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Search Results: 1 - 10 of 313017 matches for " J. J. Su?ol "
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Phase Transformation in the Ball Milled Fe31Co31Nb8B30 Powders  [PDF]
S. Azzaza, S. Alleg, J. J. Suol
Advances in Materials Physics and Chemistry (AMPC) , 2013, DOI: 10.4236/ampc.2013.31A011
Abstract:

The mechanical alloying process has been used to prepare nanostructured Fe31Co31Nb8B30 (wt%) alloy from pure elemental powders in a high energy planetary ball-mill Retsch PM400. Microstructural changes, phase transformation and kinetics were studied by X-ray diffraction, differential scanning calorimetry and M?ssbauer spectrometry. The crystallite size reduction down the nanometer scale (~8 nm) is accompanied by the introduction of internal strains up to 1.8% (root-mean square strain, rms). Further milling time leads to the formation of partially paramagnetic amorphous structure in which bcc FeCo nanograins are embedded. The kinetics of amorphization during the milling process can be described by two regimes characterized by different values of the Avrami parameter n1 = 1.41 and n2 = 0.34. The excess enthalpy due to the high density of defects is released at temperatures below 300°C. The glass transition temperature increases with increasing milling time.

Estudio sobre la resistencia química de baldosas cerámicas no-esmaltadas para pavimentos industriales
Escoda, L.,Lledó, M.,Suol, J. J.,Roura, P.
Boletín de la Sociedad Espa?ola de Cerámica y Vidrio , 2003,
Abstract: The chemical resistance of ceramic tiles is the subject of the European Standard UNE-EN ISO 10545-13. In order to evaluate the effect of aqueous solutions of several chemicals agents on the aspect of the tile surface, this standard establishes a series of tests at room temperature followed by visual inspection. According to this standard the tiles of this study are classified as being of maximum resistance (UHA). However operating conditions can be more aggressive than those detailed in the standard. So, a systematic study has been undertaken. In the present work, the effect of aqueous solutions of several organic and inorganic acids on the tile surface is evaluated. Samples immersed in different solutions are subjected to the following conditions: T= 60o C; pH=2 and to agitation processes. Visual analysis, as well as optical microscopy and scanning electron microscopy (SEM) were performed in order to determine the possible variation of the superficial aspect of tiles. Moreover, atomic absorption spectrophotometry has been used in order to obtain quantitative information concerning the solubility of system M (III)-L (M= Fe; L= H2O or L= ligand). The results obtained show, in all cases, a progressive dissolution of iron oxide precipitates presents in the ceramic body. La resistencia al ataque químico de baldosas cerámicas está contemplada en la Norma UNE-EN ISO 10545-13. Dicha norma establece una serie de ensayos a temperatura ambiente en los cuales se analiza visualmente el efecto sobre el aspecto de la superficie de disoluciones acuosas de diversos productos químicos. Según esta norma, las baldosas objeto de nuestro estudio están clasificadas como de máxima resistencia (UHA). Sin embargo, las condiciones a las que pueden verse sometidas pueden ser considerablemente más agresivas que las contempladas en la Norma, por lo que es necesario un estudio sistemático. En el presente trabajo, se ha dise ado un procedimiento para evaluar el efecto de diversas disoluciones acuosas de diversos ácidos orgánicos e inorgánicos. Las probetas sumergidas en las diferentes soluciones han estado sometidas a las siguientes condiciones: T = 60oC; pH=2 y procesos de agitación. El posible ataque químico de la superficie de las baldosas se ha evaluado por observación visual así como por microscopía óptica y microscopía electrónica de barrido (SEM). Complementariamente se ha analizado por absorción atómica la eventual disolución de diversos iones metálicos en el sistema M (III)-L(M = Fe; L = H2O o L = ligando). El análisis ha revelado en todas las soluciones la disolución progre
Characterization of Mechanically Alloyed Nanocrystalline Fe(Al): Crystallite Size and Dislocation Density
M. Mhadhbi,M. Khitouni,L. Escoda,J. J. Suol,M. Dammak
Journal of Nanomaterials , 2010, DOI: 10.1155/2010/712407
