8,676 research outputs found
Polymeric foams as the matrix of voltammetric sensors for the detection of catechol, hydroquinone, and their mixtures
Producción CientíficaPorous electrodes based on polymethylmethacrylate and graphite foams (PMMA_G_F) have been developed and characterized. Such devices have been successfully used as voltammetric sensors to analyze catechol, hydroquinone, and their mixtures. The presence of pores induces important changes in the oxidation/reduction mechanism of catechol and hydroquinone with respect to the sensing properties observed in nonfoamed PMMA_graphite electrodes (PMMA_G). The electropolymerization processes of catechol or hydroquinone at the electrode surface observed using PMMA_G do not occur at the surface of the foamed PMM_G_F. In addition, the limits of detection observed in foamed electrodes are one order of magnitude lower than the observed in the nonfoamed electrodes. Moreover, foamed electrodes can be used to detect simultaneously both isomers and a remarkable increase in the electrocatalytic properties shown by the foamed samples, produces a decrease in the oxidation potential peak of catechol in presence of hydroquinone, from +0.7 V to +0.3 V. Peak currents increased linearly with concentration of catechol in presence of hydroquinone over the range of 0.37·10−3 M to 1.69·10−3 M with a limit of detection (LOD) of 0.27 mM. These effects demonstrate the advantages obtained by increasing the active surface by means of porous structures.Ministerio de Economía, Industria y Competitividad - Fondo Europeo de Desarrollo Regional (project AGL2015-67482-R)Junta de Castilla y Leon - Fondo Europeo de Desarrollo Regional (project VA-011U16
Multiple Paleozoic magmatic-orogenic events in the Central Extremadura batholith (Iberian Variscan belt, Spain)
Background The Central Extremadura batholith located in the southeast part of the Central Iberian Zone (e.g. Iberian
Autochthonous domain of the Iberian Variscan belt) was originally thought to have been generated entirely during Carboniferous
igneous activity. However, some recent geochronological work has shown the existence of Ordovician plutonic rocks.
Purpose The aim of this study is to re-examine the age of granitic rocks in the Central Extremadura batholith and complement
this information with new field and geochemical data. This data set is used: to constrain the relative timing of plutons
emplacement, as well as deformation and metamorphism preserved in the host rocks; to track deep crustal rocks and granitic
magma sources; and to discuss prevailing tectonic evolutionary models for the Paleozoic evolution of the Iberian Variscan
belt.
Methods We use geochemical and SHRIMP U-Pb zircon geochronology data of three granitic plutons (Ruanes, Plasenzuela
and Albalá) from the Central Extremadura batholith to track magmatic sources and provide a better understanding of temporal
and spatial relationships between deformation and magmatism in the Iberian Variscan belt.
Results Ruanes tonalite dated at 464 ± 2 Ma is peraluminous, magnesian and calc-alkaline, as typical of a magmatic arc
setting. We report, for the first time, the occurrence of a Middle Ordovician intrusion spatially and temporally related to host
deformed rocks of the Central Iberian Zone (e.g. the Iberian Autochthonous domain), which reached high-grade metamorphic
conditions. Plasenzuela two-mica leucogranite is strongly peraluminous and of anatectic origin and includes a Neoproterozoic
and Ordovician population of inherited zircon grains. This granite possibly derived from the partial melting of a crustal
source composed of Neoproterozoic metapelites and metagreywackes (Schist-Greywacke Complex) and/or Lower Ordovician
gneisses (Ollo de Sapo Formation), both including greywackes of volcano-sedimentary origin and peraluminous composition.
The crystallization age of 330 ± 7 Ma obtained for the syn-kinematic Plasenzuela two-mica leucogranite constrains the
functioning of D2 dextral strike-slip shear zones within the Iberian Autochthonous domain. The age of 309 ± 2 Ma obtained
for the Albalá cordierite-bearing monzogranite matches the age interval of the calc-alkaline magmatic suite post-dating the
main Variscan D1–D3 structures in the Iberian Autochthonous domain.
