriated to Brazil's soil and climate. Structural characterization of natural rubber [Hevea brasiliensis (Willd. ex Adr. de Juss.) Muell. - Arg.] from new clones of the IAC series (IAC 300, 301, 302, 303, 35, 40, and 56) and from RRIM 600 clone has been studied by high-resolution solid-state {sup 13}C NMR and by single pulse technique. The results have shown that the application of solid-state {sup 13}C NMR using the single pulse technique is a powerful tool to study natural rubber. The spectra obtained through this technique confirmed that natural rubber from all clones studied are cis-1,4-polyisoprene (author) form.(author)

  11. NMR studies of the molecules dynamics to the solid-liquid interfaces: from graded porous materials to oil rocks; Etudes RMN de la dynamique des molecules aux interfaces solide-liquide: des materiaux poreux calibres aux roches petroliferes

    Energy Technology Data Exchange (ETDEWEB)

    Godefroy, S.

    2001-11-01

    Low field NMR relaxation for laboratory or in-situ applications provides critical information for oil recovery such as porosity, saturation, and permeability of rocks. In addition, pore size distribution and wettability can also be obtained in some cases. The technique relies on the measurement of proton longitudinal (T{sub 1}) or transverse (T{sub 2}) nuclear relaxation times. For better predictions, the surface micro-dynamics and the chemical properties of the liquids entrapped in the pore space are important and must be characterized. It is well known that the NMR relaxation is enhanced by the paramagnetic impurities at the pore surface but many other parameters influence the relaxation time distributions. These parameters are used to derive the petrophysical properties of the rocks. We propose here an original method to probe the dynamics of water and oil at the pore surface. In the present study, we used both nuclear relaxation at 2.2 MHz and field cycling Nuclear Magnetic Relaxation Dispersion (NMRD) techniques. We applied these two techniques to different kinds of water or oil saturated macroporous media (grain packings, outcrop and reservoir rocks with SiO{sub 2} or CaCO{sub 3} surfaces). We studied the dependence of NMR relaxation on pore size, magnetic field and temperature. Varying the pore size and the surface density of paramagnetic impurities of water saturated grain packings allowed experimental evidence for the two limiting regimes of the water relaxation in pores (surface- and diffusion-limited regimes). NMRD technique (evolution of 1/T{sub 1} with the magnetic field) allowed us to probe liquid surface dynamics in water or oil fully saturated grain packing, outcrop rocks or reservoir rocks (water- and oil-wet surfaces). We evidenced a two-dimensional molecular surface diffusion and directly estimated important parameters such as correlation times, residence times and molecular self-diffusion on the surface. Finally, we proved that the temperature dependence of T{sub 1} and T{sub 2} is directly related to the surface chemistry of the rocks. Such a dependence is clearly important for oil field in-situ measurements (well logging). (author)

  12. Characterization of soybean phosphatidylcholine purity by {sup 1}H and {sup 31}P NMR; Caracterizacao da pureza de fosfatidilcolina da soja atraves de RMN de {sup 1}H e de {sup 31}P

    Energy Technology Data Exchange (ETDEWEB)

    Mertins, Omar; Sebben, Marcelo; Schneider, Paulo Henrique; Pohlmann, Adriana Raffin; Silveira, Nadya Pesce da [Universidade Federal do Rio Grande do Sul (UFRGS), Porto Alegre, RS (Brazil). Dept. de Quimica]. E-mail: nadya@iq.ufrgs.br

    2008-07-01

    A strategy is proposed to evaluate the purity of phosphatidylcholine from soybean lecithin, obtained by extraction or column chromatography, using the integrals ratio of {sup 1}H NMR spectra. Integrals of methylene signals, around 1.3 and 1.6 ppm, are added and divided by the integral of the choline methyl groups, around 3.3 ppm. Before purification, a ratio of 19.68 {+-} 1.37 was determined. Using extraction, a ratio of 10.70 {+-} 0.61 was found, while from column chromatography, a value of 2.99 {+-} 0.25 was detected. {sup 31}P NMR of standard phosphatidylcholine showed signals at -0.2 and -0.9 ppm, whereas the purified one showed a single signal at -0.9 ppm. (author)

  13. Caracterização da pureza de fosfatidilcolina da soja através de RMN de ¹H e de 31P Characterization of soybean phosphatidylcholine purity by ¹H and 31P NMR

    Directory of Open Access Journals (Sweden)

    Omar Mertins

    2008-01-01

    Full Text Available A strategy is proposed to evaluate the purity of phosphatidylcholine from soybean lecithin, obtained by extraction or column chromatography, using the integrals ratio of ¹H NMR spectra. Integrals of methylene signals, around 1.3 and 1.6 ppm, are added and divided by the integral of the choline methyl groups, around 3.3 ppm. Before purification, a ratio of 19.68±1.37 was determined. Using extraction, a ratio of 10.70±0.61 was found, while from column chromatography, a value of 2.99±0.25 was detected. 31P NMR of standard phosphatidylcholine showed signals at -0.2 and -0.9 ppm, whereas the purified one showed a single signal at -0.9 ppm.

  14. Palm oil based polymer materials obtained by romp: study by low field NMR; Materiais polimericos obtidos via ROMP a partir de oleo de palma: estudo por RMN de baixo campo

    Energy Technology Data Exchange (ETDEWEB)

    Fernandes, Henrique; Lima-Neto, Benedito S., E-mail: benedito@iqsc.usp.br [Universidade de Sao Paulo (USP), Sao Carlos, SP (Brazil). Instituto de Quimica de; Azevedo, Eduardo R. de [Universidade de Sao Paulo (USP), Sao Carlos, SP (Brazil). Instituto de Fisica

    2013-07-01

    Aiming to study and develop new materials synthesized from sustainable sources, several polymers were prepared using in its monomeric composition, different amounts of NPO (Norbornenyl Palm Oil) monomer. This monomer was developed based on a vegetable oil rather produced in northern Brazil, the Palm Oil. Since this oil have a low content of unsaturation, its use in developing new monomer for ROMP (Ring-Opening Metathesis Polymerization) is not exploited. In this regard, polymeric materials were obtained using the NOP and both the reaction process and the resulting products were analyzed by Nuclear Magnetic Resonance in the time domain (TD-NMR) at low magnetic field. (author)

  15. LF-NMR study of effect the octadecylamine addition in the copolymerization process between acrylic acid and styrene monomers; Estudo por RMN de baixo campo do efeito da adicao de octadecilamina na copolimerizacao dos monomeros de acido acrilico e estireno

    Energy Technology Data Exchange (ETDEWEB)

    Pedroza, Oscar J.O.; Tavares, Maria I.B. [Universidade Federal do Rio de Janeiro (UFRJ), RJ (Brazil). Inst. de Macromoleculas Professora Eloisa Mano]. E-mail: oscarjop@ima.ufrj.br, mibt@ima.ufrj.br

    2005-07-01

    The copolymer content at least two monomer units that are the repetitive unities in the polymeric chains. The use of Low Field Nuclear Magnetic Resonance (LF-NMR), MARAN ultra 23, was applied to measure the proton spin-lattice relaxation time values. The process of copolymerization between the acrylic acid (A) and the styrene (S) monomers was studied with the addition of the octadecylamine (D) in the acrylic acid monomer. These materials were submitted at reflux by 24 hours. After this process the polymerization was carried out at room temperature. The values of the relaxation parameter are showed in Table 1. The co polymerizations between acrylic acid and styrene monomers were influenced by the octadecylamine addition. The results showed that an increase in the amine concentration promotes flexibility in the final material. This can be explained in terms of chains size after amine addition, which promotes an increasing in the free space among the polymer chains. (author)

  16. Application of stable isotopes to the NMR conformational study of peptides and membrane proteins; Application des isotopes stables a l`etude conformationnelle par RMN de peptides et proteines membranaires

    Energy Technology Data Exchange (ETDEWEB)

    Neumann, J.M.; Macquaire, F.; Cordier, F.; Musat, G.; Baleux, F. [CEA Centre d`Etudes de Saclay, 91 - Gif-sur-Yvette (France). Dept. de Biologie Cellulaire et Moleculaire; Huynh-Dinh, T.; Roux, M.; Sanson, A. [Centre National de la Recherche Scientifique (CNRS), 75 - Paris (France)

    1994-12-31

    The nuclear magnetic resonance spectral analysis of the lipid-peptide complexes generally necessitates isotopic enrichment, specifically or not, of the lipidic or peptidic partner. The isotope labelling depends on the membrane model and the associated NMR techniques: high resolution {sup 1}H NMR of peptides or proteins in the presence of per-deuterated phospholipidic micells, high resolution (micells) or ``solid`` type {sup 2}H NMR of the lipid partner, ``solid`` type NMR ({sup 15}N, {sup 13}C) of the peptide partner in a bi-layer. Application examples are given: utilization of stable isotopes for NMR study of lipopeptide structure and dynamic, of folding-up and functional linking at the annexines membrane interface, and of phospholipid conformation and dynamics in the lipids-ions-peptides interactions. 3 figs.

  17. Utilization of stable isotopes for studying biological macromolecules by high-resolution NMR; Utilisation des isotopes stables pour l`etude de macromolecules biologiques par R.M.N. a haute resolution

    Energy Technology Data Exchange (ETDEWEB)

    Jamin, N.; Gilles, N.; Lirsac, P.N.; Menez, A.; Toma, F. [CEA Centre d`Etudes de Saclay, 91 - Gif-sur-Yvette (France). Direction des Sciences du Vivant; Bostadt, A.; Gabrielsen, O.S. [Oslo Univ. (Norway)

    1994-12-31

    Stable isotope labelling applications for nuclear magnetic resonance study of proteins are reviewed and several examples of utilization of these techniques are given. Resolution limitations for very large protein are discussed. Examples are also given for labelling other biomolecules such as ARN and ADN with {sup 2}H, {sup 15}N and {sup 13}C (3D structure of proteins). 2 figs., 39 refs.

  18. Characterization of Maytenus ilicifolia samples by {sup 1}H NMR relaxation in the solid state; Caracterizacao dos constituintes polimericos da Maytenus ilicifolia por relaxacao nuclear de {sup 1}H por RMN no estado solido

    Energy Technology Data Exchange (ETDEWEB)

    Preto, Monica S. de M.; Tavares, Maria I.B., E-mail: mibt@ima.ufrj.br [Universidade Federal do Rio de Janeiro (IMA/UFRJ), RJ (Brazil). Inst. de Macromoleculas Professora Eloisa Mano. Lab de Ressonancia Magnetica Nuclear; Sebastiao, Pedro J.O. [Departamento de Fisica, Instituto Superior Tecnico, Lisboa (Portugal)

    2011-07-01

    The Maytenus ilicifolia (espinheira-santa) is a popular medicinal plant with different uses. It is native of South America and can be found in Brazil. In the Brazilian market it is possible found products labeled as M. ilicifolia. So far, the studies published in the literature involve the modification of the natural materials and do not concern the comparison between commercial the raw natural materials. Different non-destructive NMR techniques can be used to study natural materials. In this work it is presented a characterization study by Fast Field Cycling of the {sup 1}H spin-lattice relaxation time (T{sub 1}) NMR, in the frequency range 100 khz-10 MHz. The results obtained in two commercial M. ilicifolia samples and one control sample collected in natura are compared. It was intended to study the possibility to elaborate a characterization method using FFCNMR suitable for the verification of authenticity and/or evaluation of tampering on products. The differences detected by FFCNMR relaxometry were confirmed by thermogravimetric analysis and infrared spectroscopy. (author)

  19. Estudo da resposta metabólica de células de osteossarcoma a agentes anticancerígenos convencionais e novos por metabolómica de RMN

    OpenAIRE

    2015-01-01

    The main scope of this work was to evaluate the metabolic effects of anticancer agents (three conventional and one new) in osteosarcoma (OS) cells and osteoblasts, by measuring alterations in the metabolic profile of cells by nuclear magnetic resonance (NMR) spectroscopy metabolomics. Chapter 1 gives a theoretical framework of this work, beginning with the main metabolic characteristics that globally describe cancer as well as the families and mechanisms of action of drugs u...

