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Search Results: 1 - 10 of 15511 matches for " Pedro; Matutes "
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Leucemia linfoma T del adulto en Chile.: Estudio clínico-patológico y molecular de 26 pacientes Adult T cell leukemia lymphoma in Chile.: A clinico pathological and molecular study of 26 patients
M Elena Cabrera C,Silvia Labra G,Pedro Meneses C,Estella Matutes
Revista médica de Chile , 1999,
Abstract: Background: Adult T cell leukemia lymphoma is a lymphoproliferative syndrome etiologically associated to human T cell lymphotropic virus type I. Aim: To describe the clinical and laboratory features of 26 Caucasian Chilean patients, with HTLV-I positive adult T-cell leukemia lymphoma (ATLL). Material and methods: Diagnostic criteria included clinical features, cell morphology, immunophenotype, HTLV-I serology and/or DNA analysis by Southern blot or PCR. Results: According to the clinical presentation, 12 cases had the acute ATLL form, 6 had a lymphoma, 4 the chronic form and 4 had smoldering ATLL. The median presentation age was 50 years, younger than the Japanese patients, but significantly older than patients from other South American countries (eg Brasil, Jamaica, Colombia). The main clinical features: lymphadenopathy, skin lesions and hepatosplenomegaly, were similar in frequency to those of patients from other countries, except for the high incidence of associated neurological disease. Tropical Spastic Paraparesis (TSP) in our series of ATLL, was seen in one third of the patients (8/26). A T-cell immunophenotype was shown in all 26 cases and HTLV-I serology was positive in 25/26 patients. Molecular analysis on the seronegative patient showed clonal integration of proviral HTLV-I DNA into the lymphocytes DNA, and thus he may have been a poor responder to the retroviral infection. Proviral DNA integration was also demonstrated in 15/16 patients being clonal in 10, polyclonal in 3 (all smoldering cases) and oligoclonal in one. Conclusions: ATLL in Chile has similar clinical and laboratory features than the disease in other parts of the world, except for a younger age than Japanese patients but older than those from other Latin American countries and a high incidence of patients with associated TSP. Detailed morphological and immunophenotypic analysis of the abnormal circulating lymphocytes, together with the documentation of HTLV-I by serology and/or DNA analysis are key tests for the identification of this disease.
Leucemia linfoma T del adulto en Chile.: Estudio clínico-patológico y molecular de 26 pacientes
Cabrera C,M Elena; Labra G,Silvia; Meneses C,Pedro; Matutes,Estella; Cartier R,Luis; M Ford,Anthony; F Greaves,Melvyn;
Revista médica de Chile , 1999, DOI: 10.4067/S0034-98871999000800007
Abstract: background: adult t cell leukemia lymphoma is a lymphoproliferative syndrome etiologically associated to human t cell lymphotropic virus type i. aim: to describe the clinical and laboratory features of 26 caucasian chilean patients, with htlv-i positive adult t-cell leukemia lymphoma (atll). material and methods: diagnostic criteria included clinical features, cell morphology, immunophenotype, htlv-i serology and/or dna analysis by southern blot or pcr. results: according to the clinical presentation, 12 cases had the acute atll form, 6 had a lymphoma, 4 the chronic form and 4 had smoldering atll. the median presentation age was 50 years, younger than the japanese patients, but significantly older than patients from other south american countries (eg brasil, jamaica, colombia). the main clinical features: lymphadenopathy, skin lesions and hepatosplenomegaly, were similar in frequency to those of patients from other countries, except for the high incidence of associated neurological disease. tropical spastic paraparesis (tsp) in our series of atll, was seen in one third of the patients (8/26). a t-cell immunophenotype was shown in all 26 cases and htlv-i serology was positive in 25/26 patients. molecular analysis on the seronegative patient showed clonal integration of proviral htlv-i dna into the lymphocytes dna, and thus he may have been a poor responder to the retroviral infection. proviral dna integration was also demonstrated in 15/16 patients being clonal in 10, polyclonal in 3 (all smoldering cases) and oligoclonal in one. conclusions: atll in chile has similar clinical and laboratory features than the disease in other parts of the world, except for a younger age than japanese patients but older than those from other latin american countries and a high incidence of patients with associated tsp. detailed morphological and immunophenotypic analysis of the abnormal circulating lymphocytes, together with the documentation of htlv-i by serology and/or dna analysis