Abstract: A nanostructured disordered Fe(Al) solid solution was obtained from elemental powders of Fe and Al using a high-energy ball mill. The transformations occurring in the material during milling were studied with the use of X-ray diffraction. In addition lattice microstrain, average crystallite size, dislocation density, and the lattice parameter were determined. Scanning electron microscopy (SEM) was employed to examine the morphology of the samples as a function of milling times. Thermal behaviour of the milled powders was examined by differential scanning calorimetry (DSC). The results, as well as dissimilarity between calorimetric curves of the powders after 2 and 20?h of milling, indicated the formation of a nanostructured Fe(Al) solid solution. 1. Introduction Mechanical alloying (MA) is a technique commonly used to obtain supersaturated solid solutions, compounds with high energy of mixing, and alloys of combinations of elements which do not show appreciable solubility in their equilibrium phase diagrams [1–3]. The Fe-Al system is an example of a binary system with a low solid miscibility at room temperature; however, by means of MA Fe(Al) solid solutions have been obtained in almost all the compositional range. In recent years, a number of studies have been reported on mechanical alloying of FeAl. It is established that the formation of the supersaturated solid solution (SSS) α-Fe(Al) as a final product of MA takes place with at % Al though in a number of papers the formation of SSS was found with at % Al [4–9]. For instance, Zeng and Baker [9] investigated the effect of milling time on the crystallite size, lattice strain, and lattice parameter of Fe-40 at % Al powder mixture. According to their results, the crystallite size is less than 7?nm after 4?h, indicating a rapid decrease of size, but milling for more than 6?h results in some increase in the nanocrystalline size. They attributed this fact to the dynamic recrystallization and/or nanocrystalline grain growth. The same results were shown in the case of MA Fe-45 at % Al [10]. Moreover, the lattice parameter also increased at first up to 10?h milling, then decreased. This decrease has attributed to the oxidation during milling, which decreases the Al content. In addition, Wolski et al. [11] studied the effect of milling conditions on the Fe-35 at % Al intermetallic formation by MA. According to their investigation, this process occurred in two steps: a nanocrystallization step and an FeAl formation step. FeAl formation started rapidly by the creation of Al-rich and Fe-rich solid solutions; the
Development of Fe-based nanocrystalline materials by mechanical alloying
Suol, J. J.,González, A.,Escoda, L.,Mora, M. T.
Revista de Metalurgia , 2008,
Abstract: Two alloys, Fe80NbB10 and Fe70Ni14Zr6B10, were produced by mechanical alloying. The formation of the nanocrystallites (about 7-8 nm at 80h MA) was detected by X-ray diffraction. After milling for 80 h, differential scanning calorimetry scans show low-temperature recovery processes and several crystallization processes related with crystal growth and reordering of crystalline phases. The apparent activation energy values are 315 ± 40 kJ mol–1 for alloy A, and 295 ± 20 kJ mol–1 and 320 ± 25 kJ mol–1 for alloy B. Furthermore, a melt-spun Fe-based ribbon was mechanically alloyed to obtain a powdered-like alloy. The increase of the rotation speed and the ball-to-powder weight ratio reduces the necessary time to obtain the powdered form. Dos aleaciones, Fe80Nb10B10 (A) y Fe70Ni14Zr6B10 (B), han sido producidas por aleado mecánico. Mediante difracción de rayos X se ha detectado la formación de nanocristales (7-8 nm a las 80 h de aleado). Tras molturar 80 h, las curvas calorimétricas muestran procesos exotérmicos asociados a la relajación estructural y al crecimiento cristalino y reordenación de la fase cristalina. Los valores de la energía aparente de activación de las cristalizaciones son 315 ± 40 kJ mol–1 para la aleación A, y 295 ± 20 kJ mol–1 y 320 ± 25 kJ mol–1 para la aleación B. Por otra parte, se ha procedido a la molturación de una cinta de una aleación de base hierro hasta obtener un material en forma de polvo. El incremento de la velocidad de rotación y de la relación en peso bolas polvo reduce el tiempo necesario para obtener este material.
Desarrollo de materiales de base Fe a partir de la síntesis de precursores por aleado mecánico
González, A.,Suol, J. J.,Escoda, L. L.,Artalejo, L. L.