  20. Phosphorus in chronosequence of burnt sugar cane in Brazilian cerrado: humic acid analysis by {sup 31}P NMR; Fosforo em cronossequencia de cana-de-acucar queimada no cerrado goiano: analise de acidos humicos por RMN de {sup 31}P

    Energy Technology Data Exchange (ETDEWEB)

    Rossi, Celeste Q.; Pereira, Marcos G.; Garcia, Andreas C., E-mail: mgervasiopereira@gmail.com [Universidade Federal Rural do Rio de Janeiro (UFRRJ), Seropedica, RJ (Brazil). Dept. de Solos; Perin, Adriano; Gazolla, Paulo R. [Instituto Federal de Educacao, Ciencia e Tecnologia Goiano, Rio Verde, GO (Brazil); Gonzalez, Antonio P. [Universidade de Coruna, ES (Spain). Faculdad de Ciencias

    2013-10-01

    The aim of this study was to identify, with the use of {sup 31}P NMR spectroscopy, organic P species in humic acids (HA) in samples from Oxisol cultivated in chronosequence with sugar cane, pasture and Cerrado. The main forms of P-type found were orthophosphate, monoester-P (phosphate sugars) and P-diester (orthophosphate). The {sup 31}P NMR technique proved capable of identifying changes in the areas studied as a function of sugar cane burning time. In areas with 1 and 5 years of burnt cane, a decrease in recalcitrant organic P in humic acids indicated the need for use of P-humic substances for plant nutrition (author)

  1. Etudes d'interactions moléculaires par RMN dans les systèmes complexes : utilisation de la technologie HR-MAS pour l'étude de l'interaction protéine ligand

    OpenAIRE

    Viéville, Justine

    2014-01-01

    NMR is a powerfull technique we decided to extend to follow interactions in complex mixtures. First part is about polydispersity index of polymer which is an important physical parameter when working with polymers. We developed here a new method, based on PEO analysis, using diffusion experiments (DOSY) by NMR to assess the polydispersity index: J. Viéville et al. / Journal of Magnetic Resonance 212 (2011) 169–173. In a second time, we worked on peptidic nucleic acids, PNA. These chemicals mo...

  2. Determinação estrutural de complexos Cd, Cu, Pb e Zn- DTPA: MS, Infravermelho, RMN13C e investigação teórica (DFT)

    OpenAIRE

    Silva, Vanézia Liane da

    2014-01-01

    Metais pesados, como: Pb, Cd, Zn e Cu, têm dificuldade de translocação nas plantas. O fenômeno parece estar ligado à facilidade de complexação com aminoácidos de plantas, produzindo estruturas estáveis com alto impedimento estérico. É conhecido que o ácido ietilenotriaminopentacético (DTPA) é um poliaminocarboxilato com estrutura semelhante a um aminoácido e que suas soluções já vêm sendo empregadas para determinar teores de elementos de transição no solo. Então este ligante foi escolhido com...

  3. étude du passage de l'état colloïdal à l'état ionique de solutions de silicates sodiques par spectrométries RMN 29Si et infrarouge

    Science.gov (United States)

    Couty, R.

    1998-02-01

    Silica sodic solutions with molar ratio Rms [ SiO2] /[ Na2O] of 4.56 to 1 were obtained by depolymerisation of amorphous silical gel in sodium hydroxide. Solutions have been characterized by Qn distribution and infrared spectra. The decrease in degree of polymerization of the silicate anions shifts the (1000 1100 cm-1) Si-O-Si frequencies to lower frequency. The solution colloid- ionic evolution occuring at Rms=2.27 is characterized by Q4 and 1075 cm-1 infrared band disappearance. Des solutions de silicate de sodium, dont les teneurs en silice étaient identiques mais dont les rapports (Rms) des concentrations molaires de SiO2 et de Na2O en solution étaient compris entre 4,56 et 1, ont été réalisées par dépolymérisation d'un gel de silice dans des solutions d'hydroxyde de sodium. Ces solutions ont été caractérisées par leurs distributions d'oligomères Qn et leurs spectres infrarouges. La dépolymérisation entraine une décroissance des fréquences de vibration des groupements (Si-O-Si) situées à (1000 1100 cm-1). Le passage de la solution de l'état colloïdal à l'état ionique, qui se fait pour un rapport Rms de 2,27 est caractérisé par la décroissance des Q3, la disparition des Q4 et de la composante infrarouge à 1075 cm-1.

  4. Palm oil based polymer materials obtained by ROMP: study by low field NMR; Materiais polimericos obtidos via ROMP a partir de oleo de palma: estudo por RMN de baixo campo

    Energy Technology Data Exchange (ETDEWEB)

    Fernandes, Henrique; Azevedo, Eduardo R. de; Lima-Neto, Benedito S., E-mail: benedito@iqsc.usp.br [Universidade de Sao Paulo (USP), Sao Carlos, SP (Brazil)

    2015-07-01

    Aiming to study and develop new materials synthesized from sustainable sources, several polymers were prepared using in its monomeric composition, different amounts of NPO (Norbornenyl Palm Oil) monomer. This monomer was developed based on a vegetable oil rather produced in northern Brazil, the Palm Oil. Since this oil have a low content of unsaturation, its use in developing new monomer for ROMP (Ring-Opening Metathesis Polymerization) is not exploited. In this regard, polymeric materials were obtained using the NOP and both the reaction process and the resulting products were analyzed by Nuclear Magnetic Resonance in the time domain (TD-NMR) at low magnetic field. (author)

  5. Study of relaxation times of nanocomposites of starch/montmorillonite employing low field NMR; Estudo dos tempos de relaxacao de nanocompositos de amido e argila montmorilonita por RMN de baixo campo

    Energy Technology Data Exchange (ETDEWEB)

    Brito, Luciana M.; Tavares, Maria Ines B. [Universidade Federal do Rio de Janeiro, Instituto de Macromoleculas Professora Eloisa Mano, Rio de Janeiro, RJ (Brazil)

    2011-07-01

    Due to its various applications and features, especially in therapies for controlled release of pharmaceuticals, polymers are among the most widely used excipients in pharmaceutical technology. One of the most promising nanocomposites is formed from organic polymer and inorganic clay minerals. Nanocomposites of starch/montmorillonite were prepared employing solution intercalation and characterized by proton spin-lattice relaxation time, through NMR relaxometry. The characterization of nanocomposites was done by X-ray diffraction and by nuclear magnetic resonance. The results showed that nanostructured films were obtained by intercalation from solution. Furthermore, the use of low field NMR, T1H, provided more precise information about the movement of materials, being complementary to the results obtained by X-ray diffraction. (author)

  6. Etude in situ par RMN HRMAS sur des épidermes reconstruits du métabolisme et de la réactivité de xénobiotiques allergisants

    OpenAIRE

    Moss, Éric

    2015-01-01

    Contact dermatitis is a skin pathology particularly prevalent in industrialized countries. No therapy currently exists and only complete avoidance of the particular allergen can prevent an allergic reaction. Historically, the assessment of skin sensitisation potential of molecules placed on the market was always carried out by animal testing. However, the scope of this testing method is now limited by the new European cosmetics legislation. In this way, the development of alternative methods,...

  7. Synthesis of poly(D,L-lactide-co-glycolide) copolymers and its chemical characterization by NMR and FTIR; Sintese e caracterizacao quimica por RMN e FTIR do copolimero poli(D,L-lactideo-co-glicolideo)

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2011-07-01

    Poly(D,L-lactide-co-glycolide) copolymer is of great interest for medical applications. This interest is justified by the fact that it is bioreabsorbable, biocompatible and non-toxic, while its degradation kinetics can be modified by the copolymerization ratio of the monomers. In this study, copolymers were synthesized at 175 deg C by opening the rings of the cyclic dimers of the D,L-lactide and glycolide monomers in the presence of stannous octoate initiator and lauryl alcohol co-initiator. The efficient application of a vacuum to the reaction medium, coupled with adequate stirring, is fundamental for the success of the synthesis. The following analysis techniques were used to characterize the synthesized copolymers: Nuclear Magnetic Resonance Spectroscopy (NMR) and Fourier Transform Infrared Spectroscopy (FTIR). The chemical composition and the ratio of the monomers in the synthesized copolymer were determined. (author)

  8. Screening protein-ligand interactions using {sup 1}H NMR techniques for detecting the ligand; Mapeamento das interacoes proteina-ligante atraves de tecnicas de RMN de {sup 1}H utilizando deteccao do ligante

    Energy Technology Data Exchange (ETDEWEB)

    Figueiredo, Isis Martins; Marsaioli, Anita Jocelyne [Universidade Estadual de Campinas (UNICAMP), SP (Brazil). Inst. de Quimica. Dept. de Quimica Organica]. E-mail: anita@iqm.unicamp.br

    2007-07-01

    NMR is a valuable screening tool for the binding of ligands to proteins providing structural information on both protein and ligands and is thus largely applied to drug-discovery. Among the recent NMR techniques to probe weak binding protein-ligand complexes we have critically evaluated the advantages and disadvantages of STD (Saturation Transfer Difference), WaterLOGSY (Water Ligand Observation with Gradient Spectroscopy), NOE pumping and DOSY-NOESY (Diffusion-Ordered NOESY) using a mixture of BSA (bovine serum albumin) plus salicylic acid, caffeine, citric acid, adipic acid and D-glucose. (author)

  9. Analysis of oil content and oil quality in oilseeds by low-field NMR; Analise do teor e da qualidade dos lipideos presentes em sementes de oleaginosas por RMN de baixo campo

    Energy Technology Data Exchange (ETDEWEB)

    Constantino, Andre F.; Lacerda Junior, Valdemar; Santos, Reginaldo B. dos; Greco, Sandro J.; Silva, Renzo C.; Neto, Alvaro C.; Barbosa, Lucio L.; Castro, Eustaquio V.R. de [Universidade Federal do Espirito Santo (UFES), Vitoria, ES (Brazil). Departamento de Quimica; Freitas, Jair C.C. [Universidade Federal do Espirito Santo (UFES), Vitoria, ES (Brazil). Departamento de Fisica

    2014-07-01

    To choose among the variety of oleaginous plants for biodiesel production, the oil content of several matrices was determined through different low-field {sup 1}H nuclear magnetic resonance (NMR) experiments with varied pulse sequences, namely single-pulse, spin-echo, CPMG, and CWFP. The experiments that involved the first three sequences showed high correlation with each other and with the solvent extraction method. The quality of the vegetable oils was also evaluated on the basis of the existing correlation between the T{sub 2} values of the oils and their properties, such as viscosity, iodine index, and cetane index. These analyses were performed using HCA and PCA chemometric tools. The results were sufficiently significant to allow separation of the oleaginous matrices according to their quality. Thus, the low-field {sup 1}H NMR technique was confirmed as an important tool to aid in the selection of oleaginous matrices for biodiesel production. (author)

  10. Validation of quantitative {sup 1}H NMR method for the analysis of pharmaceutical formulations; Validacao de metodo quantitativo por RMN de {sup 1}H para analises de formulacoes farmaceuticas

    Energy Technology Data Exchange (ETDEWEB)

    Santos, Maiara da S. [Universidade de Sao Paulo (USP), Sao Carlos, SP (Brazil). Instituto de Quimica; Colnago, Luiz Alberto, E-mail: luiz.colnago@embrapa.br [Embrapa Instrumentacao, Sao Carlos, SP (Brazil)

    2013-09-01

    The need for effective and reliable quality control in products from pharmaceutical industries renders the analyses of their active ingredients and constituents of great importance. This study presents the theoretical basis of Superscript-One H NMR for quantitative analyses and an example of the method validation according to Resolution RE N. 899 by the Brazilian National Health Surveillance Agency (ANVISA), in which the compound paracetamol was the active ingredient. All evaluated parameters (selectivity, linearity, accuracy, repeatability and robustness) showed satisfactory results. It was concluded that a single NMR measurement provides structural and quantitative information of active components and excipients in the sample. (author)

  11. Seed prepare for oil content determination by NMR method in six cotton varieties; Preparo de sementes para determinacao do teor de oleo pelo metodo de RMN em seis variedades de algodoeiro

    Energy Technology Data Exchange (ETDEWEB)

    Gondim-Tomaz, Rose Marry Araujo; Erismann, Norma de Magalhaes; Sabino, Nelson Paulieri; Kondo, Julio Isao; Cia, Edivaldo; Azzini, Anisio [Instituto Agronomico de Campinas, SP (Brazil). Centro de Algodao e Fibrosas Diversas]. E-mail: gondim@cec.iac.br; Soave, Daise [Instituto Agronomico de Campinas, SP (Brazil). Centro de Genetica, Biologia Molecular e Fitoquimica

    1998-07-01

    Three comparative methods (chemical seed-delinting with sulphuric acid solution, flaming and seed with linter) to prepare cotton seeds for oil determination by the Nuclear Magnetic Resonance (NMR) technique were considered. The chemical treatment with sulphuric acid was the best as long the linter interference was eliminated. The seed oil contents were determined by the NMR method in six cotton varieties from the national variety test. The IAPAR (Instituto Agronomico do Parana) 71 PR3 and IAC (Instituto Agronomico de Campinas) 20 varieties presented the highest oil content followed by the CNPA 7H, CS 50, IAC 22 and CNPA Precoce 2. (author)

  12. Characterization of Amazon fibers of the peach palm, balsa, and babassu by XDR, TGA and NMR; Caracterizacao das fibras amazonicas de pupunha, babacu e balsa atraves de DRX, TG e RMN

    Energy Technology Data Exchange (ETDEWEB)

    Martins, Maria A.; Marconcini, Jose M., E-mail: mariaalice@cnpdia.embrapa.br [Embrapa Instrumentacao, Sao Carlos-SP (Brazil); Morelli, Carolina L.; Marinelli, Alessandra L.; Bretas, Rosario E.S. [Universidade Federal de Sao Carlos - UFSCar, Sao Carlos, SP (Brazil)

    2011-07-01

    The aim of this work was to present the results by testing X-ray diffraction (XRD), thermogravimetric analysis (TG), nuclear magnetic resonance (NMR) and determining the moisture content of the peach palm, balsa and babassu fibers for assessing the feasibility of composite materials. The fibers of peach palm, balsa and babassu showed characteristic chemical structure of lignocellulosic material, and good thermal stability up to 220 deg C. The fiber with the highest crystallinity index (Ic) is the peach palm (72%) and the less crystalline is the babassu (37%), while the balsa fibers have Ic equal to 64%. The results have shown that these fibers can be used in the manufacture of composite materials. (author)

  13. {sup 1} H and {sup 13} C NMR studies on the enoling of 5-benzyl barbituric acids; Estudos por H-1 e C-13 RMN da enolizacao de acidos 5-benzil barbituricos

    Energy Technology Data Exchange (ETDEWEB)

    Villar, Jose Daniel Figueroa; Santos, Nedina Lucia dos; Cruz, Elizabete Rangel [Instituto Militar de Engenharia (IME), Rio de Janeiro, RJ (Brazil). Secao de Quimica

    1991-12-31

    This work shows that the derivatives of the 5-benzyl barbituric acids hydroxylated at the ortho position of the aromatic ring only exist in the enol form. and that the alkylation of this hydroxyl gives products which exist mainly in the ketone form of the DMSO 5 refs., 2 figs., 2 tabs.

