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Search Results: 1 - 10 of 46512 matches for " Cruz-Ramírez "
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Dise o de polvos de molde para colada continua de slabs de aceros bajo carbono
Cruz-Ramírez, A.,Chávez-Alcalá, J. F.,Romero-Serrano, J. A.
Revista de Metalurgia , 2004,
Abstract: Commercial fluxes were characterized by laboratory tests, and their original properties were changed with additions of chemical reagents in order to establish criteria and design strategies to produce new fluxes. The characterization of the commercial fluxes reveals that they are produced by simple mechanical blend of minerals, using feldspars and clays as base materials, containing SiO2, Al2O3, Na2 O and in less quantity K2O, MgO, Fe2 O3and MnO; limestone as the main source of CaO, fluorspar (CaF2) used to control the viscosity and graphite as carbon source. Melting-solidification tests revealed melting and fluidity temperatures and the existence of abundant mineralogical phases formed during the flux solidification. Some important mineralogical compounds are the nepheline (NaAlSiO4) and cuspidine (Ca4Si2O7F2); these species have a direct influence on the heat transfer phenomena from strand to mold and therefore on the phase transformations and the shrinkage of the steel. A partir de la caracterización de polvos comerciales mediante pruebas de laboratorio y la modificación de sus propiedades mediante adiciones de compuestos químicos, se identificaron y desarrollaron criterios y estrategias de dise o que sirvieron de base para elaborar nuevos polvos. La caracterización de los polvos comerciales indica que se fabrican por simple mezcla mecánica de minerales, utilizando feldespatos y arcillas como materiales base, que contienen SiO2, Al2O3, Na2 O y, en menor proporción, K 2O, MgO, Fe2 O3 y MnO, caliza como fuente principal de CaO, fluorita (CaF2) como fluidificante y grafito como fuente de carbono. Mediante pruebas de fusión-solidificación se determinaron las temperaturas de fusión y fluidez de los polvos y se identificó una gran variedad de especies cristalinas que se forman durante la solidificación, entre las que destacan la nefelina (NaAlSiO4) y la cuspidina (Ca4Si2O7F2), que tienen una influencia directa sobre los fenómenos de transferencia de calor de la línea al molde y, por lo tanto, en la velocidad de transformación de fases y de contracción del acero.
Estudio termodinámico del sistema SiO2-NiO-Cu2O
Cruz-Ramírez,Antonio Romero-Serrano,Federico Chávez-Alcalá,Marissa Vargas-Ramírez
Revista Latinoamericana de Metalurgia y Materiales , 2010,
Abstract: En el presente trabajo, se llevó a cabo una evaluación de las propiedades termodinámicas y diagramas de fase de los sistemas NiO-SiO2, Cu2O-SiO2 y SiO2- NiO-Cu2O mediante la aplicación del modelo estructural de escorias para la fase líquida. Este modelo termodinámico considera que cada óxido metálico produce una reacción de depolimerización de la red de SiO2 involucrando un cambio en la energía libre de Gibbs del sistema. Un programa que lleva a cabo una optimización por mínimos cuadrados, permite que todos los datos termodinámicos y diagramas de fases sean optimizados simultáneamente para los sistemas binarios. De esta forma, los datos de estos sistemas binarios han sido analizados y representados con un número peque o de parámetros de ajuste. El modelo estructural para sistemas binarios se extrapoló para sistemas ternarios considerando una mezcla aleatoria de cationes Cu+ y Ni2+, debido a que los sistemas binarios Cu2OSiO2 y NiO-SiO2 presentan comportamientos termodinámicos distintos, el sistema ternario SiO2- NiO-Cu2O se propone como diagrama de fase tentativo. In this work, the evaluation of the thermodynamic properties and phase diagrams of the NiO-SiO2, Cu2O-SiO2 and SiO2- NiO-Cu2O systems is presented in which a structural model is used for the liquid phase. This thermodynamic model is based on the assumption that each metallic oxide produces the depolymerization reaction of silica network with a characteristic Gibbs free energy change. A least squares optimization program permits all available thermodynamic and phase diagram data to be optimized simultaneously for the binary systems. In this manner, data for these binary systems have been analyzed and represented with a small number of parameters. The binary structural model is extended to the ternary system assuming a random mixing of cations Cu+ and Ni2+, since the Cu2O-SiO2 and NiO-SiO2 binary systems exhibit dissimilar thermodynamic behavior, the SiO2- NiO-Cu2O ternary system is proposed as a tentative phase diagram.