Conclusion The new data presented in this study make it possible to recognize multiple Paleozoic magmatic-orogenic events
(e.g. Caledonian, Variscan and Cimmerian) in the Central Extremadura batholith. During the Ordovician, the emplacement
of intermediate magmas at shallow depths gave rise to extensive metamorphism due to heat transfer to the host rocks. The
onset of this Ordovician plutonic–metamorphic complex in the Iberian Autochthonous domain is contemporaneous with
the development of an active continental margin probably related to the subduction of the Iapetus–Tornquist Ocean (i.e.
the Caledonian orogeny). During the Lower Carboniferous, these D2 strike-slip domains acted as lateral margins of largescale
gravitational collapses associated with the SE-direct transport of low-angle extensional shear zones (i.e. the Variscan
cycle). The emplacement of Upper Carboniferous arc type granitic rocks is interpreted in the context of the amalgamation
of Pangaea and the spatial proximity of Iberia relative to the Eurasian active margin in the course of Paleotethys subduction
(i.e. the Cimmerian orogeny)
DISTRIBUTION OF PIGMENT CELLS IN THE HEART OF THE RABBITFISH, CHIMAERA MONSTROSA (CONDRICHTHYES: HOLOCEPHALI)
El resumen aparece en el Program & Abstracts of the 10th International Congress of Vertebrate Morphology, Barcelona 2013. Anatomical Record, Volume 296, Special Feature — 1: P-076.The study of extracutaneous cells producing and storing melanin is of interest because it
may provide valuable information about the presence of neural crest elements in internal
organs and tissues. Here we report, for the first time, the presence and distribution of
melanophores in the heart of a chondrichthyan species, the rabbitfish, Chimaera
monstrosa. Pigment cells were found in all of 20 hearts examined. Pigment cells occur
mainly in the cardiac outflow tract, which consists of two anatomical components, the
proximal, myocardial conus arteriosus and the distal, non-myocardial bulbus arteriosus.
A few groups of dark pigmented cells were found in the apex of the ventricle of one
specimen and in the atrium of two specimens. In all instances, the melanophores were
located in the subepicardial space, where they could be well recognized in both
unstained and stained histological sections. The distribution and intensity of the
pigmentation in the cardiac outflow tract varies markedly between individuals. In all
cases, however, the pigmented area is larger on the dorsal than on the ventral surface.
Dorsally, the size of the pigmented area ranges from a fringe that includes the bulbus
and the distal part of the conus to the whole surface of the outflow tract. Ventrally, the
pigmented area does not cover the entire conus arteriosus. The intensity of the
pigmentation also varies widely; in general, it is highest at the distal portion of the conus.
There is no relationship between the distribution and intensity of the pigmentation and
the sex and age of the animals. The functional role of the pigmented cells is unknown. If
the melanophores in the heart of C. monstrosa are indeed of neural crest origin, it would
suggest a notable contribution of the neural crest cells to the cardiac outflow tract in
holocephalans.Proyecto CGL2010-16417/BOS; Fondos FEDER
BES-2011-04690
MYOCARDIAL STRUCTURE AND VASCULARIZATION OF THE HEART VENTRICLE IN HOLOCEPHALI: IMPLICATIONS FOR HEART EVOLUTION
El resumen aparece en el Program & Abstracts of the 10th International Congress of Vertebrate Morphology, Barcelona 2013. Anatomical Record, Volume 296, Special Feature — 1: P-075.It has been classically assumed that the ventricle of the primitive vertebrate heart is
composed of spongy myocardium, supplied exclusively by oxygen-poor, luminal blood.
This idea is on two facts: (1) extant agnathans have a spongy ventricular myocardium,
and (2) in avian and mammalian embryos, the formation of trabeculated myocardium
precedes the appearance of compact myocardium. Recently, it has been proposed that,
like elasmobranchs, the early gnathostomes possess a fully vascularised ventricle
composed of mixed myocardium. We tested this idea by studying the structure and
vascularisation of the ventricular myocardium in four holocephalan species of the
families Chimaeridae and Rhinochimaeridae. Chimaera monstrosa, Hidrolagus affinis
and Harriotta raleighana have a spongy myocardium covered by a thin layer of cardiac
muscle. In H. raleighana, the compacta is reduced to an extremely fine rim. In all three
species there is a well-developed coronary artery system consisting of subepicardial
vessels which give off branches that penetrate the myocardial trabeculae.