  14. Comparative study of the formation of fenchenes and of their N.M.R. spectra; Etude comparative de la formation des fenchenes et de leurs spectres de R.M.N

    Energy Technology Data Exchange (ETDEWEB)

    Coulombeau, A. [Commissariat a l' Energie Atomique, Grenoble (France). Centre d' Etudes Nucleaires

    1970-01-01

    The dehydration of {alpha}-fenchyl alcohol and {alpha}-iso-fenchyl alcohol is studied in detail: two new techniques (chromatography on silica with silver nitrate, and nuclear magnetic resonance) permit to analyse the formation of various fenchenes and to achieve the synthesis of {alpha}- and {beta}-fenchenes. (author) [French] On etudie en detail la deshydratation de l'{alpha}-fenchol et de l'{alpha}-isofenchol: grace a l'utilisation de deux techniques nouvelles (chromatographie sur silice impregnee de nitrate d'argent et resonance magnetique nucleaire), on a pu analyser la formation des divers fenchenes. On met au point la preparation de l'{alpha}- et du {beta}-fenchenes. (auteur)

  15. Fractioning of sodium polyphosphate and characterization by {sup 31}P NMR: a experience to physical-chemistry lessons; Fracionamento de polifosfato de sodio e caracterizacao por RMN de 31P: um experimento para aulas de Fisico-Quimica

    Energy Technology Data Exchange (ETDEWEB)

    Lima, Emilia Celma de Oliveira; Alcantara, Glaucia Braz Alcantara; Damasceno, Fernando Cruvinel, E-mail: elima@quimica.ufg.b [Universidade Federal de Goias (UFG), Goiania, GO (Brazil). Inst. de Quimica; Moita Neto, Jose Machado [Universidade Federal do Piaui (UFPI), Teresina, PI (Brazil). Dept. de Quimica; Galembeck, Fernando [Universidade Estadual de Campinas (UNICAMP), SP (Brazil). Inst. de Quimica

    2010-07-01

    This text describes an experiment on fractional precipitation of a polymer together with determination of average degree of polymerization by NMR. Commercial sodium polyphosphate was fractionated by precipitation from aqueous solution by adding increasing amounts of acetone. The polydisperse salt and nine fractions obtained from it were analyzed by {sup 31}P nuclear magnetic resonance and the degree of polymerization of the salts and of the fractions were calculated. Long-chain sodium polyphosphate was also synthesized and analyzed. This experiment was tested in a PChem lab course but it can be used also to illustrate topics of inorganic polymers and analytical chemistry. (author)

  16. Determination of relative configurations and conformations of oxindole alkaloids from Uncaria guianensis by NMR; Determinacao por RMN das configuracoes relativas e conformacoes de alcaloides oxindolicos isolados de Uncaria guianensis

    Energy Technology Data Exchange (ETDEWEB)

    Carbonezi, Carlos Alberto; Hamerski, Lidilhone; Flausino Junior, Otavio Aparecido; Furlan, Maysa; Bolzani, Vanderlan da Silva [UNESP, Araraquara, SP (Brazil). Inst. de Quimica]. E-mail: bolzaniv@iq.unesp.br; Young, Maria Claudia Marx [Instituto de Botanica, Sao Paulo, SP (Brazil). Secao de Fisiologia e Bioquimica de Plantas

    2004-12-01

    Phytochemical studies with leaves of Uncaria guianensis resulted in the isolation of the oxindole alkaloids isomitraphylline (1), 3-isoajmalicine (2) mitraphylline (3), and isomitraphylinic acid (4). Structural assignments of these alkaloids, including relative configurations and conformations, were performed through spectral data and physical properties. 1D and 2D homonuclear and heteronuclear NMR spectroscopy was a valuable tool for the establishment of the relative stereochemistry of those compounds. (author)

  17. Determination of the percentage of quitine desacetilation reaction by solid state carbon-13 NMR; Determinacao do porcentual de reacao de desacetilacao de quitina por RMN {sup 13} C no estado solido

    Energy Technology Data Exchange (ETDEWEB)

    Ferracin, Ricardo J. [Sao Carlos Univ., SP (Brazil). Centro de Caracterizacao e Desenvolvimento; Cass, Quezia B.; Bassi, Ana L. [Sao Carlos Univ., SP (Brazil). Lab. de Sintese Organica

    1997-12-31

    Quitine is a bi-polymer largely found in invertebrates. As most compounds of this class are insoluble in common organic solvents, the des-acetylation percentile was obtained by carbon-13 solid state nuclear magnetic resonance. The methodology is presented. Results are presented 3 refs., 1 figs.

  18. γ-decay of {}_{8}^{16}{{\\rm{O}}}_{8}\\,{and}\\,{}_{7}^{16}{{\\rm{N}}}_{9} in proton-neutron Tamm-Dancoff and random phase approximations with optimized surface δ interaction

    Science.gov (United States)

    Pahlavani, M. R.; Firoozi, B.

    2016-09-01

    γ-ray transitions from excited states of {}16{{N}} and {}16{{O}} isomers that appear in the γ spectrum of the {}616{{{C}}}10\\to {}716{{{N}}}9\\to {}816{{{O}}}8 beta decay chain are investigated. The theoretical approach used in this research starts with a mean-field potential consisting of a phenomenological Woods-Saxon potential including spin-orbit and Coulomb terms (for protons) in order to obtain single-particle energies and wave functions for nucleons in a nucleus. A schematic residual surface delta interaction is then employed on the top of the mean field and is treated within the proton-neutron Tamm-Dancoff approximation (pnTDA) and the proton-neutron random phase approximation. The goal is to use an optimized surface delta interaction interaction, as a residual interaction, to improve the results. We have used artificial intelligence algorithms to establish a good agreement between theoretical and experimental energy spectra. The final results of the ‘optimized’ calculations are reasonable via this approach.

  19. {sup 1} H NMR spectral analysis bromine and iodine from o-xylene by simulation; Analise de espectros de RMN de {sup 1} H de bromo e iodo derivados de o-xileno por simulacao

    Energy Technology Data Exchange (ETDEWEB)

    Lopes, Julio C.D. [Minas Gerais Univ., Belo Horizonte, MG (Brazil). Dept. de Quimica; Arruda Campos, Ivan P. de; Rezende, Daisy de B.; Malta Junior, Jose S.; Alcantara, M. Regina [Sao Paulo Univ., SP (Brazil). Inst. de Quimica; Ebeling, Guenter [Rio Grande do Sul Univ., Porto Alegre, RS (Brazil). Inst. de Quimica

    1995-12-31

    The increasing interest on benzyl halides and related molecules for photochemistry is due to its flexibility as precursors. However, standard NMR data for this compounds haven`t been found in the literature. In order to supply this lack, this work has presented NMR data for some of them. {sup 1} H NMR spectra were analysed using a spectral simulation program, LAOCN9 program. The results were discussed widely 15 refs., 3 figs., 2 tabs.

  20. Study of the poly-aniline complexed with Li Cl O{sub 4} by Lithium-7 NMR; Estudo da polianilina complexada com Li Cl O{sub 4} por RMN do {sup 7} Li

    Energy Technology Data Exchange (ETDEWEB)

    Giotto, M.V.; Bonagamba, T.J.; Panepucci, H. [Sao Paulo Univ., Sao Carlos, SP (Brazil). Inst. de Fisica e Quimica; Mattoso, L.H.C.; Valenciano, G.R. [EMBRAPA, Sao Carlos, SP (Brazil). CNPDIA

    1997-12-31

    This work presents the chemical structure study of poly-aniline. The chemical preparation of the samples is presented. Also studied are the electric conductivity of the complexes of poly-aniline with Lithium. The samples were analysed by NMR. The spectra are presented 3 refs., 11 figs., 3 tabs.

  1. {sup 1}H-NMR characterization of cellulose acetate obtained from sugarcane bagasse; Caracterizacao de acetato de celulose obtido a partir do bagaco de cana-de-acucar por {sup 1}H-RMN

    Energy Technology Data Exchange (ETDEWEB)

    Cerqueira, Daniel A., E-mail: daniel.cerqueira@ufba.b [Universidade Federal da Bahia (UFBA), Salvador, BA (Brazil). Inst. de Ciencias Ambientais e Desenvolvimento Sustentavel; Rodrigues Filho, Guimes [Universidade Federal de Uberlandia (UFU), MG (Brazil). Inst. de Quimica; Carvalho, Rui de A. [Universidade de Coimbra (Portugal). Dept. de Bioquimica; Valente, Artur J.M. [Universidade de Coimbra (Portugal). Dept. de Quimica

    2010-07-01

    Cellulose from sugarcane bagasse was used for synthesizing cellulose acetate with different degrees of substitution, which were characterized by {sup 1}H-NMR through the relationship between the peak areas of the hydrogen atoms of the acetate groups (-(C=O)OCH{sub 3}) and the peaks of the hydrogen bonded to the carbon atoms of the glycosidic rings. Suppression of some signals was carried out in order to remove the residual water resonance in the materials and those related to impurities in cellulose triacetate as well. A deconvolution method for the computation of the degree of substitution of acetylation is proposed. The degrees of substitution for the cellulose samples were 2.94 and 2.60, in good agreement with those obtained by chemical determination through an acid-base titration. (author)

  2. Characterization of PHB, zinc oxide and organophilic clay nanocomposites with low field; Caracterizacao de nanocompositos de PHB com oxido de zinco e argila organofilica por RMN de baixo campo

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Mariana B.R.; Tavares, Maria Ines B.; Junior, Alberto W.M.; Neto, Roberto P.C. [Universidade Federal do Rio de Janeiro (UFRJ), Rio de Janeiro, RJ (Brazil)

    2013-07-01

    Nanoparticles of zinc oxide and organophilic clay (Viscogel B8) were added to PHB matrix in some different proportions. The nanocomposites containing both nanoparticles were obtained from solution casting method using chloroform as solvent. The films obtained were analyzed with X-ray diffraction and low field nuclear magnetic resonance to obtain answers about the interactions, dispersion and homogeneity of nanoparticles in the polymer matrix, just like the synergistic effects and the influence of them over some characteristics of the polymer. The synergistic effect achieved from the addition of both nanoparticles was also observed through hydrogen nuclear relaxation time values. (author)

  3. Transducer project and optimization of the ultra low magnetic field NMR tomograph reception system system; Projeto de transdutores e otimizacao do sistema de recepcao do tomografo de RMN de campo magnetico ultra baixo

    Energy Technology Data Exchange (ETDEWEB)

    Vidoto, Edson Luiz Gea

    1995-12-31

    The aim of the present work was to optimize the signal to noise ratio in our NMR imaging system (TORM 005) by improving transducer`s reception quality through better designed coils, balanced tuning circuit for this coils and power decoupling circuits and by reducing interference from the electromagnetic environment. For this purpose, we had to modify the internal electromagnetic shielding and incorporate line filters in the more critical signals paths. Also, new types of coils were developed, improving the signal to noise ratio, and allowing us to make clinical exams with superior quality for several anatomies. Balanced circuits for tuning and matching of the coil were studied and built, allowing a reduction of the coil losses because patient`s load. This produced a more reliable coil tuning after positioning each new patient. Circuits to avoid the receiver input overload and decoupling circuits for the isolation of receiver coils from excitation coil were designed and incorporated to the TORM 005. All these alterations of our imaging system (TORM 005) contributed to a significant improvement in the signal to noise ratio, reliability and reproducibility of the system. This permitted to operate the system routinely for clinical applications, research and development in the area of ultra low magnetic field tomography. (author) 46 refs., 66 figs., 11 tabs.

