761 resultados para Y(1.84)Lao(0.16)O(3)


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Después de una laparotomía del 70 al 95de pacientes tienen algún grado de adherencias, las que se manifestarán dependiendo de su consistencia y ubicación con cuadros clínicos de obstrucción intestinal agudos o crónicos, dolor abdominal crónico de casa no bien definido, dispareunias, infertilidad. El tratar la causa y el lavado de cavidad peritoneal son puntales principales en el tratamiento de la inflamación peritoneal desencadenante de la formación de adherencias. Para el lavado los cristaloides son los más indicados y de ellos la solución salñina y el lactato de Ringer los más usados. El objetivo fue conocer la capacidad para disminuir la formación de adherencias intraabdominales con el uso de lactato de ringer en comparación con la solución salina al contacto con el peritoneo, en ausencia de patología abdominal, en ratas Wistar. Para esto se realizó un estudio experimental clínico controlado aleatorizado en ratas wistar de laboratorio, formando dos grupos de 38 especímenes en cada uno, que cumplan los criterios de inclusión y exclusión, a las cuales les introdujo 5cc, de lactato de ringer y el otro grupo 5cc de solución salina al 0.9a 37 grados Celsius en la cavidad abdominal por punción con aguja Verres. A las 6 semanas se sacrificó a los animales y se realizó una valoración de las adherencias con clasificación macroscópica y estudio microscópico. De 75 casos, 35 del grupo de Lactato de Ringer y 36 del grupo de Solución salina, solamente 3 (8,10) ratas del grupo de Lactato de Ringer y 3 (7,89) del grupo de Solución Salina presentaron adherencias intraperitoneales. RR: 0,97 (0,18-5,15)

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Introducción: Los Desórdenes Musculo-Esqueléticos (DME) tienen origen multifactorial. En Colombia corresponden al principal grupo diagnóstico en procesos relacionados con la determinación de origen y pérdida de capacidad laboral. Objetivo: Determinar la relación entre síntomas musculo-esqueléticos y factores relacionados con la carga física en trabajadores de una empresa dedicada a la venta y distribución de medicamentos y equipos médicos, Bogotá (Colombia), en el año 2015. Materiales y Métodos: Estudio de corte transversal en 235 trabajadores. Se incluyeron variables sociodemográficas, ocupacionales y las relacionadas con los síntomas musculoesqueléticos y carga física. Se utilizó en cuestionario ERGOPAR. Para el análisis se utilizó la Prueba Exacta de Fisher, el Odds Ratio (OR) con el Intervalo de Confianza (IC) del 95%. Se realizó el análisis Multivariado con Regresión Logística Binaria. Resultados: La prevalencia de síntomas relacionados con DME fue de 79,2%, siendo más prevalente en cuello, hombros y columna dorsal (48,1%), seguido por columna lumbar (35,3%). Se encontró una asociación entre síntomas en cuello, hombros y/o columna dorsal con el sexo femenino (p=0,005, OR=2,33, 95%IC: 1,2-4,2); adoptar postura bípeda menos de 30 minutos (p=0,004, OR=3,34, 95%IC: 1,4-7,6); adoptar postura cabeza/cuello inclinado hacia delante entre 30 minutos y 2 horas (p=0,007, OR=3,25, 95%IC :1,3-7,7) y en columna lumbar con adoptar postura espalda/tronco hacia delante entre 30 minutos y 2 horas (p=0,001, OR=4,27, 95%IC: 1,7-10,3); y la antigüedad en el cargo entre 1 y 5 años (p=0,009, OR=3,47, 95%IC: 1,3-8,8). Conclusión: Las posturas bípedas con y sin desplazamiento, inclinaciones de tronco y cabeza, transporte manual de cargas, sexo femenino, antigüedad en el cargo y edad están asociadas conjuntamente al riesgo para presentar DME.