Rhinochimaera atlantica has no compacta and its ventricular coronary artery system is
reduced to subepicardial vessels that do not enter the spongy layer. This report is the
first to show that in wild living vertebrates, a coronary artery system supplying the whole
myocardium exists in the absence of a well-developed compacta, which supports
experimental work that shows that myocardial cell proliferation and coronary vascular
growth rely on genetically separated programs. We conclude that the mixed ventricular
myocardium is primitive for chondrichthyans, and that the lack of compacta in some
holocephalans is a derived character. Moreover our results support the hypotheses that
the mixed myocardium is the primitive condition in gnathostomes, and that the absence
of a compacta in different actinopterygian taxa is the result of its repeated loss during
evolution.Proyecto CGL2010-16417/BOS; Fondos FEDE
Luces y sombras del análisis de expresión génica utilizando microarrays. Un ejemplo en cerdo ibérico
Ponencia publicada en ITEA, vol.104La tecnología de los microarrays de expresión es la herramienta ideal para el estudio de patrones de expresión de miles de genes de forma simultánea. Sin embargo existe gran variabilidad de resultados atribuible a los aspectos técnicos y de análisis estadístico. En este trabajo presentamos algunos de los problemas surgidos en el estudio de las diferencias de expresión en hígado de cerdos ibéricos para los tratamientos sexo y alimentación empleando microarrays de Affymetrix. Los datos de expresión normalizados fueron analizados siguiendo dos aproximaciones de la metodología de los modelos mixtos. Para ambos tratamientos las diferencias de expresión detectadas fueron dependientes del modelo de análisis y solo un pequeño número de genes diferencialmente expresados fueron coincidentes en ambas estrategias estadísticas. Algunas de estas diferencias de expresión fueron validadas por PCR cuantitativa. Además identificamos errores de diseño y falta de anotación de las sondas del array. Los resultados de este estudio nos han permitido detectar diferencias de expresión de algunos genes de interés, pero también remarcan la necesidad de realizar estudios complementarios que confirmen las diferencias de expresión reveladas a través de la tecnología de los microarraysLights and darkness of gene expression analysis using microarrays: an example in Iberian pigs Expression microarray technology is the ideal tool for the study of thousands of gene expression patterns simultaneously. However there is a great variability of results attributed to technical and statistical analysis aspects. In this work we present several of the arisen problems of a differential expression study in liver of Iberian pigs under the treatments sex and feeding level using Affymetrix microarray. Normalized expression data were analyzed following two approaches of the mixed model methodology. In both treatments the detected differential expressions were dependent of the statistical model and just a small number of genes were coincident between both statistical strategies. Some of the expression differences were confirmed by quantitative PCR. Besides, we have identified design mistakes and missing annotation of the array probes. The results of this study have allowed us to detect differential expression of interesting genes, but it pointed out the necessity of carrying out complementary studies in order to confirm the differential expressions revealed using microarrays technology
Estudio morfofuncional de la marcha humana
Se ha estudiado la marcha con dos plataformas de fuerzas (dinamométricas) en 60 sujetos, 30 varones y 30 mujeres, sin patología aparente del aparato locomotor,con edades comprendidas entre 17 y 22 años.
Presentamos los resultados obtenidos y establecemos a partir de los mismos, los valores medios normales de
los parámetros más significativos de la marcha.
Con el fin de observar la existencia o no de una relación entre la morfología y las variables estudiadas en la marcha, se correlacionaron las magnitudes y los tiempos de las fuerzas desarrolladas en los tres ejes del espacio, con diversos parámetros antropométricos.
Los parámetros antropométricos que mayor correlación presentaron con los parámetros de marcha (p 0,001) fueron el diámetro biacromial, el ancho maleolar dcho. con apoyo, y el ancho maleolar izquierdo.Peer Reviewe
Alargamiento en agenesia de tibia y peroné
Las displasias o defectos congénitos (parciales
o totales) de la pierna pueden a fin didáctico
subdividirse en deficiencia congénita de la tibia
y en deficiencia congénita del peroné.
Los miembros inferiores se originan de la
llamada "yema de extremidades" provenientes
del mesenquima y apareciendo al final de la
cuarta semana, y están opuestas a los segmentos
lumbares extendiéndose ventralmente. Los
centros primarios de osificación de las diafisis
de los huesos aparecen entre las 7 y 12 semanas.
Las epífisis aparecen por centros secundarios,
siendo los primeros en aparecer aquellos
alrededor de la rodilla -distal de fémur y proximal
de tibia- al noveno mes. Los músculos se
desarrrollan in situ alrededor de los huesos en
formación. A la séptima semana existe una rotación
de los brazos y piernas, que en las extremidades
inferiores rotan medialmente 90° (rodilla
hacia adelante) de forma que los músculos
externos se colocan hacia adelante. De alli que
al haber una interrupción del proceso normal
de evolución y rotación la patología congénita
de miembros inferiores afecte mayormente las
estructuras externas
- …