Precipitados no cristalinos de hierro en sistemas naturales de Galicia

[Resumen] Se estudian tres precipitados ferruginosos, de diferentes localidades de Galicia, mediante el empleo de diversas técnicas ihstrumentales ( DRX, SI~,ATD, etc.), de disolución selectiva y caracterización de sus propiedades físico-químicas. Los precipitados están constituidos por compuestos de hierro, con un contenido aproximado del 50% de ~Fe20~ que es soluble en oxalato en un 90 - 96 %y cantidades importantes de materia orgánica o sílice según los casos. Sus características de difracción de rayos X, espectros IR y curvas de ATD son pr6ximos a los de materiales descritos como ferrihidritas de muy baja cristalinidad ( protoferrihidrita ). Además de la juventud de los precipitados los efectos de materia orgánica y sílice parecen ser los responsables de su escaso grado de orden.[Abstract] Three ferruginous precipitates of different localities of Galicia are studied using instrumental (XRD, IRS,DTA, etc. ) and selective dissolution techniques, and typifying their physico-chemical properties. the precipitates are rich in Fe 20 3 ( about_, 50%), that is almost completely oxalate soluble (9::16%) 11 and in organic matter or silica. Their characteristics (XRD,IRS and DTA ) resemble closely toe ones of materials described as ferrihydrites of very low crystallinity (protoferrihydri te). Besides the shortage of the precipitates, the effects of organic matter and silica seem to be the responsibles fo rtheir low orde

Componentes no cristalinos y cristalinos (gibbsita y caolinita) en los productos de neoformación de rocas graníticas de Galicia.

[Resumen] El estudio de los recubrimientos y costras existentes en las diaclasas y fracturas superficiales de rocas graníticas de Galicia permite la diferenciación de dos tipos de materiales: a) Materiales con predominio de componentes con bajo grado de orden. Se localizan en las fracturas subhorizontales por las que discurre el agua que atraviesa el suelo y la saprolita. b) Materiales cristalinos de naturaleza gibbsítica y/o caolinítica. Se localizan en las fracturas verticales.[Abstract] The study of 'coatings and crust on the diaclasas and cracks on the surface of granitic rocks in Galicia, let us differenciate two kinds of materials. a) Materials in wich low order degree components are predominant. These are lacated in subhorizontal cracks through wich water flows. b) Crystalline materials with a gibbsitic and/or kaolinitic minerals, located in the vertical crack

LPS-Induced Genes in Intestinal Tissue of the Sea Cucumber Holothuria glaberrima

Metazoan immunity is mainly associated with specialized cells that are directly involved with the immune response. Nevertheless, both in vertebrates and invertebrates other organs might respond to immune activation and participate either directly or indirectly in the ongoing immune process. However, most of what is known about invertebrate immunity has been restricted to immune effector cells and little information is available on the immune responses of other tissues or organs. We now focus on the immune reactions of the intestinal tissue of an echinoderm. Our study employs a non-conventional model, the echinoderm Holothuria glaberrima, to identify intestinal molecules expressed after an immune challenge presented by an intra-coelomic injection of lipopolysaccharides (LPS). The expression profiles of intestinal genes expressed differentially between LPS-injected animals and control sea water-injected animals were determined using a custom-made Agilent microarray with 7209 sea cucumber intestinal ESTs. Fifty (50) unique sequences were found to be differentially expressed in the intestine of LPS-treated sea cucumbers. Seven (7) of these sequences represented homologues of known proteins, while the remaining (43) had no significant similarity with any protein, EST or RNA database. The known sequences corresponded to cytoskeletal proteins (Actin and alpha-actinin), metabolic enzymes (GAPDH, Ahcy and Gnmt), metal ion transport/metabolism (major yolk protein) and defense/recognition (fibrinogen-like protein). The expression pattern of 11 genes was validated using semi-quantitative RT-PCR. Nine of these corroborated the microarray results and the remaining two showed a similar trend but without statistical significance. Our results show some of the molecular events by which the holothurian intestine responds to an immune challenge and provide important information to the study of the evolution of the immune response

Degeneracy in excited state quantum phase transitions of two-level bosonic models and its influence on system dynamics

Excited state quantum phase transitions in collective many-body quantum systems influence the system spectral properties due to changing degeneracy patterns in different phases. We report a fundamental difference in the nature of the degeneracy for boson two-level models, depending on the dimension of the space where the models were defined. To illustrate the consequences, we assess the validity of an out-of-time-order correlator as a possible order operator for excited state quantum phase transitions in different models

Desarrollo de habilidades y construcción conceptual : una secuencia sobre flotación en educación básica

Se presenta una secuencia para enseñar nociones sobre flotabilidad en un grupo de estudiantes de educación primaria. Su objetivo es brindar a los alumnos elementos que les ayuden a desarrollar nociones sobre el proceso de flotación, identificando algunas de las variables implicadas, como el volumen y la masa, a la par de promover el desarrollo de habilidades para el razonamiento científico, en este caso las que les permitan identificar y recolectar datos, elaborar predicciones, probar ideas, predicciones o explicaciones, identificar patrones y relaciones y sugerir posibles explicaciones. La secuencia, que forma parte de las actividades diseñadas para el Programa Adopte un Talento (PAUTA), ha sido probada en 6 grupos de estudiantes y los resultados de la evaluación se encuentran en proceso de análisis