Síndromes linfoproliferativos crónicos en Chile: Estudio prospectivo de 132 casos
Cabrera C,María Elena; Marinov M,Neda; Guerra C,Carolina; Morilla,Ricardo; Matutes,Estella;
Revista médica de Chile , 2003, DOI: 10.4067/S0034-98872003000300007
Abstract: background: chronic lymphoproliferative disorders include a variety of diseases which are often a diagnostic problem for clinical hematologists. aim: to study prospectively the distribution and incidence of chronic lymphoproliferative disorders in chile and compare them with those of other western, latin american and oriental countries. patients and methods: a group of 132 patients were studied in a 36 months period (1999-2001), with a panel of monoclonal antibodies. a score for chronic lymphocytic leukemia was employed to differentiate it from other b-cell disorders. results: the median age was 63 years old (range 32-94). most patients had b-cell tumors (109) and the rest (23), t-cell tumors (82% vs 18%). forty five percent of patients with b-cell tumors had a chronic lymphocytic leukemia (cll), while the others were disseminated lymphomas. the incidence of t-cell tumors was slightly higher than that of other western countries. noteworthy is that the most common of these disorders was adult t cell leukemia/lymphoma (atll), in concordance with the high htlv-1 seroprevalence in chile. conclusions: a morphologic, immunophenotypic and pathological study in a large number of patients with chronic lymphoproliferative disorders in chile, shows a relatively low incidence of cll when compared to other chronic b-cell tumors and a high representation of atll associated to htlv-1 infection, compared with other western countries. the lower incidence of cll in our study might be due to patient's selection and/or underdiagnosis of this disease as a substantial proportion of cll are asymptomatic (rev méd chile 2003; 131: 291-8).
Efectos de la microestructura en las propiedades magnéticas de imanes híbridos de SrFe12O19/MQP-Q
Bueno Baqués, D.,Matutes Aquino, J. A.,Coral Flores, V.,Ayala Valenzuela, O.
Boletín de la Sociedad Espa?ola de Cerámica y Vidrio , 2005,
Abstract: Magnetic properties in Hybrid magnets, compression-molded consisting on mixtures of SrFe12O19 ferrite and MQP-Q (Nd2Fe14B + αFe) embedded in LLDPE were studied. Samples with the ratio %wt ferrite/%wt MQP-Q 4/82, 48/6 and 26/68 are compared to powders of pure starting magnetic materials. Microstructure was investigated by SEM and EDS. Magnetic interactions have been studied by isothermal remanence (IRM), dc-demagnetization remanence (DCD) curves. Hybrid samples show interactions initially positive, falling rapidly through zero, with a negative minimum, as the magnetic field increases. The effect of the microstructure in the ΔM curves is discussed. En este trabajo se estudiaron la microestructura y propiedades magnéticas de imanes híbridos moldeados por compresión, constituidos por mezclas de Ferrita de Estroncio (SrFe12O19) y MQP-Q (Nd2Fe14B + αFe) embebidas en una matriz de Polietileno Lineal de Baja Densidad (LLDPE). Se comparan las propiedades de las muestras con una relación % en peso de ferrita / % en peso de MQP-Q de 4/82, 48/6 y 26/68 con polvos de los materiales de partida. La microestructura se estudió por microscopía electrónica de barrido y microanálisis elemental. Las interacciones magnéticas fueron estudiadas por medio de curvas de desmagnetización isotérmica (IRM) y de desmagnetización DC (DCD). Se observan interacciones inicialmente positivas, que decrecen pasando por cero, con un mínimo negativo, a medida que se incrementa el campo magnético. Se discute el efecto de la microestructura en las curvas de ΔM.
Procesos de magnetización reversible-irreversible y propiedades de remanencia de ferrita de cobalto coprecipitada
Medina-Boudri, A.,Bueno-Baqués, D.,Matutes-Aquino, J.
