Synthesis of PDMS-metal oxide hybrid nanocomposites using an in situ sol-gel route

Organic-inorganic hybrid nanocomposites are widely studied and applied in broad areas because of their ability to combine the flexibility, low density of the organic materials with the hardness, strength, thermal stability, good optical and electronic properties of the inorganic materials. Polydimethylsiloxane (PDMS) due to its excellent elasticity, transparency, and biocompatibility has been extensively employed as the organic host matrix for nanocomposites. For the inorganic component, titanium dioxide and barium titanate are broadly explored as they possess outstanding physical, optical and electronic properties. In our experiment, PDMS-TiO2 and PDMS-BaTiO3 hybrid nanocomposites were fabricated based on in-situ sol-gel technique. By changing the amount of metal precursors, transparent and homogeneous PDMS-TiO2 and PDMS-BaTiO3 hybrid films with various compositions were obtained. Two structural models of these two types of hybrids were stated and verified by the results of characterization. The structures of the hybrid films were examined by a conjunction of FTIR and FTRaman. The morphologies of the cross-sectional areas of the films were characterized by FESEM. An Ellipsometer and an automatic capacitance meter were utilized to evaluate the refractive index and dielectric constant of these composites respectively. A simultaneous DSC/TGA instrument was applied to measure the thermal properties. For PDMS-TiO2 hybrids, the higher the ratio of titanium precursor added, the higher the refractive index and the dielectric constant of the composites are. The highest values achieved of refractive index and dielectric constant were 1.74 and 15.5 respectively for sample PDMS-TiO2 (1-6). However, when the ratio of titanium precursor to PDMS was as high as 20 to 1, phase separation occurred as evidenced by SEM images, refractive index and dielectric constant decreased. For PDMS-BaTiO3 hybrids, with the increase of barium and titanium precursors in the system, the refractive index and dielectric constant of the composites increased. The highest value was attained in sample PDMS-BaTiO3 (1-6) with a refractive index of 1.6 and a dielectric constant of 12.2. However, phase separation appeared in SEM images for sample PDMS-BaTiO3 (1-8), the refractive index and dielectric constant reduced to lower values. Different compositions of PDMS-TiO2 and PDMS-BaTiO3 hybrid films were annealed at 60 °C and 100 °C, the influences on the refractive index, dielectric constant, and thermal properties were investigated.

Development of Vapor Deposited Silica Sol-Gel Particles for a Bioactive Materials System to Direct Osteoblast Behavior

Tissue engineering and regenerative medicine have emerged in an effort to generate replacement tissues capable of restoring native tissue structure and function, but because of the complexity of biologic system, this has proven to be much harder than originally anticipated. Silica based bioactive glasses are popular as biomaterials because of their ability to enhance osteogenesis and angiogenesis. Sol-gel processing methods are popular in generating these materials because it offers: 1) mild processing conditions; 2) easily controlled structure and composition; 3) the ability to incorporate biological molecules; and 4) inherent biocompatibility. The goal of this work was to develop a bioactive vaporization system for the deposition of silica sol-gel particles as a means to modify the material properties of a substrate at the nano- and micro- level to better mimic the instructive conditions of native bone tissue, promoting appropriate osteoblast attachment, proliferation, and differentiation as a means for supporting bone tissue regeneration. The size distribution, morphology and degradation behavior of the vapor deposited sol-gel particles developed here were found to be dependent upon formulation (H2O:TMOS, pH, Ca/P incorporation) and manufacturing (substrate surface character, deposition time). Additionally, deposition of these particles onto substrates can be used to modify overall substrate properties including hydrophobicity, roughness, and topography. Deposition of Ca/P sol particles induced apatite-like mineral formation on both two- and three-dimensional materials when exposed to body fluids. Gene expression analysis suggests that Ca/P sol particles induce upregulation osteoblast gene expression (Runx2, OPN, OCN) in preosteoblasts during early culture time points. Upon further modification-specifically increasing particle stability-these Ca/P sol particles possess the potential to serve as a simple and unique means to modify biomaterial surface properties as a means to direct osteoblast differentiation.

Who gets the high quality jobs ten years after compulsory school?

Good work quality is crucial for employee well-being and health. Indicators of work quality are, among others, aspects of one’s work organization and learning opportunities. Based on the Job-Demands Control model we investigate if a) young employees are confronted with different combinations of job characteristics, b) cluster membership is predicted through socio-demographic and educational factors as well as positive self-evaluations and health, and c) cluster membership leads to different associations with job-related and general well-being. Based on TREE (Transition from Education to Employment) data we found three clusters of job characteristics, i.e. high resources – low demands, medium resources – medium demands, and low resources – high demands. Likelihood to be in a more favourable group was higher for females and young employees who reported more positive self-evaluations and higher learning efforts after compulsory school. Young employees in more favourable groups also reported higher levels of job-related and general well-being.

When the prey gets too big: an uncommon road accident involving a motorcyclist, a car and a bird

We present the postmortem findings of a fatal road accident involving a motorcyclist, a car, and a common buzzard. Both the motorcyclist and the bird died on the scene of the accident and were examined by postmortem full-body CT and autopsy. In addition, a facial injury of the motorcyclist was compared with the dimensions of the buzzard’s beak and claws by 3D scan technologies. Blood splatters collected on the bird’s beak, feet, and tail were examined by DNA analysis. The overall findings suggested a collision of a common buzzard with a motorcyclist in full speed, causing the motorcyclist to lose control of his vehicle and crash with an approaching car on the oncoming lane.