  4. Use of {sup 13} C NMR technique for establishing a spectral database of organic compounds; Aplicacion de la RMN {sup 13} C en el establecimiento de una base de datos espectral de compuestos organicos

    Energy Technology Data Exchange (ETDEWEB)

    Martinez, Jorge Alberto Garcia [Instituto Mexicano de Petroleo, Mexico City (Mexico); Hayamizu, Kikuko [National Institute of Materials and Chemical Investigation, Ibaraki (Japan). Div. of Basic Investigation

    1995-12-31

    A spectral database of organic compounds has been developed by Mexican Institute of Material and Chemical Research, in order to identify and characterize unknown substances. The database contains information about more than 25,000 compounds. This work has presented NMR spectra of several compounds which were used to implement this base and experimental data were also presented and an evaluation has been done 10 refs., 5 figs., 3 tabs.

  5. In vivo and high resolution spectroscopy in solids by NMR: an instrument for transgenic plants study; Espectroscopia `in vivo` e de alta resolucao em solidos por RMN: uma ferramenta para o estudo de plantas transgenicas

    Energy Technology Data Exchange (ETDEWEB)

    Colnago, L.A.; Herrmann, P.S.P.; Bernardes Filho, R. [EMBRAPA (Brazil). Centro Nacional de Pesquisa de Defesa da Agricultura; Bonagamba, T.J.; Panepucci, H. [Sao Paulo Univ., Sao Carlos, SP (Brazil). Inst. de Fisica; Carneiro, M.; Rodrigues, C.A. [EMBRAPA (CENARGEN) (Brazil)

    1995-12-31

    This work has developed a study on transgenic plants using two different techniques of nuclear magnetic resonance, in vivo NMR and high resolution NMR. In order to understand the gene mutations and characterize the plants constituents, NMR spectral data were analysed and discussed, then the results were presented 2 refs., 4 figs.

  6. Habitos alimentarios, morfometria y estados gonadales de cinco especies de peces en diferentes periodos climaticos en el Rio Sogamoso

    National Research Council Canada - National Science Library

    Ramirez C., Angelica; Pinilla A., Gabriel

    2012-01-01

    ... por la construccion y operacion de la represa Hidrosogamoso. Para cada ejemplar colectado se registraron la longitud estandar y el peso total, se calculo la relacion entre el peso y la longitud (P = a[L.sup.b...

  7. Aproximacion al Valor Economico Agregado (Economic Value Added, EVA) en organizaciones publicas

    National Research Council Canada - National Science Library

    Diaz Alvarez, Wilson Alberto

    2009-01-01

    ...]) en organizaciones del sector publico, en cuyo calculo y analisis se deben tener en cuenta las condiciones especificas de estas organizaciones, tales como la concepcion de valor publico, en la cual...

  8. La contabilidad vista como dispositivo de poder: aproximacion interpretativa desde la perspectiva foucaultiana

    National Research Council Canada - National Science Library

    Flor Ortega, Naila Katherine

    2013-01-01

    La contabilidad moderna, que se ha ido perfeccionando cada vez mas al incorporar, por ejemplo, practicas como el calculo de los costos y el control presupuestario, se ha convertido en una herramienta...

  9. Cannabinoid antagonist in nanostructured lipid carriers (NLCs): design, characterization and in vivo study.

    Science.gov (United States)

    Esposito, Elisabetta; Ravani, Laura; Drechsler, Markus; Mariani, Paolo; Contado, Catia; Ruokolainen, Janne; Ratano, Patrizia; Campolongo, Patrizia; Trezza, Viviana; Nastruzzi, Claudio; Cortesi, Rita

    2015-03-01

    This study describes the preparation, characterization, and in vivo evaluation in rats of nanostructured lipid carriers (NLCs) encapsulating rimonabant (RMN) as prototypical cannabinoid antagonist. A study was conducted in order to optimize NLC production by melt and ultrasonication method. NLCs were prepared by alternatively adding the lipid phase into the aqueous one (direct protocol) or the aqueous phase into the lipid one (reverse protocol). RMN-NLCs have been characterized by cryogenic transmission electron microscopy (cryo-TEM), X-ray, photon correlation spectroscopy (PCS) and sedimentation field flow fractionation (SdFFF). Reverse NLCs were treated with polysorbate 80. RMN release kinetics have been determined in vitro by dialysis method. In vivo RMN biodistribution in rats was evaluated after intranasal (i.n.) administration of reverse RMN-NLC. The reverse protocol enabled to prevent the lost of lipid phase and to achieve higher RMN encapsulation efficacy (EE) with respect to the direct protocol (98% w/w versus 67% w/w). The use of different protocols did not affect NLC morphology and dimensional distribution. An in vitro dissolutive release rate of RMN was calculated. The in vivo data indicate that i.n. administration of RMN by reverse NLC treated with polysorbate 80 increased RMN concentration in the brain with respect to the drug in solution. The nanoencapsulation protocol presented here appears as an optimal strategy to improve the low solubility of cannabinoid compounds in an aqueous system suitable for in vivo administration.

  10. TRANSOL- Tool of energetical calculation for solar thermal system based in dynamic simulations of real models; Transol- Herramienta de calculo energetico para sistemas solares termicos basada en simulaciones dinamicas de modelos reales simplicados

    Energy Technology Data Exchange (ETDEWEB)

    Salom, J.; Schweiger, H.; Gonzalez, D.; Gurruchaga, J.; Grau, J.

    2004-07-01

    In recent years, the implementation, in different cities of Spain, of Municipal Solar Ordinances, as well as the stimulus of the aids and subsidies from the different administrations, has caused a growing proliferation of the thermal solar systems. This expansion and diversification has not gone accompanied by a regulation and a more exhaustive methodology of calculation neither by new calculation tools that would permit to evaluate the behavior of this diversity of thermal systems. It is proposed a new tool, TRANSOL, a software of accessible calculation for the designer, any its technical qualification would be, based on dynamic simulations of simplified real models of the solar systems of greater currently applications. (Author)

  11. Evaluation of dose calculation algorithms using the treatment planning system XiO with tissue heterogeneity correction turned on; Validacao dos algoritmos de calculo de dose do sistema de planejamento XiO considerando as correcoes para heterogeneidade dos tecidos

    Energy Technology Data Exchange (ETDEWEB)

    Fairbanks, L.R.; Barbi, G.L.; Silva, W.T. da; Reis, E.G.F. dos; Borges, L.F.; Bertucci, E.C.; Maciel, M.F.; Amaral, L.L. do, E-mail: lefairbanks@yahoo.com.b [Universidade de Sao Paulo (USP), Ribeirao Preto, SP (Brazil). Hospital das Clinicas. Servico de Radioterapia

    2010-07-01

    Since the cross-section for various radiation interactions is dependent upon tissue material, the presence of heterogeneities affects the final dose delivered. This paper aims to analyze how different treatment planning algorithms (Fast Fourier Transform, Convolution, Superposition, Fast Superposition and Clarkson) work when heterogeneity corrections are used. To that end, a farmer-type ionization chamber was positioned reproducibly (during the time of CT as well as irradiation) inside several phantoms made of aluminum, bone, cork and solid water slabs. The percent difference between the dose measured and calculated by the various algorithms was less than 5%; This is in accordance with the recommendation of several references.The convolution method shows better results for high density materials (difference {approx}1 %), whereas the Superposition algorithm is more accurate for low densities (around 1,1%).

  12. Calculation of the electronic and magnetic structures of 3d impurities in the Hcp Fe matrix; Calculo da estrutura eletronica e magnetica de impurezas 3d na matriz do Fe HCP

    Energy Technology Data Exchange (ETDEWEB)

    Franca, Fernando

    1995-12-31

    In this work we investigate the local magnetic properties and the electronic structure of HCP Fe, as well introducing transition metals atoms 3d (Cs, Ti, Cr, Mn, Co, Ni, Cu, Zn) in HCP iron matrix. We employed the discrete variational method (DVM), which is an orbital molecular method which incorporate the Hartree-Fock-Slater theory and the linear combination of atomic orbitals (LCAO), in the self-consistent charge approximation and the local density approximation of Von Barth and Hedin to the exchange-correlation potential. We used the embedded cluster model to investigate the electronic structure and the local magnetic properties for the central atom of a cluster of 27 atoms immersed in the microcrystal representing the HCP Fe. (author) 32 refs., 19 figs., 2 tabs.

  13. Analysis of a calculation method for the determination of the value of safety or control bars; Analisis de un metodo de calculo para la determinacion del valor de barras de seguridad o control

    Energy Technology Data Exchange (ETDEWEB)

    Aguilar H, F.; Torres A, C.; Filio L, C. [ININ, Gcia. de Reactores, 52045 Ocoyoacac, Estado de Mexico (Mexico)

    1982-09-15

    Due to the control or safety bars in a nuclear reactor are constituted by strongly absorbent materials, the Diffusion Theory like tool for the calculation of bar values is not directly applicable, should it use the Transport Theory. However the speed and economy of the Diffusion codes for the reactors calculation, those make attractiveness and by this reason its are used in the determination of characteristic parameters and even in the determination of bar values, not without before to make some theoretical developments that allow to make applicable this theory. The application of the Diffusion Theory in strongly absorbent media is based on the use of some effective cross sections distinct from the real ones obtained when imposing the reason that among the flow and it gradient in the external surface of such media (control element in general, bar type or flagstone) be similar to the one obtained using Transport Theory in all the control region (multiplicative and absorbent media) with those real cross sections. The effective cross sections were obtained of the Leopard-NUMICE cell code which has incorporate the respective calculation theory of effective cross sections. Later these constants its were used in the bidimensional diffusion code Exterminator-II, simulating in it, the distribution of safety or control bars. From the cell code its were also obtained the respective constants of the homogeneous fuel cell. The results as soon as those obtained bar values of the diffusion code, its were compared with some experimental results obtained in the R{phi} Swedish reactor of natural uranium and heavy water. In this work an analysis of the bar value of one of them, trying to determine the applicability of the method is made. (Author)

  14. Thermical Load Calculation and Capacity of Cooling and Venting Equipment of a Diesel Engine Emissions Study Bench; Calculo de Cargas Termicas y Capacidad de los Equipos de Refrigeracion y Ventilacion de un Banco de Estudio de Emisiones de Motores Diesel

    Energy Technology Data Exchange (ETDEWEB)

    Rojas Garcia, E.; Fonseca Gonzalez, N. A.

    2005-07-01

    The present report tries to develop the calculation of thermical loads and to define the capacity of the equipments of cooling and ventilation that should have the engines test bench that is being ensemble in the installation of the CIEMAT named {sup D}iesel engine emissions study bench (E65-P0). The test bench is formed essentially by a dynamometrical brake and an engine connected at previous one, both of them inside a cabin of isolation acoustic. The thermical loads to be dissipated will be calculated for all the elements that compose the bench and considering his maximum values, to determine the suitable system of cooling air - water of the devices and ventilation in the cabin. (Author) 2 refs.

  15. Adjustment of algorithm of calculation Monte Carlo for Electrons (eMC) in the ECLIPSE Planer; Ajuste de algoritmo de calculo Monte Carlo para electrones (eMC) en el planificador Eclipse Planner

    Energy Technology Data Exchange (ETDEWEB)

    Verde Velasco, J. M.; Garcia Repiso, S.; Martin rincon, C.; Ramos Pacho, J. A.; Delgado Aparicio, J. M.; Perez alvarez, M. E.; Saez Beltran, M.; Gomez Gonzalez, N.; Cons Perez, N.; Sena Espinel, E.

    2013-07-01

    The implementation of a Monte Carlo algorithm requires not only a careful series of steps, but also adjust various parameters of calculation which will influence both in the goodness of the calculation of doses as in the time required for the calculation, being necessary to reach a compromise solution that get acceptable calculation accuracy in a time of calculation which is acceptable. In this paper we present our experience in this setting. (Author)

  16. Calculations of Changes in Reactivity during some regular periods of operation of JEN-1 MOD Reactor; Calculo de vairaciones de reactividad en algunos periodos regulares de operacion del reactor JEN-1 Mod.

    Energy Technology Data Exchange (ETDEWEB)

    Alcala Ruiz, F.