Boletín de la Sociedad Espa?ola de Cerámica y Vidrio , 2001,
Abstract: Cobalt ferrite was obtained by coprecipitation of iron (II) sulphate and cobalt (II) sulphate in acetone medium. Using the moving Preisach model, the reversible (Mrev) and irreversible (Mirr) components of the magnetization were separated. The parameter η given by η= (dMrev / dMirr)Hi and the moving Preisach parameter km , were evaluated according to the relation η= kmχrev in order to investigate the behavior of Mrev. It was found that η is not proportional to the reversible susceptibility, therefore km is a function of the internal field. Isothermal remanent magnetization (IRM) and DC demagnetization (DCD) curves were measured . From these data the δm curve and the Henkel plot were obtained showing that all the points remain under the Wohlfath line indicating that the local disorder dominates (demagnetizing-like effect) over the mean-field effect. The switching field distribution curves were obtained by differentiation of the IRM and DCD curves. The peak values of these switching field distributions differ by a factor of 2.7. Se obtuvo ferrita de cobalto por coprecipitación de sulfatos de hierro y cobalto en acetona. Usando el modelo móvil de Preisach se separaron las componentes reversible (Mrev) e irreversible (Mirr) de la magnetización. El parámetro η definido como η= (dMrev / dMirr)Hi y el parámetro móvil de Preisach km , se evaluaron mediante la relación η= kmχrev para investigar el comportamiento de Mrev Se encontró que η no es proporcional a la susceptibilidad reversible, por lo tanto, km es una función del campo interno. Se midieron las curvas de magnetización isotérmica remanente (MIR) y de desmagnetización (DCD). A partir de los datos MIR y DCD se construyó la curva δm y el gráfico de Henkel, el cual se encuentra por debajo de la línea de Wohlfarth indicando que domina el desorden local (efecto del tipo desmagnetizante) sobre el efecto de campo medio. Diferenciando las curvas de MIR y DCD se obtuvieron las curvas de distribución de campos de conmutación. Los valores pico de estas distribuciones de campos de conmutación difieren por un factor de 2.7.
Procesos reversibles durante la inversión de la magnetización en la ferrita de cobalto
Medina-Boudri, A.,Cornejo, D. R.,Bertorello, H. R.,Matutes-Aquino, J.
Boletín de la Sociedad Espa?ola de Cerámica y Vidrio , 2002,
Abstract: A study of the magnetization reversal process at 300 K in a co-precipitated cobalt ferrite material was carried out. The evolution of the reversible Mrev and irreversible Mirr magnetization components were determined by measuring sets of recoil curves from different points on the initial magnetization curve and mayor demagnetization curve (Isothermal Remanent Magnetization and Direct Current Demagnetization Methods). The Mrev(Mirr)Hi curves at constant Hi < Hc , where Hc is the coercivity of the sample, exhibit a well-defined maximum (minimum) for the initial magnetization (demagnetization) process. This is characteristic of an increasing in the total domain wall area in the material during the processes of magnetization and demagnetization. This behavior for Mrev and the shape of the η= ( Mrev/ Mirr)Hi function, suggest that domain wall movement subject to pinning is the dominant mechanism for the reversal magnetization process in this material. Se realizó un estudio del proceso de inversión de la magnetización a 300 K en un material de ferrita de cobalto co-precipitada. La evolución de las componentes reversible Mrev e irreversible Mirr de la magnetización se determinó por el Método de Magnetización Isotérmica Remanente (MIR) que consiste en medir un conjunto de curvas de retorno a partir de diferentes puntos de la curva de magnetización inicial y por el Método de Desmagnetización de Corriente