Etude des relations entre la pluie, le sol, le relief, la couverture végétale et l'érosion dans la région de Mandraka

Le relief accidenté, le climat agressif favorisé par l’Alizé, ainsi que l’étroite dépendance de la population de l’exploitation forestière et de l’exploitation agricole sans dispositifs de protection antiérosifs, sont les contextes qui permettent de dire que la région de Mandraka est sujette au problème d’érosion. L’étude a pour objectif de déterminer les relations entre les caractéristiques du sol, son mode d’occupation, les précipitations ainsi que l’érosion dans la région de Mandraka et ce en vue d’un aménagement rationnel. Des dispositifs pour la mesure de pertes en terre et de ruissellement ont été matérialisés sur des parcelles d’expérimentation. A cet effet, le choix de ces parcelles a porté sur le mode d’occupation du sol (sous terrains aménagés, sous « tavy », sous « savoka », et sous forêt naturelle), sur la similitude des pentes et sur leur localisation de manière à ce qu’elles soient situées sur les mi-versants. Les résultats ont montré que le sol dans cette région contient un taux de matière organique satisfaisant à élevé (2,41 à 3,74% de MO), lui permettant une bonne stabilité structurale (Is = 0,85 et K = 0,08). Les pertes en terre (0,13 à 20,93t/ha/an) et les ruissellements (0,3 à 5%) obtenus indiquent que l’érosion est faible à accélérée suivant le mode d’occupation du sol. En deux ans d’aménagement, les terrasses se sont stabilisées et les racines de Vetiveria zizanoides peuvent remplacer les fascines initialement installées pour tenir les talus. Toutefois, l’exposition du sol à la battance de la pluie et la mauvaise infiltration d’eau de ruissellement dans le sol accélèrent le phénomène d’érosion. Par ailleurs, il y a l’efficacité de la SCV sans brûlis bien qu’il s’agit de la première année d’expérience. Dans ces conditions, un plan d’aménagement simplifié a été proposé en vue (i) de protéger le sol contre la battance de la pluie, (ii) de réduire les transports solides par l’érosion et (iii) d’améliorer l’infiltration d’eau du sol.

Ein schön news Geystliches Lied : Ach Gott was sol ich singen, mein frewd die ist mir fern, [etc.]

In Fraktur

Sol Liptzin: Arthur Schnitzler [Rezension]

Paula Arnold

Ein schön new Lied, von nützbarlichen dingen : wie sich ein Christ trösten sol, in trübsal, angst un[d] not. Im thon, Hilff Got das mir gelinge

In Fraktur

Contradecir el sol: vida nocturna en Mendoza

Este video es parte de una serie de producciones realizadas por alumnos de la Carrera de Comunicación Social de la UNCuyo, como trabajo final de la Cátedra de Televisión y Medios Audiovisuales en el año 2006. Los mismos participaron de una muestra audiovisual en el Cine de la Universidad en agosto de 2007. Son trabajos periodísticos y documentales de alumnos avanzados de la carrera, en formato profesional, abordando temáticas sociales, políticas, culturales y de arte, haciendo visible realidades y personajes de la provincia. Según alumnos y docentes, estos vídeos “van al encuentro del público mendocino para que nos conozca, critique, reflexione, sonría y se emocione…" CONTRADECIR EL SOL es una investigación periodística sobre la vida nocturna mendocina en la voz de los que la trabajan, disfrutan y transitan.

Respuestas antiguas y contemporáneas ante el anuncio de catástrofes : Píndaro, el Peán 9 ante el eclipse de sol y los pronósticos del cambio climático

El presente artículo investiga algunas respuestas de la sociedad ante el pronóstico de calamidades comunitarias, estableciendo una comparación entre la respuesta de una comunidad antigua y algunas respuestas de la sociedad globalizada del siglo XXI ante los pronósticos científicos concernientes al cambio climático. En el campo disciplinar de la filología, se propone una lectura más compleja del Peán 9 de Píndaro (fr. 52k Maehler = A1 Rutherford), que busca dar cuenta del fenómeno del eclipse de sol, descrito por el poeta como un signo de catástrofes comunitarias, en el marco de los posibles conocimientos astronómicos de la época, y en la red de significados implícita en las formas de pensamiento simbólico propias de la Grecia arcaica. Tanto las actitudes antiguas como las actuales ante el anuncio de calamidades comunitarias se consideran desde una perspectiva antropológica apoyada en la investigación moderna sobre mitología.

Distantes espejos y reflejos de un mismo sol : el "sentimiento solar" de Julio Cortázar como culminación de su Antropología poética en poética histórica

La singular trayectoria de Julio Cortázar traza una parábola que parte de su inicial situación como escritor mentalmente colonizado (Jauretche) para arribar a una toma de conciencia político-histórica que lo impele a denunciar el genocidio cultural perpetrado por el imperialismo norteamericano y a defender las revoluciones socialistas de su tiempo. En este sentido, nuestro trabajo pretende indagar en la conversión de su antropología poética en poética histórica, entendiendo que los problemas metafísicos que plantea la primera desde una dimensión estrictamente literaria se abren al campo geopolítico a través de la confluencia entre política de la literatura y política del escritor (Rancière). Seleccionamos para ello un amplio corpus de textos y analizamos la evolución de la poética cortazariana en relación a la configuración de los sujetos populares. Observamos que éstos se muestran inicialmente como una alteridad radical (Baudrillard) respecto del yo enunciador, para constituir posteriormente la encarnación de un paradigma cultural que posibilita una existencia auténtica a través de la solidaridad y el encuentro con los otros (García Canclini). Finalmente, nos detendremos en el “sentimiento solar" y en los “hombres-puente" como símbolos de un Cortázar maduro y esperanzado que propone el equilibrio entre polaridades como condición necesaria para la verdadera revolución.