    1973-07-01

    By a Point-Reactor model and Perturbation Theory, changes in reactivity during some regular operating periods of JEN-1 MOD Reactor have been calculated and compared with available measured values. they were in good agreement. Also changes in reactivity have been calculated during operations at higher power levels than the present one, concluding some practical consequences for the case of increasing the present power of this reactor. (Author)

  17. Shield calculation of project for instrument calibration integrated laboratory of IPEN-Sao Paulo, Brazil; Calculo das blindagens do projeto de um laboratorio integrado de calibracao de instrumentos no IPEN - Sao Paulo, Brasil

    Energy Technology Data Exchange (ETDEWEB)

    Barros, Gustavo A.S.J.; Caldas, Linda V.E., E-mail: gustavaobarros@gmail.co, E-mail: lcaldas@ipen.b [Instituto de Pesquisas Energeticas e Nucleares (IPEN/CNEN-SP), Sao Paulo, SP (Brazil)

    2009-07-01

    This work performed the shield calculation of the future rooms walls of the five X-ray equipment of the Instrument Calibration Laboratory of the IPEN, Sao Paulo, Brazil, which will be constructed in project of laboratory enlargement. The obtained results by application of a calculation methodology from an international regulation have shown that the largest thickness of shielding (25.7 cm of concrete or 7.1 mm of lead) will be of the wall which will receive the primary beam of the equipment with a 320 kV voltage. The cost/benefit analysis indicated the concrete as the best material option for the shielding

  18. Dose calculation for {sup 40}K ingestion in samples of beans using spectrometry and MCNP; Calculo de dose devido a ingestao de {sup 40}K em amostras de feijao utilizando espectrometria e MCNP

    Energy Technology Data Exchange (ETDEWEB)

    Garcez, R.W.D.; Lopes, J.M.; Silva, A.X., E-mail: marqueslopez@yahoo.com.br [Coordenacao dos Programas de Pos-Graduacao em Engenharia (COPPE/PEN/UFRJ), Rio de Janeiro, RJ (Brazil). Centro de Tecnologia; Domingues, A.M. [Universidade Federal Fluminense (UFF), Niteroi, RJ (Brazil). Instituto de Fisica; Lima, M.A.F. [Universidade Federal Fluminense (UFF), Niteroi, RJ (Brazil). Instituto de Biologia

    2014-07-01

    A method based on gamma spectroscopy and on the use of voxel phantoms to calculate dose due to ingestion of {sup 40}K contained in bean samples are presented in this work. To quantify the activity of radionuclide, HPGe detector was used and the data entered in the input file of MCNP code. The highest value of equivalent dose was 7.83 μSv.y{sup -1} in the stomach for white beans, whose activity 452.4 Bq.Kg{sup -1} was the highest of the five analyzed. The tool proved to be appropriate when you want to calculate the dose in organs due to ingestion of food. (author)

  19. Calculation of cooling internal circuits loss of load curve in giant electric machines; Calculo da curva de perda de carga dos circuitos axiais internos de refrigeracao de maquinas eletricas gigantes

    Energy Technology Data Exchange (ETDEWEB)

    Silva, Hilton Penha [Parana Univ., Curitiba, PR (Brazil). Dept. de Engenharia Mecanica. Dept. de Engenharia do Produto; Passos, Alex Sandro Barbosa [Parana Univ., Curitiba, PR (Brazil). Dept. de Engenharia Mecanica. Dept. de Pesquisa e Desenvolvimento do Produto

    2001-07-01

    This article describes a method for calculation of the loss of load curve for the ventilation axial circuits. The method assumes the ventilation circuit representation in a way similar to the electrical circuits. The great difficulty of circuit solution resides in the non linearity of the loss of load resistances and the equations relating the pressures and flows. The method is based on the association of the resistance curves of loss of load in a such way that, when the resistance curve of the total circuit loss of load is obtained, the blower operation point can be easily obtained and, consequently, the individual flows for each section of the circuit.

  20. Methodology for calculating the thickness free of sigma phase in duplex stainless steels large section parts during hiperquenching; Metodologia para el calculo de espesores limite libres de fase sigma durante el hipertemple en piezas de aceros duplex de gran seccion

    Energy Technology Data Exchange (ETDEWEB)

    Jimbert, P.; Guraya, T.; Torregary, A.; Bravo, P.

    2013-06-01

    To achieve the mechanical properties and corrosion resistance desired by duplex stainless steels used by the petrochemical and nuclear industry, parts are subjected to a hiperquenching heat treatment from about 1050 degree centigrade. This avoids the risk of intermetallic precipitation which drastically reduces the properties of these materials. However with increasing depth to which the deposits are present, the thicknesses for such pipes have been increased, resulting in higher levels of demand on all its manufacturing process, including the heat treatment. To avoid the precipitation of intermetallic phases such as sigma phase it is necessary to know the cooling profile in the center of the work piece and for this purpose to know the value of the Surface Heat Transfer Coefficient (h) is essential. This coefficient changes during the hiperquenching and its value is determined experimentally as it depends on several process parameters. Studies reveal that its value is stabilized within a few seconds. We can then assume that to know the cooling profile in the center of large sections it is only necessary to know the stabilized value of h. However, all the studies found in the literature are referred to diameters smaller than 100 mm. This paper has developed a methodology to predict the precipitation of intermetallic phases in duplex stainless steel parts with large thicknesses in industrial facilities from the calculation of h. This methodology allows us to calculate the cooling profiles without wasting any work piece using one or more sensorized patterns with thermocouples and a subsequent simulation with ANSYS. (Author)

  1. Verification of dosimetry planning in brachytherapy in format Dicom and EUD calculation of Risk in bodies; Verificacion de la planificacion dosimetria en braquiterapia en formato Dicom y calculo del EUD en organos de riesgo

    Energy Technology Data Exchange (ETDEWEB)

    Garcia Hernandez, M. J.; Sendon del Rio, J. R.; Ayala Lazaro, R.; Jimenez Rojas, M. R.; Gomez Cores, S.; Polo Cezon, R.; Lopez Bote, M. A.

    2013-07-01

    This work Describes a program that automates the verification of the schedules in brachytherapy (configuration and dosimetric treatment parameters) for sources of Ir-192 (mHDR v2) and Co-60 (Co0.A86) from the plan exported in DICOM format data. (Author)

  2. Dancoff factors with partial neutrons absorption in cluster geometry by the direct method; Calculo dos fatores de Dancoff com absorcao parcial de neutrons em geometria cluster pelo metodo direto

    Energy Technology Data Exchange (ETDEWEB)

    Rodrigues, Leticia Jenisch

    2007-07-01

    Accurate analysis of resonance absorption in heterogeneous systems is essential in problems like criticality, breeding ratios and fuel depletion calculations. In compact arrays of fuel rods, resonance absorption is strongly affected by the Dancoff factor, defined in mis study as the probability that a neutron emitted from the surface of a fuel element, enters another fuel element without any collusion in the moderator or cladding. In fact, in the most practical cases of irregular cells, it is observed that inaccuracies in computing both Grey and Black Dancoff factors, i.e. for partially and perfectly absorbing fuel rods, can lead to considerable errors in the calculated values of such integral quantities. For this reason, much effort has been made in the past decades to further improve the models for calculating Dancoff factors, a task that has been accomplished in connection with the development of faster computers. In the WIMS code, Black Dancoff factors based on the above mentioned collusion probability definition are computed in cluster geometry, for each one of the symmetrically distinct fuel pin positions in the cell. Sets of equally-spaced parallel lines are drawn in subroutine PIJ, at a number of discrete equally-incremented azimuthal angles, covering the whole system and forming a mesh over which the in-plane integrations of the Bickley functions are carried out by simple trapezoidal rule, leading to the first-flight collusion matrices. Although fast, the method in PIJ is inefficient, since the constructed mesh does not depended on the system details, so that regions of small relative volumes are crossed out by relatively few lines, which affects the convergence of the calculated probabilities. A new routine (PIJM) was then created to incorporate a more efficient integration scheme considering each system region individually, minimizing convergence problems and reducing the number of neutron track lines required in the in-plane integrations for any given accuracy. In this routine, the radial integrations are performed by Gauss' formula whereas the angular ones are obtained by extended trapezoidal rule. In the present work, PIJM is extended to compute Grey Dancoff factors by the collision probability definition, in two-dimensional cylindrical cells in cluster geometry. The vi effectiveness of the method is accessed by comparing Grey Dancoff factors as calculated by PIJM, with those available in the literature by the Monte Carlo method, for the irregular geometries of the Canadian CANDU 37 assembly. Dancoff factors at five symmetrically distinct fuel pin positions are found in very good agreement with the literature results. (author)

  3. Evaluation of dose calculation algorithms using the treatment planning system Xi O with tissue heterogeneity correction turned on; Validacao dos algoritmos de calculo de dose do sistema de planejamento Xi O considerando as correcoes para heterogeneidade dos tecidos

    Energy Technology Data Exchange (ETDEWEB)

    Fairbanks, Leandro R.; Barbi, Gustavo L.; Silva, Wiliam T.; Reis, Eduardo G.F.; Borges, Leandro F.; Bertucci, Edenyse C.; Maciel, Marina F.; Amaral, Leonardo L., E-mail: lefairbanks@yahoo.com.b [Universidade de Sao Paulo (HCRP/USP), Ribeirao Preto, SP (Brazil). Hospital das Clinicas. Servico de Radioterapia

    2011-07-01

    Since the cross-section for various radiation interactions is dependent upon tissue material, the presence of heterogeneities affects the final dose delivered. This paper aims to analyze how different treatment planning algorithms (Fast Fourier Transform, Convolution, Superposition, Fast Superposition and Clarkson) work when heterogeneity corrections are used. To that end, a farmer-type ionization chamber was positioned reproducibly (during the time of CT as well as irradiation) inside several phantoms made of aluminum, bone, cork and solid water slabs. The percent difference between the dose measured and calculated by the various algorithms was less than 5%.The convolution method shows better results for high density materials (difference {approx}1 %), whereas the Superposition algorithm is more accurate for low densities (around 1,1%). (author)

  4. Calculation of the convective heat transfer coefficient incorporating the intra particle effect in heat regenerators; Calculo do coeficiente de transferencia de calor convectivo incorporando o efeito intraparticula em regeneradores de calor

    Energy Technology Data Exchange (ETDEWEB)

    Hasan, Wajdi M.; Andrade, Alberto L. de [Universidade Estadual de Campinas, SP (Brazil). Faculdade de Engenharia Quimica. Dept. de Engenharia de Processos Quimicos

    1995-07-01

    This work presents a methodology for the determination of the convective heat transfer coefficient in fixed bed heat regenerators, making use of intraparticle model. An experimental equipment has been utilized, providing a set of experimental data with three different diameters, all of them composed by a bed of spherical glass particles. Correlations in the form j{sub h}{theta}=aRe{sub m}{sup b} were obtained for counter and parallel flow. (author)

  5. Study of the workload to be applied in the shielding calculation in HDR brachytherapy facilities with IR-192; Estudio de la carga de trabajo a aplicar en el calculo de blindajes en instalaciones de braquiterapia HDR con IR-192

    Energy Technology Data Exchange (ETDEWEB)

    Pujades-Clamarchirant, M. C.; Perez-Calatayud, J.; Ballester, F.; Gimeno, J.; Granero, D.; Camacho, C.; Carmona, V.; Lliso, F.; Vijande, J.

    2011-07-01

    The design of shielding facilities high rate brachytherapy (HDR) requires an estimate of the workload (w) . The aim of this study was to evaluate the W typical service HDR BT with a high number of applications and their impact on the final thickness the shielding of the room. To do this, a review of patients treated in our center HDR W has been evaluated and studied their impact on the shielding design of the facility.

  6. Determination of viscosity of fayalite slags for kv model and measurements by means of inclined plane; Estimacion de la viscosidad de escorias fayaliticas utilizando el modelo de calculo kv y el metodo experimental del plano inclinado

    Energy Technology Data Exchange (ETDEWEB)

    Bazan, V.; Goni, C.; Castella, L.; Brandaleze, E.; Verdeja, L. F.; Parra, R.