Functional and Transcriptome Analysis Reveals an Acclimatization Strategy for Abiotic Stress Tolerance Mediated by Arabidopsis NF-YA Family Members
Marco Antonio Leyva-González, Enrique Ibarra-Laclette, Alfredo Cruz-Ramírez, Luis Herrera-Estrella
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0048138
Abstract: Nuclear Factor Y (NF-Y) is a heterotrimeric complex formed by NF-YA/NF-YB/NF-YC subunits that binds to the CCAAT-box in eukaryotic promoters. In contrast to other organisms, in which a single gene encodes each subunit, in plants gene families of over 10 members encode each of the subunits. Here we report that five members of the Arabidopsis thaliana NF-YA family are strongly induced by several stress conditions via transcriptional and miR169-related post-transcriptional mechanisms. Overexpression of NF-YA2, 7 and 10 resulted in dwarf late-senescent plants with enhanced tolerance to several types of abiotic stress. These phenotypes are related to alterations in sucrose/starch balance and cell elongation observed in NF-YA overexpressing plants. The use of transcriptomic analysis of transgenic plants that express miR169-resistant versions of NF-YA2, 3, 7, and 10 under an estradiol inducible system, as well as a dominant-repressor version of NF-YA2 revealed a set of genes, whose promoters are enriched in NF-Y binding sites (CCAAT-box) and that may be directly regulated by the NF-Y complex. This analysis also suggests that NF-YAs could participate in modulating gene regulation through positive and negative mechanisms. We propose a model in which the increase in NF-YA transcript levels in response to abiotic stress is part of an adaptive response to adverse environmental conditions in which a reduction in plant growth rate plays a key role.
Pseudomembranous colitis and bacteremia in an immunocompetent patient associated with a rare specie of Clostridium (C. ramosum) Colitis pseudomembranosa y bacteriemia en paciente inmunocompetente asociadas a una rara especie de Clostridium (C. ramosum)
Alfonso Alcalde-Vargas,Claudio Trigo-Salado,Eduardo Leo-Carnerero,Dolores de-la Cruz-Ramírez
Revista Espa?ola de Enfermedades Digestivas , 2012,
Multinational Measles Outbreak in Post-Elimination Era, Involves Three Countries of North America and a European Country in a Short Transmission Chain  [PDF]
Cuitláhuac Ruiz-Matus, Lorena Suárez-Idueta, Ilse Herbas-Rocha, José Luis Diaz-Ortega, Edith Cruz-Ramírez, Abraham Ramírez-Jurado, Irma López-Martínez, José Cruz Rodríguez-Martínez, José Alberto Díaz-Qui?onez
World Journal of Vaccines (WJV) , 2015, DOI: 10.4236/wjv.2015.52010
Abstract: Background: Four measles cases in Canada and one in the United States are linked to international importation of measles in Playa del Carmen, Quintana Roo, Mexico. Objective: To describe characteristics of transmission and not spillover to local population in Mexico. Material and Methods: The outbreak investigation was based on active search of cases and in the rapid monitoring of vaccination coverage in children aged 1 - 7 years old. Laboratory confirmation by Enzyme-Linked Immunosorbent Assay (ELISA) and molecular detection by Reverse Transcriptase-Polymerase Chain Reaction (RT-PCR) assay in throat swab and urine were done. Results: One transmission chain with three generations of cases was identified. The primary case was a 9-year-old boy who was infected in Wales, UK. His sisters aged 7 and 15 years old respectively, were the first generation of cases in Mexico. The second generation was related to the imported cases, and affected two Canadian tourists and an American woman aged 39 years old. A third generation occurred in Canada and affected an infant of 15 months of age and his sister aged 4 years old. The genotype D8 which was circulating in UK was identified in these patients. One probable case was detected in Quintana Roo, but was discarded by laboratory testing. The coverage with at least one dose of Measles-Mumps-Rubella (MMR) vaccine ranged from 95% to 99.5%. Conclusion: International travelers with no history of vaccination are at risk of acquiring measles even in countries that have interrupted endemic transmission. The high immunization coverage of measles containing vaccine could explain the absence of cases in Mexican population. Highlights: Multinational measles outbreak in a country without endemic transmission. The findings exhibit the importance of immunization in international travelers in the post-elimination era.
