987 research outputs found
Influencia de la adición de estaño en el proceso de precipitación en una aleación de Cu-Ni-Zn
ABSTRACT: Influence of tin additions on the precipitation processes in a Cu-Ni-Zn alloys. The influence of
1.1 wt% tin additions on the precipitation hardening of Cu-11 wt% Ni-20 wt% Zn alloy was studied by
Differential Scanning Calorimetry (DSC), microhardeness measurements and High Resolution Transmission
Electron Microscopy (HRTEM). The calorimetric curves, in the range of temperatures analyzed, show the presence
of two exothermic reactions in the ternary alloy, associated to the short-range-order development assisted
by migration of excess vacancies. On the other hand, one exothermic and one endothermic reaction are observed
in the quaternary alloy, associated to the formation and dissolution of Cu2NiZn precipitates, respectively. It has
been show that an addition of 1.1% tin plays an important role in the formation of Cu2NiZn precipitates,
responsible for the precipitation hardening of the ternary alloy.Peer Reviewe
CRUZ CRUZ, J., Sentido del curso histórico. Lecciones de Filosofía de la Historia, Pamplona, 1988, 414 págs. [RECENSIÓN]
Loquat Fruit Lacks a Ripening-Associated Autocatalytic Rise in Ethylene Production
[EN] Loquat is considered as a non-climacteric fruit; however, there is an evidence of a climacteric-like maturation. Therefore, it seems its ripening behavior has yet to be satisfactory classified. Because autocatalytic regulation of ethylene production during fruit ripening is one of the primary features defining climacteric-like fruit maturation, we examined its ability of autocatalysis during ripening by applying the ethylene-releasing compound ethephon to the on-tree-fruit or ethylene to detached fruit of 'Algerie' loquat and measuring its ethylene and CO2 production. We also analyzed indoleacetic acid (IAA), gibberellin, cytokinin, and abscisic acid (ABA) contents as plant hormones involved in fruit ripening. The fruit response to ethephon (500 mg l(-1)) applied at color change was immediate producing increasing amounts of ethylene during the 4 h following the treatment, but 24 h after treatment onward values were similar to those produced by untreated fruit. Similar results were obtained when applying ethylene to detached fruit (10 mu l l(-1)). Accordingly, applying ethephon (200 mg l(-1)) did not advance harvest; neither the color nor the percentage of fruit harvested at the first picking date differed significantly from the untreated fruit. Flesh firmness, total soluble solid concentration, and acidity of juice were not significantly altered either. IAA concentration reached the maximum value when fruit stopped growing, declining sharply at fruit color change; active gibberellins and cytokinins declined continuously during the fruit growth period, and ABA content sharply increased during ripening, peaking after fruit color break. 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Ethylene biosynthesis and perception during ripening of loquat fruit (Eriobotrya japonica Lindl.)
[EN] In order to gain insights into the controversial ripening behavior of loquat fruits, in the present study we have analyzed the expression of three genes related to ethylene biosynthesis (ACS1, ACO1 and ACO2), two ethylene receptors (ERS1a and ERS1b), one signal transduction component (CTR1) and one transcription factor (EIL1) in peel and pulp of loquat fruit during natural ripening and also in fruits treated with ethylene (10 mu LL-1) and 1-MCP (10 mu LL-1), an ethylene action inhibitor. In fruits attached to or detached from the tree, a slight increase in ethylene production was detected at the yellow stage, but the respiration rate declined progressively during ripening. Accumulation of transcripts of ethylene biosynthetic genes did not correlate with changes in ethylene production, since the maximum accumulation of ACS1 and ACO1 mRNA was detected in fully coloured fruits. Expression of ethylene receptor and signaling genes followed a different pattern in peel and pulp tissues. After fruit detachment and incubation at 20 degrees C for up to 6 days, ACS1 mRNA slightly increased, ACO1 experienced a substantial increment and ACO2 declined. In the peel, these changes were advanced by exogenous ethylene and partially inhibited by 1-MCP. In the pulp, 1-MCP repressed most of the changes in the expression of biosynthetic genes, while ethylene had almost no effects. Expression of ethylene perception and signaling genes was barely affected by ethylene or 1-MCP. Collectively, a differential transcriptional regulation of ethylene biosynthetic genes operates in peel and pulp, and support the notion of non-climacteric ripening in loquat fruits. Ethylene action, however, appears to be required to sustain or maintain the expression of specific genes. (C) 2016 Published by Elsevier GmbH.Enriqueta Alos was recipient of a post-doctoral contract JAE-DocCSIC (Fondo Social Europeo). The financial support of the researchgrants FP7-PEOPLE-2011-CIG-2011-303652 (Marie Curie Actions, European Union), AGL-2009-11558 and AGL-2012-34573 (Ministerio Economia y Competitividad, Spain), GV/2012/036 (Generalitat Valenciana, Spain) and PROMETEOII 2014/27 (Generalitat Valenciana) is gratefully acknowledged.Alós, E.; Martinez Fuentes, A.; Reig Valor, C.; Mesejo Conejos, C.; Rodrigo, M.; Agustí Fonfría, M.; Zacarias, L. (2017). Ethylene biosynthesis and perception during ripening of loquat fruit (Eriobotrya japonica Lindl.). Journal of Plant Physiology. 210:64-71. https://doi.org/10.1016/j.jplph.2016.12.008S647121
