SANS study of hybrid silica aerogels under "in situ" uniaxial compression

We have modified the inorganic silica network of aerogels with polydimethylsiloxane (PDMS), a hydroxyl-terminated polymer, to obtain an organic modified silicate (ORMOSIL). Reactions were assisted by high-power ultrasounds. The resulting gels were dried under supercritical conditions of the solvent to obtain a monolithic sono-aerogel. The mechanical behaviour of these aerogels can be tuned from brittle to rubbery as a function of the organic polymer content. In order to determine the links between the mechanical behaviour and modifications made to the microstructure, SANS (small-angle neutron scattering) experiments were carried out. To measure the intensities under "in situ" uniaxial compression of the aerogel, a specific sample-holder was built. Under uniaxial compression the 2D-diagrams were significantly anisotropic (butterfly pattern), indicating the rearrangement of the polymer. The form factor of these aerogels is described well by two correlation lengths, small microporous silica clusters surrounded by entangled polymer chains of 6 nm average size (blobs), which form a larger secondary level of agglomerates governed by the "frozen-in" elastic constraints.Comisión Interministerial de Ciencia y Tecnología MAT2005-1583European Commission CT-2003-50592

Intrasession Repeatability of Biometric Measurements Obtained with a Low-Coherence Interferometry System in Pseudophakic Eyes

Purpose: To evaluate the intrasession repeatability of the biometric measurements obtained with a low-coherence reflectometry optical biometer in pseudophakic eyes implanted with two different types of intraocular lens (IOL). Methods: Prospective, single-center, comparative study including 69 eyes of 69 patients with ages ranging from 51 to 92 years. Previous uncomplicated cataract surgery had been performed in all patients 1 to 2 months before measurements, with implantation of the Acrysof SN60WF IOL in 35 eyes (35 patients, group 1) and the IOL Akreos MI60 in 34 eyes (34 patients, group 2). A complete postoperative ophthalmological examination was performed including three consecutive measurements with the “Aladdin” system from (Topcon, Japan). Intrasession repeatability of axial length (AXL), anterior chamber depth (ACD) and IOL thickness (IOLT) were assessed with the within-subject standard deviation (Sw), intraobserver precision (1.96 × Sw), coefficient of variation (CV) and intraclass correlation coefficient (ICC). Results: The Sw for AXL measurements was 0.03 and 0.05 mm in groups 1 and 2, respectively, with ICC of 1.000 and 0.999 (CV: 0.14% and 0.22%) (p ≤ 0.031). Concerning pseudophakic ACD, the Sw was 0.03 and 0.09 mm in groups 1 and 2, respectively, with ICC of 0.992 and 0.956 (CV: 0.55% and 1.75%) (p ≤ 0.021). The variability of IOLT measurements was high in both groups, with Sw of 0.12 and 0.29 mm for groups 1 and 2 (p = .008), respectively, and ICC of 0.065 and 0.770 (CV: 20.84% and 62.39%). Conclusions: The optical biometer “Aladdin” (Topcon, Japan) provides consistent measurements of AXL and ACD in pseudophakic eyes. However, there is a limitation in the consistency of IOLT measurements that should be investigated further.This work was supported by the Ministerio de Economía y Competitividad [Ramón y Cajal, RYC-2016-20471]

Decreased Perifoveal Sensitivity Detected by Microperimetry in Patients Using Hydroxychloroquine and without Visual Field and Fundoscopic Anomalies

Purpose. To evaluate the usefulness of microperimetry in the early detection of the ocular anomalies associated with the use of hydroxychloroquine. Methods. Prospective comparative case series study comprising 14 healthy eyes of 7 patients (group A) and 14 eyes of 7 patients under treatment with hydroxychloroquine for the treatment of rheumatologic diseases and without fundoscopic or perimetric anomalies (group B). A comprehensive ophthalmological examination including microperimetry (MP) and spectraldomain optical coherence tomography was performed in both groups. Results. No significant differences were found in mean MP foveal sensitivity between groups (P = 0.18). However, mean MP overall sensitivity was significantly higher in group A (29.05 ± 0.57 dB versus group B, 26.05 ± 2.75 dB; P < 0.001). Significantly higher sensitivity values were obtained in group A in comparison to group B for the three eccentric loci evaluated (P < 0.001). Conclusion. Microperimetry seems to be a useful tool for the early detection of retinal damage in patients treated with hydroxychloroquine