Directa (DCD) que consiste en medir un conjunto de curvas de retorno a partir de diferentes puntos de la curva mayor de desmagnetización. Estudios recientes han demostrado que existe una interrelación entre Mrev y Mirr expresada fenomenológicamente por la ecuación constitutiva dMrev= χ i rev dH+ηdMirr, donde χ i rev es la susceptibilidad intrínseca reversible, Hi es el campo interno y η(Hi,Hirr)= ( Mrev/ Mirr)Hi es la denominada función de interrelación. En esta ecuación constitutiva el primer término se encuentra asociado con la rotación reversible del vector de magnetización y el segundo término se debe a cambios en la cantidad y el movimiento de las paredes de dominio. En este trabajo se realizó una determinación experimental completa del comportamiento de Mrev(Hi,Mirr) y η(Hi,Mirr) Las curvas Mrev(Hi,Mirr) para Hi constante muestran un máximo bien definido (mínimo) para la curva de desmagnetización característico del movimiento de las paredes de dominio dentro de los granos del material. Por otro lado, el comportamiento experimental de R(Hi,Mirr) sugiere que el mecanismo dominante para la inversión de la magnetización en este material es el movimiento de las
In situ comparison of the critical current density in $Y Ba_2 Cu_3 O_{7-δ}$ thin films measured by the screening technique under two criteria
F. Gamboa,V. Sosa,I. Perez,J. A. Matutes-Aquino,A. Moewes
Physics , 2013, DOI: 10.1109/TASC.2014.2357758
Abstract: In this investigation we report the determination of the critical current density $J_c$ flowing in a $\mathrm{Y}\mathrm{Ba}_2\mathrm{Cu}_3\mathrm{O}_{7-\delta}$ superconducting thin film. Estimation of $J_c$ was carried out by an inductive technique, the so-called screening technique, in which both the imaginary part of the fundamental harmonic of susceptibility $\chi''_1$ and third harmonic voltage $V_3$ criteria were considered for the determination of the full penetration field. In order to verify the reliability of this technique under two criteria, we investigated the homogeneity of $J_c$ via transport measurements conducted on four microbridges patterned in the same film. Based on the transport method we found that both techniques yield similar results in the determination of $J_c$ for temperatures close to critical temperature $T_c$. However, at temperatures relatively far from $T_c$, the $V_3$ criterion showed a better agreement with the transport data. Furthermore, using both criteria, we propose a methodology to estimate in situ the coil factor associated with the $V_3$ criterion, avoiding in this way the need of implementing an additional technique.
Efecto de la adición de SiO2 sobre las propiedades magnéticas de ferritas de bario
Palomares-Sánchez, S.,Mirabal-García, M.,Matutes-Aquino, J. A.,Rosales, M. I.
Boletín de la Sociedad Espa?ola de Cerámica y Vidrio , 2000,
Abstract: The effect of SiO2 additions, from 0.2% to 10% in weight, on the magnetic and structural properties of barium ferrite, prepared by the chemical coprecipitation method, is reported. It was observed that the effect of silicon oxide on the ferrite is to drag the grain growth and to decompose the ferrite into hematite and, perhaps, a barium silicate. Se estudia el efecto de la influencia que tiene la adición de SiO2, en cantidades del 0.2% al 10% en peso, sobre las propiedades magnéticas y estructurales de las ferritas de bario preparadas por el método de coprecipitación química. Se observó que el efecto del óxido de silicio sobre la ferrita de bario fue el de actuar como inhibidor para el crecimiento del grano y el de descomponer la ferrita en hematita y, posiblemente, en un silicato de bario.
Efecto de la adición de Gd2O3 sobre las propiedades magnéticas de hexaferritas de estroncio
Castrezana-González, P.,Matutes-Aquino, J. A.,Rosales, M. I.,Sánchez Ll., J. L.