Conocimiento y creación: Creatio in sapientia en Juan Escoto Eriúgena
Dentro de los estudios dedicados al pensamie nto medieva l la figura de Jua n Escoto Eriúgena aparece, sin lugar a dudas, particularmente rodeada de un halo de misterio, de fascinación, pero, sobre todo, de polémica. Este hecho ofrece la justificación de que el maestro carolingio haya sido objeto de una gran diversidad de interpretaciones a lo largo de la historia de la filosofía. En efecto, el irlandés ha sido calificado por igual como panteísta, monista, místico, racionalista, agnóstico, precursor de la filosofía moderna y del idealismo, y, a su vez, ha sido vinculado también a la mejor tradición patrística, que, a través de él, alcanzaría a la filosofía escolástica
Counterterms and dual holographic anomalies in CS gravity
The holographic Weyl anomaly associated to Chern-Simons gravity in 2n+1
dimensions is proportional to the Euler term in 2n dimensions, with no
contributions from the Weyl tensor. We compute the holographic energy-momentum
tensor associated to Chern-Simons gravity directly from the action, in an
arbitrary odd-dimensional spacetime. We show, in particular, that the
counterterms rendering the action finite contain only terms of the Lovelock
type.Comment: 10 pages, no figure
Monitoring new long-lasting intravitreal formulation for glaucoma with vitreous images using optical coherence tomography
Intravitreal injection is the gold standard therapeutic option for posterior segment patholo-gies, and long-lasting release is necessary to avoid reinjections. There is no effective intravitreal treatment for glaucoma or other optic neuropathies in daily practice, nor is there a non-invasive method to monitor drug levels in the vitreous. Here we show that a glaucoma treatment combining a hypotensive and neuroprotective intravitreal formulation (IF) of brimonidine–Laponite (BRI/LAP) can be monitored non-invasively using vitreoretinal interface imaging captured with optical coherence tomography (OCT) over 24 weeks of follow-up. Qualitative and quantitative characterisation was achieved by analysing the changes in vitreous (VIT) signal intensity, expressed as a ratio of retinal pigment epithelium (RPE) intensity. Vitreous hyperreflective aggregates mixed in the vitreous and tended to settle on the retinal surface. Relative intensity and aggregate size progressively decreased over 24 weeks in treated rat eyes as the BRI/LAP IF degraded. VIT/RPE relative intensity and total aggregate area correlated with brimonidine levels measured in the eye. The OCT-derived VIT/RPE relative intensity may be a useful and objective marker for non-invasive monitoring of BRI/LAP IF
Functional Evaluation of the Visual Pathway in Patients with Multiple Sclerosis Using a Multifunction Stimulator Monitor
Objectives. To assess the capability of the vision monitor unit Monpack One of detecting visual function alterations in patients with multiple sclerosis (MS) and to evaluate the correlation between structural retinal parameters and functional measurements obtained with this device. Methods. Forty-eight patients with MS and 46 healthy controls were included in a cross-sectional study. All participants underwent a complete functional evaluation of the visual pathway, which included low-contrast visual acuity (LCVA), contrast sensitivity vision (CSV), automated perimetry, multifocal visual evoked potentials (mfVEPs), and pattern electroretinogram (ERG). All tests were performed using the vision monitor unit Monpack One (Metrovision, France), a multifunction stimulator device. Retinal structural measurements were obtained in all subjects using Triton swept source optical coherence tomography (Topcon, Japan). Results. Patients with MS presented reduced low-contrast VA (p<0.001) and reduced CSV at medium (p=0.001, p=0.013) and low (p=0.001, p=0.002) spatial frequencies. All visual field parameters were found to be altered in MS patients compared with controls (<= 0.001). Patients with MS presented lower amplitude of the P100 waveform of the mfVEP in areas corresponding to central (p<0.001), inferonasal (p=0.001), and inferotemporal (p=0.003) retina. The pattern ERG did not show significant differences. Significant correlations were observed between structural retinal measurements and functional parameters, especially between the inner macular areas and measurements corresponding to contrast sensitivity and perimetry indexes. Conclusions. Patients with MS present visual dysfunction detectable with the vision monitor unit Monpack One. This device may be a fast and useful tool to provide a full evaluation of axonal damage in patients with multiple sclerosis
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