    2006-07-01

    The viscosity of the lands represents one of the most relevant variables of most of the processes metallurgical and kinetics of the refine operations, since it is one of the decisive factors of the efficiency in the reactions between metal and lag, as much as slag-refractory. In the last decades, the mathematical models of different metallurgical processes have established methods to predict viscosity of mixtures of oxides fused to high temperatures in function of the chemical composition. The model developed by Toguri, based on the data reported by Johasen and Winterhager et al has proposed the Kv model. The used index it is similar to the relationship used in the steel industry like the basicity index. It is presented in this work values determined of viscosity in experimental form by means of the technique of inclined plane. (Author)

  7. Hydrodynamic calculation of a filter sand bed type used in the containment venting systems; Calculo hidrodinamico de un filtro tipo lecho de arena usado en los sistemas de venteo de la contencion

    Energy Technology Data Exchange (ETDEWEB)

    Cuevas V, D.; Sainz M, E.; Ortiz V, J., E-mail: delfy.cu@gmail.com [ININ, Carretera Mexico-Toluca s/n, 52750 Ocoyoacac, Estado de Mexico (Mexico)

    2015-09-15

    The filtered venting of the containment has been adopted in European countries to mitigate the consequences of excess pressure containment during a severe accident. When venting has taken place, the fission products are released directly into the environment, unless a filter on the same path is placed, so that various types of filters are used to trap the fission products. The venting filters of the containment currently installed use different filtration technologies that involve more than one medium. Those using water as the first stage of filtration are called wet systems and are equipped with additional steps to remove water drops and fine aerosols emissions. And even they may also be equipped with an element containing certain absorption means for the filtration of gaseous iodine species. Other designs based on filtration of deep bed as the primary retention step; called dry filters, use filtration media of metal fiber, ceramic or sand to trap aerosols. This paper evaluates the hydraulic characteristics of the filter sand bed type designed by EDF as a candidate to be installed in the containment of BWR Mark II (type of primary containment of the nuclear power plant of Laguna Verde). The evaluation of filter sand bed type was performed using the software package of open source OpenFOAM. Models of each zone of the filtered device were generated and through a series of parametric calculations of computational fluid mechanics relevant hydrodynamic characteristics of the device were obtained, such as pressure drops against mass flow rate and pressure fields and speed at different operating conditions. On the other hand, the model validation of the sand bed filter when comparing the results of experimental tests on a sand column of PITEAS program (1985-1986) against OpenFOAM simulation was realized. The results are very close to those obtained experimentally. (Author)

  8. Hydrodynamic calculation of a filter washing in liquids type used in containment venting systems; Calculo hidrodinamico de un filtro tipo lavado en liquidos usados en los sistemas de venteo de la contencion

    Energy Technology Data Exchange (ETDEWEB)

    Reyes G, A. A.; Sainz M, E.; Ortiz V, J., E-mail: alejandroantonioreyess@gmail.com [ININ, Carretera Mexico-Toluca s/n, 52750 Ocoyoacac, Estado de Mexico (Mexico)

    2015-09-15

    From the nuclear accident of Chernobyl, the European nuclear power plants have chosen to install filters on the venting pipes of the containment, whose function is to help to mitigate the consequences of a severe accident, by controlled depressurization of the containment passively through a filtered venting of the containment system. These systems are designed to relieve the internal pressure of the containment by means of the deliberate opening of pressure relief devices, either a valve or rupture disc during a severe accident and be channeled to the filter unit. In this paper the hydraulic response of a filter system of gases washing by liquid is evaluated, due to this information is necessary to estimate the effect that has the pressure increase of the contention on the discharge capacity of the venting pipes. By simulation of computational of fluid dynamics with the programs: CAELINUX-2014 and OpenFOAM, the hydrodynamic characteristics of the Multi Venturi System for gases washing from the containment, which could be included in the general model of the venting pipe, were obtained. Representative models of the Venturi tubes of each concentric area that forming the washing system were generated; and using parametric calculations the average mass flow rate established through each venturi, depending on its size and depth in which it is located inside the tank was estimated. Also, the pressure and mass flow rate required to activate each concentric area depending on the pressure and mass load from the containment were calculated, to estimate the maximum flow that is established through the filter. Finally, the velocity profiles and the characteristic pressure at which each area operates as well as the pressure drop of local and global discharge also were calculated. (Author)

  9. Calculation of the detection efficiency in liquid scintillators. II. Single positron emitters; Calculo de la eficiencia de deteccion en liquidos centelleadores. II Nucleidos que se desintegran por emision simple de positrones

    Energy Technology Data Exchange (ETDEWEB)

    Grau Malonda, A.; Garcia Torano, E.

    1982-07-01

    Counting efficiency as a function of the figure of merit for 30 positron emitters has been computed from the positron energy spectrum. Only the efficiency contribution of positrons has been taken into consideration. The contribution of the annihilation photons depending on the volume of the scintillator will be investigated in a near future. Efficiency vs figure of merit is plotted and tabulated. (Author) 19 refs.

  10. Aquelarre. A computer code for fast neutron cross sections from the statistical model; AQUELARRE. Un programa numerico para el calculo de secciones eficaces neutronicas mediante el modelo de nucleo compuesto

    Energy Technology Data Exchange (ETDEWEB)

    Guasp, J.

    1974-07-01

    A Fortran V computer code for Univac 1108/6 using the partial statistical (or compound nucleus) model is described. The code calculates fast neutron cross sections for the (n, n'), (n, p), (n, d) and (n, {alpha}) reactions and the angular distributions and Legendre moments for the (n, n) and (n, n') processes in heavy and intermediate spherical nuclei. A local Optical Model with spin-orbit interaction for each level is employed, allowing for the width fluctuation and Moldauer corrections, as well as the inclusion of discrete and continuous levels. (Author) 67 refs.

  11. Calculation of Departure from Nucleate Boiling Ratio (DNBR) minimum for accident analysis of main steam line break at Angra-1; Calculo do minimo DNBR para analise do acidente de ruptura da linha principal de vapor em Angra-1

    Energy Technology Data Exchange (ETDEWEB)

    Machado, Marcio Dornellas [ELETROBRAS Termonuclear S.A. (ELETRONUCLEAR), Rio de Janeiro, RJ (Brazil). E-mail: mdorne@eletronuclear.gov.br

    2000-07-01

    The maintenance costs, the operational problems and the failures possibilities of the boron injection system, composed by pumps, valves, heated lines and the boron injection tank, make this tank removal or the boron concentration reduction advisable for Angra 1 Power Plant. The main accident from chapter XV of the final safety analysis report affected by this modification is the main steam line break. It is necessary the interaction of the areas of Accidents and Transients Analysis (RETRAN 02/Mod 5.1 code), Neutronics (APA System) and Thermohydraulics (COBRA IIIC/MIT) to analyse this accident. The present Angra 1 boron concentration is 20000 ppm and it could be reduced to 2000 ppm as a result of the present study. The Departure from Nucleate Boiling Ratio (DNBR) is the restrictive parameter of this accident, which is calculated from the initials and boundary conditions obtained from the Transients and Accidents Analysis and Neutronics areas. (author)

  12. Validation of WIMS-SNAP code systems for calculations in TRIGA-MARK II type reactors; Validacion del sistema de codigos WIMS-SNAP para calculos en reactores nucleares tipo TRIGA-MARK II

    Energy Technology Data Exchange (ETDEWEB)

    Hernandez Valle, S.; Lopez Aldama, D. [Centro de Investigaciones Nucleares, Tecnologicas y Ambientales, La Habana (Cuba). E-mail: svalle@ctn.isctn.edu.cu

    2000-07-01

    The following paper contributes to validate the Nuclear Engineering Department methods to carry out calculations in TRIGA reactors solving a Benchmark. The benchmark is analyzed with the WIMS-D/4-SNAP/3D code system and using the cross section library WIMS-TRIGA. A brief description of the DSN method is presented used in WIMS/d{sup 4} code and also the SNAP-3d code is shortly explained. The results are presented and compared with the experimental values. In other hand the possible error sources are analyzed. (author)

  13. A computational model for reliability calculation of steam generators from defects in its tubes; Um modelo computacional para o calculo da confiabilidade de geradores de vapor a partir de defeitos em seus tubos

    Energy Technology Data Exchange (ETDEWEB)

    Rivero, Paulo C.M.; Melo, P.F. Frutuoso e [Universidade Federal, Rio de Janeiro, RJ (Brazil). Coordenacao dos Programas de Pos-graduacao de Engenharia. Programa de Engenharia Nuclear

    2000-07-01

    Nowadays, probability approaches are employed for calculating the reliability of steam generators as a function of defects in their tubes without any deterministic association with warranty assurance. Unfortunately, probability models produce large failure values, as opposed to the recommendation of the U.S. Code of Federal Regulations, that is, failure probabilities must be as small as possible In this paper, we propose the association of the deterministic methodology with the probabilistic one. At first, the failure probability evaluation of steam generators follows a probabilistic methodology: to find the failure probability, critical cracks - obtained from Monte Carlo simulations - are limited to have length's in the interval defined by their lower value and the plugging limit one, so as to obtain a failure probability of at most 1%. The distribution employed for modeling the observed (measured) cracks considers the same interval. Any length outside the mentioned interval is not considered for the probability evaluation: it is approached by the deterministic model. The deterministic approach is to plug the tube when any anomalous crack is detected in it. Such a crack is an observed one placed in the third region on the plot of the logarithmic time derivative of crack lengths versus the mode I stress intensity factor, while for normal cracks the plugging of tubes occurs in the second region of that plot - if they are dangerous, of course, considering their random evolution. A methodology for identifying anomalous cracks is also presented. (author)

  14. Calculation of dose distribution in the patient for verification of plans of intensity modulated radiation therapy; Calculo de la distribucion de dosis en el paciente para la verificacion de planes de radioterapia de intensidad modulada

    Energy Technology Data Exchange (ETDEWEB)

    Perez Moreno, J. M.; Zucca Aparicio, D.; Garcia Ruiz-Zorrila, J.; Fernandez Leton, J. P.; Minambres Moro, A.

    2013-07-01

    The precision in the delivery of radiation therapy treatments intensity modulated depends on, among other things, of the proper administration of the sequence of radiation calculated on the planning system. In recent years the electronic devices of imaging portal have shown as a useful tool for the measurement of dose distribution with high resolution. An algorithm has been developed to calculate the distribution of dose in the patient's Anatomy, using the accelerator as measuring equipment electronic imaging of portal In this way the acceptance criteria can be changed in the dosimetry verifications pretreatment of radiation therapy treatments, from those based on evaluation of gamma index to others based on the evaluation of the distribution of dose in the patient. (Author)

  15. REPERCUSION DEL USO DE LA PLATAFORMA VIRTUAL MATHXL EN EL RENDIMIENTO ACADEMICO DE LOS ALUMNOS EN EL CURSO CALCULO INTEGRAL DEL PROGRAMA PROFESIONAL INGENIERIA CIVIL DE LA UNIVERSIDAD CATOLICA DE SANTA MARIA DE AREQUIPA 2010-II Y 2011-II

    OpenAIRE

    SÁNCHEZ-MORENO MESTAS, MARTHA BEATRIZ

    2013-01-01

    EL APRENDIZAJE DEFINICIONES TIPOS DE APRENDIZAJE APRENDIZAJE POR ENSAYO Y ERROR TEORÍAS DEL APRENDIZAJE LAS ESTRATEGIAS DE APRENDIZAJE EL MODELO DE ENSEÑANZA-APRENDIZAJE EN LA UNIVERSIDAD LA ENSEÑANZA-APRENDIZAJE Y LOS ENTORNOS VIRTUALES EL AULA VIRTUAL DEFINICIÓN DE AULA VIRTUAL USOS DEL AULA VIRTUAL LA ENSEÑANZA VIRTUAL UNIVERSITARIA AMBIENTES HÍBRIDOS DE APRENDIZAJE PLATAFORMAS VIRTUALES DE APRENDIZAJE USO DE LAS PLATAFORMAS DE ENSEÑANZA VIRTUAL EN LA DOCENCIA UNIVERSITARIA VENTAJAS QUE LA...

  16. Calculation of dose due to exposure internal in the services of nuclear medicine of Peru; Calculo de dosis debida a la exposicion interna en los servicios de medicina nuclear del Peru

    Energy Technology Data Exchange (ETDEWEB)

    Gonzalez, S.; Zapata, L.; Cardenas, A.; Velasquez, M.