Mold flux characterization for thin slab casting of steel
Cruz-Ramírez, A.,Vargas-Ramírez, M.,Hernández-Pérez, M. A.,Palacios-Beas, E.
Revista de Metalurgia , 2012,
Abstract: The mineralogical constitution and the melting-solidification behavior of two commercial fluxes for thin slab casting of steel were determined. The characterization of the commercial fluxes as received show the presence of wollastonite (CaO. SiO2), a sodium carbonate (Na2CO3), calcite (CaCO3), fluorite (CaF2) and carbon as the main components by X ray powder diffraction (XRD) and microscopic techniques. When fluxes were heated to 1573 K and further solidification, there was almost a whole transformation from the original compounds to cuspidine (3CaO - 2SiO2 - CaF2) and nepheline (Na2O - Al2O3 - 2SiO2) phases. The thermal gravimetrical analysis showed an important weight reduction in both fluxes due to the thermal decompositions of calcite and sodium carbonate. The characterization reveals that fluxes are produced by an agglomeration process. Se determinó la composición mineralógica y el comportamiento de fusión-solidificación de dos fundentes comerciales para la colada de planchón delgado de acero. La caracterización de los fundentes comerciales por difracción de rayos X (XRD) y técnicas de microscopía muestra la presencia de wollastonita (CaO - SiO2), un carbonato de sodio (Na2CO3), calcita (CaCO3), fluorita (CaF2) y carbono como los principales componentes. Cuando los fundentes se calentaron a 1.573 K y después de la solidificación, hubo una transformación casi total de los compuestos originales a las fases cuspidina (3CaO - 2SiO2 - CaF2) y nefelina (Na2O - Al2O3 - 2SiO2). El análisis termogravimétrico muestra una importante reducción de peso en los fundentes debido a la descomposición térmica de la calcita y el carbonato de sodio. La caracterización indica que los fundentes son producidos por un proceso de aglomeración.
Cierre percutáneo del conducto arterioso persistente con dispositivo Amplatzer en ni?os: resultados inmediatos y a un a?o
Parra-Bravo, J Rafael;Cruz-Ramírez, Arturo;Toxqui-Terán, Alejandra;Juan-Martínez, Enriqueta;Chávez-Fernández, Alejandro;Lazo-Cárdenas, César;Beirana-Palencia, Luisa;Estrada-Flores, José;
Archivos de cardiología de México , 2009,
Abstract: objective: percutaneous closure of patent ductus arteriosus (pda) is a well established technique. our objective was to determine the safety and efficacy of the amplatzer occluder for the treatment of pda in children. methods: from november 2005 to june 2007 we reviewed the clinical records of 39 patients (23 girls and 16 boys), with a mean age of 19.8 ± 13.7 months and weight 9.2 ± 3.2 kg, who underwent percutaneous closure of a pda with an amplatzer device. the forty one percent of the patients (16/39) were < 1 year of age, and 71.8 % (28/39) weighed < 10 kg. the age of children with body weight < 10 kg was 13.1 ±6.1 months (range 5-33 months). the morphology of the pda was determined by a lateral aortogram and classified according to krichenko. all the patients were followed-up with radiologic and echocardiographic control at 24 hours, 1, 3, 6 and 12 months postinsertion (median 20 months). results: the pda diameter ranged between 2.0 mm to 12 mm (3.6 mm ± 2.0 mm) in the 39 patients included. pda types according to krichenko were: type a = 25 (64.1%), type b = 1 (2.6%), type c = 5 (12.8%), type d = 2 (5.1%) and type e = 3 (7.7%). three patients had a residual pda post-surgical closure attempt. qp/qs ratio was 2.4 ± 1.5 (range 1.0-6.7) and the relation psp/pss was 0.49 ± 0.18 (range: 0.21-0.87). pulmonary hypertension was present in 16 patients (41%). the amplatzer occluder was implanted successfully in 36/39 patients (92.3%). the procedure failed in three cases: 1) difficulty to place the device due to wrong assessment of the ductus size; 2) difficulty to advance the device due to angulation (kinking) of the releasing system; 3) migration of the device to descending aorta. the mean time of fluoroscopy and for the entire procedure was 13.2 ± 6.3 minutes and 65.3 ± 21.9 minutes, respectively. there were no deaths with the procedure. minor and mayor complications occurred in eight patients, all of them but one, in children with body weight < 10 kg. in the 36 success