Boletín de la Sociedad Espa?ola de Cerámica y Vidrio , 2005,
Abstract: Fe rich alloys with ZrNi or Nb and with non metallic B were developed by means of mechanical alloying. The material is nanocrystalline with a minoritary amorphous phase (about 12%). The reduction of the crystallite size is favoured by the addition of Zr, Nb or B. The mechanical alloying parameters were optimised to obtain a nanocrystalline state at low milling time. Furthermore, the apparent activation energy of the crystallisation processes was obtained by thermal treatment, controlled by differential scanning calorimetry. Typical values between 280 and 410 kJ mol-1 are associated to crystalline growth. The control of the crystal size is related to the kinetic study of the non-equilibrium transformations where the incipient phase as different composition that the initial phase. Se han producido mediante síntesis mecánica aleaciones ricas en Fe, con Zr o Nb y con un no metal, B obteniéndose materiales nanoestructurados con una incipiente fase amorfa (entorno 12%). Tanto el Zr y el Nb como el B facilitan la reducción del tama o de los nanocristales. Se han optimizado las condiciones de proceso, minimizando el tiempo de molturación. Además, el posterior tratamiento térmico, controlado mediante calorimetría diferencial, de las diferentes aleaciones permite obtener la energía de activación de los procesos de cristalización, con valores entre 280 y 410 kJ mol-1 asociados al crecimiento cristalino. El control del tama o de los nanocristales se enmarca en el estudio de la cinética de las transformaciones fuera del equilibrio en las que la fase incipiente tiene composición diferente a la de la fase inicial.
Large lymph node size harvested as prognostic factor in gastric cancer?
Espín,F.; Bianchi,A.; Llorca,S.; Pulido,L.; Feliu,J.; Cruz,J. de-la; Palomera,E.; García,O.; Remon,J.; Suol,X.;
Revista Espa?ola de Enfermedades Digestivas , 2010, DOI: 10.4321/S1130-01082010000300003
Abstract: objective: knowledge regarding prognostic factors in gastric cancer is essential to decide on single patient management. we aim to establish the value of large lymph node size in order to improve perioperative approach. material and methods: charts of one hundred and twenty-eight consecutive patients undergoing gastrectomy for resectable gastric cancer were reviewed between january 1996 and december 2005. patients were split in two groups according to large lymph node size harvested, group i, lymph node size ≤ 10 mm and group ii, lymph node size > 10 mm. overall five-year survival related to cancer were analyzed as a main endpoint. prognostic factors as tnm classification and degree of differentiation have been considered. results: there were no differences regarding age and gender (67.4 vs. 64; p = 0.34 and 66,1 vs. 68,1%; p = 0.27, respectively). nevertheless, a significant difference has been found according to t1-t2 of tnm stage (78.1 vs. 39.1% p = < 0.001), for n grade staging, has statistical signification for grade n0 (62.7 vs. 30.5%; p < 0.001), and for ia and ib stages (57.6 vs. 17.4%). five years overall survival has a great statistical signification (p log-rank = 0.0003), however, overall survival between groups with positive lymph nodes according to lymph node size was close to signification, (p log-rank = 0.0636). conclusions: our data indicates that large lymph node size could be a powerful predictor for overall survival in gastric cancer, when it could be evaluated in preoperative period. in our opinion lymph node size should be considered for perioperative chemotherapy schemas. detection and staging techniques for lymph node affection acquire much more importance.
Tailoring of Magnetocaloric Effect in Metamagnetic Shape Memory Alloy
W. O. Rosa,L. González,J. García,T. Sánchez,V. Vega,Ll. Escoda,J. J. Su ol,J. D. Santos,M. J. P. Alves,R. L. Sommer,V. M. Prida,B. Hernando
Physics Research International , 2012, DOI: 10.1155/2012/794171
Abstract: We investigate the direct and inverse magnetocaloric effect in Ni45.5Mn43.0In11.5 Heusler alloy ribbons comparing the results obtained for the as-quenched sample with the ones after different annealing procedures. An enhancement and shift of the entropy maximum to near room temperature is observed in all annealed samples. A remarkable magnetocaloric effect is observed in samples with short-time treatment (10 minutes) and at the lowest annealing temperature. We show that the suppressing of uncompensated martensitic transition and thermal hysteresis are both influenced by the heat treatment. Also, an improvement on Curie’s temperature is observed and, at low magnetic field, it has been risen up to 310 K. Our results demonstrate that the martensitic transformation is highly sensitive to the applied magnetic field and also to the annealing treatment, which means that the magnetocaloric effect can be tuned showing different behaviors for each sample.