Lente de contacto híbrida de geometría inversa en córnea irregular con presencia de isla central tras cirugía LASIK

La lente híbrida de geometría inversa PS ofrece una mejoría de la calidad visual en pacientes con córneas irregulares tras cirugía refractiva miópica, mostrándose como una excelente opción en aquellos casos en que el insuficiente lecho corneal imposibilita retratamientos posteriores

Relationship between Medium-Term Changes in Intraocular Lens Position and Refraction after Cataract Surgery with Two Different Models of Monofocal Lenses

The aim of this prospective descriptive study was to characterize the variations of the clinical effective lens position (ELP) (considering paraxial optics and postoperative data) and the intraocular lens (IOL) position, using “eye” data gathered from a 6-month follow-up of patients who underwent uneventful cataract surgery. Patients were implanted with two different monofocal IOLs: AcrySof IQ SN60WF (Alcon) (Group 1, 247 eyes) and Akreos MI60L (Bausch & Lomb) (Group 2, 104 eyes). No significant differences were found between groups concerning spherical equivalent (SE), axial length, and clinical ELP changes, from 1 to 6 months after surgery (p ≥ 0.516). A more positive change in postoperative anterior chamber depth was found in Group 2, but the difference did not reach statistical significance (p = 0.065). No significant moderate to strong correlations were found between the changes in clinical ELP and preoperative data. The correlation between the changes in SE and clinical ELP over time was strong and statistically significant (groups 1 and 2: r = 0.957 and r = 0.993, p < 0.001). In conclusion, changes in refraction from 1 to 6 months after cataract surgery, with single-piece monofocal IOLs, are not clinically relevant, which correlates with the presence of good positional stability. These changes cannot be predicted preoperatively and considered in IOL power calculations.D.P.P. was supported by the Ministry of Economy, Industry, and Competitiveness of Spain, within the program Ramón y Cajal, RYC-2016-20471

Bioactivity of wollastonite/aerogels composites obtained from a TEOS-MTES matrix

Organic-inorganic hybrid materials were synthesized by controlled hydrolysis of tetraethoxysilane (TEOS), methyltrimethoxysilane (MTES), synthetic wollastonite powders and polydimethylsiloxane (PDMS) in an ethanol solution. Aerogels were prepared from acid hydrolysis of TEOS and MTES with different volume ratio in ethanol, followed by addition of wollastonite powder and PDMS in order to obtain aerogels with 20 wt% of PDMS and 5 wt% of CaO of the total silica. Finally, when the wet gels were obtained, they were supercritically dried at 260°C and 90 bar, in ethanol. In order to obtain its bioactivity, one method for surface activation is based on a wet chemical alkaline treatment. The particular interest of this study is that we introduce hybrid aerogels, in a 1 M solution of NaOH, for 30 s at room temperature. We evaluate the bioactivity of TEOS-MTES aerogel when immersed in a static volume of simulated body fluid (SBF). An apatite layer of spherical-shaped particles of uniform size smaller than 5 microns is observed to form on the surface of the aerogels after 25 days soaking in SBF.Ministerio de Ciencia e Innovación MAT2005-01583Junta de Andalucía TEP 79