    2013-07-01

    The objective of this work is to improve the radiation protection of workers occupationally exposed to open source of nuclear medicine services and train those responsible for radiation protection of such installations to carry a comprehensive record of doses. (Author)

  17. Comparative study between NCRP-49 and NCRP-147 methodologies for shielding calculus to fluoroscopy rooms; Estudo comparativo entre as metodologias da NCRP-49 e da NCRP-147 para calculo de blindagem para salas de fluoroscopia

    Energy Technology Data Exchange (ETDEWEB)

    Ferreira, Christiano Eduardo Martins

    2011-07-01

    The walls of a fluoroscopy room must be shielded to prevent unnecessary exposures to technicians and public individuals. Thus this dissertation aims to describe the methodologies contained in two documents which are references for the calculation of shielding those rooms. They are the National Council on Radiation Protection and Measurements Report No. 49 (NCRP Report No. 49) and No. 147 (NCRP Report No. 147), the latter being more recent publication. And based on such description was made a comparative study between the two methodologies, using for this, as a benchmark, spreadsheets computer program developed by Wolfram Mathematica 6. With that we could reach the final thickness of the barriers to a Standard Plan for a fluoroscopy room (provided by Siemens) and noted that the NCRP-49 presents a methodology with results more conservative. (author)

  18. Evolution calculations of fuel for a GFR using MCNPX-C90 and Tripoli-4-D; Calculos de evolucion de combustible para un GFR usando MCNPX-C90 y TRIPOLI-4-D

    Energy Technology Data Exchange (ETDEWEB)

    Reyes R, R.; Martin del Campo M, C.; Francois L, J. L. [UNAM, Facultad de Ingenieria, Departamento de Sistemas Energeticos, Paseo Cuauhnahuac 8532, 62550 Jiutepec, Morelos (Mexico); Brun, E.; Dumonteil, E.; Malvagi, F., E-mail: emeric.brun@cea.fr [Commissariat a l' Energie Atomique et aux Energies Alternative, Service d' Etude des Reacteurs et de Mathematiques Appliquees, Saclay, DEN/DM2S/SERMA/LTSD, Bat 470, 91191 Gif-sur-Yvette Cedex (France)

    2011-11-15

    Burnt calculations were realized for a fuel model based on the technology of the Gas-cooled Fast Reactor, GFR. The fuel design is based on bars. The code MCNPX-CINDER90 and the CSADA method for the burnt calculations were used. Models of homogeneous and heterogeneous fuel assembly were studied; for the burnt calculations of the fuel homogeneous model was considered the tracking of three series (Tiers) of evolution of the fission products. The Tier 1 tracks a reduced group of fission products, the Tier 2 tracks to the arrangement of fission products that are contained in the library of cross sections XSDIR of MCNPX; and the Tier 3 tracks 1325 fission products. The results were compared with those obtained with Tripoli-4-D in function of the calculation methods: 1) Explicit Euler, as method of first order; and 2) CSADA, as method of second order. According to the results was observed that the infinite multiplication factor varies in function of the fission products quantity that are tracked. The calculation time used by MCNPX-C90 with the series Tier 3 is more than double than the used by Tripoli-4-D, therefore this last code has advantage over MCNPX-C90 in the case of neutrons analysis of fast reactors. (Author)

  19. A combination of differential method and perturbation theory for the calculation of sensitivity coefficients; Uma combinacao entre os metodos diferencial e da teoria de perturbacao para o calculo dos coeficientes de sensibilidade

    Energy Technology Data Exchange (ETDEWEB)

    Santos, Adimir dos [Instituto de Pesquisas Energeticas e Nucleares (IPEN), Sao Paulo, SP (Brazil); Borges, A.A. [Centro Tecnico Aeroespacial (CTA-IEAv), Sao Jose dos Campos, SP (Brazil). Inst. de Estudos Avancados

    2000-07-01

    A new method for the calculation of sensitivity coefficients is developed. The new method is a combination of two methodologies used for calculating these coefficients, which are the differential and the generalized perturbation theory methods. The proposed method utilizes as integral parameter the average flux in an arbitrary region of the system. Thus, the sensitivity coefficient contains only the component corresponding to the neutron flux. To obtain the new sensitivity coefficient, the derivates of the integral parameter, {phi}({xi}), with respect to {sigma} are calculated using the perturbation method and the functional derivates of this generic integral parameter with respect to {sigma} and {phi} are calculated using the differential method. The new method merges the advantages of the differential and generalized perturbation theory methods and eliminates their disadvantages. (author)

  20. Coordinated Use of Heterogeneous Infrastructures for Scientific Computing at CIEMAT by means of Grid Technologies; Aprovechamiento Coordinado de las Infraestructuras Heterogeneas para Calculo Cientifico Participadas por el CIEMAT por medio de Tecnologias Grid

    Energy Technology Data Exchange (ETDEWEB)

    Rubio-Montero, A. J.

    2008-08-06

    Usually, research data centres maintain platforms from a wide range of architectures to cover the computational needs of their scientists. These centres are also frequently involved in diverse national and international Grid projects. Besides, it is very difficult to achieve a complete and efficient utilization of these recourses, due to the heterogeneity in their hardware and software configurations and their unequal use along the time. This report offers a solution to the problem of enabling a simultaneous and coordinated access to the variety of computing infrastructures and platforms available in great Research Organisms such as CIEMAT. For this purpose, new Grid technologies have been deployed in order to facilitate a common interface which enables the final user to access the internal and external resources. The previous computing infrastructure has not been modified and the independence on its administration has been guaranteed. For a sake of comparison, a feasibility study has been performed with the execution of the Drift Kinetic Equation solver (Dikes) tool, a high throughput scientific application used in the TJ-II Flexible Heliac at National Fusion Laboratory. (Author) 35 refs.

  1. Shutdown margin calculation during the fuel shuffling inside the Cofrentes Nuclear Power Plant core; Calculo del Margen de Parada durante el Barajado del Combustible dentro del Nucleo de C.N. Cofrentes

    Energy Technology Data Exchange (ETDEWEB)

    Tovar, H.; Rodriguez, D.; Albendea, M.; Crespo, A.

    2010-07-01

    The main characteristics of HERACLIO system are described in this paper. They present the results obtained during its application to the Cofrentes Recarga-17, when a element shuffling was made inside de core.

  2. Criticality and shielding calculations for containers in dry of spent fuel of TRIGA Mark III reactor of ININ; Calculos de criticidad y blindaje para contenedores en seco de combustible gastado del reactor Triga Mark III del ININ

    Energy Technology Data Exchange (ETDEWEB)

    Barranco R, F.

    2015-07-01

    In this thesis criticality and shielding calculations to evaluate the design of a container of dry storage of spent nuclear fuel generated in research reactors were made. The design of such container was originally proposed by Argentina and Brazil, and the Instituto Nacional de Investigaciones Nucleares (ININ) of Mexico. Additionally, it is proposed to modify the design of this container to store spent fuel 120 that are currently in the pool of TRIGA Mark III reactor, the Nuclear Center of Mexico and calculations and analyzes are made to verify that the settlement of these fuel elements is subcritical limits and dose rates to workers and the general public are not exceeded. These calculations are part of the design criteria for security protection systems in dry storage system (Dss for its acronym in English) proposed by the Nuclear Regulatory Commission (NRC) of the United States. To carry out these calculations simulation codes of Monte Carlo particle transport as MCNPX and MCNP5 were used. The initial design (design 1) 78 intended to store spent fuel with a maximum of 115. The ININ has 120 fuel elements and spent 3 control rods (currently stored in the reactor pool). This leads to the construction of two containers of the original design, but for economic reasons was decided to modify (design 2) to store in a single container. Criticality calculations are performed to 78, 115 and fresh fuel elements 124 within the container, to the two arrangements described in Chapter 4, modeling the three-dimensional geometry assuming normal operating conditions and accident. These calculations are focused to demonstrate that the container will remain subcritical, that is, that the effective multiplication factor is less than 1, in particular not greater than 0.95 (as per specified by the NRC). Spent fuel 78 and 124 within the container, both gamma radiation to neutron shielding calculations for only two cases were simulated. First actinides and fission products generated during irradiation of fuels, with MCNPX, then these data were obtained and used for the simulation with MCNP5 using conversion factors creep dose rate. The need to store the spent fuel (outside the reactor pool) leads to the creation of an alternative for its management, and the idea is to propose and evaluate a dry storage container arises. (Author)

  3. Retrospective study of the calculation of doses by Monte Carlo in extracranial stereotactic; Estudio retrospectivo del calculo de dosis mediante Monte Carlo en radioterapia estereotaxica extracraneal (SBRT) de pulmon

    Energy Technology Data Exchange (ETDEWEB)

    Zucca Aparicio, D.; Perez Moreno, J. M.; Fernandez Leton, P.; Garcia Ruiz-Zorrilla, J.; Minambres Moro, A.

    2013-07-01

    The objective of this work consists of the evaluation of those clinical parameters described in RTOG 0813 and 0915 RTOG protocols relevant applicable to PTV, lung tissue and healthy normal, of those patients treated in our institution since April 2008, calculated initially through Pencil Beam and recalculated currently using Monte Carlo is interesting remark that the RTOG 0813 Protocol replaces the previous RTOG 0236 which expressly mentioned do not make corrections by heterogeneity in the calculation of dose in lung lesions. (Author)

  4. Evaluation of a Monte Carlo calculation algorithm for clinical use extracranial stereotactic radiotherapy (SBRT); Evaluacion de un algoritmo de calculo Monte Carlo de uso clinico para radioterapia esterotaxica extracraneal (SBRT)

    Energy Technology Data Exchange (ETDEWEB)

    Zuca Aparicio, D.; Perez Moreno, J. M.; Fernandez Leton, P.; Garcia Ruiz-Zorrila, J.; Minambres Moro, A.

    2013-07-01

    At present it is not common to find commercial planning systems that incorporate dose calculation algorithms to do based on Monte Carlo [1,2] photons This paper summarizes the process followed in the evaluation of a dose calculation algorithm for MC beams of 6 MV photons from an accelerator dedicated to radiosurgery (SRS), cranial stereotactic radiotherapy (SRT) and extracranial (SBRT). (Author)

  5. Practical application of the tool calculation Monte Carlo MCVerif for checking for radiotherapy treatment; Aplicacion practica de la herramienta de calculo Monte Carlo MCVerif para la verificacion de tratamientos de radioterapia

    Energy Technology Data Exchange (ETDEWEB)

    Laliena Bielsa, V. M.; Garcia Romero, A.; Villa Gazulla, D.; Ortega Pardilla, P.; Calvo Carrillo, S.; Millan Cebrian, E.; Hernandez Vitorial, A.; Canellas Aznoz, M.

    2013-07-01

    The object of this work is to verify a patient group representative of the usual techniques of 3D conformal radiotherapy and IMRT performed in the radiotherapy service our hospital and thus validate the algorithm used commercial planning system. (Author)

  6. Calculation and analysis of hydrogen volume concentrations in the vent pipe rigid proposed for NPP-L V; Calculo y analisis de concentraciones volumetricas de hidrogeno en el tubo de venteo rigido propuesto para la CNLV

    Energy Technology Data Exchange (ETDEWEB)

    Gomez T, A. M.; Xolocostli M, V. [ININ, Carretera Mexico-Toluca s/n, 52750 Ocoyoacac, Estado de Mexico (Mexico); Lopez M, R.; Filio L, C. [Comision Nacional de Seguridad Nuclear y Salvaguardias, Dr. Jose Ma. Barragan No. 779, Col. Narvarte, 03020 Mexico D. F. (Mexico); Royl, P., E-mail: armando.gomez@inin.gob.mx [Karlsruhe Institute of Technology, Hermann-von-Helmholtz-Platz I, D-76344 Eggenstein-Leopoldshafen (Germany)

    2014-10-15

    In 2012 was modeled of primary and secondary container of the nuclear power plant of Laguna Verde (NPP-L V) for the CFD Gas-Flow code. These models were used to calculate hydrogen volume concentrations run release the reactor building in case of a severe accident. The results showed that the venting would produce detonation conditions in the venting level (level 33) and flammability at ground level of reload. One of the solutions to avoid reaching critical concentrations (flammable or detonable) inside the reactor building and thus safeguard the contentions is to make a rigid venting. The rigid vent is a pipe connected to the primary container could go to the level 33 of the secondary container and style fireplace climb to the top of the reactor building. The analysis of hydrogen transport inside the vent pipe can be influenced by various environmental criteria and factors vent, so a logical consequence of the 2012 analysis is the analysis of the gases transport within said pipe to define vent ideal conditions. For these evaluations the vent pipe was modeled with a fine mesh of 32 radial interior nodes and a coarse mesh of 4 radial interior nodes. With three-dimensional models were realized calculations that allow observing the influence of heat transfer in the long term, i.e. a complete analysis of exhaust (approx. 700 seconds). However, the most interesting results focus on the first milliseconds, when the H{sub 2} coming from the atmosphere of the primary container faces the air in the vent pipe. These first milliseconds besides allowing evaluating the detonation criteria in great detail in the different tubular sections similarly allow evaluating the pressure wave that occurs in the pipe and that at some point slows to the fluid on the last tubular section and could produce a detonation inside the pipe. Results are presented for venting fixed conditions, showing possible detonations into the pipe. (Author)

  7. Numerical Calculation of Transport Based on the Drift Kinetic Equation for plasmas in General Toroidal Magnetic Geometry; Calculo Numerico del Transporte mediante la Ecuacion Cinetica de Deriva para Plasmas en Geometria Magnetica Toroidal: Preliminares

    Energy Technology Data Exchange (ETDEWEB)

    Reynolds, J. M.; Lopez-Bruna, D.

    2009-12-11

    This report is the first of a series dedicated to the numerical calculation of the evolution of fusion plasmas in general toroidal geometry, including TJ-II plasmas. A kinetic treatment has been chosen: the evolution equation of the distribution function of one or several plasma species is solved in guiding center coordinates. The distribution function is written as a Maxwellian one modulated by polynomial series in the kinetic coordinates with no other approximations than those of the guiding center itself and the computation capabilities. The code allows also for the inclusion of the three-dimensional electrostatic potential in a self-consistent manner, but the initial objective has been set to solving only the neoclassical transport. A high order conservative method (Spectral Difference Method) has been chosen in order to discretized the equation for its numerical solution. In this first report, in addition to justifying the work, the evolution equation and its approximations are described, as well as the baseline of the numerical procedures. (Author) 28 refs.