Boletín de la Sociedad Espa?ola de Cerámica y Vidrio , 1999,
Abstract: The hexaferrites (AFe12O19, A = Ba, Sr) have been used since years ago. Because of their low cost these materials continue in the market and they have not been substituted for other powerful magnets. The partial substitution of metallic elements or the use of additives in small proportions have been widely used for industrial processes in order to improve magnetic properties or the sintering process. Efforts had been made to determinate the effect of an important number of diamagnetic or paramagnetic cations on the microstructure and magnetic properties of the hexagonal ferrites. Previous studies have reported a remarkable increase in the coercitive field of the hexaferrites of barium with the substitution partial of that by La, Lu, Sm, Nd and Gd. In the present research a structural and magnetic study of sintered permanent magnets with the general formula Sr1-XGdX/2NaX/2Fe12O19 (0.00≤ X ≤0.10) was made. The samples were characterized by X-ray diffraction, vibrating sample magnetometry, scanning electron microscopy and elemental analysis (EDAX). The dependency of the densification, the medium grain size, the cells parameters and the magnetic properties with the gadolinium oxide content is discussed. Las hexaferritas (AFe12O19, A = Ba, Sr) se vienen utilizando desde hace varios a os; debido a su bajo costo dominan el mercado y no han sido sustituidas por imanes permanentes más potentes. La sustitución parcial de los elementos metálicos o la utilización de aditivos en peque a proporción ha sido ampliamente utilizada en la industria con el objeto de mejorar las propiedades magnéticas o facilitar el proceso de sinterización. Se han dedicado esfuerzos importantes para determinar el efecto de un número importante de iones diamagnéticos y paramagnéticos sobre la microestructura y las propiedades magnéticas de las ferritas hexagonales. Trabajos previos reportaron un aumento notable del campo coercitivo en hexaferritas de bario con substitución parcial de este elemento por La, Lu, Sm, Nd y Gd. En este trabajo se realiza un estudio estructural y magnético de imanes permanentes sinterizados con la fórmula general Sr(1-x)Gd x/2Na x/2Fe12O19 (0.00≤ X ≤0.10). Las muestras fueron caracterizadas por difracción de rayos X, magnetometría vibracional, microscopía electrónica de barrido y análisis elemental (EDAX). Se discute la dependencia de la densificación, el tama o de grano medio, los parámetros de celda y las propiedades magnéticas con el contenido de óxido de gadolinio.
Estudio comparativo de las propiedades magnéticas de ferritas hexagonales de Bario obtenidas por los métodos de coprecipitación y microemulsión
García-Casillas, P. E.,Matutes-Aquino, J. A.,Palla, B. J.,Shah, D. O.
Boletín de la Sociedad Espa?ola de Cerámica y Vidrio , 1999,
Abstract: Using the chemical coprecipitation method a precursor formed by iron and barium hidroxides and carbonates was obtained. For calcination temperatures higher than 730oC this precursor transforms into barium ferrite. Calcining the precursor during 2 hours a maximum magnetization of 59.1 emu/g for 925oC was obtained. Using the microemulsion method a fine precursor formed by iron and barium hidroxides and carbonates was obtained. For calcination temperatures higher than 760oC this precursor transforms into barium ferrite. Calcining the precursor during 12 hours a maximum magnetization of 60.5 emu/g for 925oC was obtained. For the barium ferrite obtained by microemulsion the intrinsic coercitivity was 20% lower than the intrinsic coercitivity of the barium ferrite obtained by chemical coprecipitation. This lower intrinsic coercivity should favor the microemulsion method for producing barium ferrite particles used as perpendicular magnetic recording medium. Por el método de coprecipitación química se obtuvo un precursor formado por hidróxidos y carbonatos de hierro y bario que al calcinarlo a temperaturas superiores a 730oC se transforma en ferrita de bario. Al calcinar el precursor durante 2 horas se obtuvo la magnetización máxima de 59.1 emu/g para la temperatura de 925oC. Por el método de microemulsión se obtuvo un precursor fino de hidróxidos y carbonatos de hierro y bario que al calcinarlo a temperaturas superiores a 760oC se transforma en ferrita de bario. Al calcinar el precursor durante 12 horas se obtuvo la magnetización máxima de 60.5 emu/g para la temperatura de 925oC. La coercitividad intrínseca del polvo de ferrita de bario obtenido por microemulsión resultó ser un 20% menor que la coercitividad intrínseca del polvo de ferrita de bario obtenido por coprecipitación. Esta menor coercitividad debe favorecer al método de microemulsión para la producción de partículas de ferrita de bario que sirvan como medio de grabación magnética perpendicular.
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