Argumentación y metáfora en el discurso político en torno a la inmigración

The conceptual metaphor, developed within the framework of cognitive linguistics, constitutes a tool for both supporting and refuting trains of argument; it therefore enables a collection of polyphonic voices to be identified, reflecting opposing ideologies and representing their particular vision of the events under debate. From a corpus of texts belonging to the “hypergenre” of the social debate concerning immigration, we analyse the conceptual and linguistic metaphors that categorize the host country and the image of immigrants. Through a study of this imagery, we demonstrate that the choice of source domains and of conceptual structures generates a virtual dialogue between opposing ideologies—supporters and detractors of the phenomenon of immigration— and show that, in effect, metaphor plays an important role in the process of argument.La metáfora conceptual, desarrollada en el marco de la lingu..stica cognitiva, constituye una herramienta más al servicio de las operaciones de apoyo y refutación propias de la secuencia argumentativa y, por ello, permite reconocer un juego de voces polifónicas a través del cual se reflejan ideologías opuestas que representan su particular visión sobre los acontecimientos debatidos. A partir de un corpus de textos pertenecientes al hipergénero del debate social en torno a la inmigración, se analizan las metáforas conceptuales y lingüisticas que categorizan el país receptor de inmigrantes y la imagen que de estos se tiene. Mediante el estudio de esta imaginería se comprueba cómo la selección de los dominios fuente y de las estructuras conceptuales que generan propician el diálogo virtual entre ideologías opuestas, defensora y detractora del fenómeno de la inmigración, y se pone de manifiesto que, efectivamente, la metáfora desempeña una función relevante en la argumentació

Multichannel perimetric alterations in systemic lupus erythematosus treated with hydroxychloroquine

AbstractSystemic lupus erythematosus (SLE) is a multiorgan autoimmune disease of unknown etiology with many clinical manifestations.We report the first case of SLE in which visual alterations were evaluated with multichannel perimetry.Some achromatic and color vision alterations may be present in SLE, especially when treated with hydroxychloroquine. The sensitivity losses detected in the chromatic channels in the central zone of the visual field were consistent with the results of the FM 100 Hue color test. Likewise, the multichannel perimetry detected sensitivity losses in the parafoveal area for both chromatic channels, especially for the blue-yellow

El viraje educativo, de la presencialidad a la Educación a Distancia en tiempos de pandemia (COVID-19)

Las Tecnologías de Información y Comunicación (TIC) son recursos de apoyo para el docente, quien a través de una planificación estratégica puede promover el aprendizaje colaborativo de los estudiantes, más aún frente a la necesidad de participar en la Educación a Distancia. En consecuencia, este artículo muestra la experiencia generada, a partir de las vivencias de los participantes (docentes) en el proceso de cambio de la modalidad educativa impartida, en las instituciones educativas seleccionadas durante la cuarentena social, producto de la pandemia originada por el COVID-19. Metodológicamente consistió en una Investigación cualitativa (enfoque etnográfico/Narrativo) bajo el paradigma interpretativo. Se utilizaron las técnicas de observación participante y entrevista a profundidad. En cuanto a los hallazgos, se observó un amplio grado de disposición por parte de los profesionales, quienes consideran que el proceso de formación puede ser mucho más favorecedor, haciendo uso de las TIC

The open veins of Latin America: Long-term physical trade flows (1900-2016)

Latin America has long played a key role in the global provision of natural resources. Most of the continent's economies are net exporters of low-value, primary products and importers of manufactured goods at a high price. This pattern of specialised trade has highly negative consequences for economic development, the environment, and the local population's wellbeing. Yet to date, little empirical evidence has been collected on Latin America's total contribution to the rest of the world's regions in historical perspective. Applying the Material Flow Accounting methodology, this paper estimates the physical and monetary trade of 16 Latin American economies between 1900 and 2016. Our results show that: (i) yearly net exports of materials went from 4 Mt to 610 Mt between 1900 and 2016, and greatly accelerated since the World War II. (ii) Latin America is a net exporter of most types of materials (fossil fuels, non-energy minerals and biomass), so it harbours socio-environmental problems associated with different types of extractivism. (iii) Different regional export patterns exist: Andeans export subsoil (mining and energy carriers) while the rest export soil (land-based products). The countries with the lowest net exports are the smallest in size and with the highest population density. (iv) Europe and the USA have historically received most of the imports, but since the end of the twentieth century, the Southeast Asia region is the biggest importer of materials from Latin America. (v) The price received for exported material is much lower than the price paid for imported material; and (vi) various historical periods can be differentiated regarding the relationship between economic growth and physical trade balance