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This paper reports on the liquid-helium-temperature (5 K) electron paramagnetic resonance (EPR) spectra of Cr3+ ions in the nanoparticles of SnO2 synthesized at 600 degrees C with concentrations of 0%, 0.1%, 0.5%, 1%, 1.5%, 2.0%, 2.5%, 3.0%, 5.0%, and 10%. Each spectrum may be simulated as overlap of spectra due to four magnetically inequivalent Cr3+ centers characterized by different values of the spin-Hamiltonian parameters. Three of these centers belong to Cr3+ ions in orthorhombic sites, situated near oxygen vacancies, characterized by very large zero-field splitting parameters D and E, presumably due to the presence of nanoparticles in the samples. The fourth EPR spectrum belongs to the Cr3+ ions situated at sites with tetragonal symmetry, substituting for the Sn4+ ion, characterized by a very small value of D. In addition, there appears a ferromagnetic resonance line due to oxygen defects for samples with Cr3+ concentrations of <= 2.5%. Further, in samples with Cr3+ concentrations of >2.5%, there appears an intense and wide EPR line due to the interactions among the Cr3+ ions in the clusters formed due to rather excessive doping; the intensity and width of this line increase with increasing concentration. The Cr3+ EPR spectra observed in these nanopowders very different from those in bulk SnO2 crystals.

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In the title compound, C17H15ClN2O, the quinoline ring system is nearly planar, with a maximum deviation from the mean plane of 0.074 (2) angstrom, and makes a dihedral angle of 81.03 (7)degrees with the pyridone ring. The crystal packing is stabilized by pi-pi stacking interactions between the pyridone and benzene rings of the quinoline ring system [centroid-centroid distance = 3.6754 (10) angstrom]. Furthermore, weak intermolecular C-H center dot center dot center dot O hydrogen bonding links molecules into supramolecular chains along [001].

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Grain size has marked effects on charge-ordering and other properties of Nd(0.5)A(0.5)MnO(3) (A=Ca or Sr). Thus, the anti-ferromagnetic (AFM) transition in Nd0.5Ca0.5MnO3 is observed distinctly only in samples sintered at 1273 K or higher. The sample with a small grain size (sintered at 1173 K) shows evidence for greater ferromagnetic (FM) interaction at low temperatures, probably due to phase segregation. The FM transition as well as the charge-ordering transition in Nd0.5Sr0.5MnO3 becomes sharper in samples sintered at 1273 K or higher. The sample sintered at 1173 K does not show the AFM-CO transition around 150 K and is FM down to low temperatures; the apparent T-c-T-co gap decreases with the increase in the grain size. The samples sintered at lower temperatures (<1673 K) show evidence for greater segregation of the AFM and FM domains. (C) 2002 Elsevier Science Ltd. All rights reserved.

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We present an extensive study on magnetic and transport properties of La(0.85)Sr(0.15)CoO(3) single crystals grown by a float zone method to address the issue of phase separation versus spin-glass (SG) behavior. The dc magnetization study reveals a kink in field-cooled magnetization, and the peak in the zero-field-cooling curve shifts to lower temperature at modest dc fields, indicating the SG magnetic phase. The ac susceptibility study exhibits a considerable frequency-dependent peak shift (similar to 4 K) and a time-dependent memory effect below the freezing temperature. In addition, the characteristic time scale tau(0) estimated from the frequency-dependent ac susceptibility measurement is found to be similar to 10(-13) s, which matches well with typical values observed in canonical SG systems. The transport relaxation study evidently demonstrates the time-dependent glassy phenomena. In essence, all our experimental results corroborate the existence of SG behavior in La(0.85)Sr(0.15)CoO(3) single crystals.

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Results of a study of dc magnetization M(T,H), performed on a Nd(0.6)Pb(0.4)MnO(3) single crystal in the temperature range around T(C) (Curie temperature) which embraces the supposed critical region \epsilon\=\T-T(C)\/T(C)less than or equal to0.05 are reported. The magnetic data analyzed in the critical region using the Kouvel-Fisher method give the values for the T(C)=156.47+/-0.06 K and the critical exponents beta=0.374+/-0.006 (from the temperature dependence of magnetization) and gamma=1.329+/-0.003 (from the temperature dependence of initial susceptibility). The critical isotherm M(T(C),H) gives delta=4.54+/-0.10. Thus the scaling law gamma+beta=deltabeta is fulfilled. The critical exponents obey the single scaling equation of state M(H,epsilon)=epsilon(beta)f(+/-)(H/epsilon(beta+gamma)), where f(+) for T>T(C) and f(-) for T