  8. Dose calculations for a simplified Mammosite system with the Monte Carlo Penelope and MCNPX simulation codes; Calculos de dosis para un sistema Mammosite simplificado con los codigos de simulacion Monte Carlo PENELOPE y MCNPX

    Energy Technology Data Exchange (ETDEWEB)

    Rojas C, E.L.; Varon T, C.F.; Pedraza N, R. [ININ, 52750 La Marquesa, Estado de Mexico (Mexico)]. e-mail: elrc@nuclear.inin.mx

    2007-07-01

    The treatment of the breast cancer at early stages is of vital importance. For that, most of the investigations are dedicated to the early detection of the suffering and their treatment. As investigation consequence and clinical practice, in 2002 it was developed in U.S.A. an irradiation system of high dose rate known as Mammosite. In this work we carry out dose calculations for a simplified Mammosite system with the Monte Carlo Penelope simulation code and MCNPX, varying the concentration of the contrast material that it is used in the one. (Author)

  9. Advanced calculations developed for the ITER project within of engineering support framework contracts to F4E; Calculos avanzados desarrollados para el proyecto ITER dentro de los contratos marco de soporte de ingenieria para F4E

    Energy Technology Data Exchange (ETDEWEB)

    Bosch, C.; Polo, J.; Garcia Cid, J.; Guirao, J.; Fernandez, E.; Bayon, A.; Caixas, J.

    2013-07-01

    Present the different kind of analyses carried out within the engineering support framework contracts for F4E in the period 2009-2013 and its evolution according to project needs and Vacuum Vessel manufacturing status.

  10. Axial profiles of burned and fraction of holes for calculations of criticality with credit for BWR fuel burning; Perfiles axiales de quemado y fraccion de huecos para calculos de criticidad con credito al quemado para combustible BWR

    Energy Technology Data Exchange (ETDEWEB)

    Casado Sanchez, C.; Rubio Oviedo, P.

    2014-07-01

    This paper presents a method to define surround profiles of burning and fraction of holes suited for use in applications of credit to burning of BWR fuel from results obtained with the module STARBUCS of SCALE. (Author)

  11. Calculation of source term in spent PWR fuel assemblies for dry storage and shipping cask design; Calculo de los terminos fuente de combustibles irradiados PWR para el diseno de contenedores de almacenamiento y transporte

    Energy Technology Data Exchange (ETDEWEB)

    Fernandez, J. L.; Lopez, J.

    1986-07-01

    Using the ORIGEN-2 Coda, the decay heat and neutron and photon sources for an irradiated PWR fuel element have been calculated. Also, parametric studies on the behaviour of the magnitudes with the burn-up, linear heat power and irradiation and cooling times were performed. Finally, a comparison between our results and other design calculations shows a good agreement and confirms the validity of the used method. (Author) 6 refs.

  12. Neutron flux calculation and fluence in the encircling of the core and vessel of a reactor BWR; Calculo de flujo neutronico y fluencia en la envolvente del nucleo y la vasija de un reactor BWR

    Energy Technology Data Exchange (ETDEWEB)

    Martinez C, E.

    2011-07-01

    One of the main objectives related to the safety of any nuclear power plant, including the nuclear power plant of Laguna Verde is to ensure the structural integrity of reactor pressure vessel. To identify and quantify the damage caused by neutron irradiation in the vessel of any nuclear reactor, it is necessary to know both the neutron flux and the neutron fluence that the vessel has been receiving during its operation lifetime, and that the damage observed by mechanical testing are products of microstructural effects induced by neutron irradiation; therefore, it is important the study and prediction of the neutron flux in order to have a better understanding of the damage that these materials are receiving. The calculation here described uses the DORT code, which solves the neutron transport equation in discrete ordinates in two dimensions (x-y, r-{theta} and r-z), according to a regulatory guide, it should make an approximation of the neutron flux in three dimensions by the so called synthesis method. It is called in that way because it achieves a representation of 3 Dimensional neutron flux combining or summarizing the fluxes calculated by DORT r-{theta}, r-z and r. This work presents the application of synthesis method, according to Regulatory Guide 1190, to determine the 3 Dimensional fluxes in internal BWR reactor using three different spatial meshes. The results of the neutron flux and fluence, using three different meshes in the directions r, {theta} and z were compared with results reported in the literature obtaining a difference not larger than 9.61%, neutron flux reached its maximum, 1.58 E + 12 n/cm{sup 2}s, at a height H 4 (239.07 cm) and angle 32.236{sup o} in the core shroud and 4.00 E + 09 n/cm{sup 2}s at a height H 4 and angle 35.27{sup o} in the inner wall of the reactor vessel, positions that are consistent to within {+-}10% over the ones reported in the literature. (Author)

  13. Characterization program, management and isotopic inventory calculation, radiological and fuel thermal irradiated in nuclear power Cofrentes; Programa Caracterizacion Gestion y calculo del inventario isotopico, radiologico y termico del combustible irradiado en la Central Nuclear de Cofrentes

    Energy Technology Data Exchange (ETDEWEB)

    Albendea, M.; Diego, J. L. de; Urrea, M.

    2012-07-01

    Characterization is a very detailed and user-friendly program takes into account the history of irradiation individualized and real all the fuel, even taking into account the interim periods are periods of discharge and recharge cycles and which have not been used.

  14. Estimating effective wedge factor for enhanced dynamic wedge 2100CD a Varian Clinac; Calculo De factor cuna efectiva para cuna dinamica mejorada de un Clinac 2100CD de Varian

    Energy Technology Data Exchange (ETDEWEB)

    Pizarro Trigo, F.; Morillas Ruiz, J.; Nunuz Martinez, L.; Sanchez Jimenez, J.

    2011-07-01

    The purpose of this paper is to compare different methods of calculating the effective factor enhanced dynamic wedge (EDWF) with the values ??obtained in measurements of symmetric and asymmetric fields.

  15. Revision of the equation Calculated Cetane Index for the characteristics of diesel commercialized in the Parana-Brazil; Revisao da equacao de Calculo do Indice de Cetano para as caracteristicas do diesel comercializado no Parana

    Energy Technology Data Exchange (ETDEWEB)

    Souza, Tatiana Bittencourt de; Yamamoto, Carlos Itsuo; Cocco, Lilian Cristina [Universidade Federal do Parana (UFPR), Curitiba, PR (Brazil). Lab. de Analise de Combustiveis Automotivos (LACAUTets)

    2008-07-01

    This work presents the development of models for Calculated Cetane Index (CCI) determination with the purpose of tailor it to the diesel oil sold in Brazil, using optimization techniques. As the diesel is the main fuel on the Brazilian territory, their quality is of great importance. The CCI calculation is important to evaluate the diesel quality. The standard ASTM D 4737 does not take into account the presence of cetane booster additive and biodiesel, which creates the need to recast the equation of the CCI determination. About 300 representative samples were selected of diesel in Parana, during the 2006 to 2007 period, which had their physic-chemical properties determined using the methodology adopted by the ANP - the Brazilian petroleum, natural gas and biofuel agency. The Derived Cetane Number was obtained in the IQT apparatus and several models were proposed, all with better predictive capability than the equation of the standard ASTM D 4737. It is pointed out that biodiesel can act as cetane booster additive depending upon its origin, mostly in concentrations above 5%. The methodology can be expanded to generate a representative equation for the diesel sold in the whole Brazilian territory. (author)

  16. Dosimetric calculations by Monte Carlo for treatments of radiosurgery with the Leksell Gamma Knife, homogeneous and non homogeneous cases; Calculos dosimetricos por Monte Carlo para tratamientos de radiocirugia con el Leksell Gamma Knife, casos homogeneo y no homogeneo

    Energy Technology Data Exchange (ETDEWEB)

    Rojas C, E.L. [ININ, 52045 Ocoyoacac, Estado de Mexico (Mexico); Lallena R, A.M. [Universidad de Granada (Spain)

    2004-07-01

    In this work dose profiles are calculated that are obtained modeling treatments of radiosurgery with the Leksell Gamma Knife. This was made with the simulation code Monte Carlo Penelope for an homogeneous mannequin and one not homogeneous. Its were carried out calculations with the irradiation focus coinciding with the center of the mannequin as in near areas to the bone interface. Each one of the calculations one carries out for the 4 skull treatment that it includes the Gamma Knife and using a model simplified of their 201 sources of {sup 60} Co. It was found that the dose profiles differ of the order of 2% when the isocenter coincides with the center of the mannequin and they ascend to near 5% when the isocenter moves toward the skull. (Author)

  17. A combination between the differential and the perturbation theory methods for calculating sensitivity coefficients; Uma combinacao entre os metodos diferencial e da teoria de pertubacao para o calculo dos coeficientes de sensibilidade

    Energy Technology Data Exchange (ETDEWEB)

    Borges, Antonio Andrade

    1998-07-01

    A new method for the calculation of sensitivity coefficients is developed. The new method is a combination of two methodologies used for calculating theses coefficients, which are the differential and the generalized perturbation theory methods. The method utilizes as integral parameter the average flux in an arbitrary region of the system. Thus, the sensitivity coefficient contains only the component corresponding to the neutron flux. To obtain the new sensitivity coefficient, the derivatives of the integral parameter, {phi}, with respect to {sigma} are calculated using the perturbation method and the functional derivatives of this generic integral parameter with respect to {sigma} and {phi} are calculated using the differential method. (author)

  18. Numerical Calculation of Transport Based on the Drift-Kinetic Equation for Plasmas in General Toroidal Magnetic Geometry: Numerical Methods; Calculo Numerico de Transporte mediante la Ecuacion Cinetica de Deriva para Plasmas en Geometria Magnetica Toroidal: Metodos Numericos

    Energy Technology Data Exchange (ETDEWEB)

    Reynolds, J. M.; Lopez-Bruna, D.

    2009-10-12

    In this report we continue with the description of a newly developed numerical method to solve the drift kinetic equation for ions and electrons in toroidal plasmas. Several numerical aspects, already outlined in a previous report [Informes Tecnicos Ciemat 1165, mayo 2009], will be treated now in more detail. Aside from discussing the method in the context of other existing codes, various aspects will be now explained from the viewpoint of numerical methods: the way to solve convection equations, the adopted boundary conditions, the real-space meshing procedures along with a new software developed to build them, and some additional questions related with the parallelization and the numerical integration. (Author) 16 refs.

  19. Application of shielding calculation of high-energy linear accelerators based on the NCRP-151 protocol; Aplicacion de calculo de blindajes de aceleradores lineales de alta energia basada en el protocolo NCRP-151

    Energy Technology Data Exchange (ETDEWEB)

    Torres Pozas, S.; Monja Rey, P. de la; Sanchez Carrasca, M.; Yanez Lopez, D.; Macias Verde, D.; Martin Oliva, R.

    2011-07-01

    In recent years, the progress experienced in cancer treatment with ionizing radiation can deliver higher doses to smaller volumes and better shaped, making it necessary to take into account new aspects in the calculation of structural barriers. Furthermore, given that forecasts suggest that in the near future will install a large number of accelerators, or existing ones modified, we believe a useful tool to estimate the thickness of the structural barriers of treatment rooms. The shielding calculation methods are based on standard DIN 6847-2 and the recommendations given by the NCRP 151. In our experience we found only estimates originated from the DIN. Therefore, we considered interesting to develop an application that incorporates the formulation suggested by the NCRP, together with previous work based on the rules DIN allow us to establish a comparison between the results of both methods. (Author)

  20. Methodologies for the calculation of relative efficiency: description and application for natural gas distributors in Latin America; Metodologias para el calculo de eficiencia relativa: descripcion y aplicacion para distribuidores de gas natural en Latinoamerica

    Energy Technology Data Exchange (ETDEWEB)

    Escandon Jimenez, Alejandro C. [Mexico, D.F. (Mexico)

    2004-06-15

    The importance of knowing the performance of the companies within a productive sector has increased in the last years, demonstrating the necessity of knowing and applying tools that help us to know the performance of a company with respect to the others with which it is competing. Recently, a great variety of tools have been developed to know the efficiency or productivity of a company in a certain sector. Nevertheless, the two more used, up to now, are those that will be described in the present in study. Finally, one practical example of the two methodologies will be presented, applied to the natural gas industry for distributing companies of this energy in Latin America. [Spanish] La importancia de conocer el desempeno de las empresas dentro de un sector productivo ha incrementado en los ultimos anos, demostrando la necesidad de conocer y aplicar herramientas que nos ayuden a conocer el desempeno de una empresa con respecto a las demas con las cuales se esta compitiendo. Recientemente, se han desarrollado gran variedad de herramientas para conocer la eficiencia o productividad de una compania en un determinado sector. Sin embargo, las dos mas utilizadas, hasta el momento, son las que se describiran en el presente estudio. Finalmente, se presentara un ejemplo practico de las dos metodologias, aplicado a la industria del gas natural para companias distribuidoras de este energetico en Latinoamerica.