Bioactive Lipidic Extracts from Octopus (Paraoctopus limaculatus): Antimutagenicity and Antiproliferative Studies
Carolina Moreno-Félix,Griselda Wilson-Sánchez,Susana-Gabriela Cruz-Ramírez,Carlos Velázquez-Contreras
Evidence-Based Complementary and Alternative Medicine , 2013, DOI: 10.1155/2013/273582
A SCARECROW-RETINOBLASTOMA Protein Network Controls Protective Quiescence in the Arabidopsis Root Stem Cell Organizer
Alfredo Cruz-Ramírez equal contributor,Sara Díaz-Trivi?o equal contributor,Guy Wachsman ?,Yujuan Du ?,Mario Arteága-Vázquez,Hongtao Zhang,Rene Benjamins,Ikram Blilou,Anne B. Neef,Vicki Chandler,Ben Scheres
PLOS Biology , 2013, DOI: 10.1371/journal.pbio.1001724
Abstract: Quiescent long-term somatic stem cells reside in plant and animal stem cell niches. Within the Arabidopsis root stem cell population, the Quiescent Centre (QC), which contains slowly dividing cells, maintains surrounding short-term stem cells and may act as a long-term reservoir for stem cells. The RETINOBLASTOMA-RELATED (RBR) protein cell-autonomously reinforces mitotic quiescence in the QC. RBR interacts with the stem cell transcription factor SCARECROW (SCR) through an LxCxE motif. Disruption of this interaction by point mutation in SCR or RBR promotes asymmetric divisions in the QC that renew short-term stem cells. Analysis of the in vivo role of quiescence in the root stem cell niche reveals that slow cycling within the QC is not needed for structural integrity of the niche but allows the growing root to cope with DNA damage.
Pharmacokinetic and pharmacodynamic characterization of a new formulation containing synergistic proportions of interferons alpha-2b and gamma (HeberPAG(R)) in patients with mycosis fungoides: an open-label trial
Yanelda García-Vega, Idrian García-García, Sonia E Collazo-Caballero, Egla E Santely-Pravia, Alieski Cruz-Ramírez, ángela D Tuero-Iglesias, Cristian Alfonso-Alvarado, Mileidys Cabrera-Placeres, Nailet Castro-Basart, Yaquelín Duncan-Roberts, Tania I Carballo-Treto, Josanne Soto-Matos, Yoandy Izquierdo-Toledo, Dania Vázquez-Blomquist, Elizeth García-Iglesias, Iraldo Bello-Rivero
BMC Pharmacology and Toxicology , 2012, DOI: 10.1186/2050-6511-13-20
Abstract: An exploratory, prospective, open-label clinical trial was conducted. Twelve patients, both genders, 18 to 75 years-old, with mycosis fungoides at stages IB to III, were eligible for the study. All of them received intramuscularly a single high dose (23 x 106 IU) of a novel synergistic IFN mixture (HeberPAG(R)) for pharmacokinetic and pharmacodynamic studies. Serum IFN alpha-2b and IFN gamma concentrations were measured during 96 hours by commercial enzyme immunoassays (EIA) specific for each IFN. Other blood IFN-inducible markers and laboratory variables were used as pharmacodynamics and safety criteria.The pharmacokinetic evaluation by EIA yielded a similar pattern for both IFNs that are also in agreement with the well-known described profiles for these molecules when these are administered separately. The average values for main parameters were: Cmax: 263 and 9.3 pg/mL; Tmax: 9.5 and 6.9 h; AUC: 4483 and 87.5 pg.h/mL, half-life (t1/2): 4.9 and 13.4 h; mean residence time (MRT): 13.9 and 13.5 h, for serum IFN alpha-2b and IFN gamma, respectively. The pharmacodynamic variables were strongly stimulated by simultaneous administration of both IFNs: serum neopterin and beta-2 microglobulin levels (beta2M), and stimulation of 2'-5' oligoadenylate synthetase (OAS1) mRNA expression. The most encouraging data was the high increment of serum neopterin, 8.0 ng/mL at 48 h, not been described before for any unmodified or pegylated IFN. Additionally, beta2M concentration doubled the pre-dose value at 24--48 hours. For both variables the values remained clearly upper baseline levels at 96 hours.HeberPAG(R) possesses improved pharmacodynamic properties that may be very useful in the oncologic setting. Efficacy trials can be carried out to confirm these findings.Trial registration: Registro Publico Cubano de Ensayos Clinicos RPCEC00000130.
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