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Homogeneous thin films of Sr(0.6)Ca(0.4)TiO(3) (SCT40) and asymmetric multilayer of SrTiO(3) (STO) and CaTiO(3) (CTO) were fabricated on Pt/Ti/SiO(2)/Si substrates by using pulsed laser deposition technique. The electrical behavior of films was observed within a temperature range of 153 K-373 K. A feeble dielectric peak of SCT40 thin film at 273 K is justified as paraelectric to antiferroelectric phase transition. Moreover, the Curie-Weiss temperature, determined from the epsilon'(T) data above the transition temperature is found to be negative. Using Landau theory, the negative Curie-Weiss temperature is interpreted in terms of an antiferroelectric transition. The asymmetric multilayer exhibits a broad dielectric peak at 273 K. and is attributed to interdiffusion at several interfaces of multilayer. The average dielectric constants for homogeneous Sr(0.6)Ca(0.4)TiO(3) films (similar to 650) and asymmetric multilayered films (similar to 350) at room temperature are recognized as a consequence of grain size effect. Small frequency dispersion in the real part of the dielectric constants and relatively low dielectric losses for both cases ensure high quality of the films applicable for next generation integrated devices. (C) 2011 Elsevier B.V. All rights reserved.

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Skutterudites Fe(0.)2Co(3.8)Sb(12),Te-x (x = 0, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6) were synthesized by induction melting at 1273 K, followed by annealing at 923 K for 144 h. X-ray powder diffraction and electron microprobe analysis confirmed the presence of the skutterudite phase as the main phase. The temperature-dependent transport properties were measured for all the samples from 300 to 818 K. A positive Seebeck coefficient (holes are majority carriers) was obtained in Fe0.2Co3.8Sb 12 in the whole temperature range. Thermally excited carriers changed from n-type to p-type in Fe(0.)2Co(3.8)Sb(12),Te-x 19Te0.1 at 570 K, while in all the other samples, Fe(0.)2Co(3.8)Sb(12),Te-x (x = 0.2, 0.3, 0.4, 0.5, 0.6) exhibited negative Seebeck coefficients in the entire temperature range measured. Whereas for the alloys up to x = 0.2 (Fe(0.)2Co(3.8)Sb(12),Te-x ) the electrical resistivity decreased by charge compensation, it increased for x> 0.2 with an increase in Te content as a result of an increase in the electron concentration. The thermal conductivity decreased with Te substitution owing to carrier phonon scattering and point defect scattering. The maximum dimensionless thermoelectric figure of merit, ZT = 1.04 at 818 K, was obtained with an optimized Te content for Fe0.2Co3.8Sb1 1.5Te0.5 and a carrier concentration of,,J1/ =- 3.0 x 1020 CM-3 at room temperature. Thermal expansion (a = 8.8 x 10-6 K-1), as measured for Fe(0.)2Co(3.8)Sb(12),Te-x , compared well with that of undoped Co4Sb12. A further increase in the thermoelectric figure of merit up to ZT = 1.3 at 820 K was achieved for Fe(0.)2Co(3.8)Sb(12),Te-x , applying severe plastic deformation in terms of a high-pressure torsion process. (C) 2013 Acta Materialia Inc. Published by Elsevier Ltd. All rights reserved.

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The frequency-dependent dielectric relaxation of Pb0.94Sr0.06](Mn1/3Sb2/3)(0.05)(Zr0.52Ti0.48)(0.95)]O-3 ceramics, synthesized in pure perovskite phase by a solid-state reaction technique is investigated in the temperature range from 303 to 773 K by alternating-current impedance spectroscopy. Using Cole-Cole model, an analysis of the imaginary part of the dielectric permittivity with frequency is performed assuming a distribution of relaxation times. The scaling behavior of the imaginary part of the electric modulus suggests that the relaxation describes the same mechanism at various temperatures. The variation of dielectric constant with temperature is explained considering the space-charge polarization. The SEM indicates that the sample has single phase with an average grain size similar to 14.2 mu m. The material exhibits tetragonal structure. A detailed temperature dependent dielectric study at various frequencies has also been performed. (C) 2013 Elsevier B.V. All rights reserved.