Tailoring of Magnetocaloric Effect in Metamagnetic Shape Memory Alloy
W. O. Rosa,L. González,J. García,T. Sánchez,V. Vega,Ll. Escoda,J. J. Suol,J. D. Santos,M. J. P. Alves,R. L. Sommer,V. M. Prida,B. Hernando
Physics Research International , 2012, DOI: 10.1155/2012/794171
Abstract: We investigate the direct and inverse magnetocaloric effect in Ni45.5Mn43.0In11.5 Heusler alloy ribbons comparing the results obtained for the as-quenched sample with the ones after different annealing procedures. An enhancement and shift of the entropy maximum to near room temperature is observed in all annealed samples. A remarkable magnetocaloric effect is observed in samples with short-time treatment (10 minutes) and at the lowest annealing temperature. We show that the suppressing of uncompensated martensitic transition and thermal hysteresis are both influenced by the heat treatment. Also, an improvement on Curie’s temperature is observed and, at low magnetic field, it has been risen up to 310?K. Our results demonstrate that the martensitic transformation is highly sensitive to the applied magnetic field and also to the annealing treatment, which means that the magnetocaloric effect can be tuned showing different behaviors for each sample. 1. Introduction Many first-order phase transition materials have been found to exhibit giant magnetocaloric effect (MCE) [1–3]. Currently, the search for a cheap magnetic material which exhibit a large MCE that works in the temperature range of 100 up to 300?K for a magnetic field variation of ?kOe is carried out. The most extensively studied Heusler alloys have those of the Ni-Mn-Ga system, nevertheless to overcome some of the problems related with practical applications (such as the high cost of Gallium and the usually low martensitic transformation temperature), the search for Ga-free alloys has been recently attempted. In order to reduce such costs and to improve the martensitic transition temperature, the substitution of Ga is proposed and, in particular, by introducing In or Sn [4–7]. These ferromagnetic shape memory alloys (FSMA) exhibit ferromagnetic and shape memory effect simultaneously. The ferromagnetic shape memory effect can be controlled by temperature, stress, and by magnetic field. Recently, Ni-Mn-In Heusler alloys have drawn much attention due to their potential as ferromagnetic shape memory alloys, which undergo a thermoelastic martensitic transformation (MT) from parent austenitic phase to a martensitic one on cooling [8]. These alloys exhibit notable sensitivity of MT to the applied magnetic field, they seem to be among the most suitable for the room temperature (RT) applications for example, in micro and nanomechanics devices and in alternative energy technologies, due to the giant magnetocaloric effect (MCE) observed in this alloys [9, 10]. Moreover, some authors have reported that such
Reconstrucción nasal total: a propósito de un caso
Serracanta Domènech,J.; Vázquez Fernández,D.; López Munné,D.; Gornés Benejam,B.; Suol Sala,X.;
Cirugía Plástica Ibero-Latinoamericana , 2007, DOI: 10.4321/S0376-78922007000400007
Abstract: we present the case of a 90 year-old woman with a scamous cell carcinoma located on the nose. a nasal defect must be analyzed in terms of anatomic tissue loss and aesthetic three-dimensional subunits, starting from de inside of the nose and progressing outward, layer by layer. the case that follows demostrates the use of a septal pivot flap, an olecranum bone graft restored the dorsal subunit, and bilateral conchal cartilage grafts were fashioned into new alar cartilages. bilateral nasolabial flaps were needed and finally the skin cover defect was resurfaced as a total nasal unit made of columela, dorsum, alar units and portions of the nasal sidewalls bilaterally with a forehead flap. four weeks after the initial reconstruction, the forehead pedicle was divided. at this moment the woman is alive and under periodical revision.
Real Exchange Rate Targets, Nominal Exchange Rate Policies, and Inflation Real Exchange Rate Targets, Nominal Exchange Rate Policies, and Inflation
J. Sa?ol Lizondo
Revista de Análisis Económico (RAE) , 1991,
Abstract: Real Exchange Rate Targets, Nominal Exchange Rate Policies, and Inflation Thh paper examines the implications of some nominal exchange rate policies aimed or attaining a given real exchange rate target. A policy rule that sets the rate of nominal depreciation as a function of the departures of the real exchange rate from its target level is unable to achieve the target. In contrast, a policv rule that sets the change in the rate of depreciation as a function of those departures may lead the economy to the target, under certain conditions. However, this policy could also lead the economy to a process of accelerating inflation.
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